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EPA-600/9-76-023
October 1976
PROCEEDINGS
FOURTH UNITED STATES/JAPAN CONFERENCE ON
SEWAGE TREATMENT TECHNOLOGY
Cincinnati, Ohio: October 23-24, 1975
Washington, D.C.: October 28-29, 1975
Office of International Activities
Office of Water and Hazardous Materials
Washington, B.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 en-
dorsement or recommendation for use.
ii
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FOREWORD
The industry and technical ability of the Japanese and
American people have brought prosperity to our two nations
but have also created grave strains on the environment.
Both nations are conscious of the need to control pollution
and protect the environment.
US-Japan environmental cooperation has been going on
for several years. The fruits of our mutual labors are
becoming visible. The United States and Japan have now
completed the fourth in a series of Joint Conferences on
Sewage Treatment Technology. Both countries have profited
from this exchange. These Proceedings, representing the
most up-to-date information in several areas of wastewater
treatment, will be welcomed for their contribution to our
knowledge in this field/"
Russell E. Train
Administrator
Washington, B.C.
July, 1976
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CONTENTS
FOREWORD
JAPANESE DELEGATION vi
U. S. - CINCINNATI DELEGATION vii
U. S. - WASHINGTON DELEGATION viii
JOINT COMMUNIQUE
JAPANESE PAPERS
1 THROUGH 8
EPA - CINCINNATI PAPERS 503
EPA - WASHINGTON PAPERS 628
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JAPANESE DELEGATION
DR. TAKESHI KUBO
Head of Delegation, Executive Director, Japan Sewage
Works Agency
TOHRU HAYASHI
Head, Water Quality Control Division, Water Quality
Bureau, Environmental Agency
DR. MAMORU-KASHIWAYA
Head, Water Quality Control Division, Public Works
Research Institute, Ministry of Construction
KEN MURAKAMI
Chief, Water Quality Section, Water Quality Control
Division, Public Works Research Institute, Ministry of
Construction
DR. AKINORI SUGIKI
Head, Research and Technology Development Division,
Japan Sewage Works Agency
MASAYUKI SATO
Director, Sewage Works Bureau, Yokohama City Office
SEIICHI YASUDA
Director, Sewage Works Bureau, Kyoto City Office
SATORU TOHYAMA
Head of Sewage Works Division, Dept. of Sewerage
& Sewage Purification, Ministry of Construction
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UNITED STATES/CINCINNATI DELEGATION
FRANCIS M. MIDDLETON
General Chairman of the Conference and
Head of the Cincinnati U.S. Delegation;
(Acting) Senior Science Advisor, MERL
LOUIS W. LEFKE
(Acting) Director, MERL
EDWIN F. EARTH
Chief, Biological Treatment Section,
TPDB, WRD, MERL
RICHARD C. BRENNER
Sanitary Engineer, Biological Treatment
Process Branch, WRD, MERL
JOHN CIANCIA
Sub-Program Chief, Industrial Treatment
and Control, Industrial Environmental
Research Laboratory (Edison, New Jersey)
JESSE M. COHEN
Chief, Physical-Chemical Treatment
Section, TPDB, WRD, MERL
JOHN J. CONVERY
(Acting) Director, WRD, MERL
JOHN N. ENGLISH
Sanitary Engineer, Municipal Treatment
and Reuse Section, SEEB, WRD, MERL
DR. JOSEPH B. FARRELL
Chief, Ultimate Disposal Section, TPDB,
WRD, MERL
RICHARD I. FIELD
Chief, Storm and Combined Sewer Section,
SEEB, WRD, MERL (Edison, New Jersey)
ROBERT A. OLEXSEY
MechanicaJ Engineer, Ultimate Disposal
Section, TPDB, WRD, MERL
JOSEPH F. ROESLER
Sanitary Engineer, Pilot and Field Eval-
uation Section, Technology Development
and Support Branch, WRD, MERL
B. VINCENT SALOTTO
Research Chemist, Ultimate Disposal
Section, TPDB, WRD, MERL
DR. JAMES E. SMITH
Sanitary Engineer, Ultimate Disposal
Section, TPDB, WRD, MERL
JAMES J. WESTRICK
Sanitary Engineer, Physical-Chemical
Treatment Section, TPDB, WRD, MERL
MERL - Municipal Environmental Research Laboratory
WRD - Wastewater Research Division
TPDB - Treatment Process Development Branch
SEEB - Systems and Engineering Evaluation Branch
Vll
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UNITED STATES/WASHINGTON DELEGATION
FRANCIS M. MIDDLETON
General Chairman of the Conference;
(Acting) Senior Science Advisor, MERL
(Cincinnati, Ohio)
JOHN T. RHETT
Head of Washington U.S. Delegation;
Deputy Assistant Administrator for Water
Program Operations, OWHM
CHARLES H. SUTFIN
Deputy Head of Washington U.S. Delegation;
Deputy Director, Municipal Construction
Division, Water Program Operations, OWHM
ROBERT A. CANHAM
Executive Secretary, Water Pollution
Control Federation
FRANCIS J. CONDON
Sanitary Engineer, Community Sources
Staff, Waste Management Division, Air,
Land, and Water Use, ORD
FITZHUGH GREEN
Associate Administrator for International
Activities
ERNEST P. HALL
Deputy Director, Effluent Guidelines
Division, Water Planning and Standards,
OWHM
JOE G. MOORE, JR.
Program Director, "National Commission
on Water Quality
WALTER S. GROSZYK
Deputy Director, Water Planning Division,
Water Planning and Standards, OWHM
WILLIAM A. ROSENKRANZ
(Acting) Director, Waste Management
Division, Air, Land, and Water Use, ORD
ROBERT B. SCHAFFER
Director, Permits Division, Water
Enforcement, Office of Enforcement
DR. WILSON K. TALLEY
Assistant Administrator for Research
and Development
CALVIN C. TAYLOR
Economic Analyst, Interagency Liaison
Office, Region IV (Atlanta, Georgia)
ADDITIONAL PARTICIPANT
KIRK MACONAUGHEY
Japanese Coordinator, Office of
International Activities
OWHM - Office of Water and Hazardous Materials
ORD - Office of Research and Development
MERL - Municipal Environmental Research Laboratory
VI11
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DR. TAKESHI KUBO, JAPANESE TEAM LEADER
OPENS THE CONFERENCE AT EPA IN CINCINNATI, OHIO
»mo sum ot
NTAL MOUCTiQN AGE
OHMJKTM IIJUICU C«Tl*
:
JAPANESE TEAM VISITS THE NEW EPA
ENVIRONMENTAL RESEARCH CENTER, CINCINNATI, OHIO
ix
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JAPANESE VISIT ROCKY RIVER, OHIO
PHYSICAL-CHEMICAL TREATMENT PLANT
JAPANESE VISIT CONSTRUCTION SITE
OF PHYSICAL-CHEMICAL TREATMENT PLANT
NIAGARA FALLS, NEW YORK
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X
H-
JOE G, MOORE (FAR LEFT) ADDRESSES JOINT CONFERENCE - WASHINGTON, D,C,
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Joint Communique
Fourth U.S./Japan Conference on Sewage Treatment Technology
Washington, D. C.
October 29, 1975
1. The Fourth United States/Japan Conference on Sewage Treatment Technology
was held in Cincinnati, Ohio and Washington, D. C., from October 23-29, 1975.
2. The Japanese delegation, headed by Dr. Takeshi Kubo, Executive Director,
Japan Sewage Works Agency, was composed of six National Government officials and
two local Government officials.
3. Mr. Frank M. Middleton, Senior Science Advisor, U. S. Environmental
Protection Agency, Cincinnati, Ohio, was General Chairman of the Conference.
Mr. John T. Rhett, Deputy Assistant Administrator for Water Program Operations
was Head of the Washington delegation. Mr. Charles H. Sutfin, Deputy Director,
Municipal Construction Division, was Deputy Head of the Washington delegation.
In addition to EPA officials, Conference delegates included Joe G. Moore, Jr.,
Program Director, National Commission on Water Quality, and Robert A. Canham,
Executive Secretary, Water Pollution Control Federation.
4. Prior to the Conference the Japanese delegates visited advanced waste
treatment facilities in Orange County, California, and Escondido, California.
Physical chemical treatment plants were seen in Rocky River, Ohio, Cleveland,
Ohio, and Niagara Falls, New York. The pure oxygen treatment plant in Detroit,
Michigan was visited. In Washington, D. C., the EPA Blue Plains Sewage Treatment
Pilot Plant was visited and a tour of the Piscataway tertiary treatment plant
was made.
5. Principal topics of the Fourth Conference in Cincinnati were status of
pure oxygen use, sludge handling and disposal by heat treatment, incineration and
land disposal, urban storm water technology, automation and instrumentation, use
of activated carbon, filtration, phosphorus removal, industrial waste treatment
progress, reuse and disinfection. In Washington the U. S. side discussed aspects
of Public Law 92-500 including planning, urban runoff, permits, pretreatment, con-
struction grants status and the tentative conclusions of the National Commission
on Water Quality. The Japanese side discussed environmental improvement in
Japan, comprehensive planning, combined sewer overflow technology, pretreatment
and case histories of industrial waste treatment. Vigorous discussions followed
the conference presentations.
6. Recent personnel exchanges include a month-long visit to Japan by Dr.
James E. Smith and Mr. Dolloff F. Bishop of the EPA Taft Center, Cincinnati, Ohio.
Dr. K. Inaba, Japan Sewage Works Agency, is spending six months in the United
States to study storm sewer flows and urban runoff problems.
7. In the research area it was agreed to enter into joint projects in areas
of municipal sludge disposal technology, agricultural use of sludge, nitrogen
control technology, instrumentation and automation of wastewater treatment plants
and other interests to both countries. Researchers on both sides will exchange
information on a regular basis. Full reports will be given at future conferences.
8. It was proposed by the Japanese side that the Fifth U. S./Japan Conference
should be held in Japan, about May 1977-
9. A Proceedings of the Conference will be printed in English and Japanese.
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Fourth US/JAPAN Conference
on
Sewage Treatment Technology
Paper No. 1
SLUDGE TREATMENT AND DISPOSAL
October 24, 1975
Cincinnati, Ohio
Ministry of Construction
Japanese Government
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SLUDGE TREATMENT AND DISPOSAL
1. Sludge Handling Practice in Japan 4
A. Sugiki, Japan Sewage Works Agency
2. Studies on Performance for Sewage Sludge Dewatering Process 10
A. Sugiki, Japan Sewage Works Agency
3. Sewage Sludge Treatment and Disposal as Practiced in Yokohama City —
"Reclamation to Agricultural Land and Green Field" Program — 25
M. Sato, Yokohama City
4. The Treatment and Disposal of Sludge at Toba Treatment Plant 33
5. Yasuda, Kyoto City
5. Sludge Production and Solid Loading Balance in the Nishiyama STP,
Nagoya . 46
T. Annaka and M. Kashiwaya, PWRI, Ministry of Construction
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CHAPTER 1. SLUDGE HANDLING PRACTICE IN JAPAN
1.1 Introduction . .
1.2 Dewatering and Incineration of Sewage Sludge ...
1.3 Research and Technological Development .
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1.1 INTRODUCTION
Ihe number of publicly owned sewage treatment plants in operation in Japan
amounts to 169 as of 1973. The sludge by weight produced out of those plants is
extremely massive. The volume by weight per capita of sludge produced is estimated
in Japan on the basis of Suspended Solid, SS, content in the incoming sewage.
Since the grams per capita of SS in sewage is, at present, found to stand at 40
grams and BOD5 at 44 grams, the sludge volume by weight produced comes up to
36 grams on condition that the removal rate of SS is 80 percent by secondary treat-
ment process. On the other hand, according to a survey conducted by the Japan
Sewage Works Agency, 20 liters of sludge with the solid contents having 2 percent on
an average are being produced per capita a day, indicating a value almost close to the
calculated above. It is known, however, that at some treatment plants where the
activated sludge process is adopted the sludge volume produced exceeds the value
mentioned above approximately by 10 percent.
As for the sludge generated in the treatment process, it is necessary to study
the sludge in preliminary sedimention basin, the excess sludge originating from acti-
vated sludge, the suspended solids existing in recycle flow that grows out of a sludge
treatment system and the material balance of sludge in a treatment system. Recently,
the necessity of surveys of this kind has been keenly recognized and results of such
attempts are partly described in this report from the City of Kyoto and a report on
the Nishiyama Treatment Plant, Nagoya City studied by the Public Works Research
Institute, Ministry of Construction, both to be referred to in this paper.
According to the studies carried out by the Ministry of Construction in 1967,
systems of sludge treatment and disposal can be summarized as follows. The most
prevailing system in use at 169 treatment plants which had been then in operation
was that of "thickening—unaerobic digestion—mechanical dewatering", accounting
for 35 percents while 25 percents was for that of "unaerobic digestion—drying bed"
The treatment plants where sludge was incinerated were only those 10 established in
big cities.
As for disposal systems, the land-filling was adopted at 97 treatment plants and
the sludge from 30 treatment plants are applied on agricultural land as fertilizer
and/or soil conditioner, thus sludge having been returned to the earth at 80 percents
of the total treatment plants.
A study made in 1973 shows that the treatment plants where the system of
"unaerobic digestion—mechanical dewatering" was adopted numbered 77, accounting
for 29 percents of all, while at 55 treatment plants (21 percents) raw sludge was dire-
ctly dewatered by a machine. The number of plants where drying bed was installed
was 24, indicating a decrease at the time of 1967.
In the case of small-scale treatment plants, an increase was noticed in the adop-
tion of aerobic digestion. 34 treatment plants were equipped with incinerator, ac-
counting for 13 percent of the total, and at 17 of them the system of "raw sludge
dewatering-incineration" was adopted while that of "digestion-dewatering-incine-
ration" was at the remaining 17.
Types of filtering / dewatering machine shown in the results of 1973 study are
classified as follows:
- 5 -
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-vacuum filter; 135 treatment plants 381 sets
-filter press; 14 treatment plants 39 sets
-centrifuge; 20 treatment plants 36 sets
Total 169 treatment plants
Also types of incinerating / drying apparatus are as follows:
—vertical multiple-hearth incinerator; 32 treatment plants 39 units
—rotary kiln; 6 treatment plants 6 units
—fluidized bed incinerator; 2 treatment plants 2 units
The reason why the system of "unaerobic digestion—mechanical dewatering
(drying bed)—land-filling" heretofore in use has gradually been switched over to that
of "raw sludge dewatering-incineration—land-filling" is because sludge became nec-
essary to be treated efficiently with the increase in sludge volume produced, as well
as because the necessity arose to reduce as much as possible the volume of sludge to
be disposed, as it became difficult to find available land for sludge disposal. Some
other reasons why the latter system became more in use are considered to be because
—land required for digestion and drying bed turned out to be extremely diffi-
cult;
—the former system requires longer sludge detention time and more labor for
sludge treatment;
—the operation of the former is rather complicated and necessitates skill labor.
However, as the methane gas produced from unaerobic digestion has been put
to use or sludge has been utilized for an agricultural soil conditioner since the oil
crisis from the viewpoint of resources and energy saving, the need to reevaluate un-
aerobic digestion from the sanitary engineering aspect started to be recognized in-
creasingly.
1.2 DEWATERING AND INCINERATION OF SEWAGE SLUDGE
As mentioned above, in respect to types of sludge dewatering machine a great
number of treatment plants were found to have adopted vacuum filters. 4 out of
16 filter presses were in use for dewater sludge after the heat treatment. Ferric cho-
loride (Fe Cb) and lime (Ca(OH)2) were applied for conditioning to dewatering.
Moisture content was 70 to 75 percents in vacuum filter and 55 to 60 percents in
filter press. On the other hand, sludge treated the heat treatment was able to be de-
watered down to the moisture content of 35 to 40%. According to a research made
by the Agency last year on the actual conditions of dewatering devices in use at
medium- and small-scale treatment plants, the volume of chemicals dosed fairly ex-
ceeded the designed value. This seems mainly to have aimed at surer operation of
dewater, but its cause is now under investigation in detail.
Centrifuges were once employed for the physicochemical treatment of night-
soil and also employed for sewage sludge dewatering at some of the sewage treatment
plants. But this type had not been adopted so widely due to the poor solids recovery
and the problems of vibration and noise. Nevertheless, this type of machine is suita-
ble for medium- and small-scale treatment plants on account of such merits that
- it can be compact in size after being kept in a small container for noise and
odor control.
- 6 -
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- it can run automatically in continiously and its maintenance is easy;
- it requires auxiliary facilities less.
This may also be reasoned out from the fact that in those cities where this type
is adopted many of the treatment plants are given the sludge treatment capacity of
more than 4 cubic meters but less than 100 cubic meters. In this type, the moisture
content can be reduced to 80% to 85% by adding polyelectrolytes (or polymer) in
the centrifugal dewatering, and since usual lime and ferric chloride are not applied,
the volume of ash necessarily lessens when incinerating sludge. These merits of cen-
trifuge in the operation and maintenance coupled with a merit in the incineration
have accordingly led big cities to consider the possible adoption of this type.
A new series of this type of machine has begun to be introduced, with its num-
ber of revolutions reduced to 1,200 to 1,900 revolutions per minute and vibration,
noise and durability are improved.
As for incinerators, the reason why many of them are of vertical multiple-
hearth type is because its function has been strengthened so much, after years of
technological improvement, as to be able to treat sewage sludge almost without any
difficulty. Assuming that the moisture content of sludge is 70%, the capacity of in-
cinerator is found to be 5 to 250 tons per day in the case of multiple-hearth type,
4 to 60 tons per day in rotary kiln and 5 to 20 tons per day in fluidized bed type.
Rotary kiln consumes much fuel and seems to be considered inadequate for the
adoption from the standpoint of energy conservation. Fluidized bed incinerator is
suitable for medium- and small-scale plants, since the structure is simplified and the
intermittent operation is economically feasible due to its high heat capacity. Such
defects, however, are pointed out that the volume produced of NOx and powdered
dust is considerable, and the power cost of blower is high as it requires high-pressure
air. Yet, in order to overcome these defects such improvements have been made as
to increase thermal efficiency by providing a spiral flow inside the funance and so
on. As a result, more this type of incinerator are coming to adopt it.
Stack effluent treatment is a matter to be taken into account inevitably when
incineration is brought into focus. As the restrictions on air pollution have gradually
strengther, the treatment of waste gas from sludge incinerators accordingly came to
require more complicated-one. Soot and dust, gases of SOx, HC1, Ch and others in
exhaust gas are considered harmful, and to cope with them scrubbers or washing
with alkali and so forth have been employed. Recently, however, a wet-type electric
precipitator and / or a after burning apparatus have been obliged to be added further
in some areas. In the regions where a strict standard is enforced, the cost of equip-
ment for waste gas treatment has gone so high as to exceed 50 percents of the cost
of total incineration facilities. As a result, under study are new methods, for exam-
ple, of heat treatment by which sludge is dewatered without dosing much of the
chemicals but treatment of cooking liquors, would be required to develop in future.
On account of the fact that considerable energy is consumed in the incineration
of sludge, the introduction of methods based on a new idea of incinerating-with the
least possible energy is now under study. For instance, the first machine of the so-
called CG Process in which sludge is evaporated after being mixed with oil is selected
for sewage treatment plant of Fukuchiyama City, and a Lucas-type incinerator in
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Maebashi City, both being under construction at present. The Agency has been
studying the performances of sludge dewatering since last fiscal year, of which result
will be partly reported to this conference, and starting this fiscal year another study
on the performances of incinerators and waste gas treatment facilities was decided to
be carried out. This program is aimed to produce basic data for the preparing of ra-
tional design criteria, on the standpoint of systematic approach.
As for new-type facilities for sludge treatment set up in the cities of Fukuchi-
yama and Maebashi, it is planned by the Agency to analyse their process perform-
ance and to evaluate them, upon coming into actual operation.
1.3 RESEARCH AND TECHNOLOGICAL DEVELOPMENT
With the increase in the volume of sludge to be disposed, the Ministry of Con-
struction, Japanese government, decided to augment to a great extent the budget for
study and research on sludge treatment and disposal starting this fiscal year.
Sludee has been utilized for an agricultural fertilizer or a soil conditioner since
long time ago. The Japan Society of Civil Engineers has been studying sewage
sludge application on agricultural land since 1969.
The volume of sludge to be applied depends upon what plant to be cultured,
but in the case of paddy rice the upper limit of application was considered to be 100
kilograms per ha., and the desirable rate of an application to vegetables and fruit
trees, etc. was found to be more or less 250 kilograms per ha. It is of necessity,
however, to make clear how soils and plants will be affected by heavy metals con-
tained in sludge. The Japan Society of Civil Engineers studied this subject for two
years, and starting this fiscal year the Agency is supposed to carry out an ecological
study on the effect over soils and plants when sludge is applied continuously.
Yokohama City started a study on the use of sewage sludge on agricultural land
in 1971 and constructed a drying facility based on the study results. That facility is
now in practical use and further detail will be given in the chapter III.
Various attempts to recover the useful ingredients in sludge have been made so
far, and the one to utilize an available gas after drying sludge up by distillation began
to be studied also in our county.
The supernatant originating from sludge digestion and heat treatment used to
be sent back to a main plant and treated there. As far as the heat treatment superna-
tant is concerned, it is known that in Sapporo City and so forth a considerable por-
tion can be removed through biological treatment. However, this kind of supernatnat
contains a sizable amount of phosphorus and nitrogen aside from organic matters,
and when the supernatant is sent back to a main plant those phosphorus and nitro-
gen are to. -be discharged fairly much into the treated water. Places where the super-
natant seems necessary to be treated separately from the standpoints of waste water
treatment and eutrophication measures are increasing in number. The Agency has
started a study and research on this problem since the beginning of this fiscal year.
On the other hand, the Public Works Research Institute has begun to study how
to recover organic matters from the supernatant to utilize for carbonic resources for
biological denitrification.
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The development of treatment and disposal method of tertiary-treatment sludge
is one of the important subjects to be studied more thoroughly in future. The Public
Works Research Institute has already started a basic research on the recovery of
tertiary-treatment sludge, etc., and also the Agency is conducting a study and re-
search on the dewatering of sludge from a pilot plant at the Lake of Biwa, Shiga
Prefecture. This paper covers hereinafter the following contents.
II. Studies on Performance for Sewage Sludge Dewatering Processes
III. Sewage Sludge Treatment and Disposal in Yokohama—Agricultural Land Appli-
cation.
IV. Sludge Treatment and Disposal in Toba Sewage Treatment Plant, in Kyoto
V. Material Balance of Solids in Nishiyama Sewage Treatment Plant in Nagoya City
9 -
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CHAPTER 2. STUDIES ON PERFORMANCE FOR SEWAGE SLUDGE
DEWATERING PROCESSES
2.1 Purpose. 11
2.2 Statistics 11
2.2.1 Sewage Plant and Dewatering Equipment . 11
2.2.2 Thickening 11
2.2.3 Sludge Cake and Filtrate 12
2.2.4 Conditioning.. 12
2.2.5 Performance 12
10 -
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2.1 PURPOSE
At present, throughout Japanese main lands, 426 sewage plants are under opera-
tion. Recently a activated sludge process becomes a standard means to cope with
urban waste water. The process produces a large amount of sludge which requires
another treatment. Therefore, almost all of the sewage plants have sludge dewatering
equipments.
Although design parameters of the dewatering machines are provided in some
manuals, performances of the machines are not certain. Once machines are set up,
not only design personnels but also regulatory agencies lost interests in them. Opera-
tional experience and performance data are accumulated only locally. As a result,
design technology of the machines does not improve but still remains under-develop-
ment. A procedure to select the proper type which is most suitable for the local con-
ditions is "the rule of a thumb". If his machine works properly, he is in bonanza.
It is a little more than an art to determine his type.
Through the year of 1975, sewered population will exceed twenty percent.
The rest 80 percent people are scheduled to be sewered within few years. Therefore
Japan is an attractive market for sewage equipment manufacturers. Their advertise-
'ment is like a kaleidoscope. This adds another confusion to local personnels.
Japan Sewage Works Agency is responsible to provide municipalities with engi-
neering consultations. We launched a research project aiming primarily to establish
"a standard procedure to select sludge dewatering equipment and to make a specifi-
cation of the dewatering machines required for satisfying the local conditions"
The first step approaching to this goal is to overview the present dewatering
practices. Our staffs visited 170 sewage plants and collected operational data to build
a statistics which will show a rough sketch of the sewage sludge dewatering practices
in Japan.
2.2 STATISTICS
2.2.1 SEWAGE PLANT AND DEWATERING EQUIPMENT
The main process for waste water treatment and design capacity of the 170
plants surveyed are summarized in Table 2.1. 64% of the total 170 plants are de-
signed on the basis of the standard activated sludge process and 28% are of the step
aeration process. A majority of the small plants whose capacity is less than 5,000
m3 /day has the standard activated sludge process. A half of the middle class plants
where capacity ranges from 20,000 to 100,000 m3/day has the standard activated
sludge and the rest half has the step aeration.
The continuous rotary vacuum filter is the most commonly used device for
dewatering sewage sludge. This device is used widely in the small and large sewage
plants. 80 percents of the 170 plants are equiped with this (Table 2.2).
2.2.2 THICKENING
Solids concentration in mixture of primary and secondary sludge ranges widely.
Annual average values of the concentration are distributed from 0.5 percents to 3.0
percents. It is inefficient to feed the dewatering equipment. They are too thin and
should be concentrated.
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51 plants have only thickeners and 43 plants have primary thickeners, digesters,
elutriation, tanks, and secondary thickeners. The digesters are found in 101 sewage
plants. As a general rule the small sewage plants have only the thickener as a pre-
treatment equipment. The digesters are practiced in a half of the large sewage plants
(Table 2.3).
A number of the centrifuge that follows the digestion tanks is large. The half
number of the rotary vacuum filters is fed with digested sludge. All the filter press
and the rest half vacuum filters are fed with mixture of raw primary and secondary
sludge (Table 2.4).
4 percent solid concentration is a standard value for design of sludge dewatering
equipment. However, the annual average of this value in 102 plants exceeds this
standard value (Table 2.5).
No significant difference in solid concentration between digested and undi-
gested sludge appears.
As compared with the other sludge, thermal treated sludge has conspicuous
discrepancy in the solid concentration.
2.2.3 SLUDGE CAKE AND FILTRATE
When rated by moisture concentrations included in the dewatered cake, the
filter press comes the first place. This can yield easily the cake of which moisture
content is less than 50 percent. The running up is the centrifuge or the vacuum fil-
ter, depending on local conditions (Table 2.6).
Suspended solid concentration in filtrate produced by the vacuum filter is gen-
erally less than that by centrifuge. The concentrations is no greater than 1000 mg/1,
except some extra ordinal cases. Seven cases that the SS concentration in the filtrate
exceeds 3000 mg/1 are observed.
2.2.4 CONDITIONING
, Lime and ferric chloride are the most commonly used chemicals for the purpose
of sludge conditioning in advance of either the vacuum filter or the filter press; 101
out of the 135 vacuum filters are fed with the sludge which is conditioned by using
the lime and ferric chloride and so does 6 out of the 13 filter press.
On the basis^of a dry solid, 25 percent and 10 percent are average feeding rates
of the lime and the ferri; chloride respectively. When lime dosage increases, propor-
tionally the ferric chloride dosage increases (Table 2.7). Even for conditioning di-
gested sludge, the same amount of these chemicals as for conditioning the undigested
sludge is widely used.
Polymer is the only chemicals that are used to condition sludge for the centri-
fuge. There is no plant where inorganic coagulant is dosed for centrifuge purposes.
2.2.5 ' PERFORMANCE
Comparisons of design capacities and actual performances in 108 vacuum filter
plants are shown on Table 2.8. The case that an amount of sludge actually handled
is greater than the originally designed capacity is observed in 28 vacuum filter plants
and 4 filter press plants.
One of the difficult decisions in selecting the centrifuge is how to satisfy both
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efficiency in SS recovery and efficiency in dewatering. Usually an increase in the SS
recovery results in an decrease in the dewatering efficiency. If the fed sludge concen-
tration is more than 20,000 mg/1, more than 80 percents SS recovery rate is ex-
pected.
61 dewatering plants are operated between 3 and 6 hours daily, 35 are so less
than 3 hours and 36 are between 6 and 12 hours. Only 11 plants are operated for
24 hours every day.
An amount of raw sludge produced is closely related to an amount of raw
sewage to be treated. A correlation coefficient between the amounts of raw sewage
and raw sludge is 0.61 (Fig. 3.1). Every one cubic meter of the raw sewage treated,
about 20 liters of the raw sludge are produced during the course of the primary and
the secondary treatment.
The raw sewage rate to be treated and the power consumed by either of the
three dewatering equipments are in a linear correlation (Fig. 3.2). A magnitude of its
tangential value is different, depending on the equipments; 0.037 KWH/m3 for the
vacuum filter, 0.0123 KWH/m3 for the centrifuge, and 0.0546 KWH/m3 for the fil-
ter press. A energy consumption per unit solid is greatest for the filter press, middle
for the vacuum filter, and least for the centrifuge.
13
-------
Table 2-1 Relationship between Design Capacity and Process
^^^-\^^ Process
Design ^^~^^^^
capacity (m3 ) ^^~^\^^
0 ~ 5,000
5,000- 10,000
10,000- 20,000
20,000- 50,000
50,000- 100,000
100,000-200,000
200,000 - 500,000
500,000 -
Total
1
14
11
6
8
10
6
8
1
64
2
0
0
0
2
0
0
2
0
4
3
1
1
4
5
1
0
0
0
12
4
0
0
0
1
1
0
0
0
2
5
2
4
* 3
19
10
5
4
2
49
6
0
0
1
1
1
0
0
0
3
7
3
4
4
7
1
0
0
0
19
8
0
0
0
0
4
3
2
0
9
9
1
0
0
0
0
0
0
0
1
10
0
0
0
2
0
0
0
0
2
11
0
0
0
1
0
0
0
0
1
1?
0
0
0
1
0
1
0
0
2
n
0
0
0
1
0
0
0
0
1
14
0
1
0
0
0
0
0
0
1
Total
21
21
18
48
28
15
16
3
170
Note: 1 : Conventional activated sludge process
2 : Modified aeration process
3 : High rate aeration sedimentation process
4 : 1 &3
5 : Step aeration process
6 : 1&5
7 : Trickling filter process
8 :Hain sedimentation
9 : Single Stage Digestion
10 : Neutralization
11 : 3&7
12 : 5&8
13 : 1&7
14 : Others
- 14 -
-------
Table 2-2 Relationship between Design Capacity and Type of Dewatering Machine
\Type of dewatering
NS. machine
Design ^~~--\^^
capacity (m3) ~\^^
0- 5,000
5,000- 10,000
10,000- 20,000
20,000- 50,000
50,000- 100,000
100,000 - 200,000
200,000 - 500,000
500,000 -
Total
Vacuum filter
17
17
13
42
19
11
13
3
135
Centrifuge
3
3
5
3
6
0
1
0
21
Filter press
0
1
0
3
3
4
2
0
13
Others
1
0
0
0
0
0
0
0
1
Total
21
21
18
48
28
15
16
3
170
15 -
-------
Table 2-3 Relationship between Treatment System and Capacity
^""""^^^^ Capacity (average)
Treatme^^S^y
system ^^~~~~-^^^
1-2-3-4
1-2-3
1-2-4
1-2
1-3-4
1-3
1-4
1
2-3-4
2-3
2-4
2
3-4
3
4
Others
Total
0
~ 5,000
6
1
0
5
0
0
3
15
2
1
0
1
0
0
0
7
41
5,000
~ 10,000
2
2
0
4
0
0
1
2
2
0
0
2
0
0
0
0
15
10,000
~ 20,000
6
3
0
1
0
0
0
8
1
1
0
2
0
0
0
1
23
20,000
~ 50,000
14
5
0
2
0
0
1
14
0
2
0
1
0
0
0
0
39
50,000
~ 100,000
7
3
1
1
0
0
1
10
1
3
0
1
0
0
0
2
30
100,000
~ 200,000
4
1
1
3
0
0
1
2
0
1
0
0
0
0
0
0
13
200,000
~ 500,000
2
2
0
2
0
0
1
0
0
0
0
0
0
0
0
0
7
500,000
2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
Total
43
17
2
18
0
0
8
51
6
8
0
7
0
0
0
10
170
Note: 1 : Thickner
2 : Digestion tank
3 : Sludge elutriation tank
4 : Sludge storage tank
-------
Table 2-4 Relationship between Treatment System and Type of Dewatering Machine
\Type of dewatering
^•^_ machine
system ^"~~\^
1-2-3-4
1-2-3
1-2-4
1-2
1-3-4
1-3
1-4
1
2-34
2-3
2-4
2
3-4
3
4
Others
Total
Vacuum filter
39
16
2
13
0
0
6
38
6
1
0
3
0
0
0
5
135
Centrifuge
2
0
0
5
0
0
1
4
0
1
0
4
0
0
0
4
21
Filter press
2
1
0
0
0
0
1
8
0
0
0
0
0
0
0
1
13
Others
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
1
Total
43
17
2
18
0
0
8
51
6
8
0
7
0
0
0
10
170
Note: 1 : Thickner
2 : Digestion tank
3 : Sludge elutriation tank
4 : Sludge storage tank
17
-------
Table 2-5 Comparison of Solid Concentration between Digested and Raw Sludge
Solid concentration
(%)
0- 1
1 ~ 2
2- 3
3- 4
4- 5
5-6
6- 7
7- 8
8- 9
9-10
10-15
15-20
20-25
25-
No data
Total
Digestion
0
1
10
17
21
17
8
6
j
1
5
0
0
0
9
98
No-digestion
0
0
9
10
13
14
3
7
0
0
2
1
1
0
12
72
Total
0
1
19
27
34
31
11
13
3
1
7
1
1
0
21
170
- 18 -
-------
Table 2-6 Cake Solid Concentration after Dewatering
\Type of dewatering
x__ machine
Cake ^~~~~~~~-~-~-__^
solid concentration^
(%) \
0-15
15-20
20-25
25-30
30-35
35-40
40-45
45-50
50-55
55 ~
No data
Total
Vacuum filter
0
10
44
39
14
8
0
1
0
1
18
135
Centrifuge
0
3
6
6
2
0
0
0
0
0
4
21
Filter press
0
1
1
0
1
3
0
3
1
2
1
13
Others
0
1
0
0
0
0
0
0
0
0
0
1
Total
0
15
51
45
17
11
0
4
1
3
23
170
19
-------
Table 2-7 Dose of Fe3+and Ca2+in Vacuum Filter
^~-\_Ca^+dose (%)
Fe3+dose (%T"^\^
0~ 5
5-10
10-15
15-20
20-25
25-30
30-40
40-50
50-
Total
0-10
19
1
20
10-20
10
13
1
24
20-30
6
11
5
22
30~40
2
10
5
2
1
2
22
40-50
2
1
5
8
50-60
2
2
2
2
1
1
10
60-70
0
70 - 80
1
1
80-90
1
1
2
90 - 100
-0
100-
1
1
2
Total
42
38
18
3
4
3
1
1
1
111
o
:
No data 24
-------
Table 2-8 Relationship between Solid Concentration and Yield of Vacuum Filter
N. Actual Yield, ^
c r>^esi§n YielrT
Solid x.
Conc.C^rN^
0- 1
1 ~ 2
2- 3
3~ 4
4- 5
5- 6
6- 7
7- 8
8~ 9
9-10
10-
Total
0-10
1
1
1
3
10-20
1
1
2
4
20-30
1
2
4
1
8
30-40
1
3
2
1
1
8
40-50
5
2
2
5
1
1
16
50-60
4
4
1
9
60-70
1
3
5
2
1
12
70-80
1
1
2
3
2
9
80-90
1
1
1
2
2
7
90 - 100
1
1
1
1
4
100-
1
1
3
4
8
2
4
2
1
2
28
Total
0
1
11
20
24
23
8
11
2
1
7
108
I
to
No data 27
-------
INJ
tNj
Sludge volume produced (m3)
4000
50000
Correlation coefncienl. 0.6105
300000
Capacity (in3)
Fig. 2-1 Relationship Between Sludge Volume and Capacity (Vacuum filter)
-------
I
to
» Vacuum filter
Filter press
Centrifuge
Fig. 2-2 Relationship Between Capacity and Power Consumption
-------
I
1NJ
* Vacuum filter
4 Filter press
0 Centrifuge
1000 ,000
Fig. 2-3 Relationship Between Sludge Volume and Power Consumption
3000
Sludge volume produced (m3 )
-------
CHAPTER 3
SEWAGE SLUDGE TREATMENT AND DISPOSAL AS PRACTICED IN
YOKOHAMA CITY
-"RECLAMATION TO AGRICULTURAL LAND AND GREEN FIELD"
PROGRAM -
CONTENTS
1. Present Status of Sewage Sludge Treatment/Disposal 26
2. Problems Associated with Sewage Sludge Disposal 28
3. "Reclamation to Agricultural Land and Green Field" Program 28
3.1 Size of "Reclamation to Agricultural Land and Green Field" Program . .29
3.2 Sludge Dryer Installation 29
3.3 Outline of Installation 31
3.4 Construction and Operation/Maintenance Costs 31
3.5 Properties of Dried Sludge 32
25
-------
Sewage Sludge Treatment and Disposal as Practiced in Yokohama City
— "Reclamation to Agricultural Land and Green Field" Program —
1. PRESENT STATUS OF SEWAGE SLUDGE TREATMENT/DISPOSAL
In the sewerage plan of Yokohama City, constructing ten sewage treatment
plants in nine treatment districts is planned, and so far five are already in service. At
these treatment facilities, secondary treatment by activated sludge process is
performed, and the sludge produced from these facilities today amount to, in terms
of concentrated sludge (moisture content 96%), roughly 600,000 cubic meters
annually. Treatment and disposal methods practised are: (1) unaerobic digestion
process at two plants and wet air oxidation at one plant, followed by (2) dehydration
in both cases, and (3) disposed to, in most part, dumping yards of the City as land fill.
Characteristics of sludge cakes: those treated by unaerobic digestion process has
a moisture content of 70 to 75% (carbide slurry and ferric chloride added) with
volatile matter 25 to 30%; those by wet air oxidation has a moisture content of about
40% with volatile matter 10 to 15%.
Given in Fig. 3 — 1 is the outline of sewage sludge treatment/disposal process and
major sludge treatment facilities.
- 26
-------
Fig. 3-1 Sewage sludge treatment and disposal process
Concentration -
-•- Unaerobic digestion •
• Dosage
(cabide slurry
ferric chloride)
•Wet air oxidation -
Elutriation -
-Dosage —Vacuum dehydration -
(cabide slurry
ferric chloride)
Drying
Dosage —
(polymer)
• Centrifugal -
dehydration
• Press dehydration -
Reclamation to agricultural
land and green field
• Land fill
Reclamation to agricultural
land and green field
Land fill
-------
2. PROBLEMS ASSOCIATED WITH SEWAGE SLUDGE DISPOSAL
The volume of sewage sludge produced in Yokohama City roughly doubled in
three years since 1970. Sludge cakes produced presently amounts to 40,000 cubic
meters annually, and it is estimated to increase by tenfold, or 400,000 m3, by 1985.
This sludge is now, as it was described earlier, dumped over dumping yards
within the City, however, due to rapid expansion of dwelling districts, distant
dumping yards are being sought, and with increased traffic conditions within the City,
its transportation is found more and more difficult these days. Moreover, it is very
difficult to find new inland dumping yards today. And at the present dumping yards,
disposed cakes tend to become a very soft mud as they quickly absorb a large
quantity of water, posing a troublesome problem to proper land fill operations.
Difficulties in handling, bad-smelling and leachate out of the sludge cake are among
the associated problems for which we are under the pressure to find other means of
disposal.
3. "RECLAMATION TO AGRICULTURAL LAND AND GREEN FIELD"
PROGRAM
It is the principal rule to follow, in its end, that all sewage sludge is returned to
the ground by accomplishing it in harmony with the Nature's cyclic process of
materials. It is desirable, therefore, to dispose sewage sludge to the ground or to the
ocean, in a manner that will not disturb, or helps the ecosystem of the Nature.
For a coastal city like Yokohama, although we cannot choose but to rely on
returning it to the ocean and reclaiming a foreshore while concentrating our efforts
on finding inland dumping yards, we must work to establish a disposal scheme
primarily based on returning to the ground and reclamation to agricultural and green
field, as a more essential solution to this problem.
Since sewage sludge contains nitrogen and phosphorus and is rich with organic
matter, unlike chemical fertilizers, when it is returned to the soil, its benefit is not
limited to serving as an enrichener, but to aid in producing an environment necessary
for the growth of bacteria in the soil, subsequently creating an airy soil construction
desirable for vegitation with good retention of moisture.
A three year study, from 1971 to 1974, that Yokohama City conducted in
cooperation with the Tokyo University of Education reveals that it could be a
hopeful fertilizer with about the same dressing effectiveness as matured compost,
whereas it is slow acting to dry field rice plant and barley when compared with
chemical fertilizers.
As for its dressing effectiveness to cyclamen, a garden plant, it is found to be
much the same as that of the soil customarily used, it is a slow-acting but
long-standing fertilizer. When sludge is used to lawn soil, it is found that lawn's
growth in height and in the area of its leaves increased with the increase of its sludge
appliction.
For acceptable application of sewage sludge to the soil, ease of handling, storage
and transportation, and freedom from discomfort are required. Pathogenic bacteria
and weed seeds must be sterilized, too.
For these reasons, it is desirable that, following dehydration processing, sludge
be dried by dryers to reduce its moisture content further until granular sludge is
obtained.
In Yokohama City, operational sludge dryers were installed in the Nambu
Sewage Treatment Plant in 1973 and 1974 as part of promoting "the reclamation to
agricultural land and green field" program.
- 28 -
-------
3.1 SIZE OF "RECLAMATION TO AGRICULTURAL LAND AND GREEN
FIELD" PROGRAM
Before sludge reclamation to agricultural land and green field is carried out, such
factors as secondary public nuisance by heavy metals, or plants' absorption of heavy
metals and their accumulation in the soil, must be thoroughly studied. Sludge
application therefore should be carefully selected, and for the time being, limiting its
application to greenyard of parks in the City, an annual desposition of 2,600 tons of
dry sludge (equivalent to roughly 24% of the sludge cakes produced) is planned.
3.2 SLUDGE DRYER INSTALLATION
Digested sludge is added with polymer and then dehydrated by a centrifuge
before it is fed into the sludge dryer system.
The project size of installation: two sludge dryer systems to be run on a
six-hour-a-day basis, each with a capacity of 1,300 tons of dried cludge output. One
system is to be installed initially. If the installation is operated on a full scale, it
would have the capability of producing some 10,000 tons of dried sludge annually.
The drying system is schematically represented in Fig. 3-2.
29
-------
Fig. 3-2 Flow diagram of sludge dryer
u-i
o
Cyclone
80% dust catch
Scrubber
90% dust catch
Deodoreizer
Temp : 700° C
Fuel : Digestergas 743Nm3/hr
(Kerosene 530«/hr)
Exhaust stack
Gas temp. 700°C
Height 15m
Dewatered sludge
strage tank
Truck loader
Measuring & pouring machine
Capacity : 3,500 Kg/hr (Cake TS 25%)
1,006 Kg/hr (Dried Cake TS 13%)
Fuel : Digester gas 372 Nm3 /hr
(Kerosene 287 1/hr)
-------
3.3 OUTLINE OF INSTALLATION
The drying system consists essentially of the following four elements:
a) Sludge Feeder
Dehydrated sludge is continuously fed to the dryer with a variable-speed screw
conveyor in a batch process.
(b) Dryer
While moving slowly in the axial direction, sludge is exposed to heated air of
about 900° C blown in the same direction as the drum rotates slowly. Temperatures
within the drum are so controlled that it is approximately 900°C at the entrance;
about 1 20° C at the outlet.
Sludge is scraped upward to the upper part of the drum with blades attached on
the inner wall of the drum, and is crushed by rotating rods as it falls off from the
upper part of the drum. By this repeated process of crushing, sludge gets greater
surface area while moving from one end to the other in the drum, and it contacts with
the hot air for about 40 minutes. Obtained is granular sludge with a moisture content
of about 13%.
For the best possible utilization of energy, primarily digestion gas is used as
fuel-another benefit of eliminating air pollution by other fuels.
(c) Dry Sludge Storage/Bagging Unit
An automatic measuring/bagging machine packages dry sludge in polyethylene
bags in a 20 kg batch.
(d) Exhaust Gas Clarifyer
Cyclone dust catchers and a scrubber are arranged in series. With 98% of dust
caught by this arrangement, the dust content of air released to the atmosphere is
0.17 g/Nm3, or 60% below the 0.4 g/Nm3 requirement specified under the Kanagawa
Prefecture Public Nuisance Prevention Act.
Deodorization of exhaust gas is accomplished through oxidation-decomposition
by heating it to about 700° C. The deodorization furnace temperature is controlled to
700°C. At this temperature, nitrogen oxides generation is reduced to a minimum.
Exhaust gas is free of sulfur oxides when digestion gas is used. Their discharge
with the use of kerosene is 2.245 m3/h, 50% below the 4.1 Nm3/h requirement.
Calories necessary for the deodorization are: with digestion gas, 4,454,000 kCal
per hour with a fuel consumption of 743 Nm3 per hour; with kerosene, 530 liters per
hour.
3.4 CONSTRUCTION AND OPERATION/MAINTENANCE COSTS
Listed below is the breakdown of construction cost of the sludge dryer
installation:
Dryer system 165,900,000 yen
Electrical system 80,400,000 yen
Buildings 108,384,000 yen
Miscellaneous 1,390,000 yen
Total 356,074,000 yen
Annual cost for operating the dryer installation on a 3-personnel operator,
6-daytime-hour run basis is estimated as follows:
Personnel cost 9,000,000 yen
Electricity cost 2,202,000 yen
Repairs, expendables 6,900,000 yen
Equipment lease (fork trucks) 1,200,000 yen
Depreciation of installation 15,027,000 yen
31
-------
Fuel cost 0 yen
Total 34,329,000 yen
With an annual dried sludge production of 1,300 tons, the dehydrated sludge
costs about 7,600 yen per ton.
3.5 PROPERTIES OF DRIED SLUDGE
Composition of sludge before and after drying processing as a fertilizer, is given
in Tables 3 — 1. You may notice that components remain much the same before and
after processing in the dryer. Dry sludge generally has a moisture content of 5 to 16%
with granular sizes ranging between 1.0 and 3.3 millimeters in diameter.
Tables 3—1 Compositon of sludge before and after drying processing as a fertilizer
Item
Total Solids
Volatile Solids
Phosphorus (P2 O5 )
Patassium (K2 O)
Calcium (CaO)
Magnesium (MgO)
Nitrogen (Kjeldahl)
pH
Dehydrated Sludge
23.8%
39.7
3.2
0.77
2.9
1.0
3.3
7.45
Dried Sludge
90.0%
35.8
3.1
0.75
3.0
1.0
2.9
7.17
Note
Weight % of Sludge
Weight % of Solid
Weight % of Solid
Weight % of Solid
Weight % of Solid
Weight % of Solid
Weight % of Solid
Weight % of Solid
32
-------
CHAPTER 4. THE TREATMENT AND DISPOSAL OF SLUDGE AT
TOBA TREATMENT PLANT
4.1 Introduction 34
4.2 Outline of Sludge Treatment Facilities
4.3 Operation Data of Sludge Treatment Facilities 36
Solids Balance at Each Treatment Process 36
Thickening Tanks 38
Digestion Tanks 39
Dewatering Facilities 40
Incinerators ' 41
4.4 Some Considerations on Toxic Substances and Heavy Metals in
Disposing Sludge 42
Toxic Substances in the Exhaust Gas from the Incinerators and the
Countermeasures 42
Effluence Test of Toxic Substances and Others from Ash 42
4.5 Researches on Sludge Ash for its Reuse 45
Utilization for Soil Conditioners 45
Use as a Material for Road Construction 45
- 33 -
-------
4.1 INTRODUCTION
Kyoto is an inland city located on the midstream of the Yodo River. On the
lower reaches of the river there is a group of cities centering around Osaka, and
the river is the only source of water for approximately ten million people in those
cities. The river water, therefore, is widely used for drinking, farming, and
industries.
Aiming to ameliorate the life environment of the citizens and to prevent
water pollution of the Yodo river, the City of Kyoto has been endeavoring to
construct its sewerage system. As of March 1975, the city's sewer system covers
45% of the urbanized area of the city. That is, 48% of the total citizens share in
the benefit of the system. By the year 1985 the system is to cover the whole of
the urbanized area of the city.
At present the sewage is treated by three plants, namely Toba, Kisshoin, and
Fushimi Plant. (Table 4.1) Of the three, the Toba Plant is the biggest. The present
conditions of the sludge treatment at Toba Plant are described below.
Table 4.1 Present Conditions of the Three Plants
Name of
Plant
Toba
Kisshoin
Fushimi
Treat't
Capacity
m3/d
570,000
92,900
55,000
Qty. of
Inflow
m3/d
388,400
94,300
22,100
Treat't
Process
Activated
Sludge
Process
Activated
Sludge
Process
Activated
Sludge
Process
Sludge Treatment Process
Thickening- Anae robic Dige st ion- Vacuum
Filtration -^ Incineration-Reclamation
or Thickening-Vacuum Filtration-!
Pumping to Toba Plant
Thickening-Vacuum Filtration- Transport
to Toba Plant
Note: The quantities listed above are the average inflow at the time of dry weather during
the period from April 1974 to March 1975
4.2 OUTLINE OF SLUDGE TREATMENT FACILITIES
At the Toba Plant, not only the sludge produced at the Plant but the night
soil brought into the digestion tanks and the sludge pumped from the Kisshoin
Plant are treated. As shown by Figure 4.1, before the sludge becomes ash and is
used for landfill, it is digested, dewatered and incinerated, or raw sludge is
dewatered and incinerated. The sludge cake dewatered at the Fushimi Plant is also
transported to the Toba Plant, where it is incinerated. Thus all the sludge
produced at those three plants is in the ultimate treated and disposed of at the
Toba Plant.
Table 4.2 shows an outline of the sludge treatment facilities.
34 -
-------
Figure 4.1 Flow Diagram of Sludge Treatment
i Raw
Excess
1 Sludge
1
1
I
1
Sludge fr.
•Gsshoin P.
Night Soil
Collected
i
L
i
Digestion Elutriation
)
Methane Gas
1
Desulfurizerl — 5-!rd;>, -•*•
Tank
uewaieieu
Cakes fr.
Fushimi P.
i
Vacuum V |
~S Filter -Hlncinerator| {
1
1
I
1
1
Utilization for Fuel |
_l
• Landfill
Table 4.2 Outline of the Sludge Treatment Facilities
1. Sludge Thickening Tanks
Type
Diameter
Water Depth at Wall
Number of Tanks
Capacity, Each Tank
I
Circular Tank
20.0m
3.0m
2
966m3
n
Square Tank
17.0m x 17.0m
3.6m
2
1,160m3
ffl
IV
Circular Tank
20.0m
3.0m
4
942m3
2. Sludge Digestion Tanks (Two Stage Digestion)
Type
Diameter
; Water Depth at Wall
Water Depth at Center
Heating System
Agitating System
Number of Primary
Digestion Tanks
Number of Secondary
Digestion Tanks
Capacity, Each Tank
Temperature
Detention Period
I
n
ra
IV
Cylindrical. Tank with Cone Bottom and Fixed Cover
25.0m
5.2m
9.2m
25.0m
8.2m
ll.lm
Heat Exchanger
25.0m
8.2m
ll.lm
Steam Blowing
Gas Agitator
1
1
3, 600m J
3,090m3
30°C
30 days
2
2
3
1
3
1
4,400m3
30°C
30 days
22.5 days
- 35 -
-------
3. Vacuum Filters
Type
Diameter of Drum
Length of Drum
Surface Area of Filter
Rate of Filtration
Number Installed
i n
Belt Filter
3.5m
4.2m
47m2
17.5 kg dry solid/m2
hr
8 12
4. Incinerators
Type
Outside Diameter
Height
Burning Temperature
Number of Stages
Capacity, Each
Number Installed
Multiple-Hearth Type
4.35m
10.04m
5.10m
1 1 .34m
6.78m
12.35m
800°C
8
60t sludge cake/day
2
1
150t sludge cake /day
3
4.3 OPERATION DATA OF SLUDGE TREATMENT FACILITIES
4.3.1 SOLIDS BALANCE AT EACH TREATMENT PROCESS
The average daily figures of solids balance at each treatment process at the
Toba Plant during the period from April 1974 to March 1975 are shown by
Figures 4.2, 4.3, and 4.4. The suspended solids in the inflowing sewage is 57 tons.
Through the sewage treatment process, 14.7 tons of excess activated sludge is
synthesized from the soluble matter. Further the solids in the wastewater to be
returned to the sewage treatment facilities from the sludge treatment facilities are
added to it. Thus the total quantity of the sludge solids that are sent to the
thickening tanks becomes 127.3 tons.
Besides the aforementioned, 9 tons of sludge solids is sent to the thickening
tanks from the Kisshoin Plant, 6.5 tons of solids in the night soil is thrown into
the digestion tanks, and 2.3 tons of dewatered cakes is sent to the incinerators
from the Fushimi Plant. Thus all the sludge produced at those three plants is
treated and disposed of by the Toba Plant.
As shown by Figure 4.4, altogether 136.3 tons of solids is sent to the
thickening tanks, and out of the 126 tons efflux 57.2 tons is fed to the digestion
tanks and the other.68.8 tons is sent to the dewatering facilities. Of the sludge
solids fed to the digestion tanks, 12.5 tons is gasified and other 30.5 tons is sent
to the dewatering facilities as digested sludge. By the incinerators, altogether
360.4 tons of dewatered cakes is incinerated and 48.1 tons of ash is produced.
The 360.4 tons of cakes consist of 261.6 tons of raw sludge cakes, 88.8 tons of
digested sludge cakes, and 10 tons of cakes sent from the Fushimi Plant.
The solids in the wastewater from the sludge treatment facilities are 10.3
tons from the thickening tanks, 20.7 tons from the digestion tanks, and 29.6 tons
from the dewatering facilities.
- 36 -
-------
Figure 4.2 BOD and SS Balance at the Sewage Treatment Process
Inflowing Sewage
SS
BOD
"57.0 t/dl
85.0~17dl
SS
117.6 t/d
BOD 117.0 t/d
fr. Sludge Treatment System
Excess Sludge
I
Primary Sedimentation
Tank
SS| 127.3 t/d|
SS
BOD
35.3 t/d
52.7 t/d
Removal
70%
55%
to Sludge Treat't System
Aeration Tank
~~|
- Final Sedimentation Tank I
"
SS
BOD
5.0 t/d
6.0 t/d
Removal
86%
89%
Total
Removal
91%
93%
Effluence
Figure 4.3 Solids Balance at Toba Plant
Inflowing Sewage
II
157.0 t/d |
I
Wastewater
(60.6 t/d|
Sewage Treatment Facilities
Raw Sludge
I
|127.3 t/d|
V V
Sludge Treatment Facilities
Incineration
I
[72.0 t/dl
Landfill
Raw Sludge fr.
Kisshoin Plant
Night Soil
Collected
Digested & Gasified
J12.5 t/d|--— >
Dewatered Cakes
fr. Fushimi Plant
37 -
-------
Figure 4.4 Solids Balance at the Sludge Treatment Process
toTobaPlant
[Total wast ewater
TobaPlant
1127.3 t/d|
|60.6 t/d] 13&.J
i
Overflow
u, -1 1 n 1 t /H 1 -'
r |iu.j i/u|
1
i
'Supernatant
1
'Supernatant
1 L_
1
'Filtrate etc.
rl!7 6 t/dl- T
126.0
1
140.3 t/d]
t/d
Kisshoin Plant
19.0 t/dl
ng Tank
"t/d]
116.9 t/d|
Night Soil
Collected
16.5 t/dl
|23.4 t/d|
Digestion
Tank
(Sewage Sludge)
|20.4 t/d|
Gasified
i
Digestio
(Sewage
Night Sc
Gasified
H4/7 t/dh-
I
n Tank
Sludge & U
il)
Qai "t/dj
i 168.8 t/dl
1
i
1 i
30.5
t/d|
. 1 Elutriation Tank
i
[ -- Storage Tank |--
I r-J
i
Storage Tank]
i L -j Vacuum Filter fl | ' ] Vacuum Filter I| Fi
I Filtrate etc. '
112.0 t/d '
Solids
Cakes
56.8 t/d Solid
261.6 t/d Cake
s 12.9 t/d So
5 88.8 t/d Ca
ishimi Plant
lids 2.3 t/d
kes 10.0 t/d
Solids
Cakes
72.0 t/d
360.4 t/d
| Incinerator |
Ash | 48.1 t/d |
T
Landfill
4.3.2 THICKENING TANKS
The thickening tanks are divided into four groups. The operation data of the
tanks are shown by Table 4.3. The average concentration of the solids in the
sludge coming from the primary sedimentation tanks is 1.1 to 1.5%. The average
concentration of the solids in the thickened sludge is 2.1 to 2.6%. Figure 4.5
shows the relationship between the initial sludge concentration and the rate of the
concentration increase. It shows how poor the thickening efficiency is. At the
Toba Plant the efficiency is gradually lowering in recent years.
38
-------
Figure 4.5 Relationship between the Initial Sludge Concentration and
the Rate of the Concentration Increase
SJ
a
o
C
d
o
o
O
u
•
n \ (
o XT
o
DD\p A
A
1
n
*°
*\oR
V o
oc
\
A
^
:
•
X-
x
A \
•
0
0
Group
I
• Group n
A Group m
a Group IV
\
\
01234
Initial Sludge Concentration (%)
Table 4.3 Operation Data of Sludge Thickeners
1000
500
100
50
10
Gr.
I
n
III
IV
Total
Raw Sludge
Solids
t/d
35.6
39.7
35.4
25.6
136.3
Cone.
%
1.1
1.5
1.4
1.4
Thick Sludge
Solids
t/d
34.0
36.7
30.9
24.4
126.0
Cone.
%
2.6
2.5
2.1
2.1
Effluent
Solids
t/d
1.6
3.0
4.5
1.2
10.3
TS
mg/1
474
506
1,530
610
BOD
mg/1
185
152
579
176
Solids
Loading
kg/m2 -d
54.2
68.7
56.8
40.3
Overflow
Rate
m3/rn2-d
8.5
13.3
8.2
5.3
Detent.
Period
hrs.
8.9
7.3
9.8
15.0
4.3.3 DIGESTION TANKS
The digestion tanks are divided into four groups. Every one of those tanks is
equipped with a heating system and a gas agitator. The operation data of the
digestion tanks are shown by Table 4.4. It must be noted that the digestion
conditions of Group III tanks are different from the others, because in these
Group III tanks night soil is mixed with sewage sludge before digestion.
- 39 -
-------
At Group IV tanks the heating is done in the tanks with steam blowing,
while the tanks of the other Groups employ the heating by the duplex pipe
counter flow heat exchangers. The temperature in the tank is kept at 27 to 30°C.
The gas agitator is intermittently operated when sludge is fed in.
The digestion period is 23 to 30 days. The load of volatile solids is
controlled 1.1 to 1.6 kg/m3-d.
It is previously mentioned that the concentration of the sludge fed in is low.
The same of the digested sludge is also low being only 3.0 to 3.2%. The volatile
acids in the digested sludge at Groups I, II, and IV are 150 to 200 mg/1 and at
Group III it is 400 mg/1. The alkalinity in Groups I, II, and IV is 1,600 to 1,700
mg/1, while at Group III it is 3,800 mg/1. The BOD of the supernatant is 1,200 to
2,300 mg/1. In any of those tanks scum can hardly be found.
The digestion rate is low at every tank being approximately 30%. At these
tanks, altogether approximately 12.5 tons of volatile solids is decomposed, and
approximately 12,000 m3 of sludge gas is produced per day. After desulfurized,
approximately 4,500 m3 of the sludge gas is utilized for fuel for the digestion
tank heating, and other 7,500 m3 is used as supplementary fuel of sludge
incinerators.
Table 4.4 Operation Data of Sludge Digestion Tanks
Gr.\
I " 1
II
III
IV
Total
Feeding Sludge
Solids
t/d
7.6
15.4
16.9
6.5
17.3
63.7
Cone.
%
2.6
2.7
2.5
Volatile
Solids
%
65.2
70.5
65.9
Digested Sludge
Solids
t/d
4.5
9.5
10.1
6.4
30.5
Cone.
%
3.0
3.2
3.0
3.0
Volatile
Solids
%
58.3
57.4
59.3
57.4
pH
7.2
7.2
7.6
7.1
Alkali.
mg/1
1,649
1,706
3,828
1,604
Volatile
Acids
mg/1
196
149
396
165
Gr\
I
II
III
IV
Total
Supernatant
Solids
t/d
1.7
3.0
8.6
7.4
20.7
PH
7.3
7.3
7.7
7.3
TS
mg/1
6,338
5,347
1 1 ,249
10,588
BOD
mg/1
1,519
1,159
2,311
2,163
Digest.
Temper.
°C
26.8
27.7
28.8
30.0
Digest.
Period.
days
27
37
23
30
Volatile
Solids
Loading
kg/m3-d
1.5
1.2
1.1
1.6
Digest.
Rate
%
29
29
29
31
Gasif.
Solids
t/d
1.4
2.9
4.7
3.5
12.5
4.3.4 DEWATERING FACILITIES
For sludge dewatering, the vacuum filters of the belt type have been
employed. Eight filters of Group I dewater digested sludge and twelve filters of
- 40 -
-------
Group II dewater raw sludge. The operation data of those dewatering facilities are
shown by Table 4.5.
The concentration of the digested sludge to be dewatered is approximately
3%, while the same of raw sludge is approximately 2%. The alkalinity of the
digested sludge is 1,600 to 3,800 mg/1, while the same of the elutriated sludge is
approximately 600 mg/1. The elutriation of the digested sludge is done by two
stage counter flow elutriation tank. The alkalinity of raw sludge is 460 mg/1.
As coagulants, ferric chloride (FeQ3) and slaked lime (Ca(OH)2) have been
used. The chemical dosages to the sludge are 9.8% of FeCl3 and 46.5% of
Ca(OH)2 for Group I, and 4.9% of FeCl3 and 23.2% of Ca(OH)2 for Group II.
The filter yield rate is 5.3 kg/m2.hr at Group I and 12.3 kg/m2.hr at Group
II. The moisture content of the dewatered cakes is 77.1% at Group I and 72.5%
at Group II. At Group I the filter yield rate is low and the moisture content is
high. It is because the proper vacuum can not be retained owing to the following
two reasons. Firstly the concentration of sludge is low and hair cracks are caused
in the cakes on the filter medium at the time of dewatering due to the smallness
of the quantity of fibrous materials. Secondly the efficiency of the facilities has
been degraded due to superannuation.
The filter yield rate and the moisture content of the cakes are closely related
with the sludge concentration. The low concentration of the sludge has caused the
high dosage of the coagulants and the poor dewatering efficiency.
Table 4.5 Operation Data of Sludge Dewatering Facilities
Gr.
I
II
Total
Feeding Sludge
Solids
t/d
30.5
68.8
99.3
Cone.
%
3.1
2.2
Alkali.
mg/1
2,392
....
Elutr.
Sludge
PH
6.9
6.5
Alkali.
mg/1
607
461
Dewatered
Cakes
Qty
t/d
88.8
261.6
350.4
Solids.
t/d
12.9
56.8
69.7
Moist
Cont.%
77.1
72.5
FeCl3
%
9.8
4.9
Ca(OH)2
%
46.5
23.2
Filt.
Yield
Rate
kg/m2 -hr
5.3
12.3
4.3.5 INCINERATORS
All the dewatered cakes are incinerated. The incinerators are the
multiple-hearth type. Three of the six incinerators incinerate 60 tons per day
each, while the other three do 150 tons each.
The calorific value of dewatered cakes is 1,900 to 2,500 kcal/kg. As the
supplementary fuel, heavy oil and sludge gas are utilized. For prevention of air
pollution, low sulfureous heavy oil (sulfur content less than 0.8% and in winter
the same less than 0.5%) is used, and 35 to 40 liters of the oil is consumed per
ton of dewatered cakes. In case of digestion gas, whose calorific value is 5,600
kcal/m3, 50 to 70m3 of gas is consumed per ton of dewatered cakes.
The moisture content of the dewatered cakes is 72 to 77%. If the moisture
content is less than 75%, the incineration efficiency is satisfactory and the con-
sumption of supplementary fuel is comparatively small. If the moisture content is
over 75%, it is very hard to keep the incinerator at the proper temperature.
Especially the low temperature at the third and fourth stages, pre-heating stages,
causes imperfect combustion. Hence poor incineration efficiency.
- 41 -
-------
For the maintenance of incinerators, wear and corrosion of fans, rabble arms
and rabble teeth in the furnace and damage of bricks at the hearth have to be
checked from time to time.
4.4 SOME CONSIDERATIONS ON TOXIC SUBSTANCES AND HEAVY
METALS IN DISPOSING SLUDGE
As of 1975 approximately 400 tons of dewatered cakes is incinerated and 50
tons of ash has to be disposed of per day. As the sewerage system of the city is
to be expanded, a remarkable increase in quantity of sludge and ash is
anticipated. Consequently in the sludge incineration and ultimate disposal, we
have to use every discretion for behavior of the toxic substances and heavy metals
contained in the sludge and ash.
As shown by Table 4.6, the concentrations of toxic substances and heavy
metal in the inflowing sewage and the effluent are very low. However, they tend
to be adsorbed and concentrated in the sludge. Therefore, it has to be carefully
examined whether they pollute the air or not when incinerated and whether they
cause pollution of ground water or not after tne ash is used for landfill.
4.4.1 TOXIC SUBSTANCES IN THE EXHAUST GAS FROM INCINERATORS
AND THE COUNTERMEASURES
The concentrations of the toxic substances and heavy metals in the
dewatered cakes are not uniform. An example of analytical data is shown in Table
4.6. The concentration of iron is especially high, because ferric chloride is added
for the coagulation.
The exhaust gas from the incinerators is controlled by laws and regulations.
That is, the air pollution prevention law and the public nuisance prevention
regulation of Kyoto Prefecture regulate particulate matter and sulfur oxides. The
offensive odor prevention law restrains nasty smell, such as ammonia, hydrogen
sulfide, and trimethylamine.
The exhaust gas is treated by the scrubber of wet cyclone type. The analysis
table of the exhaust gas before and after the scrubber is Table 4.7. The
concentrations of the particulate matter, hydrogen sulfide and trimethylamine at
the outlet of the scrubber are within the standards.
No laws nor regulations control the toxicants and heavy metals from the
sludge incinerators. However, compared with the standards set for other
incinerators, some of the figures of the sludge incinerators are beyond the
standards. It means that the treatment by the single stage scrubber is not
satisfactory.
Therefore, remodeling of the incinerators is now being considered for the
perfect treatment of exhaust gas. According to the plan, a cooling tower with two
stage elutriation system, a tower for the elimination by means of sodium
haydroxide solution and ferrous sulfate solution, and an electric dust collector are
to be installed next to the existing scrubber so that particulate matter, sulfur
oxides, nasty smell, toxic substances, and heavy metals as well as white smoke
may be eliminated more effectively.
4.4.2 EFFLUENCE TEST OF TOXIC SUBSTANCES AND OTHERS FROM ASH
The concentrations of toxic materials and heavy metals in the ash are shown
42
-------
Table 4.6 Toxic Substances and Heavy Metals in Various Samples
(ppm)
Mercury
Cadmium
Lead
Organic
Phosphorus
Hexavalent
Chromium
Arsenic
Cyanide
Alkylmercury
Copper
Iron
Zinc
, Manganese
j Nickel
Chromium
Inflowing Sewage
Toba
Kjsshoin
0.0020 : 0.0017
0.000 i 0.000
0.00
0.00
0.00
0.001
0.06
0.0000
0.15
0.40
0.54
0.05
0.05
0.07
0.00
0.00
0.00
0.005
0.04
0.0000
0.23
0,34
0.42
0.09
0.03
0.06
Fushimi
0.0003
0.000
0.00
0.00
0.00
0.001.
0.00
0.0000
0.03
0.24
0.09
0.05
0.00
0.00
Effluent
Toba
0.0001
0.000
0.00
0.00
0.00
0.001
0.01
0.0000
0.01
0.03
0.07
0.04
0.01
0.01
Kisshoin
0.0003
0.000
0.00
0.00
0.00
0.002
0.02
0.0000
0.06
0.12
0.13
0.06
0.01
0.02
Fushimi
0.0001
0.000
0.00
0.00
0.00
0.001
0.01
0.0000
0.01
0.03
0.05
0.00
0.00
0.00
Dewalered Cake
Toba
5.25
4.72
105
0.00
9.73
0.51
956
46,800
1,850
486
138
497
Fushimi
2.22
1.82
160
0.00
10.10
0.15
250
24,500
780
152
48
65
Ash
0.077
3.7
20.4
14.4
0.72
897
52,600
2,921
1,035
250
548
Ash Solution*
Aver.
0.0000
0.000
0.04
0.00
0.05
0.011
0.01
0.03
1.11
0.09
0.01
0.0 1
0.45
Max.
0.0000
0.000
0.22
0.00
0.42
0.053
0.02
0.14,
6.05
0.80
0.03
0.05
1.90
Min.
0.0000
0.000
0.00
0.00
0.00
0.000
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Standards
(less than)
0.005
0.3
3
1
1.5
1.5
1
0.0005
• The sample is the 10% (w/v) ash solution filtered by Grade No. 5C filter paper ifter it had been constantly shaken for six hours.
Table 4.7 Analysis of Exhaust Gas
Particulate
Matter
Sulfur Oxides
Ammonia
Hydrogen
Sulfide
Trimethylamine
Methyl-
mercaptane
Methylsulfide
Mercury
Cadmium
Lead
Arsenic
Cyanide
Copper
Zinc
Nickel
Chromic Acid
Hydrogen
Chloride
Chlorine
g/Nm3
Nm3/hr
"
"
"
"
ppm
mg/m3
"
"
"
"
"
"
"
"
ppm
"
Inlet of
Scrubber
1.00
3.94
0.004>
0.155
0.0023
0.12
0.45
0.28
2.89
0.013
13.4
1.1
12.22
1.1
0.47
9.4
7.9
Outlet of
Scrubber
0.20
1.74
0.004>
0.137
0.0015
0.24
0.27
0.13
2.70
0.01 >
29.0
0.28
3.42
0.29
0.21
17.2
8.0
Standards
(less than)
0.7
6.54
134
2.685
0.671
0.3
0.5
40
0.3
3
0.3
20
3
Remarks
Air Poll, Prev. Law
Pub. Nuis. Prev. Reg.
of Kyoto Pref.
Offensive Odor
Prevention Law
Standards set by
Public Nuisance
Prevention Regulations
of Kyoto Pref. to be
applied Incinerators of
Wastes, such as Waste Oil
and Rubber.
43 -
-------
in Table 4.6. When the ash is used for landfill, a caution must be taken against
pollution of ground water by them. If the concentrations of a toxic substances in
the solution, which is made with the ash in accordance with the regulation,
exceed the standards, the sludge is adjudged toxic and has to be disposed of by
the method specially stipulated.
For the confirmation of freedom from toxicity, the solution of ash is
regularly tested. The results of recent ten tests are summarized in Table 4.6.
Only a few toxic substances have been found by the tests, but the
concentrations are much less than the stipulated standards.
Thus there is no problem of toxic substances. However, calcium and some
others are found in the ash solution as shown in Table 4.8 and the pH of the
solution is alkaline. Figure 4.6 shows the relationship between the pH in the
solution and the dilution ratio of the stipulated solution diluted with ground
water.
Table 4.8 Composition c f Ash Solution
pH
Total Solids
Total Hardness
Calcium Hardness
Magnesium Hardness
Chlorine Ion
Alkalinity
Silica
mg/1
-
„
,,
„
..
"
10.64
2,098
1,154
841
313
253.0
92.3
27.5
10.0
9.0
8.0
7.0
Figure 4.6 Changes of pH of Ash
Solution by Dilution
Note: Dilution Water:
Ground Water pH6.86
5 10
—S» Dilution Ratio (times)
15
- 44 -
-------
4.5 RESEARCHES ON SLUDGE ASH FOR ITS REUSE
It is expected that the quantity of sludge ash will rapidly increase from now
on. However, it is very hard to obtain the space for filling up. Therefore, it is
necessary to develop a new method to effectively reutilize the ash. Now
researches are under way on such matters as how to revivify the ash in nature,
how to use the ash as a material for road construction, how to use the ash to
make a lightweight aggregate, and others.
4.5.1 UTILIZATION FOR SOIL CONDITIONERS
Table 4.9 shows an example of the fertilizer components in the ash. The
slaked lime that is added as a coagulant at the dewatering process remains as
residue in the ash. Therefore, it can be used as a neutralizer of acid soil. Further
it can be used as a fertilizer because of the components shown in the Table 4.9.
Experimentally the ash is effective for the growth of root-crops. The growth of
aquatiic rice is also satisfactory if it is given appropriately. However, more careful
researches are required on the effect of the '.eavy metals contained in the ash
before it is widely used as fertilizer.
4.5.2 USE AS A MATERIAL FOR ROAD CONSTRUCTION
Experiments prove the possibility of using the ash as the material of
subgrade and subbase course of the road. In October 1973 when a road was
constructed in the Toba Plant, the ash was tentatively used as the material of the
subgrade. As for the quality the result seems satisfactory, though it is still being
carefully observed. To fill an excavated area in the Plant the ash was also used.
As shown by Table 4.10, the particles of the ash are very fine. Therefore,
when "it is used as a construction material, a caution must be exercised not to
scatter it.
Table 4.9
Fertilizer Com-
ponents of Ash
Table 4.10
Grain Size Dis-
tribution of Ash
Components
N
P20S
K20
Fe203
Si02
CaO
MgO
MnO
B202
0.10
4.00
0.35
11.39
29.91
34.22
2.55
0.14
0.05
Grain Size (mm)
4.76' 2
2 0.42
0.42 0.074
0.074 0.005
Less Than 0.005
2
18
27
48
5
45 -
-------
CHAPTER 5. SLUDGE PRODUCTION AND SOLID LOADING BALANCE
IN THE NISHIYAMA STP, NAGOYA
Outline of the Nishiyama STP 47
Equipment and Devices Installed . . . . 47
Primary Sludge Production 48
Sludge Production through the Actuated Sludge Process . . 49
Increase in Sludge Production by Chemical Addition .... . . ... 49
Summary and Future Tasks . . 49
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5. SLUDGE PRODUCTION AND SOLID LOADING BALANCE IN THE NISHI-
YAMA STP, NAGOYA
Methods for ultimate disposal and sites for disposal of sludge are limited in
Japan. Therefore, to obtain correct information on sludge production and its quality
in sewage treatment plants is of vital importance to setting up future measures for
treatment and disposal of sludge.
As people's life style, especially their dietary life, changes year by year, sludge
production is increasing in sewage treatment plants. Also, the quality of sludge is
expected to change: for example, its organic content will increase.
The purpose of the project is to obtain information on sludge production,
quality changes, kinetics of sludge production, etc. by means of a long-range
measurement at a typical treatment plant of domestic sewage which introduces the
activated sludge process. The Nishiyama STP in Nagoya has been selected and
surveys have been carried out jointly by the N:>goya City and the Public Works
Research Institute, Ministry of Construction. All data collected during two years of
surveys will be finally analyzed by a statistic measure.
Discussed in the following are equipment and devices installed in the Nishiyama
STP for these surveys and results of the survey of its beginning stage.
Outline of the Nishiyama STP
In the Nishiyama STP, sewage is collected by separate sewers, and biological
treatment by the conventional activated sludge process is conducted after the prima-
ry treatment. Population served is 46,000 and the average flow is 20,000 m3 /day
(5 mgd).
Raw sewage quality is as follows (daily average of the period from February to
June, 1975): BODs, 70 ~ 125 mg// (average 100 mg//) and SS, 60 ~ 230 mg//
(average 130mg//). Diurnal variation is large and thus STP is a typical treatment
plant for domestic sewage. Average loadings per capita base computed from average
influent polutant loadings, 46 g/person/day for BODs, 60 g/person/day for SS, 10.9
g/person/day for TN, and 1.52 g/person/day for T-P, all of which are average values
in Japan.
Fig. 5.1 shows the flow diagram of the STP. Its bays are separated into two,
to one of whose aeration tank alum is added now.
Sludge treatment is not carried out in the STP Produced sludge is stored in
holding tanks, then pumped to nearby sludge treatment plants periodically. Because
supernatant is not returned from sludge loading facilities, the STP is convenient to
obtain exact loading balance.
Equipment and devices installed
In this STP, withdrawal of sludge from the primary setter has been intermit-
tently performed 4 to 5 times/day and that of waste activated sludge, 1 to 2 times/
day, depending on its production.
Since it is difficult to measure manually all of the sludge, three electromagnetic
flow meters for measuring sludge flow rate and three ultrasonic solidmeters for
47
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measuring solid in the sludge have been installed. Fig. 5.1 shows their respective
locations. Of the three, one is for measuring sludge withdrawn from the primary
setter while the other two are for measuring waste activated sludge. Values measured
are transmitted to the control room and continuously recorded there. Fig. 5.2
shows installed meters. During four months until July, 1975, major troubles have
not occurred in connection with these meters.
Observations from the solidmeters remain stable for waste activated sludge con-
centration and the differences with observed values are within 10%. This may be
because in the case of waste activated sludge, fluctuations of concentration is small,
its quality is stable, and its withdrawal is conducted in a comparatively longer period
(about 30 minutes) with a pump. On the cont -ary, since sludge in the primary setter
is withdrawn in a shorter period (about 5 m mtes) by gravity and its concentration
changes greatly, it was difficult to get accural; results.
To know the potentials for sludge production, it is necessary to continuously
measure the water quality of influent and effluent of each facility. To measure the
concentration of suspended solids and organic matters continuously, turbidimeters
and TOC meters are scheduled to be install.
Because corelation between turbidity and SS has been found, measured turbidi-
ty is converted into SS values. As turbidimeters, the surface scatter type, and as TOC
meters, the type which continuous sample dose is possible, will be introduced. Fig.
5.1 shows locations of turbidimeters and TOC meters. As for TOC, it is planned to
measure samples from each location after dividing them into "total" and "soluble."
Primary sludge production
Table 5.1 shows the analytical values of the primary sludge. The percentage
of organic matters in sludge amounts to as high as 85%. The ratio of TKN and T-P in
the total solids was 1.7 to 3.7% and 0.3 to 0.7%, respectively.
Primary sludge production is the balance between solid amount in influent and
that in effluent. Until turbidimeters were installed, SS had been analyzed using com-
posite samples for 24 hours. Fig. 5.3 shows the relations between observed values
of solid quantity of influent and effluent and primary sludge withdrawn obtained
from values shown by flowmeters and solidmeters. Data are those from April to mid-
June. Figures in the upper column are the observed values of withdrawn amount and
those in the lower column are quantity of influent and effluent solids, the balance of
these two being estimated values of withdrawn amount.
As shown in the Figure, values measured by meters and those obtained from
the balances between influent and effluent quantity are not very well correspondent
with each other.
Reasons for this disagreement are not very clear but causes which can be con-
sidered are: (1) the composite sample used was not representative; (2) mistakes or
errors in calibrations of meters; and (3) analysis method of SS cannot represent the
total quantity of the primary sludge.
Table 5.2 shows the operational condition of the primary setter, and Table
5.3 shows average water quality.
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Sludge production through the activated sludge process
It has been pointed out that production of waste activated sludge is influenced
by a lot of factors. At this moment only a few data have been obtained, so discus-
sions on kinetics of production is not done here.
Fig. 5.4 shows reletions between waste activated sludge produced in the con-
ventional activated sludge process and solids in influent and effluent. The former
was obtained from flowmeters and solidmeters while the latter was gained from
composite samples for 24 hours, both manually. When MLSS in the aeration tank is
constant, the net sludge production is obtained by substructing influent solids from
the total of waste activated sludge and effluent solid.
During this period, average daily influent BODs loading was 680 kg/day,
average daily effluent BOD5 loading, 105 kg/day, and removed BODs loading,
575 kg/day. Other operational conditions are shown in Table 5.2 and 5.3.
Tranfer rates into sludge per day computed based on soluble BODs vary wide-
ly. After TOC meters are installed, studies on transfer rates based on TOC, in addi-
tion to BODs, and the production kinetics will be conducted using measurement
data covering a long period.
Increase in sludge production by chemical addition
Production of waste activated sludge at the bay where alum is dosed at the
extreme end of the aeration tank has been measured.
Alum is dosed so that Al/P may become 2 in the mole ratio. Ah (SO4 )s Hz O is
the ingredient of alum and the concentration of dose is 8 mg Al/P
Because the bay where alum is dosed and that where it is not dosed have the
same influent quantity, production of them have been compared on the basis of data
from May to June, 1975. The results are shown in Table 5.4.
The quantity of sludge at the bay with alum has increased more than that at
the bay without alum. The increase rate was nearly 40% for the former.
In the Table, the estimated values of the increase in terms of aluminum hydrox-
ide and aluminum phosphate are shown. From these values, it is known that the
quantity of alum dosage equals the increase in production of waste activated sludge.
Comparison between them are planned to be examined by changing the dose
rates of alum.
Summary and future tasks
The outline of the project at the Nishiyama STP to make a survey on sludge
production from sewage treatment plants started in February, 1975 has been
described in the above. Because this project is still at its initial stage, sufficient infor-
mation has not been obtained yet. It is expected, however, that the results to be
gained from this project will give data useful to sludge treatment and disposal plans
at sewage treatment plants to be built in the future.
Future tasks of the survey of the project will be as follows:
1) By observation of sludge production for a long period of time, to clarify sea-
sonal fluctuations of its quantity and quality, yearly changes, etc.
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2) To install turbidimeters and TOC meter and to clarify effects of concentration
of suspended solids in sewage on sludge quantity and the kinetics of transfer
into sludge in the process of biological process of organic matters.
3) To clarify material loading balance in sewage treatment plants.
4) To study a long-range view for methods of sludge treatment and disposal at
sewage treatment plants, mainly on the treatment of domestic sewage.
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Table 5.1 Primary Sludge Characteristics
^\^ Item
Sample ^\^
1
2
3
V.S content
(%)
83.4
85.7
84.7
TKN content
TS base (%)
1.2
3.1
1.4
VS base (%)
1.5
3.7
1.7
T-P content
TS base (%)
0.3
0.7
0.7
VS base (%)
0.4
0.8
0.4
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Table 5.2 Operational Conditions of the Plant
on
Average
daily flow
(m3/d)
21,300
Primary settler
Detention
time
Or)
1.8
Overflow
rate
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Table 5.3 Waste Water Characteristics
(mg/£)
^\Category
Item ^\^
Turbidity
S.S
BOD5
TOC
T-P
TKN
Raw sewage
Ave.
80
118
99
80
3.54
25.2
Range
56 -132
81 -162
69 -124
51 -122
2.59- 4.92
21.8 - 29.1
Primary eff.
Ave.
52
41
64
59
3.45
25.8
Range
32 -92
31 -78
47 -95
38 -87
2.01- 4.40
20.6 -39.1
Final eff.
Ave.
6.7
6
9.5
19.3
1.25
13.1
Range
4.1 -11.3
2 -11
6.5 -16.5
8.3 -14.5
0.59- 1.97
9.9 -21.0
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Table 5.4 Comparison of Sludge Production
Sludges
Waste activated suldge
kg/d
(rng/2)**
Solid in effluent
kg/d
(mg/£)**
Total
kg/d
(mg/2)**
Addition as A1(OH)3 *
kg/d
(mg/C)**
Addition as A1P04 *
kg/d
(mg/C)**
Control
536
(45.4)
77
( 6.5)
613
(45.4)
-
-
-
-
Alum addition
545
(46.1)
310
(26.2)
856
(72.5)
184
(15.6)
139
(11.8)
* Calculated value. ** Based on inflow.
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ITM)
,X
Grit
Chamber
viuu
1
1
1 _
Preaeration
Tank
SM ) Solid Meter
FMI Flow Meter
.TOCI TOC Meter
(TM) Turbidity Meter
V -S
»- To the Adjacent STP
Sewage
— Sludge
Fig. 5.1 Flow Diagram of Nishiyama STP
-------
ILLUSTRATION NOT AVAILABLE
Fig. 5.2 Installed Flow Meter and Solid Meter
(Waste Activated Sludge Pipe)
56
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Cn
--0
Solid Withdrawn
D
Influent Solid
I••:•:I Effluent Solid
10
15
April
20
25 20
25
30 1
Calendar Date May
Fig. 5.3 Solid Loading Balance Over Primary Settler
June
10
-------
c_n
oo
700 -J
600 H
500 A
J
a 400
1
o
_J
300 J
200 -J
100 -\
Influent Solid
Effluent Solid
Waste Activated Sludge
20 21 22 23 24 25 26 27 28 29 30 31 1 2 3 4 5 6 7
May Calendar Date June
Fig. 5.4 Solid Loading Balance Over Activated Sludge Process
9 10
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Fourth US/JAPAN Conference
on
Sewage Treatment Technology
Paper No. 2
AUTOMATION AND INSTRUMENTATION FOR
WASTEWATER TREATMENT PLANT
October 24, 1975
Cincinnati, Ohio
Ministry of Construction
Japanese Government
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AUTOMATION AND INSTRUMENTATION FOR
WASTEWATER TREATMENT PLANT
1. Basic Conception of Automation and Instrumentation in Sewage
Treatment Plant .... 61
A. Sugiki, Japan Sewage Works Agency
2. Automatic Water Quality Measurement for Wastewater Treatment '2
K. Murakami, PWRI, Ministry of Construction
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CHAPTER 1 BASIC CONCEPTION OF AUTOMATION AND
INSTRUMENTATION IN SEWAGE TREATMENT
PLANTS
1.1 Introduction 62
1.2 Some Points to be Solved in Automatic Control 62
1.3 Basic Conception for Automatic Control 63
1.4 Profile of Automatic Control Systems 64
/- rj
1.5 Future Research ....
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1.1 INTRODUCTION
Several different characteristics exist in the waste water treatment process as
compared to such process at an ordinary manufacturing process. These particularities
are necessary to be taken into consideration when the instrumentation and the auto-
mation are introduced into a sewage treatment plant. For instance:
(a) Both quantity and quality of sewage flow vary to a great extent regardless of
the optimum conditions of a sewage treatment processes. Accordingly, it is of
necessity to forecast and preestimate it to some extent for operation as opti-
mum.
(b) Since a sewage treatment plant concerns itself widely in the public interests and
the effluent therefrom has a great impact to the environment, it is needed al-
ways to secure stable and best water quality of effluent. Minimum required con-
ditions, of course, should be maintained even in an emergency.
(c) Time required for through whole treatment process after arriving at a treatment
plant ranges from a few hours to 10 hours. In other words, the time constant is
considerable long.
Therefore, in order to increase the treatment efficiency the feed forward con-
trol is requisite.
(d) Although mechanical and physical treatment process such as screening and sedi-
mentation are included in the waste water treatment process, biological treat-
ment plays a main role for waste water treatment in Japan. Hence a control
system should be built up for the most suitable environment to microorganism.
As the sewage treatment plant becomes larger, process has rather long time
constant and combination of complicated many different systems, so it is very dif-
ficult to operate it properly. To cope with this complexity it has been necessitated
to introduce the technique of electronic instrumentation as to systematic control on
the process.
Types of instrumentation and control devices range from a analog controller to
a large-scale digital computer, and all are being in wide use according to the purpose
of control and the scale of treatment plants. As to introducing a computer although
there are arguments the general trend goes to the introduction of computer. The case
of waterworks which is rather ahead in the instrumentation and the automation of
water purification plants gives a good example. At the present, the use of computer
is limited to a role of an information center: such as data collection, indication, re-
cording, supervision, data storage and calculation. However, with the further pro-
gress of studies on the mode of biological treatment process and development of
software, various types of feed forward control, adaptive control or optimizing
control will be made available, and the function of computer control may be far be
improved.
1.2 SOME POINTS TO BE SOLVED IN AUTOMATIC CONTROL
If the technique of automatic control is introduced into the operation and
maintenance of a sewage treatment plant, it will become possible to control more
effectively for treatment process under the characteristics of the sewage treatment
-------
mentioned above, and at the same time the reduction of personnel expenses and
further more than cutback of treatment cost and also the improvement of working
conditions of the staff to be engaged in as well as the labor and skill saving are ex-
pected. However, the relation between the effects or benefits of the automatic
control and the costs required for it, that is to say, the cost performance, would be
variable according to the scale of treatment plants and/or the respective local condi-
tions such as fluctuation of water quantity and quality. There are some technical and
operational problems left to the future to need technological development as follows.
(a) Highly dependable various automatic measuring devices and instruments are
required for the automatic control. Many of the quantitative measuring instru-
ment such as a flow measuring devices and a water level meter are available
now, except some modification in needed some cases. On the contrary, the
insufficient performance of reliability, responsibility, stability and repeatability
etc. particularly of detectors (sensors) of the qualitative measuring instrument
such as a suspended solid or an organic substance, BOD, COD, TOC etc., has
been pointed out.
(b) Operation and maintenance of treatment plant usually depend on the experi-
ence and intuition of skilled employees. When the automatic control is put into
practice, it becomes necessary to select suitable operational indices for this kind
control. We need kinetic model of treatment process, and now strongly con-
ducted studies but unfortunatedly not yet the models are determined. Further
development of measuring apparatus as well as kinetic models of treatment
process would be expected.
(c) With the implementation of the automatic control, manner of operation and
maintenance are conducted in different ways. Therefore, it is highly necessary
to establish a system of education and training for the staffs in charge so that
they may fully understand the system composition and how it works and may
perform a proper operation and they may take necessary action promptly and
correctly to cope with abnormal condition in emergency.
1.3 BASIC CONCEPTION FOR AUTOMATIC CONTROL
The basic conception for the water treatment system was formulated as follows
after having been taken into consideration the previously-mentioned characteristics
of the process at this time.
(a) Since the studies of process kinetics and the development of respective water
quality sensors and still incomplete at the moment, it is appropriate to lay more
emphasis on the quantitative control. These points, however, seem to be de-
veloped step by step with time. After evaluation on new developments, new
techniques are introduced for the qualitative control time to time.
(b) Although sewage treatment plants are mostly planned to complete with in next
20 years, a stage construction method is usually applied. Therefore, the auto-
matic control should be so designed as to function at every stage respectively.
For the treatment plant, of which designed capacity exceeds 100,000 cubic
meter employed, a computer should be introduced.
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(c) The quantitative control plays a main part presently, but as treatment plant
become larger in scale, items of supervision and data to be handled increases so
much that the operation under man power may exceed his ability. Hence, a
computer should be introduced to ensure the more effective and more detailed
automatic supervision on various apparatus in plant to keep operation record
and process control. In this case, back up system should be prepared in order
to secure to keep good operation in case of emergency.
(d) Pumping stations for sanitary sewage and storm sewage need to be so designed
that they will be operated automatically according to the scale, rather small and
at the same time, it is necessary to ensure the remote supervision and control
from a treatment plant or the nearest pumping station.
(e) In future, it is required to measure rainfall precipitation, water level, amount of
flow and water quality, etc. at the desired points in the catchment area and to
transmit to a central control office through telemeter devices so as to enable
more reliable rational operation to control stormwater.
(f) Even though a treatment plant is planned with quantitative automatic control,
the necessary incidental facilities are needed at the planning stage so that the
qualitative automatic control will be possible in future.
1.4 PROFILE OF AUTOMATIC CONTROL SYSTEMS
Sewage treatment process consists of pumping station, preliminary sedimenta-
tion tank and chlorination tank all working as one system.
Explanation will be made below as to the forms and methods of control, while
referring to those machinery, instruments and devices that are included in the con-
trolled system by each establishment. It is briefly described on the control system in
each process.
(a) Pumping station
Pumping stations are cassified into booster pumping station and those in the
treatment plants, and also collecting sewage system differ from the separate
system to the combined one. Fundamentally for all the types control systems
of pumping station are about same one with little alternation by the case. Ap-
paratus such as inlet gate, screening, grit chamber, sanitary sewage pump and
storm sewage pump are to be controlled in a pumping station. Inlet gates are
manipulated so as to control incoming sewage to treatment plants. Operation
of the gate are controlled by sign of the unusual rise of water level at an inlet
or at a wet wall. Usually, when water level goes over the height already set up,
the gate will be closed automatically with a use of analog regulators, etc., and
the manipulation to open it is performed at on site or through the remote
manual operation if possible, which needs such as reservoir pond. Of course,
in case the incoming flow rate is desired to be controlled for the better per-
formance of treatment, it should be designed to make possible the closing gate
through the remote manual operation. The control in this case will be needed
such devices that the sequence control device coupled with the measuring ap-
paratus are to be required. In future, if incoming How rate of sewage can be
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forecast with a use of rainfall precipitation data in a catchment area and so on,
or the forecast of the quality of incoming water will be made available with a
use of monitoring apparatus of water qualities, the feed forwared control and
adaptive control become applicable with the additional introduce of the pro-
cesser control apparatus.
If there are installed grit chamber, the adaptive control and the optimizing
control should be applied thereto with the surface loading or the velocity of
flow in the chamber being constant rate. In the control with a constant rate of
surface loading, an inlet gate is manipulated after selecting the number of cham-
ber according to the incoming flow rate of water. The control with a constant
velocity of flow in the chamber is performed by manipulation an inlet gate and
an outlet gate after selecting the number of basin according to the incoming
flow rate and the water depth of the chamber. In this case, the sequence control
device, the measuring apparatus and the process control apparatus are necessary
and the control is conducted by sequential computer control method. As for
grit chamber, the programmed and the conditional control are both used joint-
ly, and in the former the time scheduled operation is performed with a use of
incoming flow pattern, while in the latter it works only when a difference in
water level before and behind a screen exceed a fixed difference. A screen
scraper and lifting machine and a belt conveyer are naturally in combinated,
and the control appratus are the sequence control device and the measuring
appratus. Further, a control based on the forecast of the volume of screenings
produced will be installed in future. Since it seems possible to presume the
volume of screenings produced on the total volume of incoming flow, the pro-
cesser control appratus is necessary to be set up so that equipment of screen,
i.e. rake scrapers may start working when the total volume reaches a fixed
amount.
In respect of grit removal facility, the control method is also the same as that
of a screening devices. The programmed control, under which the time sched-
uled operation is performed with a use of incoming flow pattern, is applied to
start working machine at the condition which the facility starts working when
the volume of grit deposit reaches a fixed height.
Automatically-operated sanitary sewage and storm sewage pumps are to be
under the level control (conditional control), and thereby they start working
when the water level at wet well (in the case of a storm sewage pump, the water
level reaches a fixed level which pump should be started) reaches the upper
limit of a fixed point and stop when reaching the lower limit.
In the case of a sanitary sewage pump the level control depending on the water
level at a wet well for rather unusual condition, flow control are needed so that
inflow and outflow are regulated to maintain as to the certain flow velocity in
grit chamber as possible. The outflow rate will be controlled through the selec-
tion of the number of pump, the number of revolution and the opening of
control valve, and the sequence control device and the measuring apparatus for
are required for this purpose. If the optimum control of outflow rate is planned
in future, the processer control apparatos will become essential.
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A storm sewage pump is controlled depending on the condition based on the
water level at wet well or at the point where effluent discharge. In future, if the
time comes when the inflow pattern, the detention time of sanitary sewer, etc.
can be forecast through the rainfall, or when the necessary data for estimate
incoming flow rate of sewage can be transmitted from a booster pumping sta-
tion and/or the desired points along a force main just like in the case of a storm
sewage pumping station in the treatment plant, the feed forward control will be
made available by adding the processer control apparatus.
(b) Primary sedimentation tank
Such appratarus as sludge pump, a withdrawal valve and a scum collecting
device are to be controlled by instrumentation. A sludge pump and a with-
drawal valve start working by signal of timer and stop when sludge density
lowers down to desired concentration or when the sludge volume withdrawal
reaches are fixed volume. In future, it is necessary to combine the level control
under which they start working when the measured volume of sludge deposit
reaches the upper limit of a certain height and stop when sludge height reaches
the lower limit.
A scum collecting device is switched on and off intermittently at on site or
through the remote manual-operation, aside from being controlled by signal of
timer. In future, the feed forward control is to be introduced depending on
pattern of scum volume produced which is forecast by incoming flow rate,
water quality. Accordingly, the processor control apparatus will be needed in
future in addition to the sequence control device and the measuring apparatus.
(c) Aeration tank
Appratus that are the controlled system of an aeration tank include a blower, a
suction valve for air supply, and a return sludge pump. A blower and a suction
valve are to supply an adequate volume of air for the microbic reaction in an
aeration tank. There are two kinds of control systems on dissolved oxygen in
aeration tank. One is the proportional control of incoming flow rate of sewage
and the other is to keep constant dissolved oxygen concentration in the tank.
The former is the control in supplying the air in proportion to the incoming
flow rate of sewage, whereas the latter is to control the air by signal from a dis-
solved oxygen meter so as to maintain the dissolved oxygen concentration in an
aeration tank at a fixed concentration. The air supplied is adjusted by the num-
ber of blower and the opening of suction valve. In future, the optimum control
is to be employed which are depending on the estimation of the required vol-
ume of air from the incoming flow rate and water qualities (BOD, COD, TOC
etc.) as well as of signal from a dissolved oxygen meter in aeration tank. In the
case of a return sludge pump, the number of pump and the number of revolu-
tion are controllable, based on the required volume of return sludge. As for the
switchover of the number of pump, a starting order would be arranged so as to
the same running period of respective pumps. Its control method include the
proportional control of the incoming flow rate and the MLSS at the constant
concentration based on the density of return sludge. In this cases, it is necessary
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to equip the sludge holding tank for preperly return sludge. In future, the
optimizing control should be performed in consideration of the biological acti-
vate of return sludge as well as the BOD load (f/M) after measuring the BOD
(COD, TOC) in the raw sewage.
(d) Final sedimentation tank
In the final sedimentation tank a excess sludge withdrawal pump which starts
working under signal of a timer and stops when the sludge density lowers down
to a fixed concentration, or when the top of sludge zone reaches down to a
fixed height. The timer is being set itself upon the programmed control utilizing
a pattern of incoming sewage. In future, the level control will be put to use
under which a excess sludge withdrawal pump starts working when the height
of sludge deposit reaches the upper limit of a fixed height and stops upon its
down to the lower limit. Further, it is to focus the optimizing control of sludge
distribution of tanks by estimation of sludge produced from the quality of raw
sewage for example the BOD or COD, TOC.
(e) Chlorination facility
There is some difficult situation whether chlorination of sewage effluent is ef-
fective means or not especially regards to downstream water supply system. At
present time, chlorination is required to sewage effluent if coliform counts in
the effluent exceeds 3000/ml. Next action not yet determined in relation to
chlorination, but some alternation will be expected.
Chlorination is applied in proportion to the flow rate of effluent, but its con-
centration of chlorination in effluent would be determined measuring the
concentration of residual chlorine and the counts of coliforms.
In future, as the optimum control of chlorination would be such manner as
injected after measuring automatically the residual chlorine, then the processer
control apparatus is to be required in addition to the sequence control device
and the measuring and operational apparatus.
A detoxitation devices are required for emergency emission of chlorine gas in
chlorination chamber. An aspiration blower of the escaping gas and an injeca-
tion pump of the dechlorination agent such as sodium thiosulfate start working
by signal from detector for chlorine gas. The manipulation to stop of dechlori-
nation devices should be done at the machine side for the sake of safety.
1.5 FUTURE RESEARCH
The problems on the development of automatic control of treatment plant
operation were pointed out, and the best practical system at present was proposed.
Also target system in future is shown, but joint efforts of government people
and manufacturers is inevitable for the application.
Study report about automatic control development has been presented since
1960 in Japan and even simulation model study by computer is published now.
Since 1974 development study by a manufacturer granted from Ministry of
Construction and same study by Japan Sewage Works Agency started from investiga-
tion of many types of sensor and process kinetics Analysis.
The abstract of our study objects is as follows.
67 -
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(a) We are going to do systematic investigation of durability, operational difficulty
and accuracy of measuring equipment and make the questions clear.
(b) We are going to design and construct treatment plant which adops best applica-
ble full automatic controll system proposed by us. Then the cost-effectiveness
performance will be cleared.
(c) We are continueing the kinetics study of actual plant operation. And using
30 m3/day pilot plant which will be complete by 1976, simulation experiment
is going to be done under various operation conditions to aim quality control
application in future.
68 -
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Items To Be Measured Manually at a Final Sedimentation Basin
(1) Cadmium and its chemical compound;
(2) Cyanide;
(3) Organic phosphate compound;
(4) Lead and its chemical compound;
(5) Sexivalent chrome compound;
(6) Arsenic and its chemical compound;
(7) Mercury, alkyl mercury and other mercuric compound;
(8) BOD (Biochemical Oxygen Demand);
(9) COD (Chemical Oxygen Demand);
(10) SS (Suspended Solid);
(11) Transparency.
69 -
-------
A DRAFT OF AUTOMATIC CONTROL AT SEWAGE TREATMENT PLANTS
AT THE PRESENT HME
\Vaier
Treatment
Facilities
Pumping
Station
Preliminary
Sedimentation
Tank
Aeration
Tank
Final
Sedimentation
Tank
Chlonnalion
Facility
Control Device
Controlled System
Inlet Gate
Screenings Facility
Sand Removing
Facility
Sanitary Sewage
and Storm
Sewage Pumps
Raw Sludge Pump
Pulling-out Valve
Scum Removing
Device
Blower
Return Sludge
Pump
Surplus Sludge
Pump
Chlortnation
Device
Neutralization
Device
Control Form
Open Loop
Control
- ditto -
- ditto -
Closed Loop
Control.
Open Loop
Control
Open Loop
Control
- ditto -
Open Loop
Control,
Closed Loop
Control
Open Loop
Control,
Closed Loop
Control
Open Loop
Control
Closed Loop
Control
Open Loop
Control
Control Method
Conditional Control
(Remote Hand-
operation)
Conditional Control
Programed Control
- ditto -
Level Control
Discharge Control
Conditional Control
Feed Forward
Control
Conditional Control
Programed Control
Conditional Control
Conditional Control
DO Uniform Control
Proportional Control
of Inflowing Volume
of Water
Conditional Control
MLSS Uniform
Control
Proportional Control
of Inflowing Volume
of Water
Conditional Control
Programed Control
Processer Control
Uniform Control
Conditional Control
Constituent Apparatus
Sequence Control
Device
Processer Control
Apparatus
Measuring Control
Apparatus
Sequence Control
Device
Measuring Control
Device
Sequence Control
Device
Sequence Control
Device
Measuring Control
Apparatus
Processer Control
Apparatus
Sequence Control
Device
Measuring Control
Apparatus
- ditto -
- ditto -
- ditto -
Sequence Control
Device
Measuring Control
Apparatus
Processer Control
Apparatus
Sequence Control
Device
Measuring Control
Apparatus
Processei Control
Apparatus
- ditto -
Back-up
Use What is
One Rank
Below the
Control Method
- ditto -
- ditto -
- ditto -
- ditto -
- ditto -
- ditto -
- ditto -
- ditto -
- ditto -
- ditto -
Items to be
Supervised
(Automatically)
Water Level at
Pump Well
Water Level at
Inflowing
conduit
Water Level
Before and
Behind Screen
(Volume of Sand
Deposit)
Water Level at
Pump Well
Inflow Rate PH
Volume of Raw
Sludge Pulled out
Density of Raw
Sludge (Volume
of Sludge
Deposit)
Volume of
Wind Sent
MLDO (MLSS)
Return Sludge
Rate
Density of
Return Sludge
Volume of
excess Sludge
Density of
excess Sludge
(Volume of
Sludge Deposit)
Volume of
Water
Discharged
Chlorine dosing
rate
Concentration of
Escaping
Chlorine
Hems for
Manual
Measurement
Volume of
Screenings
Volume of
Sand Removed
SV
Residual
chlorine
Concentration
(as per
attached sheet)
MPN
Items for
Data Process
Rainfall
Precipitation.
Water Level,
inflow rate PH
(Volume of
screenings.
Volume of
Sand Removed)
Volume of
Sand Deposit
Volume of Raw
Sludge withdrawn
Density of Raw
Sludge
Volume of
Sludge Deposit
MLDO, MLSS
(SV)
Volume of
Return Sludge
Density of
Return Sludge
Volume of
excess Sludge
Density of
excess Sludge
Volume of
excess Deposit
Volume of
Water Discharged
Chlorine
dosing rate
residual Chlorine,
MPN
Concentration of
Escaping Chlorine
Remarks
Data Processing Device:
Small-scale (Punching Recorder and
Integrating Meter)
Medium- and Large-scale
(Daily Report, Monthly
Report, Trouble and
Running Record using
an electronic computer)
Central Monitory Facility:
Monitoring, Operate
ITV (Sand Basin, Discharging
Outlet and other facilities
inside a plant to be
monitored)
Note: A storage tank for return
sludge is required.
Items in the parenthesis
are to be measured,
but not to be used
for the control
parenthesis
is to be fLUed
manually
-------
IN THE FUTURE
Water
Facilities
Pumping
Station
and Storm
Sewage Pumps
Preliminary
Sedimentation
Tank
Aeration
Tank
Final
Tank
Chlorination
Facility
Control Device
Controlled System
Inlet Gate
Screenings Facility
Sand Removing
Facility
Sanitary Sewage
and Storm
Sewage Pumps
Raw Sludge
Pump Outlet
Valve
Scum Removing
Device
Blower
Return Sludge
Purnp
Excess Sludge
Pump
Chlorination
Device
Neutralization
Device
Control Form
Open Loop
Control
- ditto -
- ditto -
Open Loop
Control,
Closed Loop
Control
Open Loop
Control
- ditto -
Open Loop
Control,
Closed Loop
Control
- ditto -
Open Loop
Control
Closed Loop
Control
Open Loop
Control
Control Method
Conditional Control
Remote Hand-
operation
Conditional Control
Programed Control
- ditlo -
Conditional Control,
Level Control
Inflowing Volume of
Water Control
Feed Forward
Control
Conditional Control
Programed Control
Conditional Control
Conditional Control
Ratio Control of
Ail Volume
Cascade Control
Optimizing Control
Conditional Control,
Optimizing Control,
Programed Control
Cascade Control
Uniform and Ratio
Control of Return
Sludge Volume
Conditional Control
Programed Control
Processes Control
Uniform Control of
Injected Volume
Ratio Control of
Injected Volume
Conditional
Control
Constituent Apparatus
Sequence Control
Device
Measuring Control
Apparatus
Processes Control
Apparatus
- ditto -
- ditlo -
- ditto -
- ditto -
- ditto -
-ditto -
- ditto -
- ditto -
-ditto -
Sequence Control
Device
Measuring Control
Apparatus
Back-up
Use What Is One
Rank Below The
Control Method
- ditto -
- ditto -
- ditto -
- ditto -
- ditto -
- ditto -
- ditto -
- ditto -
- ditto -
- ditto -
Items to be
Monitored
(Automatically)
Water Level at
Pump Well
Water Level at
inflowing
conduit
Water Level
Before and
Behind Screen
Volume of
Sand Deposit
Water Level at
Pump Well
Inflow rate
PH
Volume of Raw
Sludge Pulled
Volume of
Sludge Deposit
Density of
Sludge
airflow rate
MLDO
MLSS, SV
Volume of
Return Sludge
Density of
Return Sludge
TOC(orTOD)
Volume of
excess Sludge
Density of
excess Sludge
Volume of
Sludge Deposit
Rate of Water
Discharged
Chlorine dosing
rate
Residual Chlorine
Concentration
of Escaping
Chlorine
Items for
Manual
Measurement
Volume of
screenings
Volume of
Sand Removed
(as per
attached sheet)
MPN
Items for
Data Process
Rainfall
Precipitation,
Water Level,
inflow rate
PH
Volume of
Sand Deposit
(Volume of
screenings,
Volume of
Sand Removed)
Volume of
Raw Sladge
Pulled out
Volume of
Sludge Deposit
Density of
Sludge
air flow rate
MLDO, MLSS,
SV
Volume of
Return Sludge
Density of
Return Sludge
TOC (or TOD)
Volume of
excess Sludge
Density of
excess Sludge
Volume of -
Sludge Deposit
Volume of
Water Discharged
Chlorine dosing
rate
Residual Chlorine
of Escaping
Chlorine
Remarks
Data processing device is for daily
report, monthly report, trouble and
running record through jn electronic
computer.
Central Monitory Facility:
Monitoring, Operate
ITV (Sand Basin, Discharging
Outlet and other facilities
inside a plant to be
monitored)
Note- a storage tank of return sludge
is required.
Items in the
parenthesis is to be
filled manually
-------
CHAPTER 2. AUTOMATIC WATER QUALITY MEASUREMENT FOR
WASTEWATER TREATMENT
2.1 Introduction . 73
2.2 Automatic Water Quality Monitoring of Raw Sewage 73
2.2.1 Development of Automatic Cyanide Monitor 73
2.2.2 Automatic Measurement of TOC 75
2.2.3 Automatic Detection of Surface Oil ' *>
2.3 Automatic Measurement of Water Quality for Process Control of the
Secondary Treatment . . . . 75
2.4 Automatic Measurement of Water Quality for Process Control of the
Tertiary Treatment . 76
2.4.1 Measurement of Nutrients such as Ammonia Nitrogen by Automated
Colorimetric Analysis .... 76
2.4.2 Automatic Measurement of Ammonia and Nitrate by Electrodes ... 76
2.4.3 Use of Turbidimeters 77
2.4.4 Others 77
2.5 Future Aspect of Study . 78
72 -
-------
2. AUTOMATIC WATER QUALITY MEASUREMENT FOR WASTEWATER
TREATMENT
2.1 INTRODUCTION
In the field of wastewater treatment, measurement of water quality is necessary
for a variety of purposes, such as water quality monitoring of industrial wastes
discharged into the sewerage system, water quality monitoring of influent to sewage
treatment plants, process control of the secondary and tertiary (advanced)
treatment, and water quality monitoring of effluent from sewage treatment plants.
Virtually all of these measurements are now performed by manual sampling and
analysis. In many cases, however, automatic continuous measurement is needed.
Water quality parameters for which continuous measurement can be now used are
very limited except in the case of comparatively clean treated water. Water
temperature, pH, oxydation-reduction potential, dissolved oxygen and sludge
density, are parameters which can be measured without much trouble. Even in
measuring these parameters, considerable maintenance and inspection are required.
Major points that need a special consideration in the development of automatic
continuous measurement of sewage quality are as follows:
(a) Growth of slime
Because sewage normally contains a lot of organic matters and is suitable for
propagation of microorganisms, biological slime tends to grow inside the piping or
other portions of the equipment contacting sample water. Slime not only causes
clogging but interferes measurement.
(b) Effects of suspended solids
When measuring water quality of raw sewage containing high suspended solids,
consideration much be given to minimize clogging at sampling portion or inside the
piping. The use of automated colorimetric analysis is difficult when the level of
suspended solids is high.
(c) Existence of interferences
Generally speaking, the composition of sewage is more complex than those of
river water or industrial wastewater and therefore masking of interferences is more
critical.
Thus automatic continuous measurement of sewage water quality is more
difficult than that of river water, etc. But as its necessity is very high, efforts are
made to develop and put into use devices for this purpose.
2.2 AUTOMATIC WATER QUALITY MONITORING OF RAW SEWAGE
2.2.1 DEVELOPMENT OF AUTOMATIC CYANIDE MONITOR
Cyanide is one of the toxic substances which may be discharged into the
sewerage system. By controlling its discharge, reduction of discharge of heavy metals
from industries such as plating works can be attained. Therefore, the Ministry of
Construction gives the first priority to the development of automatic cyanide
monitoring device.
The Ministry has been supporting studies on developing automatic free cyanide
monitoring device including field tests using model devices during the past two
- 73
-------
years. In measuring cyanide by selective-ion electrodes, it is the most important to
prevent the effects of interferences. Sulphide, iodide, bromide, sulphite, thio-
sulphite, thiocyanate and organic substances with SH-radical are the major
interferences which may be present in sewage. However, in the case of normal
sewage, only sulphide will bequire consideration. Fig. 2.1 shows the degree of
interferences of anions other than sulphides. Sulphides were removed first from
samples by addition of cadmium nitrate. And then, each sample was devided into
two parts. One part of the sample was then anion exchanged. The same amounts of
cyanide were added to both parts of the sample, and the concentrations of cyanide
were measured by an ion electrode. The figure shows that measurement of raw
sewage is possible when masking of sulphide is performed. In the case of primary
effluent of night soil treatment plants, interferences of anions other than sulphides
are perceived. Most of these are considered to be organic substances with SH-radical,
such as thioglycollic acid. For the masking of sulphides, cadmium, bismuth, zinc and
lead are effective. Above all, the most stable masking is possible by adding cadmium,
so cadmium mitrate has been used in field tests. But because adding these heavy
metals to sewage even in a small quantity is not desirable, other methods of masking
are being studied, such as one using filter paper on which cadmium is coated by
vacuum evapolation or one utilizing other masking agants than these heavy metals.
In the former method, cadmium can be recovered easily but the amount of sulphur
to be removed is limited and is not suitable for sewage containing a large quantity of
sulphides. As masking agents other than heavy metals, it has been found that sodium
nitroprusside and several types of nonionic and anionic polymers (if added in a high
concentration) are effective, but they are also toxic. Thus, studies must be
continued to find more proper masking methods of sulphides. For masking of
organic substances with SH-radical, it has been proved that sodium molybdate is
effective.
Fig. 2.2 shows the block diagram of model device. In the early stage of field
tests at the Kisshoin Sewage Treatment Plant, Kyoto, several points to be improved
were discovered. Most essential of them was the phenomenon that the surface of the
sensing element of the cyanide electrode was deteriarated even if masking of
sulphides had been carried put. To cope with this, the electrode was modified as
shown in Fig. 2.3 so that mechanical scraping can be performed continuously.
After the above modification, test runs have been continued over one year until
today during which maintenance work such as calibration has been done every two
weeks. Table 2.1 shows causes by which data could not be obtained during 1974 and
the ratios of the periods during which data were lost to the total period of
operation. The period during which data could not be obtained is about 37% of the
total period. This is not very small percentage but most of the causes can be
eliminated by more frequent inspection and maintenance work and it is not very
difficult to reduce the percentage to less than 10%.
Though there remain some problems with masking agents, we could develop a
usuable equipment for automatic free cyanide measurement. However, as pretreat-
ment standards provide for regulations for total cyanides including complex
cyanides in most cases, there is a need for measuring total cyanides, not only for free
- 74
-------
cyanide. Several devices for automatic measurement of total cyanides are already on
the market, but they have not virtually been applied to the measurement of cyanides
in sewage. It is considered that a lot of troubles will be encountered in these devices
for actual measurement. Therefore, a project is now being carried out to remodel
them through field tests.
2.2.2 AUTOMATIC MEASUREMENT OF TOC
The Area River Basin (Left Basin) Sewerage Authority is conducting automatic
measurement of TOC to determine organic loadings to their sewege treatment plant.
Similar measurement is carried out in Osaka Prefecture for water quality monitoring
of storm water overflow from combined sewer. Models used are different but both
models suffer from clogging at sampling portions and piping. The former model
which sample water is continuously injected by a peristaltic pump, was faced with
such problems as fluctuations in measurements caused by non-uniform entrance of
SS, fluctuations in the base line, precipitation of minerals on the inlet port of the
furnace, and, during earlier stages, corrosion of the piping material due to
hydrochloric acid. On the other hand, in the case of Osaka Prefecture where
intermittent measurement method is used, though the sample line is cleaned by
water while measurement is not carried out, cloggings of the injection valve occurred
frequently. In any case, troubles by SS are unavoidable in the automatic
measurement of TOC of raw sewage. At this moment there are no alternatives but to
reduce these troubles by frequent maintenance and inspection.
2.2.3 AUTOMATIC DETECTION OF SURFACE OIL
Development of automatic devices for surface oil detection for use in sewers
and pumping stations is now being continued by studies financially supported the
Ministry of Construction. Methods under study are measuring fluorescence emitted
by the radiation of ultraviolet rays, measuring reflecting light by the radiation of
infrared rays of two wave lengths, and measuring changes of mutual inductance.
2.3 AUTOMATIC MEASUREMENT OF WATER QUALITY FOR PROCESS
CONTROL OF THE SECONDARY TREATMENT
Parameters requiring automatic measurement to conduct process control of the
secondary treatment include dissolved oxygen, concentration of organic matters
expressed by TOC, etc., MLSS, sludge density, etc. Of these parameters, measure-
ment of concentration of organic matters expressed by TOC, etc. has many
difficulties. But other items are basically in the stage of practice today, though there
remain problems including necessity for frequent maintenance and inspection, and
insufficient accuracy of measurement.
There is no sewage treatment plant in Japan in which air to aeration tanks is
controlled automatically in accordance with the concentration of dissolved oxygen
in tanks. However, studies for them are being performed widely including full scale
experiments. It has been affirmed that automatic measurement of dissolved oxygen
in aeration tanks is possible if calibration of electrodes and cleaning of electrode
surfaces are sufficiently done.
For measurement of sludge density, the method using ultrasonic waves is
extensively used. It is said that since the development of devices for eliminating
75
-------
interferences of air bubbles, measurement accuracies have been improved.
2.4 AUTOMATIC MEASUREMENT OF WATER QUALITY FOR PROCESS
CONTROL OF THE TERTIARY TREATMENT
2.4.1 MEASUREMENT OF NUTRIENTS SUCH AS AMMONIA NITROGEN
BY AUTOMATED COLORIMETRIC ANALYSIS
Water quality measurement of secondary or tertiary effluents can be conducted
by means of automated colorimetric analysis, because SS is low and slime growth is
less.
In the tertiary treatment pilot plant established in the Toba Sewage Treatment
Plant in Kyoto, continuous colorimatric analysis of ammonia nitrogen is carried out,
for automatic control of the break-point chlorination process. Major points to which
special attention was paid in the development of this device are as follows: (1)
output is linear within the range between 0 and 20mg/l of ammonia nitrogen; (2)
dual filtering devices are installed so that they can be cleaned alternative; (3)
disinfection device is installed to prevent growth of slime; (4) color of sample water
is compensated; and (5) automatic calibration is performed at least once a day.
The method used is the salycylate-dichloroisocyanurate reaction with ammonia
(1). This method has an advantage that the color development is stable even in high
concentration of ammonia nitrogen, as compared with the Nesslerization Method
and the Phenate Method. The block diagram of this device is shown in Fig. 2.4.
Samples are heated to approximately 85°C for a short period to prevent slime and
algae growth. But when measuring treated water from the break-point chlorination
process, disinfection by heating is not performed, because measured values become
smaller when samples are heated and of slime control is unnecessary. To filter
sample water, ceramic filters with a mean pore size of 30/u are used. Backwash by air
and water is conducted automatically. Comparison of analytical values by this device
with those by the manual Nesslerization Method is shown in Fig. 2.5. According to
the Figure, when the concentration of ammonia nitrogen becomes about 20mg/l,
analytical values by automatic measurement tend to be smaller. This is because
calibration is performed at Omg/1 and 10mg/l, though absorbance becomes
somewhat non-linear when concentration exceeds about 15mg/l. But as a whole the
results are satisfactory and automatic control of the treatment process is conducted
satisfactorily by means of feed forward control using this device.
For automatic control of coagulant dose in chemical clarification for
phosphorus removal, an automatic measurement device of hydrolyzable phosphorus
based on similar principle is now being developed. For this device disinfection by
ultraviolet rays to prevent slime growth is also considered. Concerning filtration,
synthetic resin filters are examined, not only ceramic ones.
2.4.2 AUTOMATIC MEASUREMENT OF AMMONIA AND NITRATE BY
ELECTRODES
In measuring ammonia and nitrate, use of ion electrodes is one of the best
methods. Therefore, in the above-mentioned pilot plant for the break-point
chlorination process, surveys on application of these measuring devices are
conducted. Since nitrate ion electrodes are interfered by chlorides and others, they
76
-------
are difficult to be used for measuring nitrate in the effluent from break-point
chlorination process. Therefore, they are now used only for measuring nitrate in the
influent.
Measurement of ammonia is carried out for both influent and effluent. In the
latter, because there exists a possibility that the membrane is damaged by residual
chlorine and chloramines, measurement is done after passing samples through
activated carbon columns. The results of experiments so far shows that the
reliability of the measurement by ammonia electrode is somewhat lower compared
with that by colorimetric analysis. Another disadvantage is the short life of the
electrode. It lasts only a few months when used continuously.
Experiments of measurement of nitrate in the secondary treatment water by
means of nitrate electrodes have just begun. The results obtained so far are not so
encouraging. One of the reasons for this is insufficient maintenance and inspection,
so experiments are being continued with more frequent maintenance and inspection.
If continuous measurement of nitrate in the secondary effluent becomes possible by
means of ion electrodes, it will be utilized for automatic control of biological
denitrification process.
2.4.3 USE OF TURBIDIMETERS
The Sewage Works Bureau of Tokyo Metropolitan Government is conducting
surveys at its pilot plant for granular media filtration of the secondary effluent
which is built in the Morigasaki Sewage Treatment Plant, in order to use
turbidimeters for automatic control of granular media filtration. In this pilot plant
various types of turbidimeters are installed. At present, a falling stream type
turbidimeter (scattering light of 23°) is being used for measurement of influent and
effluent turbidity, while for measuring turbidity of backwash waste water the
surface scattering type one is introduced. At though there are some problems of
slime growth in dealing with less treated water, there are virtually no trouble in
measurement. There are corelations between turbidity and SS as shown in Fig. 2.6
depending on the type of the water measured.
In the pilot plant for the tertiary treatment in the Toba Sewerage Treatment
Plant in Kyoto, the surface scattering type turbidimeters are now used for measuring
turbidity of influent to filters, effluent from filters and effluent from chemical
clarifier. Also, studies are being conducted concerning control of fitter backwash by
using turbidity of backwash waste water.
2.4.4 OTHERS
In the pilot plant for filtration in the Morigasaki Sewage Treatment Plant,
Tokyo, in addition to the abovementioned measurement of turbidity, automatic
measurement of TOC, TOD, dissolved oxygen and residual chlorine is performed.
Measurement of residual chlorine is conducted when chlorine is dosed to control
slime growth.
TOC and TOD are of types in which sample water is continuously injected by a
peristaltic pump. They need remodeling including increase in diameter of pipes at
inlet port to the furnace, increase in gas cooling capacity, and providing of activated
carbon column to adsorb hydrochloric gas.
-------
In measuring dissolved oxygen, after flow cells have been introduced which
allow higher contact flow velocity, the maintenance of about once a year has been
sufficient.
2.5 FUTURE ASPECT OF STUDY
Automatic measurement of water quality for process control of the tertiary
treatment gives few problems in the development of devices for it, because it deals
with comparatively clean water. Thus a various kinds of devices have already been
developed and more will be devised in the future when necessary. On the other
hand, automatic measurement of water quality of row sewage and industrial
wastewater discharged into the sewerage system has seldom been conducted in spite
of its high necessity, and there are almost no devices available for it. Monitoring of
heavy metals and other toxic materials is one of the most important factors for the
operation and maintenance of a sewage treatment plant. Therefore, studies in this
field should be positively promoted in the future. Such studies should include, in
addition to those on measuring methods themselves, improvement in methods of
sampling and filtration, methods of slime control, and methods for dissolving heavy
metals contained in solids.
REFERENCE
1) Searcy, R.L., Reardon, I.E. and J.A. Foreman, "A New Photmetric Method for
Serum Urea Nitrogen Determination", American Jour, of Medical Technology, Vol.
33, No. 1, 1967.
- 78
-------
Table 2.1 Inventory of Data Loss During 6 Months Operation of
Automatic Cyanide Monitor
Causes of data loss
Malfunctions of recorder chart drive
Running out of chart paper
Running out of recorder ink (pH)
Running out of recorder ink
(CN-pH)
Power failure (main source)
Fuse blow
Breakage of pH electrode
Clogging of strainer
Malfunction of vacuum pump
Running out of NaOH solution
Shortage of inner solution of refer-
ence electrode
Total
Total period of operation
Period of data loss
(hrs)
92
156
176
429
96
151
138
38
42
80
196
1,594
4,320 (hrs)
Percentage of data loss
(%)
2.1
3.6
4.1
9.9
2.2
3.5
3.2
0.9
1.0
1.9
4.5
36.9
79 -
-------
Primary Effluent of Night Soil
Treatment Plant
5 10'' 2 512 5
Reading of Electrode in Sulphide Free and Anion Exchanged Water, CN (mg/C)
Fig. 2.1 Interferences of Anions Other Than Sulphides with Cyanide
Measurement by Ion-Selective Electrode
- 80
-------
Drain
Vacuum
Pump
Air Com-
pressor
Sampling Tank
Iwater Level Switch
i i
Strainer
pH Con-
trol for
Cyanida
Measurement
n
PH
0
PH
J
To Sample
Preserva- s|_
tion ""
To Waste
To Waste
Fig. 2.2 Block Diagram of Automatic Free Cyanide and pH Monitor
-------
Sensing Element
Scraped Face
Stainless Steel Blade
Fig. 2.3 Cyanide Electrode with Continuous
Scraping Device
- 82 -
-------
Drain
Backwash
Water
Air for
Backwashing
CO
Changeover Valve Changeover Valve
Sampling Cell
25 cc/H
Standard Pure Water
Solution
Mixing Coi
1
-AAAAAA ,
\
Flow-cell of
Colorimeter for
Reference ,. i
(D\. •— '^ • 1>
y^-^ ^H
4.2cc/H
ID 1
Heating Coil
for Color Develop-
ment (40°C)
Flow-cell of
Colorimeter
for Measure-
ment
• To Waste
Alkaline Dichloro-
isocyanurate
Solution
Sample Water
To Waste
Fig. 2.4 Block Diagram of Automated Ammonia Analyzer
-------
20 r
00
15
>,
a
< 10
0)
o
o
P
o
O Influent (Effluent from Filter or
Activated Carbon Contactor)
^ Ettluent from Break-point Chlorina-
tion Process
5 10 15
Manual Nesslerization Method, NH4-N (mg/2)
20
Fig. 2.5 Comparison of Ammonia Nitrogen Concentrations obtained by
Manual and Automated Analyses
84 -
-------
oo
en
20
4 -
S3
"So
10
5 6 7
Effluent Turbidity
O [nfluent to Filter
O Effluent from Filter
D Efluent from Filter - While Chlorine is Dosed
10
20
25 30 35
Influent Turbidity
40
45
10
50
11
55
12
_l
60
Fig. 2.6 Relationship between Turbidity Measured by Falling-Stream Type Turbidimeter and Suspend Solids
-------
Fourth US/JAPAN Conference
on
Sewage Treatment Technology
Paper No. 4
RECENT PROGRESS IN ENVIRONMENT QUALITY
IN JAPAN
October 29, 1975
Washington, D. C.
Ministry of Construction
Japanese Government
86 -
-------
CONTENTS
i NATIONWIDE SURVEY ON MERCURY AND PCB POLLUTION 89
1.1 Findings About Meroury Pollution .....89
1.1.1 Fish and Shellfish 89
1.1.2 Quality of Water 90
1.1.3 Bottom Sediments 91
1.1.4 Soil and Farm Products 91
1.1.5 Controls at Sources of Pollution 92
1.2 Findings about PCB Pollution 93
1.2.1 Fish and Shellfish 93
1.2.2 Quality of Water 94
1.2. 3 Bottom Sediments 94
1.2.4 Soil and Farm Products 95
1.2.5 Controls at Sources of Pollution 95
1.3 Overall Evaluation 96
II CASE STUDIES ON MERCUBY AND PCB POLLUTION 97
2.1 Case Studies on Meroury Pollution 97
2.1.1 The Case in Tokuyama Bay 97
2.1.2 The Case in Jinzu River 103
2.2 Case Studies on PCB Pollution 103
2.2.1 The Case in Lake Biva
2.2.2 The Case in Tsuruga Bay
Ill REVISIONS OF ENVIRONMENTAL AND EFFLUENT STANDARDS ON
MERCURY AND SETTINGS OF ENVIRONMENTAL AND EFFLUENT
STANDARDS ON PCB 105
3.1 Meroury 105
3.1.1 Reasons for Amendment 105
3.1.2 Main Points of Revision 107
3.2 PCB 108
3.2.1 Basic Principles 109
3.2.2 Consideration of Relevant Factors 109
3.2.3 Environmental Quality Limit on PCBs 110
3.2.4 Waste Water Discharge Standards „.. Ill
- 87 -
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3.2.5 Provisional Standard for Removal of PCB-
Contaminated Sediments 112
IV PROVISIONAL STANDARDS FOR REMOVAL OP CONTAMINATED
SEDIMENTS 112
4. 1 Mercury-contaminated Sediments 112
4.1.1 For Sea Area 112
4.1.2 For Rivers and Lakes 113
4. 2 PCB-oontaminated Sediments 113
88 -
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I NATIONWIDE SURVEY ON MERCURY AND PCB POLLUTION
A nationwide survey in Japan on mercury and PCBs (polychro-
linated biphenyls) pollution was done during the period from
July '73 to March «74.
Undertaken at a time when contamination of fish, shellfish
and the environment by mercury and PCBs is becoming worse, the
survey was aimed at obtaining factual data on the actual state
of affairs and investigating the causes of pollution.
The ultimate objectives were, of course, to assure the saf-
ety of fish and shellfish and establish the basic countermeas-
ures required to clear the environment of mercury and PCBs.
Participating in the survey were the Environment Agency,
the Ministry of International Trade and Industry, the Ministry
of Transport, and the Ministry of Construction. Prefectural
governments across the country cooperated in the survey. The
gist of the findings and an overall evaluation are given below:
1.1 FINDINGS ABOUT MERCURY POLLUTION
1.1.1 Fish and Shellfish
Tested for mercury were 22,403 samples of 303 species, of
fish and 6l6 samples of plankton which were collected from 124
inland bodies of water and 144 sea zones.
The majority of the species covered were cleared for fish-
ing and marketing, as their mercury levels were found to be be-
low the provisional standards. But some fish species caught
in Minamata Bay and Tokuyama Bay, where voluntary fishing rest-
rictions are already in force, exceeded the provisional limits.
So did some species caught in the sea off Naoetsu in Niigata
Prefecture — such as "ishimochi (Argyrosomus argentatus)","ka-
nagashira (Lepidotrigla microptera)", "magarei (Limanda yoko-
hamae)" and "akamutsu (Upeneus bensasi)" — and some species
caught in the inner parts of Kagoshima Bay — such as "tachiuo",
89 -
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"madai", "akana", "anago" and "raaaji". Voluntary fishing curbs
have been put into effect on these species following the earli-
er discovery of high mercury presence by Niigata and Kagoshima
prefectural governments.
Fish and shellfish in the sea off Naoetsu and inner parts
of Kagoshima Bay must be kept under continued surveilance. The
fact that investigations of bottom sediments failed to reveal
the causes of pollution in these areas calls for a more intens-
ive probe into the mechanism of contamination, so that neces-
sary countermeasures can be formulated.
Fish caught in nine rivers showed mercury levels well above
the provisional standards. The earlier surveys of these rivers
had resulted in similar findings except for one in Nagasaki
Prefecture, and the inhabitants living along the rivers have
already been given dietary guidance by the authorities.
The contamination of these rivers may be spontaneous since
many of them flow through regions where there has historically
been some pollution originating from mercury mines. A close
inquiry, nevertheless, is required to determine the precise
cause of river pollution and the effectiveness of possible
countermeasures by implementing such steps as reducing the dis-
charge of pollutants at known sources, removing bottom sedi-
ments that are dredged where necessary, plus conducting regular
checks on fish and shellfish in the interim.
Surveilance of foodstuffs is also being maintained in fish
markets to assure the safety of fish and shellfish that are
channeled to consumers.
1.1.2 Quality of Water
The water aspect of the mercury survey involved 3,768 samp-
les taken from 331 rivers, 156 ports and harbours, and 147 sea
areas. Seventy-six samples, or two percent of the total, were
found to contain total mercury levels exceeding 0.005 ppm.
The samples topping the environmental quality standards
90
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were from the Mukagawa River in Hokkaido, the upper reaches of
of the Tone River near Shibukawa in Gumma Prefecture, the Shin-
gashi River in Tokyo, the Torigai River in Osaka (a tributary
of the Kanzaki River), Minamata Bay, and a canal linked with
Toyama Port. The causes of pollution in these areas need to
be clarified so that the necessary counterraeasures can be in-
stituted.
1.1.3 Bottom Sediments
A total of 5»l86 samples of bottom sediments were examined
for mercury. They were collected from almost the same areas
where the water-test samples were taken — 332 rivers,155 ports
and harbours, and 148 sea zones. Samples from 16 rivers and
nine ports and harbours — i.e., 120 samples, or 2.3 percent of
the total — registered mercury values in excess of the pro-
visional standards for removal of polluted sediments.
Dredging work has already been completed or is in progress
in most of these bodies of water. Sections that need dredging
should be designated promptly in other areas after detailed
investigations.
1.1.4 Soil and Farm Products
Samples of soil were tested for mercury at 707 spots —ord-
inary tests at 469 places and close examinations at 58 places
in the vicinity of factories handling mercury.
Values recorded in ordinary tests, in terms of total mer-
cury, ranged from ND (not detectable) to a maximum of 5*36 ppm,
the great majority of them being below 1.5 ppm. It seems safe
to conclude from this that densities of total mercury contained
in common specimen of soil is less than 1.5 ppm.
The samples were analysed for organic mercury. But no
appreciablelevels of methyl mercury and ethyl mercury were
detected.
The test produced readings ranging from a low of 0.07 ppm
- 91
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to a high of 67 ppm, with the great majority of the samples be-
ing below 1.5 ppm. Practically no methyl mercury nor ethyl
mercury was detected.
Tests on farm products were conducted at 702 spots —ordin-
ary tests at 464 places and scrutiny at 238 places.
Samples of unhulled rice involved in ordinary tests showed
values ranging from ND to a high of 0.17 ppm. The great
majority of the recorded readings were below 0.01 ppm. Methyl
mercury and ethyl mercury were practically nonexistent.
Total mercury readings resulting from close examinations
ranged from ND to 0.12 ppm, the great majority of them below
0.01 ppm — not necessarily high compared with the results of
ordinary tests. Practically no methyl or ethyl mercury was
in evidence.
1.1.5 Controls at Sources of Pollution
Appropriate treatment or disposal of waste water and refuse
is imperative to deter further environmental disruptions.
The situation has remarkably improved with regard to waste
water — with strict controls being enforced across the country
— instead of in limited bodies of water as before, under the
discharge standards established in May, 1971> on the basis of
the Water Pollution Control Law.
The discharge standards were strengthened further in August
1974. Especially noteworthy is a fact that the main sources
of mercury pollution — factories that turn out caustic soda by
using mercury and vinyl monomer and acetoaldehyde by using ace-
tylene — have been shut down or have carried radical changes—
either in production processes or by installing self-containing
waste-water facilities.
Factories that were built after the establishing of custody
and disposal standards on industrial refuse in September, 1971,
in line with the Waste Disposal and Public Cleaning Law are be-
ing given guidance so that their refuse is properly disposed of
92
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in accordance with these rules.
As for factories that existed before the standards were
fixed, the assumption is that as a general rule, their refuse
is being safely gotten rid of or adequate counterraeasures are
in effect. There are cases in which refuse is buried or in
custody in the factory grounds, some of it outside the grounds.
There seems to be no problem, judging from the quality of water
in the neighbouring body of water. There are also factories
where concrete, clay and other materials are as covers to keep
pollutants from flowing or seeping away when it rains. But
available information is, admittedly, still insufficient in
some oases.
1.2 FINDINGS ABOUT PCS POLLUTION
1.2.1 Fish and Shellfish
Checks on fish and shellfish were carried out in 20 bodies
of water — all of which had shown questionably high levels of
PCBs in the previous surveys — with 3,369 samples being tested.
The estuary of the Tama River in Tokyo and the Nagara Hiver in
Aichi Prefecture, in addition to the nine areas where self—
restrictions on fishing were instituted in 1973, were found to
be more polluted than allowed under the provisional standards.
Similar curbs have been enforced in the heavily contaminated
Taraa and Nagara river sections following earlier findings by
the responsible prefectural governments.
Factories handling PCBs have existed along these rivers in
the past, and their pollution is fully accountable from the
volumes of PCBs consumed in the plants and the extent of con-
tamination of bottom sediments. What needs to be done now,
therefore, is to make sure that stocks of PCBs are recalled and
kept in the hands of the authorities until they are disposed of.
Needless to say, the ban on their use, to be detailed later, is
imperative.
93
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Of particular importance is the installation of sophist-
icated equipment for material screening and waste—water disp-
osal in used-paper recycling plants since water discharged by
these plants sometimes contain minute amounts of PCBs originat-
ing from pressure-sensitive copying paper and other types of
secondhand paper. Removal of contaminated bottom deposits in
accordance with relevant standards, to be fixed shortly, and
other environmental cleaning measures are promptly for,with de-
tailed surveys made mandatory when necessary.
Appropriate levels of surveilance are also maintained at
fish markets to ensure the safety of fish and shellfish sold
there.
1.2.2 Quality of Water
Assayed for PCBs as affecting the quality of water were
l,28l samples from 208 rivers, 28 ports and harbours,and 46 sea
areas where fish and shellfish contamination had posed a prob-
lem in previous surveys or where quality of water examinations
had produced 1 ppm or more. Fifty-five samples, 4«3 percent
of the total, logged levels higher than 0.0005 ppm. These were
collected from 18 rivers and four sea zones. Inquiries into
the causes of pollution in these cases are in order,with neces-
sary countermeasures to be taken afterward.
Compared with the previous year's findings, the situation
improved on the whole, with reductions recorded both in terms
of the number of contaminated samples and PCB densities.
1.2.3 Bottom Sediments
Bottom sediment tests were held on 1,789 samples from 258
rivers, 33 ports and harbours, and 58 sea areas. Samples from
14 bodies of water showed maximum PCB readings in excess of 50
ppm. Maximum levels were between 10 and 50 ppm in 37 other
areas and between five and lOppm in another 21.
Sediment removal work has been completed in some of these
94 -
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regions. As for the remainder, removal or other counter-
measures are called for on the basis of the provisional removal
standards to established shortly, with detailed investigations
to be carried out where necessary.
Exceedingly high levels of PCB pollution were recorded in
the previous year's survey, topping 10,000 ppm in some places,
but counter-measures have been taken in the areas concerned. As
a result, the latest survey did not such extraordinary peaks.
1.2.4 Soil and Farm Products
PCB checks on soil were conducted on samples from 105 pla-
ces in the vicinity of factories and other establishments hand-
ling PCBs in five prefectures and two major cities with a gre-
ater measure of self-autonomy accorded by law. Recorded dens-
ities ranged from ND to 59 ppm, the great majority of them be-
low 0.1 ppm.
Farm products were found to be practically free of PCBs.
1.2.5 Controls at Sources of Pollution
A total ban has been imposed on the use of PCBs in manufac-
turing such goods as copying paper, paint and ink. The use of
PCBs in such products as heat exchangers, heaters, transformers
and condensors is also prohibited as a general rule. Owners of
these equipment already in use are urged to keep them under
strict control, and in the case of products in which PCBs serve
as a heat medium,manufacturers are under orders to replace them
with substitutes.
Directives have been issued to institute proper procedures
for the recall and custody of copying paper containing PCBs and
make sure that they are not used for reclaimed paper product-
ion.
Components containing PCBs are being removed from discarded
home electrical appliances with the cooperation of local gov-
ernments. The Appliance PCB Disposal Association has been set
95
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up to collect such components and keep them in custody until
they are disposed of, pending the establishment of relevant
technology. The association plans to extend its services to
the disposal of transformers, condensers and the like disjoined
from heavy-duty equipment.
While PCB contamination of waste water has improved on the
whole from the previous year as a result of guidance based on
the provisional standards, controls will further strengthen-
ed under the full-fledged standards to be set shortly.
1.3 OVERALL EVALUATION
As a result of the latest survey, without an equal scale-
wise in foreign countries, environmental realities in Japan as
regards fish and shellfish, farm products,the quality of water,
and soil have been brought to light, practically wiping away
anxiety about unknown dangers of mercury and PCB pollution.
With voluntary fishing restrictions introduced in the
bodies of water which were found to be heavily polluted, it can
be said that a system to avert adverse effects on the health of
people through the intake of contaminated fish and shellfish
has been set up.
However, as is clear from the findings of the survey,envir-
onmental health has yet to be restored in these areas, although
there has been improvement at the sources of pollution in the
overall picture.
Our target is an environment which would enable people to
eat fish and shellfish without any fear of health damage. For
this purpose, the relationship between polluting factors and
contaminated fish and shellfish must be cleared up.
Polluting elements are traceable through periodical checks,
except for some bodies of water where detailed investigations
are needed. For the time being, therefore, emphasis should
be placed on prompt implementation of measures to improve the
96
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quality of water, bottom sediments and reduce the release of
pollutants at their sources, as it was pointed out before.
Parallel with the effort, necessary detailed investigations
should be promoted, with countermeasures based on their find-
ings to be worked out quickly.
II CASE STUDIES ON MERCURY AND PCB POLLUTION
2.1 CASE STUDIES ON MERCURY POLLUTION
2.1.1 The Case in Tokuyama Bay
Tokuyama Bay is a good natural harbour and is located at
the western part of Honshu-island, and fronts on Seto Inland
Sea. Tokuyama City (population 105,000) and Shin-nanyo City
(population 34»000), both are industrial cities, are face at
this bay.
Here, Tokuyama Soda Company (1952) and Toyo Soda Company
(1956) had been produced caustic soda and chlorine by mercury
caustic process.
The total amount of mercury used and the estimated amount
which had been discharged into the bay by these two factories
are shown in Table 1 t
Table 1
Names of the Co.
Names of the
factories
Date of the
investigation
Total amount of
mercury used(-t)
Mercury dis-
charged into
waste water (t)
Tokuyama Soda Co.
Tokuyama
1973
703.2
3.69
Toyo Soda Co. Total
Nanyo
June 7, 1973
558.6 1,261.8
2.95
6.64
97
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Since it was already known that the fish and shellfish in
this bay were highly contaminated by mercury, from 1.0 to 1.5
ppm, a close survey was undertaken on water, bottom sediment
and marine products, when the nationwide survey was done in
1973 as one of the water areas that seriously polluted by mer-
cury.
As to the result of water quality survey,all the 69 samples
were "not detectable".
On the contrary, allthe samples of bottom sediments showed
mercury existence. (Table 2)
Table 2 The result of bottom sediments of Tokuyama Bay
Numbers of Total mercury
° 8 survey Nrs of Nrs „ _ ... _ „
points
A Sea area g
B 44
C
D
Sub-total
Toyo Soda
Tokuyama Soda
Tokuyama Soda
Sub-total
Total
121
40
416
2
2
1
5
421
samples deteo1
131 131
80 80
44 44
121
40
416
2
2
1
5
421
121
40
416
2
2
1
5
421
, I"lf tUl
d
6.64
4.56
3.85
2.63
0.91
5.15
13.32
0.56
7.50
1'ij.ii. — e
0.07 -
0.25 -
0.45 -
0.13 -
0.04 -
4.16 -
5.83 -
0.56 -
'IcUL.
31.57
18.98
7.25
19.50
2.96
6.14
20.8
0.56
20.8
The Department of Technology of Yamaguchi University est-
imates according to the results of these survey and also the
results of survey boring which were undertaken at the same
time that the amount of mercury discharged from these two fact-
ories into this bay should be 13 - 14 tons (4 centimetre be-
neath from the surface of the sea bottom) upto 36 tons (two me-
tre ditto).
Many fish and shellfish were caught in this bay and analys-
98 -
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ed as to mercury. Figure 2 shows the rslationship between
concentration of mercury in fish and shellfish and concentrat-
ion of mercury of bottom sediments.
Fig. 1 Map of Tokuyama Bay
the Factories
99 -
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Pig. 2 Relationship between concentration of mercury in fish
and shellfish and concentration of mercury of bottom
: sediments
c--" —^ Black sea bream
0.7
x
. o
1 0.5
a
ft
A
m
03
§
•H
•p
<&
0)
o
C
o
0.1
Sea perch
Sea chub
Gizzard shad
Short-necked clam
Plankton
Sea
Black sea bream
Short-necked clam
o
Gizzard shad
___ . - O
Plankton
Concentration of Hg in the bottom sediment(total Hg dry wt)
100
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Also a survey for mercury content in the hair of the inhab—
itants(60 men and women) living along the coast of Tokuyama Bay.
Table 3 shows mercury content in women1a long hairs.
Table 3
Sample
No
No 2
(70 yrs
of age)
No 5
(57 yrs
of age)
No 15
(23 yrs
of age)
No 16
(52 yrs
of age)
Length of
hair( cm)
0-10
10 - 15
15 - 19
19 - 22
22 - 25
25 - 27.5
27.5- 30
Mean
0-10
10 - 15
15 - 20
20 - 25
25 - 29
29 - 33
33 - 37
37 - 41
41 - 44
44 - 47
47 - 50
Mean
0-4
4 - 6.5
6.5- 9
9 - 12.5
Mean
6 - 25 "
25 - 35
35 - 45
45 - 50
50 - 55
55-60
Mean
Conc.(ppm)
7.8
8.0
8.8
9.1
9.1
9.6
9.5
8.84
10.9
8.1
7.1
7.3
6.9
6.9
8.2
10.7
13.4 I
13.4
12.9
9.62
4.61
4.61
4.71
4.90
4.71
5.30
4.90
3.73
3.24
2,75
2.35
3.71
Sample
No
No 20
(25 yrs
of age)
No 29
(21 yrs
of age)
i
No 60
(42 yrs
of age)
i
No 61 ;
(42 yrs ;
of age)
Length of
hair (cm)
0-10
10 - 17
17 - 24
24 - 32
Mean
0-10
10 - 18
18-24
24-30
Mean
0 - 26
26 - 36
36 - 46
46 - 54
54 - 60
60-65
65 - 69
69 - 72.5
72.5- 76
Mean
0-10
10 - 15
15 - 19
19 - 23
23 - 28
28 - 33
Mean
Cone. (ppm)
2.35
2.94
3.82
3.94
3.26
7.36
8.04
6.67
7.36
7.36
3.14
3.14
2.65
2.94
2.55
2.75 i
3.24 i
3.53
3.82
3,08
2.8
2.8
2.2
2.4
2.6
2.4
2.53
Conclusion
1) Dicharged quantities of mercury from soda-producing factor-
ies should indicate the quantities of environmental pollution,
but the facts are not so simple because of difficulty to get
101
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continuous records of effluent conoetration,and because of the
differences of water areal extent or levels of maintenance of
factories.
2) There are little chances to detect mercury in water quality
survey,and there is a problem as to the quantitative analysis
limit in the case of sea water.
3) Mercury contended in bottom sediments could show the quan-
tities of mercury discharged or the state of the waste water
treatment of the factory concerned.
4) When mercury concentration in surface potion of bottom se-
diments doesn't exceed 2 - 2.5 ppm (dry wt), the concentration
of mercury in fish meat will not exceed 0.4 - 0,5 ppm (in the
case of sea water).
5) Fish are good index for monitoring to pollution because of
their bioconcentration of methyl mercury.
6) Generally speaking, much—eating and bottom—inhabited fish
indicate greater magnification. Crustacea and plankton don't
indicate greater magnification.
7) Hairs of inhabitants along the oast concerned, when analys-
ed, tell the history in the past of mercury pollution for fish
and water area concerned.
8) It is scheduled that the bottom sediment of Tokuyama Bay
will begin to be removed within this year(concentration over
15 ppm). It is anticipated that we could get the answer whet-
her vastly spreading mercury in the bottom sediments affect
fish pollution or high concentration of mercury in limited
spots affect fish pollution.
9) Middle-sized fish have 4-5 years of life, and also biolo-
gical half-period of methyl mercury is relatively long for 1 -
2 years, we should consider that there are time-lags between
the concentration of mercury in fish and the environmental
clean-up performances.
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2.1.2 The Case in Jinzu River
l) Around in the time 1967, it was disclosed that dace in Jinzu
River (flows through Toyama prefecture) were highly polluted by
meroury( over 3 ppm), and mercury in dace was in the form of
methyl mercury.
2) According to the results of surveys, the cause of pollution
was suspected to be the pollution caused by a pharmaceutical
company situated along the coast of a branch river of Jinzu Riv-
er.
3) The production of "thimerosal (an organic mercuric disinfec-
tant, sodium ethyl-mercury thiosalioylate)" was rapidly increas-
ed in 1968 to 1969.
4) According to the result of the survey held by the Institute
of Hygiene of Toyama Prefecture it is disclosed that there were
high concentration of meroury(2,300 ppm, including 32 ppm of
methyl-mercury)in the bottom sediments near the discharge point
of the factory.
5) Halting the production of "thimerosal,merthiolate" and re-
moval of bottom sediment which containing high concentration of
mercury, mercury concentration in "ayu (sweetfish)" restored
cleanliness after one year, but in the case of dace it took
four years to lessen the value of mercury concentration.
2.2 CASE STUDIES ON PCB POLLUTION
Production of PCBs in Japan began in 1954, and by 1970 out-
put reached 11,000 tons per year. But the advent of concern
over possible pollution brought the output down to 6,800 tons
in 1971, and in 1972 production was totally halted. PCBs had
also been imported prior to World War II, although statistics on
the quantity are not available. During the period from 1954
to 1972, the total amount of PCBs use in Japan is estimated ap-
proximately 53,000 tons.
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As to 2.2.1 (the case in Lake Biwa) and to 2.2.2 (the case in
Tsuruga Bay) another paper is prepared.
104 -
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Ill REVISIONS OF ENVIRONMENTAL AND EFFLUENT STANDARDS ON
MERCURY AND SETTINGS OF ENVIRONMENTAL AND EFFLUENT
STANDARDS ON PCB
3.1 MERCURY
Revisions in the environmental quality standards and the
waste water discharge standards relating to mercury and changes
in the relevant measuring methods were enforced on Sept. 30,
1974. This action was done on a report presented to Director-
General of Environment Agency in April, 1974, by the Central
Council for Control of Environmental Pollution.
3.1.1 Reasons for Amendment
Under the old environmental standards on water quality,both
alkyl mercury and total mercury were to "not detectable". But
quantities of alkyl mercury smaller than 0.001 ppm could not be
measured by gas chromatography and thin layer chromatograph-
dithizon extraction absorptiometry, the procedures deemed appr-
opriate when the standards were established in 1971- Likewise,
there was a quantitative limit of 0.02 ppm for total mercury by
dithizon extraction absorptiometry, the procedure practicable
for administrative purposes in those days.
The "not detectable" level for alkyl mercury was set be-
cause of adverse effects on the health that result from eating
heavily contaminated fish and shellfish over a long period of
time and the difficulty of keeping it out of tap water.
In the case of total mercury, the intake from foods was
subtracted from the intake level beyond which the metal would
begin to accumulate in the human body, to figure out the intake
from drinking water. The "not detectable" limit was institut-
ed by considering the intake ascribable to drinking water, the
difficulty of keeping the metal out of tap water, and a safety
margin.
Both standards were not considered strict enough, but there
was no choice but to be content with them because of the limit-
- 105 -
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ed measuring capabilities at the time. It was also in consid-
eration of these limitations that the effluent standards for
mercury were set at the same level as the water quality stand-
ards when 10 times as much values as under the environmental
quality standards were allowed for the discharge of other harm-
ful substances.
Prompted by the following developments and in view of the
urgent need to resolve the mercury pollution issue, the envir-
onmental quality standards and the waste water discharge stan-
dards relating to mercury were revised to update themi (l) Ad-
vances in analysis technology and the spread of more sophistic-
ated analysing devices have made it possible to analyse low
densities of mercury; (2) Provisional tolerance levels of mer-
cury were fixed for fish and shellfish; (3) More data on envir-
onmentalpollution and fish and shellfish contamination have be-
come available, permitting studies on the interrelationship be-
tween them.
Note 1: Technological advances— The measurable limit
on total mercury by flameless atomic absorptiometry and
on alkyl mercury by gas chromatography and thin layer
chromatograph-flameless atomic absorptiometry has been
improved to 0.0005 ppm, remarkably better than before.
Note 2: Provisional tolerance levels on fish and
shellfish— The maximum permissible levels established
provisionally by the Health and Welfare Ministry are 0.4
ppm in total mercury and 0.3 ppm in methyl mercury.
Note 3s Environmental pollution and fish and shell-
fish contamination— While surveys indicate that the mer-
cury pollution of fish and shellfish has much more to do
with bottom sediments than with water, it seems safe to
say that if mercury levels in water are kept to the range
of 0.00§ Ppm and 0.001 ppm, fish and shellfish living in
the sea, lakes and marshes can stay well below the pro-
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visional limits.
3.1.2 Main Points of Revision
The revised standards relating to mercury are given below.
Revised Standards on Mercury
^^^
Environmental
A! 1 o 1 -i + -rr
v^uaj.iTy
Standards
Waste ¥ater
Discharge
Standards
^
Total
Mercury
Alkyl
Mercury
Total
Mercury
Alkyl
Mercury
Standard
Value
0.0005
ppm
2)
Not Detectable
0.005
ppm
4)
Not Detectable
Measuring
Method
Flameless Atomic
Absorptiometry
Gas Chromatography
and Thin Layer
Chromato graph—
Flameless Atomic
Absorptiometry
Flameless Atomic
Absorptiometry
Gas Chromatography
and Thin Layer
Chromatograph-
Flameless Atomic
Absorptiometry
Note 1: The standard value for total mercury stands for
the annual mean value. It is to be eased to 0.001 ppm or
less for rivers when there is no doubt that their pollut-
ion is spontaneous.
Note 2: The phrase "not detectable" applies to cases
other than when the presence of alkyl mercury is detected
by gas Chromatography and thin layer chromatograph-flame-
less atomic absorptiometry.
Note 3: ¥hile the waste water discharge standard of
107
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0.005 for total mercury is 10 times as much as the level
allowed under the environmental quality standards, waste
water released into a normal body of vater is presumably
diluted quickly to reach readings satisfying the environ-
mental quality standards. Since the discharge limit ap-
plies to maximum levels of pollution, the average quality
of released waste water will have to be better than 0.005
ppm.
Note 4« The discharge standard for alkyl mercury
should be kept as strict as under the environmental qual-
ity standards because of its tendency to accumulate heav-
ily in fish and shellfish.
3.2 PCB
The water quality panel of the Central Council for Con-
trol of Environmental Pollution has submitted a report on
standards to fight PCB pollution to the Director General of
the Environment Agency at the end of the year 1974. The
panel's recommendations involved environmental water qual-
ity standards relating to PCBs, relevant waste water dis-
charge standards, provisional standards for removal of PCB-
contaminated sediments, and the analytical method to be
employed.
The report was drafted in response to a request from
the Environment Agency, which took the initiative to follow
up on the earlier instituted measures to curb mercury pol-
lution.
The agency's battle against PCB pollution has been bas-
ed on decisions made by the PCB Pollution Countermeasures
Council set up in April, 1972, and the Mercury Pollution
Council created in June, 1973. The discharge of PCB-
tainted waste water has been regulated on the basisof pro-
visional guidelines presentedin July, 1972, while broad
controls havebeen enforced on the production end use of
108
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PCBs under the Chemical Substances Control Law.
In spite of these efforts, the PCB pollution of public bod-
ies of water— resulting from the release of contaminated waste
water from such facilities as the workshops of waste paper
dealers— persists. Hence the agency's request for consider-
ation of new anti—PCB measures.
Here are the main points of the report on PCB standards
from the water quality panel.
3.2.1 Basic Principles
(l) The guiding principles in establishing the proposed
sets of standards should be to keep down PCB levels in water
and sediments so that the PCB level in fish and shellfish —
whether accumulated directly from the contaminated environment
or through the food chain— will not exceed 3 ppm as the pro-
visional limit for foods. (See note)
(2) Allowances should be made for particular conditions of
PCB pollution in diffrent public bodies of water and for the
accuracy of PCB measurements.
(3) Waste water discharge standards on PCBs should be est-
ablished by considering the related environmental quality stan-
ards and the way PCB-contaminated waste water spreads when it
is released from an outlet into a public body of water.
Note: The 3 ppm permissible limit on PCBs applies to
the edible parts of fish and shellfish caught in inland
seas, bays and other bodies of water. The provisional rule
was set on the basis of recommendations made by the Pood
Sanitation Research Committee to the Health and Welfare
Ministry on Aug. 14, 1972.
3.2.2 Consideration of Belevant Factors
(l) Concentration Ratio
The following formula should be used as the definition of
the ratio of PCB concentration in fish and shellfish, a key
109 -
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factor in relation to the proposed sets of standards:
PCB concentration
PCB density in edible parts of
fish and shellfish
PCB density in environmental water
Table 1 shows PCB concentration ratios obtained from ex-
periments using this equation. The figures range from 5>607
to 8,582 and average 7,360. A proper ratio would be around
10,000, first because "hamachi" (young yellow-tails) and eels,
the fish used in the experiments, are species more apt to ac-
cumulate PCBs and, second, because concentration ratios in
cases where PCB densities actually pose a fish and shellfish
contamination problem— such densities would be a little lower
than the range of one to five ppb, the PCB level of water in
which the fish was kept— would be slightly higher than what
the experiments showed. A third factor to be considered in
this connection is the food chain.
(2) Measuring Methods for PCBs
Gas chromatography should be used to measure PCBs in envir-
omental water. The quantitative measurement limit under this
method is 0.0005 ppm. As for PCBs in sediments, another meas-
uring method is prescribed.
3.2.3 Environmental Quality Limit on PCBs
"Not detectable" is the recommendation on PCBs in environ-
mental water, because, while the provisional PCB limit foods
(3 ppm) and the proper PCB concetration ratio (10,000) suggest
a ceiling of 0.0003 ppm, gas chromatography makes it possible
to measure up to 0.0005 PPm. PCB densities in water should
be obtained by the following formula:
110 -
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PCB density(ppm)
PCB density in edible parts of fish
and shellfish (ppm)
PCB concentration ratio in fish and
shellfish
3 ppm
= 0.0003 ppm
10,000
The setting of the "not detectable" environmental limit is
not to be taken to mean that pollution up to 0.0005 ppm will be
permitted. Currently clean water quality should be protected
from degradation as much as possible.
3.2.4 Waste Water Discharge Standards
(l) Regulation Value— 0.003 ppm in PCBe
Based on the provisional PCB limit for foods and the appro-
PCB concentration ratio, PCB densities in environmental water,
are to be held to 0.0003 ppm or less. Since it is safe to
assume that discharged waste water is diluted 10 times or more
in a normal body of water, the regulation value is to be set at
0.003 ppm.
(2) Enforcement of Rule
A) The stiffened rule is not be enforced for a month after
its promulgation to provide time in which to thoroughly inform
industrial plants and other business establishments of the
change. (Guidance has been exercised to keep PCB readings in
discharged waste water below the earlier quantitative limit of
0.01 ppm under the above-mentioned provisional guidelines.)
B) Toilet paper manufacturing companies, using waste paper
as material, are to be granted a one-year grace period in view
of the particularly serious implication of the new rule for
them in waste water disposal,.
(3) Measuring during Grace Period
A) Targets for control of the quality of waste water, with
0.003 ppm as the permissible limit, are to be fixed for applic-
111
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ation to toilet paper producers during the grace period.
B) Administrative guidance is to be stepped up on waste
paper collectors and manufacturers using such paper so that
PCB-containing "no-carbon" copying paper will be handled separ-
ately from other kinds of junk, will not get mixed in product-
ion materials, and will be kept in strict custody once collect-
ed.
3.2.5 Provisional Standard For Removal of PCB- Contaminated
Sediments
Considering statistical analysis on the relationship bet-
ween the PCB pollution of fish and shellfish and PCB densities
in the same areas based on national environmental surveys, sed-
iments with a reading of around 10 ppm require removal.
The present dredging technology should make it feasible to
bring the contamination level down to about 10 ppm. The removal
standard ia thus to be set at 10 ppm.
The imposition of tougher standards should be considered
for bodies of water where the 10 ppm level is deemed inadequate
to arrest the worsening PCB pollution of fish and shellfish.
IV PROVISIONAL STANDARDS FOR REMOVAL OF CONTAMINATED
SEDIMENTS
4.1 MERCURY^-CONTAMINATED SEDIMENTS
4.1.1 For Sea Area
Provisional standards for removal of mercury-contaminated
sediments should be obtained by the following formulat
C = 0.18 x -45- x -i- (ppm)
Here, C t Value of mercury density of sediments
AH: Mean value of the difference of sea levels
between ebb and flow (m)
j : Dissolving ratio according to "the Method of
112
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Survey for Bottom Sediment"
s t Safety factor
l) 10 for sea areas in which no fishing
activities are performed.
2) 50 for sea areas in which fishing activ-
ities are performed, and in the case that
the ratio of the catch for fish and shel-
lfish which intake sediments and organ-
isms sticking to sediments to the total
catch is approximately less than ^.
3) 100 for sea areas in which fishing activ-
ities are performed, and in the case that
the ratio of the catch for fish and shel-
lfish which intake sediments and organ-
isms sticking to sediments to the total
catch is approximately exceeding than ^.
Also, it is allowed that an adoption of
stricter value of safety factor according
to the special conditions, e.g., habit of
diet.
Here, "fish and shellfish which intake
sediments and organisms sticking to sedi-
ments" are sorts of lobsters, crabs etc.
4.1.2 For Eivers and Lakes
In the case of rivers and lakes, sediments with a reading
of over 25 ppm require removal. However, in the case of est-
uaries which are strongly affected by ebb and flow, it should
be applied correspondingly in the case of sea areas, on the
contrary in the case of sea areas which are affected strongly
by the coastal current, it should be applied correspondingly in
the case of rivers and lakes.
4.2 PCS-CONTAMINATED SEDIMENTS
As stated in the paragraph 3.2.5.
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Fourth US/JAPAN Conference
on
Sewage Treatment Technology
Paper No. 3
STUDIES ON ADVANCED WASTE TREATMENT
October 24, 1975
Cincinnati, Ohio
Ministry of Construction
Japanese Government
- 114 -
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STUDIES ON ADVANCED WASTE TREATMENT
1. Current and Future Studies on Advanced Waste Treatment in Japan 116
M. Kashiwaya, PWRI, Ministry of Construction
2. Outline of Research Activities on Advanced Waste Treatment in Public
Works Research Institute, Ministry of Construction 120
M. Kashiwaya, PWRI, Ministry of Construction
3. Direct Filtration of Secondary Effluent 124
M. Kashiwaya, PWRI, Ministry of Construction
4. Metal Salts Precipitation 156
S. Ando, S. Kyosai and M. Kashiwaya, PWRI, Ministry of Construction
5. Lime Precipitation and Recovery of Calcium Carbonate 205
5. Kyosai and K. Murakami, PWRI, Ministry of Construction
6. Carbon Adsorption and Regeneration of Waste Carbon 227
S. Ando and K. Murakami, PWRI, Ministry of Construction
7. Breakpoint Chlorination 282
H. Watanabe and K. Murakami, PWRI, Ministry of Construction
8. Phosphate Removal in an Activated Sludge Facility by Alum Addition 295
T. Annaka, K. KoboriandK. Murakami, PWRI, Ministry of Construction
9. Pilot Plant Studies of Phosphorus Removal from Secondary Effluent
to Protect Lake Biwa . . . 316
A. Sugiki, Japan Sewage Works Agency
- 115
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CHAPTER 1. CURRENT AND FUTURE STUDIES ON ADVANCED
WASTE TREATMENT IN JAPAN 117
116
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1. CURRENT AND FUTURE STUDIES ON ADVANCED WASTE TREATMENT
IN JAPAN
In recent years in Japan, so many experiments of pilot plant scales for advanced
waste treatment have come to be carried out. These are roughly classified into the
following three cases.
i) A case sponsored by the Central Government and assisted by local government
ii) A case conducted by local government independently or in cooperation with
manufactures
iii) A case conducted by a manufacture alone
Advanced waste treatment now under study in Japan can be classified as to
objectives as follows.
i) Experiment for upgrading the secondary effluent from the activated sludge
process
Major studies include: study of the effects of coagulant dose into aeration tank,
study of effects of coagulant dose on biological treatment, and study on the
selection of filter type for direct filtration of secondary effluent and selection
of their media sizes and conponents.
ii) Experiment on tertiary treatment purposes for phosphorus removal from the
secondary effluent
So many pilot-scale experiments on chemical-sedimentation process using lime
or metal salts as coagulants have been carried out.
Purposes of the studies are: improvement of settling efficiency, improvement of
phosphorus removal efficiency, improvement of organic matter reduction ef-
ficiency, and thickening and dewatering of the sludge.
Experiments on recovery of used coagulant from settled sludge have not yet
been reported.
iii) Experiments for the removal of residual organic matter from secondary effluent
Experiments on granular activated carbon adsorption of secondary effluent or
effluent from chemical-sedimentation have been reported one after another.
Also, study on the regeneration for spent carbon is also prevailing.
Granular activated carbon adsorption process has been practiced for the treat-
ment of organic type industrial wastes. There are many factories with a large-
scale waste water treatment facility equipped with a regenerator for spent
carbon.
Oxidation of organic matter of waste water by ozonation is rarely so long as
the pilot plants are concerned, because the electric costs are so expensive in
Japan.
iv) Experiments on biological nitrofication and denitrofication process.
Experiments of three-stage biological nitrofication and denitrofication has been
carried out with a pilot plant annexed to a small-scale sewage treatment facility.
- 117
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This is because the secondary effluent from the small-scale sewage treatment
facility is discharged into irrigation channel and nitrogen in the effluent ham-
pers the growth of rice plant.
Strong opposition has been made by the farmers against the pollution of their
paddy fields with nitrogen.
High concentration of nitrogen in the supernatant developed from the night
soil digestion facility is also warned against by the farmers.
For this reason, demonstration plants for biological nitrofication and denitrofi-
cation were installed at several places and are now in operation.
v) Removal of ammonia by physico-chemical process
Experiments on ammonia stripping, ion exchange of ammonium by making use
of natural zeolite, and breakpoint chlorination have been conducted at several
places each. Also, an experiment in which NOx in stack gas is reacted upon
ammonia in sewage in order to vent ammonia into the open air in the form of
N2 gas is going to be started on a pilot plant scale by a private company.
There has not been any trial for recovering ammonia in sewage in the form of
industrial raw material or fertilizer.
vi) Experiments on the removal of inorganic substance in sewage
In Japan, water shortage is expected to take place in future in Kanto and
Kansai and other developed areas.
Also, ground depletion areas (ground subsidence) have been reported increas-
ingly as a result of overpumping of ground water.
Against this backdrop, move toward using as industrial water the tertiary
effluent of sewage has been intensified. Reflecting the trend, a fair number of
pilot plants using reverse osmosis or electrodialysis process have been operated.
Also, many are struggling for the development of membrane to be used for such
processes.
The Central Government-subsidized public works projects concerning the ter-
tiary treatment in FY 1975 (April 1975 ~ March 1976) are only two; Minami-Tama
Sewage Treatment Plant under the Tamagawa Basin-Wide Sewerage Works, Tokyo
Metropolitan Government, and Tone Sewage Treatment Plant under the Jonan
Basin-Wide Sewerage Works, Ibaragi Prefecture.
Since the public waters in Japan have been seriously polluted, the Central
Government and many local governments alike are strongly urged to upgrade the
effluent discharged from sewage treatment plants.
Such being the circumstances, the construction of tertiary treatment facilities
will be pushed forward at most of sewage treatment plants.
Japan is short of the under-ground natural resources, and a narrow, overpopu-
lated country. A population of more than 114 million live on the narrow country.
The national living mainly relies on imports of natural resources which are converted
into industrial products for export.
Some 300 sewage treatment plants installed in the past have all counted on the
biological process using conventional or modified (including conpact types) activated
118 -
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sludge process mainly.
Most of the sewage treatment plants to be constructed from now on will be
adopted conventional activated sludge process as the secondary treatment process.
Herewith, the sewage treatment system for the future should be the design that
is based on the saving of resources and energy, and should also be able to recover
materials contained in the sewage as much as we can.
The studies on the advanced waste treatment in Japan will therefore be guided
and promoted by the Central Government, local governments and private manufac-
tures for the development of new technology meeting the said requirements with
paramount importance attached to the scarcity of resources and energy.
- 119 -
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CHAPTER 2. OUTLINE OF RESEARCH ACTIVITIES ON ADVANCED
WASTE TREATMENT IN PUBLIC WORKS RESEARCH
INSTITUTE, MINISTRY OF CONSTRUCTION 121
120
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2. OUTLINE OF RESEARCH ACTIVITIES ON ADVANCED WASTE TREAT-
MENT IN PUBLIC WORKS RESEARCH INSTITUTE, MINISTRY OF CON-
STRUCTION
Public Works Research Institute, Ministry of Construction, has carried out some
experiments of pilot plant scale at the Shitamachi Sewage Treatment Plant,
Yokosuka, and the Toba Sewage Treatment Plant, Kyoto, and with part of the ex-
isting facilities at the Nishiyama Sewage Treatment Plant, Nagoya.
In these field experiments, engineers and chemists of the Water Pollution
Control Division, Public Works Research Institute and of the Sewerage and Sewage
Purification Bureaus of respective cities have joined efforts for engineering, construc-
tion and operation control of pilot plants or actual facility as well as for the collec-
tion of data. In the meantime, the Water Quality Control Division of the Public
Works Research Institute has undertaken a laboratory study for the purpose of
designing the pilot plant and complementing the data obtained in the field studies.
As reported at the 3rd U.S.-Japan Conference on Sewage Treatment Technolo-
gy held in Tokyo on February, 1974, the members of the Joint Working Group on
Advanced Waste Water Treatment Technology which is composed of the engineers
and chemists from the Ministry of Construction and eight cities have also partici-
pated in the laboratory test of the chemical sedimentation process using lime and
metal salts, and have collected the data.
At the pilot plant located in the Shitamachi Sewage Treatment Plant in
Yokosuka, chemical sedimentation process has been examined in two trains; one
using lime as a coagulant and the other using metal salts. In the lime-using chemical
sedimentation process test, quick-lime has been put to continuous slaking to make
coagulant. In the metal salts-using chemical sedimentation test, various aluminum
salts and iron salts have been tried as coagulants.
The experiments with the pilot plant at the Shitamachi Sewage Treatment
Plant, Yokosuka, have been made for the comparison between various coagulants as
to the efficiency of chemical sedimentation process for removal of phosphorus and
organic matter, study on the method of improving settling efficiency by trying
various coagulants and settling attachment, and tests for thickening and dewatering
of sludge containing coagulants.
Also, the Yokosuka Municipal Government has conducted a study for con-
verting the effluent from the sewage treatment plant into industrial water by using
the effluent of the pilot plant. Recently, this study has been continued by applying
the granular activated carbon adsorption process and reverse osmosis process.
Of the items reported hereunder, those concerning the lime sedimentation pro-
cess and metal salts sedimentation process use the experimental data mainly obtained
from the operation of this pilot plant.
With the pilot plant located at the Toba Sewage Treatment Plant, Kyoto, direct
filtration, granular activated carbon adsorption and breakpoint chlorination have
been studied. At present, a chemical sedimentation tank using metal salts as coagu-
lants is under construction to add to the existing facilities, and the experiment is
scheduled to be started in September this year.
121
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The Toba Sewage Treatment Plant in Kyoto is one of the most largest sewage
treatment plants in Japan, and is featured in that its influent BOD concentration
mixed with supernatant of sludge treatment process is as high as 200 to 350 mg/lit.
The application of the secondary effluent of the Toba sewage treatment plant
to the pilot plant for study purposes is advantageous in that experimental data for
the case where sewage is flowing into the sewage treatment plant at a design rate can
directly be obtained. In general, BOD concentration of the raw sewage running into
the sewage treatment plants are expected to rise more and more in the future in our
country.
In view of these facts, the tertiary pilot plant studies at the Toba Sewage Treat-
ment Plant in Kyoto will have a great significance on the preparation of manual for
engineering, operation and maintenance of the tertiary facilities to be installed at
sewage treatment plants in Japan.
The experiments with the pilot plant at the Toba Sewage Treatment Plant,
Kyoto, have embraced studies on the development and upgrading to a practical level
of instrumentations and automatic control system and for the tertiary treatment
facilities.
The down flow gravity type filter and the chemical sedimentation tank using
metal salts as coagulants which is going to enter upon operation in September this
year are designed to freely control the filtration flow rate of the filter and the in
flow of the chemical sedimentation tank on current signals from the program trans-
mitter.
Also, the composite samplers of the influent and effluent of the filter and
chemical sedimentation tank are designed to operate on the signals from the same
program transmitter.
Of the items reported hereunder, those concerning direct filtration of second-
ary effluent, activated carbon adsorption process, and the regeneration of spent
carbon as well as the breakpoint chlorination process are based on the data acquired
from this pilot plant.
Also, the data from this pilot plant are used in "Automatic Water Quality Meas-
urement for Wastewater Treatment."
The Nishiyama Sewage Treatment Plant, Nagoya, is treating domestic sewage
only with a design sewage flow of 30,000 m3/d.. Raw sewage of 20,000 to 22,000
m3 per day is flowed into the treatment at present.
The plant is composed of two primary sedimentation tanks, two aeration tanks
and three final sedimentation tanks (of which two have been used for this experi-
ment).
As sludge treatment is not carried out in this treatment plant, supernatants
from the sludge treatment facility are not sent into the primary or secondary treat-
ment process.
As regards one train in the treatment plant, a experiment of dosing aluminum
sulphate into the aeration tank has been made. Another train has been used as a
control and operated under conventional activated sludge process. In the Nishiyama
Sewage Treatment Plant, these investigations have been carried out: purification
122
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effects of aluminum sulphate dose into aeration tank, influence of aluminum sul-
phate dose on the organisms and their biological activities in the activated sludge
process, and measurement of sludge productions in the primary sedimentation tanks
and final sedimentation tanks by means of magnetic flowmeters and ultrasonic
sludge concentration meters. It is to be added by the way that one train of auto-
matic backwashing filter comprising 8 compartment vessels is scheduled to be put in
operation in September this year.
Of the items reported hereunder, those concerning "phosphate removal in an
activated sludge facility by alum addition" are based on the data obtained from the
Nishiyama sewage treatment plant, Nagoya. Also, "Study on the treatment and
disposal of sludge" uses data acquired by the investigations at this plant.
Since the beginning of FY 1975, the Public Works Research Institute has been
conducting laboratory studies for nitrofication and denitrofication of municipal
sewage. Especially, the subject of nitrofication study is first stage nitrofication by
using the primary and secondary treatment facilities only of those sewage treatment
plants which are operated on the conventional activated sludge process. If the labor-
atory study is successful, it will be amplified into field experiments at the Nishiyama
Sewage Treatment Plant.
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CHAPTER 3. DIRECT FILTRATION OF SECONDARY EFFLUENT
3.1 Effects on the Filtration and Washing of the Ratio of the Depth of
Anthracite to the Total Depth of Media in the Down-Flow Type
Gravity Dual Media Filter . . . 125
3.2 Effects on the Filtration and Washing of the Difference between Dual
Media and Mixed Media in the Down-Flow Type Gravity Declining
Filtration 126
3.3 Effects of the Sizes of Media in the Down-Flow Gravity Filter on the
Filtration and Washing 127
3.4 Comparison of Filtration Effects between Constant Flow-Rate Filtra-
tion and Declining Flow-Rate Filtration in the Down-Flow Type
Gravity Dual Media Filtration 128
3.5 Comparison of Filtration Effects between the Variable Flow-Rate
Filtration and Declining Flow-Rate Filtration in the Down-Flow Type
Gravity Dual Media Filtration 12g
3.6 Merits and Demerits of Up-Flow Filter 130
124
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3. DIRECT FILTRATION OF SECONDARY EFFLUENT
The Kyoto Pilot Plant now jointly experimented with by the Ministry of
Construction and the Kyoto Municipal City has three down-flow type gravity filters
and one up-flow type filter, each measuring 1.0 m in width, 1.2 m in depth and 3.75
m in height.
Various field studies concerning direct filtration of secondary effluent have
been carried out by using these four pilot filters, and some of the findings were
reported at the 3rd U.S.-Japan Conference on Sewage Treatment Technology held in
Tokyo on February 1974. Later, the pilot filters were modified partly. The data
appearing in this report are obtained from the experiments following the flow
chart shown in Fig. 3.1.
What is changed from the system reported previously is the installation of a
various flow-rate pattern transmitter whose output signal is used to control one of
the down-flow type gravity filter. The Roots pump connected to the effluent pipes
of this filter is feedforward controlled by the current signal from the flow pattern
transmitter, and at the same time feedback controlled by the current signal from the
automatic level gauge on the triangle weir of the effluent measuring tank.
At the end of August this year, two other down-flow type gravity filters were
equipped with a Roots pump and an electric circuit for the same control operation
as above.
As regards the up-flow type filter, which was found as explained later having
troubles with the experiment, a separate test has been made independent of the
down-flow type gravity filters.
3.1 EFFECTS ON THE FILTRATION AND WASHING OF THE RATIO OF
THE DEPTH OF ANTHRACITE TO THE TOTAL DEPTH OF MEDIA IN
THE DOWN-FLOW TYPE GRAVITY DUAL MEDIA FILTER
Part of the results concerning this investigation was reported at the 3rd U.S.-
Japan Conference on Sewage Treatment Technology held in Tokyo on February
1974. Since then, the investigation has progressed, and the following conclusions
are reached.
The effective size and coefficient of uniformity of the media used in the test
are as shown in Table 3.1. The listed media were filled up into the filter No. 1
(type I) and the filter No. 2 (type II) shown in Table 3.2.
The test was conducted on the declining filtration only; both filters got started
at the same time, and when a maximum filtration head loss of 3.0 m was attained,
they were stopped. After the other filters completed filtration, they were washed in
turn, and were restarted to resume filtration test.
a. As shown in Table 3.3, the filtration run length at filtration flow rate of 180
m3/m2 .d. to 420 m3/m2 .d. was about twice as long in type II as in type I. It
was found by means of a head loss meter set in the media that anthracite layer
has a larger capability of holding suspended solids in the secondary effluent
than silica sand layer. It is therefore more advantageous, in the light of the
filtration run length, the larger the thickness of anthracite layer is.
125
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b. Type I and type II are compared in Table 3.4 with respect to filtrate quality
and their removals.
There is no significant difference between the two.
c. The initial head losses of clean media were compared. For a filtration flow rate
of 360 m3/m2. d., for example, the filter arrangement of type I caused an
initial head loss of 54 cm, while the arrangement in type II recorded 36 cm.
The difference was 1.5 in ratio.
d. It was confirmed that with the most suitable expanded bed ratio set at 20%
in the back washing, the back washing rate for type II can be o.71 m3 /m2. min.
as against 0.87 m3 /m2. min. for type I.
The larger the expanded bed ratio becomes, the larger is the difference in back
washing rate between the two.
e. It takes either type 10 to 12 min. to complete back washing.
For either type, surface washing is indispensable.
f. Washing volume/filtrate volume ratio reached 2.3 to 3.2% in case of type I filter
arrangement, but was 1.1 to 2.0% in type II filter arrangement.
It is therefore concluded that the depth of the anthracite layer be maximized.
At any rate, the depth of the anthracite layer should be more than 60% of the total
depth if it is used in the direct filtration down-flow type gravity filter.
The maximum ratio of anthracite layer depth to the total media depth, above
65%, has yet to be studied.
3.2 EFFECTS ON THE FILTRATION AND WASHING OF THE DIFFERENCE
BETWEEN DUAL MEDIA AND MIXED MEDIA IN THE DOWN-FLOW TYPE
GRAVITY DECLINING FILTRATION
Like item 3.1, this was also reported with some results at the 3rd U.S.-Japan
Conference on Sewage Treatment Technology held in Tokyo on February 1974.
Since then, additional experiments have been carried out, and the following
conclusions are reached.
The effective size and coefficient of uniformity of the media used in the
experiments are as given in Table 3.1. The media were filled up in filter No. 2 (type
II) and filter No. 3 (type III). Sizes of the media shown in Table 3.1 were brand new
ones. When preparing the mixed media, they were brought into the filter in several
hauls, and each time back washing was carried to remove fine grains. Thus, the
effective size and coefficient of uniformity were changed accordingly. In type II,
back washing was carried out after the media were filled up totally; namely, fine
grains over the surface of the anthracite layer alone were removed.
a. As shown in Table 3.3, the filtration run length at filtration flow rate of 180
m3/rn2. d. to 420m3/m2 d. tended to become a little longer in type II
arrangement than in type III.
The time history of the readings of the head loss meter set inside the filter in
order to evaluate the capacity of obstruction of suspended solids in the
secondary effluent remained almost common to both types.
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b. The filtrate quality and their removals are compared between type II and type
III in Table 3.4. As is clear, type II was a little better in filtrate quality than
type III.
In type III, the lowermost layer was formed with garnet sand having an effec-
tive size of 0.32 mm., but it was not found the effect of the garnet layer by the
readings of the head loss meter.
c. The initial head losses of clean media were compared. At filtration flow
rates of not exceeding 240m3/m2. d., there was little or no change in the
initial head loss. At 360 m3 /m2. d., type III showed some 3 cm larger loss than
type II.
d. When the most suitable expanded bed ratio of media in the back washing was
set at 20%, both types revealed a back washing flow rate of 0.71 m3/m2 min.
For both types, 10 to 12 min. of back washing time was necessary. The surface
washing was indispensable for both types.
e. In most cases, the washing volume/filtrate volume ratio was a thought smaller
in type II than in type III, which would reflect the fact that type II took a
little longer filtration run length.
It was found that the filtration effect of the mixed media is a little inferior to
the dual media type using the same sizes of anthracite and silica sand. It still remains
obscure whether this is due to poor selection of size or ascribable to the way of
arranging the mixed media layers.
It is conjectured that so long as the direct filtration of secondary effluent is
concerned, there would not be developed any remarkable difference between the
dual media and mixed media even if an improvement is achieved.
3.3 EFFECTS OF THE SIZES OF MEDIA IN THE DOWN-FLOW TYPE GRAVI-
TY FILTER ON THE FILTRATION AND WASHING
After comparative study on filtration performance of three types shown in
Table 3.2, tests were carried out on different media with filters No. 1 and No. 2.
The effective size and coefficient of uniformity of new media are given in Table 3.5.
The constitution of the filter bed of the filters No. 1 and No. 2 in shown in Table
3.6. As regards the declining filtration, comparison study was made with respect to
the difference in the size of media between the filter No. 3 (type III) and filter No. 2
(type IV). The results are as follows.
a. The difference in head loss curve between the two, time variations of filtration
flow rate, and change of filtrate turbidity are shown in Figs. 3.2 and 3.3.
The difference in filtration run length in the declining filtration was larger with
an initial filtration flow rate of 420 m3/m2 d. than 180 m3/m2. d. The de-
crement of the filtration flow rate with time was also larger with 420 m3/m2
d. than 180m3/m2 d.
b. Irrespective of the filtration flow rate, type III showed a little better filtrate
turbidity than type IV as shown in Figs. 3.2 and 3.3. The same held true with
suspended solids, BOD and COD,, as given in Table 3.7 and 3.S., though the
127 -
-------
difference was very small.
c. In type III, the back washing flow rate necessary for attaining a expanded bed
ratio of 20% was 0.7] m3 /m2. min., while type IV required 1.03 m3 /m2. min.
The time necessary for the back washing was almost the same for both.
d. Both types showed no difference in the washing volume/filtrate volume ratio
when operated at a filtration flow rate of 180 m3 /m2. d.
However, type IV showed smaller ratio than type III, the larger the filtration
flow rate became. '
It is therefore concluded that the effective size of anthracite should preferably
be more than 1.6 mm. just as with type IV. This is particularly the case when the
operation is carried out at a high filtration flow rate.
3.4 COMPARISON OF FILTRATION EFFECTS BETWEEN CONSTANT FLOW-
RATE FILTRATION AND DECLINING FLOW-RATE FILTRATION IN THE
DOWN-FLOW TYPE GRAVITY DUAL MEDIA FILTRATION
A comparative study was conducted on type IV (declining flow-rate filtration)
and type V (constant flow-rate filtration). The results are as follows.
a. For the initial filtration flow rate, 180 m3 /m2. d., shown in Fig. 3.4, there was
little or no diffference in the total head loss during filtration.
In the case of declining flow rate filtration, however, the filtration flow-rate
was decreased to 120 m3 /m2. d. when the total head loss reached 3.0 m.
b. For the initial filtration flow-rate, 420 m3 /m2. d., shown in Fig. 3.5, filtration
run length caused a difference of some 12 hrs. It became longer when the
declining flow rate filtration was practised. In the declining flow rate filtration,
however, the declining of filtration flow-rate was noticeable; when the total
head loss was 3.0 m in the constant flow rate filtration, the declining flow rate
filtration had a reduced filtration flow rate of 280 m3 /m2 d.
When the total head loss in the declining flow rate filtration reached 3.0 m, the
filtration flor rate became 240 m3/m2 d. or 57% of the initial filtration flow-
rate.
c. As regards the turbidity, suspended solids, BOD and CODMn listed in Table 3.7
both types showed little or no difference in the filtrate quality. In the case of
direct filtration, the declining flow-rate filtration was not effective in im-
provement of filtrate quality any more than the constant flow-rate filtration.
d. As regards the washing volume/filtrate volume ratio, the constant flow rate filt-
ration was better than the declining flow-rate filtration.
The employment of declining flow rate filtration in the direction of secondary
effluent faces various difficulties in the planning of the filter. Considering the fact
that it is by no means excellent than the constant flow rate filtration, its employment
is quite meaningless.
128 -
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3.5 COMPARISON OF FILTRATION EFFECTS BETWEEN THE VARIABLE
FLOW-RATE FILTRATION AND DECLINING FLOW-RATE FILTRATION
IN THE DOWN-FLOW TYPE GRAVITY DUAL MEDIA FILTRATION
A flow pattern transmitter was installed for the filter No. 1 in order to give a
typical flow pattern of secondary effluent in the sewage treatment plant upon which
to operate the filter. This was type V. A comparison study was made between type
V and type IV in declining flow rate filtration. The flow pattern curve applied to the
testing of type V was based on the measurements taken from the Toba Sewage
Treatment Plant. The flow pattern transmitter generated a pattern for a filtration
flow rate of 300 m3 /m2. d. When the mean filtration flow rate was to be changed
from the above value, the flow pattern was changed in proportion to the deviation.
In the event that the filtration flow-rate was larger than 300 m3/m2. d., the dif-
ference between the maximum and the minimum flow rate became large, while the
difference became smaller if the rate smaller than 300 m3 /m2. d.
The results obtained with the mean filtration flow rates of 180 m3/m2. d., 240
m3 /m2 d., 300 m3 /m2 . d., 360 m3 /m2. d., and 420 m3 /m2. d. are shown in Figs.
3.6, 3.7, 3.8, 3.9 and 3.10, respectively.
The results are as follows.
a. The filtration run length becomes smaller in the variable flow-rate filtration
than in declining flow rate filtration.
The difference however is small in case of the mean filtration flow rate is 180
m3 /m2. d. and 420 m3 /m2. d. For other rates, the difference is remarkable.
Generally, the smaller the inflow of suspended solids into the filter, the smaller
the difference in filtration run length between variable flow-rate filtration and
declining flow rate filtration.
b. The total filtration head loss in the variable flow rate filtration changes with
the media's capacity to detain suspended solids, irrespective of the value of
mean filtration flow rate, the total filtration head loss increases sharply with
increase in the filtration run length. This tendency is more stronger the larger
the mean filtration flow-rate becomes.
c. The filtrate quality in the variable flow rate filtration is a little inferior to that
in the declining flow-rate filtration, though the difference is very small as
shown in Table 3.8. This tendency also applies to those other than turbidity
given in Figs. 3.6 through 3.10.
d. As regards the washing volume/filtrate volume ratio, there is seen little or no
difference between the variable flow rate filtration and declining flow rate
filtration.
All these suggest high feasibility of variable flow-rate filtration for the direct
filtration of the secondary effluent, signifying that the variable flow-rate filtration is
worth further examination. Since the influent of the sewage treatment plant varies
largely at all hours, installation of a regulating reservoir for direct filtration of sec-
ondary effluent would be necessary if constant or declining flow-rate filtration is
practiced at a sewage treatment plant. For this reason, the practice of variable
129
-------
flow-rate filtration within the range of not degrading the filtrate quality is quite an
economical technique for polishing the secondary effluent.
So far this kind of filtration technique has not been taken up seriously. If the
variable flow rate filtration is found to be able to raise a required efficiency, the
polishing of the secondary effluent will be feasible at any sewage treatment plant
economically.
With this in mind, the experiments with the down-flow type gravity filter on
the direct filtration of secondary effluent will be continued with priority given to
the experiments of variable flow-rate filtration.
3.6 MERITS AND DEMERITS OF UP-FLOW FILTER
The up-flow filter has been developed in the Luton Sewage Treatment Plant
and the Blackbird Sewage Treatment Plant in Britain.
This type of filter permits the use of influent directly for the back washing.
Also, it dispenses with post aeration as dissolved oxygen concentration in the filtrate
becomes high.
For this reason, an up-flow filter having a filter area of 1.2 m2 was installed at
the Kyoto Pilot Plant, and has been experimented with. The media size and depth
are shown in Table 3.9. On top of the filter, a grid was placed for the purpose of
suppressing the expansion of bed.
The results of experiments with this filter and considerations are as follows.
a. As shown in Table 3.10, the filtration run length for the maximum filtration
head loss to reach 3.0 m was 20 to 30% longer compared with the declining
flow rate down-flow filter (type II). Whereas the up-flow filter is to be operated
at a constant flow-rate filtration, the up-flow filter under consideration got
directly connected with a influent booster pump as shown in Fig. 3.1, whereby
the filtration flow-rate was reduced during operation. The decrement of the
filtration flow rate was less than one-fifth the declining flow rate down-
flow type filter's. (See Fig. 3.11)
b. The total filtration head loss curve of the up-flow filter under normal operating
conditions is shown in Fig. 3.11.
This filter caused leakage locally in its filter bed, and the increase of the total
head loss was stopped accordingly. Naturally, the suspended solids concentra-
tion in the filtrate rose up. An example of this phenomenon is shown in Fig.
3.12.
This kind of leakage phenomenon happens for certain irrespective of the filtra-
tion flow-rate. The causes are still unknown.
Morigasaki Sewage Treatment Plant, Tokyo, is installed with two up-flow
filters, each having a filter area of 30 m2, which have been used for testing.
These filters also have experienced leakage. The Sewage Bureau of the Tokyo
Metropolitan Government has been pushing forward a survey for the improve-
ment of washing technique and for the feasibility of preventing the bed leakage
by limiting the total filtration head loss to 2.8 m.
c. As regards the turbidity, suspended solids, BOD and CODMn listed in Table
- 130
-------
3.11. Up-flow filter showed little or no difference as compared with down-flow
declining filter in the filtrate quality.
d. In the up-flow filter, the bed is put to cleaning by air agitation and back wash-
ing in combination. The experiments with the up-flow filter in the Kyoto Pilot
Plant disclosed that the cleaning is not sufficient if air agitation and back
washing alone are counted upon. For this reason, the following method was
tried.
Draining of filter bed - Air agitation (4 min.) - Rest (2 min.) - Air agitation
(4 min.) - Water pulsating washing (20 sec.) - Rest (1 min.) - (10 repetitions
of water pulsating washing and rest in combination) - Water back washing (10
min.) - Water level depression in filter bed - Water back washing (10 min.) -
Start of filtration
Although the above cleaning procedure has been tried, it still is uncertain
whether the media arrangement is warrantable to always keep the filter bed
clean and to prevent leakage phenomenon. There is a fear of causing a great
quantity of overflow of media from the washed water trough as the entire filter
bed comes afloat in the pressurized water unless the filter bed is monitored all
the way from the beginning of water pulsating washing. In the experiments
with the up-flow filter at the Kyoto .Pilot Plant, less importance was attached
to the flotation of the filter bed, and there has been experienced overflow of a
great amount of media from the washed water trough several times.
e. At the Morigasaki Sewage Treatment Plant, Tokyo, investigations have been
made as to the cleaning method of up-flow filter bed.
As a result, the following technique is proposed as best.
Draining of filter bed — Air agitation (6 min.) and water back washing (10
min.) in combination (the final four min. for water back washing only) — Air
agitation (6 min.) and water back washing (12 min.) in combination (the final
six min. for water back washing only) — Rest (5 min.) — Start-up of filtration
It is claimed that the rest prepared in the final stage is indispensable for the
stabilization of media and consequently for the prevention of leakage
phenomenon.
f. The same cleaning method as in the Morigasaki Sewage Treatment Plant has not
been tried in the Kyoto Pilot Plant as the combined use of air agitation and
water back washing necessitates a large scale modification of electric control
circuit used for the up-flow filter.
As the past experiments suggests, it is evident that sudden application of'air
agitation and water back washing" can cause a great deal of overflow of media
from the washed water trough as the media are buoyed.
The overflow trouble due to water pulsating washing or back washing may be
peculiar only to small-scale filters like one in the Kyoto Pilot Plant. In a large
scale up-flow filter, the media may not be buoyed uniformly at the time of
water washing. Once in a while, the Morigasaki Sewage Treatment Plant,
Tokyo, has been processing only a limited quantity of influent, and the con-
centration of suspended solids in the secondary effluent is less than 10 mg/lit..
131
-------
On the other hand, the concentration of suspended solids in the secondary
effluent of the Toba Sewage Treatment Plant is Kyoto is as high as 25 to 35
mg/lit. Some fear that if secondary effluent containing high ratio of suspended
solids like this is directly filtered, the media separation would become difficult
because of adhesive power developed by suspended solids between media
particles.
These doubts will be clarified by further investigations.
The up-flow filter in Kyoto Pilot Plant requires some 1 hr. for washing of filter
bed. On the other hand, the Morigasaki's is some 40 min. Then, the down-flow
filter requires less than 20 min. even if surface washing and back washing are
carried out in combination.
The washing water volume for the up-flow type filter is about 2.2 to 3 times as
large as that for the down-flow type. It is evident that the down-flow filter is
superior to up-flow filter when viewed from the washing volume/filtrate
volume ratio.
As discussed in the foregoing, the up-flow filter has various problems to solve
before it will be put to practice. For the purpose of direct filtration of seconda-
ry effluent, further investigations are necessary.
The authors have continued experiments with the up-flow filter believing in the
fact that it permits the use of influent for washing purposes, which is hardly
expected of the down-flow filter. The authors will continue efforts for refining
the up-flow filter until it can stand practical use.
132 -
-------
Table 3.1 Media Size Using Experiment of Down
Flow Type Gravity Filters
Media
Anthercite coal
Silica sand
Garnnet sand
Effective size (mm)
0.95
0.64
0.32
Uniformity coefficient
1.48
1.50
2.16
133
-------
Table 3.2 Media Depth Using Experiment of Down Flow
Type Gravity Filters (Type I, II and III)
of experiment
v-
Kinds
Type I
No. 1
Type II
No. 2
Type III
No. 3
Anthercite coal
1 50 (mm)
625 (mm)
625 (mm)
Silica sand
850
375 (mm)
300
Gamnet sand
75
Total
1,000
1,000
1,000
Type of filtration
Declining
Declining
Declining
134
-------
Table 3.3 Operational Data of Filtration Run Length of Down Flow Pilot Filters
(Max. Total Head Loss 3.0 meter)
(hrs)
Types of
experiment
Type I
Type II
Type III
Used
filter
Filter
No. 1
Filter
No. 2
Filter
No. 3
Items
Max.
Min.
Ave.
Max.
Min.
Ave.
Max.
Min.
Ave.
Flow-rate (m3/m2-d)
180
62:00
6:33
32:93
125:25
11:25
71:55
129:00
31:00
69:23
240
54:75
9:75
28:96
101:50
7:50
53:17
94:00
22:25
58:49
300
50:30
9:75
20:92
125:25
21:75
48:07
113:50
23:25
40:00
360
36:25
4:00
21:40
65:75
4:50
38:80
57:75
7:50
33:32
420
47:67
7:00
20:33
100:00
12:50
50:00
94:00
9:15
37:70
- 135
-------
Table 3.4 Operational Data of Down Flow Pilot Filters (Water Quality of Influents and Effluents and Their Removals)
^\\^~~^ __Typeof experiment
^\"\^_JJse^^
Items ^-^™fr^^
Turbidity
Sus. solids
BOD
CODMn
Cone.
(mg/C)
Inf.
Eff.
Removal (%)
Cone.
(mg/ej
Inf.
Eff.
Removal (%)
Cone.
(mg/e)
Inf.
Eff.
Removal (%)
Cone.
(rng/2)
Inf.
Eff.
Removal (%)
Type I
Filter No. 1
180
8.4
2.9
65.5
13.3
4.0
69.9
22.8
7.9
65.4
17.0
14.5
14.7
240
6.6
2.3
65.2
12.8
3.7
71.1
19.4
4.8
75.3
15.1
11.8
21.9
300
6.9
2.5
63.8
•11.5
3.4
70.4
21.2
4.9
76.9
14.5
12.1
16.6
360
7.8
3.1
60.0
14.6
4.5
69.2
27.2
6.8
75.0
16.1
12.5
22.4
420
7.8
5.5
29.5
15.0
5.9
60.7
20.6
7.2
65.0
15.0
12.6
16.0
Type II
Filter No. 2
180
8.0
3.7
53.8
12.9
5.2
59.7
22.9
6.9
69.9
17.3
14.5
16.2
240
6.5
2.8
56.9
12.5
3.2
74.4
17.9
5.3
70.4
15.0
12.1
19.3
300
6.9
2.9
60.0
12.0
4.4
63.3
21.8
6.0
72.5
15.7
12.1
22.9
360
8.4
3.2
64.4
14.0
3.7
73.5
25.3
7.6
70.0
16.2
13.0
19.8
420
8.1
5.3
34.6
12.7
6.0
52.8
17.1
7.4
56.7
15.3
12.9
15.7
Type III
Filter No. 3
180
7.9
4.1
48.1
13.0
4.0
69.2
22.8
7.2
68.4
16.7
15.8
5.4
240
6.6
2.8
57.6
12.5
3.6
71.2
17.6
4.6
73.9
15.1
12.8
15.2
300
6.8
3.1
54.4
12.1
4.5
62.8
23.8
7.2
69.7
15.7
12.9
17.8
360
7.9
3.2
59.5
12.8
4.3
66.4
23.0
7.9
65.7
15.9
12.9
18.9
420
7.7
5.8
24.8
13.2
5.6
57.6
16.8
6.7
60.1
13.9
13.1
5.8
-------
Table 3.5 Media Size Using Experiment of Down Flow Type Filters
Media
Anthercite coal
Silica sand
Effective size (mm)
1.62
0.605
Uniformity coefficient
1.327
1.256
- 137
-------
Table 3.6 Media Depth Using Experiment of Down Flow Type Gravity Filters
(Type IV, Type V and Type VI)
^:^\-~~^^Type of experiment
^---_ __Used fijter
Kinds of media — "^"^^-^__
Anthercite coal
Silica sand
Total
Type of filtration
Type IV
No. 2
625 (mm)
325
1,000
Declining
Type V
No. 1
625 (mm)
325
1,000
Constant
Type VI
No. 1
625 (mm)
325
1,000
Variable
- 138 -
-------
Table 3.7 Operational Data of Down Flow Pilot Filters
(Water Quality of Influent and Effluent and Their Removals)
xj>^^^^ Types of Experiment
\^\ Used Filter
Items \Flow-rate(rn3/m2-d)
Turbidity
Sus. Solids
BOD
CODMn
Cone.
(mg/1)
Inf.
Eff.
Removal (%)
Cone.
(mg/D
Inf.
Eff.
Removal (%)
Cone.
, (mg/1)
Inf.
Eff.
Removal (%)
Cone. Inf.
(mg/1) | Eff.
Removal (%)
Remarks
TypeV
Filter No. 1
180
3.9
2.1
46.2
6.4
2.5
60.9
14.9
6.1
59.1
15.7
14.6
7.0
240
4.3
3.0
30.2
4.5
4.0
11.1
6.0
4.4
26.7
17.9
17.4
2.8
300
2.7
2.2
18.5
3.0
3.0
0
6.0
2.8
53.3
14.0
(16.2)
360
-
_
_
_
420
2.8
2.1
25.0
3.2
2.1
34.4
20.1
12.6
37.3
17.7
16.3
7.9
Constant Flow-rate
Type IV
Filter No. 2
180
3.9
2.5
35.9
6.4
2.7
57.8
14.9
4.6
69.1
15.7
14.3
8.9
240
4.3
3.1
27.9
4.5
3.8
15.6
6.0
4.5
25.0
17.9
16.2
9.5
300
2.7
2.5
7.4
3.0
(3.1)
6.0
3.0
50.0
14.0
(16.7)
360
-
-
~
-
420
2.8
2.3
17.9
3.2
2.5
21.9
20.1
13.1
34.8
17.7
15.6
11.9
Declining Flow-rate
Type III
Filter No. 3
180
3.9
2.6
33.3
6.4
3.0
53.1
14.9
5.9
60.4
15.7
14.2
9.6
240
4.3
3.2
25.6
4.5
4.1
8.9
6.0
5.9
1.7
17.9
16.8
6.2
300
2.7
2.6
3.7
3.0
2.6
13.3
6.0
3.5
41.7
14.0
(19.7)
360
-
_
:
-
420
2.8
2.3
17.9
3.2
2.2
31.3
20.1
12.9
35.8
17.7
16.9
4.5
Declining Flow-rate
-------
Table 3.8 Operational Data of Down Flow Pilot Filter
(Water Quality of Influent and Effluent and Their Removals)
N^\~~^^^ Types of Experiment
x\
Used Filter
Items ^\J;l°w-rate (m3/m2-d)
Turbidity
Sus. Solids
BOD
CODMn
Cone.
(mg/1)
Inf.
Eff.
Removal (%)
Cone.
(mg/1)
Inf.
Eff.
Removal (%)
Cone.
(mg/1)
Inf.
Eff.
Removal (%)
Cone.
(mg/1)
Inf.
Eff.
Removal (%)
Remarks
Type VI
Miter No. 1
180
5.4
3.5
35.2
7.5
3.9
48.0
19.3
6.0
68.9
25.0
22.7
9.2
240
5.6
4.2
25.0
7.1
5.2
26.8
12.7
6.5
48.8
21.8
17.7
18.8
300
4.4
2.7
38.6
5.5
4.0
27.3
20.7
10.0
51.7
20.7
16.4
20.8
360
8.2
5.3
35.4
9.8
6.6
32.7
17.5
7.3
58.3
20.5
16.7
18.5
420
6.2
4.3
30.7
9.0
7.5
16.7
16.5
9.4
43.0
24.2
22.7
6.2
Variable Flow-rate
Type IV
Filter No. 2
180
5.4
3.5
35.2
7.5
3.8
49.3
19.4
5.9
69.6
24 6
21.8
11.4
240
5.6
4.2
25.0
7.1
4.8
32.4
12.7
5.8
54.3
21.8
18.5
15.1
300
4.4
3.1
29.6
5.5
4.2
23.6
20.7
9.5
54.1
20.7
18.4
11.1
360
8.2
5.1
37.8
9.9
6.0
39.4
17.6
7.6
56.8
20.3
17.2
15.3
420
6.2
4.5
27.4
9.0
6.5
27.8
16.5
8.9
46.1
24.2
(27.3)
Declining Flow-rate
- ' 1
Type HI
Filter No. 3
180
5.2
3.5
32.7
7.5
3.5
53.3
20.1
5.8
71.1
24.9
20.7
16.9
240
5.6
4.0
28.6
7.1
4.1
42.3
12.7
5.7
55.1
21.8
18.2
16.5
300
4.4
2.8
36.4
5.5
3.7
32.7
20.7
9.6
53.6
20.7
17.1
17.4
360
8.2
4.9
40.2
9.7
6.3
35.1
17.5
6.7
61.7
20.4
16.5
19.1
420
6.2
4.1
33.9
9.0
6.4
28.9
16.5
9.2
44.2
24.2
23.7
2.1
Declining Flow-rate
-p.
o
-------
Table 3.9 Media Size and Depth for Up-flow Filter
^"^^^^ Size and depth
Items -\^^
Filter media (Silica sand)
Sand for media support
Gravel for media support
Media size
Effective size
(mm)
1.16
2.11
Uniformity
coefficient
1.33
1.31
2~ 3
10-15
20-30
Depth (mm)
1,550
300
250
100
- 141 -
-------
Table 3.10 Operational Data of Filtration Run Length of
Both Dp-flow Filter and Down Flow Filter
(his.)
Types of
Experiment
Up-flow Filter
Down-flow Filter
(Type II)
Filter
Filter
No. 4
Filter
No. 2
Items
Max.
Min.
Ave.
Max.
Min.
Ave.
Flow-rate (m3/m2-d)
180
131.00
54.25
91.45
125.25
11.25
71.55
240
105.00
20.50
68.80
101.50
7.50
53.17
300
124.45
20.00
55.90
125.25
21.75
48.07
360
55.50
23.50
48.50
65.75
4.50
38.80
- 142 -
-------
Table 3.11 Comparison of Filtrate Quality of Both Dp-Flow Filter and Down-Flow Filter
^^JTyr^offilter^
\ \ Filter nui
Xlnitial
Turbidity
Sus. solids
BOD
CODMn
Cone.
(mg/fi)
Tiber
m'-d)
Inf.
Eff.
Removal (%)
Cone.
(mg/fi)
Inf.
Eff.
Removal (%)
Cone.
(mg/fi)
Inf.
Eff.
Removal (%)
Cone.
(mg/fi)
Enf.
Eff.
Removal (%)
Up-flow filter
No. 4
180
8.0
3.4
57.5
13.0
4.0
69.2
22.8
6.8
70.2
16.7
15.3
8.4
240
6.1
3.4
44.3
11.4
4.0
64.9
17.8
5.7
70.0
14.5
12.9
11.0
300
6.9
3.2
53.6
12.2
5.0
59.0
23.4
6.8
70.9
16.0
13.1
18.1
360
8.3
3.1
62.7
13.0
4.6
64.6
21.4
6.8
31.8
14.0
12.7
9.3
Down-flow filter (Controlled)
No. 2
180
8.0
3.7
53.8
12.9
5.2
59.7
22.9
6.9
69.9
17.3
14.5
16.2
240
6.5
2.8
56.9
12.5
3.2
74.4
17.9
5.3
70.4
15.0
12.1
19.3
300
6.9
2.9
60.0 '
12.0
4.4
63.3
21.8
6.0
72.5
15.7
12.1
22.9
360
8.4
3.2
64.4
14.0
3.7
73.5
25.3
7.6
70.0
16.2
13.0
19.8
420
8.1
5.3
34.6
12.7
6.0
52.8
17.1
7.4
56.7
15.3
12.9
15.7
- 143
-------
Coagulant Tank
Final Sedimentation Tank
Down Flow Type Gravity Filter
Filter No.l
r
Filter N
V
h
Media .
i
I
i .
.t
Filter No.3
Media
Filtered Water
Line No.l
Rutz
PJPump
Flow Measuring
Tank No.2
Surge Tank
Upflow Filter
Grid
Media
FEtered
Water
Line
No.3
Flow Measuring
Tank No.4
~rr\ Debubbler
Washed Water
Flow Measuring Tank
Outflow line
to-
Filtered Water Storage Tank
-tx-
Effluent
-- Effluent
Fig. 3.1 Flow Chart of Pilot Filtration Facility, Kyoto Pilot Plant
-------
3 -
6-
5-
V 4-
A
•
X
Filtration Flow-rate Variation of Type IV
Filtration Flow-rate Variation of Type III
Total Head Loss Variation of Type IV
Total Head Loss Variation of Type III
Turbidity of Influent
Turbidity of Effluent (Type IV)
Turbidity of Effluent (Type III)
Type IV • See Table 3.5 and 3.6
Type III: See Table 3.1 and 3.2
1 -
32 36 40 44 48 52 56
Run Length (hrs)
60
64
68 72
76
80 84
-i
92
Fig. 3.2 Effect of Media Size in Down-flow Declining Dual Media Filter on Total Head Loss, Flow Rate, and
Turbidity Variations
(Initial Filtration Flow-rate 180m3/m2 d)
-------
1 -
0 J
6 -
-34 -
•
X
Filtration Flow-rate Variation of Type IV
Filtration Flow-rate Variation of Type III
Total Head Loss Variation of Type IV
Total Head Loss Variation of Type III
Turbidity of Influent
Turbidity of Effluent (Type IV)
Turbidity of Effluent (Type III)
Type IV : See Table 3.5 and 3.6
Type III: See Table 3.1 and 3.2
12 16 20 24 28 32 36 40 44
Run-Length (hrs)
48
52 56
60
64 68
72
Fig. 3.3 Effect of Media Size in Down-flow Declining Dual Media Filter on Total Head Loss, Flow Rate, and
Turbidity Variations
(Initial Filtration Flow-rate 420 m3 /m2 • d)
-7
6
-5
- 4 .0
^
•3
-------
6-1
5-
Constant Filtration Flow-rate
Declining Filtration Flow-rate Variation
Constant Filtration Total Head Loss Variation
• • Declining Filtration Total Head Loss Variation
•A Turbidity of Influent
• Turbidity of Effluent (Constant Filtration)
X Turbidity of Effluent (Declining Filtration)
X
13
12
16 20
24 28
32
36
64
72
40 44 48 52 56 60
Run Length (hrs)
Fig. 3.4 Comparison of Constant Flow-rate and Declining Flow-rate Filtrations on Total Head Loss, Flow-rate,
and Turbidity Variations in Down-flow Dual Media Filters
(Initial Filtration Flow-rate 180 m3/rn2- d)
76 80 84 88 92
•9
•8
7
6
5
• 4 £•
3 H
2
1
0
-------
-pi
CO
3-
6 -
s •
4 -
Constant Filtration Flow-rate
Declining Filtration Flow-rate Variation
Constant Filtration Total Head Loss Variation
• • Declining Filtration Total Head Loss Variation
^ Turbidity of Influent
• Turbidity of Effluent (Constant Filtration)
X Turbidity of Hffluent (Declining Filtration)
,*_
53
_o
LL.
1-
0J
—p-
12
16 20
24
28
32
36 40 44
Run Length (hrs)
48
52
56 60 64 68 72
76
Fig. 3.5
Comparison of Constant Flow-rate and Declining Flow-rate Filtrations on Total Head Loss, Flow-rate,
and Turbidity Variations in Down-flow Dual Media Filters
(Initial Filtration Flow-rate 420 m3 /m2 • d)
3
2
1
0
-------
3-
6-
5 -
E 4-
Flow-rate Pattern of Variable Filter
Flow-rate Variation of Declining Filter
Total Head Loss Variation of Variable Filter
Total Head Loss Variation of Declining Filter
Turbidity of Influent
Turbidity of Effluent (Variable Filter)
Turbidity of Effluent (Declining Filter)
6
5
O1
~o£
4 £
H
L0
12
16 20 24 28 32
36 40 44 48 52 56 60 64 68 72 76 80 84
Run Length (hrs)
Fig. 3.6 Comparison of Variable Flow-rate and Declining Flow-rate on Flow-rate, Total Head Loss and Turbidity
Variations in Down-flow Dual Media Filters
Average Flow-rate of Variable Filter: Approx. 180m3/m2- d
Initial Flow-rate of Declining Filter: 180 m3/m2- d
88
-------
en
o
Flow-rate Pattern of Variable Filter
Flow-rate Variation of Declining Filter
Total Head Loss Variation of Variable Filter
Total Head Loss Variation of Declining Filter
Turbidity of Influent
Turbidity of Effluent (Variable Filter)/
Turbidity of Effluent (Declining / ,-' \
H 1 -
1 .
0J
16
20 24
32 36
40 44
—i—
48
52
56 60 64 68 72
76 80
—i—
84
Run Length (hrs)
Fig. 3.7 Comparison of Variable Flow-rate and Declining Flow-rate on Flow-rate, Total Head Loss and Turbidity
Variations in Down-flow Dual Media Filters
f Average Flow-rate of Variable Filter: Approx. 240 m3 /m2 • d 1
[initial Flow-rate of Declining Filter: 240 m3/m2 • d \
92
12
11
10
-9
-8
-7
-6
-4
•3
2
1
0
-------
3H 6-1
5 •
E4 -
o
o
Plow-rate Pattern of Variable Filter
Flow-rate Variation of Declining Filter
Total Head Loss Variation of Variable Filter
Total Head Loss Variation of Declining Filter
Turbidity of Influent
Turbidity of Effluent (Variable Filter)
Turbidity of Effluent (Declining Filter)
16 20 24 28
—i—
32
36 40 44
Run Length (hrs)
48 52
56 60
64
12
Fig. 3.8 Comparison of Variable Flow-rate and Declining Flow-rate on Flow-rate, Total Head Loss and Turbidity
Variations in Down-flow Dual Media Filters
T Average Flow-rate of Variable Filter: Approx. 300 m3/m2 • d
[initial Flow-rate of Declining Filter: 300 m3/m2 • d
• 3
2
1
0
-------
On
INJ
0J
How-rate Pattern of Variable Filter
Flow-rate Variation of Declining Filter
Total Head Loss Variation of Variable Filter
Total Head Loss Variation of Declining Filter
Turbidity of Influent
Turbidity of Effluent (Variable Filter)
Turbidity of Effluent (Declining Filter)
32 36 40
Run Length (his)
44
48
52 56 60 64 68 72
76
Fig. 3.9 Comparison of Variable Flow-rate and Declining Flow-rate on Flow-rate, Total Head Loss and Turbidity
Variations in Down-flow Dual Media Filters
[ Average Flow-rate of Variable Filter: Approx. 360 m3/m2 -d
[ Initial Flow-rate of Declining Filter: 360 m3/m2 • d
-------
3-
6 -
Flow-rate Pattern of Variable Filter
Flow-rate Variation of Declining Filter
Total Head Loss Variation of Variable Filter
Tola] Head Loss Variation of Declining Filter
<* Turbidity of Influent
• Turbidity of Effluent (Variable Filter)
x Turbidity of Effluent (Declining Filter)
16
20 24
44
48
52 56
64 68
8 32 36 40
Run Length (lirs)
Fig. 3.10 Comparison of Variable Flow-rate and Declining Flow-rate on Flow-rate, Total Head Loss and Turbidity
Variations in Down-flow Dual Media Filters
^Average Flow-rate of Variable Filter: Approx. 420 m3/m2 • d
[initial Flow-rate of Declining Filter: 420 m3/m2 • d
-------
Cn
1-
0J
40 44 48
Run Length (hrs)
Fig. 3.11 Examples of Normal Operations of Dp-flow Filters
84 88
92
-------
3 •
6-
5 -
•04
1=
•3-
Total Head Loss
Filtration Flow-rate
\ -
0 Initial Flow-rate 180m3/m2-d
© Initial Flow-rate 240m3/m2-d
(3) Initial Flow-rate 300m3/m2-d
0 Initial Flow-rate 360m3/m2-d
©
12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 80 84
Run Length (hrs)
Fig. 3.12 Examples of Suspended Solids Leakage in Sand Beds at Up-flaw Filter Test Operations
92
96
-------
CHAPTER 4. METAL SALTS PRECIPITATION
4.1 Estimate of Concentration of Dissolved Phosphorus in Effluent and
Removal of Dissolved Phosphorus 157
4.1.1 Form of Phosphorus Used for Determination of Mole Ratio 157
4.1.2 Relationship between Mole Ratio, Dissolved Phosphorus in Effluent,
and Residual Dissolved Phosphorus 157
4.1.3 Summary 160
4.2 Comparison of Coagulant Constant Feed and Mole Ratio Control 161
4.2.1 Where Influent Flow is Set Constant 161
4.2.2 Where Influent Flow is Changeable 162
4.2.3 Considerations 164
4.3 Results of Pilot Plant Examinations 166
4.3.1 Results of Wastewater Treatment 166
4.3.2 Results of Sludge Dewatering . ... 167
4.4 Development of High-Rate Flocculation-Sedimentation System —
An Example of Advanced Waste Treatment Technical Development
at a Private Company — . . 169
4.4.1 Principles and Features of the Installation 169
4.4.2 Pilot Plant Experiment at the Senda Sewage Treatment
Plant, Hiroshima City 170
4.4.3 Pilot Plant Experiment at the Shinhama Sewage Treatment
Plant, Fukuyama City .
- 156 -
-------
4. METAL SALTS PRECIPITATIQN
4.1 ESTIMATE OF CONCENTRATION OF DISSOLVED PHOSPHORUS IN
EFFLUENT AND REMOVAL OF DISSOLVED PHOSPHORUS
The Joint Working Group on Advanced Wastewater Treatment Technology
conducted jar tests in the winter of 1974 on the phosphorus removal by metal
salts precipitation. The coagulants used were alum (A12(SO4)3 • 18H2O), ferric
chloride (FeCl3, 26.2% Fe solution), and MICS (a mixture of alum and ferric sul-
fate, solution of A12O3 (5.42%) and Fe2O3 (2.0%) available on market here in
Japan.
The samples were influent to the primary settler and the secondary effluent,
taken around 9:00 a.m. from 14 to 15 typical sewage treatment plants in Japan.
4.1.1 FORM OF PHOSPHORUS USED FOR DETERMINATION OF MOLE
RATIO
In the test the mole ratios of metal salts to be dosed were set at 0.5, 1.0,
1.5, 2.0, 2.5 and 3.0 with the phosphorus (P: total phosphorous by persulfate
digestion) in influent as a basis (e.g., Al/P, Fe/P, (Al +Fe)/P). No particular pH
control was carried out.
Fig. 4.1 shows the relationship between phosphorus in influent and residual
dissolved phosphorus (P-D, filtered through 1.2 n millipore, persulfate digestion)
for mole ratios of 1.0, 2.0, and 3.0 based on phosphorus in influent. Fig. 4.2
shows the relationship between the dissolved phosphorus in influent and residual
dissolved phosphorus for mole ratios of 1.0, 2.0, and 3.0 based on dissolved phos-
phorus in influent. Fig. 4.2 provides better correlation than Fig. 4.1 when com-
pard on the same mole ratio.
It is hence inferred that insoluble phosphorus in influent does not react upon
Al dosed.
Figs 4.1 and 4.2 show only the results of alum treatment, but the results of
treatments with ferric chloride and MICS also showed the same tendency.
For this reason, the discussions hereunder use the mole ratios based on the
dissolved phosphorus in influent.
4.1.2 RELATIONSHIP BETWEEN MOLE RATIO, DISSOLVED PHOSPHORUS
IN INFLUENT, AND RESIDUAL DISSOLVED PHOSPHORUS
As shown in Fig. 4.2, the concentration of dissolved phosphorus in influent
and residual dissolved phosphorus are expressed by a straight regression line when
the mole ratio obtained based on dissolved phosphorus concentration of influent
is fixed at a constant value.
It is assumed that the relationship between the concentration of influent dis-
solved phosphorus (P-Dj ) and the concentration of effluent dissolved phosphorus
(P—D£) is given by the following formula.
(P-DE) = ax(P-Dt) + b (1)
Mole ratio: constant
(P-DE), (P-Dj): inmg.P/lit.
a, b: constants
Then regression line is determined for each mole ratio, and a, b, and
157
-------
standard deviation of (P-D£) is calculated as shown in Table 4.1.
While the calculation for influent to the primary settler is made up to a mole
ratio of 4, the calculation for the secondary effluent is up to a mole ratio of 3.
This is due to the following reason.
In this test, with the concentration of phosphorus in the influent as a basis
for determination of mole ratio, the mole ratios were increased up to 3 at an
interval of 0.5. But it was found that the mole ratio can better be determined
based on the concentration of dissolved phosphorus as stated in 1—2, and the
results of the test were revised with the mole ratios determined according to the
concentration of dissolved phosphorus.
On the other hand, the ratio of insoluble phosphorus in influent to phos-
phorus was larger in the influent to the primary settler; almost all results showed
that when the mole ratio was 3.0 as calculated based on phosphorus in influent to
the primary settler, the mole ratio calculated on the bais of dissolved phosphorus
became more than 4.0.
In the case of secondary effluent, the ratio of insoluble phosphorus was com-
paratively small, so there was rarely the case that the mole ratio based on dis-
solved phosphorus was beyond 3.5. This is also evidenced by the fact that the
secondary effluent show better correlations in Fig. 4.1.
The range of the concentration of dissolved phosphorus in the inlfuent used
in the experiment was almost the same for ferric chloride, MICS and alum. Thus
the range of the concentration of dissolved phosphorus in influent in which the
computation results shown in Talbe 4.1 can be applied seems to be preferably 1.5
to 10 mg.P/lit. for influent to the primary settler and 0.5 to 3 mg.P/lit. for the
secondary effluent. From Eq. (1), the removal of dissolved phosphorus (Rp_D)
for the same mole ratio can be expressed as follows.
(RP_D)(%) = (1 -((p " ffix 100
= (l-a )x 100 (2)
(P-D,)'
Eq. (2) suggests that the mole ratio calculated from dissolved phosphorus in
influent does not univocally determine the removal (RD „ ). but that in the same
K — U
mole ratio the removal increases with increase in the concentration of dissolved
phosphorus in influent as b is larger than O (see Table 1).
By way of example, Fig. 4.3 shows the relationship between the removal of
dissolved phosphorus and the concentration of dissolved phosphorus with respect
to the case where the influent to the primary settler is treated with alum.
In order to compare the performance of three coagulants, the concentrations
of dissolved phosphorus in the effluent of influent to the primary settler treated
with each coagulant were determined with a, and b in Table 4.1. The values used
for the calculation are as follows. The mole ratios are 0.5, 1, 1.5, 2, 2.5, 3, 3.5,
and 4.0, and the concentration of dissolved phosphorus in influent to the primary
settler are 2, 4, 6, and 8 mg.P/lit. The results were as follows.
The concentrations of dissolved phosphorus after treatment with ferric
chloride and MICS were respectively 1.61 times (0.94 to 9.41) and 1.05 times
- 158 -
-------
(0.57—3.85) on the average as large as that after treatment with alum; namely,
ferric chloride was inferior in removal of phosphorus to the other two.
One of the causes conceivable is pH after addition of coagulant. As already
touched upon, the experiment under discussion was conducted without pH adjust-
meht. As a consequence, as against the average pH value of raw sewage being 7.4
(6.6-8.1), the pH value after treatment with a mole ratio of 3, for example, was
6.8 on the average for all three coagulants — alum 6.8 (6.3~7.3), ferric chloride
6.8 (6.5-7.2) and MICS 6.8 (6.3-7.4). It is said that the optimum pH value for
removal of phosphorus is 5.5 to 6.5 for alum and 4.5 to 5.0 for ferric chloride*.
The deviation of the average pH value, 6.8, from the optimum pH value after
treatment at a mole ratio of 3 was 1.8 to 2.3 for ferric chloride and 0.3 to 1.3
for alum, and was greater in ferric chloride treatment than in alum treatment. It is
therefore considered that the treatment with alum will lower residual dissolved
phosphorus concentration more than with ferric chloride. The same tendency was
observed with the secondary effluent.
With the values in Table 4.1 taken as a reference, the relationship between
the more ratio and dissolved phosphorus concentration obtained after treatment
of raw sewage with alum is shown in Fig. 4.4. According to Fig. 4.4 , the dif-
ference of the dissolved phosphorus concentration after treatment due to dif-
ference in the dissolved phosphorus concentrattion in influent decreases with in-
crease in mole ratio, attains zero at a certain mole ratio (2.5 in this case), and
then turns reversely.
The mole ratio at which the dissolved phosphorus in the effluent was held
constnat irrespective of the concentration of dissolved phosphorus in the influent
to the primary settler was 2.5 for alum, 3.4 for ferric chloride and 2.9 for MICS.
The same tendency was observed with the secondary effluent.
The removability of dissolved phosphorus in raw sewage and secondary
effluent is compared in the following way. Dissolved phosphorus concentration in
influent was taken as 2 and 3 mg./lit. which lie in the range in which Table 4.1
can be applied common to influent to the primary settler and secondary effluent,
and as 0.5, 1, 1.5, 2, 2.5 and 3 in terms of mole ratio, and the corresponding
residual total dissolved phosphorus concentrations were calculated. Then the
calculation showed that the ratios of dissolved phosphorus in the secondary
effluent to that in the raw sewage treated with alum, ferric chloride and MICS
were 1.25 (1.06-1.50), 1.01 (0.78-1.16) and 1.06 (0.94-1.21) on the average
respectively. From this, it is inferred that the secondary effluent is a little easier to
remove phosphorus as compared with raw sewage, a little though the difference may
be.
The relationship between a and b in Table 1 and mole ratios is shown in
Fig.s 4.5 and 4.6 with respect to the treatment of raw sewage with alum.
In other conditions, reltionships between a and b in Table 4.1 and mole
ratios are similar to Fig. 4.5, and 4.6.
If a and b can be expressed by the following formula (Eq. 3) according to
* U.S.E.P.A. Process Design Manual for Phosphorus Removal, Oct. 1971.
159
-------
Figs. 4.5 and 4.6, then the substitution of Eq. (3) for Eqs. (1) and (2) will
establish functions in terms of the mole ratio to phosphorus of dosed metal salts
obtained based on the dissolved phosphorus concentration in influent as also of
dissolved phosphorus concentration in influent, which can show residual dissolved
phosphorus concentration and removal of dissolved phosphorus in the metal salts
precipitation.
a = f(MR), b - g(MR) (3)
MR is mole ratio based on dissolved phosphorus in influent.
This time, however, we are not yet to refine the curves in Figs. 5 and 6 into
such a function, and we will continue further study in this respect.
Tables 4.2, and 4.3 show the relationships between the dosages of alum, ferric
chloride, and MICS and mole ratios necessary for attaining the target dissolved
phosphorus concentrations in effluent of 0.1, 0.2, 0.3, 0.5, and 1.0 mg.P/1, and
the target removal of dissolved phosphorus of 98, 95, 90, 85, and 80%, and dis-
solved phosphorus in influent.
4.1.3 SUMMARY
i) In case wastewater is treated with metal salts, like aluminum salts, and iron
salts, to remove phosphorus, these metal salts react upon dissolved phos-
phorus, but not upon insoluble phosphorus.
ii) When the mole ratio, Al/, Fe/P, or (Al + Fe)/P, calculated based on dis-
solved phosphorus concentration in influent is set constant, there is a
rectilinear relationship between the dissolved phosphorus concentration in
influent and that in the effluent.
iii) The concentration of dissolved phosphorus in influent to which the co-
efficient shown in Table 4.1 prepared for determing the concentration of dis-
solved phosphorus in effluent and mole ratio based on the concentration of
dissolved phosphorus in influent can be applied should preferably be in the
range of 1.5 to 10 mg.P/lit. for influent to the primary settler and 0.5 to 3
mg.P/lit. for secondary effluent.
iv) Even if the mole ratio is set constant, the removal of dissolved phosphorus
increases with increase in the concentration of dissolved phosphorus in
influent.
v) The difference of the concentration of dissolved phosphorus after treatment
due to difference in the concentration of dissolved phosphorus in influent
decreases with increase in mole ratio, is reduced to zero at a certain mole
ratio, and then turns up from there on.
vi) So far as the removability of phosphorus is concerned, alum and MICS lie
almost on the same level, while ferric chloride is poorer than them. In the
experiment using these three metal salts, pH control was not carried out.
vii) Removal of dissolved phosphorus is a little better in secondary effluent than
in raw sewage, though the difference is not so large.
viii) The results obtained in the experiment concerning the relationship betweeen
target removal of dissolved phosphorus and coagulant dosage are shown in
Tables 4.2 and 4.3.
160
-------
4.2 COMPARISON OF COAGULANT CONSTANT FEED AND MOLE RATIO
CONTROL
It is clarified under item 4.1 that in the phosphorus removal by metal salts
precipitation, the dissolved phosphorus concentration in effluent is dependent on
the mole ratio of dosed metal salts to dissolved phosphorus in influent as well as
on the concentration of dissolved phosphorus in influent.
In sewage treatment plant, usually, the influent flow and the dissolved phos-
phorus concentration in influent are changeable.
In order to minimize the loading of dissolved phosphorus in effluent mole
ratio control method in which the metal salts dosage is controlled to make the
mole ratio constant and constant feed method in which metal salts are fed at a
constant rate were put to comparison study with reference to the same coagulant
and the same total dosage.
To this purpose, experiments were carried out in the following way.
"A" sewage treatment plant in the suburbs of Tokyo covering a population
of 11,300 with a separate sewer system and undertaking secondary treatment in
step aeration process with two hours of aeration time, was picked up.
An automatic sampler was used to take its secondary effluent every hour for
24 hours in order to obtain influent for the experiment, and 24 influents were
analyzed of dissolved phosphorus.
In the constant feed method, alum was dosed to make Al/P mole ratios of 1,
2 and 3 with respect to the mean value of the concentration of dissolved phos-
phorus in influents. In the mole ratio control method, alum was dosed so that
Al/P mole ratio could be 1, 2 and 3 with respect to dissolved phosphorus in each
influent. The samples added with alum (24 x 2 x3 = 144 test tubes) were put to
jar test, and total dissolved phosphorus (H2 SO4 digestion) was analyzed each.
4.2.1 WHERE INFLUENT FLOW IS SET CONSTANT
Fig. 4.7 shows time-dependnet changes of inlfuent flow rate and the con-
centration of dissolved phosphorus in both influent and effluent.
Fig. 4.8 refers to constant feed method and mole ratio control method, and
shows their relationships between the concentration of dissolved phsophorus in
influent and the removal of dissolved phosphorus. The concentration of dissolved
phosphorus in influent recorded a maximum value of 6.73 mg.P/lit. at noon,
a minimum 1.73 mg.P/lit. at 7 a.m. and 3.36 mg.P/lit. on the average. The ratio
of the maximum to the minimum was 3.9. In the constant feed method, the
maximum to minimum ratio of dissolved phosphorus in effluent was 7.5, 14.9
and 17.5 for the mole ratios of 1, 2, and 3, respectively, while in the mole ratio
control method, the corresponding maximum to minimum ratio was 3.1, 2.8 and
4.4. At any mole ratio, the mole ratio control method could make smaller the
change in the concentration of dissolved phosphorus in effluent than the constant
feed method.
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From Fig. 4.8, it is found that in the constant feed method, the removal of
dissolved phosphorus decreased with increase in the concentration of dissolved
phosphorus in influent.
This is because as alum dosage was constant, the mole ratio (Al/P) decreased
with increse in the dissolved phosphorus concentration in influent. For this
reason, the lower the dissolved phosphorus concentration in influent, the smaller
the residual total phosphorus concentration, sending up the maximum to mini-
mum ratio of dissolved phosphorus in effluent. On the other hand, the mole ratio
control method increased the removal of dissolved phosphorus with increase in
the concentration of total dissolved phosphorus in influent just as the tendency
discussed under item 4.1; namely, the maximum to minimum ratio of dissolved
phosphorus in effluent did not become so large.
Assuming that the influent flows were equal to the average flow rate of "A"
sewage plant at that sampling day (87 m3 /hr), the dissolved phosphorus loadings
of influent and effluent, average removal and concentration are as shown in Table
4.4.
According to Table 4.4, the mole ratio control can reduce dissolved phos-
phorus in the effluent irrespective of mole ratios as compared with the constant
feed method. At mole ratios of 1, 2, and 3, the dissolved phosphorus loading in
the effluent in the mole ratio control method was 91%, 86% and 81% of the
corresponding values achievable by the constant feed method.
Fig. 4.9 shows the relationship between the dissolved phosphorus concentra-
tion in influent and the difference in dissolved phosphorus concentration after
treatment between in the constant feed method and in the mole ratio control
method. According to Fig. 4.9, it is found that a turn of tendency is seen at an
average dissolved phosphorus concentration of 3.36 mg.P/lit.
Assuming that these two demarcated ranges can each be replaced with a
straight line, respective regression straight lines can be determined as shown in
Table 4.5.
It is found from Table 4.5 that irrespective of whether the mole ratio is 1, 2
or 3, the slope (a) is larger in the case where the average dissolved phosphorus
concentration in influent is larger than 3.36 mg.P/lit. as compared with the case
where the average concentration is lower.
This difference in slopes means that the constant feed control increases the
solved phosphorus in the constant feed method decreases with increase in the con-
centration of dissolved phosphorus in influent whereas the mole ratio control
increases it to the contrary.
This difference is slope means that the constant feed control increases the
dissolved phosphorus loading in the effluent than the mole ratio control method.
4.2.2 WHERE INFLUENT FLOW IS CHANGEABLE
The constant feed in the case of influent flow change assumed a method of
keeping the coagulant dose per unit volume of influent at a constant value.
In the mole ratio control method, dosage was so made as to be proportional
to the influent flow rate and the concentration of dissolved phosphorus in the
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influent in an attempt to keep the mole ratio (Al/P) always constant.
Fig. 4.10 shows time-dependent changes of dissolved phosphorus loading in
the influent and effluent which are determined by multiplying the influent flow
rate shown in Fig. 4.7 by the concentrations in fluent and effluent of dissolved
phosphorus.
In connection with this, daily total laoding, removal, average concentration
(quotient obtained by dividing daily dissolved phosphorus loading in the effluent by
daily influent flow), and Al consumption are shown in Table 4.6.
According to Table 4.6, it is found that dissolved phosphorus loading is
lower in the mole ratio control method than in constant feed method.
However, the mole ratio control method consumes 6.7% more Al than the
constant feed method. This is because the influent flow was comparatively large
when the concentration of dissolved phosphorus in influent was higher than the
average.
In order to make comparison on a same Al consumption basis, the mole
ratios for the mole ratio control were taken as 1/1.067 = 0.94 and in the same
way, 1.87 and 2.81, and the corresponding loadings of dissolved phosphorus in
the effluent were determined from Fig. 4.11 and compared with the values listed
in Table 4.3 for the constant feed method.
In this case, at mole ratios of 1, 2 and 3 in the constant feed method, the
mole ratio control method reduced daily total loading of dissolved phosphorus in
effluent to 93%, 91% and 88%, respectively.
Qualitatively speaking, there may be the following effects of the way of
correspondence between the time change of influent flow and the time change of
dissolved phosphorus in influent on the daily total loading of dissolved phosphorus
in the effluent.
i) Where the influent flow and the dissolved phosphorus concentration in
influent are proportional to each other:
When the constant feed method and mole ratio control method are practised
on the same mole ratio, the mole ratio control method even more reduces
the dissolved phosphorus loading in the effluent, because when the con-
centration of dissolved phosphorus in influent is larger than the average in
which the mole ratio control method better removes dissolved phosphorus
than the constant feed method, the flow rate is larger than the average.
Al dosage, however, becomes larger in the mole ratio control method owing
to the reason explained above.
Accordingly, if the mole ratio control is carried out on the same Al con-
sumption with the constant feed method, the mole ratio of the mole ratio
control becomes smaller than referred to in the constant feed mehod.
The mole ratio control method is agreeable in that the dissolved phsophorus
loading of influent at a point where the dissolved phosphorus removal be-
comes larger than in the constant feed method, is larger, but is disagreed in
that the mole ratio becomes smaller.
ii) Where the influent, flow and the dissolved phosphorus concentration in
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influent are in inverse proportion to each other:
This is quite contrary to the tendency examined under item i) above. Name-
ly, the mole ratio control is disagreed in that the dissolved phosphorus load-
ing in the influent at a point where the removal becomes larger than the
constant feed mehtod becomes smaller, but is agreeable in that the mole
ratio becomes larger.
To follow Case (a), 9:00 flow which was maximum and 13:00 dissolved
phosphorus concentration which was also maximum were adjusted to have con-
curred, and calculations were made.
To follow Case (b), 2:00 flow which was minimum and 13:00 concentration
which was maximum were adjusted to have concurred, and calculations were
made. Fig. 4.12 shows the relationship between the flow and concentration of
dissolved phosphorus for respective cases.
The computation results appear in Table 4.7. Table 4.7 also shows a case of
constant flow and another in which flow and phosphorus concentration concurred
really.
From Table 4.7, the comparison between the constant feed and the mole
ratio control in which the coagulant dosages are the same in Al reveals that which
method is more advantageous than the other is dependent on (1) mole ratio and
(2) way of correspondence between time changes of influent flow and the dis-
solved phosphorus concentration in influent.
In case where the mole ratio is 1 as referred to in the constant feed, the way
of correspondence between flow and concentration makes little difference, and
dissolved phosphorus loading after treatment in mole ratio control is 91 to 94%
of that after constant feed treatment. Similarly, the mole ratio of 2 develops a
loading range of 86 to 91%.
At the mole ratios of 3 in the constant feed, the loading changes depending
on the mode of correspondence between the flow and concentration; when the
flow tends to become in reciprocal proportion to phosphorus concentration, the
mole ratio control method becomes more advantageous.
4.2.3 CONSIDERATIONS
It is found that the mole ratio control method can reduce dissolved phos-
phorus loading in the effluent more than the constant feed method even when
compared on the same basis of alum consumption. (See Table 4.7)
It should be noted however that this take "A" sewage treatment plant as a
model and that the method presupposes that the measurment of flow and dis-
solved phosphorus concentration in influent is made continuously without time
delay.
"A" sewage treatment plant is a separate sewer type sewage treatment plant
located in a Danchi (housing complex) and is considered to have very changeable
concentration of dissolved phosphorus in the raw sewage, and secondary effluent.
For example, the Toba Sewage Treatment Plant in Kyoto (influent flow: approx.
4.20 million m3/d.) was found on a survey to have the phosphorus concentration
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in the secondary effluent changed in 24 hrs from a maximum of 2.12 mg.P/lit. to
a minimum of 1.76 mg.P/lit., with the maximum to minimum ratio at 1.20. If the
metal salts precipitation is applied to this less changeable sewage for removal of
phosphorus, the mole ratio control will not be able to exhibit the effects shown
in this experiment.
The measurement of influent flow will be accomplished easily in real time if
a suitable instrument is applied.
Even with the colorimetric analysis method which is the most promising at
present, the measurement of the concentration of dissolved phosphorus in the
influent will unavoidably take a time lag of 20 to 60 min.
The applicability of the mole ratio control method should therefore be
judged after due consideration of not only the results of jar test, but also con-
siderations time-dependent pattern of influent dissolved phosphorus concentration
and influent flow, as well as response characteristics of phosphorus analyzer avail-
able.
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4.3 RESULTS OF PILOT PLANT EXPERIMENTS
The Yokosuka Advanced Wastewater Treatment Pilot Plant has two systems of
precipitation; one using lime and the other using metal salts. Dealt with here are the
results of experiments on the precipitation using alum as coagulant in the metal salts
system and on the filtration. The operating conditions of alum precipitation and
filtration are shown in Table 4.8. Both flow rate of the influent, which is secondary
effluent, and alum dosage were kept constant throughout the experiments.
4.3.1 RESULTS OF WASTEWATER TREATMENT
Table 4.9 shows the average results of wastewater treatment.
a. Removal of suspended solids
Turbidity and suspended solids were removed about 30% by precipitation and
about 90% after filtration. With a view to improving the removal of suspended solids
in the sedimentation tank, the effects of dosage of ferric chloride and anionic poly-
mer as flocculation aids and of returning sludge were examined.
The mean values of the results are shown in Table 4.10, According to Table
4.10, the concentration of suspended solids in the effluent of the sedimentation
tank is found unaffected by a dose of 0 to 5.0 mg.Fe/1 of ferric chloride, a sludge
return ratio to influent of 0 to 30% and a dose of 0 to 0.5 mg/1 of polymer.
The concentration of suspended solids was relatively constant within the range
of 10 to 15 mg/1, independent on these test conditions. This will be clarified by
further investigations scheduled, including a test in which the overflow rate is to be
changed in the range of 10 to 100 m3 /m2 d and a test of a shallow settling device.
The Yokosuka pilot Plant is equipped with two filters, different in constitution
of media. (See Table 4.11). The media of the No.2 filter is coarser than that of No. 1
filter.
The quality of the filter effluent shown in Table 4.9 was obtained by analysis
of a composite sample consisted of effuents from No. 1 and No. 2 filters.
The filtration run length at a total head loss of 2 m was 15.0 hrs and 18.5 hrs
on the average for No. 1 filter and No.2 filter, respectively. Namely, the filtration
run length of No.2 filter was 1.32 times as long as that of No. 1 filter. On the other
hand, the average concentration of suspended solids in filter effluent was 1.0 mg/1
and 1.6 mg/1 for No. 1 filter and No. 2 filter, respectively, demonstrating that No. 1
filter, which used fine media, excelled No.2 filter.
b. Removal of phosphorus
Phosphorus and orthophosphate were removed respectively 90.3% and 91.7%
after filtration. Their average concentrations in the filter effluent were 0.173 mg.p/1
and 0.109 mg.P/1, respectively as shown in Table 4.9. The dissolved phosphorus in
effluent treated by metal salts can be estimated by the method discribed in Section
4.1 if the mole ratio of the dosed metal salts to phosphorus based on the dissolved
phosphorus concentration in influent and the dissolved phosphorus in influent are
known.
In the period when the data shown in Table 4.9 were collected, the dissolved
phosphorus was not analyzed. Therefore, the comparison of estimated and measured
concentrations in the effluent from sedimentation fank will be made using data
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shown in Table 4.10 and the values of coefficients listed in Table 4.1.
The average concentration of the dissolved
phosphorus in influent 1.411 mg.P/1
Mole ratio (Al/P) 3.19
Coeffecient a at mole ratio 3.19 0
Coeffecient b at mole ratio 3.19 0.25
Concentration of dissolved phosphorus in effluent (mg.P/1) = a-(concentration
of dissolved phosphorus in influent) + b = 0 x 3.19 + 0.25 = 0.25 (mg.P/1)
One the other hand, the average concentration of dissolved phosphorus in
effluent shown in Table 4.10 is 0.130 or roughly 50% of 0.25 mg.P/1 of estimated
value. The results of experiments by the Joint Working Group on Advanced
Wastewater Treatmnet discussed under Section 4.1 include data obtained from the
Shitamachi Sewage Treatment Plant, Yokosuka, where the pilot plant under
discussion is installed. Here, a similar result was obtained. Namely, when secondary
effluent is treated by alum precipitation at mole ratio of 3, dissolved phosphorus in
the effluent is estimated to be 0.279 mg.P/1, while the actual concentration was
about half the estimate or 0.142 mg.P/1 (concentration of dissolved phosphorus in
influent: 0.686 mg.P/1). Thus it is inferred that the dissolved phosphorus in the
secondary effluent of the Shitamachi Sewage Treatment Plant is easy to remove by
alum addition compared with effluents of other sewage treatment plants, and the
causes are to be studied.
In the experimental period during which the data listed in Table 4.9 were
collected, the average concentration of dissolved phosphorus in the in fluent of the
filter was 0.124 mg.P/1. On the other hand, phosphorus concentration in effluents
from No.l filter and No.2 filter were 0.075 mg.P/1 and 0.091 mg.P/1, respectively.
Hence in No.l filter, at least 0.049 mg.P/1 or 40% of dissolved phosphorus was
removed, while in No.2 filter 0.033 mg.P/1 or 27% was removed.
c. Removal of organic matter and bacteria
As to removal of organic motter by alum precipitation and filtration, removal
of BOD was the highest among BOD, COD by potassium permanganate, and COD by
potassium dichromate. Removals of COD by potassium dichromate and COD by
potassium permanganate were almost on the same level. The value of COD by
potassium permanganate was about one third that of COD by potassium dichromate.
The common bacteria were removed only 38.7% before filtration, but coli-form
bacteria were removed as much as 90.6%, showing that coli-form bacteria are easier
to remove than common bacteria.
4.3.2 RESULTS OF SLUDGE DEWATERING
Alum sludge from an alum sedimentation tank was thickened and dewatered by
means of a centrifuge. The centrifuge used for the test was the smallest one available
on market for use in sewage sludge dewatering, having a standard sludge feed rate of
1 m3 /hr., and was modified for the test purposes.
The characteristics of feed sludge, test conditions and dewatering results are
shown in Table 4.12. According to Table 4.12, it is found that alum sludge is hard to
dewater with a centrifuge without chemical dosage.
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Even with the result of test No. 4 which was the best among the results, the
rate of total solids captured in dewatered sludge was 48.4%, and water content of
dewatered sludge was 88.2%. At that time, the suspended solids in the centrate was
7,000 mg/1.
Then, alternative dewatering methods are called for, which may include: (1)
centrifugal dewatering with desage of polymer, (2) dewatering after being mixed
with organic sludge, (3) dewatering after freeze conditioning, and (4) use of filter
press or vacuum fieter.
Preliminary study of freeze conditioning was carried out using a home freezer
to freeze the alum sludge. The settling test for the alum sluage showed that the ratio
of the sludge volume after 30 min. settling to the intial volume was 27% for the
freeze conditioned sludge as against 95% for the non-treated, evincing that the
thickening rate can be improved sharply by the freezing and melting process. This
held also true with the lime sludge.
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4.4 DEVELOPMENT OF HIGH-RATE FLOCCULATION-SEDIMENTATION
SYSTEM - AN EXAMPLE OF ADVANCED WASTE TREATMENT TECH-
NICAL DEVELOPMENT AT A PRIVATE COMPANY -
In Japan, several types of chemical flocculation-sedimentation installation have
been introduced at water purification plants, etc. The chemical flocculation-sedi-
mentation system described here has been developed by a private company based on
a new concept. This system has some advantages compared with conventional ones:
for example, it can provide larger overflow rate, and floe becomes in a pellet state in
the sedimentation installation thereby, facilitating its treatment.
Because this new installation can remove the residual organic substances and
ortho-Phosphate in the secondary effluent with a high efficiency within a very
small site, many sewage works engineers in several cities have paid attention to it
with interest.
This is a report on pilot plant studies in Hiroshima and Fukuyama Cities.
This system will be assessed as an actual facility by the Japan Sewage Works
Agency's Committee of Technology Evaluations in 1976.
4.4.1 PRINCIPLES AND FEATURES OF THE INSTALLATION
This system is a flocculation-sedimentation installation of the sludge blanket
type in which both polymers and metal salts coagulants such as aluminum sulphate
and ferric chloride, are used. Since floes forming the sludge blanket are huge pellets,
as big as 5 to 10 mm, the installation has a good characteristic in terms of settling,
has fewer carry-overs of floes and can be designed to allow overflow rate of 300 m/d
or more.
The mechanism of formation of such huge pellets has not been fully under-
stood. But several experiments have proved that this installation is very effective to
remove colloidal organic matter and phosphate.
The pilot scale experimental facility used for the study is shown in Fig. 4.13.
Its major portion is composed of a 1.8m x 1.8m square flocculation-sedimentation
tank, a mixing tank which mix water and coagulants and tanks to dissolve coagulants.
An electromagnetic flow meter and an inflow control valve are provided.
A predetermined quantity of inflowing water is fed to the mixing tank and mixed
with inorganic coagulant (aluminum sulphate). Polymer is fed with pressure to the
piping between the mixing tank and the installation (flocculation-sedimentation
tank). The influent is sent to the installation from its bottom. Water and floes are
separated when they passethrough the sludge blanket zone consisting of granular
floes. Then water is discharged from the overflow weir. The separated floes gradually
grow by the coagulation action given by the inside impeller anto granular floes which
consists of the sludge blanket. The level of the sludge blanket which goes up gradual-
ly is detected by the ultrasonic sludge level sensor mounted a predetermined hight.
And by the operation of the sludge drawing valve which is connected electrically
with the sludge level sensor, the sludge blanket zone is maintained at a fixed level.
Originally, the installation was designed to use a square tank. But later it was
found that a square tank difficulties in maintaining the sludge blanket zone at a
fixed state at corners. Therefore, the installation was remodeled to use a octagonal
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tank, in which the sludge blanket zone could be kept at a fixed state. In an actual
facility, it is considered that circular type would be the best. In that case, the
maximum diameter will be 5.5 m considering the limit for the peripheral velocity of
impeller not to destroy the floe.
4.4.2 PILOT PLANT EXPERIMENT AT THE SENDA SEWAGE TREATMENT
PLANT, HIROSHIMA CITY
Experiments as to use of this high-rate flocculation-sedimentation system as
a tertiary treatment facility of waste water was conducted from Feburary to April,
1970, using the secondary effluent from the Senda Sewage Treatment Plant,
Hiroshima City, The Plant is a medium-sized treatment plant having a planned
serving population of 100,000 and adopting conventional activated sludge system.
i) Water quality of influent
Water quality of the secondary effluent (that is, influent to the high-rate floc-
culation-sedimentation system) during the period of experiments was as shown
in Table 4.13. Fig. 4.14 shows protted relations between suspended solids and
total CODMn m secondary effluent. From this figure, one can find it is known
that even though suspended solids are completely removed, about 4 to 5 mg/1
of soluble CODMn still remains.
ii) Time needed for accumulation of pellet-state sludge in the starting of operation
Operation was started under the following conditions:
Quantity of flow, 50m3 /hr; overflow rate, 250mm/min; dosing rate of alum,
50mg/l and dosing rate of polymer, l.Omg/1. Under these conditions, the
time needed for the blanket level to reach the predetermined height (i.e., 1.5m
above the inflow port) was about 10 hours when treating low SS secondary
effluent like one shown in Table 4.13.
iii) Effects of the dosing rate of alum on flocculation
Jar tests: Laboratory tests have been conducted with the secondary effluent
containing 15mg/l of suspended solids and 13.2mg/l of CODMn to which a
various quantity of alum was added. A good flocculation was observed when
alum dosage was 40mg/l as A12 (SO4)318H2O and flocculation was excellent
when dosage was 50mg/l.
Continuous tests: Effects of alum dosing rate on the quality of effluent were
examined under thi conditions as follows: overflow rate, 250mm/min;
retention time in buffled flocculator, 80 sec.; polymer dosing rate, lmg/1;
and dosing rate of alum, 50 to 60mg/l. Within the range of alum dosing rate
examined, differences in performance were not so significant. But in order to
form core floes in the sludge blanket, the alum dosing rate must be 40 to
50mg/l. If the rate is 30mg/l, the size of core floes is too small and the quality
of effluent tends to be slightly worse.
iv) Optimum period between dosing of alum and dosing of polymer
In this experiment, overflow rate was set at 250mm/min, dosing rate of alum,
at 50mg/l, that of polymer, at lmg/1, and mixing intensity in the flocculation
tank at 0.62 (kg.f-m/nr' sec). Under these conditions, the optimum period
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between dosing of alum and that of polymer was found to be 80 seconds or so.
v) Maximum overflow rate for stable operation
The effect of overflow rate on the stability of the sludge blanket was studied
under the condition of 50mg/l of alum dosing rate and lmg/1 of that of
polymer As a result, it was found that the critical up flow velocity is in the
vicinity of 300mm/min If the installation is designed to obtain more uniform
distribution of velocity throughout the sludge blanket, overflow rate may be
increased up to about 350mm/min.
vi) Thickening characteristic of excess flocculated-sedimented sludge
Thickening tests were carried out using samples taken from blanket slurry
which was formed under the conditions of 250mm/min of overflow rate, 40
to 50mg/l of alum dosing rate and l.Omg/1 of polymer dosing rate. A column
of the diameter of 70mm and the height of 120mm was used for the tests.
An example of the results is shown in Fig. 4.15 Sludge concentration reached
28 to 35g/l after 24 hours. From this result, it may be said that thickening-
characteristic is comparatively good.
vii) Quality of effluent
Table 4.13 shows quality of effluent which was obtained at the optimum
dosing rates of coagulants, and at overflow rates less than 280mm/min. It is
considered that effluent quality has no relation directly with changes in the
quality of influent. Insoluble CODMn, and insoluble BOD were removed very
effectively. Concentration of CODMn remaining in effluent is about 10% lower
than that of soluble CODMn in influent. From this, it can be considered that
part of soluble CODMn in influent was also removed. Orthophosphate was
removed very effectively although the orthophosphate concentration was rela-
tively low, 0.8~1.4mg/l.
4.4.3 PILOT PLANT EXPERIMENT AT THE SHINHAMA SEWAGE TREAT-
MENT PLANT, FUKUYAMA CITY
Experiments at the Shinhama Sewage Treatment Plant have been carried out
with effluent from the plant. Worse in quality than that of the Senda Sewage Treat-
ment Plant. They have been conducted with the following three types of effluents:
Type A: Effluent from modified activated sludge treatment process which
is overloaded.
Type B: Mixed effluent of three types of effluents, i.e., that from the
conventional activated sludge treatment facility, that from the
overloaded modified activated sludge treatment facility, and that
from the primary setting tank.
Type C: Mixed effluent of two types of effluents, i.e., that from the over-
loaded modified activated sludge treatment facility, and that from
the primary settling tank.
Qualities of these types of influents during each test period are shown in Table
4.14. Relations between CODMn and CODcr of Type A and Type B are shown in
Fig. 4.16. In the Figure both total COD and soluble COD are plotted and a high
correlation is found in both cases.
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As with experiments in Hiroshima, coagulants used in this pilot plant tests were
alum and polymer. The dosing rates of them are shown in Table 4.14. The overflow
rate was in the range of 330 to 350mm/min.
Quality of effluent obtained in this experiment is shown in Table 4.14. Also,
Fig. 4.17 shows removal characteristics of CODMn in the experiment. Summary of
the results are as follows:
a. Total CODMn of effluent depends on the concentration of soluble CODMn in
influent.
b. Total CODMn in effluent is always lower than soluble CODMn in influent.
From this, it is concluded that insoluble CODMn in influent is removed almost
completely and a part of soluble CODMn in influent (15~20%) is also removed.
c. Relations between soluble CODMn in influent and that in effluent are shown in
solid line in Fig. 4.18. Relations between soluble CODMn in influent and total
CODMn in effluent are shown in a broken line in the same figure. From Fig. 4.
18, it can be considered that 35% of soluble CODMn in influent was transferred
into insoluble CODMn by the flocculation-sedimendation process, 30 to 35%
of which was removed in the sludge blanket.
d. Fig. 4.19 shows the relation between total CODMn and soluble CODMn in
effluent. From this Figure, it can be said that 80% of total CODMn in effluent
is soluble.
Insoluble CODMn carried over from the overflow weir of this installation is
floe with comparatively low specific gravity which is formed by conversion of
soluble CODMn in influent into insoluble one through the flocculation-sedi-
mentation process.
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Table 4.1 Coefficients a and b, and Standard Deviation of Regression Line
Coagulant
A12(S04)3
FeCl3
MICS
Mole
ratio
0.5
1
1.5
2
2.5
3
3.5
4
0.5
1
1.5
2
2.5
3
3.5
4
0.5
1
1.5
2
2.5
3
3.5
4
Influent to the primary settler
a
0.743
0.472
0.223
0.074
0.000
-0.029
-0.028
-0.039
0.671
0.448
0.248
0.088
0.014
0.006
0.001
-0.010
0.703
0.457
0.239
0.115
0.027
-0.002
-0.007
-0.008
b
0.149
0.390
0.632
0.693
0.610
0.497
0.368
0.343
0.381
0.486
0.703
0.877
0.782
0.539
0.381
0.332
0.214
0.368
0.517
0.490
0.469
0.363
0.230
0.167
a
0.218
0.266
0.255
0.169
0.158
0.144
0.121
0.091
0.194
0.315
0.363
0.402
0.388
0.278
0.238
0.042
0.128
0.240
0.276
0.229
0.201
0.181
0.103
0.067
Secondary effluent
a
0.692
0.465
0.266
0.119
0.057
0.011
0.807
0.545
0.360
0.234
0.146
0.094
0.810
0.561
0.331
0.148
0.029
-0.002
b
0.156
0.272
0.316
0.357
0.318
0.271
0.030
0.207
0.306
0.282
0.270
0.240
0.024
0.163
0.279
0.358
0.373
0.328
a
0.122
0.170
0.211
0.209
0.188
0.133
0.147
0.153
0.156
0.104
0.098
0.071
0.103
0.099
0.138
0.131
0.113
0.087
The number of data is 14 or 15.
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Table 4.2 Objective of Dissolved Phosphorus Removal vs. Coagulant Dosage and Mole Ratio
Influent to the primary settler
P-D in
influent
(mg/B)
2
4
6
8
10
2
4
6
8
10
2
4
6
8
10
2
4
6
8
10
2
4
6
8
10
Objective
P-D in
effluent
(mg/E)
0.1
0.2
0.3
0.5
1.0
A12 (S04)3
Mole
ratio
_
—
4.1
3.7
3.5
—
3.8
3.5
3.2
3.0
3.6
3.3
3.0
2.9
2.8
2.8
2.7
2.7
2.6
2.6
1.6
2.0
2.1
2.2
2.2
Al(mg/£)
21.4
25.8
30.5
13.2
18.3
22.3
26.1
6.3
11.5
15.7
20.2
24.4
4.9
9.4
14.1
18.1
22.6
2.9
7.0
11.0
15.3
19.2
FeCl3
Mole
ratio
_
—
—
-
_
—
—
—
-
(4.2)
3.9
3.9
3.8
3.7
3.1
3.2
3.2
3.3
3.3
2.3
2.4
2.4
2.5
2.5
Fe(mg/e)
(15.1)
28.1
42.1
54.7
66.6
11.1
23.0
34.6
47.5
59.4
8.3
17.3
25.9
36.0
45.0
MICS
Mole
ratio
—
—
(4.1)
3.7
3.6
3.5
3.5
3.4
3.3
3.3
3.2
3.2
3.2
3.1
2.5
2.6
2.7
2.7
2.8
1.5
1.9
2.1
2.3
2.3
Al + Fe
(mg/fi)
(31.8)
35.9
7.0
13.6
20.4
26.4
32.0
6.4
12.4
18.6
24.9
30.1
4.9
10.1
15.7
21.0
27.2
2.9
7.4
12.2
17.9
22.3
Objective
P-D
removal
(%)
98
95
90
85
80
A12 (S04)3
Mole
ratio
_
4.0
3.4
3.0
—
3.8
3.0
2.8
2.6
—
3.0
2.5
2.3
2.2
3.6
2.5
2.2
2.1
2.0
3.1
2.2
1.9
1.8
1.8
Al(mg/£)
20.9
23.6
26.1
13.2
15.7
19.5
22.6
10.4
13.1
16.0
19.2
6.3
8.7
11.5
14.6
17.4
5.4
7.7
9.9
12.5
15.7
FeCl3
Mole
ratio
_
—
—
-
—
—
3.8
3.5
3.3
—
3.5
2.9
2.6
2.5
(4.2)
2.9
2.5
2.2
2.1
3.5
2.6
2.2
2.0
1.9
Fe(mg/£)
41.0
50.4
59.4
25.2
31.3
37.4
45.0
(15.1)
20.9
27.0
31.7
37.8
12.6
18.7
23.8
28.8
34.2
MICS
Mole
ratio
_
4.0
3.5
3.3
_
3.6
3.2
2.9
2.8
3.6
2.9
2.6
2.4
2.3
3.3
2.5
2.2
2.1
2.0
2.8
2.2
2.0
1.9
1.8
Al + Fe
(mg/B)
23.3
27.2
32.0
14.0
18.6
22.5
27.2
7.0
11.3
15.1
18.6
22.3
6.4
9.7
12.8
16.3
19.4
5.4
8.5
11.7
14.8
17.5
Al/p = 27/31 =0.871 Fe/p = 55.8/31 = 1.8
-------
Table 4.3 Objective of Dissolved Phosphorus Removal vs. Coagulant Dosage and Mole Ratio
Secondary effluent
P-D in
influent
(mg/fi)
1
2
3
1
2
3
1
2
3
Objective
P-D in
effluent
(mg/£)
0.3
0.5
1.0
A12 (S04)3
Mole
ratio
2.9
3.0
3.0
1.9
2.2
2.4
0
1.3
1.6
Al(mg/£)
2.5
5.2
7.8
1.7
3.8
6.3
0
2.3
0.2
FeCl3
Mole
ratio
(33)
-
-
2.1
2.7
3.1
0
1.5
2.0
Fe(mg/£)
5.9
-
-
3.8
9.7
16.7
0
5.4
10.8
MICS
Mole
ratio
(3.3)
(3.2)
(3.1)
2.0
2.3
2.4
0
1.4
1.8
Al + Fe
(mg/fi)
(3.2)
(6.2)
(9.0)
1.9
4.5
7.0
0
2.7
5.2
Objective
P-D
removal
(%)
90
85
80
A12 (S04)3
Mole
ratio
—
(3.5)
3.0
—
3.0
2.6
(3.5)
2.6
2.3
Al(mg/£)
6.1
7.8
5.2
6.8
3.0
4.5
6.0
FeCl3
Mole
ratio
—
-
-
—
-
(3.3)
—
(3.2)
2.8
Fe(mg/£)
—
-
-
_
-
17.8
—
11.5
15.1
MICS
Mole
ratio
—
-
(3.1)
—
(3.2)
2.5
—
2.7
2.2
Al + Fe
(mg/C)
(9.0)
(6.2)
7.3
5.2
6.4
tn
-------
Table 4.4 Comparison between Constant Feed and Mole Ratio Control (Influent flow is constant.)
Mole ratio
(Al/p)
1
2
3
Dissolved phosphorus
Items
Lo*
Co**
Re***
Lo
Co
Re
Lo
Co
Re
Influent
7.01
3.36
—
7.01
3.36
—
7.01
3.36
-
Constant
feed®
4.46
2.14
36
2.38
1.14
66
0.89
0.43
87
Mole ratio
control (b)
4.07
1.95
42
2.06
0.99
71
0.73
0.35
90
©/®
0.91
-
0.86
-
0.81
-
®
-------
Table 4.5 Coefficients of Regression Lines of Fig. 4.9
Dissolved phosphorus
in influent
3.36mg-P/8 max.
3.36mg-P/2 min.
Coefficient
a*
b*
r**
a
b
r
Mole ratio (Al/p)
1
0.574
-1.984
0.884
0.110
-0.504
0.311
2
0.606
-2.200
0.873
0.189
-0.738
0.754
3
0.452
-1.640
0.977
0.091
-0.430
0.553
* [(P-D in effluent treated by constant feed) - (P-D in effluent treated by mole ratio controle)]
= a • [P-D in influent] + b
** correlation coefficient
- 177
-------
Table 4.6 Comparison between Constant Feed and Mole Ratio Control (Influent flow changes.)
Mole ratio
(Al/p)
1
2
3
Dissolved phosphorus
Items
Lo*
Co**
Re***
Lo
Co
Re
Lo
Co
Re
Influent
7.48
3.59
-
7.48
3.59
-
7.48
3.59
-
Constant
feed @
4.84
2.32
35
2.65
1.27
65
1.04
0.50
86
Mole
ratio
control
4.34
2.08
42
2.20
1.06
71
0.72
0.35
90
©1®
0.90
0.83
0.69
®-®
0.50
0.24
-7
0.45
0.21
-6
0.32
0.15
-4
Al dosage
Constant
feed ©
6.11
12.22
18.33
Mole
ratio
control
6.52
13.04
19.55
a/©
1.067
*Lo: load (kg-P/D)
**Co: average concentration (mg-P/C)
' Re: removal (%)
178
-------
Table 4.7 Comparison between Constant Feed and Mole Ratio Control
Mode
ratio
in
cons-
tant
feed
1
2
3
Correspondence of influent
flow and dissolved
phosphorus in influent
Direct proportion****
Actual correspondence****
Influent flow is constant
****
Inverse proportion
Direct proportion
Actual correspondence
Influent flow is constant
Inverse proportion
Direct proportion
Actual correspondence
Influent flow is constant
Inverse proportion
Mole ratio
in mole
ratio control
0.83
0.94
1.00
1.17
1.66
1.87
2.00
2.34
2.48
2.81
3.00
3.50
Dissolved phosphorus
Item
Lo*
Co**
Re***
Lo
Co
Re
Lo
Co
Re
Lo
Co
Re
Lo
Co
Re
Lo
Co
Re
Lo
Co
Re
Lo
Co
Re
Lo
Co
Re
Lo
Co
Re
Lo
Co
Re
Lo
Co
Re
Influent
8.46
4.06
_
7.48
3.59
—
7.01
3.36
—
6.00
2.88
—
8.46
4.06
—
7.48
3.59
—
7.01
3.36
—
6.00
2.88
—
8.46
4.06
—
7.48
3.59
-
7.01
3.36
—
6.00
2.88
-
Constant
feed @
5.86
2.81
31
4.85
2.32
35
4.46
2.14
36
3.54
1.70
41
3.26
1.56
62
2.65
1.27
65
2.38
1.14
66
1.75
0.84
71
1.34
0.64
84
1.04
0.50
86
0.89
0.43
87
0.58
0.28
90
Mole
ratio
control
®
5.30
2.54
37
4.50
2.16
40
4.07
1.95
42
3.34
1.60
44
2.97
1.42
65
2.40
1.15
68
2.06
0.99
71
1.52
0.73
75
1.38
0.66
84
0.92
0.44
88
0.73
0.35
90
0.37
0.18
94
® / ®
0.90
—
0.93
-
0.91
—
0.94
-
0.91
—
0.91
—
0.86
—
0.87
—
1.03
—
0.88
-
0.81
—
0.64
-
®-®
0.56
0.27
-6
0.35
0.16
-5
0.39
0.19
-6
0.20
0.10
-3
0.29
0.14
-3
0.25
0.12
-3
0.32
0.15
-5
0.23
0.11
-4
-0.04
-0.02
0
0.12
0.06
-2
0.16
0.08
-3
0.21
0.10
-4
*Lo: load (kg-P/C)
**Co: average concentration (mg-P/C)
***
#***
Re: removal (%)
refer to Fig. 6
- 179 -
-------
Table 4.8 Operation Condition of Alum Precipitation and Filtration
Process
Influent
Alum precipitation
Filtration
Condition
Secondary effluent
Coagulant A12(S04)3
Dosage 3.9 mg-Al/2
Influent flow 216m3/D
Overflow rate of alum sedimentation tank 50m3/m2-D
Gravity flow, constant head, dual media
Initial flow rate 218m/D
Total head loss at filtration end
180
-------
Table 4.9 Results of Alum Precipitation and Filtration at Yokosuka Pilot Plant
Temp. (°C)
pH
Turbidity
SS
P
P. ortho
CODcr.
CODMn.
BOD
ABS
Common bact.
Colo-form bact.
mg/C
%*
mg/C
%
mg-P/C
%
mg-P/e
%
mg/£
%
rng/2
%
mg/C
%
mg/e
%
N/mC
%
N/mC
%
Influent
(secondary effluent)
11.7
1.22
21.1
10.5
1.782
1.309
45.8
14.3
14.6
0.192
3 1 ,000
3,600
Effluent from alum
sedimentation tank
6.96
18.2
32.7
6.9
34.2
0.691
61.2
0.472
63.9
30.6
33.1
10.4
27.3
6.5
55.7
0.180
6.3
Effluent from
filter
7.12
2.3
91.4
1.3
87.7
0.173
90.3
0.109
91.7
23.8
48.1
7.1
50.6
4.5
69.0
0.127
33.9
19,000
38.7
340
90.6
* Removal to influent
- 181
-------
Table 4.10 Results of Alum Sedimentation Tank Operation
Alum Dosage: 3.9 mg. A2/2
Overflow Rate of Alum Sedimentation Tank: 50 m3/m2 -D
^"^\^^ Condition
Item ^~"^-^^^
Temp, of influent (°C)
PH
SS (mg/2)
P (mg/J2)
P-D (mg/B)
© *
(T> **
©
©
©
©
©
©
Fe+++ addition (mg/2)
0
18.7
7.20
6.92
22.8
13.0
1.487
0.348
0.836
0.061
0.5
19.5
7.34
6.98
24.0
14.5
1.906
0.461
1.331
0.105
2.0
20.5
7.24
6.93
31.0
15.4
3.320
0.663
2.265
0.142
5.0
19.9
7.28
6.89
27.0
13.8
2.054
0.689
1.666
0.100
P.eturn sludge (% to influent flow)
0
22.0
7.24
7.03
9.4
12.7
2.538
0.783
1.882
0.270
10
21.3
7.29
6.96
11.6
8.1
1.709
0.695
1.226
0.044
20
21.0
7.22
6.92
16.8
13.7
2.170
0.779
1.569
0.233
30
22.2
7.42
7.09
37.0
15.1
2.020
0.590
1.297
0.076
Polymer addition (mg/C)
0
24.5
7.46
7.11
4.3
5.7
1.895
0.118
1.155
0.127
0.1
24.6
7.26
7.12
11.7
12.6
1.864
0.194
1.647
0.212
0.5
24.8
7.36
7.08
25.0
14.4
1.156
0.347
0.649
0.065
* © Influent (secondary effluent) ** (2) Effluent from alum sedimentation tank
-------
Table 4.11 Constitution of Filtration Media
Anthercite coal
Silica sand
Depth (cm)
Effective size (mm)
Uniformity coefficient
Depth (cm)
Effective size (mm)
Uniformity coefficient
No. 1 filter
30
0.8
1.4
30
0.45
1.2
No. 2 filter
30
1.2
1.4
30
0.55
1.2
183
-------
Table 4.12 Results of Alum Sludge Dewatering by Centrifuge
Character of Feed Sludge (Thickend Sluge)
Water Content = 98.6%, A£ = 131 mg/g-dry sludge
P = 36.8 mg/g-dry sludge, VSS = 463 mg/g-dry sludge
ExpeA
No. \
1
2
3
4
5
6
Experiment condition*
Centirfugal
force (G)
1,000
2,000
3,000
2,000
2,000
2,000
Sludge feed
rate (m3/h)
1.26
1.38
1.40
0.46
0.81
1.79
Conveyer
revolution
(rpm)
6
6.5
8
6.5
6.5
6.5
Dewatered sludge
Rate of total
solid captured
(%)
28.7
26.2
33.8
48.4
35.1
22.5
Water content
(%)
86.9
86.7
86.0
88.2
86.6
85.4
Suspended
solids in
centrate (g/2)
10.5
9.7
9.0
7.0
8.7
10.3
'Pool depth is 1.5-2.4 mm.
184
-------
Table 4.13 Influent and Effluent Quality of the Highrate
Chemical Coagulation Clarification System
Item
Suspended solid (mg/C)
PH
M-Alkalinity (mg/£)
Total-CODMn (mg/K)
Soluble-CODMn (mg/E)
Suspended-CODMn (mg/C)
Total-BOD5 (mg/2)
Soluble-BOD; (mg/£)
P04- (mg/fi)
Influent
Range
12 ~ 32
6.95- 7.65
102 -140
7.4 ~ 11.0
5.8 - 8.1
1.3 ~ 7.0
7.6 ~ 14.0
2.8 ~ 3.3
0.8 ~ 1.4
Mean
18
7.2
-
9.0
6.5
2.2
11.2
3.0
0.9
Effluent
range
1~10 (2-3 almost)
-
-
4.8-7.7
4.3-6.8
-
trace —3.0
trace —1.0
trace
- 185
-------
Table 4.14 Water Quality of Influent and Effluent, and Chemical Dosing Rate
Items
Suspended solid
pH
M-Alkalinity
Total CODMn
Soluble CODMn
Total CODcr
P04
BODS
Alum dosing rate
Polymer dosing rate
Unit
mg/S
rng/C
mg/£
mg/e
mg/e
mg/£
mg/e
mg/£
mg/£
Type A
Influent'
18 ~ 47
7.15- 7.6
140 -270
20 ~ 40
10 ~ 27
80 -166
3.3 ~ 11
18 ~ 30
Effluent
2 -14
6.4- 6.8
-
9.5-22.5
7.6-18.4
67 -96
0.5- 1.6
3-6
60-80
1-1.2
Type B
Influent
13 -145
7.15- 7.58
117 -310
21 -106
15 ~ 40
144 -197
1.8 ~ 14
20 ~ 30
Effluent
4-25
6.3- 6.7
-
10 ~ 36
10 - 25
96 -108
0.9~ 1.4
4~22
90-130
1-1.2
Type C
Influent
19 -248
7.25- 7.5
143 -270
19 ~ 74
13 - 39
-
-
106
Effluent
-15
6.3- 6.8
-
8 -30
11.1-15.5
-
-
30.5
80-140
1-1.2
-------
7 -,
00
4 .
3 -
D D'
n
±
04A
• Influent to the Primary Settler, Mole Ratio 1
rj Secondary Effluent, Mole Ratio 1
A Influent to the Primary Settler, Mole Ratio 2
A Secondary Effluent, Mole Ratio 2
• Influent to the Primary Settler, Mole Ratio 3
O Secondary Effluent, Mole Ratio 3
Coagulant: M2 (S04)3
A A
A A
• * •
0 1
3 4 5 6 7 8 9 10 11 12 13 14 15
Phosphorus in Influent (mg-P/2)
Fig. 4.1 Phosphorus in Influent vs. Dissolved Phosphorus in Effluent (Mole ratios are based on
phosphorus in influent.)
-------
7 ,
OO
E
3
O
_C
OH
C/O
o
a.
•o
• Influent to the Primary Settler, Mole Ratio 1
D Secondary Effluent, Mole Ratio 1
A Influent to the Primary Settler, Mole Ratio 2
A Secondary Effluent, Mole Ratio 2
• Influent to the Primary Settler, Mole Ratio 3
O Secondary Effluent, Mole Ratio 3
Coagulant: A22 (S04)3
a D
*n • D
a aa
A A
o
o • o o
• •
1 2345678
Dissolved Phosphorus in Influent (mg-P/2)
Fig. 4.2 Dissolved Phosphorus in Influent vs. Dissolved
Phosphorus in Effluent (Mole ratios are based
on dissolved phosphorus in influent.)
- 188
-------
100-
90-
80-
' 70-
"I 60-
o
SO
-''-' ~
Q 40-
g 30-
I
20-
10-
0
Sample: Influent to the Primary Settler
Coagulant: AC2 (S04)3
0123 4567 89
Dissolved Phosphorus in Influent (mg-P/2)
Fig. 4.3 Dissolved Phosphorus in Influent vs. Removal
of Dissolved Phosphorus
10
189
-------
Sample: Influent to the
Primary Settler
Coagulant: A£2 (S04)3
1234
Mole Ratio
Fig. 4.4 Mole Ratio vs. Dissolved
Phosphorus in Effluent
190 -
-------
Sample: Influent to the Primary
Settler
Coagulant: A£2 (S04)3
Sample: Influent to the Primary
Settler
Coagulant: A£2 (S04)3
Mole Ratio
Fig. 4.5 Mole Ratio vs. a
Fig. 4.6 Mole Ratio vs. b
-------
200
oo
6 •
5 -
2 4
o
c.
2 3
•3 2
1 -
0 J
[Mole Ratio Control]
[Constant Feed]
Mole Ratio 1 Mole Ratio 3
10 12 14 16 18 20 22 24 246
10 12 14 16 18 20 22 24
Fig. 4.7 Relationship between Influent Flow, Dissolved Phosphorus Concentration, and Time
-------
O
.s
100,
90.
80-
70-
60-
50"
40.
30-
20-
10
0
[Constant Feed]
01 234567
Dissolved Phosphorus in Influent (mg-P/S)
100
90 •
80'
70 -
> 60
I
V
* 50
o
a- 40
30 -
Q 20 -
10 -
[Mole Ratio Controle]
O
Mole Ratio (AB/P)
O 3
A 2
D 1
1 234567
Dissolved Phosphorus in Influent (mg-P/£)
Fig. 4.8 Dissolved Phosphorus in Influent vs. Dissolved Phosphorus Removal
-------
oo
o
O
Pi
_«
o
§
(U
_c
Q
I
•a"
o
U
2.4 -
2.2 -
2.0
1.8 •
1.6
1.4 •
1.2
1.0 -
0.8 •
0.6
0.4
0.2
I
w _
Q
a.
0
0.2
0.4
0.6
a Mole Ratio 1
A Mole Ratio 2
• Mole Ratio 3
A
D
Mole Ratio 3
Fig. 4
01234567
Dissolved Phoshorus in Influent (mg-P/2)
9 Dissolved Phosphorus in Influent vs. Difference of
Dissolved Phosphorus in Effluent between two
Coagulant Feed Methods
- 194 -
-------
noo •
1000 -
900
800
ST
?" 700-
OO
o 600 -
o.
o
£ 500
300 -
c
T3
03
5 200-
100 -
(Constant Feed)
Influent
(Mole Ratio Control)
Influent
10 12 14 16 18 20 22 24
Fig. 4.10 Relationship between Loading of Dissolved Phosphorus and Time
-------
tq
G
o
a.
CO
o
J=l
0,
-a
tu
_>
"o
7 -
6 -
4 -
Constant Feed
Mole Ratio Control
0123
Mole Ratio (Al/P)
Fig. 4.11 Mole Ratio vs. Dissolved Phosphorus Load
in Effluent
196
-------
t Flow(m3/h)
Influeni
200 -,
180 -
160 -
140 -
120 •
100 -
80 -
60 -
40 -
20 -
n
0
o
o
0
UD
0
o
o
o
o
o o
0
o
0 0
0
&°0
200-
180-
160-
140-
•? 120-
| 100-
"c
OJ
,H 80 .
C
60
40 -
20 -
0
10
01 234567
Dissolved Phosphorus in Influent (mg.P/^)
(Influent Flow is in Direct Proportion to Phosphorus)
13
Hour is indicated by number.
p
0
u_
0)
i:
c:
200 '
180 -
160 -
140 '
120 -
100 -
80 -
60 -
40 -
20 -
0
0
0
o
o
o
o
o
o
0
0
°0
o
0 0
o
00° O
01 234567
Dissolved Phosphorus in Influent (mg-P/v.)
(Correspondence of Influent Flow and Phosphorus
is Actual)
01234567
Dissolved Phosphorus in Influent (mg-P/t)
(Influent Flow is in Inverse Proportion to
Phosphorus)
Fig. 4.12 Relationship between Dissolved Phosphorus and Influent Flow Used for Calculation
-------
OC
Alum Dosing Pump
Fresh Water
Electromagnetic Flow Meter
Signal from Sludge Lebel Sensor
Excess Sludge
Effluent
Influent
Fig. 4.13 Flow Diagram of High Rate Chemical Coagulation and Clarification
-------
30 —i
20 —
CX
vf
•g
1
I—I
<+-(
O
(/)
T3
"o
in
T3
I 10
o o
5 10 15
Total CODMn of Influent (mg/£)
Fig. 4.14 Corelation between Suspended Solids and Total CODMn
199
-------
o
o
-o
c
3
o
03
GO
c*-
O
BO
Over Flow Rate 250 mm/min
Alum Dosing Rate 50 mg/Q
Polymer Dosing Rate 1 mg/£
Initial Concentration of S.S. 3.3 g/8
Ultimate Concentration of S.S. 2.8 g/6
(after 24 hr)
40 -
20 -
120
Settling Time
Fig. 4.15 Settability of Excess Sludge
150
180 min
24 Hr
-------
250 -,
200 -
150 -
c*
~S2
u
Q
O
U
100 -
50 -
i
10
I
20
r
40
30
CODMn (mg/<9
Fig. 4.16 Corelation between CODMn and CODCr of Influent
I
50
201
-------
Blend A
Soluble CODMn of Influent (mg/C)
Fig. 4.17 Corelation of Inf. Solube CODMn and Eff. Total COD
-------
01
30-,
25-^
I 20-
£
pa
I 15
u
10
+J
o
H
/
X
/
/
/
/»
/
/
/ 0/ 2/
/* X
/ / /
// y
/ X
o /
/*
-1 1 1
10 15 20
^0°
® Total CODMn, Eff.
9 O Soluble CODMnj Eff.
1 : l Line
1 1 r~
25 30 35
5
Soluble CODMn of Influent (mg/£)
Fig. 4.18 Corelation between Total or Solube CODMn of Effluent and Solube CODMn of Influent
-------
INJ
o
25 -J
20 -J
3
D
O
o
O
CO
15 -J
10 -J
I
10
I
15
20
25
30
Total CODMn of Effluent
F\g. 4.19 Corelation between Total CODMn and Soluble
CODMn of Effluent
-------
CHAPTER 5. LIME PRECIPITATION AND RECOVERY OF CALCIUM
CARBONATE
5.1 Results of Precipitation 206
5.1.1 Lime Slaking 206
5.1.2 Results of Lime Sedimentation Tank Operation 207
5.1.3 Phosphorus Resolubilization from Floe Containing Phosphorus
5.2 Experiment on Scale Formation of Calcium Carbonate
5.3 Recovery of Calcium Carbonate from Lime Sludge. . ., 210
5.3.1 Results by Centrifuge 2l°
5.3.2 Results of Recarbonation of Lime Sludge 212
5.3.3 Summary 213
205
-------
5. LIME PRECIPITATION AND RECOVERY OF CALCIUM CARBONATE
The results of lime precipitation at the Yokosuka Pilot Plant were reported at
the Third U.S.-Japan Conference on Sewage Treatment Technology. This report is a
summary of experimental results after the Conference. These experiments have the
following three points which are different from former ones:
a. Quick Lime instead of slaked lime is used for making lime slurry.
b. Rapid mixing tank, flocculation tank and lime sedimentation tank are
connected by open channels instead of piping. Before the modification, due to
scaling of calcium carbonate in piping, roughness increased and cross sectional
area decreased, and thus, water levels in tanks became high, and sometines
causing overflow of water from tanks.
c. Sludge thickener and centrifuge are added.
5.1 RESULTS OF PRECIPITATION
5.1.1 LIME SLAKING
Lime slaking is performed as follows: powder quick lime (residue on a 88-
micron mesh sieve is less than 5%) is stocked in the hopper; a fixed quantity of
quick lime is continuously raked out with a volumetric feeder mounted at the
bottom of the hopper; the quick lime is sent to the slaking tank by a screw
conveyer; the water level in the slaking tank is kept constant by a hold-up valve.
Under the conditions of this experiment, i.e., 9m3/h of influent flow, SOOmg;
Ca(OH)2/l of lime dosage and 10% of the concentration of lime slurry, the
retention time in the slaking tank is 60 minutes. Problems in slaking operations so
far are summed up as follows:
a. Average pH value after lime is added to sewage was 10.3 during the period that
slaked lime was used and 10.5 during the period slaked quick lime was used
(Ca(OH)2 dosage, SOOmg/1). From this, it is considered that use of slaked
quick lime creates no problem in terms of pH values.
b. Impurities contained in quick lime (almost all of them is sand) accumulate in
the slaking tank. Purity of quick lime is about 95%. Because of this, clogging of
the lime slurry feed pump occurred. Therefore, the slaking tank is drained once
a day. Drained slurry is returned to the rapid mixing tank.
c. The bottom of the quick lime hopper slants 45 degrees and is connected to the
volumetric feeder. This slanting and a vibrator were provided in an attempt to
prevent bridge of quick lime in the hopper but they were not sufficient. The
vibrator caused quick lime to drop in bulk at a time, thereby changing the
apparent specific gravity of quick lime being supplied to the volumetric feeder.
To avoid this, once every two hours, a stick is used to poke the hopper from its
upper portion to prevent bridge.
d. Calorific value when quick lime is slaked is 15.5kcal/g.mol. Under the
above-mentioned conditions for slaking, temperature rise of 21°C is expected
in the slaking tank. Thus, if water supply to the slaking tank is suspended due
to some reasom or other, only quick lime accumulates in the tank and tempera-
206
-------
ture in the tank goes up. To prevent this a teperature warning device is provid-
ed in the slaking tank, which acts to suspend supply of quick lime when the
temperature reaches 65°C. But thus far this device has not given a warning:
temperature increase of lime slurry flowing out of the slaking tank has been less
than 10°C.
5.1.2 RESULTS OF LIME SEDIMENTATION TANK OPERATION
Table 5.1 shows average values of the results of the lime sedimentation tank
operation during the period between November, 1973 and March, 1975. Under the
operational conditions which are also indicated in the Table, the settling efficiency
of the sedimentation tank did not show significant changes. Therefore, from April,
1975, the conditions have been changed as follows: FeCl3 = 0 to 5.0mg/l in terms
of Fe; return sludge ratio = 0 to 30%; anionic polymer dosage = 0 to l.Omg/1; and
overflow rate = 10 to 100m3/m2.d. Also, a shallow setting device will be insta-
led. Effects of these changes will be examined. Table 5.2 shows data obtaned up to
now. From these data, it seems that additions of Fe, and polymer and
relurn of sludge do not contribute to improvement in the removal of suspended
solids. But it is observed that through return of sludge the concentration of
dissolved phosphorus in overflow from the lime sedimentation tank decreases,
thereby reducing the phosphorus concentration.
5.1,3 PHOSPHORUS RESOLUBILIZATION FROM FLOC CONTAINING
PHOSPHORUS
From 9 a.m., August 20 to 9 a.m., August, 21, 1974, a 24-hour survey
was conducted at the Yokosuka Pilot Plant, at the lime dosage of 300mg
Ca(OH)2/l. As a result, the phenomenon of phosphorus resolubilization from
phosphorus-containing floe that is carried over from the sedimendation thank
was confirmed.
Table 5.3 shows average values of pH of effluent from each unit process,
phosphorus concentration and dissolved phosphorus concentration that were
obtained in this survey. As seen in the Table, while the concentration of
phosphorus in the effluent from the lime sedimentation tank is 0.514mg-p/l,
dissolved phosphorus concentration is 0.044mg/l, only about 8% of total
phosphorus. But as sewage flows down through ammonia stripping,
recarbonation and filtration, the percentage of dissolved phosphorus in
phosphorus increases sharply, 44%, 90% and 99%, respectively and dissolved
phosphorus, which is 0.044mg-p/l in overflow from the lime sedimentation
tank, becomes 0.350mg-p/l in effluent from filter, about 8 times of the
former. It is considered that this is because decrease in pH values in the
processes after the sedimentation tank causes resolubilization of phosphorus
from floe containing phosphorus that is carried over from the sedimentation
tank.
To confirm this phenomenon, the following experiment was conducted.
About 5mg/l of KH2PO4 as P was added to distilled water to make acid
solution of orthophosphate; 200mg.Ca(OH)2/l of lime was added to this
orthophosphate solution and the mixture was mixed for 10 minutes. After mixing,
207
-------
pH was lowered using hypochloric acid. Imediately after pH ajustment, the solution
was again mixed and samples were taken. Samples were also taken 90 minutes and
180 minutes after pH adjustment with keeping the sotution mixed. pH and dissolved
phosphorus of these samples were analyzed and the results are shown in Fig. 5.1.
The Figure indicates that phosphorus is resolved as pH is lowered and that resolu-
bilization occurs in a short period of time.
As stated in the above, in the lime treatment system consisted of lime
precipitation — (ammonia stripping) — recarbonation — filtration, phosphorus is
resolubilized as pH decreases from floe containing phosphorus that is carried
over from the lime sedimentation tank. If two-stage recarbonation is applied,
non-dissolved phosphorus may settle more in the calcium carbonate
sedimentation tank. However, it is a reasonable assumption that pH of the
influent to the calcium carbonate sedimentation tank is 9.5 to 10.0, in which
range pH of the effluent from the ammonia stripping tower falls as shown in
Table 5.3. The dissolved phosphorus concentration in the ammonia stripping
tower effluent was 0.181mg-p/l, which is about four times higher than that in
the effluent from the lime sedimentation tank, i.e., 0.044mg-p/l. Thus, not
only when single-stage recarbonation is employed but also when two-stage
recarbonation is applied, the dissolved phosphorus concentration in the filter
efflueut becomes higher than that in the effluent from the lime sedimentation tank,
it there exists floe contatining phosphorus carried over from the lime sedimentation
tank. Therefore, there arises the possibility that phosphorus removal capacity of
lime precipitation is not displayed sufficiently.
To prevent this, two measures are now being examined:
a. Method for improving the removal of suspended solids in the lime
sedimentation tank
See 5.1.2.
b. System in which effluent from the lime sedimentation tank is directly
filtered and floe carried over is removed, and then water is introduced to
such processes as ammonia stripping and recarbonation.
The latter method might have a problem: calcium carbonate scale is
produced in the media, etc. in the filter and interferes operation of the filter.
Taking this problem into consideration, and on the basis of observations as to
forming of calsium carbonate scale stated in Section 5.2, the following experi-
ments on direct filtration of the effluent from the lime sedimentation tank are
schemed.
a Study on receiving methods of influent to the filter to prevent scale
forming; contact between influent and air is avoided as much as possible.
b Study on the constitution of filtration media.
c Study on filter washing period, pH of washing water and washing rate.
208 -
-------
5.2 EXPERIMENT ON SCALE FORMATION OF CALCIUM CARBONATE
The fallowings are the summary of observations so far obtained at the
Yokosuka Pilot Plant as to scale produced in the lime precipitation process:
a. 90% of the scale is calcium carbonate.
b. Quantity of scale formation in a lower temperature is more than that in a
higher temperature.
c. Scale in the earlier stage of formation is relatively soft and can be removed by
flashing of water.
d. As a results of experiments with stainless steel, steel, rubber, PVC and wood
placed in the rapid mixing tank, the lime sedimentation tank and the lime sedi-
mentation effluent holding tank, difference in materials has little effect on
scale formation (Refer to Table 5.4).
e. Quantity of scale formation was greater in the lime sedimentation effluent
holding tank in which effluent from the lime sedimentation tank falls down
together with air than in the lime sedimentation tank. Quantity of scale forma-
tion in the former was 2 to 1 times more than that in the latter (See Tables
5.4 and 5.5).
f. Quantity of scale began to increase sharply after 10 days (See Table 5.5).
- 209
-------
5.3 RECOVERY OF CALCIUM CARBONATE FROM LIME SLUDGE
At the Yokasuka Pilot Plant, in order to recover calcium carbonate in lime
sludge for reuse of lime, two processes were examined; one was that lime sludge is
put into a centrifuge for selective recovering of calcium carbonate contained in lime
sludge into dewatered sludge, and the other was that lime sludge is put to recarbona-
tion in order to refine the purity of calcium carbonate by dissolving away impurities.
The raw sewage running into the Shitamachi Sewage Treatment Plant, in
Yokosuka in which the pilot plant is constructed contains sea water, and accordingly
is rich in magnesium ions, seriously affecting lime treatment.
Magnesium ion is precipitated as magnesium hydroxide, which are highly
detrimental to settlability, thickening rate and dewaterability of sludge.
Therefore, of the experiments discussed here, the centrifugal dewatering was an
example of low efficiency, and recarbonization of lime sludge an example of so
much high efficiency as magnesium hydroxide was abundant.
5.3.1 RESULTS BY CENTRIFUGE
a) Results of laboratory tests
The thickened lime sludge obtained from the Yokosuka Pilot Plant was de-
watered in a laboratory centrifuge, and thus the dewatered sludge was separat-
ed into three layers as shown in Fig. 5.2.
Layers were taken out one by one, and dried. After a drying, their specific
gravity, and grain size distribution were measured: the specific gravity and grain
size were recorded largest in the lower layer, followed by medium layer and
upper layer in turn. (See Figs. 5.2 and 5.3). The analytical results of composi-
tion of each layer are shown in Table 5.6.
According to Table 5.6, about 83% of calcium carbonate in the thickened lime
sludge is concentrated in the lower layer, and the ratio of calcium carbonate in
the dry sludge is increased up to 75.3% in the lower layer as against 60% in feed
sludge. On the other hand, in view of the reuse of lime, the impurities of
Mg(OH)2, Fe(OH)3, and Cas (OH)(PO4 )3 are increasing more and more, the
higher the level becomes; in the lower layer, impurities are about 50% of those
in the top or middle layer. Also, the lower the layer, the smaller the water
content in the sludge.
Hence, the following conclusions are reached.
1) Lime sludge dewatered by the laboratory centrifuge is separated into three
layers. This is because the specific gravity and grain size in the bottom
layer are larger than those in the top and middle layers.
2) Taking the lime sludge as being composed of calcium carbonate and im-
purities, there is tendancy that calcium carbonate concentrates in the
bottom layer, while impurities are concentrated in the top and middle
layers.
3) The water content in the bottom layer is smaller as compared with that in
the top and middle layers.
In short, calcium carbonate in the lime sludge is inferred to have larger grain
210
-------
size and larger specific gravity than impurities and to be excellent in dewater-
ability.
The selective recovery of calcium carbonate by means of centrifuge is based on
this principle; the bottom layer shown in Fig. 5.2 is taken out as dewatered
sludge, and impurities are conveyed into supernatant. In this way, relative pure
calcium carbonate is concentrated as much as possible into dewatered sludge
and at the same time the sludge is dewatered.
b) Results of tests using the centrifuge for the pilot plant
The centrifuge used for the tests is the modified one for the tests which is the
smallest, available in the market primarily for sewage sludge dewatering pur-
poses, (standard sludge feed rate: 1 m3/hr)
Its specifications are as follows.
Bowl diameter: 2000 (mm)
Bowl speed: 0 ~ 6,000 rpm
Centrifugal force: 0 ~ 4,000 G
Sludge feed rate: 0 ~ 1.85 m3 /hr
Converyor revolution: Variable (by stepless speed changer)
Pool depth: No. 1 (0.5 ~ 0.8 mm), No. 2 (1 - 1.6 mm),
No. 3 (1.5- 2.4mm)
The lime sludge used for the tests was the thickened sludge taken from the
thickening tank in the pilot plant. Its characteristics, are shown in Fig. 5.4.
For the tests, one out of the four factors—sludge feed rate, centrifugal force,
pool depth and conveyor revolution—was taken as a variable while all the
others were fixed constant. In this way, the effects of each factor upon the
ratio of CaCCb captured as dewatered sludge, ratio of CaCCh in dried sludge,
and water content of dewatered sludge were investigated. The test results are
shown in Fig. 5.4.
The following are found from Fig. 5.4.
1) By increasing the sludge feed rate, the absolute volume of CaCOs which is
larger in settling rate than impurities can be increased, improving the
purity of CaCCh and decreasing the water content so much. But the
capture of CaCOs gets lowered.
2) By increasing the bowl speed, settling rate of solids in the feed sludge
toward bowl and the density of sludge deposited on the bowl can be in-
creased. But the relative velocity of CaCOs to impurities remains un-
changed. Accordingly, the capture of CaCOa increases, and the water
content in the dewatered sludge decreases. But the purity of CaCOs re-
mains unchanged.
3) Pool depth corresponds to the scraping-out depth of dewatered sludge. In
the tests, if there are strata as shown in Fig. 5.2, it may be theoretically
agreed that the water content of dewatered sludge can be decreased, and
the ratio of CaCOs in dewatered sludge can be increased without changing
the capture of CaCOs largely if the pool depth is adjusted to the depth
falling just on the boundary surface between the middle and bottom
- 211 -
-------
layers shown in Fig. 5.2. It is inferred that in the tests the pool depth was
located above the boundary surface between the middle and bottom
layers.
4) By increasing the conveyor speed, the detention time of sludge deposited
on the bowl is shortened as sludge is discharged quickly one after another.
Eventually, therefore, the pool depth is considered likely to become larger.
Hence, it is concluded that to increase the conveyor speed is to increase
the pool depth.
To generalize the results within the scope of the tests, the centrifugal force
should preferably be set at 3,000 G and the pool depth at No. 1 (0.5 ~ 0.8
mm) and the conveyor speed at 4.7 rpm. in order to obtain dewatered sludge of
low water content and with high capture of calcium carbonate of high purity
from lime sludge.
The sludge feed rate, when increased, increases the purity of CaCCb in the
dewatered sludge, but decreases the capture of CaCCb to the contrary. Further
investigations are needed in this respect for the purpose of finding out the
optimum conditions. The centrate contains a considerably large amount of
solids (9,200 mg/lit. to 13,500 mg/lit. in the tests) as part of solids in the
thickened sludge is transfered into the centrate. For this reason, the solids in
the centrate are required to be dewatered and separated. The results of
dewatering test on the centrate by means of the pilot plant centrifuge are
shown in Table 5.7. The centrate was hard to dewater; even when the cen-
trifugal force was increased up to 3,000 G, the capture of solids was only 47.3
% with the water content left as high as 84.8%. Thus, the centrate of centrate
still contained no less than 6,500 mg/lit. of solids. Namely, sharp increase in
the capture of solids is hardly expected unless chemical dose is practised.
Use of dewatering aid, such as polymer, or practice of alternative method will
be necessary.
5.3.2 RESULTS OF RECARBONATION OF LIME SLUDGE
Precipitation rates of CaCCb , Mg(OH)2, Cas (OH)(PC>4)2 , which are main com-
ponents of lime sludge, are increased with rise in pH value, and they are solubilized
when pH value declines. If the solubilizing rate of CaCCb is smaller than that of
Mg(OH)2 and Cas (OH)(PC>4 )3 , recarbonization of lime sludge can improve the
purity of CaCCb in the lime sludge, it will provide an effective way for the reuse of
lime sludge. Then, the recarbonation of lime sludge was,tested at the Yokosuka
Pilot Plant, with the results shown in Fig. 5.5
According to Fig. 5.5, it is found that Yokosuka Pilot Plant's lime sludge used
for the tests has smaller solubilizing rate of CaCCb with reduction in pH than
Mg(OH)2 's and Cas (OH)(PO4 )3 's, and therefore that it is feasible to recarbonate the
lime sludge. By recarbonating feed lime sludge from pH 11.29 to pH 8.11, CaCCb
was solubilized 16%, and Mg(OH)2 and Cas (OH)(PO<. )3 82% and 30%, respectively.
In that case, the composition in dried sludge changed as shown in Fig. 5.6;
while CaCCb accounted for 56.9% in raw lime sludge, it increased up to 72% after
recarbonation. On the other hand, Mg(OH)2 changed from 22.8% to 6.1%.
212
-------
5.3.3 SUMMARY
In order to effectively recover lime from the lime sludge, it is necessary to re-
cover majority of calcium carbonate, the material of lime, with high purity and with
less water content in dewatered sludge, from the lime sludge in a preliminary stage.
As ways to this end, the centrifuge method and the recarbonation method were
examined, and the following conclusions are attained.
1) Calcium carbonate contained in lime sludge is larger in grain size and specific
gravity than impurities such as magnesium hydroxide and calcium hydro-
xyapatite, and is excellent in dewaterability.
When lime sludge is put to centrifugal separation process, calcium carbonate is
trapped selectively in the bottom layer. By recovering the bottom deposit in
the form of dewatered sludge, the above objective is achieved.
2) There are four factors influential to the centrifugal separation. They are sludge
feed rate, centrifugal force, pool depth and conveyor vevolution. All these have
effects on the purity and capture of calcium carbonate and water content of
dewatered sludge.
3) The optimum conditions in this test condition under which to operate the
centrifuge for dewatering lime sludge to recover lime are: centrifugal force,
3,000 G; pool depth, No. 1 (0.5 ~ 0.8 mm); conveyor speed, 4.7 rpm. As
regards the sludge feed rate, further investigations are required.
4) Solids in the centrate are hard to recover without chemical injection by cen-
trifuge. It is therefore necessary to study alternative methods.
5) As regards the lime sludge used in the tests, recarbonization improves purity of
calcium carbonate without degrading its capture.
213 -
-------
Table 5.1 Results of Lime Precipitation (Average of 1973 ~ 1974)
Experiment Conditions Lime Dosage 300 mg-Ca(OH)2/£
Overflow Rate of Lime Sedimentation Tank: 33 ~ 50 m3/m2-day
Polymer Dosage: 0 ~ 0.2 mg/£
Return Sludge Rate: 0 ~ 20%
Influent (secondary effluent)
Effluent from lime sedimenta-
tion tank
Removal (%)
pH
7.24
10.53
-
Turbidity
(mg/£)
4.6
12.2
-
S S
(mg/fi)
4.1
19.5
-
P
(mg/£)
1.464
0.326
77.7
P, ortho
(mg/£)
1.265
0.262
79.3
BOD
(mg/£)
8.41
5.22
37.9
CODcr.
(mg/£)
31.9
25.4
20.3
214
-------
Table 5.2 Results of Lime Sedimentation Tank Operation
Lime Dosage: 300 mg-Ca(OH)2/C
Overflow Rate of Lime Sedimentation Tank: 50m3/m2-D
^^"^^^^ Condition
Item ^^^^^
Temp, of influent (°C)
PH
SS (mg/C)
P (mg/fi)
P-D (mg/C)
© *
@**
©
©
(D
©
©
©
Fe+++ addition (mg/fi)
0
18.7
7.20
10.23
22.8
18.5
1.487
0.313
0.836
0.151
0.5
19.5
7.34
10.26
24.0
16.0
1.906
0.417
1.331
0.189
2.0
20.5
7.24
10.31
31.0
10.2
3.320
0.436
2.265
0.209
5.0
19.9
7.28
10.28
27.0
55.2
2.054
0.276
1.666
0.120
Return sludge (% to influent flow)
0
22.0
7.24
10.21
9.4
13.0
2.538
0.472
1.882
0.277
10
21.3
7.29
10.24
11.6
23.2
1.709
0.213
1.226
0.074
20
21.0
7.22
10.29
16.8
31.6
2.170
0.287
1.569
0.094
30
22.2
7.42
10.13
37.0
26.4
2.020
0.345
1.297
0.104
Polymer additon (mg/£)
0
24.5
7.46
4.3
21.6
1.895
0.452
1.155
0.287
0.1
24.6
7.26
10.35
11.7
27.0
1.864
0.403
1.647
0.163
0.5
24,8
7.36
9.31
25.0
40.5
1.116
0.182
0.649
0.104
to
h-'
* ® Influent (Secondary effluent) ** © Effluent from lime sedimentation tank
-------
Table 5.3 pH, Phosphorus (P), and Dissolved Phosphorus of Each Unit Process Effluent
Influent (secondary effluent)
Effluent from lime sedimentation
tank
Effluent from ammonia stripping
effluent
Effluent from recarbonation tank
Effluent from filter
PH
7.24
10.35
9.89
7.47
6.92
P (mg-P/£)
1.554
0.514
0.408
0.337
0.352
P-D (mg-P/J2)
1.511
0.044
0.181
0.304
0.350
P-D/P
0.972
0.081
0.444
0.902
0.994
216
-------
Table 5.4 Materials for Lime Precipitation Process and Scale Formation
Water temp.: about 14°C
pH: about 10.4
^~~"--\^^ Material
Setting place~""""~-\^^
Rapid mixing tank
Lime sedimentation
tank
Lime sedimentation
tank effluent Holding
tank
Stainless
steel
66.1*
5.2
19.6
Steel
68.4
6.1
22.2
Rubber
67.8
6.8
17.1
P.V.C.
71.7
5.9
23.7
Planed
wood
62.2
6.6
18.2
Wood
70.2
1.5
22.1
* Scale weight (mg)/area of test piece (cm2) after 30 days from test piece setting.
217
-------
Table 5.5 Results of Scale Formation of Calcium Carbonate Experiment
(Water temp.: about 13°C pH: about 10.4)
Place putted test place
10cm lower from water surface
of lime sedimentation tank
10cm lower from water surface
of lime sedimentation tank
effluent holding tank
Days passed after test piece putted (D)
o
0.075
0.503
6
0.316
0.645
8
0.347
1.587
10
0.603
4.040
15
1.489
7.695
Scale weight (mg)/area of test piece (cm2)
218
-------
Table 5.6 Separation Results of Lime Sludge by Centrifuge for Laboratory
3,000rpm 10 minutes
Results of
analysis
Rate of each
component in
dry sludge (%)
Rate of each
component
captured in
each layer
(%)
Ca (mg/g)
Mg (mg/g)
Fe (mg/g)
P (mg/g)
VSS (mg/g)
Specific gravity
Water content (%)
CaC03
Mg(OH)2
Fe(OH)3
Cas(OH)(P04)3
VSS
The others
Solids
CaC03
Mg(OH)2
Fe(OH)3
Cas (OH)(P04)3
VSS
The others
Feed sludge
255
69.2
3.34
14.4
181
2.250
89.5
60.0
16.6
0.6
7.8
13.0
2.0
Dewatered sludge
Upper layer
167
138
5.58
37.2
284
2.076
89.0
27.1
33.0
1.1
20.1
18.2
-
20.6
9.5
39.0
35.9
51.3
36.2
Medium layer
186
122
5.50
26.9
259
2.093
82.7
32.1
29.2
1.0
14.5
16.9
4.3
14.6
7.9
24.5
23.1
26.2
23.8
Lower layer
313
41.0
1.98
5.17
94.4
2.276
57.4
75.3
9.8
0.4
2.8
6.4
3.3
64.8
82.6
36.5
41.0
22.5
40.0
219
-------
Table 5.7 Results of the Second Stage Dewatering
Caracter of the First Stage Centrate
SS: 11,800 mg/e Fe: 20.5 mg/g-dry sludge
Water Content: 98.8% P: 19.7 mg/g-dry sludge
Ca: 105 mg/g-dry Sludge VSS: 330 mg/g-dry sludge
Mg: 132 mg/g-dry Sludge
Dewatering
condition
Results of dewatering
Centrifugal force (G)
. Sludge feed rate (m3/h)
Conveyer revolution (rpm)
Pool depth
Water content (%)
Rate of each component
captured in dewatered sludge
(%)
Solids
Sludge volume
CaC03
Mg(OH)2
Fe(OH)3
Cas(OH)(P04)3
vss
The others
1
1,000
0.917
6
3
81.3
26.1
1.1
81.0
36.6
27.9
32.6
42.6
61.1
2
2,000
0.798
6.7
3
83.3
37.5
2.2
86.6
49.7
42.9
45.2
51.5
66.7
3
3,000
0.822
8.1
3
85.3
40.5
2.7
84.1
57.5
52.1
53.6
60.4
55.6
4
4,000
0.895
9.4
3
84.8
47.3
3.2
87.6
59.3
55.5
55.7
63.9
67.6
220
-------
6-,
5.
4-
|2H
1-
Dissolved Phosphorus in Influent
O 0 minute after pH adjustment
9 90 minutes after pH adjustment
• 180 minutes after pH adjustment
x Lime treated water
10
11
PH
Fig. 5.1 pH Lowering vs. Resolublization of Phosphorus
- 221 -
-------
Centrate
! I I I I I
De watered
/ / /
Sludge/
Centrifuge Tube
^ Upper Layer
Specific Gravity = 2.076
Medium Layer
Specific Gravity = 2.093
Lower Layer
Specific Gravity = 2.276
Fig. 5.2 Result of Lime Sludge Centrifugal Separation
222
-------
100 T
90-
55
1UU-
80-
g- 60-
^
£ ,A
.3 40-
o
>
20-
/ Upper Layer
/7l
iS
\
\
\
\
\
\
\
\
\
\
:HI
^r- Medium Layer
/• Lower Layer
if
L
j~j
K 1 IrTll,-, n |~|
20
40 ~ 60 ~ 80
(Grain Diameter
100
20 40 60 80 100 12Q 140 160 180 200 220
(Grain Diameter (^))
Fig. 5.3 Grain Size Cure of Each Layer
223
-------
100 ,
90
80
70
60
50 C
40
30
20
10
0
i "• — -£ -^ Rate of CaCO3 Captured in Dewatered Sludge
\ Rate of Total Solids
^ *f Captured in Dewatered Sludge
XAI^*^ ^~ Water Content of Dewatered Sludge
_ speed Sludge ^*a5;^— _ _ _^^ A -o—
^°— r""0' ° *~
^ ^" ' Rate of CaCO3 in Dry Dewatcred Sludge
Experiment Condition (A series)
Centrifugal Force: IOOOG
Conveyer Revolution: 6 rpm
Pool Depth: 3
100
90
80
70
60
50
40,
30
20
10
Oi
:^
- ?—*- A A
" /' ^^^^
- /'
. / . o 0
V
k
/ Experiment Condition (B series)
1 Sludge Feed Rate: 0.81 2 r
/ Conveyer Revolution: 6—8 rp
/ Pool Depth: 3
J
0.4 0.8 1.2 1.6
Sludge Feed Rate(m3/n)
2.0 0 1000 2000
Centrifugal Force (G)
3000
100 -I
90 -
80 -
70
60
g50
40
10
100
90
X—
Caractcr of Feed Sludge
Water Content: 94.5%
Rate of CaC03 in
Dry Sludge: ' 53.4%
60-
40 •
Experiment Condition (C series)
Centrifugal Force' IOOOG
Sludge Feed Rate. 0.838 -0.923 m3/h 30
Conveyer Revolution. 6 rpm
20
10 •
0
1 2 3
(0.5-0.8mm) (1-1.6mm) (1.5~2.4mm)
Pool Depth
Experiment Condition (D series)
Centrifugal Force: IOOOG
Sludge Feed Rale: 0.838 ~ 0.894 m3/h
Pool Depth: 1
0 S 10
Conveyer Revolution (ipm)
Fig. 5.4 Dewatering Results of Lime Sludge by Centrifuge for Pilot Plant
-------
- 5
0
X
32
DO x
o •—
'' n
x O
"— O
OO co
C/3 O
Cas(OH)(P04)3
CaC03
12 11 10 9 ;
PH
Fig. 5.5 pH Reduction and Each Component Change of Lime
Sludge by Recarbonation
225
-------
0
20
40
60
80
100
[;ced Sudge
(pH = 11.29,SS = 25.3g/2)
Recarbonation Sludge
(pH = 8.11,SS = 16.8g/£)
.
1 '
CaC03
Nv^OH
"ca
1
1
\=
1 The Others
(JQH)(P04)3
Fig. 5.6 Rate of Component in Feed Sludge and Recarbonation Sludge
226
-------
CHAPTER 6. ADSORPTION BY ACTIVATED CARBON AND REGENERA-
TION OF SPENT CARBON
6.1 Adsorption Studies by Granular Activated Carbon 228
6.1.1 Outline of Experiment Facilities 228
6.1.2 Conditions of Experiment 228
6.1.3 Results of Adsorption Experiments 228
6.2 Regeneration of Granular Activated Carbon 232
6.2.1 Introduction 232
6.2.2 Reactivation by Multi-Hearth Furnace 232
6.2.3 Arrangement for Experiment . 232
6.2.4 Experiments 234.
6.2.5 Measuring Items and Methods of Measurement 234
6.2.6 Regenerating Conditions 235
6.2.7 Results of Regeneration ^35
6.2.8 Summary ,237
6.3 Laboratory Regeneration Test of Granular Activated Carbon .... . ..239
6.3.1 Introduction 239
6.3.2 Laboratory Equipment Used. . .... 239
6.3.3 Testing Method 239
6.3.4 Results of Tests .240
227
-------
6. ADSORPTION BY ACTIVATED CARBON AND REGENERATION OF
SPENT CARBON
6.1 ADSORPTION STUDIES BY GRANULAR ACTIVATED CARBON
6.1.1 OUTLINE OF EXPERIMENT FACILITIES
Kyoto Pilot Plant is equipped with six contact column using granular activat-
ed carbon. They are paired off into three groups, permitting three tests at the same
time.
Flow diagram of the process is as illustrated in Fig. 6.1. The dimensions and
other particulars are as follows.
Dimensions: surface area, 0.76 m x 0.93 m = 0.7 m2
allowable maximum head loss, 5.0 m
Media support: Leopold block, gravel layer (25 cm)
Washing: back washing and surface washing in com-
bination
Processing capacity: maximum overflow rate, 600 m3/m2/d.
(17.5 m3/hr/column)
The characteristics of activated carbon charged into the column are as listed in
Table 6.1.1.
The colum are so pipe harnessed as to permit other three running modes
single-column 6-group, 3-column 2-group, and 6-column 1-group.
6.1.2 CONDITIONS OF EXPERIMENT
In the adsorption experiment, column have been operated for some 12 months
or around 35,000 m3 in terms of the volume of wastewater passed through per
0.7 m2 after being charged with fresh carbon and for some 6 months or 13,000 m3
in the volume of wastewater after regeneration of carbon.
As regards the fresh carbon, LV 10 m/hr has been taken as standard. As regards
the regenerated carbon, the contact time has been fixed at 18 min. per column, and
LV has been set at around 9.4 m/hr, a little lower than fresh carbon, to meet the
decrease of bed depth due to regeneration loss. Wastewater flow in the column is
downward.
For the adsorption experiment the filtered secondary effluent obtained from
the Toba Sewage Treatment Plant has been used. In filtration, A12(SO4)3 has
occasionally been dosed at a rate of about 0.65 — 1.96 mg/1 as Al. There has been
practised no particular flocculation sedimentation to speak of, so majority influent
for the experiment may be said to be simply filtered secondary effluent.
The influent flow down through the column gravitationally, and its SS gradual-
ly blocks up carbon bed, decreasing actual LV
In order to avoid this, the primary column has been put to back washing about
once every three days. Backwash flow rate has been set at 0.74 to 0.9 m3/m2/min,
though different slightly dependent on the columns.
6.1.3 RESULTS OF ADSORPTION EXPERIMENTS
The results of experiments so far conducted show that the adsorption effect
228
-------
is slightly different with the kind of carbon. And the carbons have much in common
from the view point of time-dependent patterns.
The discussion here is therefore referred to Brand-A (8 x 30) for the secular
change and to the data obtained in 1975 (regenerated carbon) for the differences
due to difference in quality of carbons.
(1) Removal of organic matter
Secular changes of indices for organic matter - BODS, CODMn and TOC -
are shown in Figs. 6.2 through 6.4. As is clear from these figures, the organic matter
removal capacity of activated carbon is not so high rather than which we expected.
BOD5 : -
Removal of ordinary BODS by fresh carbon is small. Worse, it sometimes runs
by contraries; there are many such cases as BODS becomes the worse by the
adsorption treatment with activated carbon.
In many cases, the effluent of the secondary column has larger BODS value
than that of the primary column. In the case of regenerated carbon, the removal
is about 75% at the beginning of restart. After one month operation however, it
declines to 30%.
As regards the fresh carbon, BODS value is larger in the effluent of secondary
column than in the effluent of the primary column, all the way from the beginning
of operation.
This rise of BOD5 value in the effluent of the secondary column was suspected
to be attributable to the promotion of nitrification in the bed of activated carbon,
and studies were made in this respect accordingly.
Fig. 6.5 shows BODS and forms of nitrogen in influent and contactor column
effluents, which are based on the data obtained in May 1975.
On May 8, BOD5 in the effluent of the secondary column was smaller than in
the effluent of the primary column. On May 29, the situation was reversed. BOD5
were measured at once in ordinary method and in a special method in which
nitritying bacterias were suppressed. BODS by the former method is named
T-BODS, and that by the latter C-BODS. From Fig. 6.5, the following are noticed.
(A) The larger the change of NO3-N, the more reasonable the decrease of T-BODS.
If the change of NO3 -N is small, T-BOD5 is inverted.
(B) Even when T-BODS is inverted, C-BODS decreases reasonably.
In additions to these facts, decreae of DO is also noticed. Also, various bacteris
are identified in the activated carbon contactor column. Hence, inhabitation of
nitrifying bacteria in the column permits of no doubt. It is therefore judged that
the increase of T-BOD5 is due to nitrification. In support of this, the pilot studies
conducted by the Bureau of Water Works. Tokyo Metropolitan Government, for the
production of industrial water from wastewater revealed lots of nitrite-forming
bacteria and nitrate-forming bacteria present in the effluent of activated carbon
contactor column.
In view of these facts, use of T-BODS as a characteristic to provide a guideline
for activated carbon treatment will be disagreed. In order to remove T-BOD5 which
- 229 -
-------
has been taken up as an index for organic matter in the Environmental Water
Quality Standard and the Effluent Limitations Guidelines in Japan, the treatment
using with activated carbon should be reviewed.
Both fresh carbon and regenerated carbon show small removal of CODMn con-
trary to our expectation. Even at the beginning of operation, fresh carbon remain-
ed at the level of 30% in removal with a contact time of 18 min. (primary column
effluent) and about 70% for a contact time of 36 min. These values were reduced
to 25% and 50% respectively in 1 to 2 months after start-up of operation. The re-
moval thereafter decreased gradually to some 30% even with 36 min. of contact.
This tendency remained the same after regeneration; Only for 2 to 3 months,
50% or more of removal could be attained stably. In the experiments, there was no
dramatic drop in CODMn removal, and it could not be found whether break-through
was developed or not.
No direct measurement of CODMn adsorption capacity was made as to fresh
carbon, but the following was inferred to be according to TOC isothermal adsorp-
tion before and after activated carbon treatment.
(i) From Fig. 6.6, the following equation is derived.
TOC (mg/fi) = 0.889 x COD (mg/8) + 1.748 (1)
Taking the average effluent TOC as 10 mg/1.
as suggested by Fig. 6.4, we obtain COD = 93 mg/1. from Eq. (1).
Namely, at a TOC concentration of around 10 mg/1.,
CODMn 9.3
TOC 10
(ii) TOC Freundrich line of fresh carbon in Fig. 6.14 is given by the following
formula.
x/M = K.C1/n = 0.006.C1'45 (3)
Hence, at TOC 10 mg/1. (This value is over the chart-range), x/M ft
0.169mg/mgft 169 kg/t.
From Eq. (2), this is converted into COD as follows.
169 x 0.93= 157.2 kg/t
(iii) On the other hand, the total, weight of adsorbed matter, L, can be express-
ed by the flow rate, Q, and CODMn concentration difference between influent
and effluent of carbon column (Ci — Co) as follows.
L = 2 (Ci - Co).Q.At
Cumulative total volume of water, V, is given by the following formula.
Thus, Fig. 6.7 is obtained.
(iv) With reference to Fig. 6.6, after treating 34000 m3 of filtered secondary ef-
fluent, fresh carbon removed only 105 kg CODMn in the primary column and
90 kg CODMn in the secondary column. On the other hand, the adsorption
capacity per column is calculated from (ii) as follows.
157.2 kg/t x 0.7 m2 x 3 m x 0.5 t/m3 = 165.1 kg. Namely, the removal is 65%
230
-------
in the primary and 55% in the secondary.
It is therefore considered that this denies the breakthrough of the activated
carbon.
(v) In addition, by backwashing the column, a great quantity of suspended solids
and COD is detected in the backwash wastewater as shown in Figs. 6.8 and
6.9, showing that the activated carbon bed serves not only as an adsorber but
as a filter. For example, the four measurements conducted in the summer of
1974 are as shown in Table 6.2; removal of CODMn in the primary column
by filtration was 0.034 ~ 0.125 kg per 168 m3 of water (0.2 ~ 0.74 g/m3)
(vi) Taking an average CODMn removal of 0.43 g/m3, 34,000 m3 releases 14.6 kg
or 14% of removal by filtration. Namely, the weight ratio of actually adsorbed
CODMn to the capacity is no more than 50% even in the primary column.
For all that the breakthrough is theoretically denied as above, why CODMn
removal is extremely low.
The following may be suspected to be.
@ CODMn lacks eligibility for organic matter index.
<3) Influent is anomalous in quality.
As regards @, however, TOC removal is much of a muchness, and should be
deleted. As regards (3), the influent used for the experiments was filtered secondary
effluent of activated sludge process.
The influent applied to the activated carbon adsorption process which usually
raises 90% or more efficiency is always put following to chemical coagulation, and
effect of the omission of this coagulation process may be a cause. To corroborate
this, we are going to proceed a laboratory experiment. From 1976 on, this will also
be corroborated on a pilot plant scale.
TOC: -
Like CODMn, TOC removal is also low and far from our expectation. In the
case of fresh carbon, the removal is below 50% inclusive of the secondary column
from the beginning of operation, which is worse than CODMn removal.
In the case of regenerated carbon, the removal is more than 50% at the be-
ginning with 36 min. of contact, but is still far less on the whole. Because we lack
satisfactory data we can not make any analysis like as Fig. 6.7. Just as with CODMn
however, the breakthrough is unlikely.
This low removal will be ascribable to the peculiarities of the influent employ-
ed.
(2) ABS removal
Application of activated carbon to water and wastewater treatment is to re-
move organic matter, deodor, remove colouring matter and also to remove ABS.
The pilot plant experiment discussed here placed emphasis to the removal of
organic matter, but also handled ABS removal to some extent. Fig. 6.10 shows an
example.
In the case of fresh carbon, you can find lower removal at the beginning of
operation, fourth month and eight month. But ABS removal is higher and more
- 231 -
-------
stable. Comparing with the removal of organic matter. ABS removal recorded is
around 50% with 18 min. of contact and around 80% with 36 min. of contact. In
the case of regenerated carbon, the removal is even more stable; even after 6 months
from start, the removal remained 90% with 36 min. of contact. But, the removal
with 18 min. of contact plunges to 40 to 50% from about 5th month, and the break-
through is suspected to be.
ABS removal is surprisingly high compared with other items, and this is not
limited to this brand (Brand A), but is seen common to other brands like as
Fig. 6.11. The figure shows the results of measurement made 5 and odd months after
start-up operation using regenerated carbon.
6.2 REGENERATION OF GRANULAR ACTIVATED CARBON
6.2.1 INTRODUCTION
The regeneration is carried out by heating, chemical extraction, oxidation and
decomposition and biodegradation and so forth, depending on the kind of activated
carbon, adsorption conditions and matter to be adsorbed. If liquid-phase adsorp-
tion, like as in sewage treatment is practised, the surface of activated carbon
particles are foued up inversibly and it becomes to be difficult to regenerate.
For this reason, the thermal regeneration (baking reactivation process) is usual-
ly put to practice. Dealt with here are the findings from the experiment on reactiva-
tion of spent activated carbon by multi-hearth furnace.
6.2.2 REACTIVATION BY MULTI-HEARTH FURNACE
The following are the conditions required for the regenerator of spent activated
carbon.
(1) High thermal efficiency
(2) Easy control of zone temperature and atmosphere in drying, baking and acti-
vating processes
(3) Less burning-off in baking and activating stages
(4) Exposing the surfaces of activated carbon particles with high frequency
(5) Easy control of detention time to meet degree of adsorbed weight of matter
(6) Less susceptibility to mechanical failure and wear loss
(7) High capability of covering a wide range of processing rates
(8) Easy operation and maintenance
(9) Established and proven structure as equipment
The multi-hearth furnace employed for the experiment is qualified with re-
spect to the above requirement, and has widely been used.
6.2.3. ARRANGEMENT FOR EXPERIMENT
(1) Specifications of principal equipment
The experiment installation is composed of a furnace, spent carbon feed
system, regenerated carbon withdrawal system, exhaust gas treatment system
and a steam generator.
232
-------
(i) Furnace
Type : 6-hearths type
Dimensions : 750 0 x 1,500 H
Shaft drive : 0.23 - 2.3 rpm, variable, 0.4 kW
Main materials: Steel + refractory
Ancillary : Gas burner x 8 units
equipment
(ii) Steam generator (packaged boiler)
Type : Low-Pressure type
Capacity : 0.5 kg/cm2, 75 kg/hr
Quantity : 1 unit
(2) Arrangement flow for Experiment as per Fig. 6.12.
(i) Spent carbon feed system
Spent carbon is withdrawed from the contact colum in the form of slurry,
put into a dewatering tank where it is dewatered roughly, and then is charged
by the screw conveyor onto the 1st hearth of the furnace at a constant rate.
Here the moisture content of the spent carbon is about 45 to 50%.
(ii) Regeneration method
The spent carbon thus fed, which has a water content of 45 to 50% is heated
at 250 to 950°C in the furnace, and is reactivated after passing through drying,
baking and activating processes.
The furnace is equipped with six hearths and its 2nd, 4th, 5th and 6th stages
are each equipped with two low-pressure velocity gas burners using propane
gas as a fuel.
In order to promote the reactivation, the 4th, 5th and 6th stage are each
equipped with two nozzles supplying steam as an oxidizing gas.
(iii) Regenerated carbon withdrawal system
The regenerated carbon is then discharged from the withdrawal chute equipp-
ed on the 6th stage hearth into a quench tank without being exposed to the
open air and quenched. The quench tank is always supplied with water to keep
its temperature below a specified level. Then, the regenerated carbon is with-
drawed from the quench tank in the form of slurry and dewatered in a dewater-
ing tank.
(iv) Exhaust gas treatment system
The exhaust gas from the furnace contains stinky gas volatilizing at a low
temperature in the drying process, organic gas developed by decomposition
in the baking process and reducing gas from the reactivating process. Also it
contains carbon particulates developed by mechanical grinding in the form of
dust. In order to completedly burn out stinky gas, decomposed gas, reducting
gas and sut carbon, an after-heater is located just behind the furnace.
The after-heater is held at a temperature of 800 to 850°C, and in it the ex-
haust gas is detained for about 0.5 to 1.0 sec.
The exhaust gas treated in the after-heater is then introduced into a scrubber
- 233
-------
where it is cooled and moistened to remove dust and oxidizing gas, and then is
vented to the open air.
6.2.4 EXPERIMENTS
In order to investigate reactivating condition for multi-hearth furnace and
activity recovery rate, some experiments were proceed using the spent carbon from
the Kyoto pilot plant, and pilot scale furnace in December 1974.
6.2.5 MEASURING ITEMS AND METHODS OF MEASUREMENT
(1) Measuring items
Three brands of activated carbon. A, B and C, are to be measured as to the fol
lowing items.
(i) General characteristics
Apparent density, Particle size Hardness number. Fixed residue, Methylene
blue number, Iodine number, Molasses decolorizing index, Phenol value, ABS
value
(ii) Adsorption capacity for organic matter in water
TOC Freundrich isotherms using filtered secondary effluent
(iii) Micropore characteristics
Surface area of micropore per unit carbon weight, mean micropore size, micro-
pore volume, pore size distribution
(iv) Weight of adsorbed matter
(2) Outline of measuring methods especially used in Japan
(i) General characteristics
Phenol value: —
According to JWWAK 113 (Japan Water Works Association Standard: Me-
asuring Method of Powder Carbon for Water Works)
100 ppb phenol solution is taken as a control, and the amount of activated
carbon (ppm) required to reduce it to a concentration of 10 ppb is measur-
ed. This amount is called phenol value.
ABS value: -
According to JWWAK 113.
The amount of activated carbon (ppm) required to reduce the concentra-
tion of an ABS (sodium alkyl benzene sulphurnate) solution from 5 ppm to
0.5 ppm is called ABS value.
(ii) Adsorption capacity for organic matter in water
Filtered secondary effluent was used for measurement sampling from the
Kyoto Pilot Plant on Dec. 23 and 25, 1974. 0.3% and 0.08% powder carbon
suspensions were prepared, and 1.0 ml and 0.5 ml portions were taken re-
spectively and added to 20 ml of control solutions. The mixtures were shaken
for 2 hrs and filtered.
The filtrate was acidified with hydrochloric acid, and dissolved carbon dioxide
was removed by bubbling. Then, TC was measured with a TOC analyzer.
234
-------
Change of liquid volume due to addition of suspension was corrected, and
Freundrich equation was applied to adsorbed weight and residual TOC con-
centration for refining the data.
(iii) Weight ratio of adsorbed matter to fresh carbon
Dry sample of spent carbon was taken lOOg into an electric furnace using
nitrogen gas as atmosphere gas and controlled at 900°C, and was heated for 1.5
hrs. From the resultant weight reduction, the weight rate of adsorbed matter to
fresh carbon was calculated using the following formula.
Weight ratio of adsorbed _ Reduction at 900° C
matter to fresh carbon Yield at 900° C
Components to be deposited and occluded into carbon without volatilization
during the heat treatment at 900° C for 90 min. were neglected.
6.2.6 REGENERATING CONDITIONS
The following are important factors for the reactivation of spent carbon in
the furnace.
(1) Hearth temperature and its distribution
(2) Detention time of carbon in the furnace
(3) Hearth atmosphere
(4) Feed rate of activating steam and its position of feed
(5) Loading rate of carbon
In the test, the maximum hearth temperature was set at 930°C, and the activat-
ing hearths (4th, 5th and 6th stage) were all set at the same temperature.
The detention time was set at 30 min. irrespective of the kind and feed rate
of spent carbon. In order to avoid burning off due to air leakage, the furnace
atmosphere was controlled at +2 to +5 mm H2 O throughout the furnace. O2 % in
each stage was controlled below 0.1% using O2 monitoring meter under any specific
conditions. As regards the feed rate and kind of carbon, the activating stage tem-
perature was changed with the apparent density as a basis which could provide the
fastest mean of judging the recovery rate.
The steam feed was set at 0.6 to 0.9 kg/kg RC; the fourth stage was supplied
some one third and the sixth stage some two thirds. The loading rate was set at 25 to
35 kg/m2 hr. based on wet weight of spent carbon. The operating conditions in
regeneration for these spent carbon and consumption rate of fuel aid, etc. are shown
in Table 6.3.
6.2.7 RESULTS OF REGENERATION
(1) Recovery rate
The recovery rate of spent carbon can be expressed in two ways; one is
gravimetric and the other volumetric. The problem involved in the gravimetric
recovery rate is that the reduction of carbon size due to mechanical and thermal
effects cannot be taken into account in the evaluation of recovery rate.
Another problem is the inorganic matter which is left after regeneration. The
235
-------
recovery rate should be the gravimetric one determined by the measurement of
weight before and after regeneration.
The volumetric recovery rate (A) is shown in Table 6.4. The gravimetric
recovery rate is shown in Table 6.5. The gravimetric recovery rate might possibly
include errors as water content and weight ratio of adsorbed matter to fresh carbon
for calculation were taken at random. By way of reference, volumetric recovery rate
(B) as calculated according to another method is shown in Table 6.6. The test results
showed as high a recovery rate as from 94 to 98%.
(2) Changes in general characteristics
The measurements of general characteristics of fresh, spent and regenerated
carbon are shown in Fig. 6.13. The adsorption capacity of spent carbon was degrad-
ed seriously, particularly in the primary column. Table 6.7 shows the results of heat
treatment at 900°C in a nitrogen gas atmosphere. It is evident from Table 6.7 that
the weight ratio of adsorbed matter to fresh carbon in the primary column is large.
The recovery rate given in Fig. 6.13 denotes the value showing the extent of
adsorption capacity with that of fresh carbon taken as 100. It is calculated accord-
ing to the following formula.
„,. adsorption capacity of regenerated carbon
Recovery rate (%) = , v ,. y— j4—i: c x l °°
adsorption capacity of tresh carbon
Here we define the term "adsorption rate" as the weight ratio of adsorbed matter to
the adsorption capacity of fresh carbon. The adsorption rate on each items obtained
from Fig. 6.13 is shown in Table 6.8.
As is clear from Table 6.8, ABS value is most largest, followed by molasses
decoloring index, and methylene blue number. Usually, the higher the adsorption
rate, the worse the recovery. This is corroborated by the experiment. The apparent
density is reciprocal to the recovery rate. It is therefore conjectured that the
increase of the recovery rate will reduce the recovery rate of apparent density.
(3) Capacity to adsorb organic matter in water
TOC adsorption capacity was measured using filtered secondary effluent. The
results were adjusted by Freundrich equation as shown in Figs, from 6.14 to 6.16.
1/n and K in Freundrich equation are shown in Table 6.4. As regards 7 mg/C and 3
mg/e of residual TOC concentration, the recovery of adsorption capacity was from
73 to 110%.
(4) Micropore characteristics
As to various brands, nitrogen gas adsorption curves were determined accord-
ing to a modified Constone-Inkley method to calculate pore size distribution, and
get a relationship between 10 ~ 300A micropores and their accumulative volume.
Also, the relationship between 300A ~ 15ju micropores and accumulative volume of
micropores was determined using the mercury penetration method.
Surface area of micropore per unit carbon weight, mean micropore size, and
pore volume of brands are shown in Table 6.10. According to the relationship
between accumulative micropore volume and pore diameter, the micropore was
graphically differentiated. Pore size distribution is shown in Figs, from 6.17 to 6.19.
236
-------
The recovery rate of on surface area of micropore per unit carbon weight
was 88 ~ 92%, and mean micropore size was increased 2 ~ 9% after regeneration.
The recovery rate of total volume of micropores (0 ~ 15/u) was 96 to 103%. Volume
of micropores of 300A ~ 15/u was recovered 101 to 118%, and that for 0 ~ 300A
was reduced. In the micropores of 0 ~ 300A, 30 ~ 60A micropore volume was
recovered 102 ~ 114%, while 12 ~ 30A micropore volume and 12A micropore
volume were recovered 80 ~ 90% and 87 ~ 92%, respectively. In order to assess
the size of matter adsorbed to the activated carbon from Table 6.10 and Fig. 6.17 ~
6.19 pore size-wise volumetric adsorption rates are shown in Table 6.11. Adsorbed
matter accounted for 68.4 ~ 82% volumetrically of micropores of not exceeding
30A.
In the regeneration experiment, micropores were reduced both relatively and
absolutely, and transitional pores and macropores were increased. It is said that
iodine number becomes proportional to the surface area of micropores of larger
than 10A, methylene blue number to that of more than 15A, and molasses decolor-
ing index to that of more than 28A. With reference to Fig. 6.13, this is verified as
the recovery rate of molasses decoloring index is higher than that of methylene
blue number and iodine number.
(5) Results of exhaust gas measurement (Reference)
Measurements of dust, SOx, NOx and odorous index, etc. at the outlet of
scrubber of after-heating room are shown in Table 6.11.
The dry gas flow rate at the outlet of scrubber was 373 Nm3/hr which might
include a measuring error. Its design value is near actual flow rate of the effluent
gas from after-heating room. Odorous index of gas at the outlet of scrubber is
seen increased, which might have been due to stripping of organic compounds
contained in wastewater because secondary effluent was used for scrubbing.
Removal of hazardous materials, except NOx was high, justifying the performance
of the equipment.
6.2.8 SUMMARY
(1) Regeneration achievements by characteristics
Apparatus density: —
As a merkmal for the regenerative recovery rate, the apparent density which
can easily be assessed on the spot in a short time was employed, and the recovery
rate became around 100.
Mean particle size: —
Brand A reduced by 3.7%. Other brands increased to the contrary. This might
have been attributable to inorganic matter and deposit carbon. The increment of
ash content was 0.9% for brand A, and 1.2 to 1.9% for brands B and C.
Harness number: —
No remarkable reduction of hardness number of regenerated carbon was
noticed.
Methylene blue number, iodine number, molasses decoloring index, phenol value
237
-------
and ABS value: —
The adsorption rate was highest in ABS value, followed by methylene blue
number, and molasses decolouring index. The recovery rate was lowest in methylene
blue number, followed by ABS value and iodine number. The molasses decoloring
index recorded the highest recovery rate, showing 95 to 103%. Iodine number
is proportional to surface area of micropores of 10A and larger and methylene
blue number is proportional to that of 15A and larger. Generally, the higher the
adsorption rate, the lower the recovery rate.
But the recovery rate of molasses decoloring index which showed a high
adsorption rate is high, and the recovery of transitional pore is easy.
Micropore characteristics: —
From 23 to 35% of the total micropore volume of activated carbon was
occupied with adsorbed matter. Of the total adsorbed matter, 68 to 84% went to
micropores of 30A or smaller. Like as general adsorption characteristics, adsorption
rate of micropore was high, and the recovery rate was low, accordingly. The micro-
pores of regenerated carbon were reduced relatively and absolutely, and transitional
pores were increased relatively and absolutely.
As regards the macropores, there was little difference between fresh and
regenerated carbon.
Yield of regeneration (recovery rate): —
Volumetric recovery rate (A) was 94 to 97%, and gravimetric recovery rate
was more than 94%. As the apparent density was taken as a merkmal, the recovery
rate became high.
(2) Comprehensive Evaluation of the Experiment
As discussed in the foregoing, the capacity recovery rate of spent carbon was
90 to 95%, and the yield was 94 to 97%. The capacity recovery rate is reciprocal to
the yield. It is difficult to judge which we should notice as index capacity recovery
rate or yield in regeneration recycle of carbon. So long as the experiment is
concerned, both showed satisfactory results. The regeneration temperature was very
stable. The oxygen gas concentration in the furnace was as low as less than 0.1% on
an O2 monitor, and burning off of activated carbon was not noticed. The running of
the furnace was possible for an extended period under steady state conditions.
under steady state conditions.
Adsorbed matter from the secondary effluent was represented by such as
adsorbed to micropores of less than 30A. Iodine number, methylene blue number
and ABS value should be taken as merkmal for regeneration; however, if their
recovery rate is set at 100% or more, there is a great possibility of getting the yield
reduced. For this reason, adoption of methylene blue number which is proportional
to comparatively large pores out of macropores and the apparent density which
is proportional to the yield will be practically warrantable for the regeneration
purposes.
238 -
-------
6.3 LABORATORY REGENERATION TEST OF GRANULAR ACTIVATED
CARBON
6.3.1 INTRODUCTION
Along with the pilot plant scale regeneration experiment discussed under 6.2,
a laboratory regeneration test of spent carbon obtained from Kyoto Pilot Plant
has been conducted using a laboratory furnace. The test is still under way, and
submitted here are the results obtained so far.
6.3.2 LABORATORY EQUIPMENT USED
The regenerating furnace used is a part of a multi-hearths type furnace. It is
composed of a combustion chamber and a heating chamber as illustrated in
Fig. 6.20. The heating chamber is equipped with an agitator which permits
ploughing-up of sample. The charging of sample is accomplished from the top
cover, and the with drawing is carried out from the outlett equipped in the hearth
bed while operating the agitator. The performance of the furnace is as follows.
Max. operating temperature in the bottom of heating chamber: 1,100°C
Effective dimensions of heating chamber: 458 mm 0 x 191 mm H
The temperature control of the heating chamber is undertaken by two thermometric
controllers equipped in the chamber and one thermometric controller equpped in
outside of the chamber as well as by combustion burners. Temperatures in the
furnace are recorded automatically.
6.3.3 TESTING METHOD
(1) Sample
In the test, spent carbon of brand A obtained from Kyoto Pilot Plant was used.
The spent carbon was completely saturated with water, and 5 lit. were sampled and
drained for 30 min. In this state the water content was 48 to 51%.
(2) Temperature setting
Atmospheric gas temperature in the top zone of the heating chamber were
set at 500, 600, 700, 800, 900, and 1,000°C.
(3) Atmospheric gas for regeneration test
Character of the atmospheric gas in the regenerating furnace was as follows.
C02 Content 11.6 ~ 15 V/V %
O2 Content 0-1.2
CO Content 0 ~ 2.3
The measurement was carried out with an Orsat gas analyzer. Steam activation
was not carried out.
(4) Items measured
The measured items are as follows.
(i) Apparent density
(ii) Iodine number
(iii) Methylene blue number
All these measurements were in accordance with JIS K 0102.
- 239
-------
6.3.4 RESULTS OF TEST
(1) The apparent density vs. temperature relationship is shown in Fig. 6.21. The
apparent density of regenerated carbon was almost the same level as that of
fresh carbon when an atmospheric gas temperature were from 500 to 800° C
but was smaller when an atmospheric gas temperature was above 900° C.
(2) The iodine number vs. temperature relationship is shown in Fig. 6.22
The spent carbon was rejuvenated at 800°C almost to the level of fresh
carbon. With increase in temperature above 900°C, iodine number increases
toward saturation.
(3) The methylene blue number vs. temperature relation-ship is shown in Fig. 6.23.
The spent carbon is rejunenate to the level of fresh carbon at 900°C.
(4) When viewed from the above three indices, the optimum atmospheric gas
temperature is found to be 800° C if steam activation is not carried out.
240
-------
Table 6.1 Contactor Design
Colum
Brand
Name of carbon
Particle size
Bed depth
No. 1
No. 2
A: CALGON SGL 8/30
FILTRASORB 300
8 x 30
No. 3
. No. 4
B: CALGON CAL 12/40
FILTRASORB 400
12 x 40
No. 5
C: TAKEDA
No. 6
SHIRASAGI
W 8/32
8 x 30
3,000m/m
241
-------
Table 6.2 CODMn Removal by Filtration Effect of Granular Activated Carbon Contactor.
Jun. 13
Jun. 27
Aug. 7
Nov. 28
Mean
Jun. 13
Jun. 27
Aug. 7
Nov. 28
Mean
No. 1
L
116.6
119.3
55.75
163
A
0.609
0.170
0.175
0.376
B
0.746
0.204
0.448
0.330
0.432
No. 2
L
116.6
119.3
62
163
A
0.154
0.144
0.160
0.256
B
0.189
0.172
0.369
0.224
0.239
No. 3
L
120.25
113.8
55.25
168.5
A
0.455
0.130
0.134
0.389
B
0.541
0.163
0.346
0.330
0.345
No. 4
L
120.25
113.8
55.4
168.5
A
0.118
0.104
0.116
0.185
B
0.140
0.131
0.299
0.157
0.241
No. 5
L
110.6
117.8
55.75
170
A
0.579
0.126
0.162
0.463
B
0.748
0.153
0.415
0.389
0.426
No. 6
L
110.6
117.8
63
170
A
0.155
0.123
0.190
0.225
B
0.200
0.149
0.431
0.189
0.302
Note: L = Adsorption Run Length
A = Backwashed COD^n Loading per
B = Backwashed COD^n Loading per
One Time (kg)
Unit Volume of treated Water (mg/m3)
- 242
-------
Table 6.3 Operational Condition of Regenerater
Contactor
Brand of Carbon
Column
Spent Carbon
Total Feed Weight kg WSC
kg DSC
Spent Carbon
kg WSC
kg DSC/Hr
Spent Carbon
Average Moisture wt %
Temperature at each Hearth
Outlet of Exhaust Gas °C
Second Hearth °C
Third Hearth °C
4th Hearth °C
5th Hearth °C
6th Hearth °C
After Heat Room °C
Inlet to Scrubber °C
Outlet of Scrubber °C
Retention Time min
LPG for Fuel Aid
4th Hearth 2/Hr
5th Heartli 2/Hr
6th Hearth £/Hr
Total 2/Hr
Steam Fed
4th Hearth kg/Hr
6th Hearth kg/Hr
Total kg/Hr
Air Supplied m3/Hr (°C)
m3/Hr (°C)
Fuel Consumption 2/Hr
Gas Content CO % (Hearth)
CO2 % (Hearth)
O2 % (Hearth)
No. 1
No. 2
Brand A
Primary
Column
1592.9
960.5
65.5
39.5
39.7
260-300
510-520
540-560
920-930
920-930
920-930
850-870
600-620
70-80
30
1383.6
818.6
959.2
3161.4
9.3
19.8
29.1
(30)
81.35
5.45
3.0(6)
12.2(6)
0.11(1-6)
Secordary
Column
1609.9
931.6
59.3
34.4
42.1
220 -270
410 -420
485 -495
900 -905
900 -90S
900-905
820-860
590-620
50-60
30
1206.0
779.4
846.1
2831.5
11.7
21.3
33.0
(29)
77.68
6.36
3.4(4)
12.0(4)
0.11(1-6)
No. 3
No. 4
Brand B
Primary
Column
1445.4
830.7
58.4
33.6
42.5
250-280
450-455
500~510
910-920
910-920
910-920
850-860
620-640
50
30
1198.6
893.0
772.7
2864.3
10.9
20.0
30.9
(32)
76.45
6.22
2.4(4)
12.1(4)
0.11(1-6)
Secordary
Column
1553.1
852.7
58.4
32.1
45.1
240
390 -400
450-460
880
880
880
830-840
620
50
30
1091.0
753.1
687.6
2531.7
9.9
20.3
30.2
(28)
71.35
7.07
2.8(6)
12.2(6)
0.11(1-6)
No. 5
No. 6
Brand C
Primary
Column
1674.4
961.4
62.0
35.6
42.6
250-265
450-460
495-510
905-915
905-915
905-915
820—840
600-620
50
30
1177.0
842.8
726.1
2745.1
10.4
20.6
31.0
(32)
76.89
6.0
2.0(2)
12.1(2)
0.11(1-6)
Secordary
Column
1657.1
947.5
59.5
34.0
42.8
220 -240
420 —430
510-520
890 -900
890 -900
890 -900
820 —860
580 -630
60-70
30
1182.1
775.5
623.4
2581.0
9.7
19.7
29.4
(30)
71.85
6.88
2.8(6)
12.1(6)
0.11(1-6)
(Note) WSC = Wet Spent Carbon DSC = Dry Spent Carbon
- 243 -
-------
Table 6.4 Volumetric Recovery Rate (A)
Column No.
Bed depth before regeneration
mm
Bed volume before regener-
ation m3
Bed depth after regeneration
mm
Bed volume after regeneration
m3
Volumetric recovery rate
%
No. 1
2,902
2.03
2,777
1.94
95.6
No. 2
2,897
2.03
2,723
1.91
94.1
No. 3
2,744
1.92
2,670
1.87
97.4
No. 4
2,897
2.03
2,732
1.91
94.1
No. 5
3,024
2.12
2,905
2.03
95.8
No. 6
2,895
2.03
2,782
1.95
96.1
- 244
-------
Table 6.5 Gravimetric Recovery Rate
Column No.
Wet weight of spent car-
bon (A) kg
Mean moisture of spent
carbon (B) %
Weight ratio of adsorbed
matter to carbon (C) %
Dry weight of spent
carbon (D) kg
Wet weight of regenerated
carbon kg
Average moisture of regenerated
carbon %
Dry weight of regenerated
carbon kg
Gravimetric recovery rate
%
No. 1
1,592.9
39.7
0.149
836.0
1,370.6
41.3
804.1
96.2
No. 2
1,609.9
42.1
0.114
836.7
1,390.6
43.4
786.5
94.0
No. 3
1,445.4
42.5
0.193
696.7
1,271
43.9
712.7
102.3
No. 4
1,553.1
45.1
0.172
727.5
1,286.1
44.5
713.8
98.1
No. 5
1,674.4
42.6
0.188
809.0
1,422.0
43.0
811.3
100.2
No. 6
1,657.1
42.8
0.134
835.9
1,424.2
43.1
810.9
97.0
D = A • (1 -
100 1 +C
- 245 -
-------
Table 6.6 Volumetric Recovery Rate (B)
Column No.
Dry weight of spent carbon
kg
Apparent density of spent
carbon
Volume of spent carbon
m3
Dry weight of regenerated
carbon kg
Apparent density of regener-
ator carbon
Volume of regenerated carbon
m3
Gravitational recovery rate
%
No. 1
960.5
575
1.67
804.1
485
1.66
99.3
No. 2
931.6
552
1.69
786.5
485
1.62
96.1
No. 3
830.7
565
1.47
712.7
450
1.58
107.7
No. 4
852.7
528
1.61
713.8
450
1.59
98.2
No. 5
961.4
570
1.69
811.3
482
1.68
99.8
No. 6
847.5
555
1.71
810.9
482
1.68
98.5
246 -
-------
Table 6.7 The Result of Heat Treatment in 900°C Nitrogen Gas
•^^
Items
— — ^___^ Brand
•- ~~- —
^^~-\^^ Column
Bed density, backwashed and
drained of spent carbon
Iodine number of spent
carbon
In 900° C
Nitrogen
Gas
After heat
treatment
Recovery rate after
90 min. treatment
Weight ratio of ad-
sorbed matter to
fresh carbon
Recovery rate (%)
Apparent density
Iodine number after heat
treatment
A
No. 1
575
0.68
87.0
0.149
94
512
0.93
No. 2
552
0.73
89.7
0.114
96
500
0.95
B
No. 3
565
0.67
83.8
0.193
92
486
0.96
No. 4
528
0.74
85.3
0.172
96
467
0.99
C
No. 5
570
0.67
84.2
0.188
102
485
0.93
No. 6
555
0.73
88.2
0.134
99
500
0.95
247
-------
Table 6.8 Adsorption Rate to the Capacities
Column
Apparent density %
Methylene blue number %
Iodine number %
Molasses decolorizing index %
Phenol value %
ABS value %
No. 1
19.5
52.9
28.4
55.1
34.2
62.5
No. 2
14.8
29.4
23.2
44.3
-
-
No. 3
25.8
60.0
33.0
57.0
39.5
70.0
No. 4
17.6
35.0
26.0
41.8
3.7
-
No. 5
14.9
55.6
29.5
53.5
39.5
68.1
No. 6
11.9
33.3
23.2
39.8
-
-
- 248 -
-------
Table 6.9 Constants in Freundrich Equation and Recovery Rates
Brand
Fresh carbon
Spent carbon*
Regenerated carbon
Comparison of ad-
sorption capacity at
7 ing/2 TOC level
Comparison of ad-
sorption capacity at
3 mg/2 TOC level
1/n
K
1/n
K
1/n
K
Fresh carbon
Regenerated carbon
Recovery rate
Fresh carbon
Regenerated carbon
Recovery rate
Brand A
1.45
0.006
1.75
0.0005
1.0
0.011
0.094
0.072
76
0.028
0.031
111
Brand B
1.4
0.006
1.75
0.0004
1.1
0.010
0.100
0.084
84
0.029
0.033
114
Brand C
1.4
0.007
1.7
0.0005
1.05
0.010
0.099
0.073
73
0.030
0.030
100
* The spent carbons are from Primary column
249
-------
Table 6.10 Micropore Characteristic of Each Carbons
Surface Area
m2/g
Mean Diameter
of Micropore A
Volume of
Micropore cc/g
0~15;U
Volume of
Micropore
30dA~15;U
Volume of
Micropore
-300&
Volume of
Micropore
30 ~ 60A
Volume of
Micropore
12-30&
Volume of
Micropore
~12A
Brand A
Fresh
Carbon
980
20.5
0.820
0.317
0.503
0.058
0.176
0.205
Spent
Carbon
No. 1
495
22.5
0.535
0.257
0.278
0.039
0.082
0.104
No. 2
610
22.5
0.629
0.285
0.344
0.044
0.111
0.119
Re gen
Car
905
22.4
0.825
0.319
0.506
0.063
0.163
0.185
erated
son
Recov-
ery
Rate
92
-
101
101
101
108
93
90
Brand B
Fresh
Carbon
1065
21.8
0.901
0.321
0.580
0.065
0.218
0.206
Spent
Carbon
No. 3
470
24.0
0.553
0.271
0.282
0.043
0.092
0.080
No. 4
590
22.0
0.610
0.282
0.328
0.043
0.109
0.111
Regen
Cart
935
22.4
0.866
0.343
0.523
0.074
0.177
0.180
srated
>on
Recov-
ery
Rate
88
-
96
107
90
114
81
87
Brand C
Fresh
Carbon
970
20.6
0.787
0.287
0.500
0.054
0.163
0.216
Spent
Carbon
No. 5
500
22.0
0.537
0.263
0.274
0.037
0.088
0.086
No. 6
580
22.1
0.594
0.274
0.320
0.040
0.107
0.126
Regen
Carl
850
22.0
0.808
0.340
0.468
0.055
0.131
0.198
srated
jon
Recov-
ery
Rate
88
-
103
118
89
102
80
92
-------
Table 6.11 Distribution of Absorbed Matter along with Pore Size
Column
Total micropores volume
0 ~ 15jU cc/g
Reduction of micropores
volume % 0 ~ 1 5ju
Reduction of micropores
Volume % 300A~15jU
Reduction of micropores
Volume % ~ 300A
Reduction of micropores
Volume % 60 ~ 300A
Reduction of micropores
volume % 30 ~ 60A
Reduction of micropores
volume % 12 -30 A
Reduction of micropores
volume % ~ 12A
No. 1
0.535
34.8
21.1
78.9
3.8
6.7
33.0
35.4
No. 2
0.629
23.3
16.8
83.2
—
7.3
34.0
45.0
No. 3
0.553
38.6
14.4
85.6
6.9
6.3
36.2
36.2
No. 4
0.610
32.3
13.4
86.6
8.9
7.6
37.5
32.6
No. 5
0.537
32.8
9.6
90.4
1.6
6.8
30.0
52.0
No. 6
0.594
24.5
6.7
93.3
10.4
7.3
29.0
46.6
- 251 -
-------
Table 6.12 Determination of Exhausted Gas from the Furnace
^-^^^ Position
Items ^^^~~^^^
Temperature of gas
Dry gas flow
Moisture
Soot
S02
NO
NOX
Odor PO
C02
02
°C
Nm3/H
Vol%
g/Nm3
ppm
ppm
ppm
-
Vol%
Vol%
Outlet of
furnace
240
69
42.4
1.31
3
62-74
65-76
11.9
10.9
3.3
Outlet of
after heat-
ing room
620
675
22.5
0.16
235 ~ 240
100- 110
105- 115
2-.6
11.4
4.0
Outlet
scrubber
40
373
2.4
0.05
6-9
113- 123
118- 128
5.3
8.3
8.6
Method used for
analysis
TC-Thermometer
JIS Z-8808
JIS Z-8808
JIS Z-8808
.JISK-0103
JISK-0104
Equilibrium method
with salt water
Orsat Analyzing
method
252
-------
Mark
CT
S
MT-1
MT-2
HF
P-l
P.2
P.3
Equipments
Carbon ConUclor
Intermediate PW Holding
Tank
FMT for PW
FMT for BWW
FW Sample Hold ing Tank
Feed Pump
Intetmediate Feed Pump
Pump for BW
Mark
P-4
SP-]
SP-2
V-l
V-2
V-3
V-4
V-5
Equipments
Pump fot SW
Sampling Pumps for FW
Sampling Pumps for PW
Valves for FW
Valves for PW
Valves for BW
Valves for SW
Valves for Headloss flage,
WS
Mark
V-6
P-5
P-6
Sol-]
Sol.2
Lsw.l
Lsw-2
Uw-3
Equipments
Valves for BWW
Pump for BWW Dram
Handing Water Pump
Solenoid Samplers
Solenoid Samplers
WLS for CT
WLS for S
WLS for FW Holding
Tank
Mark
Lsw^
Fi-1
Fi-2
Fu-1
Fu-2
Fi-3
Fu.3
Lsw-S
Equipments
WLS for PW Holding Tank
Fl for BW
FlforSW
FS for BW
FSforSW
FllbrFW
FSforFW
WLS for Drain Pil.
(Abbreviations) FW: Feed Waler, PW: Carbon Product. BW: Backwash Water, SW: Surface-wash Water, BWW: Backwash Waste Water,
FMT; Row Measuring Tank, WLS. Water Level Switch, FI: Flow Indicator, FS. Flow Meter Senser.
Fig. 6.1 Flow Chart of Carbon Contactor
-------
Start
Q
O
CQ
-No. 2 Eff.
Secondary Column
Fig. 6.2 (a) BOD Adsorption by Granular Activated Carbon of Column No. 1 and No. 2
-------
cn
Cn
No. 1 Int.
—•— No. 1 Eff
— A— No. 2 Eff,
-f ' ' ' —i 1 r — —'"i
APR. MAY JUN. JUL. AUG. SEP.
1974
Fig. 6.2 (b) BOD Adsorption by Granular Activated Carbon of Column No. 1 and No. 2
OCT.
NOV.
-------
to
Ln
JAN.
FEB.
Fig. 6.2 (c) BOD Adsorption by Granular Activated Carbon of Column No. 1 and No. 2
-------
en
--J
"SB
c
Q
a
No.l Inf.
No.l Eff
»— No.2 Eff
10
NOV.
1973
Fig. 6.3 (a) COD|\/|n Adsorption by Granular Activated Carbon of Column No. 1 and No. 2
-------
1NJ
tn
cc
Q
O
U
No. I Inf.
No. 1 Eff
— A-- No. 2 Eff
10
APR.
OCT.
NOV.
Fig. 6.3 (b) CODMn Adsorption by Granular Activated Carbon of Column No. 1 and No. 2
-------
en
UD
o.
o
JAN.
FEE
1975
Fig. 6.3 (c) COD|y/|n Adsorption by Granular Activated Carbon of Column No. 1 and No. 2
-------
Start
o
NOV. DEC.
1973
JAN.
FEB. ' MAR.
1974
Fig. 6.4 (a) TOC Adsorption by Granular Activated Carbon of Column No.1 and No. 2
-------
APR.
OCT.
NOV.
Fig. 6.4 (b) TOC Adsorption by Granular Activated Carbon of Column No. 1 and No. 2
-------
No.l Int
No.l f.ff
- + - No.2 Bff
JAN.
FEB.
MAY
JUN.
MAR. APR.
1975
Fig. 6.4 (c) TOC Adsorption by Granular Activated Carbon of Colum No. 1 and No. 2
JUL.
-------
mg/S
K
i n
5-
0
17.9
==?
MAY 8
«
T
C
BOD;
BOD5
Inf. No.l No.2
Eff. Eff.
mg/S
20
10-
No.3 No.4
Eff. Eff.
MAY 8
Inf. No.l No.2
Eff. Eff.
No.3 No.4
Eff. Eff.
10-
MAY 19
No.5 No.6
Eff. Eff.
mg/e
20
10-
Inf. No.l No.2
Eff. Eff.
IIIIHI! 0-N
No.3 No.4
Eff. Eff.
No.5 No.6
Eff. Eff.
N02-N
NH4-N
MAY 19
No.5
Eff.
No.6
Eff.
Inf.
No.l
Eff.
No.2
Eff.
No.3
Eff.
No.4
Eff.
No.5 No.6
Eff. Eff.
Fig. 6.5 Effect of Nitrification in Contactor on Effluent BOD5
- 263 -
-------
Fig. 6.6 Corelation between CODMn and TOC
264
-------
100
Q
P. 50
5000
10000
Quantity of Treated Wastewater
15000
17500m3
Fresh Carbon of No. 1 Column
Fresh Carbon of No. 2 Column
Regenerated Carbon of No. 1 Column
Regenerated Carbon of No. 2 Column
17500
20000
30000
25000
Quantity of Treated Wastewater
Fig. 6.7 Accumulative COD(\/|n Adsorption Curve of Column IMo.1 and No.2
35000m3
265
-------
220
200
Nov. 28, 1974
00
e^
§.
'o
-d
3
GO
1 2 3
10 11 12 (Min)
Backwashing Time
Fig. 6.8 SS Variations of Backwash Wastewater
-------
to
Column
Column
- Column
- Column
- Column
- Column
9 10 11 12 (Min)
Fig. 6.9 CODMn Variations of Backwash Wastewater
-------
Start
INJ
ON
oc
NOV. ' DEC.
1973
JAN.
FEB.
1974
MAR.
Fig. 6.10 (a) ABS Adsorption by Granular Activated Carbon of Column IMo. 1 and No. 2
-------
ON
0.5
0.2
0.1
APR.
MAY.
JUN.
JUL.
AUG.
SEP.
OCT.
NOV.
1974
Fig. 6.10 (b) ABS Adsorption by Granular Activated Carbon of Column No. 1 and No. 2
-------
Re Start
0.
0.\
JAN.
FEB. MAR. APR. MAY ' JUN.
Fig. 6.10 (c) ABS Adsorption by Granular Activated Carbon of Column No. 1 and No. 2
JUL.
-------
APR. 1 mg/e
BODS
20-
20-
10-
10-
Inf. No.l No.2
Eff. Eff.
No.3 No.4
Eff. Eff.
No.5 No.6
Eff. Eff.
20
10-
APR. 1
TOC
0.5
- 0.4
0.3
0.2
0.1
Inf. No.l No.2
Eff. Erf.
No.3 No.4
Eff. Eff.
No.5 No.6
Eff. Eff.
APR. 1
CODMll
No.l No.2
Eff. Eff.
No.3 No.4
Eff. Eff.
No.5 No.6
Eff. Eff.
APR. 1
ABS
Inf. No.l No.2
Eff. Eff.
No.3 No.4
Eff. Eff.
No.5 No.6
Eff. Eff.
Fig. 6.11 Comparison of Adsorption Effect with Change of Items and Brands
- 271 -
-------
Ji
—t
A
A
A
Meter "-
^
^
^
\fatclr
I .
-P
I t
' i
M
I I I
•t
Water
9
L
r
Ml \
>-
Water
-J
ICJMl
Atmosphere
l'-l Fuel Gas
SC-1 Screw Conveyer
RF-1 Regeneration Furnace
OP-1 Oil Pump
A-l Exhaust Gas Furnace
D-l Scrubber
S-l Chimney
B-l Boiler
T-l Quench Tank
T-2 Seal Tank
T-3 Dewatering Tank
F-l Exhasted Gas Fan
CP-1 Recycle Pump
Fig. 6.12 Flow Diagram of the Regeneration System
-------
500-
m2/g
109
50-
Back Washed Bed Density
A: 99%
B: 100%
C: 103%
•A
D
i Fresh Carbon
ii Spent Carbon of Primary Column
iii Spent Carbon of Secondary Column
iv Regenerated Carbon
Methylene Blue Namber
Recovery Rate A: 94%
B: 95%
C:
50-
0
mg/i!
50 -
Molasses Decolorizing Number
Phenol Value
A: 93%
B: 96%
C: 93%
I
iv
100 .
Iodine Number
A: 93%
B: 94%
C: 94%
mg/C
100-
Fig. 6.13 Effect of Regeneration on Some Evaluation Items
- 273 -
-------
Fig. 6
0.1
0.08
0.06
0.04
0.03
0.02
0.01
14 TOC Freundrich Line of Brand A Carbon
//
/
/
^
s.y
%
/
/
'
_Y
/
/•"
1
&
(
/
{
B
/
/
\ 2 3 456789 10
Equilibrium TOC (mg/C)
Fig. 6.15 TOC Freundrich Line of Brand B Carbon
O.I
0.08
0.06
0.04
0.03
0.01
4&
P
1
3 456789 10
Equilibrium TOC (mg/C)
Fig. 6.16 TOC Freundrich Line of Brand C Carbon
3 4 5678910
Equilibrium TOC (mg/C)
20
n c\%
0 06
n n4
oo
^003
n n^
0 01
/
[/
c
^
(
«•/
4('
/
^
^
/
r^
X
&
/
<>
[
^
^j-,
y
c.
4
3
274
-------
0.9
0.8
Fresh Carbon
0.6
Spent Carbon in Secondary Column
o
o
Spent Carbon in Primary Column
0.4
>
0.2
1.0
3.0
4.0
5.0
logD [A]
10
50
102
5-102 103
Diameter of Micropore D [A]
5-103 104
5-104 10s
Fig. 6.17 Pore Size Distribution of Brand A Carbon
-------
^ 0.4 -
Q
DO
0.2 -
Fresh Carbon
Regenerated Carbon
Spent Carbon in Primary Column
Spent Carbon in Secondary Column
1.0
2.0
3.0
4.0
5.0
logD[A]
1 1 \ 1 _l — 1 — L
10
50
102
5-102 103 5-103
Diameter of Micropore D [A]
104
5-10' 10s
Fig. 6.18 Pore Size Distribution of Brand B Carbon
-------
0.9
0.8
t 0.6
Q-
O
>
0.4
0.2
_0
-------
To Chimney
oo
~-J
CO
Fan
/V^^
Steam Inlet
/ Sand Seal
n !j~' / Gas Sampler
In
Jl
-t
Heating Chamber
[T- ^ Arm and Teeth
Combustion Chamber
Main Burner
Blower
Fuel Pump
[Cooling Water]
Fig. 6.20 Flow Diagram of Laboratory Furnace
Fuel Tank
-------
0.6
Spent Carbon
0.5
-a 0-4 -
o
Spent Carbon
0.3 -
0.2
500 600 700 800 900
Regenerating Temperature (°C)
1000
Fig. 6.21 Regenerating Temperature and Apparent Density
-------
(mg/g)
lOOOh
900
800
700
c
3
z
•
o
Fresh Carbon
Spent Carbon
600
500 600 700 800 900
Regenerating Temperature (°C)
Fig. 6.22 Regenerating Temperature and Iodine Number
1000
- 280 -
-------
200
(m£/g)
S
3
J3
CO
o
c
100
Fresh Carbon
Spent Carbon
J_
500
600 700 800 900
Regenerating Temperature (°C)
1000
Fig. 6.23 Regenerating Temperature and Methylene Blue Number
281
-------
CHAPTER 7. AMMONIA REMOVAL BY BREAKPOINT CHLORINATION
PROCESS
7.1 Introduction . 283
7.2 Laboratory Tests 283
7.2.1 Breakpoint Chlorination of Secondary Effluent 283
7.2.2 Effect of pH on Breakpoint Chlorination 284
7.3 Pilot Plant Experiment on Breakpoint Chlorination 285
7.3.1 Outline of the Pilot Plant 285
7.3.2 Results of Operation 285
7.3.3 Troubles over Operation and Performance . . 286
7.4 Future Research 286
- 282 -
-------
7. AMMONIA REMOVAL BY BREAKPOINT CHLORINATION PROCESS
7.1 INTRODUCTION
The breakpoint chlorination process has been practised as a prechlorination
treatment at water treatment, plants receiving water from polluted rivers. The
control of prechlorination process for water treatment is usually made by measuring
residual chlorine. The breakpoint chlorination process for the removal of ammonia
nitrogen in sewage differs slightly from the prechlorination process for water
treatment as follows.
1) Ammonia concentration in sewage varies greatly with time.
2) It is desirable to minimize residual chlorine in chlorinated effluent.
3) The effluent to be discharged into receiving waters must not contain residual
chlorine.
Now, a pilot plant of breakpoint chlorination process is operated at the Toba
Sewage Treatment Plant in Kyoto. This report deals with the results of laboratory
tests to determine factors for the pilot plant installations and an outline of the pilot
plant.
7.2 LABORATORY TESTS
7.2.1 BREAKPOINT CHLORINATION OF SECONDARY EFFLUENT
The experiments were conducted in a batch system using chlorine water and
sodium hypochlorite as the chlorinating agents.
The summary of the results is as follows.
1) Chlorination of the effluent with chlorine water reduces pH, and it is necessary
to use alkali for pH elevation. If sodium hydroxide is taken up for pH control,
its dose rate should be 1.0 to 1.5 times of the chlorine dose rate, in weight
ratio, in order to raise pH up to neutral. Chlorination with sodium
hypochlorite does not require pH control.
2) Breakpoint chlorination is greatly affected by pH. For the purpose of
optimizing the chlorination, pH must be kept in the range of 7 to 8.
3) The reaction is considered to be completed within 5 min. after chlorine
injection. In the event that pH after chlorine dose remains low, the reaction
can be promoted further by raising pH elevated near the neutral.
4) Temperature has little effect on reaction.
5) The breakpoint of the secondary effluent is around the 10:1 Wt. ratio of
C1:NH3-N. C1:N ratios of the breakpoint are essentially the same for both
chlorine water and sodium hypochlorite. Hence, it is necessary to dose about
10 mg/1 of available chlorine as Cl in order to oxidize 1 mg/1 of ammonia
nitrogen in the secondary effluent.
6) Nitrate is formed by Chlorination. With the increase in Cl/N ratio, the amount
of nitrate increases, but remains within 1 mg/1.
7) The color sometimes develops by chlorine dose above the breakpoint depend-
ing upon water quality. This might be ascribable to oxidation of iron or man-
ganese contained in the secondary effluent.
- 283 -
-------
7-2-2 EFFECT OF pH ON BREAKPOINT CHLORINATION
The mechanism of the breakpoint chlorination has not been fully understood.
Nevertheless, it is believed that the most important factor affecting the chlorination
is pH. Samples used in this senes of experiments were distilled water with
ammonium chloride and sodium carbonate. Sodium carbonate was added to the
sample to increase buffer capacity. The experiments were conducted in a batch
system using sodium hypochlorite as a chlorinating agent. Figs. 7.1 and 7.2 show the
results of chlorination with Cl/N ratio adjusted at 8. The initial pH of the buffer
solution of ammonium chloride was controlled in the range of 5 to 10.
From these experiments, the following were disclosed.
1) The development of breakpoint in the sample varies with the initial value of
pH. Judging from the formation of chloramines, it can be classified into three
groups acconding to initial values of pH;(5,6), (7,8,9) and (10).
2) pH in the sample varied before and after chlorination. The two initial pH
groups of (5,6) and (10) showed a rise in pH after chlorination, while the group
(7,8,9) showed a drop.
3) The product in the group (5,6) was mainly dichloramine. The formation of
monochloramine was not significant. The products from the group (7,8,9) were
monochloramine and dichloramine in coexistence in nearly the same
concentration. In the group (10), monochloramine alone was present.
It was found that there was a difference in the location of breakpoint among
the three groups. Figs. 7.3 and 7.4 show the results obtained by chlorination with
Cl/N ratio being changed. The initial pH value of each sample was set at 4.5, 7.5
and 10.2, respectively. The results are summarized below.
1) At pH 10.2, no clear breakpoint was found.
At initial values of 7.5 and 4.5, the breakpoints were around 8 and 9 in terms
of Cl/N wt. ratio, respectively. The removals of NH3-N at the breakpoint were
97% and 93%, respectively.
2) The main product at an initial pH value of 7.5 was monochloramine, but
smaller amount of dichloramine was formed. At an initial pH value of 4.5, the
main product changed from monochloramine to dichloramine as Cl/N ratio
increased. At an initial value of pH 10.2, monochloramine alone was detected.
3) Formation of (NO2 + NO3)-N after chlorination was barely seen at initial pH
of 10.2. At pH 7.5 and 4.5, however, the formation progressed greatly when
chlorine dosage exceeded the breakpoint. The concentrations of (NO2 +
NO3)-N at initial values of pH 7.5 and 4.5 were 0.20 mg/1 and 0.42 mg/1,
respectively at the breakpoint.
4) At initial value of pH 7.5, the pH after chlorination decreased slightly around
the breakpoint. At the breakpoint for initial pH 4.5, a sharp decline of pH was
noticed during chlorination. Fig. 7.5 shows the chlorination of a ammonium
chloride solution without buffer agent. It is evident from the figure that even
if the initial pH is around 7, pH reduces considerably unless buffer action is
- 284
-------
given.
7.3 PILOT PLANT EXPERIMENT ON BREAKPOINT CHLORINATION
7.3.1 OUTLINE OF THE PILOT PLANT
A pilot treatment facility for the breakpoint chlorination process was installed
in the Toba Sewage Treatment Plant, Kyoto, and is now in operation.
Fig. 7.6 shows a flow diagram and control system of the pilot facility. In this
facility, ammonia in the sewage is measured by an automatic ammonia analyzer. As
a chlorine source, sodium hypochlorite solution containing abrut 15% (W/V) of
available chlorine as Cl, which is on market is used. The dose rate of sodium
hypochlorite is calculated by the following formula. Dose rate (ml/min) = NH3-N
(mg/1) x inflow rate of sewage (m3/d.) x Cl/n ratio - (NaOCl concentration (W/V%)
x 1(T2) H (24 (hrs) x 60 (min)). As aninflow to the process, filtered secondary
effluent or effluent from activated carbon contactors is used. The maximum
capacity of the facility is designed at 250 m3 /day.
The facility is currently being run with the constant flow rate regulated by
valve control. At the maximum design flow rate, the detention time of each
chlorination tank is about 5 min. At present, C1/NH3-N ratio is manually set. Two
automatic ammonia analyzers-colorimetric type and electrode type-are installed in
order to investigate their performances as well. Each type has a measuring range of 0
to 20 mg/1. For the control purposes, one of the two analyzers is employed. The
automated colorimetric analyzer is divided into two portions; filtering and
colorimetering. The filtering portion provides disinfection by heat and filtration of
the sample. This analyzing instrument takes roughly 45 min. from sampling to
measurement. On the other hand, the electrode type instrument requires about 20
min. for measurement. The dosing pump for sodium hypochlorite controls flow rate
by adjusting the stroke and revolutions, and is able to control the dose rate in the
range of 30 to 600 ml/min.
A test for treating the breakpoint chlorination effluent by a carbon contactor
just started from September of this year.
7.3.2 RESULTS OF OPERATION
Table 7.1 and 7.2 show some of the results of the operation of the pilot plant.
Table 7.1 shows the operating conditions and ammonia nitrogen concentration over
a period from May 16 to 22. From this table, the followings are found.
1) The average NH3-N concentrations of the influent and the effluent Were 8.42
mg/1 and 1.10 mg/1, respectively. Therefore, the average removal of ammonia
nitrogen was 86.9%.
2) The concentration of available chlorine in NaOCl solution decreases a little
with time.
Table 7.2 shows the results of water quality analysis on May 21 and 22. From
table 7.2, the followings are found.
1) The NH3 -N removal was nearly 100%. Considering the fact that the residual
chlorine concentration was low, the state was close to the breakpoint.
- 285 -
-------
2) The formations of NO3-N were 0.56 mg/1 and 1.62 mg/1, which were little
higher than in the laboratory tests.
3) The removal of CODMn was about 12.5%.
4) Chloride concentration in the effluent was increased by about 100 mg/1.
7-3-3 TROUBLES OVER THE OPERATION AND PERFORMANCE
The following problems have been brought to the fore since the start-up of the
pilot plant.
1) When the ambient temperature rises, sodium hypochlorite decomposes,
reducing available chlorine. The decomposition becomes significant when the
temperature exceeds 25°C. It was necessary, therefore, to install a dial on the
controller to correct the change in NaOCl concentration. The concentration is
checked periodically and the dial is adjusted manually.
2) NH3-N concentration detected by the colorimetric type automatic ammonia
analyzer is a little lower than by the manual Nessler's method. This problem is
being examined.
3) It has been found that ammonia electrode has a short life. The necessary
frequency of calibration is under study.
7-4. FUTURE RESEARCH
As far as the removal of ammonia nitrogen is converned, the breakpoint
chlorination is very effective. However, addition of chlorine into liquids like
sewage which contains a large amount of organic matter may cause serions
problems. The following are left for the future study.
1) Material balance in the reaction between chlorine and ammonia.
2) Removal of chloramines and chlorinated organic compounds by activated
carbon adsorption through laboratory and pilot scale studies.
286 -
-------
Table 7.1 Results of operators performed 5/16/75 - 5/22/75
Influent of Carbon Contactor
tsj
CO
5/16
5/17
5/18
5/19
5/20
5/21
5/22
16 : 00
">0 : 00
23 : 00
4 : 00
8 : 00
11 : 00
16 : 00
20 : 00
24 : 00
3 : 00
8 : 00
12 : 00
16 : 00
20 : 00
24 : 00
4 : 00
8 : 00
16 : 00
20 : 00
24 : 00
4 : 00
8 : 00
12 : 00
16 : 00
20 : 00
24 : 00
4 : 00
7 : 00
11 : 00
16 : 00
20 : 00
Flow
rate
m3/day
260
251
255
251
248
CI/N
Wt.
ratio
10
10
10
10
10
NaOCl
Concen-
tration
W/V
Of
14.08
14.08
13.86
13.86
13.86
Injection Pump
Stroke
(%)
-
measure
65
-
59
-
VS
Motor
(rpm)
-
nent 8 : 30
350
370
~
Dose
Rate
Calc.
(ml/min)
-
104
96
-
Dose
Rate
Obs.
(ml/min)
-
100
90
-
Obs./Calc.
-
0.96
0.94
-
Colorimelric
Analyzer
Influent
NH3-N
(mg/1)
9.70
10.10
9.75
8.45
8.05
8.50
9.60
8.60
7.25
6.70
6.10
6.15
7.90
10.20
10.90
10.25
9.05
6.20
7.00
7.15
7.10
7.00
7.35
8.40
9.25
9.30
9.00
8.60
8.35
9.10
9.95
Effluent
NH3-N
(mg/1)
0
0
0
0
0
0
1.35
LOO
0.70
0.80
1.60
2.35
1.20
6.55
4.00
0
3.10
0
0
0
0
2.00
0
0.55
0
0
0
0
0
6.20
2.85
Note
Calibration 24 : 00
-------
Table 7.2 Results of Tests
Influent of Carbon Contactor
CO
co
5/21 9 : 00
C1/N = 10
NaOCl Cone.
13.86%(W/V)
5/22 9 : 30
Cl/N = 10
NaOCl Cone.
13.86%(W/V)
Influent
Effluent
Removal
Influent
Effluent
Removal
PH
6.94
7.24
-
7.01
6.91
-
CODMn
(mg/1)
11.5
10.1
12.1
12.6
11.0
12.7
K-N
(mg/1)
7.46
0.43
94.2
10.57
1.01
90.4
NH3-N (mg/1)
Auto-
matic
7.10
0
100
8.40
0
100
Manual
6.15
0.03
99.5
7.25
0.01
99.9
NO3-N
(mg/1)
8.00
8.56
-
8.03
9.65
-
cr
(mg/l)
56.20
166.67
-
58.14
156.98
-
Cl
Residual
(mg/1)
-
1.60
-
-
2.14
-
-------
Cl Residual
(mg/8)
(N02+N03)-
N (mg/2)
3
yo
VI
OJ
10
Fig. 7.1 Effect of pH on Chlorination
Cl/N = 8 (wt. ratio), Total alkalinity = 31.5 mg/2
289
-------
O
X pH after chlo-
rination X
10
Fig. 7.2 Chloramine Formation
290
-------
Total Alkalinity = 86.7 mg/6
10-
-50
ex
Z
Q
Z
6-1
4-
Z 2-
3
•O
oi
o
Total Alkalinity = 45.0 mg/fi
10-
6-
4-
Total Alkalinity = 1 me/C
10 -
O 3
-f
ra
O ,,
Z 6
^ 4 -
O NHj-Nfma/a)
C — Cl Residual.,
(ms/C)
— • — (N02+NO%)-N
(ma/C)
X-pH
-50
-40
-30
•20
•10
0
-50
•40
-30
-20
-10
0
6780
C1/NH3-N (wt. ratio)
Fig. 7.3 Breakpoint Chlorination and pH
- 291 -
-------
20_
is
o
(N
u
X
G
u
15-
10-
5-
pH=4.5
PH=7.5
NH2C1-C1
-0-
-o-
NHC12-C1
-0-
-o-
056 78 9
Cl/NH3-N(wt. ratio)
Fig. 7.4 Chloramine Formation
292 -
-------
10-
"5.
O 6-
i 4
0 "—
NH3-N
Cl Residual (mg/£)
(N02+N03)-N(mg/e)
pH
6789
C1/NH3-N (wt. ratio)
11
- 50
-40
\- 20
h 10
Fig. 7.5 Breakpoint Chlorination and pH
Total Alkalinity - 5.5 mg/£
- 293 -
-------
Head Tank
\
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Influent (fro
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NH3-N Concentration
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-------
CHAPTER 8. PHOSPHATE REMOVAL IN AN ACTIVATED SLUDGE
FACILITY BY ALUM ADDITION
8.1 Outline of Nishiyama Sewage Treatment Plant 296
8.2 Installed Equipment and Devices 297
8.3 Chemical Addition Control 297
8.4 Outline of Methodology 298
8.5 Results and Discussion 298
8.6 Summary 302
8.7 Future Research Project 303
295 -
-------
8. PHOSPHATE REMOVAL IN AIM ACTIVATED SLUDGE FACILITY BY
ALUM ADDITION
Putting newly planned sewage treatment plants aside, the existing sewage treat-
ment plants are said to permit of almost no expansion for functional improvement
including phosphorus removal because of difficulties involved in the acquisition of
rights-of-way. To ward off this problem a method of dosing coagulants like metal
salts, into existing facilities such as aeration tank has been brought into limelight.
This is because the expansion work can be limited to a minor extent - to the installa-
tion of chemical storage tank, dosing pump and additional sludge treatment facility
to overcome excess waste sludge to be developed as a result of chemical dosage.
This method has been evaluated in various ways by E.P.A. of U.S.A. and some
countries in Europe, and has been put to practice. In Japan, the raw sewage is usu-
ally weak in strength, and the data concerning the treatment of this kind of sewage
in this method have been called for.
For example, the domestic sewage in Japan is characterized by BOD of 100 to
180 mg/1. and T-P of 4 to 6 mg/1.
The Public Works Research Institute of the Ministry of Construction and
Nagoya Municipal Government formed a joint project for a demonstration survey at
Nishiyama Sewage Treatment Plant, which is taking in domestic sewage typical of
Japan, of the effects of coagulant on upgrading of the existing plants.
The results of survey will be used not only for Nagoya Municipal Government
but also for those cities that are suffering from similar problems in the upgrading of
existing sewage treatment facilities. The purposes and objective of the survey to be
undertaken by this project are summarized below.
i) Study for a method of reducting the residual phosphorus concentration in ef-
fluent below 0.5 mg T-P/lit.
ii) Study on the impact on the entire functions of plant including increased sludge
production.
iii) Study on the effects of metal salts on biological treatment.
iv) Study for a method of promoting removal of phosphorus and nitrification
simultaneously.
v) Study for a method of removing suspended solids in effluent by rapid sand
filtration, polymer addition, etc.
vi) Study for a recovery method of dosed metal salts.
vii) Development of instrumentation and automatic control techniques
viii) Economic assessment
The demonstration project was started in 1974. Now, alum addition into an
aeration tank is in the progress. The following is an interim report of the survey for
the period from 1974 to July 1975.
8.1 OUTLINE OF NISHIYAMA SEWAGE TREATMENT PLANT
296
-------
Nishiyama Sewage Treatment Plant is a comparatively small sewage treatment
plant for domestic sewage only. The sewage collection is of the separate sewer type,
and the conventional plug flow activated sludge system is adopted for biological
treatment.
Table 8.1 shows an outline of the design and Table 8.2 an outline of the facili-
ties.
This small-scale domestic sewage treatment plant is always facing vilolent fluc-
tuation in both quality and quantity of influent, and thus has been greatly in need
of chemical dose control.
Fig. 8.1 shows diagonal variation of T-P and Sol T-P in the influent.
As shown in Table 8.2, this plant is separated into two bays, and a modification
was made to use one bay as a control and the other as a chemical addition train for
the purpose of comparing them while running under the same operating conditions.
The modification includes separation of return sludge influent channel and
separation of channel leading from the aeration tank to final sedimentation basin.
The sludge had been returned from a hopper of the final sedimentation basin via a
pump well, and a submerged pump was installed at one bay to permit direct sludge
return and withdrawal of excess waste sludge. In this way, the basins were complete-
ly separated from each other. But later, seepage, though little, was found between
the two.
The flow diagram of the facilities is shown in Fig. 8.2.
8.2 INSTALLED EQUIPMENT AND DEVICES
Installed for the purpose of chemical addition were chemical storage tank
(15 m3), chemical pump, and chemical control equipment.
The pump used was a plunger type one capable of changing both speed and
stroke.
Its injection control range was 1 : 30 or 5 to 135 lit./min.
8.3 CHEMICAL ADDITION CONTROL
The chemicals were planned to be dosed to be proportional to phosphorus
loadings., measuring phosphrus, by automatic colorimetric analyzer.
At present, however, we are in the process of developing an equipment for
automatically measuring the phosphorus concentration in the supernatant of mixed
liquor and proportional dosing has not yet been achieved.
For this reason, the delivery rate of the dosing pump was controlled to follow
the signal representing the change in influent flow.
The dosing rate was predetermined. Namely, the alum has been dosed to make
a constant mole ratio of A/P with respect to daily average phosphorus concentration
of the influent.
In this system, if the change in the influent flow takes place in the same way as
the change in quality, proportional control of chemical dose can be achieved. As
illustrated in Fig. 8.2, the qualitative and quantitative changes do not always take
place in the same way. At present, the dosing rate is determined with the daily
average phosphorus concentration taken as 4 mg T-P/lit.
297
-------
The dosing pump motor frequently failed for some time after start-up of the
project.
It was then found that a sharp decline in the influent flow into the aeration
tank due to withdrawal of sludge from the primary sedimentation basin outpaced
the dosing pump. To overcome this problem, the motor speed was reduced when the
influent flow decreased sharply. Now the dosing pump is well in service.
8.4 OUTLINE OF METHODOLOGY
Coagulant and its addition
The coagulant used was liquid aluminum sulfate (alum). Its chemical formula
is Ah (SO4 )3 • 18H2 O, and Ah O3 accounts for some 8%.
Dosing rate was set at 2 in terms of mole ratio of Al/P to T-P in influent or
8 mg/lit. in Al. The dosing position of alum was at the end of the aeration tank.
Later it was found that around this position T-P in the supernatant of mixed
liquor is in many cases about 60% of that in the influent, and the dosing rate now is
reduced half,
Sampling procedure
Samples were taken by an automatic sampler at an interval of 2 hrs to make up
a 24-hr composite sample. The analysis was made 3 to 4 days a week.
Measuremet of sludge
For both bays, the waste sludge was measured with an electromagnetic flow-
meter and an ultrasonic solid meter automatically.
8.5 RESULTS AND DISCUSSION
Addition of alum into the end of the aeration tank started in early February,
1975. The dosing rate remained the same until July, but the period was divided into
two: Phase I from the start to March 30 when water temperature was low and Phase
II from mid-April to the end of July when water temperature rose above 11°C.
Table 8.3 shows the characteristics of the qualities of influent and effluent.
Table 8.4 shows the summary of operating conditions.
In Phase II, the influent flow was a little larger than in Phase I; so was MLSS.
Phosphorus removal
Removal of phosphorus was drastically improved by the addition of alum. As
seen in the table, both Phase I and Phase II saw a reduction of residual phosphorus
concentration in effluent to 0.4 mgP/lit. in T-P and 0.3 mgP/lit. in Orth-P.
In both phases, the phosphorus concentration in the influent was around 3.5
mg/lit., and the removal efficiency was kept of about 90%.
Up until now, the operation has been continued for about six consecutive
months with a Al/P mole ratio set at 2. During this entire period, T-P in the effluent
has always been kept below 0.5 mg/lit., proving that so far as this dosing rate is used,
the target residual phosphorus concentration of less than 0.5 mgP/lit. can be at-
tained.
In the demonstration paint, the control bay also showed a comparatively high
phosphorus removal of 45 to 55% or less than 2 mgP/lit. in terms of residual phos-
298
-------
phorus concentration.
Now investigations are under way as to whether this is due to biological uptake
or coagulation by cations like Ca++ entrained with influent.
In Phase I, the phosphorus content in the activated sludge in the control bay
was 1.7 to 1.9%.
Nitrogen removal and nitrofication
In Phase I when water temperature was low, neither dosed bay nor control bay
had nitrification. But in Phase II, the control bay alone experienced substantial nitri-
fication as water temperature rose up. In early July, the nitrification percentage
based on TKN reduction reached no less than about 60%. The transition is shown in
Fig. 8.3. Alum addition bay did not have nitrified effluent at all for all that it was
operated under the same conditions except for dosing. This may be due to depletion
of alkalinity or interference by aluminum.
In the dosed bay, washout of suspended solids took place extremely in Phase II,
and SRT was as low as about 2 days. This may also be attributable to the prevention
of nitrification. As shown in Table 8.3, the influent alkalinity (85 mg/lit.) was con-
sumed 45 mg/lit. as CaCOs in the dosed bay by the addition of alum, manifesting
the depletion of alkalinity necessary for nitrification.
In the chemical bay, aluminum of some 8 mg/lit. was dosed. The accumulation
in the sludge reached about 12% in Phase II. Now laboratory test is under way as to
how this concentration of aluminum can interfere with the nitrification.
As shown in Table 8.4, the settler has a large overlfow rate, and solids are liable
to be washed out. Accordingly, MLSS in tank cannot be maintained high enough
whereby SRT cannot be maintained. To cope with this problem, a method of reduc-
ing the overflow rate is now under way.
In winter this year, experiments will be made with consideration given to the
addition of alkalinity, intereference of Ar + + , and increase of SRT in hopes of pro-
viding something of a basis for the promotion of nitrification in the process.
Removal of organic matter
Removal of both BODs and TOC was increased by the addition of alum. Com-
pared with the control bay, the dosed bay showed an increase of some 5% in removal
of BOD and some 10% in removal of TOC.
In Phase II, the removal slightly went down in the dosed bay, which might be
attributable to washout of solids.
Soluble BOD in the effluent was 3.6 mg/lit. and soluble TOC 17 mg/lit., or
55% and 82% to total, respectively.
Solid removal
Phase I and Phase II showed a sharp contrast in the removal of suspended solids.
In Phase I, the residual solids in the effluent was smaller in the dosed bay than
the control bay, whereas in Phase II, the control bay showed a smaller value than
the dosed bay.
This might have been due to the following causes.
1) Washout of floe produced by aluminum dose after being transformed into
299
-------
particulates.
In Phase 1, data covered comparatively earlier stage of dose though taken after
a cell residence time, and washout of fine floe was not noticed.
Aluminum content in the solids in the dosed bay was 7% in Phase I and more
than 10% in Phase II.
2) In Phase II, the overflow rate in the control bay was half as much as that in the
dosed bay.
Washout was observed in the morning when influent flow was large.
As shown in Table 8.3, the turbidity also showed the same tendency as SS.
From Oct. this year, a rapid sand filter plant will start operation in order to
launch into a project for solid removal from the effluent.
pH reduction and alkalinity consumption
pH reduction was not so serious as expected. pH reduction due to addition of
alum is about 1 unit, and pH at the end of aeration tank immediately after dose was
about 6.1.
Alkalinity is consumed by chemical dose. Addition of 1 mg/lit. of Af++ resulted
in consumption of alkalinity by 5.5 mg/lit. max. as CaCOs. In the dosed bay, the
consumption was 40 to 45 mg/lit. which corresponded to 8 mg/lit. of added Al+++
considering the portion used for coagulation of phosphorus. In Phase II, dosed bay
saw an alkalinity consumption of some 30 mg/lit. which may have been due to nitri-
fication.
Alkalinity of influent running into Nishiyama Sewage Treatment Plant is 80 to
120 mg/lit. For perfect nitrification or in the vent of dosing when the phosphorus
concentration is high, addition of alkalinity will be almost indispensible.
This may be a matter common to all the sewage treatment plant in Japan which
are processing domestic sewage.
Effects on biological activity and microfauna
The survey of the effects of high-concentration aluminum dose to aeration tank
on microfauna in the activated sludge was one of the greatest interests attached to
the project. Some reports of similar surveys claim that such dose have little effect on
the microfauna. In the project, no particular effects were found so long as the efflu-
ent quality was concerned, though VSS decreased from 70% to 60%.
Table 8.5 shows the results of microscopic observation of population number
of microfauna in the activated sludge in both bays in Phase II.
The differences between the two bays were as follows.
1) Alum dose decreases the number of organisms in the activated sludge on the
whole.
2) Number of species of microfauna in the activated sludge is decreased. Fig. 8.4
shows time-dependent change of the number of individuals of ciliata per unit
MLVSS.
In Phase II, the effluent of dosed bay became milk, white sometimes after rain-
fall. At first, it was considered attributable to the promotion of washout of fine floe
300
-------
of aluminum hydroxide. Later, it was found by a microscopic observation to be
swarms of bacteria analogous to spirochaeta plicatilis.
The bacteria oftentimes were found even in fine weather, though they were
little in number.
The reason why they grow so far as to turn the effluent milk white is still un-
known. Whether the bacteria is spirochaeta plicatilis or not is under study.
Sludge production
The sludge production rate is compared in Table 8.6 between the two bays over
the 11-day period during which aluminum concentration in the mixed liquor was
considered stable.
As touched upon in the foregoing, a little seepage was noticed between the
mixed liquors of both bays.
In Table 8.6, the seepage is compensated for with aluminum addition in the
control bay as a basis. As shown in Table 8.6, the sludge production in the alum-
dosed bay increased as compared with the control bay. The daily average sludge pro-
duction rate over the 11 day period was 613 kg/d. (45.4 mg/lit.) in the control bay
as against 856 kg/d. (72.5 mg/lit.) in the alum dosed bay. Namely, alum dose created
an increase of some 30%. During this period, BODs removal was 590 kg/d. (56
mg/lit.) in the control bay as against 640 kg/d. (61 mg/lit.) in the alum dosed bay,
with a difference of 50 kg/d. (5 mg/lit.) between the two. It is evident that produc-
tion of aluminum phosphate and aluminum hydroxide due to alum addition has a
direct influence over the increase of sludge production.
Assuming that precipitation reaction of alum follows the following formula,
and that 3 mg/lit. of phosphorus in the influent is precipitated with Ar++, the pro-
duction of sludge due to alum addition will be 184 kg/d. (15.6 mg/lit.) in the form
of aluminum hydroxide and 139 kg/d. (11.8 mg/lit.) in the form of aluminum phos-
phate.
A12(SO4)3 +6HCO3 ^2A1(OH)3 +3SO4-2 + 6CCh
A12(SO4)3 + 2PO4-3 -» 2A1PO4 + 3SO4-2
Namely, Aluminum in the sludge in this case will amount to about 110 kg/d or
some 12% of the total sludge volume of 856 kg/d. This estimate showed relatively
high agreement with the observed value.
It was very interesting to notice during the period that the increment in the
alum dosed system washed out along with the effluent.
As regards the sludge production, data collection will be made from a long-term
standpoint.
Dewaterability of the chemical sludge
Dewaterability of alum-treated sludge was examined. For the time being, a
filter leaf test modeling after vacuum filtration is under way.
Interim results may be summarized as follows.
1) For the dewatering of waste sludge developed by alum addition, dose of cal-
cium hydroxide and ferric chloride in combination as conditioner is effective.
2) For sludge with solid content of 2.5% and aluminum content of 10%, filtration
301
-------
velocity can be 10 kg/nr /hr when calcium hydroxide is dosed 50% and FeCb
5%. The moisture content of cake in this case is about 85%.
3) There is little difference in dewaterability of waste activated sludge between
control bay and dosed bay.
4) Dewaterability can be improved sharply by adjusting the ratio of chemical
sludge to primary sludge.
The above refers to the dewatering of raw sludge. In Japan, the dewatering is
practised mostly after anaerobic digestion, and study will be made on the dewater-
ability of sludge containing metal salts after anaerobic digestion.
Cost of chemicals
If the sewage is to be treated with Al/P mole ratio of 2, its treatment cost is
estimated at ¥1.78/m3 (2.32 ^/1,000 gal.) based on the cost of liquid alum pur-
chased by the Nagoya City.
The sewage considered here contains an average phosphorus concentration of
3.5 mg/lit., and the residual phosphorus concentration in the effluent is less than
0.4 mg/lit. If the phosphorus concentration removed is 3 mg/lit., the chemical cost
per removal concentration is estimated to be ¥0.59/m3/mgP/lit. removed (0.774
-------
the addition of alkalinity and effect of aluminum;
4) the microfauna in the dosed bay became different from that in the control bay,
showing extermination or decrease of population and species;
5) the sludge production increased some 30% to 40% from that in the control bay,
increment being attributable to the addition of aluminum;
6) organic matter in MLSS was reduced in alum dosed system to 60% as against
70% of the control system.
7) keeping MLSS at a high level was difficult, mainly because of high overflow rate
observed in the final sedimentation tank, and as a result, SS in the effluent was
increased compared with the control;
8) no trouble was developed in the treatment by the low MLSS, suggesting that
running at a low MLSS may be practicable where the influent is weak as with
the sewage in Japan;
9) the alum dosing cost was ¥l.78/m3 (2.32 c/1,000 gal.). An experiment with a
decreased dosing rate is under way, and precise cost analysis will be made soon.
8.7 FUTURE RESEARCH PROJECT
1) Determination of minimum alum dosing rate necessary to keep the residual
phosphorus concentration in the effluent below 0.5 mgP/lit.
2) Study on the promotion of nitrification when alum dosing is practised.
3) Clarification of sludge production balance.
4) Establishment of proportional chemical dosing control system.
5) Feasibility study on the recovery of slum.
6) Study for a method of removing solids in the effluent
At present, a rapid sand filter pilot plant having an effective surface area of
1 m2 is under construction at Nishiyama Sewage Treatment Plant. Its operation is
scheduled for early Oct. this year.
This filter is divided into 8 basins, and when on basin is being subjected to
backwashing, the effluent of the other basins is used as backwash water.
This is accomplished automatically according to the total head loss increased.
The transfer of backwash water is undertaken by siphon effect, dispensing with
valves otherwise required.
This automatic backwashing, valveless rapid sand filter will be used at once for
the testing of solid removal from the secondary effluent and for the collection of
basic design data necessary for engineering the application of this kind of filter to
the solid removal from the secondary effluent.
7) Examination of merits and demerits of dosing coagulants into primary sedi-
mentation basin.
8) Dosing of iron salts and the like other than alum.
9) Economic appraisal
- 303 -
-------
Table 8-1 Outline of Nishiyama STP
Area served
748 (ha)
1,850 (acre)
Population
served
46,000
Volume of sewage flow
Daily average
20,000 (m3/d)
5.7 (mgd)
Daily maximum
30,000 (m3/d)
7.9 (mgd)
Collection
System
Separate
Sewer
304
-------
Table 8-2 Outline of Nishiyama Facilities
^•v. 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
5.0 x 40x50x2 bay
, n 1st 22.5 0 n
5'0x 2nd 27.5 X3'°
Number
2
1
4
2
3
Total
volume
(m3)
-
245
1,680
4,000
2,250
Design
detention
time
1.2min.
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.
- 305 -
-------
Table 8-3 Summary of Influent and Effluent Quality (Phase I)
Feb. 25 ~Mar. 26, 1975
^^\^^ Item
Category ^^^^
Temp (°C)
pH
Transparancy
Turbidity
SS (mg/C)
Total Alkanility
BOD5 (mg/C)
COD (mg/C)
TOC (mg/C)
T-P (mg/C)
Orth-P (mg/C)
TKN (mg/C)
NH3-N (mg/C)
NO2+NO3-N(mg/C)
Raw sewage
Average
-
-
-
130
135
94
100
69
78
3.44
2.95
22.8
12.2
0.4
Range
11.6~13.6
6.95-7.50
2.0-4.5
67—223
60~232
79~118
96 — 104
54 — 110
77—80
2.80 — 4.40
1.5-6.56
22.5 —23.0
11.3 -13.1
0.1—0.3
Primary effluent
Average
-
-
-
83
52
92
67
48
69
3.44
2.25
23.7
13.9
0.2
Range
11.8—13.6
6.76—7.60
3.0-8.0
51 —111
34—77
69-112
51 —83
42—61
67-72
29.3-4.0
1.71-3.33
22.4 — 25.0
13.2-14.6
0.1 —0.3
Secondary effluent
(Control)
Average
-
-
-
14
12
87
8
14
40
1.95
1.42
18.8
14.1
0.3
Range
11.7—13.6
6.94 — 7.70
15.2~30<
26—65
2-36
70-103
9-16
12 — 17
38-42
1.3-2.7
0.91-1.67
18.6-19.0
14.0 — 14.2
0.28—0.32
Secondary effluent
(Alum, addition)
Average
-
-
-
7
6
52
5.3
10
17
0.27
0.13
17.4
14.4
0.3
Range
11.7 —13.6
6.35-7.30
2.4- 3.0 <
1 -25
2-H
43-65
5.0-5.5
9 — 11
11 —24
0.2-0.4
0.08—0.28
16.9 —17.8
14.0 — 14.7
0.15 —0.34
Removal efficiency
over secondary
Control
-
-
-
83.1
76.9
21.7
88.0
70.8
42.0
43.3
36.7
20.7
-
-
Alum. add.
-
-
-
91.6
88.5
43.6
92.1
79.1
75.3
92.2
94.2
26.5
-
-
-------
Table 8-3 Summary of Influent and Effluent Quality (Phase II)
April 12—June 30, 1975
^^^^ Item
Category ^^^^
Temp (°C)
pH
Transparency (cm)
Turbidity (mg/2)
SS (mg/2)
Total Alkalinity
(mg/fi, CaC03)
BODS (mg/2)
COD (mg/£)
TOC (mg/£)
T-P (mg/£)
Orth-P (mg/S)
TKN (mg/C)
NH3-N (mg/S.)
NO2+NO3-N(mg/£)
Raw Sewage
Average
-
-
-
80.3
118
80.5
98.7
56.1
80.1
3.54
2.16
25.2
14.3
0.11
Range
16.0—21.8
6.8—7.2
2.5-5.5
56.5-132
81-162
59 — 126
68.8 — 124
36.4—76.4
51.8-122
2.59—4.92
0.81 -3.20
21.8-29.1
12.1 — 16.8
0.0 — 0.28
Primary effluent
Average
-
-
-
52.02
41
85.3
64
41.4
58.8
3.45
2.24
25.8
15.7
0.04
Range
16.0 — 21.8
6.8-7.2
3.0-7.0
32.5-92
31-78
62-135
47—95
32.3-55.7
38.4—87.0
2.01-7.90
0.79—4.40
20.6 — 39.1
12.2—25.5
0-0.10
Secondary effluent
(Control)
Average
-
-
-
6.7
6
55
9.5
11.3
19.3
1.49
1.25
13.2
9.7
3.17
Range
16.4 — 21.8
6.6-7.2
1.7—30
4.1 — 11.3
2 — 11
30-95
6.5 —16.5
8.3-14.5
8.1 -36.0
0.67—3.21
0.59-1.97
9.9-21.0
6.6 — 17.4
0.20-6.7
Secondary effluent
(Alum, addition)
Average
-
-
-
15.7
21
39
6.4
12.5
14.9
0.39
0.31
17.8
14.1
0.35
Range
16.4-21.8
6.4-7.3
6.5—30
3.5-62
2.0 — 66
13.5—53.5
4.7—8.3
7.0-37.5
7.1-22.3
0.14 — 0.69
0.06—0.75
16.0-21.6
12.3-16.4
-0.07 -0.83
Removal efficiency
over secondary
Control
-
-
-
87.1
84.5
-
_ 85.1
72.7
67.1
56.8
44.2
49.1
38.3
-
Alum. add.
-
-
-
69.9
49.7
-
90.0
69.8
74.6
88.7
86.2
31.3
10.3
-
-------
Table 8-4 Summary of Plant Operation
^^ Item
Category \^
o
C^)
C3
0^
o>
CO
n3
OH
Control
Alum, addition
Control
Alum, addition
Average
daily flow
(m3/d)
10,650
10,650
11,800
11,800
Aerator
Aeration
time
(h)
4.5
4.5
4.1
4.1
Return
sludge rate
(%)
30
30
30
30
Air flow
rate
(times)
4
4
4
4
MLSS
(mg/£)
640
950
1,030
930
MLVSS
(mg/2)
460
645
717
560
SVI
117
115
105
111
Organic
load
(kg BOD/kg SS)
0.55
0.37
0.36
0.40
Final settler
Detention
time
(hr)
1.7
1.7
3.1
1.5
Overflow
rate
(m3/d/m3)
42.6
42.6
24
47.2
OJ
o
CO
-------
Table 8-5 Microfauna in Activated Sludge (Alum. Addition)
(N/ml)
s^k^^e^a
Euglena
Unknown
flagellata
Tetrahymena
Litonotus
Unknown ciliata
Aspidisca
Vorticella
Opercularia
Carchesium
Zoothamnium
Epistylis
Rhabdostyla
Tokophrya
Rotaria
Nematoda
May 20
-
60
40
-
-
-
60
-
-
-
80
20
-
-
May 22
-
180
20
-
-
20
20
-
40
-
80
40
-
20
May 23
200
40
20
-
-
80
100
-
-
-
120
140
20
20
May 28
-
-
-
-
-
-
100
-
-
-
140
-
-
20
June 2
-
-
-
-
-
20
240
-
80
-
40
-
-
40
June 4
-
-
20
-
-
20
720
-
80
-
160
100
60
-
20
June 5
-
-
-
-
-
40
200
-
-
-
20
-
40
-
June 9
-
-
-
-
-
-
40
-
-
-
-
80
20
-
June 12
-
-
-
-
-
-
200
-
-
-
140
140
40
-
July 2
-
-
-
-
-
40
120
-
-
-
200
220
-
20
o
(£3
-------
Table 8-5 Microfauna in Activated Sludge (Control)
(N/ml)
Euglena
Unknown
Flagellata
Tetrahymena
Litonotus
Unknown ciliata
Aspidisca
Votticella
Opercularia
Carchesium
Zoothamium
Epistylis
Rhabdostyla
Tohophrya
Rotaria
Nematoda
May 20
40
-
260
60
620
-
-
-
-
640
-
20
-
May 22
-
80
320
-
340
80
-
-
220
80
100
20
20
May 23
420
730
2,000
380
780
160
-
-
-
160
240
-
-
May 28
-
+++
260
720
300
720
-
-
-
1,080
180
-
-
June 2
-
+++
580
-
160
760
500
-
100
-
2,160
120
60
-
June 4
-
+++
120
—
160
2,040
-
200
-
3,260
300
20
-
June 5
-
+++
-
-
-
260
-
-
-
4,050
60
20
-
June 9
-
+++
86
-
500
2,080
-
220
80
1,080
160
200
20
June 12
-
100
-
-
500
980
-
360
-
40
100
120
40
July 2
-
+++
2,340
-
640
820
20
-
40
200
20
320
40
-------
Table 8-6 Comparison of Sludge Production
Sludges
Control
Alum, addition
Waste activated suldge
kg/d.
(mg/B)
Solid in effluent
kg/d.
(mg/2)**
Total
kg/d.
(mg/C)**
Addition as A^OH^
kg/d.
(mg/2)**
Addition as A1P04*)
kg/d.
(mg/£)**
536
(45.4)
77
(6.5)
613
(45.4)
545
(46.1)
310
(26.2)
856
(72.5)
184
(15.6)
139
(11.8)
*) Calculated value. **) Based on inflow.
- 311 -
-------
7 _,
6 -i
o
2 5
3. 4 -
s
_o
u_ 3
1 -
—I
15
8/29
20
1 5
8/30
10
Time and Date
15
20
—i—
10
8/31
Fig. 8.1 Fluctuation of Flow Rate and Phosphorus Concentration in Primary Effluent
-------
Raw Sewage
Preaeration
Tank
Primary
Settler
I
Return Sludge
Aerator
- -f P ) •+* Waste Activated Sludge
Alum Addition Bay
Final Settler
Chemical Storage Tank
Chemical Feed Pump
cu
J_
Fig. 8.2 Flow Diagram of Nishiyama STP
-------
30
J_
Z
O
Legend
Control
TKN O
NH3-N •
N03-N A,
Alum Addition
20
Z
Z
10 H
-^ V'
*\ \
/
\
XI
3/5
3/12 4/2
4/23 5/27
6/3
6/10
6/19
6/24
1975
Date
Fig. 8.3 Weekly Change of Nitrogen in Final Effluent
-------
10"
103
102
Total Ciliata (Control)
Activated Sludge Ciliata (Control)
Total Ciliata (Alum Addition)
Activated Sludge Ciliata (Alum Addition)
10
3/5 6 13 4/3 24 5/20 22 23 28 6/2 4
Calendar date
5 9 12 7/2
Fig. 8.4 Changes in Microfauna in the Activated Sludge
315
-------
CHAPTER 9. PILOT PLANT STUDIES OF PHOSPHORUS REMOVAL FROM
SECONDARY EFFLUENT TO PROTECT LAKE BIWA
9.1 LakeBiwa 317
9.2 Present Situation of Water Quality at Lake Biwa 321
9.3 Eutrophication Control and Effluent Quality Standard .... . .323
9.4 Removal of Phosphorus 327
9.4.1 BackGround 327
9.4.2 Pilot Plant for Phosphorus Removal . .327
9.4.3 Phosphorus Removal ... .330
9.5 Sludge Handling . . ... . .330
9.5.1 Alum Sludge . . . ..330
9.5.2 Thickening. 331
9.5.3 Dewatering 331
9.6 Further Research Needs ... 334
9.6.1 Loading of Phosphorus and Nitrogen on Lake Biwa 334
9.6.2 Further Pilot Plant Study 335
316
-------
9.1 LAKE BIWA
The Biwa is one of the largest lake in Japan; 680 km2 in area, and it occupies
one sixth portions of total Shiga Prefecture area.
Almost all the area of Shiga Prefecture is the basin at Lake Biwa.
Yodo-River rise from Lake Biwa is the main water resource for Kyoto, Osaka,
and Kobe. These cities are located in one of the two most densely populated and in-
dustrialized areas, Tokyo and Kansai metropolitan areas, in Japan.
Table 9.1 Geographical and Other Statistics at Lake Biwa
Location
Normal water level
Total Area
Main basin
Sub basin
Total basin area
Total coast line
Maximum depth
Average depth
Volume of water
Retention time
Shiga Prefecture
85.614 m above Osaka Bay datum, Osaka pile
low water level
680 km2
610km2 (Northern Part)
70 km2 (Southern Part)
3848 km2
240km
103.58m
41.20m
27.5 x 109 m3
5.2 year
- 317 -
-------
Lake Biwa is very important water resource for navigation, irrigation, domestic
water supply and industrial purposes.
Fig. 9.1 Water Usage from Lake Biwa and Yodo-River
(based on water rights) June 1972
M.W.
I.U.
A.U.
O.U.
7.85m3/sec.
0.18m3 /sec.
1.35 m3/sec.
0.49 m3/sec.
M.W.
I.U.
A.U.
41. 97m3 /sec.
15.20 m3/sec.
16. 80m3 /sec.
Kobe city
Katsura-river
Kyoto city
;iwa
Shiga prefecture
Ohtsu
city
f
\
M.W.
I.U.
A.U.
O.U.
3.41 m3/sec.
3.04 m3/sec.
30.00m3 /sec.
8. 70m3 /sec.
M.W.
I.U.
A.U.
0.82m3 /sec.
1.88 m3/sec.
3.25 m3/sec.
M.W.: Municipal water supply
I.U. : Industrial use
A.U.: Agricultural use
O.U.: Other use
318
-------
o.
a
WD
C
D.
_O
O
30
20
10
10--
6
5-
4
3
2 •
0
15-
10-
5-
O Hikone (Northern Part)
A Yabase (Southern Part)
n Seta River (Outflow of Lake Biwa)
X A magase Dam (21 km downstream
from Lake Biwa)
Fig. 9.2 Monthly Change in Water Quality-1
319
-------
4 --
o;
•a
o
o
(O
Environmental standard for Seta River
(so
Q
O
O
2 -•
OH
0
0.15
0.10 --
0.05 --
0.00
£
z
1.0 --
0.5 --
0.0
48
Environmental standard for lake Biwa
O Hikone
A Yabase
C1 Seta River
X Amagase Dam
(NH,-N)+(N02-N)+(N03-N)
6
28
49
10
4
10
26
28
—I—
12 1
20 23
2
21
3
11
Fig. 9.2 Monthly Change in Water Quality - 2
320 -
-------
9.2 PRESENT SITUATION OF WATER QUALITY AT LAKE BIWA
Fig. 9-2 shows the results of a water quality survey at the Biwa and at its out-
flow, the Seta River. The survey was conducted from 1973 to 1974.
The water temperature is found to stand at as low as 5 to 6 degrees Centigrade
between January and March, then start rising gradually some time in May and reach
almost 30 degrees Centigrade in August. Then, it starts down gradually. There ap-
pears no remarkable distinction in the temperature around the lake. pH value is at
approximately 7.0 to 7.5 at every point, but from summer to autumn it goes slightly
up to 8 to 9. The rise of pH-value has something to do with the growth of algae.
It seems probable that pH-value rose after CO2 underwater had been reduced
due to abundant growth of algae. The transparency of Biwa Lake water is low in its
southern part. It is approximately 2.0 meters or less all through the year. Although
it improves a little from November to January, the value does not exceed more than
2.5 to 3.0 meters. Considering the fact that the transparency exceeds 40 meters at
Lake Mashu in Hokkaido Lake Baikal, in U.S.S.R, both of which are said to maintain
the highest transparency in the world, it can be concluded that the Biwa has been
polluted to a great extent. Even in the northern part where water is said to be re-
latively clean, the transparency at Lake Biwa stands at about 5 meters. This leads us
to consider that northern Biwa is transforming from an oligotophic lake to a meso-
trophic lake. Chlorophyl is a pigment which plays a main role in the photosynthetic
reaction of plants, and is classifiable into four kinds; namely, a, b, c and d. Among
these four, chlorophyl-a is contained in every kind of algae and accordingly is used
to indicate the standing crop of algae in a water basin. The content of chlorophyl—a at
Lake Biwa, though slightly variable according to the data, was 1 to 3 micrograms
Og) per liter in the northern part and 5 to 13 micrograms per liter in the southern
part. The content of chlorophyl at lakes and marshes is reported by Ichimura and his
associates as follows:
(concentration of Chlorophyl-a)
oligotrophic lake 0.1 to 0.8 /zg/1
mesotrophic lake 1 to 5 /zg/1
eutrophic lake 10 to 60 jug/1
Chlorophyle at Lake Suwa, the most eutrophic lake in Japan, shows 30 to 60
micrograms per liter between June and September. With this in view, it is judged
that the northern part of Lake Biwa has already turned into a mesotrophic lake and
the southern part into a eutrophic lake respectively. There was a point where the
highest BOD (Biochemical Oxygen Demand) stood at 3 milligrams per liter, but in
general each point showed such a relatively low value as 1 to 2 milligrams per liter.
The environmental water quality standard for Lake Biwa has been decided to be less
than 1 milligrams per liter in terms of COD (KMnO4-COD), but at any points the
COD value in the lake water exceeds the standard and especially from August
through November it goes as high as 3 to 4 milligrams per liter. As compared to the
result of a survey in 1963 in which the annual mean COD indicated 1.12 milligrams
per liter in the southern part of Lake Biwa, it is positively presumable that the pol-
321
-------
Chlorella sp.
S. capricorrutum
A Hikone
20
2.8
3.6
5.9
*6.28
8.6
10.4
11.28
12.10
1.23
3.22
Chloiophyl-a
15
10
10
15
20
&Z.
V///
tr. (CHI)
tr. (Sel)
B Yabase
2.8
3.6
5.9
6.28
8.6
10.4
10.26
11.28
12.20
1.23
2.22
IX/XXx
V////////////////1
C Seta River
2.8
3.6
5.9
6.28
8.6
10.4
10.26
'11.28
12.20
1.23
D Zezc
E Amagase
Dam
5^
6.28
10.4
10.26
11.28
12.20
J.23
2 22
Fig. 9.3 Comparison of The Existing Volume of Algae and AGP
A: Hikone Northern Part
B: Yabase Southern Part
C: Seta Rivet... Outflow
D: Zeze Southern Part
E: Amagase Dam 21 km downstream
322
-------
lution is in progress at Lake Biwa. The reason why COD stays low in winter and high
in summer and autumn seems to be because there appears an increase of COD owing
to the growth of algae. T-P is said to have interrelations, to a certain extent, with the
degree of eutrophication, since the valute of T-P includes phosphorus in the micro-
organism grown in the same water basin. And this is why T-P shows generally a high
value from summer through autumn when COD also stays high. In general, NH4-N is
the indication that the water is polluted with aninal excreta or agricultural water.
However, since NH4-N is also oxidizable into NO2-N and NO3-N by the action of
bacteria, total inorganic nitrogen or T-N should be ingnored. Total inorgani nitrogen
stood at approximately 0.2 milligram per liter or less in the northern part of Lake
Biwa all year round, whereas in the southern part it showed as low as 0.1 milligram
per liter in autumn on the contrary to such a high value as 0.6 milligram per liter be
between February and June. This seems to have resulted from the reduction caused
by the growth of algae, as total inorganic nitrogen is normally consumed by algae.
While chlorophyl shows the existing volume of algae, i.e., the volume in existence of
algae appeared in the current lake water the AGP (Algal Growth Potential) indicates
a potential of the algal growth. The sum of the two may surely correspond to the
"total force of eutrophication" Fig. 9.3 shows relations between the present algae
concentration and AGP. AGP at Hikone (in the northern part) during the wintertime
stands at almost 10 milligrams per liter or less. This means that for the prevention of
eutrophication, AGP should be kept at less than 10 milligrams per liter during the
wintertime. To stop eutrophication in the southern part it seems necessary to keep
AGP down to 20 milligrams per liter or less. Further, at Lake Suwa which is said to
have been most eutrophicated in Japan, the water quality in terms of COD is 5 to 8
milligrams per liter, 0.2 to 0.3 milligram per liter in in T—P, about 0.20 milligram
per liter in PO4-P, 0.5 to 2.0 milligrams per liter in NH4-N and 11 to 38 milligrams
per liter in AGP (Chi.), respectively. The southern part of Lake Biwa seems to have
already been polluted as badly as Lake Suwa.
As has been mentioned above, the pollution at Lake Biwa is severe. The urgent
countermeasures are in need now so as to prevent the further pollution and eutro-
phication. Accordingly, the Japan Sewage Works Agency, having been entrusted by
the Ministry of Construction and the Shiga Prefectural Government, started surveys
and research works to prevent the pollution at Lake Biwa, especially its eutrophica-
tion.
9.3 EUTROPHICATION CONTROL AND EFFLUENT QUALITY STANDARD
Sewage Works Act states that publicly owned treatment work provide treat-
ment with effluent limitations. The effluent standard for secondary treatments such
as activated sludge process is shown in Table 9.2
- 323 -
-------
Fig. 9.4 Effects of Adding of Secondary Effluent
(Activated Sludge) or Tertiary Effluent
(Alum Coagulation)
Algae Inoculated: Chlorella SP.
Treatment Effluent Adding: 5 % (volumetric)
80
70
60
50
€ 40
"So
OH
< 30
20
10
| [ Control
V//\ Ferric chloride (50 mg/1)
*'/" treatment water
§§g^ -ditto- (100 mg/1) - ditto-
•B| Alum (50 mg/1) - ditto-
[•;.:'."•.'.•.[ -ditto- (100 mg/1) -ditto-
rillllllll Effluent of activated sludge
process
Hikone Yabase- 1 Seta River
Water sampled
on 9 May, 1973
Yabase—2
Water collected
on 29 No., 1973
Lct'tbank of
Seta River
(Under the
iron bridge
of National
Railuav)
Amagase Dam
Water collected
on 4 Oct., 1973
524
-------
Table 9.2 Sewage Treatment Plant Effluent Quality Standard
Category
H
BODS
SS
counting
Coli group
Standard Value
5.8-8.6
less than 20 mg/1
less than 70 mg/1
less than 3,000 N/ml
BOD and SS can be removed efficiently in the activated sludge process. The process
can produce the effluent that fully satisfys the effluent quality standard established
by the Sewage Works Act if only due attention is paid to the operation and mainte-
nance. However, the effluent standard is now out of date. Recently the environ-
mental water quality standard is set up in the whole Biwa Lake.
The actual allowable effluent quality is a different story from the traditional
effluent standard. The allowable effluent quality has to be determined as a standard
necessary to satisfy the environmental water quality standards established in full
consideration of various factors and their mutual relation, etc. The environmental
standards at Lake Biwa and its outflow, the Seta River are as shown in Table 9.3
Table 9-3 Environmental Water Quality Standard at Lake ESwa and Seta River
Lake fiwa
Northern Lake
Southern Lake
Seta Kiver
(Outflow)
pH
6.5-8.5
6.5-8.5
6.5-'8.5
COD
mg/1
less than
1.0
less than
1.0
less than
1.0
SS
mg/1
less than
1.0
less than
1.0
less than
25.0
DO
mg/1
more than
7.5
more than
7.5
more than
7.5
Coli. Counts
MFN/100 ml
less than
50
less than
50
less than
1000
Target
Date
*
1977
*
* Immediately satisfied after issued standard in 1972
As mentioned in the preceding chapter, the value of COD at Lake Biwa is much
greater than that of environmental standard, 1 milligram per liter, in both the
northern and southern parts. Especially during the summer period it stands at 2 to 4
milligrams per liter. In order to achieve this environmental standard at the earliest
possible time, it is in urgent need to reduce the pollution load. On the basis of the
data about the self-purification, the dilution, and the diffusion the actual effluent
quality standard should be set up. Then required waste water treatment process will
be designed. The environmental standard and the effluent quality standard on pho-
sphorus and nitrogen are scheduled to be established in the near future although the
present standard says nothing oth them.
Thus, to prevent the eutrophication, the nutrients should be removed in nearest
future. It is said that ferric salts, vitamins and carbonate also have relations with the
eutrophication beside from nitrogen and phosphorus, but as of now the requisite in-
formation is insufficient. In general, nitrogen and phosphorus are considered to be
the limiting factors of the eutrophication.
325 -
-------
The result of a study on the limiting nutrients at Lake Biwa by means of the AGP
Method is shown in Table 9.4 According to this result, since even at the same
point of Lake Biwa nitrogen plays a role of the limiting factor in one season and
then phosphorus takes its place in another season, it is considered that there exists a
variation depending on the geographical conditions, the kinds of pollution and the
meteorological conditions, etc. in the lake.
Table 9.4 Restrictive Factors of the Growth of Algae
Hikone (Northern Part)
Yabase (Southern Part)
Seta River (Outflow of
Lake Biwa)
Zeze (Southern Part)
August 1973 October
October
June Augus
August
June
August
January 1974
October 1973
Phosphorus
•
•
•
0
•
0
0
•
Nitrogen
o
o
o
•
•
0
•
o
• Stimulate the growth of algae
o Does not stimulate the growth of algae
Accordingly, it will be known that the removal of both nitrogen and phosphorus is
desirable for the complete control of the eutrophication. However, due to the ex-
istence of bacteria and algae (blue-green algae) which fix it from the air, it is difficult
to control the nitrogen efficiently. Hence, studies were herein conducted before
everything on the removal of phosphorus.
Now, there arises a question; to what extent the concentration of phosphorus
in the effluent water from a sewage treatment plant should be lowered? This ques-
tion can be answered rather easily if the AGP is applied.
By changing alum dosage, effluents which contain several concentrations of
phosphorus are prepared. Then the effluents are dilluted with the least eutrophicat-
ed lake water at a certain ratio, say 20 times. When AGP is related with the phos-
phorus concentration in the prepared effluent, allowable maximum phosphorus con-
centration would be determined. Fig. 9.4 shows the results of the examination.
As is shown in the figure, when an amount of either alum or ferric chloride is
dosed to reach its concentration of 100 ppm, AGP in the mixture is always kept less
than 20 mg/1. For this circumstance, phosphorus concentration in the prepared
secondary effluent is 0.03 mg/1. Judging from this result, it is considered that the
eutrophication in the lake water may hardly be promoted if PO4-P as the tertiary
treatment water is set at lower than 0.03 to 0.02 milligram per liter.
- 326 -
-------
9.4 REMOVAL OF PHOSPHORUS
9.4.1 BACK GROUND
For the purpose of phosphorus removal from urban sanitary sewage, technical-
ly and economically feasible processes are the following
a. Luxury biological phosphorus uptake process
b. Coagulant dosing process
c. Lime precipitation process
d. Alum precipitation process
It was reported that if the luxury uptake process was successfully operated, over 80
percent of the total phosphorus could be removed. However it is not easy or not
always possible to keep the process at the optimum condition. Sometimes the
process may be of success in the luxury uptake but sometimes not.
By means of dosing coagulant to an aeration tank, the phosphorus removal
through the secondary treatment process improves considerably. At first we believed
that this was an economical way to grade up the present facility. We tried to
examine performance of this process on a pilot plant. When three times aluminum in
mol ratio to phosphorus were dosed to the aeration tank, about 60-80 percent of the
phosphorus existed in inflow sewage were precipitated. If this amount of alum was
added, its concentration in the mixed liquor would be about 150 mg/1. Even though
such the high dosage as 150 mg/1, the secondary effluent still contained 0.2 ~ 0.5
mg/1 of phosphorus. This concentration was not satisfactory for the Biwa Lake
water. Higher phosphorus removal required more alum dosage. A new problem rised;
that was retardation of biological activity. Too much alum in the biological process
resulted in poor BOD removal. Thus, we quitted this process and came to the
decision that an independent advanced plant should be placed to cope with the
phosphorus problem.
The most popular and effective coagulant for this purpose is lime. Sludge pro-
duced from the lime precipitation process can be easily dewatered by ordinal
devices. This is one of the important advantage in selecting any unit processes.
Disadvantages being associated with this process are difficulty in handling lime, and
scaling in pipes.
The alternative is the alum precipitation process. For the phosphorus removal
alone, alum is as effective as lime. Alum is easy to handle and is not scaling. However
on the other hands, alum sludge is hard to dewater.
Finally we came to the conclusion that the alum process was selected for the
case of Lake Biwa's tertiary purpose. It is not because we like the advantages of the
alum process more, but because we like the disadvantages of the lime process less.
There was no news of success in dewatering sole alum sludge. Development of sludge
dewatering engineering and establishment of design parameters for the alum process
were the next step to approach the final goal. This was a story untilthis pilot plant
was placed in Otsu sewage plant.
9.4.2 PILOT PLANT FOR PHOSPHORUS REMOVAL
A flow sheet of the pilot plant is shown in Fig. 9.5 The hydraulic capacity is
500 cubic meters per day. In this flow rate, design detention time is 15, 30, and 150
327
-------
Fig. 9.5 Flow Diagram of Coagulation Process
INJ
OC
Influent
Flush mixer tank
Measuring tank / \
Floculation
tank
Settling tank
Receiving tank
Coagulant
injection
pump
Poliner injection pump
Sludge return
pump
Coagulant storage
tank (Alum.)
Polimer
storage tank
Sludge
pump
Dewatering
process
Sludge thickner tank
Effluent holding
tank
-------
Fig. 9.6 Flow Diagram of Sludge Handling Process
Inflow
Sludge
thickner
tank
Coagulation dissolve tank
Handling tank
Coagulant pump
O
Handling tank Sludge pump
Centrifuge
Land disposal
Supernatant Dewatermg
sludge hopper
-------
minutes for the rapid mixing tank, the flocculation tank, and precipitation tank
respectively.
Into the center of the rapid mixing tank, liquid alum and polymer are fed at a
certain rate through chemical feeding pumps. A small amount of the polymer is
helpful with alum flocculation.
In order to save the alum, some portions of the precipitated alum sludge are to
be returned from the precipitation tank to either the rapid mixing tank or the floc-
culation tank.
In future, automatic control system will be introduced so that the alum can be
dosed proportionally to phosphorus concentration. Thus, we will be able to examine
several aspects on the automatic control practice.
9.4.3 PHOSPHORUS REMOVAL
In general, a large plant requires much more alum that of theoretical requirement
due to improper design. Our main concern is to find the optimum process conditions
under which phosphorus can effectively be removed by a small amount of alum
dosage. Up to the present, it is found that when alum is dosed as much as 13.6 mg/1
(or mol ratio to phosphorus 5 to 1) about 90 percents phosphorus are removed.
The pilot study is now under ways for the purpose of finding:
(1) A relation between sludge producing rate and alum dosage
(2) a relation between SS removal rate and alum dosage
(3) effect of return sludge on phosphorus removal and on alum saving
(4) optimum rapid mixing and slow mixing
(5) polymer dosing rate and dosing point.
9.5 SLUDGE HANDLING
9.5.1 ALUM SLUDGE
An increase in alum dosage results in an increase in phosphorus removal. We
can cope with any requirement for high phosphorus removal. Removing the
phosphorus in a rather easy job. One of the big problems included in the alum
precipitation is that a large amount of sludge is produced. The amount is directly
proportional to the alum dosage. Through the course of the present pilot alum
process, in every 500 cubi: meters influent, 3.4 cubic meters sludge are produced.
Therefore when 1 million cubic meters raw sewage is treated in the actual plant,
daily sludge production rats will be 7000 cubic meters. A special attention should be
paid to this large number. A success in phosphorus removal from Otsu's effluent
will be entirely dependent on the sludge handling capability.
The kinetics for the alum precipitation process is not yet completely clear. It
seems probable that two reactions may be concerned with this process; (1) alum
combines directly phosphorus and forms floes of aluminum phosphate, and (2)
phosphorus is absorbed at the surface of aluminum hydroxide which is formed
through a reaction between the alum and alkalinity.
Phosphorus (total-p) concentration in the secondary effluent from the present
Otsu sewage plant is as low as 1 mg per liter. Suspended solid concentration ranges
from 3 to 5 mg per liter. Volatile solid contents are about 35 percents of the total
suspended solids. This means that large portion of the precipitated sludge is
330
-------
aluminum compound.
9.5.2 THICKENING
Underflow concentration in the precipitation tank is no greater than 5000 mg
per liter. The sludge is very hard to thicken; under the quiescent condition, by
gravity, during 24 hours, an increase in solid concentration is about 30 or 40 per-
centration never exceeds 10000 mg per liter by the gravity thickening method.
9.5.3 DEWATERING
The solid particles in the sludge are very fine and they stay as soil or gell in it.
Leaf tests do not show any capability for vacuum filters to dewater the sludge. It is
observed that the fine particle included in the alum sludge pass through the filter
cloth when a Buchner funnel test is performed. Magnitude of the drainability or
filterbility can not be determined in the laboratory Buchner funnel test.
We give up examining possibilities of success in dewatering by using the vacuum
filter. Our interests are shifted to centrifuge dewatering. It may be the only device
which has possibility to yield satisfactorily moistured sludge cake from alum precipi-
tant. Meanwhile, our laboratory research shows that if the polymer is properly
selected and properly dosed, a certain centrifuge will do the job. Polymer is a very
important factor to affect centrifuge performance. Our staffs moves up from the
laboratory to the field where the pilot plant is located. Fig- 9.6 is a flow sheet of
the plant. The dewatering study continues with this plant now.
The findings are summerized in Table 9.5. The tests from run # 1 to # 5 are
for selecting most suitable polymer and those from # 6 to # 9 are for optimum ope-
rational conditions of the centrifuge.
The design specification of the pilot centrifuge are as follows;
Maximum Power 3200 G
Maximum Revolution Speed 6000 RPM
Motor Output 3.75 KW
Capacity 500 liter/hr.
The folio wings are concluded from the pilot study:
(1) More than 96 percents of the suspended solid are recovered and moisture con-
centration in the dewatered sludge cake is 90% at average, (85% at minimum). The
dewatered sludge can sustain own shape by itself on a flat plate. This can be handled
by hands or a shovel easily.
(2) An increase in the polymer dosage rate does not improve the moisture concent-
ration. On the basis of dry solids, 0.5 percents are the optimum dosing rate.
(3) If the sludge feeding rate is increased, the moisture concentration in the de-
watered sludge is kept fairly constant value, 90%, and the SS recovery rate is decrea-
sed. The same is observed when difference of revolution speeds between the bowl
and the conveyer is increased.
(4) Whether cathionic or anionic is not an important factor. The effectiveness of
the polymer is not dependent of its ion charge.
331
-------
(5) Solid concentration of the fed sludge is a main factor on the centrifuge per-
formance. The thicker is the fed sludge, the less is the moisture contents of the de-
watered sludge.
(6) With lower bowel dam height in the centrifuge than with higher, less moistured
sludge are yielded. The pilot centrifuge is designed to adjust the dam height at 4
levels. With the lowest level of the dam, least moistured sludge are produced. It is
around 85 percents.
The value of 85 percents moisture concentrations in the dewatered sludge is
not perfectly satisfactory. Our efforts will be concentrated at reducing the number
to about 80 percents. Selection of proper polymer is a way to approach the purpose.
Another way is to stimulate manufacturers to provide a proper centrifuge.
One of the important thing that we should know is how Acrylamid, main com-
ponent of the polymer, affects the environment. When supernatant is returned to
the secondary process, at present moment, we are not sure what happens with the
secondary effluent. We are going to examine bio-degrability of the polymer returned
to the aeration tank.
Commonly it is reported that alum recovery is not economically feasible.
However, from the stand point of natural resource saving, our interests are still kept
on developing the alum recovery engineering. Sulfic acid process could be in higher
potential.
- 332
-------
Table 9.5 Summary of Sludge Dewatering Performance
Test
No.
1
2
3
4
5
6
7
8
9
Spec, of Machine
Revolution
(r.p.m)
5000
5000
5000
5000
5000
5000
5000
5000
5000
Dam
No.
4
4
4
4
4
4
3
3
3
Revolution
Difference
(r.r.m)
6
6
6
6
6
10
6
6
15
Influent
Density
(%)"
0.6260
0.6230
0.4800
0.6970
0.6770
0.6200
0.9190
0.9740
0.8810
Sludge
loading
(1/hr)
400
400
400
400
400
400
500
500
700
Solid
loading
(kg/hr)
2,505
2,490
1,921
2,788
2,732
2,480
4,595
4,870
6,167
Filtrate
Density
(%)
0.0245
0.0220
0.0136
0.0146
0.0090
0.0450
0.0113
0.0084
0.0300
SS
Recovery
ratio
96.09
96.47
97.17
97.91
98.67
92.74
98.77
99.91
96.59
Moisture
(%)
90.07
89.95
88.79
89.21
89.36
90.79
88.14
86.82
88.54
Coagulant
Density
(%)
0.05
0.05
0.05
0.05
0.05
0.05
0.10
0.05
0.10
Volume
(1/hr)
30
55
34
31
31
30
17
80
56
FA/SS
(%)
0.600
1.105
0.916
0.556
0.568
0.6048
0.3680
1.643
0.908
Sort
A
B
C
D
E
A
B
C
B
U-l
I
A: N0-75°(nonion)
B: A-101 (anion)
C: N-800 (nonion)
D: SS-200 (nonion)
E: C-OllK(cation)
-------
9.6 FURTHER RESEARCH NEEDS
9.6.1 LOADING OF PHOSPHORUS AND NITROGEN ON LAKE BIWA
Kinki Branch Office of Ministry of Construction conducted intensive study on
nutrient loading on Lake Biwa in the last year as shown in Table 9.6 and 9.7.
Table 9.6 Total Phosphorus Loading*
Domestic Waste
Water
Industrial Warte
Water
Warte-water from
eivestock Yard
Discharge from
Pady Field
Discharge from
Frest etc.
Total
1970
Load (kg/d)
174.0
21.6
32.8
40.3
66.3
335
Share (%)
51.9
6.4
9.8
12.0
19.8
100
1980**
Load (kg/d)
247.5
125.6
74.3
41.9
66.3
555.6
Share (%)
44.6
22.6
13.4
7.5
11.9
100
Table 9.7 Total Nitrogen Loading*
Domestic Waste-
water
Industrial Waste-
water
Waste-Water
livestock yard
Paddy field
Frest
Total
1970
Load (kg/d)
1960.5
801.5
111.5
974.6
1264.9
4713
Share (%)
33.1
17.0
2.4
20.7
26.8
100
1980**
Load (kg/d)
1854.5
1974.9
244.6
1181.8
1264.9
6520.7
Share (%)
28.4
30.2
3.7
18.1
19.4
100
*(1) Table does not include load from well water source because of
uncertainty of measurements.
(2) This figure are projected before treatment.
** This is estimated based on economic development plan of Shiga Pufectural Govern-
ment.
334 -
-------
The water quality of lake Biwa at present are mentioned before, it will be expected
that nutrients loading exceed a certain amount very much such as critical or dan-
gerous level as proposed Vollenweider. The rate of effluent to total discharge of
Lake Biwa to downstream is around 10%, so it is very important to remove the
phosphorus to protect lake water.
Unfortunately available data are very scarce on water quality, flow pattern, diffusion
characteristies and budget of nutrients in the lake, much research works are needed
in this fields.
9.6.2 FURTHER PILOT PLANT STUDY
Pilot plant study for Lake Biwa is 4 Years project, then it will be completed in
1978. First of all, removal of phosphorus by alum precipitation are examined, and
dewatering of alum sludge are found to be possible by centrifuge. All possible
alternatives to remove nutrients from wastewater should be projected to examine
including cost effectiveness study in this project.
Reference.
1) J.S.W.A. Survey on the Pollution in Lake Biwa in 1972, 1973.
2) An Approach to a Relative Trophic Index System for Classifying Lakes and
Reservoirs, Working Paper No. 24. Pacific North West Environmental Research
Laboratory U.S. EPA.
- 335 -
-------
Fourth US/JAPAN Conference
on
Sewage Treatment Technolgy
Paper Annex to No. 4
CASE STUDIES ON PCB POLLUTION
October 29, 1975
Washington, D. C.
Ministry of Construction
Japanese Government
336 -
-------
CASE STUDIES ON PCB POLLUTION (CONTINUED)
- 337
-------
2.2 CASE STUDIES ON PCB POLLUTION (continued)
Environmental pollution of PCBs was first recognised in
Europe followed by the United States then Japan. Results of
field investigations demonstrated that PCB pollution in organ-
isms inhabiting the natural environment was at a^evre level.
In Japan, analytical results indicating concentrations of resi-
dues in trild animals were first reported in 1971. In January
of 1972, a standard method for the analysis of PCBs was establ-
ished by the reseaoh group of the Ministry of Health and Wel-
fare, whereby the uniform analysis of PCB residues in wild ani-
mals was realised.
71.
A national survey Governing environmental pollution of PCBs
was conducted from May to December, 1972. During this period,
the water quality of 1,084 locations and bottom sediments samp-
led from 1,445 places was inspected. Canvassing the agricult-
ural industry, PCB analysis were carried out for samples of
soil and rice taken from 88 locations throughout the country,
while similar analysis were conducted for 559 samples of fish-
eries products taken from 110 aquqtic regions. Summaries of
these results are shown in Table 4» 5 and 6. Prom 1973 to
March, 1974, l,28l samples were collected from 282 aquatic re-
gions for water quality analysis (208 rivers; 28 harbours; 46
ocean regions), while 1,7^9 samples of bottom sediments were
collected from 354 aquatic regions (258 rivers; 38 harbours; 58
ocean regions) as well as 3,369 samples representing aquatic
biota.
In Japan, the accumulation of PCBs in the human body can be
surmised and evaluated on the basis of analytical results of
residues detected in human milk. Such a survey was taken
throughout the country during the three year period from 1972
to 1974» and the results are summarised in Table 7, A summary
of regional differences based upon the results of the 1974 sur-
vey is presented in Table 8, and indicates that the PCB content
338
-------
of human milk tended to be highest in those regions described
primarily as fishing villages and lowest in farm inhabitants.
Table 4 Results of the Survey on PCB Pollution (Water Quality
and Sediments)
PCB
content
(ppm)
Industr-
ies
using
PCB
Sewage
treat-
ment
plants
Waters
nearby
factor-
ies
Public
Waters
Total
Water Quality
0.01 0.01
or or
less more
78 13
125 0
76 4
785 3
1,064 20
Sub-
91
125
80
788
1,084
Sediments
1 1.1 11 51 100 500
or S S S * or
0 19 10 5 11 9
------
26 24 15 7 1 4
1,216 73 20 2 3 0
1,242 116 45 14 15 13
Sub-
total
54
-
77
1,314
1,445
Grand
Total
145
125
157
2,102
2,529
Table 5 Results of the Survey on PCB Pollution (Soil and
Agricultural Products)
PCB Concentration
less than 0.01 ppm
0.01 0.10 ppm
0.11 1.0 ppm
1.1 10.0 ppm
10.1 100.0 ppm
more than 100.1 ppm
Total
Number of Soil
Samples
35 ( 40$
21 ( 24$
19
6
3
4
21$
7$
3$)
5$)
88 (100$)
Number of Unhuller".
Rioe Samples
26
5
1
1
79$
15$
3$
•jrg
339
-------
Table 6 Results of the Survey on PCS Pollution
(Fisheries Products) (1972)
PCB
Concentration
(ppm)
Sea Water
Fresh Water
Total
0.09
or
less
(34)
155
(15)
21
(30)
176
0.1
S
0.4
(38)
175
(44)
63
(40)
238
0.5
5
0.9
(12)
53
(23)
33
(14)
86
1-2
(11)
48
(13)
19
(11)
67
3
(2)
11
(1)
2
(2)
13
more
than
3
(3)
14
(4)
5
(3)
19
Total
(100)
456
(100)
143
(100)
599
Table 8 Frequency Distribution of PCB Concentration in Human
Milk in Urban, Agricultural and Industrial Eegions(l972)
Concent-
ration
(ppm)
0.009
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
0.2
Total
Mean
Median
Total
(Cumulat-
ive %)
67( 12.1)
86( 27.5)
148( 54.1)
90( 70.3)
77( 84.2)
33( 90.1)
14( 92.6)
25( 97.1)
6( 98.2)
4( 98.9)
6(100.0)
-
556
0.028
0.023
Urban
Residential
Areas
22
37
74
41
36
15
6
8
3
-
2
-
244
0.028
0.024
Farm
Villages
34
31
49
23
23
6
5
2
1
1
1
-
176
0.023
0.020
Fishing
Villages
8
13
17
22
15
7
3
11
2
3
3
-
104
0.037
0.031
Industrial
Vicinities
3
5
8
4
3
5
-
4
-
—
-
—
32
0.031
0.025
340
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PLANNING FOR URBAN RUNOFF CONTROL UNDER COMPREHENSIVE
WATER QUALITY MANAGEMENT SYSTEM
Walter S. Groszyk
Deputy Director, Water Planning Division
Environmental Protection Agency
East Tower, Room 815 - WH-554
401 M Street, S.W.
Washington, D.C. 20460
ABSTRACT
(
This paper summarizes the approach being developed by the U. S. Environmental
Protection Agency for the abatement of urban storm runoff. The approach features the
development, at the local or regional level, of specific management practices to
control runoff. These practices emphasize non-capital intensive methods of minimizing
the pollutant loading of runoff and are formulated through a comprehensive areawide
planning effort that assesses the dimensions of the runoff problem, the water quality
effects, and abatement needs.
TEXT
The United States Environmental Pro-
tection Agency through the States and
cities conducted a survey of the estimated
construction costs to abate storm sewer
pollution. This survey of needs amounted
to nearly $250 billion in current dollars.
While the number does not generally reflect
any engineering plans or detailed surveys,
its rough magnitude is staggering and
beyond the digestive capacity of the Fed-
eral budget. There is simply no foreseeable
way that the Federal Government would be
able to finance a construction program of
this size for this problem. It exceeds by
tenfold the total program of landing a man
on the moon, and is nearly ten times the
total annual contract construction value in
the U.S. gross national product for 1973.
As an additional perspective, the estimated
costs, in this same Needs Survey, for con-
structing treatment plants, interceptor and
collection sewers, and controlling combined
sewers totalled approximately $100 billion,
with the total need becoming nearly $350
billion.
Areawide Planning
Under the Federal Water Pollution Con-
trol Act, an areawide planning program is
to be conducted in urban-industrial areas
with significant water quality problems.
This planning program has just begun, and
at the present time planning is under way in
149 areas at a cost of $163 million. This
planning covers many of the largest cities
of the United States, including New York,
Philadelphia, Chicago, and Detroit. These
plans will eventually cover the entire
United States. Presently, about 45% of
the population and 11% of the land area
of the United States are covered by area-
wide, planning.
Areawide planning is also called 208
planning, after the number of the section
of the Federal Water Pollution Control Act
which authorizes it. Areawide planning is
quite unique for three reasons. It is
expected to be the largest planning pro-
gram ever funded by the Federal Government;
all the financing for the program comes
from the Federal Government; and the law
requires that the plans be implemented.
Areawide planning conducted for a local
area is a comprehensive plan. The plan
covers both point and nonpoint sources of
pollution. It includes: initial facilities
planning for municipal sewage treatment
works; an identification of industrial pol-
lution control requirements; and the
629
-------
identification of practicable methods and
procedures for the control of nonpoint
sources of pollution, including runoff from
agricultural, silvicultural, mining, and
construction activities.
The planning effort is conducted at
the city and county level, and is under the
direction of the chief elected officials of
local government within the planning area.
This will assure that plan development
reflects the views of the government
officials who will operationally implement
the plan. The initial plan is to be comp-
leted not later than three years after the
planning agency has been approved by EPA.
At the time of completion, EPA is required
to approve the designation of the manage-
ment agencies who will carry out the plan.
The planning agency continues to function
and develops revisions to the plan as they
are required.
This stress on locally originated
planning conducted under the direction of
locally elected officials reflects an
appreciation that levels of abatement more
stringent than those required by nationally
applicable effluent guidelines for industry
or uniform secondary treatment for munici-
palities can often best be addressed by
examining the specific pollution problems
in that area which remain after national
levels of control are applied; assessing
the institutional and financial capabili-
ties that exist or can be developed to
abate the sources of this remaining pollu-
tion; and then making the tradeoff's
between alternative control methods to
develop the most effective and reasonable
way of reaching the water quality
objectives.
Best Management Practices (BMP's)
The Environmental Protection Agency,
to assist planning agencies in making these
tradeoff's, is developing informational
guidelines outlining different methods and
procedures that can be used to abate non-
point source pollution including urban
runoff. These informational guidelines are
called Best Management Practices or BMP's.
A BMP is not an "end of the pipe" techno-
logical control level, but rather is a way
of doing business. It is directed to the
activity being conducted; as an example, it
may indicate that sediment runoff from a
farmer's field can be reduced by changing
the manner in which the farmer plows the
field. BMP's are being developed for all
categories of nonpoint source pollution,
including urban runoff.
BMP's for a particular category
present an array of alternative practices
with varying economic costs and efficiency
rates. The practices often identify cli-
matological or topographical suitability.
From this inventory of BMP's we expect the
planning agencies to select those practices
which most fit the abatement needs of their
area. The planning agency is not required
to use any of the BMP's but may develop an
equivalent BMP on its own. While Best
Management Practices are generally con-
cerned with non-capital intensive methods
of control, they are not exclusively so.
A planning agency may also, after analysis,
determine that the most effective and
economic way to achieve water quality goals
for that area is through the construction
of facilities and structures.
BMP's and Urban Runoff
Our present perception is that it is
neither necessary nor possible to treat all
storm waters. A receiving water is subject
to stresses caused in part by various
natural and uncontrollable occurrences.
Many streams experience difficulty during
the low flow and high temperature period
of later summer. Wet weather conditions
represent yet another period of stress.
The true extent of the storm water
problem is largely unknown and the lack of
any extensive historical studies or con-
cern makes it difficult to characterize.
Considering the area and route that
urban runoff takes, it is not surprising
that this runoff contains substantial
amounts of organic material, inorganic
material, inorganic solids, nutrients,
heavy metals and micro-organisms. The
impacts from this runoff are often
increased oxygen demand, high turbidity,
and increased eutrophication rates. Addi-
tionally, the impact of heavy metals on the
aquatic environment has to be considered.
The total pollutant load in storm-
water, during storm runoff periods, can be
greater than the pollutant load discharged
from municipal treatment plants during dry
weather. This could preclude meeting water
quality standards regardless of the degrees
or types of treatment afforded dry weather
630
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wastewater flows.
Related problems resulting from
unregulated, or poorly regulated, runoff
are accelerated erosion of land area and
stream banks, sedimentation of channels,
increased flooding, increased potential for
public health problems and deterioration of
aesthetic quality.
Assessing the impact of stormwater run-
off is not easy. Part of the difficulty
lies in the variability of stormwater run-
off. The quantity and quality of storm
overflows, for example, can vary with
respect to storm characteristics, antecedent
conditions, time, location, degree of urban-
ization and other factors. This variability,
the differing problems in new and expanding
urban areas compared with existing areas,
and the scarcity of information concerning
stormwater impact on receiving waters pose
challenges to the formulation and admin-
istration of an effective management program.
Some of the examples of these varying
factors are that: loading rates are lowest
in commerical areas; BOD 5 and COD concentra-
tions are lowest in residential and heavy
industrial areas, while the COD concentra-
tion is highest in commerical areas; cadmium
concentrations are relatively uniform across
all areas; chromium, nickel, and copper are
lowest in residential areas, with lead con-
centrations lowest in heavy industry areas;
and finally, and surprisingly, there is no
significant difference between land use
category and fecal coliform count.
From the analysis of the specific prob-
lem parameters with respect to water quality
and with a correlation as to the likely land
use areas and the sources of the problem,
the planning agency can then analyze which
BMP's it might apply to control the problem.
BMP's within an urban/suburban area
include source regulation, collection system
control, treatment, and an integrated
approach using all three. Source control is
defined as those measures for preventing or
reducing stormwater pollution that utilize
management techniques (e.g., good house-
keeping methods) and stormwater detention
within the urban drainage basin before
runoff enters the sewerage system.
Collection system control includes all
alternatives pertaining to collection
system management, such as use of sewers as
detention facilities. Treatment, including
storage, is another technique. The term
storage refers to stormwater being retained
for the purpose of treatment as opposed to
storage used in source control to attenuate
the rate of runoff. Flow attenuation is
concerned directly with runoff as it moves
over the surface of the urban area; i.e.,
the initial collection system. Flow attenu-
ation, in an hydrologic sense, means to
increase the time of concentration and
decrease the magnitude of the peak runoff.
In terms of water quality this means that
runoff velocities are reduced and less pol-
lutants are entrained. Also, less erosion
results because reduced runoff velocity
reduces the erosion force. Moreover, large
volumes of water are not allowed to rapidly
accumulate at constrictions, but flow at
reduced rates over a longer period of time,
thus reducing the possibility of localized
flooding. An integrated approach might
include source control to help reduce pol-
lutant loads and runoff rates; collection
system control (sewerage) to reduce infil-
tration and to attenuate the runoff; and
treatment as a final stop where required
to meet water quality objectives.
The management goals become:
1. Prevention and/or reduction of
pollution.
2. Detention or retention of runoff.
3. Treatment of runoff.
An additional goal that should not be
overlooked is reuse of stormwater runoff.
Reuse of stormwater places urban runoff in
the resources category. It should be con-
sidered in those areas that can benefit from
groundwater recharge and supplemental sup-
plies for both potable and nonpotable use.
The goal of the planning approach is
to provide sufficient pollutant reduction
to meet water quality objectives at a
minimum cost. BMP's for urban runoff
should stress source and collection system
management, and reuse where applicable.
Treatment should be resorted to only when
all other lower cost methods have failed to
provide sufficient pollutant reduction.
Urban runoff management should
initially emphasize the new urban areas.
These new areas include land that is in the
process of becoming urbanized. These are
areas that allow for the greatest degree of
631
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flexibility of approach in addressing the
long-term problems. At a minimum, urban
runoff pollution must be contained to pre-
sent problems. Once contained, then
emphasis can shift to problems associated
with existing areas. Of course, for this
approach to be effective, complete area
coverage is required and the approach
should be implemented as appropriate
throughout the entire planning area.
For a BMP to be considered as a best
management practice, it must meet certain
general and specific criteria. Factors
that need to be addressed within a BMP
include, but are not limited to, the
following.
A BMP must be compatible with the
hydrology and meteorology of the planning
area. The frequency, intensity, duration,
and surface area extent of precipitation
must be addressed; also, infiltration
rates, depression storage, and runoff
rates. Groundwater must be considered in
relation to recharge areas and levels, and
effect on stream channels fed from ground-
water.
Runoff from snowmelt in some areas of
the country (for example, in parts of the
West) produces the major portion of the
annual runoff. An important factor in
considering snowmelt is the temperature.
Other factors to be addressed are wind and
humidity.
Topography, of course, is a factor
that must be considered. A BMP must be
compatible with the slope, length of basin,
and type of surface cover of the planning
areas.
Geology is another factor to be
addressed. Soil types vary widely across
the country. A BMP must consider and be
compatible with this variable.
The specific examples of BMP's that
can be examined are to be considered as
being site-specific and are not to be con-
strued as being applicable nationwide.
Source Control
Some examples of source control are:
1. Street sweeping or control
through housekeeping.
2. Sewer flushing to reduce first
flush effects.
3. Detention basins.
4. Rooftop storage and parking
lot storage.
5. Porous paving, to increase
infiltration.
Collection System Control
Some examples of collection system
control are:
1. Use of existing sewerage as
detention facilities.
2. Use of swirl concentrators.
Treatment
Two examples which have been studied
and have been found feasible for storm-
water treatment are:
1. Micro-straining with air
floatation.
2. Contact stabilization.
Institutionally, we expect the
planning process will work in the follow-
ing manner.
The planning agency staff will assess
the magnitude and extent of the urban pol-
lution problems. These will be presented
to the public and any advisory groups to
ensure that a basic understanding of the
problems is shared by all.
The staff will then formulate water
quality goals based on protecting bene-
ficial uses of water. These will be
discussed with the public and will be
presented to the advisory committee. The
advisory committee overseeing the develop-
ment of the plan will select the approach
which best meets the goals.
Proposed criteria for controlling
urban runoff pollution will be prepared
by the staff in consultation with the
public. An inventory of alternative BMP's
which meet the proposed criteria will be
made.
632
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The staff will evaluate and make
initial selection of those BMP's which
meet the water quality objectives, and the
public and advisory group will decide which
of the BMP's are institutionally and
economically acceptable. Final selection
of the BMP's will be made then by the staff.
After the urban runoff problem has
been assessed, runoff reductions to help
meet target load allocations achieved by
the use of BMP's often need to be trans-
lated into ordinances or regulations.
Within EPA, we believe the use of the
areawide planning process together with the
systematized assessment of BMP's offers an
attractive alternative to total reliance
on capital facilities for control of urban
runoff. The planning process has just
begun, and we would like to report at a
future conference on the results from this
effort.
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CONTROL OF WATER POLLUTION THROUGH ISSUANCE OF
DISCHARGE PERMITS, IMPLEMENTATION OF P.L. 92-500
R. B. Schaffer
Director, Permits Division
Office of Enforcement
U.S. Environmental Protection Agency
Washington, D. C. 20460
OBJECTIVES OF THE NPDES PROGRAM
On October 18, 1972, the Amendments to
the Federal Water Pollution Control Act es-
tablished the National Pollutant Discharge
Elimination System (NPDES). With the enact-
ment of this new legislation Congress has
stated that it is the National goal that
the discharge of pollutants into navigable
waters be eliminated by 1985. As an interim
goal it is stated that there be attained by
July 1, 1983, water quality which provides
for the production and propagation of fish,
shellfish and wildlife and provides for the
recreation in and on the water.
Any permit issued under the National
Permit System will impose on a discharger
of pollutants from a point source certain
requirements designed to attain the goals
of the Act. Every discharger must make
application for a permit and in so doing,
provide the permitting authority with data
on the discharge. Each issued permit will
meet effluent limitations, wate?: quality
standards, new source performance standards
for new plants, and toxic pollutant stand-
ards. Facilities discharging into a muni-
cipal waste treatment facility do not re-
quire a discharge permit, but the discharger
must comply with pretreatment standards
promulgated under the Act. Permits will
require the discharger to monitor the dis-
charge, to keep records of monitoring ac-
tivities and report periodically on what is
occurring with regard to the discharge.
THE EFFLUENT LIMITATIONS
The new Act provides for uniform ef-
fluent limitations for industrial categories
and achievement dates. Congress set two
interim dates of July 1, 1977 and July 1,
1983, by which different levels of treat-
ment are to be reached. It is a timetable
based on advances in technology.
For all discharges other than publicly
owned treatment works, not later than July 1,
1977, effluent limitations are to be achieved
which represent the application of the "Best
Practicable Control Technology Currently
Available." At the same time, all publicly
owned waste treatment facilities must uti-
lize ''secondary treatment" and, if an indus-
trial discharger sends its waste through a
publicly owned treatment works, certain "pre-
treatment standards" must be met. An addi-
tional requirement is that by the July 1977
date, effluent limitations may be imposed so
that any state law will be met. Not later
than July 1, 1983, effluent requirements
must be met which represent the "Best Avail-
able Technology Economically Achieveable"
and, for publicly owned waste treatment
facilities, which represent the application
of the "Best Practicable Waste Treatment
Technology.'1 Any other applicable pretreat-
ment standards must also be attained by that
date. Special standards of toxic substances
must also be observed for both the 1977 and
1983 targets.
The target dates are 1977 and 1983;
they are the outside limits for compliance.
The Act envisions that in meeting effluent
limitations there will be stages of compli-
ance including attainment of levels of sub-
stantial improvement even before these dates.
Therefore, most permits will impose a
schedule of remedial measures. This sche-
dule will appear as a condition set out in
an NPDES permit.
The Agency has requested authority to
extend the 1977 date on a case-by-case basis
for publicly owned treatment works. However,
we do not feel it is necessary to extend the
date for other dischargers nor do we expect
the National Commission on Water Quality to
recommend it to Congress.
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BEST PRACTICABLE CONTROL TECHNOLOGY
AND BEST AVAILABLE TECHNOLOGY
The Act charges the Administrator with
the task for publishing regulations provid-
ing "Guidelines" for effluent limitations
for point sources after he has consulted
with the appropriate Federal and State
agencies and other interested persons. These
effluent limitations are the ones which
shall require the application of the Best
Practicable Technology by 1977, and Best
Available Technology Economically Achieve-
able for the 1983 target dates. Two things
will be identified in the regulations.
First, they will give meaning to the
terms "Best Practicable" and "Best Avail-
able" when applied to various categories
of industries. In defining "Best Practic-
able" and "Best Available" for a particular
category, such factors as the age of the
equipment and facilities involved, the pro-
cess employed, the engineering aspects of
the application of control techniques, pro-
cess changes, and non-water quality environ-
mental impact (including energy require-
ments) will be taken into account. In
assessing "Best Practicable Control, a
balancing test between total cost and ef-
fluent reduction benefits is to be made.
Cost is also a factor in determining "Best
Available." "Best Available" technology is
the highest degree of technology that has
been demonstrated as capable of being de-
signed for plant scale operation, so that
costs for this treatment may be much higher
than for treatment by "Best Practicable"
technology. Yet economic feasibility will
also be a factor in interpreting "Best
Available" treatment. Cost effectiveness
for either standard is to be confined to
consideration of classes or categories of
point sources and will not be applied to
an individual point source within a cate-
gory or class.
Second, having interpreted "Best Prac-
ticable" and "Best Available" guidelines
will be published which will determine what
"Effluent Limitations" are to be imposed on
dischargers. In these guidelines the degree
of effluent reduction attainable through the
application of the "Best Practicable Control"
and "Best Available Technology" in terms of
amounts of constituents per unit of produc-
tion. These guidelines can then be applied
in setting specific effluent limitations on
dischargers.
The Agency will promulgate these various
standards and guidelines for some 200 classes
and categories of dischargers.
TOXIC POLLUTANT EFFLUENT STANDARDS
The Act requires the establishment of
effluent standards or prohibitions controll-
ing toxic pollutants. Toxic pollutants are
defined as those pollutants, or combinations
of pollutants which, after discharge and
upon exposure to any organism either directly
or indirectly, will "on the basis of infor-
mation "available" cause death, disease, or
other abnormalities in the organism or its
offspring. The drafters of the Act had in
mine certain substances such as mercury,
beryllium, arsenic, cadmium pesticides, etc.
A list of toxic pollutants has been
proposed. Effluent standards for those
toxic pollutants listed will be published
later.
NEW SOURCE PERFORMANCE STANDARDS
Most new plants will be subject to
national standards for performance. EPA is
to publish a list of categories of sources
which must include 27 major types of indus-
tries and then issue regulations establish-
ing Federal standards of performance for
the new sources within such categories.
These standards are to assure that new sta-
tionary sources of water pollution are de-
signed, built, equipped, and operated to
minimize the discharge of pollutants. The
standards are to reflect the greatest degree
of effluent reduction which the Administra-
tor determines to be achievable through
application of the best available demon-
strated control technology, processes,
operating methods, or other alternatives.
"Best Available Demonstrated Technology" has
been described as those plant processes and
control technologies which, at the pilot
plant or semiworks level, have demonstrated
that both technologically and economically
they justify use in new production facili-
ties.
At the same time EPA promulgates new
performance standards, it is to provide
pretreatment standards for newly constructed
point sources discharging into public treat-
ment facilities.
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WATER QUALITY STANDARDS
The new Act does not ignore the concept
of water quality standards in 19.77 and 1983
achievements. Water quality standards which
were adopted and enforced under the old
Federal Water Pollution Control Act (FWPCA)
for interstate waters are continued in effect
and can be updated and the new ones are to
be established for intrastate water bodies
where not previously adopted by the States.
If water quality standards cannot be pro-
tected by the application of best practic-
able control technology for industries and
secondary treatment for municipal wastes
before 1977, then more stringent effluent
limitations are to be imposed which will
pro-tect water quality for public water
supplies, agricultural and industrial uses,
assure protection of a population of fish
and wildlife, and allow recreational activi-
ties.
EFFLUENT LIMITATIONS
The permit will contain one or more
sets of numerical limitations which must be
met by a date specified in an associated
compliance schedule. In general, the ef-
fluent limitations, with the exception of
pH, will be expressed in terms of total
weight (Ibs/day or kg/day). The effluent
limitations in the permit are described in
terms of daily average and daily maximum
values. The limitations expressed in the
permit are based on promulgated effluent
guidelines, interim guidance or water
quality standards if more stringent limits
are necessary to protect water quality. The
limitations or standards established by the
Agency are to be applied in a uniform manner
throughout the country. The standards are
minimum technological requirements to be
applied even though the receiving water may
not require that level of abatement to
achieve the desired water quality.
COMPLIANCE SCHEDULE
The compliance schedule will specify
when final effluent limits must be attained
and may also contain dates for achieving
certain plateaus such as development of
engineering reports, final plans, beginning
of construction, completion of construction
and the operation of facilities. Interim
dates and requirements are to be specified
in the permit as a means of monitoring
progress and minimizing slippage. Following
each interim date, the permitee must submit
a written notice of compliance or non-com-
pliance with the interim requirements. The
reports specified in the permit are very
important and should be submitted on time.
Failure to report, especially on construc-
tion progress or compliance, will result in
response from the Agency.
MONITORING AND REPORTING
The self-monitoring requirements con-
tained in the permit will be developed on an
individual basis with consideration given for
the type of treatment, the impact of the pro-
posed treatment facility on the receiving
water and the parameter to be measured. The
purpose of the monitoring program is to
establish that a treatment facility is con-
sistently meeting the effluent limitations
imposed in the permit. Data must be recorded
and retained on file by the permittee for at
least three years. The reporting frequency
of monitoring results will be specified in
the permit. A uniform reporting form has
been developed and will be provided to the
permittee. The self-monitoring may vary
from State to State as individual conditions
are developed to insure compliance with
State requirements.
The permits are issued for fixed terms.
The maximum duration of a permit will be
five years. The majority of permits have
been written for that period since it will
involve commitment to a long term abatement
program. Permits may be written for a
shorter period, however, e.g., the State
may require it or the facility may cease
operation.
STATE CERTIFICATION
After drafting, a permit is forwarded
to the appropriate States for certification.
The State has the right to add additional
requirements in monitoring, compliance, and
additional or more stringent effluent limit-
ations. The Agency, upon receipt of certi-
fication requirements, will place these in
the permit. Any challenge to any State
certification requirements must be through
State administrative procedures.
636
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STATUS OF THE PROGRAM AS OF JUNE 30, 1975
EPA and 24 States which were delegated
the authority to issue NPDES permits had,
as of June 30, 1975, issued 20,091 Indus-
trial permits; 16,664 Municipal permits;
1,548 Agricultural permits; and 1,988 Fede-
ral Facility permits making a total of
40,291 permits issued. Approximately 1600
EPA issued permits have been challenged
through Administrative Processes. Of these,
400 have been resolved through discussions
between interested parties, e.g., govern-
ment, industry, and public interest groups.
We expect very few appeals to proceed
through this process and into our courts.
A study to determine the total amount
of certain pollutants that will be removed
from our Nation's waters due to the imple-
mentation of P.L. 92-500 and the industrial
portion of the permit program resulted in
an estimated reduction of approximately 12
million pounds per day of BOD and 28 million
pounds per day of suspended solids.
The continuation of our effort will
now shift into compliance monitoring to
assure that the terms and conditions of the
permits are met and the goals of the Act
achieved.
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THE EPA PRETREAlMENT PROGRAM FOR INDUSTRIAL WASTES
Ernst p. Hall
U.S.E.P.A.
401 M Street, S.W.,(WH5b2) Washington, DC
20460
ABSTRACT
The Federal Water Pollution Control Act Amendments of 1972 (PL 92-500) directs the
promulgation of Federal standards for pretreatment of industrial waste waters which are
introaucted into a publicly owned treatment works. These standards will require pretreat-
ment to control pollutants which would interfere with a pass through a treatment works.
Enforcement will be primarily at the local level with a Federal overview and presence.
Pretreatment of industrial wastes
betore introduction into a publicaly
treatment works (POTW) has been discussed
by Mr. Sutfin at the second U.S./Japan
Conference. Since that presentation there
have been a number of refinements in our
thinking and approach to pretreatment.
This paper reflects the present status of
these refinements.
The Federal Water Pollution Control
Act Amendments of 1972, were designed by
Congress to achieve an important objective
- to "restore and maintain the chemical,
physical, and biological integrity of the
Nation's waters." Primary emphasis for
attainment of this goal is placed upon
technology based regulations. Existing
industrial point sources which discharge
into navigable waters must achieve
limitations based on Best Practicable
Control Technology Currently Available
(BPT) by July 1, 1977 and Best Available
Technology Economically Achievable (BAT)
by July 1, 1983 in accordance with
sections 301(b) and 304(b). New sources
must comply with New Source Performance
Standards (NSP) based on Best Available
Demonstrated Control Technology (BDT)
under section 306. Publicly owned
treatment works (POTW) must meet
"secondary treatment" by 1977 and best
practicable waste treatment technology by
1983 in accordance with sections 301(b),
304(dJ and 201 (g)(2)(A). Users of a POTW
also fall within the statutory scheme as
set out in section 301(b). Such sources
must comply with pretreatment standards
promulgated pursuant to section 307.
Limitations and standards applicable
to Direct dischargers are established for
categories and subcategories of point
sources. This same categorization is
applied to pretreatment and pretreatment
standards, generaly, will
for each category or
industrial point source
general pretreatment
existing sources (40 CFR
be established
subcategory of
discharge. A
regulation for
128) was adopted
some two years ago and is now undergoing
revision. I he revised regulation (40 CFR
4u3) is expected to provide a regulatory
basis for both existing and new sources.
The term "pretreatment" means the
application of physical, chemical and
biological processes to reduce the amount
of pollutants in or alter the nature of
the pollutant properties in a waste water
prior to discharging such waste water into
a publicly owned treatment works. I he
basic purpose of pretreatment is "to
prevent the discharge of any pollutant
through treatment works...which are
publicly owned, which pollutant interferes
with, passes through, or otherwise is
incompatible with such works." The intent
is to require treatment at the point of
discharge complementary to the treatment
performed by the POTW. Duplication of
638
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treatment is not the goal. Pretreatment
of pollutants which are not susceptible to
treatment in a POTW is absolutely critical
to the attainment of the overall objective
of the Act, both by protecting the POTW
from process upset or other interference,
and by preventing discharge of pollutants
which would pass through or otherwise be
incompatible with such works.
Pretreatment standards should allow
the maximum utilization of a POTW for the
treatment of industrial pollutants while
preventing the misuse of such works as a
pass-through device. The standards also
should protect the aquatic environment
from discharges of inadequately treated or
otherwise undesirable materials.
The primary technical strategy for
establishing pretreatment standards
consists of the following provisos: (1)
pretreatment standards should allow
materials to be discharged into a POlW
when such materials are similar, in all
material respects, to municipal sewage
which a "normal type" POTW is designed to
treat; (2) pretreatment standards should
prevent the discharge of materials of such
nature and quantity, including slug
discharges, that they would mechanically
or hydraulically impede the proper
functioning of a POlW; (3) pretreatment
standards should limit the discharge of
materials which, when released in
substantial concentrations or amounts,
reduce the biological effectiveness of the
POTW or achievement ot the POTW design
performance, but which are treated wnen
released in small or manageable amounts;
and (4) pretreatment standards should
require the removal, to the limits
dictated by technology, of other materials
which would pass through — untreated or
inadequately treated -- or otherwise be
incompatible with a normal type POTW.
In addition to these provisos, it
appears to be administratively necessary
and technically desirable to establish a
volume cutoff or limit below which most
materials may be discharged into a POTW,
while requiring pretreatment standards for
larger flows and more hazardous materials.
This is intended to be accomplished by
defining, for the purpose of the
regulation, a major contributing industry
is a discharger who either (a) has a flow
of 50,000 gallons per day, or (b) has a
flow equal to or greater than 5% of the
capacity of the POlW. Any discharger
meeting either of these requirements would
be subject to all pretreatment standards
while a discharger not classified as a
major contributing industry by this
criteria may not be required to meet
specific numerical pretreatment standards.
The specific determination is to be made
in each subpart and for some particular
subparts it may be desirable to alter or
change the definition of a major contri-
buting industry in order more properly to
apply pretreatment standards, particularly
where use of the volume cut-off would not
provide adequate protection to the
environment.
The first proviso is clear in its
application and materials meeting this
proviso should be allowed to be introduced
into a POTW without pretreatment. uther
applications ot these provisos will oe
discussed in the following paragraphs.
ihe control of influent pH is usually
adjusted adequately, particularly for
mildly acid wastes, by the alkalinity and
buffering capacity of normal municipal
waste waters. Additionally, if necessary,
treatment of pH can readily be
accomplished by chemical addition in a
POTW. However, highly acid wastes
characterized by materials having a pH
below five have the capability for
destroying the sewer pipes and sewage
treatment facility itself because of their
ability to attack metal, concrete and
mortar joints. One particularly adverse
reaction from the corrosion of acid wastes
is to destroy the integrety of in concrete
sewers, thereby allowing the infiltration
of water during a rainy season. For this
reason, very low pH wastes -- below a pH
of 5.0 -- are included as prohibited
wastes even though pH is generally
considered to be adequately treated in a
POTW.
Heat is defined in the Act as a
pollutant. In most cases, heat in fairly
substantial quantities can be discharged
into a municipal sewage system along with
waste water without causing an upset or
other difficulty in operating the POTW.
As a matter of fact, some heat,
particularly in cold weather, may prove to
be beneficial, and may accelerate the
effectiveness of the treatment process.
However, the normal POTW includes
biological treatment systems whose
performance can be affected adversely if
an excess of heat is found in tne
treatment plant itself. This point of
damage to biological activity is generally
639
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considered to be 40%C (|04%F). Hence,
some safeguard is needed to prevent an
excess of heat being discharged to the
treatment plant while still allowing
lesser amounts of heat to be discharged to
and dissipated in a POTW.
Slug discharges which cause an upset
in the treatment process and a subsequent
loss of treatment effectiveness are
undesirable both for environmental and
treatment plant operational reasons.
Defining a slug discharge in quantative
terms is difficult. It is commonly
recognized that the peak two hour flow
rate of normal municipal sewage is about
two times the ratio of the average daily
flow. This ratio holds for both hydraulic
loading and for oxygen demand (BOD)
loading. In order to establish a readily
definable discharge level at which an
industrial user may become liable for
causing a POTW upset, a slug discharge is
defined based on the normal maximum to
average ratio. However, the prohibited
waste section does not prohibit slug
discharges per se but only prohibits slug
discharges which cause a POTW upset.
Some materials are known to be treated
effectively in small concentrations in a
POTW but are not treated effectively
whenever the amount of such materials
exceeds the system's tolerance levels.
Regulation of these types of materials can
effectively allow the POTW to treat as
much of the pollutant as it reasonably
can, while preventing an excess of such
material from passing through untreated or
reducing the treatment effectiveness of
the PuTW. One such material currently
under review by the Agency is oi I and
grease of a mineral origin. The Agency is
considering establishing a general
limitation setting forth a specific
concentration as a pretreatment standard
for this particular parameter and a
request for public comment on this
proposal has been published in the Federal
Register (40FR17/62). This general
limitation would be implemented in each
subpart regulation rather than in a
general regulation. Other materials such
as ammonia, phenol and cyanide may be
considered for limitation in the same
manner as oil and grease of a mineral
origin.
Materials may at times be introduced
into a POTW in industrial waste waters for
which no treatment effectiveness data tor
a normal type POTW are available or for
wnich the known data indicate that
treatment effectiveness in the POTW is
highly variable or inadequate. In such
cases, it is obvious that the POTW cannot
be depended upon to effectively and
consistently remove the pollutant in
question. Under these conditions the
Agency expects to consider the application
of BPT or NSP limitations as the
pretreatment standard for these specific
materials. Materials which may be
included in this category would include
metals such as copper, nickel, chromium,
zinc and arsenic, and selected organic
materials.
Regulations under sections 301 and 306
generally have been established allowing
the discharge of a quantity or mass of
pollutant related to a unit of production
or other production vector. This basis
tor limitation has the considerable
advantage of reducing the discharge of the
amount of pollutants to a finite quantity
while encourging conservation in the use
of water and the reduction in the
generation of waste water within a
manufacturing process or operation. ihe
Agency believes that mass limitations Dest
fulfill the purposes of the Act. Mass
limitations based on similar
considerations appear to be the most sound
and effective mechanism for reducing the
amount of pollutants discharged to a POTW
whenever such pollutants would pass
through or otherwise be incompatible with
such works. I he Agency intends to use
this concept of limiting the mass of
pollutants discharged as the technical
basis tor the establishment of
pretreatment standards for many
pollutants.
The enforcement strategy, which the
Agency proposes to employ to achieve
pretreatment of industrial wastes
envisions tne application and enforcement
of these pretreatment standards by State
and local bodies including the POlW
receiving and treating the industrial
waste waters. It has been determined that
many State and local authorities are not
yet able to apply production related mass
limitations. Moreover, the Act does not
provide for pretreatment permits analogous
to the NPDES permits of section 402. For
this reason, the Agency, at this time,
expects to promulgate pretreatment
standards which are based on the discharge
of a specified quantity of pollutant
related to a production vector (e.g., Ibs
640
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of pollutant per ton of product), but
which are stated as a concentration of
pollutant in the discharge from a
particular industrial process or unit
operation. It is anticipated that the
rationale for the derivative of the
pollutant concentration standards will be
described in detail in the preamble to
each pretreatment standard for an
industrial subcategory. It is also
anticipated that restrictions and
constraints against water use and dilution
may be included when appropriate for each
subpart. It is intended that such
pretreatment standards be applied at the
individual process unit. Additionally an
alternate procedure will be made
available, as is appropriate for each
subpart, so that mass limitation may be
applied if both the industrial user and
POTW operator desire.
The Agency believes that the use of
pollutant concentrations as a pretreatment
standard for those materials which may
pass through untreated, or are otherwise
incompatible with a POTW is an interim
measure made necessary by the practical
constraints of enforcement. At some
future revision of these pretreatment
standards, the Agency anticipates that the
concentration numbers will be abandoned
and the mass limitation will become the
sole pretreatment standard.
All of the pretreatment standards
being considered are intended to apply to
users of a "normal type" of publicly owned
treatment works which is basically
designed and intended to treat domestic
waste waters to achieve the secondary
treatment standards as established in 40
CFR 133 and as required by the Act. The
secondary treatment standard requires that
a sewage treatment plant, in addition to
controlling pH and fecal coliform, reduce
the amount of biochemical oxygen demand
(BOD5) to 85 percent or less of the
influent value or to 30 mg/1 in the
discharge, whichever is the more
stringent. A similar restriction is
applied to suspended solids.
There are a number of sewage treatment
systems, which when properly designed and
operated, meet these requirements on a
consistent basis. These include the
activated sludge system and its
modifications, trickling filters, and
stabilization lagoons or oxidation ponds.
There are a number of activated sludge
system modifications which incorporate
variations on the amount of sludge
recirculation, the amount of air or oxygen
supplied to the reaction chambers, the use
of pre- and post-chlorination, and the use
of sludge digestion, sludge combustion, or
land filling as mechanisms tor disposal of
the sludge generated. The retention time
of sewage in such systems generally is
short; it is nominally considered to be 6
hours while retention times as short as 3
or 4 hours are not uncommon. Trickling
filters are often used where the input
waste water is relatively constant and
where savings in power and operator
attention are needed. Stabilization
lagoons or oxidation ponds can be used
where the necessary land area is available
and where climatic and soil conditions are
such that the long retention times
required by such lagoons or ponds can be
achieved. "A normal type" POTW should not
have regular, substantial chemical
additive needs for the purpose of removing
materials other than BOD and TSS.
Existing publicly owned treatment
works rarely include processes such as
physical chemical treatment (which is only
now becoming a full scale reality in a few
areas) or special variants or combinations
of biological treatment units that are
primarily intended to address the special
needs of industrial waste water pollutants
rather than domestic waste or water
quality requirements.
Variations from the promulgated
pretreatment standards may be necessary in
certain circumstances to compensate for
factors not adequately considered in
establishing these standards. This has
been recognized in the establishment of
other industrial effluent limitations and
is equally applicable to pretreatment
standards. Two kinds of variants appear
to be appropriate depending on the
particular circumstance.
In the preparation of the development
document for each point source category
all of the information which the Agency
could collect concermnq processes and
procedures related to the industry
subcategory was collected and analyzed.
It is possible, however, that certain
facts did not become available to the
Agency and could not be employed in
decisions related to the pollutants which
may be discharged from a particular
industry operation or would be related to
the treatability or impact which such
pollutants might have upon a POTW. For
641
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this reason, a variance clause is provided
which would allow the establishment of a
pretreatment standard, other than that
promulgated in the applicable subpart, in
those cases where it could be shown that
factors related to the industry category
fundamentally different from those
considered in the development document
exist and that these factors require the
establishment of a different pretreatment
standard.
An analogous situation may occur with
respect to factors related to the publicly
owned treatment works. A variance clause
is provided to allow a different
pretreatment standard to be established
for those cases where a publicly owned
treatment works can be shown to be
substantially different from the normal
type of publicly owned treatment works on
which pretreatment standards are being
based. Some of these types of
installations are known to exist or are in
the planning or design stage. However, at
this time it is difficult to establish a
separate regulation which would make an
allowance for different factors in such
publicly owned treatment works.
Although both EPA and the States will
play major roles in enforcing pretreatment
requirements, the Agency believes that
local governments will probably have to
play the most important role in any
successful enforcement program. Local
governments operate the POTWs, which are a
vital part of the overall effort to clean
up the nation's waterways, and so are
sensitive to and directly affected by the
pretreatment program. They are closest to
the problem and are already frequently
involved in related areas such as
regulation of sewers and collection of
user charges. Moreover, a local role in
pretreatment enforcement is consistent
with the partnership of Federal and local
effort found in the construction grants
program and other parts of the Act.
As those with the most immediate stake
in the success of the pretreatment
program, both in terms of protection of
the proper functioning of the POTW and in
terms of protection of the local
environment, local governments will be the
first line of defense. One way they may
exercise tneir crucial role is by means of
a local ordinance - a preferred route, and
one specifically preserved by the Act. It
is expected that each manager of a
treatment works would provide for such
standards." Local governments may also use
the citizen suit provisions of section
505. Section 505 is available because
local governments are "persons" as defined
in the Act "having an interest which is or
may be adversely affected". The citizen
suit provisions allow suit to enforce a
Federal or State pretreatment standard
either against the industrial user of the
POiW or against the State or Federal
government (for failure to take proper
action). The Agency anticipates that
pretreatment guidance published pursuant
to section 304(fj will be of assistance to
local governments in carrying out their
responsiblities.
The Agency believes that parallel
efforts of all three levels of government
will be needed for a successful
pretreatment program. To the maximum
extent possible, EPA will encourage and
assist State and local enforcement action.
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MUNICIPAL SEWER UTILITY FINANCING UNDER PL 92-500*
C. C. Taylor, Program Analyst
Environmental Protection Agency
1421 Peachtree Street, N. E.
Atlanta, Georgia 30309
ABSTRACT
The Water Pollution Control Act Amendments of 1972 imposed significant financial
requirements upon grantees under the Federal Construction Grants Program administered by
the Environmental Protection Agency. This paper discusses the legislative history and
implementation experience of these grant conditions which are commonly referred to as the
user charge and industrial cost recovery requirements.
All recipients of Federal construction grants must demonstrate legal., financial, and
managerial capability to complete construction and provide adequate operation and main-
tenance during the life of the facility. Grantees must also develop and implement user
charge systems whereby all users pay the costs of operation, maintenance and replacement
in proportion to their use of the treatment facility. Such charge systems must also in-
clude provisions for reimbursement of Federal construction costs allocable to industrial
users.
The Environmental Protection Agency's implementation of these statutory requirements
is impacting the institutional pattern of municipal sewer utility management. More
adequate operation and maintenance is assured, and greater equitability in the distribu-
tion of costs is being attained.
Public response to the imposition of user charges has been reasonably receptive.
Compliance with industrial cost recovery requirements continues to generate controversy,
particularly with respect to applicability, cost allocation, and accountability.
INTRODUCTION
During the long and somewhat torturous
legislative history of The Water Pollution
Control Act Amendments of 1972, the Honor-
able Robert E. Jones of the U. S. House of
Representatives characterized this legis-
lation for his collegues as follows: "Mr.
Chairman, this is an enormously complex
bill, and necessarily so, because our water
environment has become enormously compli-
cated because of the urbanization and in-
dustrialization of our society. Our legis-
lation must take into account the myriad
of the water needs issue" (1).**
Subsequent to enactment, the act has
been called many things, ranging from the
most significant legislation of the decade
to the most comprehensive, the most com-
plex and the most confusing legislation
ever enacted at any time or place in the
history of man. Whether or not either of
these latter characterizations are justi-
fied, PL 92-500 is, without doubt, compre-
hensive in scope. Many of its provisions
are complex, and implementation of some of
*Paper prepared for presentation at Fourth
U. S,/Japan Conference on Sewage Treat-
ment Technology, Washington, D. C.,
October 28-29,1975.
**Numbers in parentheses designate refer-
ences on page 6.
643
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the provisions have been accompanied by some
confusion and controversy. This includes
implementation of significant provisions
relating to cost-sharing and cost alloca-
tion. The emphasis of this paper is fo-
cused upon these financial aspects of the
subject legislation.
BACKGROUND OF PL 92-500
In the spring of 1967, a joint Commit-
tee of the American Public Works Associa-
tion, the American Society of Civil
Engineers, and the Water Pollution Control
Federation reviewed the most significant
problems of the broad area of administra-
tive, legislative, and financial issues of
municipal water and sewer service. As a
result of the initial review, the Commit-
tee decided to focus its activities upon
the most urgent area, namely wastewater
financing and charges (2). This was indic-
ative of the general conclusion that most
of our municipalities were not adequately
prepared, at that time, to assume and
manage the rapidly escalating financial
and administrative responsibilities of
sewer service.
A leading management consultant firm,
working under contract with EPA Region
VIII, found this general situation little
changed by 1972 (3). Our nation is, of
course, geographically large and widely
diverse with respect to political structur-
ing. Obviously, this broad generalization
did not apply to all municipalities indivi-
dually. However, as a general rule, munic-
ipal sewer utilities were operated largely
as a public service financed by annual
appropriations from general revenues.
Generally, cost accounting systems, and
their attendant legal and financial insti-
tutions were not adequate for efficient
operation as financially self-sustaining
public utilities. It was in this atmos-
phere that The Congress deliberated legis-
lation which culminated in PL 92-500.
During this legislative process, many
complex and controversial issues were dis-
cussed and debated, after which some were
resolved and some apparently compromised.
These deliberations are reflected in the
'Committee and conference report (1).
Of the significant issues debated, two
pertain directly to our subject of finan-
cial management. First, Congress fully
recognized that the costs of attaining
the desired levels of clean water were
going to be large - we might even say
enormous.
The most recent "Needs Survey" cost
estimate for the backlog of municipal
facilities which are normally funded under
the EPA Construction Grant Program - that
is, only treatment facilities and attendant
interceptors and outfalls - was at the
level of approximately 50 billions of
dollars (4). We have known for some time
that attainment of the desired levels of
pollution control was going to be costly,
and Congress was fully aware of this as
they legislated this act.
Second, the committee reports reflect
that Congress also was fully aware of the
basic necessity of getting maximum return
for each dollar of this enormous investment
and that this could be done only with im-
proved and adequate operation and mainte-
nance. Why go to the expense of building
these facilities if they were not going to
be operated and maintained in such a way
that they would do the job for which they
were designed?
As a result of these deliberations,
the Congress reached some basic decisions.
First, the level of Federal cost sharing
for the construction costs of the large
backlog of needed publicly-owned municipal
facilities would be raised to 75 percent.
Second, it would be necessary to find
some way to move our municipal sewer sys-
tems to a sounder financial basis whereby
they could become more financially self-
sufficient. This should be done by pro-
moting a shift of the sewer service
function from a public service basis to a
public utility basis whereby;
a. Wastewater treatment and control
service would be paid for by the
users of that service.
b. The users would pay these costs on
the basis of the extent of their
use of the system. In this way,
there would be an economic and
financial incentive to reduce
waste discharge or at least hold
it to an amount for which each
user would be willing to pay.
Third, after extended, and apparently
heated debate about the Federal funding of'
644
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9. PROPOSED SEWERAGE SERVICE AREA OF EACH MUNICIPALITIES
FOR RESPECTIVE PHASES
(1) Priority and its concept
The priority for sewage works of each municipalities is determined by taking
into account the following:
a) Magnitude of effects on water quality
The order of the magnitudes of cost-benefit ratio (volume of removal of
pollutant loads per unit cost) of the sewage works required to remove loads for the
purpose of attaining the environmental standards at each stations in 1975.
b) Magnitude of necessity of improvement of the environment
The order of population densities (as census of 1970) reckoned as overcrowded
index showing the urban environmental aggravation.
Based on the above two factors the conditions of sewage works under ways,
conservation of water sources, aggravation of environment and other various factors
are put together to determine the priority of sewage works as follows.
i) Areas to launch immediately into the sewage works
Hiroshima City (local sewage works, Ohta River Service Area, Seno River
Service Area), Koyo Town, Hiroshima City (Gion), Yasufuruichi Town.
ii) Areas to launch as early as possible
Itsukaichi Town, Hiroshima City (Kabe), Sato Town, Fuchu Town, Funakoshi
Town, Kaita Town, Senogawa Town, Yano Town.
iii) Areas to launch early
Aki Town, Hiroshima City (Numata), Saka Town.
(2) Proposed sewerage service areas for respective phases
The service area by the sewerage required for purpose of attaining the
environmental water quality standards for 1975 and 1980 is shown in Table 19.
And for 1985 and 1990, sewerage service area will be covered to achieve
pollutant load reductions more than specified in the guidelines for the purpose of
improving amenity.
Table 19 Area of Coverage for the Planned Years
Year
1975
1980
1985
1990
1990 service area
(ha)
16,596 (ha )
Service area by year
(ha)
4,256
7,931
13,665
16,596
Ratio of service area
(%)
26
48
82
100
373
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10. EFFECTS OF THE PROGRAM ON WATER QUALITY PROTECTION
It is insufficient that the protection of the quality of public waterways
presupposes at once consideration to the utilization of waters by men. We should
take account into the conservation of minimum environmental standards necessary
for fellow living creatures.
As regards the Ohta and Seno River Basin, the water quality should be restored
to a point of allowing swimming as Hiroshima was once called as "the City of
Waters".
Based on this principle, the program will be evaluated not only to improve the
environment, consequently to prevent water pollution, to regain clean waters, and to
conserve water sources, but also to improve the water quality to the level shown in
Table 20 which will be high enough even if the environmental water quality
standards are tightened in the future.
Table 20 Water Qualities at Each Stations for Respective Phases
_^^^ Water qualities
Standard stations ^~~""— - — _^_^
Ohta River,
1. Intake point of Hesaka
water supply
2 Ohta canal,
' Asahi Bridge
o Temma River,
' Showa Great Bridge
4 Original Ohta River,
Funairi Bridge
j Motoyasu River,
Minami Great Bridge
g Kyobashi River,
Miyuki Bridge
7 Enko River,
Niho Bridge
o Seno River,
Hinoura Bridge
Existing water
quality
(BOD ppm)
1.6
(A)
4.5
(B)
1.3
(A)
1.2
(A)
0.6
(A)
1.7
(A)
10.1
(C)
3.2
(B)
Classification
Left alone
Improved by
implementation
Left alone
Improved by
implementation
Left alone
Improved by
implementation
Left alone
Improved by
implementation
Left alone
Improved by
implementation
Left alone
Improved by
implem entation
Left alone
Improved by
implemen tation
Left alone
Improved by
implementation
Predicted water quality (BOD ppm)
1975
2.9
2.0
5.7
3.0
1.7
1.7<
1.5
1.5<
0.6
0.6<
1.7
1.7<
12.0
8.0
4.9
4.9<
1980
4.4
2.0
7.3
3.0
2.1
2.0
1.9
1.9<
0.6
0.6<
1.7
1.7<
14.8
5.0
8.2
3.0
1985
6.0
0.6
9.0
0.6
2.7
0.6
2.4
0.6
0.8
0.8
1.8
1.6
18.2
0.6
10.3
0.8
1990
7.6
0.6
10.9
0.6
3.3
0.6
2.9
0.6
0.8
0.8
1.9
1.7
21.7
0.6
13.0
0.9
Note: Letters parenthesized denote types of waterways according to environmental water quality standards.
374
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11. FUTURE STUDIES
In the preparation of the program, some assumptions are made for want of data
concerning water pollution.
From now on, various data, especially those concerning water qualities should
be collected in order to provide for every-five-year previous and the following
studies should be pushed forward to refine the plans for promoting the sewage
works reasonably.
(1) Improvement of the existing combined sewer system
The effects of wet weather conditions on the water quality of the combined
sewer system should be studies in order to provide measures for sewage treatment
and modification into separate sewer system and to determine their implementation
schedule.
(2) Development of water pollution mechanisms in the tidal waterways
The tidal waterways in the lower reaches of the Ohta River (Hiroshima City)
are experiencing some 3 m of tidal range. As pollutant loads running into the tidal
waterways have different effects on water qualities depending on the tidal current
and the change of water level, the pollution mechanisms should be developed along
with analysis of measurements at stations with reference to the water quality
standards.
(3) Examination of pollution in sea
Water quality conservation in the Bay of Hiroshima should also be studied with
reference to the environmental water quality standards.
12. IMPLEMENTATION OF SEWAGE WORKS
According to the studies, the Ohta River comprehensive sewage works was
launched in 1972 and a part of the alignment of trunk was completed in 1974.
From this year on, the construction of sewage treatment plant will be started.
Along with the Program, Hiroshima City local sewage works is also in progress.
375
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Fourth US/JAPAN Conference
on
Sewage Treatment Technology
Paper No. 6
FURTHER DISCUSSIONS OF THE FEDERAL WATER
POLLUTION CONTROL ACT OF 1972
October 29, 1975
Washington, D. C.
Ministry of Construction
Japanese Government
376 -
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FUTURE DISCUSSIONS ON FEDERAL WATER POLLUTION CONTROL ACT
AMENDMENTS OF 1972
T. Kubo, Japan Sewage Works Agency
1. INTRODUCTION > 378
2. THE GOALS AND POLICY OF THE ACT 378
3. MUNICIPAL SECONDARY TREATMENT 379
4. FINANCING 381
5. OCEAN OUTFALLS AND OCEAN DUMPING 381
5.1 Ocean Outfalls 381
5.2 Ocean Dumping 382
6. PRETREATMENT 384
7. USER CHARGE 386
8. INDUSTRIAL COST RECOVERY 391
577
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1. INTRODUCTION
At the Second U.S./Japan Conference on Sewage Treatment Technology,
December 1 ~ 6, 1972, in Washington, D.C., presentation in relation to the Federal
Water Pollution Control Act amendment of 1972 was made by U.S. side to the
Japanese Delegation, when it was just beginning to implement the Act. During the
Second Conference the Japanese Delegates recognized that the great amount of
discussions had been made in the House and Senate on the Act itself and the
national policy for environmental pollution, and the passage of the Act was really a
historical event in the field of water pollution control in the United States. And the
Japanese Delegates then paid attention on its thoroughness and comprehensiveness,
and paid respects to the nation's ambitious goals which were set against water
pollution control.
At the Third Conference, February 12 ~ 16, 1974, in Tokyo, Mr. Charles H.
Sutfin of U.S. EPA Headquarters, Washington, D.C., described that since 1972 U.S.
EPA had worked very hard, learned much and in doing so significant progress had
been made toward full implementation of the Act. As we can see it in the
Proceedings of the Third Conference that the state viewpoint and municipal
viewpoint presented during the Third Conference made it clear that the various state
governments and local municipalities had no single viewpoint on the merits of the
1972 Act. During the Third Conference various arguments and criticizms on the Act
were raised by both the U.S. and Japanese side and also made some comments on it
particularly from viewpoint of water quality standard, effluent standard, grants for
construction of treatment works, research and related programs. It seems that most
of state civil servants think that the Act has produced serious flaws in the field of
water pollution control and has been wrongly implemented, for instance, Section
101 (b) of the Act states that it is the policy of the Congress to recognize, preserve
and protect the primary responsibilities and rights of States to prevent, but actually
the federal role is all pervasive and conformity to the federal mold is much more
mandatory than statutory language would require, and the goals indicating
recreational use water quality in all streams by 1983 and zero discharge of pollutants
by 1985 are unrealistic, particularly the schedules. We realize that there must be
difficult problems for full implementation of the Act, and nevertheless we would
like to pay our respects to EPA's ambitious goals in the field of environmental
pollution control through full implementation of the Act. Today, I would like to
discuss with you on several points of the Act, but particularly to emphasize the
specific area of pretreatment, user charge system and industrial cost recovery under
the Act.
2. THE GOALS AND POLICY OF THE ACT
The goals and policy of the Act are declared in the Section 101 (a) of the Act,
to wit;
(1) It is the national goal that the discharge of pollutants into the navigable waters
be eliminated by 1985.
(2) It is the national goal that wherever attainable, an interium goal of water
quality which provides for the protection and propagation of fish, shellfish and
378
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wildlife and provides for recreation in and on the water be achieved by July 1,
1983.
(3) It is the national policy that the discharge of toxic pollutants in toxic amounts
be prohibited.
(4) It is the national policy that Federal financial assistance be provided to
construct publicly owned waste treatment works.
(5) It is the national policy that areawide waste treatment management planning
processes be developed and implemented to assure adequate control of sources
of pollutants in each State.
(6) It is the national policy that a major research and demonstration effort be
made to develop technology necessary to eliminate the discharge of pollutants
into the navigable waters, waters of contiguous zone, and the oceans.
It can be deeply recognized for us that the public in the U.S.A. has become
more aware of water pollution and the climate of public opinion has remarkably
changed to support the clean-up effort in the activities of Federal, State and
municipal levels. -Of course, without the public's support, it will be impossible to do
the job of water pollution control. The passage of the 1972 Act is very significant
that the goals are indicated clearly for the nation's commitment to clear water and
the Act is certainly a commendable effort on the part of the Federal Government to
upgrade and/or preserve the chemical, physical and biological integrity of the
nation's waters, and the public is encouraged by the Federal Government's
recognition of the problems of water pollution and its determination to deal with
these problems.
It is understandable in general that the concept of setting water quality
standards for the nation's waters and the concept of specifying minimum treatment
levels regardless of stream requirements are sound and agreeable. The continuing
planning process mandated by Section 303 (e) of the Act is a also sound and
necessary to take comprehensive countermeasure for pollution prevention. This kind
of planning can lead to take a more effective view at the overall water quality needs
in each river basin and also lead to keep a much more coordinated control program
than has been the case. It seems that State Governments and municipalities would
express their attitude to keep close coordination with federal government to
implement the 1972 Act.
Under these circumstances it seems that the goals and policy of the Act should
not be altered and all governments in each level and the public would try to attain
the goals, even if there must be some change in the schedules to attain the goals.
3. MUNICIPAL SECONDARY TREATMENT
Section 301 (b) (1) (c) of the Act says in effect that by July 1, 1977 publicly
owned treatment works shall produce either a secondary treated effluent, or an
effluent subject to advanced waste treatment if this is required to meet stream
standards. It seems to me that the requirement that all municipalities provided a
minimum of secondary treatment by 1977 may be difficult in some instances
because of the time needed to plan, design, and construct facilities and also shortage
379 -
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of budgetary action.
According to the Secondary Treatment Information on secondary treatment
pursuant to Section 304 (d) (1) of the Act, secondary treatment may not be capable
of meeting the percentage removal requirements during wet weather in treatment
works which receive flows from combined sewers. For such works decision should
be made on case by case basis as to whether any attainable percentage removal level
should be. In any case it will need huge amount of fund to meet requirements in
these cases. Section 202 (a) provides that the amount of any Federal grant for
publicly owned waste treatment plant made under the Act shall be 75 per centum of
the cost of construction. But actually the level of funding as evidenced by past
experiences would fall far short of the need. On the contrary national pollutant
discharge elimination system as provided with Section 402 of the Act will require to
apply and insure compliance with Section 301, 302, 306, 307 and 403. Moreover in
the NPDE system discharge from storm overflow on combined sewers to public on
case by case basis.
When the permit program is coupled with the grant program for publicly
owned treatment works as established under Title II of the Act, a real dilemma does
result. Actually it would appear to us that the federal government is telling state and
local municipality on the one hand through permit system to construct rapidly the
needed publicly owned treatment works; and on the other hand telling same state
and municipality through the grant program that they are entitled to receive 75%
federal funding, but it will not be forthcoming in many cases in time to meet the
1977 deadline. These two hands make confusing. It is extremely necessary to resolve
this problem so that federal government can proceed harmoniously to construct the
necessary works and also to maintain and operate the works satisfactorily. The
congress is always hurry to take action and determine the deadline in disregard of
possible materialization, but the engineers should consider the attainable and
reasonable deadline. What date is it reasonable to attain the goal of 1977? There
must be many difficulties to cope with the time limitation of the Act for small
communities. Judging from my knowledge I am still obliged to acknowledge that it
will be too short to attain not only the deadline of 1977 but also the ambitious
national goals. It is easy to propose ammendments that will establish reasonable
compliance schedules of the Act. But in the other hand we should pay attention that
frequent ammendments might lose confidence for the national policy in the public.
We have same problems in Japan. In our Japanese practice when the
environmental quality standard is fixed in some river basins, it will be usual to
determine the deadline to attain the standard in each river basin according to the
classification of environmental quality standard, and the deadline itself will not be
so rigid, for instance, it will be indicated in such a way that 'within five years or as
soon as possible within ten years' either by industrial waste treatment or publicly
owned treatment plant. But it is still >in many cases impossible to keep the deadline
because of various difficulties such as shortage of budget available, lack of
well-trained engineers etc. In addition to this in most of Japanese large cities the
combined sewer system has been taken and in many cases storm-overflows do exist
on sewers.
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In these cases it needs huge amount of money to meet the requirements which
will be decided on the case by case basis.
4. FINANCING
In Japan a significant problem related to the water program involves acute
future financing of municipal waste treatment works. It seems to me that the
situation on this matter in U.S. will be same as in Japan. Expanded eligibilities, more
stringent abatement requirements, and increased construction costs have combined
to raise the demand for federal grants far beyond the levels contemplated when the
1972 Act was enacted.
EPA's 1973 needs survey conducted under Section 516 (b) (2) of the Act
identified a potential demand of 45 billion dollar from the Federal Government to
fund project estimated to cost 60 billion dollar. A recent needs survey of 1974
shows that the cost of construction of all needed publicly owned treatment works in
all of the States is 115 billion dollar. But when the costs for treatment and/or
control of storm waters are included, the total costs will come to 350 billion which
will be a huge sum of money to take a budgetary measure.
It seems that U.S. EPA is looking at such alternative financing strategies as
differences in funding, in matching formulas, and in eligibility requirement to meet
the deadline. I would like to follow such a financing strategies in the U.S. EPA's
policy, because in Japan the Third Five-Year Plan (1971 ~ 1975) for Sewage Works
will be completed by being invested amounting 2,600 billion yen, but it is expected
to have another Fourth Five-Year Plan (1976 ~ 1980) for Sewage Works carried out.
The Ministry of Construction has made it clear that the total cost estimates for
construction of publicly owned wastewater treatment plants and collecting sewers
will need another 16,000 billion yen to attain the environmental quality standard in
each river basin in Japan. Japanese Environmental Agency is responsible to fix
environmental quality standard, and has already completed to fix it in about 300
river basins. We have continued arguments in relation to financing on sewage works
and how to meet with needs and requirements.
Recently Ministry of Construction has requested to Ministry of Finance that
the Fourth Five-Year Plan for Sewage Works should be appropriated 11,000 billion
yen for the budget. Even if such program is proceeded completely the target dates
will be postponed for some years, but Ministry of Finance has still showed
unwillingness for such a huge budgetary request.
Under these circumstances we shall have to look for alternative financing
strategies to attain environmental quality standard.
5. OCEAN OUTFALL AND OCEAN DUMPING
5.1 OCEAN OUTFALL
The U.S. EPA published information on secondary treatment under Section
304 (d) (1) of the 1972 Act. It described the minimum level of effluent quality
attainable by secondary treatment in terms of the parameters BOD, SS, PH and B.
Coli. It requires, in general, 85% removal or 30 mg/C of BOD and SS whichever is
more stringent. All publicly owned treatment works must provide treatment at least
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to this level by July 1977. We realize the 1972 Act and its legislative history clearly
shows that the regulation is principally to be based on the capabilities of secondary
treatment technology and not ambient water quality effects.
In the case of more stringent limitation, including those necessary to meet
water quality standard required to implement any applicable water quality standard
established pursuant to the 1972 Act, it shall be obliged to provide more advanced
waste treatment technology. In the sense of necessity to meet water quality standard
it will be necessary to take in account of capabilities of various kinds of treatment
and decide the effluent limitation. Particularly it seems that biological oxygen
demand is not a problem in ocean waters because there exists an abundant supply of
oxygen available for degradation of municipal wastes.
Is there any possibility to reconsider the effluent limitations and their
enforcement to take in account of water quality standard in each case particularly in
the case of ocean outfall. For such treatment works the decision must be made on a
case by case basis as to whether any attainable percentage removal level can be
defined.
5.2 OCEAN DUMPING
We understand that it is the policy of the U.S. EPA to regulate the dumping of
all types of materials into ocean waters and to prevent or to regulate strictly the
dumping or other discharge into ocean waters of any material in quantities which
would adversely affect human health, welfare, amenities, or the marine environment,
ecolo'gical potentialities, or plankton, fish, shellfish, wildlife, shorelines or beaches.
It seems that the Section 403 (c) of the 1972 Act requires that application for
permits for the dumping or other discharge of any materials into the marine
environment be evaluated on the basis of the impact of the materials on the marine
environment and marine ecosystems, on the present and potential uses of the ocean,
and on the economic and social factors involved.
The regulation of ocean dumping may vary according to the types of waste
materials as follows;
(1) The dumping of some types of waste materials into the marine environment is
prohibited and will not be approved by U.S. EPA under any circumstances.
Such prohibited waste materials are identified as follows;
i) High-level radioactive wastes
ii) Materials produced for radiological, chemical or biological warfare.
iii) Materials insufficiently described in terms of their physical, chemical or
biological properties to permit evaluation of their impact on marine
ecosystems.
(2) The disposal of some types of waste materials into the marine environment is
strictly regulated to prevent or minimize known or adverse effects on the
aquatic ecosystem or human health and welfare. These materials and limiting
concentrations and conditions upon the disposal of these materials are given as
follows in the criteria; and these materials will be considered as trace
contaminants when they are present in sewage sludge.
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i) Organohalogen compounds
ii) Mercury and its compound: Solid state: Less than 0.75 mg/kg
Liquid state: Less than 1.5 mg/kg
iii) Cadmium and its compounds; Solid state: Less than 0.6 mg/kg
Liquid state: Less than 3.0 mg/kg
iv) Total oil
Do not produce visible surface sheen in an undistributed water sample
when added at a rate of one part waste material to 100 parts of water.
(3) The disposal of some types of waste materials in subject to less strict regulation
and permission because of the minimal adverse environmental effects to be
anticipated.
i) Waste materials containing none of the materials mentioned above (1), (2)
with limiting permissible concentration may be regarded as none-toxic in
the marine environment.
ii) Solid waste
Solid waste of natural minerals or materials compatible with the marine
environment may be generally approved for ocean disposal.
iii) Disposal of dredged materials
(4) Materials requiring special care are as follows;
Arsenic Lead Copper Zinc Selenium
Vanadium Beryllium Chromium Nickel
in these cases it is obliged that the applicant can demonstrate that the material
proposed for disposal meets the limiting permissible concentration of total
pollutants considering both the pollutants in the waste material itself and the
total mixing zone available for initial dilution and dispersion.
Under these regulation for ocean dumping of waste materials I assume that in
U.S.A. suggestion must be made so that the general permit could be used to allow
the dumping of municipal sludge, because I am told that there were many
experiences for dumping of municipal sludge into marine environment without any
impact for the cited environment.
Ocean dumping in Japan is prohibited as a rule except for some cases when
dumping is permitted by the regulation relating to the Marine Pollution Prevention
Act 1970 and policy of Japanese Government on this matter is going in the same
line as in U.S.A. At the moment ocean dumping of municipal sludge in Japan is
almost impossible because of strong opposition from fishermen, but some members
of the scientific community including fishery science are contended that
biodegradable organic matter such as municipal sludge with some nutrients will not
adversely effect on marine environment or plankton or fish. It is extremely
necessary to conduct large-scale research demonstration in this field, but actually we
have now in Japan strong opposition even for such experimental research works.
I am told that a permit for dumping of materials into the ocean as part of
research into the impact of materials on the marine environment may be issued by
U.S. EPA Administrator when he determines the scientific merit of the proposed
project outweighs the potential damage that may occur from the dumping under the
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following conditions;
i) The applicant provides to the Administrator a detailed statement of the
proposed project, including an assessment of the probable environmental
impact carrying out the project.
ii) There is public notice and opportunity for public hearing.
iii) Research permit will be issued for no longer than 18 months, but may be
renewed after review by the U.S. EPA Administrator.
The research permits of ocean dumping may be good idea to solve our
problems in Japan demonstrating the actual examples. We shall be much obliged if
you will show us some examples of research permits in which research works on
ocean dumping of municipal sludge have been carried out.
6. PRETREATMENT
Pursuant to Section 307 (b) of the Federal Water Pollution Control Act
Ammendments of 1972 the pretreatment standards for introduction of pollutants
into publicly owned treatment works can be described in terms of the following
pollutants;
(1) Pollutants which are determined not to be susceptible
(2) Pollutants which would interfere with the operation and maintenance of such
treatment works
This means that pretreatment standards are designed to achieve both to prevent the
discharge of pollutants which pass through such works inadequately treated —
incompatible — and to protect the operation of publicly owned treatment works —
prohibited wastes —.
I realized that the definitions of compatible pollutant, incompatible pollutant,
joint treatment works, and major contributing industry are very important to
understand practical implementation of the 1972 Act. It should be noticed that
compatible pollutant will be the pollutant identified in the National Pollutant
Discharge Elimination System (NPDES) permit if the publicly owned treatment
works does remove such pollutants to a substantial degree (about 80% removal)
including COD, TOC, P, N, Fats, Oil and Grease. It should be noticed also that under
the NPDES all point source including publicly owned treatment works to must
obtain a permit for the discharge of wastewater to the navigable waters of the
United States, but permits will not be required for industrial wastewater discharging
into public sewers, and the effluent limitations for a pollutant in the discharge from
a publicly owned treatment works will be individually determined by the regulating
agency being based upon Secondary Treatment Information, Toxic Effluent
Standards, Water Quality Standard whichever the most stringent limitation.
Under these circumstances it is very important to have strong and clear
pretreatment policy considerations.. Judging from the definition of incompatible
pollutants it may be recognized that incompatible pollutants will be materials to
inhibit biological activities and to give accute or chronic effects to aquatic life. I do
agree that generally speaking the incompatible pollutants in amounts greater than
would be permitted if the user discharged directly into navigable waters should be
confined into the in-plant site, and accordingly the pretreatment standards for
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incompatible pollutants are the same as the standards for direct discharge into
navigable waters. Pretreatment is required for incompatible pollutants to the levels
of best practicable control technology currently available as defined for industry
categories under Section 304 (b) of the 1972 Act.
Incompatible pollutants including toxic effluent will not be designed to protect
sewer systems as a general principle, but to protect aquatic life in the navigable
waters concerned from both acute and chronic impacts, but we have to pay
attention that such incompatible pollutants as heavy metals may accumulate in the
sludge generated by the publicly owned treatment works.
Recently we have been doing experimental works of sludge application on farm
land, and in doing so we have realized that farmers are so nervous to apply sewage
sludge on their farm land due to heavy metal accumulation in the soil. From these
points of view it is recognized that we should review pretreatment standards and
should keep such materials as heavy metals in the sludge to such a degree that sludge
may be applied safely to farm land.
It seems that the Pretreatment Standard is deficient in that it fails to impose
specific numerical limitations on the discharge of pollutants of prohibited waste and
also incompatible pollutants. Of course it can be realized that the necessary degree
of prohibited wastes and incompatible pollutants in each treatment works depends
on the concentration of pollutant in the treatment works itself rather than the
concentration of each user's effluent. It will, however, be quite required that a
national pretreatment standards should be workable and enforceable and for that
purpose it must be prescribe the permissible concentrations of particular pollutants
of the user's effluents. Otherwise the user will not know what step he must take to
comply with the pretreatment standards.
It is my understanding that joint treatment of industrial and municipal
wastewaters in the same plant is generally a desired practice, because there are some
advantages which are in the terms of increased flow which can result in reduced ratio
of peak to average flows, savings in capital and operation and maintenance expenses
due to the economics of large-scale treatment facilities and better use of manpower
and land etc., and joint treatment of domestic sewage and adequately pretreated
industrial wastewaters is encouraged where it is the economical choise including
social costs.
Under stringent pollution control policy being taken in Japan, there is a
tendency that municipalities will be unwilling to receive industrial wastewaters into
public sewers due to difficult job relating to inspection and monitoring, but
industries will be willing to discharge their wastewaters into public sewers.
The fact that an industry chooses to use a public sewer system rather than
discharging his wastewater directly into the navigable waters should not involve
getting away from penalty, and the industry concerned, of course, should provide
his own pretreatment plant provided with currently best practicable control
technology and also should pay the appropriate money to the municipality
concerned according to polluters pay principle, PPP
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7. USER CHARGE
Section 204 (b) (1) of the 1972 Act prohibits Federal grant assistance to a
municipality unless it has adopted a proportionate user charge system to defray
costs associated with operating and maintaining a facility including replacement. In
the Federal guidline relating to user charges for operation and maintenance of
publicly owned treatment works, it is written that Section (b) (1) of the Act
provides that after March 1, 1973 Federal grant applicants shall be awarded grants
applicants only after the Regional Administrator has determined that the applicant
has adopted or will adopt a system of charges to assure that each recipient of waste
treatment services will pay its proportionate share of the cost of operation and
maintenance including replacement. The intent of the Act with respect to user
charges is to distribute the cost of operation and maintenance of publicly owned
treatment works to the pollutant source and to promote self sufficiency of
treatment works with respect to operation and maintenance costs.
It seems that the problem is compounded because of an opinion of the
Comptroller Genera] which prohibits U.S. EPA from funding new projects in areas
where municipalities are utilizing ad valorem tax systems to finance wastewater
treatment operation and maintenance charges.
During the Third Conference there was a discussion presented by Metropolitan
Sanitary District of Greater Chicago, and I quote: "Under our present system, we
collect revenue from an ad valorem property tax together with an industrial
surcharge when the discharge of an industry exceeds 3,650,000 gallons within a
12-month period. This method of funding has proven successful and the merits of
changing this proven method are dubious. Another problem is presented in attempts
to measure the discharge of each domestic user to achieve a fair allocation of the
cost of treatment. The Metropolitan District of Greater Chicago plus 116 other
municipalities. It is a practical impossibility to monitor the discharge of every
domestic user in the Chicago metropolitan area. One suggested alternative is to
correlate water consumption with discharge to the sewers and base the user charge
on the volume of water consumption.
This might be feasible in many of the 116 municipalities outside the City of
Chicago where water is metered but within Chicago there are about 350,000
nonmetered users. These users, mostly residential, are charged a flat rate for water.
Under a direct user charge, about 350,000 water meters would have to be installed
within the City of Chicago at a cost of approximately 60,000,000 dollars. The cost
of reading these additional 350,000 meters is estimated to be somewhere around
3,000,000.00 dollars a year.
The contemplated user charge assumes that the sole function of a district is the
collection and treatment of waste. The Metropolitan Sanitary District, however, is
also charged by statute with the additional duties of flood control, maintenance of
waterways, and the abatement of the pollution of waters from which any
municipality might receive its water supply. This, of course, means the protection of
Lake Michigan. These additional responsibilities would have to be funded by the ad
valorem tax, so that even if a user charge is invoked, it would still be necessary to
levy the ad valorem tax.
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There would also exist the problem of enforcing the user charge if a user
become delinquent. When you consider that the Metropolitan Sanitary District
serves 5.5 million people and 11,000 industries in the metropolitan Chicago area, it
is easy to see that we would be forced to spend a great deal of time in collecting or
attempting to collect deliquent charges. Yet, this would be only a small part of the
total cost of administration of user charges. The major expense would be in the
routine billing and collection from literally hundreds of thousands of users. Now —
in our present tax system, we succeed in collecting 89% of the tax levy. This money
is forwarded to us by the county collector automatically and routinely without cost.
The difference here speaks for itself.
How then the user charge benefit the taxpayer? I suppose it is possible that a
system can be devised where the cost for each user will be more proportionate than
it is now. Bear in mind, however, that a proportionate share under the user charge
will probably mean a greater cost to the average homeowner than he is now paying
in taxes, when you consider the administration and collection costs, and a collection
experience that cannot be expected to approach 89%.
The Metropolitan Sanitary District is not taking a hostile position to the
Federal requirements. We are simply advocating that our present method of
financing by an ad valorem property tax coupled with an industrial surcharge meets
the intent of the EPA standard for user charge."
It seems that the presentation by Metropolitan sanitary District of Greater
Chicago does tell us whole story for user charge system in the case of cities with
proud history of sewage works operation of their own. And it can not be helped to
say that in these cases it would be reasonable to give such cities discretion utilize
modified user charge system to pay their share of operation and maintenance costs.
The basic principle of user charge system in Japan which is suggested by
Ministry of Construction will be described as follows;
(1) Construction cost of facilities for sewerage and sewage treatment shall be
covered by public expenses including grant, public loan, local tax and so on.
(2) Operation and maintenance cost of facilities excluding cost of replacement
shall be paid by the revenue from the user charge.
(3) User charge should be divided into two classes.
i) Domestic user charge
ii) Industrial user charge
Domestic user charge shall cover only operation and maintenance cost
excluding replacement of facilities and be decided by quantity discharged into
sewer.
Industrial user charge shall cover not only operation and maintenance cost but
also cost of replacement by reservation of depreciation account. That portion
should be recovered in accordance with so called Polluters Pay Principle and be
decided by quantity and quality requirement discharged into sewer.
(4) User charge system on a graduated scale shall be taken in order to economize
water consumption and so quantity discount to large volume users will not be
acceptable.
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(5) Water consumption with discharge to the sewer should be correlated by water
meter and water consumption by well from ground water with discharged to
the sewer shall be estimated on the basis of pump capacity and its running
hours.
Philosophy of these basic principle is: pollution should be stopped and
controlled at the source. One of the most effective methods of reducing the
pollution load into the sewer caused by industrial effluents is to make a user charge
which is based on a sliding scale in accordance with their quantity and quality. In
this way an incentive can be given to the trader to reduce his discharge of waste
from his factory and in doing so to pay less user charge, by re-using water, by
making minor modifications in manufacturing processes, by recovering by-products
or by some means. Some remarkable results have been achieved in this way with
profit to the trader, and with great advantage to sewage treatment operation, and
with considerable resulting contribution to the national economy including water
resources. Recently experiences of sewage works operation in Osaka City, Japan,
have shown the remarkable reduction of industrial effluents into the public sewer by
employing the suggested user charge in terms of industrial effluents. With regard to
water resources investigation the Ministry of Construction published that by 1985
the 1970 output of water conservation works in Japan will be needed to be about
1.5 times as a nation-wide. The major water deficiency areas are in large
metropolitan areas such as Tokyo, Osaka, Nagoya, Kobe, Fukuoka, Sendai etc., and
even for the deficiency areas the high costs of building dam and transmission may
link that the transfer of water from remote dam site has no obvious advantage from
view points of costs.
The future water demand estimated by the Ministry of Construction is shown
in the Table 7.1. Firm long-term forecast are not be available, but there seems to be
obvious limit to the growth in demand for water from water undertakers, both to
meet increased domestic consumption consequent upon rising social living standards
and to serve the growing demands of industry. It has now been realized that the fast
increasing consumption of water, both domestic and industrial, will make imperative
a much greater reuse of water and also economical usage in both domestic and
industrial purposes in terms of consumption in nearly all over Japan.
Under these circumstances it appears that the user charge system on a
graduated scale will be more effective in such a way that the users including
domestic and industrial consumers may try to save water consumption to pay less
user charge, and in doing so an incentive can be given to dischargers also.
Each house is provided with its own water meter in almost every municipality
in Japan and water consumption with sewage discharge into the sewer can be
correlated. In this connection there is no difficulty to employ user charge system for
us. Recently the charge system in .terms of water and sewage has been revised in
Tokyo Metropolitan Government as shown in Table 7.2..The basic principle of this
revision is going in the same line as mentioned above.
In this cases of water consumption with discharge of same amount, say
monthly consumption, 10m3, 20m3, 50m3, 100m3, 1,000m3, calculation of
water and sewage charge in each case under Tokyo Metropolitan revision is shown in
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Table 7.1 Future Water Demand Estimation
(0.1 billion cub. m. per annum)
Hokkaido
Tohoku
Kanto
Hokuriku
Tokai
Kinki
Chugoku
Shikoku
Kyushu
Total
1970
Domestic
3.6
9.1
34.0
2.0
10.6
21.2
5.5
2.6
7.1
95.7
Industrial
9.6
16.1
33.0
10.2
38.7
28.4
16.1
9.0
13.5
174.6
Agricultural
49.7
129.5
83.3
28.4
46.4
44.5
48.8
23.1
69.9
523.6
Total
62.9
154.7
150.3
40.6
95.7
94.1
70.4
34.7
90.5
793.9
1985
Domestic
8.6
17.5
69.0
4.6
27.1
39.7
12.6
6.2
21.3
206.6
Industrial
32.4
46.5
65.8
20.6
64.2
46.3
30.8
22.8
41.4
370.8
Agricultural
56.9
143.8
87.5
28.9
52.8
42.8
52.2
26.4
94.2
585.5
Total
97.9
207.8
222.3
54.1
144.1
128.8
95.6
55.4
156.9
1,162.9
Table 7.2 List of Water Charge and Sewer User Charge in Tokyo Metropolitan Gove.nment
List of Water Charge (Yen)
Old
Basic charge
100
100
120
120
140
500
500
12,000
Range
(n/)
0~8
9~18
19~30
31~50
51 -100
101~200
201 ~ 1,000
1, 000 ~ over
Specific
charge due
to quantity
0
20
25
28
45
55
68 v
75
New
Basic charge
300
300
400
400
500
2,400
17,000
Range
(m3)
0~10
11 ~20
21-30
31-100
101 —200
201-1,000
1, 000 ~ over
Specific
charge due
to quantity
0
60
75
90
120
150
180
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List of Water Charge (Yen)
Old
Basic charge
80
Range
(m3)
0-8
9 over
Specific
charge due
to quantity
0
10
New
Basic charge
100
100
300
1,200
2,950
7,450
23,900
56,450
Range
(m3)
0~10
11—20
21~30
51 ~ 100
101 ~200
201-500
501-1,000
1,000 over
Specific
charge due
to quantity
0
20
30
35
45
55
55
75
Table 7.3 Water and Sewage Charge as shown in Yen/cub, m. in Tokyo
Water Charge
10m3
20m3
50m3
100 m3
1,000 m3
Old
14.00
18.50
23.60
34.50
63.71
New
30.00
45.00
71.00
80.50
142.05
Sewer User Charge
Old
10.00
10.00
10.00
10.00
10.00
New
10.00
15.00
28.00
40.50
80.25
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Table 7.3.
It seems to me that the sewer user charge system can be expanded to apply to
pollution charge system in overall water pollution control. Levying charges on those
who discharge wastewater into public water body in proportion to the quantity and
the nature of the wastewater. By and large the charge mechanism provides just such
an incentive. Instead of having water as a natural resource of infinite capacity, we
find ourselves in a position where water is a limited resource which urgently needs to
be managed. The preparedness of industries to reduce their waste effluents was
strongly stimulated by the fact that the annual charge levied for financing water
quality management is directly related to the volume and the nature of the effluent.
This made it economically attractive for any industry to try and find a solution to
the problem of how to limit the amount of waste to be discharged.
Pollution should be reduced in the point where the costs of doing so are
covered by the benefits from the reduction of pollution. What is required, ideally, is
some incentive to polluters to reduce pollution up to the point where the costs to
them of further pollution abatement would be greater than damage done by the
pollution. This is why the ideal means of avoiding excessive pollution at least in
principle, is to make the pollution pay a charge corresponding to the damage done
by his pollution.
This principle is attractive and justified, not only does it associate the cause
with the consequence, but it has also become clear from practice that having to pay
a charge makes an industry much more pollution-minded. This circumstance,
combined with a strong permit policy, may lead to a considerable reduction of the
pollution and may often change a potential pollutor into a supporter of water
quality management.
Management of water resources should take into account social, economic,
scientific and technical aspects and the sewer user charge system would be a key to
water management by expanding it to pollution charge system.
8. INDUSTRIAL COST RECOVERY
Pursuant to Section 204 (b) (3) of the 1972 Act, "The grantee shall retain an
amount of the revenues derived from the payment of costs by industrial users of
waste treatment services, to the extent costs are attributable to the Federal share of
eligible project costs provided pursuant to this title as determined by the
Administrator, equal to (A) the amount of the non-Federal cost of such project paid
by the grantee plus (B) the amount, determined in accordance with regulations
promulgated by the Administrator, necessary for future expansion and
reconstruction of the project, except that such retained amount shall not exceed
50% of such revenues from such project. All Revenues from such project not
retained by the grantee shall be deposited by the Administrator in the treasury as
miscellaneous receipts. That portion of the revenues retained by the grantee
attributable to clause (B) of the first sentence of this paragraph together with any
interest thereon shall be used solely for the purpose of future expansion and
reconstruction of the project."
It seems that a grantee must elect to compute industrial cost recovery amounts
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annually on projects completed within an established accounting period. Such fund
also must be segregated in special accounts and accounting procedures must be
established to permit audit at any time during the recovery period.
It will be possible to determine what percentage of the capacity of the sewage
treatment plant is attributable to any industry, but if there are many major
contributing industries which discharge their wastewater into sewage treatment
plant, such a determination can be • an immense even if not an impossible task. In
these cases cataloging of industries for the purpose of cost proportioning would
require the sewage works authority concerned to keep record on great amount, and
the authority would have to know when there is a change in ownership, when one
goes out of business, or when a new one comes, when one changes its manufacturing
processes or raw materials to be treated in its factory, continuously revising each
business' contribution.
I would like to have informations on this matter and good examples in practice
which has been carried out satisfactorily with the requirements of Section 204 (b)
(3) of 1972 Act.
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Fourth US/JAPAN Conference
on
Sewage Treatment Technology
Paper No. 7
WET WEATHER FLOW AND COMBINED SEWER
OVERFLOW ABATEMENT TECHNOLOGY
October 29, 1975
Washington, D. C.
Ministry of Construction
Japanese Government
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WET WEATHER FLOW AND COMBINED SEWER OVERFLOW ABATEMENT
TECHNOLOGY
K. Saito and M. Kashiwaya, PWRI, Ministry of Construction
1. Sewer Served Area and Status Qua in the Sewer Collection System in Japan . .395
2. Investigation on the Storm and Combined Sewer Overflow in Japan . 396
3. Quality of Combined Sewage and Urban Storm Water . . 393
4. A Proposal of Storage Tank , . ...-399
394
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WET WEATHER FLOW AND COMBINED SEWER OVERFLOW
ABATEMENT TECHNOLOGY
1. SEWER SERVED AREA AND STATUS QUO IN THE SEWER COLLECTION
SYSTEM IN JAPAN
In 1974, 426 municipalities were undertaking sewage works in Japan. In 1975,
60 municipalities are launching sewage works.
In 1974, an area of 2,080 km2 was sewered, accounting for 25.5% of the urban
area in Japan. The population served by sewers are estimated to be 38 million.
In 1972, Ministry of Construction made a survey on the sewer collection sys-
tems. 316 municipalities responded to our inquiries. The results of the survey are
shown in Table 1. It is found that 104 municipalities employed the combined sewer
systems, while 96 cities used the separate sewer systems. There were 81 cities where
the sewer systems were mainly of the combined type and partly of the separate type.
Most of these cities applied the combined sewer systems to the urban area and the
separate type to the suburbs.
In 35 cities, major portion of their service area had separate sewers with the
remaining portion served by combined sewers. This type of sewer systems are classi-
fied into two; one in which separate sewers are used in steep areas, while combined
sewers in plane areas, and another in which the newly developed residential zones in
the suburbs use separate sewer systems while the most old urbanized areas are re-
maining unsewered. In the areas covered by the combined sewer systems, there live
26.31 million or 70% of sewer served population.
Table 1 shows a comparison between Japan and the United States as to the
combined sewer systems.
In Japan, the cities employing the separate sewer systems have been increasing
as combined sewer systems was criticized for its combined sewer overflow problems.
Ministry of Construction also has been recommending the separate sewer systems for
the purpose of water pollution control.
If the unsewered cities will be arranged with separate sewer systems, Japan's
sewer systems will reach almost the same level as in the United States.
- 395 -
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2. INVESTIGATION ON THE STORM AND COMBINED SEWER OVERFLOW
IN JAPAN
Since 1967, Public Works Research Institute, Ministry of Construction has
made investigations on the storm and combined sewer overflows.
The data concerning rainfalls, storm water and water quality for the 1867~69
period were collected from five cities ~ Tokyo, Nagoya, Toyohashi, Kyoto and Gifu.
The data collected were aimed at the preparation of design manual for new sewerage
plans and the evaluation of the existing combined sewer systems. The areas investi-
gated were each different in population and land use from others.
The survey also included the examination of applicability of the rational me-
thod, measurement of inlet time and time of concentration, investigation of runoff
coefficient, actual quality of sewage in the wet-weather conditions, and change in
the rainfall runoff attendant on urbanization.
Although the surveys were completed in 1969, from 1970 till now the observa-
tion of rainfalls and rainfall runoff has been carried out in the catchment area of
the Yabatagawa, Tokyo. In the guidelines for the sewerage which were established in
1972 by Japan Sewage Works Association, it is recommended that the unsewered
areas should be served by separate sewer systems, because combined sewer system is
liable to cause storm water overflow problems leading to water pollution. But, the
guideline leaves how to improve the existing combined sewer system over for the
future study.
For this reason, a survey on the improvement of the combined sewer system or
its alternatives has been conducted since 1973. So far, the survey has tackled the
problems incidental to the overflow from the combined sewer, flow rate, water
quality and characteristics of combined sewage and storm water discharge, assess-
ment of alternatives proposed, and preparation of a conceptual plan for a storm
water storage tank with the Yabatagawa catchment (Tokyo) taken as a model.
In 1975, engineers from Ministry of Construction, local governments and
Japan Sewage Works Agency rallied to establish "Committee on Combined Sewer
Overflow Problems." The purposes of the Committee are to let its members investi-
gate the sewer systems in their respective cities, to have them exchange the informa-
tions obtained with each other, and thereupon to study how to improve the com-
bined sewer systems in the respective cities. The Central Government is in a position
to appraise the achievements of each city, while the Committee, which appripriates
the outlays for the collecting of data necessary for the Central Government to persue
the problems, is going to undertake research activities from 1975 till 1980.
The results of the investigation will be used not only as data for the Govern-
ment's long-term projection, but also for the planning of each city's combined sewer
improvement programs and preparation of the design manual for sewage system.
On the other hand, the Tokyo Metropolitan Government has made various in-
vestigations along the Yabatagawa and the Momozonogawa. The themes for the
investigations include the examination of infiltration loss in the urban area, applica-
bility of RRL method, development of modified RRL method, examination of the
storm water drainage system, preparation of pollutant discharge model, etc.
- 396 -
-------
In 1975, Tokyo Metropolitan Government relocated the observation station to
Ogu District for continued survey. The District is a plain, and storm water is drained
by pumping. The sewerage always carries a large amount of stagnant water. Hence,
the results of the survey may become different from those in the Yatabegawa and
the Momozonogawa.
Osaka Municipal Government planned a combined sewage (storm water) sedi-
mentation tank on the occasion of the repairs of the Nakanoshima Pump Station
located at the center of the city. The tank will be composed of six basins each meas-
uring 3.5 m in width, 20.2 m in length and 5.2 m in height. Two out of six were
completed in 1975. Osaka Municipal Government will use these tanks for the meas-
urement of the volume and quality of influent and examination of the feasibility of
the similar tanks which will be planned and constructed from now on.
The results of survey, such as conducted by local governments will be also sub-
mitted to the Committee on Combined Sewer Overflow Problems.
Water pollution problems due to storm water discharge in the urbanized area is
not solely developed by combined sewer overflow.
In the old cities, dry-weather flow has been increased with the progress of ur-
banization, which has resulted in a shortage of sewer capacity. Namely, in dry weath-
er conditions, raw sewage is liable to be delivered to the receiving waters without
treatment or even when the rainfalls are not so severe, overflows have happened.
Consideration to the alternatives to solve the combined sewer overflow pro-
blems in these cities should also cover the measures to make up the shortage of sewer
capacity. Sewer separation will become one of effective measures, except in those
heavily build-up areas which have high population density. In most of oldest cities,
the conversion of the existing combined sewer systems into the separate one is al-
most impossible as various restrictions are present, and alternatives may have to be
taken up. There are many alternatives proposed, and their practicability should be
examined from various aspects.
The results of this kind of surveys conducted by U.S. EPA are very informative
to us.
In the separate sewer systems on the other hand, urban storm water itself pre-
sents a serious pollution problem. Also, excessive infiltration into sanitary sewer
systems is concerned about since it results in overloading to sewage treatment facili-
ties. In the existing separate sewer systems, storm water flow mainly in gutters,
natural water courses, etc. If the urbanization advances in the future, storm water
runoff will overrun the capacity of these facilities. It will be therefore necessary to
drastically reconstruct the storm drainage facilities, install a basin in the city in order
to pool storm water temporarily. In some case porous pavement and the like which
decrease the rainfall runoff coefficient should be incorporated.
- 397 -
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3. QUALITY OF COMBINED SEWAGE AND URBAN STORM WATER
Public Works Research Institute has investigated the quality of combined sew-
age in Tokyo, Nagoya and Kyoto.
Table 2 shows test locations. The results of surveys are shown in Table 3 ~ 5.
According to a U.S. EPA survey report* the quality of combined sewer
overflows are that of raw sewage or its half. In Japan, the tendency is almost the
same. It is interesting to note that the quality is nearly the same for all that the way
of living and rainfall conditions are quite different between the two countries (Table
6).
In the Yabatagawa District in Tokyo, the "first flush" is found noticeable at a
rainfall of 10 mm/hr to 20 mm/hr, particularly when heavy downpours are seen in
the beginning (Fig. 1). At 3 to 5 mm/hr of rainfall, it is not found precisely (Fig. 2).
In the case of high-intensity rainfall, dilution phenomenon is noticed (Fig. 3).
If two consecutive rainfalls are present, "first flush" occurs in second railfall,
even when their interval is short especially the second one is heavy (Fig. 3, Fig. 4).
What is noticeable in the first flush includes BOD, SS, etc., and nutrients, total-coli.
are rarely seen.
In 1975, surveys on combined sewage have being conducted in 11 largest cities;
Sapporo, Tokyo, Kawasaki, Yokohama, Toyohashi, Nagoya, Kyoto, Osaka,
Hiroshima, Kitakyushyu, Fukuoka. As regards the storm water discharge into the
separate sewer system, surveys were carried out in Gifu, Kobe and Yamagata for the
purpose of contrasting them with the combined sewage. Table 7 shows the test loca-
tions and the results in Table 8 ~ 10.
Storm water discharges were found seriously polluted, and ocassionally these
quality were similar to raw sewage. Such Heavy metals as Zn, Pb, were also included
considerably in storm water discharge (Fig. 5). The mean value was poorer than
the secondary effluent, showing little difference from the survey results in U.S.A.
(Table 11). In Japan, gutters and natural small water courses have been used for the
purpose of drainage where the separate sewer systems is applied. In dry weather con-
ditions, pollutants deposite in them and are scoured away with rain water. This has
been the major cause of the pollution of storm water from the separate sewer system.
In 1975, the survey on urban storm water has been continued in Kobe.
The total rainfalls in Japan are 1,500 mm/year to 2,000 mm/year, and typhoons
visit, bringing about heavy downpours. But generally, Japan's largest cities have a
high population density and use large quantities of water. Accordingly, the annual
BOD and SS loading of the effluent from the sewage treatment plant are much more
than those in the combined sewer overflow which is directly discharge into the re-
ceiving waters.
Namely, the effluent from the sewage treatment plant is always imposing higher
loading on the receiving waters. Table 12 is the results of an estimate with a down
town in Tokyo taken as a model.
It is clear from Table 12 that BOD loading of the combined sewer overflow
* F.J. Condon "Storm and Combined Sewer Abatement Technology in the
U.S.A. - An Overview -" EPA, Feb., 1974.
398
-------
accounts for no more than 20%.
Most of nutrients are contained in sew ige treatment plant effluents.
4. A PROPOSAL OF STORAGE TANK
There are a lot of proposals for overcoming the combined sewer overflow pro-
blems.
One such example is a storage tank. It is believed to have the following advan-
tages.
1) The structure is simple and easy to operate.
2) The conventional sewage treatment technology is applicable.
3) Stage-wise construction is possible, and takes effect soon as local modification
of sewage treatment facilities will do for the purpose.
4) Capacity of the existing sewer can be increased.
5) Wide fluctuation of storm water flow can be controlled and equalized.
Particular emphasis may be placed on the last merit since Japan often is hit by
heavy downpours.
Pulbic Works Research Institute estimated the effects of the combined sewage
storage tank with the Yabatagawa District, Tokyo as a model.
The District lies northwest of Tokyo, and covers an area of 541 ha with the
combined dewer systems. The result of estimation are as follows; in this district, the
calculated BOD and SS loadings are as shown in Fig. 6 namely, the removal rate of
BOD and SS loadings consequent upon the discharge of storm water is only 22% and
28%, respectively.
By installing three tanks, 27,000 m3, 54,000 m3 and 81,000 m3, 40% to 70%
of the annual storm water discharge of 440 mm can be storaged. The storaged storm
water is sent to the sewage treatment facilities in dry weather and then discharged
into the receiving waters after secondary treatment. The results of this study indi-
cates, the removals of BOD and SS loadings are from 60 to 70% and 70 to 80%
respectively as shown in Fig. 7 Another benefit is the reduction of annual overflow
frequency which is reduced to 42, 16 and 11 as against the theretofore 78.
Even if the district were served by separate sewer system, it will still deliver
pollutants at an annual rate of 118 tons in BOD and 391 tons in SS as the storm
water discharge is polluted.
The amount is tantamount to the installation of a storage tank with a capacity
of 58,000 m3
Unfortunately, however, it is hardly possible to find out an open space allowing
the construction of such a large facility.
It is therefore concluded that the storage tank should be constructed beneath
public facilities such as park, parking lot, open space necessary at the time of earth-
quake etc. In this way, precious space can be used effectively.
399 -
-------
Table 1 Relative Use of Combined Sewers
Municipalities
Combined sewer
Combined and partialy separate
Separate and partialy combined
Separate sewer
Total
Area (km2)
Combined sewer
Separate sewer
Total
Population
Combined sewer
Separate sewer
Total
Japan
104
81
35
96
316
1,526
552
2,078
2,631
1,166
3,797
%
33
26
11
30
73
27
69
31
31
U.S.A.
1,329
12,000
36,236
89,534
125,770
%
10
90
29
71
400 -
-------
Table 2 Test Location (Combined Sewer)
City
Tokyo
Kyoto
Nagoya
Nagoya
Test location
Yabatagawa
Chubu-daiichi
Tamitsu
Chitose-nambu
Drainage area
(ha)
540.6
67.8
51.4
81.2
Population
120,000
17,000
9,900
12,300
Land use
Residential,
semi-industry
Residential
Residential
Semi-industry, harbar
commercial
- 401 -
-------
Table 3 Characteristics of Combined Sewage (1) (Yabatagawa, Tokyo)
Unit: mg/C
\s
BOD
S-BOD
T-S
ss
VTS
T-N*
T-P
July 31, 1972
Sample
No.
61
30
30
61
30
16
16
Max.
353.0
63.0
886.0
686.0
274.0
17.3
2.88
Mean
94.2
29.0
569.0
340.5
142.7
11.3
1.79
Min.
38.5
15.1
305.0
94.0
51.0
7.3
1.07
September 9, 1972
Sample
No.
56
28
28
56
28
15
15
Max.
158.0
55.8
535.0
214.0
101.0
14.7
2.78
Mean
104.6
37.1
462.9
140.9
66.2
14.2
2.51
Min.
69.4
25.6
324.0
55.0
42.0
13.2
2.15
October 6, 1972
Sample
No.
44
22
22
44
22
11
11
Max.
240.0
66.1
1,076.0
716.0
262.0
33.8
5.92
Mean
102.3
33.6
531.0
251.3
136.7
14.6
2.78
Min.
30.0
18.5
353.0
92.0
42.0
10.0
1.74
July 21, 1973
Sample
No.
35
11
11
35
11
6
6
Max.
317.4
94.3
1,025.0
788.0
463.0
36.1
7.20
Mean
121.7
65.3
548.1
154.9
233.3
24.7
4.56
Min.
62.3
49.8
294.0
32.0
124.0
14.4
2.50
\
BOD
S-BOD
T-S
SS
VTS
T-N*
T-P
July 29, 1973
Sample
No.
70
34
19
70
19
10
10
Max.
147.0
448
475.0
375.0
318.0
29.4
3.10
Mean
89.0
18.3
196.9
86.6
113.3
9.8
1.17
Min.
31.3
10.2
185.0
11.0
56.0
10.1
0.80
August 1, 1973
Sample
No.
60
24
24
60
24
12
12
Max.
246.3
73.8
1,133.0
1,020.0
604.0
11.7
1.90
Mean
88.6
19.4
341.4
221.2
171.3
4.3
0.54
Min.
16.6
10.8
131.0
16.0
58.0
3.7
0.50
August 4, 1973
Sample
No.
83
28
30
83
30
-
-
Max.
177.7
63.4
680.0
475.0
318.0
-
-
Mean
70.1
8.8
142.7
113.8
64.4
_
-
Min.
19.8
10.2
134.0
14.0
59.0
-
-
August 10, 1973
Sample
No.
35
11
11
35
11
_
-
Max.
244.5
88.2
1,092.0
857.0
641.0
—
-
Mean
99.5
36.7
323.5
182.4
174.3
—
-
Min.
19.6
23.5
197.0
21.0
93.0
-
-
\
BOD
S-BOD
T-S
SS
VTS
T-N*
T-P
August 24, 1973
Sample
No.
44
13
13
44
7
-
-
Max.
613.4
238.4
1,935.0
1,768.0
984.0
-
-
Mean
93.0
21.0
192.1
152.2
419.5
-
-
Min.
25.4
8.6
139.0
39.0
104.0
-
-
August 25, 1973
Sample
No.
26
9
9
26
9
-
-
Max.
126.8
52.5
388.0
243.0
234.0
-
-
Mean
101.1
10.5
105.8
118.0
183.9
-
-
Min.
63.2
13.7
185.0
64.0
88.0
-
-
November 10, 1973
Sample
No.
121
121
121
121
121
61
61
Max.
367.5
37.9
819.0
680.0
378.0
26.7
3.14
Mean
45.5
9.3
249.4
162.9
89.7
6.8
0.54
Min.
11.6
3.9
93.0
14.0
31.0
2.4
0.18
Summary
Mean
91.8
35.3
257.5
175.0
163.2
12.2
1.97
Range
11.6~613.4
3.9-238.4
93.0 ~ 1,935.0
11.0-1,768.0
31.0-984.0
1.9-36.1
0.18-7.20
: Kjeldahl
-------
Table 4 Characteristics of Combined Sewage (2)
^\\^
\^
BOD
ss
vss
3 Aug., 67
Sample
No.
29
29
-
Max.
1,176.0
393.0
-
Mean
88.1
214.0
-
Min.
55.3
9.0
-
22 Aug., 67
Sample
No.
23
23
23
Max.
108.8
523.0
106.0
Mean
49.35
298.0
63.0
Min.
22.0
96.0
12.0
31 Aug., 67
Sample
No.
27
27
27
Max.
219.5
525.0
185.0
Mean
71.37
331.0
77.8
Min.
19.2
92.0
20.0
Summary
Mean
69.0
283.0
70.4
Range
19.2-1,176.0
9.0-525.0
12.0-185.0
-------
Table 5 Characteristics of Combined Sewage (3)
(Tamitsu & Chitose-nambu, Nagoya)
"^^^_
^\
Tamitsu
BOD
ss
Chitose-nambu
BOD
SS
19 July., 67
Sample
No.
40
40
Max.
296.6
4,310.3
Mean
72.6
1,228.8
Min.
4.2
5.8
22 Aug., 67 (1)
Sample
No.
8
8
Max.
59.7
372.5
Mean
84.7
333.6
Min.
5.0
3.2
22 Aug., 67 (2)
Sample
No.
14
14
Max.
80.6
1,289.1
Mean
63.9
455.5
Min.
3.5
4.7
13 Sep. ,67(1)
Sample
No.
19
19
21
21
Max.
51.3
879.2
70.0
514.5
Mean
44.0
411.9
32.3
254.5
Min.
5.7
13.8
7.3
13.3
13 Sep., 67 (2)
Sample
No.
12
12
Max.
16.8
38.5
Mean
55.9
141.2
Min.
7.1
16.8
Summary
Mean
64.2
514.2
32.3
254.5
Range
3.5 ~ 296.6
3.2 ~ 4,310.3
7.3-70.0
13.3~514.5
-------
Table 6 Comparison of Quality (Strength) of Combined Wastewater Overflows
Type of wastewater and city
Raw Sanitary Flow
Primary Effluent
Secondary Effluent
Combined Sewer Overflows
Atlanta, Ga.
Berkeley, Calif.
Brooklyn, N.Y.
Bucyrus, Ohio
Cincinnati, Ohio
Des Moines, Iowa
Detroit, Michigan
Kenosha, Wisconsin
Milwaukee, Wisconsin
Racine, Wisconsin
Sacramento, Calif.
San Francisco, Calif.
Washington, D.C.
Yabatagawa, Tokyo
Chubu-daiichi, Kyoto
Tamitsu, Nagoya
Chitose-nambu, Nagoya*
BOD5
mg/£
Ave.
200
135
25
100
60
180
120
200
115
153
129
55
119
165
49
71
92
70
64
32
COD
mg/£
Ave.
500
330
55
—
200
-
400
250
-
115
464
177
—
238
155
382
—
-
-
-
SS
mg/e
Ave.
200
80
15
—
100
1,051
470
1,200
295
274
458
244
434
125
68
622
175
283
514
255
Total
coliform
MPN/lOOme
5x 107
2xl07
1 x 103
1 x 107
-
-
1 x 107
-
-
-
2x 106
-
-
5 xlO6
3x 106
3 x 106
—
-
-
-
* 1 storm
- 405
-------
Table 7 Test Location
City
Gifu
Kobe
Yamagata
Test location
Shimizugawa
Hanakuma
Midorimachi
Drainage area
(ha)
106.4
17.2
13.7
Population
24,500
2,700
1,000
Land use
Commercial
Residential,
commercial, office
Residential,
commercial, office
406
-------
Table 8 Quality of Urban Stormwater
(Hanakuma, Kobe)
(1)
BOD
S-BOD
SS
VSS
T-N*
T-P
Grease**
Total
MPN
3 Sep., 73
Sample
No.
24
14
24
14
14
14
14
14
Max.
980.0
57.6
2,561.0
1,360.0
65.8
1.15
538.3
250,000
Mean
99.4
13.2
756.8
196.0
15.8
0.73
31.7
Min.
13.0
8.5
24.0
13.0
2.3
0.36
1.0
3,100
27 Oct., 73
Sample
No.
51
27
51
27
27
27
27
27
Max.
136.0
43.0
196.0
83.0
10.7
2.06
28.7
77,000
Mean
31.0
11.0
76.4
35.6
3.8
0.67
6.3
Min.
9.5
2.7
6.3
10.0
1.4
0.38
0.1
80
21 Jan., 74
Sample
No.
52
27
52
27
27
27
27
27
Max.
743.0
70.0
2,130.0
959.0
71.0
2.96
138.0
500,000
Mean
104.6
11.9
475.0
179.0
12.3
0.68
22.7
Min.
15.0
5.0
13.4
1.0
1.5
0.32
1.0
2
*:Kjehldahl
Soxhlet method
BOD
S-BOD
SS
VSS
T-N*
T-P
Greass**
Total
MPN
1 Sept., 74
Sample
No.
39
20
39
20
20
20
20
20
Max.
136
6.4
417
86
11.1
1.08
12.4
61,000
Mean
17.7
3.5
97.8
22.0
1.96
0.22
3.8
-
Min.
5.2
2.2
27.2
5.6
0.9
0.12
1.6
400
1 Oct., 74
Sample
No.
70
35
70
35
35
35
35
35
Max.
85.6
13.1
381
111
7.4
0.49
9.7
35,000
Mean
7.4
2.5
78.6
17.7
1.27
0.14
2.40
-
Min.
1.83
1.46
9.4
2.8
0.62
0.05
0.2
1,300
4 Feb., 75
Sample
No.
20
10
20
10
10
10
10
10
Max.
99.7
6.26
630
190
9.12
0.65
41.8
17,000
Mean
65.9
6.1
504.0
156.3
9.33
0.64
35.6
-
Min.
10.3
4.28
24.5
12.0
3.28
0.19
4.0
250
r: Kiehldahl **: Soxhlet method
BOD
S-BOD
SS
VSS
T-N
T-P
Grease
Total
MPN
6 Apr., 75
Sample
No.
27
14
27
14
14
14
14
14
Max.
142
17.9
863
226
18.8
0.55
57.9
40,000
Mean
57.0
10.9
423.3
92.5
7.27
0.29
16.0
-
Min.
11.3
5.9
10.4
4.0
3.75
0.05
2.1
370
Summary
Mean
54.7
8.4
344.6
99.9
7.4
0.48
16.9
-
Range
980 ~ 9.5
70-2.2
2,561-6.3
1,360-1.0
71-0.6
2.96-0.05
538-0.1
500,000-2
*: Kiehldahl * *: Soxhlet method
407
-------
Table 9 Quality of Urban Stormwater (2)
(Midorichyo, Yamagata)
BOD
S-BOD
SS
VSS
T-N*
T-P
Grease**
Total
MPN
19 Sep., 74
Sample
No.
48
24
48
24
24
24
24
24
Max.
20.3
8.7
103.0
47.5
3.9
0.6
13.0
64,000
Mean
6.90
3.61
37.6
19.0
0.87
0.18
8.50
-
Min.
3.1
1.8
8.3
3.6
N.D
0.09
4.3
1,100
15 Oct., 74
Sample
No.
30
15
30
15
15
15
15
15
Max.
55.4
35.6
131.0
76.5
11.2
1.67
11.8
120,000
Mean
45.7
11.4
79.6
23.4
3.42
0.77
7.75
-
Min.
24.2
12.2
59.5
39.0
1.8
0.42
5.4
600
22 No., 74
Sample
No.
48
24
48
24
24
24
24
24
Max.
70.4
50.3
175.7
116.7
0.3
0.57
15.9
9,200
Mean
35.8
10.0
93.9
33.3
0.08
0.19
8.95
-
Min.
18.3
8.9
27.7
28.2
N.D
0.06
4.1
220
14 Dec., 74
Sample
No.
18
9
18
9
9
9
9
9
Max.
60.7
52.4
279
20.7
0.3
0.29
23.7
610
Mean
39.8
15.3
246.7
8.72
0.12
0.18
19.2
-
Min.
25.0
21.0
222
11.9
N.D
0.12
15.2
210
Summary
Mean
32.0
10.1
114.5
21.1
1.12
0.33
11.1
-
Range
70.4 -3.1
52.4-1.8
279-8.3
117~11.9
11.2-N.D
1.67-0.06
23.7-4.1
120,000-210
o
OO
*: Kjehldahl **: Soxhlet method
-------
Table 10 Quality of Urban Stormwater (3)
(Shimizugawa, Gifu)
^^^
^\
BOD (mg/e)
SS (mg/£)
VSS (mg/£)
^\^^_
^\
BOD (mg/2)
SS (mg/£)
VSS (mg/£)
6 July., 67
Samples
40
40
40
Max.
14.3
268.0
116.0
Mean
11.6
145.0
75.0
Min.
3.83
18.0
10.0
19 July., 67(1)
Samples
44
44
44
Max.
14.2
476.0
110.0
Mean
8.7
251.8
62.0
Min.
4.03
46.0
24.0
12 July., 67(1)
Sample
82
82
-
Max.
13.1
78.0
-
Mean
7.3
43.0
-
Min.
3.2
30.0
-
19 July. ,67(2)
Sample
34
34
-
Max.
10.7
88.0
-
Mean
6.8
45.2
-
Min.
5.04
13.4
-
12 July. ,67 (2)
Sample
65
65
-
Max.
11.3
162.0
-
Mean
7.3
71.0
-
Min.
4.11
9.0
-
22 Aug., 67
Sample
85
85
-
Max.
13.9
208.0
-
Mean
7.2
113.0
-
Min.
3.43
57.5
-
\
Summary
Mean
8.15
111.5
68.5
Range
3.2-14.3
9.0-476.0
10.0-116.0
o
to
-------
Table 11 Comparison of Quality (Strength) of Storm Water Discharges
City
Ann Arbor, Michigan
Des Moines, Iowa
Durham, N.C.
Los Angeles, Calif.
Madison, Wisconsin
New Orleans, La.
Sacramento, Calif.
Tulsa, Oklahoma
Washington, B.C.
Hanakuma, Kobe
Midoricho, Yamagata
Shimizugawa, Gifu
BOD5
Ave.
28
36
32
9.4
—
12
106
11
19
55
32
8
COD
Ave.
—
-
224
-
—
—
58
85
335
_
-
-
SS
Ave.
2,080
505
-
1,013
81
26
71
247
1,697
345
279
112
Total
MPN/100 mfi
—
—
3 x 10s
-
—
1 x 106
8.10s
1 x 10s
6xl05
410 -
-------
Table 12 Estimated Annual Load of Pollutants from Urban Land
Pollutant
Flow (103 m3/year)
BOD (t/year)
SS (t/year)
TKN (t/year)
Seconda
effluen
145,990
2,845
3,712
2,801
ry
t
%
92.6
73.1
67.1
95.4
Prima
efflue
2,205
267
306
58
ry
nt
%
1.4
6.9
5.5
2.0
Combinec
overfl
9,486
111
1,518
78
sewer
3W
%
6.0
20.0
27.4
2.6
411
-------
-pi
I—1
oo
Q
m3/S
SOH
BOD, SS
mg/C
k 600
40-\
500
Uoo
30H
-300
20H
\-200
uoo
12:00
13:00
14:00
' 0
o—oSS
A—ABOD
15:00
16:00 17:00
Time
Fig. 1 Relationship BOD, SS to Rainfall (1 March 73, Yabatagawa, Tokyo)
18:00
0 mm/h
10
20
30
19:00
20:00
-------
-pi
I—1
01
m3/S
U700
50-
-600
40--500
30-
10-
BOD, SS
rng/2
-400
-200
-100
13:00
14:00
Q
. BOD
)SS
18:00
15:00 16:00 17:00
Time
Fig. 2 Relationship BOD, SS to Rainfall (25 Aug. 73, Yabatagawa Tokyo)
19:00
0 mm/h
10
20
30
20:00
-------
-Pi
20
10 -
5:00
6:00 7:00
5:00
9:00 10:00
Time
11:00 12:00
13:00 14:00
f\Q. 3 Relationship BOD, SS to Rainfall (10 Nov. 73, Yabatagawa, Tokyo)
-------
1000-
BOD load (g/sec)
BOD cone. (mg/C)
Flow rate (m3/sec)
6:00
7:00
8:00 9:00
Time
10:00
11:00
12:00
13:00
14:00
\9. 4 Variation of BOD Load & BOD Concentration (10 Nov. 73, Yabatagawa, Tokyo)
-------
10:00
m3/sec)
0.06
0.05
0.04
-0.03
0.02
0.01
13:30
Time
Fig. 5 Heavy Metals Contained in Urban Stormwater (22, Nov. 1974, Midorichyo, Yamagata)
-------
Ul
Lo
131 K
321
626
3perBOD|
werSS J
255 S
L190
371
Primary
Treat-
ment
, 161
201 *^>
Secondary
Treat-
ment
^
1 I 38
\S 47
\
BOD
SS
Re-
moval
70l
173
Effi-
ciency
22%
28
Fig. 6 Annual Load of Pollutants from Combined Sewer Overflows,
Yabatagawa, Tokyo. . (t/Y)
Up
Lo
K
321
626
t/y
per BOD
werSS
321
626
321
626
124 \
242 /
/
197
384 K
K
124 \
242 /
197
384
V
K
124 \
242 /
V
197
384
N
>
Secondary
Treatment
TT82
1 I161
Storage Tank
Secondary
Treatment
n
Storage Tank
Secondary
Treatment
f>H3
I | 280
Storage Tank
45
68 h
>
91
123 K
,>
54
81
57
59 K
>
59
88 N
k>
37
31 K
>
27,000m3
"\
BOD
SS
Re-
moval
1851
435
Effi-
ciency
58%
69
54,000 m3
^\
BOD
SS
Re-
moval
2101
486
Effi-
ciency
65%
78
81,000m3
\^
BOD
SS
Re-
moval
225*
507
Effi-
ciency
70%
81
V
Fig. 7 Estimated Effect of Storage Tank, Yabatagawa Tokyo
417
-------
Fourth'US/JAPAN Conference
on
Sewage Treatment Technology
Paper No. 8
CASE STUDIES OF INDUSTRIAL WASTEWATER
TREATMENT
October 29, 1975
Washington, D. C.
Ministry of Construction
Japanese Government
418
-------
CASE STUDIES OF INDUSTRIAL WASTEWATER TREATMENT
1. Material Balance of Heavy Metals in Sewage Treatment Process 420
Mr. Ken Murakami, Chief, Water Quality Section, Water Quality Control
Division, Public Works Research Institute, Ministry of Construction
2. Torihama Industrial Wastewater Pretreatment Plant in Yokohama
— Operation and Maintenance — 45]
Mr. Masayuki Sato, Director, Sewage Works Bureau, City of Yokohama'
3. Fukashiba Industrial Wastewater Treatment Plant in Ibaragi Prefecture . . . .466
Mr. Satoru Tohyama, Head, Sewage Works Division, Department of
Sewarage & Sewage Purification, Ministry of Construction
4. Design and Operation of Dying Waste Treatment Facility in Sabae City,
Fukui Prefecture 477
Dr. Mamoru Kashiwaya, Head, Water Quality Control Division, Public Works
Research Institute, Ministry of Construction
5. Improvement of Effluent Quality of Bisai District Sewage Treatment Plant
in Aichi Prefecture 489
Dr. Mamoru Kashiwaya, Head, Water Quality Control Division, Public
Works Research Institute, Ministry of Construction
419
-------
CHAPTER 1. MATERIAL BALANCES OF HEAVY METALS IN SEWAGE
TREATMENT PLANTS
1.1 Effects of Cadmium, Lead and Mercury on the Biological Treatment
Process . 421
1.1.1 Effects of Cadmium on the Biological Treatment 421
1.1.2 Effects of Lead on the Biological Treatment 422
1.1.3 Effects of Mercury on the Biological Treatment 423
1.1.4 Summary 424
1.2 Influent Heavy Metal Concentration and Its Loading Balance in the Sewage
Treatment Plants 425
1.2.1 Sewage Treatment Plants Surveyed and Outline of Survey 425
1.2.2 Results and Discussion 426
1.2.3 Summary 427
420
-------
1. MATERIAL BALANCES OF HEAVY METALS IN SEWAGE TREAT-
MENT PLANTS
1.1 EFFECTS OF CADMIUM, LEAD, AND MERCURY ON THE BIOLOGICAL
TREATMENT PROCESS
The Public Works Research Institute, Ministry of Construction has, during the
past three years or so, conducted experiments using bench scale activated sludge
apparatus to clasify effects of cadmium, lead, and mercury, on biological treatment
process and material balance of heavy metals in the process.
The laboratory apparatus used is shown in Fig. 1.1. The apparatus was modified
so that it can collect vaporized mercury when experimenting on mercury.
Table 1.1 shows the design data and loading factors of the experiments. Sewage
used in the experiments is synthetic sewage and ingredients are shown in Table 1.2.
Cadmium, lead, and mercury were added to sewage in the forms of cadmium sulfate,
lead nitrate, and mercuric chloride, respectively.
The acclimatization period was taken about two weeks from the day the heavy
metal addition was started.
1.1.1 EFFECTS OF CADMIUM ON THE BIOLOGICAL TREATMENT
i) Experiments was made at each of three levels of cadmium in the influent feed,
0.1, 1.0, and 10mg/l.
ii) Average effluent quality obtained are shown in Table 1.3. In the case of influ-
ent with the cadmium concentration of 1 mg/1, no influence appeared on the
effluent. But one containing 10 mg/1 of cadmium experienced lowering of the
transparency of the effluent and increase in SS and BOD. As for soluble BOD,
no significant differences have been seen during all the experiments, but
insoluble BOD in the effluent increased as cadmium concentration of sewage
become higher.
From the relations between heavy metal content in activated sludge and those
in SS of the effluent, which are shown in Table 1.4, it was conjectured that SS
of the effluent is composed of organisms lighter than activated sludge, or their
debris.
In the case of influent containing 1 mg/1 of cadmium, cadmium concentration
of the effluent was approximately 0.3 mg/1. Cadmium in the effluent was most-
ly a insoluble.
iii) Characteristics of activated sludge are shown in Table 1.5.
Relations between cadmium concentration in sewage sludge production and
oxydation rate of sludge are shown in Fig. 1.2.
Transfer rate of removed BOD into sludge was about 0.5 when cadmium con-
centration was 1 mg/1, and about 0.7 when the concentration was 10 mg/1.
These results may indicate that when heavy metals exist in sewage, excess ac-
tivated sludge will increase.
Existence of cadmium in sewage has changed the fauna in activated sludge:
protozoa died out and it became composed mostly of bacteria.
When cadmium concentration in the culture medium by batch culture is less
421 -
-------
than 10 mg/1, the growth rate of bacteria separated from activated sludge
showed no significant difference against the control.
iv) Fig. 1.3 shows relations between cadmium content in activated sludge and cad-
mium concentration in the influent. This Figure clearly shows that cadmium
content in activated sludge varies depending on cadmium concentration in the
influent.
In 10 or so days after cadmium addition was started cadmium concentration in
sludge became almost constant.
"Concentration factors" were approximately 28 x 103 when influent cadmium
concentration was 0.1 mg/1 and 1.0 mg/1, and 9 x 103 when it was 10 mg/1.
These results were similar to those obtained in surveys at sewage treatment
plants.
v) Table 1.6 shows the material loading balance of cadmium in the process. "Unac-
counted for" in this Table is a value subtracted cadmium in effluent and in-
excess activated sludge from that in influent. It is considered that this "unac-
counted for" includes errors due to sampling of MLSS for analysis and those in
measuring growth of activated sludge. In experiments on sewage containing
10 mg/1 cadmium, pink-yellowish substance like cadmium sulfide was perceived
on the wall of the aeration tank. This substance is also considered to be in-
cluded in "unaccounted for."
Assuming that the "unaccounted for" flowed out as excess sludge, over 80% of
it is considered to transfer into the sludge treatment process, when cadmium
concentration is less than 1 mg/1.
As influent cadmium concentration increases, percentage of cadmium existing
in effluent as insoluble form becomes higher. In the case of 1 mg/1 of cadmium,
about 80% of cadmium flowing out together with effluent was insoluble.
1.1.2 EFFECTS OF LEAD ON THE BIOLOGICAL TREATMENT
i) Experiments was made at each of five levels of lead in the influent feed, 0.1,
0.25, 1.2, 7.9, and 95.5 mg/1.
ii) Average effluent quality obtained are shown in Table 1.7. When lead concentra-
tion in influent was 1 mg/1, no influence appeared on the effluent. When the
concentration was 8 mg/1, transparency of effluent became lower and the
quantity of SS and insoluble BOD increased. Significant differences in the
soluble organic constituents in effluent were hardly perceived in each run.
From Table 1.4, it has been found that SS in effluent was due to the washout
of activated sludge.
Effects of lead on the biological treatment appeared when its concentration in
influent exceeds 8 mg/1. Symptom is a washout of activated sludge.
iii) Characteristics of activated sludge^are shown in Table 1.8.
As in the case of cadmium, sludge production tended to increase by the
addition of lead.
In the case of transfer rate of removed BOD into sludge, the results were similar
to those in experiments with cadmium. When lead concentration in influent
- 422 -
-------
was less than 8 mg/1, transfer rate of removed BOD into sludge was 0.3 to 0.4.
As for fauna in activated sludge, when influent contained 8 mg/1 of lead,
Volticella, Epistylis and Charchesium were perceived in a small quantity.
Toxicity of lead was examined by shaking culture using activated sludge in
which protozoa does not exist. As a result, when the concentration of lead was
less than 100 mg/1, the activity of activated sludge deteriorated temporarily.
But the recovery rate of activity of activated sludge was at the same level of
that of control.
iv) Fig. 1.3 shows relations between content of lead in activated sludge and lead
concentration in the influent.
In about a week after lead was added to the influent, the lead concentration in
activated sludge became a constant thus reaching a steady state.
The concentration factor was 8.8 to 11.1 x 103 when lead in influent was less
than 8 mg/1.
Because lead tends to produce insoluble compounds when mixed with influent,
it is considered that the state of lead in sludge is different from that of other
elements.
v) Table 1.6 shows the material loading balance of lead in the process. "Unac-
counted for" was similarly treated as with the case of cadmium. The quantity
of lead transferring into the sludge treatment process tended to increase as the
lead concentration in influent increased.
When the lead concentration in influent was less than 1 mg/1, 30 to 50% of lead
in effluent was discharged as insoluble form. And when the concentration was
8 mg/1, over 90% of lead flowed out was insoluble.
1.1.3 EFFECTS OF MERCURY ON THE BIOLOGICAL TREATMENT
i) Experiments was made at each of three levels of mercury in the influent feed,
4, 100 and 1,000 mg/1.
ii) Average effluent quality obtained are shown in Table 1.9. When mercury in
effluent was 4 /ug/1, SS, COD, etc. of effluent increased and transparency de-
creased.
As in the case of cadmium, SS in effluent is considered as organisms lighter than
activated sludge or their debris (Table 1.4).
It seems that effects of mercury on the biological treatment are observed when
the mercury in influent exceeds 4 jug/1.
Hi) Table 1.10 shows characteristics of activated sludge. Sludge production showed
the same tendencies as with cadmium and lead.
Transfer rate of removed BOD into sludge was 0.4 when mercury in influent
was 4 jug/1 and about 0.5 when it was 1 mg/1. The same rate of control was
. about 0.3.
When mercury in influent was less than 4 jug/1, protozoa was perceived in
activated sludge. But when the mercury concentration was lOO^g/1, bacteria
similar to zoogloea were dominant.
iv) In the biological treatment, when mercury in influent was about 1 mg/1, the
423
-------
amount of vaporized mercury was aproximately 17 /ug/day/g.SS. In other runs
with mercury, quantitative analysis of vaporized mercury was impossible.
State of vaporization of mercury in aeration tanks is shown Fig. 1.4. As clearly
shown in the Figure, it has been found that most of mercury to be vaporized in
aeration tanks is vaporized at the first quarter of the path of the tanks.
v) Relations between mercury content in activated sludge and mercury concentra-
tion in influent are shown in Fig. 1.3.
As a result of measurement by a gaschromatograph whose sensitivity is 0.01 mg
alkyl-mercury/kg.SS alkyl-mercury was not detected in activated sludge.
Concentration factor was 42 x 103 when mercury in influent was about 4 jug/1.
vi) Table 1.6 shows material loading balance of mercury in the process.
Unlike in the cases of cadmium and lead, when mercury in influent was about
4 jug/1, the total of mercury discharged as effluent and vaporized mercury was
some 10%. Therefore, mercury is easily accumulated in sludge.
Around 50% of effluent mercury was insoluble.
1.1.4 SUMMARY
1) When cadmium, lead, or mercury is contained in sewage, the minimum concen-
tration of them which gives effects on the biological treatment is as follows:
Cadmium 1 to 10 mg/1
Lead approx. 10 mg/1
Mercury approx. 5 jug/1
Actual effects of these heavy metals on the biological treatment appeared in the
form of decrease in transparency of effluent and increase in SS.
Within the above-mentioned level of heavy metal concentration, there were vir-
tually no effect of them on removal of organic matters.
2) In cases of cadmium and mercury, SS in effluent showed those characters which
no protozoa existed in activated sludge. In the case of lead, SS in effluent was
due to the washout of activated sludge.
3) By the addition of heavy metals, the fauna of activated sludge was changed:
while protozoa decreased in number, bacteria became dominant species.
Within ranges of concentration of heavy metals in the present experiments,
growth rate of bacteria separated from activated sludge was hardly affected.
4) Heavy metals in influent tended to accelerate sludge production. This is con-
sidered, from 3) above, to be caused by the difference in food chain of
organism in activated sludge.
5) Accumulation of heavy metals on activated sludge depends upon their concen-
tration in influent.
6) Concentration factor of the heavy metals was around 104. Most of heavy metals
contained in influent is transferred to the sludge treatment process.
7) Outline of effects of each element on the biological treatment process is shown
in Table 1.11.
424
-------
1.2 INFLUENT HEAVY METAL CONCENTRATION AND ITS LOADING
BALANCE IN THE SEWAGE TREATMENT PLANTS
In Japan, the concern in the effects of heavy metals in the sewage upon the
activated sludge process is veering round toward the extent to which the heavy
metals, though little in quantity, in the sewage are entrained into the sludge through
the biological treatment process, rather than toward the interference with the biolo-
gical treatment itself.
This is because as the environmental standards and pretreatment facilities ef-
fluent standards have been established it is almost unlikely so far as municipal sew-
age treatment plants are concerned that heavy metals will run into them at as high
concentrations as to interfere biological treatment.
On the other hand, it is noticed that even if heavy metals in the influent is a
trace level, they can accumulate to amass their concentrations in the sludge. This
fact urges the collection of information about the relationship between the concen-
trations of heavy metals in the influent sewage and those in the sludge.
Dealt with here are the concentrations of heavy metals contained in domestic
sewage, concentrations of heavy metals accumulated in sludge and heavy metal bal-
ance in the sewage treatment plant which are discussed based on the results of
survey on the sewage treatment plants treating domestic sewage alone and those
taking in industrial effluents combined with domestic sewage.
1.2.1 SEWAGE TREATMENT PLANTS SURVEYED AND OUTLINE OF SUR-
VEY
A field survey was conducted from July 1973 to September 1974. The sewage
treatment plants surveyed included two domestic sewage treatment plants located
near residential areas and two comparatively large municipal waste treatment plants.
The latter two were picked up as typical of those treating municipal sewage and
not as special problem solvers of industrial wast water.
These four sewage treatment plants are outlined in Table 2.1.
Plant "A" is a medium-sized one which is estimated to have been receiving
some 8,000 m3 /d from industries suspected to discharge heavy metals out of its total
daily processing rate of 50,000 m3.
Plant "B" comes under the catagory of large-scale plants. It has been treating
400,000 m3 /d of which some 200,000 m3 /d are accounted for by industrial waste-
water, and is estimated to have been receiving at least about 2,000 m3 /d from indus-
tries likely to discharge heavy metals.
Plants "C" and "D" are small-scale ones in the residential areas which are not
receiving industrial wastes at all.
All these plants are undertaking the conventional activated sludge process after
primary treatment. The flow diagram is all the same.
Plants "A" and "D" have their sludge treated at nearby sludge treatment plants.
Plants "B" and "C" are practising anaerobic digestion of sludge, and the supernatant
to be developed in the sludge treatment process is returned to the head of the pri-
mary settler.
- 425 -
-------
The survey was conducted with one day as a unit. The sampling was conducted
for 24 consecutive hours; some samples were gathered into a composite one, and
some others were handled as grab samples.
1.2.2 RESULTS AND DISCUSSION
Concentrations of heavy metals in domestic sewage
Table 2.2 shows the mean values and range of concentrations of heavy metals
in the domestic sewage obtained at plants "C" and "D".
Copper, chromium, cadmium, lead, nickel, zinc and mercury were measured.
As shown in Table 2.2, all these seven heavy metals were detected.
The concentration of zinc was the highest with the order of 10~2 to 10"1, fol-
lowed by copper with 10~2, chromium, nickel and lead with 10"3 to 10~2, cadmium
with 10"3 and mercury with 10"4, all in terms of mg/lit.
From what these heavy metals come is still unknown, but foods, plumbings,
kitchen utensils and the like are suspected. It is also reported that cadmium and
mercury are deeply concerned with foods.
Accumulation of heavy metals in sludge
Primary sludge and waste activated sludge sampled from each plant were meas-
ured for heavy metals.
Figs. 2.1 and 2.2 show the relationships between the concentrations of heavy
metals in the influent sewage and those in the primary sludge and waste activated
sludge.
For both, daily average values are taken. It is evident from the figures that the
concentrations in the influent have a great bearing on the concentrations in the pri-
mary sludge and waste activated sludge. The straight lines appearing in the figures
show the multiples (accumulation coefficients) of the concentrations in influent and
sludge.
The concentrations of heavy metals in the influent sewage were as small as less
than 1 mg/lit., and the laboratory test results explained in Chap. 1, and the results of
field survey and laboratory tests conducted by Taft Center, U.S.A. are annexed in
order to corroborate the above findlings. (See Figs. 2.3 and 2.4.)
As a result, there are found the interesting facts as follows.
1) In the case of primary sludge, when the concentrations of heavy metals in the
influent sewage exceed 10 mg/lit., the relationship between the concentrations
in the influent and those in the sludge loses linearity, with the result that the
concentrations in the sludge become in a specified range (1 to 10 mg/SSg)
2) In the case of waste activated sludge, even when the concentrations in the in-
fluent sewage go up to 100 mg/lit., it does not matter to the linearity; namely,
the concentrations of heavy metals in the waste activated sludge increase on
and on.
Considering these and other various factors, the following may be said about
the accumulation of heavy metals in the sludge in the sewage treatment plant.
1) At sewage treatment plants operated under ordinary conditions, the concentra-
426
-------
tions of heavy metals in the sludge are closely related with those in the influent
sewage, though dependent on the kinds of heavy metals.
2) The multiples (accumulation coefficients) lie in the range of 103 to 104, and
104 should be taken up if safety factor is considered.
3) In the case of primary sludge, the linear relationship between the concentra-
tions of heavy metals in the influent sewage and those in the sludge is lost when
the former exceeds 10 mg/lit., and thus the concentrations of heavy metals in
the sludge remain within the range of 1 to 10 mg/ssg.
4) The field surveys at sewage treatment plants could not clarify the difference in
accumulation rate between metals.
5) The sludge delivered from the sewage treatment plants processing domestic
sewage alone also concentrate heavy metals. According to the measurements at
plants "C" and "D", the heavy metals are estimated to have been concentrated
to the levels given below.
Copper: 100 ~ 1,000 mg/kg; zinc: 100 ~ 10,000 mg/kg; chronium, nickel &
lead: 10 ~ 1,000 mg/kg; cadmium: 10 ~ 100 mg/kg; mercury: 1 ~ 10 mg/kg.
Heavy metals balance in the sewage treatment plant
As regards plant "B" where supernatant is sent back to the head of the primary
settler from the sludge treatment system, the results of heavy metals balance between
facilities are shown in Table 2.3.
The figures are all based on actual observation. The run-in and run-off values of
each facility are given with the total amount of heavy metals in the influent sewage
taken as 100.
Namely, run-in and run-off amounts of each facility are divided by the amount
in the influent sewage. The following are found by twice surveys.
1) Nickel and cadmium are liable to remain in the effluent. As regards cadmium,
this tendency is considered attributable to its relatively low concentration in
the influent sewage.
2) The amount of heavy metals conveyed by recycled waste such as supernatant of
anaerobic digester is by far the more larger than that in the influent sewage; in
some cases, it becomes 4 times as large.
3) Almost all of heavy metals contained in the recycled waste are insoluble.
4) Accordingly, they are settled easily in the primary settler, and are recycled be-
tween the sludge treatment system and sewage treatment system. The concen-
trations of heavy metals in the influent sewage become almost equal to those in
the primary effluent.
1.2.3 SUMMARY
1) Domestic sewage contains heavy metals, whose concentrations are found to be
in certain ranges.
2) It is disclosed that the accumulation of heavy metals in the sludge is closely
related to the concentrations of heavy metals in the influent sewage.
427
-------
3) The accumulation coefficient is in the order of some 104 irrespective of the
kinds of heavy metals, and when the concentrations in the influent sewage are
once clarified, the concentrations in the sludge can therefore be estimated.
4) An actual example of material balance concerning heavy metals in the sewage
treatment plant is given.
428
-------
Table 1.1 Design Data and Loading Factor (Bench scale activated
sludge apparatus)
Apparatus design data and loading factors
Aeration tank
Capacity
Aeration period
Return sludge rate
BOD loading
00
(%)
(kg/day/kg, ss)
60
4
25
0.3
Final settler
Capacity
Detention time
Surface overflow rate
00
(//day/cm2)
24
1.6
0.87
429
-------
Table 1.2 Composition of Synthetic Sewage (mS/0
Substrate
Glucose
Dextrin
Meat extract
Peptone
Yeast extract
Concentration
17.6
17.6
80.0
80.0
90.0
Substrate
Urea
KC/
NaC/
MgS04
KH2 PH4
Concentration
37.0
8.1
8.1
5.4
24.5
BOD = 180mg//
-------
Table 1.3 Average Characteristics of Effluents for Control and Cadmium-fed Apparatus S: Soluble matter
o-i
No.
(Cd in influent)
'A
(0 mg/fi)
B
(0.1)
c
(1.0)
D
(12.4)
Trans.
30<
13— 30<
11~30<
21
15~25
PH
5.8~6.9
5.6~6.6
5.6-7.0
6.8-7.3
SS
(mg/2)
36.3
16~104
50.7
2-140
51.0
10 — 108
82.4
34—144
B(
(mg/£)
8.68
6.96
6.94
12 A
)D
S(mg/£)
0.96
1.09
0.57
0.99
Percent removal
94.2
95.2
95.2
91.4
Cd
(mg/£)
-
0.022
0.30
6.91
S(mg/£)
-
0.013
0.049
1.04
Percent removal
-
80.0
71.1
44.2
-------
Table 1.4 Metal Content in Activated Sludge and SS of Effluent
Metal
Cd
Pb
Hg
No. (Metal in influent)
A (0 mg/2)
B (0.11)
C (1.04)
D (12.4)
A (0)
B (0.1)
C (0.25)
D (1.2)
E (7.9)
F (95.5)
A (0)
B (0.004)
C (0.974)
Content of metal in sludge (mg/g. ss)
Aa
-
3.08
29.6
113
-
0.99
2.23
13.3
61.6
534
-
0.187
13.2
Ab
-
0.2
4.9
71.2
-
0.85
1.95
12.7
256
378
—
0.022
0.082
Aa/Ab
-%
6.5
16.6
62.8
-
85.9
87.4
95.6
-
70.8
-
11.8
0.6
Aa: Metal content in activated sludge, Ab: Metal content in SS of effluent
-------
Table 1.5 Effect of Cadmium on Activated Sludge
No.
(Cd in influent, mg/£)
A (0)
B (0.1)
C (1.0)
D (12.4)
MLSS
(mg/£)
3,814
2,818
2,957
2,702
MLVSS
(mg/£)
3,443
2,519
2,567
2,294
MLVSS
/MLSS
0.90
0.89
0.87
0.85
SVI
214
289
239
283
BOD 'loading
(kg/day/kg, ss)
0.23
0.31
0.30
0.32
Cd loading
(mg/day/g. ss)
-
0.17
2.1
27.5
Sludge production rate (g/day)
as SS
19.4
24.6
27.9
38.7
as VS
17.5
21.9
24.3
32.9
Content of Cd in
sludge (mg/g. ss)
-
3.08
29.6
113
Concentration
factor
-
28 x 103
28 x 103
9xl03
-------
Table 1.6 Balance of Metals in Activated Sludge Process
Metal
Cd
Pb
Hg
No.
(Concentration in influent)
B (0.1 mg/0'
C (1)
D (10)
B (0.1)
C (0.25)
D (1.2)
E (7.9)
F (95.5)
B (4.4 PMg/2)
C (119)
D (974)
Material balance (%)
Effluent
20.1
28.8
55.8
55.6
27.3
32.6
81.7
10.6
5.27
1.57
0.34
Vapor
—
-
-
—
-
-
-
-
4.11
1.27
0.31
Excess activated sludge
51.3
78.3
23.1
22.2
41.5
29.1
19.8
44.7
62.3
83.6
89.0
Unaccounted for
28.6
—
21.1
22.2
31.2
38.3
—
44.7
28.3
13.6
10.4
-------
Table 1.7 Average Characteristics of Effeuents for Control and Lead-fed Apparatus
No.
(Pb in influent)
A -(0 mg/fi)
B (0.1)
C (0.25)
D (1.2)
E (7.9)
F (95.5)
Trans.
29.6
30 <
30 <
30 <
26.1
20.0
PH
6.9
7.0
7.3
7.0
6.4
6.7
SS
(mg/£)
7.60
21.2
12.8
14.2
23.2
25.7
B(
(mg/£)
7.05
12.26
8.04
8.10
15.25
(5.16)
DD
S(mg/£)
2.21
1.73
1.49
1.68
1.50
(1.32)
Percent removal
95.3
91.5
94.6
94.5
88.7
(96.4)
C(
(mg/£)
9.22
11.83
7.27
7.31
9.92
7.60
DD
S(mg/£)
6.17
7.12
5.62
5.71
5.55
4.82
Percent removal
86.2
73.9
84.6
88.2
84.6
87.2
PI
(mg/£)
-
0.056
0.070
0.39
6.47
10.08
3
S (mg/fi)
-
0.038
0.045
0.21
0.54
0,36
Percent removal
-
43.6
29.7
67.5
18.3
89.4
-------
Table 1.8 Effect of Lead on Activated Sludge
No.
(Pb in influent, mg/£)
A (0)
B (0.1)
C (0.25)
D (1.2)
E (7.9)
F (95.5)
MLSS
(mg/£)
2,419
2,263
2,280
1,474
1,751
12,860
MLVSS
(mg/£)
2,201
1,969
1,987
1,340
1,384
3,342
MLVSS
/MLSS
0.91
0.87
0.87
0.91
0.80
0.27
SVI
318
90
95
480
123
30
BOD loading
(kg/day/kg, ss)
0.64
0.40
0.40
0.59
0.56
0.08
•Pb loading
(mg/day/g. ss)
-
0.273
0.700
5.90
308
476
Sludge production rate (g/day)
as SS
9.4
14.9
21.2
14.4
17.3
22.0
as VS
8.5
13.0
18.5
13.1
13.9
6.0
Content of Pb in
sludge (mg/g. ss)
-
0.99
2.23
13.28
61.6
534
Concentration
factor
-
9.8 xlO3
8.8 x 103
11.1 xlO3
9.8 x 103
5.6 x 103
-fa.
O-l
-------
Table 1.9 Average Characteristics of Effluents for Control and Mercury-fed Apparatus
No.
(Hg in influent)
A
(0 Mg/£)
B
(4.4)
C
(974)
A'
(0)
D
(119)
Trans.
30
21.3
20.3
30
30
PH
7.0
7.3
7.3
7.0
7.0
SS
(mg/£)
3.5
25.5
20.0
-
-
B<
(mg/£)
4.42
8.13
18.40
4.55
4.57
3D
S(mg/£)
0.98
2.05
3.66
0.79
0.70
Percent removal
96.8
93.9
85.6
95.3
95.3
CC
'(mg/£)
6.43
12.30
18.50
8.68
18.33
)D
S(mg/£)
4.97
5.71
7.85
7.81
9.11
Percent removal
88.9
79.2
67.7
87.0
63.4
H
(Mg/£)
-
0.97
3.35
-
1.87
g
S(Mg/£)
-
0.41
1.72
-
1.34
Percent removal
-
78.3
99.7
-
98.4
-------
Table 1.10 Effect of Mercury on Activated Sludge
No.
(Hg in influent, Mg/£)
A (0)
B (44)
C (974)
A' (0)
D (119)
MLSS
(mg/g)
1,351
1,676
1,065
2,077
1,437
MLVSS
(mg/£)
1,174
1,473
956
1,830
1,236
MLVSS
/MLSS
0.87
0.88
0.90
0.88
0.86
SVI
644
482
688
421
324
BOD loading
(kg/ day/kg, ss)
0.57
0.47
0.75
0.21
0.24
Mercury loading
(Mg/day/g. ss)
-
15.98
5,490
-
410
Sludge production rate (g/day)
as SS
15.9
31.4
30.8
10.3
12.5
as VS
13.8
27.6
27.7
9.1
10.8
Content of Hg in
sludge (Mg/ss. g)
3.22
187
1.34 x 104
3.05
2.87 x 103
Concentration
factor
-
42 x 103
14xl03
-
24 x 103
OO
I
-------
Table 1.11 Summary of the Result
Metal
Cd
Pb
Hg
Expected maximum
concentration in influent
0.1 rng/g
1.0
5 Mg/e
Highest dose of metal for satis-
factory biological treatment
1~10 mg/e
(5)
10
>5 Mg/£
Percent removal
BOD
95
95
94
Metal
80
70
80
Content of metal in
sludge (mg/ss. g)
3
Concentration
factor
(28 x 103)
13
(11 xlO3)
0.2
(42xl03)
Growth of
sludge
M d/day)
0.1455
Control
(0.0848)
1.72*
0.1629
(0.0644)
2.53*
0.3125
(0.1957)
1.60*
*: Ratio against control
-------
Table 1.12 Outline of STP Surveyed
~~~ — — - — _____Name of STP
Item - — -—_ __
Area served (ha)
Population served
Daily average flow (m3/d)
Collection system
Secondary treatment system
Remarks
A
1,134
139,000
53,000
Combined sewer
Conventional
activated sludge
B
2,939
498,600
400,000
Combined
sewer
The same
as left
C
701
6,000
4,000
Separate
sewer
The same
as left
Domestic
sewage
D
748
46,000
20,000
Separate
sewer
The same
as left
Domestic
sewage
440 -
-------
Table 1.13 Heavy Metal Concentration in Domestic Sewage
(mg/C)
\JHeavy metal
STP~"~^--^
D, Feb. '75
D, Mar. '75
D, Feb. '73
D, Nov. '73
C, Sept. '73
C, Mar. '73
Cu
0.029
0.029
0.046
0.031
0.029
0.016
Cr
0.001
0.000
0.018
0.000
0.023
0.032
Cd
0.0012
0.0029
0.0022
0.0016
0.0026
0.0031
Pb
0.0025
0.0013
0.020
0.016
0.038
0.028
Ni
0.009
0.000
0.055
0.001
0.019
0.015
Zn
0.13
0.12
0.295
0.156
0.055
0.054
Hg
-
-
0.0000
0.0001
0.0002
0.0005
Remarks
3 day
average
3 day
average
A day
composit
A day
composit
A day
composit
A day
composit
- 441 -
-------
Table 1.14 Heavy Metal Loading Balance in Sewage Treatment Plant (Observed at B STP)
^~\^Heavy metal
Location ^^^^
1 Raw sewage
2 Superrnatant
Primary
Influent
Primary
Effluent
Final
Effluent
Concentration
in raw sewage
(mg/J2)
Cu
Total
100
100
478
16
519
129
103
90
13
17
Sol.
46
55
1
1
. 11
13
16
11
Insol.
54
45
477
15
508
90
74
2
17
0.137
0.111
Cr
Total
100
100
301
182
347
300
159
124
29
23
Sol.
85
48
1
3
41
37
46
32
29
Insol.
15
52
300
180
306
260
113
92
0
23
0.113
0.105
Cd
Total
100
100
423
175
253
233
219
144
294
67
Sol.
82
28
9
231
137
118
79
CO
Notes: 1. Number indicates raw sewage values of 100 or proportional relationship based on it.
2. Above Aug. Survey, Beneath, Mar. Survey.
©
Inf.
Discharge
Supernatant
Sludge Treatment Facilities
(Thickner, Anaerobic Digester, Vacuum Filter and Incinerator)
Schematic Flow Diagram of the B STP
-------
Air
r\
M
r~\
M
No.1 2
Aeration Tank
(7.5£x 8 tank)
I : Tap Water
II : Synthetic Sewage
III : Solution of Metal
P) : Pump
V
-=•
V
Effluent
Final Settler
(242)'
Fig. 1.1 Bench Scale Activated Sludge Apparatus
- 443 -
-------
40r
30
20
c
o
3
•a
o
£ 10
00
•a
X 1Q-7
' -.9
0
( Control )
E
CL,
00
T3
J3
to
Di
I
'H
T3
0.1
10
Cd in Influent (mg/2)
Fig. 1.2 Relationship Between Sludge Production and Oxidation Rate and Cd in Influent
- 444 -
-------
I
8 o.oi
0.001
—°Sludge ph
—"Effluent n
—o Sludge rj
—•Effluent ^
—A Sludge H
—A Effluent Hg
0.001 0.01 0.1 1
Metal in Influent (mg/fi)
100
10
10
0.1
0.01
0.001
c
-------
>,
cd
•O
oo
3
O
&
500
400
300-
200-
100-
0 •
Fig. 1.4 Vaporized Mercury in Each Aeration Tank
- 446 -
-------
10
so
n
?
I '
0
>-,
2
5 o.i
3
,>
3
!
<
0.01
0.001
n nnni
t,
/
/
/
7
/
Legend <
\
7
/
~?
~£
4
-,'-
Q +~
^
7
/
T4
/
4
O Cu
• Cr
V C'd
T Pb
0 Zn
• Ni
/
/
2
V
ss
/I
~7~~
7
7
f
/
7
*n
— = i
/
7
x* r
7
A STP
2. BSTP
3. C STP
4. D STP
/
/
'
/
/
/
4
x
7
/
cen
x
/
2
1
7
/
~7~
7
— 7-
£ ,
!•>--
s
z
— 7~
~£_
tration h
...
/
'o'
1'' 2
r
•2
/
D1*
/
actor
/
1
/
3
o
02
/
/
/
f
- -j -
7
\*
^
^
/
/
/
' -
/
/
/
/
/
/
/
— 7
^
~7*~~
/
/
/
/
/
/
— -*-
7
__2
^
0.01 0.1
Influent Heavy Metal Concentration (mg/G)
Fig. 1.5 Relationship between Influent Heavy Metal Concentration
and Content in Primary Sludge
- 447 -
-------
"ontent in Activated Sludge (mg/SS.g)
o - 3
^ — 0 o
s.
>
I
0.01
/
Xj
/
-
y
/
/
—
Legend t
2
2
,0
/
TTT
/
X
4
V
x<*'
/
—
o
a
A
/
4
f
X
3y
37-
x
Cu
Cr
Cd
Pb
N
"e
7
2
2
-^-
2
/
7
2
V
1 A STP
:. B STP
3. C STP
4. D STP
/
/
/
C
03
^
., 3>
31
-X
7
•3
/
cut
/
'
1
/
"
/
ut
3'jL
],. 3
If
T
-2^-
2
7^
on Fa
X
Q
1°
_._*?=
"I
- 2
/
:tor
/
1
/
i
Q
/
2
/
— 7
2
^
7
TD
i
• i
.
/
/
— T^-
/
/
"^
• ./
/
/
/
/
/
L*
2
._^z.
7
_ <^_
^/
— c
/
7
/
"fl
/
/"
/
7/
7
/
7
7!
^<
-?'
^
Influcnl Heavy Metal Concentration ( mg/C)
Fig. 1.6 Relationship between Influent Heavy Metal Concentration
and Content in Activated Sludge
- 448 -
-------
100
10
1
0.1
0.01
.001
1001
-
X
/
/
Legend
/
/
/
^
2
y
V
—I- T
0.
\
2 _
Jljl 1 -
-
O Cu
• Cr
J Vcd
f Pb
D Zn
• Ni
/
T4
/
/|
/
/
7
7
1
T
3
4.
5.
6.
7.
8.
^
y
£_
2
/
2
-gj/
y
/
^
/
N°
f: — — f--f- 1 -[ f
J-l ILt1" ~
1 LI 1_L
-4--H
-
•U-144 : 1
fljT T
i 1 4
tli i
ASTP
BSTP
CSTP
DSTP
Grand Rapids*
Richmond*)
Bryan*
In House (Tafl Center *)
/
/
/
/
6
|
/
/
/
2
2
-> T
— i ,2 -
^
7
/
s
centration
X
6
i
£-•:? —
t--12
f K
i
[ X
...
" n't
X
•'actor
/
A
a
7
/
/
-' =
TI~*
\i
r
— i -
1 ~*
£~^~
/
2
• /
i
6
5 5
O 1
/
/
•J
a
'
/
~s
/
2
8
, 6
?u
T
/ 8O
8
/'
/
~7
\ \ II
-Hk
S^ — (-p-
»y- s
i8
8
/
/O
s
7
y ~
....
: = !:
'8
Influent Heavy Melal Concentration (nig/V)
*) After "Interaction of Heavy Metals and Biological Sewage Treatment Processes" U.S. PUS. No.999-WP-22. 1965.
Fig. 1.7 Relationship between Influent Heavy Metal Concentration
and Content in Primary Sludge
449 -
-------
100
10
1
0.1
0.01
0.001
0.0001
-
<4
/
Legend
/
/
J
/
^/
— \- &
•$
/
Z _
/
0 Cu
• Cr
7 Cd
T Pb
D in
• Ni
_ AHg
/
"I — •
4V
r
*'
/
ASTP
2. BSTP
3. C STP
4. D.STP
5. Grand Rapids*)
6. Richmond*)
7. Bryan*)
8. In House (Taft Center *)
9. In House (PWRI)
/
4
/
3\
y
x°
/
I
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/
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~~?
~^_
1 5
,
7
4
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V
J
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• '
,7
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/
/
4
O
3O
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I . .
.
/
*
3
3
/
/
O
/
\—
^
2
1
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/
~?
*-
\
V
*
7
>
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t
2
~~?
2 ~
/
o
10
s\
02
h R
x
/*
1
V
D
2
/
32
/
_
z
rrir
6 *
>J
1 1
1
1
?
/^
z
/
/
2
""•^ Concentration Factor
9
y
Lv
f —
*i ~9~
i
3 ^ '
/
,..
/
A
,
/
/
5
/
^
^
-3.
r 8
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T
,'
— T^
2
3*
. ,
v9
9 R -
TT — °f
•
i «
/
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—
/
/
/
8
/
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fl
p-,
r
0.001 0.01 O.I 1 10
Influent Heavy Metal Concentration (mg/P)
*) Alter "Interaction of Heavy Metals and Biological Sewage Treatment Processes" U.S PHS, No999-WP-22. 1965.
Fig. 1.8 Relationship between Influent Heavy Metal Concentration
and Content in Activated Sludge
- 450 -
-------
CHAPTER 2
OPERATION OF TORIHAMA INDUSTRIAL WASTEWATER PRETREATMENT
PLANT IN YOKOHAMA
CONTENTS
Introduction 452
2.1. Outline of Industrial Wastewater Collective Pretreatment
Facilities in Torihama District 452
2.1.1. Features 452
2.1.2. Flow Sheets of Treatment Methods 452
2.2. Plant Operation 454
2.2.1. The Number of Advanced Enterprises and the Volume of Influent . . . 454
2.2.2. Results of Treatment 456
2.3. Operation and Maintenance Cost 459
2.4. Problems and Countermeasures 461
2.4.1. Problems on Management 461
2.4.2. Technical Problems 461
2.4.3. The Volume of Sludge Produced and Their Disposal 462
Conclusion 465
451
-------
Introduction
The outline of the facilities and treatment results obtained at the Torihama
Industrial Wastewater Pretreatment Plants were reported at the Third US/Japan
Conference on Sewage Treatment Technology as an example of "Joint Treatment of
Industrial and Domestic Wastewater"
Some improvements have been made on the facilities and operation at these
plants have been generally satisfactory from that time on. So we would like to
analyze the operational data obtained along with plant operation/maintenance cost
and technical problems to be solved.
2.1. OUTLINE OF INDUSTRIAL WASTEWATER COLLECTIVE PRETREAT-
MENT FACILITIES IN TORIHAMA DISTRICT
"Control over the sources" is the basic rule to follow and the same holds true
with industrial wastewater we have two approaches to choose from: separate
treatment at individual factories and collective treatment as a practical means to take.
Considering the fact that, at Torihama industrial district, some 90 percent of the
firms advanced into this industrial district are medium and small enterprises with
employees of 100 or less, we have adopted, rather than independent individual
treatment wastewater, joint pretreatment approach, to admit their wastewater into
public sewarage.
Major features and treatment methods are as follows:
2.1.1. FEATURES
(1) The construction and maintenance costs relating to the joint treatment of
industrial wastewater is a full charge to constituent enterprises, and the construction
and operation/maintenance activities are placed under the control of the City.
(2) Industrial wastewater is classified into three types: miscellaneous wastewater
(from water closets, kitchens, etc.), general process wastewater (containing organic
matter, oils, etc.), and pickling-plating process wastewater (discharged from pickling-
plating factories). Pickling-plating process wastewater is further divided into two
types, that containing cyanide and that contianing heavy metals. Each type of
wastewater is led to the treatment plant through separate piping and treated properly
according to its particular physical and chemical properties.
(3) Loans of comparatively low interest are being offered by the City to medium
and small firms as a public nuisance prevention fund to help them finance their shares
of the joint wastewater pretreatment plant construction costs.
2.1.2. FLOW SHEETS OF TREATMENT METHODS
Flow sheets of the treatment methods are shown in Fig. 2-1.
452 -
-------
Fig. 2—1 Flow-sheet showing treatment processes
at Torihama Industrial Waste Water Pretreatment Plant
Plant No.
Plant No. 2
(Heavy metals waste water)
(Cyanide waste water)
Pump
Pump
Primary oxidation
tank
Storage tank
Secondary
oxidation tank
Reduction tank
I
Mixing tank
Filtrate
Coagulation
sedimentation tank
-p*.
On
1
Sludge
Vacuum filter
Filter
1
pH controller
(General process
waste water)
Relay pump
(Miscellaneous
waste water)
Relay pump
Sludge
(NOTE)
Designed
capacities
Plant area
Miscellaneous
waste water
General process
waste water
_ Cyanide
waste water
Heavy-metals
waste water
r- Plant No. 1
L Plant No. 2
4,333m3/day
3,921 m3/day
60 m3/day
340m3/day
1,097m2
3,300m2
Sludge cake
Screen
Screen
Pump
Pump
Aerated grit
chamber
J_
Oil separator
I
pH controller
1
Mixing tank
I
Coagulation
sedimentation tank
I
Aerated grit
chamber
Thickener
Sludge storage
tank
Centrifuge
^Supernatant
Pressure pump
Sludge cake
tentrate
Nambu Sewage Treatment Plant
-------
2.2. PLANT OPERATION
The Torihama Pretreatment Plant No. 2 has been in operation since April of
1972, and the Torihama Pretreatment Plant No. 1 since March of 1973. During the
two or three years of their operation, later changes have been incorporated in the
facilities to improve capabilities of the facilities, and their operating performance is
generally satisfactory from that time on.
Servicing status from the beginning of plant operation until now is as follows:
2.2.1. THE NUMBER OF ADVANCED ENTERPRISES AND THE VOLUME OF
INFLUENT
The year-by-year increase in the number of constituent enterprises (firms
advanced into the industrial district) and the changes in the volume of influent during
the period from the end of March, 1973, to the end of March, 1975, are shown in
Table 2-1.
Although the advance of enterpirses into the industrial district was initially
expected to end by the summer of 1974, the depression by so-called "oil shock"
starting in late 1973 has been holding back the pace of advancement. And as of the
end of March, 1975, the advance rate (%) was approximately 76% with respect to the
object level, while the volume of influent was only 22% against the level originally
planned, a fact far behind the object level.
- 454 -
-------
Table 2—1 The number of advanced enterprises and the volume of waste water
N. Items
Type of \.
wastewater \
Miscellaneous
General process
Pickling and
plating process
Enterprises
Planned
169
108
6
End of
March
1973
55
15
-
End of
March
1974
82
31
4
End of
March
1975
128
65
5
Advanced
rate in end
of March
1975
76 (%)
60
83
Total
Wastewater
Planned
4,333m3 /day
3,921
400
8,654
End of
March
1973
511 m3/day
317
-
828
End of
March
1974
1,064m3 /day
990
157
2,211
End of
March
1974
1,121m3 /day
709
104
1,934
Rate in
end of
March
1975
26 (%)
18
26
22
01
en
-------
Particularly, the depression became apparent in every sector of the industry, and
enterprise operators' efforts concentrated on saving water consumption through
shorter-time operation and (or) improvements in processes resulted a decreased
drainage.
2.2.2. RESULTS OF TREATMENT
The qualities of influent and clarified water by type of sewage over the period
from January, 1975, to the end of May, 1975, are generally satisfactory and are
shown in Tables 2—2 and 2—3, respectively.
456
-------
Table 2-2 Results of Treatment at Plant No. 1 (Pickling/plating process wastewater)
Date
1975
1. 8
1.22
2. 5
2.20
3. 5
3.19
4. 2
4.30
5.14
5.28
Type of
wastewater
Cyanide
Metals
Effluent
Cyanide
Metals
Effluent
Cyanide
Metals
Effluent
Cyanide
Metals
Effuluent
Cyanide
Metals
Effluent
Cyanide
Metals
Effluent
Cyanide
Metals
Effluent
Cyanide
Metals
Effluent
Cyanide
Metals
Effluent
Cyanide
Metals
Effluent
Hue
Colorless
Yellow
Colorless
Light yellow
Yellow
Light green
Colorless
Light green
Colorless
Colorless
Yellow
Light green
Colorless
Yellow
Light yellow
Colorless
Yellow
Colorless
Colorless
Green
Colorless
Colorless
Yellow
Light yellow
Colorless
Yellow
Light yellow
Colorless
Yellow
Colorless
Desired level
Odor
None
Cresol
Slightly cresol
None
None
None
Slightly phenol
Slightly phenol
Slightly phenol
None
Slightly phenol
Slightly phenol
Slightly phenol
Slightly phenol
Slightly phenol
None
Slightly phenol
Slightly phenol
None
None
None
None
Slightly phenol
Slightly phenol
None
None
None
Mineral oil
None
Slightly phenol
Water
Temp. (°C)
9
10
8
9
9
8
10
10
8
8
9
7
10
11
10
10
11
17
12
13
12
18
18
18
19
19
20
19
20
21
PH
__
2.3
6.2
11.3
2.4
8.1
12.8
1.1
7.8
12.1
1.6
6.8
12.0
3.6
8.9
12.0
2.1
7.4
11.3
1.8
8.0
11.6
1.3
8.3
10.7
2.2
9.0
12.6
2.2
7.6
5-9
CN
(mg/1)
_
10
0.04
220
10
1.4
230
10
0.03
350
2.5
0.37
460
2.0
1.0
300
3.7
Trace
140
1.0
0.15
92
0.67
-
130
0.93
0.03
250
2.6
0.04
1 or less
T-Cr
(mg/1)
_
7.7
Trace
1.4
83
1.8
2.0
4.0
Trace
_
—
-
0.17
55
0.11
_
—
-
1.2
92
Trace
Trace
92
1.0
_
—
-
1.5
69
0.67
2 or less
Cr+6
(mg/1)
Trace
54
Trace
Trace
53
0.23
Trace
Trace
Trace
Trace
80
Trace
Trace
31
Trace
Trace
120
Trace
Trace
Trace
Trace
Trace
49
0.5
Trace
320
0.26
Trace
41
Trace
0.5 or less
S-Fe
(mg/1)
37
0.36
9.2
21
0.46
3.7
2,200
Trace
_
-
-
4.8
26
Trace
_
—
-
1.3
1,400
Trace
1.9
46
Trace
_
—
-
3.2
16
Trace
1 0 or less
Ni
(mg/1)
_
7.2
Trace
1.2
16
0.39
0.71
0.71
0.31
_
-
-
0.42
6.7
0.54
_
-
—
0.79
7.8
0.53
20
10
0.33
_
—
-
0.60
7.3
0.32
1 or less
Cu
(mg/1)
__
9.8
3.1
12
11
5.3
11
7.2
4.7
—
-
-
6.8
4.7
8.0
—
-
—
7.4
28
7.3
8.0
16
0.90
_
—
-
3.2
7.6
2.5
3 or less
Zn
(mg/1)
_
6.7
1.1
140
76
0.66
160
180
1.2
—
-
-
330
51
1.0
_
-
—
94
210
1.1
47
160
1.1
_
—
-
250
100
2.4
5 or less
Pb
(mg/1)
—
2.9
Trace
0.49
0.56
0.24
Trace
0.43
Trace
_
-
—
Trace
0.21
Trace
—
-
—
Trace
Trace
Trace
Trace
1.3
Trace
_
—
-
Trace
0.54
Trace
1 or less
Cd
(mg/1)
—
Trace
Trace
Trace
Trace
Trace
Trace
Trace
Trace
_
-
-
Trace
Trace
Trace
—
-
—
Trace
Trace
Trace
Trace
Trace
Trace
_
—
-
Trace
Trace
Trace
0.1 or less
-------
Table 2—3 Results of Treatment at Plant No. 2 (General process wastewater)
t_n
00
\, Items
DateN\v
1975
1. 8
2. -5
3. 5
4. 2
5.28
Type
Influent
Effluent
Influent
Effluent
Influent
Effluent
Influent
Effluent
Influent
Effluent
Desired level
Hue
Turbid black
Light green
Turbid grey
Light green
Red brown
Light green
Red violet
Red violet
Black
Dark green
-
Odor
Meneral oil
Hydrogen sulfide
Mineral oil
Sewage
Sewage
Sewage
Sewage
Sewage
Sewage
Hydrogen sulfide
—
Water
Temp. (°C)
9.0
9.0
10.0
10.0
10.0
10.0
12.0
13.0
19.0
19.0
—
PH
7.0
7.1
7.6
8.5
8.8
8.3
7.2
6.8
7.5
7.4
5-9
BOD
(mg/1)
810
140
240
84
580
250
320
150
301
311
300
or less
COD
(mg/1)
370
100
250
100
220
110
130
110
210
210
—
ss
(mg/1)
580
160
110
39
140
44
240
10
100
10
300
or less
Oil
(mg/1)
210
43
46
35
32
21
120
26
38
16
35
or less
-------
Unsatisfactory copper treatment is supposedly due to insufficient oxidation-
decomposition of copper cyanide, because copper in the cyanide wastewater forms
complex cyanide and as a result, copper still remains in the effluent. You may also
notice that hexa-valent chromium is found in the cyanide wastewater or cyanide is
detected in the heavy metals wastewater. This is generally attributable to, inspite of
the fact that sewage pipings in individual factories are so arranged as to separate
wastewater by its type, incomplete isolation or misoperation by factory operators. To
correct this condition which presents difficulties in proper treatment processes, we
have been keeping in touch with factory operators and providing them with necessary
information by holding guidance sessions for improved process methods and for more
strict plant management.
Treatment of general process wastewater at Plant No. 2 is generally satisfactory
with minimum variations in influent qualities in recent years.
2.3. OPERATION AND MAINTENANCE COSTS
Operation and maintenance costs including chemicals, lighting and heating
expenses, power, personnel, sludge (waste oil) disposal and pipe cleaning expenses are
totally charged to constituent enterprises. Allotment of these expenses is based upon
the quantities and qualities of wastewater discharged from individual firms.
Shown in Table 2—4 are the quantities of water treated by type of wastewater,
operation/maintenance cost, and treatment cost per one cubic meter of wastewater in
1974, as contrasted to those in 1973.
In the 1974 operation cost, because the inflation initiated by the late 1973
energy crises pushed up such expenses as power, personnel, and chemicals 30 to
100 percent, the unit cost of pickling-plating process wastewater treatment increased
to a very high level.
- 459 -
-------
Table 2—4 The volume and operation/maintenance cost of wastewater
Type of
wastewater
Miscellaneous
General process
Pickling/plating
process
Total
1973
Processed volume
264,338m3 /year
179,224
73,096
516,658
Operation/maintenance
cost
3, 774,000 yen/year
10,956,000
15,386,000
30,116,000
Average cost
per 1 m3
14.3 yen/m3
61.0
210.5
1974
Processed volume
379, 116m3 /year
272,433
45,571
697,120
Operation/maintenance
cost
8,356,000 yen/year
14,605,000
15,113,000
38,074,000
Average cost
per 1 m3
22.0 yen/m3
53.6
331.0
CTv
O
-------
As for pickling-plating process wastewater in particular, unusual increase in it is
responsible for a substantial drop in the volume of discharged drainage, as it was
described earlier, because of the depression.
2.4. PROBLEMS AND COUNTERMEASURES
2.4.1. PROBLEMS ON MANAGEMENT
(1) Treatment Capacities of Collective Pretreatment Facilities
The Processing capacity of this plant was decided on the basis of estimates
provided in reports from individual enterprises as to the quantities and qualities of
wastewater before the plant was constructed and placed into service. As a result, it is
difficult for the plant to allow constituent enterprises to increase their drainage
volumes or change the qualities of their wastewater along with development and
expansion of their business activities.
In view of our experiences with the plant, therefore, it is desirable, to design a
plant with flexibility in its capabilities to some extent to accommodate future
expansion, when a new collective pretreatment facility construction plan, will be
made.
(2) Official Determination of Wastewater Qualities
As for the determination of quality of wastewater, individual enterprise
operators are required to submit a report on it. We found however that these stated
qualities in many cases differ greatly from the fact and lack reliability. Therefore, it is
desirable that measurements be made by city officials.
(3) Expense Allotment of Operation/Maintenance Cost
Operation and maintenance costs are computed on a liquidation principle at this
plant, and this system on a year-by-year expense allotment basis has experienced such
a shortcoming: highly varying unit cost of treatment in consequence of such factors
as decreased drainage resulting from a depression and soaring management costs by
inflation, could be quite a burden to enterprise in carrying their business activities.
For this reason, it is desirable that the present system should be replaced with a
new expense allotment system based on revising service fees every two or three years
service fees offered at regular rates for two or three years.
(4) Nonfulfillment of Management Contract (delayed allotment payment, nonper-
formance of water quality reporting obligation, etc.)
Because of the fact that the City takes primary responsibility for plant operation
and maintenance, there appears a tendency that enterprise operators are less
conscious about their responsibility than before, and in fact, we have difficulty in
obtaining cooperation from some of the operators with nonperformance of
management contracts, etc.
2.4.2. TECHNICAL PROBLEMS
(1) Treatment of Wastewater Containing Oils and Fats
At this collective pretreatment plant, waste oils and fats isolated and removed by
aeration system. However, isolation performance is not satisfactory because of the
fact that various kinds of oils and fats are admitted to the facilities. To adopt a
treatment method best suited for the properties of oils in a free or emulsified state,
therefore, we believe that an individual treatment is more efficient than a collective
treatment.
(2) Pickling-Plating process Wastewater Treatment
Pickling-plating wastewater was divided into two types, that containing cyanides
and that containing heavy metals. But further seperation of the latter was impossible
for reasons of complexity and technical difficulties of piping, so that chromium
461
-------
waste water and acid/alkaline wastewater were allowed to flow in one piping system.
As a result, we faced the following problems:
1) Treatment of heavy metals is as follows: the hexa-valent chromium is reduced to
trivalent chromium first by lowering its pH value and then, by increasing its pH value,
it is separated together with other metals, and removed as hydroxides. But this
process changes not only the pH value of the chromium wastewater, but also that of
the acid/alkaline wastewater, and as a result the consumption of pH adjusting agents
such as sulfuric acid and calcium hydroxide increased. It also meant extra sludge
production and added operation cost.
2) Hexa-valent chromium reduction is conducted by automatically controlling the
feed rate of chemicals in proportion to the pH value and oxidation-reduction
potential. But because the oxidation-reduction potential is affected by iron ions,
contained substantially in the alkaline wastewater, to compensate for this condition a
reductant is added slightly more than that normally required.
3) It is a generally suggested rule that concentrated wastewater produced from
plating factories be pooled temporarily within the factories and then drained in small
quantities so that it is sufficiently diluted with usual wastewater. However, diluting
operation by individual firms isn't always performed satisfactorily.
2.4.3. THE VOLUME OF SLUDGE PRODUCED AND THEIR DISPOSAL
(1) Plant No. 1
The 1974 plant operation records show that sludge cakes (moisture content
80%) averaged 880 kilograms a day in weight.
Because pickling-plating process wastewater is treated in this plant, sludge cakes
contain such materials as heavy metals. It is necessary, therefore, that some means be
employed so that they would not ooze out of sludge cakes upon disposal. The means
applicable we have experimented or studied so far are (1) solidification with concrete,
(2) sintering, (3) melting, (4) reduction sintering, and (5) colliery reuse (bringing
them back to refineries as raw materials). As a result, considering such factors as
feasibility and prevention of further leaching, sintering method is under consideration
as the one of practical approaches today. As for this method, a flow sheet along with
part of its experimental results was summarized in the previous report. And this time,
it is presented in the following Table and Figures together with its possible
application to synthetic aggregate.
- 462 -
-------
Table 2-5 Physical characteristic of sintered sludge
Sintering
additives
Clay
Clay
Clay
Clay
Clay
Clay
Clay
Clay
Refractory
material
Refractory
material
Refractory
material
Grit-stone
Blending ratio
Plating
sludge : Clay
1 : 1
1 : 2
1 : 3
1 : 4
1 : 4
1 : 4
1 : 5
1 : 6
1 : 3
1 : 3
1 : 3
-
Sintering
temperature
(°C)
1,100
1,100
1,100
1,100
1,150
1,200
1,200
1,200
1,100
1,150
1,200
-
Sintering
time
(Minute)
60
60
60
60
60
60
60
60
60
60
60
-
Granulating
method
By machine
By machine
By machine
By machine
By machine
By machine
By hand
By hand
By machine
By machine
By hand
-
The state of sintered sludge
Half fused, Black-brown
Sinter, Black-brown
Sinter, Brown
Sinter, Light red-brown
Sinter, Brown
Sinter, Brown
Sinter, Brown
Sinter, Brown
Half sinter, Black-brown
Sinter, Black-brown
Half fused, Black-brown
Strength of crushing (kg)
Average
39
52
25
25
35
59
93
105
15
45
96
57
Min.-Max.
35- 47
44- 69
20- 30
20- 32
20- 44
49- 69
86- 98
93-113
15- 15
44- 47
60-123
44- 69
Specific
gravity
-
-
-
2.1
1.7
1.6
1.8
2.1
2.1
2.2
2.3
-
Water
absorb
(%)
-
-
-
2.7
3.0
0.03
0.82
0.67
12.9
0.84
0.47
-
-pi
Os
-------
Fig. 2—2 Solubility test of various PH in elutriate
Fig. 2—3 Sintering temperature and solubility of chromium
0.7
0.6-
Concentration
of heavy metals
in elutriate 0.5-
0.4-J
0.3'
Plating sludge : Clay =1:4
Sintering Temperature : 1,150°C
Sintering time : 60 minute
0.2-
(mg/1)
O.H
1 2
PH in elutriate
U.7-
0.6-
Concentration
of chromium
in elutriateO.5-
0.4-
0.3-
0.2-
(mg/1)
0.1-
Clay (1:4)
30 minute \
\
\
\
\
•
Clay (1 : 3) \
60 minute N. •.
Clay (1 : 4) >v \
60 minute "^.^^^^^^ >v\
Refractory material TT~"77 .X\ _
60minute ~..:_:Y_..__7?-, "" ' —
i.i'oo u'so i
»• Sintering temperature (°C)
1,200
-------
(2) Plant No. 2
The 1974 operational records show that sludge cakes (moisture content 80%)
averaged 435 kilograms a day. Because their composition is much the same as that of
domestic sewage, they are disposed as land fill, together with sludge produced from
other sewage treatment plants.
Conclusion
The example we presented in this report is a counter measure against industrial
wastewater which has been planned and practiced on the premise that industrial
wastewater from medium and small enterprise districts are allowed to flow into public
sewarage. We believe that this approach is one of the most efficient ways, at least for
the time being, and acceptable by to small and medium enterprises that can hardly
afford, technically and financially, an independent treatment.
We are generally satisfied with the operational results obtained, however, (1)
enterprise operators' sense of responsibility for their fulfillment of obligations, (2)
with the plant's capacity being inflexibly fixed, it is incapable of meeting quantitative
and qualitative changes of wastewater resulting from variations in business activities
of constituent enterprises, (3) final disposition of sludge, and (4) indiscriminately
mixed up inflow of various wastewaters are among the problems we must solve
urgently.
- 465 -
-------
CHAPTER 3. FUKASHIBA INDUSTRIAL WASTEWATER TREATMENT
PLANT IN IBARAGI PREFECTURE
3.1 General Plant Review 467
3.2 Quality and Quantity of Industry Wastewater 467
3.3 Charge 469
3.4 General Condition of Maintenance and Operation 469
3.5 The Present Sludge Disposal 469
3.6 Problems 469
- 466 -
-------
3. FUKASHIBA INDUSTRIAL WASTEWATER TREATMENT PLANT IN
IBARAGI PREFECTURE
The description of this plant was informed at the first U.S.-Japan Conference
Sewage Treatment Technology in 1971 and the general survey of the maintenance
and operation of the plant from Sept., 1971 to June, 1975 is given below.
3.1 GENERAL PLANT REVIEW
This treatment plant was designed to provide preliminary and secondary treat-
ment to the wastewater of the oil refineries and the petrochemicals existing in the
area of 1,800 ha except steel mills area in the Kashima industrial district of 2,400 ha
and the future wastewater flow is estimated about 300,000 m3 /day.
The preliminary treatment facilities include grit chambers, oil floatation tanks,
pH control tanks and the chemical coagulation and settling tanks by which B.O.D.
load for subsequent biological process is reduced and the hazardous substances for
metabolism are removed as much as possible.
The secondary treatment facilities include aeration tanks and final setting
tanks, operating as a conventional activated-sludge system for purpose of the stabili-
zation of final effluents. The secondary facilities also may be operated as a two stage
activated-sludge system if necessary, in case of the striking fluctuation of influent
quality.
In order to prevent the transpiration of odor arising from plant site, Oil floata-
tion tanks, pH-control tanks and sludge thickeners are covered with lids and the
odor is removed by a soil adsorption process or an activated carbon absorption
process.
Sludge is mechanically dewatered after thickening and then to be incinerated.
(Fig. 1)
3.2 QUALITY AND QUANTITY OF INDUSTRY WASTEWATER
Effluent of Fukashiba Wastewater Treatment Plant is discharged into the sea of
Kashima and the effluent standards are established by Ibaragi Prefectural Regula-
tions as shown in Table 1.
In order to meet the regulations, it is required that the strength of influent into
the treatment plant should not exceed approximately 200 mg/fi of COD, 250 mg/C
of suspended solid and 10 mg/£ of Hexane Solubles.
Therefore, each industry is demanded annually to report quantity and quality
of his wastewater to administrative office. The data are adjusted and effluent criteria
for each industry (agreement rules) are determined (Table 2).
Most of industries are required pre-treatment facilities to meet the criteria.
The existing pre-treatment facilities are as shown in Table 3.
The kinds of the facilities are mostly pH control tanks, sedimentation tanks
and oil separators. Some factories are required special treatment equipments such
as stripping towers to remove volatile organic matters and spray incineration equip-
ments to treat high-COD wastewater.
467
-------
REFERENCE
S. Matui, Activated Sludge Degradability of Organic Substances in the Waste-
water of the Kashima Petroleum and Petrochemical. Industrial Complex in Japan,
7th International Conference on Water Pollution Research, Paris, Sept. 9 ~ 13,
1974.
Influent
Air
_L
Air Chem leal agents
i L
f Return sludge
it
j
Execess s
c
o.
oq
o
CD
o.
CD
» Po
c"
p.
(TO
01
tanKs — tanks
1.5 h
_J ! f
vOily scum \
/' /
. ' Exhaust gas .
i »J
gulation tanks
3. Oh
Air
4
Aeration tanks
6.0 h
yelectrolytc
Sludge j
^-*-^ \
f >w ( I*1 Soil filte
1 Thickners 1 ^J
Grit chambers \ / 1
i ^~ ' Activate
^upernatant «» -^
s Dewatering
facilities
Final settling tanks
3.0 h
Chlorine
Chlorination tanks
Filtrate Cake
I Incinerators
1 ,
j (Under construction)
1 p 1
t
(Ash _ Landfill)
Effluent
Fig. 1 Process Flow of Fukashiba Wastewater Treatment Plant
- 468
-------
3.3 CHARGES
Quantity and Quality Charge System is applied for all industries discharging
into the sewers
Namely, below the agreement rules, the charge is calculated by using the
Quantity and Quality Charge formula. If the quantity and/or quality of wastewater
from any factory exceed the agreement, surcharge is levied to the wastewater below
the effluent standards of Sewerage law. And exceeding the effluent standards of the
Sewerage law, penalty is imposed. (Table 4)
Each factory is required to install flow meters, partial type or electromagnetic
type in order to measure the wastewater quantity which is the basis of the assess-
ment of the charge. Each factory also is required to install automatic pH recorders,
Toe meters etc. In addition, the continuous monitoring and the occasional quality
examinations of once to four times a month are performed to secure the effect.
3.4 GENERAL CONDITION OF MAINTENANCE AND OPERATION
The data of operations of this treatment plant in each month from January to
June, 1975 are as shown in Table 5.
Most of industries keep operating continuously around the clock and the
fluctuation of quantity and quality is little. However, the strength of chlorine ion is
approximately 3,500 mg/£ and seems to be higher than in influent into other treat-
ment plants.
The removal rate of suspended solids is high in chemical sedimentation tanks
and 80%, but those of BOD, COD and Haxane Solubles are low and 38, 15 and 33%,
respectively.
And the removal rates of them are high in final settling tanks except Haxane
Solubles and B.O.D., C.O.D. and Suspended Solids are 90, 70 and 50% removal,
respectively. But the removal rate of Haxane Solubles is 25% and it is as almost same
as in chemical sedimentation tanks. (See Table 4)
Besides, 1 mg/C of polyelectrolytes such as polyethylene aluminium chloride is
added in final settling tanks to promote sedimentation of sludge floes.
3.5 THE PRESENT SLUDGE DISPOSAL
Sludge is drawn from chemical sedimentation tanks and concentrated. De-
watering is done by Filter Press Method on a dosage of about 19 to 31% slaked lime
of dry solids. Sludge cakes are disposed by land fill, but incinerators are now under
construction and they are to be completed in Dec., 1975.
And these sludge cakes are planned to be utilized as soil enrichment agents and
fertilizer for plants in the sandy soil and the pot studies and the field plot examina-
tions of 3,000 m2 farm are provided.
The results of analysis of heavy metals contained in the sludge cakes and the
results of elution tests are as shown in Table 6 and 7 and there are no problems.
3.6 PROBLEMS
1. In the annual routine maintenance of industries BOD load and chlorine ion are
strikingly reduced, the operating control is difficult and the effluent quality
sometimes grow worse.
2. As the industrial wastewater sometimes contains high reducing materials, it is
necessary that Dissolved Oxygen in the aeration tank, is kept high level.
469
-------
Table 1 Effluent Standards for the Sea of Kashima
Constituent
1. Cadmium (Total)
2. Cyanide
3. Organic phosphide
4. Lead (Total)
5. Chromium (Total hexavalent)
6. Arsenic (Total)
7. Mercury (Total)
8. Alkyl mercury compounds
9. pH
10. C.O.D.
11. Suspended solid
12. Fecal coliforms
13. Hexane solubles (Mineral oils)
(Fats and fatty oils)
14. Phenols
15. Copper (Total)
16. Zinc (Total)
17. Iron (Dissolved)
18. Manganese (Dissolved)
19. Chromium (Total)
20. Fluoride (Total)
Concentration (mg/£)
1971
0.1
1
1
1
0.5
0.5
ND
ND
5.0-9.0
120 (100)*
60 (50)*
7(5)*
7(5)*
5
3
5
10
10
2
15
1975
0.1
1
1
1
0.5
0.5
0.005
0.005
5.8-8.6
50 (40)*
50 (40)*
3,000
3(2)*
3(2)*
5
3
5
10
10
2
5
* Daily average values are shown in parentheses.
470
-------
Table 2 Agreement Values (1977)
Factories
Tobu
District
1
2
3
4
5
6
7
8
9
10
11
12
13
(14)
15
16
17
18
19
20
Seibu
District
(21)
(22)
23
(24)
25
26
27
(28)
29
(30)
(31)
Discharge
m3/day
15,500
1,830
35
1,910
11,000
400
4,700
14,100
2,300
5,000
6,700
250
3,500
2,000
9,500
3,000
1,500
300
100
100
150
200
195
3,790
2,000
30
9,000
1,340
208
4,000
pH
5-9
5-9
6-9
5.5 - 8.5
5-9
5-9
5-9
5-9
5-9
5-9
5-9
5-9
5.8 - 8.6
6-8
5-9
6-8
5-9
6-9
5-9
5-9
6-8
6-8
6.5 - 8.6
5 -9
5-9
7.0
5-9
7.5
6-8
6-8
B.O.D
mg/£
80
250
150
249
470
90
150
160
27
270
60
50
100
250
200
60
30
300
15
350
150
50
220
300
200
100
300
10
100
25
C.O.D.
mg/C
80
300
150
242
300
70
300
160
41
200
150
150
220
250
300
60
30
250
100
300
150
50
160
150
80
100
300
20
100
20
Suspended
solid
mg/£
15
80
200
65
170
300
30
40
35
40
65
100
" 25
100
50
50
40
50
100
50
200
50
160
50
90
100
30
20
80
50
Haxane
solubles
mg/C
15
6
0
7
15
3
10
3
8
10
5
6
8
3
5
5
10
10
10
20
5
1
10
10
20
0
10
0.5
7
20
Factories
(32)
Hazaki
District
(33)
(34)
35
(36)
37
(38)
(39)
(40)
(41)
(42)
(43)
(44)
(45)
(46)
(47)
(48)
(49)
(50)
(51)
Total
Discharge
m3/day
1,000
600
720
5
180
200
710
520
21
126
90
272
1,400
640
221
249
270
810
54
1
112,727
pH
5-9
5-6
6-9
5.8 - 8.6
5.5 - 8.5
6-8
5-9
5.7 - 8.7
5.6 - 8.6
6.5 - 8.0
5.5 - 8.5
6.5 - 7.5
5-9
6-8
6-8
6.5 - 8.5
7
6.5 - 8.5
5-9
6-8
5-9
B.O.D
mg/£
20
300
250
22
50
60
10
100
90
300
70
100
300
300
68
60
22
20
5
30
186
C.O.D
mg/£
40
200
100
22
50
10
20
100
80
300
140
200
300
300
37
40
38
10
16
30
182
Suspended
solids
mg/£
20
50
10
10
20
50
50
200
250
40
50
20
20
150
18
90
70
15
10
30
57
Haxane
solubles
mg/C
7
7
5
5
5
1
10
6
0
5
7
5
10
10
1
4
4
5
0
5
9
Future industries are shown in parentheses.
-------
Table 3 Existing Pre-treatment Facilities
Factories
1
2
3
4
5
6
7
8
9
10
11
12
13
15
16
17
18
19
20
25
27
35
Total
pH control
tanks
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
17
Oil
separators
o
o
o
o
o
o
o
7
Sedimentation
tanks
o
o
o
o
o
o
o
o
o
o
o
o
12
Activated
sludge facilities
o
o
o
3
Others
Stripping tower
Stripping tower
Spray incineration equipment
- 472
-------
Table 4 Industrial Wastewater Charge System of Fukashiba Wastewater Treatment Plant
(Effective April!, 1975)
Charge = quantity charges + quality charges + surcharges + penalties
1. Quantity charges
32 yen per m3 per a day of quantity (Qe) (10 yen in 1971)
Where;
Quantity (Qe) (m3 /day) = Q (below of 3,000 m3 /day)
or
= 3,000 +0.9 (Q-3,000)
(exceed Q of 3,000 m3/day and below Q of 5,000 m3/day)
or
= 4,800 + 0.8 (Q- 5,000)
(exceed Q of 5,000 m3/day)
Q is a daily average flow (m3 /day) which is measured by a flow meter.
2. Quality charges
Quality charge per m3 per a day of "Q" is as follows:
Strength (F)
F<120
120^F<240
240 ^ F < 360
360 ^ F < 480
480 ^ F < 600
600 ^ F < 720
720 ^ F < 840
840 ^ F < 960
960 ^ F < 1080
1080 ^F< 1200
1200 ^F< 1320
Charges
1971
Yen
4
6
8
10
12
14
16
18
20
22
24
1975
Yen
20
30
40
50
60
70
80
90
100
110
120
Where;
in which B, C, S and N are BOD5 , COD, SS and Hexane Solubles in mg/£ which
are determined due to analize samples, respectively.
- 473
-------
3. Surcharges
(1) When quantity of "Q" exceeds 110% of the agreement values, 64 yen is payed
for each m3 per a day of excess quantity over the agreement values.
(2) When the strength of the wastewater exceeds 120% of the agreement values,
the following charges are payed for each m3 /day of quantity of "Q".
Surcharge (yen/m3/day)
1971 1972
3 12
6 24
10 40
When "F" based on the determined strength is below "F"
based on the agreement values or exceeds one step over it.
When "F" based on the determined strength exceed two
steps over it.
When "F" based on the determined strength exceeds three
steps over it.
4. Penalties
When the determined strengths of any constituents of wastewater exceed the
following standards, penalties of 40 yen (10 yen in 1971) per m3 per a day of
quantity is imposed for each item of violation.
Items
Temperature
PH
BODS
COD
Suspended solids
Hexane solubles
Others
Criteria
45°C
5 ^ pH ^ 9
600 mg/£
600 mg/C
600 mg/K
20
Those required by
the administrator.
- 474 -
-------
Table 5 Monthly Operation Data of Fukashiba Wastewater Treatment Plant
Month
1975
Jan.
Feb.
Mar.
Apr.
May
June
Avg.
Influent
Quantity
(m3/day)
42,800
51,800
55,400
56,300
56,500
56,100
53,200
Temperature
(°C)
22
21
22
26
30
29
25
PH
7.4
7.6
7.4
7.5
7.5
7.6
7.5
BOD
(mg/0
184
84
154
103
107
106
123
COD
(mg/0
144
145
158
132
118
127
137
Suspended
solids
(mg/0
155
190
116
115
72
63
119
Hexane
solubles
(mg/0
7
6
6
5
6
5
6
Chlorine
ion
(mg/0
2,790
2,330
2,700
4,110
4,390
3,430
3,290
Aerated oil
separators and
pH control tanks
Cu.M. ail
per Cu.M.
wastewater
4.6
3.7
3.9
3.0
3.4
3.7
3.7
Chemical coagulation tanks
Detention
time
(hr)
6.2
3.5
3.0
3.0
3.0
3.7
3.7
BOD
(mg/0
82
71
101
64
66
73
76
COD
(mg/fi)
119
128
141
107
99
104
116
Suspended
solids
(mg/fi)
14
15
33
19
40
10
24
Hexane
solubles
(mg/0
3
4
4
4
4
4
4
Month
1975
Jan.
Feb.
Mar.
Apr.
May
June
Avg.
Aeration tanks
Cu.M. air
per Cu. M.
wastewater
10.6
8.5
9.0
7.0
8.1
8.7
8.7
MLSS
(mg/0
3,750
3,870
3.970
3,250
3,710
3,350
3,650
VSS/SS
(%)
86.5
86.5
82.1
79.8
76.7
78.8
81.7
SVI
51
46
46
46
47
48
47
MLDO
(mg/0
4.3
4.7
5.8
6.0
3.8
4.1
4.7
Excess
sludge
(Ton/dry
solid/day)
0.67
0.76
0.62
0.67
1.03
1.30
0.84
Return
sludge
ratio
(%)
25
23
23
23
21
22
23
Final settling tanks
BOD
(mg/0
7
6
6
3
7
10
7
COD
(mg/0
33
35
33
30
40
36
35
Suspended
solids
(mg/£)
12
8
15
17
7
12
12
Hexane
solubles
(mg/0
2
3
3
3
3
3
3
Coagu-
lant
(mg/0
2.0
1.5
0.8
0.2
0.6
1.3
1.1
Thickener
Sludge
volume
(m3/day)
115.9
188.3
213,3
185.2
161.2
181.6
174.3
Water
contents
(%)
93.1
94.2
95.2
94.2
94.9
94.1
94.2
Dewatered sludge
Dosage
CaO
(%)
21.3
30.0
23.9
19.1
22.1
31.4
23.6
Weight of
sludge cakes
(Ton/dry
solid/day)
10.5
15.4
13.2
13.1
10.6
14.7
13.1
-------
Table 6 Heavy Metals Contained in Sludge Cakes
(mg/kg of dry solids)
Month
Cadmium
Lead
Chromium
Iron
Copper
Zinc
Manganese
Nickel
Arsenic
Mercury
1975
Jan.
4.0
220
1,048
880
1,840
195
264
208
4.0
-
Feb.
5.2
17
770
324
1,280
1,104
268
184
7.5
-
Mar.
6.4
38
920
1,100
720
1,400
198
180
1.6
-
Apr.
8.7
133
1,320
960
780
2,400
296
700
8.5
-
May
7.8
25
4,640
1,420
668
1,440
238
180
2.2
-
June
8.8
92
1,300
725
432
834
208
100
3.6
0.012
Table 7 Strength of Heavy Metals in Supernatant in Elution Tests for Sludge Cakes
Sample*
Mercury (Total)
Alkyl Mercury
Cadmium (Total)
Lead (Total)
Organic Phosphide
Chromium (Total Hexavalent)
Arsenic (Total)
Cyanide
Dry Solid**
I
ND
ND
0.01
0.05
ND
ND
ND
ND
42.6
II
ND
ND
ND
ND
ND
ND
ND
ND
42.6
III
ND
ND
ND
ND
ND
ND
ND
ND
42.6
Criteria
0.005
0.005
0.3
3
1
1.5
1.5
1
-
* Samples were prepared as follows:
Sample I: 10 g of sludge cakes was added to 90 g of water and the range of pH was
adjusted 5.8 to 6.3. Sample was mixed 6 hours and filtered with filter paper.
Sample II: As same as Sample I except pH range of 7.8 to 8.3.
Sample III: 3 g of sludge cakes was added to 97 g of water and the range of pH was
adjusted 7.8 to 8.3. Sample was mixed 6 hours and filtered with filter paper.
** Expressed in per cent.
476
-------
CHAPTER 4. DESIGN AND OPERATION OF DYING WASTE TREATMENT
FACILITY IN SABAE CITY, FUKUI PREFECTURE
4.1 Production of Coagulant "Activated Diatom Earth" from Diatomaceous
Rich in Clay and Its Features 478
4.2 Planning Design and Operation of Dying Wastes Treatment Facility
in Sabae City, Fukui Prefecture 479
477
-------
4. DESIGN AND OPERATION OF DYING WASTE TREATMENT FACILITY
IN SABAE CITY, FUKUI PREFECTURE
4.1 PRODUCTION OF COAGULANT "ACTIVATED DIATOM EARTH" FROM
DIATOMACEOUS RICH IN CLAY AND ITS FEATURES
The Noto Peninsula, lying in the north of Honshu, abounds in diatomaceous
earth containing clay and vocanic ash. Its estimated amount of reserves is said to be
as much as several thousands of millions of tons. (See Gig. 4.1)
The average composition of the diatomaceous earth produced in the Peninsula
is Si02 average 70%, A12O3 8-11%, Fe2O3 4-6%, CaO 0,5-1.4%, NgO
0.2-0.25%, and Na2O + K2O 1.5-3%, with the content of SiO2 considerably
lower as compared with ordinary one. For this reason, it has not been used as
filter agents so far.
The Ishikawa Prefectural Industrial Laboratory has investigated the commer-
cialization of diatomaceous earth buried in the ground in the Noto Peninsula for the
purpose of promoting local industries. Their efforts have turned out a coagulant
under the trade name of "Activated Diatom Earth".
The production process of this coagulant is shown in Fig. 4.2. Namely, turned-
up diatomaceous earth is dried, pulvulized, added with water and sulfuric acid,
baked in a rotary kiln at a temperature of 250 to 350°C and again pulvulized as a
final product. By baking after being added with water and sulfuric acid, the earth
has its aluminum oxide changed into aluminum sulfate and ferric oxide into ferric
sulfate, thus gaining a ability to coagulate suspended and coloidal solids. Its ability
combined with the adsorption force of diatomaceous earth, is displayed to the full
for coagulation.
The coagulant, "Activated Diatom Earth", finds itself in the treatment of some
kinds of dying waste and oil containing waste.
In Japan, the guidelines concerning the industrial effluent limitations have not
yet specified that for colour. Effluents from dying mills largely vary in pH and
contain a considerably large amount of organic substance. The most problematic
among others is their own hue and colour of the waste, which in many cases is
serving a main cause of trouble with neighbors and downstream inhabitants and
farmers.
As a consequence, the methods of reducing the colour of effluents from dying
mills have long been investigated for all that they are not specified in the guidelines.
The coagulant, "Activated Diatom Earth", is excellent in colour reduction of ef-
fluents from dying mills. Table 4.1 shows colour reduction effects and KMnO4-COD
removal in chemical coagulation of various kinds of dye solutions.
According to laboratory tests, the Coagulant is able to treat wastes of dispersion
dyes, acid dyes, naphtol dyes and vat dyes to discolour to perfection. Also, it goes
a long way with the colour reduction of direct dyes, reaction dyes and base dyes.
As regards waste of sulfide dyes, it has little or no efficacy; rather, ferrous
sulfate is more effective as a coagulant. "Activated Diatom Earth" has the optimum
pH depending on the kinds of dyestuffs at which its colour reduction performance
478
-------
can be exhinited best.
Fig. 4.3 shows the pH vs. colour reduction relationships for acid dyes (Suminol
Leveling Red 3B), base dyes (Aizen Cathilon Red K-GLH), and dispersion dyes
(Resoline Blue BR).
Another feature of the Coagulant is notable dewatering effect when applied
to sludge, and still more important is the fact that the dewatered cake can be used.
Excellent dewatering effect is attributable to diatomaceous earth in the Coagulant.
The dewatered cake has been mixed with cement and molded into artificial trees or
stones for use at parks and gardens.
Recently, a method of manufacturing filter agents from dewatered cakes has
been developed and industrialized. Since the dewatered cakes can be turned into
secondary products, the manufacturer of the Coagulant has been carried out busi-
ness taking over dewatered cakes free of charge at users' treatment plants while
suppling the Coagulant "Activated Diatom Earth".
Fig. 4.4 shows a flow sheet explaining the production process of filter agent
from sludge cakes.
4.2 PLANNING DESIGN AND OPERATION OF DYING WASTES TREATMENT
FACILITY IN SABAE CITY, FUKUI PREFECTURE
Sabae City, in Fukui Pref., developed the Eastern Industrial Estate, and has
made efforts to attract manufacturing businesses.
Now there are some dying mills in the Estate, and the water quality of the
Kurozu River which is receiving their effluents is hideously bad. The inhabitants of
downstream of the Kurozu River lodged strong protests against Sabae Municipal
Office, claiming to improve water quality.
Meanwhile, the Office planned to construct sewarage system to cover the entire
unban areas and a sewage treatment plant.
But, the plan was thought to take too much time to prevent the water pollution
of the Kurozu River. Besides, it was feared that the improvement of the secondary
effluent in hue and colour at the sewage treatment plant could hardly be expected
if the wastewater of dying mills were accepted with domestic sewage by the public
sewers.
To cope with this problem, the Sabae Municipal Office has planned to con-
struct a joint pretreatment facility where dying wastewater are treated by a chemical
sedimentation process to remove color and a part of organic substances.
While the effluent from the facility is planned to be discharged into the Kurozu
River for the time being, it will be treated again at the municipal sewage treatment
plant in future, mixed with domestic sewage. In preparation for this plan, the Public
Works Research Institute, Ministry of Construction, took a part, and discussed with
engineers of both the Municipal Office and the Dying Industry Cooperative Associa-
tion several times.
- 479 -
-------
As a result, the aforesaid coagulant, "Activated Diatom Earth", was decided
upon as the coagulation agent for the Joint Pretreatment Facility.
The reasons are as follows.
i) Of the dyestuffs used in the mills in the Sabae Eastern Industrial Estate dis-
persion dyes occupy the majority. Others, including acid dyes, naphtol dyes
and reaction dyes, are also used. From basic experiments in the past, it has
been corroborated that the coagulant "Activated Diatom Earth" is effective in
colour reduction of these dyes.
ii) Although the Activated Diatom Earth was priced at ¥25 per kg at that time,
far more expensive than other coagulants, and its dosing rate was as high as
1,000 ppm, the latter was expected to be whittled away sharply if technical
investigation has been set up.
iii) The settled sludge can be dewatered to a 70% of water content by a vacuum
filtration without filter agent. Fortunately, the manufacturer of the coagulant
"Activated Diatom Earth" has commited themselves to take over dewatered
sludge for making filter agent.
iv) From the above, it is expected that the total costs, including the cost for treat-
ment and disposal of settled sludge, will become cheaper than with other
coagulants (e.g., aluminum salts, ferrous salt, ferric salt etc.). Still another
advantage is no need of preparation of the land required for disposal of sludge.
As the coagulant, "Activated Diatom Earth", was picked up for the treatment
of waste from the dying mills, various experiments have been carried out to find the
way to minimize the dose rate of the coagulant and the way to keep stabilized
operation of the pretreatment facility. The results are as follows.
i) The waste from the dying mills are very changeable in its flow and quality
from time to time. It is therefore necessary to install an equalizing pond. The
capacity of the pond is estimated to be at least four-hour's worth of hourly
maximum waste water flow in order to keep stable operation of the joint pre-
treatment facility.
ii) If the waste of the mills is treated in the chemical sedimentation tank after
removal of their surface active agents in a foam separation tank, the dosing
rate of the coagulant can be reduced by some 30% compared with the amount
required when the waste was directly treated in a chemical sedimentation tank.
iii) Part of the coagulant "Activated Diatom Earth" to be dosed into the defoamed
waste can be replaced with an inexpensive metal salt (a mixture of aluminum
sulfate and ferric sulfate available on market at a cost of about ¥10 per kg
under the trade mark of MICS).
So long as the ratio of the "Activated Diatom Earth" to MICS is 3 : 1 or less,
there is no problem in dewatering or in making filter agent either.
iv) The optimal pH value at which the Activated Diatom Earth and MICS are to be
reacted upon the waste is in the range of pH 4.0 to 4.5.
480
-------
For this reason, sulfuric acid is required for pH control of the waste prior to
add these coagulants.
In the stage of flocculation, however, dose of lime for controlling the pH value
at 7 to 8 is better improving the floe-settling characteristics in the sedimenta-
tion tank.
Partial return of the settled sludge into the flush mixing tank is effective for
the solid/liquid separation in the sedimentation tank.
v) It is desirable to set the surface loading of the sedimentation tank at 40m3/m2.d.
or below, and the detention time at more than 2 hrs. or more.
vi) Liquid-state surface active agent separated from the foam separation tank is
brought in contact with the settled sludge for a long period, and then almost
entirely is removed as adsorbed into diatomaceous earth.
Fig. 4.5 shows a flow sheet of the joint pretreatment facility for the waste,
which has been in operation since March this year.
A part of the operation result are as shown in Table 4.2. Although the results
of the treatment of actual wastes containing various kinds of dyestuffs are worse
than those of the independent treatment of each dyestuff, but the results are still
encouraging.
- 481 -
-------
Table 4.1 COD Removals and Color Reduction Effects by Dosing Coagulant
"Activated Diatom Earth" 0.5 g/L or 1.0 g/L
~"~-\^^ Items
Dyes ^"~^--^^
(Disperse dyes) (0.1 g/C)
Resoline blue BR
Kayalon fast blue RD GGF
Kayalon polyester turg. blue
(Acid dyes) (0.1 g/C)
Lanasyn blue GL
Cidalan brill red RL
Suminol leveling red 3B
Kayanol milling red RS
(Naphtol dyes) (0.1 g/C)
TD black 10G-2S
(Direct dyes) (0.1 g/C)
Dialuminous blue GF
(Vat dyes) (0.1 g/C)
Indanthren red FBB
(Reaction dyes) (0.1 g/C)
Mikacion rubine BS
(Basic dyes) (0.1 g/G)
Aizen cathilon red GTLH
CODMn
(PPM)
80.8
46.6
54.3
77.4
75.5
41.6
24.7
65.1
25.4
54.3
39.8
65.3
0.5 g/C
CODMn
removal
(%)
67.3
63.7
70.7
91.1
69.4
73.1
88.3
84.8
76.8
82.9
51.7
40.6
Color
reduction
(%)
100
94.9
100
100
100
92.4
100
100
79.5
100
88.6
90.5
1.0 g/C
CODMn
removal
(%)
84.9
65.7
78.6
92.5
70.4
78.4
95.6
86.6
87.8
84.0
57.0
52.0
Color
reduction
(%)
100
97.2
100
100
100
97.1
100
100
100
100
88.9
95.1
- 482 -
-------
Table 4.2 A Part of Operational Data of Dying Waste Treatment Facility, Sabae City, Fukui Pref.
~~"~~~~ — ~__ c Date
i«. ^ ^s**^
Temperature (°C)
pH
Transparency (cm)
CODMn (mg/fi)
BOD (mg/2)
Sus. solids (mg/C)
400 m/z absorbance
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Inf.
Eff.
Mar. 8
12:00
35.0
33.5
7.50
6.40
17
>30
127
63.6
99
53
13.3
12.4
0.223
0.107
Mar. 8
14:00
34.5
33.0
7.50
6.42
17
>30
117
58.6
101
45
15.2
7.2
0.212
0.082
Mar. 8
16:00
35.0
33.0
7.45
6.52
16
>30
117
58.6
112
48
16.2
6.2
0.232
0.082
Mar. 10
13:30
35.0
33.0
7.50
6.67
17
>30
116
39.7
102
38
20.4
5.2
0.252
0.051
Mar. 10
15:30
35.0
33.0
7.80
6.80
17
>30
131
43.8
118
35
21.6
3.2
0.265
0.051
Mar. 13
13:00
32.0
33.0
7.68
6.82
17
>30
140
52.4
109
39
20.0
6.4
0.235
0.066
Mar. 14
11:30
35.0
34.5
7.6
6.75
16
>30
128
65.3
112
54
26.3
23.4
0.264
0.097
Mar. 14
13:30
36.0
34.5
7.73
6.85
15
>30
143
58.5
118
55
24.7
17.2
0.294
0.086
Mar. 14
15:30
34.0
34.0
7.65
6.90
12.5
>30
156
65.3
131
57
20.3
17.2
0.361
0.081
CO
-------
lizjj
Wakura &
Notoshima
Yamatoda
lizuka
lida
Layer
Depth (m)
20-60
10-20
100-400
10-60
Volume of Deposits
(x 106 mj)
340
100
4,800
25
.Kyoto
Nagoya Tokyo
saka
Fig. 4.1 Destribution of Diatom Earth Raw Materials in Noto Peninsula, Ishikawa Prefecture
484 -
-------
00
Cn
Scrubber [-
'
Line
Mixing Tank
i i
Water J '
Settling
Tank
Discharge
Coagulant
"Activated Diatom Earth"
Fig. 4.2 Manufacturing Flow Diagram of Coagulant "Activated Diatom Earth"
-------
100 r-
I 50
o
3
T3
O
u
-•—.— Acid Dyes (Suminol Leveling Reb 3B)
-o —o— Base Dyes (Aizen Cathilon Red K-GLH)
-x—x— Disperse Dyes (Resloine Blue BR)
Each Dve Solution Containes
0.25 g/£ of Dyestaff
7
PH
10
13
Fig. 4.3 Relationship between Color Reduction Effects and
pH Variation
(Coagulant "Activated Diatom Ecarth"Dose 1 g/8 _)
- 486 -
-------
-PS.
00
Sludge Hopper
Sludge Preliminary
Drying
Sludges from
Dying Waste
Treatment Facilities
Oryeir
Blower
Soda Ash
or Sodium
'Chloride
Fig. 4.4 ManuiactuTrng iRhw QSiagrain xtf Diatom Earth Filter Aid from Sludges from Dying Waste Treatment Facilities
-------
.......... J
Sulferic
Arid
,,,_ Surface Active ™
Diatom
larth
Lime
(
ush Flocculation Sedimentation „. ,
EquJization Pumps •" ™%n]c l •" Mixing Tank ~ 'lank ~.—.B*
lanK | 1
Foaming
Liq uo r
Sewer Pipes (
CO li .1 i| ,
m ....
Surface Active
Agent and
Sludge Mixing
, . . , , . T-i n I-
Dying Dying
Mill Mill
F
Thickener
Sludge Return
Supernatant
Sludge Vacuum To Diatom Earth Filter Aid
Filler *" Manufacturing Factory
Fig. 4.5 Flow Diagram of Dying Mills Waste Treatment Plant, Sabae City, Fukui Prefecture
-------
CHAPTER 5. IMPROVEMENT OF EFFLUENT QUALITY OF BISAI
DISTRICT SEWAGE TREATMENT PLANT IN AICHI
PREFECTURE
5.1 Quality of Sewage and Present State of the Sewage Treatment Plant 490
5.2 Installation of Pilot Plant 491
5.3 Installation of Pretreatment Facilities 491
5.4 Results of Laboratory and Pilot Plant Experiments 492
5.5 The Modification of Sewage Treatment Plant 494
5.6 Experiments and Studies of the Future 494
489
-------
5. IMPROVEMENT OF EFFLUENT QUALITY OF BISAI DISTRICT SEWAGE
TREATMENT PLANT IN AICHI PREFECTURE
5.1 QUALITY OF SEWAGE AND PRESENT STATE OF THE SEWAGE TREAT-
MENT PLANT
Bisai City, Inchinomiya City and Kisogawa-cho, in Aichi Pref. are alive with
one hundred and odd factories processing raw wool, dying and finishing woolen
textiles, the wastes coming from which have been treated at the Bisai District
Sewage Treatment Plant designed solely for industrial wastes treatment.
In the district, there are little factories which are equipped with a through
production system handling all the way from raw wool processing to the finishing
of woolen fabrics.
The production system is roughly classified into four processes: raw wool
processing, dying, weaving and finishing.
Of them, weaving factories do not deliver industrial wastes, but all the others
vomit wastes peculiar to respective processes.
The factories with raw wool process deliver wastes containing a great deal of
organic substance and grease. The factories with dying process discharges wastes
of residual dyes, inorganic salts (mainly sodium sulfate, soldium sulfide, etc.) and
high temperature waste water containing various kinds of surface active agents.
The factories with finishing process discharge waste water containing unrecover-
able short fibers and various surface active agents.
The quality of raw sewage running into the Bisai Sewage Treatment Plant is
shown in Table 5.1.
The raw sewage is almost neutral, but is high in temperature and contains
reducing materials and greases.
The concentration of suspended solids is not so high, but most is occupied
by short fibers which are hard to settle in the sedimentation tank.
The reducing materials are mainly composed of sulfides.
This is because in addition to sodium sulfide contained in sewage, sodium
sulfate is reduced into sulfides biochemically in the sewer pipes. The Public Works
Research Institute of the Ministry of Construction has once conducted an experi-
ment on the reduction of sulfate ions of this waste water into sulfides.
The results are as shown in Fig. 5.1. The test temperature was 25 to 30°C.
The present facilities of the Bisai District Sewage Treatment Plant include
three circular primary sedimentation tanks, three four-path rectangular aeration
tanks, nine rectangular final settling tanks, one rectangular thickener, two vacuum
filters, and a sludge incinerate A.
This sewage treatment plant is located next to the Ichinomiya Seibu Sewage
Treatment Plant, and some of the facilities are used common to both plants.
A plan view of the Bisai District Sewage Treatment Plant is shown in Fig.
5.2.
When designing this plant, the effects of short wool fibers, greases and oils,
reducing materials and various surface active agents on the process were not
evaluated thoroughly. In addition, sludge production rate and thickening rate were
490 -
-------
misevaluated.
Design capacity of the existing facilities is 70,000 m3/d. On one occasion
when the production of woolen products increased, the influent into the sewage
plant reached as large as 140,000 m3/d. At present, the influent is in the range of
80,000 to 100,000 m3/d. as a result of strong save-water campaign against
factories.
Even this, however, still surpasses the planned capacity of the plant.
While the effluent quality standard applied to this sewage treatment plant is
20 mg/1 or less in BOD, effluent of the Plant is in the range of 60 to 80 mg/1.
At the request of the Sewage Management Authority, the Water Quality Con-
trol Division of the Public Works Research Institute, Ministry of Construction, is
extending technical assistance in the improvement of effluent quality and modi-
fication of the plant facilities.
5.2 INSTALLATION OF PILOT PLANT
The request of the Sewage Management Authority for the improvement of
effluent quality and modification of facilities presupposed increasing the design
capacity up to 100,000 m3/d. and reducing BOD of effluent to 20 mg/1. without
expanding the existing site area.
In fact, the lots adjoining to the plant are hard to purchase, and the expan-
sion of the right-of-ways for the plant from the present scale is still more
difficult.
The open space available in the premises is very limited. For this reason, it
was judged difficult to add up the primary sedimentation tanks, aeration tanks
and final settling tanks.
In order to manage a proposed flow of 100,000 m3/d. with the existing
facilities, the design values should be reset as follows.
Average overflow rate of the primary sedimentation tank: 27.2 m3/m2.d.
Average aeration time: 3.85 hrs.
Detention time of sewage in the aeration tank with sludge return ratio at
30%: 2.95 hrs.
Average overflow rate of final settling tank (with sludge return ratio at 30%):
35.3 m3/m2.d.
Prior to mapping out modification plans for sewage treatment facilities, vari-
ous investigations were required, but it was difficult to utilize part of the existing
facilities for testing purposes.
Accordingly, it was decided to install a pilot plant copying the existing plant
to a scale of 1/1,000.
The pliot plant, was designed to simulate the changes of that in the full-scale
plant.
5.3 INSTALLATION OF PRETREATMENT FACILITIES
In view of the limited capacity of the sewage treatment plant and the need
to improve the effluent quality without expanding its facilities, it was also needed
to request the factories to moderate their waste discharge into the sewer.
- 491 -
-------
The requests were as follows:
i) Each factory to make every effort to limit its daily discharge not to exceed
the total factory discharge of 79,000 m3/d. set by the Sewage Management
Authority.
ii) Each raw wool processing factory to install a pretreatment facility to remove
high concentration of n-hexane extracts contained in its effluent to 30 mg/1.
or less.
iii) Each of those raw wool processing and dying factories which discharge waste
water of 40°C or higher to install a heat exchanger to recover heat in order
to decrease wastewater temperature before discharge into the sewer to lower
than 40° C.
iv) Each chromic dye-using factory to install a pretreatment facility to remove
chromium and limit the chromium content in effluent before discharge to
lower than 0.5 mg/1.
If possible, such chromium removal facility should be used common to all
chromic dye-using factories.
v) Each finishing factory to install a micro screen of 4 x 4 mm meshes in order
to reduce the discharge of short wool fibers.
vi) Those factories which discharge waste water of more that 1,000 m3/d to
install a storage tank for the purpose of equalizing effluent.
At present, the equalization of effluent is undertaken by two storage tanks
(7,000 m3 and 5,000 m3) and sewer pipes (8,000 m3) (20,000 m3 in total).
If the factory with more than I,000m3/d of waste water is equipped with a
storage tank the influent of the sewage treatment plant will be kept almost
constant all the day.
5.4 RESULTS OF LABORATORY AND PILOT PLANT EXPERIMENTS
Both laboratory study and pilot plant experiments are still in progress. The
findings obtained so far are as follows:
i) Chemical flocculation to remove reducing materials, oils and greases and
short wool fibers in the primary sedimentation tank has been studied both
on a laboratory scale and pilot plant scale.
It is found that the use of aluminum sulfate and lime in combination is most
effective.
The required dose is 200 to 300 mg/1. of A12(SO4)3 and 100 to 120 mg/1.
of Ca(OH)2. In this process, the oils and greases in the waste water can be
removed 70 to 80% in terms of n-hexane extracts. Also, the reducing mate-
rials can be removed more than 60% in terms of iodine demands. In addi-
tion, short wool fibers can be removed efficiently. The sludge volume devel-
oped from the process is 170 to 220 mg/1 in terms of suspended solids, and
the under flow concentration of the sedimentation tank is less than 0.5%
According to the cylinder test, the thickening of this sludge is very poor;
even with a 24 hrs thickening, the reduction of the sludge volume is only
492
-------
about 50%.
ii) As against the overflow rate of 27.2 m3/m2 -d. (max. 31.7 m3/m2 .d.), the
plain sedimentation gave suspended solids removal of approx. 80 mg/1 or some
47%.
The withdrawn sludge concentration was approx. 0.5%.
According to the sludge thickening test by cylinder, the sludge volume was
reduced to some one-third in about 18 hrs of thickening time.
iii) Effluent of plain sedimentation was treated by activated sludge process with an
average aeration time of 3.83 hrs.
In this case, the ratio of sludge return from the final settling tank was 25%.
The concentration of return sludge was very high enough to maintain MLSS
in the aeration tank at level of 3,000 to 4,000 mg/1.
As a result, effluent BOD was 16 to 20 mg/1 with MLSS above 3,000 mg/1,
BOD loading lower than 0.376 kg/kg. MLSS.d. and with the air supply more
than 9 times the influent.
In this case, SVI of the activated sludge was approx. 100. DO in the aeration
tank was able to be kept at 2 mg/1 all the time.
The results of molecular graduation of influent and effluent by Sephadex
G15 are shown in Fige. 5.3 and 5.4.
iv) Sometimes, the influent carries wastes with a odor of naphtol. In such a
case, DO in the aeration tank is reduced almost naught, and BOD of effluent
becomes higher than 20 mg/1.
It remains uncertain what air flow rate can keep DO concentration in the
aeration tank above 0.5 mg/1.
Molecular graducation by Sephadex G15 of influent and effluent in these cases
is as shown in Figs. 5.5 and 5.6.
v) The influent shown in Fig. 5.5 is richer in low molecular materials of frac-
tion number 28 or above than that shown in Fig. 5.3.
High molecular weight materials are less compared with Fig. 5.3.
On the other hand, the influent shown in Fig. 5.3 is rich in high molecular
weight materials of more than 1,500 in molecular weight and in colloidal
materials.
vi) Fig. 5.4 indicates that organic removal was significant in the process.
The influent shown in Fig. 5.3 contained a great amount of high molecular
weight meterials and colloidal materials, but did not affect to the treatment
at all.
The peak of the ultea-violet absorbance curve for the effluent shown in Fig.
5.6 was shifted toward the lower molecualr weight side as compared with the
effluent in Fig. 5.4. This is inferred to be ascribable to the fact that the
dissolved oxygen might have been in deficit in the activated sludge process.
vii) Plastic diffuser were used for the pilot plant. The oxygen absorption efficiency
of this plastic diffuser was 6.1% when the water depth was 2.0 m above the
diffuser.
- 493
-------
The disc diffuser now in operation creates some 3% of oxygen absorption
efficiency when the water depth is 3 m. This low performance is further
aggravated by the colgging of the pores with grease and short wool fibers
contained in the sewage.
It is therefore urgently needed to replace the diffuser with one which is not
affected by grease and short wool fibers and with which high oxygen absorp-
tion efficiency can be attained.
viii) The oxygen consumption rate, kr. of the activated sludge was measured at
four points in the aeration tank. The results were 37.0, 28.2, 20.9 and 15.9
mgO2 /gr/hr.
The selection of diffuser and determination of air supply rate are to be made
according to the above results, and in consideration of the case where sewage
of low oxygen absorption efficiency can run into the system on some occa-
sions.
ix) There were lots of scum and floating matters on the surface of the final
Settler.
The scum increased BOD and suspended solids of the effluent.
5.5 THE MODIFICATION OF SEWAGE TREATMENT PLANT
i) The primary sedimentation tank is to be modified to carry out plain sedi-
mentation.
The sludge collector is to be modified to have an increased collecting speed
in order to shorten the detention time of sludge in the tank.
The primary sedimentation tank is to be equipped with a scum collector. In
order to improve the sludge withdrawal, the valves and pipeline are to be
modified.
ii) The diffusers are to be replaced with a more efficient ones.
Additional air blowers are to be installed to make up air supply.
iii) The final settling tank is to be equipped with a scum collector. Also, an air lift
is to be provided for easier withdrawal of sludge.
iv) The sludge thickener is to be expanded in order to allow more than 18 hrs
of thickneing time.
It is also to be provided with a scum collector in the thickener.
5.6 EXPERIMENTS AND STUDIES OF THE FUTURE
i) Preaeration will be carried out for the purpose of increasing the grease re-
moval by promoting dewatering of emulsified greases and oils and of increas-
ing the removal of reducing materials.
The detention time of the preaeration tank should be within 20 min.
ii) Experiments for the determination of the diffuser characteristics to be
applied in the aeration tank will be conducted. The experiments should cover
determination of the oxygen transfer efficiency and the protection of the
diffuser from clogging by grease.
- 494 -
-------
iii) Study will be made to provide measures to maintain the level of dissolved
oxygen constant in the aeration tank even when sewage of low oxygen demand
iv) Dewatering of thickened sludge will be studied on presupposition that the
sludge be incinerated, and the equipment will be selected so to meet.
v) Odor control at preaeration tank and sludge treatment facilities will be
studied.
- 495 -
-------
Table 5.1 Influent Quality of Bisai District Sewage Treatment Plant,
Aichi Pref. (February to March 1975)
~~—~^__^^ Range
Items
Sewage temperature
Transparency
or average
^^^
CO
(cm)
pH
Suspended solids
CODMn
BOD
Iodine demands
n-Hexane extracts
Total chremium
(mg/C)
(mg/C)
(mg/C)
(mg/C)
(mg/C)
(mg/C)
Range
21.0 ~ 31.5
2.2 ~ 5.7
6.6 ~ 8.4
50 -202
62.9 ~110.2
89.8 -291.6
8.3 ~ 46.4
7.6 -128.0
0.21~ 1.10
Average
27.5
3.6
7.3
129.0
88.7
181.2
28.2
70.3
0.59
- 496 -
-------
-P"
UD
•a
>,
X
00
§
3
00
70-
£,60-
-------
Chlorine Contact Tank
ooo
) | Sludge Incinerator
o
-X
.*!
"^ ' \
Sludge ! .Thickener '
' \ )
.. / \ /
Sludge Dematering
Building
I I I I
Final Settling Tank
T3 S
j2 2
cd GO
If
° I
m £,
IT
^
r
>»
^v
Ae
^
ation
J
Tank
^
f
J
•N
V
>
V
r
>»
•N
L
y
Fig. 5.2 Plan of the Bisai District Sewage Treatment Plant, Aichi Prefecture
-------
2.0
Sample Filtrated 0.45/j Membrene
Sample Concentrated 10 times of
Above Filtrated Sewage
Fig. 5.3 Molecular Graduations of Influent, Ultra-Violet Absorbance, and Carbon and
Nitrogen Compound Variations
- 499 -
-------
< 0.5-
= £
O GO
-0 O
--
<-> z
50-
o
h- £
Sample Filtrated 0.45/u
Membrane
Sample Concentrated 10 times
of Above Filtrated Sewage
10
40
Fraction
Numbers
P5XXXSI Total Carbon
TOC 1C
Total Nitrogen
Fig. 5.4 Molecular Graduation of Effluent, Ultra-Violet Absorbance, and Carbon and
Nitrogen Compound Variations
- 500
-------
1.0-
Sample Filtrated 0.45^
Membrane
Sample Concentrated 10 times
of Above Filtrated Sewage
Fig. 5.5 Molecular Graduation of Effluent, Ultra-Violet Absorbance, and Carbon and
Nitrogen Compound Variations
- 501 -
-------
Sample Filtrated 0.45^
Membrane
Sample Concentrated 10 times
of Above Filtrated Sewage
40 Fraction
Numbers
Fig. 5.6 Molecular Graduation of Effluent, Ultra-Violet Absorbance, and Carbon and
Nitrogen Compound Variations
- 502 -
-------
AGENDA
CINCINNATI, OHIO
ROBERT A. TAFT LABORATORY
Thursday, October 23
8:30 am F. M. Middleton - Official Opening of Conference
Dr. T. Kubo - Response
8:45 am L. W. Lefke - Welcome to Cincinnati
8:55 am F. M. Middleton - Agenda Approval
9:00 am R. C. Brenner - Updated Status of Oxygen-Activated
Sludge Wastewater Treatment
9:45 am Break
10:00 am B. V. Salotto - Current Research Related to Heat
Conditioning of Wastewater
Sludge
10:30 am R. A. Olexsey - EPA's Research Program in Sewage
Sludge Combustion
11:00 am R. I. Field - Urban Stormwater Management and
Technology in the United
States - An Overview
12:00 noon Lunch
1:30 pm J. J. Westrick - Activated Carbon for Municipal
Wastewater Treatment
2:15 pm J. Ciancia - New Industrial Wastewater Separation
Processes Developed Under the
EPA Research Programs
3:00 pm Break
3:15 pm J. F. Roesler - Status of Instrumentation and
Automation for Control of
Wastewater Treatment Plants
4:00 pm J. N. English - Research Required to Establish
Confidence in the Potable
Reuse of Wastewater
4:30 pm J. J. Convery - Summary and Comments
5:00 pm F. M. Middleton - Closing and Announcements
- 503 -
-------
UPDATED STATUS OF OXYGEN-ACTIVATED SLUDGE WASTEWATER TREATMENT
R. C. Brenner
U. S. Environmental Protection Agency
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
ABSTRACT
The oxygen-activated sludge wastewater treatment process continues to enjoy vigorous
growth in the United States. Recently, new markets for oxygenation technology have emerged
in Japan, Europe, and the greater North American continent. As of June 1976, 50 oxygen-
ation installations were in operation. An additional 66 oxygen plants were under construc-
tion and designs were in progress for another 41. The combined design flow of these 157
known commitments to the use of oxygen exceeds 5.8 bgd (254 cu m/sec). Approximately
one-half of the operating installations are industrial wastewater applications.
The Union Carbide Corporation, from its vantage point of first entry into the field,
has collected the major share of the oxygen market to date with its covered reactor UNOX
system. The only other available covered reactor oxygenation system is sold by Air
Products and Chemicals, Inc. under the trade name OASES. An open reactor oxygen-activated
sludge option (MAROX) employing ultra fine bubble rotating active diffusers has recently
been developed by the FMC Corporation. A large-scale demonstration project evaluating
this MAROX system is currently underway at Metropolitan Denver's main wastewater treatment
plant. The project is a joint effort of the local government, FMC, and the federal
government.
INTRODUCTION
In the past eight years, the use of
oxygen gas in the activated sludge process
has evolved from a level of primarily aca-
demic interest to a point of broad appli-
cation and implementation. A large and
rapidly growing number of oxygen-activated
sludge plants are in operation in North
America and Japan. Several plants will soon
be operational in Europe. Included among
the operating facilities are installations
treating process wastewaters from six major
industrial categories. By 1980, it is pro-
jected that construction will be completed
on approximately 150 oxygen systems with a
combined hydraulic capacity between 5 and 6
bgd (219 to 263 cu m/sec).
Beginning with the initial research
project conducted by Union Carbide at
Batavia, New York, in 1968 and 1969 (1),
the development and refinement of oxygen-
ation technology has been more rapid than
normally associated with wastewater treat-
ment processes. Design engineers today can
select from several oxygen dissolution con-
cepts including both covered and open reac-
tor alternatives. The covered reactor UNOX
and OASES systems are available with either
surface aerators or submerged turbines.
The surface aerator option has become the
standard covered reactor design except in
cases where unusually deep tanks are speci-
fied. FMC markets two versions of its open
reactor MAROX system, one utilizing rotating
active diffusers (RAD's), the other fixed
active diffusers (FAD's). At this time, the
second generation RAD design appears to be
a significant cost-effective improvement
compared to the original FAD design. In the
near future, a fourth company, AIRCO
Cryoplants, is expected to start actively
competing in the oxygenation field. AIRCO
has named its latest development the F30
system, which stands for forced free fall
504
-------
oxygenation. The principal components of
the F30 system are a gas-tight drop-in
concrete hood, an axial flow pump, a nozzle,
and an oxygen enriched waterfall zone.
The purposes of this paper are three-
fold:
1. To provide an updated status report
on the number and type of oxygen-activated
sludge facilities in operation, under con-
struction, and being designed.
2. To describe in detail the latest
EPA supported oxygenation research and
demonstration project, an evaluation of the
RAD version of the open reactor MAROX system
being carried out at the Metropolitan Denver,
Colorado Sewage Treatment Plant.
3. To summarize design, operating,
and performance information for several
on-line oxygen wastewater treatment systems.
STATUS REPORT JUNE 1976
A complete listing of the 50 oxygen-
activated plants that were in operation as
of June 1976 is presented in Appendix A.
The 66 oxygenation plants under construc-
tion on the same date are listed in Appen-
dix B. An additional 41 oxygenation plants
were in various stages of design during
June 1976; these plants are listed in Appen-
dix C. Besides these 157 known commitments
to oxygen use, proposals have been made to
numerous other potential municipal and
industrial customers by the several oxygen
proprietary firms. These potential cus-
tomers are not included in Appendix C be-
cause final decisions on process selection
have not yet been made. It should be under-
stood from the above comments that the
status of oxygen implementation is in a
state of flux and that the three lists given
in the Appendices will be out of date within
several months.
All three appendices provide design
flow and oxygen supply data (where known)
for each plant location listed, as well as
identifying the wastewater application.
Multiple oxygen process applications, such
as carbonaceous organics removal plus nit-
rification, aerobic digestion, ozonation,
etc., are also noted where applicable. In
addition, Appendices A and B include infor-
mation on the oxygen dissolution and oxygen
supply systems selected. This latter
information is not given in Appendix C
because these plants have either not yet
been bid or litigation has delayed awarding
of contracts to specific oxygen system
suppliers.
Perusal of Appendix C reveals that no
industrial wastewater applications are shown
in the "plants being designed" list. This
omission is not intended to indicate that
no industrial plants were in the design
phase as of June 1976, but rather that the
identity of such plants is confidential
proprietary information until after equip-
ment purchase contracts are awarded.
Data on the number of plants, design
flows, and oxygen supply capacities have
been extracted from Appendices A, B, and C
and condensed in Table 1. The same infor-
mation is presented in Table 2 for United
States oxygen plants only. These two tables
indicate that as of June 1976 only about 12
percent of the firm planned oxygen design
flow capacity was actually completed and
in operation. On-line capacity is expected
to increase 7-8 times, however, in the next
4-5 years. Approximately 25 percent of the
oxygen installations included in the Table 1
totals are treating or will treat industrial
process wastewaters. Excluding the Japanese
plants for which oxygen supply data were
unavailable to the writer, the design oxygen
supply capacity averages 3.07 tons/mil gal
of design flow (7.4 x 10 metric ton/cu m)
for the industrial applications compared to
1.34 tons/mil gal of design flow (3.2 x 10~4
metric ton/cu m) for the municipal appli-
cations .
A breakdown of the 157 known operating
and planned oxygen installations by country
is given in Table 3, Eighty-five percent
of these installations are or will be lo-
cated in the United States and 11 percent
in Japan. The remaining 4 percent are
divided among seven other countries with
one plant each.
The detailed information provided in
Appendices A and B on oxygen dissolution
and oxygen generation systems is summarized
in Tables 4 and 5, respectively. The
dominance of Union Carbide in the oxygen
dissolution market to date is evident: of
the 116 oxygen installations that were
operational or under construction in June
1976, a UNOX system was selected for 87
percent. In most but not all cases, the
vendor supplying the oxygen dissolution
equipment was also awarded the oxygen
505
-------
TABLE 1. WORLDWIDE OXYGEN PLANT STATUS JUNE 1976
Parameter
No. of Plants
Municipal
Industrial
Total
Design Flow (mgd)*
Municipal
Industrial
Total
02 Supply Capacity^ (tons/day)*
Municipal
Industrial
Total
Operating
Plants
26
24
50
584.5
135.5
720.0
477.7
389
866.7
Plants
Under
Construction
49
17
66
2302
191.5
3126.5
462.5
3589.0
Plants
Being
Designed
41
41
2647.3
3794
3794
Total
116
41
157
5533.8
327.0
5860.8
7398.2
851.5
8249.7
*1 mgd =•= 0.044 cu m/sec
tOxygen supply figures shown do not include data for Japanese plants; these data were
unavailable to the writer.
+1 ton/day = 0.907 metric ton/day
TABLE 2. USA OXYGEN PLANT STATUS - JUNE 1976
Parameter
No. of Plants
Municipal
Industrial
Total
Design Flow (mgd)*
Municipal
Industrial
Total
02 Supply Capacity (tons/day) t
Municipal
Industrial
Total
Operating
Plants
21
14
35
570.3
94.3
664.6
467.7
389
856,7
Plants
Under
Construction
46
11
57
2172.8
166.8
2944.5
383.8
3328.3
Plants
Being
Designed
41
41
2647.3
3794
3794
Total
108
25
133
5390.4
261.1
7206.2
772.8
7979.0
*1 mgd = 0.044 cu m/sec
tl ton/day = 0.907 metric ton/day
TABLE 3. BREAKDOWN OF OXYGEN PLANTS BY COUNTRY - JUNE 1976
Country
1.
2.
3.
4.
5.
6.
7.
8.
9.
USA
Japan
Canada
Mexico
England
Germany
Denmark
Switzerland
Belgium
Operating
35
14
1
No. of Plants
Under
Construction
57
3
1
1
1
1
1
1
Being
Designed Total
41 133
17
1
1
1
1
1
1
1
Total
50
66
41
157
506
-------
supply system contract, The preponderance
of surface aerators over submerged turbines
in covered reactor systems is illustrated
in Table 4 and is attributed to the lower
overall costs and maintenance requirements
of the aerator option. Surface aerators are
being or will be used in 93 percent of the
covered reactor systems with specified
dissolution equipment, submerged turbines in
6 percent, and a combination of both in one
system. Plants employing submerged tur-
bines have deep aeration tanks, typically
greater than 20 ft (6.1 m), and tend to be
larger than 100 mgd (4.4 cu m/sec) in size.
Conversely, the average design flow of the
103 surface aerator systems is only about
18 mgd (0.8 cu m/sec).
Cryogenic oxygen gas generators are
sold by several firms in the United States,
whereas Union Carbide is the only known USA
manufacturer of pressure swing adsorption
(PSA) oxygen gas generators. The break-
even range determined by Union Carbide for
these two oxygen supply systems is approx-
imately 20-25 tons/day (18-23 metric tons/
day). Below this range, it is more cost
effective to use PSA generators; above this
range, cryogenic generators are more cost
effective. Other manufacturers have
developed mini-cryogenic oxygen generators
to compete for the lower tonnage plants,
On-site cryogenic or PSA gas generation
was selected for 80 percent of the 99
oxygen-activated sludge plants with defined
methods of oxygen supply, as of June 1976.
The average capacities for these 79 supply
systems are 92 tons/day (83 metric tons/day)
for the cryogenic units and 16,2 tons/day
(14.8 metric tons/day) for the PSA units.
Pipeline transport of off-site gen-
erated oxygen gas to an oxygenation waste-
water treatment plant can be an economical
choice of oxygen supply if the logistics
are reasonable and if the off-site facility
(e.g., a steel production plant) has extra
generation capacity. This method of oxygen
supply accounts for 9 percent of the defined
supply systems and 6 percent of the June
1976 "operating" and "under construction"
capacity, On-site storage and vaporization of
trucked-in liquid oxygen, because of its
high unit cost, is generally confined to
requirements of 5 tons/day (4,5 metric tons/
day), or less. The oxygen consumption of
the 11 such systems documented in Table 5 is
expected to average 2.9 tons/day (2.6 metric
tons/day); this amounts to only 0.7 percent
of the defined oxygen supply capacity.
TABLE 4, SUMMARY OF OXYGEN DISSOLUTION SYSTEM VENDORS,
TYPES, AND DESIGN FLOWS - JUNE 1976
Parameter
Operating
Plants
Plants
Under
Construction
Total
02 Dissolution System Vendor (No.)
UNOX - Covered Reactor44
OASES Covered Reactor 4
MAROX Open Reactor 2
Total 50
02 Dissolution System Type (No.)
Covered - Surface Aerators44
Covered - Submerged Turbines 4
Covered - Combination of Aerators and Turbines 0
Open Rotating Active Diffusers 2
Open Fixed Active Diffusers 0
Total 50
02 Dissolution System Design Flow (mgd)*
Covered - Surface Aerators 286
Covered - Submerged Turbines 423.8
Covered - Combination of Aerators and Turbines 0
Open - Rotating Active Diffusers 10.2
Open - Fixed Active Diffusers 0
Total 720.0
57
6
3
66
59
3
It
2
1
66
1526
345
600f
21.5
1
2493.5
101
10
5_
116
103
7
1
4
1_
116
*1 mgd * 0.044 cu m/sec
tThe oxygen dissolution system for Detroit's second-phase construction consists of sub-
merged turbines in the lead stages and surface aerators in the rear stages.
507
-------
TABLE 5. SUMMARY OF OXYGEN SUPPLY SYSTEM
TYPES AND CAPACITIES - JUNE 1976
Parameter
Operating
Plants
Plants
Under
Construction
Total
02 Supply System Type (No.)
On-Site Cryogenic Generation
On-Site PSA Generation
On-Site Liquid Storage and Vaporization
Off-Site Pipeline Transport
Unknown*
Total
7
15
9
5
14
50
31
26
2
4
3
66
38
41
11
9
17
116
02 Supply System Capacity (tons/day) t
On-Site Cryogenic Generation
On-Site PSA Generation
On-Site Liquid Storage and Vaporization
Off-Site Pipeline Transport
Total
407
254
27.8
178
866.8
3086.8
413.5
4.5
84.2
3589.0
3493.8
667.5
32.3
262.2
4455.8
*Data unavailable for Japanese oxygen supply systems
tl ton/day * 0.907 metric ton/day
Oxygen plants treating or scheduled to
treat industrial wastewaters are broken down
by industrial application in Table 6. Eight
major categories are represented in the
"operating" and "under construction" clas-
sifications. The pulp and paper industry
leads the list: nearly one-half of the total
plants and over three-fourths of the total
design flow. The next most frequent users
to date have been the petrochemical and
chemicals industries. Inasmuch as oxygena-
tion technology is well suited to satisfying
the high oxygen demand associated with many
industrial wastewaters, continuing rapid
growth in the oxygen industrial market is
anticipated for years to come.
DESCRIPTION OF SECOND GENERATION FMC
OPEN REACTOR OXYGEN SYSTEM (MAROX)
The covered reactor oxygen system,
including both the surface aerator and sub-
merged turbine alternatives,, has been de-
scribed previously in the Proceedings of the
Second U.S.-Japan Conference on Sewage
Treatment Technology (2) and elsewhere (3).
A description of the first generation fixed
active diffuser (FAD) version of the open
reactor oxygenation system was also provided
in these documents. It is not deemed nec-
essary to reiterate those descriptions here;
however, certain characteristics of the
covered reactor systems and the FAD open
TABLE 6. BREAKDOWN OF OXYGEN PLANTS
BY INDUSTRIAL APPLICATION
Operating
Plants
Industrial
Application
1. Chemicals
2. Dyestuffs
3. Food Processing
4. Petrochemical
5. Pharmaceutical
6. Pulp § Paper
7. Steel
8. Synthetic Rubber
No.
of
Plants
4
0
1
5
2
11
0
1
Design
Flow
(mgd) *
10.9
0
1
9.9
1.7
111.2
0
0.8
Plants
Under
Construction
No.
of
Plants
3
1
1
3
0
8
1
0
Design
Flow
(mgd) *
15.2
3.1
1.8
15.0
0
142.7
13.7
0
Total
No.
of
Plants
7
1
2
8
2
19
1
1
Design
Flow
(mgd) *
26.1
3.1
2.8
24.9
1.7
253.9
13.7
0.8
Total
24
135.5
17
191.5
41
327.2
•1 mgd = 0.044 cu m/sec
508
-------
reactor system are compared with the second
generation open reactor FMC option, de-
scribed below.
A section view of the key element (the
rotating active diffuser (RAD)) of the second
generation FMC system is shown in Figure 1.
As indicated, the basic RAD consists of a
7-ft (2.1-m) diameter submerged rotating
plate mounted to the bottom of a 6 5/8-inch
(16.8-cm) diameter hollow shaft approximate-
ly 3 ft (0.9 m) above the aeration tank
floor. A 7 1/2-inch (19.1-cm) wide ceramic
diffusion medium is inserted into preformed
openings top and bottom around the periphery
of the plate, forming two circular diffusion
bands parallel to the outer tapered edge.
Approximate 28-inch (71-cm) diameter radial
impellers mounted to the top and bottom of
the plate provide essential mixing of oxygen,
substrate, and biomass. An optional sur-
face impeller can be installed to aid in
foam breakup, if desired. The relatively
low design rotational velocity of 75-85 rpm
is achieved with a constant speed motor and
an appropriate gear reduction unit. The
composite submerged assembly is illustrated
in a cutaway perspective view in Figure 2.
INTERFACE
FMC—[-OTHERS
STANDARD
RAILING
FLEXIBLE HOSE
ROTATING GAS SEAL
II MOTOR
A * *
h-GAS SUPPLY LINE
STANCHION
GEAR REDUCER =
WALKWAY AND TOP OF COPING
WATER LEVEL
SURFACE IMPELLER
6 5/8" DIA.
HOLLOW SHAFT
MIXING IMPELLERS
DIFFUSION
MEDIUM
7'-0" DIA.
TANK FLOOR^
. ° D. D i . j O a i
f> . • ° •• O '. t> . t> - P ' _£. • - * . ° .
Figure 1. Section view of rotating active diffuser and drive assembly.
(Printed, with modifications, through the courtesy of the FMC Corporation.)
509
-------
MIXING
IMPELLERS
(TOP AND BOTTOM)
DIFFUSION
MEDIUM
(TOP AND BOTTOM)
Figure 2. Perspective view of
submerged rotating active diffuser
showing gas flow and bubble formation.
(Reprinted, with modifications, through
the courtesy of the FMC Corporation.)(4)
A functional flow diagram for a typical
MAROX system employing RAD's for oxygen
transfer is presented in Figure 3. The
primary oxygen supply (shown as a cryogenic
generator) is supplemented by a liquid
oxygen reserve supply and accompanying
vaporizer. With a cryogenic generator,
unlike a PSA generator, losses occurring
from the liquid oxygen backup tank, either
through usage or evaporation, can be re-
plenished directly from the primary supply
source.
Oxygen gas from the supply system is
pressurized to 30 psig (2.1 kgf/sq cm) with
a separate compressor (not shown in Figure
3) and fed down through the hollow RAD
shafts and then radially outward through
small ducts located inside the diffuser
plate to the ceramic medium. As oxygen gas
emerges from the upper and lower diffusion
bands, the rotational shear created by cen-
trifugal force forms ultra small bubbles in
the 50-100 micron range which do not co-
alesce as they move outward and pass over
the outside tapered edge of the diffuser
plate. The primary function of the tapered
edge is to prevent turbulence which could
induce bubble coalescence. The resulting
micron bubble dispersion resembles a mist
from which oxygen is rapidly and efficiently
dissolved in the mixed liquor. The oxygen
transfer rate obtained with bubbles of this
minute size is sufficiently high to report-
edly sustain an oxygen utilization effi-
ciency greater than 90 percent in conven-
tional depth uncovered aeration tanks (4).
A dissolved oxygen (DO) feedback sys-
tem is used to control the oxygen feed rate
to the RAD's. The control system, consist-
OVERFLOW WEIR
DIFFUSERS
A
AERATION TANK FLOOR
Figure 3. Functions flow diagram of typical MAROX system
employing rotating active diffusers. (Reprinted, with
modifications, through the courtesy of the FMC Corporation.) (4)
510
-------
ing of one or more DO probes, analyzers,
control valves, and electronic controllers,
automatically maintains the mixed liquor
DO concentration at a predetermined set-
point, within the tolerance range of the
equipment. A one-module control system,
i.e., one probe, analyzer, control valve,
and controller each, is shown controlling
the oxygen feed rate to both diffusers in
Figure 3. In a longer tank requiring 10-20
RAD's, multiple control modules would be
necessary with each module controlling the
feed rate to a bank of 3-5 diffusers.
The lack of necessity for a tank cover
enables FMC to avoid the sealing problems
with its MAROX systems that must be con-
sidered with the covered reactor systems.
MAROX systems do not utilize internal
staging baffles. Although most covered re-
actor systems designed to date have included
staging baffles, they are not essential.
Both the open and covered reactor alterna-
tives can be designed compatibly with any
of the commonly used activated sludge flow
regimes. Covered reactor systems are,
however, more naturally adapted to the con-
ventional plug flow regime. Where conven-
tional activated sludge treatment is the
flow regime of choice, the staged con-
figuration more nearly approximates ideal
plug flow and, other factors being equal,
would be expected to deliver an effluent
with a slightly lower soluble BOD than an
unstaged system.
Other features distinguishing the
open and covered reactor approaches from
each other are:
1. The type of oxygen feed con-
trol systems. As mentioned previously.
MAROX utilizes a DO based oxygen feed con-
trol system. The covered reactor systems
control oxygen feed rate by maintaining
a predetermined gas pressure in the first-
stage head space.
2. Freeboard requirements. Cov-
ered reactors require more freeboard than
open reactors. The greater freeboard is
needed to provide adequate gas space for
the umbrella throw pattern of the surface
aerators normally employed in covered re-
actor designs. Utilization of submerged
oxygen dissolution equipment obviates the
necessity for as large a freeboard with
the MAROX approach.
3. Carbon dioxide buildup. It
is anticipated that MAROX systems will be
less subject to carbon dioxide buildup and
attendant pH depression than UNOX and OASES
systems due to the absence of a tank cover.
The degree to which cell respiration by-
products are vented from the open MAROX
reactor will depend primarily on surface
turbulence levels and the thickness of foam
buildup, if any, on the aerator surface.
4. Hydrocarbon buildup. The
absence of a tank cover virtually elimin-
ates the possibility of accumulating an
explosive concentration of volatile hydro-
carbons over the aerator liquid surface.
It is assumed, therefore, that safety pre-
cautionary measures could be less extensive
with MAROX systems than with covered reactor
systems.
5. Oxygen feed pressure to the
oxygen dissolution systems. The nominal
pressure of oxygen gas leaving cryogenic
and PSA generators is 3-5 psig (0.21-0.35
kgf/sq cm). This is more than sufficient
to satisfy line and entrance losses to a
UNOX or OASES reactor and maintain a pres-
sure of 1-3 inches (2.5-7.5 cm) of water
in the first-stage vapor space. Con-
versely, head loss through either of the
MAROX diffusers is substantial, requiring
an additional compressor to pressurize
generator output to 30 psig (2.1 kgf/sq cm).
In comparing FMC's two open reactor
options, the several inherent advantages
of the RAD system over the FAD system are
expected to produce a pronounced preference
for the RAD alternative. These advantages
include:
- no requirement for prescreening
of aerator influent,
no requirement for pumping mixed
liquor through the diffusers to create the
necessary shear to produce micron size bub-
bles,
reduced oxygen dissolution
power requirements,
- simplified installation, and
less maintenance.
511
-------
METRO DENVER DEMONSTRATION PROJECT
In June 1975, the U.S. Environmental
Protection Agency (EPA) awarded a $200,000
demonstration grant to Metropolitan Denver
(Colorado) Sewage Disposal District No. 1
to evaluate the MAROX system. The remain-
der of the estimated total project cost
of $605,000 is being shared by the District
and FMC. The EPA Grant No. is S803910.
The evaluation is being conducted in
a segment of Metro Denver's existing air-
activated sludge plant. The plant's sec-
ondary system consists of thirty-six 210-ft
(64-m) long, 670,000-gal (2536-cu m) aera-
tion bays and twelve 130-ft (39.6-m) dia-
meter clarifiers. Each of the clarifiers
is mated with three aeration bays operated
in series to form 12 parallel secondary
trains. Several of the bays have on occa-
sion been utilized for aerobic stabilization
of waste activated sludge. Sludge is re-
cycled separately for each quadrant of the
plant, i.e., settled sludge from the three
clarifiers in any given quadrant is trans-
ferred to a common collection well from
where it is returned for distribution among
the three aeration trains in that quadrant.
Approximately two-thirds of the aver-
age influent flow of 140 mgd (6.1 cu m/sec)
receives primary sedimentation before it
reaches the plant; the other third is pri-
mary settled on site. A new 72-mgd (3.2
cu m/sec) UNOX facility, scheduled to
become operational in the fall of 1976,
will divert a significant fraction of the
primary effluent flow from the existing
overloaded air-activated sludge plant.
Prior to grant award, it was mutually
decided that the large-scale MAROX system
to be evaluated by the District would
employ RAD's rather than the older FAD's
used in previous pilot-scale studies at
Metro Denver and on a previous EPA sup-
ported grant project at the Englewood,
Colorado, wastewater treatment plant (2)(3).
Thirteen RAD's were installed in the first
bay of aeration train No. 11 of the existing
Metro air plant. The other two bays of
this train have been taken out of service
for the duration of the project. Required
hydraulic modifications included the in-
stallation of a pipe to transfer mixed
liquor from the end of the first bay to
clarifier No. 11 and separate return and
waste sludge lines and pumps. The latter
step was taken to isolate MAROX sludge
from the recycle sludge of the two remain-
ing operating air trains (Nos. 7 and 9)
of the plant's northeast quadrant. A
liquid.oxygen storage tank and vaporizer
were installed adjacent to the converted
oxygen test bay. During the first portion
of the evaluation, trucked-in liquid oxy-
gen is being used for oxygen supply.
However, the two 40-ton/day (36.3-metric
ton/day) cryogenic oxygen gas generators
that will serve the new Metro Denver UNOX
treatment plant will have excess capacity
initially. For economic reasons, consid-
eration is being given to utilizing the
excess capacity for supplying oxygen to
the MAROX demonstration project once shake-
down of the cryogenic units is complete.
If this action is taken, a compressor will
have to be installed to raise generator
output pressure to a level compatible with
RAD operation. A process schematic of the
Metro Denver MAROX test system is given
in Figure 4. Dimensioned plan and section
views are shown in Figure 5.
As indicated in Figure 5, the RAD's
are located on 21-ft (6.4-m) centers. Six
of the 13 diffusers were installed in sets
of two in the first quarter of the tank
where oxygen demand is greatest. The
remaining seven diffusers are located in
tandem on the longitudinal center line of
the aeration tank. The first 11 RAD's are
driven by 10-hp (7.5-kw) motors and rotate
after gear reduction at 85 rpm. The motors
for the last two RAD's are 7 1/2 hp-(5.6-
kw) units. The rotational speeds of the
twelfth and thirteenth RAD's are 80 and
76 rpm, respectively. The oxygen dis-
solution capability of the diffusers is
rated at 1500 Ib/day (680 kg/day) each in
the District's wastewater for a total
system capacity of 9.75 tons/day (8.85
metric tons/day). Previous proprietary
tests indicated these diffusers can be
operated up to 33 percent over their
rated capacity without significantly af-
fecting oxygen transfer efficiency. On
this basis, assuming an average BODs re-
moval of 140 mg/1 and an oxygen require-
ment of 1.3 Ib 02/lb BODs removed (1.3
kg/kg), the maximum sustained flow which
can be handled by this oxygen dissolution
equipment is roughly 17 mgd (0.74 cu m/sec).
Three DO probes and control systems are
employed to control oxygen feed to the Metro
Denver test bay. One system controls the
feed rate to the first six diffusers, the
second to the middle four diffusers, and the
512
-------
INFLUENT
WASTEWATER
Figure 4. Process schematic of Metro Denver MAROX test system.
(Reprinted through the courtesy of the FMC Corporation.) (5)
>- -<
^LIQUID OXYGEN SUPPLY
-CONTROL VALVE
IFf^
J-'1'!"
OXYGEN SUPPLY TO INDIVIDUAL DIFFUSERS
DISSOLVED OXYGEN PROBE
TOTAL THREE FURNISHED
MOUNTED ON THE BASIN HAND RAIL
r*A
) (
)- -i
^
ROTATING DIFFUSERS-
Tl
}~ 15-0"
T ^
3UAL SPACES AT2l'-0"= IB9'-0^
TOTAL 13 DIFFUSERS
- 2IO'-O" LENGTH-
>-».A
INFLUENT
FROM PRIMARY
SETTLING
TANK
RETURN SLUDGE FROM SECONDARY CLARIFjER
LIST OF EQUIPMENT FURNISHED BY FMC
• BRIDGES, BRIOGt SUPPORTS, HAND RAILS
• DIFFUSERS WITH DRIVE UNITS
• LIQUID OXYGEN STORAGE TANK
• VAPORIZER
• OXYGEN SUPPLY
• CONTROL PANEL (NOT SHOWN)
• CONTROL INSTRUMENTATION [NOT SHOWN)
SECTION A-A
Figure 5. Dimensioned plan and section views of Metro Denver MAROX test system.
(Reprinted through the courtesy of the FMC Corporation.) (5)
513
-------
third to the last three diffusers. Based
on mutual agreement, an initial DO setpoint
of 3.0 mg/1 was selected. During the first
month following startup, the oxygen control
equipment exhibited a variance range of
±0.7 mg/1 from the desired setpoint.
The RAD's and RAD drives are supported
from metal bridges which span the aeration
test bay, as illustrated in Figure 5. The
bridges in turn are supported by stanchions
(not shown in Figure 5) running to the tank
floor. The bridges were tied with minimal
defacing into the side walls of the test
bay to prevent lateral movement. Following
delivery of the key components of the
oxygen supply and dissolution systems to
the project site, the entire installation
including piping modifications was com-
pleted in six weeks. Due in part to the
short period in which its system components
can be installed and the minimum structural
modifications required, the upgrading of
existing air-activated sludge plants as
exemplified by the Metro Denver demonstra-
tion project is expected to become an im-
portant MAROX application.
From the section view of Figure 5, it
can be seen that surface impellers were not
provided with the RAD's. The District has
experienced a float buildup of relatively
high solids concentration (2-3 percent TSS)
on the mixed liquor surface. Under other
circumstances and with the proper removal
equipment, this float would constitute a
potentially attractive source from which
to waste excess sludge at a substantially
higher solids concentration than available
in secondary clarifier underflow. Since
the District is not equipped to waste
sludge in this manner, the presence of
the float represents an operational and
esthetic liability. To overcome this
problem, installation of an aeration test
bay overflow weir, similar to the one
shown in Figure 3, is under consideration.
The weir would replace the present sub-
merged orifice through which the mixed
liquor now exits the aeration bay. Utili-
zation of an overflow weir would promote
continuous transfer of floated solids to
the secondary clarifier before they could
accumulate on the liquid surface. Another
float avoidance technique being evaluated
is the use of one or more down draft pro-
peller pumps to recirculate floated solids
back into the mixed liquor. For long term
operation, the overflow weir option is be-
lieved to be a more positive and cost-
effective method than either surface
impellers on the RAD shifts or down draft
propeller pumps. For expediency on this
finite length demonstration project, how-
ever, the down draft propeller pump
technique may be selected, even though
it would add 6-12 percent to oxygen dis-
solution system power requirements. A
decision will be made in time for imple-
mentation during the month of September
1976.
The major objective of the project
from the District's standpoint is to
determine the technical feasibility and
attendant costs of converting its existing
air-activated sludge plant to a higher
capacity (i.e., two to three times higher)
open reactor, oxygen-activated sludge sys-
tem. If successful, the District could
potentially avert another major secondary
plant expansion for the foreseeable future,
with the exception of the additional clar-
ifiers which would be needed to handle
increases in influent flow. EPA's primary
project objectives are: (1) to demonstrate
at a representative field scale an altern-
ative oxygenation concept which has been
extensively and successfully evaluated at
pilot scale and (2) to define reliable
design criteria, operating conditions and
costs, and performance expectation for a
system embodying that concept for use by
the engineering community.
Equipment installation and piping mod-
ifications were completed in early May 1976.
The remainder of the month was devoted to
facility shakedown and adjustments. June
was utilized as a process start-up period
for training operators and refining a data
logging and retrival system. The evalu-
ation program was initiated on July 1, 1976,
and will continue for 10 months til]
April 30, 1977. The five planned phases
and corresponding dates of the evaluation
program are described below:
Phase I, July 1976,
Constant flow @ 2 mgd (0.39 cu m/sec);
warm wastewater temperatures; one
clarifier only in use
Phase II, August-September 1976,
Diurnally varied flow @ 7 to 14 mgd
(0.31 to 0.61 cu m/sec); warm waste-
water temperatures; second clarifier
available, if necessary
Phase III, October 1976,
Constant flow @ 2 mgd (0.34 cu m/sec);
cool wastewater temperatures; one
clarifier only in use
514
-------
Phase IV, November-December 1976,
Diurnally varied flow @ 7 to 14 mgd
(0.31 to 0.61 cu m/sec); cool waste-
water temperatures; second clarifier
available, if necessary
Phase V, January-April 1977,
Constant flow increased in increments
to failure; cool wastewater tempera-
tures; two clarifiers in use
Anticipated operating conditions are
not documented here for each planned phase
because of the variability that will be
introduced by diurnal flow. However, for
reference purposes, baseline operating con-
ditions are summarized below for the 9-mgd
(0.4 cu m/sec) constant flow phases, as-
suming an average primary effluent BODs
concentration of 140 mg/1, a sludge return
rate equal to 40 percent of the influent
flow rate, and average mixed liquor sus-
pended solids (MLSS) and mixed liquor
volatile suspended solids (MLVSS) concen-
trations of 4000 and 3200 mg/1, respec-
tively:
Nominal Aeration Time (based on Q)
= 1.79 hr
Actual Aeration Time (based on Q + R)
= 1.28 hr
Food to Microorganism (F/M) Loading
= 0.59 Ib BOD5 applied/day/Ib MLVSS
under aeration (0.59 kg/day/kg)
Volumetric Organic Loading
= 117 Ib BOD5 applied/day/1000 cu ft
aerator volume (1503 kg/day/cu m)
Secondary Clarifier Overflow Rate
(based on total surface area)
= 678 gpd/sq ft (27.6 cu m/day/sq m)
Secondary Clarifier Overflow Rate
(based on useful surface area; ex-
cludes effluent launder area)
= 746 gpd/sq ft (30.4 cu m/day/sq m)
Secondary Clarifier Mass Loading
(based on floor area)
= 31.7 Ib MLSS/day/sq ft
(155 kg/day/sq m)
Average operating and performance data
for the startup month of June 1976 are pre-
sented in Tabl^7. The average secondary
effluent suspendecKsolids (TSS) concen-
tration of 30 mg/1 is^only marginally
acceptable. Daily log sheets reveal, how-
ever, that this effluent parameter exhibited
a steadily decreasing concentration trend
throughout the 30-day period as operators
'became more familiar with system operation
and sludge inventory management. Effluent
TSS for the first 12 days of July averaged
20 mg/1, a 33 percent decrease from June.
The seven-day/week data collection program
depicted in Table 7 will be used, along with
several additional tests not conducted in
the startup month, throughout the planned
evaluation studies. One of these additional
tests will be the periodic determination of
oxygen utilization efficiency. This will
be accomplished with the aid of a 6-ft x 6-
ft (1.8-m x 1.8-m) floating dome. Off gases
from a 36-sq ft (3.34-sq m) area of tank
surface will be collected inside the dome
and funneled through a gas flow and com-
position monitoring station. The tent will
be moved to different sections of the
aeration test bay to arrive at a composite
or average utilization efficiency.
Caution should be exercised in extrap-
olating the sludge production and oxygen
supply rates given in Table 7. These values
are for one month of operation only and were
generated immediately following a period of
operator familiarization with a new process.
A better perspective of the relationship of
these important parameters to organic load-
ing will be gained from an evaluation of all
the data at the end of the project.
CASE HISTORIES
Operating and performance data and case
history summaries are presented below for 11
oxygen-activated sludge plants. Ten of the
plants utilize UNOX oxygenation systems, the
other an OASES system. All 11 plants are
documented in the listing of operating fa-
cilities provided in Appendix A.
The case histories were selected to
illustrate a variety of process applications,
system component configurations, and plant
sizes. Eight of the selected plants treat
municipal wastewaters; three are strictly
industrial applications. Several of the
municipal installations receive a signifi-
cant fraction of their incoming loads from
industrial sources. The reactor designs
for these plants represent a variety of
configurations including both rectangular-
stage systems and systems incorporating cir-
cular and arcuate stages within larger self-
contained circular tanks.
In addition to operating and perform-
ance data, a flow diagram is presented for
each case history along with pertinent
background information, where known, lead-
ing to the selection of an oxygen system.
515
-------
TABLE 7. JUNE 1976 AVERAGE OPERATING AND PERFORMANCE
DATA FOR METRO DENVER OPEN REACTOR OXYGENATION PROJECT
Influent Flow ..9.5 mgd (0.42 cu m/sec)
Return Sludge Flow., -3.8 mgd (0.17 cu m/sec)
Return Sludge Flow/Influent Flow 40%
Pri. Eff. BODs 126 mg/1
Sec. Eff. BOD5 19 mg/1
BODs Removed Across Secondary 85%
Pri. Eff. TOG 87 mg/1
Sec. Eff. TOC 29 mg/1
TOG Removed Across Secondary 67%
Pri. Eff. TSS 88 mg/1
Sec. Eff. TSS 30 mg/1
TSS Removed Across Secondary 66%
MLSS 3050 mg/1
MLVSS 2610 mg/1 (volatile fraction = 85 . 6%)
Mixed Liquor DO 2.7 mg/1
Mixed Liquor Temperature 20°C
Return Sludge TSS 10,970 mg/1
Return Sludge VSS 9120 mg/1 (volatile fraction - 83.1%)
Depth to Clarifier Sludge Blanket 7.5 ft (2.3 m)
Nominal Aeration Time (based on Q) 1.69 hr
Actual Aeration Time (based on Q + R) 1.21 hr
F/M Loading ....0.68 Ib BODs applied/day/lb MLVSS under
aeration (0.68 kg/day kg)
Volumetric Organic Loading .....Ill Ib BODs applied/day/1000 cu ft aerator
volume (1432 kg/day/cu m)
Secondary Clarifier Overflow Rate
(based on total surface area) 716 gpd/sq ft (29.2 cu m/day/sq m)
Secondary Clarifier Overflow Rate
(based on useful surface area;
excludes effluent launder area) 787 gpd/sq ft (32 cu m/day/sq m)
Secondary Clarifier Mass Loading
(based on floor area) 25.5 Ib MLSS/day/sq ft (124 kg/day/sq m)
Waste Activated Sludge Mass 5060 Ib/day (2295 kg/day)
Sludge Production Rate (based on
waste sludge TSS only) 0.60 Ib TSS/lb BODs removed (0.60 kg/kg)
Sludge Production Rate (based on
waste sludge § sec. eff. TSS) 0.88 Ib TSS/lb BODs removed (0.88 kg/kg)
Sludge Retention Time (SRT).. ..2.3 Ib MLSS under aeration/(Ib waste sludge
TSS + sec. eff. TSS lost)/day =2.3 days
RAD Power Draw . 109 hp (81 kw)
Oxygen Supplied 11,363 Ib 02/day (5154 kg/day)
Oxygen Supply Rate (based on load) 1.14 Ib 02/lb BOD5 applied (1.14 kg/kg)
Oxygen Supply Rate (based on removal) 1.34 Ib 02/lb 6005 removed (1.34 kg/kg)
Noteworthy start-up, operating, and main-
tenance difficulties encountered are dis-
cussed. Secondary system components and
any flow routing peculiarities are described
briefly. Data available to the writer for
summarization herein varied from one month's
results at several plants to more than two
years' results at another location.
Decatur, Illinois (UNOX)
Prior to the recent addition of a UNOX
system, the Sanitary District of Decatur's
wastewater treatment plant consisted of two
rectangular primary clarifiers, six Imhoff
tanks, 12 air aeration bays, three secon-
dary clarifiers, two trickling filters, one
primary anaerobic digester, one secondary
digester, one supernatant holding tank, and
tertiary and sludge lagoons. Six of the
existing air aeration bays are of 1935
vintage; the other six are larger and were
installed in 1965.
In July 1975, the liquid portion of a
comprehensive plant upgrading program was
516
-------
completed. The heart of this upgrading
effort was the conversion of three of the
1965 air aeration bays to oxygen service.
The walls of these bays were extended up-
wards 4 ft (1.2 m) and the bays covered
to provide the needed vapor space to sat-
isfactorily control oxygen feed and inter-
stage gas transport. The remaining nine
air aeration bays have been combined into
an integrated system to operate in parallel
with the oxygen unit in either the conven-
tional mode or as a modified contact sta-
bilization process. The nine bays are
shown schematically in the flow diagram of
Figure 6 as two tanks, one representing
the six older 1935 bays, the other the
three newer 1965 bays.
Coinciding with the modifications to
implement oxygen-activated sludge treat-
ment, three new primary clarifiers and four
new secondary clarifiers were constructed.
Two of the three new primaries have 100-ft
(30.5-m) diameters and are in use contin-
uously. The third new primary has a dia-
meter of 130 ft (39.6 m) and is only used
during severe storms with the overflow
discharged directly to the receiving river
following chlorination. The new secondary
clarifiers are mated with the UNOX system,
the old secondaries with the revamped air
aeration facilities. The diameter and
side water depth (SWD) of the new second-
aries are 100 ft (30.5 m) and 12.5 ft (3.8
m), respectively. The old trickling fil-
ters (not shown in Figure 6) were abandoned
in September 1975. The old rectangular
primary clarifiers (also not shown in
Figure 6) have been placed on standby ser-
vice.
A program to upgrade the sludge han-
dling portion of the plant is currently
underway and is scheduled for completion in
December 1976. The old supernatant holding
tank and old secondary digester are being
converted to heated primary anaerobic di-
gesters to join the one existing primary
digester. When completed, supernatant will
be returned directly to the plant headworks.
Five of the existing six Imhoff tanks
(omitted from Figure 6) are being outfitted
with covers to operate as non-heated sec-
ondary digesters. The sixth Imhoff tank
will remain uncovered and serve as a holding
tank for both oxygen and air waste activated
sludges prior to separate thickening in a
new concentrator. Waste sludge is presently
returned to the primaries for thickening
before digestion.
Each of the three oxygen trains is
divided into four stages. The overall
dimensions of the oxygen reactor are 148
ft long x 77 ft wide x 14 ft SWD (45 m x
23.5 m x 4.3 m) with a freeboard of 4 ft
(1.2 m). The oxygen dissolution system con-
sists of surface aerators combined with
bottom propellers for additional mixing.
The PSA oxygen generation unit has a design
output capacity of 17 tons/day (15.4 metric
tons/day). The storage capacity of the
backup liquid oxygen supply tank is 43 tons
(39 metric tons).
On the average, 55 to 60 percent of
the incoming organic load is from indus-
trial sources, primarily corn and soybean
processing. Some of the industrial con-
tributors have their own treatment facil-
ities which discharge effluent into the
Decatur sewer system. The particular mix-
ture of domestic, industrial, and partially
treated wastes received at the Decatur
plant is conducive to the formation of a
poor settling filamentous sludge. Fila-
mentous conditions have been a historical
problem with and continue to seriously
plague the air aerated trains. According
to plant personnel, filamentous infestation
is much less prevalent in the oxygen sludge,
but is present in sufficient quantities
that a substantially less dense settled
sludge is produced than predicted. Even so,
oxygen clarifier underflow concentrations
range from 70-100 percent higher than
comparable data for settled air sludge.
The inability to thicken oxygen sludge
during clarification to the degree planned
has resulted in lower MLSS and higher F/M
operating conditions than designed for.
These conditions have apparently not
adversely affected effluent quality which
remained good throughout the first year of
operation, .as indicated in Table 8. The
somewhat higher effluent suspended solids
value shown for February corresponded to
an average influent flow equal to 115 per-
cent of design. The effluent data given
in Table 8 represented UNOX system efflu-
ent quality prior to mixing with air sys-
tem effluent or subsequent treatment in the
tertiary lagoons.
Recent communication with the assist-
ant plant manager elicited the following
observations on his part:
1. The oxygen system has con-
sistently outperformed the air system by
517
-------
TABLE 8. OPERATING AND PERFORMANCE DATA
FOR DECATUR, ILLINOIS OXYGEN SYSTEM
Operation
Parameter
Influent Flow (mgd)*
Aeration Detention Time, Q (hr)
F/M Loading
(kg BOD5/day/kg MLVSS)
Secondary Clarifier Overflow
Rate (gpd/sq ft)t
MLSS (mg/1)
Return Sludge TSS (%)
Reactor Influent BOD 5 (mg/1)
TSS (mg/1)
Secondary Effluent BOD5 (mg/1)
TSS (mg/1)
Design
17.7
1.6
0.62
560
5500
1.9
188
138
20
25
Aug.
1975
14.4
1.97
1.10
456
2700
0.55
157
139
9
22
Feb.
1976
20.4
1.39
1.47
645
3300
0.93
129
138
15
36
July
1976
14.1
2.01
0.91
446
2600
0.87
98
99
10
20
*1 mgd = 0.044 cu m/sec
tl gpd/sq ft = 0.041 cu m/day/sq m
a wide margin, despite treating approxi-
mately twice as much flow in a substantial-
ly smaller reactor volume.
2. The oxygen system has exhib-
ited excellent day-to-day process reliabil-
ity and is generally capable of recovering
from slug loading upsets within 24 hours.
3. Oxygen dissolution and supply
systems require more operator attention than
conventional air processes, primarily be-
cause of the greater amount of instrument-
ation involved. Several equipment mal-
functions to date have been beyond the
ability of the plant operating staff to
correct and have required attention on the
part of the vendor.
4. Several PSA compressor out-
ages were experienced during early oper-
ations due to an improper inner cooling
system. The cooling system was eventually
redesigned and rebuilt and is now per-
forming satisfactorily.
The upgrading modifications imple-
mented at Decatur have resulted in an in-
crease in plant capacity from 20 mgd (0.9
cu m/sec) to 25 mgd (1.1 cu m/sec) and a
substantial improvement in total plant
performance. Two-thirds of the upgraded
25 mgd (1.1 cu m/sec) capacity is assigned
to the new oxygen system, one-third to the
existing air system.
Detroit (#1), Michigan (UNOX)
Initial planning for expansion to sec-
ondary treatment at Detroit called for the
installation of a 1200 mgd (52.6 cu m/sec)
air-activated sludge facility to be com-
pleted over a four-phase construction period
spanning approximately ten years. Two 150-
mgd (6.6-cu m/sec) air train modules were
to be installed during each construction
phase, yielding an eventual total of eight
modules.
Coinciding with' Detroit's planning
program, the use of oxygen in the activated
sludge process was being investigated in a
federally supported research project at
Batavia, New York (1) (2)(3). Based pri-
marily on promising results emanating from
this project, Detroit became interested in
utilizing oxygen in its own treatment sit-
uation. The City made a decision in 1969 to
modify its first construction phase to
include one 150-mgd (6.6-cu m/sec) air
module and one 300-mgd (13.1-cu m/sec) UNOX
module. The reactor tanks for both systems
were designed with identical outside dimen-
sions, meaning that the aeration detention
time of the oxygen system was to be one-half
of that of the air system. The high-rate
treatment potential of the oxygenation
process was of utmost importance to the
City because of a serious land shortage
problem.
518
-------
PSA GENERATOR 1 7TPD
u
LOX
STOR
AGE
BAR SCREEN
INFLUENT
PRIMARY CLARIFIERS
TO LANDFILL x
I WASTE SLUDGE ^
BYPASS PEAK FLOWS
^ T
AIR REACTOR
UNOX REACTOR
SUPER-
NATANT
HOLDING
TANK
RECYCLE
SLUDGE
ANAEROBIC
DIGESTERS (2)
AIR CLARIFIERS ITO LANDFILL
WASTE SLUDGE
Figure 6. Flow diagram of Decatur, Illinois wastewater treatment plant.
(Printed, with modifications, through the courtesy of the Union Carbide Corporation.)
519
-------
The construction contract awarded by
the City included process guarantee require-
ments for the UNOX system in the areas of
effluent quality, power consumption, and
oxygen consumption. The efficacy of the
UNOX and air systems was to be compared in
parallel test runs. Depending on the re-
sults of the tests, the two systems were
designed such that the 150-mgd (6.6-cu m/
sec) air train could be readily converted
to a 300-mgd (13.1-cu m/sec) oxygen train
by the addition of a tank cover, submerged
turbine/sparger units for oxygen dissolu-
tion, and three more secondary clarifiers.
With this possibility in mind, the com-
pressors which continuously recirculate
gas through the submerged turbine/sparger
units were double sized to handle 600 mgd
(26.3 cu m/sec). If the test results
indicated superior performance by the air
train, the City retained the option by
virtue of the identical reactor designs of
switching the higher capacity oxygen system
to a 150-mgd (6.6-cu m/sec) air system by
removing the tank cover and substituting
air draft tubes for the oxygen dissolution
equipment.
For the test runs, six secondary
clarifiers were to be mated with the oxygen
reactor, three with the air reactor. The
clarifiers are of unique design with a
diameter of 200 ft (61 m), a SWD of 16 ft
(4.9 m), an extremely high average surface
overflow rate of 1600 gpd/sq ft (65 cu m/
day/sq m), rapid sludge removal suction
pipes, and a peripheral-feed rim-takeoff
flow configuration. Although the oxygen
module has been in operation since August
1974, the writer is not aware of the
publication of any officially conducted
comparative test results on the two sys-
tems to date. Normal start-up problems
and delays in getting nine clarifiers com-
pleted reportedly contributed to the delay
in parallel testing. Whether official test
data are eventually published or not, it
would appear that Detroit is committed to
oxygen use. Two new 300-mgd (13.1-cu m/
sec') oxygen modules are now under construc-
tion as part of the City's second-phase
construction program. The second-phase
oxygen systems will utilize OASES equip-
ment. If Detroit decides at a future date
to convert the air train installed under
first-phase construction to oxygen service,
the City will have realized its ultimate
goal of 1200 mgd (52.6 cu m/sec) of treat-
ment capacity with four reactor modules
instead of eight. A flow diagram for the
first-phase air and oxygen modules is given
in Figure 7.
The large 30-ft (9.1-m) reactor SWD
employed in first-phase construction neces-
sitated the use of the submerged turbine
oxygen dissolution alternative. The over-
all dimensions of the UNOX reactor are
600 ft long x 140 ft wide x 33 ft deep
(183 m x 42.7 m x 10.1 m). Oxygen gas is
supplied to the UNOX system by a 180-ton/
day (163-metric ton/day) cryogenic gener-
ator. A 900-ton (816-metric ton) liquid
oxygen storage tank provides backup.
Following start-up, it became
evident that sufficient detail had not been
given to the design of the submerged tur-
bine assemblies. Propeller failures and
gear box problems resulted from inadequate
materials selection and fabrication. Re-
design and partial equipment replacement
were necessary to correct the deficiencies.
Another problem encountered by the plant
staff was obtaining a tight seal at the
joints between the outside edges of the
reactor cover and the reactor walls.
Despite experiments with several different
sealants and sealing procedures, this situ-
ation was only marginally rectified at the
time of this writing. Cryogenic generator
performance has been very satisfactory with
minimal downtime. During the first 550
days of operation, less than 2.5 percent
scheduled and 0.4 percent unscheduled out-
ages were experienced.
Average operating and performance data
for the UNOX system are documented in Table
9 for September 1975 and a 1-1/2 month per-
iod in the spring of 1976. These data were
generated at constant influent flow. Impo-
sition of diurnal flow variations on the
UNOX system will be postponed until the
remainder of the secondary treatment trains
under construction come on-line. It is
obvious that reactor influent BOD5 con-
centrations have been considerably lower
than expected. The weaker strength primary
effluent is partially attributable to the
recent initiation of iron addition to the
primary clarifiers for phosphorus removal.
Two major operational problems have
surfaced with the secondary clarifiers.
One involves achieving proper peripheral
influent distribution to avoid short cir-
cuiting of mixed liquor solids directly up
to the rim-takeoff weirs. The other is the
extreme difficulty encountered in getting
settled sludge to thicken to acceptable
concentrations prior to removal from the
520
-------
TABLE 9. OPERATING AND PERFORMANCE DATA
FOR DETROIT (#1), MICHIGAN OXYGEN SYSTEM
Operation
Parameter
Influent Flow (mgd)*
Aeration Detention Time, Q (hr)
F/M Loading
(kg BOD5/day/kg MLVSS)
Secondary Clarified Overflow
Rate (gpd/sq ft)t
MLSS (mg/1)
Return Sludge TSS (%)
Reactor Influent BOD5 (mg/1)
TSS (mg/1)
Secondary Effluent BOD5 (mg/1)
TSS (mg/1)
Design
300
1.42
0.47
1600
6250
--
140
150
25
30
1975
302
1.41
0.58
1611
2340
0.66
44
105
6
9
March 29 -
May 9, 1976
299
1.42
1.05
1595
2750
0.85
101
240
17
31
*1 mgd = 0.044 cu m/sec
tl gpd/sq ft = 0.041 cu m/day/sq m
clarifiers. The impact of the thin settled
sludge situation is evident in Table 9 in
low MLSS levels and high F/M loadings.
The Detroit oxygen sludge does have good
thickening properties as exemplified by the
ability to separately thicken waste sludge
to 4 percent solids in 24 hours without
chemical conditioners. In the writer's
opinion, secondary clarifier operational
difficulties will continue as long as the
clarifiers are subjected to the inordin-
ately high overflow rates currently in use.
Fairfax County, Virginia (OASES)
The Westgate plant is one of four
municipal wastewater treatment plants
operated by Fairfax County, Virginia. This
plant, constructed in 1954, was originally
designed to remove 50 percent of the BODs
loading from a design flow of 8 mgd (0.35
cu m/sec).
Basic features of the original Westgate
facility in sequence consisted of bar screen-
ing, comminution, primary clarification,
once-through aeration, secondary clarifi-
cation, and chlorination. Sludge recycle
pumps were not provided. The main treat-
ment basin was divided into two parallel
tanks. Each tank housed primary clarifi-
cation, aeration and secondary clarification
sections separated only by baffles. Scrap-
er chains passed along the entire floor
length through all the sections of the
tanks. The apparent purpose of the scrapers
was to move biological solids and grit
settling out in the secondary clarification
zones back to the primary clarification
zones where they could be removed from the
system. Although the original plant was
not intended to function as an activated
sludge system, it is highly likely that
some settled solids were resuspended in the
aeration zones during scraping transport,
thus maintaining a small active biomass
population in those zones. The decision
to forego installation of the additional
clarifier appurtenances, sludge recycle
equipment, and piping which would have
permitted operation in a conventional acti-
vated sludge mode was necessitated by fund-
ing limitations at the time of initial
construction.
From 1954 to 1965, plant influent
flows increased gradually from 8 mgd (0.35
cu m/sec) to slightly less than 10 mgd
(0.44 cu m/sec). BOD and suspended solids
removals during this period averaged approxi-
mately 50 and 65 percent, respectively. By
1970 with plant flows having further in-
creased to approximately 11 mgd (0.48 cu
m/sec, BOD removal had dropped to 45 per-
cent and suspended solids removal to 55
percent. In 1970, faced with the choice of
either upgrading BOD removal efficiency to
80 percent or having a building moratorium
placed on the area served by the plant, the
County submitted a report to the State of
Virginia recommending that interim upgrading
steps be applied at Westgate pending com-
521
-------
CRYOGENIC GENERATOR 180 TPD
LOX
STORAGE
PICKLE LIQUOR
FROM INDUSTRY
•«
jf SLUDGE J
INCINERATION
I'SLUDGE THICKENING'I i
Jl
VACUUM
FILTRATION
WASTE
SLUDGE
TO LANDFILL
f AIR
REACTOR
SECONDARY
'(3) CLARIFIERS (6)
R£CJ^CLE_SLUDGE
.CHLORINATION-
EFFLUENT
Figure 7. Flow diagram of Detroit, Michigan wastewater treatment
plant Phase #1 construction. (Printed, with modifications,
through the courtesy of the Union Carbide Corporation.)
522
-------
pletion of an expansion program at the
nearby Alexandria, Virginia plant. At that
time, the Westgate facility would cease
operations in favor of flow diversion to
Alexandria.
The first interim upgrading approach
tried was the addition of ferric chloride
to the influent wastewater at the plant
headworks followed by anionic polyelectro-
lyte addition to the aeration zones. This
technique yielded an average BOD removal
of 71 percent from July 1970 through
October 1971, somewhat short of 80 percent
removal target. The sludge resulting from
chemical addition proved to be more diffi-
cult to dewater than that of the original
plant.
Laboratory tests indicated that com-
bining powdered activated carbon dosing to
the influent wastewater with the above
iron and polyelectrolyte additions could
potentially improve BOD removal to 75 per-
cent. Full-scale trials with carbon dosing
were abandoned in July 1971 after a short-
term run due to erosion and feed control
problems. Data generated during the run
were inconclusive.
During the latter portion of 1970, the
County and its engineering consultant con-
cluded that 80 percent interim BOD removal
could be achieved more cost effectively
with a biological treatment system than
with a combination of chemical addition
procedures. A decision was then made
following technical deliberations to imple-
ment biological treatment with an oxygen-
activated sludge process rather than a
high-rate air-activated sludge process
because of reliability and cost consider-
ations. A contract was awarded to Air
Products and Chemicals, Inc. in the spring
of 1971 after competitive bidding to con-
vert the existing Westgate plant to an OASES
system. A contract period of 210 days was
allowed to complete the job.
The upgrading plan developed by the
County's engineer consisted of four prin-
cipal steps:
1. Conversion of the aeration
and secondary clarification sections of the
existing tanks into a two-train oxygenation
reactor leaving the primary clarification
sections intact.
2. Installation of two new
secondary clarifiers, each 120 ft (36.6 m)
in diameter with a SWD of 11 ft (3.4 m) and
suction lift scraper arms for removing
sludge.
3. Installation of waste acti-
vated sludge thickening capability in the
form of two flotation thickeners, each
having a surface area of 250 sq ft (23.2
sq m).
4. Installation of two 7-mgd
(0.31-cu m/sec sludge recycle pumps and
separate sludge wasting pumps.
A longitudinal section view of the
existing Westgate treatment basin prior to
conversion to an oxygen system is given in
Figure 8. Some of the modifications re-
quired to effect the conversion are noted.
These included removal of the air diffusers
and downcomer piping, removal of the baffles
between the old aeration and secondary
clarification sections, removal of all old
effluent weir sections within the secondary
clarification sections proper, removal of
the old sludge scrapers from the aeration
and secondary clarification zones, replace-
ment of the baffles separating the primary
clarification and original aeration zones,
and relocation of some sludge scraper
sprockets to the primary clarification
sections. The converted oxygen reactor
was divided into four stages in each train.
The stages comprised in order 22, 44, 23,
and 11 percent of the total reactor volume.
Only the first three stages were covered,
the last stage being left open to the at-
mosphere because of the low oxygen demand
which would exist at that point. The gas-
tight tank covers and liquid staging baffles
were fabricated from carbon steel and
coated with an epoxy-phenolic resin. The
overall dimensions of the converted oxygen
reactor are 138 ft long x 82 ft wide x 12
ft SWD (42 m x 25 m x 3.7 m).
A total of 36 surface aerators with
bottom impellers were installed for oxygen
dissolution and mixing. Eight of the
aerators (utilized at the front end of the
reactor) are 10-hp (7.5-kw) units; the
other 28 have 5-hp (3.7-kw) drives, yielding
a total installed nameplate power load of
220 hp (164 kw). Liquid oxygen is stored
on-site and vaporized preceding introduc-
tion to the oxygenation system.
Plant modifications were completed
and the converted system started up in
523
-------
PRIMARY
CLARIFICATION
OLD EFFLUENT OVERFLOW WEIR
/BAFFLE REMOVED
SPROCKETS RELOCATED
Figure 8- Longitudinal sectional view of pre-modified
concrete tank at Fairfax County (Westgate) , Virginia
wastewater treatment plant. (Reprinted from draft
report for EPA Contract No. 68-03-0405 .) (6)
November 1971, making Westgate the oldest
full-scale oxygen-activated sludge facility
in the world.
A flow diagram of the modified plant
is shown in Figure 9. Operation of the new
flotation thickeners was terminated after
several months. It was found that thicken-
ing of excess activated sludge beyond that
afforded by gravity decant tanks was not
needed prior to mixing with primary sludge
and vacuum filtration. The comminutor was
also removed from service several months
into the upgraded operation.
Start-up difficulties were minimal and
of the type normally associated with "de-
bugging" a new system. A process optimi-
zatjon program was undertaken for the County
by Air Products and Chemicals from late
January 1972 to May 1972. The primary
purpose of the program was to define the
operating conditions for this first-of-a-
kind system which would result in a con-
sistently high level of plant performance.
Operating and performance data are present-
ed in Table 10 for the one-year period of
August 1972 through July 1973. As indi-
cated, excellent effluent quality was
achieved, far exceeding the 80 percent
BOD removal design specification, at an
average influent flow equal to 76 percent
of design capacity. Primary influent
rather than reactor influent concentrations
are included in Table 10 because represen-
tative sampling of primary effluent is not
possible. Little alteration of influent
wastewater characteristics is believed to
be effected by the primaries due to their
short detention time (20-25 minutes).
The Westgate story is a superb example
of utilizing existing tankage to the fullest
in an upgrading project intended to simul-
taneously improve plant performance and
increase plant capacity. It is not known
in view of the excellent performance
achieved to date whether the upgraded
TABLE 10. OPERATING AND PERFORMANCE DATA
FOR FAIRFAX COUNTY, VIRGINIA OXYGEN SYSTEM
Operation
Aug.1972-
Parameter Design July 1973
Influent Flow (mgd)*
Aeration Detention
Time, Q (hr)
F/M Loading
(kg BOD5/day/kg MLVSS)
Secondary Clarifier Over-
flow Rate (gpd/sq ft)t
MLSS (mg/1)
Return Sludge TSS (%)
Primary Influent (mg/l)+
14
1.74
--
620
--
10.6
2.3
0.54§
469
4480
1.87
BOD5 220 161
TSS 173 162
Secondary Effluent (mg/1)
BOD5
TSS
44
12
19
*1 mgd = 0.044 cu m/sec
tl gpd/sq ft = 0.041 cu m/day/sq m
tNot possible to sample reactor influent as
only a baffle wall separates primary
clarifier from reactor.
§ Based on primary influent BOD5 rather than
reactor influent BOD5; indicated value
is, therefore, about 10 percent high.
524
-------
ABANDONED
ACTIVATED CARBON
SLURRY TANK
RECYCLE
PUMP
"F" STREET PUMPING STATION
Figure 9. Flow diagram of Fairfax County (Westgate), Virginia
wastewater treatment plant. (Reprinted from draft report
for EPA Contract No. 68-03-0405.)(6)
plant will still be abandoned when the
Alexandria expansion is completed or not.
The total cost of the Westgate upgrading
was $1,672,000, of which $861,000 was
expended for the oxygen dissolution and
supply systems and reactor tank modifi-
cations.
Gulf States Paper Corporation,
Tuscaloosa, Alabama (UNOX)
A custom-designed, self-contained, cir-
cular UNOX system was installed at the
Gulf States Paper Corporation complex in
Tuscaloosa, Alabama, to treat 9 mgd (0.39
cu m/sec) of unbleached kraft mill waste-
water. This type of wastewater is deficient
in nitrogen and phosphorus. To overcome
these deficiencies at Gulf States, phos-
phoric acid and anhydrous ammonia are
added to the primary effluent.
A custom-designed circular UNOX sys-
tem differs from one of Union Carbide's
modular package oxygen plants in that it
is not a standard off-the-shelf unit. The
Gulf States oxygen system is composed of
three above-ground steel tanks each with
a diameter of 109 ft (33.2 m), a total
depth of 20 ft-(6.1 m), and a SWD of 16 ft
(4.9 m). Each tank is divided into a four-
stage oxygenation reactor and an arcuate
clarifier. Three of the four stages are
also arcuate; one is circular. Air-lift
suction pickups are used to withdraw set-
tled sludge from the clarifiers. Oxygen
dissolution and solids mixing are accom-
plished with surface aerators and bottom
propellers. A four-bed 30-ton/day (27.2-
metric ton/day) PSA oxygen gas generator
and a 43-ton (39-metric ton) liquid oxygen
backup storage tank and atmospheric vapor-
izer comprise the oxygen supply system.
As shown in the flow diagram presented
in Figure 10, alum can be dosed to a sepa-
rate polishing clarifier following secondary
clarification for the purpose of effecting
additional color removal. This color re-
moval system has not been used to any great
extent to date, however, because of prob-
lems with the alum recovery equipment.
The oxygen system itself has been in
operation since October 1974. Following
start-up and "debugging," maintenance re-
quirements have been of a routine nature.
Operator attention on the unit ranges from
7-10 hr/week.
525
-------
Operating and performance data for the
months of April and May 1975 are summarized
in Table 11. Although the system is oper-
ating at design flow, reactor influent
strength has been averaging only about 60
percent of design expectations. It has,
PSA GENERATOR 3OTPD
therefore, not been necessary to operate
at as high MLSS levels as projected to main-
tain reasonable F/M loadings. The effluent
values shown represent product quality from
the secondary clarifiers. Additional sus-
pended solids removal is reportedly achieved
1
LOX STORAGE
T_:r_T
NUTRIENT
ADDITION
— UNOX REACTORS (3)
PRIMARY CLARIFIER
INFLUENT
O TO BLACK LIQUOR
OXIDATION
PRIMARY
SLUDGE
i
FILTRATE
ALUM ADDITION
COLOR REMOVAL
EFFLUENT
INCINERATOR I -^ |
THICKENER WASTE
SLUDGE I
FILTER PRESS
ALUM RECOVERY
ASH
Figure 10. Flow diagram of the Gulf States Paper Corporation wastewater
treatment plant - Tuscaloosa, Alabama. (Printed, with modifications,
through the courtesy of the Union Carbide Corporation.)
526
-------
in passage through the polishing clarifier
(operated without alum addition). No data
were available to the writer to document
the improvement obtained in the polishing
clarifier.
Approximately one-half of the PSA generator
output is used in the activated sludge sys-
tem; the other half is utilized for black
liquor oxidation. Because of the dual role
served by the oxygen supply facilities, the
PSA unit was designed to produce 95 percent
purity oxygen gas rather than the standard
90 percent product purity normally associ-
ated with PSA operation.
TABLE 11. OPERATING AND PERFORMANCE DATA
FOR GULF STATES PAPER OXYGEN SYSTEM
Operation
Apr. May
Parameter Design 1975
Influent Flow (mgd)*
Aeration Detention
Time, Q (hr)
F/M Loading
(kg BOD5/day/kg MLVSS)
Secondary Clarifier Over-
flow Rate (gpd/sq ft)f
MLSS (mg/1)
Return Sludge TSS (%)
Reactor Influent (mg/1)
BOD5
TSS
Secondary Effluent (mg/1)
BOD5
TSS
9.0
3.33
0.36
630
4700
1.9
200
100
30
50
9.0
3.33
0.37
630
3000
1.2
125
60
12
50
*1 mgd = 0.044 cu m/sec
tl gpd/sq ft = 0.041 cu m/day/sq m
Lederle Laboratories, Pearl River,
New York (UNOX)
Lederle Laboratories, a division of
American Cyanamid, manufactures pharma-
ceuticals, the majority of which are anti-
biotics. The waste stream resulting from
production operations has a very high and
variable organic carbon content. The plant
wastewater flow which remains relatively
constant at about 1.0 mgd (0.044 cu m/sec)
can have a BOD5 loading as high as 32,500
Ib/day (14,740 kg/day).
Prior to the spring of 1972, an air
aeration system was used to treat plant
wastes. The daily operations of this sys-
tem were marked by persistent odor problems
and inconsistent performance, arising from
the highly variable organic load. A UNOX
system was designed to replace the existing
air aeration facilities. Start-up occurred
in March 1972, which makes it the oldest
permanent full-scale UNOX facility in
existence.
A flow diagram of the new oxygenation
treatment plant is given in Figure 11. The
two-train reactor has overall dimensions of
148 ft long x 74 ft wide x 14.5 ft deep
(45 m x 22.6 m x 4.4 m) with a SWD of 10 ft
(3.0 m). The lead reactor stages are larger
than the second or third stages to accom-
modate the high oxygen demand of the in-
coming wastewater. Polymers are added
ahead of the single primary clarifloccula-
tor to lower the suspended solids concen-
tration entering the secondary system as
much as possible. The three circular sec-
ondary clarifiers each have a 40-ft (12.2-
m) diameter, a 10-ft (3.0-m) SWD, and a
plow-type sludge scraper. A 15-ton/day
(13.6-metric ton/day) PSA generator and a
52-ton (47-metric ton) liquid oxygen back-
up tank provide oxygen supply.
Start-up difficulties included a
foaming tendency which ceased once a good
biomass had been established, and mixed
liquor solids deposition caused by recycle
of large amounts of lime and alum precipi-
tates in the filtrate from the vacuum
filter which are not effectively captured
in the primary clariflocculator. Solids
deposition was alleviated by adding bottom
mixers to the initially supplied surface
aerators. The PSA oxygen generator experi-
enced upwards of 10 percent outage follow-
ing start-up due to valve actuator problems.
This unit was one of the first on-line
molecular sieve applications geared to
producing oxygen gas for wastewater treat-
ment. As such, some experimentation was
necessary to determine proper lubricating
procedures for the valve actuators and to
procure sufficiently rugged valve equipment
to withstand rapid cycling. Following
final modifications in mid-1973, total un-
scheduled PSA generator downtime has been
reduced to less than one percent.
Odor complaints from neighboring
residents numbered more than 80 in 1971.
Complaints have not been received since
the oxygen system went into operation.
527
-------
PSA GENERATOR 15 TPD
GRIT
CHAMBER
PRIMARY
CLARIFLOCCULATOR
INFLUENT
J
LOX
STORAGE
UNOX REACTOR
PRIMARY
SLUDGE
RECYCLE SLUDGE
SECONDARY CLARIFIERS
—-CHLORINATION
EFFLUENT1 '
^ FILTRATE
EFFLUENT
POLISHING
I -^- WASTE SLUDGE I J
TO LANDFILL
_^ • I i ^_
^-k. VACUUM If |r^
-------
TABLE 12. OPERATING AND PERFORMANCE DATA
FOR LEDERLE LABORATORIES OXYGEN SYSTEM
Operation
Parameter
Influent Flow (mgd)*
Aeration Detention Time, Q (hr)
F/M Loading
(kg BODs/day/kg MLVSS)
Secondary Clarifier Overflow
Rate (gpd/sq £t)t
MLSS (mg/1)
Return Sludge TSS (%)
Reactor Influent BOD5 (mg/1)
TSS (mg/1)
Polishing Clarifier Effluent BOD5 (mg/1)
TSS (mg/1)
Design
1.5
13
0.42
540
8000
2.8
1600
--
160
--
2 Trains
Oct. 1972
1.0
19.5
0.17
360
11,500
3.5
1400
800
80
70
1 Train
Nov. 1972
(3 weeks)
1.0
9.75
0.45
360
9600
3.0
1500
1300
90
60
*1 mgd = 0.044 cu m/sec
tl gpd/sq ft = 0.041 cu m/day/sq m
clarifiers have been corrected. Settled
sludge no longer fills up the secondaries
and spills over into the polishing clari-
fier. With the polishing clarifier serving
in its intended role, effluent 6005 and
suspended solids concentrations now gener-
ally average around 50 and 10 mg/1, respec-
tively.
Littleton, Colorado (UNOX)
The City of Littleton, Colorado, se-
lected a modular UNOX system for a recent
plant expansion. The modular unit used for
Littleton is an off-the-shelf package sys-
tem contained within one circular above-
ground steel tank. The tank, 82 ft (25 m)
in diameter x 15 ft (4.6 m) deep [SWD = 12
ft (3.7 m)], is divided by internal walls
into a two-stage oxygen reactor, an arcuate
secondary clarifier; a single-stage air
aerobic sludge digester, and a chlorine
contact chamber. The arcuate clarifier is
equipped with floating bridge mounted air
lift suction equipment for withdrawing
settled sludge.
The new oxygen train operates in par-
allel with two existing trickling filters.
Feed to the trickling filters is first set-
tled in the plant's existing primary clari-
fier. The oxygen reactor receives raw
degritted municipal wastewater directly.
A flow diagram for the Littleton plant is
presented in Figure 12.
The combined liquid volume of the two
oxygen reactor stages is 97,000 gal (367
cu m). Surface aerators connected by
shafts to bottom propellers are employed
for oxygen dissolution and mixing. Due to
the small size of the treatment plant, an
on-site oxygen gas generating facility was
not provided. Instead, liquid oxygen is
trucked in and stored in a 43-ton (39-
metric ton) tank, from where it is dir-
ected through an atmospheric vaporizer for
conversion to the gaseous form before
entering the oxygenation reactor.
The UNOX package system became oper-
ational in February 1974. A major oper-
ating difficulty was immediately encountered.
The original uncovered air aerobic sludge
digester was equipped with mechanical sur-
face aerators. Aerator icing occurred in
the cold Colorado winter climate with re-
sulting poor volatile suspended solids
(VSS) reduction. The problem was rectified
by installing a steel cover over the di-
gester area along with urethane foam insu-
lation and supplementing the surface aer-
ators with an air blower and diffusers to
provide adequate air circulation. VSS re-
ductions have since ranged from 50-60 per-
cent .
Influent flow to the oxygen portion of
the Littleton plant has varied from 0.9 mgd
529
-------
GRIT CHAMBER
TRICKLING FILTERS(2)
INFLUENT
SUPERN
FINAL CLARIFIER
k
ATAIMT
_^__ WASTE SLUDGE
I -*——
PRIMARY ANEROBIC DIGESTER — ——-'
SUPERNATANT
I
I
*
SECONDARY DIGESTER
I »
I
J
CHLORINATION
UNOX REACTOR
SLUDGE DRYING BEDS
.— TO LANDFILL
EFFLUENT
Figure 12. Flow diagram of Littleton, Colorado wastewater
treatment plant. (Printed, with modifications, through
the courtesy of the Union Carbide Corporation.)
(0.04 cu m/sec) to 1.4 mgd (0.06 cu m/sec)
since start-up. The three-month average
data summarized in Table 13 for the summer
1975 period indicate the oxygen system is
performing within effluent design specifi-
cations.
Morganton, North Carolina (UNOX)
A UNOX facility designed to treat 8 mgd
(0.35 cu m/sec) of municipal wastewater
combined with substantial industrial con-
tributions resulting from textiles produc-
tion and poultry processing went on-stream
at Morganton, North Carolina, in January
1975. As indicated in the plant flow dia-
gram (Figure 13), primary clarification was
not included in the design. The two-train
oxygen reactor was constructed in an un-
usual box configuration with four stages
per train. Each stage is 44 ft (13.4 m)
square yielding overall length and width
dimensions of 88 ft (26.8 m) and 176 ft
(53.6 m), respectively. The total reactor
depth is 14 ft (4.3 m) including a 4-ft.
(1.2-m) freeboard.
Oxygen system equipment consists of
surface aerators with bottom impellers for
oxygen dissolution and mixing and a 26-ton/
530
-------
TABLE 13. OPERATING AND PERFORMANCE DATA
FOR LITTLETON, COLORADO OXYGEN SYSTEM
Parameter
Operation
June-Aug.
Design 1975
Influent Flow (mgd)*
Aeration Detention
Time, Q (hr)
F/M Loading
(kg BOD5/day/kg MLVSS)
Secondary Clarifier Over-
flow Rate (gpd/sq ft)t
MLSS (mg/1)
Return Sludge TSS (%)
Reactor Influent (mg/1)
BOD5
TSS
Secondary Effluent (mg/1)
BOD5
TSS
1.25
1.9
0.6
500
5600
2.8
200
240
20
25
1.1
2.16
0.6
440
4000
2.4
160
185
12
24
*1 mgd = 0.044 cu m/sec
tl gpd/sq ft = 0.041 cu m/day/sq m
day (23.6-metric ton/day) PSA generator
and 28-ton (25.4-metric ton) liquid oxygen
backup tank for oxygen supply. The PSA
generator was outfitted initially with one
one-half size compressor. A second half-
size compressor will be added at a later
date when plant flows increase. The two
new secondary clarifiers are 80-ft (24.4-m)
diameter units with 10-ft (3.0-m) SWD's and
rapid sludge removal and grease skimming
capabilities.
Process and mechanical reliability have
been excellent in the year and half since
start-up. PSA generator availability has
exceeded 99.5 percent. A major operational
problem in the form of high fat and grease
loadings (often in excess of 100 mg/1) from
the local poultry processor, however, has
prevented consistent attainment of effluent
quality objectives. No satisfactory method
exists for rejecting these objectionable
materials from the secondary system. The
fat and grease which are only slowly bio-
degradable pass to the final clarifiers
and collect on the liquid surfaces. Al-
though skimming devices were provided, much
of the scum escapes the finals over the
weirs taking with it significant quantities
of enmeshed biofloc. Consequently, effluent
suspended solids have reached levels as
high as 80-100 mg/1. The problem is further
accentuated by a hydraulic regime which
transports final clarifier skimmings to the
aerobic digesters and then recycles the
digester skimmings to the plant headworks
for recycle through the secondary system.
Efforts to remove a large fraction of
the fat and grease load through pretreat-
ment at the poultry processing site have
been unsuccessful. Consideration is now
being given to intercepting the skimmings
from the aerobic digesters and disposing of
them separately. When this technique has
been evaluated for short periods on a trial
basis, effluent clarity and suspended solids
removals have improved measurably. The
difficulties encountered at Morganton
appear to the writer to consitute a com-
pelling argument for the inclusion of pri-
mary clarification facilities in any future
designs faced with similar wastewater char-
acteristics.
Two months of operating and perform-
ance data are summarized in Table 14. Ef-
fluent quality documented for March 1975 is
typical of months when the influent grease
load has been somewhat lower than normal
and represents about the best performance
level that can be achieved under present
conditions. In April 1975, the influent
grease load was up, and the monthly average
effluent suspended solids concentration in-
creased accordingly. The much higher than
anticipated influent suspended solids con-
centrations for these two months indicate
that primary clarification would probably
have been a desirable and justifiable
feature aside from grease removal consider-
ations.
North Lauderdale, Florida (UNOX)
An off-the-shelf modular UNOX system
was installed at North Lauderdale, Florida,
to serve a population base of approximately
10,000 people. This package system consists
of a two-stage oxygen reactor, an arcuate
secondary clarifier, and an uncovered single-
stage air aerobic sludge digester. The ar-
cuate clarifier has an air lift suction
device mounted from a floating bridge for
removing settled sludge. The air aerobic
digester is equipped only with mechanical
surface aerators: it was not necessary to
provide supplemental compressed air as at
Littleton.
The entire secondary complex is con-
tained within one circular. 95-ft (29-m) dia-
531
-------
PSA GENERATOR 26 TPD
LOX STORAGE
BAR SCREEN
UNOX REACTOR
f
ii
INFLUENT
RECYCLE SLUDGE
T
1 AERATED GRIT 1
I
EFFLUENT
SECONDARY
CLARIFIERS (2)
11
CHLORINATION
V
I df CENTRIFUGES (2)'
POLYMER , | X-V I
—i ^— — — i —• \—t ^^ ^J •
CENTRATE
TO LANDFILL
Figure 13. Flow diagram of Morganton, North Carolina wastewater
treatment plant. (Printed, with modifications, through the
courtesy of the Union Carbide Corporation.)
meter, 15-ft (4.6-m) deep, above-ground steel
tank. The tank's SWD is 12 ft (3.7 m). Un-
like the Littleton modular unit, a separate
external chlorine contact chamber was pro-
vided rather than including it in the pack-
age system. Granular media filters are
available for effluent polishing, although
to date they have not been used. Raw
degritted municipal wastewater is fed di-
rectly to the oxygen system. Excess acti-
vated sludge is dewatered either by cen-
trifugation or on sand drying beds. A flow
diagram of the new North Lauderdale treat-
ment plant is shown in Figure 14.
Oxygen dissolution and mixing are ac-
complished in the 129,000-gal (488-cu m)
oxygen reactor with surface aerators and
supplemental bottom agitators. A 43-ton
(39-metric ton) liquid oxygen storage tank
and attendant atmospheric vaporizer com-
prise the oxygen supply system.
The plant was placed in operation in
early July 1975. To date, influent flow has
been averaging only about 65 percent of the
design flow of 2 mgd (0.09 cu m/sec), al-
though wastewater strength has been some-
what higher than anticipated. No signifi-
cant operating problems have been encount-
ered. Performance as exhibited by the
average data for September 1975 shown in
Table 15 has been excellent.
532
-------
TABLE 14. OPERATING AND PERFORMANCE DATA
FOR MORGANTON, NORTH CAROLINA OXYGEN SYSTEM
Operation
Parameter
Design March APril
K 1975 1975
Influent Flow (mgd)*
Aeration Detention Time, Q (hr)
F/M Loading
(kg BOD5/day/kg MLVSS
Secondary Clarifier Overflow
Rate (gpd/sq ft)f
MLSS (mg/1)
Return Sludge TSS (%)
Reactor Influent BOD (mg/1)
TSSb(mg/l)
Secondary Effluent BOD (mg/1)
TSSb(mg/l)
8.0
3.5
0.53
800
6000
3.0
350
400
27
25
4.7
6.0
0.31
470
5600
2.1
364
836
42
29
5.9
4.7
0.33
590
6400
1.6
357
946
32
79
*1 mgd = 0.044 cu m/sec
tl gpd/sq ft = 0.041 cu m/day/sq m
TABLE 15. OPERATING AND PERFORMANCE DATA
FOR NORTH LAUDERDALE, FLORIDA OXYGEN SYSTEM
Operation
Parameter
Influent Flow (mgd)*
Aeration Detention
Time, Q (hr)
F/M Loading
(kg BODs/day/kg MLVSS)
Seconday Clarifier Over-
flow Rate (gpd/sq ft)t
MLSS (mg/1)
Return Sludge TSS (%)
Reactor Influent (mg/1)
BOD5
TSS
Secondary Effluent (mg/1)
BOD 5
TSS
Design
2.0
1.56
0.68
525
5600
2
200
130
20
20
Sept. 1975
1.3
2.4
0.68
541
4500
1.5*
245
180
<10
<10
1 mgd = 0.044 cu m/sec
tl gpd/sq ft = 0.041 cu m/day/sq m
return sludge rate
Speedway, Indiana (UNOX)
In June 1972, a new 7.5 mgd (0.33 cu m/
sec) UNOX installation was placed in oper-
ation at Speedway, Indiana. This was the
first municipal UNOX facility to be com-
pleted. Of all the oxygen-activated sludge
wastewater treatment systems now in oper-
ation, the Speedway plant was preceded only
by the municipal OASES plant at Fairfax
County, Virginia, and the industrial UNOX
plant at the Lederle Laboratories in Pearl
River, New York.
The flow diagram in Figure 15 indicates
that the Speedway oxygen system is of con-
ventional design. The two-train oxygen re-
actor is preceded by primary clarification.
Three of the six primaries are existing
units; the other three are converted sec-
ondary clarifiers from the City's old
trickling filter treatment facility. Each
of the four reactor stages per train is
22 ft (6.7 m) square with a 16-ft (4.9-m)
SWD. The overall dimensions of the two
reactor tanks taken together are 88 ft long
x 44 ft wide x 20 ft deep (26.8 m x 13.4 m
x 6.1 m). Three new 65-ft (19.8-m) dia-
meter, 10-ft (3.0-m) SWD secondary clari-
fiers with the increasingly popular rapid
method of removing settled sludge were
provided. At a future date as needed,
plant capacity can be increased to 10 mgd
(0.44 cu m/sec) by the construction of one
additional secondary clarifier.
The UNOX reactors were designed to use
surface aerators attached by shafts to
bottom agitators for oxygen dissolution
and mixing. A three-bed 5-ton/day (4.4-
metric ton/day) PSA unit generates oxygen
gas on-site. A 7-ton (6.4-metric ton)
liquid oxygen storage tank and accompanying
atmospheric vaporizer were furnished for
reserve. Profiting from difficulties ex-
perienced with earlier four-bed PSA gen-
533
-------
BAR SCREEN
INFLUENT
COMMINUTOR
UNOX REACTOR
TO LANDFILL
SUPERNATANT
SLUDGE
CHLORINE INJECTION
CENTRIFUGES V- —r ——'
I DRYING BEDS
CHLORINE CONTACT CHAMBER
Figure 14. Flow diagram of North Lauderdale, Florida wastewater
treatment plant. (Printed, with modifications, through the
courtesy of the Union Carbide Corporation.)
erator designs at Lederle Laboratories and
on a U.S. EPA co-sponsored demonstration
grant project at the Newtown Creek plant in
Brooklyn, New York (3), particularly as
related to valves and lubricants, the sec-
ond generation three-bed design employed
at Speedway has proven to be highly reli-
able with less than 1-1/2 percent total
downtime for scheduled and unscheduled
maintenance.
Waste activated sludge is recycled to
the primaries for co-thickening with raw
sludge. The mixed sludges are then pumped
to a holding tank which feeds a Zimpro wet
oxidation system designed to condition
sludge for dewatering. Conditioned sludge
is dewatered by vacuum filtration prior
to being trucked to landfill. Periodic
and lengthy shutdowns of the wet oxidation
system placed considerable stress on the
main stream treatment components for much
of the early history of this new facility.
Unable to truck liquid sludges away, it
was frequently necessary to return mixed
raw and waste sludges from the sludge
holding tank to the primary clarifiers.
When the primaries filled up, sludge over-
flowed into the oxygen reactors along with
primary effluent. The oxygenation tanks
during these periods in effect served
more as aerobic sludge digesters than
conventional activated sludge systems.
Considering the difficulties imposed
by the above conditions on the management of
534
-------
PSA GENERATOR 5 TPD
LOX STORAGE
GRIT PRIMARY CLARIFIERS (6) '
REMOVAL
UNOX REACTOR
SCREEN
ji
1
| WASTE SLUDGE
MIXED
SLUDGE
A
SECONDARY CLARIFIERS
CHLORINATION
-*-V
EFFLUENT
L.
HOLDING TANKS (2) ZIMPRO
RECYCLE SLUDGE
SUPERNATANT
L_ . . . v — — . .
— _ ~"t^_ FILTRA_[E J._— ILK
Figure 15. Flow diagram of Speedway, Indiana wastewater
treatment plant. (Printed, with modifications, through
the courtesy of the Union Carbide Corporation.)
VACUUM
FILTER
secondary sludge inventory, oxygen system
performance was superb. Annual average
effluent 6005 and suspended solids con-
centrations were low in both 1973 and 1974,
as indicated in Table 16. The highest
monthly average BODs and suspended solids
levels recorded in these two years were
16 and 30 mg/1, respectively. Also shown
in Table 16 are the results of one month
of one-train operation in early 1976.
Occasional one-train operating tests have
been conducted by plant personnel to
evaluate oxygen system performance at
loadings comparable to design values.
Union Carbide Corporation,
Sistersville, West Virginia (UNOX)
The Chemicals and Plastics Division
of the Union Carbide Corporation placed a
UNOX system in operation in November 1973
to treat waste products from the manufacture
of silicones. The resulting wastewater
stream has a high organic carbon content and
also contains substantial quantities of
acid and various oils. Conditioning is
necessary ahead of the biological process
to neutralize the acid and remove the oil.
A holding pond (not included in the flow
535
-------
TABLE 16. OPERATING AND PERFORMANCE DATA
FOR SPEEDWAY, INDIANA OXYGEN SYSTEM
2 Trains*
1973 1974
Operation
Parameter
Design
1 Traint
Jan. 16 -
Feb. 18, 1976
Influent Flow (mgd)*
Aeration Detention Time, Q (hr)
F/M Loading
(kg BOD5/day/kg MLVSS)
Secondary Clarifier Overflow
Rate (gpd/sq ft)§
MLSS (mg/1)
Return Sludge TSS (mg/1)
Reactor Influent BODs (mg/1)
TSS (mg/1)
Secondary Effluent BOD5 (mg/1)
TSS (mg/1)
7.5
1.48
0.51
750
4200
2.2
110
96
15
20
4.4
2.52
0.20
440
6080
1.54
91
179
9
16
4.6
2.41
0.51
460
6600
1.3
73
109
9
14
4.3
1.29
0.70
645
4760
1.66«
114
118
13
18
*Three secondary clarifiers in operation
tTwo secondary clarifiers in operation
*1 mgd = 0.044 cu m/sec
§1 gpd/sq ft = 0.041 cu m/day/sq m
^Excludes reported values for Feb. 6, 1 -, 8, and 9
diagram shown in Figure 16) is utilized
for diversion of large spills that cannot
be adequately preconditioned.
This inhouse Carbide project marked the
first utilization of circular reactor/clari-
fier UNOX combination tanks. Two such
units were installed, each consisting of
three arcuate reactor stages and one cir-
cular reactor stage and an arcuate final
clarifier. In contrast to the above-ground
designs employed in later circular UNOX
facilities (refer to Gulf Stages Paper Cor-
poration; Littleton, Colorado; and North
Lauderdale, Florida), the Sistersville
tanks were installed in conventional below-
ground fashion. The custom-designed dimen-
sions of the Sistersville units are:
diameter 102 ft (31.1 m), total depth -
14 ft (4.3 m), and SWD - 10 ft (3.1 m).
The final clarifiers are equipped with air-
lift suction equipment for removing settled
sludge.
Surface aerators connected to bottom
impellers are used to achieve oxygen dis-
solution and oxygen and biomass dispersion.
Oxygen is supplied in a rather unusual
manner from an on-site industrial cryogenic
nitrogen gas generator which produces 15
tons/day (13.6 metric tons/day) of oxygen
gas as a by-product. Prior to start-up of
the silicones wastewater treatment facility,
the by-product oxygen was wasted to the
atmosphere.
Problems were initially encountered
with the floating bridge mechanism from
which the sludge scraping and pickup devices
are supported. Corrective action required
redesign and relocation of the bridge cen-
ter support. Later arcuate clarifier de-
signs profited from the Sistersville experi-
ences .
Occasional toxic spills, primarily
from copper, have resulted in biological
upsets. The oxygen-activated sludge sys-
tem has usually recovered from these spills
within one week. Following an in-plant
survey, a program is underway to eliminate
copper from plant discharges in concentra-
tions which are toxic to microorganisms.
Average monthly operating and perform-
ance data for August and December 1975 are
presented in Table 17. At influent load-
ings equal to 85-95 percent of hydraulic
capacity, effluent quality has been signifi-
cantly better than required by the design
specifications. The difficulty in settling
silicone fines can be noted in the effluent
suspended solids levels which are two to
three times the effluent BOD,- concentrations.
536
-------
CRYOGENIC GENERATOR 15 TPD
LOX STORAGE
UNOX REACTORS (2)
NUTRIENT
LIME ADDITION ADDITION
t PRIMARY API EQUIL.ZATION
SEPARATOR BASIN
11
EFFLUENT
DEWATERING POND |
INFLUENT
SUPERNATANT
TO LANDFILL
Figure 16. Flow diagram of Union Carbide Corporation wastewater
treatment plant - Sistersville, West Virginia. (Printed,
with modifications, through the courtesy of the Union Carbide Corpoation.J
Winnipeg, Manitoba (UNOX)
One of the more attractive oxygen-
activated sludge plants now in operation
is located at Winnipeg, Manitoba, Canada.
This 12-mgd (0.53-cu m/sec) treatment facil-
ity was designed to operate over a wide air
temperature range (100°F in summer to -50°F
in winter) and is, therefore, totally
housed with the exception of the covered
UNOX reactor.
The plant utilizes a conventional flow
scheme to treat municipal wastewater. Pri-
mary clarification is utilized ahead of a
two-train, three-stage/train, oxygenation
reactor having overall dimensions of 120 ft
long x 60 ft wide x 19.5 ft deep (36.6 m x
18.3 m x 5.9 m ). The reactor's SWD is 16
ft (4.9 m). Mixed liquor flow is evenly
divided between two 110-ft (33.5-m) diam-
eter final clarifiers. The SWD of the finals
is 10 ft (3.0 m). As with most recently-
537
-------
TABLE 17. OPERATING AND PERFORMANCE DATA FOR
UNION CARBIDE SISTERSVILLE OXYGEN SYSTEM
Operation
Parameter
Design
Aug. 1975
Dec. 1975
Influent Flow (mgd)* 4.3
Aeration Detention Time, Q (hr) 3.5
F/M Loading
(kg BOD5/day/kg MLVSS) 0.85
Secondary Clarifier Overflow
Rate (gpd/sq ft)t 600
MLSS (mg/1) 5000
Return Sludge TSS (%) 2.0
Reactor Influent (mg/1)
BOD5 370
TSS <100
Secondary Effluent (mg/1)
* 1 mgd = 0.44 cu m/sec
t 1 gpd/sq ft = 0.041 cu m/day/sq m
$ High sludge return rate
3.6
4.2
0.75
502
4500
1.0*
425
75
4.1
3.7
0.90
572
3900
2.0
339
103
BOD5
TSS
50
<100
25
70
20
43
constructed circular clarifiers, rapid
sludge removal equipment was provided
rather than the older plow-type scrapers.
Primary and waste activated sludges are
mixed and centrifuged before undergoing
incineration. The flow diagram for the
plant is given in Figure 17.
The UNOX system components selected
for Winnipeg include surface aerators and
bottom mixers for oxygen dissolution and a
10-ton/day (9.1-metric ton/day) PSA oxygen
gas generator and 14-ton (12.7-metric ton)
liquid oxygen backup tank for oxygen supply.
Considerable difficulty has been experi-
enced with the operation of the PSA com-
pressor. This machine was initially out-
fitted with internal clearance pocket un-
loaders. These unloaders did not function
properly resulting in the imposition of un-
due stress on and excessive wear of com-
pressor bearings and bushings. Frequent
outages were necessary to overhaul the
worn parts. Eventually in late 1975, the
compressor was completely rebuilt and the
clearance pocket unloaders replaced with
suction pocket unloaders. Except for one
subsequent unscheduled outage due to a
heater failure, the compressor has worked
well since then.
System start-up occurred in September
1974. No process related difficulties have
been encountered. Operation at cold mixed
liquor temperatures down to 10°C has not
induced growth of filamentous organisms or
any other noticeable sludge settling prob-
lems. In early 1975, official one-month
performance tests were conducted with only
one reactor train in service and with both
reactor trains in service. Both final
clarifiers were used during each test. The
results of the tests are documented in
Table 18. In each case, although the aer-
ation detention time was less than and the
F/M loading higher than design, effluent
BOD5 and suspended solids concentrations
were significantly lower than required by
design stipulations..
ACKNOWLEDGEMENTS
Information on oxygen systems in
various stages of implementation was
supplied by the Union Carbide Corporation;
Air Products and Chemicals, Inc.; and the
FMC Corporation. Case history data and
flow diagrams for UNOX plants in operation
were provided by the Union Carbide Corpor-
ation. Case history data and pertinent
diagrams for the OASES plant at Fairfax
County; Virginia, were extracted from the
final report draft (5) (publication pending)
for U. S. EPA Contract No. 68-03-0405.
538
-------
PSA GENERATOR 12 TPD
PRE-CHLORINATION
AGRRITED PRIMARY
CHAMBER CLARIFIERS
LOX STORAGE
UNOX REACTOR
INFLUENT
BAR
| GRIT PRIMARY!
SCREENS I I • ---
SLUDGE
FINAL CLARIFIERS (2)
i SLUDGE HOLDING TANK JWASTE
* JSLUDGE
RECYCLE SLUDGE
j -^- CENTRA!
MIXED
SLUDGE
BASKET CENTRIFUGE
CHLORINATION
]
EFFLUENT
TO MAIN PLANT INCINERATOR
Figure 17. Flow diagram of Winnipeg, Manitoba wastewater treatment
plant. (Printed, with modifications, through the courtesy of
the Union Carbide Corporation.)
Process design and equipment criteria for
and visual representations of the MAROX
process were taken from FMC Corporation
advertising literature (4), supplemented
by information derived from personal
communications with FMC. Progress reports
and other information on file at the U. S.
EPA's Municipal Environmental Research
Laboratory for Grant No. S803910 formed
the basis of the discussion of Metropolitan
Denver's MAROX demonstration project.
Flow and dimensioned diagrams of the Denver
MAROX test bay were reprinted from an FMC
project bulletin (6).
The assistance of staff members of the
above three firms who contributed in
supplying the above described information
is gratefully acknowledged, including
Ruth Fauth, Robert Kulperger, David Sorensen,
Michael Lutz, Randy Dievendorf, and Ronald
Grader of Union Carbide; O.Roy Langslet
of Air Products and Chemicals; and Duane
Parker and W. Phillip Key of FMC. Special
thanks is extended to Ms. Fauth who spent
many days collecting and verifying oxygen
plant status data. The cooperation of
Richard Kaptain, Assistant Plant Manager
for the City of Decatur, Illinois, in
providing additional details for the Decatur
UNOX case history is also appreciated.
539
-------
TABLE 18. OPERATING AND PERFORMANCE DATA
FOR WINNIPEG, MANITOBA OXYGEN SYSTEM
Operation
Parameter
1 Reactor Train * 2 Reactor Trains
Design Jan. 1975 Apr. 1975
Influent Flow (mgd)*
Aeration Detention Time, Q (hr)
F/M Loading
(kg BOD5/day/kg MLVSS)
Secondary Clarifier Overflow
Rate (gpd/sq ft)t
MLSS (mg/1)
Return Sludge TSS (%)
Reactor Influent (mg/1)
BOD5
TSS
Secondary Effluent (mg/1)
BOD5
TSS
12
1.74
0.46
630
5000
2.2
133
100
25
30
8.5
1.23
0.99
446
5950
1.9
244
290
20
17
13.4
1.59
0.62
704
5100
1.6
150
193
17
13
* 1 mgd = 0.044 cu m/sec
t 1 gpd/sq ft = 0.041 cu m/day/sq m
$ Both final clarifiers in service
2.
3.
REFERENCES
Albertsson, J. G., McWhirter, J. R.,
Robinson, E. K., and Vahldieck, N. P.,
"Investigation of the Use of High
Purity Oxygen Aeration in the
Conventional Activated Sludge Process,
Water Pollution Control Research
Series Report No. 17050 DNW 05/70,
Federal Water Quality Administration,
Cincinnati, Ohio, May 1970.
Brenner, R. C., "Summary Description
of Oxygen Aeration Systems in the
United States," Proceedings of the
Second U. S.-Japan Conference on
Sewage Treatment Technology,
Cincinnati, Ohio, December 1972.
Brenner, R. C., "EPA Experiences in
Oxygen-Activated Sludge," Prepared
for Office of Technology Transfer
Design Seminar Program, U. S.
Environmental Protection Agency,
Cincinnati, Ohio, October 1974.
4. FMC Corporation, "FMC Pure Oxygen
Wastewater Treatment in Open Tanks,"
FMC Bulletin 8000-A, Itasca, Illinois,
1976.
5. FMC Corporation, "FMC Pure Oxygen
System at Metropolitan Denver Sewage
Disposal District No. 1," FMC Project
Report 8000.1, Itasca, Illinois, 1976.
6. McDowell, C. S., and Giannelli, J.,
"Oxygen-Activated Sludge Plant
Completes Two Years of Successful
Operation," Draft Report for
Contract No. 68-03-0405 with Air
Products and Chemicals, Inc., U. S.
Environmental Protection Agency,
Cincinnati, Ohio, Publication Pending.
540
-------
APPENDIX A. OXYGEN-ACTIVATED SLUDGE PLANTS IN
OPERATION AS OF JUNE 1976
1.
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.
1.
Location
USA
Alton Box Board -
Jacksonville, Fla.
Baychem Corp. , Chemagro
Div. - Kansas City, Kan.
Brunswick, Ga.
Chaska, Minn.
Chesapeake Corp. West Point, Va.
Container Corp. -
Fernandino Beach, Fla.
Decatur, 111.
Deer Park, Tex.
Denver (#2), Colo.
Detroit (#1) , Mich.
Fairfax County, Va.
Fayetteville, N.C.
Fibreboard Corp. - Antioch, Calif
Ft. Myers, Fla.
French Paper Co. Niles, Mich.
Gulf States Paper Corp.
Tusaloosa, Ala
Hamburg (#1), N. Y.
Hercules, Inc. Wilmington, N.C.
Hollywood, Fla.
Jacksonville (#1), Fla.
Lederle Laboratories Div. of
American Cyanamid-Pearl River, N.Y.
Littleton, Colo.
Morganton , N.C.
Morrisville, Pa.
Newtown Creek New York City, N.Y.
North Lauderdale, Fla.
Quail Valley, Tex.
Speedway, Ind.
Standard Brands - Peeksville, N.Y.
Union Carbide Corp. - Marietta, Ga.
Union Carbide Corp. - Sistersville,
W. Va.
Union Carbide Corp. Taft, La.
Weyerhauser Corp. Everett, Wash.
Wyandotte, Mich.
Yuba City, Calif.
TOTAL
Canada
Winnipeg, Manitoba
Installed
Design 02 Supply
Flow Capacity
(mgd)* (tons/day)f
6
4.32
10
1.25
16.25
25
17
5
10
300
14
14
16
5
0.8
10
1
1
36
5
1.5
1.5
8
4.6
20
2
1.5
7.5
1
1.26
4.33
3.8
3
100
7
664.61
12
25
50
16
1.25
34
50
17
6
7.5
180
10
18
35
9
1
30
0.5
15
50
20
15
0.5
26
4
14
1
2
4
5
1
15
88
25
60
21
856.45
10
Appli-
cation*
I-PP
I-C
M
M
I-PP
I-PP(b)
M
M
M
M
M
M
I-PP(b)
M
I-PP
I-PP
M
I-C
M
M
I-PH
M(d)
M
M
M
M(d)
M
M
I-FP
I-C
I-C
I-PC
I-PP
M
M
M
02 Dis-
solution
System§
UNOX (A)
UNOX (A)
UNOX (A)
OASES (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
MAROX (R)
UNOX (T)
OASES (A)
OASES (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
OASES (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (T)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (T)
UNOX (A)
UNOX (T)
UNOX (A)
UNOX (A)
Supply
System01
CRYO
CRYO
PSA
LIQ
CRYO
CRYO
PSA
PSA
LIQ
CRYO
LIQ
CRYO
PIPE
PSA
LIQ
PSA
LIQ
PIPE
CRYO
PSA
PSA
LIQ
PSA
PSA
PSA
LIQ
PSA
PSA
LIQ
LIQ
PIPE
PIPE
PIPE
PSA
PSA
PSA
541
-------
APPENDIX A, Continued
Location
Design
Flow
(mgd)*
Installed
02 Supply
Capacity
(tons/day)t
Appli-
cation
02 Dis-
solution
System§
Supply
System"
1. Electro Chemical Industrial Co. - 2.64 n.d.** I-PC
Ichihara City
2. Gotsu Plant Katano City 0.73 n.d. M
3. Ikuta Plant -Kawasaki City 0.61 n.d. M
4. Ju jo Paper Kushiro City 1.59 n.d. I-PP
5. Kasuga Plant Oita City 0.26 n.d. M
6. Mitsubishi Chemical Industries 1.9 n.d. I-PC
7. Nissho Kayaku Petrochemical 0.74 n.d. I-PC
Complex - Oita City
8. Oji Paper Kasugai City 18.5 n.d. I-PP
9. Oji Paper Tomakomai City 13.2 n.d. I-PP
10. Sanyo Kakusaku Pulp - Iwakuni City 0.89 n.d. I-PP
11. Showa Neoprene Kawasaki City 0.79 n.d. I-SR
12. Sumitomo Chemical Ichihara City 0.79 n.d. I-PC
13. Uenodai Plant, Japan Housing Corp. 0.52 n.d. M
Kamifukuoka City
14. Yakult Pharmaceutical Industries - 0.19 n.d. I-PH
Osaka City _
TOTAL 43.35
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
n.d.<
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
MAROX (R) n.d.
*1 mgd = 0.044 cu m/sec
i'l ton/day = 0.907 metric ton/day
+ I-C = Industrial-Chemicals
I-FP = Industrial-Food Processing
I-PC = Industrical-Petrochemical
I-PH = Industrial-Pharmaceutical
I-PP = Industrial-Pulp § Paper
I-SR = Industrial-Synthetic Rubber
M = Municipal
(b) - Conventional 02 treatment plus
black liquor oxidation
(d) = Conventional 0^ treatment plus
sludge digestion
aerobic
§MAROX = FMC Corp.
OASES = Air Products § Chemicals, Inc.
UNOX = Union Carbide Corp.
(A) = Surface aerators (with or without
bottom mixers)
(F) = Fixed active diffusers
(R) = Rotating active diffusers
(T) = Submerged turbines
^CRYO = On-site liquid oxygen gas
generation
LIQ = On-site liquid oxygen storage and
vaporization
PIPE = Pipeline transport of oxygen gas
from a nearby off-site oxygen
generating facility
PSA = On-site pressure swing adsorption
oxygen gas generation
**n.d. = no data.
542
-------
APPENDIX B. OXYGEN-ACTIVATED SLUDGE PLANTS UNDER
CONSTRUCITON AS OF JUNE 1976
Location
Design
Flow
(mgd)*
Installed
02 Supply
Capacity
(tons/day)t
02 Dis- 02
Appli- solution Supply
cation^: Systems System1*
USA
1. Appleton Papers Div. of N.C.F.
Appleton, Wise.
2. Baltimore, Md.
3. Baton Rouge, La.
4. Broken Arrow, Okla.
5. Cedar Rapids, Iowa
6. Chicopee, Mass.
7. Cincinnati, Ohio
8. Crown Zellerbach Corp.
Antioch, Calif.
9. Dade County (North), Fla.
10. Danville, Va.
11. Denver (#1), Colo.
12. Detroit (#2), Mich.
13. Dow Chemical Co. Plaquemine, La.
14. Dubuque, Iowa
15. Duluth, Minn.
16. East Bay Municipal Utility District
(#1) - Oakland, Calif.
17. East Bay Municipal Utility District
(#2) - Oakland, Calif.
18. Euclid, Ohio
19. Exon Chemical Co. - Baton Rouge, La.
20. Fairbanks, Alaska
21. Fond du Lac, Wise.
22. Ft. Lauderdale, Fla.
23. Harrisburg, Pa.
24. Hillsboro, Ore.
25. Hopewell, Va.
26. Hot Springs, Ark.
27. Jacksonville (#2), Fla.
28. Kittanning, Pa.
29. Lewisville, Tex.
30. Littleton/Englewood, Colo.
31. Longview Fiber Longview, Wash.
32. Louisville, Ky.
33. Loxahatchee, Fla.
34. Mahoning County, Ohio
35. Miami, Fla
36. Middlesex, N.J.
37. Minneapolis, Minn.
38. Mobile, Ala
39. Mosinee Paper Corp. - Mosinee, Wise.
40. Muscacine, Iowa
41. Nekoosa Papers, Inc. - Port
Edwards, Wise.
42. New Orleans, La.
43. North San Mateo, Calif.
44. Pensacola, Fla.
45. Philadelphia (Southwest), Pa.
46. Pima County, Ariz.
6.5
1.5
14
1.5
I-PP UNOX (A) PSA
70
16
4
33
15.5
1.2
5.5
60
24
72
600
12.7
16
43.6
120
75
12
3.5
120
17
50
10
100
33
80
450
69
26
80
250
M
M
M(d)
M
M
M(Z)
I-PP
M
M
M
M
I-C
M
M
M
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
OASES (A)
UNOX (A)
UNOX (A)
OASES (T£A)
UNOX (A)
OASES (A)
UNOX (A)
UNOX (T)
CRYO
PSA
LIQ
CRYO
PSA
CRYO
PSA
CRYO
PSA
CRYO
CRYO
PIPE
CRYO
CRYO
CRYO
MAROX (R) PIPE
22
9
8
11
22
35.4
15
57.63
12.1
5
1.5
6
20
30
105
4
4
55
120
1
28
6
13
35
122
8
24
210
25
28
35
13
26
55
50
9
100
11.5
16
1
7
21
40
100
9
7
80
450
1
26
13
80
52.8
140
10
40
90
22
M
I-PC
M(d)
M
M(n)
M
M
M
M
M
M
M
M
I-PP
M
M(n)
M(n)
M
M(d)
M
M
I-PP
M
I-PP(b)
M
M
M(n50)
M
M
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
OASES (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
MAROX (R)
UNOX (A)
UNOX (T)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (T)
MAROX (F)
UNOX (A)
UNOX (A)
UNOX (A)
UNOX (A)
OASES (A)
UNOX (A)
OASES (A)
UNOX (A)
UNOX (A)
PSA
CRYO
PSA
PSA
CRYO
CRYO
PSA
CRYO
PSA
PSA
PIPE
PSA
CRYO
CRYO
CRYO
PSA
PSA
CRYO
CRYO
LIQ
PSA
PSA
CRYO
CRYO
CRYO
PSA
CRYO
CRYO
PSA
543
-------
r\L 1 J_.11 J./ J. J\. LJ y ^_iV^llt,_LlH^n-«vJ. — ^^_
Installed
Design 02 Supply 02 Dis- °2
Flow Capacity Appli- solution Supply
Location .
47. St. Regis Paper Co. Tacoma, Wash
48. Salem, Ore.
49. Shell Oil Co. - Norco, La.
50. Springfield, Mo.
51. Sunkist Growers, Lemon Products
Div. Corona, Calif.
52. Tahoe/Truckee, Calif.
53. Tampa, Fla.
i f
54. Tauton, Mass.
55. Thilmany Pulp § Paper Co.
Kaukauna, Wise
56. Tonawanda, N.Y.
57. Two Bridges, N.J.
TOTAL
Mexico
1. Fundidora Steel Co. Monterrey
Europe
1. ARA BIRS II, Switzerland
2. Bayer-Elberfeld Dusseldorf,
Germany
3. Copenhagen, Denmark
4. Palmersford, England
5. Union Carbide Belgium Antwerp,
Belgium
TOTAL
Japan
1. Mitsubishi Chemical Industries
Kitakyushu City
2. Mitsui Toatsu Chemicals
Takaishi City
3. Tokiwa Sangyo Owari Asahi City
TOTAL
*1 mgd = 0.044 cu m/sec
tl ton/day = 0.907 metric ton/day
tl-C = Industrial-Chemicals
I-DS = Industrial-Dyestruffs
I-FP = Industrial-Food Processing
I-PC = Industrial-Petrochemical
I-PP = Industrial-Pulp 5 Paper
I-S = Industrial-Steel
M - Municipal
(b) = Conventional 02 treatment plus
liquor oxidation
(mgd)* (tons/day) t cation* Systemi System*
34
26.5
4.3
30
1.75
8
51
8.4
22
30
7.5
2339.58
13.7
18
1.8
110
1.2
0.71
131.71
3.09
1.71
3.7
8.50
black
(d) = Conventional 02 treatment plus aerobic
sludge digestion
(n) = Conventional 02 treatment plus nitrification
(03) Conventional 02 treatment plus effluent
ozonation
(Z) = Treatment of Zimpro supernatant
only
40
36
50
36
50
4
120
20
10
32
6
3328.3
12.7
20
50
160
2
16
248
n.d.**
n.d.
n.d.
§MAROX
OASES
UNOX
(A) =
CF) =
CR) =
(T) =
<*CRYO
LIQ =
PIPE
PSA =
**n.d.
I-PP UNOX (A) CRYO
M UNOX (A) PSA
I-PC UNOX (A) CRYO
M(03) UNOX (A) PSA
I-FP UNOX (A) CRYO
M UNOX (A) PSA
M(n) UNOX (A) CRYO
M(n) UNOX (A) CRYO
I-PP UNOX (A) PSA
M UNOX (A) CRYO
M UNOX (A) PSA
I-S UNOX (A) PIPE
M UNOX (A) PSA
I-C UNOX (A) CRYO
M UNOX (A) CRYO
M(n) UNOX (A) PSA
I-C UNOX (A) PSA
I-DS UNOX (A) n.d.**
I-PC UNOX (A) n.d.
I-PP UNOX (A) n.d.
= FMC Corp.
= Air Products 5 Chemicals, Inc.
= Union Carbide Corp.
Surface aerators (with or
without bottom mixers)
Fixed active diffusers
Rotating active diffusers
Submerged turbines
= On-site cryogenic oxygen gas
generation
On-site liquid oxygen storage
and vaporization
= Pipeline transport of oxygen
gas from a nearby off-site
oxygen generating facility
On-site pressure swing adsorption
oxygen gas generation
= no data
544
-------
APPENDIX C. OXYGEN-ACTIVATED SLUDGE PLANTS
BEING DESIGNED AS OF JUNE 1976
1.
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.
Location
USA
Amherst, N.Y.
Augusta, Me.
Baldwinsville, N.Y. ,
Clay, N.Y.
Clinton, N.C.
Concord, N.C.
Dade County (South), Fla.
Easton, Pa.
Greenville, S. C.
Hamburg (South Towns), N.Y.
Hampton Roads Sanitary District, Va.
(a) Army Base
(b) Atlantic
(c) Boat Harbor
(d) Lamberts Point
Hannibal , Mo .
Holyoke, Mass.
Houston, Tex.
Indianapolis (Belmont) , Ind.
Indianapolis (Southport) , Ind.
Kansas City, Kan.
Kaukauna, Wise.
Lebanon, Pa.
Los Angeles (Hyperion) , Calif.
Los Angeles County (JWPCP) , Calif.
Maryland City, Md.
Montgomery County, Pa.
Monticello, N.Y.
Murfreesboro, Tern.
New Rochelle, N.Y.
Orlando, Fla.
Passaic Valley, N.J.
Philadelphia (Northeast), Pa.
Philadelphia (Southeast), Pa.
Red Springs, N.C.
Sacramento, Calif.
San Francisco, Calif.
South Cobb County, Ga.
Sussex County, Del.
Tri-Municipal Sanitary District -
Poughkeepsie, N.Y.
York, Pa.
Texas City, Tex.
TOTAL
Design
Flow
(mgd)*
24
8
9
10
3
25
40
10
5
12
19
36
26
37
4.25
22
200
125
125
54
6.1
8
330
500
4
10
6
8
14
24
300
150
100
1.5
150
180
24
8
14
8
7.5
2647.35
Design
C>2 Supply
Capacity
(tons/day) t
40
9
19
10
9
80
130
14
8
14
21
40
30
42
9
22
305
180
180
80
13
24
340
500
7
14
6
13
16
50
1000
100
80
5
200
100
40
11
9
13
11
3794
Appli-
cationt
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
* 1 mgd = 0.044 cu m/sec
t 1 ton/day = 0.907 metric ton/day
* M = Municipal
545
-------
CURRENT RESEARCH RELATED TO HEAT CONDITIONING OF WASTEWATER SLUDGE
B. V. Salotto, J. B. Parrel1, J. E. Smith, Jr., E. Grossman, III
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
ABSTRACT
Low and high temperature heat treatment of sludge produce liquors which are easily
dewatered but create other problems. High temperature - high pressure processes are
costly, energy intensive, and less safe to operate than are low temperature processes.
However, low-temperature processes produce liquors which need further treatment and they
add to the overall cost of the heat treatment process. Current research is aimed at
finding economical, energy-saving, processes to treat and recycle heat treatment liquor.
It is also aimed at developing heat treatment processes which are less energy intensive
but attain the same degree of oxidation as occurs in a high temperature heat treatment
process. In the first case laboratory conventional anaerobic treatment of the liquor has
been found to be a satisfactory method of treatment under low loading conditions; however,
a limiting factor is the liquid throughput rate. Data from operation of 3 lab digesters
indicate that at solids retention times of less than 10 days, some provisions must be made
for return of biomass to the system, otherwise washout may occur. Data are also presented
which would seem to indicate a new and novel approach to low temperature heat treatment
of sludge. It is known as the Puretec WETOX process. Pilot plant results indicate the
achievement of high oxidation rates equivalent to high temperature-high pressure, heat
treatment systems. Other advantages are claimed such as potential for heat and byproduct
recoveries.
INTRODUCTION
One of the most controversial processes
being employed in the wastewater treatment
industry today is that of thermal sludge
conditioning. The application of heat under
pressure (300 to 500°F and 150-400 psig) for
protracted periods conditions the sludge by
causing profound changes in its nature and
composition. Sewage sludges are essentially
cellular material containing intracellular
gel and extracellular zoogleal slime of
equal amounts of carbohydrate and protein.
The action of heat is to break open the
cells and release the mainly proteinaceous
protoplasm. The heat also breaks down the
protein and zoogleal slime, producing a
dark brown liquor consisting of soluble
polypeptides, ammonia nitrogen, volatile
acids and carbohydrates (1). Generally,
the end results of this conditioning and
"pressure cooking" step are a heat treated
sludge liquor which requires some sort of
handling and a residue of considerably
increased dewaterability. The magnitude
of these two effects is the subject of a
large amount of debate. The purveyors of
heat conditioning equipment claim that
after conditioning virtually no chemical
conditioning of the sludge is required for
dewatering, that it dewaters at a very high
rate, and that the cake solids produced
are sufficient to permit autogenous
incineration with recovery of sufficient
waste heat to drive the heat conditioning
process. Further they claim little dif-
ficulty in handling the heat treated sludge
liquor. The critics of heat treatment
disagree with all these claims and note the
following reported analyses of cooking
liquor: (2)
546
-------
BOD5 = 5000 to 15000 mg/1
COD = 10000 to 30000 mg/1
Ammonia = 500 to 700 mg/1
Phosphorus = 150 to 200 mg/1
About 20 to 30% of the liquor's COD has been
found not biodegradable in a thirty-day
period. While the volume of cooking liquor
from an activated sludge plant will amount
to 0.75 to 1.0% of the wastewater flow; on a
BOD and solids loading basis, the liquor can
represent from 30 to 50% of the normal
loading on the aeration system from settled
sewage. The critics also point to the
mechanical and odor problems that have oc-
curred at plants like Colorado Springs,
Colorado; Chattanooga, Tennessee; and
Speedway, Indiana. Then some plants like
Kalamazoo, Michigan, have found that the
costs of heat treatment have rapidly
escalated and treatment schemes had to be
installed to handle the processes' liquor.
It is possible by operating at even
higher temperatures and pressures in the
presence of oxygen to accomplish a high
level of organic destruction by the process
of wet air oxidation. Operating conditions
range from 450 to 600°F and from 800 to
1800 psig depending upon the degree of
oxidation required. This process normally
does not require external heating for
sustaining combustion once it is started.
Equipment includes grinders, high pressure
pumps, heat exchangers, high pressure react-
ors and separators. The end products of
wet air oxidation processes are a carbona-
ceous ash and sludge liquor. Criticisms of
this process are similar to those of the
low pressure and low temperature system but
include safety along with serious operating
and maintenance difficulties. The pollutant
concentration of the resultant cooking
liquor stream varies according to the degree
of treatment and the particular sludge
involved. Typical concentrations are: (3)
COD = 10000 to 20000 mg/1
BOD < 14000 mg/1
Ammonia = 500 to 1000 mg/1
Solids 5 2.5%
PH = 4 to 4.8
Because of the controversy surrounding
the two thermal sludge processes, EPA has
been conducting research to further
characterize heat treated sludge liquor
and evaluate methods for treating it. This
paper will report on these efforts. Further
the paper will report on a new wet air
oxidation process, which seeks to eliminate
some of the disadvantages of the older
system. This new process may also
facilitate the recovery of metals from
sludge. As such the types and quantities
of metals in sludge will be discussed
along with the feasibility of their
recovery.
LIQUOR FROM LOW TEMPERATURE
(< 400°F) HEAT TREATMENT
Anaerobic Treatment
Probably the major disadvantage of
heat treatment of sludge is the concen-
trated supernatant that is produced. If
the BOD discharged from a wastewater
treatment plant is not to be increased,
more treatment capacity is needed. For
the activated sludge process, this means
a larger aeration basin, greater air
demand, and more biological sludge to be
processed. An alternative approach is to
treat the sludge anaerobically. Anaerobic
treatment reduces BOD with a much smaller
increase in biomass than occurs with
aerobic treatment, no power cost for air
compression is incurred, and usable fuel
gas is produced. Treatment can be carried
out by using conventional anaerobic
digestion or an anaerobic filter (4).
Both of these methods have advantages.
Since most plants that are using heat
treatment previously used digestion,
digesters are generally available for use.
The anaerobic filter is probably the
better choice if new construction is
required. Research has been commenced in
our laboratory on both of these approaches,
but only the anaerobic digestion approach
is far enough along for presentation of
preliminary results.
In order to measure such things as
gas production and COD destruction under
different loading conditions, three small
laboratory anaerobic digesters were set
up, each containing 3.5 liters of digesting
material in a 4 liter digesting bottle.
Figure 1 shows a schematic picture of one
of the digesters. Provision was made to
maintain temperature constant, to stir the
contents of the digester with a magnetic
stirrer, and to collect and measure each
day's production of gas. Not shown in the
figure is a gas analyzer apparatus to
measure C02 content of the gas mixture.
547
-------
Data were collected so as to be able to
determine or calculate such items as load-
ing rates, COD, BOD, volatile solids
destruction and gas yield.
At first all three digesters were fed
150 ml of heat treatment liquor each day
for 12 weeks. Thus, all three digesters
were operated at the same loading rate.
A supply of heat treatment liquor was
obtained from a local sewage treatment
plant which heat treated its sludge by the
low pressure Zimpro process. Each day
150 ml of digesting liquor was removed
from each digester and analyzed for COD,
BOD, total and volatile solids, pH, and
Thermometer
Inlet
Heating
Tape
\ Magnetic
\ S t i r r e r
Figure 1. Bench Scale Anaerobic Digester.
548
-------
the like. The hydraulic detention time for
all three digesters was 24 days.
The manner of withdrawing digesting
liquor is of interest. In all cases, the
digester was thoroughly mixed just before
the withdrawal was made. This procedure
is equivalent to the withdrawal method
used for conventional sludge digestion.
A portion of the active biomass is with-
drawn with the digesting liquor. This
procedure is suitable provided the
residence time in the digester is high
enough so that "washout" of the biomass
does not occur. It may be possible to
push anaerobic digestion of supernatant to
very high rates if biomass is returned to
the digester, or is not removed by allow-
ing settling before withdrawal. This
latter procedure will be tested in a later
phase of the investigation.
Some preliminary results of the
digester study have been obtained. Table 1
lists average characteristics of the heat
treatment liquor feed. It should be
pointed out that the more settleable solids
were allowed to settle and the supernatant
stored before feeding the digesters. This
was done so that the liquor might more
nearly resemble the filtrate derived from
vacuum filtration of a heat treated sludge.
TABLE 1
AVERAGE CHARACTERISTICS OF HEAT TREATMENT
LIQUOR FEED (TO ANAEROBIC DIGESTERS)
PARAMETER
pH
ALKALINITY
TOTAL SOLIDS
VOLATILE SOLIDS
COD
BOD
TKN
NH3
VOLATILE ACIDS
PHOSPHORUS
UNIT
pH Unit
mg/1 CaCO,
mg/1
mg/1
mg/1
mg/1
mg/1 ACETIC
mg/1
AMOUNT
5.6
640
0.55
79
6200
2440
590
240
1340
40
As the data indicates, the percent total
solids is low (0.55%). Note that the pH is
low as is the alkalinity. This was of some
concern because in normal digestion these
values are higher. As might be expected,
COD and BOD are high although heat treat-
ment liquors are often much higher. The
nitrogen and phosphorus values are shown
to indicate that these essential nutrients
are present in sufficient amounts to insure
good digestion.
Data for all 3 digesters operating at
the same loading rate were so similar that
the tabulation shown in Table 2 is typical
of all 3 digesters. This simply indicates
that very little variation occurred. The
excellent agreement of results among the
three digesters gives confidence that
differences in performance noted in later
tests when operating parameters for the
digesters are different will be the effect
of the changed conditions and not lack of
reproducibility within the units.
TABLE 2
DIGESTER OPERATION: OPERATING PARAMETERS
AND ANALYSES OF DIGESTED LIQUOR*
OPERATOR UNIT AMOUNT
FEED RATE ml/day 150
pH pH Unit 7.0
ALKALINITY mg/1 CaCOj 1910
VOLATILE ACIDS mg/1 ACETIC 63
TEMPERATURE °C 33+0.2
TOTAL SOLIDS % 0.33
VOLATILE SOLIDS % 54.5
COD/BOD mg/1 2160/220
DETENTION TIME DAYS 24
LOADING RATE, VS Kg/m /day 0.174
VOLATILE SOLIDS REDUCTION °, 59
GAS YIELD, PER
VOLATILE SOLIDS DESTROYED m gas/Kg VS DESTROYED 0.95
VOLATILE SOLIDS ADDED m3gas/Kg VS ADDED 0.62
'Average results of three digesters
A comparison of the analyses of the
feed (Table 1) and the product (Table 2)
shows that pH increased to a normal value
of 7.0, alkalinity increased to 1900 mg/1,
and volatile acids dropped to a low value.
These data show a good operating digester.
Variations of the properties of the digested
liquor with time are presented in Figure 2.
As can be seen, pH was quite stable around
7, whereas alkalinity and volatile acids
fluctuated somewhat during the 12 week
period.
549
-------
_ 1900--
5 1700--
-1500
LOADING RATE: 0.17 Kg VS/m3/DAY
DETENTION TIME: 24 DAYS
TIME, WEEKS
O
<
I
Figure 2. Characteristics of Digested Heat
Treatment Liquor- Unit 1.
During the last 12 week phase of the
study, each digester was operated at dif-
ferent loading rates in which 300 ml,
450 ml, and 600 ml of heat treatment liquor
was fed daily to the 3 digesters. Un-
fortunately, an accident occurred with the
digester being fed 600 ml of liquor per day
so that no data can be presented for that
digester. Table 3 shows results of digest-
er operation at the 300 and 450 ml feed rate
after a run of 12 weeks compared with
operation of 150 ml for the other 12 week
period. Note that efficiency of the
anaerobic process decreases as the loading
rate increases. Less COD, BOD, or volatile
solids are being destroyed as the loading
rate increases. Note also that gas yield,
% C02, and volatile acids change with
changing loading rate. Surprisingly, no
adjustment of pH or addition of alkalinity
was needed for digester operation.
Alkalinity built up to approximately
3000 mg/1 at the higher rates.
These studies will continue at higher
loading rates to determine at what point
digester failure occurs. Comparisons will
be made against operation in which biomass
is retained in the digester, to determine
the increase in throughput rate that can be
achieved with this mode of operation.
Aerobic and Physical-Chemical Treatment
Studies in Great Britain have indicat-
ed that heat treatment liquor can be
TABLE 3
DIGESTER OPERATION AT DIFFERENT LOADING RATE
(DIGESTED SUPERNATANT)
LOADING RATES, ml/DAY
OPERATOR
pH
ALKALINITY, mg/I
TOTAL SOLIDS, °-i
VOLATILE SOLIDS, %
COD, mg/1
BOD, mg/1
DETENTION TIME, DAYS
VOLATILE SOLIDS LOADING, Kg/m3/day
COD/BOD REDUCTION, %
GAS YIELD
m3gas/Kg VS DESTROYED
m3gas/Kg VS ADDED
% C02 GAS MIXTURE
VOLATILE ACIDS, mg/1
150
7.0
1910
0.33
54
2160
222
24
0.174
65/91
0.95
0.62
22
63
300
7.2
3310
0.40
61
3600
660
12
0.657
68/87
0.82
0.52
28
114
450
7.1
3130
0.44
64
4510
1040
8
0.985
60/80
0.61
0.39
29
410
reduced in BOD by the activated sludge
process and by trickling filters. Corrie,
in a relatively recent publication (2),
reports considerable success in which
treatment by the activated sludge process
is followed by adsorption on activated
carbon. By this procedure both BOD and COD
are reduced. Typically, biological
processes are not very effective in reduc-
ing the COD of heat treatment liquors.
Corrie's procedure will be evaluated at
Lake County, Ohio, where a heat treatment
unit has been installed under an EPA grant
(5). At Lake County, the effectiveness of
high lime treatment of heat treatment
liquor will also be evaluated. Unfortunate-
ly, these studies have not been commenced
as yet because of unusual difficulties
encountered in starting up the heat treat-
ment unit.
A NEW APPROACH TO HIGH TEMPERATURE OXIDATIVE
SLUDGE PROCESSING
Puretec Wet Oxidation Process
Oxidation of water-based sludges at
high temperatures in the presence of air
was pioneered by the Zimpro Division of
Sterling Drug. Although several instal-
lations were made (e.g., Chicago, Wheeling,
Akron), Zimpro has had its greatest com-
mercial success with low oxidation units
(<400°F). The primary disadvantage of the
high temperature units has been the high
temperature (>500°F) and high pressure
(ca. 1600 psi) conditions of operation.
550
-------
In the Zimpro process, air and sludge
are admixed and pumped through a vertical
unmixed reactor. Numerous studies have
indicated (6) that agitation improves
reaction rate of multiphase processes.
However, mechanical problems for stirring
high pressure reactors are formidable.
The Resource Recovery Systems Division of
the Barber-Colman Company has developed a
processing system, the Puretec Process,
and equipment that seems to overcome these
difficulties. Operating temperatures are
about 450°F and pressures about 600 psi.
The U.S. EPA is financing a grant to the
City of Philadelphia to investigate the
Puretec Process at their Northeast
Wastewater Treatment Plant on a sufficient-
ly large scale to accurately determine
process costs, claimed heat recovery
benefits, and achievable sludge destruc-
tion. (7)
The Philadelphia Puretec Installation
The Puretec WETOX unit, Model 6-54,
can treat a sludge flow of 3000 gallons per
hour or 16 tons of dry solids per day.(8)
In the process, oxidation of liquid
waste is carried out continuously at 430°F
and 600 psig in an acidic medium
(3 g/1 H2S04). The oxidation proceeds in
a horizontal autoclave containing 6 com-
partments with individual stirring in each
compartment. A process flow diagram is
shown in Figure 3. Macerated sludge is
pumped through a liquid and vapor phase
tube-in-tube heat exchanger and into the
front end of the reactor. The sludge is
mixed with compressed air, and reacted in
the first chamber from which it overflows
successively into the several following
compartments undergoing nearly complete
oxidation. Acid addition as well as stir-
ring enables a high rate of oxygen transfer
to the sludge causing a rapid destruction
of organic matter. Sulfur compounds are
oxidized to sulfates. In the final com-
partment liquid and vapor phases are
separated and conducted separately to heat
exchangers for thermal energy exchange with
incoming sludge. After cooling the vapor
phase and the liquid phase are let down to
atmospheric pressure. At this point a
variety of post-treatment steps may be used
to purify the effluent side-streams such as
the lime treatment step shown in Figure 3.
Pilot Plant Results at Irvine, California
Some impressive results have been
achieved with the 4-10 model, 20 gallon/hr
pilot plant Puretec unit at Irvine,
California, the location of the Barber-
Colman Company Research Lab. Figure 4
shows good improvement in COD reduction
versus speed of agitation. Note that at
high rpm after a reaction time of 40
minutes one obtains an 80 percent reduction
in COD. Figure 5 shows the increase in
COD destruction as a function of acid
VAPOR EFFLUENT
RAW
SEWAGE
SLUDGE
MACERATOR
LET-DOWNC
NEUTRALIZER
pH 7
CLARIFIER
LIQUID PHASE
HEAT f
EXCHANGER f
LJUUUt
LIQUID EFFLUENT
VAPOUR
PHASE HEAT
EXCHANGER
LIME FEED
TO PRIMARY
TREATMENT
M in in
WETOX REACTOR
TO PRIMARY
TREATMINT
NEUTRALIZER
pH 7
CLARIFIER
FILTER
CLARIFIER
NEUTRALIZER STERILE
pH 10.5-11 SOLIDS
BOILER:
START UP
ONLY
COMPRESSOR
LIME RECOVERY PROCESSOR
TO LIME FEED
Figure 3. Process Flowsheet of the Wetox Unit. A Lime Treatment System is added on to Further Purify
the Wetox Effluents. The Combined System (Wetox Plus Lime Treatment) is Registered Under
the Trade Name of Puretec System.
551
-------
Q
O
VJ
z
o
^-
u
o
uj
QC
h-
Z
LU
{J
80
70 —
60
50
40
30
20
10
X
I
U nagitated
250 rpm
A 750 rpm
Q] 1500 rpm
I
0 10 20 30 40 50 60
TIME AFTER INJECTION OF SLUDGE, MINUTES
Figure 4. Effect of Agitation in Wetox.
addition. The effect of the acid is to
shorten the reaction time. The usual dose
of 1^2864 is 3 g/l; higher doses, as shown
in Figure 5, do not materially affect the
reaction time.
Advantages Claimed for the Puretec Process
(8)
No scale or corrosion problems
corrosion is inhibited in the process by
250001-
<* 20000
01
E 15000
Q
O
u
10000
5000
OPERATING CONDITIONS 450°F - 600 psi
• 0 g/l H2SO4
X 3 9/1 H2SO4
O t> g/l H2SO4
15 30 45
TIME IN MINUTES
60
Figure 5. COD Reduction of Orange County
Sanitation District Primary Sludge.
using titanium in piping and valves and by
lining the inside of the reactor with lead
and acid-resistant brick. The chief ad-_
vantage here is that corrosion due to Cl
or SO^ ions is prevented. Acid also
prevents scaling in the reactor or in
piping.
No odor or noise problems the use of
adequately dispersed oxygen in an acidified
medium results in a rapid oxidation of
sulfur and nitrogen-bearing compounds to
sulfate and ammonia. The reaction does
not form the intermediate organic compounds
which tend to be malodorous in conventional
processes. Raw primary or unstabilized
sludge is ordinarily extremely offensive;
however, under the Puretec oxidizing
conditions very little odor is present.
Carefully muffled low speed compressors,
which supply the high pressure air,
specially designed high pressure sludge
pumps, and the design of the let down
valves all combine to minimize the noise
level usually associated with operation of
heat treatment units.
The Puretec WETOX process is com-
petitive analysis of costs of the process
indicate a figure of $45-50 per ton of dry
solids; this cost has not been adjusted by
credits as a result of by-product recover-
ies. Adjustment downward as a result of
credits could materially lower the overall
cost of sludge treatment and disposal.
FEASIBILITY OF METALS RECOVERY
Concentration of Metals in Sludge
Before recovery of metals can be
discussed, it is important to establish
concentration levels in order to determine
whether recovery is feasible. It is well
to note that quantities to be processed and
concentrations can be well below the normal
levels considered to be practical for metal
refining operations, because there is a
credit to be taken for reduction of
potential hazard and disposal costs of the
residue.
Fortunately, considerable information
has been collected on the concentrations
of metals in sludge. The Ultimate Disposal
Section of the Municipal Environmental
Research Laboratory's Wastewater Research
Division in Cincinnati has had an ongoing
program in which sludges from various
treatment plants around the United States
552
-------
are analyzed. Results have been published
by Salotto et al (9). Average con-
centrations of 13 metals are shown in
Table 4. It can be noted in Table 4 that
the geometric mean is closer to the median
value than the arithmetic mean. This
indicates that a logarithmic mean distribu-
tion is a good estimate of the type of
distribution of metal concentrations. This
in fact is the case for all metals examined,
and is illustrated by data for zinc in
Figure 6. The implication of a logarithmic
mean distribution, when coupled with a
large logarithmic standard deviation or
"spread", is that there will be a fairly
large number of plants with concentrations
substantially in excess of the median.
This indicates that the median concentra-
tion is probably too low a figure to use in
estimating the practicality of recovery,
but a number substantially higher should be
used.
.400-.
TABLE 4 (See Reference
AVERAGE CONCENTRATIONS OF METALS
IK DIGESTED SLUDGE
(ALL FIGURES MS/KG* DRY SLUDGE BASIS)
>-
u
Z .300-
^U
D
O
LU
Of
LL.
.200-
LU
>
1—
<
_J
^ -100-
2.25 2.55 2.85 3.15 3.45 3.75 4.05 4.35
LOG Q PPM CONCENTRATION
Figure 6. Histogram of Zinc in Digested Sludge.
Metal Recovery by the Puretec WETOX Process
As mentioned earlier, because of the
use of sulfuric acid in the Puretec WETOX
process, the potential for metal recovery
looks quite good. Dr. W. Martin Fassell,
vice-president and developer of the
process, in his article "Sewage Sludge at
a Profit" (10), has reported on tests by
Barber-Colman on recovery of metals from
ash after wet-oxidation. The effect on
the original level of acid addition on the
percent of the metal remaining in sludge
METAL
SILVER
BORON
CADMIUM
CALCIUM
CHROMIUM
COBALT
COPPER
MERCURY
MANGANESE
NICKEL
LEAD
STRONTIUM
ZINC
ARITHMETIC
MEAN STD.DEV.
+
250 230
!+30 310
75 10U
36,500 23,800
1,860 1,920
350 220
1,590 1,670
10 18
1,300 2,290
680 620
2,750 2,350
520 670
I*, 210 3,600
I
GEOMETRIC
MEAN STD.DEV.
t X
190
380
1*3
31,100
1,050
290
1,270
1.99
1.58
2.1*7
1.77
3.22
1.88
1.95
6.51 2-3<*
1*75
530
2,210
290
2,900
3.67
1.88
1.82
2.70
2.1(O
MEDIAN
yyf>
VALUE
100
350
31
30,000
1,100
< 100
1,230
6.6
380
1*10
830
175
2,780
* A MG/KG PPM.
< LESS THAN
treated by the Puretec process is shown in
Table 5. It is interesting to observe
from these data that increasing amounts of
acid did not necessarily dissolve more of
the metals, in fact, very little lead,
silver and titanium were dissolved out of
the ash. Evidently the ion products of
insoluble forms of these elements were
sufficiently low that dissolution was not
possible. On the other hand, copper,
cadmium, and zinc are quite soluble, and
afterwards can easily be recovered by
precipitation as sulfides according to the
claim of Dr. Fassell (10). At any rate,
it would seem, because of the presence of
an acid side effluent, that the potential
for metal recovery is quite good.
TABLC 5 (See Reference 10)
PERCENT Of METALS PRESENT TN
WET OXIDATION ASH VERSUS ACID ADDITION
METALS
WT.%
COPPER
LEAD
ZINC
CADMIUM
SILVER
IRON
TITANIUM
PH
H SO ADDITION TO SLUDGE FEED
GRAMS PER LITER
0
93
100
100
97
98
98
100
5.0
6
66
90
66
50
94
91
100
3.5
12
53
77
44
38
87
92
100
1.8
18
7
77
0
0
88
65
100
1.1
553
-------
SUMMARY
Low pressure heat treatment, a sludge-
conditioning process that has seen almost
explosive adoption by wastewater treatment
plants in the United States, solves the
sludge dewatering problem in most cases,
but creates nearly as many problems as it
solves. One of its serious drawbacks is
the creation of a concentrated recycle
liquor. It is anticipated that there will
frequently be a need to separately treat
this concentrated liquor to reduce the load
on the treatment plant. Aerobic and
physical-chemical means have been demon-
strated to be effective for separate
treatment but they are costly and require
manpower to operate. Anaerobic processes
are worth considering as an alternative
because they are typically less labor and
power intensive. The present investigation
demonstrates that conventional digestion
satisfactorily reduces BOD of heat treat-
ment liquor. Continuing studies will be
directed towards achieving higher treatment
rates by modified anaerobic digestion by
recycling biomass, and by the anaerobic
filter.
High temperature oxidative processes
for sludge disposal have been poorly ac-
cepted because of cost and extreme
processing temperatures and pressures.
The Puretec process claims to avoid these
extremes by use of a stirred reactor, for
which high contact efficiency is claimed.
A demonstration at the City of Philadelphia,
sufficiently large to demonstrate economics
of performance, will be carried out with
EPA support. The unique configuration of
the reactor and the use of acidic con-
ditions offers the possibility of recovery
of heat, byproduct streams such as ammonia
and acetic acid and some metals.
ACKNOWLEDGEMENT
The authors wish to acknowledge
Mrs. Patricia Tutt, Physical Science Aid,
for her very valuable assistance in the
anaerobic digester study of heat treatment
liquor. We also wish to acknowledge the
help of Dr. W. Martin Fassell, Vice-
President, Barber-Colman Company, who gave
us permission to use pilot plant data and
loaned us slides for the presentation.
References
1. Brooks, R.B., "Heat Treatment of Sewage
Sludge," Water Pollution Control (G.B.)
69, 221 (1970).
2. Corrie, K.D., and Wycombe, R.D.C.,
"Use of Activated Carbon in the Treat-
ment of Heat Treatment Plant Liquor,"
Water Pollution Control (G.B.) 71, 629
(1972).
3. Fischer, W.J., and Swanwick, J.D.,
"High Temperature Treatment of Sewage
Sludges," Water Pollution Control (G.B.)
70_, 355 (1971).
4. McCarty, P.L., "Anaerobic Treatment of
Soluble Wastes" in Advances in Water
Quality Improvement, edited by Glazer
and Eckenfelder, University of Texas
Press, Austin (1968).
5. EPA Grant 11010 OKI, "Porteous Process
for Heat Treatment of Sludge," Grant
awarded to Lake County, Ohio, Sept.
1971. (Project officer, B.V. Salotto,
EPA, Municipal Environmental Research
Laboratory, Cincinnati, Ohio 45268).
6. Parrel1, J.B., and Haas, P.A.,
"Oxidation of Nuclear Grade Graphite
by Nitric Acid and Oxygen," IECC
Process Design and Development 6_, 277
(July 1967).
7. EPA Grant S-803644-01-1, "Puretec
Wet-Oxidation of Municipal Sludge,"
Grant awarded to the Philadelphia Water
Department, Philadelphia, Pennsylvania,
May 30, 1975. (Project officer,
B.V. Salotto, EPA, Municipal Environ-
mental Research Laboratory, Cincinnati,
Ohio 45268).
8. Seto, P., "Evaluation of the Barber-
Colman WETOX Process for Sewage Sludge
Disposal," Training and Technology
Transfer Division (Water), EPS,
Ottawa, Canada, KIA OH3, Project No.
73-5-6, May 1975.
9. Salotto, B.V., Grossman, E., and
Farrell, J.B., "Elemental Analysis of
Wastewater Sludges from 33 Wastewater
Treatment Plants in the United States,"
in Pretreatment and Ultimate Disposal
of Wastewater Solids, Rutgers
University, May 21-22, 1974, EPA
Report No. 902/9-74-002.
10. Fassell, M., "Sludge Disposal at a
Profit?" Municipal Sludge Management,
Barber-Colman Company, 1882 McGaw Ave.,
Irvine, California 92705.
554
-------
EPA's RESEARCH PROGRAM IN SEWAGE SLUDGE COMBUSTION
R. A. Olexsey
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
ABSTRACT
EPA's research program in the area of thermal decomposition of sewage sludges ad-
dresses the problems of increased sludge production, energy shortages, pollutant emissions,
and cost. In the current fiscal year, EPA is supporting a number of projects in the areas
of conventional incineration, starved-air incineration, and pyrolysis. The purpose, ap-
proach, and any significant results achieved to date are discussed for each of the major
ongoing projects in the area of sludge combustion and pyrolysis. Pre-fiscal 1976 projects
described include an engineering feasibility study on techniques for combined incineration
of solid wastes and sludges, a full scale research investigation of incineration of sludge
with coal, a pilot plant study of sewage sludge pyrolysis, and a full-scale demonstration
of oxygen-enriched starved-air incineration. Projects tentatively planned for the fiscal
1976 and 1977 program years are outlined and briefly described.
INTRODUCTION
EPA's research program in sewage
sludge combustion is directed toward the
development of environmentally acceptable
and cost effective alternatives to ocean
disposal, which is no longer considered
appropriate, and direct land disposal, which
is not always economically or politically
feasible. Table 1 outlines the projected
growth of incineration as a sludge disposal
medium based on current trends toward on-
site disposal (1). Because of a number of
external forces exerting pressures on both
the sludge generation and sludge disposal
operations development of effective thermal
disposal techniques is not an easy task.
TABLE 1. TRENDS IN DISPOSAL OF SLUDGES
(WEIGHT PERCENT)
Disposal Methods
Landfill
Utilized on Land
Incineration or Pyrolysis
Ocean
(Dumping or Outfalls)
1972
40
20
25
15
1985
40
25
35
0
Foremost among the factors making mat-
ters difficult for sludge disposal is the
fact that mandated Federal discharge stan-
dards require secondary treatment by 1977
and no pollutant discharge by 1985 (2).
While the implementation of these standards
will result in substantial improvements in
water quality, an unfortunate by-product
will be the production of much larger quan-
tities of much wetter, more difficult to
dewater sludge. Table 2 describes this ex-
pected growth in sludge generation (1).
TABLE 2. TRENDS IN PRODUCTION OF SLUDGES
1972 1985
Sludge Type
Primary
Secondary
Chemical
Totals
Pop.
(Mill.)
145
101
10
Tons/Yr Pop.
(Mill.) (Mill.)
3.2 170
1.5 170
0.09 50
4.8
Tons/Yr
(Mill.)
3.7
2.5
0.5
6.7
The production of more and wetter
sludge impacts the second area of concern
in sludge combustion; that is, the increas-
ing cost and decreasing availability of the
auxiliary fuel required to sustain combus-
555
-------
tion in sludge burners. Table 3 describes
the effects of increased sludge cake mois-
ture contents on auxiliary fuel demand in a
multiple hearth furnace, with 800° F ex-
haust gas temperatures and 75 percent ex-
cess air (3). Thus, with current dewater-
ing and combustion practices, the trend
toward increased fuel consumption is di-
rectly counter to contemporary efforts at
fuel conservation.
TABLE 3. ENERGY REQUIREMENTS FOR SLUDGE CAKES
Cake BTU x 10 * BTU X 10 Gallons of *2
Moisture/ Lbs. Water BTU x 10 Provided bv Auxiliary Pud Oil for
Solids Per Ton Required for Sludge BTU Au.\. Req.
Ratio Dry Solids Evap.of Water Solids Ton Requirement Per Ion
95/5
90/10
85/15
80/20
75/25
70/30
65/35
* Assuming
Heating
38,000
18,000
11 ,333
8,000
6,000
4,667
3,71-1
volatile sol
value of void
97.00
45.95
28.95
20. 42
15.51
11.91
9.49
ids of dry
tile solids
14.70
14.70
14.70
14.70
14.70
14.70
14.70
sludge solids
= 10,500 BTU/
S2.30
31.25
14.23
5.72
0.61
Autogenous
Autogenous
= 701<
'lh volotilcs
572
217
99
40
A
Thirdly, air pollution emissions regu-
lations and enhanced public sensitivity to
air-quality and public health-environment
interaction tend to create a somewhat hos-
tile local atmosphere for incinerator
siting. Although an EPA task force on
sewage sludge incineration found that prop-
erly controlled well designed sludge in-
cinerators were not a significant source
of particulate emissions (4), attempts at
incinerator installation are often met by
vociferous public concern about such con-
siderations as heavy metal emissions and
microbiological aerosols.
Finally, the accelerating cost of in-
cineration is the essential consideration
in projecting the future for this option.
The following listing notes that incinera-
tion is a high cost disposal technique
relative to alternative means of disposal
(1973 costs) (5).
Total Costs
Method ($/Dry Ton)
1. Disposal as liquid soil
conditioner 20
2. Dewatered sludge as soil
conditioner 32
3. Heat drying 64
4. Lagooning 15
5. Landfilling dewatered sludge 32
6. Barging to sea 15
7. Pipeline to sea 14
8. Incineration 32
If combustion is to remain a viable
sludge elimination alternative, these
issues of capacity, fuel, public health and
cost must be squarely addressed. Toward
this end, the Wastewater Research Division
of the Municipal Environmental Research
Laboratory is conducting and supporting a
number of applied research, development,
and demonstration projects in the areas of
conventional incineration processes and
advanced techniques such as pyrolysis and
starved-air thermal degradation.
ONGOING RESEARCH
Currently, on a project by project
basis, the research program in sludge
combustion is divided roughly in half be-
tween efforts devoted to upgrading conven-
tional incineration and tasks oriented
toward development of new processes.
Project formats range from paper design
concept type studies to full-scale demon-
strations of processes that have been
proven successful in bench or pilot plant
testing.
Review of Coincineration Technology
Sewage sludge incinerators demand sup-
plemental fuel. Solid waste incinerators
most often produce excess heat. Because
of similarities in motivational circum-
stances, cities that practice solid waste
incineration often also incinerate sewage
sludge. Therefore, it would appear to be
a perfectly logical development that the
two materials be disposed of in a common
incineration process. Conceptually at
least, savings would result from decreased
auxiliary fuel demand, capital economies
of scale, and the need to operate only one
facility. Figure 1 is an extremely simpli-
fied schematic of a combined incineration
system. In this arrangement, hot flue
gases from a solid waste incinerator are
used to dry incoming sludge in a separate
chamber. The dried sludge is then burned
in the same furnace as the refuse.
In spite of the seemingly irrefutable
logic of combined disposal, the history of
coincineration in the U.S. had been a study
in failure. Facilities enjoyed only short
lives and were plagued by operational
problems and high costs. In short, co-
incineration, while relatively successful
in Europe, had simply not worked in the
United States.
556
-------
FAN
SOLID WASTE
COOLED GAS
G>
HOT FLUE GAS
SLUDGE CAKE
O
DRY SLUDGE
INCINERATOR
SLUDGE DRYER
Figure 1. Simplified system for combined incineration.
To analyze the failure of coincinera-
tion and suggest feasible alternatives,
the EPA, after competitive bidding, entered
into a contractual arrangement with the
Roy F. Weston Company of West Chester,
Pennsylvania. Under the terms of this con-
tract (EPA No. 68-03-0475), the contractor
would explore the literature, visit oper-
ating sites in both the U.S. and Europe,
and perform engineering feasibility studies
of specific techniques.
While the final results of this study
are not yet reported, some conclusions can
be drawn. Coincineration was not ap-
proached seriously in the U.S. when fuel
was abundant and cheap. Most coincinera-
tion facilities operated through simple
addition of sludge cake to the feed of a
solid waste incinerator. The high moisture
contents of sewage sludges require design
modifications to facilitate pre-drying of
the sludge feed. Often, the refuse itself
is too wet to burn without supplemental
fuel.
Some successes have been achieved. A
spray dryer-incinerator has operated inter-
mittently at Ansonia, Connecticut, and a
rotary dryer at Holyoke, Massachusetts, has
performed reasonably well. As can be ex-
pected from any paper type study, starved-
air incineration techniques ranked highly
in the Weston evaluation.
The final report for the study will
include design specifications for applica-
tion of the most promising techniques to
an existing sewage treatment plant. Cost
data will be provided and local factors,
such as geography and politics, which might
impact implementation of a combined dis-
posal system will be discussed.
Pulverized Coal as a Dewatering Aid
One solution to the fuel problem would
be the production of a sludge cake feed
that burns autogenously, that is, without
auxiliary fuel. This, of course, can be
accomplished by producing a cake that has
a moisture content that is low enough so
that the latent energy in the sludge solids
is sufficient to evaporate the moisture in
the cake. A second approach is to increase
the volatile content of the cake to a point
that the cake will support combustion.
Some previous EPA research work had
shown that incinerator ash could be of sig-
nificant value as a conditioning agent in
vacuum filtration operations (6). Filter
yield and cake solids content increased
substantially with ash dosages in the
range of from l-.O Ib. ash/lb. sludge solids
to 4.0 Ib. ash/lb. sludge solids.
While the addition of ash resulted in
improved filter performance, it also re-
duced the energy content of the sludge
557
-------
cake because of the increased presence of
inert material in the filter cake. An in-
house research project was initiated to
evaluate the performance of pulverized coal
as a filtration aid. If the coal did not
impair the function of the vacuum filter,
then the fuel value realized from the coal
addition could serve to allow the replace-
ment of costly fuel oil with the less ex-
pensive coal.
Table 4 compares the properties of the
coal and sludge used in the filtration
study (7). The coal used was mine run
Pennsylvania bituminous coal with a rela-
tively low sulfur content. The sludge was
a 1 to 1 by weight mixture of primary and
waste activated sludge.
TABLE 4. COMPARISON OF THERMAL PROPERTIES
Property
Coal
BTU/lb Dry Volatile
Solids
Volatile Solids %
BTU/lb Dry Solids
Sulfur %
14,200
93.6
13,300
0.60
10,500
65-75
7,370
0.60
Figure 2 emphasizes the enhancement of
sludge cake fuel value while the filter
yield and final cake solids increased mar-
ginally with coal fines addition (7). The
coal dosages monitored were in the range of
from 0.1 Ib. coal per Ib. of sludge solids
to 0.4 Ib. coal per Ib. of sludge solids.
Figure 3 describes the magnitude of
coal addition required to achieve autoge-
nous combustion conditions in a multiple
hearth furnace at two significant exhaust
gas temperatures (7). The range of addi-
tion of from 0.1 to 0.2 Ib. coal per Ib. of
sludge solids that provides the needed
energy represents significant economic sav-
ings over the conventional method of simple
filtration and oil addition. At current
prices, coal addition in the required range
can accomplish cost reductions of from $4
to $15 per ton of dry sludge solids incin-
erated (3,7) .
Further work is planned with coal and
ash mixtures as filtration aids. The pur-
pose of this work would be to reduce the
usage of conditioning agents such as lime
and ferric chloride.
4000
3000
2000
1000
0
£ 4
2
0
60
40
20
_ BTU'S/lb WATER
FILTER YIELD
7
CAKE SOLIDS
I
I
I
0.1 0.2 0.3 0.4
COAL DOSE (Ib COAL/lb DSS)
Figure 2. 'Coal performance.
BTU'S REQUIRED ]400°F
BTLTS REQUIRED @>800°F
I
I
02 0.3
0.5
COAL DOSE (Ib COAL/lb DRY SLUDGE SOLIDS)
Figure 3. Thermal profile coal conditioned sludge.
Full Scale Incineration with Admixes
To underscore the threat that the fuel
shortage poses to on-site sludge disposal
systems, EPA recently entered into a re-
search grant arrangement with the Metro-
politan Waste Control Commission of the
Twin Cities Area (Minneapolis-St. Paul).
Under the terms of this grant (EPA No.
R803927) a series of fuel admixes will be
combusted with the sewage sludge feed to
558
-------
the six dry tons per day multiple hearth
incinerators at the Commission's 24 mgd
Seneca Sewage Treatment Plant. The plant
is ideal in that the sludge disposal
system consists of two independent and
parallel lines, each including its own
vacuum filter, conveyors, feed apparatus,
and incinerator. One line will be used as
a control and one line will be used to
test the effects of the various admixes.
The incinerators at Seneca resemble the
model depicted in Figure 4.
COOLING AIR DISCHARGE
FLOATING DAMPER
SLUDGE INLET
J«g
FLUE GASES OUT
RABBLE ARM
AT EACH HEARTH
DRYING ZONE
COMBUSTION
AIR RETURN
COMBUSTION
ZONE
COOLING ZONE
RABBLE ARM
DRIVE
VCOOLING AIR FAN
Figure 4. Typical section: Multiple
Hearth Incinerator.
Tests of from one to four months' dura-
tion each will be conducted with various
fuel additives in place of the normally
used No. 2 fuel oil. Fuels will be lumped
coal mixed with filter cake, pulverized
coal mixed with liquid sludge prior to
filtration, shredded and classified com-
bustible solid waste, pelletized solid
waste, scrap rubber tires, wood wastes, and
combinations of fuels. Data collected dur-
ing the course of the two-year project will
include information on operational param-
eters such as mass balances of sludges and
fuels, air flow rates, temperature profiles
over time with changes in feed ratios, ash
characteristics, and scrubber water and gas
properties.
The grant is currently in the hardware
procurement and facilities modification
stage. Testing work will begin in the
spring of 1976. The grant work is being
cosponsored by the Wastewater Research Divi-
sion and the Solid and Hazardous Wastes
Research Division as part of its Wastes-as-
Fuels Research program.
Pilot Plant Pyrolysis
Pyrolysis is a process that holds much
potential as a disposal technique for or-
ganic materials. Pyrolysis, which is the
heating of a material in the absence of
air, reforms organic materials into lower
molecular weight compounds. The resultant
products can be in the form of a gas, a
liquid fraction, and a solid char, all with
appreciable fuel values. Theoretically,
air pollution is minimal, energy recovery
capacity is high, and costs are roughly
equivalent to those for incineration.
Pyrolysis had been proven effective on
many organic waste materials, including
municipal refuse (8). In order to explore
the application of the concept of pyrolysis
to sewage sludge disposal, EPA entered in-
to an interagency agreement with the U.S.
Bureau of Mines. Under the terms of this
agreement (EPA No. IAG-D4-0436) primary
sludge, activated sludge, sludge blends,
and mixtures of sewage sludge and solid
waste were pyrolyzed at the Bureau's
Pittsburgh Energy Research Center pilot
plant. A diagram of the pyrolysis pilot
plant is presented in Figure 5. Wastes are
fed into the batch retort and heated by an
electric furnace. Tars and gases are
cleaned and collected while the solid char
remains in the retort.
Table 5 summarizes the yields of char,
oil, and gas obtained from the pyrolysis of
dried activated sludge at 500° C and 900° C.
Pyrolysis of one ton of activated sludge at
900° produced approximately 1000 pounds of
char, 13000 cubic feet of gas, and 30 gal-
lons of oil. Total energy recovery was
over 12.5 million BTU's per ton of feed.
Demonstration of Oxygen-Enriched Pyrolysis
Budgetary constraints are such that
the funding of full-scale capital-intensive
demonstration projects would absorb all of
WRD's sludge disposal research funds.
Therefore, in order to obtain maximum usage
of the budgeted funds, attempts are made to
involve EPA in limited testing of existing
full-scale facilities. Such is the case
with a demonstration grant awarded to the
City of South Charleston, West Virginia.
Under the terms of this grant (EPA No.
559
-------
LEGEND
1. THERMOCOUPLE
2. ELECTRIC FURNACE
3. RETORT
4. TAR TRAP
5. TUBULAR CONDENSER
9.CARBON DIOXIDE SCRUBBER
10. CAUSTIC PUMP
11. LARGE WET-TEST METER
12. DRYING TUBE
13. LIGHT OIL CONDENSER
6. ELECTROSTATIC PRECIPITATOR 14. SMALL WET-TEST METER
7. AMMONIA SCRUBBER 15. GAS SAMPLE HOLDER
8. ACID PUMP
SAMPLE COCK FOR
j M H2S AND NH3 TESTS"
EXCESS GAS
IS FLARED
TO Btu AND
sp gr RECORDERS
J'^'A
Ti
^
;
ft
9
W//s
: 3
1
:fc^
a
* 1
5
;
r
WATER
OUT
WAT
N
5
ER
^ T 1
HEATING
ELEMENTS
ELECTRODES
WATER
OUT
NaOH NaOH
DRAINS
Figure 5. Pilot Plant Pyrolysis System.
TABLE 5. SUMMARY OF YIELDS FROM PYROLYSIS
OF DRIED ACTIVATED SLUDGE
Pyrolysis Temperature °C 500 900
Yields, Weight Percent of
Feed
Char ' 57.7 54.1
Gas 5.8 29.3
Tar, Oils, Aqueous 25.3 13.9
Yields, Per Ton of Feed
Char, Ib.
Gas, cu.ft.
Tar, Oils, Aqueous, gal.
Ammonium Sulfate, Ib.
Energy, Million BTU/Ton
of Feed
Char 5.1 4.6
Gas 1.9 5.4
Tar, Oils, Aqueous 4.0 2.6
1154 1082
2637 13415
57.7 29.6
103.3 73.4
S803769) dewatered sewage sludge will be
added to the feed to the 200 ton per day
solid waste oxygen refuse conversion plant
in that city. This plant, described
schematically in Figure 6, was constructed
to dispose of the municipal solid waste
generated in South Charleston (9). The
process was developed by the Union Carbide
Corporation and has the trade name Purox.
/o7
( TON
OXYG
T,
N f^\
\ ( TONS 1
S ^REFUSE'
EN ^
T 1.01
TONS
GAS
1 ••
1 -
GAS
CLEANING
TRAIN
1
0.22 TONS 0.03 TONS RECYCLE
0.7 TONS
"FUEL GAS
1
WASTEWATER
0.28 TONS
GLASS AND METAL
Figure 6. Inputs and products of Purox System.
560
-------
In the Purox system waste material is
fed into the top and oxygen into the bottom
of a shaft furnace. In the furnace there
is a combustion zone where the oxygen is
injected and a pyrolysis zone near the top.
In the combustion zone, the inorganic frac-
tion of the waste material is melted and
exits as a slag. In the pyrolytic zone
gases are produced from the organic frac-
tion of the feed. The fuel gas produced
has a heating value of about 300 BTU/SCF.
The grant work at South Charleston
will be of limited duration with testing
lasting only about four months. Through
the course of the testing, optimum ratios
of sludge to solid waste will be deter-
mined. The environmental impacts and eco-
nomic feasibility of codisposal in the
Purox system will be ascertained. Sludge
addition will begin in the spring of 1976
upon completion of a solid waste reliabil-
ity test.
PLANNED RESEARCH
Looking ahead to research that is gen-
erally planned for the next two years, we
see that program emphasis remains on re-
ducing cost and fuel consumption and on
neutralizing the environmental effects of
sludge combustion. Project mix will in-
clude feasibility, laboratory bench, and
full scale demonstration projects.
In the next year, which is our fiscal
year 1976, the most significant effort will
be an operational study of the modifica-
tions required to convert an existing
multiple hearth incinerator to pyrolytic
operation. The widespread utilization of
the multiple hearth furnace for sludge
combustion indicates that the conversion
approach may be the most direct method for
rapid implementation of sludge pyrolysis.
Also to be funded in 1976 will be a
laboratory study of the feasibility of
steam reformation of liquid sludge and raw
solid wastes in a rotary kiln reactor.
Under this concept, the water from the wet
sludge will serve as a steam medium for the
conversion of the solid organics to a gas
and an ash. The gas would then be cleaned,
burned, and the spent exhaust used to power
a turbine for electric power generation.
A third project in the next year will
be an in-house study to characterize the
char from sludge pyrolysis operations so
that applications for this by-product
might be found. A part of this study will
be an investigation of the use of the char
produced from pyrolysis of solid waste as
a conditioning agent and fuel for sludge
filtration and combustion.
Project planning for fiscal year 1977
can only be tentative. A mass and energy
balance may be performed around an existing
sludge incinerator so that the environ-
mental effects of conventional incineration
may be more completely described. The com-
bined incineration process determined to be
the most favorable through the ongoing
Weston study may be demonstrated. Further
studies of uses for carbon char from
pyrolysis will be conducted, with the main
emphasis being on the use of char as an
activated carbon with the recovery of
metals from the char as a by-product.
Finally, the costs of sludge pyrolysis will
be compared with the costs for conventional
sludge incineration.
CONCLUSIONS
While it is impossible to design and
fund a research program that encompasses
all worthwhile endeavors, it is believed
that the program described herein best
utilizes available funds and best reflects
foreseeable priorities. Future directions
in combustion research will be dependent on
any shifts in these priorities and on the
magnitude of program funding.
REFERENCES
1. Parrel1, J. B., "Overview of Sludge
Handling and Disposal," in Municipal
Sludge Management, Proceedings of the
National Conference on Municipal
Sludge Management, pp. 5-10, June 11,
1974.
2. Federal Water Pollution Control Act
Amendments of 1972, Oct. 1972.
3. Hathaway, S. W., and Olexsey, R. A.,
"Improving the Fuel Value of Sewage
Sludge," in News of Environmental
Research in Cincinnati, Nov. 1975.
4. Environmental Protection Agency Task
Force Report, "Sewage Sludge Incinera-
tion," Report No. EPA-R2-72-040
(Aug. 1972), NTIS PB 211323.
561
-------
5. Olexsey, R. A., "Thermal Degradation of
Sludges," in Pretreatment and
Ultimate Disposal of Wastewater
Solids, pp. 127-196, May 21, 1974,
Report No. EPA-902/9-74-002.
6. Smith, J. E., Jr., Hathaway, S. W.,
Farrell, J. B., and Dean, R. B.,
"Sludge Conditioning with Incinerator
Ash," Proceedings of the 27th Purdue
Industrial Waste Conference, Eng.Ser.
141, Part 2, 911-925 (May 2-4, 1972).
7. Hathaway, S. W., and Olexsey, R. A.,
"Improving Vacuum Filtration and
Incineration of Sewage Sludge by
Addition of Powdered Coal," presented
at 48th Annual Conference of the
Water Pollution Control Federation,
Oct. 9, 1975.
8. Sanner, W. S., Ortuglio, C., Walters,
J. G., and Wolfson, D. E., "Conver-
sion of Municipal and Industrial
Refuse into Useful Materials by
Pyrolysis," U. S. Bureau of Mines
Investigation 7428, Aug. 1970.
9. "Solid Waste Disposal Resource Recov-
ery," Union Carbide Bulletin F-3698.
562
-------
URBAN STORMWATER MANAGEMENT AND TECHNOLOGY IN THE UNITED STATES - AN OVERVIEW
R. Field
Storm and Combined Sewer Section, WRD, MERL
Edison, New Jersey 08817
ABSTRACT
Combined sewer overflows are major sources of water pollution problems, but even
discharges of stormwater alone can seriously affect water quality. Current approaches
involve control of overflows, treatment, and combinations of the two. Control may involve
maximizing treatment with existing facilities, control of infiltration and extraneous
inflows, surface sanitation and management, as well as flow regulation and storage. A
number of treatment methods have been evaluated including high rate screening and micro-
straining, ultra high rate filtration, dissolved air flotation, physical/chemical treat-
ment, and modified biological processes. A swirl flow regulator/solids separator of
annular shape construction with no moving parts has been highly developed. High rate
disinfection methods including new disinfectants have been applied. Promising approaches
involve integrated use of controls and treatment.
INTRODUCTION
Control and treatment of stormwater
discharges and combined sewage overflows
from urban areas are problems of increasing
importance in the field of water quality
management. Over the past decade much re-
search 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. A summary which includes problem
definition and management alternatives will
be presented.
PROBLEM DEFINITION
The background of sewer construction
lead to the present urban runoff problem.
Early drainage plans made no provisions
for storm flow pollutional impacts. Un-
treated overflows occur from storm events
giving rise to the storm flow pollution
problem.
Simply stated the problem is:
Iflhin a cMty £ak&> a. bath, what do you.
do uiith tii
-------
^| RAW
£52 COMBINED
| | STORM
BOD
SS
DO
5X107
B RAW
h%4 COMBINED
| | STORM
TOTAL COLIFORM
MPN/100 ml
TOTAL
NITROGEN
TOTAL
PHOSPHORUS
Figure 1. Representative Strengths of
Wastewaters (Flow Weighted
Means in mg/1)
100 times dry-weather flow. Even separate
storm wastewaters are significant sources
of pollution, "typically" characterized as
having solids concentrations equal to or
greater than those of untreated sanitary
wastewater, and BOD concentrations approxi-
mately equal to those of secondary efflu-
ent. Bacterial contamination of separate
storm wastewaters is typically 2 to 4
orders of magnitude less than that of
untreated sanitary wastewaters. Signifi-
cantly, however, it is 2 to 4 orders of
magnitude greater than concentrations
considered safe for water contact acti-
vities .
It is important to note that there is
no apt description of "typical" combined
sewage or stormwater runoff characteris-
tics due to the variable nature of the
rainfall-runoff patterns. Quality may
range from super-strong sanitary sewage
during the "first flush" to very diluted
sewage later in the storm. The composi-
tion is dependent on a number of factors,
including: length of antecedent dry
weather, local climatic conditions, con-
dition of the sewerage system and the
nature of the drainage area.
A few municipal studies can serve to
exemplify the problem. In Northampton,
England it was found that the total mass
of BOD emitted from combined sewer over-
flows over a two-year period was approxi-
mately equal to the mass of BOD emitted
from the secondary plant effluent. The
mass emission of suspended solids in com-
bined sewer overflow was three times that
of the secondary effluent.
The relatively poor flow characteris-
tics of combined sewers during dry-weather
when sanitary wastes alone are carried,
encourages settling and build-up of solids
in the lines until a surge of flow caused
by a rainstorm purges the system. Studies
in Buffalo, New York have shown that 20 to
30 percent of the annual collection of
domestic sewage solids are settled and
eventually discharged during storms. As a
result, a large residual sanitary pollution
load, over and above that normally carried
is discharged over a relatively short in-
terval of time, oftentimes resulting in
what is known as a "first flush" phenomenon.
This can produce shock loadings detrimental
to receiving water life. Aside from the
raw domestic and industrial sewage carried
in the overflow, non-sanitary urban runoff
in itself is a significant contributor to
the overflow pollution load. As the storm
runoff drains from urban land areas, it
picks up accumulated debris, animal
droppings, eroded soil, tire and vehicular
exhaust residue, air pollution fallout,
heavy metals, deicing compounds, pesticides
and PCB's, fertilizers and other chemical
additives, decayed vegetation, corrosion
products, hazardous material spills, to-
gether with many other known and unknown
pollutants.
A study on a 1.67 sq mi drainage area
in Durham, North Carolina has shown that
after providing secondary treatment of
municipal wastes, the largest single
source of pollution from the watershed is
separate urban runoff without the sanitary
564
-------
constituent. Additional treatment of
municipal waste could not be expected to
significantly affect the total per acre
yield of organic and suspended solids from
the basin on an annual basis, though it
might be necessary to protect the quality
of watercourses during periods of dry
weather and low stream flow.
When compared to the raw municipal
waste generated within the study area the
annual urban runoff of COD (as shown in
Figure 2.) was equal to 91 percent of the
raw sewage yield; the BOD yield was equal
to 67 percent, and the suspended solids
yield was 20 times that contained in the
raw municipal wastes.
2,000 -i
MUNICIPAL SEWAGE
URBAN RUNOFF
1,000 -
NO SEWAGE TREATMENT
91% TREATMENT OF
MUNICIPAL WASTE
Figure 2. Annual pollutant (COD) yield
from urban land runoff.
If Durham provided 100 percent 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 52 percent of the COD, 59 percent of
the ultimate BOD, and only 5 percent of
the suspended solids.
During storm flows, dissolved oxygen
content of the receiving watercourse was
found to be 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.
Besides the aforementioned conditions
in Durham, certain forms of solid waste
such as beer cans, broken glass bottles,
garbage, bed springs, shopping carts, etc.,
find their way into urban stream beds.
These solid wastes, believed to be typical
of urban streams, not only contribute to
lower water quality, but are aesthetic
pollutants adding to property devaluation
and are a hazard to public safety as well.
Figure 3. depicts coarse flotables from a
combined sewer overflow in the Chicago,
Illinois, USA area.
Figure 3. Coarse flotables from a combined
sewer overflow, Chicago, IL, USA
DESIGN CONSTRAINTS
Precise characterization of the
wastewater is virtually impossible because
of the variability in the character of
storm or combined wastewater and because of
the many physical difficulties in repre-
sentative sample collection. Also, because
of the intermittency and variability of
stormwater runoff and interrelated system
flows, there is no such thing as an
"average" design condition for storm flow
565
-------
treatment facilities. Therefore, a process
that performs only when conditions are
right or steady-state, may be too restric-
tive for practical applications.
CONTROL ALTERNATIVES
The concept of constructing new sani-
tary sewers to replace existing combined
sewers has largely been abandoned due to
enormous costs, limited abatement effec-
tiveness, inconvenience to the public and
extended time for implementation. It is
again emphasized that urban stormwater
runoff itself can be a significant source
of stream pollution. Sewer separation
would not cope with this pollution load.
It is further estimated that the use of
alternate measures could reduce costs to
about one-third of the cost of separation.
What Can Be Done About The Problem?
The viable control alternatives are
presented. First there is the problem at
the source, e.g., at the land and streets,
in the collection system, and off-line by
storage. We can remove pollutants by
treatment and by employing complex or in-
tegrated systems which combine various
combinations of control and treatment in-
cluding 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 cost-effective analysis involving
goals, values, and hydrologic-physical
system evaluations generally assisted by
mathematical model simulations, pilot-
scale trials, and new technology transfer.
Source Control
Source Control can be accomplished by
employing porous pavement and upstream
impoundment for flow attenuation; soil
erosion preventative measures; restrictions
on chemicals used for deicing, fertiliza-
tion, pest control, and leaded gasoline;
zoning and land use regulations; and im-
proved neighborhood sanitation practices.
The theory behind source controls is to
limit the supply of contaminants. The
benefits are not only reduced water pollu-
tion but also cleaner and healthier en-
vironments .
It is recommended that the newer and
more promising street cleaning equipment
such as vacuum sweepers, air brooms and
wet scrubbers be further evaluated and
employed as opposed to conventional sweep-
ing and flushing methods. The newer devices
offer benefits in picking up the urban run-
off pollution causing dust and dirt parti-
cles rather than redistributing them for
aesthetic purposes as the conventional de-
vices do.
Sewerage System Control
In sewerage or collection system con-
trol the emphasis is on optimizing the
existing collection system. Measures which
can be used include:
-Dry-weather flushing to reduce dry-
weather solids accumulation and
thereby relieving the overflow first
flush.
-Polymer feed to reduce overflows by
increasing pipe carrying capacity.
-Infiltration/Inflow prevention and
correction.
-And improved flow regulators or di-
version devices, e.g., the swirl,
helical and fluidic types.
A swirl flow regulator/solids-liquid
separator being demonstrated in Syracuse,
NY, USA is shown on Figure 4.
Figure 4. Swirl Regulator—Flotables en-
trapment during wet-weather
operation, W. Newell St.,
Syracuse, NY, USA
566
-------
Figure 5. is a schematic diagram. The de-
vice, of simple annular shape construction,
requires no moving parts. It provides a
LEGEND
InUt Romp
Flow D.fl.ttor
S.um Ring
Overflow Woir and W.ir Plot.
Spoilm
Flooiabl.I Trop
Fowl Sow.r OulUt
Floor Gutl.ri
Figure 5. Isometric View of Swirl Regula-
tor/Concentrator .
dual function, regulating flow by a cen-
tral circular weir while simultaneously
treating combined wastewater by a "swirl"
action which imparts liquid-solids separa-
tion. The low-flow concentrate is di-
verted 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 developmental model in operation is
shown in Figure 6. The device is capable
of functioning efficiently over a wide
range of 80:1 of combined sewer overflow
rates, and can effectively separate sus-
pended matter at a small fraction of the
detention time required for conventional
sedimentation or flotation (seconds to
minutes as opposed to hours by conven-
tional tanks). The capital cost of the
6.8 mgd Syracuse prototype was $55.000.
O&M is estimated at $2,000/yr. Swirl
construction cost curves are presented
in Figure 7.
Figure 6. Overhead view of swirl regulator/
separator in operation, Labora-
tory Hydraulic Model, LaSalle,
Quebec, Canada
3 «
o (DRAFT} EPA CONTRACT NO. 66-03-0371
• SWIRL PROTOTYPE, WEST NEWELL ST.
SYRACUSE. NEW YORK, U.S.A.
IAS BUILT WITHOUT PUMPING)
° SWIRl PROTOTYPE, WEST NEWELL ST
SYRACUSE, NEW YORK, USA
{PROJECTED FOR 1007. GRIT REMOVAL
BASED ON REFERENCE 9)
1007. ORIT REMOVAL
90% GRIT REMOVAL
as 2
324
169 8
645
25S.O
969
339.6 DESIGN FLOW RATE, cu m/min
129.0 DESIGN FLOW RATE, mgd
Figure 7.
Estimated construction cost
curves—swirl regulator/separa-
tor
Preliminary tests indicate at least 50 per-
cent removal of suspended solids and BOD.
Tables 1. and 2. contain further details
on the Syracuse prototype treatability.
Figures 8. and 9. containing influent and
effluent pollutographs show total sus-
pended solids and BOD removed during a
storm.
The swirl concept is also being
piloted in Denver, Colorado and Toronto,
Canada. At Denver it is being used as a
degritter and at Toronto as a primary
clarifier. This work is still ongoing,
however preliminary test results are very
encouraging. A helical or spiral-type
regulator/separator has also been developed
based on principles similar to those of
the swirl device. This device is benefi-
567
-------
Table 1. Suspended Solids Removal
Swirl Concentrator
Mass Loading
kg
Storm No.
02-1974
03-1974
07-1974
10-1974
14-1974
01-1975
02-1975
06-1975
12-1975
14-1975
15-1975
a
For the
Inf.
374
69
93
256
99
103
463
112
250
83
117
Kff
179
34
61
134
57
24
167
62
168
48
21
conventional
SS concentration
inflow.
7
Rem.
52
51
34
48
42
77
64
45
33
42
82
regulator
Conventional Regulator
Average SS
per storm, mg/1
Inf.
535
182
110
230
159
374
342
342
291
121
115
removal
of the foul underflow
Eff.
345
141
90
164
123
167
202
259
232
81
55
%
Rem.
36
23
18
29
23
55
41
24
20
33
52
calculation,
equals
the SS
Inf
374
69
93
256
99
103
463
112
250
83
117
it is
Mass Loading
kg
Underflow
101
33
20
49
26
66
170
31
48
14
72
assumed that the
%
Rem.a
27
48
22
19
26
64
34
27
19
17
61
concentration of the
Data reflecting negative SS removals at tail end of storms not included.
"e c
J 0-
< *?
Table 2. BOD REMOVAL li
0.076 -
0.152 -
0.229 -
0.305 -
U[ 1 1 I 1 1 M 1 I 1 1 1 1
1
STORM #1 3/24/75
5 DAY BOD
0 MASS LOADING (INFLU
Average BOD
Mass Loading, kg per storm, mg/1
Storm % %
No. Inf. Eff. Rem. Inf. Eff. Rem.
7-1974
1-1975
2-1975
266
97
175
48
30
86
82
69
51
314
165
99
65
112
70
79
32
29
« MASS LOADING (EFFLUENTI
FLOW
o MASS LOADING (INFLUENT)
A MASS LOADING (EFFLUENT)
7 00 8:00 9 00 10.00 11.00 12:00 13:00 14:00 15:00 16:00 17:00
TIME, hrs
Figure 8. Swirl regulator suspended solids
removal, W.Newell St., Syracuse,
NY, USA
11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00
TIME, hrs
Figure 9. Swirl regulator BOD,- removals,
W. Newell St., Syracuse, NY, USA
cial as its solids separation action is
created by only a bend in the sewer line.
Other collection system control
methods are:
-In-sewer or in-line storage and
routing whereby the intent is to
assist a dispatcher in routing and
storing storm flows to make maximum
use of existing interceptors and
sewer line capacity. The general
approach comprises remote monitoring
of rainfall, flow levels, and some-
568
-------
times quality, at selected locations
in the network, together with a
centrally computerized console for
positive regulation.
-And lastly, the most common approach
is off-line or external storage with
concrete tanks used most often. The
concept is to capture wet-weather
flow and bleed it back to the treat-
ment plant during low flow dry-
weather periods. The results of
controlling overflow by detention
are shown on Figure 10. Notice how
an entire hypothetical overflow
event at point A is prevented by
storage with controlled dewatering.
RAINFALL
T
T
T
RAINFALL
-OVERFLOW
s- CAPACITY
--*-- OF
PLANT
»• t
RAINFALL
•*"| RAINF
r\
t TIMED
HYDROGRAPH AT "A"
WITHOUT CONTROL
CONTROLLED
HYDROGRAPH AT
"A"
Figure 10. Results of controlling storm
flow by storage
Storage facilities possess many of
the favorable attributes desired in storm
flow control: they are capable of pro-
viding flow equalization; are simple to de-
sign structurally, and operate; respond
without difficulty to intermittent and
random storm behavior; are relatively un-
affected by flow and quality changes; and
frequently can be operated in concert with
regional dry-weather treatment facilities.
Disadvantages of storage facilities in-
clude their large size, high cost, and
dependency on other treatment facilities
for dewatering and solids disposal. A
3.5 MG asphalt lined storage basin in
Chippewa Falls, WI, USA eliminated 59 out
of 62 river overflows during the evalua-
tion period.
Treatment
The various treatment methods used
for storm flow include physical and
physical-chemical, biological, and disin-
fection. 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 and/or chemical treatment
processes in many ways are well suited to
storm flow applications, particularly with
respect to solids removal because of their
resistance to shockloads and rapid startup
and shutdown characteristics. These pro-
cesses include sedimentation, dissolved
air flotation, screening, filtration,
carbon adsorption and special swirl separa-
tion.
To reduce capital investments, demon-
stration projects have been directed
towards operations approaching the maximum
loading boundaries. Applications include
their use for pretreatment or roughing,
for the main or sole treatment, and,
particularly in the case of microstrainers
and filters, as effluent polishing devices.
The microstrainer is conventionally
designed for polishing secondary sewage
plant effluent at an optimum rate of
approximately 10 gpm/sq ft. Tests on a
pilot microscreening unit of 23 micron
aperture in Philadelphia have shown that at
high influx rates of 25-30 gpm/sq ft, sus-
pended solids removals in combined over-
flows as high as 90% can be achieved.
Since overflows are not continuous as
sanitary flows are occurring about five
percent of the total time, a sacrifice of
screen life for increased hydraulic treat-
ment rate is worthwhile.
A study in Cleveland showed high
potential for treating combined sewer over-
flows by in-pipe filtration using anthra-
filt and sand in a 7 to 8 foot bed.
Figure 11. depicts the Cleveland pilot
plant. With the high loadings of 16 to 32
gpm/sq ft surface area, removal of solids
was effectively accomplished throughout
the entire depth of filter column. Test
work showed suspended solids removal up to
569
-------
Figure 11. Pilot plant, Cleveland, OH,
USA
and exceeding 90 percent and BOD removals
in the range of 60 to 80 percent. Substan-
tial reductions, in the order of 30 to 80
percent of phosphates, can also be ob-
tained.
Results from a 5.0 mgd screening and
dissolved-air flotation demonstration pilot
plant in Milwaukee, WI, USA indicate that
greater than 70 percent removals of BOD
and suspended solids are possible. Find-
ings also revealed 85 to 97 percent re-
duction in phosphate can be achieved as an
additional benefit, by employing chemical
coagulants.
Biological treatment of storm waste-
waters must overcome some serious draw-
backs: (1) the biomass used to assimilate
the waste constituents must either be kept
alive during times of dry weather; and
(2) once developed, the biomass is highly
susceptible to washout by hydraulic surges
or overload.
Examples of biological treatment
applications to stormwater include (1) the
contact stabilization modification of
activated sludge, (2) high rate trickling
filtration, (3) bioadsorption using
rotating biological contactors, and (4)
oxidation lagoons of various types. The
first three are operated conjunctively
with dry-weather flow plants to supply the
biomass and the fourth involves long term
storage of the flows. With the exception
of lagoons, some form of pre-unit flow
equalization and control is essential for
biological processes.
The most commonly used disinfectants
under the research program are sodium
hypochlorite, chlorine dioxide, and ozone.
Because the disinfectant and contact de-
mands are great in storm flow applica-
tions, due to intense flowrates, current
research centers on high-rate applications
(1) by imparting turbulence, (2) use of
alternative, more rapid disinfectants, and
(3) on-site generation of disinfectants.
Successful results in all these areas have
been demonstrated.
Integrated Systems
By far the most promising approach to
urban stormwater management is the inte-
grated use of control and treatment with
an areawide multidisciplinary perspective.
When a single method is not likely to
produce the best possible answers to a
given pollution situation, various treat-
ment and control measures—as previously
described—may be combined for maximum
flexibility and efficiency. One such com-
bination might be: in-sewer or off-system
storage for subsequent overflow treatment
in specifically designed facilities,
followed by groundwater recharge or re-
covery for water sports and aesthetic
purposes. Another combination might be
flow retention with pump or gravity bleed-
back to the sanitary sewerage system.
In all cases the optimum abatement
plan for stormwater overflow pollution
will have to be evaluated separately for
the geographical area in consideration.
Aside from climatological conditions,
terrain, and land uses, choice of control
and treatment will depend on the existing
sewerage system configuration. For
example, separate systems with large
contributory areas and few overflow points
present problems and require design
philosophies which differ from those of
systems divided into many subdrainage
areas with individual combined wastewater
outfalls.
The temporary storage concept, pre-
viously discussed as a control process,
also provides for a certain degree of
treatment by settling, for excessive
570
-------
overflows greater than the design storage
capacity discharging directly to the re-
ceiving stream. Likewise, this settling
potential for flows less than design capa-
city, together with on-site solids disposal
and/or controlled dewatering to the receiv-
ing stream (in accordance with assimilation
capacity), which are usually overlooked,
should be definitely considered.
Another approach in overcoming the
extreme variation in overflow rates is to
provide surge facilities prior to the
storm flow treatment plant or the munici-
pal plant. The surge basin(s) (or exist-
ing combined sewers) could furthermore
serve a dual function in equalizing not
only wet-weather flows but dry-weather
flows as well. In this way, a single
future treatment system can readily be
designed for storm and sanitary flow
conditions. This could also assist pre-
sently overloaded sanitary plants in
obtaining more uniform operation. Short-
term storage incorporated into the treat-
ment plant would even out the daily cycle
of dry-weather flows allowing for more
efficient use of the treatment process
over the entire 24 hours. Equalization
would permit reduced treatment process
design capacity. Further analysis is
necessary to determine the most economical
break-even point between the amount of
storage versus the treatment capacity.
The designer should recognize the wet-
weather treatment plant's capability to
draft stored flow continuously while it is
raining in his evaluation of the optimum
surge-treatment system. Dual-use wet-
weather storage and treatment facilities
built in conjunction with dry-weather
plants can be used to improve dry-weather
treatment capacity and effectiveness
the vast majority of the time when it is
not raining.
The program has fostered various
schemes which reclaim storm flows for
beneficial purposes including the enhance-
ment of visual aesthetics, recreation, and
water supply.
Mount Clemens, MI, USA has installed
a treatment-park system involving dis-
charge of combined sewage overflows into
a series of three "lakelets" each equipped
with surface aerators (schematic, Fig-
ure 12.). Effluents pass from one pond to
the next through microstrainers and
filters, and the final effluent is chlo-
COMBINED SEWER
COMBINED SEWER
64 MGD
LAKELET NO. 1
• SETTLING (FOUR DAYS-MAXIMUM STORM)
• MECHANICAL & NATURAL SURFACE AERATION
• AEROBIC S ANAEROBIC DIGESTION
• SCUM REMOVAL
I I
-
I MGD
MICROSTRAINER
• MECHANICAL FILTRATION
• SUSPENDED SOLIDS S BOD REMOVAL
• ALGAE (PHOSPHOROUS-NITROGEN) REMOVAL
(6) 1 MGD
CHLORINE-CHLORINE DIOXIDE
• DISINFECTION £ ODOR CONTROL
1 MGD
LAKELET NO. 2 ©
• NATURAL SURFACE AERATION
• PHOTOSYNTHETIC OXYGENATION
I MGD
LAKELET NO. 3
• MECHANICAL & NATURAL SURFACE AERATION
• PHOTOSYNTHETIC OXYGENATION
I MGD
PRESSURE FILTER
• HIGH RATE SAND FILTRATION
• SUSPENDED SOLIDS S BOD REMOVAL
• ALGAE (PHOSPHOROUS-NITROGEN) REMOVAL
©
CLINTON
RIVER ©
Figure 12.
©
Schematic diagram of Mount
Clemens, MI, USA facility.
rinated. This control and treatment
scheme is designed to have no adverse
aesthetic impacts and blend into a sur-
rounding park development and the waters
are being reclaimed for recreation and
reused for park irrigation.
Computer Assistance
Mathematical models are needed to
predict complex dynamic system responses
to variable and stochastic climatological
phenomena.
These models have been developed and
applied at many levels of sophistication
including EPA's Storm Water Management
Model (SWMM) which is capable of represent-
ing the gamut of urban runoff conditions
both qualitatively and quantitatively from
the uppermost catchment point to the down-
stream receiving water.
571
-------
RESULTS AND COSTS
Detroit found the cost of in-system
controlled storage to be as low as $0.02
to $0.04/gal. This range was approximately
one-tenth the estimated cost for large
•off-line facilities.
Typical abatement system construction
costs are summarized based on mid-1973
prices.
Table 3. TYPICAL COSTS OF
COMPONENT DEVICES AND OPERATIONS, ENR 2000
TOTAL STORAGE
1.56 mo x S 0.50/oal
= $ 760,000
In-line storage
Off-line storage
*Physical treatment
*Physical/chemical
treatment
$0.02-0.25/gal
$0.20-A.75/gal
$5,000-35,000/mgd
$35,000-80,000/mgd
^Biological treatment $60,000-80,000/mgd
*for a hypothetical 25 mgd plant
These data are based on a very limited
number of specific projects; thus, they
represent only an order of magnitude
placement. In extrapolating these costs
into master plan systems, such as the City
of San Francisco's (CA, USA), the totals
frequently approach $500-1,000/acre. It
is estimated that the national average per
acre cost for sewer separation would be
$20,000-$30,000 today. Whereas a similar
estimate for the control alternatives
would fall in the neighborhood of
$10,000/acre.
A simplified example will serve to
illustrate an advantage of integrated
approaches. Assume a design composite
storm overflow for a combined catchment
area is three hours long and the hydro-
graph (Figure 13.a.) is triangular shaped
with a maximum value of 25 mgd occurring
at the end of the first hour. Total
containment in storage would therefore
require a capacity of 1.56 MG which at a
unit cost of $0.50/gal would cost $780,000
to construct. Similarly a treatment
facility designed for the maximum flowrate
might cost $750,000 at $30,000/mgd. A
10 mgd plant, however, coupled with a
storage capability of 0.56 MG would accom-
plish the same objectives for $580,000 as
illustrated by Figure 13.b. Of particular
importance is the opportunity for the
treatment plant to operate at its design
capacity for a sustained period of time.
TOTAL TREATMENT
25 MGD x $ 30,000/MOD
= S 750,000
Figure 13. M Soparolo Approach
Storage or Treatment
NET STORAGE
0.56 mg X $ O.SO/gn
TREATMENT
10 MGD x $ 30,000/MGD = $ 300,000
TOTAL $ 580,000
= $ 280,000
]_3 . (b) Integrated Approach
Storage and Treatment
While prototype installations in
operation today are still relatively few
in number, some impressive results have
been obtained. The in-system storage
concepts have proven feasible to operate
and maintain with a major curtailment of
overflow occurrences and durations. Off-
line storage and detention-chlorination
facilities are proven performers with
additional benefits for backing up over-
loaded treatment works innovated. Storm
flow facilities constructed in parallel
with conventional dry-weather flow treat-
ment plants have introduced dual-use
functions improving even dry-weather
performance as well as increasing treat-
ment capacities during storm periods.
CONCLUSIONS
All facts point to a real requirement
for treating and controlling stormwater
runoff and combined sewer overflows. In
view of the tremendous quantities of
pollutants bypassed during rainfall from
the combined sewer system, it does not
seem reasonable to debate whether secondary
treatment plants should be designed for
80, 85 or 90% BOD or suspended solids re-
moval, when in fact the small increments
gained in this range are completely over-
572
-------
shadowed by the bypassing occurring at
regulators during wet-weather flow. During
a single storm event, from 95% to 99% of
the total organic load is attributed to
runoff generated discharges. On an annual
basis the storm associated organic load
may be from 40% to 80% the total figure.
It has been estimated that detrimental
wet-weather receiving stream impacts can
last for days.
It is a distinct possibility that
communities may make expensive sewage
treatment plant improvements and still
not achieve water quality goals due to
the impact of urban runoff (or some other
nonpoint source) unless steps are taken
to harmonize land use with water quality
or treat the runoff waters to reduce their
adverse effects on receiving streams.
Along with planning to upgrade
secondary sewage treatment plants, and
because of possible contravention of stream
standards, we should carefully assess the
potential impact of urban runoff.
The multi-billion dollar treatment
plant upgrading and expansion program now
going on throughout the country will do
much to alleviate pollution of our waters.
However, means of mitigating the effects
of combined sewers and stormwater must
also be found if we hope to abate the
pollution in an optimal manner. Wet-
weather standards continue to be promul-
gated.
573
-------
ACTIVATED CARBON FOR MUNICIPAL WASTEWATER TREATMENT
James J. Westrick
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
ABSTRACT
Full scale use of activated carbon adsorption as a municipal wastewater treatment
process has resulted in part from the early vigorous research efforts of EPA's predecessor
organizations. Research is continuing in pilot plant operations in Cincinnati and
elsewhere to further understand the process and its implications in the water pollution
control effort. Completed and ongoing research projects dealing with influence of
chemical pretreatment, pH, nitrate addition, and breakpoint chlorination are discussed.
The removal of general organic pollutants, heavy metals and specific organics such as
halomethanes, is described with regard to the studies conducted or sponsored by EPA. A
brief description of the independent physical-chemical system at Rocky River, Ohio, and
the performance and cost evaluation study of the completed facility are included.
INTRODUCTION
The use of activated carbon for
municipal wastewater treatment was one of
the principal results of the research
sponsored in the early days of the Advanced
Waste Treatment group of the U.S. Public
Health Service. Research at Harvard,
Pittsburgh, Cincinnati, Lebanon, Pomona and
Tahoe established the feasibility of
utilizing granular activated carbon beds
for the removal of organic matter from
secondary effluents and regenerating spent
carbon for reuse. The first full-scale
application of this research was the 7.5
mgd (28,000 cu m/day) advanced waste
treatment facility at South Tahoe, Cali-
fornia. Here activated carbon was utilized
as the last treatment step in an extensive
train of processes beginning with
conventional activated sludge through two-
stage lime clarification, ammonia stripping,
filtration and finally, adsorption. Lime
sludge recalcination and carbon regeneration
were also incorporated. This pioneering
facility has been on stream since 1968,
producing high quality water for irrigation
and recreational uses.
Encouraged by the success at Tahoe
and assisted by Research Development and
Demonstration Grant funding, several other
local authorities constructed tertiary
carbon systems at Colorado Springs,
Colorado, Nassau County, New York, and
Piscataway, Maryland.
A number of studies by private
interests and research sponsored by EPA's
predecessor organizations opened the
possibility of using carbon as an alter-
native to biological systems for secondary
treatment. Activated carbon was shown to
be effective for the production of high
quality effluent when preceded by efficient
chemical clarification. A flurry of
feasibility studies followed and several
municipalities opted for systems consisting
of chemical clarification of raw wastewater
followed by activated carbon beds. Such
systems, called Physical-Chemical (P-C)
Systems, promised some apparent advantages
when compared to conventional secondary
treatment systems. These are shown in
Table 1. The space savings resulted in
the selection of P-C treatment at Rocky
River and Cleveland Westerly. It is
especially dramatic at Cleveland, where a
574
-------
50 mgd (190,000 cu m/day) P-C system will
be constructed on a 7-acre (3 ha) site,
with room for future expansion. Other
municipalities chose P-C to best cope with
local conditions, such as unusual raw
wastewater characteristics or high quality
effluent requirements.
TABLE 1 - FEATURES OF P-C TREATMENT
1. Minimum land requirements
2. Low sensitivity
3. Unaffected by toxic materials
4. Flexibility of design and operation
5. High organic removal
6. High phosphorus removal
7. Capability for heavy metal removed
Because of the relatively high
purchase price of granular activated carbon,
regeneration and reuse of spent carbon is
commonly practiced. All municipal
regeneration systems currently in use or
planned utilize thermal regeneration
systems wherein spent carbon is raised to a
temperature of ~900°C-1000°C by contact
with hot gases of combustion in a multiple
hearth furnace. Steam is normally injected
to oxidize the adsorbed organics.
Whether on-site regeneration is
economic depends upon carbon utilization
rate, the plant size, the delivered cost of
virgin carbon, local labor cost, and
installed cost of regeneration equipment.
On-site regeneration in multiple hearth
furnaces is not feasible at very small
plants, because the smallest fully
automated commercially available multiple
hearth regeneration furnace has a firm
capacity of 3000 Ib/day (1400 kg/day).
Other types of thermal regeneration systems
may be developed in the future which will
allow economic regeneration of spent carbon
at small facilities. One example is a unit
which uses infrared lamps to heat carbon
passing through a controlled atmosphere on
a continuous conveyor. Rotary kilns might
also be economic at the small plant size.
The demonstrated success of granular
carbon regeneration both at Tahoe and in
the sugar industry and uncertainty as to
the feasibility of regenerating powdered
carbon (mean particle size ~ 10-20 y)
favored the development of granular carbon
over powdered carbon systems for municipal
wastewater applications. Powdered carbon
was shown to be effective both in tertiary
and P-C applications in a series of pilot
studies sponsored by EPA and predecessor
organizations. Pilot scale regeneration
has been successful at several locations,
and in fact, a 10 T/day (9000 kg/day)
powdered carbon regeneration system is
now operated by a carbon manufacturer to
regenerate spent sugar carbon. Thus,
renewed interest in powdered carbon for
municipal use is expected.
CINCINNATI PILOT PLANT ACTIVITIES
Several recent projects have been
conducted at the Cincinnati EPA facility
to learn more about the use of activated
carbon for municipal wastewater treatment.
Effects of Chemical Pretreatment on Carbon
Adsorption (1)
As suggested earlier, when carbon is
used in the P-C system (no biological
treatment), it is normally preceded by
chemical clarification and sometimes
filtration. The chemicals used are those
which also precipitate phosphorus, namely
lime or salts of aluminum or iron. The
chemical clarification systems have
generally been selected on the assumption
that the type of chemical pretreatment
used would have no effect upon the sub-
sequent adsorption of organics by activated
carbon. However; several reports were
published which claimed that high pH lime
clarification caused alkaline hydrolysis of
high molecular weight organic molecules and
produced a subsequent beneficial effect on
carbon adsorption in terms of effluent
quality and carbon capacity. In order to
investigate the influence of chemical
pretreatment on carbon performance, three
P-C pilot systems were constructed, operated
with three distinctly different chemical
clarification schemes. Data were collected
and evaluated with special emphasis given
to carbon performance.
The three chemical treatments used were
1. High lime 690 mg Ca(OH)2/l,pH>ll.5
neutralized to pH<7 by C02+H2S04
2. Low lime - 320 mg Ca(OH)2/l+15 mg
Fe3+/l, pH ~ 10
3. Iron
62 mg Fe3+/l, pH 6.0-6.5
575
-------
A schematic of the iron system is shown in
Figure 1. The lime systems were similar
with the addition of retention and
neutralization tanks.
Each chemical clarifier was followed
by a dual-media (anthracite-sand) filter
and a carbon adsorber. Each adsorber was
made up of 5 - 4-in-(10 cm) diameter tubes
in series with a total depth of 18 ft
(5.5 m) of Filtrasorb 300 granular carbon.
The application rate was 4 gpm/sq ft
(10 m/hr) for a total empty bed contact
time of 34 min. The systems were operated
continuously for eleven months except for
brief shutdowns for minor mechanical
failures.
The overall performance of the three
systems is presented in Table 2. The
source of raw sewage for this project was
a 30-in-(76 cm) diameter interceptor sewer
serving a residential-commercial neighbor-
hood. The sewage could be described as
weak, partly because of infiltration
during periods of rainfall. There were
some differences in performance of the
three systems based on the removal of the
Raw Sewage
Ferric Sulfate
To Waste
s)Denotes sample point
Figure 1. Flow diagram, iron system.
Table 2. Average performance of P-C Pilot System.
Item
Raw Sewage
Low-Lime System:
Clarifier Eff.
Filter Eff.
Carbon Eff.
Iron System:
Clarifier Eff.
Filter Eff.
Carbon Eff.
High-Lime System:
Clarifier Eff.
Filter Eff.
Carbon Eff.
TOC
'"8/1
59.9
17.4
12.5*
7.1*
14.1
9 . 5*
4.9*
15.9
12.9*
6.2*
% Re-
moval
71
79
88
76
84
92
73
78
90
COD
rag 1 1
215
52.0
36.9*
22.8*
42.2
27.8
17.0*
43.0
36.5*
20 . 8*
% Re-
moval
76
83
89
80
87
92
80
83
90
TSS
mg/1
98
20
7
6
28
12
7
17
9
8
% Re-
moval
80
93
94
71
88
93
83
91
92
P
mg/1
9.2
1.3
0.9
0.9
1 .0
0.3
0.3
0.5
0.5
0.5
7. Re-
moval
86
90
90
89
97
97
95
95
95
Alk.
(mg/1 as
CaC03)
209
165
156
165
54
62
66
209
200
163
Turb.
(JTU)
38
11
5
11
21
13
12
8
4
7
Iron
(mg/1)
0.7
1.3
0.4
0.7
8.2
3.5
2.9
Color
Units
16
7
10
5
14
5
Ca
mg/1 as
CaC03)
182
200
190
204
410
385
389
MS
(mg/1 as
CaC03)
65
46
43
32
7
9
8
rlow-wei gh t ed avcrag es.
11 other values are arithmetic, means.
576
-------
major pollution parameters. The iron
system generally produced the lowest
residuals in terms of organics and
phosphorus while the residual suspended
solids in the effluents were essentially
equal. The carbon systems were run to
exhaustion; thus the organic concentrations
in the effluents are the averages of values
ranging from very low concentrations with
fresh carbon to essentially complete
breakthrough.
Figure 2 illustrates the decline in
performance of the carbon systems with
cumulative applied loading. It is apparent
that the removal of TOC by the iron-carbon
adsorber declined at a greater rate than
the lime systems. This is to be expected
since the iron clarified-filtered waste-
water had a lower concentration of TOC
than the other streams. According to
accepted adsorption models, organic removal
capacity of carbon decreases as the
concentration of organics in the wastewater
decreases. The high lime system performed
somewhat better than the low lime system.
100-
12-
80-
o
E
£40-
20-
HIGH LIME
IRON
LOW LIME
0 5 10 15
Cumulative Applied TOC, A,
20 25 30 35
g TOC Applied
100 g Carbon
Figure 2. Performance of activated carbon systems.
O>
E
O
O
8-
SYSTEM
FEED TOC
IRON 9.5mg/l
LOW LIME 12.5mg/l
HIGH LIME 12.9mg/l
Single Stage Carbon Dosage, Ds, mg/l
200 100 75 50 40 30
I
I
75
I
I
5 10 15 20 25 30 35
Specific Throughput, q, l/gm
Figure 3. Idealized breakthrough curve.
If, at a given specific throughput, the
carbon in a single adsorber is considered
exhausted, it would be removed and replaced,
and the carbon dosage at that point would
be calculated as the reciprocal of the
throughput in appropriate units. Figure 3
shows that for any given effluent standard
the iron system will be able to treat more
sewage and the carbon dosage will be less
than for the other systems.
A single carbon contactor treating an
entire waste stream is the least efficient
contacting system from a standpoint of
carbon loading. The entire contents of the
single-stage contactor must be removed and
replaced with virgin or regenerated carbon
when the effluent reaches the specified
limit. Only a fraction of the carbon in
the bed is completely saturated while a
large portion of the bed is in a state of
partial exhaustion. Other methods of
contacting are commonly used, such as
multiple-staged series operation, pulsed
bed operation and multiple single-stage
parallel operation. Of these, only the
multiple single-stage parallel system can
be applied directly to the data obtained in
this project, since these adsorbers were
strictly single stage.
In Figure 3 the breakthrough of TOC
is shown as a function of specific
throughput or liters of sewage passed
through the adsorber per gram of carbon in
the adsorber. Also shown on the abscissa
is the single-stage carbon dosage cor-
responding to the specific throughput.
The carbon utilization in single-stage
contacting can be improved by dividing the
total contactor volume requirement into a
number of parallel contactors. By starting
the contactors in staggered sequence, it
is possible to have on-stream at any given
time contactors in various stages of ex-
haustion. Thus, effluents from more
heavily loaded contactors can be blended
577
-------
1.0-
c
o
•*-
o
(0
0
ro
0)
III i-
o) 2
0) O
ro ro
§ «
JD O)
ro .E
O W
0.5--
—r
5
—r—
10
—I—
15
—i—
20
Number of Parallel Single Stage Contactors
Figure 4. Effect of multiple contractors on carbon dosage.
with effluents from less heavily loaded
contactors to produce the desired effluent
quality.
Figure 4 shows the savings in carbon
as the number of parallel contactors
increases. For example, the carbon dosage
for an eight-contactor system with stag-
gered start-up is 56% of the single
contactor dosage.
To provide additional information for
the performance comparison, cost estimates
for treatment by carbon systems that
perform in accordance with the data ob-
tained in this study were made. These
estimates include amortization of capital
as well as operation and maintenance costs.
The assumptions used in the estimate are
shown in Table 3. The estimates were made
for a 10 mgd (38,000 cu m/day) carbon
adsorption system with eight parallel,
single-stage contactors at 34 min contact
time. The relationship of carbon treatment
cost to carbon dosage was computed and is
shown in Figure 5. The treatment cost
increases with carbon dosage; nearly all
of the increased cost results from
regeneration operation and maintenance
cost, including carbon makeup.
5-
~ 3-
a
O
20
15
10
O
O
c
0)
E
a
O
20 40 60 80 100 120
Carbon Dosage, mg/l
140 160
Figure 5. Relationship of carbon treatment cost
to carbon dosage.
Figure 6 shows the effect of the
three pretreatment systems on the cost of
carbon treatment for varying effluent TOC
levels. Differences in carbon treatment
cost for the three systems studied are
significant at the low effluent TOC levels,
but they diminish as the required level of
treatment is reduced. Over the entire
range of effluent TOC considered in this
578
-------
Table 3 Input Assumptions for
Carbon System Cost Estimation
Item
Input Assumptions
Avg. daily flow
Peak flow
Amortization
interest rate
Amortization
period
STP CCI (EPA)*
Wholesale price
index*
Hydraulic surface
loading
Carbon contact
time
No. of contactors
Carbon cost
Regeneration loss
Power cost
Fuel cost
Labor wage rate
10 mgd(38,000 cu m/day)
14.8 mgd (56,000 cu
m/day)
6.0%
25 yr
2.025
1.535
4 gpm/sq ft(10 m/hr)
34 min
8
$0.42/lb ($0.93/kg)
8%
$0.020/kw hr
$0.10/therm($0.0006/MJ)
$5.50/hr
"June, 1974.
study, the lowest feed TOC provided by the
iron pretreatment system permits the least
cost carbon treatment. High-lime pre-
treatment results in lower cost carbon
treatment than low-lime pretreatment with
the advantage diminishing greatly at
higher allowable effluent TOC levels.
These carbon treatment cost compari-
sons can thus be incorporated into total
system cost comparisons to provide a
decision making mechanism for selecting the
least total cost system. Such additional
parameters as clarification area require-
ments, sludge dewatering requirements,
neutralization requirements, complexity of
operation and maintenance, influent quality
characteristics, and effluent quality
requirements should all be taken into
account in selecting the chemical pre-
treatment system. Figure 6 suggests that
differences in carbon treatment cost that
would result from utilizing the various
chemical pretreatments studied here are
large enough at low effluent TOC levels to
be considered in making the selection of
chemicals. For example, if the effluent
TOC requirement were 5 mg/1, the low-lime
pretreatment system, including clarifica-
tion, neutralization, filtration, and
sludge handling, would have to cost at
least 3.4
-------
Removal of Heavy Metals by P-C Processes
Phase 1 (2)
Concurrent with the previously
described study, heavy metals were added
to the influent of each pilot plant.
Samples of spiked raw sewage, clarifier
effluent, filter effluent, carbon effluent,
sludge and filter backwash were analyzed
for the specified metal. The analytical
determinations were verified by mass
balance procedures. Table 4 shows the
metal concentrations remaining in the final
effluents. The concentration of metal
added to each system was 5 mg/1 except for
mercury, which was 0.5 mg/1. For com-
parison, the U.S. EPA water quality
criteria for metals in potable water
sources are also shown.
TABLE 4 RESIDUAL METALS
CONCENTRATIONS FROM THREE SYSTEMS, yg/1
Quality Iron Low Lime High Lime
Metal Criteria System System System
Mn
Ni
Zn
Cu
Cd
Ba
Pb
r III
Cr
r VI
Cr
As
Hg
50
5000
1000
10
1000
50
T 50
100
2
3820
37
192
155
50
271
30
6
21
58
235
38
561
169
44
25
29
16
87
915
37
12
584
352
14
942
19
18
76
770
54
Mechanisms of removal include
precipitation as hydroxides, hydrous oxides,
carbonates and sulfates with subsequent
removal by sedimentation and filtration.
Activated carbon also removes certain metals
by adsorption. These carbon columns were
anaerobic, thus providing a suitable
environment for the reduction of sulfate to
sulfide. The concentration of sulfide was
widely variable but precipitation and
filtration of the heavy metals as the in-
soluble sulfide must certainly have
occurred in the carbon columns.
Phase 2 (3)
After completion of the first phase of
the metals study and the chemical pre-
treatment study discussed previously, the
pilot plant underwent major revision. The
flow scheme remained essentially the same,
but changes were made in the equipment.
The clarifiers were made deeper to allow
greater detention time. The 4-in (10 cm)
carbon columns were replaced with two
5.75 in (14.6 cm) columns in series. The
depth of carbon in each column was 8 ft
(2.4 m) for a total carbon depth of 16 ft
(4.9 m). The hydraulic loading was
4 gal/min/sq ft (10 m/hr) resulting in
30-min contact time (based on empty bed
volume).
During the second phase of the metals
study, the raw sewage was spiked with some
of the less common metals. The clarifier
was operated using either iron (ferric
chloride, 40 mg Fe/1), lime (415 mg
Ca(OH)2/l, pH 11.5) or alum (220 mg/1).
The data are summarized in Tables 5, 6 and
7. It can be seen that most of the metal
removal occurs in the chemical clarifica-
tion step. However, carbon does remove a
significant fraction of some of the metals
applied. For example, in improving the
removal of mercury from 94% to 98.3%
(Table 5), the carbon reduced the residual
concentration from 3.6 ppb to 1 ppb, 56%
removal across the carbon. Table 6 shows
that where lime was not particularly
effective for mercury, antimony, selenium,
thallium, and vanadium, carbon increased
the total removal significantly.
This project has now produced a large
body of data relating to the fate of many
heavy metals in independent physical-
chemical treatment processes. The com-
bination of chemical clarification,
filtration and activated carbon adsorption
is effective for the removal of most heavy
metals, assuming the proper choice of
chemical. Molybdenum, for example, was not
removed by alum or lime, but the ferric
chloride-carbon process gave 80% removal.
The metal residual after clarification and
filtration should be somewhat predictable
580
-------
TABLE 5
METALS DATA SUMMARY, ALUM COAGULATION
Initial
Metal Oxidation Concentration
State PPM
Cumulative % Removal
PPB Residual
Metal
Clarifier Filter Carbon Carbon
Silver +1
Beryllium +2
Bismuth +2
Cobalt +2
Mercury +2
Molybdenum +6
Antimony +3
Selenium +4
Tin +2
Titanium +4
Thallium +1
Vanadium +5
Manganese +2
Nickel +2
Zinc +2
Copper +2
Cadmium +2
Barium +2
Lead +2
Chromium +3
Chromium +6
0.6
0.1
0.6
0.8
0.06
0.6
0.6
0.5
0.6
0.6
0.6
0.5
0.7
0.9
2.5
0.7
0.7
0.5
0.6
0.7
0.7
based on solubility products and jar tests.
Carbon provides additional removal of most
metals, the extent of which can best be
determined by pilot column operation.
Effects of pH on Removal of Organics from
Wastewater
by Activated Carbon
95
93
92
47
88
4
61
53
92
95.3
33
86
31
25
1
70
43
87
91
93
61
96.9 99
98.1 98
95.5 96
49 56
94 98
0 10
62 71
48 56
95 . 3 94
>95.8 >95
31 39
94 >99
30 33
25 37
1 28
67 98
45 55
79 92
95.5 96
97.6 99
64 97
.2 5
.9 1
.9 19
352
.3 1
540
174
220
36
.8 <25
366
.5 <3
469
569
1800
.3 12
.5 312
40
.6 20
.3 5
.4 18
were different for different conv
The manipulation of pH is not un
physical-chemical systems, occur
lime clarification and neutraliz
also incidentally when using the
salts, ferric chloride or alum.
justment of pH is a relatively e
Early research on activated carbon
treatment of secondary effluent seemed to
indicate that adsorption of refractory
organics improved with decreasing pH.
Later work, however, showed that pH effects
operation. Thus, a P-C carbon system
could easily be operated at any reasonable
pH if adsorption were improved.
One of the Cincinnati P-C pilot plants
was outfitted to provide data on the
581
-------
TABLE 6--METALS DATA SUMMARY, IRON COAGULATION
Metal
Silver
Beryllium
Bismuth
Cobalt
Mercury
Molybdenum
Antimony
Selenium
Selenium
Tin
Titanium
Thallium
Vanadium
Metal
Silver
Beryllium
Bismuth
Cobalt
Mercury
Molybdenum
Antimony
Selenium
Selenium
Tin
Titanium
Thai I ium
Vanadium
Oxidation
State
+1
+2
+ 2
+ 2
+ 2
+ 6
+ 3
+4
+ 4
+ 2
+ 4
+ 1
+ 5
TABLE 7--
Oxidation
State
+ 1
+ 2
+ 2
+ 2
+ 2
+ 6
+ 3
+4
+4
+ 2
+ 4
+ 1
+ 5
Initial PFB Residual
Concentration Cumulative °o Removal Metal
PPM
Clarifier Filter Carbon Carbon
0 . 5 94
0.1 93
0.5 83
0.5 27
0.05 92
0.6 66
0.5 60
0.1 66
0.05 68
0.5 95
0.5 84
0.6 36
0.5 93
METALS DATA SUMMARY, LIMP, C
98.2
94
94
18
98
6S
65
75
80
98.0
87
30
97.2
99.1
98.9
96.2
30
99
80
72
80
75
98 . 5
90
45
97.8
5
1
19
350
<1
120
140
20
13
8
50
330
11
0 Anil I, AT I ON
Initial
Concentration Cumulative "« Remov
PPM
Clarifier Kilter C
0.5 95.8
0.1 97.8
0.6 90
0.5 90
0 . 5 4 5
0.5 NO RP.MOVAI
0.6 21
0.5 36
0 . 06 4 6
0 .5 91
0.5 92
0.5 54
0.5 55
97.1
99.4
95.3
91
70
•
28
35
38
92
95 . 5
60
57
al
a rbon
98
99.5
96
95
91
52
95
67
92
95 . 3
72
91
PPB Residual
Metal
Carbon
.10
1
24
25
45
288
25
20
40
24
140
45
582
-------
influence of pH on carbon performance. Raw
sewage was clarified with 194 mg alum/1.
The dosage was manually adjusted to main-
tain pH 6.4 ± 0.2. After dual-media
filtration at 3.9 gal/min/sq ft (9.5 m/hr),
the effluent was split into three streams.
The pH's of two of the streams were ad-
justed to 4.0 and 8.8, respectively, and
pumped to separate carbon adsorbers. The
third stream was pumped at ambient pH (6.4)
to a third adsorber. These were identical
adsorbers treating the same wastewater at
three different pH's. The adsorbers were
5.75 in (14.6 cm) two-stage series with
8 ft (2.4 m) of Filtrasorb 300 carbon per
stage for a total carbon depth of 16 ft
(4.9 m). The hydraulic loading was 6 gal/
min/sq ft (15 m/hr) resulting in 20 min
total empty bed contact time. Sodium
hydroxide and sulfuric acid were injected
by pH controlled metering pumps into the
carbon column feed streams upstream of
in-line mixers. There was no difficulty
maintaining constant pH.
Table 8 shows the results of the alum
clarification-filtration treatment of raw
sewage over the six months study. Alum
clarification-filtration was highly
effective for removal of total organic
carbon (TOG), suspended solids (SS),
phosphorus (P) and turbidity. Around 40%
removal of soluble TOC (STOC), color and
total Kjeldahl nitrogen was observed.
Operation of the carbon columns at
pH 4.0, 6.4 and 8.8 did produce varying
results. Figure 7 shows breakthrough of
TOC with throughput. The low pH system
performed poorly from the start, and was
exhausted rather quickly. The high pH
system provided the best effluent through
most of the study. There was an apparent
alteration of the wastewater caused by
elevating the pH to 8.8. This was
evidenced by much higher solids con-
centration in the carbon column backwash
water than from the others. This led to
the suspicion that precipitation and
filtration of soluble or colloidal organics
was providing improved removal. However,
analysis of data on the ratio of particu-
late TOC to total TOC showed no significant
difference at the three pH's. The per-
formance of the column which received pH
6.4 wastewater was poorer than the high
pH column at the beginning, but declined at
a slower rate, indicating the development
of some biological activity as the study
progressed. The pH 6.4 column was the only
one which discharged any sulfide (0.5 mg/1),
indicating a more suitable environment for
biota than the other two. Biological
activity was probably not a major factor
because of the low feed organics (15 mg
TOC/1) and the fact that the beds were kept
very clean by daily air-scour, water
backwash.
TABLE 8 - POLLUTANT REMOVAL BY ALUM CLARIFICATION AND FILTRATION
Parameter
Raw Sewage
After Clarification
and Filtration
% Removal
TOC, mg/1
STOC, mg/1
SS, mg/1
Color, units
P, mg/1
Alk. , mg CaC03/l
Turbidity, units
NH3, mg N/l
TKN, mg/1
96.1
23.6
235
42
7.3
186
84
11.2
21.3
15.1
13.5
7.8
25.4
0.3
101
5.2
11.1
12.6
84
43
97
40
96
-
94
-
41
583
-------
1.0
0.8
O)
c
0.6
O
O
0.4
2 0.2
_ BREAKTHROUGH OF TOC
pH 6.4
2 4 6 8 10 12
Volume Treated (1000 Bed Volumes)
Figure 7. Breakthrough of TOC.
After the six-months study was com-
pleted samples of carbon from the first
eight feet of each system were subjected to
thermogravimetric analysis. Weight loss
at 475°C in a nitrogen atmosphere was
measured. The pH 6.4 and 4.0 system spent
carbon samples showed approximately equal
weight loss, while the weight loss of the
pH 8.8 spent carbon sample was about 50%
higher. While this measurement may not
correlate quantitatively with organics
adsorbed on the spent carbon, it does
indicate that the higher pH was favorable
for adsorption of the organic materials in
the wastewater studied. It also indicates
little difference in adsorption at pH 4.0
and 6.4, implying that the obvious improve-
ment in removal at pH 6.4 over pH 4.0 might
be the result of biological activity. This
weight loss analysis is very limited data,
and the implications suggested here are
only speculative.
Figure 8 illustrates the results of a
data analysis similar to that outlined
earlier for the study on effects of chemical
pretreatment. Cost analysis assumptions
are the same as those used earlier and as
shown in Table 3. This shows total carbon
treatment cost as a function of effluent
TOC. At low effluent TOC requirements,
operation at the higher pH is the obvious
choice. At less stringent effluent
standards (<50% removal across the carbon),
there is little to choose between the pH
6.4 and 8.8 operation. Operation of a
COST OF CARBON TREATMENT
(June,1974)
4 5 6 7 8 9 10
Eight Contactor Blended Effluent TOC, mg/l
Figure 8. Cost of carbon treatment.
carbon column at low pH is not indicated
for this wastewater.
Formation and Removal of Chloro-organics
in a Tertiary Breakpoint Chlorination-
Activated Carbon System
At the request of EPA Region III, EPA
Cincinnati is1 undertaking an extensive
pilot study of the formation of chlorinated
organics during the process of ammonia
removal by breakpoint chlorination (BPC).
Region III has awarded a construction grant
to the Washington Suburban Sanitary Com-
mission (WSSC) for the construction of a
60 mgd (230,000 cu m/day) advanced waste
treatment plant in Montgomery County,
Maryland. Region III is in the process of
preparing an Environmental Impact Statement
for the Montgomery County facility. The
question of the extent of formation and
removal of chlorinated organics during the
breakpoint process was encountered because
of recent innovations in analytical
chemistry which disclosed the presence of
these possible carcinogens in many
municipal water supplies. Since the
Montgomery County plant effluent will dis-
charge to the Potomac upstream of the
drinking water intake of Washington, D.C.,
Region III asked MERL to supply data to
indicate the extent of the chloro-organics
problem likely to be encountered.
A brief preliminary study was con-
ducted wherein batches of lime clarified
and filtered secondary effluent were pump-
ed through a BPC system followed by a short
contact time (2-1/2 min) carbon column.
This was done to provide quick data to the
Region, recognizing the limitations of poor
584
-------
chlorination control and unrealistic
operating parameters. During eight days of
operation BPC and short contact carbon
treatment produced the results shown in
Table 9. Only chloroform was detected
above 1 yg/1 in the lime clarified and
filtered activated sludge effluent. Only
small quantities of the haloforms were
found after breakpoint with the exception
of chloroform and bromodichloromethane.
The concentrations for these two compounds
are in the same range as values observed
by others in the City of Cincinnati tap
water (45 yg chloroform/1 and 13 yg
bromodichloromethane/1). The TOC of the
lime clarified-filtered secondary effluent
was 10 mg/1.
During the eight days of this study-,
the carbon was effective in removing the
small amounts of halomethanes formed by
chlorination, with the exception of
chloroform. Figure 9 shows the formation
and removal of chloroform. Breakthrough
from the carbon column began on about the
second day and continued to complete
breakthrough on the last day of the run.
The chloroform loading at complete break-
through was 73 yg CHClj/g carbon.
While the preliminary study discussed
above was being carried out, the P-C pilot
plant formerly used for the study on effects
of pH was being revised for an extensive
100
80
60
oi
=L
_
O
O
40
20
01 234 56 7 8
Days
Figure 9. Formation and removal of chloroform.
study of the BPC-carbon system. Trickling
filter effluent will be supplied as pilot
plant feed. Lime feeding and acid neutrali-
zation controlled by automatic pH equipment
was installed. Again, three parallel
TABLE 9 FORMATION AND REMOVAL OF VOLATILE CHLORINATED ORGANICS
Feed
CHC13
C H Cl ^
242
BrCHCl2
Br2CHCl
CHBr3
1-12
ND
ND
ND
ND -
(4
0.
<0
<0
<0
avg.)
7
.1
.1
.1
B.P.
11-96
ND 2
<0.1
ND 0
ND 0
Cl? Eff.
(40 avg.)
.5
22
.3
.8
Carbon Eff.
0.1
ND
ND
ND
ND
— >
- 0.
- 0.
- <0
- <0
breakthrough
2
3
.1
.1
(a) Single peak for C-H.Cl- and CC1. - expressed
(b) ND - no peak observed
(c) <0.1 detectable but too small to quantify
(d) All values yg/1
(e) Three grab samples per day
585
-------
carbon systems will be used to treat filter
effluent. One will incorporate a BPC
system between the filter and the first
stage of carbon. The second will have a
BPC system installed between the first and
second stages of the carbon system. The
third carbon adsorber will not have a BPC
system.
The ammonia content of the influent to
each BPC system will be monitored by a
Technicon Auto Analyzer. The ammonia
concentration will be transmitted as an
electrical signal to a sodium hypochlorite
feed pump controller. This will cause the
feed pump to add chlorine at a predetermined
ratio to achieve breakpoint. Success of
ammonia oxidation will be monitored by
analyzing effluent streams after carbon
treatment. Free and total chlorine will
also be measured by the Auto Analyzer at
various points in the system. The pH of
the chlorination reactions will be
controlled automatically. The carbon
systems will be operated upflow with
8 ft (2.4 m) of Filtrasorb 400 per stage
for a total depth (at repose) of 16 ft
(4.9 m). The hydraulic loading will be
6 gal/min/sq ft (15 m/h) for a total
contact time of 20 min (based on empty bed
volume, carbon at repose).
As soon as the major process equipment
revisions could be completed, one BPC
system was operated for a period of three
weeks with manual control of the chlorine
feed rate. The BPC system that preceded
carbon treatment was the one chosen for
this run. The operator would take the
ammonia reading from the on-line Auto
Analyzer and manually set the hypochlorite
feed pump to deliver the appropriate
chlorine dose. Free and total chlorine
were measured amperometrically and the
carbon effluent ammonia content was
monitored by the in-line Auto Analyzer.
The data from the three-week run have,
as of this writing, not yet been completely
analyzed. However, certain preliminary
observations can be made. The halo-
methanes were formed at concentrations
somewhat higher than observed earlier. The
feed to the BPC system varied considerably.
from 5 yg/1 to 250 yg/1. Figure 10 shows
the chloroform concentration in the influent
to the carbon system (after BPC), the
effluent from the first stage carbon and
the effluent from the second stage carbon
column. Breakthrough of chloroform through
250 r
200 -
150 -
O)
a.
_
o
i
o
100 -
50 -
N.D.
•tage Effluent
Final Effluent
Figure 10. Chloroform removal by activated carbon.
the first 8 ft (2.4m) of carbon began very
quickly. However, the final effluent never
exceeded 10 yg/1. This could indicate that
contact times longer than 10 min are re-
quired for efficient chloroform removal.
This question will be addressed in more
detail in future work.
The data showing that effluent from
the first stage carbon at times was higher
than the influent implies that the adsorp-
tion of chloroform is easily reversible.
This will also be investigated further.
When all the automatic control
equipment is installed, the three carbon
systems will go on-stream continuously in
order to provide data on not only the
formation and removal of halomethanes, but
also on the oxidation of ammonia with
chlorine, the effect of chlorine on carbon
life, and control and operational problems
involved with the BPC system. Questions
on the halomethane problem that will be
answered include:
1. Correlation between chlorine dose
or residual and halomethane production.
586
-------
2. Effect of precursor removal on
halomethane production (BPC after first
stage carbon).
3. Capacity of carbon to remove
halomethanes.
4. Influence of carbon contact time
on removal of halomethanes.
Enhancement of Granular Activated Carbon
Performance by the Addition of Nitrate
Under contract with EPA, the Los
Angeles County Sanitation District con-
structed and operated a 50 gal/min (3.2
I/sec) P-C pilot plant at Pomona,
California (4). The system consisted of
chemical clarification of raw sewage using
alum and polymer followed by treatment in a
downflow carbon column. Performance and
system parameters are shown in Table 10.
The major objective of the project was to
learn what problems could result from long
term treatment of chemically clarified raw
sewage. It was realized that biological
growths in the P-C carbon systems might
cause severe problems of plugging and/or
sulfide generation. Thus, the Pomona
project was designed to quantify these
effects and to investigate measures to
alleviate the problem conditions, should
TABLE 10 - POMONA P-C-T PILOT PLANT
Parameter
TCOD, mg/1
DCOD, mg/1
SS, mg/1
Turb., JTU
BOD5, mg/1
Color units
P, mg/1
N03, mg N/l
PH
Clarifier
Raw Sewage
321
49
199
11.1
7.7
Clarifier Eff1.
96
49
28
23
36
20
1.3
0.9
6.8
Carbon Eff1,
19
14
7
6
0.9
1.3
6.8
Flow 60 gal/min (3.8 I/sec) constant
Overflow Rate - 1180 gal/day/sq ft (48 cu m/day/sq m)
Weir Loading - 10 gal/min/ft (2 1/sec/m)
Detention Time 84 min
Alum Dose 25 mg Al/1
Polymer Dose - 0.3 mg/1 - anionic
Sludge Production - 2000 Ib/mil gal (250 mg/1)
Granular Carbon
Flow 50 gal/min (3.2 I/sec) constant
Hydraulic Loading 4 gal/min/sq ft (10 cu m/hr/sq m)
Contactor Type - Single Stage Packed Bed Downflow
Carbon Size 8x30 mesh
Carbon Depth 16 ft (4.9 m)
Empty Bed Contact Time 30 min
Sodium Nitrate Dose 33 mg NaNOj/l
1st Cycle Carbon Loading - 3.5 g TCOD removed/g carbon (1.5 g DCOD/g)
1st Cycle Carbon Utilization rate < 173 Ib/mil gal (21 mg/1)
Note: Carbon column ran 18 months (1st cycle) prior to regeneration
and was not exhausted. Three regeneration runs were conducted
in order to obtain regeneration data. Performance data shown
above is average data over entire 27-month operation.
587
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they appear. Of course, process per-
formance would also be monitored. Another
important objective was to obtain data
on the regeneration of P-C carbon, which
would likely be heavily loaded with or-
ganics and possibly carry biological slimes.
As expected, hydrogen sulfide appeared
in the carbon effluent after several weeks
on stream. Table 11 shows the measures
used in attempting to eliminate the sulfide,
including backwash methods, aeration or
chlorination of carbon influent and nitrate
addition. The final solution was the ad-
dition of 33 mg NaNOj/l. Nitrate is
reduced to nitrogen gas and the resulting
oxygen is used as hydrogen acceptor in the
biochemical utilization of substrate.
Nitrate addition caused additional pressure
drop, but it was within the design pressure
capacity of the system. The increase in
headless during a 24-hour run between
backwashes was always less than 50 psi
(340 k N/sq m) and on the average less
than 30 psi (210 k N/sq m). A welcome
result of the nitrate addition at Pomona
TABLE 11 PERFORMANCE OF THE VARIOUS H2S CONTROL
AT POMONA
H S Control Methods
2
(1) Surface wash Backwashing
Technique
(2) No. (1) Plus intermittent
02 addition to carbon
column at D.O. level
= 4 mg/1
(3) Surface wash + Air/water
backwash plus oxygenation
of the chemically clari-
fied effluent to D.O. 2-6
mg/1
(4) No. (3) + 20 mj,/l Cl2a
added to carbon influent
(S) No. (3) + 40 mg/1 C12
added to carbon influent
(6) No. (3) + 2.9 mg/1 N b
added to carbon influent
(7) No. (3) + 4.5 mg/1 N
(8) No. (3) + 5.1 mg/1 N
(9) No. (1) + 5.3 mg/1 N
10) No. (1) + 5.4 mg/1 N
Carbon Effluent Total Sulfide,
Cone. , mg/1 S
Average
2.86
1.85
1.87
1.74
1.13
0.3
0.13
0.05
0.019
0
Range
1.0 5.7
1.4 2.5
0.8 3.0
0 4.3
.09- 2.6
0 .95
0 0.60
0 .26
0 .10
0 .05
a added as sodium hypochlorite solution
b added as sodium nitrate solution
588
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and one not entirely expected was an
apparent indefinite extension of the life
(capacity) of the carbon. The carbon
column was operated for 18 months with-
out replacement and without a significant
decline in organic removal efficiency.
The apparent carbon loading during that
time reached a phenomenal 3.5 g COD re-
moved/g carbon of which 1.54 g/g was
soluble COD. Considering that values in
the range of 0.5 g COD removed/g carbon
are commonly accepted for carbon loading
in physical-chemical systems, it is
apparent that the mechanisms of filtration
(particulate COD "loading" was 3.5-1.5
= 2 g/g) and nitrate assisted biological
activity contributed greatly to the
organics removal.
In order that the Pomona experience
could be verified and expanded at another
location, the Lebanon pilot plant facility
is currently modifying an existing P-C
pilot system to run an upflow carbon column
on lime clarified-neutralized raw waste-
water. Sodium nitrate will be added prior
to the carbon column, and the performance
will be monitored for a long period of
time. It may be possible that nitrate
oxygen will enhance the biological activ-
ity within a carbon column such that the
replacement rate of the carbon is signifi-
cantly reduced or even eliminated.
FULL SCALE TREATMENT OF MUNICIPAL
WASTEWATERS BY ACTIVATED CARBON
There are several tertiary activated
carbon systems now in operation producing
effluents of reuse quality. South Tahoe
effluent is pumped to a reservoir which
is used for sport fishing and as an irri-
gation water supply. Colorado Springs
carbon effluent is used as power plant
cooling water. Orange County Water Dis-
trict, with a system similar to Tahoe's,
will inject the carbon effluent, after
blending with low TDS water, into the
underground aquifer to prevent salt water
intrusion. The use of reclaimed wastewater
(including carbon treatment) for augmenta-
tion of drinking water supplies is being
seriously considered in certain water-
short areas of this country. Direct pot-
able reuse has been routinely practiced at
Windhoek, South Africa.
The first full-scale facility in the
United States which treats a waste of pri-
marily domestic origin by only P-C proc-
esses is now on stream at Rocky River,
Ohio. This 10 mgd (38,000 cu m/day)
facility utilizes alum and polymer to
clarify raw sewage in existing primary
clarifiers which have been equipped with
internal flocculation mechanisms. Clari-
fier effluent is then pumped through a
bank of eight parallel carbon adsorbers.
The carbon effluent is then discharged to
Lake Erie. The Research and Development
Program of EPA and its predecessor organi-
zations has helped to finance the con-
struction of the activated carbon facility
via an R&D grant. Following the shakedown
and upon initiation of full flow through
the carbon system, a one-year evaluation
period will begin. Complete records of
operating conditions and performance will
provide essential information on the
effectiveness of the P-C system at full
scale. Extensive cost and time accounting
will allow determination of the actual cost
of the system and all subsystems. The man-
hour requirements for operational duties,
preventative maintenance and unscheduled
maintenance will be catalogued so that the
data will be relevant not only to this
combination of processes but to any other
system containing one or more of the proc-
esses used at Rocky River.
After the one-year evaluation period
the performance, operating and cost data
will be compiled in a technical report.
At that time, the U.S. consulting engineers
and wastewater treatment agencies will have
access to the experience and data gathered
at the first full-scale P-C facility. This
will be a major addition to the body of
knowledge in the municipal wastewater treat-
ment field.
SUMMARY
The removal of organic materials from
municipal wastewater by activated carbon
has been practiced for several years in the
tertiary systems, and now is being demon-
strated in a P-C system. Much knowledge
has been gained over the last decade, and
carbon system design is no longer a mystery,
However, there is still much to learn about
the mechanisms of removal of exotic and
commonplace organic compounds by this
versatile adsorbent. The factors affecting
adsorption of specific compounds or classes
of compounds have not been fully defined
nor have methods of prediction of adsorp-
tion performance.
589
-------
As technology develops and more and
varied organic materials enter and are
detected in the water environment, acti-
vated carbon can be expected to assume
an expanding role in environmental pro-
tection.
References
1. Westrick, J.J., and Cohen, J.M.,
"Comparative Effects of Chemical
Pretreatment on Carbon Adsorption."
Presented at the WPCF 45th Annual
Conference, Atlanta, Georgia,
(Oct. 1972). In Press.
2. Maruyama, T., Hannah, S.A., and
Cohen, J.M., "Metal Removal by
Physical and Chemical Treatment
Processes," Jour WPCF, 47, 962
(May 1975).
3. Hannah, S. A., Jelus, M., and Cohen,
J.M., "Removal of Uncommon Trace
Metals by Physical and Chemical
Treatment Processes." Presented at
the 48th Annual Conference, WPCF,
Miami Beach, Florida (Oct. 1975).
4. Directo, L.S., Chen, C.L., and
Kugelman, I.J., "Pilot Plant Study
of Physical-Chemical Treatment."
Presented at the 47th Annual Con-
ference, WPCF, Denver, Colorado,
(Oct. 1974).
590
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NEW INDUSTRIAL WASTEWATER
SEPARATION PROCESSES DEVELOPED UNDER THE
EPA RESEARCH PROGRAM
J. Ciancia
Industrial Environmental Research Laboratory-Cincinnati
Edison, New Jersey 08817
ABSTRACT
This paper describes the Industrial Research and Development Program of the U. S.
Environmental Protection Agency followed by a brief discussion of an approach companies
should use for abating pollution at manufacturing plants. Separation technologies in-
volving chemical recovery and/or wastewater reuse that have been developed under the
Industrial R§D Program of EPA are then discussed. The technology developments covered
are (1) a novel ion exchange technique for separating acids from metals to permit the re-
use of spent processing baths, (2) an ion exchange process for recovering chromate from
pigment manufacturing wastewaters, (3) the development and in-plant demonstration of
reverse osmosis and electrodialysis for recovering chemicals and reusing water from rinse
waste discharges in the metal finishing and fabricating industries, (4) a novel approach
for increasing the heat and mass transfer while also preventing scaling in vertical tube
evaporators and its demonstration on a pilot plant scale for several inorganic wastewaters,
and (5) a closed-loop type treatment approach involving electrolytic copper recovery, pro-
cess changes and integrated chemical treatment of rinse waters that have been applied on
a full scale for abating pollution at a copper and brass wire mill.
INTRODUCTION
The significance and complexity of the
industrial pollution problem coupled with
recent governmental legislation has spur-
red the development of new and improved
technology for treating and/or recovering
the multitude of wastes that spew from the
Nation's industrial plants.
With the passage of the Clean Water
Restoration Act of 1966, the U. S. Environ-
mental Protection Agency assumed a key
role in the development of more effective
and economical technology for treating
industrial wastes. Under the provisions
of this Act, EPA initiated a program to
develop and demonstrate new and improved
technology for the prevention, control,
treatment, recovery and reuse of industri-
al wastes. The Agency's authority to de-
velop improved industrial and joint indus-
trial/municipal wastewater treatment
systems was expanded with the passage of
the Federal Water Pollution Control Act of
1972. Moreover, this legislation estab-
lishes closed-loop type technology as the
direction to pursue in developing new pol-
lution abatement approaches by declaring
that it is the national goal to eliminate
the discharge of pollutants into the nav-
igable waters of the United States by 1985.
As a result, the EPA Research, Development
and Demonstration Program has become more
strongly oriented toward technology that
can accomplish chemical recovery and water
reuse at the same facility or through by-
product recovery of the waste materials.
The Industrial Research and Develop-
ment Program in EPA is carried out by in-
house efforts, grants and contracts. How-
ever, the bulk of the studies to date have
591
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been carried out through the grant and con-
tract mechanism, which permits the program
to utilize the best science and engineering
talent in the Nation's universities, private
research institutions, and industry.
The objectives of the program are to
assess the pollution problems and current
abatement practices in relation to the needs
of the industries, and support research,
development and demonstration studies in-
volving technology with a high potential for
solving the most significant problems at the
least cost and with a maximum amount of
chemical recovery and water reuse. To war-
rant support, it is necessary that prelim-
inary investigations show that the proposed
technology is technically feasible and more
attractive than existing commercial ap-
proaches for abating specific waste prob-
lems. Studies are supported at all stages
of development from the bench scale through
pilot plant and full scale demonstrations.
ABATEMENT OF INDUSTRIAL WASTE PROBLEMS
In approaching pollution control, each
plant must first define the problem by iden-
tifying all waste sources, including the
characteristics, volumes and pollutant loads
associated with each discharge. With the
problem defined, process change and in-plant
control techniques can now be considered
and implemented where feasible for conserv-
ing water and eliminating all unnecessary
wastes.
Since it is much simpler to recover
components before waste streams are combined,
and thus become complex mixtures of contam-
inants, the next step in a pollution control
program is to carefully assess the different
waste sources to explore the application of
closed-loop type technology. Where chem-
ical recovery and water reuse do not appear
to be feasible, the application of alterna-
tive treatment technology should then be
considered for the remaining waste streams
on an individual and/or combined basis to
meet governmental effluent requirements
with a minimum of capital, operating and
overall environmental costs.
NEW ABATEMENT TECHNOLOGY
The purpose of the remainder of this
paper is to provide some insight into closed-
loop type developments associated with EPA's
Industrial R&D Program and the application
of these approaches to industrial pollution
problems for achieving chemical recovery
and/or water reuse.
Ion Exchange
Unlike the widespread application
achieved in water treatment, the commercial
use of ion exchange for processing and waste
treatment has been rather limited. However,
there has been considerable interest in the
use of ion exchange as a pollution control
tool in the last several years. This stems
from a combination of factors, including
the intensified interest in pollution con-
trol, the capability of the technique to
recover chemicals and purify wastewater, and
the availability of improved ion exchange
resins.
Recently, a novel ion exchange tech-
nique for separating strong acids from metal
contaminants was shown to be economically
feasible for reclaiming phosphoric acid used
in the bright finishing of aluminum. Refer-
red to as "acid retardation," the technique
permits the separation of strong acids from
their salts by passage of the solution
through the corresponding salt form of a
strong base ion exchange resin. While the
mechanism of the process is not completely
understood, acid retardation separations
involve the preferential absorption of strong
acids on the resin which "retards" or slows
down the movement of these acids through
the bed relative to the salt. The acid
molecule is desorbed from the resin by
water, thus eliminating the need for chem-
icals to regenerate the ion exchanger as in
conventional ion exchange treatment processes.
The acid retardation process has been
optimized in pilot plant equipment using
actual phosphoric acid wastewater from
aluminum bright finishing production opera-
tions. The study utilized a continuous
countercurrent contactor to obtain maximum
efficiency in separating the phosphoric
acid from aluminum.
The pilot plant study showed that over
75% of the acid content could be recovered
from feed streams containing 25-35% phos-
phoric acid which is generally obtained in
the countercurrent rinsing of aluminum parts
after bright finishing. In this application,
the ion exchange resin accomplishes the
separation by absorbing the phosphoric acid
while the aluminum remains in the wastewaters
592
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and passes out the column in the effluent.
The acid is eluted from the bed with water,
concentrated by evaporation, and returned
to the bright finishing processing operation.
The economic evaluation of the process
based on the pilot plant results indicates
that the required capital investment could
be recovered in about 1.5 years when both
the cost of the recovered acid and alterna-
tive chemical waste treatment are considered.
For those plants where the 35% waste acid
can be returned to the supplier, the addi-
tional savings afforded by the "acid retar-
dation" system is estimated to return the
investment in approximately two years.
In another development, a new ion ex-
change approach has evolved for recovering
chromate and zinc from wastewaters discharged
from the manufacture of zinc yellow pigment.
A full scale in-plant demonstration showed
that the new waste abatement system is high-
ly effective and much more economical than
chemical treatment. In general, the tech-
nology for treating wastewaters from the
inorganic pigment industry is presently
limited to pH control, precipitation, and
removal of suspended solids by conventional
liquid/solid separation techniques.
The new approach involves passing the
mother liquor and wash waters through a
strongly basic anion exchange resin, which
reduced the chromate content of the waste-
water from 2,700 ppm to about 1-2 ppm in the
in-plant demonstration. The effluent from
the ion exchange column is neutralized with
sodium carbonate to precipitate the zinc.
The insoluble zinc carbonate is removed by
filtration and then dried for sale. Regen-
eration of the ion exchange column is
accomplished with a heated alkaline salt to
remove the chromate which is reused in the
manufacturing operation.
When considering the costs associated
with conventional chemical treatment (includ-
ing sludge disposal) and the savings from
the recovered chromate and zinc, the compa-
ny estimated that only 2-3 years would be
required to amortize the capital expenditure
of $125,000 for the ion exchange system.
It was also concluded from the study that
the new ion exchange approach has potential
for economically treating other chromate
pigment manufacturing wastewaters.
Membrane Technology
The U.S. Environmental Protection Agency
has an extensive extramural program underway
to develop and demonstrate new membrane tech-
nology for abating pollution from metal fin-
ishing and nonferrous metal fabricating
plants. Techniques such as reverse osmosis
and electrodialysis are attractive approaches
for treating rinse wastes. When used on
individual rinse waters, this type of tech-
nology can accomplish simultaneous concen-
tration of the chemicals for return to the
processing bath while purifying the waste-
water for reuse in the rinsing operation.
The reverse osmosis studies may be grouped
into three categories. The first, which has
been completed, involved testing all com-
mercially available membranes and configu-
rations on the various major types of rinse
waters. In another phase of the program,
new membranes with improved properties are
being tested, especially those which have
the potential for expanding the application
of RO to higher and lower pH conditions as
well as oxidizing contaminants. The remain-
der of the program involves carrying out
full scale demonstrations under actual plant
conditions where attractive applications have
been identified in order to firmly establish
the economic feasibility of the approach for
the particular rinse waste.
At the present time, cellulose acetate
in several configurations and hollow fiber
polyamide are the only reverse osmosis mem-
branes that are commercially available for
use in the treatment of industrial waste-
waters . In the pilot plant study, extensive
tests were carried out on the use of cel-
lulose acetate tubular and spiral wound and
hollow fiber polyamide membranes for treating
the major metal finishing rinse waters. Re-
verse osmosis was found to be generally
applicable except for oxidizing conditions
such as are encountered with chromic acid,
and high and low pH rinse waters. The study
showed that the hollow fiber polyamide mem-
brane is suitable over a pH range of 4 to
11 and that the cellulose acetate spiral
wound and tubular membranes have reasonably
good operating lives from pH 2.5 to 7.
Based on the pilot plant investigation
and subsequent demonstrations under actual
plant conditions, reverse osmosis has been
shown to be a feasible treatment/recovery
technique for metal finishing rinse waste-
waters. However - the field demonstrations
593
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also underscore the need for some prelim-
inary investigation prior to deciding on the
use of reverse osmosis because of the com-
plex nature of the processing baths which
generally contain proprietary additives.
The field demonstrations were carried
out on copper cyanide rinse wastes at two
plants and nickel plating rinse waste at one
location using a hollow fiber polyamide mem-
brane system. Although no problems were
encountered in the pilot plant studies,
which used actual plating baths that were
diluted to rinse water concentration, the
membrane significantly declined in perfor-
mance at one of the two plants where the
system was used to treat copper cyanide
rinse wastewater. Subsequent laboratory
investigations indicated that the decline
in performance was due to some extent to the
degradation of the spacer (used for flow dis-
tribution within the module) by the bright-
ener additive to the bath. At the other
location, however, the flux and rejection
achieved by the membrane were relatively
stable and the system performed satisfacto-
rily over a sufficient time to conclude that
reverse osmosis would be a viable treatment
approach for copper cyanide rinse waste-
waters. The field test on nickel plating
rinse wastes established the feasibility of
using hollow fiber polyamide membranes for
treating this type of rinse water. More-
over, there have been a number of commercial
installations of cellulose acetate reverse
osmosis systems for the treatment/recovery
of nickel plating rinse wastewaters over
the past several years, but the success of
this application has never been fully doc-
umented.
The application of reverse osmosis for
closing the loop on metal finishing rinse
wastes is shown on Figure 1. Rinse water
from the first tank, which would otherwise
be discharged to the drain, is separated by
the reverse osmosis system into a "concen-
trate" and "permeate" stream. The concen-
trate stream is returned to the processing
bath, and the purified or permeate stream
is recycled to the rinsing operation. A
small evaporator is required for those metal
finishing operations where insufficient nat-
ural evaporation occurs in the bath.
WATER MAKEUP
EVAPORATION
DRAG-IN
EVAPORATOR
(WHERE NEEDED) {
CONCENTRATE
PURIFIED WATER (PERMEATE)
Figure 1
REVERSE OSMOSIS RECOVERY SYSTEM
The major features of reverse osmosis
as a treatment device for metal finishing
rinse waters are low capital and energy
costs, simplicity of operation, and compact
equipment requiring a minimum of space.
The modular nature of these units makes them
particularly attractive for small scale
installations.
Electrodialysis is an established water
treatment and processing technique which is
now starting to receive recognition in the
industrial waste treatment field.
Based on a number of pilot plant in-
vestigations, the system has been shown
to be attractive for purifying metal finish-
ing rinse wastewaters for reuse in the rin-
sing operations while concentrating the
chemicals for return to the processing bath.
In a. pilot plant study supported by
EPA, a prototype electrodialysis system was
used to demonstrate the feasibility of treat-
ing and recovering the chemicals from a cop-
per cyanide rinse wastewater. Figure 2
shows the application of the electrodialysis
system for achieving closed-loop control
of metal finishing rinse wastewaters.
594
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WORK DRAGOUT
r—-„ _,
I
I
I
METAL FINISHING TANK
I I
.j L.
ELECTRODIALVSIS UNIT
ELECTRODIALYSIS UNIT
Figure 2
ELECTRODIALYSIS RECOVERY SYSTEM
The study showed that the chemicals in
the rinse water could be concentrated to
over 70% of bath strength. For copper cya-
nide plating, this level of concentration is
sufficient to return all of the chemicals to
the processing operation since the bath is
operated hot and a significant amount of
natural evaporation occurs. The ability of
electrodialysis to achieve high levels of
chemical concentrations should permit the
process to economically close the loop on a
number of rinse wastewaters without the need
for additional evaporation.
There have recently been a few full
scale installations of electrodialysis in
metal finishing plants but no data are avail-
able at this time for evaluating the feasi-
bility of the technique for achieving closed-
loop type control under actual production
conditions.
Evaporation
The use of evaporation for treating in-
dustrial wastewaters to accomplish water re-
use and dissolved solids concentration for
simplified disposal or chemical recovery is
increasing throughout industry in the United
States. The evaporative technique has par-
ticular application in the inorganic chemical
industry where many wastes cannot be effective-
ly and/or economically treated by the com-
monly used waste abatement methods. More-
over, in many cases, closed-loop type tech-
niques such as reverse osmosis, electrodialy-
sis and ion exchange cannot achieve the de-
sired concentration and require the use of
an evaporator.
Based on the success achieved in the
desalting of seawater, a pilot plant investi-
gation has been carried out on a new evapo-
rative technique for industrial wastewater
treatment. The approach involves the use of
a small amount of surfactant to enhance the
heat and mass transfer of vertical tube
evaporators while also preventing scaling,
fouling and corrosion of the heat transfer
surface. The addition of surfactant to the
feed achieves enhanced evaporative heat trans-
fer by maintaining a thinned and agitated
liquid film on the heat transfer surface,
which also results in increased mass trans-
fer by extending the liquid to vapor sur-
face as shown on Figure 3.
UPFLOW VTE WITHOUT INTERFACE ENHANCEMENT
RESISTANCE TO THE FLOW OF HEAT R
*
RESISTANCE TO
HEAT FLOW
UPFLOW VTE WITH INTERFACE ENHANCEMENT
RESISTANCE TO THE FLOW OF HEAT R
Figure 3
CONVENTIONAL versus INTERFACE ENHANCEMENT EVAPORATION
The study involved the use of a 5,000
gal/day pilot plant having double fluted
aluminum brass distillation tubes for treat-
ing power plant cooling tower and boiler
blowdown. The use of surfactant to achieve
upflow interface-enhanced Vertical Tube
Evaporation provided approximately a 120%
increase in heat transfer compared to con-
ventional operation. Another important
benefit of the surfactant addition was its
ability to inhibit the crystallization of
solutes, which permitted the concentration
of the wastewaters to smaller volumes.
The results of this study indicate that
the new approach to evaporation has consid-
erable potential for the treatment of indus-
trial wastewaters, especially where scaling
may be a problem. With significantly in-
creased heat transfer, the size of new
595
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evaporators can be greatly reduced or exist-
ing systems can be utilized at much higher
capacities.
Electrolytic Recovery and Process Changes
A significant pollution problem at cop-
per and brass mills is the disposal of pick-
ling baths when the processing solution be-
comes ineffective due to the buildup of metal-
lic impurities. In addition,, large volumes
of dilute rinse waters containing acid, met-
als and other contaminants are produced in
the washing of the work following the pick-
ling operations.
A new approach to the treatment of cop-
per and brass mill wastes involves chemical
recovery and water reuse rather than neutra-
lization and precipitation of the pollutants
which requires considerable space and results
in a potentially troublesome sludge disposal
problem. The effectiveness and economics of
the new technology has been demonstrated on
full scale at a plant producing 75 tons of
copper and cuprous alloy per day which used
a hot sulfuric acid primary pickle followed
by an ammonium bifluoride secondary pickle.
The novel treatment approach, which is
shown on Figure 4, involved (1) the instal-
lation of an electrolytic copper recovery
system in the primary bath to recover the
copper and continuously purify the sulfuric
acid solution, (2) the replacement of the
chromic acid - ammonium bifluoride secondary
pickle with a hydrogen peroxide sulfuric
acid secondary pickle containing proprietary
additives, and (3) the incorporation of an
integrated chemical rinse system to wash the
wire prior to fresh water rinsing. The hy-
drogen peroxide oxidizing treatment in the
secondary pickling bath results in the for-
mation of water and a cupric sulfate buildup
which is periodically removed by simple
crystallization and added to the electrolytic
recovery system or sold separately as a by-
product. The integrated chemical rinse is a
recycle system in which the copper in the
pickling solution washed from the wire is
precipitated by the alkalinity in the rinse
water and settled as a salable dense sludge
in a reservoir tank.
REUSE WATER LINE
• 1 pLlli wwicn urc
,R20Z STABILIZER INHIBIT Hi I FROM DE_IONIZER r
P? ri'iO^ill^n.l^ii-j
to DRAWING
OPERATION
SETTLING TANK FINAL pH ADJUSTMENT TANK
Figure 4
PICKLING OPERATIONS, COPPER RECOVERY,
WASTE TREATMENT & WATER REUSE SYSTEM
The application of the recovery approach
has demonstrated a reduction of metal losses
from 600-700 to less than one pound per day
and water consumption from 200,000 to 20,000
gallons per day by chemical rinsing and
water reuse. Therefore, the new pollution
abatement system has eliminated the dumping
of spent pickling baths and the discharge
of such troublesome contaminants as chromium,
ammonium and fluoride, while permitting the
recovery of essentially all of the copper as
well as reuse of about 90% wastewater.
The company estimates that when the
cost of pickling and waste treatment for the
new approach is compared with the pickling
and waste costs of conventional chemical
treatment, a substantial savings has been
achieved -- a daily cost of$194 compared
with $540 for conventional abatement.
SUMMARY
In summary, new wastewater treatment
technology is emerging for chemical recovery
and water reuse but the extent of develop-
ments is relatively slow in comparison to
the overall needs of the Nation, primarily
because of the complexity of industrial pol-
lution problems. By continuing to support
596
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research, development and demonstrations of
innovative technology, as described in this
paper, the U. S. Environmental Protection
Agency intends to play a significant role
in the effort of attaining the national
goal of zero discharge.
597
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STATUS OF INSTRUMENTATION AND AUTOMATION
FOR CONTROL OF WASTEWATER TREATMENT PLANTS
J. F. Roesler
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
ABSTRACT
This paper addresses the questions about the effectiveness of instrumentation and
automation that is being used in wastewater treatment. A user survey of the instruments
and automatic controls being used in 50 wastewater treatment plants is described. The
instruments were evaluated on the basis of their usage and reliability. Automatic control
strategies were evaluated on the basis of their performance improvement and cost effective-
ness. Specific examples of control loops are described as implemented at Renton, Washing-
ton; Palo Alto, California; and the U. S. Environmental Protection Agency pilot plant at
Blue Plains Washington, D.C., automation for both biological and physical-chemical treat-
ment is discussed.
INTRODUCTION
The objectives of the instrumentation
and automation of any process are to
improve the reliability of maintaining a
consistent product quality, enhance process
performance and reduce costs. The concept
of applying instrumentation and automation
to wastewater treatment is still relatively
new, and as a result many questions must be
answered. Some of these questions are: 1)
what equipment is currently being utilized,
2) how effective is automated control and
3) what are the problems that must be over-
come to promote automation? Once the
answers to these questions are known,
productive utilization of instrumentation
and automation must be promoted.
In this paper an attempt will be made
to answer these questions by describing
some of the U. S. Environmental Protection
Agency (EPA) research results. This
research involves an EPA sponsored user
survey of 50 wastewater treatment plants,
the evaluation of several control strategies
at Palo Alto, California, inhouse efforts
evaluating dissolved oxygen (DOJ control at
Renton, Washington and EPA pilot plant work
on physical-chemical treatment in Washing-
ton, D.C. To maintain communication with
the user community the establishment of an
EPA advisory committee is also described.
CURRENT STATUS
In order to answer the first question,
a user survey of 50 wastewater treatment
plants (1) was conducted. Each plant was
personally visited by the interviewer who
determined the type and extent of usage
of instruments and automatic controls. In
each plant the operational personnel were
asked to give an estimate as to the effect-
iveness of the sensor or control loop. The
degree to which each instrument was used in
each plant and the operator's responses
were used to determine the effectiveness of
the equipment.
The present use of specific types of
sensors was evaluated by considering the
distribution of all types of sensors in all
50 plants as shown in Figure 1. Every
598
-------
plant had some device for monitoring flow.
Thus 30% of all the instruments in all of
the plants were for flow measurement
(Figure 1). Automatic analyzers were the
next highest category probably because this
category included, turbidity, conductivity^
* AUTOMATIC ANALYSIS
29%
* NON-LABORATORY PROCESS INSTRUMENTS ONLY
Figure 1. Observed distribution of measuring instruments
pH, DO, chlorine and other analyzers. The
miscellaneous analyzers section that is in-
dicated in Figure 1 include such analyzers
as rotational speed, weight, and position,
etc.
In Figure 2, the instruments observed
during the survey are summarized according
to the criteria of unsatisfactory
(abandoned equipment), fair (performance
considered marginal or excessive mainten-
ance is required) and satisfactory. Note
that with the exception of such devices as
the bubbler-type level detectors, Venturis,
temperature guages, etc., most instruments
suffered a 31% less than fair performance
record. Furthermore, instruments manufac-
tured by the same manufacturer and of iden-
tical model were abandoned at some loca-
tions but were utilized at other locations.
Note also that complicated equipment, such
as the TOC analyzers grouped in the "other
analytical analyzers" section, suffered
very high failure rates. Simple equip-
ment such as bubbler-type level detectors
performed well and were well integrated
into automatic control systems as shown in
Figure 3. Here liquid level is the most
popular of all observed control schemes.
With the exception of computers, as the
control scheme becomes more complicated
the number of poor experiences increase.
AUTOMATION OF ACTIVATED SLUDGE PROCESSES
To answer the second question as to
the effectiveness of automation, more
detailed studies are necessary. The
technique usually suggested for such an
evaluation is the comparison of the per-
formance of the plant under automatic
control with that of manual operation.
However, the standards for manual oper-
ation vary according to the idiosyncrasy
of each plant and of each operator. It is
therefore, necessary that the manual oper-
ation be well defined and rigidly enforced.
Two studies that meet these requirements
were carried out at Renton, Washington (2)
and Palo Alto, California (3).
The Renton plant was operated for
about a year (March 1970 to April 1971)
under manual control while an automatic
DO control system was being installed
into a new aerator. The following
year, the plant was successfully operated
with automatic DO control. Data were
collected for comparative purposes during
the months of October, November and
December for years 1970 and 1971. The
operators and plant management had an
excellent attitude toward automation.
Also, the manual control policy was well
defined and expertly carried out.
The obvious question, however, is
whether the sewage was identical for both
time frames. One partial answer is that
the BOD loading to the plant increased
about 50% during the automatic control
599
-------
10
1972-3
15
20
25
NO. OF CASES
30 35 40
BUBBLER-TYPE LEVEL DETECTORS
DIFFERENTIAL-PRESSURE LEVEL DETECTORS
FLOATS
ALL OTHER LEVEL DETECTORS
I WEIRS AND FLUMES
VENTURIS, ORIFICES, NOZZLES
MAGNETIC FLOWRATE
OTHER FLOWRATE METERS
I NUCLEAR RADIATION DENSITY METERS
TRANSMITTING RAIN GAUGES
I TEMPERATURE
PRESSURE
ROTATIONAL SPEED
WEIGHT
| POSITION
I TURBIDITY
CONDUCTIVITY
I PH AND ORP
THALLIUM DO PROBE
^] MEMBRANE DO PROBE
I RESIDUAL CHLORINE
OTHER ANALYTICAL ANALYZERS
I GAS MONITORS
] SAMPLING SYSTEMS
UNSATISFACTORY
FAIR
SATISFACTORY
Figure 2. Performance summary of measuring devices in wastewater- treatment facilities
600
-------
1972-3
IMO. OF CASES
10
15
20
25
30
35
LIQUID LEVEL CONTROL
LIQUID FLOWRATE CONTROL
SLUDGE PUMPING
AIR FLOWRATE
CHEMICAL ADDITION
RESIDUAL CHLORINE
DISSOLVED OXYGEN
PH
TURBIDITY
AUTOMATIC SCUM REMOVAL
AUTOMATIC DATA ACQUISITION
SUPERVISORY COMPUTERS
DIRECT PROCESS CONTROL BY DIGITAL COMPUTER
UNSATISFACTORY
FAIR
SATISFACTORY
Figure 3. Summary of automatic control experiences in wastewater- treatment facilities
601
-------
period. In spite of this increase, the
performance of the plant did improve. The
effluent BOD decreased from a geometric
mean of 11.1 ppm, obtained during manual
operation, to a mean of 3.9 ppm for auto-
matic operation. Figure 4 shows the
effluent BOD data plotted on logarithmic
probability paper to obtain a frequency
distribution of measurements. The slope of
the lines reflects the degree of reliabil-
ity. For example, in Figure 4 the reduced
slope of the automatic control line indi-
cates that automation will result in
tighter control of effluent BOD.
Further analysis indicated that the
sludge characteristics may also have been
affected by automatic DO control. The
frequency distribution of the sludge
volume index (SVI) is shown in Figure 5.
The arithmetic mean for the SVI with manual
control was 332. This was reduced to 86
with automatic control. The difference in
the slopes of the two lines is more marked
in this case (Figure 5) indicating a greater
advantage for automatic control in main-
taining a consistent product.
At Palo Alto the computer calculated
the DO setpoints using data obtained from
DO probes and then alerted the operator to
make the required change. In contrast
during the manual operation, the operator
monitored the DO twice per shift and then
made the appropriate corrections. When
the semi-automatic operation was compared
to manual operation (Figure 6), a 13%
performance improvement as measured by
effluent TOG and an 11% reduction in air
use was observed. The latter calculates
to a $5,380 savings per year for a 25 mgd
plant. When a cumulative frequency plot is
made of manual vs. DO control, the slopes of
the lines were equal indicating that the
reliability of both systems was similar.
This is understandable since the final
control implementation was carried out by
the same operators.
The other control strategies that
were evaluated at Palo Alto concentrated on
regulation of food-to-microorganism ratio
(F/M). Several techniques such as TOG, COD
and oxygen uptake were considered for
measuring the food. However, suitable
automatic TOG and COD analyzers were not
available for on-line control during the
Palo Alto experiments. Therefore, only two
F/M control strategies could be evaluated.
These were a) feedback respirometry control
using an on-line respirometer, and b) DO/
RAS control. In both cases the DO was con-
trolled as described previously and since
the results were similar only DO/RAS con-
trol loop will be described.
For DO/RAS control, the rate of air
demand was assumed to be proportional to
the BOD input and the return sludge was
adjusted to maintain the desired F/M ratio.
In other words, the entire aeration tank
was used as a respirometer to set the
return sludge flow.
In all these evaluations, the system
was allowed about 30 days to stabilize, and
then, three days of intensive sampling was
carried out. Figure 7 shows the BOD load-
ing (food uptake) that was measured every
two hours. Using the aeration tank as a
respirometer the food uptake was also
estimated and compared to the BOD loading.
Under manual operation, that is, maintain-
ing a constant RAS, the mixed liquor susp-
ended solids (MLSS) varied widely as shown
in Figure 8. When DO/RAS control is
employed, the MLSS becomes more constant
(Figure 9). However, when comparing
these results to those obtained when only
DO control was used the plant showed no
performance improvement in terms of
effluent quality or cost savings.
The results do indicate that DO control
is a valuable control loop that should
be explored further. The ease and sim-
plicity of installing and maintaining a
DO loop is more than compensated for by
the cost savings and performance improve-
ments. The case for F/M control however,
is not so conclusive. Because of fund
limitations, the evaluations at Palo Alto
were limited to about 30 days each. There
is some speculation that had more time
been allowed, especially for manual eval-
uations, more significant results could
have been obtained.
AUTOMATION OF PHYSICAL-CHEMICAL
TREATMENT SYSTEM
The basic physical-chemical process
sequence that was evaluated at Blue Plains
(4) is shown in Figure 10; it consists of
two-stage (high pH) lime precipitation
with intermediate recarbonation, dual-
media filtration, pH control with chlorine,
CO- stripping, breakpoint chlorination and
602
-------
100.0
90.0
80.0
70.0
60.0
'50.0
30.0
20.0
10.0
9.0
8.0
7.0
6.0
5.0
FIGURE 4 FREQUENCY DISTRIBUTION OF BOD IN THE EFFLUENT
99.99 99.9 99.8 99.5 99 98 95 90 80 70 60 50 40 30 20 10 5 21 0.5 0.2 0.1 0.05 0.01
2.0
I I
I I I
I
T T
I l
l
AUTOMATIC CONTROL
J I
J l
0.050.1 0.2 0.5 1
30 40 50 60 70
80
90
95
98 99 99.5 99.8 99.9
99.99
PERCENT OF OBSERVATIONS EQUAL TO OR LESS THAN STATED CLASS MEAN
-------
1000 i
900
800
700
600
500
400
300
FIGURE 5 FREQUENCY DISTRIBUTION OF SVI
99999.8 99.5 99 98
95 90
80 70 60 50 40 30 20
10
1 0.5 0.2 0.1 0.05 0.01
100
90
80
70
60
50
I I
I
I
I __
AUTOMATIC CONTROL
I
I
I
I
I
0.01 0.05 0.1 0.2 0.5 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99 99.5 99.8 99.9
PERCENT OF OBSERVATIONS EQUAL TO OR LESS THAN STATED CLASS MEAN
99.99
-------
ON
O
Ul
100
^ 80
tofl
" ••
i- S 40
20
CO
CJ
LU
GO
CO
I I I
0.2 1 5 10 20 30 40 50 60 70 80 90 95 99 99.8
CUMULATIVE FREQUENCY, %
FIGURE 6. DRY SEASON TESTS: SECONDARY EFFLUENT SUSPENDED SOLIDS
CONCENTRATION VS. LOG NORMAL FREQUENCY DISTRIBUTION
-------
40,000
30,000
20,000
o\
o
10,000
0
6
12 18
SUNDAY
2/10/74
o
6
0
6
12 18
MONDAY
2/11/74
DATE-TIME OF DAY
FIGURE 7 . AIR/RAS CONTROLLER: ACTUAL AND ESTIMATED FOOD UPTAKE
12 18
TUESDAY
2/12/74
o
-------
20 -
2000
O^
O
16
12
RAS
1500
MLSS
' \
'
V
1000
500
00
oo
6 12 18
SUNDAY
11/25/73
6 12 18
MONDAY
11/26/73
6 12 18
TUESDAY
11/27/73
DATE-TIME OF DAY
FIGURE 8 MANUAL TEST II: MLSS AND RAS VS. TIME
-------
CD
O
oo
CD
OO
20
16
12
MLSS
2,000
1,500 _
toJO
1,000
500
oo
6 12 18
SUNDAY
2/19/74
0 6 12 18 0
MONDAY
2/11/74
DATE-TIME OF DAY
FIGURE 9, AIR/RAS CONTROLLER: MLSS AND RAS VS. TIME
6 12 11
TUESDAY
2/12/74
-------
LIME SLURRY
-i H
LTU
LIME SLUDGE
PRODUCT
CARBON
ADSORPTION
C02-
r
FeCL3
LTTJ
LIT]
BASE
BREAKPOINT
CHLORINATION
CL2
U
LIME SLUDGE
L
J L
J
DUAL-MEDIA
FILTRATION
FIGURE 10
PHYSICAL CHEMICAL TREATMENT
TWO-STAGE CHEMICAL CLARIFICATION
WITH INTERMEDIATE RECARBONATION
609
-------
granular carbon adsorption. In the first
stage of the process, powdered lime, raw
wastewater, and recycled solids are
rapid-mixed, flocculated and settled to
remove bicarbonate, phosphate and
magnesium. The pH of the clarified
effluent is reduced from 11.5 to 9.5 in a
recarbonation tank. The effluent from the
second stage clarifier flows by gravity
through dual-media filters consisting of
coal and sand. After filtration, chlorine
is added in a static mixer to reduce the
pH to 6-7. Carbon dioxide is air stripped
from the filter effluent to reduce the
alkali required for the breakpoint
reaction. Breakpoint is achieved by add-
ing chlorine and alkali to the wastewater
ahead of a second static mixer and con-
tact tank. The base is added to control
the pH and prevent formation of undesir-
able end products such as nitrate and
nitrogen trichloride. Soluble residual
organics are removed from the wastewater
with two-stage downflow carbon columns
using a contact time of 40 minutes. A
high quality effluent is produced by this
treatment sequence. Typical water quality
includes 5 mg/1 of BOD, 15 mg/1 of COD,
0.15 mg/1 of P and 2.6 mg/1 of N (3).
Lime Clarification
A dry lime feeder maintains a constant-
concentration lime slurry which is cir-
culated through a head tank above the
primary reaction zone of the clarifier.
An electro-pneumatic valve meters the slurry
into the reaction zone on demand signals
from the lime-feed controller. The four
alternative strategies studied for lime-
feed control were 1) conductivity-ratio,
2) flow-proportional, 3) pH plus flow-
proportional, and 4) alkalinity plus flow-
proportional.
Figure 11 schematically represents the
basic components used in the four alter-
native control schemes. The conductivity-
ratio control scheme involves the measure-
ment of conductivity in the primary
reaction zone and in the influent waste-
water. The ratio of these conductivity
measurements generates a control signal
(C) for the lime-feed valve. For flow-
proportional control, the influent flow
rate is measured, and this signal (properly
modulated at MT and PS) is transmitted
directly to the control valve. For pH plus
flow-proportional control, the pH is
measured in the primary reaction zone, and
this signal is used to adjust the signal
generated from the flow-proportional loop.
For alkalinity plus flow-proportional
control, a sample is pumped from the
clarified zone of the clarifier through a
porous rock filter to an automatic titrator.
The resulting alkalinity signal is trans-
mitted to the multiplying transmitter in a
flow-proportioning control system for final
adjustment of lime addition.
The results of a seven-day test run
are shown in Table 1.
TABLE 1. PERCENTAGE DEVIATION FROM TARGET
DURING SEVEN-DAY TEST RUN
Control Scheme
Ranges of Deviation
from Target Alkalinity, %
Conductivity-ratio + 16 to -20
Flow-proportional + 15 to -15
pH plus flow-proportional + 10 to -10*
Proportional + 10 to -15t
Alkalinity plus flow-
proportional +7.5 to -7.5
*lst 2 days
tEntire 7-day test period.
Conductivity-ratio control was found to
be the least accurate control system, but it
would be a good backup control system since
it is dependable and the equipment requires
little maintenance. The flow-proportional
control system was very sensitive to any
change in lime-slurry concentration and was
very much dependent on the accuracy of the
flow measurement device. After seven days
of operation, the pH electrodes were coated
with a calcium carbonate scale which was
approximately 1/16-inch thick. This
coating was removed in 2% hydrochloric acid,
and the electrode regained its initial res-
ponse characteristics. By scheduling
electrode cleaning every 2 days, pH control
will work satisfactorily. Placement of the
pH probe in a separate rapid-mix tank
reduces the maintenance requirements as-
sociated with placement in the primary
reaction zone of a single-unit clarifi-
cation system.
While alkalinity plus flow-proportional
control produced the closest alkalinity
control of all the systems studied, the
610
-------
LEGEND:
T = Reference Transducer
MT = Multiplying Transducer
C = Controller
SC = Signal Conditioner
AD = Measuring Transducer
(Analytical Device)
PS = Pulse Transmitter
influent
REQUIRED COMPONENTS FOR CONTROL SCHEMES
TYPE OF CONTROL
CONDUCTIVITY RATIO
FLOW-PROPORTIONAL
pH PLUS FLOW-PROPORTIONAL
ALKALINITY PLUS FLOW-PROPORTIONAL
FIGURE 11
LIME FEED CONTROL SCHEMES
COMPONENT
T AD C
T MT PS
AD SC C MT
T MT AD PS
PS
-------
equipment malfunctioned repeatedly be-
cause of filter clogging. The inability
to filter high solids concentrations
efficiently required relocation of the
sample point from the reaction zone to
the clarified zone. This resulted in a
two-hour lag in the response time which
caused large swings in process effluent
quality when the lime-slurry concentration
changed. Until the solids handling problem
for alkalinity plus flow-proportional
control is solved, the recommended control
system is pH plus flow-proportional, with
conductivity-ratio control as a backup.
The solids wasting control loops for
the first and second stage clarifiers are
simple feedforward systems where periodic
pulses, proportional to flow, produce a
discharge. The discharge from this tank
is controlled by a level switch sensing the
fixed volume.
The control loop for the Fed, feed in
the recarbonation tank is a feedforward
flow-proportional system which changes the
duty cycle of the dosing pump.
The carbon dioxide dosing control sys-
tem is the same pH plus flow-proportional
control system used for the lime addition
control. The chemical dose is controlled
by a feedforward signal proportional to
flow and a feedback signal generated by
pH error.
Filtration
Operation of the dual-media gravity
filters was controlled with four, alterna-
tive, backwash initiation and control
schemes. Alarm schemes used to initiate
backwash had time-delay circuits to prevent
accidental or momentary events from
triggering the backwash cycle prematurely.
The four models used were 1) headless,
2) high-level (influent level), 3) pro-
grammed time-interval, and 4) manual. The
headless sensor initiates the backwash
cycle when the available head decreases to
a preset minimum valve (H.L. = 9 ft FLO).
When the level tends to change, the high-
level indicator opens an effluent control
valve so that a constant level is main-
tained. When the control valve is 100%
open, backwash is initiated. The pro-
grammed time-interval controller will
initiate backwash at the expiration of a
preselected number of operating hours.
The operator may over-ride any of the above
controls at any time with the manual mode.
The effluent from clarification was
distributed equally to the operating
filters by a mechanical splitter box. As a
filter was isolated for backwash, the flow
to that filter was redistributed to the
remaining operating filters. If the head-
loss alarm was used and if the filter
backwash occurred at peak flow rates, the
redistribution caused the already stressed
operating filters to be overstressed. The
final result was a chain reaction result-
ing in the need to backwash all available
filters in a relatively short period of
time which increased the requirements for
backwash-water pumps and storage capacity.
The programmed time-interval controller
was used to schedule filter backwashing at
different hours during periods of low flow;
this reduced backwash-water pumping and
storage requirements, and it eliminated
overstressing of the system. The headloss
indicator was then used as a backup alarm
to prevent flooding when system upsets
caused increased solids loading and short-
er filter runs than the programmed time
interval. The high-level alarm was
connected to an audio-visual alarm and was
used to indicate equipment failure. This
system has provided peak operating
efficiency at the lowest possible operating
cost.
Breakpoint Chlorination
The control scheme developed to con-
trol the breakpoint-chlorination process is
shown schematically in Figure 12. The
chlorine dosage-control loop employs a
feedforward signal proportional to the mass
of influent ammonia and a feedback signal
based on the free residual chlorine con-
centration error. The feedforward signal
is derived from the concentration of
ammonia in the influent, the influent
flow rate, and a preselected weight ratio
of chlorine to ammonia. If digital con-
trol of the system were practiced, this
feedforward signal would be adjusted by the
amount of chlorine used for pH control
during prechlorination. The control loop
for alkali addition (NaOH) is derived from
a feedforward signal based on the chlorine
dosage used and a feedback signal based
on the pH error. The on-stream analysis
of ammonia by a chlorimetric analyzer,
612
-------
influent
effluent
FT = Flow Transducer
RT = Ratio Transmitter
CCV = Chlorine Control Valve
pHC = pH Controller
pHT = pH Transducer
FIGURE 12
BREAK POINT CHLORINATION CONTROL
AT = Ammonia Transmitter
BPC = Break point controller
pH CV = pH Control Valve
SC = Signal Conditioner
CAT = Chlorine Ammonia
Transmitter
-------
both before and after breakpoint chlorin-
ation, has been accurate and dependable.
Free residual chlorine is also continu-
ously measured by a colorimetric analyzer.
Preliminary operating experience has been
favorable. Breakpoint chlorination reduces
operating problems with the carbon adsorp-
tion system by reducing biological slime
growths. The carbon adsorption process is
a good backup system for the breakpoint
chlorination process because of the de-
chlorination potential.
Carbon Adsorption
The carbon adsorption process pre-
sented control problems very similar to the
filtration system; however, the carbon ad-
sorption process was only semi-automated.
A level-controller regulated the flow
through the system, while an automatic
pressure-controller on the discharge side
of the carbon-column feed pump maintained
a constant pressure at the inlet to the
first carbon column. There were five
carbon columns interconnected in series by
headers and automatic valves to allow any
number of columns to be operated in se-
quence and any column to be the lead
column. Column sequencing and backwash
initiation were determined by an operator.
The lead column is backwashed daily in
the raw wastewater-treatment applications.
Direct Digital Control
An IBM Systems/7 computer was in-
stalled at the EPA Blue Plains Pilot Plant
to provide total systems control for the
independent physical-chemical treatment
sequence (5). The process-control com-
puter also performed a data-acquisition
function. Plant data from approximately
100 wastewater-process sensors were
collected, converted into engineering units
and stored for later analysis and eval-
uation of the systems performance.
Alarm modes were also included to
alert the operator of plant conditions that
require his attention and correction.
Examples are out-of-range alarms for such
parameters as pH and chemical doses to the
wastewater, as well as equipment-failure
alarms for such items as sludge-blowdown
equipment and pneumatic pumps.
Direct digital computer control is
being used more frequently in the larger
wastewater treatment facilities where the
economies realized in data acquisition,
reporting, preventive maintenance sched-
uling, load programming and improved per-
formance can offset the additional costs of
specialized manpower and the capital costs
of the initial hardware and backup system.
The capability to control individual unit
processes and indeed complete physical-
chemical treatment systems is rapidly be-
coming a reality.
RESEARCH NEEDS AND PROBLEM AREAS
To initiate a coordinated attack on
instrumentation and automation problems in
this field, a workshop entitled Research
Needs for Automation of Wastewater Treat-
ment Systems (6) was held in Clemson,
South Carolina in September 1974. This
workshop, sponsored by the EPA in cooper-
ation with Clemson University, provided an
opportunity for workers in this area to
discuss their research problems and needs.
The workshop found that the general
problem areas were the lack of: adequate
field experience, quantitative understand-
ing of wastewater systems, and required
sensors. Or to put it another way, the
problems are a lack of sensors and of fun-
damental knowledge about the treatment
processes. These problems were stated in
almost every session. To resolve these
problems, the needed research should in-
clude demonstrations of automated process
control, development of mathematical
models and algorithms, and evaluation of
sensors. The workshop also indicated a
need for an information clearinghouse, in-
cluding the international exchange of data;
and projected a new philosophy of waste-
water renovation as opposed to processing
wastewater to minimum quality requirements.
The cost-effective application of instru-
mentation and automation to wastewater
management systems will be a key to imple-
menting this philosophy. One immediate
outgrowth of the workshop was the establish-
ment of an EPA Advisory Committee on
Instrumentation and Automation for Waste-
water Management. The functions of this
advisory committee will be to:
614
-------
o serve as focal point for questions
concerning instrumentation and auto-
mation of wastewater management
systems within the United States,
and provide liaison with similar
groups in other nations
o facilitate the exchange of research
information in this area
o identify and characterize the tech-
nology required for instrumentation
and automation of wastewater manage-
ment systems
o assist the EPA in defining short-
and long-range research development
and demonstration programs
The roster of this advisory committee
consists of four EPA members and eight non-
EPA members. The latter represent state
and local governments, the academic
community, equipment manufacturers and pro-
fessional societies. The communication
resulting from such a widely represented
group is desirable because it establishes
a link between the user community, the
researcher and enforcement agencies.
This provides for the opportunity for each
of these groups to rapidly communicate
goals, problem areas and solutions with
one another.
REFERENCES
1. Molvar, A.J., et al., "Instrumentation
and Automation Experiences in Waste-
water Treatment Facilities." EPA
report being prepared for
publication.
2. Roesler, J.F., "Plant Performance Using
Dissolved Oxygen Control." Jour.
Environ. Eng. Div., 100, 1069 (1974).
3. Petersack, J.F. and Smith, R.G.,
"Advanced Automatic Control
Strageties for the Activated Sludge
Treatment Process." EPA-670/2-75-039
(May 1975).
4. Convery, J.J., et al., "Automation and
Control of Physical-Chemical Treat-
ment for Municipal Wastewater."
Applications of New Concepts of
Physical-Chemical Wastewater Treat-
ment, Sept. 18-22, 1972. Pergamon
Press, Inc. USA (1972).
Bishop, D.F., et al., "Computer Control
of a Chemical Clarification Waste
Treatment Pilot Plant." Presented
at the First International Meeting
Pollution: Engineering to Scientific
Solutions, Tel Aviv, Israel (June 12-
17, 1972).
Buhr, H.O., et al., Ed. "Research Needs
for Automation of Wastewater Treat-
ment Systems." Proceedings of a
Workshop held at Clemson, S.C.
September 23-24, 1974 (June 1975).
615
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RESEARCH REQUIRED TO ESTABLISH CONFIDENCE
IN THE POTABLE REUSE OF WASTEWATER
J.N. English, K.D. Linstedt, and E.R. Bennett
J.N. English, Sanitary Engineer, Wastewater
Research Division, Municipal Environmental Research
Laboratory, EPA, Cincinnati 45268; and K. D. Linstedt
and E. R. Bennett Associate Professors of Sanitary
Engineering at the University of Colorado
Boulder, Colorado 80302
ABSTRACT
A Municipal Research Needs Workshop, sponsored by the Environmental Protection
Agency (EPA), the Water Pollution Control Federation (WPCF), and the American Water Works
Association (AWWA), was held at the University of Colorado, Boulder, Colorado, in March
1975 to identify priorities for research that would provide scientific knowledge and
technology to prove the feasibility and practicability of reusing wastewater.s for potable
purposes. Ninety-two select persons concerned with municipal wastewater reuse in the
United States and abroad discussed and identified a long term research program involving;
treatment technology; treatment reliability and quality control; health effects associated
with organic, inorganic, and biological pollutants; and the socio-economic aspects of
potable reuse.
BACKGROUND
Sound management of water resources
must include consideration of the potential
use of properly treated wastewaters as an
alternate means of meeting future water
demands. Consumptive water use data
indicate that the lower Colorado River
region uses more water than its available
natural supply, and the Great Basin and
Rio Grande regions use 60 percent or more
of their average supplies (1). Large,
economically important regions of the
Nation already are, or will be using water
beyond the capacity of the available nat-
ural water resources. Steadily increasing
municipal and industrial water require-
ments in these areas, combined with
expanding irrigation activities, could
place severe strains upon limited water
resources. At the same time, many areas
are facing the growing problems of water
quality deterioration.
Groundwater in many areas is being
mined or used at rates exceeding recharge
capability. The present economy of these
areas is based upon the foundation of a
temporary and dwindling water resource.
In major groundwater-using areas, such as
Lond Island and Southern California,
substitute supplies can be obtained only
at relatively high cost. Where water
development costs and legal constraints
are making sources of raw water difficult
to acquire, wastewater reuse is an attrac-
tive alternative water source. In addi-
tion, reuse is an effective method of
dealing with water pollution by preventing
degradation of water quality.
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. The
Safe Drinking Water Act of 1974 also con-
tains mandates of importance with regard
to renovation and recycling of wastewaters.
In particular, Section 1444 authorizes a
development and demonstration program to:
(1) investigate and demonstrate health
616
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implications involved in the reclamation,
recycling, and reuse of wastewaters for
drinking; and (2) demonstrate processes
and methods for the preparation of safe
and acceptable drinking water from waste-
waters. 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 sup-
plementation of domestic water supplies.
Advanced wastewater treatment systems
developed primarily for pollution control
are available for removing pollutants to
very low levels. As a result of this
technology, and the need for additional
sources of water to meet present and
future requirements, renovated wastewater
is being considered in planning for over-
all water resources utilization in many
areas of the country. The treatment tech-
nology capability can be identified for
reuse applications such as agricultural,
recreational, and industrial where quality
requirements have been defined. The State
of California has already established
water quality standards for wastewater
used for agricultural and recreational
purposes (2). Since there are public
health questions in this country concern-
ing the degree and reliability of treat-
ment for potable reuse, the necessary
treatment technology is less well defined
for this use than for other types of
reuses.
Because of the limited experience
with direct or overt potable reuse of
renovated wastewater there are no stand-
ards to apply to such waters. The U.S.
Public Health Service (USPHS) Drinking
Water Standards of 1962, and the Environ-
mental Protection Agency (EPA) Proposed
Interim Primary Drinking Water Standards
apply to water sources that are as free
as possible from pollution. The concern
among many in the water field over the
uncontrollable source and characteristics
of wastewater has resulted in the recom-
mendation that renovated wastewater should
meet stringent standards in addition to
those written for unpolluted sources.
This concern would appear to be reasonable,
but should not be restricted to waste-
water since many surface water supplies
do not qualify as "unpolluted."
Health effects research relating to
wastewater reuse has not paralleled the
developments in wastewater treatment tech-
nology. The quality of present conven-
tional water supplies has only been
questioned rather recently relative to the
trace contaminants. Health effects studies
are presently underway on approved sources
of potable water. However, much remains
to be done since many problems, such as the
presence of organic materials and their
potential health hazards in drinking waters,
have not been solved. This needed research
will be applicable to wastewater reuse
since the production of water from surface
supplies that contain a significant portion
of effluents is analogous to the direct
recovery of water from wastewater.
In addition, research to determine the
economic, social, and political aspects of
potable reuse has not kept pace with treat-
ment technology development. The EPA has
only recently identified needed information
in this area, and this has come about as a
result of the potential availability of
highly treated wastewaters that are "too
good to throw away." These waters have
attracted the attention of those agencies
in water-short areas that are responsible
for maintaining adequate supplies of
drinking water.
RESEARCH NEEDS WORKSHOP
The Water Pollution Control Federation
(WPCF) and the American Water Works Assoc-
iation (AWWA) issued a joint resolution
that urged the Federal Government to sup-
port a massive research effort to develop
needed technology for the potable reuse of
wastewater. These organizations under-
scored the "lack of adequate scientific
information about possible acute and long-
term effects on man's health from such
reuse," and noted that "essential fail-safe
technology to permit such direct reuse has
not yet been demonstrated." The resolution
recognized 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 the full protection of the public
health."
The EPA Office of Research and Devel-
opment (OR&D), through its Municipal
Pollution Control Division, has devoted
effort for a number of years to the devel-
opment of wastewater treatment processes
capable of producing high quality effluents
617
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suitable for a range of reuse or recycling
applications. More recently the OR&D
Health Effects and Socio-Economic Research
Programs have initiated research related
to potential health problems and the
social-economic impact of reusing waste-
water.
Because of legislative mandates and
the need to include practical applications
of wastewater reuse in the management of
water resources, EPA has intensified its
efforts to identify research needs as a
first step in establishing a more viable
wastewater reuse program. To implement a
multi-disciplined research effort a method
was needed for identifying research prior-
ities and providing EPA with direction for
conducting the municipal wastewater
potable reuse research program. The work-
shop method was selected as the best
approach to defining and establishing
priorities for potable reuse research.
Ninety-two persons concerned with waste-
water reuse, from this country and abroad,
were brought together to discuss and
identify research gaps in the areas of
health effects, treatment technology, and
the socio-economic considerations of
potable reuse.
The Workshop was jointly sponsored
by the Environmental Protection Agency
(EPA), the Water Pollution Control Feder-
ation (WPCF), and the American Water Works
Association (AWWA), and was held at the
University of Colorado at Boulder,
Colorado on March 17-20, 1975.
The Workshop was three days in length
and was designed for persons involved in
the use, conduct, direction, or specifi-
cation of research in the wastewater ren-
ovation and reuse field. WPCF and AWWA,
and selected representatives of federal,
state, municipal, industrial, academic,
and consulting organizations participated.
In addition to presentations on specific
reuse situations that included both native
and foreign experience, papers were
presented on 1) potential health hazards
of using wastewater for domestic purposes,
2) the status of existing technology that
can be used to properly treat wastewater
for reuse, and 3) the socio-economic
aspects of reuse. The presentations
established the state-of-the-art, or
"where we are now."
The evening of the first day and the
entire second day were devoted to separate
workshop groups each dealing with one of
the following specific topics related to
potable reuse:
° Wastewater Treatment
° Treatment Reliability and Quality
Control
0 Health Effects Associated with
Inorganic Pollutants
0 Health Effects Associated with
Organic Pollutants
° Health Effects Associated with
Biological Pollutants
0 Socio-Economic Aspects
Workshop participants were divided about
equally between these groups according to
their interest and experience. Each Work-
shop group had a prior designated chairman
and vice chairman to guide the group dis-
cussions and summarize the problems iden-
tified and the research needed to solve
these problems. The results of each
group's efforts were presented to the
total Workshop attendees on the third day
for further discussion and multi-disci-
plinary comments.
IDENTIFIED RESEARCH
The research needs associated with
the potable reuse of municipal wastewater
as identified by the six individual Work-
shop groups are presented separately as
follows:
1. Treatment - Characterization of
the effectiveness of alternate wastewater
treatment systems for the removal of
organics, trace metals, nitrogen, bacteria,
viruses, parasites, and suspended material
was considered to be the highest priority
research need. The four treatment trains
shown in Figure 1 were identified as
having potential for reliably producing
potable quality water from raw (primarily
domestic) wastewater. A need was iden-
tified to evaluate these systems for
energy requirements, costs, by-product
production, overall reliability, and
removal of the pollutants previously
mentioned. It was estimated that the
intensive characterization period would
require at least three years, plus any
further time needed for evaluation of
618
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CI2
1. RAW
1
WASTE
f
LIME PRIMARY
TREATMENT
I -co2
PHYSICAL CHEMICAL
NITROGEN REMOVAL
'
1
CARBON
ADSORPTION
T
MIXED MEDIA
FILTRATION
T
CHEMICAL
OXIDATION
EFFLUENT
CI2
II. RAW
1
WASTE
PRIMARY
TREATMENT
t
AERATION BASIN
1
SECONDARY
SEDIMENTATION
If
LIME
TREATMENT
| -C02
MIXED MEDIA
FILTRATION
i
1
PHYSICAL CHEMICAL
N REMOVAL
1
CARBON
ADSORPTION
REVERSE
OSMOSIS
CHEMICAL
OXIDATION
III. RAW WASTE
*
PRIMARY
TREATMENT
*
COMBINED CARBON AND
NITROGEN REMOVAL
*
SECONDARY
SEDIMENTATION
T
LIME
TREATMENT
CH3OH *- 1 -< C02
CARBON
ADSORPTION
'
r "•* CI2
CARBON
ADSORPTION
t
MIXED MEDIA
FILTRATION
t
CHEMICAL
OXIDATION
IV. RAW
1
WASTE
f
LIME TREATMENT OR
ACTIVATED SLUDGE
1
NITRIFICATION
i
SEDIMENTATION
1 -« CH3OH
DENITRIFICATION
i
SEDIMENTATION
CARBON
ADSORPTION
*
MIXED MEDIA
FILTRATION
i
CHEMICAL
OXIDATION
VARIATIONS
(many possible)
RESIN SORPTION
FOLLOWING CARBON OR
REVERSE OSMOSIS
TWO STAGE LIME
FOR SOFTENING
ION EXCHANGE
ULTRAFILTRATION
FOLLOWING FILTRATION
DISTILLATION
INCLUDED IN EACH
EFFLUENT STORAGE
DISINFECTION
MULTIPOINT COAGULANT
^f ADDITION
CI2
KEY
CI2 = Chlorine for residual
ammonia removal
C02 = Carbon dioxide
for recarbonation
CH3OH = Methanol for
denitrification
EFFLUENT
EFFLUENT
EFFLUENT
FIGURE 1. VARIOUS POTABLE WATER TREATMENT PROCESS TRAINS
-------
health effects. It was established that
each system should be demonstrated on at
least a 0.5 mgd (1890 cu.m./day) scale to
establish performance credibility, and
that the systems should be applied to
municipal wastewaters, domestic waste-
waters, and polluted river water.
System I is an independent physical-
chemical process. System II is a second-
ary-tertiary process. System III is
similar to System II except that the bulk
of the nitrogen is removed in the initial
one-step biological treatment stage.
System IV is an integrated chemical-
biological treatment system. Rough costs
were estimated to be (1975 dollars) :
$3,000,000 construction cost per system.
Analytical and operation costs (excluding
health effects) $800,000/yr. per system.
Disinfection is a mandatory require-
ment for potable wastewater reuse to
insure protection of the public from
infection. This requires the disinfection
process to have a high degree of control
and reliability with essentially no
allowance for short term process failure.
Four subcategories required to better
direct the research in disinfection
include: 1) examination of the by-pro-
ducts of all disinfection processes,
2) delineation of processes that can pro-
duce safe residual levels of disinfectants,
and 3) identification of the best points
for application of disinfectants in the
treatment system.
Present technology for organic
removal results in product waters contain-
ing 1 to 2 mg/1 of total organic carbon.
Although it has not been detemined that
there is a health hazard at this concen-
tration, a need was identified to find
processes to reduce the materials to lower
levels. Potential methods that should be
studied are chemical oxidation; resins;
membranes; and volatile stripping. New
methods and ideas for removing trace
organics should be solicited from appro-
priate sources.
The identification and validation
of indicators of system performance was
identified as being necessary to permit
monitoring without developing a burden-
some analytical load. This will be
required for reliable and cost-effective
operation. An example of the indicators
would be the use of turbidity and chlorine
residual measurements as indicators of
virus inactivation.
It was concluded that nitrogen
removal will be required, but that cur-
rently available physical-chemical and
biological nitrogen removal processes will
need review because each has disadvantages.
Modifications of these processes should be
investigated to reduce their overall costs.
Although processes are available for
removing many of the trace metals of
concern from wastewater, selenates, arse-
nates, chromates, and molybdates are not
well removed by most of the common AWT
processes. Further study of potential
removal processes is required. Demineral-
ization for reducing salinity is a tech-
nique that has a beneficial effect on the
removal of these ions, but the various
demineralization processes need evaluation
and improvement to reduce costs and
energy requirements.
Two essential factors in reuse -
quantity and quality - are impacted by
storage. Storage may occur both inplant
(recycle streams), and before or after the
renovation facility. The main concern is
finding the least costly method of providing
the storage since the benefits of flow
equalization and product protection are
clearly evident.
Demonstration of methods for stabili-
zation, recovery, and disposal of
residuals is needed to insure the avail-
ability of adequate and economically
viable control options for the accumulated
residuals emanating from reuse treatment
processes. This problem area is not
unique to potable reuse, but it was iden-
tified as an important factor for eventual
implementation of specific reuse treatment
methods.
2. Treatment Reliability and Quality
Control - A need was identified to define
drinking water standards that can be
applied with confidence to potable waters
derived from polluted sources. The type
of treatment systems and their reliability
requirements will depend on the standards
set for the produce water. Fail-safe
reliability must be defined and the
factors and procedures must be established
which will assure that the product water
620
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from a reuse system will be withheld from
use if all quality criteria are not met.
The overall performance of a reuse
treatment system may be affected by:
1) the time-dependent changes in the mass
flow of some influent constitutents; 2)
the presence or absence of unknown indus-
trial constitutents; 3) the recycling of
side streams; and 4) inplant chemical
additions which may result in chemical
reaction by-products. Therefore, infor-
mation is needed on effluent variability
and process reliability as they are
affected by influent variability, the
reliability of systems treating only
domestic wastes vs. those treating com-
bined domestic and industrial wastes, and
the effects of recycle streams.
Some contaminants in domestic waste-
water have been or will be identified as
having an acute or chronic health effect
when present in varying concentrations
in reused wastewater. The cost of remov-
ing these contaminants in reuse systems
will vary depending on the variability
and reliability of removal required.
Effective design and operation of reuse
systems dictates that a level of "risk"
be established that identifies the per-
missible variation in the removal
efficiency of contaminants, and balances
this with the cost of complete contaminant
removal.
Once specific reuse systems are
chosen, they should be evaluated to
determine if there is a need for new types
of equipment not now available. The
needed reliability of such equipment
should be determined and design specifi-
cations developed. As new products or
equipment become available, their impact
on potable reuse systems should be
assessed and the information disseminated
to the water industry. The rapid expan-
sion of technology will bring new
pollutants into the domestic and indus-
trial wastewater streams that require
continual updating of removal technology.
The key to product quality control
in a reuse system lies in the availability
of suitable monitoring systems. It is
imperative that a few specific indicator
parameters be identified and that auto-
mated monitoring equipment be developed
so that the parameters can be correlated
with the contaminants that may be health
hazards.
Potable reuse systems are likely to
be very complex. Step by step operation
and control strategies with contingency
action plans are needed in the event of
process failures. Research is required to
determine the frequency of failure of key
pieces of equipment in various unit
processes. Preventive maintenance pro-
cedures for both process equipment and
instrumentation are needed to extend the
life and increase the reliability of major
reuse equipment. Increased operator
capability and effective management are
necessary to efficiently and reliably
operate the complex treatment systems.
Studies are needed to define the minimum
plant size that is amenable to reliable
operation, and to determine the staffing
and organizational requirements to insure
consistent operation.
Before successful reliability design
can be achieved it is necessary to deter-
mine the allowable contaminant variability
as well as monitoring and sampling fre-
quency to insure adequate process control
for providing the reliable removal of
specific contaminants.
3. Health Effects/Inorganics -
Research on this topic is intimately
related to other environmental health
research, especially to that relevant to
drinking water criteria. This research
is also related to ongoing studies on
categorical diseases such as cancer and
heart disease, and to geographical
gradients in morbidity and mortality
rates.
There is a need to compile data on
the occurrence of inorganic materials in
water and wastewater in those geographic
areas where potable reuse is most likely
to occur first. Multi-elemental analyt-
ical techniques such as spark source mass
spectrometry, x-ray, fluorescence emission,
and neutron activation should be used.
Research is needed to perfect sample
preparation techniques in order to
increase the sensitivity, accuracy, and
precision in monitoring.
Organometallic compounds and metal
chelates are widely used in industry and
have a high probability of occurrence
and build-up in wastewaters. Little is
known of their health effects, and ident-
ification is difficult. Examples include
621
-------
alkyl and aromatic amines, and dicar-
boxylic acid compounds that form complexes
with metal cations.
The mere presence of an element or
compound in water need not imply that
there is any appreciable uptake. The
material may be in an insoluble form,
complexed, or chelated. Both animal and
human studies, along with improved physi-
cal-chemical characterization are needed
to determine the uptake fractions for
various forms of inorganic constituents
in water. Little is known of the role of
particulate matter and its influence on
uptake.
Populations consuming water of vary-
ing qualities should be examined from an
epidemiological standpoint to determine
whether specific contaminants represent
a potential health effect. Body burden
estimates can be based on medical research
from samples of scalp hair, nails, blood,
urine, subcutaneous fat, and deciduous
teeth. Body burden changes can be
detected more readily and much earlier
than manifest toxicity. Hence, a greater
level of health protection is implied
than if one awaited more serious effects.
Where cities are known to have differences
in water constituents, autopsy, placental
tissue, or surgical specimens may show
that different water constituents lead to
different concentrations of these same
constituents in target organs. It may be
possible to relate high levels of storage
to morbidity and mortality from various
causes.
In-vitro bacterial and cell culture
systems should be used for the study of
contaminants in water as: 1) primary
toxicity screens; 2) indicator systems
for determining active fractions in
various fractionation schemes and refrac-
tionation of the active portions, and
3) systems for study of the interactions
of chemicals for toxicity including
mutagenesis and carcinogensis.
Conventional animal toxicity studies
use relatively healthy normal animals,
yet human health effects of greatest
concern involve effects on infants,
women during pregnancy, and on those with
cardiovascular diseases. There are no well
established relationships between results
on healthy animals and those with impair-
ment. Accordingly, studies are needed of
selected types of animal systems to
obtain toxicity data relevant to high
risk human groups.
Behavioral toxicology has been shown
to be a useful test system for effects of
nitrites in rats. It has been shown to be
a very sensitive indicator of the effects
of certain compounds and is probably the
only way alterations in cerebral function
by toxic agents can be approached in
animal studies.
The amount of inorganic materials in
water does not necessarily relate to the
amount ingested, since a high proportion
of the liquid intake is from food and
beverages. Therefore, it is necessary for
each substance and class of substances to
estimate the population dose based on
usual food, beverage, and water ingestion.
Present epidemiological data relat-
ing death rates to components of drinking
water, including components resulting
from indirect or covert reuse of waste-
water, are confused and uncertain. There
is a need to obtain information on the
chemical content of drinking water in
metropolitan areas that exhibit a wide
range of death rates. Studies should be
made on the degree of association and
correlation between these data and the
age-sex-race-specific death and disease
rates, particularly for age groups between
35 and 74 years, for the specific areas
where available water data on sodium,
hardness, IDS, and trace metals exists.
Comparisons of areas using polluted and
clean water sources should have priorities,
There is a need to coordinate an epidemi-
ology assessment strategy to insure that
kinds and amounts of pollution and
possible health reactions are measured
uniformly. A small interdisciplinary
group with international support could be
convened to develop and design such a
strategy.
A city planning overt reuse of waste-
water will require many different types
of data, accurately collected and analyzed,
to determine whether reuse has an adverse
effect. Properly designed registries of
the incidence and prevalence of chronic
disease are efficient basic tools for
this purpose. The registry should include
data for two or more years before overt
622
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reuse, and for several years after reuse,
on chronic as well as acute episodes of
disease.
Associations of cadmium ingestion and
hypertension have been reported as well as
an association of hardness with low rates
of cardiovascular disease. The substances
responsible for this association have not
been clearly determined. Some of the
contaminants in reused wastewater may be
relevant to this association. Comparison
studies in like communities with different
degrees of covert reuse, or in communities
changing their water supply, can assist in
resolving these questions.
Rates of the incidence of "serious"
chronic disease vary from place to place.
Areas exhibiting marked differences in
chronic disease rates should be utilized
in determining the possible relationships
between incidence and concentration of
water constituents indigenous to each area.
Hospital discharge reports and death
certificates can be used to document
incidence of "serious1' disease.
4. Health Effects/Organics - Many
existing water supplies contain appreci-
able quantities of organic compounds.
These compounds may present a health
hazard if they are carried into potable
water supplies. Efforts are underway to
evaluate the toxicity of organic compounds
in water supplies where various degrees of
covert reuse occur. There is a need to
carry out short-term toxicological studies
on actual wastewater effluents (and con-
centrates of them) produced by advanced
waste treatment facilities designed for
overt potable reuse. Appropriate standard
techniques for concentrating refractory
organics that maintain the integrity of
the chemical components are a prerequisite
for these studies. Only chemicals iden-
tified from highly toxic fractions and
suspected of being chronically toxic
should be subjected to longer term testing.
These long term tests should include con-
sideration of the synergistic potential.
The practice of disinfection of water
for biological safety has brought with it
the creation of many new and potentially
toxic chemicals. Attention must be paid
to the reaction products resulting from
the different means of water disinfection,
such as the use of ozone, chlorine, and
UV light. Residual compounds such as
epoxides, aldehydes, and acids need
careful assessment.
Research on analytical methodology
designed to identify specific organic
pollutants, some of which are hazardous
to health, should be coordinated with
ongoing work in program areas of municipal
wastewater, industrial wastes, and drink-
ing water research. Techniques of
isolation, concentration, identification,
and quantification of organics should be
improved. Quantitative recovery methods
that do not allow introduction of arti-
facts as well as more studies on the
identification of nonvolatile, higher
molecular weight compounds are required.
The recent development of in-vitro
bacterial systems serve as sensitive
indicators of a candidate compound's
carcinogenic/mutagenic potential and
should be given serious consideration as
a screening tool early in the evaluation
of the health hazards of a compound or
water concentrate.
Utilization of short term in-vitro
mammalian procedures, such as the use of
animal or human liver tissue may provide
guidelines in the early screening evalu-
ation of organics. The metabolism of the
organics found in reused wastewater should
be studied to determine the best possible
models for toxicity testing.
Relatively simple and rapid gross
chemical or biological methods should be
developed that give good correlation with
the presence of compounds of health
significance. These methods must be able
to be used for routine monitoring of
potable water supplies to give assurance
that organics in the water do not con-
stitute a hazard to health. Analyses such
as total organic carbon (TOC), chemical
oxygen demand (COD), carbon chloroform
extract (CCE), volatile organic analyses
(VOA), mutagenic microbial assay, and
other potential gross analyses should be
compared with measured concentrations of
compounds found in water that are
determined to be potentially hazardous,
so that safe levels based on the gross
techniques can be established.
The interaction of pollutants should
be assessed. The importance of synergis-
tic effects of, for instance, specific
623
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chlorinated hydrocarbons with alcohols
and their oxidation products (aldehydes
and ketones) in amplifying toxicity
effects requires additional study.
In order to evaluate the potential
health hazards of reclaimed waters for
potable reuse, there is a primary need to
establish the kinds of organics which are
present and their concentrations. Such
background information will aid in the
formulation of toxicological and other
health hazard assessment plans related to
organics in drinking water. In addition,
these studies will be very useful in
comparing characteristics of organics in
reclaimed wastewaters with present drink-
ing water supplies.
Epidemiologic surveys of population
groups exposed to heavily polluted surface
waters are needed. The aim is to deter-
mine whether there are any detrimental
health effects resulting from such long
term exposure. The studies would include
testing of the body fluids and tissues for
the accumulation of compounds of potential
toxicologic importance. The sources of
organic pollutants in water are diverse
and include municipal wastewater, airborne
wastes, industrial and agricultural
wastes, and other products of commerce.
For certain pollutants, studies should be
undertaken to evaluate the relative hazard
of these compounds in water as compared
to their hazard from other sources.
Because of the diversified problems
involved in evaluating the health effects
of potable reuse, there is a need to
develop a viable and visible program
coordinator within EPA to assess the
potability of reused wastewater. Also,
there is a requirement for a scientific
definition of what constitutes "potable
quality." When this has been done, the
requirement for health effects testing of
water from both overt and covert reuse
situations will be clarified.
An assessment of hazards to operators
of wastewater renovation and reuse
facilities should be conducted. Besides
the hazards of exposure of workers to
chemicals related to the chlorination
process, hazards of exposure to ozone or
UV light should be considered.
There is a need to coordinate re-
search efforts in the direction of
standardizing methods for evaluating the
health effects of organics in reused
waters to be used for potable purposes.
Coordination of research should be under-
taken on an international level with such
agencies as WHO and the agencies of
specific countries directly involved in
such endeavors. The output from the
various international programs should be
integrated and disseminated by periodic
newsletters on a regular basis to all
participants. The newsletters would
address research in progress or planned,
tabulation of specific organic compounds
identified in waters, and any toxicity
data and supporting information.
5. Health Effects/Biological - One
of the primary public health considera-
tions for the potable reuse of wastewater
is the prevention of communicable diseases
by virus and other pathogenic micro-
organisms. The disinfection process is a
major means by which virus are rendered
non-infective in any reuse system. In
order to achieve disinfection the inacti-
vating agent must reach the virus.
Methods are needed for the determina-
tion of the extent to which kill effi-
ciency is affected by adsorption of the
organism to, or entrapment in, solids for
waters of low turbidity levels (0-1 JTU).
Procedures for detecting viruses on or in
solids and the means of exposing adsorbed
virus to the disinfectant should be
developed. Hepatitis A virus is the major
enteric virus involved in water borne
disease outbreaks, and the development
of methods for its detection and identifi-
cation are of the highest importance.
Methods are also needed for the detection,
isolation, and assay of other viruses
which are excreted from the human enteric
tract and which are of public health
importance in renovated waters. Infor-
mation is needed on the mechanisms of
inactivation of viruses by disinfection
and adsorption. Knowledge of the exact
mechanisms would lead to modifications of
existing processes to improve their
efficiency. The fate of viruses in the
treatment system will become predictable
when disinfection and adsorption mech-
anisms are better understood.
There is an unquestioned need for the
development of a rapid and simple testing
method that would indicate the presence of
viruses and other pathogenic organisms in
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renovated waters. A comparative methods
study and evaluation of various cell
culture systems should be undertaken with
respect to their ability to detect
viruses. The best systems should be stan-
dardized so that a uniform method would
become available to all workers, and would
also permit a comparison of laboratory
findings between laboratories. Research
should be supported to provide a stand-
ardization of cell systems that would
afford a reproducible method for recover-
ing a test seed of virus and for assaying
infectivity titers.
Data are required on the occurrence,
survival, and fate of viral and bacterial
pathogens in all types of treatment plant
sludges, and on the interaction between
pathogens in the sludges and soils of
varying composition.
There is a need to prepare a state-
of-the-art document concerned with the
removal and inactivation of microbial
pathogens by pH extremes and by chemical
coagulation processes. Such information
is necessary for a rational approach to
the development and standardization of
optimum treatment conditions for the
removal and inactivation of microbial
pathogens.
Information is needed on the minimal
amount of ingested virus that will produce
infection. This information would provide
the basis for establishing viral standards
for renovated waters.
A study should be undertaken to
determine the extent to which bacteria
that colonize activated carbon and other
solid contact systems release toxic and
pyrogenic materials. The released toxins
and pyrogens should be identified and
their potential health hazards determined.
There is a need to conduct in-depth
surveillance and monitoring for the
presence and concentration of viruses in
effluents from existing pilot and full-
scale wastewater reclamation plants which
employ treatment trains that are likely
to be used in future production of potable
water. Also, data are required on the
potential public health hazard of airborne
dissemination of pathogenic bacteria and
virus. The information would aid in the
public decisions related to plant-siting.
6. Socio-Economic Aspects - Attempts
to institute potable reuse have not been
frequent enough to develop a clear picture
of social reaction. Resistance is expected
unless clearly defined standards are estab-
lished that have the support of the public
health officials at all government levels.
A national survey, as well as local
investigations of areas of potable reuse
need and feasibility should be implemented.
This includes the identification of the
extent to which the U.S. population is
presently being supplied former wastewater
as part of their raw water supply. A
careful analysis of the amount of waste-
water in present drinking water sources
should be useful in demonstrating the
possible degree of pollution of existing
water supplies. Public education on cur-
rent indirect potable reuse is needed.
Methods of educating the public, most of
whom are using some wastewater in their
domestic supply, are required so that they
can be informed of this in such a way that
they will understand and accept it.
Recycling of municipal wastewater has
the potential of impacting the quantities
available for upstream and downstream water
users. Individual state water laws must
be interpreted, modified, or both, to
accomodate the implementation of reuse.
Identification of significant legal pre-
cedents which could constrain the imple-
mentation of such reuse is needed.
Numerous regulatory entities exist
which may have jurisdiction over various
water-consuming activities within a given
area. Identification of such agencies and
delineation of their respective responsi-
bilities would alert water purveyors to
standards, regulations, and legislation
that could constrain potable reuse. The
environmental assessment could lead to
considerable litigation if the appropriate
standards, regulations, and legislation are
not adequately addressed.
Basic economic data are needed on the
value of a certain level of water quality
to the consumer. That is, how much money
is the average household consumer willing
to pay for a higher level of water quality?
Planning for reuse would be significantly
advanced if data were available on the
perceived vaiue of a higher quality water
over another quality. This is particularly
625
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germane to decisions to implement recy-
cling now, wait until technology is
farther advanced, or to develop more
expensive conventional supplies.
A study should be conducted on the
effects of various methods of encourage-
ment that can be exerted by funding and
regulatory agencies on separate water
supply and wastewater treatment entities
to get them to coordinate their efforts in
water management programs that include
reuse.
Efforts should be made to determine
and forecast the relative importance of
the types of sociological, institutional,
and economic problems that will be faced
by cities pioneering potable wastewater
reuse. This would include a determination
under varying sets of circumstances, of
the proportion of reclaimed water the
public will accept in their domestic water
supply. There is considerable evidence
that public attitudes currently oppose
drinking reused wastewater. This
attitude persists despite objective
evidence that "accidental" or indirect
reuse, equal in contamination to direct
reuse, is common. The problem faced by a
pioneering city is that public attention
by tourists, convention-goers, and other
non-residents may lead to a negative
community reaction.
A number of cities are proceeding to
develop water reuse technology on the
assumption that potable reuse will become
feasible in another 10 to 15 years. The
problem which could arise is that public
health concerns may not be overcome when
scheduled. The possiblity exists that a
legal injunction may be granted, on the
request of health experts or even environ-
mental groups, which bars implementation
of the project. For this reason, assess-
ment of the social and economic impacts
of unexpected delays in scheduled reuse
become necessary.
History shows that as innovations
increasingly become adopted, resistance to
adoption fades. Data is needed on the
likelihood and extent to which socio-
logical, institutional, and economic
problems faced by cities practicing
potable use of wastewater will diminish,
as more and more cities adopt this
practice.
In view of the fact that our present
drinking water supplies are often more
economical than potable reuse water, it is
imperative from an economic standpoint that
existing supplies be conserved to the
greatest extent possible within the pre-
sent "life style" of the community. Due
to the "unlimited supply" attitude that
has existed, the American public has
unconsciously become very wasteful of
water. A survey directed to a review and
compilation of the various water conser-
vation programs that have been instituted
by water agencies is needed to disseminate
the information and expand the practice of
conservation of resources. This would
lead to the development of a viable and
operable water conservation program for
use by utilities.
SUMMARY
It is anticipated that a program
undertaking the research previously des-
cribed will require a minimum of 10 to 15
years of intensive work to develop
sufficient information to clearly define
meaningful standards that can be applied
with confidence to potable waters derived
from a polluted source. These standards
will have to be based on realistic public
health considerations and have the support
of public health officials at all govern-
ment levels.
The goals of a direct or overt pota-
ble reuse program are similar to those of
the present EPA Health Effects and Water
Supply programs which have recently
identified organic materials having poten-
tial health hazards in many of our Nation's
drinking waters. Some of these supplies
contain appreciable quantities of waste-
waters, and their use for domestic purposes
can be classified as an indirect or covert
form of potable reuse.
There was a general consensus of the
Workshop attendees that the research
identified must be addressed by both water
supply and wastewater organizations. Even
if direct reuse is not implemented, all
the same questions which have been raised
must be answered, and the technology must
be developed to remove potential health
hazard constituents present in our water
supplies.
Any program of the magnitude required
to alleviate the health concerns of both
626
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overt and covert potable reuse is not a
local or even a national undertaking.
International coordination is necessary
since other nations such as South Africa,
Israel, and some in the European community
are facing deteriorating and unreliable
water supplies, and are actively research-
ing the problems involved with covert and
overt potable reuse.
The research identified at the
Workshop will be used to lay out a long
range approach which will utilize the
results from the ongoing EPA Wastewater,
Health Effects, and Water Supply Programs.
By clearly defining a strategy for potable
reuse the results from these programs can
be used as "stepping stones" for a future
potable reuse research program.
REFERENCES
1. "Water Policies for the Future,"
National Water Commission, Washington,
D.C., (June 1973).
2. "Statewide Standards for the Safe
Direct Use of Reclaimed Wastewater for
Irrigation and Recreational Impound-
ments," State of California Department
of Public Health, Berkeley, CA (May
1968).
627
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AGENDA
WASHINGTON, D. C.
WATERSIDE MALL - ROOM 3305
Tuesday, October 28
9:00 am F. Green - Welcome
J. T. Rhett - Conference Opening
Dr. T. Kubo - Response
Dr. W. K. Talley - Remarks, Office of Research
and Development
R. A. Canham - Greetings from Water Pollution
Control Federation
J. T. Rhett - Introduction of Delegates and
Confirmation of Agenda
9:30 am W. S. Groszyk - Planning for Urban Runoff Control
Under a Comprehensive Water
Quality Management System
10:15 am Break
10:30 am R. B. Schaffer - Control of Water Pollution
Through Issuance of Discharge
Permits - Implementation of
P.L. 92-500
11:15 am E. P. Hall - The EPA Pretreatment Program for
Industrial Wastes
12:00 noon Luncheon - Hosted by the Water Pollution
Control Federation
1:30 pm C. C. Taylor - Municipal Sewer Utility Financing
Under P.L. 92-500
2:15 pm J. T. Rhett - A Perspective on Municipal Pollution
Control - The Construction Grants
Program and P.L. 92-500
3:00 pm Break
3:15 pm J. G. Moore, Jr. - Commission Charge - Tentative Staff
Issues and Findings National Commission
on Water Quality
4:00 pm J. T. Rhett - Closing and Announcements
628
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PLANNING FOR URBAN RUNOFF CONTROL UNDER COMPREHENSIVE
WATER QUALITY MANAGEMENT SYSTEM
Walter S. Groszyk
Deputy Director, Water Planning Division
Environmental Protection Agency
East Tower, Room 815 - WH-554
401 M Street, S.W.
Washington, D.C. 20460
ABSTRACT
I
This paper summarizes the approach being developed by the U. S. Environmental
Protection Agency for the abatement of urban storm runoff. The approach features the
development, at the local or regional level, of specific management practices to
control runoff. These practices emphasize non-capital intensive methods of minimizing
the pollutant loading of runoff and are formulated through a comprehensive areawide
planning effort that assesses the dimensions of the runoff problem, the water quality
effects, and abatement needs.
TEXT
The United States Environmental Pro-
tection Agency through the States and
cities conducted a survey of the estimated
construction costs to abate storm sewer
pollution. This survey of needs amounted
to nearly $250 billion in current dollars.
While the number does not generally reflect
any engineering plans or detailed surveys,
its rough magnitude is staggering and
beyond the digestive capacity of the Fed-
eral budget. There is simply no foreseeable
way that the Federal Government would be
able to finance a construction program of
this size for this problem. It exceeds by
tenfold the total program of landing a man
on the moon, and is nearly ten times the
total annual contract construction value in
the U.S. gross national product for 1973.
As an additional perspective, the estimated
costs, in this same Needs Survey, for con-
structing treatment plants, interceptor and
collection sewers, and controlling combined
sewers totalled approximately $100 billion,
with the total need becoming nearly $350
billion.
Areawide Planning
Under the Federal Water Pollution Con-
trol Act, an areawide planning program is
to be conducted in urban-industrial areas
with significant water quality problems.
This planning program has just begun, and
at the present time planning is under way in
149 areas at a cost of $163 million. This
planning covers many of the largest cities
of the United States, including New York,
Philadelphia, Chicago, and Detroit. These
plans will eventually cover the entire
United States. Presently, about 45% of
the population and 11% of the land area
of the United States are covered by area-
wide planning.
Areawide planning is also called 208
planning, after the number of the section
of the Federal Water Pollution Control Act
which authorizes it. Areawide planning is
quite unique for three reasons. It is
expected to be the largest planning pro-
gram ever funded by the Federal Government;
all the financing for the program comes
from the Federal Government; and the law
requires that the plans be implemented.
Areawide planning conducted for a local
area is a comprehensive plan. The plan
covers both point and nonpoint sources of
pollution. It includes: initial facilities
planning for municipal sewage treatment
works; an identification of industrial, pol-
lution control requirements; and the
629
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identification of practicable methods and
procedures for the control of nonpoint
sources of pollution, including runoff from
agricultural, silvicultural, mining, and
construction activities.
The planning effort is conducted at
the city and county level, and is under the
direction of the chief elected officials of
local government within the planning area.
This will assure that plan development
reflects the views of the government
officials who will operationally implement
the plan. The initial plan is to be comp-
leted not later than three years after the
planning agency has been approved by EPA.
At the time of completion, EPA is required
to approve the designation of the manage-
ment agencies who will carry out the plan.
The planning agency continues to function
and develops revisions to the plan as they
are required.
This stress on locally originated
planning conducted under the direction of
locally elected officials reflects an
appreciation that levels of abatement more
stringent than those required by nationally
applicable effluent guidelines for industry
or uniform secondary treatment for munici-
palities can often best be addressed by
examining the specific pollution problems
in that area which remain after national
levels of control are applied; assessing
the institutional and financial capabili-
ties that exist or can be developed to
abate the sources of this remaining pollu-
tion; and then making the tradeoff's
between alternative control methods to
develop the most effective and reasonable
way of reaching the water quality
objectives.
Best Management Practices (BMP's)
The Environmental Protection Agency,
to assist planning agencies in making these
tradeoff's, is developing informational
guidelines outlining different methods and
procedures that can be used to abate non-
point source pollution including urban
runoff. These informational guidelines are
called Best Management Practices or BMP's.
A BMP is not an "end of the pipe" techno-
logical control level, but rather is a way
of doing business. It is directed to the
activity being conducted; as an example, it
may indicate that sediment runoff from a
farmer's field can be reduced by changing
the manner in which the farmer plows the
field. BMP's are being developed for all
categories of nonpoint source pollution,
including urban runoff.
BMP's for a particular category
present an array of alternative practices
with varying economic costs and efficiency
rates. The practices often identify cli-
matological or topographical suitability.
From this inventory of BMP's we expect the
planning agencies to select those practices
which most fit the abatement needs of their
area. The planning agency is not required
to use any of the BMP's but may develop an
equivalent BMP on its own. While Best
Management Practices are generally con-
cerned with non-capital intensive methods
of control, they are not exclusively so.
A planning agency may also, after analysis,
determine that the most effective and
economic way to achieve water quality goals
for that area is through the construction
of facilities and structures.
BMP's and Urban Runoff
Our present perception is that it is
neither necessary nor possible to treat all
storm waters. A receiving water is subject
to stresses caused in part by various
natural and uncontrollable occurrences.
Many streams experience difficulty during
the low flow and high temperature period
of later summer. Wet weather conditions
represent yet another period of stress.
The true extent of the storm water
problem is largely unknown and the lack of
any extensive historical studies or con-
cern makes it difficult to characterize.
Considering the area and route that
urban runoff takes, it is not surprising
that this runoff contains substantial
amounts of organic material, inorganic
material, inorganic solids, nutrients,
heavy metals and micro-organisms. The
impacts from this runoff are often
increased oxygen demand, high turbidity,
and increased eutrophication rates. Addi-
tionally, the impact of heavy metals on the
aquatic environment has to be considered.
The total pollutant load in storm-
water, during storm runoff periods, can be
greater than the pollutant load discharged
from municipal treatment plants during dry
weather. This could preclude meeting water
quality standards regardless of the degrees
or types of treatment afforded dry weather
630
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wastewater flows.
Related problems resulting from
unregulated, or poorly regulated, runoff
are accelerated erosion of land area and
stream banks, sedimentation of channels,
increased flooding, increased potential for
public health problems and deterioration of
aesthetic quality.
Assessing the impact of stormwater run-
off is not easy. Part of the difficulty
lies in the variability of stormwater run-
off. The quantity and quality of storm
overflows, for example, can vary with
respect to storm characteristics, antecedent
conditions, time, location, degree of urban-
ization and other factors. This variability,
the differing problems in new and expanding
urban areas compared with existing areas,
and the scarcity of information concerning
stormwater impact on receiving waters pose
challenges to the formulation and admin-
istration of an effective management program.
Some of the examples of these varying
factors are that: loading rates are lowest
in commerical areas; BOD 5 and COD concentra-
tions are lowest in residential and heavy
industrial areas, while the COD concentra-
tion is highest in commerical areas; cadmium
concentrations are relatively uniform across
all areas; chromium, nickel, and copper are
lowest in residential areas, with lead con-
centrations lowest in heavy industry areas;
and finally, and surprisingly, there is no
significant difference between land use
category and fecal coliform count.
From the analysis of the specific prob-
lem parameters with respect to water quality
and with a correlation as to the likely land
use areas and the sources of the problem,
the planning agency can then analyze which
BMP's it might apply to control the problem.
BMP's within an urban/suburban area
include source regulation, collection system
control, treatment, and an integrated
approach using all three. Source control is
defined as those measures for preventing or
reducing stormwater pollution that utilize
management techniques (e.g., good house-
keeping methods) and stormwater detention
within the urban drainage basin before
runoff enters the sewerage system.
Collection system control includes all
alternatives pertaining to collection
system management, such as use of sewers as
detention facilities. Treatment, including
storage, is another technique. The term
storage refers to stormwater being retained
for the purpose of treatment as opposed to
storage used in source control to attenuate
the rate of runoff. Flow attenuation is
concerned directly with runoff as it moves
over the surface of the urban area; i.e.,
the initial collection system. Flow attenu-
ation, in an hydrologic sense, means to
increase the time of concentration and
decrease the magnitude of the peak runoff.
In terms of water quality this means that
runoff velocities are reduced and less pol-
lutants are entrained. Also, less erosion
results because reduced runoff velocity
reduces the erosion force. Moreover, large
volumes of water are not allowed to rapidly
accumulate at constrictions, but flow at
reduced rates over a longer period of time,
thus reducing the possibility of localized
flooding. An integrated approach might
include source control to help reduce pol-
lutant loads and runoff rates; collection
system control (sewerage) to reduce infil-
tration and to attenuate the runoff; and
treatment as a final stop where required
to meet water quality objectives.
The management goals become:
1. Prevention and/or reduction of
pollution.
2. Detention or retention of runoff.
3. Treatment of runoff.
An additional goal that should not be
overlooked is reuse of stormwater runoff.
Reuse of stormwater places urban runoff in
the resources category. It should be con-
sidered in those areas that can benefit from
groundwater recharge and supplemental sup-
plies for both potable and nonpotable use.
The goal of the planning approach is
to provide sufficient pollutant reduction
to meet water quality objectives at a
minimum cost. BMP's for urban runoff
should stress source and collection system
management, and reuse where applicable.
Treatment should be resorted to only when
all other lower cost methods have failed to
provide sufficient pollutant reduction.
Urban runoff management should
initially emphasize the new urban areas.
These new areas include land that is in the
process of becoming urbanized. These are
areas that allow for the greatest degree of
631
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flexibility of approach in addressing the
long-term problems. At a minimum, urban
runoff pollution must be contained to pre-
sent problems. Once contained, then
emphasis can shift to problems associated
with existing areas. Of course, for this
approach to be effective, complete area
coverage is required and the approach
should be implemented as appropriate
throughout the entire planning area.
For a BMP to be considered as a best
management practice, it must meet certain
general and specific criteria. Factors
that need to be addressed within a BMP
include, but are not limited to, the
following.
A BMP must be compatible with the
hydrology and meteorology of the planning
area. The frequency, intensity, duration,
and surface area extent of precipitation
must be addressed; also, infiltration
rates, depression storage, and runoff
rates. Groundwater must be considered in
relation to recharge areas and levels, and
effect on stream channels fed from ground-
water.
Runoff from snowmelt in some areas of
the country (for example, in parts of the
West) produces the major portion of the
annual runoff. An important factor in
considering snowmelt is the temperature.
Other factors to be addressed are wind and
humidity.
Topography, of course, is a factor
that must be considered. A BMP must be
compatible with the slope, length of basin,
and type of surface cover of the planning
areas.
Geology is another factor to be
addressed. Soil types vary widely across
the country. A BMP must consider and be
compatible with this variable.
The specific examples of BMP's that
can be examined are to be considered as
being site-specific and are not to be con-
strued as being applicable nationwide.
Source Control
Some examples of source control are:
1. Street sweeping or control
through housekeeping.
2. Sewer flushing to reduce first
flush effects.
3. Detention basins.
4. Rooftop storage and parking
lot storage.
5. Porous paving, to increase
infiltration.
Collection System Control
Some examples of collection system
control are:
1. Use of existing sewerage as
detention facilities.
2. Use of swirl concentrators.
Treatment
Two examples which have been studied
and have been found feasible for storm-
water treatment are:
1. Micro-straining with air
floatation.
2. Contact stabilization.
Institutionally, we expect the
planning process will work in the follow-
ing manner.
The planning agency staff will assess
the magnitude and extent of the urban pol-
lution problems. These will be presented
to the public and any advisory groups to
ensure that a basic understanding of the
problems is shared by all.
The staff will then formulate water
quality goals based on protecting bene-
ficial uses of water. These will be
discussed with the public and will be
presented to the advisory committee. The
advisory committee overseeing the develop-
ment of the plan will select the approach
which best meets the goals.
Proposed criteria for controlling
urban runoff pollution will be prepared
by the staff in consultation with the
public. An inventory of alternative BMP's
which meet the proposed criteria will be
made.
632
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The staff will evaluate and make
initial selection of those BMP's which
meet the water quality objectives, and the
public and advisory group will decide which
of the BMP's are institutionally and
economically acceptable. Final selection
of the BMP's will be made then by the staff.
After the urban runoff problem has
been assessed, runoff reductions to help
meet target load allocations achieved by
the use of BMP's often need to be trans-
lated into ordinances or regulations.
Within EPA, we believe the use of the
areawide planning process together with the
systematized assessment of BMP's offers an
attractive alternative to total reliance
on capital facilities for control of urban
runoff. The planning process has just
begun, and we would like to report at a
future conference on the results from this
effort.
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CONTROL OF WATER POLLUTION THROUGH ISSUANCE OF
DISCHARGE PERMITS, IMPLEMENTATION OF P.L. 92-500
R. B, Schaffer
Director, Permits Division
Office of Enforcement
U.S. Environmental Protection Agency
Washington, D. C. 20460
OBJECTIVES OF THE NPDES PROGRAM
On October 18, 1972, the Amendments to
the Federal Water Pollution Control Act es-
tablished the National Pollutant Discharge
Elimination System (NPDES). With the enact-
ment of this new legislation Congress has
stated that it is the National goal that
the discharge of pollutants into navigable
waters be eliminated by 1985. As an interim
goal it is stated that there be attained by
July 1, 1983, water quality which provides
for the production and propagation of fish,
shellfish and wildlife and provides for the
recreation in and on the water.
Any permit issued under the National
Permit System will impose on a discharger
of pollutants from a point source certain
requirements designed to attain the goals
of the Act. Every discharger must make
application for a permit and in so doing,
provide the permitting authority with data
on the discharge. Each issued permit will
meet effluent limitations, water quality
standards, new source performance standards
for new plants, and toxic pollutant stand-
ards. Facilities discharging into a muni-
cipal waste treatment facility do not re-
quire a discharge permit, but the discharger
must comply with pretreatment standards
promulgated under the Act. Permits will
require the discharger to monitor the dis-
charge, to keep records of monitoring ac-
tivities and report periodically on what is
occurring with regard to the discharge.
THE EFFLUENT LIMITATIONS
The new Act provides for uniform ef-
fluent limitations for industrial categories
and achievement dates. Congress set two
interim dates of July 1, 1977 and July 1,
1983, by which different levels of treat-
ment are to be reached. It is a timetable
based on advances in technology.
For all discharges other than publicly
owned treatment works, not later than July 1,
1977, effluent limitations are to be achieved
which represent the application of the "Best
Practicable Control Technology Currently
Available." At the same time, all publicly
owned waste treatment facilities must uti-
lize "secondary treatment" and, if an indus-
trial discharger sends its waste through a
publicly owned treatment works, certain "pre-
treatment standards" must be met. An addi-
tional requirement is that by the July 1977
date, effluent limitations may be imposed so
that any state law will be met. Not later
than July 1, 1983, effluent requirements
must be met which represent the "Best Avail-
able Technology Economically Achieveable"
and, for publicly owned waste treatment
facilities, which represent the application
of the "Best Practicable Waste Treatment
Technology/' Any other applicable pretreat-
ment standards must also be attained by that
date. Special standards of toxic substances
must also be observed for both the 1977 and
1983 targets.
The target dates are 1977 and 1983;
they are the outside limits for compliance.
The Act envisions that in meeting effluent
limitations there will be stages of compli-
ance including attainment of levels of sub-
stantial improvement even before these dates.
Therefore, most permits will impose a
schedule of remedial measures. This sche-
dule will appear as a condition set out in
an NPDES permit.
The Agency has requested authority to
extend the 1977 date on a case-by-case basis
for publicly owned treatment works. However,
we do not feel it is necessary to extend the
date for other dischargers nor do we expect
the National Commission on Water Quality to
recommend it to Congress.
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BEST PRACTICABLE CONTROL TECHNOLOGY
AND BEST AVAILABLE TECHNOLOGY
The Act charges the Administrator with
the task for publishing regulations provid-
ing "Guidelines" for effluent limitations
for point sources after he has consulted
with the appropriate Federal and State
agencies and other interested persons. These
effluent limitations are the ones which
shall require the application of the Best
Practicable Technology by 1977, and Best
Available Technology Economically Achieve-
able for the 1983 target dates. Two things
will be identified in the regulations.
First, they will give meaning to the
terms "Best Practicable" and "Best Avail-
able" when applied to various categories
of industries. In defining "Best Practic-
able" and "Best Available" for a particular
category, such factors as the age of the
equipment and facilities involved, the pro-
cess employed, the engineering aspects of
the application of control techniques, pro-
cess changes, and non-water quality environ-
mental impact (including energy require-
ments) will be taken into account. In
assessing "Best Practicable Control, a
balancing test between total cost and ef-
fluent reduction benefits is to be made.
Cost is also a factor in determining "Best
Available." "Best Available" technology is
the highest degree of technology that has
been demonstrated as capable of being de-
signed for plant scale operation, so that
costs for this treatment may be much higher
than for treatment by "Best Practicable"
technology. Yet economic feasibility will
also be a factor in interpreting "Best
Available" treatment. Cost effectiveness
for either standard is to be confined to
consideration of classes or categories of
point sources and will not be applied to
an individual point source within a cate-
gory or class.
Second, having interpreted "Best Prac-
ticable" and "Best Available" guidelines
will be published which will determine what
"Effluent Limitations" are to be imposed on
dischargers. In these guidelines the degree
of effluent reduction attainable through the
application of the "Best Practicable Control"
and "Best Available Technology" in terms of
amounts of constituents per unit of produc-
tion. These guidelines can then be applied
in setting specific effluent limitations on
dischargers.
The Agency will promulgate these various
standards and guidelines for some 200 classes
and categories of dischargers.
TOXIC POLLUTANT EFFLUENT STANDARDS
The Act requires the establishment of
effluent standards or prohibitions controll-
ing toxic pollutants. Toxic pollutants are
defined as those pollutants, or combinations
of pollutants which, after discharge and
upon exposure to any organism either directly
or indirectly, will "on the basis of infor-
mation "available" cause death, disease, or
other abnormalities in the organism or its
offspring. The drafters of the Act had in
mine certain substances such as mercury,
beryllium, arsenic, cadmium pesticides, etc.
A list of toxic pollutants has been
proposed. Effluent standards for those
toxic pollutants listed will be published
later.
NEW SOURCE PERFORMANCE STANDARDS
Most new plants will be subject to
national standards for performance. EPA is
to publish a list of categories of sources
which must include 27 major types of indus-
tries and then issue regulations establish-
ing Federal standards of performance for
the new sources within such categories.
These standards are to assure that new sta-
tionary sources of water pollution are de-
signed, built, equipped, and operated to
minimize the discharge of pollutants. The
standards are to reflect the greatest degree
of effluent reduction which the Administra-
tor determines to be achievable through
application of the best available demon-
strated control technology, processes,
operating methods, or other alternatives.
"Best Available Demonstrated Technology" has
been described as those plant processes and
control technologies which, at the pilot
plant or semiworks level, have demonstrated
that both technologically and economically
they justify use in new production facili-
ties.
At the same time EPA promulgates new
performance standards, it is to provide
pretreatment standards for newly constructed
point sources discharging into public treat-
ment facilities.
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WATER QUALITY STANDARDS
The new Act does not ignore the concept
of water quality standards in 19.77 and 1983
achievements. Water quality standards which
were adopted and enforced under the old
Federal Water Pollution Control Act (FWPCA)
for interstate waters are continued in effect
and can be updated and the new ones are to
be established for intrastate water bodies
where not previously adopted by the States,
If water quality standards cannot be pro-
tected by the application of best practic-
able control technology for industries and
secondary treatment for municipal wastes
before 1977, then more stringent effluent
limitations are to be imposed which will
pro-tect water quality for public water
supplies, agricultural and industrial uses,
assure protection of a population of fish
and wildlife, and allow recreational activi-
ties.
EFFLUENT LIMITATIONS
The permit will contain one or more
sets of numerical limitations which must be
met by a date specified in an associated
compliance schedule. In general, the ef-
fluent limitations, with the exception of
pH, will be expressed in terms of total
weight (Ibs/day or kg/day). The effluent
limitations in the permit are described in
terms of daily average and daily maximum
values. The limitations expressed in the
permit are based on promulgated effluent
guidelines, interim guidance or water
quality standards if more stringent limits
are necessary to protect water quality. The
limitations or standards established by the
Agency are to be applied in a uniform manner
throughout the country. The standards are
minimum technological requirements to be
applied even though the receiving water may
not require that level of abatement to
achieve the desired water quality.
COMPLIANCE SCHEDULE
The compliance schedule will specify
when final effluent limits must be attained
and may also contain dates for achieving
certain plateaus such as development of
engineering reports, final plans, beginning
of construction, completion of construction
and the operation of facilities. Interim
dates and requirements are to be specified
in the permit as a means of monitoring
progress and minimizing slippage. Following
each interim date, the permitee must submit
a written notice of compliance or non-com-
pliance with the interim requirements. The
reports specified in the permit are very
important and should be submitted on time.
Failure to report, especially on construc-
tion progress or compliance, will result in
response from the Agency.
MONITORING AND REPORTING
The self-monitoring requirements con-
tained in the permit will be developed on an
individual basis with consideration given for
the type of treatment, the impact of the pro-
posed treatment facility on the receiving
water and the parameter to be measured. The
purpose of the monitoring program is to
establish that a treatment facility is con-
sistently meeting the effluent limitations
imposed in the permit. Data must be recorded
and retained on file by the permittee for at
least three years. The reporting frequency
of monitoring results will be specified in
the permit. A uniform reporting form has
been developed and will be provided to the
permittee. The self-monitoring may vary
from State to State as individual conditions
are developed to insure compliance with
State r equir ement s.
The permits are issued for fixed terms.
The maximum duration of a permit will be
five years. The majority of permits have
been written for that period since it will
involve commitment to a long term abatement
program. Permits may be written for a
shorter period, however, e.g., the State
may require it or the facility may cease
operation.
STATE CERTIFICATION
After drafting, a permit is forwarded
to the appropriate States for certification.
The State has the right to add additional
requirements in monitoring, compliance, and
additional or more stringent effluent limit-
ations. The Agency, upon receipt of certi-
fication requirements, will place these in
the permit. Any challenge to any State
certification requirements must be through
State administrative procedures.
636
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STATUS OF THE PROGRAM AS OF JUNE 30, 1975
EPA and 24 States which were delegated
the authority to issue NPDES permits had,
as of June 30, 1975, issued 20,091 Indus-
trial permits; 16,664 Municipal permits;
1,548 Agricultural permits; and 1,988 Fede-
ral Facility permits making a total of
40,291 permits issued. Approximately 1600
EPA issued permits have been challenged
through Administrative Processes. Of these,
400 have been resolved through discussions
between interested parties, e.g., govern-
ment, industry, and public interest groups.
We expect very few appeals to proceed
through this process and into our courts.
A study to determine the total amount
of certain pollutants that will be removed
from our Nation's waters due to the imple-
mentation of P.L. 92-500 and the industrial
portion of the permit program resulted in
an estimated reduction of approximately 12
million pounds per day of BOD and 28 million
pounds per day of suspended solids.
The continuation of our effort will
now shift into compliance monitoring to
assure that the terms and conditions of the
permits are met and the goals of the Act
achieved.
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THE EPA PRETREAIMENT PROGRAM FOR INDUSTRIAL WASTES
Ernst P. Hall
U.S.E.P.A.
401 M Street, S.W.,(WH5b2) Washington, DC
20460
ABSTRACT
The Federal Water Pollution Control Act Amendments of 1972 (PL 92-500) directs the
promulgation of Federal standards for pretreatment of industrial waste waters which are
introaucted into a publicly owned treatment works. These standards will require pretreat-
ment to control pollutants which would interfere with a pass through a treatment works.
Enforcement will be primarily at the local level with a Federal overview and presence.
Pretreatment of industrial wastes
before introduction into a publicaly
treatment works (POTW) has been discussed
by Mr. Sutfin at the second U.S./Japan
Conference. Since that presentation there
have been a number of refinements in our
thinking and approach to pretreatment.
This paper reflects the present status of
these refinements.
The Federal Water Pollution Control
Act Amendments of 1972, were designed by
Congress to achieve an important objective
to "restore and maintain the chemical,
physical, and biological integrity of the
Nation's waters." Primary emphasis for
attainment of this goal is placed upon
technology based regulations. Existing
industrial point sources which discharge
into navigable waters must achieve
limitations based on Best Practicable
Control Technology Currently Available
(BPT) by July 1, 1977 and Best Available
Technology Economically Achievable (BAT)
by July 1, 1983 in accordance with
sections 301(b) and 304(b). New sources
must comply with New Source Performance
Standards (NSP) based on Best Available
Demonstrated Control Technology (BDT)
under section 306. Publicly owned
treatment works (POTW) must meet
"secondary treatment" by 1977 and best
practicable waste treatment technology by
1983 in accordance with sections 301(b),
304(d) and 201 (gj(2)(A). Users of a POTW
also fall within the statutory scheme as
set out in section 301(b). Such sources
must comply with pretreatment standards
promulgated pursuant to section 307.
Limitations and standards applicable
to direct dischargers are established for
categories and subcategories of point
sources. This same categorization is
applied to pretreatment and pretreatment
standards, generaly, will
for each category or
industrial point source
general pretreatment
existing sources (40 CFR
be established
subcategory of
discharge. A
regulation for
128) was adopted
some two years ago and is now undergoing
revision, ihe revised regulation (40 CFR
4u3) is expected to provide a regulatory
basis for both existing and new sources.
The term "pretreatment" means the
application of physical, chemical and
biological processes to reduce the amount
of pollutants in or alter the nature of
the pollutant properties in a waste water
prior to discharging such waste water into
a publicly owned treatment works. Ihe
basic purpose of pretreatment is "to
prevent the discharge of any pollutant
through treatment works...which are
publicly owned, which pollutant interferes
with, passes through, or otherwise is
incompatible with such works." The intent
is to require treatment at the point of
discharge complementary to the treatment
performed by the POTW. Duplication of
638
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treatment is not the goal. Pretreatment
of pollutants which are not susceptible to
treatment in a POTW is absolutely critical
to the attainment of the overall objective
of the Act, both by protecting the POTW
from process upset or other interference,
and by preventing discharge of pollutants
which would pass through or otherwise be
incompatible with such works.
Pretreatment standards should allow
the maximum utilization of a POTW for the
treatment of industrial pollutants while
preventing the misuse of such works as a
pass-through device. The standards also
should protect the aquatic environment
from discharges of inadequately treated or
otherwise undesirable materials.
The primary technical strategy for
establishing pretreatment standards
consists of the following provisos: (1)
pretreatment standards should allow
materials to be discharged into a POiW
when such materials are similar, in all
material respects, to municipal sewage
which a "normal type" POTW is designed to
treat; (2) pretreatment standards should
prevent the discharge of materials of such
nature and quantity, including slug
discharges, that they would mechanically
or hydraulically impede the proper
functioning of a POiW; (3) pretreatment
standards should limit the discharge of
materials which, when released in
substantial concentrations or amounts,
reduce the biological effectiveness of the
POTW or achievement ot the POTW design
performance, but which are treated wnen
released in small or manageable amounts;
and (4) pretreatment standards should
require the removal, to the limits
dictated by technology, of other materials
which would pass through -- untreated or
inadequately treated -- or otherwise be
incompatible with a normal type POTW.
In addition to these provisos, it
appears to be administratively necessary
and technically desirable to establish a
volume cutoff or limit below which most
materials may be discharged into a POTW,
while requiring pretreatment standards for
larger flows and more hazardous materials.
This is intended to be accomplished by
defining, for the purpose of the
regulation, a major contributing industry
is a discharger who either (a) has a flow
of 50,000 gallons per day, or (b) has a
flow equal to or greater than 5% of the
capacity of the POiW. Any discharger
meeting either of these requirements would
be subject to all pretreatment standards
while a discharger not classified as a
major contributing industry by this
criteria may not be required to meet
specific numerical pretreatment standards.
The specific determination is to be made
in each subpart and for some particular
subparts it may be desirable to alter or
change the definition of a major contri-
buting industry in order more properly to
apply pretreatment standards, particularly
where use of the volume cut-off would not
provide adequate protection to the
environment.
The first proviso is clear in its
application and materials meeting this
proviso should be allowed to be introduced
into a POTW without pretreatment. uther
applications ot these provisos will oe
discussed in the following paragraphs.
I he control of influent pH is usually
adjusted adequately, particularly for
mildly acid wastes, by the alkalinity and
buffering capacity of normal municipal
waste waters. Additionally, if necessary,
treatment of pH can readily be
accomplished by chemical addition in a
POTW. However, highly acid wastes
characterized by materials having a pH
below five have the capability for
destroying the sewer pipes and sewaae
treatment facility itself because of their
ability to attack metal, concrete and
mortar joints. One particularly adverse
reaction from the corrosion of acid wastes
is to destroy the integrety of in concrete
sewers, thereby allowing the infiltration
of water during a rainy season. For this
reason, very low pH wastes -- below a pH
of 5.0 -- are included as prohibited
wastes even though pH is generally
considered to be adequately treated in a
POTW.
Heat is defined in the Act as a
pollutant. In most cases, heat in fairly
substantial quantities can be discharged
into a municipal sewage system along with
waste water without causing an upset or
other difficulty in operating the POTW.
As a matter of fact, some heat,
particularly in cold weather, may prove to
be beneficial, and may accelerate the
effectiveness of the treatment process.
However, the normal POTW includes
biological treatment systems whose
performance can be affected adversely if
an excess of heat is found in tne
treatment plant itself. This point of
damage to biological activity is generally
639
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considered to be 40%C (I04%F). Hence,
some safeguard is needed to prevent an
excess of heat being discharged to the
treatment plant while still allowing
lesser amounts of heat to be discharged to
and dissipated in a POTW.
Slug discharges which cause an upset
in the treatment process and a subsequent
loss of treatment effectiveness are
undesirable both for environmental and
treatment plant operational reasons.
Defining a slug discharge in quantative
terms is difficult. It' is commonly
recognized that the peak two hour flow
rate of normal municipal sewage is about
two times the ratio of the average daily
flow. This ratio holds for both hydraulic
loading and for oxygen demand (BOD)
loading. In order to establish a readily
definable discharge level at which an
industrial user may become liable for
causing a POTW upset, a slug discharge is
defined based on the normal maximum to
average ratio. However, the prohibited
waste section does not prohibit slug
discharges per se but only prohibits slug
discharges which cause a POTW upset.
Some materials are known to be treated
effectively in small concentrations in a
POTW but are not treated effectively
whenever the amount of such materials
exceeds the system's tolerance levels.
Regulation of these types of materials can
effectively allow the POTW to treat as
much of the pollutant as it reasonably
can, while preventing an excess of such
material from passing through untreated or
reducing the treatment effectiveness of
the PuTW. One such material currently
under review by the Agency is oil and
grease of a mineral origin. The Agency is
considering establishing a general
limitation setting forth a specific
concentration as a pretreatment standard
for this particular parameter and a
request for public comment on this
proposal has been published in the Federal
Register (40FR17/62). This general
limitation would be implemented in each
subpart regulation rather than in a
general regulation. Other materials such
as ammonia, phenol and cyanide may be
considered for limitation in the same
manner as oil and grease of a mineral
origin.
Materials may at times be introduced
into a POTW in industrial waste waters for
which no treatment effectiveness data tor
a normal type POTW are available or for
which the known data indicate that
treatment effectiveness in the POTW is
highly variable or inadequate. In such
cases, it is obvious that the POTW cannot
be depended upon to effectively and
consistently remove the pollutant in
question. Under these conditions the
Agency expects to consider the application
of BPT or NSP limitations as the
pretreatment standard for these specific
materials. Materials which may be
included in this category would include
metals such as copper, nickel, chromium,
zinc and arsenic, and selected organic
materiaIs.
Regulations under sections 301 and 306
generally have been established allowing
the discharge of a quantity or mass of
pollutant related to a unit of production
or other production vector. This basis
for limitation has the considerable
advantage of reducing the discharge of the
amount of pollutants to a finite quantity
while encourging conservation in the use
of water and the reduction in the
generation of waste water within a
manufacturing process or operation. I he
Agency believes that mass limitations best
fulfill the purposes of the Act. Mass
limitations based on similar
considerations appear to be the most sound
and effective mechanism for reducing the
amount of pollutants discharged to a POTW
whenever such pollutants would pass
through or otherwise be incompatible with
such works. I he Agency intends to use
this concept of limiting the mass of
pollutants discharged as the technical
basis tor the establishment of
pretreatment standards for many
pollutants.
The enforcement strategy, which the
Agency proposes to employ to achieve
pretreatment ot industrial wastes
envisions the application and enforcement
of these pretreatment standards by State
and local bodies including the POlW
receiving and treating the industrial
waste waters. It has been determined, that
many State and local authorities are not
yet anle to apply production related mass
limitations. Moreover, the Act does not
provide tor pretreatment permits analogous
to the NPDES permits of section 402. For
this reason, the Agency, at this time,
expects to promulgate pretreatment
standards which are oased on the discharge
of a specified quantity of pollutant,
related to a production vector (e.g., Ibs
640
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of pollutant per ton of product), but
wnich are stated as a concentration of
pollutant in the discharge from a
particular industrial process or unit
operation. It is anticipated that the
rationale for the derivative of the
pollutant concentration standards will be
described in detail in the preamble to
each pretreatment standard for an
industrial subcategory. It is also
anticipated that restrictions and
constraints against water use and dilution
may be included when appropriate for each
subpart. It is intended that such
pretreatment standards be applied at the
individual process unit. Additionally an
alternate procedure will be made
available, as is appropriate for each
subpart, so that mass limitation may be
applied if both the industrial user and
POTW operator desire.
The Agency believes that the use of
pollutant concentrations as a pretreatment
standard for those materials which may
pass through untreated, or are otherwise
incompatible with a POTW is an interim
measure made necessary by the practical
constraints of enforcement. At some
future revision of these pretreatment
standards, the Agency anticipates that the
concentration numbers will be abandoned
and the mass limitation will become the
sole pretreatment standard.
All of the pretreatment standards
being considered are intended to apply to
users of a "normal type" of publicly owned
treatment works which is basically
designed and intended to treat domestic
waste waters to achieve the secondary
treatment standards as established in 40
CFR 133 and as required by the Act. The
secondary treatment standard requires that
a sewage treatment plant, in addition to
controlling pH and fecal coliform, reduce
the amount of biochemical oxygen demand
(BOD5) to 85 percent or less of the
influent value or to 30 mg/1 in the
discharge, whichever is the more
stringent. A similar restriction is
applied to suspended solids.
There are a number of sewage treatment
systems, which when properly designed and
operated, meet these requirements on a
consistent basis. These include the
activated sludge system and its
modifications, trickling filters, and
stabilization lagoons or oxidation ponds.
There are a number of activated sludge
system modifications which incorporate
variations on the amount of sludge
recirculation, the amount of air or oxygen
supplied to the reaction chambers, the use
of pre- and post-chlorination, and the use
of sludge digestion, sludge combustion, or
land filling as mechanisms tor disposal of
the sludge generated. The retention time
of sewage in such systems generally is
short; it is nominally considered to be 6
hours while retention times as short as 3
or 4 hours are not uncommon. Trickling
filters are often used where the input
waste water is relatively constant and
where savings in power and operator
attention are needed. Stabilization
lagoons or oxidation ponds can be used
where the necessary land area is available
and where climatic and soil conditions are
such that the long retention times
required by such lagoons or ponds can be
achieved. "A normal type" POTW should not
have regular, substantial chemical
additive needs for the purpose of removing
materials other than BOD and TSS.
Existing publicly owned treatment
works rarely include processes such as
physical chemical treatment (wnich is only
now becoming a full scale reality in a few
areas) or special variants or combinations
of biological treatment units that are
primarily intended to address the special
needs of industrial waste water pollutants
rather than domestic waste or water
quality requirements.
Variations from the promulgated
pretreatment standards may be necessary in
certain circumstances to compensate for
factors not adequately considered in
establishing these standards. This has
been recognized in the establishment of
other industrial effluent limitations and
is equally applicable to pretreatment
standards. Two kinds of variants appear
to be appropriate depending on the
particular circumstance.
In the preparation of the development
document for each point source category
all of the information which the Agency
could collect concermna processes and
procedures related to the industry
subcategory was collected and analyzed.
It is possible, however, that certain
facts did not become available to the
Agency and could not be employed in
decisions related to the pollutants which
may be discharged from a particular
industry operation or would be related to
the treatability or impact which such
pollutants might have upon a POTW. For
641
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this reason, a variance clause is provided
which would allow the establishment of a
pretreatment standard, other than that
promulgated in the applicable subpart, in
those cases where it could be shown that
factors related to the industry category
fundamentally different from those
considered in the development document
these factors require the
of a different pretreatment
exist and that
establishment
standard.
An analogous situation may occur with
respect to factors related to the publicly
owned treatment works. A
is provided to allow
pretreatment standard to
for those cases where a
treatment works can
substantially different
type
which
variance clause
a different
be established
publicly owned
be shown to be
from the normal
of publicly owned treatment works on
pretreatment standards are being
based. Some of these types of
installations are known to exist or are in
the planning or design stage. However, at
this time it is difficult to establish a
separate regulation which would make an
allowance for different factors in such
publicly owned treatment works.
Although both EPA and the States will
play major roles in enforcing pretreatment
requirements, the Agency believes that
local governments will probably have to
play the most important role in any
successful enforcement program. Local
governments operate the POTWs, which are a
vital part of the overall effort to clean
up the nation's waterways, and so are
sensitive to and directly affected by the
pretreatment program. They are closest to
the problem and are already frequently
involved in related areas such as
regulation of sewers and collection of
user charges. Moreover, a local role in
pretreatment enforcement is consistent
with the partnership of Federal and local
effort found in the construction grants
program and other parts of the Act.
As those with the most immediate stake
in the success of the pretreatment
program, both in terms of protection of
the proper functioning of the POTW and in
terms of protection of the local
environment, local governments will be the
first line of defense. One way they may
exercise their crucial role is by means of
a local ordinance - a preferred route, and
one specifically preserved by the Act. It
is expected that each manager of a
treatment works would provide for such
standards." Local governments may also use
the citizen suit provisions of section
505. Section 505 is available because
local governments are "persons" as defined
in the Act "havinq an interest which is or
may be adversely affected". The citizen
suit provisions allow suit to enforce a
Federal or State pretreatment standard
either against the industrial user of the
POiW or against the State or Federal
government (for failure to take proper
action). The Agency anticipates tnat
pretreatment guidance published pursuant
to section 304(fj will be of assistance to
local governments in carrying out their
responsiblities.
The Agency believes that parallel
efforts of all three levels of government
will be needed for a successful
pretreatment program. To the maximum
extent possible, FPA will encourage and
assist State and local enforcement action.
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MUNICIPAL SEWER UTILITY FINANCING UNDEP. PL 92-500*
C. C. Taylor, Program Analyst
Environmental Protection Agency
1421 Peachtree Street, N. E.
Atlanta, Georgia 30309
ABSTRACT
The Water Pollution Control Act Amendments of 1972 imposed significant financial
requirements upon grantees under the Federal Construction Grants Program administered by
the Environmental Protection Agency. This paper discusses the legislative history and
implementation experience of these grant conditions which are commonly referred to as the
user charge and industrial cost recovery requirements.
All recipients of Federal construction grants must demonstrate legal, financial, and
managerial capability to complete construction and provide adequate operation and main-
tenance during the life of the facility. Grantees must also develop and implement user
charge systems whereby all users pay the costs of operation, maintenance and replacement
in proportion to their use of the treatment facility. Such charge systems must also in-
clude provisions for reimbursement of Federal construction costs allocable to industrial
users.
The Environmental Protection Agency's implementation of these statutory requirements
is impacting the institutional pattern of municipal sewer utility management. More
adequate operation and maintenance is assured, and greater equitability in the distribu-
tion of costs is being attained.
Public response to the imposition of user charges has been reasonably receptive.
Compliance with industrial cost recovery requirements continues to generate controversy,
particularly with respect to applicability, cost allocation, and accountability.
INTRODUCTION
During the long and somewhat torturous
legislative history of The Water Pollution
Control Act Amendments of 1972, the Honor-
able Robert E. Jones of the U. S. House of
Representatives characterized this legis-
lation for his collegues as follows: "Mr.
Chairman, this is an enormously complex
bill, and necessarily so, because our water
environment has become enormously compli-
cated because of the urbanization and in-
dustrialization of our society. Our legis-
lation must take into account the myriad
of the water needs issue" (1).**
Subsequent to enactment, the act has
been called many things, ranging from the
most significant legislation of the decade
to the most comprehensive, the most com-
plex and the most confusing legislation
ever enacted at any time or place in the
history of man. Whether or not either of
these latter characterizations are justi-
fied, PL 92-500 is, without doubt, compre-
hensive in scope. Many of its provisions
are complex, and implementation of some of
*Paper prepared for presentation at Fourth
U. S./Japan Conference on Sewage Treat-
ment Technology, Washington, D. C.,
October 28-29,1975.
**Numbers in parentheses designate refer-
ences on page 6.
643
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the provisions have been accompanied by some
confusion and controversy. This includes
implementation of significant provisions
relating to cost-sharing and cost alloca-
tion. The emphasis of this paper is fo-
cused upon these financial aspects of the
subject legislation.
BACKGROUND OF PL 92-500
In the spring of 1967, a joint Commit-
tee of the American Public Works Associa-
tion, the American Society of Civil
Engineers, and the Water Pollution Control
Federation reviewed the most significant
problems of the broad area of administra-
tive, legislative, and financial issues of
municipal water and sewer service. As a
result of the initial review, the Commit-
tee decided to focus its activities upon
the most urgent area, namely wastewater
financing and charges (2). This was indic-
ative of the general conclusion that most
of our municipalities were not adequately
prepared, at that time, to assume and
manage the rapidly escalating financial
and administrative responsibilities of
sewer service.
A leading management consultant firm,
working under contract with EPA Region
VIII, found this general situation little
changed by 1972 (3). Our nation is, of
course, geographically large and widely
diverse with respect to political structur-
ing. Obviously, this broad generalization
did not apply to all municipalities indivi-
dually. However, as a general rule, munic-
ipal sewer utilities were operated largely
as a public service financed by annual
appropriations from general revenues.
Generally, cost accounting systems, and
their attendant legal and financial insti-
tutions were not adequate for efficient
operation as financially self-sustaining
public utilities. It was in this atmos-
phere that The Congress deliberated legis-
lation which culminated in PL 92-500.
During this legislative process, many
complex and controversial issues were dis-
cussed and debated, after which some were
resolved and some apparently compromised.
These deliberations are reflected in the
'Committee and conference report (1).
Of the significant issues debated, two
pertain directly to our subject of finan-
cial management. First, Congress fully
recognized that the costs of attaining
the desired levels of clean water were
going to be large - we might even say
enormous.
The most recent "Needs Survey" cost
estimate for the backlog of municipal
facilities which are normally funded under
the EPA Construction Grant Program - that
is, only treatment facilities and attendant
interceptors and outfalls - was at the
level of approximately 50 billions of
dollars (4). We have known for some time
that attainment of the desired levels of
pollution control was going to be costly,
and Congress was fully aware of this as
they legislated this act.
Second, the committee reports reflect
that Congress also was fully aware of the
basic necessity of getting maximum return
for each dollar of this enormous investment
and that this could be done only with im-
proved and adequate operation and mainte-
nance. Why go to the expense of building
these facilities if they were not going to
be operated and maintained in such a way
that they would do the job for which they
were designed?
As a result of these deliberations,
the Congress reached some basic decisions.
First, the level of Federal cost sharing
for the construction costs of the large
backlog of needed publicly-owned municipal
facilities would be raised to 75 percent.
Second, it would be necessary to find
some way to move our municipal sewer sys-
tems to a sounder financial basis whereby
thev could become more financially self-
sufficient. This should be done by pro-
moting a shift of the sewer service
function from a public service basis to a
public utility basis whereby;
a. Wastewater treatment and control
service would be paid for by the
users of that service.
b. The users would pay these costs on
the basis of the extent of their
use of the system. In this way,
there would be an economic and
financial incentive to reduce
waste discharge or at least hold
it to an amount for which each
user would be willing to pay.
Third, after extended, and apparently,
heated debate about the Federal funding of
644
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publicly-owned facilities which would
treat industrial wastes, the Congress
reached this basic conclusion. The Feder-
al Construction Grant Program was ini-
tially designed to provide Federal funding
aid to municipalities for the large back-
log of needed facilities. Consequently,
it would not be appropriate for this fund-
ing program to provide a subsidy to indus-
trial users of municipal facilities. This
would be significant economic and financial
discrimination against those industries
that did not have the opportunity of
discharging to municipal, publicly-owned
facilities (5).
These conclusions are articulated in
Section 204(b)(l) of PL 92-500 in the
form of three basic provisions:
1) For all projects funded with
Federal construction grants, the
grantee must demonstrate legal
and financial capability to com-
plete construction of the
facilities and to adequately
operate and maintain the facili-
ties throughout their useful
life.
2) The grantee must agree' to develop
and put into effect a user charge,
sewer service fee system whereby
all users of the system will pay
a share of the operation, main-
tenance, and replacement costs
in proportion to their use of
the system.
3) For all such grant assisted pro-
jects that treat industrial
waste, the charge system must
include provisions for industrial
users to pay back to the grantee
their proportional share of con-
struction costs, at least to the
extent of the Federal grant.
The latter two provisions were essen-
tially new limitations of the Federal Con-
struction Grants Program, and EPA experi-
ence with their implementation impinges
upon the current pattern of municipal
sewer utility management. These are the
provisions of PL 92-500 commonly referred
to as the user charge and industrial cost
recovery grant requirements (6).
EPA EXPERIENCE WITH USER
CHARGE AND INDUSTRIAL COST RECOVERY
GRANT CONDITIONS
User Charges For OM&R Costs
It is clearly apparent that the pri-
mary objective of the statutory require-
ment for a user charge system is to assure
sufficient revenue for adequate operation,
maintenance, and replacement of operational
components during the useful life of the
grant-assisted facility. There has been
almost universal acceptance of this objec-
tive, in principle. With the exception of
some normal resistance to rapidly increas-
ing charges as higher levels of treatment
are installed, the users of municipal sewer
service have been quick to grasp the logic
of maximizing returns from these large
capital investments through more efficient
operation and maintenance. Likewise, they
appear to have readily accepted the
necessity of raising sufficient revenue for
this objective. There has been far less
universal acceptance of the source of
revenue and the distribution of these
revenues as required by interpretation of
the statute.
At the time this legislation was in-
acted, a significant proportion of our
municipalities obtained some or all reve-
nues for provision of sewer services from
ad valorem property taxes and other non-
user sources. Many municipalities continue
to do this for some components of total
costs.
In consideration of Congressional
recognition of the diversity of legal and
financial factors that existed among juris-
dictions, EPA proceeded to draft regula-
tions which would permit reasonable flexi-
bility in the design of user charge systems
that would meet the unique requirements of
each grantee jurisdiction (5). This inter-
pretation proposed approval of user charge
systems including ad valorem tax revenues
for OM&R costs if the grantee could demon-
strate that revenue was reasonably propor-
tional to sewer use among major classes of
users.
The Comptroller General of the United
States ruled that such user charge systems
would not meet the statutory requirements
for proportionality between classes of
users nor among users within classes (7).
645
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Therefore the grant condition currently re-
quires that all OM&R revenue, including
revenue for costs allocable to non-exces-
sive infiltration/inflow and stormwater
treatment, be obtained from user charges.
This categoric requirement continues
to be controversial and causes implementa-
tion problems particularly where there is
a long established custom of relying on
property tax revenue and where municipal-
ities find it expedient to continue to do
so for funding of local capital costs. The
latter practice, of course, necessitates
carrying the costs of legal and institu-
tional arrangements incident to the two
or more sources of revenue.
As a consequence of this experience,
EPA has requested amendment of the statute
to permit use of ad valorem based user
charge systems under certain qualified con-
ditions. This amendment is now pending
before Congress.
Another significantly controversial
aspect of the user charge grant condition
is the criteria of average-unit pricing
with no significant quantity discounts. We
have a long historical pattern of public
utility rates based upon marginal-unit
pricing, affording significant quantity
discounts to large-volume users. Such a
pattern applied to most public utility
services such as electric power, natural
gas, water supply, and sewer service.
In order to provide an economic and
financial incentive to minimize waste dis-
charge as well as promote the principle of
imposing the costs of pollution abatement
directly upon the source, the statute was
drawn to require that user charges for
OM&R be based directly upon factors that
significantly affect those costs. Although
our agency implementation policy provides
for considerable flexibility in the alloca-
tion of OM&R costs among parameters of flow
and flow characteristics, as well as flexi-
bility in the allocation of costs not di-
rectly related to these parameters, our
policy requires essentially uniform rates
for comparable services among all users.
This grant limitation criteria often
accounts for the most significant shifts
in relative cost distribution among
classes of users, particularly for a shift
in relative cost burden from the residen-
tial class to the industrial class. Ob-
viously, the extent of change in either
the magnitude of costs or the relative
distribution of those costs is dependent
upon previous levels of service and charges
with which current conditions are compared.
EPA regulations require that the
grantee implement the user charge system
throughout the entire service area to cover
OM&R costs on all facilities. We are
pleased to learn that this criteria has
encountered relatively few problems with
the exception of some difficulties in ob-
taining necessary agreements with recipient
communities in regional systems.
Although our agency experience is re-
latively limited, there seems to be little
doubt that operation and maintenance will
be materially improved by assurance of more
adequate revenues. As the pollution abate-
ment cost burden inevitably increases, our
experience would appear to indicate that
the attainment of greater equitability is
also conducive to accomplishing our major
water quality goals.
Industrial Cost Recovery of Federal
Construction Costs
As previously indicated, a significant
Federal construction grant condition is the
requirement for reimbursement of Federal
construction costs allocable to industrial
users. Although there is a long precedent
for such reimbursement of Federal funding
in the water resource development field,
this feature is entirely new to the Federal
grant program for sewer construction.
Immediately subsequent to enactment,
there was public criticism from the indus-
trial sector. Industrial users of munici-
pal systems expressed resentment at being
the only beneficiaries required to reim-
burse the grant assistance. This argument
was supported by the contention that they
were fully comparable contributors to the
general revenues from which these grant
funds are appropriated. Although this
criticism has not disappeared, it has
apparently mitigated as industrial dis-
chargers become more aware of the relative
costs of using publicly-owned municipal
systems as compared with privately-owned
facilities.
KPA implementation problems are more
closely related to the technical complex-
646
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ities of applicability, cost allocation,
and accountability. Perhaps the best
indication of the scope of these difficul-
ties is the fact that promulgation of fi-
nal agency guidelines is just now nearing
completion.
It was apparently an objective of
Congress to impose this differential reim-
bursement requirement upon commercial
process wastes from the production of con-
sumer products for which pollution abate-
ment costs could be shifted to product
prices. In our diverse, but highly inte-
grated and industrialized society, this
delineation of applicability has not
proved to be easily attained. Such a
criteria clearly extends beyond the
manufacturing category. EPA regulations
define applicability to include A, B, D,
E, and I divisions of our Standard In-
dustrial Classification System (8).* This
includes the service industry. Exemption
from industrial cost recovery is provided
for discharges that are primarily segre-
gated domestic wastes from sanitary
conveniences. This whole complicated
criteria has almost defied practical im-
plementation.
Although the issues of cost alloca-
tion are somewhat amenable to technical
analyses, such analyses have not yet
attained commonly accepted precedents for
the parameters of allocating costs nor for
the distribution of construction costs
among these parameters. Our regulations
provide for considerable flexibility, in
recognition of the fact that these will
vary significantly by type of facility and
level of treatment. In the absence of
fairly rigid implementation criteria,
continuing controversy apparently can be
expected as representatives of major user
classes compete for financial advantage.
In accord with the statute, the
grantee is charged with specific respon-
sibility for collection of the industrial
cost recovery revenues. The grantee
reverts one-half of this revenue to the U.
S. Treasury and retains the remainder.
Eighty percent of retained revenues must
be used for expansion or replacement of
eligible facilities. The eligible project
costs for subsequent grants are reduced
by the amount of unexpended funds re-
tained for expansion and replacement.
The reaction of grantees to the indus-
trial cost recovery requirement has been
less than enthusiastic approval. This is
apparently due largely to the rather heavy
administrative burden for which they often
seem to feel they have no incentive to
assume. This introduces what now appears
to be a most significant implementation
problem for EPA. Although our implementa-
tion experience in this area is just begin-
ning, the problems of monitoring and audit
accountability are significant. The grant
conditions will require multiple accounting
procedures for the various revenue accounts.
They may also result in multiple cost allo-
cation and amortization procedures for the
various components of total costs. These
additional requirements impose upon an
institutional framework that was inadequate
to the task even prior to this imposition.
This brief discussion of some of the
more significant implementation problems
should be considered tentative and somewhat
exploratory. EPA feels that progress is
being made and the agency is actively
exploring the potential for improvements
both within the framework of the existing
statute, as well as possible statutory
modifications (9)(10). Such considerations
are being focused particularly upon the
issues of cost sharing and financial manage-
ment. It is hoped that our experience is
of interest to you and may be of some help
to you as we pursue our mutual goal of an
improved environment.
*A-agriculture, forestry and fishing; B-
mining; D-manufacturing; E-transportation,
communications, electric, gas and sanitary
services; and I-services.
647
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REFERENCES
1) A Legislative History of The Water Pollution Control Act Amendments of 1972,
Committee Print Serial No. 93-1, Library of Congress, Vol. 1, January 1973,
page 356.
2) Financing and Charges For Wastewater Systems, A Joint Committee Report, American
Public Works Association, American Society of Civil Engineers, Water Pollution
Control Federation, 1969.
3) Financial and Institutional Arrangements For Wastewater Management, Denver SMSA,
by Wilbur Smith and Associates, Environmental Protection Agency, April 1973.
4) Cost Estimates For Construction of Publicly-Owned Fastewater Treatment Facilities,
1974 "Needs" Survey, Final Report to the Congress, Environmental Protection Agency,
Revised May 6, 1975.
5) Report of The Committee on Public Works United States Senate, Together with
Supplemental Views to Accompany S2770, Report No. 92-414, USGPO, Washington,
D. C., 1971, pages 28-30.
6) Public Law 92-500, 92nd Congress, S2770, October 18, 1972, Section 204(b)(l).
7) Comptroller General of the United States, Decision File B-166506, July 2, 1974.
8) Standard Industrial Classification Manual 1972, Executive Office of The President,
Office of Management and Budget, USGPO.
9) Evaluation of Alternative Methods For Financing Municipal Waste Treatment Works,
Socioeconomic Environmental Studies Series, Office of Research and Development,
EPA, 600/5-75-001, February 1975.
10) Analysis of Cost Sharing Programs For Pollution Abatement of Municipal Wastewater,
Socioeconomic Environmental Studies Series, Office of Research and Development,
Environmental Protection Agency 600/5-75-031, November, 1974.
648
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A PERSPECTIVE ON MUNICIPAL POLLUTION CONTROL -
THE CONSTRUCTION GRANTS PROGRAM & PL 92-500
John T Rhett
Deputy Assistant Administrator
Office of Water Program Operations
U S Environmental Protection Agency
Washington, D C 20460
ABSTRACT
The Federal Water Pollution Control Act Amendments of 1972 provide for an $18 billion
program for construction of municipal wastewater treatment works. Almost $11 billion of
that sum remains to be obligated. However, the pace of obligations is rapidly increasing
to a goal of $400 million per month. Problem areas encountered in implementing the program
in its first three years include the 1977 deadline for secondary treatment, user charge
requirements, program management, personnel needs and participation of State agencies.
Specific actions to remedy these problems have been taken, including proposing amendments
to the law. Several major areas of the program wilI receive attention in the future
including institutional systems, operation and maintenance, development and demonstration
of new technology and construction needs and priorities. EPA expects to make recommenda-
tions to Congress on future funding of the program.
TEXT
My topic today, the Federal Water
Pollution Control Act, as amended in 1972,
is a subject that gives me great pleasure
to address. I appreciate this opportunity
to comment on the strengths and shortcom-
ings of the law, and some current admini-
strative and legislative initiatives as
they pertain to the Municipal Water Clean-
Up Program.
Since one of our major administrative
tasks under the law is to provide funds to
get construction of municipal treatment
works rapidly underway, I am happy to
report first on the status of obligations.
As you may know, obligations are Federal
funds that are committed as grants to cover
75 percent of the eligible costs of specific
municipal wastewater treatment construction
projects. And, our EPA grants program is
quickly becoming the world's largest single
pub Ii c works program. A I most $ I I b i I I ion
rema i ns from our $18 billion author!zation,
and we are moving quickly to obligate all
of that sum by the statutory deadline,
September, 1977.
Currently, our obligations under the
new law have reached over $7 bi I I ion and
projects being completed under the old law
have grants of $4.3 billion. Further, our
monthly obligation rate in FY 1975 averaged
about $186 million over the FY 1974 rate.
We went from $115 mi I I ion to over $300
million, and we confidently expect to raise
our average over $100 million more to reach
our goal of over $400 million per month for
this fiscal year.
I am a I so pleased to report that the
Federal reimbursement program to municipal-
ities is almost completed. This is for
construction begun in advance of the Federal
grant, and which is considered eligible for
a grant. Over $1.6 billion has been obli-
gated and over $1 billion paid out. And,
the half a billion dollars in remaining
funds are presently being awarded.
649
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Translating investments into projects
we have more than 4,000 individual projects
funded at 75 percent underway and almost
2,000 additional projects still being com-
pleted under the old law. Once finished.
our new law projects will constitute a $24
billion total investment in public waste-
water treatment works, and added to the
public wastewater treatment works we have
under the former grants program, our
national treatment investment would approx-
imate $42 billion by the year 1977,
At the present date, we are almost
half-way towards our goal of obligating all
the grant monies that were authorized under
PL 92-500, but the most heartening fact in
this report is the rate at which the fund-
ing levels have increased this past year.
The progressive picture today presents a
contrast with the program in earlier days.
To appreciate our progress and the initia-
tives and actions that are currently pend-
ing, we must step back in time.
By last year the criticism directed
at the program and the law, PL 92-500, had
mounted to a very high level. The concerns
that were voiced were so general they
caused questioning of the program's
credi bi Ii ty.
To cite just a few of the major
issues, critics attacked:
—The goals of the Act. "They were
impossibly idealistic."
—The funding of the Act. "It was
inadequate to meet the 'needs'.''1'
—And the deadlines were "unreal-
i stic."
None of the legal mandates antici-
pated the capital funding requirements nor
the local difficulties in raising the
matching share of 25 percent. Moreover,
as delays lengthened, the costs continued
escalating. Construction costs had risen
at the rate of 15 percent per annum, and
only recently have they shown any signs of
abatement.
The secondary treatment deadline,
within the Act, and the need to amplify
the States' role have also called for
legislative change. Since many of the
project planning decisions that must be
made are based primarily on "best judgment,1'
and the best planning information i's
ocated at the State and municipal level,
the lack of any real provision for State
participation has riveted our attention.
At a less fundamental level, often
there are pleas to simplify the law, to
cut "red tape" and paperwork. Indeed,
this is incorporated in a provision of the
law, in Section IOI(fl. The classic reply,
of course, is in the law itself. That
section appears on page 2, but the law
continues for another 86 pages of fine
print, and almost every page calls for
more regulations, guidelines and reports.
Personnel at a I I levels of the effort
in both the public and private sectors
have generally been too few. In facilities
planning, for instance, no less than ten
major categories of requirements must be
cons i dered.
Also, there has been the requirement
for an equitable system of user charges.
The requirement was conceived as an incen-
tive to water and sewer customers to con-
serve water and cut individual use. Un-
fortunately, the requirement also placed
large administrative and cost burdens on
communities with existing ad valorem
property-based methods of taxation. On
this subject, a California State Repre-
sentative recently testified that it would
cost the Sanitation Districts in Los
Angeles County, not including Los Angeles
City, over $2 million a year in additional
accounting expenses to administer the
required system. In short, the user
charge concept was environmentally sound,
but it was fiscally unsound, in some cases.
It failed to take into account established
local, revenue-raising practices or the
administrative costs of change.
The recovery of the industrial share
of treatment construction costs is an
allied subject, but since Mr. Taylor will
be addressing that area of the law, I wi I I
pass over some recent developments there.
So far, I have mentioned only a few
of the issues that have "cropped up. -
As you know, there have been others, and
it sometimes seemed last year that the
issuance of almost all the required,
baseline regulations and guidance by the
Agency went largely unnoticed.
650
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But, that was last year, and the year
before, This year, I am happy to note that
our progress has been pa.pid, and our momen-
tum Is gaining strength. There are several
reasons for this and the chief factors, I;
believe, are the experience we have so
painfully gained, and the widespread cooper*
ation we have enjoyed in devising, and
implementing the needed changes,
It is also true that "nothing
succeeds like success.^ Recent progress
has bred a spirit of optimism in the pro-
gram. We have been moving to simplify
procedures and strengthen management, and
where changes are not legally permissible
because the law is over specific, we have
been promoting legislative amendments.
Concerning the administrative changes,
last November, as the result of some rn-
depth study and program analysis by our-
selves and others, we began meeting with
representatives of the various interest
groups involved in the program^—the State
and local governments, the consulting
engineers, contractors, and wastewater
equipment manufacturers.
The recommendations and strong
cooperation we have recently received have
enabled us to further simplify and stream-
line the granting procedures and provide
guidance in fulfilling them, particularly
for those applying to the earliest stages
of planning. We have also improved our
monitoring capabilities, to project future
funding commitments and identify lags and
individual projects needing action. We
have reorganized for more central manage-
ment and accountability for the individual
projects and the program as a whole, In
the Regions and in Headquarters. Since we
have received authorization, we are cur-
rently recruiting and instituting training
for 400 additional positions in the program.
But most important, for some time, we have
been encouraging the States to assume large
parts of the program by assuming larger
review and certification responsibilities
for project plans and specifications and
for reviewing infiltration/inflow and
operation and maintenance provisions. We
are also helping the States to strengthen
their own program activities through
increased Section 106 funds, and urging
the use of part of the construction grants
funds, i f needed.
In this latter effort, we have suc-
ceeded in encouraging more than half the
States to assume extra grant responsibil-
ities. Their management cost increases can
currently be covered by withdrawing a sum
up to one-half of one percent of their
total Federal allotment, and the State of
California is taking advantage of this
funding option. Alternatively, our EPA
budget that is presently before Congress
for approval contains extra funding
requests to strengthen the States'
programming and planning capabilities.
Cumulatively, there has been a good
deal of action on the management side this
past year, When I consider the total
impact of the recent and emerging develop-
ments, I am greatly pleased with our pro-
gress in the program. In addressing the
problem areas, we have introduced a good
deal of administrative flexibility.
For the areas we have been unable to
address administratively, new legislation
has been introduced, A bill to amend
PL 92-500, H,R 9560, is currently await-
ing further attention by the House Public
Works Committee, Our Administrator,
Mr, Train, testified on it at some hear-
ings recently. Briefly, its major grant-
impacting provisions are these:
— First, it does contain a provision
a I lowing ad valorem taxation to assess
user charges. However, we believe it is
over-broad and should be limited to only
those areas where it has been used
histori caIly.
—Second, it does delegate the
major construction granting authority to
the States. Since we have been working
closely with the Public Works Subcommittee
on this amendment for some time, and
although we do have reservations on the
procedure for suspending State certifica-
tion, we are, for the most part, pretty
welI satisfi ed wi th it.
—Third, it does extend the secon-
dary treatment deadline to July, 1982. On
this issue, the Administrator felt the
extension should be granted until July,
1983 when Best Practical Treatment would
be required. He also indicated the exten-
sions should be on a case-by-case basis,
and the non-availability of Federal fund-
ing should be a justification for granting
651
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an extension. Ocean discharging municipal-
ities, we feel, should not be singled out
in the amendment since their discharges can
be considered for extension along with the
others, if the delay is merited.
Parenthetically, the Task Force on
Municipal Ocean Outfalls recommended that
ocean dischargers, where the need for
secondary treatment is uncertain, should
have prime consideration for Step I planning
grants to determine their water quality
impacts, but should not be given much
priority for construction grants, unless
indicated by the Step I study.
The remaining provisions of the bill
relate to increased funding for State pro-
gram and areawide planning above what we
requested in our Agency budget. As
Mr. Train indicated, we disapprove extend-
ing areawide planning under Section 208
beyond the initial two years, nor should
the 75 percent Federal funding share be
increased to 100 percent, as proposed.
Encouragement of strong local parti-
cipation in planning should be premised on
some degree of funding commitment by the
localities directly involved. As for the
bill's proposal to provide more funds to
reimburse advanced construction, we did
not support this because we do not think
it would buy any additional clean-up of
the waters.
Taken all together, and especially
if our recommendations are adopted, we
feel that the bill will significantly
alleviate the short-term problems of the
program.
As for the longer-term problems
affecting the more distant water quality
goals of the law, the National Water
Quality Commission's findings, which will
be discussed later, when they issue in
final form, will be a prime factor next
year in determining the final form these
goals will assume. Based on the draft
version of the staff report that is
currently circulating, I am very encouraged
by the fact that the municipal treatment
costs seem pretty close to our own projec-
tions, and the tone seems generally favor-
able to continuation of the effort.
Looking ahead in the program, I see
several major areas of concern. What is
particularly needed right now, it seems to
me, is more information on the institu-
tional systems, in the localities and
particularly the States, that increasingly
are becoming involved; on the stresses
and strains on these systems; and some
assessment of the abilities needed to
assume the more substantive parts of the
program.
Another concern is with the preserva-
tion of adequate operations and mainten-
ance in the plants. As more plants with
more sophisticated treatment equipment
go on line, operating efficiency will be
assuming even greater importance. For
these reasons, we have begun actions to
strengthen the States' capabilities in
operator training and certification
programs, also in monitoring.
A third concern is to encourage the
development and demonstration of innova-
tive wastewater treatment technology. We
are presently in the early stages of
developing some possible new legislative
initiatives to fill this program need
which, hopefully, will be ready for pro-
posal to Congress next year.
Finally, we are concerned with the
new State Needs Survey that is just about
to get underway. As you may know, we
hope to identify from it where we are in
terms of reaching our goals, and how far
we need to go. In conjunction with this,
we will also be scrutinizing closely the
State priority lists to be sure the
important selection criteria are empha-
sized. We want to be sure the public
funds are not misapplied to projects with
marginal benefits to water quality and
that the needs that Congress has identified
in the law — for advanced and secondary
treatment and for interceptor sewers —
receive first consideration. We want to
be sure, in order that we reach our
national goals as quickly as possible,
that projects emphasized first are those
in the critical water quality areas that
are required to meet the standards and
enforcement provisions of the law.
While on the subject of needs and
priorities, I would like to point out
that the largest need 1 foresee in this
program is for some assurance of future
funding continuity. Municipalities should
have some assurance the funds will be
there to build and complete their projects
before they willingly commit themselves
652
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to raise the local funds to pay for planning.
Commitments should be made on all sides,
and the communities should not have to live
under the threat of on-again, off-again
Federal assistance.
To learn the views of the public and
the professions on how the program should
be financed beyond the current authoriza-
tions, and how the secondary treatment
requirements for municipalities by 1977 or
1978 should be treated when they would be
unattainable, EPA held a series of public
hearings last June. In summing up the
results, as a whole we found a consensus
on the necessity to achieve secondary
treatment or higher, as required by water
quality considerations. Also, we found
some support for giving stormwater treat-
ment less emphasis and a lesser priority
status, and on extending the 1977/1978
secondary treatment deadline on a case-by-
case basis.
After we evaluated these responses
and recommendations, we made some estimates
based on the cost figures for the 1974
State Needs Survey. As you may know, the
total State needs identified in the 1974
Survey, as adjusted, would cost over $342
billion, including the cost of treating
and controlling stormwaters, at $235
billion. Since this total sum was just
too large to be seriously contemplated,
we examined the individual treatment cate-
gories in terms of the priorities of the
Act, and their relative impact in attain-
ing cleaner water. And we excluded the
$235 billion for stormwaters. Since our
purpose was to devise a strategy to
"optimize" Federal funding, we chose pro-
jects to provide secondary and advanced
treatment, and interceptor sewers, and to
correct sewer infiltration/inflow problems
for primary funding emphasis.
And based on our findings and esti-
mates, we expect to make recommendations
to the Congress on how the program should
be financed in the future. As you may
know, we favor a varied Federal funding
share depending on relative importance to
our clean water goals. And needless to
say, this would be premised on continued
program funding at a higher level for
several more years, following the lapse
of the current PL 92-500 authorization.
Parenthetically, I understand Japan
is also moving to greatly increase its
national funding to municipal treatment
projects. I would like to encourage
Japan in the significant commitment that
will be proposed for national endorsement,
The five-year, $30 billion program that
is planned, if adopted in its entirety,
would constitute a 400 percent increase
over Japan's present level of program
funding for such construction. I commend
your dedication to this significant and
laudable water clean-up effort.
In conclusion, I would like to
mention some ancillary benefits we expect
to derive from the program. Aside from
improved water quality — and since the
projects under PL 92-500 are not yet
completed, the progress we are seeing is
primarily derived from our predecessor
law — one major benefit is to the
nation's economy. For instance, employ-
ment on the public treatment works is
expected to reach a peak of 296,000 new
jobs per year in 1977, and remain at over
100,000 jobs through 1983. Overall, in
the decade between 1975 and 1985, the
National Water Quality Commission has
tentatively estimated that implementation
of the Act could create a total of nearly
one and one-half million man years of
work to construct the required treatment
works. And the "ripple effect" in the
economy wi I I probably create an equal
number of additional jobs.
This is a substantial benefit to
the nation, but we are not losing sight
of our basic objectives — to clean up
our water in the most cost-effective
manner possible.
In pursuing this goal, we welcome
the opportunity to exchange information,
technology and experience with our
Japanese counterparts. Although you
operate under different laws, our overall
goals are similar. I believe these
exchanges are valuable to our own water
clean-up program, and I wish to take this
opportunity to thank the Japanese Govern-
ment for your significant contributions
to improving the water environment of
the world.
Thank you.
653
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COMMISSION CHARGE
TENTATIVE STAFF ISSUES AND FINDINGS
NATIONAL COMMISSION ON WATER QUALITY
J. G. Moore, Jr.
Program Director
National Commission on Water Quality
Washington, D. C.
INTRODUCTION
On October 18, 1972, the Congress over
a Presidential veto, enacted Public Law
92-500 — the Federal Water Pollution
Control .Act Amendments of 1972. Respond-
ing to public demand for cleaner water, the
law it enacted culminated two years of
intense debate, negotiation and compromise,
and resulted in the most assertive step
in the history of national water pollution
control activities.
In their deliberations, Congress
determined that the prior program was
making too little headway in redressing
the serious problems of the Nation's
polluted waters. John Blatnik, then
Chairman of the House Public Works Com-
mittee, testified to the new sense of
immediacy of the task at hand -- cleaning
up the Nation's waters:
"In this measure, we are totally re-
structuring the water pollution control
program and making a far-reaching national
commitment to clean water, much as our
space program was restructured a decade ago,
when the late President Kennedy committed
America to a landing on the moon before
the end of the 1960s."
Senator Muskie, bringing the Bill to
the Senate floor, stated:
"...today, the rivers of this country
serve as little more than sewers to the
seas. Wastes from cities and towns, from
farms and forests, from mining to manufac-
turing, foul the streams, poison the
estuaries, threaten the life of the ocean
depths. The damage to health, the envi-
ronmental damage, the economic loss can
be anywhere."
The Act, P.L. 92-500, departed in
several ways from previous water pollution
control legislation. It expanded the
Federal role in water pollution control,
increased the level of Federal funding
for construction of publicly owned waste
treatment works, elevated planning to a
new level of significance, opened new
avenues for public participation and
created a regulatory mechanism requiring
uniform technology-based effluent standards,
together with a national permit system for
all point source dischargers as the means
of enforcement.
In the strategy for implementation,
Congress stated requirements for achieve-
ment of specific goals and objectives
within specified timeframes. The objective
of the Act is to "restore and maintain the
chemical, physical, and biological integrity
of the Nation's waters." In addition, two
goals and eight policies are articulated.
The goals are:
-- To reach, "wherever attainable", a
water quality that "provides for the pro-
tection and propagation of fish, shellfish,
and wildlife" and "for recreation in and on
the water" by July 1, 1983.
-- To eliminate the discharge of pol-
lutants into navigable waters by 1985.
654
-------
The policies are:
-- To prohibit the discharge of toxic
pollutants in toxic amounts.
— To provide Federal financial assist-
ance for construction of publicly owned
treatment works.
-- To develop and implement areawide
waste treatment management planning.
-- To mount a major research and
demonstration effort in wastewater treat-
ment technology.
-- To recognize, preserve and protect
the primary responsibilities and roles of
the States to prevent, reduce and eliminate
pollution.
-- To insure, where possible, that
foreign nations act to prevent, reduce and
eliminate pollution in international waters.
-- To provide for, encourage and
assist public participation in executing
the Act.
-- To pursue procedures that drasti-
cally diminish paperwork and interagency
decision procedures and prevent needless
duplication and unnecessary delays at all
levels of government.
The Act provides for achieving its
goals and objectives in phases, with
accompanying requirements and deadlines.
Phase I, an extension of the program
embodied in many State laws and Federal
regulations, requires industry to install
"best practicable control technology
currently available" (BPT); and publicly
owned treatment works to achieve secondary
treatment -- by July 1, 1977 -- as well as
"anymore stringent limitations, including
those to meet (State or Federal) water
quality standards." (Sec. 301(b)(1)(C)).
Phase II requirements are intended to
be more rigorous and more innovative.
Industries are to install "best available
technology economically achievable (BAT)...
which will result in reasonable further
progress toward the national goal of
eliminating the discharge of all pol-
lutants"; and publicly owned treatment
works are to achieve "best practicable
waste treatment technology... including
reclaiming and recycling of water, and
confined disposal of pollutants" (BPWTT)
-- by July 1, 1983 — as well as any water
quality related effluent limitation. (Sec-
tion 302) Ultimately, all point source
controls are directed toward achieving the
national goal of the elimination of the
discharge of pollutants by 1985.
The Act was intended to be more than
a mandate for point source discharge control
It embodied an entirely new approach to the
traditional way Americans have used -- and
abused -- their water resources. Some of
these mechanisms are found in Title I, the
broad policy title; others are woven
through-out the Act in grants and planning,
in standards and enforcement and in permits.
The second section of the Act requires
the development of comprehensive programs
for preventing, reducing and eliminating
pollution, and further asks for research
and development aimed at eliminating
unnecessary water use. In Section 208,
the statute directs the designation of
areawide institutions to plan, control and
maintain water quality and reduce pollution
from all sources through land use or other
methods.
Construction grants for publicly owned
treatment works are made available to en-
courage full waste treatment management,
providing for:
"(1) the recycling of potential sewage
pollutants through the production of agri-
culture, silviculture, and aquaculture
products, or any combination thereof;
"(2) the confined and contained
disposal of pollutants not recycled;
and
"(3) the reclamation of wastewater;
"(4) the ultimate disposal of sludge
in a manner that will not result in envi-
ronmental hazards."
The grantees are encouraged to combine
with other facilities and utilize each
other's processes and wastes. Facilities
are to be designed and operated to produce
revenues.
These statutory provisions outline a
long-term program to reduce water use, re-
duce the generation of wastes and establish
655
-------
financially self-sustaining publicly
owned pollution control facilities.
Congress recognized it was placing
demands on people, technology, the economy
and public and private institutions which,
ultimately, would determine the success of
the program. There was uncertainty as to
whether the required technologies existed;
how the new law's implementation might
affect society, the economy, and the
environment; and how well the institutional
system would or could respond to this de-
manding new law.
The Commission was established by
Section 315, to determine if a mid-course
correction was needed between 1972 and
1983, and to report its findings, con-
clusions and recommendations to the Congress
within three years from the law's enactment.
COMMISSION CHARGE
The Commission's charge is:
To "...make a full and complete
investigation and study of all the tech-
nological aspects of achieving, and all
aspects of the total economic, social, and
environmental effects of achieving or not
achieving, the effluent limitations and
goals set forth for 1983 in Section
301(b)(2) of this Act."
The Commission determined "that a
comprehensive study of the goals and
requirements for 1983 cannot be properly
undertaken without attention to the progress
made toward clean water by industries and
municipalities under the 1977 requirements."
It stated that it would "examine progress
toward the 'elimination of the discharge of
pollutants' as an indicator of what will
remain to be done after 1983."
Because of the specific statutory
charge, the goal and effluent limitations
for 1983, and the impacts of their applica-
tion have remained the primary focus of the
Commission's attention. In the time per-
mitted, no study could assess all the far-
reaching implications of each of the Act's
provisions. Limitations of data, time and
resources, as well as evolving knowledge
and issues, restrict what can be done and
still meet deadlines. The Commission has
completed a major undertaking and has
produced new and useful information for
the Congress. The Commission concludes
its assignment with the knowledge it has
both answered and generated questions. Its
report contains the following components:
Chapter I -- An analysis of the capabili-
ties and costs of technology for
achieving the effluent limitations
required by 1977 and 1983, as well as
a look at what remains to be done after
1983;
Chapter II -- An assessment of the capabi-
lity of the public and private sectors
to apply the defined effluent limita-
tions for 1977 and 1983, as well as
those more stringent to protect water
quality;
Chapter III -- An analysis of the economic
effect of the cost of applying the
necessary technologies on both a
macroeconomic and microeconomic scale
-- as well as the social effects of
these changes;
Chapter IV -- A description of present water
quality and environmental (water-
based and related terrestrial) condi-
tions, and projections of anticipated
change which may result from imple-
mentation of the Act.
Chapter V -- Identification of the effects
in several selected regions of the
Nation; and
Chapter VI -- An assessment of the public
and private response as the institu-
tional segments finance, implement,
manage and enforce the Nation's water
pollution control program.
[The discussion which follows presents the
Commission staff's tentative summary of the
issues and findings. Recommendations will
be formulated by the Commission as it
completes its deliberations and concludes
its work.]
656
-------
CAVEAT
Commission studies performed by con-
tractors often provide a range of costs
and benefits for differing technologies,
conditions, or assumptions. Complete and
reliable data were not always available
covering all questions the Commission and
contractors have analyzed; every effort is
made to explain methodologies and to qualify
estimates in the full text of the Commission
staff draft. In the following summary,
reflecting this variability has been sac-
rificed for the sake of brevity. There-
fore all cost and expenditure estimates and
quantified statements of effects should be
regarded as staff best professional judgment
rather than as exact measures of these items.
The staff recognizies that others might have
chosen other figures for different reasons.
CAVEAT
NOTE: All dollar figures are stated in
June 1975 dollars.
I. Progress Under 1977 Requirements
Question: How will progress toward
achieving the 1977 requirements affect the
timetables for "achieving or not achieving
the effluent limitations and goals set
forth for 1983"?
Answer: The effect is to delay
achievement of 1983 requirements and goals.
Slow progress toward achieving secondary
treatment by publicly owned treatment works
by July 1, 1977, will delay achievement of
"best practicable waste treatment technology
over the life of the works" by 1983.
Similarly, but to a lesser degree, indus-
tries and agriculture not achieving "best
practicable control technology currently
available" by July 1, 1977, will delay
achievement of "best available technology
economically achievable" by July 1, 1983.
A. Technological Aspects - 1977
Publicly Owned Treatment Works - 1977
Question: Is secondary treatment for
publicly owned treatment works as defined
by the Administrator of the Environmental
Protection Agency technologically achie-
vable?
Answer: Yes.
Question: Will all publicly owned
treatment works achieve secondary treatment
by July 1, 1977?
Answer: No.
Question: When might all publicly
owned treatment works achieve secondary
treatment?
Answer: Achievement is dependent
primarily on Federal funding.* For example,
it could be achieved in 11 years with 75
percent Federal funding of all eligible
construction categories except control and
treatment of separate storm sewer flows with
a total Federal outlay of $118.5 billion,
provided Federal appropriations and com-
mitments are made ranging from $2.6 billion
the first year to $15.6 billion in the last
two of the eleven years. This pattern would
require radically accelerated processing of
all phases of grant administration and
treatment plant construction. (Inflation
could increase the total to $184.4 billion.)
Achievement of some eligible categories
could be realized earlier depending upon
selective Federal funding.
Industries - 1977
Question: Is "best practicable control
technology currently available" as defined
for industrial dischargers technologically
achievable?
Answer: Generally, yes, with the
exception of short term limits in some cases
and waste constituents or mixed wastewater
streams in others.
Question: Will all industrial dis-
chargers achieve best practicable control
technology currently available by July 1,
1977?
Answer: No.
Question: When might all industrial
dischargers achieve best practicable control
technology currently available?
Answer: Perhaps by 1980; industries
appear to be moving to achieve the 1977 re-
quirement at a rate that will assure achieve-
ment earlier than publicly owned treatment
works will achieve their 1977 requirements.
*H.R. 9560, Sec. 9, would allow time exten-
sion on a case-by-case basis but in no event
later than July 1, 1982.
657
-------
Capital Costs for 1977
Amount
Technology Costs (Billions, 1975 $)
Iron & steel
Organic & miscellaneous
chemicals
Inorganic chemicals
Petroleum refining
Pulp & paper
Metal finishing
Fruits and vegetables
Plastics & synthetics
Textiles
Steam electric power*
Feedlots**
All other industry***
$2.91
4.29
0.52
1.05
2.64
14.14
0.44
0.16
0.54
74*
21**
11.67***
Capital Expenditures for 1977*
Economic Impact Amount
Expenditures* (Billions, 1975)
TOTAL $44.31
Iron & steel
Organic and miscellaneous
chemicals**
Inorganic chemicals
Petroleum refining
Pulp & paper
Metal finishing
Fruits and vegetables
Plastics and synthetics
Textiles**
Steam electric power***
Feedlots****
All other industry
TOTAL
$2.08
4.29**
0.81
0.83
2.33
9.13
0.16
0.21
0.54**
4.09***
0.80
11.28
$36.5
*Includes growth to 1977-
**Includes growth to 1977 and assumes
coverage of all feedlots. Estimated
costs for EPA's most recent proposal
(November 1975) would be $0.11 billion.
***See Table p. 10 for listing.
B. Economic Effects - 1977
Publicly Owned Treatment Works
Categories
Amount
(Billions,
1975 $)
10.8
I. Secondary treatment
II. Treatment more
stringent than
secondary 24.8
IIIA Correction (infil-
tration/inflow) 6.9
11 IB Sewer rehabilitation 9.5
IVA Collector sewers 13.0
IVB Interceptor sewers 13.5
Minimum
V. Combined
sewers $5.4
Calendar
Year
Achieved
1980
1980
1985
1985
1985
1980
Maximum
SUBTOTAL $83.9
VI. Control of
storm-
waters 158.0
TOTAL $241.9
79.6 88.4 1985
$158.1 $166.9
199.0 427.0
$357.1 $593.9
*For plants in place as of June 1973;
no growth from that date is included.
**Does not have adjustments for closures.
***Inc1udes all costs for existing plants
not entitled to exemption to meet
thermal requirements which become effec-
tive July 1, 1983.
****Includes all categories of feedlots
with a limited number covered in each
category.
658
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C. Environmental Effects - 1977
Question: How far will the uniform
application of BPT to industrial dis-
chargers and secondary treatment to publicly
owned treatment works go toward achievement
of the interim goal, a water quality
"wherever attainable" "which provides for
the protection and propagation of fish,
shellfish, and wildlife and provides for
recreation in and on the water ... by
July 1, 1983"?
Answer: Based on the analysis of the
Commission's 41 environmental sites,
application of the 1977 requirements will
restore a large portion of the nation's
presently polluted waters to a level of
physical and chemical quality sufficient
to provide for achievement of the interim
goal. The chief exceptions are caused by
toxics, pulse loads discharged from
point and nonpoint sources during and fol-
lowing storms and delays in actual achieve-
ment of the 1977 requirements. Maintaining
that level of quality with continued growth
will depend upon timely and effective
compliance with outstanding permits and the
effective application of more stringent
limitations that may become necessary
following adoption of water quality stand-
ards where the volume of pollutant dis-
charges begins to produce lower water
quality.
DISSOLVED OXYGEN IMPROVEMENT
UNDER 4 LEVELS OF POLLUTION CONTROL ABATEMENT
DO Level
Milligrams per liter
EDO
Minimum criterion during
; / s
seasonal low flow
= anaerobic.
10% 20% 30% 40%
Percent of area with DO equal to or less than level shown
50%
500 1000 1500 2000 2300
River miles with DO equal to or less than level shown
*Based on projected improvements at 21 sites covering
a total of 4600 river miles during seasonal low flow
conditions.
Source: Natl. Commission on Water Quality compiled
from environmental contractor reports.
February 1976
KEY ABATEMENT LEVELS
EOD
1983
1977 T
1977 A
Present ——
See Table IV-3
for explanation
of abatement
levels
659
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II. "Technological aspects of achieving";
"economic, social and environmental
effects_of achieving or not achieving,
the effluent limitations and goals
set forth for 1983. ..."
A. Technological Aspects - 1983
Publicly Owned Treatment Works - 1983
Question: Does technology adequate to
achieve "best practicable waste treatment
technology over the life of the works"
for publicly owned treatment works exist?
Answer: Yes, since as defined by EPA
this technology is virtually the same as
that described by EPA for 1977.
Question: Will all publicly owned
treatment works achieve the "best practi-
cable waste treatment technology over the
life of the works" by July 1983?
Answer: No. The primary reasons for
not achieving this requirement by the
scheduled date is an inadequate rate of
Federal funding, slow obligations of
existing funds and the time it takes for
construction of treatment works.
Question: When might all publicly
owned treatment works achieve best practi-
cable waste treatment technology over the
1ife of the works?
Answer: Depends primarily on level of
Federal funding. Could be achieved in
eleven years, so long as there is little
technological difference between the 1977
and 1983 requirements and an adequate level
of Federal funding, commitment of the funds
and construction of plants is maintained.
Industries - 1983
Question: Is defined "best available
technology economically achievable" for
industrial dischargers technologically
attainable?
Answer: Generally, yes, with the
exception of short term (24-hour) limita-
tions in some cases and those instances
where application of technologies must be
transferred from one industry to another
or have not been adequately demonstrated.
Question: Can industrial dischargers
attain best available technology economical-
ly achievable by July 1, 1983?
Answer: Depends upon date the 1977
requirements are actually met and resolution
of challenges to some effluent limitations
and permits.
Question: Should the deadline for
industry to achieve "best available techno-
logy economically achievable" remain
July 1, 1983?
Answer: No, and a "mid-course cor-
rection" appears indicated.
Added Costs for 1983 Requirements
Technology Costs
Iron & steel
Organic & misc. chemicals
Inorganic Chemicals
Petroleum refining
Pulp & paper
Metal finishing
Fruits & vegetables
Plastics & synthetics
Textiles
Steam electric power*
Feedlots**
All other industry
TOTAL
Amount
(Billions 1975 $)
$0.95
3.64
0.25
1.18
0.80
14.09
0.16
0.29
0.30 Maximum
2.03*
0.49**
6.38
T7T96
$30.56 $36.49
*Includes growth to 1983. Range depends on
assumed exemptions.
**Includes growth to 1983. Estimated costs
for EPA's most recent proposal (November,
1975) would be $0.04 billion.
660
-------
B. Economic Effects - 1983
Added Expenditures for 1983 Requirements
Economic Impact
Expenditures
Iron & steel
Organic & miscellaneous chemicals
Inorganic chemicals
Petroleum refining
Pulp & paper
Metal finishing
Fruits & vegetables
Plastics & synthetics
Textiles
Steam electric power
Feedlots
All other industry
TOTAL
Existing Plants
Amount
(Billions 1974 $)
New Sources
1973 to 1983
Amount
(Billions 1975 $)
$ .65
2.25
.35
.29
.73
3.97**
.05
.09
.28
.99
.23
10.11
$19.90
*Does not have adjustment for closures.
**Excludes captive shops included in
machinery and mechanical products, $8.30
billion, under all other industry.
***Includes all categories of feedlots with
a limited number covered in each category.
661
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Table III.P.L
I NDJJ S T R Y
Preliminary Economic Impact Expenditure Estimate
(Millions of 1975 dollars)
Indepth
Fruits & Vegetables
Inorganic
Organic
Misc. Chemicals
Iron and Steel
Metal Finishing-Job
Captive
Petrol. Refining
Plastics & Synthetics
Pulp and Paper
Steam Electric
Textiles
Other
Ore Mining & Dressing
Coal Mining
Petrol. & Gas Ext.
Mineral Mining & Proc.
Meat Products & Rendering
Dairy Products
Grain Mills
Cane Sugar Processing
Beet Sugar
Canned & Preserved Seafood
Misc. Food & Beverages
Timber Products
Furniture & Fixtures
Bldg. Paper & Board
Paint & Ink
Soap & Detergent
Phosphate Mfg.
Fertilizer Mfg.
Paving & Roofing
Rubber Processing
Leather Tanning
Glass Mfg.
Cement Mfg.
Concrete, Gypsum, Plaster
Asbestos
Insult. Fiber
Ferroalloy Mfg.
Nonferrous Metals
^Machinery & Mech. Prod.
Transportation Ind.
Water Supply
Auto & Other Laundries
Foundries
(continued)
BPT
(1977)
Annual
Capital O&M
155
805
3328
965
2080
1715
7418
829
209
2331
4089
537
24461
14
178
487
163
261
328
2275
142
33
117
989
88
5075
BAT
Capital
111
261
2990
653
546
780
7468
1184
286
757
1275
300
16611
(1983)
Annual
O&M
12
140
2242
228
203
168
1365
429
29
36
16
29
4897
19.75-83
NSPS
Capital
47
351
1873
380
647
3967
a
294
91
734
900
275
9559
611
1690
234
728
148
198
56
153
90
55
--
14
7
120
23
8
108
73
7
221
77
35
34
100
4
13
48
40
3900
866
1222
18
182
25
95
18
72
20
14
4
17
17
14
0
1
3
12
23
1
13
47
7
18
20
4
4
26
1
5
16
21
293
88
156
3
26
0
0
1069
0
179
66
9
165
69
105
5
25
0
0
0
1
26
68
4
48
39
57
9
0
9
0
10
31
3900
143
104
21
0
0
0
61
0
16
5
1
13
5
5
1
8
0
0
0
1
3
22
1
12
8
9
1
0
4
0
4
7
293
39
3
1
0
146
0
266
496
64
0
0
8
2
38
4
33
2
13
2
2
46
50
1
299
13
26
12
36
3
3
11
39
8295
137
28
8
0
662
-------
Table III.P.L (continued
INDUSTRY
Preliminary Economic Impact Expenditure Estimate
(Millions of 1975 dollars)
Other
Fish Hatcheries
Structural Clay
Pottery
Steam Supply
Nonferrous Mills
Feedlots:
Beef
Hog
Dairy
All Other Industries
In-depth Industries
TOTAL 36642 6234 22992 5423 19903
*Excludes Captive Metal Finishing
a Included in Machinery and Mechanical Products
b Includes all categories of feedlots with a limited number
covered in each category.
National Commission on Water Quality
October 2, 1975
BPT
(1977)
Annual
Capital O&M
5
3
0
195
185
445
265
12181
24461
1
1
0
18
13
22
20
1159
5075
BAT
Capital
--
4
0
—
42
117
56
6381
16611
(1983)
Annual
O&M
--
3
0
—
0
0
0
526
4897
1975-83
NSPS
Capital
2
1
--
33
225b
--
--
10344
9559
663
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C. Social Effects and Benefits -
1977 and 1983
Question: Who is likely to bear the
adverse social impacts from the achievement
of the water quality requirements and goals?
Answer: Adverse impacts will fall most
heavily on the employees and owners (either
individual or corporate) of those industrial
plants closed as a result of the implementa-
tion of the 1977 and 1983 effluent limita-
tions. Generally, small older businesses
will be adversely affected. Employment
losses from plant closures, both direct
and indirect, could amount to over one-half
million jobs with full implementation of
BPT and BAT limitations. Other categories
adversely impacted will be the moderate-
income family seeking to enter the housing
market for the first time, the low-income
resident who will bear a higher relative
cost of the local share of financing pol-
lution control facilities relative to his
income as a result of the shift from pro-
perty taxes to user fees.
Question: How many jobs will be
created by the implementation of P.L.
92-500? What kind of jobs will they be and
how well distributed geographically and
demographically?
Answer: The major direct labor re-
quirement will be for construction workers
to build the plants and facilities. Heav-
iest impacts will be in the area of publicly
owned treatment systems and sewers, where
employment will reach a peak in 1977 of
296,000 new jobs and remain at over 100,000
through 1983*. Overall, between 1975 and
1985, implementation of the Act will create
a total of nearly one and a half million
man-years of work in the construction of
publicly owned waste treatment facilities.
Question: Who benefits? Are there
identifiable publics that receive the
benefits derived from improved water
quality?
^Assumes BPT met by 1977 with expenditures
over three years, and BAT met by 1983 with
expenditures spread over six years; and
$60.9 billion for publicly owned treatment
works spread over eleven years.
Answer: Sports fishermen, commercial
fishermen, seafood canners and processors
and those commercially associated with
water-based recreational pursuits -- especi-
ally recreational boating -- will be major
beneficiaries of the Act. Property owners,
too, of riverside and shoreline properties
will enjoy not only the benefits of improved
water quality adjacent to their property, but
also the increased value of the property as
well.
Question: Are the benefits from the
achievement of the 1983 interim water
quality goal quantifiable?
Answer: Yes. Improved water quality will
provide the American public with greatly ex-
panded opportunities for water-based recrea-
tion, sports fishing and the commercial
harvesting of fish and shellfish. Each of
these activities will result in directly
measurable benefits to individuals, segments
of society and to the economy in general.
There will be additional unquantifiable
benefits resulting from aesthetic changes in
water bodies and water-related activities.
Question: Economically, what will
these benefits amount to?
Answer: All quantified benefits, trans-
lated into dollar gains, may increase from an
estimated annual rate of $3.4 billion in 1980,
to $5.2 billion in 1985, and $7.8 billion in
the year 2000, assuming gradual improvement
from the present to 1985 with increases in
benefits thereafter resulting solely from
population and economic growth.
Question: Are these short-term benefits?
Answer: No. Assuming the maintenance
of the water quality, these gains will con-
tinue to accrue into the future. For swim-
ming alone, the cumulative benefits from
1985 to the year 2000 could reach between
$16 and $17 billion, and annual quantifi-
able benefits for all activities could
reach $6.4 billion by the year 2000.
Question: Are there unquantifiable
benefit associated with the achievement of
the 1983 interim water quality goal?
664
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Answer: Yes, two important kinds:
(1) those not fully identified yet, such as
health effects, where quantification now is
impossible; and (2) those associated with
non-contact related experiences.
II. D. Environmental Effects - 1983
Question: Do incremental improvements
in water quality characteristics associa-
ted with achievement of the 1983 effluent
limitations contribute significantly to
the realization of the 1983 goal?
Answer: In most cases, the gains are
projected to be less than those indicated
for achievement of the 1977 requirements.
III. Technological Aspects and Economic
Effects of 1977 and 1983 Requirements
Applied to Agriculture
Agriculture - 1977 and 1983
Question: Are agricultural point
sources of pollutants amenable to the
technological concepts of BPT and BAT?
Answer: Some are, such as feedlots.
Others, such as irrigation return flows,
present unique and widely variable problems
when attempting to apply effluent limita-
tions requirements of P.L. 92-500.
Question: What is being done to
implement BPT for irrigation return flows?
Answer: Since EPA has defined the
1977 requirement as monitoring the quantity
and quality of intake water supply and
irrigation return flows, BPT as so far
defined, is technologically achievable.
Complex and widely varying systems by which
excess water applied for irrigation reaches
surface and ground waters in the vicinity
of its application, do present even monitor-
ing problems, however. Known control tech-
nologies currently available are not so
well developed as to assure their universal
practicable application with predictable
results.
Question: Is "best available techno-
logy economically achievable" to control
pollutants in irrigation return flows
technologically attainable by July 1, 1983?
Answer: No, simply because no univers-
ally applicable or effective technology has
been developed which can be applied with
reasonably predictable results for all
geographic areas.
Question: Should statutory provisions
intended to control pollution from irrigation
return flows remain a part of P.L. 92-500?
Answer: Yes, but they should be so
formulated and designed as to recognize the
variety of polluting effects, the unique
institutional structure of irrigated agri-
culture, the wide geographical differences
in irrigation objectives and practices and
the state-of-the-art for control practices
and measures for reducing pollutants from
irrigated agriculture.
IV. Institutional Factors Influencing
"Technological Aspects of Achieving"
arid "Economic, Social, and Environ-
mental Effects of Achieving or Not
Achieving, the Effluent Limitations
and Goals Set Forth for 1983 "
Institutional Factors 1977 and 1983
Question: How has the response of the
national institutional structure for water
pollution control -- Federal, State, inter-
state, regional and local governments,
industrial and agricultural dischargers and
all interested groups -- affected achieving
or not achieving by the stated deadlines
all that is required to meet the require-
ments and goals of P.L. 92-500?
Answer: Individually and collectively,
their response has contributed to the time
required to achieve results under P.L. 92-
500. Unfortunately, the interrelationships
have too often been adversary rather than
cooperative in nature.
Question: What are the implications of
the resultant delays in meeting deadlines
or implementing various statutory directives?
Answer: The obvious implication is
that the time schedule for accomplishment
of some requirements and goals of the Act
is out of phase. The first major deadline
-- installation by dischargers of Phase I
wastewater treatment technologies by
July 1, 1977 -- will not be met by all
665
-------
dischargers, and the series of delays
which have occurred within the institu-
tional structure and the slow flow of grant
funds share major responsibility. This
fact requires consideration of alteration
in the present time schedule for accomplish-
ment to coincide more closely with the
realities of current circumstances and
available funding as well as the limitations
inherent in the intergovernmental process
and the interactions between these
governments and the various affected and
participating "publics".
Question: Where in the program struc-
ture are the delays most seriously mani-
fested, and what do they reveal about the
fundamental implementation strategy of the
Act?
Answer: The strategy of the Act is
predicated on the proposition that 75
percent Federal construction grant as-
sistance for publicly owned treatment works,
coupled with strong centralized national
initiatives for regulation and enforcement
structured within a framework of compre-
hensive state and local planning, will
produce the most expeditious, effective
and sensitive application of resources and
manpower to the accomplishment of national
water quality objectives. In the first
three years a divergence has evolved
between the proposition and its realiza-
tion. Delays in issuance of guidelines,
effluent limitations, and regulations,
delays in the obligation and outlay of
Federal funds for construction grants,
delays and variations in the issuance of
the NPDES permits for municipal, industrial
and agricultural dischargers and the fact
that mandated planning requirements are
seriously out of synchronization with the
construction grants and permit phases, all
contribute to uncertainty as to the validity
of the essential proposition. Experience
with implementation to date can neither
effectively discredit nor irrefutably
sustain the proposition. Experience can,
however, identify the points in the imple-
mentation process where the delays have
been most pronounced and make some observa-
tions, based on performance thus far, about
the basic structure of institutional co-
operation vital to the Act's fair and ef-
fective implementation.
A. Regulation
Question: Has implementation progres-
sed sufficiently to identify any basic
problems with the regulatory strategy con-
templated in P.L. 92-500?
Answer: While there are still a number
of uncertainties about the implementation
of the regulatory scheme, the conduct of
two activities in the regulatory strategy
can jeopardize the effective implementation
of the Act. One is the development and
promulgation of effluent limitations which
are being aggressively contested by industry
in over 250 legal challenges. The other is
the capability of the Federal, state and
local regulatory and administrative agencies
to develop useful information systems for
monitoring and reporting compliance with the
Act's various program components.
B. Financing
Question: Has the flow of Federal
construction grant funds to the states for
publicly owned treatment works impacted the
timely achievement of the 1983 requirements
and the interim goal?
Answer: Yes.
C. Planning
Question: Has implementation of the
planning provisions of the Act progressed
commensurate with the planning policy
objectives articulated in Sec. 101(a)(5) --
"that areawide waste treatment management
planning processes be developed and imple-
mented to assure adequate control of sources
of pollutants in each state"?
Answer: No. The planning process is
already out of sequence with the imple-
mentation strategy.
D. Public Participation
Question: Has the experience with
public participation in water pollution
control programs differed significantly
under P.L. 92-500 from prior experience?
Answer: No. Even though the Act
mandated an unprecedented public role, there
is no empirical evidence to suggest that the
actual influence of the citizen on the
decision-making process has effectively
increased.
666
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V. What Vim Remain to be Done After 1983
Elimination of the Discharge of
Pollutants - the 1985 Goal
Question: Assuming achievement of the
1977 and 1983 requirements for publicly
owned treatment works and agricultural and
industrial dischargers at some future date
later than 1983, what major pollutant
sources will continue to prevent realization
of the interim and ultimate goals?
Answer: Any point source (such as urban
runoff in separate storm sewers) not
adequately controlled with the 1977 and
1983 requirements or any nonpoint source
(such as urban runoff from other than
combined sanitary and storm and separate
storm sewers and agricultural or general
land runoff) contributing pollutants to the
nation's waters can prevent achievement of
the water quality goals of the Act. The
effect of these source contributions in some
site specific areas of the country will
prevent achievement of the water quality
goals of the Act and may, in some cases,
overwhelm improvements from point source
control. To the extent that publicly owned
treatment works, industrial and agricultural
dischargers have not achieved elimination of
the discharge of pollutants, they, too,
would be major contributors.
Question: Are there technologies avail-
able now, or that might reasonably be expec-
ted to become available within the next 10
years, that could achieve the elimination
of "the discharge of pollutants into the
navigable waters"?
Answer: Yes. However, in most cases the
costs of these technologies are such that,
however the technologies might be applied to
point source discharges, their installation
would be prohibitively expensive, and the
economic and social effect would be too
severe to be absorbed within the foreseeable
future; further, predictable environmental
effects, using present analytical techniques
and methodologies, would appear to be
minimal, particularly in the absence of
adequate control of nonpoint sources of
pollutants in some places.
Question: Does the goal of the elimi-
nation of "the discharge of pollutants into
the navigable waters" have value as a guide
to policymakers?
Answer: Yes. Wastes generated by pro-
jected population increases and continued
economic growth, if discharged to the
nation's waters, can soon minimize the
effect of improvements in receiving water
quality realized through achievement of the
1977 and 1983 requirements of the Act applied
to point source discharges. If new sources
of pollutants -- new industrial plants,
agricultural activities and increased dis-
charges from publicly owned treatment works
-- install "the best available demonstrated
control technology, processes, operating
methods or other alternatives, including,
where practicable, a standard permitting
no discharge of pollutants" [Sec 306(a)(l)],
and if existing water quality standards are
regularly reviewed and appropriate waste
load allocations timely made, this action
may assure that growth does not negate the
improvements achieved by point source
effluent limitations as the program envi-
sioned by P.L. 92-500 is implemented.
Question: Is progress being made to-
ward the "objective of this act ... to
restore and maintain the chemical, physical,
and biological integrity of the nation's
waters"?
Answer: Yes, although progress to date
attributable to P.L. 92-500 is minimal, since
results from its implementation are only now
beginning to be realized.
Question: Can this "objective" serve as
a guide to policy-makers for their actions?
Answer: Not with much certainty or
specificity. Even the experts cannot agree
upon a full statement of the objective's
meaning. "Restore" obviously means returning
to some prior condition; restoring "physical"
integrity could mean eliminating man-made
changes in the nation's waterways so that
sediment loads and temperatures would be as
they were before man's perturbations of the
land; restoring "chemical" and "biological"
integrity would require knowing these con-
ditions of the nation's waters at some
historical point in time with a degree of
accuracy not possible from existing historical
data. Man has consistently adjusted, or
attempted to alter, the "biology" of the
667
-------
nation's waters to suit his perceived
needs. These adjustments or alterations
would have to be eliminated in any literal
application of the objective -- often to
man's discomfort, if not to the detriment
of his well-being or health.
668
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/9-76-023
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
PROCEEDINGS, FOURTH UNITED STATES/JAPAN CONFERENCE
ON SEWAGE TREATMENT TECHNOLOGY
5. REPORT DATE
October 1976 (issuing date)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
U. S. Environmental Protection Agency*
10. PROGRAM ELEMENT NO.
IRW 103
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
U. S. Environmental Protection Agency* - Cin., OH
13. TYPE OF REPORT AND PERIOD COVERED
Proceedings - Oct. 23-28. 197
14. SPONSORING AGENCY CODE
EPA/600/14
15.SUPPLEMENTARY NOTES*Symposium sponsored by Office of Int 1 Activities, Office of Water
& Hazardous Materials (Wash.,D.C. 20460), & Office of Research & Development (Cinti.OH
45268 & Wash.,D.C. 20460). This volume prepared & published by Office of Research &
16. ABSTRACT
Development, Cincinnati, Ohio 45268.
As part of joint interests in environmental matters between the United States
and Japan a Conference on Sewage Treatment Technology is held at intervals of about
18 months. This publication contains papers from the Japanese group and from the
American side that were presented at the Fourth Conference. Subject matter covered
includes sludge treatment and disposal, automation and instrumentation, advanced
waste treatment, planning and management of wastewaters, storm and combined overflows,
and industrial waste treatment. The publication is unique in that it presents, in
English, comprehensive information on wastewater treatment and research being
conducted in Japan.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
Sewage treatment, Sludge disposal,
Industrial waste treatment,
Waste disposal
Water pollution control
13B
8. DISTRIBUTION STATEMENT
To Public
19. SECURITY CLASS (This Report)'
unclassified
21. NO. OF PAGES
681
20. SECURITY CLASS (This page}
unclassified
22. PRICE
EPA Form 2220-1 (9-73)
669
*USGPO: 1977-757-056/5496 Region 5-1
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