&EFA
            United States
            Environmental Protection
            Agency
            Municipal Environmental Research
            Laboratory
            Cincinnati OH 45268
EPA-600/9-84-021
September 1984
            Research and Development
                                      ^>^
Proceedings
8th
United States/Japan
Conference on
Sewage Treatment
Technology
1981
       October 12-13
       Cincinnati, Ohio
                October 19-20
                Washington, D.C.

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                                                                  EPA-600/9-84-021
                                              PROCEEDINGS
                                EIGHTH UNITED STATES/JAPAN CONFERENCE ON
                                       SEWAGE TREATMENT TECHNOLOGY
                                  CINCINNATI, OHIO: OCTOBER 12-13, 1981
                                  WASHINGTON, D.C.: OCTOBER 19-20, 1981

•~j
vi
O
                                    OFFICE OF INTERNATIONAL ACTIVITIES
                                             OFFICE OF WATER
                                          WASHINGTON, D.C. 20460

                                    OFFICE OF RESEARCH AND DEVELOPMENT
                                          WASHINGTON, D.C. 20460
                                          CINCINNATI, OHIO 45268
                                     U.S. Environmental Protection Agency
                                     Region 5, Library (PL-12J)
                                     77 West Jackson Boulevacd, 12th Floor
                                     Chicago, IL  60604-3590
                                  U.S.  ENVIRONMENTAL PROTECTION AGENCY
                                   OFFICE  OF RESEARCH AND DEVELOPMENT
                                         CINCINNATI, OHIO 45268

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                          FOREWORD


      The maintenance of clean water supplies and the
management of municipal and industrial wastes are vital
elements in the protection of the environment.

      The participants  in  the  United States-Japan cooperative
 project on sewage  treatment  technology  have  completed their
 eighth  conference.   These conferences,  held  at  18-month
 intervals,  give  the  scientists  and  engineers of the  cooper-
 ating agencies an  opportunity to study  and compare the
 latest  practices and developments in the  United States and
 Japan.   These Proceedings of  the Eighth Conference comprise
 a  useful body of knowledge on sewage treatment, which will
 be available not only  to  Japan  and  the  United States but
 also  to all nations  of the world who desire  it.
                        Anne  M.  Gorsuch
                         Administrator
 Washington,  D.C.
                             iii

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                  CONTENTS









FOREWORD	  ill






JAPANESE DELEGATION	:	   vi






U.S.-CINCINNATI DELEGATION	vil






U.S.-WASHINGTON, D.C	viii






JOI^T COMMUNIQUE	    l






JAPANESE PAPERS	    3






UNITED STATES PAPERS	627

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            JAPANESE DELEGATION

DR. TAKESHI KUBO
   Co-Chairman of Conference and Head of Delegation
   President,
   Japan Sewage Works Agency
   No. 18 Mori Building
   2-3-13 Toranomon
   Minato-Ku, Tokyo, Japan

TOKUJI ANNAKA
   Assistant Head, Regional Sewerage Works Division
   Department of Sewerage and Sewage Purification
   Ministry of Construction
   2-1-3 Kasumigaseki
   Chiyoda-Ku, Tokyo 100, Japan

SHIGEKI MIYAKOSHI
   Senior Technical Advisor,
   Sewage Works Bureau
   City of Yokohama
   1-1 Minato-machi, Naka-Ku,
   Yokohama, Kanagawa 231, Japan

DR. KEN MURAKAMI
   Chief, Water Quality Section
   Public Works Research Institute
   Ministry of Construction
   Tsukub?- Science City
   Ibaraki-Pref., 305 Japan

TETSUICHI NONAKA
   Senior Technical Advisor,
   Sewage Works Bureau
   Tokyo Metropolitan Government
   2-6-2 Otemachi
   Chiyoda-Ku, Tokyo 100, Japan

KAZUHIRO TANAKA
   Researcher,
   Research and Technology Development Division
   Japan Sewage Works Agency
   No. 5141 Nishihara Shimosasame
   Toda City, Saitma Pref., Japan

TAKASHI YONEDA
   Director, Sewage Works Bureau
   City of Kyoto
   Teranachi, Oikenoboru
   Nakagyo-Ku, Kyoto 604, Japan

                     VI

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                     UNITED STATES/CINCINNATI DELEGATION

JOHN J. CONVERY                        DR. ATAL E. ERALP
  General Chairman of Conference and     Environmental Engineer,
  Head of Cincinnati U.S. Delegation     Ultimate Disposal Section
  Director, Wastewater Research Div      Treatment Process Development Branch
  Municipal Environmental Research Lab   Wastewater Research Division
  U.S. Environmental Protection Agency   Municipal Environmental Research Lab
  Cincinnati, Ohio 45268                 U.S. Environmental Protection Agency
FRANCIS T. MAYO                          Cincinnati, Ohio 45268
  Director, Municipal Environmental    DR. JOSEPH B. FARRELL
  Research Laboratory                    Chief, Ultimate Disposal Section
  U.S. Environmental Protection Agency   Treatment Process Development Branch
  Cincinnati, Ohio 45268                 Wastewater Research Division
         T T?T?iri7                           Municipal Environmental Research Lab
LOUib w. LbrKh                                    .                  .
  Deputy Director, Municipal Environ-    U'.S- Environmental Protection Agency
  mental Research Laboratory             Cincinnati, Ohio 45268
  U.S. Environmental Protection Agency DR. IRWIN J. KUGELMAN
  Cincinnati, Ohio 45268                 Chief, Pilot & Field Evaluation Sec
EDWIN F  BARTH                           Technology Development Support Branch
  Chief! Biological Treatment Section    Wastewater Research Division
  m   ^   ^. -n       TAI     i. T,    i.   Municipal Environmental Research Lab
  Treatment Process Development Branch     „      .
  Wastewater Research Division           V'S-.Environmental Protection Agency
  ,,..,_.      ^ i r,      t-ri.   Cincinnati, Ohio 45268
  Municipal Environmental Research Lab
  U.S. Environmental Protection Agency GERALD N. MCDERMOTT
  Cincinnati, Ohio 45268                 Senior Engineer,
DOLLOFF F. BISHOP                        Environmental Control
  Chief, Technology Development Support  The Procter & Gamble Company
  Branch, Wastewater Research Division   Hillcrest Tower, Room 3-E-29
  ,...,„.      _ , _      I_TI_   7162 Reading Road
  Municipal Environmental Research Lab     .   .    .   ,  .  ,,-„„„
  U.S. Environmental Protection Agency   Cincinnati, Ohio 45222
  Cincinnati, Ohio 45268               JOHN M. SMITH
DR. CARL A. BRUNNER                      Chief> Urban systems Management Sec
  Chief, Systems & Engineering Evalu-    Systems & Engineering Evaluation Br
  ation Branch, Wastewater Research Div  Wastewater Research Division
  Municipal Environmental Research Lab   MunlclPal Environmental Research Lab
  U.S. Environmental Protection Agency   U'S'.Environmental Protection Agency
  Cincinnati, Ohio 45268                 Cincinnati, Ohio 45268

DR. SIDNEY A. HANNAH                   ™S B' WELLS
  Research Chemist,                      Manager,
  Physical-Chemical Treatment Section    Control Systems
  Wastewater Research Division           S^n"1116^ of1Publxc Works
  Municipal Environmental Research Lab   27°° South Belmont Avenue
  U.S. Environmental Protection Agency   Indianapolis, Indiana 46221
  Cincinnati, Ohio 45268

                                     vii

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                 UNITED STATES/WASHINGTON, B.C. DELEGATION
JOHN J. CONVERY
 General Chairman of the Conference
 Director, Wastewater Research Div
 Municipal Environmental Research Lab
 U.S. Environmental Protection Agency
 Cincinnati, Ohio 45268

WILLIAM J. LACY
 Washington Chairman of Conference
 Director, Water & Waste Management
 Monitoring Research Division   RD-680
 Office of Monitoring & Quality
 Assurance
 U.S. Environmental Protection Agency
 Washington, D.C. 20460

DR. JOHN W. HERNANDEZ
 Deputy Administrator   A-101
 U.S. Environmental Protection Agency
 Washington, D.C. 20460
                                       ROBERT J.  FOXEN
                                        Chief, Engineering & Economic Sec
                                        Facility Requirements Division
                                        Office of Water
                                        U.S.  Environmental Protection Agency
                                        Washington,  D.C.  20460

                                       DR.  SAMBHUNATH GHOSH
                                        Manager,  Bioengineering Research
                                        Institute of Gas Technology
                                        3424  South State Street
                                        Chicago,  Illinoia 60616

                                       ALAN B. HATS
                                        Chief, Policy & Guindance Branch
                                        Facility Requirements Division
                                        Office of Water
                                        U.S.  Environmental Protection Agency
                                        Washington,  D.C.  20460
DR. JOHN F. ANDREWS
 Department of Civil Engineering
 University of Houston
 Houston, Texas 77004
                                       DAVID W. HILL
                                        Chief, Ambient Monitoring Section
                                        Surveillance & Analysis Division
                                        U.S. Enviromental Protection Agency
                                        College Station Road

JAMES V. BASILICO                       AthetlS> ^^ 3°6°2
 Deputy Director, Waste Management Div DR> ANDREW p> JOVANOVICH
 Environmental Engineering & Technology Assistant Adminlstrator   ^.572
 Office of Research & Technology RD-681  ,...    ,.        ,    _,   .
                  , „          .        Office of Research & Development
 U.S. Environmental Protection Agency   u>g> Environmental Protection Agency
 Washington, D.C. 20460                 Washington, D.C. 20460
DR. EDWARD H. BRYAN
 Program Director,
 Water Resources & Environmental
 Engineering
 National Science Foundation
 Washington, D.C. 20037

ROBERT A. CANHAM
 Executive Director,
 Water Pollution Control Federation
 2626 Pennsylvania Avenue
 Washington, D.C. 20037
                                       HENRY L. LONGEST, II
                                        Director, Water Program Operations
                                        Office of Water
                                        U.S. Environmental Protection Agency
                                        Washington, D.C. 20460

                                       WILLIAM A. ROSENKRANZ
                                        Director, Waste Management Division
                                        Environmental Engineering &   RD-681
                                        Technology
                                        Office of Research & Development
                                        U.S. Environmental Protection Agency
                                        Washington, D.C. 20460
                                     vm

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UNITED STATES AND JAPAN DELEGATES TO THE EIGHTH CONFERENCE,
   ANDREW W. BREIDENBACH ENVIRONMENTAL RESEARCH CENTER,
                     CINCINNATI, OHIO

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MR. FRANCIS T.  MAYO,  DIRECTOR,  MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY AND MR.
JOHN J. CONVERY,  GENERAL CHAIRMAN OF THE EIGHTH CONFERENCE AT A WORKING SESSION,
                                 CINCINNATI,  OHIO

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MRS. ANNE M. GORSUCH, ADMINISTRATOR,  USEPA GREETS DR. TAKESHI KUBO, JAPANESE TEAM
LEADER AND JAPANESE DELEGATES TO TH^1  EIGHTH CONFERENCE IN WASHINGTON, D.C.

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roi      W> HERNANDEZ> JR" DEPOTY ADMINISTRATOR, IISEPA AND DR. TAKESHI KIIBO   JAPANESE
TEAM LEADER EXCHANGE GREETINGS AT THE WASHINGTON, D.C. SEMINAR 0- THE EIGH™'CONFERENCE

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JAPANESE AND U.S.  DELEGATES  ON  A  FIELD VISIT  IN  THE WASHINGTON,  D.C.  AREA

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                     JOINT  COMMUNIQUE


             EIGHTH UNITED STATES/JAPAN CONFERENCE
                 ON SEWAGE TREATMENT TECHNOLOGY

             CINCINNATI,  OHIO  OCTOBER 12-14,  1981
             WASHINGTON,  D.C.  OCTOBER 19-20,  1981
1.   The Eighth United States/Japan Conference on Sewage Treat-
     ment Technology was held in Cincinnati,  Ohio from October
     12-14, 1981 and in Washington, D.C.  from October 19-20,  1981.

2.   The Japanese Delegation headed by Dr.  Takeshi Kubo, Pres-
     ident of the Japan Sewage Works Agency was composed of two
     representatives from the Ministry of Construction, two
     representatives of the Japan Sewage  Works Agency and one
     each from the Cities of Tokyo, Kyoto and Yokohama.

3.   The United States Delegation in Cincinnati consisted of
     Mr. John J. Convery, Director, Wastewater Research Division,
     Municipal Environmental Research Laboratory, U.S. Environ-
     mental Protection Agency as General  Conference Chairman,
     eleven federal government representatives, one representa-
     tive from industry and one representative from local gov-
     ernment (Indianapolis).  The Washington, D.C. Delegation
     consisted of Mr. William J. Lacy, Director,  Water and Waste
     Management, Monitoring and Research  Division, Office of
     Monitoring and Quality Assurance, U.S. Environmental Pro-
     tection Agency as Washington Conference Chairman as well as
     eleven federal government representatives, one representative
     of the Water Pollution Control Federation, one representative
     from industry and one representative from academia.

4.   The Chairmanship of the Conference was shared by Dr. Takeshi
     Kubo and Mr. John J. Convery in Cincinnati and Dr. Takashi
     Kubo and Mr. William J. Lacy in Washington,  D.C.

5.   During the Conference, papers relating to joint research
     projects on sludge treatment/disposal including utilization
     of sludge as a resource, coincineration of refuse and sludge,
     and composting were presented by both sides.  Data and find-
     ings on the joint research projects  were useful to the develop-

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     ment of improved control technology practices  for
     each country.   A decision was made to expand the
     scope of the joint research projects conducted by
     the two countries to include wastewater reuse.

6.   Principal topics of the Conference were innovations
     in wastewater treatment as well as sludge management
     disposal and toxics removal, pretreatment, combined
     industrial-municipal treatment and nutrient control.
     The discussions which followed the presentations were
     also useful to both countries.

7.   Field visits in Cincinnati, Ohio;  Tampa,  Florida;
     Washington, D.C.; Denver, Colorado and Los Angeles,
     California are planned to inspect  wastewater treat-
     ment facilities in these areas.

8.   Recent engineers exchanges between the two countries
     included a three-week visit in 1981 to Japan by Dr.
     .Irwin J. Kugelman of the Wastewater Research Division,
     Municipal Environmental Research Laboratory, U.S. Environ-
     mental Protection Agency.  Mr. M.  Hirabayashi of the  Japan
     Sewage Works Agency is now studying at the County Sanitation
     Districts of Los Angeles County.  Both parties agreed to
     continue the engineers exchange program.

9.   Dr. Taskeshi Kubo announced that after ten years he would
     transfer the future responsibilities of Japanese Chairman
     of the Project Agreement to Mr. T. Tamaki, Director,  Depart-
     ment of Sewerage and Sewage Purification, Ministry of Construc-
     tion.  Dr. Kubo's leadership and significant contributions
     to the cooperative agreement was acknowledged in the  form
     of an EPA commemorative plaque presented by the EPA Deputy
     Administration, Dr. John W. Hernandez, Jr.

10.  Both sides agreed that the time interval between conferences
     should be extended from once every eighteen months to once
     every two years.

11.  It was proposed by the Japanese side that the Ninth  Confer-
     ence shall be held in Tokyo, Japan about October 1983.

12.  A Proceedings of the Conference will be printed in English
     and in Japanese.

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                           JAPANESE PAPERS
PERFORMANCE OF SEWAGE SLUDGE DEWATERING BY SCREW PRESS	    5
   Kazuhiro Tanaka, Section Chief, Research and Technology
   Division, Japan Sewage Works Agency

UTILIZATION OF SEWAGE SLUDGE AS RESOURCES	  41
   Tetsuichi Nonaka, Senior Technical Advisor,
   Sewage Works Bureau, Tokyo Metropolitan Government

EXPERIMENT ON INCINERATION OF MUNICIPAL REFUSE AND SEWAGE
SLUDGE IN KYOTO CITY	  67
   Takashi Yoneda, Director, Sewage Works Bureau,
   City of Kyoto

NEW ASPECTS OF SLUDGE INCINERATION IN YOKOHAMA	  89
   Shigeki Miyakoshi, Senior Technical Advisor,
   Sewage Works Bureau, City of Yokohama

CURRENT STATUS OF AUTOMATIC MONITORING OF WATER QUALITY
IN SEWAGE TREATMENT	143
   Ken Murakami, Water Quality Section, Water Quality
   Control Division, Public Works Research Institute,
   Ministry of Construction

PILOT PLANT STUDY FOR TREATMENT OF COMBINED FISH-PROCESSING
AND DOMESTIC WASTE IN MAKURAZAKI CITY	163
   Kazuhiro Tanaka, Section Chief, Research and Technology
   Development Division, Japan Sewage Works Agency

TECHNICAL EVALUATION OF DEEP WELL BIOLOGICAL PROCESS	199
   M. Kuribayashi and K. Murakami, Water Quality
   Control Division, Public Works Research Institute,
   Ministry of Construction

DEPHOSPHORIZATION OF SEWAGE BY CONTACT CRYSTALIZATION
OF CALCIUM APATITE	283
   Tetsuichi Nonaka, Senior Technical Advisor,
   Sewage Works Bureau, Tokyo Metropolitan Government

ADVANCED TREATMENT PROJECT FOR EUTROPHICATION CONTROL
IN LAKE BIWA	313
   Kazuhiro Tanaka, Section Chief, Research and Technology
   Development Division, Japan Sewage Works Agency

                                                       (continued)

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                          JAPANESE  PAPERS  (continued)
EFFECT OF DETERGENTS AND SOAP ON MUNICIPAL WASTEWATER TREATMENT... 385
   K. Kobori,  H.  Watanabe and K.  Murakami, Water Quality
   Control Division, Public Works Research Institute,
   Ministry of Construction


FIFTH FIVE-YEAR SEWERAGE SYSTEM DEVELOPMENT PROGRAM AND LONG-
RANGE PROSPECTS FOR DEVELOPMENT OF SEWERAGE SYSTEMS	  441
    Tsutomu Tamaki, Director, Department of Sewerage
    and Sewage Purification, Ministry of Construction


CURRENT ISSUES IN WATER POLLUTION CONTROL ADMINISTRATION
IN JAPAN	  477
    Toshiki Oshio, Councilor for Engineering Affairs,
    Environment Agency, Government of Japan

REGIONAL SLUDGE MANAGEMENT PROGRAM IN THE TOKYO BAY BASIN	  489
    Dr. Takeshi Kubo, President,
    Japan Sewage Works Agency

STATUS AND OUTLOOK OF SLUDGE TREATMENT AND DISPOSAL IN
KYOTO CITY	  531
    Takashi Yoneda, Director, Sewage Works Bureau,
    City of Kyoto


COLLECTIVE PRETREATMENT OF INDUSTRIAL WASTEWATER FROM
MINOR ENTERPRISES IN YOKOHAMA	  549
    Shigeki Miyakoshi, Senior Technical Advisor,
    Sewage Works Bureau, City of Yokohama

AGRICULTURAL USE OF SEWAGE SLUDGE	  585
    Kazuhiro Tanaka, Section Chief, Research and Technology
    Division,  Japan Sewage Works Agency

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                                Eighth US/JAPAN Conference
                                        on
                                Sewage Treatment Technology
           PERFORMANCE
                   OF
SEWAGE SLUDGE DEWATERING
         BY SCREW PRESS
               October 13-14, 1981

               Cincinnati, Ohio USA
 The work described in this paper was not funded by the
 U.S. Environmental Protection Agency.  The contents do
 not necessarily reflect the views of the Agency and no
 official endorsement should be inferred.
       Kazuhiro Tanaka

       Section Chief,

       Research and Technology Development Division,

       Japan Sewage Works Agency

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1.    INTRODUCTION

          Dewatering devices  used in sewage  treatment  plants  in Japan  have
     largely depended on vacuum filters  or filter  presses  using slaked lime
     and ferric chloride.
          It has been found on the application  of  these dewatering devices
     that the dewatered cake  dosed of large  amounts  of slaked lime produces
     hexavalent chromium when incinerated in a  furnace, and is too bulky
     to handle.
          In recent years,  the use of polymers  (cationic and  anionic
     polyelectrolytes)  as dewatering coagulants has  solved these problems.
          In order to dewater polymer-coagulated sludges,  centrifuges
     were put to practical  use,  but were found  defective in that moisture
     content of the cake remains 80% or  more.
          Very recently, belt filter presses have  come into use as they
     save electrical energy,  and reduce  the  moisture content  of the cake,
     more than do centrifuges.
          In many sewage treatment plants belt  filter  presses are con-
     sidered for a new or additional installation  of dewatering devices
     because of their excellent  performance.
          In addition to belt presses, screw presses discussed here are
     another alternatives for sewage treatment  plants  since they are claimed
     to be able to reduce the cake moisture  content  to 60% or lower.
          The screw press uses polymers  as dewatering coagulants as does
     the belt filter press, and also employs steam heating in compression
     processes.
          Originally, the screw press was developed  for dewatering  sludge
     generated from wastewater treatment facilities  of fish meal processing.
     Its modification for application to dewatering  sewage sludge has  been
     studied for years.
          The screw press as  a dewatering device is  a  tapered Archimedes'
     screw consisting of a  screw shaft and a perforated metal cylinder
     (cylindrical screen).  The space between the  screw shaft and the
     perforated metal cylinder is made smaller  the nearer it  goes toward
     the outlet.
          As the screw blades turn, the  sludge  moves toward the outlet
     while being compressed gradually for filtration and dewatering.

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2.
As a result, the dewatering efficiency increases with the progress
of the sludge along the screw press dewatering device.
     The screw press has been claimed to achieve very low moisture
content of sludge cake, to run without noise and vibration in
operation, to be easy to maintain, and to further improve the
dewatering efficiency by making use of steam.
     A total of six screw presses has now been operated at three
sewage treatment plants in Japan.
     The results of a survey on the dewatering performance of the
screw presses at these three sewage treatment plants are reported
here.

DESCRIPTION OF SCREW PRESS
     A cross section of the screw press is shown in Fig. 1.
     A detailed view of the screen is shown  in Fig. 2.
                                                 Sludge
       Steam
       drain
                                                        Steam
                  Cake
                       Filtrate
       (l) Hopper    (g) Screen     (5) Screw shaft     (4) Screw blade
       Q>) Outlet squeezing ring    (§) Cake outlet     (?) Filtrate outlet
       Fig. 1  Cross-  sectional view of  screw press dewatering device
                        Reinforced rib
                Cylindrical screen
              Punching plate
                    Fig. 2  Detailed view of the screen

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     Polymer-conditioned sludge is charged into the hopper of the
 screw press.  Free porewater contained in the sludge floe is
 gravitationally discharged from the coarse-mesh punching plate set
 near the hopper.  This zone including a coarse-mesh punching plate
 is called the draining zone.
 The polymer-conditioned sludge is then gradually transfered by re-
 volving screw-blades.  As the space between the cylindrical punch-
 ing plate and the main body of the screw gets smaller the farther
 it goes away from the inlet, the remaining porewater and adhering
 water contained in the sludge are gradually removed.  This zone is
 called the pressing zone.  Finally, the sludge is compressed at
 high pressure by a tapered cone.  Namely, the sludge is worked under
 a shearing force for further compression and filtration.  This zone
 is called the squeezing zone.
     In a screw press dewatering device, the draining, pressing and
 squeezing processes are integrated for continuous production of
 dewatered cake.
     The cylindrical screen is an assembly of stainless steel
punching plates having a number of small holes (2 to 3 mm 0).
The filtrate is discharged from these small holes.  The sludge
 floes form bridges at the inside of small holes of the punching
plates, and function to trap sludge floes smaller than the punch-
 ing plate holes.  The filtrate which includes much suspended solids
 is guided into a solid-liquid separation tank where suspended
solids are settled for separation from liquid.  The supernatant of
the solid-liquid separation tank is then returned to the wastewater
treatment system, while the settled suspended solids are returned
to the sludge storage tank where they are mixed with thickened
sludge and charged again into the hopper of the screw press.
     The screw press is equipped with a hollow screw shaft into
which steam (1 kg/cm2-G)  is fed for heating of sludge through
thermal conduction.
     The dewatering efficiency can be increased by steam heating.
It is inferred that the steam heating will reduce the viscosity of
the sludge and hence reduce the drag resistance to increase the
dewatering efficiency.

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     The cylindrical screen is covered with a shell to prevent foul
odors generated from the heated sludge and also to stop the filtrate
from spattering
     The specifications of the screw presses surveyed are listed
in Table 1.
           Table 1  Specifications of screw presses
^"""""^-^^^ Model
Item ^ — ^_^
Diameter of
cylindrical screen
D (mm)
Screen length,
L (mm)
Screw pitch,
P (mm)
Overall length
(mm)
Width
(mm)
Overall height
(mm)
Weight
(ton)
Power requirement
(kW)
Revolution speed
(rpm)
Steam supply rate
(kg/hr)
Surveyed model at
tlishinomiya
Surveyed Model at
Kurume
Surveyed Model at
Sakai
0100
100
1000
100
1800
900
1100
0.7
0.4
o.rv
0.53
20
0


0200
200
2000
200
3000
1000
1200
1
1.5
0.08^
1.28
30
O

0
0500
500
6000
450
7500
1400
1700
5
2.2
0.08^
0.32
90
0


0800
800
8000
700
10200
2300
2000
16
5.5
0.026^
0.316
-


O
0900
900
8000
800
10200
2500
2200
20
5.5
0.02^
0.24
200
0


01000
1000
10000
800
12500
2700
2300
23
5.5
0.046^
0.18
200

O

Remarks









lkg/cm2




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     The models of the screw presses are expressed in terms of diameter
     of cylindrical screen (mm).   Namely, the cylindrical screen diameter
     of the 900 model is 900 mm.

3.    SLUDGE CHARACTERISTICS AND SELECTION OF COAGULANTS

 3.1  Sludge Characteristics

           Of the sludge treatment facilities of the three sewage treat-
      ment plants surveyed, two adopt anaerobic digestion and mechanical
      dewatering, and the other dewaters raw mixed sludge mechanically.
      The sewage treatment plants are outlined in Table 2.
      The characteristics of the  sludge to be dewatered at each treat-
      ment plant are shown in Table 3.
           In the sludge characteristics analyzed, the ignition loss of
      coarse suspended solids is  measured as follows.

      Ignition loss of coarse suspended solids

           Take a 100 ml sample of sludge,  pour it over a 100-mesh sieve,
      and wash with tap water.
      Heat the residue at 105°C,  and weigh the evaporation residue.
      Then,  heat the evaporation  residue at 600°C, and weigh the
      ignition residue.
      Calculate the ignition loss of coarse suspended solids according
      to the following formula.

           Ignition loss of coarse suspended solids (%)
           = [100-mesh evaporation residue (g/1)  - 100-mesh ignition
             residue (g/1)] / [SS of sludge sample (g/1)] x 100
                                10

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Table 2  Outline of surveyed sewage treatment plants
Name of
municipality
Nishinomiya
Kurume
Sakai
Sewer system
Combined
system
Separate
system
Separate
system
Maximum daily sewage
flow (m3/day)
126,000
21,300
3,500
Sewage treatment system
Conventional activated sludge
process
Conventional activated sludge
process
High rate trickling filter
and conventional activated
sludge process
Sludge treatment system
Gravitational thicknening -
Anaerobic digestion - Elutria-
tion - Mechanical dewatering -
Incineration (by multiple
hearth furnace)
Gravitational thicknening -
Anaerobic digestion - Elutria-
tion - Mechanical dewatering
Mechanical dewatering

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                                     Table 3  Characteristics of tested sludges
Name of
municipality

Nishinomiya



Kurume




Sakai


Type of sludge


Anaerobically
digested and
elutriated
sludge

Anaerobically
digested and
elutriated
sludge

Raw mixed
sludge

Season


Summer


Winter

Summer


Winter
Summer

Winter
TS (%)


3,92


3.36

2.02


2.26
1.78

1.14
SS (%)


3.54


3.00

1.96


2.17
1.68

0.91
DS (%)


0.38


0.37

0.06


0.09
0.10

0.23
VTS/TS
(%)

54.3


53.9

65.2


66.1
58.4

72.0
PH (-)


7.6


7.6

2.0


7.6
6.9

6.8
M-alkalinity
(mg/1)

3,150


2,890

1,110


2,310
1,210

815
Ignition loss of
coarse suspended
solids (%)
4.1


4.8

5.2


6.1
8.2

21.7
ro

-------
 3.2  SELECTION OF COAGULANTS

           It was found that the use of cationic polyelectrolyte in com-
      bination with anionic polyelectrolyte is very effective for sludge
      dewatering.
           It was also found that the strength of floe coagulated by the
      polyelectrolytes alone is weak, and therefore, that the use of
      quick lime or slaked lime as a coagulation aid improves this
      strength.
           Tests were conducted at the sewage treatment plants to select
      the appropriate coagulants.  The selected polymers and coagulation
      aids are as shown in Table 4.

4.   DEWATERING PERFORMANCE

 4.1  Test Results

           The factors affecting dewatering performance of the screw
      press are sludge characteristics, chemical dosing conditions
      (particularly lime dosing), steam supply rate, screw shaft re-
      volution speed, and blade height at the cake outlet, punching
      plate hole size, steam pressure and temperature, etc.  The
      dewatering tests were conducted with the screw shaft revolution
      speed, slaked lime dosing rate, and steam supply rate as
      operational parameters.  The results summarized in Figs. 3 through
      5 are discussed below.
                                   13

-------
Table 4  Kinds of coagulants and aids,  and their dosing rates
Name of
municipality
Nishinomiya
Kurume
Sakai
Type of sludge
Anaeroblcally
digested
sludge
Anaerobically
digested
sludge
Raw mixed
sludge
Season
—
—
Summer
Winter
Chemicals
Anionic polymer
Brand
Diaf loc
AP-520
Kurif loc
PA-331
Kurif loc
PA-331
Dosing rate
(%/DS)
0.3
0.4
0.2
Cationic polymer
Brand
Diaf loc
KP-201G
Kurifix
CP-604
Kurifix
CP-634
Dosing rate
(%/DS)
0.2
0.8
0.6
0.8
Inorganic aids
Aids
Slaked
lime
Quick
lime
Slaked
lime
Dosing rate
(%/DS)
10
30
20
30

-------
                                              Cake moisture  content  (%)
O O  t» 50
g O  O ID
£• 3  H- M
j" Qi  H- »
jj H-  O. rt
*~8£

~^Str
     H- ID
     3 rt
     lQ C

     M ID
     pi 3
     rt
     ID O
      < M
      W rt
      H C
      H' H
      0 ID
      C

      01 8
      0 3
     •O rt
      ID ID
      K 3
      Pi rt
      rt
      p. pi
      O 3

-------
                  Model & 100
                                                            Model 0  1000
   80 -
   75 .
   70 •
65
-P
tt)
-P
C
o
0  60
0)
+J
Ul
•H
0)
,x
<0
u
   55 -
   50 -
                           Model s6 100;
                           lime 0%;
                           not heated
                                                    Model s& 1000;
                                                    lime 30%;
                                                    not heated
                                                              ^_     / Model 0  1000;
                                                                       lime 20%;
                                                                     D Cheated
                                                                       Model 0 1000;
                                                                       lime 30%;
                                                                       heated
                                                                  Model  0  1000;
                                                                  lime 40%;
                                                                  heated
   45
   40 '
                    /  A /
                 Model 0 100;
                 lime 30%;
                 heated
                  0.5    1                 ' 10                  100
                              Solids  processing rate (kg-DS/hr)
                                                                   200 300
              Fig. 4  Relationship between cake* moisture  content and solids
                      processing rate under various operational conditions (2)
                      (Kurume)
                                          16

-------
                                   Model i 200
                                                                Model 0 800
  801
   75-
   70-,
I  651
5  60-
0)
8
   50.
                             200;
    Model 0
    not heated
    lime 10
Model 0 200;
not heated
lime 20%
               Model i 200
               not heated
               lime 30%
                             Model 0 800;'not heated;
                             lime 0%
                     Model «J 200;
                     not heated;
                          0%

                        Model 0 800;
                        not heated;
                        lime 10%
                                           ' Model    800;
                                            not  heated;
                                            lime 20%
                                                          Model 0 800;
                                                          not heated;
                                                          lime 30%
                                Model «i 200;
                                heated;
                                lime 20%
                                      Model <6  200; heated;  lime 30%
          0.2
 0.5
                                             i
                                            10
        5     10            50     100

Solids processing rate  (kg-DS/h)
                                                            500
                   Fig. 5  Relationship between  cake moisture content and
                           solids processing rate under  various operational (3)
                            (Sakai)
                                           17

-------
4.2  Effect of Screw Shaft Revolution Speed

          In a Sewage Treatment  Plant at Kurume  City,  tests  were  conducted
     on a Model 01000 type screw press to determine the dewatering per-
     formance with the revolution speeds of 0.046,  0.069,  0.092 and 0.123
     rpm.
     The dewatering performance  is shown in Fig. 6
     With increase in the revolution speed, the  solids processing rate
     was increased, but the moisture content in  the cake also increased.
     With increase in the speed  of the dewatering device,  the screw feed
     rate increases, increasing  the solids processing rate.
     Therefore, the compressing  and dewatering time in the dewatering
     device becomes shorter, which increases the moisture content in the
     sludge cake.
     In the other two sewage treatment plants, in Nishinomiya and Sakai,
     the same tendency as in Kurume was noticed.

4.3  Effect of Lime Dosing Rate

          In a Sewage Treatment Plant, in Nishinomiya, Hyogo,
     anaerobically digested and  elutriated sludge was tested with the
     lime dosing rate changed to 5%, 10%, and 20%.
     In this test, the cake moisture content changed as shown in  Fig. 7.
     It was found that lime dosing is highly effective in reducing the
     moisture content in the cake.  In Kurume, the same survey was
     conducted, changing the lime dosing rate to 20%, 30% and 40%.  Up to
     30% dosing of lime, the same tendency as in Nishinomiya was  noticed.
     However, more than 40% dosing of lime, the moisture content  in the
     cake was not significantly improved.
                                 18

-------
   80
~  75 ~
•P
0)
-P

o
o
(1)
M
P
•P
U)
•H
0)
   70 ~
   65 ~
   60  -
       T
                               Model      :  jrflOOO
                               Steam      :  300 kg/hr
                               Quick lime:  30%/DS
                                                         -400
                                                         -200
                                                         rioo
              0.046
                         0.069
0.092
0.123
                                                               CO
                                                               D
                                                        -300   g1

                                                               •H
                                                               10
                                                               10
                                                               0)
                                                               O
                                                               0.

                                                               in
                                                               •a
                                                               •H
                                                               H
                                                               O
                                                               CO
               Screw shaft revolution speed
         Fig. 6  Relationship between cake moisture content, solids
                 processing rate  and screw shaft revolution speed
                 (Kurume)
                                    19

-------
    80 _
    75-
4J
C
o
o
p
4J
CO
    70-
    65-
                                                 Kurume, Model 01000, heated
          Nishinomiya, Model 0900, heated
    60-
                     10
—r—
 40
                                                                         H
                  20            30


            Slaked lime dosing rate (%/DS)


Fiq. 7  Slaked lime dosing rate vs. cake moisture content
                                    20

-------
4.4  Effect of Steam Supply

          In Nishinomiya,  anaerobically digested and elutriated sludge
     was tested with the steam supply rate changed by using the model
     #900 screw press.   The steam supply rate vs.  cake moisture content
     relationship is shown in Fig.  8.  It can be seen from Fig. 8 that
     the steam supply contributes toward improving the cake moisture
     content.
          The temperature  distribution within the  steam-heated screw
     press is shown in  Fig. 9.
          To asses the  effect of  steam heating on  viscosity and filtration
     rate of sludge,  laboratory experiments were conducted using Nishinomiya
     sludge.   The results  are shown in Fig. 10 and Fig.  11.
     It is found that the  viscosity of polymer-coagulated sludge decreases
     with increase in the  steam supply rate;  the viscosity is  minimized at
     a sludge temperature  of 80°C to 90°C,  and the filtration  time of
     sludge is minimized at a temperature of  about 60°C.   The  reduction
     in the liquid-phase drag resistance due  to change in the  liquid-
     phase viscosity of polymer-coagulated sludge  is considered beneficial
     to the improvement of the sludge dewatering efficiency.
          The characteristics of  the filtrate and  its supernatant obtained
     in Nishinomiya are as shown  in Table 5.
          According to  Table 5, COD,,  and BODC of  the filtrate and its
                                   Mn        ->
     supernatant are higher when  heated with  steam than when not supplied
     with steam.   Whether  this phenomenon is  ascribable to temperature
     rise due to steam  supply or  other factors is  as yet  unknown.   Anyway,
     the increase in the organic  loadings to  be sent back to the waste-
     water treatment system is negligibly small.
                                    21

-------
    80 T
£   75

4J

0)
3
+J
U)
Winter
    70 -
                      Svonmer
m
o
   65 -
                                              Nishinomiya
                                                Model jz!900
   60 -
                                   100            200


                       Steam supply rate  (kg/hr)
             Fig.  8  Cake moisture content vs.  steam supply rate
                                 22

-------
 100-

  90-

  80-

J 70 .

*60 J
0)
M
3
I
  50 -

  40 .

  30 -

  20 -

  10 -
                                                                            ul.  14
                                                                           Jul.  6
                                                                    Jul. 3
                                               *   I I  Range of observed
                                               ••• [  temperatures
                               —l	1	1	1	1       I	1	
                                No.3   No.4   No.5   No.6   No.7   Cake  Filtrate
          —i	1        i
           Raw    No.l   No.2
           sludge
            Sludge
            charge
                                   Screw Press ^900



























I





Jo 1











]





*fo 2

1















No. 3














*


No. 4











1





to. 5

















No. 6







_^-



No. 7

^ 	 '
                                                                          Cake
                                                                          discharge
                          Filtrate
          Fig. 9   Temperature distribution in Screw Press Model 0900
                                        23

-------
                110(0)
  100-
cu

o
w
o
u
in
0)
cn
T!
a
    90-
    80-
    70-
    60-
                           Figures indicate  viscosity (c.p.)


                           Figures in parentheses  indicate heating

                           time  (roin.)
20   30   40   50  60    70   80   90

          Temperature of sludge  (,°C)
                                                 100
           Fig. 10 Temperature  vs.  viscosity
                                      24

-------
u

0)

CO
a
o
2
•P
   400-
   300-
   200-
   100-
Sample:  25 ml of coagulated sludge


         (Nishinomiya).





     Filtrate:   20 ml
                                              Filtrate:   15  ml
                                              Filtrate:   10  ml
                                              Filtrate:   5  ml
               25           60      80     100




                       Temperature of sludge  C°C)









            Fig.  11  Effect of steam supply on filtration time
                                    25

-------
               Table 5  Characteristics of filtrate and  its  supernatant  obtained by sedimentation tank

                        (Screw press Model 0900, Nishinomiya)

Filtrate
Supernatant
obtained by
sedimentat-
ion tank
Steam
Supplied at
a rate of
200 kg/hr
Not
supplied
Supplied at
a rate of
200 kg/hr
Not
supplied
TS
(mg/i)
5,400
(6^40^4,410)
5,570
(7,970^4,250)
4,030
(4^360^3,770)
4,010
(4,340^3,750)
SS
(mg/i)
1,740
(3,370^660)
1,785
(4^30^540)
370
(890^156)
220
(514V39)
DS
(mg/JO
3,660
(3,850^3,470)
3,790
(4,190^3,450)
3,660
(3,850^3470)
3,790
(4,190^3,450)
PH
-
12.0
(12.1VL1.9)
12.4
(12.5^12.2)
11.8
(11.9^11.6)
12.3
(12.5^12.2)
D-COD
(mg/£)
174
(195VL46)
147
(173^134)
213
(237^190)
158
(195^106)
D-BOD
(mg/£)
273
(444VL72)
173
(371^80)
299
(428VL85)
180
(304^64)
Remarks
Steam
1 kg/cm2 G

Steam
1 kg/cm2G

PO
cr>

-------
4.r>  Effect of Diameter of Cylindrical Screen

          In Nishinomiya comparisions of the dewatering efficiencies
     and scale effects were studied using models 0100,  0200, 0500, and
     0900 type screw presses.
          The solids processing rate increased with increase in screw
     shaft revolution speed and also with increase in diameter of the
     cylindrical screen (Fig. 3 and Fig. 6).
     The solids processing rate was 0.3 to 2.5 kg-DS/hr. for the Model
     0100, 3 to 15 kg-DS/hr. for the Model 0200, 30 to 80 kg-DS/hr. for
     the Model 0500 and 170 to 370 kg-DS/hr. for the Model 0900.
          Generally, the solids processing rate of the screw press is
     given by the following formula.

          Q = (V4)  x (Di2 - Da2)  x P x R x (1 - M/100) x 60 x r x n . . . (1)

          Where, Q  :  Solids processing rate (kg-DS/hr.)
                 D]  :  Diameter of cylindrical screen  (m)
                 Da :  Final outside diameter of screen shaft (m)
                 P  :  Screw pitch (m)
                 R  :  Screw shaft revolution speed  (rpm)
                 M  :  Cake moisture content (%)
                 r  :  Cake density (kg/m3)
                 r|  :  Cake transfer efficiency (-)

          The final outside diameter of screw shaft  (D2) of the test
     screw presses is portional to the diameter of cylindrical screen
     (Di), and the screw pitch (p) is also nearly proportional to the
     same.  If the cake transfer efficiency and cake density are constant,
     and the variations in cake moisture content are neglected, Eq.  (1)
     can be rewritten as follows.

          Q « D 3-R   	  (2)
                                      27

-------
The theoretical sludge retention time in the screw press is given by
the formula below.

     T = L/S = L/(P X R)  ..................................  (3)

     Where, T :  Theoretical sludge retention time in device  (min)
            L :  Length of cylindrical screen (m)
            S :  Cake transfer rate (m/min.)
            P :  Screw pitch  (m)
            R :  Screw revolution speed  (rpm)

     The sludge dewatering time can be considered to be nearly
equal to the theoretical retention time.
     As explained in the foregoing, the surveyed screw presses
have screw pitches (p) nearly proportional to the diameter of
cylindrical screen (Di ) .  The length of cylindrical screen  (L)  is
also designed to be nearly proportional to DI .
Thus, Eq.  (3) is rewritten as follows.
By combining Eqs.  (2) and  (4), the following formula is obtained.
         Di3/T
     Of the test data obtained in Nishinomiya, those obtained  for
a case where slaked lime was dosed  10%-, anionic polymer 0.3% and
cationic polymer 0.2% with steam supplied to the screw press were
selected to determine an empirical  formula  for the  solids processing
rate as follows.
                                  28

-------
     log Q = 2.9 log DI - 0.72 log T - 4.7  	  (6)

     Where, Q  :  Solids processing rate  (kg-DS/hr.)
            DI:  Diameter of cylindrical screen  (mm)
            T  :  Theoretical retention time (min.)

Eq.  (6) is graphically represented in Fig. 12.
This difference between Eq.  (5) and Eq.  (6) is probably due to the
assumption of a fixed cake moisture content in Eq.  (5).
     An empirical formula of cake moisture content was also derived
by using the same test data as follows.

     log M = 0.15 log DI - 0.10 log T + 1.61  	  (7)

     Where, M  :  Cake moisture content (%)
            T  :  Theoretical retention time (min.)

            DI:  Diameter of cylindrical screen  (mm)

Eq.  (7) is graphically represented in Fig. 13, in which the data
obtained in Sakai and Kurume are also plotted.
When the sewage sludge was dewatered by the screw press with slaked
lime dosing rate of 10% and steam supply, the cake moisture content
varied depending upon DI as follows.
     o Model 0100:  53 to 58%
     o Model 0200:  55 to 68%
     o Model 0500:  57 to 70%
     o Model 0900:  65 to 75%
                                 29

-------


T=50 min.
// T=67 min.


//. T=100 min.



100.
£
cn
o
i
*
(D
4J
R>
Ol
•-H
tn
0) ,
proce
Solids
1-

0.5-








T=25 min

A / .
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iff
It
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ill log Q - 2.9
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Legend
Retention Time
200 min.
150 min.
100 min.
67 min.
50 min.
37 min.
25 min.
13 min.
I U 1 Operational conditions
II 1 — 	
II J Tested
'I'
1 Slaked
/ •
An ion ic
Steam:
sludge: Anaerobically
digested and
elutriated sludge (SS, 3.5%)
lime : 10%/DS

polymer/cationic polymer: 0. 3%DS/0. 2%DS
Supplied

                100     200       500     900
             Diameter of cylindrical screen, DI (mm)

Fig. 12  Relationship  between  solids  processing rate and  diameter of
         cylindrical screen
                               30

-------
                               Cake moisture content  (%)
H-
13
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-------
When steam was not supplied to the screw press,  the cake water
content of the same sludge was as follows.
     o Model 0100:  75 to 77%
     o Model 0200:  72 to 76%
     o Model 0500:  67 to 70%
     o Model 0900:  71 to 76%

As demonstrated above, in case of steam supply dewatering the c.ake
moisture content increased with increase in the diameter of cylindrical
screen.   On the other hand, when steam was not supplied, the effect
of the diameter on the cake moisture content was not observed.  As
compared with the case without steam supply, the steam supply improved
the cake moisture content by about 20% for Model 0100, about 15% for
Model 0200, about 10% for Model 0500, and about 5% for Model 0900.
It is therefore deduced that under the constant steam pressure,
the effect of steam supply on the dewatering efficiency becomes
greater the smaller the diameter of cylindrical screen.  This is
probably due to the fact that the steam supply per unit weight of
solids increases with decrease in the diameter of cylindrical screen.
     Fig. 14 shows the relationship between the diameter of the
cylindrical screen and the steam supply rate per unit weight of
solids based upon the data in Nishinomiya.  From Fig. 14, the
following can be deduced.

 (1)  The steam supply rate is proportional to the diameter of the
     cylindrical screen  (Di).

 (2)  The solids processing rate is proportional to DI to the power
     of 2.3 to 2.9.
                                  32

-------
             1.9
                                                   •  Solids processing rate

                                                  •	..(kg/DS-hr)
      Steam supply rate

      per kg of solids

      (steam-kg/ DS-kg)
     I
1,000

QJ
4J


£
 I
 en


 
-------
 (3)  Namely, the steam supply rate per unit weight of solids is in
     inverse proportion to Dj to the power of 1.3 to 1.9.

     Accordingly, when steam is supplied, the cake moisture content
rises with increase in the diameter of the cylindrical screen.
On the other hand, in case of no steam supply, the cake moisture
content is unrelated to the diameter of the cylindrical screen.
     The steam supply rate is limited by the steam heat to be
transferred to sludge.  The currently available screw presses are
designed to transfer steam heat to the sludge through their screw
shafts.
The surface area of the screw shaft is proportional to the square
of the diameter of the cylindrical screen.
When the steam temperature is increased by increasing the  steam
pressure, sludge sticks on the heating surface of the screw shaft,
degrading the heating efficiency.  Therefore there is a upper limit
to which the steam pressure can be increased.  The theoretical steam
supply rate at the optimum steam pressure is governed by the square
of the diameter of the cylindrical screen.
     In the actual screw press, however, filling up efficiency of
the sludge is reduced with increase in the diameter of the cylindrical
screen, and the ratio of the heating surface available to  the total
screw shaft surface area is accordingly reduced.  For this reason,
the actual steam supply rate is proportional to the diameter of the
cylindrical screen (Di)  as shown in Fig. 14.
     Thus, for large diameters of cylindrical screen, the  following
measures will be necessary:

(1)  The screw shaft should be designed so that steam can  be supplied
     not only to the shaft, but also to the screw blade, in order to
     increase the heat transfer area.

(2)  The sludge should be filled up well in.

-------
     (3)   Solids processing rate should be limited to meet the steam
          supply rate.

5.    ECONOMICS OF SCREW PRESS AS COMPARED WITH OTHER DEWATERING DEVICES

          The Edagawa Sewage Treatment Plant,  in Nishinomiya,  has,  in
     addition to screw presses,  three belt type rotary vacuum  filters
     and  three stand type filter presses to dewater anaerobically digested
     and  elutriated sewage sludge.
          Accordingly,  data regarding the operation of these three  types
     of dewatering devices on the same sludge  was collected in Table 6.
     Based on this data,  an economic evaluation of the three types  of
     dewatering devices was made.  The dewatered sludge cake is incinerated
     in multiple hearth furnaces, and ash is disposed of for landfill
     outside the plant.
          The utility costs of 15.8 tons-DS/day dewatering and incineration
     facilities were estimated.   The transportation costs required  for ash
     disposal were also considered.
          The results of cost estimation are given in Table 7.
                                   35

-------
Table 6  Operational  conditions of dewatering devices
"^5^^^ Type of
^X^~--~^^ dewatering
^^v^^^'-^^devi ce
Item ^X^"^\_
Raw sludge con-
centration (SS)
Sludge process-
ing rate
Ferric chloride
dosing rate
Slaked lime dos-
ing rate
Anionic polymer
dosing rate
Cat ionic polymer
dosing rate
Steam supply
rate
Cake moisture
content
Solids process
ing rate
Solid removal
rate (SS)
Running time
%
m /hr/unit
%/DS
%/DS
%/DS
%/DS
kg/hr
%
Kg/m2/hr
%

Screw press
Anaerobically
digested and
elutriated
sludge, 3.5
7.5
—
10
0.3
0.2
200
70
*8.4
73
6 hrs . /day
(300 days/yr.)
Vacuum filter
Anaerobically
digested and
elutriated,
sludge, 3.5
7.0
3
25
-
-
-
79
11
95
6 hrs. /day
(300 days/yr.)
Filter press
Anaerobically
digested and
elutriated
sludge , 3.5
5.5
15
35
-
-
-
58
3.9
98
6 hrs . /day
(300 days/yr. }
* Per unit screen area
                        36

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                Table 7  Comparison of utility cost for dewatering and incineration
                                                                                        (based on 1979 price)

Utility cost
Ash
Dewatering cost



Slaked lime
Anionic polymer
Cationic polymer
Ferric chloride
Total of chemicals
Water
Electricity
Steam
Sub-total
Incineration cost
Sub-total
disposal cost
Grand Total
Screw press
Specific unit
137 kg/t-DS
4.11 kg/t-DS .
2.74 kg/t-DS
-

12 m3A-DS
80 KWH/t-DS
1050 kg/t-DS





Cost
(.¥/t-DS)
2,700
4,100
4,100
-
10,900
400
1,500
5,300
18,100
21,000
39,100
3,200
42,300
Vacuum filter
Specific unit
263 kg/t-DS
-
-
83.7 kg/t-DS

28 m3A-DS
145 KWH/t-DS
-





Cost
(¥/t-DS)
5,300
-
-
2,100
7,400
800
2,600
-
10,800
37,900
48,700
4,300
53,000
Filter press
Specific unit
357 kg/t-DS
-
-
403 kg/t-DS

6 m3/t-DS
140 KWH/t-DS
-





Cost
(¥/t-DS)
7,100
-
-
10,000
17,100
200
2,500
-
19,800
19,000
38,800
5,500
44,300
CA>

-------
In terms of the total amount of costs for utilities and ash disposal,
the screw press system costs about 5% less than the filter press
system and about 25% less than the vacuum filter system.
     In terms of utility costs of dewatering, the screw press system
costs about 60% more than the vacuum filter system, but about 5% less
than the filter press system.  The reason why the vacuum filter system
is most inexpensive is that its chemical consumption is the lowest.
The utility costs for the filter press system are high because it
uses large amounts of chemicals and electricity.
In the screw press system, the utility costs are not so low because
steam generation is costly though little electric power is consumed.
     In terms of the total amount of utility costs including
incineration costs, the screw press system is almost the same as
the filter press system, and costs about 25% less than the vacuum
filter system.
The difference in utility costs between the vacuum filter system
and the screw press system is due mainly to the incineration costs;
the sludge cake from the vacuum filter system contains much moisture
and requires much auxiliary fuel, while the sludge cake from the
screw press system can burn itself with little auxiliary fuel.
The filter press system and screw press system are nearly on a par
with each other in terms of both total utility cost and incineration
cost.
                              38

-------
6.    SUMMARY
          The performance of the screw press was  investigated  using
     anaerobically digested and elutriated sludge*  and  raw mixed  sludge
     obtained from the three sewage treatment  plants.   The results  are
     summarized below.

     (1)   The factors affecting the dewatering performance of  the
          screw press include sludge characteristics, chemical dosing
          conditions (particularly  slaked  lime dosing rate), steam
          supply rate,  screw shaft  revolution  speed, height of screw
          blade at the cake outlet,  and punching  metal  pore diameter.
          Of these factors,  the screw shaft revolution  speed,  slaked
          lime dosing rate,  and steam supply rate were  variated to
          investigate the dewatering performance.

     (2)   It was found  that  increase in the slaked  lime dosing rate
          leads to reduction of cake moisture  content,  that increase
          in the screw  shaft revolution speed  increases the cake
          moisture content and solids processing  rate,  and that in-
          crease in the steam supply rate,  reduces the cake moisture
          content.

     (3)   The theoretical solid processing rate is  proportional to  the
          cube of the diameter of the cylindrical screen, and  in  inverse
          proportion to the  sludge retention time.

     (4)   The moisture  content in cake increases  with increase in the
          diameter of the cylindrical screen when the sludge is steam-
          heated,  but remains almost unchanged if steam is not supplied.
          The steam supply rate is proportional to  the  diameter of  the
          cylindrical screen.   On the other hand, the solids processing
          rate proportional  to the cube of the diameter of the cylindrical
          screen.   Accordingly,  the  steam  supply  rate per unit weight of
          solids  is in  inverse proportion  to the  square of the diameter of
          the cylindrical screen.
                                  39

-------
     Accordingly,  the moisture  content  in  the  cake increases  with
     increase in the diameter of  the  cylindrical  screen.

(5)   From the test data available in  Nishinomiya,  empirical formulas
     for solids  processing rate and cake moisture  content were
     obtained for  screw press with steam supply and 10% dosing  of
     slaked lime.

          log Q  =  2.9 log Di -  0.72 log T  -  4.7
          log M  =  0.15 log Dj - 0.10  log T + 1.61

          Where, Q :   Solids processing rate (kg-DS/hr.)
                M :   Moisture  content  in  cake (%)
                DI:   Diameter  of cylindrical  screen (mm)
                T :   Theoretical retention  time  (min.)

(6)   Operational costs were compared  for the screw press, vacuum
     filter,  and filter press.
     In  terms of total utility  costs  including incineration and
     ash disposal  cost, the screw press system costs about 5% less
     than the filter press system, and  about 25%  less than the
     vacuum filter system.
     In  terms of the total utility costs inclusive of incineration
     costs,  the  screw press system is nearly on a  par with the
     filter  press  system,  and costs about  25%  less than the vacuum
     filter  system.
     In  terms of utility costs  for dewa>.ering  alone, the screw  press
     costs about 60% more  than  the vacuum  filter,  but about 5%  less
     than the filter press.
                                 40

-------
                                       Eighth US/Japan Conference

                                                on
                                       Sewage Treatment Technology
                UTILIZATION

                        OF

  SEWAGE  SLUDGE  AS RESOURCES
                  October 1981

               Cincinnati, U. S. A.
   The work described in this paper was not funded by the
   U.S. Environmental Protection Agency. The contents do
   not necessarily reflect the views of the Agency and no
   official endorsement should be inferred.
Tetsuichi Nonaka

Senior Technical Advisor,

Sewage Works Bureau

Tokyo Metropolitan Government
                           41

-------
1.  INTRODUCTION
        Recently,  turning  sewage  sludge  into  fuel or other  useful  resources
   has  been  seriously  talked  about.
        In the  past, however,  sewage  sludge was  dumped  as it was regarded
   as useless.
        Historically speaking,  there  was once a  time when sewage sludge was
   used as fertilizer  to a very limited  extent.  Until  recently, most  sewage
   sludge has been disposed of  chiefly in the form of landfill.
        Although landfill  is  productive  in the sense that it fills hollows,
   lowlands  and shores, etc.  to turn  them into useful lands, the sewage
   sludge, which is not a  good  filling material, has so far been disposed
   of as useless rather than  as useful.
        If we continue to  dispose of  sewage sludge as useless,  the dump
   sites, that  is, the landfill sites, will soon be filled  up.
   It is therefore mandatory  to establish some improved form of disposal
   by recycling sludge into marketable products.
        If the  sewage  sludge  produced in a city  is harnessed for urban
   development, it will go a  long way toward  improving  the  distribution
   economy as there will be no  need  to haul wastes out  of the  city and at
   the  same  time bring superfluous materials  into the city.
        In order to establish an  improved form of sludge disposal, it  will
   be necessary to promote research- and  development for sludge recycling
   technology,  application technology and distribution  system  for  recovered
   products.
        The  feasibility of sewage sludge harnessing is  dependent on the
   wise use  of  organic substances and trace  inorganic salts in the sludge.
   The  requirements for harnessing the sludge may be summarized as follows.
  1) Agricultural use
    a.  To be effective as  fertilizer or  for  soil conditioning.
    b.  Not to contaminate  the surface and ground waters through accumula-
       tion,  leaching, and inflitration  of pollutants.
    c.  Not to be detrimental  to plants.
    d.  Not to communicate  contaminants through the  food chain.
  2)  Use for grassy land
    Almost  the same  as agricultural use.
                                  42

-------
  3) Civil engineering use
    a. To meet engineering requirements such as strength.
    b. Not to leach out contaminants.
        Namely, the ideas of harnessing sewage sludge must be implemented
   while fulfilling these requirements.  For example, when It is planned
   to make products out of sludge cake or its ashes,  it is necessary to
   carefully study the sludge as a material physically and chemically,
   particularly from the viewpoint of  safety relating to the heavy metals
   contained, how to use and apply the products,  and  bow to make the pro-
   ducts on an industrial scale for the purpose of establishing a stabilized
   sludge recycling system.
2.  DEVELOPING COMPOST FROM SEWAGE SLUDGE
        Since 1976, the Tokyo Metropolitan Government has  promoted experiments
   on composing of sewage sludge, along with tests on the  agricultural
   use of compost, phytotoxicity surveys, and marketing system, etc.
        According to the interim results of these surveys, the Tokyo
                                           3
   Metropolitan Government installed a 10 ra /day composting plant  at the
   Minami-Tama Wastewater Treatment Plant in March 1980.  At present, this
   composting plant is performing well, producing 2 to 3 tons of compost
   a day.
        This paper deals with the harnessing of sewage sludge with emphasis
   on the Minami-Taraa composting plant and the results of  tests on the
   agricultural use of sludge compost.
 2.1 COMPOSTING PLANT OUTLINE
   2.1.1 Minami-Taraa Wastewater Treatment Plant
              The Minami-Tama Wastewater Treatment Plant is a separate
         sewer type plant treating the domestic wastewater of Tama New
         Town, and is located in the west of Tokyo.
              The sludge produced there contains low  concentrations of
         heavy metals,  and is suitable for agricultural use.  At the Minami-
         Tama Wastewater Treatment Plant, raw sludge  is added with slaked
         lime and ferric chloride and  then is dewatered through a filter
         press.
              The following are the 1980 daily average statistics recorded
         b.y the Minami-Tama Wastewater Treatment Plant.
                                      43

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                                                3
      .  Domestic wastewater treated  :   17,970 m
                                                3
      .  Sludge produced              :      209 m
      .  Sludge cake produced         :       15 tons
      .  Sludge cake incinerated      :       12 tons
2.1.2 Composting Plant
     a.  Principal features of the plant
        .  Area of premises
        .  Building floor space
          - Plant
          - Warehouse
        .  Processing capacity
:   3,164.9
   1,243.8 m'
     360.0 m'
       3,
   10 m /day (approx.  7 tons/day)
   in terms of sludge cake
   2 to 3 tons/day
   ¥400,000,000
        .  Output
        .  Construction cost
     b.  Flow sheet and operating method
             Figure 1 shows a flow sheet of the plant. (Refer to Fig. 1)

                                                   Exhaust Gas
                                                  Dram  Wash Water
                                                          (Filtrate Second Effluent)
                                 a^L-D®.—Ji
                                                 Composted Products
                             Hauling Compost
                    Fig. 1  Flow diagram of full-scale composting plant
                                44

-------
                           Fig. 1 (continued)
1 No          Description
„  .).       	  -
  '  Dewatered sludge hopper
  2  8elt.scale of sludge cake
  3  Jroshmq, mixing, granulating unit
  4  Composting tank
                              1 No of |
          Particulars
Capacity  . 10m3
Load cell, 2 Tons/H 0.75 kW
3.8 Tons/H, 30 kW
Capacity   52.5m'
                    ._  _  J
f,
6
7
8
9
'0
11
'?
13
14
15
16
'7

18
19
20
21

Transfer) Mechanical turner 1
Hauling hopper 1
Damper 1
Vibrating screen 1
Belt scale of products 1
Products' hopper '
Measuring hopper I
Bagging machine 1
Return compost hopper 1
Belt-scale of return compost ' 1
Composted products
Forklift 1
Truck for hauling

Blower for composting tank , 3
Exhaust gas fan 1
Scrubber ! 1
Circulation pump 2
I
Self-travel bucket, 45 m3 /H
Capacity : 10m3

Circular vibrating screen. 0.4 kW
Load eel I : 1.5 tons/H 0.75 kW
Capacity : 21 m3
Capacity : 0.5 m3
Belt conveyor type. 2 Tons/H
Capacity : 28 m3
Load cell, 3 tons/H. 0 75 kW

1Ton


Turbofan, 35 m'/min. 7.5 kW
Turbofan, 250 m'/min. 15 kW
Vertical 2-stage wash, 250 m3 /min.
Centrifugal pump, 0.5 m3 /min, 5.5 kW

Then- are  four compositing  tanks,  each measuring  18.8 m in length,
?. 1 m in width and 2.8 m  in depth.   A single mechanical turner
is installed to handle these four  tanks.
     The plant is fully automated,  and is operated as follows.
     Sludge  cake with a moisture content of about 70% is mixed
with return  compost of about 110%  in weight ratio to produce
a mixture  with a moisture content  of about 55%.   The mixture
is then charged into the  composting tanks.
The mixture  is turned over  once every other day,  reaches the
outlet of  the composting  tank after being subiected to the fifth
turnover,  and is finally  discharged from the composting tank.
The sludge cake is retained in the composting  tank for nearly
10 days.   The fermented sludge discharged from the composting
tank is classified through  3-mesh vibrating screen, and the
                                45

-------
          smaller  is  delivered  as  product  compost,  while  the  larger"  is
          used as  return  compost.
          The plant  is  oeprated to adjust  the moisture  content  of  product
          compost  to  30 to  35%.  Namely,  it  is required to  properly  adjust
          the ratio  of  return  compost  to meet the changes in  sludge  cake
          moisture content  and  fermentation  conditions.
          The aeration  of the  composting  tanks is carried out by air
          injected through  five blow pipes provided longitudinally in
          the bottom of the composting tank.   The standard  aeration
          rate is  set at  200 lit./m -sludge/min.   The aeration rate is
          adjusted while  monitoring the temperature rise in the composting
          tank.
               The product  compost is  packaged and delivered  in 20-kg
          bags.
       c.  Plant performance
               The composting plant was put  into commission in  May 1980.
          The achievements  from that time  till March 1981 were  as  follows.
          .  Sludge cake processed         :  1,271.4 tons
          .  Compost  production           ;    391.6 tons
          ,  Compost  shipments            :    367.7 tons
          .  Running  cost  (excl.          : ¥20,672/ton-sludge cake
            depreciation  cost)              v/._ ,,../
                                           ¥67,116/ton-compost
          The marketing route of product compost is as  shown below.
          A ton of product  compost fetches Sewage Works Bureau   ¥5,000.
               Tokyo Metropolitan  Government's Sewage Works Bureau ->
          Tokyo Metropolitan Economic  Agricultural Cooperatives ->- Local
          agricultural  cooperatives in Tokyo -> Farmers
2.2 SURVEYS ON THE AGRICULTURAL USE OF COMPOST
  2.2.1 Topics Discussed for Agricultural Use of Compost
             The Tokyo  Metropolitan Government organized a compost
        research and development project team in 1976.   Since then,  the
        team has undertaken a variety  of researches and studies.
        As regards the  matters concerning the agricultural effects of
        compost, safety,  demand and physical distribution, the surveys
        have been promoted under the leadership of the Bureau of Labor and
        Economic Affairs  in order  to study the following subjects .
                                   46

-------
     1) Soil-conditioning effects and fertilizing effect of compost.
     2) Compost application technology, and limitations on applications.
     3) Analysis of effective and toxic substances in compost.
     4) Formulation of compost merchandizing requirements and their
        indices.
     5) Compost demand, and marketing problems.
     6) Compost pricing.
     7) Other related matters.
      Each of these surveys is briefly described below.
2.2.2 Chemical Analysis for Preservation of Compost Quality and
      Assurance of Health Safety
           In Japan, sewage sludge compost for agricultural use is
      classified as a special fertilizer, and is subject to control
      according to the Fertilizer Control Law with respect to its heavy
      metal concentrations, etc.
           The limitations stipulated in the Fertilizer Control Law  are
      50 mg/kg for arsenic (As), 5 rag/kg for cadmium (Cd) and 2 mg/kg  for
      mercury (Hg).  In addition, the sludge compost is required to  meet
      the standards as specified in Table 1. (Refer to Table 1)

                       Table 1 Limitations on hazardous industrial wastes

1
2
3
4
5
6
7
8
Item
Mercury alkylides
Mercury or its compounds
Cadium or its compounds
Lead or its compounds
Organic phosphorous compounds
Sexivalent chromium compounds
Arsenic and its compounds
Cyanides
PCB
Criteria
Not detectable
Less than 0.005 mg per liter of sample liquid
Less than 0.3 mg-Cd per liter of sample liquid
Less than 3 mg-Pb per liter of sample liquid
Less than 1 mg-phosphorous compound per
liter of sample liquid
Less than 1.5 mg-sexivalent chromium
compounds per liter of sample liquid
Less than 1 .5 mg-As per liter of sample liquid
Less than 1 mg-cyanides per liter of sample liquid
Less than 0.003 mg-PCB per liter of sample
liquid
           The compost manufactured by the composting plant was examined
      according to these requirements.  In addition, an analysis to
      determine whether the denaturalization of compost is sustained during
      the  distribution process was conducted.
      a. Analysis  of  fertilizer components
                                   47

-------
         The  sludge cake, primary compost  (hot from the composting
    plant), heaped compost (primary  compost  cured for 45 days  in
    the open  air)  were subjected to  an  analysis of fertilizer
    components,  heavy metals, etc.
    The results  are as shown in Table 2.  (Refer to Table 2)

             Table 2  General characteristics and heavy metal content of compost
^^ Product
Characteristic'"'--^
Moisture content(%)
pH 
-------
                              Table 3 Results of storage tart
^^Chan>ct»ristic
Date 	 ^^\_
Jul. 21,1980
Nov. 10, 1980
Mar. 31,1981
Moisture
content (%)
34.35
34.22
34.08
Ignition
loss(%)
37.56
36.90
35.16
T-N
<*)
•2.25
2.10
2.10
T-C
(%)
19.39
18.86
18.70
*PH
(H,0)
7.71
7.93
7.82
"pH
(KCt)
7.93
8.00
7.99
•EC
(mil/cm)
4.89
5.34
5.38
•COD
(ppm)
2,120
1,940
1,910
"NH4-N
(mg/1008)
497
648
645
"NOj-N
(mg/IOOg)
6
N.D
jtrace
  Notes: 1. Ignition loss, T-N, and T-C refer to dry compost.
      2. The characteristics marked with an asterisk refer to mixture of 1 part of dry compost and 10 parts of water.
        Those marked with two asterisks refer to a mixture of 1 part of compost and 10 parts of KCE (10% solution).

         During  the eight and a half month  storage period,  little change
         occurred in moisture content and pH value.   The  ignition loss,
         T-N,  T-C,  and COD decreased a  little, while the  electric
         conductivity (EC) and NH.-N increased slightly.  While  fermenta-
         tion  was still in progress, this was  not so violent as  to  cause
         denaturalization.
      c. Mineralization test
               A  sample of compost was sieved through a 1-mm screen,  and
         a 10  mg N  equivalent was mixed with 50 g of dry  soil.   The
         mixture was  then cultured for  100  days at a temperature of  29
         to 30°C with its moisture content  controlled at  50 to 60% of
         the maximum water holding capacity, for the purpose of  examin-
         ing the changes:in inorganic nitrogen content.
               It was  found that the primary compost  originally contains
         inorganic  nitrogen accounting  for  20% of its total nitrogen,
         is easy to nitrify and decompose,  and has an immediate  effect
         as a  fertilizer.
2.2.3 Tests on Application Effects and  Safety
      a. Application to vegetables
               Since 1978,  the growing of Japanese radish  for spring
         cropping and cabbage for autumn cropping has been  tested at
         the Kurohoku Ominous soil containing  volcanic ash) soil farms
         of the  Agricultural Experiment Station.
               For two years after the start of the tests, efforts were
         made  to study the fertilizer effects  of compost.   Now a study
         of the  effects of continued application of  compost on the crops,
         particularly regarding accumulation of lime in the soil, has
         keen  under way.
                                       49

-------
                With respect to  the fifth spring  crop of  Japanese radishes
           and the  sixth  autumn  crop of  cabbages,  an outline of  test
           farms, yield  from each  farm,  and an  analysis  of edible parts
           of the crops  for heavy  metals, etc.  are shown  in Tables 4,  5
           and 6.   The transition  of yields from  the first and  subsequent
           crops  is shown in Table 7.  (Refer  to Table  4,  Table  5, Table 6
           and Table 7)
                                  Table 4  Test sections
                                                                        (kg/10a)
\ Crop and ferti-
\lizer application
Section \
Control section
(chemical ferti-
lizer section)
1 -ton compost
plus chemical
fertilizer section
1 -ton compost
without chemical
fertilizer section
1 -ton heaped
compost section
Japanese radish for spring crop (5th crop)
Chemical fertilizer
as starter
N
15
15
-
15
P20,
25
25
25
25
K20
15
15
15
15
Chemical
fertilizer as
top dressing
N
10
10
-
10
KjO
10
10
10
10
Calcium
carbonate
283
-
-
-
Compost
-
1,000
1,000
1,000
Cabbage for automn crop (6th crop)
Chemical fertilizer
as starter
N
15
15
-
15
PaO,
30
30
30
30
K20
10
10
10
10
Chemical
fertilizer as
top dressing
N
10
10
-
10
K,0
10
10
10
10
Calcium
carbonate
386
-
-
-
Compost
-
1,000
1,000
-
Note:  1 ton of dry compost contains 23 kg of N and 32 kg of P2 05, and 1 ton of dry heaped compost contains 22 kg of
     N and 35 kg of P2 0,.
                              Table 5 Yields from the test sections
                                                                            (1980)
^^-^^Crop and survey item
"~-^^
Section ~ ~~\^
Chemical fertilizer section
1 -ton compost plus chemical
fertilizer section
1 -ton compost without nitrogen
chemical fertilizer section
1 -ton heaped compost section
Japanese radish spring crop (5th crop)
Total
weight
per plant
9109
845

788

942
Per plant
total weight
index
100
93

89

104
Root
weight
per plant
3439
332

372

365
Per plant
root weight
index
100
97

108

106
Cabbage for autumn crop (6th crop)
Total
weight
per plant
2.61*9
2.59

21-3

2.53
Per plant
total weight
index
100
99

82

97
Head
weight
per plant
1.51k9
1.47

1.17

1.38
Per plant
head weight
index
100
97

77

91
                    Table 6 Content of heavy metals, etc. in edible parts of crops (ppm)
                                                                            (1980)
— - 	 	 Chemical composition
Crop 	 	 	 __

Japanese
radish
for
spring crop
(5th crop)



for
autumn
crop
(6th crop)

Chemical
1 -ton compost plus chemical
fertilizer section

1 -ton compost without nitro
gen chemical fertilizer section
1-ton heaped compost section
Chemical fertilizer section
(control section)

1 -ton compost plus chemical
fertilizer section
1-ton compost without nitro-
gen chemical fertilizer section
1 -ton heaped compost section
N03

1,890
1 970


1,890
2,080
1,440

1,490
830
1,260
As

less than
0.1



"
"
less than
0.1

"
-
"
Pb

less than
0.1



"
"
less than
0.1

••
••
"
Cd

less than
0.1
..


"
"
less than
0.1

"
••
"
Zn

1.63
1.73


1.30
1.77
1.77

1.67
1.57
1,80
Cu

0.37
0.27


0.33
0.37
0.57

0.53
0.40
0.27
Cr

less than
0.1
..


"
"
less than
0.1

"
••

Hg

less than
0.01



"
"
less than
0.01

"
••

                                        50

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             Table 7 Transition of yield index during farm tests
^ Crop and year
~~ ~~^ of survey
Section ~~~--^
Chemical fertilizer section
1 -ton compost plus chemi-
cal fertilizer section
1 -ton compost without
nitrogen chemical fertilizer
section
1 -ton heaped compost
section
197
Japanese radish
spring crop
100
109
103
96
8
Cabbage
autumn crop
100
102
107
96
19
Japanese radish
spring crop
100
90
86
96
79
Cabbage
autumn crop
100
104
108
93
19
Japanese radish
spring crop
100
97
108
106
BO
Cabbage
autumn crop
100
97
77
91
      The results  of  the first two years of operation show that
 all  the crops  but the  third spring crop of Japanese radishes
 yielded more than those grown on chemical fertilizer alone,
 and  that  the use  of  compost  to  supplant  nitrogen  fertilizer
 also  produced  a high yield.
      The  test  results  for the year  1980  show  that  the compost
 farms were a little  inferior  in yield  to  standard  chemical
 fertilizer farms.
      It is inferred  that this decline  in  yield may have  been
 invited by the lime  contained in  compost,  and that the yield
will be increased  if the application of  compost is reduced.
When  the  heaped compost was used, all  the crops but the  spring
 crop of Japanese  radishes in  1980 were lower  than  the chemical
 fertilizer-grown  counterparts, and  a further  study will  be  needed
 in this respect.
     The  intake of heavy metals by  the plants was  studied.
 In the first year of compost  application,  the concentrations
of copper and  zinc in  the crops rose a little.
 In the second  year, however,  there  was no  noticeable rise in
heavy metals such as those shown  in Table  6.  The  concentration
of nitrate rose a little, but fell  off when nitrogen fertilizer
was eliminated. (Refer to Table 6)
     An analysis of soil from fallow land  showed no accumulation
of copper, zinc and nickel.   As regards the nutrient balance
of soil,  the application of compost gradually increased  ex-
changeable calcium and potassium, but  decreased magnesium;
namely, the magnesium/potassium ratio  and  the magnesium/calcium
ratio became low, making the  soil susceptible to magnesium
                          51

-------
    deficiency.   In future, measures will have to be provided to
    supplement magnesium.
        According to experiments on spinach, it was found that
    N and P  in compost showed an effectiveness of 50 to 60% and
    about 30% respectively as compared with the corresponding
    chemical fertilizers.
        Namely,  a ton of dry compost per 10 a is expected have
    an effect equivalent to about 10 kg of nitrogen fertilizer
    and about 10  kg of phosphate fertilizer.  As the compost is
    destitute of  potassium, potassium must be made up in the form
    of chemical fertilizer.
b. Application of compost  to orchards
        A compost application test was conducted on Japanese
   pears,  Japanese apricots, and Japanese chestnuts in the
   Agricultural Experiment Station and also on Japanese pears grown
   by commissioned farmers.
        In the Agricultural Experiment Station,  three farms were
   prepared:  a control farm using chemical fertilizer only; a
   pH-conditioned farm using chemical fertilizer and calcium
   carbonate;  and a compost farm using 2 tons of compost per 10 a
   and chemical fertilizer to supplement nitrogen and potassium.
        The commissioned farmers used a control farm using chemical
    fertilizer, and a compost farm using 2 tons of compost per 10 a.
   The fertilizing effect of compost on each tree species was
   correlated with the yield index as shown in Figure 2.
   (Refer  to Fig. 2)
                             52

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      150T
Yield index

      100-
      50
             Japanese pear    Japanese pear    Japanese pear     Japanese apricot
                         (by commissioned  (by commissioned
                         farmers)       farmers)
                                 Japanese chestnut
             I   1
                 o
                 •«=
                 '•5
                 c
                 o
                 V
                 I
                 a
3
o
o
K
a
o
o
                  S   ~S
8
o
S
|
3
                                                                       I
                                                                       G
                                                                       S
                      i
                      CL
O
V
I
                              Fig. 2 Fertilizing effect of compost
               The  crop  of Japanese chestnuts  increased by about 30%,
          followed  by  Japanese pears and Japanese apricots with an
          increase  of  about 10% each.  The application of compost brought
          about no  change in the nitrogen concentration in the leaves  of
          Japanese  chestnuts,  but a slight increase  in nitrogen concent-
          ration was noticed in the leaves of  Japanese pears and Japanese
          apricots, suggesting that too much nitrogen was supplied.
               If the  compost  application is moderated, the yield will
          be increased more.
               As regards the  quality of fruits,  the application of
          compost slightly increased N, P, Ca,  and Zn in Japanese
          apricots, but  the concentration levels  of  other inorganic
          substances, heavy metals, nitrate, etc.  remained the same as
          they were before application of compost.   The total amount of
          sugar, glucose, sorbitol, and sucrose,  etc.  tended to rise,
          improving the  quality of the fruits.
               The same  tendency was seen in the  Japanese chestnuts;
          the total amount of  sugar, fructose,  and glucose increased
                                        53

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         while sucrose and starch declined, improving the commercial
         value of chestnuts as a whole.  As regards Japanese pears,
         however, no substantial improvement in quality was noticed.
         The quality of Japanese pears will be improved by reducing
         the supply of nitrogen, however.  An analysis of toxic sub-
         stances, such as heavy metals, contained in the pears is shown
         in Table 8. (Refer to Table 8)
                         Tables Chemical analysis of Japanese pear
                                                                      (in ppm)
Section
Compost section
pH-conditioned
section
Control section
N P K Ca Mg
0.397 0.042 0.900 0.034 0.042
0.393 0.037 0.766 0.033 0.034
0.439 0.039 0.888 0.031 0.041
Pb Cu Zn Cr Cd Hg As
0.1 0.4 0.7 less than less than less than less than
0.1 0.1 0.1 0.1
less than less than less than less than
0.1 0.3 0.5 0.1 0.1 0.1 0.1
Nitrate
6
8
2.2.4 Use of Compost by Farmers
           The farmers in Tokyo were entrusted with the task of growing
      vegetables such as cabbage, spinach, and cauliflower on compost.
      In the main, the compost worked well, and the opinions of the
      commissioned farmers were favorable.
           The results of the growth of cabbage and spinach on compost
      are given below.
      a. Cabbage
              Compost was applied to a farm overworked by twice annual
         cropping for more than 20 years, and its effects on cabbage
         growth were studied.
         The farm was divided into three sections:  A control section
         using chemical fertilizer alone; a 1-ton compost section  using
         a ton of compost per 10 a, together with chemical fertilizer;
         and a 2-ton compost section using 2 tons of compost.  The
         yields and the incidence of plant diseases are shown in Table  9.
         (Refer to Table 9)
                                  54

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                          Table 9 Survey of yields and incidence of diseases
~^\^ Item
Section ^~^

Control section
1-ton compost section
2-ton compost section
(a) Yield
Per head
average

1.33 k9
1.44
1.35
Total weight
per 10 a

5,990k9
6,460
6,050
Index

100
108
101
(b) Incidence of black rot
Extremely
high

16
0
1
High

24
3
• 4
Medium

8
10
8
Low

2
36
35
None

0
1
2
Damage
index

77
33
34
Notes: (1) In the yield survey, 20 heads were sampled from the middle row of each section and weighed.
     (2) The morbidity was investigated by sampling 50 heads from the middle row of each section according to the following criteria.
       Extremely high::  Head affected
       High       :  Leaves affected
       Medium     :  All the external leaves affected
       Low       :  Part of external leaves affected
       None       :  No part affected


               As  is  clear from Table 9,  the 1-ton  compost section showed

          the highest yield,  and the compost sections were generally

          lower in the incidence of  black rot  than  the  control  section,

         warranting  the application of  compost.

      b.  Spinach

               A farm debilitated  by overcropping and oversupply of

          chemical fertilizer was  selected  in  order to  examine  the

          effects  of  compost  on spinach.   Just as with  cabbage,  the farm

         was divided into:

         A control section;  a 1-ton compost section using a  ton of

          compost  per 10 a,  together with chemical  fertilizer;  and a

          2-ton compost section using 2  tons of  compost per 10  a.

         The growth  conditions and  yields  were  investigated.   The results

         are shown in Table  10. (Refer  to  Table  10)


                    Table 10 An example of investigation of agricultural use for spinach

Control farm conditioned
with chemical fertilizer
Farm using compost
(1 ton per 1000m1)
Farm using compost
(2 tons per 1000m3)
Investigation of growth and harvest (1st harvest)
Study of grwoth
Length of blade
21.5 (cm)
24.0
22.3
Width of blade
49 (cm)
5.3
5.4
Number of blade
6.3 (blades)
7.3
7.8
Study of harvest
Total weight
0.85 
1.45
1.35
Adjusted weight
0.74 (kg)
1.29
1.22

ratio
100
174
165

Control farm conditioned
with chemical fertilizer
Farm using compost
(1 ton per 1000m1)
Farm using compost
(2 tons per 1000m1)
Investigation of growth and harvest (2nd harvest)
Study of growth
Length of blade
22.1 (crr^
24.2
23.2
Width of blade
7 2 (cm)
7.6
7.3
Number of blade
104 (blades)
10.2
9.9
Study of harvest
Total weight
0.80 (k9l
1.00
0.95
Adjusted weight
0.71 
0.91
0.85
Ratio
100
128
120
                                         55

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              As demonstrated in Table 10, the compost sections out-
         performed the control section in both growth and yield.
              In the 1-ton compost section, the first crop showed a
         yield increase of 74% in terms of adjusted weight, and the
         second crop 28%.  The quality of the crops raised in the
         compost sections was also better.
              An analysis of fallow soil indicated that the soil which
         was pH 5.12 before application of compost was improved to pH
         5.61 in the 1-ton compost section and to pH 6.28 in the 2-ton
         compost section, proving that compost is highly effectix'e in
         improving acid soils.
              The rise in electric conductivity was also low.
         It is therefore concluded that this degree of compost
         application will not aggravate the concentration hazards.
2.2.5 Quality and Application Standards for Compost
           According to the results of the compost application tests
      detailed in the foregoing, a quality standard and an application
      standard were formulated.  20 kg bags of compost are labeled
      with these standards as follows.
      a.  Quality and safety
              The compost is quite safe from arsenic, cadmium, mercury
         and other heavy metals, (The quality of the compost is as shown
         in Table 11) (Refer to Table 11)
                            Table 11 Compost quality labeling
Nitrogen
1 -1%
Phosphate
2-3%
Lime
16- 18%
pH
7-8
Organic matter
20 - 30 %
Moisture content
30 - 35 %
      b. Features and usage
              This fertilizer is made of dewatered domestic wastewater
         sludge of the Tama New Town, fermented for about 10 days.
         It contains lime and nitrogen, and is effective as a fertilizer
         and a pH improver.
         i. Highly effective in curing acidosis, a ton of this
            fertilizer is equivalent to 300 kg of calcium carbonate.
        ii. The nitrogen component contained in a ton of this fertilizer
            is equivalent to about 50 kg of ammonium sulfate.  This
                                    56

-------
               fertilizer  retains  fertilizing  effectiveness  for  an  ex-
               tended period.
          iii.  This fertilizer contains  no  potassium.
               Supplement  potassium as required.
           iv.  This fertilizer contains  organic  substances by  20 to 30%,
               and  should  preferably be  used in  combination  with manure or
               other organic  fertilizer  for enhanced  fertilizing, effeciency.
            v.  Apply this  fertilizer at  a rate of within 1  ton per  10 a.
               Mix well with soil, and wait several days before planting.
           vi.  If you have any questions, do  not hesitate to contact your
               local Agricultural  Improvement  and Diffusion  Center.
3.  PRODUCTION OF ARTIFICIAL LIGHTWEIGHT AGGREGATE, USING SEWAGE SLUDGE ASH
        So far, the Tokyo  Metropolitan Government has disposed of sewage
   sludge by dumping.  But available dump sites have been decreasing
   rapidly.  In addition,  the dump sites are  problematic from the viewpoint
   of environmental safety.   Concerned over these problems,  the Tokyo
   Metropolitan Government has promoted  a project for disposal of sewage
   sludge in the form of ash-
        In the future, the installed capacity of incinerators will  be
   increased, and the volume of ash to be generated will accordingly rise.
   A survey was thus conducted to  determine ways in which the ash could
   be utilized.
        After evaluating the various conceivable products from various
   angles, including the energy necessary for production, added values of
   products, potential demand and  environmental safety, the production of
   artificial lightweight  aggregate was  considered one of the quickest
   and simplest approaches to recycling of sewage sludge ash. Outlined
   below are the perspective of the industrial manufacturing through the
   development of this manufacturing technique.
 3.1 ARTIFICIAL LIGHTWEIGHT AGGREGATE
          The artificial lightweight aggregate currently available on the
     market is made of sedimentary rock or shale either crushed to appropriate
     sizes or pulverized and pelletized, and  then sintered at 1,000°C to
     about 1,200°C.
          Shale is also called mudstone, and  is an incomplete agglomeration
     of clay.  It is mainly composed of silicon and aluminum, and  contains
                                   57

-------
    volatile matter that is dissipated at high temperatures.
    It  is light  and fragile.
         When shale is sintered under proper conditions, silicon and
    other elements become semi-fused and softened, and at the same time,
    volatile matter is gasified to make the stone intumescence.
         When cooled,  the pieces of shale become a hard and tough
    aggregate, with a  finely-textured glazed shell on the outside and a
    finely pored nest  inside. (Refer to Photograph)
              Photo.   Artificial lightweight aggregate made of sludge ash
                      (independent pores are seen inside.)
         The specific gravity of this artificial lightweight aggregate  is
    about 1.4, or about half that of natural aggregate.
3.2 USE OF SEWAGE SLUDGE ASH AS ARTIFICIAL LIGHTWEIGHT AGGREGATE
         Compared with shale,  the chemical composition of the sludge  ash
    varies widely depending on the types and quantity of coagulants inject-
    ed for the purpose of dewatering the sludge.
         This is particularly so in the case of the ash of  sludge  cake
    dewatered with inorganic coagulants, which shows a high variation
    in the lime content.  Compared with shale, the ash of sludge cake
    dewatered with polymer or by heat treatment or by freezing  and
    defrosting,  contains more lime and ferric oxide, but  less silicon.
    The amount of volatile matter that serves as a foaming  agent is
    less in the ash than in shale. (Refer to Table 12)
                                   58

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                        Table 12 Chemical composition of samples (%)
Chemical
composition
SiO2
P30S
Al,0,
Fe,03
FeO
CaO
MgO
KjO
Na,O
SO3
Cl
C
CO,
Ign-loss
Ash A
(Coagulant: Lime
and iron chloride)
29.86
5.41
11.18
11.09
1.22
25.19
1.86
0.89
0.81
2.92
0.59
1.08
3.51
5.60
AshB
(Coagulant:
Polymer)
55.6
2.51
18.48
10.48
1.84
4.28
2.67
1.64
1.54
0.69
—
0.77
0.13
1.67
Expansive shale
(ore available
from company A)
64.30
—
16.34
1.36
3.23
1.20
1.23
2.55
1.94
0.65
—
0.66
1.75
7.34
Expansive shale
(ore available
from company B)
62.14
—
15.42
3.07
2.30
2.46
2.04
1.74
1.59
0.10
—
0.27
0.61
8.74
Bentonite
71.07
—
14.21
1.60
0.04
1.52
2.30
0.44
2.16
0.01
_
—
—
5.94
 Note: " — " denotes less than 0.00.

         In general, it was surmised that it would be  feasible  to  convert
    sludge ash. obtained without lime injection into artificial  lightweight
    aggregate.
3.3 SINTERING OF SLUDGE ASH INTO ARTIFICIAL LIGHTWEIGHT AGGREGATE
         Sludge ash containing large amounts of lime shows a high  melting
    point, and its fusion shows a low viscosity, whereas sludge ash
    with less lime has almost the same melting temperature and  viscosity
    as shale.
         So far as the practical sintering temperature (approx. 1,150°C)
    is concerned, the lower the lime content in the sludge ash, the
    better.   What makes the sludge ash quite different from shale  is
    the fact that the viscosity of a dough made up of  sludge ash powder
    and water is far below that of shale, and the strength of dry  pellets
    is far below that of shale.
    Namely,  the pellets are turned into powder as they cannot hold their
    shapes when sintered in:the kiln.  It is therefore necessary to use  a
    proper binder for the purpose of increasing the strength of pellets.
    The sludge ash is deficient in volatile matter either in the form  of
    organic or inorganic substance as it has been sintered at a tempera-
    ture of  800°C to 900°C, and is not able to intumesce enough at heat.
                                     59

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     To counteract these problems,  it  is necessary to select an additive
which.serves not only as a binder but  also as a foaming agent.
Shale and hentpnite combine  the binding power with the foaming power,
and can solve these problems.
     When bentonite or  shale is used as a foaming binder, the relation-
ship between the process  flow (Figure 3) and production requirements
is as follows.  (Refer to Fig.  3)
II Ash of sewage sludge
1
t
Pulverization



I

Shale jj or

Drying
i
Pulverization
*


Mixing and
moisture control
i

Pelletization


I Bentonite |
\
t
Slurrey



                                 Drying
                                Sintering
                                 Product
                 Fig. 3 Process flow of artificial lightweight aggregate

a. When  bentonite is used:
         When added with water, bentonite becomes highly  adhesive,
   making the pelletizing of sludge ash easy.  When  sintered,  the
   pellets puff up.   Both intumescibility and distensibility increase
   with  increase in the addition of bentonite as shown in Figure 4.
   (Refer to Fig.  4)
                                  60

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    1.8
 $  1.6
 m
 k.
 O)
 o
 "5
 V)
 .0
    1.2
    1.0
   0.8
Sintering time: 20 min.
 • Sintering temperature: 1,140°C
 O Sintering temperature: 1,150°C
                                           6             8            10
                                  Bentonite addition (%)
                        Fig. 4  Relationship between bentonite addition
                              and absolute dry specific gravity
   The best results are obtained under the  following conditions.
   . Sintering temperature          :  1,140°C  to 1,150°C
   . Sintering time                 ;  15  to 20 min.
   . Addition of bentonite          :  4 to  6%
b. When  shale is used:
         Bentonite is costly,  and can be substituted satisfactorily
   by shale (expansible shale)  which has  long  been the material  for
   artificial lightweight aggregate.  When  the addition of shale is
   increased, the specific  gravity of sintered pellets becomes  small
   as shown in Figure 5.  (Refer to Fig. 5)
                                   61

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                                    15       20       25       30
                              Addition of expansive shale (%)

               • Sintering temperature: 1,140°C
               o Sintering temperature: 1,150°C

                     Fig. 5  Relationship between addition of expansive
                           shale and absolute dry specific gravity


     With the  addition of  shale fixed  at 15%  and  20% and  the sinter-
ing  temperature  fixed at 1,150°C,  the  specific gravity  decreasing
with sintering time as shown  in Figure 6.  (Refer to  Fig.  6)
                                  62

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                                            Sintering temperature: 1,150 C
0.8
                                       20
                                  Sintering time (min.
                • Addition of expansive shale: 1 5%
                o Addition of expansive shale: 20%

                       Fig. 6  Relationship between sintering time and
                              absolute dry specific gravity of expansive
                              shale-added pellets

      A  similar trend is  also  seen  in bentonite  as shown  in Fig.  7,
(Refer  to Fig.  7)
                                       63

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 CO
 k_
 O)
 o
  O
  (A
 .0
     1.8
     1.6
     1.4
 »   1.2
     1.0
     0.8
Sintering temperature: 1,150°C
•  Bentonite addition: 5%
O  Bentonite addition: 6%
            15
10                 20
        Sintering time (min.)
                 25
30
                           Fig. 7  Relationship between bentonite addition,
                                  sintering time and absolute dry specific
                                  gravity

           The quality  of sinter and the  physical  test  results of  con-
      crete  are as  shown in  Table  13,  14, and 15.
      (Refer to Table 13, Table 14  and  Table  15)

                 Table 13  Physical properties of artificial lightweight aggregate
^"~"-\^^ Type
Characteristics ^^~\^^
Nominal dry specific gravity
Absolute dry specific gravity
Hygroscopicity (%*
Unit weight (kg/m3 )
Solid volume percentage (%)
Ratio of floating particles
in coarse aggregate (%)
10% crushing value*(tons)
Aggregate shock value (%)
Wear loss (%)
Fine aggregate
Commercially
available
fine aggregate
1.85
1.69
9.9
1,079
-
-
-
-
-
Coarse aggregate
Ash aggregate
(LA)
1.26
1.24
1.3
789
63.6
1.7
9.1
35.4
28.4
Commercially
available palletized
aggregate (LB)
1.33
1.23
8.1
806
65.5
0.3
13.1
33.8
25.5
Commercially
available non-
pelletized aggregate
1.47
1.36
8.4
881
64.8
1.8
16.2
25.4
18.2
*: Load required to crush 10% of aggregate.
                                          64

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                           TeMa 14 Concntt mix prapartkmi
Type

L,


IB

Maximum size
(mm)
15
15
IS
15
15
15
Stump
(cm)
7.5
5.5
5.6
14.0
6.5
7.5
Air volume
(XI
6.5
7.2
8.3
6.2
7.1
10.1
Water to
cement ratio
(W/C*)
40
50
60
40
50
60
Unit water
weight
(kg)
149
149
150
150
150
150
Unit cement
weight
(kg)
373
298
250
375
300
250
Sand
percentage
(%)
46.0
47.0
50.5
44.0
46.5
48.5
Fineaggre.
gate weight
(kg)
58S
618
678
558
611
652
Coarie aggre-
gate
(kgl
462
468
446
549
543
535
Admixture
(kg)
0.933
0.745
0.625
0.938
0.750
0.625
Unit weight
(kg/m' )
1632
1578
1552
1647
1619
1581
                       Table 15 Strength, elastic modulus and ttrength ratio
Item

Compression strength
kgf/cm'

Bending strength
kgf/cm'

Tensile strength
kgf/cm1

Static modules of
elasticity
xlO4 kgf/cm'

Dynamic modulus
of elasticity
xlO" kgf/cm'
W/C

40
50
60
40
50
60
40
50
60
40
50
60
40
50
60
Skimp

7.5
6.5
5.5
7.5
5.5
5.5
7.5
5.5
5.5
7.5
5.5
55
7.5
55
5.5
Air
%
6.5
7.2
8.3
6.5
7.2
8.3
6.5
7.2
8.3
6.5
7.2
8.3
6.5
7.2
8.3
UA aggregate concrete
7 days
278
150
98
-
-
-
—
-
_
-
—
-
_
-
28 days
375
240
169
46.2
42.4
30.6
30.7
24.5
18.4
16.3
13.5
12.5
17.6
15.8
13.4
91 days
424
294
233
52.7
51.7
391
31 1
29.7
23.6
_
-
-
-
_
-
W/C
%
40
50
60
40
50
60
40
50
60
40
50
60
40
50
60
Skimp
cm
14.0
6.5
7.5
14.0
6.5
7.6
14.0
6.5
7.6
14.0
6.5
7.5
14.0
6.5
7.5
Air
%
6.2
7.1
10.1
6.2
7.1
10.1
6.2
7.1
10.1
6.2
7.1
10.1
8.2
7.1
10.1
L, aggregate concrete
7 days
274
215
110
-
-
-
:
-
_
-
-
_
„
-
28 days
395
316
169
47 3
43.2
29.4
28.6
27.2
21.2
13.6
13.4
11.9
17.0
14.4
13.2
91 days
448
400
210
52.6
490
34.8
31.8
28.8
21.7
_
-
—
_

-
Strength ratio, L«/LB
7dey»
1.01
0.70
0.89
-
-

-
_
_
- -
-
_

-
28 days
0.95
0.76
1.00
0.98
0.98
1.04
1.07
0.97
0.86
1.13
1.01
1.05
1.05
1 10
1.02
91 days
095
0.74
t.II
1.00
1.06
1.12
0.98
1.03
1.09

-
_
_

-
c. Others
        As previously mentioned,  the ash of sewage sludge contains
  •more lime and ferric oxide  than  shale.   These compounds reduce
   the viscosity of the vitreous  phase,  narrowing the sintering
   temperature range.  But when shale and sludge ash are pulverized
   to finer than 200 meshes, the  mix proportion of shale can be
   reduced to as small as 30%  without sacrificing the sintering
   temperature stability.  In  addition,  the variation in specific
   gravity and strength of the sinter decreases.
        If unpulverized sludge ash  is used, it is difficult to
   industrially produce merchandizable sinter unless the mix pro-
   portion of shale is increased  to as much as about 70%.
        These results have been obtained through sintering tests
   using a pilot kiln and a production kiln.
                                  65

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3.4 PROPOSED RESEARCH
         Thanks to the current state  of  the art  in sintering,  the
    industrial production of artificial  lightweight aggregate  from sludge
    ash has now become possible.   Many technical improvements  for  the
    purpose of saving energy are  still required, however.
    The waste heat developed in the  system must  be recovered to  a  maximum
    extent; it will be used effectively to dry pellets  containing  a great
    amount of water.   In addition, the sintering method must be  improved
    and the amount of additives must  be reduced.
         Although the efforts have so far been expended to study the
    conversion of sludge ash into artificial lightweight aggregate,  the
    high calorific value of sludge cake may make it possible to  develop
    a system in which the incineration of sludge and the production of
    artificial lightweight aggregate  can be carried out concurrently.
         In view of this, we are  planning to study processes that  will
    directly turn sludge cake to  good account.
         The recycling of sewage  sludge within a city will eliminate the
    problem of transporting sludge out of the city and  at  the  same time
    will reduce the amount of resources  to be brought into the city from
    outside.  Sewage sludge may become a valuable resource if  developed.
    It may be used as a material  for  slag cement and slag brick, etc.
    We would like to gradually implement sludge  recovery measures  which
    will be feasible and viable not  only at present but in the future.
                                    66

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                                      Eighth US/JAPAN Conference
                                                on
                                      Sewage Treatment Technology
EXPERIMENT  ON  INCINERATION OF MUNICIPAL REFUSE
           AND SEWAGE SLUDGE IN  KYOTO CITY
                        October 12, 1981
                         Cincinnati, USA
       The  work described in  this paper was  not  funded by the
       U.S. Environmental Protection Agency.   The contents do
       not  necessarily reflect the views of  the  Agency and no
       official endorsement should be inferred.
                         Takashi Yoneda
                           Director,
                      Sewage Works Bureau,
                           City of Kyoto
                               67

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1.   PREFACE
1.1  CURRENT  STATUS  IN KYOTO CITY
     Kyoto City is located on the middle of the Yodo River and is an inland city
surrounded by hills on three  sides with a  population of 1,460,000. The Yodo River
is water resources for about  11 million people  downstream in the Osaka-Kobe dis-
trict. Consequently, the  construction  of sewer system in this city is important for
the preservation  of water quality in the Yodo River. The sewer network of Kyoto
City covers 60.2% of its  total residents as of April 1981. Influent to the wastewater
treatment plants is discharged into the Yodo River through the secondary treatment.
All of sludge produced is thickened, partly digested, and dewatered. For the volume
reduction and stabilization, dewatered cake is  all incinerated and landfilled or the
municipal disposal site.
     The current ash disposal site has a limited area of about 4 ha for landfill. It is
difficult to secure the new  site. With the progress of the sewerage construction the
quantity  of sludge produced is expected  to increase more and more in the future.
So the treatment and disposal of sludge have become an important problem.
1.2  IDEA  OF   COMBINATION  OF  WASTEWATER   TREATMENT PLANT
     WITH MUNICIPAL REFUSE  INCINERATION PLANT
     Wastewater and refuse  are representatives of municipal wastes, whose treatment
and disposal consumes various types of energy  enormously. The energy flow in the
treatment system for wastewater and municipal refuse is shown in Fig. 1.
         Fig. 1 Energy Flow in Treatment of Municipal Wastewater and Refuse
                                  68

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     Note the waste water  treatment  plant and the  municipal  refuse incineration
 plant in the dot line in Fig. 1. The former plant consumes electric power for blower,
 pump and other  machines in the wastewater  treatment  process  and for various
 machines in the sludge thickening, dewatering ;md incineration processes. Heavy oil
 is also utilized mainly as auxiliary fuel for incinerator. In case that digestion process
 is well operated, it is possible to recover energy as digestion gas, which is used both
 for heating the digestion tank and for auxiliary fuel of incinerator.
     The total energy consumption at the  wastewater treatment plants in Kyoto
 City (converted into electric power) was about 0.66 kWh/m3 influent in fiscal 1980.
 Digestion gas covered about 18% of the entire energy consumption. As mentioned
 above,  a huge quantity of energy is required  for pumping, wastewater treatment
 and sludge  treatment at  the plant. It may be called an energy-consuming  plant.
     On the other hand,  the  low heat value  of municipal  refuse is about  1,500
 Kcal/kg at the municipal refuse  incineration plant. About  180 kWh/ton refuse is
 generated in general  with thermal energy produced  by incineration although the
 efficiency depends on the generation  system.  As electric  power  required at the
 incineration plant  is about 60 kWh/ton refuse,  about 120 kWh/ton  refuse is surplus
 electric power. That  is, the municipal  refuse incineration plant  may be called an
 energy producing plant.
     On the assumption  that  the wastewater  treatment plant  and the municipal
 refuse incinerator are combined in one  system as shown  in Fig. 1,  the  latter is
 capable of supplying  surplus energy to the  former  as electric power or steam. The
 idea of combination is illustrated in  Fig. 2 with the mutual utilization of treatment
 facilities as well as energy.
                                LJcctnc or Thermal Energy
                       Refuse
                       Incineration
                       Plant
                                   VVastewattr
                                Sludge, Screenings
                     Fig. 2 Combination of Wastewater Treatment
                          Plant and Waste Incineration Plant
     About 60~70% of dry solids of sewage sludge is combustibles (organic matter).
By  reducing  fully the water  of sludge and lowering  the latent heat of moisture
evaporation, its low heat value will become similar to that of municipal refuse, and
it will be combustible without  auxiliary fuel or be incinerated with municipal refuse.
On  the other hand, wastewater produced in the  municipal refuse incineration plant
will be treated at the wastewater plant when the toxic substances like heavy metals
to the biological treatment is removed in the pretreatment.
                                      69

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     The  combination of the two  plants will save the construction cost and the
maintnenace  and  operation  cost including energy  consumption. The feasibility
study of the abovementioned combination has been conducted, as a construction
plan of the Ishida plant, the fourth  in Kyoto and that  of a municipal refuse incine-
rator adjacent to the former were ongoing simultaneously.
     This  report presents  the  results of investigation conducted in 1977-1979 to
evaluate the feasibility of  sewage sludge incineration by the municipal refuse incine-
rator, especially with attention to the pretreatment of sewage sludge and its charac-
teristics.
2.   CONSTRUCTION  PLAN OF  WASTEWATER  TREATMENT PLANT AND
     MUNICIPAL  REFUSE INCINERATION PLANT
     A plan of the Ishida  plant of the Sewage Works Bureau and the Higashi Refuse
Incineration Plant of the Cleaning Bureau is shown in Table 1. Fig. 3 shows the lay-
out of two plants. As the  vicinity of the  plants is an exclusively residential district,
several pollution preventives are taken into consideration. As there has been no plant
operated for coincineration of sewage sludge and municipal refuse  in Japan, the
feasibility study was conducted.
                    Ishida Wastewater Treatment Plant
                                                   Higashi Refuse Incineration Plant
                   Proposed Site tor
J. Tank
r 	 |
Sludge Treatment Facilities

	

Wastf
Facili
Final
Sedimen
tation
Tank


water Treatmen
ies
Aeration
Tank



Primary
Sedi-
men ta-
tion
Tank


_j [
|
Machine
House

d,i ir
Purnpin
Station
|Grit
ICham-
I ber
  Fig. 3 Ishida Wastewater Treatment Plant and Higashi Refuse Incineration Plant
                                     70

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     Table 1  Plans for Ishida Sewage Treatment Plant and Higashi Refuse Incineration Plant
Ishida Sewage Treatment Plant
Plant Site Area
Design Sewer Service
Area
Design Population
Served
Design Flow of
Influent (Day Max.)
Collection System
Wastewater Treat-
ment Process
Sludge Produced
Sludge Treatment
Process
87,600m2
1 ,984 ha
230,900
163 ,000m3 /day
Separate
Conventional Acti-
vated Sludge Process
28t DS/day
(VS: 70%)
Incineration with
Municipal Refuse
Higashi Refuse Incineration Plant
Plant Site Area
Type of Incinerator
Capacity
Burning Temperature
Low Heat Value of
Refuse
Unburned Content in
Ash
Waste Heat Boiler
Independent
Generator
43,000 m2
Rotary Stoker
(7 stages)
600 t/day
(200 t/day X 3 units)
800~900°C
(Outlet Gas)
1,1 00-2, 500 kcal/kg
Below 3%
(800°C, 3 hours)
3 Units
4,000 kW X 2 units
3.   BASIC  RESEARCH AND EXPERIMENT  ON COINCINERATION
3.1  CONDITIONS  OF  COINCINERATION EXPERIMENT
     The type of a refuse incinerator was already decided as shown in Table 1 and
Fig.  4 before the start of this research. Then, the following experimental conditions
were given.
                         I—y Flow of Gas
                                                                     Exhiitt Gu
                                                                     Trotment FuUhwi
                                                       10  Elcctnc Diwl Collector
12 ExhtuitGM
  Tintnwnt FuUltlM
  (Tow«r for Abioiption
  and CondtBuUon)
13 Suck
14 Control Room
                    Fig. 4    Schematic of Incineration Plant
                                      71

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    a.  The incinerator burns exclusively municipal refuse. No consideration is taken
for the incineration of sewage sludge.
    b.  With the incineration of sludge, no adverse effects are given to the incine-
rator. (On combustibility, composition  of exhaust gas, amount of unburned sub-
stances and like that.)
    c.  To reduce the quantity of ash and bad effects on the exhaust gas treatment
facilities, lime and ferric salt are not used as sludge conditioner.
    d.  The digestion process is  not  adopted because it reduces the heat value of
sludge.
    e.  Sludge is completely burned within one hour in the incinerator, particularly
with care to prevent sludge from falling through the slit  between rotary  stokers
(about 8 mm wide).
    f.  For overhaul of the incinerator,  the operation is shut down for a week once
a year.
    g.   Sludge is dried to the  extent of similar low heat value to refuse (1,100~
2,500 Kcal/kg sludge).
     If the heat value of organic matter is assumed to be 5,000 Kcal/kg, the low heat
value of sludge is expressed in the following equation:
                                          X 600
          where,  Ha : Low heat value of sludge (Kcal/kg)
                 a   : Organic content in sludge (%)
                 w  : Moisture content in  sludge (%)
     The relation between  the low heat value computed by the above equation and
the moisture content is shown in Fig. 5. The Figure shows clearly that the low heat
value of sludge is in inverse proportion to its moisture content, and that the mois-
ture content should  be reduced by 60~25% to make sludge's low heat value similar
to municipal refuse in case that organic content of sludge is 70%.
                   Fig. 5
                                      40      60
                                       Moisture Content (%)
Relation Between Low Heat  Value
and Moisture  Content of Sludge
                                      72

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     The low heat value of about  1,200 Kcul/kg is necessary for the stable incinera-
tion of municipal refuse. So the moisture content of sludge is set below 50% in this
research.
3.2  ALTERNATIVES OF  SLUDGE  TREATMENT
     Considering the  conditions mentioned in  Section 3.1, two processes (A) and
(B) have been thought out as shown in Figs. 6 and 7 respectively, where the combi-
nation of unit processes possible for practical use at present is designed.
Thickened
Sludge
                                                                -»«• Deodorization

Polymer
Condi 	
tioning
Vastewater
'acilitic-
1 >
\ r '




Ultra i-
                      Fig. 6 Polymer Conditioning Process (A)
Thickened
Sludge
                 Steam
                           Odor
	 r^ r~
i '
t !
Heat
Treatment
VVastewater
1 acilities
	 T~
1
1



Filtrate

ncl * Pdleti- *u
^•j * zation *^

                                                                       Transport
                            Fig. 7 Heat Treatment Process (B)

     Under the condition that inorganic coagulants such  as lime and ferric salts are
not used, two dewatering processes seem practical: one  is the dewatering of poly-
mer-conditioned sludge and the other is that of heat-treated sludge without dosage.
In the former process, the centrifuge, belt press filter or screw press are available.
As the centrifuge is said to produce sludge cake of higher moisture content than two
other machines, more amount of thermal energy is required in the subsequent drying
process to gain the designed moisture content. That's why it has been excluded from
this plan.
     In the latter process, the moisture content of well heat-treated sludge cake will
be less than 50% by the  filter press without dosage of conditioner. Accordingly, the
drying process by steam seems unnecessary.
    There are three types of the drying system, indirect steam heating with paddle,
steam  pipe heating  and  direct air current heating. In this  plan, the paddle type
heating is adopted because the heat  source is steam and  the second  type has a
problem  that sewage sludge  containing  much organic substance adheres  to heat
transmitting surface.
                                      73

-------
     Although their effectiveness to sewage sludge is not  confirmed, there are two
types of pelletizing machines. One is by briquetting, the other is by pushing out
with screw or piston. Pelletized cake is required strength not to break due to vibra-
tion and moisture not to adhere to each other on the way to the incinerator.
3.3  EVALUATION OF EACH  UNIT  PROCESS BY EXPERIMENT
3.3.1      DEWATERING
     Belt press filter and screw press have been evaluated  for the sludge conditioned
with polymer and filter press for the heat-treated sludge.
    a.    Belt Press Filter
     The structure of the belt press filter used in the test is shown in Fig. 8 and its
belt is 50 cm wide. The typical result is indicated in Table 2. As belt press filter has
been put  into practical use, the result of this test is estimated to be reliable. Con-
sequently, dewatered cake of moisture  content of 70 to 75% will be produced at
filter  yield of 100 to 200 kg DS/m-hr with polymer dosage of 0.7 to 1.0% for the
sludge of solids  content 3.5% although  the result deplends on the kinds of sludge.
                    0.      0
       1   Upper Frame
       2   Lower Frame
       3   Upper Washwater Unit
       4   Lower Washwater Unit
       5   Scraper
       6   Belt Driving Motor and Speed Reducer
 7   Upper Belt
 8   Lower Belt
 9   Filtrate Drain
10   Belt Drive Unit
11   Belt Tensioning Roller
12   Belt Driving Roller
                                 Fig. 8 Belt Press Filter
                                       74

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                   Table 2 Dewatering Characteristics of Belt Press Filter
Experiment
Number



1
2
3
Polymer
Dosage


(%/DS)
r 0.4
^~ 0.7
1.0
Solids
Content in
Sludge

(%)
3.3
3.3
3.3
Sludge
Feed
Rate

(rn3/hr)
2.6 "
2.8
2.8 ~1
Belt
Tension


(kg/cm2)
3.0
3.0
3.0 ~l
Moisture
Content in
Dewatered
Cake
(%)
68.1
71.1
70.7
Filter
Yield


(kgDS/nrhr)
137
192
192
Solids
Recovery


(%)
98.6
99.3
99.1
 (Note) Sludge used was mixed sludge of the Toba plant.
       Polymer used was KAYAFLOC C-599-1H.

     b.   Screw Press
     There have  been still few cases of full-scale press used for dewatering sewage
sludge. Polymer-conditioned sludge is put into the  cylindrical screen made of the
punched steel,  slowly  pressurized and dewatered by  screw. The screw press used in
the test is shown in Fig. 9. This is a pilot machine with the inside diameter of 200
mm and  the length of 2,000 mm. It is able to feed steam into  screw shaft and
heat sludge at 40~70°C for the improvement of dewatering efficiency.
 Drain
1
2
3
4
            Cake
Hopper
Screen
Screw Shaft
Screw Blade
                                                Filtrate
5    Tapered Cone
6    Dewatered Cake Discharge
7    Filtrate Outlet
                               Fig. 9 Screw Press
                                      75

-------
     The typical test result is indicated in Table 3. The result shows that the proper-
ties of dewatered  cake was  stable  on any condition of heating or not  and change
of rotating  speed. But with  heating, the moisture content of dewatered cake was
reduced  by 6~10% and  the sludge  feed rate increased  by 10~20% as compared
with the operation without heating. When the screw press is scaled up, the moisture
content  of  dewatered cake tends to increase. So the reasearch is required in  the
practical scale.
                    Table 3 Dewatering Characteristics of Screw Press
Experiment
Number
1
2
3
4
5
6
7
8
Polymer
Dosage
(%/DS)
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
Solids
Content
in Sludge
(%)
3.9
3.9
3.9
3.9 |
3.9 i
3.9
3.9
3.9
Sludge
Feed
Rate
(kgDS/hr)
2.8
5.7
10.3
12.3
2.1
5.1
9.2
11.0
Rotation
Speed
(r.pjn.)
0.08
0.16
0.32
0.48
0.08
0.16
0.32
0.48
Heating
Yes
Yes
Yes
Yes
No
No
No
No
Steam
Pressure
(kg/cm2G)
1
1
1
1
0
0
0
0
SSof
Filtrate
(ppm)
1,400
590
810
1,400
815
1,010
1,500
1,400
Solids
Recovery
(%)
95.5
98.3
97.6
95.5
96.7
H98.1
95.5
95.2
Moisture
Content
in Caki
(%)
56.3
58.1
65.5
69.4
65.4
68.1
72.3
78.0
  (Note)  Sludge used was mixed sludge of the Toba Plant.
        Polymer used was DIAFLOC KP-201A.

     c.    Filter Press
     In  the heat treatment process studied in this test, the low temperature system
(145°C~175°C) is adopted. As compared with the high temperature system (200°C),
it is effective for the characteristics of filtrate and deordorization. The pilot machine
with the filteration  area of 0.07  m2 was used to evaluate its performance of de-
watering heat-treated sludge and to get the condition required for the effective cake
moisture  content. To evaluate  the subsequent  process, the dewatered cake was
produced by the  test machine with the filtration area of 4.0 m2. The result of the
dewatering test for  the  two machines  is shown in Table 4.  There are many full-
scale filter presses operated for  heat-treated sludge, so it may be possible to get de-
watered cake of moisture content 35~50% at filter yield of 5~10 kg/m2-hr.
                    Table 4  Dewatering Characteristics of Filter Press
\ Item
FiTtX
ratiorX
Area \
0.07 m2
4.0 m1
Solids
Content
in
Sludge
(%)

6.3
8.1
9.6
9.4
Operational Conditions
Injecting
Time
(min.)
A
5
B
10
C
15
5
Pressure
(kg/cm2 )
4
5
Squeezing
Time
(min.)
10
13
Pressure
(kg/cm2 )
13
13
Results
Cake
Removal
A
Good
Good
Good
6
Good
Good
Good
C
Good
Good
Good
Good
Moisture Con-
tent in De-
watered Cake
A
38.6
38.7
40.4
B
30.1
43.8
42.6
C
40.3
45.0
48.3
48.7
Filter
Yield
,(kgDS/m2hr)
A
6.43
5.98
7.10
B
5.47
5.24
6.42
C
5.03
5.89
5.86
5.82
(Note) The sludge used was mixed sludge of the Toba Plant.
                                        76

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3.3.2  DYR1NG
     The moisture content of polymer-conditioned sludge cake is about 65~75%.
Sucli a cake has not enough to low heat value and has adverse effects on combusti-
bility because  it is  soft enough to aggregate in the  transport and refuse  pit. To
settle the problem, a test was conducted with the paddle-type indirect steam drier
for drying the dewatered  cake with steam produced from the waste heat boiler
of the refuse incinerator. The test was conducted using sludge cake produced from
the screw press at the Toba plant. The paddle-type indirect steam drier is shown
in Fig.  10. The characteristics of dewatered cake used for the test are shown in
Table 5 and the test result is shown in Table 6.
     It has been confirmed that the continuous drying of polymer conditioned
sludge  was conducted well by  the  paddle-type  indirect  steam drier without  the
sludge  adhering to the heat-transmitting surface. The particle size distribution of
dried cake is  changed with the change of the moisture content of dried  cake as
shown  in Fig. 11.  The appropriate pelletization is required because the result indi-
cates that the  dried cake produced by the test drier is expected to fall from between
grates of incinerator.
   Table 5 Characteristics of Dewatered Cake       Table 6 Drying Test of Dewatered Cake
Moisture
Content
(%)
63.6
Ignition
Loss
(%)
62.9
Heat
Value
(kcal/kgDS)
3,660
C
(%)
37.9
H
(%)
5.7
N
(%>
3.7


Steam Pressure (kg/cm2 )
Steam Temperature (°C)
Moisture Contnet in Dewatered
Cake (kg/hr)
Dewatered Cake Feed Rate (kg/hr)
Moisture Content in Dried Cake (%)
Dried Cake Discharge Rate (kg/hr)
Cake Temperature in Drier (°C)
2.5
138
63.6
140
33.2
76.3
95
                     Dewatered Cake
                                           Paddle
                                                             —•-  Exhaust Gas
                                                            C
              Fig. 10   Paddle-Type  Indirect Steam  Drier
                                      77

-------
             100
              90
             80
_   70
g
S   60
(O
cc
S1
1
«V
§
u   40
                                               Dried Cake
                                               Moisture Content 41.5%
             50 I-
          H  30
             20
             10
                                               Dried Cake
                                               Moisture Content 33.2%
                                        10
                                                                 20
                                   Mesh Size of Sieves (mm)

                Fig. 11   Particle Size Distribution of  Dried  Cake

3.3.3  PELLETIZATION
     The moisture content of dewatered cake by the belt press filter or screw press
with polymer conditioning is higher  and should be  reduced to proper moisture
content by  drying. Although  it depends on the moisture content, dried cake is
not  uniform  in the  particle  size and  may  cause the  pulverulent  condition.
Dewatered cake by filter press after the  heat treatment has the moisture content
required  without the drying  process.  But, as dewatered cake is in the shape of
large plate,  it should be pulverized mechanically. The particle size of the pulver-
ized cake is  not uniform and too large that the bad effects are given to the combusti-
bility and too small  that the fall from  between grates of incinerator is caused.
     In this  plan, the test was conducted for the screw-type pelletization  machine
under the condition that dewatered cake should be pelletized to the proper size
even if any  type of the dewatering machine is used. The pelletized cake should be
so strong  in resisting the shock and consolidation in process and be well combusti-
ble. Accordingly, the test was also conducted for the strength of pelletized cake.
     a.    Test of Polymer-Conditioned Sludge Cake
     Dewatered  cake  by screw press was dried  to the moisture content of 23.6%,
33.3%, 41.5% respectively for the  pelletization test using the screw-type pelletiz-
ing machine as shown in Fig.  12. The excellent  cylindrical pelletized  cake of 010,
12, 14 mm is obtained as shown in Fig. 13.
     b.    Test of Heat-Treated Sludge Cake
     It is unable to  pelletize  the heat-treated sludge  cake  if the moisture content
                                          78

-------
Dewatered Cake
T Hopper
Reduction 	
	 	 pear \ /
w,,.... , , r"1 t *"
.. h /\ A
Motor .-;." I I ' :
] IV V V


Trans-
port
Zone

' Bavel f-,
^ A /\ A M °

V Y V V N a


-*. Incinerator
-»
Screw X /f^A
X I/* ° o A
Compress-
ing ,
Zone /I
:*°
\\° °y
vcs/
                                         Uniform
                                         pressure zone
010~14mm
                     Fig. 12 Screw-Type Pushing Pelletizer
                              012mm
                              Moisture Content 33.2%
                              5cm-
                          Fig. 13 Pelletized Cake

becomes less than 30%, and the pelletized cakes are adhered each other to produce
a large  cake if the moisture content becomes more  than  50%. At the moisture
content of 30~50^,  the  excellent  pelletized  cake  with the diameter of 12 mm
and the length of 30~50  mm is obtained.
    To test the strength of pelletized cake, 500 grams of cake in the above (a) and
(b) cases are put in an 18 liter can and then dropped 3 meters down on the concrete
floor 12 times. As a result of the test, the strength has been adjusted as good because
the rate of passing through  10 mm sieve was less than 5% for both cases.
3.3.4   COMBUSTIBILITY
    To  investigate the combustibility  of pelletized  cake, the incineration test
was conducted in  the electric  furnace (200V, 7.5kW, W200XH150XL300). The
typical  test result for polymer-conditioned sludge  cake and  heat-treated sludge
cake is shown in Fig. 14.
                                      79

-------
                          Table 7  Incineration of Dried Cake
"\^
Polymer
Conditioned
Sludge Cake
Heat-Treated
Sludge Cake
Ignition Lo«
Beloie Incineration
<<„') j
67.3
52.7
Size of Pelk'ii
/.at ion
(mm)
Moisture
Content
(%)
01 : Cylindrical 1 23.6
\ I Cylindrical I 33.2
012 Cylindrical | 41 5
Ol, 'CyhiidiK.il
52.7
Ignition Loss of Ash after
Incineration at 800°C
10 min. Burning
6.3
8.3
13.2
9.9
60 min. Burning
0.05
0.09
0.11
0.37
                                    Burning Temperature 800 C
                                    Polymer-Conditioned Sludge Cake
                                  20      30      40
                                  Time of Incineration (Minute)
                                                               60
               Fig.  14  Decreasing  Curve of  Combustibles  Content

     In the incineration test with the electric furnace, considerable non-combusti-
bles remained  in ash at the temperature of 800°C and the incineration period of
10  minutes.  In case of the one-hour incineration period, it was almost completely
reduced  to ash and the non-combustible rate was less than 1%. Fig. 14 shows that
the incineration speed  of pelletized cake is slower than that of cake before pelleti-
zation, but it  was  almost the same speed 40 minutes later. Although  the incinera-
tion with the electric furnace differs from the incineration with the full-scale incine-
rator, it is expected to be possible to incinerate  pelletized cake with  refuse unless
the ratio of pelletized cake to refuse is    so high.
                                        80

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 3.3.5   CONCLUSION  ON  LABORATORY TEST
     The laboratory test was conducted for unit process of two treatment processes
 —(A)  polymer  conditioning and (B) heat  treatment—under  the  condition  to
 incinerate sewage sludge and municipal refuse at the full-scale  plant. The  result
 was obtained that both processes u>uld produce the pelletized cake for coincinera-
 tion. It also showed that there is no particular problem on its combustibility.

 4.   COINCINERTION  TEST BY FULL-SCALE PLANT
 4.1  OBJECT
     This test was conducted to investigate the incineration of the pelletized cake
 by  full-scale refuse incinerator based on  the result  obtained by the laboratory
 test described  in  the  previous section.  The investigation  was carried out for the
 following problems that may  be caused by the difference of physical  and chemical
 characteristics between sewage sludge and municipal refuse.
     a.   Effect on NOx concenl'.ation  in  exhaust  gas and effect of dust load  on
 electric dust collector.
     b.   Hffect on the  incineration .st.nc in an incineiaior ;md the ignition loss of
 ash.
 4.2  METHOD
     The incinerator used for the test is  a rotary  stoker-type refuse incinerator
 (the same type as that  at the Higashi Re I use Incineration Plant) in M city. The
 capacity is ISO ton/clay and it passed four years after  the operation of incinerator.
 As the exhaust gas treatment facilities, the electric dust collector (dry  type) and the
 alkali washing facilities are installed. Fig  15 shows the schematic  of the incinerator
 and the monitoring points and the sampling points for investigation.
     At  the incineration plant, the collected refuse  is stored in the refuse pit and
 then weighed by the refuse supply crane. After the refuse is fed into the incinerator
 from the feed hopper, it is dried  and incinerated in moving from the upper side
 to the lower side  on the rotary grates. Both the incinerated ash and the riddlings
 from the rotary grates are put in the ash cooling tank and then are transported
 by  truck from the  ash  bunker. The  exhaust  gas passes through the duct and is
 washed by  water  jet at the gas cooling  chambei.  After smoke dust is collected
by the  electric  dust collector, toxic gases such as HC1 are removed with the  alkali
purification and then the gas is discharged from stack.
     The monitoring and sampling were conducted at each point  shown in Fig.  15
in order to confirm on  whether any effect  is caused on by-products  (exhaust gas,
 ash,  riddlings, wastewater, etc.) of the coincineration with sludge in the incineration
process abovementioned.
     Two kinds of sludge were used for the test—(A) pelletized  cake of polymer-
conditioned sludge and (B)  pelletized  cake  of heat-treated  sludge. Pelletized cake
was fed into the hopper  with man  power from a 20  kg bag  so that the ratio of the
weight of fed pelletized  cake to that of the refuse  fed by crane might be fixed.
The  coincineration test was carried out for  three days October 24-26, 1978. The
ratio of fed sludge quantity to refuse and the feeding pattern in the test are shown
 in Table 8.
                                     81

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                            I  Gas Analysis
                            :  Gib \n,.|v,is
                            i  I'onUni .iusMeabliH"ii("ii
                              of NO. Oi.CO, ji..l CO
                            •I  Sampln z ol ImsK
                              CaptuuJ by II-
                            s  Sampling ol Coohng
                              ftasic* ilei
d  Sampling of Suubbeil
  Wastewater
7  Sampling ot A>hes
8  Sampling of Riddlmgs
y  S.implmg ol Keguse auii
  Sludge
           Fig. 15   Schematic of Incineration Plant and Sampling Points

     Test was conducted at the average sludge mixing rate of  10% (which is esti-
mated from  the  construction  plan  of incinerator shown in Table I) and 20%. On
the fourth day of  the test (October 27), the sludge was not fed, and the test was
conducted for the incineration of only refuse.
                        Table 8 Ratio of Sludge Cake to Refuse
Item
Polymer
Sludge Cake

Heat-Treated
Sludge Cake



Ort 24


CM 25
Opt 7f\

Date
10:00-12:00
13:00-15:00
10.00-12:00
13:00-15:00
10.00-12:00
13:00-15:00
Ratio of
Sludge Cake
(%)
9.8 ( 8.9)
19.1 (16.0)
9.9 ( 9.0)
18.8(15.8)
19.1 (16.1)
17.7 (15.1)
                     (Note)  Figures in parentheses show the ratio of
                           sludge cake to total.

4.3  ANALYSIS  OF REFUSE  AND SLUDGE
     The composition of refuse of M  city in the test is shown in Table  9. The
analysis  was conducted for about 3~4  kg of refuse  taken out by crane from the
refuse pit  once a day. The composition of refuse of Kyoto City is also shown for
comparison. The  composition of refuse in M  city is featured by the high  rate of
paper  and the small rate of kitchen wastes.  During the test  period, the low heat
value of refuse was 2,160~2,530 Kcal/kg.
                                       82

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     Table 10 shows the characteristics of sludge used for the test. Although there
was no large difference of the characteristics between two kinds of sludge prepared
for the test,  the ignition loss was much lower than that of normal sludge, and the
low heat  value is estimated at about  1,000 Kcal/kg. The fact that the moisture
contnet of pelletized cake was lower than the objective value is ascribed  to the
natural drying because the pelletized cake in paper bag was stored inside the build-
ing for 7 to 10 days until the incineration test was conducted.

                  Table 9 Composition of Refuse (On Dry Basis) (%)
^^
MCity
Kyoto City
Paper
56.0
32.6
Plastics
13.0
10.0
Garbage
12.5
34.7
Other
Combustibles
10.2
12.6
Metal
4.6
3.6
Non-;
Combustibles
3.7
6.5
Total
100
100

4-Day Average
Data in 1975
Moisture
Content (%)
39.0
45.5
                  Table 10 Characteristics of Dried Cake
^^-— ^__
Sludge Treatment Process
Shape
Moisture Content
Apparent Specific Gravity
Ignition Loss
Elemental Composition

H
C
N
Polymer Conditioned Sludge Cake
Polymer Conditioning -»
De watering -» Drying -»
Pelletization
Cylindrical
Diameter 1 2 mm
Length 20 mm
14.6%
0.69
36.6%
2.6%
14.8%
' 3.2%
Heat-Treated Sludge Cake
Heat Treatment -» Dewatering
Pallatization
Cylindrical
Diameter 12 mm
Length 20 mm
30.5%
0.63
39.4%
3.0%
20.3%
2.6%
4.4  RESULT
4.4.1  MEASUREMENT OF EXHAUST GAS
     Concentrations of nitrogen oxide (NOx), oxygen (Oj), carbon dioxide (CO2)
and carbon monoxide (CO) of exhaust gas are shown in Table 11.
     The Table shows that there were no big differences in concentrations of four
substances of exhaust gas at the incineration and non-incineration of sludge and no
effect was  found by the incineration of sludge. There  was also almost no effect
of the sludge incineration on quantity of dust, composition of elements (C, H, N)
in unburned materials, exhaust gas flow rate and characteristics of wastewater from
iCxhaust gas washing.

4.4.2  ANALYSIS OF  ASH AND RIDDLINGS
     As described in Section 4,2, the  fallen  ash and riddlings from grates are mixed
in the cooling water basin to produce ash. The ash was then sampled on the ash
conveyor and was analyzed. The riddh'ngs was sampled just before reaching the
ash cooling basin from the conveyor for riddlings.
                                    83

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                          Table 11  Analysis of Exhaust Gas
                                   from Incinerator
~~~^~---_^^ Item
Date ~-— - __
Incineration
with
Sludge Cake
Incineration
Without
Sludge Cake
Oct. 24
25
26
Average
Oct. 24
25
26
27
Average
NOx
(ppm)
107
104
104
105
104
92
106
105
102
03
(%)
14.9
14.6
14.3
14.6
15.3
14.9
14.4
14.4
14.7
CO2
(%)
5.9
6.3
6.0
6.1
6.1
5.6
5.7
6.6
6.1
CO
(ppm)
193
215
215
208
174
250
221
171
201
     Ash is classified in substances of incinerate residual ash content, metals, glass
ware, non-combustibles and sludge (all those adjusted as sludge). The rate of sludge
in the ash increases with time after it passes about one hour from the start of sludge
feeding. And  the  quantity of riddlings also increases, and  the rate of sludge in
riddlings became more than 50% in some cases.
     As shown in Table 12, the ignition loss of incinerate residual  ash is found to
be slightly higher in  the incineration with  sludge than that  in the incineration of
only refuse.
     In the incineration with sludge, the non-combustibles of incinerate residual ash
content in ash increases. It indicates that the incineration state in the incinerator is
expected to have  been worsened to some extent due to the feed of sludge. But it
seems to have been caused by the fact that non-combustible sludge  in riddlings was
considerably  remained  in ash. For both the temperature and incinerating state in
the incinerator, there was no large  difference between the incineration and non-
incineration of sludge.
     There was much sludge in riddlings.  It was caused by  the factors—it passed
four years after the operation of incinerator used for the test; the gap of grates
became  larger than that assumed at the outset due  to wear and damage; and  the
difference of the  physical characteristics  between  pelletized cake and  municipal
refuse. As  the particle size  of pelletized  cake  is small and  its apparent specific
gravity is large, sludge is stirred  and  concentrated on the lower part of refuse layer
(on grates) while  it  moves on grates. A huge quantity of the cake is believed to
fall from the slit  of grates. There is another factor that the refuse layer thickness
is about 0.3 m, very thinner  than the normal layer thickness of about 1.0 m at the
entrance of incinerator.
     Judging from these factors, it is necessary to set the sludge mixing rate properly
and to feed the sludge uniformly to the incinerator for the coincineration of refuse
and sludge.  The completely-incinerated  sludge in ash remains unchanged in shape
of the pelletized cake and  this shows that  the pelletized cake will not be destroyed
in the incinerator.
                                        84

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                     Table 12  Ignition Losses of Residual Ash
                             and Sludge in Ash
Item
\
Date ^^
Oct. 24
Oct. 25
Oct. 26
Oct. 27
9:30
10:30
11:30
14:30
15:30
9:30
10:30
11:30
14:30
15:30
9:30
10:30
11:30
14:30
15:30
9:30
10:30
11:30
14:30
15:30
Average in
Incineration
Without
Sludge Cake
Average in
Incineration
With
Sludge Cake
Average
Ignition Loss
of Residual Ash
(%)
7.5
7.1
5.6
9.1
7.6
5.3
10.2
7.9
10.1
11.4
7.2
5.9
6.7
9.7
12.3
8.7
Not Measured
9.4
9.8
8.6
8.0
8.9
8.4
Ignition Loss
of Sludge
(%)
-
-
10.9
12.3
7.6
-
-
12.5
18.4
22.2
-
-
18.5
17.3
29.5
-
-
-
-
-


16.6
4.5  CONCLUSION  OF  FULL-SCALE  PLANT TEST
     The  following items have been made clear for the coincineration  of sewage
sludge and municipal refuse in the test.
    a.  It  may be possible to incinerate sewage sludge with municipal refuse in the
rotary stoker type incinerator if pretreatment of sludge is conducted properly.
    b.  No effect of coincineration was found on exhaust gas.
    c.  No big change was also found on smoke dust, exhaust gas flow, character-
istics of exhaust gas and wastewater.
    d.  To prevent  the fall of sludge from grates, it is necessary  to pelletize the
dewatered cake as big as possible under the condition that the combustibility may
not be worsened.
    e.  In the case that sludge  and refuse are stored and mixed in a pit in the incine-
rator, it is necessary to mix them as uniformly as possible for feeding into hopper.
                                     85

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4.6  ADDITIONAL TEST (ENLARGEMENT OF PELLETIZED CAKE)
     As described  in  the  previous section, the pelletized  cake is expected to fall
from  grates it" the  size of  pelletized cake is around 12 mm on incineration by full-
scale  incinerator. Then, it was attemted to produce (he  pelletized cake of larger
particle size. The  characteristics  was examined in the laboratory  test as in the
similar test conducted in Section 3. The result is briefly described.
     Sludge to be pelletized is the  combined sludge  from domestic wastewater,
and its organic content is about 80%. The pelletized cake was produced by both (A)
and (B) processes described in Section 3.2.2. Its moisture content is 33~40% and its
shape is about 020 mm X 30 mm long, 030mm X 30 mm long. It was possible to
produce the excellent cake.  Results of the test for the strength and incineration
by the electric furnace was also satisfactory.
     In  the coincineration test  by the electric furnace, various shape of pelletized
cake  was  produced and tested  to investigate the effects of the shape  and size of
pelletized  cake on combustibility. It  was found that  the  pelletized  cake of larger
surface area and smaller initial weight is more combustible if it is the same volume.
It means that the cake of thin flat  board shape and light weight is more combustible.
The  020~30 mm  cylindrical cake produced for the test  won't cause any adverse
effect on  the combustibility especially in the incinerato:. Rather, it is better to
reduce the quantity  of riddlings  by  making  larger pelletized cake than 012  mm
cylindrical cake produced for the full-scale plant test.

5.   PROBLEMS  IN  FUTURE
     The test for coincineration of sewage sludge in the municpal refuse incinerator
was carried out to investigate mainly the effective utilization of energy and the pre-
treatment technology of sludge for coincinoration. As a  result of investigation, it
was found that the incineration of sludge with municipal refuse is possible for cake
produced  in the treatment processes—(A)  polymer conditioning process and (B)
heat treatment process.
     But for the enforcement of this plan, there still  remains the problems to be
studied. These problems are described below:
   a.  For both the  (A)  and (B) processes, the huge quantity of thermal energy
is required to produce the objective pelletized cake.  It is covered by  the surplus
heat produced in the  refuse  incinerator but  the quantity is limitted. Consequently,
the maximum efficiency and the smaller amount of heat consumption are regarded
better for the  heat to be used in the sludge treatment. For this purpose, the solids
content of thickened sludge should be  increased in both processes. And, for (A)
process, it  is necessary to  reduce the load for the drier by producing lower moisture
content of sludge  cake with increasing dewatering efficiency. For (B) process, it is
necessary  to make the volume of heat treatment reactor smaller and to  reduce the
heat consumption for heat treatment.
   b. It  is necessary to do comparative evaluation of the construction cost and the
operation  and maintenance costs of the total system after learning about the neces-
sary energy and other factors for both processes.
   c.  The evaluation on sludge  treatment process by tests was carried out for
                                     86

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each unit process. At the full-scale plant, these processes are organically combined
for operation. Accordingly, it  is necessary  to study  the operational efficiency of
the whole sludge treatment process which was not confirmed in the laboratory test,
and the countermeasures during the  period of shut-down caused by the overhaul
of incinerator.

6.   CONCLUSION
     The role of the wastewater treatment plant and the refuse incineration plant
as the municipal environment  facilities will become more important in the future.
The  construction  of effective  and economic facilities,  and the maintenance  and
operation are necessitated in consideration of the  effective use of surplus energy
because the huge  quantity of energy is consumed  at these facilities. In this situa-
tion,  the  coincineration of sewage sludge  and municipal refuse  is regarded as a
subject to be studied for the construction  of these  facilities.  The construction of
full-scale plant is expected to be started as early as possible after the further investi-
gation is made for the enforcement of the plan.
                                      87

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                                     Eighth US/Japan Conference

                                                on

                                     Sewage Treatment Technology
NEW ASPECTS OF SLUDGE INCINERATION

                IN YOKOHAMA
                 October 12. 1981

                 Cmcmati, Ohio
The work  described in this paper was not funded by the
U.S. Environmental Protection Agency.  The contents do
not necessarily reflect the views of the Agency and no
official  endorsement should be inferred.
              Shigeki Miyakoshi

              Senior Technical Advisor

              Sewage Works Bureau

              City of Yokohama
                        89

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Foreward
     With the spreading of sewerage system, the amount of sludge produced in sewage
treatment plants has increased and serious problems have been brought about regard-
ing its treatment and disposal.
     In Yokohama city, part of the sludge has been returned to green zones and farm
lands as  "dried sludge fertilizer"  since 1977 and the bulk has been  disposed of in
garbage dumping plots.
     However, with the advance of urbanization  everywhere  in the city, which has
been taking place with the high economic growth since the beginning of the 1960s, it
has become more and more difficult for the city authority to secure  a new  plot for
sludge disposal.
     Although it has been the basic policy for sludge to be disposed of by being
returned   to  the recycling  system  of natural  materials so that  the  ecological
environment  can be improved rather than harmed, it was  decided as a tentative
measure to incinerate all the sludge in order to extend the useful life of existing dis-
posal grounds which are precious  in the circumstances described  above and to
improve the quality of sludge.
     Eleven treatment plants in all are involved in the sewerage works plan of the  city
(eight plants  are in operation as of the end of fiscal 1980). The sludge from these
treatment plant is to be processed by two base treating plants, viz. Kanazawa sewage
treatment plant  and the Hokubu second sewage treatment plant located in coastal
areas. Sewage treatment plants are planned to be  connected to the base plants with
pipe lines which transport sludge under pressure. Until the pipe line is made complete,
sludge cake must be carried by trucks for incineration at the base plants.
     On  the basis of the plan described above, a maltiple-hearth furnace incinerator
was constructed  at Kanazawa sewage treatment plant and put into operation in 1978.
     Aiming at energy conservation, a fluidiged bed furnace, which utilizes pulverized
coal  as  the supplementary  fuel instead of  oil, was completed in Hokubu second
sewage treatment plant in March 1981.
     In  order to further conserve energy, experiments have been carried out on a
pilot plant with the object of establishing a combination system of "drying"  and
"incineration".
     Detailed descriptions of the treatment  facilities are given in the following para-
graphs.

1.   Sludge Incineration by .Maltiple-hearth Furnace Located Apart from Sewage
     Treatment Plant Site
1.1  Outline of facility
     Since it  was the first experience for the city to construct a sludge incinerator,
the sewarage  works bureau  formed  a committee  consisting of the bureaus  officials
which made preliminary investigations for two years starting with a survey of incine-
ration performance in other cities. On the basis of the general plan and of the estimat-
ed amount of sludge cake  that would  be  produced in  a year when it is put into
operation, the capacity of the facility was set at  100 ton per day. Whereas there was
only one fluidized bed furnace in operation with a capacity of less than 40 ton a day
                                      90

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at  that  time, several  multi-
ple-hearth   furnace  with  a
capacity of 150 ton per day
were already  in  practical use
and it was decided to adopt a
multiple-hearth furnace.
      Design specifications of
the sludge  incinerator  were
set forth as follows:
 a.   Multiple-hearth furnace
      Incinerating capacity:
      100 ton per day, capa-
      ble of operating for 30
      minutes  at  the   maxi-
      mum  capacity (120 per-
      cent  of  the rated capa-
      city)
      Properties  of the  sludge
      to be incinerated:
      Kind:
                                                 illlllllllHilliJEDJC
                                                                   ID
b.
                                    21 Chemical settling tanks
                                    22 Rapid sand filters
                                    23 Activated carbon filters
                                    24 Sterilizers
Storm water storage tank
Preaeratton tanks
Administration building
Primary sedimentation tanks
Aeration tank
Final settling lanks
Sludge thickening tanks
Sand filtration
Chi on nation tanks
Tertiary treatment water conveyance
Sludge storage tanks
Sludge thickening tanks
Administration building
Wet air oxidation facilities
Sludge digesting tanks
Sludge elutnation tanks
Scrubber wastewater treatment plant
Sludge inctneartor (Maltiple-hearth furnace)
Sludge incinerator (Rutdized bed furnace)
Sludge de water ing facilities
c.
                                  Fig. 1-1    General plan of Kanazawa sewage treatment plant
                               De watered cakes of raw sludge and anaerobic digested
                               sludge.
    Method of dewatering:  Vacuum  or  pressure  filtration  using  inorganic  coagu-
                               lant, and centrifuge using organic coagulant
    Water content:           65 to 80 percent
    Calorific value:           1400 to 3000 kcal/kg-DS
    Ash content:             About 40 percent
    Combustibles:           About 60 percent
  1  Cooling tower                 12  Thickener
  2 Scrubber wastewater receiving tank  13  Sludge supply tank
  3 Reaction tank                 14  Pressure filter
  4 pH controlling tank             15  Storage hopper for sludge cake
  5 Polymar mixing tank
  6 Settling tank
  7 etiolating tank
  8 Distribution tank
  9 Sand filter
 10 Neutralizing tank
 11  Sludge oxidizing tank
                                                               16  Truck weigh-bridge
                                                               17  Sludge storage pit
                                                               18  Bucket crane
                                                               19  Constant rate feeder
                                                               20  Conveyor weigh ing unit
                                                               21  100t/day multiple-hearth furnace
                                                               22  Ash hopper
                                                               23  Scrubber
                                                               24  Electrostatic precipitator
                                                               25  After burner
                                                               26  Stack
                      Fig. 1-2    Layout of sludge incineration facility
                                                     91

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Fig. 1-3
Flow diagram of sludge
incineration facility
                                      1  Truck weigh bridge
                                      2  Sludge storage
                                      3  Bucket crane
                                      4  Constant rate feeder
                                      5  Conveyor weighing unit
                                      6  Multiple-hearth furnace
 7 Ash hopper
 8 Scrubber
 9 Electro-static
10 After burner
11 Stack
                                                                              precipitator
                         Table 1 -1   Summary of sludge incineration facility
Name
Building
Truck weighbridge
Crane
Constant rate
feeder
Incinerator
Auxiliary
burner
Ash hopper
Scrubber
Electrostatic
precipitator
Afterburner
Stack
Description
Total floor space 1437m2 Steel-frame with ALC plates
partially rainforced concrete structure
Weighing method Static weighing
Weighing capacity 30 ton (load cell type) minimum 20 kg
Overhead travelling with grab bucket
Rated load 1 ton (by grab bucket)
Span 8.4m
Range of lift 20.2m
Length of travel 25m
Bucket Double wired clamshell type
Steel, square, screw feeder, downward conveying type
Capacity 25m 3
Rate of conveyance 0.55 - 6.6 ton/hr
Screw Twin type ribbon screw x 3
Maltiple-hearth furnace
Capacity 100 ton/day
Number of hearths 8
Diameter 5710mm
Heating method Indirect heating
Hot ail generation by gas burning type
Hot air temperature 900- 1 1 00°C
Combustion capacity LNG 1 ,500,000 kcal/hr x 2
Steel, truncated cone shape
Capacity 35m3
Ash humidifier Batch type (paddle mixer)
Kneading capacity Max. 1m3
1 set
2 sets
1 set
1 set
2 sets
2 sets
3-stage spray tower 1 set
Dimensions 2000 mm (D) x 13m (H)
Sulfur oxide Less than 30 ppm (scrubbing with caustic soda)
Percentage of removal Higher than 90%
(dust concentration at the exit 0.2g/Nm3)
Vertical wet-type
Dimensions 3016 mm(sq) x 10900 mm (L)
Volume of gas treated 20,000 m3/hr (at 40°Q
Percentage of removal Higher than 90 % for the containing
0.2g/Nm3-DG at the entry
Direct heating type
Volume of gas treated 1 7 ,000 Nm3 /hr
Temperature of treatment For deodorizing
Maximum
Combustion capacity Large burner
Small burner
Height 45m
Material SUS304
1 set
1 set
750°C
800°C
3,000,000
kcal/hr
300,000
kcal/hr
I set
                                                92

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     Figure 1-1 shows the general plan of Kanazawa sewage treatment plant; Figure
1-2 the layout of the sludge incinerating facility; Figure 1-3  their flow chart, and
Table l-l their summary.                          ,,
                                                      (         Hokubu 1st S.T.P
                                            Midori S.T.P* J Kohoku s* p >   w, „  • '
                                                                  I
                                                      \-      , Hokubu 2nd S.T.P,
                                                         1 Kanagawa S.T.P    '>R'
                                                                  Chubu S.T.P
                                                                    Nanbu S.T.P
                                                                    Kanazawa S.T.P
                                          Seibu S.T.P
                                         Fig. 1-4   Transportation route of sludge cakes
1.2 Characteristics of facility
 a. Receiving storage and supply facili-
    ty of sludge cake
    Since   sludge   cakes  (SC)   from
    several  sewage treatment plants are
    to be transported to and treated by
    the incinerator, it  was decided to
    install   a  facility  for temporarily
    storing  different  kinds  of cakes
    from  different  treatment process
    and  dehydrators  and  to  supply
    them  at a constant input rate. A
    tentative route of transportation of
    SC is shown in Figure 1-4.
 b. Scrubber   wastewater   treatment
    plant
    The operation of wastewater treat-
    ment  at  Kanazawa sewage treat-
    ment  plant  was scheduled to be
    started  after 3  years, and it was  decided  to  install a treatment plant for the
    exhaust gas scrubber effluent water.
 c.  Automatic control system
    It was expected  that the sludge incineration facility under consideration would
    require  a  far larger number of control works (such as checking the amount of
    SC received  and stored, controlling the combustion  conditions in accordance
    with the change in properties of SC, and controlling the operating conditions in
    the scrubber wastewater treatment plant) than with ordinary type sludge incine-
    rators.  Hence, it was decided to introduce micro- and sequence-controllers and
    to adopt supervisory and control  to  enable each piece of equipment to fully
    perform its function and to reduce the amount of operating and control works
    to the  minimum through the insorporation  of  automation and  labor saving
    devices.
 d.  Energy saving
    It was  planned  that at the initial stage of operation the facility would entirely
    relay on city gas (LNG) and to convert to digested gas when the sludge anaerobic
    digesters at Kanazawa sewage treatment plant are completed.
    Since the facility was required to bum and deodorize its exhaust gas for main-
    taining environmental conditions in its peripheral areas, it was decided to install
    a heat-exchanger, which  preheats  the  exhaust gas to be treated by use of the
    deodrized gas, to economize in the fuel used for the afterburner. Also, it was
                                         93

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     planned to secure stable combustion conditions and to save the supplementary
     fuel by automatically controlling the volume of secondary air on the basis of
     the temperature at the exit of the scrubber.

1.3  Outline of each facility
1.3.1  Facility for receiving, storage and supply of sludge cake
 a.  Receiving equipment
     A  truck  weigh-bridge was  installed  to accurately account for the weight of
     sludge cake received  from each sewage treatment plant, ash produced  at the
     sludge incinerator and sludge  produced at  the  scrubber wastewater treatment
     plant.
     Figure 1-5 shows the flow of  operation at  the weigh-bridge. At  the  weigh-
     bridge, the car number  of  each incoming truck is read  by a card reader, and
     receiving and  shipping slips are printed  out. A micro-controller reads the truck
     number,  the  kind,  weight and source of sludge cake and transmits the data to
     the central control room, where data is sorted, totaled and printed by a logging
     typewriter.
                                    o Truck stops on the weigh-bridge
                                    o Truck driver inserts a plastic card with
                                      prepunched truck number into card reader.

                                    o A button is provided for each kind of material,
                                      dewatered cake, ash, scrubber wastewater
                                      sludge and tar. Truck driver depresses appropriate button
                                    o Truck number, weight and kind of material are transmitted
                                      to the micro-controller.  Data from the micro-controller is
                                      printed by dot printer
                                    o Departure signal "ON" is lit.
                                    o Card is pulled out.
: Start )
i
Incoming
Truck arrives
1
Inserting of
Truck No. card
i

/
Depress "kind of /
material" button /
ON |
Depress weighing
instruction button

___- 	 Print out - — ___
/
. NO
                    LYES
Departure
OK
            c
 END
                    Fig. 1-5   Flow diagram of truck weigh-bridge operation
     There are two modes to control the weigh-bridge:
     (£> The  weight of transported sludge  cake is  calculated  from the difference
        between the weight of the loaded truck and that of the empty truck which is
        registered  beforehand. This made requires the truck to be weighed only once
        and is more convenient.
     (2) The  weight of transported sludge  cake is  calculated  from the difference
        between the weights of the truck  before  and after unloading. This made
        requires each incoming truck to be weighed twice.
        Under normal conditions the single weighing mode is used.
 b.  Storage equipment
     ® Receiving  at the pit
        Sludge cake dehydrators at sewage treatment plants are operated only during
        daytime and  are stopped throughout the silent hours, Sundays and holidays,
                                      94

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         while the multiple-hearth furnace should be operated continuously (24 hours
         a day)  even on Sundays and holidays. It was decided to install a storage pit
         capable of storing dewatered  cake for 2 days operation, i.e., 250 m3 (effec-
         tive).
         Five gates to  the pit are provided for access by incoming trucks. To receive
         weighed  sludge cake in the pit, the destination is selected from 5 gates and is
         indicated by  a  flashing signal at the gate and  the gate is made "OPEN".
         The destination is automatically determined on the basis of the amount of
                  Is weighing
                  going on at the
                  truck weigh-bridge
                                     In sequence of
                                     desending oder of
                                     cakes accumulation
                           In sequence of a seconding oder
                           of cakes accumutatipnl
                                                           o  Control timing of ON for signal,shutter
                                      Prepare sequence
                                      table in descending
                                      order
                    Prepare sequence
                    table in ascending
                    order
Set cycle
sequence
                                     Upper limit
                    Changing    \^  level of pit
                    sequence timing
                    what mode?
Number of
I rucks
entered
Is number of trucks
entered previous
"Green" signal gate
equal to that
prescribed
                                       s pit level of
                                      previous "Green"
                                      gate equal to
                                      upper limit level?
                                                          o  Initiation of control program for signal
                                                            and shutter
                                                          o Decision of mode for sequence
                                                            (pre-determined)
o Prepare sequence table
                                                           o  Decision of mode of timing for
                                                              changing sequence (pre-determined)
                                                       o Decision for control by signal "Green"
                                                         shutter "OPEN"
                                                          o  Signal "Green" or shutter "OPEN" control
  (   End   )
                       Fig. 1-6   Flow diagram of signal light and shutter control
                                                95

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                                                   Transportation ioutf>
    sludge cake  accumulated in  each  section of the pit, number of the trucks
    waiting for unloading and the operating conditions of the crane.
    The control  flow diagram at the pit station is shown  in Figure 1-6, and the
    plan of receiving and storing equipment in Figure 1 -7.
(.2)  Transfer to the cons-
                                      Truck weigh
    tant rate feeder
    The sludge cake stor-
    ed in the pit is trans-
    ported  to  the cons-
    tant    rate    feeder
    operated automatical-
    ly   based   on   the
    amount of cake stor-
    ed at the feeder, and
    that  stocked  in  the
    pit, and on the pre-
    sence   of  incoming
    trucks.
    Four control  modes
                                     o=
                           Fig. 1-7   Plan of receiving and storage facility
are provided to disperse and stratify the control functions as follows.
1) Manual mode
   In this mode  the  equipment is manually operated by an operator in the
   crane operation room.
2) Automatic control mode at the site
   In this mode, the operation of the crane is automatically controlled by the
   sequence  control and the setting of the pinboard in the crane operation
   room.
   The pit is divided  into 18 addressed sections determined from the size of
   the grab of the  crane. The crane moves to the addresses in the sequence
   determined by the pinboard setting, skipping the address in which cake is
   being unloaded from a truck.
3) Set point control mode [I]
   Address setting  of the automatic control is performed by a high order
   micro-controller instead  of the pinboard at the site.  In this  mode, the
   sequence  of crane destination is automatically controlled on the basis of
   the  data  of signal control (indication of truck destination) and on the
   stocked amount of sludge cake at  each address so that conflict between
   the destinations of the crane and trucks may be avoided.
4) Set point control mode [II]
   In  this mode, corrections to the  braking instruction  to  the crane are
   added to the set point control [I]  and this is the highest level of control.
   Without frequent  manual adjustment  it is difficult  for the brake of the
   crane  to stop accurately at the designated position. Thus the corrections
   to the braking position are made automatically in units of  5 cm. Normal-
   ly, operation is conducted by this mode.
                                  96

-------
                    C   Siart    3
                           YES
'" "." /\ Setc
Mjnual NOAutomatic control -cont
uperdtion — 'mode at site vMod
(YES f
Consta
omt _
e°ll]
Set point
control Modelll]


ntrateNO

                                                                                                    to braking and output
                                                                                                    from microcontroller
                                                                                                    «	
                                                                  Detect by  x
                                                                  limit switchN position'
Origin is above constant
rate feeder is
After confirmation of
destination address,
move on the pit
                                                                              Pr'icnbed  ND  I Outside disignatedl
                                                                            < ^JAagJ Positro" alarm   |


                                                                                  [YES          I	*	1
                                                                                  Jl              I  Stop crane   I

                                                                              Incoming.   Lower grab, suppress lowering if truck
                                                                              truck'   *  is admitted in corresponding pit.
          Detection by  /Brake\NO
          limit switch   Nposiiion?
                                            Compute correction
                                            for  braking and
                                            output from
                                 Instruction  microcontroller
                       Stop
                       traversing
                       Presc
            A         ,	,
             scribed NQ  J   Outside stop  I
             ution?       "   position alarm J
                        XES
Advancing^ Direction.          I
         ^of run7

             ^t^Hetrogression
                                           Stop crane
                                                                            Return to        Return to constant
                                                                            original position)  rate '•"•f °" same
                                                                           —    I        '  route as outward
  Advancing
  start run
          Retrogression
          start run

                                                                                            route a
                                                                                            route.
     NO  Constant rate
2 *      "feeder level "»'">
                                                                                   YES
                                                                           C
                         Fig. 1-8    Flow diagram of bucket crane control
                                                          97

-------
                          Table 1 -2   Control functions
—- — Mode of control
•3g
£e
Automatic Dec's
on Element
Wired relay sequence
Sequence-controller
Micro-controller
State of constant
rate feeder
State of storage pit
State of signal
Presence of incoming
truck
Stop position
Manual
O
-
-
X
X
X
X
X
Automatic
control at
local station
0
o
-
o
X
X
o
Fixed
limit
switch
Set point
control [I]
O
0
0
0
o
o
o
Fixed
limit
swilch
Set point
control [II]
O
O
O
o
o
0
0
Compute by
micro-controller
Provide correc-
tion to brake
          Control  flow of the bucket crane and control functions are  shown in
          Table 1-8 and Table 1-2 respectively.
 c.  Supplying equipment
     Sludge cake is  supplied at a fixed rate from a constant rate feeder to the incine-
     rator by a conveyor.
     A conveyor weighing unit is  installed on the feed conveyor to keep the amount
     of sludge  cake at a fixed rate by controlling the speed of the constant  rate
     feeder.

1.3.2  Sludge incinerator
     Sludge cake is  fed through the opening at the top of the incinerator,  dried and
preheated as  it passes from hearths  1 to 4, incinerates at hearths 5 and 6,  cooled as
hearths 7 and 8, and taken out as ash from the bottom.
     The temperatures inside the incinerator are  maintained constant by a micro-
controller, which automatically sets the maximum temperatures in hearths 4 through
6.
     In addition,  the following modes  of control can  be used for  controlling the
temperatures  inside the incinerator.
 a.  Control for raising temperatures
     This mode is used when the  temperatures is raised to the incinerating tempera-
     ture, 800°C, after starting from the relighting stage of an idle incinerator.
 b.  Control for preserving temperatures
     This mode is used when incinerating operation is switched to that of preserving
     the temperature at 500°C.
 c.  Control for lowering temperature
     This mode is used when the incinerator is shut down.
 d.  Control for maintaining temperature at a fixed point
     This mode is used for controlling the temperature of hot air generated by auxi-
     liary burners at 1000°C.
     Control  valves  are  installed on the gas line to the burners and  on the air  line.
The  control valve on the gas  line is controlled by the temperature inside the incinera-
tor and the air control valve is controlled to keep the temperatures of hot air from the
                                     98

-------
auxiliary burners constant. As a result the incinerator body is protected, and clinker
is  prevented. At the  initial stage  of operation, the amount of secondary air was
manually  controlled to suit  the combustion conditions.  This method of  control,
however,  tended to increase the proportion of air. At present  it is automatically
controlled.

1.3.3  Exhaust gas treatment plant
 a.  Scrubber
     This is a three-stage spray tower for cooling, dehumidifying, removing dust from,
     and desulfiirizing the exhaust gas discharged from the incinerator.
     The amount of caustic soda supplied to the recycling  tank is controlled by the
     pH of the overflowing water.
     The concentration of sulfur oxides should be less than 30 ppm at the exit of the
     tower when the concentration at the entry is 300 ppm. The removal rate should
     be higher than 90 percent. The  amount of water supplied  to  the scrubber is
     controlled so  that the temperature of exhaust gas at the exit of the tower may
     be maintained at 40° C.
 b.  Electrostatic precipitator
     A wet vertical type electrostatic precipitator is adopted, since it requires less
     floor space  to install and less volume than a dry type. The concentration of dust
     at the exit of the collector should be less than 0.02 mg/Nm3.
 c.  Afterburner
     This is required to deodorize the exhaust gas and to prevent white smoke. The
     reaction temperature should be 800°C at the maximum and the  set temperature
     can  be readily maintained by controlling the combustion of burners. A  heat
     exchanger is installed to preheat the gas to be deodorized with heat from the
     exhaust gas.

1.3.4  Scrubber wastewater treatment plant
 a.  Pilot  plant experiments
     The scrubber  wastewater contains dust from the incinerator dissolved substances
     from dust, salts of sulfur oxides in addition to various metals in a low concentra-
     tion.  The following experiments  were conducted to select the best process for
     treating the scrubber wastewater from the two prospective processes, i.e., ferrit-
     izing  and chemical sedimentation.
    ®  Quality  of water to be treated
        The sample used in the experiment was the wastewater obtained by scrub-
        bing the gas from  the  pilot  plant incinerator. The cakes incinerated were
        produced  by  vacuum filtration and centrifugation at Nanbu sewage treat-
        ment plant and by pressure filtration at Totsuka second plant. Since the
        concentrations of metals in some samples  were very low, the experiments
        were conducted on  the assumption that the wastewater  contains metals in
        the concentrations shown in Table 1 -3.
        The values in  the table were determined by referring to the examples of
        measurement, published in Japan.
                                      99

-------
                  Table 1-3   Metals contained in scrubber wastewater
-~-^Jtem
Cone, in
wastewater mg/fi
Target mg/e
SS
414
COD
40
70(^)1 25
Cd
0.27
0.1
T-Cr
2.26
2.0
Cu
3.29
1.0
Ni
0.56
1.0
Pb
1.00
1.0
Zn
16.55
1.0
Mn
5.44
1.0
Fc
197.6
3.0
T-Hg
0.07
0.005
      Note 1.  Target values of treatment are based on the standards of wastewater specified in the
             pollution control ordinance of Kanagawa Prefecture.
     '  Experiments on treating by ferritization
       After basic data was obtained by  bench scale tests, experiment were con-
       ducted  in  accordance with  the flow diagram shown in Figure 1-9. Ferritiz-
       ing was found to be ineffective with copper, although it could remove metals
       other than copper.
       Formation of ferrites depended on the ratio of the amount of iron added to
       that of suspended solid (SS) present in  wastewater.  A good yield of ferrite
       could  be  obtained  only under  conditions  satisfying the following  ratio;
       SS/FE
-------
         Experiments on treatment by chemical sedimentation
         After basic data on the kind of coagulant, the amount of addition, and so on
         were obtained by jar tests, experiment were made according to the flow dia-
         gram shown in Figure 1-10. Using ferrous sulfate as the coagulant at a con-
         centration of 300 to 500 mg/2 at a pH value of 9.5 to 11, the concentration
         of metals other than copper was reduced to less than the desired values. The
         addition of 300 to  500 mg/£ of ferrous sulfate to the wastewater contain-
         ing 350 mg/£ of SS, gave about 500 mg/£ of sludge.
              Sludge cake
                   50 kg/hr
  Kerosene
  17.6ii/hr
 Water
 09 m'/hr-
Caustic soda-*
(NaOH)
300g/hr
                                    Metals
                                    Ferrous Sulfate
                                    (FeSO4-7 H,O)
                                    300-500 rng/C
                                    Caustic soda
                                    (NaOH) 250 mg/C
                                         or
                                    Calsium hydroxide
                                    (Ca(OH),)250mg/e
                                    polymer
                 Fig. 1-10
                                                                Sulfuric acid
                                                                (H,SO4)
                                                                320 K/hr
                 .  Treated water
Flow diagram of chemical sedimentation pilot plant
     (4)  Experiments using
         chelating agents
         Jar test experiments for
         removing copper the un-
         wanted  substances  by
         use of a chelating agent
         were  conducted  under
         the following conditions:
        Cone, of ferrous sulfate solution
                    500 mg/8
        Cone, of caustic soda solution     c
                    250 mg/e        <3
        pH value at the time of precipi-
        tation        7.1
        Formula of chelating agent
               (CH3)2NC-SNa(M.W.143)
                       II
                      S
                        Chelating agent  (CH3)2NC-SNa

                        Stirring time : 30 mm.   S
                        Stirring speed: 9O rpm
                                    ©Cu
                                    AlSli
                                    u Zn
                                    > Pb
                     12345
              Ratio to the theoretical amount of addition of chelating agent
             —	,	,	,	,	
                      10         20        30        40
                       Amount of addition of 40% chelating agent (mg/8)
            Fig. 1-11   Removal of metals by chelating agent
                                              101

-------
       Most of the  copper could  be removed by using 30-40mg/C of chelating
       agent (about  4 times the theoretical value). It was decided, however, duct
       filtration  should be provided  by a sand layer at the final stage before  dis-
       charging the treated water, since the floe produced was very fine. The results
       of the experiments are shown in Figure 1-11.
   (§'  Determination of treating process
       The ferritizing process was not considered suitable for use against the waste-
       water used in the  experiment, because it could  not remove copper and it
       produced about 9 times as much solid sludge as the chemical sedimentation.
       It was  decided to adopt  chemical sedimentation as the principal process,
       taking into consideration such factors as the effect of treatment, economy,
       and the stability of operation, and also to install a "chelating and sand filtra-
       tion process" for the sake of safety.
       Further, it was decided to process the sludge by  pressure filtration without
       the addition of any chemicals, since the sludge consisted almost entirely of
       inorganic precipitates.
b. Actual plant
   The  design specifications of  the  scrubber wastewater treatment plant are as
   follows:
   ®  Process                         Chemical sedimentation and sand filtration
   ©  Capacity  sulfate                   120m3/hr
   (I)
Process
Capacity sulfate
Chemicals requirement
Ferrous suflate (15% cone.)
Caustic soda (48% cone.)
Polymeric coagulant (1% cone.)
Sulfuric acid (75% cone.)
Sodium hypochlorite (12% cone.)
Dehydrator
Capacity
                                         400 ppm
                                         250 ppm
                                            1 ppm
                                          60 ppm
                                          80 ppm
                                         3.5 cake-ton/day (water content 70%)
    The flow chart of the scrubber wastewater treatment plant and the summary of
    equipment are shown in Figure 1-12 and Table 1-4 respectively.
    Since  the scrubber wastewater is discharged from the scrubber at a temperature
    of between 50° to 60°C, it must be cooled by the cooling tower before it is fed
    into the receiving tank. Then, it is pumped into the reaction tank, where ferrous
    sulfate solution is added in proportion to the rate of flow, and the mixture is
    agitated.  Then it is fed into a conditioning tank to adjust pH to  9.5 by adding
    caustic soda.  The  resultant floe is further  flocculated by  adding polymeric
     Scrubber
     wastewater
                   Caustic soda
                Ferrous  i  Sodium hypochlorite
                           Polymer
                                '
                                                     Distributing tank
      1 Cooling tower
                        9 Sand filter
      2 Receiving tank of scrubber  10 Neutralizing tank
        wastewater
     3  Reaction tank
     4  pH controlling tank
     5  Polymar mixing tank
     6  Settling tank
     7  Chelating tank
     8  Distributing tank
                 11  Sludge oxidizing tank
                 12  Thickener
                 13  Sludge feed tank
                 14  Pressure filter
                 15  Cake storage hopper
Sufunc
acid
                                                                   -f]V— Discharg
              Fig. 1-12   Flow diagram of scrubber wastewater treatment plant
                                     102

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              Table 1 - 4  Outline of scrubber wastewater treatment plant
Name
Reaction tank and
pH controlling tank
Polymer mixing
tank
Settling tank
delating reaction
tank
Sand filter
Neutralizing tank
Cooling tower
Sludge oxidation
tank
Sludge thickening
tank
Dehydrator
Description
Holding time:
Effective capacity:
Mixing time:
Effective capacity:
2.S min, 2 groups x 2 tanks
2.5m (sq) x 2.5m (H)=6.25m3/tank
1 min , 1 tank
2.5m3
Settling time: 3 hours, 1 tank
Overflow rate: 1.5m3/hr
Capacity: 530m3
Circular center-driven type
Holding time:
Effective capacity:
2.5 min. 1 tank
6.25m3
Filtering speed: 7m3 /m1- hr.
Effective filter surface: 21.4m1
Gravity type with automatic reverse washing.
Holding time:
Capacity:
Capacity:
Liquid temp.:
Atmospheric air temp.
Blower capacity:
Holding time:
Capacity:
Detention time:
Capacity:
Solid loading:
Picket fence type
Filter area
Filtering pressure:
Number of filter
chambers:
Pressure filter
2.5 min.
7.2m' x 2 tanks
ISOm'/hr
Entrance 60°C, exit 40°C
Wet bulb temperature 27" C
2900m3/min x 7 mmAq
15 hours
14m3 x 2 tanks
7 days
210m3 x 1 tank
50 kgDS/m2 day
148m1
9.9 kg/cm2
60 chambers
     coagulant into the mixing tank.
     The  effluent from  the mixing tank is fed into a settling tank and the SS is
     removed by precipitation. The resultant solution is fed into a chelating reaction
     tank. No chelating  agent, however, is  added  in  normal operation.  If the con-
     centration of copper is high, a chelating agent  will be added and the resultant SS
     will be removed by a sand filter down to a concentration of about 10 ppm.
     After the measurement is taken on the volume, the filtrate is fed into a neutraliz-
     ing tank to be neutralized to pH7 by adding sulfuric acid, and then it is discharg-
     ed.
     The sludge separated by precipitation in the settling tank to the concentration of
     about 5% is fed to a sludge oxidation tank, where ferrous oxide contained in the
     sludge is oxidized to ferric oxide by blowing compressed air into it.
     The  sludge is  further fed into a sludge dehydrator after it is concentrated to a
     concentration of 7% in a sludge thickening tank.

1.3.5  Automatic control system
     One  micro-controller set and two sets of sequence-controllers are used to ensure
intensive and flexible automatic control. To support control equipment, wired-relay
circuits for  direct  control by operators and  lower-level  automatic control using
regulators for S.C.C. (supervisory computer control) are provided. The configuration
of the automatic control equipment is shown in Figure 1-13. In addition to the fully
automatic control mode, modes of interlocking operation by blocks are provided for
the period of running-in  operation and anticipated  partial breakdown of the facility.
These conceptions of automatic control are  shown in  Figure 1-14. The instrumenta-
tion and items of control  throughout the whole system are listed in Table 1-5.
                                       103

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Table 1-5   Overall instrumentation and control items
System
1. Receiving, storage,
supply of sludge
cake























2. Incinerator




3. Exhaust gas
treatment







4. Scrubber waste-
water treatment




Control item
(1) Control of operation of
truck weigh-bndge.





(2) Shutter signal control








(3) Control of crane







(4) Control of feeding of
cake.
(1) Pressure control
(2) Temperature control


(3) Combustion air control
(1) Control of scrubber

(2) Control of electro-
static precipilator
(3) Control of after-burner




(1) Control of scrubber
wastewater treatment
plant



Outline of contents of control
(1) Computation, sorted and printing or receiving
data, classified by treatment plant.
(2) Issuring of receiving and shipping slips.
o Truck No. day and time, total weight, tare, net
weight.
(3) Detection of incoming trucks
o Instruction for shutter signal control.
(1) Decision on the corresponding pit level from
among gates 1 thru 5.
o Decision on priority sequence.
o Instruction for opening of corresponding gate
to incoming truck.
o Instruction for "green" signal to incoming truck.
(2) Detection of admission of truck
o Instruction to bucket crane on susppression of
descent to the pit corresponding to the gate.
(1) Decision on the weight of constant feeder
hopper.
o Instruction to the crane on starting operation
( 2) Decision of destination address
o Memorize level of each address of pit.
o Decision of admission of a truck to gate.
(3) Instruction to the crane on traversing, traveling
and grabbing.
(1) o Constant feeding of cake
o Consideration to idle time.
(1) Constant control of pressure inside incinerator.
(1) Control of raising and lowering of temperature.
(2) Control of hot air temperature.
(3) Control of constant temperature inside incinerator.
(1) Control of secondary air volume
(1) Control of constant pH
(2) Control of exhaust gas temperature at the exit.
(1) Control of voltage and current

(1) Control of constant deodorizing temperature.
(2) Control of temperature for white smoke pre-
vention.
o Decision of temperature to prevent white smoke
referring to humidity chart.
(1) Control of flow of untreated water.
(2) Control of rate of addition of ferrous sulfate.
(3) Control of constant pH in pH control tank
(4) Control of rate of addition of polymer solution.
(5) Control of rate of addition of dictating agent.
(6) Control of constant pH at neutralizing tank.
                        104

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                Substation                   Substation
                 I     "|	Data way	i       i
      .. 1 \   ;
                                                                ON
         Common
                                                     Incinerators
                      Fig. 1-13   Configuration of automatic control equipment
                                                                                      	i
                                                                                   Scrubber wastewater
                                                                                  ^a	Bp4
                         ^j-Fullyai
 Fully automatic
 operational
 condition
Blocked linkage ON switch

                Block6u i  .i "*-»*-"• — '<—
                linkage  °/cos      |
Minimum
operational
condition
                                utomatic ON switch

r *"
b !
Fully 	
i automatic
Same
as left

— O 0 —

J_
UINC
~ni,
Same as
r left
b



P
~1


bd
I,

i
b

                                                     cos
                                         Same as
                                         left
                                                B
                                                Block
                                                                                 cos
                      I	1
                                                  I	
     Block diagram of incinerating facility — water supply pump, cake feeding, operation of incinerator, auxiliary
     burners, scrubber, electrostatic precipitator, induced draft fan, afterburner, ash storage.
     Block diagram of scrubber wastewater treatment plant — raw wastewater pump, ferrous sulfate
     polymer, chelatirtg agent, reaction tank agitator, settling tank scraper, sludge thicker, dehydrator sulfric acid,
     cooling tower.
            Fig. 1-14   Concaptional diagram of "Fully automatic" and "Block linkage"
                                                    105

-------
1.4  Present state of treatment
     operations
     Although  several new concep-
tions,  which  have few  records of
performance,  such   as,  integrated
treatment  of  sludge  cakes   from
various  sources   and independent
treatment  of scrubber wastewater,
are incorporated  in  the  system, no
serious difficulties have been encoun-
tered so far.

1.4.1  Sludge incineration
     The results of sludge incinera-
tion in  fiscal  1980  are shown in
Table 1-6.
Table 1-6  Performance of sludge incineration
	 	
Amount incinerated t
Ash
Fuel
Amount t
Rate of production %
Water content of ash shipped %
Incineratoi
After
burner
Total
Water
Caustic soda
Electric power
Amount used m'
Per ton of cake m3 /t
Amount used m3
Per ton of cake m3/t
Amount used m3
Per ton of cake m3/t
Amount used m3
Per ton of cake m3/t
^Amount used t
Per ton of cake kg/t
Amount used kWH
Per ton of cake kWH/t
Time of operation of feeding conveyor hr
Fiscal 1980
32,171
3,386
10.5
24.9
701,688
21.8
714,451
22.2
1,416,139
44.0
•438,154
13.6
185
5.8
1,613,425
50.2
7,192
Type of
Dehydrator
Total
CF
BF
PF
Amount produced and incinerated
32,000t 79,600t
Incineration j fj ]
24,740t 51 .600t
Incineration ] fj ]
5,1 20t
Inc. \ 4-6.520t
2,1 40t 21,380t
M I

Percentage
of
production
100%
64.9%
8.2%
26.9%
Percentage of
amount incinerat-
ed to amount produced
40.2%
47.9%
78.5%
10.0%
            .                            Fig. 1-15  Amount of dewatered cake produced
 a.  Properties of sludge cakes                     and incinerated in f isca,,980
     The amount of sludge cake produced and incinerated in fiscal 1980, classified by
     the process of dewatering are shown in Figure 1-15.
     Three kinds of dehydrator, vacuum filter (BF), pressure filter (PF), and centri-
     fuge (CF) are used in this city's sewage treatment plants.
     Of about 79,600 ton of sludge cake produced  in  1980, 32,000 ton were inci"e-
     rated and the rest were disposed of by reclamation. Incinerated cakes were the
     sludge  cakes from  CF which were  of the kind ill-suited for handling,  because
     they  contained a high percentage  of water  and  had a strong odor. The yearly
     average water content and calorific value of the mixed sludge cakes were about
     76% and 2500 kcal/KG-DS, respectively.
 b.  Properties of ash
     Since ash is comprised of fine particles and does not contain water, it tends to
     scatter  into  the air when it is discharged from the incinerator. It is humidified
     (to a water content of about 25%) before transportation.  The ratio of the weight
     of humidified ash to that of sludge cake is about 1  to 7.
                                 106

-------
      Table 1 -7   Results of analysis of exhaust gas
Item
Volume ot dry pas NmJ/hr
0,
Dust g/NmJ
SOX 
-------
   to 5.32 ppm, it was decided to add sodium hypochlorite in the reaction tank.
        Accordingly, the scrubber  wastewater is at present pumped back to the sewage
   treatment plant after being conditioned to pH 9.4, having the cyanide removed and
   being neutralized.

   1.5  Results of operation
   1.5.1  Operating process
        Receiving gate  indication  for  trucks and automatic  control  of  bucket crane
   operation have been going on quite satisfactorily.
        Although suspension of operation of the constant rate feeder due to over-load
   caused by blocking of the spiral-blades of the conveyor by foreign matter mixed in
   sludge  cake have  occurred  a few  times  each year,  improvements, which will  be
   described later, enabled expedite elimination of obstacles and maintaining of smooth
   operation.
        Sludge  incinerator was operated under constant temperature control (800°C)  by
   use of auxiliary  burners. However, the spontaneous  conbustion phenomenon took
   place 5 to 6 times a month, 20 to 30 hours in total.'This phenomenon is commonly
   seen in  plants which treat  mixed  cakes  from various sources. It was possible to
   maintain the temperature inside the incinerator constant (set at 830°C) even when
   temperature tended to rise by spontaneous combustion, by automatically controlling
   the cooling damper device. Figure 1-16 shows the temperature at various parts in the
                r100 T
Degree of openess
of cooling damper
Volume of gass
for auxiliary burner
Degree of openess
secondary air damper
Temp, at
6th hearth
Temp, at
5th hearth
Temp, at
1st hearth
                       L
_L
                                   10
                                            12
                                                 13
                                                     14
 15
_l	
                                                              16
                                                                  17
                                                                      18   19   20   21
                      Fig. 1-16  Time-chart for controlling incinerator
                                        108

-------
     NOx
     SO,
Temperature of
afterburner
pH at
scrubber
Pressure
inside
incinerator
r 200

  100

(ppm)
-  0
r 100

   50
(ppm)
   0
r 800

  750
  (°C)
L 700
r12.0
  6.5

- 1.0
r 50


   0
 mnAg)

 -50-
                  7    9   9    1.0   II   12   13   14   15  16   17   18    19   20   21
                  I	1	1	1	1	1	1	±	I	I    I   -- I    I    i     |
                  Fig. 1-17   Time-chart for treatment of exhaust gas

incinerator under normal conditions,  flow of auxiliary burner gas, and a time chart
indicating the operation of dampers.
     In the exhaust gas treatment plant, stable operation could be maintained by the
automatic control equipment for maintaining constant pressure inside the incinerator
(-6 mmAq)  by the furnace pressure control damper, constant pH at the absorption
cooling tower (pH 6.4), constant voltage at the electrostatic precipitator (50 kV),
and constant temperature inside the deodorizing furnace (800°C). Figure 1-17 shows
the time chart of exhaust gas treatment operation.
     Operation of the ash conveyor and the whole incinerator had to be suspended
several  times because  foreign  matter? mixed  in the  cake  blocked the  conveyor.
Increasing the water content of ash to 25 percent facilitated the transportation of ash.
     Functions of various kinds of control equipment incorporated in the scrubber
wastewater treatment plant were quite  satisfactory.

1.5.2  Rate of operation and load factor
     The state of operation of the facility is shown in Figure 1-18. The rate of opera-
tion of the facility throughout fiscal  1980 was 90.6 percent and the rate of suspen-
sion due to power and water failures was 0.1 percent, and that due to breakdown of
equipment and  excessive  rise  in  temperature was  0.3 percent.  The  load factor
throughout fiscal  1980 was  108.7 percent. The fact that the facility could operate

-------
                                          Suspension due to break •
above  the  rated load factor  IS credited tO  down, excessive rise in  Suspension due to powe. and
the  Stable  Operation  brought  abOUt  by  temperature and soon,  water failures and so on
                                          i(J.o/u)             IU. I /o)
automatic  control notwithstanding incine- T
                                          Suspension due
ration  of various kinds of sludge cakes and  to regular
to the control of the secondary air which  Inspectlon-.
yielded surplus capacity of the exhaust gas
treatment  facilities including the  induced
draft fan.
1.5.3   Improvements
    After commencement of operation of
the facility,  the  following improvements Fig. 1-18   State of operation (Fiscal 1980)
were incorporated to solve the difficulties brought about by the mixing of foreign
matter in the sludge cake, to economize in energy usage,  and  to maintain  stable
operations of the whole facility.
 a. Improvement of the constant rate feeder for saving difficulties caused by the
    mixing of foreign matter
    Figure 1-19 shows the improvement in the constant rate feeder.  In  the running
    in  operation prior  to full-scale operation, foreign  matter, such as, concrete
    lumps, pieces  of  steel pipe,  and empty cans, caused the overload  protection
    device to actuate several times and also resulted in deformed screw shaft and
    broken bearing cases and finally the suspension of operation of the whole incine-
    rator.
    Equipment was improved to make the conveyor less liable to damage and more
    readily repairable so that  operation could  be resumed without  serious difficul-
    ties.  In order to prevent foreign matter form blocking the screw conveyor, the
    intervals between the  spiral blades were made longer and the clearance between
    the blades and the bottom plate was increased to  about 200 mm to allow foreign
    matter to fall to the bottom.
    To eliminate difficulties before they result in suspension of operation the driv-
    ing mechanism of the conveyor was divided into 3 sections so that each section
    may  be broken down and checked separately. By virtue  of the improvement, no
    suspension of  the feeding operation to the incinerator  occurred, although the
    over-load protection device was actuated three times.
    Also, improved equipment allowed faster repairing work. At  the annual cleaning
    of the constant rate feeder, foreign matter with a total volume of  0.1 m3  was
    taken out of the bottom of the conveyor.
 b. Improvements in energy saving and securing of stable operation
     Improvement in the control of secondary air is shown in Figure 1 -20. Originally,
    secondary air was controlled  manually by an operator who monitored the tem-
    perature  inside the  incinerator and adjusted the volume of secondary air as a
    matter of experience. Although stable control of temperature could be attained
    by this  method, manual operation tended to make a  large allowance for the
    volume  of air, because  the facility treated various kinds of cakes  which were
                                      110

-------
Before the improvement
 Discharge
After the improvement

                                                                           8 axis, screws
                                                         Cake bunker
                                                                           3 pjirs of
                                                                           double
                                                                          . ax is screws
                                                      7 5 kW vs motors x 3
  Fig. 1-19   Improvements to constant rate feeder
      produced at different dewatering processes, consequently their quality varied
      greatly. Improvement  was made to limit  the volume of secondary air to the
      minimum to save both fuel and scrubbing  water and to stabilize the operation.
      In order to maintain the concentration of O2  in the exhaust gas at the prescrib-
      ed value a  cascad  type control system was adopted. The high order control
      system was  made to transmit the set value of the temperature of exhaust gas at
      the exit of the scrubber to the low order control system so that the temperature
      at the 2nd  hearth of the incinerator may  be kept constant, and the low order
      control system, which controls the secondary air damper, was employed so that
      the exhaust gas temperature at the exit of the secrubber may be maintained at
      the set value. As a result,  stable operation, which required the resetting of the
      2nd hearth temperature only once or twice  at the most, could be attained.
      As for the saving in operation cost, the improvement brought about the saving or
      fuel by 34  percent (¥95 million a year) and of scrubbing water by  25 percent
Table 1 -11   Comparison of results of operation before and after the inprovements in secondary air control
Items
Before improvements
After inpiovement
Rate of increase or
decrease
O2
About 12%
About 9%
-
Air
ratio
2.6
1.7
-
Volume of Gas
Auxiliary
burners
29.8 m'/t
17.6m3/t
-41.0%
After
burners
50.2 m'/t
35.2 m3/t
-30.0%
Total
80.0 m'/t
52.8 mj/t
-34.0%
Volume of
scrubbing
water
28.9 m3/t
21. 6 m'/t
-25.0%
Weight of
cake incinerated
96.3 t/day
107.5 t/day
+ 10.4%
                                         111

-------
       Before Improvements
Exhaust gas
	
i A' I


-
Burner
i 	 1 Incinerator

. ®° .
\:
2j
Vc 1
51
J


Axis cooling fan

— •- To stack
I/I 	 "• To scrubber
-L Motor
W"* ~" 	 Manually controlled by
__ 	 	 ». an operator who monitors
the temperature inside
incinerator from a remote
poistion.
Secondary air


       After Improvements
                   r
  Set temperature is
~ changed once or twice
r> a day by monitoring 02
I  concentration.
                                                        ToEP
            Burner
            OH
                    ®
                 Axis cooling fan
Fig. 1-20   Improvements in control of secondary air
     (¥51 million a year). Further, in order to save the cost of handling and disposal
     of ash (consignment  fee for disposal), an improvement was made on the spray
     nozzle to the ash humidifier resulting in an increase in spraying effect and reduc-
     tion of usage by about 29 percent (more than ¥4 million a year).

1.6  Costs
1.6.1  Construction cost
     Construction work on these facilities was started in July 1975 and it took about
3 years  before the facilities started operation.  Construction cost of the  facilities
including the sludge incineration and the scrubber wastewater treatment plant was
about ¥2,240 million.
     Details  of the  expenses
are listed in Table  1-12.

1.6.2  Maintenance and oper-
       ations costs
     The cost of incinerating 1
ton  of sludge  cake  in fiscal
                                            Table 1-12   Construction cost
                   Unit 1,000 yen
^-\_
Mechanical equipment
Electrical equipment
Construction works
Total
Sludge incineration
facility
773,000
320,500
482,200
1,575,700
Scrubber waste-
water
treatment plant
304,900
213,300
149,754
667,954
Total
1,077,900
533,800
631,954
2,243,654

-------
        1980 was ¥13,492 (utility cost ¥8,193), of
        which about 50 percent was fuel cost and
        16 percent was labour cost.
             If kerosene had been used as the fuel,
        the cost  of incineration would have  been
        ¥8,911 per ton (utility cost  ¥3,611  per
        ton).  The  cost  of treating the  scrubber
        wastewater  was ¥1,513  per ton of sludge
        cake, of which about  45 percent was the
        cost  of chemical and  42 percent was the
        cost set against depreciation.
             Details of operating costs are shown in
        Table 1-13.
  Table 1-13   Operation cost
TueT
Fleclrtc power
Total cost ol utilities
Repairs
n\tures£ expentiables

Ash disposal
Labour costs
Ucprec lalum
                                                    Cos! lor treatment of dewjtercd
                                                    cake (yen per ton)
                                                    Note I
                                                    Note 2
                                                    Note 3
                  Cost during April, 'SO
                  through Much '81
                   214:386.000
                    12.663.001)
                    31,811.000
                    (6.249,0001
                     3,307.000
                   (21,586,000)
                   262,167,000
                   (27,835,000)
                    11.317.000
                    9,148,000"
                      (39.000)
                    30,150,000"
                     (131,000)
                    71,015.000
                  " 47,9-75,000
                   (20.440.000)
                   431,772,000
                   (48,445,000)
                      13,492
                      (1,51!)
     luel  City (MS Y154 per Nm' (11,000 kc.il/Nm' I
     I lectric charges. ¥ 15 per kWh
     Basis of depreciation Residual puce 10';;..
                 Period of depteujition 20 vewis
Note 4  1 reated water is used tor scrubbing
Note 5  I ipurus in brackets indicate the cost ol scrubber
     wastewater treatment proce«
2.   Incineration of Sludge Mixed with Pulverized-coal in a Fluidized Bed System
     The construction of incineration facilities for pulverized-coal mixed with sludge
was started in December 1978 in the Hokubu second sewage treatment plant. It was
designed  on the basis of results obtained from  experiments conducted at the  pilot
plant from January to October in  1977 (presented at the 6th U.S/Japan Conference
on Sewage Treatment  Technology). The  plant  was completed in March 1981 and
went on stream after adjustment during a trial operation period.

2.1  Outline of incineration processes
2.1.1   Circumstances
     Conventional sludge incineration systems require a large quantity of oil energy as
the  supplementary fuel. The prevention of secondary pollution from these systems
should  also be considered concerning the exhaust gases and burned ashes generated in
the incineration process. The recent worsening of the oil situation makes it essential
to save energy by heat recovery etc., and to conserve oil by using alternative forms
of energy, and also to take effective countermeasures for preventing secondary pollu-
tion.
     To eliminate various problems associated with  the incineration of sludge,  pilot
plant experiments with a fluidized bed furnace were carried  out by using pulverized
coal as  a  supplementary fuel and cement clinker  as a fluidizing medium. Results  were
obtained  on the spontaneous-burning of sludge cakes, furnace bed load, SOx control,
O2  and NOx concentrations, CO concentration and inhibition of oxidation to hexava-
lent chromium, etc. These observations confirmed that the incineration system  with
pulverized-coal was effective and the process was adopted for practice.
                                       113

-------
2.1.2  Treatment process
     The  treatment process
of this incineration system
is   composed  of  feeding,
incineration,  exhaust  gas
treatment and ash disposal.
The  overall  plan  of  the
plant  is given in Fig. 2-1,
the  flow  sheet  in  Fig. 2-2,
the layout in Fig.  2-3, and
the  main equipment  speci-
fications in Table 2-1.
 a.  Feeding  and  incinera-
     tion
     Sludge cakes  and pul-
     verized-coal are simul-
     taneously metered into
     the kneader,  continu-
     ously mixed, and  fed
     into the fluid ized bed
     incinerator.       The
     kneaded  cakes are  fed
     into the furnace and
Table 2-1   Specifications of main equipment
Item of
equipment
Kneader
Pulvenzed-coal
silo
Pulveri7ed-coal
teed hopper
Incinerator
Medium silo
Medium feed
hopper
Double cyclone
Air preheaier
Waste-heat
boiler
Multi-cyclone
1 IcctTostatic
precipitalor
.Stack
forced draft
blower
Positive draft fan
Induced dratt tun
das recirculdtion
blower
Htirner air
compressor
Incombustibles
separator
Ash cooler
Ash bunker
Specification
Double-axle continuous type Drive Dnven =
2 1 rotation ratio 6t/h x 1 5 kw
Etfective volume 100m3 130-3060 kg/h \ 5 5
kw Discharger with pipe
Effective volume 1.5m' 250-1000kg/h \ 1.5
kw with constant [ate discharger
Kuidized bed furnace Sludge cake
lOOt/day *3400mm \ H 8000 mm
Effective volume 20m1 3t/h \ 1.5 kw with
discharger
Effective volume 0 2m3 300 kg/h x 1 5 kw
with feeder
Heat-resistant type 16. 2911 Nin3/h x 900°C
Vertical cylinder lype heat exchanger 14.500
Nm3/h Heating surface 146m2
Twin bodied natural cuuilatlon boiler 14,500
Nm3/h Heating surface area 420m1
Multi-cyclone lype)4,500Nm3/li x 300°C
Dry horizontal flow type 14,500Nm3/h \ 300°C
Outlet dust content 0.02p/Nm3 max
Stainless steel stack supported by iron tower
« 1,500 mm xH 30,000 mm
Turbo-blower 180m3/min (at 20"C) x 2.000mm
Aq x 3,000 rpm x 100 kw
Turbo-fan 150m' /mm (at 20" C) x 30()mmAq \
1,500 rpm x 15 kw
Turbo-fan 750in5/min (at 300"C) x 450mmAq
x 1500 rpmx 100 kw
Turbo-blower 70m'/min (al 300QC) x 1,800mm
Aq \ 3,000 rpm x 75 kw
Recipro-automatlc unloadcr type 5 Om3/mm
\ 7kg/cm'G x 37 kw
Amplitude type 200 - JOOkg/h (at 800 -
200 C) x 1 5 kw
Screw type conveyor with water-cooled jacket
200 - 1060 kg/h (at 600°O x 1.5 kw
I ffective volume 45m3 wilh ash humidifier
Q'ty
2
2
2
1
1
1
1
1
1
I
1
1
1
1
1
1
2
1
1
2
Remarks
I for spare
10 days' stoik
1 for sp.tre

10 days' nock


Inlet 8, H"C
On. Id 73U C'
Inlft 730 C
Outlet 11)11' C
6 cyclo nf\


Driven by steam
turbine & motor

Driven [)\ steam
turbine X niotot




days' stock
Secondary treatment --.
electrical machinery — -1
room — '
I
;'
=i
==
i=
Ftna
( - /
\
: -^
;E
\
=
7T~1_
settling 1
deration t
Primary


Jl 	
ank
ank
sett I i
LH
P
L 	
I
ng tank
4 	
l'-
i 	
                                                          Extra high voltage electricity substation
                                                          Central control room
 Fig. 2-1   Comprehensive layout of the Hokubu Second sewage treatment plant
                                    114

-------
                                 .Pulverized   i
                                 ;coal        'Medium
                                  conveyor    ; conveyor
                                                                                                         Waste water
                                                                                                                                   ihaust gas
                                                                                                                                      e>
                          —€>	 Cooling of all equipment
Circulating cooling Mains
water from all     water
equipment        supply
No
1
2
3
b
o
7
8
9
Item o1 equipment
Truck weigh-bride
Siudge cake storage pi!
Feed crane
Sludge cake constant rate feeder
Studge cake conveyor
Pulverf2ed-coal silo
Pu!ve'ized-coal feed hopper
Puivertzed-coalconstanirate feeder
O'ty
1
1
2
2
2
2
2
2
No
10
11
12
14
Ib
1b
17
18
Hem of equipment
Kneader
Fluidized bed furnace
Forced draft ^an
Kerosene tank
Kerosene p>jmp
Cooling water pump
Medium reception hopper
Medium sifo
Q'ty
2
1
1
1
2
2
1
1
No
19
20
21
23
24
25
26
27
Item of efluipment
Med'um teed hopper
Double cyclone
Air pr eh eater
Mutti-cyclone
Dry type electrostatic precipitator
Induced draft fan UDFJ
Steam turbine for IDF
Stack
Q'tV
1
1
1
1
1
t
1
i
No
28
?9
30
32
33
34
35
36
Item of equipment
Forced draft blower (FOB)
Steam turbine for FOB
Gas recirculation blower
Boiler raw water tank
BoMer raw water pump
Water purifying equipment
P.jre water tank
Better water feed pump
P' V







2
No.
37
38
39
41
42
43
44
45
Item of equipment
Incombustible separator
Cyclone ash cooler
Ash bunker
Ash humidifier
Circulation water tank
Water circulation pump
Recycled water cooling tower
Water reservoir
O'ty
1
1
2
2
1
2
1
t
                                           Fig. 2-2    Flow sheet of incineration facilities

-------
Truck weigh-bridge
control room
                   3F  Crane control room
                   1F  Machine room (fans)
                  ' Basement Water tank
                   room (pumps'
                      .Drainage neutralization
                       tank
52000
                                                 Roof Lower pressure condenser
                                                 3F Office control room
                                                 2F Sitting room power distribution room
                                                 1 F Power distribution ro°m, boiler accessory room
                                 Fig. 2-3   Layout

-------
     incinerated in a fluid medium at about 800° C.
  b.  Exhaust gas treatment
     Most of the high temperature ash is removed from the exhaust gas by means of
     double cyclones and heat is recovered from the gas with a reduced dust concent-
     ration in  the  air preheater and waste-heat boiler. Fine dust is removed in the
     multi-cyclone and  dry-type electrostatic  precipitator, and the  residual  gas  is
     discharged from the stack into the air.
  c.  Ash treatment
     Ash discharged from  each piece of equipment  in the  exhaust gas treatment
     process is transferred to an ash bunker by the conveyor, moistened, and disposed
     of.

2.1.3   Design  elements
     Design elements of the incineration system are illustrated in Table 2-2.
                              Table 2-2   Design elements
Item
Incineration capacity
Properties of
sludge cake
Kind of sludge cake
Water content
Gross calorific value
Solid composition
c | H |N
Pulverized-coal consumption
Cement clinker
consumption
Hazardous
components
Dust quantity
Sulfur oxides
Nitrogen oxides
Dissolved hexavalent
chromium from ash
Gas temperature at furnace
outlet
Heat loss of incinerated ash
Specification
Sludge cake 100 ton/day (max. 120%/30 min)
Pressure de-watered cake with
inorganic coagulant
(Sludge VTS 40 - 80%)
55 - 75%
1,300 - 2,500 kcal/kgDS
13.5 - 2.9 - 1.8 -
22.6% 4.6% 2.9%
About 570 - 690 kg/h
Sludge cake centrifuged
with high polymer
(Stodge VTS 40 - 80%)
70 - 80%
2,500 - 4,500 kcal/kgDS
20.6 - 3.3 - 2.7 -
41.3% 6.6% 5.3%
About 490 -5 30 kg/h
About 100 kg/h
0.02 g/Nm3 max.
50 ppm max.
80 ppm max. (O, 5%) [45 ppm (O2 12%]
0.3 mg/1 max.
800°C min. 900°C max.
3% max.
2.1.4  Construction cost
     The incineration facilities were built during
Fiscal  1978  to  1980 and  the total sum of the
construction costs amounted  to  ¥2,626 million.
The cost in detail is shown in Table 2-3.
Table 2-3
Items of construction
cost
Item
Civil
Building
Machinery
Electric-
ity
Total
Construction cost
185 Mil Yen
455 Mil Yen
1,292 Mil Yen,
694 Mfl Yen
2,626 Mil Yen
Ratio
7.1%
17.3%
49.2%
26.4%
100%
                                      Note: 1. Year of construction Fiscal 1978 to 1980.
                                           2. Building includes the electricity costs for such as
                                             illumination, ventilation and sanitary equipment.
                                         117

-------
2.2  Characteristics of incineration facilities
     Characteristics of the incineration facilities include the application of pulverized-
coal as a supplementary fuel, the use of cement clinker as a fluid medium, adoption
of the dry-type exhaust  gas treatment,  heat recovery  by the waste-heat boiler etc.

2.2.1  Facilities for pulverized-coal
     The facilities for pulverized-coal are composed of the equipment concerning
storage  and feeding. The flow  sheet of  pulverized-coal is  given in Fig. 2-4, the
constant rate feeder of pulverized-coal in Fig. 2-5, and the structure of the kneader in
Fig. 2-6.
     The ease with which pulverized-coal  can be applied to constant rate feeding and
kneading is a factor directly affecting the stability and uniformity of fluidized bed
temperature.
     The constant rate feeder of pulverized-coal provides a model which is less affect-
ed by the variation of bed thickness in the hopper.
     The kneader is required to perform continuously, uniform mixing and discharge,
and  hence  it provides reverse  blades in  the outlet side and variable speed  biaxial
paddles with a rotation ratio of 2:1.
     Besides which, the facilities for pulverized-coal incorporate safety measures for
inhibiting temperature rise due to solar heating effect  which includes heat shielding
plates on the  upper part of silos for pulverized-coal,  cooling water spray nozzles
around the  perimeter,  heat shielding plates which  cover pulverized coal conveyors,
and heat insulation layers on the outside surface of pulverized-coal feeding hoppers.
In addition, all equipment has static electricity grounding as well as being equipped
with carbon dioxide fire extinguishers for fire prevention.
2.2.2  Sludge incineration furnace
     The structure of the sludge incineration furnace is given in Fig. 2-7 and its speci-
fications in Table 2-4.
 a.  Inhibition of hazardous components
     Hazardous components are SOx, HCC and NOx in the exhaust gas, hexavalent
     chromium in the incinerated ashes, etc. SOx and HC8 are fixed by being absorb-
     ed into the cement  clinker (Principal component is CaO. Activity exceeds 50%)
     applied as the fluidizing medium according to the following equations.
        CaO + SO2 + ViOj  -»•  CaSO4
        CaO + 2HC8  -*  CaCe2+H2O
     The generaztion of NOx and the oxidation of trivalent chromium in the incine-
     rated  ashes to hexavalent chromium are inhibited by a reducing environment
     produced in the furnace  by recycling waste gas or decreasing the air content.
     Malodorous materials  are completely decomposed  by oxidation at exhaust gas
     temperatures of 800 - 900°C.
 b.  Feed and discharge equipment for fluidizing medium
     The furnace provides feed, overflow and underflow equipment for automatically
     controlling  the correct bed height and properties of cement clinker which con-

-------
                                                                                        Discharger with pipe

-------
Fig. 2-5   Structure of pulverized-coal constant rate feeder
                            120

-------
   Fig. 2-6   Structure of kneader (Section)
Table 2-4   Specifications of incineration furnace
Items
Model
Incineration quantity
Furnace bed load
2
01
<**
0
Accessories
Inner diameter of layer
Inner diameter of empty
drum
Incinerator height
Fire brick
Insulating fire brick
Fire castable
Insulating castable
Casing
Perforated plate
Perforated nozzle
Starting burner
Auxiliary burner
Overflow damper
Underflow damper
Other items
Specification
Fhiidized bed furnace
4,720 kg/h (including pulverized coal 553 kg/h)
520kg/m2-h
03,400 mm

-------
                                   Kneaded cake
                                                  O2 sensor
                                                      Exhaust gas
 Secondary air	
Starting burner
                                   Fluidizing medium
                                   (cement clinker)
Auxiliary burner-
     Fludization air —
Under- flow damper
 Overflow damper
                          Fig. 2-7   Structure of incinerator

      stitutes the fluidized bed (Refer to Fig. 2-7).
   c.  Fuel
      Pulverized-coal is used during normal operation as the suplementary fuel, where-
      as kerosene fuel is applied during start up and  if there is a rapid drop of bed
      temperature in normal operation.
      An example of combustion flow chart is shown in Fig. 2-8.

 2.2.3   Equipment for heat recovery
      The high temperature exhaust gas discharged from the fluidized bed  furnace is
 subject to  heat recovery   in the air  preheater  and the waste-heat boiler. The heat
 recovery flow is given in Fig. 2-9.
   a.  Air preheater
      The function of the  air preheater is to heat fluidizing air  up to about 400°C
      by means of a vertical tubular heat exchanger which is low in dust adhesion and
      easy to inspect. To prevent blockage the tube is  relatively large in diameter and
                                        122

-------
Fluidiged
bed
temperature
Auxiliary-
burner tjtl
quantity
                    Temperatu
                    "rise control
Steady-state	
temperature |ncreas<
control   ;  control
                               The status-qu
                               retention

                       Reduction
                       I control
                          i     I       I control         control    _
                                                                                     Reduction
                                                                                     control
                                         Increase
                                         control
                                             Feed stop
                                             control
                Increase
Feed stop  Auxiliary control
         burner
         control
	i' PID continuous control (furnace
—————    | temperature set at 800°C)
                                                           The status-quo
                                                           retention
                                                           control
Pulvenzed-
coal feed
quantity
Feed system
(sludge cake)
Starting bum
nil quanaity
                 10% PC increase
                 only once
                    Feed system   j
                  -stop	u
                             J	L
                                           Hour
 Exhaust 935 880°C
                        Fig. 2-8    An example of combustion flow chart
Steam 3900 kg/h, 16 kg/cm5 G

                   iaOOkg/h
                          Waste-heat
                          boiler
                         \-AJ
                      Blow-down
                                                   |2100kg/h
                  3
                                                           Wet steam
                                        Lower pressun
                                        condenser
                                                                                C~l.
                                     Condense
                                       80°C

Heat exchangerl I Heat exchanger
li i .. i
1
1
i 7
1 1
Heat exchanger!
- S
*
1
1
                                                     Condense
                                                    ftjre water
                                                    Ifead)
                                                                                    I
                                                                                    J90°C

                                                                                    i
                                                                   70°C
Incineration
facilities
(heating)

Incinwatkm
f»cillti» (hot
water supply)
                            Fig. 2-9    Heat recovery flow diagram

       is  equipped with  a guide  sleeve  at its upper end. The structure of the air pre-
       heater is shown in Fig. 2-10.
  b.   Waste-heat boiler
       The .waste-heat bofler is a twin bodie
-------
Fig. 2-10  Structure of air preheater
Fig. 2-11  Structure of waste-heat boiler
       back pressure turbine which drives the induced draft fan and forced draft blower
       in the system and reduces by about 32% the electric power consumption in the
       system. Basides which, the waste steam from the back pressure turbine provides
       a heat source for the plant management buildings for heating, air conditioning
       and hot water supply. The condense is used for replenishing boiler water.
       In  addition, the induced draft fan and forced draft blower are driven  by two
       means, steam and motor, because of the requirement for stability at the start
       and during normal running.

  2.2.4  Exhaust gas treatment
       As the incineration system inhibits SOx and NOx in the incineration process it
  requires  no incidental equipment for alkaliwashing, waste liquid treatment, white
  smoke prevention, etc. Therefore, dust removal is the sole requirement for waste gas
  treatment and hence the dry method of treatment is applied. The dust in the  exhaust
                                      124

-------
 gas is removed by about as much as 65% in the double cyclones, then further reduced
 in the air preheater and waste-heat boiler. About 70% of the residual dust is removed
 in the nuilti-cy clones, followed by a further elimination of about 99.75% or more of
 the residue in the dry type electrostatic precipitator, and the resultant gas is discharg-
 ed from the stack into the air with a dust concentration of 0.02g/Nm^  or less.
      The  double  cyclones, in addition, are arranged just after the furnace outlet to
 reduce the dust load on the air preheater. The dust extracted by the double cyclones
 is at high temperature and great in quantity, and hence a cyclone ash cooler is provid-
 ed as illustrated in Fig. 2-12.
Cooling water
inlet
               I
                                                            Ash inlet
                                                Cooling water /
-------
  Sludge treatment
  control center
  level
Incineration facilitie:
control center level
                              Central processing unit cathode
                              Cathode ray tube
                              Data typewriter
                              Micro-controller
                              Data-way (mam station)
                              Data-way (sub-station)
                              Instrumentation control board
                               nstrumentation board
                              Sequence controller
                              Signal transmission board
                              Local comprehensive board
                              Metal enclosed switchgear
                              Motor control center
                              Local switching board
Incmeratio
(No 1)
Control roo
Incmeratio
i No 1 ) pov
distributor
Marhir
level (1
i facilities
n level
IB-1J

T facilities
ver
room level
le site
oad)
1


-

1CB-11


1 IN



,1


Truck wetgh-bndge
and crane-SQC




£
C~
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SQC-11
**-,
LCB-Ql
i

/t\





STB ]
MC

c
                   Temperature   Control
                                 valve
                              g stgnal
                                                          Transformer     Motor
Electro
magnetic
valve
                                                                                 Digital
                                                                                 signal
Control     Pressure
valve
                                                                                                                         Analog signal
                                              Fig.  2-13     Constitution of control system
                                                                     126

-------
t
	
,t,tr) OO<-
(
,t ,„.•,.„£.
I
	 	 1 | 	 1
twin i rVMriU-il _ I
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bum, r

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Auxiliary
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Feeding system
operation


Fuel
fundamental
feed control




Continuous
blowva ve open


Turbine start
]
	 1






No U 1?

Truck weiqli brnfrR-
Pit y.i;L-
Signal lamp

iiiicrtion control

Furnace outlet (HS df.ift
Ga^q-.ianliiy (temper Control

0 0
1 8
Boilci pressure and -^ *
temperature control




2
it i s

Steedy-state furnace Furnace feed
	 1
temperatufe coniroi system
IAsh system
,
Loww pressure
steam control


Mtiin machinery and ^ols j
in each seqtHMicy Wo» k |
Wviier supply immp
f.« ti electromagnetic vrt!>/<'
Furnace lop tlurgmg darnpcr
Ajl conveyi>*
Nee Irostaiic pnicipitdtoi
Ash damper
Buder wdtef feed pump
Boiler water feod bypais vrflvt1
Builw «3tei lend tram valve
Sliirt blow down valve
IDF inlet damper
PDF
FDR
GR6
. GHB outlet dampar
GHB bypass damper
IDF
MlB
r-DF
GHC.
Sue ting burner
Kp(^sen« pumn
f
Ki i.isene pump
Sludge cake conveyor
Sludge cake hopper feeder
Pulverized -coal conveyor
Pulvenzed-cojl silo discharger
Pulvenzed-coal hopper feeder
Medium hopper feeder
1
Condenser
Fig. 2-14   Start-up process
              127

-------
ro
oo
                                                                                                                                                                                     	Ab  jand< rroceis	*j



                                                                                                                                                                                     •uble Jpve[  1  Feed sybiem slop


                                                                                                                                                                                            Level  2 Combustion j/stem s;cp



                                                                                                                                                                                              \.      Level 3  Drat*, system stop
                                    -F«d,ngstor ^»




                                                     i Fe-Bd.nastop ' nv.pd
                                  Combustion, stop •
                                                     O Draft s.cp '-i
                                  A'ater service stop •
                                 Mih  rfi°'r"er' Sl0p 00T





                                                     O Ash ireatmenr stop f mis




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                                      J          OOj
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dunr,qnribJ$tii



















































F ,d.,.,er,MOP






AUKI' or' Dutn^f stop

Tvni^S'^p

Draft System sto;:



Damper fuHv ciosed


Boi'cr water step

Cont'iuous biov down
,1 .'« CiOSf'1

C^e-nCrtfi injectT'-
twnij -;:(p

Ash irBatmeri s 'sterri stoc:






































































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f)di dr0i' ( fifiUD'






















































Boiler pressu



























e and
1 ^












































































1


























































































































































































































                                                                                                      Fig. 2-15    Shut-down process

-------
                                                                                                                                          [   ^ Mark
                                                                                                                             means o^dinarv • ~ntrol
             To sludge treatment center
    Micro
    -controller
ro
vo
              r
                                                                                                          No. 11  Micro-controller (CTR)      (TI future) No21CTR
                                                                                                                                _               —
    Sequence controller
    Load and sensor
                                                                 Truck priority control
                                   Start command
                                                Furnace number
                                                and pit gate
                                                number
                                                                                                                       storage quantity
                                                                                                                                                     Gate numbei
                                                                                                                                                     instruction
                                                  Gate number instruction
                                                                                                                                                 Signal
                                                                                                                                                 lamp
                                                                                                                                                 control
Truck weigh-bridge
      control
Truck weigh-bridge
guide indication
Signal lamp
control
sludge cake  |
storage quantity
                                                    Guide     Blue/red
                                                    indication   lighting
                                                                                       Existence
                                                                                       detection
                                                                                                                              No. 12-14
                                                                                                                              Sequence controller (SQC)
                                        Truck
                                        weigh-bridge
                                        control board
                                                      Signal lamp (blue, red)

                                                      Car detector (supersonic type)
                                                      Pit gate
                                                      Level gage (supersonic type)
                              Truck weigh-bridge



                                Fig. 2-16   Charge control flow of sludge cake etc.
                                                                         Sludge cake storage pit

                                                                                     o  Movement order of control signal
                                                                                        @ -*• ® ->• Corresponding microcontroller ©  ->  ©
                                                                                                     to truck priority control
                                                                                     o  Movement order of load terminal
                                                                                        (T) -»•  @ -> O  ->• Corresponding furnace (4) -*©-»•

-------
co
o
  Forced
  draft fan
   (PDF) &

>-O-~
      Secondary
      air damper
                                                                                                          Set point of *luid
                                                                                    Set point of oxygen
                                                                                    concentration
                                                                                                          zmg gas quantity
                                                                                    Set point of leaked
                                                                                    air quanaity
                                                                                   Set point of exhaust
                                                                                   gas water content
                                                                                           NOX reduction in
                                                                                           exhaust gas and	,
                                                                                                  Insurance of
                                                                                                  combustion
                                                                                                  air quantity
                                                                                                                quantity control
                                                                                           insurance of
                                                                                           combustion air
                                                                                           quantity
                    Furnace outlet
                    oxygen
                    concentration
                                                                                                                  Induced
                                                                                                                  draft far
                                                                                                                   (IDF)
                                                                                    Fludizing
                                                                                    air quantity
                                                                   Forced
                                                                   draft blower
                                                                   (FOB)
                                                                                               Gas recalculation
                                                                                               blower
                                                                                               (GRB)   A Recirculation
                                                                                                            damper
                               Fluidizmg
                               gas quantity
                                        Recycled
                                       gas quantity
                                                                                                                                                      Micro-controller
                                                                                                                                                      and sequence controller
                                                                                                                                                                 I
Fluidized bed
   furnace
                                                                                                                       Start-up order of fans and blowers
                                                                                                                           IDF-»GRB->FDe-*FDF
                                                                      Fig. 2-17   Air quantity control flow

-------
                 Table 2-5   Outline of micro-controller operation
System
name of control
Outline of control
Main equipment to be
controlled
No. 11 Micro-controller
Acceptance system
Boiler system
< 
-------
                                     Table 3-1  Comparison of fuel consumption and exhaust gas quantity in each incineration process
\. Incinera-
N, Uon
\rirocess
Items \
for \
comparison N.
Sludge calon-
lc value
kcal/kg-DS
c Capacity
jo g t/day
£ £ W»t« con-
S "3 tent of
ggHudgecake*
Excess
airntio
Fuel consump-
tion kg/h
Fuel consumption
pet ton of sludge
cake kg/t
Incineration out-
let exhaust gas
Nm3/h
Gas to deodon-
zation Nm3/h
Counted in fuel
for power consumi
tion kg/h
(Powei for equip-
ment kW)
Flow sheet
Multiple heath furnace
Without
deodonzation
(A)
With
deodonzation
(B)
Fluidized bed
furnace
(C)
Separately dried sludge incineration
Direct drying— fluidized bed furnace
Without
deodorization
(D)
With deodorization
Deodonzation in the
fluidized bed furnace
(E)
Deodorization in the
deodorization furnace
(F)
Indirect drying
— fluidized bed
furnace
(G)
2550 (Net calorific value)
100
79 I VTS 55 1
79 [ Ash 45 '
2.0
117
28
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1 I £. .Central
Ash 20°C
182
44
11840
.DG7080,
IMV47601
18250
.DG7680 ,
'MY 570 '
55
(240)
I Deodar"]
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cake 1 "»em
— -> pic
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85
(370)
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H£
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1580
• DG1470,
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79
(345)
I
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. -A- h^n^_j
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-------
 that an almost equal quantity of fuel to that used for incineration is needed, even
 though heat is recovered by the heat exchangers. The gas quantity to be deodorized,
 although sealing air of the electrostatic precipitator is added on the way, decreases by
 defumidifying to about 3/4 of the exhaust gas quantity at the outlet of the furnace.
     Fludized bed furnace has a high outlet temperature of 800°C, hence fuel con-
 sumption becomes greater. The exhaust gas quantity, although a large amount of fuel
 is used, is somewhat less than that of the multiple hearth furnace due to a lower ex-
 cess-air ratio of  1.3. The fuel consumption,  however, is less than that of the multiple
 hearth furnace with deodorization. Heat recovery is performed by heating the fluid
 air in the heat exchanger.
     There are two  types of incineration methods with separate drying processes,
 which are classified into directly and indirectly heated dryers. Both  types perform
 additional fuel combustion effectively in the process of drying sludge cakes  to their
 spontaneous-burning points. Therefore, the exhaust gas quantity at the furnace outlet
 reduces to about one  half that of the conventional multiple hearth furnace or fluidiz-
 ed bed incinerator. This is  attributed  to low water content  of the sludge  and the
 elimination of exhaust gas resulting from fuel combustion. If  water  were removed
 from the  sludge by evaporation in the fluidized bed furnace, water must have been
 emitted as steam having a temperature of 800°C and this would require a heat quanti-
 ty of over 950 kcal per kg of water. Therefore,  water removal prior to incineration
 has a calorific advantage, along with reduction of exhaust gas quantity.
     The combination of directly heated dryer and fluidized bed furnace is divided
 into  necessary and unnecessary cases of exhaust gas deodorization. Even if deodoriz-
 ing is needed, the required gas quantity  is less than  1/4 that of the multiple hearth
 furnace. There are two  deodorizing methods and these are performed either in the
 fludized bed furnace or in another deodorizing furnace.
     The combustion furnace deodorizing method causes exhaust gas increase by a
 corresponding quantity, thus results in calorific disadvantage and larger  sized furnace.
     When an indirectly  heated dryer is combined with  a fluidized bed furnace, the
 smallest quantity both of exhaust gas and fuel consumption is obtained compared to
 other methods. The  heat recovery of exhaust gas is carried  out  in the waste-heat
 boiler and generated steam  passes to the dryer. This process is more favorable than
that  of the heat exchanger because of  lower exhaust  gas temperature after heat
recovery. The  exhaust gas from the dryer is  defumidified and utilized  as combustion
air for the incinerator together with deodorization. When dry steam from the waste-
heat boiler is  insufficient, additional heating is provided by another boiler.  The ex-
haust gas from the boiler is used for white smoke prevention  regulations.
     In this experiment, after selecting the model of sludge dryer to reduce the water
content of sludge cakes to about their spontaneous-burning point, we  intend to con-
firm  the characteristics in energy saving and  operation control of the separate drying
incineration systems composed of sludge dryer and incinerator.
3.2  Experiment plan
     Experimental facility  has a treatment capacity of 10 .tons/day. Concerning the
                                    133

-------
sort of sludge,  five kinds of sludge cakes from  four sewage treatment plants were
used.
     Also, the dryers are selected by preliminary experiments. The full procedure for
the experiments is given in Table 3-2.

                         Table 3-2  Schedule for experiments
Year
Month
Preliminary
experiment
Main ex-
periment
1980
1981 1982
4 6 8 10 12 2 4 6 8 10 12 2 4 6
i ii iii i i i i i


Design, ~"
manufac-
ture, Experiment
instal-
lation




Design, ma-
nufacture, Experiment
installation

3.3  Preliminary experiments
3.3.1  Outline
     The sludge cakes have a large variation in their properties such as water content,
calorific  value, composition  etc., and hence the  dryer  which can perform stable
operation for any sludge should be selected.
     There are two drying processes, direct and indirect heating methods, as shown in
Fig.  3-1. As the indirect heating method is advantageous, comparative experiments
were carried out on the three indirectly heated models.
     The types and characteristics of the dryers are given in Table 3-3 and experimen-
tal methods are shown in Fig. 3-2.

3.3.2  Results of preliminary experiments
 a.  Properties of sludge cakes
     Analytical results of sludge cakes used in the experiments are given in Table 3-4.
     Net calorific value and water content at spontaneous-burning point are briefly
     divided into two groups on the  basis of Table 3-4.
     (a)  Inorganic coagulant added sludge
         Net calorific value
         Water content at spontaneous-burning point
     (b)  Organic coagulant added sludge
         Net calorific value
         Water content at spontaneous-burning point
 b.  Outline of experimental results
     Experimental data obtained from the three equipment  models and six methods
     are given in Table 3-5 to 3-7, and the summary is illustrated in Table 3-8.
 c.  Discussion of results
     If an indirect heating method is used to  sewage sludge which properties vary
     widely, a low speed disk mixing dryer seems to be suitable. The dryer couid not
     control effectively the water content of dried cakes, and yet the content was
1650kcal/kg-DS
41 -45%

2800 - 3400 kcal/kg-DS
62 - 65%
                                     134

-------
                                                                        Table 3-3    Types of indirect dryer
                                          Structure and characteristics
                                                                                                        Structural figure
               i

               I
               3
               3
                                                                                                  Sludge cake inlet
The steam tubes are concentrically arranged along the whole inside length
of a rotating cylindrical container installed at a slightly inclined angle and
fabricated so as to rotate with the body.
Steam is passed through the tubes and sludge cakes are fed in and dryed by
means of the combing and stirring action of the tubes.
Viscous sludge tends to stick, whereas this type requires less power.
The speed of rotation is 2 - 10 rpm.
                                                                                                                                                                       Drain

                                                                                                                                                               Dryed cake outlet
OJ
A shaft fixed with many stirring paddles rotates at high speed in the center
of a cylindrical container which is equipped with a steam heating jacket.
Steam Is passed into the jacket of the container.
The sludge cakes charged are dispersed by the centrifugal force of the
stirring paddles and dryed by repeated contact with the heating surface.
High efficiency is obtained but unfortunately this type has the drawback
of requiring power. The speed of rotation is  100 - 400 rpm.
                                                                                                        Sludge cake inlet        Steam inlet


                                                                                                                                      •Efiy   Tf  
-------
           (Mdchanic.il diving )
                    Fig. 3-1   Drying process
Mixe
r + Dryer
Grinder
Mixer + Dryer
                                                   Paddle angle 0"
                                              1— Paddle angle 30° feed pucli
                                                     Dry ere
                    Fig. 3-2  Preliminary experimental process
     affected by the variation of operating conditions such as steam pressure, rotat-
     ing speed etc., though correlation could not be measured.
     Therefore, concerning the selection of models, we adopted the low speed disk
     mixing dryer which is able to operate steadily and evaporate quickly from any
     sludge as shown in Table 3-8.

3.4  Outline of main experiments
     The flow  sheet and equipment specifications  of experimental facilities are given
in Fig. 3-3, and their layout is illustrated in Fig. 3-4.
     The experiments are  being performed on the site of Kanazawa Sewage Treat-
ment Plant.
     Sludge cakes in use for the experiments are the same as those used in preliminary
experiments.
     Currently  the experiments are in continuation.
                                       136

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                              Table 3-4    Analytical value of sludge cakes
\Scwage
N^ treatment
— -^_ plant
Items ~~~-^-^^
Treatment
Dewatering machine
t'oagi
Sludge cake


Sort
Jlant Addition
%DS
Water '1,. WB
Combustible
mailer %DS-B *1
_ Raw
5 ^ protein
g,to Raw fat
|t« Raw
0 fiber
Calorific
value
Kcal/kgDS
Cross
"2
Net '3
Water content at
spontaneous-burmnp
point %WB *4

Chubu S.T.P.
Anaerobic digestion
Belt filter
Ca(OH), rc,CI3
55.2 6 9
73.6 - 76 3
35.9
14.3
2.0
6.9
1805
1647
40.7
Soft clayey
material with a
low
fibrous matter
content
Nanbu S.T.P.
Anaerobic digestion
Centrifuge
Polymer
1.2
71.7 -82.0
51.4
19.3
6.8
7.5
3183
2904
62.1
Viscous material
with a high fibrous
matter content.
Totsuka D S.T.P,
Direct dewatering
Pressure filter
Ca(OH), FCjClj
32.8 6.3
58.2- 66.5
31 1
11.4
1.4
16.2
1805
1647
45.2
Light yellow plates
with a thickness of
5— 7mm and a
high fibrous mattei
content.
Direct dewatering
Centrifuge
Polymer
0.8
79.1 -81.1
64 4
26 I
78
133
3695
3371
65.2
Viscous material
with a high fibrous
matter content.
Kanagawa S.T.P.
Direct dewatering
Centrifuge
Poly inei
0.9
77.0 - 78.2
48.5
203
8.4
4.7
3045
2778
61 5
Non-viscous material
containing fibrous
matter.
Noli- *1 Analytical value at 600°C, 2hrs
     •2 Analytical value by JISM.8814
     *3 Calculated value
     *4 Calculated value (fluidizcd bed furnace with an an excess ratio of 1.3 and a furnace outlet gjs temperature of 800°O
        Table 3-5   Experimental data on steam-tube dryer (Heating surface area as 4.8m2)
Conditions
Sludge

Vacuum
tillered
sludge fake
t Digested sludge


Pressure
filtered
(Raw sludge)





('cntrilugcd
sludge cake
( Raw sludge)


Feed
kg/h

60

70


60

70


120


60


70

Steam
pressure
kg/crr?C

8

8


8

S


in


8


8

Dryer's
rotating
speed rpm

g

8


8

8


8


8


8

Water content
%WB
Inlet

75.4

41.5


59.3

31.6


35.5


73.7


36.4

Outlet

56.1

6.4


38 1

2.1


5.0


536


7.5


ation
nte

5.5

5.4


4.3

4.4


8.0


54


4.5


Power of
dryer
kW

Unknown

0.46


0.48

Unknown


Unknown


041


0.44


Feeding process

Direct feed of
sludge cake

Feed back piocess
with grinder and
mixer

Direct feed of
sludge cake

feed back process
with grinder and
mixer

Teed back process
with mixer


Direct feed of
shidge cake

Feed back process
with grinder and
mixer

Drying & sticking
situations
Cakes are cloggin up the inside
from the inlet to the mid-section.
and tubes are buried after pro-
longed operation.
Dried material is in grains of
1-10 mm diameter. No
sticking u found.
Dried material is a mixture of
cotton dust fibrous matter and
flat material having traces ot the
original form.
No sticking is found
Dried material is a mixture of
grains with a diameter of 2 -
10 mm and fibrous matter.
No sticking is found.
Repeated drying gradually
increases gram diameter of
dried material.
No sticking is found.
Dried material is in grains of
10 - 40 mm diameter and it
clogs between tubes and between

Dried material is in grains of
1 - 5 mm diameter.
No sticking is found.
                                                   137

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Table 3-6   Experimental data on high speed paddle mixing dryer (heating surface area 4.0 m2)


Sludge

Vacuum filtered
sludge cake
(Digested sludge)
Ditto

Ditto

Feed

150

150

150

Steam
pressure
kg/cm2 G
8

8

8

Diyer's
rotating
speed rpm
150

300

400

Water content

Inlet

75.0

75.0

75.0

Outlet

589

54.9

536


Evaporation
kg-H2O/mJh

14.7

16.7

17.3



dryer
kW

2.22

2.76-
3.24





Drying and sticking situation

Relatively uniform grams of 5 — 10 mm
Considerable sticking is tound onto the
rotation shaft.
Relatively uniform grains of 5 - 10 mm.
No sticking is found.
The same as above.
But re-start-up was impossible after
sampling
  Table 3-7   Experimental data on low speed disk mixing dryer (heating surface area 4.8 m2)
Conditions
Sludge
Vacuum filtered
sludge cake
(Digested sludge)
Pressure filtered
sludge cake
(Raw sludge)
Centrifuged
sludge cake
(Digested sludge)
Feed
kg/h
180
180
240
240
240
240
Steam
pressure
kg/cm'G
7
7
7
7
7
7
Dryer's
rotating
speed rpm
31
31
20
39
39
31
Water content
%WB
Inlet
75.4
76 1
66.5
66.5
79.6
74.5
Outlet
51 3
44.8
450
529
53 2
51 1
Evaporation
rate
kg-H20/m'h
18.6
21.3
19.5
144
282
23.9
Power of
dryer
kW
1.21
1.32-
1.38
1.37-
1 49
1.62-
1.76
1.22
1.37
Weir
height
mm
140
290
140
140
140
140
Drying and sticking situations
Dried material is in grains ol 1 - 5 mm
No sticking is found
Dried material is in powder form of
01-1 mm.
No sticking is found
Dried material is in grains on blocks of
30 - 50 mm.
No sticking is found
                   Table 3-8  Summary of preliminary experiments
N^""--— ^^_^ Operation
N^ — ^^^^ condition
D^\p^\
Steam
tube
heating
type
High speed
paddle
mixing
type
Low speed
disk
Mixing type
Direct feed
Feed
back
process
Direct
Feed
Mixer
Grinder
Mixer
Paddle
angle
0°C
Paddle
angle
30*C
Direct feed
Sticking
Unable to
operate
No
No
Yes
No
No
Stability


Poor
Dried cake grains
gradually expand.
Good
Poor
Cake sticking at iruet
causes over-drying at
outlet (25% or leu)
Poor
Operation is stabilized
with a narrow range at
300 rpm rotating speed
and 150 kg/h feed rate.
Good
Operation


Poor
Many accessories are
required.
Poor
Many accessories are
required
Poor
Variation of motor
load sometimes causes
overload.
Good
Poor when feed rate
is varied.
Good
Controllability of dried
cake water content


Although controllable by
changing the dried material
feed back ratio, it is hard
to operate practically
Although controllable by
changing the dried material
feed back ratio, it is hard
to operate practically.
	


Correlation cannot be
obtained (at 20-40rpm
ratating speed and 2-7
kg/cm'G steam pressure)
Evaporation
rate
kg-HjO/m^h


	
4-6


14 17

20-30
                                        138

-------
                                                 Final effluent from S.T.P
                                                                                               Kerosene     Service water
CO
to
                                                                                                                                                      Dram
Equipment No.
Equipment name
Model
Main dimensions
Volume
Number
I
Cake hopper
Cubical type
2353W/3000*
x 21501-
I2ms
1
2
Dryer
Low speed disk
mixing type
670* x 2850L
500 kg/h
3
Condenser
3 stage spraying
direct cooling type
*762x6000H
12m3/min at
100°C
1 1
i 	 i 	
Incinerator iFluidizing air blower
Fluidized bed Multiple stage
furnace j turbo-blower
1
*1 100/^1 600
x9200H
Sludge cake
lOt/day
1
0
125
10m'/mu\ \
3500 mmAq
1
6
Cyclone
Refractor}
castable
lining
0
980 x 4300«
40m3 /min at
800°C
1
7 8
Wast-heat boiler
Water tube tvpe
Heating surface
area 29m1
Induced draft fan
Plate type
*300
380 kg/h x 10 kg/ 30m3 /min x450
cmaG j mmAq
' i '
9
Scrubber
Upper pait.
Spray type
Lower part.
Packed tower

750xl5000H'

1
10
Boiler
Single pass
type
Heating surface
area 517m1
350 kg/h x 10 kg/
cm'G
1
                                  Fig. 3-3   Flow sheet and equipment specifications on separately dried sludge incineration experiments

-------
                               Condenser pump i
                  Drainage pump

                     Drain tank
Condenser fi^ Coke dischar_
               from dryer
                                   Induced draft fan of dryer
                Scrubber
              recycle pump      adiusting device
Fig. 3-4    Lay-out of equipment on separately dried sludge incineration experiments

-------
Closing Remarks
     As mentioned above, a couple of new aspects on the incineration of sludge cakes
were introduced.
     The need or situation demanding the incineration in the sludge treatment pro-
cess depends upon the method for final disposal.
     Accordingly, there is no need  for incineration when  the sludge cakes may be
subsequently  utilised as a fertilizer etc..Whereas it will be a valuable technology when
land disposal can be continued for a long period in the area limited.
     Yokohama City is obliged to take the latter case.
     Henceforth we want to make every effort also  for the development of stable
and economical incineration technology.
     Finally, the author would like to  acknowledge the considerable assistance given
in the preparation of this report by M. Noguchi, equipment manager, S. Yamaguchi,
facilities sub-senior chief, and other member of facilities and maintenance  sections.
                                      141

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-------
                                            Eighth US/JAPAN Conference
                                                    on
                                            Sewage Treatment Technology
CURRENT STATUS OF AUTOMATIC MONITORING
                              OF
   WATER QUALITY IN SEWAGE TREATMENT
                          October 13-14, 1981
                          Cincinnati, Ohio USA
            The work described in this paper was not funded by the
            U.S. Environmental Protection Agency.  The contents do
            not necessarily reflect the views of the Agency and no
            official endorsement should be inferred.
                       Ken Murakami
                       Water Quality Section,
                       Water Quality Control Division,
                       Public Works Research Institute,
                       Ministry of Construction

                               143

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1.    INTRODUCTION

          The necessity  for  automatic measurement of water quality  in sewerage
     system has  been  strongly  recognized, particularly  treatment process
     control and monitoring  of hazardous substances in  sewage.  Both the users
     and manufactures are  engaged  actively  in  technological development in
     this field.  This paper summarizes the recent progress in automatic water
     quality measurement in  sewage treatment systems.   As to  instruments for
     monitoring  hazardous  substances in sewage, an automatic  lead monitor and
     an automatic total-cynide monitor have been newly  developed.   Also
     developed is automatic  samplers to take sewage samples in case abnormal
     pH-changes  are detected.   A project is in progress to evaluate the
     the reliability  and performance of automatic water quality measuring
     instruments when they are operated under  actual conditions.  As a first
     step,  an investigation  to evaluate the performance of pH sensors under
     field  conditions has  started,  including establishment of methodology to
     evaluate these instruments.
         Along  with  the progress  in construction of sewerage systems, the
     percentage  of the loading discharged into public water bodies  through
     sewage treatment plants is gradually increasing.
         For this reason, the control of load discharged from sewage treat-
     ment plants in order  to preserve the water quality of public water bodies
     is gaining  greater  and  greater importance.  In certain regions, today,
     automatic measurement and recording of the organic loading discharged
     from sewage treatment plants  is being  made compulsory, as it is for
     other  sources of pollution and polluters.
         To implement similar restrictions on phosphorus also in the future,
     a  total phosphorus  automatic  analyzer  is  now being developed.
                                      144

-------
2.    AUTOMATIC MONITORING INSTRUMENTS  FOR HAZARDOUS SUBSTANCES IN SEWAGE

          Control  of hazardous  substances,  especially heavy metals, contained
     in sewage is  one the most  important  task  in  the operation and maintenance
     of sewage treatment plants.   Sewerage  authorities have assigned  a  large
     number of personnel to  monitor water quality of industrial waltewater
     dischanged into the sewerage  system  to enforce pre-treatment standards.
     At present, water quality  monitoring of this kind is being done  manually,
     but when automatic monitoring equipment becomes available in the future,
     still better  monitoring will  be accomplished.  The Ministry of Con-
     struction, in the past  several years,  has been funding a contract  re-
     search program to develop  automatic  water quality monitoring equipments.
          In this  project, automatic monitoring equipment for total cynide,
     chromium, cadmium, and  copper have been developed.  Summaries of
     work were presented at  previous meetings.
          In this  section, recent  activities for  developing a lead monitor,
     improving the total cynide monitor and developemnt of automatic  samplers
     operated by signals from a pH sensor are  outlined.

 2.1  Development  of Lead Automatic Monitor

           The lead automatic monitor  being developed utilizes an ion-
      selective electrode.  Major  problems  encountered in its developemnt
      are:  (1)  ordinary sewage contains  copper,  iron and organic substances
      in concentrations which interfere with the  measurement  of lead  by an
      ion-selective electrode,  (2) lead contained in sewage is mostly in the
      particulate  form, and  it  has to  be  dissolved before measurement.
      Therefore, various experiments were conducted to determine the  pre-
      treatment method, and  finally a  measuring instrument was devised  based
      on the following principle.
           Fig. 1  is block diagram of  the automatic lead monitor.
                                      145

-------
Drain
                      Tap water
                            Tap water drain
                                                              HCl-NH4Cl-CK3COONHu
                                               Reaction vessel
                                                 Heater
                                Drain  Oil bath
     ISA
 Distrilled water
            Fig. 1   Block  diagram  of  the automatic Pb monitor
                                     146

-------
      A 10 m& mixed solution of 2N hydrochloric acid, 10% ammonium
chloride and 0.1 M ammonium acetate was added to a 200 m£ sample, which
was then heated to dissolve and convert lead into chloro-lead complex
ions.  The ammonium acetate is added to dissolve lead sulfate.
The sample is then filtered to eliminate suspended solids and then
introduced into a column with anion exchange resin.  The column is of
6 mm ID, 65 cm long and made of PVC, while Dowex 1-X8 (type CL)  of 20
to 50 mexh is used as the anion exchange resin.  By this operation, the
lead is adsorbed as chloro-lead complex ions onto the exchange resin.
The anion exchange resin is then cleansed with elute to separate, as
much as possible, the interfering substances that have been adsorbed
onto the anion exchange resin.  The elute is a 10 time diluted solution
of 1M ethylenediamine, 10% ammonium chloride, and 2N hydrochloric acid
mixed solution.  The ethylenediamine is added to form chealate complex
with copper and desorb them into the elute.
     After this cleaning operation, distilled water is run into the
column for 40 minutes at a flow rate (empty bed)  of about 3.5 cm/min
to desorb lead from the exchange resin.  The desorption solution, after
addition of a buffer solution, is transferred to a cell for measuring
lead with an ion selective electrode.  The buffer solution is a mixed
solution of 1M ammonium acetate, 10% ammonium chloride, 0.2M sodium
citrate, 1M sodium thiosulfate, and 1M potassium nitrate, whose pH value
is adjusted to pH6 using acetic acid.  It is added to the sample at
the ratio of 1 :  10.
     The purpose "of adding this solution is  to adjust pH value,  to
adjust ionic strength, and eliminate part of the interferences.   After
taking measurements, the anion exchange resin column is cleansed with
distilled water for about 80 minutes.  The measurement cycle is once
every 2 hours.
     To examine the mechanical reliability and precision of measurement
under the actual operating condition, the device was transported to a
sewage treatment plant and was continuously operated for a period of
about 1 month.  The test showed that, even with the complicated pre-
treatment mentioned above, interference probably due to certain types
of organic substances still remained.
                               147

-------
Although certain correction can be made by data processing,  improvement
of electrodes, etc. are necessary. Fig. 2 shows an example of the
measurement by the instrument.  Here, sample A, B, and C are those
prepared by adding lead to a raw sewage sample at concentrations of
1.0, 1.5, and 2.0 mg/£ ,  respectively.
                Sample A (Sewage with 1.0 rag Pb/1 addition)
                Sample B (Sample A + 0.5 mg Pb/1)
                Sample C (Sample A + 1.0 mg Pb/1)
      Fig.  2  Example of recording of the automatic Pb monitor
                   - the known increment method -
                                148

-------
     As seen in the figure,  the base line fluctuates considerably and tailing
     of the record after reaching its peak is significant.   This tailing is
     considered to be due to interferences.
          By integrating the hatched areas in the diagram,  the lead con-
     centrations in samples  A,  B, and C are found to be 0.98,  1.42, and
     2.14 mg/& , respectively,  that is fairly close to the  added concentra-
     tions .
          In this way, by means of data processing, the effect of inter-
     ferences can be substantially corrected.  However, improvement of elect-
     rode and/or smaple pre-treatment is considered essential.  Work on
     developemnt of a reference(electrode, which may compensate the effect
     of organic interferences,  is being advanced.
          Continuous operation revealed almost no mechanical troubles, but
     confirmed that atmospheric temperature variations have significant
     effect on the measurements,  that is, temperature control  or temperature
     compensation is necessary.

2.2  Improvement of Automatic Total Cynide Monitor

          As presented at the 5th and 6th conferences, automatic total cynide
     monitors, in which the  measurements are taken with an  ion selective
     electrode after distillation, were developed and have  already been put
     into service in a few plants.
          Since the distillation step makes the monitor mechanically com-
     plicated, however, other methods especially that using ultraviolet rays
     (UV)  for decomposing complex cynide is being studied.   In this method,
     UV light is irradiated  on the sample under acidic condition, in order
     to analyze the complex  cynide.   Free cynide is transferred into an
     alkaline solution through a  gas permeable membrane, and finally
     measured by  a cynide electrode.
          Fig. 3 is a block  diagram of a prototype model of the monitor.
                                     149

-------
      Sample  O	=-
EDTA solution


Acetic
acid solution
                                            Valve
    Tap water O	T~
                           Valve
                                                Valve
                          Cyanide separation tube
NaOH solution Q	—^—
                                         Cyanide electrode
                                                                      UV irradia-
                                                                      tion tube
                                                                         O Drain
            Fig.3  Block diagram of the automatic  T-CN monitor
                                                                         O Drain
                                       150

-------
     This monitor is of the continuous operating type,  in which 5M
acetic acid (1 mH/min)  and 0.05M/EDTA solution (1 m /sec)  is added to
the sewage sample (10 m /min),  then UV light from a SOW low voltage
mercury lamp is irradiated onto it to  convert complex cynides into
free cynide.
     EDTA solution is added to prevent free cynides from reacting again
with metals.  Acetic acid is used instead of mineral acid because
mineral acids may cause precipitation of EDTA.
     Next, the sample is transferred to a dual tube as shown in Fig. 4.
          Cyanide electrode ——

                     Sample drain
          Gas permeable membrane
      Sodium hydroxide  soltuion
                                            §
                                            5
                                                     Sample
             Fig.   Complex cyanide decomposition and
                   free cyanide separation portion of
                   the T-CN monitor
                                 151

-------
          The inner  tube  of  the  dual  tube  is made of  a material which  is
     permeable to  gas  (like,  teflon).   Free cynide  is transferred  into the
     0.2N sodium hydroxide solution which  is flowing  through  the inner tube.
     When the sample contains sulfides,  hydrogen sulfide  is formed and also
     transferred into  the sodium hydroxide solution.  To  eliminate this, the
     sample is passed  through a  column  filled with  particulate lead peroxide
     before being  transferred to the  ion electrode  for cynide measurement.
          By controlling  the flow rates  of sample and sodium  hydroxide, it is
     possible to concentrate cynides  to a  certain degree.
          In June  1981, a prototype monitor was installed and placed in
     operation at  a  pumping  station.  Many plating  industries are  located in
     the drainage  area of the pumping station.
          One of the problems revealed  by  the field test  js the interferences
     probably caused by organic  substances. When UV  light is irradiated on
     the sample under  acidic condition,  the organic substances with high
     molecular weight  are decomposed  into  those with  low  molecular weight,
     some of which pass through  the membrane and interfere with the cynide
     measurement.  The degree of interference when  teflon is  used  as the
     membrane, is  about 0.05 to  0.1 mg/£ as cyanide.   This interference can
     be reduced to about  1/3 by  passing the sample  through an activated carbon
     column before taking the measurement  with a cynide electrode.  However,
     since it is desirable to set the detection limit at  about 0.01 mg/£,
     the material  of gas  permeable membrane,  capacity of  mercury  lamp, and
     other factors are being re-investigated.
          This type  of total cynide monitor requires  much less maintenance
     than the previous ones, and is  considered  to be  put  into practical use
     more widely.

2.3  Development of  Automatic Sampler Actuated by pH-meter

          An automatic sampler,  possessing the  function to detect abnormal
     variations in water  quality and begin sampling,  will be  a  very  effective
     tool in improving the  industrial wastewater monitoring system.   At
     present, the  most suitable detector for  this  purpose would be a pH
     sensor, considering  that it can be used  inside the sewer.   Therefore,
     automatic samplers operated and controlled by  the signals  from pH
     sensors have  been developed and undergone field tests.

                                    152

-------
     Three prototype models of the samples were manufactured:   2
portable and 1 stationary type.

a.  Portable type automatic samplers

         The portable type automatic samplers are designed to be placed
    in manholes.   Their major specifications are as follows.
    (1)   Shape
    (2)   Power source
    (3)   Sample volume
:   Shaped to be fitted in standard manholes

:   Battery (operates  for a week without re-
   charging)

:   500 m£, 12 times
    (4)   Mode of smapling:   Sampling with signal from pH sensor or
                            periodic sampling,  selectable

    (5)   Suction head .   :   5 m or more
    (6)   pH sensor
   Accuracy of less  than ±0.1 pH with clean
   water,  and equipped with electrode cleaning
   attachment
    (7)   pH recording    :   Analog or digital.
                            If digital,  the recording shall be done
                            once every hour during normal condition, and
                            once every 10 minutes if the pH deviates
                            outside the set range.  Sampled time also
                            shall be recorded.
         The success of this type of automatic  sampler depends largely
    on the availability of  reliable pH sensors.   The pH sensors used
    for these models are shown in Fig. 5 and Fig. 6, respectively.
                                 153

-------

fr
I
H
r n

k
-n
s
51
j


7
/
/
/
/
/
/
/
/
^
--
1
s: —
r-4-^
Ji,-.
T|

niWr
x'
..
^ 	 Reference electrode and thermister





Fig. 5  pH sensor (Type I)  for the automatic sampler
                         154

-------
  Glass  electrode
Rotor
Thermister
   Magnet
                                             Reference electrode
 Fig. 6  pH sensor  (Type II) for the automatic sampler
                             155

-------
     The Type I sensor shown in Fig. 5 has a built-in pre-amplifier
and power source, which reduce noise caused by outside disturbances.
The glass electrode is mechanically cleaned by a brush which is
actuated by a timer.  The Type II sensor shown in Fig. 6 has an all
solid-state glass electrode whose surface is cleaned by a rotor
driven by magnetic stirrer.  One model uses a vacuum pump to take
samples and has an analog recorder for pH; while the other takes
samples using a tube pump and records pH on a digital printer.
     The samplers were trial-run in the field for 1 year to check
their reliability and to make necessary inprovements.  The precision
of the pH sensors of both types were found quite satisfactory.
After continuous maintenance free operation for one week, the
maximum difference in the measurement with pH standard solution was
found to be 0.3 pH.
     However, dpending on the installation site, large sized
floating substances sometimes became entangled on the electrode.
The shape of the electrode as well as its holder had to be made as
smooth as possible.
     Concerning the dimension of the sampler, its maximum O.D.  was
530 mm so that it could be fitted in standard manholes of 600 mm I.D.
However, in many cases, steps in the manholes reduced the available
space.  Therefore, the O.D. of the commercial model sampler is
recommended to be 450 mm maximum.  Also, since the battery and the
sampled water made the monitor heavy, it became necessary to make
it a lighter one.  The target weight was set to be 30 kg.  After
making these improvements, commercial products have been marketed
from this year.

b.  Stationary type automatic sampler

         This type of automatic sampler operated and controlled by
    a signal from a pH sensor was designed to be permanently
    installed at the inlet sewer or grit chamber of a sewage treat-
    ment plant as well as at the grit chamber of a pumping station.
                             156

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     Since commercial power supply is available at these instal-
lation sites, a refrigerator to preserve the samples was
designed to be built into the sampler, and also where necessary,
output for telemetering signals to indicate pH measurements and
sampling was provided. 24 sampling bottles of 500 m£ were pro-
vided and the sample size was made selectable, between 1 bottle
and 4 bottles.  The pH sensor used is almost the same as Type I
shown in Fig. 5, the difference being that the glass electrode
is cleaned with ultrasonic waves.
     Field tests were conducted for more than 6 months by instal-
ling the automatic samplers at the grit chamber of a municipal
sewage treatment plant as well as at a grit chamber of a sewer
system into which large quantities of tannery wastewater flow.
     At the former site, the flow velocity was about 2 to 3 m
per second and large size floating substances became entangled
severely.  The error of measurements when the electrode was
covered by these substances reached as much as 1 pH.  However,
the measurements could be easily restored to normal through
removal of the large size trash that entangled the electrode.
The growth of slime on the electrode was very slight due to
the rapid flow.  As in the portable type sampler, it is
important to shape the electorode in such a way that large size
floating substances do not become entangled on it.  The effect
of cleaning the electrode with ultrasonic waves was not clear
because only a little slime adhered during the period without
cleaning.
     The field test at the grit chamber into which tannery waste-
water flowed was conducted under a severe condition.  Sometimes
a thick scum formed on the surface of the grit chamber because
the capacity of the chamber was too large for the actual flow.
This gave rise to several troubles, namely, the sampling tube
tended to get clogged, fats and oils adhered to the pH elect-
rode, and so on.  Therefore, the field test is, still being
continued to make improvements in the sampler.
                            157

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3.    EVALUATION OF THE PERFORMANCE  OF  pH  SENSOR  - EVALUATION OF  DETECTORS FOR
     AUTOMATIC PROCESS CONTROL

          Avaiability of  suitable automatic  water quality  analyzers with
     enough reliability and precision  is  an  essential  factor in  automatic
     treatment process control.  Whereas,  adequate  information regarding
     reliability and  performance under the field conditions are  not always
     necessarily available.   The data  provided by manufacturers  usually refers
     to  results with  clean  water, and  rarely refers to the actual  field
     conditions.
          For  this reason,  the Ministry of Construction began investigating
     the reliability  and  performance of these instruments  when used under
     practical field  conditions.
          Beginning this  year, a pH meter was selected as  the first object of
     investigation.   The  investigation includes  establishment of the methodo-
     logy to evaluate these detectors.
          Following is the  current  test protocol for the pH sensor evaluation.

     (1)   Participating manufacturers  shall  supply  2 units of their products,
          respectively.

     (2)   All  instruments shall be  installed under  identical conditions.  And
          the  installation  shall be done  by  the  manufacturers, themselves.

     (3)   Out  of the  2 units,  one shall be operated continuously without any
          maintenance work  until its measurement error exceeds a predetermined
          level (Test I).

     (4)   The  other unit  shall be operated during the  test period  with
          standard maintenance works,  that is, cleaning, calibrating and so
          forth at periodic intervals  (Test  II).

     (5)   Total period of the experiment  shall  be  longer than 2  times the
          period to run Test I,  or  3  months.

     (6)   Manual analysis shall be  done at least once  everyday.

     (7)   At the end  of Test I, pH  standard  solution shall be measured to
          determine the measurement error.
                                     158

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 (8)   Prior  to  each  calibration  operation  in Test  II, pH  standard  solution
      shall  be  measured  to  determine  the measurement error.

 (9)   The  user  or  a  third party  shall perform  the  manual  analysis  and
      regular maintenance work;  and repairs, if any, shall be entrusted  to
      the  manufacturer.

(LO)   The  tests shall be conducted at least 2  places, one under  favourable
      conditions for the measurement  and the other under  adverse con-
      ditions .

(11)   Using  data obtained from the experiment, such as zero drift, span
      drift, difference  of  measurement  from manual measurement,  change in
      response,  executed maintenance  work, and so  forth,  the relationship
      between accuracy and  maintenance, or frequency of maintenance  to
      obtain data  with a certain level  accuracy shall be  examined.

      Experiments  to evaluate the performance  of pH meters are scheduled
 for September  1981  at a municipal sewage treatment plant with the
 participation  of  4  different manufacturers.   The  initial series of
 experiments shall be conducted  at a  grit chamber  for dry weather  flow,
 and the subsequent  ones are scheduled  in a primary settling tank or
 aeration  tank.  In  the  service  area  of this treatment plant, numerous
 Chinese restaurants are located, disposing off fats and  oils which  render
 difficult conditions for automatic measurement.
      The  cleansing  methods employed  in the 4  different versions of
 instruments include one with air bubbles, one with water jet, and two
 with  ultrasonic waves.
                                   159

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4.   AUTOMATIC MONITOR FOR SEWAGE TREATMENT PLANT EFFLUENT

 4.1  INSTALLED STATUS OF AUTOMATIC  MONITORS FOR ORGANIC  SUBSTANCE

           In conspicuously developed regions,  effluent standards which
      regulate only concentrations are not  always adequate to  curb  the  in-
      creasing water pollution;  so in 1979,  the Water  Pollution Control Act
      was amended to implement a total loading  regulation system.   The  regions
      where this Act is applied are  currently the Tokyo Bay, Ise  Bay, and
      Seto Inland Sea basins;  and the pollutant covered by the system is
      limited to COD load (manganese method).  By this act,  the specified
      sources of pollution which discharge  more than 400  cubic meters of waste-
      water were made obliged  to install  automatic monitors  giving  data that
      are highly correlated with manually analyzed COD, and  to make continuous
      recording of the load.  The designated instruments  for this purpose are
      the UV photometer,  COD meter,  TOC meter,  and TOD meter.
           The sewage treatment plants which were subject to the  above
      obligations numbered 67  around the  Tokyo  Bay region,  48  around the Ise
      Bay region, and 124 around the Seto Inland Sea region, that is a  total
      of 239 sewage treatment  plants.  And  the  instruments installed are 229
      UV photometers in 204 sewage treatment plants, 32 COD  meters  in 32
      plants, and 5 TOC meters in 5  plants.   Plants having multiple drainage
      outlets are obliged to install such instrument at each outlet.
           Of the total installed instruments,  UV meters  account  for the
      largest part.  Since the UV photometer requires  less maintenance  and
      is rather inexpensive as compared to  other instruments,  its usage is
      recognized so far as its data  have  good correlation with the  manually
      analyzed COD.
           Generally speaking  organic substances do not have strong absorption
      characteristics against  the UV light  of 253 mm wavelength,  which  is used
      in the measurement, but  sewage which  has  undergone  biological treatment
      contains substantial amounts of refractory organic  substances which absorb
      UV light with a wavelength of  that  vicinity.  Therefore, a  relatively
      favourable relationship  between UV  absorption and COD seems likely to be
      attained.
                                    160

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          However, if the effluent is colored due to industrial  wastewater
     and so forth, the UV photometer may not give an appropriate index.   In
     this case,  a COD meter or some other instrument is used.
          The total number of pollutors which are obliged to take automatic
     measurements under the total loading regulation system is about 4000,
     out of which about 80% employ UV photometers.   The enforcement of this
     type of obligatory automatic measurements is considered to  be very
     effective.

4.2  DEVELOPMENT OF AUTOMATIC TOTAL PHOSPHORUS MONITOR

          The total loading regulation system, as mentioned earlier,  is
     enforced in limited areas with a limited parameter.   However,  there  are
     several stagnant water bodies,  like,  lakes,  etc.,  whose water quality is
     gradually deteriorating.  So,  in the future, not only implementation of
     more stringent effluent, concentration standards,  but expansion of the
     total loading regulation system is expected.  Especially concerning
     nutrients,  national environmental standards  and effluent standards are
     not yet established,  but the control of eutrophication of stagnant water
     bodies is coming up as one of the most important topics in  water pollu-
     tion control policy.   In the near future national  standards are likely
     to be' established.
          Removal of nutrients,  especially phosphorus removal in sewage
     treatment is keenly awaited.   Although technological and economic pro-
     blems still remain  unresolved,  a couple of treatment plants,  which dis-
     charge their effluents into lakes,  already have or have a plan to
     construct phosphorus  removal facilities.   Under these circumstances,
     it can be expected  that in the future automatic measurement of total
     phosphorus  in sewage  will be on schedule.  Therefore,  technological
     research to develop an instrument for this purpose has begun.
          The most important part in analyzing the  total  phosphorus is the
     decomposition of organic phosphorus into orthophosphate.  Therefore,
     automatic monitoring  of phosphorus is being  studied  placing emphasis on
     decomposition of organic phosphorus.   The following  three decomposition
     methods  are being studied:

     (1)   Decomposition  by adding potassium persulfate  and sulfuric acid  to
          the sample,  and  heating the solution.

                                     161

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(2)  Decomposition by UV irradiation

(3)  Decomposition by electrolysis in the presence of sodium chloride

     Method 1 is used in manual analysis which will be the official
analytical method for the expected water quality standards, and a couple
of manufacturers have already  manufactured prototype models of this
instrument based on this method.  In Method 2, it is already known that
complete decomposition with UV irradiation only is impossible,  so that
addition of oxidizing agents, heating, and other means are being
examined.  And, as to Method 3, the decomposition of organic phosphorus
is considered to be done by chlorine and oxygen which is generated by
electrolysis.  This method is reported to be effective in decomposing
the organic phosphorus contained in sea water.
     The phosphorus in secondary effluents exists mostly as dissolved
ortho-phosphate.  Taking this into account, investigation is being
continued to establish the most appropriate decomposition method for the
automatic analyzer, and production of orototvoe models, field tests and
assessment are scheduled for 1982.
                               162

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                                          Eighth US/JAPAN Conference
                                                 on
                                          Sewage Treatment Technology
                 PI LOT PLANT STUDY
                           FOR
TREATMENT OF COMBINED FISH-PROCESSING
                           AND
                  DOMESTIC WASTE
                            IN
                  MAKURAZAKI CITY
                        October 13-14, 1981

                        Cincinnati, Ohio USA
           The work described in this paper was not funded by the
           U.S. Environmental Protection Agency. The contents do
           not necessarily reflect the views of the Agency and no
           official endorsement should be inferred.
                Kazuhiro Tanaka

                Section Chief,

                Research and Technology Development Division,

                Japan Sewage Works Agency


                              163

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1.    INTRODUCTION

          Makurazaki city is situated in  southern Kyushu and as a port has
     performed important duty as a southern ocean fishery base, especially
     for the landing of bonito and mackerel.
          The city has a great number of  medium and small size factories
     manufacturing dried bonito, the  flakes of which are a popular seasoning
     in Japan.  The factories are scattered over about 130 locations in the
     downtown area.  As  the  wastewater discharged from those factories in-
     creased, the water pollution in  small rivers, drains and the port sig-
     nificantly worsened.  Therefore  Makurazaki city planned to receive these
     fish processing wastes into its  municipal wastewater treatment plant to
     improve water pollution in public water bodies.
          Fish processing wastewater  is high in BOD and Nitrogen compared
     with domestic wastewater, and fluctuates hourly both in quality and
     quantity.  Accordingly,  pilot plant  experiments were conducted to
     determine the design and operational conditions of activated sludge
     process to obtain the effluent BOD of 20 mg/& or less.
                                   164

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2.    INVESTIGATION OF WASTEWATER

 2.1  Fish Processing Waste

           Investigation was made of the quantity and quality of the waste-
      water from 4 factories selected according to the size of each factory.
      The manufacturing process of dried bonito is shown in Fig. 1.
           As shown in Fig. 1, the main processes, in which wastewater is dis-
      charged from the bonito drying factories are; defrosting, cutting and
      boiling.  These factories run during the daytime only.  As the con-
      crete floors and instruments are cleaned at the end of operations in
      each factory, the wastewater from the cleaning work is also discharged
      from these factories.  As for the wastewater from boiling process, only
      the overflow is discharged during operation, and the concentrated solu-
      tion remaining in caldrons is usually recovered and used as the material
      for manufacturing seasonings.  However, the comparatively dilute solu-
      tion remaining in the caldrons is not recovered and is discharged on
      weekend.
           The characteristics of the three types of processing wastewaters
      shown in Fig.  1 are as follows:

           Wastewater from defrosting process;  At the early stage of dis-
              charge, the wastewater temperature was especially low at 3 -
              4°C.  The BOD gradually increased from 350 mg/H and finally
              reached about 3000 mg/i  during discharge.  Its quantity was
              about 53% of the total wastewater.

           Wastewater from cutting process;   The suspended solids  in this
              wastewater was around 1000 mg/S, and a large amount of bloody
              water was included.   The BOD was 2000 - 5000 mg/£.  Its
              quantity was 43% of the total wastewater.

           Wastewater from boilding process;   The suspended solids in this
              wastewater was around 2000 mg/fc,  the BOD was 1000 -  5000 mg/£,
              and the normal hexane extract substance was 500 mg/£.
              Compared with the wastewater from other processes, the con-
              centration of this wastewater was highest,  but its quantity
              was only 4% of the total wastewater.

                                      165

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Fresh fish

Frozen fish I •

Water supply
1
Water supply Water supply (for cooling the boiled water)
1
Defrosting I * "1 Cutting I • I Boiling |-"p| Boningr*"| Shaping!— —I Drying —I shipping
                    1               I
Discharge       Discharge       Discharge
Remaining in  the caldron is recovered
                 Fig. 1   Dried bonito manufacturing process
                          and water supply & discharge system

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           Table 1  Average wastewater quality in each process

^~~"---^_^^ Process
Factory""^--^^^
Factory A
Factory B
Factory C
Factory D
Average
BOD (mg/£)
Defrost-
ing
806
731
578
392
623
Cutting
3,360
2,370
1,770
4,010
2,270
Boiling
7,110
7,170
6,380
13,940
8,190
Washing
floor
-
1,420
4,350
4,550
-
Average
1,970
1,610
1,570
1,760
1,720
SS
(mg/S, )
Average
714
293
776
434
542
CODMn
(mg/£)
Average
1,440
1,130
1,300
1,210
1,260
     Table 1 shows the average wastewater qualities investigated accord-
ing to the each process of 4 factories.  The ratio of BOD/CODf^/SS was
about 3/2/1.
     In order to project the fluctuation in the influent quality coming
into a wastewater treatment plant, the quality and quantity of waste-
water were investigated in drains which accepted fish processing waste-
water (Fig. 2).
  1500
                                                      18             24
                                                            Time  (hour)
                   Fig.  2   Fluctuation  of BOD
                                   167

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          During the operation hours of the factories, from 8 a.m.  to 4 p.m.,
     the BOD was 730 - 1460 mg/fc (averaging 960 rng/A), but at other times it
     was 200 mg/fc.


2.2  Estimation of  Combined Wastewaters


          The quantity and quality of the combined wastewaters were estimated
     as shown Table 2.

          Fish processing wastewater was estimated to  account for 26% of

     the total inflow at  the start of joint wastewater treatment, and for its

     influent quality, the BOD was 500 - 600 mg/Jl and  the Kjeldahl nitrogen

     was 100 - 150  mg/Jl in most cases.
                    Table  2   Estimation  of combined wastes
                                 1st stage
                    Final stage
     Quantity (m /day)
       Domestic Wastes
         Av.
         Daily Max.
         Hourly Max.

       Industrial Wastes
         Av.
         DaiIt Max.
         Hourly Max.
       Total
         Av.
         Daily Max.
         Hourly Max.
 3,618
 4,576
 6,479

   777
 1,224
 3,672

 4,395
 5,800
10,151
15,200
19,200
27,200


 1,270
 2,000
 6,000


17,200
21,200
33,200
     Quality  (rng/H)
       Domestic  Wastes
          BOD
          SS
       Industrial  Wastes
          BOD
          SS

       Total
          BOD
          SS
   175 mg/£
   158 mg/i

 1,715 mg/H
   556 mg/fc


   500
   240
   175
   158

 1,715
   556
   330
   200
                                   168

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3.    EXPERIMENT AND ANALYSIS

 3.1  Pilot Plant and Experimental Procedures

           Experiments of combined treatment of fish processing waste and
      domestic waste were conducted for about 1 year using an activated
      sludge process pilot plant.
           The flow diagram of the pilot plant is shown in Fig. 3.   Speci-
      fications of major facilities are shown in Table 3.
           The pilot plant was operated in two modes of activated sludge
      process and recycled nitification and denitrification process.
      In the experiments, it was planned to completely nitrify the effluent
      by the addition of alkali in order to assure the effluent BOD at less
      than 20 mg/£, since the influent nitrogen concentration was relatively
      high.  Further, the recycled nitrification and denitrification process
      was studied in summer season to minimized the alkali dose rate.
                                    169

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Apartment
houses
          Reservoir of
          domestic
          wastewater
Bonito drying
factory
-0-
Reservoir of
industrial
wastewater
                                                                    Sludge
                                                                    Reaera-
                                                                    tion
                                                                    tank
                                                                  Return  sludge
Primary
settling
tank
                                                                             Aeration tank

                                                                             Divided into
                                                                             four compart-
                                                                             ments by porous
                                                                             plates
                                                                                                           Effluent
                                     * Also serving as pre-aeration tank
                                                                                                      :  Pump

                                                                                                  M1  :  Flowmeter
                                      Fig. 3  Flowchart of pilot plant

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              Table 3  Specifications of major facilities
Name of facility
Reservoir of domestic
wastewater
Reservoir of industrial
wastewater
Reservoir of influent
Mixing tank
(preaeration tank)
Primary settling tank
Aeration tank
Final clarifier
Return sludge reaeration
tank
Specifications
Effective volume
Effective volume
Effective volume
Effective volume
Diameter
Effective depth
Effective depth Width
1. 08 m x 0. 7 m x
(Divided equally into four
ments by porous walls)
Diameter
Effective depth
Effective volume
2.5 m3
700 £
200 £
50 I
0.6 m
1.6 m
Length
2.0 m
compart-
0.5 m
1.5 m
200 H
     Table 4 shows the operational conditions of the pilot plant
study.
                                171

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                                      Table  4  Operational conditions of pilot plant
No.
1
2
3
4
5
6
7
8
9
Mode of
operation
Activated
sludge process
Activated
sludge process
Activated
sludge process
Recycled
process
Recycled
process
Recycled
process
Recycled
process
Activated
sludge process
Activated
sludge process
Temperature
(°C)
8.9^20.7
(14.0)
11.6VL8.1
(14.5)
11.5^23.6
(16.3)
11.5M.6.4
(14.6)
12.2M6.8
(13.2)
11.5VL5.5
(13.2)
18.5^23.5
(21.7)
8.2^15.7
(12.4)
11.5^15. 9
(13.4)
Aeration
time
(hr)
15.3^25.5
(21.2)
19.5^27.3
(23.8)
19.7V36.7
(24.3)
22.4^25.5
(23.9)
46.8^51.4
(48.5)
23.8^50.0
(35.8)
21.8^27.3
(23.8)
22.9^25.9
(23.0)
24.3^25.7
(25.2)
Return sludge
ratio
(%)
50
100
200
200
100
100
100
100
100/150
BOD loading
BOD-kg
MLSS-kg.day
0.17X5.71
(0.38)
0.21^0.42
(0.30)
0.08^0.75
(0.38)
0.14^0.40
(0.22)
0.08^0.25
(0.12)
0.04^0. 19
(0.11)
0.08^0.30
(0.17)
0.11^1.24
(0.17)
0.24^1.13
(0.17)
MLSS
(g/W
1 . 3^2 . 0
(1.7)
1.9^2.7
(2.2)
1.1^2.8
(1.8)
1.4^4.3
(2.7)
1.3V1.9
(1.6)
0.9^5.2
(3.4)
2.5^4.5
(3.6)
2.4^4.9
(3.7)
2 . 1^3 . 4
(2.8)
SVI
(-)
360^710
(570)
250^400
(290)
130^530
(230)
130^640
(290)
340^730
(520)
89^320
(190)
210^340
(250)
62-V240
(140)
69^98
(86)
SRT
(days)
7^17
(11)
5M7
(12)
8^64
(16)
5^179
(33)
29^32
(32)
16^51
(28)
8^22
(13)
10^16
(12)
14^21
(18)
Effluent
PH


5.9%7.5
(6.8)
5.70-7.5
(6.9)
6.3^7.0
(6.6)
7 . O'W . 4
(7.2)
6.8^7.3
(7.0)
5.8^7.5
(6.7)
6.3^7.8
(6.8)
ro
                                      Figures in parentheses show the average values.

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     The major experimental procedures were as follows:

(1)   The domestic sewage and the bonito processing wastewater,  which
     had been collected in their respective storage tanks,  were homo-
     genized in a mixing tank and fed to the primary settling tank.

(2)   For the fluctuation in the influent BOD loading, the influent BOD
     in the daytime  (9 a.m.  - 5 p.m.)  was set at about 1000 mg/Jl,  and
     the influent BOD in the nighttime (5 p.m.  - 9 a.m.)  was at about
     400 mg/£.

(3)   To fix the wastewater temperature inside the aeration  tank, the
     cooling water was circulated inside the tank through the cooling
     tubes.

(4)   Slaked lime milk was used to control pH in the aeration tank.
     If this milk was allowed to be kept for a long period, it  was
     gradually converted to calcium carbonate.   Therefore,  it was
     prepared immediately before the dosing and added directly  into
     the aeration tank.

(5)   At the early stage, the SVI became 500 or more, so that the raw
     wastewater was  directly sent into an aeration tank bypassing
     the primary tank.   After this, the SVI temporarily fell to 200
     or less, but then rose again.   To improve this condition,  30  mg
     of kaoline per  liter of influent was dosed as an inorganic
     component.

         The pilot plant  experiment was  started with the MLSS  of  2500 mg/Jl
     and the  aeration time of 16 hrs,  and these  operational conditions weie
     modified according  as the  operational performance of the pilot  plant.

(1)   Operation for acclimation of biological sludge  (12  January -  10
     February)
          The seed sludge from the existing wastewater treatment plant,
     was introduced  into the pilot plant for the start of sludge ac-
     climating operation.   The wastewater temperature was around 10°c,
     and the MLSS was 2500 mg/£ when the initial operation was  started.  The
     influent BOD was 250 mg/& and the effluent BOD obtained was 20 mg/£
                                   173

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     or less.   The BOD loading was 0.17 kg/kg-MLSS/day and the SVI was 200.
     However,  the SVI later rose to 400 - 600 and the MLSS fell to 1500 -
     2000 mg/SL.  Therefore, the BOD loading in the tank became 0.24 kg/kg-
     MLSS/day.  At the same time, the carry-over of biological sludge was
     observed and the effluent BOD exceeded 100 mg/SL, but the dissolved
     BOD was maintained at 5 mg/£ or less.

(2)   Case 1  (10 February -  8 March)
          The  experiment was intended to maintain the MLSS of 3000 mg/SL
     at the  aeration time of 16 hrs.   The SVI was as high as 400 - 600
     and it  was impossible to maintain the  MLSS of 300 mg/£.
     Therefore the aeration time was  altered to 24 hrs.   Though ex-
     treme carry-over of biological sludge  was not found, the effluent
     BOD remained at 30 - 60 mg/£.   To investigate the cause of the
     relatively high effluent BOD,  a survey was made of BOD and
     nitrogen  compound distributions  in the aeration tank.   As a
     result, it was found that nitrite was  liable to accumulate in the
     aeration  tank due to the oxidation of  ammonia and organic nitrogen.

(3)   Case 2  (10 March - 29 March)
          The  higher dissolved BOD concentration in the influent
     brought about an MLVSS-MLSS ratio of about 0.9, so that the SVI
     considerably increased.  Therefore, in order to maintain lower
     SVI, the  influent was made to bypass the primary settling tank
     and introduced directly into the aeration tank.  As a result,
     SVI fell  to around 250 and the MLSS attained 1800 mg/SL, although
     the effluent BOD did not become 20 mg/& or less.  Furthermore,
     filamentous microorganisms in the aeration tank disappeared,
     and instead, ciliatea became the predominant species.  The ef-
     fluent  BOD from the final clarifier was found to be higher than
     that of mixed liquor supernatant in the aeration tank because of
     the incomplete nitrification.

(4)   Case 3 (30 March - 8 June)
          For the purpose of  lowering the apparent influent  concentra-
     tion in  the  aeration  tank,  the  sludge  return  rate was  in-
     creased  from 50% to 100  - 200%  and, at the same  time,  the  SRT was
     controlled to depress  the nitrification.  When  the  sludge  return  rate
     was  adjusted to  iOO%  and tha  SRT was  set at  10  days,  the  BOD loading
                              •   174   ''

-------
     in the aeration tank increased with the decrease in MLSS.   Accord-
     ingly, the effluent BOD was not improved.  Further, as the wastewater
     temperature was 16 - 19°C,  nitrification tended to still continue.
     The sludge return rate  was  altered to 200% and the SRT was readjusted
     to 12 days.   As a result,  the SVI fell to 150 and the MLSS rose to 2500
     mg/£.  At this time, the effluent BOD was maintained at 20 mg/& or
     less.  Then, as the settleability of the sludge was improved, the
     sludge return rate and the  SRT were altered to 100% and 40 days re-
     spectively.   Consequently,  the effluent BOD and ammonia beca.ne 10
     mg/a and 0.1 mg/fc respectively, but the pH was lowered to 5.8.
     Therefore, 200 mg/£, of  slaked lime was added to adjust the pH fo
     7.0.

(5)   Case 4 (9 June - 6 July)
          In order to reduce the amount of lime milk required for
     nitrification, the recycled nitrification and denitrification
     process was applied.  In this case, the first compartment  of the
     aeration tank was arranged  to be in an anoxic condition (DO: 0.2
     mg/£ or less).  The wastewater temperature was set at 14°C and,
     in order to maintain MLSS high, the SRT of 30 days was used for
     this operation.   The sludge return rate was set at 200% to in-
     crease the alkaline production in the anoxic compartment as much
     as possible.  Filamentous microorganisms were gradually generated
     in the tank, which resulted in the raise of SVI.  Threfore, this
     experiment was discontinued halfway.

(6)   Case 5 (July - 27 July)
          In application of  the  recycled nitrification and denitrifi-
     cation process,  it was  considered that the BOD loading to the
     aeration tank should be reduced for successful operation.
     Accordingly, aeration time  was set at 48 hrs.   As, however, the SVI
     failed to drop to the desired value and remained at around 500,
     30 mg per litre  of kaoline  was dosed into the tank.   Fifteen days
     from the start of kaoline dosing,  the SVI fell to 350 and  the MLSS
     became 1900 mg/SL.  The  effluent BOD was about 10 mg/£.  The
     nitrification of the effluent reached nearly 100% by dosing the
     mixed liquor with  100 - 150 mg/&  of  lime  milk.

                                 175

-------
 (7)  Case 6  (28 July -  5 October)
          In the previous experiments of  the recycled process,  the
     first compartment  of the  aeration  tank was  arranged  to be  in an
     anoxir  state.  In  order to  reduce  the dosing rate  of lime
     milk, the second compartment was also made  to be in  an anoxic
     condition.  Further, as the MLSS began to rise, the  aeration time was
     gradually shortened to 48 hrs,  40  hrs and  32 hrs.  As a  result,
     the amount of  lime milk required for dosing was decreased  to 50
     mg/d, and the  effluent BOD  reached a stable state  around 20 mg/#.
     At this time,  the  wastewater temperature was 12 -  14°C.

 (8)  Case 7  (6 October  - 31 October)
          The wastewater temperature was  raised  to 20°C,  and  the aera-
     tion time was  shortened to  24 hrs, but the  effluent  BOD  was kept
     to 1.6  - 13.5  mg/£ and nitrification proceeded  almost completely
     with addition  of around 40  mg/£ of slaked  lime.

 (9)  Case 8  (1 November - 28 November)
          In Case 8 and subsequent experiments,  the  operational mode
     was changed to the activated sludge  process with lime milk addi-
     tion.   In Case 8,  investigation was  made  to stabilize the  efflu-
     ent quality of BOD 20 mg/£  under 24  hour  aeration  and wastewater
     temperature of 12  to 14°C.  As  a result,  300 mg/£  of dosing
     slaked  lime brought about an effluent BOD of 11.7  mg/Jl  and a
     nitrification  rate of 95%.

(10)  Case 9  (29 November - 17  December)
          The effect  of the  influent quality  fluctuation  upon the
     effluent BOD was  investigated.  For  this  purpose,  the influent
     BOD was set at 1000 mg/&  for  the daytime  (9 a.m. - 5 p.m.),  and
     at 400  mg/£ for  the nighttime  (5 p.m. -  9 a.m.).   The pilot plant
     was operated  at  25 hr aeration  time  and dosing rate  of  about 250
     mg/£ of slaked lime.  As  a  result, the  effluent BOD attained 3.1
     - 11.6  mg/fc.
                               176

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3.2  Results

 3.2.1  Analytical  Results

             Table  5  shows the  overall  analytical  results  of  the pilot
        plant experiments.

 3.2.2  Influent  Quality

            The influent BOD was 200 - 1000 mg/£, averaging 600 mg/Jt
       approximately.  The ratios of BOD to other wastewater quaility indices
        become higher as BOD  increases, but within the  range  of BOD  fr^m
        500  to 700  mg/£,  the  ratios  are as  follows:
                                        177

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                                                 Table 5  Analytical  results

1
2
3
4
5
6
7
8
9
T-BOD
(mg/4)
In.
284^1150
(547)
407^963
(656)
236^1500
(615)
286^725
(544)
179^593
(384)
188^1060
(538)
301^968
(593)
355^885
(628)
311^800
(494)
Eff.
18^171
(56)
10^95
(46)
16^153
(62)
7^69
(24)
5^12
(7)
3^35
(14) '
2^14
(5)
2^23
(12)
3^12
(6)
SS
(mg/£)
In.
51^148
(89)
92^803
(202)
80^266
(153)
96^540
(221)
165^513
(240)
178^720
(313)
163^735
(310)
193^377
(270)
120^308
(204)
Eff.
6^64
(25)
8^49
(28)
10^73
(35)
5^85
(24)
6^13
(12)
2^32
(7)
3^31
(9)
2^22
(9)
2^9
(5)
KJ-N
(mg/£)
In.



90.7^152
(118)
92.0^142
(117)
84.0M71
(129)
102^154
(126)
50.1M93
(126)
69.7^142
(104)
Eff.



0.7^23.7
(5.5)
0.4^1.6
(0.9)
0.3^48.6
(16.4)
0.6^24.2
(5.3)
0. 3^23.9
(6.0)
0.1^6.1
(1-5)
NH^-N
(mg/£)
In.

49.0^117
(90.7)
18.4^210
(69.7)
27.8^81.0
(48.5)
30.5^60.5
(42.3)
20.9^102
(60.6)
46.0^116
(84.4)
15. 3^162
(79.8)
43.9^78.7
(59.6)
Eff.

10.5^41.5
(27.0)
0^39.4
(10.4)
0^15.3
(2.6)
0 . 1^2 . 1
(0.6)
0.1^45.8
(10.9)
0.1^22.7
(3.8)
0^22.9
(1-9)
0^2.8
(0.7)
NO^-N
(mg/£)
Eff.

6.7^17.5
(11.7)
3. 3^31.4
(14.2)
0.03^17.0
(3.9)
0 . 3^4 . 6
(1.6)
0.01^1.58
(0.69)
0.04^2.0
(0.62)
0.14^15.5
(7.9)
0.8^4.5
(2.3)
NO~-N
(mg/£)
Eff.

0^12.5
(4.2)
crolO-. 5
(3.4)
1.2^56.8
(15.3)
0 . 6^8 . 3
(4.8)
2.rul5.9
(6.2)
6.5^15.5
(10.1)
5 . 4^45 . 2
(26.7)
35.7^39.9
(31.8)
Alkalinity
(mg/£)
In.


150^349
(260)
180^417
(319)
287^386
(347)
242^409
(324)
251^401
(328)
147^343
(292)
160^340
(274)
CD
                                   Figures  in  parentheses show the average values.

-------
            To CODm               2.8
            To Suspended Solids    2.16
            To Total Nitrogen      5
            To Total Alkalinity    1.8
            The ratio of BOD:N:P was 40:8:1.   Compared with ordinary
       municipal wastewater, the nitrogen content was comparatively high.
       Further, the values of wastewater quality indices other than BOD,
       in most cases, were as follows:
            COD^jp            :   About 200 mg/£
            Suspended Solids :   About 250 mg/£
            Alkalinity       -.   250 - 350 mg/X,
            Nitrogen         :   Both nitrite  and nitrate were scarcely
                                present in the wastewater.   Kjeldahl
                                nitrogen was  100 - 150 mg/£ and about a
                                half of it was accounted for by ammonia.
            Phosphorus       :   The total phosphorus was 10 - 20 mg/£ and
                                60 - 80% of the phosphorus  was orthophos-
                                phate.
            Normal Hexane    :   20 mg/S- on the average.   When the overflow
            Extract Substance                          .
                                from the caldrons came into the waste-
                                water, 300 mg/£ was reached due to the in-
                                creased oil and fat contents.

3.2.3  Operational Conditions of Aeration Tank

            When a primary settling tank was  installed and  the effluent
       from the tank was introduced into an aeration tank,  the MLVSS/MLSS
       ratio became 90% or more.   Because of  relatively low content of
       inorganic matter^ the settleability of activated sludge was poor.
       Therefore,  the influent  was made to bypass the primary settling tank
       and to flow directly into the aeration tank.   As a result, the MLVSS/
       MLSS ratio went down to  80%,  and SVI was lowered from 500 to 200.
       After this,  the settleability of sludge became worse again,  so that
       30 rag of kaoline per liter was introduced into the mixed liquor.   As a
       result,  SVI was improved.   SVI was lowered when Sa-t [Sa: MLSS (g/£),

                                     179

-------
       t: aeration time  (hours)] became high.  SVI was corrc-lated with Sa-t
       and wastewater temperature as follow:
            SVI = 922.1 - 17.5  (WT) - 7.3  (Sa-t) 	(1)
            Where,
            WT = Wastewater temperature (°C)
            Operational condition under the stable state were as follwos:
            The 90% reduction of dissolved BOD was completed in the first
       compartment of the aeration tank, when the activated  sludge process
       was applied.  The nitrification showed almost the same tendency as
       the reduction of dissolved BOD.
            When the recycled nitrification and denitrification process  was
       applied with two anoxic compartments, 60% of dissolved BOD was
       reduced at the end of the first compartment and 90% of dissolved
       BOD was reduced at the end of the second compartment.  And nitrate
       became about 0.1 mg/fc at the end of the first compartment, about  5
       mg/£ at the end of the second compartment and about 12 mg/£ at the
       end of the third compartment and about 14 mg/£ at the end of  the
       fourth compartment of the aeration tank.
            In either the activated sludge  process  or the recycled
       nitrification  and denitrification process,  the oxygen utilization
       rate was estimated at 1.1-1.2 times  the  BOD removed.   As for the
       activated sludge  microorganisms,  when the effluent quality was fa-
       vorable, ciliatea became the predominant  species.   Especially when
       SVI and the MLVSS/MLSS ratio were comparatively low,  aschelminthes
       appeared.   Further,  rhizopodes,  especially Arealla were found when
       the nitrification was progressing favorably.

3.2.4  BOD loading vs. Efficiency

            The relationships between BOD loading and BOD remaining rate
       are shown in Fig. 4.  In winter season,  the BOD loading was required
       to be 0.2 kg/kg.MLSS/day or less for the activated sludge process
       and 0.1 kg/kg.MLSS/day for the recycled process in order to get the
       BOD remaining rate of 3.3%, or the effluent BOD of 20 mg/£.
                                  180

-------
10

Q) c
m
C
•H
c 2 -
•H ^

-------
3.2.5  Alkali  Balance for Nitrification

            The  alkalinity which is consumed when organic nitrogen and
       ammonia are converted to nitrate are theoretically 3.57 mg/& and
       7.14 mg/£ respectively.   The average content of Kjeldahl nitrogen
       in the  influent  was 125 mg/£,  of which about 1/2 was ammonia.   The
       alkalinity of the influent was  323 mg/£.   Accordingly,  in the
       activated sludge process, the shortage in alkalinity was calculated
       as follows:
               (125 x 0.5 x 3.57 + 125 x 0.5 x 7.14)  - 323 = 346 (mg/£)
            In addition, the residual  alkalinity, which was required to
       maintain  the pH of effluent around 7, was about 50 mg/£.  Total
       alkalinity of 400 mg as  CaCC^ is equivalent to slaked lime of
       300 mg  approximately.  Therefore the actual dosed amount of  slaked
       lime (= 300 mg/Jl) coincided with the calculated one.  In the
       recycled process which was applied at the influent  temperature
       of around 20°C, the slaked lime dosed was only  40 mg/£.  The
       relationship between the actual and the calculated amounts of
       alkali  consumption are shown in Fig. 5.
                                  182

-------
       ffl
       Tf
       o
       U
           600
           40°
           200-
           100-
.'   '/ •
  ••*•  V
                                /
                                         o

        .  /'
         V
                                               0
                                               o
                                            o
      100   200         400
          Actual value  (mg/£)
                                            O  Activated sludge
                                               process
                                            •  Recycled  process
                                                 600
              Fig.  5  Comparison of alkali consumptions
3.3  Analysis
          In analyzing the results of the pilot plant experiments, the fol-
     lowing multiple regression model was used.
                                           ..an
               X,
                                                                (2)
Where,
                         Y :   dependent variable
                         Xjj:   independent variables
          The data used in the multiple regression analysis were mostly  the
     operational results of the activated sludge process.  Table 6 shows
     the single correlation coefficients of the major operational parameters
     of the activated sludge process.  WT, MLSS, BOD-SS loading, F/M, and Sa-t
     have large correlation coefficients to BOD remaining rate, and these
     values are more than 0.74.  On the contrary, since aeration time and
     influent BOD were not altered much during the experiments, their correla-
     tion coefficients to BOD remaining rate were rather small.
                                       183

-------
                                           Table  6   Single correlation coefficient
\
R • T
W • T
IN BOD
TTJ BOD
IN COD
MLSS
MLVSS
BOD-SS
OUT BOD
SVI
R
SRT
F/M
IN- BOD
T/S
BOD re-
maining
rate
k1
R - T
1
0.46
0.43
0.10
0.27
-0.39
0.47
0.41
-0.20
-0.05
0.07
0.58
0.09
0.17
0.16
W . T
0.46
1
-0.11
0.04
-0.87
0.10
0.85
0.73
0.26
0.00
0.16
0.83
0.23
-0.75
0.84
IN
BOD
0.43
-0.11
1
0.50
0.18
-0.32
0.26
0.27
0.03
-0.23
-0.09
0.32
0.26
-0.12
-0.30
IN
BOD
COD
0.10
0.04
0.50
1
-0.23
0.09
0.42
0.33
0.05
0.51
0.30
0.37
0.45
0.12
0.19
MLSS
-0.27
-0.87
0.18
-0.23
1
-0.34
-0.87
-0.82
-0.45
-0.17
-0.03
0.79
-0.49
-0.89
-0.89
MLVSS
-0.39
0.10
-0.32
-0.09
-0.34
1
0.01
0.23
0.65
-0.17
0.10
-0. 16
0.05
0.33
0.15
BOD-SS
0.47
0.85
0.26
0.41
-0.87
-0.09
1
0.92
0.40
-0.04
-0.09
0.97
0.46
0.82
0.78
OUT
BOD
0.41
0.73
0.27
0.33
-0.82
0.23
0.92
1
0.60
-0.13
0.08
0.85
0.47
0.91
0.57
SVI
-0.20
0.26
0.03
-0.05
-0.45
0.65
0.40
0.60
1
-0.58
-0.10
0.22
0.24
0.64
0.19
R
0.00
0.00
-0.23
0.51
-0. 17
-0.17
0.04
0.13
-0.58
1
0.44
0.10
0. 31
0.06
0.30
SRT
0.10
-0.16
-0.09
0.30
0.03
-0. 10
-0. 10
0.08
-0.10
0.43
1
-0.11
0.23
-0.10
-0.17
F/M
0.58
0.83
0.32
0.37
-0.79
-0.16
0.97
0.85
0.22
0.01
-0. 11
1
0.44
0.74
0.74
IN-
BOD
T/S
0.09
0.23
0.26
0.45
-0.49
-0.05
0.46
0.47
0.24
0.31
0.23
0.44
1
0.42
0.31
BOD
remain-
ing rate
0.17
0.75
0.12
0.12
0.89
0.33
0.82
0.91
0.64
0.06
-0.10
0.74
0.42
1
0.70
Sa-t
-0.22
-0.86
0.19
-0.24
1
-0.36
-0.87
-0.81
-0.46
-0.18
-0.03
-0.78
-0.49
0.89
-0.89
oo
       Where,    RT:   Aeration time
                 WT:   Mixed liquor temperature
            BOD-SS:   BOD-SS loading
  R:   Return sludge ratio
T/S:   Total/Soluble
  k':   -{log(OUT-BOD/IN-BOD)}/RT x MLSS
Sa-t:   RT x MLSS

-------
3.3.1  BOD Remaining Rate
            For BOD remaining rate, the following equation was obtained.
               BODp D  = 8.923 x (WT)
                  1\» Xv •
                      ~°'566
                                (Influent BOD)
                               -1.71
                                                            °'467
                  R. R.
Where,
BOD,
WT
Sa
t
             x (Sa-t)'    	  (3)
(multiple  correlation  coefficient:   0.941)


 BOD remaining rate (%)
 Wastewater  temperature  in aeration tank  (°C)
 MLSS (g/£),  and
 Aeration  time (hours).
            Fig.  6 shows the relationship between the measured and the
       calculated values of BOD remaining rate using the equation.
                20
                10 •
             •P
             (fl
             
-------
     tr
     C
        1 f^,	 	
        LVJ
                               SO
80
                                                     100
                                                    Sa-t (g/!i-hr)
                  Fig.  7  BOD remaining  ratt  vs.  Sa-t
          Th i <- figure shows in  irder f  >b' ain  the  BOD remaining rate of
         ,  namt ;y, effluent B(>P  is  0 mg- v1 ,  Sa't  should be kept more
          ?2 .-) \; Si-hr and more r nai ^S.-i  g/'_-hr to  water temperatures ot
     14°   and 20 °C, respective ty.
          Baser upon this, the relationship  between aeration time and BOD
     remaining rate for winter season is  shown  in Fig. 8.
   10
    8
    S	
tr
c
D
O
CO
                           8    10
                                                                    I  (mg/fc)
                                                                     2000
  16         20        24
      Aeration time  (hours)
               Fig. 8  BOD remaining  rate  vs.  aeration time
                       when water  temperature  is 14°C
          It is known from this  figure  that in order to obtain the
     effluent BOD of 20 mg/£  in  winter,  it is required to keep MLSS at
     some 2620 mg/X, for the aeration  time of 24 hrs.
                                    186

-------
3.3.2  Nitrification Rate

            For the nitrification rate, the following equation was obtained
       to the variables of mixed liquor temperature, Sa-t and influent
       total nitrogen.
            1 - N.R.  = 18.578 x (WT) 1'901x (Sa-t)'2'834
x (Influent nitrogen)
  (Y=0.899)
                                                    2.263
                                                                   (4)
            Where,
            N.R.  :   Nitrification rate (%)
            The relationship between the measured and the calculated values
       of (1 - nitrification rate)  is shown in Fig. 9.

20 -
; 10-
M 8 •
t) c
 '
-P
1 3-
, — |
03
° 2-
1 -
0.5
• /
' \/ '
m /
s
y'
s
s •
s
• , . •
• • /'
/' f

               °-5     1       23      5    8 10     20  30   50
                             Measured value  (%)

                     Fig.  9  (1 - Nitrification rate)
                                    187

-------
     Fig. 10 shows the relationship between Sa-t and  (1 - N.R.) at
temperatures of 14°C and  20°C,  and  influent total  nitrogen  concentration
of 130 mg/£.
   100
    80

    50
    20
    10
2
I
                            \
                           A
                           20°C\
                                   \
                                         \

                                           \
                                               \
                                              \

                                                 \
        0    10    20    30    40    50    60    70
                                        Sa-t (g/£-hour)

               Fig. 10  (1-N.R.)  vs. Sa-t

     From this figure, it is found that Sa-t required to obtain the
nitrification rate of 90% is 52.5 g/£-hr in winter.  Accordingly,
it is known from figures 7 and 10 that nitrification rate can reach
90% if only Sa-t exceeds the value that satisfies the BOD remaining
rate of 3.3%.
                             188

-------
3.3.3  Oxyqeri Demand


            The relationship between mixed  liquor  temperature and oxygen

       utilization rate (02 UR) is shown  in Fig. 11.
                 11   li   13  1>«   15   16   17   18   19  20

                                  Mixed liquor  temperature  (°C)


              Fig.  11  Mixed liquor temperature vs. 02 UR


            From this figure,  02 UR is expressed in the

                                      (T-20°C)
               O2  UR = 20.1 * (1.0688)
(5)
            Fig.  12  shows the relationship between 02 UR and BOD  removal

       at the water temperature of 14°C.
0.4

0.3-
i
T3 0.2-
CO
2
D 0.1 •
CM
o
n







y





•
.^
7*





• yi
.-Xy:
^;



• y^
/
/
*
L.0002x +
(r=



t
(Mixed requor
temperature
14°C)
0.0434
3.83)



                      0.1       0.2      0.3       0.4
                                        BOD removed/MLSS  (day"1)
                   Fig. 12  O2  UR vs.  BOD removed
                                  189

-------
3.3.4  Sludge Production


            Since the  excess sludge produced was not expressed well in

       multiple regression  equation,  the data were processed through the
       following equation.
               AS  =  a-Lr -  b-Sa'
(6)
              Where,  AS  :   Sludge  production (kg/day)

                     Lr  :   BOD removed (kg/day)

                     Sa1:   MLSS in the system (kg)

                     a   :   Proportion  of Lr that is synthesized and
                           converted to new cell

                     b   :   Endogenous  respiration rate  per day.

            Using  this equation, Fig.  13 was obtained,  which shows the

       relationship between BOD removed and sludge production.

0 18-
0 15-
o i ? -
rH
i
>? 01-
ts u- J-
ti
One? -
W
<3 n rm -
n n? -
0








/





•
/
/'•





/
//
^





/
f.





^
/









y=0. 3992x-0.00
(r=0.924)










38


/ 0.1 0.2 0.3 0.4 0.5 0.6
                                                    Lr/Sa1  (day"1)
                 Fig.  13   Relationship  between  BOD removed
                           and  sludge  production
                                  190'

-------
3.3.5  Sludge Thickening Ratio in Final Clarifier

            It was considered that the sludge thicknening characteristics
       and the return sludge concentration could be judged by thickening
       ratio  (= Return Sludge concentration/MLSS).  As MLSS rose, the
       thicknening ratio tended to fall.  When MLSS was around 3000 mg/i,
       the thickening ratio became 1.8 - 2.2.
            For solid loading, following equation was obtained.
               Solid loading (kg/m2/day) = -81.97- (thickening ratio)
                                           + 190.5 	    (7)
            Fig. 14 shows this relationship.
         !3
         s
                      10
20
30
40
                                          Solid loading (kg/m2/day)
                    Fig. 14  Solid loading vs. thickening ratio

            A relation between thickening ratio and SVI was not found
       clearly.

3.3.6  Effluent Characteristics

            An investigation was made on the relation between effluent
       BOD and ammonia and nitrite.   When the effluent nitrite and ammonia
       were 1 mg/£ or less, the BOD  of the suspended solids portion of the
       effluent (hereinafter refers  to (T-S)  BOD)  was 10 mg/£ or less.  On
       the other hand, when the effluent nitrogen was nitrite type contain-
       ing the nitrite of 15 mg/£ or more, (T-S)  BOD to suspended solids
       ratio was nearly 1.0.  When the nitrogen in effluent was ammonia type
       and the ammonia concentration was 10 mg/& or more,  (T-S) BOD/SS
       ratio =2.0-2.5.  In either case, (T-S)  BOD mostly became 20 mg/£.
                                     191

-------
     Figures 15 and 16 show the relation between effluent  SS  and
effluent (T-S)  BOD.
 100

                                             o NO2 >15 mg/£
                                               NH,, > 10 mg/£
                                          100
                                              SS(mg/£)
        Fig. 15  Effluent SS vs. Effluent  BOD in SS

6 10 '
Q
O
CQ
Effluent (T-
o u


'
' . V



•


• *
" • s •
•





NO2 < 1 mg/£
NH., < 1 mg/£

05 10 15 20 cefmri/n
       Fig.  16  Effluent  SS  vs.  Effluent BOD in SS
                             192

-------
3.3.7  Nitrogen Removal in Recycled Process

            The relation between nitrogen removal and BOD removal in  Re-
       cycled Nitrification and Denitrification Process was analyzed.
            The denitrification reaction is expressed as follows:
               2NO  + H2O -»•  N  + 20H  + 5(u)
                                      (8)
            Therefore, the theoretical amount of BOD required  for  1 mg of
       nitrate removed is:
                    16
                    14
                        = 2.86
            Fig.  17 shows the relation between the nitrogen removed and
       BOD removed in the denitrification compartments of recycled process.
      TJ
      i
      Q
      O
      CQ -
          300 -
          200 .
          100 •
                a :  in the first compartment
                y :  in the second comaprtment
^- 01.27
 °-°88  1°.55
                                                    2,  the following equation was
      obtained.
              BODr  =  3.487 Nr  +  51.7
                                                                      (9)
              Where,
                Nr   :   Nitrogen removed (g/day)
                BODr:   BOD removed (g/day)

                                   193

-------
     The slope 3.487 indicates the BOD consumed  for denitrification,
which is about 20% higher than the theoretical value  of  2.86.
     The constant 51.7 indicates that there existed a portion  of
BOD removed by other than denitrification.
     This suggests that the initial adsorption of BOD by micro-
organisms might occur.  Fig. 18 shows the relation between the
amount of nitrification and BOD removed.
QJ
3
      id  cr>
          4 -,
          3 -
      3 ^
      en  u
     0 -H
     6 -u
     0) 
-------
   10CH
*  50

rt  30
&>  20
c.  15
              e
              o  o
o in the  first  compartment
• in the  second compartment
  100
      0     10      20     30     40    Sa-t (g/£-hrs)

0  30
n
s  20-1
      012345         8      10    12
                Aeration time  (hrs)
     Fig. 19  Nitrogen  remaining rate vs.
              Sa-t  and  aeration time

     From Fig. 19,  nitrogen  remaining rate is obtained as follows:
        log  (Nitrogen  R.R.)  =  -0.072t + 2.003 	
                                       (r = 0.78)
        Where,
          t  :  Aeration  time (hours)
          Nitrogen  R.R.:   Nitrogen Remaining Rate (%)
                       (10)
                              195

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4.   CONCLUSION

         In the pilot plant experiments,  it was found that the complete
    nitrification of the effluent was required by adding alkali to the
    aeration tank in order to assure effluent BOD of 20 mg/£ through the
    biological treatment of the combined  wastewater having a BOD of 600
    ing/4 and a nitroqen concentration of  100 - 150 mg/£.
         Design temperature of the influent in winter season was set at
    14°C.
         Under this condition, the following design and operational concepts
    were recommended to obtain the stable effluent BOD of 20 mg/JL

    (1)   The flowchart of the combined wastewater treatment plant is pro-
         posed as shown in Fig. 20.

    (2)   An aeration tank should be designed to have 4 divided compartments.
         And the first one or two compartments should be able to be kept
         under anoxic condition in case of the recycled nitrification-de-
         nitrification process.

    (3)   In winter season when the wastewater temperature is 14°C or less,
         the plant is to be operated in the activated sludge process mode
         of 24 hr-aeration and the effluent pH should be controlled by
         adding a maximum 300 mg/£ of slaked lime.
                                   196

-------
                                                                    Kaoline  Slaked  lime
  Influent
vo

Grit
Pump

Thicke
tank
chamber Primary F
cnamoer 	 — ... i n^lanHna .. A°ratHi"n «-
settJinq nni.aii.ing _ rcinon 	 _ c
P tank tank rl tank
| !
1 \ 
-------
(4)   It  is  possible  to reduce  the  lime addition rate to 40 mg/£ if the
     plant  is operated in  the  recycled nitrification denitrification
     mode of  32  hr-aeration  time,  in winter season.

(5)   In  summer season  when the influent temperature  of 20°C or more, the
     plant  is to be  operated in the  recycled nitrification-denitrifica-
     tion mode of 16 hr-aeration time with the addition of 40 mg/£ of
     slaked lime.

(6)   An  overflow rate  of 15  m3/m2/day should be adopted for the final
     clarifier because of  high organic content of the activated sludge
     and its  resultant poor  settling characteristic.

(7)   It  is  preferable  to add kaoline to the aeration tank in order to
     improve  the settling  characteristic of the activated sludge.
                                198

-------
                                      Eighth US/JAPAN Conference
                                              on
                                      Sewave Treatment Technology
      TECHNICAL EVALUATION
                       OF
DEEP WELL BIOLOGICAL PROCESS
                  October 13-14,1981

                  Cincinnati, Ohio USA
    The work described in this paper was not funded by the
    U.S. Environmental Protection Agency.  The contents do
    not necessarily reflect the views of the Agency and no
    official endorsement should be inferred.
               M. Kuribayashi and K. Murakami

               Water Quality Control Division,

               Public Works Research Institute,

               Ministry of Construction




                        199

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1.    TECHNOLOGY EVALUATION SYSTEM

          The Ministry of Construction  has a technology evaluation system for
     promoting actual use of new and practical  technologies  for public  works
     developed by  private companies.  In  this system,  the Ministry of
     Construction  publicly announces a  particular  technology to be evaluated
     and the goals to be achieved by that technology,  and  invites private
     companies to  submit their  own development  techniques  for this evaluation.
     After applications are received, the applicants are required to
     conduct an experiment for  about one  year to provide data to  determine
     whether the goals are achieved by  their techniques.   Then, the Ministry
     of Construction will evaluate the  results  of  the  experiment, and the
     results of any additional  experiment that  the Ministry  may specify.
     This evaluation is conducted by a  committee consisting  of engineers
     from the Ministry of Construction  and local governments, and college
     professors specializing in each particular technological field.
          A public announcement was made  in June 1979  regarding the project
     evaluating "Deep Well Biological Process for  Sewage Treatment".  Two
     companies, I  and K, applied for this evaluation,  and  in fiscal year
     1980 the Ministry of Construction  evaluated the techniques of these  two
     companies. The evaluation was completed in July  1981,  and the results
     of the evaluation will be  described  in this paper.
          The conclusions of the evaluation are summarized as follows:
          Both of  the techniques attained the publicly announced  goals, and
     judging from  the treatment capacity  and the actual operation, they
     reached the stage of practical use as a municipal sewage treatment
     technology.

     (1)  These were practical  techniques with  a treatment capacity of
          1,000 m3/day or more.

     (2)  These techniques were capable of meeting the legal requirements
          for biochemical oxygen demand(BOD) and suspended solids(SS)  in
          effluents.  The requirements  are 20 mg/1 for BOD and 70 mg/1  for
          SS.
                                   200

-------
(3)   In the operation of facilities under this  process,  there was  no
     marked difference between these techniques and the  conventional
     methods such as  the conventional activated sludge process (herein-
     after referred to as "conventional method").

(4)   As for the operation and maintenance cost, these techniques did not
     differ greatly from the conventional method.

(5)   These techniques had simplicity in taking  countermeasures to prevent
     possible detrimental effect on the surrounding environment.

(6)   Much less land area was required for the aeration tank in this
     process,  compared with the conventional method.
                                   201

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2.    OUTLINE OF TECHNOLOGY TO BE EVALUATED

          The technology selected as the object of the evaluation is called
     the "Deep Well Biological Process for Sewage Treatment".
          The deep well biological process is a type of activated sludge
     process with a deep well shaped aeration tank of about 50 - 150 m
     depth which utilizes a high hydrostatic pressure for improvement in the
     dissolution rate and utilization ratio of oxygen in the air and, at
     the same time, reduces the land area required for the sewage treatment
     facilities.

 2.1  PRINCIPLES

           As shown in Fig. 1, the aeration tank of this process is a deep
      well type aeration tank having a depth to over a hundred meters.
                                   202

-------
Air
 Compressor
               Influent
Head
tank
G
              Air for
              circulation
              Air for
              oxygen
              supply
                                       .*—  Return
                                     V V V
                                                   Vacuum Degasser
                                Downflow Tube
                                              Upflow Tube
                                               Lining
           Fig.  1-a  Deep well aeration tank of Company I
                                 203

-------
   Circulation
       pump
                  Air     Return sludge
                              Pumped water tank
  Upflow tube
                                           To floatation
                                           tank
                                          Relay tank
                                  Down flow tube
Fig. 1-b  Deep well aeration tank of Company K
                           204

-------
     This aeration tank is composed of an upflow tube, a downflow tube, and
     head tank.  The head tank is provided for releasing spent air from the
     aeration tank, through which the mixed liquor is circulated.
          Two companies, I and K, applied for technical evaluation of
     the deep well biological process.  The circulation systems of two
     companies were different from each other.
          Company I employed an "air-lift system" for circulation, in which
     the mixed liquor is circulated by injecting air into the upper portion
     of the upflow tube.
          Company K employed a "pump system", in which a recirculation pump
     is installed between the relay tank and the downflow tube.

2.2  SYSTEM AND FUNCTIONS OF PLANT

 2.2.1   System

             Fig. 2 shows the total system of a sewage treatment plant
        employing the deep well biological process in comparison with the
        conventional method.  (Fig. 2-a shows the plant of Company I, and
        Fig. 2-b, that of Company K.  In the figures and tables, the plants
        of Companies I and K are referred to as "a" and "b", respectively.)
                                       205

-------
Effluent §

J






- 1
0) | 	 [
§ r
H •
« |_.
"^v
.£/ '

•









|
(




r^
P
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	 I


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- — H









JA
X
^fZ\
•H
u
u
 IU4J 9J «) S JT C -ul
8 3 g-H tO C 4J -H (U
01 (U-H 7! M HI 0 J£
v o o i -H *j e ^
: O M nj C T3 4J 19 fl
} &-.4JU-I V 01 -H -U 4J C
1 S 1 S 1 § 3 »
i 1 nj ki Bj > ' O
X -C >i Si 0 01 O A
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(U
Ul | 0)
L>V| O O 0)
^LN > > | la
IE
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1 ~1 0
\ 1 /• \ g m
^ V J 1 w ' ui
•s E, S i §
C /^v'l Oi °
<3 f'T g i w
•p >-A| o 1 a
_ -i -J q
Q <" - - 1 Q-
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(JJ ^J
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                               206

-------
                  Raw  —
                  sewage
                        Grit
                        chamber
Primary
sedimenta-
tion |—
tank I
                                        I
                           To sludge
                           treatment
                           facilities
ro
                                                                                                     Efflue-t
           Disinfec-
sedimenta- tion tank
tion tank
    In the deep
    well biological
    process a scum
    skimmer is
    installed in the
    final sedimenta-
    tion tank.
                                                                              To sludge   I
                                                                              treatment
                                          Return
                                          pump
                                      ^    facilities
                        Sludge storage^ Excess sludge  '
                  	  	tajik	  _  _  	pump _ 	 _ J
                                  Fig. 2-b  System diagram of Company K's process compared
                                            with the conventional process

-------
2.2.2  Deep Well Aeration Tank

            The aeration tank of this  process  consists  of  a deep well  type
       aeration tank and a head tank;  the deep well aeration tank being
       composed of a downflow tube  and an upflow tube.   (In the  system of
       Company K,  the tank corresponding to the head tank  is called the
       "relay tank".)
            In the system of Company I,  the mixed liquor in the  tank is
       circulated at a velocity of  0.7 - 1.5 m/sec by the  air lift produced
       by injection of air into the upper portion of the upflow  tube.
       The influent flows into the  head tank where it is mixed with return
       sludge, and flows down the tube.   Air is also injected into the
       downflow tube.   The velocity of the downward flow is higher than
       that of rising bubbles.  Bubbles are, therefore, carried  downward
       with the downward flow, and  their diameter is consequently reduced.
       When the bubbles reach the bottom of the tank, they move  into the
       upflow tube and rise up the  tube to the head tank,  and conversely
       increase their diameter.  As the injection of air into the downflow
       tube is made at 40 m or more below the  surface,  the specific gravity
       in the upper portion of the  upflow tube becomes  smaller than that
       in the upper portion of the  downflow tube, generating the air-lift
       effect.  In this way, the liquor is repeatedly circulated for biolo-
       gical treatment.  The mixed  liquor is then transferred to the solids
       separation system.
            In the system of Company K,  the deep well aeration tank is
       composed of a deep-well tank comprising a downflow  tube and a upflow
       tube, and of a relay tank.  The mixed liquor in  the aeration tank
       is circulated by a recirculation pump.   The influent which flows
       into the relay tank is mixed with return sludge  and flow downs the
       tube at a velocity of 1 - 2  m/sec, and  through the  recirculating
       pump.  In this system, air is injected  into the  downflow tube, and
       bubbles rise up to the relay tank through the upflow tube.  The mixed
       liquor that has been treated bilogically is transferred to the
       solids separation system.
                                 208

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2.2.3  Solids Separation System

            The mixed liquor transferred from the deep well aeration tank
       contains large quantities of supersaturated dissolved gas and fine
       bubbles;  therefore, a part of the sludge comes to the surface of the
       liquor and a part of the sludge precipitates.  The following
       combinations of methods are considered as viable solids separation
       systems.

       a)   Deep well aeration tank — Vacuum degasser -- Final sedimenta-
           tion tank

       b)   Deep well aeration tank — Mechanical degasser — Final sedi-
           mentation tank

       c)   Deep well aeration tank — Floatation tank — Final sedimenta-
           tion tank

       d)   Deep well aeration tank — Floatation tank — Degasser —
           Final sedimentation tank

       e)   Deep well aeration tank — Floatation tank

            Company I employed combination(a).   The solids separation
       equipment of Company I is shown in Fig.  3-a.
                                       209

-------

i —
(Shower
water
	 H




^
/
1
y
,
II
vJJ

	 —- vacuum pump
^
^^. Outer tube
^^- Inner tube
T« 12rn »
I1 t1
. 0 	 .. f I 1 II1
U II 	 nf
u Id 	 ._LJ kM.
T —U 	 p_ J| ^
-| , r i_/ ^ 	 • — =!





U— f •"
5^
| '
                                                          Effluent
Fig. 3-a  Solid separation facilities of Company I's
          process (vacuum degasser — final sedimentation
          tank)
                        210

-------
                The  vacuum degasser is  composed of an upflow tube and a downflow
           tube,  and the  prescribed degree  of vacuum (0.3  atm abs.)  is applied
           by a vacuum pump.   The  fine  bubbles in the mixed liquor are released
           from the  liquor through the  vacuum degasser.  The mixed liquor is
           transferred from the  deep well aeration tank  to the final sedimenta-
           tion tank through  the vacuum degasser by siphonage due to the dif-
           ference in the liquid levels between the head tank and the final
           sedimentation  tank.   The solid-liquid separation is conducted in the
           final  sedimentation tank.  A part  of the separated sludge is return-
           ed to  the deep well aeration tank.
               Company K,  on the  other hand,  employed combination(d).
           The solid-liquid separation  system of K Company is shown in
           Fig. 3-b.   The mixed  liquor  is sent to the floatation  tank shown in
           Fig. 4 for solid-liquid separation.
                                              pj  Blower
Mixed liquor
from aera-
tion tank
                                        Degasser
                                                                        Effluent
                                                           Final
                                                           sedi:
                                                           tank
                                                                      Scum pit
                            Sludge storage
                                 tank
          Fig.  3-b  Solid separation facilities of Company K's process
                    Cfloatation tank — degasser — final sedimentation
                    tank)
                                       211

-------
Mixed liquor
from aeration4-
tank
          r -
          I
                                                   I	
                               rr i  E
                                                                     To degasser
                                                           Floated sludge
                                                                 i
                                                                 i
            Settled sludge
             Pig.  4  Floatation tank of Company K's process

        The  floatation  tank has sludge  collectors  which  are  operated continu-
        ously  and  the collected sludge  is  returned to  the  aeration  tank.
        The  solid  concentration of  the  floated sludge  is very  high,  which
        makes  it possible  to maintain high MLSS in the aeration  tank.
             In the  effluent from the  floatation tank, suspended solids
        having extremely fine  bubbles on their surface still remain, and
        therefore  the liquor is aerated and mixed  in the degasser to separate
        the  bubbles  and make the sludge precipitates  readily.   In the degasser,
        a diffuser as shown in Fig.  5 is provided  for  diffused aeration.
                                      212

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                                  r
           From  floatation
           tank
                                                             Blower
                                               To final
                                               sedimentation tank
               I
From degasser—>
                               Fig.  5  Degasser
                             L_
                                                                         Scum
                                                                         pit
                                                                 To effluent
                                                                    tank
              Fig.  6  Final sedimentation tank of Company K's process
                                      213

-------
     After passing through the degasser, the liquor is transferred
to the final sedimentation tank for the separation of the remaining
sludge from the liquor.   The final sedimentation tank is of the same
type as that used in the conventional activated sludge process, but
a scum collector as shown in Fig. 6 is provided for the removal of
scum.
                                214

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3.    EVALUATION METHOD

 1.1  PURPOSE OF DEVELOPMENT

           The conventional activated sludge process has been commonly used
      for municipal wastewater treatment in Japan.   This is because the
      conventional activated sludge process has a variety of advantages,
      although there is still room for improvements such as in the structure
      of the aeration tank, oxygen transfer rate, mixing method,  and so
      forth.
           On the other hand, there are many cases where the conditions of
      land utilization are too severe to obtain a large area for a sewage
      treatment plant or special efforts must be made to controling detri-
      mental effects on the surrounding environment.
           It was considered that the deep well biological process was
      capable of overcoming such disadvantages, particularly in the reduction
      of the required site area, the ease of applying countermeasures to
      odor and other environmental problems and probably in reduction of the
      aeration cost.
           On the other hand, difficulty in solid-liquid separation was ex-
      pected, and in addition, it seemed necessary to further examine con-
      struction methods, safety, and durability of the facilities.
           Therefore, the characteristic of this process have been investi-
      gated and further development of this technique is proposed.

 3.2  GOALS TO BE ACHIEVED

           The goals to be achieved by this process were set as follows:

           Subject:  The development of the deep well biological process
                     for sewage treatment.

      Goals to be Achieved

      (1)   To have a treatment capability of 1000 m3/day or more.

      (2)   To be able to meet legal requirements for the biochemical oxygen
           demand(BOD)  and suspended solids(SS) of the secondary effluent.
                                        215

-------
     (3)   To be simple in operation and maintenance.

     (4)   To be low in operation and maintenance costs.

     (5)   TO have simplicity in taking countermeasures against detrimental
          effects on the surrounding environment.

3.3  SCOPE OF EVALUATION

          The prerequisites for the sewage and sewage treatment facilities
     to be used for the evaluation of this technique  are as follows:

     (1)   The sewage used in the experiment shall be  ordinary sewage
          composed of domestic wastewater and institutional wastewater
          (from offices, hospitals, and other business facilities), and it
          shall be municipal sewage that can be treated and biodegraded by
          the conventional activated sludge process.

     (2)   The facilities in the treatment plant other than those within
          the scope of this evaluation shall be designed according to
          the "Sewerage Facilities Design Guide" and shall have the func-
          tions required by the legal regulations.

     (3)   The deep well biological process facilities shall be constructed
          with sufficient safety and accuracy.

          Under the above prerequisits, the evaluation was made within the
     range of the sewage treatment process from the inlet to the deep well
     aeration tank to the final sedimentation tank.

3.4  EXPERIMENTAL FACILITIES

          The evaluation was made based on the data of the experiments
     carried out by the applicants using experimental facilities installed
     in municipal sewage treatment plants.  When, the data was not sufficient,
     the evaluation committee required the applicants to conduct specific
     additional experiments.
          The dimensions of the main units of the experimental facilities
     are shown below.  The major mechanical equipments are  shown in Table 1.
                                    216

-------
Experimental facilities of Company I

  Deep well aeration tank:  Aeration tank with a diameter of 1 m,
                            a depth of 100 m, and an effective
                            capacity of 100 m   (including a head
                            tank) .
  Vacuum degasser:          Degassing tank with a diameter of 1 m,
                            a height of 13.6 m   (from the ground),
                            and a capacity of 6 m .
  Final sedimentation tank: Circular sedimentation tank with a
                            diameter of 12 m, and a depth of 3 m.

Experimental facilities of Company K

  Deep well aeration tank:  Aeration tank with a diameter of
                            0.8 m,  a depth of 100 m, and a
                            capacity of 57.5 m3  (including a
                            head tank).
  Floatation tank:          Floatation apparatus with a width of
                            4m, a length of 7.5m,  a depth of
                            3.5 m,  and an effective capacity of
                            84 m3.
  Degasser:                 Rectangular tank with a width of
                            1.5 m,  a depth of 4 m, and an ef-
                            fective capacity of 4 m3.
  Final sedimentation tank: Rectangular sedimentation tank with
                            a length of 10 m, a width of 4 m, a
                            depth of 3 m and an effective capacity
                            of 120 m3.
                             217

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Table 1-a  Specifications for major equipments of Company
           I's facilities (design treatment capacity:
           2400 m3/day)
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
Equipments
Influent pump
Compressor
Head tank
Deep well aeration
tank
Vacuum degasser
Vacuum pump
Return sludge pump
Sludge collector
of final sedimenta-
tion tank
Final sedimentation
tank
Scum tank
Scum pump
Effluent tank
Effluent pump
Specification
2.5m3/min * 12m x Hkw
250Nm3/hr x 7kg/cm2G x 35.9kW
1.5W x 6.0L x 4"
m mm
1.0^ x 100H
m m
1.0^ x 13. 6H
m m
0.49Nm3/min x 550mmHg x 2.2kW
2.5m3/min x lOm x ]_5kW
0.4kW
12* x 3H
m m
1.30 x l.0H
m m
O.lm3/min x 9m x 0.75kW
1.67* x i.97H
m m
2.5m3/min x i5m x Hkw
No. of
equipments
installed
2
1
1
1
1
2
1
1
1
1
1
1
1
                         218

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Table 1-b  Specifications for major equipments of Company
           K's process (design treatment capacity:
           1000 m3/day)
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Equipment
Deep well aeration
tank
Relay tank
Floatation tank
Degasser
Final sedimentation
tank
Sludge storage tank
Effluent tank
Influent pump
Re circulation pump
Sludge return pump
Effluent pump
Aeration blower
Degasser blower
Sludge collector
in floatation tank
Sludge collector
in final
sedimentation tank
Specification
0.8^ * 100H
m m
2W x 2.5L x 3"
m mm
4W x 7.5L x 3.5H
m m m
1.5W x !L x 4H
m m m
4W x 10L x 3"
m mm
1W x 4L x 2.4"
mm m
2<*x2H
m m
1.5m3/min x iQm x ?.5kW
8m3/min x 5.5m x I5kw
1.5m3/min x 20m x nkw
1.5m3/min x sm x 3.7kW
!Nm3/min x 0.5kg/cm2 x 3 . 7kW
Im3/min x 0.5kg/ cm2 x 3.7kW
0.4kW
0.4kW
No. of
equipments
installed
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
                        219

-------
3.5  EXPERIMENTAL METHOD

 3.5.1  Characteristics  of Influents

             The experimental facilities  were built into the existing
        sewage treatment plants.   The  properties  of the  corresponding
        drainage areas were as follows:

             Drainage area of the  STP  where  the experimental facilities  of
             Company  I was installed.
               Sewage drainage system:  Separate  system  with partially
                                       combined  system
               Population:
               Average  flow:
About 280,000
166,900 m /day
             Drainage  area  of  the STP where  the  experimental  facilities  of
             Company K was  installed.
               Sewage  drainage system:  Separate system
               Population:              About  10,000
               Average flow:            2,200  m  /day
       The properties of  influents are  shown  in Table  2.
           Table  2-a  Characteristics of  influent  of  facilities  of
                      Company  I
Item
Characteristics
of sewage
pH
SS (mg/£)
BOD (mg/&)
COD (mg/A)
Raw sewage
Influent to deep
well aeration tank*
Most of the sewage is made up of domestic wastewater,
but partially includes industrial wastewater.
Further, the supernatant from the nightsoil treatment
facilities is always discharged into the sewage.
7.1 ^ 7.4
125 ^ 142
105 ^ 152
95 ^ 127
7.7 (7.4 ^ 8.3)
126 (67 ^ 292)
99 (51 ^ 189)
69 (40 ^ 113)
   *Effluent  from primary  sedimentation tank.
                                   220

-------
            Table 2-b  Characteristics of influent of facilities of
                       Company K
Item
Characteristics
of sewage
pH
SS (mg/£)
BOD (mg/£)
COD (mg/£)
Raw sewage
Influent to deep
well aeration tank*
Domestic sewage
7.6 (7.4 ^ 7.6)
175 (163 'v 218)
159 (123 ^ 179)
107 (100 ^ 114)
7.4 (7.3 % 7.5)
120 (106 ^ 146)
92 (76 ^ 102)
64 (56 ^ 81)
             *Effluent from primary sedimentation tank


3.5.2  Experimental Conditions


            The experimental conditions are shown in Table 3, and the

       sampling stations for water quality analysis and parameters analyzed

       are shown in Table 4.
                                     221

-------
                                       Table 3-a  Experimental  conditions  for Company  I's process
ro
ro
(V)
Exp.
No.
D-l
D-2
D-3
D-4
D-5
D-6
E-l
E-2
E-3
E-4
E-5
F-1
F-2
S*
Experimental
period
1979. 4/6
04/11
1979. 4/15
0,4/22
1979. 4/23
05/18
1979. 8/13
08/23
1979. 8/24
08/30
1979. 8/31
0,9/5
1979. 10/11
MO/21
1979. 10/22
010/25
1979. 10/26
011/4
1979. 11/5
0.11/20
1979. 12/4
012/27
1980. 1/18
01/31
1980. 2/1
0-3/5
1980. 9/26
0-10/5
Flow
m /day
1320
2400
1840
1840
1520
1840
2400
3000
3600
2400
1840
1840
947%
1940
2240
Flow fluctuation
m3/hr
55 constant
100 constant
30 o, 100
30 o, 100
30 o 80
30 o, 100
100 constant
125 constant
150 constant
50 o, 150
30 0 100
30 o, 100
30 o 145
50 o, 130
Aeration
time, hr
1.8
1.0
1.00,3.3
1.003.3
1.303.3
1.00-3.3
1.0
0.8
0.67
0.670-2.0
1 . 003 . 3
1.003.3
0.69M.3
0.77-V2.0
Air supply Nm /hr
upf low
tube
50
50
50
50
50
50
50
50
50
50
50
50
50
50
down flow
tube
30
30
30
30
30
30
30
30
30
30
30
30
30
30
MLSS
mg/f.
4380
(4000-M630)
3560
(3310^3990)
3230
(224CK3940)
3570
(2880^4260)
3490
(3190-V37SO)
4020
(3500^4400)
1990
(1670V250)
1790
(1480^1970)
1760
(1580M980)
1490
(1230^1810)
2480
(1790^3430)
2830
(2260^3170)
2910
(1990%3620)
2260
(2030^2550)
Return
sludge
ratio
%
55
constant
60
constant
78
(600,200)
78
(60^200)
110
(88^230)
91
(70-^230)
15
constant
12
constant
10
constant
15
(100-30)
33
(25-V83)
39
(300-100)
78
(340-167)
21
(150-40)
BOD-SS
loading
kg/kg SS day
0.27
(0.2100.33)
0.74
(0.620O.91)
0.94
(0.690.1.28)
0.54
(0.3400.89)
0.43
(0.300O.48)
0.44
(0. 290O. 55)
1.05
(0.67M.47)
1.49
(1.260.1.91)
1.78
(1.510-2.09)
2.21
(1.640-3.13)
1.14
(0.440-1.89)
1.12
(0.830-1.42)
1.39
(0. 7102.06)
0.98
(0.6501.33)
BOD volume
loading
kg/m3 day
1.19
(0.940-1.89)
2.64
(2. 2003.19)
2.95
(2.4704.44)
2.04
(1.3702.81)
1.49
(1.0601.75)
1.77
(1.2202.18)
2.08
(1.3402.74)
2.60
(2.430,2.82)
3.14
(2.3803.85)
3.24
(2.4803.85)
2.68
(1.4203.60)
3.02
(2.2303.60)
3.96
(2.4405.90)
2.19
(1.4102.93)
                                   •Performance confirmation exp.

-------
                               Table 3-b  Experimental conditions  for Company K's process
Exp.
No.
Run
1-1*1
2
3
4
5
6
RUn *2
IV ^
Experimental
period
1980
3/1VJ/21
5/10-V/30
6/4^6/14
3/22-V3/23
6/15^/25
12/1^12/20
10/11MO/23
Flow
ms/day
1000
600
1000
1000
1000
1060
i
1000
Flow
fluctuation
41.7 m3/"r
constant
25 mVhr
constant
41.7 ras/hr
constant
12.4^81.3
m3/hr
13.5^88.1
m'/hr
24.0^58
m'/hr
22.3^59.5
m3/hr
Aeration
time
(hr)
1.38
2.3
1.38
1.38
0.71^4.64
1.38
0.65M.26
1.30
0.99^2.40
1.38
0.97^2.58
Air supply
Nm3/hr
30
18
18
30
18
12
12
MLSS
(mg/£)
2820
1440^3890
3060
1810^3770
3020
2120M040
3600
3760
3100^3950
3940
3600^4100
3240
1710^3970
Return
sludge
ratio
%
65
61^95
44
34^62
50
34'^65
75^242
42
34^59
44
38^48
50
47^54
BOD-SS
loading
kg/kg SS day
0.41
0.29^.87
0.24
0.11^.54
0.56
0.31VL.1
0.42
0.53
0.24M).71
0.43
0.37V). 50
0.45
0.35^). 83
BOD volume
loading
kg/m3 day
1.2
0.76^1.6
0.70
0.3 4^1 .3
1.7
1 . 0-V2 . 4
1.5
2.0
0 . 9^2 . 4
1.7
1.4^1.9
1.45
1.3^1.6
PO
ro
CO
        *1:  Applicant's  experiment
        *2:  Performance  confirmation  experiment

-------
Table 4-a  Parameters analyzed in the experiment of Company I's
           process

Parameters
>i
4J
•rH
r-H
<0
3
O1
S-<
0)
(0
<1J
Oi
HD
p
H
CO
pH
SS
BOD
CODMn
CODcr
TOG
Kj-N
NH+-N
NO~-N
NO~-N
T-P
»r
M-alkalinity
Transparency
Temperature
DO
SS
vss
sv
SVI
ssv
Influent
T
O
O
O
0
O

0
O


O

O
0
0
O

O



S


O
O
0
0


O
0

O









Effluent
T
O
O
O
O
O

O
O


O

O
0
O
0





S


O
O
O
0


O
0

0









Head
tank
















O
O
O



Effluent
from
vacuum
degasser

















/

O
O
0
Return
s ludge



•













O:'
O



Excess
sludge






















Frequency

Once/day
Once /day
Once /day
Once/day
2-3
times/week
Once/day
Once/week
Once/week
Once/week
Once/week
Once/week
*Once/day
*Once/day
Once/day
Twice/day
Twice/day
Once /day
Once/day
Once/day
Once /day
Once/day
     T:  Total
     S;  Soluble
     *:  Additional parameters  on  performance  confirmation experiment
                             224

-------
                      Table  4-b  Parameters analyzed  in  the  experiment of Company K's process
Parameters
2 Water quality
tn
T3
3
i-H
pH
SS
BOD
CODMn
TOC
Kj-N
NH+-N
NO~-N
NO~-N
T-P
PO^-P
M-alkalinity
Transparency
Temperature
DO
SS
VS
Influent
(effluent
from primary
sedimenta-
tion tank)
Total Soluble
O
0
O 0
O 0
0
O
O
0
0
O
O
O

0



Effluent
Total Soluble
O
0
0 0
0 O
O
0
O
O
O
O
O
O
0
0
O


Mixed
liquor
in
aeration
tank
Total

O











O
O


Return
sludge















O
O
Excess
sludge















0
0
Settled
sludge
withdrawn
from
floation
tank















O

Floated
sludge
in
floation
tank















O

Sludge
withdrawn
from
final
sedimenta-
tion















O

Frequency
times /day
3
1
1
1
1
1
1
1
1
1
1
1
1
3
3
1
1
ro
en

-------
     For the sampling of the influent, effluent, and return sludge,
automatic samplers were used, and respective 24-hour samples were
analyzed as the flow proportional composite samples.  The analyti-
cal methods used were the glass-fiber filtration method specified
in JIS K 0102 for SS, and other methods described in "Analytical
Methods for Sewage Water Quality" compiled by the Japan Sewage Work
Association.
     The sewage flow, return sludge, and excess sludge withdrawal
were measured by electromagnetic flowmeters.
     As to the feed flow rate to the experimental facilities, two
types of flow patterns were employed, that is, a fixed flow rate,
and a fluctuating flow1 rate that was proportional to the influent
rate of the corresponding treatment plant.  This fluctuation pattern
in flow rate is shown in Pig. 7.
                           226

-------
100-
80 -
68-
40 -
20-

























20 C
i i i i i i ' ' i i i i
4 8 12 16 20 0 4 8 12 16 20 0
                                  Time (hr)
h
160 -
140 -
120 .
100
80 -
60 -
40 -
20 -
2











ii 'iii
004 8 12 16 20











i i i i i i i
0 4 8 12 16 20 0
                                  Time  (hr)
           Fig.  7-a  Flow fluctuation pattern (To be adjusted manually)
                    for  Company  I's  process
                                       227

-------
       100
        80-
        60-
     g  40
     u,
        20-
                        Air injected: 18 Nra3/hr
                        Circulation
                        rate:        3.25 m'/min
                        Average flow: 46.8 m3/nr
                                  (1100 mVday)
            18:00
            6/19
0:00
6/20
	1	
   6:00

 Time  (hr)
	1	
 12:00
             18:00
         Fig. 7-b  Flow fluctuation pattern for Company K's process

            As for the experiment No.  E-4 of Company I, the flow  rate
       fluctuation pattern  often found in a typical small scale treatment
       plant was employed as  shown in  Fig. 7-a.
            The return sludge rate was determined so that the MLSS  concen-
       tration in the head  tank  or relay tank reached the predetermined
       value.
            The vacuum degasser  was controlled so that the vacuum at the
       top of the tank was  maintained  at a level of 0.3 atm abs.  For  the
       recirculation of the mixed liquor with a pump, the circulation  was
       conducted at a circulation rate of 3.7 m3/min and at a downflow
       velocity of 0.9 m/sec.

3.5.3  Performance Confirmation  Experiment

            The performance confirmation experiment for confirming  prac-
       ticability was conducted  using  the same experimental facilities as
       that in other experiments.   The water quality of the influent during
       the performance confirmation experiment is shown in Table  5, and
                                    228

-------
the experimental conditions are shown in Table 6.   Further, the

fluctuation pattern of the flow rate is shown in Fig. 8.


   Table 5-a  Water quality of the influent to the aeration
              tank, Company I's process
Parameter
pH
SS (mg/£)
BOD (mg/£)
COD (mg/£)
Influent
7.63
112
97.9
71.0
water quality
(7.51^7.71)
(8Cn/L62)
(63VL31)
(55^88)
   Table 5-b  Water quality of the influent to the aeration
              tank, Company K's process
Parameter
pH
SS (mg/£)
BOD (mg/£)
COD (ing/JO
Influent
7.1
77
80.8
43.0
water quality
(6.8-V7.8)
{50VL14)
(72.1^0.1)
(36.5^48.5)
   Table 6-a  Experimental conditions for Company I's process
Exp.
No.
S
ExperiMital
period
1980. 9/26
"HO/5
Flow
•'/day
2340
Flow £luctua~
tier «'/hr
50^.130
Aeration tinw

-------
    140-

    120-


"£  100_

en
-   80-




     40-
                130
         100
                             100
                                                50
                                                            100
                                 1     I    \
         8    10  12   14   16   18  20   22    24    2     46    8

                            Time  (hr)


              Fig.  8-a  Flow  fluctuation pattern for performance
                        confirmation test of Company I
    60
^   40 -
    20 -
Cu
                  58.0
          44,7
                                                  22.3
       8        12        16        20        0         4

                           Time  (hr)

            Fig. 8-b  Flow fluctuation pattern for performance
                      confirmation test of Company K
                                   230

-------
4.   EVALUATION OF FACILITIES

 4.1  OPERATING SIMPLICITY

           This process is a modification of the conventional  activated
      sludge process,  and it is no more difficult to  operate than  the  con-
      ventional method.  The operation  procedure and  inspection  method in
      this process is  determined by each applicant.

 4.2  DURABILITY

           The material used for the deep well aeration  tank is  steel  or
      reinforced concrete.  The steel will cause no serious problem as long
      as the corrosion rate over its lifetime is taken into consideration in
      the design,  and  anti-corrosion paint is applied to the draft portion  of
      the tank.
           The reinforced concrete also couses no problem, as  the  conditions
      for the concrete are not  much different from those for other similar
      structures.
           Japan is subject to  frequent earthquakes which often  cause  great
      damage to structures.   Therefore, earthquake proof design  for the deep
      well aeration tank was investigated using kinetic  analysis.   It  was
      found that there would be no difficulty in designing earthquake  proof
      structures for the deep well aeration tank.

 4.3  SAFETY

           The facilities except for the aeration tank and the vacuum
      degasser are the same as  those used in the conventional  method.   It is
      possible to  secure safety in operation of the aeration tank  by taking
      preventive measures, such as installing fences  around the  tank to
      prevent people falling in.   Safety of the degasser can be  assured by
      designing the structure according to the regulations described in the
      "Labor Safety and Sanitation Law".

 4.4  INFLUENCE ON SURROUNDING  ENVIRONMENT

           It is possible to control noise pollution  due to the  compressor,
      pump,  and other  apparatus by taking ordinary preventive  measures.
                                      231

-------
          Deodorization is not difficult as the area open to the air and
     the air volume in this process are less than those in the conventional
     method, and the odor concentration is of almost the same degree as
     in the conventional method.   Prevention of aerosol dispersion is easy as
     the area open to the air is  small.

4.5  CONSTRUCTION METHOD

          Each applicant has established their own construction method.
     Although, previously there were no municipal wastewater treatment plants
     employing this process in Japan, several industrial wastewater treat-
     ment plants using this process have been already constructed.   Judging
     from these experiences, there will be no problem in the construction of
     actual municipal wastewater  treatment plants.
                                    232

-------
5.    EVALUATION OF TREATMENT PERFORMANCE

 5.1  DESIGN CAPACITY

           The  design flow of the  experimental  facilities  of Company I is
      2,400 m /day.   In  the performance  confirmation  experiment conducted
      under the condition that the daily average  flow was  2,240 m3/day
      (maximum  hourly rate: 130 m3/hr, minimum  hourly rate:  50 m3/hr), the
      effluent  water quality met the  legal  standards  in  which BOD was  20 mg/1
      and SS was 70  mg/1 or less.   Accordingly, the goal of  the effluent
      water quality  was  achieved.
           The  design flow of the  experimental  facilities  of Company K is
      1,000 m3/day.   The performance  confirmation experiment conducted at a
      flow rate of 1,000 m /day (maximum hourly rate:  58 ms/day,  minimum
      hourly rate: 22.3  m3/day)  showed that the effluent quality could meet
      the standards.   Therefore, it can  be  said that  the goal for the  ef-
      fluent water quality was accomplished by plants  with capacities
      set as a  goal.

 5.2   AERATION  PERFORMANCE

           Fig.  9  shows  the vertical  distribution of dissolved oxygen  (DO)
      in  the downflow tube of the  aeration  tank when  clear water  is  used.
                                    233

-------
ro
CO
        VD


        S»
~ D
n  o

rt>  QJ
Qf  P*
5  w

*z

%&
fl>  C
h^  ("t°

0)  O

3s
fl>  P-
H  D

tTo.
n>  (D
3  n>
rt >O

~ s:
   (D
        D.
        (D
        rt

        S
                                                          Water depth  in downflow tube  (m)
                        O
                        o
00
o
                8

                s"
                    »0

                    O
                    S
                                                           o

                                                          _1_
                       o

                      _L_
 O

_J_
                                                                                                   U)

                                                                                                   0
                                                                                                              0

                                                                                                               1
                                                                                             H-
                                                                                             3
                                              O
                                              ft
                                              p-


                                              §


                                              V
                                              0
                                              w
                                              H-
 O

_J_
 o
J
                                                                                  -G
                                            S <
                                            BJ tt>

                                            rt M  G
                                            (DOW
                                            ^ O  hh
                                              P-  M
                                            rt rt  o
                                            2 ^  «
                                              P- rt


                                             .3&
                                            B) rt ro
                                            rt d
                                            c 5-
                                            M n>
                                            (D
Do
                                                                                                                             (D
                                                                             NJ O Ul NJ
                                                                             u> •  o in
                                                                                                                             n
          M
          X
        > 13
        P- (0
        K h
          P-
     s;  P- 3
     g  D (D

     ^^- s
     M (D rt

     i  R^


     gS 8
     &   3
     n>  i-( a
        Q) P-
        rt rt
        (D P-


          03
                                                                                                                               "II
                                                                                                                               3  CO  U*



                                                                                                                               W 3s 3*
         o
         l-h
         O

-------
g
rH
M-l
T)
c
•H

-U
ft
(1)
0)
4-)
10
      0

     20
-?    40
0)
•§
-P
 60
 80-
100-
                       Liquid level in relay tank
       Experimental conditions
         Air injection
         rate:          12 Nm3/hr
         Velocity in
         tube:          1.0 m/sec
         Water
         temperature:   21.9°C
                10
                     —r—
                      20
	1—
       30
 DO (mg/1)
                                             40
—[—
 50
                                                             60
   Fig. 9-b  DO distribution in deep well aeration tank of Company K
             (clean water experiment)
      According to the distribution of DO, the oxygen transfer efficiency
 is 71% for Company I and 79% for Company K.  As to the air volume for
 aeration, in Company I's experimental plant, the air was injected into
 the downflow tube at 30 Nm3/hr, and the ratio of removed BOD to oxygen
 by this air was 1:0.8.  Additional air was injected into the upflow
 tube at 50 Nm3/hr in order to maintain stable recirculation of the
 liquor.  Fig.  10-a shows the time variations of DO in the head tank,
 and BOD and SS of the effluent during the performance confirmation
 experiment.  During 24 hours, DO in the head tank was 4 mg/1 or more,
 which means sufficient aeration was accomplished.
                                  235

-------
     140  .


•£   120


"^   100  -


 g    80  .
i-4

fa    60  -


      40  .


      10


       8

cH
\     6



8     4

       2
                                            ^   i    i    i
 Cn
M
CO
     180  ,


     160  -


     140  -


     120  .


     100  -

      80


      60  .


      40  .


      20
                                         . Influent


                                       .  o Effluent
Standard for effluent BOD
                                                 Standard for
                                                 effluent SS
                                                                • Influent

                                                                o Effluent
           55.9.30                             55.10.1
             8   10  12  14  16  18  20  22  24  2   4    6
                              , Time (hr) '
       Fig. 10-a  Variation of water  quality (Performance confirmation
                  experiment  of Company I's process)

                                     236

-------
     60 H
 ~    40-




m

 _g



 3    20-
i
4J
  0




  4-



  3-




  2-




  1




  0




120-









100-








 80-
 3    60 -\
      20
                                                   Influent
                                                • Effluent standard
                                               Effluent
                        Influent
                                                    Effluent standard
             10/19

                9:00
                                  I        I	

                                       10/00

                                 21:00   1:00
                  13:00   17:00   21:00   1:00   5:00


Pig. 10-b  Variation of water quality  (Performance confirmation

           experiment of Company K's process)


                             237

-------
In the performance confirmation experiment of Company K, the air supply
was kept at 12 Nm /hr based on the results of the experiments conducted
by the applicant.  The time variations of similar parameters are shown
in Fig. 10-b.   During 24 hours, DO in the relay tank was 2 mg/1 or more,
and the aeration was sufficient for the operation.
     The vertical profile of DO in the downflow tube is shown in Fig. 11.
From this DO distribution, it can be seen that sufficient DO concentra-
tion was maintained and an aerobic condition was provided throughout the
tank.
                                   238

-------
0)
•§
-P
a
r-H
c
•H
a
-s
      0-
     10-
     20-
     30-
40-
     50-
60-
     70-
     80-
     90-
    100
                                         Date of measurement
                                         S55.9.26  S.55.9.27
                        Symbol
                   Air injection rate
                     Upflow tube
                            (NmVnr)
                     Downflow tube
                            (Nm3/hr)
                   Velocity in downflow
                   tube     (in/sec)
                   BOD-SS loading
                          (kg/kg SS day)
                   MLSS
(mg/1)
                   Water temperature
                   in head tank
                   DO in head tank
                             (mg/1)
 50

 30

0.75

1.04

2030

24.5


 7.8
 50

 30

0.75

0.88

2410

23.6


 7.5
        0    2    4    6    8   10
               DO (mg/1)


      Fig.  11-a  DO distribution in deep well aeration  tank  of
                 Company I (regular operation)
                               235

-------
0
20-
_
'i
~ 40 -
i
4J
rH
c 60 "
c
•H
£ 80-
0)
T)

0)
4J
10
s 100-
(

Liquid level in relay
tank
Date of measurement Oct. 17
Air injection rate
(Nm3/hr)
Velocity in downflow
tube (m/sec)
BOD-SS loading n Q
. _ ,_ . u » j _/
(kg/kg SS day)
MLSS
Water
relay
DO in
3

< )
C
1 1 I 1
D 10 20

(mg/1) 3800
temperature in 22 0
tank (°C)
relay tank 3 Q
(mg/1)



1 ' | ' 1 '
30 40 50 6
DO (mg/1)
Fig. 11-b  DO distribution in deep well aeration tank of
           Company K (regular operation)
                         240

-------
          As for the microorganisms in the activated sludge of the deep well
     biological process,  Ciliata such as Vorticella, Opercularia and Aspidisca
     were predominant,  and higher organisms such as Rotaria and Phabdolaimus
     were also present.  The biota in the deep well biological process does
     not differ greatly from that in the conventional method.

5.3  WATER-QUALITY IMPROVEMENT PERFORMANCE

 5.3.1  BOD and SS

        (1)   Effect of  BOD Loading

                  The relationship between BOD volume loading and effluent
             BOD is shown in Fig.  12, and the relationship between BOD volume
             loading and  BOD removal is shown in Fig. 13.
                                       241

-------





30 -
20 -


P
IT
3 10 -
Q
O .,
ffl 7 .
c
S 5-
r-l
W
1
• D series
o E series
A F series
D Performance
confirmation


o
Q . o A
o

•
• •
•




0.1
          0.7   1         2345

BOD volume loading (kg/m  day)
   Fig. 12-a  BOD volume loading and effluent BOD in Company  I's
              process
                             242

-------
    50
    20 -
g   10
Q
O
a
     5 -
     2 -
                                              ••:•«
                                 • •   %
                                           o *  •   •
                                         • o>o*o   •   .
                                         CD
                                 • Applicant's experiment

                                 o Performance confirma-
                                   tion exp.
0.1      0.2         0.5
                                                                   10
                     BOD volume loading (kg/m  day)
       Fig. 12-b  BOD volume  loading  and  effluent  BOD in  Company K's

                  process

^

rH
ra
1
M
Q
0

100
90


80
70




-
.A A
0 o «o A
0 0
o
• D series
o E series
A F series
: a Performance
confirmation exp.
                      BOD volume  loading  (kg/m3  day)


       Fig.  13-a  BOD volume loading and BOD removal in Company I's

                  process
                               243

-------
100
 90-
 80-
§    70^
 60-
                                    o o     •. ••
                                     . CP   *:..
                                            • Applicant1  experiment
                                             Performance confirmation
                                             exp.
               0.5
                               1.0
1.5
2.0
2.5
                    BOD volume  loading  (kg/m  day)
3.0
    Fig. 13-b  BOD volume loading and BOD removal in Company K's process

                In this experiment, BOD volume loading was set at 1.3 -
           1.6 kg/m3 day and 1.2 - 4.0 kg/m3 day for the facilities of
           Companies K and I, respectively.  BOD-SS loading was set at
           0.4 - 0.8 kgAg SS day for K plant and at 0.3 - 2.2 kg/kg SS
           day for I plant.  In these ranges of loading, both facilities
           could meet the goal of the development on effluent quality.
           Therefore, in the deep well biological process, as compared
           with the conventional method (BOD volume loading: 0.3 - 0.8
           kg/m  day), high BOD volume loading and almost the same or
           more BOD-SS loading than that in the conventional method (BOD-
           SS loading: 0.2 - 0.4 kg/kg SS day) can be applied to the plant.
           The relationship between BOD-SS loading and effluent BOD is
           shown in Fig. 14.
                                   244

-------
8
CQ
-P

-------
    50
8
M
W
    20-
    10-
     5H
     2-
                                   00
                                    §
. Applicant's experiment
o Performance confirmation
 exp.
      0.05     0.1      0.2        0.5      1.0       2.0
                     BOD-SS loading  tkg/kg SS day)
                             5.0
       Fig. 14-b  BOD-SS loading and effluent BOD in Company K's
                  process

     (2)   Removal of SS

               Table 7 shows the overflow rate, weir loading, and ef-
          fluent SS in this experiment.   In any case, effluent SS was
          within the standard,  and there was no problem in applying
          overflow rate and weir loading equivalent to those for a
          ordinary secondary sedimentation tank.
                                246

-------
Table 7-a  Overflow rate and weir loading VS  effluent  SS,  Company
           I's process
Exp.
No.
D-l
2
3
4
5
6
E-l
2
3
4
5
F-l
2
S
Overflow rate
(m3/m2 day)
Average
13.2
24.0
18.4
18.4
15.2
18.4
24.0
30.0
36.0
24.0
18.4
18.4
16.0
22.4
Range
Constant
Constant
7.20-24.0
7.20-24.0
7 . 20-19 . 2
7.20-19.2
Constant
Constant
Constant
12 . 00-36 . 0
7.20-24.0
7.20-24.0
7.20-34.8
12.00-31.2
Weir loading
(m /m day)
Average
37.5
(Constant)
68.2
(Constant)
52.3
52.3
43.2
52.3
68.2
(Constant)
85.2
(Constant)
102
(Constant)
68.2
52.3
52.3
45.5
63.6
Maximum
-
-
68.2
68.2
54.5
68.2
-
-
-
102
68.2
68.2
98.9
88.6
Effluent SS
(mg/1)
Average
24.3
28.0
23.7
15.9
12.1
16.0
9.0
12.0
17.0
16.9
20.0
15.4
16.4
15.2
Range
20^28
19^36
7^37
10^23
lO'Vie
14^18
60-19
10^17
irV24
9^23
13^28
100,25
100,23
110-21
                              247

-------
Table 7-b  Overflow rate VS effluent SS, Company K's process
^^^--~^Run No.
Overflow
rate
(m3/m2 day)
Weir
loading
(m3/m day)
Average
Peak
Average
Peak
Effluent SS
(mg/1)
Run II-l
25
27
250
270
34
(24M5)
Run I 1-2
15
18
150
180
25
(16^34)
Run I 1-3
25
30
250
300
30
(20-MO)
Run II-5
25
53
250
530
33
(23^43)
Run I 1-6
26.5
35
106
139
18
(12^26)
Performance
confirmation
experiment
25
35
100
140
18
(11^25)
 (3)   Stability in Treatment

           The daily variations in BOD and SS are shown in Fig. 15.
      The flow rate, BOD and SS of the feed fluctuated considerably,
      but the effluent quality remained fairly stable.
                              248

-------
    140 -


    120 -


_   100 -
tH
\
e    so -

Q
«    60 -


     40 -


     20 -
                               -o——o-
                                                      •  Influent
                                                      o  Effluent
                                                      x  Third-party
                                                         analysis
    120 -


^  100 -
rH

J   80 -


     60 •


     40 -


     20 -
                                                      • Influent
                                                      oEffluent
                                                      XThird-partv
                                                        analysis
                               \     I
9/26  27   28  29    30   10/1  2    3
Fig. 15-a  Daily variation in BOD and SS (performance  confirmation
           experiment  of Company I's process)
                             249

-------
                                                      X ... Third party-
                                                           analyzed BOD
                                                              Influent BOD
E    50-
§
pa
                                                            Effluent BOD
                                                   -or
                                                       -o-
    100-
                                                     X... Third party-
                                                           analyzed SS
                                                             Influent SS
                                                            Effluent SS
                                                             I     I
             I     |     I     I    I     I     I     I     |~    (

           10/11 12   13   14    15    16   17   18   19   20   21   22   23
          Fig. 15-b  Daily variation data (performance confirmation
                     experiment of Canpany K's process)
                                    250

-------
     Fig. 16 shows the water quality data in winter when the
performance of the activated sludge process is liable to be
lowerd.  Although the loading varied considerably, the effluent
quality also remained relatively stable.
                           251

-------
en
ro
       §
       M
       c
       M
       Q
       O
       m
m
M
       U)
       ui
       (A
      100-


       80-


       60-


       40



      300-


      200-


      100-
                   Hourly mean

                   76.7 (30-100 m3/hr variable

                         flow)
Each plot  is  based on hourly mean  (Max.  95-145,

Min. 30 m3/hr variable flow)
       30


       20



       10-
      300


  C^  200


  ~  100






       30


  ~   20-
                                                             30


                                                             -20


                                                             10
                                                                                                                  •5 o
                                                                                                                         £ 5
                                                                                                                         M 4-1
                                                                                                                         V
                                                                                                                         ft -O
                                                                                                                         E ft]
                                                                                                                         0) 111
                                                                                                                         E-i .C
10:
1980

1 1
1/18 20
U. 	
1 it '
25 . 30 2/1 5
.. ., , , .-.-.— J u* -
i i I
10 15 20
25 3/1 5
                                          Winter experimental data of Company  T's  process

-------
    1200
    1100-
    1000-
                                                          Influent
fc,
                    Water
                    temper-
                    ature
                                                              -13
                                                              r!2
                                                              L10
                                                                   0)
                                                                   4J
                                                                     L)
                                      0) X


                                      •P -P
                                      (0

                                      0) nJ

                                        Q)
     100-
                       Influent BOD

                         (mg/1)
§    5°i
CQ
                               Effluent BOD
                             ^standard
                        Effluent BOD
    100-
                                                       Influent SS
                                                            Effluent SS
                                                            standard
     50-
                                                       Effluent SS
      1980 12/1
 I

10
 I

20
          Fig. 16-b  Winter experimental  data of  Company K's process
                                    253

-------
5.3.2  Transparency of Effluent
            The transparency of the effluent during the  experiment is
       shown in Table 8.   It was rather lower than  the transparency of  the
       effluent in the conventional activated sludge process.

            Table 8-a  Transparency of  effluent,  Company I's process
Exp . No .
D-l
2
3
4
5
6
E-l
2
3
4
5
F-l
• 2
S
Effluent transparency (cm)
24.5 (21.6^27.0)
18.9 (15.0^26.0)
21.4 (14.5^39.0)
28.4 (19.5^40.5)
34.1 (26. 0^44.0)
25.1 (20.0^27.0)
38.9 (26.0^50.0)
35.3 (28.0M1.5)
25.8 (16.CA41.0)
23.3 (17.0M5.0)
23.3 (16.0M3.0)
23.5 (19.5^32.0)
23.4 (17.5^29.3)
25.4 (22.8^28.2)
            Table 8-b  Transparency of effluent, Company K's process
Run No.

Transparency
(cm)
II-l

20
(19^21)
II-2

22
(20^24)
II-3

21
(19^22)
II-5

20
(18^21)
II-6

23
(20^26)
Performance
confirmation
exp.
24
(23^26)
                                    254

-------
5.3.3  Others
            The results of the analysis for nitrogen,  phosphate,  and COD
       (Mn method)  in the influent and effluent during the experiment are
       shown in Table 9.
                                   255

-------
(S3
O1
Performance confirma-
tion experiment
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-------
                            Table 9-b  Water quality of influent and effluent, Company K's process
Parameters
Applicant's
experiment
(Run II-2
Constant flow)
Applicant's
experiment
(Run II-5
Variable flow)
Performance
confirmation
experiment
(Run IV)
Influent
Effluent
Influent
Effluent
Influent
Effluent
Water
temperature
<°C>
23.2
23.3
24.3
24.4
22.5
22.3
1
CODMn
(mg/1)
55.7
(50^61.4)
21.0
(18.1^23.9)
58.7
(55.5%61.9)
20.5
(19.0^22.0)
43.0
(39.4^6.6)
14.1
(12.2M6.0)
Kj-N
(mg/1)
35.1
(32.1^38.1)
17.9
(14.0^21.9)
34.4
(32.9^-38.9)
24.1
(23.1^.25.1)
29.3
(28.2^30.4)
19.3
(18.6^20.0)
NH*-N
4
(mg/1)
18.7
(17.2^20.2)
7.31
(3.68^10.9)
27.8
(23.7-X-31.9)
22.0
(20.9^29.1)
20.0
(19.2^20.8)
17.9
(17.3M8.5)
NO~-N
(mg/1)
0.02
(O.OM>.05)
1.01
(0.35^1.67)
tr
0.30
(0.22V). 38)
tr
0.24
(0.16V). 32)
NO~-N
(mg/1)
0.66
(0.29-V.1.03)
5.81
(1.59^10.0)
tr
1.5
(1.2M.8)
tr
1.7
(1.2^2.2)
T-P
(mg/1)
7.44
(6.7-^8.2)
4.53
(3.9^5.16)
7.4
(6.9M.9)
5.3
(4.9^.7)
5.3
(4.5^.1)
3.73
(3.27^.19)
PO^'-N
4
(mg/1)
5.42
(4.4VS.1)
3.90
(3.3M.4)
5.3
(4.4-^6.2)
4.3
(3.9^.9)
3.9
(3.4M.4)
3.2
(2.7^3.7)
ro
en

-------
5.4  SOLID-LIQUID SEPARATABILITY

          The mixed liquor from the deep well aeration tank, as compared
     with that in the conventional activated sludge process, contains a great
     quantity of supersaturated dissolved gas and fine bubbles.   Accordingly,
     the solid-liquid system of Company I has a vacuum degasser between the
     aeration tank and the final sedimentation tanks.   The installation of a
     vacuum degasser, makes it possible to employ a final sedimentation tank
     of ordinary design to separate solids from the mixed liquor.   The re-
     sults of the measurement for SVI and sludge setting velocity of the
     degassed sludge are shown in Table 10-a.
           Table 10-a  Sludge settlability,  Company I's process
Run No.
D-l
2
3
4
5
6
E-l
2
3
4
5
F-l
2
MLSS
(g/D
4.4
3.6
3.2
3.6
3.5
4.0
2.0
1.8
1.8
1.5
2.5
2.8
2.9
Return
sludge cone.
(g/D
12.9
9.6
8.6
8.9
8.2
9.2
15.8
15.2
16.6
14.2
11.6
11.4
9.7
SVI

128
109
177
134
80
73
122
93
81
95
126
121
115
SSV
(ml/g)
-
84
93
73
54
54
92
70
57
64
78
82
87
Settling
velocity
(m/hr)
-
1.9
1.7
2.2
2.9
2.5
2.5
3.5
3.6
3.6
2.3
2.2
1.9
                                   258

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     The solid separation system of Company K consists of a floatation
tank, degasser and final sedimentation tank.

(1)   Floatation tank

          Table 10-b shows the results of the operation of the floata-
     tion tank.  Fig.  17 shows the relationship between effluent SS and
     the overflow rate in the floatation tank, and Fig. 18 shows the
     relationship between effluent SS and the solid loading.
     The floated sludge had a high solid concentration at 13,300 mg/1
     on the average, and the SS removal was about
   Table 10-b  Sludge settlability (performance confirmation
               experiment), Company K's process
Parameter
Operating conditions
*Flow (m3/day)
MLSS (mg/1)
Overflow rate
(m3/m2 day)
Settling time
(hr)
Solid loading
(kg SS/m2 day)
SS in floatation tank
effluent (mg/1)
Floated sludge concen-
tration (mg/1)
SS in final sedimentation
tank effluent (mg/1)
Daily average
1558VL740
3330V3970
56^62 . 1
1 . 16VL . 3
185^231
Hourly maximum
1900^1958
-
67 . 9^,69 . 9
1.02M..06
-
Hourly minimum
1044^1238
-
37.3^44.2
1.63VL.93
-
56^8 (Average 78)
10650^15600 (Average 13300)
6^29 (Average 18)
  * Flow (m /day)  includes return sludge.
                               259

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a
0)
M-l
o
•rH
4J
nj
4J
rfl
O
H
M-i

C
•H

W
W
    200 -
    100 -
•Applicant's  experiment

° Performance  confirmation
 exp.
                        o  •
                        o
                      o  o

                      o °0
                —r—

                 30
            40
—r—

 50
60
—i—

 70
80
                      Overflow rate  (m3/m2  day)
      Fig.  17  Overflow rate and  SS  in floatation tank effluent of
               Company K's process
                                 260

-------
    250
    200 -
                    • Applicant's experiment

                   o Performance confirmation
                     exp.
 c

 3   150
rH
M-l
1-1
 0)
 a
 a
 o
•H
-p
 (d
4J
 id
 0
H
4-1
    100 -
o
 o
 o
    8
•H
W
W
     50-
                               100
 200
                                                                               300
                               Solid loading (kg/m  day)
            Fig. 18  Solid loading  and SS in floatation tank effluent
                                       261

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     The characteristics of the sludge in the deep well aeration
tank is shown in Table 11, and the floatation curve of the sludge
in the floatation tank is shown in Fig. 19.  The sludge floating
velocity was found to be 7.8 - 16 m/hr.  Therefore, considering
the high floating velocity together with the results of the
solid-liquid separatability shown in Table 10-b, it is concluded
that a high concentrated sludge can be obtained in a short period
of time with this floatation system.
     Table 11  Sludge characteristics in aeration tank of
               Company K's process
Parameter
MLSS (mg/1)
SVI
Settling velocity
(m/hr)
Performance
confirmation exp.
(Run IV)
3330^3970
67
7 . 8^16
Applicant 's
experiment
(Run II-5)
3760
66
4 . 4^12
                              262

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CO
    50
  100
Cylinder used for test: 2000 * 1000H

  .7.8 m/hr
  o 14.0
  * 16.4
  A 13.1
  A 12.0
                             10                      20

                              Floatation time  (min)
                                         30
                         Fig.  19   Floatation  curve  of  mixed liquor

        (2)   Final  sedimentation  tank

                 The  relationship between  the  overflow  rate or the flow rate
             and SS in the final  sedimentation  tank effluent is shown in
             Fig. 20,  and the  relationship  between  the weir loading and ef-
             fluent BOD  and  SS is shown  in  Fig.  21.
                                      263

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80

60 -
40 -
20 -
                                              . Applicant's
                                                experiment
                                              0 Performance
                                                confirmation exp.
                                                   o  ,
                                                    o*
                                                    o5
                      10
          15
          20
          25
                      Overflow rate (m3/m2 day)
          30
                                                                     35
            200
400
600
800
1000     1200
1400
                             Flow  (m /day)
    Fig.  20  Overflow rate and flow VS SS in final sedimentation
             tank effluent. Company K's process
                                264

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    40-
    30-
 tn



 8
 M  20-
 4J
 C
 0)
 3
w
    10-
                • Applicant's experiment

                o Performance confirmation
                  exp.
                                             t  '

                                                •  •  •'
                0*0
 o-


60-





50-
                 • Applicant's experiment

                  Performance
                  confirmation exp.
    40-
4J
C
    30-
W
    20-
    10-
                o
                o
               100
                                   200
                            Weir loading (m /m day)
300
           Fig. 21  Weir loading VS BOD and  SS  in  final sedimentation
                    tank effluent. Gempany K's  process
                                    265

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        In the experiment with the weir loading of 100 - 110 m /m-
   day,  effluent BOD,  SS and transparency were 11.3 mg/1, 18 mg/1
   and 24 cm on the average, respectively.  The settling curve of
   the sludge in the final sedimentation tank is shown in Pig. 22.
   Although almost all of SS in the effluent from the floatation tank
   settled, a part of  SS floated.   Therefore, it is necessary to
   install a scum skimmer or some  other device to remove the floated
   SS.
           Date of measurement:  10/20,  SS in influent to
w
3
H
W
-P
4-1
0)
W
   100 -
    80 -
    60 -
    40 -
    20
            final sedimentation tank: 98 mg/1
                                 2000 x  1000H
                                 Cylinder used
  Floated sludge
o Settled sludge
                     10            20
                        Standing time  (min)
                    30
                                                             -0
                               h20
-40
                                                             -60
                                                             -80
                                                                  •-I
                                                                   U)
                                     a
                                     o
                                                                   CM
                                                              100
    Pig.  22  Sludge settlability in secondary sedimentation
             tank (performance confirmation experiment of
             Company K's process)
                                  266

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5.5  TREATABILITY OF SLUDGE

 5.5.1  Excess Sludge Yield

             The yield of the excess sludge is shown in Table 12.   It was
        not so different from the yield of the excess sludge in the conven-
        tional method.
                                    267

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                                          Table  12-a  Excess sludge yield, Company  I's process
Exp.
No.

D-l
2
3
4
5
6
E-l
2
3
4
5
F-l
2
S
Flow
m3/day
1320
2400
1840
1840
1520
1840
2400
3000
3600
2400
1840
1840
947V1940
2240
Influent
BOD
mg/1
92.2
110
124
85.1
78.1
74.3
87.2
87.4
87.2
90.1
112
126
129
97.9
I
Influent
SS
mg/1
132
125
179
121
104
102
109
99.3
102
114
170
150
132
112
Effluent
BOD
mg/1
8.7
15.5
15.0
7.9
6.9
7.9
12.0
15.2
18.7
16.0
15.0
14.4
15.9
15.6
Effluent
SS
mg/1
24.3
28.0
23.7
15.9
12.1
16.0
9.0
12.0
17.0
16.9
20.0
15.4
16.4
15.2
MLSS
g/i
4.38
3.56
3.23
3.57
3.49
4.02
1.99
1.79
1.76
1.49
2.48
2.83
2.91
2.26
•**
SRT
Day
14.1
2.93
2.59
5.07
16.3
14.3
3.60
2.24
2.02
1.59
2.52
4.42
4.69
1.59
BOD-SS
loading
kg/kg SS day
0.27
0.74
0.94
0.59
0.43
0.44
1.05
1.49
1.78
2.21
.1.14
1.12
1.39
0.98
Inflow
SS load
kg/day
168
301
329
223
159
180
261
297
369
273
309
277
209
251
Outflow
SS load
kg/day
31.7
66.8
43.1
30.1
18.9
28.5
21.3
37.0
60.0
40.7
37.4
27.9
25.9
34.0
Excess
sludge
kg/day
31.0
162
192
69.0
34.2
34.3
233
305
175
206
233
212
158
205
***
Excess
sludge
ratio .
-
0.227
0.692
0.672
0.358
0.244
0.226
0.972
1.17
0.566
0.887
0.858
0.851
0.863
0.945
ro
cri
oo
           *   The analysis of effluent BOD is conducted by low-temperature


               sterilization method.
           **  SRT = —
                       MI.SS * aeration tank volume
                     excess sludge (• outflow SS load
               Excess sludge ratio =
                                                  _   excess sludge
                                           inflow SS load - outflow SS load

-------
Table 12-b  Excess sludge yield, Company K's process
Parameter
Flow (m3/day)
Influent BOD
(mg/1)
Influent SS
(rag/1)
Effluent BOD
(mg/1)
Effluent SS
(mg/1)
MLSS (mg/1)
BOD loading
(kgAg SS day)
Inflow SS load
(kg/day)
Outflow SS load
(kg/day)
Excess sludge
(kg SS/day)
*1
Excess sludge ratio
SRT*2 (day)
Performance confir-
mation (Run IV)
1000 ^ 1100
80.8
77
11.3
18
3240
0.45
80.1
18.7
55.8
0.91
6.0
Applicant's experi-
ment (Run I I- 5)
1015 % 1160
102
146
13.6
33.1
3760
0.49
153
34.6
118
1.00
3.4
*1  Excess  sludge  ratio = -
                                  excess sludge
                          inflow SS load - outflow SS  load
*2  SRT =   total sludge in the system
          excess sludge + outflow SS load
                          269

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  5.5.2  Thickening Characteristics


              Fig.  23 shows the excess sludge thickening curve.   There was
         no particular problem in the thickning of the excess sludge.
                                   Date of
                                   measurement:

                                 • 13 Nov.  80
                                 X 14 Nov.  80
   SS

15980 mg/1
12020 mg/1
sv
    80 -
    60"
    40-
    20-
                           2            5       10

                               Settling time  (hr)
       15
                                                                 20
                                                                          25
         Fig. 23-a  Excess sludge thickening curve, Company I's process
                                     270

-------
   100
<*>
>
    80-
    60 -
    40 '
    20-
            o
                                                    o SS 6700 mg/1
                                                    A SS 9250 mg/1
                               10         15
                              Settling time  (hr)
20
25
30
            Fig. 23-b  Excess sludge thickening curve, Company K's process

   5.5.3  Dewaterability

               The following experiments were conducted to examine the
          dewaterability of the excess sludge.

          (1)   Vacuum filtration (leaf test)
          (2)   Press filtration (leaf test)
          (3)   Belt press filtration (small-sized experimental apparatus)
          (4)   Centrifuge dewatering (small-sized experimental apparatus)

               The results of the experiments are shown in Tables 13, 14, and
          15.   The dewaterability of the excess sludge in the deep well
          biological process was not so different from that in the conventional
          activated sludge process.
                                      271

-------
Table 13  Results of vacuum filtration and press filtration
          tests with excess sludge, Company I's process
Filtration method
Concentration (wt %)
Agents dosed
Dose ratio (wt %)
Filter cloth
Applied vacuum (Torr)
Applied Filtration
pi ess are
(kg/an G) Pressing
Cake thickness (mm)
Sludge volume treated
(m3/m2 hr)
Dry cake yield
(kg/m2 hr)
Water content in cake
(%)
Vacuum filtration
Excess
sludge
1.04
Centrifuged
sludge
5.4
Press filtration
Excess
sludge
1.04
Centrifuged
sludge
5.4
F2C£3 + Ca(OH)2
10+30
Pyrene (A)
260
-
-
2.6
0.69
4.9
81.0
10+30
Pyrene (A)
260
-
-
19.0
0.47
22.6
84.0
10+50
Pyrene (A)

3
10
2.0
/
0.175
1.84
64.0
10+30
Pyrene (A)

3
10
11.0
0.19
10.8
70.0
                             272

-------
   Table 14  Results of dewatering experiment for excess sludge
             by use of belt press, Company I's process
Filtration method
Aeration system
Dry cake Yield
(kg/m hr)
Water content in cake
(%)
Coagulation agent
Dose ratio (wt %)
SS recovery (wt %)
Without thickening
Conventional
method
25M1
84 . 4^86 . 2
High cationic
1.35^1.61
86.4
Deep well
biological
process
20^51
83.2^84.4
-»-
0.98
88.7^91.4
With thickening
Conventional
method
37VL31
77 . 6^83 . 6
->-
l.l(yvL.47.
87.6^93.8
Deep well
biological
process
37VL11
79 . 4^81 . 1
->
1.0
94 . 3^95 . 9
*  Width of belt used 900 mm
   Table 15-a  Results of dewatering of excess sludge with
               centrifuge, Company I's process

Concentration (wt %)
Coagulant dose ratio (wt %)
Centrifugal force (G)
Sludge volume treated (m3/hr)
Dry cake yield (wt %)
Water content in cake (%)
SS recovery (wt %)
Without thickening
0.86
1.16
3140
3.0
26.0
81^83
97^99
With thickening
3.4
1.0
3140
1.0
34.0
80^82
98^99
    Centrifuge used:   Cylindrical conical type,
                      Ball diameter 250 mm4>
                                273

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Table 15-b  Results of dewatering of excess sludge with
            centrifuge, Company K1s process
Parameter
Sludge volume treated
Concentration
Coagulant dose ratio
Centrifugal force
Dry cake yield
(m3/hr)
(W/v %)
(wt %)
(G)
(kg/hr)
Water content in cake (%)
SS recovery
(wt %)
Deep well biological
process
3.5
0.85
1.05
3000
29.5
83.2
99
                 Coagulation agent used for test:  Cationic polymer
                             274

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6.   ECONOMIC EVALUATION
          For the evaluation of economical efficiency of this process, an
     cost estimation was conducted under the following conditions.

     (1)   Influent BOD:  120 mg/1
     (2)   Effluent BOD:  20 mg/1 or less
     (3)   Design flow:   5,000 m3/day, 50,000 m3/day and 300,000 m3/day
     (4)   Two systems or more to be set up.
     (5)   Scope in the estimation
          Deep well aeration tank (Companies I and K)
          Vacuum degasser  (Company I)
          Floatation tank ana degasser (Company K)
     (6)  Geology:
Geological features along the shore of Tokyo Bay
shall be assumed, that is, a silt layer to the
depth of 40 m and gravel layor beneath to the depth
of 100 m.
 6.1  CONSTRUCTION COSTS

           The construction costs based on the estimation for the aeration
      facilities in the deep well biological process are shown in Table 16.
          Table 16-a  Example of estimation of construction cost of
                      Company I's process
Design flow
Dimension of aeration tank
Number of systems
Material (inside/outside)
Construc-
tion
cost,
(Unit:
1000,000
Yen)
Deep well
aeration tank
Vacuum degasser
Compressor
Total
5,000 m3/day
1.1* x iooH
m m
2
Steel pipe/
steel pipe
261
21
13
295
50,000 m3/day
3.6s* x iooH
m m
2
RC/RC
873
20
63
956
300,000 m3/day
3.0^ x 100H
m m
16
Steel pipe/
steel pipe
4525
256
460
52"41
6.0^ x 100H
m m
4
RC/RC
3427
191
460
4078
                                        275

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                        Table 16-b  Example  of estimation of construction costs of Company K's process
ro
^j
cr>
Design flow
Dimension of aeration tank
Material for Inside
aeration tube/outside
tank tube
Number of systems
Construc-
tion cost
(1,000 Yen)

Deep well aeration
tank
Floatation tank
Degasser
Subtotal
Total
5,000 m3/day
1.3 m0 x 100 mH
Steel pipe/
Ductile cast-iron pipe
2-tanks 2-systems
Machinery
126,000
27,000
15,000
168,000
Engineering works
115,000
10,000
5,000
130,000
298,000
50,000 m3/day
2.85 m0 x 100 mH
Steel pipe/
Ductile segment
4-tanks 8-systems
Machinery
620,000
160,000
24,000
804,000
Engineering works
270,000
120,000
6,000
396,000
1200,000

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6.2  REQUIRED LAND AREA
         Table 17 shows the estimated land area required for each facility
               Table 17-a  Required land area, Company I's process
Design flow
Dimension of aeration
tank
Number of systems
Area
(m2)
Deep well
aeration tank
Vacuum degasser
Compressor air
tank
Vacuum pump
Total
5000 m3/day
1.1^ x iooH
m m
2
40
3.7
5.3
3.2
52.2
50,000 m3/day
3.6s* x 100H
m m
2
260
26.8
38.1
9.1
334
300,000 m3/day
3.0^ x 1QOH
m m
16
1904
175
71.9
21.4
2172
6.0s* x iooH
m m
4
1330
126
71.9
21.4
1555
               Table 17-b  Required land area, Company K's process
Design flow
Dimension of aeration
tank
Number of systems
Area
required
(m2)
Deep well aeration
tank
Floatation tank
Degasser
Total
5,000 m3/day
TT
1.3 mtf x 100 m
2-tanks 2-systems
36
126
36
198
50,000 m3/day
2.85 mjzJ x 100 mH
4-tanks 8-systems
182
1260
280
1722
                                     277

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6.3  MAINTENANCE AND OPERATION COST AND REQUIRED ELECTRIC POWER
          Table 18 shows the estimated power required for the aeration
     facilities in the deep well biological process.

           Table 18-a  Electric power required, Company I's process
Design flow

Compressor Kw
Vacuum pump Kw
Return sludge pump Kw
Total Kw
Power consumed per day KwH/day
Power consumed
e , Removed BOD kg
removed BOD
Power consumed per ,, „ / 3
3 ^ KwH/m
1m of sewage
5,000 m3/day
Rated
30
4.4
7.4
41.8



Actual
22
2.0
4.6
28.6
686
1.37
0.137
50,000 mVday
Rated
180
15
44
239



Actual
158
10
35
203
4872
0.974
0.097
300,000
m3/day
Rated
840
88
240
1168



Actual
780
60
210
1050
25200
0.84
0.084
                                      278

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                                   Table  18-b   Electric power required,  Company K's process
FN3
^J
<£>
Design flow

Recirculation pump
Aeration blower
Sludge collector
Degasser blower
Return sludge pump
Total
Power consumed per day
Power consumed per
1 kg of removed BOD
Power consumed per
1 m3 of sewage
5,000 m3/day
Rated KW
7.5X2
3.0X1
1.5X2
1.65X1
5.5X1
28.15
Actual KW
5.6X2
2.0X1
1.1X2
0.7x1
4.0X1
20.1
Power
consumed
KWH/day
269
48
53
16.8
96
482.8
483 KWH/day
0.774 KWH/removed BOD kg
0.097 KWH/m3
50,000 mVday
Rated KW
30X4
14.3X2
1.5X4
5.0X2
22X2
208.6
Actual KW
27.6X4
9.9X2
1.1X4
3.4X2
19.0X2
179.4
Power
consumed
KWH/day
2650
\
476
106
163
912
4307
4307 KWH/day
0.679 KWH/removed BOD kg
0.086 KWH/m3

-------
     From the above results of the estimation, it can be seen that the
land area required for the aeration tank is much less than that for the
conventional method, and the power required is almost the same as in
the conventional method.
                                   280

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7.    RESULTS OF EVALUATION

          From the view points of treatment performance and the actual
     construction experiences, the deep well biological process developed by
     Companies I and K met the goals of development and has been recognized
     as a municipal sewage treatment technology that has already reached the
     stage of practical use as described below.

     (1)  These were practical techniques with a treatment capacity of
          1,000 m3/day or more.

     (2)  These techniques were capable of meeting the legal require-
          ments for the biochemical oxygen demand(BOD) and suspended  '
          solids(SS) in effluents.

     (3)  In the operation of facilities under this process, there was
          no marked difference between this process and the conventional
          methods such as the standard activated sludge process,

     (41  As for the operation and maintenance cost, these techniques did
          not differ greatly  from the conventional method.

     (5)  These techniques had simplicity in taking countermeasures. to
          prevent detrimental effect on surrounding environment.

     (6)  Much less land area was required for the aeration tank in this
          process, compared with the conventional methods.
                                    281

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8.    ADDITIONAL REMARKS

          The following remarks  were added to the final evaluation report.

     (1)   Biochemical oxygen demand(BOD)  of the effluents  from the applicants'
          plants during the experiments  for this evaluation was 20 mg/1 or
          less.
               It is necessary to consider a safety factor to meet the
          effluent standard in the design and operation of the deep well
          biological process, as it is customary done in the design and opera-
          tion of the actual plants.

     (2)   By the employment of the deep  well biological process, the land
          area for the aeration  can be greatly reduced.  However, additional
          facilities for solid-liquid separation are required instead.
               Further, the aeration tank is constructed with a technique
          different from that in the conventional method.
               Accordingly, on the adoption of this process, the complete
          economical analysis must be carried out, with particular consider-
          ation given to the reduced land cost, the construction costs of the
          deep well aeration tank and solid-liquid separation facilities, and
          other costs.

     (3)   For the design and construction of the deep well aeration tank, it
          is necessary to investigate thoroughly in advance:  Earthquake
          resistance, construction method and safety depending on the
          geological structure,  the materials to be used,  and some other
          factors.

     (4)   In this process, the removal of sand, sludge and other matter which
          may settle and accumulate on the bottom of the aeration tank is
          considered to be more  difficult than in the conventional method.
          This must be considered in the design and operation of this plant.
                                   282

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                                       Eighth US/Japan Conference
                                              on
                                      Sewage Treatment Technology
            DEPHOSPHORIZATION
                        OF
SEWAGE  BY CONTACT  CRYSTALIZATION
                        OF
              CALCIUM  APATITE
                  October 1981

                Cincinnati, U. S. A.
     The work described in this paper was not funded by the
     U.S. Environmental Protection Agency. The contents do
     not necessarily reflect the views of the Agency and no
     official endorsement should be inferred.
  Tetsuichi IMonaka

  Senior Technical Advisor,

  Sewage Works Bureau

  Tokyo Metropolitan Government

                         283

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DEPHOSPHORIZATION OF SEWAGE BY  CONTACT CRYSTALLIZATION  OF CALCIUM APATITE

1.  INTRODUCTION
        As a countermeasure to  the pollution of  land-locked waters,  such
   as lakes, swamps and Inland  bays,  due  to eutrophicatlon, a variety  of
   processes for removal of phosphorus, one of the major pollutants, have
   been developed,
        A phosphate crystallization process which theoretically  does not
   liberate sludge has attracted the  Tokyo Metropolitan Government whose
   chronic headache is the lack of sites  for dumping sewage sludge.
   In August 1978,  the Tokyo Metropolitan Government installed a pilot plant
   and related experimental facilities at its Morigasaki Wastewater  Treatment
   Plant to study the phosphate crystallization process.  Although phosphate
   crystallization had already  been demonstrated by a private company  to  be
   effective in treating the secondary effluent of night soil various  engi-
   neering requirements and particulars had yet to be clarified  in its ap-
   plication to the dephosphorization of  sewage.
2.  PRINCIPLES AND FEATURES OF DEPHOSPHORIZATION
 2.1 PRINCIPLES
          Phosphorus in the secondary effluent of sewage exists, for the
                                  3_
     most part, in the form of  PO,  .  When charged with slaked  lime
     (calcium hydroxide), this  secondary  effluent produces calcium hydroxy-
     apatite (Ca (OH)(PO ) ), which,  though extremely low in  solubility,
     remains dissolved and supersaturated in the secondary effluent because
     its precipitation velocity is quite  low at a pH value of 8  to 9.
          In the contact crystallization  process discussed here, hydroxya-
     patite is crystallized and separated selectively and at  a practically
     high speed by bringing it  into contact with a liquid dephosphorization
     media with a low degree of supersaturation and a pH value of 8 to 9
     (crystallines mainly consisting of calcium phosphate) as seeds forming
     crystalline nuclei.
          The secondary effluent of sewage contains, in addition to
     phosphoric acid, 100 rag of carbonates per liter which react with
     calcium ions.
          When slaked lime is injected into the secondary effluent,  these
     carbonates are transformed into CaCOo or CatHCO-)-, which coexists
     with apatite in a supersaturated state to prevent the separation of
     the latter.  Worse, CaCO.  or Ca(HCO_)2 is liberated upon the dephosphori-
                                    284

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    zation media to degrade the latter1s dephosphorization activity.
         The contact crystallization system introduced here is provided
    with a decarbonation process in which raw water is added to sulfuric.
    acid in excess of its M-alkalinity (total alkalinity)  equivalent
    (acid equivalent of CaCO~ necessary to reduce the pH value to 5)  in
    order to convert the carbonates into free ones,  which are then
    aerated for expellation into the open air.
         Then,  slaked lime is dosed to make up Ca ions and hydroxyl ions
            2_i_
    (to a Ca   concentration of about 70 mg/lit., pH 8.5 to 8.8), and the
    decarbonated liquid is brought in contact with the nuclei media
    (dephosphorization media serving as a filter) consisting mainly of
    calcium phosphate for the purpose of dephosphorization.
    The reaction process is as follows.
    5Ca2+ + OH~ + 3P043~ -> Ca5(OH) (PO^
    In this case, the pH value may go up more than necessary if slaked
                                         2+
    lime alone is used to increase the Ca   concentration.   For this
    reason, part of the slaked lime does nay be replaced with CaSO, or
    others.
2.2 FEATURES
         The contact crystallization system has the following features.
  (1) Theoretically sludge-free, except for the sludge stemming from
      suspended solids in the secondary effluent.
  (2) Shorter retention period in each process, and a smaller installation
      space compared with the coagulation sedimentation process  (phosphate
      precipitation process).
  (3) Use of inexpensive chemicals (sulfuric acid and slaked lime) which
      are readily available domestically.
  (4) Recovery of phosphorus from sewage as deposited on the dephosphori-
      zation media.
  (5) No need to reactivate the dephosphorization media, and no need to
      treat wastewater resulting from reactivation, unlike the ordinary
      ion exchange media.
                                     285

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3.  PILOT PLANT OUTLINE
        The conditions  upon which the pilot plant  has  been designed are
   listed in Table  1, and the physical properties  and  chemical composition
   of the dephosphorization media* in Table 2.
        Figure  1  shows  the process flow sheet of  the pilot plant.
   (Refer to Table  1, Table 2 and Fig. 1)
                  Table 1. Pilot plant design conditions and specifications
Effluent to be treated
Planned processing rate
Decarbonation
tank
pH conditioning
tank
Filtration tank
Dephosphoriza-
tion tank
Dimensions
Retention time
Aeration rate
Dimensions
Retention time
Dimensions
Rate of filtration
Dimensions
Linear velocity (LV)
Space velocity (SV)
Dephosphorization media
Secondary effluent of sewage treatment
plant subjected to preliminary removal
of SS by rapid sand filtration
100m3 /day
0.5m x 1 m x 2m (H)
8.6 to 12.9 min.
Oto21m3/hr.
0.8 rnt> x 1 m (H)
5.0 min.
1 m0 x 1 m (H), downward flow pressure
type
5 m/hr.
1mx4.5m(H)
5 m/hr.
2.5 times/hr.
Charge, 1.6m3 ; stuff ing height, 2m
          Table 2 Dephosphrization media - physical properties and chemical composition
Physical properties
Grain size
Uniformity
coefficient
True specific
gravity
0.44 mm
1.59
2.62g/cm3
Chemical composition, %
P20S
CaO
C02
34.8
52.6
4.5
H2O
SO4
Na30
1.6
1.4
1.1
SiOj
MgO
A«20,
0.5
0.6
0.3
K20
Ingition loss
Others
0.1
1.9
4.1
* In order  to  obtain high-efficiency dephosphorization media of uniform
  quality,  phosphate rock was treated as  follows.   First, phosphate  rock
  was pulverized and classified by size.   Phosphate powder of a uniform
  size was  then  treated in an aqueous solution of  potassium hydrophosphate
  and an alkaline solution of calcium chloride to  form fine apatite
  crystallines over phosphate particles.
                                     286

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                  Flow

                  meter
   D
       <^H
      Blower (1)   1
                A
Flowmeter          \
   fl
        I ~. "J—iT. Flowmetet
        flower (21
          Backvvashmg pump
                          Decarbonation tank  pH conditioning
                          Jbicarbonate release)  tank
                                                                           Effluent
Influent pump
                                Fig. 1  Pilot plant
  4.  RESEARCH METHODS


            An  infiltrate  through a high-speed sand filter of  the  secondary


      effluent  available  from the Morigasaki Wastewater Treatment Plant was


      supplied  around the  clock  to the pilot plant for  study.


            1st  stage  (September  1978  to July 1979):  The process  flow used


      is  illustrated  in Figure 2.  (Refer to  Fig.  2)





                        Sulfuric acid  CO,    Lime
                            I	L   A
          Influent

          (secondary effluent-

          of sewage plant)
Decarbonation procest



Lima mixing arxJ pH



Dephosphor
process
A Retention time, 13 mm Retention time, 5 mm Retention time
Air
zation
24 mm
                                                                      Effluent
                                  Fig. 2 Process flow for 1tt stage of study
                                              287

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         2nd  stage (August  1979 to  May  1980) and  3rd stage  (June 1980  to
  March 1981):   According to  the  results  of  the first stage  study, an
  intermediate  filter process was installed.   Prior  to each  of these
  stages, the dephosphorization media was renewed. (Refer to Fig.  3)
                   Sulfuncacid C02
                                      Lime
Influent
(secondary effluent of
sewage treatment plant)
Decarbo nation process
(bicarbonate release)



conditioning process


Sand filtration
process


Dephosphonzalion
process
                                                 Effluent
                        Detention time, 13 mm   Retention time, 5 n
                      Air
                                                      Rate of filtration, 120m/day SV - 2 b times/nr, LV • 120 Hi/day
                                      Fig. 3 Process flow for 2nd stage of study
4.1  RESULTS  AND DISCUSSIONS
  4.1.1  Raw  Water Quality
                The monthly averages of  the water  characteristics  concerning
          the  crystallization  reaction  are shown  in Table  4.
                         Table 3  Measuring Items and methods of analysis
             Measuring Item
   Unit
         Method of analysis
        PH

        Turbidity

        Total alkalinity (as CaCO3 }

        Calcium ion

        Total phosphate

        Orthophosphate
        Dissolved Orthophosphate
        Total carbon dioxide
        Free CO2
   deg.

  mg/lit.

  mg/lit.

  mg/lit.

  mg/lit.
  mg/lit.
mgCOj/lit.
mg COZ /lit.
Glass electrode method (specified in the
Standard Methods for the Examination of
Sewage)
Transmittance measuring method (speci-
fied in the Standard Methods for the
Examination of Drinking Water)
Titration with N/50 HCI (specified in the
Standard Methods for the Examination of
Sewage)
EDTA titrimetric method (specified in the
Japanese Industrial Standards)
EPA methods for chemical analysis of
water and wastes (Ammonium persulfate
digestion and colorimetry)
EPA methods for chemical analysis of
water and wastes (direct colorimetry)
Ditto
Diaphragm type CO? electrode method
ditto
                                           288

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Table 4(a)  Quality of influent (1st stage of study)
~~~""~ ~~~-^^^ Date
Characteristic — --
Water temperature
°C
pH
Total Alkalinity,
mg/lit.
Ca+2 mg/lit.
Total P mg/lit.
PO4-P mg/lit.
Dissolved P04 -P
mg/lit.
Turbidity deg.
Total COj mg/lit.
Free CO, mg/lit.
Oct.
1978
21.3
6.65-
7.14
83
29
2.52
2.41
2.38
0.52
88
8.3
Nov.
1978
18.0
6.60-
7.14
86
28
2.68
2.43
2.41
0.83
88
9.6
Dec.
1978
16.4
6.95-
7.15
116
30
3.13
2.93
2.93
1.47
114
12.5
Jan.
1979
14.7
6.75-
7.10
93
L. 28
2.01
1.93
1.85
0.95
94
^12.3
Feb.
1979
14.8
6.82-
7.09
103
27
1.67
1.59
1.53
1.45
107
11.8
Mar.
1979
14.7
6.72-
7.05
97
28
1.76
1.69
1.65
1.34
101
12.6
Apr.
1979
17.3
6.45-
7.00
66
27
1.88
1.79
1.74
1.24
68
11.4
May
1979
19.7
6.63-
6.85
54
27
1.59
1.52
1.49
1.02
58
12.3
Jun.
1979
23.1
6.70-
7.10
81
26
1.79
1.67
1.65
1.37
83
13.8
Jul.
1979
24.3
6.72-
7.10
72
28
1.81
1.75
1.72
0.75
78
13.8
Table 4(b)  Quality of influent (2nd stage of study)
~~~ -^—-_^_^ Date
Characteristic^—-^
Water temperature
"C
PH
Total alkalinity
mg/lit.
Ca+2 mg/lit.
Total P mg/lit.
PO4 -P mg/lit.
Dissolved PO4 -P
mg/lit.
Turbidity deg.
Total COj mg/lit.
Free CO2 mg/lit.
Aug.
1979
26.1
6.76-
7.13
62
29
1.79
1.73
1.71
0.60
68
12.4
Sep.
1979
24.5
6.75-
7.00
66
28
1.79
1.75
1.74
0.82
63
10.6
Oct.
1979
21.6
6.70-
6.99
60
29
1.26
1.20
1.18
1.24
63
11.6
Nov.
1979
18.7
6.75-
6.94
55
29
1.42
1.37
1.34
1.17
60
13.0
Dec.
1979
16.5
6.70-
6.94
61
28
1.51
1.45
1.42
1.45
66
14.1
Jan.
1980
14.4
6.75-
7.05
73
28
1.55
1.45
1.43
1.69
82
13.8
Feb.
1980
14.4
6.88-
7.17
99
27
1.86
1.75
1.72
2.07
112
15.5
Mar.
1980
15.8
7.00-
7.12
100
28
1.80
1.66
1.64
2.06
119
15.2
Apr.
1980
17.8
6.80-
7.15
80
26
1.64
—
- '
1.91
85
-
May
1980
19.1
6.83-
7.15
80
26
1.89
—
-
1.77
80
-
Table 4(c)  Quality of influent (3rd stage of study)
^^~— -~^_^^ Date
Characteristic—---^^
Water temperature
°C
pH
Total alkalinity
mg/lit.
Ca+2 mg/lit.
Total-P mg/lit.
Turbidity deg.
Total carbonate
mg/lit
Jun.
1980
23.8
6.90-
7.01
83
28
1.90
1.26
87
Jul.
1980
23.3
6.69-
7.04
66
29
1.37
1.35
70
Aug.
1980
23.5
6.77-
7.04
58
30
1.28
0.84
60
Sep.
1980
22.7
6.71-
6.92
60
30
1.43
0.84
81
Oct
1980
20.6
6.64-
6.99
72
30
1.49
1.09
74
Nov.
1980
18.8
6.80-
7.07
80
30
1.57
0.93
85
Dec.
1980
16.7
6.84-
7.19
83
30
1.66
1.02
76
Jan.
1981
14.1
6.86-
7.14
93
29
1.87
1.58
102
Feb.
1981
13.9
6.89 ~
7.02
94
28
1.72
2.04
108
Mar.
1981
16.3
6.62 ~
7.62
82
27
1.64
2.30
84
                          289

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           The M-alkalinity governing the sulfuric acid requirement for
      the decarbonation process varied in the range of 54 to 115 rag/lit.
      with 75 rag/lit, as an average;  it decreased in summer, but in-
      creased in winter.  It was  also low when the nitrification was
      active or when it was rainy.
           The total phosphorus in the raw water was in the range of
      1.5 to 2.0 mg/lit. for most months and showed an annual average
      of 1.62 mg/lit. in 1980,  suggesting that the raw water used was
      representative of secondary effluents so far as the phosphorus
      concentration is concerned.
           In passing, the annual average of the total-phosphorus
      concentrations of the secondary effluents from the eight waste
      water treatment plants within the wards of Tokyo is in the range of
      1.13 to 3.14 mg/lit. or 1.92 mg/lit.  on the average,  and phosphorus
      is present,  primarily in the form of  dissolved orthophosphate.
           Calcium ions which are effective in the crystallization
      reaction remained almost constant at  about 30 mg/lit. throughout
      the test stages.
           The carbonates which affect the  crystallization reaction were
      present at a level of 60 to 120 rag/lit, in terms of total carbonate,
      and changed almost in proportion to the change in M-alkalinity.
4.1.2 Decarbonation
           In the decarbonation process, raw water was acidified with
      sulfuric acid, and was aerated  to liberate carbonates, which
      were then subjected to air stripping.  The injection rate of
      sulfuric acid was held at 150 mg/lit. up until March 1979, but
      from April 1979 was controlled  to attain a pH value of 3.
           In order to improve the decarbonation efficiency, the
      aeration rate was changed little by little during the study period,
      and the tanks were modified as  well.   Figure 4 shows the changes
      in the monthly averages of total-carbonate concentrations in the
      influent and decarbonated water.  Table 5 shows the relationship
      between the running conditions  and decarbonation efficiency.
      As is clear from Table 5, the total-carbon concentration of the
      secondary effluent could be held low at about 10 mg/lit. by in-
      jecting air at a gas-to-liquid  ratio  of 3 in the plug flow system.
      (Refer to Fig. 4, Table 5)
                                    290

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   8
o
o
1
S
to
I

I 8


I
        Oct.  Nov  Dec.  Jan  Feb  Mar.  Apr. May  Jun.  Jul.  Aug.  Sep.  Oct. Nov. Dec. Jan.  Feb.  Mar.  Apr.  May


        1978           1979                                                       1980





                       Fig. 4 Monthly averages of total carbonate in the influent and decarbonated water
              Table 5 Operating conditions of decarbonation tank, and decarbonation efficiency
Period
Type of decarbona-
tion tank
Gas-liquid ratio (G/L)
Total carbonate in
influent mg/lit.
Total carbonate in
decarbonated water
mg/lit.
Carbonate removal rate
%
Octto
Nov.. 1978
Dec. 1978
to Jan. 1979
Jan. 1979
Feb. to
Jun., 1979
Single-stage complete mixing
1
90
39.9
55.8
2
107
36.0
66.4 .
3
108
33.8
68.7
5
105
22.9
81.1
Jun. to
Aug., 1979
3-horizontal
staggered baffle
4- turn flow
3
73
16.6
77.2
Aug. 1979 to
Mar. 1981
3-vertical
staggered baffle
4-turn flow
3
81.2
13.9
82.9
                                                      291

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 4.1.3 Dephosphorization  and Reaction  Products

             In the first  stage of  the  study, the  changes in  phosphate

       concentration of  influent and effluent were as shown  in Figure

       5  and Table 6.  (Refer to Fig. 5,  Table 6)
    4.0 -
    3.5 -
    3.0 -
    2.5 -
CO
.c
Q.
c/)
O

Q.
2.0 -
    1.5
    1.0 -
    0.5 -
                             Effluent
              Oct.   Nov.  Dec.  Jan.    Feb.  Mar.   Apr.   May   Jun.   Jul.
                    1978                          1979
     Fig. 5 Monthly changes of phosphate concentration in the first stage of study
                                  292

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          Table 6  Phosphate concentration in the first stage of study
Sample
Influent
Effluent
Date
Characteristic" 	 ^
Total phosphate
mg/lit.
Dissolved orthophos-
phate mg/lit.
Total phosphate
mg/lit.
Dissolved orthophos-
phate mg/lit.
Oct.
1978
2.52
2.41
0.12
0.07
Nov.
1978
2.68
2.43
0.35
0.28
Dec.
1978
3.13
2.93
0.59
0.51
Jan.
1979
2.01
1.93
0.48
0.45
Feb.
1979
1.67
1.59
0.47
0.42
Mar.
1979
1.77
1.69
0.44
0.40
Apr.
1979
1.88
1.79
0.53
0.51
May
1979
1.59
1.52
0.53
0.50
Jun.
1979
1.79
1.67
0.49
0.45
Jul
1979
1.82
1.75
0.49
0.48
     For  about  one and a half months after the start of  the
operation,  the  phosphate concentration in the effluent was  kept
as  low  as 0.1 to  0.2 mg/lit.   This was due to crystallization
synergy,  and adsorption to the surfaces of dephosphorization
media,  etc.,  in the early stages of water supply.
     In December,  three months later,  the phosphate concentration
reached 0.77 mg/lit.   It was inferred that an increased  amount of
residual  carbonates  in the influent of dephosphorizing tank owing
to poor decarbonation might have reacted with calcium ions  to
encrust calcium carbonate over the dephosphorization media  thus
halting the  dephosphorization activity.
     Later the  operating conditions of the decarbonating tank
were improved.  As a result, the concentration had been  stabilized
at about  0.5 mg/lit.  from January 1979 till the end of the  1st
stage of  the  study in July 1979.   To check the surface changes
of the dephosphorization media,  the chemical composition of flak-
ings from the dephosphorization media were analyzed.
     The  results were as shown in Table 7.  It is evident that
the surfaces of the  dephosphorization media were covered mainly
by calcium carbonate.  (Refer to  Table 7)

               Table 7 Chemical composition of reaction products
Sample

Fresh dephosphorization
media
Dephosphoruation media
after three months of use
Chemical composition*
Apatite
100%
22.0%
Calcium carbonate
0
59.3%
 'Note:  Calculated from the analyses of P and Ca
                            293

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    2.0
    1.5
    1.0
,§
Q.
     0.5
                  In the first stage  study it was  found that calcium carbonate
            produced in slaked  lime  and water served as a barrier  to crystalli-
            zation.  In the second  stage study, a sand filter was  applied
            before the dephosphorization process  to  remove calcium carbonate,
            and  the dephosphorization media was renewed.
                  Figure 6 and Table  8 show the phosphate concentrations in
            the  influent and effluent in the second  and third stages of the
            study. (Refer to Fig.  6, Table 8)
I • *



o °

o o
o
) O
1 1 1 1 1 1 III
tug. Sep. Oct. Nov. Dec. Jan. Feb. Mar. Apr. May
979 1980
0 (
•




O


i i I
Legend
• Influent
O Effluent

0 0 0 °


,1,1




O
•-\


j i



>



i Jun. Jul Aug. Sep. Oct. Nov. Dec. Jan. Feb. Mar.
1981
                                                    (continued use of dephosphori-
                                                    zation media used in the pilot plant)
                             Fig. 6  Phosphate concentrations in influent and
                                  effluent (Aug. 1979 to Mar. 1981)
                                       294

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                  Phosphate concentrationi in the influent and effluent
                  (Jun. 1980 to Mar. 1981)
         2.0
         1.5
    -    1.0
         0.5
             Jun.  Jul.  Aug.   Sep.  Oct.   Nov. Dec.  Jan.   Feb.  Mar.
             1980                                    1981
               Dephosphonzation media replaced prior to start of study
                                 Fig. 6 (continued)
Table 8  Phosphate concentrationi in influent and effluent (Aug. 1979 to Mar. 1981}


Influent


Effluent


Total phosphate (mg/£)
Total
orthophosphate (mg/C)
Dissolved
orthophosphate (mg/fi)
Total phosphate (mg/£)
Total
orthophosphate (mg/£)
Dissolved
orthophosphate (mg/fi)
Aug.
1979
1.79
1.73
1.71
0.04
0.02
0.01
Sep.
1979
1.79
1.75
1.74
0.07
0.05
0.04
Oct.
1979
1.26
1.20
1.18
0.11
0.08
0.08
Nov.
1979
1.42
1.37
1.34
0.23
0.21
0.20
Dec.
1979
1.51
1.45
1.42
0.34
0.30
0.29
Jan.
1980
1.55
1.45
1.43
0.65
0.59
0.57
Feb.
1980
1.85
1.74
1.71
0.67
0.64
0.61
Mar.
1980
1.80
1.66
1.64
0.29
0.26
0.25
Apr.
1980
1.64
1.54
1.54
0.26
0.25
0.23
May
1980
1.91
1.83
1.81
0.29
0.27
0.25


Influent


Effluent


Total phosphate (mg/fi)
Total
orthophosphate (mg/C)
Dissolved
orthophosphate (mg/fi)
Total phosphate (mg/E)
Total
orthophosphate (mg/C)
Dissolved
orthophosphate (mg/C)
Jun.
1980
1.90
1.81
1.79
0.07
0.05
0.04
Jul.
1980
1.37
1.34
1.31
0.16
0.14
0.12
Aug.
1980
1.28
1.23
1.22
0.15
0.13
0.12
Sep.
1980
1.54
1.50
1.49
0.19
0.16
0.14
Oct.
1980
1.55
1.49
1.47
0.22
0.19
0.18
Nov.
1980
1.62
1.57
1.55
0.26
0.23
0.22
Dec.
1980
1.75
1.66
1.65
0.29
0.27
0.25
Jan.
1980
2.00
1.87
1.87
0.30
0.26
0.25
Feb.
1980
1.83
1.72
1.71
0.28
0.25
0.24
Mar.
1980
1.64
1.52
1.50
0.29
0.26
0.24
                                       295

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      The concentration of total phosphate in the effluent was
 kept at less than 0.1 rag/lit,  for about  three months after the
 start of the second stage study and for  about one and a half
 months after the start of the  third stage of study.   Just as  in
 the first stage, this was caused by crystallization  synergy and
 adsorption to the surface of the dephosphorization medium.
 Compared with the first stage,  the phosphate concentration in
 the effluent was low.  This was because  the inflow of calcium
 carbonate and other contaminants ,into  the dephosphorization tank
 was reduced sharply to maintain the performance integrity of
 the dephosphorization media for an extended period.
      After four months, the total phosphate concentration had
 increased to 0.2 mg/lit., and  five months later,  it  had increased
 to  0.3  mg/lit.   Subsequently, however, the  total  phosphate
 concentration remained unchanged.   This  concentration level was
 lower than 0.5 mg/lit.,  showing the effectiveness "of the improve-
 ment  of the decarbonation process  and  the installation of the
 sand  filtration process.
      With the supply  of influent,  the  leakge of  phosphate increases
 gradually and finally reaches an equilibrium state.   During the
 March-May period of 1979,  when  the process  was  deemed to be
 stabilized,  the total phosphate concentration was 0.18 to 0.34
 mg/lit.  or 0.28 mg/lit.  on the  average,  which seems  to represent
 the performance of  the contact  crystallization  process.
      In January,  the  effluent showed a high phosphate concentration,.
 This  was because the  decarbonation tank  was run  at a pH value of
 3.5,  which reduced  the injection of slaked lime necessary for
-neutralization to cause insufficiency  in the calcium ions required
 for dephosphorization.   When the pH value was reset  to 3, the
 phosphate concentration level was  reestablished.
      To investigate the properties of  the reaction products
 deposited on the dephosphorization media,  elementary analysis of
 surface layers of the dephosphorization  media was conducted using
 an  X-ray microanalyzer.   It was found  that the Ca/P  ratio became
 larger  after use than it was before.  It was thus inferred that
                                 296

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      the increase  in  Ca  might have been caused by the formation  of
      calcium carbonate.
           Also, a  chemical  analysis of solids in the backwashings of
      the dephosphorization  tank was conducted in order to evaluate  the
      properties of reaction products.   Calcium carbonate was  found  to
      be 35%, or half  as  much as that recorded in the. first stage of
      the study, thus  proving the effectiveness of sand filtration tank
      installation.
4.1,4 Sludge and its Disposal
           Phosphate removed in the contact crystallization system makes
      the dephosphorization  media grow, but causes no sludge.   But the
      contact crystallization system produces sludge in the form  of
      solids in the sand  filtration tank and backwashings in the
      dephosphorization tank.
           In the first stage  of the study, sludge was developed  from
      the dephosphorization  tank alone.   It was generated at a  rate
                3
      of 4.2 g/m  of effluent.   In  the  second stage of the study, the
      sludge was generated from the sand filtration tank at a rate of
             2
      4.9 g/m  and from the  dephosphorization tank at a rate of 0.45
         3                3
      g/m ,  or about 5 g/m   in to to,  which  is far smaller than  in any
      other  method.
          These wastes should preferably be handled from the viewpoint
      of the entire sewage treatment  facilities,  including the p'rimary
      and secondary treatment,  and  may  well be turned back to the
      primary settling tank.    The increase  in the loadings due to return
      sludge is  calculated as  shown in  Table 9.  (Refer to  Table 9)
                         Tabto9 Effects of backwashings


Backwashings from rapid
sand filter
Backwashings from dephosphorize
dephosphorization tank
Total
Backwashing wastes per m3
of effluent
Water (m3 )
0.05
0.01
0.06
SS(g)
4.9
0.45
5.35
Phosphate (g)
0.05
0.05
0.1
Increase in loading* (%)
Water (m3 )
5
1
6
SS(g)
3.3
0.3
3.6
Phosphate (g)
1.25
1.25
2.5
Note*: Calculated on presupposition that the influent into the primary sedimentation tank contains
      150 mg-SS/lit. and 4 mg-phosphate/lit.
                                     297

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4.1.5 Phosphorus Balance
           According to the measurements taken during the March to May
      period of 1979 when the dephosphorization became stabilized, the
      phosphorus balance was determined as shown in Figure 7.  It was
      found that 77% of influent phosphorus was fixed in the dephosphori-
      zation tank,  16% carried away with the effluent, and about 7%
      removed in the form of backwashings. (Refer to Fig. 7)
            Fixed, 4g/day
Fixed, 136g/day
      1
Influent
178g/day

tank
Dephosphorization tank
influent
169g/day

tank
Effluent
28 g/day
                                           Backwashings, 5 g/day
           Backwashings, 5g/day
                    Fig. 7  Phosphate balance (Mar. to May, 1980)

          Phosphorus  fixed  and removed in the dephosphorization tank
      is  regarded  to be  in the form of calcium hydroxyapatite (Ca,(OH)(PO,)„)
      Namely,  the  solids to  be accumulated upon the dephosphorization
      media will be  5.4  times  as heavy as the  phosphorus to be removed.
      The gravimetric  growth of the dephosphorization media for a year
      of  plant  operation is  calculated as follows.
      136 g/day x  5.4  x  365  days = 268 kg/year
      This increase  is 13.4% to 2,000 kg  of dephosphorization media.
      No  visible volumetric  increase was  noticed for about 10 months
      of  operation,  however.   The theoretical  volumetric increase is
      calculated to be about 4% in terms  of grain size if the dephophoriza-
      tion media particles are assumed to be spherical.
4.1.6 Chemical Injection  Requirements
           The chemicals  used in the contact  crystallization system are
      sulfuric acid for the decarbonation process  and slaked lime for
      the pH conditioning process.
           Slaked lime  injection is required  for the purpose of generating
      the calcium ions  necessary for maintaining a proper crystallization
      velocity and also for obtaining a  pH value suitable for crystalli-
      zation.
                                    298

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           It was  found  in basic studies  that decarbonation is carried
     out  smoothly when  the pH value is maintained at 4.5.
           The pH  value, however, was set at 3 because the process was
     designed to  use slaked lime alone for generating calcium ions,
     and  the injection  rate of sulfuric  acid became 140 mg/lit. on the
     average, or  an overdose of 50 to 60 mg/lit.
           According to  the surveys of the factors affecting dephosphori-
     zation  (which will be discussed later), it was found that slaked
     lime  was not the only usable calcium ion source.
     According to practicality and economics, chemical injection may
     be modified  as follows.
           a. Injection  of sulfuric acid  for adjustment of pH to 4
             and  for decarbonation
             Alkalinity equivalent + 10  to 15 mg/lit.
             The  pH value is adjusted with slaked lime to 8.5.
             A shortage of calcium ions  is made up by inexpensive
             calcium sulfate.
           b. Injection  of slaked lime
             15 to 25 mg/lit. (depending on alkalinity)
           c. Injection  of calcium sulfate (total calcium ion make-up:
             40 mg/lit.)
             100  to 120 mg/lit.
          By applying these to the representative quality of the
     secondary effluent from the Morigasaki Wastewater Treatment Plant,
     the injection rates are calculated as follows.
     .  Sulfuric acid                 :   80 mg/lit.
     .  Slaked lime                   :   15 mg/lit.
     .  Gypsum                        :   120 mg/lit.
4.1.7 Treatment  System and its Control
           The  pilot plant findings  suggest that the practical plant
      have the  following treatment system and control.
           Figure 8 shows a flow.sheet  for the suggested plant.
      (Refer to  Fig.  8)
                                    299

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    ISulfuric acidl
                              Slaked lime
^
2
T
L ~
Influent
	 [7
[
Decarbonatio
(bicarbonate
7]
]
i tank
elease)



T
2
E— Q
[
pH condition
tank
D
]
ing



Rapid filtration
tank



Dephosphoriza-
tion tank

Effluent
               Air
                              Fig. 8 Naw process flow
         a. Control of sulfuric acid injection
                 Control of sulfuric acid injection rate according to  the
            pH value of the decarbonation tank.
         b. Control of aeration
                 Proportional flow control of air into the decarbonation
            tank according to a preset gas/liquid ratio.
         c. Control of calcium injection
                 The calcium generation rate is dependent on the influent
            flow rate and phosphate concentration.  Each individual Waste-
            water treatment plant has a phosphate concentration of its own,
            which does not change greatly.  Thus, it is possible to preset
            the make-up requirement according to a preliminary survey.
            Namely, a gypsum solution is subjected to proportional flow
            control, and slaked lime is injected so as to control the  pH
            conditioning tank at a preset pH value.
         d. Water flow rate control
                 The flow rate of water through the sand filtration tank
            and dephosphorization tank should preferably be fixed.
         e. Backwashing of sand filtration tank and dephosphorization  tank
                 Backwashing is automatically carried out by making use
            of an interval timer or by detecting a head loss.
S .  FACTORS INFLUENCING DEPHOSPHORIZATION
        In the contact crystallization system, the factors that are
   considered influential to the dephosphorization reaction include pH,
   calcium ion concentration, carbonate ion, other coexistent ions, water
   temperature, and contact time.
                                    300

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            Batch  tests were conducted  to  evaluating these factors,  followed
       by continuous  process tests using a small-scale monitor plant annexed
       to the pilot plant.
     5.1 MONITOR PLANT EQUIPMENT
              The  monitor plant has the same  configuration and functions as
         the pilot plant,  except that its  10  cm-diameter acrylic resin
         dephosphorization reactor  is  filled with dephosphorization media to
         a height  of 1 m and  that  its  size is reduced one-hundredth that of
         the pilot  plant.
              Three series of monitor  plants were installed  in parallel with
         the pilot  plant.  Each  series was  designed  to be  operable independent
         of  the  others to enable three different tests to  be  conducted
         simultaneously.
              The  process flow of  the  monitor plant  is as  illustrated in
         Figure  9.  (Refer to Fig. 9)
Overflow
   from Air compressor
                        Decarbonating tank  PH conditioning Backwashln9s-
                                      tank
                                                                            Effluent
                                                             No. 1    No.2   No. 3
                                                                 Dephosphoriza
                                                                  tion tank
                           Fig. 9 Monitor plant process flow
                                       301

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5.2 EFFECTS OF CARBONATES
         Upon empirical  corroboration  that  the presence  of  carbonate
    ions has a significant  bearing  upon the velocity  of  the reaction
    between phosphate ions  and  calcium ions to produce sediment,  Zoltek
    (JWPCF, Nov.  1974) and  Ferguson (JWPCF,  Apr.  1973) proposed  the
    following empirical  formula.
                                                       3
    Where,  CO  :   Total-carbonate  concentration  (rools/m )
              k:   Proportional  constant
              n:   Exponent (1.00 to  1.28)
             Kd:   Dephosphorization  velocity coefficient
                  t ,3n-2 .   ,n-l , .
                  (nl    /raol   .h)
         According to this formula,  it is  found  that  the  rate at  which
    calcium phosphate is produced  is in  inverse  proportion to the carbonate
    ion concentration;  namely,  that  the  presence of  carbonate ions
    seriously affects dephosphorization.
         On the other hand,  if  calcium ions are  injected  into a liquid
    in which phosphate and carbonate coexist in  order to  crystallize
    apatite, apatite and calcium carbonate will  crystallize concurrently
    to cover up the surfaces of, and hence degrade the activity of,  the
    dephosphorization media. This fact  was confirmed during the first
    stage of study on the  pilot plant.
         For these reasons,  the following  tests  were conducted to further
    clarify the effect of  carbonate  concentration upon dephosphorization.
 5.2.1  Relationships  between Carbonate and  Effluent Phosphate
       Concentrations
            By making use  of the monitor plant,  the carbonate  concentra-
       tion  in the influent  was  changed in  six steps  over  a  range  of 10
       to 50 mg-CO?/lit.,  and the  influent  was run at a space  velocity
       (SV)  of 5/hr.  to  compare  the  respective phosphate concentrations
       in the effluent.  (Refer  to Fig. 10)   As shown  in Figure 10, there
                                   302

-------

Test 1
Test 2
Test conditions
Concentration of carbonate
in the influent
50mg/8, 30mg/e, 20mg/e
40mg/«, 20mg/K, 10mg/e
Passing time
(H)
700
700
    0.7
     0.6
2
ro
!„ °-5
*l
O «
2 a
•sl
     0.4
 :si  0.3
o.S
                                 O
                                            Legend
O
•
Test 1
Test 2
                                              Monitor column test
                                        I
                                                        I
        0       10      20       30       40       50      60
           Concentration of carbonate in the influent (avg.) [mg/C as C02 ]
       Fig. 10  Relationship between carbonate concentration in the influent
              and phosphate concentration in the effluent
was a  proportional relationship between the phosphate concentration
in the dephosphorization tank influent  and that in  the effluent;
it was confirmed that  the phosphate  concentration in the effluent
could  be  reduced linearly with increase in the degree of decarbona-
tion.   It was also found from Figure 10 that it is  necessary to
decarbonate the influent to about 10 mg-CCL/lit. in terms of C02
if the phosphate concentration in the effluent is to be reduced
to about  0.3 mg-P/lit.
                                   303

-------
5.2.2 Effects of Non-decarbonated  Carbonates
           While it  was  found,  as  discussed  in  5.2.1,  that  the  omission
      of the decarbonation process detrimentally  effects  the effluent,
      a dephosphorization process  without  the decarbonation step  (here-
      inafter referred to as the direct  process)  was  examined using the
      monitor plant  to investigate the effects  of pH  and  calcium  ion
      concentration  in the influent of the dephosphorization tank upon
      dephosphorization.
           In the direct  process,  the effects of  carbonates in  the
      influent are inevitably present, and the  experimental conditions
      were formulated accordingly.
           In the direct  process (1),  the  influent was run  into the
      dephosphorization  tank after its pH  value was adjusted to 9.5
      with- slaked lime.   This high pH value  was intended  to increase
      the crystallization velocity of apatite to  counteract the decline
      in crystallization  velocity  due to carbonates,  and  at the same
                                       2+                             2-
      time to minimize the supply  of  Ca   because a high  ratio  of C0_
      present at this level of pH  value made the  development of calcium
      carbonate easier.
           In the direct  process (2),  the  pH value was set  at 9.0 to
      defy the formation of calcium carbonate.
      The decline in  the  crystallization velocity of apatite was improved
                                             2+
      by injecting calcium  chloride to set Ca   concentration at 60 mg/lit.
           The  dephosphorization media charged into the monitor plant
      column was fetched  from the dephosphorization media being used in
      the pilot plant.
           In the direct  process,  the influent was the same as the
      filtrate  used in the  pilot plant that was obtained by filtering
      the secondary effluent of the Morigasaki Wastewater Treatment
      Plant  trhough a sand  filter.
           In a standard  process  taken as a control,  the influent for
      the pilot plant dephosphorization tank was employed.
           The  test period  and  test conditions are listed in Table 10.
      (Refer to Table 10)
                                   304

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                          Table 10 Test conditions
Test No.
Control
1
2
Name
Standard process
Oephosphorization tank
Direct
process
(1)
Direct
process
(2)
Dephosphoriza-
tion tank
Sand filter
Dephosphoriza-
tion tank
Sand filter
Test period
Feb6-Mar.31
Apr 1-Mar.16
Feb. 6 -
Mar. 31
Apr. 1 -
May 16
Flow velocity
SV, 1/hr.
2.5
2.5
2.5
5.0
2.5
5.0
LV, m/hr.
2.5
2.5
2.5
5.0
2.5
5.0
Design
pH
8.5
8.5
9.5
-
9.0
-
Ca2+ injec-
tion rate
L (mg/2)
50
60
30
-
60
-
Chemicals
used
H2S04
Ca(OH)2
Ca(OH)2
CaCI2
Ca(OH)2
      Figure 11  and  Table 11 show  the  test  results  of  direct


process (1), direct process (2)  and the standard process.


(Refer  to  Fig.   11,  Table 11)
    2.5
S  2.0
.c
Q.

o
-C
Q.

"(5

B  1.5
o
c
8

o
o
1.0
   0.5
  1980
                    O Concentration of total phosphate in influent


                    Q Total phosphate in the effluent not subjected to decarbonation


                    ^ Total phosphate in the effluent in the standard process
                                                       pH = 9.0

       Direct process (1)  pH = 9.5  i   Direct process (2)   +CaCe2
     2/5
                   3/5
4/5
5/5
Fig. 11  Comparison of phosphate concentration in the effluent for standard process

        and direct process
                                   305

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     Table 11  Phosphate concentrations in the sand-filtered influent and effluent in both processes
Test No.
1
2
Remarks
Test period
Feb. 6 -
Mar. 31
Apr. 1 -
May 16

Influent
1.19- 2.24
•(1.70)
0.82- 2.18
(1.64)
Filtrate of sec-
ondary effluent
through a quick
sand filter
Standard process
Filtrate of influ-
ent through
sand filter
1.13- 2.16
(1.65)
0.66 - 2.02
(1.53)
effluent
0.28 ~ 0.37
(0.32)
0.21 ~ 0.35
(0.29)
Decarbonated with pH value of
influent adjusted at about 3.0,
and then adjusted with Ca(OH)j
to a pH value of about 8.5.
Direct process
Filtrate of influ-
ent through
sand filter
0.27- 1.36
(0.96)
0.60 - 1 .85
(1.19)
effluent
0.38- 1.10
(0.77)
0.35- 1.15
(0.75)
Direct injection of chemicals into
the influent
(1) Ca(OH)2
pH = 9.5
(2) CaC82
Ca(OH)2
pH = 9.0
                    Note: The values in parentheses denote the average values within the test period.

           In  direct  process  (1) where the pH value  was set at 9.5,  the
      phosphate  concentration was  higher and more  changeable compared
      with the standard process, making dephosphorization astable.
      This was because despite  a high pH value  set for an increased
      susceptibility  to crystallization of apatite,  coexistent carbonates
      reduced  dephosphorization rate to increase the phosphate concentra-
      tion in  the effluent.  The formation of calcium  carbonate increased
      the volume of SS. (Refer  to  Table 12)

                     Table 12 SS* discharged from both processes
Item
SS discharged from
each process [g/m3 ]
SS discharged from
the entire process
[g/ms ]
Standard process
Sand filter
5.0
Mephosphomatton
tank
0.29
5.29
Direct process (1)
Sand filter
13.4
Ddephosphorization
tank
1.05
14.5
Direct process (2)
Sand filter
8.61
Ddaphosphonzation
tank
0.40
9.01
SS per m3 of effluent
           In direct process  (2)  in  which the pH value was set at 9.0
             2+
      with Ca    set at 60 mg/lit., the SS volume was  reduced, but the
      phosphate  concentration in  the effluent remained almost the same
      as direct  process (1), making  dephosphorization astable as with
      direct process CD•
                                   306

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                                                          2+
           Unless  decarbonation is performed, carbonates  degrade
      dephosphorization efficiency regardless of  the  pH value and Ca*
      conditions.
5.2.3 Effects of carbonate ions in the liquid upon  dephosphorization
      reaction
           Batch tests  were conducted to examine  the  effects of carbonate
      ions in the  liquid upon dephosphorization reaction.   Monopotassium
      phosphate was  added to deionized water to make  an aqueous solution
      of 10 mg/lit.  in  terms of phosphate.  Then, carbonate ions were
       added in steps over  a  range of 10 to 1,000 mg/lit.   This was
       followed by an addition  of  dephosphorization media in a powder form
       at a rate of 1,000 mg/lit.
       The mixture was stirred  for 2  to 20 hrs., and  the phosphate  ion
       concentration of  the filtrate  was measured.
            The relationship  between  the carbonate ion  injection  and
       dephosphorization efficiency was as shown in Figure  12.
      (Refer to Fig.  12)
     20      40   60  80100     200     400  6008001000
            Carbonate ion injection rate (mg/8)

Fig. 12 Effect of carbonate ioni (CO} 2") on the removal of ortho-phosphate

                         307

-------
             As carbonate ions  coexist,  it  is evident that they block
        the dephosphorization reaction.
             These experiments  demonstrated that carbonates have a severe
        negative effect upon dephosphorization, dictating decarbonation
        as a process essential  to  dephosphorization.
5.3 EFFECTS OF CALCIUM IONS
                                             2+
         With increase in the addition  of Ca  , the degree of supersaturation
    is increased thus increasing  the crystallization reaction velocity.
                     2+
    The effects of Ca   addition  upon dephosphorization were investigated
    by making use of the monitor  plant.
         The secondary effluent of the  Morigasaki Wastewater Treatment
    Plant used as an influent  for the monitor plant originally  contained
                          2+                        2+
    about 30 mg/lit. of Ca   ,  and was added with Ca   at  a rate of 0,  20,
    and 50 mg/lit. in the form of calcium chloride.  The  pH value was
    adjusted to 8.5 with caustic  soda,  and the influent was run for  about
    700 hrs.  The results were  as shown in Figure 13.   (Refer to Fig.  13)
           100
            90
         c.
         o
         S.
         a.
         a.
         
-------
         In every case, the dephosphorization efficiency decreased  over
    time,  and leveled off to an equilibrium point.
                                    2+
         Without the injection of Ca  , the reduction in dephosphorization
    efficiency was noticeable; within 400 hrs., the efficiency was  reduced
                    2+
    to 60%.  When Ca   was injected at a rate of 20 and 50 rag/lit.,  the
    larger the injection rate, the higher the ultimate equilibrium  point
                                                         2+
    of dephosphorization.   In the tests, even when the Ca   injection  rate
    was 20 mg/lit., the dephosphorization efficiency could be maintained
    at as  high a level as 80%.
5.A EFFECTS OF pH
         A liquid containing phosphate was adjusted to various pH values,
    added with dephosphorization media in a powder form, and  stirred
    for the purpose of conducting batch tests to  investigate  the effects
    of pH value on dephosphorization.  The results were as  shown in
    Figure 14.  The dephosphorization efficiency  increased  with  increase
    in the pH value; in the tests, the maximum  dephosphorization efficiency
    was achieved at a pH value of around 9.0.  (Refer  to Fig.  14)
         100
         80
       2
       2 60
       o
       2
       g
       9- 40
         20
\
•
0
HC03-
[mg/e]
40
1080
P043-
[mg/S]
9.0
9.0
Ca2+
[mg/£]
80
80
Dephosphorization agent injection rate
1,000 mg/lit.)
(Agitated 1 hr. by a magnetic stirrer; pH-stat
used; vacuum filtered through (GF/F))
                      8.0
9.0
                                             pH
10.0
                Fig. 14 Effect of pH value on ortho-phosphate removal rate
                                   309

-------
         When a large amount of carbonates was contained in the  liquid,
    the dephosphorization efficiency reduced in a high pH range,  demonstrat-
    ing that the carbonates have an overpowering effect upon  the
    dephosphorization efficiency.
5.5 EFFECTS OF OTHER IONS
                         -             2-
         The effects of F , Cl  and SO,   were investigated according  to
    batch tests.  The relationships between the anion injection  rates  and
    dephosphorization efficiency were as shown in Figure 15.
    (Refer  to Fig.  15)
                               50      100      200
                          Chemical injection rate [mg/8]
500
 Fig. 15  Effect of sulfate ions, chloride ions and fluoride ions on the removal of ortho-phosphate

    It was found that these anions have little  effect upon  the  dephosphori-
    zation reaction in the contact crystallization process.
5.6 EFFECTS OF WATER LOADING  (SV)
         The effects of the change in the flow  rate  of  influent upon the
    dephosphorization efficiency of the contact crystallization process
    treating the secondary effluent of the  waste  water  treatment plant
    were investigated,  In the pilot  plant,  the  space  velocity was set at a
    constant value of about 2.5 tiraes/hr.   In the practical plants, however,
    the space velocity is changeable.  Thus,  the  tests  were conducted with
    respect to space velocities of 2.5, 5.0 and 10.0 times/hr.  for a runn-
    ing time of 700 hrs., to  investigate the  effects of water loadings
                                    310

-------
     upon the dephosphorization efficiency.  The results were as shown  in
     Table 13.  (Refer to Table 13)

                           Table 13 Influence of water loadings
Space velocity
(SV = 1/hr.)
2.5
5
10
Mean value of total phosphate concentra-
tions in the effluent
(mg/8 as P)
0.32
* 10.16 ~ 0.45)
0.34
(0.19 ~ 0.57)
0.53
(0.20 ~ 0.86)
Mean value of phosphate
removal rates (%)
85.9
84.7
74.5
           * The values in parentheses show the range from the minimum to the maximum value.

          When the space velocity was set at a design value of  2.5,  the
     phosphate concentration in the effluent was held low, and  dephosphoriza-
     tion could be carried out  stably for an extended period.   But when  the
     space velocity was set at  5.0, the phosphate concentration in the
     effluent changed over a wide range detrimental to dephosphorization,
     though its average was almost the same as when the space velocity was
     2.5.
     When the space velocity was set at 10.0,  the phosphate  concentration
     in the effluent increased unfavorably.   It was thus  concluded  that
     the space velocity can be increased to twice the design value.
6.  SUMMARY
        The results of the two and a half year study are  summarized  below.
 (1)  The contact  crystallization process has a dephosphorization  efficiency
     comparable to the aluminum sulfate coagulation sedimentation process.
 (2)  The contact  crystallization process is practically stable  and  easy
     to operate.
 (3)  The amount of sludge generated is practically negligible.
 (4)  The contact  crystallization process necessitates the decarbonation
     process.
 (5)  The contact  crystallization process is superior to the  coagulation
     process from the economic viewpoint if the disposal  of  sludge  is to
     be considered.
                                      311

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-------
                                   Eighth US/JAPAN Conference

                                           on

                                   Sewage Treatment Technology
ADVANCED TREATMENT PROJECT
                    FOR
    EUTROPHICATION CONTROL
              IN LAKE BIWA
                 October 13-14, 1981

                 Cincinnati, Ohio USA
   The work described in this paper was not funded by the
   U.S. Environmental Protection Agency.  The contents do
   not necessarily reflect the views of the Agency and no
   official endorsement should be inferred.
         Kazuhiro Tanaka

         Section Chief,

         Research and Technology Development Division,

         Japan Sewage Works Agency




                       313

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1.    OUTLINE OF LAKE BIWA

          Lake Biwa, located in the Kinki  area,  one of the industrial and
     cultural centers in Japan, is the  largest lake in Japan.   Its surface
     area is 674 Km , or about one-sixth of the total area of Shiga Prefecture
     in which the lake exists,  and is about 1/120 as large as  Lake Superior
     bordering on both the United States and Canada.
          Lake Biwa has a storage capacity of about 27,500 million m , or
     about 80 years' worth of drinking  water for 3 million people in Osaka
     City.
          It is not clear when the lake was born, but it is said that the
     lake may have been created b^ a major crustal movement about 4 million
     years ago.
          Lake Biwa consists of North Lake and South Lake, and is said to
     have been named after the "Biwa",  a traditional Japanese  stringed
     instrument,  which it resembles.
          Lake Biwa receives no less than  437 major rivers, but empties
     into the Seta River alone.  Really, Lake Biwa is a natural dam.
          The water running into the lake  is conveyed by complex currents,
     mixed with lake water, and empties into the Seta River on the south of
     the lake after 10 to 15 years of detention.
          Table 1-1 shows the principal particulars of Lake Biwa.
                                     314

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                   Table 1-1  Outline of Lake Biwa
Area
Circumference
Water depth


Storage capacity
Water temperature

Catchment area
Annual rainfalls


Annual discharge


673.9 km2
235 km
Max.
Avg. North lake
Avg. South lake
103.58 m
43.0 m
4.0 m
27,500 mil. m3
Max.
Min.
27°C
6°C
3,848 km2
Max.
Min.
Avg.
Max.
Min.
Avg.
2,656 nun
(in 1896)
1,352 mm
(in 1939)
1,920 mm
(in 1894^1967)
9,100 mil. m3
(in 1896)
3,000 mil. m3
(in 1939)
5,300 mil. m3
(in 1896^ 1939)
     The functions of Lake Biwa as a water resource are manifold as
summarized below.

(1)   Water source
          With its ample yet stable supply of water unaffected seasonally,
     Lake Biwa is vital to the 13 million citizens living in the Kinki
     area.  Fig. 1-1 shows the water uses of Lake Biwa.
                                     315

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£
m
o
                       23.65m3/s
                        No.l canal
                           8.35


































1
2
3
6

mVs
41.97
15.20
16.30
30.00

Yodo River











1
2
3
4
5
ill / a
12.96
0.19
1.36
0.49
16.70
13.91
12.71
No . 2 canal
15.30
Lake
Biwa
V

Ebisugawa ^
Power
i- Station
>
'«
fl
g Sumizome %
2 Power
2 Station
Uji
Kizu
River



River
• 'V

7i
"3 / Seta Rive
« / Weir
1 /

-------
      (2)  Fishing grounds
               About 40 species of freshwater shellfish and about 60 species
          of  freshwater fish inhabit Lake Biwa.  In fact, Lake Biwa is a
          natural freshwater aquarium.
               Commercial catches of freshwater products amount to severa-1
          thousand million yen a year.  95% of freshwater pearls are exported
          to  the Middle and the Near East and other countries.  In addition.
          Lake Biwa accounts for about 70% of young sweet fishes distributed
          throughout the country.

      (3)  Energy source for hydropower station
               There are five hydropower stations using the water from
          Lake Biwa.

      (4)  Tourist resources
               There are many prehistoric remains around Lake Biwa, which
          together with beautiful scenes of the lake attract visitors
          throughout the year.

      (5)  Subject of academic study
               Lake Biwa is said to be the third or fourth oldest lake in
          the world.  It has a complex geological structure, and sinks about
          2 mm every year.
               Lake Biwa is a treasure-house of animals and plants, and
          its floor contains relics of the prehistoric ages.  Accordingly,
          Lake Biwa is treasured as a subject of academic studies.

          As Lake Biwa is playing an important role as a water resource,
     the central Government instituted the Lake Biwa Comprehensive Development
     Project in 1972 for the purposes of water quality conservation,  pro-
     tection of the natural environment,  flood control, effective use of water
     resources, etc.

2.    EUTROPHICATION IN LAKE BIWA

          From around 1965,  the water quality of Lake Biwa started to deterio-
     rate.  In 1972 to 1973,  Lake Biwa's water quality was critical.   Since
     then, the lake has been reeling between short recovery and relapse.
     Table 2-1 shows the morbid changes of Lake Biwa due to eutrophication.

                                    317

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Table 2-1  Transition of Lake Biwa
OJ
1— >
03
Stage
I
II
III
IV
V
VI
Year

Latter
half of
1950 's
First
half of
1960 's
First
half of
1960 's
Latter
half of
1960 's
First
half of
1970 's
Latter
half of
1970 's
North
lake
South
lake
1955 to 1963
1955
to
1963
1955
to
1960
1959 to 1966
1960
to
1966
1959
to
1963
1962 to 1968
1964
to
1968
1962
to
1968
1967 to 1971
1967
to
1970
1967
to
1971
1970 to 1975
1970
to
1974
1971
to
1975
1972 to ^
Symptoms
Clean and clear
Pollution set in.
Pollution
progressed.
Bottom quality
also got fouled.
Pollution
aggravated
violently.
Pronounced pollu-
tion; worst water
quality recorded.
Remarkable
pollution
Morbidity and
troubles
nil
Failure of filter
Frequent filter
trouble. Decline
of Corbiculdae.
Trouble of city
water filter
system; smelly
Decline of tourist
population.
Spread of odors.
Further decline
of shellfish.
South lake bathing
beach closed. Red
tides developed.
Remarks


P loading reached
a critical level.
Closterium
proliferated.
Pollution apparent
to the majority of
Shiga citizens.
Staurastrum
proliferated.
Wide-spread
concern over
environmental
problems .
Most of Shiga
citizens had grave
concern about the
lake pollution.
Estimated water quality
T - N
mg/£
0. 15
^0.20
0.17
^ 0.23
0.18
^ 0.24
0.20
^ 0.26
0.20
'•• 0.25
South 0.23
lake (%0.32
in 1975
0.28
South lake
(0.33)
T - P
mg/5,
0.004
^ 0.007
0.005
% 0.010
0.006
^ 0.010
0.009
^ 0.013
0.009
^ 0.012
South 0.010
lake (^0.016
in 1975
0.010
South lake
(0.015)

-------
      In Stage I, the water was still comparatively clear, and the
 phytoplanktons were changing from Diatomeae to Closterium.  No
 particular evil symptoms were found, and the north lake showed
 T-N of 0.15 to 0.20 mg/fc and T-P of 0.004 to 0.007 mg/1.
     In Stage II, the pollution set  in.  Closterium bloomed on and off,
clogging up the  filter system  for the city water.
     The north lake showed T-N of 0.17 to 0.23  mg/Jt,  reaching nearly
the critical level of eutrophication.  T-P was  0.005  to  0.010 mg/Jl.
     In Stage III, the pollution worsened, and  Closterium  and
Staurastrum became rampant.  As a result, filter troubles  were frequent.
In addition, the bottom quality was  aggravated, reducing DO to affect
fishery.  The Corbiculidae began to  decrease.   In the north lake, T-N
rose a little to 0.18 to 0.24  mg/£  from  the  level  in  stage II, but
often exceeded 0.20 mg/H.  T-P was in the range of  0.006 to 0.011 mag/A.
     In Stage IV, the water pollution was exacerbated further, and became
apparent to more than half of the people living in Shiga Prefecture.
Closterium was overwhelmed by Staurastrum, and  NOa~-N increased in
both the surface and bottom of the lake.
     The city water filter system failed frequently, and the lake water
became smelly, detracting from tha tourist value of the  lake; the
number of the tourists visiting the  lake began  to fall, accordingly.
In the north lake, T-N became 0.20 to 0.26 mg/A., and T-P  0.009 to
0.013 mg/fc.  On the other hand, the  south lake  registered  T-N  of  0.21  to
0.29 mg/fc and T-P 0.009 to 0.011 mg/t.
     In Stage V, the water pollution became pronounced, and was accompanied
by a high incidence of filter troubles and complaints lodged against foul
tap water.  Anomalous growth of Diatomeae and Chlorophyceae was seen on
and off.
     In the north lake, T-N was in the range of 0.2 to 0.25 mg/2,.
while T-P was in the range of 0.009  to 0.012 mg/Jl.  On the other
hand, the south lake showed T-N of 0.23 to 0.32 mg/£  and T-P of
0.010 to 0.016 mg/£.
     In Stage VI, the water pollution was visibly quite clear.  Pre-
dominant among the phytoplanktons was Pediastrum.  Red tides occurred,
and part of the bathing area in the  south lake  had to be closed.
Fig. 2-1 shows the zones affected by red tides  in May to June, 1977
to 1978.
                                     319

-------
Fig. 2-1 (a) Major red tide affected zones during
             the period from May to June, 1977
                      320

-------
Pig. 2-1 (b)  Major red tide affected zones during
              the period from May to June, 1978
                     321

-------
     In 1977, the red tides were seen at twenty-one places,  and in
1978 they spread to thirty-nine places.
     Table 2-2 shows estimated N-and P-loadings in the catchment area
of Lake Biwa.
         Table 2-2   N-  and P-loadings  generated  in  the
                    catchment  area  of  Lake  Biwa
                                                                    (Kg/day)
5^
\
North
lake
South
lake
Lake
Biwa
N
1960
12,627
2,336
14,963
1965
13,370
2,493
15,863
1970
15,342
3,673
19,015
1975
16,875
4,579
2i,454
1980
19,397
5,797
25,194
1985
21,429
7,227
28,656
P
1960
778
229
1,007
1965
1,187
352
1,539
1970
1,804
696
2,500
1975
1,716
613
2,329
1980
2,096
822
2,918
1985
2,481
1,058
3,539
                                             (Source:  Shiga P.G. Estimation)
     In 1980, the sources of pollution loadings were as shown in Table
2-3; domestic waste and industrial wastes accounted  for 58% of total
N-loadings and 81.6% of P-loadings, demonstrating how significant human
activities were to the pollution of the lake.

               Table 2-3  Sources of loadings in 1980
Source ^____^^
Domestic wastes
Industrial wastes
Agricultural and livestock
farming wastes
Nonpoint source
Total
N
Loadings
kg /day
8,893.5
5,719.0
4,736.5
5,845.0
25,194.0
Ratio
%
35.3
22.7
18.8
23.2
100.0
P
Loadings
kg/day
1,362.7
1,018.4
329.7
207.2
2,918.0
Radio
%
46.7
34.9
11.3
7.1
100.0
                                     (Source:  Shiga P.G.  Estimation)
                                  322

-------
     Domestic wastes was responsible for 35.3% of total N-loadings and
46.7% of total P-loadings.
     Of the P-loadings due to domestic wastes, 39% was accounted for by
night soil, 38% by phosphorus syndets, and the remainder by miscellaneous
wastes in 1975.
     Of the total generated loadings, about two thirds are expected to
enter Lake Biwa.  The relationship between these influent loadings and
plankton is as shown in Fig. 2-2.
                                   323

-------
                   [North lake]
N-
loadings
(tons/
 day)
       13
       12--
       11-
       10"
loadinc
(tons/
 day)
   1.2
             1.1-
             1.0-
             0.9-
             0.8-
   0.7
             0.6- '
             0.5- •
             0.4-
             0.3"
                      Plankton
                      sediment
                  P-
                  loadings
                                   f  N-loadings
 Plankton
 sediment
 (cc/m3)
••14
                                              "13
                                              -12
                                              -•11
                                              "10
                                              "7
                                              "5
                   1956  1961   1964   1967   1970   1974
                    to    to    to     to     to    to
                   1961  1964   1967   1970   1974   1976

                                  (Year)
           Fig. 2-2  (a)  Influent loadings vs. plankton
                                324

-------
                  [South lake]
N-
loadings
(tons/
 day)
     2.8


     2.6


     2.4-


     2.2-


     2.0


     1.8-1


     1.6


     1.4


     1.2
P-
loadincjs
(tons/
 day)


   0.4"
   0.3"
   0.2"
   0.1 •
                    P-loadings
                                 Phytoplankto:
                       •lio3
                //  ,' N-loadings
                        Phytoplankton
                        (pcs./mA)
                       •10
                  1955
                   to
                  1959
                1959
                 to
                1962
 1962
  to
 1968

(Year)
1968
 to
1971
1971
 to
1974
          Fig.  2-2 (b)   Influent loadings vs. plankton
                                  325

-------
     According to a forecast of the lake water quality based on the
estimated N-and P-loadings shown in Table 2-2, it is estimated that
in  1985, the eutrophication of Lake Biwa will be even more aggravated,
and that the north lake will show T-N of 0.31 mg/£ and T-P of 0.017
mg/£ while  the south lake will have T-N of  0.40 mg/£ and  T-P of
0.023 mg/£.
     The Shiga Prefectural Government, concerned about the situation,
promulgated in 1979 the Regulations Concerning Eutrophication Control
in Lake Biwa with a view to recovering the lake water quality to the
1965 to 1970 level, and initiated various measures against eutrophication.
     These measures were aimed to achieve the target values shown
in Table 2-4 by reducing the estimated N-and P-loadings in 1985 by about
25% and 50%, respectively.

          Table 2-4  Target water quality for Lake Biwa
                                         (mg/£)
^— -^_
North lake
South lake
T-N
0.25
0.30
T-P-
0.010
0.015
                          (Source:  Shiga P.G.)
     The implementation programs of the regulations are wide-varied.
Among them are effluent controls for the municipal wastewater treatment
plants,  works and other establishments, and the first-ever prohibition
in Japan of the use of phosphorus syndets, obtaining the attention of
the public.
     According to the effluent standards set for the municipal
wastewater treatment plants, T-N is temporarily set at 20 mg/£,
and T-P is 0.5 mg/£ for new sources and 1 mg/JJ, for existing
sources.
     As regards the phosphorus syndets, their sale and use in Shiga
Prefecture is totally banned.   In addition, the citizens in Shiga
Prefecture are also forbidden from accepting syndets as offerrings
from outside the prefecture.  The announcement of this tight control
became a controversial issue at the time.
                                   326

-------
3.    LAKE BIWA REGIONAL SEWERAGE PROGRAM

          The Shiga Prefectural Government  works out  a comprehensive Lake
     Biwa regional sewerage program in 1971,  and undertook a sewerage con-
     struction project according to the program.
          The promulgation of the Regulations Concerning Eutrophication
     Control in Lake Biwa gave an impetus to  the construction of sewage
     works indispensable for the reduction  of N- and P-loadings for which
     domestic wastes and industrial effluents are most responsible.
          According to the comprehensive Lake Biwa sewerage program, Shiga
     Prefecture is divided into five blocks - four regional sewerage systems
     and the Ohtsu municipal sewerage system.  As regards Oki Island within .
     Lake Biwa, a specific environmental protection municipal sewerage system
     has already been adopted.  An outline  of the comprehensive sewerage program
     is given in Fig.  3-1 and Table 3-1.
                                       327

-------
Ohtsu P
Sewerage1
System
                                            Hikone  and

                                              Nagahama
                                                         * Oki Island Public
                                                           Sewerage System
                                 The black dots show the location
                                 of wastewater treatment plants.
           Fig. 3-1  Comprehensive sewerage system in Shiga
                                    328

-------
                          Table 3-1  An overview of sewerage program in Shiga Prefecture
Item
Planned Service
.Area
Planned served
population
Planned treatment
capacity
Sewer system
Aggregate length
of sewers
Number of relay
pump stations
Area of treatment
plant site
Number of
municipalities
concerned
Lake Biwa Regional Sewerage System
Konan Chubu
approx .
25,500 ha
approx .
790,000
approx.
1,020,000 m3/day
Hikone and
Nagahama
approx .
12,700 ha
approx.
525,000
approx r
505,000 m3/day
Kosei
approx .
2,600 ha
approx.
250,000
approx .
120,000 m3/day
Takashima
Pending
Pending
Pending
Separate system
approx .
148 km
6
approx .
63.7 ha
5 cities and
14 towns
approx.
102 km
4
approx .
64.1 ha
2 cities and
17 towns
approx .
9 km
2
approx.
11.8 ha
1 city and
1 town
Pending
Pending
Pending
5 towns
Ohtsu Municipal
Sewerage System
approx .
1,338 ha
approx .
128,000
approx .
95,000 m3/day
Partly combined
system
approx .
283 km
3
approx .
2.9 ha
1 city
Oki Island
Municipal Sewerage
System
approx .
8.7 ha
approx .
1,000
approx .
420 m3/day
Separate system
approx .
3.5 km
2
approx .
0.2 ha
1 city
CO
INS
10

-------
          The Ohtsu municipal  wastewater  treatment  plant  has  been in  service
     since 1969,  and is now removing phosphorus  by  the  conventional activated
     sludge process combined with secondary  alum precipitation.
          Four regional sewerage  systems  are planned, each  with  a wastewater
     treatment plant.   The wastewater treatment  plant for the Konan Chubu
     sewerage system (hereinafter referred to as the Konan  Chubu Purification
     Center)  will be installed on an about 73 ha of reclaimed land on the
     shore of Lake Biwa,  and will process about  a million m  of  wastewater
     a day.  In 1977,  the reclamation work was started,  and the  construction
     of the treatment facilities  was started in  1978.
          Originally,  the treatment facilities were planned with the
     conventional activated sludge process.   As  the Regulations  Concerning
     Eutrophication Control in Lake Biwa  were established,  the design of the
     facilities was modified for  nutrients removal.  It is  expected that the
     Konan Chubu Purification  Center will start its service in 1982.
          For the wastewater treatment plant of  the Kosei sewerage system
     (hereinafter referred to  as  the Kosei Purification Center), design of
     the wastewater treatment  facilities  including  the  nutrients removal
     processes was completed in 1980, and construction  is now under way.
          Land acquisition for the wastewater treatment plant for the Hikone
     Nagahama sewerage system  is  in progress.
          A master plan for the Takashima sewerage  system is being studied.
          At Oki Island within the lake,  an  oxidation ditch having a  capacity
     of 420 m3/day is now under construction.

4.    RESERACH AND DEVELOPMENT  OF ADVANCED WASTEWATER  TREATMENT TECHNOLOGY

          In Japan, research and development of  advanced wastewater treatment
     technology started toward the end of the 1960s.
          In 1971, the Public  Works Reserach Institute  of the Ministry of
     Construction installed a  250 m3/day pilot plant  within the premises of
     the Shitamachi Sewage Treatment Plant,  Yokosuka,  about 50 miles southwest
     of Tokyo, in order to initiate a study  on a lime precipitation process
     for phosphorus removal of secondary effluent.   Since then,  the Public
     Works Research Institute  has been playing a key role for the basic
     studies of physico-chemical processes,  biological denitrification
     processes, etc.
                                         330

-------
     In 1972, the Japan Sewage Works Agency was established.  Its
Research and Technology Development Division has been promoting surveys
for the implementation of advanced wastewater treatment technology.
     In 1974, the Japan Sewage Works Agency, together with the Sewerage
and Sewage Purification Department of the Ministry of Construction, and
the Shiga Prefectural Government, constructed the Lake Biwa Advanced
Wastewater Treatment Pilot Plant with a capacity of 500 m3/day for the
purpose of studying the implementation of advanced wastewater treatment
processes applicable to the Lake Biwa regional sewerage systems.
This pilot plant was located within the Ohtsu Municipal Wastewater
Treatment Plant near the south lake of Lake Biwa.  It was composed of:
(1) alum precipitation process for phosphorus removal; (2) biological
nitrogen removal process; C3) suspended solid removal process using an
up/down flow filtration system; and (.4) dissolved organic matter removal
process using an up/down flow activated carbon adsorption column.
Given in Fig. 4-1 and Table 4-1 are the principal particulars of the
major facilities.
                                   331

-------
                                                       zee
H-
id
 to
 I---

 p
 (D
 H
 ft
 n>
 D
 rt

 tf
 H-
 H"
 O
 ft
 0)
 3
 rt
 O
  (D
  (D
  rt
                                                                                         Influent
                                                                                        (secondary
                                                                                         effluent)

Jiff
H- mm
3 .— rt HI
ua tro H,
0» *1 V-*
S O O C i
Q) X\Q (D ^
rt 1 (I> 3
0) rt
*i


I""" '




             Discharge
                                    Activated
                                    carbon ad-
                                 sorption column1

-------
                            Table  4-1   Pilot Plant Biological Nitrogen Removal Process
Process
Separate stage nitrification
in modified aeration tank
with fine sand addition
process (SSNP)
Fluidized bed denitrifi-
cation process (FBDP)
Combined carbon
oxidation-nitrification
process (CCONP)
Packed bed denitrification
process (PBDP)
Recycled nitrification-
denitrification process
(RNDP)
Reaction
Nitrification
Denitrification
Nitrification
Denitrification
Nitrification and
denitrification
Capacity (m3/day)
450
450
30
20
7
Influent
Secondary effluent
Nitrified liquor (nitrified
secondary effluent)
Primary effluent
Nitrified liquor (nitrified
secondary effluent)
Primary effluent
co
•U)
CO

-------
         The main purpose of the pilot research was to identify the phos-
    phorus removal and denitrification processes feasible for eutrophication
    control in Lake Biwa and to clarify the design criteria for these
    processes.

4.1  Survey of Chemical Precipitation for Phosphorus Removal

          Chemical precipitation processes are largely classified into:
     CD  metal precipitation and C2)  lime precipitation.   Of the two, the
     metal precipitation process was  investigated because of its simple
     process formation and low capital and operating costs.
          According to laboratory tests, alum was selected as a coagulant,
     arid a pilot plant was installed  to test alum precipitation treatment
     of secondary effluent.   Thus,  the design criteria for the process were
     established.

     (1)   As shown in Fig. 4-2, it is found that rapid mixing can be carried
          out thoroughly on condition that the G-value is about 100 sec
          with the detention time in  the rapid mixing tank at 5 min.  It
          is also found that flocculation is best achieved when the G-value
          is less than 50 sec."1 and  the GT-value is about 90,000.
                                     334

-------
o

0)
•H
O
•H
•w
»n
     100
      90
      80
      70
      60
O   Phosphorus
   removal
   efficiency

0 Turbidity removal

   efficiency
                                 100


                              G-value (sec.  l)
            200
            Fig. 4-2  G-value,  and phosphorus and turbidity

                      removal efficiency  (rapid mixing)
   (2)  The relationship between alum  addition  ratio and residual phosphorus

       is shown in Fig. 4-3.
                                    335

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c
oj oi
g U.I
,_!
M-l
M-l
W










0.01
• D7.0
. 7.3
7.3
n
H ®



.
.
•
.





.





Legend
D 7.1
\ P6.9
\ D6.8
El Q6. 7
7.2 y D7-0
nn _
7. ID U7.2H 6.8
• • \ n
7.3 7.3 \
H _ \ H °6.6
H \ EJ
\ "3 H ft6'9
H «7.2\ 7'3 Tl 6.7
H \
O Q6.8 ta
6'6 . "\
\
7.2 \
\
• \-i06-e
7-1 6'9 ^oe s
6.6 O6-5
\
o d\p.
6.4 6.4 \'
\
06.2
Japan Sewage Works Agency ( Influent POij-P
O concentration, 0.51 to 1.24 mg/£.)
g Kobe City (blanket ^
type Sed. tank) (Influent POi»-P














A 6.9

AO5'5
7.0



\
\
A\ A 7.2
7.2 \
D Kobe City (blanket L concentration, O \
type clarifier) 0>72 to 4-00
H Kobe City (blanket mfT/o \
type clarifier filtrate) J my/*-/
5-5\A6.9
6.3 \
A Osaka City (Influent POi»-P concentration, 7.1 ^ \A-7i



0.22 to 0.89 mg/£.)
7.2 \ •"
A7.2 \7 ,


Suffix sh<

DWS pH value .

AA A
7.0\ 6.9


0-5 1 234 10 234
                     -P mol ratio
Fig. 4-3  AVPO^-P mol ratio and  effluent  POi»-P
                   336

-------
     In Fig. 4-3,  the results of pilot plant tests conducted in Osaka
     City and Kobe City are also plotted.  From the figure, it is found
     that it is generally possible to reduce the concentration of POi»-P
     in the effluent below 0.5 mg/SL if the A&/POi»-P mol ratio is
     3 or larger.   It ia also found that the addition of anionic polymer
     as a coagulation aid at a rate of 0.2 to 0.3 mg/Jl improves the
     flocculation  rate and results in the improvement of the phosphorus
     and turbidity removal efficiencies by about 23% and 90%, respectively.

(3)   It is found that the phosphorus removal efficiency can be increased
     by returning  the sludge from the sedimentation tank to the floccu-
     lation tank as illustrated in Fig. 4-4.
                                     337

-------
 Detention time

    5 min.
                        Secondary effluent,
                         500 m3/day
                V    tank    /
   30 min.
                               approx.  350 £/min.
Flocculation tank
  140 min.
              Sedimentation tank
LV, 200 to
400 m/day
 Rapid filtration
      column
                                           o
                                     Return
                                     sludge pump
                                           O
                                p  j  Sludge
                                     withdraw pump
                                          Sludge
                                          thickener
           Fig.  4-4   Return of alum-precipitated  sludge
                               338

-------
     The optimum condition of sludge return is that the return  sludge
     ratio is 5%, and the concentration of return  sludge is  2,000  to
     3,000 mg/Jl.

 (4)  It is found that the phosphorus concentration in  the effluent can
     be further reduced when the alum-precipitated sludge is returned
     to the flocculation tank after its pH value is conditioned with
     sulfuric acid to about 3.5.  The effect of returning the acid-
     treated sludge is as shown in Fig. 4-5.
=>*
\
£
 I
o
G
0)
a
w
      1.0 -
      0.50-
      0.10 -
      0.05 -
      0.10 -
-O	  No return sludge
-O—  Return sludge
-•	  Acid  treated return sludge
          1.0       2.0      3.0      4.0    '  5.0
                           A&/P  mol ratio
         6.0
              Fig. 4-5  Effect of acid treatment of
                        alum-precipitated  sludge
                                     339

-------
          In addition to the surveys referred to above,  at the pilot plant
     the precipitated sludge was investigated as to its  generated volume,
     characteristics, settling,  thickening and dewatering abilities, etc.
     A study was also carried out for the potentiality of sludge as a
     construction material,  and the sludge subjected to freezing, melting
     and then dewatering by filter press proved that it is applicable as a
     roadbed material in terms of soil mechanics.

4.2  Survey of Biological Nitrogen Removal

          The biological nitrogen removal process can potentially remove
     all forms of nitrogen,  but has the following problems.

     (I)  The biological process is lower in reaction rate as compared
          with the physico-chemical process, and is liable to be influenced
          by water temperature.

     (2)  The alkalinity of sewage in Japan is, in general, lower than
          that of the sewage in the United States and Europe.  Thus, it
          is often necessary to inject an alkaline agent for the purpose
          of conditioning the pH value in the nitrification process.

     (3)  For the denitrification process, it is necessary to inject
          methanol as a hydrogen donor.

          Taking account of these problems, the five biological nitrogen
     removal processes listed in Table 4-1 were selected and subjected to
     pilot plant studies.

 4.2.1  Separate Stage Nitrification in Modified Aeration with Sand Addition
        Process  (SSNP)

             In this process, fine sand  (^ 0.15 to 0.3 mm) is suspended in
        a nitrification tank in order to grow nitrifying bacteria on the
        surfaces of sand particles for the purpose of nitrification.
        Since SSNP can keep MLVSS high and the active surface of the biomas
        is large, the nitrification rate per unit voluem of nitrification
        tank is high.
             At the Ohtsu Municipal Wastewater Treatment Plant,  secondary
        effluent was experimented with by running a turbine blade type mixing
                                     340

-------
nitrification tank  (hereinafter referred to of nitrification
tank with mechanical mixer) and a nitrification tank with air
lift in parallel for the purpose of investigating the
nitrification rate  and process stability, etc.
     Fig. 4-6 shows flow diagrams of the two pilot plants.

     The nitrification tank with mechanical mixer and the nitrification
tank with air lift were operated under the same loading conditions for
the purpose of comparison.   The results are as shown in Fig. 4-7.
                                  341

-------
                                                                                 PHIC
     AIR
Influent
                                                                      Nitrification tank

                           Fig. 4-6 (a)  Nitrification tank with mechanical mixer  (450 m3/day)
                                                                                                         NaOH storage
                                                                                                         tank
                                                 Influent  storage  tank

-------
             Influent storage
                  tank
NaOH
tank
Influent
                                                      PHIC
                                                                Effluent
                                                              V=318 Si
                      Fig.  4-6 (b)   Nitrification tank with
                                    air lift (20 m3/day)
                                      343

-------
 L)
 o
 0)
 M
 3
 (D
 -P
 0)
 4J
        JO
        20
        10
5000



4000



3000



20OO



1OOO







  80



  70


  60



  bO



  40


  30



  20



  10
                                                                                                Onjanic natter

                                                                                                Injection
                                         _L
                                                            _L
                                                                                          _L
 T
w
w
Nov.  1    Nov. 10  Nov.  20   Itov. 30   Dec. 10   Dec.  20   Dec. 30     Jan.  1O  Jan. 20



    O '  Nitrification  tank with mechanical mixer



    n '  Nitrification  tank with air lift
                                                                                                  Jan
                                                                                                       30   Feb. 10   Feb.  2O  Mar. 1    Mar.  10
                                                                                _L
                                                                                          J_
           Nov.  1
                     Nov.  10  Nov.  20  Nov. 30   Dec.  10   Doc. 20   Dec. 30
                                                                              Jan.  1O  Jan. 20     Jan
                                                                                                       30   Feb. 10   Feb.  2O
0)
-p
It!
c
o
•H
4J

-------
It was found that the volume of biomass to be kept in the nitrifi-
cation tank varied depending on the type of mixing.  In about two
months and a half after the start of operation, the MLVSS in the
nitrification tank with air lift became as large again as that in
the nitrification tank with mechanical mixer.  As a result, the
volumetric nitrification rate became about 30 g/m3/h in the nitri-
fication tank with air lift, or about twice as high as about 15
   ^
g/m /h in the nitrification tank with mechanical mixer.
     On February 1, a test was started to investigate the effect
of the concentration of organic matter on a nitrification rate.
For this purpose, a solution of meat extract was injected into the
influent to have a BOD concentration of 20 mg/£.   (The influent
BOD before conditioning was about 11 mg/£).  By the addition of
organic matter, the MLVSS in both tanks tended to rise, and the
nitrification rate rose as well.  On March 2, the MLVSS in the
nitrification tank with air lift was about 4,300 mg/fc or about
2.6 times as much as that in the nitrification tank with mechanical
mixer, and the nitrification rate in the nitrification tank with
air lift was about 70 g/m3/h,  or about 4.6 times as much as that
in the nitrification tank with mechanical mixer.
     In the nitrification tank with mechanical mixer,  the growth
of nitrifying bacteria on the sand particles was largely governed
by the turbine blade speed, and the count of nitrifying bacteria to
be kept and the nitrification rate were found smaller as compared
with the nitrification tank with air lift.  At a water temperature
of 20°C,  the nitrification rate in the nitrification tank with air
lift was  about 60 g/m3/h,  which was higher than in any other
nitrification processes in Table 4-1.   But, the nitrification tank
with air  lift was found destitute of stable performance on a long-
term continuous running basis.
     The  future study includes the controlling procedures of the
nitrification capacity, and measures for protecting the nitrification
tank from sand abrasion,  optimum aeration system,  and' mixing
intensity.
                                 345

-------
4.2.2  Fluidized Bed Denitrificatio'n Process  (PBDP)

            When sand (0 0.47 to 0.59 mm)  is  fludized in a reactor  by the
       upward flow of nitrified liquor while  injecting methanol,  denitri-
       fying bacteria grow on the surfaces of sand particles to form
       pellets.
            In the FBDP, the reactor is free  from clogging since the
       pellets are fluidized, and a high denitrification rate can be
       achieved.   Fig.  4-8 shows a flow diagram of the pilot plant.
            Table 4-2 shows an example of the performance of the FBDS in
       stable operation.
                                                                Sludge
                                                           Reactor
                                                           (pellet-growth part)
                                                                   Fluidized
                                                                   sand
                                                                    (pellet
                                                                     forming)
                                        Fluidized bed  column
                      Fig.  4-8  Flow diagram of FBDP
                                       346

-------
                                      Table 4-2  An example of FBDP operation
Date
Feb. 2,
1978,
Morning
Feb. 2,
1978
Afternoon
Water
temperature,
°C

13.0

13.5
Plow
rate
(mj/day)

432

432
Sand
size
(mm)

0.47

0.47
I/
Methanol
ratio
(-)

5.5

4.3
N- load ings
(kg/raVday)

24.0

6.34
Denitrifi-
cation
efficiency
(%)

99.5

93.8
Denitfiri-
cation
rate
(g/m3/h)

99.5

248
Bioraass
(VSS-kg)

20.3

20.3
Influent
(NO ~+NO ~)
(mg/£)

11.24

29.83
Effluent
(NO ~+NO -)

-------
      Fig. 4-9 shows the  changes in NO2~N and  N03~-N in the fluidized
      bed referred to in  Table 4-2.
30 Jr
                                                      Morning
                                                      Afternoon
                              Time (min)
       Fig. 4-9  Changes of  (N02  + NO3  )-N  in  the  fluidized bed

      The morning data showed a small nitrogen  loading  of 2.4 kg/m3/day,
      and the denitrification was completed  in  about  3  min.  at a denitrifi-
      cation efficiency of 99.5%.
           In the afternoon, the nitrogen loading was about  2.6 times the
      morning value to 6.34 kg/m3/day.   In this  case, the denitrification
      efficiency was 93.8% with the detention time  of about  7 min.,  and
      the denitrification rate was as large  as  248  g/m3/h. •  In order to
      maintain such a high denitrification rate, it is  necessary to  draw
      grown pellets out of the column top, remove the biological
      encrustations from sand particles  and  return  the  naked sands to the
      fluidized bed.  The pellet withdrawal  rate was  set at  about 20 to 25%

                                   348

-------
       of the influent flow rate.   It was found that the pelletizing in the
       bottom of the fluidized bed could be promoted when sands were
       returned with incomplete removal of the encrustations.
            In a steady state, the biomass to be held in the fluidized
       bed was about 20 kg-VSS, or a 1.2% concentration.  In this case,
       the sand was about 200 kg (12.6%).
            It was demonstrated by the pilot plant tests that the FBDP is
       10 to 100 times faster in denitrification rate than the packed bed
       devitrification process (PBDP) and recycled nitrification-
       denitrification process (RNDP).
            However, such important operation factors as the expansion ratio
       of sand and pellets, the degree of the biomass removal from sand,
       and biomass removal method, stability against loading changes, etc.
       could not be investigated thoroughly, and it was judged that the
       FBDP should be further upgraded.

4.2.3  Combined Carbon Oxidation-Nitrification Process (CCONP)

            The CCONP is a process in which the oxidation of organic matter
       and nitrification of NHi, -N are carried out in one aeration tank.
       The CCONP was tested using  a pilot plant fed with primary effluent
       of the Arakawa Wastewater Treatment Plant adjoining the Research
       and Training Center of the  Japan Sewage Works Agency.  The pilot
       plant was run continuously in order to investigate the relationship
       between SRT and nitrification efficiency, process stability, etc.
       Table 4-3 shows a summary of the operation results of the CCONP.
                                      349

-------
                                         Table 4-3  Running results of CCONP
No.
1
2
3
4
5
6
7
8
9
10
11
12
Test
period
Dec. 7, 1977
to Jan. 23
1978
Jan. 26 to
Feb. 7
Feb. 9 to
Feb. 16
Mar. 13 to
Apr . 7
Jun. 15 to
Jun. 26
Jul. 3 to
Jul. 21
Aug. 10 to
Aug . 28
Sep. 20 to
Oct. 4
Oct. 6 to
Oct. 30
Nov . 6 to
Nov. 22
Nov. 30 to
Dec. 19
Feb. 6 to
Feb. 16,
1979
Flow
rate

-------
The tests were started in winter with the detention time set at
12 hrs.  With the rise of water temperature, the detention time was
reduced; in summer, the pilot plant was run with the detention time
set at  3 hrs.  Later, in the period from autumn to winter, the
detention time was set at 4 hrs.  Throughout the test period, the
nitrification was carried out stably with a nitrification efficiency
of 98%  to 100%.  Although it is claimed that, in winter when water
temperature is low, stabilized nitrification is difficult unless
the detention time is extended to a certain degree, it  is  found  from
Table 4-3 that a practically high nitrification efficiency can be
achieved with a detention time of about 4 hrs. even in winter if
the operational conditions (SRT, MLSS, etc.) are set properly.
     Fig.  4-10 shows the relationship between SRT and water temper-
ature for the data representing a nitrification efficiency of 95%
or more.
                                 351

-------
                     30.0
                     24.0  -
                     18.0
en
ro
                 n!
                 13
                     12.0  -•
                     6.0  -
                     0.0
                         0.0
                                                                    u   0.18 expl0.116(T~15)
• ••      •  ^v.         ••       •
 •       •     ^-^  ••   •   •  ••
                                             6.0                12.0               18.0

                                                                 Water temperature (°C)

                                                   Fig. 4-10   SRT vs. water temperature
                                                                                                      24.0
                                                                                                                          30.0

-------
       The solid line in the figure shows the reciprocal of the maximum
       growth rate, p, of nitrosomonas determined by Downing, et al.
       The greater part of the SRTs measured is above the reciprocal of y
       calculated from the formula established by Downing, et al., suggesting
       that the SRT necessary for keeping nitrosomonas in the aeration tank
       can be determined by that formula.
            The nitrification rate was about 2.5 g/m3/h at a water temper-
       ature of 10°C and about 5.4 g/m3/h at a water temperature of 20°C.
       Where the nitrification efficiency was 95% or more, the BOD loading
       was 0.05 to 0.1 kg/kg-MLSS/day at a water temperature of 10°C and
       0.15 to 0.25 kg/kg-MLSS/day at a water temperature of 25°C, and was
       smaller as compared with the conventional activated sludge process.
       The test Nos.  1 through 4 refer to the case where the settling time
       in the final sedimentation tank was 1.2 to 2.3 hours.  The effluent
       showed 5 to 10 mg/fc in BOD, 9 to 12 mg/£ in COD and  13 to
       15 mg/£ in SS, attaining a practical high efficiency of organic
       matter removal.  The tests Nos. 5 through 12 refer to the  case where
       the settling time was as short as 0.8 to 1.1 hour; because of SS
       carryover,  the effluent quality was degraded a little.  The alkalinity
       of the influent was about 130 mg/£, and caustic soda of the amount
       equivalent to an alkalinity of 50 to 90 mg/i was  injected  into
       the aeration tank for the purpose of conditioning the effluent pH
       value to about 6.5 to 7.3.
            Finally,  it was found that the CCONP could be run stably at a
       nitrification efficiency of more than 95% when the SRT,  MLSS
       concentration and pH value were set appropriately.

4.2.4  Packed Bed Denitrification Process CPBDP)

            When nitrified secondary effluent is .run downward with the
       addition of methanol through a filtration column stuffed with sand
       of 3 to 5 mm in diameter, it is denitrified by the denitrifying
       bacteria grown over the surfaces of the sand particles in the
       filtration column.   The PBDP dispenses with sedimentation tank
       and sludge return operation,  and can remove SS by filtration.
            A 20 m3/day pilot plant was employed for tests.   Its flow
       diagram is as shown in Fig.  4-11.
                                     353

-------
                           Aeration tank
Sedimentation tank
Packed bed
denitrification column
    Influent
     (primary effluent)
                      NaOH
oo
en
             Air
                                                                                 Methanol
                                                           n
                                                                 P—©
                                                                     Air     	
                                                                      (for
                                                                      backwas hi ng)
                                                                                                            Effluent
                                           Return  sludge  pump
                                   Backwash pump
                                         Fig. 4 11  Flow diagram of CCONP and PBDP

-------
The packed bed (700 x 700 by 5,500 H) was stuffed 1.8 m deep with sand
of 2 to 4 nun size over a gravel layer (6 to 20 nun & x 400 thick) .
The influent used was the nitrified effluent from the CCONP.
Namely, the CCONP and PBDP were combinedly operated continuously
for the purpose of studying the denitrification rate, SS removal
efficiency, and overall nitrogen removal efficiency, etc.
     Table 4-4 shows a summary of the operation results of the
PBDP.
                                 355

-------
Table 4-4  Running results of PBDP
No.
1
2
3
4
5
6
7
8
9
10
11
Test
period
Jan . 20
to 31,
1978
Feb. 1
to 17
Mar. 1
to 31
Apr. 1
to 28
Jul. 24
to 28
Aug. 12
to 28
Oct. 6
to 31
Nov. 1
to 26
Dec. 1
to 20
Jan. 29
to 31,
1979
Feb. 1
to 16
Flow
rate
(rnVday)
18.0
18.0
18.0
18.0
29.0
29.4
29.4
29.4
29.4
18.7
18.7
Detention
time
(min. )
70.4
70.4
70.4
70.4
43.7
43.1
43.1
43.1
43.1 •-,
67.8
67.8
Water
temperature
(°C)
7.8
8.2
10.5
14.7
28.2
29.1
19.1
17.0
13.2
9.9
12.0
N-
loadings
(kg/raVday)
0.502
0.471
0.404
0.369
0.582
0.760
0.690
0.810
0.870
0.490
0.502
Volumetric
loadings
(mVmVday)
36.7
36.7
36.7
36.7
59.2
60.0
60.0
60.0
60.0
. . 38.2
38.2
Methanol
ratio
(-)
3.8
4.0
5.0
5.6
4.5
3.3
3.9
3.4
2.6
3.4
3.5
Denitrifi-
cation
rate
(g/m3/h)
19.8
16.8
15.5
14.8
24.9
31.0
28.5
31.3
32.4
19.3
20.5
Denitrifi-
cation
efficiency
(%)
94.7
87.9
91.9
94.5
98.3
97.4
99.0
93.4
88.5
92.6
96.6
Effluent
BOD
(mg/£)
4.1
6.6
14.9
14.8
-
-
6.6
3.6
11.4
13.9
4.5
Effluent
COD
(rog/£)
10.9
12. a
14.8
15.3
16.2
10. 1
8.8
8.8
13.1
11.8
9.2

-------
 The volumetric Loading was set in two stages:   In winter,  the
 volumetric loading was set at 37 to 38 m3/m2/day and the detention
 time at 68 to 70 min;  and in summar,  the volumetric loading was at
 59 to 60 m3/m2/day and the detention  time at 43 to 44 min.
      The tests Nos. 1,2,3 and 10 refer to data obtained when the
 water temperature was as low as 7.8 to 10.5°C and the influent NOs -N
 concentration was between 20 and 25 mg/£, but  the NO3 -N and NO^  -N
 concentration in the effluent were 0.1 mg/H to 1.2 mg/£ and 0.7 to
 1.6 mg/£ respectively, achieving as high a denitrification efficiency
 as 88 to 95%.
      When the water  temperature  rose  above 10°C,  the  denitrification
 efficiency improved  further;  with  the exception of test  No.  9,  the
 denitrification  efficiency was  93  to  98%.   Test No.  9 showed a
 denitrification  efficiency of 88.5%,  a little  lower than other  tests,
 and this may  have been attributable to the fact that  the methanol
 ratio was as  low as  2.6.
      The denitrification  rate was  6.67 g/m3/h  at  10°C and 29.2  g/m3/h
 at  20°C.   The packed bed  as a filter  showed an SS  removal efficiency
 of  85 to 97%  at  a volumetric loading  of 37 to  97 m3/m2/day,  and
 the effluent  SS  was  2  mg/£.
      The nitrogen gas  generated  by denitrification was removed  by
 backwashing the  filter at a water  flow rate  of 0.32 m3/m2/min.
 once  every 2  to  4 hrs.
      And the  filter  was backwashed in  a mode of  (air  agitation,
 2 min. + air  and  water backwashing, 10  min.  +  water backwashing,
 3 min.)  every 3  to 3.5 days  in case of  low volumetric  loading and  every
 2.5 days in case of  high  loading.
      The overall T-N removal efficiency of the combination
of  CCONP  and  PBDP remained  85% when the water  temperature was as
low as 8°C and when  the methanol ratio was as  low  as  2.6.
In other  cases, the  T-N removal efficiency was 90  to  95%; T-N in
the effluent was  2 to  3 mg/& as against about  30 rag/A in the
influent.
     PBDP requires the addition of methanol as a hydrogen donor, but
exhibits a stable, high denitrification efficiency.   In addition,
it dispenses with the independent  filtration process.  All these
features have been demonstrated by the pilot plant  tests.

                                  357

-------
4.2.5  Recycled Nitrification-Denitrification Process (RNDP)

            In this process,  a denitrification tank and a nitrification
       tank are combined,  and the effluent from the nitrification tank is
       returned to the denitrification tank.   Namely, the organic matter
       in the influent is  used as a hydrogen donor for denitrification
       and the resultant alkalis can be used in the nitrification process.
       Therefore, methanol and alkali agent can be saved.  The tests were
       conducted using a 7 m3/day pilot plant fed with the primary effluent
       from the Arakawa Wastewater Treatment Plant in order to investigate
       the recycle ratio,  SRT, excess sludge volume and other operating
       factors.
            Table 4-5 shows a summary of the operation results of the pilot
       plant.
                                   358

-------
Table 4-5  Operation results of RNDP
CO
01
VO
No.
1
2
3
4
5
6
7
8
Test
period
Mar. 10
to Apr. 4,
1978
Apr. 5
to 28
Jun. 15
to 28
Jul. 1
to 14
Jul. 15
to 28
Aug . 10
to
Sep. 30
Oct. 1
to
Dec. 19
Jan . 17
to Feb.
16, 1979
Flow
rate
(m3/day)
9.8
9.8
10.1
10.1
10.1
9.3
9.3
14.9
Tank
capacity
(m3)
Denitri-
fi cation
3.0
2.0
2.0
2.0
2.0
2.0
2.0
1.0
3.0
Nitrifi-
cation
3.2
4.2
4.2
4.2
4.2
4.2
4.2
2.1
3.2
Detention
time
(hrs.)
15.2
15.2
14.7
14.7
14.7
16.0
8.0
10.0
Recycle
ratio
(-)
1 . 9^2 . 0
1.7VL.9
1.4
3.0
4.6
1.6
1 . 6%1 . 7
1.5
Water
temperature
(°C)
9.5
14.9
26.0
27.4
28.4
26.1
17.1
11.0
MLSS
(mg/£)
4960
4820
3600
3100
2490
2780
3680
6630
N-
loadings
(kg/m3/day)

0.044
0.059
0.055
0.056
0.049
0.096
0.074
BOD
loadings
(kg/kg-
MLSS/day)
0.025
0.023
0.046
0.045
0.047
0.041
0.061
0.035
SRT in
total
system
(days)
-
144.2
185.3
266.6
121.5
139.5
48.3
46.3
SRT in
nitrifi-
cation
tank
(days)
-
97.7
125.6
180.6
82.3
94.5
32.5
23.9

-------
                                                  Table  4-5  (Continued)
No.
1
2
3
4
5
6
7
8
Nitrifi-
cation
rate
(mg/g-
MLSS/hr . )
-
0.50
1.0
1.1
1.4
1.1
1.6
0. 7
Nitrifi-
cation
rate
(g/ra3/hr.)
-
2.37
3.58
3.35
3.37
2.90
5.60
4.85
Nitrifi-
cation
efficiency
(%)
-
91.7
99.7
99.5
99.6
99.5
95.5
86.5
Denitrifi-
cation
rate
(mg/g-
MLSS/hr.)
-
0.53
1.2
1.2
1.0
0.9
1.0
0.4
Denitrifi-
cation
rate
(g/mVhr.)
-
2.52
4.43
36.9
2.38
2.45
3.79
27.1
Denitrifi-
cation
efficiency
(%)
-
43
57
52
32
38
30.
41
T-N
removal
efficiency
(%)
-
52
59
53
34
41
35
54
Influent
BOD
(rog/fc)
79.8
69.8
101.5
84.9
72.1
69.9
72.4
95.7
Influent
T-N
(mg/£)
-
28.1
36.5
34.0
34.5
32.5
32.1
30.9
BOD/T-N
ratio
(-)
-
2.5
2.8
2.5
2.1
2.2
2.3
3.1
BOD
removal
efficiency
(%)
82.8
82.0
93.9
96.0
94.0
94.5
90.7
92.4
GJ
CTi
O

-------
         When the water temperature was as low as 11°C, the nitrification
         efficiency remained at 86.5%.   In other cases, however, the nitrifi-
         cation efficiency was more than 90%.   As the influent BOD/N ratio
         was as low as 2.1 to 3.1,  the  denitrification efficiency remained
         at 30 to 57%, and the overall  T-N removal efficiency was in the range
         of 35 to 59%.  The SRT was 24  days in winter when the pilot plant
         was run with the detention time at 10 hrs.  and 82 to 180 days in
         summer when the detention time was set at 15 hrs.  The SRT in summer
         was extremely long because little excess sludge was formed as
         auto oxidation of sludge progressed.   In winter, the BOD removal
         was degraded a little, but in  almost all cases, the BOD removal
         efficiency was more than 90%;  the BOD in the effluent was 5 to 7
         mg/£ as against 70 to 100 mg/£, in the influent.
              The nitrogen removal efficiency of the RNDP is governed by
         factors such as influent BOD/N ratio, recycle ratio, detention
         time, volumetric ratio of denitrification tank to nitrification
         tank, MLSS concentration,  and  water temperature, etc.  A mathe-
         matical model of the RDNP was  developed based on the pilot plant
         test results to identify the interrelations between these factors
         and the design and operational requirements of the RNDP.  An analysis
         of the mathematical model has  already been submitted in the form of
         a progress report.

5.    SURVEY OF RNDP IN FULL-SCALE FACILITIES

          The operating characteristics of the RDNP were clarified according
     to the 7 m3/day pilot plant tests.  A full-scale demonstration plant of
     RNDP was designed based on the test findings and began operation in
     March 1981, and the process stability, and the factors governing the
     operation and maintenance, etc. were studied.
          The demonstration plant used  was one train of the conventional
     activated sludge plant in the Arakawa Wastewater Treatment Center.
     The principal particulars of this  train are  listed  in Table  5-1.   Its
     processing capacity as a conventional activated sludge process is
     17,600 ra3/day.  In order to convert the conventional activated sludge
     process into the RNDP, modifications were made as follows.
                                     361

-------
                                  Table 5-1  Principal particulars of  experimental  train
CTl
PO

Primary sedimentation tank
Denitrif ication tank
Nitrification tank
Fore
Aft
Fore
Aft
Final sedimentaion tank
Width
(m)
4.3
9.0
9.0
9.0
9.0
4.3
Length
(m)
50.0
21.25
21.25
21.25
21.25
56.0
Effective
depth
(m)
4.0
5.0
5.0
5.0
5.0
4.45
Number of
compartments
2
1
1
1
1
2
Capacity
(m3)
1720
956.25
956.25
956.25
956.25
2143

-------
 (1)  The aeration tank was halved into fore and aft parts, and  the
     diffuser was removed from the fore part, and four units of submerged
     mixers  (15 kW x  2 units  and 11 kW x  2 units) were installed instead
     in order to form a denitrification tank.

 (2)  The aft half of  the aeration tank was used intact as a nitrification
     tank.

 (3)  A submerged pump (5,400 m3/day) was  installed in the nitrification
     tank for recycling nitrified liquor  to the denitrification tank.
     When increase of the recycling rate  was required, a standby sludge
     return pump was  operated to feed nitrified liquor, together with
     return sludge, from the final sedimentation tank back to the
     denitrification  tank.

 (4)  A system for adding methanol and alkaline agent was installed to
     provide against  the shortages of BOD and alkalinity in the influent.

 (5)  A monitoring system was installed for continuous recording of DO
     in both the denitrification tank and nitrification tank and pH
     in the nitrification tank.

     A flow diagram of the modified facilities is shown in Fig.  5-1.
The modified facilities (demonstration plant) were put into operation in
March 1981, and will  be run continuously  for one year.  In this report,
therefore, the operating results obtained for the three months  from
March till June are discussed.

     Table 5-2 is a summary of the running conditions during the said
three-month period.
                                  363

-------
      Methanol
      storage tank
NaOH
storage tank
from Primary
sedimentation
tank
              Submerged mixe,r,
                 11  kW x 2
                                     15 kW x 2
                                                               Diffuser
                                                    Sludge  return pump

                                      Fig. 5-1  Flow  diagram of full-scale  RNDP
                 c
                 4)
                 3
                                                                                             Air

-------
                                      Table 5-2  Demonstration plant running conditions

Period
Influent flow rate (Q)
(mVday)
Detention time
(hrs.)
Recycle ratio
(%)
Denitrification
tank
Nitrification
tank
Total
Return sludge
pump
Recycle pump
Total
Aeration rate (*Q)
Sludge withdrawal rate (m3/day)
MLSS (mg/Jl)
SVI
SRT (days)
Run 1
Mar. 30 to
Apr. 21, 1981
5,000
9.1
9.1
18.2
100
0
100
4.8
20^ 40
2450
(1546 ^ 3820)
114
(106 ^ 134)
26
(18 ^ 42)
Run 2
Apr. 22 to
May 13
6,000
7.6
7.6
15.2
100
0
100
4.8
20
1980
(1710 ^ 2220)
110
(97 "o 122)
33
(27 ^ 39)
Run 3
May 14 to
Jun. 8
6,000
7.6
. 7.6
15.2
100
90
190
4.8^ 8.0
20
2540
(2150 ^ 2830)
127
(112 ^ 152)
37
(19 ^ 48)
Run 4
Jun. 9 to 29
6,000
7.6
7.6
15.2
100
90
190
6.4^ 7.2
20 ^ 30
1920
(1510 ^ 2640)
120
(103 ^ 138)
20
(11 ^ 30)
CO
o>
en

-------
     Table 5-3 is an analysis of the influent  (effluent of the primary
sedimentation tank) and the effluent quality.  Of the total nitrogen (T-N)
in the influent, 60 to 70% was accounted for by NHt. -N, and the majority
of the remainder by Org-N.  N02 -N and NOs -N wore almost naught.
The BOD/N ratio of the influent was about 4, and the addition of methanol
was not carried out.
                                    366

-------
                                          Table 5-3  Quality of  influent  and  effluent




                                        Primary sedimentation tank  effluent quality (1)
                                                                                                    (mg/i)
"^\^
Run-1
Mar. 30 to
Apr. 21
Run- 2
Apr. 22 to
May 13
Run -3
May 14 to
Jun. 8
Run-4
Jun. 9 to 29
Water
temperature
15.5
(14. 4% 17.0)
16.4
(15.5%17.2)
16.6
(13.0%18.0)
18.4
<17.6%19.2)
M-alkalinity
133.0
(76.1% 146.3)
134.0
(127.0% 146.8)
129.7
(103.3% 144.8)
130.1
( 95.9%140.4)
NHi, *-N
15.8
( 8.0%20.8)
14.4
(12. 5% 16. 4)
13.1
(11. 3% 16. 2)
13.7
( 7.8%16.1)
No2~-N
N.D
N.O
N.D
N.D
No3"-N
0.08
(0.02% 0.20)
0.07
(0.03%0.12)
0.06
(0.02%0.15)
0.13
(0.02% 0.47)
T-N
22.7
(15.1%29.6)
22.3
(19.8%24.8)
21.9
(19.9% 25.4)
21.0
(13. 2% 25. 6)
Dissolved T-N
18.3
(10.8%21.3)
18.1
(14.7%19.6)
16.3
(13.0% 19.3)
17.0
(10.2% 21.2)
CO

^^\_
Run-1
Mar. 30 to
Apr. 21
Run- 2
Apr. 22 to
May 13
Run- 3
May 14 to
Jun. 8
Run-4
Jun . 9 to
29

Org-N
6.6
(6.0 % 9.2)
7.8
(6.0 % 9.8)
8.6
(6.8%10.2)
7.1
(4.2%9.4)
(mg/i)
Dissolved
Org-N
3.0
(1.9%4.8)
3.6
(1.91.6.4)
3.0
(1.5%6.1)
3.1
(1.0% 5.0)
COD
39.3
(32.5%45.2)
39.9
(33.5%45.2)
43.6
(39.3%46.2)
38.7
(28.6%47.4)
Dissolved
COD
20.7
(12.0%25.1)
20.7
(18.5% 23.0)
18.5
(16.1% 20.7)
21.8
(12.7%43.7)
BOD
80.7
(56.4%96.9)
83.6
(77.6%87.8)
92.3
(72.0% 108.5)
70.6
(50.6%86.2)
Dissolved
BOD
37.7
(22.0% 46.9)
40.2
(32.1% 46. 4)
25.9
(14.4% 45.6)
23.5
(16.3% 30.0)
SS
48
(28% 71)
53
(31%66)
84
(77%96)
49
(29% 98)

-------
                                                    Table 5-3  (Continued)


                                           Final  sedimentation tank effluent quality  (1)
                                                                                                     (mg/£)
^^-\_
Run-1
Mar. 30 to
Apr. 21
Run -2
Apr. 22 to
May 13
Run- 3
May 14 to
Jun. 8
Run -4
Jun. 9 to
29
pH
7.1
(6.6-b 7.6)
7.2
(6.6 -W.6)
7.4
(7.0^7.7)
7.2
(6.8-V7.4)
M-alkalinity
69.0
(34.1-v, 123.6)
62.1
(48.4-^74.1)
71.3
(60.3^93.9)
59.4
(50.9^68.7)
NH,, +-N
2.9
(0.4^ 9.8)
1.2
(0.1%4.1)
0.2
(0 -X, 1.8)
0.1
(0 % 0.7)
No2 -N
1.0
(0.2 % 2.4)
0.17
(0.06^0.3)
0.08
(0.011,0.15)
0.04
(0.01^0.14)
No ~-N
3
6.7
(2.5^ 8.7)
7.7
(5.0^9.7)
5.2
(3.1%6.2)
6.2
(4.2^7.4)
T-N
12.2
(8.1^ 19.5)
10.1
(6.2-X- 12.5)
6.4
(5.4^ 7.3)
7.2
(4.9-^8.6)
Dissolved T-N
9.7
(7.9^ 11.3)
9.9
(6.0^12.1)
6.3
(5.2^ 7.0)
7.1
(4.7^ 8.5)
OJ
o>
oo
                                          Final  sedimentation tank effluent quality  (2)
"^^^
Run-1
Mar. 30 to
Apr. 21
Run-2
Apr. 22 to
May 13
Run-3
May 14 to
Jun. 8
Run-4
Jun. 9 to
29
Org-N
1.6 '
(0.3^6.5)
1.0
(0.7-x, 1.2) ;
0.9
(0.6^1.4)
0.8
(0.6 % 0.9)
Dissolved
Org-N
0.9
(0.6^1.1)
0.8
(0.6^1.0)
0.7
(0.5-vi.l)
O.8
(0.6^0.9)
COD
1CX. 3
(9.7^11.7)
8.6
(7.8^ 9.8)
7.5
(6.0^ 8.9)
6.8
(6.1^ 8.2)
Dissolved
COD
8.6
(8.0^ 10.0)
7.3
(6.6^ 8.3)
6.7
(5.6^ 8.2)
6.3
(5.4'V 7.2)
BOD
4.6
(3.0^ 8.4)
3.5
(2.0^5.7)
2.2
(1.6^2.8) '
2.1
(0.8^4.7)
Dissolved
BOD
1.2
(0.7^1.9)
1.1
(0.7-^1.7)
l.l
(0.7%2.1)
1.3
(0.4^2.0)
SS
4.0
(2.4^5.7)
3.4
(2.2^4.0)
2.8
(I. 4% 5.0)
2.1
(l.l'v.5.5)

-------
     The alkalinity of the influent was about 130 mg/£, far higher
than originally expected, and the pH conditioning with alkali
agent was not carried out accordingly.  The T-N value of the effluent
was as high as 12.2 mg/H on the average in RUN 1, and the average
T-N removal efficiency remained at 46.3% during the period.  This may
have been caused by insufficient nitrification because the acclimation
period of the activated sludge was as short as about a week.
     From RUN 2 on, the nitrification efficiency improved.  In RUN 4,
the effluent showed little or no NHi< -N (0 to 0.7 mg/£) remaining.
     In RUN 2, the effluent T-N was 10.1 mg/£ on the average.  In
RUNs 3 and 4, it was below 8.6 mg/£, attaining a T-N removal
efficiency of 66 to 71%.  Both BOD and SS in the effluent were stabilized
below 10 mg/£.  Especially from RUN 2 on, they were almost  less  than
5 mg/£.  It is inferred that this may have been due to the  fact  that
the sludge settled fairly well with SVI of 100 to 130 and that the
surface loading of the final sedimentation tank was as low as 10 to
12 raVmVday.
     Pig. 5-2 shows an example of the composition of dissolved nitrogen
in each tank.
                                   369

-------
                                             Dissolved  N concentration  Cnig/£)
   fl>
   MI
   H,
   M
   C
   ro
   3 ^
   rt
0
3
O
PJ
^
rt
3
(t>
rt
O
O

^3
a>
h(
g"
CD
3
ft
oj
rt
H-
O
3



O
V
rt
H-
0
3




v^
3
H-
rt

1^.
H)
H-
1
%
3
I-1-
rt
J_».
HI
H-
1

0

t— *





z
o

(O






O  O
O  01
3  rt rt
•a  H- M
w  o H-
     H,
     H-
   H- O
rt
3
m
3
rt
    i
O  S  Z
O  H-  O

V  H  NJ
Q)  H-
l-<  Hi
rt  H-
3  o
n>  fti
3  rt
rt  H-
   O
   3

-------
       The mass balance of (NO2 +NO3 )-N in the RNDP is determined  in
  Fig.  5-3.
 Run 2
                    	OR	
        0.23
       23.04
23.27
    2.03
-23.24
                               1.67
                           -0.36
   63.52
+61.86
                                  Qr
    (kg/day)

Run 3
   (kg/day)
                                            Q = 5,840 i
                                            Qr » ft,080 mVday
                                            On =     0 m3/day
                Fig.  5-3  Mass balance of  (NO2 +NO3  )-N
                                     371
                                           Q = 5,920 mVday
                                           Qr = 6,100 mVday
                                           QR = 5,400 mVday

-------
The values shown are determined by multiplying the (NOa +NO3 ) -N
concentration of composite sample by the flow rate, and are given in
terms of kg/day.  The plus sign before the figures shows an increase,
and the minus sign a decrease of (NO2 +NOa )-N.   The increase corres-
ponds to that part of NHi, -N oxidized by nitrification, whereas the
decrease corresponds to the amount of nitrogen taken into the sludge
and denitrified into N2 gas.
     From Fig. 5-3, it is found that the final sedimentation tank has
a large nitrogen removal capacity;  namely, in RUN 2,  the final sedimen-
tation tank shouldered 63% of the total nitrogen removal efficiency,
and in RUN 3, 36%.  It is inferred that the denitrification in the
final sedimentation tank is mainly undertaken by endogeneous respiration.
     In RUN 2, the recirculation of the nitrified liquor was carried
out from the final sedimentation tank alone, and the recycle ratio was
about 1.  In this run, little or no denitrification took place in the
second denitrification compartment.  RUN 3 was operated by driving the
recycling pump to increase the recycle ratio to about 2 and hence to
increase the concentration of tN02  + NO3 ) -N at the inlet of the first
denitrification compartment.  In this case, the amount of nitrogen
removed in the first denitrification compartment increased, and the
amount of nitrogen removed in the final sedimentation tank decreased
equally.  Even in RUN 3, however, the denitrification in the first
denitrification compartment was predominant, and the second denitrifi-
cation compartment contributed little to the removal of nitrogen.
     By comparing RUN 2 and RUN 3, it is found that nitrified liquor
should preferably be recycled from the tail end of the nitrification
tank.  The reason is as follows.
(a)  The amount of (NOa  + NO3 ) -N running into the final sedimentation
     tank becomes small, reducing the amount of nitrogen to be removed
     in the final sedimentation tank.  As a result, the volume of scum
     generated becomes small.

(b)  It is possible to reduce the surface loading of the final
     sedimentation tank to a minimum.
(c)  As the amount of (NOa  + N°3 ) ~N running into the denitrification
     tank increases, the denitrification capacity of the denitrification
     tank can be used effectively.
                                   372

-------
    Fig.  5-4 shows the relationship between the T-N removal efficiency

(n) and the recycle ratio (R = R  + R_) .
                        J-   R
                ••v*
                                           o
                                           o
                                           CM
                                          O
                                          m
                                                (0
                                                M
                                                0)
                                                iH
                                                o
                                                (0
                                                o
                                                c
                                                0)
                                               •H
                                                o
                                               •H
                                               >M
                                               14-1
                                                0)
     o
     o
o
in
           (%) AouetDTjja
                           373

-------
     The solid line in Fig. 5-4 represents the theoretical maximum T-N
     removal efficiency (n =  ,j*  )-   The measured values are 5 to 6% higher
                              XTI\
     than the theoretical ones.  The difference may be ascribable to the
     nitrogen component taken into the sludge.
          As already stated, the demonstration plant is planned to be run
     for about one year.   In the future, the influent flow rate will be
     increased as much as possible,  and at the same time the detention time
     will be reduced.   The problems  concerning the operation and maintenance
     of the full-scale plant will be further investigated.

6.    FEASIBILITY STUDY OF NUTRIENT REMOVAL PROGRAM

          Originally,  the Lake Biwa  Regional Wastewater Treatment Plants
     were designed with the conventional activated sludge process, and the
     construction of the  Konan Chubu Purification Center was started in
     October 1978 by the  Japan Sewage Works Agency.  In October 1979, the
     Regulations Concerning Eutrophication Control in Lake Biwa were
     promulgated.  It was thus necessary to add nutrients  removal
     processes to the conventional activated sludge process.  On  the basis of
     the effluent limitations on nitrogan and phosphorus stipulated in
     the regulations,  the target effluent quality was set as shown in
     Table 6-1.
                                     374

-------
                                            Table 6-1  Target effluent quality
CO
^4
cn
Xx
BOD
COD
SS
T-N
T-P
Design influent quality
(mg/£)
180
' 70
240
30
3.3
Design effluent quality
(mg/£)
5
20
5
10
0.3
Removal efficiency
(%)
97
71
98
67
91

-------
6.1  Alternative Combined Processes

          According to the Japan Sewage Works Agency's Lake Biwa advanced
     wastewater treatment pilot plant survey results and also to the results
     of surveys conducted by the Public Works Research Institute of the
     Ministry of Construction,  four alternative plans for the removal of
     nutrient salts at the Lake Biwa Regional Wastewater Treatment Plants
     were formulated.
          Table 6-2 lists the removal efficiencies of the four alternative
     combined processes and their constituent unit processes.
                                    376

-------
                                Table 6-2  Alternative processes for nutrients  removal
CO
—I
Combined
process
I
II
Flow diagram



-

L

Aeration tank
(carbon oxidation
Nitrification +
Denitrification)


CO
Rapid sand ^
filter
(f)

Aeration tank
(Carbon oxidatior
Nitrification)


Packed bed
denitrification •
(d)

Final
+ f sedimen-
tation
tank
(c)

Activated ~j (T
carb'on | —
adsorption i
(g)

Final
i + -— sedimen-
tation
tank
(b)

(5) i Activated
— 1 carbon
j adsorption
(g)
<£
)
— ^»»
&

•i
©
i
i

Alum
precipi-
tation
(e)


Alum
precipi-
tation
(e)
^
(

j

2)
T)

Character-
istics

BOD
COD
ss
T-N
T-P
BOD
COD
SS
T-N
T-P
Removal efficiency (%)
Unit process
h


a


b

90
75
75
20
30
c
90
75
75
60
30

e
50
40
45
10
87.5
50
40
45
10
87.5
f
30
t
i
20
75
10
40

d
!
30
20
85
95
50
g
35
60
35
60
Overall
97.7
95.2
96.6
67.6
94.8
97.7
95.2
97.9
96.4
95.6

-------
                                                  Table  6-2  (Continued)
  Combined
  process
Flow diagram
                            Character
                            istics
                                                                                        Removal efficiency  (%)
           Unit process
                                                                                                               Overall
    III
oo
                 Aeration tank
                  (coagulant  addition)
o
                 Activated carbon
                 adsorption
                         (g)
                                                                       BOD
                                                                       COD
                               SS
                               T-N
                               T-P
    90


    75


    85


    20


    85
                                                                                                    30
                                                             20
                                                                   75
                                                            10
                                                                   40
                                                                     35
                                                                                                            60
                                                                                95.4
                                                                               92.0
                                                                                                  96.3
                                                                                28.0
                                                                                                 91.0
     IV
                 Aeration tank
Final
sedimentation
tank
                                (h)
                Ce)
                     (f)
                                 Activated carbon
                                1 adsorption
(g)
                                                                      BOD
                                                                      COD
                                                                       SS
                                                                      T-N
                                                                      T-P
85


70


80


20


30
                                                               50


                                                               40


                                                               45


                                                               10


                                                              87.5
                                                                                                    30
                                                                                                    20
                                                            75
                                                                                                    10
                                                            40
                                                                    35
                                                                    60
                                                                                                 96.6


                                                                                                 94.2


                                                                                                 97.3


                                                                                                 35.2


                                                                                                 94.8
                  j	I   Activated carbon adsorption process  is  planned in future

-------
          Process (I) removes nitrogen through RNDP into which a conventional
     activated sludge process is modified, removes phosphorus through the  alum
     precipitation process, and then polishes the effluent through a rapid
     sand filter.
          Process (II) uses an aeration tank for BOD removal and nitrification
     (CCONP), a alum precipitation process for phosphorus removal, and PBDP
     to denitrify and polish the effluent.
          Process (III)  removes BOD and phosphorus simultaneously by injecting
     alum into the aeration tank, and polishes the effluent through a rapid
     sand filter.  It is not provided with a denitrification process.
          Process (IV) uses a conventional activated sludge process to
     remove BOD,  a alum precipitation process to remove phosphorus, and a rapid
     sand filter to polish the effluent.  It is not provided with a
     denitrification process.

6.2  Comparison of Construction and Operation Costs

          For the four alternative combined processes, rough design calcu-
     lations were made with respect to plant capacities of 50,000 m3/day,
     100,000 m3/day and 500,000 m3/day for the purpose of comparing the
     costs for construction, operation, and maintenance.
          The conditions upon which the cost accounting was made are as
     follows.

     (1)   The wastewater treatment facility, sludge treatment facility,
          administration office and electric facility were the subjects
          of construction cost calculation.

     (2)   The sludge treatment facility was composed of thickening,
          dewatering and cake delivery, and was common to all the
          alternative processes.

     (3)   The electric charges and chemical costs constituted the operation
          costs.   The personnel costs were excluded.

     (4)   The prices as of 1979 were used for calculation.

          Table 6-3 shows the construction costs of the processes, and their
     cost functions.

                                      379

-------
                                      Table 6-3  Construction costs and their functions
to
oo
o
                                                                                        Unit:  ¥106

Process I
Process II
Process III
Process IV
Wastewater flow rate (.Q) (103 m3/day)
50
6,786
6,523
4,703
5,695
100
11,316
10,836
7,829
9,278
500
42,950
39,149
26,665
33,492
Cost function
284Q0'806
302Q° "782
244Q° '755
270Q° -?74

-------
     Table 6-4 shows the operation costs of the processes, and their
cost functions.
           Table 6-4  Operation costs and their functions
                                                           Unit:  ¥/md

Process I
Process II
Process III
Process IV
Wastewater flow rate (Q) (103 m3/day)
50
22.86
25.67
13.72
16.22
100
21.93
24.39
12.50
14.84
500
20.16
22.87
11.33
13.53
Cost function
28.2Q-0'054
30.8Q-0'048
18.4Q-0'079
21.4Q-0'075
                              381

-------
          Processes (I)  and (II)  are designed to remove not only BOD and
     SS, but also nitrogen and phosphorus.  Compared with Process (II),
     Process (I)  costs 4 to 10% more in terms of construction cost.   As
     regards the operation cost per unit volume of wastewater, Process
     (II) costs 11 to 13% more than Process (I).
          Processes (III) and (IV)  are designed mainly for removal of
     BOD, SS, and phosphorus.  It is found that Process (III) in which
     coagulant is injected into the aeration tank is 14% to 20% less in
     terms of construction cost than Process (IV) which has an indepen-
     dent precipitation process.  As regards the operation cost, Process
     (III} costs 15% to 17% less than Process  (IV).

6.3  Evaluation of Alternative Processes

          For the purpose of determining a buildup plan for the Lake Biwa
     Regional Wastewater Treatment  Plants, the four alternative processes
     were evaluated according to the following requirements.

     (1)  To meet the target effluent quality specified in Table 6-1.

     (2)  To minimize the plant modification as the construction or design
          of the plants is under way for a conventional activated sludge
          process.

     (3)  To make the best use of the already installed facilities and
          to minimize the modification costs.

     (4)  To minimize the increase in the operation and maintenance cost
          due to the addition of nitrogen and phosphorus removal processes
          to the secondary treatment facilities.

     (5)  To make the entire system flexible for future enlargement of the
          plants.

          According to these requirements, the process evaluations were made
     and Process  (1} was  finally chosen.  Table  6-5  shows  the estimated
     quality of influent  of the Konan Chubu Purification Center  and  its
     design effluent quality based  upon Process  (I).
                                    382

-------
                                      Table  6-5   Estimated  Influent and Effluent Quality
CO
oo
CO

BOD
CCO
ss
T-N
T-P
Influent
(mg/£)
180
70
240
30
3.3
Removal Efficiency (%)
Primary
Sedimentation
30 (126)
25 ( 52'5)
40 (144)
13 ( 26.1)
13 < 2'9)
RNDP
90 (12"6)
?5 (13.1)
75 (36'0)
60 (1°'4)
30 ( 2'0)
Alum
Precipitation
50 ( 6'3)
40 ( 7'9)
45 d9-8)
10 < 9'4)
85 ( °'3)
Rapid sand
Filter
30 (4'4)
20 (6'3)
75 (5'0)
-
40 (°'2)
Effluent
(mg/Jl)
4.4
6.3
5.0
9.4
0.2
                    Remark:  Figures  in parenthesis  show  effluent quality of each unit process.

-------
           Two wastewater treatment plants of Lake Biwa Regional Sewerage
      System are now under construction adopting Process  (1).  In 1982, the
      Konan Chubu Purification Center will start service.  This marks the
      first practical step in the implementation of the nutrients removal
      process in Japan.  And every effort will be made to ensure the success
      of the eutrophication control project in Lake Biwa.
REFERENCES

(1)   Downing, A.L., et al., "Determination of Kinetic Constants for
     Nitrifying Bacteria in Mixed Culture with the Aid of an Electronic
     Computer," J. Gen.  Microbiology, 38 (1965)

(2)   Kazuhiro Tanaka, "Kinetic Studies on Recycled System for Biological
     Nitrification and Denitrification," Progress Report, US/Japan Joint
     Research Project (Japanese Side), March 1981.
                                   384

-------
                                      Eighth US/JAPAN Conference
                                              on

                                      Sewage Treatment Technology
  EFFECT OF DETERGENTS AND SOAP
                        ON
MUNICIPAL WASTEWATER TREATMENT
                   October 13-14, 1981

                   Cincinnati, Ohio USA
    The work described in this paper was not funded by the
    U.S. Environmental Protection Agency.  The contents do
    not necessarily reflect the views of the Agency and no
    official endorsement should be inferred.
            K. Kobori, H. Watanabe and K. Murakami

            Water Quality Control Division,

            Public Works Research Institute,

            Ministry of Construction



                         385

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1.    INTRODUCTION

          In the field of sewage  treatment,  it was  in  the  1960's that  in-
     creasing concern was first paid  to  synthetic detergents.  This was
     because ABS, that was considered to be  biologically hard, brought about
     a foaming reaction in aeration tanks or some other apparatus.  In Japan,
     softening of synthetic detergents was started  in  1965 and completed in
     1973.   Afterwards,  there  is  almost  no problem  of  the  surfactants  contained
     in synthetic detergents in sewage treatment.
          Lately, however, a number of people have  again been  concerned with
     synthetic detergents.  The two events described below have led to this
     concern.

     1)   For the purpose of water pollution  control in Lake Biwa, Shiga
         prefectural authorities  established a regulation  against the  sale
         and use of synthetic  detergents containing phosphate.  It is  called
         the "Regulation on the Prevention of Eutrophication in Lake Biwa"  and
         was put into force in July,  1980.

     2)   Mishima city authorities distributed synthetic detergent and  washing
         powder to each home in a certain housing area in  order to compare
         their influence upon  the sewage treatment  process. As a result, it
         was found that organic loads and PO4 load  of  influent were reduced
         and the water quality of effluent was markedly improved by replacing
         synthetic detergent with powdered soap.
              With the above two  events  as a turning-point, a  considerable
         number of local public authorities  have  investigated  the influence of
         phosphate-containing  synthetic  detergents, phosphate-free synthetic
         detergents and powered soap  upon the environment  and  the sewage
         treatment.
              Fig. 1 shows the products  of synthetic detergents  and  soaps  in
         Japan.  The amount of soaps  usped over  the period from  1976  to  1980
         was 1.36 ^ 1.73 kg/head/year (average  1.48 kg/head/year), and the
         amount of synthetic detergents  used was  6.88  ^  9.14 kg/head/year
         (average 7.75 kg/head/year). The total  amount of detergents  used
         was 8.24 ^ 10.70 kg/head/year  (average  9.23 kg/head/year).  The term
         "detergents" used here is intended  to  include synthetic detergents
         and soaps.
                                      386

-------
     Almost all the surfactants as detergent materials are made from
petrochemicals except for the fatty acid salts and certain types of
higher alcohol.  Major surfactants used in Japan include linear alkyl
benzene sulfonate  (LAS), alkyl sulfate  (AS), polyoxyethylene alkyl
ether sulfate  (AES), alpha-olefin sulfonate (AOS), fatty acid salt
(FA), and polyoxyethylene alkyl ether (AE).  AE is a nonionic
surfactant and the others are all anionic surfactants.
     The present report evaluates the influence of  detergents on the
sewerage system, based on the indoor experiments and on the firld
investigation conducted at sewage treatment plants.  The purpose of
this investigation was to clarify the following:

1)  Discharge of surfactants from houses to a sewage treatment plant
2)  Concentration of surfactants in sewage
3)  Behavior of surfactants in sewage treatment process
4)  Influence of detergents on activated sludge process
                                  387

-------
                                       Synthetic
                                       detergents
           Washing soap
             (powdered'
Washing soa
  (Solid)
                      i:i:X*X:X;Xy.X Bathing soap
1960
1965
                              1970
                              1975
                                                          1980
Fig. 1  Products of synthetic detergents and soaps in Japan
                          388

-------
2.   ANALYSIS OF SURFACTANTS

 2.1  ANIONIC SURFACTANTS (EXCLUDING FATTY ACID SALTS)

           The concentration of anionic surfactants  in  the  water sample  was
      determined by the colorimetric method of methylene  blue  active  sub-
      stances (MBAS).
           The concentration of anionic surfactants  in  sludge  was determined
      by measuring  MBAS in the  extract  which had been obtained through the
      reflux of sludge  with ethyl  alcohol.

 2.2  NONIONIC SURFACTANTS

           The concentration of nonionic surfactants in the water sample was
      determined by the colorimetric method of cobalt thiocyanate active
      substances (CTAS).
           The concentration of nonionic surfactants in
      sludge was determined by  measuring CTAS in the extract which had been
      obtained through  the reflux  of sludge with ethyl  alcohol.   However,
      CTAS  was only derived from the surfactant, but also detected from
      activated sludge.   The concentration of CTAS from activated sludge was
      about 20 mg.CTAS.2000 mg.MLSS.

 2.3  FATTY ACID SALTS

           The fatty acid salts in the  water sample were  extracted with
      chloroform and acethylated with the addition of N,N-dimethylformamide
      dimethylacetal, and determined by gas chromatgraphy (FID).
           Fig.  2 shows one example  of  the  gas chromatograms prepared for the
      measurement of the  fatty  acid  salts.
           The fatty acid salts in sludge were extracted  with  chloroform by
      use of soxhlet extraction and  the extract was operated in the same
      manner as  the water sample.
           The fatty acid salts measured were palmitate,  oleate and stearate.
      However,  oleate was calculated in terms of stearate and  the sum of,
      palmitate  and stearate was regarded as the value  of fatty acid  salt.
                                     389

-------
                           Methyl palmitate
                                    Column
                                      Silicone OV-17/
                                      Chromosorb W (AW-DMCS)
                                      2%, 6OX/80 mesh
                                      3 mm0 x 1 m
                   Methly
                   Myristate
Column temp.
Carrier gas
  N2, 20
                                                    180°C
                                         Methly Oleate
                                              \Methly
                                                  Stearate'
Fig. 2  Gaschromatogram of fatty acid methyl esters
                              390

-------
3.
LOSS OF SURFACTANTS IN SEWER SYSTEM
 3.1  EXPERIMENT ON SOLIDIFICATION OF DETERGENTS

  3.1.1  Method

              This experiment was  conducted as  follows.   Sample  solutions of
         sewage were filtered with filter paper No.  5C and  detergents were
         added.  Then,  the  solutions  were stirred  for 1  hr  with  stirrers and  SS,
         TS,  VTS,  COD,  and  TP in the  suspensions were measured.  Further, the
         suspensions were filtered with GF/B, and  COD and TP  in  the  filtrates
         were measured.  The  types of detergents used in this experiment are
         shown in Table  1.  The amounts of  detergents added were 500, 1000,
         2000 and 3000 mg/1 respectively.

                  Table  1   Detergents and their major components
Detergents
I
II
III
IV
Powdered washing soap
Synthetic detergent
Phosphate free
synthetic detergent
Phosphate free
synthetic detergent
Major components
Surfactant (70%)
Surfactants (24%) , Phosphate (10%)
Sulfate (10%<) , Silicate (10%<)
Surfactants (20%), Sulfate (10%<) ,
Silicate (10%<) , Almino Silicate (<10%)
Surfactants (24%) , Carbonate (10%<) ,
Sulfate (10%<) , Silicate (10%<) ,
Almino Silicate (<10%)
             The standard amount of detergents used  for washing  at  home  is
        40 g/30 I.
                                     391

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3.1.2  Results and discussion

            The solidification rate of detergents  was  calculated in terms  of
       (SS/TS)  x 100.   As a result, the rates of detergents  I,  II,  III  and
       IV were 15.8 ^  51.2% (average 30.4%),  4.6 ^ 8.1% (average 6.2%),
       10.5 ^ 13.1% (average 12.0%) and 8.3 ^ 9.8% (average  8.9%)  respect-
       ively.  For detergent I, there was a tendency for the solidification
       rate to decrease as its concentration  was increased.   For the other
       detergents, the solidification rate was almost  constant regardless  of
       their concentration.
            Assuming that the solidification  rate  of organic components in
       detergents can  be expressed as the solidification rate of CODMn, that
       of organic components was calculated in terms of (1 - D-COD/COD) xlOO.
       As a result, the rates of detergents I, II, III and IV were 36.2 ^
       73.3% (average  56.6%), 2.2 ^ 12.6% (average 7.3%),  0  ^ 12.6% (average
       3.2%) and 0^5% (average 1.8%) respectively.  The organic matter
       contents of the above detergents were  calculated in terms of (VS/TS)
       x 100,  and they were 62.4%, 30.9%, 19.2% and 20.7% respectively.
       The product of the organic matter content in a detergent with its
       solidification rate of organic components represents  the solidifica-
       tion rate of organic components for the detergent.   The values in
       detergents I, II, III and IV were 35.3%, 2.3%,  0.6% and 0.3% respect-
       ively.  Comparing these values with the solidification rate of
       detergents, the following can be considered.

       1)  For washing powder, 30 ^ 35% of the powder added to water is
           solidified, solidification rate of soap is higher than that of
           synthetic detergents.  The solid matter is almost completely
           composed of organic substances.  Therefore, it seems that the
           high solidification rate of powdered soap is due to the  formation
           of metallic soap as a result of the reaction with Mg++ and Ca++
           ions in the sewage.
                                    392

-------
       2)  The solidification rate of phosphate-containing synthetic
           detergents is about 6%, rather low in comparison with that of
           powdered soap and phosphate-free synthetic detergents.   About 1/3
           of the solid matter is composed of organic matter and the remain-
           der is inorganic.  It is confirmed that phosphate,  one  of the
           major inorganic components, completely dissolves in water.
           Further, it is hardly considered that sulfate becomes solidified.
           Accordingly, most of the solidified inorganic matter is presumed
           to be silicate.

       3)  The solidification rate of phosphate-free synthetic detergents
           is 9 ^ 12%, rather higher than that of phosphate-containing
           synthetic detergents.   Inorganic matter occupies 95 'x- 97% of
           the solid matter.  The solidified inorganic matter  is presumed
           to be composed mainly of silicate and almino slicicate.

3.2  SEDIMENTATION OF SURFACTANTS IN HOUSE INLET AND THEIR ADHESION TO
     SEWERS

 3.2.1  Method of investigation

             It has been said that when synthetic detergents for washing are
        replaced by powder soap,  the load of organic pollutants, especially
        BOD load,  reaching the sewage  treatment plant will increase.
        In order to estimate such increase of pollutants,  it must  be taken
        into consideration that powdered soap precipitates in  house inlets  or
        adheres to the sewers.  As a result,  the rate of the pollutants
        reaching the treatment plant becomes constant,  which means that
        equilibrium is established in the sedimentation,  adhesion, desquama-
        tion,  and biodegradation of powdered soap.
             This investigation was conducted at the F sewage  treatment
        plant in F City in March  1981.   The F sewage treatment plant and its
        covering area are summarized below:

             Inhabitants                              5700
             Inflow                                   1200 m3/day
             Aeration time                            13.7 hrs
             Return sludge rate                       100%
                                     393

-------
     Surface loading of primary
     sedimentation tank                        6 m^/m^/day
     Surface loading of final
     sedimentation tank                        5.3 m-^/m^/day

     The F sewage treatment plant is located in a sloping area
of the city, so that time sewage takes to reach the plant is about
20 min.
Fig. 3 is a flow diagram of the F sewage treatment plant.
     In order to investigate the influence upon the sewage treatment
when syenthetic detergents for washing has been replaced by powdered
soap, the F City authorities distributed washing powder free of
charge to each household in this area over a four-month period from
September to December 1980.
     The results of the investigation during this period have not yet
been compiled.  In the households of this area, 78.6% of the total
had been using synthetic detergents until September 1980, but during
the period from September to December 1980, 98.9% of the total house-
holds used washing powder instead of synthetic detergents.  In January
1981, a questionnaire survey was conducted concerning the use of
powdered soap in each home of this area.  According to the results
of the survey, 70% of the total households answered that they would
continue to use powdered soap.  Accordingly, it is presumed that a
considerable number of the households were using powdered soap during
the period of this investigation, which was conducted in March 1981.
     The investigation on the sedimentation of soap in house inlets
was conducted at the house inlet for five households in a 5-story
public apartment house in this area.  First, all the sediment
deposited in the house inlet was collected, and  CODM ,  TS, TP, KN,
MBAS, CTAS, and fatty acid salts in the sediment were measured.
Two days later, the sediment was again collected from the same house
inlet, and the same items were measured.  The investigation on the
adhesion of soap to the sewer was conducted at two manholes in this
area, collecting the adhesive from the bottom or thereabout of the
Hume concrete pipe.  Then, CODM  , TS, TP, KN, MBAS, CTAS, and fatty
acid salts in the adhesive were measured.  Two days later, the
adhesive was again collected from the same pipes, and measurements
were made for the same items.
                                  394

-------
                                                 Fixed flow tank
CO
VO
Ol
^Influent from KODAN
"^^1,150 m3/day
Cr} 	 ^ ^>primarY1. J 	 ^
\yj A ^ seaimenta-j
j if tion tank!
-1 !i LT
from TEIDAN 1 1 I
jl 420 m3/day
!" -r-
l| !V-t]
!! 'l *
Supernatant | |
1 1 liquor | j
ll 50 m3/day ||
M< i
i H
1 '
1 ll
1 II
It ^
T^v 1
1 I ., . ... 1 ' 7
Ml £ 	 1 	 'Sr-
	 1 1 V Aeration *" :'
Regulating tank ™





^^^Vi^J °6C


dudge 1 1
mceflt- j i
ition J (>
H^an^/ f^l
I i
Dehy- 1
drator m"^ Sludge cake
"~~n ^ i
if Supernatant liquor 10 m^/day 1
^ Washing water 360 m3/day j
Secondary effluent 1200 m3/day
inal sedi-J " "
entation 1 1 1
anS-*-- 	 ||
/ II
II
_, ii
)der f 	 J|

^ Flow of sewage
^••••1 Flow of sludge

-------
       The term "adhesive"  used herein  indicates  the  solid matter  adhering
       to the metal brush with  which a  fixed  area of  the Hume pipe was
       brushed.

3.2.2  Results and discussion

            Table 2 shows the  results of measurement  for  the sediments  in a
       house inlet and the  adhesive to  Hume concrete  pipes.
            The drainage, not  containing feces,  from  5 households  ran into
       the house inlet, of  which the size was 45 cm x 45  cm  x 60 cm  deep.
       Assuming that the average number of families for each household  is
       3.5, the total number of persons for the  house inlet  is  17.5.
       Assuming that all the house inlets in this area have  the function
       equal to the investigated inlet, the sediment  per  day in this area
       is estimated as follows:
       Example:  Fatty acid salts
                      Sediment for two days
                      Sediment per head per day

                      Total sediment in this area
22.4 g/5 families/2 days
(22.4 * 17.5)  f 2 =
0.64 g/head/day
0.64 x 5700
                                                      1,000
            = 3.65 kg/day
            The value of 3.65 kg/day is considered to be maximum value per
       day in this area (maximum sediment).   The results of calculation on
       the maximum sediment in the house inlet are shown in Table 2.
            The estimation of the adhesive in the Hume concrete pipes is
       also shown in Table 2.  The estimation of maximum adhesive was
       conducted as follows:
       Example:  Fatty acid salts
                      Adhesive for two days
                      Total length of sewer pipe
                      Pipe diameter
                      Total area of pipe wall
                      Total adhesion in this area
                                     396
0.1 g/nr/2 days
14,140 m
jz(250 ^ 400 mm, assuming
that the average is
0300 mm.
13,300 m3
0.1 x 13300
 2 x 1000
            = 0.66 kg/day

-------
     The value of 0.66 kg/day is considered to be maximum value per
day in this area (Maximum adhesive).
     The actual adhesive on the Hume pipes is presumed to be a far
smaller value than the maximum adhesive (Table 2).  Because the
adhesive on the Hume pipe does not adhere to the whole wall inside
the pipe in a uniform manner and much more adhesive is considered to
be on the portion closer to the bottom of the Hume pipe, while the
adhesive in the pipe was estimated by the values of the portion
close to the bottom.  Further, the maximum adhesive obtained is the
value for a new wall of the Hume pipe.
     Table 3 shows the maximum sedimentation in the house inlet, the
maximum adhesive in the Hume pipe and the discharge from house to
sewage treatment plant.  Taking into consideration that the maximum
adhesive on Hume pipe has been overestimated, the discharge of TP,
KN, MBAS and CTAS is presumed to be more than 95%.  However, even
considering that the maximum adhesive on Hume pipes has been over-
estimated, the discharge of fatty acid salts is considered to be
about 70%.
          Table 2  Measurement of sediments in house inlet
                   and adhesive in Hume concrete pipe
^\



House
inlet




Hume
pipe

, ^\:
Equilibrium
sediments
(g/5 families)
Sediments for
two days
(g/5 families/
two days)
Equilibrium
adhesive
(g/ir.2)
Adhesive for
two days
(g/m2/two days)

COD»
Mn

41.5


-



12.8

3.06

TS

1250


280



55.3

11.9

VTS

467


187



30.3

6.4

TP

5.43


1.32



1.09

0.33

KN

33.4


5.98



3.6

0.55

MBAS

1.44,


0.73



0.85

0.058

CTAS

2.19


2.06



0.16

0.026
Fatty
acid
salts

72.5


22.4



0.35

0.10
                            397

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Table 3  LOSS of TP, KN and surfactants in sewer*system
^\__^
^~~^---^_^^
^--~^___

I



II


III




Maximum sediment
in house inlet
(kg/day)
Maximum adhesive
in Hume concrete

pipe
(kg/day)
Influent loadings*
(kg/day)
Discharge from
house to sewage
treatment plant
(III/(I-fII+III)
x 100)

TP


0.2


2.2



11.1


82.2


KN


1.0


3.6



67.8


93.6


MBAS


0.12


0.38



5.51


91.7


CTAS


0.34


0.18



7.24


93.3

Fatty
acid
salts

3.65


0.66



9.26


68.2

       *  Refer to Table 5, inhabitants 5700
                             398

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4.   BEHAVIOR OF SURFACTANTS IN SEWAGE TREATMENT PLANT

 4.1  SURFACTANT CONCENTRATION IN SEWAGE AND SLUDGE

           There are several reports on MBAS concentration in the influent.
               2)
           Sudo   conducted investigation at a municipal sewage treatment
      plant in 1979, and reported that MBAS in influent was 5.9 ^ 7.9 mg/£
      and the removal by the secondary treatment was 93 ^ 96%.  Yamane et
      al.3) report that MBAS in influent was 11.7 mg/£ (weekly mean)  at a
      housing area sewage treatment facilities for the inhabitants of 1000
      %  1400.
           In this investigation, in order to clarify the surfactants in
      sewage and sludge, MBAS, DTAS and fatty acid salts were fractionally
      determined.

  4.1.1  Method of investigation

              Investigation was conducted 7 times at 5 plants.  For influent,
         primary effluent and secondary effluent, sampling was conducted at
         1 or 2 hour intervals and a 24 hr composite sample was prepared
         by mixing in proportion to the flow for each day.  The primary sludge
         and waste activated sludge were sampled once a day.
              MBAS, CTAS and fatty acid salts in each sample were analyzed.

  4.1.2  Results and discussion

              The results of analysis for each type of surfactant is shown in
         Fig. 4.  MBAS in the influent was 2.5 ^ 6.4 mg/X,  (average 4.7 mg/&) ,
         CTAS 1.9 % 4.8 mg/H  (average 3.1 mg/£) , and fatty acid salts 2.4 'v
         6.7 mg/& (average 4.1 mg/&).  MBAS in the primary effluent was 2.5 ^
         15.0 mg/£ (average 5.9 mg/£), CTAS was 1.8 ^ 23.0 mg/£  (average 7.9)
         and fatty acid salts was 0.6 ^ 2.3 mg/£ (average 1.6 mg/&).
         MBAS and CTAS in the primary effluent were high in comparison with
         those in the influent.  It was because the values at one plant were
         abnormally high.  If these abnormal values are excluded, MBAS and
         CTAS were 3.6 mg/i and 4.1 mg/£, respectively, on the average.
         MBAS in the secondary effluent was 0.3 ^ 0.7 mg/£  (average 0.5 mg/fc),
         CTAS was 0.1 ^ 1.1 mg/H (average 0.6 mg/£) and fatty acid salts were
         0.4 ^ 4.3 mg/fc (average 1.6 mg/£).
                                       399

-------
14 r
The concentration of Surfactans (mg/£)
M H
O tO £> & 03 O M
-
^
Fatty
acid
salts
CTAS
MBAS


Fatty
acid
salts
CTAS
MBAS

Fatty
acid
salts
CTAS
MBAS
Influent Primary Secondar
effluent effluent
  Fig.  4  Surfactants  in sewage
                400

-------
     As a result, MBAS removal was 23% in primary sedimentation.
CTAS concentration was 32% higher in the primary effluent than in the
influent.  The cause is not apparent, but the influence of back
water from the sludge treatment system can be considered.  Because
CTAS not derived from detergents was detected in activated sludge.
The removal of fatty acid salts was 61% in primary sedimentation.
     The removal by secondary treatment were 86% for MBAS, 85% for
CTAS and 0% for fatty acid salts.
     Therefore, it was found that MBAS and CTAS were removed mainly
in the activated sludge treatment process and fatty acid salt was
removed mainly in the primary sedimentation tank.
         120

       ~ 100
(d
-P
o
id
       o
       •<-{
       -P
       0)
       o
       c
       o
          80
           60
           40
           20
Fatty
acid
Salts
                    CTAS
                    MBAS
                            Fatty
                            acid
                            Salts
                                   CTAS
                                   MBAS
               Primary sludge   Return sludge
             Fig.  5  Surfactants in sludge
                                 401

-------
             The results of analysis for several types of surfactants con-
        tained in primary sludge and return sludge is shown in Fig. 5.
        In primary sludge, MBAS was average 3.8 mg/g, CTAS was average
        3.0 mg/g and fatty acid salts were 96.9 mg/g.  The concentration of
        fatty acid salts in primary sludge was high,  which coincides with
        the tendency of fatty acid salts to be removed in primary sedimen-
        tation.
             In return sludge, MBAS was 3.4 mg/g,  CTAS was 19.7 mg/g and
        fatty acid salts were 47.2 mg/g.
             As a result of analyzing the activated sludge that was cultivated
        with detergent-free synthetic sewage,  MBAS was 1^2 mg/g, CTAS was
        10 ^> 11 mg/g and fatty acid salts were about 5 mg/g.  These results
        suggest that the high CTAS value found in return sludge was not due
        to the detergent itself and certain components in activated sludge
        were detected as CTAS.
             As for fatty acid salts found in return sludge, the influence
        of food oil and others can be considered as one of the causes for
        its high concentration.

4.2  BEHAVIOR OF SURFACTANTS IN SEWAGE TREATMENT PROCESS

 4.2.1  Method of investigation

             Investigation was conducted at F sewage treatment plant in F
        City.  Treatment facilities and operational conditions have already
        been outlined in 3.2.1.
             As shown in Fig. 3, the influent to F treatment plant was
        composed of "influent from KODAN" coming from the major part of a
        housing area and "influent from TEIDAN" consisting of 50 m^/day of
        domestic sewage and 420 m-^/day of back water.  For the influent from
        TEIDAN, as the fluctuation of pollutants load was considered to be
        low in the course of a day, sampling was conducted 4 times a day, but
        for the influent from KODAN, as a rule, sampling was conducted
        every hour.
                                      402

-------
            For the influent to the aeration tank and secondary effluent,
       samples were collected every hour, and 2-hour composite samples were
       prepared.
            The measured items are as shown in Table 4.

                      Table 4  Measured items
       Influent  Flow  (overall width weir method)

       Effluent   Flow (flowmeter)
                                      COD     D-TOC  NBAS      pH
       Water temperature               D*-COD  K-N     D*-MBAS  BOD
       Fatty acid salts                SS      D-K-N   CTAS     SS
       D*-Fatty acid salts             TS      T-P     D*-CTAS

                                       VTS     D*-T-P
       Note:  * indicates the filtrate filtered with GF/B.

4.2.2  Results and discussion

            The results of investigation are summarized in Table 5.   For the
       average concentration of influent, BOD was 201 mg/£, COD 91.4 mg/&,
       SS 219 mg/£, KN 44 mg/£ and TP 7.2 mg/£.  These are average values
       for small-scale treatment plants for housing areas in Japan.   In the
       plant, as the regulating reservoir was installed, the water quality
       was uniformalized to a certain degree so that the minimum concentra-
       tion of influent to the aeration tank was higher than that of the
       influent to the plant.
            Concerning these general water quality items, their removal by
       treatment was favorably conducted and the operation of the plant was
       excellent during the investigation.
            MBAS in influent was 3.6 mg/£, CTAS 4.7 mg/£, and fatty acid
       salts 6.0 mg/£.  MBAS concentration was low in comparison with
       11.7
                                     403

-------
The proportions of suspended type of these components in influent was
almost 0% for MBAS, 20% for CTAS and 56% for fatty acid salts.
MBAS is almost soluble, but its removal before the aeration process
was nearly 30%.  In this plant, the retention time in the primary
sedimentation tank was 9.3 hrs and, if the retention time in the
regulating reservoir is added to the above time, the average retention
time becomes 13.7 hrs.  A considerable biodegration must be conducted
through these processes.  The removal of fatty acid salts was 77%
before the aeration process.  Therefore, it can be considered that
biodegration took part in the removal of the above fatty acid salts.
     In the aeration tank and final sedimentation tank, MBAS removal
was 86% and CTAS was 91%.  The concentration of fatty acid salts in
influent of the aeration tank was comparatively low.  Its removal
was only 67% by activated studge process, but the total removal
through the whole process reached 92%.
     The total removal of MBAS and CTAS were 90% and 92% respectively,
and the removal rates were also considerably high.
                                 404

-------
Table 5  Measurement of water quality
Type
Influent
Influent
to
aeration
tank
Secondary
effluent
Classifi-
cation
Average
Maximum
Minimum
Average
Maximum
Minimum
Removal
by
primary
sedimen-
tation
Average
Maximum
Minimum
Removal
by
aeration
Total removal
Flow
(m3/hr)
64
197
27
-
-
-
-
-
-
I

; —
Tempe-
rature
(°C)
-
16.9
13.1
-
14.6
13.8
-
-
13.9
12.9
-
-
BOD
P" 
-------
     Table 6 shows "per capita loading daily" calculated from total
influent loadings (g/day) and inhabitants.  In the table, the
number indicated in parentheses is the reference value for the basic
unit based on the "Sewerage Facilities Design Manual and its
Commentary" published by the Japan Sewage Works Agency.
     The organic pollutants as BOD and COD in the table are not
as high as the values in the "Design Manual".  Even in the area where
powdered soap as used at a high rate, a marked increase in "per
capita loading daily" is not found.  On the contrary, even if
synthetic detergents were not used so much, there was no tendency
for the TP value to decrease.
              Table 6  Per capita  loading daily
                                             (Unit:  g/capita/day)

BOD 5

54.3
(44^4)

CODMn

24.5
(22^A2)

SS

59.2
(400,70)

T-P

1.95
(1.4^2.2)

K-N

11.9
(12^13)

MBAS

0.97

CTAS

1.27
Fatty
acid
salts
1.6
                                406

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5.   INFLUENCE OF DETERGENTS ON ACTIVATED SLUDGE PROCESS

 5.1  EFFECT OF DO IN AERATION TANK

           DO level in the aeration tank is the important factor affecting
      the activated sludge treatment.   The purpose of this experiment was to
      investigate the influence of surfactants upon the activated sludge
      treatment when the DO concentration in the aeration tank was lowered.

  5.1.1  Method of investigation

              In this experiment,  activated sludge was placed in a container
         and stirred to prevent the sludge from precipitating.  The control
         of DO was conducted by the adjustment of aeration.   The cultivation
         was conducted by the till and draw method once a day.  The DO level
         was controlled through conversion of the air rate through two-step
         adjustment.
              The air rate for high DO level was set at about 600 mJl/min
         so that,  after the addition of substrate, the DO saturation could
         be reached in 1 ^ 3 hours. The air rate for low DO level was set
         at about 300 mH/min so that the DO saturation rate  could reach 10 ^
         30% in 24 hours.  In case of  low DO,  its control was difficult in
         this experiment.  Dodecylbenzenesulfonic acid sodium salt (DBS)  was
         added,  at concentrations  of 5 mg/H,  10 mg/£ and 20  mg/£, to the
         synthetic wastewater having BOD of about 150 mg/Jl.   If the concent-
         rations of DBS are converted  to MBAS concentrations, they are
         7.2 mg/£,  14.5 mg/£ and 29.0  mg/£  respectively.

  5.1.2  Results and discussion

              The water quality of effluents is shown in Table 7, and DBS
         decay in the aeration tank is shown in Fig.  6.   Table 7 shows the
         values obtained after 24  hours of reaction time had elapsed.
         Under the conditions of low DO, when the concentration of DBS was
         higher, DBS in the effluent tended to increase.  In case 29 mg/£
                                      (
         as MBAS was  added,  DBS remained by 27% in the effluent.
                                     407

-------
     When the low DO conditions were compared with the high DO
conditions, the addition of 7.2 mg/£ as MBAS did not bring about the
influence of DO, but on adding 14.5 mg/£ as MBAS, a change in
effluent quality concerning TOC and BOD was found.  There was almost
no change in COD and MBAS.
     In the change with time during 24 hours, as shown in Fig. 6,
the removal of TOC under the addition of 14.5 mg/H as MBAS was pro-
gressing favorably in low DO condition for 5 hours, but the high DO
condition  was preferable for 24 hours.  In case 29 mg/£ as MBAS
was added, the similar change of TOC with time appeared for 5 hours,
but the values obtained after 24 hours were better in high DO.
condition.
                                 408

-------
                                       Table 7  Water quality  of effluents
^^-v^Analysis
Sample ^s\_
Low
DO
concent-
ration
High
DO
concent-
ration
DBS
7.2
(mg/A)
DBS
14.5
(mg/A)
DBS
29.0
(mg/A)
DBS
7-. 2
(mg/A)
DBS
14.5
(mg/A)
DBS
29.0 '.
(mg/A)
BOD (mg/A)
Measured
5.1
4.0
4.6
9.5
14.4
11.1
6.4
31.0
12.3
5.7
5.6
7.1
8.4
1.9
4.7
4.9
4.0
5.0
Average
4.6
11.7
16.7
6.1
5.7
4.6

COD (mg/A)
Measured
6.6
5.5
8.4
9.7
8.1
15.5
11.9
18.5
27.4
13.1
8.1
8.2
13.5
10.0
11.4
11.3
7.5
11.0
Average
6.8
11.1
19.3
9.8
11.6
9.9

TOC (mg/A)
Measured
8.6
9.6
4.7
11.3
22.1
19.3
18.0
43.3
36.1
4.5
3.1
11.4
4.6
9.6
10.3
9.7
14.3
9.5
Average
7.6
17.7
32.6
8.9
8.3
11.2
MBAS (mg/A)
Measured
0.34
0.29
0.43
0.34
6.23
9.27
0.30
0.41
0.79
0.49
1.55
1.23
Average
0.32
0.39
7.75
0.34
0.64
1.39
Dissolved
COD
(mg/A)
6.1
6.7
16.6
5.5
6.7
7.3
Dissolved
TOC
(mg/A)
1.7
10.5
23". 9
6.7
4.1
3.2
-p.
o

-------
5.1.3  Summary
            When DBS concentration was  14.5 mq/H or less as MBAS,  there was
       no influence on the water quality of the effluent.   But when 29 mg/SL
       of MBAS was added,  MBAS was liable to remain in effluent under the
       conditions of low DO.   The operational condition was stable when the
       DO concentration was high.  In MBAS concentration flow into the plant,
       at present, no influence of DO level was found.
                                     410

-------
High DO condition
                                                                 Low DO condition
g  10
>   8

f   6
S.   4
J"=>
~   2
    0
DBS 7.2
O
            [o MBAS in mixed liqour
               MBAS in supernatant liquor
            la TOC
            Lo DO            A    J100
                                   80
                                   60 '
                                   20
                                   0
                                                            DBS 7.2 mg/Jl as MBAS
L     2     3     4
        Time (hours)
 High DO condition, DBS 14.5 mg/£ as MBAS
                                       130
                                  100
                                        20
                                                                  345
                                                                 Time (hours)
                                                                                          24
                                                 100
                                                 80
                                                 60 D
                                                   O

                                                 20
                                                 0  "
                                                                                              20
                                                                                              10
                                                       Low DO condition, DBS  14.5 mg/£  as  MBAS
                                 . 80
                                                                                             , 30
                            24
                                          0
        Time (hours)
 High DO condition, DBS 29 mg/£ as MBAS
                                 -i 100 ., 50
           3     T
        Time  (hours)
40 R
30 =r
20 ^
10
 0
                                                30
                                               220
                                                 0
                                                                        Time  (hours)
                                                               Low DO condition, DBS  29  mg/£ as MBAS
                                                                                                100  -50
                                                                                                     40
                                                                                              - 80   -
                                                                                              •60g-
                             Fig. 6  DBS decay  in aeration tank
                                                                        345
                                                                        Time  (hours)
                                                                                  24
                                                                                             30
                                                                                             20
                                                                                             10
                                                                                              0
                                                                                                   I
                                                                                                  I
                                                                                              10   -
                                                                                                   O
                                                                                                   O

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5.2  EXPERIMENT FOR TREATMENT OF  DETERGENTS ADDED  TO  SYNTHETIC  SEWAGE

          In order to clarify the influence of  detergents  on  activated  sludge
     treatment, this experiment was  conducted under the  conditions of the
     conventional activated sludge method.  The influence  of  detergents was
     investigated by examining the water  quality of the  effluent, and the
     properties of sludge,  biota  and some other factors.

 5.2.1  Method

             The detergents used  were powdered  soap,  nonionic synthetic
        detergents, anionic synthetic detergents,  and Zeolite containing
        detergents.  These  detergents (Table  8) are all  commercially
        available.
             The main components  of  synthetic sewage  are meat extract,  yeast
        extract, peptone and some minerals.   Seed  sludge is the sludge  in  a
        sewage treatment plant which is operated under a comparatively  low
        organic loadings.
             The experimental apparatus is  composed of a 100-&  aeration tank
        and a 50-& sedimentation  tank. The aeration  tank  is divided into
        ten sections with partitions.
             The experiment was conducted in a  constant-temperature room at
        20°C with an aeration time of about 7 hrs  for about 70  consecutive
        days.
             The amount of detergents added is  shown  in  Table 8.  This
        concentration is somewhat higher  than that of detergents detected in
        the influent of the sewage treatment plant..
             However, the amount  of Zeolite-containing detergents was reduced,
        because its foaming reaction was  remarkable in the aeration tank.
                                      412

-------
         Table 8  Detergents added to synthetic sewage
Unit
A
B
C
D
E
Detergents
Control
Powderd washing soap
Nanionic synthetic detergent
Anionic synthetic detergent
Zeolite containing detergent
Dose (mg/2,)

80 (48)*
60(14.4)
60(14.4)
40 (8)
         Note:   *  The number of (  )  means  the  concentration  of  surfactants

5.2.2  Results  and discussion

            The results of the experiment are shown in the  table in terms
       of the average values during the period  that was considered to be
       a steady state.  These values were obtained about 1.5  months after
       the experiment had been started.
            The water quality of the influent and the properties of sludge
       are shown in Table 9, and the water  quality of the effluent and
       removal  are shown in Table 10.  When detergents were added to the
       synthetic sewage, powdered soap and  Zeolite-containing detergents
       produced turbidity, and the  formation of SS was observed.
            Although the DO concentration in the aeration tank was compara-
       tively high during the experimental  period, it can be  thought that
       the operation was completed  under the conditions of  the conventional
       activated sludge method.
            In  the case of powdered soap, SVI was high, and the  most sludge
       was produced.  The conversion rate of BOD to sludge  was about 0.6  for
       powdered soap, and 0.3 ^ 0.4 for other detergents.
            As  shown in Table 10,  the water quality of effluent  processed
       by each  apparatus showed a favorable value; the removal of organic
       matter was high; and no adverse influence due to the detergents was
       found.  Further, nitrification took  place.
                                    413

-------
The removal of Nitrogen and Phosphorus was rather low/ compared with
that of the sewage treatment plant (Nitrogen removal:  32%, Phosphorus
removal:  49.9%).  However, their values were reasonable, judging from
the quantity of removal.
when no detergents were added,  various types of surfactants were
detected in the effluent and activated sludge.   Especially, in the
activated sludge, CTAS and fatty acid salts were detected at a high
concentration.
     Fig. 7 shows the change with time in TOC and surfactants present
in the aeration tank.
     In the aeration tank, both are similar to the removal pattern of
substrates that are liable to be comparatively utilized as activated
sludge.
     For the biota in the activated sludge of this experiment, micro-
scopic examination could be conducted for 12 genera - mainly
Epislylis, Vorticella, Litonotus, Aonoeba and Rotifera.
     The fauna in the steady state of each experimental apparatus is
as shown in Table 12.  Rhizopoda comparatively often appeared in any
condition.  Aspidisca appeared when no detergents were added or
powdered soap and nonionic synthetic detergents were added.  But they
were not seen when anionic synthetic detergents and Zeolite deter-
gents were added.  This tendency was seen for Opecularia.  Epistylis,
Vorgicella appear in any condition.  Although the reason might be
SRT of 10 days or more, Rollfera and Nematoda appeared comparatively
often.
     The population was 1,700 ^ 3,600 N/m£ when no detergents were
added, and was almost the same degree except for the case of powdered
soap.  On adding powdered soap, the population was 3,700 ^ 4,300 N/m£
and very large with other cases.
     As  for filamentous bacteria,  its population was  smallest
of these five conditions when anionic synthetic detergents were
added.   In the other cases, they appeared to such a degree that they
occupied 30 ^ 60% in floe of activated sludge.
                                 414

-------
             Table  9  Operation conditions of experimental units
Unit
Detergents
Influent
(mg/£)
Aeration
tank
BOD
COD
TOC
K-N
T-P
pH*
DO*
(mg/£)
SVI**
MLSS
(mg/£)
MLVSS
MLSS
As***
(g/day)
SRT
(day)
BOD-SS
loadings
(g/g.day)
COD-SS
loadings
(g/g.day)
A
Control
108.6
53.3
58.5
19.24
5.20
6.7V7.4
7.7
73
1,645
0.87
14.4
11.4
0.22
0.11
B
Powdered
washing
soap
156.9
65.7
75.9
19.22
5.43
6.7^7.4
7.1
134
2,120
0.88
28.4
7.46
0.25
0.10
C
Nonionic
synthetic
detergent
141.2
68.6
70.3
19.48
5.08
6 . 3^7 . 2
7.6
73
1,960
0.86
19.2
10.2
0.24
0.12
D
Anionic
synthetic
detergent
136.2
62.0
63.6
20.1
6.56
6.6V7.4
7.4
106
1,841
0.85
13.5
13.6
0.25
0.11
E
Zeolite
containing
detergent
124.1
60.4
59.5
19.69
4.99
6 . 7^7 . 4
7.4
110
1,885
0.85
15.7
12.0
0.22
0.11
Note:  *   Measured in the middle of aeration tank
       **  Measured at the end of aeration tank
       *** Generated activated sludge
                                  415

-------
              Table 10  Water quality of effluents
Unit
Detergents
Water
quality
of
effluents
Removal
(%)
Turb. (cm)
SS (mg/&)
BOD
(mg/i)
COD
(mg/£)
TOC
(mg/£)
K-N
(mg/£)
T-P
(mg/£)
rp*l
S*2
T
S
T
S
T
T
NH*-N(mg/£)
NOT-N*3
(mg/£)
O-P
(mg/£)
BOD
COD
TOC
T-N
T-P
T
T
T
T
T
A
Control
45
7.9
2.3
2.3
9.6
7.9
5.0
4.5
1.24
4.37
0.68
13.88
4.18
97.8
82.1
91.4
21.4
16.0
B
Powdered
washing
soap
74
5.8
3.5
1.3
8.9
7.3
5.8
5.2
1.15
3.92
0.31
12.45
3.51
97.8
86.3
92.4
29.2
28,5
C
Nonionic
synthetic
detergent
40
7.7
3.2
0.3
10.3
7.2
5.0
4.7
0.69
4.30
0.41
14.66
4.03
97.7
84.9
92.9
21.2
15.4
D
Anionic
synthetic
detergent
35
10.3
3.7
1.4
14.0
10.0
5.9
5.5
1.10
5.40
0.76
13.51
4.96
97.2
77.4
90.7
27.3
17.7
E
Zeolite
containing
detergent
50
6.8
4.0
1.0
9.6
6.9
4.4
4.0
0.60
4.21
0.51
15.55
3.90
96.3
34.1
92.6
13.0
15.6
NOTE:  *1 Total



       *2 Soluble  (GFB)



       *3 NoT-N:   (NO2+NO3)-N
                                     416

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Table 11  Surfactant concentration in water samples and mixed liquor
Unit
Detersents
Influent
(mg/£)
Effluent
(rng/A)
Mixed
liquer
(mg/£)
MBAS
CTAS
Fatty
acid
salts
MBAS
CTAS
Fatty
acid
salts
MBAS
CTAS
Fatty
acid
salts
A
Control
0.03
0.03
0.10
0.27
0.17
0.54
1.96
23.9
24.1
B
Powdered
washing
soap


60.6


3.25


59.5
C
Nonionic
synthetic
detergent

13.5


0.47


29.2

D
Anionic
synthetic
detergent
10.3


0.35


6.67


E
Zeolite
containing
detergent
6.0


0.79


6.42


                                417

-------
en
   20-
             Unit A:  Control
                                o TOG
e
— 0L
a

	 1 	 1 i 	 1 	
0 20 40 60 80
is
en
•a 60-
o
d
Fattv
TOC(mg/«.)
to A
0 O O
f 1
Unite B: Powdered

o
0 o
•
o
0 20 40 60 80
Time
~ 40 '
X
_g
2 20 "
0
Unite C: NOnionic
° o TOC
• CTAS
o
0 20 40 60 80
Time
_ 40 -
1
y 20 -
0

100 120 140 160 180 200

Time (minutes )
washing soap
o TOC
• Fatty acid salts
o ° ° o 0 °

100 120 140 160 180 200
(minutes )
synsetic detergent


? « 9 9 °. 9
•10 _
I
w
0
100 120 140 160 180 .200
(minutes )
Unit D: Anionic synthetic detergent
o TOC
o
• MBAS
• O
o o o
.
0 20 40 60 80
Time
0 o ° o o o
• • • • • •
• 10 _
1
' 5«
CO
0
100 120 140 160 180 200
(minutes)
40 Unit E: Zeolite containing detergent
\
£ 20
^
0
0 o TOC
• MBAS
•
°. 9 & 9
0 20 40 60 80



* a $ 
-------
     These results revealed that,  in the biota of activated sludge,
there was almost no difference between the cases when detergents were
added and not added, and the population was almost the same except
for powdered soap.  Filamentous bacteria had a poor appearance
rate when anioinic synthetic detergents were used, but in other cases
they appeared to a considerable extent.  In case of powdered soap,
the population was larger than that of other conditions.
           Table 12  Microorganisms in activated sludge
,_ 	
Fauna \ Unit
Amoeba
Arcella
Eugl ypha
Chilodonella.
Litonotus
Aspidisca
Euplotes
Epistylis
Vorticella
Opercularia
Carchesi urn
Zoothamnium
Vaginicola
Acinata
Tokophrya
Lecane
Rotaria
Lepadella
Trichocerca
Diplogaster
Nais
Unknown
Population
(N/m£)

A
50% 300
25% 425
25% 175

200
25% 375
25% 50
50%2,300
75% 725
25% 50

150

50

145% 500
25% 50
25% 100

125% 425
75
25% 250
1,700%3,600

B
100%2,225
25% 325
25% 75
50
25% 400
50% 400

25% 975
150%1, 925
325% 625

775
25
25% 50

50% 400



25% 150

25% 125"
3,700%4,300

C
50% 750
75% 225
25% 350
25
25% 175
225

25%1,150
275%3,850
100% 175




25
125% 450

25% 100

25% 200

50% 250
1,800%3,200
	
D
125%1, 125
425% 650
25% 100

125% 650

25
25% 325
175% 800






325%1,150
25
300
75
25% 250

75
1,900%3,900

T?
125%1, 425
300%2,575
25% 275

50% 325

25
25% 600
70% 650
50
25

25
25% 50
25
100% 650


25
25% 625
25
50% 75
1,400%3,200

                               419

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5.2.3  Summary
            Under  the  operational  conditions of  the  conventional activated
       sludge  process,  the  experiment was conducted  by adding 48 mg/£ of
       powdered soap,  14 mg/& of nonionic synthetic  detergent, 14 mg/& of
       anionicanionic  synthetic detergent and 8  mg/& of Zeolite-containing
       detergent to  synthetic sewage, and the following results were
       obtained:

       1)   From the  viewpoint of the operation of the experimental apparatus,
           it  was  noted that powdered soap and Zeolite-containing detergent
           markedly  solidified in  the sewage.  Accordingly, it was suggested
           that in actual facilities those detergents were liable to pre-
           cipitate  into the sewer system or run into the plant as SS, so
           that their  removal in a primary sedimentation tank would be high.

       2)   Zeolite-containing detergent  tested brought about a remarkable
           forming reaction in the aeration tank.  We had some difficulties
           in  the  maintenance and  control of the apparatus.  Such problems were
           caused  by the kinds of  surfactants containing in detergents.

       3)   Judging from the properties of activated  sludge and the water
           quality of  effluents, no adverse influence of detergents upon
           the activated sludge treatment was found.  Further, there was
           no  tendency  for  surfactants to accumulate in the activated
           sludge.   The concentration of surfactants in effluents was  low,
           so  that the  surfactants were  apparently biodegraded by the
           activated sludge.

       4)   The fauna in the activated sludge was similar on these five
           conditions.  In  the case of powdered  soap, the population became
           larger  than  in other cases.   Felamentous  bacteria had poor  ap-
           pearance  when anionic synthetic detergents were used.
                                      420

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5.3  EXPERIMENT FOR TREATMENT OF DETERGENTS  ADDED TO MUNICIPAL SEWAGE

          This experiment was conducted to investigate the  influence of
     detergents upon the activated sludge treatment.  The detergents added to
     municipal sewage were phosphate-containing anionic synthetic  detergents,
     phosphate-free anionic synthetic detergents (containing Zeolite),
     phosphate-free nonionic synthetic detergents and powdered soap.

 5.3.1  Method

        (1)   Apparatus and operation

                  In this experiment, as shown in Fig. 8, 5 units for activated
             sludge treatment were used.  Samples were a municipal sewage  (control)
             and municipal sewages in which detergents were added.  As municipal
             sewage, the primary effluent was used  in the treatment plant of the
             river basin sewerage system, and the return sludge in the same  treat-
             ment platn was used as seed sludge.
                  The sewage storage tank was supplied with sewage every two
             days  (about 11 p.m.) and at the same time detergents were added.
             The supply of sewage from the sewage storage tank to the
             aeration and sedimentation tank was conducted four times a day,
             and the amount of sewage supplied was  10 £ per one time.  The super-
             natant liqour in the aeration and sedimentation tank was auto-
             matically drained into the effluent storage tank after the
             completion of sedimentation.  Aeration and sedimentation were
             conducted four times a day, one aeration period being four hours
             and one sedimentation period two hours.
                  The BOD-SS loadings in the aeration and sedimentation tank
             was set at 0.2 ^ 0.4 kg/MLSS.kg.day.
                  The analysis of water quality was conducted for the sewage
             in each sewage storage tank, the effluent in each effluent
             storage tank and MLSS in each aeration and sedimentation tank.
                                        421

-------
         Sewage
         storage
         tank
         (100 £)
Aeration and
sedimentation tank
Effluent
storage
tank
(100 £,)
                Fig.  8  Activated sludge unit
(2)   Detergents  used  in this  experiment

          The detergents used in  this  experiment are as  follows:

     Detergent A    :   Phosphate-containing anionic  synthetic
                       detergent,  MBAS content is 38% per solid
                       matter

     Detergent B    :   Phosphate-free  anionic synthetic  detergent
                       containing synthetic Zeolite, MBAS content is
                       32% per solid matter

     Detergent C    :   Phosphate-free  nonionic synthetic detergent,
                       CTAS contents is 24%,  MBAS is 2.2%

     Powdered soap D:   Phosphate-free  fatty acid type surfactant,
                       fatty acid salts is 70%

(3)   Dose of detergents

          It is  said  that the average  concentration of MBAS (per
     day) flowing into a Municipal treatmetn plant is 5 ^ 10 mg/£,
     and the average  concentration of  MBAS in influent in a treatment
     plant for a housing area is  10 ^  20 mg/&.
                                422

-------
     Therefore, the MBAS concentration in sewage for the experiment
     was  set at 10 mg/£ and 20 ing/ft, so as to correspond to the
     actual values.  The value in a high concentration of MBAS was
     set  at 50 mg/£.
         Municipal sewage originally contains 4^6 mg/£ of MBAS, so
     appropriate amounts of detergents containing  5 mg/£, 15 mg/£ and
     45 mg/£ of MBAS respectively were added to make their respective
     concentrations to 10 mg/£,  20 mg/£ and 50 mg/£.  The amount of
     nonionic surfactants added  was set at almost  the same level as
     that of MBAS.  In the case  of powdered soap,  amounts of soap
     corresponding to 15 mg/£, 45 mg/£, 105 mg/£ of fatty acid salts
     respectively were added.

(4)   Samples

         Samples prepared are as  follows

     Sewage No.l:  Primary sedimentation effluent  (control)
     Sewage No.2:  Sewage No.l + Detergent A
     Sewage No.3:  Sewage No.l + Detergent B
     Sewage No.4:  Sewage No.l + Detergent C
     Sewage No.5:  Sewage No.l + Powdered soap D
     Effluent Nos.1^5  correspond  to  Sewage Nos.1^5  respectively

(5)   Experimental period

         The experimental period was determined to be about 5 months.
     According to the concentration of surfactant, this period was
     divided as follows:  Table  13 shows the results of analysis  for
     test detergents.

     i)   Run I  (October  2 ^ November  25)

             As the surfactant  in detergents, 0.5 mg/£ of synthetic
         detergent and 0.8 mg/£  of powdered soap were added, and
         the amounts added were  gradully increased to 5 mg/£
         and 15 mg/£ respectively.

                                   423

-------
      During the period from 5 November to 25 November activated
      sludge acclimated the detergents to 5 mg/£ and 15 mg/£.

 ii)  Run II  (November 26 ^ January 10)

           As the surfactant in the detergents,  7 mg/£ of
      synthetic detergents and 2 mg/£ of powdered soap were added.
      Then,  the amount added was gradually increased to 15 mg/£
      and 45 mg/£ respectively.  It was for the  period from
      November 26 to January 10 that activated sludge acclimated
      the detergents to 15 mg/£ and 45 mg/£ respectively.

iii)  Run III (January 12 ^ March 19)•

           As the surfactants in the detergents, 20 mg/£ of
      synthetic detergents and 55 mg/Jl of powdered soap were
      added.  Then, the amount added was gradually increased.
      As the surfactant in the synthetic detergents, 45 mg/£ of
      synthetic detergent was added.  Then, due to foaming, it
      became impossible to increase the concentration any more,
      so the amount added was limited to 45 mg/£.  In the  case of
      powdered soap, the limit was set at 105 mg/£.  During the
      period from February 23 to March 19 activated sludge
      acclimated the detergents to 45 mg/& and 105 mg/£  .
                                424

-------
                     Table 13  Analysis of detergents
\ Item
Detergents\
A
B
C
D
Solid
(w/w %)
88.6
94.6
-
93.9
BOD5*
(mg/A)
147
176
186
1300
CODMn*
(mg/A)
80
79
78
240
TP
(%)
7.36
0.02
0
0
TOD
(%)
69.8
58.4
67.9
115
MBAS
(%)
38
32
22
0
           Note:
Measured 0.1% water solution of detergents
5.3.2  Results and discussion

            The  results  for  the perriod when activated  sludge  acclimated
       the  detergents  under the conditions of Run  I,  II  and  III have  been
       collated.

       (1)   BOD

                 With  the increase in the  amount of detergents  added, BOD
            of sewage  increased and average  BOD of sewage No.5  to which
            powdered soap had been added,  was higher than that  of other
            sewage.  Especially, average BOD of sewage No.5  in  Run III,
            III,  as the powdered soap corresponding to 105 mg/Jl  as surfact
            ant was added, was 313 mg/i and  a little over 2.7 times the
            114 mg/H of average BOD of sewage No.l to which  no  detergents
            had been added.
                 Table 14 shows BOD of sewage and  effluents. The average
            of activated  sludge effluent in  Run III was  5.4  mg/£ for No.2,
            No.2, 6.0  mg/H for No.3,  7.1 mg/£ for  No.4 and 9.1  mg/& for No.5.
            If they are compared with 5.5  mg/£  of  average BOD of Effluent
            No.l, there is no marked difference.
                 Accordingly, by adding detergents to sewage, the BOD in
            sewage was increased,  but there  was no tendency  for effluent
            BOD to rise.
                                     425

-------
   Table  14  BOD measurement of influents and effluents
                                                     (Unit:  mg/£)
Sample
No.l
No. 2
No. 3
No. 4
No. 5
Run I
Influ-
ent
81
91
81
82
104
Efflu-
ent
3.3
3.5
4.4
4.0
3.8
Re-
moval
96
96
95
95
96
Run II
Influ-
ent
96
101
103
101
169
Efflu-
ent
4.2
4.9
7.2
5.8
5.4
Re-
moval
96
95
93
94
97
Run III
Influ-
ent
114
154
153
162
313
Efflu-
ent
5.6
5.4
6.0
7.1
9.1
Re-
moval
95
96
96
96
97
(2)   COD
          When the  amount  of  detergents  added  is  small,  there  is
     no  marked difference  between the  COD of sewage  No.l and the
     COD of Nos.  2^4.  However,  when the amount became large as
     Run III,  the COD of sewage Nos.   2^5 was a little higher
     than that of sewage No.l.   (See Table 15.)
                            426

-------
  Table 15  COD measurement of influents  and effluents
                                                    (Unit:   mg/£)
Sample
No.l
No. 2
No. 3
No. 4
No. 5
Run I
Influ-
ent
41
42
41
41
42
Efflu-
ent
9.5
11.7
10.4
11.8
10.6
Re-
moval
77
72
75
71
75
Run II
Influ-
ent
46
48
48
54
55
Efflu-
ent
11.2
12.4
12.1
12.3
12.0
Re-
moval
76
74
75
77
78
Run III
Influ-
ent
66
76
76
100
93
Efflu-
ent
11.4
18.8
17.9
18.8
16.1
Re-
moval
83
75
76
81
83
          The average  COD in effluent Nos.  2  ^ 5  is  not  remarkably
     different from that of Effluent No.l  in  Run  I and II.
     The average COD of effluent in Run III sre 18.8 mg/Jl for No.2
     17.9 mg/£ for No.3, 18.8 for No.4 and 16.1 mg/£ for No.5, and
     they were a little higher than 11.4 mg/£ of  average BOD of
     effluent No.l.
          Accordingly, when the amount of  detergent  added was
     increased,  the COD of sewage increased and the  COD  of  effluent
     became  somewhat higher than that of effluent to which  deter-
     gents had not been added.
(3)   TOC
         As  the  amount of detergents  increased,  the  TOC  in  sewage
     Nos. 2^5 increased.   (Run  III)
         The average values of TOC  in effluent Nos 2^5 were  not
     much different  from  the value of  effluent No.l in  Run  I and
     II  in which  a small  amount of detergents were added. The  averege
     values of TOC of each effluent  in Run  III were 15.2  mg/£ for
     No.2, 15.7 mg/£ for  No.3, 15.9  mg/£  for No.4 and 13.9 mg/£ for
     No.5.  They  were'a little higher  than  7.8 mg/£ of  the average
     TOC of effluent No.l.
                            427

-------
          Accordingly, when  the amount of detergents added was
     increased,  TOC in sewage  increased,  and TOG  of effluents became
     a little higher,  compared with that  of effluent to which detergents
     had not been added.    (Run III)

   Table 16   TOC measurement of influents and effluents
                                                    (Unit:  mg/£)
Sample
No.l
No. 2
No. 3
No. 4
No. 5
Run I
Influ-
ent
42.5
44.2
44.5
45.0
49.2
Efflu-
ent
5.7
6.8
7.2
7.6
7.3
Re-
moval
87
85
84
83
85
Run II
Influ-
ent
53.4
62.4
66.2
70.1
77.9
Efflu-
ent
11.7
13.9
14.4
15.1
14.5
Re-
moval
78
78
78
78
81
Run III
Influ-
ent
66.1
84.7
86.6
104.0
126.2
Efflu-
ent
7.8
15.2
15.7
15.9
13.9
Re-
moval
88
82
82
85
89
(4)   Suspended solids

          The  sewages  in  which  the  SS  concentration increased due to
     the  addition of detergents were  sewage  No.3  (Run  III)  and No.5.
     The  cause for No.3 is  considered  to be  due to the synthetic
     Zeolite contained in detergents.   The cause  for No.5  is con-
     sidered to be due to the fatty acid salts contained in powdered
     soap D and to the so-called soap  scum affected by the sewage.
     (See Table 17.)
          The  average  concentration of effluents  Nos.  2^5 was not
     much different from  that of effluent No.l.   The average con-
     centrations of SS of effluents in Run III were 19 mg/£ for No.l,
     3.9  mg/£  for No.2,  6.4 mg/£ for  No.3, 5.0 mq/l for No.4 and
     5.4  mg/fc  for No.5.
                             428

-------
          Therefore,  when synthetic Zeolite-containing detergents and
     powdered soap were added to the sewage,  the SS concentration
     increased,  but the addition of other detegents did not bring
     about the increase of suspended solids.   The SS concentration of
     effluents,  composed of the above sewage  processed through
     activated sludge treatment, did not increase.

    Table 17  SS measurement of influents nad effluents

                                                    (Unit:   mg/Jl)
Sample
No.l
No. 2
No. 3
No. 4
No. 5
Run I
Influ-
ent
53
48
49
47
56
Efflu-
ent
2.6
6.2
4.1
5.3
3.7
Re-
moval
95
87
92
89
93
Run II
Influ-
ent
53
47
48
52
73
Efflu-
ent
3.7
3.7
3.9
4.9
3.3
Re-
moval
93
92
93
91
95
Run III
Influ-
ent
82
80
117
80
157
Efflu-
ent
1.9
3.8
6.4
5.0
5.4
Re-
moval
98
95
95
94
97
(5)   MBAS
          The  sewages  in which MBAS was  increased by  the  addition of
     detergents  were sewage  No.2 ^ No.4  (Run.  III).   Especially,
     MBAS  of sewage Nos. 2 and 3 was  50.1  mg ,  which  was  about ten
     times that  of sewage No.l (5.1 mg/£).   The reason why MBAS was
     so  high was that  the detergents  containing anionic surfactants
     were  added.  (See Table 18.)
          The  average  value  of MBAS in effluent Nos.2^5 was not
     much  different from that of effluent  No.l.   The  average MBAS
     values of effluents Run III were 0.09  mg/H for No.l
     0.54  mg/£ for No.2, 0.42 mg/£ for No.3,  0.05 mg/£ for No.4 and
     0.10  mg/Jl for No.5.
                             429

-------
  Table 18   MBAS  measurement  of  influents  and  effluents
                                                     (Unit:   mg/Si)
Sample
No.l
No. 2
No. 3
No. 4
No. 5
Run I
Influ-
ent
5.5
10.5
10.5
6.0
5.5
Efflu-
ent
0.08
0.12
•0.13
0.07
0.09
Re-
moval
99
99
99
99
98
Run II
Influ-
ent
6.2
21.2
21.2
7.5
6.2
Efflu-
ent
0.10
0.21
0.28
0.29
0.14
Re-
moval
98
99
99
96
98
Run III
Influ-
ent
5.1
50.1
50.1
9.3
5.1
Efflu-
ent
0.09
0.54
0.42
0.05
0.10
Re-
moval
98
99
99
99
98
(6)   Total  phosphorus

         The  sewage of which  the  total  phosphorus  was  increased by
     the  addition  of detergents was  sewage  No.2.  Especially  in
     Run  III,  its  concentration was  12.8 mg ,  which was about
     3.2  times that of sewage  No.l.   The phosphorus
     concentration of  other sewages  to which phosphate-free deter-
     gents  were added, was almost  the same  with that of sewage No.l.
     (See Table 19.)
         The  average  concentration  of the  total phosphorus in
     effluents was not much different from  that of  effluent No.l,
     except for No.2.   The average concentrations of the total
     phosphorus of effluents in  Run  III  were 1.40 mg/£ for
     No.l,  9.02 mg/£  for  No.2, 0.83  mg/£ for No.3,  0.64 mg/£ for
     No.4,  0.48 mg/£  for  No.5.
                           430

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   Table 19  TP measurement of  influents  and  effluents
                                                     (Unit: mg-P/£)
Sample
No.l
No. 2
No. 3
No. 4
No. 5
Run I
Influ-
ent
3.37
4.24
3.23
3.26
3.25
Efflu-
ent
1.54
2.36
1.48
1.63
1.40
Re-
moval
54
44
54
50
57
Run II
Influ-
ent
3.17
5.81
3.15
3.13
3.15
Efflu-
ent
1.37
3.63
1.34
0.70
0.45
Re-
moval
57
38
57
78
86
Run III
Influ-
ent
4.03
12.8
3.98
3.97
3.80
Efflu-
ent
1.40
9.02
0.83
0.64
0.48
Re-
moval
65
30
79
84
87
(7)   Total  nitrogen

         The  addition of detergents did not bring about an  increase
     in  the total  nitrogen  in  the sewages.  Their concentration was
     almost the  same  as that of  sewage No.l.   (See Table 20.)
         The  average concentration of the  total nitrogen  in
     effluents,  except for  effluent No.5 in Run III, was not much
     different from effluent No.l.No.l.
         In order to keep  activated sludge in a favorable condition,
     it  is  said  that  a nutrient  ratio such  as BOD : N  : P  =
     100 :  5 : 1 is required.  When the removal rate of BOD  is
     increased,  the removal rates of nitrogen and phosphorus increase
     according to  this proportion.  The BOD removal of No.5  in
     Run III was 304  mg/&,  which was higher than that  of
     other  sewages (No.l:   108 mg/£ , No.4:  155 mg/£, etc.)
     For this  reason, the nitrogen in Run III is considered  to
     have decreased.
                           431

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             Accordingly, the addition of detergents to the sewage did
        not bring about a change in the total nitrogen in the sewage.
        The nitrogen contents of effluents were almost the same when
        the BOD removal was not high.

       Table 20  TN measurement of influents and effluents
                                                        (Unit:  mg/£)
Sample
No.l
No. 2
No. 3
No. 4
No. 5
Run I
Influ-
ence
21.4
21.3
23.7
22.3
22.4
Efflu-
ence
17.6
18.0
18.5
18.2
16.2
Re-
moval
18
15
22
18
28
Run II
Influ-
ence
23.3
23.7
22.5
22.6
21.6
Efflu-
ence
16.4
16.9
16.9
15.6
13.7
Re-
moval
30
29
25
31
37
Run III
Influ-
ence
30.6
31.0
31.9
31.6
30.4
Efflu-
ence
22.2
22.9
23.5
20.8
13.7
Re-
moval
27
26
26
34
35
(8)   Properties  of  activated  sludge
     i)   Population of Protozoa
              The number of microorganisms  in  activated  sludge repeatedly
         increased  and decreased during the experiment,  but the addition
         of  detergents did not cause the microorganisms  to became extinct
         or  unbalanced in distribution.  Among the microorganisms, the
         dominant species are Peritricha such  as Vorticella
         Epistylis.  The population in Run  III  is shown  in Tables
         21  and  22.
              Accordingly, when detergents  are used within the normal
         range it is considered that they do not have  an adverse influ-
         ence  on the microorganisms conducting biological treatment.
                               432

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Table 21  Population of microorganisms in activated sludge
                                       (Unit: N/m£)
Date
Samples
Peritricha
Aspidisca
Litonotus
Suctoria
Rotifera
Nema toda
Ciliata
(swimming type)
March 10
No.l
6440
2510
420
40
130
70
20
No. 2
2000
40
530
-
20
20
-
No. 3
2160
20
690
-
-
-
-
No. 4
2380
200
420
-
40
20
200
No. 5
19700
360
980
-
160
130
-
Table 22  Population of microorganisms  in  activated sludge




                                        (Unit:  N/mJl)
Date
Sample
Peritricha
Aspidisca
Litonotus
Suctoria
Rotifera
Nematoda
Ciliate
(swimming type)
March 16
No.l
5250
5950
500
-
250
50
-
No. 2
10100
150
1750
-
150
150
-
No. 3
3950
-
200
-
-
50
-
No. 4
7600
-
4160
-
40
160
960
No. 5
26700
2180
18000
-
250
470
. 180
                          433

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 ii)  MLVSS/MLSS

           The average values of MLVSS/MLSS and SVI of activated
      sludge, measured during the experiment,  are shown in Table
      23.  MLVSS/MLSS of Sample No.1,  to which detergents had not
      been added,  was 66 ^ 74%.  MLVSS/MLSS of sample No.3,  to
      which detergent B containing Zeolite was added, in Run
      III fell to  60%.  In Sample No.5,  to which powdered
      soap had been added, MLVSS/MLSS  rose to  80% in Run
      II.  MLVSS/MLSS of No.2 and No.4 were 70 % 80% and 74 % 77%,
      respectively.  They were not much  different from Sample I.
           Accordingly, when  synthetic detergents are used within
      the normal range, the proportion of MLVSS/MLSS in the
      activated sludge cannot be considered to alter remarkably.
      However, if  synthetic detergents for washing are converted
      to powdered  soap, the proportion of MLVSS/MLSS will increase
      to a certain degree, even when the soap  is used within the
      normal range.

iii)  SVI

           Due to  the characteristics  of sewage used in this
      experiment,  SVI of Sample No.l,  to which detergents had not
      been added,  was lower than SVI of  the activated sludge
      in an ordinary treatment plant.  SVI of  the activated sludge
      in this experiment was  also low.  (See Table 23.)
           SVI of  sewage No.l was somewhat low compared with that
      of Sample 1  when the amount added  was increased.  In case of
      nonionic synthetic detergents and  powdered soap, when the
      amount added was increased, there  was a  tendency for SVI to
      increase.
                               434

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       Table 22  MLVSS/MLSS and SVI measurement of activated sludge
Sample
No.l
No. 2
No. 3
No. 4
No. 5
^^\^ Run
Iteiri-1--^
MLVSS/MLSS
SVI
MLVSS/MLSS
SVI
MLVSS/MLSS
SVI
MLVSS/MLSS
SVI
MLVSS/MLSS
SVI
I
66%
65
71%
57
68%
69
75%
57
68%
71
II
74%
51
80%
56
69%
58
74%
56
81%
101
III
73%
67
70%
48
60%
47
77%
101
87%
86
5.3.3  Summary
            The experiment for the activated sludge process was conducted
       by adding detergents to municipal sewage.
            The results were as follows:

       (1)   When the detergent corresponding to 15 mg/& of surfactant
            (45 mg of powderd soap)  was added to sewage (containing 4  ^
            7 mg/£ of MBAS), the concentrations of BOD, TOC, suspended
            solids (powdered soap added),  MBAS (anionic synthetic detergent
            added), and the total phosphorus (phosphate-containing synthetic
            detergent added) of the sewage somewhat increased,  compared
            with those of non-added sewage.  However,  no influence was
            found upon the water quality of effluents.

       (2)   When the detergent corresponding to 45 mg/il of surfactant
            (105 mg of powdered soap)  was  added to sewage, the  concentrations
            of BOD, COD,  TOC,  suspended solids,  and MBAS of the sewage
            increased.
                                     435

-------
     COD,  TOC,  and  total phosphorus  (phosphate-containing  synthetic
     detergent  added) of the effluent  tended to somewhat increase in
     comparison with  those of  the effluent  from sewage No.l.

(3)   Microorganisms in  activated sludge,  even  though detergents were
     added to the sewage, did  not become  extinct or unbalanced in
     distribution.  MLVSS/MLSS of the  sludge to which a detergent
     containing Zeolite had been added somewhat fell to 60%.  MLVSS/
     MLSS  of the sludge to which powdered soap had been added rose to
     80% as the amount  added was increased.  The MLVSS/MLSS of the
     activated  sludge to which other detergents had been added was
     70 ^  80%.  The values were not much  different from that of the
     sludge to  which  detergents were not  added.
          SVI of activated sludge tended  to be lowered when the
     amount of  anionic  synthetic detergents added was increased.
     SIV of the samples to which nonionic synthetic detergents or
     powdered soap  had  been added, tended to rise.
          From  the  above results, it can  be said that there is no
     serious influence  of detergents upon the  activated sludge and
     the water  quality  of effluents when  they  are used within the
     normal range,  but  there is a possibility  that the water quality
     will  deteriorate when a large quantity of detergent is used.
                                 436

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6.   CONCLUSIONS

          To clarify the influence of detergents  upon the  sewerage  system,  a
     field investigation at sewage treatment plants and laboratory  experi-
     ments have been conducted.   The results are  as follows:

     (1)   For the concentration  of surfactants  in influent, MBAS  was  2.5  ^
          6.4 mg/H (average 4.7  mg/Jl) ,  CTAS  1.9 ^4.7 mg/i (average 3.1 mg/£) ,
          and fatty acid salts 2.4 ^ 6.7  mg/£ (average 4.1 mg/£) .  This MBAS
          concentration is  almost an average value in municipal sewage.
               For the concentration of surfactants in primary sludge, MBAS
          was 3.8 mg/g on an average,  CTAS  3.0  mg/£ on an  average and fatty
          acid salts 96.9 mg/g on an average.
               For the concentration of surfactants in waste  activated sludge,
          MBAS was 3.4 mg/g on an average, CTAS 19.7 mg/g  and fatty acid  salts
          47.2 mg/g.  It was considered that the  high concentration of CTAS
          and fatty acid salts in activated  sludge was due to the influence
          of factors other  than  detergents.

     (2)   The biodegration  of DBS as a  type  of  LAS is affected by DO  level  in
          aeration tanks in case of high  concentration of  DBS.  When  DBS  of
          14.5 mg/£ or less as MBAS is  added, no  adverse effect on  the water
          the water quality of effluent is found  in either high DO  condition
          or low DO condition.   However,  when the DBS of 29 mg/£  in terms of
          MBAS is added,  MBAS remains  in  the effluent under low DO  condition.

     (3)   Using the samples prepared by adding  detergents  to  synthetic sewage
          or municipal sewage, an activated  sludge treatment  experiment was
          conducted,  and the following  results  were obtained:

          o   Even if the concentrations of MBAS,  CTAS,  and fatty  acid salts in
             test sewage were set to 20 mg/£, 20  mg/£ and  50  mg/£ respec-
             tively,  water  quality was  almost the same as  in  the  control
             system.   However, when the concentrations of  MBAS, CTAS, and
             fatty acid salts were set  to 50 mg/£,  50 mg/£, and 110 mg/£
             respectively,  the water quality of effluents  was somewhat
             deteriorated.
                                      437

-------
       o  The fauna in activated sludge to which detergents had been
          added was the same as that of the control system.  However,
          the population of microorganisms was larger in the powder
          soap-added system than in other systems.

       o  MLVSS/MLSS was around 65 '^ 77%.  As the concentration of
          Zeolite-containing detergent increased, MLVSS/MLSS fell to
          60% or less.
               Further, when the concentration of powdered soap
          increased, MLVSS/MLSS rose to 80%.

   (4)  It was concluded that MBAS, CTAS, and fatty acid salts behave
       as follows:
                                    96 ^ 98%
                                                     92 ^ 94%
MBAS, CTAS
comsumption
100%






Sewer


Primarv
sedimentation
tank


Aeration
tank


Final
trank


                                                           10%
                                    70 ^ 75%
65 ^ 70%
Fatty acid salts
comsumption










Primary
sedimentation
tank
30 ^ 40%


Aeration
tank


Final
sedimentation
trank


             MBAS  and CTAS  are  removed mainly by  aeration  tank.   On  the
        contrary,  fatty  acid  salts  are considerably  removed  by house
        inlets  and primary  sedimentation  tanks, so that  its  loadings to
        the  activated sludge  process  is 30 ^ 40%  of  the  consumption.
                                      438

-------
         (5)   Even if consumers convert from synthetic detergents to powdered
              soap, almost no influence on sewage treatment is anticipated,
              as long as the amount of detergents currently used is maintained.
              Further, it is concluded that detergents have no adverse effect
              on sewage treatment,  .if the detergent borne surfactant con-
              centration in sewage remains as low as it now is.

REFERENCES

(1)   Industrial Statistics of Japan Soap and Detergent Association

(2)   Sudo Byuichi, Jour. Water and Waste, (in Japanese) Vol.22,  No.4, pp27 ^
     34 (1980)

(3)   Yamane Atsuko et al., proceedings of the 15th Japan Water Pollution
     Research,  (in Japanese), pp40 ^ 41, 1981.
                                      439

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-------
                                       Eighth US/Japan Conference
                                                  on
                                       Sewage Treatment Technology
Fifth Five-Year Sewerage System Development Program and

Long-Range Prospects for Development of Sewerage Systems
                         October, 1981
                         Washington
   The work described  in this paper was not funded by the
   U.S. Environmental  Protection Agency.  The contents do
   not necessarily  reflect the views of the Agency and no
   official endorsement should be inferred.
      Tsutomu Tamaki

      Director,

      Department of Sewerage and Sewage Purification,

      Ministry of Construction
                            441

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1.  PREFACE
     With the enactment of the Sewerage Act in 1900 as impetus,  the
construction of modern sewerage systems began in Japan,  Under the
Sewerage Act, the responsibility for construction and control of sewerage
systems rests with municipalities.  It is stipulated in the act that
when a municipality is to construct a sewerage system, approval from the
competent minister (central government) is necessary.  Though the
Sewerage Act had been enacted, sewerage systems had been developed only
in a small number of cities before 1945 when World War II came to an end.
At that time, only Tokyo, Osaka, Kyoto, Nagoya and two other cities had
sewage treatment plants.
     After 1945 and in the 1950s, there was little progress in the
implementation of sewerage projects in Japan.  The level at which sewer-
age systems were diffused was very low.  The reason may be ascribed to
the following factors.
     (1)  Each household was equipped with a privy.  Night soil was
          carried off to farmland as manure.
     (2)  The necessity of sewerage systems was not well recognized.
     (3)  For any municipality, which was the mainstay entity for sewer-
          age projects, it was difficult to secure a financial source
          for the construction of sewerage systems.
     (4)  National policy was intended primarily to strengthen the
          basis of industry with measures for infrastructure such as
          sewerage to be made afterward.
     From the latter half of the 1950s to the 1960s when the Japanese
economy began to develop, however, the environment was progressively
aggravated, and the deterioration of river water quality on the outskirts
of urban areas was conspicuous.
     In contrast to advanced Western nations, Japan featured a strikingly
fast speed at which population became concentrated in urban areas (this
concentration is still in progress), rapid economic growth — particularly,
a high growth rate for industry — and a resultant conspicuous concentra-
tion of production and consumption in specific regions.  The consequence
was that water pollution markedly accelerated in the 1960s.
                                  442

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     With an area of about 370,000 km2, Japan is nearly as big as the
State of California.  The greater part of the national land is mountain-
ous.  Less than 25% of the total area is inhabitable but 113 million
people, equivalent to half of the total population of the United States,
live there.  For the reasons that have been introduced earlier, the
fact that practically no accumulation was made in terms of facilities
brought about a number of difficulties in the development of sewerage
systems.  As examples, it may be said that trunk, lateral, branch
sewers had to be buried in completely built-up areas with high popula-
tion densities in almost all the cities; that for environmental con-
siderations on the periphery, the costly shield construction method,
instead of the less costly open cut construction method had to be fre-
quently used in the construction of trunk sewers; that it was difficult
to acquire tracts of land for treatment plants; and that since the
water quality deteriorated at a faster pace than the development of
sewerage systems, it was necessary to have secondary treatment while the
construction of sewers was in progress.  The cost-effectiveness and per-
formance of sewerage systems were consequently affected to a considerable
degree by these facts.
     The sophisticated development of sewerage systems began in the latter
half of the 1960s when pollution of urban rivers was taken up as a social
issue.  That period coincided with the time when the confusion which had
marked the immediate postwar years more or less dissipated, driving the
people to take an interest in accumulating social overhead capital.  In
Japan, it was decided to carry out the development of sewerage systems
under a five-year program, as is the case with other public works projects.
Before the present or fifth five-year program started in fiscal 1981,
there have been four five-year programs.  Under the past four pro-
grams, ¥15,120 billion ($68.7 billion, with one dollar = 220 Yen) has
been invested in terms of prices prevailing in 1980.  When the first
five-year program started, the population covered by sewerage systems
was 7,090 thousand (with the coverage rate at about 7%), but by the end
of fiscal 1980, sewerage systems had been developed for 34,500 thousand
(with the coverage rate at 30%).  As to whether this figure is worth that
amount of investment, there might arise varied arguments according to the
                                   443

-------
American standard of judgment.  If you feel the value is high,  it should
be pointed out that the reason is attributable to specified circumstances
in which Japan is placed.  Be the matter what it may, it is a fact that
there have been sharp rises in the population for which sewerage systems
have been developed and in the amount of investment.   In 1971,  or 10
years ago, when the U.S.-Japan Conference on Sewage Treatment Technology
met for the first time, the population for which sewerage systems had
been developed stood at 17.5 million with ¥37.3 billion ($170 million)
invested per year, whereas the population for which sewerage systems had
been developed has increased to 34.5 million and the annual amount of
investment to ¥1,800 billion ($8.18 billion) by 1981.
     In Japan, there are needs for the nationwide development of sewerage
systems both in urban and rural areas as facilities indispensable for the
assurance of the national minimum for the people.  The Fifth Five-Year
Sewerage System Development Program started in fiscal 1981 with a total
investment of ¥11,800 billion ($53.6 billion), targeting to develop sew-
erage systems for 54 million (with a coverage rate of 44%).  As Japan
is likely to sustain a setback as in the case of other economies of the
world, optimism cannot necessarily be warranted as to whether this
total amount of investment may be sustained as scheduled.  But the fact
is that investment in sewerage systems is strongly supported by the
people and high hopes are pinned on a systematic development of sewerage
systems.

2.  THE PRESENT SITUATION OF SEWERAGE SYSTEMS
     Sewerage projects are carried out by local autonomous bodies as the
project entities in Japan.  Basically, there are two methods in which
sewerage projects are executed.  One is the method in which public
sewerage systems are developed by a municipality for itself.  In the
other method, treatment plants and trunk sewers are constructed and
maintenanced by a prefectural government to collect the sewerage from a
number of municipalities.  The latter is known as a regional sewerage
system.  It is adopted in areas where the built-up areas of cities
are linked together and for which the development of sewerage
systems will be of considerable effect in terms of cost-effectiveness
                                   444

-------
and conservation of the water quality of rivers,  etc.   In either case,
a project is carried out with a construction grant from the national
government.  One feature is that construction grants  from the  national
government for regional sewerage systems are higher than those for public
sewerage systems.  In addition, the improvement of urban drainways is
carried out as part of a sewerage system for preventing the flood of
urban areas, as these drainways are known as urban sewer conduits.
     In fiscal 1980, sewerage systems were constructed, with a total
outlay of about ¥1,800 billion ($8.18 billion).  In regional sewerage
systems, about ¥310 billion ($1.4 billion) was invested.
     Public sewerage projects were carried out in 695 municipalities in
fiscal 1980.  The relations between the population scale of municipalities
and the municipalities where a public sewerage project was performed are
shown in Pig. 1.  Public sewerage projects are being  conducted in about
one-fifth  of  all municipalities  in the nation.  Municipalities where a
public sewerage project has yet  to be carried out have  a population of
less than  50,000.   This suggests that the development of sewerage sys-
tems must be  stepped up positively for smaller municipalities.
     In areas where the development of sewerage systems is not under way,
wastewater and night soil are  treated by either on-site septictanks or
night soil purification plants.  Regional sewerage projects were per-
formed at  69  places throughout the nation in  fiscal 1980.  These pro-
jects are performed in 38 prefectures, encompassing as many as 600
municipalities.  Regional sewerage systems are developed in major cities
and their peripheries.  Plans  call for the coverage by regional sewer-
age systems of one-third of the total planned population.  The regional
sewerage system is  identical in some respects with the system used by
the County Sanitation District of Los Angeles in California but differs
from the Los Angeles system in the sense that construction and operation
are directly  conducted by prefectural governments, not by a board of
municipality.
                                  445

-------
     Number ot
     muni cipali( ies
3 , 1 00 -
3 , 000
500 -


400 -
300 -
200 -

1.00

3
=£









06
^









3
-
51



*,
<.-.,

*i






187
I
1
b
(Tfe



1 	 _ Number of municipalities
with treatment started
\ 	 _ Number of municipalities
with projects
_ Total number of
muni cipalitits



138 J.29




'// 45 45 44
, /// ,-p, 1010 10
' // \ v/\ t i1 -\n\
             Population  Population  Population  Population
             100         100^ 300   300'M, 000  1,000
             thousand    thousand    thousand    thousand
             and under                           and over
               Fig.  J   Execution  of Sewerage Projects
                       (as  of the end of  FY1980)
     The population covered by sewerage systems in Japan at present was
about 34.5 million as of the end of fiscal 1980 (March 1981),  and the
coverage rate to the total population was about 30%.   Half of  those
covered, or about 17 million people,  are provided with sewerage systems
in Tokyo, Osaka, Nagoya and eight other major cities.   In other words,
72% of the approximately 27 million people living in the 11 major cities
of Japan are using public sewerage systems.  The coverage rate for other
areas with a total population of about 90 million is low, and  only about
one-fifth (19.2%) are using public sewerage systems (Fig. 2).   As has
been mentioned earlier, this suggests that it is an urgent task to
develop  sewerage systems for smaller cities in future.
                                  446

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             100 -
              80 -
              60 -
              40 -
              20 -
Fig. 2
                72
                                      30
                           19
                   Designated  Other      National
                   cities      cities     mean
                   (11 large
                    cities;
              Coverage Rate of Sewerage Systems to Population
              (as of the end of FY 1980)
     Up to now, a total of about 81,000 km of sewers have been con-
structed, including about 43,000 km (54%) of combined sewers, about
11,000 km (13%) of sanitary sewers and about 27,000 km (33%) of storm
sewers.  Combined sewers are adopted by major cities and cities which
started construction earlier while the cities which started in the
last 10 years have almost unexceptionally adopted separate sewer systems.
The values above include those for sewers to be connected with plants
under construction.  It is estimated that about 80% of the 81,000 km
is actually in use.
          As of the end of fiscal 1980, 429 sewage treatment plants were
in operation and an additional 400 plants were under construction.  The
total capacity of the sewage treatment plants in operation is about
25 million m3 per day (6,250 mgd), and the daily maximum dry weather
flow is about 23 million m3 per day (5,750 mgd).  The rate of industrial
wastewater to the total flow is estimated at about 20%.  Almost all the
plants in operation are equipped with facilities for secondary treatment
by biological processes.  About 90% of them use the activated sludge
process (Table 1).  There have recently appeared increasing signs of the
use of the fixed growth type process such as with rotating biological
filters.  The effluent standard of the secondary sewage treatment process
is less than 20 mg/1 in terms of BOD,  but the quality of effluent is
better than this at most plants.
                                   447

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                                            Table  1  Wastewater Treatment Plants by Process
^""^^CLass
Planned Daily
Maximum Dry
Weather Flow
(thousand m3/d)
Less than 5
5-10
10-50
50-100
100-500
More than 500
Total
Pri-
mary
Sedi-
menta-
tion
4

1

1
6
Middle Class
High-
er h rate
ig Modi- Area-
rate , . , . .
_ . . fied tion
Trick-
n . Aera- and
^f tion Sedi-
Filter
menta-
tion
715
3 4
8 11
1 2
2

19 1 24
High Class
Conven- Con-
Fx t ^n ci ••
tional Step tact Pure Oxida-
Acti- Aera- Stabi- Oxy- tion RBC
vated tion . liza- gen Ditch
„•. -, tion .
Sludge tion
43 5 17 3 24 1
40 8 1
105 29 1 1
44 19
26 24
1 5
259 90 18 3 34 2

1980
Total
92
56
155
67
53
6
429
00
           NOTE:   The breakdown  of  429 wastewater treatment plans is as follows:
                  public  sewerage,  402 plants; regional sewerage, 25 plants; public sewerage for industrial
                  wastewater  2 plants.

-------
     It is a thorn in the side of Japan,  the national land of which is
limited, to dispose of sludge — and particularly,  to acquire places
for sludge disposal.  The total quantity  of sludge  generated is  estimated
at about 2.4 million m3 per year.  Of this amount,  45.0%  is land filled,
34.0% is used for coastal reclamation, 7.0% for dumping in the sea and
14.0% for use on farmlands.  Liquid sludge disposal,  as is done in the
United States, is not adopted in Japan at all.   All sludge is mechani-
cally dewatered and carried off to places of disposal in the form of
sludge cake or ash.  Incineration is performed in many places,
particularly major cities, to reduce volume.  About 40% of the sludge
generated throughout the nation is incinerated.  From the standpoint
of energy-savings, incineration presents  a problem, and it is to be hoped
that some substitute methods will appear.  In light of the insular nature
of Japan, it is argued in some quarters that ocean dumping should be
put into greater consideration while also ascertaining its'safety.  Fig.3
illustrates the present situtation of sludge disposal.  When the coverage
rate reaches about 44%, sludge production is estimated to exceed about
4.2 million m3 per year.
                        Ocean dumping, etc.  (7%)
  Effective use
  (14%)
   Coastal
   reclamation
   (34%)
                                                Land reclamation
                                                (45%)
                                             (Surveyed by  the  Ministry
                                              of  Construction)
     Fig.  3   Breakdown  of  Final Disposal  of  Generated  Sludge  (1980)
                                   449

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3.  FIVE-YEAR SEWERAGE SYSTEM DEVELOPMENT PROGRAMS IN THE PAST
     The systematic development of sewerage systems from the 1960s have
evolved under five-year programs, the first one of which started in 1963.
As has been introduced earlier, the year 1981 was the first year for the
Fifth Five-Year Sewerage Program.  In Japan, most public works are
carried out under a five-year program.  Five-year programs are formulated
with the concurrence of Government ministries and agencies in line with
the national economic program.  It is a practice to work out a national
economic program every five years, and in most cases to set up targets
for the development of the national economy in a given period of five
years.  The magnitude of investment in public works is determined by the
project, and investment is made in a well coordinated manner under this
program.  It is believed that Japan's economic development is an out-
come of the successful implementation of such five-year economic programs.
     The five five-year sewerage system development programs, of which
the first started in 1963, have been implemented on the basis of such
an economic program.  In the meantime, the emphasis in Japan's public
investment has shifted from infrastructure for industry to that for liv-
ing.  In this connection, investment in sewerage systems has increased
at a remarkably fast pace.  Fig 4 indicates changes in the rate of
investment in sewerage projects, the rate of investment to Gross National
Production (GNP) and the rate of investment to the formation by the
Government of fixed capital since 1958.  As is discernible from these
figures, there has been a sharp rise in the outlay for sewerage since
the latter half of the 1960s.  Particularly in the last 10 years, the
outlay has increased about tenfold.  When it is taken into account that
GNP has increased about 3.9 times and the formation by the Government
of fixed capital 4.7 times, it is evident that the rate of investment
in sewerage systems is extremely high.  The year 1974 witnessed an
economic setback due to the oil crisis, but there was no significant
drop in the rate of investment in sewerage systems.
                                 450

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(in thousand
 bill-ion yen)
(A)
   2.0 -
   1.8-
   1.6 -
   1.4-
   1.2 .
   1.0 -
   0.8 -
   0.6 J
   0.4 J
   0.2 .
 Fiscal
 year
 (in
 bill i or
 yen for
 project
 cost)
             Sewerage project cost
             (A)  in thousand million yen
             Sewerage project cost/GNP

             Sewerage project cost/Government's
             formation of"fixed capital
             (0)  %
'58
(10)
'63
(50)
 '67
(128)
 '71
(374)
 '76
(751)
 '79 (Year)
(1691)
            Fig.  4   Shares in Sewerage Project Cost, GNP and
                     Government's Formation of Fixed Capital
                                   451

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(%)
JO -
20-
10-

-



-
•- 	
	 ••~-~.
~"~~~-« 	 » Road
(7.1) (7.6)
' Sewerage

»- — — "^ ""*"" — — p^P-*=- -•-»• Dwellings
(3.3) (3.4) (4.2)
	 • Parks
•_ 	 -•-- "*~
Interim Kcono- hconomic and New liconomic New Economic liconomic New Sevcn-Year
mic Program Social Program and Social Pro- and Social Pro- Program for Economic Pro-
gram gram 1976 - 80 gram
(FY1964-68) (CY1967 - 71) (TY1970-75) (KY1973 - 77) (FY1976 - 80) (FY1979 - 85)
Investment Investment Investment Investment Investment Investment
¥ 17,800 bil. ¥ 27,500 Ml. ¥ 55,000 bil. ¥ 90,000 bil. ¥ 100,000 Ml. ¥ 240,000 MI.
Including Including Including Including Including Including
¥579,200 mil. ¥ 930,000 mil. ¥ 2,300 Ml. ¥5,650 bil. ¥7, 100 bil. ¥18,200 bil.
invested in sew- invested in sew- invested in sew- invested in sew- investeu in sew- invested in sew-
erage systems erage systems eragc systems crage systems erage systems eragc systems
(3.3%) (3.4%) (4.2%) (6.3%) (7.1%) (7.6%)
Fig.  5  Share for Sewerage  Systems  under Economic Program
                            452

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     Fig. 5 indicates the relations between the national economic pro-
gram and investment in sewerage systems.  Six national economic programs
have been formulated since 1964.  The share of sewerage systems in
investment increased each time a new economic program was worked out.
Of the total amount of ¥17,800 billion  ($80.9 billion), invested under
the interim economic program for 1964-68, sewerage projects shared 3.3%
or ¥579 billion  ($2.6 billion).  Under the existing seven-year New Eco-
nomic and Social Program (FY1979-85), which was formulated in 1979, a total
amount of ¥240,000 billion ($1,090 billion) is scheduled to be invested.
Of this amount, sewerage systems share 7.6% or ¥18,200 billion ($82.7
billion), indicating that the share has increased upwards of 2.3 times.
In Fig. 5, the rate of investment in sewerage systems is present in
relation to investment in other projects under the new economic program,
including roads, flood control, dwellings and parks. Aside from the amount
of investment in the construction of roads, which has a share of more
than 20%, the figures show that the amount of investment in sewerage
systems is higher than that of investment in other public works.
Investment in sewerage systems has increased,  because there is a rising
awareness among the people that sewerage is a basic facility indispens-
able for the development of the living environment and the prevention
of water pollution and because such investment is strongly supported by
the people.
     For the development of sewerage systems,  there have already  been
four five-year programs — the first (FY1963-66), second (FY1967-70),
third (FY1971-75) and fourth (FY1976-80).
                                   453

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(in thousand
billion yen)
8 ~

7 —

6 -
5 -
4 -
3 -


2 -
1 -



Program period


Period of exe-
cution
Accomplish-
ment rate

	 Amount planned
¥7,100 bil.
	 Actual amount





¥2,607.6 bil.


¥900 bil.
¥440 bil


¥296.3 bil.
First five-year program

(FY1963 -67)
(FY1963 - 66)

67.3%


~¥617.8 bil 1

Second five-year pro-
gram
(FY1967 - 71)
(FY1967 - 70)

68.6%


¥2,500 bil.





Third five-year program

(FY1971 -75)
(FY1971 - 75)

104.3%


¥6,843.7 bil.











Fourth five-year pro-
gram
(FY1976 - 80)
(FY1976 - 80)

96.7%

Fig. 6  Five-Year Sewerage Development Programs in the Past
        and Actual Records (excluding reserve funds)
                              454

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     Fig.  6 indicates the investment amounts  (planned and actual)  under
the four  five-year programs.   As  has been stated  earlier, the five-year
programs  are formulated in accordance with the national economic program.
The investment amount was roughly tripled each time  a five-year program
was replaced by a new one.  Fig.  7 illustrates the annual changes  in the
population for whom sewerage  systems are made available and in the
coverage  rate.  As of the end of  1980, the population for whom sewerage
systems were made available stood at 34.5 million and the coverage rate
reached about 30%.  In spite  of such systematic investment in sewerage
systems,  the targets have not been attained as scheduled because of the
reasons which have been introduced earlier.  Under the fourth five-year
program,  for example, the coverage rate was scheduled to reach 40% and
the population with sewerage  systems was expected to be about 45 million
by the end of fiscal 1980.
         9,616
  (in ten thousand
       persons)
 10,000 '
  8,000 -
  6,000 -
  4,000 -
  2,000 -
                9,827
                                 10,372
                             Vopu'
  ^foradmimst-*-
                                                  11,194
                                                                  11,706
'69  '70 '71  '72  '73 '74  '75  '76 '77  '78  '79  '80
         •63 '64  '65  '66  '67  '68 '69  '70
                                                                      - 10
                     Population for treatment   lnn
    (Note) Coverage rate =     f »j — 5 — . •. . .  .. — x 10°
             6      Population for administration
        Fig. 7  Changes  in Coverage Rate  of  Public Sewerage  Systems
                                    455

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1st Program (FY1963-66)
     The first program, which started in 1963, was formulated in accord-
ance with an interim economic program which was worked out to correct
the strains which had emerged from the policy to develop the Japanese
economy at a fast pace.  The high economic growth which had remained at
upwards of 10% a year boosted private investment and served to develop
the production .sector at a strikingly fast pace, thereby casting light
on the marked delay in public investment — particularly, in dwellings
and other livelihood facilities.  Here, sewerage systems were assigned
to serve as the core in the development of the livelihood infrastructure.
On the other hand, river pollution began at a rapid pace in this period.
But emphasis was put on raising the coverage rate (about 7% in those
years), which had remained far lower than that of advanced foreign
countries.  One reason is that there was not a full awareness of the
role of sewerage systems in the prevention of water pollution, and
another reason is that the administration for sewerage was dualistic.
In other words, the construction and management of sewage treatment
plants were placed under the responsibility of the Ministry of Health
and Welfare, whereas the Ministry of Construction took charge of sewers.
In those years, sewage treatment plants were primarily positioned as
facilities only for the improvement of the livelihood infrastructure from
the standpoint of public health and hygiene.  For this reason, invest-
ment was made by each municipality, and the mutual relations among
municipalities from the point of water pollution control were not taken
into serious account.

Second Program (1967-70)
     The scale of investment was enlarged for the second program, and
greater emphasis was put on the role of sewerage systems in the pre-
vention of water pollution than in the first program.  For this purpose,
the second program was defined as "working for an improvement of the
urban environment and contributing to the healthy development of cities
and public hygiene and the conservation of the water quality of water
bodies."  Under this program, a regional sewerage system, effective
                                  456

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 for  comprehensive water pollution control, was adopted for the first
 time.
     In  those years, measures against water pollution were formulated
 mostly with an across-the-board control over individual sources of
 pollutants or by the use of an effluent limitation standard.  But there
 emerged  a so-called stream limitation standard, according to which sewer-
 age  systems would be formulated with consideration given to the allow-
 able load of pollutants on the basis of the capacity of the water bodies.
 Sewerage systems under the second program, however, represented none
 other than the first step for the prevention of pollution.  The Sewerage
 Act  in those years was outdated in nature, as it emphasized the develop-
 ment of  the living environment.  The Act was not positioned for the
 prevention of pollution in sewerage.  Under the second program, the total
 investment amount was conspicuously insufficient, as some sewage plants
 could not be put into operation on schedule.  One thing worthy of
 special mention for Japan's sewerage administration was the fact that a
 revision of the laws made it possible for the Ministry of Construction
 to take charge of the construction, maintenance and control of total
 sewerage systems.

 Third Program (FY1971-75)
     In 1970 or the year before the start of the third program, the
 Sewerage Act was revised,  and this revision was epoch-making for the
 history of sewerage systems in Japan.  At the Diet session when the
 law was revised, known as the "Diet session against pollution," the
 deliberation on a number of bills concerning anti-pollution measures
was  conducted, and the bill for a revision of the Sewerage Act was
 submitted as one of the important bills to implement measures against
water pollution.  In the revision of the Sewerage Act, the conservation
of public water quality was incorporated as one of its purposes.
Against the pollution of public waters, the Government formulated
environmental standards for the water quality and environment in respect
to the major public water bodies,  and it was decided to attain these
targets within about five  years.
                                  457

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     A note-worthy concept was introduced in those years.  By this concept,
 sewerage systems were considered as part of a comprehensive water quality
 conservation project, a compatible program was formulated for each one of
 the waters bodies for which environmental standards had been worked out,
 and investment would be made in a systematic manner according to the pro-
 gram.  This concept was known as a stream limitation standard, according
 to which it was decided to develop sewerage systems in Japan.  Partly due
 to the establishment of one strict standard after another, it was in
 those years that many sewage treatment plants began to go as far as to
 incorporate in their future programs treatment at levels more advanced
 than secondary treatment.
     The third program called for an outlay of ¥2,600 billion ($11.8
 billion), as against an initially scheduled investment of ¥2,500 billion
 ($11.4 billion).  However, only about 50% of the projects incorporated
 in the program were accomplished, due to the outbreak of the oil crisis
 in 1973-74.  There was rising dissatisfaction among the people at the
 delay in construction of sewerage systems.  The fact that the accomplish-
 ment rate was so low was attributable to the following factors:
     1)  Rises in the unit cost of construction as brought about by inflation;
     2)  Rises in the cost necessary for safety measures for the con-
         struction of sewers;
     3)  Rises in the cost for an upgrading of plants so that their
         effluent may be made to meet standards;
     4)  Rises in the costs of additional facilities, such as for covers
         and anti-air pollution equipment, which were required as environ-
         mental or aethetic measures for sewage treatment plants.

 Fourth Program (FY1976-80)
     The fourth program was formulated in the midst of circumstances
where the role of sewerage systems was of increasingly greater impor-
 tance.  In the meantime, environmental water quality standards were worked
out for all major water bodies in Japan.  Under the Pollution Prevention
Program which was formulated for areas urgently in need of the accomplish-
ment of environmental standards,  the areas encompassed in this program
increased in number.
                                     458

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     On the other hand, the people's calls for the construction of sewer-
age systems came out in the form of "national minimums" for their living
environment.  Not only in the built-up areas where the development of
sewerage systems had been carried out, but also in mainstay rural com-
munities, there were strong calls for the development of sewerage sys-
tems .
     In other words, sewerage projects were made broader in coverage
from major cities so that they also include local cities.  The fourth
program envisioned a raising of the rate of diffusion in the population
from 22.8% at the end of fiscal 1975 to 40% by the end of 1980 with a
total investment amount of ¥7,100 billion ($32.3 billion).
     As in the case of the third program, many of the targets could not
be attained, though funds had been made available for practically every
project.  For one thing, this was because of a delay in the implementa-
tion of the third program.  Another reason is that as an attempt had
been made to develop sewers and plants at the same time, the rate at
which they were developed was thrown out of balance.
     As a result of systematic investment, however, it should be noted
that sewerage systems have accumulated and the pace of development will
become faster from now on.
     Progress of the development from 1963 may be summarized as follows:
     1)  Phase in which priority was given to the development of the
         national economy and the development of sewerage systems
         was not conducted to a full extent;
     2)  Phase in which the national economy developed at a constant
         pace and the development of sewerage systems was done from
         the standpoint of public health and hygiene;
     3)  Phase in which water pollution was in progress and the develop-
         ment of sewerage systems was taken into account for water
         pollution control;
     4)  Phase in which the development of sewerage systems was conducted
         with due consideration given to the prevention of pollution of
         major and other cities and their peripheries;
                                    459

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     5)  Phase in which the development of sewerage systems progressed
         so far as to encompass local cities and rural communities.

4.  FIFTH FIVE-YEAR SEWERAGE SYSTEM DEVELOPMENT PROGRAM
4.1  Background for the Program
     As has been mentioned earlier, the construction of sewerage systems
has been carried out at a level lower than what the people have hoped
for even with the four five-year programs in the past.  As there are
strong calls for sewerage systems,  their development is an urgent task.
On the other hand, measures for water pollution control have been
strengthened year by year.  The mass control of water quality was put
into effect in 1979, and effluent regulation in the three major metro-
politan areas of Tokyo, Osaka and Nagoya was strengthened to a great
extent.  As there was a delay in the construction of public sewerage
systems, criticisms were made that only private enterprises were assigned
with measures to prevent water pollution.  As there was progress in the
eutrophication of stagnant waters,  such as lakes and bays, calls emerged
for the implementation of measures against sewage treatment plants which
discharged wastewater into these waters.  To social calls for the saving
of energy and resources, the field of sewerage could not remain
indifferent, and there have been increasingly strong calls for the
construction of sewerage systems for which the cost and the consumption
of energy are low.  Now that there do not necessarily seem to be bright
prospects for the future of the Japanese economy, arguments have evolved
as to whether enormous amounts of money could be invested continuously
in sewerage systems as scheduled.
4.2  New Seven-Year Economic Program
     As has been explained earlier, investment has been systematically
made in sewerage systems in accordance with the national economic pro-
gram.  The fifth five-year program is based on the new economic program
formulated in 1979 for the period of fiscal 1979-85.
     The basic factors for the background of this program consist of the
necessity of harmonizing structural changes in the global economy and
the increasingly unstable supply and demand of resources, energy and
                                  460

-------
 food with  an  international economic  community which will deal with  these
 elements;  the necessity of a reasonable economic growth adaptable to
 changes  in the  structure of the Japanese economy, such as the transforma-
 tion of  economic growth; and the necessity of building a new welfare
 society  which will respond to a rapid increase in the number of elderly
 in  the population, dispersion of the population and industry and the
 increased  awareness of the people on the need to shift from a quantita-
 tive expansion  of their lives toward qualitative improvement.
     For the  management of the Japanese economy in future, basic policy
 under this program include (l)  correcting disparties in each economic
 sector,  (2) working for a conversion of the industrial structure and
 overcome limits on the availability of energy, and (5) striving to  realize
 a new welfare society unique to Japan.  For the economic management of
 Japan, the targets are to (I)  accomplish full employment and stabilize
 prices,  (g) stalilize and replenish the national life, (5) collaborate
 in and contribute to the development of the international economic
 community,  @  assure economic security and foster the infrastructure
 for economic development, (s)  reconstruct finance and come up with  new
 financial  responses.  For the accomplishment of these targets, it has
been decided to carry out a variety of measures in a harmonious way.
     For the stabilization and replenishment of national life, measures
will be  implemented for the development of social security, replenish-
ment of  education,  promotion of sciences and culture, replenishment of
consumers' lives, redevelopment of dwellings, conservation and develop-
ment of  the environment,  assurance of safety and replenishment of social
capital in order to assure a stable and serene national life, an affluent
and worthy-to-live  national life and a comfortable and tasteful national
life.   Particularly in respect to the replenishment of social capital,
the basic policy is outlined as follows:
     (1)   The level at which social capital is developed has been gradu-
          ally improved in recent years but is considerably lower than that
          of advanced nations.   Social capital service is relatively
          retarded,  compared to the desire for the replenishment of
          social consumption, which is growing in conjunction with
          improvements in the economic activity of the private sector
                                   461

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     and  in  the private consumption level.  It is necessary to
     further replenish social capital service.
     Public  investment plays an important function as part of a
     policy  for the control over total demand.  The development of
     social  capital with public investment is something which
     ought to be stepped up in a systematic and planned manner
     from a  long-range standpoint.  Though the financial situa-
     tion is rigid, roughly ¥240,000 billion  ($109 billion) of
     public  investment  (in terms of prices prevailing in fiscal
     1978 and including compensations for land acquisition) will
     be made during the program period in an  attempt to improve
     the  relative balance for the economic activity of the private
     sector  and replenish social capital service which will be
     required for the national life.  The stock of social capital
     (fixed  public net assets) is expected to increase almost twice
     by fiscal 1985.
(2)   In stepping up the development of social capital, there is a
     need to select and give priority to sectors of investment in
     order to contribute to a balanced development of the national
     land, while responding to the sophistication and diversifica-
     tion of the people's needs.
     During  the term of this program, priority will be given to
     investment in sectors which are directly tied in with  the
     national life in line with the concept of residence, etc.
     and  the development of social capital will be stepped  up in
     the  following manner.  In this case, however, keeping  the
     balance between types of social capital  and between social
     capital and economic activity will be taken into account.
     First,  in order to improve the environment for everyday life
     and  to  contribute  to a qualitative improvement of the  national
     life, an attempt will be made to work for a replenishment of
     the  facilities associated with the living environment.  The
     quality of dwellings will be improved and the development of
     facilities for which development has been delayed, such as
                             462

-------
          sewerage systems, solid waste treatment facilities,  urban
          parks, welfare facilities and cultural and educational facili-
          ties, will be stepped up.  In other sectors, moreover, priority
          will be given to the development of facilities closely tied
          in with national life, such as roads,  urban rapid transit
          systems, remote places, sea ports and airports of offshore
          islets, traffic safety facilities, urban rivers and rural
          environment facilities.
          Moreover, in order to check the concentration of population
          and industry in major cities and work toward balancing the
          use of the national land and promoting the countryside, the
          basic transport and communication facilities, national land
          conservation facilities and other facilities which will become
          the infrastructure for the above purposes will be streamlined.
          In order to reinforce the production infrastructure in rural
          communities, facilities for agriculture, forestry and fisheries
          will be streamlined.
     The program contains concrete targets for the promotion of social
capital development in this direction.  It is scheduled to invest ¥18,200
billion ($82.7 billion) in seven years from fiscal 1979 to fiscal 1985
with a view to bringing to about 55% the rate of  coverage for sewerage
systems to the total population
     Even in the national economic program, therefore, the development
of sewerage systems is considered insufficient and it has been agreed
to put greater emphasis on investment in sewerage systems.  The share of
sewerage projects in the total outlay has been increased by 0.5% from the
7.1% appropriated under the previous program (Table 2).  This is proof
that the importance of sewerage facilities and the urgency of their
development are recognized and high expectations are pinned on their
development in future.
                                    463

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               Table 2  New Seven-Year Economic Program
                                              (in hundred million yen)
>y Economic
\. program
Public ^~"^\^^
works ^^"--^^^
Roads
Dwellings
Sewerage systems
Urban parks
River conservation
Total
Grand amount
Economic Program
for 1976-80
Investment
195,000
65,000
71,000
15,400
55,000
401,400
1,000,000
Share (%)
19.5
6.5
7.1
1.5
5.5
40.1
100 (%)
New Seven- Year
Economic Program
(1979-85)
Investment
460,000
135,000
182,000
45,000
142,000
964,000
2,400,000
Share (%)
19.2
5.6
7.6
1.9
5.9
40.2
100(%)
4.3  Substance of the Program
     The fifth program which encompasses the five-year period of April
1981 to March 1985 contains the following targets.
     (l)   The development of sewerage systems in local cities will be
          encouraged to promote the concept of residence;
     (2)   The development of sewerage systems will  be encouraged to
          prevent the flood of built-up areas and enhance  the safety
          of the urban life;
     (D   To prevent the eutrophication of stagnant waters such as
          lakes, the installation of advanced wastewater treatment
          facilities will be promoted;
     (4)   The development of sewerage systems for rural communities will
          be encouraged;
     ©   Regional sludge disposal projects will be encouraged as well
          as projects of effluent reuse and resource recovery from sludge.
                                464

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a)  Scale of Investment and Targets of Development
     In the economic program above, the scale of investment was set at
¥18,200 billion  ($82.7 billion).  With the less bright prospects for
the future economic situation taken into account, it was decided to
extend this economic program for an additional 1.5 years or so and to
set the investment scale under the five-year program at ¥11,200 billion
($50.9 billion).  The major targets include the construction of about
12,000 km of sewers and that of sewage treatment plants and pumping
stations enough for another 11 million people.  In the sector of
regional sewerage systems, the major targets include, among others, the
development of 1,200 km of trunk sewers and that of sewage treatment
plants enough for about another 8 million people.  If the program is
accomplished as scheduled, about 54 million people out of a total
population of 123 million will be able to use public sewerage systems
and the coverage rate will be raised to 44% by the end of fiscal 1985.
The investment plans are shown in Table 3.
                                   465

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         Table 3  Project Cost for Fifth Five-Year Sewerage
                  Development Program
                                                   (million yen)
Classification
Public sewerage systems
Subsidized projects
Local independent projects
Regional sewerage systems
Subsidized projects
Local independent projects
Urban sewerage systems
Specified public sewerage
systems for industries
Subsidized projects
Local independent projects
Specified public sewerage systems
for conservation of the environment
Subsidized projects
Local independent projects
Coordination outlay
Reserve fund
Total
Total for subsidized projects
Total for local independent projects
New program
(FY 1981-85)
8,391,000
5,161,500
3,229,500
2,230,000
2,073,900
156,100
460,000
27,000
18,100
8,900
102,000
76,500
25,500
590,000
-
11,800,000
7,790,000
3,420,000
     Incidentally, the unit costs for the construction of sewerage
under this program are ¥550 thousand ($2,500) per person on the
national average.  Broken down, the cost includes ¥157 thousand  ($713)
per person for the construction of treatment plants, ¥393 thousand
($1790)  per person for sewers, and ¥27 million ($122 thousand) per
hectare for branch sewers.
                               466

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b)  Priority Matters
     Priority matters under the five-year program are as follows:
     a.  To promote the concept of residence incorporated in the Third
         Comprehensive National Development Program, the development
         of sewerage systems in local cities will be positively stepped
         up;
     b.  To prevent the flood of built-up areas, etc., and work for an
         improvement of the living environment, the development of
         sewerage systems will be promoted;
     c.  As part of housing and housing site policy, the development of
         sewerage systems in new urban areas will be stepped up on a
         priority basis;
     d.  To conserve water quality of lakes and other natural environ-
         ments and improve the living environment of rural communities,
         the development of sewerage systems will be stepped up;
     e.  To work for the accomplishment and maintenance of water quality
         and environmental standards, advanced treatment will be stepped
         up;
     f.  To establish stable disposal sites for sludge in metropolitan
         areas, regional disposal of sludge will be promoted.
     g.  Measures for energy saving, such as energy recovery from sludge,
         will be encouraged.
c)  Financial Plan
     The sewerage systems in Japan may roughly be classified into two
types — public sewerage systems and regional sewerage systems.
     The financial sources for the construction of sewerage systems
consist of, among others, national construction grants, local loans,
municipal funds, city planning taxes, prefectural grants and beneficial
assessments.  The composition of these financial sources is shown in
Fig. 8 in respect to public and regional sewerage systems.
                                  467

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         (1)  Public Sewerage
                 Sewers
           Subsi-   Self-
           dized    financed
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                                                                        Loan
                        City Planning Tax,
                        Beneficial Assessment,
                        Municipal Expenditure, etc.
          (2)  Regional Sewerage
  Sewers

Subsidized      Self-
       (90%)v ^financed
                   (10%)

                   - Loan
/
2
3
\

I/
4\
1 (
12
• . • ' '•.''.'.'
V •• National" • : •
1 • • Grant
• ... • .' ' ' . • t* • . .^
• •••

Loan
--__
^-^


^




•v
— -~
\
/
X
c
I
I

A
vTrT
UO
\
                                               Sewage Treatment Plant

                                                     Subsidized
                                                            (95%)-
/

3
4
,\
ID/
;:-;':--V:-:^-;V;^
. / .;National- ..-_2-'
'. • '. •, Grant •__ '3'."
• • . . ••
;v':o::v;.:-v>;v
Lo^n 4 ^


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/
/


J
                      Self-
1                      financed
                           (5%)

                        -Loan
                                                                      J_
                                                                      10
                                                                      10
                        Perfectural Expenditure,  etc.
Fig. 8  Composition of Financial Sources for Construction Cost in Sewage Works
                                      468

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a.  National Grants
    Now that sewerage systems must be developed as part of the
    policy of water pollution control from a national point of
    view, the rate of national subsidization of the cost of the
    construction of sewerage systems has been raised gradually.
    Since 1974, the rate has been set at 6/10 for public sewerage
    systems (2/3 for sewage treatment facilities) and 2/3 for
    regional sewerage systems (3/4 for sewage treatment facilities).
    Of a sewerage system construction project, the objects of
    national grants are confined to the main sewer, pumping
    facilities and treatment plants, and they are specified in
    a notice of the Ministry of Construction.  The rate of the
    construction cost of the facilities to be subsidized by the
    national government to the total construction cost is 60%
    (45% for designated cities and 75% for general cities) for
    public sewerage systems, and in the case of regional sewerage,
    this rate is 93% under the 4th Five-Year Program.
b.  Local Loans
    For a certain percentage of the construction cost, the floata-
    tion of loans or bonds is authorized, which constitutes a
    principal financial source for any construction project.
    By type of fund, sewerage project loans consists of government
    funds, financing corporation funds and private funds (publicly
    subscribed funds on the market and bank-related funds).  Of
    the amount planned for fiscal 1978, government funds accounted
    for 30%, public financing corporation funds 23% and private
    funds 47%, indicating there are signs that the rate of advan-
    tageous government funding is on the decline and that of
    costly private funds is rising.
c.  Beneficial Assessments
    Beneficial assessments for sewage works are imposed on the
    owners of land in the drainage area of public sewerage systems
    in accordance with a municipal ordinances and the City Planning
    Law.
                              469

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    Of the 700 cities for which public sewerage systems are approved,
    348 cities adopted this system in fiscal 1980.  The assessment
    per unit was ¥150-350/m3 in most cases.
    The beneficial assessments collected in fiscal 1980 accounted
    for about 1.0% of the cost for the construction throughout the
    nation and about 2.2% for cities which had collected assessments
    from beneficiaries.  Now that the financial situation of local
    autonomous entities is aggravated, there are calls for a re-
    inforcement of the beneficial assessment system and a raise in
    the rate of appropriation to the financial source for the con-
    struction.
d.  City Planning Taxes
    City planning taxes are levied by municipalities on the owners
    of tracts of land and buildings in city planning areas as object
    taxes to make up for the cost required for city planning projects.
    Therefore, the city planning tax revenue is appropriated for city
    planning projects other than the public sewerage system project.
    In fiscal 1979, the rate of city planning taxes in the cost of
    the construction of public sewerage systems throughout the
    nation was about 1.3%.
e.  Prefectural Grants
    ubsidies were extended by 12 prefectures (out of 47 prefectures
    throughout the nation) in fiscal 1979 to the municipalities
    engaged in a public sewerage project.  The share of prefectural
    government funds in the cost for the construction of public
    sewerage systems stood at 0.5%, and there had been signs of a
    drop in this share since 1974.
    As for the cost for the construction of regional sewerage sys-
    tems, it is made a fundamental rule for the prefectural govern-
    ment and the related municipalities to go fifty-fifty on the
    amount gained by deducting national grants from the total cost.
    The apportionment of the cost share among the related munici-
    palities is normally undertaken according to the planned waste-
                                 470

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water quantity ratio or the planned drainage area ration for each
municipality.
     In respect to the shares of the national and local autonomous enti-
ties in the financial source for the construction of sewerage systems in
fiscal 1981, a national government share of 39% of the total project
cost of about ¥1,800 billion ($8.18 billion) has been decided with the
local autonomous entities' share set at 61%.  Plans call for the
appropriation of about 93% of the local autonomous entities' share with
local loans.  The share for national grants was raised each time
a new five-year program was worked out, rising from 22% in 1967 to 39%
at present.  There have continuously been strong calls from local auto-
nomous entities to raise the national government's share.  In light of
the public nature of sewerage systems and the urgency of conserving
water quality, the share of the national grants has been on the upturn.
Now that the nation's financial situation has been aggravated, it is
presumably quite difficult to raise the rate further under the fifth
program.  Therefore, a financial plan will probably be formulated with
the present rate left as it is.  It has been suggested that the alloca-
tion of individuals' shares should be reviewed in a financial program
for sewerage projects to say the least for the reinforcement of the
beneficiaries' share.

5.  LONG-RANGE PROSPECTS FOR DEVELOPMENT OF SEWERAGE SYSTEMS
     The utlimate purpose of the development of sewerage systems is to
enable all of the people to use public sewerage systems, prevent built-
up areas from being flooded, prevent the pollution of rivers, lakes and
maritime regions and maintain water quality at levels which meet environ-
mental standards and, assure the availability of safe water for use and
dispose of generated sludge in a stable manner.  For this purpose, it
is necessary to construct operate and maintain sewerage systems in an
efficient and economical way.  The approaches to achieve the above
goals in a long-range perspective have been under discussion.
     The long-range prospects for the development of sewerage systems
in Japan in terms of 20 years in the future, as proposed by a national
study committee, are as follows:
                                   471

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(I)   Improvement of Sewerage Coverage Rate
     Sewerage systems will be completely developed in built-up areas,
whether they be in major or local cities, the development of the living
environment for major hamlets in rural communities in areas other than
the built-up districts will be stepped up, and the development of sewer-
age systems for the conservation of the water quality of lakes, etc.,
the natural environment of which is superior, will be promoted so that
the ratio of the covered population to the total population may brought
in live with the level of advanced Western nations by the year 2000.
     There are a number of views concerning the level of the coverage
rate which should be attained in Japan over the long run.  With the
concentration of population in urban areas now in progress, it is esti-
mated that urban population will account for 71.5% (96.5 million) of
the total population by the year 2000.  Nevertheless, it is a fact
that sizable population groups still continue living in rural communi-
ties.  No convincing conclusion is drawn as to whether a wastewater
treatment and disposal system as is available at present could be of
much effect in areas other than for cities.  At present, the target is
to make sewerage systems available for 100% of the urban population
and about 90% of the total population.  Incidentally, water supply,
including that which is supplied under a rural water supply system, is
supplied to about 90% of the total population, and sewerage systems
should be developed for hamlets with a population of up to 200.  In the
United States, the coverage rate stands at about 72% at present, and
it is understood that the question of the development of an on-site or
collection type for adoption by the remaining portion of the population
is under discussion.  In the case of Japan, the rate of development of
the collection type will presumably rise in light of the high popula-
tion density.  Be the matter what it may, it remains an urgent  task
come out with a method in which sewerage systems may be developed in
the countryside — particularly, in areas with a significantly  low
population density.
                                472

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 (2)   Upgrading Wastewater Treatment
      To  satisfy the water quality and environmental standards and pre-
 vent  a eutrophication of the stagnant waters, an attempt will be made
 to  reinforce measures for the minimization of pollutants at their gener-
  t
 ation sources.  In sewerage projects, too, advanced waste treatment will
 be  carried out in necessary areas to eliminate greater amounts of organ-
 ic  matter and nutrients.
      In  Japan, almost all rivers and other public waters are subjected
 to  strict environmental water quality standards.  It is the target and
 wish  of  the people to restore all waters throughout the nation to their
 beautiful condition and maintain them as such, and to make it possible
 to  use safe water.  When it is taken into account, however, that the
 flow  of  rivers near cities is decreasing due to an increase in the use
 of  water and that high self-purification capacity cannot be expected
 for rivers in Japan as their slopes are steep and they flow down quickly,
 it  is estimated that it will be necessary to have a considerable number
 of  sewage treatment plants for which some forms of advanced treatment
 will  be  required.
      The extremely high concentration of industry and population also
 is  a  reason for necessity of advanced 'waste treatment.  It is necessary
 to  make  a full study of the degree to which the people's consensus may
 be  gained on their share of the financial burden, which will increase
 in  conjunction with an introduction of sophisticated treatment tech-
 niques,  now that there are calls for an balancing of the outlay for
 sewerage systems for the whole economy and for energy saving and
 considering that the people, after all,  have to bear the maintenance
 and control costs of sewerage systems as taxpayers.  It is a fundamental
 rule at present for the users of sewerage systems to bear their opera-
 tion and maintenance costs,  but there is a need to study who will bear
 the additional costs incidental to an introduction of advanced waste
 treatment and how this will  be done.   At the same time, it is equally
necessary to develop less costly, energy-saving treatment techniques.
                                  473

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(3)   Improvement of Existing Facilities
     To maintain the functions of sewerage systems,  the improvement of
outdated facilities will be promoted and that for combined sewers will
be carried out, depending on the characteristics of  a given area.
     At present, the design of conduits and storm sewers for the dis-
posal of storm water is accomplished on the basis of the rainfall pro-
bability for 5-10 years, but the calculation of this probability is not
considered sufficient by any means.   In fact, the lowland sections of
many cities have flooded almost every year, and there is a need to ad-
vance the probability year which is  compatiable with the capacity of
rivers.  It is also necessary to devise non-structural measures, such as
for the underground permeation of stromwater.
     It is also a major task for Tokyo, Osaka and other large cities to
develop measures against overflows from combined sewers in wet weather.
The findings of many research works  indicate that the pollution load
of overflows cannot be ignored in terms of water pollution, and it is
desirable that appropriate measures  be worked out.  However, the cost
for improvement will presumably be tremendous, and measures are likely
to be formulated step by step, depending on the development of sewerage
systems.
(4)   Execution of Regional Disposal  System for Sewage Sludge
     For Japan whose national land area is limited,  the disposal of
wastewater and sludge is a very difficult issue.  To secure stable places
for disposal on a long-range basis,  elaborage surveys have been carried
out for agricultural and other effective uses, and these have been realized
in many districts.  In major metropolitan regions, where sludge is gener-
ated in significantly large amounts, it is considered difficult to make
use of the whole quantity and it has become an urgent task to devise a
system of regional disposal.  At present, surveys are under way to con-
struct reclaimed places for regional disposal in some parts of the bays
of Tokyo and Osaka.
                                   474

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 (5)  Reuse of Effluent
     It is known that the precipitation amount for Japan is great
 (1,800 mm/year) and Japan is relatively rich in water.  As a result of
 the concentration of population and industry in urban areas, it is esti-
 mated that the major metropolitan regions will become short of water ini
 near future.  Since that hopes cannot depend on the development of dams,
 it is an urgent task to establish a system for effluent recycling.

 6.  SUMMARY
     The present situation of sewerage system development, the situation
 of systematic investment in sewerage systems, the substance of the Fifth
 Five-Year Sewerage System Development Program and long-range prospects
 for the development of sewerage systems in Japan are summarized in this
 section.  As there was a delay for Japan's embarkation upon the develop-
 ment of sewerage systems, many difficulties have been encountered, but
 the development might be described as having made rapid progress thanks
 to systematically planned investment.  The focus for the development of
 sewerage systems also has been shifted from major cities to smaller
 cities and its emphasis from considerations of public health and hygiene
 to the prevention of water pollution.  There is apprehension about the
possibility of accomplishing the targets contained in the fifth five-year
program due to the aggravation of national finances, but there are many
 sewerage projects that have yet to be carried out.  Several other five-
year programs will be formulated in future in an attempt to attain the
 long-range development targets.
                                   475

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                                     Eighth  US Japan  Conference
                                               on
                                     Sewage  Treatment  Technology
    CURRENT ISSUES IN WATER POLLUTION
           CONTROL ADMINISTRATION
                     IN JAPAN
                    Oct.     1981
                   Washington, D.C.
The work described in this paper was not funded by the
U.S. Environmental Protection Agency.  The contents do
not necessarily reflect  the views of the Agency and no
official endorsement should be inferred.
           Toshiki Oshio
           Councilor for  Engineering Affairs
           Environment  Agency
           Government of  Japan
                       477

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1.   CURRENT STATE OF  POLLUTION  IN JAPANESE WATERS

     Although still very  far from a satisfactory  state,  an  overall  improve-
ment of water quality may be noted in Japanese  waters  in recent years.  Let
me start by examining the pollutants  for which  environmental water  quality
standards have been established under the  provisions of  the Basic Law  for
Environmental Pollution Control.   As  regards  toxic or  harmful  substances
relating to protection of human health such as  cadmium,  mercury and PCBs,
the ratio of samples exceeding the respective standards  to  the total number
of samples taken has continued to decline  over  the years.   (See Table  1.)
         Table 1.  Ratio of Samples Exceeding Water Quality Standards
                   Relating to Protection of Human Health To The  Total
                   Number of Samples Taken
Substances
Cadmium
Cyanide
Organic P
Lead
Cromium (VI )
Arsenic
Total Mercury
Alkylmercury
PCBs
Water Quality
Standards
0.01 ppm
N.D.
N.D.
0 . 1 ppm
0.05 ppm
0.05 ppm
0.0005 ppm*
N.D.
N.D.
1970
(%)
2.8
1.5
0.2
2.7
0.8
1.0
1.0
0
-
1975
(%)
0.31
0.02
0
0.32
0.02
0.24
0**
0
0.38
1979
(%)
0.13
0.01
0
0.00
0.01
0.16
0**
0
0.05
              (* Annual averages; **In number of sampling sites)
                                    478

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     Among a number of substances and items for which there exist water
quality standards relating to the preservation of our living environment,
taking BOD levels in rivers for example (See Table 2) , a general trend toward
improvement may again be noted here.  The non-compliance rate, however, is
high among small rivers and streams flowing through large urban districts.
The rate of achievement of environmental standards in 1979 was:  69% for
water bodies belonging to Category AA, 75% for Category A, 60% for Category
B, 46% for Category C, 56% for Category D, and 41% for Category E, with an
overall achievement rate of 65%.
             Table 2.  Ratio of Samples Exceeding Water Quality
                       Standard for BOD in Rivers
Water Quality
Categories
AA
A
B
C
D
E
Water Quality
Standard
for BOD
1 ppm
2 "
3 "
5 "
8 "
10 "
1971
36.7
30.9
35.6
39.9
52.8
70.2
1975
31.4
24.4
27.4
42.6
37.8
49.7
1979
23.9
21.5
28.1
43.4
36.5
43.5
(Number of
Water Bodies
1979)
(287}
(.1002)
(497)
(227)
(81)
(142)
     Taking for another example the number of coliform groups, one would get
a non-compliance rate of 79% for all water bodies in Category AA  (the stan-
dard is less than 50 MPN/100 ml), 73% for Category A (ditto, less than 1,000
MPN/100 ml), and 61% for Category B (.ditto, less than 5,000 MPN/100 ml)..
No improvement can be seen in this respect.

     Turning next to COD levels in coastal waters, a general trend for im-
provement may again be recognized, but the rate of achievement in 1979 was:
64% of water bodies in Category A, 82% in Category B, 99% in Category C, with
an overall achievement rate of 78%.  The rate was particularly low in the
"enclosed" or "semi-enclosed" bodies of water.  (See Table 31
                                      479

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         Table 3.  Ratio of Samples Exceeding Water Quality Standard
                   for COD in Coastal Waters to the Total Number of
                   Samples Taken
Water Quality
Categories
A
B
C
Water Quality
Standard
for COD
2 ppm
3 "
8 "
1971
38.5
30.5
1.5.2
1975
19.6
18.3
7.4
1979
17.4
17.1
4.7
(Number of
Water Bodies
1979)
(222)
(193)
(117)
     Looking at COD levels in lakes and reservoirs,  here again one may note

an overall trend for improvement, but the actual rate of achievement of
water quality standard is extremely low, as illustrated by the achievement
rates of 24% of water bodies in Cagetory AA, 56% in Category A, only 7% in
Category B, with an overall average rate of 42%.  (See Table 4)
                  Table 4.  Rate of Achievement of the COD
                            Standard for Lakes and Reservoirs
Water Quality
Categories
AA
A
B
C
Water Quality
Standard
for COD
1 ppm
3 "
5 "
8 "
1971
13.9
79.4
91.8
-
1975
62.0
69.4
84.6
40.7
1979
73.5
56.8
74.2
70.8
(Number of
Water Bodies
1979)
(21)
(62)
(14)
( 1)
                                     480

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2.   WATER POLLUTION IN  SEMI-ENCLOSED COASTAL  WATERS AND
     AN AREAWIDE POLLUTION LOAD CONTROL  SYSTEM
     In the three metropolitan regions of Tokyo Bay, Ise Bay and Seto Inland
Sea lives 53% of the total population of Japan, and 65% of manufactured goods
are produced by these regions.  As naturally to be expected, a large amount
of pollutants is discharged into these so-called "enclosed" water areas.
The flushing rate, or turnover of water with the outer fringes of the ocean,
is very small, and organic substances are easily retained and accumulate  in
thise water bodies.  Due to the great influx of nutrients, moreover, the
process of eutrophication is in rapid progress.  As a result, the water
pollution problem for these waters is getting worse and more complex every
year.

     In order to cope with this worsening progress of water pollution, the
84the session of the National Diet in 1978 enacted a Special Measures Law
for Seto Inland Sea Environmental Preservation and amendments to the Water
Pollution Control Law, both of which went into effect in June, 1979.  With
the objective of achieving and maintaining environmental water quality
standards, the new Law and the amendments of 1978 introduced a system of
measures aimed at an "areawide control of water pollution load", which sought
to cut down on the amount of total pollutant loadings into the three water
areas in an effective and integrated manner, from all sources including
domestic households and hydraulic load of rivers in upstream inland areas.

     Targeted reduction in COD load, according to the type of sources and
to each prefecture, goals for raising the percentage of sewered population,
basic guidelines on setting new effluent control standares, etc. were to  be
specified in a comprehensive Pollutant Reduction Plan.  The Plan was approved
by the Prime Minister in March, 1980, which set a deadline of 1984 for
reducing the COD loadings to the levels shown in Table 5.
                                    481

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          Table 5.   General Features  of  Tokyo Bay,  Ise Bay  and  Seto
                    Inland Sea regions and the Goals  for  Reduction
                    of COD Load

Surface Area of Water Body
(Km2)
Volume of Water
(X100 million m3)
Population (1976) (XI, 000)
Manufactured Goods (1976)
(trillion yen)
COD Loadings in 1984
(target) (tons/day)
Domestic Sources
Industrial Sources
Others
Tokyo Bay
1,400
540
22,200
32.2
660
386
180
94
Ise Bay
2,300
460
9,090
18.4
426
179
208
39
Seto Inland
Sea
23,000
7,330
28,130
44.5
1,283
517
666
100
     In this connection it is important to note that expanding sewerage
networks is an essential requirement for the achievement of these goals,
as indicated by the still very low rate of sewered population in these
regions:  in 1977, it was 39% in the Tokyo Bay region,  27% in the Ise Bay
region, and 31% in the Seto Inland Sea region.

     Along with reduction of COD loadings, inflow of nutrients must be con-
trolled so as to reduce production of organic materials by phyto-planktons
utilizing those nutrients.  In 1979, for example, 25% (700,000 tons) of all
fishery products in Japanese coastal waters was raised in the Seto Inland
Sea.  The number of "red tides" observed in the Sea, which was 48 in 1967,
jumped from 79 in 1970 to 320 in 1975 and 218 in 1980.   The red tides along
with them brought heavy damages to fishery production in the Seto Inland
Sea, and became an important issue to be urgently tackled with.
                                    482

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     In the face of this event, measures were taken under the Provisional
Law for Seto Inland Sea Environmental Preservation to reduce by 1976 the
COD loadings from industrial sources by more than one half of 1972 levels.
Thus, the average COD concentration in the whole Sea area in 1979 was
brought to 1.3 ppm, while its transparency (Secci depth)  was 6.4 meters,
Total N 0.26 ppm, Total P 0.026 ppm.  The overall rate of achievement of
water quality standards was 76% (49% for Category A, 80%  for Category B,
and 98% for Category C).  Compared with national averages, the achievement
rate of water bodies in Category A, which make up a major part of the Inland
Sea, is very low.

     Furthermore, daily inflow of phosphorous into the Seto Inland Sea
reaches as high as 81 tons per day.  (34 tons from domestic sources, 33
tons from inductrial sources, and 14 tons form other sources).

     In order to raise the water quality of the Seto Inland Sea, the Special
Measures Law for Seto Inland Sea Environmental Preservation provides for
measures to reduce the input of nutrients into the Sea area.  On the basis of
this Law, Director-General of the Environment Agency in July, 1979 directed
the governors of relevant prefectures to draw up plans, including specific
measures, to reduce or maintain the present level of P loadings into the
Sea by 1984, depending 'on the prevailing state of pollution by the nutrient.
Further studies will be conducted regarding possibilities for reduction of
P concentrations in Tokyo and Ise Bays.
                                     483

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3.   EUTROPHICATION OF  LAKES AND  RESERVOIRS

     Of the 98 lakes and reservoirs  for which water quality data are avail-
able, 54 show a pH of 8.5  or above,  and a DO of more than 10 ppm.  In these
lakes,  pH rises as CO2 is  taken  up by  the multiplying population of algae,
and DO  increases to the extent it becomes super-saturated.  Many of the lakes
and reservoirs have thus become  enriched with nutrients.  Lake Suwa, for
example, had a nitrogen concentration  of 0.26 ppm and phosphorous concentra-
tion of 0.02 ppm in 1931,  whereas the  corresponding figures rose to 1.59 ppm
and 0.63 ppm respectively  in 1979.
              Table 6.   COD Levels  in The  Major Lakes of Japan
                                   (in 1979)
Name of Lake
Tega-numa

Mikata-goko

L. Kitagata

S . Suwa

Kasumiga-ura

Hachiro-gata

L. Biwa

Water
Quality
Category
B
( 5 ppm )
B
( 5 ppm )
B
( 5 ppm )
A
( 3 ppm ) •
A
( 3 ppm )
A
( 3 ppm )
AA
( 1 ppm )
Maximum
Concentra-
tions
Observed
78 ppm

82

11

42

36

15

7.6 "

Daily Means
at Standard
Sampling Sites
(75% Values)
34 ppm

21

10

7.2 "

14

10

4.4 "

75% V/
W.Q.S.
Values
6.8

4.2

2.0

2.4

4.7

3.3

4.4

     It should also be noted that Japanese lakes,  many of which are  still  in
an oligotrophic state and have long been associated with one of the  greatest
transparencies in the world, are rapidly deteriorating in terms of their
clarity/transparency.  Secci depth of Lake Shikotsu, for example,  decreased
from 25 meters in 1925 to 18.7 meters in 1978, while in Lake Towada  it was
                                    484

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 reduced from 20.5  meters  in  1930 to a mere 9.8 meters in 1978.  The pheno-
 menon of lake eutrophication is not restricted to natural lakes, either.
 It now extends to  many of the man-made reservoirs constructed for drinking
 water purposes.  Of  a total  of 155 revervoirs surveyed in 1979, 55 is
 reported to  have suffered cases of fungus-like odor and taste in the water.
 In other cases, filters were clogged by mass populations of algae and
 filtering efficiency lowered.
4.   ENVIRONMENTAL  PRESERVATION OF  LAKES  AND  RESERVOIRS

     Water tends to stagnate long in closed water bodies such as lakes and
reservoirs making pollutants prone to accumulate.  Therefore, lakes and
reservoirs are apt to be polluted, in which it is very difficult to achieve
environmental quality- standards compared with rivers and the sea.   Moreover,
the progress of eutrophication often causes the excessive growth of aquatic
life, such as algae (fresh-water red tide, water bloom, etc.), giving rise
to serious obstacles to the water use, such as obstruction of filtering for
water supply, offensive oder and taste in drinking water, and damage-to
fishery.  Meanwhile, water polluting factors for lakes and reservoirs vary
largely, depending on the natural and social conditions of drainage basins.
Therefore, some of them cannot be fully coped with through the existing
measures based on the Water Pollution Control Law.  This being the case,  it
is essential to carry out new, special measures for the protection of the
water quality of lakes and reservoirs comprehensively and systematically
while making full use of the existing system for water pollution control.
It is also believed imperative to preserve the abundant waterside  environ-
ment of lakes and reservoirs.

     From the said point of view, the Director-General of the Environment
Agency asked the Central Council for Environmental Pollution Control on
Oct.  15, 1980 to submit a Recommendation on a Desirable-System for the
Environmental Protection of Lakes and Reservoirs.  On Jan.  27, 1981, the
council submitted the recommendations based on a study by its Subcommittee
on Water Quality.
                                    485

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      Salient points of the recommendation are as  follows:

      (1)   The Government should indicate a basic  idea for  the environmental
 protection of lakes and reservoirs,  and guidelines for protective measures.

      (2)   The prefectural governors  should map out environmental protection
 plans regarding lakes and reservoirs which are considered  to require the
 comprehensive and systematic measures of protection.  The  national and local
 public bodies should carry out the plans steadily and vigorously.

     (3)   Various measures for water  quality protection, such as establish-
ment of sewerage, should be taken steadily and elaborately  according to the
characteristics of lakes and reservoirs under long-term and comprehensive
plans so that the measures as a whole will achieve the desired results.
Such plans should include the strengthening of effluent control on factories
and other workshops, permission for establishment of specified facilities,
prevention of pollution caused by small-scale animal sheds, fish culture
grounds, domestic waste water, agricultural drainage, etc., and an introduc-
tion of areawide total pollutant load control.

     (4)  The environment of lakes and reservoirs represents a close combina-
tion of water quality and the natural environment of the neighborthood.
Therefore, positive measures should.be carried  out to preserve the natural
environment of the areas in the vicinity and at the same time, to ensure the
cleanliness and beauty of the water surface and waterside,  areas, and main-
tenance of open spaces.

     (5)  To protect the natural environment of lakes and reservoirs, various
existing systems should be fully utilized.  At the same time, attention should-
be paid to the functions of preserving water quality and serving as water
source, which are seen in the natural environment surrounding lakes and reser-
voirs.  In this context, study should be made, as necessary,  for the purpose
of establishing a new  system of designating areas in which certain types of
conduct would be controlled.
                                     486

-------
     (6)  The State should give maximum possible financial aid to local public
bodies, while both the State and local public bodies should strive to provide
workshop operators, etc. with assistance regarding financing and taxation.

     (7)  The Government should seek to establish a legal system for the
environmental protection of lakes and reservoirs in line with this recommenda-
tion as soon as possible.
                                      487

-------
                                         Eighth US/Japan Conference
                                                    on
                                        Sewage Treatment Technology
Regional Sludge Management Program in the Tokyo Bay Basin
                           October, 1981
                           Washington DC
      The work described in this paper was  not  funded by the
      U.S. Environmental Protection Agency.   The  contents do
      not necessarily reflect the views of  the  Agency and no
      official endorsement should be inferred.
          Dr. Takeshi Kubo

          President,

          Japan Sewage Works Agency
                                489

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1.  INTRODUCTION
     Tokyo Bay is a typical stagnant water body along with the Inland Sea
of Seto and Ise Bay from the view point of water pollution countermeasures.
(see Fig. 1).  It is long north to south with a length of about 80 km.
Its maximum width, east to west, is 30 km, the average width being 16 km.
The area of the water surface of the bay is about 1,400 km2 and the bay
holds 54 km  of water.  Its northern part is mainly sedimentary and the
water there is less than 40 m in depth but the southern part of the bay
contains a large undersea valley of several hundred meters in depth.  The
narrow-part of the entrance to the bay is only 6 km wide and this strait
prevents the exchange and movement of sea water, thus keeping a stagnant
state in the northern part of the bay.  The basin of Tokyo Bay extends
in the NW-SE direction across the bay and has an area of about 7,500 km2.
The four prefectures (Saitama, Chiba, Tokyo and Kanagawa) that form the
basin comprise 149 municipalities (86 cities, 45 towns and 18 villages).
Thus,this is a densely-populated area.  According to 1975 statistics, the
                        2
basin, with its 7,511 km , represented only 2% of the nation's total area
of 377,535 km2 but had 22.1 million people (19.7% of the national popula-
tion of 112 million).  Its industrial output amounted to ¥28 trillion
(or about US$ 127 billion, at 1US$=¥ 220), or 22% of the national total
of ¥127.4 trillion  (or about US$ 579 billion).  This means that pollution
sources are extremely concentrated there.  Under these circumstances, to
meet environmental water quality standards for Tokyo Bay sewage treatment
for the entire bay basin requires AWT, and sludge treatment and disposal
must be suitably planned.  The Ministry of Construction has, since 1979,
been studying creation of the most economical regional sewage management
program for the Tokyo Bay basin.  In fact, a presentation on this regional
sewage management program was made in the Seventh U.S.-Japanese Conference
on Sewage Treatment Technology.  This paper  mainly discusses a sludge
management program for the Tokyo Bay Basin.
                                  490

-------

-------
2.  ENVIRONMENTAL WATER QUALITY STANDARDS FOR TOKYO BAY AND ITS
    PRESENT STATE OF WATER QUALITY
     Environmental water quality standards have been set in accordance
with Article 9 of the Basic Law for Environmental Pollution Control and
the environmental water quality standards for coastal waters are categories
A, B and C (see Table 1) by the Environment Agency Notification.  The
powers to designate specific waters and their categories rest with the
National Government as far as important waters are concerned. Similar
powers for other waters are delegated to prefectural governors.   The
national government designation for Tokyo Bay is shown in Fig. 2.  This
bay is divided into 18 areas (two Category A areas, eight Category B
areas and eight Category C areas)  with 48 datum points where water
quality is measured at least once a month.  Fig. 3 chronologically
shows the extent to which the environmental water quality standards for
typical stagnant water bodies have been attained.  In Tokyo Bay, this
rate considerably improved from 44% in 1974 to 61% in 1979.  Table 2
shows the attainment rates in the different areas of Tokyo Bay.   In
1975, environmental water quality standards were met in all Category C
areas but not in the areas of Categories AandB. Whereas, in 1979 they
were met also in three of the eight Category B areas.  In the Category
A areas, the standards were not met but actually the CODMN values improved.
     In Tokyo  Bay,  which is in a stagnant water body, eutrophication
occurs due to the poor exchange of water and rich nutrients such as
phosphorus and nitrogen which are present.  Thus, government guidance
on phosporus control for this bay is being proposed.  Yet, the conduct
of phosphorus control will be a big problem, because phosphorus  is not
included in the water quality items of the current environmental water
quali ty s tandards.
                                  492

-------
                         Table 1.  Environmental Water Quality Standard Values for Coastal Waters
V Item
Cate-\
gory \
A
B
C
Standard values
Purpose of
utilization
Fishery class 1, bathing
and uses listed in B-C.
Fishery class 2, indus-
trial water and uses
listed in C.
Conservation of Environ-
ment
(pH)
7.8 - 8.3
7.8 - 8.3
7.0 - 8.3
Chemical
oxygen
demand
(CODm)
2 ppm or
less
3 ppm or
less
8 ppm or
less
Dissolved
oxygen
(DO)
7 . 5 ppm or
more
5 ppm or
more
2 ppm or
more
Number of
coliform
groups
1,000 MPN/
100 ml or
less


N-hexane
extracts
Not
detectable
Not
detectable

IO
CO

-------
                                                         Chiba
                                                         Prefecture
   Tokyo
   Metropolis
       Suraida River
         Tsurumi River
   Kanagawa
   Prefecture
          Yokohama City
                          (10).
                               (8)
    I      |	Category
               Category B
          I	Category C

               (1) -x- (17) refer  to Tokyo Bay (1) *• (17) while  (I) and
               (II) refer to Chiba Port (I)  and  (II).
Fig.  2   Environmental Water Quality Datum Points,  Tokyo Bay
                                   494

-------
90

80
                     Others
Inland Sea of Seto

     1974     '75      '76     '77      '78     '79 (Year)
  (Remarks)
  1.  Source:  Environment Agency
  2.  Rates of attainment were determined as follows:
        Number of areas meeting environmental
        	water quality standard	   in_ ..„,
        Number of areas covered by environmental
                 water quality standards
Fig. 3  Chronological Change in Rates of Attainment
        of Environmental Water Quality Standards
                             495

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      Table 2.   Table  on State  of  Attainment  of Environmental
                Water  Quality Standards  in Tokyo Bay  1974  -  1979
                (In terms of
Name of
Water Body
Chiba Port (I)
(ID
Tokyo Bay 1
2
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Category
C
B
C
C
C
C
C
C
C
B
B
B
B
B
B
B
A
A
Rate of attain-
ment of environ-
mental water
quality standard
1974
O
X
0
O
O
O
X
O
O
X
X
X
X
X
0
X
X
X
44%
1975
O
X
0
0
O
0
O
O
O
X
X
X
X
X
X
X
X
X
44%
1976
O
X
0
0
O
O
O
0
O
X
O
X
X
0
O
0
X
X
67%
1977
0
X
0
0
0
O
O
O
0
X
X
X
X
0
O
O
X
X
61%
1978
O
X
0
O
O
O
O
O
0
X
X
X
X
0
0
0
X
X
61%
1979
0
X
O
O
O
O
0
O
0
X
X
X
X
O
O
O
X
X
61%
0 indicates environmental water quality standards that were met and
X indicates those that were not met.
                                496

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3.  CURRENT SEWAGE TREATMENT IN THE TOKYO BAY BASIN
     The Ministry of Construction has conducted a need survey on local
governments concerned to determine the current state of sewage treatment
and its prospects.  According to the results of this need survey, the
current status of sewage treatment in the Tokyo Bay basin are shown in
Table 3, Fig. 4 and Table 4.
     As can be seen from Table 4, the 63 sewage treatment plants located
in the Tokyo Bay basin can be divided by treatment processes into 33
plants using conventional activated sludge, 21 plants using stepped
aeration, three plants using extended aeration, two plants using pure
oxygen activated sludge, two plants using high-rate aeration and two
plants using the high-rate trickling filter process most of these make
secondary treatment.  Some sewage treatment plants in Tokyo use the AWT
process, employing coagulation and sand filtration.
     Effluent standards of sewage treatment plants are set uniformly for
the entire nation by the Water Pollution Control Law.  But for waters
where the environmental water quality standards are difficult to attain
by employing the national uniform standards, prefectural governors may set
more stringent effluent standards than the national uniform standards.
In the case of Tokyo Bay, the prefectural governors concerned have
fixed more stringent standards which require BOD and SS to be 20 ^ 50 mg/Si
and 30 ^ 70 mg/£, respectively.  Effluents from three sewage treatment
plants exceeds the effluent standard in terms of BOD value.  This is
probably because one of these plants is overloaded even during dry
weather flow by 50%, while the other two are overloaded through combined
treatment with night soil.  As for SS, the standards in terms of SS value
are exceeded at one sewage treatment plant.
     The rate of industrial waste.water in the volume of sewage discharge
into sewage treatment plants differs from plant to plant, ranging from
0 to 50% of the treated sewage.
     Under the Sewerage Law, sewers must receive both domestic and
industrial wastewater.  Thus, it is mandatory for public sewers to
receive sanitary sewage from household and also industrial wastewater
from factories in the corresponding drainage area.  However, used water
not requiring treatment and other water unlikely to be improved by
                                   497

-------
sewage treatment such as cooling water and other non-polluted sewage
can be directly discharged into public water bodies even if these are
located in the drainage area.
     Further, the Sewerage Law controls industrial effluents by providing
pretreatment plants for more or less the same level of standards for
toxic substances contained  in industrial effluents as are set by the
Water Pollution Control Law (see Table 5).  For toxic substances con-
tained in sludge, there are quality standards set by a Prime Minister's
Office ordinance in accordance with the Waste Disposal and Public
Cleansing Law (see  Table  6).
     To guarantee the appropriate disposal of effluents, the Sewerage
Law provides not only for direct punishment, improvement order and
supervisory action against the violation of effluent standards listed
in Table 5 but also for reporting, inspection, etc. as preliminary
checks.  The sewage works managers conduct monitoring in accordance with
these provisions.
     As stated already in the section dealing with the attainment of
environmental water quality standards, the attainment of environmental
water quality standards in Tokyo Bay is unsatisfactory.  And in order
to improve water quality in large-scale stagnant water bodies such as
Tokyo Bay, an effluent mass control system became necessary; thus, the
Water Pollution Control Law was amended and the amended law was enacted,
effective in June 12, 1979.
     The effluent mass control system is designed to steadily improve
water quality by uniformly and effectively reducing the total pollution
load for heavily polluted large-scale stagnant water bodies.  Tokyo Bay,
Ise Bay and the Inland Sea of Seto were designated as three large scale
stagnant wate bodies.  With 1984 as the target year, reduction targets
by sources and by prefectures  in terms of pollution loads (COD^) were
set for waste water discharged into public waters in these designated
areas.  Table 7 shows COD^ loads to be reduced in Tokyo Bay by the
effluent mass control system.
                                  498

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                                   Table 3.  Current Status  of Sewage Treatment in  the Tokyo Bay Basin
10
Name of
prefecture
Saitama



Chiba



Tokyo



Kanagawa

Total



Number of
municipalities
38 cities.
30 towns and
16 villages
(84)
17 cities.
10 towns and
1 village
(28)
*27 cities.
S towns and
1 village
(33)
4 cities
(4)
86 cities,
45 towns and
18 villages
(149)
Prefectural
population
(in 1,000
persons)
5,060



3,519



11,357



4,224

24,160



Area
sewered
(ha)
8,312



6,735



48,826



11,707

75.580



Pupulation
sewered
(in 1,000
persons)
865



622



7,090



1,477

10,054



Rate
(%)
17



18



62



35

42



Amount
of sewage
treated
(in 1,000
m3/day)
401



257



4,501



933

6,092



Sludge production
(in terms of de-
watered cakes
moisture content
75%: 1,000 t/year)
100



59



1,084



141

1,384



Number of
treatment
plants
14



16



20



13

63



                          * The ward section of Tokyo was counted
                            75% was uniformly used for conversion
as one city.
as the moisture content for all dehydrated cakes.

-------
Legend
                                                                       Ibaraki Prefecture
        tt^.  Boundary of Tokyo Bay basin





        	  Prefectural boundary




            Location of treatment plant










         0     10      20     30 kn
   Fig.  4   Location of  Sewage Treatment Plants in Tokyo Bay Basin
                                      500

-------
cn
O
                      Table 4.  Current Status of Sewage Treatment Plant Operation in the Tokyo Bay Basin


              (1)  Saitama Prefecture
Name of local
municipality
Saitama
Prefecture
-
Kawagoe City
"
»
Kawaguchi City
Omiya City
Chichibu City
Gyoda City
Tokorozawa
City
Hanno City
Sayaraa City
Higashimatsuyama
City
Eakado
Tsurugashima
Total
Name of sewage
treatment plant
Arakawa
Furutonegawa
Takinoshita
Kasumigaseki
No.l
Kasumigaseki
No. 2
Ryoke
Omiya Nambu
duo
Gyoda
Tokorozawa
Hanno
Sayamadai
Ichinogawa
Kitasakado

Process of
treatment
Conventional
activated sludge
-
Stepped aeration
n
Extended aera-
tion
High-rate aera-
tion
-
High-rate trick-
ling filter
w
SteDDed aera-
tion
Conventional
activated sludge
"
"
••

Current
capacity
(mVday)
211,300
50,400
45,000
8,900
1,100
37,500
20,700
17,400
10,900
72,800
8,000
5,500
11,500
11,900
512,900
Dry weather
flow 1979
(m3/day)
187,100
19,900
39,700
5,100
900
33,500
24,000
18,400
7,400
34,200
5,700
4,800
8,400
12,000
401,100
Rate of
industrial
effluent
(*)
15.3
22.0
10.8
O
O
14.9
3.4
11.5
17.2
5.3
29.3
O
49.3
O

Quality of
crude sewage
BOD
(mg/«.)
103
119
158
138
136
121
212
90
89
206
183
248
157
151

SS
(mg/4)
115
184
104
116
127
131
84
49
96
157
173
176
124
153

Quality of
effluent
BOD
(mg/«)
11
5
16
9
12
17
40
48
17
12
10
13
6
15

SS
(rag/Jl)
9
4
13
6
9
16
26
28
20
8
24
8
3
12

Effluent
standard
(daily
average
value)
BOD20 mg/l
SS70 mg/8.
II
"
"
"
"
"
••
-
»
•
"
ft
-

Remarks
Refer Pig. 4
14
5
11
8
9
18
15
1
3
13
12
10
7
6


-------
               (2)   Chiba Prefecture
en
O
ro
Name of local
municipality
Chiba
Prefecture
Chiba City
«
-
(t
-
Ichikawa city
Funabashi City
Matsudo city
"
"
Kashiwa City
Yachiyo City
Narashino city
Ichihara City
»
Total
Name of sewage
treatment plant
Hanaoigawa
Chuo
Ogura
Sakatsuki
Omiya Hokubu
Omiya
Sugano
Nishiura
Kanegasaku
Kltakogane
Shinmatsudo
Toyoni
Katsutadai
Tsudanuma No. 2
Kikuma
Aobadai

Process of
treatment
Stepped aeration
Conventional
activated sludge
"
"
Extended aeration
Conventional
activated sludge
Stepped aeration
Conventional
activated sludge
Stepped aeration
Conventional
activated sludge
•
H
Stepped aeration
Conventional
activated sludge
-
Pure Oxygen ac-
tivated sludge

Current
capacity
(m'/day)
102,500
130,900
2,100
10,000
260
1,300
14,500
16 , 700
12,700
9,600
5,000
5,500
5,400
4,500
19,000
5,000
344,960
Dry weather
flow 1979
(m'/day)
70,400
102,800
2,500
7,700
200
1,300
13,000
11,000
11,000
7,600
4,600
4,800
5,200
3,900
9,200
1,600
256,800
Rate of
industrial
effluent
(%)
1.2
11.3
i
O
O
O
O
O
O
0
O
O
O
O
O
O
O

Quality of
crude sewage
BOD
(mg/t)
161
126
203
181
200
214
154
122
181
226
135
190
214
219
116
200

SS
(mg/JO
113
84
133
107
117
142
150
155
135
209
110
130
140
157
143
171

Quality of
effluent
BOO
(rng/l)
6
13
15
12
11
14
9
11
9
9
8
3
14
7
3
7

SS
(mg/J.)
3
11
9
5
10
8
13
4
12
14
6
8
18
8
4
11

Effluent
standard
(daily
average
value)
BOD20 rag/I
COD20 mg/£
SS70 mg/l
"
"
"
»
-
-
"
"
-
-
»
»
M
"
"

Remarks
30
31
32
33
34
35
26
28
24
22
23
21
27
29
36
37


-------
          (3)  Tokyo Metropolis
in
O
CO
NAM of local
Municipality
Tokyo Metropolis
"
•
Tokyo Metropolis
(ward section)
•
•
•
•
™
•
"
Machida city
"
Hitaka City
Hachioji City
"
Tachikawa city
Kino City
Hagashikuruae
Tanu City
Total
NaM of sewage
treatment plant
Kitatae* Mo. 1
Tavagawa Joryu
Mlnas4tas»
Shlbaura
Morigasaki
Shingashi
Ochiai
Odal
Kosuge
Mlkawashlaa
Sunasuchi
Tsurukawa
Hachida
Hitaka Tabu
Kitano
Mejirodal
Nlihikicho
Tamadaira
Shitaya
Sakuragaoka
Process of
treat»ent
Stepped aeration
•
Conventional
activated sludge
Stepped aeration
-
•
•
"
"
•
-
Conventional
activated sludge
-
Stepped aeration
•
"
"
Conventional
activated sludge
-
Extended aeration
Current
capacity
(•'/day)
136,000
75.000
S2.8OO
1.130.000
1,410.000
705,000
450,000
358,000
150.000
700,000
660.000
6,300
20,700
21,000
82,000
2,600
77,500
5,800
15,100
2,600
6,080,400
Dry weather
flow 1979
(•'/day)
70,600
15,300
16,100
861,000
991,000
290.000
580,000
290.000
73.000
647,000
494,000
5,000
11,300
12,500
56.0OO
4,100
42,000
4,500
13.000
2,400
4,500,800
Rate of
industrial
effluent
(%>
19.7
8.4
3.7
9.1
3.9
23.5
2.4
20.4
5.5
6.0
12.3
O
0
9.4
O
O
4.4
O
O
o
Quality of
crude aewage
BOO
<«g/D
142
101
243
165
129
121
162
113
107
148
189
190
150
186
200
200
253
213
175
111
SS
<«g/t>
119
72
182
137
132
101
172
97
63
122
139
240
145
210
220
200
127
252
159
156
Quality of
efjluent
BOO
(-9/t)
4
5
9
11
5
10
12
8
5
IS
11
8
8
28
14
14
17
IB
13
5
SE
(•g/O
3
4
4
8
2
6
12
6
4
8
8
9
6
38
26
26
16
11
5
7
Effluent
standard
average
value)
BOO20 mt/l
C0035 og/t
SS30 Bg/ 1
•
•
-
•
•
-
-
•
-
-
-
-
-
•
-
-
•


•eaarks
58
42
56
Includes WT
(coagulation
and sand
filtration) .
50
51
Includes
sand fil-
tration
facility.
44
45
46
49
47
48
61
63
59
53
52
57
54
*J
55

-------
                (4)  Kanagawa Prefecture
tn
o
Name of local
raun ic ipa 1 ity
Kawasaki City
-
N
Yokohama City
-
-
•
M
"
-
••
Yokosuka City
H
Total
Name of sewage
treatment plant
Iriezaki
Kase
Ikuta
Hokubu No. 1
Kohoku
Midori
Kanagawa
Chubu
Nambu
Kanazawa
Totsuka No. 2
Uemachi
Shitamachi

Process of
treatment
Conventional
activated
sludge
"
Pure oxygen
activated
sludge
Conventional
activated
sludge
"
"
"
-
"
H
-
-
••

Current
capacity
(mVday)
300,000
122,400
3,300
195,600
69 , 700
73,800
143,000
64,800
234,000
56,000
66,000
35,200
74,800
1,438,600
Dry weather
flow 1979
(mVday)
211,700
63,000
2,800
158,000
28,000
7,300
74,100
68,700
222,000
5,800
38,600
19,400
33,600
933,000
Rate of
industrial
effluent
<»)
48.7
31.1
0
10.1
3.7
0
3.4
3.9
4.1
20.5
15.8
2.2
5.5

Quality of
crude sewage
BOD
(mg/i)
108
60
229
140
78
360
95
140
160
160
220
136
107

SS
(rag/*)
90
57
135
130
74
450
120
100
130
160
190
113
115

Quality of
effluent
BOD
(mg/i)
10
8
12
10
9
6
6
11
13
4
11
14
14

SS

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         Table  5.   Pretreatment  Standards  (Sewerage Law)
       Toxic  substances
Permissible limits
  Remarks
Cadmium  and its  compounds

Cyanide  compounds

Organic  phosphorus  compounds

Lead  and its  compounds

Hexavalent chromium compounds

Arsenic  and its  compounds

Total mercury

Alkyl mercury compounds

P C B

Phenols

Copper

Zinc

Disolved  iron

Disolved  manganese

Chromium

Fluorine
0.1 mg/JJ, or less

1 mg/£ or less

1 mg/£ or less

1 n»g/£ or less

0.5 mg/Jl or less

0.5 mg/£ or less

0.005 mg/£ or less

Not detectable

0.003 mg/£ or less

5 mg/£ or less

3 mg/£ or less

5 mg/£ or less

10 mg/H or less

10 mg/H or less

2 mg/£ or less

15 mg/Si or less
More stringent
values may be
imposed by local
ordinances.
P H

BOD

S S

Normal hexane extracts

   Mineral oil

   Animal and vegetable fats
600 mg/d or less

600 mg/H or less



5 mg/£ or less

30 mg/H or less
Values out of
this range are
set by local
ordinances.
                                  505

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  Table 6.  Prime Minister's Office Ordinance under
            Waste Disposal and Public Cleansing Law
  Toxic substances
 Permissible
   limits
  Remarks
Arsenic

Cadmium

Mercury

Lead

Organic phosphorus

Hexavalent chromium

Cyanide

Alkyl mercury

P C B
1.5 mg/i

0.3 mg/£

0.005 mg/£

3 mg/£

1 mg/£

1.5 mg/£

1 mg/£

Not detectable

0.003 mg/Jl
Elution test
                           506

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                  Table 7  Total COD^ Load Reduction Targets for Tokyo Bay by the Effluent Mass
                           Control System Amount Regulation and Estimated Allowable COD^jj} Loads
                           Necessary to Meet Environmental Water Quality Standards (t/day)
tn
o
Name of prefecture
Saitama
Chiba
Tokyo
Kanagawa
Total for
Tokyo Bay
basin
1979
155
117
307
143
722
CODjflj reduction target
for Tokyo Bay 1984
141
112
280
127
660
Estimated allowable CODMN
load necessary to meet environ-
mental water quality standards
46
29
83
40
198
               Note:  The above estimated algal production amounts allowable loads are based on the
                      assumption that are 1/4 of their present level.

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     The recently determined total load reduction values are at levels
to which pollution loads can be practically reduced and seem unlikely
to allow environmental water quality standards for the entire Tokyo Bay
to be attained and maintained.  To attain the environmental water quality
standards, it will be necessary to raise the level of sewage treatment
further and, at the same time, carry out more stringent standards in
the future.

4.  PRESENT AND FUTURE OF SLUDGE MANAGEMENT IN THE TOKYO BAY BASIN
4.1  Sludge Treatment
     At present, sludge resulting from sewage treatment is generally
disposed of by the process shown in Fig. 5.  As shown in Table 8, 23 out
of the 63 sewage treatment plants in the Tokyo Bay basin practise sludge
digestion and 20 practise sludge incineration; together these plants
incinerated 700,000 tons (51%) out of the 1,380,000 tons (in terms of
sludge cakes with a moisture content of 75%) which were produced in
1979.
Thickening


Anaerobic
Digestion


Mechanical
Dewatering


Incineration
                  Fig. 5  Process of Sludge Treatment
                                  508

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   Table 8.   Number of Treatment Plants Provided with
             Digestion and Incineration and their Sludge
             Production in the Tokyo Bay Basin
Name of
prefecture
Saitama
Chiba
Tokyo
Kanagawa
Total
Division
Number of
treatment
plants
Sludge
produc-
tion
Number of
treatment
plants
Sludge
produc-
tion
Number of
treatment
plants
Sludge
produc-
tion
Number of
treatment
plants
Sludge
produc-
tion
Number of
treatment
plants
Sludge
produc-
tion
Digestion
Yes
8
26
6
22
6
598
3
62
23
708
No
6
74
10
37
14
486
10
79
40
676
Total
14
100
16
59
20
1,084
13
141
63
1,384
Incineration
Yes
5
81
2
16
9
522
4
84
20
703
No
9
19
14
43
11
562
9
57
43
681
Total
14
100
16
59
20
1,084
13
141
63
1,384
(Note)   Sludge production is in terms of dewatered cakes (moisture
        content:  75%)  in 1,000 ton/year.
                              509

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4.2  Sludge Disposal
     As shown in Table 9, most of the sludge produced at the sewage
treatment plants located in the Tokyo Bay basin is disposed of by land-
fill and reclamation from the sea.; 533,000 m3/year, or 71% of 751,000
mVyear which is the total amount of sludge disposed of by land-fill
and land reclamation was from downtown Tokyo and used for reclamation
from the seashore at the Central Breakwater.
     Sludge effectively used as a resource in its ultimate disposal by
recycling for greens and farmlands is, in many cases, land application
for parks and farmlands as compost.  In most land reclamation, dewatered
cakes and incineration ash produced at sewage treatment plants are used
as they are.
     In the case of Tokyo, where reclamation from the sea constitutes
most of reclamation, dewatered sludge cakes and incineraton ash produced
at its sewage treatment plants are used for reclamation from the sea.
In so doing, alumina cement is added at a rate of about 10% to the
dewatered cakes and incineration ash for the convenience of bulldozer
operation and is used for reclamation work and with adjustments so that
the compressive strength of soil after reclamation will be more than
0.5 kg/cm2.  Photo 1 shows a general view of the Chubo (Central Break-
water)  Mixing Plant of Tokyo.  Photo 2 shows sludge being shipped after
cement mixing and curing.
           Table 9  Methods of Sludge Disposal and Amounts
                    Disposed in the Tokyo Bay Basin (1979)
Method of
sludge disposal
Land reclamation
Reclamation from the sea
Land application to
greens and farmlands
Others
Total
Amount disposed
(1,000 ton/year)
128
623
10
21
782
Remarks
The moisture content
varies with disposal
method.
                                  510

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Photo 1   General View of Chubo (Central Breakwater)
          Mixing Plant, Tokyo
Photo 2   Shipment of Cement-Hardened and Cured Sludge
                          511

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4.3  Heavy Metal Content in Sludge
     Table 10 shows the heavy metal content in thickened sludge and
digested sludge for major sewage treatment plants in the Tokyo Bay basin.  In
the standard values for special fertilizers in accordance with a Ministry
of Agriculture and Forestry Notification.   As, Cd and mercury must be
less than 50 mg/kg, 5 mg/kg and 2 mg/kg,  respectively.  At sewage
treatment plants where the rate of industrial effluents in the crude
sewage is high, the permissible Cd limit is sometimes exceeded and in
some sewage treatment plants sludge cannot be used as a special fertil-
izer though this occurs only in apparently rate cases.  The heavy metal
content in sludge in Japan, as far as can be seen from the scant data
available, is smaller than in Europe and America.  However, farmers are
deeply concerned over the problem of heavy metals and countermeasures
against heavy metals handling is an important step toward the solution
of the sludge utilization problem.
4.4  Effective Utilization of Sludge as a Resource
     As stated above, the amount of sludge used for land application to
greens and farmlands in the Tokyo Bay basin is comparatively small.
This is probably because some farmers are very careful of the effect of
heavy metals in sewage sludge on greens and farmlands, because the effects
of heavy metals on soil are not certain and also compost facilities are
still at an experimental stage.  Moreover, sewage treatment plants in
the Tokyo Bay basin are far from areas where sludge can be applied as
compost for greens and farmlands.  Transportation costs are high.
     Compost facilities have recently begun to be installed at an
increasing number of sewage treatment plants.  At the Minamitama Sewage
Treatment Plant in Tokyo which treats sewage from a residential area,
a fully-automatic compost facility including four horizontal fermenting
tanks with a daily treating capacity of 10 m3 was installed in March
1980.  This sewage treatment plant produces a good quality of compost
with a moisture content of less than 40% by adding returned compost by
way of moisture adjustment to sludge having been dewatered to a moisture
content of 70% by a filter press and causing aerobic fermentation to this
mixture.  Characteristically, this plant does not use any other additional
                                    512

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                 Table 10.  Heavy Metal Content in  Sludge (in Dry Sludge  mg/kg) for Major Treatment Works
\v Sample
Heavy^^^
metals N.
Fe
Cu
Zn
T-Cr
Hg
Cd
Pb
As
A-l
25,020
639
1,676
158
1.2
1.6
67
5.4
B-l
5,810
157
1,100
28
1.5
ND
90
1.5
C-l
27,033
607
1,280
168
1.4
5.0
70
4.2
D-l
64,195
260
1,335
49
1.4
3.0
93
15.4
E-2
11,900
468
3,144
92
1.9
3.8
167
5.6
F-l
26,251
717
2,304
380
1.9
21.7
98
4.9
G-l
10,000
210
1,000
37
1.0
2.1
80
Un-
measured
G-2
Un-
measured
200
1,100
43
1.4
3.0
64
5.0
H-l
Un-
measured
507
2,935
139
3.2
4.0
168
8.0
1-1
Un-
measured
812
1,800
148
1.8
11.1
212
6.5
J-l
Un-
measured
149
1,065
20
1.5
1.4
55
4.2
en
>—»
Co
          (Note)  A, B, C ...  for samples  indicate different treatment plants and 1 and 2 are crude and digested sludge,

                  respectively.   Treatment plants A, F and I treat relatively large amounts of industrial effluents.

                  B, C, D, E,  G,  H,  and J  treat mainly domestic sewage.

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material or drying equipment for composting.  Compost produced is sold
for ¥250 (US$  1.13 )  a package (20 kg)  through the Tokyo Federation of
Agricultural Cooperative Associations.  Photo 3 shows the compost facility
of the Minamitama Sewage Treatment Plant.
     Also,  the sludge utilization as construction materials (e.g.,
concrete aggregate, roadbed material, brick, etc.) is being actively
studied, though this application has not yet become practical.
 Photo  3    Compost Facility at Minamitama Treatment Plant,  Tokyo
                                 514

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4.5  Forecasting of Sewage Sludge Production
     The production of sludge is increasing with the growing volume of
sewage to be treated.  Table 11 shows the results of need surveys on
sludge production by years and by prefectures.
     It is predicted that the rate of increase of sludge production will
be higher than the rate of increase of water consumption as the result
of sludge production increasing due to employment of the AWT process.
                     Table  11  Sludge Production
                                                 (Unit:  1,000  t/year)
^~--— ^ Year
Name of ^— -~^^^
prefecture ^^~^~-^^^
In terms
of amount
of
disposal
In terms
of
dewatered
cakes
Saitama
Chiba
Tokyo
Kanagawa
Total for the
Tokyo Bay basin
Saitama
Chiba
Tokyo
Kanagawa
Total for the
Tokyo Bay basin
1979
34
46
631
72
783
100
59
1,084
141
1,384
1985
93
73
1,020
68
1,254
321
140
2,060
271
2,792
1990
309
117
971
135
1,532
602
316
2,627
427
3,972
1995
719
180
1,462
210
2,571
1,047
552
4,040
572
6,211
2000
1,384
269
1,596
290
3,539
1,505
757
4,550
708
7,520
  (Note)  In terms of disposal amount, the moisture content varies by
         disposal methods.  In terms of dewatered cakes, the moisture
         content is 75%.
                                 515

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4.6  Avilable Life of Current Sludge Disposal Sites for Land-fill and
     Land Reclamation
     In view of the present state of sludge management,  the amount of
sludge that can be disposed of by current disposal sites is about
7,400,000 m3 — mostly by land-fill, land reclamation and reclamation
from the sea (see Table 12).   The available life of current sludge
disposal sites for land-fill and reclamation from the sea is less five
years in many cases.  This accounts for 69% of the total number of
local municipalities and for 96% of the amount of sludge that cannot
be disposed of in five years.
     The present rate of effective use of sludge in the Metropolitan
Tokyo area from viewpoint of sludge disposal is only about 1% and must
be increased by future efforts.
     Table 13 shows further details of periods relating to the remaining
five years.  In 15 local municipalities, the period is less than two
years.  Thus, it is extremely necessary to obtain more exact sludge
disposal sites as soon as possible.

     Table 12  Available Life of Current Sludge Disposal Sites for
               Landfill and Reclamation from the Sea and The Possible
               Amount of Sludge in The Tokyo Bay Basin
^\^^ Available
^\ life
^\.
Item ^\^
Number of local
municipalities
Amount of dis-
posal (1,000 m3)

less than
5 years

22
7,040

5-10


5
300

10-15


1
20

15-20


0
0

More than
20 years

0
0

Unknown


4
-

Total


32
7,360
     Table 13  Available Life of Current Sludge Disposal Sites
               where Disposal is Possible for Less than 5 Years
^\ Available
^\ life
^X.
Item ^\^
Number of local
municipalities

Less than
1 year

3

1-2


12

2-3


2

3-4


1

4-5


4

Total


22
                                   516

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4.7  Problems Raised by Local Municipalities
     At present, sludge is disposed of mostly by land-fill, land reclama-
tion and reclamation from the sea.  Local municipalities, finding it
difficult to obtain disposal sites in their own jurisdictions, now
often entrust sludge disposal to private enterprisers, in which case
it is mostly disposed of within or outside  of their own jurisdictions.
Further, as can be seen from Table 14, about 45% of all sewage treatment
plants in the Tokyo Bay basin have their sludge disposed of outside
their own jurisdictions.  Though the amount of sludge disposed represents
as much as 91% of the total volume of sludge disposed of by land-fill
and land reclamation from the seashore.  It is mostly disposed of by
reclamation.  More than a half of the amount of sludge disposed of by land
reclamation is disposed of outside its own jurisdiction.
     The distance from each sewage treatment plant to its disposal site
is indicated in Fig. 6.  With nine of the 49 treatment plants whose
distance to the disposal site is known, sludge must be transported for
more than 100 km (the maximum being about 250 km)  for disposal.  This
tendency is expected to increase in the future.
     One factor making sludge disposal difficult is the problem of the
content of such toxic substances as heavy metals.   So, to ensure exact
disposal, it is necessary to install efficient pretreatment facilities
for industrial effluents and strengthen the monitoring system.
                                  517

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    Table  14   Location of Disposal Sites and Disposal Amounts


                                                      (1979)
\. Disposal
Item \
Number of
treatment
plants
Disposal
amount
(1,000
m3/year)
Landfill
and land
reclama-
tion
Reclama-
tion from
the sea
Total
Landfill
and land
reclama-
tion
Reclama-
tion from
the sea
Total
Within own
jurisdiction
19
8
27
63
623
686
Outside own
jurisdiction
or boundary
22
0
22
65
0
65
Total
41
8
49
128
623
751
Remarks
Amounts used
for agricul-
ture , and
ocean disposal
are excluded.
The moisture
content of
sludge varies
'by disposal
methods .
c
rt
C
ill
e
M-l

O
01

,0
                   50        100


                        Distance (km)
150
200 or more
      Fig.  6  Distance  from Sewage Treatment Plant to Sludge

              Disposal  Sites in the Tokyo Bay Basin
                                518

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5.  NECESSITY OF THE REGIONAL SLUDGE MANAGEMENT PROGRAM
5.1  Increase of Sludge Volume and Difficulty of Conducting Land-fill
     and Land Reclamation
     As stated above, the available life of current sludge disposal sites
for land-fill in the Tokyo Bay basin is less than five years in 22 (67%)
of the 32 local municipalities, in the Tokyo Bay basin (including 15
local municipalities with less than two years) and sludge is now being
disposed of mostly by reclamation from the seashore.  As for land
reclamation, sludge from some sewage treatment plants has to be trans-
ported to disposal sites more than 100 km away for disposal.  Thus,
securing sludge disposal sites is now extremely difficult.
     Particularly, most land within 50 km of downtown Tokyo is used for
commerce, residence and industry at such a density that it is considered
impossible to locate the sites for sludge disposal within this 50-km
sphere in the future (see Fig. 7).  It is, therefore, basically neces-
sary to reduce sludge production and promoting sludge utilization as
a resource for agricultural and other purposes.  If there is no choice
but to dispose of sludge by land reclamation, sludge within the 50-km
sphere cannot but be disposed of by, say, reclamation from the sea rather
than by land-fill within this sphere because its disposal by land-
fill and land reclamation within its own jurisdiction is simply impos-
sible .
     For areas beyond the 50-km sphere, study must be made to plan the
joint disposal of sludge from two or three sewage treatment plants.
                                   519

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                  S////S///  Boundary  of Tokyo Bay basin




                  ^.___  Prefectural bounday




                     O    Major city
Fig.  7   50-km  Sphere  of Tokyo
                520

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 5.2  Possibilities of Utilization  of  Sludge  as  a  Resource  and  Reduction
      of Sludge Volume
      Local municipalities, which are  administrators of  sewage  works
 should do their best  in the management of  sludge.  They should not be
 merely concerned with sludge  disposal by land-fill and  land reclamation
 but they should, from a long-range point of  view, seek  also to actively
 develop the possibility of effective  utilization  of sludge in  the future
 for purposes  that  include its application  to greens and farmlands.
 Regarding the conversion of sludge into a  resource, study  is being made
 for its practical  and effective use  (see Table  15).  In fact,  sludge is
 already used  as compost for greens and farmlands, but the  amount of
 sludge thus used is only a fraction of sludge production.  To  increase
 its use for this purpose, its quality control must be complete; particu-
 larly,  it is  important to try to eliminate the  chance of toxic substances
 contained in  industrial effluents  from discharging into public sewers.
      As for the use of sludge as a construction material,  there are
 such potential  applications as the use of  sludge  for roadbed,  as a fill
 material and  the use  of sludge as  aggregates, broken stones, bricks,
 and blocks.   Related  techniques have  been  developed considerably but
 further study must be made particularly from the viewpoints of cost).
 quantitative  limitations and  distribution  that remain to be solved.
      In any case, sludge has  every possibility of being  used as a re-
 source  but, because of its cost which is still high, the prospect is
 that large  amounts of sludge will  not be used as a resource in the
 near future and can be  made available in only limited quantities.
     As  for the reduction of  sludge volume, many sewage  treatment plants
 are  trying  to reduce  the job of ultimate disposal by such methods as
 incineration because  of the difficulty of securing the necessary dis-
posal sites. Since, however,  incineration will require additional amounts
of oil  and other energy in view of the prospective increase of sludge
production.  It is hoped that a sludge incineration of an energy-saving
 type will be developed in the future.  Further, sludge incineration is
uneconomical as it requires additional equipment for deodorization and
air pollution control.
                                    521

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              Table 15  Possible Applications as Resources
Application
For greens and farmlands
For reclamation and land
fill
Roadbed and pavement
material
Aggregates
Bricks, etc.
Character
Compost, dry or dewatered cakes
Dewatered cakes, fermented stable
Incineration ash, fermented stable,
melted
Fired (incineration ash + shale, etc.)
Fired (incineration ash + clay or
silica sand)
5.3  Necessity of the Regional Sludge Management Program
     Regional measures are necessary because of the increase of sludge
production and the growing difficulty of treating and disposing of
sludge in its own jurisdiction by local municipalities.  This is charted
in Fig. 8.
5.4  Necessity of Reclamation from the Sea
     Sewage is collected in lowland by natural flow through sewers in
its drainage area, and sewage thus purified is returned to the natural
water circulation system.  In this connection, sewage treatment plants
are generally concentrated along rivers and bays.  The Tokyo Bay basin
is no exception.  In Chiba, Tokyo and Kanagawa Prefectures, which are
on Tokyo Bay, large sewage treatment plants are located in areas along
the Bay.  The 1995 sludge production in these bay-adjoining areas is
estimated in Table 16 from the results of a need survey as part of the
year's sludge production in the Tokyo Bay basin.  It represents about
2/3 of the amount of sludge requiring disposal.
     In the Tokyo Bay basin,  the land space is already used at such
densities for commerce, residence, industry and agriculture that it is
practically impossible to secure  sites suitable for sludge disposal.
Further, dependence on land reclamation from the seashore in Tokyo Bay
for the disposal of sludge is now inevitable for the following reasons:
                                 522

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                 Attainment  of Environmen-
                 tal  Water Quality Standard
              C
   Development of
     urban area
en
ro
to
Restriction of re-
sources and energy
                                  Increase of sludge
                                      production
   Limited land
   availability
   Limitation to
sludge reduction by
incineration, etc.
at each individual
  treatment plant
                              Limitation to disposal in
                              own administrative area
Regional sludge
Management project
Necessity of
efficient use
  of energy
                                                                             Promotion of
                                                                          conversion of sludge
                                                                             into resources
                                      Fig. 8  Necessity of Regional Sludge Management
                                              Program in the Tokyo Bay Basin

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 (I) Disposal sites can only be acquired at increasingly great distances,
    from the sewage treatment plants which means many future problems
    including those of transport cost and transportation system.
 (2) The bay-adjoining areas account for as much as 2/3 of the total
    sludge production in the Tokyo Bay basin.  This rate may reach 90%
    if inland sludge can be transported easily and economically by using
    mass transportation.
     But at sea, in Tokyo Bay too, the places left for land reclamation
are limited.  It is, therefore, important that local municipalities,
while trying to reduce sludge production on the one hand, should coop-
erate in using these disposal sites effectively and economically.
        Table 16  Sludge Production in Bay-Adjoining Areas in 1995
                  (in Terms of Disposal Amount) in Tokyo Bay

Dewatered cakes
Incineration ash
Total
Sludge production (1,000 m'/year)
Total amount
for the Tokyo
Bay basin
1,943
628
2,571
Total amount
for bay-ad-
joining areas
1,260
440
1,700
Rate of bay-
adjoining
area (%)
65
70
66
    Note:  The moisture content varies by form of disposal.
                                   524

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6.  RESEARCH AND TECHNOLOGY DEVELOPMENT FOR THE REGIONAL SLUDGE
    MANAGEMENT PROGRAM
6.1  Subjects of Study
     To realize regional sludge management in the Tokyo Bay basin,
study must be made on the following subjects:
(l) Coordination with Various Other Programs Concerning Tokyo Bay
    In materializing this program,  it must be thoroughly coordinated
    in the future with other programs including the reclamation plan
    for Tokyo Bay and the municipal solid waste  disposal program for
    Tokyo Bay.
(5) Conduct of Environmental Assessment
    The regional sludge management  program involves the possibilities
    of causing secondary pollution,  such as the effect of reclamation
    from the sea on the marine ecosystem and the problem of odors
    affecting local inhabitants,  as well as the effect on ship naviga-
    tion.   Careful scientific investigation, research and studies must
    be initiated in preparation for an assessment aimed to protect
    these  environments.
(5) Development of Energy-Saving  Technology
    A  tremendous amount of resources and energy is being consumed in
    sludge treatment and disposal.   In the future,  it will be necessary
    to try to develop resource- and  energy-saving technologies including
    the reduction of chemical consumption,  sludge incineration of the
    energy-saving type and the recovery of heat from digestion gas.
(4)  Long-range Outlook for Sludge Management
    Land-fill  and land reclamation have certain  limits in Tokyo Bay basin.
    Efforts  must be  made to realize  unlimited disposal of sludge  so  that
    sludge,  a product of human activity,  may be incorporated as much as
    possible  into the circulation of natural resources.   In the future,
    scientific investigation,  research and studies  into the possibilities
    of  such  unlimited disposal  as the  application to greens,  farmlands
    and the ocean must be initiated,  taking local conditions into con-
                                  525

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    sideration.  Application to greens and farmlands is already in
    practice but no comprehensive research or studies have been conducted
    on application to the ocean.  This is because application of sludge
    to the ocean is likely to be opposed in this country, a fishery
    nation where people are in the habit of eating considerable amount
    of fish daily.
    However, there is every likelihood that the application of sludge
    to the ocean, like its application to the land, can be incorporated
    into the circulation of natural resources by controlling its quality
    and the ocean environment, thereby contributing to the increase of
    marine resources.  Comprehensive research and studies, including the
    problem of food chains, are necessary in this connection.
(5) Study of Quantitative Reduction at Sources and Monitoring System
    for Quality Control of Sludge
    The per-capita amount of sewage and the resultant amount of sludge
    have increased yearly.  These must be reduced at their sources from
    the viewpoint  of resource and energy conservation.  It is also
    necessary to study an efficient monitoring system for the quality
    control of sludge.
6.2  Items of Technology Development
     Hereunder is a description of important considerations among items
of technical development and research including the program of joint
treatment and disposal of sludge in the Tokyo Bay basin:
6.2.1  Transportation System of Sludge
     Study will be made to see which means of transportation-pipeline,
truck, tank lorry or barge- is most suitable to transport dewatered
cakes, incineration ash yielded from the sewage treatment plant and
raw sludge taken from the settling tank to the sludge treatment and dis-
posal plant in each case.
     Specifically, the following items will be studies:
Q) Study on transportation of raw sludge
    (a) Study of the optimum moisture content of sludge transported by
       pipeline.
                                 526

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    ©  Study of the possible transportation distance by pumping.
    (g)  Study on pump blockages and countermeasures.
    ©  Study to prevent sludge from becoming anaerobic through long-
       distance transportation and to cope with the variation in solid
       concentrations.
    (e)  Study of the design and installation of buried submarine pipes.
 (2) Study transportation of dewatered cakes and incineration ash
    @  Study of sludge properties (including moisture content) in truck
       and barge transportation.
    (§)  Study of different types of barges.
 3  Establishment of optimum and cost-effective sludge transportation
6.2.2  Large-Scale Sludge Treatment and Disposal
     The flow diagram shown in the following chart can be conceived as
a regional sludge management program.
     Study will be made of the following items concerning the sludge
management program:
 (l) Study on treatment of sludge yielded from the AWT process
    Unlike sludge yielded from secondary treatment, sludge resulting
    from AWT is not easy for thickening and dewatering.  So, it is neces-
    sary to select an optimum combination of thickening (pressure
    flotation,  centrifuge)  and dewatering method (belt press, filter
    press, centrifuge)  for sludge from AWT.
 (2) Study of large-scale sludge digestion
    In  this work,  digestion is included as a process of the treatment of
    sludge by secondary treatment.  Since this large-scale plant will
    treat considerably more bulky sludge than a conventional sewage
    treatment plant,  it will be provided with a large digestion tank
    to  make efficient treatment possible.  Since few Japanese sewage
    treatment plants  have large digestion tanks at present, study will
    be  made of the structure and function of a large-scale digestion
    tank suitable  for the mass treatment of sludge.
                                     527

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in
ro
CO
(Secondary
treat
(AWT sludg*
(Dewatered
tion ash)
treatment sludge)
:ment plant
>) treatment plant 	 ••
cake and incinera-
treatment plant
Pipe
transportation
Pipe
transportation

Supernatant ...
treatment
t 1 t
,!. . t . n


-pMixing — -Land-fill
Reclamation
U-Compost'
                                 Fig. 9  Flow Chart of Regional Sludge Management Program

-------
 (D Study of cement mixing
    Though Tokyo has experience in the mixing of cement necessary for
    this purpose, study will be made of the proportion of cement used
    for this purpose and the determination of the mixing method most
    suitable for this work in strength and cost.
 (J) Study of volume reduction by field composting
    Since the dewatered cakes transported to disposal sites or those
    produced at sewage treatment plants must be reduced as much as
    possible, their volume may be reduced economically through field
    composting by aerobic fermentation.  In Japan, the conversion of
    sludge into compost by means of high-speed fermenting equipment
    has been studied and made practical because of the locations of
    sewage treatment plants and the size of their sites, but no field
    composting has yet been used.  So, study which includes demonstra-
    tion tests will be made of field composting.
 (D Energy-saving incineration
    Since incineration is most effective in reducing the volume of
    sludge, study will be made of an energy-saving incinerator of the
    self-sustaining combustion type that can incinerate sludge with
    low fuel consumption.
6.2.3  Large-Scale Land Reclamation
 Q Reclaiming methods
    Study will be made to see how best to use incineration ash, mixed
    sludge, compost and the remaining soil from construction works for
    reclamation.  The optimum reclaiming method will be studied
    particularly by testing soil conditions, deformation characteristics
    and coefficients of premeability, etc. by selecting separately the
    types of reclaiming materials, by testing the mix proportions of
    reclaiming materials and by studying the suitability of machines
    to be used.
                                   529

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(2) Treatment of leachate
    When land-fill is used for sludge  disposal,  highly polluted leachate
    may exude from the reclaiming materials.   The  properties  of the
    leachate exuding from sewage sludge,  will be predicted and, at the
    same time, study will be made of  an appropriate  treatment for this
    leachate.
6.2.4  Supernatant from the Sludge Treatment Process
     The supernatant from the digestion tank, the  thickner and the
dewatering facility are generally returned to the  sewage treatment plant
as return water to be treated.  Study will be made of a treatment plant
that can operate to purify upto the level of effluent standards as a
separate treatment of supernatant.
6.2.5  Electricity Generating System by Digestor  Gas
     This is a plan to carry out gas electricity  generation,  using
digestion gas, with the use of this electricity as the necessary
energy for treatment and disposal purposes.  Digestion gas electricity
generation has been seldom practised in the past,  though some cities
were equipped for this purpose in Japan.  At present, practical tests
are being conducted to realize the plan.  Study of a digestion gas
electricity generating system best suited to this project will be made
by referring the results of these tests.
6.2.6  Analysis of Cost-Effectiveness
     Comprehensive study will be made of the cost-effectiveness of each
individual project of sludge management and also for the regional sludge
management project.

7.  CONCLUSION
     The above is a brief description of the necessity of the  regional
approach for a sludge management program in view of the present quality
of water in Tokyo Bay, the present conditions of sludge treatment and
disposal and prospects for the future in the Tokyo Bay basin.  Further,
it outlines the numerous problems that must be studied to carry out
the regional sludge management program for the Tokyo Bay basin.
                                 530

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                                  Eighth US/JAPAN Conference
                                            on
                                  Sewage Treatment Technology
      STATUS AND OUTLOOK  OF  SLUDGE
 TREATMENT AND DISPOSAL  IN  KYOTO  CITY
                   October  ,  1981
                 Washington, D.C., USA
The work  described in this  paper was not funded by the
U.S. Environmental Protection Agency.  The contents do
not necessarily reflect the views of the Agency and no
official  endorsement should be  inferred.
                   Takashi Yoneda
                      Director,
                 Sewage Works Bureau,
                     City of Kyoto
                         531

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1.   PREFACE
     Kyoto  City  is an international cultural and sightseeing city located  in the
middle course of the Yodo River with a population of 1,460,000. The water of the
Yodo River,  into which municipal wastewater is discharged, is utilized as valuable
water resources  for approximately  11 million  people at  its lower reaches. Con-
sequently, the sewage works  of Kyoto City is absolutely  important not  only for
the improvement of the living environment but also for the preservation  of water
quality in the Yodo River.
     The construction  of  sewer systems in this city was  started  in 1930.  It was
suspended for some years during World War n, but it was resumed and is  progress-
ing.  At  present, the sewer network covers 48.8% of the urbanization areas and
60.2% of its total residents  as shown in Table 1 and Fig.  1. Together  with the
progress of sewer construction and more advanced treatment process, the treatment
and disposal of sewage sludge has grown a big problem.
     In this report, the history of sewage sludge  treatment and disposal in  Kyoto
is described and current problems and its countermeasures are also discussed.
                                                          (As of April*!)

                    Fig.  1   Sewer  District of  Kyoto  City
                                   532

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                       Table 1  Present Condition in Kyoto City
                      	(As of April, 1981)
                     Area of Kyoto City	 61,061 ha
                     Urbanization Area  	 14,906 ha
                     Population of Kyoto City ....  1,465,677
                     Sewer Service Area	7,275 ha
                     Coverage of Urbanization Area ....  48 & %
                     Sewer Served Population	881,860
                     Coverage of Population	60.2 %
                     Total Length of Pipelines	2,051210m
                     Treatment Capacity  .... 1,005,000m3 /day
2.   HISTORY  OF  SLUDGE  TREATMENT AND DISPOSAL
     In consideration of the social and natural conditions in the city, it is necessary
to select more effective process for sludge treatment and disposal. Kyoto is an inland
city  with an urbanization area of 14,906 ha and is surrounded by hills except for
the south where the Yodo River is flowing. In  the recent years, the urbanization
has spread to the suburbs on the foot of hills. As a result, it has become difficult
to obtain the site available for sludge disposal.
     Kyoto City has four wastewater treatment plants, Toba, Kisshoin, Fushimi and
Ishida  now in operation as shown in  Fig. 2. The history of sludge treatment and
disposal is represented by that  of the Toba plant. The Toba plant had a capacity of
78,000 m3/day  at the beginning  of operation in  1939. At present, its capacity has
increased  to 750,000 m3/day. This plant is  planned to treat 1,225,000 m3/day in
future  as the biggest plant of the city.
           1,000
            800
         ^
         c»
            600
            400
            200
Treatment Capacity in Present
 and Future (x 103 m3/day)
                                                                _T
                1965
                                1970
                                                1975
                                                                 1980
                 Fig. 2   Increase of  Wastewater Treatment
                                       533

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     The Toba plant is located at the site where the Kamo and Katsura rivers are
joined in the south of the city. About 40 years ago when the operation was started,
the plant was in the rural district. With the conditions of location and the economics
of maintenance and  operation taken into consideration, "anaerobic digestion—sun
drying—landfill" was first adopted as the process for sludge treatment and disposal.
It was evaluated  as  the best process from the results of operational studies at the
Kisshoin plant with a 7,800 m3/day capacity and the pilot tests of the mechanical
dewatering such as vacuum filtration.
     But the process of sludge treatment and disposal has been replaced with new
ones with the increasing quantities of influent  and sludge produced  that resulted
from  the  expansion of sewer network and treatment  capacity of the Toba  plant
as shown in Fig.3. First of all.it became impossible to treat sludge with sun drying,
and rotary-drum vacuum filter (filtration area: 47 m2/unit X  4 units) was installed
in 1965. Later, as the number of digestion tank and vacuum filter has increased to
deal with the increasing  quantity of sludge produced, the sludge dewatering has
become possible. While the quantity of dewatered cake was rather small, the landfill
                  u- c
                  If
                  >O
                        o t
o (L 5 J>
111!
            800
         o
         C  600
            400
            200
                  I      1
                                                 Annual Average
                                                 Influent Flow
                                                 (m3/day)
                                A.
                              / \ Dewatered Cake Produced (t/year)
                                         160 S
                                            £
                                         140 "0
                                            £
                                         120 H
                                            5
                                         100 "8

                                          80 I
                                                                  60
                                            •5
                                          40 >
                                                                  20
              1965
                              1970
                                              1975
                                                               1980
                      Fig.3   Treatment at The Toba Plant
                                      534

-------
disposal was carried  out in the yards of the Toba plant and others. In view of the
difficult situation to obtain the landfill site to cope with the growing quantity of
dewatered cake, it has become an  urgent problem to reduce the quantity of sludge
to be disposed of as much as possible.
     Consequently in 1968, the incineration of dewatered cake was started by multi-
ple hearth furnace (incineration capacity:  60 t/day unit  X  3  units).  Later, the
number of incinerator has increased, and since  1973,  the  whole dewatered  cake
has been incinerated. The raw. sludge dewatering has been adopted without digestion
process for the expanded facilities after the start of incineration although the sludge
treatment process was  "anaerobic  digestion—mechanical  dewatering" for the
existing facilities.
     In fiscal  1980, the whole dewatered  cake of about 450 t/day (moisture con-
tent; about 75%) including cakes from other treatment plants was incinerated.
Through the incineration, the amount of ash to be disposed of has been reduced to
about  one-seventh of dewatered cake  weight, but the disposal quantity still has
reached 63 t/day. Furthermore, the sludge quantity is  expected to increase more
and more  with the expansion of the sewage service area in the future. In the urban
environment where the urbanization is ongoing even in the suburbs, it is  impossible
to secure  the  landfill site  for the  vast  quantity of sludge produced. The saving of
resources  and energy has become the worldwide problem. The  urbanization of
districts near the treatment plant is progressing year by  year. From these changing
situation,  we  should evaluate again the process  of sludge treatment  and disposal
and replace with more effective facilities without pollution.
3.   CURRENT STATUS OF SLUDGE TREATMENT
3.1  SLUDGE TREATMENT PROCESS AT  EACH TREATMENT PLANT
     The outlines of the sludge treatment process at four treatment plants of Toba,
Kisshoin, Fushimi and Ishida are shown in Fig. 4. At the Toba plant, sludges pro-
Plant
Toba
Kisshoin
Fushimi
Ishida
Sludge Treatment Process
Sludge from
Kisshoin
Plant
1
Thickening
Tank

Night Soi
Collected
I
Anaerobic
p- Digestion
Tank
I
I
Digestion
Gas


-

Elutriation
Tank








Vacuum
Filter

De
Fu


/AfterDesulfurizedA
VUtilized for Fuel )



watered Cake from
himi Plant
i
Incinerator


Landfill



Sludge produced here is pumped to thickening tank at Toba Plant.
iThickening
(Tank

Thickening
Tank ~>

Vacuum
Filter

jMechanica
[dewatering

/Dewatered cake here is transported \
V to incinerator at Toba Plant . /
H

Drying j 	




_JPe!let-~l
jization <



/Dried sludge is \
/ transported to \
I adjacent municipal I
I wastes incinerator J
\ and burned with /
\refuse. /
         Note: Processes in dot line are in the midst of planning.
                     Fig. 4 Outline of Sludge Treatment Process
                                    535

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duced here and pumped from the Kisshoin plant, about 1.5 km away, are fed into
the thickening  tanks. A part of night soil  collected from unsewered area  is poured
into the digestion tank. There are two different sludge treatment processes. One is
"thickening—anaerobic  digestion—dewatering" and  the  other  "thickening—
dewatering." The dewatered cake is  incinerated, and ash is disposed of on land.
     Sludge produced at the Fushimi plant is treated in the "thickening—dewater-
ing" process, and the dewatered cake  is transported  by truck to the Toba plant for
incineration.
     The Ishida plant was put into operation in January 1981. As the amount of
influent is  small at present, sludge is  thickened and transported to the Toba plant
for subsequent treatment. But a  plan is under way  to incinerate sludge  produced
with municipal refuse at a solid waste incineration plant adjacent to the Ishida plant
following the treatment of the "dewatering—drying—pelletization."
3.2  STATUS OF SLUDGE TREATMENT
     The present status of sludge treatment at the Toba plant is briefly described.
The outlines of the main treatment facilities are shown in Table 2. The daily average
solids balance of the sludge treatment process in 1980 is shown in Fig. 5. The figure
shows that  the  quantities of  primary sludge and waste sludge are 41 t/day and
40  t/day respectively. It also indicates that the total quantity of solids produced is
81  t/day. Moreover, some solids  in side stream from the sludge treatment process
               Table 2 Outline of Sludge Treatment Facilities at Toba Plant
(1) Thickening Tanks
— — -^__
Type
Diameter
Water Depth at Wall
Number of Tanks
Capacity
I
Circular Tank
20.0m
3.0m
2
966m3
n
Square Tank
17.0mX 17.0m
3.6m
2
1,160m3
m
IV
Circular Tank
20.0m
3.0m
4
942m3
(2) Digestion Tanks (Two Stage Digestion)
- — — _____
Type
Diameter
Water Depth at Wall
Water Depth at Center
Heating System
Stirring System
Number of Primary
Digestion Tanks
Number of Secondary
Digestion Tanks
Capacity
Temperature
Detention Period
I
n
ffl
IV
Cylindrical tank with cone bottom and fixed cover
25.0m
5.2m
9.2m
25.0m
8.2m
ll.lm
Heat Exchanger
25.0m
8.2m
ll.lm
Steam Blowing
Gas Stirring
1
1
3,600m3
3,090m3
2
2

3
1
3
1
4,400 m3
30°C
30 Days
22.5 Days
                                      536

-------
 (3) Vacuum Filters
(4) Incinerators
" • — — 	
Type
Diameter of Drum
Length of Drum
Surface Area of Filter
Filtration Rate
Number Installed
I
Belt



n
Filter Type
3.5m
4.2 m
47 m2
17.5 kg dry
solid/m2 day
8
12
Type
Outside Diameter
Height
Burning Tempera-
ture
Number of Hearths
Capacity
Number Installed
Multiple Hearth Furnace
4.35m
10.04 m

5.10m
11.34m
6.78m
12.35m
800°C
8
60t Sludge
Cake/day
2
1
150t
Sludge
Cake/
day
3
are returned to the head of the wastewater treatment plant. Including these solids,
solids of 132  t/day are fed to  the thickening tanks. The quantity of sludge solids
pumped from the Kisshoin plant and fed into the thickening tanks is 9 t/day; the
quantity of night soil thrown  into the digestion tank is 7 t/day; and the quantity
of dewatered  cake solids  transported from the Fushimi plant  for incineration is
13 t/day. All these solids are treated at the Toba plant.
     In  the balance of sludge solids like this, 401 t/day cake is  produced at Toba.
A  total of 453 t/day  of dewatered cake (moisture content:  about 75%) including
52 t/day of dewatered cake from the Fushimi plant is incinerated into ash of 63
t/day. Part of ash is used  as specific fertilizers and  materials for the test of sludge
reclamation. All other ash is transported by truck to the site for landfill.
Cilu
DrySoUdi

401
103

Cifce
DcySoIldi
453
lib
Cake
DiySolldi
52
13

              Fig. 5 Sludge Flow at Toba Plant
                                            (Fiscal 1980, Dry Solids t/d)
                                       537

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4.   PROBLEMS ON SLUDGE TREATMENT AND DISPOSAL AND
     ITS COUNTERMEASURES
4.1  PROBLEMS ON SLUDGE THICKENING
4.1.1  EFFECTS ON TREATMENT EFFICIENCY
     The gravitational thickening has been conducted so far for combined sludge—
raw primary sludge (from primary sedimentation tank) and waste sludge. But recent-
ly, combined sludge  has tended to be thickened  poorly. As  shown in Fig. 6, the
solids content in thickened sludge was 4~6% in the past, but has decreased to 2~3%
in the recent years.  The deterioration of thickening properties has the following
adverse effects on the sludge treatment.
     In case that the  solids load is kept at the original design  level of the digestion
process, the quanitity of sludge fed increases, causing several troubles such as the
increase of heat required, the shortage of digestion period and the aggravation of
quality of supernatant. From the above reason, the quantity of sludge fed to the
digestion tank is controlled, so the operation efficiency of digestion tank is not so
good. Even if sludge is digested for about 30 days in such operational condition,
the solid content of digested sludge is only 3%, and some troubles occur in the
following dewatering process.
                   g
                     6
                               -•-<
                Fig. 6   Yearly Change of Solids Content and
                        VSS Content in  Thickened Sludge

     Sludge  is  first conditioned with ferric chloride and slaked  lime, and  then
dewatered with the rotary-drum vacuum filter. Figs. 7 and 8 show that the chemical
dosage increases with the decrease of solids content and that the filter yield sharply
decreases. Especially, as  the  digested sludge of low solids content produces hair
cracks on sludge cake which  reduce the vacuum pressure, it is difficult to dewater
such digested sludge. And the poor filter yield needs the extended operation time
which will cause the increasing cost  of electric power consumption and operation
personnel, and the expansion of facilities.
     The increase of moisture  and inorganic substances like slaked lime in dewatered
cake causes the increase  of the fuel consumption for incineration and the quantity
of ash, and the cost of incinerator operation and ultimate disposal are raised result-
antly.
                                   538

-------
J<

<3
Q

c

**


I
o
.•5
o

6
o
'C
V
"8
^
J?

-------
                                   30          40
                                  Sohds Content in Sludge (%)
           Fig. 8    Relation between  Solids Content and Filter Yield
4.1.2  RESEARCH  FOR  IMPROVEMENT OF SLUDGE THICKENING
       PROCESS
     The sludge thickening is essential to the sludge treatment. As described so far,
the deterioration of sludge thickening properties has adverse effects on the efficiency
of treatment process. So it is necessary to investigate  its cause and study counter-
measures for the improvement of thickening process.
     Fig. 6 shows that the  solids content of sludge is related to its VSS content in
the thickening process. The recent increase of VSS content is expected to have been
caused by the change of waste sludge properties and the increasing ratio  of waste
sludge to raw sludge  resultant from the change  of  influent substrates and the
improvement of sewage  treatment.  In  order to study the separate thickening  of
waste sludge and raw sludge, the  mechanical thickening of waste sludge  has been
researched.
     Pilot plant tests of mechanical thickening were conducted for three  different
thickeners—dissolved-air floatation, vertical centrifuge and horizontal centrifuge.
Based on the result of tests, the thickening performance, operation and economics
of three thickeners were comparatively evaluated. Then it was found that the dis-
solved-air floatation is the best for the thickening of waste sludge. (Refer to Fig. 9)
     However, the cost of construction and maintenance increases remarkably for
the mechanical thickening  as compared with the gravitational thickening. So it is
necessary to study the  economics of the whole  sludge treatment process—thicken-
ing, dewatering, incineration and disposal. It is  also needed to take account of the
scale  of facilities  and the relation of the existing facilities with new ones. For the
future expansion of facilities at the Toba plant (capacity:  475,000 m3/day), a
plan is  under way  to  thicken  separately waste sludge by dissolved-air floatation
process.
                                     540

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               Sludge Treatment Process for Expansion Plan at Toba Plant
  Raw
  Primary
  Sludge
 Waste
 Sludge
Gravitational
Thickening
(M


Floatation
Thickening
6

5
c
I 4
o
O
•8
o
to
3
2



	
--*L^
— ^.,
0
— —



Dewatering 	 J Incineration






""•• — . D
D^"""^
*~Vf?^ 	 •—


n Kisshoin
0 Toba
0 Fushimi


•^..^
— -^.







                                                               Landfill
                                                               or
                                                               Reclamation
                     0         100       200
                        Surface Solid Load (kg/m2 day)
                        (including Circulating Load)
300
                      Fig. 9 Thickening of Waste Sludge
                            by Dissolved Air Floation
4.2  ENERGY CONSUMPTION IN SLUDGE  TREATMENT
4.2.1   BREAKDOWN OF ENERGY  CONSUMPTION
     At the  sewage treatment  plant,  the  vast amount  of energy such as electric
power  and fuel is consumed. The energy consumption  at all the treatment plants
in Kyoto City by types of energy sources and by treatment processes are shown
in Table 3 and Fig.  10. These data show that nearly  150 billion kcal of energy
including electric  power, heavy oil  and digestion  gas is consumed to treat about
260  million  m3 of wastewater annually at  all the treatment plants of this city.
     As to the breakdown of consumed energy, electric  power accounts for 45.3%
and fuel for 54.7%. With regard to fuel, heavy oil covers about 67% and digestion
gas about 33%.
                                    541

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              Table 3 Energy Consumption at Wastewater Treatment Plants
                                                                   (Fiscal 1980)
~~ — — — ____^^ Treatment
- — — - ______^^ Process
Item ~~~~~~~-- — ______
Electric
Power
Heavy
Oil
Digestion
Gas
Municipal
Gas, etc.
Used Power
Calorie Equivalent
Used Volume
Calorie Equivalent
Used Volume
Carolie Equivalent
Used Volume
Carolie Equivalent
Total Calorie (X106 kcal)
(X103 kwh)
(X106 kcal)
(kE)
(X106 kcal)
(X103m3)
(X106 kcal)
f 	 i
(X106 kcal)

Pumping
10,163
8,740
229
2,061
0
0
—
0
10,801
Wastewater
Treatment
60,008
51,607
0
0
0
0
-
210
51,817
Sludge
Treatment
8,956
7,702
5,858
52,722
4,958
27,269
-
36
87,729
Total
79,127
68,049
6,087
54,783
4,958
27,269
-
246
150^47
 (Note)
 Conversion Factors:
Electric Power   IkWh = 860 kcal
Digestion Gas 1 m3 = 5,500 kcal
Propane Gas 1 kg = 12,000 kcal
      Heavy Oil 1 £ = 9,000 kcal
      Municipal Gas 1 m3 = 11,000 kcal
      Light Oil Kerosene 1C = 8,400 kcal
(1) By Energy
   Sources
        Municipal Gas and Others
(2) By Treatment
   Process
                                                            \— D.»at«nnn 1 8%
                                                                  	Thickening and
                                                                        Diflestion
     Fig. 10 Energy Consumption At Wastewater Treatment Plants (FY 1981)
     The energy consumption by the treatment process shows 7.2% for pumping,
34.5% for  wastewater treatment, and 58.3%  for sludge treatment. More than half
amount of consumed energy is spent for the sludge treatment. With respect to the
energy consumption in the sludge  treatment  process, the thickening and digestion
process accounts  for  23%, the  dewatering process for 3%  and  the incineration
process for 74%. The  energy  for sludge treatment  is supplied with electric power
by 9% and with fuel by 91%. Fuel for heating the digestion tank is only digestion
gas. The auxiliary fuels of incineration are heavy  oil and digestion gas which ac-
counts for 86% and' 14% respectively.
     Following the worldwide sharp rise of crude oil price,  the purchase  price of
fuel  and electric power has also risen remarkably from 1979 in particular, resulting
in the annual increase of the maintenance cost, most of which is the energy expense.
This trend  has a great effect on the finance  of sewage works.
                                      542

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 4.2.2  COUNTERMEASURES FOR  SAVING ENERGY
     Countermeasures for saving energy have been conducted at each plant as much
 as possible. At the sludge treatment facilities, digestion gas is used to save heavy oil
 for incinerator. For six  multiple hearth furnaces (incineration capacity: 630 t/day)
 at the Toba plant, heavy oil had been used formerly as auxiliary fuel. But, since the
 oil crisis in 1973, three of the six incinerators (60 t/day X 2 units; 150 t/day X 1
 unit) have been remodeled to use both the digestion gas and heavy oil. The reduc-
 tion of heavy oil consumption that has derived from the use of digestion gas is
 shown in Table 4. About 14% (950 kl) of fuel required for incinerator amounting
 to 6,800 kl turned on digestion gas (where digestion gas was converted into heavy
 oil equivalent), and the fuel cost was saved by 60 million yen in fiscal 1980.
                Table 4  Saving of Heavy Oil Used for Sludge Incineration
^""""-•^Fiscal Year
Item ^"~"-\^^
Cake Incinerated
(t/year)
Heavy Oil Used
(k£/year)
Digestion Gas Equiva-
lent to Heavy Oil
(kfi/year)
Total of Fuel Used
(as Heavy Oil)
(k£/year)
1976
139,707
4,460
694
(1,136)
5,154
1977
147,076
3,970
920
(1,505)
4,890
1978
149,106
5,105
991
(1,622)
6,096
1979
161,415
4,734
984
(1,611)
5,718
1980
165,374
5,858
948
0,552)
6306
(Note)
1. Conversion Factors Heavy Oil      18 = 9,000 kcal
                   Digestion Gas    1 m3 = 5,500 kcal
2. Figures in parentheses show used volume of digestion gas (X103 m3 /y)
4.3  ULTIMATE DISPOSAL OF SLUDGE
4.3.1  REGIONAL PLANNING  FOR SLUDGE DISPOSAL
     The procurement of ultimate disposal site for sewage sludge is in severe situa-
tion particularly because  of the  restrictions of inland city. Kyoto is  unable to
carry out the ocean dumping and the reclamation of sea surface as the ultimate
disposal method. With  the  history of over 1,000 years, there are  many cultural
relics and  scenic beauties to be preserved in this  city. So  the selection and procure-
ment of site available for landfill  is restricted. Accordingly, the  incineration of the
whole dewatered cake  has  been  enforced  both for the  sanitary disposal and for
reducing the  ultimate disposal quantity as much as  possible.  In the future, the
quantity of sludge produced is expected to keep increasing with the expansion of
the sewer service areas. Fig. 11  presents the amount of dewatered cake is likely
to reach about 800 t/day. In case of incinerating the whole cake, about  100 t/day
of ash (on dry solid basis) are estimated to be disposed of. It is impossible to secure
                                     543

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 in the municipal area  the disposal site where such  a large amount of wastes are
 landfilled.
     Many other large cities in Japan have such a problem. The ultimate disposal
 of the huge amount of sludge accompanied with the municipal activities is one of
 the important administrative problems.
     At present,  the Japanese Government has announced a plan for the construc-
 tion of regional ultimate disposal site. This plan is designed for local governments
 having difficulties in the appropriate disposal of wastes individually. The sphere
 of Tokyo Bay and that of Osaka  Bay are tentatively listed as proposed areas. Kyoto
 is included in the proposed area of Osaka Bay  sphere. The early enforcement of
 the plan for regional disposal site is expected to carry out the appropriate treatment
 and disposal of sewage sludge.
                Fig. 11   Estimate of Sludge produced in the future
4.3.2  SLUDGE RECLAMATION
     The ultimate disposal of sludge is the  biggest problem for this inland city as
described  above. If further efforts should be made to utilize  sludge as resources
besides landfill disposal, it will be greatly desirable from the view of saving recources
and energy. Therefore, a part of ash has been already utilized as soil conditioner for
agricultural land and soft ground in this city. For more reuse of ash and dewatered
cake, the following investigation is in progress.
     For the utilization of ash as roadbed material, the on-the-site  test has been
conducted, and good result has been gained  for the bearing strength of soil and like
that. The investigation is also ongoing on the use of ash to alternative material for
concrete product and  mortar grout. The research for composting  is under way
at the  Fushimi plant to apply dewatered cake to agricultural land as fertilizer. After
about  one-year  fundamental experiments, the small-scale composting device with
the horizontal gyle (cake fermenting capacity: 1 t/day) has been installed for the
production of compost. With the cooperation of those concerned with agriculture,
the survey  has been conducted on the effect of its application  to agricultural land
on growth rate  and soil condition. At the  same time, the market of composted
                                     544

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product  has  been investigated. The composition  of sludge compost is shown in
Table 5.  Further positive efforts should be made to utilize practically sewage sludge
as resources.
                      Table 5 Composition of Sludge Compost
Item (Unit)
Effective
Element as
Fertilizer
Regulated
Toxic
Substances
Leaching
Test of
Toxic
Substances
Nitrogen (%)
Phosphate (%)
Potassium (%)
Mercury (mg/kg)
Cadmium (mg/kg)
Arsenic (mg/kg)
Total Mercury (mg/C)
Alkyl Mercury (mg/C)
Cadmium (mg/8)
Lead (mg/S2)
Organic Phosphorus (mg/2)
Hexavalent Chromium (mg/fi)
Arsenic (mg/£)
Cyanide (mg/£)
Polychlorinated Biphenyl (mg/£)
Average in
Fiscal 1980
2.16
1.37
0.21
0.79
2.25
2.5
0.0025
ND
ND
ND
ND
ND
ND
ND
ND
Regulatory
Standards
-
-
-
2
5
50
0.005
ND
0.3
3
1
1.5
1.5
1
0.03
4.4  COUNTERMEASURES FOR POLLUTION  CONTROL
     On  treating and disposing  of sewage sludge, the necessary pollution control
measures  are  taken for districts  surrounding the treatment plants  and disposal
sites.  Concentration of  dust,  sulfuric  oxide,  nitrogen  oxide,  and  hydrogen
chloride  in  the  exhaust gas from incinerator are  regulated by the Air Pollution
Control Law and  the  Kyoto Prefectural Ordinance  for  Environmental Pollution
Control.  The cooling tower, sulfur removing and deodorizing tower, and electric
precipitator are installed to treat exhaust gas from incinerator as shown in Fig. 12.
Table 6 indicates that concentrations of  pollutants in exhaust gas are well within
the regualtion standards. The site for landfill disposal  of ash is subject  to the regula-
tions as  one of treatment facilities for industrial wastes. To prevent the seepage
from infiltrating underground,  retaining-walls of  reinforced concrete  made  are
built around the disposal site with  the bottom paved with asphalt. Then the disposal
site meets with the structure standards of ultimate disposal  facilities. Furthermore,
the leaching test of toxic  substances  is regularly conducted for landfill of ash in
accordance  with the Waste Disposal and  Public Cleansing Law. Table 7  shows the
result of leaching test is  far below the standards and there is no problem.
     On the other hand, the Fertilizer Regulation Law is applied to the utilization of
sewage sludge to green  field as  fertilizer. As indicated in Table 5, sludge compost
at the Fushimi plant fully  meets with the regulatory  standards as specific fertilizer
based on the law.
                                      545

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Incinerator


No 1"~No 6

H

0
T 	 T~
Scrubber
No
No
V
-
6
y




(F) Cooling Tower
Spr«y Type
lfit.3OOrn'/hr
76"C
4 1m0x 15mH
/2\ Sulfur R«mvo*l *nd
Spray Type
94,!00m'/br
40°C
3 8m# x ISmH
(3) Electric Doit Collector
Wet Vert.col "CottreH"
Type
80.000 mVhr
2 Units
7 1m x 6 Om x 14.85mH
(4) Stack
Reinforced Concrete M*de
>2Q,30Q«nJ/hr
2 Om* x 30mH
Fig. 12   Treatment Process  of Exhaust  Gas  from  Incinerators
           Table 6 Analysis of Exhaust Gas from Incinerator
Item
Dust
Sulfur Oxide
Nitrogen Oxide
Hydrogen Chloride
g/Nm3
ppm
ppm
ppm
Average in Fiscal 1980
Before
Treatment
0.182
96.9
65
36
After
Treatment
0.0263
(k=0.228)
2.41
62
18.6
Regulatory
Standards
0.7
k=3.5
300
700
               Table 7 Leaching Test of Toxic Substances
                         in Incineration Ash
                                                (mg/£)
Item
Total Mercury
Alkyl Mercury
Cadmium
Lead
Organic
Phosphorus
Hexavalent
Chromium
Arsenic
Cyanide
Polychlorinated
Biphenyl
Average in
Fiscal 1980
ND
ND
ND
ND
ND
0.11
0.00
ND
ND
Regulatory
Standards
0.005
ND
0.3
3
1
1.5
1.5
1
0.03
                                546

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5.   CONCLUSION
     In Kyoto City, the sewerage construction is now progressing based on the new
five-year plan (1981-1985) corresponding to the 5th five-year sewerage construc-
tion plan of the Japanese Government. It will be necessary to conduct the advanced
wastewater treatment as a city located at the upper reaches of the  Yodo River and
the Seto Inland Sea. As  a  result,  the treatment  and disposal of ever-increasing
sewage sludge is a crucial problem on sewage works in this city.
     It is clarified that the conventional concept of disposing of ash on land is not
enough to  cope with ever-increasing sewage sludge. It is necessary to promote the
utilization of sewage  sludge as resources by means of positive researches and tech-
nology developments. Accordingly, the new proper system for treatment, disposal
and utilization of sludge should be established in consideration of current situation
of Kyoto and  also from  the standpoint  of energy saving and pollution control.
But, for the resolution of  the problems on treatment and disposal of sewage sludge,
it is necessary to gather not only the sewerage technology  but also the extensive
fields of knowledge.  Furthermore,  the cooperation of various  fields and regional
administrative policies are also indispensable.
                                      547

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                                            Eighth US/Japan Conference
                                                       on
                                            Sewage Treatment Technology
COLLECTIVE PRETREATMENT OF  INDUSTRIAL  WASTEWATER
                 FROM  MINOR  ENTERPRISES
                        IN YOKOHAMA
                         October    1981
                         Washington D.C
     The work described In this paper was  not funded by the
     U.S. .Environmental Protection Agency.  The contents do
     not necessarily  reflect the views of  the Agency and no
     official endorsement should be inferred.
                      Shigeki Miyakoshi
                      Senior Technical Advisor
                      Sewage Works Bureau
                      City of Yokohama
                               549

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INTRODUCTION:
     Yokohama has developed as an international trading city, an industrial city, and
also  a residential city. But, on the other hand, in the rapid urbanization, many pro-
blems have  appeared  such as the  pollution of public waters, air pollution, and a
marked  reduction in green tracts of land, etc. For taking measures to cope with the
situation, the demand of the citizens  for strengthening of the regulations concerning
industrial wastewater as well as for the planning and rapid construction of sewerage
systems has grown.
     Major enterprises which have large scale management resources and a high level
of technological ability  can implement measures to cope with industrial wastewater
with relative ease. It is often, however, difficult for minor enterprises to take appro-
priate measures to cope  with industrial wastewater because of their inferior economi-
cal and  technological ability and their narrow sites. Therefore, when seeking an over-
all means to cope with industrial wastewater, the problem of minor enterprises is
an important problem in need of a quick solution.
     Yokohama city has planned to develop reclaimed land in coastal areas in order
to remove factories  scattered in the city to the land based on the plot of city redeve-
lopment, aiming for improvement  of the urban  environment, and the  recovery of
urban functions,  and  further, to solve  effectively the problems of environmental
pollution such as industrial wastewater and noise, etc. as well as to advance the indus-
trial modernization of the removed enterprises.
     The collective pretreatment at Kanazawa of industrial wastewater in this report
has been considered from the  aspect  of measures to cope with the industrial waste-
water of minor enterprises.
     In  the following, the  background and process of the reclamation undertaking at
Kanazawa, and the planning, design  and bearing  of the expenses of the collective
pretreatment of industrial wastewater will be stated.

1.   Urban Renewal Strategy in Yokohama
     Construction of  the  city of Yokohama originated in  the conclusion of "the
Treaty of Friendship between Japan and U.S.A." in 1858 by which Japan opened her
gates to the  world after  the isolation of over three hundred years, and took her first
step  tow'ard  modernization. As the trade with other countries progressed after the
opening of Yokohama harbour, commercial activities prosphered in Yokohama, and
it displayed all the atmosphere and color of a harbour city.
     After that, Yokohama reclaimed tracts from the sea, and on the coastal reclaim-
ed land, the iron industry, ship-building industry and further heavy and chemical
industries centered on petrochemical industries have developed. Subsequently, a huge
industrialized zone of Tokyo and Yokohama  districts  has been formed on a coastal
strip of Tokyo  Bay which  connects  Tokyo, Kawasaki,  and Yokohama. Thus,
Yokohama has had an additional character as an industrial city.
     Further, the increased population in the Metropolis of Tokyo which resulted
from Japan's high economical growth starting from the 1960s was  faced by a rise in
the price of  land to move  outside of Tokyo, so that there has occurred an extraordi-
nary phenomenon of  a marked population growth of Yokohama by about  100,000
                                    550

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 per  year mainly in its  inland districts, which  cannot be seen in other cities. Thus,
 Yokohama  has  had a character of a residential city as a dormitory town of Tokyo.
 Yokohama  has now become the second city of Japan and has a population of about
 2,800,000.
     With such  a background the urbanization of Yokohama has proceeded rapidly
 and  disorderly.  Consequently, various urban problems  resulting from overcrowded
 cities have occurred.  The environmental planning, and public utility investments for
 intensifying urban  functions could not keep pace with the urban problems, this sit-
 uation has resulted in the worst form of environment such as the mixing of residences
 and  factories, a  marked reduction in green tracts of land, flood damage, pollution of
 public waters, and air pollution, etc.
     Measures to cope with such problems have two aspects, one of which is to direct
 and  regulate rapid developments and industrial activities, and the other is to plan the
 arrangement of  fundamental urban facilities. In Yokohama, rapid developments and
 industrial activities have been directed and regulated by the method  of agreements
 with housing  site developers and industrial enterprises, respectively.  On the other
 hand, six fundamental projects for making the physique of the city by highly utiliz-
 ing urban spaces, and the proper arrangement of various urban facilities have been
 determined. Through the  execution of these measures, Yokohama is putting forward
 the  construction of "Yokohama  city where citizens can live a safe and comfortable
 life".
     The six main projects, which are centered on the undertaking for strengthening
 the  central  part, and  are  connected with each other as shown in Fig. 1,  will
 change the basic urban structure of Yokohama, and  also play the role of tractor for
 undertakings of  high citizen demand such as the planning of roads and sewerage  sys-
tems, the construction of schools, residences, and parks, and defense against environ-
mental pollution and disasters which are not  included in the six main projects.
                 c
     Sprawl
                 C
                   Becoming a dormitory
                   town of Tokyo Metropolis
                    Worsened environment
                    Lowered functions
Mixed existense
of residenses and factories

c
i
Traffic ^U—
congestion J^



          Rg. 1   Schematic Diagram of the Conception of the Six Main Projects
                                       551

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         KANAZAWA'fij
                       r..'.:i Reclaimed land
                       k'.*J Planning for reclamation
          Fig. 2  Illustration of coastal lines
2.   A Land Reclamation Project at Kanazawa
     The land reclamation project  at Kanazawa is being executed as one of the above
six major projects.

2.1   The aim and outline of the project
     Yokohama has developed by reclaiming
tracts of land from the sea and constructing a
harbour  and  factories.  However, coast  of
Kanazawa  was the final natural coastal line
left  to  Yokohama  as  shown  in Fig.  2.
Therefore, the reclaimed land is  to be con-
sidered to be utilized for all the  citizens  of
Yokohama. The aim of the project is to pro-
vide factory sites having a  business environ-
ment  which  is  adventageous in  location
conditions, and to remove improperly located
factories which are scattered in the residen-
tial  areas  as shown  in  Fig.  3 to suitable
sites. Further the  project  also  aims  for the
utilization of  the old  sites1 of
removed factories for urban faci-
lities such as road facilities, parks
and  green tracts of land, plazas
for refuge, etc., shopping centers,
and office streets, etc. to advance
the  redevelopment of the  city,
and, at the same time, the const-
ruction of an  urban industrial
development free from  environ-
mental pollution by directing the
modernization and cooperation
of removed enterprises (, in particular, minor
enterprises).'When executing the reclamation
project, in  addition to  the  reclamation and
development  undertaking,  undertakings for
removal  of factories,  etc.,  for utilization  of the sites of
removed factories, and for measures to cope with the change of fishermen's occupa-
tion for restoring the life of fishermen are needed as shown in Fig. 4, and these under-
takings are complex ones which are connected with each other.
In addition,  although  reclamation projects so far have been financed by  the money
paid in advance  by enterprises going into  the reclaimed land, Yokohama city itself
financed the reclamation project this  time by ensuring a source  of revenue with a
West German loan, and municipal loan, etc. in order to carry out the work systemati-
cally and steadily for  long periods based on the objective of developing sites for re-
development of the city.
               Diagram illustrating the removal
               of factories located in the streets
               of the city
552

-------
                                L_
                                    Measures to t ope with
                                    the change of fisherman's
                                    OLC upation
                         Plau-s for restoring    T    Compensation for
                         the life (Se.i pork)      |  L   fishery.
             Public sites tot rtitlds,
             spwaqe treatment plants, ,
             refuse incineration
I
Developir
!dnd
i
Burned
                               Ljnd pm e
U                                             Sites for redevelopment,
                                             sites for residents.
I The (i
I fundamental
I installations.
             of
           rban
The ror
novat of
*s, etc
 Dissolution of the
^ mixed existense of
                                        tl    Thes,teso,re
                                         | ^    TacTones.
                                 The utilization dnd redevelopment
                                 of the sites from which
                                 factories have been removed.
                                                           Direction & regulation
                                                          ''for preventing environ-
                                                           mental pollution
Fig. 4  Mutual relationship among undertaking accompanying the land reclamation project at Kanazawa.
22  Land use plan
     The area of the  reclaimed land is about 6,600,000 m2, and its length is about
7,000 m.
The gist of the planning for utilizing the reclaimed land is as follows:
 a.  The sites for rearranging sixty percent of the factories  requiring  removal  of
     about 2,000  factories scattered in the  object regions of redevelopment  of the
     city will  be assured, (the sites of removed  enterprises will be effectively utilized
     as part of the project for redevelopment of  the central part  of the city).
 b.  In the residential areas,  10,000 residences  accommodating 30,000 residents will
     be built,  eighty percent  of which will be residences for employees related to the
     factories  removed to the new sites, and the rest will be used for general citizens.
 c.  Along the existing coastal line, sites for arranging parks and green tracts of land
     in various places will be assured. As the basic arrangement of the planning for
     utilizing the reclaimed land, the loop  road of Tokyo  Bay is built on the central
     part of the land, the sites for removal of  factories are provided on the coastal
     side of the land,  and residential areas on the mountain side of the land, and fur-
     ther, a sea park  is located at the southern end of the land, its functions being
     distinctly scattered.  To  fulfil the objective of the project,  public utility sites of
     high civil demand for construction of sewage treatment plants, refuse and waste
     incineration plants,  parks, and roads,  etc. amount to about 48 percent  of the
     whole area of the reclaimed land. Divisions for utilizing the reclaimed land are
     shown in Fig. 5.
                                         553

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          ' \              .      Residential
            \ Kanazawa pumping    Hktrirt
          fcAstation             district   „
                                                                Torihama industrial
                                                              I  wastewater treatment
                                                             1£ plant No. 2
Collective
pretreatment
district
                   "Loop7oadofTokyo"Bay"j{~^   jt-Xvjj^
                                                           5rf\
                   i.ii J.,H  I  ^-'" Refuse & waste    Kanazawa
                   "—^   ' |  ^,  incineration plant  sewage
                    Industrial district	     treatment
                                    TOKYO BAY  plant
                                                                       t^j
                                                                     Torihama industrial
                                                                     wastewater treatment
                                                                     plant No. 1
              / ^Timber industry area
    *        ^
    Kanazawa Timber Pier
                                    Land No. 2
                                      (170 ha)  _^_ Land No. 1^ (193 ha) _
                                                            Collective pretreatment-J
                                                            facilities
                                                                          Kanazawa P.S.
        :__   Land No. 3 (227 ha)     _^_         _^_        .  ^       __
             Fig. 5   A plan of land utilization for the reclaimed land at Kanazawa

2.3  Sewerage system plan
     The   reclaimed   land   belongs   to
Kanazawa treatment district of the public
sewerage  system based on separate sewers.
     A plan of Kanazawa treatment district
is shown in Fig. 6.
     Collecting  sewage  from  the existing
town,  the trunk sewer goes  through  the
residential district of the reclaimed land to
flow into the sewage treatment plant.
     On  the other hand, wastewater from
the districts for removal of factories in the
reclaimed land flows into the  sewage treat-
ment plant through another  trunk  sewer.
The Kanazawa  sewage treatment plant is
located in the land No.l, and a  part of the
plant has  been operating  since  1979. The
plant is  characterized  by  the  fact  that
treatment facilities  are separated into two lines, one of them is for domestic waste-
water from the existing town and  the other is for industrial wastewater  from the
reclaimed industrial district.

2.4  Basic plan for a factory development
2.4.1  Removed factories
     Factories which  are to be  removed from  existing city streets to the reclaimed
land at Kanazawa are those  which need to be removed to realize the four objectives
of  improvement  urban environment,  strengthening the central  part  of  the city,
modernization of urban industries,  and recovery of green tracts of land in the city;
these are, the purposes of the project, and the  factories can be classified as follows:
 a.  Factories which  are obstructing the urban functions in areas that  are to be re-
     developed with priority, and in areas where the  mixed existence of residences
                                                                             Torihama I.W.T.P.
                                                                             Kanazawa S.T.P.
                                               Fig. 6
A plan of sewerage system in Kanazawa
treatment district
                                        554

-------
     and factories is marked.
  b.  Factories which are actually a source of environmental pollution.
  c.  Factories which are located in sites where public undertakings are scheduled.
  d.  Factories, of which grouping and cooperation can be effectively put forward,
     and which can  contribute to the modernization of the urban industry of the
     city.
     Of about 6,000 factories in the city, those which meet the above conditions are
about 2,000 factories, about 60 percent of which need to be removed.
     Moreover, the conditions of removal are as follows:
  a.  The enterprise is to fall into one of the following industrial categories.
     ® Manufacturing industry
     © Construction industry
     (3) Service  enterprise  (servicing  of  cars, other repair work, lease of industrial
       machines and tools, laundry cleaning, photography, and the like).
     (4) Wholesale business of reclaimed resources
     © Packing enterprise
     (6s) Distribution and processing  enterprise (enterprises where the removal was a
       necessity  as  confirmed by the City authorities, and the  warehouses  have
       already been resited).
  b.  Of enterprises which have their works and are conducting business in the city;
     those which remove their works.
  c.  Enterprises which  have sufficient funds to effect  the removal of their works
     and their management.
  d.  Enterprises which have completely paid their municipal taxes, etc.

2.42  Factory arrangement on the reclaimed land
     1,200 factories which are the object of removal have been arranged as follows so
that organic economical activities can be carried out efficiently based on the plan for
utilizing the reclaimed land.
Land No. 1: About 180 factories related to timber which will form a timber industry
           complex that is  centered on  Kanazawa timber pier (approximately 23
           ha)
Land No.2:' About 340 factories related to distribution, whose measures to cope with
           environmental pollution can be  implemented  without  difficulties.
           (approximately 31 ha)
Land No.3: About 680 factories which are short of technology and funds necessary
           for implementing  measures  to  cope with environmental  pollution.
           (approximately 113 ha)

2.4.3  Measures to cope with industrial wastewater in the Land No. 3
     Industrial wastewater discharged from factories into a sewage treatment district
can be treated by the following three methods:
 a.  Individual pretreatment
     Each factory is furnished  with  pretreatment  facilities by which the poisonous
     matter in the industrial wastewater is eliminated so that the wastewater is not
                                      555

-------
     troublesome to sewage treatment. After that treatment, the wastewater is dis-
     charged into the public  sewerage system,  and then its organic pollutants are
     treated in a sewage treatment plant.
 b.  Collective pretreatment
     After industrial wastewater containing  poisonous matter  has  been gathered
     together, and treated  in collective pretreatment facilities the wastewater is dis-
     charged into the public  sewerage system,  and then its organic pollutants are
     treated by a sewage treatment plant.
 c.  Direct discharge into the public sewerage system
     Organic wastewater which can be treated by a sewage treatment plant is directly
     discharged into the public sewerage system.
     To cope with industrial wastewater in existing urban area, factories have  been
required  to  furnish  their  own pretreatment facilities and the maintenance  and
operation of the installations have been assured by city authority inspectors. With this
method, it is difficult for minor enterprises short of financial ability and technology
to maintain  and  operate  the  pretreatment facilities  in  full accordance  with the
standards  of industrial wastewater. Therefore, to make the factory development free
from environmental  pollution in the  land No.3,  the treatment of  industrial waste-
water by a collective pretreatment method has been adopted positively for the minor
enterprises.
     The advantage of collective pretreatment method resides in the fact that, on the
enterprise  side,  the  wastewater of a  plural number of factories  can  be gathered
together and treated economically, and, on the administration side,  as close monitor-
ing of industrial wastewater can be carried out, the efficient and  precise instructions
as a result of the monitoring, can be performed.
     Examples  of wastewater suitable  for the collective pretreatment method are as
follows:
 a.  The pickling and plating processes, of which the treating process is complex, and
     the treating facilities are both expensive to  install and difficult to maintain and
     operate.
 b.  The  wastewater of printing and dyeing, of which the treating is anticipated to
     become  more  difficult   for  the new
     wastewater 'standards which have been
     laid  down  concerning the  regulation
     COD of the total amount and the color
     and so on.
     The wastewater of chemical industries is
     not suitable  for the collective pretreat-
     ment method, for its properties are not
     uniform  and it  is impossible  to mix
     simply the  wastewater from a number of
     different processes.
     Based on  the above  consideration, the
     treating method of industrial wastewater
     in the land No.3 has been determined as
     in Table 1.
Table 1.
Treating method of industrial
wastewater
Treating method
COLLECTIVE
PRETREATMENT
Individual pretreat-
ment
Direct discharge into
the public sewerage
system.
Type of wastewater
Plating wastewater
Pickling wastewater
Printing and dyeing
wastewater
Wastewater with oil
content
Wastewater of chemical
industries, etc.
Wastewater of foodstuff
processing, etc.
                                      556

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2.4.4   Arrangement of factories in the land No.3
     When thinking of the arrangement of factories in the land No.3, the basic way of
thinking is as follows.
 a.  Factories of the  same  type of industry and of related  types of industry are
     arranged in a mass.
 b.  On the mountain side  close to the housing developments, factories  of light
     work which produce little vibration noise are sited, and on the sea side, heavy
     industries or factories which have much work outdoors are sited.
 c.  Factories of the three types of industry of plating, pickling, and printing/dye-
     ing which require the collective pretreatment of their wastewater are arranged in
     a mass. Further, the location is  assured at  the center of the land No.3 as the
     three types  of industry are related to many other types of industry  such as
     metallic, mechanical, and textile industries.
     Based on the above conditions, the plan for the arrangement of factories has
been determined as illustrated in Fig. 7.
                           Residential Area
                                             - Foodstuff -
               Printing _
im"      1  (Industry
                                    £oodstyff-1 .Processing-, /— ™
                                    Processmg] industry  f   X\\
                                     ndustry       '	XV
                      Manufacturing   Iron Industry
                      Industry
                  Electrical F J*:-:m ««s'on~) fM55fSntal
                  Manufacturing.:.:.:.;.:.:-:  Mechanical] [lnrill,.tru s
                          SPickiing ^^PicklSng' ^Mechanical \^\^>
-------
Obiect factories
for removal
1 ,200 factories


Land No 3
680 factories






Land No. 1
(Factories
related to timber)
180 factories

Land No. 2
(Factories
related to
distribution)
340 Factories

                                    Table 2.   Number of object factories for the collective
                                              pretreatment of industrial wastewater
                      Individual
                      Pretreatment

                        or

                      Direct discharge
                      into the public
                      sewerage system
                      619 Factories
jval Dc-
fac tones
9
7
6
22
Future Remc
T
4
3
9
val Enterprises
**
16
5
9
30
Total
27
16
IK
61
                                         *l-nterpnses which are located on the Mies where public.
                                          undertakings are scheduled
                                         **Enterpnses involving the occurrence of environmental pollution
                                    Table 3.    The scale of enterprises by the number of employees
\Employees
Type of~\
Industry \
Plating
Industry
Pickling
Industry
Printing/
Dyeing
Industry
Total
Under 20
Persons
22
11
6
(64'<0
39
20-49
Persons
2
3
7
(209;)
12
50-99
Persons
1
1
4
OO'O
6
100-199
Persons
1
1
1
<5',;i
3
200
Per



(
                                                                               27

                                                                               16
                                                                              100',;.)
                                                                               61
Fig. 8
        Flow of the selection process of
        object factories
employees number under 100 account  for 94%, from which one of the character of
the reclamation project can be judged. Therefore, the collective pretreatment of
industrial wastewater has great significance.
                                          Table 4.   Site area of object factories
\ Type of
\Industiy
Item \^
Removal
Desiring
Factories
Future
Removal
Factories
Total
Plating
Industry
38,822
6,548
45,370
Pickling
Industry
27,720
18,682
46,402
Printing/ Dye-
ing Industry
29,717
42,898
72,615
Total
96,259
68,128
164,387
3.12  Site area of object factories
     Although the collective pre-
treatment  area is located nearly
at the center of the Land No.3,
when determining the site area of
object factories, the desired  area
of 22 removal desiring factories
was  asked  through  a question-
aire.  However,  there  was no
means with which to investigate  the desired site area of the future removal factories.
The  ratio of the increased site  area to an existing site area when a factory is removed
(That is, the desired site area after removal/the existing site area) was determined for
the removal desiring factories by the types of industries. By multiplying the ratio by
the existing site area of the future removal factories, the  site area after removal of the
future removal factories has been calculated. The result is shown in Table 4.

3.1.3  Wastewater collecting systems
     The process wastewater of the plating industry is divided into three types by its
nature:  cyanide type containing cyan, chromium type  containing hexavalent chro-
mium, and acid/alkali type  containing heavy metals.  And can be  divided  into two
                                       558

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Table 5.  Types of wastewater by the type of industry
Type of
Industry
Plating
Industry
Pickling
Industry
Printing/
Dyeing
Nature of
Wastewater
Cyan
Chromium
Heavy Metals
Acid/ Alkali
Acid/Alkali
BOD CDD
Color
Concentration
Intermittent
Wastewater
High Concent-
ration
ditto
ditto
ditto
ditto
	
Continuous
Wastewater
Low Concent-
ration
ditto
ditto
ditto
ditto
ditto
Table 6.  Wastewater collecting systems by types of industry
Type of Industry
Plating Industry
Pickling Indus try
Printing/ Dyeing
Industry
Wastewater Collecting System
High Concentration Cyanide
Line
Low Concentration Cyanide
Line
Chromic Line
Acid/ Alkali Line
Acid/ Alkali Line
Printing/Dyeing Line
The Number
of Systems
4
1
1
types by  its concentration:  the
wastewater of low concentration
that is discharged contenuously,
and  that  of high concentration
that is intermittently discharged.
     The  process wastewater of
the  pickling industry  is only  a
acid/alkali type containing heavy
metals,  and divided  into  two
types by  its concentration, one
of  them  is  low  concentration
type which is discharged continu-
ously, and the other is high con-
centration   type    discharged
intermittently.    The    process
wastewater   of   printing/dyeing
industry can not be divided by
its nature  and concentration.
     As the  wastewater  of high
concentration, which is small in
quantity, has a large load amount
because of its  high  concentra-
tion, it should be treated careful-
ly. As the wastewater of high cyanic concentration and that of low cyanic concentra-
tion must be treated  by different methods as  described later, they are separately
collected.  For chromic and acid/alkali, the special treating process of the wastewater
of high concentration has not yet been practised, so that the wastewater is treated by
pouring it uniformly into the wastewater of low concentration. Therefore, the waste-
water of high concentration and that of low concentration in chromium and acid/
alkaline are mixed in factories, and then discharged.
     Table 6 sets out the wastewater collecting systems by types of industry.

3.1.4  Planned water quantity
     The wastewater quantity from the object factories of the collective pretreatment
has been calculated by determining the unit daily mean wastewater quantity, and the
ratios of the daily maximum wastewater quantity and the hourly maximum waste-
water quantity to the daily mean wastewater  quantity according to the  types of
industry, and the nature and concentration of the wastewater.
 a.  The quantity of the low concentration wastewater
     (D The unit daily mean wastewater quantity
        The daily mean  wastewater quantity per unit area of the site has been taken
        as 1.67  m3/day . 100 m2  for the plating industry,  1.07 m3/day.100 m2  for
        the  pickling industry, and  3.60 m3/day-100 m2   for the  printing/daying
        industry, from the data  of  industrial statistics, the result of water supply
        quantity, and the investigated value of the removal desiring factories, etc.
      559

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    (D  The ratio  of the  daily maximum wastewater quantity to the daily mean
        wastewater quantity
        Based on the result of water supply quantity of the removal desiring facto-
        ries for the period of the past three years (1976 to 1978), the ratio of the
        daily maximum value to  the daily mean value  has been determined to be
        1.5.
    ®  The ratio of the hourly maximum wastewater quantity to the daily mean
        wastewater quantity
        The ratio  of the hourly maximum wastewater  quantity to the daily mean
        wastewater quantity  per unit time has been determined to be 2.5 for the
        plating and  the pickling  industries, and to be 2.0 for  the printing/dyeing
        industry, referring to the result values of Torihama industrial wastewater
        treatment plant, and the examples of five plants in other cities.
    ®  The  ratio of wastewater quantities by types of wastewater in the plating
        industry
        Although the wastewater of the plating industry is divided into three types,
        viz. cyanic,  chromic, and acid/alkali, the ratio of the wastewater quantities
        of the three  types has been taken as 23% for cyanic, 1% for chromic, and
        70% for acid/alkali through the hearing investigation of the removal desiring
        factories.
 b. The ratio of the  high concentration wastewater quantity to the low concentra-
    tion wastewater  quantity
    For the calculation of the quantity of the high concentration wastewater which
    is discharged  intermittently from the plating  and  pickling  industries, there are
    the following methods.
    © It  is determined from the volume of bath tubs in  factories and the replaced
        frequency by the type of wastewater.
        High concentration wastewater quantity = volume of bath tubs  x replaced
        frequency
    (D Based on the low concentration wastewater quantity, it is  calculated by
        determining  the ratio of the high concentration wastewater quantity to the
        low concentration wastewater quantity.
        High  concentration  wastewater  quantity = low  concentration wastewater
        quantity x the ratio
    (D It  is investigated through direct hearings from the  removal desiring factories.
    This planning has adopted the method No.2. The ratio for the various types has
been determined to be 2.2% for the cyanide, 0.4% for the chromic, 2.0% for the  acid/
alkali  of the plating industry, and 0.5% for the acid/alkali of the pickling industry by
the data of investigated values of the removal desiring factories, etc.
    From  the above, Fig. 9 shows the calculating process of planned wastewater
quantities, and Table 7 shows  the quantities calculated.
                                    560

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                                 Table 7.    Planned wastewater quantities
                                                                                                (m'/day)
^~\^Item
By type* ^\^
of Industry ^\^
By type of wastewater~-~.
Plating Industry
High cone.
Cyanic Wastewater
Low cone.
Cyanic Wastewater
Chromic
Wastewater
Acid/ Alkali
Wastewater (1)
Pickling
Industry
Acid/ Alkali
Wastewater
Printing/
Dyeing
Ind.
Acid/AlkaU(2)
Wastewater
(1H(2)
Total
Printing/
Dyeing
Wastewater
Low cone, wastewater q'ty
Daily Mean(:
—
85
49
325
495
820
2,614
[
) Daily Max*
—
130
74
488
743
1,231
3,921
4) Hourly
Max
—
215
125
810
1,237
2,047
5,228
High cone.
wastewater
quantity
daily max.
(5)
3
	
0.3
10
4
14
—
Storm(6)
water
etc.
0
0
0
0
74
74
392
Planned waste-
water q'ty
Daily
Mean
3+5+6
—
85
50
335
573
910
3,010
Daily
Max.
4+5+6
3
130
75
498
821
1,320
4,400
 Daily mean wastewater quantity per unit
 area of the site oy types of industry
         (rn3/claylOOm1}
   Plating Industry          1  67
   Pickling Industry         1  07
   Pnntina/Dyetng Industry  3.60
  SMC Area by Types of Industry
Ratios of the daily mdx wastewater q'ty
dnd the hourly max wastewater q'ty lo
the daily mean wastewater q'ty
   The daily moan       1 0
   The daily maximum   1 5
   T                   (2 0 (for printmq/dyeing)
   The hourly maximum  (,, g (f(jr £|ck|mjj ^ p^}
Storm water, etc
, Printing/Dyeing Industry ,
     Picklmq Industry

10% of the daily max low concentration
wastewater quantity
 Ratio of wastewater quantity by
 types of wastewater in plating mdustr\
   Cyantde wastewater       23%
   Chromic wastewater        7%
   Acid/alkali wastewater     70%
   Ratio of the high concentration
   wjstewater quantity to the low
   concentration wastewater quantity
      Cyanide wastewater    2.2%
      Chromic wastewater    0 4%
   Actd/Alkali wastewater
      2.0% for Plating Ind.
      0.5% for Pickling Ind.
Low ( oncentrdtion wastewater q'ty
       by types of industry
                                           Daily
                                           Mean
              Ddily
              Max
Hourly
Max
Low concentration wastewater q'ty
       by types of wastewater
                                           Daily
                                           Mean
             Daily
             Max.
Hourly
Max
Daily maximum
high concentration
wastewater q'ty by
types of wastewater
                                                            Storm water
                                                                etc
                 Fig. 9     Flow of the calculation of planned wastewater quantities
                                                      561

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3.15   Planned water quality
 a. The quality of the low concentration wastewater
    Table 8 shows the quality of the low concentration wastewater due to various
    kinds of data of the investigation, etc. of factories in the city.
             Table 8.  The water quality of the low concentration wastewater

                                                          Printing/Dyeing WasH-water
\\iypeot
\ \ Wastewater
\ Concentra-
\ don
Item ^\
Mean value of all data
The second highest
value of data
Adopted value
Cyanic Wastewater
(as cyan)
Mean.

I04
170
170
Max.

340
400
400
Chromic Wastewater
(as hexavalent (Jiro
mium)
Mean

113
104
110
Max.

430
580
580
^ AcWATVafi Waste-
water (as the total
amount of heavy
metals >
Mean

158
227
230
Max.

514
683
690
Pri
111
Mean

354
540
360
     For the reason that the mean and maximum concentrations of cyanic, chromic,
     and acid/alkali wastewater will tend to become higher hereafter as the factories
     will no doubt attempt to make a water saving, the facilities need to be given a
     certain degree of spare capacity, hence the  second highest value of examined
     data has been adopted.
     As there is little  data in which the  mean and maximum values of the concentra-
     tion of printing/dyeing wastewater are separately described, the mean value of
     all data has been taken as  the mean concentration, and the second highest value
     of the data has been taken as the maximum concentration.
     The quality of the high concentration wastewater
     As the major part of the high concentration wastewater is the  replaced liquid of
     bath tubs,  the concentration of plating baths and acid baths, etc. have been
     examined, and the mean value of all data has been adopted as  shown in Table 9.
                      Table 9.  Concentration of bath liquids
(mg/l!)
Cyanic Westewaler
Type
Copper
Plating

Zinc
Plating
Zinc
Plating
(Low
cyanide
bath)

Adopted
value


Concentration
Cyan 60,000-80,000
PH 12.2 - 12.6


Cyan 20,000-40,000


Cyan 10,000



Cyan 40,000
pH 13


Chromic Westewater
Type
Chromium plating

Chromium plating
(Barrel)
Hard chromium
plating
Hard chromium
plating

Chromate bath

Adopted value


Concentration
6 valent chro. 120,000
pH 2.4
6 valent chro. 180,000
pH 2.0
6 valent chro. 250,000
pH 1.8
6 valent chro. 220,000
pH 2.0

6 valent chro.
50,000 - 250,000
6 valent chro. 210,000
pH 2


Acid/ Alkali Wastewater
Type
Nickel
plating
Picric acid
waste liquid
Alkaline fat

Electrolytic
fat removing
liquid


Adopted
value


Concentration
Nickel 80,000
Zinc 12,000
Iron 70,000
pH 1.2
pH 13.2

pH 13 - 14




Total metals
70,000
pH Acid 1
Alkali 13
     Planned water quality
     As mentioned above, with both chromic and acid/alkali types, the high concent-
     ration wastewater and low concentration wastewater are mixed in factories, and
     then discharged into each sewage collection system. When mixed, the concent-
     ration is calculated by the following formula.
                                     562

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  Mean
  Concentration
  The maximum
  concentration
Mean of q'tv
the low concent-
ration wastewater
Mean q'ty of the
low concentration
wastewater
Mean concentration
x of the low concentra- +
tion wastewater
Mean q'ty of the low
concentration wastewater
The max. concentra-
x tion of the low con- +
ccntration wastewater
High concentration
wastewater q'ty
High concentration
wastewater q'ty
High concentration
wastewater q'ty
Concentration of the
high concentration
wastewater
Concentration of the
high concentration
wastewater
                            Mean q'ty of the low   + High concentration
                            concentration wastewater  wastewater q'ty
     The planned water quality determined in the above way is shown in Table 10.

                                                Table 10.   Planned water quality (mg/g)
Type of Wastewater
High concentration
cyanic wastewater
Low concentration
cyanic wastewater
Chromic
wastewater
Acid/ Alkali
wastewater
Printing/ Dyeing
wastewater
Item of Water
Quality
Cyan
Cyan
6 valent
chromium
Total amount
of heavy metals
BOD
COD
Mean
Value
40,000
170
1,400
1,500
400
550
Max.
Value
	
400
2,000
2,000
550
850
3.1.6  Arrangement of factories
     The site area of object factories of the
collective  pretreatment  is  approximately
172,500 m2, corresponding to 6 blocks of
divided sections  of the  land (1  block  =
32,800 to  34,000 m2). The conditions to
arrange  the  pretreatment  facilities  and
removed factories  effectively and econo-
mically in the six blocks can be arranged as
follows.
 a.  The collective pretreatment facilities are arranged in the center to minimize the
     total length of sewers. That is because the cost of construction and of mainten-
     ance and operation can  be reduced, measures for accidents such as the breakage
     of the sewers and prevention of the inlets for storm water, etc. can be minimiz-
     ed.
 b.  Factories are arranged in a mass by types of industry. That is because the econo-
     mical activities of factories  can  be  made smooth, and  also sewage collection
     systems can be prevented from being congested.
 c.  Plating factories are arranged close to the collective pretreatment facilities.
     That is because the construction cost of sewers  can be reduced in  plating factor-
     ies which require four sewage collection systems.
 d.  Sites for future removal factories are also arranged in a mass by types of industry
     for the purpose of making the division of factory sites more  flexible because
     future removal factories  have not decided individual sights and shapes yet.
     Considering the above conditions, the location of the pretreatment facilities and
the arrangement of factories  have  been determined as shown in Fig. 10. In addition,
as a model example of cooperation, the  example of the cooperative  association of
Yokohama plating factory development is shown in Fig. 11.
                                       563

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                  .•:•(Site for future •:..
                  '•.'•:••.•:•:•:•: removal )•:•;
:Printing/Dyeing Industry
1111111 ntSito for" '
      IV • ••••••••)••••••••••••••••••••••••
      • •••••••••••••••••••••••••••••••••
, -JlP|atin9 Industry
\ 'V;vr   '•
                                      •^'\o'thers\'\|
   Others in the figure means the factories which are not object factories
   of the collective pretreatment, but belong's Co. the same cooperative
   enterprise association as the object factories.
                                                                       3 Pickling Industry
                                                                      TZ! Plating Industry
                                                                         Printing/Dyeing Industry
                                                                         Cooperative enterprise associat.on
         enterprise association as the object factories.
Fig. 10   Plan view of the planned arrangement of drainage pipework of factories and pretreatment
         facilities and sewer planning in the collective pretreatment area
                  (Not belonging to cooperative association)
                         tor     A company.;-;.V.;.;•;.;•;•;•;•;•'
                         future        r-X^; •'•".£;•:• J~X'X'
                                                                       Plating cooperative
                                                                       society
                                                                  Box-culvert
                                                                                       BCo.
   Fig. 11
                                              Common access   Common access
                                                   Public road
      Plan diagram of the cooperative association of Yokohama plating factory development.
  3.2  Sewers
  3.2.1   Sewers plan
       As mentioned above, wastewater flows into the pretreatment facilities through
  one line for the type of industry in the printing/dyeing and pickling industries, and
  through four lines in the plating industry. As each enterprise is arranged in a mass by
  types  of industry (refer to Fig. 10, ground plan), the exclusive  sites for drain pipes
  have been assured  along the  site of each enterprise to minimize the total length of
  the sewers, that is advantageous for both the maintenance of the sewers and the con-
  struction  of lateral sewers for  the future removal factories. In the plating industry,
  for the following reasons, four  systems of piping have been accommodated in a box-
  culvert as shown in Fig.  12.
                                               564

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  a.  The whole aspect of the piping is accessible for inspection, and early detection
     of trouble is also possible. It is possible to rectify faults immediately, which will
     keep costs low.
  b.  There is  no possibility of incorrect installation, and the construction period of
     lateral sewers for future removal factories can also be reduced, and construction
     costs will be low.
  c.  In the case of a leakage accident, poisonous wastewater will not penetrate into
     the earth, so that damage can be prevented.
  d.  From both the view-points of maintenance and the construction cost, the box-
     culvert is more advantageous compared with open channels. Further, as piping
     material hard PVC pipes can be used.

3.2.2  Incidental equipment
  a.  Manholes
     On manholes, two types of lining are provided divided into the invert part affect-
     ed directly by wastewater and the wall body part. The invert part is made with a
     glass  fiber reinforced plastics lining (FRP lining) which has excellent chemical
     resistance, and is also reliable in the respect of water tightness, the wall body
     part is made of two sheets of tar epoxy resin  lining  with a layer of glass wool
     between them because they are inferior in chemical resistance.
 b.  Inlet
     When connecting the wastewater from factories to the sewers, an inlet is instal-
     led. The inlet is  provided with the three functions of mixing (except with the
     cyanic wastewater, to mix sufficiently the two types  of wastewater of low con-
     centration and  high concentration), metering, and  monitoring to determine
     accurately the quantity and nature of the process  wastewater and to  make
     maintenance and operation easy.
     Fig. 13 shows the structure of the inlet.
 c.  Flow meter
     For determining  accurately  the process wastewater quantity of each enterprise
     in order to  collect the appropriate charges, flow meters as shown in Table 11 are
     installed.
     For the plating industry and pickling industry, turbine flow meters have been
     adopted for the following reasons.
     (D They are easy to maintain.
     (D If faults occur, they are easy to repair, inspect, and change.
     (D For chemical resistant flow meters, they are  relatively inexpensive.
     ® They have been used for years as industrial flow meters.
     © It is possible for them to measure a small quantity (to the extent of 0.1 m3/
        h), too.
     Further,  for a high concentration cyanic wastewater, the measuring of flow
    quantity is carried out by a constant speed pump as the flow quantity is small.
    Moreover, in the wastewater of the printing/dyeing industry, foreign matter such
    as waste threads is commonly found, and  fluctuation in flow quantity is  large.
    Therefore, electromagnetic flow  meters have been adopted which can measure
    the flow rate electrically.
                                       565

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           3 500
           2 900
    4 DO  500 _, I 000
     '""pop Too
       KD-Q-©-i_
       Steel pipe pile
    Fig. 12   Box-Culvert
                —.   4 900     ^
               1350   2 200  1350
Table 11.   Flow meters by types of industry
~"~~~- — -_^Item
Type of industry"~-^— -___^
Plating
industry
High concentra-
tion cyan
Others
Pickling industry
Printing/dyeing industry
Flow meter
Constant speed
pump
Turbine flow
meter
Turbine flow
meter
Electromagnetic
flow meter
Material
PVC
SUS
sus
SUS
                                                              4900
                                                    Monitoring pit     Mixing pit
                     Monitoring pit \Mixingpit
                                     Fig. 13   Inlet
3.3  Pretreatment facilities
3.3.1   Design policy
     When designing the treatment facilities, the following items have been consider-
ed as constituting the basic concept.
 a.  The wastewater collected through five lines (high concentration cyan, low con-
     centration cyan, chromium, acid/alkali, and printing/dyeing) is separately treat-
     ed in each line for the following reasons.
     (D Water treatment
        •  Plating pickling wastewaters are different from printing/dyeing wastewater
           in nature and the chemical property of sludge, so they are separated.
        •  Low concentration cyanic wastewater is subjected to oxidation treatment,
           and chromic wastewater to reduction treatment which is the reverse of
           oxidation treatment, and is different from oxidation treatment in chemic-
           als used, so the cyanic line is separated from chromic line.
        •  Ferric ions present in acid/alkali wastewater make it impossible to control
           the injection quantity of  chemicals  in the reduction reaction of chro-
           mium,  so the chromic line is separated from acid/alkali line.
        •  As mentioned earlier, high concentration cyanic wastewater  has the level
           of concentration reduced by electrolysis treatment in advance, and then
                                     566

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           it is put into the low concentration cyanic wastewater line.
     (D Sludge treatment
        •  As printing/dyeing line sludge contains no poisonous materials, and can
           be treated in the same manner as domestic sewerage sludge, it is separated
           from other sludge containing metals, etc.
        •  As aftermentioned chromic and acid/alkali line sludge can  be successfully
           solidified  with asphalt etc. The  cyanic line sludge is  not  suitable for
           solidification, because cyan  might be dissoluted  from solidified sludge.
        •  So cyanic line sludge is separated from others.
        •  As chromic line sludge can be recycled as valuable matter, it is separated
           from the sludge of other lines.
        •  Therefore, acid/alkali sludge is separately treated too.
 b.  The flowing time of wastewater from each enterprise into the treatment facili-
     ties is taken as being 10 hours,  and the  operating time of the facilities is taken
     as being 24 hours with continuous treatment so that the scale of the  facilities is
     not made too large and uneconomical, by which the  necessary capacity and
     ability of the treatment facilities are determined.
 c.  The treated water is  recycled in an attempt to make a saving on running costs.
 d.  Automation is throughly carried  out for the certainty of treatment and for
     minimizing the number of operators necessary.

3.3.2  Design conditions
     Based on basic planned numerical values, design conditions have been establish-
ed as follows:
 a.  Treated water quantity
     The treatment ability of the facilities should be the planned daily  maximum
     wastewater quantity as described in the basic plan (3.1).
 b.  Quality of water  flowing into the treatment facilities
     The treatment ability of the  facilities  should be the  planned  water  quality
     determined in the basic plan (3.1).
 c.  Object items of treatment and the quality of treated water.
     The quality of treated water should meet the numerical values which  permit the
     treated water to be  discharged  into the public sewerage  system based on the
     discharge standards of sewerage law, and the  regulations of Kanagawa prefec-
     ture, etc. Table 12 shows the items of water quality, and Table  13 the quality of
     treated water.

                            Table 12.   Treatment items
Wastewater
High concentration cyanide wastewater
Low concentration cyanide wastewater
Chromic wastewater
Acid/alkali wastewater
Printing/dyeing wastewater
Water quality items to be treated
pH, cyan, copper, zinc, soluble iron, soluble manganese, nickel,
lead.
pH, hexavalent chromium, total chromium, copper, zinc, soluble
iron, solube manganese, nickel, lead.
pH, total chromium (except hexavalent chromium), copper, zinc,
soluble iron, soluble manganese, nickel, lead.
pH, appearance (coloration degree), extracted matter by n-hexane
extracts, temperature, iodine consumption, BOD, COD, SS.
                                      567

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                          Table 13.   Quality of treated water
Cyanide,
chromic,
and acid/
alkali line
Printing/
dyeing
line
Water
quality
items
Concen-
tration
Water
quality
items
Concen-
tration
PH
5-9
PH
5-9
Cyan
mg/fi
1
Hex-
avalent
chromium
mg/B
0.5
Apperance
(Colora-
tion degree)
200°
Total
chro-
mium
mg/fi
2
Copper
mg/S
1
n-hexane extracts
Fatty oil
mg/B
30
Mineral oil
mg/fi
5
Zinc
mg/e
1
Ten
pera
Soluble
iron
mg/fi
3
«•
ure
°C
45
Soluble
manganese
mg/fi
1
Iodine
consump-
tion
mg/e
220
Nickel
mg/B
1
COD
mg/e
200
Lead
mg/B
1
BOD
mg/e
300
SS
mg/e
300
3.3.3  Selection of treating methods
     The most suitable treating methods of wastewater have been selected consider-
ing the certainty, economy, operability, and results, etc. of the treatment from among
the methods now in practical use.
 a.  Plating and pickling wastewaters
     © Cyanide
        As the high concentration cyanic wastewater in the planning contains almost
        no iron and chromium, the electrolysis method is adopted.
        As the electrolysis method becomes less efficient when the cyanic concentra-
        tion is low, it is most suitable for the wastewater of high cyanic concentra-
        tion, and also it tolerates fluctuation in water quality and is easy to maintain
        and operate. In addition  heavy metals in  the wastewater are precipitated on
        electrodes, the quantity of sludge occurrence being reduced.
        For  the  treatment of low  concentration cyan, an alkaline  chlorination
        method has been adopted. The method can automatically control the treat-
        ment with a simple instrument which is easily to maintain and operate, and
        can  ensure the stable  quality of the  treated water. However, it is  charac-
        terized by the increased use  quantity of chemicals when the cyanic concent-
        ration is high. Further, after high concentration cyan has been reduced to
        the  cyanic concentration of about  1000 mg/£  by electrolysis, it is mixed
        with the low cyanic concentration wastewater, and the mixture is eventually
        treated to give a cyanic concentration of under 1 mg/£.
     (I) Hexavalent chromium
        For the treatment of hexavalent  chromium, a chemical reduction method
        employing sodium bisulfite has been  adopted. The method can be automati-
        cally controlled with  a  simple instrument which is easy to maintain and
        operate, and is capable of ensuring the stable quality of treated water.
        At  the  present  time,  although there is  an ion exchange method for the
        recovery of hexavalent chromium, for the treatment of the chromium the
        chemical reduction method has been adopted because the recycling planning
        for reutilizing the chromium has not yet been determined in the factories of
        participating enterprises.
     (3) Heavy metals
        Plating and  pickling wastewater  contains no  special metals such as mer-
        cury, etc., and also in Torihama industrial wastewater treatment platn the
                                     568

-------
       good quality of treated  water is  obtained by a coagulation precipitation
       method due  to the formation of hydroxides. Therefore, for the treatment of
       heavy metals, the coagulation precipitation method due to the formation of
       hydroxides has been adopted. The method can be automatically controlled
       with a  simple instrument, which  is easy to maintain and operate, and  is
       capable of ensuring the stable quality of treated water.
b.  Printing/dyeing wastewater
    For the decoloration treatment of printing/dyeing wastewater, the target water
    quality  can be  attained  only by  physicochemical  treatment. However, for
    organic matter of COD, etc., the target water quality cannot be attained only by
    a physicochemical treatment,  so  that  as an  after treatment,  a biological treat-
    ment  which is  effective for  the  elimination of organic matter is carried out.
    For the physicochemical method, a floatation method has been adopted which
    can tolerate fluctuation in water quality, is  easy to maintain and operate, and
    requires only a small site area. For the biological treatment, a rotary disc method
    has been adopted which is easy to  maintain  and operate, and is economical to
    run.
c.   Treatment of sludge product  from each wastewater  treating  process Table 14
    shows the estimated quantity of sludge  produced.

     Table 14.  Quantity of sludge produced by various types of wastewater at each process
^\^
Cyanide wastewater
Chromium wastewater
Acid/alkali wastewater
Hinting/
dyeing
waste-
water
Floatation
sludge
Rotary disc
sludge
Settled sludge
Quantity
(m3/day)
8.0
26.0
446.6
250.0
53.2
Moisture
content(%)
99.2
99.2
99.2
98
99.2
Thickened sludge
Quantity
(m3/day)
3.2
10.4
178.6
-
21.3
Moisture
content(%)
98
98
98
-
98
Sludge cake
Quantity
(t/ day)
0.3
0.83
14.3
36.2
Moisture
content(%)
75
75
75
85
     Note: The moisture content of settled sludge and thickened sludge is based on the results obtained
         by Torihama industrial wastewater treatment plant.

    As cyanic sludge and chromic sludge are only produced in small quantities, two
    batchwise thickeners which can remain idle for a considerable time are installed,
    and are used alternately every other day and also fulfilling the role of a sludge
    storage tank.
    As acid/alkali  sludge  is produced in  large  quantities, a continuous thickener
    which may have a small capacity is used for the sludge.
    Further,  as the rotary disc sludge of the printing/dyeing line, which is organic
    sludge, only occurs in small quantities a  batchwise thickener is adopted for the
    rotary disc.
    From  the previous results, for the sludge of cyanic,  chromic, and acid/alkali
    lines pressure  filters have been adopted as dewatering facilities,  and for the
    sludge of the printing/dyeing  line centrifuges have been adopted as dewatering
    facilities.
                                        569

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3.3.4  Treating process and main equipment
     Fig.  14 shows each treating process. Table 15 to 20 give a synopsis and list the
equipment content of each treating process.

             Table 15.   Treating process of a high concentration cyanide line
Equipment Name
Pumping well
which also
serves as a
storage tank.
Electrolytic
cell
Synopsis
As high concentration cyanic
wastewater may be discharged
instantaneously in a mass from
each factory, the capacity of
storage tank is increased to
ensure uniformity and homo-
geneity in water quantity and
water quality.
Cyan is electrolyzed.
Retention time
and capacity
7 days
Ilm3x2 tanks
22 hours
Batchwise
treatment
1.5m3 x2 tanks
Treating
conditions
-
Voltage
appr. 10V
Current
6 to IDA
Chemical
to be used
-
-
Specification
An FRP tank
is installed
inside a conc-
rete tank.
Made of steel
plate, and the
inside has a
rubber lining.
            Table 16.  Treating process of a low concentration cyanic line
Equipment
Name
Pumping
Well
Storage
Tank
Primary
Oxidation
Tank
Staying
Tank
Secondary
Oxidation
Tank
pH Control
Tank
Coagula-
tion Tank
Sedimenta-
tion Tank
Pumping
Well
Sand Filter
Sludge
Thickener
Dewatering
Filter
Synopsis
Wastewater which flows into a pumping
well from sewers is pumped up into a
storage tank.
Wastewater which flows into a pumping
and homogeneity in water quantity
and water quality to stabilize the
operation of the treatment facilities.
The primary oxidation reaction of cyan
is carried out in the tank.
It enhances the reaction efficiency of
the primary oxidation reaction, and
also prevents the short circuit flow
from the primary oxidation tank to
the secondary oxidation tank.
The secondary oxidation reaction is
carried out in the tnak.
pH is adjusted to form the hydroxide
of heavy metals.
Floccules are coarsened to give the
formed hydroxides of heavy metals
a better property of sedimentation
It separates liquid and solid by the
sedimentation of floccules of heavy
metals.
From here, the supernatant in the
sedimentation tank is pumped up
into a sand filter.
Fine floccules in the supernatant of
the sedimentation tank are removed
by the sand filter.
Sludge separated in the sedimentation
tank is tnickened here.
The thickened sludge is dewatered by
the dewatering filters.
Retention time
and Capacity
15 minutes
8m3
1.6 days
115m3 x2
tanks
1 hour
6.2m3
1 hour
6 2m3
1 hour
6.2m3
30 minutes
3.7m3
10 minutes
1.0m'
3.5 hours
22m3
overflow rate
20m3/m2-day
15 minutes
1.4m'
01.2mx24m
2 filters
Iday
9.7msx2 tanks
Operation for
6 hrs 1 unit of
equip.
Treating
Conditions




pH over 10
ORP
300-350
mV


pH under 8
ORP over
650mV
pH 9-10












Chemicals
to be used




5% Caustic
Soda, 12',!
Sodium
Hypochlo-
rite

5% Sulfuric
Acid,12%
Sodium Hy-
pochlorite
5% Caustic
Soda
0.1% Poly-
met Coagu-
lant










Specifications
A concrete tank, of
which the inside wall
is coated with tar
epoxy resin.
Ditto
A steel plate tank, of
which the inside wall
is coated with tar
epoxy resin
Ditto
Ditto
Ditto
Ditto
Ditto
Concrete tank
A pressure type rapid
filter, filtration rate
150m3/m2-day, filtra-
tion area 1.1 3m2 /unit
Batchwise, sludge for a
day Is put into a tank,
a concrete tank.
A pressure filter, Filtra-
tion rate 1.8kg/mJ-hr
Filter area 22ma /unit
                                        570

-------
Ol .

Hign cone. CN Pump v,eil-*-p««rolvJis,
wnuwater3m>/day | |
,, . _., . (Tdavsl 122 hours)
High cone CN line |

1 	 ' _5% NaOH f— 5% H,SO.
| | f- 12% NaCIO 4f-12%NaCIO (-5% NaOH, — 01% polymer Supernatant
MKtcwntcrCN » PumD ®- rtoragc ®» p'"" *• "loving • 2 nj d » °H 1 „ Coagulation _^ Sedimen- i ^ p,,mp
"^*B"r*™ well a " oxid " " iiiuuAiu Control A tation well
1
1
(ISmml 116davs)i (1 hr) (1 hr) (1 hrl (30 m.n ) | (lOmin) gj(35hrs) (15mm
1 5% NaOH 1 "SI
' 1 <" II
1 *
1 1
1 1 Thickener—  , H5 mm)
tfy Sludge Supernaram
| _^ 	 Cake
Chromic Line i 	 1 	 I
' 1
1 S
1 1
1 1
Is 5
Is
r?5%H,S04 r20% NaOH rA.r /^ Na° p-0 1% Polymer j|
.^i?la..k'1^ ^ P,,mn i *^ Storaoe ,*. Ac,dii-ca .on » Prim ' ,_ n dotirl ^ 2nd ' f Jcoaauiait'on ^ Sed.men- ^ Pump
i well *" PH conuoi " pH control i | [ tation - well
115 mm) (1 day)f (5 mm) 130 mm) (3 hr) ,JO nrn) | llOmmJ | (3 5 hr s) S 1 15 mm

! Return 1 __«_^ Sludge
wdter Thickener™*®* Storage
— 
-------
Table 17.   Treating process of a chromic line
Equipment
Name
Pumping
Well

Storage
Tank

Reduction
Tank
pH Control
Tank
Coagulation
Tank

Sedimenta-
tion Tank

Pumping
Well

Sand

Sludge
Thickener
Dewaterrng

Synopsis
Wastewater which flows into a pump-
into a storage tank.
The tank ensures uniformity and
water quality to stabilize the operation
of the treatment facilities.
Hexavalent chromium is reduced to
trivalent chromium.
pH is adjusted to form the hydroxide
of heavy metals. However, for the
reason that the pH of the overflowing
water from a reduction tank differs
markedly from the pH setting, and the
formed hydroxide of chromium is
redissolved when alkali is injected in
excess, the control process has been
divided into two stages.
Floccules are coarsened in the tank to
metals a better property of sedimenta-
tion.
It separates liquid and solid by the
sedimentation of floccules of heavy
metals.
From here, supernatant in the
a sand filter.
Fine floccules in the supernatant of the
sand filter.
Sludge separated in the sedimentation
tank is thickened here
The dewatering filter dewaters the

Retention time
and Capacity
IS minutes
3 5m3

1.6 days
60m3 x2 tanks

30 minutes
1.7m3
1st stage
IS minutes
2nd stage
30 minutes
1.7m3
10 minutes
1m3

3.5 hours
16m3
Overflow rate
20m3/m2-day
15 minutes
0 8m3

00.9mx2.4m
2 filters

Iday
27m3 \2 tanks
Operation for
of equip.
Treating
Conditions




pH under 3
ORP under
250mV
pH7
pH9








	


Chemicals
to be used




10%Sulrur-
ic Acid.10%
Sodium
Bisulfite
20% Caustic
Soda
50% Caustic
Soda
0.1%
Coagulant






	


Specifications
A concrete tank with a



A steel plate tank with
a rubber lining
A steel plate tank witn
a rubber lining
A steel plate tank of
coated with tar epoxy
resin
A steel plate tank of
which the inside wall is
coated with tar epoxy
resin
A concrete tank

Pressure type rapid
0.63m2/filter, Filtration
rate 150m3/m!. day
Batchwise. Sludge for a
day is put into a tank.
Two concrete tanks
A pressure filter, Filtra-
Filtration rate 1.8kg/m2-hr
                 572

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Table 18.   Treating process of a Acid/Alkali line
Equipment
Name
Pumping
Well
Storage
Tank
Acidifica-
tion Tank
Primary pH
Control
Tank
Oxidation
Tank
Secondary
Control
Tank
Coagulation
Tank
Sedimenta-
tion Tank
Pumping
Well
Sand Filter
Sludge
Thickener
Sludge
Storage
Tank
De watering
Filter
Synopsis
Wastewater which flows into a pump-
ing well from sewers is pumped up
into a storage tank.
The tank ensures uniformity and
homogeneity in water quantity and
water quality to stabilize the operation
of the treatment facilities.
When the water flowing into the line
has become strong alkaline, it is no
longer possible to control the process .
As a measure to cope with such an
emergency, an acidification tank is in-
stalled, in which wastewater into the
line is acidified.
pH is controlled to form the hydroxide
of heavy metals.
Bivalent iron is oxidized to trivalem
iron by aeration.
The difference between the pH of the
water flowing into the line and the pH
accurately only by the primary pH
control tank, h'or compensating for
the primary pH control and for further
adjusting the pH value which is changed
by the aeration oxidation, the secondary
pH control is carried out.
Floccules are coarsened to give the
formed hydroxides of heavy metals a
better property of sedimentation.
The tank separates liquid and solid by
the sedimentation of floccules of
heavy metals.
From here, the supernatant in the
sedimentation tank is pumped up into
a sand filter.
Fine floccules in the supernatant of the
sedimentation tank are removed by a
sand filter.
Sludge separated in the sedimentation
tank is thickened here.
The thickened sludge is stored in the
tank before dewatering.
The filter dewaters the thickened
sludge.
Retention time
and Capacity
IS minutes
S4ms
1 day, 910m1
x 2 tanks
5 minutes
6.9m1
30 minutes
39.3m3
3 hours
230.6m1
30 minutes
39.3m3
10 minutes
12,7ms
3.5 hours
285 m3
Overflow rate
20mVm2-day
IS minutes
14.4m1
03.5mx2.4m
3 filters
12 hours
235m1
For a half day
95m1
Operation for
S houis
2 units
Treating
Conditions


	
pH under 7
pH9-10
	
pH9-10


	 „
	 —
	 	 .
Solid
matter
load 60kg/
mj-day
	
	 _
Chemicals
to be used


	 —
75% Sul-
furic Acid
20% Caustic
Soda
	 	
5% Caustic
Soda
0.1%
Polyrflcr
Coagulant
	
	
— ' 	
	
	
	 ,
Specifications
A concrete tank with an
FRP lining inside.
Ditto
A steel plate tank with
a rubber lining
Ditto
A steel plate tank coated
with tar opoxy resin inside.
with « surface aerator.
D(ttQ
Ditto
Circular radial flow type.
Made of concrete.
Made of concrete
Pressure type rapid filtra-
tion, Filtration area 9.8m1/
filter. Filtration rate 150m'/
m'-day
Continuous type, Made of
concrete
Made of concrete
Pressure filter, filter area
154m*/unit, filtration
rat* 2.0 kg/m'-hour
                         573

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Table 19.   Common process of Cyanic, Chromic, and Acid/Alkali lines
Equipment
Name
Pumping
Well for
Reverse
Washing
Ion
Exchange
Column
Final
pH Control
Tank
Discharge
Water
Tank
Synopsis
The pumping well receives water flow-
ing out of the sand filter of each line
and stores it in readiness for reverse
washing of each sand filter. It also
serves as a pumping well for pump-
ing water out into each ion exchange
column.
It will adsorb heavy metals that cannot
be removed by the coagulation
precipitation method due to the
formation of hydroxides of heavy
metals.
As pH is 8 to 10 when the hydroxides
of metals are formed, the pH is
controlled to heavy before discharging
the water.
It is used to store created water which
may be needed for the purpose of
dissolving chemicals, etc.
Retention time
and Capacity
20 minutes
95m1
1520m'/day
2 units
SV20m3/
m' -h
30 minutes
36.6m3
80m3 \2tanks
Treating
Conditions




pH 7


Chemicals
lobe used


When repro-
duced 1.2V,
Hydrochloric
Acid.8%
caustic
Soda
y/i Caustic-
Soda
5"' Sulfunc
Acid


Specifications
A concrete tank
A cylindrical vertical
pressure tank made of
steel plate, which has
a rubber lining inside
A concrete tank
A concrete tank
       Table 20.   Treating process of a Printing/Dyeing line
Equipment
Name
Pumping
Well
Storage
Tank
Coagulation
Tank
Floatation
Tank
Rotary
Disc
Tank
Sedimenta-
tion Tank
Sludge
Thickener
Sludge
Storage
Tank
De watering
Equipment
Synopsis
Wastewater which flows into a pumping
well from sewers is pumped out into
a storage tank.
It stores wastewater that Hows into it
from factories tor a period of 10 hours;
the water is then treated continuously
for a period ot 24 hours. Also, surface
aeration is earned out for the homoge-
neity of water quality and for the pre-
vention of putrefaction of wastewater.
In the tank, the pH of wastewater is
adjusted, and flocculant is added to
flocculate fine suspended matter.
It mixes flocculated particles with
pressure water to float and separate
them.
In the tank, the organic matter in
wastewater is decomposed.
In this tank is precipitated and
separated the excess sludge which
occurs in the rotary disc tank. In
addition, before the sludge flows into
the sedimentation tank, polymer coagu-
lants are added to the sludge to give it
a better property of sedimentation.
It thickens the sludge separated in the
sedimentation tank.
It stores floatation sludge and thick-
ened sludge before the dewatering
process.
It dewaters sludge

* 25 minutes
air/solid ratio 0.04kg air/kg-ss
pressure 4kg-F/cm2
Floatation rate 4m/hr
Water quantity
circulation rate 0.76
74m3x2 tanks
Retnetion time
and Capacity
15 minutes
145.2m3
For 0.6 day
2810m3
30 minutes
50m3 \2tanks
*
1.3 hours. BOD
disc surface
loading 20g/m 2 •
day
2.1 hours
Water area load
35m3/m2-day
191m3x2
tanks
1 day
53m3x2 tanks
One day
147m3
Operation for
20 hours
2 units
Treating
Conditions


	
pH 7


	








Chemicak.
to be used


	
20',! Caustic
Soda,8%
Alumearth
0.1% Poly-
mer
Coa^ulanls


	






0.2%Poly-
mer
Coagulants
Specifications
A concrete tank
A concrete tank
Surface aerator
(float type)
A steel plate lank, ol
which the inner wall is
coated with tar epoxy
A steel plate tank, of
which the inner wall
is coated with tar epoxy.
Tank is made ol concrete,
and disk is made of
plastics
Circular radial (low type
Made of concrete
Batchwise, sludge for
one day is put into a
tank. Made of concrete
A concrete tank
Centrifuge 10m3/
hour/unit

                              574

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3.3.5  Planning for the arrangement of facilities
     Conditions and the way of thinking for carrying out planning for the arrange-
ment of facilities are as follows:
 a.  Conditions for installing buildings on the reclaimed land are as follows:
     ®  Ratio of the  area  of green  tracts of land  — over 20 per cent (in the case of
         public facilities)
     (D  The building-to-land ratio  - under 60 per cent
     (3)  Volume ratio              - under 200 per cent
     ®  Height limitation          - under 31 meter
 b.  The way of thinking for the arrangement of facilities are as follows:
     ®  As the treating processes are divided into many lines such as cyanic, chromic,
         acid/alkali, and printing/dyeing line, they are broadly divided into metallic
         lines and printing/dyeing line, and further, the metallic lines are arranged so
         that each treating process is distinguished distinctly.
     (2)  Each treating process is arranged almost in a straight line from inflow to out-
         flow to make the flow of treatment as short as possible.
     (3)  Water  flow between each  unit of facilities  should  relay on gravity flow
         wherever possible to achieve energy saving.
     ®  The printing/dyeing system is arranged to  facilitate an  additive installation.
     (§)  For eas"e of  bringing  in  of equipment,  and chemicals, and taking out of
         sludge, etc., a circumferential road is suggested for the site.
     Fig.  15 shows  the arrangement of facilities based on  the above  conditions and
     way of thinking.
     As shown  in Fig.  15, on  the inflow side, storage facilities are installed, and in
     its upper part, each treating facility is installed.
     On  the outflow side, an electromechanical  room is provided, in which sludge
     treating facilities  and  facilities for control and  monitoring  are arranged, and
     space related to a living room is ensured, too.
                                               *1 Low concentration cyanic
                                                  line treatment facilities
                                                *U. <•> ,„„. & nm® ,„„©
                                                   3Chromic line
electromechanical
room
       &
       §
                                        Acid/AI kal i
                                        sedimentation
                                        tank
                  Dewatering
                 -filter room
                   t   Final pH co
                                                                __*Staircase
                                                                -i! • room
                                                                 :|        Inflow
                                                                 ii"*'	side
                                                                ,*2 High concentration cyanic
                                                                  line treatment facilities

                                                                  Chemicals
                                                                  storage
                                                                  tanks
                                                                *5 Printing/Dyeing line
                                                                  treatment facilities
                                                                 Staircase
                                                                 room
   ^.Discharge 2	
     Side     '
                              ..^Printing/Dyeing..
                               sedimentation
                               tank
                                 Fig. 15   Plan of facilities
                                        575

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3.3.6  Control
     As the facilities treat industrial wastewater by five separate lines, many machines
are incorporated such as small capacity machines of lift pumps and stirrers, etc., and
filtering  equipment and  electromagnetic  valves, etc.  are  also  provided. It would
require  a great  deal  of manpower  to operate manually many of  these machines
separately, therefore, a control  circuit has been designed to operate each machine
automatically by a water level control or timer, etc.
     However, if necessary, each  machine can be manually operated from a central
control room,  and when inspecting  any  machine, it can be operated from  a  local
control panel close by.
     The  operation condition and failure condition of machines  are automatically
displayed individually in  the central control  room; a system which  makes one man
control possible is being established. When injecting chemicals into each treating tank,
the necessary quantity of chemicals according to proportional calculation operation
control which  takes  pH  and ORP as targets is automatically injected  by a digital
controller.
     In addition, all information of the facilities is transmitted to  Kanagawa sewage
treatment plant by remote  monitoring equipment. Therefore, it is possible even for
the operators of the  sewage treatment plant  to monitor the pretreatment  facilities.
Fig. 16 shows the control flow of the chemical injection system of 20 percent caustic
soda as an example of automatic control systems.
     The injection of chemicals  by the conventional ON-OFF control system has not
been adopted in this case,  instead,  a continuous control system has been adopted
whereby chemical injection is carried out  by  the proportional calculation operation
control of which the detective  tip of pH or  ORP for  increased  controllability. The
injection points of  chemicals are so many  that a system for controlling the injection
quantity by installing a variable speed motor at each injection point is questionable
from the view point  of construction  cost and  maintenance and control. Therefore,
in the  adopted  injection  system,  two injection pumps have been installed for each
chemical, and the control of the injection quantity has been carried out by air operat-
ing valves. Further, for such chemical injection of a large quantity  range as caustic
soda injection into  a  pH control tank of the chromic line, the necessary quantity of
chemicals is injected through a plural number of installed injection pipes of different
caliber. Moreover, the pressure control loop of Fig. 1 6 controls pressure in the supply
pipes of a chemical  at a constant level to stabilize the pH control loop.
Fig. 16
       Legerd
        |    I  Microcontroller
              Air operating valve
              Electromagnetic valve
              Pressure control loop
             (Operation part)
              pH control loop (Calculator)
              Hand controls
              Alarm
              Process value
              Set value
              Manipulated value
        Example of the control
        process of chemical
        injection
                                    Pressure control loop
                                                             contml lo°P
         PC

         PHC
         HC
         A
         PV
         SV
         MV .




ulator)
Caustic soda
solution I
tank 1 L

Caustic soda.
solution I
tank 2 *~


*<£=-. [!h*



r 1

-- -t
>
i
•H
. j|*
r
i
'r-*
r'p)-


V1-


T
j MV

~1 "* Electromagnetic
valve switching
I command
rJ£-


1
fl
L
/
Pressure
gauge
, , ••"
d. ^ 	
— \XrVQ — -
Ditto

1$ <
j-*-oS 	
L»^ 	

Jji.
~~|


11 iipH meter
+ 1 1 Acid/Alkali
' prim. pH control tank
Ditto
-^ | i pH meter
' i Chromic pH
i control tank
	 	 Printing/Dyeing coagulation tank
                                      576

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3.3.7  Sludge disposal plan
     As dewatered cake from the printing/dyeing line is organic sludge, it is possible
to dispose of the sludge in the same manner as domestic sewage sludge. On the other
hand, dewatered cake from each wastewater treatment  line of cyanic, chromic, and
acid/alkali lines contains a large quantity of cyan, chromium, copper, lead, and other
heavy metals, so that its disposal should be carefully considered.
     At the present time, in Japan laws and regulations prescribe judgement standards
for the final disposal of industrial waste  matter. Although it is considered  to be
possible to dispose of the dewatered cake  containing metals,  etc. by land disposal
from the  result of  Torihama industrial wastewater treatment plant, the possibility of
solidification disposal methods of higher safety is being examined from a long term
prospect.
     Table 21 shows the outline  of solidification experiments with asphalt, cement,
and  plastics, and by melting, etc. using the dewatered  cake of Torihama industrial
wastewater plant.
     When each solidification method is evaluated only by the result of dissolving out
tests without taking into  account economical factors, the solidification method by
melting is the most safe for all kinds of sludge. But, for the sludge of chromic, and
acid/alkali lines  containing no cyan, the solidification method with asphalt or cement
can  be  adopted. Although the adoption of the melting solidification method as  a
technologically permanent disposal method  is the most desirable, its high cost is the
question,  for all the  construction costs, etc.,  are, in general, to be  borne by the
associated enterprises. Therefore, in Kanazawa  industrial wastewater collective pre-
treatment facilities, the solidification with asphalt, etc.  of the  dewatered cake from
chromic,  and acid/alkali lines is executed, and the melt  solidification method of the
dewatered cake from the cyanic line is being examined.

             Table 21.   Technical comparison of various solidification methods
                                      Basn. conditions
                                      1) Sludge take containing heavy metals, etc , 1 r eat men t quantity, I t/day
                                                 *"""        , Moisture content , 75%
                                                 Ditto
                                      2) Working hours ,6 hours
                                                            ,Organic matter content, 20%
Item
Type
Lxplanation ol
Methods
Mi\w? Ratio
Dissolving
Out Test
Analysis,
Item
Solidified
Mattel
In water
6 months
80°C,20days
exposure
Operation &
maintenance cost
(¥ 1,000/t (wet cake})
Construction (¥= 10
cost Mil)
Micro Wave Melting
When irradiating micro-
waves are directed onto an
equal weight nuxture(,ol
sample sludge and the
incinerated ash of sewage
sludge, mainly the silica
matter in the ash is fused
and crystallized
Sludge cake Incinerated jsh
1 1 (Wet wcifftt)
CN
o
o
0
Ct*
O
o
o
1-Cr
o
-
u
140
43
Solidification with Asphalt
Asphalt forms films on the
surface of sample sludge, and
when the sludge is molded by
compression, spare between
particles within the solidified
matter is reduced, the contact
of heavy metals with environ-
mental water being prevented
Sludge cake Asphalt
1 0 }7
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4.   Bearing of the Expenses
     The industrial wastewater collective pretreatment  facilities in this district are
constructed, maintained, and operated by Yokohama city, and all the necessary ex-
penses are borne by the associated enterprises in principle.
                                              Table 22.  Enterprise expenses by types
                                                        of construction
                                                                Unit: 1,000 yen
4.1  Construction costs and financial sources
     The total construction cost of the facili-
ties  amounts to  about 3.9 billion yen. The
breakdown of the construction cost by types
of construction is shown in Table 22.
Enterprises  must  deal  responsibly  with en-
vironmental pollution,  etc., which occurs as
a direct result of their activities for they are
the  source  of the  pollution.  But,  in parti-
cular, it is in  many ways  difficult for minor
and  mini-enterprises to solve the pollution
problems effectively by themselves.
     The  Environmental Pollution Control Service Corporation is dealing with the
allocation of funds for  installing environmental pollution control facilities. Table 23
shows the financing system of the corporation. With the system, object enterprises for
financing  include local public  bodies, and  lending conditions are advantageous for
minor enterprises and local public bodies. Therefore, Yokohama city has determined
to make available the funds for the construction cost of the facilities.
 Table 23  Financing system of the Environmental Pollution Control Service Corporation
Type of Construction
Sewers
Treatment
Facilities
Concrete Structure
Building
Machines
Electric Equipment
Site Expenses
Office work Expenses
Total
Cost
473,000
646,000
443,000
1,096,000
570,000
633,640
22,000
3,883,640
Object
facilities
of
financing
Collective
environmental
pollution
control facilities
Individual
environmental
pollution
control facilities
Objects of
financing
Minor
enterprises
and local
public
bodies
Major
enterprises
Minor
enterprises
and local
public
bodies
Major
enterprises
Ratio of
financing
Under
80%
Under
70%
Under
80%
Under
50%
Term of redemption
(Including unredeem-
able term)
Machines or
equipment
Within
10 yeais
Others
Within
20 years
Within 10 years
Unredeemable term
Machines or
equipment
Within
1 year
Others
Within
3 years
Within 1 year
Rate of interest
(Annual int. rate)
For three years
after financing
6 35%
765%
After the fourth year
after financing
6.85%
7 85%
7.00%
7.85%
4.2  Calculation for sharing of costs
4.2.1  Distribution of shares in construction costs
     The object enterprises of this project are of various types ranging from enter-
prises having only printing/dyeing wastewater or only acid/alkali wastewater to enter-
prises having two,  three, or four kinds of acid/alkali, chromic, high concentration
cyanic, and low concentration cyanic wastewater. Therefore, the sharing of construc-
tion costs has been calculated as follows.
 © At first, out of the each cost of sewers, equipments and land, the portions which
     could  be considered to be  apparently  depended  upon the kinds of industries
     were calculated.
                                     578

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  (2) The cost concerned witli metal plating industry was, further, subdivided into
     four portions by the properties of the wastewater.
  V3> Then,  the  cost of common facilities concerned with several  industries and/or
     wastewater treatment  processes was divided  into  several  parts  based  on  the
     factors such as wastewater quantity and quality load, electric load, sludge weight
     etc.
  (4) Finally, the total cost was alloted  to each enterprise based on their discharging
     volume by  the kinds of wastewater.
4.2.2   Calculation method of individual share in the costs
     The individual share in the costs of each enterprise has been calculated from the
following formulae.
 Printing/Dyeing Ind.= (Share in the cost of Printing/Dyeing Industry) x (p,Mned wa^ef quantity (40o m
Pickling Industry

Plating Industry
= (Share in the cost of Pickling Industry)   x

_/Share in the cost distribution of  \
~ Mhe high concentration cyanic line '

 /Share in the cost distribution of  \
 ^-the low concentration cyanic line '
h /-Share in the cost distribution of
  nlie chromic line
  /Share in the cost distribution of
'"v the acid/alkali line
                                            -.
                                            '
,The water quantity of each enterprises,
^Planned water quantity (747 m3 /day) '
/The water quantity of each enterprises-*
 Planned water quantity (3 m'/day)
.-The water quantity of each enterprises\
 Planned water quantity (130m'/day)
.-The water quantity of each enterprises-.
^Planned water quantity (75 mj/day)
/•The water quantity of each enterprises-.
^Planned water quantity (498 m' /day) '
     Table 24  shows  the construction  costs per one cubic meter of wastewater cal-
culated  from the above,  which is a little less expensive than if each enterprise was to
build separately its own pretreatment facilities.
                           Table 24.   Construction cost
                                                      (V1000/mJ)
Types of
Industry
Construe
tion Cost
Plating Industry
High Concentration
Cyanic Line
41,300
Low Concentration
Cyanic Line
1,550
Chromic
Line
3,230
Acid/Alkali
Line
1,070
Average
1,560
Pickling
Industry
1,270
Printing/
Dyeing
Industry
420
4.2.3   Contract of bearing of the construction costs
     Yokohama city has drawn  up a contract for bearing of the construction costs
and so on with each enterprise. The main points of the contract are as follows.
 a.  Bearing of the costs
     The city draws up a  contract of wastewater quantity by types of wastewater
     with each enterprise.  Based on the contracted water quantity, the share in  the
     costs of each enterprise is calculated as above. The city entered  into a contract
     for the calculated share in the costs with each enterprise.
 b.  J urisdiction o f property
     It is feared that the maintenance of the property of the collective pretreatment
     facilities by 61 associated enterprises in cooperation will cause dispute or other
                                          579

-------
    troubles on  management relating to the property in  the  future. Therefore, it
    has been decided that  the property of the facilities belongs to Yokohama city
    and it is to be maintained by the city for the purpose of its smooth maintenance
    and operation.
 c.  Sanctions against nonfulfillment of the contract
    Against  delay in payment  of shares in the construction  costs by  enterprises,
    payments not exceeding an annual rate of 14.6  percent shall be made.
 d.  Contract of bearing of the maintenance costs
    Although the contract of bearing of the construction costs has been made on the
    premise that it is followed by the contract of the maintenance and operation of
    the facilities after the  completion of construction, the latter contract will  be
    drawn up separately.
    Further, against  enterprises that have no  prospect of paying their share of the
    construction costs, it is possible to buy  back their land based on  the sales con-
    tract of land.

4.2.4   Maintenance and operation costs
    All the maintenance and operation costs of the collective pretreatment facilities
should be borne by the associated enterprises, and their allotment will be determined
by  total  load amount taking account of water  quality. Table 25 shows  the value
inferred by  types of  wastewater  and by types of  industry of the maintenance and
operation  costs per one cubic meter of treated water.
                    Table 25.  Maintenance and operation cost
By Types of Wastewater

Treatment
Unit Price
(Yen/ m3)
High Con-
centration
Cyanide
Wastewater
50,000
Low Con-
centration
Cyanide
Wastewater
900
Chromic
Wastewater
3,000
Acid/ Alkali
Wastewater
700
Printing/
Dyeing
Wastewater
300
By Types of Industry
Plating
Industry
1,200
Pickling
Industry
700
Printing/
Dyeing
Industry
300
5.   Maintenance and Operation System
5.1  Limitation prohibition and obligations of associated enterprises
     It  has  been decided that the collective pretreatment  facilities shall belong to
Yokohama city as mentioned above. Their property falls under the jurisdiction of the
economic bureau,  and the sewerage works bureau operates the facilities on a com-
mission basis.
     Between  the  city and removing enterprises, private contracts of the use of the
collective pretreatment facilities are entered into. Although the  effluent from the
facilities is controlled  by the sewerage law, wastewater from each enterprise is not
directly  controlled by the  law. Therefore, it is feared  that  the responsibility of
enterprises are not distinct, and at the same time the collective pretreatment facilities
cannot be properly maintained and operated, so that clauses of limitation, prohibition
and obligations of each enterprise are prescribed in the said contracts.
                                      580

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 a.  Limitations
     (r> The limitation of wastewater quantity and its concentration
        The daily maximum wastewater quantity and maximum concentration are
        limited so that the collective pretreatment facilities is not overloaded.
     (2) The limitation of chemicals used in working processes
        Of chemicals used in working processes, those which may obstruct the pre-
        treatment (for example, EDTA, rochelle salt, etc.) are limited in use quantity.

 b.  Prohibition
     CD The prohibition of discharging wastewater that cannot  be treated by the
        collective pretreatment; wastewater containing phenols, cadmium, mercury,
        and oils, etc. is not permitted  to be discharged.
     (D Wastewater that is in danger of damaging the facilities; wastewater contain-
        ing gasoline which will  cause fire,  and  containing mud and sand which will
        cause the blockade of sewers,  and hot wastewater.
 c.  Obligations
     CD The job of installing flowmeters
        Integral  flow  meters  are  installed  in the factory sites to  check industrial
        wastewater volume discharged.
     (2) The work of constructing monitoring pits
        Monitoring pits  for sampling of industrial  wastewater are  installed on the
        factory sites.
     (3) The task of maintaining  flow meters and monitoring pits
     ® The task of measuring the water quality
        The water quality of industrial wastewater is periodically analyzed.

5.2  Monitoring by the city
     Monitoring methods are as follows.
 a.  Monitoring of the quantity of wastewater
     By flow meters installed by types of wastewater on the site of facotries, waste-
     water is always monitored whether the  quantity is under the contracted quantity
     or not.
 b.  Monitoring of the concentration of wastewater
     On the site  of factories are installed  monitoring inlets, into which the waste-
     water of the city goes and from which the wastewater at all times is samples and
     analyzed to monitor whether  its  concentration is under the contracted concent-
     ration or not.
 c.  Monitoring of factories
     For monitoring of factories as with the monitoring of general  industrial premises
     in the city, enterprises are ordered to present a written application describing the
     content of  work, chemicals to  be used,  registered facilities,  and discharging
     methods, etc. for approval by the city. For the routine inspection of factories, it
     is a policy to monitor factories  by placing emphasis on  the type of factories
     requiring high frequency of monitoring.
                                       581

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6.   Conclusion
     This enterprising project is not designed on the same lines as established regard-
ing previous measures to cope with industrial wastewater, but aims at progressive and
permanent  measures to cope with industrial wastewater while putting forward the
"town building of Yokohama" toward the 21st century.
     The characteristics of the project are as follows.
 a.  The aspect of preventive measures
     © Although Kanazawa industrial  wastewater collective pretreatment facilities
        have been planned as a measure  to cope with wastewater of minor enter-
        prises  as  in the case of  Torihama  industrial wastewater treatment plant,
        Torihama plant were planned with the object of enterprises that had arbit-
        rarily gone into the reclaimed  land, whereas Kanazawa facilities have been
        planned as a permanent measure to cope with industrial wastewater involving
        minor enterprises that are scattered in the city, and which are to be removed
        immediately or in the future.
     (2) The city authorities decide on the locations of factories based on the nature
        of their wastewater.
     (D In place of the conventional method that relies on money being collected in
        advance from  object enterprises as the source of revenue, Kanazawa facilities
        are financed  directly by the city authorities, through funds made  available
        by the Environmental Pollution Control Service Corporation.
     © For bringing up minor enterprises, cooperation of enterprises going into the
        reclaimed land was recommended with the aim of advancing factory facilities
        and effective utilization of sites.
 b.  The aspect of facilities
     (T) Kanazawa facilities have adopted a  method to  divide the  cyanic into  high
        and low  concentration cyanic line, and the  chromic  wastewater into  a
        chromic line and acid/alkali line  including sludge treating process to treat
        them separately.
     ® The automatic control system  has now reached the almost fully automatic
        state.
 c.  Other items
     © Although sewers were laid under public roads in Torihama area,  considering
        maintenance and inspection, coping with failures, and connection of lateral
        sewers, etc.,  sewers were laid in exclusive  sites for  wastewater  pipes  in
        Kanazawa facilities, and a box-culvert method was adopted in  the plating
        industry which required four wastewater pipes.
     ® Although the  wastewater quantity of each factory was determined  based on
        the quantity of city water  used at Torihama,  the  actual discharged waste-
        water quantity was confirmed by a flowmeter installed  at the exit of waste-
        water for that purpose at  Kanazawa. Monitoring inlets were also  installed to
        make it possible to check the water quality at any time.
                                    582

-------
Acknowledgement
    The sewerage  works bureau established a working  group  conducted by Mr.'
Yoshio Tanaka, the manager of Maintenance and Operation Dept., to make a plan of
the project, and to put it into practice.
    The author  would record here the warmest acknowledgements to Mr. Sakuji
Yoshida, Mr.  Shigeyuki Suzuki,  Mr. Kokichi Machii, Mr. Toshiaki Hiramoto and
other members of the working group.
                                   583

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-------
                                US/JAPAN Conference

                                       on

                             Sewage Treatment Technology
                            WJHP-JS-15, OCTOBER,1981
       AGRICULTURAL USE
                    OF
         SEWAGE SLUDGE
                  OCTOBER 1981

                WASHINGTON, D. C.
The work  described in this paper was not funded by the
U.S. Environmental Protection Agency.  The contents do
not necessarily reflect the views of the Agency and no
official  endorsement should be inferred.
      Kazuhiro Tanaka

      Section Chief,

      Research and Technology Development Division

      Japan Sewage Works Agency
                    585

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                 PART I  BEHAVIOR OF HEAVY METALS IN SOIL AND
                         THEIR UPTAKE BY PLANTS
1.    PURPOSE
          In agricultural use of sewage sludge,  one of the important areas
     of study is the behavior of heavy metals in the soil and their uptake
     by plants when sewage sludge has been utilized for agriculture.   The
     plants growing in the soil where sewage sludge has been used,  absorb
     soil- and sludge- born heavy metals into their leaves and stems.
          Accordingly, in order to clarify which of these two types of heavy
     metals is absorbed by plants, experiments have been conducted  using
     synthetic sludge including heavy metals tagged with radioactive isotopes
     k^zn and l^Cd.  The main purpose of the experiments is to investigate
     the following two subjects:

     (1)   Uptake of added heavy metals by barley.

     (2)   Relationship between the added heavy metals and their uptake by
          barley.
                                     586

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2.   MATERIALS AND METHOD
 2.1  Preparation of Synthetic Sludges
            ^Zn -    Cd double tagged synthetic sludges were prepared in the
      same manner as in the previous report
                                           (1)
using a batch type activated
      sludge process.   At the same time,  non-tagged sludges having small
      amounts of heavy metals were also prepared.   The culture medium used
      for preparing the synthetic sludges was a glutamine culture medium.
           The glutamine culture medium was composed of 15 g of glutamic
      acid, 15 g of glucose,  5 g of ammonium chloride, 0.7 g of calcium
      chloride, 0.5 g of magnesium sulphate, 0.7 g of potassium chloride,
      1.1 g of potassium dihydrogenphosphate, 2.9  g of sodium hydrogen-
      phosphate (dodehydrate)  and 0.1 g ferric chloride (hexahydrate).  The
      above culture medium was regarded as one unit, and 1-1.5 units of
      the medium were added per day for cultivation.
           For double tagged  synthetic sludges, two types having low and
      high concentrations of  heavy metals were prepared, and their concentra-
      tions and radioactivities are shown in Table 1-1.

             Table 1-1  Heavy metal concentrations and radioactivites
                        in tagged synthetic sludges
Type of sludge
prepared
Low- concentration
sludge (L)
High- concentration
sludge (H)
Zinc
(per gram-Sludge)
ygZn
1252.4
2462.1
65Zn cpm
1,840 x 10s
1,572 x 10 5
Cadmium
(per gram-Sludge)
ygCd
6.40
10.65
109Cd cpm
1,408 x 10s
1,342 x 10s
           Further,  a non-tagged low-concentration sludge was also prepared,
      and its heavy  metal concentrations were 0.82ygCd/g-Sludge and 5.51ugZn/
      g-Sludge respectively.
                                     587

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2.2  Preparation of Tracer Heavy Metal Solutions

          The solutions containing heavy metals as tracers were prepared by
     dissolving metallic chlorides having heavy metals equivalent to 4.25
     times the concentration of heavy metals in the sludge shown in Table
     1-1 and by adding O.lmCi of 65Zn and O.lmCi of 109Cd to the solution.
     1 ml of this solution contains the same amount of heavy metals as are
     in the sludge when 0.5% of sludge based on 850 g of air-dried soil
     (=4.25 g of sludge) is added to the soil.  Two types of tracer heavy
     metal solutions having high and low concentrations were prepared, and
     their heavy metal concentrations and radioactivities are shown in
     Table 1-2.

            Table 1-2  Heavy metal concentrations and radioactivities
                       in tracer heavy metal solutions
Type of solution
prepared
Low-concentration
solution
High-concentration
solution
Zinc
(1 ml)
pgZn
5,322.7
10,464.0
Zn cpm
6,395 x 105
5,891 x 105
Cadmium
(1 ml)
ygCd
27.2
45.3
109Cd cpm
4,474 x 105
4,259 x 105
2.3  Preparation Tracer Heavy Metal-absorbed Sludge

          To 4.25 g of non-tagged sludge was added 1 m& of tracer-heavy
     metal solution prepared in 2.2, and it was mixed throughly, then,
     air-dried  for two days.

2.4  Soil

          The soil used for this investigation was a fine air-dried  soil  of
     Tanashi volcanic surface soil, which was of the same kind  as  in  the
     previous report'-'-'.  The total cadmium and zinc contents were 0.39
     Ug/g-Soil  and 1.05 ug/g-Soil respectively.
                                     588

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2.5  Method
          850 g of the air-dried soil was sampled,  and the tagged synthetic
     sludge,  tracer heavy metal-absorbed sludge or  tracer-heavy metal
     solution was added and thoroughly mixed.   After that, the  water content
     of the sampled soil was adjusted to make  it up to about 60% of its
     maximum water content, and it was transferred  to a pot for three months
     of incubation without adding any plants.   The  temperatures employed
     were 25°C during the day and 20°C during  the night (day -  12 hrs;
     night -  12 hrs), and the water content of the  soil was adjusted every
     2-3 days.   The method of adding tracer heavy metals to the soil is
     shown in Table 1-3.
          In  this soil, 20 grains of barley were sown and cultivated for
     4 weeks  under the same conditions as those of  the incubation.   After
     cultivation, the barley plants were cut down and their roots were
     removed  from the soil, then, 50 g of air-dried soil was sampled.
          Next, three months after the completion of the first  cultivation
     test, exactly the same cultivation test for barley was conducted again.

                Table 1-3  Method of adding tracer  heavy metals
Added heavy metals
or sludge
Heavy metal
concentration
Low concentration

-------
2.6  Extraction of Tracer Heavy Metals from Soil

          From the soil samples collected after the completion of each
     cultivation test, heavy metals were extracted by the following three
     methods, and the radioactivities of ^Zn and    Cd in the extracts
     were measured.

     (1)  DTPA extraction
               20 m£ of mixed solution of 0.005M DTPA (Diethylenetriarrr ne-
          pentaacetic acid), 0.01M CaCl2 and O.lM TEA (Tetraethyleneamine)
          (pH 7.3) was added to 10 g of air-dried soil, which was shaken
          for 2 hours.

     (2)  Extraction with 0.1 N hydrochloric acid
               50 mS, of 0.1 N HC1 solution was added to 10 g of air-dried
          soil, which was shaken for 1 hour.

     (3)  Extraction with 1.0 N nitric acid
               50 m£ of 1.0 N HN03 solution was added to 5 g of air-dried
          soil, which was shaken for 2 hours.

2.7  Determination of Radioactivity and Heavy Metals in Leaves and Stems
     of Barley

          To determine the radioactivity in the leaves and stems of barley,
     the sample was air-dried, put into a measuring tube as it was, and
     measured by the autowell gamma system.  For the determination of heavy
     metals, the sample was dissolved by the wet method, then heavy metals
     extracted with 0.05 M acetic acid buffer  (pH 4.5), and measured by a
     trace-metal analyzer equipped with dropping mercury electrode.  The
     added heavy metals contents of the leaves and stems were determined
     by dividing the radioactivity in the leaves and stems by the
     specific radioactivity of the added heavy metals.
                                   590

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3.    RESULTS AND DISCUSSION

 3.1  Uptake of Added Heavy Metals by Barley

           The cadmium concentration in the leaves and stems of barley is
      shown in Fig.  1-1.   In the first experiment, the concentration of
      cadmium in the leaves and stems of barley was almost constant except
      that it was higher in the experiment sections which contained 0.5% of
      sludge (L) of Section I and also in the sections which contained 1.0%
      of sludge (L)  of Section Is.  In the second experiment, the cadmium
      concentration of the leaves and stems of barley was different in each
      section from the first experiment, and the cadmium concentration had
      a tendency to be somewhat higher in large quantity-added sections
      regardless of the addition method.  This tendency was especially
      marked in Section I and Section Is.
           Fig. 1-2 shows the relationship between the added cadmium concen-
      tration in the leaves and stems and the added amount of cadmium.
           In both the first and second experiments, the added cadmium
      concentration in the leaves and stems increased almost proportionately
      to the concentration of added cadmium.  No marked difference due to
      the addition method was found, but in Section Sc, there was a tendency
      for the concentration to become somewhat higher, compared with that
      of other sections.
           Fig. 1-3 shows the proportion of added cadmium-concentration to
      the total cadmium in the leaves and stems.  Except in the sections
      where 0.5% of sludge (H) of Section Si was added, the proportion of
      added cadmium concentration was high in Section Si, which agrees with
      the tendency found in the extraction of added cadmium.
           Fig. 1-4 shows the zinc concentration in the leaves and stems of
      barley.
           In both the first and second experiments, the zinc concentration
      in the leaves and stems was apt to increase slightly when the amount
      of added zinc was increased, but no marked difference was found in any
      of the experimental sections.
           The uptake of added zinc  (Fig. 1-5) increased almost in propor-
      tion to the amount of zinc added  in the same manner as for cadmium,
      but a marked difference due to the addition method was found in this
      case.  The added zinc concentration in the  leaves and stems was highest
      in Section Sc, and it was 2-3 times that of Section Si where the
                                     591

-------
concentration was lowest.  This tendency almost agreed with that of
the extraction of added zinc.  The main reason why the added zinc
concentration in the leaves and stems was lowest in Section Si was
considered to be the state of zinc present in the synthetic sludge.
     The proportion of added zinc concentration in the leaves and
steins in shown in Fig.  1-6, and the proportion was remarkably high in
Section Sc.  For example, if we compare Section Sc and Section Si in
1.0% Section SH» their proportions were 54.0% and 21.7% respectively
in the first experiment and 49.1% and 20.1% in the second experiment.
In either case, the result in Section Sc was about 2.5 times that in
Section Si.
                                592

-------
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     10.0
      8.0
      6.0
     4.0
     2.0
             1st Exp
     12.0
     10.0
      8.0
      6.0
      4.0
      2.0
             2nd Exp
                         5.0
                          SH 0.5
                         5.0
                                        10.0
                                        10.0
                  Added  Cd concentration

                   (10~6  g Cd/g-dried soil)
        Fig. 1-2  Added cadmium concentration

                  in  leaves and steins  of barley
                        594

-------
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    50
    40
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20
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    50I   2nd  Exp
40
     30
     20
     10
                      SH
                      5.0
                          SL 1.0
                SL 0.5
                      5.0
                                          1.0
                                 10.0
                                 10.0
                Added Cd concentration

               (10~8 g Cd/g-dried  soil)
      Fig.  1-3  Proportion of added  cadmium

                in leaves and stems  of barley
                     595

-------
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    2.0
    1-0
         1st Exp.
                      1.0
                                  2.0
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1.0
     2nd Exp.
                      1.0
                                  2.0
                 Added  Zn  concentration

                 (10~5 g Zn/g-dried soil)
       Fig.  1-4   Zinc concentration in  leaves

                  and stems of barley
                         596

-------
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 8
          1st Exp.
       2nd Exp.
                  1.0
                       1.0
                                   2.0
                                       2.0
                Added  Zn  concentration

                (10~5 g Zn/g-dried soil)
      Fig.  1-5  Added  zinc concentration in

                leaves and steins of barley
                          597

-------
10
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    60
    50
    40
    30
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50
    40
    30
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    10
          2nd Exp
                     1.0
                       SL
                      1.0
                                 2.0
                                     2.0
                                               r H
                Added Zn concentration
               (10~5 g Zn/g-dried soil)
     Fig. 1-6   Proportion  of added zinc concentration
                in  leaves and stems of barley
                         598

-------
3.2  Relationship between Added Heavy Metals and their Uptake by Barley
          Tables 1-4 (cadmium)  and 1-5 (zinc)  show the correlation between
     the extracted amounts of added heavy metals and their concentrations
     in the leaves and stems of barley.   The correlation was remarkable
     regardless of addition or extraction methods, and even when Section Sc
     and Section Si were combined, a high correlation was found between
     these two factors.

               Table 1-4  Correlation between added cadmium
                          and its uptake by barley

                           Correlation coefficient


1st Exp.


2nd Exp.

Extraction
method
DTPO
HC1
HNO
DTPO
HC1
HN03
Sc
0.995
1.000
0.998
0.995
0.993
0.996
Si
0.965
0.985
0.997
0.993
0.983
0.988
Sc + Si
0.959
0.982
0.988
0.983
0.974
0.980
               Table 1-5  Correlation between added zinc
                          and its uptake by barley
                            Correlation coefficient


1st Exp.


2nd Exp.

Extraction
method
DTPO
HCl
HNO3
DTPO
HCl
HNO3
Sc
0.967
0.998
0.998
0.998
0.999
0.999
Si
0.954
0.962
0.959
0.978
0.989
0.995
Sc + Si
0.960
0.960
0.971
0.992
0.992
0.990
                                    599

-------
     The marked correlation between the extracted amount of added
heavy metals and their concentration in the leaves and stems suggests
that added heavy metals reached an equilibrium with the soil-born heavy
metals in the soil.  In the case of their extraction with 1 N nitiric
acid, the remarkable correlation also suggests that equilibrium was
established to a certain degree even in the insoluble portion.
     Further, it is assumed that these equilibria greatly depend upon
the addition method or addition morphology of heavy metals, as well as
the added amount of heavy metals.  It seems that the heavy metals in
sludge (Section Sc) established equilibria with soil-born heavy metals
which were more soluble than those in the form of inorganic matter
(Sections Si, I & Is).  Therefore, the added heavy metals were more
readily absorbed by barley in Section Sc than in other sections.
     Furthermore, the results of this investigation suggest that the
heavy metals in sludge were firmly combined with organic substances
in the sludge even in the soil over a considerable period of time.
                                 600

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4.    CONCLUSIONS

     (1)   The heavy metals in sludge, compared with those added in the form
          of inorganic matter, were present in the soil in such a state that
          they were readily extracted by any extraction method.  This
          tendency was especially remarkable for zinc.

     (2)   The added cadmium concentration in the leaves and stems of barley
          was almost proportional to the concentration of added cadmium.
          In the case of zinc concentration, there was little difference in
          any of the experimental sections.

     (3)   In this investigation,  it has become apparent that the heavy metals
          in sludge present in the soil combine firmly with organic sub-
          stances in sludge over  a considerable period of time.
     Reference

     K.  Tanaka,  T.  Mori and A.  Narita,  "Agricultural Use of Sewage Sludge"
     Progress Report (II),  US/JAPAN JOINT RESEARCH PROJECT (Japanese Side),
     US/JAPAN Conference on Sewage Treatment Technology.
                                     601

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              PART II  COMPOSTING OF DEWATERED RAW CAKES PREPARED
                       BY USE OF ORGANIC COAGULANTS
1.    RECENT STATUS OF COMPOSTING TECHNIQUE IN JAPAN

          In Japan,  a sludge composting technique has been rapidly developed
     since 1975 as a means of utilizing sludge for greens and farming lands.
     Composting is defined as the sludge treatment technology for decomposing
     or making inorganic the organic substances in sludge by using micro-
     organisms under aerobic conditions.  Therefore the organic substances
     in sludge are stabilized, and become sanitary and easy to handle and
     store.  No ill effect is given to the plants growing in the soil
     where composted sludge has been used.
          As of January 31, 1981, the composting process has been adopted in
     three municipalities, Tendo City  (5 ton/day) , Yamagata City  (.15 ton/day)
     and Tokyo (8 ton/day).  If the annual working efficiency of the process
     is 300 days, the compost output is estimated at about 2,500 ton.
     Further, the local municipalites scheduled to set up the composting
     facilities during fiscal year 1981 include Akita City (40 ton/day),
     Hitachi City (20 ton/day), Nozawaonsen-mura  (8 ton/day), Chino City
     (6 ton/day), Tokorozawa City (20 ton/day) and Kagoshima City (150 ton/
     day,  operation scheduled to be started during fiscal year 1981).  There-
     fore, compost output of about 25,000 ton is estimated at the end of
     fiscal year 1982.
          Recently, the composting technique is used as not only the sludge
     treatment process for agricultural use but also as the sludge drying
     or aerobic stabilization process.
                                      602

-------
2.    PURPOSE
          In the case of composting dewatered cakes  containing inorganic
     coagulants such as slaked lime and ferric chloride,  the recycling
     composting system in which a part of the composted product is sent back
     to the head of the fermentor as an adjusting material,  has already been
     put into practice in Tokyo, Yamagata City,  and  Kagoshima City.   The
     composting of dewatered cakes including organic coagulants (hereinafter
     referred to as "dewatered raw-cakes")  is a composting system in which
     coarse organic substances such as paddy straw,  chaff, sawdust,  and bark
     are added to the cakes mainly to improve their  physical properties
     (adjustment of water content, improvement in breathability).   This
     system has been put into practice in Tendo city.
          However, in order to adopt a composting technique in which coarse
     organic substances are added to the dewatered raw cakes, the facilities
     should be located in areas where the adding materials are abundant and
     in constant supply throughout the year.   Such coarse organic substances
     were previously disposed of as waste,  but due to the recent advancement
     in re-use technology, they are now being re-used as  fodder,  material
     for underdraining, fuel, and for the cultivation of  mushrooms,  and have
     therefore become more expensive.
          The composting of dewatered raw cakes using polymer will meet
     serious future situations such as shortages in  coarse organic sub-
     stances and the consequent rise of composting cost.   A method of compost-
     ing dewatered raw cakes which does not require  the addition of any coarse
     organic matters is essential, however.
          This paper describes the feasibility of such a  technique.
                                      603

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3.   EXPERIMENTAL APPARATUS AND METHOD

 3.1  Apparatus

           Experiments have been  conducted using horizontal  scoop type
      experimental composting apparatus  (fermentation  capacity:  4 ton/day).
      The schematics of the primary  fermenting apparatus  and secondary
      fermenting house are shown  in  Fig.  2-1.   The  main instruments  include
      a mixer,  gyle, turner, hopper,  vibrating sieve,  meter, and control
      board.   The specification of each  instrument  is  shown  in Table 2-1.

 3.2  Method

 3.2.1  Preparation of Return Compost

              In order to  compost dewatered raw cakes  without addition  of
         coarse organic matter, it is necessary to  prepare return compost
         to be  used for the adjustment of the  water content  of dewatered
         raw  cakes.   In this experiment,  as the first  step,  dewatered raw
         cakes  were mixed  with dry digested cakes including  polymer  (herein-
         after  referred to as "dry digested cakes")  to adjust the water
         content of the cakes,  then they  were  aerobically composted.
                                   604

-------
O
O1
                                             Flowmeter
                                                              Dewatered cake &
                                                              return compost-
                                                              feed conveyor
                                                             Air blower,
                                                                               o
                  Conveyor
                                Return
                                compos t
                                hopper
                                                                               Mixer
                                                                      |  Return control board
                                                                     Automatic measuring device
                                                                    -— Vibrating seive
Conveyor (4)
                                Mixer control
                                board

                                Net type air
                                diffuser plate
               Entrance
                                 Secondary fermenting house
                        Fig.  2-1  Schematics of primary fermenting apparatus
                                  and secondary fermenting house

-------
             Table  2-1   Specification of  major  instruments
(1)   Mixer
                Mixing batch capacity
                Mixture geared motor
                Discharge geared motor
                Discharge capacity

                Power supply
0.25 m3
2.2 kW • 4P

0.4 kW • 4P

100 kg/min
200 V
(2)   Gyle
                Size

                Capacity


                Retention time

                Pile height
                Turner
10,900mm x 2,000mm x 1,600mm
                       high
About 4 ton/day (wet)
1.5 ton/day  (dry)
About 7 days

1.0 - 1.2 m
Number of turns 3/min,
Travel 30cm/min
(3)   Aeration
     device
                Blower capacity

                Diffuser plate



                Diffuser pipe

                Flowmeter
4 m /min, l.,OOOmmAq,
Motor 1 kW
2,000mm x 2,000mm x
2,000mm high, 2 steel
diffuser plates

0 50 mm, VC x 3 pipes

800 £/min 2 F-meters
400 £/min 3 F-meters
Air volume adjustable by
valve
(4)   Monitoring
     device
                Temperature
6 thermostats,
Recorder  (6 pointer type)
(5)   Take-out and
     return device
                Conveyor
                Compost hopper
                Screw feeder


                Vibrating seive
                     Automatic measuring
                     device
0.75 kW
2 m3
3 varying speed 4, 11,
15 kg-wet/min
Max. capacity 15 kg-wet/min
Steel net plate (10, 20  &
                     30  mm)

Max. 600 kg/hr
                     Size
(6)
Secondary
fermenting
house
                     Pile height
Vinyl house, 20,000mm x
7,000mm x 2,000mm high,
Entrance through which 2-
ton vehicle is able to
get in

1 - 2 m
                                 606

-------
            As the second step,  the compost prepared in the first step was
       mixed with dewatered raw  cakes,  then aerobically composted.   This
       procedure was repeated several times to obtain return compost with
       a constant quality.

3.2.2  Properties of Test Materials

            The properties of test materials,  dewatered cakes,  dry digested
       cakes, return compost and feed mixture,  are  shown in Table 2-2.
       Dewatered raw cakes were  prepared by adding  about 1%/dried sludge
       of polymer coagulant to the mixture  of  primary sludge and excess
       activated sludge,  and by  dewatering  it  by centrifuge.  Its  properties
       are as follows:  Moisture content 81 -  83%,  pH 5.3 - 5.7,  ignition
       loss 83 - 87%,  and BOD 310 - 390 mg-O2/g-DS.   Thus,  it has a high
       moisture content and,  at  the same time,  has  a large  amount of
       easily-biodegradable organic matters.
            As for dry digested  cakes,  the  mixture  of primary sludge and
       excess activated sludge was digested anaerobically at 37°C for
       about 30 days.  After elutriation it was dewatered by a  belt press
       filter using a  polymer coagulant and heat-dried with an  air  dryer.
       Its properties  are:   Moisture content 15 - 30%,  pH 7.0 - 7.3,
       ignition loss 42 - 46%, and BOD  47 - 63  mg-O2/g-DS.   Both its
       moisture content and the  content of  easily-biodegradable organic
       matters are  low.
            The properties  of stable return compost are:  Moisture
       content 32 -  37%,  pH 7.9  - 8.2,  and  BOD  23 -  33 mg-O2/g-DS.   The
       BOD is markedly low,  so that aerobical  composting is considered  to
       have been completed.
            The properties  of the feed  mixture  of the dewatered raw cakes
       and the return  compost are:   Moisture content 41 - 56%,  pH 7.2 -
       7.8,  and BOD  46 -  81 mg-O2/g-DS.
                                     607

-------
                                             Table 2-2  Properties of test materials
"^
Material
Dewatered
raw cake
Dried digested
cake
Return compost
Feed mixture
Item
Tin i +-""""""--*

Range
Average
Range
Average
Range
Average
Range
Average
Moisture
content
%
81-83
81.8
15-30
21.2
32-27
34.8
41-56
48.7
PH

5.3-5.7
5.57
7.0-7.3
7.15
7.9-8.2
8.05
7.2-7.8
7.50
Ignition
loss
%
83-87
84.5
42^16
55.0
42-44
43.3
45-51
48.3
Calorific
value
KcalAg-DS
4,500-4,900
4,719
2,300-2,500
2,436
2,360-2,390
2,384
2,400-2,700
2,596
BOD5
mg O2/g-DS
310-390
331
47-62
54.7
23-33
29.0
46-81
67.3
C
%
43-47
44.6
22-23
22.8
22-33
22.7
23-30
25.5
N
%
5.0-5.7
5.2
2.5-2.9
2.7
2-3.5
2.9
3.1-4.3
3.60
C/N

8.2-9.0
8.54
7.7-9.2
8.5
6.4-8.5
8.1
6.7-8.7
7.3
o
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-------
4.   RESULTS AND DISCUSSION

 4.1  Pre-adjustment of Feed Mixture

           In the pre-adjustment of the feed mixture,  attention must be
      paid to the initial moisture content of the mixture and its mixing
      procedure.   First of all,  when the moisture content was 55% or more
      and the pile height of the mixture was about 1 m,  lowering of its
      breathability was found due to compression  by its  own weight.   Further,
      on turning, the particle diameters of the mixture  were  increased due
      to their own cohesion so that anaerobic fermentation was found to
      occur.   However,  when the  initial moisture  content of the feed mixture
      was 50% or  less,  such a phenomenon was not  observed.  Accordingly,
      when dewatered raw cakes including polymer  alone are composted,  it is
      necessary to lower the moisture content to  50% or  less.
           The dewatered raw cakes and the return compost were mixed convec-
      tionally inside the mixer,  then discharged  with  a  double screw at the
      bottom  of the mixer.   Therefore the mixture was  liable  to form into a
      mass, and its quality was  lowered.
           In this case,  a  paddle type mixer is considered to be preferable
      since its mixing  time is short and the feed mixture is  not kneaded  in
      the  mixer.

4.2   Change  of Fermenting  Temperature and Concentrations of  Carbon  Dioxide
      and  Ammonia

  4.2.1  Fermenting Temperature

              The  change of fermenting temperature with  time  is  shown  in  the
        example  of Fig. 2-2.  The  rising rate of the  temperature at the
        initial  stage  of fermentation was 1.0 -  3.3°C/hr and the temperature
        was  rapidly  increased until  the  maximum  fermenting temperature of
        73 -  78°C was  reached in  about 40 hours.  However, after turning,
        the  fermenting temperature  tended to decrease.   It is  considered
        that  the  BOD to be decomposed  in  the fed mixture was  related  to
        this  phenomena.  The  BOD of  the  fed mixture of  the dewatered  raw
        cakes  and  the  return  compost  in  this experiment was  22  x 103  - 46
        x 103  g.O2-VTS, which was  considerably low, and about  1/3 -  1/8  of
        BOD  (65 x  103  g.O2~VTS)   of the  fed mixture of dewatered  raw cakes
                                    609

-------
 and dry digested cakes.   In the case of the mixture of dewatered
 raw cakes and dry digested cakes a high temperature of 65°C or more
 was maintained even after turning.   Therefore,  the low BOD was

 considered to result in  low total heat generation.  Accordingly,

 if the extinction of germs, weed seeds, and some others are taken
 into consideration as the purpose of composting, the BOD of the

 feed mixture is significant and a fermenting temperature of 65°C
 or more should be maintenaned for at least 48 hours.
                         1st turning
                         Fermenting
                         temperature
    30
45
60
75
90
105
120   135   150   165
                     Time  (hr)
Experiment No.
Date
Weight of feed mixture

Moisture content
Ignition loss
BOD
Aeration
               K-8
               23 January - 3 February 1981
               1,152kg(329kg of dewatered raw cakes
               + 823kg of return compost)
               48.7%
               49.6%
               78.8 mg-02/g-DS
               430 £/min  1.47 £/minAg-VTS (fed mixture)
               8.22 £/min/kg-VTS(cake)
    Fig. 2-2  Change of fermenting temperature over time
              (Horizontal scoop type fermenter)
                          610

-------
4.2.2  Concentrations of Carbon Dioxide and Ammonia Gas

            Fig.  2-3 shows the change in the concentrations of carbon
       dioxide and ammonia gas in the small size composting apparatus
       (35 I).
            The concentration of carbon dioxide was 0.4% at the start of
       the experiment, but 12 hours later it began to increase rapidly;
       24 hours later the maximum concentration of about 11% was reached,
       then decreased rapidly to 0.5% 48 hours after the start of the ex-
       periment.   After that, turning was conducted, but almost no further
       carbon dioxide was generated.   This tendency was also found in other
       experiments.    As for the concentration of ammonia, the ammonia gas
       began to generate rapidly when the maximum concentration of carbon
       dioxide had been reached, and the maximum concentration of about
       8,000 ppm was reached about 36 hours after the start of the
       experiment.  After that, it decreased with the time and fell to
       2,500 ppm 45 hours after the start of the experiment.
                                    611

-------
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S-43  8.82  Vmin/kg-VTS
S-44  5.67
S-45  4.23

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                              Time  (hr)
                                                        80    90
             Fig.  2-3  Change of concentrations of  carbon
                       dioxide and ammonia gas   (1/2)
                                   612

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4.2.3  Discussion of Aeration

            The initial aeration rate in the horizontal scoop type compost-
       ing experiment was set at 8 - 13 £/min/kg-VTS(cake)  in order to
       obtain the optimum temperature-rising rate of 1 - 3°c/hr which was
       found in the preliminary experiment in the small size fermentor.
       As a result, aerobic composting proceeded favorably.   This experi-
       ment was performed at an average daytime temperature of 0 - 5°C
       in the winter.  As for summer season, the microorganism activity
       is increased due to higher temperature so that higher aeration rate
       would be required.
            Since there is a tendency for aerobic composting to complete
       rapidly within about 10 days, it is considered that the aeration
       rate after about 10 days of operation can be reduced depending upon
       the fermenting temperature.

4.2.4  BOD Removal Rate

            The cumulative BOD removal rate with the change of fed mixture
       is shown in Fig. 2-4.  On the 5th day after the start of composting,
       a high BOD removal rate of 50 - 80% was observed, but after
       that, almost no change in BOD removal rate was found.  On the
       contrary, the BOD removal rate in composting the chaff-added
       mixture that had been studied until last year was about 10% on the
       5th day after the start of composting, and was remarkably low in
       comparison with that of non-added compost.
                                   614

-------
                                                                   BOD removal rate  (%)
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               «ft
               ^ (D

               ° +

               D. H
               p, 
               H- ft
               ft C


               S3
               0)
                                                                                                   X XX

                                                                                                   oo

-------
4.2.5  Change in Physical and Chemical Properties of Misture

       (a)   Change of moisture content
                 The change of moisture content over time is shown in
            Fig. 2-5.  The initial moisture content (about 50%)  of the fed
            mixture was rapidly lowered during the early fermenting stage,
            and it became 7 - 15% lower than the initial moisture content
            5 days later.  Then, it fell to 39 - 43%,  and on the 30th day
            when aerobic composting was completed, it further decreased to
            30 - 36%.  Therefore, the mixture became easy to handle and
            could be used as water-content adjusting material for return
            compost.

       (b)   Change of pH
                 The change of pH is shown in Fig. 2-6.   Teh fed dewatered-
            raw cakes showed a weak acidity of 5.3 - 5.7; return compost,
            a weak alkalinity of 7.9 - 8.2; and the mixture, a neutrality
            of 7.2 - 7.8.  The pH of the fed mixture,  for which fermenta-
            tion was started around neutrality, indicated the weak alkali-
            nity of 8.0 - 8.5 on the 5th day after the start of fermenta-
            tion, but after that, its pH was lowered little even when the
            secondary fermentation proceeded.

       (c)   Change of BOD
                 The change of BOD with the elapse of days is shown in
            Fig. 2-7.  The BOD's of the dewatered raw cakes, the return
            compost and the fed mixture were 310 - 390 mg O2/g-DS, 23 - 33
            mg O2/g-DS, and 46 - 81 mg O2/g-DS, respectively.  Depending on
            the properties of dewatered cakes or the mixing ratio of
            return compost, the BOD value of the fed mixture varied, but
            it  rapidly fell  to  20  -  30 mg  02/g-DS on  the 5th day  after
            the start of the primary fermentation, then it had a tendency
            to attain a constant value.  The BOD after the primary
            fermentation was considerably low and about 1/2 or less of
            the BOD  (45 - 70 mg 02/g-DS) of the dewatered digested cakes
            including polymer and chaff-added mixture.  This means the
            easily-biodegradable organic metters were considerably decom-
            posed and the mixture was stabilized.
                                   616

-------
<*>
  30  -
                                                                   No.
                                                                   K-2
                                                               -O- K-5
                                                               -•- K-6
                                                               -*• K-8
          5    10        20         30
                              Days
50
60
                 Fig. 2-5  Change of moisture content
                                     617

-------
                                                                No.
05     10    15   20          30




                        Days
50
60
                       Fig. 2-6  Change of pH
                                 618

-------
100.
         (d)  Change of ignition loss
                  The change of ignition loss with the elapse of days is
             shown in Fig. 2-8.  The ignition loss of the dewatered raw
             cakes, the return compost and the fed mixture were 83 - 87%,
             42 - 44%, and 46 - 51%, respectively.  Since they were rapidly
             decomposed during the 5 days of the primary fermentation
             period, the ignition loss decreased remarkably by 5 - 7% of
             the initial value, then decreased gradually.  The decomposition
             rate of organic substances was about 7-9 kg/day until the 5th
             day after the start of composting, and then 1-2 kg/day.
                           Days
                                      30
                                 Fig.  2-7  Change of BOD
50
60
                                   619

-------
  52
  50
  48
  46 ^
-2 44
  42
  40
     T
                                  No.

                                 K-2
                                 K-5
                                 K-6
                                 K-8
                10
15   20
                                     30
                                                          50
                                                60
                              Days
                  Fig. 2-8  Change of ignition  loss
                                      620

-------
       (e)   Fertilizer ingredients
                 The fertilizer ingredients of the composted dewatered raw
            cakes are shown in Table 2-3.   The compost contains 3.4% total
            nitrogens, 3.7% phosphoric acid and 0.6% potassium, and both
            total nitrogen and phosphoric acid contents are characteristi-
            cally about two times those in the chaff compost made of de-
            watered digested cakes.

                    Table 2-3  Fertilizer ingredients
\ Item
\
Experi- \
ment No. \
K-5
K-8
Dewatered
digested
cake-chaff
Days


(day)
30
30

60

Moisture
content

(%)
34.81
33.21

58.16

T-N


(%)
3.37
3.47

2.13

P205


(%)
3.65
3.71

1.34

K20


(%)
0.28
0.91

0.57

NO3-N


(ppm)
19
29

411

CaO


(%)
0.94
0.83

0.26

MgO


(%)
1.72
1.08

0.41

CEC


(me)
77.1
-

44.4

                                        (Based on the weight of dried
                                        compost except moisture content)
4.2.6  Young Plant Test of Compost

            In order to investigate the effect of compost upon the germina-
       tion and growth of rareripe, small shantung greens, a young plant
       test was conducted.  The four kinds of composts used in this test
       were:  Chaff compost made of polymer-added, dewatered digested
       cakes; sawdust compost made of polymer-added, dewatered digested
       cakes; compost made of a mixture of polymer-added dewatered raw
       cakes and polymer-added dry digested cakes; and compost of no
       additives.

       (a)   Method
                 Test soil was placed in pots and both test and control
            soils were thoroughly mixed.  The water content of the soil
            was adjusted to make it up to about 70% of the maximum water
            content.  Seeds were sown and their germination and state of
            growth were investigated.
                                     621

-------
(b)   Materials
     1)   Analysis  of test samples (%)
Test section
Compost No. 13,
(Dewatered digested cake + chaff)
Compost No. 14,
(Dewatered raw cake + dry digested
cake)
Compost No. 15,
(Dewatered digested cake + sawdust)
Compost No. 16,
(Dewatered raw cake + return compost)
Control bark compost
Water
content
48.05
23.74
59.39
32.07
65.15
T-N
1.04
2.30
0.78
2.18
0.27
T-N
(Dry based)
(1.92)
(3.01)
(1.92)
(3.21)
(0.77)
     2)   Test soil and crops

         Humus volcanic soil (Sampled at Hamadayama,  Suginami-ku,
                              Tokyo)
             Table 2-4  Test soil and crops
r»H
ptl
H20
5.60
KCH
5.05

CEC
me
28.1
Substitutive
base
CaO
12.10
MgO
0.82
K2O
0.20
Absorption
coefficient
N
859
P205
2,732
TP

%
8.25

1

0.4
Maximum water
content

103.8
Volume
weight
g
400
     Volume weight 	  Weight of dried soil per pot (500 m£)

     Rareripe,  small shantung greens       25 seeds/pot
                           622

-------
     3)  Test section and amount used
              Table 2-5  Test section and amount used
Test section
Compost No. 13
(Dewatered digested cake + chaff)
Compost No. 14
(Dewatered raw cake + dry digested
cake)
Compost No. 15
(Dewatered digested cake + sawdust)
Compost No. 16
(Dewatered raw cake + return compost)
Control bark compost
Non-added section
Amount of compost used based
on the weight of dried soil(q)
(5)
9.6
6.6
12.3
7.4
14.3
0
(10)
19.2
13.1
24.6
14.7
28.7
0
(20)
38.5
26.2
49.2
29.4
57.4
0
(40)
77.0
52.5
98.5
58.9
114.8
0
         a)   As common fertilizers, use ammonium sulfate, calcium
             superphosphate and potassium chloride containing 75 mg
             each of N,  ^2^2 an<^ ^0 respectively.
         b)   In the Non-added Section, use common fertilizers
             only.
     4)   Cultivation
         Placement of soil
         Addition of compost
         S adjustment of
         water content
         Sowing
         Investigation of
         output
January 27, 1981
January 28, 1981

January 28, 1981
February 27, 1981
(c)   Results
          The  test results  are as shown in Table 2-6.
          The  germination started two days after sowing,  and there
     were  no differences  in the germination starting day among the
     test  sections.
                                 623

-------
Table 2-6  Results of young plant  test
Test
section
Compost
No. 13
Compost
No. 14
Compost
No. 15
Compost
No. 16
Control
bark
compost
Non-
added
Amount
fed
g
5
10
20
40
5
10
20
40
5
10
20
40
5
10
20
40
5
10
20
40

Germi-
nating
force
%
94
96
94
98
96
96
94
96
98
94
96
96
96
98
96
96
94
94
96
96
98
Germi-
nation
rate
%
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
98
100
100
100
100
100
Number
leaves
2 Feb.
20.0
22.5
21.0
20.0
19.0
20.0
21.0
20.5
21.0
24.5
25.0
21.0
18.0
24.0
23.5
24.0
20.0
23.0
25.0
23.5
23.0
of seec

6 Feb.
24.5
25.0
25.0
24.0
25.0
25.0
24.0
24.0
24.5
25.0
-
24.0
25.0
24.0
25.0
24.5
25.0
25.0
-
24.5
24.5
Leaf
L
cm
9.0
10.0
10.1
8.3
8.7
9.0
8.4
5.7
10.0
9.8
7.9
6.0
9.8
8.5
6.4
5.0
9.0
10.0
9.9
10.2
9.3
W
cm
2.3
2.6
2.8
2.5
2.2
2.4
2.4
1.8
2.3
2.4
2.3
1.7
2.4
2.4
2.1
1.3
2.4
2.5
2.5
2.9
2.2
Fresh leaves
Weight
g
7.9
10.3
9.9
6.5
6.0
6.9
5.6
3.7
9.4
9.3
8.5
5.7
8.9
8.1
5.2
4.1
10.1
12.0
11.9
12.6
9.6
Index No.
g
82.3
107.3
103.1
67.7
62.5
71.9
58.3
38.5
97.9
96.9
88.5
59.4
92.7
84.4
54.2
42.7
105.2
125.0
124.0
131.2
(100.0)
                 624

-------
     As for the growth after germination, no differences  in
growth due to the amount of compost used were found in  the
control bark section, but in 4 compost sections, compared with  the
control bark compost section or non-added section, a delay in
growth was observed in proportion to increase in the amount
of compost.  This delay in growth was a little more remarkable
in Compost No.  14 & No. 16 sections than in Compost No. 13 &
15 sections.   This tendency in growth affected the output.
     This is due to the difference in the amount of ingredients
contained in the fed compost.   Table 2-7 shows the
amount of Nitrogen in the fed compost and a delay in growth
due to toxic substances was not found in this test.

      Table 2-7  Amount of fed nitrogen
Test section
Compost No. 13
(Dewatered digested cake + chaff)
Compost No. 14
(Dewatered raw cake + dry digested cake)
^'
Compost No. 15 /'
(Dewatered digested cake + sawdust)
Compost No. 16
(Dewatered raw cake + return compost)
Control bark compost
Amount (Dry based) g
(5)
100
151
96
160
39
(10)
200
301
192
320
77
(20)
399
603
384
641
155
(40)
799
1,205
768
1,282
310
                       625

-------
5.    CONCLUSIONS

          The results obtained in the experiment were as follows:

     (1)   Composting of dewatered raw cakes is successfully performed
          through the return of compost and aeration.

     (2)   It was found that the ammonia concentration in off-gas in the
          primary fermentation process (after about 10 days) was 5,000 -
          8,000 ppm maximum at an aeration rate of 5 £/min kg-VTS.

     (3)   There was a tendency for VTS and BOD to rapidly decrease and
          to be stabilized in the primary fermentation process.

          In the future, the optimum combination of the moisture content of
     return compost and that of dewatered cake to be composted will in-
     evitably be found.
                                    626

-------
                           UNITED STATES PAPERS
RECENT DEVELOPMENTS IN MECHANICAL COMPOSTING OF MUNICIPAL
SLUDGE	  629
    Atal  E. Eralp, Municipal  Environmental  Research Laboratory,
    ORD,  USEPA and Harry A. J. Hoitink, Ohio Agricultural  Research
    and Research Center, Ohio State University, Wooster, Ohio

THERMAL PROCESSES FOR CONVERSION OF SLUDGE: STATUS, EPA RESEARCH,
FUTURE DIRECTIONS	'.	  661
    Joseph B. Farrell, Municipal Environmental  Research Laboratory,
    ORD,  USEPA

TECHNOLOGY ASSESSMENT OF THE VERTICAL WELL CHEMICAL REACTOR	  681
    John  M. Smith and Jeremiah J. McCarthy, Municipal  Environmental
    Research Laboratory, ORD, USEPA

FLOW MANAGEMENT BY POROUS PAVEMENT AND INSITUFORM CONTROL OF
FILTRATION	  697
    Carl  A. Brunner, John N. English, and Richard Turkeltaub,
    Municipal Environmental Research Laboratory, ORD,  USEPA

SEQUENCING BATCH REACTORS FOR MUNICIPAL WASTEWATER TREATMENT	  721
    Edwin F. Barth, Municipal Environmental Research Laboratory,
    ORD,  USEPA

ANAEROBIC TREATMENT OF MUNICIPAL WASTEWATER	  749
    Irwin .J. Kugelman, James A. Heidman and Donald Brown,
    Municipal Environmental Research Laboratory, ORD,  USEPA

NATIONAL  SURVEY OF MUNICIPAL WASTEWATERS FOR TOXIC CHEMICALS	  773
    Jesse M. Cohen, Lewis Rossman and Sidney A. Hannah,
    Municipal Environmental Research Laboratory, ORD,  USEPA

CONTROL OF SPECIFIC ORGANIC AND METAL CONTAMINANTS BY  MUNICIPAL
WASTEWATER TREATMENT PROCESSES	  803
    Dolloff F. Bishop, Albert C. Petrasek, and Irwin J. Kugelman,
    Municipal Environmental Research Laboratory, ORD,  USEPA

AN INDUSTRIAL PERSPECTIVE ON JOINT MUNICIPAL-INDUSTRIAL WASTE-
WATER MANAGEMENT	  849
    Gerald N. McDermott, Senior Engineer,
    The Procter & Gamble Company, Cincinnati, Ohio

                                                      (continued)

                                   627

-------
                     UNITED STATES PAPERS (continued)
COST-EFFECTIVENESS AND WATER QUALITY JUSTIFICATION FOR
ADVANCED WASTEWATER TREATMENT (AWT) FACILITIES	   865
    Robert J. Foxen, Office of Water, USEPA

EFFECTS OF MULTIPLE DIGESTION ON SLUDGE	   885
    Wilbur N. Torpey, Consultant, New York, New York
    John F. Andrews, University of Houston, Texas
    James V. Basilico, Office of Research and Development,
    USEPA

RESEARCH SUPPORTED BY THE NATIONAL SCIENCE FOUNDATION RELATING
TO TREATMENT OF WASTEWATER -AND MANAGEMENT OF RESIDUAL SLUDGES	   907
    Edward H. Bryan, National Research Foundation,
    Washington, D.C.

REMOTE SENSING OF SEPTIC SYSTEM PERFORMANCE USING COLOR
INFRARED AERIAL PHOTOGRAPHY	   91 9
    David W. Hill and Rebecca B. Slack, Region, IV, USEPA
    and E. Terrance Slonecker, Environmental Photographic
    Interpretation Center, USEPA, Warrenton, Virginia

TWO-PHASE ANAEROBIC DIGESTION OF ORGANIC WASTES	   929
    Sambhunath Ghosh, Ph.D., Institute of Gas Technology,
    Chicago, Illinois
                                628

-------
RECENT DEVELOPMENTS IN MECHANICAL COMPOSTING OF MUNICIPAL SLUDGE
                               by
                         Atal E. Eralp
                  Wastewater Research Division
          Municipal Environmental Research Laboratory
              U.  S. Environmental Protection Agency
                    Cincinnati, Ohio  45268

                              and

                      Harry A. J. Hoitink
                  Department of Plant  Pathology
        Ohio Agricultural Research and Development Center
                      Ohio  State University
                      Wooster, Ohio  44691
        This paper has been reviewed 1n accordance with
        the U.S. Environmental Protection Agency's peer
        and administrative review policies and approved
        for presentation and publication.
                  Prepared for Presentation at:
               8th United States/Japan Conference
                               on
                   Sewage Treatment Technology

                          October  1981
                         Cincinnati, Ohio
                              629

-------
RECENT DEVELOPMENTS IN MECHANICAL COMPOSTING OF MUNICIPAL SLUDGE

Atal E. Eralp
Wastewater Research Division
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio

and

Harry A. J. Hoitink
Department of Plant Pathology
Ohio Agricultural Research and Development Center
Ohio State University
Wooster, Ohio
INTRODUCTION

     Sewage sludge composting is an aerobic, microbiological decay process.
Under favorable environmental conditions, microorganisms contained in the
sludge will begin to break down the large organic molecules also present in
sewage sludge.  Using the organic matter as a substrate, the microorganisms
raise their metabolic rates and hence, the surrounding temperatures. Elevated
temperatures in the compost mixture, as well as microbial antagonism are pri-
marily responsible for the elimination of pathogenic organisms.  The result-
ing material, after completion of the process, is an earthy, humus-like
material which can be used as a soil conditioner.

     Composting can effectively transform municipal organic waste into an
agriculturally and horticulturally useful product that is easy to handle and
readily accepted by the public.  Several composting methods have been ex-
tensively researched and tested, and have been found to be reliable for
stabilizing and minimizing the pathogen content in sewage sludge and septage.
The two most widely used and accepted methods of sewage sludge composting
in the United States are the static aerated pile method developed by the
U. S. Department of Agriculture at Beltsville, Maryland, and the windrow
method.

     In recent years several windrow and static pile composting systems have
replaced manual labor with automated machines in order to reduce cost and
reliability.  Several others covered their systems in order to reduce odor
and protect their systems against extreme weather conditions.

     In some European composting operations, within-vessel systems have been
developed and operated for many years.  Within-vessel composting is intended
to provide a system with operational control that is superior to that avail-
able with conventional windrow or static-pile composting techniques.  There
are additional advantages, in that: the composting sludge is sheltered from


                                   630

-------
 the environment;  land requirements  are  lower  than for  windrow or static-pile
 composting;  and surrounding areas are protected  from odor and other undesir-
 able results of open composting sites.

      Often enclosed  and mechanized  systems  are viewed  as  a black box perform-
 ing a composting  operation in a different and hopefully in an efficient way.
 This misunderstanding results in skepticism toward the system or in an un-
 reasonably high expectation of the  system.  In order to evaluate a  mechanical
 system,  it is  important to realize  that  regardless of  the degree of mechaniz-
 ation the  basics  of  the composting  are  the  same,  i.e., the process  is aerobic
 biological degradation.

      Development  of  an effective composting system follows three major steps.

      1.  Understanding of  the major feactors  affecting the composting and
 developing control strategies for optimization of  the  process.

      2.  Development  of the hardware  to  effectively  implement  the optimiza-
 tion concepts  developed in the first  step.  This  involves  the  development of
 configuration  of  the  system and all the  equipment  needed  in the  operation.

      3.  Evaluation of the developed  system.

      Although  more research is  needed for complete understanding of the com-
 posting  process,  there is  enough information  available for  private  industry
 to  develop and promote mechanical composting  systems.  About 10  mechanized
 systems, most  of  them enclosed,  are presently marketed in  the  United  States.

      During  the last  eight  years, the Ultimate Disposal Section  supported
 developments in windrow and  aerated pile composting  systems.   Recent
 projects, however, deal with  optimization of  composting and evaluation
 of  systems developed  by private  companies.  The material to be presented
 in  this  paper  is  based  on  the  two ongoing research projects cooperatively
 conducted by the  Ultimate  Disposal  Section  of the Wastewater Research
 Division, United  States Environmental Protection Agency, and a)  Dr. Melvin
 F.  Finstein,  Rutgers, The  State University  of New  Jersey, b) Dr.  Harry
 A. J. Hoitink, Ohio Agricultural Research and Development Center.

      In  the Rutgers project,  the optimization of composting using tempera-
 ture  as  a control measure is being investigated.    In the Ohio Agricultural
 Research and Development Center project, the concepts advanced at Rutgers
 are being evaluated in a highly automated enclosed system at the  facili-
 ties of Compost Systems Company in South Charleston, Ohio.

BACKGROUND (1,2)

     Major factors affecting biological  activity and, therefore  the compost-
ing process,  are:
                                    631

-------
     1.  Nutrients and their availability
     2.  Moisture content
     3.  Oxygen supply and aeration
     4.  Temperature

     Nutrients.  Generally municipal sludge includes all the necessary
nutrients for the growth of aerobic organisms although not always at the
right proportions.  An important parameter in terms of nutrients is the
Carbon:Nitrogen Ratio (C/N).  It is important because it provides a
useful indication of the probable rate of organic matter decomposition.
Microorganisms use about 30 parts of carbon for each part of nitrogen.
Thus, an initial C/N ratio of 20 to 35 would be most favorable for
rapid conversion of organic wastes into compost.  Sewage sludges usually
have C/N ratios of less than 15.  Although decomposition will be rapid
at this ratio, nitrogen may be lost as ammonia.  The addition of wood-
chips or other organic bulking materials raises the C/N ratio, ensuring
the conversion of available nitrogen into organic constituents of the
biomass.  The subsequent removal of the woodchips for reuse then lowers
the C/N ratio, allowing N to mineralize.

     Moisture Content.  Sewage sludges can be composted aerobically over
a wide range of moisture contents, 30% and higher, if aeration is adequate.
However, excessively high moisture contents should be avoided in most
aerobic composting systems, because water displaces air from the pore
spaces and can quickly lead to anaerobic conditions.  On the other hand,
if the moisture content is too low (less than 40%) stabilization will be
slowed because water is essential for microbial growth.  The most favor-
able moisture content for composting sludge (22% solids) with woodchips
by the aerated pile method is from 55 to 65% in the sludge-chip mixture.

     Oxygen Supply and Aeration.  In composting sewage sludge, aeration is
essential for the growth of thermophilic microorganisms to ensure rapid
decomposition, odor abatement, and stabilization of the residual organic
fraction which remains as compost.  Aeration also provides for lowering the
moisture content of composting materials that may have initially been too
high.  The forced aeration system used with the Aerated Pile Composting
Method provides for internal oxygen levels of from 5 to 15%.  Within this
range, maximum temperatures are attained to ensure pathogen destruction
and rapid stabilization.  Proper control of the aeration rate is essential
because too high a rate can lead to excessive heat loss, cooling of the
pile, and incomplete composting and stabilization.

     Temperature.  Temperature profoundly affects the growth and activity
of microorganisms and, consequently, determines the rate at which organic
materials are composted.  Most of the microorganisms in sewage sludge are
mesophilic; that is, they grow best in the temperature range of 20 to 35 °C.
However, as temperatures increase during composting, a specialized group of
microorganisms becomes predominant.  These are thermophilic aerobic organisms
that develop only at higher temperatures and grow fastest at 45 to 65 °C.
They generate sufficiently high temperatures to destroy human pathogens.
                                     632

-------
     In this paper the work on the correlations between temperature, aera-
tion and moisture content will be presented.  The experiments on the effects
of major nutrients, Carbon to Nitrogen ratio and alternative bulking agents
are still continuing and will be presented later.

RUTGERS EXPERIMENTS (3,4)

     In composting, a basic process control objective is to maximize micro-
bial activity at the expense of the waste being treated.  This is equiva-
lent to maximizing metabolic heat output.  To approach this objective it is
necessary to consider that, in the self-heating ecosystem, temperature is
both effect and cause.  The temperature is a function of the accumulation of
heat generated metabolically, and simultaneously the temperature is a deter-
minant of metabolic activity.  The interaction between heat output and
temperature is the centerpiece of rational control of the composting process.

     Soon after organic material is assembled into a self-insulating mass
the temperature starts to increase as metabolic heat accumulates.  At first
mesophilic growth is stimulated by the higher temperatures but, as inhibi-
tive levels are reached, this leads to a self-limiting condition.  Because
the elevated temperature now induces thermophilic growth the pattern is
repeated in a second, hotter stage.  At peak thermophilic temperatures the
metabolic activity is relatively slight.  In sum, the system is prone to
self-limit via the excessive accumulation of heat.  It has been reported
that the temperature most conducive to organic matter decomposition is
greatest at 52 to 60 °C, and that a steep decline starts above this upper
boundary.

     One of the purposes of the Rutgers study was to devise a practical
means of controlling temperature in field-scale composting, and to evaluate
such an approach to process control.

     Composting materials.  Sludge was obtained from the Camden County
Municipal Utilities Authority, Jackson Street Sewage Treatment Plant, Camden,
New Jersey.  Approximately 90% of this material was primary sludge (not sub-
jected to biological treatment).  The remaining 10% consisted of "partially
digested" sludge derived from a separate area.

     Routine practice at the treatment plant is to add 1 kg of chloride
based polyelectrolyte polymer conditioning agent per metric ton of dry
solids followed by dewatering in a belt filter press.  The resultant sludge
cake has a moisture content at 103 °C of approximately 75% (wet weight basis
of expression) and the oven dry material has a volatile solids content of
approximately 75%.

     To provide porosity, sludge cake and virgin woodchips (nominally 2.5 x
2.5 x 0.6 cm) were combined (approx. 1:1.8, w/v) and mixed in an industrial
pug mill.

     Composting pile.  A pile consisted of a mixture of sludge and woodchips,
with a base and cover of woodchips only.  The pile contained approximately 6
metric tons (Figure 1).

                                    633

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     Ventilation system.  Corrugated plastic hose (10 cm internal diameter)
 served as ventilation duct work.  Blowers capable of delivering up to  15 m^
 of air per minute were operated in the force pressure mode.

     Temperature control system.  A temperature controller with an adjust-
 able temperature set point continuously received and interpreted a signal
 from a thermistor in the pile (Figure 2,3).  When the signal indicated a
 temperature less than the set point the controller actuated the blower on a
 periodic schedule preset with a timer.  When the signal indicated a tempera-
 ture greater than the set point the controller directly actuated the blower,
 which remained in operation continuously until the temperature was lowered
 to less than the set point.  Thus the control system was based on the  feed-
 back of temperature information from a selected position in the pile.

     Pile temperature.  Representative temperatures are shown in Figure 4.
 In all of the piles the thermistor and a thermocouple were both at position
 1.  The temperature data from the period of feedback control are summarized
 in Table 1.  During this period the median temperature in pile A exceeded
 the controller setting for this pile by 3 °C, while the excess values  for
 piles B and C were 7 °C and 2 °C, respectively.

     In pile A, the temperature at position 1 during the period at feedback
 control was essentially that of the assigned set point (45 °C).  The only
 appreciable departure from the set point occurred between hr 92 to 136.
 During this period the peak temperature was 53 °C, at hr 112.  The departure
 occurred while blower operation was continuous.

     Control was generally less precise at the lateral positions (e.g., A 3
 and A 12).  In this direction the least precise control was at the outer-
 most position.  Higher 'temperatures occurred in the uppermost areas of the
 pile (e.g.,  compare the temperatures at positions A 1, A 6 and A 13).

     Similarly, in piles B and C during the period of feedback control,
 there was a close correspondence between the set points (55 °C, and 65 °C
 respectively) and pile temperatures near the thermistors (positions B  1 and
 C 1).  Lateral to these positions, and in the upward direction, control was
 less precise.  In pile C the ventilation scheduled by timer generally induced
 early,  precipitous,  temperature declines.

     Performance at selected temperature set points.  Three piles, each con-
 sisting of 6 metric tons of sludge, were made on 10 May 1979, and the main
part of the experiment was terminated on 31 May.  The set points assigned to
 the temperature controllers were:  pile A, 45 °C; pile B, 55 °C; pile C,
65 °C.   During the experimental period, the ambient temperature varied
between 8.9  °C to 30.6 °C and total rainfall was 13 cm in 12 occurrences.

     Blower  operation.  In pile A blower operation first exceeded that
scheduled by timer at hr 12,  indicating that the controller had responded to
a thermistor temperature of > 45 °C (Figure 3).  This marks the start of
the period of temperature feedback control.  Blower operation was nearly
continuous from hr 80 to 150.   Feedback control terminated at hr 352, and
blower  operation reverted to  that  scheduled by timer (7% of the time).

                                    634

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                                                      1
                                                      c
                                                      o
                                                      V-*
                                                      s
                                                      o

                                                      Qu
Figure 1.  Six-metric-ton composting pile cross  section
                          635

-------
                          Table 1.  Temperature During the Periods of Blower Demand
    Controller set               Period of blower              Pile tempera-
      point (°C)                    demand (hr)                 ture (°C)                 Observations a

                                                             Range       Median          No.     % >  60°C
en
&     45 (pile A)                   12 to 352               25 to 63       48           1020        1.8

      55 (pile B)                   26 to 214               18 to 78       62            641       58

      65 (pile C)                   28 to 84                64 to 74       67            182      100
    3  60 °C is considered the threshold to significant self-limitation

-------
GJ
                                                           Blower
                                    Figure 2.  Schematic of the temperature
                                               feedback-blower control  system

-------
                                                              Blower duration (% of time on)
CO
oo
         OQ
          (0


          U)
3



p>
rr
p-
O
3
CD
                 O
                 c


-------
M
3

J2
03
O

(0
0)
03

O>
Q.
E
501    2    34

      Time (hours x 100)
                                                        5'cO    1
                  Figure 4.   Temperatures at  selected points
                                        639

-------
     The decrease in moisture content during composting indicates  organic
matter decomposition.  This is because drying and decomposition are linked
via heat output and vaporization.   The observation that pile A dried faster
than piles B and C therefore represents a field-scale demonstration of the
heat output-temperature interaction concept, which requires  the most extensive
microbial heat output to occur in the coolest pile.

     For pile B, the period of feedback control was  from hr  26 to  214, during
which blower operation peaked at 45% at hr 70.   For  pile C,  the period of
feedback control was at hrs 28 to 84, and the peak was 12% at hr 50.

     Carbon dioxide.  Where the record is complete (piles A  and C) the highest
C02 levels occurred prior to the initiation of temperature feedback control
(Figure 5).  During the period of feedback control the C02 values  averaged
approximately 2, 3, and 4% for piles A, B, and C, respectively.  During the
terminal period of timer-scheduled blower operation the C02  values were
lower.

     pH.  The starting pH was 6.3 and this increased, at a different rate  in
each pile, to approximately 8.2 (Figure 6).  This was followed by a slight
decline.  A secondary increase in pile A started after hr 380.

     Moisture content.  In pile A, the starting moisture content of 76%
decreased to 22% in 15 days (Figure 6).  In piles B and C, the decrease was
to 40% in 18 days.

Discussion

     A practical means of controlling temperature was devised in the form  of
the temperature-feedback control system in conjunction with  forced-pressure
ventilation.

     A definitive comparison of pile A (coolest), pile B (intermediate), and
pile C (hottest) based on C02 output and heat output is not  possible in this
open system, as these measurements of decomposition cannot be reliably
quantified from the data.  However, the results of the odor  test indicate
that the rate of decomposition was A > B >  C.  The moisture  content data
provide a similar indication as the decrease in moisture content during
composting indicates organic matter decomposition.  This is  because drying
and decomposition are linked via heat output and vaporization.  As indicated
previously, the observation that pile A dried faster than piles B and C
therefore represents a field-scale demonstration of the heat output-tempera-
ture interaction concept, which requires the most extensive  microbial heat
output to occur in the coolest pile.

OHIO AGRICULTURAL RESEARCH AND DEVELOPMENT CENTER AT SOUTH CHARLESTON, OHIO(5)

     One of the main purposes of this research was to demonstrate if the
temperature controlled composting developed at Rutgers and explained previous-
ly here can be implemented in a mechanized enclosed tank reactor.   For this
purpose an existing composting facility operated by Paygro,  Inc.,  has been
used with the permission of the owners.  Although Paygro, Inc., operates

                                      640

-------
Interior Carbon Dioxide


__*
     Q          W
                                        (percent volume)


                                        o         w    o
                                           C/5
                                           CD
                                           O1
                                           CJ1
                                            o
                                           O
                                                TJ

                                                <5"
                                                CD
                                                                                  CO
                                                                      o
                                                                      O
                                                                          3
                                                                          te
Figure  5.   Carbon dioxide content in  the three  piles

-------
ro
       13
       33

       H-
       3
       rt

       ^
       0)
       (D
       ro
       01
                        0
100
200             300

    Time (hour)
                                                                                       400
                                                                                                       500

-------
                                                        a)
                                                        E
                 ejrusjouu
Figure 6B.  Moisture content in the three piles
                        643

-------
mechanical equipment and provides other needed services, the experiments
were designed, operated and evaluatred by a research team from Ohio Agricul-
tural Center.

Description of Paygro Bioreactor

     The bioreactor was constructed in 1972 and has been in operation since
then.  Until recently the system has been used mainly for composting feed lot
manure and bark.  The composted materials have been bagged and sold to the
horticultural market.  During the last year portions of the facilities have
been used for research with municipal sludge.  A diagrammatic layout of the
facilities is shown in Figure 7.

     The composting operation for the manure consists of feeding a mixture
of wet manure and sawdust, used as bedding in the cattle pens, to the meter-
ing hopper via front end loader.

     The metering system consists of a flat bottom hopper and incline drag
conveyor, all hydraulic driven with variable speed controls.  An operator
controls the feed rate from the metering system to the center conveyor system.

     A center conveyor, tripper car and indexing conveyor transports the
material to the reactors.

     The reactors are two parallel 122 m long structures, each 6 m wide by
3 m deep.  The reactor walls support the tripper car, indexing conveyor and
the digging machine.

     Air is forced through the reactors by a series of fans located along
the reactor wall.  One 7-1/2 HP fan provides 1.4 to 2.4 m3/s of air for a
reactor contents of approximately 226 m3.  The fans are designed to blow
air up through or pull it down into the reactor contents.

     Air is equally distributed through a perforated plate and a gravel
support bed located in the bottom of the reactor structure.  The material is
aerated for 14 to 21 days.  While in the reactor the mix is removed and
remixed 1 to 2 times before leaving the reactor for storage and bagging.
There is no requirement for recovery of any bulking agent for reuse.  The
material enters the reactor at 40 to 50% dry solids and leaves at 60 to
70% dry solids.

     The material is removed by the use of the digging machine and trailing
conveyor (extractoveyor).  This equipment travels the entire length of the
reactors on rails and is hydraulically operated.  The extractoveyor dis-
charges the material to the center conveyor.  The center conveyor either
relocates the material by the use of the tripper car and indexing conveyor
or discharges the finished compost material to storage.

Experiments

     Raw municipal sludge was received from the Columbus Southerly Plant on
May 26 and 27, 1981.  It was mixed with recycled compost and hammer-milled

                                     644

-------

-------
bark (approximtely 80% red oak) at volume ratios of 1:2-8:1*6 (sludge:
recycled compost:bark).  The mixture (Table 2) was loaded into the reactor
on May 28, 1981.   The mean percent dry solids of the reactor feed was
40.8 and the mean percent volatile solids was 72.9.

     The reactor feed was placed in two adjacent 12 m sections (A and B)
of the reactor, which were separated by a plastic wall.  Each section was
aerated with a separate fan to be operated under different aeration schemes.
However, an air leak was discovered between the sections on the first day.
Aeration for each section therefore could not be controlled separately.
Fans were controlled by 30 min timers and were on 60% of the time (18/30
min) throughout the trial.

     Automatically collected C02 data are not yet available for this trial.
However, the percent C02 in exhaust air reached a high of 14% on the first
day and remained below 7% throughout the rest of the trial.  The sum of 02
and CO2 was constant throughout the trial.

     Free airspace (FAS) values for the reactor feed, the reactor product
and the compost after 10 weeks of curing were 49, 52, and 45%, respectively.

     Temperature was recorded at the fans and 40 locations in each of the
Sections A and B (Figure 8).

     The compost was turned twice.  It was removed on June 1 and re-entered
the reactor on June 2.  The second turn occurred on June 10 and 11.  It was
finally removed from the reactor on June 18.  The total composting period in
the reactor therefore was 326 hrs (18 days).  The actual time elapsed from
the start to the final removal was 23 days.

     Differences in the volatile solids and dry solids levels between
Sections A and B were not significant (Table 3).  Drying occurred at signi-
ficant levels (5%) throughout the 18 day period.

     The mass balance is presented in Table 4 (pooled data from Sections A
and B).  The percent loss in volume of the total mass in 18 days was 22.4%.
The percent loss in wet weight was 40.8.  The percent loss in dry weight was
15.1 and the percent loss in volatile solids (of original) was 21.1.

     The distribution of the moisture (percent dry solids) with depth in the
reactor at the time of the second turn (day 11) and at removal (day  18) is
presented in Tables 5 and 6.  The surface of the compost did not dry through-
out the trial.  Considerable drying occurred at the 15 cm depth (less condensa-
tion than at the surface).  There was little difference (5% level) in drying
at deeper levels in the reactor.  No significant wall effect was detected,
except for near the end of the trial, when samples from within 15 cm from the
wall of the reactor were significantly wetter than all others.

     Significant differences (5%) in levels of volatile solids destruction
were not observed among the various depths in the reactor at either  the 11
or the 18 day period (Tables 7 and 8).  Wall effects were either not
detectable or did not show a consistent pattern.

                                    646

-------
        Table 2.  Description of Components and Reactor Feed Mixture
Component
Raw sludge c
Recycled compost
Bark
Reactor feed d
Mixing ratio a
(volumes)
1
2.8
1.6
-
Bulk density
kg/m3
1063
605
414
679
Mean %
solids
14.5
58.0
57.2
40.8
Mean %
volatile
solids b
72.7
65.3
84.5
72.9
a  Determined by compacting (0.7 kg/cm^, 10 Ibs/sq in) samples into a 28.3
   liter (1 cu ft) square box.

k  Mean of 10 or more samples of approximately 100 gm wet weight each.

c  Raw municipal sludge (98.4 M tons net weight) was obtained (5/26/81)
   from the Southerly Treatment Plant, Columbus, Ohio.

d  Total volume = 439 m3.
                                     647

-------
                       Length of tank filled (80 feet)
CTl
-P»
00
"^
9)
£
a

-------
to
                   Table 3.   Changes  in Percentages Solids  and Volatile  Solids During  Composting
                                     in Two Sections  (A and B)  in the Reactor



Reactor feed
First turn
(day 4)
Second turn
(day 11)
Reactor product
(day 18)

Section
sampled
A B

A B
A
B
A
B
Percent
Number of Percent solids volatile solids
samples Mean 95% Conf. Int. Mean 95% Conf. Int.
18 40.8 + 1.3 72.9 + 1.6 a

10 43.3 + 0.4 73.3 + 1.3
10 52.0 + 0.4 69.9 + 1.1
10
10 58.4 + 1.4 64.2 + 0.7
10
       Means  followed by a common  line  are not  significantly  different  according  to  Duncan's  new multiple
       range  test  (P = 0.05)  (For  description of Duncan's  test,  see  reference  6).

-------
                           Table 4.   Materials  Balance for  Composting  Trial  3

Reactor feed
Reactor product
o, Loss during
o composting^
% loss
Volume3
(m3)
439.4
341.0
98.4
22.4
Bulkb
density
(kg/m3)
678.5
517.7


Wetc
weight
(M tons)
298.2
176.5
121.7
40.8
% Dryd
solids
40.8
58.5


% Volatile4
solids
72.9
64.2


Weight drye
solids
(M tons)
121.7
103.3
18.4
15.1
Weight6
water
(M tons)
176.5
73.2
103.3
58.5
PH
5.5
6.5


a  Measurements were made in the reactor (error < 4%).




"  See Table 1 for explanation.




c  Calculated from bulk density and volume.




"  Means of a minimum of 10 samples of approximately 100 g wet weight each.




e  Calculated from wet weight and percent solids or volatile solids.




f  After 18 days in the reactor.

-------
          Table 5.  Mean Percent Solids Distribution in th Reactor
                       at  Time of  Second  Turn  (Day  11)
Depth
(inches from
surface)
2
6
31
52
73
94
Means for
distance
from wallc
Distance from wall
(inches from east wall)
6
38. Ob
50.9
52.4
51.9
49.9
50.3

48.8

24
39.3
53.1
52.9
50.0
49.7
54.0

49.8

80
36.9
47.4
50.6
51.1
52.1
53.0

48.5

107
40.5
47.0
51.7
51.7
54.6
52.2

49.6

133
40.4
46.4
50.0
52.2
52.3
52.0

48.9

160
37.6
45.3
49.6
51.4
51.8
55.0

48.5

Means
for
depth a
38.8
48.3
51.2
51.4
51.6
52.7


a  Means (of 24 samples each) joined by a common line are not significantly
   different according to Duncan's new multiple range test  LSD.Q5 = 1-5.

°  Means of four values.

c  No significant difference among means (P = 0.05).
   1 inch = 2.54 cm
                                    651

-------
         Table 6.  Mean Percent Solids Distribution in the Reactor
                        at Time of Removal (Day 18)
Depth
(inches from
surface)
2
6
31
52
73
94
Mean for
distance
from wall0
Distance from wall
(inches from east wall)
6
41. 2b
59.6
60.5
62.7
58.6
57.2

56.6

24
40.8
54.3
58.1
60.2
60.1
55.1

54 . 8

80
41.9
50.6
56.7
57.6
60.1
60.0

54.6

107
41.3
50.0
56.0
56.3
57.7
62.6

54.0

133
41.0
54.9
56.6
57.6
56.7
61.2

54.7

160
40.6
54.9
57.5
55.9
58.3
60.3

54.6

Means
for
depth a
41.1
54.0
57.6
58.4
58.6
59.4


a  Means (of 24 samples each) joined by a common line are not significantly
   different according to Duncan's new multiple range test  LSD_o5 = 1-6.

b  Mean of four values.

c  No significant difference among means (P = 0.05).
   1 inch = 2.54 cm
                                     652

-------
     Table 7.  Mean Percent Volatile Solids Distribution in the Reactor
                       at  Time of  Second  Turn  (Day  11)
Depth
(inches from
surface)
2
6
31
52
73
94
Means for
distance
from wallc
6
69.7
69.6
72.9
67.9
70.4
75.1
70.9

24
70.1
69.5
71.5
72.1
70.1
69.6
70.6

Distance from wall
(inches from east wall)
80 107 133
69.9
67.6
67.1
70.6
70.5
68.3
68.5

69.8
68.7
71.9
69.8
67.6
67.4
69.2

69.8
70.1
67.7
70.2
69.9
69.6
69.6

160
67.9
70.6
71.6
72.3
72.8
68.7
70.7

Means
for
depth a
69.2
69.3
70.5
70.5
70.2
69.8

a  Means (of 24 samples each) joined by a common line are not significantly
   different according to Duncan's new multiple range test (P = 0.05).

b  Mean of four values.

c  No significant difference among means (P = 0.05).
   1 inch » 2.54 cm
                                     653

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         Table 8.   Mean Percent  Volatile Solids  Distribution  in  the
                Reactor at Time of Compost Removal (Day 18)
Depth
(inches from
surface)
2
6
31
52
73
94
Means for
distance
from wallc
6
62. 9b
64.6
64.1
65.3
63.7
64.6

63.8

24
66.9
65.2
61.8
65.3
65.0
63.1

64.5

Distance from wall
(inches from east wall)
80 107 133
65.0
63.6
62.6
65.3
65.2
66.8

64.7

68.3
63.4
64.0
65.2
63.1
63.7

64.6

66.2
63.7
61.8
63.8
63.7
63.1

63.7

160
66.0
62.4
64.3
63.7
62.5
64.9

64.0

Means
for
depth a
65.9
64.4
64.4
63.9
63.9
63.1


a  Means joined by a common line are not significantly different according
   to Duncan's new multiple range test  LSD_05 = 1-4.

b  Mean of four values.

c  No significant difference among means (P = 0.05).
   1 inch = 2.54 cm
                                     654

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       Table 9.   Mean Temperatures  of  Compost  in Various  Thermocouple
                    Positions for Selected Time Periods
Total hours
elapsed


88

First Turn


184

Second Turn


160

Removal


432 (total)

Depth
(inches)
6
31
52
94

6
31
52
94

6
31
52
94

6
31
52
94

Wall
_ b
-
31.4
20.3

34.3
-
32.9
22.4

45.7
-
39.4
25.3

39.1
-
34.4
22.7
Distance
6
_
-
33.5
22.2

47.8
-
36.0
18.4

53.0
-
41.5
26.4

49.7
-
36.9
21.5
from wall
12
_
-
41.7
24.6

49.9
-
34.7
24.6

53.6
-
41.8
24.0

51.2
-
38.3
25.7
(inches)
24
tl_
-
44.0
35.2

51.1
-
49.4
30.9

54.6
-
40.3
29.3

52.4
-
45.7
31.5
a
80
	
73.1
71.4
59.3

58.9
59.0
54.5
34.9

59.2
59.5
56.5
37.0

59.0
62.5
59.0
41.3
a  Means of readings taken every 4 hr in four locations for the wall, 6",
   12" and 24" positions.  Means of eight locations for the 80" position.

b  Missing data.
                                    655

-------
                   _  60
CTv
Ul
                   O
                   o
                   c
                   4-*
                   (D

                   0>
                   Q.


                   (1)
60-
50-
                       40-
                                                          Days
                                   Figure 9.   Mean temperatures and  fan  operation time
                                              for  the pile with set temperature of 65  °C

-------
JC
\
c

E

_c

01

E
o
o
     70
     60'
 CO

 I
 i    so
     40
                                      4

                                       Days
              Figure  10.  Mean temperatures and fan operation time

                         for  the  pile with set temperature of 45 °C

-------
     Mean temperature readings for the various thermocouple positions in
the reactor (combined means of Sections A and B) are shown in Table 9.
The temperature of the compost in the bottom foot of the reactor was near
that of the air temperature at the fan.  At a depth of 127 cm the tempera-
ture was similar to that of the rest of the compost at higher locations.
Wall effects were obvious up to 30 cm into the reactor.

     A comparison of the Paygro bioreactor performance published accounts
of the aerated static pile shows the following:
Method
Paygro
Beltsville
Washington
Composting
days
18
42
42
% loss in
wet weight
40.8
31
29
     A comparison of the data presented here with data from Rutgers experi-
ments shows that drying was similar to that of Rutgers results obtained at
55 and 65 °C in 18 days, but less than that obtained at 45 °C.

Test of Automated Equipment

     In a second set of experiments, two 12 m reactor sections were
separately aerated.  The feedback temperatures were set at 45 and 65 °C.
The main purpose of the experiments was to evaluate the performance of re-
actors at two different temperatures and to test the operation of feed-
back mechanism and the computerized data collecting system.  The experi-
ments have just been completed in September 1981 and most of the data
analyses have not been completed.  However, the mean temperatures and fre-
quency of air blowing operation over a period of 9 days (Figures 9 and
10) indicate that, the control mechanism operates successfully, expected
temperatures are maintained, and blower capacities are adequate.

CONCLUSIONS

     The research at Rutgers and Ohio Agricultural Research Center has not
yet been completed.  However, from the results obtained thus far and pre-
sented here, the following conclusions can be reached:

     1.  Two independent sets of experiments confirmed that temperature
controlled aeration in the forced pressure mode can maintain the tempera-
ture of a composting pile at a desired level.
                                     658

-------
     2.  By maintaining the temperature at 45 to 65 °C range, weight losses
obtained were higher than the weight losses obtained in uncontrolled compost-
ing operations.

     3.  In an enclosed mechanized system, the temperature was maintained
more uniformly throughout the experimental period and throughout the compost-
ing pile cross section.

     4.  In an enclosed mechanized system, temperature controlled forced
aeration system appears to provide larger weight losses and drying than the
open systems.
                                      659

-------
REFERENCES

1.  United States Department of Agriculture and United States Environmental
    Protection Agency,  "Manual for Composting Sewage Sludge by the Beltsville
    Aerated-Pile Method," EPA-600/8-80-022, May 1980.

2.  United States Environmental Protection Agency,  "Composting Processes to
    Stabilize and Disinfect Municipal Sewage Sludge," EPA 430/9-81-011, July
    1981.

3.  Finstein, Melvin S.,  et al., "Sludge Composting and Utilization: Rational
    Approach to Process  Control," Cook College, Rutgers University, September
    1980.

4.  Finstein, Melvin S.,  Rutgers University, Monthly Reports submitted to
    Wastewater Research  Division, U.  S. Environmental Protection Agency,
    Cincinnati, Ohio, 1978-1981.

5.  Hoitink, Harry A. J., Ohio Agricultural Research and Development Center,
    Monthly Reports submitted to Wastewater Research Division, U. S. Environ-
    mental Protection Agency, Cincinnati, Ohio, 1981.

6.  Steel, Robert G. D.,  and Torrie,  James H.,  "Principles and Procedures
    of Statistics," McGraw-Hill Book Company, Inc., New York, 1960.
                                     660

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  THERMAL PROCESSES FOR CONVERSION OF SLUDGE:
    STATUS, EPA RESEARCH, FUTURE DIRECTIONS
             J. B. Farrell, Ph.D.
         Wastewater Research Division
 Municipal Environmental Research Laboratory
    U.S. Environmental Protection Agency
               Cincinnati, Ohio
This paper has been reviewed In accordance with
the U.S. Environmental Protection Agency's peer
and administrative review policies and approved
for presentation and publication.
         Prepared for Presentation at:
      8th United States/Japan Conference
                       on
         Sewage Treatment Technology

                  October 1981
                Cincinnati, Ohio
                      661

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THERMAL PROCESSES FOR CONVERSION OF SLUDGE:
STATUS, EPA RESEARCH, FUTURE DIRECTIONS

J. B. Farrell, Ph.D.
Wastewater Research Division
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio

INTRODUCTION

     "To live is to change, To be perfect is to have changed often" (John
Cardinal Newman).  Cardinal Newman's sage observation referred to growth of
the human spirit, but his words are equally appropriate to technology.   What
appears appropriate in one decade may in the next decade be thoroughly out-
moded by advances in technology, by new knowledge, or by a change in economic
conditions or incentives.

     Thermal processing of sludge, which has meant incineration of sludge in
years past, has been adversely affected by new knowledge and concern about air
pollution, and by the increase in cost of fuel relative to other costs.   Inter-
est in it has declined and other methods, particularly land application and
landfill have been advocated.  These alternatives, however, have not proved to
be panaceas.  Other concerns, among them protection of the land from contami-
nation, have arisen, that have made these latter methods seem inappropriate
for certain contaminated sludges.  It is evident that despite some problems,
there are many situations where properly conducted thermal methods are the
best solutions to the sludge disposal problem.

     The U.S. Environmental Protection Agency (EPA) has continued a modest
thermal conversion program over the years, aimed at reduction of pollution
from conventional incineration and development of new approaches to thermal
conversion.  The following presentation reviews the status of thermal conver-
sion processes, and outlines current EPA research and development efforts and
directions.

     In order to conduct a discussion of thermal conversion, it is desirable
to classify the subject matter in an orderly fashion.  The usual approach,
organization by the processing procedure (e.g., incineration, starved-air
combustion, pyrolysis, etc.) is unwieldy, so a different approach is used
herein.  The subject matter is organized by the nature of the desired product
of the thermal conversion process.  Most processes have two or more streams
leaving the process, so a choice of the desired stream, usually not a difficult
one, must be made.   The scheme proposed is the following:

              Nature of Desired Product

         (a)  Thoroughly combusted gases
         (b)  Combustible gases
         (c)  Combustible liquids
         (d)  Decontaminated water
         (e)  Solid products

                                     662

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 The classification of processes under these major headings is shown in Table
 1.  There are many more potential processing routes to the desired product
 than are indicated.  Only those which have been seriously proposed are pre-
 sented  in the table.  The discussion that follows expands on each topic out-
 lined in Table 1.

Table 1.  Classification of Thermal  Conversion  Processes  by  the  Desired  Product

          I Thoroughly Oxidized Gases

                  (a)  Incineration of sludge
                  (b)  Addition of low-grade fuel to sludge incinerator
                  (c)  Addition of sludges to other combustion processes
                      (solid waste incinerator, cement manufacture, power
                       plants)
                  (d)  Symbiotic processing

         II Combustible Gases

                  (a)  Partial combustion of sludge
                  (b)  Partial combustion of sludge with another waste or
                      low-grade fuel
                  (c)  Symbiotic processing

        III Liquefied Products

                  (a)  Pyrolysis of sludge
                  (b)  Pyrolysis of sludge with gaseous reactants (H2, CO)

         IV Decontaminated Water

                  (a)  Wet oxidation in a deep well

          V Solid Products

                  (a)  Sludge drying by Carver-Greenfield process
                  (b)  Add sludge to mix and make bricks
                  (c)  Coincineration of sludge and solid waste ash followed
                      by fusion, to make aggregate

 OXIDIZED GASES

     The conversion of sludge solids to oxidized gases and an inert residue is
 merely  the time-honored process of incineration.  A variety of options are
 available and are discussed below.

 Incineration of sludge

     Estimates have been made that 25 percent of the sludge in the United
 States  is incinerated.  Generally, undigested sludge is dewatered to about 20-
 25 percent solids and is incinerated in multiple hearth furnaces.  Usually,
 addition of high grade supplemental fuel, such as natural gas or No. 2 fuel

                                   .  663

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oil is required to reach combustion temperatures;  if afterburning is required,
more supplemental fuel is needed.  Fuel requirements are substantial, particu-
larly if the sludge cake solids are near or below 20 percent;  excessive fuel
requirements have caused many communities to shut down their incinerators and
use alternative sludge disposal methods, such as lime treatment followed by
landfilling.  Besides the disadvantages of the high cost of fuel, incineration
has a bad public reception because of the conviction of the public that incin-
eration, particularly the stack discharges, pollute the environment.

     EPA research on conventional incineration has shown that  incineration
stack discharges create some pollution but that particulate discharges are
small and the established standards (0.65 g/kg dry feed) are easily met.  Cer-
tain metals, particularly lead and cadmium, are poorly retained; as much as 10
percent escape collection, whereas bulk particulate losses (volatiles-free
basis) are about 0.2 percent.  Cadmium and lead escape because:  (1) the pro-
cess of combustion converts much of them into a form, gaseous  or particulate,
in which they are swept out of the furnace, and (2) in the cooled gases that
approach the wet scrubbers, they are present as exceptionally  fine particles.
Both of these effects contribute to large percentage losses.

     Despite the unfavorable results with lead and cadmium, environmental
hazard is slight, primarily because quantities of these substances are low in
sludge.  Nevertheless, to overcome public uneasiness and to permit inciner-
ation to be used when cadmium and lead concentrations are high, a demonstra-
tion is appropriate in which particle collectors that are efficient in the
fine particle range are used, and good removal of lead and cadmium is demon-
strated.  Additionally, basic studies are needed to investigate whether tem-
perature level, oxygen concentration, and equipment design can be manipulated
to lessen the initial transport of cadmium and lead into the gas phase that
leaves the furnace.

Addition of low-grade fuel to sludge incinerator

     The need to add supplemental fuel to a sludge incinerator is a serious
economic obstacle.  One alternative is to dewater sludge with more costly
dewatering devices, such as diaphragm filter presses, which produce a much
drier cake.  Another alternative is to add a cheap low-grade fuel, such as
refuse-derived fuel (RDF), woodchips, or even coal to the incinerator to
supply the necessary heat.

     Experiments in which coal or woodchips were added to a multiple hearth
sludge incinerator were conducted at Minneapolis, St. Paul  (1).  The investi-
gators found that fuels savings were considerable.  When ground bituminous
coal (100$ through 8 mesh) was added to the sludge cake, it could be used to
replace from 50 to 80 percent of the natural gas normally required.  The coal
could be used to replace nearly all of the natural gas, but this increased the
possibility of thermal excursions with subsequent damage to the incinerator
from overheating.  The authors found that use of coal unduly complicated the
plant required for sludge combustion, since equipment had to be explosion-
proof, storage was needed, and operating labor requirements increased.  Their
experiments with woodchips were successful, and handling problems were fewer
than with coal.  Use of anthracite coal was unsuccessful; much of it passed

                                   .  664

-------
 through  the  furnace unburned  (volatile  solids  in ash  increased  from 0-U$  to
 20-30%)•

      The use of  RDF in  the  form of  fluff was demonstrated at Contra Costa (2)
 in  the  incineration mode  and  in the  starved-air combustion mode  (see a  follow-
 ing section).  Best throughput rates were achieved when the fluff was inserted
 on  the  third hearth and sludge cake  introduced on the top hearth.  Emissions
 were lower when  sludge  and  RDF fluff were premixed and introduced on the  first
 hearth  but throughput rates were  lower.

      A  facility  has been  designed and installed at Duluth, Minnesota, in  which
 sludge  is to be  burned  in fluidized  bed incinerators, with RDF,  probably  as
 fluff,  to be added as supplemental  fuel.  This startup has been  delayed by
 several  years, but startup  is now imminent.

      The technology in  which a low-grade supplemental burnable material,  such
 as  coal,  RDF, or woodchips, is introduced into a sludge incinerator appears
 sufficiently well established to  permit design of an  operating  facility with
 an  excellent likelihood of  success.  Despite the adequate state  of knowledge,
 there are very few planned  or operating installations  (other than Duluth  - see
 above).   Either  potential users are  not aware of the  state-of-the-art or  have
 made the  decision that  other approaches are more promising.

 Addition  of  sludge to other combustion processes

      Sludge  cake could  be destroyed  by addition to any combustion process,
 provided  it  does not degrade the  discharged gases, the product,  or the process
 equipment.   Power plants  using coal  or oil could also burn sludge; however,
 there has been no interest  from this quarter even though there is no "product"
 that might be degraded.   Concern  about pollution in the discharged gases  and
 about possible harm to  equipment  may be the reason for lack of interest.  The
 fact that power  plants  are utilities which can "pass  through" fuel costs  to
 customers may be a factor.  Cement manufacturers have shown interest in
 destroying organic pollutants but have shown no interest in sludge, possibly
 because they  fear contamination of the product by the sludge ash.

      The  only combustion process  that has been applied in a significant way to
 sludge combustion is solid waste  incineration (3).  The disadvantage of high
 cost  of fuel  is eliminated but other disadvantages are introduced.  Sludge and
 solid waste must be mixed properly.  A recent concern has been air pollution,
 in particular, the fear that dioxin is formed in solid waste incineration.  In
 at least  one case (Hempstead,  N.Y.), startup of an incinerator is being held
 up because of concerns  about formation of this chemical (U).

     Another reason for slow activity in this potentially attractive route for
 sludge disposal has been the method of financing sludge disposal facilities.
 A solid waste-sludge incinerator  is federally supported by EPA's Construction
 Grants Program only to 75 percent  of the cost of a facility for destroying
 sludge alone.  Because a facility for destroying a municipality's solid waste
 and sludge will be much more costly than a facility to destroy sludge alone,
municipalities are inclined to search for a sludge only disposal method rather
 than provide capital funds from their own resources for the extra increment of

                                     665

-------
cost needed for the codisposal facility.

Symbiotic processing

     Symbiosis is defined as the living together of two dissimilar organisms
in close association.   Symbiotic processes can be defined as two separate but
intimately related processes,  related for example by use of the product of one
(or both) in the other process.  The coincineration facility at Ansonia,
Connecticut, is an excellent example of a symbiotic process.  The plant in
Krefeld, Germany, uses similar technology.  Here, flue gases from a solid
waste incinerator are used to dry sludge, after which the dried sludge is
disposed of by combustion in the incinerator.

     The tying together of two processes in a symbiotic relationship generally
involves little development work because the processes are not substantially
changed.  However, process rates and material flows have to be coordinated for
a successful symbiosis.  Other than the Ansonia plant and a plant at Harrisburg,
Pennsylvania (steam generated by solid waste burning dries the sludge), there
are no known plants in the United States of this type.  However, opportunities
appear to abound, and more applications may be expected in the future.

COMBUSTIBLE GASES

     Sludge can be converted to combustible gases in a process that involves
sludge either alone or supplemented by other combustibles such as solid waste.

Process for sludge alone

     Sludge can be converted to combustible gases by pyrolysis, where heat is
transmitted indirectly to the sludge, by contact with reactive hot gases (e.g.,
steam reforming), or by partial combustion.  Partial combustion, also called
starved-air combustion, has been the route that appears the most practical and
has received the most attention.

     In the United States, an incinerator, designed for either incineration or
starved-air mode, has been built at Arlington, Virginia, using sludge cake
produced by a filter press as feed.  This unit is not yet in use.  It is planned
to use starved-air combustion both at the City and County of Los Angeles plants
on completely dried sludge.  EPA plans to evaluate performance when these
facilities come on stream.

Processes which include non-conventional feed supplements

     Because the sludge and its decomposition products are not thoroughly
combusted, heat release in the primary reactor per unit mass of feed  is less
for starved-air combustion than for incineration.  Consequently, there  is a
need either to lessen the heat requirement in the primary reactor by  using a
very dry sludge cake, or alternatively to increase the heat release by  adding
a dry product that adds to the heat of combustion.  One process (2) uses RDF
as a supplemental fuel added to a conventional multiple hearth furnace.  This
process has been proposed for Memphis, Tennessee, although a final decision
has not yet been made.  Rochester, New York (5) appears to be going ahead with

                                     666

-------
 its  plans  to  utilize  this  process,  using  RDF  as  supplemental  fuel.  No  addi-
 tional  development  work  on this  processing  approach  appears to  be needed  at
 this time.  EPA will  attempt  to  evaluate  process performance  and report on
 results when  the  Rochester plant goes  on  stream.

      Three processes  that  produce combustible gases  by  adding another fuel to
 sludge  are outlined in summary form in Table  2.   Two processes, the Purox pro-
 cess and the  Sanoplex have many  similarities.  In the Purox process, compressed
 slugs of pre-ground solid  waste  (with  added sludge cake) are  charged to the
 vertical shaft kiln.  The  mass is partially combusted using oxygen.  The
 resulting  fuel gas  is cleaned and used in the vicinity  for power generation
 and/or  steam  production.   Experiments  with  sludge have  proven successful, but
 no installations  have been made.  Evidently,  economic considerations are  not
 sufficiently  attractive.

      The Simplex  process (6)  uses premanufactured fuel  briquettes charged to a
 vertical shaft kiln,  and carries out partial  combustion using oxygen.   The
 briquettes  are a  mixture of a caking coal and RDF.   A fuel gas  very similar to
 the  Purox  gas is  thus produced.   The process  appears very similar to the  Purox
 process.   However,  its inventors claim that gas  production rates per unit
 reactor volume are  much greater  because the briquettes  allow  much greater gas
 velocities  in the fuel bed.   In  the Sanoplex  version of the Simplex process,
 the  briquettes include sludge.   EPA-sponsored research  has shown that accept-
 able briquettes can be made in the  following  formulations:

      Ratio  of Coal/Waste                   1:1                2:1
     Sludge percent solids             20     HO         20     40
     Ratio of RDF to DSS               10:1   5:1        7:1    3:1
     Percent DSS in briquettes          3.5   6.3        3.4    8.8

          DSS = dry sludge solids
          RDF = refuse derived fuel

Note in the above table that acceptable briquettes can be made for RDF to DSS
ratios ranging from 10:1 to 3:1.  For typical communities in the United
States, the potential RDF to DSS ratio is about 10:1. Consequently, there is
ample RDF to dispose of all a community's sludge.

     Before further development work on this process is undertaken, economic
assessments of the process are needed along with expressions of interest from
potential users.  The process requires the interest and support of power pro-
ducers, groups concerned with solid waste disposal, and groups concerned with
sludge disposal.  Unless all three groups actively support the process and see
economic justification for it, successful completion of the development and
ultimate use are unlikely.

     The Vigil-UCD sludge gasifier resembles gas producers used before 1945 in
many parts of the world to convert low grade fuels into burnable gases.  Many
of these units were portable and provided fuel for internal combustion engines
that powered trucks and buses.  This technology disappeared from the scene
when cheap natural gas and gasoline became available.  The Vigil-UCD process

                                     667

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        Table 2.  Processes That Produce Combustible Gases By Partial
                  Combustion of Sludge Mixed with a Combustible  Additive
     Name
     Description
    Products
     Purox
     Sanoplex
     (a version of
      Simplex Process)
     Vigil-UCD
     Sludge Gasification
     System
Slugs of ground solid
waste and sludge cake
are charged to a
vertical shaft kiln,
and partially combusted
with oxygen

Briquettes of a caking
coal, RDF and sludge
cake are charged to a
vertical shaft kiln,
and partially combusted
with oxygen

Briquettes of source-
separated paper and
sludge cake are charged
to a down-draft gasifier,
and partially combusted
with air
350 BTU/ft3* clean
fuel gas and a
fused residue
350 BTU/ft3* clean
fuel gas and a
fused residue
140 BTU/ft3* fuel
gas and a char
residue

*BTU/ft3 x 0.0372
   = MJ/m3
(Vigil is the inventor,  rights tentatively assigned to University of California,
Davis) combines source-separated paper and sludge cake into pellets and gasifies
them in a conventional downdraft gasifier.  The gas can be used locally to
produce steam or can supply a gas turbine or a gas engine for electric power
generation.   Electric power generation is attractive in some states (e.g.,
California)  where laws require utilities to purchase power generated by such
processes.

     Pellets containing up to 15 percent dry weight of sludge were tested in a
pilot-scale  gasifier (6a).  A schematic drawing of the unit is shown in Figure
1.  Such gasifiers are much less expensive than incinerators because cot3truc-
tion is cheaper (firebrick is not needed) and capacity per unit volume is
higher.  Gas with a low heating value (dry basis, 0 °C, 1 atm)  of 5.2 MJ/m3
(140 BTU/ft3) was produced in the experimental runs.  An economic comparison
was made among the four alternative sludge disposal routes shown in Figure 2
(6b).  For communities below 10,000 persons, land application and landfill
showed marked advantages.  As community size increased, the relative economics
of the thermal processes improved.  For a population of 50,000 (see Figure 3),
co-gasification was more economical than the land based options unless the
land application sites were nearby, and much more economical than incineration.

     A small-scale demonstration of the Vigil-UCD gasification system is
planned in FY 1982.  A run of long duration is planned in which the gasifier
system will  be used to drive a gas engine.  Performance, maintenance, and
overall economic data will be obtained.
                                     668

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 AIR INLET
   PIPE

GAS DISPERSION
     ZONE
                         DISTILLATION ZONE &
                         ST***~.fS^**1*-* ilfl Ar*_y .hLtS'a*^*''*.'*- •-£*- •t*Tm^f'*i-*
 AIR INLET
   PIPE
GAS OUTLET
    PIPE
           FIGURE I.   SCHEMATIC OF  A DOWNDRAFT  GASIFIER,
                                 669

-------
             CHEM.
            .

            \
 SLUDGE
  (4%)
S: FILTER
::PRESS;
m-
                       d-ROF
                     PROCESSING
SLUDGE (40%)



         d-ROF
GASIFICATION
  SYSTEM
                                 I
   SOURCE SEPARATED WASTE PAPER  |
                           ASH-1 CHAR
                                                         ELECTRICITY
                                                        TO SANITARY
                                                          LANDFILL
                               Option 1
            ANAEROBIC
            DIGESTION
SLUDGE
 (4%)
                                      SLUDGE TRANSPORT
                           SLUDGE
                (4%)
                                       TO LAND
                                     APPLICATION
                               Option 2
             ANAEROBIC
              DIGESTION
 SLUDGE
  (4%)
                                             TO SLUDGE
                                              LANDFILL
                                         SLUDGE TRANSPORT
                               Option 3
SLUDGE
 (4%)
                          MHF INCINERATOR
                                                        TO SANITARY
                                                        ** LANDFILL
                                        ASH TRANSPORT
                               Option *
 FIGURE 2.    SLUDGE  PROCESSING AND DISPOSAL OPTIONS,
                                670

-------
              550
              500
              450
          Q   400
              350
          8
          o
             300
             250
             200
                                          OPTION 4
                                          INCINERATION
                                         OPTION I
                                         CO-GASIFICATION
OPTION 2
LAND  APPLICATION
                          20        4O       60        80
                   ONE  WAY DISTANCE  TO  DISPOSAL  SITE
                                  MILES
FIGURE 3.   ANNUAL COSTS  OF PROCESSING  AND DISPOSAL  OF SEWAGE  SLUDGE
            BY VARIOUS METHODS  FOR A COMMUNITY OF 50/000  PERSONS.
                                  671

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Symbiotic processing

     Symbiotic processing (see earlier discussion) is possible for processes
that produce combustible gases.  Staff of Wegman Engineers (7) are reportedly
working with wastewater authorities of Central Contra Costa,  California,  on a
starved-air combustion process in which sewage sludge cake is processed at
about 20 percent solids under starved air conditions in a multiple hearth
furnace.  The deficiency in energy needed for drying and decomposition of the
sludge is provided in part by combustible gas produced in an adjacent modular
solid waste incinerator, also operated under starved-air conditions.   Using
this combination of processes, it is not necessary to set up a refuse separa-
tion facility in order to produce RDF.  This concept is still in the  planning
stage.  Our laboratory will be following progress with great interest.

LIQUEFIED PRODUCTS

     When sludge or sludge-solids waste mixtures are subjected to high tempera-
tures and high pressure, sludge is converted to gaseous, liquid, and  solid
products.  By appropriate selection of catalysts, reactants such as CO and H£,
temperature, and pressure, product mix can be varied to emphasize liquid or
gaseous products.  Liquid product processes, discussed below, are favored by
high pressures.

     Work on such processes is at an early stage and no processes are near to
commercialization.  EPA has invested a small amount of funds into two processes,
one that produces a heavy oil with a large asphalt-like fraction and  another
that produces a fraction in the motor fuel boiling range.

Pyrolysis at high pressure

     A high pressure pyrolysis process for sludge liquefaction has been devel-
oped by Battelle Northwest Laboratory (BNW).  Experiments were carried out on
a batch basis in a stirred autoclave held at reaction temperature for one
hour.  During this period, gaseous products more volatile than water evolved
and were condensed outside of the autoclave, along with some water vapor.
After the reaction period, the residue was separated by centrifugation into ^r
aqueous supernatant and a char cake.  The char cake was extracted with solvent
to produce a heavy oil and a char or ash.  The heavy oil was vacuum distilled
to remove more volatile materials.  This step greatly increased the viscosity
and asphalt-like character of the heavy oil.

     Reaction conditions and yields are shown in Table 3-  Results indicate an
oil and asphalt yield of as much as 3f weight percent (ash-free basis).  Stand-
ardized tests for asphalt showed that the product had good potential  for use
as asphalt.

     All three product fractions have potential for fuel use.  Empirical chemi-
cal formulas and heating values are given below:
                                     672

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              Table 3«   Reaction  Conditions  and Yields  in Sludge Liquefaction Experiments

       Sludge^   Reaction    Pressure^         Reaction             Steam          Synthetic   Total
Run  Charged (kg) Temp (°C)     (atm)	Adjunct (5% by wt)    Volatile Oil  (g)  Asphalt (g)   Yield
HS-3
HS-4
HS-5
HS-6
^j
co
HS-7
HS-8
HS-9
HS-10
2.61
2.52
2.41
3-99
2.01
2.28
2.49
1.33
320
345
295
320
320
320
320
320
112
153
79
112
112
112
112
112
Na2C03
Na2C03
Na2C03
Na2C03
Na2C03
Na2C03
CaO
Na2C03
330
480
0
450
0
250
450
250
268
440
250
330
310
50
430
164
23
37
10
20
15
13
35
31
1.  Autoclave was 1 hour at reaction temperature
2.  Dry ash-free basis
3.  Estimated as saturated steam pressure at reaction temperature
4.  Weight of light oil and synthetic asphalt as percent of dry,  ash-free sludge

-------
     Product                Empirical  Formula        Heating Value
                                                  MJ/kc        BTU/lb
     Volatile oil           C1H1.9N0.3°0.9S0.04    39-2        16,900

     Asphalt fraction       C1H1.6N0.5°0.9S0.04    34.8        15,000

     Char (includes ash)            —             12.5         5,400

If the asphalt fraction can be used as a fuel extender, which appears likely,
economics could be improved because the process could be simplified (for
example, by eliminating the vacuum distillation step).   Preliminary economic
analysis for a plant to produce a light oil and asphalt shows a payout of the
initial capital investment in 10 years.  If both the light oil and the asphalt
fraction were used as a fuel oil, the payout time is estimated to be half as
long (5 years).

     The work carried out so far indicates feasibility of the process but
economics are uncertain.  More batch experiments followed by operation of a
continuous pilot plant will be needed to firm up data on yields, process con-
ditions, and product qualities.  The fuel production option looks more attrac-
tive than the asphalt option.  Decisions on further work efforts are awaiting
recommendations of a critical review of thermal conversion approaches but this
approach seems more promising than some others.

Pyrolysis at high pressure with gaseous reactants

     Worchester Polytechnic Institute (WPI) has proposed a high pressure lique-
faction process which uses thermal conditions similar to the BNW process.
However, in the the WPI process, a solid catalyst is used in the presence of
hydrogen.  In preliminary experiments, the sludge was suspended in a liquid
carrier (a paraffin oil).  All of the organic substances were converted to
liquid and gaseous products.  The need to supply hydrogen increases the cost
of the process substantially.  WPI has proposed to supply the hydrogen by
steam reforming part of the sludge to form hydrogen.

     Considerable experience has been obtained on performance of the WPI pro-
cess using solid waste as feed, but information on sludge is very limited.  A
short experimental program will be carried out using sludge as the feed.  A
decision on whether to go further than this with the process awaits the afore-
mentioned review of thermal conversion processes.

DECONTAMINATED AQUEOUS STREAM

     A sludge stream can be treated directly by strong oxidizing chemicals to
decontaminate it and oxidize its organic content.  By elevating the tempera-
ture, oxygen from the air can also be used for this purpose.  This latter
process is called "wet oxidation" and has been available for many years.  The
Zimpro "high oxidation" process is commercially available, and its effects are
well documented in the literature.  Only rarely does this method appear to be
cost effective.  Studies for Boston and New York showed that other thermal
destruction methods are less costly.  Important disadvantages are:  (a) the

                                      674

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high pressures needed (1500 psi),  (b)  need for expensive metals  or alloys  to
limit corrosion, and (c) high requirement for electrical power.

     A modification of this process,  the Wet-Ox process uses a different
reactor design but does not differ in any substantial way from the Zimpro  High
Oxidation process.  The claim is made that more efficient contact in the stirred
reactor allows use of lower temperatures and pressures to achieve the same
result as the Zimpro high oxidation process.  Recent work with the Wet-Ox
process for destroying industrial  waste has been published (8).

     A novel approach to wet oxidation has been proposed by the  Vertical Tube
Reactor Corporation.  In their process, a deep vertical concentric double  pipe
assembly (ca. 6000 ft deep) is used to produce the high pressures needed to
maintain water in the liquid state at the thermal conditions for wet oxidation.
No high pressure equipment is needed at the surface.  Heat exchange between
incoming and exiting liquid is efficiently accomplished by the pipe within a
pipe assembly, without the need for a cumbersome above ground double pipe  heat
exchanger.   Air under moderate pressure is pumped into the sludge as it is
pumped downward.  A third concentric pipe near the bottom of the pipe assembly
provides a chamber for addition of heat for startup and removal  of heat when
the oxidation commences and excess heat is generated.

     The process should show much lower capital investment and much lower
operating cost than an above-ground wet oxidation plant.  More usable surplus
thermal energy should be generated.  The principal drawback is the inaccess-
ability of the equipment.  If anything goes wrong, it is a major task to fix
it.

     Another presentation at this symposium will explain in more detail the
proposed VTR installation at Longmont, Colorado.  Consequently,  it will not be
discussed further here.  The EPA is planning to assist in the installation of
the Longmont facility and is supporting the costs of an operation and evalu-
ation period.  This process holds great promise for many areas of the country,
particularly those where geology is favorable for well drilling.

SOLID PRODUCTS

Drying

     The simplest thermal process for producing a solid product  from sludge is
thermal drying.  The dried product is accepted as a fertilizer,  and, in the
users' mind, no longer has a "fecal connection."  If metals and  organic con-
taminants are low, sludge makes an acceptable fertilizer.  The main drawback
is the cost to evaporate the water from the sludge cake.  There  has been a
great revival of interest in removal of water by the Carver-Greenfield process
in which sludge is dewatered as it is carried by an oil through  a multiple-
effect evaporator.  This process was evaluated by the City of Los Angeles  as
part of the LA/OMA (Los Angeles, Orange County Metropolitan Area) sludge dis-
posal research program for possible use in one of their processing plants
(9).
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     Operation demonstrated good thermal efficiency, low loss of carrier oil,
and few operating problems.  As a result of this work, both the City of Los
Angeles and the Los Angeles County Sanitation Districts plan to use this pro-
cess in their processing scheme (9).  Both authorities plan to dewater the
sludge to dryness by this method, to be followed by starved-air combustion of
the dried sludge in multiple hearth furnaces.

     The Carver-Greenfield process needs no further development.  Evaluation
of results when the Los Angeles plants come on stream is appropriate.

Manufacture of bricks

     The author has heard over the course of several years suggestions that
sludge be used in processes that require water, for example, casting concrete
foundations.  The user would receive a credit close to the dewatering cost of
sludge which would reduce cost of manufacture.  The important concern is that
the sludge must not degrade the quality of the product.  Most of these sug-
gestions have not become a reality because of concerns about degradation of
product quality.  Recently, the National Science Foundation has funded an
investigation by Dr. James Allamen, University of Maryland, to determine the
effect of sludge addition on quality of brick.  Dr. Allamen's investigation so
far indicates a reduction in strength and a reduction in density as sludge
content increases.  The investigation is continuing and will perhaps disclose
conditions where sludge addition will produce a competitive product.

Manufacture of aggregate

     For several years, the Franklin Institute Research Laboratory (FIRL) in
Philadelphia has been developing a method called the Ecorock process for pro-
ducing an aggregate suitable for an asphalt hot mix used for road construction.
They have thermally processed the residue from solid waste incineration into
an aggregate and submitted it to the U.S. Department of Transportation for
tests,  which included testing in actual use on highways.  The material was
rated very highly in all tests.  The EPA has supported experiments to deter-
mine whether sludge cake could be included in the aggregate.

     The basic Ecorock process is shown schematically in Figure 4.  Sludge
cake is introduced into the dryer along with coarsely ground incinerator
residue.   Drying and burnout occur in two separate rotary kilns.  Temperature
reaches 1700 °F in the burnout kiln.  Further elevation in temperature to 2200
°F occurs in the fusion furnace.  The resultant fused product is cooled and
crushed to the desired size.

     Bench scale experiments were conducted to determine the effect of sludge
cake on the properties of the Ecorock.   The most difficult step in this research
was obtaining a representative sample of incinerator residue.   Results of the
tests are shown in Table *!.  From the table, it appears that ratios of sludge
to residue up to 0.4:1 produce a suitable aggregate.

     A large pilot facility capable of processing, on a dry weight basis, 28
tons per day of solid waste residue (82% solids) and 20 tons of sludge cake
(20% solids) has been built at Philadelphia's Northeast Sewage Treatment Plant.

                                     676

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   SOLID WASTE
   RESIDUE FEED   (A)
                     ROTARY DRUM SCREEN
                              (B)
AIR POLLUTION
CONTROL SYSTEM
(K)
cr»
                                         TEMPERING AIR
                                                 (E)
         (SLUDGE AS CO-FEED) (J)	
                    FUSION FURNACE
                    (F)
                      AUXILIARY BURNER
                           (G)
                                AIR COOLED AGGREGATE
                                TO CRUSHING (H)
       FIGURE 4.  RESIDUE FUSION  PROCESS INCORPORATING SEWAGE  SLUDGE DISPOSAL (Moo II).

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      Table 4.  Summary of Mixing, Handling, Drying, Burning and Fusion
                 Experiments on Wet Sludge/Incinerator  Residue  Mixtures
Sludge/Incinerator Residue*

     Wet Ratio    Dry Ratio

    Pure sludge
       10/1
        5/1
  2/1
  1/1
        4/1

        3/1
0.8/1

0.6/1
        2/1
        1/1
0.4/1
0.2/1
                 Observations

Pasty solid dried into a hard cake.  Burned
with considerable odor and smoldering from lack
of air.  Aggregate formed at 2,000 °F was light
weight and of very low strength.

Wet mixture resembles and handles like pure
sludge.  Ecorock may be acceptable as a light
weight low strength aggregate.

The presence of incinerator residue is barely
apparent in the wet stages.  Smoldering
occurred when burnout was occurring.  Dusty
appearance during final burning stages. Fused
aggregate appears hard.

Approximately the same as above.

Wet mix tumbles and flows because of the
presence of incinerator residue.  No smoldering
during burnout.  High concentration of residue
readily fuses with sludge ash during fusion.
Aggregate looks very good; hard, tough, and
uniform.

Mixing, flow, drying, burnout and fusion
proceeded as well as with pure  incinerator
residue.

Same as above.
*Sludge at 20$ solids

Plans are to start operation in fiscal year 1982.
in evaluating the process.

A LOOK INTO THE FUTURE
                                 EPA will join with the City
     In the next few years, the pressure to modify and improve incineration
practice, particularly with respect to particulate removal and fuel economy,
will continue.  It is expected that many installations will modify their
existing facilities to the starved-air combustion mode using extra dry sludge
cake or supplemental fuel addition.
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     Coincineration will make slow progress,  primarily because solid waste
incineration is making slow progress.   We need showplaces that demonstrate
that incineration of solid waste is not a messy,  polluting operation.

     Conversion of sludge to liquid fuel might be used at the largest sewage
treatment plants.  Information on the  effect  of scale of operation on economics
is needed.  More developmental work is needed before this kind of information
can be developed.  Consequently, it is not possible to predict the future of
such processes yet.  Because developmental work is expensive, and the "universe"
of plants that might use the process is small, efforts will be made to limit
development work to a single outstanding candidate process.

     It is not expected that processes like the Ecorock process or deep well
oxidation can be used everywhere, but  they appear to have a place.  Within
a year or two, firm information should be available on the potential of these
processes.

     One thing can be stated with assurance.   Thermal conversion will  remain
an important disposal option for sludge, but  existing procedures will see
radical change.

ACKNOWLEDGMENTS

     The assistance of Dr. Atal Eralp  and Mr. Howard Wall in assembling materi-
al for this presentation is gratefully acknowledged.  The work reported is
primarily the work of EPA grantees and contractors.  Their contributions are
also sincerely appreciated.
                                     679

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REFERENCES

1.   Ottman, R.  D.,  Bergstedt,  D.  C.,  Stulc,  D.  A.,  and Swanson,  G.  J.,
     "Coincineration of sewage  Sludge  with Coal  or Wood Chips,"  Draft Report
     to U.S. EPA,  to be made available through N.T.I.S.

2.   Brown and Caldwell Engrs., for Central Contra Costa Sanitary District,
     "Solid Waste  Resource Recovery Full-Scale Test Report,  Vol.  1,  Mar.  1977.

3.   Cosulich, W.  F., "Codisposal  of Refuse and  Sludge," Public  Works,  pp.  66-
     69 (August 1980).

M.   "Hempstead Facility Seeks  Backing," Inside  E.P.A.  Weekly Report, 2,  No.
     34, p. 1 (Aug.  21, 1981).

5.   McDonald, G.  C., Quinn, T.,  and Jacobs,  A., "Sludge Management  and Energy
     Independence,"  Jour. Water Pollut.  Cont.  Fed.,  !53, 190-200  (Feb. 1981).

6.   Arbo, J. C.,  Glaser, D. P.,  Lipowicz, M.  A.,  Schulz,  R.  B.,  and Spencer,
     J. L., "Adaptation of the  Simplex Gasification Process  to the Co-Conver-
     sion of Municipal Solid Waste and Sewage Sludge,"  ERDA  Report 81-6,  Apr.
     1981, submitted as draft report to U.S.  EPA.

6a.  Vigil, S. A., and Tchobanoglous,  G.,  "Thermal Gasification  of Densified
     Sewage Sludge and Solid Waste," presented at 53rd  Water Pollut. Cont.
     Fed. Conf.,  Las Vegas,  Oct.  2, 1980.

6b.  Bartley, D.  A., "Investigation of the Economic Feasibility  of Disposal of
     Sewage Sludge by Co-Gasification  with Source-Separated  Waste Paper," M.S.
     Thesis, University of California, Davis,  Calif., 1980.

7.   Burns, Roger, G.,  Jr.,  oral  communication,  Sept. 1981.

8.   Cadotte, A.  P., and Laughlin, R.  G. W.,  "Waste Destruction  with Energy
     Recovery:  the  WETOX Process," in "Water Pollution Control  Technologies
     for the 80's,"  ed. Schmidtke, N.  W.,  and Eberle, S. W.,  Proc. of First
     Canada/Germany  Wastewater  Treatment Technology Exchange Workshop,  Canada
     Centre for Inland Waters,  Burlington, Ontario,  Oct. 3-5, 1979.

9-   Vol. 1, Draft Environmental  Impact Statement/Environmental  Impact Report,
     "Proposed Sludge Management  Program for the Los Angeles/Orange  County
     Metropolitan  Area, Draft Facilities Plan/Progarm (April 1980).
                                     680

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TECHNOLOGY ASSESSMENT OF THE VERTICAL WELL CHEMICAL REACTOR
                             by
           John M. Smith* and Jeremiah J. McCarthy**
                Wastewater Research Division
        Municipal Environmental Research Laboratory
            U.S. Environmental Protection Agency
                   Cincinnati, Ohio 45268
     This paper has been reviewed in accordance with
     the U.S. Environmental Protection Agency's peer
     and administrative review policies and approved
     for presentation and publication.
                Prepared for Presentation at:
              8th United States/Japan Conference
                              on
                 Sewage Treatment Technology
                         October 1981
                       Cincinnati, Ohio

                             681

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          TECHNOLOGY ASSESSMENT OF THE VERTICAL WELL CHEMICAL REACTOR

                   John M. Smith* and Jeremiah J. McCarthy**
                        Urban Systems Management Section
                  Municipal Environmental Research Laboratory
                      Office of Research and Development
                      U.S. Environmental Protection Agency
                             Cincinnati, Ohio 45230
ABSTRACT
     The vertical well chemical reactor (VWCR) is designed to oxidize high
strength organic wastes using wet combustion principles.  Its vertical concen-
tric configuration uses little space compared to above ground wet oxidation
vessels and promotes efficient heat exchange.  Natural pressurization from the
weight of the liquid above results in safer, more economical operation.  Full
size reactors are expected to extend to 6000 foot depths underground and operate
at maximum temperatures and pressures exceeding 650°F and 1500 psi respectively.

     COD reductions of waste sludges have approached 50 percent at pilot scale.
Eighty percent reductions are expected for full scale where deeper wells will
be drilled and higher temperature and pressures attained.  The fate of metals
in the VWCR including distribution within the particulate and soluble wastewater
fractions for various oxidation conditions is not well understood and more work
needs to be done in this area.

     Construction is to begin late 1981 on a full scale sludge demonstration
VWCR plant at Longmont, Colorado.  Major operational items to be addressed
(based on pilot plant experience) include pit corrosion, scale formation, and
leaking joints.

     The VWCR is a potentially desirable treatment process which can stabilize
organic wastes, significantly reduce sludge volume, oxidize toxic materials,
kill pathogenic organisms, and permit energy recovery from high strength wastes.


INTRODUCTION

     The vertical well chemical reactor (VWCR) is designed to oxidize high
strength organic wastes using wet combustion principles.  If sufficient air
(oxygen), temperature and pressure are present, organic substances can be
oxidized in a liquid state.  The oxidation reaction proceeds exothermically
and if organic content of the waste is high enough, combustion may be thermally
self-sufficient and even produce energy as heat.

     Figure 1 is a process flow diagram showing a vertical section of the VWCR.
Two concentric tubes constructed from 300 series stainless steel serve as the
reactor vessel.  They are surrounded by a liquid filled heat exchange jacket
which can independently add or remove heat to maintain the required temperature.
*J. M. Smith and Associates PSC, Consulting Engineers, 7373 Beechmont Avenue,
Cincinnati, Ohio 45230
**U.S. Army, 10th Medical Laboratory, APO New York, 09180
                                      682

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Air is also injected at several downcomer locations along the waste fluid path.
It assists fluid flow and provides oxygen for oxidation.  Insulation to minimize
heat losses within the reactor and to the surrounding earth completes the basic
VWCR design.

     Waste is introduced into the downcomer tube at the earth's surface.  As it
flows downward, effective wet oxidation begins at 350°F and continues as tem-
perature and pressure increase to their maximum.  Upflowing oxidized waste is
gradually cooled as it transfers heat to the downflowing fresh waste.  Any
excess heat which may result from the exothermic oxidation reactions is removed
by the heat exchange jacket.

     The VWCR is designed with no moving parts below ground level and needs no
high pressure vessels.  Its components below the surface are the stainless steel
downcomer and upcomer concentric reactor tubes, air lines, heat exchange jacket,
and associated temperature thermistors and pressure measuring devices.  The
reactor tubes are subject to the potential scaling and corrosion characteristic
in any high temperature and pressure liquid environment.  VWCR operation effi-
ciency, in addition to design and waste composition considerations, is dependent
on the reliability and accuracy of downhole measuring equipment and on the heat
exchange efficiency between the fresh and oxidized waste.


DEVELOPMENT STATUS

Laboratory Bench Scale Research

     Initial laboratory scale testing began in 1973 by the Vertical Tube Reactor
Corporation, Englewood, Colorado.  A 2.7 liter stainless steel laboratory batch
reactor employing similar temperature conditions upon which a full scale VWCR
is based was used to oxidize organic materials over a wide range of COD concen-
trations.  Under EPA/MERL sponsored research since 1979, primary and secondary
sludges from several municipal wastewater treatment plants have been oxidized
in the laboratory reactor.

     Batch reactor tests using municipal wastewater have been run on wastewater
from Montrose, Colorado.  Montrose wastewater contains a high portion of indus-
trial (candy) wastes which range from 200-2500 mg/1 COD in strength.

     For municipal organic wastes without a significant refractory component,
it has been found that the extent of COD reduction is primarily a function of
reactor operating conditions and less a factor of specific waste make-up.
Figure 2 summarizes general COD removal experience using the laboratory reactor
while oxidizing both high COD wastewater and sludge.  General trends are sum-
marized in Table 1.  These trends generally agree with pilot and full-scale
studies reported in the 1960's by investigators using conventional above-ground
pressure vessel equipment for wet oxidation (1).

Pilot Scale Research

     A VWCR pilot plant has operated intermittently since 1977 at Lowry Bombing
Range, near Denver, Colorado.  It consists of a stainless steel 1-3/4 inch down-
comer and 2 inch diameter upcomer within a 2-1/2 inch reactor casing.  The
reactor casing, air line, heat exchanger lines and insulation are all suspended
in a 5-inch, 1500 foot standard American Petroleum Institute well casing.


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     Most pilot scale effort has concentrated on solving structural, mechanical
and other operational problems.  Pit corrosion and scale formation, heat exchange
line plugging, reactor-heat exchanger interface design, and leaking joints were
the major engineering problems encountered.

     Table 2 presents a summary of municipal sludge COD reduction data from the
pilot plant tests and compares them to batch reactor results under similar opera-
ting conditions.  The close pilot and batch treatability results experienced
under similar operating conditions has supported the use of a laboratory batch
reactor to model pilot plant treatability expectations.  Limited solids, metal
and off-gas data have also been taken during pilot studies.  More measurements
need to be made on these parameters before conclusions can be made.

Full Scale Research

     EPA's Office of Research and Development recently received a preapplication
for federal assistance from Longmont, Colorado to build and evaluate a VWCR to
treat its sludge.  The Longmont wastewater treatment plant is a secondary bio-
logical process treatment plant with flow equalization and anaerobic sludge
digestion.

     The proposed VWCR for Longmont has an 8 inch nominal diameter reactor casing
to be suspended 6000 feet.  It will operate at temperatures of 500 to 650°F, in-
fluent diluted sludge strengths of 5,000 to 10,000 mg/1 COD and reaction times of
25 to 100 minutes.  Oxidation efficiency is expected to be 75 percent.  Figure 3
shows the proposed Longmont process schematic.

     The overall objective of the Longmont program is to demonstrate technical
and economic feasibility of a full scale VWCR for oxidation of municipal sludge
and selected industrial wastes.  The program involves three basic phases over
at least two years.  Phase I includes design, construction and initial operation
of the VWCR at Longmont.  Phase II is designed to provide long term reliability
and operating information about processing municipal sludge.  It will also evalu-
ate the impact of sludge treatment with the VWCR on the other Longmont wastewater
treatment plant operations.  Phase III will investigate treatment and disposal of
complex industrial wastes.  In addition, an energy recovery system will be de-
signed to convert excess combustion heat into usable energy for treatment facility
use.  During all phases, system components will be monitored for energy efficiency,
operation and maintenance characteristics, and material durability.


TECHNOLOGY EVALUATION

Theory

     The VWCR process utilizes the fact that any burnable substance can be oxi-
dized in the presence of liquid water and sufficiently high temperatures and
pressure.  Oxygen for the VTR oxidation process is supplied by air.

     Wet oxidation is the result of at least three chemical reactions:  (1)
heterogeneous (two-phase) oxidation; (2) hydrolysis; and (3) liquid phase oxi-
dation.  Initially, destruction of the solid organic waste is predominantly the
result of heterogeneous (two-phase) oxidation by direct contact between adsorbed
oxygen gas and organic solids.  At elevated temperatures, the solids are quickly
reduced to simpler organic colloids by hydrolysis.  Hydrolysis will split organic
polymers from the colloidal or soluble organic matter but will not destroy them.

                                      684

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Ultimate destruction of the organic matter is by liquid phase oxidation, i.e.,
wet oxidation following individual collisions and interactions between absorbed
oxygen and organic compounds in solution.

     Wet oxidation reactions are exothermic and release energy as heat.  The
quantity of heat released depends on waste make-up.  If the heating value (pro-
portional to organic strength) of the waste is high enough, the temperature
required for oxidation can be sustained by oxidation itself.

     The liquid in the reactor cannot be allowed to vaporize and change into
the gaseous phase.  The maximum allowable temperature of the waste is just be-
low the boiling point of the liquid.  This temperature depends on the pressure
of the liquid's saturated vapor.  Pressure down hole in the VWCR is in turn a
function of weight or head of liquid above it.  Thus, the maximum allowable
temperature in the VWCR varies with depth and roughly follows the saturated
vapor pressure - temperature curve relationship for water.

     In summary, four important parameters control performance of the wet oxi-
dation process:  feed solids concentration, pressure, temperature and air supply.
The COD test is normally used as a measure of process efficiency.  Average wet
oxidation efficiency is 70-90% COD reduction.  Some organic matter in the lorm
of low molecular weight compounds such as organic acids, aldehydes and acetates
will be observed in the effluent.  Final oxidation products are highly dependent
on the degree of oxidation and composition of the waste.

Process Capabilities and Limitations

     Because it is not necessary to supply energy for the latent heat of vapor-
ization, wet air oxidation is particularly applicable to oxidize organic sludges
which can supply some or all of the heat required to maintain combustion tempera-
tures but cannot be separated readily from water.  The concentric tube configura-
tion of the VWCR is naturally conservative and is conducive to good heat transfer
because of tube proximity.  Furthermore, once the surrounding earth reaches equi-
librium, it may act as a heat envelope and buffer external temperature variations.

     Like many high temperature - high pressure processes, corrosion and scale
formation in the reactor and heat exchange surfaces are inherent problems with
the process.  Measures such as repassivation of the stainless steel surfaces
with an acid can be taken to minimize corrosion and deposition.  The extent of
scaling and deposition and the degree to which it can be controlled is yet to
be characterized for the VWCR.

     Compactness of the VWCR configuration makes down hole maintenance and re-
placement difficult.  Delays in pilot operation to date have come from diffi-
culties in replacing components which, for various reasons, had to be changed
or redesigned.  Experience gained during pilot scale testing will be applied to
full scale design at Longmont, hopefully to minimize engineering problems.

     Oxidation using the VWCR may provide a good approach for treatment of toxic
and hazardous wastes, landfill leachates in particular.  In independent but re-
lated laboratory tests, wet oxidation using a moderate (527°F) and high (608°)
temperature has been demonstrated to be an excellent method for destroying and
detoxifying certain organic compounds including phenols, acrolein, dinitrotoluene,
and diphenylhydrazine (2).  Other laboratory tests have indicated that virtually
all organic substances can be completely solubilized and broken down ("reformed")

                                     685

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to low to medium molecular weight compounds in supercritical water (above 705°C
and 220 atm)(3).  Subsequent rapid and complete oxidation of the reformed pro-
ducts is expected but just beginning to be tested under these supercritical
conditions (4).  The fluid which exists under supercritical conditions is neither
a liquid or a gas and has a density of only 0.2-0.5 g/m^.  Thus, much of the
natural hydrostatic head of the VWCR would be lost when operating in a supercriti-
cal regime and the reactor would have to be pressurized.

Design Considerations

     Mathematical models simulating thermodynamic conditions within the reactor
have been developed to be used with wastewater treatability results to design a '
VWCR:

     Hydrodynamic Analysis;  Flow velocities, temperatures, and pressures at
     various down hole locations are estimated from given waste treatability
     data, VWCR physical dimensions, heat exchange properties, and desired
     reaction temperatures.  VWCR size and depth options are considered from
     this model.

     Heat Flow Analysis;  Heat loss from the VWCR to the surrounding earth is
     estimated as a function of time and reactor geometry and insultation.
     Heat exchanger design criteria is established from this model.

     Heat Exchanger Analysis:  Heat loss from heat exchanger lines to the earth
     is estimated as a function of reactor geometry, operation, and insulation.
     Net energy surplus from (or required energy input to) the heat exchanger
     fluid serving the VWCR is estimated from this model.

Verification of model predictions should come from demonstration plant operation
at Longmont.

     When considering feasibility of a VWCR, a subsurface geological investiga-
tion is necessary both to determine expected well drilling costs and to estimate
the surrounding earth's thermal and structural properties.  A geophysical survey
of available sources of data can provide much information.

     Precautions must be taken to minimize effects of corrosion and deposition.
A weekly nitric acid passivation operation has been recommended.  The effect of
down hole temperature and pressure as well as the influence of acid addition on
wastewater treatment efficiency is not known at this time.  The most desirable
procedure for acid addition over long term VWCR operation will be developed
during demonstration plant operation.

Energy Considerations

     In the absence of other data, a value of 6,000 BTU/lb COD oxidized can be
used to estimate the heat value of a waste.  Energy considerations are best
illustrated by example:

     Consider a 10 mgd plant producing 10 tons dry sludge daily.

     Assuming wet sludge consists of  5 percent solids the:
          10 x  2000 x I/.05 = 4 x 105 Ibs wet sludge produced daily


                                      686

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     Assuming further that 20% of its heat is lost to the surrounding earth then:
          6000 x  (1.0-0.2) = 4800 BTU/lb COD effective heat value

     For an influent/effluent temperature differential of 5°F, and a specific
     heat of 1 BTU/lb mass °F, the heat loss Q = MCAt is:
          4 x 105 x 1 x 5 = 20 x 105 BTU/day

     The COD required to be oxidized to make up this heat loss assuming 75%
     of the COD is oxidized in the VWCR is:
          4 x 105/(4800 x .75) = 556 Ib COD oxidized/day

     Thus, for steady state conditions where heat losses just equal heat
     production through the VWCR, COD of the sludge must be at least:
          556/4 x 10^ = 1390 ppm or mg/1 for thermal self sufficiency

     This example well illustrates how several variables can affect calculations
estimating the COD concentration required for thermal self-sufficiency of the
waste.  Note that the sludge solids concentration, specific heat of sludge, heat
loss, percent sludge oxidation and influent/effluent temperature differential
were assumed.  If, for example, the temperature differential had been 2°F, the
mg/1 COD required for thermal self-sufficiency would have dropped to 556 mg/1
COD for the waste.  It is also important to keep in mind that the example
assumes sufficient conditions already exist in the reactor for oxidation to
proceed.  That is, initial heat to bring the reactor up to the required oxi-
dation temperature has been supplied, there is sufficient air for oxidation,
and there is sufficient pressure in the reaction zone for the liquid reaction
to proceed at the required temperatures.

Operation and Maintenance Requirements

     Operation and maintenance requirements for full size VWCR treatment have
been estimated based on pilot plant experience.  Major labor expenditures are
for pump and valve maintenance, coarse screen cleaning, and sludge disposal.

     Structures and reactor casings, as well as air and heat exchange lines,
are estimated to have a 40 year life.  Mechanical/electrical equipment is esti-
mated to last 15 years.  The stainless steel upcomer and downcomer are con-
servatively estimated to have a 10 year life.  Their life span will utlimately
depend on the extent and controllability of corrosion and deposition experi-
enced.  Nitric acid qualities and acid wash operation have yet to be determined.
This is one of the most important areas to be investigated at the Longmont VWCR
demonstration plant.

     Unlike most existing wet oxidation processes which operate at low to inter-
mediate wet oxidation levels, VWCR operation is expected to provide a high degree
of wet air oxidation.  It is expected that liquor strength will not be as great
as that from heat treatment processes which do not stabilize the waste to such
an extent.  Similarly, odor treatment is not expected to be a significant design
factor for such high degrees of sludge oxidation.


ASSESSMENT OF NATIONAL IMPACT

     The vertical well chemical reactor employs chemical oxidation to oxidize
organic materials in water solution or suspension.  In general, the desirability


                                     687

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of using a VWCR is influenced by plant size, site-specific geological conditions,
wastewater characteristics and sidestream treatment.

     It is estimated that VWCR can be a competitive process for wastewater treat-
ment plants of size 20 mgd and larger.  Well drilling costs will normally con-
stitute the single largest capital outlay item.  Thermal self-sufficiency depends
largely on the actual temperature differential between influent and effluent.
The VWCR will most likely be applied to oxidation of municipal sludges.  The
high degree of oxidation expected from the VWCR is expected to stabilize liquor
and odor sidestreams to a great extent.  Refractory components in liquor side-
streams need to be measured.

     In summary, the VWCR is a technology for treating organic wastes which can
significantly reduce sludge volume, toxic materials, or pathogenic organisms,
or provide the potential for energy recovery from high strength wastes.


CONCLUSIONS AND RECOMMENDATIONS

     1.  Configuration of the VWCR has both advantages and disadvantages:

         a.  The VWCR uses little space compared to above ground wet oxidation
     configurations;

         b.  The concentric tube configuration promotes efficient heat exchange
     between influent and effluent streams;

         c.  The vertical tube configuration allows natural pressurization of
     the waste from weight of the liquid above it.  The below ground natural
     pressurization is safer, simpler and cheaper than above ground mechanical
     pressurization; however, it is less flexible.  Pressure at any point
     down-hole in the reactor is relatively constant, and therefore, the maximum
     allowable temperature (not exceeding the waste boiling temperature) is fixed
     for any depth, approximately following the saturated vaporization curve
     for water;

         d.  Reactor tube size limits the amount of air which can be added to
     support oxidation.  Standard operating procedure involves sludge dilution
     to meet maximum air and temperature limitations; and

         e.  VWCR configuration and compactness make down-hole accessibility
     difficult.  Mechanical reliability and maintenance of the VWCR system are
     important considerations.

     2.  Appropriate bench or pilot scale treatability tests using the waste to
be oxidized are very important.  The degree and rate of waste wet oxidation is
significantly influenced by temperature and pressure.  Temperature and pressure
requirements affect VWCR dimensions and ultimately costs.

     3.  COD reduction experienced using a batch laboratory reactor has been
close to that obtained at pilot plant scale under similar operation conditions.
This supports the use of a bench scale reactor to model pilot COD reduction
rates.   Experience with the fate of metals or toxics is less definite and more
study needs to be undertaken in this area.


                                     688

-------
     4.  The VWCR is especially applicable to wastes having a high organic con-
tent so that a thermally self-sustaining reaction can be maintained.  The mini-
mum organic concentration for autothermal conditions will depend largely on the
actual temperature differential between influent and effluent wastes.

     5.  When considering the feasibility of a VWCR, a subsurface geological
investigation is necessary to identify aquifers, estimate well drilling costs,
and determine the earth's thermal properties.

     6.  Sludge stabilization trends using a laboratory reactor designed to
simulate VWCR oxidation conditions generally agree with historical above ground
pilot and full scale wet oxidation observations which indicate that as pressure
and temperature increase:

         a.  The rate and extent of COD reduction increases;

         b.  The particulate waste fraction approaches an inert, readily
     settleable ash; and

         c.  The soluble waste fraction becomes more biodegradable.

     7.  The VWCR is not yet fully developed in that all process variables
normally expected in full scale application have yet to be characterized.

         a.  The efficacy of the acid wash system to control reactor sealing
     and corrosion has yet to be demonstrated;

         b.  Verification of heat transfer and heat flow models which influence
     VWCR design and predict energy surplus or deficits is not complete; and

         c.  Long term operation at thermally self-sufficient conditions has
     not been carried out.  Such operation will help define realistic opera-
     tional variables and maintenance requirements.
                                     REFERENCES
1.  Hurwitz, E., G. H. Teletzke and W. B. Gitchel, "Wet Air Oxidation of Sewage
    Sludge," Water and Sewage Works, Vol. 112, No. 8, August 1965, pp. 298-305.

2.   Randall, T. L. and P. V. Knopp, "Detoxification of Specific Organic Sub-
     stances by Wet Oxidation," JWPCF, Vol, 52, No. 8, August 1980, pp. 2117-
     2130.

3.   Amin, S., R. C. Reid and M. Modell, "Reforming and Decomposition of Glucose
     in an Aqueous Phase," Inter. Soc. Conference on Environmental Systems, San
     Francisco, CA, July 21, 1975.

4.   Olexsey, R. A., Issue Paper on Supercritical Fluids Processing for Hazard-
     ous Waste, EPA/IERL Internal Memorandum, Cincinnati, Ohio, June 1980.

5.   Effects of Thermal Treatment of Sludge on Municipal Wastewater Treatment
     Costs, EPA-600/2-78-073, Municipal Environmental Research Laboratory,
     Cincinnati, Ohio, June 1978.

                                      689

-------
Table 1.  Waste Stabilization Trends Using Laboratory Reactor Data


 •   The extent of COD reduction significantly increases with
     temperature up to at least 600 °F.

 •   Increasing batch reaction time from 1/2 to one hour effects
     about 10 percent greater COD removal at 400 °F and approaches
     no difference at 650 °F.

 •   The particulate (ash) COD decreases to almost zero about 600 °F
     confirming expectations of an inert ash.

 •   The portion of effluent BOD remaining (as a fraction of total
     COD) increases with reaction temperature indicating the
     refractory reactor effluent is mostly biodegradable for the
     wastes tested.
                                 690

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                                         Table 2

                                     A Comparison of
                      VWCR Pilot Plant and Laboratory Batch Reactor
                                   COD Reduction Data


Flow Rate
Test Dates Gal/Min
July 24-25,80
Sept 11-22
Nov 6-21
Dec 7-16
Dec 20-23
Mar 19-23,81
Mar 20
Mar 23
4.0
4.1
4.2
4.5
4.5
4.5
4.5
4.5

Reaction
Time Min*
30
25
25
20
20
28
28
28
Bottom
Reactor
Temp °F
440
400
420
440
420
500
500
510
Influent
COD
MG/L
350
100
740
600
880
1,340
1,110
1,063
Effluent
COD
MG/L
248
73
548
468
695
784
657
567
Pilot Plant
COD
Reduction
%
29
27
26
22
21
45
41
47
Laboratory
Reactor COD
Reduction, %
28
18
24
22
22
51
—
51
^Estimated time that sludge was  above 350 F while flowing through  pilot  plant.

-------
            Table 3.   Preliminary Life Cycle Cost Estimate for a VWCR
                      System Containing an Eight Inch Diameter Reactor*


Project Capital Costs (and expected service life)                  $  600,000
     Well drilling and casing (40 yr)
     Vertical well chemical reactor
         - reactor heat exchange lines, air lines and
           casing (40 yr)                                          $  300,000
         - reactor upcomer and downcomer (10 yr)                   $  300,000
     Mechanical/electrical equipment (15 yr)                       $  300,000
     VWCR building (40 yr)                                         $   40,000
     Existing WWTP modifications to accommodate VWCR               $   60,000
                                       Construction Cost           $1,600,000

     20% drilling contingencies                                    $  320,000
     20% non-construction costs (engineering, supervision, etc)    $  320,000
                                       Total Capital Cost (PW)     $2,240,000

Replacement Costs
     Reactor upcomer and downcomer ($300,000 x .50245) -           $  151,000
     Mechanical/electrical equipment ($300,000 x .35615) -         $  107,000
                                Total Replacement  Costs (PW)      $  258,000

Salvage Value
     Well drilling and casing 20/40 (600,000 x .25245) -           $   76,000
     VWCR heat exchange lines, air lines and casing
       20/40 (300,000 x .25245) =                                  $   38,000
     Mechanical/electrical equipment 10/15 (300,000 x .25245) -    $   50,000
     VWCR building 20/40  (40,000 x .25245) -                       $    5,000
                                           Salvage credit (PW)     ($  169,000)
Operation and maintenance costs
     $154,250 x 10.49186                                           $1,618,000
     Total Present Worth                                           $3,947,000
     Equivalent Annual Costs  ($3,952,000/10.49186)                 $  376,OOO/
     *See Figure 3 for definition of system components.
      The VWCR system is sized to treat sludge generated by a 7.5 mgd WWTP.
      Discount rate » 7-1/8%; 20 year life cycle period.  Potential
                      energy recovery credits are not included in O&M.
                                       692

-------
                                                             REACTOR INFLUENT (DOWNCOWER)
          DOWNCOMER
START OF REACTION ZONE
              MOV
   HEAT EXCHANQER Oft.
   •OTTOM OF REACTOR
   TEMPERATURE VARKS
                                                                 NOT TO SCALE
         Figure 1.   Typical  vertical well chemical reactor profile.
                                        693

-------
             80 MINUTES REACTION TIME
                                 t sf  30 MINUTES REACTION TIME
                        IS MINUTES REACTION TIME
                        REACTION TEMPERATURE, °F
Figure 2.  Typical COD reduction versus reaction temperature
                  and time using laboratory reactor data.
                                694

-------
 SLUDGE-
                                        LONGMONT
                                        PROCESS FLOW SCHEMATIC
         I    SRINOER      SUXMC PUMP  J

         SLUDGE CONTROL BUILDING ~~
              -FLOW METER

        serrueo
        (FFLUCNT
        PUMP
                                                   VTR FEED PUMP
                     PLANT
                     SERVICE
                     WATER
Tl


)
L-

R

J

«>-

-txl



-1 MILEf
SOILED
FEED
PUMP
-T2-





^



*-0

^


\
<-




f
'


— +-





f.


b
^
r>
                ASH TO
                SLUOOf
                     VTR STTTXED EFFLUENT
                     RCTURNtO TO HEAOWORKS
                     •COS
                            ASH PUMP
Figure 3.   Proposed Longmont  VWCR process  flow  schematic.
                                 695

-------

-------
FLOW MANAGEMENT BY POROUS PAVEMENT AND INSITUFORM CONTROL OF INFILTRATION
      Carl A. Brunner, John N. English, and Robert B. Turkeltaub
                Systems & Engineering Evaluation Branch
             Municipal Environmental Research Laboratory
                 U.S. Environmental Protection Agency
                           Cincinnati, Ohio
            This paper has been reviewed in accordance with
            the U.S. Environmental  Protection Agency's peer
            and administrative review policies and approved
            for presentation and publication.
                     Prepared  for Presentation at:
                   8th United States/Japan Conference
                                   on
                      Sewage Treatment Technology

                               October 1981
                             Cincinnati, Ohio


                                    697

-------
 FLOW MANAGEMENT BY POROUS PAVEMENT AND INSITUFORM CONTROL OF INFILTRATION

         Carl  A.  Brunner,  John N.  English,  and  Robert  B.  Turkeltaub
                  Systems & Engineering Evaluation Branch
                Municipal Environmental Research Laboratory
                    U.S.  Environmental  Protection Agency
                              Cincinnati, Ohio
ABSTRACT

     The runoff from large paved urban areas and the infiltration of storm-
water into sanitary sewers both can constitute large volumes of polluted
waste. These wastewaters either cause environmental problems directly from
discharge to receiving waters or indirectly by overloading sewage treatment
plants and interfering with proper operation.  Porous pavement provides a
possible solution for reducing or totally eliminating the runoff from parking
lots and low traffic volume streets.  Insituform is a novel method for
rehabilitating leaky sewers that has the potential for a much higher degree
of infiltration reduction than has been possible using more conventional
methods.
STORMWATER MANAGEMENT BY POROUS PAVEMENT

Urban Stormwater Problem

     Urbanization produces significant changes in the hydrologic character-
istics of a watershed that can result in two major problems, flooding from
increased runoff and water quality degradation.  Consequently, various
communities have enacted legislation which allows no increase in runoff
rates, or water quality degradation beyond pre-developed conditions.

     Stormwater management has generally consisted of collecting all the
runoff in a conveyance system of sewers and channels which are tributary to
a nearby receiving water.  High peak flows result, however, which can create
severe flooding problems downstream.  In addition, impervious areas generate
urban pollution that is difficult to control because they do not have capa-
city to assimilate pollutants.  The major method to control runoff excess
is the use of detention and retention ponds.  In areas where a number of
contiguous impervious surfaces exist or are planned, the use of porous
pavement to restore the infiltration and storage capacity of an urban water-
shed becomes a viable flow and pollutant control alternative.

Porous Pavement as a Control Technique

     Porous pavements provide storage that can be used to reduce runoff to
preurbanization levels.  They capture the initial runoff or "first flush"
volume, which most studies indicate to be the most degraded in terms of
                                     698

-------
pollutant concentrations,  and most of the  subsequent flows which are likely
to be less polluted.

     Porous pavements may be used in areas that are already urbanizeds  such
as downtown areas of most cities, as well as in existing suburban shopping
centers where the storm sewer network was installed prior to excessive
impervious cover development.  Under these conditions,  the storm sewers may
become overloaded and the disposal of excess runoff becomes a problem that
porous pavements could solve.  This benefit is enhanced in areas with combined
sewerage because the probability of the sewer overloading and the resultant
discharge of raw sewage into the receiving waters is reduced.

     In areas being developed, porous pavement has the potential for re-
ducing both storm sewer requirements and the volume of runoff.

     If the stormwater requires treatment, it may be stored in porous pave-
ment systems isolated from the natural ground by an impermeable membrane
until the treatment plant capacity becomes available.  Thus, treatment
plant capacity does not need to be expanded.  Also, detention of highly
polluted initial runoff by the porous pavement, and dilution by less polluted
subsequent runoff might result in acceptable pollutant concentrations through-
out the storm duration.

     Natural vegetation and drainage patterns can be retained by the use of
porous pavements.  The clearing of trees from large areas for parking lots
is unnecessary, and their aesthetic benefits need not be lost.   Other
potential benefits include construction cost reductions due to elimination
of curbs and gutters, groundwater recharge, traffic safety resulting from
skid resistance and improved visibility on wet pavements.

Porous Pavement Development

     The earliest applications of porous pavements were for nonstorage
purposes and consisted of a thin layer of open-graded asphaltic mix placed
on top of a regular pavement to provide improved drainage and reduce the
possibility of skidding or hydroplaning.  Highways and airport runways
utilizing porous asphaltic pavements with no storage capacity have been
constructed in California, Kentucky, New Mexico and several other states.
The use of porous pavements as stormwater management systems was initiated
by the Franklin Institute in Philadelphia, Pennsylvania in 1971 under the
sponsorship of the Environmental Protection Agency (EPA).  The intent of
this study was to combine the porous asphalt mix with a porous base and
porous subbase in order to collect and store the runoff rather than to
remove it to a stormwater collection system.

     Existing porous pavements may be of two types:  open-graded asphalt
concrete overlying a crushed stone base course, such as is shown in Figure  1,
and lattice work concrete blocks shown in Figure 2.  Porous asphalt pavements
can be underlain by a gravel base course with whatever storage capacity is
desired.  The whole system can be isolated  from the natural ground by an
impermeable membrane such as a polyethylene liner, in which case some type

                                     699

-------
—i
o
o
POROUS  ASPHALT   COURSE
1/2"  TO 3/4" AGGREGATE
ASPHALTIC  MIX  (1.27 - 1.91 cm.)


FILTER  COURSE
1/2"  CRUSHED  STONE  (1.27cm)
2" THICK (5.08 cm)

RESERVOIR   COURSE
(2.54 - 5.08 cm)
l" TO 2" CRUSHED  STONE  VOIDS
VOLUME IS  DESIGNED FOR  RUNOFF
DETENTION

THICKNESS  IS  BASED  ON  STORAGE
REQUIRED AND  FROST  PENETRA-
TION


EXISTING  SOIL
MINIMAL COMPACTION TO  RETAIN
POROSITY AND PERMEABILITY
                            Figure 1.  Porous Asphalt Paving Typical  Section

-------
                         •LATTICE" TYPE PAVERS
 "ttRASSTONE"
BOIARD1 PRODS.
"QRASfiCRETE" (POURED IN PLACE)
      BY BOMANITE CORP.
   TURFBLOCK"
PAVER SYSTEMS, INC.
   WAUSAU TILE
                    "CASTELLATED" TYPE  PAVERS
           "MONOSLAB"
        GRASS PAVERS, LTD.
                         "CHECKER BLOCK"
                           HASTINGS CO.
                  FIGURE 2.  Concrete  Porous Pavements

-------
of an artificial drain would be needed. The result in these situations is
primarily attenuation of flow with very little flow reduction.  In the more
common situation the porous pavement system would be allowed to drain to
the natural soil at all points of contact.  The latter arrangement does not
preclude the use of artificial drains, which still might be needed in the
case of highly impervious natural soil.

     Lattice work concrete blocks will not be discussed at length here.
With grass planted in the interstices they can provide an aesthetic and
practical solution to water control problems. These also are underlain with
a porous base and can be underdrained.  Whether the grass will survive is a
function of the intensity of use of the area. Residential parking areas for
apartment complexes are normally vacant during the daytime, and, generally,
driving speeds are minimal.  Under these conditions, the grass suffers no
detrimental effects.   In heavier use areas the surface in the interstices
can be kept lower than the concrete surface so that the grass is kept trimmed
but not worn out by traffic passing over it.  The lowered level can create
a hazard to pedestrians by catching the heels of shoes.

State of the Art of Porous Asphalt Pavements

     Numerous porous asphalt pavements have been installed in Pennsylvania,
Delaware, Texas and in several other states.  However, for only a few of
the sites are any data available on design, hydrology, construction methods,
operation and maintenance of the site, and problems encountered in con-
struction and maintenance.  The only scientifically instrumented asphaltic
porous pavement area was part of an earlier EPA project at Woodlands, Texas (1)
Tables 1 and 2 includes general information on sites which have some technical
data available.  The pavements at most of these sites appear to have performed
adequately, but continuous monitoring to obtain and document definitive
information on their long term porosity and structual integrity has not
been carried out.

     An EPA project (2) designed to accumulate what data are available on
the design, construction, and operation of existing asphaltic porous pave-
ment sites concluded that:

     •   The design of porous pavements has to be undertaken with extreme
         care, particularly in areas where the natural soils do not have
         sufficient permeability to naturally drain the stored runoff within
         a reasonable time.

     •   The use of porous pavements is presently limited to parking lots
         only.  Ideally, these parking lots should be located on soils
         which have very low runoff potential or which have a high percola-
         tion rate.

     •   Infiltration and velocity reductions in porous pavements will
         result in some suspended particulate removal and some chemical
         pollutant reduction.  Preliminary data indicate that nutrients and
         concentrations of some heavy metals can also be reduced. In any
         case, the removal of water from the surface runoff regime prevents

                                     702

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            Table 1.   Existing Porous  Pavement Areas  (2)
Number                             Location
1A      South College Avenue Parking Lot.  Newark, Delaware
IB      Orchard Road Parking Lot.  Newark, Delaware
2       Marine Sciences Center.  Lewes, Delaware
3       Woodlands, Texas
4A      Bryn Mawr Hospital.  Bryn Mawr, Pennsylvania
4B      Bryn Mawr Hospital, Lot No. 2.  Bryn Mawr, Pennsylvania
5*      Havertown Hospital.  Havertown, Pennsylvania
5*      Newton, Savings Association Parking  Lot,  Washington
        Crossing, Pennsylvania
7       Travelodge.  Tampa, Florida
8*      Salisbury State College.  Salisbury, Maryland
9       Powell Ford Park.  New Castle  County,  Delaware
10*    Coney Island Housing Project.  North of Nathans,  New York
11*    Korman Interplex.  Philadelphia,  Pennsylvania
12      Bell Telephone Company, West Goshen  Township,
        Chester County, Pennsylvania
13      Bell Telephone Company.  Newtown, Pennsylvania
14      Hollywood Hospital.  Perth, Australia
15      Hamersley Headquarters Telecom.   Perth, Australia
        Zurich Hilton.  Zurich,  Switzerland
*Identifi*d existing sites  for which  data  were not available
                               703

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             Table 2.   Technical  Data  for  Existing  Porous  Pavement  Areas
town* Pa'
     Sits
 laudation    Design    Area      Slept
    Dace        Storm    (Acres)      X
	dr..)	
                                                             Soil
                                 Topojirmphy
                                    Permeability
                                      ft./Day
Side
Flow
Available
 Outflow
Tjpe pf UM
      1A


      IB
      AA



      4B

      7

      9





      12


      13



      14

      15
    1973


    1974





    1974




    1975




    1975




    1977

    1973

    1974






    1977



    1976




    1978
                                   6.0    0.64
                                           1.37
                                                     2.0
                                                                         0.50-1.00
                                                                          576.0
                                                  from
                                                  North
                  	     Brown
                          Clay,
                          Slightly
                          sandy.
                          Silt

        5.00       	     Clay         	
                          lenses,3
                          ft. In
                          diameter

—     0.50       	     Poor, re-    	
                          placed w/
                          3 ft. of
                          sand

5.0     0.75       1.4     	     1.00




        0.22       3.5     	    	



4.4     0.93       1.8     Clay,        0.050
                          •lit,        0.120
                          gravel,      0.003
                          alley
                          sands &
                          Sllty Clay

        2,76       2.1     Clenelg      	
                          Channery
                          Silt loan

7.2     4.00       	     Readlngton   	
                          Silt loan
          Southwest
          Comer

          Northweat
          and Southwest
          corners with
          french drains
                 LJght  Parking


                 Light  Parking
                                                                                                               Parking and  service
                                                                                                               Roads
                                                                                              Nearby Creek     Light Parking
runoff
froa
building
          3-4  Inch
          drains at
          subbase for
          each section
          Catch basin
          4  1-12"
          RCCF
Retalnage
trench along
N.W.  boundary
Roof      Outlet screen
drains    to Newton
onto      Creek
pavement
                 Parking  100 cars




                 Parking  33 cars

                 Parking  Lot

                 Parking  109 + cars
125 enployee cars,
100 company vehicles
                Parking and delivery
                        2.21
                                           Limestone
                                                                                                               Parking Lot

-------
                                                  Table 2.   (Continued)
o
en
Porous Psvsjsmt
SIM
1A



IB


2

3


AB





14

15"

Asphalt Mix »•••
Thickness Thlckau*
inches Inches
2.5 12



2.5 12


2.5 6

2.5 12


2.5 12

25 12



1.2 4-6
2.0
1.2 4-6
2.0
Drains Remarks/
Installed CossMBts
30 ft. trench, 15 ft. X Asphalt was laid on hot day,
3 ft. L-shaped 3/4 inch trouble with rolling, trouble
stone vlth trucks disturbing subbace.
had to regrade.
45 ft. trench, 15 ft. X Northwest Corner
3 ft. L-shaped 3/4 inch
stone
30 ft. trench, 15 ft. X Southwest Corner
3 ft. 3/4 inch stone
.„

cr«ek



from end of lot
trucks parking, water ponding
3 ft. in end of lot condition water runs off end of
lot
porous pavement lot. fork lift*
gouge pavenent
	 — 	 — 	 	 Llwestone base Is less expensive
than crushed rock



                             1 f«ot - 30.48 cm

                             I acre - 0.405 hectare

-------
the introduction of pollutants into the receiving water that could
create problems in downstream areas.

If it is known, or the possibility exists, that water infiltrating
in the ground could reach a water supply aquifer, adequate precautions
should be taken to determine that the surface runoff is not still
contaminated when it reaches the aquifer.  If there is a possibility
of adversely affecting the aquifer, the porous pavement areas
should be designed to be sealed off from the aquifer recharge
zone.

The aggregate in porous pavements should contain a minimum  of two
percent passing the Number 200 sieve to provide stabilization of
the coarse fraction.  Consequently, the following size gradation
is recommended for the open graded asphalt mix.

       Sieve                                 Percent
       Size                              Passing Through

     1/2 in.                                 100
     3/8 in.                               90-100
     #   4                                 35-50
     #   8                                 15-32
     #  16                                  2-15
     # 200                                  0-3

The total asphalt cement content for the mix is suggested to be
between 5.5 and 6.0 percent.  However, the actual percentage must
be determined in the field, particularly if the characteristics of
the aggregate are not known from previous experience.  Also, dry
aggregate should be used to avoid vapor release after the aggregate
is coated. Insulated covers must be used on all loads during hauling
to prevent the asphalt from crusting on the surface of the load.
Also, medium to light weight vibratory rollers are somewhat better
for compaction of the open graded asphalt mix.

A two-inch (5.08 cm) course of 0.5 in. (1.27 cm) gravel was found
to be desirable to stabilize the top of the gravel reservoir underlying
the open-graded asphalt mix.  This is referred to as the filter
course in Figure 1.  The gravel reservoir, composed of one to two
in. (2.54 to 5.08 cm) crushed stone, is designed to control the
total volume of runoff computed for the area based on a preselected
design storm and a hydrologic analysis of the area.  Both the filter
and reservoir gravels should be pre-washed to remove excessive fines
which may tend to affect the permeability of the underlying soil.
Because the length and width of the base reservoir are generally
limited by the dimensions of the parking lot, the only variable
dimension is the depth.  If sufficient depth cannot be obtained due to
physical limits, additional relief drainage structures such as french
drains and pipe drains may be installed.  If additional structures are
required, the cost of these structures can be quite expensive.

                             706

-------
         Consequently, conventional drainage schemes could become cost-com-
         petitive and viable alternatives.  If the subbase does not drain
         at a sufficient rate, relief drainage structures can be incorporated,
         or additional excavation, or replacement with material having more
         desirable drainage characteristics can be contemplated.

     •   The total thickness of the base reservoir should be the largest
         depth requirement for the bearing strength of the wet subbase, the
         hydrologic storage requirements, or the frost depth for the site.

     •   The initial costs of porous asphalt can be as high as 35 to 50
         percent above the cost of conventional paving.  However, the major
         reason for this difference is the required use of new technology
         involved in porous pavement production, primarily in gradation
         requirements and the narrow limit on asphalt cement content in the
         hot mix.   If curbs, gutters, or storm sewers are not required, the
         total cost of the parking lot can be comparable to or cheaper than
         a conventional parking lot, especially if the aggregate source for
         the asphalt mix as well as for the base reservoir are easily availa-
         ble.  It is anticipated that with the construction of additional
         porous pavement areas, technology transfer should be facilitated.
         Construction crews will become more familiar with the process, and
         contractors will be able to bid lower on porous pavement jobs.


     •    Existing porous parking lots were constructed without curbs
         and gutters around the surfaced area.  Porous pavements
         operate efficiently and there is less chance of debris accumu-
         lation on the parking lot if curbs are eliminated.


     •    For most efficient operation of porous pavements it is desirable
         that the subbase not be compacted or be only minimally compacted.
         This will retain the original permeability of the soil which can
         be substantially reduced after compaction.

     A recently completed EPA study of two asphaltic porous pavement parking
lot sites in Rochester, New York (3) was designed to demonstrate the structural
integrity and permeability of the pavements under severe environmental and
heavy truck traffic conditions.  Results of the study indicated:

     •    Peak runoff rates were reduced by as much as 83%.

     •    The pavement, which was subjected to 100 freeze/thaw cycles, showed
         no observable structural degradation.  In addition, the water
         drained through the pavement without problems during the winter.
         Through observations and flow monitoring,  the structural integrity
         of the porous pavement installed, where heavy load vehicles were
         parked, was not impaired.

     •    Clogging did result from runoff carrying a heavy sediment load.
         Clogging during the test study was relieved through cleaning.

                                     707

-------
     •   The cost of constructing a porous pavement parking lot utilizing
         an impermeable membrane and underdrains,  $18/yd^ ($22/m^),  is
         slightly higher than that of a conventionally paved lot with storm-
         water inlets and subsurface piping,  $16/yd2 ($19/m^).   If subsurface
         soil conditions are adequate to allow passage of the rainfall that
         infiltrates through the porous pavement,  and if there is no ground-
         water pollution problem, then the impermeable membrane and  under-
         drains are not needed and costs for both types of pavements would
         be the same.

Current Demonstration of Porous Pavements at Austin, Texas

     Although Table 1 indicates a number of porous pavement parking  lots
have been constructed, the design and construction of porous pavements is
in an early stage of development and only a few engineers and contractors
have any experience with this type of pavement.   This situation is likely
to continue until sufficient demonstration pavement areas are installed and
long term data is obtained on: (1) runoff quality and quantity changes; (2)
the effects of continuous saturation of the subgrade; (3) maintenance and
potential for plugging; and (4) the economics of using these pavements
under existing regulations.  An EPA project is currently underway with the
City of Austin, Texas to obtain some of this information on the following
seven types of parking lot surfaces:

     •   Porous asphalt
     •   Gravel
     •   Lattice concrete
     •   Conventional concrete
     •   Grass (natural condition for control)
     •   Conventional asphalt
     •   Conventional asphalt with trench storage

Characteristics to be investigated include: (1) construction feasibility
and design life; (2) runoff control; and (3) water quality control.   The
resulting information will be used to develop design criteria for porous
pavement construction.  Emphasis in this project is on the asphaltic type
of pavement.

     Each pavement is sloped to a collection barrel that is instrumented
with flow devices and recorders to measure both surface runoff and underflow.
The porous asphalt and gravel lots were constructed over an impervious
limestone area and all underflow moves horizontally and does not enter the
groundwater.  The lattice concrete and grass lots allow potential percolation
through the soil and into the groundwater.  However, the soil in the area
is clayey and slow to drain.  Test wells are included at these sites to
obtain samples of the water for quality analyses and  rain gauges are located
near each study area to accurately record rainfall intensity and duration.

     With regard to the porous asphalt there was a lack of experience by
the City of Austin paving department and the asphalt suppliers, in paving
                                     708

-------
with, and producing the required open-graded mix.   This lot is located on
the grounds of one of the City's maintenance facilities and serves as parking
space for the employees. The dimensions are 80 by 200 ft (24 by 61 m).
Figure 1 shows the type of pavement construction.   The thickness and particle
size of each illustrated course are given in Table 3.  AC-20 asphalt was
used in the porous pavement design and the characteristics of the mix are
shown in Table 4.  The depth was designed to store the 25 yr storm which is
4.2 in/24 hr (10.7 cm/24 hr).


 Table  3.   Thickness  and Particle  Size  of  Pavement  Courses  at  Austin,  Texas
Course
Porous Asphalt
Filter Course
Reservoir
Thickness
(in.)
1 3/4
2
8 to 42
Particle Size
See Table 4
3/4 in. Stone
1-2 in. Stone
             To convert in. to cm multiply by 2.54



          Table.  4   Characteristics  of Asphalt  Porous  Pavement  Mix



            Sieve Size	Percent Passing
1/2 in.
1/2 - 3/8 in.
3/8 in. - #4
#4 - #8
#8 - #16
#16 - #200
#200
Percent AC-20 Asphalt
Specific Gravity
Stability
100
7.6
59.3
21.1
3.4
8.2
0.4
5.5
2.221
645 psi









(4440 kN/m2)
     The mix was transported in covered trucks in order to maintain the
temperature near 300°F  (149°C) and was placed on the rock base using standard
paving equipment.  Since the degree of compaction is critical in obtaining
a structurally sound, but highly permeable pavement, much discussion took
place at the site between the pavement designer and the foreman of the
paving construction crew.  Pneumatic and two different size  flat rollers, 2
                                     709

-------
and 8 ton (1820 and 7280 kg), were available for use.  It was concluded after
several trial and error compaction techniques that 2 passes with the 2 ton
flat roller and 3 with the pneumatic roller would produce an optimum compromise
of strength and permeability.  Since there exists a trade-off between struc-
tural integrity and inherent permeability as a result of the degree of compac-
tion employed, it was decided to vary the compaction in several sections of
the parking lot and evaluate future performance of the porous pavement in
order to correlate the results with construction techniques.

     The permeability characteristics of the porous asphalt surface were deter-
mined after 18 months of vehical use by in situ tests using an infiltrometer
designed and fabricated specifically for this study.  The infiltroiuater con-
sists of a 6-inch (15.2-cm) inside diameter clear PVC pipe 18 inches (45.7 cm)
high with a stopper mechanism which allows a timed release of a known volume
of water through a 3.5 inch (8.9 cm) diameter hole at the base of the infil-
trometer.  The permeabilities of the porous asphalt surface ranged from 152 in/
hr (386 cm/hr) to 5290 in/hr (13,437 cm/hr) with an average rate of 1766 in/hr
(4486 cm/hr).  This rate compares to an average rate of 70,000 in/hr (177,800
cra/hr) for the 2-inch (5 cm) reservoir base course.  Notable exceptions to
this average rate occurred on the west side of the lot, throughout the driveway
path, and in the northeast corner.  Lower than average infiltration rates on
the west side of the lot can be attributed to rolling the asphalt at a tempera-
ture higher than 180 F (82.2 C).  The driveway path has more traffic than other
parts of the lot and may be compacted more than normal.  The northeast corner
of the lot was noted to have soil accumulating in the pores of the porous
asphalt surface, possibly transported there by tires of vehicles.

     Table 5 compares the Austin permeability results with others reported in
the literature.  There is a wide variation in the results which is probably
related to use of different types of permeability testing techniques rather
than to the use of different compaction methods.  The Austin results were
measured with a very low hydraulic head most closely simulating actual condi-
tions.  In all cases very high degrees of porosity were initially obtained
with asphaltic porous pavement.

          Table 5.  Asphalt Porous Pavement Permeability Test Results
           Project Location                 Porosity  (in./hr)
                                            Average     Range
           Austin, Texas                     1766       152 -  5290
           Woodlands, Texas(D               2000
           Rochester, New York<3)              -        170 -  1980
               To convert in./hr to cm/hr multiply by  2.54
                                      710

-------
     The data from the Austin, Texas project combined with what information
can be obtained from asphaltic porous pavements constructed in the early
1970's will be used to develop a design methodology for porous paving systems
which can be used by planners, engineers, and building plan reviewers.

Conclusions

     Porous pavements of various types constitute a methodology for signifi-
cantly reducing runoff from parking lots and lightly traveled roads or for
accomplishing flow storage and attenuation.  Costs can be competitive with
conventional pavement if curbs, gutters and storm sewers can be eliminated.
Installation of collection drain piping within the base material to move the
underflow laterally to an appropriate discharge point is necessary in locations
underlain by impervious soils.  Information is available to construct these
pavements and more is presently being obtained, but it has not yet been satis-
factorily organized and has not reached a large segment of pavement designers
and constructors.  More data on groundwater pollution potential would be use-
ful.  The most significant lack of informaiton concerns pavement life and long
term maintenance.  Although some installations have been in existence for
about a decade, their recent porosity has not been measured and the cost of
maintenance has not been adequately documented.
                                      711

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INSITUFORM CONTROL OF INFILTRATION

Introduction

     The infiltration of groundwater into sanitary sewers through leaky joints,
and cracks and breaks in sewer pipes can add significantly to the amount of
flow to sewage treatment plants.  This is especially true during wet weather
when the groundwater level is elevated.  Also, during wet weather there can be
inflow of water from roof leaders and other types of drains.  The result of the
combination of infiltration and inflow (I/I) is the overloading of treatment
plants with a reduction in operating effectiveness.

     Since the passage of the 1972 Clean Water Act Amendments, there has been
a determined effort in the United States to reduce the effects of I/I at sew-
age treatment plants.  There has been greatly increased activity in the use
of sewer rehabilitation techniques.  A survey conducted by the EPA in 1980 (4)
indicated, however, that these techniques were not nearly as effective in
reducing I/I as estimated by engineers before the rehabilitation was carried
out.

     There are a number of possible reasons that have been proposed for the
ineffectiveness of sewer rehabilitation methods.  One significant reason
appears to be the lack of completeness in sealing all potential leaks.  The
sealing of only those leaks which appear to be the largest in volume
apparently results in an increase in water level outside the sewer line and
the initiation of new leaks at unsealed locations that formerly did not leak.
A rehabilitation technique of reasonable cost that could seal all unwanted
openings in the pipe wall should decrease measurably the amount of infiltra-
tion.  A method conceived in England over a decade ago, but only recently
introduced to the United States, has a good potential for completely sealing
all leaks.  It involves the complete lining of the inside of the pipe with a
thin plastic layer and has the commercial name "Insituform".  The plastic
layer has sufficient strength to cover openings into a sewer such as service
laterals and to prevent their further discharge.  The method has, therefore,
the capability of eliminating inflow from illegal connections.  The method
also produces little surface disturbance since installation can be made in
most cases through existing manholes.

     To assess the effectiveness of Insituform, two full-scale evaluations
were undertaken, one at the Village of Northbrook, Illinois under a coopera-
tive agreement between the Village and EPA.  The information presented here is
largely from that project (5).  The other evaluation is being conducted in
                                      712

-------
Hagerstown, Maryland.   No information is yet available from the Hagerstown
project.

Description of the Lining Procedure

     The concept of the Insituform process is to form a long tube or bag of
partially polymerized thermosetting resin impregnated on a felt backing and
closed at one end, and to invert this tube into the pipe to be lined, by
filling with cold water.  The felt tube has a thin film of polyurethane on
what is initially the outside.  Upon inversion of the tube into the pipe,
the polyurethane film forms the pipe surface which is very smooth.  This
film also provides a leak proof barrier to the water being used for inversion.
After inversion, hot water is pumped into the tube to cure the liner by
completing polymerization.  Figure 3 shows the important steps in installation
of the liner.  After installation the end of the tube is cut off with a
power saw and the wall of the manhole near the pipe is finished with a
sand-resin mixture.  Reconnection of service laterals is carried out with a
rotary cutter.  For pipes too small to enter, a television camera-cutter
combination has been developed.

     Because this lining procedure is very new and improvements continue to
be made, it is difficult to place precise limitations on the range of pipe
diameters for which Insituform is practical.  About 36 in. (91 cm) diameter
is presently the largest size that can be lined with the water inversion
method.  Variations have been utilized for larger pipes in Europe including
air inversion.  Manhole covers in the United States can accommodate equipment
for lining pipes up to about 24 in. (61 cm).  Larger pipes would require
more complicated preparation and, therefore, higher cost. The present minimum
size is six in. (15 cm).  Smaller sizes present problems during inversion
and do not accommodate the available TV-cutter equipment.

     Specialized equipment and specific procedures have been developed  for
installation that allow for rapid completion of the lining of a pipe section.
The felt bags or tubes can be prefabricated away from the site to fit the
pipes involved.  Impregnation can be conducted on-site or off with shipping
in a refrigerated truck.  Impregnation is not a lengthy procedure if done
at the site.  The water pressure for inversion is provided very simply  by
maintaining a sufficiently high column of water in an inversion tube.   The
flattened liner is led into the top of the  inversion tube and the open  end
of the liner is firmly attached to a shoe at the tube base which has an
appropriately sized round opening.  The pressure from the water in the
inversion tube  inverts the liner similarly  to the blowing up of a balloon.
A rope  is attached to the closed end of the liner that is used to control
the rate of inversion.  Too rapid an inversion can result in momentary  head
loss and poor contact of  the  liner with the pipe.  A hose is also attached
to the end of the liner to be used after  inversion is complete to supply
hot water at the  far end  of the liner  segment for curing. A  boiler  and
pump are used to produce  and circulate the hot water.

     At Northbrook, two consecutive 12 in.  (31 cm) diameter vitrified clay
pipe segments were lined.  Segment lengths were 150 ft (46 m) and 432 ft


                                     713

-------
1.  Lining material 1s threaded
    Into Inversion tube and
    attached  at bottom
                                       2.  Lining material being in-
                                           verted after inversion
                                           tube is  placed against pipe
                                           opening
Inversion
tube
Lining
material
                                                                      /-
                                                                     /  t
 Block
to hold
inversion
tube in
place
Pipe to be  lined
                       Manhole
3. Lining  material nearly inverted


Hose for hot water
                                       4.  Completed  lining ready for
                                            cutting of end of tube
             Figure  3.   Steps  in  Lining  with Insituform
                                       714

-------
(132 m).   There were manholes at the entrance to the first segment, between
the two segments and at the outlet of the second segment.  There were two
six in. (15 cm) service laterals entering the first pipe segment.  The
sewer was a sanitary sewer installed in 1962 and had many offsets, and
radial and longitudinal cracks.  Some sections were deteriorated to the
point of not being circular.

     Before lining, the sewer segments were cleaned well since any remaining
debris would not be forced out during inversion, but would increase roughness
of the lining, reduce flow capacity and reduce strength.  Very sharp pro-
trusions could break the liner and interfere with curing.

     The felt tube was built up from two, 3 mm layers of densely needled
polyester fiber.  Thickness can be increased by adding 3 mm layers.  Impreg-
nation was conducted at the site by filling the liners with the appropriate
amounts of a catalyzed thermosetting isophthalic-acid-based resin and passing
the liner through a system of conveyers and rollers to thoroughly wet all
of the felt.  Inversion was carried out using a 6 m static head.  The two
pipe segments could have been lined with one length of liner and one inversion,
but two were used on successive days to allow observation by a larger number
of interested observers.

     The desired curing temperature for the chosen resin was approximately
180°F (82°C).  The curing cycles for the two segments are shown in Table 6.
Considerable time was required to heat the water to curing temperature.
Cooling is purposely slowed to an hour or more to prevent rapid contraction
that might cause separation of the liner from the pipe.  Small thermocouples
placed between the inside of the original pipe wall and the outside of
the liner at both ends of each length being lined were used to determine
whether curing temperature was being reached through the total thickness
of the liner.  The conditions shown in Table 6 would be typical of most
installations.

Results at Northbrook

     The success of the lining process was tested by observing the infil-
tration into the upstream pipe segment just before and just after lining
and by observing exfiltration from the downstream segment just before and
just after lining.  The infiltration test was carried out by plugging the
upstream manhole and measuring flow over a weir at the downstream end of
the pipe segment.  Groundwater levels were approximately 35 cm above the
crown at the outlet.   The average value of infiltration before lining was
19,500 gpd (74 up/day) and after lining was about 100 gpd (0.4 m^/day).
The small amount of inflow after lining is believed to have resulted from
leakage at the upstream manhole since television (TV) inspection of the
pipe showed no breaks in the lining.  The exfiltration test was carried
out by plugging the line just above the manhole at the upstream end of
the pipe and the line just below the downstream manhole.  The pipe segment
was then flooded to 3 ft (91 cm) above the crown at the upper manhole.
The rate of fall of the water was measured.  Before lining, the rate of
exfiltration was 3,800 gpd (14 nrVday) and after lining 270 gpd (1.0 m-Vday).


                                     715

-------
The small amount of exfiltration after lining is believed to have occurred
in the manholes.

     An indirect measure of the effectiveness of lining was an obvious
increase in the leakage into the adjacent manholes through cracks in the
manhole walls.  This observation confirms the experience with sewer grouting
methods where, after grouting, leakage appears at points that did not
formerly leak.  The cause is ascribed to higher groundwater level resulting
from the elimination of the most significant leaks.   Where the condition
of manholes is questionable, their rehabilitation should also be considered.
                      Table. 6  Resin Curing Cycles
                                   Temperature Range
Upper pipe segment
 55-160,  13-71
160-185,  71-85
    185,  85
185-100,  85-38
Curing Time
    (hr)

   0.75
   0.5
   2
   1
Lower pipe segment
 55-160, 13-71
160-185, 71-85
    185, 85
185-100, 85-38
                                                          4.25 Total
   1.25
   0.75
   2
   1.5
                                                          5.5 Total
     One of the advantages claimed for the insitu lining of sewers is the
increased smoothness that, in relation to carrying capacity, compensates
for, or more than compensates for, the slight decrease in pipe diameter.
At Northbrook the Manning coefficient was measured after lining.  In the
upstream segment the value was 0.0078; in the downstream segment the
value was 0.0085. These values are comparable with those for other plastic
pipe such as PVC. Accurate values for the Manning coefficient were not
obtainable before lining so a comparison of maximum water carrying capacities
before and after lining was not possible at Northbrook.

     A number of physical properties of samples of the lining material
used at Northbrook were measured.  These are shown compared to PVC in
Table 7.
                                     716

-------
           Table 7.  Properties of Insituform Compared to PVC
Property
Tensile Strength (psi)*
Modulus of Elasticity (psi)
Flexural Stength (psi)
Compressive Strength (psi)
Coefficient of Thermal
Expansion (cm/cm °C)
Insituform
5,420
475,000
9,320
15,500
5.96 x 10~5
PVC
7,200
400,000
11,000
9,000
5.2 x 10-5
     * To convert psi to kN/m^ multiply by 6.895

     It can be concluded from this comparison that the two materials are
very similar in their physical characteristics.

Insituform Costs

     Approximate costs for long total length installations of Insituform
are shown in Table 8.  These figures include the fabrication and installation
of the liner and cutting of openings to service laterals.  Additions for
pipe cleaning and inspection and for bypass pumping of sewage must be
made as shown at the bottom of Table 8.  In addition, there are other
relatively small costs for setting up of equipment (mobilization) and for
traffic control.


                        Table 8.  Insituform Costs
Sewer Diameter
(in.)*
6

12

18

24

Liner Thickness
(mm)
3
6
6
12
6
12
9
15
Cost Per
Lineal Foot
($)
33
39
47
55
57
66
74
86
Cost Per
Meter
($)
108
128
154
180
187
217
243
282
          Note: Add $1,900 per line for bypass pumping.  Add $1.90  for
          6 in. to 15 in. pipe and $2.50 for 15 in. to 30 in. pipe  per
          foot for preliminary cleaning and inspection.

          * To convert in. to cm multiply by 2.54
                                     717

-------
     A realistic experienced cost cannot be obtained directly from the
installation at Northbrook because of the demonstrative nature of the
project which limited the total length to be lined and increased installation
time and cost for sewage bypass.   An estimate can be made for Northbrook,
however, based on Table 8 information.  For the two pipe segments lined
and with $1,500 estimated for mobilization and traffic control,  the cost
would be approximately $55/ft ($166/m).

     In making this estimate it is assumed that other sewers in the area
would be lined at the same time to take  advantage of the large-order
prices shown in Table 8.  An estimate was also made at Northbrook for the
cost of complete replacement of the pipes as an alternate to lining.
This cost was $79/ft ($260/m).  At Northbrook, therefore, the cost of
insitu lining was about 70% of the cost  of replacement.  It is important
to remember, however, that sewer replacement usually causes severe disturbance
to or prohibits traffic entirely on the  streets involved, and often causes
significant financial loss to businesses in the area or inconvenience to
residents.   Because insitu lining requires little or no surface disruption,
the inconvenience is minor and of only a day or two duration.

     The Washington Suburban Sanitary Commission (WSSC) became interested
in Insituform and has made cost estimates for both Insituform lining and
sewer replacement for a number of sewers being considered for rehabilitation
in Maryland (6).  These estimates are shown in Table 9.  At these locations
the ratio of the cost of Insituform to the cost of replacement ranged
from 36% to 76%.  For the sum of the costs for the sewer pipe segments,
the ratio was 44%, significantly lower than at Northbrook.  This probably
reflects the greater congestion of some of the Maryland sites, requiring
higher cost for sewer replacement.  The costs indicate, as in Northbrook,
that insitu lining has potential for reducing significantly the cost for
rehabilitation of badly deteriorated sewers.

 Table 9.  Comparative Costs of Insituform and Sewer Replacement at WSSC
Pipe
Diameter
In.)*
6
8
10
12
15
18
24
TOTAL
Length
(ft)**
556
10,304
10,445
4,015
1,667
782
3,272
31,041
Insituform Cost
$ 27,495.00
482,269.26
492,999.34
225,312.35
103,173.40
68,240.80
336,847.60
$1,736,337.75
Sewer
Replacement Cost
$ 56,000.00
1,028,000.00
1,365,000.00
422,000.00
184,000.00
90,000.00
800,000.00
$3,945,000.00
         To convert in. to cm multiply by 2.54
         To convert ft to m multiply by 0.305

                                     718

-------
     At Northbrook the condition of the pipes was too poor to consider
specific point repair and grouting.  The same was true for the pipe seg-
ments considered by the WSSC and shown in Table 9.  Had grouting been
practical, it would have been a cheaper alternative.  Grouting is not as
effective as Insitufortn and in a number of documented cases was  essentially
ineffective (4).  The cost effectiveness of grouting in terms of actual
reduction in I/I can, therefore, be very low.

Conclusions

     Insitu lining of badly deteriorated sewer pipes provides a new rehabil-
itation alternative that reduces infiltration essentially to zero. The
cost is substantially less than for sewer replacement and the surface
disturbance is greatly reduced.  The cost associated with surface disturbance
can be very significant, especiallly in the centers of cities and other densely
populated areas.  The procedure is more expensive than grouting and therefore,
would probably not be the method of choice where deterioration was minor and
where grouting would be judged adequate.  Care must be taken, however, in
estimating the effectiveness of grouting.  A survey of past grouting results
indicates that the effectiveness, and resulting cost effectiveness, is likely
to be greatly overestimated.

     Because insitu lining is less than ten years old and experience in the
United States is of very short duration, there are no dependable data on lining
life or long term maintenance requirements.  Continuing observation of Insitu-
form installations is necessary to determine conclusively the technical and
economic feasibility of this sewer rehabilitation method.
                                     719

-------
                               REFERENCES
1.   Characklis, W.G.,  et al., "Maximum Utilization of Water Resources in
     a Planned Community - Executive Summary," EPA-600/2-79-050a,  U.S.
     Environmental Protection Agency, Cincinnati,  Ohio, July 1979.

2.   Diniz, E.V., "Porous Pavement:  Phase 1,  Design and Operational Criteria,"
     EPA-600/2-80-135,  U.S.  Environmental Protection Agency, Cincinnati,
     Ohio, August 1980.

3.   Murphy, Jr., C.B., et al, "Best Management Practices Implementation
     Rochester, New York," Great Lakes National Program Office,  U.S.
     Environmental Protection Agency, Chicago, Illinois  60604.

4.   Conklin, G.F., and Lewis, P.W., "Evaluation of Infiltration/Inflow
     Program," Report for the Municipal Construction Division,  U.S. Environmental
     Protection Agency, July 1980.

5.   Driver, F.T., and  Olson, M.R.,  "Demonstration of Sewer Relining by
     the Insituform Process, Northbrook, Illinois," U.S.  Environmental
     Protection Agency, Draft Report, July 1981.

6.   Thomasson, R.O., "Repair Replace Reconstruct  All in One,"  Washington
     Suburban Sanitary  Commission,  Hyattsville, Maryland.
                                     720

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SEQUENCING BATCH REACTORS FOR MUNICIPAL WASTEWATER TREATMENT
                      Edwin F.  Barth
               Wastewater Research Division
       Municipal Environmental  Research Laboratory
          U.S. Environmental Protection Agency
                   Cincinnati,  Ohio 45268
     This paper has been reviewed in accordance with
     the U.S. Environmental  Protection Agency's peer
     and administrative review policies and approved
     for presentation and publication.
                  Prepared for Presentation at:
               8th United States/Japan Conference
                             on
                  Sewage Treatment Technology


                        October 1981
                      Cincinnati, Ohio
                             721

-------
SEQUENCING BATCH REACTORS FOR MUNICIPAL WASTEWATER TREATMENT

Edwin F. Earth
Wastewater Research Division
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio  45268
INTRODUCTION

     Antiquated techniques and modern hardware technology can be combined to
provide an alternative process for municipal wastewater treatment.

     At the present time, when continuous flow activated sludge is consid-
ered the paradigm of secondary treatment, it may seem contemptible to suggest
a batch process may have superior attributes.

     Historical technology is replete with examples of batch treatment of
municipal wastewater.  Sidwick and Murray (1) have outlined the evolution of
batch processes into continuous flow processes in England.  Early, in land
treatment practices, it was recognized that intermittent irrigation of waste-
water was necessary for reaeration of the soil to occur.  In the year 1897,
ways to conserve land were investigated.  Vessels were constructed which
contained various fine media (3 mm) to try to duplicate soil surfaces.  The
first of these were operated as simple fill and draw in accordance with
intermittent land application experience.  Later, a cyclic process was insti-
tuted which consisted of 2-hour fill, 1-hour stand full and 5-hour drain.
The cycle was repeated twice daily.  Seventy-eight percent removal of organic
matter was reported.  The need to supply oxygen in the proper amount for
active biological oxidation was the key finding of this early work.  From
this point on, two divergent developments led to continuous flow processes.
One utilized larger media with greater void space so that wastewater splash-
ing from surface to surface entrained oxygen from the surrounding air.  This.
of course, is the now familiar biological trickling filter.  The other
retained the concept of a flooded vessel containing media, but instituted
continuous flow with suitable valving and supplied air by an external blower.
This technology was the progenitor of the Hays Process (2) and Imhoff's
contact aerators (3).  Conceptually, Imhoff discussed a variation of contact
aerators which described rotating biological contactors before their actual
invention.

     The precursor to the various, now familiar, continuous flow activated
sludge processes was actually a fill and draw system operated as a batch
process.  Ardern and Lockett (4) in 1914 were among the first to show the
benefit of retaining substrate adapted organisms for efficient treatment.
Working with 2.3 liter flasks containing Manchester, England raw wastewater,
they showed  that the batch aeration period to achieve nitrification could
be reduced from 5 weeks to 9 hours if the sludge that accumulated from each
                                     722

-------
batch were retained in the flask after decanting the nitrified liquid.  They
coined the term "activated sludge" to describe the resultant biological
mass.

     In later studies, these same investigators (5) showed good nitrification
in 4 hours and suggested a full-scale operational cycle as shown in Table 1.

     Alvord (6) described some of the automatic dosing siphons and mechanical
devices used to switch flows in early batch systems.  Figure 1 is a view of
the 10 bay, 900 m^/d (0.25 mgd) intermittent batch sand filter constructed
on the shore of Lake Michigan in 1901 for the Village of Lake Forest, Illinois,

  Table 1.  Batch Treatment of Manchester Wastewater  (modified from  Ref. 5)
Analytical
Raw
kMnOij (Oxygen 124
Absorption)
NHij-N 37
Organic-N 12

N02-N
N03-N
Results, mg/1
Effluent
18
18
1.9

1.1
14
Operational Cycle , hours
Filling, 1
Aeration, 4
Settlement, 2
Discharge, 1
__
3 cycles per day
20 percent activated
Sludge by volume
 The building on the hillside housed the control mechanism for intermittent
 gravity application.  Figure 2 is an inside view of the building showing
 the flow switching mechanism on the floor above the dosing chamber (7).
 When influent flow increased the liquid level in the dosing chamber, it
 caused the iron ball,  resting on a plate attached to a float mounted pole,
 to elevate to the top level of one of the 10 inclined planes.  The ball
 then rolled down the plane and activated a counter weighted valve operator
 leading to one of 10 discharge pipes to the intermittent sand filter.  The
 ball rested on the valve operator until the discharge lowered the level of
 the dosing chamber, causing the next float position to lower to accept the
 ball,  and thereby release the valve operator.  There was no discharge until
 the influent flow again increased the liquid level in the dosing chamber
 and caused the ball to rise to the next incline.  The only design constraint
 was to insure that the dosing chamber discharge rate exceeded the influent
 rate.   There was no need for external energy or operator, and the continuous-
 ly circulating ball unerringly dosed each bay in sequence.
                                     723

-------

                           ,  ..

                        *   '• *      -    *   *'
ro
-p.



                                Figure 1.  Village of Lake  Forest's Intermittent

                                             Sand Filters, Year 1901

-------
no
01
                                   Figure 2.  Control  Device  for Intermittent

                                                 Sand Filters, Year 1901

-------
    Fill and draw or batch systems were never applied to any great  extent
for municipal treatment.  By 1920, when larger facilities were being con-
structed, batch systems were no longer considered viable.  Batch systems,
at that time period, would have required a high degree of manual operator
attention, and reliable process valving, timing and switching technology
was not available to counter that deficiency.

     Lack of implementation of batch treatment is not due to early opera-
tional or process failures, in reality batch treatment for mainstream appli-
cation is a long forgotten successful technology.  Developments of new
hardware devices, since the year 1900, such as motorized valves, pneumati-
cally actuated valves, electronic and mechanical timers, solenoids, level
sensors, and flow meters, coupled with an omnipotent microprocessor or
process controller can revitalize this technology.

PRESENT DAY BATCH PROCESSES

    Many present day industrial processes are batch processes, such as
dairy, steel, pharmaceutical and antibiotic, fine chemical, cosmetic, and
paint.

    In some instances, state regulatory agencies require toxic wastes, such
as cyanide, be detoxified by batch operation to insure the effluent can be
monitored before discharge.

    Most modern municipal treatment facilities utilize batch treatment in
one guise or another, such as anaerobic digestion, aerobic digestion or
intermittent discharge lagoons.  Tchobanoglous  (8) calls attention to the
fact that the classical biological oxygen demand test (BOD) is a batch
process.

    Renewed interest in main stream batch treatment resulted from a mentorial
article by Pasveer (9)-  He reported on the conversion of a continuously
operated oxidation ditch, treating the waste from Sancta Maria Hospital,
Noordwijkerhout, Holland, into a discontinuous discharge process with inter-
mittent aeration.  The operational change resulted in the control of a
filamentous activated sludge, improved clarification and yielded 90 percent
denitrification.

   Goronszy (10) has applied this concept of single tank treatment systems
in Australia.  Extended aeration processes are operated with continuous
inflow but discontinuous discharge.  The liquid level in the tank varies
and various type decant devices are used.  Aeration is provided in a cyclic
manner to encourage nitrification and denitrification.

   These two approaches provide a high degree of treatment due to the fact
that they are both lightly loaded systems.  Since the volume of the tank is
large in comparison to the influent flow, the possibility of short circuiting
influent to effluent  is minor.
                                     726

-------
   Irvine, the doyen of current investigations of batch process, has suggest-
ed a uniform terminology and united the batch concept with modern control
strategies (11).

BATCH TREATMENT CONCEPTS

Batch Compared With Continuous Flow

   Most simply stated, the conceptual difference between batch and continuous
flow is that continuous flow processes have spacially related unit operations,
whereas unit operations are timed sequentially in batch processes.

   The generic batch process can have several modifications, such as single
reactor, multiple reactors in series or parallel, and sequencing reactors,
all with variable liquid levels.  The most simple of these would be a variable
volume single reactor as depicted in Figure 3, which would be suitable  for
a rural or small industrial situation where no flow occurs for part of  the
day.  The figure shows the different time dependent modes that would occur
in a complete cycle of a 1-tank reactor.  The modes are labeled according
to Irvine's (11) recommendation.  The percent of maximum volume and cycle
time are only illustrative.  For any batch system, Fill and Draw must occur
in each cycle, but React, Settle and Idle could be eliminated depending on
the objective of the treatment.  Alternatively, other modes could be inserted
by varying time and operational controls within a cycle.  Systems of this
nature have a great deal of flexibility.  Table 2 compares batch and continu-
ous flow processes.  In several instances drastic differences can be noted
and their impact on design, operation and effluent quality are apparent.

   Since the discharge is periodic,  the possibility exists, within constraints,
to hold effluent until some predetermined specific residual is obtained.

   The cyclic organic and hydraulic  loading coupled with inherent equaliza-
tion allow control to be exerted over substrate tension in the reactor  by
suitably matching oxygen supply.

   No recycle* pumping is required since the mixed liquor is always in the
reactor, thereby saving on energy.  All the active microbial mass is avail-
able and not shunted through an inactive period in a clarifier.

   Liquid solids separation occurs under near ideal quiescent conditions.
During the settling period there is no hydraulic motion due to inflow,
outflow or recycle, as in continuous flow systems.  The effluent exit piping
must be sized larger than influent piping because flow accumulated over a
long time span is discharged in a much shorter time span.

Sequencing Batch Reactors

   In situations where the influent  flow is continuous,  two or more tanks
operated in sequence would be needed to treat the flow.  A two-tank sequenc-
ing batch reactor (SBR) schematic is shown in Figure U.  As one tank progress-
es from the FILL to the REACT mode,  flow is switched to the second tank,

                                     727

-------
               SINGLE TANK SBR
PERCENT OF:
MAX  \ CYCLE ,NFLUENT
      _\ tftmmm  inrtUCW I
VOLUMETIME
  25    20
                           PURPOSE/OPERATION
•M ^^ "^
FILL
^W&V^&M'^'hc
to-j?ijcv.o..T:o A'^-^O n'J -••••'OJ-

ADD
SUBSTRATE
AIR
ON/OFF

 1OO
3O
                  -  REACT  w-i

                                               AIR
                                             ON/CYCLE
                                     REACTION
                                       TIME
 1OO   3O
                      SETTLE
                                     CLARIFY
                                                AIR
                                                OFF
  35     15
              DRAW
                  EFFLUENT
                                     REMOVE
                                     EFFLUENT
                                                AIR
                                                OFF
  25
               IDLE
                                      WASTE
                                      SLUDGE
                                                AIR
                                              ON/OFF
             Figure 3.  Single Tank Batch Reactor
                           728

-------
       PLAN VIEW OF SBR
TANK #1
                                 TANK #2
  EFFLUENT
^ —
VALVE 1
CONTROLS |
PROCESSj SENS
SENSORS ,
A ' '
PROCESS 	 ^_
CONTROLLER
IF —
PUMP
VALVE (EACH
CONTROLS JET)
""" °~~ L
1 3
I-K o o o>-
1
EL
DRSA
AND
CONTRO
A
V
-vx
o
FLOATING
WEIRS ~~
DIRECTIONAL
JET
AERATORS
	 j*q
7
»•< O O O^
A
A
<3
1 	 ^ ^
INFLUENT ^ |

PRIMARY
TANK
	 >
•^M
^
, AERATION
TANKS
- 4
ALTERNATING CYCLES ^
en i AKin rtDA\A/
V
y

" 6 AIR
COMPRESSOR
r (TO EACH
l JET)
Figure 4.  Sequencing Batch Reactors
                729

-------
           Table 2.  Comparison of Batch and Continuous Processes
  Parameter
   Batch
   Continuous
Concept

Inflow

Discharge

Organic Load

Hydraulic Load

Aeration

Mixed Liquor


Clarification

Flow Pattern


Equalization

Flexibility

Hydraulic Sizing
Time Sequence

Periodic

Periodic

Cyclic

Cyclic

Intermittent

Always in
 Reactor, no Recycle

Quiescent Hydraulics

Perfect Plug


Inherent

Considerable

Variable
Spacial Sequence

Continuous

Continuous

Even (by convention)

Even (by convention)

Continuous

Recycles through
 Reactor and Clarifier

Hydraulic Motion

Complete Mix or
 Approaching Plug

None

Limited

Uniform
which starts a new cycle in the FILL mode.  When capital costs  and  operational
controls are considered, Irvine and Richter (12) indicate a  three-tank
system is near optimum for flows above 3,785 m^d (1 mgd).

Control of Substrate Tension

   SBR's are dynamic processes and a great deal of selective control can  be
implemented.  Figure 5 shows the time profile of soluble organic  carbon,  in
an idealized reactor, with three different schemes for  aeration during  the
FILL mode.  A great deal of control over  the substrate  tension  that the
activated sludge is exposed to is possible.  Ketchum  (13) has discussed
this attribute in relation to bulking sludge.   High substrate tension
during part of a cycle places filamentous organisms at  a competitive disad-
vantage compared with floe forming organisms.   Apparently, filamentous
organisms cannot store substrate during anoxic  periods  but floe forming
organisms can; therefore, at commencement of aeration,  these latter organisms
have a growth advantage.  Goronszy (14) has shown a direct correlation
between anoxic and aerobic periods with sludge  volume index  (SVI) for
domestic wastewater.  Increase in aeration time produced higher SVI's.
                                     730

-------
                                    SUBSTRATE TENSION IN SBR
—i
to
                                            345


                                            HOURS INTO CYCLE
                             Figure 5.  Time Profile of Soluble Organic Carbon

-------
   Figure 5 also illustrates other facets of SBR technology.  With continuous
air supply during both FILL and REACT, the soluble substrate is always at a
low concentration, very similar to a complete mixed activated sludge process.
With no air supply during FILL and air during REACT, the process conditions
resemble plug flow.  Air supplied in a cyclic fashion is intermediate between
these two process regimes.  If the influent waste contained appreciable
nitrates, the anoxic FILL could be used to force denitrification and conse-
quently reduce aeration requirements.  If a waste required some degree of
anaerobic conversion before aerobic biodegradation could occur, provision
could be made for this by selection of the most suitable aeration scheme
during FILL.

Mixed Liquor and Oxygenation Requirements

   The concentration of activated sludge mixed liquor also changes in a
dynamic fashion as shown in Figure 6.  Since the mixed liquor never leaves
the reactor, its concentration varies with the mode of the cycle.  During
FILL the initial concentration becomes diluted by the incoming waste volume,
a slight increase due to synthesis would be noted during REACT, pronounced
thickening occurs during SETTLE with slight densification during IDLE.
Sludge wasting could occur during any mode but IDLE would usually be the
most appropriate.  Other modes and aeration schemes could change the general-
ized pattern shown in Figure 6.  For instance, prolonged aeration during
FILL, REACT or IDLE could show an influence from endogenous respiration
(15).

   Aeration requirements also change with time in an SBR reactor.  Figure 7
shows oxygen uptake rates in the reactor liquid and specific oxygen uptake
rates of the activated sludge during FILL and REACT modes with municipal
strength wastewater.  Initially from a concentration standpoint, there is a
high oxygen demand due to the high mixed liquor solids content, as noted in
Figure 6.  Reduction of this concentration demand is a function of dilution
by incoming flow, substrate concentration and the oxidative activity of the
activated sludge.  A stable demand is reached near the end of the REACT
mode.  The specific oxygen uptake varies from an endogenous level at the
end of REACT to a moderate metabolic rate near the end of FILL.  Other
aeration schemes or mode sequences would alter the shape of these curves.

Flexibility of Modes Within a Cycle

   The flexibility of the SBR concept can be noted by considering alternative
modes within a cycle for the purpose of denitrification, as shown in Figure
8.  A jet pump, which can serve as an aerator or mixer, or  both, is installed
in the reactor.  The figure shows how the different modes would be controlled
to achieve the sequence of events necessary to accomplish carbonaceous
removal, nitrification, denitrification and liquid-solids separation.  Refine-
ments within a cycle can be considered, such as addition of wastewater
during ANOXIC to increase denitrification rate, or a short  aeration period
after ANOXIC to provide dissolved oxygen and remove nitrogen bubbles adhering
to the activated sludge before SETTLE.
                                     732

-------
co
CO
                                       VARIATION OF MLSS
                                                                         .•
                                                                     _^^^



                                         -(-	REACT	^SETTLE^I . \ . | Jl^


                                                                  DRAW
                                                         [-SLUDGE BLANKET-^!
                                        HOURS INTO CYCLE
                         Figure 6.   Time Profile of Mixed Liquor Suspended Solids

-------
CO
                      125
                      100
                  u
                  If
                       75
                  *t  50
                       25
                      -O-
                       20
                       10
VARIATION OF O2 DEMAND

               I

               I
                                       -FILL-
                                       AIRON
              *
                                                345


                                                HOURS INTO CYCLE
                            - REACT-


                             AIR ON
                                                                      »o-
                                                                       I
                                             •o
                                             J

                                              8
                                Figure 7.   Oxygen  Uptake Rates in Batch Reactor

-------
NITRIFICATION/DENITRIFICATION
                INSBR
 INFLUENT
   PUMP
   AIR
                       FILL
                              CO2+ CELLS
                                 NO--N
                       CELL SEPARATION
                       DRAW
                        EFFLUENT DISCHARGE
      Figure 8.  Denitrification Cycle for SBR
                    735

-------
Sizing SBR Processes

   Ketchum,  et al.  (16),  Irvine and Richter (12), and Irvine, et al.  (17),
provide design equations for sizing sequencing batch systems.  These calcula-
tions show that sequencing batch systems can be designed with considerably
less total volumetric requirements than continuous flow processes due to
inherent  equalization, plug flow hydraulics and elimination of external
clarifiers.   Designs can be based on constant influent flow, constant sub-
strate concentration or variable flow, variable concentration, with these
parameters either in or out of phase.

OPERATION AND CONTROL OF SEQUENCING BATCH REACTORS

Sequence Control

   A three-tank SBR system could be operated under the regime given in
Table 3.  In a 24-hour period, Tank #1 would complete two full cycles, with
Tanks #2 and #3 each completing one full cycle.  Effluent would be dis-
charged from one or the other tanks each four hours, and at any one instant,
one tank would be in the FILL mode.
             Table 3- Sequence of Events in a Three Tank System
 Progressive
    Hours
                Tank Number
      1
      2
      3
      4
      5
      6
      7
      8
      9
     10
     11
     12
     13
     14
     15
     16
     17
     18
     19
     20
     21
     22
     23
     24
Fill
React
Settle
Draw
Idle
Fill
React
Settle
Draw
Idle
React
                   Settle
                   Draw
                   Idle
                   Fill
React
                   Settle
                   Draw
                   Idle
                   Fill
                                     Settle
                                     Draw
                                     Idle
                  Fill
                  React
                                     Settle
                                     Draw
                                     Idle
                  Fill
                  React
                                     736

-------
   Control of the mode sequencing could be managed by several routes, depend-
 ing on site conditions or effluent requirements.   Time  clock-solenoids,  set
 by empirical observations, would be  the most simple way to control  in a
 situation where  flow  is relatively constant.  Varying flow situations could
 be managed by a  flow  totalizer on the  influent or  liquid level switches  in
 the tanks to initiate valving changes.  Large variations in substrate could
 be handled with  in-tank, non-specific  probes, such as dissolved  oxygen,  or
 more specific, off-line open-loop control sensors, such as soluble  organic
 carbon.

 Aeration Management

   Any of the above can be mated together for specific  application.  Added
 to this rather complex control strategy is the need to  switch aeration from
 tank to tank or  within a cycle.  These management  functions can  be  very  con-
 veniently programed into microprocessor or process controller units.  In any
 programed operation a SCRAM function is at the top of program hierarchy  to
 oversee total plant control and warn operations staff of out-of-limits events
 (18).

   Since SBR processes characteristically operate with  varying liquid levels,
 aeration efficiency can be reduced due to poor oxygen transfer at reduced
 depths.  As the  discussion of Figure 5 indicated,  aeration can be started at
 the beginning of FILL, at some point during FILL,  or at the beginning of
 REACT.  The biological reaction rate can be controlled  by the oxygen supply
 rate, but in final analysis, enough oxygen must be transferred to satisfy
 the influent mass load of oxygen demand.  Ketchum  (19)  has discussed a step
 supply approach  using two aeration systems of different capacity.   While a
 single aeration  system of constant capacity would  be the most simple to
 control, the stepped approach would be most economical  with respect to capital
 and operating  costs.  In a step air supply design, the larger unit would be
 utilized only to meet the large oxygen demand occurring near the middle  of
 FILL, which is a resultant of the high sludge concentration and  increasing
 organic content  (Figures 5 and 7).  The lesser capacity aeration unit would
 commence at the  beginning of REACT.

 Liquid-Solids Separation

   Australian (10)  experience has shown that sludge bulking is not as criti-
 cal to performance of batch systems as it is to continuous flow  systems.
 The increased surface area and quiescent conditions, compared with  a con-
 tinuous flow clarifier, allows sludge of significantly  poorer settleability
 to be accommodated.  Mixed liquor concentration is much easier to control in
 batch systems because during SETTLE, there is less solids flux and  the
reactor sludge concentration during FILL or REACT does  not depend on a recycle
 flow.

   Irvine  (20)  has  commented on how this feature of batch process could  im-
prove municipal compliance and provide appropriate technology for developing
nations.
                                      737

-------
    Variable  water  levels during  the various modes  of  a  cycle  in  SBR's  require
 special  attention  to decant devices which are activated during DRAW.   These
 can range  in form  from a  submerged outlet pipe with automated valves,  weir
 troughs  connected  to flexible couplings,  floating  weirs, movable baffles,
 tilting  weirs or floating  submersible  pumps.   The  two common  features  of all
 these  approaches are provision for scum control and insuring  effluent  take-
 off is uniformly distributed across the tank.   This latter provision  is
 necessary  since  the  DRAW mode is the peak hydraulic flow within  the cycle
 and short  circuiting could cause uncontrolled suspended solids loss.

 APPLICATION  OF BATCH TREATMENT TECHNOLOGY

 Commercial Wastewater

    Witherow,  et  al.  (21) has  described  the conversion of an anaerobic
 lagoon,  of earthen construction,  into an  extended  aeration SBR for  treatment
 of  meat  packing  wastewater.   Hydraulic  flow was  about 75 m3/d  (20,000  gpd)
 and occurred  in  a single 8  hour  period  during  the  day,  for 6  days each
 week.  Conversion was  accomplished by installing a floating aerator and
 submerged  automated  outlet  valve, both  controlled  by  sequence  timers.
 Sludge wasting was done manually.

    The cycle  employed  was:

              Aerated  FILL and  REACT        18  hours
              SETTLE                         2  hours
              DRAW                           H  hours

    The process conditions were:

                  F/M                 0.06 kg  BOD5/kg MLVSS/d
                  Detention time           10  days
                  SRT                      64  days
                  MLSS                     3,350 mg/1
                  SVI                        217 ml/g

   The efficiency was evaluated  for one year.  The  yearly average values
 for influent  and effluent are given in  Table 4.  The average data indicates
efficient  pollutant removal with  the exception of  rather high  total suspended
solids (TSS)  in  the effluent.  These average data  are not indicative of
actual performance since the TSS  values were near  200 mg/1 during the  two
month startup period, but declined to about 25 mg/1 afterward.

   The long hydraulic detention time and  high  sludge age, coupled with
periodic addition of high strength organic material yielded good nitrifica-
tion and subsequent denitrification.
                                     738

-------
           Table 4.  Batch Treatment of Meat Packing Wastewater
Item
BOD5
COD
TSS
NHij-N
N02+NOo-N
TKN
TP
Influent,
mg/1
714
1,630
535
13
0.4
79
11
Effluent,
rag /I
17
121
65
2
3
8
3
Removal ,
Percent
98
93
88
95
-
90
72
Small Community Wastewater

   Goronszy (22) has reported on sequentially aerated, discontinuous dis-
charge  single tank processes that have minimal operator attention.  Nitri-
fication and denitrification are encouraged in these applications to protect
water quality and for utilization of the hydroxyl ion, produced by the
denitrification reaction, to buffer low alkalinity wastewaters.

   These processes are sequenced by a variable time selector process control-
ler.  Typically, to achieve nitrification and denitrification, a facility
for 4,000 inhabitants would have the following cycle:

             Aereated nitrification period           4.5 hours
             Anoxic denitrification period (mixed)   3-0 hours
             Quiescent settling period               2.5 hours
             Decant period                           0.5 hours

   Process conditions are:

             F/M                           0.05 kg BOD5/kg MLSS/d
             Detention time                1.7 days
             MLSS                          5,000 mg/1
             SVI                           140 ml/g

   The effluent quality from a facility of this type is shown in Figure 9.

   Estimates of the relative cost of the various components of a sequentially
aereated continuous flow system are estimated by Goronszy (21) to be as
follows:
                                     739

-------
               SEQUENTIALLY
          AERATED BATCH SYSTEM
  01
  o
  u.
    so r
    20
     10
                    BOD5
                        • TOTAL
                         NITROGEN
       2    1O       SO       90     99

        PERCENT EQUAL TO OR LESS THAN
Figure 9.   Effluent Quality of Sequentially Aerated,
           Discontinuous Discharge Batch  Reactor
                     740

-------
             Component                     Percent of Total

             Aeration tank                        53
             Aeration and mixing system           32
             Decant and control system            15

Rural SBR Systems

   Individual onsite SBR's with effluent dispersion systems have  been con-
structed in the Washington, D.C. area since 1975  (23).  An ordinary concrete
septic tank, or other suitable tank, connected to a dwelling by gravity
piping, is fitted with air diffusers.  A timer controlled panel board
sequences a pump, blower, level control and alarm sensor.  The usual cycle
is 20 hours of aeration and mixing, as daily household activities fill the
tank.  At approximately 2:00 a.m.  (0200 hr), the blower stops and the contents
settle for 3 hours.  The pump then directs the supernatant to the disposal
system, such as a mound, trench or evapotranspiration bed.  Since effluent
is only pumped once per day, the effluent disposal system has a wet and
drain cycle which allows aerobic conditions to prevail.

   This type batch process has also been applied to institutional and com-
mercial establishments.  Several proprietary firms, such as Flygt Corp.
(Norwalk, Conn.) and Environment/One Corp. (Schenectady, N.Y.), have
marketed small batch systems.  A typical unit, marketed by Eastern Environ-
mental Controls, Inc. (Chestertown, Md.) is shown in Figure 10.

Municipal Application of SBR's

   There is a reluctance to installation of batch processes at municipal
sites due to the lack of contemporary experience for review by consultants
and state regulatory offices.  As noted in the Introduction, this approach
to wastewater treatment can be considered archaic in view of the  22,000
continuous flow municipal facilities now installed in the United  States.

   Recognition of the virtues of SBR's and the emergence of reliable process
control hardware lead the USEPA to fund a development project, conducted by
The University of Notre Dame, to re-evaluate municipal batch treatment.
The project involved the conversion of the existing 1,500 m3/d (0.4 mgd)
Culver, Indiana, continuous flow activated sludge facility into a two-tank
SBR.   The new flow scheme is the same as shown in Figure 4.

   Primary effluent is directed to each tank on an alternate basis as dicta-
ted by liquid level sensors in each tank.  Pneumatic compression  pinch
valves control tank switching.  Aeration and mixing are provided  by direc-
tional jet aerators.  Effluent is decanted during DRAW by submersible pumps
attached to flotation devices which are swivel mounted to allow changes in
elevation of the pump suction.  All these functions are programmed into a
process controller which operates and monitors all aspects of treatment.

   The controller programs for both Tank-1 and Tank-2 operate independently
in order to have greater mode flexibility within a cycle.  However, a Main


                                    741

-------
-fa
no
               Key:
1 Control panel
2 Air intake
3 Air filter
4 Blower
5 Effluent line
6 Junction box
7 Influent line
8 Alarm sensor
9 Pump shut-off
10 Pump
11 Air-diffusers
                                                              Concrete Tank

                                                                Installation
                                                                                                     ®
                                                                                                       o o
                                                                                                       T
                                         Figure 10.  Rural Aerobic  Batch Unit

-------
program monitors the Tank-1 and Tank-2 programs, on a time-sharing basis,
to insure correct sequencing.  A SCRAM program overrides all three programs
to warn of unprogramed events or emergency valving changes.

   The initial evaluation at the Culver facility used an anoxic period for
part of the FILL mode and this was programed into the controller as FILL-1
and FILL-2.  During FILL-1 only the mixing action of the jet pumps was
activated.  During FILL-2 the jet pumps mixed and aerated simultaneously.
A typical cycle for the two tanks was as follows:

                                      Hours in Mode

Tank-1
Tank-2
FILL-1
1.1
1.2
FILL-2
1.8
1.9
REACT
0.8
0.6
SETTLE
0.8
0.8
DRAW
0.7
0.6
IDLE
0.8
0.9
The difference in times between the modes of the two tanks is due tr- diurnal
flow variation, since the system is controlled by liquid level sensors.  At
the design flow of 1,500 m3/d (0.4 mgd) each cycle is completed in 6 hours
and both tanks complete 4 cycles each day.

     The process conditions at Culver are:

              F/M                   0.2 kg BOD5/kg MLSS/d
              SRT                   20 days
              MLSS                  2,200 mg/1 (70 percent volatile)
              SVI                   110 ml/g

One year of data and operational experience has been documented for 8005
and SS control.  Table 5 provides monthly average wastewater and SBR effluent
constituents for the month of March 1981.  The City of Culver has an effluent
phosphorus limitation of 1 mg/1.  To achieve removal of phosphorus, ferric
chloride is dosed directly into the primary effluent channel leading to
Tank-1 and Tank-2.

   Very high efficiency for BODg, SS and TP is achieved at Culver with the
SBR process.  Nitrate nitrogen of about 2 to 5 mg/1 is usually present in
the Culver raw wastewater due to run-off from fertilized farm land infiltra-
ting sections of the collection system.  Table 5 shows that this influent
nitrate is denitrified during the anoxic FILL-1 mode of the SBR.

     Process conditions to achieve nitrification and denitrification have
recently been implemented.  The anoxic period for FILL-1 has been reduced
to provide a longer period of dissolved oxygen supply for nitrification.
The efficiency of the SBR process during the month of August 1981 is given
in Table 6.

     Nitrification and denitrification occur almost simultaneously, as evi-
denced by the fact that neither ammonium or nitrate nitrogen reach high
concentrations in the reactors.  Apparently as ammonium nitrogen is trans-

                                    743

-------
 formed to nitrate,  during the low load period at the start of FILL, there
 is subsequent denitrification due to the high mixed liquor concentration
 and differential D.O.  content of the reactor.  When mixed liquor is pumped
 through the aerated jet nozzle a high D.O.,  suitable for nitrification is
 present; then as the mixed liquor circulates as a bulk liquid localized low
 D.O. conditions can occur.

      Once nitrification is established in the Culver SBR ammonium nitrogen
 concentration in the reactor can never reach influent levels due to the
 dilution of influent by the residual reactor contents left after IDLE, and
 the biological transformation to nitrate.  Accordingly, the nitrate concen-
 tration cannot reach high levels, and even a low kinetic rate for denitrifi-
 cation would yield  fairly efficient nitrogen removal.

      During the remainder of the demonstration a more detailed evaluation
 of nitrogen removal capabilities of the SBR will be carried out.

          Table  5.   Constituents  of  Culver, Indiana  Process  Streams
Milligrams per Liter
Location
Raw Wastewater
Primary Effluent
SBR Tank-1
SBR Tank-2
BOD5
173
132
8
9
SS
136
81
7
9
TP
6.3
5.2
0.4
0.4
NHij-N
20
19
19
18
Oxidized
Nitrogen
2.8
2.6
0.4
0.4
Overall Removal,
  Percent
 95
94
94
            Table 6.
Efficiency of Culver SBR for Nitrification
       and Denitrification
Overall Removal,
  Percent
 95
98
84
98
              86
Milligrams per Liter
Location
Raw Wastewater
Primary Effluent
SBR Tank-1
SBR Tank-2
BOD5
118
92
6
6
SS
133
64
3
3
TP
5.8
4.8
0.9
1.0
Nfty-N
16.5
14.0
0.3
0.4
Oxidized
Nitrogen
1.7
1.7
1.7
1.2
                                     744

-------
   Several new municipal facilities, at about the 3,785 nP/d scale, are
being constructed under the Innovative/Alternative section of the USEPA
Construction Grants Program.

FUTURE DEVELOPMENT OF SBR TECHNOLOGY

1.  All prior SBR technology has been with systems that are basically low-
rate, long SRT operations.  An effort should be to evaluate this technology
under high hydraulic and organic loadings to obtain a wider band of design
data for 6005 and SS removal.  This is necessary to fully evaluate the
position of SBR technology in the municipal area.

2.  Theoretically, any internally staged process for biological phosphorus
removal, such as Air Product's Anaerobic/Oxic or the Bardenpho process of
Envirotech, Inc. could be designed as an SBR.  Bench-scale studies have
shown feasibility of this approach (24).  Design would be much simpler
since only overall tankage capacity needs to be known.  Modification of
cycle times could provide most efficient treatment as operation was optimized,

3-  Treatment plant internal recycle streams are relatively small in volume
but high in strength.  Treatment of these streams in an off-line SBR
process could upgrade the effluent quality of many facilities.  This same
situation relates to leachates from landfill operations which produce a low
volume, high strength discharge.  Since the character of leachate changes
with age of the landfill modification of the modes in a cycle could account
for changing strength or quality.

4.  Use of SBR's to serve as an equalization process would utilize a cycle
that had only FILL and DRAW modes.  An SBR could serve to equalize both
flow and organic loading prior to a continuous flow process.  Combined
sewer overflow is an obvious candidate for application.

5.  SBR's can also be envisioned as tertiary processes.  Bench-scale work
indicates that lower residuals of phosphorus can be achieved with the SBR
approach compared with continuous flow systems (25).

   Due to more efficient contact and high utilization of precipitant, less
chemical was required and consequently less sludge was produced.

   The possibility of monitoring the effluent for a specific component's
residual before discharge is an attractive feature of this approach.

6.  Presently SBR technology utilizes electro-pneumatic-mechanical valving
for flow control or flow switching.  With microprocessor control, these
functions may be amenable to fluidic devices that contain no moving compo-
nents.
                                     745

-------
REFERENCES

 1.  Sidwick, J. M. ,  and Murray, J. E. ,  "A Brief History of Sewage Treatment
    (Part 1)."  Effluent and Water Treatment Jour., Feb., 65 (1976).

 2.  Hurley, J. , "Contact Aeration for Sewage Treatment."  The Surveyor, 10,
    183 (1943).

 3.  Imhoff, K. , and  Fair, G. M. ,  Sewage Treatment.  John Wiley and Sons,
    Inc., New York,  N.Y. (1940).

 4.  Ardern, E. , and  Lockett, W. T. ,  "Experiments on the Oxidation of Sewage
    without the Aid  of Filters."  Jour. Soc. Chemical Ind., _33_, 523
 5. Ardern, E. ,  and Lockett, W. T., "The Oxidation of Sewage without the Aid
    of Filters.   Part III."  Jour. Soc. Chemical Ind., 34, 937  (1915).

 6. Alvord, J. W. ,  "Sewage Purification Plants."  Jour. Western Soc. of
    Engineers, VII, No. 2, 113 (1902).

 7. Personal Communication.  Eckmann, D. E., Alvord, Burdick and Howson
    Engineers, Chicago, Illinois, 60606, June (1981).

 8. Tchobanoglous ,  G. ,  Wastewater Engineering :  Treatment Disposal Reuse .
    McGraw-Hill, Inc.,  New York, N.Y. (1979).

 9. Pasveer, A., "A Case of Filamentous Activated Sludge."  Jour. Water  Poll.
    Control Fed., 41, 1340 (1969).

10. Goronszy, M. C. , "Intermittent Operation of the Extended Aeration  Process
    for Small Systems."  Jour. Water Poll. Control Fed., 51, 274  (1979).

11. Irvine, R. L.,  "Sequencing Batch Reactors - An Overview."   Jour. Water
    Poll. Control Fed., 51, 235  (1979).

12. Irvine, R. L.,  and Richter,  R. 0.,  "Computer Simulation and Design of
    Sequencing Batch Biological  Reactors."  31st Industrial Waste Conference,
    Purdue University  (1976).

13. Ketchum, L.  H.  , Irvine, R. L. , and  Dennis, R. W. ,  "Sequencing Batch
    Reactors to Meet Compliance."  AIChE Symposium Series, Water  - 1978, No.
    190, 75, 187 (1979).

14. Goronszy, M. C., and Barnes, D. , "Sequentially Operated Biological Systems
    for Bulking Control."  Process Biochemistry, Oct. /Nov., p.  42  (1980).

15. Hoepker, E.  C.  , and Schroeder, E. D. ,  "The Effect  of Loading  Rate  on
    Batch Activated Sludge Effluent Quality."  Jour.  Water Poll.  Control
    Fed., 51, 264  (1979).
                                      746

-------
16. Ketchum, L. H., Liao, P., and Irvine, R. L.,  "Economic  Evaluation  of
    Sequencing Batch Biological Reactors."  33rd  Industrial Waste  Conference,
    Purdue University  (1978).

17. Irvine, R. L., Fox, T. P., and Richter, R. 0.,  "Investigation  of Fill
    and Batch Periods  of Sequencing Batch Biological  Reactors."  Water
    Research, 11, 713  (1977).

18. "Proceedings of the Workshop on Decentralized Systems for Management of
    Water, Solid and Liquid Wastes."  University  of Notre Dame,  Sponsored  by
    Nat. Sci. Found.,  pages 70-81 (1980).

19. Ketchum, L. H., "Flexible Operation of Intermittent Systems."   AIChE
    Symposium Series,  Water - 1979, No. 197, 76,  301  (1980).

20. Irvine, R. L., "The Use of Periodic Biological  Reactors in Developing
    Nations."  International Symposium on Management  of Industrial Wastewater
    in the Developing  Nations, Alexandria, Egypt, March (1981).

21. Witherow, J. L., Tarquin, A. J., and  Rowe, M. L.,  "Manual of Practice:
    Wastewater Treatment for Small Meat or Poultry  Plants." Corvallis,
    Oregon Field Station of Industrial Environmental  Research Laboratory,
    USEPA (1971).

22. Goronszy, M. C., and Irvine, R. L., "Denitrification in Continuous-Flow
    Sequentially Aerated Activated Sludge System, and  Batch Processes."
    International Seminar on Control of Nutrients in  Municipal Wastewater
    Effluents, Volume  3, 71, San Diego, Calif., Municipal Environmental
    Research Laboratory, Cincinnati, Ohio, USEPA  (1980).

23- Kamber, D. M., "Proceedings of the Workshop on  Decentralized Systems for
    Management of Water, Solid and Liquid Wastes."  Rural Treatment Summary
    Report.  University of Notre Dame, Sponsored  by Nat. Sci. Found.,  pp
    19-61 (1980).

21. Barth, E. F., Ill, "Biological Removal of Phosphorus in an SBR."  Masters
    Thesis, Dept. of Civil and Environmental Engineering, University of
    Notre Dame (1981).

25. Ketchum, L. H., and Liao, P., "Tertiary Chemical  Treatment for Phosphorus
    Reduction Using Sequencing Batch Reactors."   Jour. Water Poll. Control
    Fed., 51, 298 (1979).
                                      747

-------
   ANAEROBIC TREATMENT OF MUNICIPAL WASTEWATER
Irwin Jay Kugelman,  Chief,  Pilot & Field Evaluation
    James A. Heidman,  Urban Systems Management
     Donald Brown,  Test & Evaluation Facility
   Municipal Environmental Research Laboratory
                Cincinnati, Ohio
  This  paper has  been  reviewed in  accordance with
  the U.S.  Environmental  Protection Agency's peer
  and administrative review policies and approved
  for presentation and publication.
           Prepared for Presentation at:
        8th United States/Japan Conference
                       on
           Sewage Treatment Technology

                   October 1981
                 Cincinnati, Ohio
                       749

-------
                  ANAEROBIC  TREATMENT OF MUNICIPAL WASTEWATER

              Irwin Jay Kugelman,  Chief Pilot & Field Evaluation
                  James A. Heidman,  Urban Systems Management
                   Donald Brown,  Test  & Evaluation Facility
                  Municipal  Environmental  Research Laboratory
                     U.S. Environmental Protection Agency
                               Cincinnati, Ohio
ABSTRACT
    Application of anaerobic biological processes to the treatment of dilute
wastes at ambient temperature appears economically feasible through the
application of the fluidized bed reactor concept.  When applied to municipal
wastewater, cost savings of approximately twenty percent appear possible
because of the significant reduction in secondary sludge levels and lower
power requirements.  Preliminary data from a small pilot plant is presented
here.  Excellent suspended solids removal has been achieved but organic
removal has not met secondary standards.
INTRODUCTION


    It has been realized for many years that anaerobic biological treatment
systems have significant advantages over aerobic systems.  These include the
low yield of biological sludge per unit of organics stabilized, the
productions of methane (an energy rich end product), and lower operational
power requirements (no oxygen supply is required).  Until recently these havj
been manifest as economic advantages only in situations where the waste
contained high concentration of organic material.  The primary reason has been
the exclusive use of the complete mix-suspended growth - no recycle reactor
concept.  In order to achieve high efficiency with such reactors, large
reactor volumes are required, as well as operation at elevated temperatures.
The large reactor volume insures a high biological solids retention time (SRT)
when no recycle is used, since a long hydraulic detention time is also
provided.

    Recently, film flow reactors have been successfully applied to anaerobic
treatment of wastes of moderate strength at room temperature  (1, 2).  In such
systems, the waste is passed through a reactor packed with a  stationary inert
medium.  The microorganisms attach to the packing and are retained in the unit
thus providing for very long SRT values.  These units, however, do not appear
suitable for dilute wastewater at ambient temperature, i.e.,  domestic sewage.


                                   750

-------
Various studies with municipal sewage have yielded effluents which do not
meet secondary effluent standards at detention times below 12 to  24 hours
(3, 4, 5,  6, 7, 8).  In these reactors, solids removal appears to be the
major mechanism operative when treating municipal wastewater.

    The problem with the fixed film reactor type referred to above may be
that the spaces in the packing have to be so large to prevent plugging that
good contact between the microorganisms and the soluble organics  in the
bulk liquid cannot be obtained in a short detention time.  A reactor type
which obliviates this problem is the fluidized bed or expanded bed.*  In
this system (Figure 1) flow is upward through a packing of small granular
material such as:  filter sand, granular activated carbon, diatomaceous
earth, etc., at a rate sufficient to insure fluidization.  Generally,
effluent recycle is used to achieve a high enough total flow rate to main-
tain fluidization under all conditions.  In this system, as biomass and
solids accumulate in the bed, the degree of expansion automatically changes
preventing plugging.  However, effective mass transfer from the bulk
solution to the microbial surfaces is maintained because the distance
between the surfaces of adjacent media particles is quite small, and the
medium is not stationary but swirls and migrates through the liquid.

    The potential effectiveness of the fluidized bed system for treatment
of dilute wastes versus the stationary packed bed reactor has been demon-
strated in both aerobic and anoxic systems (9).  Successful BOD removal and
denitrification have been achieved in fluidized bed systems at detention
times below 30 minutes.  Recent data to be reviewed below have given promise
that anaerobic treatment of municipal wastewater in fluidized or expanded
bed reactors can produce an effluent which meets secondary standards at
detention times competitive with activated sludge systems.

PRELIMINARY STUDIES ON ANAEROBIC FLUIDIZED BED TREATMENT OF MUNICIPAL
WASTEWATER

    Jewell (10, 11) reported on an upflow expanded bed reactor (Jewell's
terminology) with the support media consisting of a mixture of PVC particles
and ion exchange resin with diameters less than 1 mm.  This laboratory study
utilized a 1-liter reactor with 5.1 cm (2 in) I.D.  After 50 days startup
operation, which included seeding with anaerobic sludge, experiments with
primary effluent as feed were conducted for a period of 200 days.  The
primary effluent was a weak domestic waste with an average effluent COD of
186 mg/1.  Primary effluent was blended with recycle, with the recycle
pumping rate maintained constant at about 100 ml/min.  Except for some
shock loading studies, the temperature was maintained at 20°C.  Effluent
quality was monitored by unfiltered COD and SS measurements.

    During the 200^day study, the hydraulic retention time (HRT) was
varied from 24 hours down to a low of 0.08 hours.  For the first 95 days
the HRT was 4 hours or greater, and after approximately a 20-day period of
*In this discussion, the terms fluidized and expanded beds are used inter-
 changeably, even though there is a technical difference in these terms.


                                  751

-------
                                    EXCESS GAS
   MEDIA SUPPORT
         AND 	
 DISTRIBUTION SYSTEM
                       ,.
                        ;;/.;. FLUIDIZED _ ;.:.v
                       ;•'.'•*   MEDIA" ""•'.;»*»
                        •. •..            «»-_•»
INFLUENT
                                                              EFFLUENT
a
RECYCLE
 PUMP
                                                        s/ss
             Figure  1.   Schematic Diagram of a Fluidized Bed
                        System.
                                   752

-------
operation at HRTs of 2 + 0.5 hours, the HRT was again returned to 8 hours
for several weeks.  During the last ten days of the study the HRT was
varied from 0.25 down to 0.08 hours.  The data indicated that the anaerobic
expanded bed system could treat primary effluent and consistently produce a
secondary effluent of excellent quality (COD of ~ 30 mg/1 and SS of ~ 4
mg/1) when operating at an 8-hour HRT at 20°C.  Good effluent quality was
also obtained during operation at a 4-hour HRT.  The data suggest that long
term operation at HRTs of 1-2 hours may also be possible.

    The effective biomass concentration in the reactor was reported to vary
from 20 to 30 kg VSS/cu m.  The cell yield was estimated at about 0.15 g
VSS/g COD destroyed.  If a reactor removed 150 mg/1 of COD, had a 4 hour
HRT, effluent VSS of 6 mg/1 and a net yield of 0.15, it would take 252 days
to accumulate a biomass concentration of 25 kg VSS/cu m.  Alternatively, if
a reactor were operating at equilibrium with a 4-hour HRT, a reactor VSS of
25 kg/cu m, effluent VSS of 6 mg/1, and no deliberate sludge wasting, the
SRT would be 694 days.  These calculations are intended to illustrate the
long SRTs which are characteristic of the system investigated 1j Jewell.
Although the system produced acceptable effluent quality during the biief
periods of operation at 1-2 hour HRTs, it is not known what would happen
over a long time period if operation were continued under these conditions.
In view of the long SRT's associated with equilibrium operation under a
given set of conditions, the successful operation for a few days at the
high loadings does not ensure that the same effluent quality would be
achieved at the new equilibrium conditions which ultimately develop.

    Switzenbaum and Jewell (12) also evaluated the expanded bed concept in
a laboratory study with a feed of glucose and nutrient salts.  This small
scale study used 5.1 cm (2 in) I.D. columns with a fluidization media of
aluminum oxide particles that were approximately 0.5 mm in size.  The bed
was expanded from an initial volume of 400 ml to an operating volume of 500
ml.  Three reactors were operated at 10, 20 and 30°C, respectively with
steady state feed concentrations ranging from 200 to 600 mg/1 of COD.
Solids concentrations in the reactor were reported between 15,000 to
38,000 mg/1 TVS.  At feed concentrations of 200 and 400 mg/1, the COD
removals resulting from a combination of cell synthesis and CH^ production
were as shown in Table 1.

    These data show that fluidized bed systems are operable over the range
of wastewater temperatures which are encountered throughout most of the
United States.  On the average, about 80 percent of COD removal resulted
from CH4 formation.  Whether results from municipal wastewater treatment
will be comparable to those obtained from glucose at the lower temperatures
has not yet been ascertained.

DESIGN, ENERGY and ECONOMIC CONSIDERATIONS

    Process design of an anaerobic fluidized bed system involves selection
of:  detention time, size and density of medium, recycle flow, expansion
range, overall reactor height, degree of staging.  All of these parameters
are interrelated and their selection will be influenced by capital, energy,
operation and maintenance costs.  At present, only a limited amount of

                                  753

-------
       Table 1.  Soluble COD Removals Reported by  Switzenbaum
                 and Jewell (12).

                            Soluble COD Removal %
 HRT     Feed10°C, mg/1      Feed2°°C,  ing/1          Feed3°°C, mg/1
hours   200       400        200      400             200        400

  6      73        83         83       88              79         82
  4      70        81         74       86              72         83
  2      55        65         72       81              66         77
  1      50        54         57       67              61         70
                                 754

-------
theoretical and practical information which can aid in making these selections
is available.  In this section a brief review of the information is given.

Fluidization
    Extensive studies have been conducted on fluidization and expansion of
beds of granular material.  A review of most of the data has been presented by
Cleasby & Brunann (13). Figure 2 illustrates the effect of particle size and
specific gravity on the upflow rate required for fluidization by water at 2
different temperatures.  This figure is based on the equations presented in
the above review.  Figure 2 is only applicable to clean particle systems.  In
actual practice the growth of a bacterial film on the inert particle will
change its hydrodynamic characteristics.  Figure 2 can be used to make a
preliminary judgment on the specific gravity and particle size to be used for
a given range of hydraulic retention times, bed depths and recycle ratios.


Effect of Bacterial Film
    Changes in particle characteristics resulting from bacterial growth will
impact fluidization characteristics of the bed.  The degree of impact can be
estimated by calculating changes in bed characteristics which would result
from a uniform coating of bacterial growth of different thicknesses developing
around spherical support media.  The results of such calculations for one set
of assumed parameters is shown in Table 2.  A bacterial specific gravity of
1.50 (dry weight basis) with a film concentration of 0.15 gm/cu cm represents
a bacterial film with an apparent specific gravity of 1.05 (0.15 + (1. -
0.15/1.5)).  One of the most interesting observations in the study by
Switzenbaum and Jewell (12) was the extremely thin bacterial film thicknesses
encountered.  Film thickness was estimated by viewing the particles under a
light microscope with a calibrated ocular.  The thicknesses ranged from a
minimum of .007 to .014 mm.  It was also reported that the unattached
entrapped biomass comprised between 4 to 6 percent of the total biomass
present.  Thus a film thickness of .015 mm was used in the calculations on
Table 2.  The changes resulting from 0.015 mm assumed bacteria thickness in
Table 2 indicate that the thin dense films reported by Switzenbaum and
Jewell (12)should have very little impact on the fluidization
characteristics of the bed as a whole.  For example, the 15 micron film
modeled in Table 2 would decrease the fluidization velocity of a 0.5 mm
particle by only 0.52 m/hr (1.7 ft/hr) i.e., from 10.03 m/hr (32.9 ft/hr) to
9.51 m/hr (31.2 ft/hr).

    However, for anoxic dentrification systems Jeris (14) reported that 0.65
mm activated carbon particles reached sizes of 3 to 4 mm as a result of
accumulations of biomass.  The influence that various film thicknesses would
have on the support particles and the resulting changes in the bed
characteristics in the absence of some positive mechanism to limit the
particle size can be discerned from Figure 3.  This Figure is also based on
the same model for spherical particles that was used in Table 2, although some
of the parameter estimates are different in this example.  These results

                                      755

-------
            0.8  V.O   1.1-

    PARTICLE  DIAMETER,  MM
o>»  o.fe   c.e   i.o  t.-z
PARTICLE DIAMETER, MM
Figure 2.  Fluidization Velocity vs.  Particle Diameter
           at Different Specific Gravities.
                          756

-------
                                     Table  2.   Fluidized  Characteristics  for  Spherical  Particles
in
INITIAL  VALUES:
   Particle Diameter, mra
   Particle Volume,  cu m
   Particle Mass, mg
   Particle Number Per Liter
   Fluidizatlon Velocity, gpra/sq ft
   Huldlzatlon Velocity, ft/hr
   Reynolds Number
   Fluidizatlon Head Loss, ft/ft

FINAL VALUES:
   Particle Diameter, mm
   Particle Volume,  cu mm
   Particle Specific Gravity
   Particle Mass, mg
   Unexpended Particle Number Per Liter
   Bacteria In Unexpanded Bed, ng/1
   Ratio of Unexpanded Bed Volumes
   Flutdlzatton Velocity, gpm/sq ft
   Fluldlzation Velocity, ft/hr
   Reynolds Number
   Head  Loss Per ft  of Media
      Initially Present, ft
   Bacteria Per Liter of Media
      Initially Present, kg
20.0 Degrees C
Media Specific Gravity 	
Bacteria Specific Gravity 	


Initial Porosity of Unfluldized Bed 	
Final Porosity of Unfluldized Bed 	
0.20 0.30 0.40 0.50
0.0042
0.0111
1.43x108
0.773
6.20
0.1049
0.990
0.230
0.00637
2.102
0.0134
9.42xl07
3.08x10*
1.521
0.6821
5.472
0.1064
0.0141
0.0374
4.24xl07
1.617
12.97
0.329
0.990
0.33
0.0188
2.252
0.0424
3.19xl07
2.24x10*
U331
1.484
11.90
0.3321
0
0
1
2
21
0
0
0
0
2
0
1
1
1
2
20
0
.0335
.0888
.79xl07
.729
.89
.741
.990
.43
.0416
.338
.0973
.44* 107
.76x10*
.242
.556
.51
.7456
0.0654
0.1734
9.17xl06
4.097
32.86
1.389
0.990
0.53
0.0779
2.393
0.1866
7.70xl06
1.44x10*
1.191
3.886
31.17
1.397
2.650
1.500
0 015
0 150
0 400
0.400
0.60
0.1131
0.2997
5.31X106
S.709
45.79
2.323
0.990
0.63
0.1309
2.432
0.3184
4.58xl06
1.23x10*
1.158
5.461
43.81
2.334






0.70
0.1796
0.4759
3.34xl06
7.557
60.62
3.588
0.990
0.73
.2037
2.461
0.5012
2.95xl06
1 .06x10*
1.134
7.275
58.35
3.602






0.
0.
0.
2.
9.
77.
5.
0.
0.
0.
2.
0.






80
2681
7)04
24x106
637
30
229
990
83
2994
483
7433
2.00xl06
9.
1.
9.
74.
5.
41xl03
117
32
75
246






0
0
1
1
11
95
7
0
0
0
2
1
1
8
1
11
92
7






.90
.3817
.011
.57x106
.94
.78
.289
.990
.93
.4212
.500
.053
.42X106
.43xl03
.103
.59
.96
.31






1.00
0.5236
1.388
l.lSxlO6
14.46
116.0
9.811
0.990
1.03
0.5721
2.514
1.438
l.OSxlO6
7.64xl03
1.093
14.08
112.9
9.836
                                                          1.006      0.999      0.997      0.9957    0.9947     0.994      0.993     0.9931     0.9928

                                                          0.0469     0.0297     0.218      0.0172    0.0141     0.0121     0.0105    0.0093     0.0083

-------
en
00
                     MEDIA SPECIFIC GRAVITY
                     BACTERIA SPECIFIC GRAVITY
                     BACTERIA FILM CONCENTRATION
                     INITIAL BED POROSITY
                     FINAL BED POROSITY
                                  MEDIA DIAMETER, MM
                                        O   l.l
                                        D   0.8
                                        A   0.6
                                        O   0.4
1.6
1.3
0.1 GM/CU CM
0.40
0.40
                    0.1      0.2      0.3     0.4
                 BACTERIA FILM THICKNESS, MM
V)
o
  nc
   5
                 §  20

                 I
                 g  15
                 PQ
                 O
                 W
                 g  10
                                                                     50
                                                                     40
                                                                     30
                                                                     20
                                                                                I
                                                                               0.1     0.2      0.3      0.4
                                                                                BACTERIA FILM THICKNESS, MM
                                                                                                          I
                             0.1      0.2     0.3      0.4
                             BACTERIA FILM THICKNESS, MM
      Figure 3.   Influence of Bacteri^ Film Thickness on  Fluidization Properties and Bed Characteristics.

-------
 illustrate  that  in designing fluid bed systems it is important to know the
 nature  and  thickness of  the bacterial growth to be expected.  This will
 influence the optimal media size and density, the amount of bed expansion
 observed, the need to control media—bacteria particle size, and the  importance
 of diffusional considerations within the films in controlling the biofilm
 kinetics (15).
 Recycle Effect on Pumping Energy


     As  an operational expedient, the systems studied by Jewell (10,11) and
 Switzenbaum and Jewell (12) used  a very high recycle rate  to maintain  bed
 expansion.  The recycle rate in  Jewell's system was maintained at  100 ml/min
 which corresponds  to an upward velocity of 70.4 m/day  (1730 gpd/sq  ft).  For
 operation at a 4-hour HRT  the recycle:  influent pumping  ratio was  24:1.
 Switzenbaum and Jewell used even higher recycle flows  (211 m/day or 5200 gpd/
 sq.  ft) for  studies   with the aluminum oxide media.   Although the  fluidized
 bed  system will save energy compared to activated sludge  because no oxygen  is
 added to the reactor, it is clear that the energy savings could be  negated
 through excessive  pumping  requirements.

     The energy required to fluidize a bed of granular  material can  be
 estimated from the head loss required to fluidize the  bed, which is equal to
 the  bouyant weight of the  bed particles.  As an example,  consider a reactor
 containing 3.05 m  (10 ft)  of silica sand of specific gravity  2.65 with a
 porosity of 0.40.  The head loss through the bed is 3.02  m (9.9 ft).  If the
 design  called for  2-hour HRT and no recycle pumping was contemplated, the
 particle sizes would have  to be  exceedingly small (<\>0.2  mm)  to insure
 fluidization; as shown by  the curves in Figure 4.  Assuming a wire  to water
 pumping efficiency of 65%, the energy expended to overcome the headless
 through the bed (excluding the losses in the distribution system) would be

 (3.02 m) (9.806 newton/kg) (1000 kg/cu m)  =  0.0126 kwh/cu m (47.8 kwh/MG)
 (3600  sec/hr) (1000 watt/kw) (0.65eff)

 If the  proposed design called for using sand particles of approximately 1 mm
 size, the minimum  fluidization velocity would increase to 30.5 m/hr (100
 ft/hr)  (Figure 4) and providing  a 2-hour HRT in the 3.05  m (10 ft)  bed would
 require that the recycle:  influent pumping ratio rise to greater  than 19:1 to
 achieve more than minimum  bed expansion.  In this case, the pumping require-
 ments at an overall efficiency of 65 percent would rise to 0.252 kwh/cu m (955
 kwh/MG) of wastewater treated, excluding the additional losses in  the
 distributor system.  The distributor losses will vary  with the type of
 distribution system and flow rates chosen and will probably add an  additional
 0.3  to  1/2 m (1 to 4 ft) of head loss to the system.   The first situation
 above,  i.e. no recycle requires  low pumping energy but could  lead  to
 instability because,  with small particles,  small changes in flow yield large
 changes in degree of expansion.   There is little chance of bed instability
with high recycle but pumping costs may be excessive.
                                    759

-------
       COLUMN 1


             off gas
                                            COLUMN 2
recycle
line

t

expanded
bed
38.5 in.


[
gravel
media
support
22 in.
-+T?\
^W



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•••


•••I




recycl e
pump
"^influent
 feed
 pump
                      reservoir
feed
pump
                         off gas
recycl e
line

t


expanded
bed
49.5 in.

1
gravel
media
support
22 in.
t
/^"^
"*"vO
recycl e
pump


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° 0 ° 0 0
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effluent







NOTE:  Both columns are 6 in. diameter by 120 in. tall cast
       acrylic cylinders.  1 in. = 2.54 cm.


       Figure 4.  Experimental Fluidized Bed Pilot Plant.
                           760

-------
    It can be seen that the energy requirements for fluidized beds will be
determined by the HRT required, the size and specific gravity of the media
selected, and the extent to which the bacterial film characteristics alter the
particles behavior.  For the ,thin films observed by Switzenbaum and Jewell,
silica sand particles of around 0.3 to 0.4 mm size should produce acceptable
fluidization characteristics and bacterial concentrations (Table 2), and
result in
-------
 Methane Production and Recovery

         In contrast to an anaerobic sludge digester where the high sludge
feed concentrations make the amount of City existing in solution negligible
in comparison to the amount which is recovered in the overlying gas phase, the
amount of City which leaves the reactor in a dissolved phase from an
anaerobic fluidized bed reactor can represent a substantial part of the City
formed.

         Methane production from the anaerobic decomposition of any organic
compound can be accurately predicted by a number of techniques.  Symons
developed the following equation:

cnHa°b + (n - a/b - b/2) = (n/2 - a/8 + b/4) C02 + (n/2 + a/8 - b/4) City

    Equal proportions of methane and C02 result from the decomposition of
carbohydrates and also from acetic acid.  Proteins, fats and long chain acids
will yield gas compositions higher in City than C02-  Typical municipal
wastewaters have total organic carbon concentrations (TOCs) in the primary
effluent of 80 to 180 mg/1.  If 85 percent of this TOC were converted to C02
and CH^ in an anaerobic system in the ratio of 40:60, the carbon in the
methane produced would range from 41 to 92 mg C/l.  A comparison of these
values with the methane solubility data in Table 3 shows that in all cases the
quantity of methane produced which exists as dissolved methane gas must be
considered in any design situation where recovery of the methane from the
gaseous space overlying the reactor will be practiced.  These data show that
the amount of City which remains dissolved in the liquid phase can be a
significant fraction of the total City production.  Of course, the partial
pressure of the methane in the gaseous phase will affect the equilibrium
solubility concentration.  Whether the dissolved City concentration will tend
toward the equilibrium concentration dictated by the overlying partial
pressure, remain near the saturation concentrations shown in Table 3, or be
somewhat supersaturated will be influenced by the reactor design, the
hydraulic residence time, and the degree of gas transfer across the gas-liquid
interface.  In contrast to an anaerobic sludge digester with an overlying
atmosphere of 25 to 35 percent C02, the C02 overlying an anaerobic
fluidized bed reactor will be much less.  Assuming influent TOC of 80 to 180
mg/1, the C02 production would be 27 to 62 mg/1 as C.  When these values are
compared to the solubility limits in Table 3 it is clear that the equilibrium
partial pessure of C02 will be quite small.  The actual values will depend
upon wastewater pH and mass transfer across the gas-liquid interface, but
should be less than 10 percent of the off-gas volume.  Also the N2
concentration in the overlying gas volume could be 5 to 15 percent of the
total gas volume because of evolution of the nitrogen gas initially dissolved
in the wastewater.

    Another consideration in estimating methane production is the sulfate
concentration of the wastewater.  The sulfate concentration in natural waters
varies from 5 mg/1 to 250 mg/1^^'.  In anaerobic systems the sulfate can
serve as a terminal electron acceptor in biologically mediated reactions.
This can be represented by the following half

                                     762

-------
TABLE 3-
Temperature
C
10
15
20
25
30
SOLUBILITY OF
Solubility*
29.6
26.0
23.2
20.9
19.0
CARBON
, mg/1
co2
2318
1970
1688
1449
1257
DIOXIDE AND METHANE
Solubility as
f^W **^
22.2
19.5
17.4
15.7
14.3
GASES
C, mg/1
co2-c
632
537
460
395
343
*When the pressure of the gas  plus  that  of  the water vapor  is  760 mm Hg
                                 763

-------
    1^ S04 -2 + 19_ H+ + e~ =_!_ H2S + _1 HS~ + !_ H20
    8          16          16       16       2

    According to Bryant^w, methanogenesis in natural ecosystems does not
occur when sulfate is present.  Conversion of acetate to CC>2 with sulfate
reduction to sulfide is thermodynamically more favorable than acetate
conversion to C(>2 and City.  With wastewaters containing influent COD's of
200 to 250 mg/1 and 804 concentrations of 200 mg/1 (133 mg/1 as 62), the
majority of the organic material could be oxidized through sulfate reduction
with a corresponding decrease in methane formation.  Hydrogen sulfide gas is
extremely soluble in water (3850 mg/1 at 20°C), whereas most heavy metals
form insoluble sulfides.   The partitioning of the H_S gas between the liquid
and overlying gas phase will depend on the distribution of sulfur species and
the degree to which the equilibrium conditions predicted by Henry's law are
approached.

 ECONOMIC PERSPECTIVE
    Application of anaerobic fluidized bed treatment of wastewater envisions
replacement of the activated sludge system with an anaerobic reactor.  This
can potentially result in cost savings in the following areas:  a)  a
reduction in energy demand as air or oxygen need not be supplied, b) a
reduction in capital cost for the secondary system because it may be possible
to use smaller reactors, smaller final clarifiers; and no air supply system
will  be needed, c) all of the organics in the wastewater can be converted to
methane which can be used on site as a fuel or sold to a utility company, and
d) a  reduction of capital and operating costs for sludge handling.  The first
three of these are somewhat speculative and may not yield significant economic
advantages.  The energy reduction resulting from the curtailment of aeration
will  range  from 0.132 to .264 kwh/cu m (500 to 1000 kwh/MG) depending on the
SRT of the  activated sludge system.  However, as illustrated above, perhaps
1/4 to 1/2  of this power will be required to pump the recycle.  Although the
data  presented by Jewell and co-workers^10> l* » *2' indicates successful
operation at HRT lower than conventional activated sludge this must be
demonstrated in a real world situation.  Also to be demonstrated is the
possibility that smaller final clarifiers can be used.  Thus the only sure
saving is that extensive air supply equipment will not be required.  Even this
saving must be modified because  some degree of post-aeration will be needed
with  an anaerobic system to strip sulfides and methane and raise the effluent
dissolved oxygen.  In a conventional treatment plant with anaerobic digestion
for stabilization of both primary and secondary sludge 60 to 70 percent of the
incoming degradable organic carbon can be converted to methane.  With an
anaerobic reactor substituted for the aerobic secondary treatment process,
over  90 percent conversion  to methane should occur.  However, much of the
extra methane will be dissolved  on the liquid and must be stripped under
controlled  conditions to be recovered.  In addition, as indicated previously,
some  of the organics will be stabilized through sulfate reduction which will
reduce  the  methane yield.

    The major economic effect of adaption  of anaerobic treatment will be  the
reduction  in  sludge disposal costs.  Table 4 presents data on  sludge
                                     764

-------
     TABLE 4.   SLUDGE QUANTITIES AND VOLUMES REQUIRING PROCESSING PER MILLION
               GALLONS TREATED IN A TYPICAL ACTIVATED SLUDGE PLANT WITH PRIMARY
               CLARIFICATION

Influent 8005 and Suspended Solids, mg/1 of each
Primary Sludge, Ib
Secondary Sludge, Ib
Unthickened Primary Sludge
Volume at 4% Solids, gal
Thickened Primary Sludge
Volume at 9% Solids, gal
Unthickened Secondary Sludge
Volume at 1% Solids, gal
Thickened Secondary Sludge
Volume at 3% Solids, gal
Case
No. 1
200
1001
636
3000
1334
7626
2542
Case
No. 2
250
1251
837
3750
1667
10036
3345
     Thickened Combined Sludge
       Volume at 5.52,  gal                                  3569     4552

     Primary Sludge Volatile Solids, Ib                      651      813

     Activated Sludge Volatile Solids, Ib                    477      628

Design Assumptions:

Primary Clarifier Solids Removal 60%
Primary Clarifier Sludge 65% Volatile Solids
Primary Clarifier BOD Removal 35%
Cell Yield 0.75 Ib. VSS/lb BOD5 Removed
Cell Decay 0.07 days ~1
Soluble Effluent 8005 3 mg/1
SRT 5 days
Effluent Suspended Solids 15 mg/1
Effluent Solids are 75% Volatile
                                      .765

-------
quantities produced at a conventional treatment plant.   The  preliminary  data
produced by Jewell et.al.'10»  H»  ^^ indicates that an anaerobic  secondary
treatment unit could meet secondary effluent standards  without  any sludge
wasting except the 10-15 mg/1  biomass in the effluent.   It can  thus be  seen
that the sludge quantity in mass and volume is considerably  less  from a
conventional primary plant followed by an anaerobic secondary than from  a
conventional primary plus aerobic secondary plant.   Using the EXEC/OP cost
program,(21> 22) the effect of this reduction in sludge quantity was
calculated for 3,780m3/day (1MGD) and 37,800m3/day  (10MGD) treatment
plants.  For the smaller plant using gravity thickening,  lime stabilizations,
vacuum filtration and hauling  of filter cake costs  are  reduced  by  33 percent
for sludge handling and disposal and by 15 percent  for  overall  plant capital,
operation and maintenance.  For the larger plant using  gravity  thickening,
anaerobic digestion, elutriation, vacuum filtration and cake hauling, costs
for sludge handling and disposal are reduced by 46  percent and  overall  plant
capital and operation and maintenance by 18 percent.  Thus,  use of anaerobic
secondary treatment can leave  a significant effect  on the treatment cost for
municipal sewage treatment.


 SUMMARY


    The results reported by Jewell    '     and Switzenbaum and Jewell
have demonstrated that better than secondary effluent quality can be obtained
from a laboratory anaerobic expanded bed reactor treating primary effluent at
20°C.  The process was also shown to provide good COD removal with a glucose
feed when the temperature was  10°C and the HRT was  4 hours or greater.
Since wastewater temperatures  in much of the United States fall to 8 to 12°C
during wintertime operation, the response at lower temperatures is quite
important.  Previous studies by O'Rourke^3) with homogenized primary sludge
established that methane fermentation was drastically reduced at  15°C and
that efficient digestion could not be accomplished even at a 60-day retention
time.  The lipid fraction of the waste was not utilized.  However, there was a
measurable reduction in the total COD due to the methane fermentation of
formic and acetic acids resulting from cellulose and protein degradation.
Whether or not anaerobic treatment of municipal wastewaters  at  low temperature
is economically attractive has yet to be demonstrated.

    Because of the limited data available, the long time required for such
systems to come to equilibrium, and the scale of the studies reported,  there
are a number of questions related to anaerobic fluidized bed technology which
remain to be answered before the design approach can be optimized.  These
include:  reaction kinetics as a function of temperature; reactor response
under dynamic loading; optimal reactor depth, media density and size; need for
equalization basins and an overall flow control strategy, effect of degree of
bed expansion; net solids production; solids levels attainable  in the reactor;
biological  film properties; effect of biological growth on media expansion
characteristics; solids control strategies in the reactor, if any; need for
final clarifiers; influence of wastewater sulfate concentration on the
desirability and performance of the process; long term process stability and


                                     766

-------
reliability at pilot scale; need for post treatment to remove sulfides,
residual solids and raise dissolved oxygen;  and effect of the transient
presence of toxic materials.


EXPERIMENTAL EVALUATION OF ANAEROBIC FLUIDIZED BED TREATMENT OF MUNICIPAL
WASTEWATER


    In order to gather information on some of the uncertainties listed in the
previous section a small pilot unit was set  up at the Cincinnati Test &
Evaluation Facility.  The prime purpose was  to determine effluent quality as a
function of hydraulic detention time and wastewater temperature with a feed of
primary effluent.  Based on hydrodynamic analysis of fluidization in previous
sections, the medium chosen was -40 to +50 mesh silica and with the system
flow rate set to produce approximately 10 percent bed expansion.  Use of this
medium and flow rate requires pumping power  which is within the range of
economic acceptability.  In addition, the bed height required is not excessive
for the detention times anticipated.  It was decided to start at a low
expansion rate to allow for maximum change in expansion due to biomass coating
of the media.

    A schematic diagram of the final version of the test apparatus is given in
Figure 4.  It consists of two 15.2 cm (6 inch) diameter columns in series each
originally packed with 1.53 m (5 feet) of sand.  Supporting the sand is  graded
gravel used to provide flow distribution.  The sand depth given in Figure 4
reflects losses during system renovation discussed below.  Two independent
positive development pumps are used for each column:  one for the wastewater,
the other for the recycle.  Note that the recycle take off point is below the
effluent discharge point in each column.  Traps are provided to protect  the
pumps against clogging with any media which  escapes the column.  The effluent
line of each column is trapped to prevent escape of gas.  Gas measurement with
a wet test meter is provided.  The details of this design are the result of
several months of trial and error during system start up.  Originally only one
column was used and when a second was added, the same recycle pump was used
for both.  This was abandoned when operational problems developed.  The
location of and size of the traps were changed to avoid problems which
developed during sampling.

    The system was started by seeding with digester supernatant and primary
effluent with the system set on 100 percent  recycle.  Periodically a mixture
of sodium acetate, acetic acid and methanol  was added on a batch basis.
Periodic analyses were used to determine when the system had to be refed.
After several months of operation, during which time the second column was
added, a flow through system was started with primary effluent as the feed.
The hydraulic detention time was gradually reduced from 5 days to 1.5 days
over a 2 month period at which point long term operation was to be initiated.
At that time a crack developed in one of the columns.  The system was shut
down, and the media was removed and stored in a barrel while repairs were
made.  When the system was restarted, methanol was fed to evaluate the effect
of the shutdown and media removal.  Rapid removal of the methanol accompanied
by gas evaluation occurred, indicating that several days exposure to the air
had little effect on the methane bacteria in the biofilm.
                                     767

-------
    Again, just when long term operation was to be started,  an operational
problem developed.  The recycle pump packing sprang a leak,  the columns
drained, and the pump ran dry.  After several days down time,  the pump was
repaired and start-up took place.   It was difficult to fluidize the media at
first and in the process much biomass appeared to be flushed out of the
system.  Despite this, once underway system operation seemed satisfactory.

    For the next four months the system was operated under steady conditions
with the HRT in the range of 1 to  1.2 days.  Table 5 gives data on operating
conditions during this period.  Tables 6 and 7 provide data on treatment
performance.

    It can be seen that suspended  solids removal was good with the effluent
usually meeting the EPA standard of 30 mg/1.  However, organics removal  was
not as good as required for secondary effluent.  Organics removal was not
affected by temperature changes as the column temperature was  20°C in
January and 22°C in April.  The consistency in temperature was due to the
high rate of recycle (100 to 1).  Volatile acids were low generally in the
range of 50 to 100 mg/1, with lower concentrations in the effluent from the
first column.  There was no evidence of gas evaluation from either columns
because either the quantity of methane produced was less than its solubility,
or sulfate reduction accounted for most of the COD decrease.

    In May 1981 the detention time was reduced at 2 week intervals first to 21
hours, then to 17 hours, and finally to 12 hours.  The system was maintained
at this detention time through June 1981.  The performance of the system
remained the same as at the 1 day  detention time:  good suspended solids
removal, modest organics removal,  no evidence of gas production and lower
volatile acids in the first column effluent than the second.  The latter
indicates the possibility that breakdown of the complex organics in the  sewage
is the rate limiting step in the system rather than the methane fermentation
step.  Further evidence of this is that each time the detention time was
reduced in May, the volatile acid  level rose for only one day and than was
reduced to below 100 mg/1.  As indicated in a previous section, at low
temperatures anaerobic breakdown of lipid material is severely retarded.  This
may account for the high level of  organics in the system effluent.


SUMMARY OF EXPERIMENTAL EVALUATION
    To date anaerobic expanded bed treatment of primary effluent at detention
times down to 12 hours has not been able to produce a treatment level which
would qualify for approval as secondary effluent.  Suspended solids levels in
the effluent have been consistently below 30 mg/1 but effluent COD has been
about 25 to 50 mg/1 higher than aerobic secondary effluent at the same plant
site.  The rate limiting step may be volatile acid production from complex
organics rather than methane production.  Methane production rate has not been
high enough to exceed the methane solubility in water.  Long-term stable
mechanical and hydraulic pilot plant operation at conditions envisioned for
field application has taken place.  Biomass accumulation has not affected
fluidization and expansion characterists of the bed of granular media.

                                     768

-------
TABLE 5.      OPERATING PARAMETERS
              ANAEROBIC TREATMENT SYSTEM
              JANUARY - APRIL  1981

Parameter
HRT (days)
Flow (L/d)
Flow (gpd)
Recycle Flow (L/d)
Recycle Flow (gpd)
Bed Expansion (%)
Upf low Rate (L/m2-S)
Upf low Rate (gpm/ft2)
January
1.2
48
12
4800 .
1300
12
3.6
5.3
February
1.0
39
10
4200
1100
6
3.0
4.4
March
1.0
39
10
5800
1500
11
4.4
6.5
April
1.2
35
9
4800
1300
6
3.6
5.3
                 769

-------
       TABLE   6-     EFFLUENT QUALITY
                    ANAEROBIC TREATMENT SYSTEM
                    JANUARY  - APRIL  1981

Parameter
PH
Alkalinity (mg/1 as
TOC (mg/1)
COD (mg/1)
TSS (mg/1)
January
8.0
CaCOa) 600
127
185
37
February
8.1
530
-
104
42
March
8.2
630
78
193
23
April
8.2
520
69
129
30

TABLE 7.      REMOVAL EFFICIENCY (% REMOVAL)
              ANAEROBIC TREATMENT SYSTEM
              JANUARY - APRIL 1981

Parameter
TOC
COD
TSS
January
39
58
80
February
-
71
84
March
44
52
88
April
27
45
75
                     770

-------
REFERENCES
1.   Young, J.C. and McCarty,  P.L.,  "The Anaerobic Filter for Waste Treatment,"
     Technical Report No.  87,  Department of Civil Engineering, Stanford
     University, March 1968.

2.   Mueller, J.A.  and Mancini,  J.L.,  "Anaerobic Filter Kinetics and Appli-
     cation,"  Proc. 30th Purdue Ind.  Waste Conference, 423,  1975.

3.   Coulter, J.B., et al., "Anaerobic Contact Process for Sewage Disposal,"
     Sewage and Industrial Wastes, 29, 468, 1957.

4.   Witherow, J.L., et al.,  "Anaerobic Contact Process for Treatment of
     Suburban Sewage,"  Proc.  American Society of Civil Engineers,  Journal
     Sanitary Engineering Division,  Paper 1849, SA6, November 1958.

5.   Fall, E.B., Jr. and Kraus,  L.S.,  "The Anaerobic Contact Process in
     Practice," Journal Water Pollution Control Federation, 33, 1038, 1961.

6.   Pretorius, W.A., "Anaerobic Digestion of Raw Sewage," Water Research,
     ^, 681, 1971.

7.   Genung, R.K.,  et al., "Energy Conservation and Scale-Up Studies for a
     Wastewater Treatment System Based on a Fixed-Film, Anaerobic Bioreactor,"
     Presented at "Second Symposium on Biotechnology in Energy Production,"
     Gatlinburg, Tennessee, October 1979.

8.   Koon, J.H., et al., "The Feasibility of an Anaerobic Upflow Fixed-Film
     Process for Treating Small  Sewage Flows,"  Presented at "Energy Optimi-
     zation of Water and Wastewater Management for Municipal and Industrial
     Applications Conference," New Orleans, Louisiana, December 1979.

9.   Jeris, J.S., and Owens,  R.W., "Pilot Scale High Rate Biological Denitri-
     fication at Nassua County,  N.Y.," Presented at "New York Water Pollution
     Control Association Winter  Meeting," January 1974.

10.  Jewell, W.J.,  et al., "Sewage Treatment with the Anaerobic Attached
     Microbial Film Expanded Bed Process," Presented at 52nd Annual Water
     Pollution Control Federation Conference, Houston, Texas, October 1979.

11.  Jewell, W.J.,  "Development  of the Attached Microbial Film Expanded Bed
     Process for Aerobic and Anaerobic Waste Treatment," Presented at the
     "Biological Fluidized Bed Treatment of Water and Wastewater Conference,"
     England, April 1980.

                                      771

-------
12.   Switzenbaum,  M.S.  and Jewell,  W.J.,  "The Anaerobic  Attached Film Expanded
     Bed Reactor for the Treatment  of Dilute Organic Wastes," TID-29398,
     National Technical Information Service, Department  of Commerce,
     Springfield,  Virginia,  August  1978.

13.   Cleasby, J.L. and  Baumann,  E.R., "Backwash of Granular Filters Used  in
     Wastewater Filtration," Environmental Protection Technical Series,
     EPA-600/2-77-016,  April 1977.

14.   Jeris,  J.S.,  et al., "High  Rate Biological Denitrification Using a
     Granular Fluidized Bed," Journal Water Pollution Control Federation,
     46, 2118, 1974.

15.   Harremoes, P. "Biofilm Kinetics," in Water Pollution Microbiology Vol. 2,
     edited  by Mitchell, R.  Wiley-Interscience, New York,  1978.

16.   McCarty, P.L., "Anaerobic Waste Treatment Fundamentals IV. - Process
     Design," Public Works,  December 1964.

17.   Symons, G.E.  and Buswell, A.M., Journal American Chemical Society,  55,
     2028,  1933.

18.   Quality of Surface Waters of the United States, 1966, Geological Survey
     Water  Supply Papers 1991, 1992, and 1995, U.S. Department of Interior.

19.   McCarty, P.L., "Energetics  of  Organic Matter Degradation," in Water
     Pollution Microbiology edited  by Mitchell, R., Wiley - Interscience,
     New York 1972.

20.   Bryant, M.P., "Growth of Desulfovibrio in Lactate or Ethanol Media  Low
     in Sulfate in Association with ^-Utilizing Methanogenic Bacteria,"
     Appl.  and Environ. Micro.,  3_3, 1162, 1977.

21.   Rossman, L.A., "EXEC/OP Reference Manual. Version 1.2," EPA Municipal
     Environmental Research Laboratory, February 1980.

22.   Rossman, L.A., "Computer-Aided Synthesis of Wastewater Treatment and
     Sludge  Disposal Systems," EPA-600/2-79-158, 1979.

23.   O'Rourke, J.T., "Kinetics of Anaerobic Waste Treatment at Reduced
     Temperatures," PHD Thesis,  Stanford University, 1968.
                                      772

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NATIONAL SURVEY OF MUNICIPAL WASTEWATERS. FOR TOXIC CHEMICALS
                             by
                       Jesse M. Cohen
                        Lewis Rossman
                      Sidney A. Hannah

                 Wastewater  Research  Division
         Municipal Environmental Research Laboratory
             U.S.  Environmental  Protection  Agency
                    Cincinnati,  Ohio  45268
        This paper has been reviewed in accordance with
        the U.S. Environmental  Protection Agency's peer
        and administrative review policies and approved
        for presentation and publication.
                        Presented at:
              8th United States/Japan Conference
                              on
                 Sewage Treatment Technology

                         October 1981
                       Cincinnati,  Ohio
                              773

-------
NATIONAL SURVEY OF MUNICIPAL WASTEWATERS FOR TOXIC CHEMICALS

Jesse M. Cohen, Lewis Rossman and Sidney A.  Hannah
Wastewater Research Division
Municipal Environmental Research Laboratory
U. S. Environmental Protection Agency
Cincinnati, Ohio 45268
INTRODUCTION

     The modern industrial society manufactures, uses, and discharges to
the environment tens of thousands of chemical compounds that amount to
billions of pounds annually.  It was long known  that some of these chemi-
cals were being discharged to wastewater for treatment at publicly owned
treatment works (POTW).  Further, there was a strong  presumption that some
of these chemicals were incompletely removed and were being discharged with
the effluents.

     Until a few years ago the identification and quantification of the
trace concentrations of organic chemicals in wastewater was beyond the
capability of the analytical techniques of the time.  As more sophisticated
analytical instrumentation and techniques became available, they were quick-
ly applied to wastewater analysis.  In the early and mid 1970's wastewaters
were analyzed for selected classes of compounds.  For example, in 1971,
Reichert, et al.,(l) analyzed for polynuclear aromatic hydrocarbons; Schmidt,
et al.,(2) in 1971 and Lawrence and Tosine (3) in 1976 analyzed for PCB's.
Not until the late seventies were analytical techniques sufficiently advanced
to undertake to analyze wastewaters for more diverse classes of compounds.
Then Chian and DeWalle (4) and Glaze, et al., (5) identified organic com-
pounds which encompassed a wide range of classes of compounds.

     A court imposed Consent Decree issued in 1976  (6) galvanized the
attention of U.S. Environmental Protection Agency on a selected list of
129 compounds (now reduced to 127) including some 114 organic and 13 inor-
ganic compounds.  In the field of wastewater treatment, implementation of
the Decree presented two immediate problems.  First there was the need to
develop the analytical methods capable of analyzing raw wastewaters and
sludges for the diverse classes of chemical compounds represented in the
priority pollutant list; and secondly, there was the imperative need to
establish a base of information on the numbers and  amounts of compounds
received at the POTW, the degree of removal accomplished by various treat-
ment processes and the compounds and concentrations accumulated in the
sludges.

     To meet the above objectives, an EPA funded study was undertaken in
June 1978 by the University of Washington and Georgia Institute of Tech-
nology and had two principal tasks.  The first objective, which was crucial

                                     774

-------
 to completion of the second, was to develop and modify existing analytical
 methods to enable the analysis of raw wastewaters and sludge.  The second
 objective was to obtain information on priority pollutants in wastewaters
 in many plants nationally distributed, to provide a first-step overview of
 the status of priority pollutants in POTWs.   This paper summarizes the re-
 sults of the priority pollutant survey of 25 cities located throughout the
 United States.  Results of the study are described in a report submitted to
 EPA by F. P. DeWalle, E. S. K. Chian, et al., entitled "Presence of Priority
 Pollutants in Sewage and Their Removal in Sewage Treatment Plants." (7)


      Shortly after the initiation of the present study,  a more extensive
 and comprehensive survey was undertaken by the  USEPA Effluent Guidelines
 Division in Washington,  D.  C.   The survey sampled 40 cities with each
 plant sampled for five consecutive days.   Results of a portion of this
 study are described in two  Interim Reports (8,9).

 ANALYTICAL  METHODS DEVELOPMENT

      State-of-the-art  methodology  has  been developed  to measure  priority
 pollutants  in wastewater  and sludge  at  concentrations  previously unattain-
 able  with standard  methodology.   Practical detection  limits derived  from
 minimum measured  concentrations of priority  pollutant  organics were  on the
 order of one  ug/1  except  for pesticides where detection limits were  near
 10  ng/1.

     Low molecular weight  volatile  compounds  were measured using  a modified
 Bellar/Lichtenberg^procedure as shown in  Fig. 1.   In  this  method,  the aqueous
 sample is spiked with one or more recovery/quantitation standards, diluted if
necessary with purgeable organic-free water,  and purged with a stream
 of  organic-free helium.   The gas stream is then  passed through an  inert
 adsorbent trap at room temperature where  the entrained organics  are  retained.
 Upon  completion of  the purging, the  trap  is  heated and back-flushed  with
 organic-free  helium to desorb  the  trapped  organics.  This  sample stream is
 passed directly into a capillary GC  column where it is cryotrapped at
 liquid nitrogen temperatures.  When  all of the sample has  been desorbed
 and cryotrapped, the coolant is turned  off and the cryotrap warmed with a
 flush of hot  air.  The GC or GC/MS analysis  then ensues.

    Recovery  of selected  volatile  priority pollutants  spiked  into  raw
 sewage and into sludge from several  different POTWs are shown in Table 1
 and Table 2,  respectively.  Considerable variation in recoveries is evident
 for individual compounds in different wastewaters and sludges as well  as
 for different compounds in the same  wastewater or sludge.   These differences
 are attributed  largely to matrix effects.  The recovery/quantitation
 standards consisting of deuterated volatile compounds were  added to each
 survey sample before analysis.  The standards were used to compute expected
 retention times to identify the priority pollutants and to  correct for the
 variable recovery of similar priority pollutants.  It was estimated that a
 single analyte quantitated against two internal standards would ordinarily
 vary by 5-10%.


                                     775

-------
PURGE/TRAP SAMPLER
                1/16" STAINLESS
               STEEL TRANSFER LINE
                 GLASS CAPILLARY
                 COLUMN
                      30M SE-54
                    CAPILLARY
                    COLUMN
                                       1/8" COPPER LINE
                                                                    VENT
                                                                     LIQUID'NITROGEN
                                                                     RESERVOIR
         FIGURE  1.  SCHEMATIC OF VOLATILE ORGANICS INSTRUMENTATION USING
                 CRYOGENIC TRAPPING AND CAPILLARY GC/MS SEPARATION

-------
     TABLE  1.   RECOVERY OF  SELECTED VOLATILE PRIORITY POLLUTANTS FROM RAW SEWAGE
                                          FROM FIVE POTW

                                     % Recovery for Listed POTH
'ollutant Spiked
it 20 ug/1
Ethene,
Methane,
Methane,
Ethane,
Benzene
Ethene ,
1,1-Dichloro
Dichloro-
Trichloro-
1,2-Dichloro-

Tetrachloro-
Roch-
ester
70
223
106.5
109.0
89.5
67.5
Akron
139.5
243.5
117.5
104
109
67
Green-
ville
102
59.5
72.5
103.5
97
90.5
Chatta-
nooga
124
133
192.5
109
81.5
240.5
Seattle
94
MO
43
82
90.5
110.5
Mean
Recovery
X
105.9
164.8
106.4
101.5
93.5
115.2
Standard
Deviation
a
26.9
85.0
56.4
11.2
10.3
72.3
NO  =  Not Detected

-------
00
                  TABLE  2.   RECOVERY OF SELECTED VOLATILE PRIORITY POLLUTANTS FROM SLUDGE
                                                     FROM THREE POTW

                                           % Recovery for Listed POTW
Pollutant Spiked
at 20 ug/1
Ethene,
Methane
Ethane,
Benzene
Ethene,
Ethane,
1, 1-Dichloro-
, Dichloro
1,2-Dichloro

Tetrachloro
1,1,2,2-Tetrachloro
Akron
73.5
80.5
89
127
80.5
53.5
Seattle
155
123
142
121.5
66
213
Tacoma
49
188
130.5
115
75.5
119.5
Mean
Recovery
X
92.5
130.5
120.5
121
74
128.5
Standard
Deviation
o
55.4
54
27.9
6.0
7.5
80

-------
      Extractable  priority  pollutant  organics  were  separated  from  aqueous
 samples  in  a  stirred  liquid-liquid continuous extractor  developed at  the
 University  of Washington.   The  resulting  extracts  were further  processed  by
 gel  permeation chromatography,  florisil chromatography,  and  cesium silicate
 coupled  chromatography  to  remove  interferences and to  fractionate the sample
 to  facilitate analysis  for individual  compounds.   Fig. 2 shows  a  simplified
 schematic for separation of extractable organics.  Various solvent exchange
 and  concentration steps have been omitted for clarity of presentation.
 Derivatization with diazomethane  was used to  improve the chromatographic
 behavior of the acidic  compounds.

      Analysis consisted of screening of each  fraction by capillary GC-FID,
 subsequent  recombination of the neutral components, capillary GC/MS analysis
 of  the neutral and derivatized  acid  fractions,  and GC/EC analysis of  the
 neutral  fraction  to pick up low levels of PCB's and pesticides.   The  GC/MS
 data were analyzed by an automated data searching  routine capable  of apply-
 ing  both spectrum matching and  GC retention time criteria for qualitative
 identification, and capable of  either  single-ion or multiple-ion  quantita-
 tion.

      As  with  the  volatile  analyses,  the extractables require extensive use
 of  blank and  recovery samples to  produce  reliable  quantitative  data.   Results
 of  recovery tests for selected  extractable compounds spiked  into  wastewaters
 and  sludges are shown in Tables 3 and  4,  respectively.   In general, recover-
 ies  of extractables were lower  than  those of  volatiles,  particularly  recover-
 ies  from sludges.  Recoveries were also quite variable between  different
 wastewaters for individual priority  pollutants and for different  priority
 pollutants  in the same  wastewater sample.  Appropriate  standards were  spiked
 into  every  sample  to  allow individual  corrections  for the variable recoveries.

SELECTION OF  CITIES

     With some 20,600 municipal treatment  systems  in the  United States, it
was important  that the  small number of cities  that would  be  sampled would
constitute  a  reasonably representative sampling of the country.    The  number
of compounds  and concentrations in municipal wastewater  was  expected  to be
influenced  by  the amount and type of industrial waste discharged  into  the
collection  system.  An  important  criterion for  the selection of the cities
was, therefore, based on an analysis of the industrial discharges  to  POTWs,
differentiated by  flow and  type of industry.

     Industry  in the  United States discharged  a total of 14,1U1 billion gal-
lons of water  per year  (53xl0^5m3) (u.s.   Census 1972) of which 56  percent or
7987 billion gallons/year  (30x10^5ra3) was  untreated.  The major portion was
discharged  to  surface waters of various types  but 7 percent  or 990  billion
gallons/year  (3.7xl0^5ra3) waa discharged  to a  public sewer.  Not  only was
flow considered but also the type of industry  since the  degree of contamin-
ation of the discharged water varies greatly with category of industry.   Pre-
treatment before discharge  by the industry was  also taken  into account.
                                    779

-------
                           FIGURE  2
    EXTRACTION  AND  CLEANUP  SCHEMATIC FOR  PRIORITY  POLLUTANTS
                             SAMPLE
                    LIQUID-LIQUID  EXTRACTION
                 WITH METHYLENE CHLORIDE, PH
           1
                               1
    AQUEOUS PHASE
  ADJUST TO PH 12 AND
EXTRACT WITH METHYLENE
      CHLORIDE
  ANALYSIS:   BASES
                                     1
                         METHYLENE CHLORIDE EXTRACT
                          GPC ON SX - 2 BIOBEADS
                          ELUTE 3 FRACTIONS WITH
                            250 ML 50% METHYLENE
                               CHLORIDE - PENTANE
    _L
  A 1
0 - 80 ML
  DISCARD
            1
          A 2
     80 - 120 ML
 FLORISIL CHROMATOGRAPHY
    ELUTE 3 FRACTIONS
    .WITH 3 DIFFERENT
      SOLVENTS
         PASS THROUGH CESIUM -
           SILICA GEL COLUMN
   I
                                    A 3
                                 ^20-250 ML
                                  ANALYSIS:
                                   NEUTRALS
                     ELUTE WITH
                      METHANOL
  F 1
 14 ML
PENTANE
DISCARD
         F 2
200 ML 50% ETHYL
 ETHER-PETROLEUM
     ETHER
    ANALYSIS:
    NEUTRALS
   F 3
50 ML ETHYL
  ETHER
ANALYSIS:
NEUTRALS
      A 3 s
DERIVATIZE WITH
  DIAZOMETHANE
   ANALYSIS:
      ACIDS
                              780

-------
                     Table  3.   Recovery of Selected Extractable  Neutral  Priority Pollutants
                                            From Spiked Raw Sewage of Four Plants
00
                                            % Recovery for Listed  POTW
Pollutant Spiked at
10 or 20 ug/1
Nitrobenzene
Dimethylphthalate
2,6-Oinitrotoluene
Fluoranthene
Chrysene
Hexachlorobenzene
Winston
Salem
65.0
54.5
68.0
28.0
19.0
67.5
Chatta- Chatta-
nooga nooga
(1st (2nd
Seattle (Sampling) Sampling)
75.5
59.0
69.5
11.5
14.0
17.0
73.5
80.5
42.0
29. .0
54.5
72.0
29.5
16.5
30.0
21.5
30.0
1.5
Peoria
59.5
61.0
67.5
36.0
64.5
116.5
Mean
Recovery
X
60.6
54.3
55.4
25.2
36.4
54.9
Standard
Deviation
0
18.5
23.4
18.2
9.2
22.2
46.2

-------
             Table  4.   Recovery of  Selected  Extractable  Neutral  Priority Pollutants
                                      From Spiked Sludge of Four Plants
                                     % Recovery for Listed POTW
•-J
00
ro
Pollutant Spiked at
50 or 100 ug/1
Di-N-Butylphthalate
Fluoranthene
Naphthalene
Hexachlorobutadiene
Dimethylphthalate
2,4-Dinitrotoluene
Ft. Myers
53.1
53.7
66.8
55.5
68.7
58.1
Greenville
21.5
25.8
72.6
13.8
49.1
37.0
Peoria
14.8
44.0
58.7
75.1
84.0
NF
Winston
Salem
16.8
13.1
23.7
18.5
26.1
20.3
Mean
Recovery
X
26.6
34.2
55.5
40.8
57.0
28.9
Standard
Deviation
a
17.9
18.2
21.9
29.6
25.1
24.7
    NF = Not Found

-------
      A further criterion was based on the size of the plants and geographical
 location.  Plant sizes ranged from 3-5 mgd (13,200 m3/day) to 309 mgd
 1,170,000 mVday) while the percentage of industrial flow varied from 0 per-
 cent to 60 percent.  A frequency distribution plot of plant size and percent-
 age industrial flow, Figure 3, compares the 25-plant study with an EPA survey
 made in 1978 which inventoried 586 plants discharging >^ 5 mgd (18,925 mV
 day or more).  The 25-city survey compares quite well with the much larger
 EPA survey especially when allowance is made for the additional criteria used
 in making the selection.

      The POTW selection also sought to obtain cities with varying death rates
 on the presumption that the high incidence of cancer and lung diseases would
 be expected to have a high number and concentration of priority pollutants in
 their wastewater.  And finally, POTW selection considered the type of treat-
 ment process.  While the majority of the plants used activated sludge, three
 employed trickling filters and four used aerated lagoons or algal ponds.  One
 of the POTWs practiced land spreading.  Twelve of the 25 plants had combined
 sewers.

 SAMPLING PROCEDURE

      In the plant survey single 24-hr composite samples were taken from the
 influent, primary effluent and final effluent.  In those plants that were
 using chlorination an additional sample of the final discharge was taken
 after chlorination.  Grab samples were taken of the sludges of various types
 such as digested, primary, combined, etc.  Nine of the cities were revisited
 for a second sampling, thus the survey consisted of 34 samplings of 25 cities.
 Some 30,000 chemical parameters were determined in the collected samples
 during the survey.

      Since almost half of the priority pollutants are volatile to varying
 degrees - the more volatile compounds having half-lives in open vessels of
 only 20-30 minutes - a sampler had to be devised which would circumvent losses
 of compounds by volatilization during the 24-hr compositing time. Based in
 part on a concept developed in our laboratory, (10) a special sampler was
 constructed and used in the survey.  Sample aliquots were taken proportional
 to flow on a time delay basis related to the  hydraulic detention in the vari-
ous plant units.  The  sampler  is described more  fully by Tigwell, et  al.,  (11).


DISCUSSION OF SURVEY RESULTS

Frequency of Occurrence and Removals in POTWs

     Frequency histograms for the number of priority organic compounds
found in individual wastewater and sludge samples from the different  POTWs
are shown in Fig. 4.  Over a third of the raw wastewater samples  (31%)
contained between 30 and 40 organics at detectable concentrations while 83
percent of the samples contained between 20 and 50 organics.  The maximum
number found in any one sample was 57-  The frequency distribution for the
raw wastewaters is relatively symmetrical.


                                      783

-------
  1000
   100
CD
CO
    10
            O  EPA NEEDS SURVEY OF 586 PLANTS
            A  PRESENT 25 PLANT STUDY
                        50     80  90       99   99,9
                    PERCENTAGE SMALLER THAN
     FIGURE  3.   FREQUENCY  DISTRIBUTION PLOT OF SIZE AND
          PERCENTAGE INDUSTRIAL INFLOW INTO POTWs
                               784

-------
                           37%
c°/
DA

70%


26%

RAW WASTEWATERS
11%

           0   10   20   30   40    50   60
        NUMBER OF PRIORITY ORGANICS DETECTED
                 41%
            16%
                      26%
                           18%
                                  FINAL DISCHARGES
                                3%	22L
           0     10   20    30    40    50   60
                  7%
                                  SLUDGES
                                 12%
5%
           0     10    20    30   40   50   60
FIGURE 4.  DISTRIBUTION OF NUMBER OF  PRIORITY ORGANICS
 DETECTED  IN INDIVIDUAL WASTEWATER AND SLUDGE SAMPLES
                          785

-------
     The final discharge samples are skewed to the lower end in number of
organics detected.   Forty-one percent of the samples had between 10 and 20
priority organics.   Only 6 percent had more than 40 organics present.   Three
quarters of the sludge samples (75?) had between 20 and 40 organics detected.
Again the distribution for the sludge samples is skewed toward the low end.

     Figure 5 compares the number of priority organics detected in each raw
wastewater sample with the total concentration of all priority organics in
the sample.  Each point represents one 24-hour composite sample at a POTW.
The total concentration of priority organics in a sample was calculated by
summing the concentrations of the individual priority organics measured in
the sample.  The majority of samples from the raw wastewaters from the
different cities contained less than 1000 ug/1 (1 mg/1) of priority organics.
Also as previously shown in Figure 4, the number of compounds detected tends
to cluster between 20 and 50.  For those samples containing more than 1000
ug/1 of priority organics, the data indicate that about the same number of
organics are present at higher concentrations rather than a larger number of
organics at normal concentration levels.  It is obvious from the figure that
there is no defined relationship between number and total concentration of
priority organics over all the POTW's.

     Since many priority organics in municipal wastewaters are believed to
be from industrial sources, the number of priority organics in raw waste-
waters was plotted against percent industrial flow as shown in Figure 6.
The solid line is the least squares fit for the points enclosed by the two
dashed lines. There appears to be a generally increasing trend in number
of compounds found with increasing industrial flow.  The coefficient of
determination of this fit is, however, only 0.2.

     No correlation was observed between total concentration of priority
organics and percent industrial flow.  This is most probably due to the
varying nature of the industries and different levels of pretreatment
provided in the cities surveyed.

     The preceding discussion has addressed the numbers and total concen-
trations of organics in individual wastewater samples.  The occurrence of
individual priority organics in the collective data from all POTWs will
now be reviewed. Figure 7 shows the variation in number of individual
organics detected at a specific frequency above concentration levels of 0,
1, 10, and 50 ug/1. Occurrence in raw wastewaters is in the upper graph;
occurrence in final discharges is at the bottom.  An example of how to
interpret the information is shown for the final discharges.  As indicated
by the upper circle, there were 45 individual compounds detected at least
20 percent of the time.  Note that this is not the same as saying that 20
percent of the samples had 45 compounds present since the 45 in question
could be occurring in different samples. Seventeen organics were detected
at least 20 percent of the time at levels higher than 1 ug/1 as shown by
the lower circle.  A total of 79 different compounds were detected in one
or more final discharge samples.  Thirteen were found at least once in
concentrations greater than 50 ug/1.  Only 12 compounds were ever detected
in over 50 percent of the samples and of these only 7 were at levels greater
than 1 ug/1.

                                      786

-------
                        Total Concentration of  Priority Organics,  ug/1

   c
   -t
  : m
o -I
-hO
3 n
O. (D
W 3
   rf

=•2



a I

aco
B> -h
VI
rf -O

21
o> o
r* n
n -••
o> O
3 -i
•o 10

re 3

   n
  "	1
X



 X






X X
                  X

                 XX
X

X  XX

    X

XX
         S--X*	

-------
    60
    50
                                                                            x
                                                                            X
o
«s
o
>>
    40
o
O-
°   30-
   20-
   10-
      0
                  '0
                                                      ~4cT
ar
                              20          30
                                Percent Industrial Flow
    Figure  6.   Number of Priority Organics  Detected  in Raw wastewater Samples
                            v. Percent  Industrial  Flow
                                                                                 6
                                      788

-------
          10
 T3
  O>
  O
  OJ
   20    30   40   50    60    70   80

    Detection Frequency, Percent
                                              96   100
                       Final Discharges
Figure  7 .
   20   30  40   50  60  70   80  90  100

    Detection Frequency,  Percent

Detection Frequencies of Individual Priority
Organics  in  Wastewaters
                           789

-------
     A relatively even spread of detection frequencies was observed for
organics in raw wastewaters.   One compound was detected as much as 95 percent
of the time, 32 were detected at least half the time and 83 were detected
at least once.  Yet only 18 were detected 50 percent of the time at levels
greater than 1 ug/1.  A total of 31 compounds were found at least once in
concentrations greater than 50 ug/1 but none were found at this level more
than 35 percent of the time.

     The detection frequencies for priority organics in sludges, shown in
Figure 8, follow those found for raw wastewaters.  The sludge samples repre-
sent 9 raw primary sludges, 8 raw waste activated sludges, 5 raw combined
sludges, 18 digested sludges, and 2 heat-treated sludges.  Eighty-two com-
pounds were detected at least once, 26 were detected at least half of the
time and one was detected in 89 percent of the samples.  Thirty-three com-
pounds were found at least once in concentrations greater than 50 mg/kg but
only one compound was found in 25 percent of the samples at that concen-
tration.

     Table 5 summarizes the most frequently found compounds at levels of 1,
10, and 50 ug/1 in raw wastewaters and final effluents, and at levels of 1,
10, and 50 mg/kg for sludges.  These include all of the compounds found above
1 ug/1 (or 1 mg/kg) at least 80 percent of the time in raw wastewaters and at
least 50$ of the time in final discharges and sludges.  The total number of
priority organics meeting these selection criteria is only 15. Five are
chlorinated methane or ethane derivatives while four are phthalates.

     The ranges of total concentrations of nine classes of priority organics
in individual raw wastewaters and final discharges are shown in Figure 9.
The upper bar for each class, labeled R, is for raw wastewater; the lower
bar, labeled F, is final discharge.  Identified on each bar are the minimum
reported discrete value, the 25th percentile, the median concentration, the
75th percentile, and the maximum reported value for the selected class and
type of sample.  Because of the wide range of values, a logarithmic con-
centration scale was used.  Total concentrations generally ranged over 3 to 4
orders of magnitude with interquartile ranges (25% to 75%) ranging between 1
and 2 orders of magnitude.  The positions of the medians indicate that the
concentration distributions are skewed to the left with most of the values
at the lower end of the concentration range. Final discharge ranges were
always lower than raw wastewater ranges, however, no conclusions regarding
percent removals should be drawn from Figure 9 since the data do not segre-
gate influent-effluent pairs from a single plant.

     Figure 10 was prepared from single plant influent and effluent data
pairs to show the interquartile ranges of percent removals for the same 9
classes of priority organics.  The left end of each bar represents the 25th
percentile while the right end is the 75th percentile of the data set.
High variablity was observed for the methanes, ethanes, and pesticides.
The wide range of removals for the former two classes can be explained by
the production of chlorinated methanes and ethanes in final discharges
during disinfection with chlorine.  In fact, negative removals are sometimes
observed where final discharge concentrations exceed those in raw wastewater.


                                     790

-------
904
                      Sludges
       10


Figure 8.
 20
30    40     50    60    70

 Detection Frequency, Percent
Detection Frequencies of Individual  Priority Organics
           in Sludges
                             791

-------
—I
<~o
no
                                     TABLE  5.  HOST  FREQUENTLY DETECTED COMPOUNDS  IN RAW HASTEWATER, FINAL DISCHARGE AND SLUDGE SAMPLES



                                                                          PERCENT OCCURRENCE AT INDICATED CONCENTRATION

                                                          RAH HftSTEHATER	         FINAL DISCHARGE	SLUDGEu>
COMPOUND ' l
METHANE, DICHLORO-
METHANE, TRICHLORO-
ETHANE, I.I.-TRICHLORO-
ETHENE, TRICHLORO-
ETHENE, TETRACHLORO-
BENZENE. I.M-DICHLORO-
ETHYLBENZENE
TOLUENE
PHENOL
NAPHTHALENE
PHENANTHRENE
PHTHALATE. DIETHYL
PHTHALAIE. DI-N-BUTYL
PHTHALATE .B i s(2-ETHYLHEXYL )
PHTHALATE, BUTYL BENZYL
ALL OTHERS <
UG/L
83
71
90
90
91
83
87
81
86
86
57
91
89
86
77
80
J 10 UG/L
57
26
61
61
65
37
23
61
66
37
9
57
60
69
60
<60
> 50 UG/L
33
3
16
19
26
6
13
23
31
11
0
17
9
20
11
' 20
i 1 UG/L
79
55
53
17
77
38
13
15
38
21
15
62
85
76
32
'50
J 10 UG/L
m
6
22
16
19
6
3
17
6
3
3
29
18
38
15
'20
i 50 UG/L
28
0
6
3
3
0
0
3
3
0
0
0
3
6
0
< 10
i 1 HG/KG
11
3
5
26
27
36
33
59
63
65
60
13
63
75
50
'5.0
* 10 MG/KG
12
0
3
9
8
18
3
35
25
33
20
23
25
63
35
< 25
> 50 MG/KG
3
0
0
3
3
5
0
11
13
15
8
13
13
25
18
'15
                            EXPRESSED ON  DRY  SOLIDS BASIS.

-------
 ug/1     001
                                          10
                                                     100
                                           1,000    10,000
PHTHALATESi
BENZENES
PHENOLS
METHANES
ETHANES
ETHENES
  PAH'S
N-
COMPOUNOS
PESTICIDES
                            iJ
                                                           mm*
 ug/l    0.01
0.1
10
100
1,000     10,000
          Legend:
            Minimum
        Medi,
                       25t   Median
                              Raw Wastewaters
                         Final Discharges
                           Maximum
     Figure 9 •  Ranges of Total Concentrations of  Nine Classes of Organlcs
                    In Raw Uastewaters and Final Discharges
                                     793

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PHTHALATES
BENZENES
PHENOLS
METHANES
ETHANES
ETHENES
PAH'S
N-COMPOUNDS
PESTICIDES

1 J 1
Median 	 *
•

1 •!

1

•

1 • 1

•

1

1

0 10 20 30 40 50 60 70 80 9 10
Percent Removal
Figure 10.  Interquartile  Ranges of Percent Removals
          for Classes of Priority Organics
                    794

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The wide range in pesticide removals is most likely due to the low concen-
trations of pesticides near the analytical detection limits in wastewaters
and the attendant analytical errors involved.   The use of only 24-hour
composites for calculation of percent removals does not necessarily reflect
the long-term removals at the surveyed plants and will cause some scatter
in the data.  Median removals for benzenes, phenols, ethanes, ethenes, PAH's,
nitrogen-containing-compounds,  and pesticides were all greater than 80 per-
cent.  Of these, the ethenes and PAH's have the most consistent range of
removals.

     Figure 11 was prepared to determine if there was any relationship between
 the total concentrations of priority organics in the raw wastewaters and in
final discharges.  Final discharge concentrations were plotted against raw
wastewater concentrations for 31 plant visits.  The best fit curve through
these data was found to be a power relationship with a coefficient of deter-
mination of only 0.3- Again, the fact that wastewater samples were only 24-
hour composites with very different compositions from plant to plant would
not lead one to expect a quantitative relationship between gross concentra-
tions in and out of different POTWs.  Several individual compounds were also
tested but no relationship could be discerned between influent and effluent
concentrations.

     Because analysis for specific priority pollutant organics is both time-
consuming and expensive, there have been a number of attempts to relate con-
centrations and removals of priority organics to other more common analyti-
cal parameters.   Figure 12 shows a plot of percent priority organics remain-
ing after treatment versus the percent COD remaining.  As observed from the
figure, COD removal is not a good predictor of priority organics removal.
The coefficient of determination of the least squares power function fitted
to these data was only 0.1.

     Paired influent-effluent data from 34 samplings were classified as
being from secondary plants (23 events) or from tertiary plants (11 events).
The tertiary data were from eight separate plants consisting of either acti-
vated sludge, trickling filters, or lagoons followed by either trickling
filters (1 plant), gravity filters (2 plants), lagoons (3 plants), RBC (1
plant), or land application (1 plant).  On average, the percent reduction in
number of compounds detected between the influent and effluent in secondary
systems was 28 percent (0 = 10/£); for tertiary systems, 36 percent (a = 19$).
This difference in reduction in numbers of compounds cannot be called signifi-
cant at either the 5 percent or 10 percent confidence levels.  In terms of
total concentrations of priority organics, secondary plants had an average
of 51 percent removal (Q = 42$) while tertiary plants had an average of 67
percent removal (a = 44/O.  Again, because of the high variability between
plants, it was not possible to call this difference in percent removal sig-
nificant at either the 5 percent or 10 percent level.

Production of Chlorinated Organics

       Where chlorination was practiced, effluent samples before and after
chlorination were examined for both the total number and total concentration
of potential chlorination products.  These included 20 chlorinated aliphatics,

                                    795

-------
            96Z
Final Discharge Concentrations, ug/1

-------
                                        L6L
                          Percent Priority Organics Remaining
10
c
-5
 •o
 ro
 -s
 o
 ro
 3
 -s

 o
 o
 -s
(O
 Qi
 3

 O
X



X
      o_
       CD-
ro
-s
o
ro
3
rt-

O
O
       en
       o-
    n>

    CD
 3  3
ia  ta
 -a
 CO
 -s
 o
 ro
 o
 o
 a
 ro

 CD
       oo
       o-
       8-
                                             CD

                                             I	
                                                           O

                                                           I	
                                                                                 OO
                                                                                 O
                                             X  X
                  -X-

-------
6 chlorinated benzenes, and 4 chlorinated phenols.   On average, 0.73 more
compounds were detected after chlorination than before (a = 3.2) and total
concentrations of the selected compounds increased  68 ug/1 (a = 218).  Given
the variability of these results, it was not possible to discern at 5 percent
or 10 percent confidence levels that chlorinated organics were being produced
by chlorination.

Significance of Priority Organics in Final Discharges

     Concentrations of individual priority organics in final discharges were
compared with proposed USEPA Water Quality Criteria (12) to evaluate their
significance in terms of potential damage to human  health or aquatic life.
The specific criterion selected for comparison for  each compound was the
minimum of the:

     (a)  24-hr, maximum aquatic life criterion

     (b)  Never-to-be-exceeded aquatic life criterion

     (c)  Human health criterion for non-carcinogens

     (d)  Human health criterion for carcinogens based on one induced
          cancer per 1,000,000 people

Comparisons were made with undiluted final discharges and at 1:5 and 1:50
dilutions with receiving waters assumed to contain  no priority organics.
Figure 13 shows the variation in number of priority organics exceeding water
quality criteria a specific percent of the time at  the given dilutions.
For example, there are five compounds that exceed criteria  50 percent of
the time with no dilution of final effluent, two compounds that exceed
criteria 50 percent of the time at 1:5 dilution and no compounds that exceed
criteria 50 percent of the time at 1:50 dilution.

     Note that the number of compounds exceeding a  criterion begins to rise
sharply only when exceedance  frequencies  drop below about 20 percent.  Using
the latter frequency as a cut-off point,  the compounds that are in exceedance
at each dilution level at 20 percent or greater frequency are listed at the
bottom of Figure 13-  There were 22 such compounds  in undiluted final dis-
charges, 15 at 1:5 dilutions, and 6 at 1:50 dilutions.  Compounds included
in this list but not in Table 5 as the most frequently detected compounds
are dichlorobromomethane, 2,4-dichlorophenol,l,2 diphenylhydrazine and
the pesticides.  The pesticides appear here, even though they are present in
final discharges at very low concentrations, because of the highly restric-
tive water quality criteria for those compounds.
                                     798

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     55-t-
   Figure 13.  Number of Priority Organic Compounds
    in Final Discharges Exceeding EPA Water Quality Criteria
                     at Different Dilutions
             10
         20    30    40    50    60    70
           Exceedance  Frequency, Percent

Compounds with  Exceedance  Frequencies of 20% of More
       90
100
       Undiluted
3 Halogenated Methanes
2 Chlorinated Ethenes
4 Phthalates
9 Pesticides
  Benzene
  2,4-Dichlorophenol
  Phenanthrene
  1,2-Diphenylhydrazine
                       1:5 Dilution

                  3 Haloqenated Methanes
                  8 Pesticides
                    Tetrachloroethene
                    Bis(2-Ethylhexyl)
                     Phthalate
                    2,4-Dichlorophenol
                    Phenanthrene
 1:50 Dilution
4 Pesticides
  Dichloro-
   methane
  Phenanthrene
                                 799

-------
SUMMARY AND CONCLUSIONS

1.   Analytical methods have been developed that are capable of detecting
    priority pollutants in wastewaters and sludges at levels of 1  ug/1
    (10 ng/1 for pesticides).   Extensive use of blank and recovery samples
    is required to produce reliable quantitative data.

2.   The majority of plants in the survey had between 20 and 50 priority
    organics in their raw influents (at total concentrations under 1
    mg/l) with only 10 to 30 compounds in their final discharges.

3.   Only 15 compounds were found above 1 yg/1 (or 1 mg/kg) at least 80%
    of the time in raw wastewaters and at least 5055 of the time in final
    discharges and sludges.

4.   There was only a weak correspondence between the percent industrial
    flow to a plant and the number of priority organics found in the raw
    wastewater on a given day.

5.   Concentration levels of classes of priority organics varied widely
    between the plants surveyed.  Median percent removals of total benzenes,
    phenols, ethanes, ethenes,  PAH's, nitrogen-containing compounds,  and
    pesticides were all higher than 80/L

6.   The influent concentration of a compound or class of compound on any
    given day was found to be a poor predictor of effluent concentration.
    Removal of priority organics was not strongly associated with COD
    removal.

7.   The survey results could not statistically validate the hypotheses
    that chlorination produces more chlorinated priority organics or that
    tertiary treatment systems obtain higher removals of priority organics
    than secondary systems.

8.   With regard to proposed water quality criteria it appears that some
    22 compounds may be problematic in at least 20% of the systems surveyed.
    The most significant of these are dichloromethane, phenanthrene, and
    four pesticides.
                                     800

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 REFERENCES

 1.   Reichert, J.,  et al.  "Carcinogenic Substances Occurring in Water and
     Soil - XXVII:  Further Studies on the Elimination from Wastewater of
     Carcinogenic  Polycyclic Aromatic Hydrocarbons." Arch.Hyg.Bakt.,  155,
     18-40  (1971).

 2.   Schmidt,  T.  T.,  et al., "Input of Polychlorinated Biphenyls Into
     California Coastal Waters from Urban Sewage Outfalls."  Bulletin of
     Environmental  Contamination & Toxicology,  6^ No. 3,  235 (1971).

 3.   Lawrence, J.  and Tosine, H. M. "Adsorption of Polychlorinated Biphenyls
     from Aqueous  Solutions & Sewage." Environ. Sci. & Technol.  10, 38l (1976).

 4.   Chian, E.S.K.,  and DeWalle, F. B. "Presence of Toxic Substances  in
     Secondary Effluent and Their Attenuation in Receiving Waters."
     Environ.  Sci.  and Technol., submitted (1977).

 5.   Glaze, W. H.,  et al., "Analysis of New Chlorinated Organic Compounds
     in Municipal  Wastewaters after Terminal Chlorination." in "Identifica-
     tion and  Analysis of Organic Pollutants in Water." Ed., Keith, L.H.,
     Ann Arbor Science, Ann Arbor, Michigan (1976).

 6.   Consent Decree,  Natural Resources Defense  Council (NRDC) et al.  vs.
     Train, 8  ERG  2120 (1976).

 7.   DeWalle,  F.  B.,  Chian,  E.S.K., et al. "Presence of Priority Pollutants
     in Sewage and  Their Removal in Sewage Treatment Plants."  Draft  Report
     submitted to  USEPA on Grant No. R806l02,USEPA, Cincinnati,  Ohio
     (July 1981).

 8.   Feiler, H. "Fate of Priority Pollutants in Publicly Owned Treatment
     Works." Pilot  Study,  EPA-440/1-79-300.   Effluent Guidelines Division,
     Office of Water & Waste Management, USEPA, Washington, D.C. 20460.

 9.   Feiler, H. "Fate of Priority Pollutants in Publicly Owned Treatment
     Works." Interim Report, EPA 440/1-80-301,  Effluent Guidelines Division,
     Office of Water & Waste Management, USEPA, Washington, D.C. 20460.

10.   Westrick, J.J.,  and Cummins, M.D., "Collection of Automatic Composite
     Samples Without Atmospheric Exposure."  Jour. Water Poll. Control Fed.,
     51, 2948  (December 1979).

11.   Tigwell,  D.C.,  Schaeffer, D.J., and Landon, L. "Multichannel Positive
     Displacement  Teflon and Glass Sampler for  Trace Organics in Water."
     Anal. Chem.,  53, 1199 (July 1981).

12.   Environmental  Protection Agency.  Water Quality Criteria Documents;
     Availability.   Federal Register/Vol. 45, No.  231/Friday, Nov. 28, 1980.
     79318-79379.
                                    801

-------

-------
     CONTROL OF SPECIFIC ORGANIC AND METAL CONTAMINANTS
        BY MUNICIPAL WASTEWATER TREATMENT PROCESSES
Dolloff F. Bishop, Albert C. Petrasek, and Irwin J. Kugelman
                 Wastewater Research Division
         Municipal Environmental Research Laboratory
            U.S. Environmental Protection Agency
                   Cincinnati, Ohio 45268
        This paper has  been  reviewed  in accordance with
        the U.S.  Environmental  Protection  Agency's peer
        and administrative review  policies  and approved
        for presentation and  publication.
                   Prepared for Presentation at:
                8th United States/Japan Conference
                               on
                   Sewage Treatment Technology

                          October 1981
                        Cincinnati, Ohio
                              803

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CONTROL OF SPECIFIC ORGANIC AND METAL CONTAMINANTS BY MUNICIPAL WASTEWATER
TREATMENT PROCESSES

Dolloff F. Bishop, Albert C. Petrasek,  and Irwin J.  Kugelman
Wastewater Research Division
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio  45268
ABSTRACT

     The U.S. EPA's Municipal Environmental  Research  Laboratory is assess-
ing  the  removability of  toxic  substances  from municipal  wastewater  by
conventional wastewater  treatment  processes.   The studies feature pilot-
scale  primary/  secondary  treatment  of  the raw  wastewater  spiked  with
selected priority pollutants  (metals and  organics).   In the studies, the
treatment  plant performance  on  spiked  wastewater  is  compared to  the
performance  of  identical  treatment on the  unspiked  raw wastewater.   The
assessment employs costly  analyses  (GC/MS and  atomic absorption  methods)
for the selected toxic substances in the various process streams and sludges
of the conventional  treatment plant.  A biomonitoring approach to assess
health and  ecosystem effects is  also  being evaluated  to  supplement the
specific  toxic  substance  removal  data.    From  the  studies   to  date,
conventional treatment  is  generally  effective  in removing selected toxic
substances,  typically achieving  better  than 90%  removal  of organics and
from 60-80% removal of the metals.  A few of  the toxic substances, however,
pass  through into  the  treatment  plant's  final  effluent  in sufficient
concentrations which, based upon EPA recommended water quality standards,
may present a possible environmental hazard.

INTRODUCTION

     With  the  establishment of   the  Consent  Decree  list  of  priority
pollutants  (1), the  U.S.  Environmental  Protection  Agency  (EPA)  bej
-------
     •    The  highly  variable  and  low concentrations  of  the  specific
          compounds in the municipal wastewater.

     •    The inherent analytical variability associated with measurement
          of  parts  per  billion  concentrations  of  the   specific  toxic
          compounds in presence of substantial interfering background.

     •    Lack  of proper experimental  control systems  in the municipal
          treatment plant.

The  quantitative  uncertainty from these factors  can  be  minimized by the
addition of spiked amounts of representative specific organic  pollutants to
the  influent  of the municipal  treatment  system,  by providing sufficient
repetitive  measurements  of  the compounds  of interest,  and by  using  a
parallel identical treatment system on the same wastewater for experimental
control purposes.

     The  Municipal Environmental  Research  Laboratory of  the  EPA in co-
operation with  the EPA's Newtown Fish Toxicology  Station is  assessing Hie
removability, the fate and partitioning of specific toxics, and the impact
of  the  toxics during conventional municipal  wastewater  treatment  at the
EPA's new Test  and Evaluation Facility  in Cincinnati.  The basic approach
features the continuous spiking  of  individual toxics and groups of selected
toxic pollutants  into  the raw wastewater  from  the Cincinnati  Mill Creek
Sewage Treatment  Plant.   The spiked  wastewater enters pilot conventional
wastewater  treatment  systems in which  the fate  and  impact  of the added
toxics  are  repetitively  monitored as  they  pass through  the  treatment
processes.   Other identical  pilot systems,  as   the  controls,  treat the
unspiked Cincinnati raw wastewater.

     The ongoing studies include the evaluation of:

     •    The fate and removal of selected priority organic pollutants (4,
          5).

     •    The fate and removal of  indigenous metals (6).

     •    The impact and removal of selected  spiked metals (7, 8, 9, 10).

     •    The removal of  toxicity by the treatment  system as measured by the
          reduction in acute toxicity (11).

     •    The occurrence of chronic toxicity  to fathead minnow embryos in
          the treated effluents  (12).
     In  the  past,  the  municipal  wastewater  treatment  plant  has been
designed and operated  for removal of organic (BOD) loading  and occasionally
for nutrient control.  This research provides data for developing design and
operating criteria for municipal  wastewater treatment  to  remove  toxicity.
It provides a perspective on the  use of the municipal wastewater  treatment
plant as a cost-effective centralized alternative to industrial  pretreat-
ment for toxics removal.
                                   805

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EXPERIMENTAL SYSTEMS

     The  removal  of  specific  toxics  in  municipal wastewater  treatment
occurs through three chief mechanisms (13):

     •    Adsorption or precipitation  and  removal  with  the  solids in the
          treatment processes.

     •    Biodegradation

     •    Stripping of the volatile toxics during aeration

     Ideally, it is desirable to assess the removal of  toxics in full-scale
wastewater treatment plants.  However,  this approach is not practical with
spiking of  toxics.   In order to reduce  the variability and increase the
influent priority toxics concentration to  levels where reasonable numbers
of  repetitive  measurements produce  statistically reliable  results,  the
addition of  suitable  amounts of appropriate priority  toxics,  for periods
approaching  steady-state   (three  sludge  retention times),  can  be  very
expensive.   Full-scale spiking is  also  objectionable  because  of  toxic
discharges either in the plants  effluent,  in the  plant's  sludges or in the
air from the plant's  aeration processes.

Pilot Systems

     As  a practical  approach   for  the work to  date,  we  performed  the
assessment in small scale pilot systems  (Figure 1 and Table 1) for  the semi-
volatile or  non-volatile  toxics (organics  and metals) and in large pilot
systems (Figure 2 and Table 1)  with  representative side water depths for
volatile  organics.   The Cincinnati Millcreek Plant's raw wastewater was
used for the studies.  In the work, a total of four identical small pilot
systems (Figure 1), and two identical large pilot systems (Figure 2) were
used.  The operation at steady  flow of these municipal  treatment systems
was performed with continuous  24-hour operator supervision.  The operating
conditions for the various  studies and the various spiked mixtures  added to
experimental  treatment    trains are  described  later in  the subsequent
discussions  of the individual  studies.

Cincinnati Wastewater

     The raw wastewater  entering the Cincinnati Mill Creek Sewage Treatment
Plant by U.S. standards  is a strong municipal wastewater  (typical  COD ~ 650
mg/1) from a collection system with significant industrial contributions.
The substrate  concentrations in the wastewater  compared to those in the
Cincinnati  municipal  water  supply  (Table 2)  reveals  the  substantial
increases in substrate  caused by  the municipal/industrial use in Cincin-
nati.  These substrate increases compared to substrate  increases in typical
U.S. domestic wastewater indicate  a strong industrial  contribution.  Thus,
the raw wastewater, by itself,  is  well  suited for assessing  the use of the
central municipal plant for control of toxics.
                                    806

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     HEAD TANK
                         TO PARALLEL SYSTEM
                                                  I SPIKE SOLUTION
00
o
  RAW WASTEWATER PUMP

    AT MILL CREEK 8TP
WASTE ACTIVATED


    SLUDGE
                          Figure  1.   Pilot System  for Metals  and Semi-Volatile  Organic Studies.

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                  Table 1.   Pilot System Specifications.
                                   Metal and                Volatile
     Pilot System               Semi-Volatiles^a'            Organics

Design flow, L/d                   7570                     190,700

Aerated grit chambers

     diameter, m                      0.55
     side water depth, m              0.5
     air rate, L/S                    0.3
     residence time, min.            20

Primary clarifiers

     diameter, m                      0.91                    2.94
     side water depth, m              1.5                     3.66
     surface area, m2                                         6.82
     overflow rate, m3/m2/d          12.4                    24.2

Aeration basins

     width, m                         0.61                    3.05
     length, m                        3.05                    5.36
     sidewater depth, m               1.37                    3.66
     residence time, hr               7.5                     7.5

Secondary clarifiers

     diameter, m                      0.91                    3.63
     sidewater depth, m               1.5                     3.66
     surface area, m2                                        10.36
     overflow rate, m3/m2/d          12.4                    15.9
a System include a sewer simulator (steel pipe) 25.6 meters long, 102 mm
  in diameter, with 3.15 L/S recycle pump and a 380 L sump.
                                    808

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                                                                           CONTROL TRAIN
00
o
IO
                                                                                                          SECONDARY EFFLUENT
                                                                                                          SECONDARY EFFLUENT
                                         Figure 2.   System for  Volatile  Organics Study.

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          Table 2.  Increase in Substrate Concentration Dye  to
                    Municipal/Industrial Use in Cincinnati.
Substrate
Ag(a)
As
Ca
Cd<«>
Cr
Cu
Fe
Hg(a)
Mg
Mn
Ni
Pb
Zn
Cl
F
S04
Si02
TDS
Influent Wastewater
N
37
37
39
37
37
37
37
37
39
37
37
37
37
39
39
39
39
39
Standard Deviation
13.0
19.6
26.0
14.7
0.47
0.38
2.58
1.0
4.9
0.3
0.75
0.43
0.65
76.0
0.2
63.0
28.9
526
Arith.
Mean
mg/1
8.0
20.6
86.0
20.9
0.63
0.80
4.29
< 2.0
17.6
0.65
0.45
0.88
1.24
269
0.6
288
45.1
1537
Drinking
Water
mg/1
o.oo(b)
5(b)
45
0.000(b)
0 . 002 ^b)
-
0 . 30 ^c '
O.l(b)
9.2(c)
0.00(c)
-
o.ooeCb)
-
28
0.3(c)
83
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 Analytical  Procedures

      During the studies, repetitive sets of appropriate composite (usually
 24-hr)  samples of the  process  flows  and  sludges  were  simultaneously
 collected  for  both the control and spiked treatment  systems.   The  sample
 sets  were  analyzed at  either the EPA  laboratory operated  by the Waste
 Identification and Analysis Section of the Municipal Environmental Research
 Laboratory  or  by Battelle-Columbus  Laboratories.   The  EPA  Laboratory
 provided all conventional analyses including metals using EPA methods  (14)
 or Standard Methods (15).  The  specific organic analyses were shared  by the
 EPA and Battelle  Laboratories.   In the  organic analyses,  the  Laboratories
 used  modifications of the Agency's standard procedures for wastewater  (16)
 and interim procedures  (17, 18) for sludges.   The complexities involved in
 the sample work-up procedures and in  GC/MS methodology for the analysis of
 the organic priority pollutants in municipal wastewaters have been reported
 by Bishop  (19).

      Additionally, appropriate grab samples were  collected at 4-hour  inter-
 vals  for routine process control and included mixed liquor and return  slud^p
 respiration rates,  effluent  turbidities,  settled  sludge  volumes  (30-
 minute), pH, and  alkalinity.

 Quality Control Approach

      In the earlier phases of the  work,  the EPA Laboratory employed limited
 QC procedures  in  its automated conventional analyses.   These  consisted of
 the required standard curves,  check standards  (5-10%),  and  blanks.  Large
 numbers of repetitive samples provided the statistical support to the data.
 As the studies progressed, the Laboratory participated  in  the development
 of the Agency's prototype  Sample File  Control (SFC) system for data manage-
 ment  and documentation  of quality control.  The  QC results  (precision and
 accuracy)   for the conventional  analyses  are  included in  the  evaluation
 report (20) of the prototype  SFC  system.

      Due to the complexities associated with  the  sample work-up procedures
 for specific organics  as  well as the variability in results reported  by
 other investigators, a comprehensive quality control protocol was employed
 in the studies  for the organic priority  pollutant analyses.    The  sample
 locations were evaluated  for matrix  effects  based on conventional water
 quality parameters such as COD, TOC,  NH^-N, etc.   The  influent, the sewer
 simulator effluent, and the  aerated  grit  chamber effluent  all  had  essen-
 tially identical matrix characteristics  for the purposes of the QC program.
 The four additional matrices identified were the  primary  clarifier  efflu-
 ent,  the  activated sludge effluent,  the  primary  sludge,  and  the  return
 activated sludge.

     With each  organic  sampling  set, appropriate samples were collected
 from the  control treatment system  for  each of  the  five matrices identified.
 Two    replicate samples were run as duplicate background blanks.  Two other
 replicate samples received a  quality  control  spike containing  all of  the
 compounds being  studied.    This   scheme provided duplicates  on both   the
background blanks  and  the  quality control  spiked  samples for precision  and

                                   811

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accuracy determinations in all matrices.   All quality control samples were
then subjected to the complete sample work-up and analytical protocol. The
QC results are or will be summarized in  the individual reports (4, 5) on the
organic studies.

ORGANICS REMOVAL

Semi-Volatile Organics Study

Pilot Plant Operations

     Routine  sampling and data acquisition for the semi-volatile organics
studies commenced on  October  1,  1979,  and the project  was terminated on
August 8, 1980.  Table 3 presents a summary of the process operation for the
312-day  study period.   The influent  flows  to both  systems  had  a mean
variation of  only 6.1 percent; the means being  0.083  1/s and 0.088  1/s for
the control and spiked systems, respectively.   The return activated  sludge
(RAS) flows averaged 0.035 1/s for the  control  train  and 0.038 1/s  for the
spiked train,  or about 42 percent of the influent flows for each system.  The
mixed liquor  suspended solids and  RAS concentrations  were approximately
1900 mg/1 and 6400 mg/1, respectively.

     The systems were operated at a nominal SRT  of 7 days, which resulted in
a F/M of 0.6 kg COD  applied  per day per kg MLSS, or a F/M of 0.18 on a TOC
basis.   The  average normalized  oxygen uptake  rates  (OUR) for  the mixed
liquors and RAS's  are shown in Table 3.   A comparison  of  the operating data
between  the control and  spiked  treatment sequences  indicates  that both
systems were  operated in essentially the  same manner.

     Median water quality data for both treatment sequences are  summarized
in Table 4, and these data indicate  that  the pilot scale  systems were pro-
viding good treatment.  Total suspended solids,  COD, and TOC reductions were
95,  89,  and  90  percent, respectively.   The  activated sludge  processes
produced significant ammonia nitrogen reductions  even though  they were not
operated to consistently nitrify.

     Twenty-two  semi-volatile organics  spiked into the  raw wastewater
(Table 5) were selected from those organics found in the  raw wastewaters of
the first 20 of  the municipal wastewater treatment plants from the 40 Cities
Survey (2).   A  nominal  spiking concentration of 50 /ig/1 for  each  single
component compound  was selected as representative  of  the concentrations
found in the Survey.  Since Arochlor 1254 and toxaphene were multicomponent
mixtures, a nominal 150 /tg/1 of each mixture was selected to improve their
quantitation by GC/MS.

     The purity of each compound was verified by gas chromatography prior to
preparation of the spiking solution.  The selected semi-volatile organics
were dissolved  in toluene  to  provide a spiking solution containing 0.143
percent by  weight of each  of the  single component compounds  and 0.429
percent  for  the  toxaphene  and Arochlor 1254.    As  a quality  control
highlight,  the recoveries  of  spikes   of the  individual  semi-volatile
organics into  four system matrices are presented in Table 5.  The recoveries

                                   812

-------
     Table 3.  Process Operation During  Semi-Volatile  Organic  Study;
                October 1, 1979 through August 8, 1980.
Parameter
Influent Flow, Q, 1/s (gpm)
RAS(a> Flow, Qr; 1/s (gpm)
Waste Activated Sludge, 1/d (gpd)
Waste Primary Sludge, 1/d (gpd)
MLSS, mg/1
RAS concentration, mg/1
Normalized ML-OUR,
-------
                    Table 4.   Plant Performance During Semi-Volatile Organics Study
                              October 1,  1979 through August 8, 1980
oo
Parameter


TSS
COD
TOC
T-P
NH3-N
N02 and N03~N
Alkalinity (as CaCC^)


TSS
COD
TOC
T-P
NH3-N
N02 and N03~N
Alkalinity (as CaC03)
Influent
(mg/1)


490
650
180
8.3
20
.1
—


430
640
180
8.1
20
.1
-
Sewer
Simulator
Effluent
(mg/1)


505
660
194
8.0
19
.1
—


505
640
185
7.9
17.3
.1
-
Grit Primary
Chamber Clarifier
Effluent Effluent
(mg/1) (mg/1)

Control Sequence
408
700
198
8.7
19
.1
290
.
Spiked Sequence •
490
670
190
8.6
17.3
.1
290


265
390
122
5.6
19
.1
300


257
365
114
5.6
18.3
.1
290
Activated
Sludge
Effluent
(mg/1)


26
74
18
2.9
1.5
3.6
188


26
76
19
2.7
.9
5.2
170
Overall
Removal
(%)


95
89
90
65
93
-
-


94
88
90
67
96
-
-

-------
        Table 5.  Mean Recovery Values for Various Sample Locations
                  and Classes of Compounds.

PESTICIDES/PCB's
Arochlor 1254
Heptachlor
Lindane
Toxaphene
Mean Recovery
PHENOLS
2 ,4 -dimethyl phenol
Phenol
Pentachlorophenol
Mean Recovery
PHTHALATES
Bis(2-ethylhexyl)phthalate
Butylbenzylphthalate
Diethylphthalate
Dime thy Iphthalate
Di-n-butylphthalate
Di-n-octylphthalate
Mean Recovery
Reported^3)
ribn

42
49
64
83
60

72
54
84
70

66
49
65
66
58
88
65
Average
Inf.

54
71
60
60
61

60
72
74
69

86
70
77
73
74
65
74
Recovery
Sample
Act.
Sludge
Eff.

74
98
71
64
77

54
68
120
81

76
58
70
62
70
68
67
 for
Sets
Pri.
Sludge

61
28
32
66
47

44
28
49
74

34
25
69
56
57
31
45
Eight
Return
Act.
Sludge

53
68
72
74
67

17
31
79
42

50
62
31
15
68
62
48
POLYNUCLEAR AROMATIC HYDROCARBONS
Acenaphthene
Anthracene
Benz (a )anthracene
Chrysene
Fluor an thene
Fluorene
Naphthalene
Phenanthrene
Pyrene
Mean Recovery
78
79
51
77
63
88
89
79
68
75
79
64
59
48
62
79
66
71
60
65
77
71
55
71
58
81
84
65
61
69
71
45
48
63
64
75
25
67
62
58
58
60
35
56
58
59
41
60
52
53
a Industrial and municipal wastewaters.
  Recovery expressed as percent.
                                    815

-------
in the wastewater matrices are comparable to those reported by Kleopfer (21)
as representative of reasonable analytical performance.

     The Cincinnati raw wastewater with a high  average  COD of 650 provides
a stronger background of extractable interferences than typical municipal
wastewaters.  This wastewater produced sludges,  especially primary sludges,
which were intermittently very difficult to handle, especially during the
extraction process.   As  expected the recoveries in the sludge matrices were
generally lower than those encountered in the wastewater matrices.

Semi-Volatile Organics Removal

     The results of the  analyses for the organic priority pollutants in the
control  and  spiked  systems are presented in Tables 6 and 7.   The  data
reported  are the  arithmetic means  for  all  eight sample  sets  and  all
concentrations  are  in micrograms  per  liter.   Additionally,  all concen-
trations  used  for  computing  the mean concentration   were  corrected  for
recovery factors determined  from the quality control spikes  for each sample
set.

     Most of the selected organics in the  unspiked raw wastewater were found
at or near the detection limits (1 to 10 /ig/1) of the  analytical methods.
Phenol,  several phthalates  and  napthalene were  observed  in relatively
substantial concentrations in the unspiked raw wastewater.  Spiking,  sub-
stantially increasing the concentrations  of the organics in the wastewater,
permitted evaluation of the removals across the plant.

     In general, the concentrations of the spiked organic priority pollu-
tants found in the effluent of the primary clarifier (Table 7) were slightly
higher than the  influent concentrations.  Even a cursory examination of the
data for the primary sludge  samples  indicates that considerable removal of
these materials  did occur  in the  primary clarifier.    The inconsistency
between the influent and primary effluent data can be  understood when one
realizes that the standard deviations for both the influent  and the primary
effluent samples typically ranged from 50 to 100 percent, which is normal
for GC/MS quantitation at low concentrations.

     A comparison of the influent and activated sludge effluent data of the
spiked  system  indicated  that  the  treatment   sequences  were  generally
effective in  reducing the concentrations of  the organic compounds in the
wastewater streams.   The spiked system typically  produced  a more than 97
percent reduction in the concentrations of the compounds being  spiked. Most
of the residual concentrations of  the  chemicals were  below the detection
limits  in  the  activated sludge  effluent.   Lindane,   bis-(2-ethylhexyl)-
phthalate, di-n-octylphthalate pentachlorophenol, and  phenol were found  in
analytically  significant concentrations  (< 4.8 to 25.8 ;ig/l) in the
secondary effluent.

     Substantial concentration increases occurred in both the primary and
return activated sludges.   Typically a two order of magnitude increase in
concentration, based on  the influent values, occurred in the  primary sludge
samples.  Concentration  increases observed in the return sludge ranged from
0.5 to 1.5 orders of magnitude depending on the specific compound.
                                   816

-------
                     Table 6.   Mean Concentrations of Semi-Volatile Organics in
                               the Control Treatment System.
CO
Influent
(yg/D
PESTICIDES/PCS' s
Arochlor 1254
Heptachlor
Lindane
Toxaphene
PHENOLS -
2,4-dimethylphenol
Phenol
Pentachlorophenol
PHTHALATES
Bis (2-ethylhexyl )phthalate
Butylbenzylphthalate
Diethylphthalate
Dimethylphthalate
Di-n-butylphthalate
Di-n-octylphthalate
POLYNUCLEAR AROMATIC HYDROCARBONS
Acenaphthene
Anthracene
Benz(a)anthracene
Chrysene
Fluoranthene
Fluorene
Napththalene
Phenanthrene
Pyrene

< 2.9
< 1.0
< 2.0
< 2.9

< 17.5
111.0
8.9

63.1
< 7.2
< 7.1
< 3.2
16.0
< 6.3

< 1.8
< 5.4
< 0.8
< 5.1
< 2.1
< 2.4
< 95.4
8.8
< 1.8
Activated
Primary Sludge
Effluent Effluent
(yg/l) (yg/l)

< 2.9
< 1.0
< 1.0
< 2.9

< 13.6
46.0
< 5.7

30.5
< 5.6
< 12.3
< 17.5
< 11.8
< 3.6

< 2.9
< 2.7
< 0.8
< 2.1
< 1.3
< 2.1
< 74.7
< 4.5
< 1.3

< 2.6
< 1.0
< 1.0
< 2.6

< 0.9
< 8.2
< 1.8

6.4
< 4.4
< 1.0
< 0.7
< 2.4
< 2.2

< 1.0
< 1.0
< 0.8
< 0.8
< 0.6
< 0.7
< 1.0
< 0.9
< 0.7
Primary
Sludge
( yg/D

< 403.0
< 52.9
< 146.0
< 1,063.0

< 57.9
983.0
853.0

6,384.0
2,841.0
< 75.8
< 13.6
1,255.0
< 770.0

< 121.0
< 560.0
< 292.0
431.0
< 488.0
< 175.0
3,583.0
< 646.0
< 844.0
Activated
Sludge
( yg/D

< 200.0
< 58.7
< 88.2
< 97.9

< 197.0
< 35.5
< 52.4

928.0
< 294.0
< 180.0
< 12.6
< 190.0
< 13.9

< 53.0
< 89.6
< 59.1
< 132.0
< 84.1
< 46.8
< 37.5
< 69.0
< 110.0

-------
                      Table 7.   Mean Concentrations of Semi-Volatile Organics  in

                                the Spiked Treatment System.
oo
i—'
oo
Influent
(yg/D
PESTICIDES/PCB's
Arochlor 1254
Heptachlor
Lindane
Toxaphene
PHENOLS
2,4-dimethylphenol
Phenol
Pentachlorophenol
PHTHALATES
Bis(2-ethylhexyl)phthalate
Butylbenzylphthalate
Diethylphthalate
Dimethylphthalate
Di-n-butylphthalate
Di-n-octylphthalate
POLYNUCLEAR AROMATIC HYDROCARBONS
Acenaphthene
Anthracene
Benz ( a ) anthracene
Chrysene
Fluoranthene
Fluorene
Napththalene
Phenanthrene
Pyrene

< 33.5
31.7
45.5
< 47.4

< 82.1
261.3
7.6

51.7
33.5
46.4
< 41.8
43.8
28.2

39.8
34.8
23.8
38.9
30.6
37.9
76.7
40.4
30.4
Primary
Effluent
( yg/D

< 114.0
< 28.5
< 41.8
< 87.5

60.9
> 196.2
13.0

52.4
37.5
57.7
< 37.2
54.4
< 34.4

53.6
33.9
24.9
36.6
39.9
51.6
242.5
44.3
39.1
Activated
Sludge
Effluent
( yg/D

< 2.9
< 2.3
25.8
< 2.9

< 0.9
< 13.5
< 6.3

11.3
< 1.3
< 1.2
< 0.8
< 2.7
< 4.8

<1.2
<0.9
<0.6
< 1. 2
< 1.9
<0.7
<0.7
< 1.1
<2.0
Primary
Sludge
( yg/D

13,500.4
< 2,152.0
< 1,130.3
< 8,213.1

< 20.7
< 2,348.3
< 410.7

< 6,713.0
< 8,160.0
< 710.3
< 37.2
3,482.4
< 5,278.0

3,354.0
4,809.8
< 3,241.5
5,982
5,281.0
< 3,921.0
< 3,463.0
< 4,931.0
< 6,640.0
Return
Activated
Sludge
( yg/D

5,403.0
526.7
< 173.7
<1,655.4

< 20.0
< 92.1
< 20.0

978.0
< 123.3
< 196.7
< 39.5
< 233.8
< 580.7

< 68.3
< 84.6
< 208.9
< 240.9
< 196.0
< 57.9
< 18.3
< 28.4
< 104.2

-------
     Mass distributions (Table 8) were computed for each compound based on
 the  mean concentrations  observed in  the influent,  secondary effluent,
 primary  sludge, and return activated sludge, and the operating parameters
 presented in Table 3.  Since most of the compounds studied are biodegradable
 to some  extent, the probability of accounting for 100  percent  of any given
 chemical was expected to be low;  additionally, good accounting
 of the chemicals in  the distribution balances was not anticipated due to the
 inherent variability in the GC/MS data.   The results of the  distribution
 calculations  for the  spiked  system,  in general,  are much  better than
 anticipated; the  total percentages of the different compounds which were
 accounted for are reasonable.

     The pesticides and PCB's  partitioned approximately equally between the
 primary  sludge and  the waste  activated sludge.   A substantial portion of
 lindane, 55 percent, was  found in the activated sludge effluent. The three
 phenols  studied  were not  found  to concentrate  in either of the  sludge
 streams.  These  data indicate  that two of the phenols studied are relatively
 biodegradable.  Pentachlorophenol substantially passed through the treat-
ment plant.

     On a mass flow basis  the  phthalates were unevenly distributed between
 the two  sludge  streams; more  of the  compounds were  found  in the primary
 sludge.  The results indicate that diethyl and dimethylphthalate are more
 biodegradable than the other compounds studied  in that  class.   Since these
 two compounds have the simplest structure, this  finding is not surprising.

     The PAH's are  the least  polar of  all  the compounds.  One would,
 therefore, assume their preferential adsorption  to the solids, which are
 removed  in primary  treatment.  As a class, the PAH's  concentrated  in the
 primary  sludge to the greatest degree.  In contrast,  only low amounts of
 the PAH's were found in the WAS  samples.

     This research did demonstrate that a typical POTW, with the processes
 studied,  significantly reduced   the  concentrations  of   the   22  organic
 priority  pollutants;  however, certain compounds, most notably lindane,
bis(2-ethylhexyl)phthalate, phenol, and  di-n-octylphthalate  were present
 in the activated sludge effluent  in relatively significant concentrations.
The impact of these  low-level residuals on the aquatic environment would be
a function of many site-specific  factors, such as ambient water quality and
dilution flows.   However,  based on the  potential  for bioaccumulation (22),
 toxicity data reported in the literature  (23),  suggested  water  quality
criteria (24), and the presence of the materials  in  the secondary effluent,
one can only conclude that the POTW is not a totally effective system for
controlling  the  entry of some  compounds into  the environment via  the
wastewater discharge.   Furthermore,  although  some compounds  were  bio-
degraded, many of the chemicals studied were present in  the sludges in very
high concentrations.  The  fate of these  materials in the  solids handling
processes is  not known at this  time,  and  additional  research must  be
conducted to provide answers to this  pressing question.
                                   819

-------
                   Table 8.   Distribution of  Semi-Volatile Organics in the Spiked

                              Treatment  System.
oo
ro
o
Influent
(gm/day)
PESTICIDES/PCB ' s
Arochlor 1254
Heptachlor
Lindane
Toxaphene
PHENOLS
2 ,4-dimethylphenol
Phenol
Pentachlorophenol
PHTHALATES
Bis(2-ethylhexyl)phthalate
Butylbenzylphthalate
Diethylphthalate
Dimethylphthalate
Di-n-butylphthalate
Di-n-octylphthalate
POLYNUCLEAR AROMATIC HYDROCARBONS
Acenaphthene
Anthracene
Benz(a)anthracene
Chrysene
Fluoranthene
Fluorene
Napththalene
Phenanthrene
Pyrene

0.977
0.240
0.345
0.977

0.622
1.979
0.058

0.392
0.254
0.352
0.317
0.332
0.214

0.302
0.264
0.180
0.295
0.232
0.287
0.581
0.306
0.230
Percent in
Primary
Sludge

51
33
12
31

0
4.4
26

63
119
7
0.3
39
91

41
67
67
75
84
51
22
59
107
Percent in
Waste
Activated
Sludge

60
35
8
27

0.5
0.8
c

39
7
9
2
11
43

4
5
18
13
13
3
0.5
1
7
Percent in
Final
Effluent

2
7
55
2

1.1
5
81

21
4
3
2
6
17

3
3
f\
3
6
2
1
3
6
Total Mass
Recovered
(percent)

113
75
75
60

1.6
10.2
112

123
130
19
4.3
56
151

48
75
87
91
103
56
23.5
63
120

-------
Volatile Organic Study

Pilot Plant Operations

     The study on the volatile organics  is ongoing.  The results presented
represents a preliminary assessment of the available data.  Quality control
refinement has not been applied to the data.  The operations of the two pilot
systems (Figure 2)  for the  volatile studies  are summarized in Table 9. The
two systems  exhibited stable and straight-forward  operation.   The water
quality performance  for the  treatment sequences  (Table  10)  indicated the
pilot systems provided good treatment.  The operations data and performance
in both control and  spiked  systems indicate  essentially the same operation
for both systems.

     The  16 volatile  organics  in  the  initial  phase of  the work  were
nominally spiked into the experimental treatment system at 50 jig/1.  Higher
spiking  concentrations  will  also  be  employed.    Organic   analysis,  in
addition to the usual wastewater and sludge process streams, will include
gas phase analyses of the air streams from the aeration basin.

Volatile Organics Removal

     The selected volatile organics (Table 11) are usually present in the
Cincinnati raw wastewater in analytically measurable quantities (0.2 ug/l).
The spiking substantially increased the concentrations of the organics to
improve the evaluation of the removability by the treatment plant.

     The  initial evaluation  of  the  data  (Table  12) reveals  excellent
removals  for  most  of the  purgeable  organics with  90 percent  or better
removals.   Two organics,  1,1,2-Trichloroethane  and Dibromochloromethane
exhibited relatively  low  removals of approximately 70 percent  with  sub-
stantial residuals in the secondary effluent.  Toluene,  Ethylbenzene, the
combination  of  tetrachloroethylene  and  tetrachloroethane,  and  1,2-Di-
chloropropane,  while exhibiting  nearly 90  percent  removals or  better,
passed  through the  treatment  system  into   the  secondary effluent  with
concentrations greater than 2 Jig/1.   The ongoing work will provide further
evaluation of the fate and distribution of these organics.

METALS REMOVAL.AND IMPACT

     The  metals studies  involved two  separate  operational  periods;  an
evaluation of  the  distribution  and  removal of indigenous metals  in the
Cincinnati raw  wastewater by  the control treatment system (6) during the
semi-volatile  organics  studies?  and subsequent  studies  in 'which  four
specific metals~Cd  (7), Pb (8), Hg  (9), and Cr  (10)—were spiked into the
small pilot systems (Figure 1) in a sequence of increasing concentrations of
the individual  metal.   The  studies  on  the individually  spiked  metals
included an unspiked control  system in order to compare the impacts of the
increasing metal concentrations with the conventional plant operation and
performance.
                                    821

-------
             Table 9.  Operations Summary, Volatile Priority
                       Pollutant Sequence; January-June  1981

Influent Flow, Q (gpm)
Flow, Qr (gpm)
Waste AS, Qw (gpd)
Primary Sludge, Qp (gpd)
OUR3- ML (mg-hr/1)
OUR - RAS (mg-hr/1)
Normalized ML OUR
Normalized RAS OUR
MLSS (mg/1)
RAS (mg/1)
ML Cent. Vol. (%)
RASbCent. Vol. (%)
SRT (days)
SVI (ml/gm)
System
Control
38.4
8.5
1,472
897.0
37.8
96.6
0.015
0.006
2,694
12,954
3.4
17.3
4.6
114.0
Spiked
34.7
8.4
1,471
1,219
47.8
87.2
0.016
0.005
2,940
13,326
3.7
15.8
5.1
111.0
a = Oxygen Uptake Rate (OUR).
b = Return Activated Sludge (RAS).
                                    822

-------
                   TABLE  10.  Performance of Volatile Priority  Pollutant
                              Treatment Sequences; January-June 1981
Parameter
TSS
COD
Total-P
ro TKN
oo
Organic N
NHy-N
N02 & N03-N
Total-N
Turbidity (NTU)
UCOD(a)
Influent
(mg/1)
447.0
557.0
9.3
43.5
20.4
23.1
0.2
43.7
-
683.0
Primary
Effluent
(mg/1)
214.0
317.0
6.0
36.7
14.2
22.5
0.2
36.9
-
421.0
Removal by
Primary
Clarifier
52.0
45.0
35.0
16.0
30.0
3.0
-
16.0
-
38.0
Activated Sludge Eff.
(mg/1)
Control
30.0
91.0
3.1
19.4
5.7
13.2
6.4
25.8
12.0
152.0
Spike
23.0
87.0
2.8
18.4
5.2
13.2
6.3
24.7
10.0
148.0
Overall Removal
(percent)
Control
93.0
84.0
67.0
55.0
72.0
43.0
-
41.0

78.0
Spike
95.0
85.0
70.0
58.0
75.0
43.0
-
43.0

78.0
a UCOD = Ultimate Combined Oxygen Demand = COD +4.6 (NK^-N).

-------
                  Table  11.  Mean Concentrations^a' Observed  in Eight  Sample  Sets:
                            January 12 through July 28, 1981.
Control System
Inf.
Methylene Chloride
1 , 1-Dichloroethene
Chloroform
Carbon Tetrachloride
1 ,2-Dichloropropane
Trichloroethylene
oo 1,1,2-Trichloroe thane
ISJ
*" Dibromochloromethane
Benzene
1 ,1 ,1-Trichloroe thane
Bromodichlorome thane
Chlorobenzene
Tetrachloroe thy lene
and
Tetrachloroe thane
Toluene
Ethylbenzene
47
0
11
3
<0
4
1
0
0
83
< 0
57
19
114
19
.1
.3
.3
.6
.2
.3
.5
.7
.5
.0
.2
.0
.3
.0
.5
Pri.
Eff.
33.2
< 0.2
7.4
4.0
< 0.2
1.5
1.0
0.3
0.8
32.7
< 0.2
36.5
10.0
98.6
27.3
Activ.
Sludge
Eff.
5.8
< 0.2
0.5
< 0.2
< 0.2
< 0.2
1.2
< 0.2
< 0.2
1.7
< 0.2
< 0.2
< 0.2
18.1
< 0.2
Return
Activ.
Sludge
2.0
< 1.0
7.2
< 1.0
1.8
< 1.0
16.6
1.9
< 1.0
2.4
< 1.0
1.8
6.8
122.8
26.0
Pri.
Sludge
32.3
< 1.0
3.5
< 1.0
< 1.0
9.2
2.9
< 1.0
14.4
41.9
< 1.0
702.5
161.6
591.3
522.6

Inf.
84.3
43.5
45.8
20.3
55.6
36.5
62.0
42.0
35.0
254.3
19.7
169.3
71.7
162.7
41.8

Pri.
Eff.
76.0
9.6
37.2
6.7
52.7
32.7
50.8
31.2
16.5
63.2
19.8
126.3
74.2
158.6
39.7
Spiked
Activ.
Sludge
Eff.
1.0
< 0.2
1.4
0.3
2.3
1.2
22.5
12.1
0.2
1.5
0.9
0.3
3.8
13.7
4.9
System
Return
Activ.
Sludge
1.2
< 1.0
3.6
< 1.0
< 1.0
< 1.0
17.4
1.3
< 1.0
< 1.0
< 1.0
1.5
5.6
2.9
3.6

Pri.
Sludge
111.4
0.7
9.7
0.6
63.2
263.3
18.9
2.9
224.3
40.3
0.2
736.7
570.9
627.9
570.7
a All concentrations in  Ug/1.

-------
          Table  12.   Distribution of Volatile Priority Pollutants
                     In the Spiked Treatment Sequence

Methylene Chloride
1 , 1-Dichloroethene
Chloroform
Carbon Tetrachloride
1 ,2-Dichloropropane
Trichloroethylene
1,1, 2-Trichloroethane
Dibromochlorome thane
Benzene
1,1, 1-Trichloroethane
Bromodichlorome thane
Chlorobenzene
Tetrachloroethylene
and Tetrachloroethane
Toluene
Ethylbenzene
a = Removals based on mass
Percent
Found in
Primary
Sludge
3.2
0.04
0.52
0.08
2.76
17.54
0.74
0.16
15.63
0.39
0.02
10.62
19.42
9.42
33.29
balance.
Removal
by Primary
Clarifier
(percent)
9.9
77.9
18.7
66.9
5.2
10.4
8.1
25.7
52.9
-
NR
25.4
NR
2.5
5.1

Percent
Found in
Waste Act.
Sludge
0.04
0.07
0.23
0.16
0.06
0.09
0.83
0.09
0.09
0.01
0.16
0.03
0.23
0.06
0.25

•a
Removal by
Treatment
Sequence
98.9
> 99.5
99.4
98.7
96.1
97.0
65.6
72.7
99.4
99.4
95.7
99.8
95.0
97.1
88.9

NR = Not removed.
                                    825

-------
Distribution and Removal of Metals

     The  pilot  plant  operating  conditions  (Table  3)  and  overall  plant
performance (Table 4, control system) are the same as  those in semi-volatile
organics study.   The pilot system exhibited  very stable operations and very
satisfactory plant performance with  the  background metals  in the influent
wastewater.

     The metals  concentrations  in the Cincinnati raw wastewater  (Table 2) is
typical of  U.S.  cities with substantial industrial  contributions.   Com-
parison to  the  mean influent metals in  Washington,  B.C.  (25)  and Dallas,
Texas  (26)  revealed  significantly higher metals concentrations.   In many
cases  (Zn,  Pb, Mn,  Cu,  and  Cr),  the concentration  difference exceeded one
order of magnitude. The Cincinnati metals concentrations, however, are all
less than the maximums reported for twenty municipal treatment plants (2).

     The metals  concentrations  for plant process streams and  the primary and
secondary sludges, except for  the soluble Cu and Mg  and Hg  (concentration
below or near the  detection limit), were presented as  log normal probability
distributions.   Summary highlights of  the  data analyses  for  this metals
overview work are presented in Tables 13, 14, and 15.

     Table 13 summarizes  the metals removals, computed from the mean concen-
trations,  for the primary clarifiers,  activated  sludge process,  and  the
overall system.   As one would predict, there was no  significant removal of
either Ca or Mg.  The ambient Hg concentrations were too low to permit the
quantitation of  removal in a  proper manner.  The total  removals for the
remainder of the metals range from 19 percent for As to 80 percent for Cu, and
are representative of typical plant removals.

     Metals concentration factors are presented for  the primary and return
activated sludges  in Table  14.   The concentration factor  was  computed by
dividing the mean sludge  concentration  (mg/1 basis) by  the mean influent
concentration.

     Mass balance  calculations were performed using the mean contaminant
concentrations and the  pilot plant operating data presented  in Table 4.  The
results of the mass balances  are  summarized  in Table  15.  For the  13 cations
reported the average closure on  the  mass balance was 94.2  percent for the
total system, and 94.0  percent  on the primary clarifier.  Cd and Fe were the
two metals with the worst closures.   Examination of  the Cd data  indicates
that the concentration in the waste  activated sludge  is probably  low, while
the problem with iron appears to be low concentrations in both sludges.

Metals Impact

     Soluble salts of  the metals Cd,  Pb, Hg, and  Cr(+6) were added to the
small pilot  systems  (Figure  1)  and  the spiking concentration periodically
increased to ultimately stress  the treatment  process to failure.   A parallel
control system without  the spike was operated identically during  each metal
study.    The operating conditions  at  each  metal  concentration level were
maintained  relatively  constant,  but were varied during  the course of the

                                    826

-------
          Table  13.  Metals  Removal  in Control  Treatment  Systems.
Metal
A 
Ag
As
Ca
Cd
Cr
Cu
Fe
Hg(a, b)
Mg
Mn
Ni
Pb
Zn
Influent
(mg/1)
8.0
20.6
86.0
20.9
0.63
0.80
4.29
2.0
17.6
0.65
0.45
0.88
1.24
Removal
Pri. by
Eff. Pri. Clar.
(mg/1) (percent)
9.0
16.0
81.0
17.0
0.51
0.57
2.44
2.0
18.0
0.55
0.27
0.58
1.28
0.0
22.3
5.8
18.7
19.0
28.8
43.1
-
0.0
15.4
40.0
34.1
0.0
Act
Sludge
Eff.
(mg/1)
5.0
16.7
81.0
7.9
0.34
0.16
1.01
2.0
17.9
0.40
0.18
0.11
0.46
Removal
by
Act. Sludge
(percent)
44.0
0.0
0.0
53.5
33.3
71.9
58.6
-
0.0
27.3
33.3
81.0
64.1
Total
Removal
(percent)
37.5
18.9
5.8
62.2
46.0
80.0
76.5
-
0.0
38.5
60.0
87.5
62.9
a Micrograms/liter.
b The Hg concentration is near the detection limit for the metal
  removals cannot properly be calculated.
and
                                    827

-------
         fable 14.   Metals Concentration Factors into Sludges
                    in Control Treatment System.
Metal
Ag(a)
As^a'
Ca
Cd
Cr
Cu
Fe
HgU)
Mg
Mn
Ni
Pb
Zn
Inf.
(rag/1)
8.0
20.6
86.0
20.9
0.63
0.80
4.29
< 2.0
17.6
0.65
0.45
0.88
1.24
Return
Act.
Sludge
(mg/1)
117
156.6
106
88
15.8
18.0
42.6
9.0
24.0
10.7
4.5
15.1
19.0
RAS
Cone.
Factor
14.6
7.6
1.2
4.2
25.1
22.5
9.9
> 4.5
1.4
16.5
10.0
17.2
15.3
Primary
Sludge
(mg/1)
179
114
524
139
20.4
31.0
51.5
18.0
64.3
20.5
14.6
32.2
46.4
P.S.
Cone .
Factor
22.4
5.5
6.1
6.7
32.4
38.8
12.0
> 9.0
3.7
31.5
32.4
36.6
37.4
a Micrograms/liter.
                                    828

-------
Table 15.  Metals Mass Balances in Control Treatment System.
Parameter
Ag
As
Ca
Cd
Cr
Cu
Fe
oo
S Hg
Mg
Mn
Ni
Pb
Zn
Cl
F
S04
Si02
TDS
Percent
Influent
Primary
Effluent
112.3
97.3
93.7
80.7
80.6
70.9
56.6
< 100.0
101.8
84.2
59.8
65.6
102.7
102.5
116.9
96.8
103.1
93.6
of
in
Primary
Sludge
10.7
0.3
2.9
3.1
15.4
18.4
5.7
< 0.4
1.7
15.0
15.3
17.4
17.7
0.6
0.1
0.1
0.7
0.8
Mass
Balance
Primary
Clarifier
123.0
97.6
96.6
83.9
96.0
89.3
62.3
< 100.4
103.5
99.2
76.1
83.0
120.5
103.1
117.0
96.9
103.8
94.4
Percent
Influent
A.S.
Effluent
61.1
78.4
91.5
36.7
52.5
19.4
22.9
of
in
Waste
A.S.
34.6
17.9
0.0
9.9
59.1
53.0
23.4
< 99.5 < 10.9
98.8
59.8
38.8
12.2
36.0
105.1
113.4
97.5
86.2
87.8
3.2
38.6
23.3
40.5
36.1
2.5
2.0
0.3
11.0
4.4
Mass
- Balance
Total
System
106.4
96.5
94.4
49.8
126.9
90.8
52.0
100.8
103.8
113.4
77.4
70.1
89.9
108.2
115.5
98.0
97.9
92.9

-------
spiking sequence such that the  control  system was  essential to assess the
metal impact performance.  While the principal operating control, the sludge
retention time (SRT), was varied from below 2 to over 12 days, most of the
spiking operations were  performed  with about 5- to  8-day SRT.   The  data
analyses  have been  completed  for  three  of  the  metals.    The  chromium
evaluation is ongoing.

     In addition to the conventional operations and  water quality parameters
(Tables 3 and 4), the spiked and control  systems were monitored for effluent
turbidity and their mixed liquors microscopically examined using dark field
and 645X.  A  series  of photomicrographs were taken to document changes in
microbiota as the metal concentration was increased.

     The experimental results were used to evaluate  the principal effects of
the metals addition on the plant operation as  a function of increasing metal
concentration.  The studies also provided process and  system metal removals,
metal partitioning to the plant's sludges, and passthrough  of the metal from
the  treatment  plant; all  as  functions  of  the  spiked  influent  metal
concentration.

     Limited highlights of the  results are presented in Tables 16 and 17 and
Figures 3-8.  Table  16 presents the  effects  of three of the metals on the
activated  process.    Significant deterioration of  the  overall  plant  per-
formance generally requires substantial influent metals concentrations, well
above typical background metals concentrations.

     The metals concentration correlations,  usually as a function of system
or  process  influent   concentration,  exhibited reasonable  correlation co-
efficients  (Table  17)   and  can  be  used  to predict  process or  system
performance for the  removal of metals.  The graphical presentations of the
metals concentrations in the spiked systems  process and  sludge streams as a
function of the influent metal concentration  (Figures 3-5) reveal a break-
through  discontinuity for Cd  in  the  activated sludge effluent  but  con-
tinuously  increasing final  effluent breakthroughs  for Pb  and Hg.   Repre-
sentative graphical  presentations  for the  concentration  correlations on the
spiked metals are provided in Figures 6-8.

TOXICITY REMOVAL

     Even with extensive removability data and occurrence  concentrations on
the individual toxics, health or ecosystem effects  from  the complex mixture
of metals in municipal or industrial wastewaters and  treated  effluents are
very difficult to evaluate.  A biomonitoring  approach to assess health and
ecosystem impacts and to  supplement  the specific occurrence and removal data
is being evaluated in the MERL toxics studies.

     The EPA's Newtown  Fish  Toxicology Station in Cincinnati is assessing
removal  of toxicity from the  spiked and  control  raw  wastewater during
conventional  treatment  of the MERL toxics  studies.    The Fish Toxicology
Station is using fathead minnows,  rainbow trout and Daphia magna as testing
targets in 96-hour static (LC50) acute toxicity tests  for the fish and in 48-
hour static (EC50) acute  toxicity tests for Daphia magna.  The acute toxicity

                                    830

-------
              Table  16.   Summary of Effects of Metals Spiking
                         on the Activated  Sludge Process.
Metal Concentration, mg/1, Entering
Activated Sludge Process
Effect Observed
Breakthrough of metal into
secondary effluent
Increase in effluent COD
Increase in SVI
Inhibition of nitrification
Decrease in respiration rates
Cd
2.0
4.1
8.6
8.6
10-20
Pb Hg
continuous continuous
-
0.76 .16
1.7 12.5
3.3
Decrease in colonial stalked
  ciliates

Significant turbidity increase

Floe destabilization and
  complete process failure
 8.6

30.5
30.5

30.5


71
3.3
                                   831

-------
            Table 17.   Removal Correlations for Cd, Pb and Hg.






I.    Activated Sludge  Effluent -y vs Primary Effluent -x:




     Cadmium (mg/1):




          log y     =     0.731 log x  -0.964           r = 0.89




     Lead (mg/1):




          log y     =     1.060 log x  -1.070           r = 0.93




     Mercury




          log y     =     0.890 log x  -0.618           r » 0.95









II.   Primary Sludge -y (Mg/Kg) vs Influent Wastewater -x (mg/1):




     Lead:




          log y     =     0.31 log x  +2.34             r = 0.86




     Mercury:




          log y     =     1.248 log x  -1.756           r = 0.96








III.  Waste Activated Sludge -y (mg/kg) vs Primary Effluent -x  (mg/1)




     Cadmium:




          log y     =     1.005 log x  +3.077           r = 0.96




     Lead:




          log y     =     1.140 log x  +2.350           r = 0.97




     Mercury:




          log y     =     0.653 log x  +1.254           r = 0.90
                                    832

-------
1000
 500
               \  I  I ITII	!	1—I I  I I I II	1	1	1  I I I  I II	1	1	1  I  I I IL
 0.01
   0.01
0.05   0.1           0.5    1             5     10
             NOMINAL SPIKE CONC. ( MG/L )
                                                                        50    100
             Figure  3.   Cadmium Concentrations  in Spiked  System.
                                     833

-------
10,000 F
 1,000
    100 :
o
o

.a
Q.

O
UJ
>
o:
UJ

m
o
                                    RETURN

                                    ACTIVATED
                                    SLUDGE
ACTIVATED
SLUDGE

EFFLUENT
   0.01
      0.01
           100
            ACTUAL  Pb   SPIKE  CONC     (mg/l)
            Figure 4.  Lead  Concentrations in Spiked System.



                             834

-------
 1,000,000
   100,000
    10,000
o
z
o
o.

o»
I

o
UJ

(T
bJ
V)
CD
o
1,000
       100
        10
                1   1  1   1 1 1 1
                            1   1  1   1 1 1 1
                             PRIMARY

                             SLUDGE
                                        A*/
                                        *7
                       RETURN

                       ACTIVATED

                       SLUDGE  „
                1   1  1   1 1
                             PRIMARY

                             EFFLUENT
                            1   1  1   1 1 1 1
1   1  1  II 1
                                          7-V
                                             ACTIVATED


                                             EFFLUENT
1   1   1   1 1 1
          100
                     1,000            10,000

                   INFLUENT Hg  CONC  (ug/l)
         100,000
      Figure 5.  Mercury Concentrations in  Spiked System.

                            835

-------
CO
CO
01
                   10,000
                .a
                Q.
                ill
                o
                Q
                ID
                o:
                <
                5
                (E
                Q.
1,000
                      100
                                    '   I  I  I I I I
                               log y -

                             0.31 logx +2.34



                               r« 0.86
                                               I                    10


                                           Pb  SPIKE  CONC    (mg/l)
                                                                   100
                        Figure 6.   Primary Sludge Pb Concentrations as a Function

                                   of the Influent Pb Concentration.

-------
  100,000 r	1	1   I  [  I I I  I
   10,000
o
o
    1,000
      100
        O.I
       	1	1	1  |  I  I I I





           log y =


        1.14 log x + 2.35







          r = 0.97
T	1	1  I  I I  I U
   I                       10


PRIMARY  EFFLUENT   Pb   (mg/l)
                                                                  I	I
                                                                       I  .  . I
                                                                             100
          Figure 7.  RAS Pb  Concentration as a Function  of the Primary

                     Effluent  Pb  Concentration.
                                    837

-------
     10
9     I
E
UJ
UJ
o
o
to




UJ
t-


>
     0.1
    0.01
                               10
       log  y =



    0.90 log *  - 1.07




        r = 0.83
100
1000
                              INFLUENT  Pb   (mg/l)
         Figure 8.  Lead  Concentration in  the  Activated Sludge  Effluent

                    as  a  Function of Influent  Pb Concentration.
                                     838

-------
 reductions by the treatment systems are based  upon the reduction of lethal
 units measured in the influent and effluents  from the treatment systems or
 processes.  The lethal units are  calculated from:

      LU.   =                   100%
                  LC50 or EC50 in percent wastewater

      Chronic toxicity residuals  are  also determined in the wastewater  or
 effluents using the early-life-stage (ELS) chronic  test on  fathead  minnow
 embryos.   The  chronic exposures  with various dilutions of  wastewater  are
 initiated with eggs less  than  24 hours old and  continue through 30 days after
 hatching. The  effects on embryo survival and  larvae survival and growth are
 measured  to  estimate  chronic  toxicity of the wastewater to the  fish embryo-
 larvae as a  representative ecosystem organism.

      Finally,   an  assessment  of  mutagenicity reduction  by the  treatment
 systems has been recently initiated using the Ames Test as the indicator.  The
 work  with   the  Cincinnati  Health  Effects  Research  Laboratory  involves
 extracting  the raw wastewater,  primary  effluent,  secondary effluent,  and
 chlorinated  secondary  effluent  from an  unspiked  treatment  system  with
 methylene chloride. The extraction separates the  bacteria and viral cells in
 the wastewater from the toxic organics.   The organic extracts  are solvent
 transferred  to dimethyl sulfoxide (DMSO) and  the DMSO extracts are used in
 the Ames test to assess the reduction in mutagenicity by the treatment
 processes.   Results  are not yet available on this work.

 Ecosystem Toxicity Removal

      The  ecosystem toxicity  work was  performed during  the semi-volatile
 organics  studies.   The  operating conditions, water quality levels  in  the
 wastewaters  and effluents, and specific toxics concentrations encountered in
 the  semi-volatile  studies  describe  the  wastewaters  used  by  the  Fish
 Toxicology Station.

      The  results to date on the acute toxicity reductions are summarized in
 Tables 18 and  19.  In Table 18,  the unspiked raw wastewater exhibited moderate
 acute toxicity which  increased when the priority  pollutants were added.  The
 conventional treatment system essentially eliminated the acute toxicity from
 the wastewater  in the control (unspiked)  study.  Conventional treatment also
 reduced but  did not eliminate the acute toxic   effects of  the effluent from
 spiked wastewater  system.   The initial  study  also  revealed  that  de-
 chlorination of chlorinated  secondary  effluent  essentially prevented  in-
 creased  acute  toxicity  from  chlorination  (Table  19)  of  the  secondary
 effluent.

      The  embryo-larvae chronic testing for five percent and lower concentra-
 tions of unchlorinated  final effluent  from  the  spiked system  (Table  20)
 revealed  no  statistical  difference in the embryo/larvae survivals or in the
 growth of the  larvae-juveniles  compared  to the  control.   The application
 of chlorination/dechlorination  to the  final effluent, however,  produced
(Table 21) a  statistically  significant reduction in larvae-juvenile survival
 and in growth rate at the 5 percent concentration level of plant effluent in
 diluent water.

-------
               Table 18.  Acute Toxicity  (96-hour) of Municipal  Wastewater Before and After
                          Conventional Wastewater Treatment:   Fathead Minnow - Phase I
OD
-&
LC-50, Percent
Sample
Date
12-14-79
12-19-79
1-16-80
1-22-80
4-2-80(b)
4-15-80(b)
4-24-80(b)
5_5_80(c)
5-13-80(c)
6-4-80
3 Spiked samples
b Slight excess
Unspiked
Influent
-
—
30
11.0
(9.3-12.5)
9.3
(7.9-11.2)
30
10.2
(8.5-13.0)
18.5
(16.5-20.7)
10.1
(98.3-11.1)
20.6
(17.8-25.3)
- mixtures of 22
Unspiked
Effluent
100
64.4
(59.2-70.5)
100
100
100
100
100
100
100
100
Percent
Toxicity
Reduction
-
-
100
100
100
100
100
100
100
100
organic priority pollutants
control fish mortality in sample
c Samples were 24-hour composites - others were
NOTE: Toxicity reductior calculations based on
NllTnViOT*c in r»a Y"o-n f"Vic. o o o aT*o QS1^ r* r^n 4~i H £»r»r*
s .
grab samples.
lethal units
o 1 t -m-i f* c
LC-50,
Spiked(a)
Influent
-

4.6
(3.5-16.2)
2.7
(2.2-3.3)
9.5
(8.1-11.1)
4.5
(3.2-5.8)
4.3
(3.3-6.5)
5.8
(4.8-7.6)
6.5
(5.6-7.6)
1.9
(1.0-2.3)
Percent
Spiked (a)
Effluent
36.1
(28.5-43.4)
22.3
(18.7-25.8)
13.1
(10.0-16.0)
16.1
(13.6-19.0)
35.5
(30.3-43.3)
6.6
9.4
(7.9-11.5)
30
30
8.0
Toxicity
Reduction
-
-
65
83
73
32
55
81
78
76
in pilot treatment system.

(LU = 10° )
LC50





-------
       Table 19.  Acute Toxicity of Municipal Wastewaters^3) With and Without Chlorination.
Sample
Date
6-30-80


7-7-80


7-16-80


7-24-80


7-31-80
8-5-80

Test
Animals
Fathead Minnow
Rainbow Trout
Daphnia magna
Fathead Minnow
Rainbow Trout
Daphnia magna
Fathead Minnow
Rainbow Trput
Daphnia magna
Fathead Minnow
Rainbow Trout
Daphnia magna
Fathead Minnow
Daphnia magna
Fathead Minnow' 8'
Daphnia magna
Influent
(10.4-14.2)^)
_(e)
(14.6-22.3)
15.1
(12.8-19-7)
-
1.6
12.8
(11.3-14.9)
-
1.6
10.5
(8.6-13.3)
-
1.9
(1.0-2.6)
5.4
(4.1-6.8)
1.6
1.6
1.6
Pre-Chlorinated
Effluent
27.9
(24.4-32.0)
9.7
(7.2-12.8)
16.8
(14.3-19.7)
44.7
(40.4-51.2)
17.2
' (14.7-20.8)
23.5
(22.0-34.4)
39.9
(34.6-44.9)
13.4
(10.2-18.7)
6.4
(1.9-11.4)
24.5
(19.3-29.9)
17.2
(14.7-20.8)
21.8
(18.0-25.6)
32.3
(26.5-41.2)
9.1
(6.7-12.2)
5.0
22.6
(17.2-27.8)
Chlorinated/
Dechlorinated
Effluent
32.3
(28.0-38.1)
14.2
(10.8-20.2)
11.2
(9.4-13.5)
60
17.8
(15.4-21.4)
9.8
49.0
(42.6-61.1)
16.1
(13.4-19.7)
10.2
23.2
(18.0-28.3)
17.8
(15.7-21.4)
8.0
42.7
(34.0-52.4)
1.6
5.5
15.2
(10.8-20.1)
Percent
Toxicity
Reduction^)
63
-
+ 51
75
-
16.3
74
-
84
55
-
76
88
0
71
89
a Influent wastewater continuously spiked with 22 organic priority pollutants.
b Toxicity reduction based on lethal units of influent and chlorinated/dechlorinated effluent.
c Fish - 96-hr LC50 percent waste.
d 95% confidence limits.
e Indicates no data.
f Daphnia magna 48-hr EC50 percent waste.
8 Slight excess control fish mortality.
                                               841

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                     TABLE 20.  Survival and Growth of Early-Life-Stages  of  Fathead Minnows

                                Exposed to Activated-Sludge Effluent  in Spiked  System.
oo
.£»
ro
Nominal Embryo
concentration survival
5.0 88
82
2.5 92
86
1.2 86
88
0.62 88
88
0.31 88
90
0.16 86
92
Control 90
88
Larval- juvenile
survival (%)
at 30 days
_
93
97
90
100
93
_
90
97
93
100
80
93
100
Juvenile weight (mg)
mean + S . D .
at 30 days
113
117
167
155
167
178
197
207
207
196
183
200
196
188
+ 38
± 36
+ 49
± 36
+ 49
+ 49
+ 53
+ 60
+ 55
+ 64
+ 57
+ 35
+ 53
+ 63
Juvenile length (mm)
mean + S.D.
at 30 days
20.6 +
23.5 +
23.1 +
22.9 +
23.3 +
24.1 +
24.5 +
24.7 +
24.5 +
24.4 +
23.9 +
24.6 +
24.3 +
24.5 +
2.4
1.5
2.4
1.7
2.5
2.2
2.8
2.7
2.3
2.7
2.1
1.5
2.1
2.5

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                TABLE 21.   Survival and Growth of Early-Life-Stages of Fathead Minnows Exposed
                           to Chlorinated/Dechlorinated Effluent from Spiked  System.
Nominal
concentration
5.0
2.5
1.2
00
to
0.62
0.31
0.16
Control
Embryo
survival
86
80
90
92
88
80
94
90
86
82
78
92
86
82
Larval- juvenile
survival (%)
at 30 days
10(a)
7 (a)
100
93
80
93
83(a)
67(a)
83
100
97
97
100
90
Juvenile weight (mg)
mean + S.D.
at 30 days
66 + 8 (a)
72 _+ 12 (a)
130 + 52(a>
129 + 47 (a)
165 + 53
162 + 53
173 + 54
165 + 29
170 + 44
203 + 49
191 + 40
200 + 44
213 + 67
186 + 46
Juvenile length (mm)
mean + S.D.
at 30 days
18.3 + 0.58
19.0 + 1.4
22.3 + 2.5
21.8 + 2.4
23.4 + 2.6
23.0 + 2.4
23.4 + 2.5
23.1 + 1.2
23.9 + 1.9
24.7 + 1.6
24.0 + 1.7
24.6 +_ 1.6
24.8 + 2.3
24.8 + 2.2
a  Significantly different (P=0.05) from control,

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SUMMARY

     The U.S. EPA's Municipal Environmental  Research Lab  is assessing,  at
it's Test and Evaluation Facility in Cincinnati, the removability  of toxic
substances from municipal wastewater by conventional wastewater treatment
processes.   The raw wastewater used at the Test Facility is a mixed domestic/
industrial wastewater from the highly industrialized Mill Creek area of
Cincinnati.  The studies feature pilot-scale primary/secondary treatment of
the raw wastewater spiked with selected priority pollutants (metals and
organics).   In the studies, the treatment plant performance on spiked waste-
water is compared to the performance of identical treatment-on the unspiked
raw wastewater.   The assessment employs costly analyses (GC/MS and atomic
absorption methods) for the selected toxic substances in the various process
streams and sludges of the conventional treatment plant.

     From  the studies  to date, conventional  treatment  is  generally  effective
in removing selected toxic substances, typically achieving better than 90%
removal of organics and from 60-80% removal of the metals.  A few of the toxic
substances, however, pass through into the treatment plant final effluent in
sufficient concentrations which,  based upon EPA recommended water quality
standards,  may present a possible environmental hazard.

     Even with extensive removability data on  the  individual  toxic  substances,
health effects or ecosystem effects from the complex mixtures of materials in
municipal or industrial wastewaters and effluents are very difficult to
evaluate.  A biomonitoring approach to assess health and ecosystem effects is
also being evaluated to supplement the specific toxic substance removal data
being collected in the EPA studies.  The EPA's Newtown Fish Toxicology Station
in Cincinnati is assessing the removal of acute toxicity to ecosystems from t..e
spiked and control raw wastewater during various stages of treatment.  The fish
toxiciology station is using fathead minnows, rainbow trout, and Daphnia magna
as testing targets in 96hr static (LC5Q) acute toxicity tests for the fish and
in 48 hr static (EC5g) acute toxicity tests for the Daphnia.  The acute toxicity
reductions by the treatment systems are based on the reduction of lethal units
(L.U.) measured in the plant's influent and effluent.

     Chronic  toxicity  residuals are also determined  in the  final  effluents
from the spiked system using the early-life-stage (ELS) chronic test on fathead
minnow embryos.   The effects on embryo survival and on larvae survival and
growth are measured to estimate chronic toxicity for various dilutions of
plant effluent.

     From  results  to date,  the unspiked raw  wastewater exhibited  moderate
acute toxicity which increased when the priority pollutants were added.  The
conventional treatment system essentially eliminated the acute toxicity from


                                     844

-------
control (unspiked) wastewater.  Conventional treatment also reduced, but did
not eliminate, the acute toxic effects from the spiked wastewater.

      The  initial  study  has  also revealed  that  dechlorination  of  chlorinated
secondary effluents essentially prevented increased acute toxicity from the
chlorination.  The embryo/larvae chronic testing for 5% and lower concen-
trations of unchlorinated final effluent from the spiked system revealed no
statistical differences in  the embryo/larvae survivals or in the growth of the
larvae/ juveniles compared  to the control.  The application of chlorination/
dechlorination to the final effluent, however, produced a statistically
significant reduction in larvae/juvenile survival and in the growth rate of the
larvae/juneniles at the 5%  concentration level of plant effluent in  diluent
water.

      An important overall observation from  the above work on  toxic  substances
is that the treatment of the strong domestic/industrial wastewater at the
Cincinnati plant has exhibited remarkable stability over a wide range of
operating conditions and produced consistent and excellent treatment of the
wastewater, even when spiked with large doses of metals or toxic organic1'. In
contrast,  earlier experience in treating domestic wastewater over similarly
wide ranges of operating conditions has revealed operating areas where the
growth of organisms such as Sphaerotilus natans predominate in the activated
sludge process and contribute to poor settling characteristics of the sludge.
These organisms produce plant effluent deterioration through carryover of
solids.  One possible explanation to the improved treatment stability in the
Cincinnati study is that the background of toxic contaminants in the Cincinnati
raw wastewater reduces the biological competitiveness of the exposed filamentous
organisms.

      In any event, the  EPA  work indicates that the  central municipal waste-
water treatment plant potentially represents a cost effective alternative to
industrial pretreatment for the control of many toxic substances.  Use of the
treatment plant for toxics control, however, requires evaluation of the impact
of the toxics on the sludge handling and final disposal processes.  In
addition,  the use and practical management of the central municipal treatment
plant for toxicity control would greatly benefit from the availability of
suitable biomonitoring tests for determining the removal of overall toxicity,
both acute and chronic,  for health and ecosystem protection.
                                    845

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REFERENCES
1.   Natural Resources Defense Council (NRDC) et al. vs. Train 8 ERC 2120
     (DDC  1976).

2.   Feiler, H., "Fate of Priority Pollutants in Publicly Owned Treatment
     Works, Interim Report."  Report No. EPA 440/1-80/301 (1980).

3.   DeWalle, F.B., et al., "Presence of Priority Pollutants in Sewage and
     their Removal in Sewage Treatment Plants," Draft Final Report Grant
     R-806102, Municipal Environmental Research Laboratory, U.S. EPA,
     Cincinnati, Ohio.

4.   Petrasek, A.C., et al., "Behavior of Selected Organic Priority Pollutants
     in Wastewater Collection and Treatment Systems," Presented at the 53rd
     Annual conference of the WPCF, Las Vegas, Nevada (Sept. 1980).

5.   Petrasek, A.C., et al., On-going work at the U.S. EPA Test and Evaluation
     Facility, Municipal Environmental Research Laboratory, Cincinnati, Ohio.

6.   Petrasek, A.C., "Distribution and Removal of Metals in a Pilot-Scale
     POTW," Internal Report, U.S. EPA, Municipal Environmental Research
     Laboratory, Cincinnati, Ohio.

7.   Petrasek, A.C., "Inhibition of the Activated Sludge Process by Cadmium,"
     Internal Report, U.S. EPA, Municipal Environmental Research Laboratory,
     Cincinnati, Ohio.

8.   Petrasek, A.C., "Inhibition, Removal, and Partitioning Interactions
     between Lead and the Activated Sludge Process," Internal Report, U.S.
     EPA, Municipal Environmental Research Laboratory, Cincinnati, Ohio.

9.   Petrasek, A.C., Mercury Report in preparation, U.S. EPA, Municipal
     Environmental Research Laboratory, Cincinnati, Ohio.

10.  Petrasek, A.C., Chromium Report in preparation, U.S. EPA, Municipal
     Environmental Research Laboratory, Cincinnati, Ohio.

11.  Horning, W., Robinson, E., and Petrasek, A.C., "Organic Priority
     Pollutant Toxicity Reduction by Conventional Wastewater Treatment,"
     Draft Report, U.S. EPA, Environmental Research Laboratory-Duluth,
     Newtown Fish Toxicology Station, Cincinnati, Ohio.

12.  Pickering,  Q.H., Report in Preparation, Newtown Fish Toxicology Station,
     Cincinnati, Ohio.

                                    346

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13.   Convery,  J.J.,  Cohen, J.M., Bishop, D.F., "Occurence and Removal of
      Toxics  in Municipal Wastewater Treatment Facilities," Presented at the
      Seventh Joint United  States/Japan Conference, Tokyo, Japan, May 1980.

14.   Methods for Chemical  Analysis of Water and Wastes, EPA-600/4-79-020,
      Environmental Monitoring  and Support Laboratory, Cincinnati, Ohio
      (March  1979).

15.   Standard  Methods  for  the  Examination of Water and Wastewater,  14th Ed.,
      APHA, Washington, B.C.  (1976).

16.   Federal Register, 44  (233), December 3, 1979, "Guidelines Establishing
      Test Procedures for Analysis of Pollutants, Proposed Regulations,"
      pp. 69526-69558.

17.   "Interim  Methods  for  the  Measurement of Organic Priority Pollutants
      in  Sludge," U.S.  EPA, Environmental Monitoring and Support Laboratory,
      Cincinnati, Ohio, September 1979.

18.   Warner, J.S., et  al., "Analytical Procedures for Determining Organic
      Priority  Pollutants in Municipal Sludge," EPA-600/2-80-030, Municipal
      Environmental Research Laboratory, U.S. EPA, Cincinnati, Ohio, March
      1980.

19.   Bishop, D.F., "GS/MS  Methodology for Priority Organics  in Municipal
      Wastewater Treatment," U.S. EPA, Cincinnati, Ohio, EPA-600/2-80-196,
      NTIS #PB81 127813, November 1980, 43 pages.

20.   Prairie,  R. , et al.,  Report in Preparation, U.S. EPA, Environmental
      Monitoring and  Support Laboratory, Cincinnati, Ohio.

21.   Kleopfer, R.D., et al., "Priority Pollutant Methodology Quality
      Assurance Review," U.S. EPA, Region VII Laboratory, Kansas City,
      Kansas  (1980).

22.   Callahan, M.A., "Water-Related Environmental Fate of 129 Priority
      Pollutants," EPA-440/4-79-029a, U.S. EPA, Washington, D.C., 1979, 714
      pages.

23.   McKee,  J.E., and Wolf, H.W., Water Quality Criteria, Publication No. 3-
      A,  State  Water  Quality Control Board, Sacramento, California (1963).

24.   Criteria  For Water Quality, U.S. EPA, Washington, D.C., U.S. Govt.
      Printing  Office,  546-312/146 1-3, 1973.

25.   Warner, H.P., "Wastewater Treatment for Reuse and Its Contribution
      to Water  Supplies," EPA-600/2-78-027, Municipal Environmental  Research
      Laboratory, Cincinnati, Ohio (March 1978).

26.   Esmond, et al., "The  Removal of Metals and Viruses in Advanced Wastewater
      Treatment Sequences," EPA-600/2-80-149 (August 1980).


                                     847

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          AN INDUSTRIAL PERSPECTIVE ON
JOINT MUNICIPAL-INDUSTRIAL WASTEWATER MANAGEMENT
              Gerald N.  McDermott
                Senior Engineer
              Environmental Control
          The Procter & Gamble Company
                Cincinnati, Ohio
The work described in this paper was not funded by the
U.S. Environmental Protection Agency.  The contents do
not necessarily reflect the views of the Agency and no
official endorsement should be inferred.
           Prepared for Presentation at:
       8th United States/Japan Conference
                       on
           Sewage Treatment Technology

                  October 1981
                Cincinnati, Ohio
                      849

-------
AN INDUSTRIAL PERSPECTIVE ON JOINT MUNICIPAL-INDUSTRIAL WASTEWATER
MANAGEMENT

G. N. McDermott, Senior Engineer


     Gentlemen from Japan, I welcome this opportunity to discuss with you
one subject in your program this afternoon.   My talk concerns  largely
policy matters, the organizational arrangement of wastewater treatment,
rather than the technical matters.

     I have looked forward to talking to you about this subject.   I  have
enjoyed the papers you have presented during the past two days and I have
taken occasion to study the papers from your previous conferences.   In
high school I experienced the value and enjoyment of working with
Japanese people.  I had the experience of sharing two years of high
school with two boys of Japanese ancestry named James Kowabata and Frank
Iwatsuki.  I was well acquainted with them because James and Frank plus
Kelly Berkeley and myself were the four llth graders selected  to be
allowed to attend honor study hall in that high school.  I learned to
appreciate the ability of Frank and James during the work solving  prob-
lems in physics and chemistry in that study period.  I learned to  benefit
from their good minds.  I had reason to remember them because  they estab-
lished grade averages better than mine.  I have lost track of  Frank  and
James over the years but no doubt they are out there making a  technical
contribution someplace.  Not only did I experience this scholarship  com-
petition but dealt with Fumico Iwatsuki, the fastest typist in the
school, and Shogo Adachi the best wrestler in my weight class.

     The subject that I want to talk to you about this afternoon is  that
of the treatment of the entire wastewaters from a community in one common
or shared system.  Such a system is one that accepts the wastewaters from
the homes, from commercial establishments and from industrial  plants and
conveys them to a shared treatment plant.  In the United States this is
often referred to as joint treatment.

     The reason I want to talk to you about joint treatment is to  be sure
you understand its advantages, its problems and its administration.

     The topic of my talk to you gentlemen today is an old and frayed
one.  Yet, it is timely to talk about this subject with you because  of
recent attention to it in this country by way of emphasis on pretreatment
programs.  A pretreatment program is a term which the Federal  agency
people brought forth about 1980.  The term speaks to the controls  and
restraints on use by industry of publicly owned wastewater treatment
works.  This Federal agency attention is new; that is the only thing new
about the subject.  The practice has existed from the very first develop-
ment of wastewater collection systems.  The first published reference I
have come across is a declaration by the Royal Commission on Pollution
Control of London.  In 1903, these gentlemen proclaimed "the most
economic way to dispose of trade wastes is to discharge them to the city
sewers and treat them along with domestic sewage".

                                     850

-------
     This joint treatment practice  has  been  followed  in  practically every
community sewer system in this country.  Only  in a  few instances have
municipalities and local industry built separate wastewater  treatment
plants.  Table 1 illustrates the number of major industries  using  the
sewer system in each of five representative  cities  in this country.

     Each of the industrial plants  included  in these  numbers are large
enough dischargers that the cities  go to the trouble  and expense of mea-
suring and sampling their wastewaters.   These  figures do not include the
small industrial and commercial users—there are at least an equal number
of them.

     The practice is widespread among the various categories of indus-
try.  Most and in some cases all of many industrial categories discharge
their wastewaters to municipal systems  as shown in  the Table 2.  All
soluble coffee plants, all but one major soap  and detergent  plant, 95
percent of the edible oil refining plants, 15  percent of paper converting
plants discharge their wastewaters to municipal systems. At the other
extreme only a small percentage of petroleum refining plants discharge
process wastewaters to municipal systems. Likewise few  if any steel
rolling, blast furnace and by-product coking plants discharge to muni-
cipal systems.  A recent EPA wastewater plant  survey  indicates on  a flow
basis industrial wastes constitute an average  of 16 percent  of municipal
wastewater treatment plant inflow.

     The practice is so common and widespread  one might  well ask if there
is any need for discussion of the subject by way of relating information
to persuade people to continue or institute  the practice. My answer is
yes there is.  There is a need for several reasons.  One is  that there
have been a couple of problems throughout the  history of the practice
which have never been completely settled. One of these  is  the degree of
control most appropriate to discharge of wastewaters  containing  fat, oil
or grease.  A second problem area is the control needed  for  stormwater
runoff from industrial plants.  Still another  is control of  slug loads—
short-time abnormal flows or masses of treatable pollutants.

     Then there is a perennial question about  fair sharing  of the  costs
among industrial, commercial and residential users.

     The most current topic of joint treatment is the control of toxics
that may be present in some industrial wastewaters.  Toxics  can  interfere
with treatment or pass through without sufficient removal.

     The Federal EPA beginning about June of 1978,  launched  a significant
part of their huge resources on a mission to control  what they chose  to
call indirect dischargers.  Indirect industrial dischargers  are  dis-
chargers to publicly owned treatment works.   The EPA had concentrated
their early efforts on control of industry that treated  their wastewaters
in their own facilities and discharged them  directly  to  public water-
ways.  This newly initiated EPA control effort directed  at  indirect dis-
                                    851

-------
chargers was a part of an interest in control of toxic  pollutants.   The
EPA had started the program of establishing limitations on toxics for
direct dischargers at about this time and it was natural to implement  at
the same time control of indirect dischargers.

     This attention to control of toxics by requiring pretreatment  pro-
grams of communities has caused an aura of alarm and a  certain confusion
in minds of non-specialists about joint treatment.  This confusion  and
excitation has caused a questioning,  a certain skepticism, a negativism
about joint treatment.  For example cities have entertained or pressed
for unreasonable and unrewarding control of ordinary compatible everyday
treatable wastes—wastes that are perfectly compatible  with transport  and
treatment in publicly owned treatment works.  Wastes that are adequately
characterized by conventional pollutant parameters  such as BOD and  sus-
pended solids.  Cities have begun to question and propose that no capac-
ity be provided for industrial growth when treatment facilities are
enlarged.  Municipalities have said to their industrial members we  do  not
have sufficient capacity for the loads of treatable wastes you are  dis-
charging; therefore we are going to limit each of you to a specified
maximum daily load.

     Some of the language in the Federal regulations on limiting excess-
ive short time loads of compatible wastes seems to  encourage municipali-
ties to limit the industrial use for compatible wastes.  When considering
a limit on a high load from industry, a consideration of the maximum
capacity of the treatment plant likely is involved. Thus the control  of
excessive loads to prevent pass through of above limit  concentrations  of
BOD may very well limit industrial use.  The need for a slug load limit
is recognized for any parameter.  We are concerned  and  have serious
objections to restrictions that will prevent ordinary day-to-day use.

     Joint treatment is threatened in the matter of eligibility of  the
share of treatment faciities built with Federal grant funds for the
treatment of the wastes from industries of the community.  The way  that
industrial users of municipal systems are dealt with in the Federal grant
program is complex.  Too complex to go into here and there is still hope
for change.  Industry believes generally that they  should be fully  eligi-
ble to use the grant supported public works just like other members of
the community are on the basis that industry has provided a significant
part of the Federal grant funds via corporate profits tax.

     My introduction of the subject to you has been long.  I wanted to be
sure you had opportunity to understand the problems and to learn the
solutions we advocate.  My talk is not going to be  nearly so technical in
terms of processes or equipment as have been the excellent discussions
you have previously heard.  I hope my dwelling on administration or
policy will be of interest.

     I would like to sell you on joint treatment.  I would like to  point
out the best road to follow in certain problem areas in its practice.   I
                                     852

-------
would like to provide assurance in the turmoil, quiet your concerns,
point out how to overcome true problems and send you back to your home as
evangelists for this cause.

     Let us look now at the advantages of joint treatment.

     The dominant one is economic.  A larger plant is simply cheaper to
construct and operate than a number of smaller ones.  This is brought
home in real terms by this graph which shows the capital costs per
million gallons per day of capacity for biological treatment plants of a
range of sizes, Figure 3.  This data is from an EPA report.  The line of
best fit to the data exhibits a marked decline in the costs per million
gallon capacity as the size increases.  Figure 4 shows the operating,
maintenance and replacement costs per 1000 gallons of normal domestic
sewage from biological waste treatment plants of a range of sizes.  There
is a marked decline in the costs as the size increases.

     Most emphatically this information proves joint treatment is lower
in costs than separate treatment.  A fair wastewater service charge
system furthermore will result in all users benefitting from lower costs,
homeowners as well as industrial users.

     I must call attention to the possibility that in some special situa-
tions an industrial plant may be able to treat their own wastewaters more
economically.  For example, for wastewaters that are highly seasonal and
where land treatment during the warm season is practical.  Another ex-
ample would be an industrial plant at a location so remote that convey-
ance costs were prohibitive.  A third situation would be an industry with
adequate and low cost land and effluent quality limitations such that an
aerated lagoon system would suffice.  But for the vast majority of situa-
tions I feel sure joint treatment is the most economic for industry and
saves the homeowner money too.

     Some lesser but important advantages include a savings in land space
devoted to treatment plants.  A single large plant takes up less space
than would a number of smaller ones.

     Some industrial wastes are lacking in the nutrients-nitrogen and
phosphorous needed.  Domestic sewage has an excess of these.  Thus joint
treatment saves the cost of chemical addition.

     Finally, the large staff of specialists in wastewater treatment that
would be found in a large joint treatment plant will do a superior job of
providing a good uninterrupted effluent quality.  A number of smaller
plants would much more likely suffer upsets and occasional poor quality
because of part-time and non-specialist operators.

     Having been convinced of the advantages of joint treatment, I would
like to lead you through some problem areas.
                                     853

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The Fat, Oil and Grease Misunderstanding

     The wastewater treatment technologists  have  suffered a great hand-
icap in control of oil-bearing wastewaters being  discharged to municipal
systems.  Early information and recommendations were  incompletely pre-
sented and easily misunderstood.  Only recently has an adequate  control
strategy been developed.  Substantial information on  treatability and
removal of oil in municipal wastewater treatment  plants is just  currently
appearing in the literature.  The equipment  and processes used in munic-
ipal wastewater treatment have changed so that many old concerns have
disappeared.  Most concerns have been moderated or eliminated.   Controls
other than limitations on concentration have been established as best
solutions.  Let me tell you the details of this subject and lay  out  for
you where I believe the practice should be in control of oil in  waste-
waters in industrial wastewaters discharged  to municipal systems.  Pre-
treatment programs have been saddled with precidents  and recommendations
that are unnecessarily harsh, and restrictive.  They  have caused economic
waste.

     One cause of the problem is the analysis for oil measures two kinds
of oil and some miscellaneous other compounds.  The two kinds of oil are
different in their significance and control  needs. Their  treatability
and therefore the restrictions that are appropriate for one are  inappro-
priate for the other.  The two kinds of substances that are generally
involved are oils of animal and vegetable origin  and  oils  of petroleum
origin.  The chemical structure of these kinds  is very different.  The
material of animal and vegetable origin is in its original form  a  struc-
ture known as a triglyceride.  A triglyceride is  the  three carbon mole-
cule to which is attached three fatty acids.  The fatty acids are
detached from the glyceride base in the making  of soap and other deriva-
tives.  The fatty acids themselves measure as oil as  are the  soap  com-
pounds made from them.  Chemists call this whole  family of animal  and
vegetable oil compounds lipids.  Remember that term as I am  going  to use
it frequently.  The petroleum kind of oil can include a hugh  number  of
structures the predominance of which in the  usual situation are  a
straight chain of carbon and hydrogen atoms.  Petroleum can  also contain
the ring form of linked carbon atoms known as aryl and cyclic  compounds.

     The lipids are natural constituents of  food  and  are virtually every-
where in nature.  They constitute a significant portion of the diet  of
people  in the United States, in Japan and other places.  Estimates have
been made that such oils constitute 25 to 40 percent  of the calories in
the average diet in this country.  They are a major constituent  in meat,
poultry, nuts, many baked goods, milk, salad dressings, etc.   They are
used as a heat transfer liquid in frying and as an anti-sticking coating
in baking.  Compounds of lipid origin are a major functional part of much
of the  household soaps and  in  some laundry products.   They are excreted
on the  skin and hair.   It is little wonder then that  they constitute a
large percent of the organic matter in domestic sewage from households.
From at least fifteen to twenty-five percent of the organic matter in
                                     854

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sewage is estimated to be lipids.   The human feces  itself  has  been  found
to contain five percent or more of oil on a dry—weight  basis*   So the
lipid type of oil is a natural and universal major  constituent of domes-
tic sewage.  Therefore, a municipal wastewater treatment plant that can-
not adequately transport and treat wastewaters containing  lipids is not
appropriate to use.  A satisfactory plant has to be able to handle  waste-
waters containing major amounts of lipids.   A look  at the  data available
on the concentration of oil in municipal wastes indicates  a range of
about 30 to 50 mg/1.

     The lipid type of oil is biologically degradable at rates comparable
to other organics such as carbohydrates and proteins.   The latest re-
searcher to make observations of this is Professor  Hrudey  of the Univer-
sity of Edmonton in Canada.  He published a landmark paper on  this  in
June of 1981.  Preceding him there were noteworthy  contributions by
Dr. James Young of Iowa State University, Dr. Perry McCarty of Stanford
University, Messrs. Pico and Watson of Kraft Foods, Dr. Loehr  of Cornell
University, and the consulting firm of AWARE with which Professor
Eckenfelder of Vanderbilt University is associated.

     Portions of the lipid in the wastewater inflow to  a municipal  system
will be separated as scum in the primaries, will be a significant con-
stituent in the primary sludge, and will be present at  a low percentage
in the waste biological sludge.  The lipids in these sludges is readily
converted to methane gas in anaerobic sludge digesters.  The kinetics  of
this conversion is such that the lipids will be converted  at higher rates
than carbohydrate and protein fractions in the sludges.  Lipids are the
major contributor of methane in such sludges.  These facts have been
established in research described in articles by Dr. O'Rourke,
Dr. McCarthy and others.

     Please understand that such bacterialogical degradation will take
place rapidly for lipids sufficiently dispersed.  The exposed  surface  of
large particles is too low relative to the quantity of  lipid to permit
rapid degradation.  Fortunately domestic sewage contains dispersing
agents which cause oil to disperse and sustain it in suspension.  Primary
settling will remove lipids in floatable size particles.   The  oil reach-
ing the biological treatment process will be, therefore, sufficiently
dispersed for rapid biodegradation.

     As for anaerobic process, the modern digestors provide enough  mixing
that sufficient dispersion of the lipids occurs.  The former problems  of
solid oily scum forming have been practically eliminated.

     We have, therefore, arrived at the point in this discussion to deal
with the heart of the matter, the decision that you may be involved in,
namely, what are the appropriate controls for the lipids in industrial
wastewaters.  The evidence I have presented established that dispersed
lipids (animal or vegetable oil or fats) are perfectly  compatible for
                                    855

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transport and treatment in municipal  systems.  Dispersed lipids are BOD
and suspended matter which biological treatment is capable of removal and
degradation.  Our position is that  no limit  is appropriate for dispersed
lipids.

     Wastewaters of many industrial categories contain significant con-
centration of dispersed lipids,  such  as

     Edible oil refining
     Margarine manufacture
     Fish oil processing
     Milk processing
     Cheese making
     Meat processing
     Poultry processing
     Candy manufacture
     Rendering plants
     Soap manufacture
     Certain food plants

     This pretreatment capital costs  for thousands of industrial  plants
to meet some arbitrary and unrewarding limit could amount to great
amounts of money.  The primary process for removal of the dispersed
lipids is dissolved air flotation enhanced by the use of chemical coagu-
lants.  In order for the recovered material to have  value it must be
treated to remove the coagulating chemicals.  The costs are such  that
there seldom is a payout in the value of lipid recovered.  We all are
conservationists to a degree and do not like to condone waste.  However,
in this situation in case after case  the dispersed lipid is not econom-
ically recovered.  The float of lipid and chemical simply becomes a waste
material.  Our recommendation is do not force this pretreatment process
on industrial users.  The treatment of these dispersed lipids in  the
municipal treatment is perfectly feasible and is  the most economic
solution.

     Lipids in a floatable form may cause distribution and fouling prob-
lems.  By floatable form is meant oil or fat in a droplet or  scum form of
sufficient bulk that the droplets will tend to rise  to the surface under
quiescent conditions.  In other words, oil or fat which will  float to  the
surface in a gravity settling system.  The settling  system in mind would
be one which was designed according to primary settling basin criteria.

     The floatable oil is removable by simple equipment and can be made
use of for animal feed or other use.   Recovery of floatable oil where
significant quantities are involved can have a return.   So the removal of
floatable oil by the provision of gravity settling  systems is a logical
pretreatment regulation.  The simple  regulation needed is  simply  a pro-
vision that floatable oil, fat and grease be removed.  Floatable  oil must
be defined in the ordinance as oil that is removed  by gravity settling in
a facility meeting design guidelines  of the district.  The only decision
the agency must make is whether or not to require an industrial user  to
                                     856

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install a gravity settling system for floatable  oil  removal.   In most
cases the decision will be obvious and undisputed.   In  a  rare  case  some
testing may be necessary to learn of the presence or absence of signif-
icant quantities of floatable oil in an effluent.  A simple bench scale
test can be designed to establish this.  There is no need to become con-
cerned over a small quantity of floatable oil because after all there  is
considerable floatable lipids in household wastes.

     The wastewaters from restaurant and food preparation establishments
are a frequent target of control agencies in control of incidence of
obstruction of sewers.  One major city has pursued a policy for such
control which has worked well.  After finding a  sewer obstruction in the
sewer serving such establishments the owner is required to install  a
suitable size gravity separation system.  These  are  called fat traps in
the restaurant business.  In no case has an obstruction incident occurred
after such a facility was installed in this one  city's  experience.

     There is no need to try to relate an oil concentration to likelihood
of obstruction of sewers.  Ordinances use general descriptive  language
prohibiting materials that cause obstructions.   This control suffices.
It is just as easy to police good operation of a fat trap as it is  to
police for a concentration violation.

     You may have noted my preceding remarks were directed at  the
lipids—their treatability and their logical control.  I  earlier men-
tioned another kind of oil—petroleum oil.  Petroleum oil is referred  to
also as hydrocarbons.

     Hydrocarbons are not nearly as biodegradable in aerobic systems as
are lipids.  They are not degradable at all anaerobically. These facts
do not mean that they are not removable in a municipal  treatment plant.
Some will be degraded as it becomes associated with  suspended  biological
matrix and remains under treatment for long periods. Other such oil may
find an outlet through being included in the residues disposed of by
incineration or otherwise.

     However, investigations have shown that there is a limit  to the con-
centration of hydrocarbons which can be allowed  to reach  the biological
floe.  Data I have seen indicate that when the concentration of hydro-
carbons in the feed is greater than about 25 mg/1 some  of the  floe
particles will have a specific gravity the same  as water  and will not
settle in the final clarifiers.

     In the anaerobic part of the process, anaerobic sludge digestion,
petroleum oil in the skimmings feed to the digester  will  rise  into  the
digester supernatant.  When this supernatant is  returned  to the raw
sewage the oil can become again part of the skimmings.  Thus there  is
created a recirculating oil-laden stream within  the  treatment  plant.

     Therefore, a limit on hydrocarbons in the discharge  of users to the
system is a logical element of a pretreatment program.  Since  about


                                     857

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25 mg/1 in the total mix of  community wastes  received at the treatment
plant is no problem, a higher concentration in  individual plants effluent
can be allowed.  Such a concentration can be  selected appropriate to the
particular wastewater system.  An analytical  method  for hydrocarbons has
been available in standard methods since the  Fifteenth Edition.

     As a final point, I want to mention that in  early literature,  in
manuals of practice of the Water Pollution Control Federation, in early
textbooks on treatment technology, a limit of 100 mg/1 on oil—total
fats, oil and grease that is—was recommended.  This was a mistake, was
used in a way not originally intended,  and is no  longer a recommendation
of the Water Pollution Control Federation or  the  United States Environ-
mental Protection Agency.  In spite of  the fact that city after city has
this limit in their ordinance it is not needed  and is inappropriate.
This is witnessed by the fact that very few cities enforce it.  So  my
advice to you is not to follow that precedent.

Rainfall RunoffFrom Certain Areas of Industrial  Plants

     There is another rather minor appearing  problem that  I would like to
call to your attention.  The managers of municipal systems will in  many
cases do their very best to minimize the flow of  rainfall  runoff  into  the
sewers leading to their treatment plant.  Regulations will typically pro-
vide that no stormwater is allowed to be discharged  to  the municipal sys-
tem.  Campaigns to find roof drain connections  and leaky manhole  covers
and the like are commonly conducted.  Yet many  industries  will find them-
selves with a rainfall runoff from limited areas  of  the industrial  plant
which is polluted with leaks, spills, dusty materials,  etc.   The  areas
involved are those along the railroad siding  or the  truck  stations  where
bulk materials are unloaded.  Typically there will  be pumps  at  these
places.  The locations I am speaking of will  not  be  inside of buildings
or under roof.  Consequently the rain will fall on  these areas, wash off
any leakage or spill that is there and produce  some  polluted wastewater.
A strict sewer use code will not allow this to  be dumped  into  the sani-
tary sewer.  Segregation and storage of this  water  is very costly and
troublesome.  We believe that the runoff from these  limited  spill prone
areas should be considered a legitimate industrial waste and be allowed
to be discharged with the other wastes to the sewer.  The  volume  is small
and will not stress  the usual system.  The industries  generally provide
spill protection such as curbs or retention tanks for these  areas so  that
a large spill may be kept from the sewer.  Sometimes discharge  of rain-
fall can be delayed  somewhat.

Control of Peak Loads From Industry

     Another hard-to-deal-with subject that I mentioned in the introduc-
tion is control of  industrial loads.  The management of a municipal sys-
tem must be supplied information  on  the discharge schedule,  average daily
volume, and average  daily load of the significant industrial users.  The
information is needed for design, for operation,  and for revenue program
                                     858

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planning.  Likewise the peak load and flows  expected must  be  known.  Many
industries have a difficult time maintaining a  constant  load  for  exten-
sive periods of time.  Equipment fails,  raw  materials  change,  people fail
and some accommodation to variation on loading  is  a necessity.  So there
can be a problem with high short-duration volumes  or mass  discharge of
pollutants—a high day or high week.   A short period,  high load-for say
an hour or two is usually meaningless because the  dispersion  of the load
in other flow in the system in the sewers and at the treatment facility
will average out the peak so that the effect is the same as a daily or
half day peak.

     Most treatment facilities have a built-in  ability to  accept  and
adequately handle a peak daily load.   Domestic  sewage  has  a daily varia-
tion in flow and strength which allows off peak hours  for  catch up after
unusual industrial loads are received.  Activated  sludge has  a remarkable
ability to handle a great increase without a marked impact on effluent
quality.

     A real potential problem with an excessive peak load  would be when
the effluent quality is significantly adversely affected.   In most
receiving water situations the damages from  excursions out of the ideal
water quality standards for short times  is not  serious.  The  criteria are
based on long-term exposure.  Short term modest excesses could not be
considered serious.

     A good way to regulate industrial peak  loads  via  a  general easily-
interpreted meaningful ordinance has  not been invented.

     Limitations on concentrations is one approach.  It  is okay for
toxics.  For compatible pollutants it is too simplistic  to warrant atten-
tion.  The mass of pollutants is the  critical issue.   Any  such concen-
tration limit is anti-conservation of water. A concentration limit on
compatible (easily treated) pollutants is not a good way to control loads.

     Equalization requirements is another approach.  Cities have  been so
extreme as to suggest 24-hour retention basins  for evening out effluents
to their system.  Equalization basins require aeration to  keep odors from
developing.  They need mixers to keep solids from  accumulating.   Equali-
zation basins remove nothing.  Generally they are  not  cost effective.
The money would better be spent on more  treatment  plant  capacity.

     A definition of an unlawful load is a load the discharger knows or
has reason to know will cause interference with the treatment facili-
ties.  This is an illusion as a practical solution in  my opinion. The
provision is an invitation for debate, for endless talk  and controversy,
and ill-will and external frustration.

     What then can be recommended in  the face of absence of precedence of
practical control systems?  My suggestion is to obtain needed control by
addressing this subject in each industrial permit. The  peak  volumes and
loads could be specified for those industrial dischargers  large enough to
                                     859

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be of concern.  Each specification could  be  tailored  to specific circum-
stances.  Real problems only could be  addressed and most economic control
assured.

Fair Charges to Users

     Arriving at fair charges for  wastewater services for all users	
commercial, residential, and industrial	is a complicated matter.  A
rational and detailed analysis can produce a revenue  program that can be
defended as fair.  Technical societies such  as the American Society of
Civil Engineers, the Water Pollution Control Federation, and the American
Public Works Association have jointly  sponsored manuals setting for the
principles for a fair revenue program.

     The basic philosophy of a fair charge system is  that the users and
beneficiaries of the system be made to pay in proportion to the costs of
providing the use and benefit each received. Key to  application of this
philosophy is the proper recognition of  the  cost  causative agents and the
uses and benefits of the system.   For  instance in distributing capital
costs each element of the system—the  pipes, pumps, treatment tanks—is
assigned to the appropriate cost-causing  agent or agents.  Pipes or
sewers for example are sized to carry  certain peak flows therefore the
costs should be distributed according  to  the peak flow of each user.
Another example would be the cost-causing agent assigned the air blowers
for the activated sludge system.   The  air blowers are for the ultimate
purpose of removing BOD and are sized  to  deliver  enough air for the BOD
load.  Therefore, the capital cost of  the blowers is  assigned to BOD of
each user.

     A necessity to fairness of application  of this principle is that all
the uses must be recognized and all the  cost-causing  agents in the system
recognized.  The uses that are neglected in  defective cost distribution
systems can be the use for the conveyance and treatment of stormwater,
the use for conveyance of infiltration,  and  the capacity for future
users.  In every system in spite  of trying to exclude stormwater by
careful construction there will be experienced significantly higher flows
after storms.  Likewise practically every system  in  this country exper-
iences a great deal of leakage or infiltration.   A  representative case
will have fifty percent of the annual  flow attributable to infiltration.
Logical planning indicates that considerable capacity for growth ought  to
be included in any conveyance and treatment  system.   These  three uses and
perhaps others are referred to as community  costs or  public costs by  some
rate engineers.  The insinuation  is that these uses  cannot be identified
with any particular user of the system.   For example  most of  the storm-
water will originate in the streets which are of  course publicly owned.
Infiltration comes into the sewers owned by  the district  in the  streets
largely.  The revenue program for these  public use  related costs must be
carefully thought out.  The recommendation in the guidance  referred  to
above is that these costs be considered  a general obligation  of  the city
and therefore should be assigned  according to ownership of  property  in
the city, in other words from property taxes.  In many cases  in  this


                                      860

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country it is not practical to levy new taxes.  Property benefit charges
may be possible.  An alternative is to distribute costs equally per
customer or equally per customer in each class.

     The point I wish to leave with you is that  the simple concept of
sharing costs proportionate to use and benefit is complex in its appli-
cation.  If public use is not recognized the large deliberate users such
as manufacturing industry are assigned an unfairly large portion of the
public use costs.  For example an industry that  discharges 25 percent of
the flow would in a simple apportionment receive 25 percent of the costs
for stormwater, infiltration, and future capacity in the system.  This is
obviously not fair.  So I advise you to get the  help of experts in
designing your revenue program.  There are engineering firms who have the
expertise and experience.

Toxic Pollutants

     The portion of this subject which I have left for last is the part
of the subject of use by industry of a municipal wastewater system that
has caused so much recent concern and is probably the first that comes in
your mind when contemplating the subject.  The topic is the discharge of
toxics to the municipal system.  In earlier years of control of indus-
trial use of these systems the effort was directed largely at the metals
such as copper, nickel, and zinc.  Concerns were 1) interfering with the
biological processes and 2) harmful effects on fish.  In recent years the
interests have broadened the meaning of a great  range of effects such as
causing birth defects, mutagens, cancer, etc., harm to any organism in
the environment, bio-concentration, etc.  The Federal law has focused
attention on over 100 organic compounds with the potential of exerting
some such environmental effect in wastewaters.  Research on health and
environmental effects being conducted will likely bring attention to
other compounds in time.  Experience to date indicate that a monitoring
program will not be easy, it will not be cheap.   A practical problem in
analysis may make it very difficult to learn whether the material is
present or not in the mix of biological residues in a treated effluent.
The control scheme proposed by the Federal EPA could be so complicated
that municipal administrators will find it too much administrative
trouble to use.  This could harm the cause of joint treatment severely.
Even though the vast majority of such organic compounds will be subject
to biological degradation and will, with good biological treatment, not
be present in the effluent at harmful concentrations.

     I do not mean to make light of the need for attention to control of
toxics.  Of course the public recreational waters, the desirable array of
fish and other aquatic organisms, and particularly public water supplies,
must be protected.  We only ask for addressing only real problems and
management of the significant risks.

     We believe it is possible to control and manage the use of municipal
systems for the treatment of many of these organic compounds through a
variet> of monitoring and control systems that would be developed for
                                    861

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each individual system.   Practically  speaking, each  system is unique, the
treatment may differ slightly,  the  mix of  other wastes will differ, the
dilution with other wastes will differ,  the most economic way to limit
the toxic may differ,  and the concentration of concerns  in the effluent
may well differ from location to location.  We feel  the  system that will
work best and which the  municipal managers will find most manageable and
economic will be for them to first  determine  the concentration of  the
candidate toxics present in the wastes as  discharged from the municipal
treatment plant.  Readily biodegradable toxics will  not  be found and the
concern for them can be  minimal. Any compound found above a concentra-
tion of concern can be controlled by  such  means as the management  of the
facility may choose.  The choice may  be to limit it  severely at the
source or limit the toxic just sufficient  to  equal the capacity of the
treatment plant to satisfactorily remove or some other means.

     Gentlemen, I do not wish to make light of a real problem.  We want
to be sure there is a real problem.  We must  use the most practical con-
trol system taking into  account effectiveness, economics, including the
utility of the product involved and manageability.   I do not believe we
will have trouble working such out  in a cooperative  effort.

Close

     I hope you have become more aware of  the value  of  joint treatment
and industrial interest in it.  Many  industrial plant executives recom-
mend their plant managers view the  municipal  wastewater  treatment  plant
that serves them as an extension of their  own manufacturing facility.
The same regard is recommended to be  held  for its  proper functioning and
its quality of effluent as there would be  for the  functioning  of  the
product manufacturing equipment and product  quality.

     The concern is illustrated by the story of one  paper  plant manager
who received a call from the local sewage  treatment  plant manager. This
industry made a great deal of colored paper.   The  treatment plant  person
said,  "You have dyed my whole treatment plant blue,  the  primaries  are
solid blue and there is blue all over, even in  the final tanks".   Of
course the industrial plant manager was concerned.   He  was  anxious to  do
the best thing to correct the situation to the  satisfaction of the treat-
ment colleague.  So he thought of the most accommodating thing he  could
do.  So he said, "We have a variety of colors out  here,  what  color would
like the plant to be?"

     That is a sick, sick joke of course.   I tell  it to emphasize  that we
are aware of the need to cooperate, to value, to  nurture our  colleagues
in the waste end of the business.  Please call  on us if you think we
could be of any help.
                                      862

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                                 TABLE 1

        NUMBER OF INDUSTRIAL PLANTS USING COMMUNITY SEWER SYSTEMS
    CITY

Atlanta
Chicago
Dallas
Salem
South San Francisco
TOTAL USERS

   100,000
 2,000,000
   230,000
    50,000
    20,000
   SIGNIFICANT
INDUSTRIAL USERS

       66
      350
      119
       18
       24
PERCENTAGE OF TOTAL
   FLOW       BOD
    15
     6
    10
     9
    13
19
50
39
47
                                 TABLE 2

      USE OF COMMUNITY WASTEWATER SYSTEMS BY INDUSTRIAL CATEGORIES
     INDUSTRY CATEGORY

Laundry detergents
Bar soap
Coffee
Edible oil refining
Fruit and vegetable canning
Paper converting
Steel rolling
Blast furnace
By-product cooling
Paper pulping
                      PERCENT OF INDUSTRIAL PLANTS
                       PRACTICING JOINT TREATMENT

                                   95
                                   99
                                  100
                                   92
                                    0
                                    0
                                    0
                                    5
                                 TABLE 3

       CAPITAL COST OF SEDIMENTATION FOR VARIOUS PLANT CAPACITIES*
                                       CAPITAL COST OF SEDIMENTATION
CAPACITY
   OF
 PLANT
  mgd

    1
   10
  100

*1971 costs
                   TOTAL
                 $ 42,000
                 $160,000
                 $920,000
               PER mgd
               CAPACITY
               42,000
               16,000
                9,200
         PERCENT
         OF 1 mgd
         CAPACITY
           38
           22
                                     863

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                                 TABLE  4

    CAPITAL COST OF DIFFUSED AIR SYSTEMS FOR ACTIVATED SLUDGE PLANTS
                                          CAPITAL  COST OF AIR SYSTEM
CAPACITY
   OF
 PLANT
  mgd

    1
   10
  100

*1971 costs
    TOTAL
    65,000
   320,000
 1,820,000
PER mgd
CAPACITY
   I

65,000
32,000
18,200
PERCENT
OF 1 mgd
CAPACITY
  49
  28
                                 TABLE 5

              CAPITAL COST OF TOTAL ACTIVATED SLUDGE PLANT*


                                                  CAPITAL COST
CAPACITY
   OF
 PLANT
  mgd

    1
   10
   50

*1967 costs
    TOTAL
   550,000
 3,200,000
11,000,000
PER mgd
CAPACITY
550,000
320,000
220,000
PERCENT
OF 1 mgd
CAPACITY
  58
  40
                                 TABLE 6

              LABOR COSTS FOR DIFFUSED AIR SYSTEM OPERATION
                                             LABOR MAN HOURS/YEAR
CAPACITY
   OF
 PLANT
  mgd

    1
   10
  100
    TOTAL
     1,480
     4,400
    16,100
 PER mgd
 CAPACITY
  1,480
    440
    161
 PERCENT
 OF 1 mgd
 CAPACITY
   30
   11
                                      864

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     COST-EFFECTIVENESS AND WATER QUALITY
     JUSTIFICATION FOR ADVANCED WASTEWATER
         TREATMENT (AWT) FACILITIES
               Robert J. Foxen
               Office of Water
      U.S.  Environmental Protection Agency
               Washington, D.C.
This paper has been reviewed in accordance with
the U.S. Environmental Protection Agency's peer
and administrative review policies and approved
for presentation and publication.
           Prepared for Presentation at:
        8th United States/Japan Conference
                        on
           Sewage Treatment Technology


                   October 1981
                 Washington, D.C.
                       865

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  COST-EFFECTIVENESS AND WATER QUALITY JUSTIFICATION FOR ADVANCED
  WASTEWATER TREATMENT (AWT)  FACILITIES

  Robert J.  Foxen
  Office of  Water
  U.S. Environmental Protection Agency
  Washington, D.C.

  I.   INTRODUCTION

        In 1977,  the "Vertex" draft  report(l)  prepared  by an EPA consultant
  concluded  that  many advanced wastewater treatment  (AWT) projects funded by
  the U.S. Environmental Protection  Agency (EPA)  were too costly and resulted
  in few, if any, water quality benefits.  AWT was basically defined as  any
  treatment  beyond secondary, which  is the minimum required by law.  The  Vertex
  report recommended that all further funding  of  AWT projects be stopped until
  questions  concerning the accuracy  of water quality analyses used to justify
  these projects  and the high project costs could be resolved.

        Spurred by this report, and  by a growing  concern about high cost waste-
  water treatment projects, the Appropriations Conference Committee of the U.S.
  Congress issued a directive in October 1978  which  required that  EPA grant  fund-
  ing for AWT projects with incremental capital costs for treatment beyond second-
  ary of greater  than $1.0 million may be provided only if the EPA Administrator
  "personally" determines that the project "will  definitely result in significant
  water quality and public health improvement."*  The House and Senate Appropri-
  ations Committees raised the incremental cost to $3.0 million for projects
  reviewed during fiscal year 1980.  For projects  with lower marginal costs,  AWT
  approval is given by Regional EPA  Administrators.

        To implement the requirements of this  directive, EPA issued Program  Re-
  quirements Memorandum (PRM) 79-7,  which outlined the  criteria for review of AWT
  projects.   PRM  79-7, which  requires that effluent  limitations for AWT  projects
  must be fully justified by  technically sound water quality analysses.    This
  will ensure that expenditures for  AWT processes will  result in significant water
  quality benefits; however,  this evaluation does not involve a cost-benefit
  analysis in which the "worth" of the benefits is weighed against the cost.
  Rather, given a specified water use goal, this  analysis seeks to assure that
  this goal will  be achieved  at minimum cost.
 *There have been various arguments that this directive is inconsistent with
  the Clean Water Act,  and Section 510 of the Act in particular which allows
  States to set water quality standards more stringent than the Federal minimum
  if they choose. The main question is whether the Act requires EPA to fund
  projects to meet these standards.
**These criteria include evaluation of water quality modeling, appropriateness
  of beneficial use classifications and water quality criteria, and a review of
  cost-effectiveness.  The State of Illinois (IEPA) sued EPA in December 1979,
  claiming that the AWT review violated the Clean Water Act. IEPA and EPA reached
  an-out-of court settlement on the case,  and EPA agreed to simplify some of the
  review requirements. As a result of this settlement, a final revised PRM will be
  issued and specify the review criteria to be used in future AWT reviews nationwide,

                                       866

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        An EPA Headquarters AWT Task Force has reviewed 68 AWT projects,
with capital costs for AWT of over $500 million. As of this writing, these
reviews have resulted in deferral of EPA funding for over $114 million worth
of unjustified AWT processes.  The findings in these reviews have created
intense controversy among affected cities, states, EPA regional offices,
and EPA Headquarters.

        This paper explains the rationale for the review criteria and
approach used in the AWT review at EPA Headquarters, provides an assessment
of removal capabilities and marginal costs of various AWT processes, and
describes case studies to indicate the results and implications of the
reviews conducted to date.  This paper also analyzes the accuracy of water
quality models used to justify AWT processes.
II.  REVIEW CRITERIA AND APPROACH

        A.  General Approach

        In typical water quality management planning studies, water quality
analysts established permit effluent limitations based on results of water
quality modeling studies, but without regard for the costs of unit processes
required by those limitations.  Engineers were then required to design
facilities to meet these limitations, regardless of the uncertainities in
the water quality analysis, or the costs of the unit processes that were
required.  The efforts of the water quality analyst and the design engineer
stopped at opposite ends of the pipe, with neither venturing into the sphere
of the other.

        Now this may be changing.  The justification for AWT projects
reviewed in Headquarters has basically involved balancing the uncertain-
ties in the water quality analyses against the marginal costs of the unit
processes being considered.  For unit processes with relatively high marginal
costs, more rigorous water quality analyses have been required than for unit
processes with lower marginal costs.  This approach allows more flexibility
in establishing permit limitations.*
*This approach in effect results in deferral of EPA funding in cases where
 it is not conclusively shown that these processes are needed.  It has been
 argued that this approach is inconsistent with the Clean Water Act, which
 requires that a "margin of safety" must be provided to compensate for
 uncertainties in the water quality analysis.  This may be a valid argument,
 although the definition of a "margin of safety" is subject to interpretation.
 Nevertheless, EPA made a policy decision to carry out the Congressional
 directive in this manner.
                                     867

-------
        B.   Evaluation of AWT Processes

             Nitrification and Tertiary Filtration Systems

        A summary of the types of advanced unit processes proposed and
approved by the Headquarters AWT Task Force appears on Table 1.   As shown
on this table, the most commonly proposed AWT processes were various nitri-
fication and tertiary filtration systems.  In nearly all cases where filtra-
tion was proposed, it was an add-on to nitrification rather than following
secondary treatment.

        Table 1 shows that nitrification was proposed in 55 cases and
approved in 51 cases.  On the other hand, tertiary filtration was proposed
in 48 cases and approved in only 21 cases.  Moreover, in many cases where
filtration was approved, approval was based on a consideration of the in-
flationary impacts that would result from delays for redesign following
elimination of filtration, rather than on technically sound water quality
analyses.  Thus, the number of cases where there was adequate water quality
analyses to justify filtration was less than the approvals indicated by
Table 1.

        The high approval rate for nitrification, and low approval rate for
filtration, resulted from two major reasons.  First, nitrification has a
relatively low marginal cost per unit of ultimate oxygen demand (UOD)*
removed, and removes a large percentage of UOD.  Filtration, on the other
hand, has a high marginal cost per unit of UOD removal, and removes only
a small percentage of UOD.**

        The second reason involves the predictive accuracy of water quality
models.  Generally, it is relatively easy to develop water quality models
accurate enough to determine whether the level of UOD removal provided by
nitrification is needed.  However, since filtration following nitrification
removes only a small percentage of UOD, inherent uncertainties in water
quality modeling make it more difficult to accurately predict whether
filtration is needed.  These issues are discussed in more detail in the
following sections.
 *UOD is defined as the total carbonaceous and nitrogenous oxygen demand.
  This may be estimated as follows:

             UOD, mg/1 = 1.5 x CBOD5, mg/1 + 4.57 x NH3~N, mg/1

             where CBOD5 = total carbonaceous BOD5 which includes SS.
**Filtration should obviously not be used to remove UOD after nitrification
  since little UOD remains in the wastewater.  Filtration could be used for
  suspended solids removal, total phosphorus removal, or for disinfection.
                                      868

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Cost Effectiveness

        A schematic diagram showing the removal capabilities of a typical
AWT facility providing nitrification followed by tertiary filtration
appears on Figure 1.  This figure shows that nitrification will reduce
ammonia concentration from about 20 mg/1 (following secondary treatment)
to an average of about 1 mg/1, and reduce CBOD5 concentrations from 30 mg/1
to about 8 mg/1.  Nitrification thus increases UOD removal from 67 percent
to 96 percent.  In addition, nitrification has the added benefit of reduc-
ing ammonia toxicity in the receiving water.

        Graphical presentations showing the marginal present worth cost
per mg/1 UOD removed for secondary, nitrification and tertiary filtration
appear on Figure 2.*  The figure shows that the marginal cost per mg/1 UOD
removed by nitrification is significantly less than for tertiary filtration,
and even less than the marginal cost per unit of UOD removed for secondary
treatment.  Specifically, Figure 2 shows that the marginal present worth
cost per mg/1 UOD removed by nitrification in a typical 10 MGD two stage
activated sludge system is about $24,000, as compared to a marginal cost
for secondary treatment of about $42,000 per mg/1 UOD removed. The marginal
cost for tertiary filtration following nitrification is over $1.0 million
per mg/1 UOD removed. Thus, the high approval rate for nitrification and
low rate for filtration in part resulted from differences in the marginal
costs and removal capabilities of these processes.

Predictive Accuracy of Water Quality Models

        These findings have significant implications for the water quality
analyses used to justify nitrification and tertiary filtration.  Since
nitrification has relatively low marginal costs and provides significant
reduction in UOD, simplified water quality analyses were often adequate
to justify this process.**  On the other hand, since filtration has a
high marginal cost for UOD removal and removes only a small amount of
UOD, more detailed water quality analyses, often involving a calibrated
and/or verified water quality model, were generally required.  More
accurate water quality models were also generally required to justify
filtration because it is more difficult to predict in-stream responses
to the relatively small UOD removals provided by filtration than for the
relatively large UOD removals provided by nitrification.
 *These estimates are based on the "typical" values shown on Figure 1,
  and would vary from plant to plant.  UOD removal efficiencies assume
  CBOD5 tests are used.
**New guidance for using simplified DO modeling techniques for justify-
  ing filtration was recently issued by EPA. These techniques require
  sensitivity analyses to justify filtration, and would require gather-
  ing calibration and/or verification data if the results of the sensi-
  tivity analysis do not conclusively establish that filtration is needed.


                                   869

-------
        The adequacy of simplified DO models and calibrated/verified DO
models for justifying AWT processes depended on the technical accuracy of
the model, and the marginal cost and removal capabilities of the process
in question.  In general, simplified approaches were adequate to justify
nitrification, but calibration and/or verification data were generally
required to justify tertiary filtration.   The case studies presented in
Section III provide several examples where simplified and calibrated DO
models were used to justify AWT processes, and explain the rationale for
accepting or rejecting these justifications.

        The most significant parameters affecting the predictive accuracy
of water quality DO models are the deoxygenation rates (Kd day-1) (i.e.,
including both day-1 carbonaceous and nitrogenous deoxygenation), and the
reaeration rates (Ka).  In simplified models, these rates are determined
based on literature values for similar water quality scenarios, from data
from nearby similar receiving streams, or, for Ka's, from empirical form-
ulas.  Since the rate constants used in these simplified approaches is not
based on site specific data, the accuracy of these models is limited.

        For calibrated and verified model, rate constants are determined
based on site specific in-stream measurements.  For example, carbonaceous
BOD (CBOD) decay rates would be determined by measuring CBOD decay in-stream.
However, the accuracy of these rates to predict future water quality impacts
of treatment levels may be questionable,  since Kd values are generally lower
at higher treatment levels, and the exact amount of the reduction cannot be
estimated with certainty.  This concern can be reduced if the water quality
analyst performs adequate sensitivity analyses within the range of typically
expected Kd values.

        Nitrogeneous oxygen demand (NOD)  decay may be determined by measur-
ing ammonia decay.  However, this approach may have to be modified in cases
where high algal populations exist, since ammonia depletion may actually
result in large part due to algal uptake, rather than oxidation.  In these
cases, the rate of nitrate increase may be a more accurate measure of
ammonia oxidation.

        The greatest amount of variability in most DO models involves Ka.
There are several empirical formulas available for estimating Ka (e.g.
O'Connor - Dobbins(2), Tsivoglou, et^a^.O), Owens, et^aju(4)), and suitabil-
ity of each varies depending on the characteristics of the receiving water.
For a typical low flow stream, Ka values may vary anywhere from 1.5 to 7.0
per day, base e.  It is not unusual to find Ka values as high as 20 per day
in some models.  On the other hand, typical Kd values resulting from dis-
charge of a well treated secondary or nitrified effluent into a low flow
stream generally range from about 0.3 to 0.6 per day, base e.  Thus, the
possible range for Ka is much greater than for Kd.

        Ka values in most water quality models reviewed  in EPA Headquarters
were determined from empirical formulas.  These Ka values were usually ad-
justed to fit observed DO data, where available, which is the generally


                                   870

-------
 correct  procedure  for  model  calibration.   However,  the  accuracy  of  this
 approach is  often  uncertain  since  the  initial  difference  between observed
 and predicted  DO may be  due  to  factors other than inaccuracies in the
 estimate of  Ka.

         The  most accurate means  for  determining Ka  is use of  the inert gas
 tracer'^) technique.   This approach  basically  involves  actual measurement
 of  gas transfer  in the receiving water in  question.  However, even  this
 approach has inherent  uncertainties, because of differences in conditions
 at  the time  of the gas tracer measurement  and  the prediction  conditions,
 and because  of uncertainties in  measurement techniques.   Thus, Ka rates
 estimated by gas tracer  techniques may also have to be  adjusted  during
 calibration.

         There are  also several other variables that may introduce addi-
 tional uncertainty into  water quality  models.  These include  measurement
 and prediction of  sediment oxygen demand,  effects of algal activity, and
 background DO concentrations.  These factors are not addressed in detail
 in  this  paper, but should be considered in determining  the accuracy of DO
 models,  and  the  expected improvements  from AWT.

         Despite  these  uncertainties, even  simplified models are  often
 adequate to  show whether nitrification is  needed, since the DO impacts
 of  the UOD removed by  nitrification are generally much  greater than the
 uncertainties in DO models.  However,  in the case of tertiary filtration
 following nitrification, the confidence limits of DO models (even with
 calibrated and verified  models)  often  exceeds  the predicted incremental
 DO  benefits  resulting  from providing tertiary  filtration  following nitri-
 fication.  Therefore,  water quality models are often not  accurate enough
 to  show  whether  tertiary filtration is  definitely required following nitri-
 fication to  meet a given DO criteria.

         The  effects of the uncertainties in DO models on  the ability to
 determine the need for filtration following nitrification are illustrated
 on  Figures 3, 4, and 5.  Figure  3 shows the expected DO improvement result-
 ing from providing filtration after nitrification, as a function of varying
 Ka  to Kd ratios, assuming a stream to  effluent dilution ratio of  1:1.  For
 example,  for Ka/Kd  = 6,  filtration following nitrification would  improve DO
 by  about  0.25 mg/1.

         Figure 4 shows estimated confidence bands for the DO deficit result-
 ing from discharge  of  a nitrified effluent.  These confidence limits were
 estimated  by assuming  that Ka has been  determined with  certainty  (i.e.,
 either via calibration or using  gas tracers), and that Kd could  vary by 25
 percent  to 75 percent.  Uncertainties  in estimating loadings sediment oxygen
 demand (SOD), algal effects, etc., were not considered.  Thus, this Figure
 represents a minimum amount of uncertainity associated with a calibrated
 DO model.  However, even given these conditions, Figure 5 shows  that for
 a Ka/Kd  =  6, the DO deficit resulting from discharge of a nitrified effluent
would be  1.0 mg/1,  but that it could range anywhere from  0.7 mg/1 to 1/3 mg/1
 due  to modeling uncertainties (i.e. uncertainties in Kd).
                                    871

-------
        To illustrate the effects of these uncertainties on determining
the need for tertiary filtration, Figure 5 shows that the DO improvement
resulting from providing tertiary filtration falls within the range of
confidence limits associated with the effects of a nitrified effluent.

        An example illustrates the effect of this problem.  Assuming a
Ka/Kd = 6 and a background DO of 5.8 mg/1, Figure 5 shows that discharge
of a nitrified effluent would depress DO by about 1.0 mg/1 to 4.8 mg/1.
This is below the DO criteria for warm water fisheries.  If filtration
were provided following nitrification (and Ka/Kd again = 6), the DO would
be depressed by about 0.7 mg/1, to about 5.1 mg/1.  This is above the DO
criteria.  However, if Kd is reduced to 0.3 per day, which is well within
the acceptable range for Kd's, DO resulting from discharge of a nitrified
effluent would only be depressed by about 0.6 mg/1, to about 5.2 mg/1.
This also is above the DO criteria.  Thus, it would not be possible to
determine whether tertiary filtration following nitrification would
definitely be needed to achieve DO criteria, or whether nitrification
alone would be adequate to achieve this DO level.  If other modeling
uncertainties are introduced, the ability to determine the need for
tertiary filtration would be limited even further.  These uncertainties
warrant particular attention in view of the high marginal costs associ-
ated with tertiary filtration for UOD control.

        There are two possible options for resolving this issue.  One is
to construct only the nitrification facilities, and then to monitor water
quality to determine whether more treatment is needed.  This approach has
the advantage of providing precise site-specific data for determining
treatment needs; the disadvantage is that delays while data is monitored
and analyzed would increase costs for additional treatment if needed, and
could prolong discharge of inadequately treated wastewater.

        The other option is to use post-audit water quality data from
similar nitrification facilities to refine modeling accuracy and more
precisely determine whether tertiary filtration is needed.  However,
while this approach could reduce modeling uncertainties, and preclude
project delays, it would still be limited in its predictive accuracy.

        C. Phosphorus Controls

        Phosphorus removal was proposed for 24 projects and approved for
16 (see Table 1).  In most cases where phosphorus removal was approved,
the projects discharged either into the Great Lakes or the Chesapeake Bay,
where there had been extensive studies of the potential impacts of phos-
phorus on the trophic state of the receiving waters.*  For dischargers
into other water bodies, adequate water quality analyses existed in only
a few cases.  However, where phosphorus removal was not justified, it was
recommended that the plant be built to account for the possibility that
phosphorus removal may be required in the future, in order to avoid
possible retrofit problems.
*These studies have resulted in an international agreement between the U.S.
 and Canada which limits phosphorus discharges into the Great Lakes and their
 tributaries to 1.0 mg/1 for all municipal discharges greater than 1 MGD.
                                   872

-------
        The primary reason for the lack of adequate water quality justi-
fication for phosphorus removal is the inherent complexity of accurately
modeling phosphorus-chlorophyll relationships.  Modeling the effects of
phosphorus requires an assessment of non-point loadings, and bio-assay
studies to identify the limiting nutrient.  Other complicating factors,
such as predicting reaction rates, bio-feedback, turbidity, light pene-
tration, etc., also make this analysis relatively complex.

        Because of the complexities mentioned above, EPA Headquarters has
re-evaluated the criteria for approval of phosphorus removal.  This re-
evaluation considered the following issues:

        0  modeling of phosphorus-chlorophyll relationships is
           difficult, and could not be done in many cases due to
           limitations in man-power, technical expertise, etc.

        0  potential adverse impacts from not controlling phosphorus
           could be severe and difficult to reverse

        0  capital costs for phosphorus control are relatively low, at
           least down to about the 1.0 mg/1 level. (Clarification would
           generally not be capable of meeting effluent limits below
           1.0 mg/1.  Thus, more stringent limits would require some
           type of filtration system or other costly processes)

        Based on these considerations, simplified procedures are being
developed for justifying phosphorus removal.*  Criteria for justification
using simplified procedures include:

        0  demonstrating that there is an existing or potential (marginal)
           phosphorus-related water quality problem

        0  if the water quality problem is only marginal, demonstrating
           (supporting data) that phosphorus  loadings will increase
           significantly

        0  demonstrating that phosphorus is the limiting nutrient

        0  demonstrating that point sources contribute a significant
           portion of total phosphorus loading

        0  demonstrating that phosphorus controls will not result  in
           significant cost impacts (both capital and operating costs)

        These criteria will be applied to future projects where phosphorus
removal is proposed, and may also be applied  to projects where EPA funding
for phosphorus removal has previously been deferred.
*The decision to allow simplified approaches to evaluate phosphorus removal
 evolved during the review process.  Specific criteria and procedures  to be
 used in this regard will be included in the revised PRM, to be issued
 shortly, and other subsequent water quality guidance.

                                    873

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        D.  Separate Stage Denitrification

        Separate stage denitrification was proposed in only two cases, and
was not justified in either case.  Like phosphorus, the impact of nitrates
on a receiving waters' trophic state is relatively difficult to model.  Even
predicting future nitrate concentrations may be difficult since denitrifi-
cation could occur in-stream.  However, unlike phosphorus removal, both
capital and operating costs for separate stage denitrification with methanol
are high.*  Therefore, justification for nitrogen control would have to be
more rigorous than for phosphorus controls.  This justification may involve
gathering field data to calibrate the results of model predicted in-stream
reactions, as well as nutrient limiting studies, and an assessment of non-
point sources.

III.  CASE HISTORIES

      Manasquan, New Jersey

        The Manasquan project provides a good example of the use 01 simpli-
fied modeling procedures for justifying effluent limitations.  The proposed
Manasquan project is a new 8.1 MGD oxidation ditch unit, using the Carrousel
system.  The project involved regionalizing several small package plants
located further upstream.  The project had originally included tertiary
filtration following the Carrousel unit, but the Regional EPA Office in
New York determined that the filters were not justified.

        The facility would discharge to the Manasquan River Estuary, several
miles upstream from the Atlantic Ocean.  The river is designated for contact
recreation, fishing and shellfish harvesting.  Shellfish harvesting had been
discontinued due to pollution from upstream package plants.  The DO standard
for the river is 5.0 mg/1.

        The effluent limitations included a 10 mg/1 limitation for CBOD5, and
a 2.0 mg/1 seasonal limitation for ammonia, which applied from May through
October.  A simplified desk-top water quality (estuary) model was used by the
EPA Regional Office to verify the need for these effluent limitations.  Since
no discharge existed near the proposed outfall, the Kd rate constants used in
the model had to be based on literature values.  To account for inherent in-
accuracies in using these literature values, the Region performed sensitivity
analyses to indicate the in-stream DO responses under various possible scenar-
ios.  Results of this analysis showed that the allowable UOD loading ranged
between 400 Ibs/day and 2,000 Ibs/day, depending on which rate constants
were used.  The Regions' "best" estimate of allowable UOD loading was 1,200
Ibs/day.  If secondary treatment were provided, the effluent UOD loading
would be 12,700 Ibs/day, or more than six times the maximum estimated allow-
able concentration.  If tertiary filters and nitrification were provided,
effluent UOD loading would be 750 Ibs/day.  If the Carrousel system were
used without filtration, the UOD loading would be about 1,600 Ibs/day.
*Where methanol is not used for denitrifIcation, partial denitrification
 ( ~ 80% removal) in single sludge in extended aeration or Carrousel
 systems would not be high.

                                   874

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        The marginal present worth costs per mg/1 UOD removal for second-
ary, nitrification and tertiary filtration for this project are shown in
Figure 6.  Figure 6 shows that the marginal costs per mg/1 UOD removed for
secondary and nitrification are about $76,000 and $13,000, respectively. The
total cost for nitrification was estimated to be only about $1.0 million.
In contrast, the marginal cost per mg/1 UOD removed for filtration would be
over $1.0 million.  The capital cost for filtration would be about $3.0
million.  Because the simplified analysis showed it is very likely that
treatment beyond secondary is needed, and because the marginal cost for
nitrification is relatively small, the Region concluded that the Carrousel
unit is justified.  Although the UOD loading from the Carrousel process
without filtration would be slightly greater than the "best estimate"
allowable UOD loading, the Region concluded that the filters were not
justified because of their relatively high marginal cost, and because of
the inaccuracies inherent in the simplified mode.  The Headquarters AWT
Task Force concurred with these conclusions.

      Rochester, New Hampshire

        The Rochester project provides an example where both nitrification
and filtration were justified.

        The proposed project involves construction of a new 4 MGD facility,
using two-stage nitrification, followed by dual media tertiary filtration.
The city currently discharges raw sewage.  The nitrification system would
include a roughing trickling filter, followed by separate stage activated
sludge.

        The receiving water is the Cocheco River.  The designated uses
(recently upgraded) of the river include swimming and cold water fishery.
Large oyster beds exist downstream, but these have been closed due largely
to pollution from Rochester.  Thus, one potential benefit from the project
would be to re-open the oyster beds.  In addition, the State is implementing
plans, including installing fish ladders, to establish salmon spawning.

        The critical design flow (7 day once in 10 year low-flow) in the
river is about 2.2 cubic feet per second (CFS).  The river is currently
highly polluted due to the Rochester discharge.  The water quality standards
require a DO of 6.0 mg/1 or 75 percent of saturation, whichever is greater.

        The design effluent CBOD5 and ammonia limitations were 5.0 mg/1 and
1.0 mg/1, respectively.  A calibrated (but not verified) DO model was used
to determine these limitations.

        In its original final AWT report, the Headquarters AWT Task Force
concluded that the water quality analyses did not justify the need for the
dual media filters.  This conclusion was reached because the proposed ter-
tiary filtration system had a cost of about $1.3 million, and would provide
only slight additional reduction in UOD.  Similarly to other projects, the
marginal cost per mg/1 UOD removed for filtration vis-a-vis secondary treat-
                                  875

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ment and nitrification was very high.  In addition, since the city currently
discharges raw sewage, there were uncertainties in the water quality analyses
because of inherent difficulties in estimating rate coefficients under future
conditions with highly treated effluents.

       Following a review of this report, the State submitted new information
supporting the need for tertiary filtration.  This information provided lower
cost estimates which showed that there would be negligible savings if the
filters were eliminated.  These lower costs resulted from changing the filtra-
tion system from dual media to sand, which reduced the capital cost of the
filters from about $1.3 million to about $550,000.

       In addition, the State noted that additional chlorine would be required
without filters because of higher suspended solids concentrations.  This would
necessitate dechlorination, further reducing potential savings from eliminating
the filters.  Using these assumptions, the present worth cost of retaining the
filters exceeded the cost without filters by only about $95,000.

       The Task Force also considered the possibility that further water q"ali-
ty analyses would justify filtration.  Despite some questions and shortcomings
concerning the existing water quality modeling efforts, the overall work was
reasonable.  The water quality model was properly calibrated, and showed that
filtration is needed.  Thus, it was not unlikely that verification of the
existing model might also show that filtration is required.

       Finally, more specific evidence was provided showing steps being taken
by the State to establish a salmon fishery, including spawning grounds, below
the discharge point.  The State also planned to re-open oyster beds that are
now closed due to pollution from Rochester.  Although not demonstrated (and
difficult to prove), the reduced suspended solids loading with the filters
might enhance these uses. In view of these considerations, it was considered
likely that filters would prove to be justified if additional water quality
studies were conducted.

       Based on the above considerations, the Task Force concluded that sand
filters were justified for this project.


IV.  CONCLUSIONS

       A rigorous review of water quality related effluent limitations should
occur prior to facility planning.  Such review should provide for flexibility
in establishing effluent limitations by allowing the marginal costs for AWT
processes and uncertainties in water quality analyses to be weighed before
final effluent limits are set.  Generally, water quality analyses for AWT
processes with higher marginal costs should be more rigorous than analyses
for processes with lower marginal costs.
                                     876

-------
      Nitrification and tertiary filtration were the most commonly pro-
posed AWT processes.  Nitrification was justified in most cases because
it has a relatively low marginal cost per unit of UOD removed,  and because
water quality models are usually accurate enough to determine whether this
level of treatment is needed.  Tertiary filtration was not justified in
most cases because it has a relatively high marginal cost per unit of UOD
removed and because inherent uncertainties in water quality modeling make
it difficult to accurately predict whether the level of treatment provided
by filtration following nitrification is needed to meet water quality
standards.

      Water quality analyses for justifying phosphorus or nitrogen removal
are complex.  Since phosphorus removal is generally relatively inexpensive,
simplified water quality analyses are often adequate.  Since nitrogen
removal is more costly to remove, more sophisticated analyses,  possibly
involving a calibrated model, may be required.
REFERENCES

1.  Horowitz, J. and Bazel, L.,  "An Analyses of Planning for Advanced
    Wastewater Treatment (AWT)",  U.S. EPA, Office of Planning and
    Evaluation.  Final Report,  Contract No. 68-01-4338,  Washington,
    B.C., July 1977.

2.  O'Connor, D. J., and Dobbins, W. E., "American Society of Civil
    Engineers Transactions, 123,  641 (1958).

3.  Tsivoglou, E. C., e£ aJN,  "Tracer Measurements of Stream Reaeration
    II, Field Studies ""journal Water Pollution Control  Federation,
    40, 285 (1968)

4.  Owens, M., et al., "Some Reaeration Studies in Streams", Inter-
    national JournaT of Air and Water Pollution, 8, 469  (1964).
                                    877

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                                              FIGURE 1
                       Two Stage  Nitrification  --  Typical  Removal  Efficiencies
Raw Sewac
CBOD5 (mg/1) 200
(% Removal)
00
00
NH3-N (mg/1) 25
(% Removal )
UOD (mg/1)* 414
(% Removal)
je — - Primary —
130
35%

25
0%
309
25%
— Secondary —
30
85%

20
20%
136
67%
-— Nitrification —
8
96%

1
96%
17
96%
Tertiary
— Filtration
4
98%

1
96%
12
97%
Cost ($ million)**
   * UOD - 1.5 (CBOD5) + 4.57 (NII3-N)
  ** Based on 10 MGD facility
11.7
2.87
3.5

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                            FIGURE 2

                 MARGINAL COSTS FOR TYPICAL

          TWO-STAGE  10 MGD NITRIFICATION FACILITY
1200
1100
1000
 100
  75
  50
  25
                                                   $1,100,000
                                          TERTIARY
                                          FILTRATION-
               $42,000
               SECONDARY
                                             $24,000
                                          NITRIFICATION
                                                I	
             ,97
              20
                         40         60   67

                          % "UOD REMOVED
80
         96
                               879

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                                                              FIGURE  3
00
00
o
                  (Ka/Kd)
                             12



                             10



                              8
                              2



                              0
                                        DO Improvement from Tertiary  Filtration
 Nitrification
                                        Filtration'
                                            0.5
1          1.5



      DO (mg/1)
2.5

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                                                              FIGURE 4
                                    Confidence  of DO Models
00
00
                (Ka/Kd)
12



10



 8



 6



 4



 2



 0
\   Nitrification

   x
                                           0.5
                                       1.5          2


                                      DO (mg/1)
                                   2.5

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                                                             FIGURE 5
                                   Need  for Tertiary  Filtration
00
00
ro
                 (Ka/Kcl)
12




10




 8




 6




 4




 2




 0
                                         Filtration
                                           0.5
                                        1.5
2.5
                                                                  DO (mg/1)

-------
                            FIGURE 6




                OXIDATION  DITCH  -  MAMASQUAN,  N. J.



                    8.0 MGD  - REMOVAL  COSTS
 1,175





 1,150





 1,125





 1,100





 1,075





1,050





1,025





1,000
  100





   75





   5C





   25






   0
  $75.899
SECONDARY
                                            $1,140,000
                                  FILTRATION
                                 $13,210
                               NITRIFJC/VTION
                 20          40           60



                          % UOD REMOVAL
                            67
eo
96 100
                                883

-------
PRXESS
Nitrification
Tertiary Filtration
Phosphorus Removal
Denitrification
                                    TABLE I
                         ADVANCED TREATMENT PROCESSES
                             PROPOSED AND APPROVED
 NUMBER
PROPOSED
55
48
22
2
  NUMBER
APPROVED
51
21
14
0
                            884

-------
          EFFECTS OF MULTIPLE DIGESTION ON SLUDGE
      Wilbur N. Torpey, Consultant, New York,  New York
       John F. Andrews, University of Houston, Texas
James V. Basilico, U.S. EPA,  Office of Research & Development,
                      Washington, D.C.
        This paper has been reviewed in accordance with
        the U.S. Environmental  Protection Agency's peer
        and administrative review policies and approved
        for presentation and publication.
                  Prepared for Presentation at:
               8th United States/Japan Conference
                              on
                  Sewage Treatment Technology

                          October 1981
                        Washington, D.C.
                             885

-------
EFFECTS OF MULTIPLE DIGESTION ON SLUDGE

Wilbur N. Torpey, Consultant, New York, New York
John F. Andrews, University of Houston, Texas
James V. Basilico, EPA, Office of Research & Development,
  Washington, D.C.
ABSTRACT

     This paper presents the development and application of the mesophilic-
thermophilic process that has been pioneered by the City of New York at
their Rockaway wastewater treatment plant.  This was accomplished by the
use of a two-stage digestion system, consisting of a mesophilic stage fol-
lowed by a thermophilic stage.  A part of the thermophilically digested
sludge was also recycled through the aeration tanks to obtain additional
destruction of organic solids.  The advantages of the thermophilic process
are retained without the disadvantages.   Results  Indicate  that  the physical
characteristics of meso-thermo  digested  sludge  are  changed to the extent
that the economics of dewatering are significantly  improved.  Moreover,
has met the time-temperature  requirements for pathogen  destruction.

INTRODUCTION
                                       \
     Coastal cities , including  the City  of New York, being under  Federal
mandate to cease ocean dumping of sludge derived from the  treatment of
wastewater, have been engaged in studies of land-based disposal alterna-
tives for the past couple of years.  Many of these studies were aimed at
determining the optimal methods of dewatering digested sludge as well as
the subsequent steps for ultimate land disposal.

     In studying the work performed by Kraus in 1946(1), it was noted that
exposing volatile solids to both anaerobic and aerobic environments
resulted in improved destruction of volatile solids.  This led to  the idea
that alternate exposure of volatile solids to different environments could
substantially reduce the quantity of sludge for ultimate disposal.  The
work of Kraus when considered in conjunction with the work of Buhr and
Andrews(2) on the thermophilic digestion process led to the concept of the
new process proposed herein.  The idea was advanced that,  as a fundamental
and first priority part of the management program, present plant facilities
should be tested for use in reducing to a minimum the rate of sludge pro-
duction from an activated sludge plant, both as to volume  and volatile
matter.  The rationale would be based on the exploitation  of biochemical
mechanisms; namely,  that improved destruction of volatile solids could be
                                    886

-------
obtained by exposing the mesophilically digested solids to the enzyme sys-
tems of thermophilic digestion and activated sludge.  Advantage gained in
this investigation would be reflected commensurately in the economics of
all the sludge dewatering and post-dewatering processes that were pre-
viously studied.

Present Practice of Thermophilic Anaerobic Digestion

     Thermophilic anaerobic digestion is very similar to mesophilic
anaerobic digestion except the temperature at which it operates is
120-130° F instead of 90-100° F.  It thus takes advantage of the fact that
biochemical reaction rates can be increased by increasing temperature.  It
is only natural, therefore, that conversion of existing mesophilic
digesters to thermophilic operation should be considered as a low-cost
technique for increasing the sludge processing capability of wastewater
treatment plants.  Full-scale studies by the Metropolitan Sanitary District
of Greater Chicago, (3), the Ontario Ministry of the Environment, Canada,
(4) and in Moscow, U.S.S.R. (5) have indicated that the sludge processed
per unit volume of digester capacity could be doubled by converting from
mesophilic to thermophilic operation.

     Besides its increased sludge processing capability, thermophilic
operation also offers two other significant advantages over mesophilic
operation:  improved sludge dewatering characteristics and increased
destruction of pathogens.

     Garber's work on the vacuum filtration of thermophilic sludge at the
Hyperion plant in Los Angeles provides an example of how sludge dewatering
can be improved by the thermophilic digestion.(6)  He reported a 270 per-
cent increase in vacuum filter yields with a 48 percent decrease in coagu-
lant dosage for thermophilic, compared to mesophilic sludge.  Improved
solids-liquid separation is important in land application of sludge by
decreasing the quantity of wet sludge for disposal and thus lowering
transportation costs.

     An example of the increased destruction of pathogens by thermophilic
digestion is given by Popova and Bolotina (5) in their report of the practice
of thermophilic digestion in Moscow, U.S.S.R.  They state:  "The most
essential advantage of this process is the sanitary quality of the
thermophilic sludge.  According to the sanitary officials of the health
department, viable eggs of helminths are absent from such a sludge."  This
improvement in sanitary quality is of special significance in light of the
current trend toward land disposal of digested sludge.

Development of the Mesophilic-Thermophilic Process

     The Rockaway wastewater treatment plant, having a connected population
of 100,000, was chosen for a full-scale test.  The plant employs conven-
tional facilities for the activated sludge process, and the sludge generated
undergoes mixed primary and secondary sludge thickening prior to mesophilic
                                    887

-------
digestion.  The digested sludge is transported to sea.  As presently oper-
ated, the primary tanks provide a detention of about 2 hours; the aeration
tanks provide 3.3 hours, with step feed provisions; and the final tanks pro-
vide 3 to 5 hours of settling depending on the number in use.  Two 45-ft.
diameter thickening tanks are used for mixed sludge thickening and the
mesophilic digestion is accomplished in a 1 cu.ft./capita tank.

     For purposes of this test, the following steps were taken:  (1) an
additional 1 cu.ft./capita digestion tank was placed in service to receive
the overflow sludge from the mesophilic digester and its contents heated up
to 120-122° F, the lower limit of the thermophilic digestion range;
(2) piping was installed to carry a portion of the overflow from the ther-
mophilic digester directly to a single 45-ft. diameter tank to be employed
as a rethickening and elutriating tank; (3) piping was installed to conduct
the remainder of the flow from the thermophilic digester into the primary
effluent and thereby directly into the aerator of the secondary treatment
system, and (4) city water was conducted to the elutriation tank.  The ele-
ments of this new method of sludge processing therefore involved:  (1) sub-
jecting the mesophilically digested sludge to subsequent thermophilic
digestion; (2) recirculating part of the sludge leaving the thermophilic
digester directly to and through the secondary treatment system; and
(3) subjecting the other part of the sludge leaving the thermophilic
digester to a rethickening and elutriation step.

     The thermophilic digester was placed in operation in September 1979.
On January 15, 1980, the necessary piping additions were completed and on
that date the recirculation and rethickening elements of the new method
were brought into service.

Effect of Recirculation on Process Performance

     At the time the full-scale test was started, the activated sludge had
a rather low sludge density index of 0.6 to 0.7.  Microscopic examination
revealed a significant population of bacterial filaments along with
colonies of stalk ciliates and some rotifers.  After the digested sludge
recirculation was in practice for only a few days, the sludge density index
was found to have risen to 1.0 and the bacterial filaments were found to
have diminished substantially.  During the entire course of the following
test, the sludge density index continued to lie in the stable range of 1.0
to 1.4.

     Since the flow received at the plant approximates 200 gals/capita/day,
the influent wastewater strength is low, averaging about 100 rag/leach of sus-
pended solids and BOD5.  Prior to the test, the suspended solids and BOD5
in the effluent averaged about 12 and 12 mg/1, respectively.  The monthly
treatment results for the prior period July to December 1979 are presented
in Table I, as well as the treatment results during the course of this test
run from January 15 through May 29, 1980, for comparative purposes.  It  can
be seen from these data that no significant effect on treatment efficiency
was experienced as a result of the continuous recirculation of digested

-------
               Table I

               Rockaway Wastewater Treatment Plant (WTP) Treatment Efficiency  -  July  1979 to  May 1980
oo
oo
Month
July
August
September
October
November
December
Average Pre-Test
January (15-31)
February
March
April
May
Average Test
Flow
(M.G.D.)
22
22
23
25
22
21

21
19
23
27
29

Influent Wastewater
SS BOD5
(mg/1)
88
83
93
116
140
125
107
86
86
106
94
94
95
111
117
90
103
112
124
109
91
85
57
49
43
65
Final Effluent
SS BOD5
(mg/D
12
16
12
18
13
10
14
8
9
13
15
15
12
13
12
10
12
11
11
12
8
8
8
6
6
7

-------
sludge through the aeration system, at least during the first three
months.  In the latter two months, suspended solids in the effluent did
increase by about 3 mg/1 with a substantial increase in flow rate from
about 20 M.G.D. to 27-29 M.G.D.

Nutrient Removal

     In order to further evaluate whether the recirculation of digested
sludge through the secondary system had an adverse effect on effluent
quality, the data pertaining to the parameters nitrogen and phosphorus
shown in Table II.  The effluent values are of special interest since the
raw wastewater samples did not contain the recirculating flow.  Inspection
of the data for the two periods, pre-test and test, shows that the
total average inorganic N was 8.2 ppm vs. 9.6 ppm, respectively.  Although
the individual months vary based on the period averages, inorganic nitrogen
shows an increase of 1.4 ppm in the effluent during the test period over
the pre-test period.  On the other hand, the organic nitrogen showed a
decrease of 4.3 ppm.  Phosphorous concentrations in the effluent remained
essentially unaffected when comparing the two periods.  It would appear
that the digested sludge recirculation had a rather minor effect on the
effluent quality with respect to the nutrients nitrogen and phosphorus.

Heavy Metals Removal

     The results of the monthly metal analyses of composite influent and
effluent samples for the pre-test period July to December 1979, and for the
test period January to May 1980, are presented in Table III.  Comparing the
overall averages of these test periods and focusing on the two metals that
have been demonstrated to be able to exert a major effect on human physi-
ology, namely cadmium and mercury, there does not seem to be a significant
difference between the removals.  In fact, the activated sludge process
does not appear capable of reducing appreciably the very low concentration
of either of these metals.  It should also be pointed out that mass balance
studies of the metal data, except cadmium and mercury, have been generally
good.  Because of the low concentrations of the metals cadmium and
mercury, and the sensitivity of the testing procedure, the mass balances
were not good.  As to the other heavy metals, comparative inspection of the
data presented indicates some variable effects of treatment during individ-
ual months with the overall averages not significantly changed for the sub-
ject periods.

Effect of Recirculation on Oxygen Requirements

     As to the influence of digested sludge recirculation on the dissolved
oxygen requirements, there was no change in air compressor output over the
course of the test.  Unfortunately, the air compressor was operating at a
level to produce more than adequate dissolved oxygen and its rate could not
be lowered before or during the test to specifically attempt to evaluate
any demand changes.  A calculated estimate, based on the fact that meso-
digestion (without the benefit of subsequent thermo-digestion) destroys 90%
                                   890

-------
Table II '
Rockaway UTP Nutrient Concentrations Influent & Effluent
Month
July 78
August
September
October
November
oo December
i— »
Average
Pre-Test
January 80
February
March
April
May
Aver. Test
Feb. to May
N (mg/1)
NH -N Org.-N N03 N02
Infl.
Effl.
Infl.
Effl.
Infl.
Effl.
Infl.
Effl.
Infl.
Effl.
Infl.
Effl.
Infl.
Effl.
Infl.
Effl.
Infl.
Effl.
Infl.
Effl.
Infl.
Effl.
Infl.
Effl.
Infl.
Effl.
13.0
1.6
7.8
1.8
_ *
_ *
7.8
0.6
12.5
9.4
10.4
9.2
10.3
4.5
9.4
0.6
11.6
2.6
9.6
3.0
7.0
1.0
9.4
2.4
9.4
2.3
5.8
2.9
8.4
3.0
10.5
9.6
8.4
3.0
15.1
8.6
16.0
14.8
10.8
7.0
9.8
3.0
10.6
2.2
15.6
4.2
8.6
3.2
9.2
1.2
11.0
2.7
0
7.0
2.3
5.9
_ *
_ *
0
5.2
0.1
0.4
0.3
0.2
0.5
3.7
0.2
6.3
0.3
8.2
0.8
10.0
0.3
5.6
0.3
5.4
0.4
7.3
0
2.0
.5
.9
_ *
_ *
0
0.2
0.2
0.5
0
0
0
0.5
0.1
0
0
0
0
0.2
0
0
0
0
0
0
Total
Inorg. N
13.0
10.6
10.1
9.7
-
7.8
6.0
12.8
10.3
10.7
9.4
10.8
8.2
9.6
6.9
11.9
10.8
10.4
13.2
7.3
9.8
9.7
7.8
9.8
9.6
P
Total
2.3
1.8
2.5
2.1
2.5
2.1
2.0
1.2
2.7
1.6
1.8
1.6
2.4
1.7
2.7
1.8
2.8
1.7
3.9
2.0
2.9
2.4
2.5
2.0
3.0
2.0
(mg/1)
Ortho
1.7
1.8
1.8
1.4
1.1
1.7
1.4
1.2
1.9
1.2
3.5
3.0
1.9
1.7
1.6 Transition
1.5 Month
1.8
1.4
1.9
0.7
1.2
1.1
1.3
1.6
1.6
1.2
 * Analytical  results  deleted

-------
      Table III
      Rockaway WTP Metal Data in (mg/1)
00

Cu

Cr

Ni

Zn

Pb

Fe

Cd

Ca

Mg

Hg


Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
July
.11
.07
.001
.006
.07
.04
.11
.14
.017
.006
.8
.2
.0001
.0001
41.0
36.0
94.0
98.0
.0010
.0006 '
August
.11
.05
.020
.015
.02
.02
.26
.35
.024
.006
.9
1.0
.0001
.0001
40.0
48.0
107.0
112.0
.0007
.0006
1979
September
.13
—
.012
.008
.02
.01
.23
.16
.110
.006
1.5 1
.7 1
.0004
.0002
41.0 29
32.0 41
102.0 94
105.0 101
.0007
.0002
October
.13
.03
.009
.002
.01
.01
.09
.17
.014
.008
.5
.2
.0001
.0001
.0
.0
.0
.0
.0005
.0005
November
.16
.06
.011
—
.02
.02
.12
.15
.027
.020
1.6
2.0
.0010
.0015
19.0
20.0
85.0
88.0
.0026
.0028
December
.11
.05
.034
.007
.01
.02
.08
.08
.023
.007
1.1
.1
.0008
.0006
13.0
15.0
76.0
77.0
.0005
-.0009
Average
.12
.05
.014
.008
.03
.02
.15
.17
.036
.009
1.2
.9
.0004
.0004
30.0
32.0
93.0
97.0
.0010
.0009

-------
Table III (Continued)
Rockaway WTP Metal Data in  (mg/1)

Cu

Cr

Ni

Zn

00
S pb
Fe

Cd

Ca

Mg
Hg

Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
January
.095
.22
.0007
.0012
.015
.018
.066
.070
.014
.030
.57
1.00
.0018
.0005
14.0
14.0
70.0
72.0
.0009
.0011
February
.080
.0035
.0012
.001
.009
.021
.093
.086
.049
.0024
.65
.16
.0005
.0004
16.0
17.0
60.0
64.0
.0005
.0003
1980
March
.110
.0400
.0038
.003
.0042'
.0024
.090
.065
.0089
.0016
.55
.21
.0011
.0009
14.0
15.0
58.0
59.0
.0009
.0002
April
_____
	
.010
.005
.0068
.014
.21
.079
.0088
.0034
.84
.13
.0046
.0029
13.0
14.0
54.0
55.0
.0003
.0005
May
.075
.0380
.0038
.001
.0086
.011
.085
.10
.010
.0064
.83
.46
.0011
.0017
23.0
21.0
59.0
62.0
.0003
.0004
Average
February to May
.088
.027
.0047
.002
.0072
.012
.12
.082
.018
.0035
.72
.24
.0018
.0015
16.0
17.0
58.0
60.0
.0005
.0004

-------
 of  BOD5,  indicates  that  the BODs of  the part of  the digested sludge
 continuously recirculated would add  less than 5% to the oxygen demand of
 the primary effluent.

 Operating Results

     As was pointed out previously,  a 1 cu. ft./capita tank was placed in
 service as a thermo-digester at about 121° F.  Its contents overflowed by
 gravity to both the primary effluent and to a 45-ft. diameter rethickening
 and elutriating tank where about 3:1 of city water was added to the
 influent sludge.  The rethickened underflow sludge was pumped by a duplex
 plunger pump, actuated by time clock, to spare empty digesters where its
 volumetric rate was measured by filling the tanks during the months of
 March and April.  Very importantly,  such procedures did not involve the use
 of any manpower except for periodically blowing back clogged lines.

     The data obtained are presented in Table IV.  Here it can be seen that
 the volatile matter leaving the meso-digester averaged 9,000 Ibs./day, thus
 effecting a reduction of 16,200-9,000 = 7,200 Ibs./day.  The thermo-
 digester accounted  for a further reduction of 9,000-7,200 = 1,800 Ibs./
 day.  It should be pointed out that  such reductions were being effected on
 the combination of raw primary solids, activated sludge solids and the
 recirculating solids that had been previously subjected to meso- and thermo-
 digestion.

      The conventional activated sludge treatment units are represented
 in Figure 1.  Since the economics of sludge disposal is fundamentally a
 function of the amount of volatile material to be disposed of, only the
 rates of production of volatile matter (V.M.) are discussed.  In an over-
 all sense, it can be seen that the reduction of volatile matter by the
 meso-digester of 7,200 Ibs./day, added to  1,800 Ibs./day by the thermo-
 digester, results in a total of 9,000 Ibs./day.  Additionally the aerator
 destroyed 2,000 Ibs. V.M./day for a  total  reduction of 11,000 Ibs. V.M./day.
 Since the treatment system was removing a  total of 12,900 Ibs. V.M./day, the
 net amount requiring disposal was reduced  to 1,900 Ibs. V.M./day.  Previous
 data show that the average amount of volatile matter carried to sea in the
 period just prior to this work (thermo-digestion was being started in August
 and September 1979) was 5,700 Ibs.   Thus,  the amount of volatile solids was
 reduced by 5,700 - 1,900 = 2/3.  Volume reduction was in the same proportion;
               5,700
 that is, 4,800 cu. ft./day to 1,650  cu. ft./day, or about 2/3.
     The daily amount of gas generated during the entire course of the
thermo-digestion is shown in Table V.  Based on the averages for the period
February to May, the meso-digester accounted for an 83,900 cu.ft./day rate,
slightly less than the comparable preceding period without digested sludge
recirculation through the aerator.  The gas generated by the thermo-
digester increased from an average of 7,000 cu.ft./day to 14,000 cu.ft./day
                                    894

-------
Table IV
Rockaway WTP Amount and Concentration of Solids Passing Through System!



00
VO
en

Month Flow
1980 MGD
Jan. 21
Feb . 19
Mar. 23
April 27
May 29
Average
Feb. to 25
May
#VSS
Capt. @
75% V.M.
10400
9500
14800
13400
14200
12900

Raw
Thick
Pump
Cu.ft./Day
5900
7300
8400
6500
8500
7700

%
Raw
Thick
3.9
3.6
3.3
3.5
3.0
3.4

Cone.
V.M.
Meso
Dig.
1.6
1.8
1.7
1.9
2.0
1.9


Thermo
Dig.
1.1
1.3
1.5
1.5
1.6
1.5

#V.M.
From
Thick.
14500
16500
17500
14500
16200
16200

#V.M./Day Leaving
Meso
Dig.
6000
8200
8900
8000
10800
9000

Thermo
Dig.
4100
5900
7800
6400
8600
7200

Rethickener &
Elutriator
Under Over
Flow Flow
-
-
1800 2
2000 2
1900

-
-
500
400
600
500

Note - (1) Calc. of V.M. inventory in digesters after February show the inventory change does not
           significantly influence the data.

       (2) Measured volume March 1600 cu. ft/day x 63 x 1.8% = 1800 # V.M./day
                           April 1700 cu. ft/day x 63 x 1.9% = 2000 // V.M./day

-------
00
VO
CM
Flow 20-29
•BOD5 85-110
SS 20-90
mgd
mg/1 BOD5 6-8 mg/1
mg/1 SS 8-15 mg/1

fj.ant
Plant Influent _ Primary _ Aeration ^ Final Effluent _
)
Figure 1
Rockaway Wast
Before Thermo
1 Sedimentation 1 Tank Clarification *~~
T i
1 w
1 	 , Return Sludge ^ f

^"'Waste
^^Vated Dilution Water
/ Mixed \ /MesophilicV /Thickenlnk
VThickening/ V 950 F / telutriation/ To Final
\^ y \^ / \ / Disposal

ewater Treatment Plant
philic Digestion Addition

-------
          Table  V

          Rockaway WTP Daily Gas Production
oo
vo
Month
*
September 197?
October
November
December
Average No
Recirculation
January 1980
February
March
April
May
Average With
Recirculation
Feb. to May 1980
Mesophilic
Digester
cu. ft. /day
79200
93800
90300
77200
87600
79200
88000
86800
76400
84300
83900
Thermophilic
Digester
cu. ft. /day
5300
8200
6900
7500
7000
8500
12700
13600
11900
17700
14000

-------
during recirculation.  The gas mixers in both digesters were found to be
causing the formation of large solids masses in the digesters with conse-
quent clogging of the overflow; it was found necessary to operate the
mixers only a few minutes per day to alleviate the condition.

     Garber (6) in Los Angeles had determined that the thermo-digested
sludge required half the dose of iron coagulant and produced almost four
times the yield on a vacuum filter as meso-digested sludge.  Accordingly,
to obtain some estimate of the improvement on coagulability achieved by the
use of the thermo-digestion in this instance, the meso- and thermo-digested
sludges were subjected to polymer treatment.  It was found, on a laboratory
scale, that using a high-molecular-weight, low-charge polymer //2535CH (as
manufactured by American Cynamid), the coagulability improved radically.
Specifically, dosages of up to A,000 ppm on meso-digested sludge did not
produce an end point, although some flocculation was observed.  In contrast,
the thermo-digested sludge released 73% of the water in 30 minutes in gravity
settling at a dose of 2,500 ppm.  Thenao-digested sludge, after a 3:1 elutri-
ation, required a lesser comparative dose of 1,650 ppm of the same polymer
to release 64% of the water within 30 minutes in gravity settling.

Destruction of Pathogens

     An effective way for the destruction of pathogenic organisms in sludge
is exposure to high temperature for an adequate period of time.  Many
researchers have shown that the effectiveness of disinfection increases
with temperature or time.  For example, Rudolfs et al. (1951)(7), using
Ascaris suum, found that:

     at 45° C, 2 hours:     had no effect
     at 50° C, 30 minutes:  retarded development
     at 50° C, 2 hours:     killed all ova
     at 55° C, 10 minutes:  killed all ova

Work by many others show similar findings with heat death of  ascaris
eggs (8).  Table VI also shows the effect of temperature and  time on
other pathogenic organisms (11).

     For the past several years, Garber and co-workers at the Hyperion
Treatment Plant in the City of Los Angeles have been operating a full-size
digester in the thermophilic temperature range of about 49 ° C, in parallel
with other digesters operating in the mesophilic temperature  range of about
35° C (9).  For approximately two years, in a cooperative program between
the Hyperion plant staff and the Municipal Environmental Research Labora-
tory  (MERL), grab samples of raw, mesophilic and thermophilic sludges were
forwarded to MERL for pathogenic organisms analyses.  A summary of the
analyses of bacteria is shown in Table VII  (10). Thermophilic digester
treatment consistently reduced the Salmonella densities to below the
detectable limits of the analytical procedure, whereas Salmonella were
consistently detected after mesophilic digestion.  The density of the
indicator organisms was reduced 2 to 3 logs more than was the case for
                                     898

-------
00
VO
IO
         Table VI

         Temperature and Time for Pathogen Destruction in Sludges
                                                                    Exposure Time  (Minutes)  for Destruction
                                                                        at Various Temperatures (  C)
Microorganisms
Cysts of Entamoeba histolytica
Eggs of Ascaris lumbricoides
Brucella abortus
Corynebacterium diphtheriae
Salmonella typhi
Escherichia coli
Micrococcus pyogenes var. aureus
Mycobacterium tuberculosis var.
Viruses
50°'C 55° C 60° C 65° C 70° C
, 5
60 7
60 3
45 4
30 4
60 5
20
20
25

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         Table VII

         Reduction  in  Bacterial  Densities  in Mesophilic  and  Thermophilic  Anaerobic

         Digestion  (20-day  detention)
                                                             Bacterial  Densities  (number/100 ml)*
o
o
Fecal Streptococcus
Fecal Coliform
Total Coliform
Salmonella
Raw Sludge Mesophilic
Feed Digestion
(36° C)
2.7 x 107 2.0 x 106
3.6 x 108 5.5 x 106
5.2 x 109 7.0 x 107
7530 62
Thermophilic
Digestion
(50° C)
3.7 x 104
2.9 x 104
6.4 x 104
BDL
         NOTE:  BDL - Below detection limits  (< 3/100 ml)
         *Average of measurements taken over 2-year period

-------
mesophilic digestion by thermophilic digestion.  Mesophilic digestion
reduced the density of Salmonella by 2 logs and indicator organisms
1 to 2 logs, as compared to raw sludge.

      Twelve sets of animal enteric virus analyses were conducted over the
2-year period (10).  Test results are as follows:


                                         PFU/GRAM OF LIQUID SLUDGE
          TYPE OF SLUDGE                     (2 to 5% SOLIDS)
          Raw                                     25.40
          Mesophilic Digested                      2.10
          Thermophilic Digested                    0.03
Thermophilic digestion produced a 2-log improvement over mesophilic
digestion.  In fact, viruses were not detected in 6 out of the 12
samples analyzed.  Based on the limited data, there was essentially
no effect on Ascaris lumbricoides concentrations in either type of
digester treatment.  The findings are in conflict with the reported
reasons for using the thermophilic process in the U.S.S.R.  Popova and
Bolotina (5), in their report on the practice of thermo-digestion in
Moscow, state "The most essential advantge of this process is the sanitary
quality of the thermophilic sludge.  According to the sanitary officials
of the health department, Viable eggs of helminths are absesnt from such
sludge."

      The Moscow and Los Angeles data agree on the degree of viral and
bacterial destruction but differ in the effect on helminths.  Note, how-
ever, that the Los Angeles digester was operated at 49°C  and Rudolph's
results indicate that temperature is very important in hulminth destruction.
It appears then that operation of the thermophilic stage slightly in excess
of 50°C would produce a sludge that is hygienically safe for disposal.

Potential Process Applications

      Since the 1980 EPA Municipal Wastewatear Facilities Construction
Need Survey showed that there will be over 4,200 municipal treatment plants
utilizing anaerobic sludge digestion by 1986, the EPA Office of Research
and Development initiated a separate study (12) that investigated the
feasibility of applying meso-thermophilic digestion to a major treatment
facility.  The District of Columbia Blue Plains treatment plant was selected
because it had anaerobic digesters in operation and the sludge management
methodology needed upgrading for operating and economic reasons.

      Based on review of the anaerobic sludge digestion options and how
they could be adapted to the existing facilities, the study recommends that
the thermophilic anaerobic digestion process be implemented on a full-scale
basis.  This recommendation is based on a thorough review of the present
state of practice in the United States and other countries.
                                    901

-------
      Although the meso-thermophillc digestion process could be the optimum
solution for other plants, the thermophilic process is recommended for Blue
Plains because it could be implemented with a miniunum of time and money.
Other significant advantages are: (1) increased sludge processing capa-
bility; (2) improved sludge dewatering as to coagulant demand and yield;
and (3) increased destruction of pathogens, all of which are pertinent to
the needs of the Blue Plains plant.

      It is especially important to check the structural competency of the
existing digesters and piping at the thermophilic temperatures, as well as
the temperature control system prior to start-up.

      A carefully formulated transition plan should be prepared so that
the transition can be carried out effectively and with minimum interference
with plant operations.
DISCUSSION

      It has been noted in the literature that the thermophilic digestion
process, by itself, presents a problem in that an excessively long period
of 6 to 12 months may be required to achieve a satisfactory operating per-
formance.  This required long period of adaptation of the biological species
to the hostile high temperature environment interferes with plant operation
and is costly in economic terms.  Therefore, to reduce substantially this
time period, it becomes mandatory to effectively seed thermophilic digesters.
In the case of meso followed by thermo, it is less critical that the thermo-
philic digester promptly achieve satisfactory performance.  Consequently, it
is elective to seed the thermo digester to expedite the operating performance
at a satisfactory level.

      The reader is cautioned that each plant will have a maximum upper
limit of the amount of digested sludge that can be recirculated.  It
should be pointed out that the proportion of digested sludge recirculated
continuously through the secondary treatment system should lie in the range
of 30% - 60%.  Moreover, operation should generally be conducted in the
lower part of this range at wastewater temperatures near 75° F, and in
the higher part of this range at temperatures near 55° F.


SUMMARY

      A full plant-scale test was conducted at the Rockaway Plant in
New York City with a connected population of 100,000 for a period of
5 months to evaluate a new method of reducing the amount and volume of
sludge produced from the activated sludge process.  This method involved
the novel use of: (1) high stability thermophilic digestion following
mesophilic digestion and (2) the recirculation of a portion of such
thermo-digested sludge directly to and through the secondary system
                                      902

-------
of the activated sludge process while the remainder was conducted to
a rethickening and elutriation step.  Operating results have demon-
strated that the volatile matter normally transported to sea after
meso-digestion was reduced by 2/3.  Moreover, the volume of sludge
produced was lowered by 2/3 without chemical or mechanical aids.
It was determined on a laboratory scale that the residual solids
exhibited improved coagulability having undergone thermo-digestion,
which change would improve the economics of all subsequent dewater-
ing processes.  The treatment process performed without significant
adverse effect on any accepted parameter due to the continuing re-
circulation of digested sludge through the activated sludge process.
                                 903

-------
REFERENCES
1.  Kraus, L.S.,  "Digested  Sludge  - An Aid  to  the Activated  Sludge
    Process," ibid., Vol. 18,  No.  6,  p.  1099 (Nov.  1946).

2.  Buhr, H.O. and J.F. Andrews, "Review Paper:   The Thermophilic
    Anaerobic Digestion Process,"  Water  Research,  11, 129-143 (1977).

3.  Rimkus, R.R., J.M. Ryan, and E.J. Cook, "Full  Scale Thermophilic
    Digestion at the West-Southwest  Sewage Treatment Works," Paper pre-
    sented at the Annual Water Pollution Control Federation Conference,
    Las Vegas (October 1980).

4.  Smart, J. and B.I. Boyko,  Full Scale Studies on the Thermophilic
    Anaerobic Digestion Process, Report  No. 59,  Ontario Ministry of the
    Environment, Toronto (1977).

5.  Popova, N.M. and O.T. Bolotina,  "The Present State of  Purification of
    Town Sewage and the Trend in Research Work in the City of Moscow,"
    Advances in Water Pollution Research, Vol. 2 (W.W. Eckenfelder, ed.).,
    MacMillan Co., New York (1964).

6.  Garber, W.F., G.T. Ohara,  S.K. Raksit,  and D.R. Olson, "Studies of
    Dewatering Anaerobically Digested Wastewater Solids at the Hyperion
    Treatment Plant," Progress in Water  Technology, 8_, No. 6, 371-378
    (1977).

7.  Rudolfs, W., L.L. Falk, and R.A.  Rogotzkie,  "Contamination of
    vegetables grown in polluted soil:   V helminthic decontamination,"
    Sewage Ind. Waste, 23:853-860  (1951).

8.  Graham, H.J., "Parasites and the  Land Application of Sewage Sludge,"
    Research Report No. 110, p. 10-11, Ontario Ministry of the Environ-
    ment, Toronto (1981).

9.  Ohara, G.T. and J.E. Colbaugh, "A Summary of Observations in Ther-
    mophilic Digester Operations," Proc. of the 1975 National Conference
    on Municipal Sludge Management and Disposal, Anaheim,  California,
    August 18-20, 1975, pp. 218-222.   Available from Information Transfer,
    Inc., 1160 Rockville Pike, Rockville, Maryland  20852.

10. Farrell, J.B. and G. Stern, "Sludge  Disinfection Techniques," Proc. of
    the National Conference on Composting of Municipal Residues and
    Sludges, (1977), pp. 142-153.   Available from Information Transfer,
    Inc., 1160 Rockville Pike, Rockville, Maryland  20852.  Library of
    Congress Catalog No. 77-94492.
                                     904

-------
11. Roediger,  H.,  "The Technique  of Sewage-Sludge  Pasteurization:  Actual
    Results Obtained in Existing  Plant,"  International Research  Group  on
    Refuse Disposal (IRGRD),  Information  Bulletin  Nos. 21-31, August 1964
    - December 1967, pp. 330-340.

12. Torpey, W.N.,  J.L. Andrews, and N.A.  Mignone,  "Evaluation of the
    Full-Scale Application of Anaerobic Sludge Digestion  at  the  Blue
    Plains Wastewater Treatment Facility  - Washington, D.C.," EPA  Project
    Summary 600/52-81-105,  July 1981;  Complete Report Available  from
    National Technical Information  Service,  Springfield,  Virginia  22161
    (Order No. PB  81-219-123).
                                  905

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RESEARCH SUPPORTED BY THE NATIONAL SCIENCE FOUNDATION RELATING TO TREATMENT
            OF WASTEWATER AND MANAGEMENT OF RESIDUAL SLUDGES
                              Edward H.  Bryan
                        National Science Foundation
                            Washington,  D.  C.
            The work described in this paper was not funded by the
            U.S. Environmental Protection Agency.  The contents do
            not necessarily reflect the views of the Agency and no
            official endorsement should be inferred.
                       Prepared for Presentation at:
                    8th United States/Japan Conference
                                    on
                       Sewage Treatment Technology

                                October 1981
                             Washington, D.C.
                                   907

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RESEARCH SUPPORTED BY THE NATIONAL SCIENCE FOUNDATION RELATING TO TREATMENT
OF WASTEWATER AND MANAGEMENT OF RESIDUAL SLUDGES


Edward H. Bryan
National Science Foundation
Washington, D.C.
ABSTRACT

     Scientific research has played an important role in development of our
present understanding of all matters relating to management of water.  This
knowledge has been applied by engineers in solving problems of availability,
quality, treatment, and use of water and in treatment of wastewater for reuse
of discharge to minimize adverse environmental impacts.  The roles of science
and engineering as they relate to management of water are becoming progres-
sively more important as pressures mount for its more intensive use.

     Since its establishment in 1950 as an independent agency of the Executive
Branch of the Federal Government, the National Science Foundation (NSF) has
provided support for research to broaden the base of understanding on topics
directly and indirectly relating to management of wastewater.  Between 1973
and 1981, NSF supplied substantial support for research on innovations in
management of sludges and in using wetlands to provide a degree of treatment
equivalent to that obtained through capital and energy-intensive, physical,
and chemical advanced (tertiary) treatment processes.

     Wetlands have been shown to be potentially capable of absorbing the
nutrient load from conventional secondary treatment processes without adverse,
short-term effects.  Full-scale use of a wetland for placement of a secondary
effluent is currently in its fourth year of operation and evaluation at
Houghton Lake, Michigan.

     The combined capacity of two installations for disinfection of sludges
using energized electrons in the United States, will be 300,000 gallons per
day with scheduled completion of the unit at Miami, Florida, in 1981.  The
concept of combining disinfection of sludges by use of energized electrons,
pipeline transport, and direct injection into topsoil on land dedicated to
use for stabilization of sludges appears to be a promising new approach to
management of sludges.
     Dr. Edward H. Bryan is Program Director, Water Resources and Environ-
mental Engineering in the Engineering Directorate's Division of Civil and
Environmental Engineering.  His prior program management responsibilities
since joining the National Science Foundation in 1972 have included Regional
Environmental Systems, Systems Integration and Analysis, Regional Environ-
mental Management, Community Water Management and Appropriate Technology.


                                      908

-------
INTRODUCTION

     In 1973, the National Science Foundation (NSF) began supporting research
on problems that had regional significance with regard to their potential
adverse environmental impact.  One concerned the pollutional impact of
effluents from secondary wastewater treatment plants on receiving waters from
nutrients remaining in the effluent.  Another concerned the currently large
and rapidly growing problem of managing sludges produced during treatment of
wastewater.  A common factor linking these two interrelated problems was a
desire to find solutions that were less capital and energy intensive than
conventional physical, chemical, and biological methods.

INNOVATION IN SLUDGE MANAGEMENT

     The context within which NSF's support of research on sludge management
started in 1974 was the projected increase in the amounts of sludge resulting
from implementation of new water pollution control legislation and imminent
foreclosure of ocean placement and incineration as options for dealing with
sludges.   NSF's program sought a better understanding of the basic elements
that comprise all systems for processing sludges as a step toward a new
concept that would be more efficient and acceptable than simple refinement
of current practices (1).

     The approach that NSF's program took was strongly influenced by results
from the initial project (2).  Investigators at the University of Texas found
that during conventional treatment of wastewater, most of the viruses were
concentrated in sludges where they remained viable during subsequent process-
ing.  When these sludges were incorporated into soil, viruses were adsorbed
on soil particles, remained viable for long periods of time* and were capable
of being released under conditions simulating rainfall.  These findings
suggested that disinfection of sludges might become an essential pretreatment
step for infected sludges that would be managed by placement on land, and the
need for a transport and placement method that would minimize the risk and
nuisance associated with processing, transporting, and application of sludge
to land.

     Since 1974, NSF's allocation in support of research directly relating
to sludge management totalled about $4 million.   The interdisciplinary
nature of this problem and the diversity of issues that were addressed is
evident from the summaries in Tables 1 and 2.  Research personnel from
more than 20 public and private institutions and organizations participated
in this effort and over 150 reviewers were consulted in evaluating the
unsolicited proposals that led to actions necessary to sustain this effort.

     The cost of sludge management is directly proportional to the amount
produced.  An initial logical step to minimize cost of sludge management would
be to select treatment processes for wastewater that minimize production of
sludges,  consistent with other treatment objectives.  The quality of sludges
also affects the cost of additional processing and management.  Regulation of
industrial discharges into the collection system to limit or prohibit entry
of heavy metals and toxic organic compounds is likely to be more


                                       909

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    TABLE  1-  RESEARCH SUPPORTED st THE NATIONAL SCIENCE FOUNDATION APPLIED TO MANAGEMENT of SLUDGES DERIVED FROM TREATMENT OF MUNICIPAL WASTEWATER
Ha-
1.
2-
j.
1.
5.
b-
7.
8.
9.
10.
11.
12.
13-
11.
15.
16.
17.
18.
19.
20.
21-
22.
23.
21.
INVESTIGATOR
BERNARD P. SAG IK
JAMES L- SMITH
JOHN G. TRUMP
EDWARD G- MERRILL
ANTHONY SINSKEV
THEODORE G. METCALF
RICHARD I. DICK
KOY HARTENSTEIN
MARY BETH KIRKHAM
WILLIAM J. MANNING
P.C- CHEO
C- FRED GURNHAM
JACK E- COLLIER
STEPHEN C. HAVLICEK
ROBERT S- INGOLS
GEORGE D- WARD
CHARLES FINANCE
ROGER BLOBAUM
STEPHEN J- MARCUS
LEON W. WEINBERGER
ROBERT W. KAUFMAN
CLARENCE GOLUEKE
ROGER HAAG
GEORGE 0- HARD
GEORGE D- WARD
ROY HARTENSTEIN
JAMES E. ALLEMAN
MARY BETH KIRKHAM
l2fJ£S_, .
DISCIPLINE
MICROBIOLOGY
AGRICULTURAL ENGINEERING
ELECTRICAL ENGINEERING
CHEMICAL ENGINEERING
NUTRITION/FOOD SCIENCE
MICROBIOLOGY
CIVIL ENGINEERING
INVERTEBRATE ZOOLOGY
AGRONOMY
PLANT PATHOLOGY
PLANT PATHOLOGY
CHEMICAL ENGINEERING
INDUSTRIAL ENGINEERING
ORGANIC CHEMISTRY
BIOLOGY
CIVIL ENGINEERING
FILM PRODUCTION
COMMUNICATIONS
ENGINEERING
SANITARY ENGINEERING
POLITICAL SCIENCE
ENVIRONMENTAL ENGINEERING
CIVIL ENGINEERING
CIVIL ENGINEERING
CIVIL ENGINEERING
INVERTEBRATE ZOOLOGY
CIVIL ENGINEERING
AGRONOMY
INSTITUTIONS. INVESTIGATORS AND THEIR DISCIPLINES
INSTITUTION
UNIVERSITY OF TEXAS
SAN ANTONIO, TEXAS
COLORADO STATE UNIVERSITY
FORT COLLINS, COLORADO
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
CAMBRIDGE, MASSACHUSETTS
UNIVERSITY OF NEW HAMPSHIRE
DURHAM, NEW HAMPSHIRE
UNIVERSITY OF DELAWARE INITIALLY, THEN
CORNELL UNIVERSITY, ITHACA, NEW YORK
STATE UNIVERSITY OF NEW YORK
SYRACUSE, NEW YORK
OKLAHOMA STATE UNIVERSITY, STILLWATER
UNIVERSITY OF MASSACHUSETTS, AMHERST
(WALTHAM FIELD STATION)
CALIFORNIA ARBORETUM FOUNDATION, Los
ANGELES ARBORETUM, ARCADIA, CALIFORNIA
GURNHAM AND ASSOCIATES, INC.
CHICAGO, ILLINOIS
COLLIER EARTHWORM COMPOSTING SYSTEMS,
INC., SANTA CLARA, CALIFORNIA
GEORGIA INSTITUTE OF TECHNOLOGY
ATLANTA, GEORGIA
GEORGE D- WARD AND ASSOCIATES
PORTLAND, OREGON
MEDIA FOUR PRODUCTIONS, INC.
HOLLYWOOD, CALIFORNIA
KOGER BLOBAUM AND ASSOCIATES
DES MOINES, IOWA
ENERGY RESOURCES COMPANY, INC.
CAMBRIDGE, MASSACHUSETTS
ENVIRONMENTAL QUALITY SYSTEMS, INC.
KOCKVILLE, MARYLAND
WESTERN MICHIGAN UNIVERSITY
KALAMAZOO, MICHIGAN
CAL RECOVERY SYSTEMS, INC.
RICHMOND, CALIFORNIA
KICKEL MANUFACTURING CORPORATION
SALINA, KANSAS
GEORGE D- WARD AND ASSOCIATES
PORTLAND, OREGON
GEORGE D. WARD AND ASSOCIATES
PORTLAND, OREGON
STATE UNIVERSITY OF NEW YORK
SYRACUSE, NEW YORK
UNIVERSITY OF MARYLAND
COLLEGE PARK, MARYLAND
KANSAS STATE UNIVERSITY
SUBJECT OF RESEARCH - TITLE OF PROJECT
POTENTIAL HEALTH RISKS ASSOCIATED WITH INJECTION OF
DOMESTIC WASTEWATER TREATMENT PLANT SLUDGES INTO
SOIL
MANAGEMENT OF SUBSURFACE INJECTION OF WASTEWATER
TREATMENT PLANT SLUDGES INTO TOPSOIL
DISINFECTION OF MUNICIPAL WASTEWATER TREATMENT
PLANT SLUDGES BY USE OF HIGH ENERGY ELECTRONS
INACTIVATION OF ENTERIC VIRUSES IN MUNICIPAL
WASTEWATER SLUDGES BY USE OF ENERGIZED ELECTRONS
PROCESS INTEGRATION FOR OPTIMAL MANAGEMENT OF
SLUDGES DERIVED FROM TREATMENT OF MUNICIPAL
WASTEWATER
STABILIZATION OF DOMESTIC WASTEWATER TREATMENT
PLANT SLUDGES BY SOIL INVERTEBRATES
AGRICULTURAL VALUE OF MUNICIPAL WASTEWATER
TREATMENT PLANT SLUDGES IRRADIATED WITH
ENERGIZED ELECTRONS
MECHANISMS OF PLANT VIRUS INACTIVATION IN SOILS
INJECTED WITH MUNICIPAL WASTEWATER AND SLUDGES
SOURCES AND CONTROL OF HEAVY METALS IN MUNICIPAL
WASTEWATER TREATMENT PLANT SLUDGES
CONVERSION OF MUNICIPAL WASTEWATER TREATMENT PLANT
SLUDGES INTO EARTHWORM CASTINGS FOR AMENDMENT OF
SOIL
EFFECT OF INFRARED RADIATION ON COMPACTION OF
MUNICIPAL WASTEWATER SLUDGES
CONTROLLED SOIL MICROBIAL DETOXIFICATION OF PHENOXY
HERBICIDE RESIDUES
SYNTHESIS OF A SYSTEM FOR MANAGEMENT OF MUNICIPAL
WASTEWATER TREATMENT PLANT SLUDGES, A 16 MM FILM
BASED ON RESEARCH IN ABOVE-LISTED PROJECTS (1) -
(6), INCLUSIVE
AN ASSESSMENT OF THE POTENTIAL FOR APPLYING URBAN
WASTES TO AGRICULTURAL LAND
PUBLIC HEALTH AND NUISANCE ASPECTS OF COMMUNITY
WASTEWATER SLUDGE MANAGEMENT
PREDICTION AND CONTROL OF HEAW METALS AND Toxic
ORGANIC SUBSTANCES IN MUNICIPAL SLUDGES
WORKSHOP ON THE ROLE OF EARTHWORMS IN STABILIZATION
OF ORGANIC RESIDUALS FROM DOMESTIC AND INDUSTRIAL
SOURCES
BENEFITS AND PROBLEMS OF COMPOSTING MIXTURES OF
MUNICIPAL SLUDGES AND SOLID HASTES
AGRICULTURAL UTILIZATION OF SLUDGES Dt <;VED FROM
TREATMENT OF COMMUNITY WASTEWATER
SUSCEPTIBILITY OF Mr. ST. HELEN'S VOLCANIC ASH TO
STABILIZATION BY USE OF ORGANIC SLUDGES
ELIMINATION OF SEPTIC TANK SLUDGE TRANSPORT BY
MANAGEMENT ON SITE OF ITS PRODUCTION
EARTHWORM-MICROBIAL INTERACTIONS DURING
STABILIZATION OF ORGANIC WASTES FOR RECOVERY OF
THEIR RESOURCE VALUES
BENEFICAL USE OF SLUDGES IN PRODUCTION OF BUILDING
COMPONENTS
PRODUCTIVITY OF LAND AND QUALITY OF WHEAT GROWN
25.  RAYMOND C.  LOEHR
       EDWARD F.  NEUHAUSER
                           MANHATTAN,  KANSAS

CIVIL/SANITARY ENGINEERING CORNELL  UNIVERSITY
SOIL BIOLOGY               ITHACA,  NEW YORK
USING SLUDGES AS ORGANIC SOURCES OF PLANT NUTRIENTS

STABILIZATION OF ORGANIC RESIDUES DERIVED FROM
TREATMENT OF SELECTED INDUSTRIAL AND MUNICIPAL
WASTES
                                                                      910

-------
TABLE I-   SUMMARY  2£ AWARDS  £X 1UI NATIONAL  SCIENCE  FOUNDATION in SUPPORT JJE RESEARCH m SjjjpjiE. MANAGEMENT.  FISCAL  YEARS  12Z2 -  128J.1
                                                              FISCAL  YEAR  OF  AWARDS  -  AMOUNTS  ARE  IN  THOUSANDS  OF  DOLI
No-     INSTITUTION (PRINCIPAL INVESTIGATOR)
 !•  UNIVERSITY OF TEXAS (BERNARD P. SAGIK)
 2-  COLORADO STATE UNIVERSITY (JAMES L- SMITH)
 3.  MASSACHUSETTS INSTITUTE OF TECHNOLOGY
       (JOHN G- TRUMP)
 4.  UNIVERSITY OF NEW HAMPSHIRE
       (THEODORE G- METCALF)
 5.  UNIVERSITY OF DELAWARE AND CORNELL UNIVERSITY
       (RICHARD 1. DlCK)
 b-  STATE UNIVERSITY OF NEW YORK - SYRACUSE
       (RoY HARTENSTEIN)
 7.  OKLAHOMA STATE UNIVERSITY (MARY BETH KIRKHAM)
     UNIVERSITY OF MASSACHUSETTS (WILLIAM J. MANNING)
 8-  Los ANGELES ARBORETUM FOUNDATION. (P-C. CHEO)
 9<  GURNHAM S ASSOCIATES, INC- (C- FRED GURNHAM)
10.  COLLIER EARTHWORM COMPOSTING SYSTEMS, INC.
       (JACK E. COLLIER)
11-  GEORGIA INSTITUTE OF TECHNOLOGY
       (STEPHEN C- HAVLICEK AND ROBERT S. INGOLS)
12.  GEORGE D. WARD & ASSOCIATES (GEORGE D- WARD)
13-  MEDIA FOUR PRODUCTIONS (CHARLES FINANCE)
14-  ROGER BLOBAUM 8 ASSOCIATES (ROGER BLOBAUM)
15.  ENERGY RESOURCES COMPANY, INC. (STEVEN MARCUS)
16.  ENVIRONMENTAL QUALITY SYSTEMS, INC-
       (LEON W. WEINBERGER)
17.  WESTERN MICHIGAN UNIVERSITY (ROBERT KAUFMAN)
18-  CAL RECOVERY SYSTEMS, INC- (CLARENCE GOLUEKE)
19.  RICKEL MANUFACTURING CORPORATION (ROGER HAAG)
20.  GEORGE D. WARD & ASSOCIATES (GEORGE D. WARD)
21.  GEORGE D- WARD & ASSOCIATES (GEORGE D. WARD)
22-  STATE UNIVERSITY OF NEW YORK - SYRACUSE
       (ROY HARTENSTEIN)
23.  UNIVERSITY OF MARYLAND (JAMES E- ALLEMAN)
24.  KANSAS STATE UNIVERSITY (MARY BETH KIRKHAM)
25-  CORNELL UNIVERSITY
       (RAYMOND C. LOEHR AND EDWARD F.  NEUHAUSER)
                         TOTALS
                                                    1972/73   1971    1975    1978
                                                    263-0     -     58-9    72-4
                                                             51-0    68-9    86-1
                                                            113-7   198-0  200.0
                                                                                 70.
43-0
59.1
                                                                          40.7

                                                                          65-0

                                                                          88.5
                        19/7   1978   1979   198.1L _1J8J_ JJUAL.
                        89.2   87.5     -      -      -    571-0
                        15.4     -                         221.4
                       285-0   27.2   90-0     -      -    983.9
 35.0


111.7

 87.8
 39.0
110.9
  9-7
 21.9
 25.0
 49.6
 92.13
 17-0

 77-2   77.8
150-7   90-0


 37.8

 15.6
                                                                                                 183.4
                                                                                                   2-8

                                                                                                 126-4
                                                                                                 201-4  123-2
                                                                                                    -    43.9"
                                                                                                         19.6
                                                                                                         25-0
                                                                                                                11.75
                                                                                                                24./5
                                                                                                                73.85
                                                                                                                41.15
                                                                                                                63- 85
                                                                                                                       180.
135-/

279.1

440-9

 87-8

 76.8
110.9
 25.?

 21-9

208-4
 52-4
 92-1
126.4
324-6

 48-?
 19-6
 25-0
 11-7
 24.7
 7J.8

 .1.1
 63.8
180-0
                                                           16177
 ALL AWARDS LISTED WERE MADE FROM THE WASTE MANAGEMENT STRATEGIES AND RESIDUALS MANAGEMENT ELEMENTS OF PROGRAMS  IN REGIONAL
 ENVIRONMENTAL SYSTEMS/MANAGEMENT AND COMMUNITY WATER MANAGEMENT EXCEPT AS NOTED IN ITEMS 2, 3, 4 AND 5, BELOW-
2
MNTERAGENCY TRANSFER OF FUNDS FROM THE U-S- ENVIRONMENTAL PROTECTION AGENCY'S MUNICIPAL ENVIRONMENTAL RESEARCH  LABORATORY,
 CINCINNATI, OHIO-                                                                                       ,
 RESOURCE SYSTEMS PROGRAM, DIVISION OF. ADVANCED ENERGY AND RESOURCES RESEARCH AND TECHNOLOGY, NATIONAL SCIENCE FOUNDATION-
 OFFICE OF PROBLEM ANALYSIS, DIRECTORATE FOR ENGINEERING AND APPLIED SCIENCE IN SUPPORT OF PLANNING FOR A PROGRAM IN APPROPRIATE
 TECHNOLOGY-
 PROGRAM IN APPROPRIATE TECHNOLOGY, NATIONAL SCIENCE FOUNDATION.
                                                               911

-------
efficient in improving the quality of sludges in that respect than subsequent
detoxification.  However, the presence of unstabilized organic matter and
pathogenic bacteria, protozoa, viruses and intestinal parasites is an inherent
characteristic of all wastewaters derived from or associated with human con-
tacts.  All sludge processing and management systems address common issues of
disinfection, detoxification, stabilization, transport and final placement.
The most efficient total system is the one that minimizes costs of achieving
acceptable resolution of these issues, consistent with the effect on treat-
ment operations with which it must be integrated.

     The concept that emerged from the NSF program pointed toward disinfection
by use of energized electrons, pipeline-transport to a suitable land appli-
cation site where the sludge would be injected into topsoil for stabilization
under carefully controlled conditions as having the attribute of minimum •
total cost.  The advantages of this concept beyond those directly associated
with elimination of costly dewatering processes and other capital and energy-
intensive manipulations include:

     •  Retention of the nutrient values that are lost during processing
        by digestion, composting and other treatment procedures.

     •  Elimination of conditioning agents and their residuals as
        potential contaminants of the final product.

     •  Elimination of construction and operating costs associated with
        plant capacity no longer needed to accommodate strong and process-
        disruptive return-flows from thickeners, digesters, elutriation
        devices, ash pits, drying beds, centrifuges, vacuum filters and
        similar equipment.

The concept of coupling electron-beam disinfection with direct injection of
sludges into topsoil was portrayed in a brief 16mm film entitled:  "New
Concepts in Sludge Management" (3).  A more comprehensive film was also
produced for use in briefing potential participants in a planned large-scale
experiment to study those attributes of the integrated concept that were
necessary to understand sufficiently to permit their use in engineering desigi
of full-scale systems (4).  In addition, a preliminary step was taken to
design the experiment itself as a basis for estimating its potential cost  (5).

     Research to determine the role of soil invertebrates in stabilizing
sludge led to new insights into the nature of stability as the concept is
used to characterize sludges (6).  Studies initiated to provide background
for determining the effect of high-energy electrons on chlorinated hydro-
carbons in sludges led to the observation of the complete destruction of a
herbicide  (monuron) and two polychlorinated biphenyls (3,4,2'-trichlorobi-
phenyl and 4-chlorobiphenyl) in water solutions  (7).

     Two recent publications summarized progress toward implementation of
large-scale disinfection of sludges by use of energized electrons  (8) (9).
The 170,000 gallon per day unit currently under construction at the Miami-
Bade Water and Sewer Authority's Wastewater Treatment Plant on Virginia Key
in Florida is expected to be operational during 1981, providing disinfection

                                      912

-------
 capability  for one-fourth of  the plant's production of sludge.  The original
 unit  used for the NSF-supported research at the Metropolitan District
 Commission's Deer Island Wastewater Treatment Plant in Boston was recently
 modified by the High Voltage  Engineering Corporation, expanding its nominal
 capacity from the original 100,000 gallons per day to 170,000.  This unit is
 currently operational and was used to refine the engineering design for the
 Florida installation.

 WETLANDS FOR WASTEWATER MANAGEMENT

      Complementary to research on management of sludges from primary and
 secondary treatment processes for wastewater, the National Science Foundation
 has been supporting research  to better understand the potential role that
 wetlands can play in managing both the water and nutrients contained in
 effluents from conventional secondary treatment processes.  While placement
 of a wastewater that had been freed of its demand for oxygen but which was
 rich  in nutrients into a wetland appeared to have only desirable consequences
 of increasing the wetland1s productivity, questions remained as to potential
 negative effects of this practice on the wetland ecosystem (10).

     Ecosystem models constructed during the initial two years of a study in-
 volving potential application of a secondary effluent to a peat wetland near
 Houghton Lake, Michigan (11)  (12), led to a two-year pilot-scale evaluation of
 the concept (13).  Results of that study were sufficiently encouraging to in-
 itiate the  full-scale placement of effluents from the Houghton Lake commun-
 ity's secondary oxidation pond of the 2000-acre wetland.  The wetland is so
 large in comparison to the load imposed on it that nutrient-removal has been
 observed to be virtually complete within 100 meters from the line of entry.
 A 20-year monitoring program was established by the Houghton Lake community
 to determine any changes in the biota of the wetland attributable to its use
 for wastewater management.  Initial results (14 (15) (16) (17) have been
 utilized to guide formulation of engineering design criteria for further
 application of this concept (18).   A wetland that emerged upon failure of a
 land-application system to fully absorb wastewater placed on it has also been
 studied to provide guidance for potential use of the "wetland-concept" by
 communities lacking nearby natural wetlands (19).

     In Florida, extensive studies have been conducted on cypress dome wet-
 lands near  Gainesville (20) (21) (22) and on a cypress stand wetland ne,,.r
 Jasper (23) to characterize both seepage and flow-through type wetlands for
 their potential role in conserving nutrients and renovating wastewater.  Over
 a six-year period, a test dome received the effluent from a small, activated
 sludge treatment plant serving a trailer park.   Studies included effects on
 local groundwater quality, tree-growth rate, seedling germination, mosquito
population and the survival characteristics and mobility of viruses.   Hydro-
 logical characteristics,  concepts of site management and characterization of
 the wetland's metabolism were studied and related to potential general use of
 this concept in Florida.   Studies at the Jasper site,  which has received
wastewater varying in degrees of prior treatment over a period of 60 years,
 are expected to provide insights into long-range effects of using wetlands
 for treatment of wastewater.
                                     913

-------
    TABLE ?•  SUMMARY at AWARDS MADE 12 SUPPORT RESEARCH JH£ PROGRAM DESCRIBED m IHE FILM;  "WETLANDS, - OUR NATURAL PARTNERS in WASTEWATEB MANAGEMENT*


                                                                                      TITLE OF THE PROJECT                  NSF PROGRAM AND PROGRAM MANAGER
FISCAL
 YEAR
1971/72



 1973



 19/3



 1971



 1975




 19/5




 1976


 1976




 1976
 1976
  TO

 1976
  TQ
 1977


 1977


 1978



 1978


 1978


 1978


 1978



 1979


 1979


 1979


 1980


I960


1980
INSTITUTION  AND PRINCIPAL INVESTIGATOR     AMOUNT  OF  AWARD
            (GRANT NUMBER)                   AND DURATION
           UNIVERSITY OF MICHIGAN,  JOHN A.  KADLEC    $133,550 FOR
                       (61  34812)                         12 MONTHS
           UNIVERSITY  OF FLORIDA,  HOWARD T-  ODUM
                       (GI  37821)
                                          $321,700  FOR
                                               24 MONTHS
           UNIVERSITY  OF  MICHIGAN,  JOHN  A.  KADLEC     $128,700 FOR
             AND ROBERT H-  KADLEC  (GI  34812)               12  MONTHS
           UNIVERSITY  OF  MICHIGAN,  ROBERT  H.  KADLEC  $131,800 FOR
                       (61  34812)                          12  MONTHS
           UNIVERSITY  OF  FLORIDA,  HOWARD T. ODUM
                       (ENV 73-0/823)
                                          $223,000 FOR
                                              12 MONTHS
           UNIVERSITY OF MICHIGAN,  ROBERT H.  KADLEC   $110,000  FOR
                       (ENV  75-08855)                      12 MONTHS
          WILLIAMS 8 WORKS, JEFFREY C- SUTHERLAND
                       (ENV 76-20812)'
                                         $31,200 FOR
                                               7 MONTHS
          UNIVERSITY OF MICHIGAN,  ROBERT H. KADLEC   $129,900 FOR
                       (ENV 75-08855)                     16 MONTHS
            UNIVERSITY OF  FLORIDA,  HOWARD  T-  ODUM      $223,600 FOR
                        (ENV  73-07823)                      12  MONTHS
          BOYLE ENGINEERING Co-, WALTER R. FRITZ    $43,'700 FOR
                      (ENV 76-23276)                     12 MONTHS

          UNIVERSITY OF MICHIGAN, ROBERT H. KADLEC  $43,500 FOR
                      (ENV 75-08855)                      4 MONTHS
          UNIVERSITY OF FLORIDA, HOWARD T. ODUM     $91,500 FOR
                      (ENV 77-06013)                     21 MONTHS

          WILLIAMS 8 WORKS, JEFFREY C- SUTHERLAND   $6,100 FOR
                      (ENV 76-20812)                      1 MONTHS

          BOYLE ENGINEERING Co., WALTER R. FRITZ    $163,759 FOR
                      (PFR 78-19199)                     21 MONTHS
          UNIVERSITY OF MICHIGAN, ROBERT H. KADLEC  $111,711 FOR
                      (ENV 77-23868)                     12 MONTHS

          UNIVERSITY OF FLORIDA, HOWARD T. ODUM     $20,800 FOR
                      (PFR 77-06013)                      0 MONTHS

          WILLIAMS & WORKS, JEFFREY C. SUTHERLAND   $85,103 FOR
                      (PFR 77-20273)                     19 MONTHS

          FLORIDA, STATE DEPARTMENT OF HEALTH AND   $18,072 FOR
            REHABILITATION, FLORA MAE WELL INGS           12 MONTHS
                      (FfR 77-26819)

          UNIVERSITY OF MICHIGAN, ROBERT H. KADLEC  $152,275 FOR
                      (ENV 77-23868)                     12 MONTHS

          FORUM, LTD., RONALD 6- CAPALACES          $59,381 FOR
                      (PFR 79-19067)                      8 MONTHS

          IMAGE ASSOCIATES, CLAYTON EDWARDS         $3,OUO FOR
                      (PFR 79-19066)                     1 MONTH

          UNIVERSITY OF MICHIGAN, ROBERT H. KADLEC  $37,528 FOR
                      (ISP 80-11690)    '                12 MONTHS

          UNIVERSITY OF FLORIDA, HOWARD T- ODUM     $27,299 FOR
                      (ISP 80-14973)                     12 MONTHS

          FORUM, LT-,  RONALD G-  CAPALACES           $14,500 FOR
                      (PFR 79-19067)                      1 MONTH
                                                            "THE .EFFECTS  OF  SEWAGE EFFLUENT  ON  WETLAND
                                                              ECOSYSTEMS"
 "CYPRESS  WETLANDS FOR WATER  MANAGEMENT,
   RECYCLING AND CONSERVATION"
                                                            "THE EFFECTS OF  SEWAGE EFFLUENT ON WETLAND
                                                              ECOSYSTEMS"
 "THE  EFFECTS  OF  SEWAGE  EFFLUENT  ON  WETLAND
  ECOSYSTEMS


 "FEASIBILITY  OF  UTILIZING  CYPRESS WETLANDS
  FOR CONSERVATION  OF WATER  AND  NUTRIENTS  IN
  EFFLUENT  FROM  MUNICIPAL  WASTEWATER  TREATMENT
  PLANTS

 "FEASIBILITY  OF  UTILIZATION  OF WETLAND
  ECOSYSTEMS  FOR NUTRIENT  REMOVAL FROM
  SECONDARY MUNICIPAL WASTEWATER TREATMENT
  PLANT EFFLUENTS"

 "USE  OF WETLANDS FOR  MANAGEMENT  OF  POND-
  STABILIZED  DOMESTIC WASTEWATER"

 "FEASIBILITY  OF  UTILIZATION  OF WETLAND
  ECOSYSTEMS  FOR NUTRIENT  REMOVAL FROM
  SECONDARY MUNICIPAL WASTEWATER TREATMENT
  PLANT EFFLUENTS"

 "FEASIBILITY  OF  UTILIZING  CYPRESS WETLANDS
  FOR  CONSERVATION  OF WATER  AND  NUTRIENTS  IN
  EFFLUENT FROM  MUNICIPAL  WASTEWATER  TREATMENT
  PLANT EFFLUENTS"

 "TERTIARY TREATMENT OF MUNICIPAL WASTEWATER
  USING CYPRESS  WETLANDS"

 "FEASIBILITY  OF  UTILIZATION  OF WETLAND ECOSYSTEMS
  FOR  NUTRIENT REMOVAL FROM  SECONDARY MUNICIPAL
  WASTEWATER  TREATMENT PLANT EFFLUENTS"

 "UTILIZATION  OF  CYPRESS WETLANDS FOR  MANAGEMENT
  OF MUNICIPAL WASTEWATER  TREATMENT PLANT  EFFLUENTS"

 "USE OF WETLANDS  FOR  MANAGEMENT OF POND-
  STABILIZED  DOMESTIC WASTEWATER"

 "ADVANCED TREATMENT OF COMMUNITY WASTEWATER  BY
  FLOW-THROUGH CYPRESS STRAND WETLANDS"


"WETLAND UTILIZATION  FOR MANAGEMENT OF COMMUNITY
  WASTEWATER"

 "UTILIZATION OF CYPRESS WETLANDS FOR  MANAGEMENT
  OF MUNICIPAL WASTEWATER TREATMENT PLANT EFFLUENTS"

"UTILIZATION OF WETLANDS FOR MANAGEMENT OF POND-
  STABILIZED DOMESTIC WASTEWATER"

"MOBILITY AND SURVIVAL OF VIRUSES IN CYPRESS DOME
  WETLANDS"
REGIONAL ENVIRONMENTAL SYSTEMS
  WASTE MANAGEMENT STRATEGIES
    JEROME S- DAEN

REGIONAL ENVIRONMENTAL SYSTEMS
  WASTE MANAGEMENT STRATEGIES
    RICHARD C. KOLF

REGIONAL ENVIRONMENTAL SYSTEMS
  WASTE MANAGEMENT STRATEGIES
    EDWARD H. BRYAN

REGIONAL ENVIRONMENTAL SYSTEMS
  URBAN/ RURAL ENVIRONMENTS
    EDWARD H. BRYAN

REGIONAL ENVIRONMENTAL MANAGEMENT
  RESIDUALS MANAGEMENT
    EDWARD H. BRYAN
                                                                                                               REGIONAL ENVIRONMENTAL MANAGEMENT
                                                                                                                 COMMUNITY WATER MANAGEMENT
                                                                                                                   EDWARD H. BRYAN
                                                            "WETLAND UTILIZATION FOR MANAGEMENT OF COMMUNITY
                                                              WASTEWATER

                                                            "UTILIZATION OF WETLANDS FOR WASTEWATER
                                                              MANAGEMENT," TREATMENT AND PRODUCTION OF A FILM

                                                            "UTILIZATION OF WETLANDS FOR WASTEWATER
                                                              MANAGEMENT," TREATMENT CONCEPT ONLY
                                                   COMMUNITY WATER MANAGEMENT
                                                       EDWARD H- BRYAN

                                                   COMMUNITY WATER MANAGEMENT
                                                       EDWARD H. BRYAN

                                                   GOVERNMENT AND PUBLIC PROGRAMS
                                                       SUSAN BARTLETT
                                                            "SOLIDS MOVEMENT IN WETLANDS"
                                                            "APPROPRIATE ENVIRONMENTAL SYSTEMS FOR
                                                              WASTE  MANAGEMENT"

                                                            "UTILIZATION OF WETLANDS FOR WASTEWATER
                                                              MANAGEMENT" (SUPPLEMENTAL AWARD)
                                                                                                               APPROPRIATE TECHNOLOGY
                                                                                                                   EDWARD H- BRYAN
                                                                                                                           APPROPRIATE TECHNOLOGY
                                                                                                                               EDWARD H- BRYAN
                                                                           914

-------
The wetlands projects in Michigan and Florida are the subject of a documentary
film produced in 1980 to summarize progress and to assist in bringing the
availability of the results of this research to the attention of potential
users (23).  A summary of awards made to support this research program is
contained in Table 3.

SUMMARY AND CONCLUSIONS

     New concepts for management of sludges produced during treatment of
wastewater and to manage effluents from treatment processes for conservation
of their nutrient and water content are needed which meet acceptable standards
of public health and environmental quality and which also conserve capital,
material and energy resources.  Wetlands appear to provide that potential for
effluents that have received  primary  and secondary treatment by conventional
physical and biological processing.  This concept is especially compatible
with the first principle of good sludge management, the introduction of a
tertiary step that in contrast to other physical, chemical or biological
processes does not produce sludge.  Direct injection of sludges into topsoil
is already in actual use in many locations in the United States.  The
concept of applying sludge to land that is dedicated to "receiving sludge
in perpetuity" was recently described as underway at the Reno-Sparks Joint
Water Pollution Control Facility at Reno, Nevada (25).

     The combined capacity of the Miami-Dade Virginia Key facility and that
at the Deer Island plant in Boston will total in excess of 300,000 gallons
per day for electron-beam disinfection of sludges by the end of this year.
The concept of combining disinfection, pipe-line transport and direct
injection of sludges into topsoil on land dedicated to function as a stabil-
ization bed remains as a promising concept for assessment of its acceptability
with regard to risk, technical and economic feasibility, and environmental
compatibility.

REFERENCES

1.  Bryan, Edward H. "Future Technologies of Sludge Management" in Proc. of
    the 1980 Spring Seminar:  "Sludge Management in the Washington, D.C.
    Area," National Capital Section, American Society of Civil Engineers,
    pp.  52-62 (May 1980).

2.  Malina, Joseph F., Ranganathan, K. R., Moore, B.E.D. and Sagik, B. P.,
    "Poliovirus Inactivation by Activated Sludge," pp.  95-106 in Virus
    Survival in Water and Wastewater Systems, Water Resources Symposium
    No.  7, Center for Research in Water Resources, The University of Texas
    at Austin (1974).

3.  "New Concepts in Sludge Management," 16mm Film No.  A04088/CJ, National
    Audiovisual Center,  Washington, D.C.  20409 (National Science Foundation,
    5 minutes, Color 1978).
                                     915

-------
 4.  "Synthesis of a Municipal Wastewater Sludge Management System," Media
     Four Productions,  Hollywood,  California.   Contact Edward H.  Bryan,
     National Science Foundation for information regarding its availability.

 5.  Smith, James L., Lutkin,  Maurice H., Latham, James S. and de Haai,  Alan,
     "Land Management of Subsurface-Injected Wastewater Liquid Residuals,"
     Interim Report, NTIS Accession No.  PB 280162 (November 1977).

 6.  Hartenstein, Roy,  "Sludge Decomposition and Stabilization,"  Science,
     Vol. 212, pp. 743-749 (May 15, 1981).

 7.  Merrill, Edward W., Mabry, David R., Scholz, Robert B.,  Coleman, Walter D.
     Trump, John G.  and Wright, Kenneth  A. "Destruction of Trace  Toxic
     Compounds in Water and Sludge by Ionizing Radiation," Water  1977,
     AIChE Symposium Series No. 178, Vol. 74,  pp. 245-250 (1977).

 8.  Trump, John G.  "Energized Electrons Tackle Municipal Sludge," American
     Scientist, Vol. 69, No.  3, pp. 276-284 (May-June 1981).

 9.  Thorburn, Brewster A. "Sludge Management Using Electron Disinfection,"
     Proc. of the 1981 Conference on Environmental Engineering, American
     Society of Civil Engineers, pp. 540-547 (July 1981).

10.  Bryan, Edward H. "The Potential Role of Aquaculture in Management of
     Wastewater," in Individual Onsite Wastewater Systems, pp. 273-280,
     National Sanitation Foundation (1981).

11.  Dixon, Kenneth R.  and Kadlec, John  A. "A Model for Predicting the Effects
     of Sewage Effluent on Wetland Ecosystems," Interim Report, NTIS Accession
     No.  PB 273024 (1975).

12.  Parker, P. E.,  Gupta, P.  K.,  Dixon, K. R., Kadlec, R. H. and Hammer, D. E.
     "REBUS, A Computer Routine for Predictive Simulation of Wetland
     Ecosystems," Interim Report,  NTIS Accession No. PB 291587 (1978).

13.  Kadlec, Robert H., Tilton, Donald L., Schwegler, Benedict R., "Wetlands
     for Tertiary Treatment,  a Three-Year Summary of Pilot Scale  Operations
     at Houghton Lake," NTIS Accession No. PB 295965 (1979).

14.  Kadlec, Robert H., Hammer, David E. and Tilton, Donald L., "Wetland
     Utilization for Management of Community Wastewater," NTIS Accession
     No.  PB 80-108228 (1978).

15.  Kadlec, Robert H.  "Wetland Utilization for Management of Community
     Wastewater, Operation Summary, 1978, Houghton Lake Wetlands  Treatment
     Project," NTIS Accession No.  PB 298308 (1979).

16.  Kadlec, Robert H., and Hammer, David E. "Wetland Utilization for Manage-
     ment of Community Wastewater, 1979  Operations Summary, Houghton Lake,
     Michigan," NTIS Accession No. PB 80-170061  (February 1980).
                                      916

-------
 17.  Kadlec, Robert H. and Hammer, David E. "Wetlands Utilization for Manage-
     ment of a Community Wastewater, 1980 Operations Summary, Houghton Lake
     Wetlands Treatment Project," NTIS Accession No. PB 81-235954 (March
     1981).

 18.  "Aquaculture Systems for Wastewater Treatment:  An Engineering Assess-
     ment," U.S. Environmental Protection Agency 430/9-80-006 and 007, MCD
     67 and 68,  (June 1980).

 19.  Sutherland, Jeffrey C. "Investigation of the Feasibility of Tertiary
     Treatment of Municipal Wastewater Stabilization Pond Effluent Using
     River Wetlands in Michigan," Final Report, NTIS Accession No. PB 275283
     (1977).

 20.  Odum, Howard T. and Ewel; Katherine C.  "Cypress Wetlands for Water
     Management, Recycling and Conservation," Annual Report, NTIS Accession
     No. PB 80-104714 (1975).

 21.  Odum, Howard T. and Ewel, Katherine C. "Cypress Wetlands for Water
     Management, Recycling and Conservation," Annual Report, NTIS Accession
     No. PB 273097 (1976).

 22.  Odum, Howard T. and Ewel, Katherine C. "Cypress Wetlands for Water
     Management, Recycling and Conservation,',' Final Report, NTIS Accession
     No. PB 282159 (1978).

 23.  Fritz, Walter R. and Helle, Steven C.  "Cypress Wetlands as a Natural
     Tertiary Treatment Method for Secondary Effluents," Final Report,
     NTIS Accession No.  PB 294566 (1978).

 24.  "Wetlands - Our Natural Partners in Wastewater Management," 16mm Film
     No. A03093/CJ,  National Audiovisual Center, Washington, B.C.  20409
     (National Science Foundation, 39 minutes, Color, 1980).

 25.  Briscoe Maphis  Environmental Update, Volume 1, No. 6 (April 1980).

ADDITIONAL REFERENCES - REPORTS FROM PROJECTS LISTED IN TABLES BUT NOT CITED

 1.  Appelhof, Mary.   "Workshop on the Role of Earthworms in the  Stabilization
    of Organic Residues," Vol. I - Proceedings and Vol. II - Bibliography,
    Beech Leaf Press, Kalamazoo, Michigan (1981).

 2.  Blobaum, Roger.   "Assessment of the Potential for Applying Urban Wastes to
    Agricultural Lands," Final Report, NTIS Accession No. PB 296037 (May
    1979).

 3.  Connery, Jan.  "Proceedings of a Workshop on the Health and  Legal
    Implications of  Sewage Sludge Composting," Energy Resources  Company, Inc.
    NTIS Accession No.  PB 296566 (February 1979).
                                      917

-------
 4.   Dick,  Richard I.  "Process Integration for Optimum Management of Municipal
     Wastewater Treatment Sludges," NTIS Accession Nos.  PB 295950 and
     PB 296910.

 5.   Gurnham,  G.  Fred.   "Control of Heavy Metal Content of Municipal Wastewater
     Sludge,"  Final Report,  NTIS Accession No. PB 295917 (May 1979).

 6.   Hartenstein, Roy.   "Stabilization of Community Wastewater Sludges by Soil
     Invertebrates," Final Report,  NTIS Accession No.  PB 286018 (September
     1978).

 7.   Kirkham,  Mary Beth.   "Agriculture Value of Irradiated Municipal Wastewater
     Treatment Plant Sludges," Final Report, NTIS Accession No. PB 80-107865
     (November 1979).

 8.   Lutkin,  Maurice H.  and Smith,  James L. "On-Land Disposal of Municipal
     Sewage Sludge:  A Guide to Project Development,"  Interim Report, NTIS
     Accession No. PB 271144 (July 1977).

 9.   Metcalf,  Theodore G. "Control of Virus Pathogens in Municipal Wastewater
     and Residuals by Irradiation With High Energy Electrons," Final Report,
     NTIS Accession No.  PB 272347 (September 1977) and PG 80-104086
     (November 1979).

10.   Sagik,  Bernard P.  and Sorber,  Charles A. (Editors).  "Risk Assessment
     and Health Effects  of Land Application of Municipal Wastewater and
     Sludges," University of Texas at San Antonio, NTIS Accession No.
     PB 289675 (December 1977).

11.   Smith,  James L. and Bryan, Edward H. (Editors).  "Williamsburg Conference
     on Management of Wastewater Residuals," Publications No. 18599 (1976)
     and 20182, revised (1977), Colorado State University, 162 pp., NTIS
     Accession No. PB 262544.

12.   Trump,  John G. "High Energy Electron Radiation of Wastewater Liquid
     Residuals," NTIS Accession No. PB 279489 (December 1977).

13.   Trump, John G., Merrill, Edward H. and Sinskey, Anthony J. "High
     Energy Electron Radiation of Wastewater Liquid Residuals," NTIS
     Accession No. PB 297593  (February 1979).
                                       918

-------
   REMOTE  SENSING  OF  SEPTIC  SYSTEM  PERFORMANCE
     USING COLO,R  INFRARED  AERIAL  PHOTOGRAPHY
        David  W.  Hill  and  Rebecca  B.  Slack
         Surveillance  &  Analysis Division
                    Region IV
       U.S.  Environmental  Protection  Agency
                 Athens, Georgia
 Technical  information  developed  and  provided by:
              E.  Terrance  Slonecker
 Environmental  Photographic  Interpretation  Center
       U.S.  Environmental  Protection  Agency
               Warrenton,  Virginia
This paper has been reviewed in accordance with
the U.S. Environmental Protection Agency's peer
and administrative review policies and approved
for presentation and publication.
                  Presented at:
        8th  United States/Japan  Conference
                        on
          Sewage  Treatment Technology

                   October  1981
                Washington, D.C.
                      919

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REMOTE SENSING OF SEPTIC SYSTEM PERFORMANCE
USING COLOR INFRARED AERIAL PHOTOGRAPHY
David W. Hill and Rebecca B. Slack
Surveillance & Analysis Division
Region IV
U.S. Environmental  Protection Agency
Athens, Georgia

Technical information developed and provided by:
E. Terrance Slonecker
Environmental Photographic Interpretation Center
U.S. Environmental  Protection Agency
Warrenton, Virginia
ABSTRACT

       Failed septic leach fields resulting in surfacing of partially
treated wastewater to the ground surface can frequently be detected by
remote sensing. The surfacing nutrients may increase the growth of vege-
tation which shows as a brighter red on color infrared (CIR) aerial
photographs.  Effluent continually ponded on the surface will  eventually
kill the vegation by suffocating the roots.  Thus, depending upon the
severity of the failure, CIR photographs may reveal  red stripes that
delineate the tile field, bright red plumes in a downslope direction,
brown spots where vegetation has died, and dark blue spots denoting
standing surfaced effluent.
INTRODUCTION

       As a result of the Federal  Water Pollution Control  Act (P.L.
92-500) and the 1977 Clean Water Act (P.L. 95-217), the Environmental
Protection Agency (EPA) was given  the authority to grant funds for the
construction of sewage collection  systems.  Under the eligibility require-
ments for the construction grants  program, Federal rules and regulations
clearly state that the need for wastewater treatment facilities be proven
by documenting the number of septic field failures within the existing
target area, and assessing their effect upon water quality and public
health in general (1).

            "New collector sewers  should be funded only when the
       systems in use (e.g., septic tanks or raw discharges from
       homes) for the disposal  of  wastes from the existing population
       are creating a public health problem, contaminating groundwater,
       or violating the point source discharge requirements of the Act.
       Specific documentation of the nature and extent of health,
       groundwater and discharge problems must be provided in the
       facility plan.  Where site  characteristics are considered to
       restrict the use of on-site systems, such characteristics


                                  920

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       (e.g., groundwater levels, soil  permeability,  topography,
       geology, etc.) must be documented by soil  maps, histori-
       cal data, and other pertinent information.  The facility
       plan must also document the nature, number and location
       of existing disposal  systems (e.g., septic tanks) which
       are malfunctioning.  A community survey of individual
       disposal systems if recommended  for this purpose, and
       is grant eligible."

       Originally, the only way to satisfy this program requirement
was the door-to-door survey.  This, however, required large commit-
ments of personnel, time, money, and technical assistance.  Also, a
question of validity often arose because of local controversy some-
times surrounding sewer projects.  Clearly, an alternative survey
method was needed.

       Surface failure of septic leach  fields is usually caused by
one or more of the following:

        •   The soil is too compacted causing very slow perco-
            lation rates.

        •   There is a close, underlying, impervious layer
            below the drainage field.

        «   The water table is close to the surface during
            the wet season.

        •   Breakage or mechanical malfunctions exist.

        «   The septic tank itself is overdue for a cleaning.
            This allows the loss of normally removed materials
            to coat and seal the sides  and bottom of the perco-
            lation trenches.

       Only those malfunctions which are noticeable on the surface
can be detected on aerial imagery.  Failures related to sewage back-
ing up into the home, or too rapid transport through the soil into
the groundwater, cannot be detected via remote sensing.  In instances
where the latter is occurring, the groundwater monitoring studies may
be necessary to determine the existence of a problem.
HISTORY

       The first known documentation of septic field problems using
remote sensing was in Greensboro, North Carolina, in 1974.  Although
the results of this initial survey were not definitive, it did show
promise that a specialized technique for septic system analysis was
feasible (2).  By employing stereo pairs of "false-color" infrared
and conventional color photography, an analytical technique was
developed in 1977 at the EPA-Environmental Photographic Interpreta-
                                  921

-------
tation Center (EPIC) that has since been shown to be reason-
ably successful  depending upon the climatic and soil conditions
at the time of over flight.  EPIC produced several  photo interpre-
tation "keys" on septic field analysis and initially tested them
on seven communities in EPA, Region V.  This technique was touted
to have $36 million over conventional  techniques (3).  In early
1978, EPIC's technique was tested again in Hawkins, Greene and
Union Counties in Tennessee.  These communities were chosen
because of their geologic structure, soil  and topographic condi-
tions, and their pressing need for a disposal system.  The photo-
graphic interpretation was field checked,  and out of 55 suspected
failures, 52 were confirmed - an accuracy  of 94.5 percent.  This
aerial survey reinforced the suspicions of Tennessee public health
officials that current septic tank systems were not satisfactory
for disposal of wastes within the study area.

       The EPIC and other remote sensing techniques for septic
field analysis have been used often as a part of the 201 Construc-
tion Grants Process.  The primary document describing the photo-
interpretative keys is still being reviewed within EPA and will
be published by the Agency as a separate document.
METHODOLOGY

       The technique currently uses both color (Kodak Ektachrome
2448) and color infrared (Kodak Ektachrome 2443) photography.  Color
infrared is the primary tool; standard color photographs are also
used for orientation purposes and sometimes for verification.  A 60
percent end lap of each photograph is required for stereo viewing to
obtain topographic information.  The photo interpreter scrutinizes
the lot of each house for signatures of septic tank leachate such as
vegetative distress or enhanced growth, and excessive soil moisture.
A signature is an identifiable pattern characteristic of a certain
specific object or situation.  The signature key for septic tank
failure developed by EPIC is summarized as follows (2).
Surface Failure

       The obvious, blatant manifestations of septic system failure
on CIR photographs are characterized by a deep red color and one or
more dark gray or black spots where the actual septic effluent has
surfaced and killed the surrounding vegetation (see Figure 1).
Often, if the failure is severe, the effluent will break out into
the driveway or street and run into storm sewers or surface waters.
This type of failure may represent a health problem, especially if
the effluent is standing stationary or occurs many times in a given
area.
                                  922

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Figure 1.  Black and White Copy of a Color Infrared Photograph,
           Typical Signatures of Septic Field Failures Are:
           (A)  Overflow Into Street,
           (B)  Dead Grass,
           (C)  Lateral Lines Defined by Lush Grass.

                                923

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Seasonal  Failure

       This signature is less definitive than the surface failure
but nevertheless is readily identifiable with a high degree of
accuracy.  The seasonal  failure may not show surfacing effluent
when the photograph was  taken but there are signs that either all
or part of the system has failed in the past, or will  probably
fail in the future when  seasonal conditions, such as excessive
rain or a high water table, will strain the system.  This signa-
ture is characterized by unusually lush growth caused by excessive
surface moisture.  In many cases, all or part of the disposal system
will be well defined by  the lush growth directly above it.  Clear
delineation of the lateral lines is usually cause for subsequent
ground verification, even though such systems may not be failing.
Also, evidence of past failure on the surface, such as dead vege-
tation in the form of a  plume over all or part of the septic
leachate field, is similarily classified.

Seasonal  Stress

       This signature is the least definitive of all the septic
signatures but is still  very important from a planning viewpoint.
Seasonal  stress signatures depict excessive moisture at or near
the ground surface that  may be related to septic system problems.
Seasonal  stress signatures are characterized by faint or partial
definition of the lateral lines, excessive growth of vegetation
over the probable location of the leach field, or any general sign
that there is moisture near the surface.

       Failure signatures are not always obvious and training is
required to produce a proficient photo-interpreter.  Similar signa-
natures can be caused by common occurrences such as uneven spreading
of lawn fertilizer, manure piles, compost heaps and animal droppings.
For these reasons, field checking a perentage of the area is always
recommended.   In some cases, depending upon the soils of the partic-
ular area, the outline of the drainage line(s) of a properly function-
ing septic system can be distinguished on aerial photography.  This
peculiarity points up the need for tailoring  "photo interpretation
keys" to specific geographic areas (4).
EXAMPLES

       Using the above "signatures" as photo interpretation keys,
potential septic system failures have been identified in several
study ares.  The following examples are chosen from the Southeastern
United States  (5):

        «   Louisville (Jefferson County), KY
            (Flown in November 1979)
            Very extensive failure was noted.
            A  field check in January 1980 of 70 percent of the
                                  924

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     area showed 323 surface failures and 565 seasonal
     failures.  During rainy weather, drainage from these
     failed systems would wash into the combined sewers
     which serve as a direct conduit to the Ohio River.

 •   Maryville (Blount County),  TN

     (Flown in October 1980)
     This study showed the greatest number of failures
     or problems yet recorded in a single study:

       259 surface failures
     1,445 seasonal failures
     1,095 seasonal stress

     2,799 total  problems

 •   Orlando (Orange County), FL
     (Flown November and December 1980)
     This was a pilot study that determined the success of
     these techniques when applied to the unique climate and
     sandy soils of central Florida.  Results in the test
     area showed:

      47 surface failures
     232 seasonal failures
     167 seasonal stress

     446 total problems

 •   Apalachicola area (Gulf, Franklin, and Wakulla Counties),
     FL (Flown January and February 1981)
     These detection techniques  for this coastal area are
     currently being studied as  a research project.  Normally,
     remote sensing is not suitable for use along beaches or
     other areas of unconsolidated sand.  However, this area
     is part of the "Piney Woods Flatlands" which is underlain
     by an extensive hardpan.  The hardpan may make use of this
     technique possible.  This project was undertaken to determine
     possible sources of cholera organisms which are reaching
     production shellfish beds in Apalachicola Bay.

Nationwide, septic field failure surveys using this remote sensing
sensing technology have been conducted in the following locations
including those detailed above)  during the fiscal years shown:
1978                                              USER
     Lake Geneva, WI                      U.S. EPA Region V
     Crystal  Lake, MI                              "      V
     Silver Lake, WI                               "      V
     Otter Trail  Lake, MN                          "      V
                         925

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            Crooked & Pickerel  Lakes, MI                  "      V
            Nettle Lake, OH                               "      V
            Steuben Lakes, IN                             "      V
            Green Lake, MN                                "      V
            Spearfish, SD                                 "      VIII
            Smith Mountain Lake, VA                       "      III and
                            Virginia State Water Pollution Control  Board
            Hatboro/Horsham, PA                  U.S.  EPA Region III
            Upper Nazareth, Bushkill & Plainfield, PA       "      III
            Surgoinsville, Baileytown & Luttrell, TN       "      IV
            Stanley Co., NC                           Stanley Co.
                                                      Dept. of Health

       1979
            Topeka, KS                           U.S.  EPA Region VII
            Jefferson Co., KY                             "      IV
            Chalfont, New Britain & Doylestown, PA        "      III
       1980
            Lower Morel and, Abington & Bryn Athyn, PA     "      III
            Blount Co., TN                                "      IV
            Seattle, WA                                   "      X
       1981
            Delaware Co., OH                                     V
            Clermont Co., OH                              "      V
            Orlando, FL                                   "      IV
            Lewes/Rehoboth, DE                            "III
CONCLUSIONS

       Based upon the results obtained thus far, the manifestations
or photo signatures of failed septic leach fields are best distinguish-
ed on normal color or color infrared photographs at scales of 1:10,000
or larger depending upon the quality of the film and camera system.

       Some limitations on the use of remote sensing for septic tank
system failure analysis have been encountered.  Two of the most signi-
ficant limitations are related to soil/vegetation "homogeneity" and
tree cover.  Failing systems situated in soils which exhibit a wide
range of photo signatures, such as varying soil color/tone and "patchy"
vegetative cover (e.g., some sandy soils around lakes), are sometimes
difficult to distinguish from naturally occurring phenomena.  In areas
with a large percentage of tree cover, failing septic systems may be
obscured by foilage and/or shadows. These conditions can be minimized
by flying at specific times of the day or year.  This type of technique
optimization is continuing to further reduce the problem of "false nega-
tives," i.e., systems which are actually failing but are not identified

                                  926

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by the photographs.  This aspect of the technique is critical  to the
ultimate acceptance of procedure, since "false positives," i.e., the
apparent failure of well-operating on-site systems, merely cause an
increase in the ground verification effort, while a significant number
of false negatives can obviate the utility of the whole procedure.

       The big advantage of this technique is cost-savings.  The cost
may be as little as 10 percent of the cost of a door-to-door survey.
In fact, Region V estimated a savings of $51  million during 1980,
attributed, in significant part, to this technique.  For this a team
of seven empolyees was awarded the Excalibur  Award for Excellence
in Government Service.

       This technique is an excellent example of how color infrared
aerial photography can be put to practical use in saving millions of
taxpayer dollors.
REFERENCES

1.  Rhett, J. T., 1978.  Construction Grants Program Requirements
    Memorandum PRM 78-9, "Funding of Sewage Collection Systems
    Projects," U.S. Environmental Protection Agency, Washington, D.C.

2.  Slonecker, E. T., 1981.  Septic Systems Failure Analysis via
    Color/Color Infrared Aerial Photography, Virginia Polytechnic
    Institute, Blacksburg, Va.

3.  EPA Journal. May 1980.  Office of Public Awareness, Vol. 6,
    Number 5, p. 30.

4.  Crouch, L. W., 1979.  Remote Sensing as a Field Method for
    Assessment of Soil Moisture, University of Miami, Oxford, OH.

5.  Hill, D. W., Slack, R. B., and Slonecker, E. T., 1981.   "Remote
    Sensing of Failed Septic Leachate Fields,"  The Proceedings of
    the 1981 National Conference on Environmental Engineering, ASCE
    Environmental Engineering Division, Atlanta, GA.
                                   927

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  TWO-PHASE ANAEROBIC DIGESTION OF ORGANIC WASTES
           Sambhunath Ghosh, Ph.D.
       Manager, Bioengineering Research
          Institute of Gas Technology
              Chicago, Illinois
The work described in this paper was not funded by the
U.S. Environmental Protection Agency.  The contents do
not necessarily refelct the views of the Agency and no
official endorsement should be inferred.
         Prepared for Presentation at:
      8th United States/Japan Conference
                       on
         Sewage Treatment Technology

                 October 1981
               Washington, D.C.
                         929

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TWO-PHASE ANAEROBIC DIGESTION OF ORGANIC WASTES

Sambhunath Ghosh, Ph.D.
Manager, Bioengineering Research
Institute of Gas Technology
Chicago, Illinois

ABSTRACT

     Anaerobic digestion is a multi-step biochemical process mediated by
several microbial groups (phases) having significantly different physiology,
nutritional requirements, growth kinetic and metabolic characteristics,  en-
vironmental optima, and sensitivity to environmental stresses.   Conventional
engineering application of this process provides for concurrent enrichment
of the various microbial phases under an identical environment; this leads to
slow overall process kinetics, higher capital costs, low net energy production
efficiency, and other disadvantages.   A multi-stage advanced digestion process
in which the microbial phases are enriched in separate optimized environments,
and the substrate is stabilized by sequential acidogenic and methanogenic fer-
mentations is discussed.  The process, known as two-phase digestion, is  a
generic system, and could consist of two or more continuous stirred-tank,
plug-flow, packed-bed, or fluidized-bed fermentors.   The energetic,
kinetic, and economic advantages of the two-phase process are
discussed with reference to its application to several soluble and solid
organic wastes.  The status-of development of the two-phase process,
potential problems, and research needs are discussed.

INTRODUCTION

     Anaerobic digestion is a multi-step biochemical process which is mediated
by several symbiotic microbial groups or phases.  As indicated in Figure 1.
the overall digestion process consists of the following major coupled reaction
steps;

•    Enzymatic hydrolysis of particulate and high-molecular-weight substrates
     to simple monomers

•    Conversion of the monomers to higher fatty acids, carbon oxides  (mainly
     C02), hydrogen, and acetate

•    Degradation of the higher fatty acids to acetate and CO-

•    Cleavage of acetate and/or reduction of C0~ to form methane.

The first two steps outlined above are carried out by a group of acidogenic
bacteria,  It is believed that the third reaction step is conducted by the
so-called "acetogenic" organisms which derive energy by oxidizing the higher
fatty acids to acetate, hydrogen, and C02 (1).  Little information exists on
the physiology, kinetic properties, and nutritional and metabolic character-
istics of the acetogens.  Cleavage of acetic acid, which is believed  to be
the major substrate for methane formers in digestion of wastes, is the
                                     930

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 slowest and the least energy-yielding of the two methane-forming reactions (2).

     In view of the above, anaerobic digestion of organic wastes may be viewed
 as a two-phase process in which acid-forming organisms convert the process
 feed to acetic acid, which is next transformed to methane and CC^ by the
 methane-forming bacteria.  The acid-forming phase could be controlled by any
 one of the steps of hydrolysis, conversion of the hydrolytic products to
 acetate, or formation of acetate from higher fatty acids.

     There is ample information in the literature to indicate that the dominant
 digesting populations differ significantly from each other with respect to
 physiology, nutritional requirements, metabolic characteristics, growth kinetic
 capability, environmental optima, and sensitivity to environmental stresses (3,4),

     Two approaches could be employed in engineering application of the multi-
 phase digestion process to stabilization and gasification of organic wastes:

 •    Coculturing of the several microbial groups in a single fermentor
     (digester) under identical operating and environmental conditions

 •    Enrichment culturing of the microbial groups under optimized environments
     in separate digesters.

 ENGINEERING APPLICATION - CONVENTIONAL DIGESTION

     In traditional engineering application, anaerobic stabilization of
 concentrated organic feeds is provided by one of the following process
 configurations (3):

 •    Standard-rate digestion

 •    High-rate digestion

 •    Stage digestion

 •    Anaerobic contact process.

 These processes provide for the coculturing of the acid-forming and methane-
 forming populations in slurry-phase digesters under the same physical and
 chemical environments.  The design and operation of these processes are dic-
 tated by the sensitivity and kinetic limitations of the slow-growing methane
 formers.   Because the generation time of methane organisms has been estimated
 to be between 2 and 11 days for waste digestion conditions (4), a minimum
retention time between 3 and 16 days is required to prevent washout of the
rnethanogenic organisms.   In actual practice, a digester retention time of 10
 to 30 dayo is provided,  depending on waste properties, degree of mixing,  etc.,
 for reliable process performance (5),

     There are serious limitations as to the retention time as well as organic
 loading that can be applied on conventional mixed-phase digestion to obtain
stable process performance, and acceptable gasification and stabilization
                                     931

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efficiencies.  This point is illustrated in Figure 2, which depicts  the results
of mesophilic (35°C) conventional high-rate digestion of a high-chemical oxygen
demand (COD)(12,000-26,000 mg/&)  soft drink-bottling waste at various  loadings
and retention times (6).  The data show that as the loading was increased from
a low value of 0.04 Ib VS/ft3-day to a modest level of 0.125 Ib VS/ft3-day, the
feed, because of its high biodegradability, was rapidly metabolized by the acid
formers to volatile fatty acids which accumulated to high levels inhibitory to
methanogenic activity.  The underlying reason for the resulting digester upset
was the kinetic imbalance between the rates of production and utilization of
volatile acids,  which in this case ensued when a retention time of 10 days and
a feed volatile solids  (VS) concentration of only 20 g/£ were applied.  The
degree of this imbalance increased when attempts were made to operate the high-
rate digester at still shorter retention times and higher loading rates
(Figure 3).   Digester upsets like this which arise due to unbalanced activities
of acid and methane formers are difficult to prevent or correct because it is
not possible to control and manipulate the activity of either group of organisms
without affecting the activity of the other.  In view of the above,  the primary
disadvantages of conventional mixed-phase anaerobic digestion are:

•    Long retention times

•    Low loading rates

•    Occurrence of unbalanced digestion.

Long retention times and low loading rates in turn lead to the following
additional disadvantages:

•    Large digestion tanks and large land area requirement

•    High capital investment for the installation of the large digestion
     tanks and associated equipment

•    Difficulty of mixing in large tanks --- up to 60% of the volume of
     conventional digestion tanks is occupied by scum, sludge deposits,
     incrustations, or dead space

•    Low overall stabilization and gasification rate

•    Maintenance of the acid formers in the stationary growth phase, and
     consequent retardation of the hydrolysis and acidification reactions.

Also, as indicated above, the conventional digestion process is vulnerable to
varying -loading rates and retention times which could easily lead to unbalanced
digestion, process instability, and unreliable performance.

    Last,  but not least important is the fact that conventional anaerobic
digestion processes could easily have a negative energy balance: that is, the
total external energy input (excluding the energy content of the waste organics)
could exceed plant methane energy output, when dilute organic slurries are
digested at low loading rates.  This is illustrated in Figures 4 and 5 which
                                      932

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depict the net energy production ratio (NEPR) [defined as the ratio of the
energy value of the useable energy product (methane), Ep,  and the sum of  all
other energy inputs, E^,  excepting that of the  feed]  as  functions of feed
consistency and loading rate.   Net energy production  ratios are less than
one — this indicates that the process has a negative  energy balance and is  a
net energy consumer — when the feed slurries are so dilute that the sludge
heating requirement is excessive, or when the loading rate is so low that
unduly large digesters are required and excessive heat inputs are needed  to
compensate for heat losses from these digesters.

ADVANCED DIGESTION - - THE TWO-PHASE CONFIGURATION

      Advanced digestion utilizes process configurations that could over-
come the aforementioned limitations of conventional digestion, it also
permits process operation at much higher loading rates and shorter hydraulic
retention times (HRT's) than those of the conventional process.  As depicted
in Figures 2 and 3, digester operation at increased loadings and reduced
HRT's leads to the enrichment of an acid-forming culture precluding the
establishment of a stable methane-fermentation phase.  Since the natural
response of an anaerobic digester to high-loading short-HRT operation is
separation of the acid-forming phase, it appears reasonable to assist this
process and develop a staged system in which conversion of the feed to fatty
acids is optimized in the first stage.  Because conditions promoting optimum
substrate-to-acids conversion are not conducive to stable and efficient acid-
to-methane conversion, acidic effluents from the first-stage acid digester must
be methanated in a separate 'methane-phase digester operated in tandem with the
first-stage acid digester.  Thus, a multi-stage two-phase process, as first
suggested by Babbitt and Baumann (7) and later developed by Pohland and Ghosh
(3,8), Ghosh et^ al^. (9),  and others, evolves naturally when anaerobic digestion
is conducted at high loading rates and short retention times in the interest of
enhanced substrate conversion rate, reduced plant capital cost, and increased
net energy production efficiency.  Thus, two-phase digestion is an advanced
generic multi-stage process in which the acid-forming and the methane-forming
bacterial phases are optimized in separate reactors (stages) to substantially
enhance the overall process kinetics and NEPR,  and reduce plant capital cost.

Reactor Designs

     The simplest two-phase system consists of two separate digesters operated
in series.  If CSTR reactors are used, then the acid  digester is usually much
smaller than the methane-phase digester.  Anaerobic settlers can be used in
tandem with each digester to permit densification and recycling of settled
effluent solids to increase microbial and substrate solids retention times
(SRT's) (8, 10).  Depending on the feed properties and operating modes, other
reactor designs including plug~flow, packed-bed (anaerobic filter), or
fluidized-bed (also referred to as expanded bed and upflow sludge blanket)
could be used.  For low suspended-solids (SS) feed, an upflow anaerobic
filter appears more attractive for methane-phase fermentation, since it allows
process operation at a substantially lower HRT.  Finally, it should be noted
that a two-phase digestion process could conceivably  consist of more than two
digesters with more than one reactor design used to optimize each digestion
phase.
                                      933

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Culture Enrichment Techniques

     Several techniques have been proposed for selective enrichment and op-
timization of the acid-forming and methane-r-f orming phases.   Among them are;

•    Selective inhibition of methane formers by chloroform, carbon tetra-
     chloride, limited oxygenation, adjustment of redox potential, etc.
     in the acid digester (11)

•    Dialysis separation of the acid- and methane-forming cultures (12, 13)

•    Kinetic control of nonmethanogenic and methanogenic organism growth by
     adjustment of HRT5 reactor loading rate, and microbial and substrate
     SRT's by effluent recycling around each digester of a two-phase system
     (3, 6, 8, 9, 10).   Of the above techniques,  phase separation by kinetic
     control is expected to be superior because:

     a) It does not have the operating problems of membrane separation.

     b) It is free from the uncertainties of inhibitor action on both
        groups of digester organisms.

     c) The technique is successfully applied to two-phase digestion of
        soluble and solid substrates (3,9).

TWO-PHASE DIGESTION OF SOLUBLE SUBSTRATES

     The application of kinetic control to separate the acid-forming and
methane-forming phases of anaerobic digestion of soluble substrates was first
demonstrated by Pohland and Ghosh (3, 8), and later by Pohland and Massey  (14),
Ghosh et al. (9). Ghosh and Klass (15, 16), Heertjes and van der Meer  (17),
Smith et al. (18), Cohen et al. (19), and Ghosh and Henry  (6).

     Pohland and Ghosh (3) „ and Ghosh and Klass (15) studied the following
reaction systems to study the kinetic characteristics of acid-forming and
methane-forming organisms derived from a digested sewage sludge inoculum and
enriched in separate CSTR digesters:
A.   Nutrients + glucose           10   * volatile acids + C°2

B.   Nutrients + glucose continuous-digester „ volatile ac±ds + co
                 0
                            acidxf icatxon
                   , . . ,    .  ,  f    T, continuous-digester ^ ,,„   , rn
C.   Nutrients + volatile acids from B - methanatlo£ - -** CH4 + C02
     t-i         j         continuous -digester ^ _     pn
D.   Nutrients + acetate    methanatiog - ^ CH4 + C02
Kinetic constants derived from these digestion data are presented in Table 1.
The kinetic information is used to project the performance characteristics
of the digestion phases  as functions of such control variables as detention
time, feed substrate concentration, and loading rate.  The parameter selected
for evaluation of process performance is substrate conversion rate per unit
culture volume, R9 given by Equation 1 below!
                                      934

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        Table 1.   Kinetic Constants   for Mesophilic (37°C)  .Acidogenic
           and Methanogenic Cultures  Developed on Soluble Substrates.
                                                Methane Formers
Kinetic
Constants
- , -1
y , day
K, mg/£
Y
Acid Formers £
on Glucose Si
Batch
7.2
400 (glu)
0.15
Continuous
30.0
23 (glu)
0.17
lixed Volatile Acid
ibstrate From Glucose
(Continuous)
3.4
600 (acetate)
_-
Acetate
(Semicontinuous)
0.49
4200 (acetate)
0.28
"Kinetic constants shown here are the maximum specific growth rate, y f the
 saturation constant, K, and the growth yield, Y.
                                                                          [1]
                               ( y 9 - 1)
where
     S  = feed substrate concentration,
      o

     e  = IIRT.

     Figure 6 shows that detention times for maximized acidification of glucose
and methanation of acetate differ greatly from each other, and optimized high-
rate glucose digestion is not expected in a single-stage mixed-phase conven-
tional digester.  However, a two-phase system in which CSTR-type acid and
methane digesters are operated at IIRT's of 3.6 hours and 3 days can, in
theory, result in a maximum glucose-to-methane conversion rate.  Substantial
reduction in these HRT's could be obtained by utilizing reactor designs that
provide for maintenance of long SRT's (10).

     Various reactor designs, differing from the CSTR digesters initially em--
ployed by Pohland and Ghosh (3) and Ghosh and Klass (15), were studied by
other researchers.  Cohen et al. (19) experimented with a two-phase system
consisting of a CSTR acid-phase reactor and a plug-flow type upflow methane
digester with a built-in settler to conduct anaerobic digestion of glucose.
The cell yield coefficient for acid-phase digestion of glucose at 30°C was
0.11, compared with a yield coefficient of 0.17 at 37°C reported by Ghosh (20)
and Ghosh and Pohland (21).  Ethanol, acetateP propionate, butyrate, formate,
lactate, carbon dioxide,and hydrogen were the main products of acidogenesis.
Butyrate v?as produced in the largest concentrations, followed by acetate.
The acidogenic reaction products were gasified in the upflow methane digester
to produce head gases having 84.3 mol % methane and 15.7 mol % CO .
                                       935

-------
     Ghosh (22) , and Ghosh and Henry (6) operated a CSTR acid-<-phase and an
upflow packed-bed methane digester with real soft-drink bottling waste,, and
demonstrated that a two-phase digestion process could be operated at about 7
times the loading rate and one-half the HRT of the conventional process and
still obtain the same methane production as and a slightly higher COD reduction
than the conventional process (Table 2).  An important advantage of the

              Table 2.  High-Rate and Two-Phase Mesophilic (35°C)
                    Digestion of Soft^Drink Bottling Waste.
                                   Conventional
                                    High Rate

                                       0.04

                                       15

                                       10.3

                                       61.1

                                       0.4



                                       72

                                       84

                                       198
Loading, Ib VS/ft -day

HRT, days

Gas Yield, SCF/lb VS added

Methane Content, %

Gas Production Rate, vol/vol-day

Digestion Efficiencies, %

     VS Reduction

     COD Reduction

Digester Volume for 20,000 Ib/day
TS Load, 1000 ft3

Net Energy Production

     106 Btu/day

     Percent of Total Production
Two Phase
Acid
Phase
1.0
2.2
1.02
0.2
1.03
Methane
Phase
*
0.4
5.2X
9.44
70.5
3.68
Overall
0.3
7.4
9.76
63.1
2.90
22
44
64

96

66
                                       46,3

                                       37
                     80

                     64
 Loading and HRT of the upflow filter were calculated on the basis of the
 gross volume of the packed bed.

two-phase process was that gases from the methane phase had a significantly
higher methane content than those of the conventional digester.  Two-phase
operation allowed the total digester volume (and associated capital and
operating costs) to be reduced by 67% and the net energy production to be
increased by more than 73% relative to those of the conventional process.
Also, while the conventional high-rate digester failed at an HRT of 10 days
and a feed COD concentration of 26,000 mg/£, the two-7phase crocess exhibited
stable and efficient performance at a system HRT of 7.4 days and a feed COD
concentration up to 45,000
                                      936

-------
     Heertjes  and van der Meer  (17)  also  conducted  two^-phase  digestion  of
 saccharose  and sodium acetate in an  upflow digester with  an internal  settler
 built  at  the top (effluent end) of this digester.   High conversion efficiencies
 were obtained  at 3- to 6-hour residence time and a  relatively low loading
 (0.12  Ib  TOC/ft -day).  A two-reactor two-phase system exhibited increased
 stability at higher loadings up to 0.74 Ib TOC/ft3-day.

     Smith  et  al. (18) operated a packed-bed mesophilic (37°C) upflow methane
 digester  ("anaerobic filter") with solids-free acidic substrates derived
 from animal wastes.  Satisfactory acid-phase digestion could  not be developed
 with this waste.   Methane digester gas production rates from  0.24 to  a high
value of  2.77 volume/digester volume-day were observed at hydraulic retention
times of  40.5  to 1.1 days.

     In a recent study, Pipyn et al,  (23) investigated anaerobic digestion of
 distillery  wastewaters (>vLO,000 mg/£ COD) in a two-phase pilot plant  consisting
 of a 36-m3  CSTR acid-phase digester  and a 5-m3 upflow methane-phase digester.
The acid-phase was operated at 42°±2°C at an KRT of 16 to 72  hours, while the
methane-phase  digester was maintained at  39°±2°C and an HRT of 14 hours.
Overall COD and BOfi (biochemical oxygen demand) reductions of 84 percent and
 92 percent  were obtained.  The methane digester gases had a methane content
 of 75±3mol percent.

TWO-PEASE DIGESTION OF SOLID SUBSTRATES

     Ghosh  et  al. (9), and Ghosh and Klass (15) first demonstrated the  feasi-
bility of separating the acid and methane phases of anaerobic digestion of a
particulate feed (activated sludge) by kinetic control.  Satisfactory acid-
phase digestion occurred at detention times of 10 to 24 hours  and high
loadings  of 2  to 5 Ib VS/ft3-day.   Acidogenesis occurred at an oxidation-
reduction potential (EC) of —240 mV and a pH of 5.7, compared  to --400 mV and
 7.0 for methane formers.   Kinetic constants determined for acidogenesis of
activated sludge and biomethanation of acetate, which was the primary substrate
for methanogens,  are reported in Table 3.

               Table 3,   Kinetic Constants for Mesophilic (37°C)
                Two-Phase Digestion of Chicago Activated Sludge.

  Kinetic Constants   Acidogenesis of S_ludge   Biomethanation  of Acetate

      y , day'1           3.84                      0.49

      K,  g/i              4.3 (as  VS)               4.2 (as acetate)

      Y                   0.4                       0.28

Figure 7, developed from the above kinetic constants, shows that with a con-
centrated (5 wt percent VS) sludge feed, maximum acidogenesis and methanation
rates occurred at HRT's of 0.75 and 3 days, respectively, indicating  that
high-rate conversion of sludge to methane could be  achieved in a two-phase
system having an overall HRT of about 4 days.  These figures  also indicate
                                     937

-------
that the substrate conversion rate decreases and the HRT for maximum conversion
rate increases substantially as the system sludge feed concentration decreases-
this means that the HRT of the overall two-phase system increases significantly
as the system feed becomes more and more dilute.  Thus, for dilute feeds, a
two-phase process may not be as superior to the conventional process as it is
for concentrated feeds.

     Two-phase mesophilic digestion of 1.7 to 2.5 weight percent VS Chicago
sludge at an overall HRT of 6.9 to 7.7 days exhibited an average methane yield
of 4.3 SCF/lb VS added and a VS reduction of 40 percent (9) compared with
3.5 SCF/lb VS added and 34 percent observed during conventional digestion of
this sludge at an HRT of 14 days.  The methane content of the conventional
digester gases was 60 mol percent compared with 70 percent in the head gases
of the methane-phase digester.

     Eastman and Ferguson (24) conducted acid-phase digestion of primary sewage
sludge at detention times of 9 to 72 hours, and concluded that hydrolysis of
the solid sludge particles was the rate-dimiting step of the overall acidogenic
phase.  Lipids were not biodegraded, and 50 percent of the non-lipid COD of
primary sludge was solubilized.  Acidogenic sludge was difficult to settle.
Hydrogen evolution occurred at the minimum detention time of 9 hours.  Volatile
acid production and distribution of acid species in the effluent appeared to
be influenced by the reactor pH.   Brown (25) indicated that hydrolysis of
particulate substrate was favored at an acidic pH (pH 6), and methane fermenta-
tion of the acid-digestion products was better at an alkaline pH (pH 7.5).
Detailed investigation of the pH effect was not conducted to delineate the
pi! optima, however.  The methane digester gases contained 80 mol percent methane.

     Norrman and Frostell (26) conducted mesophilic (33°C) two-phase digestion
of a semisolid synthetic feed (blended dog food) in a laboratory system com-
prised of a completely mixed acid-phase digester and a packed-bed upflow
methane digester.   The acid digester was followed by a 500-ml gravity settler,
the supernatant from which was fed to the packed-bed methane digester.  Acid
digester pH was low (pH 4).   Solid-liquid separation was a problem with
the acid-digester effluent,   The overall system was operated at detention
times of 2.7 to 12.1 days and low loadings of 0.026 to 0.14 Ib VS/ft3-day.  A
long start-up time was required for the anaerobic filter.  The methane digester
gases contained 65 to 80 mol percent methane.   Like Norrman and Frostell.
Therkelsen and Carlson (27)  also investigated the two^-phase digestion chai ac-
teristics of dog food, but at a thermophilic temperature of 50°C.  The per-
formances of completely mixed and plug flow acid digesters were compared.
Surprisingly, lactate was the major acidic product.   The pH of the acid
digester dropped to 4.  Grease and organic nitrogen were not reduced signifi-
cantly.   One interesting observation was that acid production in a plug-flow
acid digester was much higher than that in the complete-mix reactor.  At the
test loadings (0.37 to 0.62 Ib VS/ft3-day) and detention times (4.3 to 7.5
days), two-phase thermophilic digestion of dog food was slightly better than
thermophilic conventional digestion.

     Keenan (28) conducted two-phase digestion of simulated solid waste
(Purina Dog Chow)  at 22° and 48°C.  The acidr-phase digester had relatively
                                      938

-------
 long  detention  times of 4.5  and 6 days: the methane digester had a detention
 time  of  10 days.  Acid digester gases contained mainly CC^ and a small amount
 of hydrogen.  Gases from the methane digester had 80 mol percent methane.  The
 acid  digester effluent had 13,000 to 14,000 mg/i of volatile acids.  There was
 no significant  difference in acid conversion efficiencies at 22°C and 48°C.
 The two-phase process provided more stability than the conventional mixed-
 phase high-rate process.

      In  contrast  to the two-reactor systems studied by most researchers,
 Johnson  (29) found evidence  of separation of the acidogenic and methanogenic
 phases during anaerobic fermentation of pig excrement and biomass leachate in
 a four-stage system.  The two-phase multi-stage process was superior to
 conventional high-rate digestion.

 BENEFITS OF TWO-PHASE DIGESTION

      Analysis of  the laboratory and pilot plant research data presented above
 shows that a multi-stage two-phase process evolves naturally when anaerobic
 digestion is conducted at high loadings and short HRT's in the interest of
 enhanced substrate conversion and gasification rates, reduced plant capital
 cost, and increased net energy production efficiency.  Investigators of the
 two--phase digestion process presented ample experimental evidence to indicate
 that  this advanced digestion process is potentially far superior to the
 conventional "high-rate" digestion process.

      The feasibility of phase separation by kinetic control has been demon*-
 strated for both soluble and solid substrates by several authors.  Acid-phase
 digestion can be conducted at residence times as low as 3 to 6 hours for
 soluble organics, and 9 to 24 hours for particulate organic material.   With
 proper process  design,  the overall two-phase system could be operated at
 residence times of 2 to 5 days, a substantial improvement over conventional
high-rate digestion conducted at residence times of about 12 to 20 days.

      In summary, the two-phase process has the following demonstrated and
potential benefits;

 •    Capability to optimize the environment and operating conditions for each
     digestion phase

•    Maximization of the overall substrate conversion rate per unit culture
     volume without  sacrificing conversion efficiency

•    Decreased digester volume, and plant capital and operating costs

•    Improved mixing in low-residence time digesters

•    Higher methane  content (up to 85 mol percent)  of the final product gas

•    Enhanced net energy production efficiency

•    Reduced nitrogen  content in the final product gas owing to increased
                                      939

-------
     denitrification of the feed in the acid digester

•    Increased process reliability owing to separation of the sensitive meth-
     ane bacteria and their protection from environmental shocks of sudden
     bursts of acid production, pH drops, and direct exposure to inhibitors.

PROBLEMS AND RESEARCH NEEDS

     A careful consideration of the work of various investigators indicates
that several potential problems including inefficient acetate formation,
substrate inhibition in methane—phase digestion, retarded digestion of such
substrate components as lipids and certain nitrogenous compounds could arise
during two-phase digestion.  Considerable fundamental research should be
undertaken to alleviate these problems and to develop an understanding of the
behavior of each microbial digestion phase in response to manipulation of
important fermentation parameters, operating modes, and reactor design.

REFERENCES

1.   11. P. Bryant, in Microbial- Energy Conversion, H. C. Schlegel and
     J. Earned, Eds. (Pergamon Press, Oxford, 1977), pp. 107-117.

2.   D. R. Omstead, T. H.  Jeffries, R. Naughton, and H. P, Gregor, in
     Biotechnology and Bioengineering Symp. No^ 10, C. D. Scott, Ed.
     "(John Wiley, New York, 1979), pp. 247-2^8.

3.   F. G. Pohland and S.  Ghosh, "Developments in Anaerobic Treatment
     Processes," Biotechnol. & Bioeng. Symp. No. 2, 85-106; In Biol. Waste
     Treatment, R. P. Canale (Ed.), Wiley Interscience Publishers, New York,
     57 Y. (1971).

4.   Fisher, J. A., et al., "Pilot Demonstration of Basic Designs for
     Anaerobic Treatment of Petrochemical Wastes," Chem. Eng. Progr. Symp.
     Ser., Am. Inst. of Chem. Engr., 485 (1970).

5.   P. L. McCarty, "Anaerobic Waste Treatment Fundamentals- I. Chemistry and
     Microbiology," Public Works, 95_, 9, 107 (1964).

6.   S. Ghosh and M, P. Henry, "Stabilization and Gasification of Soft-Drink
     Manufacturing Waste by Conventional and Two-Phase Anaerobic Digestion."
     Paper presented at the 36th Annual Purdue Industrial Waste Conference,
     West Lafayette, Indiana, May 12-14  (1981).

7.   H. E. Babbitt and E.  P. Baumann, Sewerage and Sewage Treatment, 8th
     Edition, John Wiley & Sons, New York, 1964.

8.   F. G. Pohland and S.  Ghosh, "Developments in Anaerobic Stabilization of
     Organic Wastes — The Two-Phase C on cep t,a En vi r on, Letters , !_,  4,  225
     (1971).
                                      940

-------
9.   S. Ghosh et al. ., "Anaerobic Acidogenesis of Sewage Sludge," Jour. Water
     Pollut. Control Fed. _47, 1, 30  (1975).

10.  S. Ghosh, '"Kinetics of Acid-Phase Fermentation in Anaerobic Digestion."
     Paper presented at the Third Symp. on Biotechnol. in Energy Prod, and
     Coservation, Gatlinburg, Tenn., May 12-15, 1981.

 11. F. D. Schaumburgh and E* J, Kirsch, "Anaerobic Simulated Mixed Culture
     Systern." App1.  Microblpl.- 14, 761 (1966).

12.  J. A, Borchardtf nAnaerobic Phase Separation by Dialysis Technique,"
     Anaerobic Biological Treatment Processes, ACS Advances in Chemistry
     Series 105 and  108, Washington, D.C., 1971.

13.  J. A. Borchardt, "A Discussion/' Proc, Third Intl. Conf, on Water Pollut.
     Res._, 1, 309 (1967).                             ~"      —      —-

14.  F. G. Pohland and M. L.  Massey, "An Application of Process Kinetics for
     Phase Separation of the Anaerobic Stabilization Process," Progr. Wat.
     Techno!. 7, 1,  173-189 (1975).                               " "

15.  S. Ghosh and D. L.  Klass, "Two-Phase Anaerobic Digestion," Proc. Biochem.
     1J3, 15-24 (1978) April.                                     ""*"""

16.  S. Ghosh and D. L.  Klas's, "Two-Phase Anaerobic Digestion," U.S. Patent
     4,022,665, May  10 (1977).

17.  P. M. Heertjes  and R.  R.  van der Meer, "Comparison of Different Methods
     for Anaerobic Treatment of Dilute Wastewaters."  Paper presented at
     Purdue Ind. Waste Conf.,  West Lafayette, Ind., May 8-10 (1979).

18.  R. E. Smith, et al. , "Two-Phase Anaerobic Digestion of Poultry Waste,1'
     Paper No.  75-4544,,  presented at the ASAE Winter Meeting, Chicago,
     December 15-18  (1975).

19.  A. Cohen,  et al., "Anaerobic Digestion of Glucose With Separated Acid
     Production and  Methane Formation," Wat;. Res,  _13, 571-580 (1979).

20.  S. Ghosh,  ''Kinetics of Substrate Assimilation and Product Formation in
     Anaerobic Mixed Culture Systems."  Paper presented at the Symp. on Appli-
     cation of Cont. Culture Theory to Biol. Waste Treatment Processes, 162nd
     Natl. Meeting of ACS,  Washington, D.C., September 1971.

21.  S. Ghosh and F. G.  Pohland, "Kinetics of Substrate Assimilation and
     Product Formation in Anaerobic Digestion," Jour. Wat. Pollut. Control
     Fed._, 46,  4, 748-59 (1974).

22.  S. Ghosh,  "Alleviation of Environmental Problems of Waste Disposal With
     Production of Energy and Carbon Dioxide."  Paper presented at the 28th
     Annual Meeting, Soc. of Soft Drink Technologists, Colorado Springs,
     Colorado,  August 26-29  (1981).
                                     941

-------
23.  P. Pipyn, W.  Verstraete, and J.  P.  Ombregt, "A Pilot Scale Anaerobic
     Upflow Reactor Treating Distillery  Wastewatersrv  Biotechno1.  Letters,
     1, 495-500 (1979).

24.  J. A.  Eastman and J.  F.  Ferguson, "Solubilization of Particulate Organic
     Carbon During the Acid Phase of  Anaerobic Digestion."  Paper presented
     at the 51st Annual Conference, Water Pollution Control Federation,
     Anaheim, Calif., October 3 (1978).

25.  A. H.  Brown,  "Bioconversion of  Solar Energy,"1 Chemtech. ,  434-37 (1975)
     July.

26.  J. Norrman and B. Frostell, "Anaerobic Waste Water Treatment in a Two-
     Stage  Reactor of a New Design."   Paper presented at Purdue University
     Industrial Waste Conference, West Lafayette, Ind. , May 10, 1977.

27.  H. II.  Therkelsen and  D.  A. Carlson, "Thermophilic Anaerobic Digestion of
     a Strong Complex Substrate." Paper presented at the 50th Annual Conf-
     erence,Water Pollution Control Federation, Philadelphia,  October 2-7,
     1977.

28.  J. D.  Keenan, "Two-Stage Methane Production From Solid Wastes."  Paper
     No. 74-WA/Ener-ll presented at  the  ASME Winter Annual Meeting, New York,
     November 17-22, 1974.

29.  A. L.  Johnson, "Final Report on  Research in Methane Generation,"
     U.S.  Office of Sci, and Techno1.„ Work performed under Contract No.
     AID/ta-G-1278, Project No. 931-17-998^-001^73, El Segundo, Calif., The
     Aerospace Corporation. September 1976,
                                      942

-------
   AMMONIA
^SULFIDES
              CARBOHYDRATE
                 PROTEIN
                    FAT
Figure 1.  Reaction Steps  in Anaerobic Digestion.

-------
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         76     80      85      9O      95      100      105

                                   ACCUMULATIVE TIME, days
                                                      110
                                                              115       120

                                                                    B8I0509I „
Figure 3.  Response of a Continuous-Flow High-Rate  Soft-Drink Waste Digester
              to Increased Loadings  and Reduced Detention Times:
                     Development  of  an Acid-Phase Culture.
                                      945

-------
                                                   CH4 YIELD,
                                                 SCF/lb VS added
                6     8    10   12    14    16    18
                  SLUDGE  SOLIDS,  wt %
20   22   24

      A8I09I930
Figure  4.  Dependence of the Net Energy Production Ratio on the
    Feed Sludge Solids Concentration for Mesophilic (35°C)
   Digestion of a  60-wt Percent VS-Content  Feed at a Loading
        Rate of 0.1 Ib VS/ft3-day (The feed slurry is
           assumed to have a temperature of 15°C).
                            946

-------
LJ
\
 Q.
LJ
2.4

2.2

2.0

 1.8

 1.6

 1.4

 1.2

 1.0

0.8

0.6

0.4

0.2

  0
       0.01
                                                              CH4 YIELD,
                                                            SCF/lbVS added
                              I
                       I
                 0.05   O.I
0.5
1.0
                       LOADING RATE,lbVS/ft3-day
5     10

 A8I09I93I
       Figure  5.  Dependence of the Net  Energy Production Ratio on the
         Digester Loading Rate for Mesophilic  (35°C) Digestion of a
            60-wt Percent VS-Content Feed  (The feed slurry has a
        3-wt percent solids concentration  and a temperature of 15°C).
                                    947

-------
      300
                                                              I 5% GUI FEED
                                                              	_
                                                              41% GLU FEED
    14
    12
  I »
  o
         0 0.1  0.2 0.3 04  05 06  0.7  0.8 0.9  Ifl  I.I  1.2  13  14   15  1.6  1.7  I.B  1.9 2.0

                           	DETENTION TIME, days	ASIWBM
                  -3 DAYS
                                                 CONDITIONS
                                                 A'0.49 DAY'1
                                                 K,=4.2g//
                        4.5 DAYS
                                                     -5%HOAc FEED
                                           0.5% HOAc FEED
                                                    ,l%HOAcFEED
      0      2      4      6     6      10     12      14      16      IB     20
                               DETENTION TIME, days                     A81O9I932
Figure  6.   Glucose  Acidification and Acetic Acid Methanation Rates
   Per  Unit  Acid  Digester  Volume as Functions  of Detention Time
  and Substrate Concentration Under Mesophilic (37°C) Conditions.
                                      948

-------
                                   8      10     12     14
                                  DETENTION TIME, days
16
       18     20

         A8I09I934
                                            0.5% HOAc FEED
                                                      i% HOAC FEED
                           6      8    x  tQ     .12     14
                              '  DETENTION TIME.'days.
                                                                     A809I932
Figure  7,  Sewage Sludge Acidification  and Acetic Acid Methanation Rates
    Per Unit Acid Digester Volume as Functions  of Detention Time and
        Substrate Concentration  Under Mesophilic (37°C) Conditions.
                                      949
                                                       ft US GOVERNMENT PRINTING OFFICE. 1984 - 759-102/10684

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