EPA 600/9-77-027
PROCEEDINGS
5th UNITED STATES/JAPAN
CONFERENCE ON
SEWAGE TREATMENT TECHNOLOGY
TOKYO, JAPAN
APRIL 18-22, 1977
U.S. ENVIRONMENTAL PROTECTION AGENCY
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/9-77-027
DECEMBER 1977
PROCEEDINGS
FIFTH UNITED STATES/JAPAN CONFERENCE ON
SEWAGE TREATMENT TECHNOLOGY
APRIL 18-22, 1977
TOKYO, JAPAN
OFFICE OF INTERNATIONAL ACTIVITIES
OFFICE OF WATER AND HAZARDOUS MATERIALS
WASHINGTON, D.C. 20460
OFFICE OF RESEARCH AND DEVELOPMENT
WASHINGTON, D.C. 20460
CINCINNATI, OHIO 45268
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
CINCINNATI, OHIO 45268
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DISCLAIMER
These Proceedings have been reviewed by
the U.S. Environmental Protection Agency
and approved for publication. Approval
does not signify that the contents necessarily
reflect the views and policies of the U.S.
Environmental Protection Agency, nor does
mention of trade names or commercial products
constitute endorsement or recommendation for
use.
11
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FOREWORD
Environmental improvement is a worldwide need. Maintaining clean
water supplies and managing municipal and industrial wastes is a vital
element of a quality environment.
The participants in the United States-Japan cooperative project
on sewage treatment technology have completed their fifth conference.
These conferences, held at 18-month intervals, give the scientists and
engineers of the cooperating agencies an opportunity to study and com-
pare the latest practices and developments in the United States and
Japan. These Proceedings of the Fifth 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 any nation of the world
which may wish to have it.
las M. Co
inistrator
Washington, D.C.
Ill
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CONTENTS
FOREWORD
JAPANESE DELEGATION vi
UNITED STATES DELEGATION vii
JOINT COMMUNIQUE
JAPANESE PAPERS
UNITED STATES PAPERS
v
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JAPANESE DELEGATION
K. INOMAYE
Team Leader - Director, Department of Sewerage
& Sewage Purification, Ministry of Construction
S. TAKAHASHI
Head, Planning Division, Department of Sewerage
& Sewage Purification, Ministry of Construction
DR. M. KASHIWAYA
Head, Water Quality Control Division, Public Works
Research Institute, Ministry of Construction
T. HAYASHI
Head, Water Quality Control Division, Water Quality
Bureau, Environmental Agency
DR. A. SUGIKI
Head, Research and Technology Development Division,
Japan Sewage Works Agency
H. FUJII
Senior Advisor, Sewerage Bureau, Tokyo Metropolitan
Government
K. TANI
Head, Construction Division, Sewage Works Bureau,
Osaka City Office
S. MIYAKOSHI
Head, Construction Division, Sewage Works Bureau
Yokohama City Office
DR. T. KUBO
Co-Chairman - Vice President, Japan Sewage Works
Agency
VI
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UNITED STATES DELEGATION
FRANCIS M. MIDDLETON
General Chairman of the Conference and Team Leader
Senior Science Advisor/
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
DR. CARL A. BRUNNER
Chief, Systems & Engineering Evaluation Branch
Wastewater Research Division
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
DR. ROBERT L. BUNCH
Chief, Treatment Process Development Branch
Wastewater Research Division
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
ROBERT S. BURD
Chief, Water Division, Region X
U.S. Environmental Protection Agency
Seattle, Washington 98101
FRANKLIN D. DRYDEN
Head, Technical Services Department
Los Angeles County Sanitation Districts
Whittier, California 90607
WILLIAM J. LACY
Principal Engineering Advisor
Office of Research & Development
U.S. Environmental Protection Agency
Washington, D.C. 20460
J. LEONARD LEDBETTER
Director, Water Protection Branch
Department of Natural Resources
Environmental Protection Division
Atlanta, Georgia 30334
THOMAS P. O'FARRELL
Sanitary Engineer, Water Program Operations
Office of Water and Hazardous Materials
U.S. Environmental Protection Agency
Washington, D.C. 20460
vii
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UNITED STATES AND JAPAN
DELEGATES TO THE 5TH CONFERENCE
U.S. DELEGATES CONFERRING ON TREATMENT TECHNOLOGY
WITH MR. R. OKUDA, GOVERNOR OF NARA PREFECTURE
Vlll
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-t*
../ r-i
UNITED STATES TEAM INSPECTS
DEEP TUNNEL STORMWATER CONTROL PROJECT
OSAKA, JAPAN
UNITED STATES TEAM TOURS
ADVANCED WASTE TREATMENT PILOT PLANT
KYOTO, JAPAN
IX
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VIEWING A NEW SEWAGE TREATMENT PLANT
NARA, JAPAN
PILOT PLAIT. KYOTO
IM ,',
! '• ,
•i
DR. M. KASHIWAYA AND DR. K. MURAKAMI
MINISTRY OF CONSTRUCTION, JAPAN
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JOINT COMMUNIQUE
FIFTH US/JAPAN CONFERENCE ON
SEWAGE TREATMENT TECHNOLOGY
TOKYO/ JAPAN APRIL 28, 1977
1. The Fifth United States - Japan Conference on Sewage Treatment
Technology was held in Tokyo, Japan from April 26 ~ 28, 1977-
2. The United States Delegation headed by Mr. F. M. Middleton, Senior
Science Advisor, Municipal Environmental Research Laboratory, U.S.
Environmental Protection Agency, Cincinnati, Ohio, was composed of
six USEPA officials and two local government officials.
3. Mr. K. Inomaye, Director, Department of Sewerage and Sewage Purifi-
cation, Ministry of Construction, was Head of the Japanese Delegation,
other delegation members were three national government officials, two
Japan Sewage Works Agency officials and three local government officials.
4. The Chairmanship for the Conference was shared jointly be Mr. F. M.
Middleton and Dr. T. Kubo, Vice President, Japan Sewage Works Agency.
5. Prior to the Conference, the United States Delegation visited the Toba
Sewage Treatment Plant, Kyoto; the Advanced Waste Treatment Pilot Plant,
Otsu; the takagi Tannery Wastewater Treatment Plant, Himeji; the Yamato
River Purification Center, Nara; the Kawamata Sewage Treatment Plant and
the Nakahama Sewage Treatment Plant, Osaka; the Morigasaki Sewage Treatment
Plant, Tokyo and the South Sewage Treatment Plant, Yokohama. Each field
visit involved the subject matter discussed in the Japanese side papers
presented at the Conference so that the Conference may promote vigorous
discussion more in detail.
6. During the Conference the United States Delegation presented a series
of papers on the topics of Control of Non-point Source Pollution, Use
of New Technology in the EPA Construction Grant Program, Georgia's Water
Quality Control Program, Federal-State-Regional Participation in the
Development of a Wastewater Management Plan, Regional Domestic Waste-
water Management, Urban Run-off Pollution Control Technology, Wastewater
Reuse, Industrial Wastewater Pretreatment and Joint Treatment, Criteria
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and Assessment of Waste Treatability, Biological, Nitrogen and
Phosphorus Control, and Water Reclamation Technology.
7. The Japanese side described Industrial Wastewater Control into
Public Sewers, Recent Topics in Water Pollution Control in Japan,
Storm and Combined Sewer Overflows, Regeneration of Granular Acti-
vated Carbon, Deep Aeration Tanks, Upgrading Existing Plant by
Chemical Addition to Aeration Tanks, Rapid Sand Filtration Process
for Tertiary Purpose. Papers on Sludge Disposal and Automatic Water
Quality Monitoring Equipment were presented at the Conference as an
interim report of Joint Research Works between the United States and
Japan under the Joint Agreement of the US/Japan Conference on Sewage
Treatment Technology.
8. Each presentation was followed by lively discussions from both sides.
9. Recent personnel exchanges include a short visit to Japan by Mr. J. T.
Rhett and Mr. M. B. Cook, USEPA, Washington, D.C. to investigate insti-
tutional structures in the field of water pollution control in Japan.
Mr. F. M. Middleton visited Japan to discuss progress of joint research
works and the program for the Fifth Conference. Mr. K. Tanaka and Mr.
S. Hiromoto, Japan Sewage Works Agency, are planning to spend several
months in the United States in 1977 to study plant design and operation,
and urban run-off pollution control technology respectively.
10. In addition to the Conference the Seminar was opened to about 200
members of the Japan Sewage Works Association on the subjects of the
United States presentations during the Conference.
11. The Conference concluded that the technology exchange program including
the Conference was fruitful to both sides in exchanging knowledge and
experience and the Delegations agreed to seek to explore more effective
cooperation in the field of research works and that the personnel exchange
program should be continued.
12. It was proposed by the United States side that the Sixth Conference
should be held in the United States, about October 1978.
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FIFTH US/JAPAN CONFERENCE
ON
SEWAGE TREATMENT TECHNOLOGY
PAPER NO, 1
RECENT PROGRESS IN INDUSTRIAL WASTEWATER
CONTROL DISCHARGED INTO PUBLIC SEWER
RECENT TOPICS IN WATER POLLUTION CONTROL
IN JAPAN
APRIL 26-28, 1977
TOKYO, JAPAN
MINISTRY OF CONSTRUCTION
JAPANESE GOVERNMENT
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RECENT PROGRESS IN INDUSTRIAL WASTEWATER CONTROL
DISCHARGED INTO PUBLIC SEWER 5
S. Takahashi, Ministry of Construction
RECENT TOPICS IN WATER POLLUTION CONTROL IN JAPAN 28
T. Hayashi, Environmental Agency
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RECENT PROGRESS IN INDUSTRIAL WASTEWATER CONTROL
DISCHARGED INTO PUBLIC SEWER
1. Reasons for Revision of the Sewerage Law 6
2. Summary of Revision in the Sewerage Law 8
2.1 Introduction of Direct Penalty System 8
2.2 Introduction of a Prior Checking System 16
2.2.1 Notification of Construction of Specified Facilities 16
2.2.2 Orders for Modification of Plans 17
2.3 Introduction of Improvement Order System 17
3. Present State of Controls on Factory Effluent 17
3.1 Present State 17
3.1.1 Number of Specified Factories 17
3.1.2 Types of Specified Factories 19
3.1.3 Installation State of Pre-Treatment Facilities 22
3.1.4 Surveillance on Factory Effluent ; 22
3.2 Aid System for Construction of Pre-Treatment Facilities 25
3.3 Publication of Guidance Manual 25
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RECENT PROGRESS IN INDUSTRIAL WASTE WATER
CONTROL DISCHARGED INTO PUBLIC SEWER
1. REASONS FOR REVISION OF THE SEWERAGE LAW
The public sewerage system is indispensable as a facility not only for the im-
provement of the living environment but also for the maintenance of the water
quality of the public water bodies, and therefore the improvement of the public
sewerage system is urged. However, such an improvement would not fully serve its
purpose, if the effluent from households and factories did not flow into the public
sewerage system and remained on the ground surface or continued to run along the
conventional open sewers.
For this reason, the Sewerage Law provides that as the public sewerage system
is opened for public use, all sewage in the relevant drainage area must be discharged
into the public sewerage system with the exception of the effluent whose direct dis-
charge into the public water bodies is approved by the general manager of the
public sewerage system. The Law also provides that the water quality of the effluent
discharged from the public sewerage system to rivers and other public water bodies
must meet technical standards (Table 1) as specified under Article 8 of the Sewerage
Law.
Therefore, it is the general principle that the following type of effluent dis-
charged from factories in the drainage area is treated at their source to meet certain
standards. The effluent subject to the treatment is one that could either disrupt the
functions of sewerage facilities or damage the facilities or one that could make it dif-
ficult for the water quality of the effluent discharged from the final treatment facili-
ties to meet technical standards as provided under Article 8 of the Law.
Table 1 Standards for Effluent Quality
^"~~~~-^-^^^ Item
Classification ~-^^_^
Treatment of sewage by high-rate
trickling filter process, modified
activated sludge process and other
processes with similar efficiency.
Treatment of sewage by high-rate
trickling filter process, modified
activated sludge process and other*
processes with similar efficiency
Treatment of sewage by sedimen-
tation process
Other
Hydrogen-Ion
Concentration
(Hydrogen
Exponent)
5.8-8.6
5.8-8.6
5.8-8.6
5.8-8.6
Biochemical
Oxygen Demand
(mg/£ in
five days)
Less than 20
Less than 60
Less than 120
Less than 150
Amount of
Suspended
Solids
(mg/fi)
Less than 70
Less than 120
Less than 150
Less than 200
No. of
Bacteria Coli
(No./cm')
Less than 3000
Less than 3000
Less than 3000
Less than 3000
Figures were calculated by the procedures provided for in the Ordinance of the Ministry of Construction and
the Ordinance of the Ministry of Health and Welfare.
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Table 1 (Continued)
Substances
Cadmium and Its Compounds (Cd)
Cyanide Compounds (CN)
Organic Phosphorus Compounds
(Parathion, Methyl Parathion, Methyl
Demeton and EPN only)
Lead and Its Compounds (Pb)
Chromium (VI) Compounds [Gr (VI) ]
Arsenic and Its Compounds (As)
Total Mercury (Hg)
Alkyl Mercury Compounds
PCB
N-hexane Extracts
Phenols
Copper (Cu)
Zinc (Zn)
Dissolved Iron (Te)
Dissolved Manganese (Mr.)
Chrome (Cr)
Fluorine (F)
Permissible Limits
0.1 mg/E
1 mg/6
1 mg/E
1 mg/C
0.5 mg/E
0.5 mg/E
0.005 mg/E
Not detectable1
0.003 mg/E
5 mg/E (mineral oil)
30 mg/E (animal and vegetable fats)
5 mg/E
3 mg/E
5 mg/E
10 mg/E
10 mg/E
2 mg/E
15 mg/E
In reference to controls on the inferior sewage discharged by factories or es-
tablishments that could disrupt the functions of sewerage facilities, damage them or
aggravate the effluent quality of the final treatment facilities, the Sewerage Law
before revision provided under Article 12 that the general manager of the public
sewerage system under relevant regulations could order factories and other establish-
ments to build pre-treatment facilities or take other necessary measures. Standards
for the installation of pre-treatment facilities were to be instituted by city, town or
village authoritie's regulations in accordance with the standards as prescribed by
Cabinet Order (Table 2).
In this case, the standards provided by the regulations were the minimum re-
quirements to maintain the structure and functions of the public sewerage system
and conform the water quality of the effluent to the technical standards provided
under Article 8 of the Law, and unduly obligations must not be imposed on the user
of the public sewerage system.
However, it was pointed out that under the Sewerage Law before revision,
guidance for the installation of sewage pre-treatment facilities tended to be delayed
due to the following reasons.
a. The general manager of the public sewerage system was obliged to order the
violator of the regulations to install pre-treatment facilities, but the penalty pro-
visions were not applied unless he disobeyed the order given. The Law had no pro-
visions for the so-called "direct penalty system" in which the violator of the regu-
lations is punished immediately upon the revelation of his violation.
b. The Law provided no prior checking system as to the construction or reno-
vation of facilities that could discharge inferior sewage.
7
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Table 2 Standards of Regulation Concerning
Installation of Pre-treatment Facilities
Substances
Temperature
pH
BOD
SS
N-hexane Extracts
Mineral Oils
Animal and Vegetable Fats
Consumption of Iodine
Phenols
Cyanide Compounds (CS)
Alkyl Mercury Compounds
Organic Phosphorus Compounds
Cadmium and Its Compounds Cd)
Lead and Its Compounds (Pb)
Chromium (VH Con^JoundSLCr (VI)j
Arsenic and Its Compounds (As;
Total Mercury (Hg)
Chrome (Cr)
Copper (Cu)
Zinc (Ziv)
Dissolved Iron (Fe)
Dissolved Manganese (Mn)
Fluorine (?)
PCB
Permissible
Limits
45° C
5-9
600 mg/e
600 mg/2
5 mg/2
30 mg/e
220 mg/2
5 mg/e
1 mg/e
ND
1 mg/C
0.1 mg/e
1 mg/C
0.5 mg/e
0.5 mg/C
0.005 mg/C
2 mg/B
3 mg/C
5 mg/e
10 mg/e
10 mg/e
15 mg/C
0.003 mg/e
With respect to sanitary sewage discharged from
facilities used for manufacturing and gas supplying
business, the standards can be tightened up to those
at the table below, if it is recognized that the total
amount of sanitary sewage from them is equivalent
to more than one-fourth of sanitary sewage to be
treated at the treatment facility, that it will not be
sufficiently diluted by other sanitary sewage before
reaching the treatment facility or that there is any
other justifiable reason.
Substances
Temperature
PH
BOD
SS
Permissible Limits
40° C
5.7-8.7
300 mg/C
300 mg/C
As a result, the Law was revised to improve on the above-mentioned points,
strengthen controls on the effluent from factories or establishments and thus con-
tribute to the maintenance of the water quality of the public water bodies.
2. SUMMARY OF REVISION IN THE SEWERAGE LAW
2.1 INTRODUCTION OF DIRECT PENALTY SYSTEM
Under the revised Sewerage Law, provisions less effective than the Water Pol-
lution Control Law were improved, and a new provision was introduced to prevent
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the discharge of the sewage whose water quality does not meet specified legal
standards. Violations, including accidental violations, are now subject to immediate
punishment on the revelation of their violations without taking supervisory action
for them. Thus the revised Law has adopted the so-called "direct penalty system."
This new provision, as in the Water Pollution Control Law, is applied to facto-
ries or establishments which operate specified facilities (as designated under the
Water Pollution Control Law as facilities that could discharge inferior waste water —
Table 3). But its application excludes kitchen facilities, washing facilities and
bathing facilities (not using water from hot springs) of hotel business and the final
sewerage treatment facilities.
Table 3 Specified Facilities
(1) MINING AND COAL WASHING
(a) ore separation facilities, (b) coal dressing facilities, (c) neutralization
and sedimentation facilities of mine water, (d) solids separation facilities
from water used for digging.
(l)-2 LIVESTOCK BREEDING
(a) pig shed facilities (excluding the facilities installed in the shed with the
total area of less than 50 m2)
(b) cattle shed facilities (excluding the facilities installed in the shed with the
total area of less than 200 m2)
(c) horse shed facilities (excluding the facilities installed in the shed with the
total area of less than 500 m2)
(2) MEAT PACKING AND POULTRY PROCESSING
(a) initial preparation facilities, (b) washing facilities, (c) cooking facili-
ties.
(3) SEA FOODS MANUFACTURING
(a) initial preparation facilities, (b) washing facilities, (c) dehydration
facilities, (d) screening facilities, (e) cooking facilities.
(4) CANNED AND FROZEN VEGETABLES AND FRUITS MANUFACTURING
(a) initial preparation facilities, (b) cleaning facilities, (c) pressing facili-
ties, (d) cooking facilities.
(5) MISO, SOY-SOURCE, EDIBLE AMINO ACID, GLUTAMIC ACID, VEGE-
TABLE SOURCES AND VINEGAR MANUFACTURING
(a) initial preparation facilities, (b) cleaning facilities, (c) boiling facili-
ties, (d) concentration facilities, (e) finishing facilities, (f) straining
facilities.
(6) WHEAT FLOUR MANUFACTURING
(a) washing facilities.
(7) SUGAR MANUFACTURING
(a) initial preparation facilities, (b) washing facilities, (c) filtration
facilities, (d) separation facilities, (e) refining facilities.
(8) BAKERY AND CONFECTIONARY
(a) bean-jam processing facilities.
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(c) pressing
(c) separation
(9) RICE CAKE AND MALT MANUFACTURING
(a) washing facilities.
(10) SOFT DRINK MANUFACTURING AND BREWERY
(a) initial preparation facilities, (b) cleaning facilities, (c) extraction
facilities, (d) straining facilities, (e) boiling facilities, (f) stilling
facilities.
(11) FEED STAFF AND ORGANIC FERTILIZER MANUFACTURING
(a) initial preparation facilities, (b) washing facilities, (c) pressing
facilities, (d) vacuum concentration facilities, (e) water bushing de-
odorization facilities.
(12) OIL AND FAT MANUFACTURING
(a) initial preparation facilities, (b) washing facilities,
facilities, (d) separation facilities.
(13) YEAST MANUFACTURING
(a) initial preparation facilities, (b) washing facilities,
facilities.
(14) STARCH MANUFACTURING
(a) soaking facilities, (b) washing facilities, (c) separation facilities,
(d) waste pits.
(15) DEXTROSE MANUFACTURING
(a) initial preparation facilities, (b) filtration facilities,
facilities.
(16) NOODLES MANUFACTURING
(a) boiling facilities.
(17) BEAN FOODS MANUFACTURING
(a) boiling facilities.
(-18) INSTANT COFFEE MANUFACTURING
(a) extraction facilities.
(19) TEXTILE INDUSTRY
(a) scouring facilities, (b) by-product processing facilities,
facilities, (d) finishing facilities, (e) silket machine,
facilities, (g) dyeing facilities, (h) chemical treatment facilities.
(20) WOOL SCOURING AND WASHING
(a) wool scouring and washing facilities, (b) carbonizing facilities.
(21) SYNTHETIC TEXTILE MANUFACTURING
(a) spinning facilities, (b) chemical treatment facilities,
facilities.
(22) CHEMICAL FINISHING OF WOODS
(a) wet barker, (b) chemical soaking facilities.
(23) PULP AND PAPER MANUFACTURING
(a) soaking, (b) wet barker, (c) chiper, (d) digester,
later for digester waster, (f) chip refiner and pulp refiner,
(c) refining
(c) soaking
(f) bleaching
(c) recovery
(e) accumu-
(g) bleaching
facilities, (h) paper mill, (i) cellophane paper mill, 0) wet fiber plate
facilities, (k) waste gas washing facilities.
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(24) FERTILIZER MANUFACTURING
(a) filtration facilities, (b) separation facilities, (c) water jet breaking
facilities, (d) waste gas washing facilities, (e) wet dust collector.
(25) SODIUM HYDROXIDE AND POTASSIUM HYDROXIDE MANUFAC-
TURING (MERCURY ELECTROLYSIS)
(a) electrolyte refining facilities, (b) electrolyzing facilities.
(26) INORGANIC PIGMENT MANUFACTURING
(a) washing facilities, (b) filtration facilities, (c) centrifuger (cadmium
and its compounds), (d) water flushing separate (erdigris), (e) waste gas
washing facilities.
(27) INORGANIC CHEMICALS MANUFACTURING EXCLUDING ITEMS OF
25 AND 26
(a) filtration facilities, (b) centrifuger, (c) sulfur dioxide gas cooling
and washing facilities (sulfuric acid), (d) washing facilities (activated
carbon and carbonated disulfur), (e) hydrochloric acid regenerating facili-
ties (silicate anhydrous), (f) reactor (cyanides), (g) absorber and sedi-
mentation facilities (iodines), (h) sedimentation facilities (saline magnesia),
(i) water flushing facilities (bariumates), (j) waste gas washing facilities,
(k) wet dust collector.
(28) ETHYLENE DERIVATES MANUFACTURING (CARBIDE PROCESS)
(a) wet ethylene generation facilities, (b) washing facilities and still (ace-
tate ester), (c) methyl alcohol still (polyvinyl alcohol), (d) still (acrylic
acid ester), (e) vinyl chloric monomer washing facilities, (f) chloroprene
monomer washing facilities.
(29) COAL TAR PRODUCTS MANUFACTURING
(a) sulwuric acid washing facilities of benzene relates, (b) waste pits,
(c) tar sodium fulfonate reactor.
(30) FERMENTATION INDUSTRY EXCLUDING ITEMS OF 5, 10 AND 13
(a) initial preparation facilities, (b) still, (c) centrifugal decanter,
(d) filtration facilities.
(31) METHANE DERIVATES MANUFACTURING
(a) still (methyl alcohol and 4-chloromethane), (b) refining facilities
(formaldehyde), (c) washing and filtration facilities (fione gas).
(32) SYNTHETIC PLASTIC MANUFACTURING
(a) filtration facilities, (b) water washing facilities (pigments or dye lake),
(c) centrifugal decanter, (d) waste gas washing facilities.
(33) SYNTHETIC PLASTIC MANUFACTURING
(a) condensation reactor, (b) water washing facilities, (c) centrifugal
decanter, (d) settling facilities, (e) cooling gas washer and still (florides
plastics), (0 diluent still (polypropylene), (g) diluent still (polyethy-
lene), (h) acid and alkali treatment facilities (polybutane), (i) waste gas
washing facilities, (k) wet dust collector.
11
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(34) SYNTHETIC RUBBER MANUFACTURING
(a) filtration facilities, (b) dehydration facilities, (c) washing facilities,
(d) latex concentration facilities, (e) sedimentation facilities (styrene-
butadiene, nitrile-butadiene and poly butadiene-gum).
(35) ORGANIC GUM CHEMICALS MANUFACTURING
(a) destination facilities, (b) waste gas washing facilities, (c) wet dust
collector.
(36) SYNTHETIC DETERGENT MANUFACTURING'
(a) acid washing and separating facilities, (b) waste gas washing facilities,
(c) wet dust collector.
(37) PETROCHEMICAL INDUSTRIES (CARBOHYDRATE AND ITS DERI-
VATES) EXCLUDING ITEMS FROM 31 TO 36 AND 51
(a) washing facilities, (b) separation facilities, (c) filtration facilities,
(d) distillation and rapid cooling facilities (acrylonitrile), (e) distillation
facilities (acetoaldehyde, eterphatalic acid, thylene diamine), (f) acid and
alkali treatment facilities (alkyl benzene), (g) distillation facilities and
sulphuric acid concentration facilities (iso-propyl alcohol), (iso-propyl
alcohol), (h) distillation and condensation reactor (alcohol), (i) gas
cooling and washing facilities (phalic acid anhydride), (J) acid and alkali
treatment facilities (cyclohexane), (k) methylalcohol distillation facilities
and acid, alkal treatment facilities, (1) steam condenser (ethylketone),
(m) methylalcohol recovery facilities and reactor (methy-m-acrytate mono-
mer), (p) waste gas washing facilities.
(38) SOAP MANUFACTURING
(a) initial preparation facilities, (b) salting out facilities.
(39) HYDROGENATED OIL MANUFACTURING
(a) alkali conditioning facilities, (b) deodorization facilities.
(40) FATTY ACIDS MANUFACTURING
(a) distillation facilities.
(41) PERFUMERY MANUFACTURING
(a) washing facilities, (b) extraction facilities.
(42) GELATINE AND GLUE MANUFACTURING
(a) initial preparation facilities, (b) lime soaking facilities, (c) washing
facilities.
(43) PHOTO SENSITIVE GOODS MANUFACTURING
(a) washing facilities.
(44) NATURAL RESIN MANUFACTURING
(a) initial preparation facilities, (b) dehydration facilities.
(45) WOODS CHEMICAL MANUFACTURING
(a) furfural distillation facilities.
(46) ORGANIC CHEMICALS MANUFACTURING EXCLUDING ITEMS FROM
28 TO 45
(a) water washing facilities, (b) filtration facilities, (c) concentrator
(hyrazide), (d) waste gas washing facilities.
12
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(47) PHARMACEUTICAL MANUFACTURING
(a) initial preparation facilities, (b) filtration facilities, (c) separation
facilities, (d) mixing facilities, (e) gas washing facilities.
(48) GUNPOWDER MANUFACTURING
(a) washing facilities.
(49) PESTICIDES MANUFACTURING
(a) mixing facilities.
(50) PEAGENT MANUFACTURING
(a) processing facilities.
(51) OIL REFINING INDUSTRY
(a) desalting facilities, (b) crude petroleum distillation facilities, (c) de-
sulfurization facilities, (d) washing facilities (volatile oil, kerosene, or
gasoline), (c) lubricant washing facilities.
(52) LEATHER MANUFACTURING
(a) washing facilities, (b) line soaking facilities, (c) tannin, soaking
facilities, (d) chrome bathing facilities, (e) dyeing facilities.
(53) CLASS MANUFACTURING
(a) grinding and washing facilities, (b) gas washing facilities.
(54) CEMENT MANUFACTURING
(a) centrifuger, (b) shaper, (c) wet conditioning facilities.
(55) READY MIXED CONCRETE MANUFACTURING
(a) batcher plant.
(56) ORGANIC SAND BOARD MANUFACTURING
(a) mixing facilities.
(57) SYNTHETIC BLACK LEAD ELECTRODE MANUFACTURING
(a) shaping facilities.
(58) RAW POTTERY MATERIALS MANUFACTURING
(a) water jet crusher, (b) separation facilities, (c) acid treatment facili-
ties, (d) dehydration facilities.
(59) MACADAM QUARRING
(a) water jet crusher, (b) separation facilities.
(60) SAND COLLECTION
(61) IRON INDUSTRY
(a) tar and gas separation facilities, (b) gas coiling and washing facilities,
(c) rolling facilities, (d) hardening facilities, (e) wet dust collector.
(62) NONFERREOUS METALS MANUFACTURING
(a) reduction basins, (b) electrolysis facilities, (c) hardening facilities,
(d) mercury refinery facilities, (e) waste gas washing facilities, (f) wet
dust collector.
(63) METRIC GOODS MANUFACTURING AND MACHINERY INDUSTRY
(a) hardening facilities, (b) surface treatment facilities electrolysis),
(c) cadmium electrode and lead electrode processing facilities, (d) mer-
cury refining facilities, (e) waste gas washing facilities.
13
-------
(64) TOWN GAS AND COKE MANUFACTURING
(a) coal tar and gas-liquid separation facilities, (b) cooling and washing
facilities including desulfurization facilities.
(64)-2 WATER CLEANING FACILITIES (excluding those whose cleaning capa-
bility is less than 10,000m3 a day) OF WATER SUPPLY FACILITIES
(defined by the provision of paragraph 7 of Article 3 of the Water Supply
Law), INDUSTRIAL WATER SUPPLY FACILITIES (defined by the
provision of paragraph 6 of Article 2 of the Industrial Water Supply Busi-
ness Law) or PRIVATE INDUSTRIAL WATER SUPPLY FACILITIES
(defined by the provision of paragraph 1 of Article 21 of the same Law)
(a) depositing facilities, (b) filter facilities.
(65) (a) acid and alkali treatment facilities of metal surface.
(66) (a) electro-plating facilities.
(66)-2 LODGING SERVICE (defined by the provision of paragraph 1 of Article 2
of the Lodging Service Law, excluding boarding house service)
(a) cooking facilities, (b) bath facilities, (c) washing facilities.
(67) LAUNDRY
(a) washing facilities.
(68) PHOTO DEVELOPING
(a) automatically washing facilities of film.
(69) (a) slaughterhouse.
(69)-2 CENTRAL WHOLESALE MARKET FACILITIES (concerning marine pro-
duction defined by the provision of paragraph 3 of Article of the Wholesale
Market Law)
(a) wholesale market, (b) intermediate wholesale market.
(70) (a) waste oil treatment facilities.
(71) (a) automatically washing facilities of car.
(71)-2 RESEARCH, DETERMINATION, MEASUREMENT OR PROFESSIONAL
EDUCATION FOR SCIENCE AND TECHNOLOGY (excluding human
science)
(a) washing facilities, (b) hardening facilities.
(72) (a) night soiLtreatment plan (more than 501 population served).
(73) (a) sewage treatment plant.
(74) (a) waste water treatment plant.
The water quality standards set to prevent the discharge of sewage into the
public sewerage system are designed to conform the water quality of the effluent to
the technical standards provided under Article 8 of the Law. They are divided into
two categories. One is to designate substances to be controlled for a nationwide
uniform application under Cabinet Order. The other group of standards is set by
regulations instituted by the general manager of the public sewerage system taking
into account the types and distribution of factories in a given area, the capacities of
the final treatment facilities in the area and other factors. As to the items which
could damage sewerage facilities, such as the temperatures, hydrogen ion concen-
trations, the content of normal hexan extracts and iodic consumption, the general
14
-------
manager of the public sewerage system, as in the past, will decide obligations for
installing pre-treatment facilities by regulations, and the direct penalty provisions
are not introduced from the standpoint of functional damage.
The standards established by Cabinet Order for a nationwide uniform appli-
cation (Table 4) provide for copper, zinc and other substances which are usually dif-
ficult to treat at the final sewage treatment facilities. These are picked from the list
of substances provided for under the Water Pollution Control Law as substances
dangerous to human health, such as cadmium and cyanide (health items) and those
that could adversely affect the living environment, such as copper and zinc (living
environment items). The control values are identical to the standards provided for
under the Water Pollution Control Law and regulations instituted thereunder.
Table 4 Uniform Standards Set by Cabinet Order
Substances
Cadmium and Its Compounds (Cd)
Cyanide Compounds (CN)
Organic Phosphorus Compounds
(Parathion, Methyl Parathion,
Methyl Demeton and EPN only)
Lead and Its Compounds 0?t>)
Chromium (VI) Compounds [Cr (VI) ]
Arsenic and Its Compounds (AS)
Total Mercury f-H§)
Alkyl Mercury Compounds
PCB
Phenols
Copper (Cu)
Zinc (Zn)
Dissolved Iron (Fe)
Dissolved Manganese (Mn)
Chrome (Cr)
Fluorine (F)
Permissible Limits
0.1 mg/fi
1 mg/2
1 mg/2
1 mg/e
0.5 mg/fi
0.5 mg/fi
0.005 mg/fi
Not detectable
0.003 mg/fi
5 mg/fi
3 mg/fi
5 mg/fi
10 mg/C
10 mg/fi
2 mg/fi
15 mg/fi
As to pH, BOD and other substances that can be disposable at the final treat-
ment facilities, the general manager of the public sewerage system, as in the past, can
decide, through the enactment of regulations, the water quality standards within the
limits provided for under Cabinet Order taking into consideration the treatment
capacity of each facility and other factors.
Under the Water Pollution Control Law, exceptions are provided for living
environment items, such as that factories or establishments whose average daily dis-
charge of the effluent is less than 50 m3 are exempted from direct penalty pro-
visions relevant to the sewage standards. With a view to coordinating relevant pro-
visions with the Water Pollution Control Law, the sewage exempted from appli-
cation of the Water Pollution Control Law are placed outside controls by the
Sewerage Law. But the controls are applied to those factories or establishments
whose average daily discharge is less than 50 m3 when they are also controlled
by regulations enforced under the Water Pollution Control Law.
15
-------
Table 5 Limit of Standards Allowed to be Set
by the Regulation
Substances
PH
BOD
ss
N-hexane Extracts
Mineral Oil
Animal and Vegetable Fats
Permissible Limits
5-9
600 mg/2
600 mg/£
5 mg/E
30 mg/C
With respect to sanitary sewage discharged from facili-
ties used for manufacturing and gas supplying business,
the standards can be tightened up to those at the table
below, if it is recognized that the total amount of sanitary
sewage from them is equivalent to more than one-fourth
of sanitary sewage to be treated at the treatment facility,
that it will not be sufficiently diluted by other sanitary
sewage before reaching the treatment facility or that there
is any other justifiable reason.
Substances
pH
BOD
SS
Permissible Limits
5.7-8.7
300 mg/2
300 mg/2
Those who have violated this direct penalty provision are liable to penal servi-
tude for less than six months or a fine of less than ¥200,000 (in accidental cases
imprisonment for less than three months or a fine of less than ¥100,000).
The aforementioned controls are applied only to the specified factories. But
when the sewage from non-specified factories is inferior, the general manager of the
public sewerage system, as in the past, can take necessary measures to them by
regulations, including an order for the installation of pre-treatment facilities.
2.2 INTRODUCTION OF A PRIOR CHECKING SYSTEM
Another major point of revision is the establishement of a prior checking
system in which the general manager of the public sewerage system can examine in
advance plans for the construction or renovation of specified facilities which could
discharge inferior sewage. The details are followng.
2.2.1 NOTIFICATION OF CONSTRUCTION OF SPECIFIED FACILITIES
Persons who use the public sewerage system to discharge sewage from their
factories or establishments must submit notifications to the general manager of the
public sewerage system, when they build specified facilities or take other measures
on them.
This provision enables the general manager of public sewerage system to fully
examine in advance the construction and renovation of specified facilities by
obliging the operators to submit their plans in advance to the general manager of the
public sewerage system and by ordering modifications. Matters subject to notifica-
tion are as follows:
a. Name or title and address, and name of the representative if factory or es-
tablishment is a corporate body
16
-------
b. Name of factory or establishment and its location
c. Sort of specified facilities
d. Structure of specified facilities
e. Method of use of specified facilities
f. Method of treating sewage discharged from specified facilities
g- Volume, water quality of sewage discharged to public sewerage system and
other matters specified by the Ordinance of the Ministry of Construction
2.2.2 ORDERS FOR MODIFICATION OF PLANS
When a notification for the construction of specified facilities is submitted the
general manager of the public sewerage system can order, only within 60 days from
the date of notification, the modification of the structure of the relevant specified
facilities and of the sewage treatment method, if the water quality of sewage to be
discharged to the public sewerage system is not deemed to conform to the discharge
standards. During this period, construction work and other procedures concerning
the specified facilities are to be prohibited to be done. In ordering the modification
of the plan, the general manager can order the abrogation of the plan, if he considers
it impossible to prevent the inflow to the sewerage system of the sewage unable to
meet the control standards through the modification of the plan.
However, even within 60 days from the date of notification, the general
manager of the public sewerage system can approve of the construction and other
measures for the specified facilities if he considers the content of the notified plan
appropriate.
2.3 INTRODUCTION OF IMPROVEMENT ORDER SYSTEM
Along with the prior checking system allowing orders to be given to modify
the notified plan for the construction of specified facilities, the general manager of
the public sewerage system can order the operator of specified facilities to improve
their structure, their method of sewage treatment, etc. in order to check in advance
the inflow of inferior sewage to the sewerage system, when he considers that the
relevant facilities could discharge sewage that fails to meet the control standards.
The improvement order includes the improvement of the structure of specified
facilities and the suspension of the use of specified facilities and of the discharge of
sewage for a certain period. The revision of the Sewerage Law as mentioned above
will go into force as of May 1, 1977. But the sewage discharged from the existing
specified factories will be exempted from the direct penalty and improvement order
provisions for six months from the date of enforcement of the revised law (the
period of exemption is one year for facilities designated under Cabinet Order).
3. PRESENT STATE OF CONTROLS ON FACTORY EFFLUENT
3.1 PRESENT STATE
3.1.1 NUMBER OF SPECIFIED FACTORIES
Through the introduction of a prior checking system under the revised
Sewerage Law, persons who plan to construct specified facilities will be obliged to
notify the general manager of the public sewerage system of thier content and other
matters. But even the existing law requires a notification to the general manager of
17
-------
the public sewerage system from those who will establish specified facilities or dis-
charge sewage in quantities as specified (more than 50 m3 per day) or of water
quality as specified (Table 2) under Cabinet Order.
The numbers of specified factories (factories and other establishments equip-
ped with specified facilities) within specific sewered areas as of March 31, 1976 are
as listed on Table 6.
And the numbers of those who submited prior notification except those who
established specified facilities are as listed on Table 7.
Table 6 Numbers of Specified Factories
Classification
Plants Generated Related
Pollution Materials Relat-
ed Health Hazard
Plants Generated Pollu-
tion Material Related to
Living Environment, Dis-
charging more than 50
m3 /day of Waste Water
Plants Generated Pollu-
tion Material Related to
Living Environment, Dis-
charging less than 50
m3 /day of Waste Water
Miscellaneous
Municipalities
Major Cities*) (10)
Ordinary Cities
Sub-total
Major Cities (10)
Ordinary Cities
Sub-total
Major Cities (10)
Ordinary Cities
Sub-total
Total for
Major Cities
Total for
Ordinary Cities
Total
Number of
Specified
Factories
4.813
1,668
6,481
1,298
1,497
2,795
22,480
18,594
41,074
28,591
21,759
50,350
Number of
Required
Pretreatment
Facilities (A)
4,469
1,143
5,612
717
877
1,594
926
3,448
4,374
6,112
5,468
11,580
Number of
Installed
Pretreatment
Facilities (B)
3,672
921
4,593
419
608
1,027
450
1,535
1,985
4,541
3,064
7,605
(B)/(A)%
82.2
80.6
81.8
58.4
69.3
64.4
48.6
44.5
45.4
74.3
56.0
65.7
*) Major Cities: Tokyo, Osaka, Sapporo, Yokohama, Kawasaki, Nagoya, Kyoto, Kobe, Kitakyushu, Fukuoka.
Table 7 Non-Specified Factories
Classification
Plants Generated Related Pollution
Materials Related Health Hazard
Plants Generated Pollution Material Re-
lated to Living Environment, Discharging
less than 50 m3/day of Waste Water
Plants Generated Pollution Material
Related to Living Environment, Dis-
charging less than 5 Om3 /day of Waste-
Water'
Miscellaneous
Municipalities
Major Cities*) (10)
Ordinary Cities
Sub-total
Major Cities (10)
Ordinary Cities
Sub-total
Major Cities (10)
Ordinary Cities
Sub-total
Total for
Major Cities
Total for
Ordinary Cities
Total
Number of
Required
Pretreatment
Facilities (A)
57
73
130
157
195
352
381
1,307
1,688
595
1,575
2,170
Number of
Installed
Pretreatment
Facilities (B)
35
46
81
116
115
231
289
459
748
440
620
1,060
(B)/(A)%
61.4
63.0
62.3
73.9
59.0
65.6
75.9
35.1
44.3
73.9
39.4
48.8
*) Major Cities: Tokyo, Osaka, Sapporo, Yokohama, Kawasaki, Nagoya, Kyoto, Kobe, Kitakyushu, Fukuoka.
18
-------
On Table 8 are the numbers of specified factories that come under the Water
Pollution Control Law. Under the Law the uniform sewer standards on BOD and
other living environment-related items are applied to those specified factories whose
average daily discharge exceeds 50 m3 and health-related items are applied to all
specified factories. The number of specified factories subject to the uniform sewer
standards is 31,891 or 14% of the total. The corresponding number and percentage
for those factories within specific sewer areas are 9,276 and 18%. The ratios of
those discharging more than 50 m3 daily are about the same. And, water used by
manufacturers during 1974 totaled 18.1 billion m3, and the total excluding the
amount used for raw material was 16.9 billion m3. On the other hand, the amount
of factory effluent flown into the final treatment facilities was 0.8 billion m3 or
18% of the total.
3.1.2 TYPES OF SPECIFIED FACTORIES
Table 10 shows the types of specified factories. Many of the specified facto-
ries are small in scale.
Table 8 Specified Facilities Designated Under the Water Pollution Control Law (in Fiscal 1974)
the Table
1 in
Cabinet
Order
1
1-2
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Kind of Business or
Na-ne of Facilities
Mining and
Pig House, Horse House, Cow
House Concerning Livestock
Farming
Meat Packing and Poultry
Processing
Sea Foods Manufacturing
Canned and Frozen
Vegetables and Fruits
Manufacturing
Miso, Soy-Sauce, Edible
Aminoacid, Glutamic Acid
Vegetable Sauces and Vinegar
Manufacturing
Wheat Flour Manufacturing
Sugar Manufacturing
Bakery and Confectionary
Rice Cake and Malt Manufac-
turing
Soft Drink Manufacturing and
Brewery
Feed Staff and Organic
Fertilizering Manufacturing
Oil and Fat Manufacturing
Yeast Manufacturing
Starch Manufactuing
Dextrose Manufacturing
Noodles Manufacturing
Number of Specified Factories
Total
©
103
33,718
2,697
9,640
2,367
3,527
45
99
1,582
696
4,728
485
334
9
309
67
4,390
Whose
Volume of
Effluents
Per Day is
More Than
50m3
62
498
816
976
479
176
13
81
97
67
556
163
107
7
234
41
91
Less
Than
50m3 /d
©
41
33,220
1,881
8,664
1,888
3,351
32
18
1,485
629
4,172
322
227
2
75
26
4,299
Sum of (2)
Which
Discharge
Waste Con-
taining Toxic
Substances
©
3
0
1
0
0
3
Number of
Factories to be
Controlled by
the Uniform
Effluent
Standard
© + ®
65
498
817
976
479
176
13
81
97
67
559
163
107
7
234
41
91
0/s©
0.2
1.7
2.7
3.1
1.5
0.7
0.0
0.3
0.3
0.2
1,8
0.5
0.3
0.0
0.7
0.1
0.3
19
-------
Table 8 Classification of Specified Factories (in Fiscal 1974) 2/3
No. of
the fable
lin
Cabinet
Order
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
36
37
38
39
40
41
42
43
44
45
Kind of Business or
Name of Facilities
Bean Foods Manufacturing
Instant Coffee Manufacturing
Textile Industry
Wool Scouring and Washing
Synthetic Textile Manufac-
turing
Chemical Finishing of Woods
Pulp and Paper Manufacturing
Fertilizer Manufacturing
Sodium Hydroxide and Potas-
sium Hydroxide Manufac-
turing
Inorganic Pigment Manufac-
turing Inorganic Chemicals
Manufacturing Excluding
Items of 25 and 26
Ethylene Derivates Manufac-
turing (Carbide Process)
Coal Tar Products Manufac-
turing
Fermentation Industry Ex-
cluding Items of 5, 10
Methane Derivates Manufac-
turing
Synthetic Plastic Manufac-
turing
Synthetic Plastic Manufac-
turing
Synthetic Rubber Manufac-
turing
Organic Gum Chemicals
•Manufacturing
Synthetic Detergent Manu-
facturing
Petrochemical Industries
(Carbohydrate and Its
Derivates)
Soap Manufacturing
Hydrogenated Oil Manufac-
turing
Fatty Acids Manufacturing
Perfumery Manufacturing
Gelatine and Glue Manufac-
turing
Photo Sensitive Goods
Manufacturing
Natural Resin Manufacturing
Woods Chemical Manufac-
turing
Number of Specified Factories
Total
©
21,841
9
4,934
63
52
162
1,258
73
23
69
405
69
5
39
18
67
271
23
9
24
123
26
7
10
28
17
22
7
Whose
Volume of
Effluents
Per Day is
More Than
50m3
©
131
5
1,615
36
49
10
818
56
23
44
259
35
2
22
12
38
196
15
9
19
103
7
4
6
17
8
9
3
Less
Than
50m3/d
©
21,710
4
3,319
27
3
152
440
17
25
146
34
3
17
6
29
75
8
5
20
19
3
4
11
9
13
4
Sum of (?)
Which
Discharge
Waste Con-
aining Toxic
Substances
(D
108
4
46
1
3
19
3
1
3
5
Number of
Factories to be
Controlled by
the Uniform
Effluent
Standard
©+j3)
=(4)
131
5
1,723
40
49
56
818
57
23
47
278
38
2
22
12
39
199
15
9
19
103
7
4
6
17
8
14
3
(%)
®/S©
0.4
0.0
5.4
0.1
0.2
0.2
2.7
0.2
0.1
0.1
0.9
0.1
0.0
0.1
0.0
0.1
0.6
0.0
0.0
0.0
0.3
0.0
0.8
0.0
0.1
0.0
0.0
0.0
20
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Table 8 Classification of Specified Factories (in Fiscal 1974) 3/3
No. of
the Table
lin
Cabinet
Order
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
Kind of Business or
Name of Facilities
Organic Chemical Manufac-
turing Excluding Items From
28 to 45
Pharmaceutical Manufacturing
Gunpowder Manufacturing
Pesticides Manufacturing
Reagent Manufacturing
Oil Refining Industry
Leather Manufacturing
Glass Manufacturing
Cement Manufacturing
Ready Mixed Concrete
Manufacturing
Organic Snad Board Manufac-
turing
Synthetic Black Lead Elec-
trode
Raw Pottery Materials
Manufacturing
Macadam Quarring
Sand Collection
Iron Industry
Nonferreous Metals
Metaric Goods Manufacturing
and Machinery Industry
Town Gas and Coke
Manufacturing
Acid and Alkali Treatment
Facilities of Metal Surface
(a) Electro-Plating Facilities
(b) Hotel and Inn
Laundry
(a) Washing Facilities
Photo Developing
(a) Slaughter House
Waste Oil Treatment Facilities
(a) Automatically Washing
Facilities of Car
(b) Natural Science Institute
and Laboratory
Night Soil Treatment Plant
(More Than 501 Population
Served.)
Sewage Treatment Plant
Waste Water Treatment Plant
Total
Number of Specified Factories
Total
©
246
221
12
52
6
81
462
698
2,889
2,999
24
18
1,295
732
2,284
695
236
1,385
162
4,594
3,289
61,948
25,826
759
512
35
11,071
3,744
6,607
413
185
227,929
Whose
Volume of
Effluents
Per Day is
More Than
50m3
159
139
8
11
2
63
161
107
163
277
4
17
253
336
1,211
307
122
570
137
1,609
1,177
3,473
241
238
278
7
248
744
5,482
410
144
26,112
©
87
82
4
41
4
18
301
591
2,726
2,722
20
1
1,042
396
1,073
388
114
815
25
2,985
2,112
58,475
25,585
521
234
28
10,823
3,000
1,125
3
41
201,817
Sum of©
Which
Discharge
Waste Con-
taining Toxic
Substances
@
6
5
10
1
10
357
150
130
28
7
15
232
4
481
1,882
1
1
267
1
1,980
2
9
5,779
Number of
Specified
Factories to be
Controlled by
the Uniform
Effluent
Standard
©+©
165
144
8
21
3
63
171
464
313
407
4
17
281
336
1,211
314
137
802
141
2,090
3,059
3,474
242
550
279
7
248
2,724
5,484
410
153
31,891
(%)
@/2©
0.5
0.5
0,0
0.1
0.0
0.2
0,5
1.5
1.0
1.3
0.0
0.1
0.9
1.1
3.8
1.0
0.4
2.5
0.4
6.6
9.6
10.9
0.8
1.6
0.9
0.0
0.8
8.5
17.2
1.3
0.5
100.0
21
-------
Table 9 Volumes of Factory Effluent by Scale
(Unit: 1,000m' /day)
Number
of
Employee
Total
1-29
30-49
50-99
100-199
200-299
300-499
500-999
1,000 and over
Number
of
Establishment
417,876
361,075
23,270
18,330
8,464
2,643
1,905
1,385
804
Sum of
Industrial
Shipment
(billion yen)
125,702
20,755
8,245
12,620
13,378
8,737
11,466
17,070
33,431
Amount
of
Water Used
®
49,606
7,357
2,299
3,382
4,275
3,293
5,052
9,680
14,268
Water Used by Objective
For Boilers
2,819
434
183
245
228
217
250
523
739
For Mate-
612
136
106
102
98
42
62
56
10
Amount
of
Sewage
46,175
6,787
2,010
3,035
3,949
3,034
4,740
9,101
13,519
Note: Amount of Industrial Waste Water from the establishments of 1 to 29 employee is estimated.
3.1.3 INSTALLATION STATE OF PRE-TREATMENT FACILITIES
The Sewerage Law before revision provided that the general manager of the
public sewerage system, through the enactment of regulations, establish standards
for the installation of pre-treatment facilities in accordance with the standards set by
Cabinet Order. Therefore, the standards applied for the construction of pre-
treatment facilities vary with cities, towns and villages. The number of establish-
ments that are required to install pre-treatment facilities is 13,750. The number of
those already equipped with such facilities is 8,665 or 63% of the total. The ratio of
the factories which have already had pre-treatment facilities is higher among those
having the facilities such as electroplating discharging harmful substance.
3.1.4 SURVEILLANCE ON FACTORY EFFLUENT
The general managers of the public sewerage system can order his staff to enter
land or buildings owned by others and inspect sewage systems, pre-treatment facili-
ties and other objects for the purpose of maintaining the structure and functions of
the public sewerage system and conforming the water quality of the effluent to the
technical standards provided for under Article 8 of the Law. The number of in-
spections conducted in fiscal 1975 totaled approximately 27,000.
For proper management of the public sewerage system, its general manager can
also collect from the operator of the specified facilities reports on the state of
factories discharging sewage and pre-treatment facilities as well as on the water
quality of the sewage discharged by these facilities. The number of reports collected
during fiscal 1975 totaled about 6,700.
The administrative actions taken by the general manager of the public sewerage
system during fiscal 1975 under the Sewerage Law are as follow:
Order for Improvement: 67 cases
Recommendation for Improvement: 271 cases
Warning: 46 cases
Total: 384 cases
The figure represents an increase of 328 cases over fiscal 1974. This is a result of
strengthened surveillance by the general manager of the public sewerage system just
22
-------
Table 10 Types of Specif led Factories
No. of the
Table 1 in
Cabinet
Order
1
1-2
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
Kind of Business or
Name of Facilities
Mining and Coal Washing
Pig House, Horse House, Cow House
Concerning Livestock Farming
Meat Packing and Poultry Processing
Sea Foods Manufacturing
Canned and Frozen Vegetables and
Fruits Manufacturing
Miso, Soy-Sauce, Edible Aminoacid,
Glutamic Acid Vegetable Sauces and
Vinegar Manufacturing
Wheat Flour Manufacturing
Sugar Manufacturing
Bakery and Confectionary
Rice Cake and Malt Manufacturing
Soft Drink Manufacturing and Brewery
Feed Staff and Organic Fertilizering
Manufacturing
Oil and Fat Manufacturing
Yeast Manufacturing
Starch Manufacturing
Dextrose Manufacturing
Noodles Manufacturing
Bean Foods Manufacturing
Instant Coffee Manufacturing
Textile Industry
Wool Scouring and Washing
Synthetic Textile Manufacturing
Chemical Finishing of Woods
Pulp and Paper Manufacturing
Fertilizer Manufacturing
Sodium Hydroxide and Potassium
Hydroxide Manufacturing
Inorganic Pigment Manufacturing
Inorganic Chemicals
Manufacturing Excluding Items of 25
and 26
Ethylene Derivates Manufacturing
(Carbide Process)
Coal Tar Products Manufacturing
Fermentation Industry Excluding Items
of 5, 10
Methane Derivates Manufacturing
Synthetic Plastic Manufacturing
Synthetic Plastic Manufacturing
Synthetic Rubber Manufacturing
Organic Gum Chemicals Manufacturing
Synthetic Detergent Manufacturing
Petrochemical Industries (Carbohydrate
and Its Derivates)
Soap Manufacturing
Number of
Specified
Factories
3
36
278
822
587
319
67
35
1,016
246
506
30
57
3
26
13
1,196
3,425
2
5,070
78
1
6
55
3
2
25
83
6
2
9
6
113
37
9
4
28
12
34
Number of
Required
Pretreat-
ment Faci-
lities (A)
3
9
106
233
99
98
30
8
276
45
187
23
45
1
10
10
120
292
1
558
62
1
2
42
2
2
23
75
3
2
5
3
42
28
5
3
13
9
19
Number of
Installed
Pretreat-
ment Faci-
lities (B)
2
5
53
113
44
35
7
4
76
17
105
12
19
1
6
9
29
78
1
191
12
1
0
32
1
2
19
67
3
2
4
3
37
16
5
3
8
7
17
(B)/(A) %
67
56
50
48
44
36
23
50
28
36
56
52
42
100
60
90
24
27
100
34
19
100
0
76
50
100
83
89
100
100
80
100
88
57
100
100
62
78
89
23
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Table 10 (Continued)
*Jo. of the
Table 1 in
Cabinet
Order
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
Kind of Business or
Name of Facilities
Hydrogenated Oil Manufacturing
Fatty Acids Manufacturing
Perfumery Manufacturing
Gelatine and Glue Manufacturing
Photo Sensitive Goods Manufacturing
Natural Resin Manufacturing
Woods Chemical Manufacturing
Organic Chemical Manufacturing Exclud-
ing Items From 28 to 45
Pharmaceutical Manufacturing
Gunpowder Manufacturing
Pesticides Manufacturing
Reagent Manufacturing
Oil Refining Industry
Leather Manufacturing
Glass Manufacturing
Cement Manufacturing
Ready Mixed Concrete Manufacturing
Organic Snad Board Manufacturing
Synthetic Black Lead Electrode
Raw Pottery Materials Manufacturing
Macadam Quarring
Sand Collection
Iron Industry
Nonferreous Metals
Metaric Goods Manufacturing and
Machinery Industry
Town Gas and Coke Manufacturing
Acid and Alkali Treatment Facilities of
Metal Surface
(a) Electro-Plating Facilities
(b) Hotel and Inn
Laundry
(a) Washing Facilities
Photo Developing
(a) Slaughter House
Waste Oil Treatment Facilities
(a) Automatically Washing Facilities of
Car
(b) Natural Science Institute and Labor
Laboratory
Night Soil Treatment Plant (More Than
501 Population Served.)
Sewage Treatment Plant
Waste Water Treatment Plant
Number of
Specified
Factories
4
9
10
3
29
2
4
105
88
4
6
5
24
211
71
67
88
4
5
14
8
7
267
76
822
24
2,409
2,327
11,623
8,273
1,162
31
94
2,650
565
55
-
15
Number of
Required
Pretreat-
ment Faci-
lities
4
8
8
3
25
2
1
83
62
3
5
5
19
197
51
33
49
3
2
12
2
3
113
65
283
19
2,092
2,295
634
666
834
30
77
1,304
232
20
-
12
lumber of
Installed
Pretreat-
ment Faci-
lities
4
7
7
1
20
2
1
73
51
1
5
5
19
18
38
23
41
3
2
10
1
2
89
54
197
15
2,006
1,964
269
119
559
21
70
1,031
116
19
-
7
(B)/(A) %
100
88
88
33
80
100
100
88
82
33
100
100
100
9
75
70
84
100
100
83
50
67
79
83
70
79
96
86
42
18
67
70
91
79
50
95
58
24
-------
as in the case of the inspection of water quality under the Sewerage Law which
sharply increased from about 12,000 cases in fiscal 1974 to about 17,000 cases in
fiscal 1975.
Thus, guidance and surveillance on pre-treatment facilities in cities, towns and
villages are being strengthened in recent years with particular emphasis on those in
cities. The number of officials engaged in these works in city, town and village
offices totaled 733 during fiscal 1976.
Table 11 Surveillance on Pre-treatment Facilities (1975)
Classification
Reporting Commencement of
Utilization (Accumulation)
Inspection of Private Sewer
Collection of Reports
Order for Improvement
Municipalities
Major Cities (10)
Others
Total
Major Cities (10)
Others
Total
Major Cities (10)
Others
Total
Major Cities (10)
Others
Total
Number
12,107
13,532
25,639
14,077
12,902
26,979
2,855
3,889
6,744
135
249
384
Major Cities: Tokyo, Osaka, Sapporo, Yokohama, Kawasaki,
Nagoya, Kyoto, Kobe, Kitakyushu, Fukuoka.
3.2 AID SYSTEM FOR CONSTRUCTION OF PRE-TREATMENT FACILITIES
Under the Sewerage Law before revision, factories and other establishments
were already obliged to equip themselves with pre-treatment facilities. As a result of
the introduction of the prior checking system and the direct penalty system under
the revised law, the construction of the pre-treatment facilities has become indis-
pensable. The standards for the construction of the pre-treatment facilities are not
uniform, since they are decided by regulations instituted respectively by cities,
towns and villages. The factories which have not installed the pre-treatment facili-
ties total 5,085 in number and represent 37% of those which are required such
facilities. Among reasons for delayed action are lack of funds, lack of land, under
planning and under construction as listed on Table 12. Many of the factories which
have not yet built the pre-treatment facilities are small businesses, and therefore the
state and local governments have established aid systems to promote the construc-
tion of the facilities as listed on Table 13.
3.3 PUBLICATION OF GUIDANCE MANUAL
Under the revised Sewerage Law, cities, towns and villages serving as general
manager of the public sewerage system are obliged to assume clerical works con-
cerning the prior checking system and other procedures. This means that cities,
towns and villages will handle the same clerical works as those assumed by the
prefectural governments (partly delegated to major cities) provided for under the
25
-------
Water Pollution Control Law, including the prior checking system. In order to
help smaller administrative bodies carry out the newly-assigned work smoothly,
the state has decided to publish a guiding manual for the prior checking system
and other procedures, and the Sewerage Association is now studying the plan.
The state has also instruct the local governments to prepare new registers
for the pre-treatment facilities in a unified form with a view to strengthening surveil-
lance on specified establishments and giving proper guidance.
Table 12 Reasons for Non-Installing
Pre-treatment Facilities
Lack of Money
Lack of Space
Planning to Install
Tentative Treat-
ment
Planning to Move
Others
Total
Specified
Factories
(%)
34.3
17.8
15.0
11.1
0.8
21.0
100.0
Non-specified
Factories
(%)
24.3
0.9
5.7
26.3
0.1
42.7
100.0
Table 13.1 Aid System of Financial Institution for Installing
Pre-treatment Facilities (March 1976)
Corporation
Environmental Pollution
Control Service Cor-
poration
-
Japan Development
Bank
/A recommendation of\
f the authority con-
A cerned is necessary to ,
Smaller Business
Finance Corporation
People's Finance
Corporation
Smaller Business Pro-
motion Corporation
Object Enterprise
Big Enterprise
Small-to-Middle Enter-
prise
/Capital Stock; less than\
[ 100 million yen ]
\ Employee; less than J
\> 300
Enterprises Except Object
Enterprises of the Loan of
the Smaller Business
Finance Corporation
Small-to-Middle Enter-
prise
/Capital Stock; less thanv
/ 100 million yen \
\ Employee; less than /
\ 300 '
Mainly Smaller-to-Middle
Enterprise
.Capital Stock; less than.
/ 10 million yen \
\ Employee; less than /
\ 100 '
Cooperative Anti-Pollu-
tion Business of Business
Cooperative Association
etc.
Maximum
Sum of
Loan
Non-limit
Non-limit
Direct
Loan:
150
million yen
Loan by
Agent
40 mil-
lion yen
18 mil-
lion yen
Non-limit
Interest Rate
(per year)
Big Enterprise
Cooperative Anti-Pollu-
tion Facilities
First 3 years; 7.5%
' Later; 7.7%
Individual Anti-Pollu-
tion Facilities; 7.7%
Smalt-to-Middle Enter-
prise
Cooperative Anti-Pollu-
tion Facilities
First 3 years; 4.5%
Later; 5.0%
Individual Anti-Pollu-
tion Facilities; 6.0%
First 3 years; 7.7%
Later; 8.2%
First 3 years; 7.0%
Later; 7.2%
First 3 years; 7%
Later; 7.2%
Non-interest
Term of Redemption
Cooperative Anti-Pollu-
tion Facilities
{Instrument and Equip-
ment; 10 years
(unredeemed 1 year)
Others; 20 years
(unredeemed 3 years)
Individual Anti-Pollution
Facilities; 10 years
(unredeemed 1 year)
About 10 years
10 years
(unredeemed 2 years)
10 years
(unredeemed 2 years)
15 years
(unredeemed 2 years)
Amount of Loan
(1976F.Y.)
Cooperative Anti-Pollu-
tion Facilities, Indi-
vidual Anti-Pollution
Facilities. Others;
127 billion yen
Pollution Prevention
Facilities, Anti-Pollu-
tion Facilities, Others;
128 billion yen
Safety Loan, Anti-Pollu-
tion Loan; 53 billion
yen
Safety Loan, Anti-Pollu-
tion Loan; 10 billion
yen
2 billion yen
26
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Table 13.2 Aid System of Major 7 Cities for Installing Pre-treatment Facilities
City
Tokyo Metropolis
/All 23 ward have the v
/ system to supply \
\ money for interest J
Bother than these. '
Yokohama
Nagoya
Kyoto
Osaka
Kobe
Kitakyushu City
Name of System
Tokyo Metropolis Media-
tion System for Loaning
of Anti-Pollution I und
Tokyo Metropolis Loan-
ing System for Anti-
Pollution Fund
Yokohama Cily Loaning
System for Small-lo-
Middle Enterprise
(Anti-Pollution fund)
Nagoya Cily Mediation
System for Loaning of
Anti-Pollution Facilities
Improvement Fund
Kyoto City Anti-Pollu-
tion Fund System
Osaka City Loaning
System for Anti-Pollu-
tion Facilities
Kobe City General Loan-
ing System of Anti-
Pollution Fund
Kitakyushu City Loaning
System of Anti-Pollu-
tion Fund
Maximum
Sum of Loan
20 million yen
7 million yen
25 million yen
25 million yen
20 million yen
20 million yen
20 million yen
10 million yen
Interest Rate
Metropolis Supplies
Money for Interest so that
Interest Rate may be 2
percentage.
29f
Cily Supplies All Money
for Interest.
6.8ft
\.S7r
City Supplies Money for
Interest so that Interest
Rate may be 2 percentage
(1 percentage for small
enterprises)
Cily Supplies Money for
Interest so that Interest
Rate may be 2.76 per-
centage.
City Supplies All Money
for Interest.
Term of Redemption
7 years
(unredeemed 6 months)
7 years
(unredeemed 6 months)
3 to 9 years
7 years
(unredeemed 1 year)
12 years
7 years
7 years
7 years
Amount of Loan
(1976F.Y.)
5 billion yen
{including fund for
movement)
300 million yen
600 million yen
2 billion yen
660 million yen
(including fund for
movement)
150 million yen
650 million yen
300 million yen
Table 13.3 Utilization State of Aid System for
Installing Pre-treatment Facilities
(1971-1975 F.Y.)
Classification
National
Government
Local
Government
System
Environmental Pollution
Control Service Corpora-
tion
People's Finance
Corporation
Smaller Business Finance
Corporation
Smaller Business
Facility Modernization
Fund
Environmental Sanitation
Business Finance
Corporation
Sub-total
Prefecture
Municipality
Sub-total
Total
Number
45
327
56
14
1
443
117
834
951
1,391
Mentioned above are a summary of the revision of the Sewerage Law, the
state of controls on factory effluent before the revision and the new system of
surveillance under the revised law. A report on the state of the execution of the
revised law will be made on the next occasion.
27
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RECENT TOPICS IN WATER POLLUTION CONTROL
IN JAPAN
1. Current Progress on Water Pollution Control in Japan 29
2. Surveys for Total Emission Control for Organic Pollutants 32
3. Counter Measures for Eutrophication 33
4. Other Water Pollution Phenomena 34
4.1 Effluent Discharged in Warm Temperature 34
4.2 Long Time Duration of Turbid Water Flow from Dams 34
5. Environment Impact Assessment 35
28
-------
RECENT TOPICS IN WATER POLLUTION CONTROL
IN JAPAN
1. CURRENT PROGRESS ON WATER POLLUTION CONTROL IN JAPAN
The state of this country's water pollution caused by cadmium and other toxic
substances has improved lately with the years. In terms of BOD (or COD in the case
of lakes and sea water), the principal index of water quality with regard to organic
substances, water pollution in major water bodies has definitely slowed — even
improved in certain areas — since 1969, thanks to the rigorous regulation of efflu-
ents throughout the country in recent years. However, there still remain areas where
water pollution is not in good condition, and they include the river waters that run
through cities where the population and industries are heavily concentrated and the
coastal waters, particularly those of bays and inland seas where the waters are
trapped within a certain area. In the following pages, we will raise some questions to
be discussed at the 5th US/JAPAN conference on sewage treatment technology.
29
-------
Table 1 Degree of Nonconformity with Toxic Substance
Environmental Standards
Substance
Cadmium
Cyanides
Organic
Phosphorus
Lead
Hexavalent
Chrome
Fiscal Year
1970
71
72
73
74
75
70
71
72
73
74
75
70
71
72
73
74
75
70
71
72
73
74
75
70
71
72
73
74
75
Percentage
2.8 %
0.7
0.34
0.32
0.37
0.31
1.5
1.2
0.5
0.2
0.06
0.02
0.2
0.2
0
0
0
0
2.7
1.4
0.7
0.65
0.37
0.32
0.8
0.1
0.07
0.08
0.03
0.02
Substance
Arsenic
Total Mercury
Alkyl Mercury
Total
Fiscal Year
1970
71
72
73
74
75
70
71
72
73
74
75
70
71
72
73
74
75
70
71
72
73
74
75
Percentage
1.0 %
0.4
0.29
0.31
0.27
0.24
1.0
0.3
0.04
0.01
] See Notes*
0
0
0
0
.0
0
1.4
0.6
0.3
0.23
°-20U*
0.17J
T * i »i c- i >~!A j >T<-
Total Mercury Fiscal 74 and 75
Except Total Mercury
Numbers of Stations Exceeding Standards „„
- - — — — - - — — - - = 0%
Total Number of Stations
30
-------
Table 2 Degree of Nonconformity with Standards Relating
to the Living Environment
(FY'75,( ) shows FY'74)
Body of Water Category
Rivers
Lakes and Marshes
Sea Areas
AA
A
B
C
D
E
Total
AA
A
B
C
Total
A
B
C
Total
Numbers of Samples
Not Meeting Standards ea^
Total Numbers of Samples ^'"'
22.2
22.6
21.3
17.4
12.5
24.1
21.3
32.5
39.1
46.2
30.3
38.4
18.1
14.2
8.4
16.1
(24.2)
(23.0)
(23.3)
(18.7)
(13.4)
(27.1)
(22.4)
(33.4)
(34.7)
(48.1)
(25.3)
(35.1)
(18.8)
(14.0)
( 7.1)
(16.0)
31
-------
2. SURVEYS FOR TOTAL EMISSION CONTROL FOR ORGANIC
POLLUTANTS
The regulation introduced under the Water Pollution Control Law has only
taken into account the concentration of pollutants, but it seems insufficient that to
meet the demand for some specific water areas such as lakes and bays.
Therefore, surveys for introduction of so-called "total emission control," i.e.,
limitation of the emission of certain pollutants at each individual source so that the
total emission volume for a given water area is less than a level to meet the environ-
mental standards of the water area concerned.
The item for total emission control in water pollution control is intended to be
COD, one of the items relating to living environment, while the items for total
emission control in air pollution control are the items relating to human health.
In May 1975, Water Quality Bureau established a study committee for total
emission control (headed by Professor Ishibashi of Tokyo University). Since then,
the committee has studied fundamental structures of total emission control, i.e.,
pollutants or items to be controlled, water areas to be controlled (that means to be
designated), the method of calculation of total emission volume, allocation method
of total emission volume for each individual source, and the method of supervision
and measurement. The committee, after five times sessions, on September 1975,
issued an interim report consists of three parts (I. Fundamental plan, II. Way of
regulation, III. Supervision and measurement).
According to this, a fundamental survey is now carrying on as to Tokyo Bay,
Ise Bay and Seto Inland Sea for the introduction of total emission control of pollu-
tants, FY 1976. Also, in FY 1977, similar survey is intended as to Lake Biwa, Lake
Suwa and Lake Kasumi.
32
-------
3. COUNTER MEASURES FOR EUTROPHICATION
Among the recent features of water pollution, eutrophication problems in the
specific water areas, such as Seto Inland Sea, Tokyo Bay and Lake Kasumi, are most
troublesome.
As to "red tides" in the Seto Inland Sea, although the incidence of formation
has been increasing annually, the percentage of cases where damage has been suffer-
ed has been decreasing (Table 3). Part of the increased occurrence is actually due to
more comprehensive surveillance and reporting and not to more frequent red tide
formation, but even taking this factor into account, the virtually irreversible process
of eutrophication is still clearly being accelerated in those areas where nutrient salts
using microorganisms as their medium are building up in the water. The result is the
abnormal phenomenon of red tide formation and other types of secondary organic
pollution.
Table 3 Change in the Incidence of Red Tides
^"^--^^^^ Year
Item "~~" — ~^^
No. of Time (A)
No. of Times with Fish-
ery Damage (B)
(B) nn ,~,
(A) x 100 (96)
1967
48
8
17
1968
61
12
20
1969
67
18
27
1970
79
35
44
1971
136
39
29
1972
164
23
14
1973
210
18
9
1974
298
17
6
Source: Fishery Agency
Hence, from FY 1972, surveys of phosphorus and nitrogen are carried out
about major sea areas and lakes. From FY 1975, in Seto Inland Sea and Ise Bay,
and in FY 1977, adding Tokyo Bay, surveys for phosphorus and nitrogen are carried
out, as to input charge of each individual source, dissolving from bottom sediment,
plankton and so on.
As to synthetic detergent, JIS (Japan Industrial Standard) relating to synthetic
-------
detergent for clothes is amended in December 1976, and phosphate content is
reduced from 8 to 20% to less than 12%.
4. OTHER WATER POLLUTION PHENOMENA
4.1 EFFLUENT DISCHARGED IN WARM TEMPERATURE
Recently, power stations are becoming much larger and also they are apt to be
constructed in the areas where there have been no water pollution problems before.
So it is worried about that the effluent discharged from those power stations in state
of warm temperature affect badly to marine life and fishery.
In December 1975, "Thermal Pollution Committee" of Water Quality Commit-
tee of The Central Council for Control of Environmental Pollution issued an interim
report as to thermal pollution. It says that, the necessity of continuing surveys, and
sufficient environmental impact assessment when a new power station is planned,
and also the necessity of monitoring of environment after the completion of con-
struction.
4.2 LONG TIME DURATION OF TURBID WATER FLOW FROM DAMS
One of the problems recently raised is the long time duration of turbid water
flow down from dams after rainfall. Generally speaking, Japanese rivers are usually
clear in turbid because of geological and geographical conditions, and when it rains
the turbidity of river flow will go up promptly and when it clear up the turbidity of
river flow go down again promptly. But, if a dam is constructed it is usual there
comes a long time duration of comparably high turbid water after rain is up. And
this gives a bad effect to utilization of river water and fishery. And also is the
problem that a dam brings a cold water according to the way of discharge.
34
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5. ENVIRONMENT IMPACT ASSESSMENT
When various development works in relation to any public water areas are
carried out, it is necessary to take proper preventive measures so that such works
may not adversely affect the environment. For this purpose, it is very important to
make environmental impact assessment, thereby to make a careful check of the
possible effects such development works may have on the adjacent environment.
The above-mentioned basic policy was approved at the Cabinet meeting held in
June 1972 and was adopted as a government policy. Thereafter, the environmental
impact assessment has been carried on in accordance with this policy. This concept
of environmental impact assessment was embodied in various laws enacted at 71st
session of the National Diet during 1973. The provision in the Seto Inland-Sea
Conservation Law is a good example. This law stipulates that an application for
permission for building specific industrial facilities in the coastal areas of the Seto
Inland-Sea shall be accomplished with the statement of the results of the preliminary
evaluation made by the surveys on possible influences the proposed industrial facili-
ties may have on the surrounding environments. The law also stipulates that the
said document should be made available to public inspection for a period of three
weeks.
The general procedures for environmental impact assessment is shown in Fig. 1.
35
-------
Fig. 1 Procedures for Environmental Impact Assessment
Measures for
Environmental
Preservation
Development Project (alteration of
nature, housing, transportation, produc-
tion activities, etc.)
Formulation
of List of Survey
Items
Determination of
Survey Items
State of Survey Items
Environmenta
Load Forecasting
Model
Forecasted Environ-
mental Load Volume
i
r
Environmental
Change Forecasting
Model
Forecasted Environ-
mental Change
i
Environmental
Standards
Human Health
Nature
Conservation
Preservation
of Living
Environment
36
-------
FIFTH US/JAPAN CONFERENCE
ON
SEWAGE TREATMENT TECHNOLOGY
PAPER NO, 2
STUDIES ON STORN AND COMBINED SEWER
OVERFLOW
APRIL 26-28, 1977
TOKYO, JAPAN
MINISTRY OF CONSTRUCTION
JAPANESE GOVERNMENT
37
-------
STUDIES ON STORM AND COMBINED SEWER OVERFLOW
1. WATER QUALITY CHARACTERISTICS OF STORM & COMBINED
SEWER OVERFLOW 39
K. Takeishi, Ministry of Construction
2. COMBINED SEWER OVERFLOW SIMULATION
-CASE STUDY ON YABATA SEWER CATCHMENT AREA,
TOKYO- 69
T. Yamaguchi, PWRI, Ministry of Construction
38
-------
CHAPTER 1. WATER QUALITY CHARACTERISTICS OF STORM
& COMBINED SEWER OVERFLOW
1.1 Current Status of the Combined Sewer System in Japan 40
1.1.1 Combined Sewer System 40
1.1.2 On-going Measures and Research Activities for the Combined
Sewer Systems 40
1.2 Examples of Measures against Combined Sewer Overflow Problems 42
1.2.1 Storm Water Sedimentation Tank in Osaka 42
1.2.2 Storm Water Detention Trunk Sewer in Osaka 42
1.2.3 Storm Water Sedimentation Tank in Yokohama 42
1.3 Interim Results of Basic Surveys by the Research Committee on
Combined Sewer System Problems 43
1.3.1 Method of Survey 43
1.3.2 Outline of Survey Areas 43
1.3.3 Survey Results 45
1.4 Postscript . 68
39
-------
1. WATER QUALITY CHARACTERISTICS OF STORM & COMBINED
SEWER OVERFLOW
1.1 CURRENT STATUS OF THE COMBINED SEWER SYSTEM IN JAPAN
1 1.1 COMBINED SEWER SYSTEM
In Japan as of 1975, 583 municipalities had been practicing the sewage works.
In 1976, 65 new municipalities are expected to enter upon sewage works.
The population served by sewers in 1975 is estimated to have been 22.8% of
the total population.
In Japan those cities which have a long experience in the sewage works have
the combined sewer system. According to a 1972 survey conducted by the Ministry
of Construction, the combined sewer system accounted for 73% of the total sewered
area, covering 69% of the total sewered population.
As the problems of the combined sewer overflow come to the fore, the number
of cities adopting the separate sewer systems is on a steady rise in recent years.
The Ministry of Construction is also a strong promotor of the separate sewer
systems. Table 1.1 shows the changes in the past three years of the number of
municipalities by type of sewerage.
The many municipalities which have combined sewer system adopt the separate
sewer system in new sewered areas, so the share of the combined sewer system is
decreasing gradually. Nevertheless, the significance of the combined sewer overflow
on the contribution of pollution loads in waters has not yet been reduced at all. In
large cities where the sewerage is making a large step toward improvement through
secondary treatment, the contribution for water pollution by combined sewer over-
flow will be increased more and more.
Table 1.1 Relative Use of Combined Sewers of Local Governments
^~\_ Year
-\^^
Sewer systerrT^^^^
Combined sewer
Hybrid
Separate sewer
Total
1973
70
158
217
445
1974
52
176
287
515
1975
47
185
351
583
1.1.2 ON-GOING MEASURES AND RESEARCH ACTIVITIES FOR THE
COMBINED SEWER SYSTEMS
1.1.2.1 MEASURES FOR THE COMBINED SEWER SYSTEM
In Japan, little has been reported of examples taking radical measures against
40
-------
pollution caused by combined sewer overflow. Most of municipalities have been
bending their efforts for the expansion of sewer-served areas. Although they have
full knowledges on the problems the combined sewer system has, their efforts don't
reach to the measures against them.
In the major cities where the sewerage system has long been used, improvement
of overflow chamber and enlargement of sewer capacity are being pushed for-
ward in order to recoup shortage of the capacity of the existing sewer system and
to overcome the problem of reduced dilution ratio of wet-weather overflow. These
improvements, however, are still in the stage of local scale practice, and come no-
where near providing a meaningful way against the water pollution by wet-weather
overflow.
What is standing in the way of changing the combined system to the separate
system lies in the vast sums of money required, narrow width of road in densely
populated area, and the fact that storm water from storm sewer itself is polluted.
Converting to the separate system is not considered to be the best solution.
Most of measures taken or being planned to control the water pollution by
combined sewer overflow are either detention or sedimentation of wet-weather over-
flow.
A facility installed in Osaka is the only one example of this type now we can
see in Japan, except for two additional facilities which are now under construction.
All these three are touched upon briefly in the next section. Some new districts
which adopted combined sewer systems install storm water sedimentation basins in
their sewage treatment plants in order to overcome the problems of wet-weather
overflow.
1.1.2.2 Current Research Activities
For the purpose of studying the improvement measures for the combined sewer
system, the Ministry of Construction established an research organization named
"Research Committee on Sewer System Problems." The members of the Committee
consist of the engineers from the Ministry of Construction, the Japan Sewage Works
Agency, major municipalities and representative medium-sized municipalities. Of
these municipalities, eleven adopt the combined sewer system, and one the separate
sewer system.
The principal objective of this Committee is to investigate about the combined
sewer system in each municipality by standardized manners, exchange findings and
formulate practical improvement measures.
The Committee is scheduled to work from 1975 to 1980. For the first three
years, the Committee will bend their energies to collect data with emphasis on the
fact-finding survey.
The data obtained this way is significant not only for the improvement of the
combined sewer system, but also as a basis for the planning of future sewer system.
Section 3 summarizes the findings acquired by the Committee in 1975.
The Urban River Section of the Public Works Institute, Ministry of Construc-
tion, developed a water quality simulation model of the combined sewer system.
The mode which stands on the concept of the retention of pollution load gives the
pollutegraph from a given hydrograph.
41
-------
It is corroborated by application of this model to some drainage areas that the
simulated results agree well with actual measurements. The model is considered to
become a useful tool in assessing the improvement of combined sewer system
because it can estimate the pollutegraph from the hydrograph calculated by the
modified RRL method from the precipitation record.
The results of this study are discussed in the next chapter.
1.2 EXAMPLES OF MEASURES AGAINST COMBINED SEWER OVERFLOW
PROBLEMS
In Japan, there are not so many practical examples of measures to control
water pollution due to combined sewer overflow.
Briefed here are three examples in Osaka and Yokohama.
1.2.1 STORM WATER SEDIMENTATION TANK IN OSAKA
In 1975, the Osaka Municipal Government constructed storm water sedimenta-
tion tank consisting of two basins by taking advantage of the improvement work of
Nakanoshima Pumping Station at the center of the city. The dimension of each
basin is 3.5 m in width, 20.2 m in length and 4.5 m to 5.0 m in depth. In the future,
four additional basins will be constructed. When all these tanks are completed, the
storage capacity will become 2,000 m3 or worth 4.4 mm of rainfalls in the area.
This facility is the only one example in Japan of measures against wet-weather over-
flow.
1.2.2 STORM WATER DETENTION TRUNK SEWER IN OSAKA
In Osaka, innundation frequently visits lowlands because of marginal use of
catch basin and subsidence due to excessive use of ground water. In order to
solve this problem, installation of a new interceptor was planned and has been under
way since 1973.
Its major portion having an inside diameter of 6,000 mm will be installed 25 m
deep with the length of about 3 km, and will provide a storage capacity of some
80,000 m3 or worth 6.6 mm of rainfalls in the area.
This trunk sewer is planned to serve for the control of water pollution due to
wet-weather overflow without detriment to the original purpose of innundation
control.
1.2.3 STORM WATER SEDIMENTATION TANK IN YOKOHAMA
The Yokohama Municipal Government is in the process of constructing
storm water sedimentation tank consisting of eighteen 6.0 m wide by 35 m long by
6.0 m deep basins with a total capacity of 22,680 m3 equivalent to 6.4 mm of rain-
falls in the area.
The tanks are of the underground type, and their covered top is planned to be
an athletic ground open to the public. These tanks are expected to reduce the pollu-
tion loads by 10% or more in SS and almost the same degree in BOD as compared
with the separation device.
42
-------
1.3 INTERIM RESULTS OF BASIC SURVEYS BY THE RESEACH
COMMITTEE ON COMBINED SEWER SYSTEM PROBLEMS
1.3.1 METHOD OF SURVEY
For the purpose of collecting extensive data on the characteristics of wet-
weather combined sewage, twelve drainage areas different in drainage system and
land use were selected as the study areas in the eleven member municipalities. The
designated areas have already been perfectly covered by the combined sewer system,
have a sizable tract each, and also are favoured with conditions permitting hydraulic
and hydrologic analysis with ease.
In one city which has adopted the separate sewer system, a survey area
was also sited to fulfil similar conditions. A survey station was installed at the
downmost end of the sewer in each survey area for flow measurement and sampling.
At several spots in the survey area, rainfall gaging was also carried out. The sampled
water was subjected to analysis according to analysis according to the unified
methods.
In 1975, flow measurement and sampling were conducted one to two times in
dry-weather and two to four times in wet-weather in the combined sewer survey
areas and four times in wet-weather in the separate sewer survey area. In the
separate sewer municipality, the survey area was relocated in 1976 to a suburb
where three-times surveys were carried out in wet-weather.
In addition, geographical and social conditions, including land use patterns and
demographic status, were also investigated in each survey area.
1.3.2 OUTLINE OF SURVEY AREAS
The combined sewer survey areas are outlined in Table 1.2 (a), and the separate
sewer survey areas in Table 1.2 (b).
The following is a list of survey areas and a brief explanation of each.
Combined sewer survey areas
A: Single-family residential area apart from the city center
B: Populated urban area with a mixed consist of residential houses and stores
C: Area with a mixed consist of small to medium factories, residential houses and
stores
D: Area with residential zones and shopping quarters
E: Residential area on a terrace bordering on an unban area
F: Area with low-story and medium-story shopping quarters and amusement
quarters
G: Area with low-story shopping quarters, amusement quarters and medium-story
business quarters
H: Dense area packed with low-story residential houses, stores and factories
mainly of textile and dyeing
I: Typical high-story civic and business center
J: Area sited on a spit in the estuary, with residential quarters, and commercial
quarters, wholesale markets and small factories along a trunk road
K: Suburban residential area on a terrace with many company-owned residential
43
-------
Table 1.2 (a) Summary of Surveyed District (Combined Sewer System)
Drainage
district
A
B
C
D
E
F
G
H
I
J
K
L
Drainage
system
Pumping
Gravity
flow
Pumping
Pumping
Gravity
flow
Gravity
flow
Gravity
flow
Grayity
flow
Pumping
Pumping
Grayity
flow
Gravity
flow
Drainage
area
(ha)
44.33
540.6
269.5
35.13
22.09
68.37
39.5
148.49
45.50
215.14
57.6
17.61
Population
Daytime
6,655
165,019
58,690
12,298
3,579
38,268
12,800
37,180
43,200
27,000
3,973
9,700 (day)
17,000 (night)
Resident
4,016
155,091
61,167
9,003
4,270
8,358
1,780
25,280
804
31,727
3,863
1,098
Sewer
diameter
(mm)
300-
900
a 6000 x 4325
a 4000 x 3600
Q1650x 1650
250-
1200
230-
a 1950 x 1950
250-
1650
250-
a 3000 x 1930
300-
a 2000 x 1350
250-
a 2200 x 2200
200-
02100x 1680
230-
01360x 1060
Max.
flow rate
in dry-
weather
(m3/s)
0.057
2.11
1.57
0.10
0.052
0.282
0.189
0.809
0.385
0.261
0.028
0.247
Land use
Residential
(ha) (%)
44.33 100
397.5 73.5
16.79 6.2
21.45 61.1
21.38 96.8
0 0
0 0
32.10 21.6
0 0
108.54 50.5
57.6 100
0 0
Commercial
(ha) (%)
0 0
68.29 12.6
46.84 17.4
13.68 38.9
0.71 3.2
68.37 100
39.5 100
32.86 22.1
45.50 100
41.6 19.3
0 0
17.61 100
Industrial
(ha) (%)
0 0
74.80 13.9
205.87 76.4
0 0
0 0
0 0
0 0
83.53 56.3
0 0
65.0 30.2
0 0
0 0
Road area
(ha) (%)
6.95 15.7
116.6 21.6
3.82 1.4
4.46 12.7
2.39 10.8
21.05 30.8
9.80 24.8
31.27 21.1
24.3 53.4
44.77 20.8
7.0 12.2
5.35 30.4
Impervious area
(ha) (%)
15.27 34.4
288.0 53.3
186.3 69.1
16.08 45.8
7.68 34.8
55.43 81.1
31.02 78.5
114.46 77.1
39.1 85.9
127.95 59.5
15.0 26.0
16.40 93.1
-------
Table 1.2 (b) Summary of Surveyed District (Separate Sewer System)
Drain-
age
district
M
O
Drain-
age
system
Gravity
Gravity
flow
Drain-
age
area
(ha)
17.17
26.75
Population
Day-
time
9,300
2,420
Resi-
dent
2,695
3,227
Sewer
diameter
(mm)
ai200x
1030-
030x70
Q2500x
1800
Land use
Residen-
tial
(ha) (%)
8.55 49.8
26.75 100
Com-
mercial
(ha) (%)
8.02 46.7
0 0
In-
dustrial
(ha) (%)
0.60 3.5
0 0
Road
area
(ha) (%)
5.72 33.3
4.99 18.7
Imper-
vious
area
(ha) (%)
15.7 91.4
21.26 79.5
houses
L: Typical amusement quarters on a spit in the estuary, enticing extremely large
night population compared with daytime one
Separate sewer survey areas
M: Tier on the sea, with business quarters, commercial quarters, hotels, public
facilities, government institutions, multi-family residential houses
O: Newly developed residential area on a suburban terrace, with single-family
houses
1.3.3 SURVEY RESULTS
1.3.3.1 Water Quality Characteristics of Combined Sewer
Summarized in the following are the results of dry- and wet-weather water
quality survey made in 1975 of the twelve survey areas in the eleven municipalities
in different localities in Japan.
(a) Findings of Dry-weather Survey
In each survey area, dry-weather around-the-clock survey was carried out once
or twice. During the survey, sewage flow was measured and once-every-30 minutes
sampling were conducted for water quality analysis.
Table 1.3 shows dry-weather average water qualities and concentration
ranges in respective survey areas.
Followings are the water quality characteristics of respective survey areas in
dry-weather and the factor that are considered attributable to them.
C: Industrial quarters account for 75% of total area, discharging high concentra-
tions of heavy metals.
E: Residential, but high in BOD, COD and SS.
H: A good number of textile and dyeing factories in the area resulting high BOD,
COD and SS.
I: Typical business quarters discharging weak effluents having a soluble-to-total
BOD ratio of 14.4%.
K: Low BOD; quantities of pipeline desposits are suspected to be.
L: Densely built amusement quarters generating a large volume of sewage for the
area; high BOD.
While these areas have different characteristics, they also have something in
common with each other as follows.
45
-------
Table 1.3 Dry Weather Average Concentration of Combined Sewage
Drainage
district
A
B
C
D
E
F
G
H
1
J
K
L
Date
Oct. 22
-23
Jul. 15
Sep. 21
-22
Aug. 26
-27
Dec. 3
Sep. 2
-3
Nov. 11
-12
Aug. 27
-28
Oct. 23
-24
Jan. 12
-13
Oct. 31
Oct. 1
Aug. 4
~5
Feb. 2
Dry Weather Arerage Concentration ("ower Ra^ ^ mg/C
BOD
136
21-560
103
23-151
127
12-229
110
35-281
134
16-374
84.8
34.7-147
122
39.5-180
93.2
7.6-205
321
66-691
101
11-180
116
14-203
51.7
6.3-123
143
21.4-297
180
31-494
S-BOD
79.9
19-468
-
42.1
5.8-72.9
82.0
17-198
49.0
4-184
31.6
9.9-53.6
36.4
10.1-63.2
47.6
4.4-132
208
44.3-311
14.5
4.0-29.3
68.4
10.6-152
18.5
4.5-43.0
56.3
10.7-109
-
COD
37.2
6.2-158
-
53.0
10.0-136
60.0
24-191
117
15-293
41.1
11.9-67
35.6
23.2-56.1
38.9
8.7-63
232
35-359
45.6
16.3-75.7
74.2
17.3-148
32.5
7.8-79.5
47.9
14-80.4
70.1
15.8-150
SS
55.0
14-163
83.2
12-157
88.3
12-205
84.8
19-258
202
8-844
76.0
26-184
79.0
27-132
64.0
13-125
120
22-194
95.7
19-202
78.2
12-187
55.8
10-145
107
35-540
100
18-203
vss
40.0
3-128
-
60.9
3-123
60.8
7-230
129
8-388
51.9
26-90
54.2
21-104
53.9
10-104
86.3
19-129
60.4
14-109
57.0
10-140
46.5
6-120
52.0
15-214
-
T-N
15.8
ND-40.6
-
14.7
5.17-27.7
21.5
12-52
21.3
10.6-60.1
12.4
5.49-21.1
13.8
6.8-28.8
11.5
3.0-18.0
15.3
9.56-29.7
17.9
1.60-30.7
21.5
11.2-47.4
11.0
4.1-35.0
15.2
4.32-26.4
22.0
5.97~32.S
T-P
4.14
0.11-18.8
-
4.31
0.94-8.24
2.05
1.0-5.5
5.20
1.6-12.5
4.13
1.4-8.7
4.06
1.6-7.6
1.46
0.29-2.20
5.04
2.08-8.20
2.57
1.01-3.42
10.6
2.7-23.1
; 3.08
1.13-7.32
2.27
0.95-3.24
3.13
0.85-5.13
Zn
0.02
ND-0.08
-
2.23
0.16-9.13
ND
0.30
0.07-0.65
0.25
0.15-0.47
0.15
0.11-0.22
0.19
0.09-0.40
0.663
0.10-1.51
0.12
ND-0.20
1.5
0.05-27
0.08
ND-0.6
0.18
0.09-0.49
-
Cu
0.017
ND-0.58
-
0.844
0.02-10.2
ND
0.03
ND-0.08
0.057
0.02-0.14
0.04
0.01-0.07
0.037
ND-0.15
0.079
0.02-0.16
0.05
ND-0.07
ND
0.013
0.007-0.025
0.02
ND-0.16
-
Pb
ND
-
0.04
0.01-0.09
ND
0.006
ND-0.05
0.01
ND-0.03
0.01
ND-0.03
ND
0.01
ND-0.04
ND
ND
ND
ND
-
Coliform
group
x 104/mC
2.91
0.05-14
-
-
80
20-280
5.18
0.5-26
6.4
1.2-9.7
6.5
2.8-9.2
77
21-260
2.4
0.011-11
17
1.5-40
5.7
1.6-20
11
0.52-38
80
1.1-820
-
-------
a. VSS/SS is in the range of 0.63 to 0.88, except for one survey area.
b. Three survey areas (F, G, and L) show flow rate 10 to 30% less in winter than
in summer, and an increase in BOD of 30 to 40% on the average in winter over
summer.
c. No definite differences by land use are noticed
Table 1.4 shows daily flow and loadings per capita discharged. In Japan, it has
been generally accepted as a sewage works planning practice that the sanitary sewage
volume and BOD load per day per person are about 500 lit. and 60 g, respectively.
It is noteworthy that even in typical residential areas such as A and E, these standard
values are exceeded by a large margin.
Table 1.4 Summary of Per Capita Runoff Loadings
(Per capita per day)
District
A
B
C
D
E
F
G
H
1
J
K
L
Popula-
tion*
5,335
160,055
59,929
10,650
3,924
23,313
7,290
31,230
22,002
29,363
3,918
9,266
Flow
(2)
738
661
1,583
536
702
711
510
882
1,155
429
487
356
1,352
1,258
BOD
(g)
100
68.1
202
59.9
93.6
60.4
62.3
82.2
367
43.4
56.6
18.3
192
226
SS
(g)
40.7
55.0
140
46.6
140
55.3
40.5
56.2
140
41.1
38.6
19.7
145
126
K-N
(g)
11.7
-
23.3
11.8
-
9.09
7.21
10.2
18.1
7.68
10.5
3.94
20.5
-
T-P
(g)
3.05
-
6.82
1.13
3.78
3.05
2.15
1.29
5.88
1.10
5.35
1.09
3.06
3.93
(Sep. 2-3)
(Nov. 11-12)
(Aug. 4-5)
(Feb. 2)
* Average of Daytime and Resident Population Shown in Table 1.2 (a).
(b) Findings of Wet-weather Survey
Wet-weather survey was conducted two times to four times in each survey area.
i) Wet-weather runoff and water characteristics
Fig. 1.1 shows the relationship between total rainfall and total runoff. The
runoff coefficient is largely influenced by the impervious area ratio. As shown in
Table 1.2, some survey areas have a large impervious area ratio of more than 90%.
In these areas, the runoff coefficient is high. Taken altogether, however, the runoff
coefficient lies in the range of 40 to 80%.
Table 1.5 shows average characteristics and concentrations of combined sewage
in wet-weather conditions.
Figs. 1.2 (a) through (d) show wet-weather BOD, SS, T-P, and K-N in terms of
47
-------
Table 1.5 Summary of Average Quality of Combined Sewage in Wet Weather
Dis-
trict
A
B
C
0
E
F
a
H
1
J
K
L
Date
1
2
1
2
1
2
3
1
2
3
I
1
3
1
2
3
1
2
3
4
1
2
3
1
2
3
1
2
3
1
2
1
2
3
Nov. 15
-16
Nov. 27
Jul. 10
Jul. 12
Sept. 23
-24
Sept. 29
Nov. 14 .
-15 '
Oct. 3
Nov. 19
Feb. 5
Oct. 24
Feb. 5
Feb. 16
Oct. 7
Oct. 24
Nov. 7
Aug. 22
Sep. 8
Sep 18
Oct. 7
Jul. 7
Aug. 6
Feb. 5
Oct. 28
-29
Nov. 6
-7
Nov. 27
Feb. 5
Feb. 18
Mar. 11
-12
Oct. 7
Nov. 13
Nov. 18
Feb. 5
Feb. 17
Rainfall
(mm)
26.5
1.0
6.5
8.3
52.0
36.0
9.1
2.25
18.50
11.07
6.5
29.0
33.0
85.8
23.1
40.1
2.5
5.0
2.5
5.0
15.5
24.0
14.2
19.5
36.0
8.0
1.0
18.0
11.0
12.5
9.5
6.0
2.8
27.0
Wet Weather Average Concentration
-------
Fig. 1.1 Total Runoff and Rainfall
o!2
OH1
0H3 OF2
OI3M, ° ^002
"i3oKl °J2
0L1
O H2
= 11 OA1 0E3
OM2_,_. oE2
40 50 60
Total rainfall (mm)
90
Fig. 1.2 (a) Discharge Volume and Average Concentration (BOD)
OA2
OG2
0L2 0103
- -fi-°-o-
OD1
C3
LP* .
G4
O
OK2
BOD
OKI
J3
O
Oil
L3 D3
OI2
OJ2
13 OD2
OE3 OH2
OI-2
OF3
OF1
10 11 12
Discharge volume during wet-weather
Discharge volume during dry-weather
49
-------
Fig. 1.2 (b) Discharge Volume and Average Concentration (SS)
Dl
OL1
QA2
OK2
OG4
OG2
OG3
OJ1
OOG1
:3 .H?°QP.30.H1
OKI
Al J3
O O
OH2
OD2
-Fc5.
"Oil
OF2
SS
QJ2
012
OF3
12
Discharge volume during wet-weather
Discharge volume during dry-weather
Fig. 1.2 (c) Discharge Volume and Average Concentration (Total-P)
2.0
1.8
1.6
1.4
1.2
0.8
0.6
0.4
0.2
0
•
D
Total-P
^
P°"
OG3 °K2
« _I3___ . _..
0 ,3
OL1
QE3 Al J3 QD2
OC3 H3 O o
OE2LfO'l OKI 0]2
OF1
OD3 QF3
* OC1 OJ2
QH1
OF2 OH2
12
Discharge volume during wet-weather
Discharge volume during dry-weather
50
-------
Fig. 1.2 (d) Discharge Volume and Average Concentration (K-N)
2.6
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
OK2
Kjeldahl-N
OA2
OJ1 0"
L2
5fel <->H3
On
OL1 oil OK1
^il OG2 HI OH2 012
OE2 00 OJ3
q 9D3 A1
°E3 0 K2 OF1 01-3
OD2
_ OJ2
OG4
Discharge volume during wet-weather
Discharge volume during dry-weather
ratios to those in dry-weather. After a light rainfall, BOD, T-P and K-N become by
some chance by far larger in concentration than in dry-weather. In case of a large
scale storm, however, the concentrations are reduced by dilution effect and the
loadings are generally held within several times those in dry-weather. As regard SS,
however, the reduction of concentration is far less than others even in case of a
large-scale rainfall. Namely, it remains almost the same as in dry-weather. This
shows that the bulk of SS is conveyed into the sewer from the ground surfaces with
unlimited sources of SS supply.
Fig. 1.3 shows the relationships between maximum storm water flow rates and
runoff loadings of BOD and SS.
Although the runoff loadings of BOD and SS are different by an order or so
among the survey areas, it is found that they have a significant relationship with
flow rate.
As is clear from above, the mean values of most of water qualities can be said
to decrease with increase in the scale of rainfall. However, the time change in runoff
loadings is quite complicated, and defies rendition by mean qualities only.
Most of wet-weather records give the so-called "first flush."
Fig. 1.4 refers to the record in the survey area E in which the cumulative flow
and cumulative loadings are shown in percentage.
It is highly suggestive of a large loading runoff in the early stage of rain runoff.
It should be noted however that compared with BOD and SS, the loading
51
-------
Fig. 1.3 (a) Maximum Flow Rate and BOD Loadings Discharged
H3
°OB1
o G2
OKI
Maximum flow rale (m3/tec)
Fig. 1.3 (b) Maximum Flow Rate and SS Loadings Discharged
Mnimum (low tile (m]/tcc)
52
-------
Fig. 1.4 Cumulative Flow Volume and Pollution Loadings Discharged
A district (Wet-weather)
16:00 20-00 000 400
8-00 1200
g.
1
|
5. SO
BOD
SO
Cumulative flow discharged
IOOOO 11427(m3)
50
Cumulative Dow discharged
3993(m')
53
-------
Fig. 1.5 (a) Variation of Water Quality in Combined Sewage (Dry-Weather)
Fig. 1.5 (b) Variation of Water Quality in Combined Sewage (Wet-Weather)
o
=? 05
BOD/COD
VSS/SS
S-BOD/BOD
2.0 §
19.00
Time
54
-------
runoff curves of T-P and K-N do not show so large a change with time, and this
tendency is seen in most of rainfall observations. Hence it is inferred that the deten-
tion of wet-weather overflow by the storage tank in order to reduce pollution of
waters will be ineffective in the removal of T-P and K-N as compared with BOD and
SS.
Figs. 1.5 (a) and (b) show changes in water quality indices in the survey area K
during dry- and wet-weather, respectively. With reference to dry-weather, BOD/
COD, VSS/SS, S-BOD/BOD all are nearly constant in the daytime.
In the nighttime when the flow declines, VSS/SS decreases while S-BOD/BOD
increases. On the other hand, BOD/COD does not show so conspicuous change.
In wet-weather, every index shows a large change: in the rising period of runoff,
S-BOD/BOD declines; in the first peak of SS runoff, VSS/SS shows no change, but
in the second peak of SS when the sewage runoff has attained a maximum, VSS/SS
falls largely.
The decrease in VSS/SS is considered due to supply of SS from ground
surfaces.
With attention paid to the fact that VSS/SS is almost constant in dry-weather
while it changes in wet-weather, a trial is made to divide SS runoff loading into
ground-contributed component and the sewer deposit-contributed component
which is supplied during dry-weather.
From the urban storm water discharge survey shown in 1.3.3.2, the ground-
contributed SS is estimated at 0.2 in terms of VSS/SS.
The results of computation are shown in Fig. 1.6.
The first peak showing "first flush" is chiefly contributed by SS runoff from
the deposits in the sewer. In the second peak, however, SS is divided almost equally
between the deposit component and ground component. With reference to the
rainfall shown in Fig. 1.6, the ultimate SS discharge of 674 kg is broken down as
follows.
408 kg (61%) by sewer deposit runoff; 240 kg (36%) by ground supply; and
26 kg (3%) by sewage. Namely, the sewer deposit is found most responsible for SS
discharge.
ii) Local characteristics
From the viewpoint of locality, what shows the most highest change in wet-
weather as compared with dry-weather is the survey area K. In the second rainfall
observation in the survey area K, for example, the average concentration is 2.7 times
in BOD as much as that at the same hours in dry-weather, 5.6 times in SS as much,
and the runoff loading is 10.5 times and 21.8 times, respectively.
The maximum concentration is 840 mg/fi for BOD, and 2,129 mg/fi for SS.
As shown in 1.3.3.1, the dry-weather concentrations in the survey area K are
very small compared with the average concentrations in other survey areas. It is
therefore conjectured that a considerable amount of loadings is deposited in the
sewer during dry-weather and is flushed out in wet-weather to develop a salient
increase in the loadings.
The survey area K is situated on a steep with a ground slope of 24.5%0.
Considering this high slope, it is very queer why such deposit is developed in the
55
-------
Fig. 1.6 Comparison of Solids in Wet Weather Sewage by Sources.
K district Nov. 13. 1975
100
80
60
40
20 -
15:00
/\
A V \
SS, (Solids in dry weather sewage)
SS, (Solids accumulated in sewer)
SSj (Solids from surface in wet weather)
(g/sec)
1.2
\>--=,
17:00
19:00
21:00
23:00
Time
-------
sewer. The clarification of the causes is left to further study in the future.
In contrast to the survey area K, the survey area E which forms also residential
quarters on a steep slope of 20.4%0 shows only a bit increase in the wet-weather
runoff loadings. In the first rainfall observation in survey area K, for example, the
average concentration is 0.78 times in BOD and 1.02 times in SS as much as that
in the dry-weather and the runoff loadings also remain small.
As explained in 1.3.3.1, it is worth noting that in the survey areaK, SS, COD,
etc. are considerably high in dry-weather sewage.
For all that the survey areas K and E are almost the same in land use and
geographical conditions, they present quite different phases both in dry- and
wet-weather pollutant discharges. In the survey area K, it is no doubt that there is
something promoting deposition in the sewer.
It is therefore hoped that the causes be clarified to reflect in the engineering of
sewage pipeline system.
iii) Correlation between water characteristics
Figs. 1.7 (a), (b) and (c) show the correlation between the characteristics
obtained by the analysis of both dry- and wet-weather surveys. Here are some in-
teresting findings.
In many survey areas, the ratio VSS/SS becomes smaller in wet-weather than
in dry-weather, and the inorganic suspended solids increase in wet-weather.
From the correlation between BOD and TOC, it is understood that the
refractory organics increases in wet weather.
This is very important in dealing with the treatment of wet-weather combined
sewer overflow.
Of the heavy metals, zinc is found in every survey area. In many survey areas,
it is found that zinc has a significant correlation with SS, though no substantial
difference is seen between dry- and wet-weather.
1.3.3.2 Characteristics of Urban Storm Water Discharge
Aside from the water pollution due to combined sewer overflow, the urban
storm water discharge has come to be more and more recognized as a major con-
tributor of water pollution.
In the separate sewer municipality, member of the Research Committee on
Combined Sewer System Problems, a survey area was established for investigating
urban storm water discharge. Survey stations were set at the storm sewers in the
survey area M forming commercial quarters in the center of city in 1975 and in the
survey area O forming newly developed suburban residential quarters in 1976, for
the purpose of wet-weather storm water sampling and discharge observation.
(a) Local Characteristics
Table 1.6 shows the mean characteristics and concentration ranges of urban
storm water discharges observed at the two survey areas. In the survey area M where
amusement quarters exist, the water quality is very poor; the concentration on the
average of four rainfall observations were 38.9 mg/C for BOD, 288 mg/C for SS.
The maximum values were 309 mg/C and 1,180 mg/C, respectively, suggesting that
the urban storm water discharge itself is considerably contaminated.
57
-------
Fig. 1.7 Correlation between Water Qualities
* Dry-weather
° Wet-weather
240
1
A'district
(a) SS - VSS
100 200
300 400
SS (rng/C)
Dry-weatiier
Y = 0.8697X - 8.889
R = 0.990
Wet-weather
Y = 0.3807X+2.738
R = 0.927
600 700
* Dry-weather
o Wet-weather
L district
(b) BOD - TOC
—I—
160
—I—
240
Dry^weather
Y =0.3289X +6.378
R = 0.869
Wet-weather
Y = 0.5075X+ 14.49
R - 0.903
—I—
400
—I 1 1
480 560
BOD (mg/ii)
100 200 300 400
SS (mg/C)
Dry-weather
Y = 0.0076X-0.1669
R ° 0.868
Wet-weather
Y = 0.0046X + 0.2788
0R = 0.761
500 600
~T 1
700
58
-------
Table 1.6 Summary of Storm Runoff Water Quality from Urban Area
Dis-
trict
M
O
Date
1
2
3
4
1
2
4.6
8.6
9.8
12.4
7.19
10.20
Rain-
fall
(mm)
8.0
19.5
11.0
8.0
27.0
9.0
Wet Weather Average Concentration ({^ww: fUngT^ mg/E
BOD
56.7
7.2-142
32.1
6.9-
309
30.5
12.5-
72
62.2
9.7-
114
1.2-
12.6
2.5-
16.1
S-BOD
11.1
5.6-
17.9
9.24
4.0-
47.4
7.69
6.4-
12.5
14.3
6.1-
42.3
0.9-
3.5
1.3-
4.2
COD
43.9
9.9-
77.1
43.7
10.5-
190
40.7
17.5-
73.5
50.8
10.4-
80.8
5.1-
25.0
7.7-
25.0
SS
420
10.4-
863
303
1.1-
1180
347
20-
715
182
16.3-
280
38.0-
490
16.3-
153
VSS
91.9
4-
226
98.1
9.3-
460
71.2
14.2-
101
95.6
~
148
8.0-
61.0
7.0- •
35.0
T-N
7.23
3.75-
18.8
5.31
1.7-
25.9
3.45
2.62-
3.77
8.81
2.28-
14.9
1.17-
4.27
1.18-
7.46
T-P
0.24
0.053-
0.556
0.24
0.09-
1.45
0.41
0.36-
0.89
0.48
0.09-
1.73
0.01-
0.24
0.009-
1.42
Zn
0.956
0.11-
1.75
0.670
0.06-
1.80
0.54
0.19-
0.70
0.734
0.12-
1.07
0.042-
0.286
0.038-
0.250
Cu
0.149
0.030-
0.36
0.299
0.026-
1.93
0.12
0.01-
0.14
0.136
0.031-
0.192
0.004-
0.019
0.0067-
0.022
Pb
0.277
0.028-
0.740
0.212
0.015-
0.550
0.101
0.018-
0.130
0.114
0.015-
0.151
0.010-
0.055
0.0099-
0.034
Cr
0.025
0.004-
0.046
-
-
-
0.002-
0.009
0.0006
-0.0018
Ni
0.038
0.006-
0.057
0.021
0.004-
0.073
0.018
0.006-
0.022
0.019
0.008-
0.027
0.004-
0.013
0.0011-
0.045
Cd
0.0031
0.0014-
0.0103
-
-
-
0.0006-
0.0017
0.0005
-0.0020
Coliform
Group
x 104/m2
0.74
0.037-
4.0
0.38
0.081-
6.2
0.46
0.011-
0.71
0.88
0.042-
1.5
0.057-
0.76
0.22-
0.76
-------
Fig. 1.8 shows the third rainfall observed in the survey area M. It also shows
the relationship between the cumulative loadings of BOD, SS, T-P and K-N in
percentage to the respective totals and the cumulative discharge.
The loading hydrograh shows a bell shape, significant of a large loading runoff
in the initial stage of rainfall. Just as in Fig. 1.4, however, T-P and K-N are less in
such tendency.
Figs. 1.9 (a) and (b) show the changes in water quality in the two survey areas.
While the water quality in the survey area M is very poor, that in the survey
area O is very agreeable, proving that the water quality of storm water discharge is
largely governed by the local conditions. In such a place as the survey area M where
the social activities are vigorous, the effect of storm water discharge on the pollution
of waters cannot be neglected, and the separate sewer system may have to be
improved some way or other in the future.
Fig. 1.8 Cumulative Flow Volume and Loadings Discharged of Urban Starm Water
M district Sep. 8, 1975
SS BOD
nig/l! mg/t
800 -
400 -
0 J
80-
40-
Rainfall
(mm/5 min)
0
-2.0
-4.0
13:35
14:00
15:00
15:25
500
Cumulative flow discharged (m3)
1182
60
-------
Fig. 1.9 (a) Variation of Water Quality in Storm Water Discharge (Urban Area)
BOD 0
mg/C mVsec
M district Dec. 4, 1975
150
100
50
-0.10
•0.10
0.05
ss
mg.lv
300
200
100
1.0
0.5
21
-------
Fig. 1.9 (b) Variation of Water Quality in Storm Water Discharge
(Residential Area in the Suburbs)
BOD 0
mg/8 m3/sec
20 Lc
10
1-0.1
O district Oct. 21,1976
6:00
7:00
8:00
ss
mg/C
200
100
9:00
1.0
0.5
BOD/COD
(BOD-S-BODVVSS
VSS/SS
6:00
7'00
8:00
9:00
1.0
a
O
BOD/TOC
BOD/TOD
. S-BOD/BOD
12.0
a
o
0.5
I 1.0
6:00
7:00
9:00
62
-------
(b) Characteristics of Water Quality
Fig. 1.10 shows the nitrogen forms in the urban storm water disclosed by the
survey of the survey area M.
As the discharge comes close to an end, the ratio of NH3-N is reduced, while
NO2-N and NO3-N rise.
Fig. 1.11 shows the correlation between SS and VSS on the one hand arid
heavy metals on the other.
Interestingly enough, the ratio of VSS/SS is smaller than that in the combined
sewer.
There is a significant correlation established between SS and heavy metals.
Assuming that all these heavy metals are present in SS, a comparison between them
and the heavy metal concentrations usually found in soil shows that Zn, Pb and Cd
in SS are more than 50 times those in natural state.
Fig. 1.10 Variation of Nitrogen Forms in Urban Storm Water Discharge
M district Apr. 6, 1975
O K-N
• NO, -N
A NO, -N
(mg/C)
0.20
(rag/1!)
2.0
63
-------
•a
640 -
480 -
320 J
160 -
Fig. 1.11 (a) Correlation between SS and VSS
(a) SS-VSS
o o
Y = 0.3360X+ 15.96
R = 0.830
200
400
l
600
800
1000
1200
l i
1400
Fig. 1.11 (b) Correlation between SS and Heavy Metals
SS (mg/C)
1.60 -
1.20-
r5 0.80 -
0.40
0.00
Y =0.0017X + 0.2281
R = 0.872
600 800
SS (mg/C)
1000
1200 1400
64
-------
Fig. 1.11 (c) Correlation between SS and Heavy Metals
0.80 -
0.60 -
: 0.40 -
0.20 -
0.00
(c) SS-Pb
Y = 0.0005 x+0.0305
R = 0.806
200
400
600 800
SS (mg/E)
1000 1200
1400
Fig. 1.11 (d) Correlation between SS and Heavy Metals
Y = 0.00005 + 0.0033
R = 0.987
0.004
—i r
640
i r
480
800
960
SS (mg/E)
1120
65
-------
Fig. 1.11 (e) Correlation between SS and Heavy Metals
0.068-
Y = 0.00005 X +0.0114
R = 0.736
0.004
—i r
600
SS (mg/B)
—I T
800
1000
"1 1 T
1200
1400
Fig. 1.11 (f) Correlation between SS and Heavy Metals
0.0094 -
0.0074 -
I
S 0.0054
0.0034
0.0014
Y = 0.00001 X +0.0014
R = 0.962
~iI r
160
320
480
SS (mg/K)
—1 1 1 1 1 1 1
640 800 960 1120
66
-------
(c) Characteristics of Rainfall
Table 1.7 shows the results of rainfall analysis made in the survey area M.
In the urban area, the rainfall itself is fouled with air pollutants, including
poisonous heavy metals such as Pb and Cd, posing serious threat to human health.
Table 1.7 Water Quality of Rainfall
M District April 6, 1975 Rainfall 8 mm
\
\
\
Concen-
tration
(mg/8)
Load
(g/ha)
COD
4.04
323
T-N
0.885
70.8
K-N
0.53
42.4
NO;-N
0.0125
1.0
N03-N
0.343
27.4
T-P
0.044
3.48
Total
residue
on
evapora-
tion
79.2
6330
Volatile
22.2
1770
Zn
0.014
1.14
Cu
0.013
1.04
Pb
0.0185
1.48
Cr
0.0026
0.208
Ni
0.0065
0.520
Cd
0.0006
0.048
Fig. 1.12 shows the relationship between rainfalls and average concentrations
which is obtained by analyzing the quality of rainfall in Tokyo. It is considered that
the concentrations of rainfall decline with increase in rainfall to eventually saturate
to a constant value.
The results of the surveys in the survey area M and in Tokyo are in agreement
so long as the order of values is concerned.
(mg/S)
7
z
I
X
z
z
I
o
z
I
o"
z
• •
o
o
o
Fig. 1.12 Rainfall and Water Quality
O
o
• NH,-N
APO.-P
A
10
20 30 40
Total rainfall (mm)
A
O
50
O
(mg/C)
0.06
0.05
0.04
0.03
0.02
0.01
O
a.
67
-------
1.3.3.3 Summary of Survey Results
The surveys on combined sewer overflow and urban storm water discharge in
the twelve representative cities in Japan have disclosed the following.
1) It is generally seen in wet-weather that BOD, T-P and T-K are diluted signifi-
cantly while SS remains no nearer being diluted.
2) Wet-weather discharge of T-P and K-N has less to do with the tendency of "first
flush" than BOD andSS.
3) In wet-weather, the water quality in the combined sewer gets aggravated
seriously, largely different though they may be with locality.
4) In wet-weather the combined sewer experiences an increase in inorganic SS and
at the same time an increase in refractory organics.
5) The urban storm water discharge quality varies depending on land use; the
discharge from urban areas such as amusement quarters is seriously contaminated.
6) In the urban area, the storm water itself is polluted; the degree of pollution is
high, particularly in the early stages of precipitation.
1.4 POSTSCRIPT
A series of surveys of which this is part will be continued till 1973 for collect-
ing more detail data which the authors are confident will provide something of a
basis on which to build up more improved sewer systems meeting specific conditions
of localities.
68
-------
CHAPTER 2. COMBINED SEWER OVERFLOW SIMULATION - CASE
STUDY ON YABATA SEWER CATCHMENT AREA,
TOKYO -
2.1 Introduction 70
2.2 Overflow Quality Characteristics 70
2.3 Field Survey of the Pollutants on the Source 76
2.4 Simulation of BOD Load Discharge 77
2.4.1 Relationship between Discharge Q and Pollutant Load Discharge Qs . 77
2.4.2 Introduction of Basin Residue Load (S) 78
2.4.3 Equation of Continuity 78
2.4.4 Initial Conditions (S0) 78
2.4.5 Results of Simulation 79
2.5 Problems and Future Prospect 85
2.5.1 Problems 85
2.5.2 Future Prospect 85
Acknowledgement 86
Appendix 86
69
-------
2. COMBINED SEWER OVERFLOW SIMULATION - CASE STUDY ON
YABATA SEWER CATCHMENT AREA, TOKYO -
2.1 INTRODUCTION
A brief mention will be given hereunder to the problem of pollutants overflow
from combined sewers. As is well known, the combined sewer transports domestic
waste water to the sewage treatment plant during dry weather, and during storm
weather, stormwater is added to the domestic waste water. It is impossible, how-
ever, to send all the water to the sewage treatment plant because of its limited
capacity. Therefore, if storm water flow exceeds a discharge that is two or three
times as much as dry weather flow, the excess is all discharged into the river. Origi-
nally, it was considered that no harm would result, since the pollutants overflow was
diluted to some extent; but upon execution of such a method, it was found that
more polluted water than dry weather flow owing to released deposits on the sewer
was discharged into receiving waters. Regarding the magnitude of the problem, it is
said in the United States that the released pollutants load by storm water into re-
ceiving water should be more or less equal to those from the secondary treatment
plant (in terms of BOD). Because of this, the Japanese government is now directing
cities to install separate sewers. However, since sewers in existing major cities like
Tokyo, Nagoya and Osaka are of the combined sewer type, this problem has recently
been taken up to be solved. Nevertheless simulation of pollutants overflow was
scarcely attemped in the past, because the pollutant runoff pattern itself occurred
not in a simple manner; and so far no adequate measures have been taken up.
The Urban River Section of River Division, Public Works Research Institute,
has been carrying out the investigation of storm water runoff from the urban area
since its inception 1969 with the cooperation of the Tokyo Metropolitan Govern-
ment. From 1972 onward, the section has also been sampling and analyzing com-
bined sewer overflow. Fortunately, the section was able to propose the simulation
model of storm water runoff in 1973 and succeeded in the simulation of the pollu-
tants runoff in 1975. Although the betterness of fit of the simulation still requires
to be ascertained by applying it to the other basin, it has been decided to report on
the simulation as it is at the present stage, to solicit the criticism of readers.
It may be necessary to be added here that the present report is concerned only
with BOD.
2.2 OVERFLOW QUALITY CHARACTERISTICS
Since there are many detailed reports on the characteristics of overflow from
the combined sewer, only their essence is extracted here for lack of space.
First, Fig. 2.1 ~ 2.3* show examples of observed hydrograph, pollutograph,
* The peak discharge of 49 m3/sec. On 10th November, 1973 in Fig. 2.2 is nearly equal to the
design discharge.
70
-------
and concentration of BOD at the Yabatagawa Basin. In these figures, it may be
pointed out that conversion from rainfall to runoff (Q: m3/s) indicates comparatively
simple correspondence, but then the relation between the concentration of BOD
(C: mg/1) and BOD load discharge (Qs = CQ: g/sec) is somewhat complicated. As a
result, sampling intervals, from the initiation of runoff to the peak is short. For
comparison, patterns during dry weather are also indicated by broken lines.
Fig. 2.1 Example of Observed Overflow Characteristics {Yabatagawa, Tokyo)
R (mm/hr)!
20-
Aug. I, 1973
Rainfall intensity
Aug. I, 1973
Observed discharge
Dry weather flow
Observed BOD load discharge
IS 16 17 18 19 /\ 20 21 22 23
9 10 II 12 13
r/\
Observed concentration / *
Dry weather con- /
Observed concentration of SS
Dry weather concentration of SS
Observed SS load discharge
Dry weather SS load discharge
14 15 16 17 18 19 20 21 22 23 24 123456789 10 11 12 13
71
-------
Fig. 2.2 Example of Observed Overflow Characteristics (Yabatagawa, Tokyo)
R (mm/hr)
100 -.
50
Nov. 10, 1973
Rainfall intensity
Q
40
30
20
10
BOD
(mg/C)
300
BOD
(g/s)
1600
Nov. 10, 1973
Observed discharge
Dry weather flow
Observed concentration
Dry weather concentration
Observed BOD load discharge
Dry weather pattern
-------
Fig. 2.3 Example of Observed Overflow Characteristics (Yabatagawa, Tokyo)
Q BOD
(m3/s)(g/s)
5 -
Aug. 24, 1973
July 12, 1973 (Dryweather)
16 17 18 19 20 21 22 23 0 1 234
13 14
14
15
16 17 18 19 20 21 22 23 0
-------
These exmples clearly show the high BOD concentration at the initial period
(so-called "first flush") and the condition in which BOD load discharge does not
decrease even if the magnitude of runoff increase (this condition cannot be ex-
plained by dilution alone). As for the reason, a concept is generally accepted that
deposits accumulated on the sewer during dry weather are transported by storm
water. In this respect, the Report on Storm Water Investigation at Northampton*
is famous for verifying this concept by discharging a large quantity of clean water
into the sewer during dry weather. Pollutants from the ground surface will be dealt
with in Chapter 2.3.
The observed values of BOD load discharge are plotted with Q on a loglog
scale according to the sequence of observations, and the curve naturally indicates a
clockwise loop (Fig. 2.4 ~ 2.6). This phenomenon is understood to be the result of
a decrease in the pollutant load deposited in the sewer (S), by storm water.
Fig. 2.4 BOD Load Discharge ~ Q
(Yabatagawa, Tokyo)
Aug. 4. 1973
Q
(m'/s)
This report is one of the classics on this problem and worthy of a perusal.
74
-------
Fig. 2.5 BOD ~ Q (Yabatagawa, Tokyo)
Fig. 2.6 BOD ~Q (A city)
Q(m'/s>
BOD
(I/I)
-1000
- 800
— 600
200
— 100
40
Aug. 6, 1975
47
° C
4
P
c
k
•MI
°44
£5
'V
17
0,, /
V ^
38^
r/0
15^Q3
O\_
p1^
0)0°
X
27
CK
A
0
x
1
N
0i
05"
22
3
Another important phenomenon is that the pollutant load discharge during
about one or two days after the termination of runoff becomes smaller than the dry
weather load discharge. Considering that this phenomenon was found in older
records, the author sampled and analyzed the load discharge for 12 to 24 hours
after the termination of runoff in fiscal 1973 and this phenomenon was observed in
every example analyzed. For the interpretation of this phenomenon, variation in
the dry weather load can be considered, but according to the result of observations
so far conducted, the dry weather pattern is comparatively stable, if a season is
fixed. Therefore, the cause of the phenomenon is considered to be re-accumulation
of dry weather load, that is, the recovery of the deposits. This accumulation may
occur in the following way: Judging from the fact that the accumulation also seems
to occur during later stage of runoff, it is inferred that gravel mounds and pits
located on the sewer pipe act as a sort of load accumulation potentials, and even if
the discharge at the later stage of runoff is a little greater than dry weather flow,
pollutant load may accumulate on the gravel mound and in the empty pits on the
sewer pipes. This can be easily understood if you imagine gravel pits of catch basins.
Finally, as for the pollutant load balance for one rainfall or during a certain
period, 10 days' continuous water sampling and analysis were carried out for fiscal
1974 and 1975 on the basis of the survey results for fiscal 1973. The result of the
field survey for fiscal 1974 is shown in Fig. 2.7. Regarding BOD, the pollutant load
is more or less balanced, if+4.87 tons for about 1 day from 3rd to 4th July, 1974 is
ignored. The same results were obtained in the survey for fiscal 1975. From the
above, it is observed that pretty high accuracy can be expected of the simulation of
BOD, even if supply of pollutants from the ground surface is ignored.
75
-------
Fig. 2.7 Comparison with Dry Weather by 10 Days Observation
(Yabatagawa, Tokyo)
BOD,
(E/s)
150
+ 1.02
Hatched: BOD load due to storm runoff
Unit: ton
16 I! 19 12 2024
7/4
July 4
7/5
7/6
7/7
7/8
7/9
7/10 7/M
7/12
7/13
July 13
2.3 FIELD SURVEY OF THE POLLUTANTS ON THE SOURCE
As can be understood from the above-mentioned observation, deposits of pol-
lutants on the basin and, particularly on the sewer, are playing a considerably impor-
tant role. For this reason, a field survey of pollutants on the sources has been
carried out. Yabatagawa basin was also chosen for the field survey. The area is 5.4
km2 and is mainly residential. Its population is about 140,000 and population den-
sity is 260 person/ha. Detailed explanations on the survey are omitted here, and
only the results of the survey so far conducted are shown in Table 2.1. An example
of the survey is shown below for reference. In the case of survey on sewer manholes,
300 manholes were randomly sampled out of 6,000 manholes in the basin concerned
and the number of the existence of pollutant deposits was checked and the quantity
and quality of part of deposits were measured, thereby estimating the pollutant load
for 6,000 manholes. In the case of the street surface, pollutant load was estimated
from water sprinkling tests at only three places. From the results of the survey, it
was found that the load potential at this point of time was around 5 tons and the
deposits on the sewer accounted for the main part of the load potential, as shown in
Table 2.1.
Table 2.1 Sources of BOD Load in the Basin (Surveyed)
Location
Street Surface
Street Inlet
Sewer
Sewer Man Holes
House Inlet
Pervious Area
Total
Accumulated Load
(ton)
0.66
0.77
0.33
2.5
0.0
0.05
4.31
76
-------
2.4 SIMULATION OF BOD LOAD DISCHARGE
Various characteristics which were used for simulation are briefly described
here in the order of the equation of motion in items 2.4.1 and 2.4.2 and the equa-
tion of continuity for pollutants in item 2.4.3.
2.4.1 RELATIONSHIP BETWEEN DISCHARGE Q AND POLLUTANT LOAD
DISCHARGE Qs
It Was pointed out by the author earlier that the relation between discharge Q
and pollutant load discharge Qs can be expressed by Qs a Q for BOD if the loop is
ignored and the result is averaged, and Qs « Q2 * for SS, in which the loop charac-
teristics are weak owing to its properties. In dry weather, however, these relation-
ships were not strictly maintained and particularly at night, a rapid decrease of Qs
became remarkable. All the observed values for fiscal 1974 totaling 500 are plotted
in Fig. 2.8. Judging from this figure, it is clear that something like a concept of
critical tractive force in sediment load had better be introduced.
Fig. 2.8 BOD-Q (for 1974)
(Yabatagawa, Tokyo)
The relationship can be expressed by the following equation.
Qs = K'(Q-Qc) (1)
It is better not to think too seriously about what discharge should be taken as
Qc. Just consider as Qc the lowest hourly discharge at the location concerned at
dawn when the flow rate at each point in the basin drops and pollutants become
difficult to move.
* This expression agreed with the formula for suspended sediment discharge. For instance, refer
to "Applied Hydraulics" Vol. 2,1, p.27.
77
-------
2.4.2 INTRODUCTION OF BASIN RESIDUE LOAD (S)
As pointed out earlier in the item dealing with overflow quality characteristics
and taking into consideration the results of water sprinkling tests on the street sur-
face and sewer conducted by our section, a concept of basin residue load (S) is
introduced and Qs can be expressed as follows;
Qs = K"Sm (2)
The quantity S can be defined as the total load in the basin that can be dis-
charged out of the basin at each instant, and as can be seen from eq. (2), the smaller
S becomes, the smaller will be Qs. Particularly when m > 1, the decrease becomes
very rapid. Values K" and m will have to be obtained by simulation. Naturally this
value S should not widely differ from the results of the field survey of pollutant
sources mentioned earlier. From items 2.4.1 and 2.4.2, we can obtain an equation
of motion as shown below:
Qs - K Sm (Q - Qc) (3)
2.4.3 EQUATION OF CONTINUITY
Next, we need an equation of continuity, i.e., an equation which traces varia-
tion in time of the basin residue load.
This equation can be written as follows:
dS/dt = DWF -Qs (4)
and by approximation
AS = St+At - St = (DWF - Qs)At (4')
_ DWFt + At + DWFt Qs,t+At-Qs,t ^.,,
Z* £,
In eqs. (4) ~ (4"), DWF means dry weather BOD load discharge into the basin
(Input), and observed values of BOD load discharge in dry weather are substituted
for this supply because there is no other proper data of this kind.
2.4.4 INITIAL CONDITIONS (S0)
Eqs. (3) and (4) are already given. If Q is given from the observed value or
rainfall runoff analysis, and an initial basin residue load (S0) at the starting point of
calculation is given, calculations can be made successively.
The value S0 was obtained this time in the following way:
Namely, first, the values of exponent m and K with respect to pollutograph in
storm weather were obtained approximately, and these values were applied to the
data in dry weather (16 to 18 July, 1974). Then it was found that an equilibrium
was reached within about 1 day irrespective of the magnitude of S0 at initial time,
and an S-curve in dry weather was obtained. The values of constants were obtained
by a trial and error method and first exponent m was almost uniquely determined
from the load discharge characteristics in storm weather and then there was almost
no room for changing K. This was probably due to so many constraints such as
average load and amplitude in dry weather.
The result of simulation is shown in Fig. 2.9. In Fig. 2.9 the range of S spreads
from 4.5 tons to 5 tons. This figure unexpectedly shows near correspondence to the
result of the field survey of pollutant sources.
78
-------
Fig. 2.9 Simulation of Dry Weather BOD Load Discharge (Aug. 7 ~ 9,1974)
(Yabatagawa, Tokyo)
Discharge
Aug. 7-9, 1974
;200 - ^
/ (S0 = 4.95 ton)
"x Computed BOD
v-_^?
Observed BOD load
discharge
w
E 1
(Aug. 7)
(Aug. 8)
•5S
200
(S0 = 4.95 and 3.0 ton)
Q
O 100
CO
/ (S0 = 4.95
—L^z ~:
1
»— ^-- — ^*^ — ~~~
\
S0 =4.95 and 3.0 ton
i i i i i i i i i i j i i i i i i i i i i i i — i — i
, i i ,
16 18 20 22 24
(Aug. 8)
4 6 8 10 12 14 16 18 20
(Aug. 9)
If values of K and m are determined, there is another way to determine the
value of So which will agree with the observed value at the initial stage (sometimes
this method gave better agreement).
2.4.5 RESULTS OF SIMULATION
Figs. 2.10 ~ 2.14 show the results of simulation with m = 2.0, K = 11.43,
Qc = 0.87 m3/s (for fiscal 1974) and m = 2.0, K = 4.12, Qc = 0.6 m3 /s (for fiscal
1973) and using S at the same clock time in dry weather of Fig. 2.9 for So. Fig. 2.10
shows the results of continuous sampling for 10 days from 3rd to 12th July, 1974
and gives comparatively satisfactory results. It indicates good agreement for storm
weather and clearly expresses the decrease in BOD load discharge (recovery of de-
position) after rainfall. Values of observed discharge are omitted from Fig. 2.10 for
lock of space. Variation of S in time is also shown in Figs. 2.11 ~ 14, and rapid
decrease during storm and slow recovery can be seen.
79
-------
Fig. 2.10 Simulation Result of 10 Days' Observation
(Yabatagawa, Tokyo)
Observed
\7 18 19 20 22 02
11 13 15 17 19 20 21 22 0
80
-------
Fig. 2.11 Simulation Result (Yabatagawa, Tokyo)
Observed discharge
Dry weather flow
Observed concentration
Observed BOD load discharge
Computed BOD load discharge
Dry weather BOD load discharge
Computed basin residue load
12 13 14 IS 16 17 18 19 20 21 22 23 24 1 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19
81
-------
Fig. 2.12 Simulation Result (Yabatagawa, Tokyo)
. Observed discharge
Dry weather flow
BOD
(mg/S)
300
Observed concentration
Dry weather concentration
BOD
(g/s)
1600
Observed
Computed
Dry weather pattern
Computed basin residue load
S(ton)
15
82
-------
Fig. 2.13 Simulation Result (Yabatagawa, Tokyo)
00
Q(m3/s)
BOD
(g/s)
800 -
Aug. I. 1973
• Observed discharge
Dry weather flow
Observed BOD load discharge
Dry weather BOD load discharge
Computed BOD load discharge
S(ton)
Computed basin
residue load
14 15 16 17 18 19 20 21 22 23 24
—I 1 1—I 1—I—I 1 1 1 1—I 1 1_
2 3 4 5 6 7 8 9 10 11 12 13 14 15
-------
Fig. 2.14 Simulation Result (Yabatagawa, Tokyo)
Q
(m3/s)
6
4
2
BOD
(g/s)
800
600
400
200
S (ton)
8
6
4
Aug. 10, 1973
Observed discharge
Dry weather flow
Observed BOD load discharge
Dry weather BOD load discharge
— Computed BOD load discharge
Computed basin residue load
16
17
18
19
20
21
23
24
234 567
What poses a problem here is the difference in the values of constants between
the simulation for fiscal 1973 and that for fiscal 1974. A little examination on this
matter here will be justified. What should be first pointed out is that there is a dif-
ference between load discharge characteristics both in dry and storm weather for
fiscal 1973 and fiscal 1974. First for dry weather, the average load discharge in
fiscal 1973 is 149 g/s (BOD), whereas that in fiscal 1974 is 94 g/s (see Fig. 2.7), and
the reason for this is unknown. The petroleum crisis may be a partial cause, but is
considered insufficient to cause such a change. In addition, dry weather flow has
hardly changed. The method of chemical analysis does not offer any cause. Next
for storm weather, total load for one rainfall event for fiscal 1973, for instance, is 3
to 4 times as large as that for fiscal 1974. The cause for this is also not clearly
known. One of the conceivable causes is that pebbles which has caused deposits on
the sewer, were washed away by the great Hood close to the design discharge on
10th November, 1973 (Fig. 2.3) and, as a result, the basin residue load potential for
1974 seemed to be reduced. This interpretation is not unfounded, because the range
of S that was obtained by the simulation of the curve for dry weather in fiscal 1973
84
-------
was 6.0 to 9.7 tons and the results of simulation made by using this value of S show-
ed a good fit to observed values. It may be added here that the observed maximum
value of total load for one rainfall event was 8 tons (BOD5) on 15th July, 1967 and
on 10th November, 1973, and the field survey of pollutants source had been carried
out since the beginning of 1974.
2.5 PROBLEMS AND FUTURE PROSPECT
Although several problems are left unsolved, the simulation results are satis-
factory than were expected. Hereunder several problems are pointed out and future
prospect is reviewed for reference' sake.
2.5.1 PROBLEMS
a. The first tough problem is that it should be remembered that the simula-
tion is successful only for the Yabata basin. Further verification of the
model must be made by applying the simulation to the other basins. Since
the basin is located on a plateau, future investigation has to be made on the
sewered area with old pipelines and pumping stations. Such field investiga-
tion costs much and is very difficult work. However, if a field survey of
pollutant sources and two or three times of field sampling can accomplish
the work, this simulation model will be greatly beneficial.
b. The difference in survey results between fiscal 1973 and 1974 poses an-
other tough problem, which has to be checked in future. If deposition
characteristics of pollutants in the basin (K and exponent m for S) should
be assumed to change, the problem will become too difficult to be solved.
c. In this simulation, the component of BOD, that is, the existence of S-BOD
(Soluble BOD), for instance, has not been given much attention. But there
should be a model in which a part of such BOD does not contribute to the
deposition and flows down. The supply from the ground surface also has
to be included. It will be examined in the simulation of SS.
d. Regarding the problem that the substance of BOD may vary from dry
weather to storm weather, various checkings were effected by analysing the
deoxygenation coefficient, COD and TOC both for the dry and storm
weather, but there were hardly any differences between them.
2.5.2 FUTURE PROSPECT
a. In this method, simulation can be carried out if the characteristics of the
total basin load including S0 and data of storm water discharge are available.
The data of the discharge can be obtained from the rainfall data by using,
for instance, the modified RRL method, which has been verified at the
Yabata Basin and others. In such a case, simulation can be carried out with
S0, rainfall data and the formula of Qs.
b. In this sense, simulation of the prevention measures of combined sewer
overflow can be carried out, by using the rainfall data for about 10 years in
the past, if the formula of Qs and data concerning S0 are given. At present,
trial calculations are being made in respect to an increase in the dilution
ratio and the retarding basin, etc.
85
-------
c. Even if simulation for 10 years and consequently simulation for counter-
measures are carried out, it is a problem to determine what extent the
countermeasures should cut off the pollutants over-flow to. At present,
there are neither the standards nor the criteria to determine this matter. In
future, its effect upon receiving waters should be investigated.
ACKNOWLEDGEMENT
In 1967, the Sewerage section of P.W.R.I. started investigation at the Yabata
Basin. In 1969, the work was succeeded by the Urban River Section. Since then,
with the cooperation of many persons, a large number of results were obtained in
studies concerning urban runoff and pollutants discharge. Particularly, the author is
grateful to the personnels of the Planning Department of Sewerage works Bureau,
Tokyo Metropolitan Government for their generous financial assistance given to him
in carrying out the studies. Out of these officials, the deepest gratitude of the author
goes to Mr. Nagaharu Okuno, who is now with the Sewerage Works Agency, for his
kind assistance and valuable advice. This paper is dedicated to him. Beside the
above, the author would like to take this opportunity of expressing his deep appre-
ciation to all the stuff of the section who gave their assistance and advice to him in
carrying out the studies.
APPENDIX
After this paper was completed, the same simulation procedure described above
was applied to the other two catchment area. (A and B cities) Fig. 2.15 ~ 2.24
show results of the study.
Fig. 2.15 Simulation Result (Dry Weather)
A City, Oct. 23, 1975
Computed value
Observed value
100 -
'3 '4 " '« " 18 .9 20
20 2 22 23 24 , 2 , 4 V
6789
86
-------
Fig. 2.16 Simulation Result
A City, Aug. 6,1975
Fig. 2.17 Simulation Result
A City, July 7,1975
14-00 15-00 I600 17.00 IB 00 ><> 00 20:00
10-00 I LOO 12.00 13:00 14:00 15:00
(g/sec)
700
400
Fig. 2.18 Simulation Result
A City, Feb. 5, 1976
13
Time
87
-------
Fig. 2.19 Simulation Result
B City, July 19, 1976
BOD
loading
(g/sec
I 50
I 00
C M N
o Observed value
Computed value 900 2 !
Computed value 100 2 1
13 00
14:00
15:00
Time
-------
Fig. 2.20 Simulation Result
B City, Aug. 2,1976
BOD
(g/s)
300
250
• • Observed value
Computed value 900
Computed value 100
200
150
100 _
50 -
M N
15:00
16:00
Time
89
-------
ID
o
BOD
loading
(g/sec)
300
200
100
f
b-o-ooo
Fig. 2.21 Simulation Result
B City, Aug. 26,1976
M N
Observed value
Computed value 900
Computed value 100
0.53
1.44
10:00
11:00
12:00
13:00
14:00
15:00
-------
Fig. 2.22 Simulation Result
B City, Sept. 18,1975
BOD
(list
100-
• . Observed value
Computed value 900
Computed value 100
M N
Fig. 2.23 Simulation Result
B City, Sept. 8,197S
C M
BOD
(I/I)
• • Observed value
Computed value 900
Computed value 100
N
1
1
Fig. 2.24 Simulation Result
B City, Oct. 7,1975
BOD
Ig/s)
. . Observed value
Computed value 900
Computed value 100
M N
91
-------
FIFTH US/JAPAN CONFERENCE
ON
SEWAGE TREATMENT TECHNOLOGY
PAPER NO, 3
STUDIES ON SLUDGE TREATMENT
APRIL 26-28, 1977
TOKYO, JAPAN
MINISTRY OF CONSTRUCTION
JAPANESE GOVERNMENT
93
-------
STUDIES ON SLUDGE TREATMENT
1. PERFORMANCE AND EVALUATION OF MECHANICAL SLUDGE
DEWATERING FACILITIES IN YOKOHAMA CITY 95
S. Miyakoshi, Yokohama City
2. SLUDGE CONDITIONING BY USING HYDROGEN PEROXIDE 122
K. Tani, Osaka City
3. SURVEY OF ECONOMICAL AND TECHNICAL PERFORMANCE
FOR EMISSION CONTROL EQUIPMENT INSTALLED WITH
SLUDGE INCINERATOR 137
Dr. A. Sugiki, Japan Sewage Works Agency
4. STUDIES ON SEWAGE SLUDGE PYROLYSIS .163
Dr. M. Kashiwaya, PWRI, Ministry of Construction
94
-------
CHAPTER 1
PERFORMANCE AND EVALUATION OF
MECHANICAL SLUDGE DEWATERING FACILITIES
IN YOKOHAMA CITY
1.1 Present Status of the Mechanical Sludge-Dewatering Facilities 96
1.1.1 Explanation of the Facilities 96
1.1.2 The Reason of Selecting the Machines 101
1.1.3 Maintenance 101
1.1.4 The Results of Operation 103
1.1.5 Operation and Maintenance Cost 107
1.2 The Relation between the Feed Sludge and the Dewatering Efficiency .. . 107
1.2.1 TS and VTS 108
1.2.2 Dewatering Rate and VTS 108
1.2.3 Dosing Rate and VTS 108
1.2.4 Water Content and VTS 109
1.3 Evaluation of the Dewatering Machines 113
1.3.1 The Range of the Comparison 113
1.3.2 The Method of Determining the Capacity of the
Dewatering Machines 113
1.3.3 Evaluation 117
95
-------
PERFORMANCE AND EVALUATION OF
MECHANICAL SLUDGE DEWATERING FACILITIES
IN YOKOHAMA CITY
According to the sewerage plan of Yokohama City, the total city area will be
divided into nine treatment districts wherein ten sewage treatment plants are to be
erected.
Five treatment plants are already in operation, where the secondary treatment
by the activated sludge process is carried out.
As to the sludge treatment, thickened sludge (mixture of raw primary sludge
and waste activated sludge) is processed by anaerobic digestion followed by dewater-
ing in two treatment plants, by wet air oxidation followed by dewatering in a treat-
ment plant and by dewatering of thickened sludge in other plants.
The amount of the sludge cake produced in five treatment plants is about
9,700t per annum as solid (48,150t as wet cake), 95% of which (9,160t) is disposed
for land fill in municipal refuse disposal area as sludge cake and the remaining 540t
is used for reclamation to agricultural land and green field as sludge cake or after
mechanical sludge drying.
1.1 PRESENT STATUS OF THE MECHANICAL SLUDGE-DEWATERING
FACILITIES
1.1.1 EXPLANATION OF THE FACILITIES
In city's dewatering facilities are installed belt-discharge vacuum filters (which
will be referred to as BVF hereafter), pressure filters (an HPF refers to the horizon-
tal type and a VPF the vertical type hereafter. A PF includes both of them) and
centrifuges (which will be denoted an SD hereafter) as the flow sheets of sludge
treatment in respective treatment plants in Figs. 1.1 ^4 show. In BVFs and PFs are
installed inorganic coagulant (ferric chloride, carbide slurry) dosing devices shown
in Fig. 1.5 and in SDs polymeric coagulant dosing devices shown in Fig. 1.6. The
types of auxiliary devices are markedly different depending upon the types of the
machines as shown in flow sheets in Figs. 1.7 ^ 10 and a list of facilities in Table 1.1.
The process of installation of the dewatering facilities and the present treatment
capacities in respective treatment plants are shown in Fig. 1.11.
96
-------
Fig. 1.1 Flowsheet of Sludge Treatment in Chubu S.T.P.
Sludge \ThickenedSluclge
Thickening ' =-•
Waste Activated \ Tank
Sludge
Elutriated Sludpe
Inorganic
Coagulant
Dosing Device
Dosed Sludge
Vacuum
Filtration
Equipment
Fig. 1.2 Flowsheet of Sludge Treatment in Nambu S.T.P.
— -=•- to Sludge D'rii
Inorganic
Dosing Device
Dosed
Sludge
Vacuum
Filtration
Equipment
Sludge
Cake
i Sludge Dm
Fig. 1.3 Flowsheet of Sludge Treatment in HOKUBU S.T.P.
Raw Primary
Sludge / Slud|
Thickei
Waste Activated \ Tank
Sludge
L
Fig. 1.4 Flowsheet of Sludge Treatment in the Second Totsuka S.T.P.
Raw Primary .^
Sludge / Sludge \s|udge 7 Sludge
-i »-( Thickening W Storage
Waste Activated \ Tank / \ Tank
Sludge
Dosing Device
Dosed
Sludge
Virtical Type
Pressure
Filtration
Equipment
Sludge
Cake
=
97
-------
Fig. 1.5 Flowchart of Inorganic Coagulant Doting Device
Fig. 1.6 Flowsheet of Polymeric Coagulant Doting Device
Carb
Star
•H
de Slurry
»ge Tank
tl
Chloride
Storage
Tank
Q
q
Carbide 1
Slurry
Tank
fe
LL&J
Carbide Slurry
Feed Pump
Ferric Chlonde
• Resolution
• Tank
1— £P— '
4-
I
Floculation Tank
*1 Carbide slurry, which is waste acetylene
sludge, contains 2(H 25% of slaked lime.
•2Fernc Chloride is added as a 37.3%
solution.
- •
[*J
Constant Feeder
-I- Resolution Tank
I [_ to Centrifugal
*|__ Jfc Separation Equipment
A ents
Service Tank
Fig. 1.7 Flowsheet of Vacuum Filtration Equipment
Treated Sewagef
from Flocculation Tank
Fig. 1.8 Flovnheat of Centrifugal Sflparation Equiprnfirrt
H"PP"
Treated Sewage
Cleaning Water
Coagulant Feed Pump
from Agents Service Tank f-~^—^
from Sludge Service Tank
Feei Pump
to Hopper
Fig. 1.9 Flowsheet of Horizontal Type Pressure Filtration Equipment
Oil Pump Unit
ized
Feed Blow
Back Blowl
L i c
III
HPF
III
I
1
Slud
V
r
geCake
J
- to Hopper
f|8 , 10
Irom Floccu a[ion
Compressor
Treated Sewage
Treated Sewage
of virtical Type Pretsure Filtration Equipment
Filtration Pump
Hopper
98
-------
Fig. 1.11 Time Course of Installation of the Dewatering Machines in
Respective Treatment Plants
\FV
S.TPS
3
£>
3
s:
t_>
3
.O
E
ca
z
3
£3
3
2t
0
X
'M
8l
iU O
WH
Kohoki
'62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77
1
1
SVF [''BVF '•'•'•'•'•'•'•'•'•••'••••••••••••••.•.•.•.'.•.•.•.•.•.•.•.•.•.•.•.•.•. '
I'BVF ••'•'•'•'•'•'•'•'•'•'••••••••••.'.•.•.•.•.•.•.•.•.•.•.•.•.•.•.•. '
I'BVF'.'.'-V. '.•.'.•.•.•.•.•.•.•.•.•.•.•.•.•.•.•.•.•.•.•.•.•.•
1
1
. -BVF-. •.•.•.•.•.•.•.•.•.•.•.•.-.•.•.•.•.•.•.•.•.•.•.•.•.•.•.•. •
_. BVF-. •.-.•. •.•.•!•!•!•!-. •!•'•'•!•'•'•'•'•'•'•.•.•.•.•.•.•. •!•
•!BVF>;-;-;-;-;-;-;-;-;-. •.•;•;•;•;•;•.
.-.so.'. •.•.•••••••.•••.•.•.•
•• 'SD.'. •••.•••. ••••••
-.'•so ;•;•;•;•;•;•;•;•;
:-'HPF-'-'-'-'-'-'-'-'-'-'-'. •••.•.•••••••••••••••. •••••••
.'.HPF'. •.•.•.•.•.•.•.•.•.•.•.•.•.•.•.•.-.•.•.•.•.•.•.•.•.
•.i#f ••••••••••.•.•.•.•.•••••••••••.•.•
.'HPF-'.'. •.'.'.
.'HPF.'. •.'.'.',
1
1
I1 V ft, -,'.'.'.'.'.'.'.*
1 L ' VPF. •^•J'. •.'.'. •.•-•!
LYf£i
! VPF'
1 j — r — «
[VPF
- 0
<;
- 0
- 5
-10
-15
-20
-25
30
-
- 0
- 5
-10
n
- 5
* A scale on the right represents the treatment capacity of ton of the treated sludge dry solids per day.
SDs are assumed to run 24 hours a day and others 7 hours a day. The working ratio is assumed to be 0.8.
The treatment capacity per hour is taken after the previous results of the city.
99
-------
Table 1.1 The List of Dewatering Facilities in Respective Treatment Plants
o
o
f;
I
£
1
£,
I
" -
t " °
S5
\
5"
•< — x --<
S (, J
I |*3
a = »-
1 |l
(,'hubu Sowagp Tipulrnenl Plant
Ty,ie Bell -Discharge
Vacuum P. 1 ler
/)
J.r> m(V)
Ki.lai iniiBt 0. li - 0.'> r|Kii
Filter Cloth Polypropylene
Numbrr ) uni ! s
(DevmerinR Equipment)
Pi 1 I rale Hump 3
The- Other Pumps 6
AJ T Compressor
AgHiil.ir 4
(DosinK Devic e)
Slurrv
Agilalcr lor Ferrir ^
Chloride
ftm.|i Icr PVi-nrk 4
(Jon Tank
Cam PI S\ steTn)
Cake Hopper ^
Tola] 37 unilf.
Elul nated
pa
P* .\
persons for ) un i 1 s
34. K m x 14 m) 487-2 m2
Nambu Se.agP 1
Vacuum Pi I 1 er
3.- m(W)
Hotal lonal 0. U 0. 1 rpm
Filter Cloih Pol v|.r(.|.v[ene
NumbeJ' 1 uni L.s
(Dewater,nK Equipment)
FiJ Irate Pumjj
The Other PumFj--- 8
Compressor 2
(Dosinfi Dp\ ire)
Slurrv
Chi., ride
Pump Cur Ferric 3
1 ion Tank
(Carrier System)
Cnnvever 10
Cake Hopper
Tuial 73 units
Elul nated
pa
Pa .
t persons r«.r 1 units
27.0 m X IT m) 405 m^
Fl.u Hale
Number 4 uni Is
(Dewalerjnn Equipment)
Coagulant Pped Pump 4
The 01 her Piimps 2
Agitalor
(Dosing Devire)
Coagulant Hopper
Coagulant Constant
Polymenc 1
Coagulant Constant
Feeder
(Carrier System)
C»n\«»pr 7
Cake Hopper 4
Tntal 32 units
Digested
I»
pa
! person for 4 units
(27.0 m x 11,0 m) 40S m2
Type Horizontal Type
Chamber (1 m(L) x
1 m(tf)>
Number b uni ts
(Devatering Equipment)
The Other Pumps 4
Compressor 4
Oil Pump Unit 3
Agitator 6
(Dosing Device)"
Slurry
Slurry
Pump for Ferric I unit
Chloride
(ion Tank
(Carrier System)
Con\e.ver 8
Cake Hopper 2
Total 43 units
{A*M Thi.kened
pa ,
pa
Oxidation) ing of Thickened
Sludge
6 units 6 units
(28 m x 13.6) 38O.8 m2
Type Vertical Type
Pressure Filter
Chamber (0-9 m(L) x
i.75 m(W)>
(to be 6)
iDevatenng Equipment)
The Other Pumps 8
Compressor 2
Oil Pump Unit 1 unit
(Dosing Device)
Slurry
Slurry
A«iLBtor for Ferric 2
Chloride
Chloride
(Carrier System)
Conveyer 5
Cake Hopper 4
Total 34 units
Thickened
pa y
2 persons for 2 units
(15 m x 25 m) 371 m*
-------
1.1.2 THE REASON OF SELECTING THE MACHINES
a. Chubu Sewage Treatment Plant
Chubu Sewage Treatment Plant, the first treatment plant erected in Yokohama
City, has been in operation since 1962. In selecting the dewatering facilities, scraper-
discharge vacuum filters whose positive achievement was known then were adopted.
Later, the machines were changed to BVFs in 1965 because the achievement of
the BVF with a larger treating capacity than the scraper-discharge vacuum filter was
known.
b. Nambu Sewage Treatment Plant
BVFs were installed as the dewatering machines of the Nambu Sewage Treat-
ment Plant in 1967 after the experience. in the Chubu Sewage Treatment Plant.
However, as the ratio between the night soil and the sewage sludge decreased later,
the expected capacity could not be achieved and the enlargement of the facilities
became necessary. After many considerations, SDs with improved efficiency by
structural modifications and the use of polymeric coagulant were adopted in 1973.
These machines fulfilled the requirements of limited installation space and continu-
ous operation with infrequent inspection.
c. Hokubu Sewage Treatment Plant
For dewatering of the sludge after wet air oxidation obtained in Hokubu
Sewage Treatment plant, BVFs and HPFs were compared and HPFs which yield
cakes with lower water content were installed in 1968.
d. Second Totsuka Sewage Treatment Plant
PFs were selected as the dewatering machines of Totsuka Sewage Treatment
Plant, which was expected to yield cakes with lower water content so that the dis-
posal by land fill is easy and the disposal after incineration expected in the future is
advantageous. VPFs with a greater filtration rate and a smaller installation space
than HPFs were installed and have been in operation since 1974.
1.1.3 MAINTENANCE
a. Characteristics of Maintenance
Various running characteristics, problems and periodical inspections etc. are
shown in Table 1.2.
b. Main Modifications
Various modifications have been carried out after our operating experience,
some examples of which will be described below.
-BVF
- To prevent clogging of the filter cloth and to improve the efficiency of the
dewatering machines, automatic filter cloth washing machines which utilize water at
high pressure (rapidly filtered water after secondary treatment) were installed.
Washing is carried out automatically for about 30 minutes after the dewatering
operation is over by spraying water at high pressure evenly over the filter cloth as
the washing nozzle reciprocates horizontally while the drum rotates. As a result of
this modification, the dewatering operation could be prolonged by about an hour a
day.
101
-------
Table 1.2 Characteristics of Maintenance
o
t-o
^^^"Types of
^^ Machines
Items ^^^
Operating Characteristics
Details of the
Periodical
Inspection
Maintenance
£ *-
•J: M> p c
£ -S £ 1
* c c
D
BVF
(1) Because the dewatering is conducted by filtering by vacuum,
there is a limit to the water content of the sludge cake.
(2) Not suited for dilute sludge. Empirically, when TS concentra-
tion is less than 3%, the cake layer is not formed, the filter
cloth cloggs quickly, the cake barely comes off and hence
dewatering is impossible.
(3) If the disposal of the cake by land fill is planned or if con-
tinuously stable cake is needed, the feed sludge, with more
than 4% of TS is necessary. (Empirical rule)
(4) To maintain the filtering capacity, large amount of the filter
cloth and the washing water is necessary. The filter cloth
must be washed with acid for regeneration.
(5) Carbide slurry used as a dewatering adjutant adheres to the
vacuum tube in the drum as hard scales lowering the filtra-
tion rate and hence must be cleaned periodically
(6) The filter cloth tends to form wrinkling which influences the
filtration rate.
(7) Because the open area is large, some measure must be taken
to prevent odor.
[1) No legal obligation of inspection.
(2) Auxiliary devices such as a vacuum pump or a filtrate pump
are important in dewatering and require rigorous periodical
repair.
'3) Machines with sliding parts such as a cake discharge roller, a
high flow valve and a compressor must be periodically
inspected.
(4) The filter cloth must be washed with acid for regeneration.
(1) Duration of the filter cloth must be judged and the filter
cloth must be exchanged.
;2) Coming off of the cake, winding of the filter cloth etc. must
be inspected. If necessary the revolving rate of the drum and
the dosing rate must be controlled.
[3) There are many kinds of auxiliary devices such as a vacuum
pump, and their maintenance is indispensable for stable and
effective dewatering.
(1) While washing the filter cloth, the worker might inhale the
volatile component of acid.
(2) Dewatering of the thickened sludge causes bad odor.
PF
(1) Dewatering i< conducted by pressing and squeezing, and
hence the water content of the sludge cake can be low.
(Sludge cake with the lower water content can be obtained
than any other types of the machines.)
(2) Since the machine is operated batchwise, when the initial TS
concentration is higher, the filtration rate is greater and more
stable.
(3) Not suited for dilute sludge. Dewatering is not impossible but
the cycle time must be considerably prolonged, the dosing
rate must be extremely large, and the filtration rate is
expected to become very low.
(4) The cycle time can be controlled but it will not improve the
filtration rate to any great extent,
(5) To maintain the filtering efficiency, filter cloth washing
water at high pressure is necessary. The filter cloth must be
washed with acid for regeneration.
(6) If the dewatering process is carried out while the cake is
adhered to the frame of the filter cloth, it sometimes leaks
between the filter cloth and filter plate.
(1) No legal obligation of inspection.
(2) The filter plate m'oving mechanism must be periodically
repaired.
Adjustment and renewal of parts of the oil cylinder or the
opening and closing mechanism of the filter plate are
necessary.
(3) Machines with sliding parts must be periodically inspected.
(4) Same as BVF (4)
(1) Same as BVF (1)
(2) The wrinkling of the filter cloth, the leakage between the
filter doth and the filter plate, coming off of the cake and so
forth must be watched. Cycle time must be adjusted.
(3) Careful maintenance of the auxiliary devices is indispensable
foi stable and effective dewatering.
Same as BVF
SD
1) Dewatering mechanism is the forced consolidation and pre-
cipitation. Therefore, it is possible to dewater at a low con-
centration of TS. If one may ignore the recovery ratio of
solids to some extent, the machine may be operated without
dosing.
(2) If a proper coagulant is selected, the machine may be operat-
ed at a low dosing rate. The water content of the cake is
influenced by the amount of VTS.
(3) The feeding rate of dry solids is limited by the strength of the
gears. Hence, if the sludge is very thick, the flow rate must be
controlled.
(4) Properties of the sludge cake are not suited for disposal by
land fill. But the water content in the sludge cake is small in
comparison with BVFs. Stable production of the cake is not
limited by the concentration of the feed sludge in contrast
to other types of machines.
(5) Feed sludge rich in sand wears the screw rotor and the outer
drum quickly. Hence the sand must be fully removed.
(6) Rotation at high speed causes vibration and noise when the
machine is in operation.
(7) Because of the high-speed rotation, screw rotor, outer drum
and the outlet tend to wear quickly and must be periodically
repaired.
(8) The separated liquid foam readily sometimes making drainage
difficult.
(1) Periodical and voluntary inspection of a centrifuge with a
revolving part at high speed is imposed by the Safety and
Hygiene in Labor Act.
(2) Because of the high-speed rotation, planet gears and bearings
must be periodically inspected.
(3) Wear of the parts which slide or collide with the sludge such
as screw rotor and the outer drum must be repaired.
(1) The separated liquid, the state of the cake and driving force
of the rotor must watched. The dosing rate and the feeding
rate must be controlled.
(1) Noise and vibration during operation are large.
-------
- To better the coming off of the cakes, flapper rollers were installed. By this
modification, TS concentration limit at which the coming off of the cakes becomes
bad was improved to 3% from 3.5%.
-SD
— Because the inner drum screw and solids discharge outlets wore out rapidly,
the padding material was changed to a wear-proof one. By this modification, the life
time was lengthened from 1,800 hours to over 3,000 hours. For this reason and for
having changed the rate of rotation from 3,400 rpm to 2,400 rpm, the machines
have already been operating continuously over 4,000 hours.
-HPF
— When slack filter cloth is introduced into plate closing process, wrinkling of
the filter cloth arises which results in breakage. To prevent this, a weight (a round
bar of vinyl chloride) was placed at the lower end of the filter cloth, by which
modification the wrinkling arose no more.
1.1.4 THE RESULTS OF OPERATION
The results of operation in respective treatment plants in 1975 are shown in
Tables 1.3 ^ 6. Because the SDs in Nambu Sewage Treatment Plant were modified,
the results after June, 1976 are shown (Table 1.4).
In Table 1.7 operating states of respective dewatering machines are compared.
The dewatering rates of aH of the dewatering machines were lower than was initially
expected partially in connection with the quality of the feed sludge.
The difference between the standard operation and maintenance cost and the
actual one arose mainly due to the difference in the number of the operating
personnel.
Fig. 1.12 Automatic Filter Cloth
Washing Device by High-
Pressure Water
Fig. 1.13 Cake Flapper Device
Nozzle Header
(Nozzle Flat Type, Spray Angle 20°)
Discharge Rollei
103
-------
Table 1.3 The Results of Operation at Chubu S.T.P.
(BVF)
Month, Year
Apr., 1975
May,
Jim. ,
Jul. ,
Aug.,
Sept. ,
Oct.,
Nov.,
Dec. ,
Jan., 1976
Feb.,
Mar.,
Average
Feed Sludge
(Elutriated Sludge)
TS(%)
3.8
3.0
3.9
4.6
4.0
4.1
4.1
4.9
5.8
5.0
4.0
4.3
4.3
VTS(Z)
49
49
46
44
47
48
46
48
38
43
48
49
46
Dosing Rates (%)
Carbide
Slurry
32.9
50.8
54.0
42.3
44.2
47.3
40.9
34.1
27.9
31.2
44.0
37.1
40.6
Ferric
Chloride
5.9
10.5
11.0
8.2
8.2
8.3
7.9
6.9
5.1
6.4
8.9
7.9
7.9
Sludge Cake
IS (%)
22
21
22
24
25
22
23
26
24
24
24
23
23
»2
Filtration
Rate
CKe/mZ-h)
13.0
9.4
9.9
12.9
12.0
11.5
12.8
15.6
19.2
19.9
13.9
15.6
13.9
Average
Operating Time
(h/unit-day)
3.0
3.5
3.4
4.3
3.7
3.0
4.9
3.3
3.8
3.7
3.7
2.8
3.5
* 1 The dosing rates are the weight ratios of slaked lime and ferric chloride to the amount of solid in the sludge.
(Same for all of the treatment plants.)
*2 The filtration rate is given on the basis of the amount of solids in sludge cake excluding the coagulant.
("Same for all of the treatment plants.)
*3 The average operating time is the total operating time divided by the number of machines operated.
(Same for all of the treatment plants.)
Table 1.4 The Results of Operation at Nambu S.T.P.
(BVF)
Month, Year
Jim., 1976
Jul.,
Aug.,
Sept. ,
Oct. ,
Nov. ,
Average
Feed Sludge
(Elutriated Sludge)
TS(Z)
3.4
3.8
-J.b
3.7
4.6
4.5
3.9
VTS(Z)
45
41
40
42
41
45
42
Dosing Rates(%)
Carbide
Slurry
39
33
26
28
25
24
29
Ferric
Chloride
7.8
6.7
6.4
6.6
5.2
5.5
6.4
Sludge Cake
TS «)
22
23
23
22
25
22
23
Filtration
Rate
(Kg/mZ-h)
10.0
8.8
8.2
10.4
11.5
9.8
9.8
Average
Operating Time
(h/unit.day)
6.0
5.7
6.3
5.8
5.6
3.4
5.5
Month, Year
Jun., 1976
Jul. ,
Aug. ,
Sept. ,
Oct. ,
Nov .
Average
Feed Sludge
(Digested Sludge)
TS(Z)
3.2
3.6
3.8
3.5
J .4
3.1
3.4
VTS(2)
44
43
43
43
44
47
44
(SD)
Dosing Ratea(Z)
Polymeric
Coaeulant
0.86
0.83
0.78
0.78
0.78
0.74
0.80
Sludge Cake
TS (I)
25
26
25
26
26
23
25
Feeding
Rate of *
Dry Solids
284
278
291
277
246
260
273
Average
Operating Time
(h/unit-day)
20.1
17.3
13.2
15.0
16.0
11.1
15.5
104
-------
Table 1.5 The Results of Operation at HokubuS.T.P.
(HPF)
Month Day,
Year
May 2,
1975
Jul.25,
Jul . 31 ,
Oct. 22,
Oct. 23,
Mar . 5 ,
1976
Mar. 9,
Mar. 16,
Mar. 26,
Average
Feed Sludge
(Thickened Sludge)
TSU)
9.2
7.3
5.6
7.9
7.9
10.2
9.8
10.4
8.5
VTS(%)
38
36
36
37
Dosing Rates (%)
Carbide
Slurry
38
54
34
34
46
59
59
76
65
52
Ferric
Chloride
5.0
3.6
4.0
2.4
2.5
5.0
6.0
6.0
5.0
4.4
Sludge Cake
TS (%)
41
36
37
42
40
44
41
44
37
40
Filtration
Rate
(Kg/m2-h)
3.5
2.8
2.7
4.1
3.9
3.5
3.0
3.0
2.8
3.3
Average
Operating Time
(h/unit-day)
5.3
3.6
3.5
3.5
4.0
Table 1.6 The Results of Operation at the Second Totsuka S.T.P.
(VPF)
Month, Year
Apr., 1975
May,
Jun. ,
Jul.,
Aug. ,
Sept. ,
Oct. ,
Nov. ,
Dec. ,
Jan., 1976
Feb.,
Mar.,
Average
Feed Sludge
(Thickened Sludge)
TS(%)
6.0
6.2
7.3
7.3
5.6
5.0
7.9
5.8
4.5
3.0
3.5
4.6
5.5
VTS(%)
39
40
37
34
40
45
34
43
53
61
62
58
46
Dosing Rates
Carbide
Slurry
53
39
51
37
39
39
38
42
51
56
59
56
47
Ferric
Chloride
8.9
9.0
7.7
7.8
7.3
7.3
7.2
7.9
12.0
13.0
11.0
11.0
9.1
Sludge Cake
TS (%)
43
38
40
44
45
44
44
42
35
31
31
34
39
Filtration
Rate
(Kg/m2.h)
8.0
7.5
8.0
9.7
7.8
6.7
11.0
7.4
6.1
4.9
3.7
4.6
7.1
Average
Operating Time
(h/unit-day)
8.3*1
7.1
6.9
6.9
7.0
6.6
6.6
6.7
6.5
10. 6*2
15. 6*2
7.2
8.0
* 1 In April, 1975, the dewatering machines were operated for 10 hours a day.
*2 From Jan. 28 to Feb. 21, 1976, the machines were operated for 24 hours a day.
105
-------
Table 1.7 Comparison of Respective Dewatering Machines
^^Types~
Items
Feed Sludge
(annual averages)
Dosing Rates
Sludge Cake
(annual average)
(kg/mZ-h)
Actual Working Times
of
Dewatering Machines
(h/unit-day)
Oper tors
(per ons/unit)
Oper tion and
Main enance Costs
per on of Feed Dry
Solids (S/ton)
S.I. P.
-.JJachines
Kinds
TS(2)
VTS(%)
Carbide
SlurryU)
Ferric
Chloride(%)
TS«)
Rated
Actual
Actual
Standard
Actual
Standard
Actual
Standard
Chubu
BVF
Elutriated Sludge
$.1
48.0
40.6
7.9
23.0
25.0
13.9
3.5
3.0
1.3
0.8
170.14
148.61
Ms
BVF
Elutriated Sludge
3.9
42.0
29.0
6.8
23.0
25.0
9.8
5.5
5.6
0.8
0.8
138.42
138.59
»bu
SD
Digested Sludge
3.4
44.0
• Polymeric
Coagulant
0.8
25.0
The feeding rate of
Dry Solids
400 kg/hr
The feeding rate of
Dry Solids
273 kg/hr
15.5
19.2
0.25
0.2
104.73
104.04
Hokubu
HPF
Thickened Sludge
8.4
37.0
51.7
4.4
40.2
5.5
3.3
4.0
5.6
0.5
0.4
106.45
99.97
Second Totsuka
VPF
Thickened Sludge
5.5
45.5
46.6
9.1
39.2
15.0
7.1
8.0
5.6
1.0
0.4
133.39
119.01
These are the estimated standard valui
machines.
lues of the working hour and the operating personnel for respective
The standard cost was calculated on this basis
Table 1.8 Details of the Standard Operation and Maintenance Cost per
Ton of Feed Dry Solids
^^iL
Details \
Coagulant
Cost
Personnel
Cose
Electric
Carriage
Cost
Disposal
Cost
Repair
Cost
Grand
Total
BVF
(Chubu)
Feed Dry Solids
6.33t/day
Number 3 units
Costs
Sums(S)
14. 14*1
19.97*:
12.84
3.87
L7.94
75.37
2.48
148.61
Percentage
(10)
(13)
23
9
2
13
51
2
100
BVF
(Nambu)
Feed Dry Solids
9. 30t/day
Number 5 units
Costs
Sums(S)
10.10
17.17
14.58
3.67
18.21
68.83
6.03
138.59
Percentage
(7)
(12)
19
11
3
13
50
4
100
SD
Feed Dry Solids
26. lit/day
Number 4 units
Costs
Sums(S)
"3
34.67
1.05
6.08
12.44
47.02
2.78
104.04
Percentage
33
1
6
12
45
2
100
HPF
Feed Dry Solids
9.23t/day
Number b units
Costs
Sums(S)
17.97
11.11
0.81
1.46
12.04
45.50
3.08
99.97
Percentage
(18)
(11)
29
9
1
12
46
3
100
VPF
Feed Dry Solids
1.99t/day
Number 2 units
Costs
Sums (5)
16.02
22.68
13.62
6.57
12.25
46.32
1.55
119.01
Percentage
(14)
(19)
33
11
6
10
39
1
100
* 1 Carbide Slurry
'2 Ferric Chloride *3 Polymeric Coagulant
106
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1.1.5 OPERATION AND MAINTENANCE COST
Details of the standard operation and maintenance cost are shown in Table 1.8.
a. The BVF is the most expensive and the HPF the least expensive. This is
considered to be related to the fact that the feed sludge to the BVF (TS 4.3%, VTS
48%) is the most difficult to dewater while the feed sludge to the HPF (TS 8.4%,
VTS 37%) is easy to dewater.
b. The cost of disposal occupies a large portion of the cost, between 39% and
51%, in all of the machines. Then follows the coagulant cost which is between 23%
and 33%. The fact indicates that, to lessen the dewatering cost, a machine with a
smaller amount of cake produced, i.e., with lower water content of the sludge
cake, and a lower dosing rate should be selected.
1.2 THE RELATION BETWEEN THE FEED SLUDGE AND THE
DEWATERING EFFICIENCY
The major problem in dewatering treatment of the sludge is the fluctuation in
quantity and quality of the feed sludge. The fluctuation in quantity can be coped
with by storage and proper selection of the operating hours.
The fluctuation in quality of the sludge causes the fluctuation in the water
content of the sludge cake resulting in poor coming off of the cake and extreme
diffuculty of the dewatering operation.
Sludge treatment facilities have hitherto been designed by application of the
standard dosing rate and filtration rate expecting sludge of the standard quality.
Therefore, when the dewatering of the sludge becomes poor, the dosing rate must be
increased and the operating time must be temporarily prolonged. Such changes not
only cause problems in sludge treatment and personnel management, but also induce
the suppression of the withdrawal of the sludge and the increase in the amount of
the circulating sludge, which together cause serious problems in the quality of the
sewage treatment plant effluent.
Therefore in design, operation management and evaluation of the dewatering
machines, it is important to know the characteristics of the machines, such as the
quality of the product of the machines, the rate of production and the controlling
factors, in response to the fluctuation in the quality of the feed sludge.
The dewatering process has a three dimensional structure with variables, the
quality of the feed sludge (x), water content of the sludge cake (y) and the dewater-
ing rate (z) and the controlling factor (p) as the parameter. However, it is not easy to
solve it. Therefore, as an approximation for practical purposes, the relations, y=f(x),
z=f(x) and p=f(x) with the assumptions that x is a given variable and that two
excluded variables are within appropriate ranges, provide enough information to
decide how to cope with the situation in the plant and to reveal the characteristics
of the dewatering machines.
Among many factors which may be taken to represent x,y,z and p, our operat-
ing experience up to now suggests to select VTS for x, dosing rate for p, water
content of the sludge cake for y and the filtration rate on the basis of the treated
solid for z. Taking such factors as the variables, the aforementioned relations will be
as follows.
107
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1.2.1 TS AND VTS
TS of the feed sludge has hitherto been counted among the factors which
determine the dewatering efficiency of the dewatering machines including the filtra-
tion rate. It is also our experience that the dewatering efficiency changes depending
upon the TS. But when we encounter seasonal difficulty in dewatering of the
sludges, TS decreases but at the same time VTS increases. The phenomenon is
thought to arise from the facts that the feed sludge has been thickened and separat-
ed in a so-called gravity thickener and that the components of VTS are inhibitory
factors of thickening with high viscosity and strong affinity to water. Therefore, as a
parameter to represent the properties of the sludge VTS is preferred.
The relation between TS and VTS is shown in Fig. 1.14.
The seasonal fluctuation in the amount of VTS is shown in Fig. 1.15.
The amount of VTS fluctuates seasonally in any of the municipal treatment
plants. When the VTS level is high, dewatering is difficult. Also, the longer the plant
has been in operation, the higher the VTS level is.
1.2.2 DEWATERING RATE AND VTS
The relation between the filtration rate and VTS in the BVF and the VPF is
shown in Fig. 1.16. The straight line in the figure is a regression line.
In the information obtained from the BVF, the range of the VTS level of the
elutriated sludge is narrow and scattering is large. Therefore, the correlation between
VTS and the filtration rate is more marked in the VPF than in the BVF.
Some of the characteristics of the machines found in this figure are as follows.
a. Because BVFs are run continuously, the filtration rate of the BVF is greater
than that of the VPF, but the VTS level of the feed sludge seems to influence the
performance of BVFs to a greater extent than VPFs. It has been experienced that, at
a higher level of VTS, the cake layer becomes thinner, comes off the filter cloth less
readily and, along with the clogging of the filter cloth, makes it unfeasible to filter.
b. VPFs are run batchwise in a cycle comprising filtration, squeezing and cake
discharge because of its mechanism. Therefore, the filtration rate is lower than that
of the BVF but VTS influences to a smaller extent than the BVF.
c. In contrast to BVFs and PFs, SDs dewater by forced consolidation with the
centrifugal force. Therefore, to express its capacity, feeding rate of dry solids
(flow rate X TS) is used. If the flow rate more than the rated capacity is supplied
when TS is low, the holding time shortens and hence the recovery ratio becomes
bad. In practice, the feeding rate of dry solids is about 80% of the rated capacity.
1.2.3 DOSING RATE AND VTS
In Figs. 1.17, 18 is shown the fluctuation in the dosing rate of ferric chloride
and carbide slurry depending upon VTS during dewatering of the elutriated sludge
by the BVF.
In Figs. 1.19, 20 is shown a similar fluctuation during dewatering of the
thickened sludge by the VPF.
In Fig. 1.21 is shown a fluctuation in the dosing rate of the polymeric coagu-
lant depending upon VTS during dewatering by the SD.
108
-------
The present method of dosing control is instrumentally a proportional adding
method to the feed dry solids, but in practice the operator determines the appro-
priate level by observations of the cake coming off the filter cloth during actual
operation. Hence, the scattering in the dosing rate is large, but it may be assumed
that the change in the dosing rate depending upon VTS during dewatering of the
thickened sludge by the VPF is considerable.
In the case of the elutriated sludge, the correlation is small on the same reason
as the aforementioned filtration rate. The dosing rate for the elutriated sludge is
supposed to be smaller than the thickened sludge. The dosing rate of the polymeric
coagulant used in SDs is also influenced by VTS.
1.2.4 WATER CONTENT AND VTS
In Figs. 1.22, 23 are shown relations between the water content of the sludge
cake and VTS for respective dewatering machines.
Water content of the sludge cake is also influenced by VTS. Water content of
the cake is the highest in the BVF. The performance of the SD is most drastically
influenced by VTS, and at a higher level of VTS, the water content of the cake is
about the same as that of the BVF.
109
-------
Fig. 1.14 TS vs. VTS
Fig. 1.15 Seasonal Fluctuation of VTS of Thickened Sludge
•A blulmlnJ Sludge I Ha ml
0 Digc^cJ SluJpt INjmhi
0 DiiteileJ Sludge iChuhu
I. 40
o. Chubu (Started in 1962)
A. Nambu (Started in 1965)
0. Hokubu (Started in 1968)
O, Second Totsuka (Started in 1973)
Oct. Nov. Dec. Jan. Feb. Mar. Apr May Jun. Jul. Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr.
T975 1976
Month, Year
-------
Fig. 1.16 Filtration Rate vs. VTS
Fig. 1.17 Dosing Rate (Ferric Chloride) vs. VTS
JO 40 50 60 70
(Elulniled Shidtt.Oiubu)
30 40
SO 60
Fig. 1.18 Dosing Rate (Carbide Slurry) vs. VTS Fig. 1.19 Dosing Rate (Ferric Chloride) vs. VTS
fThu-kerwJ Smdfr
ndTolwkal J
30 40 SO 60
VTS(It
111
-------
Fig. 1.20 Dosing Rate (Carbide Slurry) vs. VTS Fig. 1.21 Dosing Rate (Polymeric Coagulant) vs. VTS
_J L
Fig. 1.22 Cake Water Content vs. VTS
Fig. 1.23 Cake Water Content vs. VTS
o BVF (Eluirmed Sludic.
O VPF (Thickerwd Slud»c
Second Toltukal
£ 60
e
40 SO
112
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1.3 EVALUATION OF THE DEWATERING MACHINES
In preceding sections the present state of the mechanical sludge-dewatering in
Yokohama City and characteristics of various dewatering facilities and dewatering
processes have been explained. In the following we attempt to evaluate dewatering
machines on the basis of those informations.
1.3.1 THE RANGE OF COMPARISON
Dewatering efficiency, sludge management cost and the like were calculated for
each of the cases listed in Table 1.9 for respective dewatering machines for com-
parison.
Table 1.9 Conditions for Comparison of the Dewatering Machines
Dewatering Machines
Types
BVF
VPF
HPF
SD
Working Time
(hours)
7
24
Capacity
Of Maximum Capacity
Possible Now
Feed Sludge
Kinds
Thickened
Sludge
VTS (Z)
35
47
60
Dry Solids
(t/day)
10
20
30
40
50
* VTS at 35% was the average concentration when the operation was started.
VTS at 47% was the annual average concentration in 1975.
VTS at 60% was the average concentration during winter in 1975 - 6.
Although not all of these cases are feasible, but the factors were calculated to
know the main trend.
1.3.2 THE METHOD OF DETERMINING THE CAPACITY OF THE
DEWATERING MACHINES
For evaluation it is important to know how the capacity of various dewatering
machines changes depending upon the fluctuation of various conditions.
Here the linear functions obtained from the information in Section 1.2 in
which the various properties of the machines including the dewatering capacity were
studied are used. These functions are shown in Table 1.10.
The accuracy of these functions has to be determined by further research and
analysis, but the main trends are to a large extent in agreement with the actual
experience. As to the filtration rate and the water content of the cake for BVFs, the
actual result of treating the elutriated sludge was used, and as to the dosing rate the
actual result by VPFs was used.
The results in Table 1.10 are shown schematically in Figs. 1.24 'v 28.
In Fig. 1.24, the capacity of the HPF was calculated by assuming the cycle time
of 30 minutes while that of the VPF is 20 minutes.
Other assumptions are listed in the bottom column of the Table of Comparison
(cf. Table 1.11).
113
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Table 1.10 Characteristics of the Capacity of Respective Dewatering Machines
(The Results of Operation Depending Upon VTS)
X = VTS
"- ^Types of
^~~"-~-~L^Ma ch i ne s
Items ^^"--^^^
Dewatering Rate
(Kg/m2.h)
s~\
B^
CO
0)
4-1
<3
60
c
•rl
01
&
B~!
01 r*.
M^a-
•o .
3 HI
H >
o> o
11 £
Jd S
O ro
•H en
jn H
H >
cu
T) t^
•H >->
J= M
VJ 3
M ,H
O CO
HI
•rl -H
1-1 H
H O
01 r-l
^g
Cake Water Content
(%)
BVF
33.06-0.415X
Y=0.409**(«S=50)
Same as Right
Same as Right
68.3+0.181X
Y=0.286*(«(=50)
VPF
15.3-0.187X
Y=-0.802**(«i=71)
20.2+0.583X
Y=0.567**(«S=71)
1.0+0.188X
Y=0.667**(«i=71)
38.9+0.455X
Y=0.671**(«!=71)
SD
1200*1(Kg/h)
.Polymeric.
^Coagulant
-0.5+0.034X
Y=0.528**(<4=60)
(30 ^ X <; 50)
37.1+0.844X
Y=0.687**(^=45)
* Significant at P < 0.05
** Significant at P< 0.01
*1 The rated capacity of the SD is assumed 50 m3/h provided TS is 3%. The dewatering rate is
assumed 80% of the rated rate after the past performance in city's treatment plants.
Fig. 1.24 Filtration Rate vs. VTS
E 15
-a
o o BVF
0 0 VPF
D— 0 HPF
Full line indicates the rang
actual results
cof
30 40 50 60
VTS (%)
114
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Fig. 1-26 Doting Ran (Cwtahto Slurry) m. VT8
I0 10 30 40 50 60 70
VTS (%)
Fig. 1.26 Doting Rat* (Farrtc Chtoridt) w. VT8
FuU line Indldlet the
10 :0 30 40 SO 60 70
VTS (%)
Fig. 1.27 Dosing Rate (Polymeric Coagulant) w. VTS
10 20 JO 40 50 60 70
VTS (%}
Fig. 1.28 Cake Watar Content«. VTS
10 20 .'0 40 ^0 60 70
VTS I'll
115
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Table 1.11 Economic Comparison of Respective Dewatering Facilities (Thickened Sludge, VTS 47%)
O\
=J_»__j_r!
'•" I ""
-------
Fig. 1.29 The Amount and the Composition of the Sludge Cake Produced
(Thickened Sludge) Depending Upon VTS
<3
& 40
90
(The Amount of the Feed Dry Solids lot/day)
80 r 80
BVF SD PF
BVF SD PF
I I Water Content
I'.'-.-'.v.'l Coagulant
fe%3 Dry Solids
1.3.3 EVALUATION
An example of the results of calculation within the aforementioned range and
conditions is shown in Table 1.11 (thickened sludge, VTS 47%).
a. The amount and the composition of the sludge cake produced
The amount and the composition of the sludge cake produced by the dewater-
ing process have much influence upon the method and cost of the succeeding treat-
ment and disposal of the sludge. An example of the change in the amount and the
composition of the sludge cake produced is shown in Fig. 1.29 (thickened sludge).
— The amount of the cake produced is determined by the water content of the
cake and the amount of the coagulant used. The water content of the cake is higher
at a higher level of VTS, and its influence is most evident in SDs (cf. Fig. 1.28).
— BVFs produce the largest amount of the cake. This is mainly because of the
high water content of the cake, and, in comparison with SDs, is due to the greater
amount of the coagulant used.
— PFs can maintain a low level of water content and hence produce less cake.
— SDs require lower dosing rate, and hence produce nearly the same amount of
cake as PFs when VTS is not high.
117
-------
b. Sludge management cost
The change in the dewatering cost per ton of the feed dry solids is shown in
Fig. 1.30. The treatment cost was averaged over various amounts of the feed dry
solids for each machine.
An example of the details of the sludge management cost is shown in Fig. 1.31
(thickened sludge, annual sludge management cost at a rate of 50 tons per day).
— The cost increases rapidly as VTS increases.
- The BVF is the most expensive.
- The SD is the least expensive when VTS is not very high.
- The cost of the HPF is relatively low mainly because the water content of
the cake is low in comparison with the BVF and the capacity of the machine is large
in comparison with the VPF.
- As to the detail of the cost, the disposal cost is the largest and the coagulant
cost follows it.
— It is characteristic to large cities in Japan that the disposal cost occupies a
large portion of the total cost. Hence, if we exclude it from the total cost, the cost
of the BVF and the SD is smaller than that of the PF. However, the cost of drying
and incineration is greater than the disposal cost. Therefore the machines which
produce cakes with low water content are advantageous.
- As to the fixed cost other than the disposal cost and the coagulant cost, the
SD is the cheapest.
— The depreciation cost of the SD is the smallest. This is because SDs require
small number of auxiliary devices and hence the building cost is small.
- There are many kinds of polymeric coagulants used for the SD. The function
for the dosing rate used for the present analysis holds for only one kind of the
coagulant, and the dosing rate is assumed to increase in proportion to VTS. There-
fore, if other appropriate coagulants are used when VTS is high, the cost may
become considerably low.
Fig. 1.30 Sludge Management Cost per Ton of Feed Dry Solids
(Thickened Sludge) Depending Upon VTS
30 40 50 60 70
VTS (*)
118
-------
Fig. 1.31 Annual Sludge Management Cost Depending Upon VTS
•s
o
3.0 -
2.5 -
2.0 -
1.5 -
1.0 -
0.5 -
3.22
(Thickened Sludge, The Amount of the Feed Dry Solids 50t/day)
2.44
1.97
2.91
2.89
2.70
35 47 60
VTS (%)
BVF
35 47
VTS (
SD
60
35 47 60
VTS (%)
VPF
35 47 60
VTS (%)
HPF
119
-------
Fig. 1.32 Area of Installation for Respective Dewatering Machines
Depending Upon VTS
4,000
3,500
3,000
5.500
5,000
10 20 30 40 50
10 20 30 40 50
The Amount of the Feed Dry Solids (t/day)
10 20 30 40 50
c. The area of the installation
In Japan the land available for the treatment plant is generally limited due to
the shortage of land. The space for installation is also a big problem in modification
and expansion of the sludge treatment facilities. Therefore, in Fig. 1.32 are shown
areas of installation per daily feeding rate for respective dewatering machines.
— The area of installation is generally large for machines which require aux-
iliary devices. The area is large in the order of
a PF, a BVF and an SD.
There is little difference between a VPF and an HPF because an HPF has a large
capacity per a machine than a VPF.
— The performance of the SD is not influenced by VTS because of its mecha-
nism of dewatering. The number of the machine required is determined by the
feeding rate.
- In the PF and the BVF, the increase in VTS brings about the decrease in the
filtration rate and the increase in the dosing rate. Therefore, an increase in VTS as
well as in the feeding rate brings about a rapid increase in the area of installation.
d. Maintenance
The characteristics and problems in operation and maintenance are listed in
Table 1.2. Though it is difficult to evaluate, some of the points that may be men-
tioned are as follows.
120
-------
— The operation of the dewatering process is superior in the order of
anSD, aPF and a BVF
taking continuous automatic operation as the standard.
— As to the treatment process of the sludge cake (drying and incineration), the
machines are advantageous in the order of
aPF, anSD and a BVF
from the view point of the water content of the cake.
— Disposal of the sludge cake (land fill) is easy in the order of
a PF, a BVF and an SD
because of the properties of the sludge.
e. Some comments on the evaluation
Evaluation of various dewatering machines has been attempted on the basis of
the operating experience. Some points which should be kept in mind will be listed.
— The data for determination of the capacity of the dewatering machines were
obtained by analysis of the actual operation, and hence do not necessarily reflect the
true causal relation. Therefore, some of the actual values may change drastically by
further research and analysis.
— As to the annual sludge management cost, because both the quality and the
.quantity of the sludge fluctuate, the cost should be integrated for each dewatering
machine according to this fluctuation to know the cost for respective treatment
plants.
— The sludge management cost is largely influenced by such factors as the
length of the operating time or the capacity of a machine rather than the type of the
machines. Therefore, the estimation of the amount of the sludge produced, determi-
nation of the facilities and the building program based upon the estimate are
important as well as the selection of the machine.
— It is expected that the dewatering efficiency of the same type of machine
may be different depending upon the total sludge treatment system in which the
machine is incorporated.
The ultimate step of the evaluation of the dewatering machine is the choice of
the dewatering machine. For this purpose, it must be first determined into what
kind of sludge treatment and disposal system the dewatering process should be
incorporated. The dewatering machine which is most effective and minimizes the
total cost within the system must be selected. For such a selection, analysis of pro-
cesses other than dewatering is necessary, which will be considered elsewhere.
121
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CHAPTER 2
SLUDGE CONDITIONING BY USING HYDROGEN PEROXIDE
2.1 Introduction 123
2.2 Fundamental Study 123
2.2.1 Leafiest 123
2.2.2 Pilot Plant Test 126
2.3 Results of Batch Test in Full-Scale Plant 128
2.4 Results of Continuous Operation at the Full-Scale Plant 130
2.5 Comparison with Traditional Processing 131
2.5.1 Physico-Chemical Characteristics of the Dewatered Sludge
Cake and Filtrate 131
2.5.2 Disinfectant Action of Hydrogen Peroxide 132
2.5.3 Working Environment 133
2.5.4 Economics 134
2.6 Conclusion 135
122
-------
2.1 INTRODUCTION
The area of sewerage-service region (sewered area) in Osaka City has been
increased to 161.80km2 as of Dec. 20, 1976, meaning that the ratio of the sewered
area to urban area has attained a figure of 88%.
All 12 sewage treatment plants planned to be constructed are in operation,
though some of them are being operated by sedimentation process, and they
treated sewage at an average rate of 2,315,000m3/day in the year between April
1975 and March 1976 to produce dewatered cake of about 500 tons per day.
In Osaka City, the area of which is narrow and mostly urbanized, a site for
sludge disposal is difficult to secure, so that the treatment and the ultimate disposal
of sludge is a very serious problem in sewerage works. Fortunately the problem is
being solved for the time being by using sludge for sea-reclamation works in the
north port establishing service in Osaka Bay, but these reclamation works will be
finished in 1985 according to the present schedule and after 1985 it is considered
impossible to secure a new disposal site in Osaka City.
So far, some sewage sludge, incinerated after mechanical dewatering process by
using such coagulants as ferric chloride, ferrous sulfate and slaked lime, has been dis-
posed to the above-mentioned sea-reclamation area in Osaka Bay. In this dewatering
process, the dosage of so much slaked lime (20 to 50% to dry solid in weight) pro-
vides consequently sludge cake in large quantity. Moreover, when the sludge cake is
incinerated to reduce its quantity, it would not provide function of self-combustion
as the quantity of inorganic substances is relatively large, and it requires not only a
large quantity of supplementary fuel but also incineration produces a great amount
of ash. Thus the purpose of the incineration can not be completely achieved.
To solve this problem, the sludge conditioning process using hydrogen peroxide
was developed through the discovery of the following mechanism;. Organic substances
in sludge are oxidized like a chain reaction by the strong oxidizing action of the
hydroxyl radical generated from hydrogen peroxide in the presence of ferric ion and
also their gel structures are destroyed to isolate water in an accelerated manner, while
ferrous ion turns into ferricion with a high coagulation effect which coagulate sludge
particles to form floes.
Thus dewatering of sewage sludge can be accelelated by two actions, oxidation
and coagulation.
2.2 FUNDAMENTAL STUDY
After the effects of a dosage of chemicals and stirring on the dewatering
characteristic of raw and digested sludges were studied by leaf test in the laboratory,
the operating condition to get design criteria was researched using a pilot-scale plant
of vacuum filter.
2.2.1 LEAF TEST
Mixing Tank: Diameter 15cm x Depth 20cm
Mixing Equipment: Diameter 10cm
Mixing velocity 0 to 1,200 rpm
Fan turbine impeller (6-blades)
123
-------
Leaf Tester: Area of filtering surface 19.6cm2
Degree of vacuum SOOmmHg
Filter cloth Shikishima canvas N74
Both raw and digested sludge collected from the Tsumori treatment plant were
studied by using the above-described apparatus as follows.
a. Dosage of chemicals
A sludge sample of 2 liters was collected in the mixing tank, ferrous sulfate
and hydrogen peroxide were added in varied quantities, and the mixture was
stirred for 10 minutes at the stirring velocity of 200 to 300 rpm. Then the
leaf test was performed to measure the rate of filtration, the water content
of the cake, and the releasability.
The relationship between the filtration rate and the dosage of hydrogen
peroxide at a definite dosage of ferrous sulfate is shown in Fig. 2-1 and in
Fig. 2-2. And the relationship between the filtration rate and the dosage of
ferrous sulfate at a definite dosage of hydrogen peroxide is shown in Fig. 2-3
and in Fig. 2-4.
Fig. 2-2 Relationship between Filtration Rate
Fig. 2-1 Relationship between Filtration rate
and Dosage of Hydrogen Peroxide
— 20-
515-
10-
Tested Sludge: Digested and
elutriated Sludge
Sludge
Concentration: 6.3%
Dosage of FeSO4 ' 9000mg/' Constant
(14.3%)
750 1500 2250 3000 3750 (ppm)
1.2 2.4 3.6 4.8
^ Dosage of H2 Oi (to Dry Sol id %)
Fig. 2-3
20
Relationship between Filtration Rate
and Dosage of Ferrous Sulfate
o 15
10
Tested Sludge. Digested and
Elutriated Skidge
Sludge Concentration: 6.3%
Dosage of H2 O2: 1,500mg// constant
I ___^
4500 6000 7500 9000 10500 12000 (ppml
~Ti£U5TTg iTs 16.6 19.0
—=- Dosage of FeSCM (to Dry Solid %)
25H
E
•a
•20-
10-
1
and Dosage of Hydrogen Peroxide
Tested Sludge. Raw Sludge
Sludge Concentration: 5.37%
Dosage of FeSO4: 5000 mg/1 Constant
600 1000 1400 1800 2200 2600 3000(ppm)
l 1 1 1 1 1 r—l 1 1 1 1 1—
1.1 1.9 2.6 3.4 4.1 4.8 5.6
Dosage of HjOs (to Dry Solid %)
Fig. 2-4 Relationship between Filtration Rate
and Dosage of Ferrous Sulfate
13-1
12-
w
OT
It
"jB 10-
FeSO4-H2O2 Equimole
Tested Sludge: Raw Sludge
Sludge Concentration:3.58%
Dosage of H202: 1,500mg// constant
1500 3000 4500 6000 7500
4.2
8.4 12.6 16.8 21.0
Dosage of FeS04 (to Dry Solid %)
124
-------
From Fig. 2-1, 2, 3 and 4, the filtration rate indicates approximately its maxi-
mum value near the equimolecular value of ferrous sulfate to hydrogen pero-
xide. Then the relationship between the filtration rate and the dosage of
chemicals at a definite mole ratio of ferrous sulfate to hydrogen peroxide is
shown in Fig. 2-5.
Fig. 2-5
Relationship between Filtration Rate and
Dosage of Chemical at a constant mole ratio
I 23-
Tesled Sludge. Digested and
Elutriated Sludge
Sludge Concentration 7 3%
Mole ratio of FeS04 to
H20a. 0745
6000 7500 9000
10500lppm|
2250 2700 3150lppml
—:*. Dosage of H2O2
From the above results it has become obvious that this process can be used
for dewatering if ferrous sulfate of 10 to 15% to dry solid in weight is
added and hydrogen peroxide of 1,500 to 2,500 ppm to sludge slurry in
volume is added for raw sludge or for digested sludge, and that the dewater-
ing process can be further improved in the region of the mole ratio of 0.6 to
1.2 of ferrous sulfate to hydrogen peroxide.
b. Flocculating condition
After a sludge sample of 2 liters was poured into the mixing tank and hydro-
gen peroxide at isoo mg/i and ferrous sulfate of 6000 mg/i were added, the ef-
fects of the mixing velocity and mixing time on the fitration rate were
studied.
The relationship between the filtration rate and the stirring time at a stirring
velocity of 100 to 300 rpm is shown in Fig. 2-6 and that at the mixing velo-
city of 300 to 900 rpm is shown in Fig. 2-7.
Fig. 2-6 Effect of Stirring Velocity and Stirring
time on Filtration ratt.
10-Orpm
200rpm
300rpm
flaw Sludge Concentration: 3.6%
Dosage olHjOj. LSOOmg//
Dosage ot FeSO: B.OOOmg//
(16.79H
Fifl.
5 10 IS 20 25 30
*• Stirring time (min.t
I. 2-7 Effect of Mixing Velocity on
Filtration rate
0—•© Mixing time of H202:10rr
0—0 Mixing time of H202:30min.
A—-&. Mixing time of Lime : 10 mm.
A—-A Mixing time of Lime 30min.
300 500 700 900
a. Mixing Velocity {rpm)
125
-------
According to the above results, the mixing tank should be designed to mix
its contents homogeneously in as short a time as possible, while the floccula-
tion tank should be designed to provide as slow a velocity as possible in
order not to give excess shear stress. As the sewage sludge is a Bingham
fluid, of which the yield point becomes higher with higher concentration,the
sludge can not be mixed homogeneously without a considerably high rota-
tion when the diameter of an impeller to that of the tank is small, but the
shear stress is consequently increased to destroy floes at high rotation.
Therefore slow rotation and a large ratio of the diameter of the impeller
compared to that of the tank are advantageous for a flocculation tank.
2.2.2 PI LOT PLANT TEST
A dewatering test was carried out by using the apparatus shown in Fig. 2-8 to
confirm the leaf test results under nearly the same conditions as at an actual plant,
and by using a sample of raw sludge mixed with digested sludge from the Tsumori
treatment plant. The effects of added chemicals, sludge concentration, the vacuum
filter operating condition, and sludge flocculation on the filtration rate were
examined in checking its stability as regards continuous operation.
Fig. 2-8
Outline of Pilot Plant
l Mixing tank
If
COjCNj.
TBcm
. 20cm
Flocculation
tank
Belt Type Vaccum Filter
Effective Filtering
Surface: 0.54m2
Sludge holding FeSO4 H202
tank 500^ Solution Solution
tank tank
126
-------
From those results shown in Fig. 2-9 to Fig. 2-14, the following was confirmed.
Fig. 2-9 Relationship between Filtration Rate and
Dosage of Hydrogen Peroxide
25-
.c
c«
0)
ro
c20
_o
ro
U_
1
15
/68.5%
/ 3.0mm
67.3%
3.0mm
Drum Rotation
•—• 115 sec/cycle Velocity
a—0 200 sec/cycle
FeSO4/HjO2 =1 (mole ratio)
Sludge Concentration: 6.3%
Dosage of FeSO* : 8,500mg//
,,
2000 ' 2500
Dosage of HjOj Img/ S )
Fig. 2-10 Relationship between Filtraton
rate and Sludge Concentration
28
-16-
c
o _
Drum Rotation Velocity
•—• 90 sec/cycle
O—-o 200 sec/cycle
3 4 5 6
• Sludge Concentration 1%)
Fig. 2-11 Relationship between Filtration
Rate and Drum Rotation Velocity
or Submerged Filter Surface Ratio
Fig. 2-12 Effect of Stirring Velocity on
Filtration Rate
50-
_ -
«
I30'
^20-
«;
|
I 10-
ii
1 :
1 5-
*~ Ratio 0.34 _
O— — O Submerged Filter Surface £
Ratio 0.24 1 20-
•a -
Ox ? -
\jr>^ s
^s»v I -
^>-N £ 15-
XXv =
\
JV
<*— — o^^^~~^"^~^
^^^^^^
^-^"^^-o
o—o Paddle Type Impeller 050cm
&~ ^ 3-bladed Propeller 032cm
100 200 . 300
Peripheral Velocity (cm/sec.)
1 1 ' l ' ' ' ' l
1 235 10
~^ Drum Rotation Velocity (min./cycle)
Fig. 2-14 Performance on Continuous Operation
Test
Fig. 2-13 Relationship between Filtration Rate I7'0
and Stirring Velocity or Stirring Time |j> |
of Floccutator ^ S 6-°
^30-
|E -
528-
Q)
(0
-26
.2
fD
± 24-
122-
|
S £
(0 u
(J
^ 80
° ^ ^S
'^-- §"70
O ^ '^
A 1 "
O—o Stirring Velocity 10 rpm 5 o 60
A~A Stirring Velocity 40 rpm v —
(0 "C
a: » 21-
c — .
0
-------
* The results at this pilot plant are in close agreement with those of the leaf
test. That is, sludge should be mixed homogenously in as short a time as
possible in a mixing tank, while in the flocculation tank which should be
used like a storage tank, sludge should be agitated as slowly as possible, an
absence of sediment and an impeller having a large diameter being
advantageous.
* Even the dilute slurry of sludge about 2.5% can be stably dewatered without
clogging the filter cloth so that this pilot plant can be actually used.
2.3 RESULTS OF BATCH TEST IN FULL-SCALE PLANT
As the possibility of dewatering of sludge conditioned by this new process was
confirmed from the results of the leaf test and the pilot scale plant test, the full-scale
plant test was carried out at the Nakahama sewage treatment plant.
One of the three mixing devices, which has been previously installed, was
modified for purpose of this test. The flow-sheet and the specification breakdown
of this equipment are given in Fig. 2-15 and in Table 2-1 respectively.
As a sludge treatment system combined by digestion-elutriation-chemical con-
ditioning-dewatering processes in series was being used at this treatment plant,
elutriated sludge after digestion mainly was tested.
However, raw sludge was also tested to some extent taking into account of the
future movement to direct incineration of raw sludge without using digestion pro-
cess.
Fig. 2-15 Flow-Sheet of Full-scale Plant
Flow meter
Digested Sludge
Dilute pump Feed tank Feedpump
128
-------
Table 2-1 Outline of Equipment
Name
1-,
£
:3
bu
-a
a
^
C
CO
H
c
.0
.*_>
«
*3
60
Ifl
0
O
Tested
Sludge
Ferrous
Sulfate
>
H-l
>!H
Mixing Tank
Mixer
Flocculation Tank
Flocculator
Filter
Feed Pump
Feed Tank
Feed Pump
Storage Tank
Dilute Tank
Feed Tank
Dilute pump
Feed Pump
Specification
Diameter 1 .3m x Height 1 .5m x max.
capacity 1.7m3 Stainless steel 304
Pitched paddle type
width 0.65m x 20 ~ 85 rpm x 2.2kW
Width 1 .5m x Length 3.3m x Height
1 .9m x max. capacity 7m3 Steel
Inner surface coated with epoxy resin
Pitched paddle type
width 1 .Om x 10 ~ 40 rpm x 3-steps
impeller 0.75kw
Belt type vacuum filter
Filtering surface area 33m2
Diameter 100mm x Head 13m x capacity
Im3/min. x 15kw
Width 2m x Length 8m x Depth 1.5m
Diameter 50mm x Head 13m capacity
50 Z/min x 0.75kw
Diameter 2.7m x Height 3.7m x Capacity
20m3 Alminium
Diameter 0.65m x Height 1.2m x Capacity
0.3m3 Stainless steel 316
Horizontal type
Diameter 1 .1m x Length 2m x Capacity
2m3 Alminium
Diameter 25mm x Head 10m x capacity
80//min. x 0.85kw
Liquid-contacting part Stainless steel 316
Diameter 50mm x Discharge pressure
2kg/cm2 x capacity 10 ~ 45 //min. x 2.2kw
Liquid-contacting part: PVC
1
1
1
1
2
2
1
2
1
1
1
2
2
The effects of the dosage of hydrogen peroxide and ferrous sulfate as well as
the effects of flocculation on the filtration rate for the sludge sample listed in Table
2-2 are shown in Fig. 2-16 to Fig. 2-19. From those results, the data obtained from
the leaf test and the pilot plant test were confirmed to be reproducible by this actual
plant test, and sludge could obviously be dewatered up to the same level as that in
the traditional process if flocculation is done carefully.
Fig. 2-16 Relationship between Filtration Rate
and Dosage of Hydrogen Peroxide
Fig. 2-17 Relationship between Filtration Rate
and Dosage of Ferrous Sulfate
500 1000 1500 2000 ppm/slurry
Dosage of Hydrogen Peroxide (HsOi)
5 10 15 20 %/DS
Dosage of Ferrous Sulfate |FeS04) lo Dry Solid.
129
-------
Fig. 2-18 Effect of Mixing Time on
Filtration Rate
E
•&
80 rpm
Rotation Number
of Mixer
Mixing Time 1 to 5 min.
Rotation Number
of Flocculator 15 rpm
Stirring Time Continuous
H 1 1 1
2345 min
Mixing Time
Fig. 2-19 Effect of Stirring Velocity oh
Filtration Rate
Rotation Number of
Mixer
Mixing Time 1 i
30 to 80 rpm
Rotation Number of Flocculator 15 rpm 25 rpm
Stirring Time Continu- Continu-
ous
30 40 50 60 70 80 rpm
1,0 1.4 1.7 2.0 2.4 2.7 m/s peripheral
velocity
Rotation Number and Peripheral
Velocity of Flocculator
Table 2-2 Tested Sludge Properties
Digested and
Elutriated
Sludge
Raw Sludge
PH
7-8
6-7
Alkalinity
(ppm)
400 - 600
300 - 400
Dry Solid Con-
centration (%)
3-4
3-4
Content of Organic
Matter (%)
44-46
55-60
Furthermore, the test using raw sludge gave the following good results when
hydrogen peroxide and ferrous sulfate were added at the rates of 1,400 to 1,500
ppm to sludge in volume and at 13 to 19% to dry solid in weight respectively;
The filtration rate was 11 to 19kg/m2/hr, the water content of the sludge cake
was 75 to 77% and the thickness of the dewatered sludge cake was 4mm.
2.4 RESULTS OF CONTINUOUS OPERATION AT THE FULL-SCALE PLANT
On the basis of full-scale plant test results which showed that this process can
in fact be used for dewatering process, the Nakahama sewage treatment plant has
been using this new process exclusively since the end of October 1976. At present
50 to 70 tons of dewatered sludge cake per day can be obtained from slurry sludge
with a concentration of 3 to 4% at a rate of 400 to 500m3 /day under the following
operating conditions; dosage of hydrogen peroxide - 1,200 ppm, dosage of ferrous
sulfate - 15%, mixing velocity - 80 rpm, mixing time - 2.5 minutes and stirring
velocity - 15 rpm.
As the sludge cake of 70 to 100 tons/day was produced by dewatering 300 to
400m3 /day of slurry sludge with the traditional process, it was considered that this
new process achieved the aimed for purpose. Moreover, in the traditional process
the life of the filter cloth was 300 to 400 hours at most even though it was washed
with hydrochloric acid on occasion due to clogging of the filter cloth, but this new
process lengthened the life to over 700 hours with no-mesh-clogging, this being due to
the easy cloth-releasability of sludge cake. The life of the filter cloth will depend on
the strength of the fiber making up the cloth.
130
-------
2.5 COMPARISON WITH TRADITIONAL PROCESSING
Though the time the new process was actually utilized in a full scale plant was
too short and the quantity of sample collected was too small to allow a complete
study, this new process was compared with the traditional one and discussed using
the data obtained in this fundamental research.
2.5.1 PHYSICO-CHEMICAL CHARACTERISTICS OF THE DEWATERED
SLUDGE CAKE AND FILTRATE
The characteristics of the dewatered sludge cake and filtrate obtained with this
new process and with the traditional one are shown in Tables 2-3 and 2A respec-
tively. The dewatered sludge cake obtained with this new process contains slightly
more water than that with the traditional one but sludge releasability from this new
process is excellent even at a thickness of 2mm and the cake contains more organic
substances, approximately the same level as that in sludge used for dewatering, than
that with the traditional process. Accordingly, its heat value per unit weight is
higher so that it would be better for incineration when it is made a common prac-
tice. On the other hand, pH of the filtrate indicates pH of 4 to 6 this being weakly
acidic, therefore accessory apparatuses may be corroded though the corrosion de-
pends on these used materials.
Table 2-3 Properties of Dewatered Cake
^~^^-^_^ Sample
Measured iterrT~-^^^^^
Cake thickness (mm)
Water content of
Cake (%)
Content of organic
matter (%)
Heat value (Kcal/kg)
Digested and Elutriated Sludge
H2O2
2- 5
72-80
45
2,500
Ca (OH)2
3- 5
70-76
<40
< 2,000
Raw Sludge
H2C-2
2.5- 5
72-80
55-60
3,100
Table 2-4 Properties of Filtrate
Measured Item
PH
SS mg/1
BOD mg/1
COD mg/1
T-Fe mg/1
H2O2 Method
4-6
1 50 - 400
100-300
100 - 300
20 - 1 ,000
Ca (OH)2 Method
12-13
150-400
—
-
10-20
The concentration of total iron in the filtrate from this new process sharply
fluctuates from 20 to 1,000 ppm. The reason is thought to be that iron begins to
exude easily when the mole ratio of ferrous sulfate to hydrogen peroxide is over 1.
In Osaka City, sludge is used for sea-reclamation at present as described above.
However if the sludge is approved as a harmful industrial waste (if it does not pass
the check test contained within the Harmful Industrial Waste Code established under
the Cabinet Order for Implementation of the Waste Management Law) it can not be
reclaimed as long as it is given no special treatment. Therefore, dewatered cakes
from this new process and traditional processes and their ash incinerated with an
131
-------
electric furnace at 800° C in a laboratory were checked according to the established
method, and this new process was compared with the traditional process. The
results are shown in Table 2-5.
Table 2-5 Heavy Metal Content and Results of Exudation Test in Dewatered Sludge Cake and Incinerated
Ash.
\
Water con-
tent (%)
Organic
matter (%)
pH
Cd
Pd
T-Cr
Cr+6
Zn
Mn
Ni
Cu
As
T-Hg
T-Fe
CN
Dewatered cake
Ca (OH)2 method
Dry
solid
69.0
39.4
-
5.48
562
395
-
3425
1055
-
436
6.7
2.57
46600
35.4
'. Exuda-
•tion
-
-
12.8
0.01
0.20
ND
-
0,78
ND
-
0.87
ND
ND
0.30
ND
H2O2 method
Dry
solid
72.7
60.1
-
13.0
818
606
-
3510
563
879
768
2.2
3.4
58600
5.5
Exuda-
tion
-
-
-
ND
ND
0.04
0:09
3.0
6.1
0.40
0.05
ND
0.0015
43
ND
Incinerated ash
Ca (OH)2 method
Dry
solid
-
0.7
-
2.25
415
230
-
2800
320
-
315
3.94
ND
47500
0.37
Exuda-
tion
—
-
12.7
ND
0.13
ND
0.09
0.18
ND
-
0.34
ND
ND
0.40
ND
H2O2 method
Dry
solid
—
-
-
24.9
1068
1700
-
6870
1420
150
1520
13.7
0.13
97500
-
Exuda-
tion
—
-
6.7
ND
ND
0.1
0.09
ND
0.6
ND
ND
0.09
0.0007
0.1
-
Judgment criteria
for harmful indus-
trial wastes (for
exutation)
0.3
3
1.5
1.5
0.005
1
Heavy metal content: ppm
The content of heavy metals in the dewatered sludge cake and their ash from
the traditional process in which slaked lime is added is naturally lower and the pH of
the exudation from the traditional process is higher due to the addition of slaked
lime so that it is difficult for heavy metals to exude.
But the exudation quantity of heavy metals in either process is lower than the
regulated value.
But care should be taken here in that six valent chromium was detected in the
incinerated ash from this new process. It is presumed that the six valent chromium,
detected only in this case, can be attributed to the following;
* high chromium content in the incinerated ash,
* high lime content in the filtrate and high lime content in the sludge used for
dewatering due to returning of filtrate and waste from the slurry vat.
At any rate the volume of dewatered sludge cake produced in this new process
will be smaller than that in the traditional process, but the possibility that three
valent chromium might be oxidized (to six valent chromium)in the incineration of
sludge cake can not be denied.
This problem will be further studied in full-scale plant operation in the future.
2.5,2 DISINFECTANT ACTION OF HYDROGEN PEROXIDE
In sewage sludge, various bacteria, viruses and parasites are present. The disin-
132
-------
fectant action of hydrogen peroxide was examined by using the number of coliform
groups as a contamination index for fecal coliform bacteria, which is shown in Table
2-6. The number of coliform groups measured in the sludge collected from the slurry
vat of the full-scale vacuum filter is shown in Table 2-7. In each cases, the
disifectant action of the hydrogen peroxide is recognized to be significant.
Table 2-6 Disinfectant Effect of Hydrogen Peroxide on No. of Coliform Group.
~"~~~~~- — — Sample
Dosage of Hz 02 ~~ — — _______
0(mg/l)
1000
1500
2000
2500
Digested Sludge
1.5 x 10s (No./ml)
3.7 x 103
5. Ox 1Q2
5.0x10*
8
Raw Sludge
2.4 xlO6 (No./ml)
4.3 x 103
2,0 xlO3
3.0x10'
3
Dosage of FeSO*: 6000mg/l
Table 2-7 Number of Fecal Coliform Groups in Sludge with Full-scale Plant
~~~^~-~^^^^ Sample No,
Kind of sampk~~~~— --^.^
Digested and elutriated
sludge
Chemical conditioning
sludge
1
3.8 xlO6
2.0 xlO2
2
5.8 xlO4
6,9.x 102
3
8,3 xlO3
3.Jxl02
2.5.3 WORKING ENVIRONMENT
The working environment in terms of such things as dust or nasty odors often
becomes a problem while sludge dewatering operation. There is no dust problem in
this new process which handles ho powdery lime for sludge conditioning.
For odors, 5 components, which were thought to be released from sewage
sludge, of 8 substances of which the maximum contents are regulated by the Malo-
dor Control Act were selected and their concentration measured while the filter was
being operated. The results are shown in Table 2'8. From those results, this new
process was considered to be effective for ammonia odor control, Though the posi-
tive deodoring effect by this new process could not be recognized only from the
above results, it was significantly felt.
133
-------
Table 2-8 Result of Malodoreous Substances Measurement around Filter
N\. Sample
Measured N.
Item X^
Hydrogen
sulfide
Methyl
mercaptan
Methyl
sulfide
Trimethyl
amine
Ammonia
HlOa method
Sludge-feed-
ing side
(inside slurry
vat)
ND
ND
1.6
m
ND
Cake-releasing
side around
drum
ND
ND
0.4
ND
ND
Ca (OH)2 method
Sludge-feed-
ing side
(inside slurry
vat)
ND
0.3
1.4
ND
400
Cake-releasing
side around
drum
ND
ND
0.5
ND
ND
Regulated
standard value
on site
boundary
20 - 200
2-10
10-200
5-70
1000 - 5000
Unit: nl/l = ppb
2.5.4 ECONOMICS
Table 2-9 shows the rough calculation of the required cost for this process in
comparison with the traditional process when 100 tons of sludge as dry solid in
weight per day is treated. Though some of operation and maintenace costs were dif-
ficult to estimate over a long term, it was proved that within the limits indicated in
Table 2-9, this process was feasible from an economic standpoint as well.
134
-------
Table 2-9 Comparison of Dewatering Process by Using Hydrogen Peroxide System with Slaked Lime System
\
It
Chemical Conditioning Method
em\^ Kind of Sludge
Raw Sludge (dry solid)
Digested Sludge (dry solid)
Chemical Dosing Rate
Sludge Cake Water Content
Heat Value
Products
Incinerated Ash Products
Cost Comparison
Construction Costs
Operation and Maintenance Cost Per Year
Depreciation & Interest
Chemical Cost
Supplemental Fuel Cost
Boiler for Digester
Heating
Furnace for Incinerator
Ultimete Disposal Costs of Ash
Electricity Water Supply Costs
Repair Material
Labor Cost
Total
Operation and Maintenance Cost
Per 1 Ton of Dry Solid
H2O2 + FeSO4
Digested Sludge
100 t/day
70 t/day
H2O2: 2.5 -5%
(average 3.75%)
FeSO4: 10-20%
(average 15%)
70 - 80% (average- 75%)
average 2143 Kcal/kg
280 t/day
52 t/day
12,944 million yen
600 million yen
H2 02 : 70 t/day x 0.037 5
/t= 273,750,000 yen
FeSO4: 70 x 0.15 x
OY x 365 x 800
= 6, 130,000 yen
Total = 279, 880,000 yen
36.65 1/t x 100 t/day x
365 x 33.80 yen//
= 45 ,220,000 yen
110.55 x 100 x 365 x
33.80= 136, 390,000 yen
Total = 181,610,000 yen
52 t/day x 365 x 4,922
yen/t -93,420,000 yen
¥318,350,000
¥83,000,000
¥400,000,000
¥1,956,260,000
¥53,600
Raw Sludge
100 t/day
H2O2: 2.5 - 5%
(average 3.75%)
FeSO4: 10 - 20%
(average 15%)
75 - 80% (average 77%)
average 3000 Kcal/kg
435 t/day
52 t/day
8,203 million yen
410 million yen
H202: 100 t/day x 0.0375
x Q-|J x 365 x 10,000yen/
t- 391, 100,000 yen
FeSO4: 100 x 0.15 x
Oy x 365 x 800
= 8,760,000 yen
Total = 399,860,000 yen
69.08 1/t x 1 00 t/day x
365 x 33.80 yen//
= 85,220,000 yen
Total = 85,220,000 yen
5 2 t/day x 365x4,922
yen/t = 93,420,000 yean
¥178,380,000
¥63,000,000
¥305,000,000
¥1,534,800,000
¥42,100
Ca (OH)2 + FeSO4
Digested Sludge
100 t/day
70 t/day
Ca (OH)2 (average 25%)
FeSO4 (average 5%)
65 - 75% (average 72%)
average 1714 Kcal/kg
313 t/day
78.4 t/day
13,798 million yen
645 million yen
Ca(OH)2: 70 t/day x 0.25
x 365 x 12,500yen/t
= 79,840,000 yen
FeSO4: 70 x 0.05 x
~ x 365 x 800
= 2,040,000 yen
Total = 8 1,88 0,000 yen
36.65 1/t x 100 t/day x 365
x 33.80 yen/t
= 45 ,220,000 yen
130.97 x 100 x 365 x
33.80= 161,580,000 yen
Total = 206,800,000 yen
74.8 t/day x 365 x 4,922
yen/t = 134,380,000 yen
¥318,230,000
¥ 90,000,000
¥400,000,000
¥ 1,876,290,000
¥51,400
2.6 CONCLUSION
The merits and the demerits of this new process are summarized as follows
along with the problems to be solved in the future.
Merits:
1. Smaller quantity of dewatered sludge cake and incinerated ash.
2. Higher heat value per dry solid base.
3. Simpler equipment, easier operation and maintenance.
4. No need to adjust the conditions for the addition of chemical with a slight
variation in sludge properties and sludge concentration.
5. Higher sludge recovery rate due to the easy releasability of dewatered cake,
longer life of filter cloth, and no need of washing filter cloth with acid solu-
tion.
6. Better working environment.
135
-------
Demerits and problems:
1. Slightly higher water content in dewatered sludge cake than that in the
traditional process.
2. Necessary to prevent the apparatuses from coming into contact with the
liquid due to the possibility of corrosion on account of the weak acidity of
sludge.
3. Slightly higher treatment cost than that with the traditional process.
4. Slight concern for the stable supply of hydrogen peroxide the manufacturers
of which being oligopolistic.
The method and engineering for treating sludge should be comprehensively
discussed as regards ultimate disposal of sludge and effective utilization of the
sludge. In the future, this new process will be studied further in terms of systematiz-
ing the treatment and disposing of the sludge. From this point on, together with the
disposal of waste gas at incineration process, the prevention of apparatus corrosion,
and the structure of the incinerator to be used, the quantitative analysis of the ad-
ded chemical and the mixing conditions that improve the process economically will
be made the subjects of study.
136
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CHAPTER 3. SURVEY OF ECONOMICAL AND TECHNICAL PER-
FORMANCE FOR EMISSION CONTROL EQUIPMENT
INSTALLED WITH SLUDGE INCINERATOR
3.1 Introduction 138
3.2 Historical Review of Emission Standards 144
3.3 Auxiliary Fuel and Design Capacity of Incinerator 148
3.4 Case Studies on Performance of Emission Control Facilities 150
3.5 Tentative Proposal for Standard Emission Control System in Sludge
Incinerators 159
137
-------
3 SURVEY OF ECONOMICAL AND TECHNICAL PERFORMANCE FOR
EMISSION CONTROL EQUIPMENT INSTALLED WITH SLUDGE
INCINERATOR
3.1 INTRODUCTION
At the U.S-Japan 4th conference on Sewage Treatment Technology, a brief
report was presented on the treatment and disposal of sewage sludge in Japan. In
this report, it is noted the remarkable progress of construction of sewage facilities
in Japan accompanied by a very rapid increase in the amount of sewage sludge which
is to be disposed. See Table 3.1.
Table 3.1 Annual Change in Sludge
\
1967
1968
1973
Total
(xlO4 persons)
10,024
10,141
10,871
®
Sewered
Population
(xlO4 persons)
1,112
1,283
2,110
No.
of
S.T.P.
142
175
253
©
Treated Sew-
age Volume
(M-mVyr)
2,371
2,691
5,733
©
Sludge
(99% moisture)
(M;m3/yr)
22,93'
28,19
104,12
©/®
(%)
0.97
1.05
1.82
(m3 /cap/day)
0.58
0.57
0.74
Sewage sludge in 1953 and sewage volume are listed in Table 3.2.
Table 3.2 Generated Sludge Volume by Treatment Process
(1973)
Process
Activated Sludge
process
Trickling Filler
Process etc
Primary Treat-
ment Process
etc
Total
No.
of
S T P
166
69
18
253
«®
Sewage
Volume
1 xlO3 mj/yr)
3.760,401
1.559.601
412.731
5,732,733
®
Sludge
Generated
(xlO'm'/yr)
64,770.3
12.589.5
2,861 4
80.221.2
©
Night Soil
(x]0!m!/yr)
2,688.1
866.4
201 7
3,756.2
®<&
(xlO'm'/yr)
67,458.4
13,455 9
3,063.1
83,977.4
©
Sludge Volume
(99% moisture)
(xlO!m»/yr)
86,567.8
12,916.7
4,630.5
104,115.0
©
Night Soil
(99% moisture)
(xlO'm'/yr)
6,720.3
2,166.0
504.3
9,390.6
®+©
(xlO'm'/yr)
93,288.1
15,082.7
5,134.8
113,505.6
®®
(%)
1.72
0.81
0.69
1.40
®®
(%)
2.30
0.83
1.12
1.82
Approximately 66% of total treated sewage are treated by secondary treatment,
activated sludge process, 27% by modified or trickling filter process and 7% by
primary treatment and 81% of the sewage sludge is generated by secondary treat-
ment process.
So the ratio of the amount of sewage sludge generated to the amount of treated
sewage is 1.72% in secondary treatment, 0.81% in intermediate and 0.69% in pri-
mary treatment.
That is, the secondary treatment process generate greater amounts of sewage
138
-------
sludge which contain relatively higher organic content.
Table 3.3 shows what ways are selected to dispose of sewage sludge.
Table 3.3 Sludge Disposal
(1973)
Process ~^^^^
Reclamation
(Land, Sea)
Disposal on Site in
S.T.P. at the Sewage
Treatment Plant
Dumping into
Ocean
Soil Conditioning to
Farm Land
Others
Total
Sludge Volume
(lO'mVyr)
1,108.5
158.9
175.2
158.0
110.2
1,710.8
Share
'(%)
64.8
9.3
10.2
9.2
6.5
100.0
Land-filling is the most common practice of sewage sludge disposal, with ocean
dumping and agricultural land application both accounting for about 10% each.
However, at the present, ocean dumping has been only practiced at Kitakyushu,
which share very small.
In March 1976, JSWA conducted a survey on sewage sludge incineration facili-
ties in Japan are summarized in Table 3.4.
About 25% of sewage sludge, and about half of the dewatered sewage sludge
are incinerated. Most of these incinerators were located in the 3 major metropolitan
areas (see Table 3.5).
This is the season why it is very difficult to find the site to dispose sewage
sludge and efficiency of transportation is very low by heavy traffic conjestion in
metropolitan areas.
Characteristics of sewage sludge and the performance of sludge treatment
during 1975 in Tokyo, has been summarized in Table 3.6. 44% of the sewage sludge
generated in Tokyo is incinerated, and then disposed to land reclamation site in the
bay. Since sewer system in Tokyo is employed combined system, the contents of
organic matter in the sludge is as low as 40%. In another words inert matters with
surface water are induced to sludge.
The incineration of sewage sludge consumes a large amount of energy and as
will be described later, regulation on atmospheric emissions are becoming more and
more stringent, it is very important to study about performance of actual emission
control equipment of sewage sludge incinerator. In 1975 Research and Technology
Development Division of JSWA embarked on a program of research and development
on the treatment and disposal of sewage sludge. This program includes evaluation of
the land application of sewage sludge as soil conditioner, pyrolysis, and incinerators
itself etc. This paper is an interim report on this subject and this project will be
completed in 1978.
139
-------
Table 3.4 Inventory of Incineration in 1975
(March 1976)
Prefecture
Hokkaido
Tochigi
Saitama
Chiba
Tokyo
City
Sapporo
Sapporo
Sapporo
Utsunomiya
Kawaguchi
Arakawa
Chtba
Ichikawa
Matsudo
Narashino
Tokyo
Hachioji
Machida
Tamagawa
Tamagawa
Name
of
S.T.P.
Soseigawa
Toyohiragawa
Shmkawa
Tagawa
Ryoke
Arakawasagan
Chuo
Ichikawa
Shumatsu
Koganehara
Sodegaura
Sunamachi
Odai
Shmgashi
Kitano
Tsurukawa
Minamitama
Kitatama
Sewer
System
Combine
Combine
Separate
Combine
Separate
Combine
Combine
Combine
Combine
Separate
Combine
Separate
Separate
Combine
Combine
Combine
Combine
Separate
Separate
Combine
Treatment
Process
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Agro
Accelerater
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Types
of
Sludge
Raw
Raw
Raw
Digested
Raw
Digested
Raw
Digested
Raw
Raw
Raw
Raw
Digested
Raw
Digested
Raw
Digested
Raw
Raw
Raw
Types
of
Dewatering
Va
Fp
Fp
Va
Va
Fp
Va
Va
Va
Va
Va
Va
Va
Va
Cf
Fp
FP
Multi-
health
Furnace
17t/Dx3
35t/Dxl
40t/Dxl
50t/Dxl
20l/Dxl
lOt/Dxl
5t/Dxl
150t/Dx]
150t/Dxl
200t/Dxl
250t/Dxl
300t/Dxl
lOOt/Dxl
1501/Dxl
180t/Dxl
180t/Dxl
2001/Dxl
300t/Dxl
5t/Dxl
Fluid -bed
Incinerator
40t/Dxl
20t/Dxl
40t/Dxl
Rotary
Drying
Incineration
30t/Dxl
The Rest
30t/Dxl
42.5t/Dx2
Dewatering
Cake
(t/year)
40.483
14,301
16,910
4,104
5,036
8,080
10,488
3,832
No Data
> 498,770
' 179,145
1, 57,985
J
10,134
No Data
2,977
6,586
Moisture
Content
Average
76.4
50.5
44.1
78.1
70.5
63.0
No Data
75.0
No Data
Raw 79.4
Digested 79.1
20.8
78.0
No Data
63.5
61.4
Incinerated
Sludge (Wet
Cake, t/year)
2,471
10,972
16,230
3,197
5,345
6,392
^^^
1,032
^^^
^-^
50,450
42,812
67,240
77,331
90,765
16,003
33,363
51,606
57,408
50,370
7,615
6,952
^^^
2,900
5,776
Auxiliary
Fuel
(kS/yeai)
(B) 145
(B)*l,256
(B)*l,369
263
251
337
^^
161
\^^
^^
1,712
1,382
2,347
1,429
1,616
345
1,524
980
573
2,985
472
716
^^"
241
782
Digested
Gas
mj/year)
1,412,420
3,434,250
1,401,350
7,430
1,270,810
2,504,120
1,300
Remarks
Suspension of
Operation)
•Heat Treat-
ment
•Heat Treat-
ment
(Suspension of
Operation)
(Suspension of
Operation)
(Suspension of
Operation)
(Suspension of
Operation)
-------
Prefecture
Kanagawa
Toyama
Shizuoka
Aichi
Kyoto
City
Kawasaki
Yokosuka
Odawara
Toyama
Takaoka
Kosugimachi
Gifu
Gifu
Shizuoka
Hamamatsu
Nagoya
•
Nagoya
Ichinomiya
Bisai
Kyoto
Name
of
S.T.P.
Iriezaki
Shitamachi
Kotobukicho
Joka Center .
Yotsuya
Daikakusan
Kokubu
Nanbu
Takamatsu
Chubu
Yamazaki
Shibata
Tobu
Bisai
Toba
Sewer
System
Combine
Combine
Separate
Combine
Separate
Combine
Separate
Separate
Separate
Combine
Combine
Separate
Combine
Combine
Combine
Separate
Combine
Treatment
Process
Activated Sludge
Activated Sludge
Activated Sludge
High Rate Trick-
ling Filter
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
High Rate Trick-
ling Filter
Activated Sludge
Activated Sludge
Types
of
Sludge
Raw
Raw
Raw
Digested
Raw
Digested
Raw
Raw
Raw
Raw
Raw
Digested
Raw
Digested
Raw
Raw
Raw
Raw
Digested
Types
of
Dewatering
Va
Cf
Va
Va
Va
Va
Va
Va
Va
Va
Va
Va
Va
Va
Va
Multi-
hearth
Furnace
40t/Dxl
18t/Dxl
20t/Dxl
30t/Dxl
150t/Dx2
40I/DX2
80t/Dxl
150t/Dx2
5t/Dxl
lOt/Dxl
30t/Dxl
60t/Dxl
60t/Dxl
60t/Dxl
150t/Dxl
150t/Dxl
150t/Dxl
Fluid-bed
Incinerator
40t/Dxl
50t/Dxl
50t/Dxl
Rotary
Drying
Incineration
D.S.
6t/Dx5
30t/Dx2
The Rest
5.2t/Dxl
Dewatering
Cake
(t/year)
13,350
2,994
7,131
2,733
4,630
650
4,768
4,951
8,284
5,921
107,836
No Data
39,240
4,286
3,180
\
, 134,330
,
Moisture
Content
Average
71.0
74.9
77.0
75.0
78.0
75.6
83.2
77.1
70.0
75.0
74.8
No Data
78.1
70.0
60.0
77.3
77.3
77.3
Incinerated
Sludge (Wet
Cake, t/year)
13,350
2,994
6,708
1,307
4,630
250
4,980
3,955
7,212
2,608
59,956
^-^^
38,722
632
900
1,779
4,618
12,659
39,181
38,303
37,790
Auxiliary
Fuel
(ks/year)
1,150
255
916
2.7
120
95
469
501
347
521
2,202
^^
1,657
(B) 29
90
47
310
674
1,660
1,632
870
Digested
Gas
(m'/year)
422,980'
140,960
798,528
Remarks
(Suspension of
Operation)
(Suspension of
Operation)
'Keeping
Warm
(Suspension of
Operation)
-------
t-0
Prefecture
Osaka
Hyogo
Hiroshima
Oita
Wakayama
Okinawa
City
Osaka
Osaka
Sakai
Kishiwada
Ikeda
Suita
Tondabayashi
Sasayamacho
Neyagawa
Neyagawa
Aigawa
Kobe
Nishmomiya
Ashiya
Akashi
Kakogawa
[nagawa
Hiroshima
Oita
Wakayama
Okinawa
Chubu
Name
of
S.T.P.
Tsumori
Hoshutsu
Sanpo
Isonoue
Ikeda
Minami Suita
Kongo
Konoike
Kawamata
Chuo
Suzurandai
Nishinomiya
Ashiya
Hunaue
Ogami
Harada
Enami
fiaiakawa
Shioya
Isahama
Sewer
System
Combine
Combine
Combine
Combine
Combine
Separate
Combine
Separate
Combine
Separate
Combine
Separate
Combine
Separate
Separate
Combine
Combine
Separate
Combine
Combine
Separate
Combine
Separate
Combine
Separate
Combine
Separate
Treatment
Process
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Activated Sludge
Types
of
Sludge
Digested
Digested
Raw
Digested
Digested
Raw
Raw
Ra>v
Raw
Raw
Raw
Digested
Raw
Digested
Raw
Raw
Raw
Raw
Digested
Raw
Raw
Raw
Raw
Types
of
Dewatering
Va
Va
Fp
Va
Va
FP
Va
Va
Fp
Va
Va
Va
Va
Va
Fp
Va
Va
Va
Va
Cf
Multi-
hearth
Furnace
lOOt/Dxl
lOOt/Dxl
200t/Dxl
50t/Dxl
70t/Dxl
15t/Dxl
25t/Dxl
50t/Dxl
70t/Dxl
60t/Dxl
40t/Dxl
15t/Dxl
30t/Dxl
50t/Dxl
27t/Dxl
20t/Dxl
20t/Dxl
50t/Dxl
50t/Dxl
lOt/Dxl
60t/Dxl
Fluid-bed
Incinerator
15t/Dxl
10t/Dx4
Rotary
Drying
Incineration
The Rest
,.••
Dewatering
Cake
(I/year)
11,766
45,802
21,600
4,253
4,419
5,641
3,881
6,385
m3/year
9,033
5,091
1,399
18,052
3,630
3,498
1,651
28,865
20,741
2,400
11,892
444
Moisture
Content
Average
65.0
63.0
68.0
72.5
80.0
65.0
No Data
74.6
69.0
75.5
20.7
57-77
77.5
78.1
65.0
75.8
77.7
75.0
78.0
73.4
Incinerated
Sludge (Wet
Cake, t/year)
10,032
18,148
^^^
^^-^
4,119
^^^
^^"
5,295
9,033
•9,834
468
2,730
3,630
3,498
1,141
24,381
20,741
2,400
10,255
444
Auxiliary
Fuel
(k8/year)
184
"1,183,176
^^
^^
327
^^
^-^
449
280
667
98
122
216
546
63
3,569
1,078
208
No Data
(C) 192
Digested
Gas
(m'/year)
1,350,480
285,288
Remarks
•Gas
Suspension of
Dperation)
(Suspension of
Operation)
(Suspension of
Operation)
(Suspension of
Operation)
Included Taka-
tsuki Plant
Note: Raw . . . Raw Sludge
Digested . -. Digested Sludge
Cf ... Centrifuge
Va . . . Vacuum Filter
Fp . . . Filter Press
-------
Table 3.5
Whole State
(A)
Three
Metropolitan Area
(B)
B/A x 100
Incinerated Sludge x!03W.T/yr
1,015
850
84
Number of Furnace
92
40
45
Note: Three metropolitan - Tokyo, Nagoya, Kyoto-Osaka
Table 3.6 The Status of Sludge Treatment at Metropolitan Tokyo
(in 1975)
Plants
Shibaura
Mikawashima
Odai
Sunamachi
Ochiai
Morigasaki
Shingashi
Total
®
(2)
(3)
®
®
©
®
©
(3)
®
©
©
®
@
(3)
®
©
(3)
)
1,022,380
3,720
2,790
^^-— "^
^_^-~- ~~"
^^- — -~~~~
1.144,340
4,680
•3,140
489,810
4.460
•1,430
^^-— "'
^^^^^
^_-— — ~~~
^^^^~
__^-"
_^~-~-~~\
^^^-^~~
^_^-- "
_^
2,656,530
-
Sludge
Cake
(tons)
123,168
562
337
^_^^"
^_^^--~~~
^^^-— ~~
179,145
772
489
498,770
1,905
1,363
^_^-^-^'
^^^~~~
i__-——^'
\ 160,424
831
438
57,985
236
163
1,019,492
-
-
Slaked
Lime
(kg)
7,057,080
32,900
19,282
^^^
^^-^
^_--— """
10,355,900
50,660
28,300
26,772,970
103,680
73,150
^^-^^
^__-— -""
^^-^^
9,145,380
46,590
24,990
2,718,000
12,500
•7,635
56,049,420
-
Ferric
Chloride
(kg)
3,071,010
14,010
8,391
^^-^^~
^^-— -"'"
_^,^—-^'
6,943,100
20,120
18,970
16,319,180
68,390
44,588
_^-—-^
^_^----"~~~
^^~~~~^
3,878,570
19,430
10,600
990.140
5,030
•2,781
31,202,000
-
-
Incinerated
Cake
(tons)
^_^^~"~
_^^^^~~
^_-^-'~~~~
^^^^~
^_-^^~~"~
^^^^
179,145
-
-
498,770
-
_^-—— -^
^^--^
__^-^~~"
^^--~~^
^^^^
___^— -~~~
57,985
-
735,900
-
-
Remarks
Not
Incinerate
Transported
to Sunamachi
by Pipeline
Transported
to Odai
by Pipeline
Not
Incinerate
Note: 0 Yearly Total
(2) Daily Max
(3) Yearly Mean per Day
* Average
Mikawashima
Odai
Sunamachi
Ochiai
Shingashi
Analysis of Sewage
Raw Sewer
SS
(mg/B)
153
115
109.5
123
89
Thickened Sludge
Moisture
97.5
97.4
95.2
Sludge Cake
Moisture
77.7
79.1
80.8
Sludge Cake
Organic
49.3
36.3
40.4
1975, Yearly Average
The Annual Report of the Sewerage Works Bureau of Tokyo Metropolitan Government
143
-------
3.2 HISTORICAL REVIEW OF EMISSION STANDARDS
Incinerators are required to be equipped with emission control equipment in
order to meet the standard set by Air Pollution Control Law. The survey conducted
by the JSWA showed that installation costs of the emission control facilities ac-
counted for as much as 30 to 50% of the incinerators itself.
Table 3.7 Chronological Regulatory Standards on Control
Law
Smoke and
Soot Regula-
tion Act
(1962-6)
Air Pollution
Contrul Act
(1968-6)
Promulgate
Date
1963-7
1968-3
1968-12
1969-2
1969-7
1971-6
1972-1
1973-1
Object
Area
5
20
27
35
35
The Whole
State
The Whole
State
The Whole
State
SOx
REC0:
0.22% (2200 ppm)
Part 0.28%
0.18% ~ 0.28%
RTE(2):
K = 20.4 ~ 29.2
K= 11.7 ~ 26.3
US® :
K= 11.7 -26.3
UES: (New Facility)
K = 5.26
US:
K= 11.7 -26.3
UES (D : (New
Facility)
K = 5.26
US:
K=7.01 -22.2
UES:
K= 2.92-5.26
US:
K = 6.42~ 22.2
UES:
K= 2.92 -5.26
Particulate Matter
REC: 0.6 - 2.0
e/m3
REC: 0.6 - 0.6
g/m3
REC: 0.6 - 2.0
g/m3
REC: 0.6 - 2.0
g/m3
REC: 0.6 - 2.0
g/m3
Ul: ,.1 -
0.8 g/m3
UES: 0.05 -
0.4 g/m3
US: 0.1 ~
0.8 g/m3
UES: 0.05 -
0.4 g/m3
US: 0.1 ~
0.8 g/m3
UES: 0.05 -
0.4 g/m3
Harmful Matter
No
No
No
No
No
REC:
Cd, 1 mg/m3
a, HCI,
30 - 80 mg/m3
F.I - 20 mg/m3
Pb.10-30 mg/m3
REC:
Cd, 1 mg/m3
a, HCI,
30 - 80 mg/m3
F 1 - 20 mg/m3
Pb, 10-30 mg/m3
REC:
Cd, 1 mg/m3
a, HCI,
30 - 80 mg/m3
F, 1 - 20 mg/m3
Pb, 10~30mg/m3
Note: (D REC - Regulation of Emission Concertration
Q> RTE - Regulation of Total Emission
® US - Uniform Standard
@ UES - Unusual Emission Standard
Installation of Sewage sludge incinerator began in Japan around 1964, and the
emission control regulations were based on the soot and dust control law 1962.
The standards were not so strict ones, so exhaust gas was treated by a water spray
type scrubber (cooling tower) which was sufficient to reduce soot and dust.
In 1976, legislature on Basic Law for Environmental Pollution control was
enacted in 1969, followed by Air Pollution Control Law.
By 1970, the general populace had become keenly aware of pollution problems
and under circumstances which increases in victims from photo-chemical smog, more
144
-------
stringent standard are required. So in December of the same year during the so-
called "Pollution Diet", almost national laws relating to pollution control was
revised. The effect of the revision to the Air Pollution Control Law was to extend
the designated areas covered by the provisions of the Soot and Dust Control Act to
include the whole country. All smoke generating processes in all plants throughout
the country (except mining) had to meet the same emission standards designated by
law. Table 3.6 show how the standards have changed within recent years. The
emission control levels relevant to sewage sludge incineration are listed in Table 3.8.
Table 3.8-1 Emission Standards (Solid Waste Incinerator)*
®
Pollutant
(1) Sulfur Oxdie
(2) Soot and Dust
(3) Harmful
Substances
(4) Specially
Harmful
Substances
(28 Substances)
(5) Heavy Metals
©
Uniform Standard
q -Kx 10° He'
Where
q: Hourly Volume
of Sulfur Oxides
Emitted in Units
of Nm!
H: Effective Height
of Stack
K: Varies According
to the Region
K Ranks are:
3.0,3.5,4.67
6.42,8.76,11.7
14.6, 17.5
Over 40,000 Nm'/hr
0.2 g/Nm! Max.
Under 40,000 Nm'/hr
0.7 g/Nm1
1. Cadmium and Its
Compound 1.0 mg/
Nm'
2. Chlorine 30 mg/
Nm'
3. Hydrogen Chloride
80 mg/Nm1
4. Fluorine, Hydrogen
Fluoride and Silicon
Fluoride 1 ~ 20
mg/Nm1
5. Lead and Its Com-
pound 10-30 mg/
Nm1
6. Nitrogen Oxides
100~480ppm
No
(for the present
No
(for the present)
®
Special
Emission
Standards
K ranks are:
1.17
1 75
2^34
0.1 g/Nm1
0.2 g/Nm'
No
No
(for the
present)
No
(for the
present)
®
Progressive Emission
Standards
Q= a-Wb
Q: Hourly Volume of
Sulfure Oxides
Emitted in Units of
Nm1
W: Fuel Conseemed (kC/
hr)
a: Value designated
Prefectural Govern-
ment
b: 0.8 ~ 1.0
Maximum Pollutants on
the Ground
0= Cm X0o
w= Cmo v
Qo: Sulfur Oxides (in
Nm3/hr)
Cm: Maximum Pol-
lutant Concentra-
tion Disignated by
Prefectures Govern-
ment
Cmo: Maximum Pol-
lutant Concen-
tration Depending
on Qo (Vol %)
No
No
No
No
(D
Special Progressive
Emission Standard
Q=a.Wb + r-a(W + Wi)b-Wb
W, i, a, b as Same as Column
Wi: Aditional Fuel After
Designated Date (kfi/hr)
r: 0.3 -0.7
Maximum Pollutant Concentra-
tion
Cm Qi
Cml
When Additional Facilities are
Equipped
Cm
Q = Cmo + Cmi (Q° + Qi)
Qo, Cm, Cmo as Same as
Column (?)
Qi : Additional on Sulfur
Oxides (in Nm3/hr)
Cmi: Max Pollutant Con-
centration Depend-
ing on Qi (Vol %)
No
No
No
No
©
Local
Ordinaries
No
Yes
Yes
No
No
©
Remarks
K= 1.0, as Guideline
in Some Prefectures
0.01 g/Nm3 as
Guideline in Some
Prefectures
* This Standards will be Applied for the Incinerator which Capacity is Above 200 kg/hr or Grate Area is Above 2 m!.
145
-------
Table 3.8-2 Regulatory Standards on Offensive Odor Substance
®
Substances
(J) Ammonia
(2) Methyl Mercaptan
(D Hydrogen Sulfide
@ Methyl Sulfide
(D Dimethyl Sulfide
(6) Trim ethyl Amine
@ AcetAldhyde
® Styrene
(D
Regulatory Standards
on Boundary Lines
5 ppm
0.002 ~ 0.01
0.02 ~ 0.2
0.01 ~ 0.2
0.009 ~ 0.1
0.005 ~ 0.07
0.05 ~ 0.5
0.4- 2
When Ammonia, Hydrogen Sulfide, Trimethyl Amine
are Concern, Stack Gas Regulatory Standards are
Calculated by Following Equation.
q = 0.108 xHe2 • Cm
q: Flow Rate of Pollutant (m3/hr)
He: Ehective Height of Stack (m)
Cm: Standards as Column (2)
Table 3.8-3 Emission Standards of Nitrogen Oxides
Facilities
4. Portland Cement
5. Nitric Acid Production
6. Coke Oven
Solid Fuel
Others
Gas Volume
(104Nm3/hr)
1^ <10
10<
1<
1 <
1 < <10
10< <4
1 < <4
4<
10<
All Facilities
10<~
Standards
ppm
130
100
480
150
150
100
150
100
250
200
200
On (%)
5
5
6
4
11
11
6
6
10
Os
7
The NOX Emission Concentration shall be Converted through the Following Equation (Except in the Case
of Nitric Acid Production Facilities).
c- 21 -On
C 21 - On A Cs
Where
C: NOX Emission Concentration (ppm)
On: Oxygen Concentration in Stack Gas
Os: Actual Oxygen Concentration in Stack Gas
Cs: Actual Nitrogen Oxides Emission Concentration (ppm)
146
-------
In 1972, scope of standard values were settled according to the Offensive
Odor Control Law. Ammonium, hydrogen sulfide, and trimethylamine were
stipulated according to concentrations in the air at boundary line, while methyl
sulfide, trimethylamine, acetoaldehyde, and styrene were stipulated as concentration
on the ground. According to the Offensive Odor Control Law, local prefecture
designated the relevant areas, and determined appropriate standards. By 1977,
standards had been applied in 450 cities, 463 towns, and 69 villages in 44 prefec-
tures, plus the Tokyo metropolitan area and 10 cities designated by government
ordinance. As an example, standard applied in Tokyo metropolis are shown in
Table 3.9.
Table 3.9 Regulatory Standards of Offensive Odor
3)
(Tokyo)
^"~-\^^ Land Use
(D Ammonia
(2) Methylmercapten
(D Hudrogen Sulfide
® Methyl Sulfide
(5) Trimethylamine
® Acetaldehyde
@ Styrene
(D Methyldisulfide
Industrial Area
Semi Industrial Area
(ppm)
2
0.004
0.06
0.05
0.02
0.1
0.8
0.03
Residental Area
(ppm)
1
0.002
0.02
0.01
0.005
0.05
0.4
0.009
Due to more stringent control of exhaust gas sewage sludge incinerators, the
emission control systems has much improved.
The chronological changes in these systems have been illustrated in Fig. 3.1.
System (1), adopted from around 1964, employed washing by water in a
scrubber for cooling and dust removal. It was quite sufficient at the time to reduce
dust levels to the 0.7 g/Nm3 which value designated by standard.
System (2) in 1970, adoptation of dust removal level was improved to 0.2 g/Nm3,
and because of the lower K value, for control sulfur oxides an alkali cleanser was
added after the scrubber.
System (3) was adapted in 1972 due to a new local ordinances that incinerators
be equipped with electrical dust precipitator (in Osaka and other some prefectures).
System (4) adopted an alkali cleansing, plus after burning for deodorery, due to
the implementation of the Offensive Odor Control Law in 1972.
147
-------
Fig. 3.1 Chronological Variation of Emission Control System for Sludge Incinerator
(0
(2)
(3)
(4) a.
MHF ^ —
MHF |—
MHF j—
Exhausted \___
Gas Fan |~™
Scrubber \__ Chinu
Exhausted \__
Gas Fan \
Scrubber j—
MHF \-| Scrubber V-
MHF \—
MHF N— '
FBH \—
Scrubber ^ —
\ 1 (Alkali)
Scrubber |-j Ablotption
(Alkali) \__ Exhaus
Absorption Column | GasFai
(Alkali) \__ EP
Absorption Column |
(Alkali) \J EP
Absorption Column [ ]
. . . \ l(Acid) \_ (Alkali)
Scrubber | |Ab!orpliol, Column f^ Absorption
iHeat \
Exchanger.) |~~
Heat \
Exchanger-2 j— Cyclo
1
L
ZJ
_ . i-"" Chimny i
Column] |
«ed \J chimny \
V sfsr VI <*«* ^
\ Extuiuted \ 1 Afterburner \
|~" Gas Fin |H (Deodrizition) 1 1
1
^ Chimny ^
\__ ..,. \ I Exhausted \
Columnp EP p] Gas Fan ]~]
1
1 EP N — Chimny \
\ ...... \ Absorption \
ne Y~ Scrubber ^p- ColuTm ^-j
\ Exhausted \ 1 „ . \
|— Gas Fan pj """'' 1
Note MHF - Multi Hearth Furnace
EP Electrical Dust Precipitator
FBF - Fluidized Bed Furnace
HE - Heal Exchanger
3.3 AUXILIARY FUEL AND DESIGN CAPACITY OF INCINERATOR
As of March 1975, 59 plants of the 337 presently operating public owned
sewage treatment plants (that is, 17.5%) have incinerating facilities. Of the total 94
incinerators, 74% were multiple furnace, while fludized bed incinerator and rotary
kilns accounted for 8 to 9%. Design capacity of each incinerator ranged from 5 tons
to 300 tons of wet cake per day. All incinerators designed to handle more than 60t/
day were of the multiple furnace type. Auxiliary fuels were almost always A-heavy
oil, although some employed a digestion gas if it was available.
Table 3.10 lists the auxiliary fuels consumed by 36 incinerators during 1975.
Average consumptions ranges were:-
standingtype: 142-3471/D.T
dynamic type: 228- 561 d/D.T
This wide range in fuel consumption is due to the varying moisture content the
dewatered cake, amount and type of coagulating agent, and daily operating hours.
148
-------
Table 3.10 Auxiliary Fuel Consumption at 36 Incinerators (in 1975)
Process
(Thickening)
I
f
(Dewatering)
1
(Incineration)
(Thickening)
^--^^
s1^ ^^-^
(Dewatering) (Anaerobic
\Digestion)
1
\
(Dewatering)
/
/
(Incineration)
(Thickening) — (Anaerobic
Digestion)
L
(Incineration)— (Dewatering)
(Thickening) — (Aerobic
Digestion)
»
(Incineration)— (Dewatering)
(Thickening) — (Heat
Treatment)
t
(Incineration)* (Dewatering)
Dewater-
ing
Va
Va
Fp
Va
Va
Va
Va
Fp
Cf
Va
Va
Va
FP
Fp
Va
Va
Va
Va
Va
Va
Va
Va
Va
Va
Va
Va
Va
Va
Va
Va
Va
Va
Va
Va
Fp
Fp
Incinera-
tion
MHF
MHF
FBF
MHF
RK
MHF
MHF
FBF
FBF
MHF
FBF
FBF
MHF
MHF
MHF
MHF
MHF
MHF
MHF
MHF
MHF
MHF
MHF
MHF
MHF
MHF
MHF
MHF
MHF
MHF
RK
FBF
MHF
MHF
SGS
SGS
Design
Capacity
W.S.
Tons/Day
10
20
20
27
30
40
40
40
40
50
50
50
40
60
150
200
60
100
150
150
150
150
150
150
150
180
180
200
250
300
30
40
100
25
30
42.5
Yearly
Sludge Cake
W S.
Tons
2,400
3,498
2,900
3,630
7,212
9,834
6,708
5,776
2,994
20,741
4,980
3,955
6,392
9,033
38,722
50,370
12,659
16,003
50,450
42,812
33,363
39,181
38,303
37,790
59,956
51,606
57,408
67,240
77,331
90,765
3,197
6,952
10,032
4,119
10,972
16,230
Cake
ture
%
75.0
78.1
63.5
77.5
70.0
75.5
77.0
61.4
74.9
77.7
83.2
77.1
63.0
69.0
78.1
80.8
77.3
77.7
79.1
79.1
77.7
77.3
77.3
77.3
74.8
77.7
77.7
79.1
79.1
79.1
78.1
78.0
65.0
80.8
50.5
44.1
Consumed
Per Year
Kl
208
546
241
216
347
667
916
782
255
1,078
469
501
337
280
1,657
2-.9S5
674
1,169
1,712
1,382
1,528
1,660
1,632
1,340
2,202
1,728
2,046
2,347
2,259
3,636
263
716
978
329
(B) 1,256
(B) 1,369
Fuel/
Ton-D.S.
8/Ton-D.S.
347
713
228
264
160
277
594
351
339
233
561
551
142
84
195
309
235
328
164
156
205
187
188
156
146
150
160
168
141
193
376
468
279
399
(B)231
(B)151
Note: Va Vacum Filtration FBF -
Fp Filter Press RK
Cf Centrifugation SGS -
MHF - Multiple Hearth Furnace (Bj _
Fluidized Bed Furnace
Rotary Kilne
Step Grate Storker Incinerator
Included Heat Treatment
Table 3.11 Capital Cost of Incinerator In N S.T.P.
(in 1975)
Item
(1) Capital Costs for Civil Engg (x 103 ¥)
Building Costs
Equipment Costs
Total
80,692
603,409
684,101
(2) Capital Cost of Unit Processes
Sludge Cake Feeder
Frame of Furnace
Fuel Feeder
Air Pollution Controller
Ash Conveyer
Electric Power and Measurement
The Rest
Sub Total
69,517
145,986
6,952
88,982
6,952
139,034
145,986
603,409
149
-------
Fig. 3.2 show, relationship between incinerator capacity (and hence size of
incinerator) and the amount of fuel consumed. The relationship between the heat
value of sewage sludge, and auxiliary fuel is now under investigation.
3.4 CASE STUDIES ON PERFORMANCE OF EMISSION CONTROL FACILI-
TIES
In 1975, the JSWA began to investigate actual operating conditions and perfor-
mance of gas emission control equipment. Survey at 13 incinerators was completed
in 1975, and another 5 in 1976. The results of survey on two cases of these inciner-
ators are described in this paper. The multiple furnace at city N P.O.S.T.P. was
equipped with after burner for deodoring following the alkali washing for cleaning
stack gas. The multi-stage incinerator employed in the A P.O.S.T.P of basin wide
sewerage system was equipped with an electric dust precipitator.
(1) Multiple furnace at N P.O.S.T.P.
The sewage treatment plant at city N has a capacity to process 63,000 m3/day
of sewage, servicing a population of about 100,000 people. Activated sludge (step
aeration) method are adopted for sewage treatment. This plant received about
18,000 m3 /day of industrial wastewater from brewery factories.
The two which from multiple furnaces are capable of handling 30 to 50 wet
tons of dewatered sludge cake per day. The exhaust emission from both furnaces is
integrated, and treated as shown in Fig. 3.3. The results of the survey conducted in
December 1975, are shown in Fig. 3.4. Since there was no after-burner at that time,
auxiliary fuel consumption amounted to 27 1/T-WS. Moisture content of the cake
entering the incinerators was low, and the amounts handled were roughly 90% of
design capacity. Consequently, these incinerators operated at relatively high effi-
cienty rates, requiring no more than 342 liter of auxiliary fuel per ton of dry solid.
The ratio of actual supplied air to the theoretical air requirement was 2.2, and incin-
erator operating temperature was at 826° C.
Construction costs have been summarized in Table 3.11. And maintenance
costs etc. are listed in Tables 3.12 & 3.13.
Table 3.12 Running Costs of N S.T.P.
(T) Term of Operating
@ Quantity of Dry Solids
® Personnel
® Fuel
® Electricity
® Water
@ Disposal of Ash
® Maintenance
®+®+®+®+@+®
1,857 hr.
2 730 ton - W.S. x (1 - 0.57) = 1,174 ton
0.632 ton - P.S./hr.
¥2,910,000/person
x 6x4/12 = ¥5,820,000
Heavy Oil (A) 122 k£
¥33.9/2 x 122 x 103 = ¥4,136,000
830,930 KWH
¥9/KWH x 830,930
167,120m3
¥13/m3 x 167,120
Ash 687 m3
¥3,330/m3 x 687 =
Oil Pipe etc. ¥100
= ¥7,478,370
= ¥2,172,560
¥2,287,710
,000
¥21,994,640
150
-------
Fig. 3.2 Fuel Consumption of 33 Incinerators
700
600
a : With After Burning
b : Digestor Gas Included
500
Q
I
400
300
-2 200
u,
fr
100
O : Multi Hearth Furnace
: Fluid-bed Incinerator
x : Rotary Kilne
Step Grate Storker Incinerator
20 40 60 80
100 150 200
Design Capacity of Furnace (Ton/day) Day: 24 Hours
250
300
-------
Table 3.13 Running Cost of
Incinerator in IM S.T.P.
(¥/Ton-D.S.) 1975
1
2
3
4
5
6
7
Item
Personal
(Attendance)
Fuel
Electricity
Water
Absorption Liquor
Disposal of Ash
Maintenancel)
Total
¥/Ton-D.S.
4,957
3,523
6,370
1,851
0
1,948
2,555
21,204
Note: 1) 2% of Capital Cost.
The results of the survey conducted in August 1976 are summarized in Table
3.14, while the operating conditions at the time are shown in Table 3.15. These
results show that although SO2 and dust concentration are below the standard limits
after the cooling tower, there is almost no change in NOx concentration. Odors were
tested according to the 3-point comparison "odor bag" method (used by the Tokyo
Metropolitan, Pollution Control Bureau), employing both physiological odor test,
and analysis of offensive odor substances. In testing the degree of odor in the air
around the plant, a value of 1,400 degree was measured at the washing tower outlet.
Since the height of the chimney was 20 m, it was expected that dispersion would
be sufficient to prevent any offensive odor being noticeable at ground level. Emis-
sion of offensive odor substances was no more than the standard values at boundary
line of the plant, and hence, was not considered to be likely to cause any problem.
Table 3.14 Performance Data in IM S.T.P.
(Aug. 20, 1976)
Item
Feed Cake or Discharged Ash
Aux. Fuel
Composi-
tion Analy-
sis of Feed
Cake or
Discharged
Ash
Moisture
Free Moisture
Ash Content
Sulfur Content
Calorific Value
Unit
kg/h
fi/h
%
%
%
%
KCal/kg
Furnace No. 1
E: Cake
1,040
^^^
73.8
8.4
55.8
2.2
1,930
G: Ash
136
^^-^~
2.43
2.6
89.2
No Data
600
I : A Heavy Oil
^^^-^~~~~
52.5
_^^- — -~""~
^^^^
^^^^~~~~
^___- — ^"^
_— — -^~
Furnace No. 2
F: Cake
2,000
^^- — ""
63.3
8.4
53.0
1.8
2,150
H: Ash
368
^^-^'
0.09
1.4
94.7
No Data
<40
J : A Heavy Oil
^^-^~—~^
20.25
^_^-^--~~
^^-^~
___-— -^
^^---—^
_^~~~~'~~
152
-------
Item
Gas Temperature
Dry Gas Flow Rate
Vapor Flow Rate
Wet Gas Flow Rate
Vapor Volume
Particulate Emission
S02
NOx
HC1
a,
Offensive Odor
Ammonia
Trimethylamine
Hydrogen Sulfide
Methyl Sulfide
Methylmercaptan
Methyldisulfide
Acetaldehyde
Styrene
0,
CO.
Unit
°C
Nm3/h
Nm3/h
Nm3/h
%
g/Nm3
ppm
ppm
Ppm
ppm
-
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
%
%
A
232
8,680
2,570
11,350
23.5
0.545
55.8
99.4
120.07
1.46
6,900
131.54
0.297
1.300
0.143
0.474
0.0005
<1.0
<0.001
12.1
6.7
B
28
9,170
370
9,540
3.9
0.138
11.1
85.1
24.84
1.46
No Data
10.80
0.123
0.436
0.052
0.242
0.0004
<1.0
<0.001
13.0
6.2
C
30
9,535
425
9,960
4.3
0.070
9.8
81.0
17.65
6.11
1,400
8.15
0.067
0.396
0.034
0.182
0.0002
<1.0
<0.001
13.5
4.3
D
68
11,910
585
12,495
4.7
0.034
4.3
71.8
10.38
2.24
No Data
3.83
0.028
0.235
0.017
0.114
0.0001
<1.0
<0.001
15.8
4.2
Standard
____- — ~~~
^^-—-~~~~
________ —
________ — "~~~
______ —
Less than 0.2
Less than 39
______ ~"~
_______---"
______ — — ""~~~
______----~~~
^____— ""
^___— - — ~~~
______ — ~~~~
______---'
^___^^"
_____ — — ~"~~"
_____ -^~~^~
^_____-^"
^___— ^"~~
____ — -^^
Fig. 3.3 Flow Diagram of Facility N
(Sludge Cake)
(!)
(Fuel)
n
(Sludge Ca
Multi Hearth
Furnace
(30 ton/day)
No. 1
L) c^
/^
7>
'
^
Multi Hearth
Furnace
(50 ton/day)
No. 2
Spray Scrubber
(Cooling Dust
Collecting)
Spray Scrubber NaCIO
(Gas Absorption)
Actual Height H0 = 20 m
K Value = 1.75
(Ash)
153
-------
Sludge
Cake
Furnace Feed Rate
kg/h Wet Sludge
Water Cbntent %
Ash Content %
Combustible
Content
Lowes Calorific Value
(D.B.) kcal/kg
C (D, B) %
H (D, B) %
N (D, B) %
S(D,
1,843
67.1 -68.5
15.3-16.1
16.2-16.8
2360-2,500
23.0-23.2
3.5-3.8
3.1 -3.4
1.2-2.1
Ash.
Volume kg/h
Temperature °C
Ignition Loss Wt. %/Solid
Sulfur Weight %
Absolute Specific Weight
300
100
3.46
3.62
3.14
Fig. 3.4 Results of Stack Gas Survey (N. S.T.P.)
1 Multiple Hearth Furnace 50 TONS/day-W.S.
1975-12-12 2 Spray Scrubber (Cooling, Dust Collecting) .... 23,590 Nm3/hr
3. Spray Scrubber (Gas Absorption) 16,720 Nm'/hr
Temperature 10 C 4. Induced Draft Fan (Turbo) 350 m3/min x 55 kW
Humidity - 46% 5. Chimny Height 20 m
6. Axis Cooling Fan 75 m3/min X 7.5 kW
7. Combustion Air Blower 50 m3/min x 11 kW
8. Combustion Air Fan 250 m3/min x 22 kW
30 t/D Furnace
Treated Effluent
I 95 m>
Treated Effluent
I 8 mj/h
3)
Drain — -
Stack Gas
(Furnace Outlet)
Temperature °C
Vapar Volume %
Paniculate Emission
g/Nm3
SOx PPm
HC1 ppm
C12 ppm
NOxppm
col %
O2 %
290
36.6
1.12-1.46
115-123
92-99
1.2-1.3
58-62
9.4
9.2
Spray
Scrubber
®
Stack
Gas
(Chimny)
•N. £
Flow Rate Mm3 /h
Temperature °C
Vapor Volume %
Paniculate Smission
g/Nm3
SOx ppm
HC1 ppm
C12 ppm
NOX ppm
CO2 %
02 %
D
13,000
22
5.1
0.16-0.18
2-12
20
2.2 - 2.7
10-19
4.0
16.0
Stack Gas
(Scrubber
Outlet)
Flow Rate Nm3/h
Temperature °C
Vapor Volume %
Paniculate
Emission g/Nm3
ppm
Dust
Draft Fan J
10,200
15
2.2
0.11
4~12
Sulfur Weight %/solid
Absolute Specific
Weight
3.95
2.63
-------
The quantities of SOx, dust and NOx at measuring points per hour, have been
plotted in Fig. 3.5. Since it is not yet settled standard of concentrations of NOx
emissions for sewage sludge incinerator, the measured concentration were compared
with standards applied to control emission of NOx for boilers. Results showed that
NOx values exceeded this reference values.
Fig. 3.5 Flow Rate of Pollutants (Facility N)
10
E
**-s
0*
- 1.0
- 0.5
(Facility N)
NOX
NOX
SO2
Dust*
Measuring Point
The efficiency of the cooling tower in the processing of gas emissions was quite
evident, but because of the low concentrations of pollutant in the gas phase, it was
not clear whether the cleaning device with chemicals was so effective in removing
these pollutant.
(2) AP.O.S.T.P.
This plant treates 43,000 m3 /day of sewage, and serves a population of 35,000
people. Activated sludge (step aeration) are adopted for treatment. The multiple
furnace can handle 40 wet tons/day. The operating condition are listed in Table
3.16. The gas emission control equipment is shown in Fig. 3.6, and the results of
analysis of the emissions summarized in Table 3.17.
155
-------
Table 3.15 Performance of Incinerator in N S.T.P.
Type
Design Capacity
Dewatering
Chemical Con-
ditioning
Running Time
(Hr/Day)
Keeping Warm Time
(Hr/Day)
Cake Moisture (%)
Incinerated Cake
(Ton/Day)
Aux. Fuel (A Heavy
Oil) (L/Day)
Kerosine (L/Day)
Electricity (kWH/
Day)
Absorption Liquor
(L/Day)
Water (M3/Day)
'Multiple Hearth
Furnace
Fu. No. 1 30 Ton/Day
Fu. No. 2 SO Ton/Day
Fp • Va
Ca (OH)2 + FeCl3
Fu. No. 1: 21
Fu. No. 2: 3
Fu. No. 1:3
Fu. No. 2: 21
Va (Fu. No. 1): 74
Fp (Fu. No. 2): 63
Fu. No. 1 22.40
Fu. No. 2 4.20
3,293
(Fu. No. 1 1,805
VFu. No. 2 1,488
-
4,872
NaOH (Concentration
48%)
208
NaCIO (Available
Chlorine 12%)
305
1,920
Remark
The soot and dust level at the incinerator outlet was found to be 0.086 g/Nm3,
which is much lower than the 1 to 3 g/Nm3 which normally reported irr past data.
This result is attained by which characteristics of applied sludge are stable and
making it possible to operate continually with internal pressures (in the incinerator)
of -1 to -1.5 mmH2O. And this would reduce the level of dust which is found in
the gas emissions. Such stable operating conditions reflect careful and responsible
plant management.
Similar to the dust levels, there was no problem with SO2 levels either, since
levels inside the incinerator were already below the standard emission level. In order
to remove offensive odor, after burner fuel using kerosene. Emission gas was heated
to 750°C, and although there was a slight increase in SO2 level after the deodorizer
stage, analysis of offensive odor gave results which were even better than the perfor-
mance the plant at city N.
NOx levels increased after the after burning.
Operating costs of both incinerators are outlined in Table 3.18. The figures
indicate that the facilities in A P.O.S.T.P cost about 10 times as much as the facili-
ties in N P.O.S.T.P. A major reason for the higher cost is the cost of kerosene used
in the after burning.
156
-------
Table 3.16 Performance of Incinerator in A S.T.P.
Type
Design Capacity
Dewatering
Chemical Condition-
ing
Running Time
(H/Day)
Keeping Warm Time
(HrADay)
Cake Moisture (%)
Incinerated Cake
(Ton/Day)
Aux. Fuel (A Heavy
Oil) (L/Day)
Kerosine (L/Day)
Electricity (kWH/
Day)
Absorption Liquor
(L/Day)
Water (M3/Day)
Multiple Hearth
Furnace
40 Ton/Day
Va
Ca (OH)2 + Fed 3
15
9
83
21.01
2,033
( Incineration 1,676
I Keeping Warm 357
3,795
2,044
NaOH (Concentration
48%) 50
i^liSSy11^
Remark
For After
Burner
Fig. 3.6 Flow Diagram of Facility A
©
(Sludge Cake)
9
Aih
©
(Fuel)
©
(40 ton/day)
Multi
Hearth
Furnace
r
©
71
r
NO
©
Electrical
Dust
Precipltator
(Wet Type)
®-
Actual Height H0 = 20 m
K Value =1.17
157
-------
Table 3.17 Performance Data in A S.T.P.
(Nov. 5,1976)
Item
Feed Cake or Discharged Ash
Aux. Fuel
Composi-
tion Analy-
sis of Feed
Cake or
Discharged
Ash
Moisture
Free Moisture
Ash Content
Sulfur Content
Calorific Value
Unit
kg/h
fi/h
%
%
%
%
KCal/kg
E: Cake
1,620
^^'
82.9
9.0
46.4
0.9
2680
F: Ash
123
^^"
0.5
1.1
95.4
1.5
50
G: A Heavy Oil
__-_—~~ """"
113
___——" "~
______ — -~~~"""'
______ ^
^—^-~~~~^
__—— ""^
H: Kerosine
____— """~~~"~"
270
^-~--~^~~^
^-—-"""^
r___— —""'
__-_^"~'
__-"""
Item
Gas Temperature
Dry Gas Flow Rate
Vapor Flow Rate
Wet Gas Flow Rate
Vapor Volume
Particulate Emission
SO.
NOx
HC1
a,
Offensive Odor
Ammonia
Trimethylamine
Hydrogen Sulfide
Methyl Sulfide
Methylmercaptan
Methyl Disulfide
Acetaldehyde
Styrene
o,
C02
Unit
°C
Nm3/h
Nm3/h
Nm3/h
%
g/Nm3
ppm
ppm
ppm
ppm
-
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
%
%
A
281
4,980
1,310
6,290
20.8
0.086
81.7
126
52.6
0.17
No Data
61.96
0.013
0.095
0.611
0.072
0.007
0.020
0.198
13.8
5.5
B
28
4,970
170
5,140
3.4
0.036
10.4
119
25.1
0.95
No Data
2.80
0.007
0.100
0.003
0.069
<0.001
0.006
0.194
13.9
5.4
C
22
5,190
140
5,330
2.6
0.008
9.5
112
24.1
1.04
No Data
2.09
0.006
0.068
0.003
0.049
<0.001
0.005
0.190
14.4
5.2
D
465
8,260
1,240
9,500
13.0
0.006
16.0
144
9.2
0.15
No Data
2.21
0.010
0.017
0.002
0.011
0
<0.001
0.091
10.5
7.8
Standard
^_-^-~~~'
^__— ---""""""
____- — —~~~~
^___- — —
____^ — — """"
Less than 0.2
Less than 84
"~~
____ — """
_____ -—"
_____ — — — ~"~
^^—- -~~~~~
____- — — ~~~
____—- — - -
-—- -~~""
____— — '
______
_____ — ~~
^___ — -—•"""
______
_____ —-~
158
-------
Table 3.18 Cost Comparison of Incinerators in N & A S.T.P. (in 1976)
Item
Fuel
Electricity
Water
Absorption Liquor
Fuel (Afterburning)
Total
Costs, V/Ton-W.S.
Costs, ¥/Nm3-W.G.
N S.T.P.
2,474 ¥/h
(72.758/h x 34 ¥/B)
l,560¥/h
(156 kWH x 10 ¥/kWH)
Emission Control 700 ¥/h
720 ¥/h
(80 m3/h x 9 ¥/m3)
108 ¥/h
(NaOH 2.4 fi/h x 45 ¥/£)
875 ¥/h
(NaOC1502/hxl7.5¥/8)
^^^^^
5,737 ¥/h
1,887
0.2
A S.T.P.
3,842 ¥/h
1132/hx34¥/e)
l,470¥/h
(147 kWH x 10 ¥/kWH)
Emission Control 960 ¥/h
450 ¥/h
(50 m3/h x 9 ¥/m3)
153, ¥/h
(NaOH 3. 4 2/h x 45 ¥/C)
10,560 ¥/h
(264C/h x 40 ¥/8)
16,475 ¥/h
10,170
1.9
Remark
34¥/fi
(A Heavy Oil)
10¥/kWH
9¥/m3
(Treated Effluent)
NaOH 45 ¥/e
NaOCl 17.5 ¥/6
40¥/C
(Kerosine)
3.5 TENTATIVE PROPOSAL FOR STANDARD EMISSION CONTROL SYS-
TEM IN SLUDGE INCINERATORS
When considering a standard emission control system of gas emissions, it is very
difficult to estimate emission conditions quantitatively because of the considerable
degree of variation in both amount and composition of the exhaust gases being
generated. Emission standard also vary according to location. Summary of the
presently available information on the fludized bed incinerator, and the more
common multiple furnaces, are presented in Fig. 3.7 and Table 3.19. In Fig. 3.7, A
refers to standard control systems, while B refers to cases subject to much more
stringent controls.
The temperature of the emission gas at the incinerator outlet is normally
around 150 to 300°C, so there is little advantage in heat recovery. Because of the 1
to 3 g/Nm3 dust levels at outlet of furnace, a dust removal is incorporated in the
cooling facility, thus alleviating the load of the following washing tower with chemi-
cal or electric precipitator.
159
-------
Fig. 3.7 Flow Rate of Pollutants
(Facility A)
10
E
:z
X
3
Q
0 5
5.
"E
r*
o
^_
^
V
A
*••••
\
\
V
\
\
X.
"
$
/
,
'
/
/
^
1
1
1
1
1
^•-*
,
© ©
NOX
Dust
S02
Measuring Point
Fig. 3.8 Basic System for Emission Control
Multiple Hearth Furnace
Furnace ^ —
«• Cooling \-» GaS(A,b,?'y
)tion\_L Minutely Dust N. ^
) | Collector T~^
Deodorization N
Fluidized Bed Furnace ~l
Furnace \— •-
Recovery \ Dry Dust \ __
of Heat p^ Collector j~*
Cooling \_.» Gas Absorpt\
PT ion (Alkali)
y. Minutely DusK
Collector
160
-------
Table 3.19 Standard Requirement of Emission Control Equipment for Two Different Furnaces
Heat Recovery
Dry Type Dust
Collector
Cooling
Absorption
Minutely Dust
Collection
De-odorization
Multiple Hearth Furnace
Stack gas temperature ranges from 150~
300°C. It is too low to recover the heat.
Ash is disposed from bottom pit. Dust
concentration in stack gas is as low as 1~
3 g/N-m3 and, no dust removal is required,
unless wet scrubber follow.
Fluidized Bed Furnace
Stack gas temperature ranges from 800 to
900°C. Excess heat above 300°C can be
recovered.
All ash is included in stack gas. Dry type
dust collector is required to reduce load for
wet type scrubber.
Cooling is required as pretreatment in advance to absorption or minute dust collection.
SOx, HC1 and C12 should be removed through absorption process.
Fine particle material should be removed to attain such a low concentration as 0.05 g/N-m3
Deodoring is required.
Operation temperature is high enough to
decompose all smelling material. No de-
odoring equipment is required.
In the next stage, the absorption and removal of SOx, HC1, chlorine (C12) and
other acidic gases conducted by washing with chemical. The SOx level at the incin-
erator outlet is normally 20 to 500 ppm. Not all of the sulfur compounds in the
dewatered cake is transfered into the emission gas, some 50 to 80% remains in the
ash. This is because of the presence on non-combustible sulfates (like CaSO4 and
BaSO4) etc. in the dewatered cake, and because of the likely reaction between SOx
(produced during incineration) and alkaline components in the ash. Previous surveys
found that water washing removed large proportions of SOx, but to meet stringent
emission standard, caustic soda (NaOH) washing needs to adopt. But since dust
still remain in the gas at this stage, and higher pH levels, although reducing the SOx
level in the emission induce, the caustic soda to react with the CO2 in the gas emis-
sion, the pH is regulated to about 7 to 8, employing a recycling method. Excessive
consumption of NaOH, and blockage of filter due to the dust, are thus avoided.
HC1 and C12 are also removed in the same process, HC1 being sufficiently reduced
by water or alkaline solution washings, and C12 absorbed by the alkaline solution.
Most of the dust is removed by cooling and absorption, these processes reduc-
ing the concentration down to about 0.2 to 0.5 g/Nm3. However, these processes
are not very efficient in removing the very fine particles which diameter are less than
10/;. Low pressure difference mechanical dust collector (Cyclon) are not very
efficient either, but fine dust collector (electric dust precipitator etc.) can bring the
level down to about 0.05 g/Nm3.
The dilution ratios in odor measurements under normal conditions varied con-
siderably from 70 to 20,000. Although after burning is used to remove offensive
odor, this process consumes large amounts of fuel. Therefore heat recovery is
necessary. Chemical washings with acid and alkalis are also reasonably efficient in
reducing offensive odor, but they cannot achieve complete removal.
Concentration of nitrogen oxides (NOx) is normally about 30 to 150 ppm, and
this is considered to be due to "fuel NOx" rather than "thermal NOx". The amount
161
-------
of nitrogen in the volatile matter of sewage sludge is 4 to 8% (by weight), 1 to 4% of
which forms NOx. At the moment, however, there is no NOx emission control
standards for sewage sludge incineration.
The emission gas temperature at the incinerator outlet in fluidized bed inciner-
ators is 800 to 900°C, thus possible heat recovery up to about 300 to 350°C. How-
ever, since all the incineration ash is theoretically carried by the emission gas, special
care must be exerted to prevent blockage in the heat exchanger.
The quantity of dust varies considerably according to the condition of the
incinerated sewage sludge (ash contents), but normal concentration is from 30 to
160 g/Nm3. Therefore, a dry-type dust collection is adopted (mechanical scrubber)
after the heat exchanger, and this in turn is followed by a wet washing to further
reduce the dust.
Furthermore, the area of contact between the sewage sludge and gas in the
fludiged bed incinerator is relatively large, so when the internal temperature is
maintained at 80o to 900°C, and lime used as a coagulant, a certain amount of reac-
tion between the lime and SOx, HC1, and C12 can be expected. The source and
mechanism of the generation process of pollutants in gas is essentially the same as in
the multiple furnace, so, the emission control system are composed with dry type
dust collection.
By combustion and decomposition of offensive odor substances in the inciner-
ator, there are no odor substances left in the emission gas, so no deodoring devices
are required.
It has been believed that generation of NOx by fluidized bed incinerator had
been higher than in multiple furnace, but the results of this survey show that this
was not exact. There is no emission standard of NOx which is applicable to sludge
combustion incinerator at the present.
162
-------
CHAPTER 4. STUDIES ON SEWAGE SLUDGE PYROLYSIS
4.1 Introduction 164
4.2 Pilot Plants and Sludge Cakes Used in Experiment 165
4.3 Basic Study on Drying-Pyrolysis Process 169
4.3.1 Experiments of Drying for Dewatered Cake Using by Indirect
Steam Dryer 169
4.3.2 Experiment on Pyrolysis of Dried Cakes 171
4.3.3 Products of Dried Cake Pyrolysis 179
4.4 Practical Study on Drying-Pyrolysis Process 182
4.4.1 Experiment on Drying for Dewatered Cakes Using by Indirect
Steam Dryer 182
4.4.2 Experiment on Pyrolysis 182
4.4.3 Products of Dried Cake Pyrolysis 186
4.4.4 Comparison of Drying-Pyrolysis Process, Direct Pyrolysis Process
and Indirect Pyrolysis Process 190
4.5 Summary 192
163
-------
4. STUDIES ON SEWAGE SLUDGE PYROLYSIS
4.1 INTRODUCTION
Sewage treatment plants in large municipalities and their environs are being
subjected to increasing restrictions on the acquisition of land for sewage sludge land-
fill in Japan. For this reason, there are found many cases where sludge is incinerated
at sewage treatment plant sites for the most effective use of the land acquired to
their sludge filling.
However, the incineration of sewage sludge has been faced with several severe
problems, which require an early settlement.
First, the more severe environmental quality standard on air pollution has
established it indispensable for sewage treatment plants to set up incidental facilities
of incinerators, such as electric precipitators, to prevent pollution causing by the
exhaust gas. The construction and operation of such facilities require additional
expenses.
Second, it has also become necessary to set up incidental facilities of
incinerators for offensive odor control, such as exhaust gas combustion (after-
burning) facilities, because of the strong demand from residents for preventing
offensive odor arising from sludge incineration. The construction and operation of
such facilities also require additional expenses.
Third, it has been found that lime used as a conditioner of sludge dewatering,
and trivalent chromium compounds contained in municipal sewage sludge show a
chemical reaction in the furnace at the time of incineration. The trivalent chromium
compounds in sludge are oxidized into hexavalent chromium compounds which are
soluble in water. Therefore, the filling of land with incinerated ash has a danger of
causing the pollution of surface water and underground water by hexavalent
chromium compounds. For the prevention of such pollution, it requires much
expense for landfill.
Fourth, the operational cost for sludge incineration — fuel cost and electric
power charge — has been increasing sharply every year due to the spirals in the prices
of oil products in addition to the increased use of fuel and electric power for in-
cidental facilities of incinerators. Sewage treatment plants in some areas are obliged
to use better quality fuel than before to establish the environmental quality standard
on air pollution.
Under these circumstances, it is expected to be more advantageous, for the
following reasons, to reduce the volume of solid residue (ash) by pyrolysis than to
incinerate it.
i) In pyrolysis, the furnace is operated naturally at the lower combustion air ratio
than in incineration. Accordingly, the amount of exhaust gas is reduced and the
construction cost and the operation cost (fuel cost and electric power charges) of
the incidental facilities for the control of both air pollution and offensive odor
164
-------
might be able to cut down.
ii) Since the inside of the pyrolysis furnace is maintained in a reducing condition
or in a condition close to it, there is little possibility of the trivalent chromium com-
pounds in sewage sludge being oxidized into haxavalent chromium compounds.
iii) Pyrolysis might require more fuel in the furnace itself than incineration. How-
ever, the amount of fuel used in the furnace might be able to reduce, if combustible
gas obtained by pyrolysis is burned in the combustion chamber and steam generated
in boiler is used for preliminary drying of sludge. Therefore, there is expected a
strong possibility that fuel consumption for the pyrolysis as a whole system could be
smaller than that for incineration.
So far, multi-hearth furnace have dominantly been used for sewage sludge in-
cinerations at sewage treatment plants in Japan. Therefore, there are many skillful
engineers and operators for design and operation of such furnaces. If the multi-
hearth furnaces now in use are rebuilt for pyrolysis of sewage sludge, it will be
expected of great benefit to the social and economical aspects in the nation.
For these reasons, the Ministry of Construction decided on the disbursement of
the public works technology and development subsidy for fiscal 1976 to conduct
practical study work on pyrolysis by applications of multi-hearth furnace. The
ministry offered for public subscription to interesting organizations and, after
screening application documents, decided to give the subsidy to a privated firm
(NGK Insulators, Ltd., Nagoya). The company, which has experiences of basic
study works in the past (1), proposed to conduct additional basic study and new
practical study at pilot plants. The Ministry of Construction organized a discussion
group to have the views of users reflected on the study. The group is made some
engineers of Kyoto University, Osaka Prefecture, Kyoto City, Hyogo Prefecture and
the Japan Sewage Works Agency as well as the Ministry of Construction.
The Practical study was not completed at the time of this reporting. However,
a series of experiments were concluded and their results were compiled. They were
conducted at a pilot plant established in the Kawamata Sewage Treatment Plant site
of Osaka Prefecture, using raw dewatered sludge carried from the Toba Sewage
Treatment Plant in Kyoto. At present, the project is being examined from the
economic viewpoint, and conditions for the designing of facility to be put to
practical use are being discussed.
More experiments are to be conducted at the pilot plant, using heat-treated
sludge taken from a sewage treatment plant in Osaka Prefecture and raw dewatered
sludge separated from waste at a chromic tanning pre-treatment facility in Hyogo
Prefecture.
4.2 PILOT PLANTS AND SLUDGE CAKES USED IN EXPERIMENTS
Basic study and practical study were conducted separately at different pilot
plants. Used in the basic experiments was a pilot plant with a capacity to treat 2
tons of sludge cakes per day with the water content of 75% The flow chart of
this pilot plant is shown in Fig. 4.1. The Figure shows the sampling points for
solid (Si - Ss), liquid (Li - Ls) and gas (Gi - Gs) in addition to various sorts
of machinery and instrumentation constituting the pilot plant.
165
-------
Fig. 4.1 Pilot Plant Flow Chart Used for Basic Study
Fuel Supply
Industrial
Water Supply
Explanation
©
©
CD
©
©
Cake
feeder
Paddle
dryer
Single-
hearth
furnace
De-
humidtfer
Blower
for dryer
©
©
©
©
©
Burner
Combustion
chamber
Blower for
partial
combustion
Blower for
exhaust gas
Scrubber
stuck
©
©
©
©
©
Blower for
combustion
chamber
Blower for
circulated
gas
Blower for
burner
Fuel tank
Fuel pump
©
©
@
@
©
Heat
source
chamber
Nitrogen
gas supply
Water
softening
installation
Soft water
storage
tank
Water
supply
pump
®
®
©
®
©
Exhaust gas
boiler
Condensed
water tank
Condensed
water
circulator
Solid residue
cooling tank
and container
Screw type
feeder
®
©
(28)
®
@*
Conveyer
Hoist
Cake
container
Double
sealing
damper
Dried
cake
container
Sampling point
Sampling point of solids
S, Cake of dryer inlet
S2 Cake of dryer outlet
S3 Residue of pyrolysis
Sampling point of liquids
L, Supplied water
L2 Wastewater of dehumidifer
L, Wastewater of scrubber
Sampling point of gases
G, Outlet of dryer
Gj Outlet of pyrolysis furnace
G3 Inlet of combustion chamber
G4 Outlet of exhaust gas boiler
G, Outlet of scrubber
The flow chart of the pilot plant used for practical study is shown in Fig. 4.2.
It is different from the pilot plant for the basic study in the following points.
i) The indirect steam dryer of paddle type was changed from a two-shaft dryer
to a four-shaft dryer.
ii) The plant was designed so that dewatered sludge cakes could also be thrown
into the furnace directly without passing through the indirect steam dryer of paddle
type.
iii) The single-hearth furnace was changed to a four-hearth furnace.
iv) The heat source chamber was directly attached to the pyrolysis furnace in
166
-------
Fig. 4.2 Pilot Plant Flow Chart Used for Practical Study
Water Supply
Secondary
~j—I Effluent Supply
Explanation
©
@
0)
0
©
©
©
®
Cake container
Hoist
Cake feeder
Dried cake
feeder
No. 1 cake
conveyer
No. 2 cake
conveyer
No. 3 cake
conveyer
No. 1 screw
conveyer
No. 2 screw
conveyer
Paddle dryer
©
©
®
@
(15)
V^-y
©
(rf>
(LJ)
©
®
Sieve machine
Dried cake con-
veyer
Dried cake con-
tainer
Roller conveyer
Pyrolysis fur-
nace
Ignition burner
for partial com-
bustion
Heat source
chamber
Heat source
burner
Blower for
burner
Propane gas
supply
®
©
©
@
(25)
^y
©
6^1
^5
©
©
Fuel tank
Fuel pump
Compressor
Quenching
tank
Residue carry
conveyer
Residue con-
tainer
Roller con-
veyer
Blower for
pyrolysis
No. 3 scrubber
No. 2 blower
for exhaust gas
©
©
©
(34)
(P)
"Cx
(36)
(T7)
^
/^
Vi3'
(39)
®
No. 1 scrubber
Blower for
dryer
Combustion
chamber
Burner fpr
combustion
chamber
Blower fpr
combustion
chamber
Boiler
Condensed
water tank
Condensed
water circulator
Soft water
tank
Water soften-
ing installation
©
©
©
@
(45)
VJx
@
(4^
($1)
Water supply
tank
No. 2 water
supply pump
No. 1 blower
for exhaust gas
Blower for cir-
culation
No. 2 scrubber
Water storage
tank
No. 1 water
supply pump
Sampling point
Sampling point of solids
S, Cake of dryer inlet
Sa Cake of dryer outlet
S3 Residue of pyrolysis furnace
Sampling point of liquids
L, Supplied water
L2 Wastewater of No. 1 scrubber
L3 Wastewater of No. 2 scrubber
Sampling point of gases
G, Outlet of dryer
G2 Outlet of heat source chamber
G3 Outlet of pyrolysis furnace
G4 Outlet of combustion chamber
G, Outlet of scrubber
order to reduce heat loss.
v) The pilot plant was designed so that experiments could be conducted with the
drying-pyrolysis process as a continuous system.
vi) The system to deal with solid residue discharged from the furnace was changed
so that it would drop into water to be scooped up automatically.
vii) A propane gas burner was attached to each hearth of the pyrolysis furnace as a
supplemental heat source.
167
-------
viii) The combustion chamber was designed to allow the automatic control of
oxygen concentration in it.
Table 4.1 shows the details of main machinery and instrumentation of the pilot
plants both for basic study and for practical study.
Table 4.1 Details of Pilot Plant
Name
Indirect
Steam
Dryer
Pyrolysis
Furnace
Heat
Source
Chamber
Com-
bustion
Chamber
Exhaust
Gas
Boiler
Items
Type
Numbers of Shaft
Areas of Total Heat Transfer
Numbers of Screw per Shaft
Dimension (mm)
Revolution of Shaft
Counter of Drain
Method of Heating
Type
Total Bed Areas
Dimension (mm)
Attachment
Capacity of Burner
Dimension (mm)
Duct Length to Pyrolysis
Furnace
Attachment
Type
Capacity of Burner
Volume of Chamber
Dimension (mm)
Type
Areas of Total Heat Transfer
Production of Steam
Max. Pressure of Steam
Drain Storage Tank
Drain Circulator
Soft Water Tank
Softening Water Installation
Water Supply Pump
Pilot Plant for Basic Study
Paddle Type
2
8.1m2
16
560 Wx 850 H x 2,800 L
12rpm
Volumetric
Inner Heating
Single-Hearth Furnace
2.1 m2
1,800 ID x 2,200 OD x 1,000 H
-
90,000 kcal/hr
400IDx8000Dx 1.500L
4 m
Circulating Gas Flow Control
Unit
Direct Combustion
90,000 kcal/hr
0.2m3
400 ID x 800 OD x 1.500L
Breeching 3 Pass
7.7m2
100kg/hr
7 kg/cm2 • G
0.25 m3
0.03 m3
0.2 m3
200 kg/hr
6602/hrx80mH
Pilot Plant for Practical Study
Paddle Type
4
10.1m2
12
1,097 Wx 1.125H x 2,300 L
15 rpm
Volumetric
Inner Heating
4-Hearth Furnace
1.63m2
900 ID x l,3600Dx 2,096 H
Gas Burner 5,000 kcal/hr x 3
80,000 kcal/hr
250 ID x 760ODx720L
0.5 m
Circulating Gas Flow Control
Unit
Direct Combustion
150,000 kcal/hr
0.25 m3
400 ID x 800 ODx 2,412 L
Breeching 3 Pass
5.8m2
100 kg/hr
9.5 kg/cm* -G
0.33m3
0.038m3
0.2m3
200 kg/hr
2002/hrx 10 kg/cm2
The dewatered cakes used in the experiments were taken from the vacuum
filter room of the Toba Sewage Treatment Plant in Kyoto City. Table 4.2 shows the
analytical results of dewatered cake samples. The compositions of ignition loss of
the dewatered cake samples are shown in Table 4.3. The analytical results of the
perfect ash in the dewatered cake samples are also shown in Table 4.4.
168
-------
4.3 BASIC STUDY ON DRYING-PYROLYSIS PROCESS
4.3.1 EXPERIMENTS OF DRYING FOR DEWATERED CAKE USING BY
INDIRECT STEAM DRYER
The dryer used in the experiments is an indirect steam dryer of paddle type
shown in Fig. 4.3. Steam used for the dryer is supplied by the exhaust gas boiler
(21). That is, after the pressure of steam is adjusted so that steam temperature will
reach a fixed point, the steam is supplied to the jacket, screw and shaft of the dryer,
as shown in Fig. 4.3. And, the steam is condensed into moisture after being used for
drying dewatered cakes. The moisture was returned to the exhaust gas boiler after
volumetric measurement. In the experiments, the Overall Heat Transfer Coefficient
(U) was found by Equation-( 1).
U = Q/A-At (Kcal/m2 -hr^C) (1)
Where, At = ts - tc
Q = Ys x Md
Q Heat Transfer Capacity (Kcal/hr)
A Total Heat Transfer Area of the Dryer (m2)
ts Temperature of Supplied Steam (°C)
tc Average Temperature of Dewatered Cakes in the Dryer (°C)
Md Amount of Condensed Moisture Generated (kg/hr)
Ys Condensed Heat of Supplied Steam (Kcal/kg)
Some examples of relationship between the moisture content (%) of raw sludge
cakes at the inlet of the dryer and the Overall Heat Transfer Coefficient (U) is shown
in Fig. 4.4. There was no major difference in drying efficiency between raw sludge
and digested sludge, and their Overall Heat Transfer Coefficients (U) are within the
range of 70 ~ 100 Kcal/m2-hr-°C. Similar experiments on heat-treated sludge
showed that its Overall Heat Transfer Coefficient (U) was 215 Kcal/m2 -hr-°C. This
is presumably because the fullness ratio of heat-treated sludge in the dryer is higher
than that of raw sludge or digested sludge and because moisture contents in de-
watered cakes exists in different conditions.
Fig. 4.3 Schematic Drawing of the Indirect Steam Dryer of Paddle Type
Used for Pre-Treatment of Sludge Cake
Dewatered sludge
cake Screw
Air
—•• Exhaust gas
c
169
-------
Fig. 4.4 Relationship between Moisture Content and
Overall Heat Transfer Coefficient
250
200
150
s
o 100
50 -
100:250
40
50
60
100:0
i Dried and wet mixed
raw sludge cake
o Raw Sludge cake
X Digested sludge cake
A Heat treated sludge cake
D Tannery waste sludge cake
Mixture ratio
Wet cake : Dried cake
70 80
Moisture content of cake (%)
Table 4.2 Analytical Result of Dewatered Cake Samples
(Dry Base)
Date
of
Sam-
pling
Aug.
9
Aug.
30
Date
of
Sam-
pling
Aug.
9
Aug.
30
Mois-
ture
Con-
tent
(%)
74.6
75.6
Pb
(ppm)
100
175
Igni-
tion
(%)
55.0
49.3
As
(ppm)
4.4
Vola-
tile
Con-
tent
(%)
53.2
52.0
Total
Cr
(Ppm)
200
170
Gross
Calo-
rific
Value
(kcal/
kg-DS)
2,470
1,800
Cr+6
(ppm)
-
7.3
C
(%)
24.8
18.0
H
(%)
4.1
4.0
Zn
(ppm)
2,600
1,450
N
(%)
2.8
2.9
Cu
(ppm)
-
360
S
(%)
0.71
0.51
Fe
(ppm)
-
6.21
0
(%)
25.2
30
A1303
(%)
4.8
2.17
Cl
(%)
-
1.0
CaO
(%)
14.08
26.3
CN
(ppm)
-
4
MgO
(%)
-
0.77
NH3
(ppm)
-
220
Na3O
(%)
-
0.18
Hg
(ppm)
-
1.7
K,0
(%)
0.49
-
Cd
(ppm)
-
7.2
SO,
(%)
13.88
7.98
170
-------
Table 4.3 Compositions of Ignition Loss in Samples
Date of
Sampling
Aug. 9
Aug. 30
Gross
Calorific
Value
(kcal/kg-DS)
4,491
3,651
C
(%)
45.1
36.5
H
(%)
7.5
8.1
N
(%)
5.1
5.9
S
(%)
1.3
1.0
0
(%)
45.8
60.9
Cl
(%)
-
2.4
CN
(ppm)
-
8.1
NH3
(ppm)
—
446
Table 4.4 Analytical Result of Perfect Ash in Samples
Date of
Sampling
Aug. 9
Aug. 30
Total
Cr
(T-Cr)
(ppm)
360
355
Cr+6
(ppm)
82
190
Cr+6/T-Cr
(%)
17.2
53.5
Soluble
Cr+6
(S-Cr+6)
(mg/8)
4.5
0.36
Soluble Rate of Cr+6
(%)
S-Cr+6
T-Cr+6
(%)
72.6
1.9
S-Cr+6
T-Cr
(%)
22.5
1.0
CaO
(%)
31.3
51.9
4.3.2 EXPERIMENTS ON PYROLYSIS OF DRIED CAKES
In the experiments, dried cakes by the indirect steam dryer were stored in the
feeder at first and then a constant amount of them was fed into the single-hearth
furnace(s) by a screw feeder (2^) shown in Fig. 4.1. The heat sources to the furnace
were hot blast from the hot source chamber and heat of partial combustion propor-
tionate to the ratio of fixed combustion air to sludge feed to furnace. Gas from the
outlet of the furnace was sent to the combustion chamber(v), where combustibles
was burned and such offensive odor components, HCN and NH3 were decomposed,
and then the heat was recovered as steam by the waste heat boiler(2J). Part of the
exhaust gas in the boiler was circulated to adjust hot blast in which oxygen con-
centration is almost zero.
The remainder of the waste gas was released into the air after being sent
through the scrubber (To). The solid residue taken out of the pyrolysis furnace was
cooled indirectly without contact with the air.
The conditions of these experiments were as follows.
i) Ratio of theoretical amount of combustion air to actual amount of combus-
tion air of fed sludge: 0 ~ 2.0
ii) Temperature in pyrolysis furnace: 600 ~ 900°C.
iii) Sludge feed loading into furnace: 10 ~ 40 kg- DS/m2 • hr
iv) Estimated detention time of sludge in furnace: 15 ~ 60 min.
v) Condition of decomposition of exhaust gas
Temperature in combustion chamber: 900 ~ 1,100°C
Oxygen concentration: 0 ~ 3%
The ratio of theoretical amount of combustion air to actual amount of
combustion air of fed sludge (ratio of amount of combustion air) was adjusted
by a partial combustion blower.
171
-------
In order to evaluate the degree of decomposition of combustibles, the igni-
tion loss of solid residue was measured and the decomposition rate of combustibles
was estimated by Equation (2).
Decomposition Rate of Combustibles (^
Ignition Loss of Solid Residue (%)
100 - Ignition Loss of Solid Residue (ty
_._ Ignition Loss of Fed Cake(%)
' 100 - Ignition Loss of Fed Cake (%)
a. Ratio of Theoretical Amount of Combustion Air to Actual Amount of
Combustion Air of Fed Sludge (Ratio of Amount of Combustion Air)
Three sorts of data were collected to investigate this problem. The first con-
cerned the changes in the form of chromium in solid residue according to the ratio
of amount of combustion air, which are shown in Fig. 4.5 and Fig. 4.6. Fig. 4.5
shows the results of experiments on raw sludge at the Toba Sewage Treatment Plant.
Fig. 4.6 shows, for comparison, the results of experiments on sludge of chromium
tanneries' waste which contained a large amount of trivalent chromium compounds.
The second data concerned the relationship between the ratio of amount of com-
bustion air and both ignition loss of solid residue and the decomposition rate for
combustibles in sludge. It is shown in Fig. 4.7.
Fig. 4.5 and Fig. 4.6 show that, when the ratio of amount of combustion air is
below 1.0, the ratio of Cr+6/T-Cr in solid residue is smaller than that of Cr+6/T-Cr
in dewatered cake and that the lower the ratio of amount of combustion air, the
higher is the decrease rate. Elution of hexavalent chromium from the solid residue
was not observed. If the ratio of amount of combustion air is below 1.0, oxygen
supplied to the pyrolysis furnace is consumed by the combustion of inflammable gas
generated by pyrolysis and the combustion of carbon retained in solid residue, with-
out causing the oxidization of new trivalent chromium compounds. In case the ratio
of amount of combustion air is still lower, a part of the hexavalent chromium com-
pounds already contained in sludge is reduced in the pyrolysis furnace by reducing
gas, such as hydrogen and carbon oxide gases generated by pyrolysis.
In contrast, the ratio of Cr+6/T-Cr were fairly increased in solid residues when
dewatered cake was dried and incinerated completely in an electric furnace and
when it was incinerated at the furnace of pilot plant with the ratio of amount of
combustion air set at 2.0, comparing to the ratio of Cr+6/T-Cr in dewatered cake
itself. When the amount of the hexavalent chromium compounds eluted was
measured by the Solubility Test Method as provided by the Ministerial Ordinance of
the Prime Minister's Office, it has been found at some plants that the soluble con-
centrations of hexavalent chromium in solid residue exceed the limit of 1.5 rng/C
sometimes, when dewatered cakes were incinerated in existing furnaces. This means
that a high ratio of amount of combustion air, such as about 2.0, promotes the
oxidization reaction of trivalent chromium compounds and a part of them changes
hexavalent chromium compounds.
According to Fig. 4.7, the higher the ratio of amount of combustion air, the
further promoted is the decomposition of combustibles in sludge. This means that
172
-------
a high ratio of amount of combustion air promotes the combustion of carbon re-
maining in solid residue.
From the viewpoint of preventing the oxidization of trivalent chromium com-
pounds in sludge, the appropriate ratio of amount of combustion air is considered to
be around 0.5 ~ 0.7.
Fig. 4.5 Behaviour of Chromium in Each Solid Residue
(Raw Sewage Sludge in Toba Sewage Treatment Plant)
100
B
u
o
c
o
U
10
(Oxygen concentrations
at outlet of furnace are
shown in parenthesis)
(0.7%)
(0.5%)
Cr
+6
^
\
\
\
— o—
(ND)
/
(4.5 mg/fi)
D
XX(0.87mg/8)
(ND)
(Soluble concentration of
hexavalent chromium in
solid residue are shwon in
parenthesis)
_L
10
-------
Fig. 4.6 Behaviour of Chromium in Each Solid Residue
(Raw Sludge of Tanneries Waste)
10,000
1,000
bfl
u
<*-<
o
a
o
U
°"(124mg/fi)
(Oxygen concentrations at
outlet of furnace are
shown in parenthesis)
(0.27)
100
10
(l,440mg/B)
10
(Soluble concentrations of
hexavalent chromium in
solid residue are shown in
parenthesis)
Dried 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Perfect
cake Ash
Ratio of amount of combustion ail
V
0.1
0.01
174
-------
Fig. 4.7 Variation of Both Ignition Loss of Solid Residue
and Decomposition Rate of Combustible to Ratio
of Amount of Combustion Air
g
£
e
0
1
0
ex
1
•§
3
C
O
'H
100
90
80
70
60
50
40
30
20
10
n
.
-_.——• * ""— "~ Decomposition rate of co
Pyrolyzing temp.
Feed loading of c
-
-
•• — ».. Ignition loss of solid r
1 1 1 1 , , , | -
0.4 0.6 0.8 1.0
1.2 1.4 1.6 1.8 2.0
Ratio of amount of combustion air
b. Pyrolyzing Temperature
Changes in pyrolyzing temperatures, ignition loss of solid residue and the rate
of decomposition of comsustibles are shown in Fig. 4.8. The Figures are given for
pyrolysis when the ratio of amount of combustion air was 0.6 and 0. There is a
tendency that the higher the pyrolyzing temperature, the higher is the decomposi-
tion rate of combustibles and the lower is the ignition loss of solid residue. At the
pyrolyzing temperature of 900° C, the decomposition of combustibles was almost
completed. When the ratio of amount of combustion air was 0, the decomposition
rate tended to drop by about 5%, compared with pyrolysis when the ratio of amount
of combustion air was 0.6.
Shown in Fig. 4.9 is the relationship between pyrolyzing temperatures and the
rates of carbon, hydrogen and nitrogen remaining in solid residue. When the
pyrolyzing temperature was over 800°C, most of the ignition loss of solid residue
was carbon. There is a difference of more than 5% in carbon content in solid residue
between pyrolysis when the ratio of amount of combustion air was 0 and when the
ratio was 0.6. There was also a slight difference each in the nitrogen and hydrogen
contents in solid residue according to the differences in the ratio of amount of com-
bustion air at 0 and 0.6.
c. Feed Loading of Dried Cake
Experiments were conducted on changing feed loading of dried cake (unit:
kg-DS/m2-hr) with the pyrolyzing temperature set at 900° C and the ratio of
175
-------
amount of combustion air at 0.6. Fig. 4.10 shows the changes in the ignition loss of
solid residue and the rate of decomposition of combustibles caused by changes in
feed loading of dried cake.
With the increase in the feed loading of dried cake, the ignition loss of solid
residue goes up. If the ignition loss of solid residue is to be allowed at about 10%
when filling land with solid residue, the adequate feed loading of dried cake is about
25kg-DS/m2-hr.
d. Detention Time of Dried Cake in Pyrolysis Furnace
Fig. 4.11 shows the relationship between the detention time of dried cake in
pyrolysis furnace and both ignition loss of solid residue and the rate of decompose
tion of combustibles. Details are not clear because the data of experiments are for
the detention time of 15 min. and 60 min. only. Estimating from the Figure,
however, the detention time of at least 45 minutes seems to be necessary to main-
tain the operating condition of ignition loss of solid residue below 10%.
e. Recombustion of Exhaust Gas
Experiments were conducted to grasp the operating conditions of recombus-
tion of exhaust gas from the pyrolysis furnace in order to burn and decompose
pollutants in the gas (HCN, NHs). As a result, it became known that, when Oz
concentration is over 1%, HCN gas can be decomposed almost completely at the
combustion temperature of over 900°C and NH3 gas at over 1,000°C.
Fig. 4.8 Variation of Both Ignition Loss of Solid Residue
and Decomposition Rate to Pyrolyzing Temperature
100
90
80
70
60
50
40 \-
30
20
10
0
Decomposition rate of
combustible
Ratio of amount of
combustion air '=. 0.6
Ratio of amount of
combustion aii = 0
Feed loading of dried cake = 10 kg-DS/m2 -hr
Ignition loss of solid residue
Ratio of amount of
combustion air = 0
Ratio of amount of
combustion air = 0.6
600
700 800 900
Pyrolyzing temperature (°C)
176
-------
Fig. 4.9 Variation of Carbon, Nitrogen and Hydrogen in
Solid Residue to Pyrolyzing Temperature and
Ratio of Amount of Combustion Air
30
u
I
u
n
2
"o
20
10
Carbon
Ratio of amount of
combustion air % 0
600 700 800 900
Pyrolyzing temperature (°C)
-------
Fig. 4.10 Variation of Both Ignition Loss of Solid Residue
and Decomposition Rate to Feed Loading of Dried Cake
100 r
90
80
» 70
.2 60
o
p.
o
50
S 40
30
£? 20
10
Decomposition
rate of combustible
Ignition loss of
solid residue
10 20 30 40
Feed loading of dried cake (kg • DS/m2 • hr)
Fig. 4.11 Variation of Both Ignition Loss of Solid Residue
and Decomposition Rate of Combustible to
Detention Time in Pyrolysis Furnace
i
u
rt
e
.0
Jcomposi
•u
o
WJ
_o
c
.2
'c
bo
100
90
80
70
60
50
40
30
20
10
0
~
__ — *
Decomposition rate of combustible
-
-
-
Ignition loss of solid residue
— _ — 1_ i i |
15 30 45 60
Detention time in pyrolysis furnace (min.)
178
-------
4.3.3 PRODUCTS OF DRIED CAKE PYROLYSIS
a. Remaining Rate of Each Element in Solid Residue
Table 4.5 shows the ratios of various elements remaining in solid residue to
sludge cake. It also shows three operating conditions of pyrolysis and, for corn-
Table 4.5 Remaining Rate of Each Component in Solid Residue
Run
No.
1
2
3
4
Pyroly-
zing
Temp.
(°C)
765-
800
80S-
825
880-
910
795-
835
Ratio
Amount
of
Com-
bustion
Air
0
0.67
0.75-
0.77
2.89
Igni-
tion
Loss
(%)
23.6
10.2
2.8
4.8
Gross
(%)
14.4
9.1
0.9
0
C
(%)
30.4
20.3
3.8
4.1
H
(%)
6.6
4.4
3.9
4.0
N
(%)
9.5
3.0
0.5
0
S
(%)
95.5
115.6
86.7
99.6
0
(%)
39.5
25.5
12.1
13.6
Cl
(%)
65.4
67.5
62.2
58.4
Hg
(%)
<1.5
<1.7
<1.5
<1.5
As
(%)
68.5
77.7
68.5
54.2
Cd
(%)
32.9
28.7
27.4
31.7
Pb
(%)
67.7
53.9
27.6
33.3
Zn
(%)
90.8
113.8
95.0
84.3
Cu
(%)
102.4
125.1
93.2
85.4
Ft
(%)
95.4
82.4
96.3
97.5
T-Cr
(%)
100.7
135.2
97.9
90.6
parison, remaining rate of each element in solid residue.
The higher the pyrolyzing temperature and the ratio of amount of combustion
air, the smaller becomes the ignition loss, thus decreasing the calorific value of solid
residue. In other words, the solid residue becomes closer to that of incineration.
Analyses of six elements show that, in the case of pyrolysis, the amounts of
carbon, hydrogen, nitrogen and oxygen remaining in solid residue differ, depending
on pyrolyzing temperature and ratio of amount of combustion air, while the
amounts of sulfer and chloride vary widely. Concerning chloride, there was a dif-
ference in amount remaining in solid residue between pyrolysis and incineration.
Pyrolysis tends to vaporize less chloride than incineration.
Concerning such heavy metals as mercury, cadmium and iron, there is hardly
any difference in amount remaining in solid residue between pyrolysis and incinera-
tion. But pyrolysis can slightly reduce the vaporization into the air of arsenic, zinc,
copper and total chromium, compared with incineration. It was also found that the
amount of lead vaporized into the air differs greatly, depending on operating con-
ditions of pyrolysis.
b. Concentration and Particle Size Distribution of Dust
The concentration of dust at the outlet of furnace at the time of pyrolysis was
a range between 0,5 ~ 2.87 g/Nm3, or almost at the same level as the concentration
of dust in incineration. However, most of the dust particles generated by pyrolysis
are more than 20/u in size. A calculation of the efficiency of dust removal by the
scrubber showed that the dust removal rate was a range between 75 ~ 97%.
c. Behavior of Nitrogen in Products
How nitrogen in sludge changes form at the outlet of the furnace as a result of
pyrolysis or incineration is shown in Fig. 4.12(1).
In the case of incineration, most of the nitrogen in sludge is estimated to have
changed into nitrogen gas. In the case of pyrolysis, about 30% of the nitrogen in
sludge exists in the form of ammonia gas, 2 ~ 5%in the form of hydrogen cyanide gas
and 1 ~ 10% remains in solid residue, although the amounts differ, depending on
179
-------
operating conditions. The remainder is estimated to turn into nitrogen gas. At the
pyrolyzing temperature of 900° C, the amount of hydrogen cyanide gas generated by
pyrolysis tended to get larger than at 800° C. These hydrogen cyanide gas and
ammonia gas could be decomposed almost completely, when burned in the combus-
tion chamber at the temperature of 1,000°C and at the oxygen concentration of 1 ~
2% in the chamber.
Fig. 4.12 Bahaviour of Nitrogen, Sulfur and Chloride in Products of Pyrolysis
(1) Behavious of nitrogen in products
100
80
60
40
20
0
-
1
4.8
r35.7
9.5
fS//S
• - I
\\^
5.8
31.5
2
V SS /
^ .
3
1 . O^^2E2
23.9 '•;-
o s| '- -
HCN gas
NH3 gas
Solid residue
(2) Behaviour of sulfur in products
2
100
80
60
§ 40
D
a.
20
0
1
95.5
115.6
3.6
8.9
86.7
99.6
100
80
60
| 40
u
a.
20
0
(3) Behaviour of chloride in products
1
2
21.5
1-65.4
15.0
67.5
33.3
62.2
21.6,
58.4
Condition of experiment
1. T = 765 - 800°C
m = 0
2. T = 805 - 825°C
m = 0.67
3. T = 880~ 910°C
m = 0.75 - 0.77
4. T = 795 - 835
m = 2.89
H:Sgas
SOX gas
Solid residue
T: Pyrolyzing temperature
m: Ratio of amount of com-
bustion air
HC1 gas
Solid residue
180
-------
d. Behavior of Sulfer in Products
How sulfer in sludge changes form by pyrolysis or incineration is shown in
Fig. 4.12(2). With the exception of No.3 as shown by the Figure, the sulfer in
sludge all remained in solid residue. In the case of incineration (No. 4), too, all the
sulfer in sludge remained in solid residue.
Of the data shown in Fig. 4.12(2), No.3 shows an efficient and economical
operating condition for pyrolysis, under which part of the sulfer in sludge turns into
hydrogen sulfide and SOX. Since hydrogen sulfide turns into SOX when burned in
the combustion chamber at the temperature of about 1,000°C, it is estimated that,
under the operating condition of No. 3, about 12% of the sulfer is considered to
change into SOX.
e. Behavior of Chloride in Products
As shown by Fig. 4.12(3), about 60% of chloride in sludge remains in solid
residue, while part of it is converted into hydrogen chloride. But it was not detected
in the form of chlorine gas.
Compared with pyrolysis, incineration tends to generate a considerably large
amount of hydrogen chloride. In either case, however, the integrated amount of
chloride does not reach 100% and it is not known whether there was a measurement
error or the remainder exists in the form of another compound.
f. Offensive Odor Components in Exhaust Gas
The results of measurement of offensive odor components in dry exhaust gas is
shown in Table 4.6. The measurement was made only on the experiment condition
No. 3 (at the pyrolyzing temperature of 880 ~ 910°C with the ratio of amount of
combustion air set at 0.75 ~ 0.77). Gi in the Table shows the sampling point for
gas at the outlet of dryer, 63 at the outlet of pyrolysis furnace and GA at the outlet
of combustion chamber. Main offensive odor components at Gi are acetaldehyde
and ammonia, and a little amounts of methyl mercaptan, dimethyl disulfide, tri-
methylamine and carbon disulfide were also detected.
The main offensive odor components at Gs are hydrogen sulfide, ammonia and
formaldehyde. A little amounts of carbon disulfide, trimethylamine and acetalde-
hyde were also detected.
Exhaust gas sampled at G4 after gas at Gi and Gs are burned and decomposed
in the combustion chamber does not contain major offensive odor components at
all. Only very small amounts of methyl sulfide, ammonia, acetaldehyde and carbon
disulfide are contained in the exhaust gas.
Table 4.6 Analytical Results of Offensive Odor Component in Exhaust Gas
Run
No.
3
Pyroly-
zing
Temp.
(°C)
880-
910
Ratio of
Amount
ofCom-
bustion
Air
0.75-
0.77
Portion
of
Sam-
pling
GI
G3
G4
H,S
(ppm)
0.02
11
<0.02
Methyl
Mercap-
tan
(ppm)
0.006
<0.006
•C0.006
Methyl
Sulfide
(ppm)
<0.005
<0.002
0.002
Tri-
Methyl-
amine
(ppm)
0.003
0.003
0.001
NHj
(ppm)
0.09
980
0.74
Di-
methyl
Disul-
fide
(ppm)
0.04
<0.001
<0.001
Ster-
ane
(ppm)
<0.02
<0.002
<0.002
Acetal-
dehyde
(ppm)
1.8
0.002
0.007
Form-
alde-
hyde
(ppm)
<0.05
1.1
<0.04
Acetic
Acid
(ppm)
<2
<3
<3
Carbon
Bisul-
fide
(ppm)
0.09
0.15
0.0005
Degree
of
Odor
(Times)
100
25
1
181
-------
g
Washed Waste Quality of Exhaust Gas and Their Countermeasure
The results of analysis of washed waste of dried exhaust gas are shown in
Table 4.7. As shown in the Table, the washed waste contains a little amounts of
zinc, copper and iron in addition to 0.002 ~ 0.006 mg/£ of mercury. The problem
involved in washed waste quality is that of pH. However, it became clear as a result
of experiments for practical study.
Table 4.7 Washed Wastewater Quality Results of Exhaust Gas
Run
No.
1
2
3
4
Pyroly-
zing
Temp.
<°C)
1,050-
1,090
990-
1,050
1,020-
1090
1,060-
1,100
Com-
bustion
Cham-
ber
0,/CO
(Vol %)
1.4/0
1.3/0
1.3-
2.0/0
1.8/0
pH
4.3
4.7
7.1
3.5
BOD
(mg/S)
2
2
2
2
SS
(mg/S)
30
16
17
9
CN-
(mg/C)
<0.01
<0.01
<0.01
0.03
Phenol
Com-
pound
(mg/S)
0.01
0.02
<0.03
<0.03
Hg
(mg/S)
0.004
0.006
0.005
0.002
As
(mg/E)
<0.01
<0.01
<0.01
<0.01
Cd
(mg/f>)
<0.01
<0.01
0.01
<0.01
Pb
(mg/S)
<0.05
0.09
0.05
<0.05
Zn
(mg/S)
0.22
0.19
0.26
0.14
Cu
(mg/S)
0.02
0.02
0.01
0.01
Fe
(mg/S)
7.6
3.2
3.9
3.7
T-Cr
(mg/S)
<0.01
<0.01
<0.01
<0.01
Cr+6
(mg/S)
<0.01
<0.01
<0.01
<0.01
4.4 PRACTICAL STUDY ON DRYING-PYROLYSIS PROCESS
Experiment for practical study were conducted on the basis of the results of
the basic study mentioned in Section 4.3 by using the pilot plant shown in Fig. 4.2.
In the experiments, an indirect steam dryer and a pyrolysis furnace were operated
continuously, and the results of the experiments were compiled. The series of ex-
periments were conducted by changing pyrolyzing temperature and feed loading of
dewatered cake. The results of the experiments are shown in Table 4.8. Run
No. 801 ~ 808 in the Table mean a series of continuous experiments on drying-
pyrolysis process, and Run No. 809 was an experiment to feed into the pyrolysis
furnace dried cakes stocked in the dry cake feeder. Analysis of products was done
only on Run No. 803 and No. 804.
4.4.1 EXPERIMENTS ON DRYING FOR DEWATERED CAKE USING BY
INDIRECT STEAM DRYER
The indirect steam drying of dewatered cakes was carried out more efficiently
than in basic study. Its Overall Heat Transfer Coefficient (U) was 140 ~ 170 Kcal/
m2-hr-°C, which means a sharp rise in efficiency compared with 70 ~ 110 Kcal/
m2 'hr'°C in the basic study.
The paddle type dryer used in the experiments for practical study was a four-
shaft dryer whose mixing frequency is higher than the two-shaft paddle type dryer
used in the basic study. It is presumed that, for this reason, the heat transfer ef-
ficiency was raised.
4.4.2 EXPERIMENTS ON PYROLYSIS
a. Pyrolyzing Temperature
Fig. 4.13 shows the variations in the ignition loss of solid residue and in the
decomposition rate of combustibles, when pyrolyzing temperature was changed
between 700 and 900°C. In the experiments, feed loading of dewatered cake was
182
-------
Table 4.8 Operating Results of Drying — Pyrolysis Process at the Practical Study
Operating
Condition
Samples of
Dewatered
Cake
Indirect
Steam
Dryer
Combustion
Chamber
Exhaust
Gas
Boiler
•Jo.1 Scrub-
bei and De-
humidifier
•Jo.2 Scrub-
ber and De-
humidifier
Pyrolysis
Furnace
Heat
Souice
Chamber
Quality
of Solid
Residue
' — - — — Run No,
Items " _____
Moisture Contents of Cake (96)
Gross Calorific Value (Kcal/kg-DS)
Ignition Loss of Cake
Pressure of Steam Used (kg/cm3 -G)
Temperature of Steam Used (°C)
Feed Rate of Dewatered Cake (kg/hr.)
Moisture Contents of Dried Cake (%)
Amount of Dried Cake Discharge (kg/hr.)
Amount of Vaporized Water (kg-H,O/hr.)
Amount of Condensed Water (kg/hr.)
Shaft and Screw Side (kg/hr.)
Jacket Side (kg/hr.)
Amount of Heat Transfer (Input] (Kcal/hr.)
Overall Heat Transfer Coef. (Kcal/m1 -hr-°C)
Temperature of Combustion Chamber (°C)
Fuel Consumption (B/hr.)
CO/0,
Outlet Temp, of Exhaust Gas Boiler (°C)
Pressure of Boiler (kg/cm] -G)
Amount of Steam Generated (kg/hr.)
Amount of Steam Discharged (kg/hr.)
Flow-rate of Scrubbing Water (ms /hr.)
Temperature at Outlet of Scrubber (°C)
Amount of Exhaust Gas (mj /hr )
Row-rate of Scrubbing Water (m1 /hr.)
Temperature at Outlet of Scrubber (°C)
Feed Rate of Dried Cake (kg/hr.)
Moisture Contents of Dried Cake (%)
Feed Loading of Dried Cake (kg-DS/mJ -hr.)
Amount of Combustion Air SupplytNm1/^.)
Distribution Rate, 1:2:3:4
Ratio of Amount of Combustion Air
Amount of Propane Gas Consumed
Temperature 1st Hearth
2nd Hearth
3rd Hearth
4th Hearth
Detention Time of Dried Cake (mm.)
Static Pressure (mmAq)
o .1 . r- CO H Vol (%)
Outlet Gas <-"£.. Vol.(*>
C,H,,C,H,, Vol. (%)
O3 Vol. (%)
Calorific Value (Kcal/Nm'l
Circulating Gas Temperature (°)
Flow Rate of Circulating Gas (mj /hr.)
Amount of Fuel Consumed (2/hr.)
Amount of Air Supplied (Nm'/hr.)
Temperature in Heat Source Chamber (°C)
Amount of Solid Residue (Drykg/hr.)
Ignition Loss (%)
Decomposition Rate of Combustible (%)
Solved Concentration of Cr+6 (mg/1)
Cr+6 Contents (mg/kg)
(1/rir.)
mp"0" (1/ton-Cake)
801
75.8
2900
59.5
1.6-2.6
128-139
154.1
34.9
57.3
96.8
135
82
53
67,635
176.2
1100-1170
10.3
0/0.4-1.5
204-210
3.6-4.1
204.3
0
3.6-3.9
24-30
35-120
0.8
24-27
57.3
34.9
23.0
83
0:39:44:0
0.77
0.3
465-575
695-720
775-810
705-785
60
+3-+20
0.57.0.12.
0.04
ND.ND,
0.31
24.8
202-210
40
3.5
44
760-890
18.9
20.0
83.0
ND
3.5
14.5
94.2
802
75.8
2900
59.5
2.7-3.8
139-150
203.2
36.3
77.2
126
158
98
60
78,327
168.6
1030-1120
8.6
0/0.9-3.0
208-226
4.3-5.3
2 if. 2
0
2.0-2.1
28-30
50-75
0.8
45-48
77.2
36.3
30.4
80
0:36:44:0
0.56
0.5
770-795
775-840
815-830
790-830
60
+0-+1.2
1 72 0.99
0.42
0.19, ND.
0.27
181.2
208-226
72.4
6.6
75.2
860-940
23.5
152
87.8
ND
4.8
16.5
81.2
803
75.8
2900
59.5
4.5-5.2
155-159
200.1
35.1
74.6
125.5
174
105
69
85,532
142.8
1000-1090
4.8
0/1.2
230-240
6.0-6.5
212.7
0
3.8-3.9
28-32
0.8
42-50
74.6
35.1
29.9
86
0:42:44:0
0.61
0.7
810-885
890-920
910-935
880-920
60
*7~H5
1 34, 1.64,
0.34
0.11, ND,
0.17
139.6
230-240
41.2
8.1
73.5
1030-1100
21.3
8.1
94.0
ND
5.8
14.7
73.7
804
75.8
2900
59.5
3.6-4.5
148-155
182.5
37.1
71.1
113.7
170
103
67
83,881
156.7
1035-1130
5.9
0/1.3
219-235
5.4-6.0
212.8
0
2.8-3.2
27-30
0.8
46-52
71.1
37.1
27.6
86
0:42:44-0
0.66
0.7
870-905
875-920
880-905
890-920
60
-H5-+25
0.95 1.35,
0.24
0.12, ND.
0.26
110.7
219-235
42.2
7.3
65.8
1050-1130
198
8.5
93.7
ND
6.0
14.8
81 3
805
77.5
3140
61.4
1.6-3.4
130-145
101.4
24.7
30.3
71.1
126
75
51
63,000
155.9
960-1055
5.2
0/1.2
190-198
3.2-4.5
210.8
0-20
0.9-2.3
21-31
50-113
0.8
32-55
30.3
24.7
14.1
48.5
0:20:28.5:0
0.68
1.4
890-930
900-930
875-930
860-900
60
+7~t20
1.40, 1.62,
0.34
ND.ND,
0.13
1243
190-198
50
7.3
62.0
1025-1075
8.9
0.9
99.4
ND
3.6
16.1
1594
806
77.5
3140
61.4
4.3-5.2
157
176.1
37.1
63.0
113.1
185.1
1139
72.2
90,884
151.2
1070-1130
8.3
0.1/0.8-1.3
215-225
5.8-6.8
212.5
0
1.2
20-30
0.8
42-52
63.0
37.1
24.4
92
0:46:46:0
0.74
1.0
870-920
885-930
880-920
900-930
60
+2-HO
0.15. 0.37,
ND
ND.ND,
0.53
21.9
215-226
45.1
6.5
58.1
920-990
15.8
3.3
979
ND
2.4
17.4
78.7
807
76.5
3090
59.6
5.1-5.2
150-160
239.0
43.6
99.6
139.4
183
117
66
89,712
146.6
1080-1150
10.2
0/1.2
216-245
5.2-7.0
213.4
0
3.6-3.9
32-35
65-95
0.8
41-59
99.6
436
34.7
108
0:54:54.0
0.62
0.9
795-825
880-915
920-940
870-890
60
-HO-+20
1.72. 1.90,
0.16
1.04, ND.
020
131 4
216-245
323
7.7
54.3
1000-1100
24 7
7.9
94.2
ND
0.9
20.3
84.9
808
76.5
2960
59.5
5.0-5.3
160
256.0
40.4
101.0
155.2
192
119
73
93,982
150.1
1090-1160
9.9
0/0.5-1.2
238-245
7.2-7.6
216.7
0
3.4-3.5
33-36
40-70
0.8
33-36
101.0
404
37.2
128
0:64:64-0
0.72
0.5
805-895
890-920
910-955
880-920
60
•HO-+20
0.57.0.21.
ND
ND, ND.
0.2
23.7
238-245
26.8
7.0
55.0
1085-1190
26 8
9.3
93.0
ND
09
18 2
71.2
809
(77.5)
(3140)
(61.4)
-
-
960-1000
*0
0/2 1
_
-
-
0.8
47-52
103.9
28.8
438
148
0:74:74:0
0.66
0.3
885-920
890-930
880-905
810-925
60
»3~+20
1.11, 1 73,
0.24
ND.ND.
O.I
97.1
186-204
53.6
6.7
59.2
940-1040
31 2
123
91.2
ND
1.7
-
-
Remark: Run No. 809 is Experiment of Pyrolysis Process by Dried Cake Feed.
set at about 30 kg-DS/m2 -hr and the ratio of amount of combustion air at about
0.6. As shown by the Figure, it was found that, if pyrolysis is done at temperatures
of 900°C or more, the ignition loss of solid residue is below 10%.
And Fig. 4.14 shows the relationship between pyrolyzing temperatures and
fuel consumption. Given in the Figure are the fuel consumption in the pyrolysis
furnace alone and the total fuel consumption in the pyrolysis furnace and the
combustion chamber. The amount of fuel consumed in the pyrolysis furnace can be
divided into fuel consumed in the heat source chamber and fuel directly supplied
in the pyrolysis furnace. Propane gas burners were used for direct heating of the
pyrolysis furnace. Listed in the Figure is the amount of fuel which was converted,
on the basis of calorific value, from the amount of propane gas used in the pyrolysis
furnace for direct heating.
183
-------
o
ex
o
o
•8
s
100
90
80
70
60
50
40
30 -
20
10
Fig. 4:13 Variation of Both Ignition Loss of Solid Residue and
Decomposition Rate in Combustible to Pyrolyzing
Temperature
803
801 ^ — —-*""
•— Decomposition rate
in combustible
Numerals show run number of
each experiment in figure
Ratio of amount of combustion air = 0.6
Feed loading of dried cake = 10 kg • DS/m2 • hr
Ignition loss of
solid residue
802
803,804
700 800 900
Pyrolyzing temperature (°C)
Fig. 4.14 Relationship between Pyrolyzing Temperature
and Fuel Consumption
Ratio of amount of combustion air =. 0.6
Feed loading of dried cake = 10 kg • DS/m2 • hr
^
o
i
ed
o
0>
Ctt
C
o
'p!
D.
E
crt
C
o
o
3
b.
180
160
140
120
100
-
Total fuel consumption
s' | Heat source chamber and propane "1
/ for pyrolysis furnace and combustion |
/ 1^ chamber
/
/ Numeral
801 / number
°X. * experim
^^
\. 802 803
80 f- -c „
60
40
20
0
— ^"»»
0
1
/
s show run
of each
ent in figure
80^ ^_ Fuel consumption for pyrolysis
^r-^. . f Heat source chamber and |
-^-*'^***803 1 propane for pyrolysis furnace J
.— - " 802
801
. — i i
700 800 900
Pyrolyzing temperature (°C)
184
-------
Fig. 4.14 shows that, if operation of pyrolysis is carried out at low tempera-
tures, the amount of fuel supplied to the pyrolysis furnace is reduced, but the total
amount of fuel used in the furnace and the combustion chamber tends to increase.
Considering from these results of experiments, it might be said that effective
temperature of the dried cake pyrolysis is at about 900° C.
b. Feed Loading of Dewatered Cake.
In the experiments for practical study, the feed loading of dewatered cake was
changed in the range of 14 ~ 44 kg-DS/m2-hr, while the pyrolyzing temperature
was kept at about 900°C and the ratio of amount of combustion air at about 0.6.
Fig. 4.15 shows the relationship between feed loading of dewatered cake, ignition
loss of solid residue and the decomposition rate of combustibles. When the feed
loading of dewatered cake was below 25 kg/m2 -hr, as shown in the Figure, the igni-
tion loss of solid residue could be decreased almost to the same extent as in the case
of incineration. If the ignition loss is allowed to be 10^ the maximum feed loading
of dewatered cake, in case the water content of the cake is around 30% at the inlet
of the pyrolysis furnace, can be increased to 40 kg-DS/m2 -hr. It me'ans an increase
of 60%over the 25 kg-DS/m2 -hr, the feed loading of dewatered cake obtained in the
basic study.
Fig. 4.15 Variation of Both Ignition Loss of Solid Residue
and Decomposition Rate in Combustible to Feed
Loading of Dried Cake
Ratio of amount of combustion air =5 96
Pyrolyzing temp. = 900°C
o
ex
I
•o
IM
O
100
90
80
70
60
50
40
30
20
10
805
»— .
806
•~, 804 807 g
^--. --- *..?j
803
Decomposition rate in
combustible
809
Numerals show run
number of each
experiment in figure
Ignition loss of solid residue
809
804 807
805
10 20 30 40 50
Feed loading of dried cake (kg • DS/mJ • hr)
185
-------
Fig. 4.16 shows the relationship between feed loading of dewatered cake and
fuel consumption. The classification of the fuel consumed was made in the same
method as in the foregoing Fig. 4.14. It is learned that fuel consumption is greatly
influenced by feed loading of dewatered cake into the pyrolysis furnace. When feed
loading of dewatered cake is small, fuel consumption increases. In case the feed
loading of dewatered cake is larger than 25 kg-DS/m2 -hr, fuel consumption is 80 ~
90 litre per ton-wet cake.
In case the allowable ignition loss of solid residue is set at 10%, as mentioned
earlier, and when the feed loading of dewatered cake is 40 kg-DS/m2-hr, the
amount of fuel used for pyrolysis is about 30 litre per ton-wet cake and the total
fuel consumption is about 80 litre per ton-wet cake.
Fig. 4.16 Variation of Fuel Consumption to Feed Loading
of Dried Cake
Ratio of amount of combustion air % 0.6.
Pyrolyzing temp. = 900°C
160 -
805
o
I
o.
6
I
o
3
tL,
140 - \*'V'
- Total fuel consumption
\ ( Heat source chamber and propane for ^
120 - \
805 \
100 - *\
80 - Fuel consumptions.
for pyrolysis \
60-1 Heat source chamber T
and propane for pyrolysis
(^ furnace J
40 -
20 -
i i
10 20
l^ pyrolysis furnace and combustion chamber J
w
\ 806
o
\ 804 807
\o °_
803 808
\806 8Q4
*~— .^807
803 ^. 80g
•^^,^809
*
i i
30 40
Numerals show
run number of
each experiment
in figure
1
50
Feed loading of dried cake (kg • DS/m2 • hr)
4.4.3 PRODUCTS OF DRIED CAKE PYROLYSIS
a. Remaining Rate of Each Element in Solid Residue
The results of analyses of dewatered cake and solid residue are shown in
Table 4.9. Table 4.10 shows the remaining rate of each element in solid residue
calculated on the basis of Table 4.9. From Table 4.9 and Table 4.10, the elements
other than those remaining in solid residue show the amount or rate of elements
which are estimated to have gone out of the pyrolysis furnace. (Since exhaust gas is
treated in the scrubber and combustion chamber, the amount of elements actually
emitted into the air is decreased sharply.)
In the measurement of the amount remaining in solid residue or the remaining
186
-------
rate, results different from those in the basic study were obtained regarding some
elements. The elements found to have a high remaining rate in the experiments for
practical study was chloride, whose remaining rate was about 20%higher than in the
basic study. In contrast, the remaining rate of sulfer was about 30%lower than in
the basic study. In other words, most of the sulfer remained in solid residue in the
basic study, while the remaining rate of sulfer was below 60%in the experiments for
practical study. With regard to heavy metals, the amounts of cadmium and lead
remaining in solid residue decreased. It is considered that these changes are related
to pyrolyzing temperature.
The remaining rate of each element in solid residue changes according to
pyrolyzing temperature and it does not follow that pyrolysis is particularly superior
to incineration.
However, shown in Table 4.9 is an example denoting the superiority of pyroly-
sis over incineration. It concerns the fact that part of the hexavalent chromium
compounds in sludge is reduced by pyrolysis. This means that, unlike incineration,
pyrolysis does not form any new hexavalent chromium compounds but can reduce
even part of the compounds contained in sludge. This is a point where pyrolysis is
extremely superior to incineration.
Table 4.9 Analytical Results of Both Dewatered Cake and Solid Residue
Items
Dewatered
Cake
Solid
Residue
Items
Dewatered
Cake
Solid
Residue
Run
No.
803
804
803
804
Run
No.
803
804
803
804
Ignition
Loss
(%)
59.5
59.5
8.1
8.5
Hg
(ppm)
0.56
0.54
<0.05
<0.05
Gross
Calorific
Value
(Real/
kg-DS)
2,960
2,860
320
340
As
(ppm)
'5.4
5.0
6.9
8.1
C
(%)
28.4
28.3
3.0
3.9
Cd
(ppm)
11
10
3.4
3.6
H
(%)
4.1
4.2
0.18
0.18
Pb
(ppm)
270
240
98
100
N
(%)
3.1
3.1
<0.5
<0.5
Zn
(ppm)
1,200
1,300
2,500
2,900
S
(%)
1.1
1.0
1.5
1.3
Cu
(ppm)
640
610
1,500
1,500
O
(%)
27.0
27.0
13.0
13.0
Fe
(Ppm)
32,600
31,500
75,200
75,800
Cl
<%)
0.65
0.63
1.26
1.26
T-Cr
(ppm)
330
290
590
730
CN
(ppm)
6.9
3.5
0.23
0.20
Cr*6
(ppm)
8.6
7.8
5.9
6.0
NH3
(ppm)
2,900
1,400
910
170
Cr^-
-^f-Cr
(%)
2.6
2.6
1.0
0.8
Table 4.10 Remaining Rate of Each Element at the Cake of Drying - Pyrolysis Process
No
803
804
Gross
Calorific
Value
4.8
5.3
C
(%)
4.6
6.2
H
(%)
1.9
1.9
N
(%)
<7.1
<7.2
S
(%)
59.9
57.5
0
<%)
4.8
5.3
CL
<*)
85.4
88.5
CN
(%)
1.5
2.5
NH,
(%)
13.8
5.4
Hg
<1.5
<1.5
As
(%)
56.3
71.7
Cd
(%)
13.6
15.9
Pb
(%)
16.0
18.4
Zn
(%)
91.8
98.7
Cu
(%)
103.3
108.8
Fe
(%)
101.7
106.5
T-Cr
(%)
78.8
111.4
187
-------
b. Concentration and Particle Size Distribution of Dust
As shown by Table 4.11, the concentration of dust from the pyrolysis furnace
is considerably high. The concentration of dust is lowered sharply after dust is sent
through the scrubber, but it is necessary to install an electric precipitator or other
equipment in order to hold down the dust concentration rate below 0.34 g/Nm3.
Much of the dust from the pyrolysis furnace has a relatively large particle size
as shown in Table 4.12. Accordingly, it is considered to be comparatively easy to
separate dust by an electric precipitator or other equipment.
Table 4.11 Characteristics of Exhaust Gas (Run No.803)
Sam-
pling
Site
G,
G,
G4
G,
Temp.
of
Gas
<°C)
-
760
215
49
Velocity
of
Gas
(m/sec.)
-
13.8
16.1
1.4
Moisture
Contents
(Vol. %)
Actual
24.6
20.8
10.3
Calcu-
lation
14.5
24.7
21.8
10.4
Volume of
Dry Gas
(Nm3/hr.)
Actual
200
330
280
Calcu-
lation
103
213
308
275
Dust
(g/Nm3)
-
8.4
3.1
0.34
HCN
(ppm)
-
240
<0.1
<0.1
NH3
(ppm)
-
2.080
1.0
0.5
NOx
(ppm)
170
54
210
190
SOx
(ppm)
130
130
230
130
HC1
(ppm)
-
6.0
15.0
1.4
CI,
(ppm)
<0.2
<0.2
<0.2
<0.2
Degree
of
Odor
(Times)
-
400
2
2
Remark: G2. Exhaust Gas Samples from Heat Source Chamber
G3: Exhaust Gas Samples from Pyrolysis Furnace
G4. Exhaust Gas Samples from Exhaust Gas Boiler
G5: Exhaust Gas Samples from Gas Scrubber
Table 4.12 Dust Size Distribution in Exhaust Gas from Pyrolysis Furnace
(Run No.804)
Size (M)
Samples
1
2
>6.5
73.8
70.2
4.3-6.5
12.1
12.9
2.8-4.3
6.1
5.8
1.9-2.8
3.2
3.6
1.2-1.9
1.5
2.1
0.6-1.2
0.6
0.9
0.4-1.6
0.9
1.0
0.2-0.4
1.2
1.3
<0.2
0.6
2.2
c. Components of Exhaust Gas
Table 4.11 shows the results of analyses of such exhaust gas components as
hydrogen cyanide, ammonia, NOX and SOX. The amounts of various exhaust gas
components generated in the pyrolysis furnace diminish sharply in the process of
decomposition in the combustion chamber and cleaning by the scrubber. For this
reason, hydrogen cyanide, ammonia and hydrogen chloride will do no harm.
However, the amounts of NOX and SOX do not decrease. Especially, the concent-
ration of NOX is much higher in exhaust gas than at the outlet of the pyrolysis
furnace, since it is treated in the combustion chamber at temperatures over 1,000°C.
Thus it may become necessary to take steps to remove SOX and NOX, as in the case
of incineration, where the environmental quality standard on air pollution is being
enforced strictly.
d. Behavior of Nitrogen, Sulfer and Chloride in Sludge
The forms of nitrogen, sulfer and chloride at the outlet of the pyrolysis furnace
188
-------
is shown in Fig. 4.17. There is hardly any difference in the results of analysis of
nitrogen between the experiments for practical study and the basic study (See
Fig. 4.12). In the case of sulfer, the results of analysis differed from those in the
basic study, with the whereabout of about 27% of the substance unknown. As a
result of measurement, it was found that the amount of sulfer remaining in solid
residue decreased, while an increased amount of SOX was generated.
The amount of chloride remaining in solid residue tended to go up by about
20% from the level recorded in the basic study.
Fig. 4.17 Forms of Each Element in Product of
Pyrolysis
100
90
80
70
60
50
40
30
20
10
0
13.3
0.29
12.4
60.3
2.1
19.8
85.6
Remark
N
C2
} HCN gas
} NH3 gas
I Solid residue
H2Sgas
} SOX gas
Solid residue
} HC8 gas
} Solid residue
N
e. Offensive Odor Components in Exhaust Gas
Table 4.13 shows the results of analyses of offensive odor components in
exhaust gas. Obtained from the analyses were numerical values almost similar to
those in the basic study. The main offensive odor components generated in the
indirect steam dryer are ammonia and acetaldehyde, and those generated in the
pyrolysis furnace are high concentrations of ammonia, hydrogen sulfide and form-
aldehyde.
Although most of the components are decreased in amount through the de-
composition in the combustion chamber, the amounts of ammonia, acetaldehyde
and formaldehyde remaining in exhaust gas were found to be considerably higher
than those recorded in the basic study.
189
-------
Table 4.13 Analytical Results of Offensive Odor Component in Exhaust Gas
Sampling
Site
G
G3
G4 1
H2S
(ppm)
0.07
5.0
<0 008
Methyl
Mercaptan
(ppm)
<0.005
<0.005
<0.005
Methyl
Sulfide
(ppm)
0.08
<0.003
<0.003
Tri-methyl
Amine
(ppm)
0.005
0.002
0.002
Ammonia
(ppm)
8.7
2.080
1.0
Dimethyl
Disulfide
(ppm)
0.5
0.03
<0.002
Sterane
(ppm)
<0.3
<3
<0.02
Acetalde-
hyde
(ppm)
1.0
0.1
0.07
Formal-
dehyde
(ppm)
<0.15
3.9
0.44
Acetic
Acid
(ppm)
<3.0
<3.0
<3.0
Carbon
Disulfide
(Ppm)
0.07
0.6
0.006
Remark: G, . Exhaust Gas Sample from Indirect Steam Dryer
G3. Exhaust Gas Sample from Pyrolysis Furnace
G,: Exhaust Gas Sample from Exhaust Gas Boiler
4.4.4 COMPARISON OF DRYING-PYROLYSIS PROCESS, DIRECT
PYROLYSIS PROCESS AND INCINERATION PROCESS
Experiments were conducted on the direct pyrolysis process and incineration
process of dewatered cakes to find out the merits and demerits of the drying-
pyrolysis process. The results of the experiments are shown in Table 4.14. It shows
the results of the Run No. 808 as an example of the drying-pyrolysis process. The
properties of the dewatered cake used in Run No. 808 in Table 4.14 is a little dif-
ferent from the dewatered cakes used in Run No. 903 and No. 904. The cake used
in Run No. 808 has less combustibles than dewatered cakes used in Run No. 903
and No. 904 and, therefore, its calorific value is small. It was difficult to compare
the three processes exactly, but it was concluded that a tentative comparison would
be possible.
In Table 4.14, Column I shows empirical values and Column II the values
revised for practical reasons. The revision was made in the following manners.
i) In the drying-pyrolysis process, it was assumed that the temperature of return-
ing water from the drain was 80° C and that measures were taken to prevent white
smokes of exhaust gas from gonig out of the chimney.
ii) In the direct pyrolysis process and incineration process of dewatered cakes,
it was assumed that heat exchange was done by a heat exchanger, in addition to
the revision made in above Article i).
Under these revisions, fuel consumption for the drying-pyrolysis process
rises higher than the empirical value and fuel consumption for direct pyrolysis
process and incineration process goes down from the empirical values. Nevertheless,
fuel consumption for the drying-pyrolysis process is about 1/2 of that needed for
direct pyrolysis process and about 1/3 of that for incineration process.
The amount of exhaust gas generated by drying-pyrolysis process becomes
considerably smaller than that generated by direct pyrolysis process or incinera-
tion process. This means that the drying-pyrolysis process could lower the costs
of construction and operation of facilities to prevent air pollution, by a larger
margin than direct pyrolysis process and incineration process.
Comparing direct pyrolysis process with incineration process, the former is
also considered to be considerably more advantageous than the latter economically.
The experiments were conducted at a pilot plant, and the operation of a
practical plant is expected to produce results considerably different from those
obtained in the foregoing experiments. For example, in the experiments of Run
190
-------
Table 4.14 Comparable Experimental Data of Drying-Pyrolysis
Process, Direct Pyrolysis Process and Incineration Process
^ __ Process
^^— — -
Items
• — -^__ "57 r~—- —
--— JlljnNo.
Moisture Contents of Dewatered Cake (%)
Ignition Loss of Cake (%)
Ash Contents of Cake (%)
Gross Calorific Value (Kcal/kg-DS)
Moisture Contents at Inlet of Pyrolysis ,„,,
Furnace (%>
Ratio of Amount of Combustion Air
Exhaust Gas Temperature at Outlet of ,0.-,,
Pyrolysis Furnace *• '
Exhaust Gas Temperature at Outlet of ,0,-,,
Combustion Chamber *• '
Fuel Consumption
(I/ ton -Cake)
Dry Exhaust Gas
(Nm3 /ton-Cake)
Wet Exhaust Gas
(Nm3 /ton -Cake)
I
II
I
II
I
II
Furnace
Combustion Chamber
Total
Furnace
Combustion Chamber
Total
Furnace
Combustion Chamber
Furnace
Combustion Chamber
Furnace
Combustion Chamber
Furnace
Combustion Chamber
Drying-
Pyrolysis
808
16.5
59.5
40.5
2,900
40.4
0.71
850
1,100
33
39
72
33
61
94
858
1,428
858
1,556
1,199
1,651
1,199
1,651
Direct
Pyrolysis
903
77.8
66.0
34
3,300
77.8
0.60
393
800
144
89
233
144
44
188
1,495
2,227
1,495
2,184
2,748
2,381
2,748
2,339
Incinera-
tion
904
77.5
66.0
34
3,300
77.5
2.0
485
800
128
234
362
128
162
290
2,673
4,968
2,673
4,425
3,949
5,350
3,949
4,727
No. 903 and No. 904, the temperatures at the outlet of the furnace were consider-
ably higher than at the outlet of the furnace for practical use.
For this reason, trial calculations were made on drying-pyrolysis, direct
pyrolysis and incineration in a practical use furnace (Wet Base 50 t/day) by in-
troducing the idea of designing a conventional multi-hearth furnace. The results of
the calculations are shown in Table 4.15.
In the drying-pyrolysis process, as shown in the Table, no fuel is supplied to
the pyrolysis furnace at all since sludge cake is in a dry state. And only a small
amount of fuel is needed for the process because exhaust gas generated in the
pyrolysis furnace is used as part of the heat source for boiler. In direct pyrolysis,
fuel consumption for the pyrolysis furnace is the largest, but that for the com-
bustion chamber is less than for the drying-pyrolysis process because no fuel is
needed for the boiler in the combustion chamber. In incineration, less fuel is
supplied to the furnace than in direct pyrolysis since combustibles are burned in the
furnace, but the amount of fuel used in the combustion chamber for the combustion
of exhaust gas is very large. But if there is no combustion of exhaust gas, the
amount of fuel for incineration is the smallest. In reality, however, sewage treat-
ment plants in most of the municipalities in Japan are equipped with facilities for
191
-------
Table 4.15 Comparable Calculation Results of Drying-Pyrolysis
Process, Direct Pyrolysis Process and Incineration Process
— _^___^ Process
Items " ~- — ~^____
Moisture Contents of Dewatered Cake (%)
Ignition Loss of Cake (%)
Ash Contents of Cake (%)
Gross Calorific Value (Kcal/kg-DS)
Moisture Contents at Inlet of Pyrolysis I0,\
Furnace {/o)
Ratio of Amount of Combustion Air
Exhaust Gas Temperature at Outlet of fTl
Pyrolysis Furnace ^ '
Exhaust Gas Temperature at Outlet of ,0,-,..
Combustion Chamber l •*
Fuel Consumption
(I/ ton-Cake)
Dry Exhaust Gas
(Mm3 /ton-Cake)
Wet Exhaust Gas
(Nm3 /ton-Cake)
Furnace
Combustion Chamber
Total
Furnace
Combustion Chamber
Furnace
Combustion Chamber
Drying-
Pyrolysis
Process
78
66.0
34
3,300
25
0.60
700
1,100
0
52
52
338
1,302
542
1,408
Direct
Pyrolysis
Process
78
66.0
34
3,300
78
0.60
200
800
44
33
77
879
1,467
1,985
1,636
Incinera-
tion
Process
78
66.0
34
3,300
78
2.0
200
800
27
120
147
2,023
3,302
3,172
3,638
the combustion of exhaust gas or for the deodorization by catalyzer in order to
prevent the generation of offensive odor and the emission of white smokes from
chimneys.
Pyrolysis process can decrease exhaust gas sharply, compared with incineration
process. Therefore, pyrolysis process requires less costs of construction and
operation of such exhaust gas control facilities as electric precipitators and alkali
absorption scrubber. In this respect, pyrolysis process can be said to have a great
economic advantage.
4.5 SUMMARY
Basic and practical studies were carried out on the drying-pyrolysis process in
order to put to practical use the pyrolysis of sewage sludge by a multi-hearth
furnace. The sampled sludge for use in these studies was dewatered cake of raw
sludge at the Toba Sewage Treatment Plant in Kyoto. The pilot plant for the basic
study was made up of a two-shaft indirect steam dryer, a single-hearth furnace (with
a total furnace floor space of 2.1 m2) and its incidental facilities. The pilot plant
for the experiments for practical study consisted of a four-shaft indirect steam
dryer, a four-hearth furnace (with a total furnace floor space of 1.63 m2) and its
incidental facilities.
The results of the studies can be summarized as follows.
(1) As a result of the experiments for practical study, the Overall Heat Transfer
Coefficient (U) of the indirect steam dryer for sludge cakes drying could be raised
to 140 ~ 170 Kcal/m2 -hr-°C. It is larger than the Overall Heat Transfer Coefficient
of 70 ~ 110 Kcal/m2 -hr-°C obtained in the basic study. This is ascribed to the in-
crease in the number of shafts of the indirect steam dryer.
192
-------
(2) For the drying-pyrolysis process, it is appropriate to set the ratio of amount of
combustion air at 0.5 ~ 0,7 and pyrolyzing temperature at 900°C in order to keep
the ignition loss of solid residue below 10%. According to the experiments for
practical study, adequate feed loading of dewatered cake to maintain the same con-
dition is estimated to be 40 kg-DS/m2 -hr.
(3) Pyrolysis can completely prevent the oxidization into hexavalent chromium
compounds, of trivalent chromium compounds contained in sludge cakes. And part
of the hexavalent chromium compounds contained in sludge cake are reduced in the
furnace by reducing gas generated in the pyrolysis furnace.
(4) At the basic and practical studies, there were found to produce slightly dif-
ferent results with regard to the remaining rate of each element in solid residue from
pyrolysis. The difference relates to pyrolyzing temperature. The remaining rate of
each element in solid residue is related to temperature, and it does not follow that
pyrolysis is by far superior to incineration.
(5) The amount of dust generated in pyrolysis furnace is considerably large.
Furthermore, many particles are large in size. Although most of the dust can be
removed when passed through the scrubber, it is also necessary to install an electric
precipitator for maintaining the concentration of dust at a very low level as same
as the case of incineration process.
(6) Of the exhaust gas components generated in the pyrolysis furnace, hydrogen
cyanide and ammonia are decomposed in the combustion chamber. Hydrogen
chloride can be removed by means of a gas scrubber. Since SOX and NOX cannot be
removed, however, it may become necessary to take measures to deal with the
problem in areas where the environmental quality standard on air pollution is
strictly enforced.
(7) The main offensive odor components in exhaust gas generated in the indirect
steam dryer are ammonia and acetaldehyde, and those generated in the pyrolysis
furnace are much amount of ammonia, hydrogen sulfide and formaldehyde. Most
of these components are diminished through the decomposition in the combustion
chamber, but small amounts of ammonia, acetaldehyde and formaldehyde remain
in exhaust gas at the outlet of combustion chamber.
(8) The drying-pyrolysis process consumes the least amount of fuel in case there is
combustion of exhaust gas. But, in case the combustion of exhaust gas is not
needed, incineration process consumes the least amount of fuel.
The drying-pyrolysis process and direct pyrolysis process can reduce the
generation of exhaust gas to below 1/2 of the amount of exhaust gas generated by
incineration process. Therefore, pyrolysis process is expected to have a great
economic efficiency in case steps are necessary to prevent air pollution and offensive
odor.
REFERENCE
(1) T. Majima et al, Studies on Pyrolysis Process of Sewage Sludge, Proceedings of
the 8th International Conference on Water Pollution Research, Sydney, p. 381
(1976)
193
-------
FIFTH US/JAPAN CONFERENCE
ON
SEWAGE TREATMENT TECHNOLOGY
PAPER NO, 4
DEVELOPMENT AND EVALUATION OF AUTOMATIC
WATER QUALITY MONITORING EQUIPMENT
APRIL 26-28, 1977
TOKYO, JAPAN
MINISTRY OF CONSTRUCTION
JAPANESE GOVERNMENT
195
-------
DEVELOPMENT AND EVALUATION OF AUTOMATIC WATER
QUALITY MONITORING EQUIPMENT
K. Murakami, PWRI, Ministry of Construction
196
-------
DEVELOPMENT AND EVALUATION OF AUTOMATIC
WATER QUALITY MONITORING EQUIPMENT
1. Foreward 198
2. Automatic Measuring Devices to Monitor Quality of Raw Sewage 198
2.1 Total Cyanide Monitor 198
2.2 Surface Oil Detector 204
2.3 Future Development Projects 206
3. Automatic Water Quality Measurement Devices to Control Waste water
Treatment Process 206
3.1 TOC Analyzer 206
3.2 Continuous UV Photometer 209
3.3 Automatic SV and SVI Meter 212
3.4 Automated Colorimetric Analyzer for Phosphorus 214
3.5 Other Measuring Instruments 214
3.5.1 Automatic Cleaning Unit for Dissolved Oxygen Electrode 214
3.5.2 Ultrasonic Wave Sludge Density Meter 215
3.5.3 Sludge Level Meter 215
197
-------
DEVELOPMENT AND EVALUATION OF AUTOMATIC WATER QUALITY
MONITORING EQUIPMENT
1. FOREWORD
In the field of sewage works, there is a pressing need for the development of
reliable automatic water quality measuring devices for monitoring sewage quality
including industrial wastewater discharged into the public sewage system and for
automatic control of treatment processes.
The Ministry of Construction gives high priority to the development of measur-
ing devices for detecting toxic substances that may be contained in industrial waste-
water discharged into the public sewage system. The development of such measur-
ing devices are now being carried out by a contract research with the Association of
Electrical Engineering.
The Electrical Engineering Association organized a committee composed of
representatives from nine manufacturers and users for this purpose, and has been
conducting field tests on the previously developed devices to seek for any possible
technical improvement and developing new instruments with the cooperation of the
manufacturers.
The development of measuring instruments for automatic control of treatment
processes has also progressed considerably these days. Although their application
to automatic control is not so popular yet, these instruments are being installed in
many sewage treatment plants for manual control or monitoring.
This report summarizes the activities in the field of research and development
of water quality measuring devices in Japan.
2. AUTOMATIC MEASURING DEVICES TO MONITOR QUALITY OF RAW
SEWAGE
2.1 TOTAL CYANIDE MONITOR
On a contract research basis entrusted to the Association of Electrical Engineer-
ing, work has begun to develop a total cyanide monitor from FY 1975. At that
time, five models of automatic cyanide monitors from different manufacturers
were on the market. Those units, however, were all designed for monitoring
cyanides in industrial wastewater which is usually easy to deal with, and the appli-
cability of these products to sewage was unclear. Therefore, field tests of these units
were conducted at a sewage treatment plant for about three months. It was revealed
that the two models were completely uncapable of continuous operation and the
other models, although giving comparatively good results, all had defects. Therefore,
efforts were made to develop the New Standard Models by improving previous
models. Three prototype models were assembled.
Models I and II are batch-type measuring instruments. Model I incorporats the
method of removing sulfides during distillation while Model II employs the method
198
-------
of removing sulfides after distillation. Type III, on the other hand, is of a con-
tinuous measuring type.
All of these prototype models utilize cyanide electrodes as the detector unit.
Models I and II have two kinds of electrodes: conventional type electrode with an
abrasive unit, and an electrode with the measuring cell itself being a sensing element
as shown in Fig. 1.
Fig. 1 New Type Cyanide Electrode
Reference electrode
Teflon coated roter
Sensing element
The surface of the sensing element of the latter type electrode is constantly
cleaned by a rotor. This electrode, when compared with conventional ones, has a
lower detecting limit giving a longarithmicly linear output down to 0.01 mg/fi.
Fig. 2 shows the flow diagram of Model I monitor. After measuring 100 m£ of
sulfuric acid (1+9) and 10 m£ of N/10 potassium permenganate solution is added
to oxidize sulfides and other interferences. Next, before raising the temperature too
high, 10 m£ of N/10 sodium oxalate is added to remove excessive potassium per-
menganate without decomposing cyanides. The distilled cyanide is absorbed in a
0.4% sodium hydrate solution and measured by cyanide electrodes. Measurements
are done at 30 minute intervals.
199
-------
to
o
o
Sample
VMC: Volume Measuring Cup
PV: Pinch Valve
SV: Solenoid Valve
P: Pump
NF: Level Detector
FS: Float Switch
Fig. 2 MOW Diagram of Total Cyanide Monitor, Model
FS,
Tap water
Drain
nnrtro"o irv$$oo l
O Heater O
Drain
-------
Fig. 3 Flow Diagram of Total Cyanide Monitor, Model II
INi
o
VMC: Volume Measuring Cup
PV- Pinch Valve
SV: Solenoid Valve
P Pump
AP. Air Pump
Drain
-------
Fig. 4 How Diagram of Total Cyanide Monitor, Model III
P- Proportioning Pump
AP- A,i Pump
PV Pinch Valve
SV: Solenoid Valve
SpV- Slop Valve
NV: Needle Valve
MS' Magnetic Stirrer
Tap water
Standard
solution
Sample
Drain
-------
Model II is also of a batch type. As shown in the flow diagram in Fig. 3, the
system consists of distillation under acidic condition with phosphoric acid and
removal of hydrogen sulfide after distillation.
100 mC of sample water, added with 10 mC of phosphoric acid, is distilled and
distilled cyanide is absorbed in 2% sodium hydroxide solution in the receiving flask.
The hydrogen sulfide, distilled together with hydrogen cyanide, is removed by the
column either filled with the bismuth treated chilate resin or granular lead peroxide.
The bismuth treated chilate resin is a chilate resin reacted with 0.4 ~ 0.5 mM
bismuth per 1 (one) mC resin. Theoretically it has a capacity to remove equivalent
hydrogen sulfide.
The use of such resin prevents the heavy metal for sulfides removal from being
discharged into the effluent.
Lead peroxide oxidizes hydrogen sulfide into sulfate ion without producing
any complex ion of cyanide. The time interval of measurements by this model is
one hour.
Model III is of a continuous measuring type as shown in the flow diagram in
Fig. 4.
200 mfi/hr of sample water is continuously supplied into the distillation flask
and distilled almost instantaneously by heated phosphoric acid in the flask. 2%
sodium hydrate solution at a flow rate of 10 m£/hr is added to the distillate, and the
cyanide is measured by an electrode. Since non-distillated substances such as
minerals accumulate in the distillation flask, phosphoric acid is replaced once every
day to wash the flask.
Sulfides, as is in Model II, are removed after distillation by permeating the
distillate through the desulfurizing column.
These three type units, completed in December 1976, are currently undergoing
field tests at an actual sewage treatment plant. The influent to the plant is mainly
composed of metal-finishing wastewater and contains very small amount of dome-
stic sewage. The water sample presently used for the field test is the chemical
clarified effluent from the plant.
Major troubles found during the field test were:
(a) Distillation efficiency during night time deteriorated due to insufficient distil-
lation heater capacity of Models I and II.
(b) Cyanide recovery rate was inconsistent owing to dew drops developing in the
tube linking the condenser with the distillate receiver, and
(c) Some substance in the tap water which was used for wash water interfered the
measurement. This substance is considered to be either free chlorine or the sub-
stance which forms a complex cyanide compound.
Modifications of the instruments were made, and field tests are presently con-
ducted of the modified units.
After completing the test using clarified effluent, field tests will be continued
using raw sewage as the sample.
203
-------
2.2 SURFACE OIL DETECTOR
Contract research with the Association of Electrical Engineering also covers
evaluation and development of surface oil detectors. Various types of oil detectors
are already on the market. Two types of surface oil detectors were selected to carry
out field tests for examining their applicability. One model is based on the fluore-
scence emitted from oils being irradiated by UV rays. The other model is based on
the difference in reflectivities between oils and water. Both models have essentially
the same structures. A pair of turbular floats support a light source and a light
receiver, keeping a prefixed distance between the detector unit and the water
surface.
In former type oil detector, an ultra-violet ray of 253.7 nm in wave length is
projected and the fluorescence light is detected by a photo multiplier. It can detect
crude oil, heavy oil and lubricants. However, it is not good for oils that do not pro-
duce fluorescence, such as gasoline, kerosene, vegetable oil and animal fat. As far
as the detectable oils are concerned, the detector can measure the oil film thickness
to a certain degree when the type of the oil is given. This detector has an automatic
calibration mechanism that can correct the effects of the deterioration of light
source and temperature changes.
The field test lasted for about a month and a half without producing any
mechanical malfunctions thus satisfactory measurement results were obtained.
Possible interferences may be detergent fluorescent and phenol contained in the
sewage. However, the baseline drift during the field test was extremely small, and
the interferences can be considered negligible.
The principle of measurement of the other model is the difference in the
reflectivities between water and oil. The water reflectivity is normally 2%, and that
of oil is between 3.5 and 6% depending upon the type of oil. Hence, the existence
of surface oil can be detected by merely measuring the reflectivity. The pulsed
infrared beam is used to minimize the effect of the ambient light. Dissolved and
suspended elements in the water do not interefere with the measurements.
During a month and a half long field test, no maintenance was necessary except
when scum covered the whole water surface, and the performance was satisfactory.
Both oil detectors mentioned above has comparatively large floats and require
a wide space to install. Therefore, it was planned to develope an oil detector which
needs smaller space. The new model being developed is also based on the difference
in reflectivities between water and oil but uses a laser as the light source. Since the
intensity of laser beam is practically indipendent on the light path, the reflectivity
measurement is scarcely affected by v,;ater level changes, which eliminates the
necessity of the floats. The block diagram of the barrack model is shown in Fig. 5.
The light source is 1 mW He-Ne laser with wave length of 633 nm. The light
beam from the lazer is projected on the water surface via the mirror through a
transparent part at the center. A part of the light reflected on the reverse side of
the mirror goes into the photo cell on the left side as a reference. The reflected
light from the water surface travels to the concave mirror via the central mirror and
gathers at the photo cell for detection.
204
-------
Fig. 5 Block Diagram of Surface Oil Detector Using Laser Beam
Laser
Mirror
Photo Cell for Reference
Concave Mirror
Photo Cell for Detection
7" Amplifiers
Syncroscope
9: Water Surface
The barrack model employs a synchroscope to read the output from the photo
cells. The intensity of the laser beam is comparatively strong, so that the effect of
the ambient light seems to be small. But it may be necessary to use a pulsed beam
by means of a chopper to put the model into practical use.
Further studies are being done on the output system and so on. Laboratory
and field tests are currently under way. This model, upon completion for practical
use, will enable measurement even in narrow manholes.
205
-------
2.3 FUTURE DEVELOPMENT PROJECTS
The contract research entrusted to the Association of Electrical Engineering
will include studies of (a) developing total-chromium and copper monitors based on
automated colorimetric analysis, (b) developing a cadmium monitor based on ion
selective electrode method and (c) conducting field test to examine the feasibilities
of these devices for future practical use.
With regards to total chromium and copper monitors, automated colorimetric
analysis would be a practical method since regents appropriate for automation are
available. Products based on this method are already on the market. Presently,
researches are conducted on the pretreatment methods to maximize the dissolved
fractions of chromium and copper in sewage.
Automated colorimetric analysis of cadmium does not seem to be practicable,
as suitable reagents are not available yet. Ion selective electrode for cadmium,
although promissing, is interfered greately by organic substances. Therefore,
methods to effectively remove organic interferences are now being studied.
Furthermore, basic studies will be initiated to apply flameless atomic absorp-
tion spectometry and anode stripping voltimetry methods to water quality monitors.
3. AUTOMATIC WATER QUALITY MEASUREMENT DEVICES TO
CONTROL WASTEWATER TREATMENT PROCESS
3.1 TOC ANALYZER
Nishiyama Sewage Treatment Plant is utilized as a demonstration plant to
evaleate the effect of chemical coagulat addition to the aeration tank. A continuous
TOC analyzer was installed at the plant on March 1976 and has been operated
successfully. This TOC analyzer is an improved version based on the experimences
at the Morigasaki Sewage Treatment Plant and the Arakawa River Left Bank Sewage
Treatment Plant, as presented at the 4th Conference.
The major purpose of this TOC analyzer installation is to study the conversion
of dissolved organics into activated sludge in the biological treatment process.
Hovvever, die sampling system is designed to feed the analyzer the following four
kinds of samples at 90 min. intervals in turns by an automatic sample exchanger:
primary effluent, secondary effluents from both control and chemical addition
systems, and filtered secondary effluent.
Suspended solids in primary effluent is removed by a compact continuous
centrifuge having a bowl capacity of 3 liters. This centrifuge requires manual Inter-
mittent operation to discharge centrifuged solids every two weeks. By conducting
centrifugal operation under the feed rate of 2.5 £/min. at 4,000 rpm, 30 ~ 80 mg/2
suspended solids in the primary effluent can be lowered to 5 ~ 10 mg/£.
206
-------
Several minor troubles developed since commencing continuous operation of
the analyzer. But none was so serious to stop the measurement, and data were
obtained almost 100% of the period.
Troubles experienced so far are as follows:
(1) The tubing at the inlet and outlet of the infrared analyzer deteriorated in
quality faster than expected. The replacement of the tubing can be done only by
the manufacturer.
(2) The cleaning of the scrubber for 1C removal is extremely difficult because of its
ill-designed setup.
(3) The sample feed pump clogged often.
(4) The pipe at the outlet of the furnace corroded considerably, and should be
replaced within one year.
(5) The corrosion of the inside of the furnace was observed.
(6) The humidity of the air used as the carrier gas was very high, resulting in fre-
quent replacement of the dehumidifying silica gel.
(7) The performance of dust filter in front of the infrared analyzer was poor. Thus
it was replaced by a glass wool filter which caused a new trouble of condensation of
moisture.
Samples were taken from the scrubber of the continuous TOC analyzer, and
TOC was measured by a laboratory-type TOC analyzer. Fig. 6 shows the compari-
son of TOC thus obtained with that by the continuous analyzer. Fairly good corre-
lation is observed.
Fig. 7 shows the comparison of TOC obtained by manual sampling and analysis
of primary and secondary effluents with that obtained by the continuous TOC at
the same time. The black circles and triangles in the Figure indicate total TOC
manually analyzed, and the white ones represent dissolved TOC manually analyzed.
According to Fig. 7, the continuous TOC analyzer gives data close to the
measurement of the dissolved TOC. As to the primary effluent, suspended solids
removal is done by a centrifuge as mentioned before. However, with regards to
other samples, no provision is made for SS removal except a coarse filter for removal
of larger materials. Therefore, a considerable portion of SS seems to be removed in
the sampling and 1C removal system.
Fig. 7 also indicates that the correlation between dissolved TOC by manual
analyses and TOC obtained from the continuous TOC analyzer is worse than that
shown in Fig. 6, implicating not only loss of SS in the sampling system but also a
possible change of water quality in other form may exist.
The TOC analyzer of this type is considered most appropriate for water sample
containing high SS among the continuous TOC analyzers currently on the market.
However, at this stage it can be concluded that the continuous measurement of total
TOC is not practicable.
207
-------
Fig. 6 Comparison of TOC, Manual and Automatic Analyses
- Samples taken at the outlet of the scrubber in the TOC monitor -
50
TOC, Automatic Analysis (mg/S)
Fig. 7 Comparison of TOC, Manual and Automatic Analyses
A A Primary Effluent
O • Secondary Effluent
D Filtered Secondary Effluent
,• and A refer to Total TOC
manually measured.
20 30 40
TOC, Automatic Analysis (mg/8)
50
00
208
-------
3.2 CONTINUOUS UV PHOTOMETER
Most of the organic substances bear the nature of UV absorbance. Being based
on this principle, continuous UV photometer is sold on the market as a organic
content monitor.
The correlation between UV absorbance and TOC of various kinds of sewage
was investigated extensively by laboratory analyses. It was found that comparative-
ly good correlation was seen when water sample was of the same type. Therefore,
continuous UV photometers were installed at the Nishiyama Demonstration Plant
and Toba Pilot Plant for the field evaluation.
This continuous UV photometer measures the extinction of 254 nm UV beam.
The turbidity influence is corrected by taking the ratio of transmitted light intensi-
ties of ultraviolet and visible rays. Soon after continuous operation was started, it
was discovered that the ambient temperature variation affected the measurement
significantly. The temperature characteristic of the detector unit is described in
Fig. 8. Accordingly, the photometer was remodelled to put the detector unit in a
constant temperature box of*40°C. An activated carbon column was installed at the
exhaust pipe of the constant temperature box to remove ozone generated in the
box.
Fig. 8 Effect of Ambient Temperature on UV Absorbance Measurement
20 30 40
Ambient Temperature (°C)
Fig. 9 shows the relationship between UV absorbance and TOC (value obtained
by continuous TOC analyzer) at the Nishiyama Demonstration Plant, which seems
relevant with the exponential function.
Fig. 10 shows the relationship between UV absorbance and turbidity with
regards to primary effluent. Judging from this figure, there is no correlation be-
tween them, therefore, the influence of turbidity seems to be compensated.
Fig. 11 is the data obtained at the Toba Pilot Plant. Each datum represents an
average of 12 values obtained from analyses of 24 hours composite samples. Accord-
ing to Fig. 11, the data tendencies of activated carbon effluent and other effluents
differ slightly. This may be because the residual organic compounds in the activated
carbon effluent are composed mainly of those with no UV absorbance, such as
polisucroses.
209
-------
80-
70-
60-
50-
8
Fig. 9 Relationship between UV Absorbance and TOC (Automatic Analyzer)
[ A Primary Effluent
Legend I ° Secondary Effluent A ^
I • Secondary Effluent (Alum Addition)
I A Filtered Secondary Effluent
A
A A
^
A A
30-
20-
10-
0.5
10
UV Absorbance
l.'S
2o
-------
Fig. 10 Effect of Turbidity on UV Absorbance - Samples are primary effluent.
80
70-
60
50--
40
30
0.5
l.O
UV Absorbance
1.5
2.0
Fig. 11 Relationship between UV Absorbance and TOC, Toba Pilot Plant
ST: Secondary Treatment
F: Filtration
20
15
c*
1 10
o
o
5
C
CC: Chemical Clarification
AC: Activated Carbon Adsorption
a
a
A
0 <9
D ST + F
A ST + CC + F
n ST + F + AC or
ST + CC + F + AC
0.1 0.2 0.3 0.4 0.5
UV Absorbance
211
-------
3.3 AUTOMATIC SV AND SVI METER
SV and SVI are useful indexes for operation and maintenance of the activated
sludge process. A couple of SV and SVI meters are already on the market. Fig. 12
shows an example of a block diagram. The mechanicms of each SV and SVI meter
is virtually the same.
After air lifting the water sample from the aeration tank into the settling tube
of 170mm in inside diameter, MLSS is first measured by the SS meter of the
scattering light method with air being injected from the bottom for mixing. The
meter reading is registered in the memorizing unit.
Next the stirring is stopped, to conduct SV measurement. Light source and
photo cell installed outside the settling tube are descended by a motor until the
transmitted light intensity becomes lower than the fixed level, thus the light source
and the photo cell follow constantly the position of the sludge level. The SV value
is detected by the potentiometer, connected to the motor, 30 min. after the start of
settling. Based on these MLSS and SV measurements, SVI is computed electrically.
At each measuring time, the inside of the settling tube is cleaned automatically by
a brush to prevent interference by stain.
Fig. 12 Block Diagram of SV and SVI Meter
Leaf Chain
Brush Rotating Motor ( U
Brush Shaking Motor
Potentiometer
212
-------
The SV and SVI meters are actually in use at many sewage treatment plants
and are generally working well. Figs. 13 and 14 shows the comparisons of SV and
MLSS obtained by an automatic meter and manual analyses at a sewage treatment
plant in Aichi Prefecture. The figures indicate that both values agree fairly well.
It was observed, however, that color of the sewage sometimes effected the
MLSS or the SVI measurements. Therefore, modification of the meter by mounting
another SS meter on the top-side of the settling tube is being investigated in order to
correct the effect of color variation.
Fig. 13 Comparison of SV, Manual and Automatic Measurement
15 20
SV, Manual Measurement (%)
Fig. 14 Comparison of MLSS, Manual and Automatic Measurements
1000 1500 2000 2500
MLSS, Manual Analysis (mg/8)
213
-------
3.4 AUTOMATED COLORIMETRIC ANALYZER FOR PHOSPHORUS
At the Nishiyama Demonstration Plant, continuous measurement of dissolved
hydrizable phosphorus in primary and secondary effluents is carried out for the
purposes of mole ratio control of chemical addition and others. The measuring
device basically is the same as the automated colorimetric analyzer for ammonia,
which was reported at the 4th conference, except that it uses a filter paper for filtra-
tion and a hydrogen peroxide solution for cleaning.
The measuring device, installed in December, 1976, has been operated for
several months. This device has an automatic calibration mechanism, and it assures
certain level of accuracy. Data obtained by the automatic analyser agreed well with
those attained by manual analyses. However, the device developed a number of
mechanical troubles as listed below, leaving room for further improvement.
(1) For some reasons, when the flow ratio of sample and reagents or that of sample
and air for separation is destroyed, unusual color development occurred.
(2) The filtration of sample water is conducted continuously by using a filter
paper. The filter paper, after use, tore occasionally. Leakage of water at the filter
sometimes caused entrance of suspended solids into the filtrate. The back flushing
of sulfuric acid caused by back pressure opened holes in the filter paper. Various
attempts are being made to correct these defects, but substantial changes are deemed
necessary.
(3) In order to prevent formation of slime in the tubing, hydrogen peroxide solu-
tion was used for cleaning. But it was discovered that scales, which could not be
removed by hydrogen peroxide solution, were formed inside the mixing coil. As
these scales can be removed by sodium hydroxide solution, hydrogen peroxide
and sodium hydrate solutions are used in turn to clean the tubing. However, alka-
line solution causes unusual color development, so that it takes a long time to restart
the normal operation.
(4) When replacing the pump tube, sample water, containing sulfric acid, back
flowed due to internal pressure and wetted often the operators and the instrument.
3.5 OTHER MEASURING INSTRUMENTS
3.5.1 AUTOMATIC CLEANING UNIT FOR DISSOLVED OXYGEN
ELECTRODE
When measuring dissolved oxygen in the aeration tank, it is important to pre-
vent the formation of slime on the electrode surface. Recently, an automatic clean-
ing system employing air jet was introduced. Fig. 15 shows this new cleaning
system. Type-A unit is designed to measure dissolved oxygen when flow velocity
is insufficient for DO measurement. At measuring time, the air, from the upper air
injection port, pumps up water to accelerate the velocity. And at cleaning time, the
air is injected from the lower air injection port and clean the electrode surface by
vigorous aggitation.
Type-B unit is for the occation that the flow velocity is sufficient for the DO
measurement. It has large openings at the position of the DO electrode for the
water to pass through and has only an air injection port for cleaning.
The effectiveness of this unit has been proved by field tests.
214
-------
Fig. 15 DO Probe with Air Injection Cleaning System
Type A
Air Injection Port
for Air Lift
DO Probe
Air Injection Port ^
for Cleaning
Temp. Signal Cable
Temp. Detector
Air Supply
Air Supply
Sample Suction Port
DO Signal Cable
Type B
/ Cleaning Air Supply
Temp. Signal Cable
Temp. Detector
DO Probe
Air Injection Port
for Cleaning
DO Signal Cable
3.5.2 ULTRASONIC WAVE SLUDGE DENSITY METER
An ultrasonic wave sludge density meter is installed at the Nishiyama Demonst-
ration Plant. The meter, for the past two years, is continuously measuring the
concentrations of primary sludge, excess sludge and return sludge. The sludge
concentration agreed well with those attained by manual measurements. Especially,
good results have been obtain with regard to excess sludge.
However, the variation in the sludge composition seems to pose some problems.
To obtain good results in the measurement of the primary sludge, it is necessary to
increase the frequency of calibration.
3.5.3 SLUDGE LEVEL METER
Sludge level meter, especially ultrasonic-meters, are becoming widely used at
various sewage treatment plants for automatic sludge withdrawal control systems.
215
-------
FIFTH US/JAPAN CONFERENCE
ON
SEWAGE TREATMENT TECHNOLOGY
PAPER NO, 5
STUDIES ON ADVANCED WASTE TREATMENT
APRIL 26-28, 1977
TOKYO., JAPAN
MINISTRY OF CONSTRUCTION
JAPANESE GOVERNMENT
217
-------
STUDIES ON ADVANCED WASTE TREATMENT
I. UPGRADING OF EXISTING SEWAGE TREATMENT PLANTS
BY CHEMICAL ADDITION TO AERATION TANK 220
T. Annaka, PWRI, Ministry of Construction
2. DEVELOPMENT OF DEEP AERATION TANK 237
Dr. N. Okuno, Japan Sewage Works Agency
3. EXPERIMENTAL STUDIES ON PERFORMANCE OF RAPID
SAND FILTRATION PROCESS FOR TERTIARY PURPOSE -249
H. Fujii, Tokyo Metropolitan
S. Kyosai, PWRI, Ministry of Construction
4. EXPERIMENTAL STUDY ON REGENERATION OF GRANULAR
ACTIVATED CARBON 324
S. Ando, PWRI, Ministry of Construction
218
-------
CHAPTER 1. UPGRADING OF EXISTING SEWAGE TREATMENT PLANTS
BY CHEMICAL ADDITION TO AERATION TANK
1.1 Introduction 220
1.2 Outline of Facilities and Testing Procedure 220
1.2.1 Coagulant and Dosing Procedure 222
1.2.2 Sampling and Analysis 222
1.2.3 Automatic Continuous Water Quality Analyzers 222
1.3 Results and Discussion 222
1.3.1 Removal of Phosphorus 225
1.3.2 Nitrification and Nitrogen Removal 228
1.3.3 Acceleration of Nitrification by PH Adjustment 230
1.3.4 Organic Removal 232
1.3.5 Suspended Solid Removal 232
1.3.6 Effects on Microorganisms 233
1.3.7 Material Balance of Sludge Production 234
1.4 Costs of Chemicals 236
1.5 Summary 236
219
-------
1. UPGRADING OF EXISTING SEWAGE TREATMENT PLANTS
BY CHEMICAL ADDITION TO AERATION TANK
1.1 INTRODUCTION
In Japan there are not yet any national water quality standards established for
nitrogen and phosphorus. However, eutrofication is advancing in an increasing
number of lakes, bays and other waters. It is therefore presumed that a substantial
number of sewage treatment plants will be required in the near future to install
themselves with facilities for removing phosphorus, nitrogen. But in our country it
is considered extremely difficult, in many cases, to build additional facilities in the
existing sewage treatment plants due to difficulty in securing tracts of land, although
the situation is different in the case of newly planned plant.
This is the reason why attention is being focused into the method to upgrade
the existing plants by adding metal salts to the existing facilities such as aeration
tank. This method has already been in practical use in the Great Lakes region of the
United States and some parts of Europe. But the situation in Japan is somewhat
different from others; the strength of sewage is weak. On the average, domestic
sewage in Japan contains 150 mg/C of BODS, 3-4 mgP/C of T-P, 30 mgN/£ of T-N
and 100 mg/C of total alkalinity as CaCO3.
The Public Works Research Institute, the Ministry of Construction, in col-
laboration with the Sewage Works Bureau of of Nagoya City, has been operating
Nishiyama Sewage Treatment Plant in the city for two years for experimental pur-
poses. Since then, experiments have been carried out by an addition of alum to the
aeration tank to determine the effect of the alum addition on the entire functions of
the treatment facilities. The results in the initial stage were reported at the previous,
4th conference. This report covers the performance in the ensuing period.
1.2 OUTLINE OF FACILITIES AND TESTING PROCEDURE
The Nishiyama Plant is a relatively small sewage treatment plant adopting
a separate sewer system, having a design daily average flow of 20,000m3/day
(30,000 m3/day at maximum). Since the plant's served area is a residential area,
incoming loadings fluctuate widely at times. There is no recycling of digester super-
natant and other wastes from the sludge treatment facility, because sludge is treated
at a separate plant. The conventional activated sludge process is adopted in the
secondary treatment facility. Two bays - an alum bay and a control bay are used to
compare their performance. There are three final sedimentation tanks. At the first
two months, two of them were used one for the each bay. But they are now being
used in a rather irregular manner - two on one and one on the other, to ensure the
better quality of the plant effluent. The flow chart of the plant is shown in Fig. 1.1
and the dimension of the plant in Table 1.1.
220
-------
Fig. 1.1 Flow Diagram of Nishiyama S-T-P
Grit
chamber
Pre-
aer-
ation
tank
Sewage Sludge
MM Pump
( Pj Flow meter
(SM) Sludge Density Meter
MM Turbidimeter
(M) Point of Continuous
Monitoring for, P, NH3 -N
UV.andTOC.
L —(n (^5MWxl-/f>\--J
Table 1.1 Outline of Nishiyama Facilities
^\ Item
Facility ^\
Grit
chamber
Preparation
tank
Primary
settler
Aerator
Final settler
Type
Rectangular
Diffused
aeration
Rectangular
Diffused
aeration
2 storied
rectangular
Dimension (m)
W L H
2.5 x 10 x 1.85
4.0 x 20 x 3.5
5.0 x 28 x 30
5.0x40x 50x2 bay
«"££'"
Number
2
1
4
2
3
Total
volume
(m3)
245
1,680
4,000
2,250
Design
detention
time
1 .2 min.
1 .3 min.
1.3hr.
3.2 hr.
l.Shr.
Notes: 1. Influent coming in by gravity.
2. Sludge is being treated at the adjacent plant.
221
-------
1.2.1 COAGULANT AND DOSING PROCEDURE
The coagulant used is liquid alum (A12(SO4)3 • 18H2O) containing about 8 per
cent of A12O3. It is dosed at the end of the aeration tank, and the dose rate is
controlled to maintain the concentration of Al at the set level by use of a pro-
portional pump. During the operational period of about 16 months, the dose con-
centration was from 8 to 6, 4, 3 mg/C of sewage in terms of Al (from about 100 to
75, 50, 32 mg/C of sewage in terms of alum). During this period, the concentration
of phosphorus in the primary effluent changed from 2 to 7 T-Pmg/£ in the daily
average. The mole ratio of Al to P also proved to vary widely.
1.2.2 SAMPLING AND ANALYSIS
On a daily base, grab sampling is conducted every one or two hours by auto-
matic samplers and 24 hour composite sample is adjusted in proportion to the flow
rate. Samples are also taken manually as needed. Analyses are made two to four
times a week.
1.2.3 AUTOMATIC CONTINUOUS WATER QUALITY ANALYZERS
The plant is equipped with several types of automatic water quality analyzers
for continuous monitoring of the water quality of both influent and effluent and
controls of the process.
There are ultra-sonic sludge density meters (3 units), TOC meter (1 unit, 6
points), UV meter (1 unit, 6 points), turbidimeters (5 units), phosphorus meters (3
units), ammonia nitrogen meters (3 units), PH meters (6 units) and pre-treatment
units for these analyzers. Their operational performance is reported in a separate
paper.
1.3 RESULTS AND DISCUSSION
The survey has been held continuously since February 1975. The period of
survey, excluding the first two months, can be divided into seven experimental
phases by the rate of alum dose and dosing methods. In Phase II, two of the three
final sedimentation basins were used for control bay, and after Phase III, two of the
three basins were used for alum bay. This switch was made because of a rise of
MLSS in the alum bay which brought about massive solid wash-outs from the final
settler under heavy hydraulic loading period. Summary of operational conditions in
each phase is shown in Table 1.2. In Phase V, alum was dosed at a fixed rate deter-
mined by the daily average flow in order to test the situation under which flow
proportional dose control is not possible. In Phase VIII, the point of addition of
alum was moved from the end point to a point 3/4 of the entire length from the
inlet (20 m from the terminal and about 60 min. in aeration time).
In each phase, efforts were made to maintain MLVSS of the two bays as close
as possible, but this was not necessarily being achieved. Especially in the control
bay, as temperatures went down, activated sludge began getting bulky, raising SS in
the effluent and making it difficult to maintain MLSS of desired level. In general,
MLSS was kept at low levels due to a low strength of sewage and a small capacity of
the final settlers. The summary of the water qualities of influent and effuent in
Phase II, IV, VI and VII is shown in Table 1.3.
222
-------
Table 1.2 Summary of Operation
^•x^--— ^Phase
\\ >o~^~^
\\*
\5^
Item \
Flow rate
(m3/d)
Detention time
(hr)
MLSS (mg/fi)
MLVSS (mg/8)
MLVSS/MLSS
(%)
SV1
BOD load
(kg/kg/d)
SRT (d)
Settling time
(hi)
Over flow rate
(m3/d/m2)
Alum dose
(mg/Al/2)
II
1975.4.1
-9.21
Con-
trol
Alum
11,950
3.0
1,025
719
70.1
94
0.41
3.2
3 6
23.8
-
3.0
912
589
64.6
112
0.46
1.9
1 8
47.6
8
III
9.22-10.19
Con-
trol
Alum
12,550
2.9
1,403
946
67.4
76
0.21
1 7
50.0*
-
2.8
1,002
634
63.3
89
0.29
3 4
25.0
8
IV
10.20-
1976.1.7
Con-
trol
Alum
11,700
3.2
768
620
80.7
115
0.64
3.0
1 8
46.8
-
3.0
1,546
1,000
64.7
72
0.32
3.8
3 6
23.4
6
V
1.8-2.7
Con-
trol
Alum
9,800
3.6
765
673
88.0
136
0.68
2 2
39.2
-
3.4
1,496
1,136
75.9
76
0.35
4 3
19.6
4
VI
2.7-3.31
Con-
trol
*)
Alum
10,900
3.2
631
517
81.8
164
0.75
2.0
20
43.6
-
3.2
1,333
968
72.6
68
0.36
3.1
3 9
21.8
4
VII
4.1-6.30
Con-
trol
Alum
13,075
2.9
743
477
77.5
78
0.59
2.3
1 4
52.3
-
2.9
1,810
1,238
67.0
58
0.25
4.8
2.8
26.2
3
Yin **)
8.23-9.2
Con-
trol
Alum
13,600
3.5
659
432
65.5
96
0.41
2.3
1.5
54.4
-
3.5
1,231
737
59.8
61
0.23
4.3
3.1
27.2
6
*) Constant feed **) Point of dose was changed
223
-------
Table 1.3 Summary of Performance
p
H
A
E
II
P
H
A
E
IV
L'
H
A
s
E
VI
P
ii
A
S
E
VII
PH
Turb.
SS
T-Alk.
T-BOD
S-BOD
T-COD
S-COD
T-TOC
S-TOC
TKN
NH3-N
NO2-N
N03-N
T-P
Ort-P
S-T-P
T-A1
E-Coli
ABS
PH
Turb.
SS
T-Alk.
T-BOD
S-BOD
T-COD
S-COD
T-TOC
S-TOC
TKN
NH3-N
NO2-N
N03-N
T-P
Ort-P
S-T-P
E-Coli
ABS
PH
Turb.
SS
T-Alk.
T-BOD
S-BOD
T-COD
S-COD
TKN
NH3-N
NO2-N
NO3-N
T-P
Ort-P
S-T-P
ABS
PH
Turb.
SS
T-ALK
T-BOD
S-BOD
T-COD
S-COD
T-TOC
S-TOC
TKN
NH3-N
N02-N
NO3-N
T-P
Ort-P
S-T-P
Ecoii
ABS
Unit
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
N/ml
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
N/ml
mg/1
mg/I
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/i
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/I
mg/1
mg/1
mg/1
mg/1
mg/I
N/ml
mg/I
Influent
Ave.
93.8
110
77.3
87
40
59
23
72
30
24.9
13.4
0.034
0.053
3.43
2.14
2.18
0.81
6.51
61.0
128
81.3
133
47
64
20
75
23.
26.0
13.7
0.023
0.25
3.15
1.92
1.71
6.25
98.5
214
92.3
182
62
87
30
29.8
14.9
0.03
0.08
4.43
2.61
2.35
6.46
141
66.8
108
40
61
17
63
20
22.8
10.2
0.07
0.13
3.50
1.67
1.79
4.8
Range
6.88-7.30
67.0-132.0
60-114
60.0-106.5
47-124
26-69
44-90
17-35
39-122
20-51
21.8-28.7
10.2-15.9
0.00-0.28
0.00-0.23
2.14-4.92
1.38-4.15
1.13-3.66
0.56-1.20
5.10-8.50
6.70-7.12
50.0-72.0
90-174
59-104
97-168
39-57
50-83
16-28
42-110
12-32
24.2-34.6
12.0-14.6
0.00-0.05
0.00-0.82
2.06-48.8
1.57-2.10
1.41-2.0
4.6-7.7
7.0-7.27
79.0-120.0
56-471
82-99.5
151-210
48-69
72-120
21-45
25.0-35.5
13.6-15.5
0.01-0.05
0.00-0.23
4.00-5.24
1.97-4.12
2.18-2.58
5.45-7.40
6.87-7.0
96-192
55-80
88-149
23-53
47-76
14-20
53-69
13-24
14.6-32.1
6.0-12.9
0.00-0.22
0.07-0.32
2.92-4.06
1.25-2.03
1.10-2.23
2.5-9.5
Primary Effluent
Ave.
72.0
40
88.7
54
35
43
24
53
28
24.0
13.8
0.009
0.037
3.05
2.16
2.16
0.50
6.06
39.1
42
89.1
79
46
47
22
52
23
23.7
15.0
0.01
0.133
3.00
2.04
1.71
6.37
51.7
45
90.6
82
52
57
30
25.5
16.2
0.04
0.04
3.44
2.11
2.35
5.83
48.7
45
77
68
35
38
18
41
19
20.0
11.7
0.05
0.10
3.04
1.81
1.88
4.4
Range
6.86-7.60
52.0-92.0
36-73
75.5-135
32-95
23-63
27-74
15-30
38-87
16-51
19.9-39.1
10.1-25.5
0.00-0.04
0.00-0.15
2.01-7.90
1.36-4.40
1.22-6.16
0.30-0.80
5.18-7.50
6.86-7.20
36.0-42.1
34-49
79.3-94.5
64-102
38-60
38-60
17-31
25-71
12-32
21.0-28.2
13.2-16.5
0.00-0.02
0.00-0.41
1.86-3.86
1.74-2.39
1.53-1.98
5.4-7.3
7.0-7.18
49.0-54.0
27-54
88-93.5
75-88
42-64
48-76
21-41
21.3-28.8
14.6-18.0
0.03-0.04
0.00-0.13
2.84-3.81
1.89-2.30
2.04-2.86
5.20-6.40
6.90-7.0
28-100
22-84
68-87
62-96
23-48
29-53
13-35
26-48
13-22
14.5-23.0
8.0-14.8
0.00-0.13
0.05-0.15
2.73-3.58
1.53-2.28
1.26-2.51
2.5-6.0
Final Effluent
(Control)
Ave.
8.0
8.5
36.8
10.9
5.1
14.0
10.4
17.6
13.6
10.2
7.1
0.581
4.10
1.51
1.12
1.09
0.26
2700
0.40
8.0
12
55.4
22.7
4.7
12.9
9.1
18.4
9.7
15.0
11.3
0.243
3.03
1.93
1.17
1.32
5100
0.67
8.5
16.2
87.5
16.3
5.3
15.3
9.6
23.1
14.8
0.06
0.20
1.83
1.60
1.51
0.59
10.5
13
46
26
7.2
13.8
8.6
13.9
9.5
11.9
8.0
0.29
1.99
1.68
1.11
1.12
1800
0.54
Range
6.26-7.60
4.1-11.3
6.2-12.4
12.0-95.0
6.5-19.5
2.9-8.4
9.3-16.4
5.1-14.6
12.0-36
9.4-29.5
5.0-21.0
2.8-17.4
0.06-1.26
0.19-8.50
0.67-3.21
0.59-1.97
0.46-2.40
0.25-0.30
200-9600
0.22-0.58
6.50-7.10
7.6-9.5
6-20
23.4-84.5
1 12-28
2.2-6.4
10.1-15.1
6.8-10.8
6.2-34
4.3-15.0
6.9-20.2
5.4-15.3
0.12-0.30
0.18-6.45
1.29-2.73
0.18-1.58
1.05-1.47
2500-7000
0.25-0.90
7.06-7.23
5.7-7.0
6.8-32.0
82-94.5
12.1-23
4.7-5.8
12.9-21
7.5-12.7
15.1-30
13.4-17
0.02-0.10
0.00-0.32
1.63-1.9
1.43-1.82
1.35-1.61
0.52-0.66
6.65-6.96
3.4-50.3
4-21
30-69
14-34
6.3-8.8
11.2-16.7
6.8-10.5
11-17
8.3-10.9
8.6-17.9
5.2-13.7
0.22-0.54
0.10-3.89
1.13-2.27
0.36-1.74
0.18-1.82
480-4500
0.26-0.99
Final Effluent
(Alum)
Ave.
7.4
15.0
31.7
7.0
3.4
9.8
6.6
13.4
10.5
16.4
13.1
0.086
0.653
0.355
0.185
0.087
0.86
2000
0.68
4.1
4.7
48
4.5
2.8
7.9
6.1
10.9
6.6
17.1
14.5
0.035
0.488
0.168
0.093
0.045
500
0.575
5.3
13.9
73.8
8.5
4.7
12.4
8.6
20.0
15.9
0.06
0.16
0.52
0.27
0.19
1.34
6.8
11
61
12
6.1
12.3
7.2
10.8
15.2
10.7
0.09
0.71
1.09
0.61
0.40
840
0.58
Range
6.62-7.3
4.9-11.6
4.0-57.0
13.5-42.5
3.6-12.8
1.3-5.2
8.2-18.9
5.1-11.1
8.0-22.3
7.7-21.0
9.8-20.3
10.0-16.4
0.01-0.32
0.12-1.41
0.14-0.69
0.06-0.60
0.02-0.25
0.39-1.30
180-8500
0.30-1.30
6.70-7.02
3.2-5.0
0.2-12.3
40-56
2.5-6.9
1.9-4.6
6.2-10.6
4.7-6.9
4.0-17.0
3.5-9.0
14.2-20.4
12.3-16.5
0.02-0.08
0.07-0.83
0.14-0.21
0.05-0.19
0.01-0.09
30-1800
0.24-0.80
7.07-7.10
3.7-7.0
6.0-28
67.5-82
7.4-9.3
4.3-4.9
10.4-19
5.7-13.1
15.2-24
13.9-18
0.03-0.09
0.00-0.25
0.37-0.72
0.09-0.69
0.03-0.29
0.84-1.76
6.73-7.04
2.2-28.1
6-13
50-67
6-16
5-8
10.5-14.1
6.3-8.6
9.0-12.0
11.0-20.3
7.6-14.5
0.08-0.22
0.11-1.27
0.53-1.96
0.17-1.45
0.02-1.53
200-1800
0.3-0.78
Removal Eff.
Over Secon-
dary (%)
88.9 89.8
80.0 87.2
85.3 91.2
67.2 77.0
57.4 73.0
67.0 74.9
50.0 62.1
57.5 61.7
48.6 5.1
50.5 88.4
48.2 91.5
49.6 96.0
93.4 88.8
78.1 89.6
71.1 94.3
71.1 94.3
89.7 95.9
72.6 83.2
50.5 72.2
64.7 79.1
57.5 71.9
32.8 27.9
24.7 3.4
35.4 34.4
42.7 95.5
22.9 97.4
89.5 91.0
85.6 89.8
80.1 79.6
89.9 91.1
73.1 70.2
67.6 71.0
9.5 21.6
8.7 1.9
46.9 84.9
24.2 87.3
35.8 92.0
89.9 77.1
78.5 86.1
71.1 75.6
61.8 82.4
79.5 82.6
63.7 64.9
52.3 60.0
66.1 73.7
41.5 24.0
31.7 9.6
44.8 64.2
38.7 66.3
51.5 79.8
87.8 86.9
224
-------
1.3.1 REMOVAL OF PHOSPHORUS
a. Phosphorus Removal and Mole Ratio
Phosphorus removal rate is raised drastically by an addition of alum. Table 1.4
shows the phosphorus removal efficiency in each phase. Fig. 1.2 shows relationships
between the mole ratio of dosed Al to soluble phosphorus and residual phosphorus
in effluent.
Table 1.4 Summary of Phosphorus Removal
~r - — — -____ Phase
Item — .
Primary Eff. T-P (mg/£)
Primary Sol. T-P (mg/£)
A£ Dose (mg/£)
A£/P Mole Ratio (T-P Base)
A£/P Mole Ratio (ST-P Base)
Effluent T-P (mg/£)
Effluent Sol. T-P (mg/fi)
II
3.05
2.16
8
2.98
4.25
0.355
0.087
III
2.15
1.28
8
4.25
7.18
0.27
0.09
IV
3.00
1.71
6
2.29
4.03
0.168
0.045
V
3.04
1.95
4
1.49
2.35
0.53
0.17
VI
3.44
2.35
4
1.38
1.95
0.52
0.19
VII
3.04
1.99
3
1.16
1.74
1.09
0.40
VIII
2.29
1.52
6
3.01
4.53
0.42
0.03
Note: All values are average through the each phase.
Fig. 1.2 Residual Phosphorus V.S.
AI/P Mole Ratio (S-T-P Base)
I.O
"SB
&
ST 0.5
oT-P
• Sol. T-P
345
Mole ratio
7 (Al/P)
The residual phosphorus is 0.5 mgP/£ in T-P and below 0.2 mgP/£ in soluble
T-P in phases other than Phase VII in which the mole ratio was low. Fig. 1.2 shows
that if the mole ratio is above 2 (Al 4 or alum about 50 mg/£), effluent soluble
phosphorus can be decreased below 0.2 mg/£.
225
-------
The residual phosphorus is 0.5 mg P/l in T-P and below 0.2mg P/l in soluble
T-P in phases other than Phase VII in which the mole ratio was low. Figure 1-2
shows that if the mole ratio is above 2 (Al 4 or alum about 50mg/l), effluent
soluble phosphorus can be decreased below 0.2mg/l.
Effluent PH varies with the rate of alum addition in the range from 6.6 to 7. It
is not wise to dose alum at a mole ratio of more than 4, since the solubility of
A1PO4 is 0.01 mgP/C at PH6 and 0.3 mgP/C at PH7. However, as for total phos-
phorus removal a higher mole ratio seems to be effective in regards to floe forma-
tion. In the treatment of domestic sewage in our country where the daily average of
phosphorus concentration is 3 ~ 4 mgP/C, an alum dose rate of 50 ~ 70 mg/£ would
be enough to lower T-P below 0.5 mg/£ and soluble phosphorus 0.2 mg/£. Inci-
dentally, at this particular sewage treatment plant, the phosphorus removal rate in
the control bay is rather high with 40% ~ 50% probably due to a luxury uptake of
bio-mass.
b. Phosphorus Removal Capability of Return Sludge
By an alum addition, the return sludge proves to remove (absorb) a substantial
amount of phosphorus from the influent. Fig. 1.3 shows a comparison of hourly
changes in the phosphorus concentration of superatant of the mixed liquer immedi-
ately after return sludge was mixed with the influent in both control and alum bays.
Fig. 1.3 Diurnal Change in ST.P. of Mixed Liquor Supernatant
Control
Alum
18 (hr)
(Phase IV) In this instance, a contact with return sludge removes about 80% of
phosphorus. This is considered to be absorption of aluminum hydroxide contained
in return sludge. Fig. 1.4 shows the results of a jar test in which the mixing ratio
of return sludge and influent was changed in order to ascertain phosphorus removal
capability. As the mixing ratio is raised, as shown in the figure, the rate of removing
soluble phosphorus from the superatant will increase, and the removal rate reaches
90% when MLSS is above 3,000 mg/C (Al concentration of sludge 10% Al/TS).
226
-------
A similar test was conducted using alum sludge yielded in the water purification
plant. Aluminum in sludge was 12.5% Al/TS. Fig. 1.5 shows the results of the jar
test. As in the case of return sludge, a high phosphorus removal rate is attained with
the alum sludge of the purification plant. This indicates an important role that alum
sludge could play in removing phosphorus within the treatment process.
Fig. 1.4 P Removal Capability of Return Sludges
100 .
-a
E
£ 50 -
o
O Return sludge (Alum bay)
• Return sludge (Control)
A Alkalinity (Alum)
Initial?: 1.8mg/S
1,000
2,000
MLSS(mg/S)
3,000
Fig. 1.5 P Removal Capability of
Alum Sludge Yielded at Water Plant
i oo
50-
0 S-P removal rate
Initial?: 1.39 mg/e
-7.0
-6.0
1,000
2,000
3,000
MLSS (mg/2)
227
-------
Similar phenomena are observed in the pilot plants in Yokosuka and Kyoto
treating secondary effluent with alum. They have stably attained a high phosphorus
removal rate by returning sludge to the head of the plant.
As earlier stated, in Phase IV alum was dosed not in proportion to the inflow
but a constant rate. As shown in Table 1.4, there seems little difference in phos-
phorus removal efficiency between flow proportional feed control and constant feed
of alum. This indicates that the "secondary" phosphorus removing capability perti-
nent to return sludge plays an important role in overall phosphorus removal. In
adding alum to the aeration tank, it would be more efficient and costly to use waste
activated sludge from the alum bay for return sludge in other bays.
The Nishiyama plant is in the initial stage of practicing the mole ratio feed
control by use of signals from automatic continuous phosphorus analyzers. If the
phosphorus removal rate is determined by the mole ratio of phosphorus in the super-
atant of mixed liquer at the point of addition, phosphorus removal capability of re-
turn sludge could be significant and affect the mole ratio feed control itself when
influent phosphorus concentration is used as a base of P.
1.3.2 NITRIFICATION AND NITROGEN REMOVAL
In this project, removal of ammonia nitrogen by nitrification is just as import-
ant an objective as well as removal of phosphorus.
Fig. 1.6 shows changes in ammonia nitrogen, nitrite and nitrate in effluent
of both bays as observed during a period from March 1975 to July 1976.
Fig. 1.6 Change in Nitrogen in Final Effluent
30-,
5-
Water temp.
' fN02+N03)-N, control |j V >A
Mar. Apr. May June July Aug. Sep. Oct. Nov. Dec.
1975
Feb. Mar.
1 1
Apr. May June July
1976
228
-------
SRT was maintained in the range of 2 ~ 5 days. In both bays nitrification did
not take place in winter when temperature was low, probably because SRT was
not enough. In Phases II ~ IV in which temperatures were above 20°C, substantial
nitrification took place only in the control bay, while nitrite and nitrate nitrogen
was slightly observed in the alum bay.
The absence of nitrification in the alum bay has been discussed from various
angles; first, SRT required to maintain nitrifiers; second, interference of aluminum
on the activity of nitrifiers; and third, depletion of alkalinity.
As to the interference of aluminum on nitrification, batch type laboratory
tests show that an addition of 10 mgAl/£ (120 mg/C of alum) causes no noticeable
affect.
The fact that in Phase VII in which SRT is maintained higher (4.8 days), nitrifi-
cation took place even in the alum bay seems to indicate that SRT has a large effect
on nitrification, in conjunction with the effect of temperature. This, however, seems
to have some relationships with a relatively low alum dose rate, which means a low
consumption of alkalinity by alum addition. The nitrification of Nl consumes al-
kalinity by 7.1 (as CaCOs). The influent of this plant shows an daily average T-N
value of more than 25 mgN/£ and the alkalinity is a high 80 mg/£. Complete nitrifi-
cation, therefore, could not be expected without an addition of alkalis, even if other
conditions are satisfactory.
Fig. 1.7 shows how the nitrogen, the PH and the alkalinity of the superatant
of the mixed liquid will change as it flows down through the tank in the alum bay
(Phase VII). In this instance of low loading night hours, the concentration of
ammonia nitrogen is low. But complete nitrification does not take place as alkalinity
is consumed by nitrification and alum addition.
Fig. 1.7 Change in Supernatant Quality in the Aerator
(Alum Bay)
O PH
• T-alkalinity
A NH3-N
O (N02 +N03)-N
Flowing time in aerator (hrs)
Alum Outlet
dose
229
-------
Thus as in the case of non-chemical addition, the lowering in water temper-
ature causes a problem in nitrifying the effluent in the alum bay, as shown in Fig.
1 6 Therefore to keep desirable SRT is a major factor in conjunction with the
capacity and structural improvement of the final sedimentation basin. It is also clear
that complete nitrification cannot be achieved without adding alkalis in place where
alkalinity is low, like the domestic sewage treatment of our country.
In the case where nitrified effluent is obtainable, it is known that fine scum
appears to the surface of the final settler as a result of the generation of nitrogen
gas by denitrification at the bottom of the settler. Through the experiment, it was
observed during the nitrificastin in the control bay. An experiment in resettling
by spraying of the effluent has been conducted. Since scum often flows out with the
effluent, the installation of a scum collector is under consideration.
On the other hand, in Phase VII in which nitrification took place in the alum
bay, the scum as mentioned above does not float at all and the surface of the settler
is clear in the final settler, even if the level of oxidized nitrogen in the effluent is
the same as that in the control level. There seem to be factors hampering denitrifi-
cation in the alum dosing process.
In ordinary cases, at the plants where ntrification is taking place, there appear
differences between the inflow and outflow of T-N, which results in a relatively high
T-N removal rate probably due to denitrification. The T-N removal rate is generally
lower in the alum bay than in the control bay even when same degree of nitrifica-
tion is taking place. This is considered to have something to do with preventing the
floating of scum.
1.3.3 ACCELERATION OF NITRIFICATION BY PH ADJUSTMENT
As mentioned earlier, when alum is added, it consumes alkalinity and prevents
complete nitrification. Therefore, alkalis, such as sodium hydroxide and lime, need
to be added in order to remove phosphorus and nitrify the effluent simultaneous-
ly in the system. There, it is difficult to use lime because of scale formation in pipes
and other places. Therefore, sodium hydroxide will probably be better to be
adopted for the purpose.
A bench scale laboratory test was conducted prior to the addition of sodium
hydroxide to the main plant. About two months of operation demonstrated that it
is possible to obtain an almost completely nitrified effluent by adding alum at the
end section of the tank and sodium hydroxide at the inlet. Table 1.5, 1.6 show the
operating conditions of the bench scale plant and the qualities of the influent and
effluent. Almost complete nitrification and a T-N removal rate of about 70% are
achieved by maintaining SRT at 8.2 days and PH at the inlet at 8.2. The problem of
this process seems to be a somewhat low phosphorus removal rate due to rises in the
PH of the effluent.
Table 1.5 Summary of Bench Scale Plant Operation
Flow
(m3/d)
2.5
Al Dose
(mg Al/B)
= 4
Adjusted
PH
8.2
MLSS
(mg/C)
3.030
BOD Load
(kg/kg/d)
0.17
SRT
(d)
8.2
230
-------
Table 1.6 Summary of Bench Scale Plant Performance
Inf.
Efl.
Average
Range
Average
Range
PH
6.6-7.2
7.3-7.6
T-alkalinity
(mg/ECaCO3)
66
57-104
93
88-102
SS
(mg/E)
38
13-117
14
9-20
COD
(mg/E)
39
25-73
8
6-15
TKN
(mg/fi)
16.7
12-30
1.45
1.1-1.7
NH3-N
(mg/E)
8.3
6-11
0.26
0.14-0.40
NO2+NO3-N
(mg/8)
0.05
0-0.9
2.96
2.8-4.2
T-P
(mg/E)
2.66
1.56-5.15
0.78
0.5-1.2
The addition of sodium hydroxide to the actual facilities began in mid
December 1976. Since the aeration tank is of a conventional plug flow type, the
caustic addition is controled at two points. One point is immediately after the mix-
ture of the influent with return sludge and the other at the middle section of the
tank. Fig. 1.8 shows PH controls chart.
Fig. 1.8 PH Control Diagram
/NaOH\
V tank J
O
z
Control /T_3
valve ^T^
7
i
Controler
t
PH meter
-f
L
r
\
Control valve
i£ NaOH
Buffle
Aeration tank
(S PH meter . .
v-' (1st point)
"~j Influent conduit
PH meter
^^ Moved point
f
^C
)
-••
O "" —
(2nd point)
PH meter
PH meter
About six weeks have passed since the caustic addition began. The average
MLSS concentration within the tank has kept 3,500 mg/5 (SRT approx. 8 days).
The dose rate of alum is 8 mg/C in terms of aluminum. The addition of sodium
hydroxide (20% solution of NaOH) is controlled to raise PH at the first adjustment
point up to 7.8 ~ 8.0. At the present stage, nitrification has not taken place as
originally expected, because the water temperature is low - 10° ~ 12°C and acclima-
tion to change in PH is insufficient.
Two problems have occurred as to the PH adjustment at the actual facilities.
One problem is that PH rises momentarily to about 12 in limited portions around
the inlet. The second problem is that as a result of this, a sticky foam substances
appears to the surface of the aeration tank and that scum forms on the surface of
the final settler.
231
-------
The dose of soidum hydroxide is controlled using PH meters in the way that
the dosing pump turns on at the set upper value (8.0) and turns off at the lower
value by the signals of PH meters and that the dose rate is proportional to the in-
flow. There is a 15-minute time lag between the dose of sodium hydroxide and the
response of the PH meter. This has been found to allow the dose of surplus sodium
hydroxide and raise PH around some portion of the inlet up to 12.
A separately conducted indoor experiment shows that as PH exceeds 11, nitro-
gen in activated sludge resolubilizes and foam formation develops. Also at the batch
test using return sludge of this treatment plant, as the PH of return sludge was raised
to 12 organic substances in activated sludge resolubilizes into the superatant, such
high concentration as TOC of l,OOOmg/C and poly-saccharide of 600mg/£. Thus,
it was considered that this might have been the reason of upset of the entire process.
As a result, the point of sodium hydroxide addition was moved to the upper
end of the influent waterway (approx. 40 meters); the method was changed to ad-
just PH at the tank inlet; and the outflow of the dosing pump was changed to a
constant rate.
1.3.4 ORGANIC REMOVAL
The addition of alum raised removal rates for BODs, TOC and COD. To com-
pared with control bay, the removal rate for BODs rose by 30%~80%, that for COD
20% ~ 40% and that for TOC 30% ~ 40%. Similar results were attained for the re-
moval of soluble organic substances.
1.3.5 SUSPENDED SOLID REMOVAL
In Phase II, effluent SS was higher in the alum bay. But it outrated that of the
control bay after Phase III in which two final settlers were used. The debris of al-
uminum hydroxide floe tends to flow out more easily, in addition to rises in solid
loading in the final settler. Therefore, it is necessary to provide a lower overflow rate
than the ordinary design value. It is observed that as the alum dose rate is lowered,
the density of the effluent SS tends to increase; this is probably because a decline
in the dose rate will aggravate coagulation.
In Phase VIII in which the point of alum addition was moved to a point 3/4 of
the entire length (20 meters from the end), the effluent became a little bit milky
white as time passed, although there were no noticable differences in the SS value
between this and other phases. The change in the effluent colour has already been
reported in other studies. As reported in some of them, it seems to be reasonable to
assume that this has something to do with the point of alum addition. It is consider-
ed that a deflocculation caused by over-aeration after alum addition has a signifi-
cant effect on this because such a phenomenon did not take place at all in experi-
ments in which alum was dosed from the end point.
Table 1.7 is a comparison of the composition of condensed these substances
and that of solids in effluent from the control bay.
In the control bay, substances of obviously different quality compared with
activated sludge flows out, but in the alum bay, activated sludge including alumi-
num itself comes out in broken-up form.
232
-------
Table 1.7 Component of Solids
VSS/TS (%)
TKN/TS (%)
T-P/TS (%)
A2/TS (%)
SS in Eff.
(Control)
49.2
3.79
0.61
0
Return Sludge
(Control)
70.0
7.28
2.95
1.74
SS in Eff.
(Alum)
40.8
6.75
2.96
7.65
Return Sludge
(Alum)
63.0
5.85
3.14
8.10
1.3.6 EFFECTS ON MICROORGANISMS
The effects alum have on activated sludge protozoa have been discussed from
many angles.
In this project, survey was conducted from two points. One is the microscoptic
examination of activated sludge protozoa. The other is the measurement of dehydro-
genizing activity, which is considered to have relationships with the metabolic activi-
ty of micro-organisms.
Fig. 1.9 is the comparison between the two bays of the dehydrogenizing
activity of activated sludge when 8 mg/C of aluminum was added. It shows hourly
changes at different points in the aeration tank. Dt on the figure shows total activi-
ty. De shows activity after substrates are washed out (that of eudonegous respira-
tion) On the control side, Dt is always higher than De, while De is higher on the
alum dose side. In other words, activity rises after substrates are washed out. There
is little difference in the De value between the two bays. This indicates that the
addition of 8 mg/£ of aluminum is interferring biological activities in one way or
the other. Similar phenomena are often observed in sewage treatment plants where
relatively large volumes of industrial waste flow in.
Fig. 1.9 Comparison of Dehydrogenaze Activity
(Al 8 mg/8)
o Inlet (Alum) • Inlet (Control)
o % point (Alum) •% point (Control)
A Vi point (Alum) A ^ point (Control)
D Outlet (Alum) • Outlet (Control)
12 14
Time (hr)
233
-------
As for changes in protozoa, the numbers of spieces and population proved to
decline in the alum bay comparing to the control bay when the concentration of
added aluminum was high. Fig. 1.10 shows monthly changes in the population of
total ciliata and activated sludge ciliata per unit of MLSS in both bays. Although
alum addition reduces the population, the dgree differs with the dose rate of
aluminum. There is little difference between the two bays when aluminum is below
4 mg/£ (below 50 mg/C as alum). Thus, it seems to be possible to assume that there
is little practical effect on protozoa when added alum is below 50 mg/£. As mention-
ed earlier, this dose rate is also effective for phosphorus removal.
Fig. 1.10 Comparison of Ciliata Number in Activated Sludge
Activated sludge cilita
Total cilita
Control
00
Is
p.
"
T
1975
1976
H h-
May June July Aug. Sep. Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June (Month)
Alum dose AS 8 mg/8
6mg/C
Smg/C
Alum addition would considerably reduce the population of swimming type
ciliata (difference between total ciliata and activated sludge ciliata). But it is not yet
clear - whether the reduction is a direct effect of aluminum or it is a result of the
change in environment by advanced removal of organic substances.
1.3.7 MATERIAL BALANCE OF SLUDGE PRODUCTION
It is known that an increase in sludge production is a one of the most trouble-
some problems in the process. In this plant, continuous monitoring of primary
sludge and waste activated sludge is being conducted in both control and alum bays
to determine the material balance of sludge production. Sludge production is
measured by electro-magnetic flow meters and solids by ultra-sonic sludge density
meters.
234
-------
The increase in sludge production by alum addition is theoretically calculat-
ed by the amount of AlPOa produced by the coagulation and Al (OKQa by hy-
drolysis. There is also the transfer of organic sludge as in the control bay.
Table 1.8 is the summary of daily influent loadings and primary sludge in daily
average monitored by each phase during the whole experimental period. Shown on
the Table is the material balances of sludge production of added aluminum of 8, 6,
4, 3 mgAl/C.
Table 1.8 Comparison of Sludge Production
"^ ____Phas
-------
1.4 COSTS OF CHEMICALS
According to the purchase prices in Nagoya City, alum is 21 ¥/kg in terms of
14.5% AHOs (¥273 per kilogram of aluminum). The chemical cost required is
2.19¥/m3, 1.64¥/m3 and 1.09¥/m3 respectively when the rate of added alum is
100 mg/C, 75 mg/C and 50 mg/C.
Sodium hydroxide is ¥61.3 in terms of one kilogram of NaOH, which means
1.23¥/m3, 2.45¥/m3 and 4.9¥/m3 respectively when the alkalinity addition is
25, 50 and 100 mg/C (as CaCO3).
Aluminum consumed in Japan is almost entirely imported from abroad. There-
fore, the cost is rather high compared with other countries and its unit price is un-
stable. These are the factors that should be taken into account in using aluminum
salts as coagulants. The situation is generally the same for iron salts. Therefore, it is
strongly considered necessary to recover the used eoagulants from sludges and the
projects is now underway at the laboratory experiments.
1.5 SUMMARY
The following has been obtained through a series of experiments in which
alum was added to the aeration tank treating typical domestic sewage in Japan,
which is relatively weak strength.
1) When phosphorus contained in the influent is below 3 ~ 4 mgT-P/£, an alum
addition of 50 mg/C reduces the residual phosphorus to less than 0.5 mg/C.
2) The phosphorus removal capability of return sludge is sufficient enough to be
taken into account in controlling alum dose.
3) It is possible to botain nitrified effluent while removing phosphorus. But in the
case of a sewage of low alkalinity like one in Japan, it is necessary to add alkalis.
4) Adequate care should be taken in determining the method to dose alkalis to
the aerator.
5) The alum addition of 50 mg/C has little practical effect on activated sludge
protozoa.
6) The increase in sludge production varies with the alum dose rate, and in this
particalr studie increase rate was about 60%.
236
-------
CHAPTER 2. DEVELOPMENT OF THE DEEP AERATION TANK
2.1 Introduction 238
2.2 Overall Oxygen Transfer Coefficient vs. Power Consumption 239
2.3 Variation Range of DO Concentration in Mixed Liquor Due to
Influent BOD Change 240
2.4 Separation of Bio-Mass from Liquid in Final Clarifier 241
2.5 Design and Operation of Full Scale Deep Aeration Tank in Tokyo 244
2.5.1 Design Parameter 244
2.5.2 Distribution of Suspended Solids and Stream Velocities 245
2.5.3 Performance and Economical Feasibility 245
2.5.4 Construction Costs 246
2.6 Comparison of Diffuser and Jet Aerator in Deep Aeration Tank 246
237
-------
2. DEVELOPMENT OF THE DEEP AERATION TANK
2.1 INTRODUCTION
Because of the high prices of land, and the opposition from local inhabitants, it
has become almost impossible to purchase new sites for sewage treatment plants
within the large cities. And it is proving to be just as difficult to extend facilities at
existing plants. Despite this, however, an amount of wastewater and requirements
for high purification of wastewater are increasing all the time. The only alternatives
left are to go upwards, or go down under the ground. The deep aeration tank is
an example of this latter alternative.
A main advantage of increasing the depth of aeration tanks is (1) greater tank
capacity within the limited space available. Addition to this (2) higher MLSS con-
centrations attainable because of the larger saturated concentration value of dis-
solved oxygen in mixed liquors, and (3) less variation range of dissolved oxygen
concentration are expected. (2) and (3) are no more than theoretical predictions at
present.
In both Japan and the USA, the standard effective depth of aeration tanks has
been 4.5 ~ 5.0 m. The 1975 ASCE Manual No. 36 states that "Ordinary liquor depths
will not be less than 10 feet nor more than 15 feet. The depth is governed in part by foundation
and construction costs, in part by the size of the tanks.", while Babbit (1960) adds that
"Practice and experience in the United States have led to the adoption of a depth of about 15 ft
as representing an economical balance between structural cost and operating cost. A greater
depth, to about 20 ft, would give greater efficiency of aeration, but the cost of the tank would be
increased, and the higher compression to which the air would be subjected would increase the
operating cost. Tanks shallower than about 15 ft would decrease these items but the efficiency of
aeration would be uneconomically reduced and the land area required would be proportionally
increased. " Since then, aeration tanks have always been constructed with depths of 4
to 5 m. It is not exactly clear what happen being associated with the deeper tanks.
The adoption of deeper aeration tanks poses many questions:— (1) would
there be sufficient generation of the micro-organisms active for sewage purification,
(2) would these micro-organisms settle properly in the final clarifier, and (3) how
economical would the running costs of such a deep tank be, etc. In order to answer
these and other questions, a pilot plant was set up in 1972, prior to construction of
any full scale plants. An outline of this pilot plant is shown in Fig. 2.1.
238
-------
Fig. 2.1 Schematic Flow Sheet of Pilot Plant
Compressor
Spray
Measuring weir
Influent
channel
Clarifier
010.0 m x H 3.0m
V = 237m3
Outfall
Deep aeration tank
^04.0 m x H 18.0m
V = 226m3
2.2 OVERALL OXYGEN TRANSFER COEFFICIENT VS. POWER
CONSUMPTION
The relationships between Ki^V and water depth, and Kj^V and air flow rate
(based on data from the pilot plant) are shown in Figs. 2.2 and 2.3 respectively.
Fig. 2.2 Depth vs. KLa
2,000
1,000
,-, 500
.c
"e
> 200
03
100
50
6 8 10 20
H (m)
Fig. 2.3 Air Rate vs. KLa-V
2,000 - B
1,000
500
200
100
50
40 60 80 100
Gs(Nm3/hr.)
200 300
239
-------
Water depth and air flow rate are mathematically related to Ku by the follow-
ing expression,
KLaV = K"'Gs(1-m)H(1-n) (1)
From the data, equation (1) is changed to equation (2).
KLaV = 0.085 GsL38H°-72 (2)
It is clear that the overall oxygen transfer coefficient will be proportional to
water depth raised to the 0.72 power.
The amount of power required for air diffusion is given by the following
expression: —
L = K-H°-67 (3)
A comparison of expressions (2) and (3) above will show that the increase in
power requirements due to the deep air diffusion, is more or less offset by the
increase in oxygen transfer efficiency; That is, there is little loss of economy caused
by the lower diffuser location.
2.3 VARIATION RANGE OF DO CONCENTRATION IN MIXED LIQUOR
DUE TO INFLUENT BOD CHANGE
Changes in the influent BOD concentration will result in changes of the oxygen
uptake rate (that is, dissolved oxygen concentration) in the mixed liquor. Variation
in mixed liquor dissolved oxygen concentration, Ac, is related to the oxygen uptake
rate, AyT by the following expression: —
K
(4)
La
And since the value of KLS is larger in deeper aeration tanks, Ac will be smaller
for a given Ayr. In other words, there should be smaller variations in dissolved
oxygen concentration for the deep tanks. In Fig. 2.4, observed values of mixing
Fig. 2.4 DO in Mixed Liquor
15.0 r
10.0 -
5.0
1.0
18m depth
Aye.
F/M
MLSS 1250mg/C
Air rate 380 ms/hr.
B • 5m depth
_Ave.
F/M 103
MLSS 700 ms/C
Air rate 350 nr'/hr.
0 04 8 12 16 20 24
Time
240
-------
liquor dissolved oxygen concentrations are plotted for a 4 m, and an 18 m tank.
The amount of variation in the 18 m tank is clearly less (about half) than in the 4 m
tank, thus giving proof to the theoretical considerations.
2.4 SEPARATION OF BIO-MASS FROM LIQUID IN FINAL CLARIFIER
Active bio floe was pumped from an existing aeration tank to the 18 m pilot
aeration tank. At beginning the concentration of suspended solids in the mixed
liquor was observed about 800 mg/C. However, within 20 hours after commencing
operation, the MLSS in the pilot aeration tank had fallen to 200 mg/C.
The bio floe had been carried out with the effluent, since it did not without
settle in the final clarifier. There was bio floe floating on the surface on the final
clarifier (see Fig. 2.6).
800
__ 600
Is
« 400
S
200
Fig. 2.5 MLSS vs. Time
Fig. 2.6 Floated Sludge on the Surface
of Final Clarifier
0246 8 10 12 14 16 18 20 hr.
Time after starting up
This bio floe accumulated behind the scum baffle, and finally flowed over the
weir. But once this problem is solved, the deep aereation tank will be ready for
practical use.
Fig. 2.7 shows how a sample of mixed liquor, taken from the above pilot
aeration tank, changed over a period of time. The bio floe did not float to the sur-
face immediately after a sample of mixed liquor was poured to the cylinder. Instead,
the sludge particles agglomerated together over a certain period of time, and once
they reach several millimeters in size, they quickly rose to the top. This rising floe
was found to have small air bubbles adhering to it (see Fig. 2.8).
Fig. 2.7 Floating Sludge with Time
Fig. 2.8 Floe with Adhering Air Bubbles
-------
A special analysis proved that the air bubbles contented a high nitrogen.
Nitrogen in the air which was diffused into the mixed liquor at a depth of 18m
dissolved up to saturating the liquor with nitrogen. But since the saturated nitrogen
concentration near the surface is lower, the excess dissolved nitrogen reverts to the
gaseous state, forming small bubbles of gas.
Next, a sample of mixed liquor was taken from an aeration tank where the
diffuser was located at a depth of only 4 m. The floe behaviour was again examined
(see Fig. 2.9).
Fig. 2.9 Floe Behaviour (in 4 m Aeration Tank)
In this case, the floe settled very well. This illustrated very clearly the close
relation between diffuser position and floe floating/settling behavious.
In order to purge the floe of the adhering bubbles, re-aeration of the mixed
liquor was tested. All of the mixed liquor from the 18m aeration tank was flowed
through a series of four 4.5 m re-aeration tanks, and re-aerated for 40 minutes (10
mins. in each tank). Samples were taken from each tank, and allowed to rest for 30
min. The degree of settling in each case has been shown in Fig. 2.11.
Fig. 2.10 Reaeration
i I
Fig. 2.11 Effects of Reaeration
I inal tank,.
I inal clarificr
10 0 m* x 30 mH
2.0m
Rcaerution tank
2.0 in x 1.0 m xS.O m x4 = 40 m'
rif ~
— Air
•"- Raw waste
~ Return sludge *^ ~- ,
GL + 0.8 m
242
-------
The results revealed that re-aeration for 20 minutes was sufficient to prevent
the floe from rising to the surface. Table 2.1 listed the concentrations of dissolved
oxygen, nitrogen, and carbon dioxide in the mixed liquors of each tank. A com-
parison of this table with Fig. 2.10 indicated that the floe started to rise when the
nitrogen concentration exceeded 20 mg/B. Special attention should be paid to the
fact that it is possible to prevent floe from rising without reducing the dissolved
Table 2.1 Dissolved Gas Concentration Observed
Location
18m Depth
#1 Re-Aeration Tank
#2 Re-Aeration Tank
#3 Re-Aeration Tank
#4 Re-Aeration Tank
Standard Aeration Tank
02 (mg/fi)
12.7
12.0
8.8
9.4
8.3
8.2
7.8
8.6
8.7
9.3
3.2
N2 (mg/B)
27.9
26.4
22.3
22.1
20.4
19.8
19.0
18.8
18.9
19.3
18.3
C02 (mg/B)
30.1
31.6
-
16.0
-
27.7
-
23.2
-
21.0
44.4
nitrogen concentration as low as the saturation level (14.9 mg/B) under atmospheric
pressure. This threshold concentration of 20 mg/B corresponded to the saturated
concentration of dissolved nitrogen at a water depth of 5.8 m. The aeration depth,
5 m, which has traditionally been a standard has a meaning, although they do not
understand significance of the meaning. The 5 m are the depth in which bio floes
are free from floating, since disolved nitrogen concentration in the depth is a bit
inside the threshold.
243
-------
2.5 DESIGN AND OPERATION OF FULL SCALE DEEP AERATION TANK
IN TOKYO
2.5.1 DESIGN PARAMETERS
A deep aeration tank has been installed at the Morigasaki Sewage Treatment
Plant in Tokyo. Since this area is reclaimed foreshore, the ground is still not very
firm, making it difficult to excavate beyond 10m. Consequently, the effective
depth of this tank is 10m. And in order to prevent floatation of the bio floe, the
diffuser has been set half way down the tank. A cross-sectional diagram of the tank
is shown in Fig. 2.12.
Fig. 2.12 Cross Section of Full Scale Deep Aeration Tank
The baffle plate running down the center of the tank has been installed to assist
the mixing. The design criteria are as follows:
Influent flow rate:
Influent BOD:
Dimensions of aeration tank:
Number of aeration tanks:
Volume capacity:
Aeration time:
Air flow rate:
1,860,000m3/day
I50mg/e
8.4 m wide, 100 m long, 10 m deep 4 turns/tank
12
3 1,000m3/tank
4 hours
7.5 times of influent flow rate
244
-------
2.5.2 DISTRIBUTION OF SUSPENDED SOLIDS AND STREAM VELOCITIES
IN THE AERATION TANK
Stream velocities actually measured in aeration tanks where the diffused air
flow rates were 5 and 7.5 times as much as the amount of influent are shown in
Fig. 2.13.
Fig. 13 Velocity of ML in Full Scale Tank
V
17
"^
\.
4.3
8
• *
8 (11.9)
14.5
(9.7) |
41.5 (27. 7J
4.3
6
""!
CO
p
-------
2.5.4 CONSTRUCTION COSTS
The construction cost for unit volume of the 10m deep aeration tank is
approximately 1.4 times higher than a 5 m deep tank.
2.6 COMPARISON OF DIFFUSER AND JET AERATOR IN DEEP
AERATION TANK
In recent years, the jet aerator developed in the states has also been available
in Japan. It is well known that although the running cost is high, it features a
greater oxygen transfer efficiency. This means that it can transfer greater amounts
of oxygen without increasing the air flow rate.
In recent years, the jet aerator developed in the States has also been available
suddenly increased because of several reasons after the blower room and main air
pipes had been completed. There was no available space left to extend facilities to
cope with the increased quantities, so the only alternatives were to deepen the
aeration tanks, and improve the oxygen transfer efficiency without increasing air
supply equipment. The jet aerator seemed to answer the needs very well.
The aeration tanks at this plant measure 10m deep, 10m wide, and 76 m long.
The jet aerator was installed at 5 m below the surface. Performance of the system
were as follows.
Influent BOD: llOmg/B
Effluent BOD: lOmg/C
Detention time (for Q): 7 hrs.
F/M: 0.3 kg BOD/kgSS/day
Air flow rate: 0.37 kg BOD/m3
Power consumption: 2.9 times as much as influent rate
kHW/kg BOD kHW/m3 /inflow
Pump
Blower
Total
246
-------
Fig. 3.14 Full Scale Deep Aeration Tank in Hiagari
-------
Fig. 3.15 Full Scale Deep Aeration Tank
00
\MLPipe (For Future)
Ail Pipe 600-2000
-------
CHAPTER 3. EXPERIMENTAL STUDIES ON PERFORMANCE OF RAPID
SAND FILTRATION PROCESS FOR TERTIARY PURPOSE
3.1 Filtration Study at the Tokyo Full Scale Plants 250
3.1.1 Coagulation-Sedimentation Filtration Experiment 250
3.1.2 The Comparative Experiment of the Upflow Filter and the
Downflow Filter 258
3.1.3 Summary 296
3.2 Filtration Study at the Kyoto Pilot Plant 298
3.2.1 Solid Removal by Filter Under Varying Flow 299
3.2.2 Solid and Organic Removal by Carbon Contractor 313
3.2.3 Summary 321
249
-------
3. EXPERIMENTAL STUDIES ON PERFORMANCE OF RAPID SAND
FILTRATION PROCESS FOR TERTIARY PURPOSE
3.1 FILTRATION STUDY AT THE TOKYO FULL SCALE PLANTS
3.1.1 COAGULATION-SEDIMENTATION FILTRATION EXPERIMENT
a. Generality of the Tertiary Treatment Plant
The department of Sewage Works of Tokyo Metropolitan Government and the
Ministry of Construction have jointly constructed the pilot plant of practical scale
for tertiary treatment in Minamitama Sewage Treatment Plant of Tokyo. The
construction started in August of 1974 and was accomplished in March of 1976.
This plant comprises a sedimentation tank and two filter basins for the purpose of
removing suspended solids, BOD and phosphorus from the secondary effluent of
sewage treated by the activated sludge method.
Fig. 3.1.1 Flow Diagram
Signs
Re
F
L
X
A
C
1
0
®
a
IS
m
R
HeadLoss
Flow
Level
OpenDegra
Alarm
Control
Indicator
Calculation
Signal
Transmitter
Magnetic
FlowMeter
Calculator
Resistant
Current
Converter
Electro
-Electric
Positioner
Recorder
Automatic Meter
(Influent)
Automatic Meter
(Coagulation-Sedimentation
Water)
~~toNo.2 FilterBasin
Tr: Turbidity Meter
Tn Temperature Meter
( Effluent)
PH Meier
Electric Conductiv
-ityMeter
Al Alkalinity Meter
Do DissolvedOxygen Meier
Cl : Residual Chlorine Meter
Discharge
Channel
250
-------
Concerning the treatment capacity of the plant, the coagulation-sedimentation
capacity is 8,800 m3/day (2.32 MGD) and the filtration capacity is 17,600 m3/day
(4.65 MGD).
This plant is constructed so that the flow may be divided into two for the
experimental purpose as shown in Fig. 3.1.1; one of the flows is that of filtration to
directly filter the secondary effluent of sewage and another is that of coagulation-
sedimentation filtration to filter the secondary effluent of sewage after its coagula-
tion and sedimentation. The coagulation-sedimentation tank is the type of sludge
circulation, which is the rectangular tank with the surface area of 225 m3 (2,421 SF)
and a side of 15 m (49.2 FT) made from the reinforced concrete.
The upflow speed of the effluent of sewage is 29.3 mm/min. (1.15 inches/min.)
based on the average treatment capacity (8,800 m3/day) and the average staying
time in this tank is 22.36 h. based on the average treatment capacity. The rotation
speed of the impeller is 2.65 r.p.m., that of the scraper 3.9 r.p.h. and the width of
the impeller band 50 mm (2 inches). The surface area of each filter basin is 57.8 m2
(622 SF) its depth is 8.40 m (27.6 FT), the thickness of the filter layer is 1.20 m
(4 FT) and the excess height is 5.90 m (19 FT). This is non-constant-pressure filter
basin whose water level rises as the head loss increases.
Influent into the filter basin can be controlled constantly with the distribution
tank. The design filter speed is 152.2 m/day (2.59 GPM/SF). The structure of the
filter layer is shown in Table 3.1.1. The waste water produced by the cleaning of
the filter basin shall be stored once in the cleaning wastewater tank and then sent to
the primary sedimentation tank of the sewage treatment plant. The treatment
capacity of this plant is below that of the tertiary treatment so that it is made a rule
to perform the tertiary treatment of all the secondary effluent of sewage.
Table 3.1.1 Structure of Filter Media
Filter
Medio
Sand
Anthracite
Supporting
Grave 1
NO. of FilterBasIn
NO. 1 Filter Bosln
N0.2 Filler Basin
N03 Filter Basin
NQ2 Filter Bosln
NO.I.N0.2 Common
-,
',
Thickness
of Layer
(jnmllinch)
625(24.6)
625(24,6)
375(14.6)
375(14.8)
50(2.0)
50(20)
50(2.0)
50(20)
Effective
Size (mm)
0.61
0.7 1
1.35
1.52
2.00-3.36
336-673
6.73- 1 2. 7
127-19. 1
Uniformity
Coefficient
1.39
1 39
1 39
1 38
—
b. Generality of the Secondary Treatment Plant
This sewage treatment plant has only Tama-Newtown (the number of families
13,571 and the population 46,160 as of 1976, Nov. 1) as its drainage district and it
collects sewage through the sewer of separate system so that its maximum sewage
amount per hour is almost six times of its minimum sewage amount per hour as
shown in Fig. 3.1.2. Accordingly, the maximum sewage amount per hour is 1.58
times of the average sewage amount of a day and the minimum sewage amount per
251
-------
hour is 0.27 times of the average sewage amount of a day.
The peak time of the entering sewage amount is 10:00 a.m. and 10:00 p.m.,
and the entering sewage amount becomes extremely low at 6:00 a.m. For this
reason this sewage treatment plant is difficult to control the operation.
Fig. 3.1.2 Hourly Variation of Influent Amount
eoo
600
I4OO
3200
X
Ceoo
;soo
£430
200
August 25-26,1976
10 12 14 16 IS 20 22 24 2 4 6
Time (Hour)
The operating condition of the secondary sewage treatment facility in this
plant is indicated in Table 3.1.2. The hourly variation of the quality of the secon-
dary effluent of this plant compared to the raw sewage is as shown in Fig. 3.1.3 ~
3.1.5. The concentration of suspended solids (SS) in the raw sewage attains to the
peak both at 10:00 a.m. and 10:00 p.m. and this coincides with the peak hour of
the entering sewage amount. At the peak time of 10:00 a.m., the SS concentration
of the raw sewage was almost 425 mg/£ (3.8 times of the average SS concentration
of the raw sewage) and it was found that this concentration was quite larger than
that of almost 160mg/£ (1.4 times of the average SS concentration of the raw
sewage) at the peak hour of 10:00 p.m. The SS concentration of the secondary
effluent became the highest; almost five times of the average SS concentration of
the effluent, influenced by the peak of the entering amount. The total phosphorus
(T-P) concentration of the raw sewage attained to the peak at 10:00 a.m. and it was
almost 2.7 times of the average T-P concentration. The T-P concentration of the
secondary effluent was averaged by the secondary treatment and was constant with
almost no hourly variation.
The ammonia nitrogen concentration in the raw sewage attained to the peak
also at 10:00 a.m. (2.3 times of the average concentration) and there was almost no
variation of the effluent found. These continuous water quality tests during 24
hours were taken place 3 times in August. The load quantity, the loading average
concentration and the removal rate concerning every waste water quality were
determined based on the wastewater quantities and the concentrations obtained
during the hourly measurement, and the average value of the three tests are shown in
Table 3.1.3. The wastewater load per person in this sewage treatment district was
found to be 374 C (99 gallon) and BOD load to be 68 g (0.15 lb.), based on the
numerical value of 1976, Nov. 24 shown in Table 3.1.1. The other loads per person
are as shown in Table 3.1.4, being determined upon the Table 3.1.3.
252
-------
Table 3.1.2 Operational Conditions of the Secon-
dary Treatment Facilities of Minami-
Tama Sewage Treatment Plant
1 Xeorand Dote
Effluent Quantity {m^doy)
Returned Sludge Ratio (%)
Average Detention Time
[Primary Sedimention)(riour)
Average DetentionTime
Secondary SedimenfionXnour)
Air Blow Rolio(Air Blow
Sludge Age (day)
( I^g/m3/doy )
BOD Lood(Kg/MLSS Kg/day)
Average BOD of Sewage
Flowing into AerationTank
»3 (mg/1)
Average SS of Sewage
Flowing into Aeration Tank
*3 (mg/ 1 )
MLSS *4 (mg/1)
MLVSS *4 (mg/1 )
MLVSS/ MLSS (%)
S V * 4 (%)
S V I
1975
5 14
9510
100
*I
49
45
79
12.8
022
0.16
143
7 1
14 19
994
70
22
152
827
I030C
94
73
6.0
43
6.4
253
0.17
0.09
98
42
1795
919
51
2 1
115
11.13
9.240
104
7.8
6.7
4.5
62
18 1
0 17
0.10
1 10
60
1649
1060
65
28
167
1976
2 17
9980
94
76
62
44
69
6.6
020
0.20
1 20
92
995
857
86
80
802
5 II
13,880
79
59
45
3.4
68
58
031
0.26
137
92
1205
938
78
38
312
8.12
14670
87
5.3
4.2
3.1
8.8
64
029
0 15
120
122
1892
1.157
61
28
146
11.24
17.250
86
4.8
«2
72
2.8
80
42
0.44
0.37
1 57
100
1187
899
76
26
215
Effluent
Quo] ily
PH
Tronspe
-roncy(cm)
CODxn
(mg/1)
SS(mg/l)
BOD(mg/l
Influent
Effluent
Influent
Effluent
Influent
Effluent
iufluent
Effluent
Inlluenf
Effluent
72
71
5
85
78
1 2
1 38
6
178
5
73
70
7
1 00
68
8
1 16
3
1 61
3
73
69
3.5
100
64
8
1 30
5
185
4
73
67
5.0
1 00
72
9
1 26
2
1 60
2
7 1
70
6
1 00
62
8
1 1 8
4
180
8
7 1
69
6.5
50
49
8
1 02
8
1 1 3
6
73
4
5
64
64
1 0
128
5
183
4
* I Primary Sedimen
*2
*3 Composite sample
i Copocify-, 1950m3
5180m 3 (I83,OOOCF)
t he Aero lion fank,
Table 3.1.3 Removal Ratio by Secondary
Treatment
\Section
Woter\
OuolityX
Hems X^
S S
T-P
N H« - N
Loading
InfluentLood
Capacity
Kg/day
(LBS/doy)
2,02 1
(4,456)
70
(154)
307
( S77)
Effluent Load
Capacity
Kg/day
(LBS/doy)
150
(331)
4 1
( 90)
1 7
(37)
Average Concentration
Influent
( mg/ll
1 52
5 3
233
Effluent
(mg/1)
II
2.7
1.3
Removal
( V.)
93
4 1
9 4
Note; Meosur ing dotes ore l hree times of Aug. It -12, Aug. 18-19 and
Auo.25-26 in (976.
; Removal con be calculated out from the load copoci! y
Fig. 3.1.3
Hourly Variation of SS Concentration
in Secondary Effluent
Fig. 3.1.4 Hourly Variation of T-P Concentra-
tion in the Secondary Effluent
August 25 -26, I976
K) II 12 13 14 I5I6 17 18 « 2021222324 I 2345678 (Averoge)
Time (Hour)
Fig. 3.1.5 Hourly Variation of NH+, -N Concen-
tration in the Secondary Effluent
August 25-26,1976
Row Sewoge
Se
-X26.5)
O II 12 13 M 15 16 17 18 192021 222324 t 234567 BtAveroge)
Time (Hour)
Table 3.1.4 Pollution Load Per Capita
Woter
Quality
tems^ ^.^
S S
T-P
N Hi - N
g/doy/ person (LBS/ day/100 persons)
4 4
1 5
6 7
(097)
'(033)
(148)
253
-------
c. The Experimental Result of the Tertiary Treatment
The experiment of the tertiary treatment was conducted, using alum (Al,
(SO4)3- 18H2O) as the coagulant. The alum was added automatically in proportion
to the3 influent amount and the added amount during each experimental period is as
shown in Table 3.1.5. The experimental result of the tertiary treatment is indicated
in Table 3.1.6. When alum was added below 40 mg/C, the formation of floes was
insufficient and subsequently the formation of sludge blanket in the coagulation-
sedimentation tank becomes insufficient. Particularly when the dosage was 30 mg/8,
no blanket was observed. In the case of 30 ~ 40 mg/B of alum dosage the SS re-
moval was higher in the directly filtered effluent than in the coagulation filtered
effluent as shown in Fig. 3.1.6. As for the coagulation-sedimented wastewater, the
average removal was extremely low; below 25%. This was caused by carry-over of
the floe formed in the coagulation-sedimentation tank. The BOD removal in this
case was not greatly different with coagulation-sedimentation filtration and with
direct filtration; it was around 75% as shown in Fig. 3.1.7. The coagulation-sedi-
mented wastewater, however, as the floes caused carry-over and intermixed into the
effluent, had very low BOD removal. The T-P removal in this case was around 60%
as shown in Fig. 3.1.8 in the coagulation filtered water indicating incomplete coagu-
lation reaction and moreover around 45% in the coagulation-sedimented water due
to carry-over, both being low removal. But it was largely different from the removal
of 7% of the direct filtration and this proved the reaction effect of the coagulant.
When raising the dosage to 50 ~ 60 mg/C, the coagulation reaction was almost com-
pletely performed and the produced floes formed the blanket zone in the coagu-
lation-sedimentation tank. For this reason, the T-P removal of the coagulation-
sedimentation filtered water attained to the peak of 95%. Also concerning the
coagulation-sedimented wastewater, T-P removal was 90% at the dosage of 60 mg/C,
not so less than the coagulation-sedimentation filtered effluent. But concerning SS,
as indicated in Fig. 3.1.6, the removal of the coagulation-sedimentation filtered
effluent was only 5% above that of the direct filtered effluent. The removal of the
coagulation-sedimented effluent was also not more than 50% and it showed that
outflow of fine floes was inevitable due to the inflow fluctuation. Also as to the
BOD, the difference of the BOD removal between the coagulation-sedimentation
filtration and the direct filtration was 5%; degree of the coagulation effect being
slightly acknowledged.
Table 3.1.5 Alum Dosage
Experiment
Number
I
II
!l[
IV
E x pe rime nt Per lOd
From Sep.20foOcl 14I976
FromOcl 16 lo Nov 18.1976
From Dec.
20,1976 to Jon,IO,l977
"com Dec3ioDecl8 1976
Design Alum
Doso ge
(in the effluent )
60 mg/1
50
40
30
Averoge Alum
Dosoge
(Al/P MolRotio)
2 1
I 6
I 1
0-9
254
-------
Table 3.1.6 Experiment Results
Table 3.1.6 Continued
Item
T-P
AI/P
Ex perlment Period
Alum Dosoge
D i v i siorT^~--- __^
Total
Desd
Coagulation
-Sedimentation
-Sedimentation
Filtration
-sZin
DirectFillraton
Coo,ulor,=n
Filtroton
Ratio to Total
Ratioto Soluble
Concen
•trotion
Concen
-tration
%
Concen
-tration
Removal
Concen
-tration
Removal
Removal
Concen
•tration
Removal
Concen
-tration
Removal
Concen
•trotion
Removal
T-P
T-P
1
60ppm
N
20
Zo
20
2O
20
2O
16
16
16
16
16
16
MX
7.6
5.2
41
6P
51
53
O
57
92
3
4O
31
0
36
98
Mi
54
3£
27
35
13
66
21
O
16
78
!
99
4.0
O
35
94
Av
6£
45
33
49
23
40
0
37
66
2.6
79
0
12
96
1.995
2 46
II
SOppm
N
26
25
28
26
28
28
26
20
20
20
20
20
20
Mi
16
3
B.S
87
ze
67
8 1
63
7,
22
78
3
94
27
9
99
89
Mi
6,6
3,4
4O
4.
ie
44
20
30
0
61
39
2
46
10
0
30
71
Av
92
7.1
77
6.0
33
63
30
52
43
02
69
2
99
8
61
81
1.428
I.S57
III
40ppm
N
12
12
2
12
12
12
12
IZ
12
12
12
12
12
12
12
MX
17
5
15
6
89
16
9
28
19
9
36
13
8
41
2
27
56
3
49
II
56
75
Mi
90
6JB
67
6.6
3.4
64
O
55
9
36
35
2
87
6
O
77
56
Av
"3.
5
0
8
79
II
4
6
II
22
93
32
I
97
45
3
26
8
I
38
62
1043
1 135
IV
30ppm
N
4
12
14
14
14
,4
14
14
14
14
14
14
14
14
14
MX
a
7
14
e
93
14
3
2E
12
6
34
4
46
2
41
66
3
60
IO
86
74
Ml Av
«•'!•
8.612
7860
«'i
13 18
78 99
2027
61 89
26 54
cU
3040
78 13
0 6
7946
48 56
0.641
0.892
Fig. 3.1.6 Comparison of SS Removal
Coogulaton-Sedimentotioi
30 4O 5O
Alum Dosoge { mg / l )
Item
rurbidil)
BOD
Ex periment Period
Alum Injec tlon Rate
Division -^-~~^^
Row Water
Coagulafi
-Sedlmen
Direct Flit
Coagulati
•Sediment
Filtratio
on
on
Raw Water
Coagulat
-Sedimen
DirectFilf
Coagulot
-Sedlmen
FJltra f o
Row Water
on
1
Total
Disso-
lved
Coagulation
-Sedlmented
Direct
Filtration
Coagulation
-Sedimentation
Filtration
Concen
-Irotton
Concen
-f ration
Removal
Concen
-trallon
Removal
Concen
•t ration
Removal
Concen
-tratlon
trotion
Removal
Concen
-trotion
Removal
Concen
-trotion
Removal
-i ration
Concen
-tration
%
Concen
-tration
Removal
Concen
-(ration
Removal
Concen
trotion
Remcwl
1
60ppm
N
e
6
e
6
6
6
6
I
II
i
II
II
1
M
3
3
5
3
3
3
9
S
MX
6,2
10
97
LO
98
Bt
KX
58
09
94
0.8
96
O
14
KX
3.9
L9
47
ZB
2.
94
is
93
Mi
Z.I
02
0
01
71
0
rt
33
04
82
O2
65
0
96
3.0
0.6
IS
0
02
03
64
P.2
7B
Av
Of
3Q
49
05
91
02
93
30
O£
67
Q5
9O
0
06
93
43
13
31
09
oe
63
05
69
II
90'ppm
N
2fi
26
26
28
28
28
28
28
26
28
28
28
28
ze
10
10
10
10
10
10
10
Mi
34
4
62
85
Q8
99
03
DO
24
2
33
96
IO
98
04
OC
16
0
19
23
3.2
16
91
17
94
Mi
34
17
0
a i
83
0
95
25
OS
42
0.2
82
0
93
4.3
0.6
9
Oft
0.3
73
0.3
79
AV
89
32
32
04
94
02
98
63
II
76
CL6
90
01
96
93
,4
17
26
13
64
1.0
60
III
40ppm
N
12
12
12
12
12
12
12
12
12
IZ
12
12
12
12
4
4
4
4
4
4
4
MX
16
3
14
8
54
41
94
M
87
II
26
1
77
31
3
89
22
8
96
14
9
32
22
70
34
07
8.6
86
Ml
70
3.7
0
Qfi
69
.
59
78
2,6
39
2
67
03
76
10
6
1.3
14
36
17
44
1,6
42
Av
Z
6
9.4
23
2.0
84
23
79
24
6
ra
58
6,2
eo
42
as
12
e
24
19
55
3S
75
3£
74-
IV
30pprn
N
14
14
14
14
14
14
14
14
14
14
14
14
14
14
4
4
4
«
4
4
4
Mi
14
0
13
6
70
2.6
95
4.1
93
14
1
44
96
3.3
97
1.6
99
a*
71
48
8.2
95
B9
43
91
Mi AV
4.0 94
2.1 8.C
0 17
0412
seas
O.I 1.9
4273
4.S69
0223
3967
0.3 14
5t eo
2,°*
76 69
-X
1332
12 27
GO 73
IO 36
1,4 36
36 70
1.1 23
70 79
removal -,
f * N ; Number of Samples
MX j Maximum
Ml ; Minimum
Av ', Average
255
-------
Fig. 3.1.7 Comparison of BOD Removal
Fig. 3.1.8 Comparison of T-P Removal
f°
E
The BOD removal, however, became high in the coagulation-sedimentation and
as high as in the direct filtration. We consider from this fact that the outflow of
fine floes does not greatly influence the BOD removal.
The data of Table 3.1.1 are obtained from the daily grab samples of 10:00
every morning. In order to investigate the hourly variation of the water quality
during continuous 24 hours as for the secondary effluent, the direct filtered efflu-
ent, and the coagulation-sedimentation filtered effluent is shown in Fig. 3.1.9
through 3.1.12. The measurement period was from Oct. 13 to Oct. 14, 1976, which
were the final dates of the experiment I (the alum dosage; 60 mg/C, the average mol
ratio of Al/P; 2:1). Fig. 3.1.9 shows that rapid hourly variation of T-P in the secon-
dary sedimented effluent between 3 ~ 4 mg/C. But in the direct filtered effluent,
soluble T-P had not so wide variation between 2.7-3.3 mg/C. This was due to the
fact it was not influenced by the floes outflown from the secondary sedimented
effluent. The addition of alum this day (Al/P mol ratio) is 1.88 on the average, 2.08
in maximum and 1.68 in minimum. This is lower than the average alum mol ratio of
2.1 in the experiment I. Therefore the average T-P concentration in the coagulation-
sedimentation filtered effluent of this day was 0.28 mg/C; higher than the average
T-P concentration in the coagulation-sedimentation filtered effluent in the experi-
ment I of 0.12 mg/C. But, as the coagulation tank being the type of sludge circula-
tion, when the Al/P ratio varied hourly or in its purposes due to the variation of the
T-P concentration in the raw wastewater (secondary effluent), the T-P concentra-
tion in the coagulation-sedimentation filtered effluent was not influenced. In other
256
-------
words, when the addition of the coagulant in coagulation-sedimentation treatment
was conducted not by the Al/P ratio control but by the flow rate control, we could
obtain quite stable phosphorus removal.
Fig. 3.1.9 Hourly Variation of Total Phos-
phorus Concentration
Ocl. 13- I4,I976
A]/ P Mol Rot io
Not e '. Alum Injection quant Ity isSOpprn io water
mount.Thecompared phosphorus concentrator
ion soluble total phosphorusOoia] phosphorus
fdireci Filtration). 4 -^1.88)
10 II 1213 14 15 1617 18 19 202122 ^4 2 4 6 8 (Average J
Fig. 3.1.10 Hourly Variation of SS
Concentration
Oct. I3-I4, I976
> o- Row Worer (Secondory Effluenf)
t •*- D I reel Filtrorion
' *- Coogula tion-Sedlme tot Ion Filirofion
-•-(0.45)
^
IO 12 14 16 IS 2O 22 24 2 4
Time ( Hour)
Fig. 3.1.11 Hourly Variation of Turbidity
Fig. 3.1.12 Hourly Variation of CODMn
Concentration
Oct.l3-I4.l976
-• ••— Direct Filtration
'""" -4-(0.44>
• +<0 14 ) '
OH I2I3 I46 I6I7I8 f92O2!22 24 2 4 6 8 IO (Average J
OCT. IO- I4, I976
Row Water ( Secondory Filirofion) *<4I6)
Df reel Ftlf rorion
Coagu lation-Sedimeniot Ion FiTtrat ion
tO II 12 13 14 15 1617 18 19202122 24 2 4 6 QtAverogeJ
Time ( Hour )
Fig. 3.1.10, 3.1.11 and 3.1.12 show that concerning SS, turbidity and CODMn
the coagulation-sedimentation filtered effluent had a little more excellent water
quality than the direct filtered water.
We can get the following summary from the above described;
(1) When dosage of alum is maintained more than 50 mg/C (Al/P mol ratio; 1.6 ~
2.1), the coagulation reaction would be complete.
(2) Concerning BOD and SS removal rate; there will be no significant difference
between the direct filtration and the coagulation-sedimentation filtration: the
removals of 70 ~ 85% and 85 ~ 95% respectively were obtained. However, at the
dosage of more than 50 mg/2, the removal of the coagulation-sedimentation filtra-
tion is 5% more than that of the direct filtration.
257
-------
(3) Concerning the removal of the phosphorus; the coagulation-sedimentation
filtration can provide the removal of around 55% at the alum dosage of 30 mg/£ and
that of high as 95% at the dosage of 60 mg/C.
(4) Only by coagulation and sedimentation, the stable water quality is difficult to
be obtained. Especially at the low dosage of alum the removal of BOD and SS was
not improved due to carry-over of floes. Even at the high dosage, the SS removal
rate was not more than 50% because of the outflow of fine floes and the removal
of phosphorus was also 5 ~ 15% less than that of the coagulation-sedimentatio
filtered effluent. But at the high dosage of alum, the BOD removal nearly as high
as that of the direct filtration will be obtained.
(5) When the addition of alum was conducted by the flow ratio control, the con-
siderably stable removal of phosphorus was obtained.
3.1.2 THE COMPARATIVE EXPERIMENT OF THE UPFLOW FILTER AND
THE DOWN FLOW FILTER
a. Generality of the Facilities
With the purpose of comparing the upflow filter and downflow filter, the filter
basins were constructed in Morigasaki West Sewage Treatment Plant of Tokyo and
the experiment was performed. Its filtration capacity is 24,000 m3/day (6.3 MGD).
The constructed filter basins are two upflow filter basins and two tri-media filter
basins as downflow filter. The construction was completed in March, 1974. The
flow of the experimental facilities is so that the secondary effluent may be sent
simultaneously to the upflow filter basin and to the tri-media filter basin as shown
in Fig. 3.1.13. The surface area of both filter basins is 30m2 (323 SF) and the
structures of each filter basins are shown in Fig. 3.1.14 and Fig. 3.1.15 respec-
tively The compositions of filter media of each filter basin are indicated in Table
3.1.7 and in Table 3.1.8. The design filter rate is 200 m/day (3.41 GPM/SF) in both
filters.
Fig. 3.1.13 Flow Diagram of the Upflow and Tri-Media Filters
6 So.
7 Air
Tri-Medio Filler
I. Influent volve
2 Flllrote valve
3. Drainage valve
4 Bochvatfi water valve
5 Surface-wash water vol
Discharge
ro Tokjo Bay
258
-------
Fig. 3.1.14 Cross Section of the
Upflow Filter
Fig. 3.1.15 Cross Section of
Tri-Media Filter
Table 3.1.7 Filter Media Characterization
of the Upflow Filter
Filter
Medium
Support
media
Total
Depth
Nome
Sand
Gravel
Gravel
Gravel
Specific
Gravity
2 63
265
2 65
2 65
Depth
( m )
I, 700
250
250
I 50
2, 350
Particle Size
0-8 ~ 2 0
20 ~ 3 0
8 0 ~ 12 0
40 0 ~50 0
Effective
, size
(m m I
I 2
—
Uniformity
Coefficient
I. 27
—
—
Table 3.1.8 Filter Media Characterization
of the Tri-Media Filter
Filler
Media
Total
Depth
Support
Media
Total
Oepl h
Name
Anthracite
Silica
Sand
Garnet
Specific
Gravity
I 39
2 62
4 05
Garnet
Grave I
Gravel
405
2 65
2 65
265
Depth
420
230
I I 0
760
75
60
60
60
I .0! 5
Rjrricle Size
0 84 ~ 2 0
0 42 ~ 084
0 18 - 0 42
iffecijve
I mWf
I 22
0 42
0 29
Uniformity
Coefficient
I 4 I
I 46
I 53
I 5 ~ 3 5
5 0 - 10 0
I 0 0 ~ 20 0
20 0 ~ 30 0
2 0
—
—
—
I 80
—
—
—
b. Experimental Results
(1) Water quality test results
From the middle of August through September of 1974 (summer season), the
both filters were operated at various filter rates; 100 m/day (1.7 GPM/SF), 200 m/
day (3.4 GPM/SF), 300 m/day (5.1 GPM/SF), 400 m/day (6.8 GPM/SF) and 500
m/day (8.5 GPM/SF) and a test at one filter rate was continued for 3 weeks. From
November 14 to December 26 of 1974 (winter season), the filters were operated at
the constant filter rate of 300 m/day (5.1 GPM/SF). Sampling time was 10:00 a.m.
every morning. The average values obtained from the chemical analysis of samples
of this test are listed in Table 3.1.9. Numbers of samples were 4 ~ 6 for each of
a given filter rate in summer season and about 14 in winter season. In addition to
the measurement of the above quality characteristics, hourly variations of BOD,
COD and SS were observed as shown in Fig. 3.1.16 through 3.1.20. From these
analyses, the following results were obtained:
259
-------
Fig. 3.1.16 Water Qualities with Time
(Filter Rate 100 m/d)
Fig. 3.1.17-1 Water Qualities with Time
(Filter Rate 200 m/d)
-Tri-M
-Tri-M
SS
CO Dun
BOO
a SS
0 CODun
a BOD
--O--O-- Influent SS
--•"•-- InfluentCODui
—o-tr- Tri-MedioSS
• • Tri-MedioCODMn!
A
/ \
T ime I fir;
Fig. 3.1.17-2 Water Qualities with Time
(Filter Rate 200 m/d)
--0--0-- Influent SS
--•-*-- •• CODMi
--O--0-- BOD
^
21 23 I 3 5 7 9
Upflow SS
Upftan CODMn
260
-------
Fig. 3.1.18 Water Qualities with Time
(Filter Rate 300 m/d)
Fig. 3.1.19 Water Qualities with Time
(Filter Rate 400 m/d)
Filter Rote 300 m/doy
I' IS il 23 I 3 5 7 9 M
Filter Rote (400m/ doy)
--o-o- Influent SS
'-•--*-- Influent CODMn
—o-o— Tri-Med.o SS
• » Tn-MedioCODun
A
Upflow SS
Upf lowCODMn
22 1
Time ( hr )
Fig. 3.1.20 Water Qualities with Time (500 m/d)
_H><^. Inf SS I
--•--•-- Inf CODMn I
--©-«-- Inf BOD |
—o-o— Tri-Medio SS |
* * " CODMrt
-©-0- ., BOD
Filter Rale 500 m/rjoy
-o—o— Upf'ow S3
• « UpflowCODur
-0-0- Jpllow BOD
261
-------
Table 3.1.9 Water Quality Characteristics
^Filter
v5<
ss
COD
Cr
COD
Mn
BOD
T-N
K-N
NH3
-N
N02
-N
N03
-N
DO
UBS
PH
T-P
Infbent
Effluent
Removal
InfLent
Effluent
Removal
Influent
Effluent
Removal
Influent
Effluent
Removal
Influent
Effluent
Removal
Influent
Effluent
Removal
Influent
Effluent
Removal
Influent
Effluent
Increase
Influent
Affluent
Increase
Influent
Effluent
Decrease
Influent
Effluent
Removal
Influent
[ffluenl
nfluent
Effluent
Removal
m/d
I 00
Upfbw
9
0 7
92
Tri
-Media
I
0 7
92
21 I
IS 7
26
5
4.7
I 6
8
3 2
63
8
7 6
7 3
16 2
2 3
6
5 0
I I
6
3 3
62
2
7 8
4 9
5 6
4 7
I 6
5 0
I I
3 6
3 I
I 4
3 5
3
0. 09
0 48
530
2.9
272
- 7
S
2 6
49
0.52
580
26 I
- 10
I
0.9
83
0 I 6
0 17
-6.3
O.I 7
- 63
7 2
7 2
7 I
m/d
200
Upflow
6
0.6
9 I
Tri
-Media
9
0.4
94
2I.9
16 0
27
5
4.5
I 0
I 5. 9
27
0
4.3
I 4
7 I
2 3
68
4 4
38
7. 9
7 6
3 8
7. 8
I 3
5. 3
4 2
21
4 6
I 3
3 6
2.8
22
3 3
8
0 07
0.63
900
2.
2.82
8. 5
5
I. 3
75
0 36
51 0
0
2.8 I
8. 1
2
04
92
0 23
0.26
- I 3
0.27
- 7
7
7 I
7 I
m/d
300
Upflow
Tri
- Media
91 (97)
07 (09)
92 (9 I)
0.9(1 2)
90(88)
2I.I ( 31 7 )
16.5(19.5)
221 39)
16 5( 20 9
22 (34)
5. 6 (67)
51 ( 54)
9(19)
45 ( 5 7)
20 (15)
8.6 15.6)
2.5 (39)
71 (75)
1.9 ( 5.5)
781 65)
82 142)
7. 6(136)
73 (42)
8 1(13.3)
1 2(6 3)
5. 6 (13 2)
4-^ (12 1)
14(8)
5. 5( II 8)
5(11)
36 (96)
32(9 1 )
11(5)
3 8(8.5)
-6 I 12)
0 09 ( 0. 05 )
0. 54(0 I2)|o 14(0 31)
660(240)|I60(620)
291 (0.97)
2.63(1 45)
-96 (60)
5. 1
2.3 (6 0)
55 (1 6)
6.89(1.14)
-0.7(28)
(6. 1 )
36(25)
29(59)
0 16 (0.56)
016(0.19)1017(0.38)
0 (66) [- 6(32)
7 2
7 1
7 2
(473)
( 3. 9 5 )
(165)
(4 26 )
(99)
m/d
400
UP«°» I^MBiia
6.9
0 9
8 7
0.9
87
21 9
17 1
22
16.9
23
5 0
4 7
6
4. 4
1 2
7. 1
2. 8
6 1
2.8
6 1
7. 9
7 5
5. 1
7 5
5 1
5 3
4 2
2 1
4 2
2 1
3.6
2.5
3 1
3 0
1 8
0 07
0 62
890
2
2 73
50
5
0.8
85
Q53
760
60
2 79
6. 6
2
0 6
89
0 23
0.21
22
0.23
0
7 1
7 1
7 1
m/d
500
Upflow
-TWedia
7 3
0 9
88
08
87
23 5
1 73
26
16 9
28
5 7
4.2
26
4 1
28
1 6.9
3.6
79
4 4
74
8 6
8.8
7 4
8.8
7.4
7 0
6 0
1 4
6. 1
13
4 5
4.3
4.4
4 1
8. 9
0.09
0 28
200
2
2.45
2 5
5
1 3
74
0 08
-10
39
2.66
11.3
.0
2 0
60
0 37
0 37
0
7
72
0. 37
0
2
7 3
data except the removal
pressed by %
is mg/1
1) Regarding the effluent quality characteristics, there was no significant differ-
ence found between the effluents from the upflow filter and the tri-media filter.
2) No difference of the effluent qualities from the both filters was caused by the
variation of the filter rate.
3) The both filters could produce the stable effluent qualities against the influent
quality fluctuation.
4) SS concentration in the effluents from the both filters averaged less than 1.0
mg/£ during the summer season and less than 1.2mg/C during the winter season
(average SS removal: 90% on the both systems).
5) The effluent BOD concentrations from the both filters averaged less than 4.4
rng/C in the summer and less than 5.5 mg/C in the winter (average BOD removal
ratio: 60 ~ 80%).
6) Despite of the significant BOD reduction, CODcr and CODMn removals were as
low as 20 ~ 25% and 10 ~ 20% respectively.
7) Nitrogen removals were 1 ~ 7% in Total-nitrogen, 10 ~ 20% in both Kjeldahl-
nitrogen and Ammonia-nitrogen.
8) Nitrification took place in the filters in some degrees.
9) ABS removal could not be expected through the filter systems.
262
-------
10) pH change was not observed through the sand filter system.
(2) Cleaning of filter basins
When filtrations are continuously conducted, suspended solids in the raw water
are filtered and stored in the filter bed. As the amount of suspended solids stored in
the filter bed increases, a filter head loss rises and finally reaches a terminal head loss
because the pore spaces of the filter media are clogged with the suspended solids.
In such filter condition, it is difficult to obtain the designed filtration rate. Then,
it is required to perform an operation of washing the filter bed and cleaning the
suspended solids stored in it. This operation is so called backwash.
The backwash program for both filters can be carried out manually or auto-
matically. The automatic filter backwash is controlled either by time period of
filtration, filter head loss and effluent turbidity. And also any patterns of backwash
procedure can be selected with a pinboard timer that has 6 variations and 30 steps.
A desirable backwash may be such that initial head loss does not increase. The em-
ployed backwash procedures are as follows.
1) Backwash procedure for the uppflow filter
An example of a backwash program is shown in Fig. 3.1.21. Here will be
described the explanation of each stages.
Fig. 3.1.21 Time Schedule of the Upflow Filter Backwash
Time
Backwash Operat ion
<
o
~<
O
-o
o
u
1*
15'
t
f
£
I
20'
DO"
Wotei
3'
j
l'45'
I1 45
''TO'
^^-~"
18
dis
po"
t
(1
c
c
06'
horg
3'
2l'
e
30"
t
Ive
25
•3
30' 2
Air
200"
[ t
r r
C
" C
(•
i
I
c
,20"
I
/
0"
3' 30"
Wa
baCfc
4'
30"
Bat
2f
er b
ash
30"
r
(
-t
Inf
Fill
kwo:
'00"
ickw
5'
uent
ratio
h W
N25"
30"
3;
sh
30"
CI
C
c
J
c
T
Vol
n Vo
20'
iste M
'30,
36
Water
2' 45'
c
<
e
Ive
I'3C
arer
39
5"
disci
3'3C
j
c
<
c
Valv
25'
30
45"
4I'4
arge
Air
'2'0t
C
C
t
i
?o"
I '3
»
/
5"
Wa
DOCkl
" 4'
3"
S
,
46'
rer b
rash
30"
I
c
c
i
a
c
•c
5"
rjckwi
7'
K25'
J3°"
— K Bi
52
sh .
30"
C
C
c
o :
™ I
Air
CkWQ!
45"
55'
Sta
2'00'
c
c
i
T.
i
l'30
releo
h Air
45"
d sti
5'
.
l'45'
se V
Valv
15
00'
II
DO"
r
I
(
C
T
I'4E
alve
45"
T
5
2'30"
263
-------
i) Backwash start: Filtration run is terminated on receiving the backwash start
signal and the pinboard timer start.
ii) Water drainage: When the backwash stage starts, the filter influent and effluent
valves close and the drainage valve and the backwash waste water valve open so that
the water level in the basin lowers.
iii) Air blow start: After water level is read to be zero by the level meter (air purge
system) positioned at 10 cm below the filter surface, another timer works and in
4 min. the air blower starts. During the air blow, the pinboard timer stops. Water in
the bed is completely withdrawn within 4 min.
iv) Water backwash start: in 2 min. after the air blow starts, a backwash water
pump starts. Because it takes some time until the air blower achieves the deter-
mined flow. Backwash flow is as low as 10 m3/m2/hr. jn fjrst 5 mjn^ after ^en jt
increases up to 40 m3/rn2/hr. The time when the backwash flow changes from 10 to
40 m3/m2/hr. is synchronized with the end of the air blow. The backwash in the
low flow has the purpose of extending the time of air-water phase as long as possible
and of discharging suspended solids as much as possible.
v) Air blower stop: When backwash water level rises up to the point of 20 cm
below the top of the trough, the air blow stops. This is so as to prevent the sand
media flowing out. The working time of the blower is generally 7 min.
vi) Water backwash stop: The backwash pump stops having worked for 10 min.
after its start.
vii) Water drainage: The drainage valve opens simultaneously when the backwash
pump stops. Then, all water in the bed is discharged with the same operation as the
step of ii).
viii) Air blow start.
ix) Water backwash start: Water is sent in the same procedure as iv), from the low
flow to the general flow.
x) Air blow stop: The same operation as iv), the operation time is almost 7 min.
xi) Water backwash stop: The operation time for the second water backwash is
2 min. longer than that for the first water backwash. It is continued for 12 min.
The longer time is taken with the purpose of completely discharging suspended
solids and air remained in the filter bed.
xii) Standstill time: The backwash operation is kept still for 2 min. after the back-
wash pump has stopped in order to settle the filter media.
xiii) Filtrate discharge: An influent valve opens and a next filtration service starts.
But the backwash wastewater valve is kept open during 5 min. and the first portion
of the filtered water is discharged from the trough.
xiv) Termination of backwash process: The effluent valve opens and the backwash
waste water valve closes. Then, the next filter service starts.
2) Consideration of the backwash system for the upflow filter
i) The main consideration of the backwash procedure for the upflow filter should
be given to the final stage of the backwash; stand still time. In this stage, the back-
wash operation is paused after the backwash pump stops and the water level in the
filter is maintained as it is in order to settle down the sands expanded during the
backwash process. In view of dense packing of filter media, this stage has an impor-
264
-------
tant relation with a breakthrough of suspended solid from the bed which is discussed
in the section (8). Then, the perfect compaction is intended by opening the drain-
age valve and discharging the remained water. Moreover, to keep the drainage valve
open is effective to absorb the excessive high pressure caused temporarily when the
influent valve opens at the rebeginning of filtration and to prevent the rapid change
of the pressure imposed to the sand media for the purpose of its stabilization. A
time requirement to decrease the raw water contained in the headchamber (maxi-
mum waterhead; 3.0 m) to the constant water level is the reason why the high pres-
sure is produced.
Since August 6, 1975, the following operation was added to the final stage of
the operations shown in Fig. 3.1.21. In 2 min. after the pause, the drainage valve is
opened. When the water in the filter basin is discharged to just below the sand
surface, the influent valve is opened and the raw water of the amount for filtration
is sent in. After 5 min. of discharging the filtered water out of the backwash waste-
water valve, the effluent valve opens and the filtration starts again.
ii) Increase of backwash water amount: General flow is increased to 1,400 m3/h
(0.78 m3/min.m2) for treatment of the raw water with high turbidity.
3) Backwash procedure for the tri-media filter
Fig. 3.1.22 shows an example of backwash for tri-media filter. Here will be
described the explanation of each stages.
Fig. 3.1.22 Time Schedule of the Tri-Media
Filter Backwash
Time
g1
*
0
<
s
•o
5
13-
30" Od'
32
2' ;
S
|
5
I'lO
2' 30
0"
!
3*
Bo
-^=^-i
0" 3,
TOrgt
rod
!
i
Inf
1" Su
l'2
:kwa
__
i'30'
Wate
Surfc
Bockwash W
c
3
fuent
face
>" a
h Wa
Fifti
! !
1
> 1
i
Bo
:e W
7 00
Val
wash
ckwc
er Wo
ate
4o';
;kwo
shina
I
Valve
shW(
ste V
d'43
h
300
^
o
34
icr V
alve
, _Va 1 ve
i
30'4
Stan
SI ill
l'3C
n
J
3
l'4C
Ive !2
2'3C
od'
We
3
3"
48
ter
roqe
DO'
j'i
od'
-n
3
0
0"
y
Fig. 3.1.23 Time Schedule of the Tri-Media
Filter Backwash
(for High Turbidity)
(Tm^e)
Bockwosh
Operation
Valves
Opera t ion
? 10 20 c , 3,°
,.,„.., SurfoceWoshOmm) AirWoshdmm }
u, SurfaceWater
.| StortLevel
•5' Backwash Start
— "x,0"
2jO^
WaierBockwosh(4mm) Water Rock wo
Water OrQinoqe(3min)SurlocgWosr)
HypochlonteAdd.it
0°^? ^ ^^™?a^
ill tl[li
' 1 1 1 " ! | I
Influent Valve! Close )
Bockwash Waste Water Valve (Open)
WoierSiorogeOrnin,}
shfflmm)
j iause(imtn)
on(4mm) |7ppm
-
3^ \34Surfoce WashVolve* V~\34
,25^ ^'25" Backwash \'tti
V!25"
2<^ \20" water Drainage Valve
""V!^
30/\30' Air Vo
Filtrate Valve _(_Close )
ve(Close)
I40>
i) Backwash start: On receiving the backwash start signal, the pinboard timer
starts.
ii) Water drainage: The effluent and influent valves close and the backwash waste
water valve opens. Thereby, water in the basin is discharged.
iii) Surface wash start: The water level lowered to the top end of the trough, the
level meter detects the water level and the signal is sent to start the surface wash
pump. During this time the pinboard timer stops.
265
-------
iv) Water backwash start: 1 min. after the surface wash pump starts, the water
backwash pump starts.
v) End of surface wash: The surface wash pump stops after the 8 minutes' opera-
tion. The surface washing and water back-washing works are simultaneously con-
ducted for 7 min. This simultaneous operation is essential to prevent suspended
solids removed on the bed surface from producing mudball. Deficiency of surface
washing may cause mudball forming because the suspended solids remained on the
dead area of the bed surface agglomerate anthracite particles.
vi) Water backwash end: The water backwash pump stops working in 10 min. after
its start; it continues working for 3 min. more after the surface wash pump stopped.
This is for the purpose of discharging completely all the solids in the filter bed.
vii) Operation pause: The filter is kept still for a minute after the end of water
backwash in order to give enough time for the filter bed settling down.
viii) Water storage: The influent valve opens and the backwash wastewater valve
closes. Then water is stored until water level rises up to the level for a normal filter
service.
ix) Termination of backwash: The filter backwash is terminated by opening the
effluent valve.
4) Consideration of the backwash system for the tri-media filter
A major problem in the backwash system for the tri-media filter exist in the
slime production in the filter material, especially in the sand media. This tack slime
production may cause the low fluidity of the filter media in the backwash step so
that an effective cleaning of the bed can not be achieved. In order to solve this
problem, the backwash procedure was changed as follows.
i) Sodium hypochlorite is added during the water backwash.
When cleaning is repeated without an addition of hypochlorite, the slime is
produced in the sand layer and the fluidity of the sand is lowered. On this account,
the initial head loss gradually increases. The initial head loss increased about 10 cm
(Filtration speed: 200 m/day) for 2 months from June 4 to August 8, 1975 as
shown in Fig. 3.1.25. This period is the season when the temperature becomes
gradually higher. Therefore, when the viscosity of water is lowered and the initial
head loss generally tends to decrease, we may conclude that this increase of the
initial head loss was not influenced by the temperature. The addition of sodium
hypochlorite started from August 8, 1975. Its addition starts 2 min. after the full
opening of the backwash valves and stops in 4 min. All the above operations are
automatically conducted. The adding point is just before the backwash pipe enters
the filter basin. The added amount is 250 C/h (1.1 GPM). A percentage of effective
chlorine in the sodium hypochlorite solution is 10% so that the chlorine injected
concentration is 17 mg/£. As the effective capacity of the storage tank of sodium
hypochlorite (made from F.R.P added polyethylene, with the cylindrical cap) is
2,0002 (528 G), the supplement of the sodium hypochlorite is required once 2
months for the operation of two filter basins (a basin; 30 m3). After the cleaning
with an addition of sodium hypochlorite continued for a month since August 8,
1975, the initial head loss was lowered by 30 cm. This has proved the effectiveness
of the above described cleaning method.
266
-------
ii) Air-water phase cleaning
Mixing cleaning of air and water is additionally performed after water is drain-
ed out of the basin.
On August 16, 1975, the filtration of the raw water with high turbidity has
begun (in mixing with the drained secondary sedimented sludge). After about a
month, the condition of the filter layer of one of the two basins has become worse.
SS accumulated on the anthracite surface layer was not cleaned off, but fell down
along the wall surface, and reached the supporting gravel layer. It was found that
the cleaning system shown in Fig. 3.1.22 has been insufficient for this kind of raw
water with high turbidity. Then, air-water mixing cleaning was conducted and also
the quantity of backwash water was increased up to 1,500 m3/h (0.83 m3/min.m2)
(20 GPM/SF). The quantity of air used for this purpose was to be 15 Nm3/min. (0.5
Nm3/min.m2) (1.64 GPM/SF). In this way the raw water with middle strength of
turbidity was filtered from October 21 to November 3, 1975, but the above written
deterioration of the filter performance was not observed. The altered backwash
system is described in Fig. 3.1.23.
i) Backwash start and drainage: On receiving the backwash start signal, the
filtration process is ended and the backwash process starts. In the first step of the
pinboard timer, the influent and effluent valves close and the backwash wastewater
valve opens. This state is kept until the water level is lowered to the design level that
the surface washing can be performed.
ii) Surface wash and water backwash: The first cleaning is with the purpose of
flowing out SS accumulated on the surface of the filter bed and consists of 3
minutes' surface washing and four minutes' water backwashing (overlap of 1 min.).
iii) Drainage: The drainage valve being opened, water level of the filter basin is
lowered charged to the bottom out of the filter basin, in order to perform the
following air-water mixing backwash effectively.
iv) Air-water mixing backwash: The air blower starts first, the backwash pump
starts next, and the air-water mixing backwash is performed with pushing up the
backwash water to bed surface. The air blower is driven only for a minute. Then
the water surface is just above the anthracite so that there is no fear that the filter
media are carried over the trough. The purpose of this air-water mixing backwash is
to clean out SS within the filter bed.
v) Surface layer wash: This is conducted by turning the surface washing equip-
ment during the operation of the water backwash pump. The surface washing equip-
ment is to be turned within the expanded layer of anthracite so that the water back-
wash, and the cleaning of the inner portion of the anthracite layer is performed
effectively.
vi) Chlorine addition: The addition of sodium hypochlorite starts 2 min. after the
second backwash pump start and it continues for 4 min. The hypochlorite addition
is not sufficiently effective in the first backwash because the large part of hypo-
chlorite is consumed by SS remained in the filter bed.
vii) Pause and water storage: After settling down the filter media, the influent valve
opens and the backwash wastewater valve closes. Then water is stored and after the
water level is raised to the level for a regular filtration, the effluent valve opens and
267
-------
the filtration starts again.
5) Quantity of backwash water
The design flow and the actually used flow for the backwash of each filters are
presented in Table 3.1.10.
Table 3.1.10 Quantity of Backwash Water
the Updow
Filler
theTr.-Meckl
Flier
Backwash Water
(Raw Waterl
Backwash air
Surface wash Water
(Filtrate)
Backwash Water
(Filtrate)
Design Flow
per basin
300 m?H
I 200 .1
N - mVu
45 H
45"^"
m^H
(,100 H
per basin
IOmVH
40 ,,
.N-mfc
l.5m^H
367"^
Total
Amount
347 m3
N-rrtf
440
3
6 1
m3
172
(3) Initial head loss variation
A head loss produced at the rebeginning of filtration run after the termination
of the filter backwash is so called the initial head loss. The continuous investigation
of the initial head loss testifies a degree of the filter bed cleaning. If an ideal back-
wash could be achieved, an increase of the initial head loss may not be observed.
Adversely an increase of the initial head loss may indicate an incomplete cleaning of
the filter bed. The initial head loss variation of the upflow and the tri-media sand
filters from August 15, 1974 to March 15, 1976 was investigated.
1) Initial head loss of the upflow filter (Fig. 3.1.24)
A stable condition of the initial head loss was observed until August 15, 1974.
It might be associated with a chlorine addition of 3 mg/C to the influent. After
then, the chlorination of the influent was stopped to obtain a stable effluent quality
and a filter rate was increased to 400 m/day (6.8 GPM/SF), 500 m/day (8.5 GPM/
SF), and 550 m/day (9.4 GPM/SF).
A rapid increase of the initial head loss was experienced in this test period. So,
chlorine solution was temporarily added to the influent on November 6. The initial
head loss was maintained to be low for several days since chlorine was added. But
after that the initial head loss began increasing again rapidly. In the previous wash
system, the air blow had been carried out in the condition that water was filled in
the filter bed. In the modified wash way, however, water is discharged initially
down to the bottom of the bed and the backwash is conducted from the low water
flow to the regular water flow as described in the section of (2) - 1). In this way, the
initial head loss was maintained to be low without the chlorine addition as shown in
Fig. 3.1.24.
From January 7, 1975, the period of the backwash time was shorten to a half
of the usual one, but the low initial head loss was not maintained. Also, it was
found that a constant initial head loss could stably obtained by providing the back-
wash once a day. Moreover, the filter was operated at the standard filter rate (200
m/day) for 4 months from the beginning of June to the middle of October of 1975.
In this period the initial head loss was constantly maintained at 30 cm. This proves
that the above suggested backwash method can be applied for the practical opera-
tion.
268
-------
1.5
1,0
° Q5
Fig. 3.1.24 Initial Head Loss Variation of the Upflow Filter
No. I Uptlow Filler
No.2 Uptlow Fi Her
550 m/doy
5OOrn/doy
500m
}3OOm/doy
Improvement of Backwash Proced arefBac kwa «h «tart» after emptying the ba i in)
400m/doy
$
300 m/day
200m/day
Filter Rat* 100 m/d ay
C h 1 p. r i n o Addition
No.I 3OOm/day
Shorten the Backwash Period
Chlorine Addition Chlorine Addition
Chlorine Addition
9Om/day
TO m/doy
8/15 20233O9>» 9 14 19 24 2910/49 14 19 2'l 29 l»/1 6l'l 16 2\ 2612/1 6 II 16 21 2631 1/5 O 15 2025 3O2/4 9 14 19 2454 6 It 16 21 2631 4/9 10 15 2O 2530 5/9 IO
Mont h / Da te
E 1.0
No. I Upf low Filter
N o. Z Upt 1 ow Filter
LV 423 m /da y
.V
LV 365-32D m/doy
LV 200 m/day
Small Flow Flucfafion
LVI90m/doy LV |9om/doy E*P«'
LV70
in/day
LV IOO
m/doy
LV20Om/day Large Flow Fluctuation Experinenl
5/9 10 1520 25 306/49 14 1924297/49 14 19 24 298/38 13 20 25 309/49 14 19 242910/49 H 19242911/38 13 18232812/3 IO 1520253012/4914 192429
Month/Date
-------
Fig. 3.1.2& Initial Head Loss Variation of the Tri-Media Filter
1.5
E
V>
o I.O-
_i
•o
O
«
I
o 0.5
5OO m/day
No.I Tri- Media Filter
No.2Tr i - Wedi o Filter
No,2 4OO m/day
IOO m/day
(ihiorine Addition
20O nn /day
77jn/doy IOO m/day
Chiorine Addi tion cyorion Addi t ion Chjorion Addition Chior ion Addi ti o n
8/15 20 25 30a4 5 14 19 242910/45 14 19 2429 ll/l 6 II 162126124611 16 21 2631 1/5 IO 12 20253O2/4 9 14 19 243/16 I I 16 2| 26314/5 IO 15 2025 305/510
Day
o I.O
OQ3-
LV2OOm/da
No. I Tri - Media Filter
No.2 Tri-M «d ia Filter
BocKwasn by Addition of Sodium Hypochlorite
Secondary Sedimentation
TanK Drained Sludge
V2OOm/doy LV2OOm/day
Backwoshing Addition of Sadiun
Hypochlori t«
Incomplete Backwash ( Si multoneouj Bockwa sh of Two Filters)
Secodorv Sedlimenfation TanK Drained Sludge Addition
Addition Backwash Layer (Stop Filtration) Incomplete BackwashfSim
- -
LV 212 m/day""' taneouj Backwash Two
. ri itGrs )
LVII7m/doy
Backwajhing by Addition of Filratiofl
5/5 IO 15 2O25306>»9 14 1924297/49 14 19 24 29 B/3 9 13 2O253O9A9 14 19 24 29IO/4& W 19242911/38 13 18 23 2'8I2> 6 l'l 16 21 26 3'l 1/4 5 IO 152025302/49141^243^5101*
Day
-------
2) Initial head loss for the tri-media filter (Fig. 3.1.25)
In the operation of the tri-media filter, no addition of chlorine showed an in-
crease of the initial head loss as well as in the upflow filter operation. A change of
the backwash system, in this case, was not effective to prevent the initial head loss
increase. When the operation was performed with the backwash of once a day at the
standard filter rate (200 m/day) (3.4 GPM/SF), the initial head loss increased about
10 cm by August 8 (in about two months). Then, in the backwash system, sodium
hypochlorite was injected for 5 min. in 4 min. after the backwash start. The injec-
tion rate of effective chlorine was 10 ppm. The initial head loss was lowered about
30 cm on August 9 in a month after this backwash start and since then the initial
head loss could be maintained at about 20 cm. Thus, the backwash system with the
addition of sodium hypochlorite made the stable practical operation possible for tri-
media filter.
(4) Filtration period and initial head loss
Concerning the hourly variation of the filter head loss and the effluent tur-
bidity, the data obtained at a filter rate of 300 m3/day (3.4 GPM/SF) are shown in
Fig. 3.1.26, which indicates that the effluent turbidities from the both filters were
not influenced with the fluctuation of influent turbidity. However, there was a
great difference between the upflow and the tri-media filter with respect to the
time period of filtration run that could be applied. Fig. 3.1.27 shows the relation-
ship between a terminal head loss and the filtration period at various flow rates.
The terminal head loss means the head loss reached at the end of the filtration run.
Fig. 3.1.26 Head Loss Variation and Turbidity
Characteristics in the Upflow
and the Tri-Media Filters
30i
25
_2O
E
JIG-
S'
0
oftheupflo»F»ter
the Tri-Media Fitter
Influent Turbidity
Enfluent Turbidity from the
Upflow Filer
Enfluent Tubidity from the
Tri-Medio Filer
2050
Fillrolion Period
~30(hr!
I730&302330
5.30 O30 I530 2030030 5'30 9 30
Time
271
-------
Fig. 3.1.27 Relationships of the Filtration Period and the Terminal Head Loss
on the Upflow Filter Operation
0 Hh-
FiI r e r Rate
200 m/d
300 (Clzadded)
300
400
500
30 40 50
Filtra tion Period
Fig. 3.1.28 Relationships of the Influent Turbidity and
the Filtration Period on the Tri-Media Filter
Filler Rare Average Fi H ro r ion Period
200 m/d 27. 8hr
- 3O 0 (CI2 added ) t &. I
300 150
400 ,3.5
500 5.9
m
Terminal Head Loss 2,70
10 20 30
Fi It ration Period ( hr )
272
-------
Fig. 3.1.29 Filtration Periods of the Upflow and Tri-Media Filter
Tri-Medio Updo*
\ V
- Terminal Head Loss
20 30 40 50 60
Fi Itrahon Period ( hr }
At the beginning of the experiment, there was a difficulty to employ a high
terminal head loss because of some structural problems and also a breakthrough
problem. Subsequently, an instable terminal head loss was observed. The structural
problems were of the physical damages of the FRP trough. They have been recon-
structed and now working well. The filtration periods applied to the tri-media filter
are presented in Fig. 3.1.28. Also, the average filtration periods at various filter
rates are presented in Fig. 3.1.29, which indicates that at every rates studied the
upflow filter has a longer filtration period than the tri-media filter has.
(5) Suspended solids removal capacity
The removal capacity of suspended solids in the experiment performed from
August 15 to October 30 of 1974 (in this period, a filter rate was varied in a range
from at 100 m/day (1.7 GPM/SF) to at 500 m/day (8.5 GPM/SF) was calculated by
using the following equation.
M = Q(Trxrr-Tf xrf) (1)
Where,
M
Tr
Tf
rr
rr
Q
Amount of SS removed in once filtration run (g)
Average turbidity of influent (mg/C)
Average turbidity of effluent (mg/C)
A correlation coefficient of turbidity and SS in the influent (0.50)
A correlation coefficient of turbidity and SS in the effluent
A quantity of the filtered water during one filtration run (m3)
The average turbidities (Tr, Tf) were obtained by measuring the influent and
effluent turbidity at every 30 min. during the filter runs. The correlation coef-
ficients of turbidity and SS were obtained from Fig. 3.1.30.
The amounts of SS removed by the upflow filter are presented in Fig. 3.1.31
273
-------
and that removed by the tri-media filter in Fig. 3.1.32. The figures indicate that
150 kg (1.0 Ib/SF) of SS could be removed by one upflow filter bed (30m2) and
50kg of it by one tri-media filter bed (30m2) under the following operational
conditions, filter rate; 300 m/day, influent turbidity; 20 ppm, terminal head loss of
the upflow filter; 2.40 m.
Fig. 3.1.30 Correlation between Turbidity and SS
I nfluenr
Effluent
Effluen1(Cl2 added )
Turbidity from the Turbidimeter (ppm )
Fig. 3.1.31 Terminal Head Loss and Removed Suspended
Solids by the Upflow Filter
i I o
274
-------
Fig. 3.1.32 Influent Turbidity and Removed Suspended
Solids by the Tri-Media Filter
F il Ter Role
200 m/d
300 .
400 >
10 20 30 40 50 60 70 ' 80
SS removed Uo. - s s/SO1"*)
Fig. 3.1.33 Influent and Effluent Turbidities at Filter Rate of 300 m/d
,>IOO
30
8/jB 19 20 21 22 23 24 25 26 27 28 29 30 31 %| 234 56
Day
275
-------
(6) Chlorine addition and effluent turbidity
For the control of slime generation in the sand filter, chlorine is generally
added to influent. However, the chlorine addition resulted in unstable effluent
quality. Then, chlorine addition was, principally not conducted and also other
means such as modifying the backwash system for the upflow filter and adding
sodium hypochlorite to the backwash water for the tri-media filter, were employed
for the slime control in this experiment. Fig. 3.1.33 shows the turbidities variation
in the influent and effluent from the both filters. Since the chlorine addition to the
influents were carried out for the period from August 20 to August 31 of 1974, the
effluent turbidities of the both filters showed the fluctuation. This indicates that it
is largely influenced by the influent turbidity variation.
(7) Head loss distribution in filter media
Cross-section head loss distribution through the upflow filter bed are grafically
shown in Fig. 3.1.34 and 3.1.35. Also, Fig. 3.1.36 and 3.1.37 show the head loss
distributions of the tri-media filter. Fig. 3.1.34 shows that the graval layer at the
bottom of the bed can be an effective filter medium in the upflow filter. It is also
shown by Fig. 3.1.35 that the suspended solids once caught by the supporting graval
layer gradually rise to the upper sand medium. The effective filter depth of the sand
medium above the graval layer seemed to be around 30 cm.
Fig. 3.1.36 and 3.1.37 show that in the case of the tri-media filter, about 80%
of the total SS removed was stored in the top layer of anthracite that was about 30
cm in depth. Both in the sand medium in the upflow filter and the anthracite
medium in the tri-media filter, the effective filter depth was about 30 cm. However,
in the upflow filter, the graval layer at the bottom of the bed had an effective filter
function. So that, totally, the upflow filter is able to provide a larger SS storage
capacity than the tri-media filter.
Fig. 3.1.34 Head Loss Distributions of the Upflow Filter (300 m/d)
I 2
I 3 •
276
-------
Fig. 3.1.35 Head Loss Distribution of the Upflow Filter (400 m/d)
I.O I.5
Head Loss
Fig. 3.1.36 Head Loss Distribution of the Tri-Media Filter (200 m/d)
( m- flq)
277
-------
Fig. 3.1.37 Head Loss Distribution of the Tri-Media Filter (300 m/d)
(8) Breakthrough problem on the upflow filter operation
Filter breakthrough may refer to the phenomena that the stratified filter bed is
partially broken and a water channel is temporarily made so that the stored SS at
the bottom layer is released out of the bed during a filtration run. When the filter
breakthrough occurred, a heavy turbid water can be observed above the surface of
the filter bed and the filter head loss lowers rapidly. After a while, the breakthrough
will spontaneously disappear and the head loss will increase again. However, when
the head loss increases to the point that the last breakthrough happened, another
breakthrough may occur again. Then, if the breakthrough once happened, the
filtration run must be terminated to start the backwash operation.
The initial head loss and head loss at the breakthroughs occurred since the
operation start till the present time are investigated and presented in Fig. 3.1.38, in
which the term of normal head loss means the initial head loss shown while the filter
rates were at 300 m/day (5.1 GPM/SF) and 400 m/day (6.8 GPM/SF) and the
successful backwashing of the filter bed was carried out from January 25 to Feb-
ruary 24 of 1975. Fig. 3.1.38 indicates that the following two may be considered as
the reasons why the breakthrough phenomena happen.
1) A sufficient decrease of the initial head loss may not be achieved due to the
deficiency of the filter backwash (in the case of 300 m/day).
2) Although the initial head loss is low enough, the standstill step at the end of
the backwash operation may not be provided (in the case of 300 m/day and 400
m/day).
A stress generation in the grids was measured by mounting a strain gauge on the
grid. The head loss observed at the beginning of the stress generation was ranged
from 1.70m to 1.76m (from 5.6 to 5.8 FT), as presented in Table 3.1.11.
Fig. 3.1.38 also indicates that the head loss at the time of breakthrough occur-
ring was above 1.80 m (5.9 FT).
278
-------
A mechanism of the breakthrough phenomena may be explained as follows,
based on the above investigations.
As the amount of stored SS increases and the clogging of the filter media
proceeds, the sand layer may receive the upward force which is larger than the
weight of the sand bed itself. Then, when the sand particles in the top sand layer are
uniformly arranged, the inverse bridge is formed with the grid and the force to push
the sand bed up may be transmitted from the sand medium to the grids. Thus the
sand layer can support this force. But when the backwash is insufficient and the
sand particles are coated with slime, or when the compaction of the sand layer by
the pause stage is insufficiently performed, the resistive force due to the engagement
of the sand particles can not be expected and the upward force might be released
through the portion of the sand particles. Eventually, the breakthrough of the re-
moved suspended solids may take place.
Fig. 3.1.38 Head Loss at the Time of Breakthrough
Occurrence and Initial Head Loss
Normol heod loss
I 5 20 25 (ml
Head Loss that Breakthrough Occured
300m/day
N o rmal head loss
20 2 5(m)
Head Loss that Breakthrough Occured
Table 3.1.11 Head Loss when Stress Generated
in Grid
Measure
Dote|974
Head Loss
(ml
I2-IO
I.7I
12- 13
1. 73
12 -20
1. 76
12-24
I.7I
12 -27
1.73
12-29
1.70
279
-------
(9) Consideration of the filter media used in the tri-media filter
Generally, suspended solids of influent are removed at the top layer of the tri-
media filter, as' described in the section of (7). Then in order to extend a filtration
period, an effective depth of the filter must be increased. One of factors to extend
a filtration period may exist in the particle size of anthracite in the top layer of the
filter media.
Conventionally the anthracite with an effective particle size of 1.22mm (uni-
formity coefficient 1.41) was employed. The anthracite with an effective size of
1.70mm (uniformity coefficient 1.21) was to be employed instead of the above.
Column test was carried out by using two columns filled with the anthracite of two
particle sizes (The other media are equal to the existing ones). Test results are
shown in Fig. 3.1.39. It indicates that the larger particle could increase the filtration
duration as 1.7 times longer as the smaller one.
Fig. 3.1.39 Effects of Particle Size of Anthracite
for the Tri-Media Filter
(Cml
350
50
I975.I/28-I/29
No I Filter
Anthrocile E S I22mi
Averoge 423 myd
Slope dM/dl = !75»IO
N02 Filter
Anthracite e S I 22mm
Average 427 m/d
Slope dM/dl- 0 98x10
q Influent Turbit V
.—. NO-1 Effluent Turbity
«— N02E.f f lu ent Turbity
10 20
Filtration Per lOd f hr)
Fig. 3.1.40 Head Loss Distribution After the
Change of Anthracite Particle Size
{m m)
2- °
too
'' 200
| 4- 300
5 I*™
5 O
„ 6- ,_ 6OO
_i
_ 7- ,
8-
800
900
9- IOOO
Filter Rate 2OOm/doy
Anthracite Particle Size |.70mr"
Anthracite Head Loss 2.60m
" Total Filtration Pressure 0.284 rfoy cm2
f Filter Rale200m/day
Anthracite P
-------
According to the above tests results, about 76% of the anthracite medium of
the tri-media filter (32 cm of 42 cm anthracite medium depth) was exchanged with
the larger anthracite with the effective size 1.70mm. Fig. 3.1.40 shows that the
anthracite with the effective particle size of 1.70 mm admits the deeper SS invation
and the filter media are found to be more effective.
(10) Practical filter rate
To determine the operational filter rate, the decrease of an amount of the
effluent caused by the backwash is not taken into consideration. Then, the follow-
ing equation was used for obtaining a practical filter rate, which is termed as the
filter rate that the backwash time requirement and the amount of the backwash
water are taken into consideration.
Q=24 T
v Tf
F - W
(2)
where,
Q
F
W
Tf =
Tw =
Practical filter rate (m/day)
Filter flow rate per unit surface area (m3/m2)
Backwash flow rate per unit surface area of the tri-media filter
(It is not required for the upflow filter.) (m3/m2)
Filtration period (hrs.)
Backwash period (hrs.)
The filter flow rate, F is expressed by using the operational filter rate, Q'
(m/day), as follows;
F =
1
24
Q'xTf
(3)
From the equation (2) and (3), the relationship of the practical filter rate and
the operational filter rate is expressed by the following equation.
Q' Tf - 24W m
\J rr-i i-pi ... • *• * * * ' * V /
if + lw
Calculation results by using the above equation are presented in Table 3.1.12.
It was proved that the upflow filter was superior to the tri-media filter both in the
practical filter rate and in the operational filter rate.
Table 3.1.12 Practical Filter Rate
Operalcnal
Fi Her Rare
m /day
200
300
400
500
Practical Filler Role (m / rj )
theUpflow Filler
AH : 1 80m
197 ( 15 )
293 (23)
367 [ 3 2)
478 (44)
£H" 2 70m
198 I 1.0 )
295 (171
391 (23)
482 I 3 6)
The Trj-MsdmFilter
AH : 2 70m
193 (35)
285 150)
378 155)
464 (72)
All numbers overoged 40 data of o filter
281
-------
(11) E. coli behavior in the filtration process
Usually, about 75% E. coli removal could be achieved by the both filter sys-
tems as shown in Table 3.1.13. Furthermore, it was very rare case that E. coli
number in the effluents exceeded 600. Then, when the sand filter is employed for
the treatment of the secondary effluent, the chlorination of the filter influent may
be unnecessary.
Table 3.1.13 E coli Removal Characteristics
Dole
5/2I
10 00
13 30
5/27
1 1 00
13 00
15 00
6/13
9 00
II 00
II 05
14 00
16 00
Influent
Cohlorm
11,10"
5,10*
5 , 10
II, 10"
E Coli
no
660
520
500
1300
800
2 400
2500
2 300
1 900
the Upllow F Iter
"'no™
26.10=
( 76)
9,10=
( 62)
Filter
37, I03
(75)
8*I03
(75)
E Coll
146
(72
330
! 34 )
450
(65 )
620
( 74)
500
(80)
Bodrwosh
520
(77)
480
[ 75)
2
Conform
25
148)
38, 03
(75)
9,10'
(74)
Ecoll
II 3
183)
3-fo
(56)
600
175)
510
(80)
560
175)
440
( 77)
the Tri-Medio Filter
1
=**
29,10s
74)
24, D
(59)
42X1C?
(72)
33
-------
ured with the turbidity meter of falling type of Swiss Sigrist company (UP 52-TJ).
Calibration of this turbidity meter was conducted by means of silicon dioxide (SiO2
1 mg/£ = 1 ppm). Calculation of SS removal was executed based on Fig. 3.1.41.
Fig. 3.1.41 A Relationship between Turbidity and SS when the Sludge
withdrawn from the Secondary Sedimentation Tank is Mixed.
80
70
6O
3O
20
IO
August 27 of I975
0 IO 20 30 40 55 60
Turbi di i y (mg/l)
2) Experiment result
Experiment was performed as indicated in Table 3.1.14 and the hourly varia-
tion of SS removal is shown in Fig. 3.1.42 and Fig. 3.1.43.
Table 3.1.14 SS Removal Experiment at High Turbidity Influent
Exper
-imen
Name
U- I.I
U- IZ
U- 13
U- L4
U-L5
D- f.l
D-I2
D — 13
D- \A
0-I5
D-I6
Filter
Nome
U-l
U -I
U-2
U-2
U-2
D-l
0-2
D-l
D-2
D-2
0-2
Start
Dote 1
Time
75 9/4
I 1 :3Z
759/5
I 7 34
75-9/5
4. I 6
75 9/5
IS 27
73.9/15
6:30
75.9/6
0 51
75 9/5
21-49
75-9^
IO:26
75 9/5
1 05
75 9/6
T'08
75 9/5
10 32
Average
Filter
Rate
(m/doy)
195.4
195-1
201 0
1994
1966
196 7
197 1
197 5
196 0
198 1
196 9
Filter
Run
15 13
II .56
13 .19
1 1 10
10 '38
9 .16
9 .00
8 '27
9 '08
8 :37
10 -59
Head
Loss(m)
223
242
270
270
2.67
300
2.70
270
205
270
260
Average
Turbidity
(ma/1 )
304
464
34 1
472
4| B
46.6
503
392
374
424
42.4
Effluent
Average
Turblaiiy
(ma/1)
100
191
120
1 12
0.60
3.17
158
162
109
104
175
SS
Cop'ured
(kg/tni)
3.53
4.91
385
494
427
3.78
3.64
292
293
126
377
U- I Upflow Pilfer No. I
U-2 - >, No 2
D-l T n-Medio Filler No I
0-2 „ No 2
283
-------
Fig. 3.1.42 SS Removal Variation of the Upflow
Filter
Fig. 3.1.43 SS Removal Variation of the
Tri-Media Filter
2345
Captured SS (kg-ss/m2 )
3) Consiederation
i) Amount of SS captured
The amount of removed SS at the time of low turbidity (average influent
turbidity; 17.5 mg/E) and that at the time of high turbidity (average influent tur-
bidity; 40 mg/fi) were almost equal as for the upflow filter as indicated in Fig.3.1.44.
The value is 120 ~ 150 kg/30 m2 (4 ~ 5 kg/m2) (0.8 - 1.0 Ib/SF) in the
terminal head loss of 2.70 m.
With regard to the tri-media filter, while the SS removal amount was 30-70
kg/30 m2 (1.0 ~ 2.3 kg/m2) (0.2 ~ 0.5 Ib/SF) at the time of low turbidity (anth-
racite particle size; 1.22mm), the removal amount at the time of high turbidity
(particle size; 1.70mm) increased up to 90- 110 kg/30 m2 (3.0- 3.7 kg/m2) (0.6
- 0.8 Ib/SF), as shown in Fig. 3.1.45. The head loss distribution comparison in the
case of anthracite size; 1.70 mm and 1.22mm of Fig. 3.1.40 indicates that the
increase of head loss was limited to the anthracite layer when the particle size was
1.22mm, but the head loss increase reaches the sand layer when it was 2.70mm.
Therefore, in the filter media of the anthracite particle size of 1.22 mm, SS removal
was small and in the case of the particle size of 1.70 mm, the anthracite layer and
the sand layer works effectively for SS removal so that the larger part of SS was
removed. Amount of SS removal of tri-media filter is rather inferior to that of
upflow filter: about 70 - 80%.
284
-------
Fig. 3.1.44 SS Removal of the Upflow Filter Fig. 3.1.45 SS Removal of the Tri-Media Filter
(200 m/day) (200 m/day)
Sao,
E
' High Turbid I ty
i Low Turbid i ty
IOO ISO 200
Captured SS f hg-ss/30 m2 }
Anthracite I. 70
1.20
Captured b s 'kg/30m3]
ii) Effluent turbidity
Fig. 3.1.46 presents the turbidity of influent and effluent investigated every
one hour. The turbidity of effluent from the both filters were higher at the start of
filtration than those of later stage of the runs. The degrees of this deterioration of
effluent turbidity were greater in the tri-media filter and also the time required for
recovering the stable turbidity is longer in the tri-media filter.
Fig. 3.1.46 Turbidity of Filtrate to the Influent Containing High Turbidity
(Filter Rate 200 m/day)
Inf lueni Tur bidity
Effluent Turbidity
(NoJUpnow Filter)
Effluent Turbidity
(No.2Upfldw Filter)
Effluent Turbidity
(No,l Tri-media Filter)
Effluent Turbidity
(No,2Tri-media Filter)
(.013
I 15 18
i Ooy
21 0 3 6 9 12 15 18 21 0 3 6 9 12 15 18 21 (Hour)
5th Day 6th Day
iii) Filter bed condition
No variation was observed in the outer appearance of the filter bed against the
high turbidity influent as to the upflow filter. In this experiment six tests were
executed and the head loss was augmented to above 1.70 m, but no break of the bed
occurred during these runs.
285
-------
In the tri-media filter, however, SS accumulated on the anthracite surface
invades along the wall face and the filter bed condition deteriorates.
Since the general washing method could not recover the original condition of
the bed and the following operations became necessary.
i. The backwash water containing chlorine of high concentration (sodium hypo-
chlorite 500 mg/£) was sent to the filter and the chlorinated water was stored to the
level right below the trough.
ii. Air blow is performed. The chlorine remaining in the filter bed disappears in
15 min. of continuous air blow.
iii. The water staying in the upper layer of anthracite was lowered down to the
filter bed by opening the drainage valve and again the air blow was performed.
iv. SS dissociated from the filter bed was washed away by the backwash water.
The operations of i ~ iv are repeated in correspondence to the necessity.
When much SS remained in the tri-media filter bed, the filter.could not suffi-
ciently fluidized during its washing and masses of SS accumulated in a certain part
of the bed or the surface of anthracite layer piled up. However this extreme deterio-
ration of filter bed condition did not cause any initial head loss increases. This was
because the influent passed through the SS accumulated part with of resistance than
other parts in the beginning of filtration. Thus, the effluent quality became worse
just after the filtration start as above described. It seemed that, after a while, the SS
accumulated part became densely packed, and the effluent quality stabilized.
Therefore, the best method to find the deterioration of filter bed condition is the
observation of surface of anthracite layer after water drainage. When it was difficult
to remove SS remained in the filter bed, the hand operation of breaking masses of
SS with a bar during the backwash along with the above i ~ iv was also effective.
The backwash method executed once a day was changed to that shown in Fig.
3.1.23 so as to treat the high turbidity influent.
(13) Filtration through the upflow filter at the large flow fluctuation
,) Experiment method
Fig. 3.1.47 Wastewater Flow Variation in the Treatment Plant (1974)
35000,
_ 30000
-§20pOO$5i
I 5000
: I 0.000
5000
-•-•- D ecember - Februor y
-<*-°- March -May
-X-K- June-August
•**• September-November
— Average
&*J>.
910 II 1213 1415 1617 18 1920212223241 2345678
Time (hour)
286
-------
Table 3.1.15 Flow Fluctuation Curve (No. 1)
9
10
I I
I 2
13
I 4
15
1 6
I 7
i e
1 9
20
2 1
22
23
24
1
2
3
4
5
6
r
e
Flow Rote
ImVhrT
356
45O
5 IS
553
544
506
459
431
413
422
431
450
469
469
469
450
403
328
281
234
210
197
188
244
Filler Rote
(m/doy)
285
360
412.5
4425
435
405
3675
345
330
337.5
345
360
375
375
375
360
3225
2625
225
187.5
168
1 575
ISO
195
Observed Value
Flow Rate
( m3 / h r I
345
452
560
520
-
420
412
410
420
452
480
480
480
452
306
-
205
168
150
216
Filter Rate
(m/doyj
276
36 1 .6
448
41 6
336
329.6
328
336
361.6
384
384
384
361.6
244.8
-
164
-
134.4
120
172.8
The maximum filtration rate was taken at 443 m/day which was maximum
filtration rate possible for one filter operation. Applying this rate for the annually
averaged maximum flow rate per hour of a flow fluctuation pattern in a certain
sewage treatment plant shown in Fig. 3.1.47, the flow rate of the other time was
determined in correspondence with this pattern. Thus, the supposed value of flow
fluctuation curve (No. 1) in Table 3.1.15 was obtained. The ratio of the maximum
to the minimum flow was 3.7 : 1. The control of flow rate against the supposed
value was executed by changing the water level of the raw water conduit. The water
level change of the raw water conduit was performed with changing the setting of
influent flow regulator sending the signal to the influent flow control valve by
remote control. The signals to this regulator was sent by the flow indicator which
could send 96 types of analogue signals in 24 hours. Accordingly, the signal was
cascade changed once 15 minutes. The water level is determined on the following
equation;
(3)
where,
a
C
Ho
H
= OaV2g(H-Ho)
Bellmouth sectional area 0.0707 m2 ( 300 m/m)
Flow coefficient
Bellmouth height (height above the bottom of influent conduit)
Water level of influent conduit
Gravity acceleration
Flow (m3/sec.)
287
-------
Based on the water levels (H,, H2) in the two flows (Q,, Q2) different to each
other, C and Ho of each filters determined as follows;
No. 1 filter No. 2 filter
C 0.7725 0.7620
Ho 0.203m 7.196m
Flow was measured by electro-magnetic flow meter and water level by water
level meter of air purge type.
The experiment of large flow fluctuation was to be executed in No. 2 filter and
the enumeration equation of flow was obtained;
Q = 0.7725 x 0.0707 x 2 x 9.8 (H-7.196)
Q
= 7.196
)2
0.2385
When the unit of Q is m3/H,
H = 7.196 J-' Q ^
(4)
(5)
858.6'
The observed values in Table 3.1.15 were obtained by calculating the water
level for each flows with the equation (5), setting it in the flow indicator and meas-
uring the actual flow.
The experiment was conducted in the flow variation pattern of this observed
value. Flow variation pattern of the calculated value and the observed value are
presented in Fig. 3.1.48.
Fig. 3.1.48 Large Flow Fluctuation Pattern
"300
ll
I! 200
i_
ICO
--x x~- Calculated Value
—o—o Observed Value
9 10 II 12 13 14 15 16 17 18 19 20 21 22 23 24 I 234 567 89
Time ( hour)
37 41 45 49 53 57 61 65 69 7377 81 85 89 93 | 5 9 (3 17 21 26 29 33 37
Dial No of Flow Designer
2)
Experiment result
This experiment was performed totally for ten times as shown in Table 3.1.16.
The break phenomena occurred three times of these ten. In RUN-2 and 3 it occur-
red when the flow increased rapidly at the high head loss. In RUN-4, it occurred
when the normal backwash was not performed due to the fault of the pinboard
timer. In RUN-5 ~ 7, the head loss did not rise up to above 1.70 m within 24 hours.
When the head loss rises above 1.70 m, the stress was observed in the grid and the
filter bed got into the break zone condition status. In RUN-8 ~ 10, though the head
loss was above 1.70 m, no break occurred because the period of rapid flow increase
was applied for the filtration start. Therefore, it was found that the break of the
upflow filter occurred when the head loss was above 1.70 m and the flow increased
suddenly. Incidentally, the break might be caused also by those instantaneous
288
-------
change of flow rate by means of cascade control. It, however, is now being investi-
gated on permissible range of flow fluctuation. The hourly variation of the head
loss, the flow rate and the influent quality for every run is shown in Fig. 3.1.49
through 3.1.53.
Table 3.1.16 Experiment on Large Fluctuation
of Flow to Upflow Filter No. 2
Expenm
NO,
'
2
3
4
5
6
7
6
9
(9)
IO
Date
75KV2I 9-45-KV2I 17:30
10/22 IS 15-K>22 835
10/22 ro-is-io/zss^s
10/23 1445-KV24 2)45
10/28 6-00*0/29 I5-.I5
10/29 15OO-IO/30 BXX)
10/30 I7-QOHO/3I I7OO
10/31 B-.I5-II/1 1300
ll/l I4OO-I1/5 1605
UI/4 9 15-11/5 16-15)
11^ I&00-M/6 I&20
Filter Run
Time
hr.: m i n )
7 45
13 50
23 3O
12 00
24. 15
24 00
24-00
18' 45
98:15
(31:00)
22.20
Turbidlty(overage)
Influent
(mg/1 1
31
32
10
23
7
9
1 2
1 6
7
(7)
1 7.5
W/efj
1
1
0
1.3
I
1
1
1
•cl
«l )
I
Max Heac
L«?
2.50
2.90
2ft 6
2.40
0.80
093
1.20
2.64
261
(2.61)
d»v<3.00
Observa
-tlons
Breakthr
-ough at
the HeoO
Loss ol
2J90
Breakthr
-ough at
the Head
L°2"46f
Breokihr
-oughof
the Head
Lois of
2.40
Incompl
-lere bock
wash)
Airwoter
mixing
wash)
*w.l 14.00
-Nov. 4
09-15'
Constant
i»
Fig. 3.1.49 Experiments on Large Flow
Fluctuation No. 1, No. 2
Fig. 3.1.50 Experiment on Large Flow
Fluctuation No. 3
!•
— Filler Rate
-*— Influent Tur bid
-—Effluent Turbidft
500 _
40O"-
E
300 =
(E
ZOO •
\L
IOO
—~- Filter Rdie
- Influent Turbidity
- Effluent Turbidity
-•4- Head Lois
D II E S H CI6 1718 B 20 21 22 23 24 I 23456789 (Hour)
289
-------
Fig. 3.1.51 Experiment on Large Flow Fluctua-
tion No. 4 (Incomplete Washing)
Fig. 3.1.52 Experiment on Large Flow
Fluctuation No. 8
40 -j
I30
£20-
— Filler Roie
—— Influeni Turbiduy
—— E(flueni TurDidity
-•-*-- Head Loss
IS 16 17
Oct 23,19^5
20 21 22 23 0 I 2 3{Hour>
rime Oci24
—- Filler Role
^Influent Turbidity ^
-!-Effluenl Turbidity -V
Heod Loss .0<%
^f-'
*»"«*
300^
£
200 5
a
100 £
18 19 2O 21 22 23 0 I ? 3 4 5 6 7 G 9 10 II 12 !3(Hour)
OCI3I Novl Time
Fig. 3.1.53 Experiment on Large Flow Fluctuation No. 10
(14) Filtration through the upflow filter at the small flow fluctuation
1) Experiment method
Fig. 3.1.54 Small Flow Fluctuation Pattern
--<—K-- Colculored Value
—<^-° Observed Value (No.I)
—•—•— Observed Value ( No.2 )
IOO
0
9 10 II 12 13 14 15 16 17 18 19 20 21 22 23 24 I 234 56769
Hour
No 37 41 4549535761 65 67 73 7781 85 8993 I 5 9 13 17 21 25 29 3337
Diol No.of Flow Set-up
0 I 2 3 4 5 6 7 8 9 10 II 12 13 W 15 16 17 18 B 2021 2223
Absolute Hour
290
-------
The maximum flow of 300 m/day (the maximum filter rate of two filters
operation) was applied for the peak flow of Fig. 3.1.47 and the filter rate of each
time zone was obtained in a similar manner as in the foregoing experiment and
presented in Fig. 3.1.54. A part of the filter rate could not lower as calculated
because of the limitation from facility construction and resulting in ratio between
the maximum and the minimum value in the actual flow rate of 2.4 : 1 (No. 1 up-
flow filter) and 2.3 : 1 (No. 2 upflow filter).
2) Experiment result
With regard to the low turbidity influent, 20 times of the experiment were
performed for No. 1 upflow filter and 24 times for No. 2 upflow filter, as shown
in Table 3.1.17 and 3.1.18. Some hourly variations of them were presented in
Fig. 3.1.55 ~ 3.1.57. These results prove that when the head loss is below 1.7 m,
breaks does not occur in spite of the variation of the flow velocity.
Table 3.1.17 Experiment on Small Fluctuation
of Flow to Upflow Filter No. 1
Table 3.1.18 Experiment on Small Fluctuation
of Flow to Upflow Filter No. 2
Experlm
-enf
NO.
I
2
3
4
5
6
7
e
9
10
I [
12
13
I4
15
16
(7
ie
19
2O
21
Date
51-
1/21.18-53-1/23,16-22
1/23,16:53-1/24,22:17
l/24£ JO6-I/26 ( 4 . 33
1/26, 5:23" I/27,IQ:45
1/27,1 1-35-1/28,17:09
1/28/7: 59-l/29,23--22
l/30p-13~l/3l, 5.46
1/31,6' 36~2/ 1, 12:OO
2/1,12:50 -2/2,18:15
2/219:06-2/4 , 0-41
2/4,1-31-2/5,7:07
2/5,7:57-2/6,13-30
2/6J4'-2l-2/7,l9-42
2>T£O-32~2/9 , 1 : 54
2/9,2-44- 2/10.8- OS
2/t£ 59-2/11,1423
2/1 M5:i3~ 2/I2£O-3a
2/^22 128-2/W, 3--02
2/W, 3 35-2/15, 9:27
2/I5JO-1 7-2/1 6,15 39
4/9,16 X>5-4/O, 6 38
Filler Run
Time
4322
29.24
29^25
29:22
29-34
29:23
29:33
2* 24
29:25
29:35
29:36
29-33
29-21
2922
29-24
29=24
29:25
2934
2934
29:22
14-33
Turbidity( overage)
"t'rnW
9
4
3
2
3
3
4
3
4
4
5
7
5
6
5
6
6
7
6
5
20
EWo7V/
2.
I
1
1
1
1
I
1
1
I
1
2
1
1
1
1
1
,
1
1
2
Max. Head
Loss
Q75
0.58
a 67
0.68
0.61
0.56
0.67
O-62
0 61
0.61
0.66
0.69
0.59
0.64
0.62
061
059
0-67
O63
0.59
1.90
Observo
-flons
Break
Occurred
laperim
•enf
NO.
1
2
3
4
5
6
7
e
9
IO
1 1
12
13
14
15
16
I 7
ie
19
20
2 1
22
23
24
25
Dare
51-
l/2Y7-O4-l/23,2O-45
1/2321:50-1/25, 2 45
1/25,359-1/26, 8 3O
1/26,927-1/27,14 25
1/27,1 5U7-UZ6, 20 U3
1/28,2 IS6-1/30, 3:40
^30, 4-32-1/3 1 , 9 32
1/3 1,1023-2/1 , I5'I2
2/1,1603-2/2, 2O53
2/2,2144-3**, 245
2/4.3:36-^5, 758
2/5,8^49-2^, 436
2-€,5-.27-2/7 , I'I6
2/7, 2 --08-2/7, 2151
2/7,22 42-2-3, IS34
2/8,19.25-2/9, I5'O7
2/9,15-59-2/10, 11-49
2^0^40-2/11, 8:26
2/11, 9:17-2/12, 5:04
2/1 2, 536 -2/13, C44
2A3, 236 -2/13, 22. 18
2/l325O9-e/W, 1 9:OO
2/14,1951-2/15, 15.34
2/15,16-25-2/16, 12: 15
4/320.3O-4/9, 1 1:35
Filter Run
(hrmln)
49:54
28:55
28 46
28:58
28 '56
30.35
39 00
28 49
28 SO
29:01
28:22
19.47
1 9 49
19:43
19.52
19 42
19. 5O
19 46
1 9-47
1 9 48
1 942
1 9.51
19 43
1 9. 5O
15.05
Turbldlryfoverage)
'TrW
9
5
3
2
3
3
3
3
4
4
5
8
5
5
6
5
6
6
6
6
6
6
6
5
21
Euvw
5
4
2
2
2
2
3
3
3
3
3
4
2
2
J
2
2
2
I
2
2
2
2
2
3,5
Mo, Head
LfS,',
0-9O
079
Q83
0.70
0.66
O7B
083
069
065
Q75
073
0.77
Q67
0,61
060
063
062
064
0£5
066
0.57
Q59
0.6O
Q6I
2.70
Observe
•floni
291
-------
Fig. 3.1.55 Experiment on Small Flow
Fluctuation (No. 2 Upflow
Filter, Low Turbidity)
(m)
20,
— Filter Role
-<- Influent Turbidiry
-— Effluent Turbidity
'•*" Head Loss
30O™
E
200 £
ir
100 2
3579
Jon25
13 15 17 19 Zl 23 I 357 9 (Hour)
Jon 26
Fig. 3.1.56 Experiment on Small Flow
Fluctuation (No. 1 Upflow
Filter, Middle Turbidity)
5O|2p
30
-§20
J3
3
"-IO
Filler Rote
Influenl Turbidity
Effluent Turbidity
Heod Loss
IS I7 © 19 20 21 22 23 0 I 2 3
April 9, I975 Time
400
3001
E
200 £
Fig. 3.1.57 Experiment on Small Flow Fluctuation
(No. 2 Upflow Filter, Middle Turbidity)
— Filter Role .^
-— Influent Turbidity o* V
-— Effluent Turbidity
-------
(16) Comparison of turbidity meters for automatic measurement
1) Experiment method
The following three types of turbidity meters were employed in this experi-
ment;
1. Turbidity meter, Hokushin Electric Works (N), W301-WLS301 (Open liquid
surface scattered light method)
2. Ultrasonic washing type turbidity transmitter, Yokokawa Electrics (Y), TYPE
8562 (Scattered light and permeable light operation system)
3. Turbidity meter, Swiss Sigrist (S), UP52, (permeable light and standard light
comparison system)
Secondary settled sludge was mixed into the secondary effluent (SS lOmg/C)
from March 3 till April 10 of 1976 so as to increase the turbidity and then the indi-
cated values by the above three turbidity meters were compared. Sludge was added
four times on March 3, April 13, April 5 and April 9 ~ 10 and the each turbidities
are indicated in Fig. 3.1.58 ~ 3.1.62. The indicated value of each turbidity meters
in the secondary effluent are indicated in Fig. 3.1.63.
Fig. 3.1.58 Comparison of Turbidity Meter
(High Turbidity)
Morch 3 . I976
Fig. 3.1.60 Comparison of Turbidity Meter
(High Turbidity)
-50,
a>
E
"40
April 5, I976
17 6 15 14 [3 12 II 10 9(Hour)
Fig. 3.1.59 Comparison of Turbidity Meter
(High Turbidity)
Fig. 3.1.61 Comparison of Turbidity Meter
(Fluctuation of N Company Base)
30
20
10-
April 9, 1976
23 22 21 20 19
Time
293
-------
Fig. 3.1.62 Comparison of Turbidity Meter
(Fluctuation of N Company Base)
Fig. 3.1.63 Comparison of Turbidity Meter
(Low Turbidity)
April 10, I976
Morch 3. I976
Apn ] 8. I976
a 8 7 6 12
10 9 SlHour)
2) Experiment result
i) The indicated value of N and S are stable at the time of low turbidity (below
10 mg/2). The indicated value of Y has an irregular fluctuation. (Fig. 3.1.63)
ii) S and Y are excellent in the longtime stability. In case of N, the fluctuation of
the base is found in Fig. 3.1.63. This is because SS is accumulated in the bottom of
the tube forming the rest water surface, the water depth becomes shallow and
irregular reflected lights augment. On April 10, the turbidity of N rose, finally
reached 100% and did never return. When SS accumulated at the bottom of the
tube was removed by flashing with city water, it became to indicate the normal
value.
iii) S was the most excellent, N was the second and Y was the worse in the range of
turbidity fluctuation.
(17) Particle size distribution in the effluent
Particle size distribution of SS contained in the secondary effluent and the
filtered water was measured by HIAC fine grain meter and shown in Fig. 3.1.64 ~
3.1.66. Fig. 3.1.64 shows about the filter rate of effluent from the usual secondary
treatment plant at the filter rate of 500 m/day with the inlet turbidity of 14 mg/e
and Fig. 3.1.65 shows the filtered effluent at the filter rate of 200 m/day which the
secondary drained sludge was mixed into the secondary effluent. The number of
particles sized below 10 jum was not largely different between the mixed raw waste-
water and the secondary effluent, but for the particles of the size above 10/urn the
number was much larger in the mixed raw wastewater. In both cases, the number
contained in the filtered effluent was smaller than in the influent in the range of the
particle size above 7.5/urn. This shows that the particle size of SS removed by
filtration is above 1.5 urn. SS above 7.5/um of the carry-over from the secondary
clarifier can also be removed.
294
-------
Fig. 3.1.64 Particle Size Distribution (Middle
Turbidity)
Fig. 3.1.65 Particle Size Distribution (High
Turbidity)
46 I25
No.SUpflow Filter
Influent No. 1 Trl Mcd
]rri rn
i n
i y
Fll >e
I5000-,
-
E
IOOOO
5000
0
V ^S "~
^ r^
r^ ^
^ ^ d
3 F Iter
9000"
80 OO
Rote 5OOm/doy
31
_7000
E
o
6OOO
5000.
4000
3000
2000
IOOO
bi
Sep. II, 1975
No.lUptlow Filter
nfluent ' No.2
n E
ul
i 1 ti_
30 0-i
1
LJ
1.0 (
Filter Rote 200
~
N
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
1 —
^-
\
\
\
\
\
\
\
\
\
\
-
frl-Medla
mg/ 1 )
Ti/doy
\
\
\
\
Filter
"1
1
-
^T_,
\l 1
•S.
^h
4-5 5-75 75-10 (0-15
Particle Size
4-5 5-75 7,5-IO IO-I5 15 -I50(/>m)
Fig. 3.1.66 Particle Size Distribution (Low Turbidity)
2OOOO
I5OOO
e
^'OOOO
5OOO
0
^,
\
\
\
\
\
\:
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
t
pr
1
\
\
\
\
\
\
\
\
\
\
\
\^
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
\
7,
p
1976
—
S S
1 | Influent 3 3mq
^VJNolUpf low Filler 1.3
|" [NolTrimediQ Filter 2 Q
•^H
\
\
\
\
\
\
\
\
\ \T — i
\ \ VI ,
\ \ \h
\ \ o
\ \ Ci 1
5- 7 7- 10 10- 15 15 ( j
295
-------
(18) Boring investigation of upflow filter media
1) Method
As to the upflow filter operated continuously for two years after the intro-
duction of water, the boring investigation was performed on the filter media (two
places), all the filter sand were carried out and the investigations of the supporting
sand layer and the water nozzle were executed. This investigation had the purpose
of finding out the quantity of the foreign matters which was not removed by the
traveller screen (opening of 6 mm) mounted in the entrance of the raw water tank,
entered into the filter and caught in it.
2) Result
i) No foreign matter was found in the filter sand and the sand itself was clear.
ii) The particle size of the filter sand tends to become smaller along with the
operation.
iii) The foreign matters (vinyl strips etc.) in the supporting sand layer are slight and
tend not to be accumulated.
iv) Choking of water nozzles caused by the foreign matters contained in the in-
fluent was not observed.
3.1.3 SUMMARY
Coagulation-sedimentation filtration experiment and the comparison experi-
ment of the upflow filter and the downfiow filter have shown summarily the follow-
ings;
a. Coagulation-sedimentation filtration method is effective for the removal of
phosphorus, BOD and SS.
b. Direct filtration method is sufficient for only BOD and SS removal.
c. Flow proportion control method is enough for the alum addition to perform
the coagulation-sedimentation treatment.
d. Increase of the filter rate up to 500 m/day (8.5 GPM/SF) did not have any
adverse effect to the effluent quality and also to the systems operation.
e. No difference in the effluent quality was observed between the upflow and the
tri-media filter.
f. The average removals of SS and BOD were 90% and 80% respectively.
g. In this study, the optimum backwash procedures have been found for the both
filter systems.
h. Amounts of SS removed were about 5 kg/m2 (1.0 Ib/SF) through the upflow
filter and about 3.7 kg/m2 (0.8 Ib/SF) through the tri-media filter (anthracite
particle size of 1.70 mm).
i. The supporting gravels of the upflow filter effectively functioned as filter
media for SS removal.
j. Breakthrough problem in the upflow filter during constant flow filtration was
perfectly solved by adopting the adequate washing method.
k. When Hows rapidly fluctuate during high head loss stage of filtration runs, sand
bed break may occur. However, this can be overcome and prevented by countering
operational procedures.
1. The anthracite of about 1.7mm in its effective size is advantageous to be
employed in the tri-media filter.
296
-------
m. The practical flow rate of the upflow filter was larger than that of the tri-media
filter. This realizes that the upflow filter has the larger SS removal capacity from a
practical point of view.
n. Removal of E. coli can be expected through filtration.
o. The upflow filter has an advantage that the observation of the effluent quality
and that flying out of generated chironomus can be prevented by the filter bed.
p. SS removal at the filtration of high turbidity influent is almost equal to that at
low turbidity but the backwash must be carefully conducted.
q. The size of particles that can be removed by filtration is above 7 nm.
r. Choking of water nozzles was not observed in the upflow filter and the sup-
porting sand layer was also kept clear.
297
-------
3.2 FILTRATION STUDY AT THE KYOTO PILOT PLANT
The fallowings are a summary on the suspended solid removal by filter and
carbon contractor at the Kyoto pilot plant.
The section - 3.1.1 - deals with the solid removal by filter of secondary
effluent and alum precipitated effluent under varying influent flow. The sewage
inflow into a treatment plant varies every moment. Its variation is extremely great
from a low in the night on dry weather to a high on storm weather.
There are two possible ways to meet the inflow variation — one, the constant
filtration with flow equalization ponds and the other, the varying filtration allowing
the influent flow variation. Because of a omission of a flow equalization pond, the
varying filtration is superior to the constant filtration, if there is no great difference
as to the quality of effluent and the suspended solid loading between the two.
This report sums up the results from October, 1975 to March, 1976.
The section — 3.1.2 — is a study on the possibility of removing both organics
and solids by granular carbon. The influents for testing here are filtered secondary
effluent, secondary effluent and tertiary alum precipitated effluent.
In this method, there are questions as mentioned below.
1) Is the necessary filtration run length expected by carbon layer?
2) Is the suspended solids in the effluent satisfactory?
3) Is there a drop in organic removal efficiency of carbon by accumulated solids
on the surface or in the micropore of carbon?
4) Is there a drop in carbon regeneration efficiency by accumulated solids on the
surface or in the micropore of carbon?
The feasibility of this method could be judged when the necessary information
is obtained. There had been no detailed report on this method in this country.
Then the Public Works Research Institute began the study on this method on
November 8, 1976, by using carbon contractors at the Kyoto pilot plant.
This report is an interim report summing up operational results in the two
month period from November to December, 1976, Some data obtained on the
questions, No. 1, 2, 3 is contained in this report. A study on the question No. 4 is
planned for February, 1977.
298
-------
3.2.1 SOLID REMOVAL BY FILTER UNDER VARYING FLOW
a. Experimental Procedure
Table 3.2.1 shows the specifications of the gravity, down-flow type filter used
for this experiment at the Kyoto pilot plant. There are two filters of the same
specifications, one is for the secondary effluent, and the other is for the effluent
from alum precipitation.
Table 3.2.1 Specification of Filter
Filter
Surface Area (m2)
1 .0 x 1 .2 =
1.2
Filter Media
Grain
Size
Depth
(mm)
Anthracite
Sand
Anthracite
Sand
Total
E.S. (mm)
U.C. (mm)
E.S. (mm)
U.C. (mm)
1.62
1.33
0.61
1.26
625
375
1,000
Support Media
Grain Size (mm)
19.1-12.7
12.7 -6.73
6.73-3.36
3.36-2.00
Total
Depth (mm)
50
50
50
50
200
A flow-rate pattern transmitter is set to give flow variation. The circuit for
controlling the inflow to the filter consists of two elements. One is the feedforward
control of revolution numbers of the roots pump connected to the effluent pipe of
the filter. The control works by electric signals from the above mentioned flow-rate
pattern transmitter. The other is the feedback control by electric signals from the
level meter, which is set on the triangle weir for the effluent flow measuring.
299
-------
Fig. 3.2.1 shows the flow variation used for this experiment. The variation
represents a typical pattern of the inflow into the Toba Sewage Treatment Plant
where the pilot plant is located.
Fig. 3.2.1 Flow Variation
o
a
c
o
Average
—i—
10
—i—
12
—r~
14
—i—
16
18 20 22
24
Time
1
2
3
4
5
6
Filtration
rate ratio
0.832
0.731
0.668
0.606
0.534
0.459
Time
7
8
9
10
11
12
Filtration
rate ratio
0.616
0.721
0.904
1.242
1.301
1.301
Time
13
14
15
16
17
18
Filtration
rate ratio
1.281
1.278
1.275
1.294
1.265
1.268
Time
19
20
21
22
23
24
Filtration
rate ratio
1.248
1.147
1.058
1.058
0.983
0.960
The filtration is terminated when the total head loss reaches 3 meters.
The turbidity in both influent and effluent was measured continuously by the
surface-scatter type turbidimeter and then the turbidity was converted into suspend-
ed solids through the relation of suspended solids to turbidity shown in Fig. 3.2.2
and Fig. 3.2.3.
300
-------
20
15
en
oo
10
Fig. 3.2.2 Turbidity ~ SS (Secondary Effluent and Its
Filter Effluent)
O Secondary effluent
• Filter effluent of secondary effluent
SS = 0.976 • Turbidity
SS = 0.898 • Turbidity
5 10 15
Turbidity (mg/C)
20
Fig. 3.2.3 Turbidity ~ SS (Alum Precipitation Effluent
and Its Filter Effluent
O Effluent from
Alum Precipitation
• Filter Effluent of
Alum Precipitation
Effluent
10 15 20
Turbidity (mg/K)
301
-------
In discussing the experimental results, suspended solids are calculated from an
average turbidity in every one hour from the beginning to the end of each case of
filtration (a weighted average with filtration flow rate in the case of varying filtra-
tion). And the suspended solid loading is expressed by [g-SS captured/m2 • sec-
tional area of filter] and obtained by average suspended solids in influent and
effluent, filtration run length and filtration flow rate.
The total head loss was measured continuously by the level meter and the head
loss in the filter bed was measured at 10:00 and 16:00 at the depths of 10, 30, 50,
75, 100 cm from the surface of filter media.
The washing of a filter consisted of nine minutes of surface washing (0.2 m/
minute), nine minutes of back washing (1.03 m/minute) and seven minute overlap of
the two washings.
The expansion ratio of media by backwashing was set at 20%. And the washing
water volume needed for above condition was 11.2m3.
b. Filtration of Secondary Effluent
Fig. 3.2.4 is the relationship between suspended solids in the influent and
effluent. It shows that suspended solids in the effluent increase with the increase of
those in the influent. Also seen in the figure is the presence of two groups with
distinct difference in filtration flow rates. Group-A is of the rates of 180, 300,
420 m/day by constant filtration. Group-B is of the rate of 500 m/day by constant
filtration and of the average rates by varying filtration of 300 m/day (flow rate
range, 138 ~ 390 m/day) and 420 m/day (flow rate range, 193 ~ 546 m/day).
Fig. 3.2.4 SS Removal by Filter
(Influent: Secondary Effluent)
c
u
3
5-
4-
3-
.S 2-
00
y = 0.381 -x+ 1.006
r = 0.969
N= 12
= 0.387-x
r = 0.931
N= 11
0.020
o Constant 180 m/day
n Constant 300 m/day
AConstant 420 m/day
•Constant 500 m/day
• Varying 300 m/day
A Varying 420 m/day
—i—
11
—i—
10
12 13
SS in influent (mg/C)
302
-------
When the relationship of suspended solids in the influent and the effluent in each
group is assumed linear, the regression lines obtained are:
Group-A [SS in effluent (mg/C)] = 0.387 x [SS in influent (mg/C)] + 0.020 . . (1)
Group-B [SS in effluent (mg/C)] = 0.381 x [SS in influent (mg/£)] + 1.006 . . (2)
The SS removal of Group-A obtained by eq. (1) is about 61% regardless of the
SS in the influent. The gradient of eq. (2) almost equals to that of eq. (1). However,
the intercept of eq. (1) is about zero against about 1 mg/£ of eq. (2). This means
that the SS in the effluent of Group-B is by about 1 mg/C higher than that of Group-
A regardless of the SS in the influent. Accordingly, in Group-B, the SS removal as
calcurated by eq. (2) increases with the increase of the SS in the influent, standing at
42, 49, 54% respectively against the SS in the influent of 5,8, 12 mg/C.
For a comparison between constant filtration and varying filtration, take the
filtration flow rate of 300, 420 m/day common to the two methods. In this case,
the SS of the effluent by varying filtration is estimated to be higher by about 1 mg/C
than that of the effluent by constant filtration when the SS of the influent is the
same. Because constant filtration belongs to Group-A and varying filtration to
Group-B. However, it must be noted that varying filtration with an average rate of
300 m/day has the maximum rate of 391 m/day. Therefore, when only filtration
rates are taken into consideration, it is hard to conclude that the effluent quality by
varying filtration is worse than that by constant filtration. It is considered that the
true problem lies in the change of filtration flow rate itself.
Fig. 3.2.5 shows the SS loading in the case of the total head loss set at 3 m.
The SS loading increases with the increase of the SS in the influent. However, at the
flow rate of 500 m/day, this tendency ends when SS in the influent exceed 10 mg/C.
The SS loading also differs with the change in filtration flow rates. The readings at
the rates of 180, 500 m/day are evidently smaller than those at the rates of 300,
420 m/day. For example, when the SS in the influent is 7.5 mg/C, the SS loading
for each of the rates of 180, 300, 420, 500 m/day is about 2,300, 3,500, 3,500 and
2,300 g/m2 respectively.
Fig. 3.2.5 SS Loading of Filter
(Influent: Secondary Effluent)
4,000
3,000 -
3
.f 2,000 -
1,000 -
o Constant 180 m/day
D Constant 300 m/day
A Constant 420 m/day
• Constant 500 m/day
• Varying 300 m/day
A Varying 420 m/day
5 6 7 8 9
SS in influent (mg/f)
10 11
12 13
303
-------
Fig. 3.2.6 shows an example of the relationship between solids in the washing
waste and the washing time being obtained by the same procedure mentioned before.
(Fig. 3.2.7) The SS loading obtained from Fig. 3.2.6 is 2,700 g/m2. This value
should agree with the SS loading captured by the filtration. However the former
loading exceeds loading about 20% more than the latter one (2,300 g/m2). Only
one example is shown here. But more study is planned for turbidity measuring of
washing waste.
Fig. 3.2.6 Filter Washing
5= C
~
rt
2 i
1
0
800
700 -
600.
O<>
~5o
500-
c
'4
:fl
C
C/3
400 -
300-
200-
100-
Surface
washing
(0.2 m/min.)
Surface and back washing (1 .23 m/min.)
/• j Q^ -
1_
0 1
34567
Washing time (min.)
10 11
304
-------
Fig. 3.2.7 Turbidity ~ SS (Filter Washing Waste)
Turbidity 150
SS= 11.87 xTurb. +31.90
r = 0.917
Turbidity > 150
SS = 10 t1
r = 0.947
100 200 300 400
Turbidity (mg/C)
500
600
Fig. 3.2.8 is the relationship between suspended solids in the influent and the
filtered volume. It shows that the filtered volume by constant filtration and varying
filtration is almost the same at the flow rates of 300, 420 m/day. Accordingly, at
the rates of 300, 420 m/day, the comparison between the SS loading by constant
filtration and that by varying filtration is reduced to the comparison of the amount
of SS removed. For example, in the case of 7.5 mg/£ of SS in the influent, the
amount of SS removed obtained from Fig. 3.2.4, are 4.6 mg/C for constant filtration
and 3.6 mg/2 for varying filtration. Therefore, the SS loading by varying filtration
at the rates of 300, 420 m/day is about 80% of that by constant filtration (3.6/4.6 =
0.78).
305
-------
Fig. 3.2.8 Filtered Volume
(Influent: Secondary Effluent)
"E
m
E
S""*"
£
"o
13
£
£
1,200
1,000 -
800-
600-
400 -
200-
0
A
ADA A
°4
• _
o • D •
00 •
o Constant 180 m/day
n Constant 300 m/day * 9
A Constant 420 m/day • Varying 300 m/day
• Constant 500 m/day A Varying 420 m/day
1 1 1 1 1 i i i i i i i i
31 234567 8 9 10 11 12 K
SS in influent
Fig. 3.2.9 gives the relationship between bed depth and the average increase
ratio of the head loss in filter beds during constant filtration. The head loss increase
ratio here is expressed by the ratio of the value of head loss minus initial head loss at
a selected depth of filter bed against the similarly obtained value at the filter media
depth of 1,000 mm. The figure shows considerably difference existing
in the forms of suspended solids capturing, depending on filtration flow rates.
At the rate of 180 m/day, the form of filtration is the typical surface filtration
with the head loss increase ratio standing at 78% in the anthracite surface layer and
at a mere 1.5% in the anthracite-sand border and sand layers combined. At the rate
of 300 m/day, the head loss increase ratio is still fairly high at 64% in the anthracite
surface layer, but the ratios are almost uniform in the layers below. At the flow rate
of 420 m/day, the ratio drops to 41% in the anthracite surface layer and the per-
centage is 22 in the anthracite-sand border, indicating that solids are removed more
uniformly in every filter bed layer than in other rates. In the case of 500 m/day, the
head loss increase ratio in the anthracite layer becomes small, while the ratio stands
at 54% in the anthracite-sand border layer.
The finginds would allow the estimation that filtration of secondary effluent
by the filter media composition used this experiment, depends on the surface layer
at the rate of 180 m/day, on all layers at the rate of 300 ~ 420 m/day and on the
sand layer at the rate of 500 m/day. Because of the reason mentioned above, it
seems, that the SS loading is small at the rate of 180 m/day, that the effluent quality
is a little bad and SS loading is also small at 500 m/day and that both effluent
quality and SS loading are good at the rates of 300 and 420 m/day.
306
-------
Fig. 3.2.9 Head Loss ~ Filter Media Depth (Influent : Secondary Effluent)
1}
'o
s
• _c
- c
.<
•o
c
on
0
10
20 -
30
1=
0
x 40 -
OH
U
•a
ra 5Q
•a
E
£60.
u.
70 -
80 .
90 -
100
X/X/////X///X/X//
^^^^^ ?? 5%
y/^
A ».»
^
w
3.8%
f
1.2%
Filtration rate
°-3% 180m/day
4! 4%
14.1%
9.5
21.8
13 -2
Filtration rate
420m/day
0 20 40 60 80 100 0 20 40 60 80 100 0 20 40 60 80 100 0 20 40 60 80 100
Increasing ratio of head loss (%)
-------
Hour-by-hour measurement of the head loss in filter beds in the varying filtra-
tion has not yet been carried out. In this way of filtration, an average speed of
420 m/day has the speed range from 193 to 546 m/day, thus covering all filtration
forms by constant filtration - the surface filtration, the in-depth filtration and the
sand layer filtration. The hourly change of head losses in the varying filtration will
be observed in the future. And the observation may explain the reason why the
effluent quality by varying filtration is worse than that by constant filtration.
Fig. 3.2.10 The Time When the Total Head Loss Reached 3 m
Cumulative frequency of the time when
the total head loss reached 3 m. (%)
to 4* <^ OO O
o o o o o o
N = 47
I | 1 I 1 1 1
47
62
68
68
68
70
81
85
91
100
till
§ 1
-\ 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 1 1 1 1 1 r
123 45 678 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hour)
Fig. 3.2.10 shows the rationship between, the time of filtration termination in
varying filtration and its cumulative frequency. The data used for this figure are not
limited to the results obtained in the period of this experiment. The filtration start
time was from 9:00 to 16:00. According to the figure, the times of the total head
loss reaching 3 meters are limited to the closing periods of filtration flow rate
increase and at the times of high filtration flow rate. Especially noteworthy is that
about half the filtration runs stop in the closing period of filtration flow rate
increase or within one hour from 9:00. See one example of varying filtration in
Fig. 3.2.11.
308
-------
Fig. 3.2.11 Varying Filtration
O
U,
600-
500-
400 -
300-
200 -
100-
3 -
A A Filtration rate
Total head loss (m)
Turbidity of influent (mg/8)
Turbidity of effluent (mg/fi)
12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76
Run length (hr.)
-------
The results above indicate the possibility that in varying filtration, filters reach
to the terminal head loss almost at the same time, during the time of influent flow
rate increase, and the necessary capacity can't be maintained. In such a case, wash-
ing of the filters at the time of low influent flow or other preventive means would
become necessary.
c. Filtration of Tertiary Alum Precipitated Effluent
Fig. 3.2.12 presents the relationship between suspended solids in the influent
and in the effluent. It shows that suspended solids in the effluent increase linearly
along with the increase of those in the effluent. And there is no great difference in
the effluent quality between constant filtration at the flow rates of 120 ~ 300m/
day and varying filtration at the rate of 180 m/day. The regression line obtained
from the figure is:
[SS in effluent (mg/B)] = 0.521 x [SS in influent (mg/B)] - 0.360 ... (3)
The SS removal obtained through eq. (3) is 66, 60, 55, 52, 50, 49% respectively
for each SS in the influent of 2, 3, 5, 10, 20, 30 mg/B. This means that the lower
the SS in the influent is, the greater the removal becomes.
Fig. 3.2.12 SS Removal by Filter (Influent: Effluent from Alum
Precipitation of Secondary Effluent)
16
14-
12-
10-
6-
4-
2-
0
y = 0.521-X-0.360
r= 0.987
N = 33
Constant 120m/day
0 Constant 180m/day
° Constant 300m/day
• Varying 180m/day
10 12 14 16 18 20 22 24 26 28 30 32
SS in influent (mg/C)
Fig. 3.2.13 shows the SS loading at the total head loss of 3 meters. The loading
increases with the increase of suspended solids in the influent. There also is no
evident difference in the SS loading between constant filtration at the rates of 120 ~
300 m/day and varying filtration at 180 m/day. The regression line is:
[SS loading (g/m2)] = 66 x [SS in influent (mg/B)] +320 (4)
310
-------
Fig. 3.2.13 SS Loading of Filter (Influent: Effluent from Alum
Precipitation of Secondary Effluent)
2,800
2,600 -
2,400 -
2,200 -
2,000 •
1,800
1,600 •
1,400 •
1,200 •
1,000 -
800 -
600 -
400 -
200 -
0
0
= 66x + 320
r= 0.927
N = 33
a Constant 120m/day
0 Constant 180m/day
° Constant 300m/day
• Varying 180m/day
10 12
14 16 18 20
SS in influent
22 24 26 28 30 32
Fig. 3.2.14 is the relationship between suspended solids in the influent and the
treated volume at the total head loss of 3 meters. The curve in the figure is calcu-
rated through eq. (3) and eq. (4) in accordance with the following equation.
Fig. 3.2.14 Filtered Volume (Influent: Effluent from Alum
Precipitation of Secondary Effluent)
400
300
200
100 •
u a o o n
a Constant I 20m/day
0 Constant I80m/day
D Constant 300m/day
• Varying I80m/day
10 12 14 16 18 20 22 24 26 28 30 32
SS in influent (mg/S)
311
-------
[SS loading (g/m2)]
, /• a / 2 M — |,uu njquiiis V6/1" j\
[Treated volume (m /m )] - ss influentrSS in effluent
(5)
L(g/m3)
L(g/m3)
The treated volume obtained by eq. (5) shows that the less suspended solids in
the influent are, the more steeply the treated volume increases below a point of
10 mg/C of suspended solids in the influent. Above the point, the decrease in the
treated volume caused by the increase in suspended solids in the influent is not very
sharp.
Judging from the data obtained under the conditions of this experiment, it can
be concluded that varying filtration is not less efficient than constant filtration in
terms of the effluent quality and the SS loading in the case of filtration of alum
precipitated effluent.
Fig. 3.2.15 shows the relationship between the filter media depth and the
average head loss increase ratio obtained from the head loss distribution in the filter
bed during constant filtration. The head loss increase ratio here means the same
as defined in a.
Fig. 3.2.15 Head Loss~ Filter Media Depth
(Influent: Effluent from Alum Precipitation of
Secondary Effluent)
0
10
20 -I
30
f.40
15 50
£
£60-1
70
80 -
90 -
100
6.4%
9.3%
3.1%
65.6%
15.6%
Filtration rate 120 m/day
7.7%
4.5%
3.0%
62.8%
22.0%
Filtration rate 180 m/day
0 20 40 60 80 100 0 20 40 60 80 100
Increasing ratio of head loss (%)
312
-------
According to the figure, the head loss increase is almost negligible in the anthra-
cite layer but it occurs in the anthracite-sand border layer, standing at 65.6% and
62.8% respectively for 120m/day and 180m/day of the filtration flow rate, or
almost 2/3. This means that most floe in the effluent from alum precipitation passes
through the anthracite layer and is captured by the sand layer. This tendency is
recognized even in the relatively low filtration flow rate of 120 and 180m/day.
Therefore, a conclusion is that anthracite with the effective size of 1.62 used for this
experiment is too large for the filtration of the alum precipitated effluent.
3.2.2 SOLID AND ORGANIC REMOVAL BY CARBON CONTACTOR
a. Experimental Procedure
The carbon contractors used for this experiment are the gravity, down flow
type contractors with a sectional area of 0.7 m x 1 m = '0.7 m2 The height of
carbon filled is 3 meters. The water level above the carbon is 2 m. The underdrain
is the Leopold Block.
There are six contractors, two each place in a series. Influents are filtered
secondary effluent for the No. 1 contactor, secondary effluent for the No. 3 con-
tractor and the tertiary alum precipitated effluent for the No. 5 contractor.
The carbon for the primary contractors (No. 1, 3, 5) is X-7000, which is
spherical carbon made of coal by Takeda Pharmaceutical Company Ltd,. The
carbons for the secondary contractors are Calgon-SGL for the No. 2 contractor,
Calgon-CAL for the No. 4 contractor and Takeda's Shirasagi for the No. 6 con-
tractor.
The primary contractors are for the study of suspended solid removal. X-7000
is used for them, because the X-7000 has a relatively large effective size (1.21 mm)
and a small uniformity coefficient (1.32) among brands of carbon now available on
the market. Table 3.2.2 points to considerable difference existing in the effective
size and the uniformity coefficient from one brand to the other. The choice of
different brands of carbon for the secondary contractors is for the continuation of
carbon regeneration experiments, which have already been conducted four times.
Table 3.2.2 Activated Carbons Used for the Experiment
Mesh
E.S. (mm)
U.C.
Total Surface (m3/g)
lodin Number (mg/g)
Methylene Blue Number
(mB/g)
Material
Shape
Takeda
X-7000
8x32
1.21
1.32
900- 1,200
950- 1,150
180-200
Coal
Spherical
Takeda
Shirasagi
8x 30
0.82
2.02
970
950
180
Coal
Crushed
Calgon
SGL
8x30
0.72
2.06
980
950
170
Coal
Crushed
Calgon
CAL
12x40
0.52
2.00
1,065
1,000
200
Coal
Crushed
313
-------
The filtration flow rate for the experiment is 240 m/day (LV = 10) in constant
filtration and 240 m/day on the average in varying filtration. The variation of vary-
ing filtration here is identical to that on Fig. 3.2.1. The run is terminated when the
total head loss reaches 5 m.
The suspended solids was obtained by measuring turbidity with the surface-
scatter type turbidimeter and feeding the turbidity to the equations on the relation-
ship between suspended solids and turbidity. The equations are (cf. Fig. 3.2.2,
3.2.3):
for secondary effluent
[SS (mg/£)] = 0.969 x [turbidity (mg/C)]
filter effluent of secondary, effluent contactor effluent of filtered secondary
effluent, contactor effluent of secondary effluent.
[SS mg/C)] = 0.878 x [turbidity (mg/C)]
effluent of alum precipitation
[SS (mg/£)] = 1.303 x [turbidity (mg/C)]
contactor effluent of alum precipitated effluent
[SS (mg/C)] - 0.975 x [turbidity (mg/C)]
Fig. 3.2.16 UV Absorbance ~ TOC
TOC = 24.95 x UV + 3.44
r = 0.907
N = 23
I " 1 1 1 1 r
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
UV absorbance
314
-------
The organics was obtained through the equation on the relations between TOC
and UV (254 mm) (cf. Fig. 3.2.16). The UV absorbance needed for the equation
was measured by the continuous UV monitor made by Tinsley Co., Ltd,. The
equation is:
TOC (mg/£) = 25.0 x UV + 3.44
The UV monitor is designed to measure the absorbance of visible rays too so as
to eraze the error resulting from the.presence of suspended solids by reducing the
visible rays absorbance from that of UV. Except for some special cases, measured
values for discussing the result are average values in every case of run.
b. Solid Removal
Fig. 3.2.17 gives the relationship of suspended solids in the influent for the
No. 3 contractor (secondary effluent) and in its effluent. The SS removal ratio is
independent of suspended solid concentration in the influent by both constant and
varying filtration. The ratio is about 58% in constant filtration against 49% in
varying filtration. Constant filtration attained a better removal by about 10% than
varying filtration. However, it is a matter for future problem whether this difference
is of any significance, because the two methods were tested at different times —
constant filtration in November and varying filtration in December.
Fig. 3.2.17 SS Removal by Carbon Contactor
(Influent: Secondary Effluent)
I
3 '
c 2-
00
t/1
1 -
0 Constant (N = 8)
y = 0.417-X
• Varying (N = 17)
y = 0.515-X
No. 3 Contactor
3456
SS in influent (mg/C)
9 10
The comparison between SS in the effluent from the No. 1 contractor (influent
- filtered secondary effluent) and that from the No. 3 contractor shows that the
No. 3 contractor is a little less efficient than the No. 1 contractor. But the differ-
ence was only 9%. The average SS in the effluent from the No. 1 contractor was
2.0mg/C against 2.2 mg/C in the effluent from the No. 3 contractor (Fig. 3.2.18).
Therefore, it seems that as far as suspended solid removal no major problem will
arise from omitting filter.
315
-------
Fig. 3.2.18 Comparison of SS between No. 1 Contactor Effluent
and No. 3 Contactor Effluent
2 £2-
II
N = 14
y=1.09-X
SS in No. 1 contactor effluent
(Influent: Filter effluent of secondary effluent)
Fig. 3.2.19 shows the relationship of suspended solids in the influent of the
No. 5 contractor (tertiary alum precipitated effluent) and in its effluent. When the
effluent from alum precipitation was treated by the contractor, no difference was
found with regard to the SS removal between constant and varying filtration with
about 62% in both methods. In the two months of experiment, the average SS was
11.8 mg/£ for the influent against 4.5 mg/£ for the effluent.
Fig. 3.2.19 SS Removal by Carbon Contactor
(Influent: Effluent from Alum Precipitation of
Secondary Effluent)
12
10
00
E
y = 0.381-
N = 23
o Constant
• Varying
SS in influent fmg/C)
316
-------
In most runs on the No. 3 contractor, washing was started before the total head
loss reaching five meters. It was only once that the SS loading was measured at the
point of the total head loss reaching five meters. However, it is possible to estimate
the SS loading of constant filtration through measured values on the rate of the head
loss against the SS loading on Fig. 3.2.21. And the value estimated is an average
3,700 g/m2 (2,100 ~ 4,600 g/m2) against average SS in the influent being 4.8 mg/£.
Fig. 3.2.20 SS Loading of Carbon Contactor
(Influent: Effluent from Alum Precipitation of
Secondary Effluent)
3000
S 2000
CO
c
1000 -
o Constant flow
• Varying flow
No. 5 Contactor
6 8 10 12 14
SS in influent (mg/8)
16 18
20
Fig. 3.2.20 shows the relationship of the SS loading to suspended solids in the
influent at the total head loss of 5 m in the No. 5 contractor (influent — tertiary
alum precipitated effluent). The SS loading rises with the increase of suspended
solids in the influent in constant filtration. The loading of varying filtration is too
limited to give any definite conclusion. But the value of varying filtration is esti-
mated to be smaller than in constant filtration.
Fig. 3.2.21 and 3.2.22 show the SS loading ratio under lower total head loss
than 5 m against 5 m. Fig. 3.2.21 gives results of the No. 3 contractor, while
Fig. 3.2.22 is those of the No. 5 contractor.
317
-------
Fig. 3.2.21 Total Head Loss ~ SS Loading Ratio
(Influent: Secondary Effluent)
100
90
80 -|
70
Si
T 60
CO
.3
40
30 -
20
10
0
No. 3 Contactor
0
2 3
Total head loss (m)
In the case of the No. 3 contractor using the secondary effluent as influent, the
SS loading goes up almost linearlly with the increase of the total head loss up to
3 m. But when the total head loss exceeds 3 m, the SS loading increasing ratio for
every unit total head loss drops sharply. About 90% of the SS loading at 5 m of the
total head loss is achieved by 3 m. This may probably mean that the filtration goes
into the complete surface filtration at the total head loss of about 3 m because of
accumurated suspended solids in the surface area of carbon. But it must be repeated
that there was only one case of the total head loss in the No. 3 contractor reaching
to 5 m. Fig. 3.2.21 shows the results of this single case. More study is needed to
know exactly about whether the downturn in the SS loading occurs at the total head
loss of 3 m or whether 90% of the SS loading at the head loss of 5 m is accomplished
already at the point of 3 m.
318
-------
Fig. 3.2.22 Total Head Loss- SS Loading Ratio
(Influent: Effluent from Alum Precipitation of
Secondary Effluent)
100
90 -
80 -
70 -
60 -
1 50 -
•2 40 J
30 -
20 -
10 -
0
0
• Average
No. 5 Contactor
2 3
Total head loss (m)
4
Any development of this kind did not happen in the No. 5 contractor for
which the effluent from alum precipitation was used as influent. The SS loading of
the contractor increased in keeping pace with the increase of the total head loss to
5 m, indicating the effective use of the total head loss. This also means that the
No. 5 contractor has more of the nature of in-depth filtration than the No. 3 con-
tractor.
c. Organic Removal
Table 3.2.3 shows average of TOC removal in the two months of experiment.
TOC in the effluent from the No. 1 contractor is 9.8 mg/C against 10.2mg/C in
the No. 3 contactor effluent. The difference was 0.4 mg/2, or 4%. In view of this,
it could be concluded that there is little need of filter for TOC removal at present.
Fig. 3.2.23 shows the relationship between C/Co and BV in the contractors
No. 1 and 2. Fig. 3.2.24 gives the ratio of TOC in the effluent from the No. 1 con-
tractor to that from the No. 3 contractor. Judging from Fig. 3.2.23, carbon appears
to be breaking, but this must be more precisely examined by future results. And at
least up to Bed Volume (BV) of 5,000, there is no visible change in the ratio of TOC
in the effluent from the No. 1 contractor to that from the No. 3 contractor.
319
-------
Table 3.2.3 TOC Removal
Contactor No.
Number of Data
Influent to the Pri-
mary Contactor and
its TOC (mg/C)
TOC of Effluent
(mg/C)
TOC Removal
1
2
20
Filter Effluent of
Secondary Effluent
14.1
9.8
30
4.6
67
3
4
20
Secondary Effluent
14.5
10.2
30
5.1
65
5
6
15
Effluent from Alum
Precipitation of
Secondary Effluent
15.0
8.7
42
4.6
69
* Contactor Nos. 1, 3 and 5 are the primary contactors, and 2,4 and 6 the secondary.
** To the influent to the primary contactor.
Fig. 3.2.23 BV ~ C/Co
0.8.
80.6^
H
o
id 0.4
O
0.2-
°o
0 D
n °
QQ D
Influent: Filter effluent of secondary effluent a
O: Effluent from the primary contactor (No. 1 contactor)
D: Effluent from the secondary contactor (No. 2 contactor)
1000
2000 3000
BV
4000
5000
Fig. 3.2.24 Comparison of TOC between No. 1 Contactor Effluent and
No. 3 Contactor Effluent
„ 1.2
o 1
0.9-
0.8
N = 22
Average = 1.04
_Q O_
Influent
No. 1 contactor: Filter effluent of secondary effluent
No. 3 contactor: Secondary effluent
1000
2000
3000
4000
5000
BV
320
-------
3.2.3 SUMMARY
Table 3.2.4 gives the summary of the removal of suspended solids by the filter
and the carbon contractor in terms of the SS removal ratio, the SS loading and the
treated volume under specific operating conditions.
Followings are the findings of this study:
Table 3.2.4 Summary
Filter
Carbon
Con-
tactor
Influent
Second-
ary
Effluent
Tertiary
Alum
Precipi-
tated
Effluent
Filtered
Second-
ary
Effluent
Second-
ary
Effluent
Tertiary
Alum
Precipi-
tated
Effluent
Filtra-
tion
Method
Constant
Varying
Constant
Varying
Constant
Varying
Constant
Varying
Constant
Varying
Filtra-
Rate
(m/day)
180
300
420
500
300
420
120
180
300
180
240
Suspended Solid Removal
Removal (%)
2.5
61
*
61
*
61
*
*
SSinlr
5
61
y = o.:
kfluent
7.5
61
87-x-
61 1 61
y = 0.387-x
61 I 61
y = 0.387-x
42 I 48
y = 0.381-x
42 48
*y = 0.381-x
*
62
*
62
*
62
62
#
—
-
58
49
62
62
42 48
y = 0.381-x
55 | 53
y = 0.521-x-
55 | 53
y = 0.521-x
(mg/fi)
10 20
1-0.02
1-0.02
1-0.02
52 57
H.01
52 57
H.01
52 57
H.01
52 50
-0.36
52 50
-0.36
55 1 53 52 50
y = 0.521-x-0.36
55 1 53 52 50
y = 0.521-x-0.36
- 1 -
-
58
« y =
49
» y =
62
62
-
58
0.417
49
0.515
62
0.381
62
0.381
-
•x
• x
62 62
•x
62 62
•x
SS Loading (g/m1 )
SSinI
2.5 5
- 1,700
nfluent
7.5
2,300
(mg/B)
10
-
20
- 1 3,000 1 3,500 1 -
1 3,000 1 3,500 1
|1,700|2,300|
-
—
|3,100|2,800|
- |2,100|2,800| -
490 650
y *
490 650
«« y =
490 650
*» y =
820
66-X +
820
66-x +
820
66-X +
490 650 820
** y = 66>x +
-
-
-
980 |l,600
320
980 |l,600
320
980 ll,600
320
980 |l,600
320
-
-
-
- - -
700 1 1, 200 1 1,700
-
-
2,000
"
-
Filtered Volume (m'/m1)
SS
2.5 5
560
1 980
|980
810
- 1980
- 1980
310 I 240
310 |240
310 |240
310 |240
-
-
n Influent
7.5 1
500 -
770
770 -
640
770
770
210 19
210 19
) 20
-
-
-
-
-
-
0 160
0 160
210 190 160
210 19
-
0 160
-
-
— — — — —
450 |390
-
370 32
-
0
-
* y: SS in Effluent (mg/B), x: SS in Influent
** y: SS Loading, x: SS in Influent
a. Varying and Constant Filtration
1) When the secondary effluent is used as influent for filter, the comparison be-
tween varying and constant filtration at the filtration flow rate of 300, 420 m/day
leads to the following conclusions: The effluent by varying filtration contain more
of suspended solids by about 1 mg/£ than that by constant filtration. The SS load-
ing by varying filtration becames lower by 20 ~ 30%. The lower efficiency of vary-
ing filtration is also observed as to the SS removal ratio in carbon contractors using
the secondary effluent as influent by 10% drop.
321
-------
2) When the effluent from alum precipitation is used as the influent for filter or
carbon contractor, there is little difference of the SS removal and the SS loading
between varying and constant filtration in this study. In carbon contractors, vary-
ing filtration is a little less efficient in terms of the SS loading.
3) As seen in varying filtration experiments in the filter using the secondary
effluent as influent, time when the total head loss reach to 3 m is limited to the
closing period of influent flow increasing or to the time of high influent flow.
About 50% of the runs it comes within one hour in the closing period of effluent
volume increase.
b. Filtration of the Secondary Effluent by Filter (Constant Filtration)
1) In the filter media composition used for this experiment, the optimum filtra-
tion flow rates in terms of the effluent quality, and the SS loading are 300 ~ 420 m/
day. This is understood by the fact that the head loss distribution in the filter bed
came very close to that of in-depth filtration.
2) When the rates are 300, 420 m/day, and SS in the influent is 5 mg/C, the SS
removal is 61% and the SS loading is 3,000 g/m2.
3) Filtration at the rate of 180 m/day seems to be the surface filtration. The rate,
when compared to the higher rates of 300, 420 m/day, provides no difference as far
as the SS removal ratio. But the SS loading of this rate is about 60% of that of 300,
420 m/day.
4) The removal of suspended solids by the anthracite layer cannot be expected
at the rate of 500 m/day. Most of the SS capture takes place in the sand layer. At
this rate the SS in the effluent is by about 1 mg/£ greater than at the rates of 300,
420 m/day. The SS loading is about 60% of the value for the rates of 300, 420 m/
day.
c. Filtration of Alum Precipitated Effluent by Filter (Constant Filtration)
1) In the rates of 120 ~ 300 m/day, there is no difference in the SS removal and
the SS loading. When the SS in the influent is 5 mg/8, the SS removal rate is 55%
and the SS loading 650 g/m2
2) The SS removal by anthracite could not be expected. Most of the SS capture
takes place in the sand layer. This means that the anthracite in this bed, having the
effective size of 1.62, is large for the treatment of the effluent from alum precipita-
tion.
d. Solid Removal by Carbon Contractor
1) When treated by the carbon contractors, the filter effluent of the secondary
effluent and the secondary effluent itself make no great difference in their effluent
quality. The quality difference is only 9% for suspended solids and 4% for TOC up
to BV 5,000.
2) When compared to filter filtration of the secondary effluent, there is no great
difference in the SS removal efficiency. The carbon contractor also is not inferior in
terms of the SS loading.
3) When the effluent from alum precipitation with SS of 5 mg/£ is used as
influent, the SS removal ratio is 55% and the SS loading is 1,200 g/m2 (the total
head loss-5 m). When the total head loss is 3 m, the SS loading will be 65% of the
322
-------
value at 5 m of the total head loss, or 780 g/m2.
4) When compared to filter filtration by using the effluent from alum precipita-
tion as influent, the carbon contractor is superior both in the SS removal ratio and
the SS loading.
e. Filtration of Alum Precipitated Effluent and Secondary Effluent
1) In the case of the filter filtration at the flow rates of 180, 300 m/day, the SS
removal and the SS loading is better in secondary effluent filtration. The SS loading
of the effluent from alum precipitation was about 30% of that of the secondary
effluent.
2) In the case of the carbon contactor, the SS removal rate of the effluent from
alum precipitation was better by 3% but its SS loading was smaller than that of the
secondary effluent.
f. Future Studies to be Conducted
1) Varying filtration experiments by changing the filtration rate gradient or by
changing the ratio of the maximum flow rate to the minimum flow rate.
2) Dual or multi media filtration of the effluent from alum precipitation by using
anthracite with the effective size smaller than 1.62 mm.
3) To compare constant and varying filtration by using the same filter to verify
the results above. The experiment is now in progress.
4) To examine the carbon contractor filtration including the aspect of carbon
regeneration. Up to now it is known that the treatment of sewage including sus-
pended solids by the carbon contractor produces no major problem with regard to
SS and TOC in the effluent. Also needed is to know the performance of the carbon
contractor in treating the influent of high SS. The average SS in the secondary
effluent used so far is low at 4.5 mg/C.
5) To check whether there is a drop in the absorption speed by using coarse
carbon, which have proved to be efficient for the removal of suspended solids.
323
-------
CHAPTER 4. EXPERIMENTAL STUDY ON REGENERATION OF
GRANULAR ACTIVATED CARBON
Introduction 325
4.1 Method in the Experiments 325
4.1.1 Granular Activated Carbon used for Experiments 325
4.1.2 Facilities used in Experiments 325
4.1.3 Items Measured 326
4.1.4 Regenerating Conditions 327
4.2 Results of Experiments 328
4.2.1 Recovery Rate with Regeneration 328
4.2.2 Physical Characteristics Change of Granular Activated Carbon 328
4.2.3 Change of General Characteristics 332
4.2.4 Adsorption Characteristics of Organic Matter in Water 335
4.2.5 Decline of Various Characteristics of Activated Carbon 335
4.2.6 Correlation between Each Characteristics of Activated Carbon 335
4.2.7 Parameter as a Base for Calculation of Regenerating Cost 338
4.2.8 Others 339
4.3 Summary 344
Acknowledgement 344
324
-------
4. EXPERIMENTAL STUDY ON REGENERATION OF GRANULAR
ACTIVATED CARBON
INTRODUCTION
In wastewater treatment, particularly in advanced wastewater treatment, it
increases such a case that granular activated carbon is used as a means of removal
of soluble organic substances.
The unit cost of granular activated carbon is extremely expensive because a
good quality of bituminous coal as its raw material is difficult to obtain in Japan
and the product yield from such raw material is very small. These are the principal
defect of granular activated carbon when we used it for wastewater treatment.
Consequently if spent carbon can simply be regenerated at the inexpensive cost, the
utilization of granular activated carbon to wastewater treatment will be increased.
The regeneration of granular activated carbon is normally carried out by the
manufacturers, but in the case of wastewater treatment which requires activated
carbon is quantity equivalent to approximate 1/50 and (approximate 1/100 by
weight) more of wastewater to be treated per day, more regeneration on site is
required as the scale of wastewater treatment becomes larger.
The following are the results of our experiments we have conducted four items
on the activated carbon used in advanced wastewater treatment of the Kyoto pilot
plant by a multiple hearth regeneration furnace.
4.1 METHOD IN THE EXPERIMENTS
4.1.1 GRANULAR ACTIVATED CARBON USED FOR EXPERIMENTS
The brands and particle sizes of activated carbon used for our experiments are
shown in the Table 4.1 and these types of activated carbon have been used for the
adsorption of rapidly filtered secondary effluent in the Kyoto pilot plant. In our
adsorption experiments, no fresh carbon has been added since we intended to
observe the changing characteristics of the original carbon with repeat of regener-
ation. The approximate figures of adsorbed of COD^n obtained from the result of
adsorption experiment is also shown in Table 4.1. The CODMn removal in treatment
just before regeneration was approximately 30% in each case.
4.1.2 FACILITIES USED IN EXPERIMENTS
The facilities used for our experiments comprised a regeneration furnace, an
equipment for feeding and collecting carbon, an equipment for treating exhaust gas
and a steam generator. A general flow is as shown in Fig. 4.1. The regeneration
furnace is a vertical type six stage hearth furnace having the inside diameter of
750 mm and 1,500 mm of the height which is equipped with eight gas burners. The
arms of the furnace can be rotated within the range of 0.23 to 2.3 rpm by a 0.4 kW
driving motor.
325
-------
Table 4.1 Carbon Used in Experiment and Adsorbed CODMn
Number of Reactor
1
2
3
4
5
6
Name and Size
Name
Particle Size (Mesh)
Calgon, SGL
8x30
Calgon, CAL
12x40
Takeda, Shirasagi
8x30
Adsorbed CODMn (CODMn kg/kg A.C.)
1st
2nd
3rd
4th
Mean
0.118
0.150
0.132
0.165
0.141
0.074
0.067
0.047
0.067
0.064
0.160
0.170
0.160
0.202
0.189
0.088
0.080
0.061
0.079
0.077
0.121
0.155
0.086
0.125
0.122
0.085
0.057
0.048
0.072
0.066
Fig. 4.1 Flow Diagram of the Regeneration System
ED
r
x-k
/s A,
P-i
SC-I
RF-I
OP-I
| Uasmcier[
1
Fuel gas
K
3
1
Screw conveyer
Regeneration furna
Oil pump
£3gt_i
— ~t
E
ji . i
i^U-
^ £D
J
r
— J- 1
EL
_rt
? ,
fRn
• — i i
i
1 '
LilJ
'^
A- 1 txhaust gas furnace
D-l Scrubber
e S-l C'huTiney
B-l Boiler
I
rrr
/^
r-
I-
[HD
Waler
V
^ f
^^
r
A
[ED
^
1 W
rm * IQO t
3
n
1
J '
N
B'R
-I
!--€(
|TF
42
EH)
En
]
T-l Quench tank C'P-I Recycle pump
1
-2 Seal tank
T-3 Dewatenng tank
F-l Exhaust gas fan
4.1.3 ITEMS MEASURED
The items indicating the characteristics of granular activated carbon that meas-
ured in this experiment are; physical characteristics (mean particle size, hardness
number, ignition residue, specific surface area, mean micropore size, volume of
micropore, micropore distribution), general adsorption characteristics (methylen
blue decolorizing capacity, iodine adsorption capacity, molasses decolorizing capaci-
ty, phenole value, ABS value), adsorption capacity of organic substances in water
and weight ratio of adsorbed matter to fresh carbon.* Measuring has been imple-
*: Weight ratio of adsorbed matter to fresh carbon can be obtained by the following; a 100 kg of dried sample
of spent carbon will be heated for 90 minuts in an electrical furnace, the temperature of which was controll-
ed to 900°C in N2 gas flow, and the decreasing of weight are measured, then the weight ratio will be obtained
according to the following formula;
Weight Ratio of Adsorbed Matter to Fresh Carbon = Pleased Weight of Carbon (g)
Weight of Recovered Carbon (g)
326
-------
mented in accordance with JIS standards and Japan Water Works Association
(AWWA) Standards as far as practicable, but the details of the method have been
omitted because it was described in the previous report.
4.1.4 REGENERATING CONDITIONS
Regenerating efficiency of granular activated carbon in the regeneration fur-
nace will be governed by the following factors;
(1) Temperature and its distribution in furnace
(2) Detention time of activated carbon in furnace
(3) Atmosphere in furnace
(4) Feed rate of steam for reactivation and its feeding position
(5) Loading rate of carbon
In our experiments, the furnace temperature has been kept in 930 to 940° C at
a maximum. Each stage of 4th, 5th and 6th hearth for activating has been so set as
to be able to maintain nearly the same temperature. The detention time of activated
carbon in the furnace has been set for 30 min. regardless of the type and loading
quantity of carbon. Atmosphere in the furnace has been so controlled that O2 for
each stage should be kept below 0.1% to avoid the burning-off of carbon due to the
entrance of air.
The activating temperature has been changed based on the type of activated
carbon and apparent density which show the result for any change of loading quanti-
ty and can be measured easily. One third of the steam has been fed to the stage 4
and the remainder to the stage 6.
The loading rate of activated carbon has been set at from 11 to 15 kg/m2 of
furnace floor/hr on the basis of dry spent carbon by weight.
Total feeding weight or volume and loading quantity/hr in the regeneration
experiments carried out four times are as shown in Table 4.2. The activated carbon
Table 4.2 Feeding Weight and Feeding Rate of Each Carbon in the Experiment
\~ — -_____Reactor
It \xRegeneratiorf^\
Items ^---5_L_ \^
Weight of
Feeded
Activated
Carbon
(DSC kg)
Weight of
Feeded
Activated
Carbon
per Hour
(kg DSC/Hr)
1st
2nd
3rd
4th
Mean
1st
2nd
3rd
4th
Mean
1
836.0
784.9
670.9
618.5
727.6
39.5
34.2
33.5
34.4
35.4
2
836.0
752.3
601.9
546.5
684.2
34.3
32.4
31.7
33.0
32.9
3
696.7
681.5
577.6
596.2
563.0
33.6
36.9
28.1
32.5
32.8
4
727.5
645.6
567.7
550.5
622.8
32.1
31.0
28.8
30.2
30.5
5
809.0
798.0
735.8
733.3
769.0
35.6
38.2
35.0
36.1
36.2
6
835.9
791.7
693.3
686.3
751.8
34.0
36.8
32.8
33.9
34.4
327
-------
withdrawn from the reactor has been put into the hemp sack and dewatered when
the specific gravity was stabilized in wet condition. The activated carbon has been
loaded by weighing each sack of carbon.
In adsorption experiments at the pilot plant, each of the carbon was divided
and packed into two vessels. And the vessels were operated in series. So, this
regeneration experiment has been implemented by two vessels in a similar manner.
The first experiment has been carried out in December, 1974, the second experi-
ment in August, 1975, the third experiment in February, 1976 and the fourth
experiment in August, 1976 respectively.
4.2 RESULTS OF EXPERIMENTS
4.2.1 RECOVERY RATE WITH REGENERATION
The recovery rate of activated carbon with regeneration can be expressed both
gravimetrically and volumetrically. It is generally said that the reliability of the
former is greater than that of the latter although the former has problems that we
cannot grasp any change of particle size arising from mechanical and thermal losses
and that we cannot distinguish the influence of accumulation of inorganic sub-
stances.
Gravimetric recovery rate (Rw) can be obtained from dry weight of spent
carbon (Ws), weight ratio of adsorbed matter to fresh carbon (a) and dry weight of
regenerated carbon (Wr).
Ws
The volumetric recovery rate can further be obtained 1 ) from the height of
packed carbon and cross sectional area of the reactor and 2) from volumetric figures
calculated by dividing carbon weight with apparent density.
Each recovery rate obtained from this experiment is as indicated in Table 4. 3.
Each recovery rate varies by the type of carbon and by the frequency of use, but
was approximately 85% and above.
The fluctuation of height of packed carbon in reactor and apparent density
(measured by a 100 m£ measuring cylinder) with repeat of regeneration is as shown
in Fig. 4.2. In Fig. 4.2 and other diagrams, F, S and R on horizontal axis denote
fresh carbon, spent carbon and regenerated carbon, respectively. The numbers
show the frequency of adsorption and regeneration. From Fig. 4.2, it is noted that
apparent density relatively reduces as the carbon is regenerated repeatedly and that
the height of packed carbon lowers linearly. In accordance with that, carbon weight
of each reactor is reduced to approximate 50% of the original carbon weight only by
four times regeneration although it include a loss in back washing.
4.2.2 PHYSICAL CHARACTERISTICS CHANGE OF GRANULAR
ACTIVATED CARBON
Out of physical characteristics of the activated carbon. Fig. 4.3 shows the
change occurring from the repeated regeneration on mean particle size, hardness,
ignition residue, specific surface area and mean micropore size of micropore 0 to
300A. From these figures, it can be seen that by the repeat of regeneration, mean
particle size and hardness have not been changed very much, but ignition residue,
328
-------
Table 4.3 Recovery Rates in Regeneration Test (%}
^\~ — _____Reactor
^xRegeneratiorfX.
Items ^— ^ — \
Gravi-
metric
Recovery
Rate
Volu-
metric
Recovery
Rate
1
Volu-
metric
Recovery
Rate
2
1st
2nd
3rd
4th
Mean
1st
2nd
3rd
4th
Mean
1st
2nd
3rd
4th
Mean
1
96.2
91.9
94.7
90.8
93.4
95.6
88.0
90.2
83.8
89.4
99.3
92.7
100.6
93.0
96.4
2
94.0
96.8
93.0
91.9
93.9
94.1
89.6
84.7
80.0
87.1
96.1
94.0
95.7
95.9
95.4
3
102.3
95.1
98.5
99.8
98.9
97.4
90.0
83.2
86.1
89.2
107.7
96.7
105.2
103.0
103.2
4
98.1
105.1
89.7
94.1
96.8
94.1
91.1
86.3
87.1
89.7
98.2
100.0
90.0
94.5
95.7
5
100.2
99.6
87.7
89.6
94.3
95.8
93.4
84.8
87.4
90.4
99.8
98.5
90.8
92.2
95.3
6
97.0
93.8
98.7
95.1
96.2
96.1
91.8
93.4
90.6
93.0
98.5
92.2
101.4
95.2
96.8
Fig. 4.2 Change of Thickness, Weight and Apparent Density of Carbons with Repeat
of Regeneration
100 -
Note: The numbers in circle show column number ol carbon reactor
F IS 1R 2S 2R 3S 3R 4S 4R F IS IR 2S 2R 3S 3R 4S 4R F IS 1R 2S 2R 3S 3R 4S 4R
329
-------
Fig. 4.3 Physical Characteristic Change of Granular Activated Carbons with Repeat
of Regeneration
1.0 -
>- SGL, 8 x 30
I I
CAL, 12 x40
Shirasagi, 8x30
I I I
F IS 1R 2S 2R 3S 3R 4S 4R
(a) Mean particle size
7.0 -
%
6.0 -
5.0 -
F IS 1R 2S
(c) Ignition residue
2R 3S 3R 4S 4R
20
F IS 1R 2S 2R 3S 3R 4S 4R
(e) Mean pore size of 0~300A
90-
80-
70-
F IS 1R 2S 2R 3S 3R 4S 4R
(b) Hardness value (Remaining rate in shieve)
1000-
m2/g
500-
F IS 1R 2S 2R 3S 3R 4S 4R
(d) Specific surface area
F IS 1R 2S 2R 3S 3R 4S 4R
(0 Converse of phenol value (x 100)
specific surface area, mean micropore size of micropore 0 to 300A have been
changed strikingly. Particularly specific surface area (Fig. 4.3 (d)) has been reduced
to nearly a 50% of the original area just after the regeneration at the time when the
carbon was spent. This explains well the mutual relationship between adsorption
status and regenerating efficiency. Further, ignition residue (Fig. 4.3 (c)) and mean
pore size of micropore 0 to 300A increased little by little with the repeat of re-
generation. The reduction of these values shows the progressing of the deteriora-
tion of the activated carbon considering the reduction of adsorption capacity
330
-------
as will be described later on. From the investigation of another physical character-
istics of micropore volume, the volume of each micropore size fraction varies with
the repeat of regeneration as shown in Fig. 4.4. The total volume of micropore
(Fig. 4.4 (a)) of the spent carbon showed a reduction of its value to 60 ~ 70% of
fresh carbon or regenerated carbon. The difference in the micropore volume from
300A to 15 AI (Fig. 4.4 (b)) between fresh carbon and spent carbon is relatively
small, but the volume increased gradually with repeat of regeneration. On the
contrary the micropore volume (Fig. 4.4 (f)) up to 12A varied considerably and the
Fig. 4.4 Micropore Characteristic Change of Granular Activated Carbons with Repeat
of Regeneration
0.50 -
cc/g
0.25 -
0.50
SGL,8 x30
I I I
CAL, 12 x40
I I I
Shirasagi, 8 x 30
I I I I
F IS IR 2S 2R 3S 3R 4S 4R
(a) Total volume of 0 ~ 15// micropore
F IS 1R 2S 2R 3S 3R 4S 4R
(b) Volume of 300A ~ 15/u micropore
0.080-
cc/g
0.060-
0.040-
f IS IR 2S 2R 3S 3R 4S 4R
(cj Volume of 0 — 300A micropore
F IS IR 2S 2R 3S 3R 4S 4R
fd) Volume of 30 ~- 60A micropore
¥ IS IR 2S 2R 3S 3R 4S 4R
fe) Volume of ]2 "~ 30A micropore
F IS IR 2S 2R 3S 3R 4S 4R
(f) Volume of 0~ 1 2A micropore
value reduced with repeat of regeneration. The difference in the value between
spent and regenerated carbon is greater on the volume of micropore size fraction,
but the value has not been noticeably increased nor decreased very much with repeat
of use and regeneration.
331
-------
From the above, we can consider that with repeat of use and regeneration, the
total volume of micropore has not been changed very much, but micropore volume
of 12A and less has been reduced and in its stead micropore from 300A to 15 ju has
been increased. This indicates a deterioration of activated carbon.
Furthermore, in regard to micropore, the distribution has been measured in
each regenerating experiment, but here as an example we have shown a change of
micropore distribution after the second and the fourth regeneration in comparison
with that of fresh carbon in Fig. 4.5.
From Fig. 4.5, it is noticeably that micropore reduced and micropore in-
creased.
4.2.3 CHANGE OF GENERAL CHARACTERISTICS
As an index of adsorption capacity of the activated carbon, methylene blue
decolorizing capacity, phenole value and ABS value are generally used. The change
of such an index with repeat of regeneration in this experiment is as shown in Fig.
4.6.
Generally speaking each item has been much changed with repeat of regenera-
tion and the value of spent carbon, fresh carbon, and regenerated carbon varied
widely in each case.
The following is the study on the characteristics of each index;
Methylene Blue Decolorizing Capacity (Fig. 4.6 (a))
The fluctuation of the capacity has sometimes been reduced to 40 to 50% and
was gradually reduced with repeat of regeneration. This index is proportionate to
the specific surface area of micropore of 15A and more, and is so much alike the
fluctuation of the specific surface area in (Fig. 4.4 (d)) or micropore volume of 0 to
12A in (Fig. 4.5 (f)).
Iodine Adsorption Capacity (Fig. 4.6 (b))
The fluctuation of the capacity is such that the capacity of fresh carbon has
sometimes been reduced to 20 to 30%, but the value decreased with repeat of
regeneration as shown in Fig. 4.5 (f) and Fig. 4.6 (a). This index is proportionate
to the specific surface area of micropore of 10A and more.
Molasses Decolorizing Capacity (Fig. 4.6 (c))
The fluctuation of capacity is such that the capacity of fresh carbon has been
reduced to 25 to 50%, but the value shows a reverse trend of the above two items
and increases with repeat of regeneration.
It is generally said that this index is proportionate to the specific surface area
ot micropore of 28A and more, but judging from the trend on the diagram, the
index is rather alike the change of micropore volume from 300A to 15 p. as shown in
Fig. 4.4 (b).
Phenole Value (Fig. 4.6 (d))
This index indicates the required amount of activated carbon to adsorb the unit
amount of phenole. Consequently, the smaller this value, the greater the adsorption
capacity. From Fig. 4.6 (d), the fluctuation of the value is greater, but even if the
capacity considerably reduces by the spending, the original capacity can be restored
by regeneration. The capacity will not be dropped much even after the repeated
regeneration.
332
-------
Fig. 4.5 Micropore Distribution Change of Granular Activated Carbons with Repeat
of Regeneration
„ 1.0
I 0.6
•5
\
§• 0.8
E
2nd Regenerated carbon
4th Regenerated carbon
Diameter of micropore D (A)
(b) CAL 12 x40
Fresh carbon
I
2nd Regenerated carbon
4th Regenerated carbon
logD
lo4
Diameter of micropore D (A)
(c) Shirasagi 8 x 30
— Fresh carbon
i
— 2nd Regenerated carbon
— 4th Regenerated carbon
Ju
T
logD
Diameter of micropore D (A)
333
-------
Fig. 4.6 Adsorption Characteristic Change of Granular Activated Carbons with
Repeat of Regeneration
0.5 H
» SGL,8x30
CAL, 12x40
0 Shirasagi, 8 x 30
I I I I
F IS 1R 2S 2R 3S 3R 4S 4R
(a) Methylen blue decolorizing capacity
F IS 1R 2S 2R 3S 3R 4S 4R
(b) Iodine adsorption capacity
100 -I
50 H
100 -\
50 -J
F IS 1R 2S 2R 3S 3R 4S 4R
(c) Molasses decolorizing capacity
F IS 1R 2S 2R 3S 3R 4S 4R
(d) Phenole value
200 -\
;00 -\
300 H
200 H
100 H
F IS 1R 2S 2R 3S 3R 4S 4R
(e) ABS value
F IS 1R 2S 2R 3S 3R 4S 4R
(0 Converse of ABS value (x 100)
ABS Value (Fig. 4.6 (e))
This value is an index for the amount of activated carbon required for the
removal of the required ABS as in the case of phenole value. The fluctuating status
is therefore much alike that shown in Fig. 4.6 (d). As it was difficult to compare it
directly with physical characteristics, we took the converses in consideration of the
meaning of the index and obtained the result as shown in Fig. 4.6 (f). From this dia-
gram, it is found that the converses of ABS value fluctuates quite alike specific
surface area, micropore volume of 12A and more, methylene blue decolorizing
capacity and iodine adsorption capacity
334
-------
4.2.4 ADSORPTION CHARACTERISTICS OF ORGANIC MATTER IN WATER
The major objective of wastewater treatment by activated carbon is to remove
organic matter in the wastewater. In order to study the organic substances adsorp-
tion characteristics of activated carbon which is used for advanced wastewater treat-
ment, it is considered important to measure the adsorption capacity of the carbon
for same kind of organic substances as contained in wastewater. In this experiment,
therefore, an experiment on isothermal adsorption has been carried out with TOC as
an index for organic matter by using secondary effluent sampled from a pilot plant.
We have consolidated the data according to Freundrich equation which was
obtained from the experiments, but due to insufficient data for each experiment and
unstable property of secondary effluent taken for sample, we could not grasp a clear
change of adsorption characteristics for organic substances with repeate of regener-
ation.
In order to analyze the adsorption characteristics of activated carbon against
organic substances in wastewater, it is difficult to use the Freundrich equation
because the concentration of the substances contained in secondary effluent is very
low and varied. It is therefore felt necessary first to identify and measure the
organic substances in secondary effluent to be treated and secondly to pick up some
predominant organic substances and finally to study the adsorption characteristics
with those pure substances.
4.2.5 DECLINE OF VARIOUS CHARACTERISTICS OF ACTIVATED
CARBON
Various characteristics of activated carbon change little by little with repeat of
use and regeneration, but will not be improved to the level of fresh carbon by re-
generation. This is clearly understood from Fig. 4.3 and Fig. 4.6.
Now on the assumption that some value of characteristics will be increased A
fold by every regeneration, the value of characteristics after regeneration n times,
which is expressed in Pn, will be;
Pn = Po • An Log Pn = n log A + log Po
where Po = Characteristics Value of Fresh Carbon
Here from the various characteristics values of fresh, spent and regenerated
carbon obtained from the four times regeneration, we have gotten the values of A
and Po by a minimum involution on the items which are likely to fit to the above
equation and have gotten the result as shown in Table 4.4 (a). In the Table, r is a
coefficient of correlation expressed in logarithms. Table 4.4 (b) indicates all C
values taken from Table 4.4 (a). The degree of decline depend on the type of
carbon. The degree of decline of various characteristics are lower than that of
gravimetric recovery rate.
4.2.6 CORRELATION BETWEEN EACH CHARACTERISTIC OF
ACTIVATED CARBON
As mentioned earlier in 4.2.3, there exists a greater correlation between physi-
cal characteristics and general adsorption capacity of activated carbons. For
instance, specific surface area in Fig. 4.3 (d) and methylene blue decolorizing capa-
city in Fig. 4.6 (a) shows nearly the same fluctuation. We have then studied about
correlation between various physical characteristics and general adsorption capacity
335
-------
Table 4.4 (a) Coefficients which show the Characteristic Change with Repeat of Regeneration
log Pn = n-log A + logP0 A =
= 10a, P0= TOb,C = (
100
^
^^^^^ Reactor
Iteni\ Symbol
Specific Surface
Area m2/g
Mean Pore Size of
0-300A Micropore
Volume of Micropore
0-1 SM cc/g
300A~15^ cc/g
0-300A cc/g
0-12A cc/g
Apparent Density
g/2
Mean Particle Size
mm
Methylene Blue
Decolorizing
Capacity mC/g
Iodine Adsorption
Capacity g/g
Molasses Decolor-
izing Capacity ''',
ABS Value
Converse of ABS
Value
Dry Weight of
Carbon kg
1 ~ 2
a
0.0295
0.0195
O.OI021
0.0367'
-0.01037
-0.04101
-0.0077
-0.02456
-0.0228
-0.0175
0.0114
0.0340
-0.03391
-0.07 106
b
2 980
1.321
0.0976
-0.5209
-0.3008
-0.6971
2.686
0.2154
2.237
-0.02632
1.797
1.6352
0.3642
2.9811
r
0.9221
0.9637
0.6129
0.9347
0.6126
0.9421
0.9318
0.9161
0.9076
0.9582
0.7418
0.8170
0.8169
0.9915
A
0.9343
1.0459
1.0238
1.0882
0.9764
0.9098
0.9824
0.9450
0.9489
0.9605
1.0266
1.0814
0.9248
0.8491
Po
955.0
20.94
0.7987
0.3014
0.5003
0.2008
485.3
1.642
172.6
0.9412
62.69
43.17
2.313
957.4
C
^6.57
4.59
2.38
8.82
A2.36
A9.02
Al.76
AS. 50
*5. 14
A3.95
2.66
8.14
A7.52
A15.09
3 ~4
a
-0.0299
0.0204
0.01332
0.0427'
-0.0105s
-0.0426s
-0.0067
0.0082
-0.0385
-0.0232"
0.0090
0.0317
0.03176
-0.0682s
b
3.004
1.335
-0.0625
-0.4962
-0.2615
-0.7035
2.655
0.0041"
2.314
-0.0005"
1.825
1.594
0.4051
2.9519
r
0.8789
0.9680
0.6578
0.9784
0.5143
0.9501
0.9002
0.4499
0.9762
0.9958
0.7945
0.9061
0.9072
0.9791
A
0.9335
1.0481
1.0311
1.1035
0.9759
0.9065
0.9847
1.0191
0.9152
0.9479
1.0210
1.0757
0.9295
0.8547
Po
1009.3
21.63
0.8660
0.3191
0.5476
0.1979
451.6
1.0096
206.1
0.9988
66.90
39.26
2.541
895.2
C
A6.65
4.81
3.11
10.35
A2.41
A9.35
'4.53
1.91
A8.48
a5. 21
2.10
7.57
A7.05
A14.53
5-6
a
-0.0168
0.0207
0.0195"
0.0423
0.0034"
-0.04376
-0.0110
-0.00332
-0.0188
-0.0158'
0.0137
0.0193
-0.0162
-0.0499"
b
2.959
1.317
-0.1146
-0.5303
-0.3257
-0.6777
2.694
0.2020
2.248
-0.0275
1.803
1.6452
0.3514
2.9723
r
0.6769
0.9960
0.8742
0.9799
0.1987
0.9189
0.9787
0.2225
0.8497
0.9714
0.8745
0.9396
0.8728
0.9922
A
0.9621
1.0488
1.0460
1.1023
1.0080
0.9041
0.9750
0.9924
0.9576
0.9643
1.0320
1.0454
0.9634
0.8914
Po
909.9
20.75
0.7681
0.2949
0.4724
0.2100
494.3
1.592
177.0
0.9386
63.62
44.18
2.246
938.2
C
A3. 79
4.88
4.60
10.23
0.80
A9.59
A2.50
A0.76
A4.24
A3.57
3.20
4.54
A3.66
AlO.86
n = time number of regeneration,
Pn = Value showing characteristic of the activated carbon after n th regeneration
Po = Value showing characteristic of the fresh carbon
A = sign of minus
r = Coefficient of correlation
-------
Table 4.4 (b) Decline of Granular Activated Carbon Characteristics
with Repeat of Regeneration
Items
Name of Carbon
^^
Specific Surface Area
Mean Pore Size of
0-300A Micropore
Volume of Micropore
0~15ju
300A-15M
0-300A
0-12A
Apparent Density
Mean
Particle Size
Methylene Blue Decol-
orizing Capacity
Iodine Adsorption
Capacity
Molasses Decolorizing
Capacity
ABS Value
Converse of ABS
Value
Dry Weighs of Packed
Carbon
SGL, 8x30
0.9343
1.0459
1.0238
1.0882
0.9764
0.9098
0.9824
0.9450
0.9489
0.9605
1.0266
1.0814
0.9248
0.8491
6.57
-4.59
-2.38
-8.82
2.36
9.02
1.76
5.50
5.14
3.95
-2.66
-8.14
7.52
15.09
CAL, 12x40
0.9335
1.0481
1.0311
1.1035
0.9759
0.9065
0.9847
1.0191
0.9152
0.9479
1.0210
1.0757
0.9295
0.8547
6.65
-4.81
-3.11
-10.35
2.41
9.35
1.53
-1.91
8.48
5.21
-2.10
-7.57
7.05
14.53
SHIRASAGI, 8 x 30
0.9621
1.0488
1.0460
1.1023
1.0080
0.9041
0.9750
0.9924
0.9576
0.9643
1.0320
1.0454
0.9634
0.8914
3.79
-4.88
-4.60
-10.23
-0.80
9.59
2.50
0.76
4.24
3.57
-3.20
-4.54
3.66
10.86
Note: Left number show recovery rate and right show declining rate (%). The numbers were
calculated statistically from result of experiments.
as well as correlation among adsorption capacities.
Assuming that item Y and item X is in the relationship as Y = AX + B, we have
obtained the values of A and B as well as coefficient of correlation R as shown in
Table 4.5 (a). Further in order to make it easier to understand, we have expressed
these values in matrix as shown in Table 4.5 (b). In Table 4.5 (a) and Table 4.5 (b),
coefficient of correlation marked with double circles are 0.95 and above, coefficient
of correlation marked with a single circle 0.85 to 0.95, coefficient of correlation
marked with a triangle 0.70 to 0.85.
From the Table 4.5 (b), relatively high correlation can be noticed as follows;
(1) Micropore volume from 0 to 300A vs. specific surface area and total micropore
volume.
(2) Micropore volume from 30 to 60A vs. total micropore volume from 0 to 15/u.
(3) Methylene blue decolorizing capacity vs. specific surface area, micropore
volume from 0 to 300A, micropore volume from 12 to 30A and micropore volume
from 0 to 12A.
(4) Iodine adsorption capacity vs. specific surface area, micropore volume from 0
to 12A and methyle blue decolorizing capacity.
337
-------
(5) Molasses decolorizing capacity vs. Micropore from 0 to 300A
(6) The converses of ABS value vs. specific surface area, micropore volume from 0
to 300A, micropore volume from 0 to 12A, methylene blue decolorizing capacity
and iodine adsorption capacity.
4.2.7 PARAMETER AS A BASE FOR CALCULATION OF REGENERATING
COST
The regeneration cost of activated carbon is a very expensive so, as the case
may be, it is advisable to purchase fresh carbon, but in case of regeneration, it must
be more in-expensive than purchasing fresh carbon if we can enhance recovery rate
by reducing the costs for fuel, for electricity and for labor since we require no raw
materials. Out of the three costs above, most important one is considered to be fuel
cost so we have prepared Table 4.6 covering unit values of all the relevant items of
fuel costs from the data obtained-from this experiment. The moisture of spent
carbon feeded into a regeneration furnace in this experiment was 40 to 50%, but
from Table 4.6, propane gas consumption for spent carbon with such water content
was 50 to 55 C/kg wet weight of feeded carbon, 87 to 99 £/kg dry weight of feeded
carbon while fuel oil consumption at after-burning room for treatment of exhaust
gas was 0.1 to 0.14 e/kg dry weight of feeded carbon. Further, the feeding rate of
Table 4.5 (a) Correlation between Each Characteristic of Granular Activated Carbon
Y = AX
+ B
™=:
A
©
O
O
O
O
©
A
O
O
O
O
A
A
O
O
O
©
©
©
— — ___
X
Specific Surface Area
m'/g
Specific Surface Area
m'/g
Specific Surface Area
m'/g
Specific Surface Area
m'/g
Specific Surface Area
m:/g
Volume of Total
,.!'cropure cc/g
Volume of Total
Micropore cc/g
Volume of 300A~15n
Micropore cc/g
Volume of 0-300A
Micropore cc/g
Volume of 0-.100A
Micropore cc/g
Volume of 0-300A
Micropore cc/g
Volume ol .12-30A
Micropore Lc/g
Volume ol I2~30'\
Micropore cc/g
Volume ol I2-30A
Micropore cc/g
Volume of 0-I2A
Micropore cc/g
Volume of l)~ 1 2A
Micropore cc/g
Volume of 0-1 2A
Mkropore cc/g
Mcthylene Blue Decol-
orizing Capacity mS/g
Methylene Blue Decol-
orizing Capacily mC/g
Iodine Adsorption
Capacily g/g
Carbon
Y
Volume of Total
Micropore cc/g
Volume of 0-300A
Micropore cc/g
Methylene Blue Decol-
orizing Capacity mC/g
Iodine Adsorption
Capacity g/g
Converse of ABS
Value (%)
Volume of 0-300A
Micropore cc/g
Volume of 30-60A
Micropore cc/g
Molassls Decolorizing
Capacity %
Melhylene Blue Decol-
orizing Capacity mC/g
Molassls Decolorizing
Capacity 7r
Converse of ABS
Value ('/„)
Methylene Blue Decol-
orizing Capacity mC/g
Iodine Adsorption
Capacily g/g
Molassls Decolorizing
Capacity %
Methylene Ulue Decol-
orizing Capacity m2/g
Iodine Adsorption
Capacity g/g
Converse of ABS
Value (%)
Iodine Adsorption
Capacity g/g
Converse of ABS
Value (%)
Converse ot ABS
Value (7)
A
0.0005746
0.0004762
0 1506
0.0004774
0.002861
0.6644
0.06289
121.6
293.2
88.57
5 633
832.8
2.677
216.2
680.6
2.175
12.75
0.002993
001916
6 103
SOL
B
0.3148
007339
27.60
0.4668
-0.4466
-0.08849
0.006752
17.85
13.67
23.05
-0.7365
28.03
0.4635
31.79
38.65
0.4995
-0.2121
0.4026
-0.9927
-3.331
R
0.8285
0.9676
0.9186
0.9484
0.9036
0.9364
0.9596
0.7013
0.8798
0.8794
0.8753
0.8576
0.8983
0.7368
0.9186
0.9565
0.8913
0.9754
0.9923
0.9699
A
0.0006005
0.0004919
0.1646
0.0004848
0.002842
0.6744
0.06782
150.6
301.5
95 00
5.496
835.5
2.488
219 1
788.0
2.336
13 36
0.002829
001644
5.644
CAL
B
0.3652
0.08239
27.13
0.4711
-0.3500
-0.1025
0.005039
7.446
13.77
20.76
-0.7054
26.08
0.4642
30.83
4256
05146
-005296
0.4078
-0.6996
-2.935
R
0.8487
0.9738
0.9200
0.9481
0.9328
0.9447
0.9317
0.7549
0.8510
08485
0.9114
0.8980
0.9358
0.7453
0.9250
0.9596
0.9218
0.9903
0.9657
0.9475
A
0.0005522
0.0004899
0.1634
0.0004969
0.003073
0.6470
0.07311
1686
289.5
110.1
5.679
921.2
2.649
3338
607.5
1.932
11.34
0.003059
0.01817
5.674
Shirasagi
B
0.3706
0.06442
22.99
0.4499
-0.5582
-0.08314
0.002073
2.293
19.37
14.80
-0.7214
21.93
0.4656
1784
54.05
0.5328
-0.03731
0.3775
-0.9035
-2.934
R
0.7608
0.9535
0.9272
0.9009
0.9448
0.9141
0.9771
0.7609
0.8439
0.8834
0.8971
0.8446
0.7762
0.8422
0.9224
0.9373
0.9331
0.9775
0.9845
0.9621
338
-------
Table 4.5 (b) Correlation between Each Characteristic of Granular Activated Carbon
\
Specific
Surface Area
Volume of Micropore
Total
Micropore
300A-15M
0-300A
30-60A
12-30A
0-12A
Methylene Blue
Decolorizing
Capacity
Iodine
Adsorption
Capacity
Molasses
Decolorizing
Capacity
m'/g
cc/g
cc/g
cc/g
cc/g
cc/g
cc/g
Converse of
ABS Value
90-95
O
-
87-92
0
-
-
89-94
0
96-100
94-97
-
so
ill
_ca O a
-
70-77
A
84-89
O
-
73-85
A
-
-
-
Iodine
Adsorption
Capacity
90-95
O
-
-
-
-
77-94
A
93-96
O
97-100
Methylene Blue
Decolorizing
Capacity
91-93
O
-
-
84-88
O
-
84-90
O
91-93
O
Volume of Micropore
fS
T
o
-
-
-
o
-
-
-
-
-
o
VO
1
O
-
93-98
-
-
0
o
m
O
95-98
91-95
O
-
10 "
— o
I a. a
76-85
A
-
Numbers in the frame show range of
correlation coefficient (x 100).
steam for reactivation of carbon was 0.7 to 1.0 kg/kg while air blow rate for gas
burning was approximate 21.1 liter per liter of propane gas.
Mean temperature distribution of atmosphere in furnace during regeneration is
as shown in Fig. 4.7 and the temperature was controlled satisfactorily.
The concentration of CO, CO2 and O2 for atmospheric gas in the lowest stage
which we analyzed is as shown in Table 4.7 and from this data, it is found that the
reductive atmosphere was obtained.
4.2.8 OTHERS
In this experiment, component of exhaust gas, concentration of odor sub-
stances, and the fluctuation of content of inorganic substances in activated carbon
before and after regeneration was measured.
Properties and Component of Exhaust Gas
Properties and component of exhaust gas from regenerating furnace itself,
after-burning room and scrubber in regeneration of activated carbon are as shown in
Table 4.8. From Table 4.8, it can be said that the dusts and odor strength are
removed by after-burning, but sulphurous acid gas and NOx rather increase.
Scrubber is effective to remove dusts and sulphurous acid gas, but did not contri-
buted to the removal of NOx. The increase of odor strength at scrubber was due to
the use of secondary effluent for scrubbing.
339
-------
Concentration of Odor Substances
In our second and third regeneration, the concentrations of odor substances
and dangerous substances contained in exhaust gas from regenerating furnace and
after-burning room were measured. The result is shown in Table 4.9. From Table
4.9, it can be said that the concentration of odor substances at the outlet of re-
generation furnace is considerably high, but after after-burning, such concentration
was considerably reduced. This explains the favorable impact of after-burning to
odor substances.
Fluctuation of Inorganic Substances Content with Repeat of Regeneration
Inorganic substances contained in carbon and fresh carbon before and after
regeneration were measured and the fluctuation of content with repeat of regener-
ation was studied. Items measured were altogether nine covering calcium, cadmium,
chromium, copper, mercury, magnesium, manganese, lead and zinc. The results of
this measurement are as shown in Table 4.10. With the exception of Ca, Cd, Mn,
Table 4.6 Basic Data on Fuel Cost
\x^~ -^-Jleactpr Number
\\ RegeneratiorT^^-^^
Item ^— ~ ^^^
Consumption Rate
of Propane Gas to
Wet Weight of Feeded
Spent Carbon
(E/kg WSC)
Consumption Rate
of Propane Gas to
Dry Weight of Feeded
Spent Carbon
(2/kg DSC)
Oil Consumption Rate
for After Burning to
Wet Weight of Feeded
Spent Carbon
(B/kgWSC)
Oil Consumption Rate
for After Burning to
Dry Weight of Feeded
Spent Carbon
(t/kgDSC)
Steam Feeding Rate
to Dry Weight of
l-eeded Spent Carbon
(kg/kg DSC)
Air Blowing Rate to
Propane Gas
1st
2nd
3rd
4th
Mean
1st
2nd
3rd
4th
Mean
1st
2nd
3rd
4th
Mean
1st
2nd
3rd
4th
Mean
1st
2nd
3rd
4th
Mean
1st
2nd
3rd
4th
Mean
1
48.3
57.8
49.7
55.5
52.8
80.0
95.2
89.0
96.3
90.1
0.0832
0.144
-
0.121
0.116
0.138
0.237
-
0.209
0.195
0.737
0.535
0.901
0.875
0.762
22.5
20.2
22.7
21.6
21.8
2
47.7
57.6
52.3
53.4
52.8
82.6
101.3
99.0
97.1
95.0
0.107
0.163
0.123
0.133
0.132
0.185
0.287
0.233
0.242
0.237
0.962
1.006
1.013
0.909
0.973
24.6
18.9
21.5
19.6
21.2
3
49.0
54.8
62.3
53.1
54.8
85.2
94.4
117.0
97.9
98.6
0.107
0.145
0.100
0.112
0.116
0.185
0.249
0.189
0.206
0.207
0.919
0.899
1.199
0.926
0.986
23.9
18.4
20.9
21.6
21.1
4
43.4
51.1
54.4
49.6
49.6
78.9
93.4
103.7
100.9
94.2
0.121
0.151
0.148
0.141
0.140
0.220
0.277
0.281
0.272
0.263
0.941
0.919
1.052
0.993
0.976
25.3
19.0
20.8
20.5
21.4
5
44.3
55.2
63.4
62.1
56.3
77.1
93.3
109.1
106.3
96.5
0.0967
0.121
0.0946
0.0971
0.102
0.168
0.204
0.163
0.166
0.175
0.870
0.819
0.826
0.801
0.829
25.1
18.1
20.4
21.0
21.2
6
43.4
55.6
5.1.8
50.7
50.4
75.9
93.9
92.7
93.5
89.0
0.116
0.161
0.120
0.120
0.129
0.202
0.216
0.230
0.221
0.217
0.864
0.823
0.951
0.867
0.876
25.0
17.2
21.7
22.3
21.6
340
-------
Fig. 4.7 Distribution of Temperature in Furnace
1000
2nd Regeneration (Aug. 1975)
1st Regeneration (Dec. 1974)
T.F 2nd 3rd 4th 5th
hearth
3rd Regeneration (Feb. 1976)
4th Regeneration (Aug. 1976)
Carbon of
Column 1
Carbon of
Column 1
Carbon of
Column 3
Carbon of
Column 4
Carbon of
Column 6
Carbon of
Column 5
T.F 2nd 3rd 4th 5th 6th
200
341
-------
Table 4.7 Contents of Atmosphere Gas (%)
^^^^^ Item
^^^^_^
Times of Regeneration ~^^_^
1
2
3
4
CO
2.0-3.4
1.9-3.4
1.7-1.9
1.7-1.9
CO2
12.0-12.2
11.9-12.9
11.0-11.8
11.1-11.6
02
0.1 or less
0
0
0
Table 4.8 Exhaust Gas Component
Items
Gas Temperature °C
Dry Gas Volume Nm3/H
Moisture V/V %
Dust g/Nm3
Method of Analysis
JIS Z8808
JIS Z8808
JIS Z8808
Dust Tube Method
Qn „„ '• JIS K0103 Solution
SUj PP • Conductivity Method
Mri _ : JISK0104 Chemical
N0 ppm Radiation Method
NOx ppm ' JIS KOI 04
Power of Odor (PO) £u™n™ Method
CO2 V/V % Orsat Method
02 V/V % Orsat Method
CO V/V %
Orsat Method
Outlet of Re-
generation Furnace
1st
240
69
42.4
1.31
3
62
-74
65
-76
11.9
10.9
3.3
-
2nd
240
83
42.8
3.14
<5
66
-70
66
-70
11.9
10.4
3.3
3.3
3rd
266
88
39.4
3.84
<5
-
40
-60
10.4
9.6
0.9
2.9
Outlet of After
Burning Room
1st
620
675
22.5
0.16
235
-240
100
-110
105
-115
2.6
11.4
4.0
-
2nd
650
272
21.6
0.27
140
-170
85
-89
88
-94
1.0
7.6
9.3
0
3rd
643
185
35.9
0.26
350
-400
-
125
-135
0
10.2
6.1
0
Outlet of
Scrubber
1st
40
373
2.4
0.05
6-9
113
-123
118
-128
5.3
8.3
8.6
-
2nd
50
294
12.2*
0.05
<5
107
-111
107
-115
2.3
5.8
12.4
0
3rd
25
229
13.1
0.06
<5
-
125
-130
5.1
9.9
6.2
0.2
and Pb, the content of each substance was greater in spent carbon than regenerated
carbon and also normally greater in primary reactor than in secondary reactor.
This explains that activated carbon has adsorbed metals to some extent and has
accumulated part of metals without taking off it in regeneration. A high concentra-
tion of Ca was due to the impact from the regeneration of lime in the regenerating
reactor.
342
-------
Table 4.9 Concentration of Odor and Dangerous Substances in Exhaust Gas (ppm)
Items
Name
Hyarogen
Cyanide
Carbon
Disulfide
Acetic Acid
Formaldehyde
Acetaldehyde
Methane
Ethane
Ammonia
Tri-methyl
Amine
Hydrogen
Sulfide
Methyl
Mercaptan
Dimethyl
Sulfide
Chemical
Formula
HCN
CS2
CH3COOH
HCHO
CH3 -CHO
CH4
C2H6
NH3
(CH3)3-N
H2S
CH3-SH
(CH3)2-S
Measuring Method
JIS K0109 Pyridine
Pyrazolon Method
E.A. Notification No.9
FPD-GC Method
FID -GC Method
JIS K0102 Acetyleace-
tone Method
FID -GC Method
FID -GC Method
FID-GC Method
JISK0099 Indo
Phenol Test
E.A. Notification No.9
E.A. Notification No.9
E.A. Notification No.9
E.A. Notification No.9
Threshold
Value
1.0
0.21
0.0021
0.005
0.041
Outlet of
Furnace
2nd
4.2
120
280
<0.7
<30
1100
54
990
<0.05
<3
<1
<0.5
3rd
5.2
90
370
0.19
19
1.360
3.5
680
<0.08
780
<2
<0.1
Outlet of After
Burning Room
2nd
<0.08
<0.1
40
<0.5
<30
<10
<10
0.49
<0.05
<0.03
0.002
<0.001
3rd
<0.006
<0.02
<0.2
<0.01
<0.3
35
<0.3
0.25
<0.008
0.15
<0.05
<0.03
Table 4.10 Change of Inorganic Matter Contents with Repeat of Regeneration
Unit: ppm
Car-
bon
S
G
L
C
A
L
S
H
I
R
A
S
A
G
I
^^^^Reactor
Status^\~
of Carbon ^\^
F
IS
1R
2S
2R
3S
3R
4S
4R
F
IS
1R
2S
2R
3S
3R
43
4R
I-
IS
1R
2S
2R
3S
3R
4S
4R
Primary Secondary
Ca
40
825
650
645
1575
1260
1800
2100
59
775
725
755
2115
1880
2560
2240
36
850
655
605
2125
1125
2505
2225
Cd
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
Cr
<0.5
-
12
25
10
12.1
6.7
25
15
<0.5
24
40
24
14.6
12.1
28
17
<05
-
12
29
10
11.5
4.8
11
1 1
Cu
0.5
16.5
41.0
31.0
45.7
25.7
49
39
1.5
-
37.5
55.0
34.0
61.7
49.1
70
44
0.5
23
49
22
88.5
17.7
64
37
Hg
(0.1)
0.02
1.47
0.05
0.10
<0.01
0.02
<0.01
(0.11)
0.03
1.50
0.03
0.06
0.01
0.10
<0.01
(009)
0.02
0.92
0.02
0.20
<0.01
0.10
<0.01
Mg
69
131
134
118
194
148
260
244
48
141
139
129
270
244
385
328
67
135
131
119
219
135
309
269
Mn
3
-
82
54.5
62
52.3
87.4
82
105
5
195
73
99
88.4
156.5
140
156
2.5
86
76
72
124.5
105.4
157
192
Pb
<5
<5
<5
<5
<5
<5
<5
<5
5
<5
10
<5
<5
<5
<5
<5
<5
<5
<5
<5
<5
<5
<5
<5
Zn
7
20.5
120
8.5
132
7.5
223
18
2
21.0
137
13.5
156
9.0
284
24
4.5
10.5
126
9
122
7.0
247
26
Ca
40
335
278
855
995
915
1270
59
370
330
1260
950
1235
1200
36
388
273
790
750
1215
1200
Cd
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
Cr
<0.5
28
8
9.7
7.3
15
11
<0.5
37
11
12.8
9.1
22
13
<0.5
25
7
11.5
6.1
13
8
Cu
0.5
_
43.0
19.5
37.1
20.0
31
16
1.5
395
14.5
42.8
14 3
34
14
0.5
31.5
10.5
20.7
8.6
30
7
Hg
(0.1)
0.28
0.04
0.13
<0.01
0.04
<0.01
(0.11)
0.15
0.04
0.10
<0.01
0.05
-------
4.3 SUMMARY
Repeat of regeneration experiments have been conducted on three types of
activated carbon being used for an advanced wastewater treatment at Kyoto pilot
plant and the following have been confirmed;
(1) Recovery rate was 90 to 100% gravimetrically but 85 to 95% volumetrically.
(2) Through the repeated regeneration, apparent density and micropore volume
was decreased, but mean particle size of micropore from 0 to 300A and micropore
volume from 300A to 15^ was increased. The rest of the items have not been
changed so much.
(3) Out of general adsorption capacity, methylene blue decolorizing capacity and
iodine adsorption capacity were decreased through the repeat of regeneration while
molasses decolorizing capacity was slightly increased. Phenole value and ABS value
were not fluctuated so much.
(4) It was found that the following items had extremely high correlation each
other;
Micropore volume from 0 to 300A vs. specific surface area, micropore volume
from 30 to 60A vs. total micropore volume from 0 to 15 M- Iodine adsorption
capacity vs. methylene blue decolorizing capacity, the converses of ABS values vs.
methylene blue decolorizing capacity and iodine adsorption capacity.
(5) Propane gas consumption by dry weight of feeding activated carbon was 87 to
99 C/kg. Fuel oil consumption for after-burning was 0.1 to 0.14 C/kg. Steam injec-
tion quantity for reactivation of carbon was 0.7 to 1.0 kg/kg.
(6) Due to after-burning, dust contained and odor strength of exhaust gas was
decreased, but SOx and NOx were increased. Scrubber was effective for the reduc-
tion of SOx, but not for NOx.
(7) Activated carbon adsorbes or removes metals in wastewater to some degree.
ACKNOWLEDGEMENT
The author thanks Mr. Yoneda and his stuff of sewage Works Bureau of Kyoto
City for their cooperation in the experimental study.
344
-------
UNITED STATES PAPERS
DEVELOPING PROGRAMS FOR CONTROL OF NONPOINT
(DIFFUSE) SOURCES OF WATER POLLUTION 347
R.S. Burd, Water Division, Region X, USEPA
HISTORY OF THE CONSTRUCTION GRANTS PROGRAM 351
T.P. O'Farrell, Office of Water Program Operations, OWHM, USEPA
UTILIZATION OF A FEDERAL ACT (PL 92-500) IN COORDINATION
WITH GEORGIA'S WATER QUALITY CONTROL PROGRAM 367
J.L. Ledbetter, Environmental Protection Division,
Georgia Department of Natural Resources
FEDERAL-STATE-REGIONAL DEVELOPMENT OF A WASTEWATER
MANAGEMENT PLAN AND A WATER SUPPLY PLAN 373
J.L. Ledbetter & H.F. Rebels, Environmental Protection
Division, Georgia Department of Natural Resources
REGIONAL SOLUTIONS TO DOMESTIC WASTEWATER MANAGEMENT 383
R.S. Burd, Water Division, Region X, USEPA
URBAN RUNOFF POLLUTION CONTROL TECHNOLOGY OVERVIEW 385
Dr. C.A. Brunner, R.I. Field, H.E. Masters, A.N. Tafuri,
Municipal Environmental Research Laboratory, ORD, USEPA
PLANNED WASTEWATER REUSE - A LITTLE USED RESOURCE 457
F.M. Middleton, Municipal Environmental Research
Laboratory, ORD, USEPA
INDUSTRIAL WASTEWATER PRETREATMENT AND JOINT
TREATMENT IN PUBLICALLY-OWNED TREATMENT WORKS 477
W.J. Lacy, Office of Research and Development, USEPA
CRITERIA AND ASSESSMENT OF WASTE TREATABILITY 501
Dr. R.L. Bunch, Municipal Environmental Research
Laboratory, ORD, USEPA
UPDATE OF BIOLOGICAL NITROGEN AND PHOSPHORUS CONTROL 519
Dr. R.L. Bunch, Municipal Environmental Research
Laboratory, ORD, USEPA
RESEARCH AND APPLICATION OF WATER RECLAMATION
TECHNOLOGY IN SOUTHERN CALIFORNIA 545
F.D. Dryden & M.W. Selna, Sanitation Districts of
Los Angeles County
345
-------
DEVELOPING PROGRAMS FOR CONTROL OF
NONPOINT (DIFFUSE) SOURCES OF WATER POLLUTION
R. S. Burd
U.S. Environmental Protection Agency, Region X
1200 Sixth Avenue
Seattle, Washington 98101 USA
ABSTRACT
Controlling nonpoint sources of pollution will be necessary in order to meet the
goals of the Federal Water Pollution Act. The paper describes the magnitude of the
pollution from these sources and describes a new approach being tried to solve the
problem. It primarily relies on State and local governments prescribing "best management
practices'1 and making important land use decisions. The program is highlighted by
active citizen participation and a shift from voluntary compliance to at. least a semi-
regulatory format.
INTRODUCTION
Non-point sources of water pollution,
such as runoff from croplands, urban
stormwater, and strip mining, are becoming
the single most important water quality
problems. To help solve this pollution
problem the U.S. Congress placed primary
responsibility on the States and local
units of government. The wastewater
management planning process being carried
out under Section 208 of the 1972 Federal
Water Pollution Control Act offers some
good possibilities to control this aspect
of water pollution.
BACKGROUND
In the U.S.A. current estimates
indicate that perhaps half our national
water pollution problem may come from
nonpoint (diffuse) sources of pollution.
These sources generally involve runoff,
usually after storms, from man-distrubed
land, streets, parking lots and other sur-
face areas. The seriousness of the pro-
blem is highlighted by the fact that it is
predicted the 1983 goals of the Federal
Water Pollution Control Act—i.e. all waters
being clean enough for fishing and swimming
—will not be met unless this source of
Pollution is brought under control.
Further highlights of the problems
associated with nonpoint source pollution
are: (1) Two billion tons of sediment are
delivered to lakes and streams annually
from over 400 million acres of croplands,
as well as large amounts of nitrogen from
fertilizers, phosphorus from nonpoint sources,
animal wastes from feedlots, and toxic
pesticides.
(2) Between 5 and 10 percent of the
total sedfment load is estimated to come
from the 10 to 12 million acres of Commer-
cial forest harvested each year.
(3) Strip mining, which affects about
350,000 acres annually, results in the dis-
charge of millions of tons of acidity and
sediment.
(4) Urban sprawl, which consumes
hundreds of square miles per year, generates
sediment at an even greater rate than agri-
cultural activities.
(5) The runoff of stormwater in urban
areas accounts for the pollution of waters
with large amounts of toxic and oxygen—de-
manding materials. It also contains large
amounts of suspended sediments and extreme-
ly high but variable coliform counts.
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As point sources of poTIution--sewage
and industrial wastes discharged through
pipes—are reduced, the nonpoint sources
gain in relative importance. There hasn't
been a systematic national program for mon-
itoring nonpoint source pollution and its
water quality impact-but-most everyone
agrees this pollution source is a major
problem.
NEW APPROACH
One new and important tool for control-
ling nonpoint source pollution is Section
208 of the Federal Act. It calls for State
and regional planning for water quality
management. Funds to do this planning are
provided by EPA. As in other areas, the
Federal Government is providing an incen-
tive and mechanism for local governments
to deal with a growing problem.
This planning for controlling nonpoint
sources of pollution encourages States and
local government agencies to prescribe so-
called best management practices (BPT). We
define BPT as a practice, or combination
of practices, that is determined by a State
or local governmental agency to be the most
effective and practicable means of prevent-
ing or reducing the amount of pollution
generated by nonpoint sources to a level
compatible with water quality goals. The
term practicable includes technological,
economic and political considerations. BPT's
are determined after assessment of the
problem, examination of alternative practi-
ces and appropriate public participation.
These practices may vary widely according
to local climate, topography, soils, geolo-
gy, vegetation and other conditions.
For the most part, best management
practices are known and many are in daily
use. But these techniques are not being
widely applied in many areas where serious
water quality degradation is occurring.
Studies have demonstrated that good
conservation practices can reduce sediment
yield anywhere from 50 to 90 percent. It
has been estimated that if soil conserva-
tion practices were applied to all farm
land, nearly 50 percent of the sediment
loading in streams would be eliminated, in
addition to a reduction in such related
pollutants as nutrients and pesticides.
Some typical best management practices
we hope will be adopted through the 208
planning process are as follows:
(1) Contour farming to reduce erosion
potential; (2) leaving buffer strips of
trees and shrubs along streams to reduce
soil erosion and to reduce temperature
increases from sunshine; (3) frequent street
sweeping during dry periods to prevent
storm water from carrying debris, oil and
other material into storm sewers; (4) sedi-
ment traps at new construction sites and at
shopping center locations to prevent silta-
tion of streams; (5) grass seeding or other
vegetation planting to stabilize areas of
construction activity; and (6) use of cul-
verts and other engineering structures to
control water flow and thereby reduce
erosion. There are many other examples of
practices which can be effective. New
techniques are continually being developed
which should be put to work. Most import-
ant is that each water quality management
agency define its own set of such practices,
tailored to meet specific local problems
and environmental conditions.
Prevention is the key to the control of
nonpoint source pollution. And, in this
regard, intelligent use of the land is most
important. Water quality is affected,
often very significantly, by land use deci-
sions. For part of the prevention answer
therefore we are expecting local governments
to use land zoning to reduce runoff by
precluding development in ground water
recharge areas, flood plains and ecologi-
cally sensitive areas. Public acquisition
of land for preservation areas is also
encouraged as is preferential tax treatment
to retain land for open space or agricul-
tual purposes.
IMPLEMENTATION
There already exist many Federal, State
and local programs that deal with some forms
of nonpoint source pollution. The Federal
Water Pollution Control Act, and particu-
larly Section 208, seeks to significantly
expand on and coordinate these programs.
Also, the Act suggests the programs be de-
veloped and carried out with the help of a
major public participation effort. This
has resulted in each State and local
government doing the nonpoint source control
planning to appoint advisory committees to
provide assistance.
The final result will be a workable
plan that identifies a governmental unit
best able to perform the necessary tasks.
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It will also often contain regulations and
ordinances controlling septic tank pollu-
tion; land used for development; and pre-
scribing best management practices for
agriculture, logging, and overall con-
struction activity. By putting these
measures into the form of regulations and
ordinances, a semi-regulatory (enforcement)
cast is given to the program. This is
probably necessary even though nonpoint
pollution will be prevented or eliminated
primarily through education and voluntary
compliance.
The program described will be continu-
ally evaluated for its effectiveness. If
an evaluation shows the goals aren't being
met additional measures, such as tougher
best management practices, will be adopted.
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THE NONPOINT SOURCES PROBLEM
SILVICULTURE
AGRICULTURE
Upppif Watershed
water sources
forest practices
grazing
HYDROLOGIC
MODIFICATION
(other sources mining, construction, ground water)
TYPICAL POLLUTANTS
1 Sediment 6 pestjcjdes
2 Nu'fi«n»s 7 Heavy Metals
3 Temperature „ Di$so|ved Sa|t$
4 Dissolved Gases O2 N2 on • u . • i
c _ . ' "•* 9 Organic Materials
5 Pathogens
350
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HISTORY OF THE CONSTRUCTION GRANTS PROGRAM
T. P. O'Farrell
Office of Water Program Operations
U.S. Environmental Protection Agency
Washington, D.C. 20460
ABSTRACT
The 1976 Needs Survey projected that by the year 1990, 34% of the United States
population will be served by secondary treatment and 55% by greater than secondary
treatment. Additional funding over the available $18 billion will be required — $13
billion for secondary, $21 billion for greater than secondary, and $18 billion for new
interceptor sewers. This paper discusses the types of treatment systems that are being,
or will be, employed in the EPA Construction Grants Program and the factors that affect
their selection. Particular attention is given to new technologies. The grants process,
employing the concept of cost-effectiveness, is discussed. In addition to the 1976 Needs
Survey, information for this paper was gathered by interviews with representatives from
the ten EPA Regional offices and the review of over 1000 projects which employ new
technologies. The survey showed the two key factors which impacted the implementation of
a new technology in the Construction Grants Program were its cost-effectiveness and the
level of confidence associated with the use of the system.
INTRODUCTION
The United States Environmental
Protection Agency is primarily a regulatory
organization which was established in
1970. However, included in the responsi-
bilities of the USEPA is the management
of a public works program for the construc-
tion of publicly owned wastewater treatment
plants. With $18 billion in total Federal
funding, the Construction Grants Program
is one of the Nation's two largest public
works programs, second only to the federal
highways program in terms of size.
The EPA Construction Grants Program
was authorized under the Federal Water
Pollution Control Act, as amended in 1972
(Public Law 92-500). This act is the
fourth in a series, the first of which was
passed in 1948. The major public works
program began its effective life in 1956
with annual appropriations limited to $50
million. Originally, individual grants
were limited to 30% of the cost and were
not to exceed $250,000. Although the funds
were limited, this program did represent
the beginning of Federal recognition that
funding aid would be necessary for the
construction of municipal wastewater
treatment systems.
Recognizing the increasing threat of
water pollution caused by insufficient
wastewater treatment and the lack of
communities to fund auich projects, the
Congress in 1966 passed a new law (PL 84-
660). The Federal level of participation
was increased to a range between 40-55%.
Appropriations increased from about $200
million in 1968 to $1 billion in 1971.
Under the grants program authorized by
PL 84-660, nearly 14,000 grants for more
than 5.2 billion Federal dollars were made.
In the late 60's, water quality
standards, exposure of the public to water
pollution issues and resultant enforcement
conferences prompted municipalities and
industries to consider action toward
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reducing the pollution load in their dis-
charges. The greatest input to the improve-
ment of the nation's water came with the
passage of the Federal Water Pollution
Control Act (PL 92-500) in October 1972.
The primary goal of PL 92-500 is to "restore
and maintain the chemical, physical and
biological integrity of the Nation's
waters."
National effluent limitations were
required for all municipal wastewater treat-
ment plants and were to be implemented in
two increments. Initially, municipal waste-
water treatment facilities must attain a
minimum of secondary treatment by July 1,
1977. EPA has defined secondary treatment,
based on a monthly average, as 30 mg/1 of
biochemical oxygen demand and suspended
solids and a pH between 6.0 and 9.0. In
the second level of treatment, all publicly
owned treatment works must achieve "best
practicable waste treatment technology"
(BPWTT) by July 1, 1983. Because of budg-
etary constraints, EPA has established
secondary treatment as the minimum criteria
for BPWTT for those plants that are not
required to meet more stringent water
quality standards. The recently completed
EPA Needs Survey showed that 47% of the
facilities will require a level of treat-
ment greater than secondary effluent. In
these cases, additional BOD, suspended
solids, nitrogen and phosphorus removals
may be required.
In order to attain these goals,
authorization for the Construction Grants
Program was included within PL 92-500. The
Federal share for the cost of the treatment
systems is 75% of the eligible costs.
Localities and many States share the re-
maining capital costs. Industrial users
are required to pay the capital costs for
the portion of the treatment works capacity
they use. Operation and maintenance costs
are shared by the local users. Projects
are selected for funding based on the
States' priority lists. States are re-
quired to revise their lists annually
based on national and State criteria,
severity of the pollution problem, existing
population and the need to preserve high
quality waters.
The grants process is divided into
the following three segments:
Step 1 - Facility planning. Cost-
effective and environmentally sound
projects are developed through considera-
tion of alternatives for treatment plant
size, site, type of process, method of
effluent and sludge disposal, interceptor
sewer routing, etc. Infiltration/Inflow
analyses and sewer systems survey require-
ments must be met; environmental assess-
ments, public input, and consideration of
all the other applicable Federal laws are
required.
Step 2 - Design & Specifications Prep-
aration. Preliminary development of a
proportionate user charge system and
industrial cost recovery must begin. The
end product is a set of detailed drawings,
specifications and cost estimates suitable
for bidding and construction.
Step 3 - Construction. Bids must be
solicited and reviewed and contracts
awarded; on-site inspection, progress
payments and audits are made according to
EPA regulations.
As of January 1977, $12.2 billion of
the authorized $18 billion has been obli-
gated to projects. Projects which have
received funding include: approximately
4500 Step 1 facilities plans for $350
million, 1200 Step 2 designs for $350 mil-
lion, and 2300 Step 3 construction projects
for $10.5 billion. As seen, with 5700
projects yet to be funded for construction
and more projects remaining on State pri-
ority lists, additional funding will be
necessary.
The results of the 1976 Needs Survey
were submitted to Congress on February 9,
1977. In order to serve the sanitary
sewer and treatment needs of the 1990 pop-
ulation, EPA has estimated that approxi-
mately $52 billion will be required. EPA
has recommended to Congress that funds be
authorized over a 10 year period. The
cost of $52 billion for the construction
of municipal wastewater treatment plants
can be divided into $13 billion for sec-
ondary treatment, $21 billion for greater
than secondary treatment and $18 billion
for new interceptors. As ctated earlier,
47% of the facilities will require some
treatment greater than secondary. The
projected $21 billion are for the cost of
the total facility to meet greater than
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secondary, not just that portion that re-
sults in greater than secondary effluent
(i.e., tertiary treatment).
Technologies in the Construction Grants
Program
A review of the present Construction
Grants projects shows that a variety of
technologies, both conventional, new and
innovative, are being planned and construc-
ted to meet the goals of PL 92-500. The
following is a discussion of the factors
that affect the selection of a process,
particularly new processes, the projected
treatment needs (1976 Needs Survey) and
the results of a regional survey on the
types of new systems that are being incor-
porated in the Construction Grants Program.
The regional survey was in response to
inquiries on the extent to which new and
innovative technologies are being used in
the Construction Grants Program. The gen-
eral belief is that there is only limited
use of new technology in the program.
For purposes of discussion, technolo-
gies have been divided into two categories;
conventional and new. New technologies
have been subdivided into proven and un-
proven.
Conventional Technologies - systems
that have been widely employed for the
treatment of municipal wastewaters and
sludges for at least 20 years (trickling
filters, activated sludge, lagoons, anaer-
obic digestion, vacuum filters, etc).
New Technologies
Proven - systems that have been evalu-
ated on a full scale in the United States
in the last 10 years (rotating bio-disc,
oxygen activated sludge, air nitrification,
lime chemical clarification, activated
carbon, land application, oxidation dit-
ches, etc.)
Unproven - systems that have not been
evaluated on a full scale in the United
States (sludge pyrolysis, co-pyrolysis,
aquaculture, use of solar energy, energy
recycling, alternative methods of disin-
fection, etc.)
In addition, there are a number of
modifications to conventional systems that
will be considered as new technologies.
The author realizes that systems such as
land treatment have been employed for many
years in the United States. However, be-
cause these types of systems have not been
widely used by sanitary engineers, they
must overcome the same obstacles that face
new technologies. For this reason, these
technologies have been classified as "new"
in this paper.
Factors that Effect the Process Selection.
There are two key factors which impact
the implementation of a specific system in
the Construction Grants Program — cost-
effectiveness and the level of confidence
associated with the system. Successful
implementation generally occurs when the
system has been sufficiently developed and
can economically compete with other systems
in a cost—effective analysis.
Section 212 of PL 92-500 requires that
applicants for construction grants provide
sufficient information to demonstrate that
the proposed system is the most cost-
effective alternative for the degree of
treatment required and disposal of waste
solids. The cost-effectiveness analysis
is conducted in the Step 1 facilities plan.
The basis for the cost-effectiveness
analysis is a comparison of the capital
and O&M expenses for the project over a
twenty year planning period. All grantees
are required to consider land application
and other forms of wastewater reuse as
part of the cost-effective analysis. The
Step 1 facilities plan, which includes the
cost-effective analysis, is generally per-
formed by the consulting engineer hired by
the grantee, accepted by the municipality
and approved by the State and EPA review-
ing officials.
In order to aid the consulting engi-
neer in performing the cost-effective
analysis, EPA has published a series of
documents. One such publication, "Alter-
native Waste Management Techniques for
Best Practicable Waste Treatment" provides
information on conventional and new
systems for the treatment of wastewater
and handling of residual sludges. It
should be emphasized again that EPA does
not dictate what processes should be used,
only that the selected system must be
cost-effective to meet the effluent quality
required for the protection of the re-
ceiving stream. Cost-effectiveness is
the key element in the selection of the
treatment systems. Non-monetary factors
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(social and environmental) are accounted
for descriptively in the cost-effectiveness
analysis in order to determine their signi-
ficance and impact. Both monetary and non-
monetary factors are considered in the final
selection of the treatment system in the
cost-effectiveness analysis.
New technologies must be developed
sufficiently in order that their cost-
effectiveness and reliability can be dem-
onstrated. For conventional systems, this
type of information and experience is avail-
able to the consulting engineer. In reality,
a new technology system should only be
selected over a conventional system if the
system employing new technology is less
costly and more environmentally acceptable.
The procedure for obtaining the required
information for new systems, particularly
new-unproven systems, includes laboratory
tests, bench tests, pilot plant studies
and full scale performance evaluations.
Full scale evaluation is hampered by the
lack of research and development funds
available for such a study. The EPA
Construction Grant Regulations in section
35.908 provide that new processes, even
those which have been demonstrated under
less than full scale conditions, may be
utilized in the construction of treatment
plants. However, as a practical considera-
tion, there may be a reluctance on the part
of the potential designers, users and re-
viewers to utilize new technologies until
confidence is gained for dissemination of
data from successful full scale demonstra-
tions .
In addition to the difficulties en-
countered by unproven new technologies,
certain constraints exist for the imple-
mentation of new proven technologies that
have been demonstrated on a full scale.
The most obvious constraint is the prefer-
ence for the selection of conventional
processes by grantees and consultants be-
cause of their public acceptance and proven
capability to meet effluent standards at a
known cost. A recent EPA survey of the use
of new technology, which included interviews
with EPA Regional and State officials, has
indicated six major reasons inhibiting the
use of demonstrated new technology at the
municipal level. First, familiarization and
information transfer on demonstrated new
technologies to gain public and consultant's
acceptance, has been either slow or insuf-
ficient. Second, lack of adequate operating
and cost data for new technology makes it
difficult to develop an adequate cost-
effectiveness alternatives comparison with
conventional technology. Third, there is
no incentive to consider and use (i.e.,
risk) new technology if the conventional
technology appears to be adequate. Fourth,
utilizing ajnew technology will often re-
quire expensive retraining of operating
personnel. Fifth, many new and alternative
technologies are simply not cost-effective
and accordingly, cannot be funded by the
grants program. And finally, EPA and State
resources to review each facilities plan
have been insufficient to fully evaluate
the extent to which alternative technolo-
gies are considered.
The degree of familiarity that a
State, EPA Regional Office, and most impor-
tant, the consulting engineer has with a
new technology, usually determines whether
a new technology is selected. With over
8000 active grant projects (approximately
60% include treatment systems), a massive
information transfer problem is created.
A State, Region, or consultant often is
not cognizant or familiar with developments
of new technologies in other areas of the
country. The problem of familiarity with
a new technology is more acute for the
smaller consulting firms. They are usually
regional, have smaller staffs, and are
involved in a fewer number of projects.
Accordingly, smaller firms are less likely
to know about or be familiar with demon-
strated new technologies in other regions
of the country.
This lack of information can also
produce additional problems. The consult-
ant or reviewing official may not be aware
of difficulties that others have encoun-
tered with systems the consultant or re-
viewing official is presently recommend-
ing, designing, or approving.
An important constraint on imple-
mentation of sufficiently developed new
technology is the preference for con-
ventional systems by consultants. The
survey corroborated other findings that
consultants, needing to "serve" clients by
ensuring projects achieve required effluent
levels, will select conventional technolo-
gies. The fact is that the only product
consultants can offer is their reputations.
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Another important factor is that consult-
ants may be able to realize greater profits
by utilizing existing designs for con-
ventional systems as opposed to redesigning
for new technologies.
The fact that municipalities must bear
the full financial burden of operating and
maintaining treatment plants, as well as
the 25% local share for capital costs in
most cases, tends to add to the reliance on
conventional technologies. The survey in-
dicated that many municipalities, especially
the smaller ones, can only afford low salary
levels for plant operating personnel and low
maintenance costs. Such a situation implies
low skill level for operating personnel,
which would preclude the effective use of
some new technologies requiring a higher
degree of sophistication to operate. In
addition, municipalities are required to
meet the effluent requirements of their
permit. The threat of legal action as a
result of a permit violation tends to compel
municipalities to accept conventional
systems.
Other constraints can be found at the
State and Federal levels. EPA pressure to
obligate Construction Grants funds quickly
has resulted in greater implementation of
conventional systems. This factor along
with the lack of sufficient personnel at
the State and Federal levels has encouraged
consultants to recommend conventional
systems which are more common to the indi-
vidual reviewer.
Certain States have developed lists of
approved processes and methods. Other
states do not have such lists, but a pro-
posal for funding of a large sized facility
employing sufficiently demonstrated but new
technologies would run the risk of not being
favorably reviewed for grant funding.
An important factor which has influ-
enced the utilization of some new technol-
ogies within the grants program has been
the publicity or "salesmanship" which has
been provided with the new system. Processes
which have been developed and marketed by
private industries such as pure oxygen
activated sludge and rotating biological
filters, have received wider acceptance
than systems that required less private
industry input, such as land treatment.
1976 Needs Survey.
The 1976 Needs Survey provides infor-
mation on the number and types of treat-
ment systems that will be enlarged, up-
graded or constructed to meet the goals of
PL 92-500. The Survey projects the treat-
ment requirements and shows that by the
year 1990, 34% of the population will re-
quire secondary treatment and 55% will re-
quire greater than secondary. Greater
than secondary effluent does not necessarily
mean that tertiary treatment will be re-
quired, only that an effluent greater than
that defined by EPA as secondary effluent
(30 mg/1 of BOD and 30 mg/1 of SS) will be
necessary. Eleven percent of the population
will remain unsewered.
Table 1 summarizes the types, number
and flows of systems that are projected to
treat wastewater in the United States. The
category labeled "Other" includes systems
which were not specifically labeled on the
survey form. These systems may include
both secondary and tertiary treatment
systems.
As seen in Table 1, the majority of
the wastewater will be treated by activated
sludge systems. For the three specific
types of secondary systems (activated
sludge, trickling filter and oxidation
ponds), activated sludge includes 55% of
the facilities and nearly 80% of flow.
Compared to oxidation ponds and activated
sludge, the use of trickling filters is
expected to decrease. Many trickling
filter plants are being abandoned and re-
placed by other forms of secondary treat-
ment because of the concern by engineers
that trickling filter plants cannot con-
sistently meet the secondary effluent
requirements.
The fact that oxidation ponds are 9%
of the flow and 34% of the facilities is
understandable since over half of the
treatment plants in the Nation have flows
less than 0.1 MGD.
Tertiary treatment systems are also
included in Table 1. As seen, filtration
has the highest planned use. The use of
the AWT systems (lime treatment, break-
point chlorination, ion exchange) is very
limited. The number of land treatment
systems is considerably lower than those
irojected by other data which will be dis-
cussed later.
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The information on tertiary treatment
can be compared with Needs Survey data on
treatment plants that reported "greater
than secondary required." The survey
showed that 9036 facilities will require an
effluent quality greater than that defined
by EPA as secondary effluent (30 mg/1 of
BOD and 30 mg/1 of SS). Assuming 19,000
treatment plants, it can then be projected
that 47% of treatment plants will require
"greater than secondary." Population
projections show that the 47% facilities
correspond to 55% of the projected sewered
population. It is important to point out
again that "greater than secondary" does
not necessarily mean that tertiary treatment
will be required. This fact is shown in
Table 2. The 9036 facilities that responded
"yes" to the question of "greater than
secondary" were sampled to determine their
projected effluent quality (Table 2).
Effluent quality data from all responding
plants was not provided on the survey forms.
However, if as a minimum, additional BOD
removals were required by all responding
plants, the data in Table 2 would represent
85% of those plants where greater than
secondary would be required.
While 7704 facilities must provide an
effluent with less than 30 mg/1 of BOD,
only 6271 facilities must do better than
30 mg/1 of suspended solids (SS). These
results are consistent with many permit
limitations, based on water quality
standards, where BOD requirements are gen-
erally lower than SS requirements. Assuming
that filtration would be required to attain
a BOD of less than 20 mg/1, then the 4927
facilities in Table 2 are consistent with
4993 filtration facilities in Table 1.
Apparently, facilities expect to attain
less than 5 mg/1 of BOD by reducing the
suspended solids to less than 10 mg/1.
Facilities requiring phosphorus re-
moval are also presented in Table 2. Phos-
phorus removal was assumed to be required
when the effluent limitation was less than
2 mg/1 of phosphorus. As seen, only 56
plants require phosphorus concentrations
less than 0.5 mg/1 and 180 plants require
phosphorus concentrations between 0.5 and
0.9 mg/1. This data is consistent with the
two-stage lime projects (70) listed in
Table 1, since two-stage lime would gen-
erally be applied when the effluent quality
was less than 0.5 mg/1 of phosphorus. The
majority of the plants that need phosphorus
removal (83%) fall in the 1-2 mg/1 range
which can be produced by chemical addition
to the secondary system. Chemical addition
to the secondary system will also result in
BOD and SS concentrations less than 30 mg/1
At the present time, chemical addition to
primary or secondary systems is used at
approximately 400 facilities.
Nitrogen requirements are shown by
the ammonia and total nitrogen concentra-
tions in Table 2. The data show that the
majority of the plants will require ammonia
conversion to nitrate and not total nitro-
gen removal. Table 1 reported 653 separate
biological nitrification systems while
Table 2 lists 2666 projects requiring
ammonia removal. The addition of ion ex-
change, breakpoint chlorination or
projected ammonia stripping cannot approach
the number of systems reported in Table 2.
It would appear that the majority of the
nitrification systems are single-stage
systems such as oxidation ditches or
extended aeration plants. The need for
high removals of total nitrogen (less than
5 mg/1) is small with approximately 200
facilities. By comparing these results
with facilities which must provide an
effluent phosphorus concentration of less
than 1 mg/1 and suspended solids of less
than 5 mg/1, it can be seen that the highly
sophisticated AWT systems are probably
limited to 200 facilities. As mentioned
earlier, many facilities expect to attain
a BOD less than 5 mg/1 by reducing the
suspended solids to less than 10 mg/1.
However, as seen in Table 1, the use of
activated carbon (BOD less than 5 mg/1) is
projected for 295 facilities.
Needs Survey information on sludge
processes is presented in Table 3. As
seen, the category labeled "other" contains
more projects than any other single
process. It is assumed that most of these
projects include some type of land disposal
of sludge. The increased emphasis on re-
ducing energy usage has affected the use
of incineration. However, the incinera-
tion industry has responded by the develop-
ment of alternative systems to decrease
energy consumption, which will be dis-
cussed later.
EPA Survey on New Technologies.
Congressional committee hearings on
science and technology raised questions
concerning the utilization of new tech-
356
-------
nologies in the EPA Construction Grants
Program. As a result, a survey was initia-
ted in November 1976 to determine what new
technologies were being used and what
factors influenced their implementation.
Each of the ten EPA Regional Offices was
supplied with forms containing new waste-
water and sludge treatment systems
(Attachment 1). Forms were completed for
projects (completed Step 1, Step 2, and
Step 3) which included a specified system
listed on the form. In addition, systems
which were considered new in the opinion of
the EPA official but were not en the list
were included. EPA headquarters personnel
visited each Regional Office, completed the
forms and discussed the results with the
EPA regional staff. In addition, EPA head-
quarters staff had the opportunity to
interview some State representatives.
The data collected from the survey
has been summarized in Tables 4 through 8.
In addition to the presented information,
the survey found a number of systems being
employed that are not included in the
tables. These included, screens to replace
primary settlers, use of solar energy,
digester gas utilization, heat recovery,
automatic computer control systems, aqua-
culture, electric power generation in a
gravity sewer and alternative disinfection
systems such as ozone. Over 1000 projects
were identified in the survey as employing
new technology. Because of time constraints
and work loads, not all projects that
included new technologies were reviewed and
summarized. Emphasis was placed on provid-
ing information on different types of
systems and as a result, all projects which
included systems with higher usage were
not reviewed. This was the case with
systems such as rotating biological con-
tactors (RBC's) and oxidation ditches
whose use has been widespread.
Systems that are used to achieve
secondary effluent are included in Table 3.
Land application, which achieves greater
than secondary effluent was also included
in Table 3. The data shows a widespread
use of oxygen activated sludge, RBC's and
oxidation ditches for secondary treatment.
All of these types of systems are
marketed by private firms. Oxidation dit-
ches and RBC's are the two systems whose
use has increased rapidly in the United
States. A draft report by William F.
Ettlich of Gulp, Wesner and Gulp titled
"A Study of Oxidation Ditch Plants and
Technology" lists 544 installations in the
United States. Mr. Ettlich lists 5 reasons
for the increased use of oxidation ditches.
1. Construction costs equal to or
less than competitive treatment processes.
2. Plants require a minimum of
mechanical equipment.
3. Plants appear to perform reason-
ably well even with minimum operator
attention, primarily due to conservative
design.
4. Waste sludge is relatively
nuisance free and is readily disposed of
at most plants.
5. Plants generally do not generate
odors even under poor operating conditions.
RBC's have the capability to be retro-
fitted into an existing facility for up-
grading or enlarging. These units also
lend themselves toward modular design.
Pure oxygen activated sludge systems have
been developed and promoted by several
large companies. These systems have been
marketed based on retrofitting to increase
capacity or capability of handling high
organic strength waste.
The information on land treatment
systems in Table 3 shows that far more
land application systems are being employed
than is shown in the land treatment data
in Table 1. Table 1 projects 265 land
treatment systems by 1990 while Table 3
shows 242 projects at the completed Step 1,
Step 2 or Step 3 stages. The data in
Table 3 was a sampling of regional projects
and did not include all land application
projects. As seen, land application is
used more in the West where water supplies
are limited. Activated Biological Filters
were not found in the northeast section of
the United States.
Projects for the nitrification of
municipal wastewater are presented in
Table 5. As seen, separate stage air
systems and RBC's were found to be the
most widely used. Although Table 5 only
lists 11 oxidation ditch systems designed
for nitrification, many oxidation ditch
systems are expected to produce a nitri-
fied effluent. The same is true of many
extended aeration systems which could be
listed under "combined air."
357
-------
Table 6 lists various tertiary treat-
ment systems. This information is con-
sistent with the data shown in Table 1. As
seen, filtration is the highest used form
of tertiary treatment. Microscreens are
also being employed to improve effluent
quality in small facilities. The data shows
that the use of the AWT systems (lime clari-
fication, NH stripping, activated carbon,
breakpoint chlorination and ion exchange)
has not been widespread. This data is also
supported by the Needs Survey Data in Table
1. The effluent quality data in Table 2
shows that the need for the AWT systems
(high levels of phosphorus, SS, BOD, and
total nitrogen) apparently does not exist.
These systems were developed in the
late bO's and early 70's within the Advanced
Waste Treatment Research Program. The major
objective of this program was to develop
treatment processes for maximum removal of
contaminants and repeated reuse of the
Nation's waters. The level of treatment
produced by these processes is not necessary
to produce the effluent qualities now re-
quired. Because of the additional expense
to build, operate and maintain these types
of systems, the application of these systems
will no doubt remain limited.
Similar comments can be made concern-
ing the use of the independent physical/
chemical systems for wastewater treatment.
Data on these systems is presented in
Table 7. A number of factors can be
attributed to the limited use of this type
of treatment.
1. Effluent standards do not require
the levels of treatment produced from these
systems.
2. Energy usage, because of the
recalcination of lime and regeneration of
activated carbon, is extremely high.
3. Systems for nitrogen removal have
not been demonstrated on a full scale.
4. Systems are generally not cost-
effective as compared to land application
when stringent effluent qualities are re-
quired .
The draft EPA report "Energy Conser-
vation in Municipal Wastewater Treatment"
by Gulp, Wesner and Gulp Consulting Engi-
neers, compared the energy usage for a
conventional treatment system and an IPC
system to produce secondary effluent at a
flow of 30 MGD. The conventional system
which included activated sludge with
incineration of the waste solids required
31,600 x 10 BTU/yr and 10,665 x 10 KWH/yr
of total energy. The IPC system which
included incineration of the chemical
sludge and regeneration of activated
carbon required 275,000 x 10^ BTU/yr and
10,777 x 10 KWH/yr of total energy. The
escalating costs of fuel in addition to
the availability, which must be considered
in the cost-effective analysis, is a
major factor that will limit the use of
these systems.
The information on solids processing
projects is included in Table 8. Compared
to wastewater treatment systems, this
information is relatively small. Heat
treatment systems appear to be the most
widely used. Of all the systems, including
wastewater treatment, heat treatment
systems were frequently identified as not
operating properly.
Concern for odors and possible health
effects in projects employing land disposal
of sludge has led to the use of chlorine
oxidation and lime stabilization. The
possible production of chlorinated hydro-
carbons during chlorination of organic
sludges has resulted in additional studies
on this system. Sludge composting has
become increasingly popular since compost-
ing raw sludge without excessive odors has
been demonstrated.
Energy consumption for solids proces-
'sing has had major impact on systems
presently being considered. Disposal of
sludge can be energy intensive if fuels
are required. Sludge is also the only by-
product which offers the potential for
energy recovery. Methane gas, the by-
product of anaerobic digestion, is being
used for power generation and direct
coupled combustion engines. The energy
report by CWC shows that methane gas from
anaerobic digestors could provide 80% of
the electrical energy requirements of the
primary and secondary treatment systems.
The volatile fraction of the waste
solids are a potential source of energy.
To reduce fossil fuel requirements for
incineration, increased attention has been
given to filter presses to reduce the
liquid fraction for incineration without
auxiliary fossil fuels. Data from Enviro-
tech Corporation shows that 22 facilities
358
-------
are being constructed to employ heat re-
cycling to further decrease the water
content prior to incineration.
Pyrolysis of sewage sludge, because of
its potentially lower fuel inputs and
lower air emissions, is currently being
evaluated to handle the sludge for the New
York/New Jersey area.
Co-incineration with solid waste is
being used to reduce fossil fuels. Co-
pyrolysis of sewage sludge and solid waste
is being planned for the Contra Costa waste-
water treatment plant. Studies have shown
that sufficient energy can be developed for
co-pyrolysis to supply the average demand
for a 30 MGD AWT facility.
SUMMARY
Treatment systems, employing new
technologies and particularly new unproven
technologies, must overcome a series of
obstacles before they are accepted and
utilized by consulting engineers and muni-
cipalities in the Construction Grants
Program. The use of these systems was
found to be a function of their familiarity
and acceptance by engineers, adequate cost
information, and needs to attain desired
effluent qualities. Familiarity and
acceptance can be accelerated by an active
sales program by private industry.
The criticism that new technologies
are not being employed in the Construction
Grants Program is not supported by our
recent surveys. At the present time,
approximately 2,500 Step 2 and 3 grants
include treatment plants. The EPA survey
of regional files showed that 697 projects,
or 28%, are using new technologies. The
percentage is the minimum amount, since
not all new technology projects were
identified in the survey.
The use of Advanced Waste Treatment
plants to attain very high removals of BOD,
suspended solids, phosphorus and total
nitrogen appears to be limited to 200 of
the 19,000 facilities that require up-
grading, enlarging or construction.
Projected effluent limitations and high
costs of such facilities limit their appli-
cation.
The amount of land application
projects will be higher than previously
projected. Limited water supplies for
irrigation in various sections of the
United States will probably have the
greatest impact on the utilization of this
technology. The use of land treatment only
in those situations where very high
removals of pollutants are required, based
on projected effluent limitations, would
be limited to approximately 200 facilities.
Our recent survey showed approximately
350 land treatment systems out of 2,500
treatment plant projects.
Compared to wastewater treatment
technologies, utilization of new sludge
handling and disposal techniques in the
program is lagging. This apparent delay
is a result of the lack of new systems to
be demonstrated or their unsuccessful
demonstration. Successful demonstration of
energy savings and safe ultimate disposal
techniques will aid in correcting this
situation.
REFERENCES
Pound, C.E., Crites, R.W., and Smith, R.G.,
"Cost-Effective Comparison of Land Ap-
plication and Advanced Wastewater Treat-
ment," EPA 430/9-75-016; Office of Water
Program Operations, Environmental Pro-
tection Agency, November 1975.
359
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TABLE 1
1976 NEEDS SURVEY
TREATMENT PROCESSES
TYPE OF
SYSTEM
IN USE
NUMBER OF
PROJECTS
UNDER
CONSTRUCTION
NUMBER OF
PROJECTS
PLANNED
NUMBER OF
PROJECTS
ACTIVATED SLUDGE
TRICKLING FILTER
OXIDATION PONDS
LAND TREATMENT
OTHER
NUMBER OF
PROJECTS
3,550
1,727
3,504
51
1,883
NUMBER OF
PROJECTS
559
42
214
10
261
NUMBER OF
PROJECTS
5,847
206
2,527
204
4,001
TOTAL
NUMBER OF FLOW
PROJECTS m3/DAY X 1Q3
9,956
1,975
6,245
265
6,145
100,738
13,758
11,507
1,652
64,076
-------
TABLE 1 (CONTINUED)
1976 NEEDS SURVEY
TREATMENT PROCESSES
TYPE OF
SYSTEM
FILTRATION
ACTIVATED CARBON
TWO STAGE LIME
BIOLOGICAL NITRIFICATION
BIOLOGICAL DENITRIFICATION
ION EXCHANGE
BREAKPOINT CHLORINATION
IN USE
UNDER
CONSTRUCTION PLANNED
TOTAL
NUMBER OF
PROJECTS
535
13
15
32
11
0
25
NUMBER OF
PROJECTS
207
13
7
37
7
3
NUMBER OF
PROJECTS
4,251
269
48
584
120
3
82
NUMBER OF
PROJECTS
4,993
295
70
653
138
6
107
FLOW
m3/DAY X
48,383
3,400
1,609
15,193
3,596
628
-------
TABLE 2
1976 NEEDS SURVEY
TREATMENT PLANS AND EFFLUENT QUALITY
BOD EFFLUENT
mg/1 tt OF PLANTS
SS EFFLUENT
mg/1 tf OF PLANTS
TOTAL P
mg/1 tt OF PLANTS
TOTAL N
mg/1 # OF PLANTS
AMMONIA-N
mg/1 ff OF PLANTS
<5
5-9
10-19
20-29
TOTAL
796
1134
2997
2777
7704
<5
5-9
10-19
20-29
122
1559
2497
2093
6271
<0.5
0.5-0.9
1-2
56
180
1186
1422
<1
1-4.9
5-9.9
10-15
3
198
110
77
388
1-1.9
2-5
89
1098
1479
2666
-------
TABLE 3
SLUDGE PROCESSES 1976 NEEDS SURVEY
(Number of Projects)
ANAEROBIC DIGESTION
HEAT TREATMENT
AIR DRYING
DEWATERING
INCINERATION
LANDFILL
LAND SPREADING
OTHERS
IN USE
UNDER
CONSTRUCTION
PROJECTED
TOTAL
4803
165
5272
1147
1316
1724
584
5939
296
50
286
241
105
127
36
396
3377
124
3910
1701
913
1784
322
4005
8476
339
9468
3089
2334
3635
942
10,340
TABLE 4
BIOLOGICAL SECONDARY TREATMENT
(Number of Projects)
TREATMENT PROCESS
OXYGEN AERATION
RBC
PLASTIC MEDIA
ACT. BIOLOGICAL FILTER
OXIDATION DITCH
LAND APPLICATION*
'ACHIEVES EFFLUENT GREATER THAN SECONDARY
EPA REGIONS
II III IV V VI VII VIII IX X TOTAL
6
6
18
10
8
8
14
1
11
18
5
6
1
16
9
2
2
11
25
10
33
7
2
31
14
5
1
3
3
13
31
5
24
5
5
36
7
2
6
4
10
17
9
4
1
4
15
92
9
12
1
15
22
44
81
121
24
35
176
242
363
-------
TABLES
NITRIFICATION
(Number of Projects)
TREATMENT PROCESS
SEPARATE STAGE AIR
COMBINED AIR
SEPARATE STAGE O2
COMBINED O2
RBC
DITCH
ACT. BIOLOGICAL FILTER
EPA REGIONS
I II III IV V VI VII VIII IX X
2
3
1
5
2
4
1
6
6
11
1
7
4
7 10
3
6 2
5 13
1
2
5 3
1
1 2
6
1
5 10 2
1
1
1 1
TOTAL
60
10
16
1
39
11
5
TABLE 6
TERTIARY TREATMENT
(Number of Projects)
TREATMENT PROCESS
LIME CLARIFICATION
ALUM CLARIFICATION
FILTRATION
MICROSCREENS
AMMONIA STRIPPING
POWDERED CARBON
GRANULAR CARBON
B.P. CHLORINATION
ION EXCHANGE
EPA REGIONS
I II III IV V VI VII VIII IX X TOTAL
3
5
1
1
1
1
283
6 17 9
10 2
1
2 8
3
2
1 3
17 14 14
19
1
1
2 1
1
3
2
9
6
1
5
1
14
1
3
4
1
1
5
3
15
1
2
33
6
120
32
6
3
26
6
4
364
-------
TABLE 7
INDEPENDENT PHYSICAL/CHEMICAL
TREATMENT
(Number of Projects)
TREATMENT PROCESS
LIME CLARIFICATION
ALUM CLARIFICATION
FILTRATION
GRANULAR CARBON
B.P. CHLORINATION
ION EXCHANGE
EPA REGIONS
II III IV V VI VII VIII IX X
TOTAL
2
2
1
3 1
2
5 1
5 1
2
1 1
1
2 1
2 1
1
3
1
2
2
11
4
13
12
2
1
TABLE 8
SOLIDS PROCESSING
(Number of Projects)
TREATMENT PROCESS
SLUDGE COMPOSTING
CHLORINE OXIDATION
HE AT TREATMENT
LIME STABILIZATION
FILTER PRESS
BELT FILTER
PYROLYSIS
CO-PYROLYSIS
CO-INCINERATION
FERTILIZER
EPA REGIONS
V V VI VII VIII IX X TOTAL
3
3
4
1
4
1
2
1
4
1
2
1
1
1
2
2
3
5
2
2
1
1
3
2
1 10
1
4
1 2
2
5
1 1 1
22313
1 1 1
1 2
1
2
2411
9
6
35
8
12
9
2
2
11
15
365
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ATTACHMENT I
Project No:
EPA Regions:
Grant Applicant:_
Name of Preparer:_
Location:
*Check one:
Telephone No:
PL - 92-500 Project Step 2 Grant Awarded
PL - 92-500 Project Step 3 Grant Awarded
Old Law Project Step 1 Study Completed
*Date of award (bid)
*Design average flow (MGD)_
WASTEWATER:
OXYGEN ACTIVATED SLUDGE
SPECIFY PROCESS
OTHER OXYGEN SYSTEM
(specify)
ROTATING BIOLOGICAL CONTACTOR (Disc)
for BOD REMOVAL _
for NITRIFICATION
OXIDATION DITCH
ACTIVATED BIO FILTER
PLASTIC MEDIA TRICKLING FILTER
LAGOON (POND) UPGRADING
WITH ROCK FILTERS
INTERMITTENT SAND FILTER
SUBMERGED SAND FILTER
OTHER (SPECIFY)
LAND APPLICATION (TREATMENT)
CROP IRRIGATION
(or slow rate systems)
RAPID INFILTRATION ___^J~
OVERLAND FLOW
CARBON ADSORPTION
GRANULAR
POWDERED
NEW FILTRATION TECHNIQUES _
(NOT RAPID SAND FILTERS)
MULT I OR DUAL MEDIA
SPECIFY
CARBON REGENERATION
LIME TREATMENT
WITH BIOLOGICAL TREATMENT
AFTER BIOLOGICAL TREATMENT (tertiary)
BEFORE NITRIFICATION
PHYSICAL - CHEMICAL
(no biological treatment)
RECARBONATION
ION EXCHANGE
REVERSE OSMOSIS
AMMONIA STRIPPING
TUBE SETTLERS
MICRO SCREENS
NITRIFICATION
SUSPENDED GROWTH (TANKS)
ATTACHED GROWTH (FILTERS) _
WITH AIR WITH OXYGEN"
FLUDIZED BEDS
DENITRIFICATION
WASTEWATER:
UTILIZATION OF SOLAR ENERGY
(COLLECTORS OR CELLS)
NEW DISINFECTION TECHNOLOGY
OZONE
ULTRA VIOLET LIGHT
BROMINE CHLORIDE
OTHER
SPECIFY
DECHLORINATION
SULFUR DIOXIDE
OTHER
SPECIFY
STORM AND COMBINED SEWER
OVERFLOW TREATMENT
SPECIFY TYPE
NON-SEWERED TREATMENT
SPECIFY TYPE
OTHER INNOVATIVE PROCESSES
SPECIFY
SLUDGE:
CO - INCINERATION
CO - PYROLYSIS PYROLYSIS _
REGIONAL TREATMENT OF SEPTAGE
TANK PUMPINGS
SLUDGE COMPOSTING
LIME CONDITIONING
UTILIZATION OF INCINERATOR ASH FOR
SLUDGE CONDITIONING
CHEMICAL FIXATION (STABILIZATION)
OF SLUDGE
SPECIFY PROCESS
COMMERCIAL SOIL CONDITIONER/
FERTILIZER PRODUCTS
DIGESTER GAS DRIVER INTERNAL
COMBUSTION ENGINES
NEW SLUDGE DEWATERING TECHNIQUE
HEAT TREATMENT
FILTER PRESS
BELT FILTER
UTILIZATION OF WASTE HEAT _
SPECIFY
OTHER INNOVATIVE PROCESSES
SPECIFY
COMPUTERIZED PROCESS CONTROL
SUSPENDED GROWTH (TANKS)
ATTACHED GROWTH (FILTERS)
COMBINED NITRIFICATION-
DENITRIFICATION
WASTEWATER REUSE
GROUND WATER RECHARGE
RECREATIONAL REUSE
INDUSTRIAL REUSE
OTHER (SPECIFY)
DISCUSSION
OTHER INFORMATION AVAILABLE ON THE TECHNOLOGIES (PROCESSES) CHECKED ABOVE (VARIATIONS,
PECULIAR CIRCUMSTANCES, ETC )
366
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UTILIZATION OF A FEDERAL ACT (PL 92-500) IN COORDINATION
WITH GEORGIA'S WATER QUALITY CONTROL PROGRAM
J. L. Ledbetter
Director, Environmental Protection Division
Georgia Department of Natural Resources
Atlanta, Georgia
The 1972 Federal Water Pollution Control Act (PL 92-500) instantly impacted the
various State water pollution control programs in the United States. At first the
sudden shift of significant statutory authorities from a State function to a Federal
function created considerable controversy and confusion; however, as time passed, the
Federal and State roles were clarified and progress is being made toward abatement of
water pollution throughout the Nation. The State of Georgia had an active and effective
water pollution control program which had been initiated in 1964. Through the addi-
tional financial support to the State's program provided by Titles I and II of
PL 92-500, Georgia improved its water quality monitoring network and data processing,
including computer modelling. In addition, using the additional legal authorities
established under Titles III and IV of PL 92-500, Georgia strengthened its enforce-
ment program through utilization of the permit program and more stringent levels of
treatment. By 1977 sufficient progress has been made by Georgia's water quality
control program, in coordination with PL 92-500, to enable the State to meet water
quality standards for almost all rivers, lakes, and estuaries.
The enactment of the 1972 Federal
Water Pollution Control Act (PL 92-500) by
the U. S. Congress over a Presidential
veto established a far-reaching complex
national commitment to eliminate water
pollution problems in the United States.
Instantaneously the water pollution control
program was politicized to an unprecedent-
ed degree. Prior to PL 92-500, the indi-
vidual States had used various approaches
to regulate the discharge of pollutants
from industrial and governmental oper-
ations within their own boundaries; how-
ever, this role was superseded by the
U. S. Environmental Protection Agency(EPA)
under PL 92-500. Simultaneously the Act
implemented another precedent for the
program - the concept of contractual
obligation and the authorization for EPA
to proceed with an eighteen billion dollar
construction grant program. This es-
tablishment of a strong Federal role and
authorization of the $18 billion for 75
percent construction grants assured a high
level of interest and involvement by pol-
iticians from the Federal, State, and
local government levels.
No single piece of environmental
legislation in the United States' history
has provoked as much interest and contro-
versy as PL 92-500. For the past four
years, the various professional, technical
and trade journals and publications have
been filled with articles on this subject.
In addition, thousands of governmental
publications and newspaper articles have
concentrated on the water pollution con-
trol program. During this period, numer-
ous conferences and seminars have been
conducted on the subject. A significant
portion of this attention to the program
has been in a negative tone with sharp
criticism leveled at the Federal EPA for
its administration of the program. Much
of this criticism has been related to the
delays encountered in the construction
grants program which have delayed the
367
-------
abatement of pollution from publicly owned
wastewater treatment works. Significant
problems have occurred in the development
and implementation of effluent limitations
for various industrial dischargers which
could be considered reasonable and ac-
ceptable to the industrial community. The
overly optimistic deadlines in the Act for
certain accomplishments have been criti-
cized.
Section 315 of the Act established
the National Commission on Water Quality
and required a three-year study. Fifteen
million dollars were authorized for the
Commission to investigate and study the
technological aspects as well as the
economic, social, and environmental
effects of the far-reaching objectives of
the Act. To a great extent, the Com-
mission's study and report resulted in
additional controversy for the program.
Since early 1974, numerous Congres-
sional committees and subcommittees have
conducted investigations and hearings in
an effort to define problems related to
this program and to consider possible
corrective actions. In late 1976, the two
houses of Congress failed to agree on any
amendments to PL 92-500; therefore, no
significant amendments have been made to
the Act. The debates and controversies
surrounding PL 92-500 have continued into
1977.
A purpose of this paper is to present
some positive aspects and accomplishments
during this controversial period, specifi-
cally related to the State of Georgia.
Although some of the deadlines and goals
of PL 92-500 have not been met, sub-
stantial progress continues to be made
toward abatement of water pollution.
To place the impact of PL 92-500 in-
to proper prospective for the Georgia
water quality control program, a few
facts regarding Georgia and the State's
program prior to 1972 must be presented.
Georgia, one of the original thirteen
colonies, is located on the east coast
in the southeastern portion of the United
States. With an area of approximately
152,810 square kilometers (59,000 square
miles), Georgia is the largest State east
of the Mississippi River. The State has
a population of about five million
with one third of the population located
in the Atlanta area. No rivers flow into
Georgia from other States; however, numer-
ous streams originate in the State and flow
in a southerly direction. Some of the
rivers flow into the Atlantic Ocean while
others flow into Florida or Alabama and
thence to the Gulf of Mexico. Most of the
State's population live in the northern
half of the State where the streams are
small and water quality problems are more
severe because of these population
pressures. The State does receive an
annual rainfall of about 1219 mm (48
inches).
Prior to 1964, Georgia had made
limited efforts to control water pollution;
however, following enactment of the 1964
Georgia Water Quality Control Act an
effective program was implemented. Begin-
ning in early 1965, a technical staff of
engineers, chemists, and biologists
located and inventoried wastewater dis-
chargers in the State. Ambient water
quality standards and stream use classifi-
cations were established for the State's
streams in 1966 and 1967. Wastewater dis-
chargers were placed on schedules to
install treatment facilities. In general,
the local governments and industries were
required to provide 85 percent reduction
of organic waste loads as measured by bio-
chemical oxygen demand (BOD) and to elimi-
nate the discharge of toxic pollutants.
The schedules established the end of 1972
as the target date for installation of
these treatment facilities.
Less than 10 of the 440 industries
discharging significant quantities of
wastewater directly to streams in the
State failed to meet the 1972 deadline.
In general, the installed treatment
facilities provided the level of treat-
ment, five years in advance, which was
required by July 1, 1977 in PL 92-500.
With local governments, the progress was
far less successful. There were 480
publicly owned wastewater treatment works
in Georgia which serve a population of
2.9 million or about 60 percent of the
State's population. These publicly owned
wastewater treatment works have a designed
capacity of 2.4 x 106 m3/d (637 mgd) and
are currently treating approximately
1.5 x 106 m /d (400 mgd) of wastewater.
368
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Financial and management problems hampered
the efforts to correct water pollution
problems in local governments. Prior to
the enactment of PL 92-500, there had been
limited financial assistance from the
Federal government.
In retrospect the enactment of
PL 92-500 was timely for the State of
Georgia. Industrial dischargers had
installed modern water pollution control
facilities, but local governments were
encountering financial difficulties.
Therefore, the authorization of 75 percent
Federal grants by PL 92-500 would enable
local governments to proceed with programs
to install needed facilities. Also, the
Georgia program previously had concentrated
on correcting water pollution problems
related to point sources, whereas
PL 92-500 enabled the State to place
emphasis on developing a broader program
which would address all aspects of water
quality management.
Georgia's water pollution control
program is administered by the Environ-
mental Protection Division of the Depart-
ment of Natural Resources. Through the
assistance of Governor Jimmy Carter and
the Georgia Legislature, the Georgia Water
Quality Control Act was amended in 1973 to
make it consistent with PL 92-500.
Utilizing Federal funds provided to
the State under Section 106 of the Federal
Act, Georgia proceeded to modify its water
pollution control program in 1973 in order
to implement the various elements of
PL 92-500. In accordance with Title III
of the Act significant changes were made
to the State program. A continuing plan-
ning process for water quality management
was established as required by Section
303(e) of PL 92-500. The planning process
enabled the State to establish for each
river basin a priority ranking of needed
construction or improvements of waste-
water treatment works. Also, a total
maximum daily load was determined for
pollutants allowed to be discharged to
each stream segment to assure compliance
with water quality standards.
An expanded ambient water quality
monitoring and surveillance program was
developed to better identify the quality
of the State's streams. Considerable
improvements were made in the State's
ability to compile and evaluate water
quality data. Through the use of com-
puters, the information was stored and
evaluated, subsequently much of the infor-
mation was used to develop computer models
to simulate various stream reaches and the
impact of pollutional loads on the
streams.
The State's improved water quality
monitoring and data evaluation enabled
various stream reaches to be identified as
"water quality limited" or "effluent
limited". If the pollutional loads from
waste dischargers, assuming installation
of best practicable treatment (BPT) , along
a particular stream were not predicted to
sufficiently protect water quality to meet
the water quality standards for that
reach, the stream was identified as "water
quality limited" and more stringent levels
of treatment were required. If the com-
puter model predicted that installation of
BPT would allow water standards to be met,
the stream was identified as "effluent
limited" and BPT was the required level of
treatment. This more scientific approach
to the establishment of required levels of
treatment was an improvement of the State's
program and a positive impact of PL 92-500.
As previously discussed, the pro-
vision of 75 percent Federal construction
grants by PL 92-500 was an essential and
positive element of the Act. Requirements
for the preparation of a "facility plan'1
under Section 201 that would assure proper
identification of needed improvements and
the evaluation of alternatives for the
provision of the most cost-effective
system to provide these improvements was
a major positive aspect of the program.
For the first time, local governments had
assistance and support from Federal and
State governmental agencies in assuring
that their technical consultants developed
a cost-effective solution. Another major
aspect of the 201 facility plan has been
the requirement for an evaluation of
inflow-infiltration problems for publicly
owned systems. These studies have identi-
fied repairs which can be made to the
sewage collection system to reduce flows
which in turn reduce construction, opera-
tion, and maintenance costs for treatment
works.
369
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The Georgia Environmental Protection
Division has coordinated the State develop-
ed water quality plans under Section 303(e)
of the Act with the 201 facility plans
developed by local governments to identify
the level of treatment required at publicly
owned systems to protect the State's
streams. Since more than 99 percent of
the sewage from publicly owned systems in
Georgia is presently receiving biological
treatment, the emphasis on the program for
the future is to upgrade and improve exist-
ing systems and install advanced waste
treatment where needed to protect down-
stream water uses. Downstream water uses
on many of Georgia's relatively small
streams include water supply for other
communities and recreational lakes which
collect and store many of the pollutants
from upstream discharges. Therefore,
advanced waste treatment systems consist-
ing of 95 percent reduction of BOD,
reduction of phosphorus to 1.0 mg/1,
reduction of ammonia to 2.0 mg/1, the
provision of 6.0 mg/1 of dissolved oxygen
(DO) in the effluent, and disinfection
of the effluent are being required for
several systems in the northern half of
Georgia. Present studies do not verify
that these levels of treatment will cor-
rect all water quality problems; however,
it is predicted that with these levels of
treatment, present downstream water uses
can continue with reasonable assurance
that the health and welfare of the public
are protected.
A significant program authorized in
Section 109 of PL 92-500 is one for train-
ing persons in the operation and mainte-
nance of treatment works. In Georgia, a
full-time training school for operators
has been established in cooperation with
the State Department of Education. Three
full-time personnel conduct the training
school for operators of treatment works.
A wastewater treatment facility is being
constructed for training purposes at the
school. Also, an on-the-job training
program has been effectively functioning
for several years.
One of the major positive elements
of PL 92-500 is the National Pollutant
Discharge Elimination System (NPDES)
permit program established under Section
402 of the Act. Through the requirements
that each discharger obtain a permit, the
NPDES permit program has implemented the
specific effluent requirements established
for various industrial and publicly owned
systems. Georgia was approved by EPA to
administer the NPDES permit program in
early 1974 and has used it effectively to
establish schedules and conditions for
further improvements needed by certain
dischargers.
The NPDES permit program has enabled
several major accomplishments to be made.
It has been an effective enforcement tool
and the basis for substantial civil penal-
ties throughout the United States. Imple-
mentation of the NPDES permit program has
brought equity to the enforcement efforts
across the country. If a State has been
unwilling to administer a strong effective
program, then EPA has continued to conduct
the NPDES permit program. The maintenance
of a strong, consistent program has
assured various industries that have in-
stalled modern water pollution control
facilities in Georgia that their competi-
tors will do likewise in other parts of
the country. This assurance has been
extremely helpful to the States with
effective ongoing water pollution control
programs. Another major advantage of this
uniformity is the fact that an industry
proposing to locate a new plant must
install minimum treatment levels in any one
state compared to another state.
Another important and positive
aspect of the water pollution control
program under PL 92-500 has been the
emphasis on public participation as
required under Section 101(e) of the Act.
Understanding and involvement of the Public
are essential to the success of the pro-
gram. In order to maintain strong support
and commitment to the water pollution con-
trol program with the long-term substantial
levels of funding required to accomplish
the goals of the program, the citizens of
Georgia and the Nation must understand and
actively advocate it.
Georgia, along with all the other
States, is now underway with the develop-
ment of a statewide plan as required under
Section 208 of the Act. The 208 plan is
scheduled to be complete by November 1978.
As required by the Act and rules
370
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promulgated by EPA, the 208 plan will
provide Georgia with a comprehensive water
quality management plan for the future.
The 208 plan will place emphasis on non-
point source pollution as well as point
source pollution. Since a program has
already been developed under Section 303(e)
for point sources, a major effort of the
208 -program in Georgia will be to identify
the source and scope of non-point pol-
lutants. Then a program will be developed
to reduce and control non-point sources in
conjunction with point sources. It is
anticipated that completion of the 208
plan with periodic updating will result
in a management tool for the future to
assure adequate protection and management
of the State's water resources.
The 1977 status of the water quality
management program in Georgia reflects
efforts under the State's program before
and after PL 92-500. Industry in Georgia
will meet the 1977 requirements of the
Act. Several publicly owned systems will
not meet the 1977 requirements primarily
because the Federal construction grant
funds were not provided as authorized by
PL 92-500.
Since enactment of PL 92-500, almost
$250 million of Federal construction grant
funds have been obligated for improvements
to publicly owned treatment works in
Georgia. Many of these projects are now
complete or under construction. The
results of this program and the State's
earlier efforts have greatly improved
water quality in the State. In addition,
the construction grants program has
provided a positive impact on the economy
by providing jobs and an economic
stimulus during a recession period of the
economy.
As of 1977, four and one-half years
following enactment of PL 92-500, there is
considerably less water pollution in the
State of Georgia. Of the State's 32,180
kilometers (20,000 miles) of streams, less
than 1609 kilometers (1,000 miles) have
significant water pollution problems that
result in violation of water quality
standards. Perhaps of more importance is
the fact that to a great extent PL 92-500
has enabled the State to enter the third
century of our Nation better equipped,
legally and technically, to manage
effectively the water resources of the
people.
371
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FEDERAL-STATE-REGIONAL DEVELOPMENT OF A WASTEWATER
MANAGEMENT PLAN AND A WATER SUPPLY PLAN
J. L. Ledbetter, Division Director
H. F. Reheie, Chief, Water Quality
Environmental Protection Division
Georgia Department of Natural Resources
Atlanta, Georgia
Atlanta, Georgia is a major population center in the southeastern United States.
Since the region is located on one of the major drainage divides of the United States,
the water resources adjacent to the region are limited which results in serious water
supply and water quality control problems. In order to meet the needs of the future,
the region must plan and implement a sound water resources management program. The
Federal government, the State government, and the Atlanta Regional Commission (repre-
senting 46 local governments) have developed plans to meet the needs of the region to
the year 2000. Existing systems have been evaluated and stream studies have been con-
ducted. Twenty-four biological wastewater treatment works with a total design capacity
of 12.5 m /s (286 mgd) and the impact of the discharges on the three rivers draining the
region have been evaluated. Using the results of these studies and the population
prediction for the year 2000, it has been determined that water quality standards can
be met and the necessary water supply provided until the year 2000. In developing the
wastewater management plan, which required advanced waste treatment for all of the
region, major emphasis was placed on protecting downstream water uses, particularly
community water supply intakes and recreational lakes. Conservation of water and water
reuse are additional considerations that must be fully evaluated in the next few years.
If new technology is not developed and if water conservation is not practiced, the lack
of water may well be the controlling growth factor for the future of the region.
THE PLANS
During the past three years compre-
hensive and cooperative efforts have been
made to develop a wastewater management
plan and a water supply plan for the met-
ropolitan area of Atlanta, Georgia. An
in-depth study has been conducted by the
U. S. Environmental Protection Agency
(EPA), the U. S. Army Corps of Engineers,
the Georgia Environmental Protection Di-
vision, and the Atlanta Regional Com-
mission. The U. S. Environmental Pro-
tection Agency and the Corps of Engineers
represent the Federal role in the study.
The Georgia Environmental Protection
Division provides the State involvement
and the Atlanta Regional Commission is
the regional participant and represents 46
local governments in the Atlanta area. The
wastewater and water supply plans1'2 out-
line the various expansions and modifi-
cations required to meet the area's needs
for water supply and sewage treatment from
the mid 1970's to the year 2000.
Atlanta, Georgia is a major city in
the southeastern United States and serves
as the transportation center of the south-
east. Many large corporations maintain
regional offices in Atlanta. Also, most
Federal agencies, including the Environ-
mental Protection Agency, have regional
offices in Atlanta. Industrial operations
in the area are generally low water users;
373
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consequently, the approximate 7.80 m /s
(178 mgd) of wastewater from the region's
1.7 million population is primarily domes-
tic sewage.
THE ATLANTA REGION
The Atlanta region is located about
335 meters (1100 feet) above sea level.
Although it is not as significant or
spectacular, one of the major drainage
divides of the United States extends from
a northeasterly direction through the City
to a southwesterly direction. East of
this divide water eventually flows into
the Atlantic Ocean; whereas, the water
west of this divide flows into the States
of Florida and Alabama and into the Gulf
of Mexico. The upper portion of the South
River is formed in Atlanta on the east side
and the Flint River begins on the southern
edge of the City. The Chattahoochee River
flows to the west of the City. On all
three of the rivers downstream of the
Atlanta metropolitan area are significant
water users which include recreational
lakes and community water supply system
intakes.
The Atlanta metropolitan area with
a population of about 1.7 million is one
of the larger population centers in the
United States which is located inland
from the sea and on a relatively small
river. The Chattahoochee River flow is
regulated by the U. S. Army Corps of
Engineers' Buford Dam - Lake Lanier hydro-
electric operation located some 77.2 km
(48 miles) upstream of Atlanta. From that
77.2 km (48 miles) reach of the Chattahoo-
chee River four local governments,
including Atlanta, take water to supply
the water systems which collectively
serve one-third of Georgia's population.
This regulated stream, with fluctuating
flows caused by the upstream hydroelectric
operation compounded by significant with-
drawals by water supply intakes, had flows
in the early 1970's that dropped as low as
17.0 m3/s (600 cfs) further compounding
severe water quality problems downstream
of Atlanta. The wastewater management
plan and the water supply plan have been
developed to resolve many of the existing
problems and to provide the required
systems to meet the needs of the future.
The Atlanta region encompasses seven
counties. These seven counties extend
over 5330 square kilometers (2058 square
miles). Although the 1977 population is
approximately 1.7 million, it is predicted
that by the year 2000 approximately 3.5
million people will live in the Atlanta
region.
PRESENT STATUS OF WASTEWATER
TREATMENT FACILITIES
All wastewater treatment systems in
the Atlanta Metropolitan Area are modern
facilities. In the seven-county metro-
politan area, a total of 24 major treat-
ment facilities with design capacities
ranging f rom 0.044mJ/s to 5.26 m3/s (1.0
mgd to 120 mgd) are currently in oper-
ation. Their total capacity is 12.5 m /s
(286 mgd) and collectively they are treat-
ing a flow of 7.80 m3/s (178 mgd).
Although these systems were designed
to achieve secondary biological treatment,
many of them were designed and con-
structed prior to the establishment of
regulations by the U. S. Environmental
Protection Agency in 1973 which defined
uniform national standards for secondary
treatment. This definition requires that
all municipal wastewater treatment facili-
ties achieve at least 85 percent removal
of influent BODc and suspended solids, and
produce effluent quality with BOD^ and
suspended solids concentrations not exceed-
ing 30 mg/1 each, with effluent pH in the
range of 6-9 standard units, and fecal
coliform not exceeding a geometric mean of
200/100 ml. All of the treatment facili-
ties in the Metropolitan Area provide
biological treatment, but some of these
facilities do not achieve the secondary
treatment limitations.
Conditions which prevent the con-
sistent achievement of secondary treatment
standards are inadequate operator training,
staffing, and maintenance of facilities;
solids handling; presence of industrial
wastewaters; and infiltration, inflow, and
combined sewers.
Most local government officials in
Georgia understand the importance of having
sewer systems and wastewater treatment
374
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facilities in their communities, but many
do not understand the importance of oper-
ation and maintenance for those facilities.
Thus the budgets for plant maintenance and
salaries for operators are often low.
Hiring and retaining qualified operators,
then training and motivating them to get
optimum efficiency from the treatment works
they operate, are significant problems
which are being resolved very slowly.
Solids handling is a problem which
plagues a few Metropolitan Atlanta treat-
ment facilities. Two facilities have an-
aerobic digesters which ceased to function
in recent years due to long-term accumula-
tions of grease, grit and heavy metals
from industries, with the only solution to
empty the digesters and place their con-
tents in lagoons or landfills. In early
1977 the first and third largest treatment
facilities, which incinerate a mixture of
undigested and digested dewatered sludge,
had their natural gas fuel supplies inter-
rupted due to a national gas shortage in
critically cold weather. The partially
treated sludge had to be landfilled until
natural gas service was restored. The
largest metropolitan facility operated
poorly during most of 1976 since several
of its primary settling tanks were out of
service during construction, causing sig-
nificant solids losses.
Industrial wastes which enter the
sewer systems without adequate pretreat-
ment cause upsets of biological treatment
processes. All local governments have un-
dertaken programs to identify industrial
contributors and determine their waste-
water characteristics. These programs
will eventually lead to the necessary pre-
treatment or the elimination of incompati-
ble wastes.
Sewer systems in the suburban areas
surrounding the City of Atlanta are rela-
tively new and generally do not have se-
vere problems with infiltration and in-
flow. However, most engineering studies
completed recently have shown that prob-
lems with infiltration/inflow exist in
some portions of every sewage treatment
plant service area. Certain portions of
the City of Atlanta are served by combined
storm and sanitary sewers, some of which
were built as many as seventy years ago.
There are four combined sewer overflow
points in the South River Basin3. Federal
construction grants are being offered to
assist local governments in rehabilitating
sewers which have excessive infiltration
and inflow. In the South River Basin,
grants will be made available to provide
secondary treatment for combined sewer
overflows resulting from rainfalls of up
to 1.8 cm (0.7 in).
Table 1 is a compilation of relevant
information on existing treatment works
with capacities exceeding 0.22 m /s (5
mgd), and Table 2 lists some average
influent and effluent wastewater charac-
teristics for these facilities for 1976.
WATER QUALITY MANAGEMENT PLANS
Section 303(e) of the Federal Water
Pollution Control Act of 1972 requires all
states to develop comprehensive water
quality management plans for each major
river basin. These documents must contain
inventories of all point wastewater
sources, assessments of the effects of
those pollution sources on the quality of
receiving waters, and waste load allo-
cations for each pollution source. This
information is then used to develop
effluent limitations for discharges and to
establish priorities for pollution abate-
ment efforts.
Prior to the passage of Public Law
92-500, the State of Georgia had already
begun the function of water quality
management planning. Programs undertaken
by the State began with'documentation of
serious water pollution problems in the
three stream systems receiving the most
wastewater in the Atlanta Metropolitan
Area: the Chattahoochee, Flint and South
Rivers. Following this documentation,
the State undertook programs to measure
certain physical, chemical, and biological
characteristics of the streams so that
mathematical models for certain water
quality parameters could be developed.
Dissolved oxygen depletion was considered
to be the most serious water quality
problem in all three of these streams.
All three streams had organic and nitroge-
nous waste loads sufficiently high to
cause septic conditions during periods of
warm weather and low stream flows, even
with good stream reaeration character-
istics.
375
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TABLE 1. SYSTEM DESCRIPTION - MAJOR TREATMENT WORKS
ATLANTA, GEORGIA METROPOLITAN AREA
Facility
Flint River WPCP #1
Flint River WPCP #2
South River WPCP
Intrenchment Creek WPCP
Snapfinger WPCP
Big Creek WPCP
Chattahoochee WPCP
Clayton WPCP
Utoy Creek WPCP
South Cobb WPCP
Camp Creek WPCP
Type of
Treatment
AS
AS & TF
AS & TF
TF
AS & TF
AS
AS
AS
AS
AS
AS
Treatment
mgd
6
9
18
20
22
6
10
120
30
8
15
Capacity
0.26
0.39
0.79
0.88
0.96
0.26
0.44
5.26
1.31
0.35
0.66
Type of
Sewer
System
SEP
SEP
COM
COM
SEP
SEP
SEP
COM
COM
SEP
SEP
Receiving
River
Flint
Flint
South
South
South
Chattahoochee
Chattahoochee
Chattahoochee
Chattahoochee
Chattahoochee
Chattahoochee
ABBREVIATIONS: WPCP - Water Pollution Control Plant
AS - Activated Sludge
TF - Trickling Filter
SEP - Separated Sanitary Sewers
COM - Combined Storm & Sanitary Sewers
376
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TABLE 2. 1976 AVERAGE PERFORMANCE - MAJOR WASTEWATER TREATMENT WORKS
ATLANTA, GEORGIA METROPOLITAN AREA
WPCP Facility Name
Flint River #1
Flint River #2
South River
Intrenchment
Snapfinger
Big Creek
Chattahoochee
Clayton
Utoy Creek
South Cobb
Camp Creek
Treated Flow
mgd m3/s
2
8
14
12
15
2
9
79
13
8
4
.5
.3
.3
.4
.0
.8
.9
.7
.7
.3
.4
0.
0.
0.
0.
0.
0.
0.
3.
0.
0.
0.
11
36
63
54
66
12
43
49
60
36
19
Inf.
BOD5
mg/1
194
202
210
202
184
120
238
146
150
153
95
Eff.
BOD5
mg/1
34
43
27
35
26
11
63
41
23
40
22
Inf.
SS
mg/1
140
330
149
122
194
124
460
171
177
143
119
Eff.
SS
mg/1
34
94
47
30
20
9
114
74
42
48
28
Eff.
PH
SU
7
7
7
6
6
6
6
6
7
6
6
.2
.6
.3
.9
.8
.7
.8
.6
.0
.4
.5
Effluent
Fecal
Colif orm
No./lOO ml
420
75
230,000
1,400,000
60
4
76
790,000
540
140
ABBREVIATIONS: Inf.
Eff.
SS
SU
- Influent
- Effluent
- Suspended Solids
- Standard Units
377
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The radiotracer technique developed
by Tsivoglou^, which is the only direct
measurement of reaeration in natural
streams, was used in the model development
on all three of these rivers. The tech-
nique5uses three tracers simultaneously:
krypton-85, as a dissolved gas, is the
tracer for dissolved oxygen; tritium, as
water molecules, is the tracer for dis-
persion; and rhodamine - WT fluorescent
dye provides information on time of flow.
The ratio of relative gas transfer capa-
bilities of krypton and oxygen, measured
as their respective reaeration coef-
ficients, is 0.83, with krypton transfer
being the slower process. By measuring
of the loss of the krypton tracer to the
atmosphere and accounting for in-stream
dispersion, a direct correlation to oxygen
transfer is obtained.
The mathematical model used for each
stream was a modified Streeter-Phelps
equation which accounted for reaeration,
carbonaceous oxygen demand, nitrogenous
oxygen demand, and benthic oxygen demand.
The model was steady-state and one-
dimensional. The model for each stream
was calibrated to verify measured field
data and was then used to predict the
responses of the stream under future con-
ditions of wastewater flows and treatment
levels. Computer programs were used to
test a wide variety of alternatives in
each of the models.
Uniform effluent limits were
established for all major wastewater dis-
charges in the Flint River and the South
River Basins. The effluent limitations
were: BODr not to exceed 10 mg/1, ammonia
nitrogen not to exceed 2 mg/1, total phos-
phorus not to exceed 1 mg/1, and dissolved
oxygen not less than 6 mg/1. The phos-
phorus limitation was established for
treatment works in the South River Basin
to reduce eutrophication of a popular
recreational lake some 64 km (40 miles)
downstream. The phosphorus limitation was
imposed on treatment works in the Flint
River Basin so that reasonably high treat-
ment would be applied to upgrade the
quality of the Flint River which is used
for water supply downstream from the
Atlanta Metropolitan Area.
Both the Flint River and the South
River are unregulated streams and are
quite small, with their headwaters
rising in the Metropolitan Area. The
Chattahoochee River, however, with a
drainage area of 3760 sq. km. (1450 sq.
mi.) at Atlanta is a highly regulated
stream due to the generation of hydro-
electric power upstream from the Metro-
politan Area. The Chattahoochee River
receives wastewater discharges from the
sewer systems of three county govern-
ments and the City of Atlanta. In
addition to its widely fluctuating flow
regime, the Chattahoochee River has sig-
nificant withdrawals for local water
supplies and is used as once-through
cooling water for two major steam electric
generating plants which serve the area.
Taking into account the effects of all of
these conditions, the State again con-
structed mathematical water quality models
of the Chattahoochee River and determined
that a minimum of 21.2 m3/s (750 cfs) of
water would be needed in the Chattahoochee
River just downstream from the City of
Atlanta's water supply pumping station in
order to maintain an acceptable stream
quality for a "fishing" classification.
In order to meet fishing standards at a
minimum flow of 21.2 m-^/s (750 cfs) on the
Chattahoochee River, it was necessary to
establish a uniform treatment level
through the mathematical modeling process
for all major dischargers, assuming a
minimum river flow of 21.2 m /s (750 cfs).
All dischargers were required to achieve
a level of treatment higher than the EPA
established secondary treatment standards.
The effluent quality to be met by the dis-
chargers on the Chattahoochee River is:
BODr not to exceed 17 mg/1, ammonia
nitrogen not to exceed 5 mg/1, and dis-
solved oxygen not less than 6 mg/1.
The results of the mathematical
modeling and waste load allocation
processes for these three rivers were
incorporated into the State's water
quality management plans required under
Section 303(e) of PL 92-500. These
limitations were also written into the
discharge permits for all affected treat-
ment facilities and information from these
studies was incorporated into the local
government discharge ranking system which
is used to prioritize projects for
Federal construction grants. Through the
378
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planning process, and as a result of the
important water uses downstream from the
Atlanta area in all directions, it has been
determined that every publicly owned
treatment facility, whether presently
existing or planned for the future, will
have to achieve effluent quality higher
than secondary treatment.
DETAILS OF FUTURE SYSTEMS
Solutions to meeting the necessary
water quality standards and complying with
the effluent limitations established by
the State have been developed by several
of the major dischargers through the
facilities planning process of the Federal
construction grant program. Facilities
planning, as required by Section 201 of
PL 92-500, has not been completed for all
sewer service areas within the Atlanta
Metropolitan Area, but a considerable
portion of such planning has been done.
The trend in the metropolitan area is
toward construction of large regional
treatment works with extensive service
areas, since these systems offer signifi-
cant economies of scale. A variety of
technical solutions to meet the required
effluent limitations has been developed by
consulting engineers retained by the local
governments.
Two treatment facilities discharging
to the Chattahoochee River will be the
first to be upgraded and expanded in the
Atlanta area.. The Chattahoochee Water
Pollution Control Plant (WPCP), which
receives wastewater from two cities, and
unincorporated areas of two counties, has
an expansion from 0.44 m /s (10 mgd) to
0.88 m-'/s (20 mgd) under construction.
The facility, which currently utilizes
a conventional activated sludge process
and anaerobic sludge digestion, will
convert its aerobic digesters to addition-
al activated sludge basins. Plastic media
nitrification towers with pH adjustment
capability will be added to reduce ammonia
concentrations following the activated
sludge process. Expected final effluent
quality is: BODc not exceeding 17 mg/1,
NH-^N) not exceeding 5 mg/1, and suspended
solids not exceeding 30 mg/1. Sludge will
be anaerobically digested and dewatered in
filter presses, with the filter cake being
incinerated. The incinerator will be
fueled by digester gases.
The South Cobb WPCP, which treats
wastewater from five cities and portions
of two counties, will be expanded from
0.35 m3/s (8 mgd) to 1.05 m3/s (24 mgd).
The existing conventional activated sludge
system will be expanded and converted to
use pure oxygen aeration, combining carbo-
naceous removal and nitrification in one
process. Pure oxygen gas will be gener-
ated by a 2900 kg/day (32 ton/day) cryo-
genic plant, and liquid oxygen storage
will provide a backup supply. The South
Cobb WPCP will meet the same final efflu-
ent limits as the Chattahoochee WPCP.
Undigested sludge will be gravity thicken-
ed, heat dried in rotating kilns,
pelletized and bagged for use as a fertil-
izer and soil conditioner.
All wastewater currently being dis-
charged to the Flint River will be
removed. Effluents from the Flint River
WPCP #2 and a smaller facility nearby will
be disposed on land by spray irrigation.
The effluents from the Flint River WPCP #1
and another smaller facility will be
pumped with effluent from two facilities
in the South River Basin to the
Chattahoochee River. These actions will
be particularly beneficial since the Flint
River Basin is the most severely water
quality limited and the smallest of all
of the major drainage basins in the
Metropolitan Area.
Engineering analysis showed that it
would be more cost-effective (cost-ef-
fectiveness is determined by comparing the
present worth of treatment alternatives)
to construct a land application system
than to provide the advanced levels of
treatment required for stream discharge.
The Flint River WPCP #2 will be expanded
to provide secondary treatment for future
population needs and the effluent will be
sprayed onto an area of land which is
tributary to the surface water supply of
the same authority which owns this plant.
Thus, this local government, which is
predicted to have future water shortages,
will actually be recycling a large
portion of its wastewater, since approxi-
mately 90 percent of the water which falls
onto the spray fields will ultimately find
its way back into surface streams through
groundwater channels. The authority will
also grow trees in the land application
379
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area which will be harvested and sold to
pulp and paper companies. The project will
consist of pumping an average of 0.85 m /s
(19.5 mgd) of wastewater which has
received conventional secondary treatment
to a storage reservoir which will have
sufficient volume to store 12 days of
waste flow. The water will then be pumped
onto wooded areas of sandy clay soil
through a sprinkler distribution system
approximately 488,000 m (1,600,000 ft.) in
length. The year-round application rate
will average 6.35 cm (2.5 in.) per week
and the total wetted area of land will be
approximately 955 ha (2360 acres). The
authority will have to acquire approxi-
mately 1420 ha (3500 acres) of land to
allow adequate buffer areas around exist-
ing homes and roads.
In the South River Basin, the
largest existing facility is the
Snapfinger WPCP which will be upgraded and
expanded to 1.58 m /s (36 mgd) to meet
future population needs, and will con-
tinue to discharge to the South River. To
meet the required effluent limits of BOD5
= 10 mg/1, NHo(N) = 2 mg/1 and total phos-
phorus = 1 mg/1, the facility will employ
the following processes: chemical
precipitation in primary clarifiers using
lime for removal of organic materials;
aeration basins for biological nitrifi-
cation to remove ammonia; post-chemical
precipitation for phosphorus removal; and
dual-media filtration for suspended
solids removal. Post-chemical sludge will
be classified by centrifuges, recalcined,
and reused. Primary and nitrification
sludges will be filter pressed, with the
filter cake being incinerated.
The City of Atlanta, largest local
government in the metropolitan area, has
wastewater treatment facilities in the
Flint River, South River, and the
Chattahoochee River Basins. Faced with
providing advanced wastewater treatment
(effluent limits identical to those from
the Snapfinger WPCP) for its South River,
Flint River #1, and Intrenchment Creek
WPCP's, Atlanta selected a plan which will
divert the effluents of those facilities
a distance of some 16.1 km (10 mi.)
through underground tunnels, back to the
Chattahoochee River from which the water
originated. In doing this, Atlanta has
the advantage of providing a lower level
of treatment (BOD5 = 15 mg/1, NH3(N) =
4 mg/1, and no limit on phosphorus) for
these effluents than it would have if it
had left them in the Flint and South
Rivers. The City will have substantial
economic benefits by reducing the annual
operating costs below those which would be
required for operating more advanced
treatment systems. In addition, the Three
Rivers proposal will provide retention and
partial treatment for wastewater from
three combined sewer overflows in the
South River Basin.
All owners of wastewater treatment
and collection systems in the Atlanta
Metropolitan Area, other than those
discussed in the preceding paragraphs, are
in various stages of detailed planning to
determine what actions may be necessary to
meet future needs and to comply with
effluent limits established through the
State's planning processes. Availability
of grants from the U. S. Environmental
Protection Agency to pay for 75 percent of
the costs of planning, design, and con-
struction assures the continued interest
and cooperation of the local governments
in these programs.
REGIONAL-AREAWIDE WASTEWATER
MANAGEMENT PLAN
The Atlanta Regional Commission(ARC)
is the regional planning and intergovern-
mental coordinating agency for 46 local
governments in the Atlanta Metropolitan
Area, The Commission has a full-time
technical staff which has the responsi-
bility for preparing regional plans for
transportation, land use, health, social
services, water supply, and wastewater
management. However, ARC does not have
the authority or responsibility to
implement the plans. The 46 local govern-
ments must implement various plans
developed by ARC; however, the intergovern-
mental cooperation that is essential to
the implementation of a plan is often
accomplished through ARC.
Recognizing the complexities of
wastewater management and the fact that
natural drainage areas often cross several
local government boundaries, the ARC
requested assistance from the Federal and
380
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State governments in the development of
a comprehensive plan. In 1973 the joint
effort was initiated. While the ARC's
technical staff emphasized coordination of
local governments within the region and
the solution of their problems, the Feder-
al and State agencies placed emphasis on
evaluating the impact of ARC's wastewater
and water supply plans on areas outside
the region.
The Federal agencies (EFA and Corps
of Engineers) conducted portions of the
study that produced statistical data to
guide the selection of the most cost-
effective alternatives. An in-depth
evaluation of the stream flows of the
area was made and predictions for minimum
flows were developed. The State conducted
stream studies to verify existing water
quality and through computer modeling
determined allowable waste loads. Utiliz-
ing the construction grant funds provided
to the State under Section 201 of
PL 92-500, the State has worked with the
local governments to initiate imple-
mentation of the recommended modifications
and improvements to the publicly owned
treatment works in the region.
During 1976 and in accordance with
Section 208 of PL 92-500, the State
designated the region served by ARC for
the development of an areawide wastewater
management plan and designated ARC as the
agency to develop the plan. Many of the
improvements needed in the region's system
of point wastewater sources have begun to
be implemented as a result of State
requirements and the regional study con-
ducted between 1973 and 1976. Efforts
under the 208 study will concentrate on
development of a plan to control or
minimize non-point source pollution.
Pollution from urban runoff, which
includes soil-erosion, sewage from com-
bined sewers, storm drainage from
commercial districts, infiltration and
inflow to sanitary sewers, and debris from
the streets, will be studied. Alterna-
tives will then be recommended to reduce
non-point source pollutants. Preliminary
studies indicate the non-point source
pollutants contribute as much as 50 per-
cent of the pollutional load to the
streams in Atlanta region during periods
of high rainfall. Since the existing
point sources receive biological treatment
already, the additional reduction from
point sources will be small and very
expensive which makes it imperative that
the 208 study produce cost-effective
alternatives to reduce and control non-
point source pollution.
WATER SUPPLY PLAN
An adequate and dependable water
supply for any community is essential for
the health, safety, and economic well-being
of the region. In the Atlanta region the
geological formations are such that
groundwater is unavailable. Therefore,
the region is dependent on surface waters
as a source for water supply. The
drainage divide through the Atlanta
region, with the Chattahoochee River being
the only river which flows through the
region, further limits available water.
The necessity of maintaining a minimum
streamflow past Atlanta for the
assimilation of treated wastewater from
the region further reduces the available
supply.
With the projected population of
3.5 million by the year 2000 and the
established minimum flow for assimilation
of treated wastewater of 21.2 m^/s (750
cfs), the development of a plan to provide
for realistic alternatives to meet the
water needs of the region had become
critical by the mid 1970's. Since the
Chattahoochee River has a hydroelectric
facility about 77.2 km (48 miles) above
Atlanta, an evaluation was made of the
reservoir to determine the maximum
sustained yield that could be provided
during drought conditions. The maximum
sustained yield for a drought condition
comparable to the most severe drought of
record was determined to be 51.0 m /s
(1800 cfs). In order for the region's
peak day demand by the year 2000 of
29.7 m3/s (1050 cfs) to be met under
drought conditions, two alternatives have
been identified as realistic. One
alternative is to construct a smaller re-
regulation dam about 9.65 km (6.0 mi.)
downstream of the existing hydroelectric
facility. A second alternative is to
modify the operation of the existing
hydroelectric facility to provide a
constant flow of at least 51.0m3/s
381
-------
(1800 cfs) at all times. Both of these
alternatives are presently under further
economic and environmental study. In the
meantime, a slight modification in the
operation of the hydroelectric facility
has assured the region of the needed water
until the 1985-1987 period.
FEDERAL-STATE-REGIONAL EFFORTS
The comprehensive three year effort
by Federal, State, and Regional agencies
has produced implementable plans for
management of wastewater and water supply
systems for the Atlanta region through the
year 2000. Local governments in the
region must now implement the plans under
the guidance of the State and with the
assistance of ARC. Local governments must
begin requiring conservation of water
through education of their citizens and
establishment of new plumbing codes. The
Federal agencies must continue to
participate in these efforts to assure an
adequate water supply to the region and
an approvable non-point source pollution
control strategy. In the final analysis,
it has been determined that the water
resources of the Atlanta region may be
the controlling or limiting factor for the
region's future instead of energy or other
resources.
5. Tsivoglou, E. C., and Wallace, J. R.,
"Characterization of Stream Reaeration
Capacity", EPA-R3-72-012. EPA,
Washington, D.C. (1972).
REFERENCES
1. "Atlanta Region Areawide Wastewater
Management Plan", Metropolitan Atlanta
Water Resources Study, Atlanta Region-
al Commission (1976).
2. "Water Supply Plan for the Atlanta
Region", Metropolitan Atlanta Water
Water Resources Study, Atlanta Region-
al Commission (1976).
3. "Storm and Combined Sewer Pollution
Sources and Abatement", U. S.
Environmental Protection Agency,
Atlanta, Georgia (1971).
4. Tsivoglou, E.G., and Neal, L.A. ,
"Tracer Measurement of Reaeration:
III. Predicting the Reaeration
Capacity of Inland Streams." Jour.
Water Poll. Control Fed., 48, 2669
(1976).
382
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REGIONAL SOLUTIONS TO
DOMESTIC WASTEWATER MANAGEMENT
R. S. Burd
U.S. Environmental Protection Agency, Region X
1200 Sixth Avenue
Seattle, Washington 98101 U.S.A.
ABSTRACT
Regional solutions to wastewater collection and treatment are discussed in terms of
encouraging their adoption. Problems encountered in implementing regionalization are
identified as are the many advantages that can be gained if these problems are overcome.
A number of important issues that should be considered in any regionalization effort are
discussed.
INTRODUCTION
The creation of regional agencies to
collect and treat wastewater is usually a
difficult and painful process. There are
many reasons for this-but-the following are
among those most frequently encountered.
Existing wastewater collection and treat-
ment jurisdictions are very reluctant to
give up their responsibilities-and-if they
do, often maintain bitterness over lost
responsibilities for a long period of time.
And, a new regional agency inherits all of
the politically based hostilities of its
constituencies. If these and other problems
can be overcome, there can be real advant-
ages to regionalizing wastewater management
systems.
BACKGROUND
Much of the time regional solutions to
regional problems are defended on the basis
of their value to protecting the environ-
ment. This is because a large number of
environmental concerns do not respect the
artificial boundaries of cities and counties
as such; they must be attacked regionally
on the basis of river basins or air sheds
for example. However, the most compelling
arguments on behalf of regional wastewater
management may be economic and political
rather than environmental.
Regionalization in the wastewater field
is not new. There are many agencies in
large urban areas of the U.S.A. as well as
Europe that have long histories in water
pollution control. Recent Federal legisla-
tion has encouraged regionalism by promoting
the development of regional waste management
plans and by encouraging the most cost-
effective solution to wastewater collection
and treatment.
Concerning the latter, it just didn't
seem economical to have two wastewater
treatment plants, perhaps even across the
street from one another, separated by
jurisdictional boundaries. Historically,
most large urban areas of the U.S.A. had
many—many highly independent political
jurisdictions. Over the years some pro-
gress was made in waste management through
the formation of semi-autonomous sewer dis-
tricts throughout an area. Further, inter-
community sewerage agreements were started
between a number of area communities in
particular urban centers. But, while these
steps represented some improvement, many
problems remained.
REGIONALIZATION CONSIDERATIONS
A successful regional wastewater man-
agement agency usually has the following
characteristics:
1. The agency fills a clearly defined
and recognized need.
383
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2. There is a strong personal commit-
ment to regionalization on the part of the
elected officials and key members of insti-
tutions that are involved.
3. A sound financing program exists
which is equitable for all users.
There are two major concepts of region-
al ization. The first concept is one where
the regional agency acts as a wholesaler of
services to existing jurisdictions. These
jurisdictions then continue to deal with
the public on a "retail" level. The second
concept is a complete consolidation, wherein
the regional agency provides the service
and deals with the public as a customer.
In creating a wholesale/retail concept of
regionalization, one of the more difficult
aspects is to determine which resources be-
long to the regional agency and which to the
surviving local jurisdictions.
A most important consideration is that of
properly structuring the governing Board
or Commission to manage the agency. The
governing body should be responsive to the
public if the agency has taxing authority
then it may need equal representation, i.e.
"one man, one vote". If the smallest
jurisdiction in a regional authority has
one vote, then the larger jurisdictions
must have a proportionately larger vote.
Financial considerations leading to
regionalization decisions include a look
at the status of each agency in terms of
whether they will benefit from regional
service and a look at the equity each may
have in the present sewers and treatment
plants. Future funding for regional
agencies eases financial problems because
the Federal and State governments providing
grants can deal with one entity. It avoids
the technical and political problems of
trying to resolve conflicts between dif-
ferent agencies not wanting to become part
of a regional system.
But, at EPA, if we think a regional
system is the cost-effective way of pro-
viding wastewater collection and treatment
of domestice waste we use economic incentives
to force the issue. That is, we refuse to
award the 75% construction grant if the
political jurisdictions don't get together.
Or, if a city was awarded a grant on the
basis it would serve as a regional facility--
and then--it refuses to accept another
cities waste for political reasons (such
as insisting on annexation first), we refuse
to make payments on the grant or to award
future grants. These financial incentives
plus an incentive often used by State
governements—a ban on new connections to
existing sewers—usually forces a favorable
regionalization decision.
Another problem to consider in region-
alization decisions is one of people.
Preserving the identity of workers, managers
and public board members who represent
agencies that are affected by regional
plans is important. It is often good
practice to accept existing staff and
retrain them if necessary.
ADVANTAGES
There are a number of advantages
possible with regional wastewater manage-
ment systems. First, there are economies
of scale, both for the capital investment
and for the operation and maintenance
expenses. Also, cities may be able to
transfer their debt for capital costs to
a regional authority where it can be handled
easier.
There are water quality advantages to
regional system. It can eliminate multiple
discharges that are at the wrong point
and are causing water pollution. Regionali-
zation can provide more flexibility in
treatment plant operation and—being a
larger system—probably can support a
budget for better operation and maintenance.
Consolidation of technical and financial
resources could allow for problem solving;
i.e. some RSD work. Finally, there is a
likelihood that the growth and development
of an urban area will be more orderly than
if small individual jurisdictions were pro-
viding sewerage service.
In summary, forming regional wastewater
management systems can be cost—effective,
provide for compliance with water quality
standards, and it can provide a high level
of political and managerial experience
and accountability.
384
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URBAN RUNOFF POLLUTION CONTROL TECHNOLOGY OVERVIEW
C.
R.
H.
A.
B.
I.
E.
N.
Brunner
Field
Masters
Tafuri
Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
ABSTRACT
This Overview describes the major elements of the Urban Runoff Pollution Control
Program. Problem Definition, User Assistance Tools, Management Alternatives and
Technology Transfer are covered, including some of the highlights of the Program's
future direction and products from over 150 of its research projects. References are
cited for completed Program reports, ongoing Program projects, and in-house documents.
Capital cost comparisons for storm and combined sewer control/treatment are given, along
with a specific example of cost-effective solution for urban runoff pollution control by
in-line storage in Seattle. In a study done in Des Moines, using a simplified receiving
water model, four control alternatives were compared, considering cost and effectiveness
in terms of a frequency of D.O. standard violations.
INTRODUCTION
Control and treatment of stormwater
discharges and combined sewage overflows
from urban areas are problems of increas-
ing importance in the field of water
quality management. Over the past decade
much research effort has been expended and
a large amount of data has been generated,
primarily through the actions and support
of the U.S. Environmental Protection
Agency's Storm and Combined Sewer Research
and Development Program.
The products of the Program (Figure
1) are divided into the following areas,
common to the major elements of Combined
Sewer Overflow Pollution Control, and
Sewered and Unsewered Runoff Pollution
Control: Problem Definition, User
Assistance Tools (Instrumentation,
Computers) , Land Management, Collection
System Control, Storage, Treatment, Sludge
and Solids, Integrated Systems, and
Technical Assistance and Technology Transfer.
Table 1 breaks down these categories
into more specific elements. There have
been about 150 projects under the Program.
References are cited for completed Program
reports (numerically indicated), ongoing
Program projects (indicated by "P" numbers),
and in-house and miscellaneous documents
(indicated by "R" numbers).
PROBLEM DEFINITION
The program starts with "Problem
Definition" broken into "Characterization"
and "Solution Methodology" (Figure 2).
The background of sewer construction
led to the present urban runoff problem.
Early drainage plans made no provisions for
storm flow pollutional impacts. Untreated
overflows occur from storm events giving
rise to the storm flow pollution problem.
Simply stated the problem is:
385
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COMBINED
SEWERS
INFILTRATED
SAN. SEWERS
I
STORM
SEWERS
I
UNSEWERED
RUNOFF
HYDROLOGIC j
MODIFICATIONS'
COMBINED SEWER
POLLUTION CONTROL
SEWERED & UNSEWERED
RUNOFF
POLLUTION CONTROL
RUNOFF POLLUTION
CONTROL PROGRAM
•PROBLEM DEFINITION
• USER ASSISTANCE TOOLS
INSTR. & COMPUTERS
•LAND MANAGEMENT
•COLL. SYS. CONTROL
• STORAGE
• TREATMENT
• SLUDGE/SOLIDS
• INTEGRATED SYSTEMS
• TECHNOLOGY TRANSFER
Figure 1. EPA Storm and Combined Sewer R&D Program
-------
CATEGORIES
PROBLEM UIUHM1QN
Characterization
Solution Methodology
USER ASSISTANCE TOOLS
Instrumentation
Simulation Models
LAND MANAGEMENT
Enforced controls
Neighborhood sanitation
COLLECTION SYSTEM CONTROLS
Sewer separation
Sewers
tide gates
Remote monitoring with
STORAGE
In-Line
("REATMENT
Biological treatment
Physical-chemical
Disinfection
Land disposal
SLUDfcEVSULfDS
Characterization/Quanti-
fication
Treatment handling schemes
Caries)
Storage/treatment
Dual use WUF/DWF (storage/
treatment
fECHNICAL ASSISTANCE AND
TECHNOLOGY TRANSFER'
Consultation to Fed. .
quasl-govt. agencies
Public Inf. Requests
Consultation to foreign
govtt and International
confer.
In-House seminars
5WMM
Higher Education
Planning/design/SOTV
assess manuals and extra-
mural publications
INITIATED/ ACCOMPLISHED
Prelim, appraisal s CSO/SU prob. . CSO/SW char. .
deicing, sed./eros., loading factors, rec. water
SOTA 5i« tech., plan/select guide, conduct of SU
studies, SOTA's sed./eros. S deicing control, unit
Raingage, flow measuring, sampling, monitoring,
control
Simplified, detailed/complex, operational.
NON-STRUCTURAL:
tural), porous pavement
Air pollution, eros./sed., cropping, berms, chemical
Street cleaning, solid waste management
May require separate treatment system
"First flush" relief: flushing/cleaning, new designs
{low flow carrying vel . and added storage), I/I pre-
vent and control (with manuals), polymers to In-
crease capacity
swirl & helical, fluidic reg.
Provides storage/discharge options
tunnels), underwater, solids impacts
Contact stabilization, trickling filters, lagoons,
w/continuously operated plant
Precipitation, filtration, adsorption, ion exchange,
break-pt Cl?
dioxide, on-slte gen., high-rate, mixing, micro-
organism indicator study (pathogen, virjs), 2-stage
Marsh land
Classification requirement, treatabil i ty, vital
On-site vs DWF tnnt.. land disposal
tion, incineration
Pump-back, sed. In storage, disinfection, break-even
econ. w/treatment
Lagoon storage/treat., HRTF, contact stab., P-C, hi-
rate filter, equalization, combined sewers
treat. /reuse
EPA, OAWP (needs surveys): EPA TT (seminars, film
EPA Hq and Regions on 201/208 studies and seminars;
Reg. V on 108 grants; NSF, DOT, OURT (reviews,
and rept reviews, joint nat'l assess, projects)
ports, example methodology for prob. solution, conf.
moderator, prog, committees
TT (France, Japan, Denmark, Norway, Sweden, Canada,
Netherlands, Australia, New Zealand); Canadian (TAG)
IJC (steering com.) IAUPR (confer. & prog, commit-
tees); various conferences and publications
Varioi/s tech. areas; overviews
Short course,; user's assistance manuals/dissem-
ination
SCS prog, university course man.
Overall prog, concepts, sol. method, sampling/anal.,
costs, specific processes
ONGOING
-Direct rec. water/source loading factor analys.s
-Dev. SSCS strategy document
-Analyze optimum SSCS/DWF T/C combinations
-Verif. magnetic flowmeter for simultaneous press/
gravity flow meas. (supplement)
-Demo in-situ TOC anal. 4 storm flow sampler
-Dev. syst. analysts program for quantification/hand-
ling of CSO sludge/solids
-Oev. autom. oper. model for real-time control w/raln
fall predict.
stream det./ret.
-Demo in-situ hydrophobic substance
-Demo sed./eros . control techniques in SE USA
(suppl ement)
-Demo periodic sewer flushing. CSO 1st flush relief
concrete pipe
-Dev. autom. operational model for real-time control
w/rainfal 1 predict.
high-rate disinf by CKWClj, and mixing incl:
resid. toxic/carcinogenic Cl-j comp. viral disinf.
-Feas. of land disposal (Envirex-supplement)
-Evaluate: methods of ultimate disposal of WWF solids
and impacts of WWF sludges/solids on DWF plant
(Envirex-supplement)
-Continuous (IBS - 20% of prog, time)
(201) and planning grant (208) assist.
due to CSO emphasis
Table 1. Summary Storm and Combined Sewer Program
387
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PRE-FY76
FY76
FUTURE
00
00
CHARACTERIZATION
•PRELIM APPRAISALS CSO/SW PROS
•CSO/SW CHARACTERIZATION
-FLOW
-LAND LOADING FACTORS(D/D ACCUMUL
-POLLUTANT CONCENTRATIONS
•REC. WATER IMPACT PREDICTIONS
•DEICING CHEMICALS
• SEDIMENT/EROSION
•PATHOGEN ANALYSIS
• NATIONWIDE CONTROL/COST ASSESS
•DATA BASE
DIRECT REC. WATER/SOURCE
LDG. ANAL
ADDITIONAL REC. WATER/
OPTIMIZED SOURCE LDG FACTORS
SOLUTION METHODOLOGY
• SOTA'S FLOW MEAS
-FLOWRATE
-SAMPLING/IN SITU ORG
• SOTA DEICING CONTROL
• SOTA SEDIM/EROSION CONTROL
•8-CITIES ECON./SOLUTION COMPARISONS
• SOTA S&CS TECHNOLOGY AND FILM
•MANUAL: STORM FLOW RATE &
VOL DETERMINATION
•GUIDE FOR CONDUCT OF SW STUDIES
• PROCESS COST FACTOR DEV
•GUIDE FOR URBAN PLAN/COR RECTI ON;
INCLUDE REC. WATER OBJECTIVES
• CITY-WIDE DEM.
DEV S&CS STRATEGY DOC
(IN-HOUSE)
ANALYZE OPT. S&CS/DWF
T/C COMB. (IN-HOUSE)
MANUAL: REFINED SOLUTION
METHODOLOGY
NAT'L ASSESS PLAN GRANTS
Figure 2. Problem Definition
-------
200
200
BOD
SS
\ COMBINED
I I STORM
6-7
DO
5*107
H| RAW
¥77\ COMBINED
I I STORM
10
TOTAL COLIFORM TOTAL
MPN/100 ml NITROGEN
TOTAL
PHOSPHORUS
Figure 3. Representative Strengths of
Wastewaters (Flow Weighted
Means in mg/1)
389
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"When a city takes a bath, what
do you do with the dirty water?"
Four types of discharges are involved:
combined sewer overflows (CSO), storm
drainage in separate systems, overflows
from infiltrated sanitary sewers and
unsewered runoff. Because of the inability
to control the latter, it is usually for-
gotten. Significantly, the storm path
and collection system configuration may
have a pronounced influence on combined
overflow quality, resulting in simultaneous
discharge mixtures of sewage and runoff at
different points, varying from raw to
highly diluted as the system adjusts to a
particular storm pattern. The problem
constituents of general concern are
visible matter, infectious bacteria,
organics, and solids and in addition may
include nutrients, heavy metals and
pesticides.
Characterization
Representative Concentrations
Figure 3 gives some representative
concentrations for comparison purposes.
As shown the average BOD concentration in
combined sewer overflow is approximately
one-half the raw sanitary sewage BOD.
However, storm discharges must be
considered in terms of their shockloading
effect due to their great magnitude. A
not uncommon rainfall intensity of 1 in./
hr. will produce urban flowrates 50 to
100 times greater than the dry-weather
flow (DWF) from the same area. Even
separate storm wastewaters are significant
sources of pollution, "typically" charac-
terized as having solids concentrations
equal to or greater than those of untreated
sanitary wastewater, and BOD concentrations
approximately equal to those of secondary
effluent. Bacterial contamination of
separate storm wastewaters is typically
2 to 4 orders of magnitude less than that
of untreated sanitary wastewaters. Signi-
ficantly, however, it is 2 to 4 orders of
magnitude greater than concentrations
considered safe for water contact activi-
ties.
Microbiological studies of both
sanitary sewage and storm runoff have
shown a consistently high recovery of
both pathogenic and indicator organisms
(160). The most concentrated pathogens
were Pseudomonas aeruginosa and Staphy-
lococcus aureus at levels ranging from
103 to 105 and from 10° to 103/100 ml,
respectively. Salmonella and entero-
viruses, though frequently isolated were
found at levels of only 10° to 104/10
liters of urban runoff. This strongly
indicates that all types of urban runoff,
in general, can be hazardous to health.
Past characterization studies for
storm flow provide a data base for
pollutant source accumulation, and
hydraulic and pollutant loads (2, 20, 34,
35, 41, 47, 51, 53, 54, 59, 60, 63, 65,
67, 73, 81, 82, 83, 88, 102, 123, 124,
127, 128, 143, 149). A computerized data
base and retrieval system has been developed
for urban runoff (P-49). The data base
contains screened and reasonably accurate
data that is intended for model verification
and future study area data synthesis —
especially useful to 201 and 208 (Section
208, PL 92-500) planning agencies.
Besides the more generalized
characterization studies, specific studies
have been carried out for deicing salt
(67, 109, 86), and sediment/erosion (129).
Representative Loads
From 40% to 80% of the total annual
organic loading entering receiving waters
from a city is caused by sources other
than the treatment plant (R-l). Assuming
treatment plants are operating properly,
during a single storm event, from 94% to
99% of the organic load and almost all
settleable solids are attributed to wet-
weather flow (WWF) sources (R-l) .
The runoff of toxic pollutants,
particularly heavy metals, is also high —
considerably higher than typical indus-
trial discharges. For example, New York
Harbor receives metals from treatment
plant effluents; discharges from combined
sewer overflows and separate storm sewers;
and untreated wastewater included in the
CSO and from sewered areas not yet served
by treatment plants. As can be seen in
Table 2, urban runoff is the major
contributor of heavy metals to the
Harbor (R-2).
Potential Impacts
Approximately one-half of the stream
miles in this country are water quality
390
-------
TABLE 2 - METALS DISCHARGED TO THE HARBOR FROM NEW YORK CITY SOURCES
SOURCE
Plant effluents
Runoff*
Untreated wastewater
Total weight (Ib/day)
Weighted average concentration (mg/1)
Cu
1,410
1,990
980
4,380
0.25
Cr
780
690
570
2,040
0.12
Ni
930
650
430
2,010
0.11
Zn
2,520
6,920
1,500
10,940
0.62
Cd
95
110
60
265
0.015
* In reality, shockload discharges are much greater.
limited and 30% of these stream lengths
are polluted to a certain degree with
urban runoff. Hence, generally speaking,
secondary treatment of DWF is not suffi-
cient to produce required receiving water
quality; and control of runoff pollution
becomes an alternative for maintaining
stream standards. Accordingly, both
water quality planning and water pollution
abatement programs need to be based on an
analysis of the total urban pollution
loads.
Until the urban stormwater situation
is analyzed and efficient corrective
measures taken, there may be no point to
seeking higher levels of treatment
efficiency in existing plants. For
example:
—In Roanoke, VA domestic waste load
removal was upgraded from 86% to 93%,
yet there was no dramatic reduction in
the BOD load (3.2 million pounds before
upgrading, compared to 3.1 million pounds
after) (41) .
—If Durham, NC provided 100% removal of
organics and suspended solids from the
raw municipal waste on an annual basis,
the total reduction of pollutants dis-
charged to the receiving water would only
be 59% of the ultimate BOD, and 5% of
the suspended solids (112) .
These examples are for separate
systems. Communities with combined
systems offer a potentially greater
pollutional impact since additional
loads come from domestic wastewaters,
dry-weather sediment wash-out, and more
impervious and populated lands.
Receiving Water Quality Impacts
For the aforementioned Durham study
it was found that during storm flows.
dissolved oxygen content of the receiving
watercourse was independent of the degree
of treatment of municipal wastes beyond
secondary treatment. Oxygen sag estimates
were unchanged even if the secondary
plant was assumed upgraded to zero discharge,
and stormwater discharges governed the
oxygen sag 20 percent of the time.
There is an R&D study (P-68) in the
Milwaukee area to determine water quality
impacts from wet-weather discharges. This
study is being conducted in conjunction
with a Step 1 construction grant (Section
201 of PL 92-500) for the evaluation of
combined sewer overflow pollution and
control; and will provide the necessary
"receiving water impact" basis for these
evaluations.
Early results from direct receiving
water sampling in the Milwaukee River
provide strong evidence of CSO impacts on
intensifying D.O. sag and increasing fecal
coliform concentration. Figure 4 repre-
sents D.O. analyses for the Wells Street
sampling station that lies at the down-
stream portion of the combined sewer area.
Samples were collected at three hour
intervals during 72 hours of dry weather
during June 1975, averaged for the stream
cross-section, and followed approximately
nine days of antecedent dry weather. D.O.
values hovered around 6 to 8 mg/1.
Figure 5 is for the same Wells Street
location representing data from six days
of monitoring following a 0.26 inch rain-
fall on October 14-15, 1975. Continuous
monitoring at the site showed D.O. levels
between 5.0 and 7.8 mg/1 for the three days
prior to rainfall. (The lag between the
end of the storm and beginning of data
acquisition was due to equipment
391
-------
malfunction). The graph indicates a highly
significant D.O. sag to zero mg/1 and six
days after the storm required for recovery.
Adverse combined sewer overflow
effects on fecal coliform concentrations
in the Milwaukee River in the proximity
of Lake Michigan were also deciphered.
Figures 6 and 7 depict fecal coliform in
the Milwaukee River during the same dry-
and wet-weather monitoring periods as in
Figures 4 and 5, respectively. Addition-
ally/Figures 6 and 7 contain the Brown
Deer Road monitoring site which is well
above the intensely urbanized combined
sewer overflow area. There is nearly a
two log increase in enteric microorganisms
downstream in the CSO area after wet-
weather discharges indicating a potential
health hazard for the nearby Lake beach
fronts. Brown Deer Road showed no signi-
ficant difference in fecal coliform
concentration.
Due to Health Department findings,
shell fishing must cease in Narragansett
Bay in the vicinity of the Providence,
RI overflows for periods of seven and ten
days following rainfalls of one-half and
one inch, respectively.
Other studies (P-15, 157, R-3) based
on mass balance effects of urban runoff
in receiving waters have reinforced
these findings. A substantial additional
effort is planned to document the
receiving water impact of urban wet-
weather discharges.
Erosion/Sediment Impacts
Erosion-sedimentation causes the
stripping of land, filling of surface
waters, and water pollution. Urbanization
causes accelerated erosion, raising
sediment yields two to three orders of
magnitude from 1Q2 - 103 tons/sq mi/yr
to 104 - 105 tons/sq mi/yr (164). At the
present national rate of urbanization,
i.e., 4,000 ac/day, erosion/sedimentation
must be recognized as a major environ-
mental problem.
Nationwide Cost Assessment
Sewer Separation — The concept of
constructing new sanitary sewers to
replace existing combined sewers has
largely been abandoned for pollution
control due to enormous costs, limited
abatement effectiveness, inconvenience
to the public, and extended time for
implementation. The use of alternate
measures for combined sewer overflow
control could reduce costs to about one-
third the cost for separation (2, 102).
It is emphasized that sewer separation
would not cope with the runoff pollution
load.
High Costs Implied — However, even
in alternate approaches high costs have
been implied. The 1974 Needs Survey
(R-4) , the 1967 EPA survey by the American
Public Works Association (2), and the
1975 National Commission on Water Quality
(NCWQ) Report (R-5), identified national
costs for abating combined sewer overflow
pollution at $26 billion, or approximately
one-fourth of the total for municipal
sewage control. The cost of abating
separate stormwater pollution was estimated
at $235 billion by the Needs Survey and
$173 billion (for 75% BOD reduction) by
another NCWQ report (R-6).
There must be a more accurate
assessment of the problem both nationwide
and regional to provide the necessary
foundation for policy and law making,
and firmer pollution abatement targets —
realistically, can a job be done for the
money allotted?
New R&D Estimates Imply Lower Costs —
The recently completed Nationwide Assess-
ment Report (157) has attempted to more
accurately assess these national cost
estimates by reflecting a more logical
consideration of such items as: climate,
land usage, and degree of urbanization;
pollution abatement of storm flow only
and not separate, conventional flood
control; appropriate design flows; and
the benefits of optimized coordinated
systems of smaller storage-treatment
units not taken into consideration in
earlier estimates. The resultant
national cost for combined sewer overflow
and separate stormwater pollution control
was $23 billion at 75% annual BOD
removal (Curve A, Figure 8)(157). It is
estimated that the incremental costs for
combined sewer overflow pollution
abatement alone would be $9 billion
(Curve D, Figure 8).
392
-------
12.0,
Surface
/- -\
10 Foot Surface
0630 oooo oooo oooo
9 June 75 10 June 75 11 June 75
Time
9-
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7
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End of Storm
Start of Sampli ng
10 Foot Depth
II I I i 1 i ji~ i" i i i i i iTFTfTll I1IM l I i I i T nTVTTT r i ji i i I i I I 1 ]
15 Oct 16 Oct '7 Oct 18 Oct 19 Oct 20 Oct
Time
Figure 4. Dry Weather
Figure 5. Wet Weather
Dissolved Oxygen Concentration, Wells Street
Milwaukee River, Milwaukee, WI
-------
10'
<£>
10'
,o6
I
o 105
CD
•=«= L
10
o
o 10'
CJ>
10
Day
1
We 11 s
Brown Deer
i ,
Day
2
Day
3
Figure 6. Dry Weather
0
io
o
C_J
S
QJ
10
10
We 11s
Brown Deer
Figure 7. Wet Weather
Fecal Coliform Concentrations, Wells Street (CSO Area)
& Brown Deer Road (Separate Drainage Area)
Milwaukee River, Milwaukee, WI
-------
5400
SINGLE PURPOSE STORAGE - TREATMENT
ONLY
MULTIPLE PURPOSE PORTION OP STORAGE
TREATMENT COSTS ASSiGNEO TO OTHER
PURPOSES
SINGLE PURPOSE STORAGE-TR ETATMENT
AND BEST MANAGEMENT PRACTICES
SINGLE PURPOSE . STORAGE - THEATMtNT
ONLY RESULTS FOR COMBINED
SEWERED AREAS
U.S. URBAN POPULATION 149 XIC
U,S, DEVELOPED URBAN AhEA 15.6 X 10 ac
100
% BOD REMOVAL , R|
Figure 8. Single Purpose and Multiple Purpose Stormwater Pollution
Control Costs for US
395
-------
Additional national cost reductions
were shown by the multi-purpose coordin-
ated use of wet and dry weather flow treat-
ment facilities, and storm flow storage
facilities used as dual sedimentation-
treatment processes (see Curve B, Figure
8). Within certain control levels best
management practices, e.g., street clean-
ing and sewer flushing, could further
reduce control costs (Curve C, Figure 8).
When compared to prior studies the major
reduction in the national figure for
stormwater control is attributable to
discounting storm sewer line construction
(at $84 billion) and flood control (at
$73 billion).
Solution Methodology
The second area under Problem
Definition, "Solution Methodology"
naturally followed initial "Character-
ization" for providing a uniform and
necessary background for the user
community.
More Accurate Problem Assessment
Considering the limitations in the
presently available data base, the first
and most fundamental approach should be
a more accurate assessment of the problem.
Ideally, this should involve acquiring
data on a city-wide basis for both DWF
and wet-weather flow (WWF) including
upstream-downstream pollutants mass
balances and the effects of the waste
loads on the receiving waters.
Cost-Effective Approach
Integrated with a more accurate
assessment is the consideration of cost-
effective approaches to WWF pollution
control.
Present abatement alternatives
exhibit an extraordinary range of cost-
effectiveness. For example, cost-
effectiveness in terms of dollars/lb
of pollutant removed for an alternative
such as storage plus primary treatment,
varies over a range of 75:1, depending
on such factors as location and land
costs, type and condition of sewerage
systems, pollution loads, and type of
storage configuration. This very high
cost-effectiveness variability
demonstrates the irrationality of any
attempt to prescribe uniform national
standards for the technology of total
urban load abatement as opposed to
requiring site-specific studies.
There is an excellent opportunity
to bring down the high costs implied for
storm flow control. The most cost-
effective solution methodology must
thoroughly consider:
(1) Wet-weather pollution impacts in
lieu of blindly upgrading existing
municipal plants.
(2) Structural versus land management
and non-structural techniques. Studies
have indicated that it may be cheaper
to remove pollutants from the source by
such measures as street, catch basin, and
sewer cleaning than by eliminating them
by downstream treatment. Certain land
use, zoning, and construction site erosion
control practices are other ways of
alleviating the solids burden to the
receiving stream or treatment plant;
(3) Integrating dry and wet-weather
flow systems to make maximum use of the
existing sewerage system during wet
conditions and maximum use of wet-weather
control/treatment facilities during dry
weather; and
(4) The segment or bend on the per-
cent pollutant control versus cost curve
(see Figure 8 for example) where cost
differences increase at much higher rates
than pollutant control increases. This
phenomenon is caused by the need to size
storage-treatment facilities at dispro-
portionately greater capacities for the
less frequent storm events required for
higher pollutant controls.
Until two important philosophies are
allowed to prevail, the high cost impli-
cations for wet-weather pollution abate-
ment will continue. First, flood and
erosion control technology must be
integrated with pollution control tech-
nology so that the retention and drainage
facilities required for flood and erosion
control can be simultaneously designed
for integrated dual-benefits of pollution
control. Second, if land management
and non-structural techniques are maxi-
mized and integrated, there will be less
to pay for the extraction of pollutants
from storm flows in the potentially more
costly downstream plants.
396
-------
Example Solution Methodology
It is worthwhile to discuss a
hypothetical example of a cost-effective
solution methodology. Figure 9 represents
one such approach. This case is for D.O.
Actual studies should include other para-
meters and should represent at least one
year of continuous data (at a minimum rain-
fall data) . By this analysis a truer cost-
effectiveness comparison can be made based
on total time of receiving water impacts
and associated abatement costs. For
example, if a 5 mg/1 D.O. is desired in
the receiving water 75% of the time as a
standard, an advanced form of wet-weather
treatment or primary wet-weather treatment
integrated with land management is
required. The latter is the most cost-
effective at $3 million. This or similar
.methodologies (157, Chapter VII) can help
set cost-effective standards as well as
select alternatives.
There is a critical lacking of mean-
ingful water quality standards —
especially for storm flow transient
effects. This limitation forces the use
of (1) existing criteria not well backed
up by ecological receiving water effects,
or (2) arbitrary percent control of
combined sewer overflow or storm discharges.
A critical need exists for the technology
development sectors to join together with
the receiving water ecology sectors to
define and establish wet-weather receiving
water effects. It is felt that the
present state-of-the-art is advanced
far enough to generate approximate land
runoff pollutant loadings from different
control options and subsequent receiving
water pollutant concentration. By filling
the important gap of an adequate set of
receiving water quality standards, the
necessary foundation tools will be
available for a true cost-effective
solution methodology.
Administrative Problems
There are basic problems in
administration that must be overcome. In
the United States autonomous Federal and
local agencies and professions involved
in flood and erosion control, pollution
control, and land management and environ-
mental planning must be integrated at
both the planning and operation levels.
Multi-agency grant coverage must be
adequate to stimulate such an approach.
For example, EPA would have to join with
the Army Corp of Engineers, Soil
Conservation Service, Department of
Transportation, and perhaps other
Federal agencies as well as departments
of pollution control, sanitation, planning
and flood control at the local level.
EPA1s present policy of funding construction
will also need expansion to cover cost-
effective land management and non-struc-
tural techniques promulgated by its
planning grant approach.
Solution Methodology: Products
Highlighted solution methodology
products are the often referenced eight
city studies (41, 51, 53, 54, 49, 60, 65,
83) which involved an economic comparison
of pollution control alternatives for
both dry and wet weather flow.
The state-of-the-art (SOTA) text on
urban stormwater management and technology
(102) is considered an excellent program
milestone and guide for planners and
engineers. It organizes and presents
more than 100 completed Program projects
as of December 1973. The text is presently
being updated and will include comprehen-
sive guidelines for total city-wide, wet-
weather pollution control planning and
countermeasure selection (P-5). Other
in-house Program documents (111, R-6a,
R-6b, R-6c, R-6d, R-6e, R-6f, R-6g, R-6h,
R-6i) must also be included in this
category.
A film is available covering the
entire Program, and in particular full-
scale control technologies (R-7).
Program seminar proceedings (6, 40, 96)
with themes of "design, operation, and
costs" have been published. Urban
runoff seminar proceedings for 208 plan-
ning agencies (140a) are also available.
Separate engineering manuals are
available for urban storm flowrate and
volume determination (140, 123), storm
sewer design (71), and conducting urban
stormwater pollution and control studies
(145). SOTAs on storm flow measuring
(130) and sampling (87, 133) have also
been published. All these documents are
valuable references for the planning and
implementing of urban stormwater studies
for PL 92-500, 201, Step 1, and 208 grants.
397
-------
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D.O. (mg/l)
CONTROL
ALTERNATIVES
EXISTING
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WET-II (ADV)
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Figure 9. Example Solution Methodology
398
-------
In the area of "unit cost information"
a manual (156) is being published which
contains summary unit cost graphs on
construction and operation of the basic
urban stormwater storage and treatment
devices. An example on storage facility
construction costs is presented in Figure
10. Additional cost information and
equations can be obtained from the above-
mentioned text on urban stormwater manage-
ment and technology (102), the SWMM user's
manual (116), the nationwide stormwater
assessment document (157) , and the
manual for preliminary (level I) storm-
water control screening (153).
Other manuals are available for
deicing pollution (100, 104) and erosion
control (68, 70, 90, 92, 168, 169). The
SOTA document on size and settling velocity
characteristics of particles in storm and
sanitary water (115) is important because
it offers information for physical treat-
ability of suspended solids and anticipated
settlement in receiving waters. More
information of this nature, along with
the availability of pollutants with the
suspended solids, is needed. These,
along with the aforementioned solution
methodology documents, are or should be
serving for 201 and 208 studies.
Looking to the near future a city-
wide demonstration (P-15) of a multi-
faceted approach methodology is nearing
completion in Rochester, NY. The product
from this study will serve as an example
for other cities.
There is also an endeavor to study
direct receiving water impacts along with
verification of a water quality model.
This task will serve as an important
demonstration by lending credence to the
implications of storm flow impacts.
The previously discussed Milwaukee project
(P-68) covers this objective. Other
demonstration sites are being sought by
the Program. Receiving water impacts have
been included in an ongoing project in
Lancaster, PA (P-4) and additional non-
EPA funds to conduct a receiving water
impact analysis for the ongoing Rochester
project (P-15) have been secured.
USER ASSISTANCE TOOLS
The User Assistance Tools are divided
into "Instrumentation" and "Simulation
Models."
Instrumentation
The qualitative and quantitative
measurement of storm overflows is essen-
tial for planning, process design,
control, evaluation, and enforcement.
"Urban intelligence systems" require real-
time data from rapid remote sensors in
order to achieve remote control of a
sewerage network. Sampling devices do not
provide representative aliquots, and in-
line measurement of suspended solids and
organics is needed. Conventional rate-
of-flow meters have been developed mainly
for relatively steady-state irrigational
streams and sanitary flows and not for the
highly varying surges encountered in storm
and combined sewers. A schematic of
instrumentation development by the Program
is shown on Figure 11.
The electromagnetic (P-45), ultra-
sound (150), and passive sound (139)
flowmeters have been developed to overcome
these adverse storm flow conditions (which
require dual pressure-gravity measurement
of unsteady flows by non-intrusive
instrumentation). Further demonstration
of the electromagnetic and passive sound
flowmeters will take place shortly.
Passive sound instruments offer the
additional benefit of extremely low power
requirements rendering them amenable to
installation at remote overflow locations
(where power may not exist) and integration
into city-wide, in-sewer, sensing, and
control systems. A prototype sampler for
capturing representative solids in storm
flow, and overcoming storm flow adversities,
has been developed and compared with
conventional samplers. Favorable results
have been obtained and a design manual
(135) is available. Demonstration of two
previously developed instantaneous, in
situ monitoring devices for suspended
solids (113) (based on the optical
principle of suspended solids depolarizing
polarized light) and TOC (126) were
successfully conducted.
Separate SOTA reports for flow
measurement (130) and sampling (87, 133)
have been mentioned under problem
definition. A SOTA on organic analyzers
(110) is also available. Because storm
flow conditions are extremely adverse, the
manuals and instruments developed for the
Program in this area are useful for the
monitoring of all types of waste flows.
399
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Figure 10. Construction Cost Example: Storage Facilities
400
-------
PRE-FY76
FY76
FUTURE
RAIN
QUAN
(FLOW MEAS)
METER DEV
• DUAL GRAVITY-
PRESS
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Figure 11. Instrumentation for Total System Management
-------
Remote raingaging by radar is being
considered for an automated combined
sewer flow routing project in San
Francisco (P-25).
Instrumentation: Products
An instrumentation product summary
is listed on Table 3.
TABLE 3 - INSTRUMENTATION: PRODUCTS
Flow Measuring Devices Development
- Electromagnetic (open-channel and press flow) (P-45)
- Ultra-sound (150)
- Passive sound (139)
Sampler Development (135)
In situ suspended solids monitor development (113)
In situ TOC monitoring system development (126)
SOTA/Assessment reports
- Sampling (133)
- Flow measuring (130)
- Organics monitoring (110)
Simultation Models
Math models are needed to predict
complex dynamic responses to variable
and stochastic climatological phenomena.
Models have been subcategorized into
three groups: (1) simplified for prelim-
inary planning, (2) detailed for planning
and design, and (3) operational for
supervisory control (Figure 12).
The Storm Water Management Model
(SWMM) provides a detailed simulation of
the quantity and quality of stormwater
during a specified precipitation event.
Its benefits for detailed planning and
design have been demonstrated and the
model is widely used. However, for many
users it is too detailed; e.g., the 208
planning effort needs simplified proce-
dures to permit preliminary screening of
alternatives. Consequently, current
Program thinking on urban water management
analysis in general, and SWMM in particu-
lar, involves four levels of evaluation
techniques ranging from simple to complex
procedures than can be worked together.
The major portions of all four levels have
been developed (Table 4).
Planning/Design Models
Level I — The Level I procedure as
developed by the University of Florida
(153) was directly derived from the
previously mentioned nationwide cost assess-
ment project (157). This assessment docu-
ment already contains data on land use;
drainage system types; runoff volumes and
pollutant quantities; costs and cost-
effective control strategies for the 248
Standard Metropolitan Statistical Areas
in the Country. The information, also
itemized for States and EPA regions, can
be used in the early stages of problem
assessment, determining national cost
requirements and preliminary planning.
In Level I, a "desktop" statistical
analysis procedure permits the user to
estimate the quantity and quality of urban
runoff in the combined, storm and unsewered
portions of each urban area in his juris-
diction.
For example, under the University of
Florida approach, equations such as those
shown in Table 5 have been statistically
developed to estimate BOD , SS, VS, P04 and
402
-------
PRE-FY76
FY76
FUTURE
SIMPLIFIED
(PRE-PLAN)
DETAILED
(PLAN/DESIGN)
SIMPLIFIED
SWMM
• HRLY STEPS
• CONTINUOUS
M&E SIMPLIFIED
» SCREENING
• 400 VS 15000 STATEMENTS
1
1
J
| DEM. CITY-WIDE
j (ROCHESTER)
INCORP
HANDLING
INCORP
• IMPROVE
QUAL
DEPOSITION
• REUSE
• REC H2O
ECON
• H 9O USE
ECON
UWMM
OPERATIONAL
MANUAL SUPERVISORY
CONTROL DEMOS
(DETROIT, ST. PAUL, SEATTLE)
DEV AUTOMATIC
CONTROL
(SAN FRANSCICO)
DEM. AUTOMATIC
CONTROL
DISSEMINATION
SWMM
USER'S
MANUAL
T.T.
• USER ASSIST
PROG
• SHORT COURSES
('74, '75)
SWMM
»
MAN II
SWMM
MAN III
SWMM
MAN IV
UWMM
MAN
Figure 12. Simulation Models for Total System Management
-------
TABLE 4 - LEVELS OF URBAN WATER MANAGEMENT ANALYSIS
Preliminary: Print out information from Nationwide Assessment (157)
Level I: Desktop - no computer, statistical analysis
- UF Methodology (153)
- Hydroscience methodology (R-8)
Level II:
Simplified continuous simulation model
- Simplified SWMM (by M&E) (148)
Level III: Refined continuous simulation model
- Continuous SWMM (P-53)
- Storm (R-9, R-10)
Level IV:
Sophisticated single event simulation model
- Detailed SWMM (116, 125)
N loads as a function of land use, type of
sewer system, precipitation, population
density, and street sweeping frequency.
The a and (3 terms represent normalized
loading factors in Ib/ac-in., tabularized
as functions of land use, i and pollutant
type, j, for separate and combined areas,
respectively. These factors were derived
from a statistical review of available
stormwater pollutant loading and
effluent concentration data (157).
Similarly, Table 6 gives equations
for analyzing runoff for both stormwater
flow prediction and DWF prediction. Here
again the equations were based on a
statistical analysis of available data.
A generalized method for evaluating
the optimal mix of storage and treatment
and its associated costs has also been
developed. Also, procedures for comparing
tertiary treatment with stormwater manage-
ment and possible savings from integrated
management of domestic wastewater, storm-
water quality and stormwater quantity from
combined and separate drainage areas, are
available.
The Hydroscience approach offers
another procedure for assessing urban
pollutant sources, loadings, and
control. Both approaches, available in
the form of user's manuals, are being
published (153, R-8).
Level II — Level II involves a
simplified continuous model for planning
and preliminary sizing of facilities. The
model can run on daily time steps to screen
the entire history of rainfall records or
hourly time steps to screen the worst two
years. It is inexpensive to set up and
use, flexible enough to be applicable to
a variety of system configurations, and
accurate even though only very moderate
expenditures are made for data collection
and preparation. It is especially valuable
in sizing storage facilities based on storm
return periods and available in-line
capacity. A user's manual is available
(148).
Level III — Level III involves a more
refined continuous model approach (e.g.,
STORM, continuous SWMM) which in addition
to Level II provides for flow time routing
and continuous receiving water impact
analyses. The number of program statements
involved here is in the order of a few
thousand as compared to a few hundred for
the Level II effort. A user's manual
and program for STORM is available (R-9,
R-10). The continuous SWMM user's
manual is in preparation.
Level IV — The aforementioned three
levels essentially represent various
degrees of planning efforts and the
models involved are typified by relatively
large time steps (hours) and long simu-
lation times (months and years). Data
requirements are kept to a minimum and
their mathematical complexity is low.
404
-------
Table 5. Pollutant Analysis
The following equations may be used to predict annual average
loading rates as a function of land use, precipitation and population
density.
Separate Areas: M •= a(i,j) • P
Ib
Combined Areas:
where
P ' f2(PDd)
acre-yr
Ib
acre-yr
M =» pounds of pollutant J generated per acre of
land use i per year,
P = annual precipitation, inches per year,
PD = developed population density, persons per acre,
a,B factors given in table below,
Y street sweeping effectiveness factor, and
PD ) population density function.
Land Uses: i 1 Residential
i 2 Commercial
i 3 Industrial
i = 4 Other Developed, e.g., parks, cemeteries, schools
(assume PD.
0)
Pollutants: j
j
j
j
j
Population.
1 BOD , Total
2 Suspended Solids (SS)
3 Volatile Solids, Total (VS)
4 Total PO (as PO )
5 Total N
i 2,3
i - 4
2.
j
d
0.142 + 0.218
1.0
= 0.142
PD
0.54
Factors a and 8 for Equations: Separate factors, d, and combined factors,
ft, have units Ib/acre-in. To convert to kg/ha-cm, multiply
by 0.442.
Pollutant, j
Land Use, i 1. BOD 2. SS 3. VS 4. P04 5. N
1. Residential 0.799
Separate 2. Commercial 3.20
Areas, 20 days
s
405
-------
TABLE 6 - RUNOFF ANALYSIS
Stormwater Flow Prediction
AR = (0.15 + 0.75 1/100 P - 5.234 (DS)
AR = Annual Runoff, in/yr
0.5957
where
where
I = 9.6 PD
(0.573-0.0391 log PD )
where
I = Imperviousness, Percent and
PD = Population Density in Developed Portion of the
Urbanized Area, Persons/Acre
P = Annual Precipitation, in/yr and
DS = 0.25-0.1875 (I/WO) 0£ I _< 100
DS = Depression Storage, in. (0.005 < DS < 0.30)
Dry Weather Flow Prediction
DWF =1.34 PD,
a
where DWF = Annual Dry-Weather Flow, in/yr, and
PD, = Developed Population Density, Persons/Acre
a
Design models on the other hand are
oriented toward the detailed simulation
of a single storm event. They provide a
complete description of flow and pollutant
routing from the point of rainfall through
the entire urban runoff system and into
the receiving waters. Such models may be
used for predictions of flows and
concentrations anywhere in the rainfall-
runoff system and can illustrate the
detailed and exact manner in which abate-
ment procedures or design options affect
them. At such, these models are a highly
useful tool for determining least-cost
abatement procedures for both quantity
and quality problems in urban areas.
They are typified by short time steps
(minutes) and short simulation times
(hours). Data requirements are usually
very extensive. The EPA SWMM is such a
model. SWMM user's manuals and other
pertinent references that were revised
at a critical junctures are available
(42, 43, 44, 45, 116, 120). Eventually
is is hoped than SWMM can be expanded
into an Urban Water Management Model which
integrates both dry- and wet-weather flow
analyses including sludge handling capa-
bilities. This is emphasized in the
Program report on future direction of the
modeling development (136).
Operational Models
Operational models are used to
produce actual control decisions during
a storm event. Rainfall is entered
from telemetered stations and the model is
used to predict system responses a short
time into the future. Various control
options may then be employed, e.g., in-
system storage, diversions, regulator
settings. The Program has demonstrated
supervisory control models in Detroit
(118), Minneapolis-St. Paul (19), and
Seattle (29, 98); and has recently
started on a project in San Francisco
(P-25) taking advantage of a $100 million
construction grant, to develop a fully
automated operational model which includes
rainfall prediction.
Simulation Models: Products
Other simulation model products
include demonstration of a dissemination
and user assistance capability (122) and
development of a short course and course
manual (T25, P-51) for stormwater manage-
ment model application. Of particular
note is the SOTA assessment document on
18 available mathematical models for
storm and combined sewer management (141).
406
-------
TABLE 7 - SIMULATION MODELS: PRODUCTS
Development of a computer model (SWMM) for storm water management (42, 43, 44, 45)
Updated and refined user's manual modifying and improving SWMM (116).
Demonstration of a stormwater management model dissemination and user assistance
capability (122) .
User's manual for "desktop calculation" procedure for preliminary stormwater
management planning (153) .
User's manual for simplified model application for preliminary stormwater
management planning (148).
Course manual and seminar for stormwater management model application (125).
Assessment of mathematical models for storm and combined sewer management (141).
Refine and augment the capabilities of SWMM and develop decision-making
capabilities (120).
Evaluation of available runoff prediction methods for storm flowrate and volume
determination (140).
The document presents a summary of the
objectives, advantages and limitations of
each model along with a side-by-side
comparison to aid in assessing the
applicability of a model for a particular
purpose. Table 7 summarizes simulation
model products.
MANAGEMENT ALTERNATIVES
Wet weather flow control can be
assumed to involve aspects as follows.
First there is the choice as to where to
attack the problem: at the source (e.g.,
the street, gutters, and catchment areas)
by land management, in the collection
system, or off-line by storage. Pollutants
can be removed by treatment and by employ-
ing complex or integrated systems which
combine variations of control and treatment
including the dual-use of dry-weather
facilities. Second, there is the choice of
how much control or degree of treatment
to introduce. Thirdly, there is the impact
assessment, public exposure, and priority
ranking with other needs. The proper
management alternatives can only be made
after a cost-effective analysis involving
goals; values; and hydrologic-physical
system evaluations, generally assisted by
mathematical model simulations, pilot-
scale trials, and new technology transfer.
Land Management
Land Management includes all measures
for reducing urban and construction site
stormwater runoff and pollutants before
they enter the downstream drainage system
(Figure 13). On-site measures include
structural, semi-structural and non-
structural techniques that affect both
the quantity and quality of runoff.
Careful consideration must be given
to land use planning since urbanization
accelerates hydrograph and pollutograph
peaks and total loads by creating imper-
vious surfaces for pollutants and water
to run off from. This causes excessive
water pollution, erosion, sedimentation
and flooding. Discreet selection of land
management techniques can reduce drainage
and other downstream control costs
associated with these problems.
Until two important philosophies
prevail, the high cost implications
for wet-weather pollution abatement will
continue. Established flood and erosion
control technology must be integrated with
pollution control technology so that the
retention and drainage facilities and
other non-structural management techniques
required for flood and erosion control can
be simultaneously designed for pollution
control.
407
-------
LAND MANAGEMENT
o
oo
STRUCTURAL/ SUMI-STRUCTURALJ-
ON-SITE
(UPSTREAM)
STORAGE
CONSTRUCTION (HYDROLOGIC MODIFICATION) CONTROL j NON- STRUCTURAL
Erosion/Sedimentation (Construction )
Flood
Pollution
o RETENTION
Basins/Ponds
Recharging Ponds
o DETENTION
Basins /Ponds
Dual Use
Rooftop
Parking Lot/Plaza
Recreational Facilities
Aesthetics
POROUS PAVEMENT
o SWALES
OVERLAND o DIVERSION STRUCTURES
FLOW Ditches
MODIFICATION Chutes
Flumes
SOLIDS
SEPARATION
o SEDIMENT BASINS
o FINE SEDIMENT
REMOVAL SYSTEMS
Tube Settler
Upflow Filter
Rotating Disc Screen
o SWIRL DEVICE
SURFACE
SANITATION
o ANTI LITTER
o STREET CLEANING
o STREET FLUSHING
o AIR POLLUTION CONTROL
CHEMICAL
USE
CONTROL
o LAWN CHEMICALS
o INDUSTRIAL SPILLAGE
0 GASOLINE STATIONS
o LEAD IN GASOLINE
o HIGHWAY DEICING
URBAN
DEVELOPMENT
RESOURCE
PLANNING
USE OF NATU-
RAL DRAINAGE
EROSION
SEDIMENTATION
CONTROL
o COMPUTER SIMULATION
Land Use
Population Density
Control Options
o MARSH TREATMENT
o CROPPING
Seeding
Sodding
o SOIL CONSERVATION
Mulching
Chemical Soil
Stabilization
Berming
Figure 13. Land Management
-------
Structural/Semi-Structural Control
Structural and semi-structural control
measures require physical modifications in
a construction or urbanizing area and
includes such techniques as: on-site
storage, porous pavement, overland flow
modifications and solids separation.
Qn-Site (Upstream) Storage — On-site
or upstream storage refers to detention
(short term) or retention (long term) of
runoff prior to its entry into a drainage
system. Simple ponding techniques are
utilized on open areas where stormwater
can be accumulated without damage or
interference to essential activities.
Oftentimes, on-site storage does or can
be designed to provide for the dual or
multi-benefits of aesthetics, recreation,
recharge, irrigation, or other uses. For
example, in Long Island, NY, groundwater
supplies are being replenished by retention-
recharge. The dual benefit of recharging
is stressed because urbanization depletes
groundwater supplies; however, potential
groundwater pollution must also be
considered.
Successful variations of detention
that take advantage of facilities
primarily used for other purposes are
ponding on parking lots, plazas,
recreation and park areas; and ponding
on roof tops. The fundamental approach
is the same as for other forms of detention
but low cost is implied. Dual purpose
basins used for recreation and athletics
when dry are also employed.
Surface ponding is the most common
form of detention being used by developers.
Apparent economic benefits of surface
ponding for flood protection are derived
from the savings over a conventional
sewer project. Several surface ponding
sites are listed in Table 8 where a cost
comparison is made between a drainage
system using surface ponds to decrease
peak flows and a conventional storm sewer
system. It is important to note that
pollution and erosion control benefits
of the basins are not included in this
comparison.
Porous Pavement — Another approach
to stormwater management is the use of an
open graded asphalt-concrete pavement
which under pilot testing has allowed
over 70 in./hr. of stormwater to flow
through (Figure 14) (64). Stability,
durability, and freeze-thaw tests have
been positive and it is comparable in
cost to conventional pavement. Long-term
tests are still required to evaluate
clogging resistance and the quality of
water that filters through. If the soil
porosity under the pavement allows free
drainage there will be no water residue;
however, the coarse sub-base and porous
nature of the pavement can serve for
ponding capacity if storm quantities exceed
soil infiltration. A 4-inch pavement and
6-inch base could store 2.4 in. of runoff
volume in its voids. The proven use of
porous pavement can be an important tool
in preserving natural drainage and
decreasing downstream drainage and
pollution control facility requirements.
As a result of Program studies a feasibility
report (64) is available. The Program is
currently evaluating a porous pavement
parking lot (P-16) and results of this
study will be available next year.
AGGREGATE GRADED fO
A WATER FLOW OF
EXCEEDED
THE
MINIMUM MAR-
SHALL STABILITY
CRITERION
FOR \
MEDIUM TRAFFIC \
USES
AEROBIC AC
*&&
|fig|
riviTY UGHS
UNDER PAVEMENT — IvS^
NOT IMPAIRED P5ȣ
DURABILITY TEST /
INDICATED THAT /
HEIGHTENED EX-
POSURE TO AIR OR
WATER DID NOT PRO-
DUCE ASPHALT
HARDENING
/' •'''•'•"'•',
5.5*BY WT. OF
85-100 PENETRATION
ASPHALT CEMENT
BINDER
JBfek ,/ ••''•'•
ffl|?
?"^*J: ' ' - .;:''.V
'>%£$ SUBJECTED TO 2S5
*-~\ • FREEZE-THAW CY-
N^ CLES WITH NO ;
CHANGES IN PHYS-
ICAL DIMENSIONS.
MARSHALL STABILITY'
VALUES OR FLOW
RATES..*
Figure 14 - Porous Asphaltic-
Concrete Features
Overland Flow Modification — Another
form of structural and semi-structural
control is overland flow modification
including swales and diversion structures
(e.g., ditches, chutes, flumes). These
modifications are usually of lower cost
than subterranean sewer construction and
importantly allow vegetative cover and soil
infiltration to reduce runoff and pollutant
loadings.
409
-------
TABLE 8 - COST COMPARISON BETWEEN
AND CONVENTIONAL SEWER
Site Description
Earth City,
Missouri
Consolidated
Freightways ,
St. Louis,
Missouri
Ft. Campbell,
Kentucky
Indian Lakes
Estates, Blooming-
ton, Illinois
A planned community in-
cluding permanent rec-
reational lakes with
additional capacity for
storm flow
A trucking terminal using
its parking lots to de-
tain storm flows
A military installation
using ponds to decrease
the required drainage
pipe sizes
A residential development
using ponds and an
existing small diameter
drain
SURFACE PONDING TECHNIQUES
INSTALLATION (R-8)
Cost Estimate, $
With Surface
Ponding
2,000,000
115,000
2,000,000
200,000
With Conventional
Sewers
5,000,000
150,000
3,370,000
600,000
Solids Separation — Sediment basins
trap and store sediment from erodible areas
in order to conserve land and prevent
excessive siltation downstream. If designed
properly, these basins can remain after
construction for on-site storage. A
project (P-46) is evaluating the efficiency
of sediment basins.
Because a significant portion of the
eroded solids may be colloidal or unsettle-
able and therefore cannot be treated in
conventional sedimentation basins, special
devices for fine-particle removal are
required. An ongoing project (P-73)
has developed a SOTA (163) on methods for
fine-particle removal and is now under-
taking the evaluation of three solids
separation devices (i.e., tube settler,
up-flow filter, and rotating disc screen).
The swirl concentrator has been
developed for erosion control (P-3, 99) to
remove settleable solids at much higher
rates than sedimentation. A prototype
device is presently being evaluated at a
construction site (P-74).
Non-S tructural
Non-structural control measures
involve surface sanitation, chemical use
control, urban development resource
planning, use of natural drainage, and
certain erosion/sedimentation control
practices (Figure 13).
Surface Sanitation — Maintaining
and cleaning the urban area can have a
significant impact on the quantity of
pollutants washed off by stormwater.
Cleanliness starts with reduction of
litter and debris at the neighborhood
level. Both street repair and street
sweeping can further minimize the pollutants
washed off. It has been estimated that
street sweeping costs per ton of solids
removed are about half the costs for
solids removed via the sewerage system.
The effectiveness of street sweeping
operations with respect to stormwater
pollution has been analyzed by EPA (73,
88, 128, 157, P-49). It was found that
a great portion of the overall pollution
potential is associated with the fine
solids fraction of the street surface
410
-------
TABLE 9 - ADVANCED* STREET CLEANER POLLUTANT RECOVERY PERCENTAGE
Parameter
Dry Weight Solids
Volatile Solids
BOD
COD
Total PO4-P
Heavy Metals
% Recovery
93
80
67
84
85
83-98
*Broom and Vacuum Combination
contaminants and that only 50 percent of
the dry weight solids are picked up by
conventional broom sweepers (73) as compared
to 93 percent removal by more advanced
techniques (128) (Table 9).
Cities clean their streets for aesthe-
tic reasons, removing the larger particles
and brushing aside the fines. Conventional
sweepers are utilized and satisfy the
aesthetics problem. More advanced street
cleaning procedures such as a combination
of sweeping and vacuuming would not only
satisfy the aesthetics problem but would
also attack the source of stormwater
related pollution problems by removing
the finer or more pollutant prone range
of particles.
Further verification of the benefits
of street cleaning will be carried out in
an ongoing grant (p-25). Also, a desktop
analysis comparing the cost-effectiveness
of street cleaning and sewer flushing
with downstream treatment methods is near-
ing completion under another study (P-73) .
Flushing of streets can be used to remove
street contaminants effectively; however,
it may necessitate more frequent catch
basins and sewer cleaning. Street
cleaning is estimated to cost $3 to $13/
curb mi or about $0.75/ac.
Air pollution abatement plans must
also consider water pollution reduction
benefits from decreased fall out.
Chemical Use Control — One of the
most overlooked measures for reducing
the pollution potential from neighborhood
areas is the reduction in the indiscrim-
inate use of chemicals such as fertilizers
and pesticides, and the mishandling of
other materials such as oil, gasoline,
and highway deicing chemicals. Aside
from air pollution control, de-leaded
gasoline also results in water pollution
control.
The progression of studies in deicing
chemical control, and resulting reports, is
depicted in Figure 15. The Program's
motivation from the start has been to
determine the extent of environmental
damages and costs associated with the use
of chemical deicers so that the economic
validity of alternative approaches could
be assessed.
Until the Program's assessment of the
problem in 1971 (67) there had been only
limited research on highway deicing effects.
Inquiries concerning this work indicated
such an increased public awareness of the
salt problems, that it seemed appropriate
to firm up recommendations for alternatives
to snow and ice control. A search was
conducted (76) to define alternatives.
The need for an accurate economic impact
analysis of using deicing salt, and a
requirement to identify a substance which
can be applied to pavement to reduce ice
adhesion was indicated. These two needs
became projects which have recently been
completed (138, 152). Hydrophobic
substances have been identified and are
being investigated, and even though
material and application costs appear
greater than for salt (0.20-0.25/yd versus
$0.03/yd2), when considering total damage
to the environment ($3 billion annually.
including paved area, highway structures
and vehicles) the costs are acceptable.
411
-------
ASSESSMENT OF PROBLEM (67)
Rept: Environmental Impact of
Highway Deicing 6/71
EVALUATION OF APPROACHES (76)
Rept: A Search: New Technology for
Pavement Snow & Ice Control 12/72
SOTA REVIEW (86,R-11)
Rept: Water Pollution and Associated
Effects from Street Salting 5/73
— ATTEMPTS AT A SOLUTION
MANUALS OF PRACTICE (100,104)
Rept: Manual for Deicing Chemicals
Storage and Handling 7/74
Rept: Manual for Deicing Chemicals
Application Practices 12/74
ECONOMIC ANALYSIS OF COSTS OF DEICING (138)
Rept: An Economic Analysis of the
Environmental Impact of Highway Deicing 5/76
ALTERNATIVE MATERIAL DEVELOPMENT (152)
Rept: Dev. Hydrophobic Substance to
Mitigate Pavement Ice Adhesion 10/76
(OPTIMIZE HYDROPHOBIC SUBSTANCE (P-70)|
--^Ongoing Study: Washington [
jState_ University 9/77 J
Figure 15. Deicing Chemical Control (Land Management/Non-Structural)
412
-------
After the 1973 assessment of the
problem (86, R-ll) , the Program recognized
that it was not practical to ban salt
since the "bare pavement" philosophy
was very popular and considered by most
highway authorities as the safest way
for ice and snow removal. The major
problems were identified with careless
salt storage practices and over-application
on highways, consequently, a 1974 project
resulted in manuals of practice for
improvement in these areas. These manuals
(100, 104) were recognized as highly
significant by the user community. To date,
over 7000 copies have been distributed.
Urban Development Resource Planning —
The goal of urban development resource
planning is to develop a microscopic
management concept to prevent the
problems resulting from shortsighted
urbanization plans. As previously dis-
cussed, the planner must be aware of total-
ly integrating planned urban hydrology
with erosion-sedimentation and pollution
control. This new breed of planner has
to consider the new land development
planning variables of land usage,
population density and total wet and dry
runoff control as they integrate to effect
water pollution. Computer simulation will
most likely play an important role. A
simple land planning model has been
developed by G. K. Young (140a, Chapter
I, pp 98-121) to encompass the pertinent
variables and the most effective control
options based upon receiving water
pollutant absorption capacity. A new
project is planned to perfect this area.
Use of Natural Drainage — The
traditional urbanization process upsets
the existing water balance of a site by
replacing natural infiltration areas and
drainage with impervious areas. The net
impact is increased runoff, decreased
infiltration to the groundwater and
increased flowrates, all contributing
to increased channel erosion and the
transport of surface pollutants to the
stream. Promulgating the use of natural
drainage concepts will reduce drainage
costs; enhance aesthetics, groundwater
supplies, and flood protection; and
lower pollution.
A project in Houston (p-16) focuses
on how a "natural drainage system" can
be integrated into a reuse scheme for
recreation and aesthetics. Good land
use management will allow runoff to
flow through low vegetated swales and
into a network of wet-weather ponds,
strategically located in areas of porous
soils. This sytem will cause some of
the runoff to seep into the ground and
retard the flow of water downstream, thus
preventing floods caused by development
and enhancing pollution abatement.
The concept of considering urban runoff
as a benefit as opposed to a wastewater,
in a new community development, will be
employed and evaluated.
Another project in Wayzata, MN (P-28)
is using marshland for stormwater treat-
ment. After sufficient testing it has
been determined that controlled stormwater
retention in the marsh resulted in better
vegetative conditions which in turn
enhanced stormwater nutrient removal.
It was found that if the marshlands were
filled in by urbanization it would have a
detrimental effect on the nearby lake.
Erosion/Sedimentation Control (Non-
Structural) — Other nonstructural soil
conservation practices such as cropping
(seeding and sodding) and the use of
mulch blankets, nettings, chemical soil
stabilizers and berming may be relatively
inexpensive. Two ongoing projects (P-72,
P-74) are evaluating many of these
low structural intensive management
practices for proposed erosion control
manuals.
Integrated Benefits
While the flood control benefits of
all the above land management control
measures are easy to see, the stormwater
pollution and erosion control effects
are difficult to quantify. But briefly
stated, detaining or retaining flow
upstream offers the opportunity for flow
quiescence resulting in solids separation.
It also decreases downstream drainage
velocities and discharges to streams
resulting in less overflow pollution,
siltation and scour. Aside from causing
downstream erosion, this scouring can
also increase pollution loads in the
scouring stream.
413
-------
Erosion/Sediment Control: Products
By showing the genealogy of the
products through past milestone events
(Figure 16) the strategy which has guided
the Program in this category can be
demonstrated. The original "Guidelines
for Erosion and Sediment Control Planning
and Implementation" (70) are still
applicable to communities initiating an
urban sediment control program.
For erosion-sedimentation controls,
many agencies (e.g.. The Department of
Transportation and Soil Conservation
Service, and state and local departments)
and factors must be considered and
interrelated in product development and
technology implementation. For example,
the Soil Conservation Service has pub-
lished a document with the State of
Maryland entitled, "Standards and
Specifications for Soil Erosion and
Sediment Control in Developing Areas"
(R-12). Other states are using this
document as a model ordinance. Local laws
will have an important impact on any Best
Management Practices proposed by EPA.
Therefore, there must be close liaison
between all groups.
A recently developed training program
consists of an instructor's manual (168),
a workbook (169), and 2762 slides with
integrated audio cassettes. The program
is directed to the local land developer
and inspector, the excavation contractor,
and the job foreman. It is designed to
directly support the Maryland "Standards
and Specifications for Erosion and
Sediment Control in Developing Areas."
As the state and local agencies move
toward setting standards for control on
non-point sources, the need for this type
of training program becomes urgent.
Future Program plans include an
evaluation of various cities' erosion
control programs. This product will be
the foundation for National Standards and
Specifications for sediment and erosion
control in developing areas and with the
findings of the Urban Runoff Program will
lead to the National Best Management
Practice for this category.
COLLECTION SYSTEM CONTROLS
The next category, collection
system control (Figure 17) pertains to
those management alternatives concerned
With, wastewater interception and transport.
These alternatives include sewer separation;
improved maintenance and design of catch
Basins, sewers, regulators and tide gates;
and remote flow monitoring and control.
The emphasis, with the exception of
sewer separation, is on optimum utilization
of existing facilities and fully automated
control. Because added use of the exist-
ing system is employed, the concepts
generally involve cost-effective, low-
structurally intensive control alternatives.
To accomplish this an extensive and
dependable intelligence system is
necessary.
Catch Basins
A project is assessing the value of
catch basins (P-17, 174) as they are
presently designed and maintained. Opti-
mized basin configuration, design and
maintenance for removing solids before
sewerage system entry have also been
investigated. Evaluations showed that
a catch basin contains approximately
0.18 Ib-BOD or the equivalent of one
person's daily contribution. The
utilization of catch basins can either
contribute to the pollutional load or
aid in reducing downstream treatment
depending on their design and maintenance.
Sewers
Solids deposition in lines has always
been a plague to effective maintenance.
Recently, the significance of such loads
as a major contributor to first flush
pollution has been recognized (P-66; 140a,
Chapter II, pp 62-82).
Work is being conducted on new sewer
designs for low flow solids carrying
velocity to alleviate sewer sedimentation
and resultant first flush and premature
bypassing (P-50); and also on sewer
designs for added storage (P-13, 165).
As a natural follow-up to Program work
with a controlled test loop (13, 14), a
project has just been initiated to
demonstrate periodic sewer flushing during
dry weather for first flush relief (P-66).
Polymers to Increase Capacity —
Research (6, 11, P-6) has shown that
polymeric injection can increase flow
capacity as much as 2.4 times (at a
constant head). This method can be used
414
-------
1
COMMUNITY (R-12)
GUIDEBOOK 3/70
'
DEMONSTRATION
PROJECTS
(89,90,91)
!
EXECUTI
SUMMAR
i
f
URBAN SOIL (68)
EROSION 5/70
GUIDELINES (70)
PLANNING
IMPLEMENTATION 8/72
,
VE (92)
Y 2/74
-
~>
INTER AND (167)
INTRA AGENCY
PROJECTS
jf^^"
DEMONSTRATION (90)
FOR
SPECIALISTS 6/74
]
\
« >
SUMMARY (167)
STATE
PROGRAMS 3/75
^
AUDIOVISUAL (168,169)
TRAINING PROGRAM 8/76
1
STANDARDS & (R-13)
SPECIFICATIONS
USDA-SCS 6/75
[REGIONAL (p-72,73,74)' i
I TECHNIQUES 6/77 i "**!
I ___________ . I
TECHNICAL
EVALUATION 1/78
y
i NATIONAL
j STANDARDS &
SPECS. FOR BMP 6/78
URBAN RUNOFF PROJECTS
Figure 16. Erosion/Sedimentation Control: Products
415
-------
PRE-FY76
FY76
FUTURE
SEPARATION
< FEASIBILITY STUDY
RUNOFF INLETS/
CATCH BASINS
• EFFECTIVENESS
• CLEANING
• NEW DESIGN
REGULATORS/ TIDE GATES
• SOTA/MOP
• DEVICE DEV/DEM.
-FLUIDIC
-FABRE DAM
-POSITIVE GATES
-SWIRL/HELICAL
• MOP TIDE GATES
SEWERS
EXISTING
• FLUSHING
• POLYMER
• I/I CONTROL
-SOTA/MOP
-INST/DETECTION
-EVAL. METHODOLOGY/
UPDATE MOP
-SEALING 4 LINING
NEW (NON-STRUCTURAL)
• I/I PREVENTION
-INSPECTION
-CONSTRUCTION MATERIALS
-CONSTRUCTION TECHNIQUES
-IMPREGNATION
•NEW DESIGN
-CARRYING VEL.
- ADDED STORAGE
DEM. SEWER
FLUSHING
DEM. SULFUR
IMPREGNATION
FOR IMPROVED
STRENGTH
CATCH BASIN DEM.
DEM. NEW
SEWER DESIGN
TT DESIGN MANUAL
ON SWIRL/HELICAL
SWIRL/HELICAL
DEM. COMPARISON
TIDE
GATE DEVICE DEV.
FLOW ROUTING
•DEM. IN-LINE STOR.
•SELECTIVE RELEASE
•REMOTE SENSING/CONTROL
• DEV. TOTAL AUTO./SEW-
ERAGE SYS. CONTROL
CONTINUATION
OF AUTO. SYS.
CONTROL DEV.
DEM. CITY-WIDE SYSTEM
Figure 17. Collection System Control
-------
as a short or long-term correction of
troublesome pollution-causing conditions
such as localized flooding and excessive
overflows. Direct cost savings may be
realized by eliminating relief sewer
construction (6); however, additional
cost verification at the site is necessary.
Infiltration/Inflow — The Program
SOTA (27) and manual of practice (MOP)
(28) on infiltration/inflow (I/I) identi-
fied a significant problem which led to
fruitful countermeasure research and a
national emphasis on I/I control. Program
developments have included detection
methodology and instrumentation (27, 28,
10); preventive installation and construct-
ion techniques, new and improved materials
(.22, 27, 28, 52, 61, P-31, P-41) ; and
correction techniques (12) . A project
to update and develop practices for
determining and correcting infiltration
and its economic analysis (P-18, 166) is
nearing completion. An in-house paper
on the analysis and evaluation of I/I has
been published (R-14). Another project
is evaluating the strength increases and
erosion resistance, and resulting infil-
tration prevention from sulfur impregnation
of concrete pipe (P-30, 52). Since pipe
costs are significant, an increase in
strength could lead to a decrease in pipe
materials and construction costs.
Flow Routing
Another collection system control
method is in-sewer or in-line storage
and routing of storm flows to make
maximum use of existing interceptors
and sewer line capacity. The general
approach comprises remote monitoring of
rainfall, flow levels, and sometimes
quality, at selected locations in the
network, together with a centrally
computerized console for positive
regulation. This concept has proved to
be effective in Minneapolis-St. Paul (19) ,
Detroit (40, 118), and Seattle (29, 98).
Seattle results are discussed later
(Section 7, pp 56-58) to indicate
potential control and cost benefits.
An ongoing project mentioned earlier
with the City of San Francisco is develop-
ing an automatic operational model for
real-time control (P-25). Future demon-
stration of the system is anticipated.
Regulators and Tide Gates
Two early publications in the area
of flow regulator technology were the
SOTA (23) and MOP (24).
Conventional regulators malfunction
and cause excessive overflows. The new
improved devices such as fluidic and
positive control regulators have been
developed and demonstrated (P-7, 9, 23,
24, 98, 173). The swirl and helical
regulator devices are significant enough
to single out separately.
Swirl and Helical Device Development
— The dual functioning swirl device has
shown outstanding potential for providing
both quality and quantity control (R-15,
93).
A swirl flow regulator/solids-liquid
separator has been demonstrated in
Syracuse, NY (P-2; R-16; 140a, Chapter II,
pp 99-117). Figure 18 is an isometric
view. The device, of simple annular
shape construction, requires no moving
parts. It provides a dual function,
regulating flow by a central circular
weir while simultaneously treating
combined wastewater by a "swirl" action
which imparts liquid-solids separation.
The low-flow concentrate is diverted via
a bottom orifice to the sanitary sewerage
system for subsequent treatment at the
municipal works, and the relatively clear
supernatant overflows the weir into a
central downshaft and receives further
treatment or is discharged to the stream.
The device is capable of functioning
efficiently over a wide range (80:1) of
combined sewer overflow rates, and can
effectively separate suspended matter at
a small fraction of the detention time
required for conventional sedimentation
or flotation (seconds to minutes as opposed
to hours by conventional tanks). Tests
indicate at least 50 percent removal of
suspended solids and BOD. Tables 10 and
11 contain further treatability details
on the Syracuse prototype. The captial
cost of the 6.8 mgd Syracuse prototype
was $55,000 or $8,100/mgd and $l,000/ac
which makes the device highly cost-
effective.
The swirl concept (for dual dry/wet
weather flow treatment) has been piloted
417
-------
as a degritter (P-71) in Denver, CO and as
a primary clarifier in Toronto, Canada
(P-71). Test results are very encouraging
and the concept has been further developed
for erosion control.
A helical or spiral-type regulator/
separator has also been developed based on
principles similar to those of the swirl
device. Its solids separation action is
created by only a bend in the sewer line.
It requires more land than the swirl
device but may be preferred where
available hydraulic head is limited.
Swirl and Helical: Products — Impor-
tant products for this category are design
manuals for the swirl (69, 93, 101) and
helical (132) regulator/separators, swirl
degritter (99) and swirl erosion control
devices (151); and a Technology Transfer
Capsule Report (162) which ties the
various swirl applications together.
Maintenance
Improved sewerage system inspection
and maintenance is absolutely necessary
for a total system approach to municipal
water pollution control. We cannot afford
the upgrading and proper operation
of sewage treatment plants while a
significant amount of sewage leaks into
streams at the upstream points in the
sewer network! Premature overflows
and backwater intrusions during dry as
well as wet weather caused by malfunction-
ing regulators and tide gates, improper
diversion settings, and partially filled
interceptors can thus be alleviated.
Although the resulting abatement obtained
is from a non-structural approach, it must
be viewed as an ancillary benefit of
required system maintenance. Regulator
agencies should be anxious to strive for
policy to enforce collection system
maintenance.
LEGEND
o InUt Ramp
b Flow Deliverer
c 5
-------
1971
1972
1973
1974
1975
1976
FUTURE
DEM. UNDERWATER
STORAGE (BAGS)
EVALUATE IMPACTS OF
SOLIDS FROM STOR.
FAC. ON DWF PL.
IN-SEWER STORAGE
BY REMOTE CONTROL
OFF-LINE STORAGE
(TANKS/BASINS)
DEEP TUNNEL STOR.
& ROUTING
DESIGN MANUAL FOR
STORAGE FACILITIES
DEM. NEW
CONFIGURATIONS
FOR STORAGE FAC.
F/S DEM.-SILO,
UNDERWATER BAGS,
FLOW ROUTING
EVAL. SEEPAGE BASINS
(CSO/SWR) (RECHARGE)
DEM. STORAGE W/
CONTROLLED RELEASE
TO REC. WATER
EVAL. DUAL STORAGE
OF DWF/WWF W/
SECONDARY POLISHING
Figure 19. Storage
-------
TABLE 10 - SWIRL REGULATOR/CONCENTRATOR: SUSPENDED SOLIDS REMOVAL
Storm No.
02-1974
03-1973
07-1974
10-1974
14-1974
01-1975
02-1975
06-1975
12-1975
14-1975
15-1975
SWIRL CONCENTRATOR
Mass Loading
kg
% b
Inf. Eff. Rem.
374 179 52
69 34 51
93 61 34
256 134 48
99 57 42
103 24 77
463 167 64
112 62 45
250 168 33
83 48 42
117 21 82
Average SS
per storm, mg/1
% b
Inf. Eff. Rem.
535 345 36
182 141 23
110 90 18
230 164 29
159 123 23
374 167 55
342 202 41
342 259 24
291 232 20
121 81 33
115 55 52
CONVENTIONAL REGULATOR
Mass Loading
kg
%
Inf. Underflow Rem.a
374 101 27
69 33 48
93 20 22
256 49 19
99 26 26
103 66 64
463 170 34
112 31 27
250 48 19
83 14 17
117 72 61
For the conventional regulator removal calculation, it is assumed that the SS
concentration of the foul underflow equals the SS concentration of the inflow.
Data reflecting negative SS removals at tail end of storms not included.
TABLE 11 - SWIRL REGULATOR/CONCENTRATOR: BOD REMOVAL
Storm No.
7-1974
1-1975
2-1975
Mass Loading, kg
%
Influent Effluent Rem.
277 48 82
97 30 69
175 86 51
Average BOD
per storm, mg/1
Influent Effluent
314 65
165 112
99 70
^0
Rem.
79
32
29
The concept is to capture wet-weather
flow and bleed it back to the treatment
plant during low flow dry-weather
periods. The result of controlling
overflow by detention is shown on Figure
20. Notice how an entire hypothetical
overflow event at point A is prevented by
storage with controlled dewatering.
RAINFALL
T
HYDROGRAPH AT "A"
WITHOUT CONTROL
CONTROLLED
HYDROGRAPH AT
"A"
Figure 20 - Results of Controlling Storm
Flow by Storage
420
-------
Storage facilities possess many of the
favorable attributes desired in combined
sewer overflow control: (1) they are
basically simple in structural design
and operation; (2) they respond without
difficulty to intermittent and
random storm behavior; (3) they are
relatively unaffected by flow and quality
changes; and (4) they are capable of
providing flow equalization and, in the
case of sewers and tunnels, transmission.
(Frequently they can be operated in
concert with regional dry-weather flow
treatment plants for benefits during
both dry- and wet-weather conditions
(107)). Finally, storage facilities
are relatively fail-safe and adapt well
to stage construction.
Storage facilities may be constructed
in-line or off-line; they may be open or
closed; they may be constructed inland
and upstream, or on the shoreline; they
may have auxiliary functions, such as
flood protection, sewer relief, and
flow transmission. (And they may be
used for hazardous spill containment
during dry weather.)
Disadvantages of storage facilities
are their large size and dependency on
other treatment facilities for dewatering
and solids disposal.
Storage concepts investigated by the
program include the conventional concrete
holding tanks (18, 134) and earthen basins
(30, 72); and the minimum land require-
ment concepts of: tunnels (40), underground
(85) and underwater containers (15, 25,
26), underground "silos (96)," gravel
packed beds with overhead land use (154) ,
natural (85) and mined under and above
ground formations, and the use of aban-
doned facilities and existing sewer lines
(19, 29, 98, 118).
A 3.5 mg asphalt-lined storage
basin in Chippewa Falls, WI (72) was
constructed on reclaimed land and
eliminated 59 out of 62 overflows during
the evaluation periods.
Inherent in many of these storage
schemes is the pumping/bleeding back of
the stored flow to the DWF plant during
off-peak hours. The impacts of this
increased load on the DWF plant (both
from a hydraulic and increased solids
point of view) is an important
consideration and has been investigated
in an ongoing project (159, 161).
The feasibility of off-line storage
and deep tunnel storage along waterways
for selective discharge based on least
receiving water impacts is presently
being investigated in Rochester, NY (P-15).
It is envisioned that this concept along
with dual DWF/WWF storage, will be
demonstrated in post FY 76 plans as
part of a tie-in to construction grants.
Future Program plans include the
investigation of new storage configurations,
e.g., floating storage facilities, coffer-
dams, storage under piers, etc. Full-
scale demonstration of some of the more
promising configurations, such as silos
and underwater bags, is also desirable.
Treatment
Due to adverse and intense flow
conditions and unpredictable shock load-
ing effects, it has been difficult to
adapt existing treatment methods to storm-
generated overflows, especially the
microorganism dependent biological
processes. The newer physical/chemical
treatment techniques have shown more
promise in overcoming these adversities.
To reduce capital investments, projects
have been directed towards high-rate
operations approaching maximum loading
boundaries. Applications include pre-
treatment or roughing, main or sole
treatment, and particularly with micro-
strainers and filters, polishing devices.
The various treatment methods which
have been developed and demonstrated
by the Program for storm flow include
physical and physical-chemical, biological,
and disinfection (Figure 21). These
processes, or combinations of these
processes, can be adjuncts to the existing
sanitary plant or serve as remote
satellite facilities at the outfall.
Physical/Chemical Treatment
Physical processes with or without
chemicals, such as: fine screens (34,
37, 38, 78, 105); swirl primary separators
(162, P-29) and swirl degritters (99, 162,
158, P-29); high-rate filters (35, P-39);
sedimentation (36, 81); and dissolved air
flotation (20, 21, 131); have been
developed and demonstrated by the Program.
421
-------
PRE-FY76
FY76
FUTURE
PHYSICAL
W/ OR W/O
CHEM
DEV/PILOT
• FINE SCREENS
• SWIRL-GRIT/PRIM
• HI-RATE FILT
• DISS AIR FLOAT
• NH3:ION EX.BK PT
• P-C (AWT)
\
x \
\
\
DEM FULL-SCALE
• FINE SCREENS
• COAG SEDfCS/SW)
• SWIRL DEGRITTER
• HRF
• DAF
\
1 1
FINE SCREEN 1 DUAL USE 1
DEM.(CONT) ' SCREENING I
DEM FULL-SCALE
» SWIPL PRIMARY
DEM. FULL-SCALE
AWT SYSTEM
LAND
DISPOSAL
(NON-STRUCT)
DEM. FULL-SCALE
MARSH LAND DISP (SW)
FEAS:LAND
DISP(CS/SW)
PILOT:
LAND DISP
DEM. FULL-SCALE
LAND DISP
BIOL
DEM. FULL-SCALE
• LAGOONS • HRTF
• CONT STAB • RBCfPIL.)
DUAL USE |
I»CONT STAB !
I '
I»FLUIDIZED BEDl
I I
DISINF
DEV/PILOT
• PATH/VIR DETECTION
•HI-RATE (MIX,CI02,03)
• ON-SITE GEN
DEM. FULL-SCALE
• CONV CI2(CS/SW)
• HI-RATE
•ON-SITE
• VIRUS DISINF
•CARCINOGENIC RES
Figure 21. Treatment
-------
Ammonia removal (P-12 and advanced physical-
chemical-adsorption systems (81) have also
been developed and tested at the pilot
level. Physical processes have shown
importance for stormwater treatment
because of their adaptability to automated
operation, rapid startup and shut-down
characteristics, high-rate operation, and
very good resistance to shock loads.
A microstrainer is conventionally
designed for polishing secondary sewage
plant effluent at an optimum rate of
approximately 10 gpm/sg. ft. Tests on a
pilot microscreening unit of 23 micron
aperture in Philadelphis have shown that
at high influx rates of 25-30 gpm/ sg. ft.,
suspended solids removals in combined
overflows as high as 90% can be achieved
(34, 78, 105) . Comparison of three
different fine screens is continuing at
Syracuse, NY (P-2) .
A study in Cleveland (35) showed high
potential for treating combined sewer
overflows by in-pipe coagulation-filtration
using anthrafilt and sand in a 7 foot deep
bed. With the high loadings of 16 to 32
gpm/sg. ft. surface area, removal of solids
was effectively accomplished throughout
the entire depth of filter column. Test
work showed suspended solids removal up to
and exceeding 90 percent and BOD removals
in the range of 60 to 80 percent.
Substantial reductions, in the order of
30 to 80 percent of phosphates, can also
be obtained. A large-scale high-rate
filtration unit in New York City is being
evaluated for the dual-treatment of dry
and wet-weather flows (P-39) .
Results from a 5.0 mgd screening and
dissolved-air flotation demonstration pilot
plant in Milwaukee (20), indicate that
greater than 70 percent removals of BOD
and suspended solids are possible. By add-
ing chemical coagulants, 85 to 97 percent
phosphate reduction can be achieved as an
additional benefit. Based on these find-
ings two full-scale prototypes (20 and 40
mgd) have been demonstrated in Racine, WI
(P-23) .
Land Disposal
As previously discussed, the use of
marshlands for disposal of stormwater has
been demonstrated in Minnesota. The
feasibility of land disposal of raw CSO
has also been investigated (161). Because
of the cost of collection and transportation
and large land requirements this concept
does not appear feasible. Land disposal
of CSO sludges, liquid or dewatered,
appears feasible and promising for
ultimate sludge disposal; however, further
investigation in this area is required.
Biological Treatment
The following biological processes
have been demonstrated: contact stabili-
zation (117), high-rate trickling
filtration (95), rotating biological
contactors (106), and lagoons (108, 30).
The processes have had positive evaluation,
but with the exception of long term
storage lagoons, must operate conjunctively
with DWF plants to supply biomass, and
require some form of flow equalization.
Disinfection
Because disinfectant and contact
demands are great for storm flows, research
has centered on high-rate applications by
mixing and more rapid oxidants, i.e.,
chlorine dioxide (CIO2) and ozone (03); and
on-site generation (149, 31, 34, 78, 94,
105, 119). A continuing effort in Syracuse,
NY (P-2) will involve viral disinfection
and carcinogenic chlorine residual compound
studies.
Treatment Process Performance
Treatment process performance in terms
of design influx rate (gpm/sq ft) and 6005
and suspended solids (SS) removal
efficiency is provided in Table 12. The
high-rate performance of the swirl, micro-
strainer, filter, and dissolved air
flotation is apparent when compared to
sedimentation.
Sludge Solids
Due to the documented deleterious
effect of CSO on the quality of receiving
waters, WWF sludge handling and disposal
has been given less emphasis previously in
concession to the problems of treating the
combined overflow itself. Sludge handling
and disposal should be considered an
integral part of CSO treatment because it
significantly affects the efficiency and
cost of the total waste treatment system.
423
-------
TABLE 12 - WET-WEATHER TREATMENT PLANT PERFORMANCE DATA
Device
Primary
Secondary
Control Alternatives
a,b
Swirl Concentrator
c
Microstrainer
d
High-Rate Filtration
d
Dissolved Air Flotation
e
Sedimentation
Representative Performance
Contact Stabilization
g
Physical-Chemical
Representative Performance
Design Loading
Rate
(gpm/ft2)
60
20
24
2.5
0.5
Removal Efficiency (%)
BOD5
25-60
40-60
60-80
50-60
25-40
40
75-88
85-95
85
SS
50
70
90
80
55
60
90
95
95
Field, 197*6 (R-16)
DSullivan, 1974 (101)
CMaher, 1974 (105)
Lager and Smith, 1974 (102); w/chem. add.; hi-rate filter including pre-screens
a
"Performance data based on domestic wastewater treatment
fAgnew, et al., 1975 (117)
Esimate based on performance of these units for domestic wastewater (102)
Flow characterization studies show that the
annual quantity of CSO solids is at least
equal to and in most cases greater than
solids from DWF. For example, 29% of the
sewered population in the U.S. is served
by combined sewers. This represents
a service area of 3xlO& acres. Assuming
an average yearly rainfall of 36 in. and
50% of the runoff resulting in an overflow,
the yearly volume of CSO in the U.S. would
be 1.5x10^2 gal. The corresponding average
yearly volume of sludge resulting from
treatment of all CSO nationwide is estimated
at 41xl09 gal or 2.8% of the volume tested.
The average solids content of this sludge
would be about 1%. In comparison, an
average yearly volume of dry weather sludge
of 35xl09 gal may be expected from the same
service area. Consequently, if nationwide
CSO treatment was instituted there would
be a problem equal to or greater than
the problem there now is with municipal
sludge.
The chronology of the Program's WWF
sludge/solids technological advancement
is contained in Figure 22. The need for
defining the problem was recognized and,
in FY 73, a contract was awarded (P-21)
to characterize and preliminarily
quantify CSO sludge/solids and perform
treatability studies. Sludge handling/
disposal techniques are also being
evaluated and a nationwide assessment of
the sludge problem has been conducted
(P-24) . As part of this assessment, the
"impacts" of the following alternatives
424
-------
PRE-FY 76
FY 76
FUTURE
WWF SLUDGE/
SOLIDS CHAR./QUANT.
DESK-TOP ANALYSIS OF
HANDLING/DISPOSAL
TECHNIQUES
TREATABILITY STUDIES
(BENCH)
PILOT STUDIES OF
CONVENTIONAL TECH.
(CENT.;ANAER.DIG.)
NATIONWIDE ASSESS. OF
WWF SLUDGE PROBLEM
EVAL. IMPACTS OF WWF
SLUDGES/SOLIDS ON DWF PL.
EVAL. ALTERNATIVE SLUDGE/
SOLIDS HANDLING/DISPOSAL
TECHNIQUES
MOP FOR WWF SLUDGE/
SOLIDS HANDLING/DISPOSAL
DEM. NEW SLUDGE/SOLIDS
HANDLING TECH.(SWIRL)
DEM. DISPOSAL OF WWF
SLUDGES TO LAND
(ALSO RAW CSO/SW)
Figure 22. Sludge/Solids
-------
are being considered: bleed-back of the
sludge to the municipal dry weather treat-
ment plant, handling the sludges with
parallel facilities at the dry weather
plant, handling the sludges at the site
of CSO treatment, and land disposal of
either untreated or treated sludges.
Sludge: Products (Table 13)
Two reports are presently available
(159, 161). The first covers the
characterization, treatability, and
quantification of CSO sludges and solids
and the second is a "rough cut" at
assessing the impact of handling and
disposal.
TABLE 13 - SLUDGE/SOLIDS: PRODUCTS
Characterization and Quantification of
CSO Sludges and Solids (Draft report
available) (159).
WWF Sludge/Solids Impact Assessment
(Preliminary report available) (161).
WWF Sludge/Solids Treatability Studies
(159).
The characterization, quantification,
and treatability evaluation of sludges
from separate stormwater will be done in
the future.
Integrated Systems
By far the most promising and common
approaches to urban stormwater management
involve the integrated use of control and
treatment with an areawide multidisciplinary
perspective. When a single method is not
likely to produce the best possible answer
to a given pollution situation, various
treatment and control measures may be
combined for maximum flexibility and
efficiency.
Integrated systems is divided into
(1) Storage/Treatment, (2) Dual Use
WWF/DWF Facilities, and (3) Control/
Treatment/Reuse (Figure 23).
Storage/Treatment
Where there is storage, there is
treatment by settling, pumpback to the
municipal works, and sometimes disinfection-
and treatment, which receives detention,
provides storage. In any case, the break-
even economics of supplying storage must
be evaluated when treatment is considered
(35) . The program has demonstrated all
of these storage-treatment concepts on a
full-scale basis (15, 18, 25, 26, 29, 30,
40, 72, 102, 108, 114, 118, 134, 146, 147,
154, P-10, P-37).
Dual Use, WWF/DWF Facilities
The concept of dual use is — maximum
utilization of wet-weather facilities
during nonstorm periods and maximum utili-
zation of dry-weather facilities during
storm flows for total system effectiveness.
The program has demonstrated the dual use
of high-rate trickling filters (95) ,
contact stabilization (117), and equali-
zation basins (107, 114). On a pilot
scale the Program has evaluated advanced
physical-chemical treatment (81); and is
in the process of demonstrating large-
scale, high-rate filtration (P-39).
It should also be mentioned that
combined sewers themselves are dual use
systems.
Control/Treatment/Reuse
The sub-category, "Control/Treatment/
Reuse" is a "catch-all" for all integrated
systems. As the prime consideration, it
is reasonable to apply the various non-
structural and land management techniques
to reduce downstream loads and treatment
costs.
Previous projects have evaluated the
reuse of stormwater runoff for aesthetic,
recreastional, and subpotable and potable
water supply purposes (62, 79). In Mt.
Clemens, MI, a series of three "lakelets"
has been incorporated into a CSO treatment-
park development (114). Treatment and
disinfection is being provided so that
these lakes are aesthetically pleasing
and allow for recreation and reuse for
irrigation. Other projects have shown
the feasibility of reclaiming stormwater
(3, 39).
The previously mentioned Houston
project (P-16) is focusing on how a
"natural drainage system" can be integrated
into a resue scheme for recreation and
aesthetics.
426
-------
PRE-FY76
FUTURE
STORAGE/
TREAT
DUAL USE,
WWF/DWF
FAC
DEM. STORAGE W/
• PUMP-BACK
• SED. IN STORAGE
• STORAGE/TREAT LAGOON
• DISINF.
• BREAK-EVEN ECON.
W/TREAT
DEM. TREAT
HRTF (F/S)
CONT STAB (F/S)
HI-RATE FILT(F/S)
P-C(AWT,PILOT)
DEM. EQUALIZATION
(ROHNERT PK.)
COMBINED SEWERS
DEM. TREAT
• PHY-BIOL
• DISS AIR FLOT
• MICROSCREENS
DEM. STORAGE
• DWF/WWF
W/EFFL POLISH
CONT/TREAT/
REUSE
• LAND MGMT/TREAT
• TREAT-PK
• STORAGE-TREAT
LAKELETS
Figure 23. Integrated Systems
DEM. STOR-TREAT-
RECHARGE
427
-------
Integrated Systems: Products
The specific outputs from the
integrated systems work have been pre-
dominantly in the form of demonstrations,
documented by final reports. The previously
referenced SOTA Assessment Report (102)
summarizes the work in this area and ties
it into wastewater management systems
planning, design, and program implemen-
tation. Specific demonstration products
are classified into main and complementary
units for interrelating storm flow
devices and unit processes and interfacing
with dry-weather facilities. In the future
it is important to evaluate storage used
for DWF and WWF along with secondary
effluent polishing.
TECHNICAL ASSISTANCE/TECHNOLOGY TRANSFER
The Technology Transfer area covers
the formal dissemination of Program find-
ings in the form of actual project reports,
films, journal papers, SOTA reports, and
manuals of practice and instruction. To
date the Program has published approximately
160 reports, and it is the intent here to
concentrate on the "user" type of document.
Significant Documents Completed
Reports generated by the program have
received widespread recognition both within
this country and abroad. Many have been
referenced by EPA headquarters and used
for 201/208 studies. Some of the more
significant documents are indicated in
Table 14. The first set of reports, item
No. 1, set the pace for EPA's Program by
identifying stormwater and combined sewer
overflow as major sources of water
pollution and provided a characterization
data base (Refs. see item 1, Table 14).
As previously mentioned, the manuals of
practice on infiltration/inflow (27, 28,
97) and regulators (23, 24), Nos. 3 and 4,
flagged two prime and basic problems leading
to fruitful countermeasure research and a
national emphasis on I/I control. Specific
research products coming out of the
regulator MOPs were the swirl (69, 93, 99,
101) and helical (132) devices — resul-
tant design manuals are listed as Nos.
5 and 6. Number 8 cites two instrumen-
tation reports (130, 133) for flow
analysis which have proven to be highly
useful to the engineering community,
including Construction Grants. An
assessment of the significant impacts of
highway deicing chemical use (67, 86) and
practicable MOPs on control through proper
salt storage and use (100, 104) are covered
by items 9 and 10. Nos. 11 through 18
relate to Approach and Solution Methodology,
the goal of the program. Item 19 refers to
two very important user' s manuals containing
relatively simple urban runoff assessment
planning methods (148, 153) which can be
applied to 201 and 208 studies; and item 20
cites the previously mentioned national
assessment of urban runoff control and
costs (157).
Significant Documents Anticipated (Table 15)
In the immediate future a construction
and OSM cost estimating manual (156) for CSO
storage and treatment will be released,
along with three other assessments: two on
WWF sludge handling, disposal, and impact
problems (159, 161) , and the other on
pathogens in stormwater (160).
Ongoing work will also lead to an
updated SOTA and a planning document pro-
viding guidance and examples for total
municipal studies (P-5) and a refined
SWMM user's manual (P-53).
CAPITAL COSTS COMPARISON FOR STORM AND
COMBINED SEWER CONTROL/TREATMENT
Table 16 shows a capital cost compari-
son for various SCS control and treatment
methods.
Sewer separation is very costly with a
national average of $20,000/ac (2, 102).
In-system control storage costs were found
to be as low as $0.02 and $0.25/gal for
Detroit and Seattle, respectively (R-6d,
111). These figures represented l/10th
the cost for large off-line facilities, and
l/25th the costs for separation in Detroit
and Seattle, respectively. Off-line storage
varies from $0.03 to $4.75/gal depending on
whether earthen or concrete basins are
employed (102).
Per acre costs can only be given in
wide ranges since they significantly vary
with climate, receiving water, terrain,
degree of urbanization, sewer network con-
figuration, etc. Per capita and per acre
unit costs may be applicable for gross
estimating; but it is best to fix unit
costs per gallon for storage and per mgd
for treatment as design factors for the
user engineer confronted with site-specific
conditions.
428
-------
TABLE 14 - SIGNIFICANT DOCUMENTS COMPLETED
. Assessment - Problems of CSO/SW (2, 20, 34, 35, 41, 47, 51, 53, 54, 59, 60, 63, 65,
67, 73, 81, 82, 83, 88, 102, 112, 123, 124, 127, 128, 143, 149)
2. CSO/SW Seminar Reports (6, 40, 96, 140a)
3. MOP - I/I Prevention and Correction (27, 28, 97)
4. MOP - Regulation and Management (23, 24)
5. Design Manuals - Swirl: Regulator/Degritter/Erosion Control (69, 93, 99, 101)
6. Design Manual - Helical Regulator/Separator (132)
7. Assessments - Sources/Impacts of Urban Runoff Pollution (157, 164, 127, 88, 128, 73)
8. Assessments - Sampling/Flowrate Measurement (133, 130)
9. Assessment - Impact of Deicing (67, 86)
10. MOP's - Deicing Chemical Usage/Storage & Handling (100, 104)
11. Assessment - SOTA Urban Stormwater Management Technology (102, 111, 137)
12. User's Manuals - SWMM, Version I and II (44, 116)
13. Course Manual - SWMM Application (125)
14. SOTA - Urban Water Management Modeling (136)
15. MOP - Determination of Flowrates/Volumes (140)
16. Assessment/MOP - Stormwater Models (141)
17. MOP - Procedures for Stormwater Characterization/Treatment Studies (145)
18. MOP's - Sediment & Erosion Control (68, 70, 168, 169)
19. User's Manuals - Simplified Urban Runoff Planning Models/Tools (148, 153)
20. Assessment - Nationwide Stormwater/Characterization/Impacts/Costs (157)
TABLE 15 - SIGNIFICANT DOCUMENTS ANTICIPATED
- Estimating Manual - CSO Storage and Treatment Costs (156)
- User's Manual - SWMM Version III
- Assessments - WWF Sludge Handling/Disposal Problems/Impacts (159/161)
- Assessment - Pathogens in Stormwater and Combined Sewer Overflow
(160)
- SOTA/Planning Guide - Update Storm and Combined Sewer Overflow
Management and Treatment/Total Approach Methodology
- Design Manual - Swirl: Primary Treatment
- MOP - I/I Analysis, Prevention and Control
- Instruction Manual - Storm and Combined Sewer Overflow Technology
Post FY 76
- MOP - Pollution Control from Construction Activities
- MOP - Refined Solution Methodology
- MOP - Land Management
- Design Manual - Storage Facilities
- Consolidated Design Text - Swirl and Helical
429
-------
Table 16. Typical Capital Costs for SCS Control/Treatment (ENR 2000)
COMPONENT DEVICES
SEPARATION
STORAGE
• IN-LINE
• OFF-LINE
-EARTHEN
-CONCRETE TANKS
TREATMENT
• PHYSICAL W&W/O CHEMICALS
-FINE SCREENING/MICROSTRAINING
-SEDIMENTATION
-HI-RATE FILT
-DISS AIR FLOAT
-SWIRL
• BIOLOGICAL
-CON. STAB/TRICK. FILTER
-LAGOONS
• PHYSICAL-CHEMICAL SYSTEMS
• DISINFECTION
-CONVENTIONAL
-HI-RATE(STATIC MIXING)
INTEGRATED SYSTEMS
• STORAGE/TRMT/REUSE
-TREATMT-PARK CONCEPT
LAND MANAGEMENT
• STRUCTURAL
-DIVERSION BERMS
• NON-STRUCTURAL
-STREET CLEANING
J/GAL
0.02 0.25
(DETROIT) (SEATTLE)
0.03-0.26
1.00-4.75
S/MGD
5,000/12,000
10,000-50,000
70,000
40,000
8,000 (SYRACUSE)
2,000 (LANCASTER)
80,000
17,000
150,000-2*106
1,500
900
t*106(KING«AN LAKE)
17,000(«T. CLEMENS)
S/ACRE
10,000 (SEATTLE)
6,500 (DES MOINES)
32,000 (CLEVELAND)
20,000-NATIONAL AVE.
400 (SEATTLE)
250 (MINNEAPOLIS)
7,000 (JAMAICA.NYC)
2,000/13,000
3,500-6,500
10,000
6,500 (MILWAUKEE)
SOO(SYRACUSE)
SOO(LANCASTER)
1,700
5,000
10,000(KINGMAN LAKE)
5,000(MT. CLEMENS)
160
0.7
430
-------
These data are based on a limited
number of specific projects thus they
represent only a range of placement. In
extrapolating these costs into master
plan systems for cities, the totals
frequently approach $500 to $1,000 per
capita.
Physical treatment costs range
between $2,000 and $35,000/mgd; whereas
physical with chemical treatment
varies between $35,000 and $80,000/mgd.
Biological treatment ranges between
$17,000 and $80,000/mgd depending on
whether land is available for lagooning
or if contact stabilization or trickling
filtration (102) is resorted to. As can
be seen from the table, costs for the
swirl at $2,000/mgd and $500/acre (P-4)
are considerably lower than other forms
of treatment installation.
Preliminary figures for incorporating
land management techniques show a definite
cost-effectiveness benefit.
It must be mentioned that the
various alternatives offer different
degrees of removal which will have a
significant bearing on the selection
process.
SEATTLE: IN-LINE STORAGE IS COST-EFFECTIVE
A case study illustrating cost-
effectiveness by Seattle's flow routing
approach is worthwhile discussing (98,
140a).
Costs
The Seattle in-line storage system
covering 13,250 acres costs $5.3 million
or $400 per acre as opposed to tens of
thousands of dollars per acre for other
alternatives. A specific Seattle study
revealed $10,000 per acre for separation.
The low cost is attributed to a quasi-
structural system which takes advantage
of the existing combined sewer network;
and control gates installed at
strategic points only. The system is
highly signal and computer oriented with
minimal hardware requirements. In fact,
one-half the costs were for computers
and related software. Of course, in-line
storage is site specific since implemen-
tation of the concept requires a relatively
large and flat existing combined system.
Pollutant Reduction
Overflow and pollutant reduction from
12 major overflow points averaged 55%
and 68%, respectively. Also, 90% of
the overflow volume was reduced by
experimental automatic control.
Effectiveness
Effectiveness of the system is
proven by a one to two mg/1 D.O. increase
and a 50% coliform reduction in the
receiving water.
DBS MOINES: CONTROL COSTS
VERSUS-D.O. VIOLATIONS
Based on a study for the City of
Des Moines (157) using a simplified
receiving water model, four control
alternatives were compared considering
cost and true effectiveness in terms of
frequency of D.O. standard violations.
As Table 17 depicts, 25% BOD removal
of WWF coupled with secondary treatment
of DWF results in slightly higher D.O.
levels in the receiving water than tertiary
treatment and no control of urban runoff.
The annual cost of 25% BOD removal for WWF
is 10% of the cost for tertiary treatment.
However, existing DWF treatment facilities
exhibit a comparable effect to these two
options at no additional cost. However,
significant increase in the minimum D.O.
levels of the Des Moines River is obtained
by 75% BOD removal of WWF with the annual
cost of this level of control being lower
than the cost of tertiary treatment. The
application to Des Moines demonstrated
clearly the overwhelming effect of urban
runoff pollution on critical D.O. concen-
trations. The cost-effectivenss of various
treatment alternatives can be determined
realistically only by a continuous
analysis of the frequency of water quality
violations.
In the selection of the "best"
control strategy, other factors that may
become important are: (1) recovery of
receiving waters from shock loads caused
by runoff, (2) local and regional water
quality goals, and (3) public willingness
to pay the costs associated with each level
of control.
431
-------
TABLE 17 - DBS MOINES: CONTROL COSTS VERSUS VIOLATIONS OF DO STANDARD (4 PPM)
Options
1. DWF Tertiary Treatment
2. WWF 25% BOD Removal
3. WWF 75% BOD Removal
4. DWF Secondary Trt Only
Total Annual Cost
(S/yr)
6.3M
0.6M
4.0M
0
% of Precipitation Events
Violating Standard
40
30
3
42
432
-------
REFERENCES AND BIBLIOGRAPHY
Bibliography of Urban Runoff Control Program Reports
Ongoing Urban Runoff Pollution Control Projects ("P" Numbers)
Other Urban Runoff Pollution Control Program References ("R" Numbers)
433
-------
BIBLIOGRAPHY OF URBAN RUNOFF POLLUTION CONTROL PROGRAM REPORTS
Ref.
No.
Report Number
Title/Author
Source
1. 11020—09/67
2. 11020—12/67
3. 11020—05/68
4. 11020—06/69
5. 11020—10/69
6. 11020—03/70
11020—02/71
8. 11020DES06/69
9. 11020DGZ10/69
Demonstrate the Feasibility of the NTIS ONLY
Use of Ultrasonic Filtration in PB 201 745
Treating the Overflows from Combined
and/or Storm Sewers: by Accoustica
Assoc., Inc., Los Angeles, CA
Problems of Combined Sewer Facilities NTIS ONLY
and Overflows-!967: by AmericanPB 214 469
Public Works Assoc., Chicago, IL
Feasibility of a Stabilization- NTIS ONLY
Retention Basin in Lake Erie at PB 195 083
Cleveland, OH: by Havens and Emerson,
Cleveland, OH
Reduction in Infiltration by Zone NTIS ONLY
Pumping: by Hoffman and Fiske, PB 187 868
Lewiston, ID
Crazed Resin Filtration of Combined NTIS ONLY
Sewer Overflows: by Hercules, Inc., PB 187 867
Wilmington, DE
*Combined Sewer Overflow Seminar NTIS
Papers: by Storm and Combined Sewer PB 199 361
Pollution Control Branch, Division of
Applied Science and Technology, FWQA,
Washington, DC
*Deep Tunnels in Hard Rock: by College NTIS
of Applied Science and Engineering PB 210 854
and University Extension, University
of Wisconsin, Milwaukee, WI
Selected Urban Water Runoff Abstracts:NTIS ONLY
by The Franklin Institute, Phila-PB 185 314
del phi a, PA
Design of a Combined Sewer Fluidic NTIS ONLY
Regulator: by Bowles EngineeringPB 188 914
Corp., Silver Spring, MD
*Copies may be obtained from EPA Storm & Combined Sewer Section,
Edison, NJ 08817
Note: Number in left margin corresponds to reference numbers cited in report
text.
434
-------
Ref.
No. Report Number
Title/Author
Source
10. TI020DH006/72
11. 11020DIG08/69
12. 11020DIH06/69
13. 11020DN008/67
14. 11020DN003/72
15. 11020DWF12/69
16. 11020EK010/69
17. 11020EXV07/69
18. 11020FAL03/71
19. 11020FAQ03/71
20. 11020FDC01/72
21. 11020FKI01/70
22. 11022DEI05/72
*Copies may be obtained
Edison, NJ 08817
*Ground Water Infiltration and
NTIS
Internal Seal ings of Sanitary Sewers, PB 212 267
Montgomery County, OH: by G.E. Cronk
Polymers for Sewer Flow Control: by NTIS ONLY
The Western Co., Richardson, TX PB 185 951
Improved Sealants for Infiltration NTIS ONLY
Control: by The Western Company.PB 185 950
Richardson, TX
Feasibility of a Periodic Flushing NTIS ONLY
System for Combined Sewer Cleansing: PB 195 223
by FMC Corp., Santa Clara, CA
*A Flushing System for Combined Sewer NTIS
Cleansing: by Central EngineeringPB 210 858
Laboratories, FMC Corp., Santa
Clara, CA
Control of Pollution by Underwater NTIS ONLY
Storage: by Underwater Storage, Inc., PB 191 217
Silver, Schwartz, Ltd., Joint Ven-
ture, Washington, DC
Combined Sewer Separation Using NTIS ONLY
Pressure Sewers: by American Society PB 188 511
of Civil Engineers, Cambridge, MA
Strainer/Filter Treatment of Combined NTIS ONLY
Sewer Overflows: by Fram Corporation, PB 185 949
East Providence, RI
*Evaluation of Storm Standby Tanks, NTIS
Columbus, OH: by Dodson, Kinney & PB 202 236
Lindblom, Columbus, OH
*D1spatching Systems for Control of NTIS
Combined Sewer Losses: by Metro^PB 203 678
Sewer Board, St. Paul, MN
Screening/Flotation Treatment of GPO ONLY
Combined Sewer Overflows: by The
Ecology Division, Rex Chainbelt, Inc.,
Milwaukee, WI
Dissolved-Air Flotation Treatment of NTIS ONLY
Combined Sewer Overflows: by Rhodes PB 189 775
Corp., Oklahoma City, OK
*Sewer Bedding and Infiltration Gulf NTIS
Coast Area: by J.K.Mayer. F.W.Mac PB 211
Donald, and S.E.Steimle; Tulane Univ.,
New Orleans, LA
from EPA Storm & Combined Sewer Section,
435
282
-------
Ref.
No. Report Number
Title/Author
Source
23. 11022DMU07/70
24. 11022DMU08/70
25. 11022DPP10/70
26. 11022ECV09/71
27. 11022EFF12/70
28. 11022EFF01/71
*Combined Sewer Regulator Overflow
Facilities: by American Public Works
Assoc., Chicago, IL
GPO ONLY
29. 11022ELK12/71
30. 11023—08/70
31. 11023DAA03/72
32. 11023DPI08/69
33. 11023DZF06/70
34. 11023EV006/70
35. 11023EYI04/72
*Copies may be obtained
Edison, NJ 08817
*Combined Sewer Regulation and Manage- NTIS
ment A Manual of Practice: by AmericanPB 195 676
Public Works Assoc., Chicago, IL
*Combined Sewer Temporary Underwater NTIS
Storage Facility: by Mel par, Falls PB 197 669
Churcfi, VA
Underwater Storage of Combined Sewer NTIS ONLY
Overflows: by Karl R. Rohrer Assoc., PB 208 346
Inc., Akron, OH
Control of Infiltration and Inflow NTIS ONLY
into Sewer Systems: by American PB 200 827
Public Works Assoc., Chicago, IL
*Prevention and Correction of Exces- NTIS
sive Infiltration and Inflow intoPB 203 208
Sewer Systems-A Manual of Practice:
by American Public Works Assoc.,
Chicago, IL
Maximizing Storage in Combined Sewer NTIS ONLY
Systems: by Municipality of Metro-PB 209 861
poll tan Seattle, WA
*Retention Basin Control of Combined NTIS
Sewer Overflows: by SpringfieldPB 200 828
Sanitary District, Springfield, IL
*Hypochlorite Generator for Treatment NTIS
of Combined Sewer Overflows: "by PB 211 243
Ionics, Inc., Watertown, MA
Rapid-Flow Filter for Sewer Over- NTIS ONLY
flows: by Rand Development Corp., PB 194 032
Cleveland, OH
*Ultrasonic Filtration of Combined NTIS
Sewer Overflows: by American Process PB 212 421
Equipment Corp., Hawthorne, CA
*Microstraining and Disinfection of NTIS
Combined Sewer Overflows: by Cochrane PB 195 674
Div., Crane Co., King of Prussia, PA
*High Rate Filtration of Combined NTIS
Sewer Overflows: by Ross Nebolsine, PB 211 144
P.J.Harvey, and Chi-Yuan Fan, Hydro-
technic Corp., New York NY
from EPA Storm & Combined Sewer Section,
436
-------
Ref.
No. Report Number
Title/Author
Source
36. 11023FDB09/70
37. 11023FDD03/70
38. 11023FDD07/71
39. 11023FIX08/70
40. 11024—-06/70
41. 11024DMS05/70
42. 11024DOC07/71
43. 11024DOC08/71
44. 11024DOC09/71
45. 11024DOC10/71
46. 11024DOK02/70
*Chemical Treatment of Combined Sewer NTIS
Overflows: by Dow Chemical Company. PB 199 070
Midland, MI
Rotary Vibratory Fine Screening of NTIS ONLY
Combined Sewer Overflows: by Cornell PB 195 168
Howl and, Hayes and Merryfield, Cor-
vallis, OR
*Dempnstration of Rotary Screening for NTIS
Combined Sewer Overflows: by City of PB 206 814
Portland, Dept. of Public Works,
Portland, OR
Conceptual Engineering Report- NTIS
Kingman Lake Project:"by RoyT. PB 197 598
Weston, West Chester, PA
*Combined Sewer Overflow Abatement NTIS
Technology: by Storm and Combined PB 193 939
Sewer Pollution Control-Branch,
Division of Applied Science and
Technology, FWQA, Washington, DC
*Engineering Investigation of Sewer NTIS
Overflow Problems: by Hayes. Seay. PB 195 201
Mattern and Mattern, Roanoke, VA
*Storm Water Management Model, NTIS
Vol. 1. Final Report: by Metcalf & PB 203 289
Eddy Engineers, Palo Alto, CA
Storm Water Management Model. Vol. NTIS ONLY
II. Verification and Testing: by ~ PB 203 290
Metcalf & Eddy Engineers, Palo AHo.CA
Storm Water Management Model. Vol. NTIS ONLY
III, User's Manual: by Metcalf &PB 203 291
Eddy Engineers, Palo Alto, CA
Storm Water Management Model, Vol. IV NTIS ONLY
Program Listing: by Metcalf & EddyPB 203 292
Engineers, Palo Al to., CA
*Proposed Combined Sewer Control by
Electrode Potential: by Merrimack
College, Andover, MA
NTIS
PB 195 169
47. 11024DQU10/70 *Urban Runoff Characteristics: by
*Copies may be obtained
Edison, NJ 08817
NTIS
University of Cincinnati, Cincinnati, PB 202 865
OH
from EPA Storm & Combined Sewer Section,
437
-------
Ref.
No. Report Number
Title/Author
Source
48. 11024EJC07/70
49. 11024EJC10/70
50. 11024EJC01/71
51. 11024ELB01/71
52. 11024EQE06/71
53. 11024EQG03/71
54. 11024EXF08/70
55. 11024FJE04/71
56. 11024FJE07/71
57. D E L E T E
58. 11024FKJ10/70
59. 11024FKM12/71
*Copies may be obtained
Edison, NJ 08817
Selected Urban Storm Water Runoff NTIS ONLY
Abstracts. July 1968-June 1970: by PB 198 228
The Franklin Institute Research Lab.,
Philadelphia, PA
*Selected Urban Storm Water Runoff NTIS
Abstracts, first Quarterly Issue: PB 198 229
by The Franklin Institute Research
Lab., Philadelphia, PA
*Selected Urban Storm Water Runoff NTIS
Abstracts, Second Quarterly Issue: PB 198 312
by The Franklin Institute Research
Lab., Philadelphia, PA
*Storm and Combined Sewer Pollution NTIS
Sources and Abatement. At!anta,~GA: PB 201 725
by Black, Crow and tiasness, inc.,
Atlanta, GA
impregnation of Concrete Pipe: by GPO
Southwest Research Institute,
San Antonio, TX
Storm Water Problems and Control in NTIS ONLY
Sanitary Sewers. Oakland & Berkeley", PB 208 815
CA: by Metcalf & Eddy Engineers,
PFlo Alto, CA
*Combined Sewer Overflow Abatement NTIS
Alternatives, Washington, DC: by~Roy PB 203 680
F- Weston, Inc., West Chester, PA
*Selected Urban Storm Water Runoff GPO
Abstracts, Third Quarterly Issue:'
by Franklin Institute Research Lab.,
Philadelphia, PA
*Selected Urban Stormwater Runoff GPO
Abstracts July 1970 -June 1971: by
The Franklin Institute Research Lab.,
Philadelphia, PA
D DELETED
*In-Sewer Fixed Screening of Combined NTIS
Sewer Overflows: by Envirogenics Co., PB 213 118
Div. of Aerojet General Corp.,
El Monte, CA
Urban Storm Runoff and Combined NTIS ONLY
Sewer Overflow Pollution. SacTeTmento. PB 208 989
CA: by Envirogenics Co., Div. of
Aerojet General Corp., El Monte, CA
from EPA Storm & Combined Sewer Section,
438
-------
Ref.
No. Report Number
Title/Author
Source
60. 11024FKN11/69
61. 11024FLY06/71
62. 11030DNK08/68
63. 11030DNS01/69
64. 11034DUY03/72
65. 11034FKL07/70
66. 11034FLU06/71
67. 11040GKK06/71
68. 15030DTL05/70
*Stream Pollution and Abatement from
Combined Sewer Overflows, Bucyrus.~
OH.: by Burgess and N1 pie, Ltd.,
Columbus, OH
*Heat Shrinkable Tubing as Sewer
Pipe Joints: by The Western Co. of
North America, Richardson, TX
The Beneficial Use of Stormwater: by
Hittman Associates, Inc., Baltimore,
MD
Mater Pollution Aspects of Urban
Runoff: by American Public Works
Assoc., Chicago, IL
•"Investigation of Porous Pavements
for Urban Runoff Control: by
E. Thelen, W.C.Grover, A.J.Hoi berg,
and T.I.Haigh, The Franklin Institute
Research Lab., Philadelphia, PA
Stormwater Pollution from Urban Land
Activity:by AVCO Economic Systems
ivity:
JTTwa
NTIS
PB 195 162
NTIS
PB 208 816
NTIS ONLY
PB 195 160
NTIS ONLY
PB 215 532
NTIS
PB 227 516
NTIS ONLY
PB 195 281
Corp., Washington, DC
*Hydraulics of Long Vertical Conduits GPO
and Associated Cavitation: by Uni-
versity of Minnesota, Minneapolis, MN
*Environmenta1 Impact of Highway NTIS
Deicing: by Edison Water Quality PB 203 493
Laboratory, EPA, Edison, NJ
Urban Soil Erosion and Sediment NTIS ONLY
Control: by National Association of PB 196 111
Counties Research Foundation,
Washington, DC
69. EPA-R2-72-008
70. EPA-R2-72-015
*The Swirl Concentrator as a Combined
Sewer Overflow Regulator Facility:
by American Public Works Assoc.,
Chicago, IL
Guidelines for Erosion and Sediment
Control Planning and Implementation:
by the Dept. of Water Resources,
State of MD, and Hittman Assoc., Inc.,
Columbia, MD
*Copies may be obtained from the EPA Storm and Combined Sewer Section,
Edison, NJ 08817
GPO $2.25
EP 1.23/2:72-008
NTIS
PB 214 687
NTIS ONLY
PB 213 119
439
-------
Ref.
No. Report Number Title/Author Source
71 EPA-R2-72-068 *Storm Sewer Design-An Evaluation of GPO
the RRL Method: by J.B.Stall and EP 1.23/2:72-068
M.L.Tierstriep, Illinois State Water NTIS
Survey, University of Illinois PB 214 134
Urbana, IL
72 EPA-R2-72-070 *Storage and Treatment of Combined GPO
Sewer Overflows; by the City of EP 1.23/3:72-070
Chippewa Falls, WI NTIS
PB 214 106
73. EPA-R2-72-081 *Uater Pollution Aspects of Street GPO
Surface Contaminants: by J.D.Sartor EP 1.23/2:72-081
and G.B.Boyd, URS Research Co., NTIS
San Mateo, CA PB 214 408
74. EPA-R?-72-082 *Feasibility Study of Electromagnetic GPO
Subsurface Profiling: by R.M. Morey EP 1.23/2:72-082
and W.S. Harrington, Jr., Geophysical NTIS
Survey Systems, Inc., North BillericaPB 213 892
MD
75. EPA-R2-72-091 *A Pressure Sewer System Demonstration•GPO
by I.G.Carcich, et al, New York State EP 1.23/2:72-091
Department of Environmental Conserva- NTIS
tion, Albany, NY PB 214 409
76. EPA-R2-72-125 *A Search: New Technology for Pave- GPO
ment Snow and Ice Control: byEP 1.23/2:72-125
D.M. Murray and M.R. Eigerman, NTIS
ABT Associates, Inc., Cambridge, MD PB 221 250
77. EPA-R2-72-127 *Selected Urban Stormwater Runoff GPO
Abstracts. July 1971-June 1972: EP 1.23/2:72-127
by D.A. Sandoski, The Franklin In- NTIS
stitute Research Lab., Philadelphia, PB 214 411
PA
78. EPA-R2-73-124 Microstraining and Disinfection of GPO
Combined Sewer Overflows-Phase II: EP 1.23/2:73-124
by G.E. Glover, G.R. Herbert, Crane NTIS
Company, King of Prussia, PA PB 219 879
79. EPA-R2-73-139 *The Beneficial Use of Stormwater: GPO
by C.W. Mallory, Hittman Associates, EP 1.23/2:73-139
Columbia, MD NTIS
PB 217 506
80. EPA-R2-73-145 *A Thermal Wave Flowmeter for GPO
Measuring Combined Sewer Flows: EP 1.23/2:73-145
by P. Esnleman and R. Blase, Hydro- NTIS
space Challenger, Inc., Rockville, MD PB 227 370
*Copies may be obtained from EPA Storm and Combined Sewer Section,
Edison, NJ 08817
440
-------
Ref.
No.
Report Number Title/Author
Source
81. EPA-R2-73-H9 Physical-Chemical Treatment of Com-
bined and Municipal Sewage: by A.J.
Shuckrow, et al., Pacific NW Lab.,
Battelle Memorial Institute,
Rich!and, WA
82. EPA-R2-73-152 *Cpmbined Sewer Overflow Study for
the Hudson River Conference: by A.I.
Mytelka, et al., Interstate Sanita-
tion Commission, New York, NY
(jointly sponsored by Office of En-
forcement & General Council and
Office of Research & Monitoring, EPA)
83. EPA-R2-73-170 *Cgmbined Sewer Overflow Abatement
Plan, Des Moines, IA: by P.L.Davis,
et al., Hennington, Durham, and
Richardson, Inc., Omaha, NE
*Flow Augmenting Effects of Additives
on Open Channel Flows: by C. Derick
and K. Logie, Columbia Research Inc.,
Gaithersburg, MD
*Temporary Detention of Storm and
Combined Sewage in Natural Und'eT-
84. EPA-R2-73-238
85. EPA-R2-73-242
86. EPA-R2-73-257
ground Formations:
Paul, St. Paul, MN
by City of St.
87. EPA-R2-73-261
5. EPA-R2-73-283
88a EPA-600/2-73-002
Water Pollution and Associated
Effects from Street Salting: by
R.Field, H.E.Masters, A.N.Tafuri,
Edison Water Quality Research Lab.,
EPA, Edison, NJ and E.J.Struzeski,
EPA, Denver, CO
*An Assessment of Automatic Sewer
Flow Samplers: by P.E.Shelley and
G.W.Kirkpatrick, Hydrospace Challenger
Inc., Rockville, MD
*Toxic Materials Analysis of Street
Surface Contaminants: by R.E.Pitt and
G.Amy, URS Research Co., San Mateo,
CA
A Portable Device for Measuring Waste-
water Flow in Sewers: by Michael A.
Nawrocki, Hittman Associates, Inc.,
Columbia, MD
GPO
EP 1.23/2:73-149
NTIS
PB 219 668
GPO
EP 1.23/2:73-152
NTIS
PB 227 341
GPO
EP 1.23/2:R2-73-170
GPO
EP 1.23/2:73-238
NTIS
PB 222 911
GPO
EP 1.23/2:73-242
In-House
Report
NTIS
PB 222 795
GPO
EP 1.23/2:R2-73-261
NTIS
PB 223 355
GPO
EP 1.23/2:R2-73-283
NTIS
PB 224 677
GPO
EP 1.23/2:600/2-73-002
NTIS
PB 235 634
*Copies may be obtained from EPA Storm and Combined Sewer Section,
Edison, NJ 08817
441
-------
Ref.
No. Report Number Title/Author Source
89 EPA-660/2-73-035 Joint Construction Sediment Control GPO
Project: by B.C.Becker, et al..EP 1.23/2:660/2-73-035
Water Resources Administration, State NTIS
of Maryland PB 235 634
90 EPA-660/2-74-071 Programmed Demonstration for Erosion GPO
and_Sediment Control Specialist"EP 1.23/2:660/2-74-071
by T.R.Mills, et al., Water Resources
Administration, State of Maryland
91. EPA-660/2-74-072 Demonstration of the Separation and GPO
Disposal of Concentrated Sediments: EP 1.23/2:660/2-74-072
by M.A.Nawrocki, Hittman Associates,
Columbia, MD
92. EPA-660/2-74-073 An Executive Summary of Three EPA GPO
Demonstration Programs in Erosion EP 1.23/2:660/2-74-073
and Sediment Control: by B.C.Becker
et al., Hittman Associates, Columbia,
MD
93. EPA-670/2-73-059 *The Dual-Functioning Swirl Combined GPO
Sewer Overflow Regulator/Concentrator:EP 1.23/2:670/2-73-059
by R.Field, USEPA, Edison, NJNTIS
PB 227 182/3
94. EPA-670/2-73-067 *Hypochlorination of Polluted Storm- GPO
water Pumpage at New Orleans: by U.R. EP 1.23/2:670/2-73-067
Pontius, E.H.Pavis, Byrne Engi- NTIS
neering Corp., New Orleans, LA PB 228 581
95. EPA-670/2-73-071 Utilization of Trickling Filters for GPO
Dual-Treatment of Dry and Wet-HeatRir EP 1.23/2:670/2-73-071
Flows: by P.Homack. et al., E.T.NTIS
'RTTTam Assoc., Inc., Mi 11 burn, NJ PB 231 251
96. EPA-670/2-73-077 Combined Sewer Overflow Seminar GPO
Papers: by Storm and Combined Sewer EP 1.23/2:670/2-73-077
Technology Branch, USEPA, Edison, NJ NTIS
PB 231 836
97. EPA-670/9-74-004 *Excerpts from "Control of Infiltra- NTIS Pending
tion and Inflow into Sewer Systems,"
and "Prevention and Correction of Ex-
cessive Infiltration and Inflow into
Sewer Systems Manual of Practice,
January"1971."Complete reports can
be purchased from NTIS, See PB numbers
listed on third page of this Bibliography.
98. EPA-670/2-74-022 Computer Management of a Combined GPO
Sewer System: by C.P.Leiser. Muni- EP 1.23/2:670/2-74-022
cipality of Metropolitan Seattle, NTIS
Seattle, WA PB 235 717
•"Copies may be obtained from EPA Storm & Combined Sewer Section,
Edison, NJ 08817
442
-------
Ref.
No. Report Number Title/Author Source
99. EPA-670/2-74-026 *The Swirl Concentrator as a Grit NTIS
Separator Device: by R.H.Sullivan, PB 233 964
et al., American Public Works Assoc.,
Chicago, IL
TOO. EPA-670/2-74-033 *Manual for Deicing Chemical Storage NTIS
and Handling: by D.L.Richardson, et PB 236 152
al., Arthur D. Little, Inc.,
Cambridge, MD
101. EPA-670/2-74-039 *Relationship between Diameter and NTIS
Height for Design of a Swirl Concen- PB 234 646
trator as a Combined Sewer Overflow
Regulator: by R.H.Sullivan, et al.,
American Public Works Assoc.,
Chicago, IL
102. EPA-670/2-74-040 *Urban Stormwater Management and NTIS
Technology An Assessment:PB 240 687
by J.A.Lager and W.G.Smith, Metcalf
& Eddy, Inc., Palo'Alto, CA
103. EPA-660/2-74-043 Prediction of Subsoil Erodibility GPO
Using Chemical. Mineralogical and' EP 1.23/2:660/2-74-043
Physical Parameters: by C.B.Roth. NTIS
D.W.Nelson, M.J.M.Romkens, PB 231 846
Cincinnati, OH
104. EPA-670/2-74-045 *Manual for Deicinq Chemicals: Appli- NTIS
cati on Practi ces: D.L.R1chardson,PB 239 694
Arthur D. Little, Inc., Cambridge, MD
105. EPA-670/2-74-049 *Microstraining and Disinfection of GPO
Combined Sewer Overflows-Phase IlTT EP 1.23/2:670/2-74-049
by M.B.Maher, Crane Co., King ofNTIS
Prussia, PA PB 235 771
106. EPA-670/2-74-050 Combined Sewer Overflow Treatment NTIS ONLY
by the Rotating Biological Contactor PB 231 892
Process: by F.L.Welsh, D.J.Stucky,
Autotrol Corp., Milwaukee, WI
107. EPA-670/2-74-075 *Surge Facility for Wet- and Dry- GPO
Weather Flow Control: by H.L.Wei born EP 1.23/2:670/2-74-075
City of Rohnert Park, CA NTIS
PB 238 905
108. EPA-670/2-74-079 An Evaluation of Three Combined NTIS ONLY
Sewer Overflow Treatment AlteTna- PB 239 115
tives: by J.W.Parks, et al.,
£Tty~bf Shelbyville, IL
109. EPA-670/2-74-086 Chemical Impact of Snow Dumping NTIS ONLY
Practices: by J.P.O'Brien, et al., PB 238 764
Arthur D. Little, Inc., Cambridge, MD
*Copies may be obtained from EPA Storm and Combined Sewer Section,
Edison, NO 08817
443
-------
Ref.
No. Report Number Title/Author Source
110. EPA-670/2-74-087 Assessment and Development Plans for NTIS ONLY
Monitoring of prganics in StormPB 238 810
Flows: by A.Molvar, A. Tul niello,
Raytheon Co., Portsmouth, RI
111 EPA-670/2-74-090 *Countermeasures for Pollution from NTIS
Overflows: by R.Field, USEPA. and PB 240 498
J.A.Lager, Metcalf & Eddy, Inc.,
Palo Alto, CA
112. EPA-670/2-74-096 Characterization and Treatment of NTIS
Urban Land Runoff; by Newton V. PB 240 978
Colston, Jr., North Carolina State
University, Raleigh, NC
113. EPA-670/2-75-002 *Suspended Solids Monitor: by John W. NTIS
Liskowitz, et al., American Standard PB 241 581
Inc., New Brunswick, NJ
114. EPA-670/2-75-010 *Multi-Purpose Combined Sewer Overflow NTIS
Treatment Facility, Mt. Clemens, MI: PB 242 914
by V.U.Mahida, F.J.DeDecker, Spalding
DeDecker & Assoc., Madison Heights, MI
115. EPA-670/2-75-011 *Physical and Settling Characteristics NTIS
of Particulars in Storm and Sanitary PB 242 001
Wastewater; by R.J.Dalrymple. et al,
Beak Consultants for American Public
Works Assoc., Chicago, IL
116. EPA-670/2-75-017 *Stormwater Management Model User's NO NTIS
Manual-Version II: W.C.Huber, et al.,
University of Florida, Gainesville, FL
117. EPA-670/2-75-019 *Biological Treatment of Combined NTIS
Sewer Overflow at Kenosha, WI: by PB 242 126
R.W.Agnew.et al., Envirex, Mil-
waukee, WI
118. EPA-670/2-75-020 *Sewage System Monitoring and Remote NTIS
Control: by T.R.Watt. et al.. Detroit PB 242 107
Metro Water Department, Detroit MI
119. EPA-670/2-75-021 *Bench-Scale High-Rate Disinfection NTIS
of Combined Sewer Overflows: by P.E. PB 242 296
Moffa, et al., O'Brien & Gere Engrs.,
Syracuse, NY
120. EPA-670/2-75-022 *Urban Stormwater Management Modeling NTIS
and Decision-Making: by J.P.Heaney PB 242 290
and W.C.Huber, University of Florida,
Gainesville, FL
*Copies may be obtained from EPA Storm and Combined Sewer Section,
Edison, NJ 08817
444
-------
Ref.
No. Report Number Title/Author Source
121. EPA-670/2-75-035 Stream Pollution Abatement by Supple- NTIS ONLY
mental Pumping: by C.W.Reh and W.E.PB 239 566
Saddler, City of Richmond, VA
122. EPA-670/2-75-041 *Storm Water Management Model: Pis- NTIS
semination and User Assistance:PB 2242 544
J.A.Hagerman and F.R.S.Dressier,
University City Science Center (UCSC),
Philadelphia, PA
123. EPA-670/2-75-046 *Rainfall-Runoff Relations on Urban NTIS
and Rural Areas: by E.F.Brater and PB 242 830
J.D.Sherrill, University of Michigan,
Ann Arbor, MI
124. EPA-670/2-75-054 Characterization and Treatment of NTIS ONLY
Combined Sewer Overflows: by Engi- PB 241 299
neering Science Inc. for City and
County of San Francisco, CA
125. EPA-670/2-75-065 *Short Course Proceedings, Application NTIS
of Stormwater Management Models:PB 247 163
F.DiGiano, et al./University of
Massachusetts, Amherst, MA
126. EPA-670/2-75-067 *Automatic Organic Monitoring System NTIS
for Storm ana Combined Sewers: byPB 244 142
A.Tulumello, Raytheon Co., Ports-
mouth, RI
127. EPA-440/9-75-004 *Water Quality Management Planning for NTIS
Urban Runoff: by G.Amy, et al.,PB 241 689
Woodward-Clyde, San Francisco, CA
128. EPA-600/2-75-004 *Contributioris of Urban Roadway Usage NTIS
to Mater_Pollution: by D.G.Shaheen, PB 245 854
Biospherics Inc., Rockville, MD
129. EPA-600/2-75-007 Impact of Hydro!ogic Modifications on NTIS
Water Quality: by J.Bhutani, et al.. PB 248 523
Mitre Inc., McLean, VA
130. EPA-600/2-75-027 *Sewer Flow Measurement-A State-of- NTIS
the-Art Assessment: by P.E.Shelley PB 250 371
and G.A.Kirkpatrick, EG&G Washington
Analytical Services Center, Inc.,
Rockville, MD
131. EPA-600/2-75-033 *A Treatment of Combined Sewer Over- NTIS
flows by Dissolved Air Flotations: PB 248 186
by T.A.Bursztynsky, et al., Engineer-
ing Science Inc., Berkeley, CA
*Copies may be obtained from EPA Storm and Combined Sewer Section,
Edison, NJ 08817
445
-------
Ref.
No. Report Number Title/Author source
132. EPA-600/2-75-Q62 *The Helical Bend Combined Sewer Over- NTIS
flow Regulator: by R.H.Sullivan, et PB 250 619
al., American Public Works Assoc.,
Chicago, IL
133. EPA-600/2-75-065 *An Assessment of Automatic Sewer NTIS
Flow Samplers-!975: by P.E.ShelTey. PB 250 987
EG&G Washington Analytical Services
Center, Inc., Rockville, MD
134. EPA-600/2-75-071 *Detention Tank for Combined Sewer NTIS
Overflow: by Consoer, Townsend and PB 250 427
Associates, Milwaukee, WI
135. EPA-600/2-76-006 *Design and Testing of a Prototype NTIS
Automatic Sewer Sampling System: PB 252 613
by P.Shelley, EG&G Washington Analyt-
ical Service Center Inc., Rockville, MD
136. EPA-600/2-76-058 Future Direction of Urban Water NTIS ONLY
Models: by M.Sonnen, Water Resources PB 249 049
Engineers (WRE), Walnut Creek, CA
137. EPA-600/2-76-095 *Urban Runoff Pollution Control NTIS
Program Overview: FY 76: R.Field, PB 252 223
A.N.Tafuri, H.E.Masters, USEPA, In-house
Edison, NJ Report
138. EPA-600/2-76-105 *An Economic Analysis of the Environ- NTIS
mental Impact of Highway Deicing: by PB 253 268
D.M.Murray and U..F.W.Ernst, Abt
Associates, Inc., Cambridge, MA
139. EPA-600/2-76-115 *A Passive Flow Measurement System NTIS
for Storm and Combined Sewer:PB 253 383
by K.Foreman, Grumman Ecosystems Corp.,
Bethpage, NY
140. EPA-600/2-76-116 *Urban Stormwater Runoff Determination NTIS
of Volumes and Flowrates: by B.C.Yen" PB 253 410
and V.T.Chow, University of Illinois,
Urbana, IL
140a. WPD 03-76-04 *Proceedings Urban Stormwater Manage- NTIS
ment Seminars: Atlanta, GA. Nov. 4-6. PB 260 889
and Denver, CO, Dec. 2-4, 1975,
Edited by Dennis Athayde, USEPA,
Water Planning Div., Washington, DC
141. EPA-600/2-76-175a*Assessment of Mathematical Models for PTIS
Storm and Combined Sewer Management: ^B 259 597
by A.Brandstetter, Battene, Pacific
Northwest Lab., Rich!and, WA
*Copies may be obtained from EPA Storm and Combined Sewer Section,
Edison, NJ 08817
446
-------
Ref.
No. Report Number
Title/Author
Source
142. EPA-600/2-76-175b Assessment of Mathematical Models for MTIS ONLY
Storm and Combined Sewer Management- PB 258 644
Appendix: by A.Brandstetter, Battelle,
Pacific Northwest Lab., Rich! and, WA
143. EPA-600/2-76-217a Urban Runoff Characteristics-Vol . I, NTIS ONLY
Analytical Studies: by H.C.Preul and PB 258 033
C.N.Papadakis, University of Cincin-
nati, Cincinnati, OH
144. EPA-600/2-76-217b Urban Runoff Characteristics-Vol. II, NTIS ONLY
by H.C.Preul and C.N.Papadakis, PB 258 034
University of Cincinnati, Cincinnati,
OH
145. EPA-600/2-76-145 *Methodo1ogy for the Study of Urban NTIS
Storm Generated Pollution and Control :PB 258 743
by Envirex, Environmental Sciences
Division, Milwaukee, WI
146. EPA-600/2-76-222a*Wastewater Management Program,
Jamaica Bay-Vol.I, Summary Report:
by. D.L.Feurstein .and W.O.Maddaus,
City of New York, NY
147. EPA-600/2-76-222b Wastewater Management Program,
Jamaica Bay-VoK II, Supplemental
Data, NYC Spring Creek: by D.L.
Feurerstein and W.O.Maddaus, City
of New York, NY
148. EPA-600/2-76-218 *Deve]opment and Application of a
Simplified Stormwater Management
Model: by Metcalf & Eddy. Inc. Palo
CA
149. EPA-600/2-76-244 *Proceedings of Workshop on Micro-
organism in Urban Stormwater:
March 24, 1975, Storm and Comb i n ed
Sewer Section, USEPA, Edison, NJ
150. EPA-600/2-76-243 *Wastewater Flow Measurement in
Sewers Using Ultrasound, Milwaukee:
by R.J.Anderson and S.S.Bell, City
of Milwaukee, WI
151. EPA-600/2-76-271 *The Swirl Concentrator for Erosion
Runoff Treatment: by R.H. Sullivan,
et al . , American Public Works Assoc.,
Chicago, IL
152. EPA-600/2-76-242 *Development of a Hydrophobic Sub-
stance to Mitigate Pavement Ice Ad-
fiesion: by B.H.Alborn and H.C.Poehl-
mann, Ball Bros., Inc., Boulder, CO
NTIS
PB 260 887
NTIS ONLY
PB 258 308
NTIS
PB 258 074
NTIS
Pending
NTIS
Pending
NTIS
Pending
NTIS
Pending
*Copies may be obtained from EPA Storm and Combined Sewer Section,
Edison, NJ 08817
447
-------
Ref.
No.
Report Number Title/Author
Source
153. EPA-600/2-76-275 *Storm Water Management Model Level I
Preliminary Screening Procedures:
by J.P.Heaney, et al., University of
Florida, Gainesville, FL
154. EPA-600/2-76-272 *Demonstration of Void Space Storage
with Treatment and Flow Regulation:
by Karl R. Rohrer Assocs., Inc.,
Akron, OH
155. EPA-600/2-76-228
Demonstration of Interim Techniques
for Reclamation of Polluted Beach-
water: by J.F.Weber, City of Cleve-
TancTT OH
NTIS
PB 259 916
NTIS
Pending
NTIS ONLY
PB 258 192
156.
157.
158.
159.
160.
161.
EPA-600/2-76-286 *Cost Estimating Manual—Combined NTIS
Sewer Overflow Storage Treatment: Pending
by H.H.Benjes, Jr., Gulp, Wesner,
Gulp, Inc., El Dorado Hills, CA
Nationwide Evaluation of Combined At Printers
Sewer Overflows and Urban Stormwater
Discharges, Vol. II; Cost Assessment"
and Impacts: by J.F.Heaney, et a!.,
University of Florida, Gainesville, FL
Field Prototype Demonstration of the DRAFT
Swirl Degritter: by R.H.Sullivan, et
al., American Public Works Assoc.,
Chicago, IL
*Handling and Disposal of Sludges from At Printers
Combined Sewer Overflow Treatment-
Phase I (Characterization): by M.K.
Gupta, et al., Envirex, Environmental
Science Division, Milwaukee, WI
Microorganisms in Urban Stormwater:by DRAFT
V.P.Olivieri, et al., The Johns
Hopkins University, Baltimore, MD
Assessment of the Impact of the DRAFT
Handling and Disposal of Sludges
An'sing from Combined Sewer Overflow
Treatment: by M.J.Clark and A.Geino-
polos, Envirex, Environmental Sciences
Division, Milwaukee, WI
162- Swirl Device for Regulating and At Printers
Treating Combined Sewer Overflows.
EPA Technology Transfer Capsule
Report: by R.Field and H.E.Masters.
USEPA, Storm and Combined Sewer Sec.,
Edison, NJ
^Copies may be obtained from EPA Storm and Combined Sewer Section,
Edison, NJ 08817
448
-------
Ref.
No. Report Number Title/Author Source
163. EPA-600/2-77-033 Methods for Separation of Sediment NTIS ONLY
from Storm Hater at ConstructionPending
Sites: by J.F.Ripken, et al., Univ.
of Minnesota, Minneapolis, MM
164. Nationwide Evaluation of Combined DRAFT
Sewer Overflows and Urban Stormwater
Discharges. Vol. Ill: Characterization:
by R.H.Sullivan, et al., American
Public Works Assoc., Chicago, IL
165. Cost-Effective Pollution Control of DRAFT
Combined Wastes and Urban Runoff: by
Clinton Bogert Assocs., Fort Lee, NO
166. Analysis of Practices for Preparing DRAFT
an Economic Analysis and Determining
Infiltration and Inflow: Vol. II:
Manual of Practice, Sewer System
Evaluation Rehabilitation and New
Construction: by R.H.Sullivan, et
al., American Public Works Assoc.,
Chicago, IL
167. EPA-440/9-75-001 Report on State Sediment Control NTIS
Institutes Program: USEPA, Office of PB 241 088
Water Planning and Standards
168. EPA-600/8-76-001a Erosion and Sediment Control Audio- NTIS
Visual Training Program: Instruction PB 256 901
Manual: by The State of Maryland
Water Resources Administration; Dept.
of Transportation, The Federal High-
way Administration; The U.S. Department
of Agriculture, Soil Conservation
Service; and USEPA, Office of Research
and Development
169. EPA-600/8-76-001b Erosion and Sediment Control Audio- NTIS
visual Training Program: Workbook: PB 258 471
by The State of Maryland Water Resources
Administration; Department of Transpor-
tation, The Federal Highway Adminis-
tration; The U.S. Department of Agri-
culture, Soil Conservation Service;
and USEPA, Office of Research and
Development
170. EPA-600/2-77-015 *Treatment of Combined Sewer Overflows NTIS
by High Gradient Magnetic Separa-Pending
tion: by John Oberteuffer, et al.,
Sal a Magnetics, Cambridge, MA
*Copies may be obtained from EPA Storm and Combined Sewer Section,
Edison, NJ 08817
449
-------
Ref.
No. Report Number
Title/Author
Source
171.
172.
173.
174.
Cottage Farm Combined Sewer Detention NTIS ONLY
and Chi on'nation Station, Cambridge, Pending
MA: by Commonwealth of MA Metropolitan
District Commission, Boston, MA
Bachman Treatment Facility for Ex-
cessive Storm Flow in Sanitary
Sewers: by H.W.Wolf, Texas A&M
University, for Dallas Water
Utilities, Dallas, TX
NTIS ONLY
Pending
Evaluation of Fluidic Combined Sewer At Printers
Regulators Under Municipal Service
Conditions: by P.A.Freeman, Peter A.
Freeman Assoc., Inc., Berlin, MD
Catchbasin Technology Overview and
Assessment: by J.J.Lager, et al..
Metcalf & Eddy, Inc., Palo Alto, CA,
in association with Hydro-Research-
Science, Santa Clara, CA
At Printers
450
-------
ONGOING URBAN RUNOFF POLLUTION CONTROL PROJECTS
Project
Reference
Number
On-Going Projects
P-l
P-2
P-3
P-4
P-5
P-6
P-7
P-8
P-9
P-10
p-n
P-12
"Nationwide Characterization, Impacts, and Critical Evaluation
of Combined Sewer Overflow, Stormwater, and Non-Sewered Urban
Runoff." American Public Works Association, 68-03-0283
"Disinfection/Treatment of Combined Sewer Overflows -
Syracuse, N.Y." Onondaga County, N.Y., 802400
"Development of a Swirl Concentrator and a Helical Combined
Sewer Overflow Dual Functioning Regulator-Separator."
American Public Works Association, 68-03-0272
"Demonstration of a Swirl Regulator/Solids Separator System
for Control of Combined Sewer Overflows." City of Lancaster,
Pennsylvania, 802219
"State-of-the-Art Update on Storm and Combined Sewer Overflow
Management and Treatment, and An Urban Planning Guide for the
Assessment of Storm Flow Pollution and the Selection of System
Pollution Control Methods." Metcalf & Eddy, Inc., 68-03-2228
"Use of Polymers to Reduce or Eliminate Sewer Overflows in the
Bachman Creek Sewer." City of Dallas, Texas, 11022 DZU
"Combined Sewer Fluidic Regulator Demonstration." City of
Philadelphia, 11022 FWR
"Development of a Flocculation-Flotation Module." Hercules,
Inc., 14-12-855
"Stormwater Treatment Facilities." City of Dallas, Texas,
11023 FAW
"The Lawrence Avenue Underflow Sewer System." City of Chicago
11022 EMD
"Microorganisms in Stormwater." John Hopkins University,
802709
"Nutrient Removal Using Existing Combined Sewer Overflow
Treatment Facilities." Onondaga County, N.Y., 802400
Note: Number appearing in left margin corresponds to reference numbers
cited in report text.
451
-------
Project
Reference
Number
On-Going Projects
P-13
P-14
P-15
P-16
P-17
P-18
P-19
P-20
P-21
P-22
P-23
P-24
P-25
P-28
P-29
P-30
"Comparison of Alternate Sewer Design." City of Elizabeth
New Jersey, 802971
a) "Refine/Verify a Simplified Model to Handle Large Areas
with Minimal Data Input as a Planning Aid." Rochester Pure
Water Agency, Y-005141
b) "Combined Sewer Overflow Abatement Program - Rochester,
N.Y." Rochester Pure Water Agency, Y-005141
"Maximum Utilization of Water Resources in a Planned
Community." Rice University, 802433
"Evaluation of Present Catch Basin Technology and Demonstration
and Evaluation of New Upstream Attenuator/Solids Separator
Design." Metcalf & Eddy, Inc., 68-03-0274
"Analysis of Practices for Preparing an Economic Analysis and
Determining Infiltration." American Public Works Association,
803151
"Engineering Aspects of Storm and Combined Sewer Overflow
Technology A Manual of Instruction." North Carolina State
University, 801358
"Develop a Movie on Nature/Impacts of Stormwater Pollution
As Compared to Other Forms of Water Pollution." (SRO ID
No. 61ABR), EPA, Technology Transfer
"Characterization and Disposal of Combined Sewer Overflow
Sludges and Solids." Envirex, 69-03-0242
"Development and Demonstration of Combined Sewage Treatment
Utilizing Screening and Spilt-Air Flotation-" City of
Milwaukee (Hawley Road) 11020 FDC
"Demonstration of Screening/Dissolved-Air Flotation as an
Alternative to Combined Sewer Separation." City of Racine,
Wisconsin, 11023 FWS
"Sludge Treatment and Disposal Methods for Combined Sewer
Overflow." Envirex, 68-03-0242
"Demonstration Real-Time Automatic Control in Combined Sewer
System." City and County of San Francisco, California, 803743
"Evaluation of Stormwater Treatment Methods." Minnehaha
Creek Watershed District, 802535
"Evaluation and Technology Transfer of the Swirl Concentrator
Principle." American Public Works Association, 803157
"Demonstration/Evaluation of Impregnated Concrete Pipe and
Other Methods of Infiltration Control." Texas Water Quality
Board, 802651
452
-------
Project
Reference
Number
On-Going_Projects
P-31
P-32
P-34
P-37
P-39
P-40
P-41
P-42
P-45
P-46
P-49
P-50
P-51
P-53
P-68
P-70
P-71
"Trenchless Sewer Construction and Sewer Design Innovation."
Sussex County Council, Delaware, 800690
"The Somerville Marginal Conduit Including Pretreatment
Facilities." Boston Metropolitan District Commission, 11023 DME
"Large Scale Demonstration of Treatment of Storm-Caused Over-
flows by the Screening Method." City of Fort Wayne, Indiana,
11020 GYU
"Boston University Bridge Storm Water Detention and
Chlorination Station." Boston Metropolitan District
Commission, 11023 FAT
"Ultra-High Rate Filtration of Combined Sewer Overflow and Raw
Dry Weather Sewage at Newtown Creek Sewage Treatment Plant."
City of New York, 803271
"East Chicago Treatment Lagoon." East Chicago Sanitary
District, 11020 FAV
"Evaluation of Various Aspects of an Aluminum Storm Sewer
System." City of LaSalle, Illinois, 11032 DTI
"Pilot Plant Studies to Determine the Feasibility of Using
High Gradient Magnetic Separation (HGMS) for Treating Combined
Sewer Overflows." Sala Magnetics, Inc., 68-03-2218
"Development of Electromagnetic Flowmeter for Combined Sewer."
Cushing Engineering, Inc., 68-03-0341
"Efficiency of Off-Stream Detention-Retention Measures as
Sediment Control Devices." Howard University, 803066
"Collect and Define Availability of Test Data (Rainfall/Runoff)
For Urban Models-Data Base." University of Florida, 68-03-0496
"Develop.and Demonstrate New and.. .Improved Model for Design
of Combined Sewers to Prevent Solids Sedimentation and to
Optimize Construction Cost." Water Resources Engineers, Inc.,
68-03-2205
"Short Course on Application of Stormwater Management Models-
1975." University of Massachusetts, 803069
"A Guide for Comprehensive Planning for Control of Urban Storm
and Combined Sewer Runoff." University of Florida, 802411
"Verification of Water Quality Impact from CSO using Real-Time
Data." County of Milwaukee, 804518
"Optimization and Testing of Highway Materials to Mitigate Ice
Adhesion." Washington State University, 804660
"Evaluation and Technology Transfer of the Swirl Concentrator
Principal." American Public Works Association, 803157
453
-------
Project
Reference
Number
On-Going Projects
P-66
P-67
P-72
P-73
P-74
"Characterization of Solids Behavior in, and Variability
Testing of Selected Control Techniques for Combined Sewer
Systems." Northeastern University, 804578
"Demonstration of Non-Point Pollution Abatement through
Improved Street Cleaning Practices." San Jose, California,
804432
"Demonstration of Erosion and Sediment Control Technology."
State of California, 803181
"Methods of Separation of Sediment From Storm Water at
Construction Sites." University of Minnesota, 803579
"Demonstration and Evaluation of Sediment and Erosion Control
Techniques Applicable to the S.E. Piedmont, Fairfield County,
South Carolina." University of South Carolina, 803724
454
-------
OTHER URBAN RUNOFF POLLUTION CONTROL PROGRAM REFERENCES
Ref.
No. References
R-l Total Urban Pollutant Load: Sources and Abatement Strategies: Enviro
Control, Inc., for Council of Environmental Quality, Draft Report,
October 1973.
R-2 Sources of Metals in New York City Wastewater: Larry A. Klein, et al
JWPCF, Vol. 46, No. 12, December 1974.
R-3 Water Quality Effects From Urban Runoff: Robert E. Pitt and Richard
Field, Preprint, 1974 American Water Works Association Conference,
Boston, Massachusetts.
R-4 1974 Survey of Needs for Municipal Wastewater Treatment Facilities:
USEPA, Office of Water and Hazardous Materials, Washington, D.C.
R-5 Report to National Conmission on Water Quality on Assessment of Tech-
nologies and Costs for Publicly owned Treatment Works under Public"
Law 92-500, Volume TlMetcaTf& Eddy, Inc., September 1975.
R-6 Study and Assessment of the Capabilities and Cost of Technology for
Control of Pollutant Discharges from Urban Runoff:Black, Crow &
Eidness, Inc. and Jordan, Jones & Goulding, Inc., for the National
Conmission on Water Quality, Draft Report, July 1975.
R-6a Management and Control of Combined Sewer Overflows: Richard Field and
E.J. Struzeski, Journal Water Poll. Control Fed., Vol. 44, No. 6,
July 1972, pp 1393-1415.
R-6b Combined Sewer Overflows: Richard Field, Civil Engineering - ASCE
Magazine, February 1973, pp 57-60.
R-6c Coping with Urban Runoff in The United States: Richard Field, Water
Research, Vol. 9, Pergamon Press 1975, pp 499-505.
R-6d Urban Runoff Pollution Control - State of The Art: Richard Field and
John A. Lager, Journal of the Environmental Engineering Division, ASCE,
Vol. 101, No. EE1, Proc. Paper 11129, February 1975, pp 107-125.
R-6e Urban Runoff Must Be Controlled: Richard Field, Baltimore Engineer
Magazine, March 1975.
R-6f Literature Review - Urban Runoff and Combined Sewer Overflow: Richard
Field and Pauline Weigel, Journal Water Pollution Control Federation,
Vol. 45, No. 6, June 1973, pp 1108-1115.
Note: Number appearing in left margin corresponds to reference numbers
cited in report text.
455
-------
OTHER URBAN RUNOFF POLLUTION CONTROL PROGRAM"REFERENCES (continued)
Ref.
References
R-6g Literature Review - Urban Runoff and Combined Sewer Overflow: Richard
Field and Pamela Szeeley, Journal Water Pollution Control Federation,
Vol. 46, No. 6, June 1974, pp 1209-1226.
R_6h Literature Review - Urban Runoff and Combined Sewer Overflow; Richard
Field and Donna Knowles, Journal Water Pollution Control Federation,
Vol. 47, No. 6, June 1975, pp 1353-1369.
R-6i Literature Review - Urban Runoff and Combined Sewer Overflow: Richard
Field, J. Curtis, and R. Bowden, Journal Water Pollution Control
Federation, Vol. 48, No. 6, June 1976, pp 1191-1206.
R-7 Stormwater Pollution Control: A New Technology: Richard Field and
Anthony N. Tafuri, 28 Minute - 16 mm - Sound - Color Film, Available
from: General Services Administration, National Archives and Records
Service, National Audiovisual Center, Washington, D.C. 20409,
Rental - $12.50, Purchase - $119.50.
R-8 Areawide Assessment Procedures Manual: Hydroscience, Inc., USEPA,
Chapters 2 & 3, and Appendix I, Cincinnati, OH, September 1976.
R-9 Generalized Computer Program, Urban Storm Water Runoff, STORM:
Hydrologic Engineering Center for U.S. Army, Corps of Engineers,
723-S8-L2520, October 1974.
R-10 A Model for Evaluating Runoff-Quality in Metropolitan Master Planning:
L.A. Roesner. gt al, Water Resources Engineers, A.D. Feldman, The
Hydrologic Engineering Center, for U.S. Army, Corps of Engineers, A.O.
Fried!and, Department of Public Works, City of San Francisco, Tech-
nical Memorandum No. 23, ASCE, April 1974.
R-ll Water Pollution and Associated Effects From Street Salting: Richard
Field, Edmond J. Struzeski, Jr., Hugh Masters, Anthony Tafuri,
Journal of the Environmental Engineering Division, ASCE, Vol. 100,
No. EE2, Proc. Paper 10473, April 1974, pp 459-477.
R-12 Community Action Guideline for Soil Erosion and Sediment Control:
National Association of Counties Research Foundation, March 1970.
R-13 Standards and Specifications for Soil Erosion and Sediment Control in
Developing Areas:The United States Department of Agriculture, Soil
Conservation Service for The State of Maryland, June 1975.
R-14 Infiltration - Inflow Analysis: David J. Cesareo and Richard Field,
Journal of The Environmental Engineering Division, ASCE, Vol. 101,
No. EE5, Proc. Paper 11645, October 1975, pp 775-785.
R-15 Design of a Combined Sewer Overflow Regulator/Concentrator: Richard
Field, Journal Water Pollution Control Federation, Vol. 46, No. 7,
July 1974, pp 1722-1741.
R-16 Give Stormwater Pollutants the Spin: Richard Field, et al_, The
American City & Country Magazine, April 1976, pp 77-78.
456
-------
PLANNED WASTEWATER REUSE
A LITTLE-USED RESOURCE
F. M. Middleton
Senior Science Advisor
Municipal Environmental Research Laboratory
Environmental Research Center
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
ABSTRACT
Water reuse is a common fact of life. Water shortages and the recent recognition
in the United States of the need to conserve water has focused attention upon the value of
more intentional reuse. Planners recognize the need for a hierachy of water use in the
community. All water need not be of the same quality. And the wastewater of a community
should be considered a resource.
Wastewater reuse is being specifically recognized by recent legislation. Public
Law 92-500, the "Federal Water Pollution Control Act Amendments of 1972", calls for re-
search and facilities construction to permit reuse. Public Law 93-523, the "Safe Drinking
Water Act", passed in December, 1974 allows for grants to investigate and demonstrate
health implications involved in reclamation, recycling and reuse of wastewater to prepare
a safe and acceptable drinking water. The American Water Works Association and the Water
Pollution Control Federation has issued a joint statement in support of appropriate reuse.
Municipalities on an annual basis use about 4 X 10 m (10 trillion gallons) of
water and wastewater return amounts to 3 X 10^°m^ (8 trillion gallons). Present wastewater
Q -3
usage for specific purposes such as irrigation and cooling amount to only 5 X 100m°
(13 billion gallons) or less than 2% of the available flow. Much of the waste flow
can be put to productive use.
A great deal of research in EPA is directed toward some facet of wastewater reuse.
A major effort is now needed to embark upon a long-term integrated program to permit waste-
water reuse for any purpose including to supply drinking water. Some states and major
municipalities are already working on a variety of reuse projects. Our combined programs
should lead us to a sound base of science and technology that will ensure safety and gain
the public confidence for full-scale water reuse. The technology for preparing water of
any quality is well advanced. Needed is better knowledge on the level of residues that
remain and their possible health effects. Social and economic factors will need addition-
al research.
INTRODUCTION years. Severe contamination of many surface
supplies has occurred. Increasing instances
Abundant supplies of clean surface of groundwater contamination are being found.
and underground waters in the United States Thus, our relatively fixed volume of water
have been taken for granted until recent may become less and less usable. Adequate
457
-------
pollution control measures must be taken
and conservation and reclamation of
resources must become the rule.
Water has always been used and reused
by man. The natural water cycle, evapor-
ation, and precipitation is one of reuse.
The return of wastewaters to the streams
and lakes of the country is a fact of life.
The unplanned reuse of wastewaters is not
new. The planned reuse of wastewaters for
beneficial purposes has been done in some
areas for many years, but it is here that
we need to concentrate our efforts for far
greater use of our wastewaters.
The quality and quantity of waste-
waters produced by the community depend
upon such factors as the source of supply,
population density, industrial practices,
and even the attitudes of the local popu-
lation. The quality of the environment can
be improved by reducing pollution at the
source, providing adequate treatment of the
wastewaters, and by recycling and reusing
wastewater. Public support and some change
in social behavior will be required in most
instances.
DEFINITIONS
Since there are many different types
of wastewater reuse and the term "reuse"
has different meanings to different people,
the following definitions will be used for
this Workshop:
Municipal Wastewater - The spent water
of a community, consisting of water-carried
wastes from residences, commercial build-
ings, and industrial plants and surface or
groundwaters that enter the sewerage system.
Advanced Waste Treatment - Treatment
systems that go beyond the conventional
primary and secondary processes. Advanced
waste treatment systems may include bio-
logical processes, the use of chemicals,
activated carbon, filtration or separation
by membranes.
Indirect Reuse - Indirect reuse of
wastewater occurs when water already used
one or more times for domestic or industrial
purposes is discharged into fresh surface or
underground waters and is used again in its
diluted form.
Direct Reuse - The planned and deli-
berate use of treated wastewater for some
beneficial purpose such as irrigation, re-
creation, industry, prevention of salt
water intrusion by recharging of under-
ground aquifers, and potable reuse.
Potable reuse can be further divided
into two categories as follows:
Indirect Potable Reuse *- The planned
addition of treated wastewater to a drink-
ing water reservoir, underground aquifer,
or other body of water designed for potable
use that provides a significant dilution
factor.
Direct Potable Reuse - The planned
addition of treated wastewater to the head-
works of a potable water treatment plant or
directly into a potable water distribution
system.
OFFICIAL SUPPORT FOR WASTEWATER REUSE
The role of the U.S. Environmental Pro-
tection Agency (USEPA) and its predecessor
organizations in wastewater reuse has been
stated in various acts. Public Law 87-88
passed in 1961 amending the Federal Water
Pollution Control Act directed the Secre-
tary (at that time of Health, Education,
and Welfare) "to develop and demonstrate
practicable means of treating municipal
sewage and other water-borne wastes to
remove the maximum possible amount of
physical, chemical, and biological pollu-
tants in order to restore and maintain the
maximum amount of the Nation's water at a
quality suitable for repeated reuse."
This Act gave impetus to the Advanced
Waste Treatment Research Program, which
began in 1960. The objective of this
national program is to conduct research
that will develop new and improve existing
wastewater treatment processes and ultimate
disposal technology, thus permitting maxi-
mum removal of contaminants and repeated
reuse of the Nation's waters.
Public Law 92-500, the "Federal Water
Pollution Control Act Amendments of 1972",
recognizes the potentially large benefit to
be realized if wastewaters can be renovated
for reuse applications. Sections 201 (b),
201 (d), and 201 (g) (2) (B) clearly require
1. that EPA provide for the application of
best practicable waste treatment technology/
including reclaiming .and recycling of water;
458
-------
2. that construction of revenue producing
facilities providing for reclaiming and
recycling be encouraged; and 3. that works
proposed for grant assistance, to the extent
practicable, allow for the application of
technology at a later date which will provide
for reclaiming and recycling of water.
Section 105 (a) (2) authorizes EPA to make
grants for demonstrating advanced waste
treatment and water purification methods,
and Section 105 (d) (2) requires that the
Administrator conduct on a priority basis
an accelerated effort to develop, refine,
and achieve practical application of advanc-
ed waste treatment methods for reclaiming
and recycling water and confining pollutants.
The Safe Drinking Water Act of 1974
(Section 1444) also contains mandates of
importance with regard to renovation and
recycling of wastewaters. Section 1444
authorizes a development and demonstration
program to: demonstrate new or improved
technology for providing safe water supply
to the public; investigate and demonstrate
health implications involved in the recla-
mation, recycling and reuse of wastewaters
for the preparation of safe and acceptable
drinking water.
There exists, therefore, a strong and
clear legislative mandate for research
development and demonstration of reliable,
cost-effective technology for reclaiming
and recycling wastewaters for beneficial
uses. A major beneficial use is the
supplementation of domestic water supplies.
The Water Pollution Control Federa-
tion (WPCF) (1) and the American Water Works
Association (AWWA) issued a joint resolution
that urged the Federal Government to support
a massive research effort to develop needed
technology. These organizations underscored
the "lack of adequate scientific information
about possible acute and long-term effects
on man's health from such reuse", and also
noted that "the essential fail-safe tech-
nology to permit such direct reuse has not
yet been demonstrated." The resolution
recognizes the need for an "immediate and
sustained multi-disciplinary, national
effort to provide the scientific knowledge
and technology relative to the reuse of
water for drinking purposes in order to
assure full protection of the public health."
The USEPA in a policy statement on
water reuse dated July 7, 1972, supports
and encourages the development and practice
of successive wastewater reuse. EPA does
not currently support the direct inter-
connection of wastewater reclamation plants
with potable water systems.
SPECIFIC CONSIDERATIONS GOVERNING REUSE
The reuse of treated effluents is most
applicable where large volumes of water are
used and the wastes are not highly contami-
nated. The location of the treatment plant
and the possible transport of the renovated
water are important considerations. A
wastewater renovation plant need not always
be located at the same place as the munici-
pal wastewater disposal plant, nor should
the renovation process be dependent upon
treating the total flow. Treatment process-
es work most efficiently and economically
when dealing with a steady flow of waste-
water rather than with the irregular flow
normally experienced from urban sources.
This condition can be obtained by withdraw-
ing only a part of the urban wastewater;
this is depicted in Figure 1, which shows
how water renovation and reuse can be plan-
ned to best advantage in the community.
VOLUME OF WASTEWATERS
AVAILABLE IN MUNICIPALITIES
Municipalities on an annual basis use
about 4 X 10lOm3 (10 trillion gallons) of
water, and wastewater return amounts to
3 X 1010m3(8 trillion gallons). Present
wastewater usage for specific purposes is
shown in Table 1.
As can be seen from the Table, only
5 X 108m3 (136 billion gallons), or less
than 2% of the available flow, is used on a
planned basis. Much of the waste flow can
be put to productive use. Such uses can go
a long way in conserving scarce clean water
sources.
STANDARDS FOR WASTEWATER REUSE
To ensure the safety of water supplies,
standards have to be applied. Standards for
drinking water have been available for many
years. Although national standards may be
set for drinking water, the qualities of
river-water, industrial effluents, and re-
used wastewater are the responsibility of
the local controlling authority. Even so,
the standards set must take into account
459
-------
DISCHARGE OF
HOUSEHOLD SEWAGE
DISCHARGES
OF INDUSTRIAL
WASTES UNSUITABLE
FOR RECLAMATION
TRUNK
SEWER
EVEN FLOW
TO PLANT
WASTEWATER
RENOVATION PLANT
SLUDGES
RETURNED
TO SEWER
-*-CLEAN WATER FOR REUSE
TO MUNICIPAL
DISPOSAL PLANT
The diversion of wastewater from the trunk sewer to the wastewater renovation plant
should be chosen at a point where it is known that the trunk sewer contains only household
FIGURE 1. Simplified Wastawafer Reuse Scheme
*From World Health Organization Technical Report No. 517 (1973)
TABLE 1. WATER REUSE IN THE UNITED STATES**
Type
Irrigation and agriculture
Industrial
Recreational
Non-potable domestic
:Groundwater augmentation
Volume
m3
3 X 108
2 X 108
11 X 106
< 4 X 106
< 4 X 106
in 1971
billion gals
77
54
3
< 1
< 1
No. of Plants
338
14
5
1
8
*Estimated from information in EPA publication EPA-660/2-73-006b
"Wastewater Treatment and Reuse by Land Application" - Vols. I & II
**From World Health Organization Technical Report No. 517 (1973)
460
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the possible transport of pollutants across
state borders or the effects of discharges
on downstream water users. Standard setting
is a most difficult and critical job, with
important economic implications. Standards
must be given the force of law, and an
authority must be created to ensure that
they are observed.
Standards governing the quality of
water in rivers and lakes are becoming
common. Some countries have, and others
are formulating, standards applicable di-
rectly to effluents, though few countries
yet have standards for the planned reuse of
treated wastewater. As wastewater reuse
grows, it is important that standards be
set for specific reuse purposes.
As wastewater - treated or untreated -
has been reused in agriculture for a fairly
long time, some countries have developed
standards for this purpose. A summary of
some representative standards for the use
of renovated water in agriculture is given
in Table 2.
DOMESTIC REUSE
In any reuse application there are a
number of points to consider. One very
important question is whether the reuse
will result in multiple recycle. Multiple
recycle produces a buildup of refractory
materials, especially inorganic ions, and
may require the use of demineralization or
other specialized processes. In-plant reuse
of industrial water, where actual consump-
tion is small, may lead to a high degree of
recycle. On the other hand reuses of muni-
cipal wastewater, except for domestic reuse,
probably would not lead to multiple recycle.
Even in the case of domestic reuse there is
not likely to be total recycle. The reason
is that less water is ordinarily found arriv-
ing at the wastewater treatment plant than
is supplied to the municipal water system.
Such losses do occur and are quite large in
warm, dry areas where domestic reuse is
likely to be most widely practiced. In the
United States it is estimated (2) that these
losses range from less than 20% in humid
areas to about 60% in arid areas. Parkhurst
et al., (3) point out, based upon experience
in the Los Angeles area, that less than 50%
of a water supply would be available for
reuse. The disadvantage of these large
losses is the need for a substantial addi-
tional fresh water source. The advantage
is that the steady state mineral concentra-
tion is reduced. As a result, the degree of
demineralization may be reduced substantial-
ly below that needed if there were no loss-
es. Also, there is the flexibility of de-
mineralizing either the renovated wastewater
or the supplementary water source, there may
be advantages to demineralizing the supple-
mentary source.
Another consideration in reuse is the
character of the wastewater entering the
treatment plant, especially with respect
to industrial pollutants. Care must be
used to exclude materials that would be
detrimental to the reuse application. This
is especially true for domestic reuse, but
• also applies to less sophisticated reuse
applications. These materials may not be
those usually considered toxic. Ordinary
salt brines would be undesirable, for
example, if demineralization were being
carried out on the renovated wastewater.
In Los Angeles County, a survey of the
sewer systems has been made to determine
how much of the available wastewater has
potential for reuse. Waters having heavy
metal contamination or high total dissolved
solids were considered unacceptable. A
similar survey will be necessary for other
municipalities planning extensive reuse.
Another point that must be considered
is distribution of the renovated water. A
multiplicity of piping systems, each one
containing a different quality renovated
water, will not usually be practical. There
may be a number of large consumers in the
vicinity of the treatment .plant. This
would make distribution simple and inexpen-
sive. If the consumers are widely distri-
buted, however, one piping system in addi-
tion to the existing municipal water system
is almost certain to be the most that will
be economically realistic. The result is
that the renovated wastewater must be of a
quality to satisfy most of the customers
without additional treatment. Treatment
such as those necessary for boiler water
feed would be excluded, since present
practice in water supply has shown that
those treatments are more appropriately
carried out by the user.
INDIRECT REUSE
The following discussion of indirect
reuse taken in part from a World Health
Organization publication (4) is appropriate.
461
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Examples of indirect reuse in certain
rivers:
A study of a number of rivers in
the USA, carried out in 1961 (5) showed
that at periods of low flow 3.5-18.5%
of the water had passed through domestic
waste systems. If the volume of indus-
trial effluents is also taken into
account, it would be expected that 20-40%
of the river water at low flow in some
areas may be reused water.
Zoeteman in a World Health Organi-
zation publication (6) has plotted the
percent of river flow used for community
water supply versus the average yearly water
flow for 89 rivers, Figure 2. As might be
TABL6 2. EXISTING STANDARDS GOVERNING THE USE OF RENOVATED
WATER IN AGRICULTURE'
California
Israel
South Africa
Federal Republic
of Germany
Orchards and
/ineyards
Fodder,
-fibre crops,
and seed
crops
Crops for
human con-
sumption that
w/ll be pro-
cessed to Kill
pathogens
Crops for
human con-
sumption in
a raw state
Primary effluent;
no spray irrigation ;
no use of dropped
fruit
Primary effluent ;
surface or spray
irrigation.
For surface irriga-
tion, primary
effluent.
For spray irrigation,
disinfected sec-
ondary effluent (no
more than 23 coli-
form organisms per
100 mi).
For surface irriga-
tion, no more than
2.2 coliform organ-
isms per ICO ml.
For spray irrigation,
disinfected, filtered
waste water with
turbidity of 10 units
permitted, provid-
ing it has been
treated by coagula-
tion.
Secondary
effluent.
Secondary effluent,
but irrigation of
seed crops for
producing edible
vegetables pot
permitted.
Vegetables for hu-
man consumption
not to be irrigated
with renovated
wastewater unless
it has been properly
disinfected (< 1000
coliform organisms
per 100 ml in 80% of
samples).
Not to be irrigated
with renovated
wastewater unless
they consist of
fruits that are peel-
ed before eating.
Tertiary effluent, No spray irrigation
heavily chlorinated in the vicinity.
where possible. No
spray irrigation.
Tertiary effluent. Pretreatment with
screening and
settling tanks.
For spray irrigation,
biological treatment
and chlorination.
Tertiary effluent. Irrigation up to
4 weeks before
harvesting only.
Potatoes and
cereals— irrigation
through flowering
stage only.
*From World Health Organisation Technical Report No. 5l7 (1973)
462
-------
Fig. 2 RELATION BETWEEN AVERAGE YEARLY WATERFLOW AND
% RIVER WATERFLOW USED FOR COMMUNITY WATER
SUPPLY FOR 89 RIVERS IN THE WORLD IN 1968-1972
10000-
o
o
e
£t
V
1000.
10O'
1 0
01
TUGELA i s AFRICA i
001
01
• RHINE ( NETHERLANDS )
> DANUBE ( HUNGARY )
•COLORADO (USA)
I
• MURRAY (AUSTRALIA )
• THAMES
(UK)
e TECS
(UK)
-JAJRUO
( IRAN )
. •
10
100
V. RIVER WATERFLOW USED FOR COMMUNITY WATER SUPPLY
(Zoeteman. 1975)
463
-------
expected, the rivers with low flow show the
greatest percentage use. In the future, the
trend-line of Figure 2 will most likely move
upward to the higher river flow values. It
is important to know the amount of present
reuse and to forecast for future reuse. A
case in point is the Great Ouse River at
Clapham, Untied Kingdom where the present
and future content of effluent has been
tabulated, Table 3.
The Ruhr River in Germany has a re-
use factor of 36% half of the time and has
reached 86% under severe conditions. At
the 86% concentration of effluent it was
reported that 7% of the population of Essen,
Germany had non-bacterial gastroenteritis.
As treatment of wastewaters improves
future effluents will be less damaging to
water quality.
In the United Kingdom, the River
Thames, which provides two-thirds of the
water supply for the Greater London area,
contains about 14% of sewage effluent when
flowing at an average rate. During the
severe drought of 1975 the flow in the
Thames dropped from a daily volume of
35 m3/s (1,283 ft3/s) to 2.2 m3/s (77 ft3/s)
and the flow was, no doubt, nearly all efflu-
ent. In times of drought, the water supply
source for Agra, India consists almost en-
tirely of partially treated sewage from New
Delhi, 190 km away.
The Mardyke is a small river rising to
the east of London and discharging into the
Thames estuary. It has a dry-weather flow
of about 0.2 m3/s (7 ft3/s). The Essex
River Authority has devised a scheme where-
by about 0.4 m3 (14 ft3/s) per day of sand-
filtered secondary effluent from the River-
side wastewater treatment plant will be
pumped into the headwaters of the Mardyke
to supplement the flow, instead of being
discharged direct to the estuary as at
present. The mixture of river water and
effluent will be available for abstraction
under license by agricultural users in the
middle reaches and by industry at the lower
reaches-an area now suffering from a short-
age of water owing to saline intrusion into
the wells that provide much of the supply.
A further supply of sand-filtered effluent
will be made available for direct industrial
use.
The River Authorities in the United
Kingdom, according to Billington (7) have
formulated a guideline that suggests a
maximum limit of 75% sewage effluent in
rivers.
In the treatment of polluted rivers, the
methods employed at present are based upon
TABLE 3. ESTIMATED CONCENTRATION OF EFFLUENT IN GREAT OUSE RIVER
% Concentration of Effluent
40
60
75
80
464
-------
those developed over the years for the
treatment of relatively unpolluted river
water, and it appears that sufficient note
may not have been taken of the increasing
proportion of wastes in many rivers.
The inadequacy of these traditional
methods may perhaps be indicated by the out-
breaks of infectious hepatitis in New Delhi
in 1955-56 [Dennis (8); Viswanathan (9)],
when there were 30,000 cases, and in 1958.
The waterworks in question was of modern
design and, though there may have been some
faults in operation, they were of the sort
that may occur at any waterworks. However,
at the time of the outbreak drought condi-
tions prevailed, and the water abstracted
from the river was estimated to contain
about 50% of sullage water.
It appears, therefore, that the public
health aspects of the production of potable
water from polluted rivers should be review-
ed. When rivers contain a high proportion
of effluent, the production of water from
them should be regarded as analogous to the
direct recovery of water from a sewage or
industrial effluent, and safeguards appro-
priate to this situation should be imposed.
There is also an increasing need to
consider the optimum distribution of puri-
fication between the wastewater treatment
plant, the river itself (self-purification),
and the treatment plant that produces pot-
able water. There are two extreme cases:
(a) Wastewater is discharged with
little or no treatment, all the
purification occurring in the river
or at the water treatment plant.
This practice has been common in
the past but is rapidly disappear-
ing. In fact, raw sewage disposal
into rivers is prohibited in some
countries. Local authorities are
requiring secondary treatment and,
in some cases, the removal of the
nutrients, phosphorus and nitrogen,
because incidental pollution that
is as yet uncontrolled may well
use up the natural purifying
capacity of the river.
(b) The wastewater is purified to
a standard as high as that of the
river water into which it is dis-
charged, so that the type and degree
of purification required at the water
treatment plant is no different
from that which would be required
in the absence of the wastewater
discharge.
Almost certainly the optimum solution
lies somewhere between these two extremes,
and optimization studies are required to
determine it, taking into account all the
costs and benefits involved. This may be
difficult in practice because some of the
social costs and benefits cannot readily
be expressed in economic terms. Such
optimization studies are likely to be
most successful in the context of a single
river basin authority having control over
the treatment and discharge of wastewaters
and also over the abstraction and treatment
of potable waters.
The unintentional reuse of wastewater
also occurs widely as a result of the use
of river water for agriculture, recreation,
and industrial supply and for these pur-
poses, too, there is a need for appropriate
safeguards.
DIRECT REUSE
The only known case in the United
States where treated municipal effluent is
used for a domestic purpose is at the Grand
Canyon where the treated effluent is used
for toilet flushing and other n |