EPA- 600/9-76-021
POLISH /U.S.
SYMPOSIUM
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1O -12,1976
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EPA-600/9-76-021
POLISH/Ui
SYMPOSIUM
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flJUDGS DISPOWL
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DISCLAIMER
This report has been reviewed by the U.S. Environmental Pro-
tection Agency and approved for publication. Mention of trade
names or commercial products does not constitute endorsement or
recommendation for use.
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FOREWORD
Municipal and industrial demands on water resources in the
Polish Peoples Republic and the United States place increasing
emphasis on the need for water pollution and abatement control
research. These demands are recognized as important national
concerns in both countries, and increased research efforts are being•
placed on wastewater treatment, sludge utilization, and renovated
water use. Since 1972, the U.S. Environmental Protection Agency
has conducted an extensive research program with the Polish
Ministry of Administration, Local Economy and Environmental
Protection and with the Ministry of Agriculture. The Symposium
reported here highlighted the importance of cooperative inter-
national projects which are a part of each nation’s research objec-
tives; it serves to focus worldwide attention on a persistent and
difficult environmental concern.
A forum for technical exchange among the Polish and American
scientists and engineers engaged in cooperative projects was pro-
vided by the joint Symposium on Wastewater Treatment and
Sludge Disposal held in Cincinnati, Ohio, February 10-12, 1976. In
addition to the EPA and Polish representatives at the Symposium,
academic and industrial scientists participated from the University
of Cincinnati, Carnegie-Mellon University, Clemson University,
and the American Iron and Steel Institute. Discussions focused on
seven water-related projects, valued at approximately $1.4 million,
that are being conducted in Poland under the Special Foreign
Currency Program. These projects include studies of industrial
wastewater from steel, textile, and tannery industries; biological
and physical/chemical wastewater treatment technology; sludge
utilization; and wastewater reuse.
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CONTENTS
Foreword iii
Agenda of Symposium vi
Delegates to Symposium Viii
Summary and Recommendations 1
The Research Works on Sewage
Treatment in Poland, Stanislaw Nawara 2
Trends in Sludge Treatment and Disposal
Practices in the United States, Dr. Joseph B. Farrell . I I
Composting of Sewage Sludge
and Solid Waste Matter, Dr. Jozef Cebula 18
Effect of Water Work’s Sludge
on Wastewater Treatment, Dr. Janv$z Zalcrzewski 33
Physical-Chemical Treatment of Combined
Steel/Municipal Wastewater, Dr. Jan Suschka 41
Comparison of Alternative Strategies for Coke Plant
Wastewater Disposal, Dir. Robert W. Dunlap and
Dr.Francis Clay McMichael fl... 48
Tannery Waste Management, Dr. I . Dav id Eye 65
Developing Treatment for
TextileWastes,Dr.JanSuschka .77
Textile Wastewater Treatment Methods
SuitableforRecovery, Dr. John f t. Porter . 87
Removal of Refractory Substances from Textile
Wastewater, Dr. Jerzy KurHel and Thomas N. Sargent 99
The EPA Research and Development Studies
on Textile Wastewàter, Thomas N. Sargent . 109
Testing of Biodgradability and Toxicity of Organic
Compounds in Industrial Waste Waters, Dr. Jan ft. Dojlido . .112
Concepts, Criteria and Measurements
ofBiodegradabiity,Dr.RobertL .BuflCh 132
Renovated Water from Municipal Sewage
Treatment Plants, Dr. Apolinary L. Kowal 141
Wastewater Reuse Practice in the
UnitedStates,Dr. Carl A.Brunner . 151
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AGENDA OF’ SYMPOSIUM
Tuesday, February 10— A .M.
Moderator: Francis M. Middleton
9:00 A ,M. Welcome to Cincinnati Francis M. Middleton
Opening Remarks Dr. Thomas Murphy
Thomas J. Lepine
Stanislaw Nawara
9:30 AM. The Research Works on Sewage
Treatment in Poland Stanislaw Nawara
10:00 AM. Trends in Sludge Treatment
and Disposal Practices
in the United States Dr. Joseph B. Farrell
10:30 AM. Break
10:45 A.M. Composting of Sewage Sludge
and Solid Waste Matter Dr. Jozef Cebula
11:15 A.M. Effects of Water Works Sludge
on Wastewater Treatment Dr. Janusz Zakrzewski
11:45 A.M. Discussion
12:00 Noon Lunch
Tuesday, February 10— P.M.
Moderator: John J. Convery
1:30 P.M. Physical-Chemical Treatment
of Combined Steel/Municipal
Wastewater Dr. Jan Suschka
2:00 P.M. Comparison of Alternative
Strategies for Coke Plant Dr. Robert W. Dunlap
Wastewater Disposal Dr. Francis C McMichael
2:30 P.M. Break
2:45 P.M. Tannery Waste Management Dr. J. David Eye
3:15 P.M. Discussion of Afternoon Papers
Discussion Leader: Dr. Herbert S. Skovronek
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Wednesday, February 11 — A.M.
Moderator: Dr. Eugene E. Berkau
9:00 A.M. Developing Treatment for
Textile Wastes Dr. Jan Suschka
9:30 A.M. Textile Wastewater Treatment
Methods Suitable for
Recovery Dr. John J. Porter
10:00 A.M. Break
10:15 kM. Removal of Refractory Sub-
stances from Textile
Wastewater Dr. Jerzy Kurbiel
10:45 A.M. The EPA Research and
Development Studies on
Textile Wastewater Thomas N. Sargent
11:15 A.M. Discussion of Morning Papers
Discussion Leader: Thomas N. Sargent
11:45 A.M. Lunch
Wednesday, February 11 — P.M.
Moderator: Ms. Margaret J. Stasikowski
1:00 P.M. Testing of Biodegradability
and Toxicity of Organic
Compounds In Industrial
Waste Waters Dr. Jan R. DojIldo
1:30 P.M. Concept, Criteria and Measure-
ments of Biodegradability Dr. Robert L. Bunch
2:00 P.M. Break
2:15 P.M. Renovated Water from Municipal
Sewage Treatment Plants Dr. Apolinary L. Kowal
2:45 P.M. Wastewater Reuse Practice
In the United States Dr. Carl A. Brunner
3:15 P.M. Discussion of Afternoon Papers
Discussion Leader: John N. English
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DELEGATES TO SYMPOSIUM
POLISH DELEGATION
Dr. Jozef Cebula,
Department of Wastewater Technology and Sludge Disposal,
The Ministry of Administration,
Local Economy and Environment Protection,
Warsaw, Poland
Dr. Jan R. Dojlido,
institute for Economy and Water Management,
Warsaw, Poland
Dr. Apolinary L. Kowal,
Institute of Environment Protection Engineering,
Wroclaw Technical University,
Wroclaw, Poland
Dr. Jerzy Kurbiel,
Institute for Economy and Water Management,
Krakow, Poland
Stanislaw Nawara,
The Ministry of Administration,
Local Economy and Environment Protection,
Warsaw, Poland
Dr. Jan Suschka,
Environmental Pollution Abatement Centre,
Katowice, Poland
Dr. Janusz Zakrzewski,
Institute for Municipal Economy,
Warsaw, Poland
vu ’
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UNITED STATES DELEGATION
Dr. Eugene E. Berkau,
Director, Industrial Pollution Control Division,
Industrial Environmental Research Laboratory,
U.S. Environmental Protection Agency,
Cincinnati, Ohio 45268
Dr. Carl A. Brunner,
Chief, Systems and Engineering Evaluation Branch,
Wastewater Research Division,
Municipal Environmental Research Laboratory,
U.S. Environmental Protection Agency,
Cincinnati, Ohio 45268
Dr. Robert L. Bunch,
Chief, Treatment Process Development Branch,
Wastewater Research Division,
Municipal Environmental Research Laboratory,
U.S. Environmental Protection Agency,
Cincinnati, Ohio 45268
Mr. John J. Convery,
Director, Wastewater Research Division,
Municipal Environmental Research Laboratory,
U.S. Environmental Protection Agency,
Cincinnati, Ohio 45268
*Dr. Robert W. Dunlap,
Professor of Engineering and Public Affairs,
Carnegie-Mellon University,
Pittsburgh, Pennsylvania 15213
Mr. John N. English,
Sanitary Engineer, Municipal Treatment and Reuse Section,
Systems and Engineering Evaluation Branch,
Wastewater Research Division,
Municipal Environmental Research Laboratory,
U.S. Environmental Protection Agency,
Cincinnati, Ohio 45268
Dr. J. David Eye,
Professor of Environmental Engineering,
University of Cincinnati,
Cincinnati, Ohio 45221
Dr. Joseph B. Farrell,
Chief, Ultimate Disposal Section,
Treatment Process Development Branch,
Wastewater Research Division,
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency,
Cincinnati, Ohio 45268
*Representjng The American Iron & Steel Institute
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Mr. Fitzhugh Green,
Associate Administrator,
Office of International Activities,
U.S. Environmental Protection Agency,
Washington, D. C. 20460
*Dr. Francis Clay McMichael,
Associate Professor of Civil Engineering and Public Affairs,
Carnegie-Mellon University,
Pittsburgh , Pennsylvania 15213
Mr. Francis M. Middleton,
Senior Science Advisor,
Municipal Environmental Research Laboratory,
U.S. Environmental Protection Agency,
Cincinnati, Ohio 45268
Dr. Thomas Murphy,
Deputy Assistant Administrator for Air, Land, and Water Use,
U.S. Environmental Protection Agency,
Washington, D. C. 20460
Dr. John J. Porter,
Professor, Textile Department,
Clemson University,
Clemson, South Carolina 29631
Mr. Thomas N. Sargent,
Chief, Food and Wood Products Branch,
Industrial Pollution Control Division,
Industrial Environmental Research Laboratory,
TJ;S. Environmental Protection Agency,
Cincinnati, Ohio 45268
Dr. Herbert S. Skovronek,
Environmental Engineer,
Organic Chemicals and Products Branch,
Industrial Pollution Control Division,
Industrial Environmental Research Laboratory,
U.S. Environmental Protection Agency,
Edison, New Jersey 08817
Ms. Margaret J. Stasikowski,
Environmentalist, Metals and Inorganic Chemicals Branch,
Industrial Pollution Control Division,
Industrial Environmental Research Laboratory,
U.S. Environmental Protection Agency,
Cincinnati, Ohio 45268
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U.S. PLANNING COMMITTEE
Mr. Thomas .1. Lepine,
Chief, Special Foreign Currency Branch,
Office of International Activities,
U.S. Environmental Protection Agency,
Washington, D. C. 20460
Dr. Donald T. Oakley,
International Technology Division,
Office of International Activities,
U.S. Environmental Protection Agency,
Washington, D. C. 20460
Mr. Gregory Ondich,
International Technology Division,
Office of International Activities,
U.S. Environmental Protection Agency,
Washington, D. C. 20460
Dr. Robert L. Bunch,
Chief, Treatment Process Development Branch,
Wastewater Research Division,
Municipal Environmental Research Laboratory,
U.S. Environmental Protection Agency,
Cincinnati, Ohio 45268
Mr. Robert N. Carr,
Acting Director, Support Services Office,
Office of Research and Development,
U.S. Environmental Protection Agency,
Cincinnati, Ohio 45268
Mr. Francis M. Middleton,
Senior Science Advisor,
Municipal Environmental Research Laboratory,
U.S. Environmental Protection Agency,
Cincinnati, Ohio 45268
Mrs. Helen I. Moore,
Municipal Environmental Research Laboratory,
U.S. Environmental Protection Agency,
Cincinnati, Ohio 45268
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SUMMARY AND RECOMMENDATIONS
Environmental protection and enhancement are necessary and
desirable goals for all nations. This Symposium on “Wastewater
Treatment and Sludge Disposal” was a part of a much wider effort
aimed toward environmental control. Wastewater treatment, both
domestic and industrial, and the disposal of sludges are significant
technical and economic problems in Poland and the United States.
The Symposium had significant impact on the joint Polish/U.S.
projects. The open discussion of the papers, the injection of new
ideas, and the demonstration of workable solutions to some prob-
lems will go far to ensure continued successful projects. Directions
for future research were gained from the Symposium. The work-
shop attitude that prevailed among the 25 participants permitted
intimate and fruitful discussion of the technical matter on both
sides. The participants maintained an awareness that implementa-
tion of research results and attention to the problems of compliance
are vital to ultimate environmental improvement.
The problems in both countries are similar. Water conservation
and reuse, conservation of energy in environmental matters, com-
bining sludge disposal techniques to gain some useful product or
for economy of disposal, careful attention to land use for receiving
wastewaters or sludges, disinfection techniques, the cross media
effects of treatment and disposal technology are some of the areas
of importance. Specific presentations in the Symposium dealt with
wastes from municipalities, textile industries, iron and steel plants,
water plants, and tanneries. Research results and needs on biode-
gradability were stressed. It was concluded that work in the two
countries should complement each other. Close interchanges of
information and experts between the countries aids this concept.
Some future topics for research were listed:
—Utilization of residue chars and other byproducts from the
conversion and processing of coal
—Study of effects of using effluents on sludges (especially from
older systems) on crops, soil, and groundwater quality
—Tertiary treatment of industrial wastewaters, including pulp
and paper
—Disinfection of effluents and renovated waters.
Consideration was given to holding a symposium in Poland re-
lating to mutual environmental interests of both countries. The
topic is yet to be determined.
Proceedings of this Symposium have been printed in both Polish
and English.
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THE RESEARCH WORKS
ON SEWAGE TREATMENT IN POLAND
Stanislaw Nawara
ABSTRACT
The rapidly accelerating social and economic development in
Poland requires adequate institutional arrangements and scientific
programs to deal with environmental protection. To solve the
many environmental problems, the Polish Parliament has organ-
ized a governmental unit in the form of Ministry of Adminis-
tration, Local Economy, and Environmental Protection.
Activities now encompass protection of the air, water, and soil
as well as noise prevention. Water protection has been organized
since 1954. The voivodship offices across the country have an
important role in water pollution control. Adequate laws, regula-
tions, and enforcement have been enacted to protect the waters
of Poland.
About 80% of the water pollution in Poland comes from 2,800
industries and 600 towns. The largest contributors are the chemi-
cal, mining, power, food, and wood industries. Presently, about
60% of all wastewaters are treated.
Research for water protection is coordinated by the Environ-
ment Development Institute (EDI) and specialized institutes in
individual ministries conduct the research projects. The EDI de-
termines the standards, water quality norms, water classification,
and anti-pollution programs. A plan has been made through 1985.
Present water quality improvement programs include 1. pro-
ducing water and wastewater treatment equipment, 2. optimizing
water reuse in industry, 3. encouraging the production of biode-
gradable detergents, pesticides, and other similar materials that
are biodegradable, and 4. improving treatment methods, instru-
mentation, and information. ParticuLar attention is being given to
treating wastewater from small towns and tourist facilities. Ad-
vanced treatment processes are also under study to achieve the
high quality water needed in some areas.
Protection of the Baltic Sea was agreed to in the 1974 Helsinki
Convention. Poland is taking steps to meet the requirements for
keeping the Baltic Sea clean.
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INTRODUCTION
In the period of accelerated social and economic development
of our country, the problems of environment protection have been
accepted as a particularly important domain which presses for
organizing adequate institutions, elaborating suitable forms of
activity, and shaping a proper social attitude to these problems.
To solve these problems, the Polish Parliament created a com-
petent organ of State Administration in the form of the Ministry
of Administration, Local Economy, and Environment Protection.
This Ministry includes activities concerning such problems as:
— waters and atmospheric air protection against pollutants,
— waste treatment,
— noise and vibration prevention,
— protection and recultivation of soils.
As the need arises and in view of their intensity, these activities
can be expanded to include other environmental problems.
Among these environmental problems, protecting surface waters
against pollution has received the most attention; in 1954 when
the State Inspection for Protection of Waters was created all
matters in this field were organized under this administrational
activity.
This step was necessary to secure the water economy balance
in the country.
The quality of our water is of fundamental importance in view
of the increasing need for an adequate supply of quality waters
requested by the population, industry, and agriculture because
our water resources are limited and unevenly distributed over the
country. The seasonal water quantity fluctuations are also of
importance.
ORGANIZATION OF STATE ADMINISTRATION
IN ENVIRONMENT PROTECTION
The water protection problems are centrally supervised and
implemented by the Department of Environment Protection in the
Ministry of Administration, Local Economy, and Environment
Protection. This Department is coordinating and directing the
entire activity in this range.
Across the country, the water protection problems against pol-
lutants are regulated and directed by competent divisions of voi-
vodship offices. These divisions are composed of research and
testing centers that direct such activities as laboratory tests on
the quality of waters and sewages.
THE LEGAL PRINCIPLES FOR PROTECTION
OF WATER AGAINST POLLUTION
The Water Act and executional decrees based on it determine
the legal principles for activities involved in protecting waters
against pollution and those governing the rights and duties of
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water users. These regulations specify, for instance, the admissible
pollution limits for water and the conditions under which sewage
and effluents have to be discharged to waters, deep soils, and urban
sewage facilities. At the same time, they specify the principles
of pecuniary penalties for noxious pollution of waters and how
these penalities are to be assessed.
According to the regulations, the waters are noxiously polluted
when some physical, chemical, biological, or other changes make
them unsuitable for use by the population or by the national
economy and when detrimental changes in the environment arise.
The enterprises and plants that drain their sewages into waters,
deep soils, or urban sewage facilities are obliged to build suitable
sewage purifying plants and to keep them running.
The newly built plants and factories and those that are being
enlarged are obliged to start operating such purifying facilities
when initiating their production process.
As for the already existing plants without suitable purifying
facilities, the Water Act specifies the final time after which they
have to be erected and commissioned.
A special water license, issued by a competent regional state
administration organization, must be obtained to discharge sewage
into waters, deep soils, or urban facilities.
Those who violate the regulations concerning sewage discharges
are punished.
The Water Act regulations have introduced the principle of pay-
ing for water extraction and for discharging sewages into waters
and deep soils. A base is also created at the same time for special
protection of some waters so that no sewages are allowed to be
discharged into them; the range and principles of such protection
are also defined.
SOURCES OF POLLUTANTS
The surface waters in Poland are polluted mainly by industrial
waste discharges and by urban sewage, essentially about 2,800
industrial plants and 600 towns have sewage facilities. The indus-
trial works and plants annually originate about 80% of the total
volume of all sewage and effluents and constitute the principal
area of activity for the environmental protection organizations.
The greatest share of water polluters are the towns and indus-
trial plants with the chemical, food, and wood processing indus-
tries, as well as those with mining and power.
About 60% of all sewages that need purification are being filtered
to various degrees of final effectiveness by existing purifying facili-
ties in the works and towns.
SCIENTIFIC RESEARCH AND TECHNICAL BASE
FOR WATER PROTECTION
The details of the scientific research concerned with protecting
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water against pollution are being managed by specialized institutes
of the individual ministries directing the industry and by the
Environment Development Institute (EDI), which coordinates en-
vironment protection research, as a whole, in Poland.
The coordinational activity of the EDI is concentrated mainly
on programs and plans of the individual scientific research units
concerned with protecting the environment.
The primary duties of the institutes of specialized branches in-
clude developments in the area of purification process technology
for pollutants from the individual industrial branches.
The EDI develops the national needs concerning such general
problems as determining standards, water quality norms, methods
of classifying and estimating water purity, and also the anti-pollu-
tion water programs.
Among the achievements concerned with improving the methods
and sewage purification facilities and with developing as well as
introducing new purification technologies, the following are sig-
nificant:
—improved methods and equipment for recovering phenols in
sewages and improved methods of biological and physico-
chemical purification of phenol4aden sewages, up to high
limits of purity,
—development and introduction of procedures for biological
purification of sewages and effluents resulting from the pro-
duction of cellulose sulphate,
—development of thermic and hydrothermic methods for
treating salinated waters from mines,
—development and introduction of procedures for purifying
dairy effluents in biological lagoons,
—development and introduction of procedures for eliminating
hydrogen sulphide from waters collecting in sulphur mines.
TRENDS OF FUTURE RESEARCH
The wide development of water protection research work and
the practical use of the positive results are guaranteed as a result
of our Government’s including water resources utilization and
development problems into the group of State’s problems to be
solved gradually by the year 1985.
In the water quality improvement program, which is already
accepted, the following research items are included:
—starting the production of test pilot equipment and facilities
for sewage treatment and purification,
—optimizing water and sewage economy in the industrial
works and enterprises (by applying the closed, no-sewage,
and low-water-level circulation systems in the production
process),
-developing process technology for producing biodegradable
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pesticides, detergents, and other chemical products used for
agriculture, industrial, and domestic purposes,
—developing highly effective technological processes for treat-
ing sewage and for neutralizing sewage sediments, for puri-
fying water, and for reusing water from sewage as well as
for desalting the water from mines,
—developing industrial methods of erecting sewage treatment
plants, water intakes, and purification and pump-over sta-
tions,
—developing and starting continuous data measuring, trans-
mitting, and processing equipment needed for the economy
as well as for control of the water purification and sewage
treatment stations,
—building a system of measuring and signalling apparatus for
weather forecasting service as well as for monitoring the
quality of surface water,
—organizing the information needs for the entire country con-
cerned with saving both the quantity and quality of water.
The above all-inclusive program will be determinative in plan-
ning the work to be implemented according to the nearest 5-year
plans by the individual branch ministries and by the E lM—as the
nation-wide coordinator of research in this area—as well as by the
technical base centers. Among these centers, a leader in the produc-
tion of water protection equipment is the Communal Economy
Technical Base Union in Poznán, being subordinated to the Minis-
try of Administration, Local Economy and Environment Protection.
The said Union is supervising the “PoWoGaz” Multiplant Enter-
prise, which includes the Communal Apparatuses and Equipment
Factories at Poznán, Pniewo, and Pila. Among other items, pro-
duction of a small “Biblok” type sewage treatment facility has
been commissioned already. Each of these facilities is intended for
complete biological treatment of sewage at an output of 100 to 800
m 3 /day. They can be utilized especially in small settlements,
schools, hospitals, hotels, motels, recreational centers and houses,
social facility objects for working teams in industry, and others.
Sewage is treated here according to the low-loaded active sedi-
ment method.
A further development of this production in Poland is connected
with the possibility of fulfilling the needs that follow from im-
plementing planned recreational and tourist facilities and from
the program of providing the small settlements and villages with
sewage facilities.
Moreover, the “PoWoGaz” is specializing in the production of:
—measuring and testing apparatuses and equipment for water
• purifiëation,
—measuring and testing apparatuses for sewage treatment
purposes,
—communal services fee meters and some other ones.
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REQUIREMENTS AND NEEDS IN SEWAGE TREATMENT
According to assumptions from prospective water protection
programs in Poland, repurifying wastewater to a state that fully
meets consumer requirements should be reached by approximately
1990. These, assumptions are based on knowing the tasks to be
carried out during the next 15 years. These tasks will be imple-
mented by:
—equipping all pollutant sources with suitably efficient sewage
treatment facilities, according to obligatory legal principles
and regulations,
—introducing an accurate water savings regime in industry,
—correctly using newly built sewage treatment plants.
To implement the above, many billions of zloties need to be
invested.
Of special importance is the problem of preparing highly effec-
tive, technological methodology that has already been confirmed
and proven in sewage treatment practice.
When the prognosis for water purity confronts the assumed
spacial and economic development of our country in the next 15
years, it can be stated that__especially in the case of some rivers
and some of their parts—achieving the required water purity may
be impossible with the use of conventional mechano-biological fa-
cilities—facilities that limit reduction of pollutants to about 90%.
Consequently, further development will have to consider using
physico-chemical processes and methods that ensure the possibility
of a high-level neutralization of the refractory substances, i.e.,
those that are processed with tertiary sewage treatment and those
in water reuse processes.
Such attitude is justified by the need to take into account, at
higher and higher process levels, such pollution factors as: biogenic
substances, surface active compounds, pesticides, fertilizers and
some other specific ones that after some time will become a limit-
ing factor in water utilization possibilities for the economy pur-
poses. Research institutions are developing adaptations of some
of the mentioned processes. Some methods have already been in-
troduced into the process technology, e.g., the distillation process
that the Chief Mining Institute used when developing the thermal
desalting method in the case of concentrated brines. This method
was first tested at a pilot scale in the Hard Coal Mine “Debieñsko”
in the experimental plant and, then, in the first newly built de-
salting plant with a capacity reaching about 270 tons of salt per
24 hr.
Experiments are also being carried out using the reverse osmosis
and electrodialysis processes to reduce the mean level of salt
waters.
Although a number of treatment plants based on the chemical
precipitation processes are already operating, they are not in a
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sufficient number to meet the country’s needs—especially where
the treated sewage is discharged into rivers or other open waters
used by the local population for a variety of purposes.
Applications of the sorption and ionic exchange processes are
also being developed.
Commitments flowing from the international cooperation and
especially from the cooperative role of Poland among the Baltic
Sea states have been implemented with the use of highly effective
methods.
The convention signed in Helsinki in 1974 protecting the Baltic
Sea environment aims to limit or to eliminate dumping several
pollutants into this sea because they are noxious substances, such
as heavy metals (among them, mercury and cadmium), phenols
and their derivatives, biogenic compounds, multi-ring aromatic
hydrocarbons, oils and petrochemical industry wastes, as well as
many other ones that must be eliminated from sewage at high
levels of effectiveness.
To ensure the implementation of the commitments following
from resolutions of this convention, especially those that
—eliminate or reduce considerably the direct or indirect
dumping into the sea of substances and materials listed in
the convention,
—equip ships with pollutant collectors or purifiers and ports
with equipment for receiving and liquidating these pollut-
ants,
—prepare the technological and organizational facilities neces-
sary to eliminate the effects of an accidental pollution of the
Baltic Sea,
—enlarge the scientific and research labors connected with
protecting the Baltic Sea against pollution,
—adapt the legal regulations to the requirements following
from this convention,
a Baltic Sea environmental protection program has been prepared
by the Governmental Ensemble; they determined the detailed
tasks within the above-stated range for the individual economic
and scientific organizations and institutions—tasks that must be
implemented within individual planning periods.
The scientific and research tasks for 1976-80 included in the
program consist of:
—methods and technology for measuring the pollution,
—specifying the degree the sea, including the bottom sedi-
ments, is polluted,
—specifying the degree the living organisms in the sea are
contaminated,
—determining the toxicity of chemical substances,
—determining the degree of self-purification of the Baltic Sea
waters, as well as
—methods of preventing sea water pollution.
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SUPPLEMENT
Some information on the results of the preliminary exploitation
in 1975 of the Biological Wastewater Treatment Plant in Czesto-
chowa (Poland). (Warsaw, February 1976.)
The Central Waste Water Treatment Plant in Czestochowa has
been constructed for combined treatment of industrial and com-
munity effluents. The stipulated flow capacity of the plant amounts
to 160,000 mVday. The present volume of wastewater amounts
to 80,000 m 3 /day.
Industrial effluents make up 50% of the total volume of waste-
water inflow. These effluents originate mainly from the following
industries: iron and steel, textile, paper, metallurgical, match-
making, chemical, dyeing, tanning, and food.
The load measured in kilograms per day of pollutants contained
in the wastewater inflow is: BOD, 31,500; suspended solids, 41,830;
grease, 6,500; su lphides, 95; vol . phenols, 2,400; cyanides, 60; chro-
mium, 2.5; rhodanates, 500; copper, 12; zinc, 6; and lead, 2.
When wastewater containing the above load of pollutants re-
ceives preliminary treatment, the quantity of sludge created aver-
ages 420 m 3 /day.
The sludge is digested by using an anaerobic mesophilic digestion
process in separate sludge digestion chambers. The quantity of
sewage gas averages 400 to 600 1/kg of dry organic substance.
According to data presented in technical publications, the quan-
tity of sewage gas received from sewage sludge amounts to 470 to
600 1/kg dry organic substance (Imhoff) and to 5 to 25 1/inh. day
(Cywinski et al., collected work).
According to the design of the Central Waste Water Treatment
Plant in Czestochowa, the excess activated sludge was to be
brought into the distribution chamber and then, together with
the raw sewage, be introduced into the primary settling tanks.
During the preliminary operation of the plant, it appeared, how-
ever, that large quantities of excess sludge flowed over the over-
falls of the settling tanks and got into the aeration tanks, where it
had a negative effect on the process.
Because of this, experiments on separate thickening of the
excess sludge in one of the primary settling tanks were carried
out with good results. The sludge settled very easily and had
good physical and chemical properties (pH, 7.1 to 7.3; organic
substance, 70 % to 73 %; water, 97 % to 98 %).
To compare, the characteristics of the raw sludge were: pH, 6.0
to 6.3; organic substance, 64 % to 68 %; water, 93 % to 97%.
To choose the most effective and economic system for aerating
wastewater, three kinds of aeration systems were investigated:
INKA, Kessener, and surface aerator (diam. 2,300 mm, model
produced in Poland by PoWoGaz).
The most useful for specific conditions at the Czestochowa treat-
9
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ment plant appeared to be the PoWoGaz surface aerator. Charac-
teristic of the turbine: AP, 2300m; immersion depth of the rotor
5 to 15 cm; OC kg 0 2 /h, 41 to 75; ED kg 0 2 /kWh, 1.6 to 1.7.
Treating the sludge in closed digestion chambers with the use
of the I-stage and I l-stage processes was investigated. From the
achieved results, the Il-stage system was recognized as being
more useful and effective. The degree of decomposition of organic
substances after the I-stage process was about 40 % and after the
Il-stage process was about 50 % to 58 %.
10
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TRENDS IN SLUDGE TREATMENT AND DISPOSAL
PRACTICES IN THE UNITED STATES
Joseph B. Farrell
ABSTRACT
Traditionally, wastewater sludge disposal practice has been de-
cided by location and local circumstance. An overriding considera-
tion has been cost. Ecological factors are now assuming their right-
ful influence. Serious attention to ecological considerations will
cause substantial change in the practice of sludge disposal.
Ocean disposal may be eliminated or, at the least, sludge will
be processed to remove harmful materials. New incineration fa-
cilities will be obliged to use sophisticated emission controls. If
sludge is applied to agricultural land, users must control pat ho-
genie organism and must limit the dose of certain metals to the
soil.
New sludge disposal methods being developed are composting
sludge with woodchips to make a high quality compost, coincinera-
tion with solid waste, pyrolysis, and copyrolysis with solid waste.
Disposal methods that conserve resources would see more ap-
plication if there were incentives to encourage their use. Similarly,
all means of disposal would see improvement if there were ade-
quate standards for measuring performance. Development of in-
centives and standards will improve quality of sludge disposal.
INTRO PUCTION
The amount of wastewater sludge produced in the United States
has naturally kept pace with the expanding practice of waste-
water treatment. However, when compared with the advances in
the technology of wastewater treatment, the technology of sludge
disposal has lagged behind. Except for the anaerobic digestion pro-
cess, processes and equipment were “borrowed” from existing
technology with little need for innovative thought. The major
concern at a wastewater treatment plant was the purification of
the wastewater stream; the concentrated wastes produced were
an unpleasant nuisance that bad to be rendered innocuous and
removed from the plant grounds. There were no standards of
quality or measures of performance for sludge comparable with
those developed for treated wastewater. The result was that the
overriding consideration was cost—cheapest was best. Fortunately,
11
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the situation is shifting rapidly, aided by an improved understand-
ing of what constitutes satisfactory disposal procedures.
There is no one best way to dispose of wastewater sludge. An
excellent procedure in one part of the country may be both too
costly and environmentally unacceptable in another. Numerous
factors, from geography to local air pollution codes, influence the
disposal choice. Maj or influencing factors and the factors they in-
fluence are presented in Table 1. Factors related to site and cir-
cumstances have had the greatest impact on choice of disposal
method in days past. It is only recently that ecological factors
have received the attention they deserve. For example, the prox-
imity of coastal cities to the ocean made ocean disposal their
obvious disposal choice. Today, potential ecological damage is
urging a reconsideration of this choice.
TABLE 1. INTERACTING INFLUENCES IN CHOICE OF
SLUDGE DISPOSAL METHOD
FACTORS INFLUENCED
PROCESS CONSIDERATIONS DISPOSAL CHOICE
All process steps such as stabilization Landfill
and dewatering pràcedures, even in- Incineration
cluding the choice of the wastewater Land utilization (cropland,
treatment process itself. reclamation)
Useful products (power,
fuel, activated carbon)
Ocean
INFLUENCING FACTORS
SITE AND CIRCUMSTANCE ECOLOGICAL
RELATED CONSIDERATION
Geography, geology, climate, condi- Health effects
tions at the site, sludge composition Air standards
(metals, pathogens, volatile solids), Water and groundwater
sludge quantity, sludge type, popula- standards
tion density, proportion and type of Food and crop effects
industry, other societal influences. Land use
In the last 10 years, the attitude of the Nation toward pollution
and quality of life has drastically changed, and this change has
been reflected in the laws of the land. Regulatory agencies at the
federal, state, and local level are carrying out the requirements
of the laws, and an irresistible movement towards an improved
environment has commenced. The law and the spirit of the people
have produced two major themes that have impacted the treat-
ment and disposal of sludges. The themes are “protection” and
“conservation.”
12
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PROTECTION AND CONSERVATION
Every disposal choice is touched by our need to protect our
ecosystem against possible harm. We are concerned about protect-
ing the ocean from irreversible change. The oceans are the ulti-
mate sink of wastes discharged by communities either directly
to the oceans or to rivers that flow into the oceans. Sludges con-
tain the concentrated wastes from wastewater. In many respects,
it is incongruous to separate wastewater into a relatively clean
water stream and a concentrated waste stream, and then put
them both into the ocean.
We need to protect our communities from the results of improper
incineration of sludge. Sludges often give off offensive odors, and
they contain higher concentrations of certain potentially hazard-
ous substances than other fuels. We must be sure to use suitable
procedures that control odors from incinerators and eliminate the
discharge of hazardous particulates and ashes.
The public expects protection against hazards from landfilling
of sludge. Sludge should not be placed where it can be washed
into streams by rainfall or where rainwater can saturate it, drain
through it, and contaminate groundwater. The sludge should not
be placed where innocent trespassers can be contaminated with it.
Protection against unwise use of sludge as a fertilizer is needed.
The metals in sludge can accumulate in certain crops and residual
pathogens in the sludge can contaminate low-growing crops; in-
discriminate use of sludge in gardens and truck farms presents a
hazard if the level of pathogens is not sufficiently reduced.
Conservation of resources must be considered along with pro-
tection from potential hazard. Wastewater sludge contains suf-
flëient nitrogen, phosphorus, and organic matter to make it an
extremely useful material in many agricultural applications. Ap-
plying it to the soil constructively utilizes organic matter that
would otherwise be wasted, and reduces the amount of nitrogen
and phosphorus fertilizers that have to be manufactured. Re-
sources needed to make these fertilizers are conserved, and the
total “earth burden” of nitrogen and phosphorus fertilizers is
reduced. It is evident from the foregoing that the use of sludge
on land presents hazards that must be measured against benefits,
and here the attitudes of protection and conservation come into
occasional conflict. Fortunately careful use of sludge for soil
amendment purposes can generally be carried out at loading
levels to the soil that are economically attractive to the disposer
and present no significant hazard to the environment or the
ultimate consumer of the crops.
Conservation urges us to reconsider the wasteful use of high-
grade fuels to incinerate sewage sludge. Alternative disposal prac-
tices are indicated, or else better means of converting the sludge
to an innocuous form should be found. The codisposal of sewage
13
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sludge by incineration or pyrolysis with solid waste offers poten-
tiaL The excess fuel value of the solid waste is more than suffi-
cient to make up for the low net fuel value of partially dewatered
sludge. The fuel shortage has made solid waste attractive for
other uses, for example, as a supplemental fuel for power plants.
However, there will be many situations where sewage sludge
and solid waste can be disposed of together with a resultant
conservation of resources.
EFFORTS AND TRENDS
In many cases, the pressures for improving sludge disposal’
practices have not yet crystallized into decisions on alternatives.
However, the pace is quickening. Positive action is underway,
for example, in those cities that utilize ocean disposal. Those
coastal communities that have been under pressure to modify
the practice of disposing of sludge to the oceans by ocean dis-
posal or by barge have pursued one or all of the following op-
tions: demonstrated that the benefits of sludge disposal to the
ocean (low cost, addition of nutrients) outweigh possible risks;
modified the composition of sludge to meet concentration limita-
tions; and searched for alternative sludge disposal options. De-
spite clamor from various cities, federal and state regulatory
agencies appear to be holding fast to their conclusion that for
sludge with composition outside of the limits suggested risk
outweighs benefit and sludge should be kept out of the ocean.
There have been no reported successes in treating sludge so that
it meets standards. Source control to prevent undesired sub-
stances from entering the sewers and ending up in the sludge
has been suggested, but indications2 are that this method will
not be successful. Most of the cities have settled down to making
sincere efforts to examine alternatives. Major evaluations have
been made for Boston, New York, and Philadelphia. The Los
Angeles-Orange County area and the San Francisco Bay area
have studies underway. The Los Angeles-Orange County study is
especially ambitious and includes large-scale pilot plant evalua-
tions of alternatives.
The potential for environmental hazard from inadequate prac-
tice of incineration of sludge has been addressed by the U.S. En-
vironmental Protection Agency (EPA). Based on an EPA Task
Force study 8 and subsequent action by EPA ’s Office of Air Pro-
grams, standards have been set limiting the particulate loading
from sludge incinerators’ and the quantity of mercury emissions. 5
New construction must meet these standards. Ultimately, the
Office of Air Programs is expected to set air standards for con-
centration of hazardous metals in air. This will impact the con-
centrations of these metals allowed in the stack gases from incin-
erators. These standards will probably not be set in the near
14
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future. When they are, it is likely that requirements can be met
by existing gas cleaning technology.
EPA’s Office of Solid Waste Management Programs has had for
some years an aggressive program for upgrading procedures used
in landfills. They recommend using sanitary landfill and pre-
scribe desirable practices’. They currently have underway a con-
tract study to compare the composition and quantity of leachate
from landfills where sludge was codisposed with solid waste with
leachate from landfills where solid waste alone was disposed.
The EPA has attempted to stimulate and encourage interest in
conserving what is good in sludge by applying it to the land. In
recent years, concern has arisen about use of sludges on agricul-
tural land. Some crops do not have an effective barrier to prevent
uptake of certain metals, and too high a concentration of copper,
zinc, or manganese can stunt crop growth. Indications are that
under practical growing conditions, 7 much higher loadings of
sludge than predicted can be tolerated before crop yields are af-
fected. Nevertheless, current EPA research efforts are emphasizing
practical demonstrations and procedures for using sludge to re-
claim land and grow nonfood-chain crops; whereas, for agricul-
tural land used to grow food crops, research efforts are being con-
centrated on developing an understanding of factors influencing
metal uptake by crops.
Conservation of fuel in incineration is not only a sensible course
from a long-range point of view but is becoming a practical neces-
sity in many areas as natural gas supplies are being limited and
costs of oil are skyrocketing. Several municipalities plan to in-
corporate coal or solid waste with their sludge to raise the heat-
ing value to the autothermic point. 8 Consulting engineers are now
finding that when disposal is to be incineration, pressure filters are
more cost-effective than vacuum filters because they produce a
cake dry enough for autothermal combustion.
PROMISING NEW DEVELOPMENTS
The U. S. Department of Agriculture’s Agricultural Research
Service (ARS) has managed to adapt old technology to sludge
disposal. Composting of solid waste is well known but has been
relatively unsuccessful In the United States. Quantities of solid
Waste generated in a given area and converted to compost have
been too great and have “flooded” the market for compost i i i the
area. Quality of the compost has not been high because of con-
tamination with inerts and plastic. ASS has produced a compost
from woodchips and sludge’ that has a highly acceptable appear-
ance, has some fertilizer value, and, because per capita sludge pro-
duction is less than one-tenth of per capita production of orgAnic
Eolid wastes, is unlikely to saturate the local market for compost.
The most reàent compost process developed by ABS’° is being dem-
15
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onstrated by EPA and Maryland Environmental Services on raw
sludge from the Washington, D.C., Blue Plains plant.
Pyrolysis processes are a new development that may see use for
sludge disposal. These processes have been developed for solid
waste disposal and offer the possibility of producing high grade
fuel. Because volume of gases generated per kilogram of waste
processed is much less than that for incineration, gas cleaning costs
are much reduced. It is possible to include sludge cake in the pyrol-
ysis step. EPA-sponsored studies by the 15. S. Bureau of Mines 1 ’
have shown that much the same product distribution is obtained
for dried sludge as for solid waste at the same processing condi-
tions. The EPA is supporting tests of Union Carbide’s “Purox”
pyrolysis system in which solid waste and sludge will be pyrolyzed
together.
THE FUTURE
It is anticipated that sludge disposal in the 1980’s will be much
different from disposal in the 1960’s. Ocean disposal will be essen-
tially eliminated or else sludge will be reprocessed to meet con-
centration limitations for potentially hazardous substances. Con-
version processes, wherein sludge is converted to an innocuous
form, will be practiced, but instead of incineration alone, coincin-
eration and copyrolysis with solid waste will be practiced. There
will be an increased use of sludge on land, particularly by larger
cities instead of just by small communities as is practiced today.
Landfills will be used less, since nearby sites are continuing to be
filled and standards, such as maximum water content of sludge,
will become stricter.
It is hoped that incentives for good practice will be developed.
Because the sludge being discharged does not have to meet a qual-
ity standard, there is little incentive to do the disposal job well.
There is always an incentive to do the job cheaply, but without the
need to keep product quality high, the net result can be an inade-
quate disposal operation. Efforts to develop standards for sludge
disposal should clearly be made.
Incentives should also be developed to encourage adoption of
methods that conserve resources. Consider a community that eval-
uates use of its sludge to renovate surface-mined land 60 mi
(100 km) away and finds that it is more expensive than destroying
the sludge by incineration. The community has no incentive out-
side of sheer altruism to adopt the course of conservation. This
deficiency should be considered by policymakers and lawmakers
for correction.
LITERATURE CITED
1. Federal Register, 38, No. 198, Part II, 28610-28621 (Oct. 15, 1973) see
particularly 28618-28621.
16
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2. Klein, L. A., Lang, M., Nash, N., and Klrschner, S. L., “Sources of Metals
in New York City Wastewater,” presented before N. Y. Water Poll. Contr.
Assn. Jan. 21, 1974 (later published in J.W.P.C.F.).
3. U.s. EPA, “Sewage Sludge Incineration,” EPA No. R2-72-040, W 72
12631, Washington, D. C. (Aug. 1972).
4. Federal Register, 38, No. 111, Part II, 15406-15415 (June 11, 1973), see
particularly 15411-15415.
5. Federal Register, 39, No. 208, 38064-38073 (Oct. 25, 1974).
6. Federal Register, 38, No. 81, Part II, “Proposed Guidelines for Thermal
Processing and Land Disposal of Solid Wastes.”
7. Hinesly, T. D., “Agricultural Benefits and Environmental Changes Re-
sulting from Use of Digested Sludge on Field Crops,” EPA Report, NTIS
No. PB236 402 (1974).
8. Municipalities of Minneapolis-St. Paul, and Cleveland are examples.
9. Epstein, E., and Wilison, G. B., “Composting Sewage Sludge,” pp 123-128
in “Municipal Sludge Management” (Proc. Nat. Conf. Mimic. Sludge
Management, June 11-13, 1974, Pittsburgh), pub. Information Transfer
Washington, D.C. 1974.
10. Epstein, E., and Willson, G. B., “Composting Raw Sludge,” pp 245-248,
in “Municipal Sludge Management and Disposal 1975” (Proc. 1975 Nat.
Conf. on Munic. Sludge Management and Disposal, Aug. 18-20, 1975, An-
aheim), pub. Information Transfer, Rockville, Md. (1975).
11. Olexsey, Robert, “Pyrolysis of Sewage Sludge,” pp 139-145 (Thid.).
17
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COMPOSTING OF SEWAGE SLUDGE
AND SOLID WASTES MATTER
Józef Cebula
ABSTRACT
The studies on joint composting of sludges and wastes were
carried out in connection with the needs of the combined treat-
ment plant in Gluszyca, which serves to protect the Upper Bystr-
zyca River from pollution. The river catchment area contains a
water supply reservoir and, in addition, is of high touristic and rec-
reational value. For these reasons the region is particularly pro-
tected. 8 The sludge from the treatment plant consists of a mixture
of industrial and technological sludges. Fifty percent of the sewage
comes from textile and tannery industry white the remaining is of
communal origin. The sludge contains low concentrations of or-
ganic matter and other components essential from the point of
view of biological processes and fertilizing properties (CHN and
NPKC a).
The effect of textile and chemical sludges became apparent dur-
ing the course of studies concerning the possibility of joint corn-
posting. The amount of wastes collected in the catchment area was
measured directly. Classification analysis of wastes was made, their
physicochemical composition was determined, and fractions suit-
able for composting were selected.
On a dry-weight basis, the concentration of individual compo-
nents of the wastes, particularly of the organic matter was: RSO,
14%; carbon, 40%; nitrogen, 0.7%; and phosphorus, 0.3%. The
values for Ca, N, and K were lower than those found in wastes
from large cities.
Plastic baskets with perforated walls were used in the composting
experiments, and several series, with increasing percentage of sew-
age sludges from 0 to 10%, were run. Before composting, the
sludge had a greasy consistency, was difficult to dewater, and
emitted a putrid odor. In comparison, the sludge compost had the
structure, appearance, and odor of fertile soil. The compost was
not stieky and was easy to apply on the soil. The compost was
found to stimulate plant growth, as measured by the increase 0
fresh and dry weight and the length of leaves. After analyzing the
18
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results, a 6% to 8 % sludge content and 10 t/ha dose were selected
as optimum. The presence of the following trace elements in corn-
posts and their effects on the growth and composition of test plants
were also investigated: arsenic (As), chromium (Cr), tin (Sn), zinc
(Zn), cadmium (Cd), cobalt (Co), manganese (Mn), copper (Cu),
nickel (Ni), lead (Pb), mercury (Hg), selenium (Sc), silver (Ag),
and vanadium ( If). Mathematical statistics were used to deter-
mine the distribution of trace element occurrences in the compost
and to determine the reliability of the results obtained. Compre-
hensive presentation of trace element distribution for individual
samples and a comparison of such diagrams allowed the conclu-
sion to be drawn that there is some regularity of trace element
occurrence designated as “trace element occurrence periodicity.”
The variability of occurrence periodicity resulting from the
Varying charge of trace elements can be treated as a technological
parameter, which is useful in the determination of sludge suita-
bility for agricultural disposal. This parameter is useful also to
determine the potential toxicity of soil under consideration.
The studies demonstrated that it is technologically feasible to
dispose of industrial sewage and that industrial corn posts are suit-
able for agricultural utilization. It was also recognized that the
presence of trace elements in sludges or composts should be used
as a principal criterion of the suitability of these materials in
agricultural utilization.
INTRODUCT ION
Except for occasional cases of industrial waste waters, sewage
poses no technical or technological problems. On the other hand,
sewage sludges and solid wastes are becoming more and more
dangerous as sources of environmental contamination, and only a
few rational solutions of sludge and waste management practices
are known to eliminate these sources of contalninationjs. 2 s This
is particularly true for sludges of industrial origin because
their increasing amounts make the disposal problem increasingly
dimcult. For the most part they contain a significant load of toxic
chemicals, which are potentially dangerous for the environment.
For this reason the possibilities of sludge disposal on cultivated
land become limited. These chemicals also include trace elements
(heavy metals), which have not been extensively analyzed so far
from the point of view of their environmental effects.
In most cases such sludges are disposed of on dumping sites with-
out being dewatered or are stored in lagoons or on waste lands
where they accumulate and seriously contaminate soil, ground and
surface waters, and air.
Solid Wastes are similarly managed by being dumped in various
uncontrolled Sites, and the use of Sanitary landfills is encountered
19
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only sporadically. 25.27 In specially protected areas* the elimination
of these contamination sources becomes a necessity. It is thus nec-
essary to abandon the traditional methods and to apply newer but,
unfortunately, more expensive methods of treating and disposing
of sludges and wastes.
It has been found that under some conditions it is possible and
advantageous to treat sludges by composting them with solid
wastes. ‘° This procedure produces a much better humus fertili-
zer than the composting of solid wastes alone, and total costs are
lower. Joint cornposting is also advantageous from the hygienic
point of view, because this process totally destroys pathogenic bac-
teria and weed seeds present in sewage sludge.
So far the practice of joint composting has been based mainly
on combining household solid wastes with typical communal
sludges. 1.11.4.5 It has been found, however, that it is possible also
to compost solid wastes with sludges of industrial origin iS. 19.22
and obtain an “industrial compost” as the final product. Successful
final disposal of such compost has become possible by methods de-
veloped in the course of studies carried out especially for this pur-
pose. These methods include the utilization of compost to reculti-
vate parks and sport areas, stabilize slopes, waste heaps, high road
and railroad embankments, and recultivate dumping sites. Under
some conditions it is possible also to use such composts to reculti-
vate forests. 19.20
Such joint treatment provides some technological advantages
and makes possible also a complex solution of sludge and waste
management.
A selection and determination of technical and technological
conditions of correct solutions depend not only upon the character
and composition of both components but also on other factors.
These include the kind and character of the protected area, degree
of environmental contamination, population density, climate, and
technical advancement of the country under consideration.
The Upper Bystrzyca River catchment area was selected for
study because it contains the municipal water reservoir Lubachow,
which has a high recreational value and is, therefore, especially
protected. The protection includes properly managing the sludge
and wastes discharged from the combined chemical and biological
treatment plant “Bystrzyca.” Fifty percent of the sewage is derived
from textile and tannery industries and the remaining 50 ‘7c is of
municipal origin.
The excess of industrial and chemical sludges renders biological
treatment (methane fermentation or oxygen stabilization) impos-
sible. The sludges are thickened and dewatered mechanically on
The specially protected regions include the catchment areas of natural
and artificial water reservoirs, water intake areas of large cities, regions of
recreational value, and national parks.
20
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vacuum filters. Studies concerned with their final disposal and
utilization are the subject of this paper.
Taking advantage of local terrain features and considering en-
vironmental demands, it was decided to treat the sludge and solid
wastes by joint composting, followed by agricultural utilization,
Figure 1 shows the kind and extent of the experimental studies
performed. The studies were divided into Eix research topics:
—the treatment and preparation of sewage sludges for final
disposal;
—the characteristics of household wastes accumulated in the
catchment area;
—the joint composting of wastes with sludge;
—vegetation studies;
—the role and effects on soils and plants of trace elements
(heavy metals) present in composts; and
—the practical aspects of sludge compost utilization (one
small-scale experiment with positive result).
RESULTS AND DISCUSSION
Sewage sludge treatment and preparation for composting
After being thickened and dewatered on vacuum filters, the
sludges were fully analyzed as to their composition, including their
nutrient components. The values for the main components, which
characterize the physico-chemical composition, differ from those
typical of communal sludges. They contain less organic matter and
fewer components essential from the point of view of fertilizing
and biological properties (C,H,N,P,K,Ca); see Figure 2. The pH is
neutral in spite of the high alkalinity of tannery sludge (pH 12).
Characteristics of househo ld solid wastes collected
The interest in this contamination source resulted from the con-
ceived idea of its common treatment with sludges. The studies
included:
—direct determination of the amount of collected waste,
mainly because of the volume mixing coefficient;
—classifying analysis of wastes and determination of physico-
chemical composition;
—selection of waste fractions for composting; and
-determination of waste particle size.
As a result of these studies, it was established that the coarse
and medium fractions can be used in composting. These fractions
amount to about 61 % of waste weight and contain the majority
of organic matter suitable for composting. The composition of
wastes differed from the values quoted in the literature. The con-
centrations of individual components were lower but typical of
21
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Domestic soil wastes
Sewage sludge from treatment pla i ]
determination of solid wastes amount
sampling of solid wastes
classifying analysis of and determination of
selection of waste fractions for composting
determination of waste particle size
study on composting process
and compost analysis
vegetation studios
vegetation studies in Field scale
mixture: textile sludge — 6%
tannery sludge — 3%
municipal sludge — 39%
chemical sludge — Al 7 (SO4 h,-52%
pH
C, H. N
nutrient components. Ca. P. K.
trace elements. As. Cr. Zn, Sn.
Cd. Co. Mn. Cu. Ni. Pb. Hg. Ag. V. Se
analysis of
sludge mixture
temperature measurement
P50 (biodegradable organic matter)
P 150 (nonbiodegradable organic mntter
mineral components. Ca. P. N
trace elements. as in sludge analysis
determination of green and dry mass of plants
determination of trace elements concentration in plants
Fertilization test of grassland with sludge compost
b3
b ’ S
joint compesting with different
contents of sewage sludge
percent =2. 4. 6. 8. 70
Figuue 1. Kind and extent of experimental studiet
-------
I I1F 1 1
1 1 I
10
S
a
4
2
20
110
‘1.2
nit:ogmt —
dcy mat*sf
2 5 O 16 20 30 40 65 60 70
FIgure 2. Contamlnatlofl indices of sewage sludges.
20 55 00
a
a!
0 .B
a!
0.1
65 0%
TABLE 1. PHYSICO-CHEMICAL CHARACTERISTICS OF
CRUDE COMPOST
No.
Characteristic lYnlts
Sludge content as dry weight
percent of compost
.
0
2
4 8
8
10
1
OrganIc matter % s.m.
44.2
51.5
52.3 44.7
39.4
40.7
2
Biodegradable
organic matter % s.m.
13.6
14.3
13.7 18.6
18.6
19.8
3
Nonbiodegradable
organic matter % sm.
30.6
37.2
38.6 26.1
20.8
20.9
4
Total nitrogen % s.m.
0.86
0.63
1.00 0.95
0.93
0.93
5
Total phosphorus % s.m.
0.26
0.26
0.30 0.23
0.31
0.32
6
Total carbon % s,m.
43.0
41.0
40.0 38.5
38.8
—
7
C/N ratIo
65.2
65.1
40.0 40.5
41.7
—
8
pH
8.7
9.0
8.8 8.4
8.5
8.5
9
Moisture % s.m.
50.0
50.0
50.0 50.0
50.0
50.0
10
Calcium mgfg
21.3
14.9
16.3 26.0
21.0
—
11
Sodium mg/g
ö.71
0.35
0.60 1.8
1.20
—
12
Potassium mg/g
3.48
1.95
3.00 3.0
3.92
—
s.m. means % dry weight. —
wastes from small communities in Poland. The biodegradable or-
game matter (RSO) content was 14%; carbon, 40 %; nitrogen,
0.7 %; and phosphorus, 0.3 %. The values of Ca, Na, and K were
lower (Table 1). The per head index of waste accumulation in
small eommuniti s was determined to vary from 0.25 to 0.40 m 8 /yr.
Attempts at joint composting of sludges and wastes
Previous attempts at joint treatment were based mainly on corn-
odium
—
I
I
sohds
-— —--—- 1 rTT T 1 : :
23
-------
bining household solid wastes with typically communal sludges.
In previous and present studies, it was demonstrated, however,
that it is possible also to compost sludges of industrial origin with
solid wastes. In this case, the sludges are not fully neutralized
biologically. The process has been termed “biological masking” of
industrial sludges with solid waste compost. flowever, such a pro-
cedure yields a harmless product, satisfying from the hygienic and
aestetic point of view in comparison with crude sludge or wastes.
The composting experiments were carried out using plastic
baskets with perforated walls to ensure good aeration of the ma-
terial being composted. Several experimental series were per-
formed in which the content of the sludge varied from 0% to 10%.
The volume coefficient of sludge and waste mixing will be within
these limits in technical scale process. The results of test experi-
ments demonstrated that the composting of sludges from the “By-
strzyca” treatment plant is technologically and technically feasible.
Before being composted, the sludges were greasy, were difficult
to dewater, and had a strongly putrid odor. On the other hand, the
sludge compost had the structure, appearance, and smell of fertile
soil. It was not sticky and was easy to apply on fields (Table 2).
Pilot vegeta t ion studies
The purpose of these studies was to establish if sludge composts
had any negative effects on the growth and behavior of plants.
In these studies, the pot tests, adapted to the conditions and pur-
pose of experiments, were used. The growth and development of
test plants were observed under constant environmental condi-
tions, i.e. at constant temperature, moisture, and illumination. After
21 days, the increase of fresh and dry weight, leaf elongation, and
the number of germinating seeds were measured. These indices
were measured at different compost doses.
The sludge compost had a stimulating effect on the increase of
the measured parameters, but it was also essential to determine
the effect of varying the percent content of sludge in compost (Fig-
ure 3). At 2% to 6%, crop yields were higher than those obtained
when sludge alone or with compost made of wastes only were
used. At a 10 % sludge content, the crop yield dropped even below
the level of the control experiment.
After the results were analyzed, an optimum. percent content of
sludges within 6 % to 8 % and a dose of 10 t/ba were selected. It
is assumed that the doses could be higher for grasses because
cereal plants are more sensitive to the effects of inhibitory factors.
Negative aspects of agricultural utilization of composts
In addition to the biogenic compounds assimilated by plants,
sewage sludges contain chemical substances which may have an
adverse effect on plant growth after repeate4, prolo iged applica-
tion on soils.tS 12.21 Research studies carried out so far were con-
24
-------
TABLE 2. PHYSICO-CHEMICAL CHARACTERISTIC OF COMPOST AFTER COMPOSTING.
No. Characteristic — Sludge conte
0 2
nt as per cent
of compost dry weight
4
6
10
1 Organic matter % sm. ’ 40.0 46.2 46.3 44.0 38.5 37.7
2 Biodegradable
organic matter % sin. 10.0 9.6 13.4 15.0 15.1 16.0
3 Non-biodegradable
organic matter % s.m. 30.0 36.6 32.9 29.0 23.4 21.7
4 Total nitrogen % sin. 0.76 0.63 0.65 0.93 0.88 0.85
5 Total phosphorus % s.m. 0.27 0.24 0.27 0.30 0.33 0.35
6 Total carbon % s.m. 41.2 37.4 40.6 39.4 38.3
7 C/N ratio 54.2 59.4 62.5 42.3 43.5 —
8 pH 8.7 8.8 8.8 8.6 8.7 8.4
S Moisture % s.m. 50.0 50.0 50.0 50.0 50.0 50.0
10 Calcium mg/g 22.7 25.5 29.0 27.1 — —
U Sodium mg/g 1.20 2.2 1.9 1.21
12 Potassium rng/g 2.90 2.7 2.0 4.60
* % tin, means % dry weight.
-------
C
S
: 2
C
S
2
a
t
I
a
10.000
COMPOST DOSES kg/ha
Figure 3. increase of fresh (top) and dry (bottom) weight of oats grown on soil
fertilized with compost from the Bystrzyca River basin.
cerned mainly with the fertilizing value of substances present in
sludges and with their effects on crop yields. Only a few studies of
the effects of prolonged agricultural sludge utilization have been
reported. 9.18 One of the problems resulting from the long-term
application of such method of sludge disposal is the accumulation
of trace elements up to the toxic levels. “ “
In discussions concerning environmental quality the term “trace
element” is used for substances ‘which, if present In excessive
amounts, are toxic for plants, animals, and humans. Under unfavor-
able environmental conditions and in the case of non-controlled
sludge managethent, the trace elements can lower crop yields or
even destroy plants. Trace elements can cause diseases in animals
and humans or even death. Such cases are reported in the Japanese
tu
5
-J
COMPOST DOSE, kg/ha
26
-------
and Swedish literature. Lasting destrution of environment can
also be due to trace elements. It is clear that this problem should
be taken into account when agricultural sludge utilization is
planned. 24
Analyzing only the most important fertilizing substances in the
examined composts and observing growth indices are not sufficient
to obtain a full evaluation of the usefulness of these substances in
agriculture. The experiments performed in numerous research
studies indicate that the observed positive effects can be apparent
only. The evaluation criteria should be implemented by deter-
mination of trace elements concentration in plants.
From the available domestic and world literature, the following
trace elements present in higher concentrations in sludges and
waste were selected: arsenic, chromium, tin, zinc, cadmium, co-
balt, manganese, copper, nickel, lead, mercury, selenium, silver,
and vanadium. 2’ 4.10. 111.2$. 21’ Their sources of origin were determined
in detail and their negative environmental effects were pointed
out.
In the course of our studies, an attempt was made to analyze the
levels of these elements in sludge composts, and over 200 samples
of sludge, wastes, and composts were analyzed. Mathematical
statistics was applied to analyze and interpret the results with the
main purpose of determining the occurrence distribution of trace
elements and to verify the reliability of the results. The results are
presented in the probability and log-normal distribution system.
The almost linear shape confirms the correctness of distribution
and the reliability of results.
Comprehensive presentation of trace element distribution for’
individual experiments and then a comparison of these diagrams
indicate that there is some regularity of trace element occurrence.
This regularity was called the periodicity of trace. element occur-
rence (Figure 4).
‘4
U
Figure 4. Trace element concentration in sludge coniposts
27
-------
I
N
Assuming that in soils which were not fertilized with sludges
(Figure 5) the occurrence periodicity is natural, the conclusion
can be drawn that it may be changed upon application of composts
containing a load of trace elements. There will be a moment when
the trace element concentration in the soil attains the critical
value, and plants begin to assimilate individual elements in larger
amounts than required for their growth and development. At this
moment (or state) there is a particular periodicity of trace ele-
ment occurrence. Consecutive shifts in the scale of the diagram,
resulting from the impact of the, trace elements, can be considered
to represent the technological parameter. This parameter deter-
mines the usefulness of sludges in agricultural utilization as well
as their potential toxicity to an individual soil. This parameter
would be, for example, similar to the zinc equivalent.
Our own analytical results are compared with literature data in
Table 3. The concentrations of trace elements in the examined
sludges and wastes do not differ from values found in sewage
sludges from European and American treatment plants. In these
countries such levels of trace elements were considered to be
alarming and to require action to protect the environment. The
character of the Bystrzyca river catchment area has not suggested
that such concentrations of trace elements are present in sludges.
The increased levels in compost are due, therefore, mainly to the
sludges from• tannery and textile industry.
Studies of sludge compost effects on plants included the deter-
mination of concentration changes of some elements in oats, which
were fertilized with various doses of compost having a varying
sludge content. However, no essential effect could be observed at
the doses applied. This may indicate that the trace element con-
centrations in sludge compost are still “normal” or that the plant
Figure 5. Trace element concentrations in test soil.
28
-------
TABLE 3. A COMPARISON OF AVERAGE TRACE ELEMENT CONCENTRATIONS IN SLUDGE AND
SLUDGE COMPOST, ug/g
p4
t o
Sewage sludges
Solid
wastes
from
Bystrzyca
Treatment
Sludge
compost
from
Bystrzyca
Treatment
Test
Poland
Lower
Bystrzyca
Treatment
Element
Arsenic
.
USA
7.5
England
—
Sweden
—
Silesia
21
Plant
30
Plant
19
Plant
14.7
— soil
9.8
Barium
—
1500
—
—
—
—
—
—
Boron
—
50
—
—
—
—
—
—
Chromium
380
260
86
116
140
103.5
92.1
94.1
Tin
—
120
—
—
—
6.4
7.5
7.9
Zinc
Cadmium
2200
12
3000
—
1567
6.7
3305
—
1317
—
664
4.6
579.6
17.3
194
—
Cobalt
Manganese
Copper
Molybdenum
Nickel
—
—
700
—
52
12
400
800
5
80
10.8
386
560
—
5 1
27
416
163
—
52
17
—
194
—
62
30.8
743.5
141.2
—
83.7
45.8
771.6
191.8
.—
71.6
20.4
1017.3
55.5
—
23.2
Lead
480
700
180
353
337
163.4
141.7
143
Mercury
Selenium
3.0
—
20
—
5.0
—
—
24
—
97
0.4
13.5
0.6
27.3
—
16.2
Silver
—
—
—
—
1.9
4.5
1.5
U
Vanadium
—
60
—
54
—
118.3
102.5
73.4
-------
TABLE 4. CONCENTRATIONS OF TRACE ELEMENTS IN
TEST PLANTS
Compost
Sample k a
Trace
eleme
nt, g/g Type of
Mn Fb experiment
Cu Ni
Zn
1
30 52
75
7526
2
50 34
56
43 21 Control test,
3
85 42
39
212 17 only test soil
4
70 61
70
20 60
5
11 96
11
11 11
6
25 85
25
40 75 Experiment
7 5,000
28 100
180
130 174 with compost
8
24 66
19
38 12
9
27 17
175
— —No sludge,
10 10,000
14 14
21
11 87 experiment with
11
17 33
17
25 49 compost
— 12
18 12
90
23 85
13
13 11
26
6545
14 20,000
51 30
47
13 40
15
2855
10
54 54
16
21 17
125
— —
— — 2% sludge,
32 52 experiment with
17 5,000
18
21 17
54 84
—
135
19 10,000
21 17
—
— — compost
20
22 24
20
13 41
21 5,000
30 63
12
40 10 4% sludge,
55 45 experiment with
22
50 88
30
23 10,000
17 15
50
35 12 compost
12 8
24 20,000
9 25
25
25
73 203
20
10 18 6% sludge,
26 5,000
20 43
26
20 11 experiment with
27
70 20
73
11 27 compost
28
5537
160
92 32
29 10,000
76 40
34
13 40
30
82 52
1i
27 1i_
31
46
50
11 29
32 20,000
70 22
49
65 23
2366
23
11 57
30
-------
selected for studies (oats) does not assimilate these elements dur-
ing its vegetative period (Table 4).
CONCLUSIONS
1. Final disposal of sewage sludges of industrial origin is techno-
logically and technically possible by joint composting with solid
wastes. The feasibility of agricultural utilization was demonstrated
by the vegetative tests.
2. The uncontrolled disposal of sludges and wastes creates a ser-
ious danger for the environment quality, particularly in protected
areas.
3. In addition to the main fertilizing components, sludges also
contain trace elements which can inhibit plant growth or can be
toxic, depending on the kind and concentration of individual
elements.
4. The presence of trace elements in sludges and composts should
be considered to represent the fundamental criterion of the use-
fulness of these materials in agricultural final disposal.
ACKNOWLEDGEMENT
This paper is one of the parts of project PR-5-532-8 (PL-480),
undertaken in cooperation with the United States Environmental
Protection Agency.
REFERENCES
1 , Agricultural use of sewage sludge. Notes on Water Pollution, 1972.
2. Andersson A., and Nilsson K. 0. Enrichment of trace elements from sew-
age sludge fertilizer in soils and plants. Amblo 1, 176-199, 1972.
3. ApplIcation of digested sewage sludge on agricultural land. Department
of Agronomy, University of Maryland, 1914.
4. Berrow M. L., and Webber, J. Trace elements In sewage sludges. J. Sc!.
Pd. Agr.tc. 23, 93-100, 1972.
5. Braun, R. Die wesenthliclten Probleme der gemeinsamen kompostierung
von K.larschlaznin und Mull. Kontunalwirtschaft, No. 9, 339-846, 1965.
6. Braun B. Problem usuwania nleorganicznych osadow przemyslowych.
EAWAG Zurych-Dubendort. (Thnnaczenie) Dechentarnonographien,
band. 64, 1970.
7. Cebula, J. The utilization and disposal of sludge from combined treat-
ment plant (sewage and waters from cotton, linen and! tannery industries)
together with municipal solid wastes. Maszynopis Bibi. IMGW, 1973.
8. Cebula, 3. Wspolne unleszkodliwianie osadow sciekowych I odpadkow
Jako racjonalana metoda calkowitego unleszkodllwianla osadow. 1GW.
Zaklad Ochrony Wod. Maszynopis / nie publikowane/. Wroclaw, 1970.
9. Cebula J. Report on study tour to Austria, Switzerland, Federal Republic
of Germany, and United Kingdom under a Fellowship. Programme of
the World Health Organization. Maszynopls. BIbI. IMGW, 1972.
20. Channey, It. Crop and food chain effects of toxic elements in sludges
and effluents. Proc. Con!. July 9, 13, 1973. Nat. Assoc. Univ. and Land-
Grant Coil. Washington, D.C. 129-141, 1973.
31
-------
11. Chumbley, C. G. Permissible levels of toxic metals in sewage used on
agricultural land. Ministry of Agriculture, Fisheries and Food, 10, 1—12,
1971.
12. Coker, E. G. Utilisation of sludge in agriculture. 4th Public Health Engi-
neering Conference, London, 87-104, January, 1971.
13. Coker, E. c i The value of liquid digested sewage sludge. J. Agric. Sci.
Camb. 67, 91-97, 1966.
14. Dean, R. B. Ultimate disposal of waste water, a philosophical view.
Chemical Engineering Progress Symposium 65, 97, 1969.
15. Dean, R. B. Ultimate disposal of advanced waste treatment residues.
TAPPI J. of the Tech. Kss. of the Pulp & Paper Industry. Vol. 52, No. 3,
457-460, 1969.
16. Dean, R. B., and Smith, 3. E., Jr. The properties of sludges. U.S. En-.
vironmentaj Protection Agency/U.S. Dept. of Agriculture, Universities
Workshop, Univ. of Illinois, Urbana, Illinois, July 9-13, 1913.
17. Duggan, J. C. Utilization of municipal refuse compost. 1.-Field-scale
compost demonstrations. Compost Science, 2, 1973.
18. Hirschheydt, A. Mineral industrial sludges and composting. ISWA, In-
formation Bulletin 1, 29-30, 1969.
19. Hirschheydt, A. Industrieschlamme in der Mullkompostierung?
Komunalwirtschaft 1, 1-6, 1969.
20. Hirschheydt, A. Verwertung von Komposten, Industrie - und Gewerbe-
abfallen. Symposium: Umwaltprobleme und Landwirtschaft, Bern, 13/14,
235-241, 1971.
21. Hirschheydt, A. Landwirtschaftliche Klarschlamm-Verwertung. EAWAG,
No. 4185, Dubendorf, 1971.
22. Hirschheydt, A. Uber Versuchezur Beseitigung von Abfallolen und
olhaltigen Abfallen mit Hilfe der Kompostierung. Wasser und Boden,
10, 31.6—318, 1972.
23. Kabota-Pendias, A., and Pendias, H. Szkodliwose nadmiernego stezenia
metali ciezkich w srodowisku biologicznym. Zeszyty Problemowc Poste-
pow Nauk Ro lniczych. 145 pp. 1973.
24. N lshima, T., et al. Mercury, lead, and cadmium contents in hair of resi-
dents in Tokyo metropolitan area. Annual Rep. Tokyo Metropol. Ret.
Lab. Public Health, 23, 277-282, 1971.
25. Page, A. L. Fate and effects of trace elements in sewage sludge when
applied to agricultural lands. EPA Report 670/2-74-005, 1974.
26. Rudolf Z. I inni. Usuwanie I wykorzystanie odpadkow miejsklch. Arkady
Warszawa, Poland, 1975.
27. Rudolf Z. I inni. Kompostowanie wspolne osadow sciekowych z odpad-
kami miejskimi mb stalowymi. Mat. VU Konferencjl Naukowo-Tech-
nicznej “Postep w dziedzinie oczyszczanla sciekow.” Katowice, Poland,
1964.
28. Zarys rozwoju oczyszcania miast do r. 1985 Minlsterstwo Gospodarki
Komuna lnej. Warszawa, Poland, 1967 (maszynopis powlelony).
32
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EFFECT OF WATER WORK’S SLUDGE
ON WASTEWATER TREATMENT
Janusz Zakrzewski
ABSTRACT
The paper presents results of laboratory research work designed
to evaluate the influence of the post-coagulation sludge obtained
during water treatment and the filter-washing water (1) on the
process and results of municipal sewage treatment and (2) on the
process of municipal sludge disposal. The post-coagulation sludge
samples have been taken from the Pulsator and front swntples of
the filter-washing water from rapid filters—all at the Central
Warsaw Water Works. Municipal sewage samples have been col-
lected at the Zoliborz-District Pumping Plant, Warsaw.
Results of investigations lead to the following conclusions:
1. The influence of post-coagulation sludge on the mechanical
treatment (primary settling) of municipal sewage is limited.
2. The influence of post-coagulation sludge on the biological treat-
ment (activated sludge process) of municipal sewage is limited,
too .
3. No important difference in total effect of ‘m.echanical -biological
treatment of municipal sewage should be expected as the result
of presence of post-coagulation sludge in raw sewage.
4. Although the addition of post-coagulation sludge slightly de-
creases the effect of thickening and digestion of sludge, it does
not influence these processes considerably.
5. Further investigation using large-scale equipment should be
undertaken to verify the results of these small-scale experi-
ments.
Notice: The term “post-coagulation sludge” used in the conclusions
above means a mixture of the sludge from water coagulation pro-
cess and filter-washing water mixed in proportions of 1:8.
INTRODUCT ION
The combined treatment of municipal sewage and post-coagula-
tion sludge may be considered as one of the methods of sludge
neutralization. Polish specialists, as well as specialists of many
other countries, have a concern in this method. However, there
are serious divergences of opinion on the influence of the alumin-
33
-------
ium sludge and filter-washing water on the process of municipal
sewage treatment and sludge utilization. This is why the investiga-
tions in this field have been undertaken in Poland, under the
agreement with the United States Environmental Protection
Agency, within the Project PR-05-532-7 entitled “Neutralization and
Utilization of Post-coagulation Sludge.” This paper presents re-
sults of laboratory research work conducted by Dr. Jadwiga Ber-
nacka.
THE OBJECTIVE AND SCOPE OF THE INVESTIGATIONS
There were two objectives of this research work: 1) evaluation
of the influence of the post-coagulation sludge and filter-washing
water on the process and results of municipal sewage treatment;
2) evaluation of the influence of post-coagulation sludge and filter-
washing water on the process of the municipal sludge disposal.
The term “post-coagulation sludge” in this paper means a mix-
ture of the sludge from the water coagulation process (sludge
obtained in Pulsator) and filter-washing water (mixed in propor-
tion 1:8).
The scope of the work in the first objective included the follow-
ing problems:
—determining the characteristics of the post-coagulation
sludge (the mixture),
—investigating the influence of the post-coagulation sludge
on the sedimentation process of municipal sewage,
—determining the quantitative and qualitative characteristics
of primary sludge obtained as a result of investigations
mentioned above,
—investigating the influence of post-coagulation sludge on the
activated sludge process of biological treatment of munici-
pal sewage, and
—establishing the primary and excess activated sludge bal-
ance.
The scope of the work in the field of the second objective in-
• cluded:
—investigating the ability for gravitational thickening of the
primary sludge and excess activated sludge mixture ob-
tained as a result of investigations mentioned above,
• —investigating methane digestion of primary sludge and ex-
cess activated sludge mixed in the proportion encountered
in conventional wastewater treatment,
—investigating aerobic stabilization of the excess activated
sludge, and
—testing effect of polyelectrolytes on centrifugation of sludge
(effects of shear).
Research Approach
The starting point of the research work was establishing the
34
-------
mixture called here the post-coagulation sludge, e.g. establishing
the voluminal proportion of sludge obtained in Pulsator as a re-
sult of water coagulation process and filter-wash water. These
two ingredients have been mixed in proportion 1:8 (1+7). This
proportion has been assessed on the basis of water and sludge
quantities produced daily at the Central Warsaw Water Works
where samples have been collected.
The water samples were collected each minute of the filter wash-!
ing period (10 ruin) and then mixed. The sludge was collected
directly from the sedimentation cone of the Pulsator.
Municipal sewage samples were collected at the Zoliborz-Dis-
trict Pumping Plant (Warsaw), where domestic and small-indus-
trial-works sewage are received.
The analysis of post-coagulation sludge included the following:
pH value, putrescibility, BOD 5 , COD, total dry solids, mineral and
organic matter, suspended solids (total, mineral, organic), settle-
able suspended solids, and aluminium.
The analysis of sewage before and after treatment included the
following: pH value, putrescibility, BOD 5 , COD, suspended solids
(total, mineral, organic), settleable solids.
The analysis of sludge obtained in the sewage treatment process
included the following: pH value, dry solids (total, mineral, or-
ganic), moisture, CST (capillary suction time). In optimum sam-
ples, the ether extract, total nitrogen, and aluminium have been,
additionally, determined.
Mixtures of municipal sewage and post-coagulation sludge have
been prepared in several voluminal proportions as follows: 100:2;
100:3; 100:5; 100:8. The proportions 100:5 and 100:8 followed the
relationship between the quantity of water produced in the Cen-
tral Warsaw Water Works and the quantity of resulting filter-
wash water and Pulsator sludge. Some investigations have been
performed to evaluate the influence of Pulsator sludge alone (with-
out mixing with filter-wash water) on the sewage treatment proc-
ess, applying proportion 100:5. The results of all of these investi-
gations have been compared with the results of municipal sewage
treatment process without the post-ëoagulation sludge (blank run).
DISCUSSION ON THE INVESTIGATION RESULTS
Post-Coagulation Sludge Characteristics
Eighteen (18) samples of post-coagulation sludge have been
analyzed, and limit values of results are presented in Table 1. The
moisture of sludge was high and significant amounts of mineral
compounds were found. The average moisture was 99.93 % and the
content of mineral matter in dry solids was 73.3 %. The content of
mineral matter in dissolved fraction and in suspended solids was
also high, 69.3% and 75.2%, respectively. The average value of
sludge putrescibility was 0.9 hr, which is evidence of its low sta-
35
-------
TABLE 1. CHARACTERISTICS OF
POST-COAGULATION SLUDGE
Characteristic
Units
Values
M m .
Max.
pH value
pH
6.2
7.6
Putrescibility
hours
0.4
n.p.
BOD ,
ppm
40
120
COD
ppm
68
640
Total dry solids
ppm
358
1,308
organic
%
18.3
34.5
mineral
%
65.5
81.7
Total dissolved matter
ppm
196
696
organic
%
7.6
44.2
mineral
%
49.5
92.4
Total suspended solids
ppm
122
904
organic
%
18.6
50.5
mineral
%
49.5
81.4
Moisture
Aluminium
%
ppm
99.91
20
99.96
112
= not putrescible; did not putrify in the time duration of the test.
bility. The average aluminium content was 54 ppm, which on the
average amounted to 7.7 % of the dry solids. High variations in
BOD , and COD values were observed (3 to 9 times). The average
values of these indicators were BOlD 5 , 80 ppm; and COD, 163 ppm.
Municipal Sewage Characteristics
The results of municipal sewage analyses are presented in Table
2. Composition of municipal sewage samples varied, presumably
because of periodic dumping of industrial waste, which was made
evident by low pH values, even below pH 4.
TABLE 2. CHARACTERISTICS OF MUNICIPAL SEWAGE
.
Characteris
.
tic
.
Units
Val
ues
Average
•
Mm.
Max.
pH value
pH
3.7
7.5
6.1
Putrescibility
hours
6
n.p.
—
BOD ,
ppm
104
353
216
COD
ppm
228
470
329
Total suspended
solids
ppm
87
149
117
organic
ppm
55.9
115
87.6
mineral
ppm
19.5
37.3
29.8
36
-------
The Influence of Post-coagulation Sludge on the Sedimentation
Process of Municipal Sewage
The results of investigations in this field can be summarized as
follows:
—The addition of the post-coagulation sludge to the municipal
sewage slightly increased the effect of mechanical sewage
treatment. When the proportion of post-coagulation sludge
in sewage was 2 U/(, 3 %, or even 5 %, its influence on the
sedimentation process was insignificant. The influence be-
came well marked when the proportion was 8%. Then the
average removal of suspended solids and average reduction
of BOD 5 and COD increased 12.4 %, 19.9 %, and 26.2 %,
respectively, in relation to the removal and reduction of
these indicators in municipal sewage.
—The addition of post-coagulation sludge to municipal sewage
at assumed quantities (2 % to B %) caused a slight decrease
of BOD 1 and COD values and an increase of total suspended
solids in the mixtures, according to the increase of post-
coagulation sludge volume in the mixture. The content of
organic matter in total suspended solids decreased together
with the simultaneous increase of mineral matter.
—When sedimentation time was Increased, the effects of treat-
ment increased significantly (BOD 5 and COD reduction,
suspended solids removal). As a consequence, the influence
of post-coagulation sludge on the mechanical treatment pro-
cess became smaller.
—The mixtures of pest-coagulation sludge and municipal sew-
age in proportions of 5:100 and 8:100 have been selected as
appropriate for the investigations on biological sewage
treatment. As stated above, such proportions aS compatible
with the balance of post-coagulation sludge produced in
water treatment plants in relation to water production.
—The addition of post-coagulation sludge caused only a slight
increase of aluminium in the mixtures after the sedimenta-
tion process.
Primary Sludge Characteristics
During investigation of sedimentation process, sludge obtained
after 1, 1½, and 2 hr sedimentation was analyzed, and the increase
in sludge volume when post-coagulation sludge was included in
the wastewater was observed. This increase was larger as the
amount of post-coagulation sludge in the mixture was increased.
The concentration of organic matter in dry solids of sludge de-
creased as the proportion of post -coagulation in the wastewater
was increased. The sludge from municipal sewage contained large
amounts of grease—on the average 19.4 % dry solids. Concentra-
37
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tion of grease in mixed samples decreased and was on the average
15.9% (sample 5: 100) and 13.4% (sample 8:100). In municipal
sludge, the content of aluminium in dry solids of sludge averaged
0.5% and increased to 1.9% in the mixed sample (8:100). The pres-
ence of aluminium in municipal sludge was presumably caused
by the aluminium contained in the alumino-silicates ordinarily
found in soil. The capillary suction time (CST) of sludge was
small and decreased slightly in mixed samples.
Influence of the Post-coagulation Sludge on Biological Process of
Municipal Sewage Treatment
The parameters of sewage treatment process, using activated
sludge, were: capacity of aeration tanks—9 liters each; the aera-
tion time—S hr; concentration of activated sludge—2,500 to 3,500
ppm; hydraulic loading—4.7 m’/m 4 day; primary sedimentation time
—either 0 or 2 hr; secondary sedimentation time—about 2 hr; con-
centration of dissolved oxygen—about 6 ppm. The results of investi-
gations in this field can be summarized as follows:
—Addition of post-coagulation sludge did not cause any
significant change in the qualitative composition of activated
sludge rnicrofauna. Some quantitative differences have been
observed. It should be stressed that the addition of post-
coagulation sludge limited the development of filamentous
bacteria. The occurrence of ifiamentous bacteria in activated
sludge affected the fioc character of activated sludge. The
reticulate structure of sludge caused by the presence of
filamentous bacteria in the floc, negatively affected the
sedimentation properties of sludge.
—No significant influence of post-coagulation sludge on the
process and effects of biological treatment of municipal sew-
age was observed.
—Activated sludge in tanks supplied with the mixtures of
post-coagulation sludge and municipal sewage is essentially
the same biotic community familiar to the activated sludge
in a tank supplied with municipal sewage only.
—During the whole investigation period, the filaznentous bac-
teria content tended to decrease; this resulted in a decreased
sludge index. As the sludge index became lower, the sludge
sedimentation properties increased.
—Municipal sewage mixed with post-coagulation sludge can
undergo biological treatment without primary sedimenta-
tion. With the same aeration time, the results are similar for
biological treatment of municipal sewage mixed with the 5 %
of post-coagulation sludge with or without the primary
sedimentation.
38
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The Primary and Excess Activated Sludge Balance
The results of investigations are presented in Table 3.
TABLE 3. EFFECT OF POST -COAGULATION SLUDGE ON
TOTAL SLUDGE VOLUME AND MASS
.
Municipal
sewage
Volume ratio of post-
coagulation sludge to
wastewater flow
5:100 8:100
Volume of primary sludge
produced after 2 hr
2.9
4.6 5.9
sedimentation
dm 3 /m 3
dm /m 8 dm 3 /m 8
Relation of volume of primary
sludge to excess activated
sludge
1.3:1
1.6:1 2.2:1
Above, expressed in dry solids
4: 1
3.8: 1 2 : 1 —
Effect of Thickening the Mixture of Primary Sludge and Excess
Activated Sludge
The best gravitational thickening effect was achieved by the
municipal sludge without post -coagulation sludge. Average solids
content of the thickened sludge was 2.66 %. Slightly lower degrees
of thickening have been gained for the mixtures containIng 5%
or 8 % of post-coagulation sludge; solids contents of the thickened
sludge were 2.1 and 1.78, respectively. The lowest degree of thick-
ening (1.35 solids) was for the excess activated sludge containing
5 % of post-coagulation sludge but no sludge from the primary
clarification.
As the volume of post-coagulation sludge in the mixture In-
creased, the optimum thickening time increased slightly. At the
same time, however, the degree of thickening decreased. Capillary
suction time of sludge (CST) after thickening increased In accord
with the increase in volume of the post-coagulation sludge in the
mixture.
Effect of Post-Coagulation Sludge on the Methane Digestion of the
Mixture of Primary Sludge and Excess Activated Sludge
Post-coagulation sludge evidently influences the effectiveness of
the methane digestion process. The presence of post-coagulation
sludge has caused the rate of digestion to decrease. The greater
the quantity of post-coagulation sludge in the mixture, the greater
the influence; this could. be observed by the smaller quantities of
gas (methane) generated. With a mixture of 5% of post-coagula-
tion sludge, the average decrease of production of methane was 8 %
39
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and with 8% post-coagulation sludge, the decrease was 17.5%.
A 21- to 28-day digestion time should be allowed; the effect of a
14-day process might be insufficient. Second stage digestion de-
creased the water content of the mixed sludge, and the longer the
digestion process, the less polluted was the effluent.
Effect of Aerobic Stabilization of the Excess Activated Sludge
The activated sludge (containing post-coagulation sludge) re-
quired 14 days for aerobic stabilization. The aerobic stabilization
process improved the ability of this sludge to thicken.
CONCLUSION
Results of investigations on the influence of aluminium sludge
and filter-wash water on the process of municipal sewage treat-
ment and sludge utilization lead to the following conclusions:
1. The influence of post-coagulation sludge on the process and on
the effect of mechanical treatment of municipal sewage is
limited.
2. The influence of post-coagulation sludge on the process and
effect of biological treatment of municipal sewage is limited,
too.
3. No important difference in total effect of mechanical-biological
treatment of municipal sewage should be expected because of
the presence of post-coagulation sludge in raw sewage.
4. Although adding post-coagulation sludge slightly decreases the
effect of thickening and digestion of sludge, it does not influence
those processes substantially.
5. Further investigation using large-scale equipment should be
undertaken to examine the results of the lab-models work.
40
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PHYSICAL-CHEMICAL TREATMENT
OF COMBINED STEEL MUNICIPAL WASTEWATER
Jan Suschka
ABSTRACT
Combined steel and municipal wastewater can be treated effec-
tively using biological methods. However, the removal rate for
organic substances seems to be lower than that for municipal sew-
age. Using physical-chemical treatment does not have an advantage
especially when high-quality effluent is required. The investiga-
tions carried out indicate that thorough mixing associated with
aeration and sedimentation essentially removes pollutants. Adding
anaerobic digested sludge further improves the treated wastewater
quality. However, more research is needed to evaluate optimal
conditions.
THE SCOPE OF THE RESEARCH
Wastewater originating mostly from steel’ and related industries
is characterized by the presence of metals and other substances
that can have an inhibitory effect on biological treatment. Investi-
gations on the activated sludge process and trickling filters show a
lower kinetic rate of removal of organic substances than that of
municipal wastewaters. Probably the most important reasons are
the inhibitory substances from industry and the shock loads that
can be responsible even for complete destruction of the active
biological fioc.
Another reasonable approach seems to be physical-chemical
treatment, direct or after primary sedimentation. This approach
was reported by many authors to be effective when treating waste-
waters of low organic content. In contrast with the use of classical
coagulants and polyelectrolytes, the possibility of using substitute
substances was examined in the scope of this work.
The combined wastewater originating in part from steel mills
and metal finishing plants contained relatively high iron concen-
tration. The maximum concentration varied in the range of 70 to
80 mg/l. The average concentration was about 25 mg/L Sludge
from primary or secondary settling tanks is characterized by a
concentration of about 200 g Fe/kg of dry matter. It was then sug-
41
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gested that the applicability of sludge derived from different points
of the wastewater treatment process be investigated as an aid or
single coagulant for wastewater purification.
To get the desired information, iaboratory and pilot-scale re-
search was done on the effect of treatment with classical coagu-
lants. Also, research on the activated sludge process, trickling
filters, and aerobic and anaerobic stabilization of sludge was done.
WASTEWATER CHARACTERISTIC
The average flow of wastewaters to be treated is about 1.5 m 3 /sec.
The flow varies during the day from about 1.0 to 1.8m /sec. During
rainy periods, the flow can Increase up to 7 m*/sec. Many 24-hr
samples (hourly composites) of combined wastewater were exam-
ined, as were grab samples. AlSO, before each treatment, the waste-
waters were examined. To understand the magnitude of the param-
eters measured, the average values and the range of pollutant
concentration are given (Table 1). The maximum values given in
Table I do not include the extreme values that can be found only
occasionally.
TABLE 1. CHARACTERISTICS OF THE COMBINED
WASTE WATERS
Parameter Average Minimum
Maximum
pH
7.5
6.9
8.0
Turbidity, mg/l Si 02
500
100
900
COD, unfiltered, mg/l 02
240
120
540
COD, filtered, mg/l 02
150
60
240
BOD 5 , mg/l 02
110
60
145
Suspended solids
Total, mg/l
190
100
350
Volatile, mg/l
120
60
200
Alkalinity Zm*, mval/l
4.2
3.3
6.4
Zp,mval/I
0
0
0
Calcium, mg/l
125
70
170
Magnesium, mg/l
60
35
95
Sulphates, mg/l
445
230
660
Sulphur total, mg/l
130
85
230
Phenols, mg/l
0.09
0.001
0.2
Cyanides, mg/I
3.5
2.2
4.0
Iron, mg/l
25
6
80
Zinc, mg/l
2.0
0.8
3.2
Lead, mg/l
0.12
0.10
0.15
Copper, mg/l
0.18
0.12
0.30
Ammonia nitrogen, mg/l
32
28
45
Nitrate nitrogen, mg/l
0.8
0.3
4.2
* Alkalinity determined by titration with methyl orange Is given as Zm;
when phenolphthalein Is used as an Indicator, Zp is used.
42
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BIOLOGICAL TREATMENT
Activated sludge, which was investigated for detention times of
1.2 and 4 hr, showed the possibility of effectively removing organic
substances. Under optimal conditions, decreasing BOD to about
10 mg/I and filtering COD to 40 mg/i was possible.
Similar results were obtained for the trickling filter treatment.
After secondary clarification, wastewater turbidity was low (in the
range of 30 mg/i) as was the concentration of suspended solids
(in the range of 20 mg/I). The quality of biologically treated
wastewater was high even with a relatively high load of organic
substances (in the range of 0.5 to 1.0 g BOD/g MLVSS per day.
AEROBIC AND ANAEROBIC SLUDGE STABILIZATION
Primary sludge was aerobically stabilized for 10 days. Because
of the biooxidation of a part of the organic substances, the relative
concentration of inorganic substances increased. The concentra-
tion of total iron in relation to dry matter changed slightly during
the process—from 16.7 % to 16.9 % in one run and from 17.6% t O
22.8 % in the second run. The fractions of VSS after aerobic sta-
bilization were 48.6 % and 40.4 %, respectively, i.e., 15 % lower
than at the beginning.
The process of anaerobic stabilization was carried out at a tem-
perature 32°C with detention times of 29 and 36 days. The respective
loads were 0.14 and 0.15 kg dry matter/rn 3 per day. The gas pro-
duction was 1.15 m 3 /m 3 . The iron content in the digested sludge
was relatively low (in the range from 7-12%). The process of iron
solubilization was observed. In the supernatant, the soluble iron
increased from 6 and 12 mg/i to 27 and 46 mg/i, respectively, in
two runs.
The aerobic and anaerobic digested sludge as well as the anaero-
bic supernatant was used to investigate wastewater coagulation.
PHYSICAL-CHEMICAL TREATMENT
The major part of this research was based on jar tests although
several series of continuous laboratory and pilot-scale investiga-
tions were carried out. Before going into the results of the true
coagulation process when ferrous or alum salts or other chemicals
were added, it seems to be Important to mention the effects of
mixing and sedimentation on the wastewater quality.
During the jar-test investigations, it was found that plain 1 ! min
rapid and 20-mm slow mixing followed by a 30-zulu sedimentation
time results in distinctive changes in wastewater quality. Because
of this simple process,! the turbidity decreased on the average, from
500 to 95 mg Sf0, (in the range of 80%) . This was also true of
suspended solids removed; the average suspended solids concen-
tration decreased from 190 to 40 mg/I (about. 80 %). But only a
43
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2 % COD removal was obtained from a filtered sample; that, of
course, could be expected. The observations made are very impor-
tant when discussing the problem of physical-chemical treatment
of wastewater. They show explicitly how important the primary
treatment stage, including mixing, is.
From many experiments it was concluded that primary treat-
ment is best when preaeration process is used. This process, lasting
from 10 to 30 minutes, results in thorough mixing and oxygenation.
Besides improved removal of suspended solids and turbidity, heavy
metals can be removed during the sedimentation process. 1 An
example of the effects of preaeration process for removing sits-
pendéd solids and turbidity is given (Figure 1). It was demon-
strated that preaeration removes more turbidity and suspended
solids than does plain mixing and sedimentation. Adding lime to
raise the pH to 8.5, 9.0, and 9.5 (from 7.4) has little or no advan-
tageous effect (Figure 1).
600
400
500
4- ’.
N
0
U )
a)
E
5
— 200
100
100
50
4. -.
0 )
E
C ’ )
C
9
0
uJ
I
0 1 2 3
SAMPLE NO.
F Igure 1. Effect of preaeration on removal of suspended solids and turbidity.
Sample 0 involved plain mixing and sidimentatlon; Sample 1, 30
minutes of preaeration; Sample 2, 30 mInutes of preaeratlon and pH
raised to 8.5; Sample 3, 30 mInutes of preaeratlon and pH raIsed to 6.0.
44
-------
On the base of many investigations, it was demonstrated that
increasing pH through lime addition cannot be justified as a treat-
ment process. From Figures 2, 3, and 4, where the mean values
as well as the ranges are given, it is obvious that further distinctive
improvements of the wastewater quality can be achieved.
I
I 1i
E s
j I i
v9 .
FIgure 2. Effect of using different chemicals, substances, or process conditions
on turbidity.
Even in the case of suspended solids, an unexpected increase was
observed. The turbidity at pH above 9.0 decreased to 40 mg/I, that
is, to about 60 % of the plain mixing-sedimentation process. Also,
a 20 % removal effect of COD was obtained by pH increase.
The Figures 2, 3, and 4 comprise also the results of investigation
with the use of other classical coagulants. In relation to the scope
of this research, it seems to be important to compare the results
achieved when using incinerated and anaerobic digested sludge in
place of chemicals.
From the results presented in Figure 2, it is evident that the tur-
bidity of wastewaters treated with incinerated sludge is compar-
able with that obtained at pH 9.5 with the addition of copper or
at pH increased to 8.5 and 9.0 with addition of alum.
Similar conclusions can be derived ‘comparing the results of
suspended solids and COD removal.
It has to be stressed that similar results for COD removal (in
the range of 45 % with a remaining value of 60 mg/I) could be
obtained only when alum and alum in addition to fly ash was used.
000
800
700
800
‘a
I
400
200
45
-------
‘ I ,
4’
U,
400 —
300— V
o
0 a
o °‘I S
(a — •5.
2O0- 4, n
H fl I
I I II 8
U ) = II I I 0
100 - __ ‘ 4 ,
0. S
__ II U ’ ._ Z .2’
t. l ‘ nfl °fli er
r 4 LJl
Figure 3. Effect of using different chemicals, substances, or process conditions
on suspended solids. Mean value indicated at
4OO 8
}300- ; 3m
I £ 1 tI
12 1 “ 1 1 3
nfl A I I çj
‘0’ ‘Lr !i eG
tn—UI in
Figure 4. Effect of using different chemicals, substances, or process Conditions
on COO. Mean value Indicated at
Satisfactory coagulation was also obtained when anaerobic digested
sludge was used. In Figure 5 are the results obtained with two
different doses of anaerobic digested sludge.
With an excellent removal value of as low as 22 mg/l, the con-
elusion is that the use of sludge as a coagulant or a coagulant aid
seems to be very promising. However, it is too early to scale up the
results to a full technical scale, for a time limitation allowed only
several runs. Also, the use of incinerated sludge was tested during
a rainy period of the year and wastewaters were relatively “weak”
when compared with the average values.
Treating combined steel/municipal wastewater with physical-
chemical methods has no advantage over biological methods; the
only justification for using physical-chemical methods is the usE of
substitute coagulants.
46
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120
100
: 0 10 20 30
SLUDGE DOSE, rng Fe/liter
Fliure 5. Effect of using anaerobic digested sludge on turbidity and suspended
solids
160
140
47
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COMPARISON OF ALTERNATIVE STRATEGIES FOR
COKE PLANT WASTEWATER DISPOSAL
Robert W. Dunlap and Francis Clay McMichael
ABSTRACT
Fifty years ago the production of coke from byproduct ovens
sur passed the production from beehive ovens. Although oven-coke
production has remained stable, chemical recovery has grown in-
creasingly less advantageous. By 1973, coal chemicals amounted to
only 12% of total product value. Recently, attention has been
focused on another principal difference between byproduct and
beehive coking, namely water pollution as a result of gas treatment
and byproduct recovery.
In 1974, the U.S. Environmental Protection Agency issued efflu-
ent guidelines and standards for iron and steel manufacturing.
Limitations were set for oil and grease, suspended solids, pH, and
sulfides, but the principal attention for the guidelines was for the
control of ammonia, cyanide, and phenols.
This study examined a number of topics related to coke plant
wastewater problems. Answers were sought to these questions:
What are the specific sources of the wastewaters? Can they be
reduced by process changes? How do process changes and waste-
water treatment impact air, land, and energy demands?
Seven different wastewater treatment strategies were evaluated
considering the mass emission inventory and cross-media analysis.
The findings were that wastewater treatment provides environ-
mental improvement for one media, water, but, will lead to the
degradation of other media, dir and land. Energy requirements for
treatment processes create new pollutant residuals, which are
smeared across all media.
For some wastewater treatment practices, the new environmental
improvement due to the practice is negative, i.e., cross-media ef-
fects are so large as to negate the beneficial effects of improving
t1 e water media. The results of this study clearly support the
contention that levels of environmenta.l control must be considered
very carefully if maximum improvement of the environment is
to take place.
48
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TRENDS IN COKE MAKING
Fifty years ago, the production of coke from byproduct ovens
first surpassed the production from beehive ovens. For many of
these same years, the byproduct process was praised for two sig-
nificant advances over beehive coking: first, byproduct processing
introduced significant chemical recovery into coke making and
second, byproduct processing significantly reduced air pollution
problems associated with coking. The last 20 to 25 years, however,
have brought a changed perspective. While oven-coke production
has remained stable at 54 to 64 million metric tons/yr over the last
quarter century, chemical recovery has grown increasingly less
advantageous. In 1950, 22 % of product values from the coke plant
were associated with the value of coal chemicals. 1 By 1973, coal
chemicals represented only 12 % of total product value. At the
same time these changes were taking place, increasing attention
has been focused on the other principal difference between byprod-
uct and beehive coking, namely, the introduction of significant
water pollution problems which are a direct consequence of the
gas processing.
EFFLUENT GUIDELINES
Coke plant effluent limitations have been imposed by the U.S.
Environmental Protection Agency (EPA) 2 It is recognized that coke
plant wastewaters are typically as saline as sea water and contain
a broad range of organics. Limitations are set for oil and grease,
suspended solids, pH, and sulfides, but the principal attention for
the guidelines are for the control of ammonia, cyanide, and phe-
nolics. By 1977, the guidelines call for more than 90 % reduction
of these pollutants from the levels in typical untreated process
waters. Further control by 1983 is expected to reduce discharges
of the three by more than 99% (Table 1).
The intent of this study is to address the coke plant wastewater
problem by examining a number of topics. What are the specific
sources of the• wastewaters? Can they be reduced in quantity
TABLE 1. EFFLUENT LIMITATIONS FOR SELECTED
COKE PLANT POLLUTANTS, kg/mU kg coke
Typical raw
BPCTCA*
BATEAf
Pollutant wastewaters
Ammonia 914
1977
91.2
1983
4.2
Cyanide 120
Phenol 262
21.9
1.5
0.1
0.2
Average percent removal 1O%
— 91.2%
9 ? ?%
* BPCTCA is “best practicable control technology currently available
(other than publicly owned treatment works).”
t BATEA Is “best available treatment technology economically achiev-
able.”
49
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through process changes? How do process objectives and environ-
mental demands like control of air pollution influence waste char..
acteristics? How can we evaluate the environmental impacts to
air, water, and land which result from process effluents or are
associated with the energy demands of process control?
COKE PLANT WASTE WATER SOURCES
Byproduct coke plants vary widely In size, extent and type of
byproduct recovery, and wastewater practices. Wastewaters in
coking originate from three principal sources: coal moisture, water
of decomposition, and process waters added during gas treatment
and byproduct recovery. The process waters are the largest fraction
of the total wastewaters and typically account for 60 % to 85 %
of the total flow, which may range from 500 to 1700 I/metric ton
depending on the level of process water recycle. Typical gas proc-
essing and recovery steps are shown in Figure 1, which indicates
the six categories of wastes normally identified: (1) tar still waste-
water, (2) excess or waste ammonia liquor (WAL) from the pri-
mary cooler, (3) ammonia absorber and crystallizer blowdown,
(4) final cooler wastewater blowdown, (5) light oil (benzol)
plant wastewater, (6) gas desulfurizer and cyanide stripper waste -i
water. Table 2 indicates the level of wastewater flow and mass
emissions of cyanide, ammonia, and phenol for each of the waste-
WATER EVAPORATED WATER
(150 gil/ton)
__ COKE __
OVR4S
COKE COAL
4200 tao/day) (5000 tons/doy)
G M
* m Inn)
3SupmW*t)
Figure 1. SchematIc of coke plant wastes
50
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TABLE 2. CHARACTERISTICS OF COKE PLANT
WASTE WATER STREAMS*
Mass flow —
Wastewater stream Flow Cyanide, Ammonia, Phenol,
gpm 1pm kg/day kg/day kg/day
Flow with loose recycle:
1. Tar still 5 20 2 136 132
2. Waste ammonia liquor 100 380 33 3270 794
3. NH 3 crystallizer 100 380 8 6 2
4. Finalcooler 300 1140 164 65 63
5. Benzol 360 1360 4 6 10
6. Desulfurjzer 40 150 246 0 0
Total 3430 3483 iOOT
Flow with tight recycle:
1. Tar still 5 20 2 136 132
2. Waste ammonia liquor 100 380 33 3270 794
3. NH 3 crystallizer 100 380 8 6 2
4. Final cooler 30 110 82 33 40
5. Benzol 65 250 2 2 3
6. Desulfurizer 40 150 246 0 0
Total 4O 1290 3447 971
*Basij 5443 kkg/day coal charged at [ 0% moisturjj,jth 70% coke yield,
equivalent to 3810 kkg/day coke product.
water streams. Loose or tight recycle is a measure of the flow
reduction achieved through recycle and process modification in
the final cooler and the benzol plant. Mass emissions are essentially
the seine for both configurations with the exception of some loss
of pollutants assumed for tight recycle due to byproduct contam-
ination, volatilization to the atmosphere in open cooling towers, and
development of corrosion products in the coke oven gas. distribution
system.
The environmental impact of these wastewater streams can be
summed up by considering the overall mass balance of emissions
to the air, water, and the land. The coke plant necessarily consists
of. coke ovens, the quench towers for the incandescent coke, the
byproduct plant, and an associated wastewater plant to treat the
wastes to meet the guidelines. FIgure 2 shows the principal plant
input, coal, and the main outputs of coke, coal chemicals, apd coke
oven gas. The mass balance must also include air emissions from
the open cooling tower and the quench tower in the form of vola-
tiles and particulate matter. Water emissions may be adequately
represented by ammonia, cyanide, and phenol. To control the
wastewater effluents to the degree required by current regulations,
a new element must be added—energy in the form of steam and
electricity is needed to operate the treatment systems.
51
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COAL
Energy for Wastewater Control—Alternative Strategies
The energy system is examined more closely in Figure 3. It con-
sists of a power plant, assumed to be a coal-fired boiler, to raise
steam and to generate electricity for the wastewater treatment
plant. The power plant also produces environmental emissions
even though the plant is configured to meet applicable air and
water regulations. Particulate matter, sulfur dioxide, nitrogen
oxides, and waste heat are emitted to the air. Waste heat goes to
the water; land emissions are ash and sulfur dioxide scrubber
sludge from the power plant, as well as demineralization or soften-
ing sludge from the boiler water treatment plant. An interesting
problem now arises. It appears that as one problem is solved—
the wastewater effluent problem from the coke plant—another
emission problem is created, namely the disposal of effluents pro-
duced from generatiqn of the required steam and electricity.
Furthermore, it seems’bbvious that more and more energy will be
required as the level’ of wastewater treatment becomes more
stringent. To decrease the effluents from the coke plant, one must
increase the effluents from the boiler plant. Several questions are
posed. Are we working at cross purposes? What is the net environ-
mental impact? How do we obtain an optimum level of wastewater
treatment which achieves the maximum environmental improve-
ment, considering all effects? To answer these questions, it is
necessary to perform a careful environmental assessment of the
coking operation, including an examination of alternative strate-
gies for handling the wastewaters. Table 3 lists eight alternative
strategies (Cases 0 through 7) for controlling wastewater dis-
charges. Each strategy involves one of three levels of wastewater
treatment (Raw wastewater, Level I, Level II), one of two levels
of recycle (LooSe, Tight) and one of two quenching practices
(Clean, Wastewater).
AIR E IUSSIONS
• QUENCH WATER
•COOLING TOWER VOLATILES
LAND SSIONS
• TREATMENT PLANT SLUDGE
- -
• PROCESS WASTEWATER$
Figure 2. Input and mean outputs of a coke plant.
52
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ELECTRICITY
C
(FUEL)
STEAM
COKE PLANT WASTEWATER
TREATMENT PLANT
ENERGY PLANT
LAND EMISS iONS
• ASH
• SLUDGE
WATER EMISSIONS
• WASTE HEAT
AIR EMISSIONS
•SO
•NOx
• PARTICULATE MATTER
• WASTE HEAT
Figure 3, Inputs and outputs of the energy system needed for the coke plant
TABLE 3. COKE PLANT WASTEWATER CONTROL
STRATEGIES
Level of recycle — — Type quench
Treatment Loose Tight Clean Vlastewater
0
1
2
3
Rawwastewater
Raw wastewater
X
X
‘
X
X
X
X
X
X
Raw wastewater
Raw wastewater
4
Levell
X
X
5
Level l
X
X
6
LevellI
X
X
7
Leve l l l
I C
X
WATER
BOILER WATER TREATMENT PLANT
UTiLiTY AND POWER PLANT
STEAM GENERATION
ELECTRI CITY GENERATION
Case
53
-------
Flow processes for the wastewater treatment strategies are
shown in Figures 4 and 5 for a hypothetical coke plant configured
for this study. The wastewater flows are generated from recovery
operations found in many steel plants. With a daily coal charge of
6000 tons (5443 kkg) and a daily furnace coke production of 4200
tons (3810 kkg), such a plant would be among the largest 25 plants
in the country. Level I treatment is wholly a physical-chemical
system employing a method for cyanide stripping based on existing
technology developed by Bethlehem Steel Corporation, 3 ammonia
removal using a conventional still, and phenol extraction based on
existing technology developed by Jones and Laughlin Steel Cor-
poration. 4 Level II is a higher level of treatment combining phys-
ical-chemical operations with biological waste treatment. The
CN
NH 3
PHENOL
FLOW
362 kg/day
3439
965
95 7 m 3 /day
CN
NH 3
PHENOL
FLOW
91% NH 3
40% CN
18 kg/day
3439
965
957 m 3 /day
CN
NH 3
PHENOL
FLOW
11 kg/day
310
965
1163 m 3 /day
CN 11 kg/day
NH3 310
PHENOL 77
FLOW 1(63 m 3 /day
CN 21 kg/day
NH 3 31$
PHENOL $2
FLOW 2063 mfday
Figure 4. Flow diagram for treatment level 1 for wastea from tight recycle.
54
-------
biologicaa plant is similar to an existing facility at Bethlehem Steel
and is designed to reduce the carbonaceous oxygen demand, with
performance primarily set for phenolics reduction. These tteat-
ment Systems do not precisely correspond to treatment levels
designed to meet cunej t EPA BPCTCA or BATEA limits. How-
ever, Level I meets BPCTCA guideliass for cyanide and ammonia;
Level I I meets BPCTCA guidelines and the BATEA guideline for
phe •
The eight different control strategies each result In pollutant
emissions to the air, wate r, and land. Air emissions originate from
CN 372 kg/day
NH 3 3447
PHENOL 970
FLOW 1857 m 3 /day
C M 19 kg/day
NH 3 3447
PHENOL 970
FLOW 1857 m 3 /day
91% NH 3
40% CN
CM
NH 3
PHENOL
FLOW
99.97%
PHENOL
50% CN
to NH 3
11 kg/day
310
970
2282 m 3 /day
CM
N ib
PHENOL
FLOW
5 kg/day
314
0.3
2282 m 3 /day
EFFLUENT
FIgure 5. Flow diagram for treatment level Il for wastes from tight recycle.
55
-------
1 04 r
io 3 l—
102
the coke quench tower, from the open cooling towers, and from
the power plant supplying electricity and/or steam to the treat-
ment process units. Water emissions arise from coke plant waste-
waters, from blast furnace wastewaters which account for pol-
lutants transferred by wastewater quenching, and from power
plant waste heat discharges. Land emissions originate at the power
plant, the quench tower, the boiler water treatment plant, the coke
plant ammonia still, and the coke plant biological treatment plant.
The foundation of the analysis is the construction of an inven-
tory of all principal pollutants emitted to air, water, and land for
each of the selected control strategies. Figure 6 shows the daily
AIR EMISSIONS
;io
‘a
a
04
S
UI
C
-J
-J
0 ____
° 1o2
10
1
— I I I I
0 1 2 3
CASE
o.i _____
CASE
Figure 6. EmissIons inventory for a 3,810
light selected strategies.
LAND EMISSIONS
SOrLIME SLUDGE
ND
COKE SIIEEZE
N UMESLu:E
BOILER WATER
SLUDGE
— I. I I I I I I I
0 1 2 3 4 5 B
CASE
kkg/day (4200 ton/day) coke plant for
CI
I I I I
4 5 B 1
P
56
-------
emissions for a selected list of pollutants from each of the active
operations for each control strategy. Measures were generated for
eight pollutants emitted to the air, six pollutants to the water, and
five pollutants to the land. By itself, this accounting of the residuals
shows the relative complexity of the problem. It remains for the
community and the regulatory agency to develop an aggregate
summation of these different residuals in order to select an overall
best strategy for the environment as a whole.
CROSS-MEDIA ANALYSIS
Comparing the complete inventory of emissions with the original
wastewater loads (Figure 6, Case 0) shows that the reduction of
emissions of ammonia, cyanide, and phenol to the water involves
the generation and discharge of many other pollutants and treat-
ment residuals to the air and land. A comparison of the relative
environmental impact of the different strategies demands the abil-
ity to compare trade-off effects, i.e., the effect on the environment
of reducing mass emissions of pollutants to the water while increas-
ing mass discharges of other pollutants to the air and land. Rei-
quam, Dee, and Choi at the Battelle Memorial Institute under a
contract sponsored by the Council on Environmental Quality and
the EPA developed a technique for this purpose, termed Cross-
Media Analysis. 5 This analysis starts with a mass emission inven-
tory. A hierarchical arrangement of weights is developed consisting
of two levels: media weights and pollutant weights. The first level
of weights for air, water, and land may be regional or applicable
to the country as a whole. The second level of pollutant weights
establishes a mechanism for allocating relative fractions of each
of the media weight totals to each pollutant. Choices between alter-
native strategies are based on the relative values of a numerical
index calculated from the Cross-Media Analysis.
The environmental degradation index (EDI) is the arithmetic
sum of the weighted damages for each pollutant in each media,
EDI =
where p is the pollutant index and
d , 5 is the damage function for a selected strategy, s, with
Ifl A Sj .
“ “P.S /,
M 9 is a modifier function which accounts for the dispersal and
persistence of the pollutant (0.1 M 0.8); and
W , is the weight assigned to the pollutant, p, relative to the
other pollutants (pW 1 , = 1000).
A large value of the EDI means a large expectation of environ-
mental degradation. Of course, the nature of the weighting scheme
does not permit one to interpret the number absolutely. However,
it is useful for comparing various control strategies. The algebraic
difference between (EDI),, for a base case strategy and the (EDI) 5
for some other strategy is defiz2ed as the strategy effectiveness
index (SEI)
(SET), = (EDI) 0 — (EDT) 0
57
-------
Values of SE I which are positive are interpreted as having a net
improvement over the base case, whereas negative values of the
SEI imply a net environmental degradation. This value of the SEI
is the final basis for comparing, ranking, and choosing between
control strategies.
This study used two sets of pollutant weights: one was based on
choices made by steel industry experts at Battelle Institute (3M!);
the second was selected by the authors (CMU) from a considera-
tion of several sets of national air and water quality criteria.° 7
Table 4 compares the relative weights. Both sets of choices assign
approximately the same emphasis to each media, with air and
water both ranked above the land. The CMU system distributes
the pollutant weights less evenly than does BMI and focuses on
phenol in water as being the most critical pollutant to control.
The mass emission inventory shown graphically in Figure 7
TABLE 4. POLLUTANT WEIGHTS (W 1 .) AND MODIFIER
FUNCTION (Mr) FOR COKE PLANT WASTEWATER STUDY
Pollutant
CMU weights
W M 1 , W 1 ,M
BMI
W
weights
M,, W M
To water:
NH 3 5 0.6 3 52 0.6 31
Phenol 321 0.5 160 84 0.5 42
CN 22 0.5 11 74 0.5 37
Thiocyanate 3 0.5 2 56 0.5 28
Cl 1 0.6 1 33 0.6 20
Heat 22 0.5 11 74 0.5 37
Sum 373
To land:
Ash, coke breeze 41 0.5 20 42 0.5 21
SQ-Lime sludge 54 0.6 32 58 0.6 35
NH Lime sludge 54 0.6 32 58 0.6 35
Boiler water sludge 54 0.6 32 58 0.6 35
Biological sludge 54 0.6 32 58 0.6 35
Sum
To air:
NO 30 0.5 15 22 0.5 11
SO 2 70 0.7 49 43 0.7 30
PM 60 0.8 48 56 0.8 45
NH 3 26 0.5 13 47 0.5 24
Phenol 48 0.4 19 56 0.4 22
CN 82 0.4 33 60 0.4 24
CI 25 0.4 10 47 0.4 19
Heat 30 0.5 15 22 0.5 11
Total 1000 1000
• •_ _ c • -r
58
-------
The damage function is assumed to be the cumulative
Beta Function based on two parameters, a and /3.
Mean of distribution is (a / (a + fi)] and the variance of
the distribution is [ afi / (a + /3)2 (a + / 3 + 1)].
For all cases, the damage function is 1 where the relative
emission is I, that Is, the actual emission is maximum.
When the actual emission is zero, the damage function is
zero.
The following ranges of a and $ were studied:
1
J.
F Igure 7. The damage function.
U )
I
i
0
C .)
LU
C ,
C
C
0
a
RELATIVE MASS EMISSION
59
-------
must be converted to a set of numbers between 0 and 1, to be
expressed as the damage function, d , for the Cross-Media Analysis.
This study examined the sensitivity of the EDI to the procedure
used for calculating damage. The simplest damage function imag-
inable scales damage as a linear function of the mass of pollutant
discharged. One may choose damage functions to scale relative
emissions nonlinearly, so as to place heavy damage on any small
emission or to delay assignment of damage until a large fraction
of the largest possible emission is reached (Figure 7). The results
of the sensitivity of the relative rank of the coke plant strategies
for nine damage functions are shown in Table 5. Using either the
CMU or the BMI weighting functions and the various damage
functions, the relative ranks of the coke plant wastewater strate-
gies are nearly the same. By comparing absolute values of the SE I
calculations as well as the sensitivity of the ranks for each strategy,
it is possible to assemble the qualitative grouping of the coke plant
strategies shown in Table 6.
TABLE 5. FREQUENCY DISTRIBUTION OF ALTERNATIVE
STRATEGIES BY RANK FOR NINE DAMAGE FUNCTION
CHOICES
Case
Tank
Average
1
2 3
4 5 6
7
8 rank
Number
of times case
ranked as shown
(CMTJ
weights)
0
X
I X
2 2 3
1
X 5.00
1
1
1 X
4 1 1
1
X 4.11
2
X
X X
1 5 3
X
X 5.22
3
6
1 X
2 X X
X
X 1.78
4
2
4 2
X 1 X
X
X 2.33
5
X
2 7
X X X
X
X 2.78
6
X
X X
X X 2
7
X 6.78
7
X
X X
X X X
X
9 8.00
Number
of times case
ranked as shown
(BMI
weights)
0
X
2 1
X 1 5
X
X 4.67
1
3
2 1
X 3 X
X
X 2.79
2
X
X 2
2 5 X
X
X 4.33
3
6
2 X
1 X X
X
X 1.56
4
X
X 1
4 X 4
X
X 4.78
5
X
3 4
2 X X
X
X 2.89
6
X
X X
XX X
X
9 8.00
7
X
X X
X X X
9
X 7.00
COMPARISON OF WASTEWATER CONTROL STRATEGIES
Table 7 shows that control of coke plant wastewaters does result
in environmental improvement for the watercourse to which the
60
-------
TABLE 6. GROUPING OF WASTEWATER TREATMENT
STRATEGIES
.
Qualitative
Case
Treatment
ranking
3
—
Raw wastewater effluent; tight recycle;
wastewater quench
Preferred
5
Level I treatment; tight recycle;
Preferred
wastewater quench
1
4
Raw wastewater effluent; loose recycle;
wastewater quench
Level I treatment; tight recycle; waste-
Better than
base case
water discharge to watercourse
2
Raw wastewater effluent; tight recycle;
0
wastewater discharge to watercourse
Raw wastewater effluent; loose recycle;
Base case
wastewater discharge to watercourse
6
Level II treatment; tight recycle;
7
wastewater discharge to watercourse
Level II treatment; tight recycle;
Not preferred
wastewater quench
TABLE 7. NET ENVIRONMENTAL IMPACT FOR TWO
SELECTED SETS OF POLLUTANT WEIGHTS AND A
S-SHAPED DAMAGE FUNCTION
___ (a = /3 = 1.5)
Case
Air Water
Land
Total
Rank
Strategy effectiveness
index
(CMU
weights)
0
0 0
0
0
5
1
—39 85
0
46
4
2
—5 3
0
—2
6
3
—75 172
0
97
1
4
5
—16 162
—30 170
—70
— ‘TO
76
70
2
3
6
—28 164
—148
—12
7
7
—39 166
—148
—21
8
Strategy effectiveness
index
(BMI
weights)
0
0 0
0
0
5
1
—47 77
0
30
2
2
—3 5
0
2
6
3
—89 154
0
65
1
4
—12 92
—76
4
4
5
—34 136
—76
26
3
6
—20 82
—161
—99
8
7
—40 120
—161
—81
7
61
-------
plant discharges its wastes. Control strategy Case 0 (loose recycle,
no wastewater treatment, discharge to the river) is chosen as the
base case against which all other strategies are compared. The least
desirable control strategies have negative SEI values, indicating
a net environmental damage when compared with that of the base
case. In contrast, a large positive total SE I value for a control
strategy indicates net environmental improvement when compared
with that of the base case. For all control strategies, and either
weighting method, positive SE I values occur for the water media,
indicating environmental improvement over the base case.
Note, however, that environmental improvement for the water-
course is coupled in every situation with degradation of the air
and land media. Values of zero for the SEI mean that these cases
are identical to the base case. Furthermore, in some cases the net
environmental degradation of the air and land media are large
enough to negate the improvement which has taken place in the
watercourse. Environmental improvement in one media—here,
water—is inextricably associated with deleterious cross-media ef-
fects, which may be large enough themselves to provide no net
environmental improvement for the control effort.
CONCLUSIONS
The principal findings of this study apply to the coke plant
problem in particular, but they suggest there may be grave conse-
quences whenever there is stringent effluent regulation for separate
media. Wastewater treatment provides environmental improvement
for one media, water, but will lead to. the degradation of the other
media, air and land. This is the phenomenon of cross-media impact;
energy requirements for treatment processes create new pollutant
residuals which are smeared acrOss all media. For some waste-
water treatment practices, the net environmental improvement
due to the practice is negative, i.e., cross-media effects are so large
as to, negate the beneficial effects of improving the water media.
The frequency for which net degradation of the environment is
forecast from this analysis depends on input parameter values and
assumptions; this frequency rises sharply with the stringency of
wastewater treatment.
It is useful to characterize the coke plant problem in three ways:
by type of quench water, by level of process water recycle, and by
level of treatment selected for wastewaters. The cross-media analy-
sis leads to the following observations:
1. Quenching with coke plant effluents, regardless of their level
of treatment, appears to be a preferred practice for the greatest
net improvement of the environment , This practice is preferred
to that of discharging effluent (at the same level of treatment) to
watercourse.
2. Tight recycle of cooling waters rather than loose recycle ap-
62
-------
pears to be preferred for the greatest net environmental improve-
ment.
3. For the wastewater control case in which tight recycle of
cooling waters is employed and the final effluent is used for waste-
water quenching, no wastewater treatment is a preferred practice
over either Level I or Level II treatment, if the greatest net en-
vironmental improvement is to be achieved.
4. For the wastewater control case in which tight recycle of
cooling waters is employed and the final effluent is discharged to
a watercourse, Level I is the preferred wastewater treatment if
the greatest net environmental improvement is to be realized.
For this case, this treatment level is preferred over the alternatives
of no treatment or Level U treatment.
5. These results suggest that the current EPA effluent standards
for by-product coke plants, particularly the BATEA (1983) limits,
are too stringent to maximize the net environmental improvement
which can resifit from the treatment and disposal of coke plant
Wastewaters
The results of this study clearly support the contention that
levels of environmental control must be considered very carefully
if maximum improvement of the environment is to take place;
stringent control of emissions is not necessarily the best course of
action. However, this analysis, like all analyses, is an approxima-
tion of reality, and not reality itself. In particular, the cross-media
technique requires many assumptions which are open to question
and interpretation. Nevertheless, the results of the study appear
robust enough that strong conclusions can be stated regarding
current by-product coke plant effluent limitations. This analysis is
offered not to exacerbate the current controversy regarding treat-
ment and disposal of coke plant wastewaters, but to move the
Controversy toward more rational emphasis on net improvement
of the environment, rather than emphasis on single media regula-
tions and solutions.
REFERENCES
1. U.S. Bureau of the Census, Statistical Abstract of the United States:
1973 (94th Edition), Washington, D.C., 1973.
2. “hon and Steel Manufacturing Point Source Category, Effluent Guide-
lines and Standards,” Federal Register, Vol. 39, No. 126, .Tune 28, 1974.
3. Kun , S. K., “Recovery and Utilization of Sulfur from Coke Oven Gas,”
In Problems and Control of Air Pollution, ed. by F. S. Mallette, Rein-
hold Publishing Corp., 1955.
4. Lauer, F., E. J. Littlewood, and 3. J. Butler, “New Solvent Extriction
Process for Recovery of Phenols from Coke Plant Aqueous Waste,”
Jones and Laughlin Steel Corporation. Presented at Eastern States Blast
Furnace and Coke Oven Association Meeting, Pittsburgh, Pa., February
14, 1969.
5. Relquam, H., N. Dee, and P. Chol, “Development of Cross-Media Evalua-
lion Meth Jology,” Final Report to Council on Environmental Quality
63
-------
and U.S. Environmental Protection Agency, Contract No. EQC3I5, Bat-
telle Memorial Institute, Columbus, 0. Vol. I and II , January 14, 1974
(PB232414/3WP); also “Assessing Cross-Media Impacts,” Environmentai
Science and Technology, Vol. 9, No. 2, February 1975.
6. Dunlap, R. W., and F. C. McMichael, “Environmental Impact of Coke
Plant Wastewater Treatment and Disposal,” Journal of Ironmaking and
Steelmaking, in press.
7. Dunlap, R. W., and F. C. McMichael, “Air, Land, or Water: The Dilemma
of Coke Plant Wastewater Disposal,” Environmental Science and Tech-
nology, in press.
64
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TANNERY WASTE MANAGEMENT
J. David Eye
ABSTRACT
Tanning of hides into leather creates large volumes of highly
polluted wastes. Initially most of the pollutants are contained in
relatively small-volume, highly concentrated waste fractions. Sep-
aration and pretreatment of waste fractions before blending for
clarification and biological treatment appears to be the most effi ..
cient method for managing these wastes.
Plant arrangement and discharge schedules often prevent effec-
tive separation of the waste fractions, hence it may be necessary
to treat the combined wastes as a single effluent. When separation
and pretreatment are possible, the usual procedure is to oxidize
the sulfides with air using manganese as a catalyst and to precipi-
tate chrome as chromium hydroxide. In some cases, flue gas is used
to lower the pH of the lime-bearing wastes.
The treatment of the combined waste streams usually includes:
screening, primary clarification with or without coagulants, aerobic
biological treatment by activated iludge or aerated lagoons or a
combination of aerated and nonaerated lagoons, final clarification,
and disinfection if required. Treatment efficiencies for BOD and
Suspended solids removal often are well above 90%.
The author has specialized in the in-plant removal of sulfides
and chrome and in the use of aerobic-anaerobic lagoon sjjstems for
final treatment. Design criteria and operating data from some of
the projects that he has designed and constructed are presented.
Operational problems, particularly those related to cold weather
Operation, are discussed.
INTRODUCTION
The tanning industry has long been recognized as a major con-
tributor to water pollution because of the highly pollutional nature
of the constituents of untreated tannery effluents. The total volume
of tannery wastes discharged in the United States, however,
amounts to only about 16 x 10° gal (6.056 x l0 m 8 ) per year, a
rather small volume when compared with the discharges from
many other wet industries.
There are two basic types of tanning in use in some 300 tanneries
65
-------
in the United States today—vegetable tanning and chrome tanning
or some combination thereof. Chrome tanning, used mainly for
producing side leather, accounts for 85 % to 90 % of the total pro-
duction, and vegetable tanning, which is used for heavy leathers,
accounts for only about 10 % to 15 % of the total. Domestic cattle
hides make up the bulk of raw materials used, with some 18 to 20
million being tanned annually. Sheep skins and pig skins are also
tanned but constitute only a small percentage of the total weight
of hide substance tanned.
The tanning of animal skins is accomplished by chemically and
mechanically removing all of the extraneous hide substance from
the collagen fibers, which then combine with chrome salts and/or
vegetable extracts to produce leather. The materials used in tan-
ning operations include water, sulfides, lime, ammonium sulfate,
sulfuric acid, chromium sulfate, vegetable extracts, sodium car-
bonate, detergents, natural and synthetic oils, dyes, filling agents
such as starch and clay, solvents, and a variety of organic finishes.
The tannery effluents therefore can be expected to contain various
amounts of all of the materials used in tanning plus the unwanted
hide substance extracted during tanning.
TANNING OPERATIONS
A large fraction of the hides that are tanned are received at the
tannery in salt- or brine-cured form. Only a small percentage of
the total number of hides tanned are processed from the fresh state.
The major tanning operations include: washing and soaking to
remove extraneous blood, manure, salt, and dirt and to restore
moisture to. brine-cured hides; hair removal with caustic (usually
lime) and sulfides (this step may only loosen the hair for mechanical
removal or it may be severe enough to completely dissolve the
hair); bating with enzymes and ammonium salts to remove excess
caustic and prepare the hides for tanning; fleshing to remove excess
fat and muscle tissue from the animal side of the hide (this may
be done before hair removal or afterward); splitting of the hide
into two or more layers (this may be done after hair removal or
after tanning); pickling or treating the bated hides with salt and
sulfuric acid; tanning with either vegetable extracts or chromium
salts; drying; shaving to achieve the desired thickness (weight);
buffing or sanding to smooth the surface; fat liquoring to restore
oils; coloring; and finishing ,
The sequence of operations varies in individual tanneries de-
pending on the end product desired. Also, some operations used
• for producing side leather are not required for heavy vegetable-
tanned leathers. The usual tanning steps are illustrated in Figure 1.
CHARACTERISTICS OF TANNERY WASTES
In cattle hide tanneries, the volume of wastes generated range
66
-------
- : 1
AL UIflIING
M u m
Fjure 1. Typical flow diagram for tanning.
VEWMU WC6SG
LEATHER
LEATHER
-------
from 100 to 1000 gal (0.3785 to 3.785 m ) per hide processed. Since
most tanning operations are of the batch type, the waste flow is
highly variable both in volume and in constituents during an
operating day. The fluctuations observed for one tannery effluent
are illustrated in Figure 2.
IS —
14 -
12 -
10
8
6
2
0
4
Wa
t
a
-a
I I I
6 8 10 12 2 4 6
PM AM
I I I
6 18 12 2 4 6
P s
U SC
Figure 2. Fluctuations in waste discharge from a tannery.
Detailed studies of tannery wastes by the author have revealed
that a large fraction of the pollutants of concern initially are con-
tained in relatively small-volume waste fractions. The large-volume
waste fractions normally are derived from rinsing operations, and
as such they contain relatively low concentrations of pollutants.
In fact, it has been found that 75% to 80 of the BOD and sus-
pended solids are derived from waste streams that constitute only
about 30% to 40% of the total tannery effluent volume. Values
listed in Table I for the wastes from a vegetable tannery unhairing
TABLE 1.
CHARACTERISTICS OF BEAMHOUSE
WASTE FRACTIONS
Waste fraction
Flow,
gpd*
COD,
mg/l
Suspended
solids, mg/i
pH
Wash water
25,000
2,100
1,300
6.8
Soak water
10,000
2,200
1,000
7.8
Lime water
10,000
11,900
30,300
12.3
Rinse water
20,000
2,500
4,900
12.3
Hair water
15,000
2,500
3,100
12.3
Fleshing water
5,000
3,600
3,100
12.3
Bate water
55,000
1,700
1,000
9 ,0
* Note: 1,000 gpd = 3.785 ma/day.
68
-------
system illustrate the wide variability in individual waste stream
characteristics.
Typical waste constituents and concentrations for the mixed
wastes from a side leather tannery are listed in Table 2.
TABLE 2. TYPICAL WASTE CHARACTERISTICS
Waste parameter
Concentration range, mg/l
pH
9.0- 12.0
BOD
2,000-3,000
COD
2,500 -4,000
TSS
2,000-3,000
TS
4,000-9,000
Cl
2 ,500-4,000
TKN
150- 250
NH:
80- 125
100- 250
Cr 1
100- 250
Oil and grease
100- 250
WASTE MANAGEMENT PROCEDURES
An efficient plan for the management of tannery wastes must
begin at the points of waste generation — the individual tanning
operations. Careful control of the amounts of water and processing
chemicals used can effectively reduce the cost and difficulty of
treating the residual waterborne pollutants. Likewise, changes in
processing equipment can be highly beneficial in reducing the
amount of water and chemicals cised. For example, during the past
5 years many tanners have substituted mechanical hide processors
for the traditional paddle vats and drums for unhairing and tan-
ning operations. This step alone can reduce water consumption
by as much as 50 ‘4 and at the same time effect significant reduc-
tions in the amount of chemicals used because of better contact
between the hides and the tanning solutions. The hide processors
also facilitate the separation of the waste fractions for pretreatment
and/or recovery.
Pretreatment of individual waste streams generally is applied
to the unhairing wastes and the spent chrome tan liquors. Since the
unhairing wastes initially contain most of the sulfides found in
tannery effluents, consideration should be given to oxidizing the
sulfides to a more stable form before these wastes are mixed with
other waste fractions. It has been found that the sulfides can be
eliminated completely by air oxidation with manganese as a cata-
lyst in 3 to 6 hr. The concentration of manganese used is usually
57 to 10% of the sulfide concentration. For example, if the sulfide
concentration is 5,000 mg/I as S, the manganese concentration
would be 250 to 500 mg/l as MN .
The efficiency of air oxidation can also be exemplified in terms
69
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of the oxygen transfer rates. In most biological oxidation systems,
an oxygen transfer rate of 2 to 4 lb/hr/hp (1.4 )< 10— to 2.8 X l0
kg/kg-cal) is observed. In a manganese-catalyzed sulfide reaction,
the oxygen transfer rate usually ranges from 25 to 65 lb/h/hp
1.8 x 10- to 4.6 X l0 kg. kg-cal). The portion of the total HOD
contributed by the sulfides therefore can be removed more effi-
ciently by air oxidation with manganese as a catalyst than through
biological oxidation.
It should be mentioned that the unhairing wastes can be
screened, refortifled, and reused directly, or the sulfides can be
expelled as H S and redissolved in a sodium hydroxide solution
for reuse. These two recovery methods are being used to a limited
extent at present. Considerable attention also is being given to the
extraction of the proteins from the unhairing wastes.
In most side leather tanneries only about 65 ‘/ to 75 % of the
chrome used actually remains in the leather. The remainder of the
chrome is discharged in the tannery wastes. While there is no
conclusive evidence that the chromium in the effluent interferes
with waste treatment processes, it does pose a problem in the
disposal of residual sludges derived from treatment processes.
By separating the spent tan liquors and raising the ph to 9.5 to
11.5, the chrome can be effectively precipitated in the hydroxide
form. Once precipitated, it can be redissolved and reused in pre-
paring fresh tanning solutions. In some tanneries, the spent chrome
liquor is collected, refortified and reused directly for tanning.
Irrespective of the separation, pretreatment and/or reuse prac-
tices used, all of the tannery wastes must be screened before further
treatment. Several types of screens are in use, and all have certain
limitations and/or operational problems. The most frequent prob-
lem encoUntered is that of clogging with grease and chemical
deposits, and frequent or continuous cleaning usually is required.
Following screening, the wastes can be clarified to remove the
settleable solids. The use of inorganic coagulants and organic poly-
electrolytes enhances the settling process and ultimately improves
the dewatering characteristics of the sludge. In general, clarifica-
tion can be expected to remove 50’ 4 to 60 % of the BOD and as
much as 90 4 of the suspended solids. The settling characteristics
and the effectiveness of clarification on the unhairing wastes from
a vegetable tannery are illustrated in Figures 3 and 4.
The sludge derived from clarification is large in volume, has a
high moisture content (90 (4 to 95 ¶/ ), and is often difficult to de-
water. Pressure filters, vacuum filters, centrifuges and sand drying
beds are commonly used to dewater the sludge to a moisture con-
tent of 55 ‘/ to 80 %. Dewatered tannery sludges normally are
placed in landfill, although considerable interest is being shown
in agricultural applications. The dewatering characteristics on a
sand bed of the sludge derived from clarification of the unhairing
wastes from a vegetable tannery are indicated in Table 3.
70
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WASTE WITHOUT POLEELECTROLYTE
F
a
7
7
C
S
9
1 •
U. •
0
0
0 0 g 0
- I
— 0
0
0 0
— — 0 C s
S
0
p SUSPENDED SOLIDS 0 0
0 600
0
— — — —o TOTAL ALKALIN1T0 0 0
0
POLVELECTROLYTE DOSAGE, 8-13 mg/I 0 0
0
0 200 400 600 6 00 1000 1200 1400 1600
OVERFLOW RATE. gpd/1t 2
Figure 4. Suspended solids and total alkalinity removal versus overflow rate.
Note: 1 gpd/fP = 4.1 x 10-2 mlday per m 2 .
TABLE 3. SLUDGE DRYING CHARACTERISTICS*
Time,
Depth of sludge on
bed, in.
Weather
days
No. INo.
2
No.
3No.
4
Type
Temperature
0 •
2 4
6
8
Clear
25F(—4C)
1
¾ ½
1¼
2
Cloudy
28F(—2C)
2
¼ ½
1¼
2
Snow
22F(—6C)
* Sludge derived from unhairing wastes treated with
anionic po lyelectrolyte. Note: 1 in. = 2.54 cm.
5 to 10 mg/i of
60
60 —
40
20 —
A
10 mg /I POLVELECTROLYTE
0 6 16 24 32 40 40 55
SETTLING TIME, minutes
Figure 3. Settling characteristics of lime-bearing wastes.
100 —
71
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The clarified tannery wastes are amenable to aerobic and an-
aerobic biological treatment. Activated sludge systems, oxidation
ditches, and aerated lagoons are being used successfully to oxidize
the organic matter in tannery effluents. Tannery wastes normally
have a high organic nitrogen content and a relatively iow concen-
tration of phosphorous. Adjustment of the nutrient balance there-
fore may be required for optimum biological oxidation. A detention
time of 12 to 24 hr and a sludge age of about 5 days appear to be
necessary for activated sludge.
Effluent BOD values as low as 10 to 20 mg/I can be achieved
routinely with any of the aerobic biological systems during warm
weather, provided the final clarifier is properly designed and oper-
ated. When the waste temperature drops below about 15 C, treat-
ment efficiency is usually reduced, particularly in aerated lagoons
where the ratio of BOD to active biomass is high. Activated sludge
units and oxidation ditches are not as sensitive to low temperatures
as are the aerated lagoons because it is possible to maintain a lower
BOD to biomass ratio.
The author has specialized in the use of aerobic-anaerobic lagoon
systems for treating tannery wastes. In some of the systems, ex-
ensive separation and pretreatment of waste streams are carried
out before biological oxidation; in others, the total wastes are only
screened and clarified before being admitted to the lagoon system.
The lagoon systems normally utilized consist of stratified aerobic-
anaerobic units in series with anaerobic lagoons,-tr aerobic units
in series with anaerobic lagoons.
One such system designed for a tannery in New England is
illustrated in Figure 5. The wastes are screened then allowed to
flow through a large lagoon where the settleable solids are removed
Figure 5. Lagoon system designed for a New England tannery.
72
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by settling. The pH of the sludge lagoon is maintained above 11.0
at all times to eliminate odors. The accumulated sludge is not
removed, hence this lagoon will ultimately have to be abandoned.
Initial calculations indicated that the sludge lagoon would have
a useful life of 15 years, but recent surveys indicate it will be
useful for at least 20 years.
The design criteria for the system are listed in Table 4.
The expected performance of the system in terms of effluent
BOD values is outlined in Table 5.
TABLE 4. DESIGN CRITERIA FOR A 0.60-MGD TANNERY*
Constituent — mg/I lb/day
BOD —5 day, 20°C
screened waste 1,500 7,500
BOD —5 day, 20°C
settled waste 1,000 5,000
Suspended solids 1,900 9,500
Suspended solids after
settling 500 2,500
COD 3,000 15,000
NH;, nitrogen 50 250
90 450
*
Note: 1 lb = 0.453 kg.
TABLE 5. EXPECTED PERFORMANCE OF SYSTEM
Item Amount
ROD of total waste 1,850 mgi
BOD of clarified waste 1,000 mgi
BOD of final effluent (summer) 100 mgi
BOD of final effluent (winter) 250 mg I
BOD to receiving stream (summer).... 500 lb/day
BODto receiving stream (winter) - 1,250 lb/day
Lagoon Numbers 2, 3, 4, and S provided detention times of 3, 3,
30, and 2 days, respectively, at the design rate of flow. Initially it
was assumed that Lagoon Numbers 2, 3, and 4 would be operated
as stratified aerobic-anaerobic units and Number 5 as an anaerobic
lagoon. It was necessary therefore to estimate the distribution of
the BOD among the lagoons so that adequate aeration capacity
could be provided.
Since the tannery operated only 5 days each week, there was
little flow on 2 days. The BOD derived from each operating day
would therefore affect each lagoon differently. Laboratory studies
showed that the ultimate BOD was exerted in about 20 days;
hence, the BOD for each day for a 20-day period was routed
through the lagoons by assuming that plug flow pertained. The
routing procedure is illustrated in Figure 6.
73
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DAY
—
L.AGOON
T
W
T
F
S
S
M
I
—
W
T
—
F
—
S
—
S
—
M
—
I
—
W
—
I
—
F
—
S
—
S
—
M
I
W
M
0
N
— —.
T
S
-
No.2
No. 3
No. 4
No.2
No. 3
No. 4
- - -
—
1
—
—
2
—
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3
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4/2
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—
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-.
4/2
6
6
7
8
9/2
—
- —,
9/2
—
10
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11
—
12
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13
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14
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15
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16
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11
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18
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19
—
20
—
—
1
—
2
—
3
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4/2
— —
—
4/2
5
6
7
8
9/2
—
—
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- -
—
9/2
—
10
—
11
—
12
—
13
—
14
—
15
—
16
—
17
—
18
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19
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20
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E
0
- -
1
H
U
R
No.2
No.3
No. 4
- - - -
No.2
No.3
-
- -
1
2
3
4
5
6/2
- -
.
—
- -
—
—
1
—
—
2
—
—
3
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6/2
—
5
7
6f2
8
-
9/2
—
10
—
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Ii
—
—
12
—
—
13
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14
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16
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17
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18
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19
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.____
7
8
9’2
—
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--
F
a
No. 4
No. 2
No 3
No.4
9/2
10
11
12
13
¶4
15
16
17
18
19
20
-
—
I 1
—
2
—
—
3
—
—
4
—
—
5
—
-
—
7
—
8
—
9
—
10
—
11/2
11(2
12
—
13
—
14
—
15
—
16
—
17
—
18
—
19
—
—.
Figure 6. Exertion of BOD in lagoons 2, 3, and 4. Note: The numerical values
represent the progression of the 800 to the lagoons from 0 to 20 days
for a 5-day plant operating schedule.
-------
The BOD loadings calculated for Lagoon Numbers 2, 3, and 4
are listed in Table 6.
TABLE 6. BOD EXERTED IN LB/DAY/LAGOONS
Day Lagoon No. 2 Lagoon No. 3 Lagoon Nc 4
Monday 3,700 950 850
Tuesday 4,050 975 915
Wednesday 4,200 975 1,000
Thursday 4,225 1,050 1,065
Friday 4,275 1,150 1,135
Saturday 2,050 1,100 1,330
Sunday 1,600 975 1 ,130
Total _______ 24,100 7,175 7,425
* Note: 1 lb = 0.453 kg. — —
Floating aerators were selected for this installation. It was as-
sumed that the oxygen transfer capability of the aerators to tan-
nery wastes would be 2 lb/hr/hp (1.4 X 10 kg/kg-cal). On this
basis, 90, 25, and 28 hp were required for Lagoon Numbers 2, 3, and
4, respectively (I hp= 1.068 X 10 kg-cal/mm).
When the system was placed in operation, Lagoon Numbers 2, 3,
and 5 were aerated, and Number 4 was allowed to function as a
facultative lagoon. The results obtained during 21 months of opera-
tion are presented in Table 7.
The accumulated data show that the system gave a higher degree
of treatment than was expected during the warm months of the
year. When the temperature of the wastes fell below 10 C, treat-
ment efficiency declined significantly with some observed values
exceeding design expectations. Part of the reduction in treatment
efficiency can be attributed to the poorer settling experienced when
the viscosity of the wastes increased with decreasing temperature.
Since no provision was made for sludge recycling this reduction
in treatment efficiency could not be counteracted because no in-
creased biomass concentration in the aerated lagoons could be
effected.
The reduction in the total Kjeldahl nitrogen (TKN) is of interest,
particularly with respect to the organic nitrogen fraction of the
TKN. Even during the winter months, most of the organic nitrogen
was removed either through precipitation or denitrification. The
nitrate concentration in the effluent never was observed above a
few mg/i. The chromium content likewise remained at low levels
for the entire period.
The major operational problems encountered have been those
caused by extremely low air temperatures. If an aerator stops
running for more than a few minutes, the wastes will freeze and
the aerator usually cannot be restarted until the ice thaws in late
spring. A major power failure during the winter months therefore
could completely eliminate the aerated phases of this system. For-
75
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TABLE 7. FINAL EFFLUENT CHARACTERISTCS
______________ ____ (mg/i)
Sample
date BOD TS TKN NH 1 Cr Grease
5/17/73 76 108 45 18 3.5 26
6/22/73 18 35 48 37 1.0 21
7/17/73 11 14 43 35 0.8 9
8/1/73 11 8 28 26 0.5 9
8/15/73 10 13 27 25 0.7 16
9/5/73 15 25 35 30 0.8 8
9/19/73 14 16 34 31 0.6 57
10/3/73 18 6 33 30 0.4 26
10/25/73 20 20 47 36 0.7 19
11/2/73 18 34 54 43 0.9 73
11/28/73 38 55 56 42 1 ,3 72
12/12/73 61 61 57 39 3.7 72
12/26/73 118 10 47 27 1.7 28
1/14/74 168 10 56 29 0.7 5
1/28/74 241 7 97 35 1.1 13
2/13/74 258 12 48 43 3.0 10
2/28/74 361 68 62 36 5.4 289
3/14/74 324 96 33 27 4.2 21
3/28/74 333 166 44 35 4.6 36
4/17/74 238 85 36 32 2.0 49
4/30/74 146 524 34 27 4.0 —
5/15/74 110 181 40 33 3.5 96
6/6/74 56 71 45 39 1.8 42
6/27/74 16 95 50 47 1.0 54
7/16/74 28 24 42 40 1.0 29
7/30/74 14 268 35 34 0.8 10
8/19/74 12 63 36 34 0.2 30
8/29/74 19 4 44 42 0.5 130
9/17/74 16 18 54 52 0.8 30
10/1/74 13 27 55 53 0.9 70
10/15/74 18 122 54 52 0.5 120
10/31/74 35 308 54 51 0.8 230
11/15/74 12 48 54 50 1.0 70
11/21/74 46 249 53 49 1.8 180
12/17/74 76 73 48 42 2.0 60
12/31/74 176 125 50 43 2.0 30
1/15/75 222 774 42 34 2.0 30
tunately this has not happened in the 3 years that this system has
been operating.
It must be emphasized that the system design was based on water
quality standards in existence in 1971. The system will not meet
current EPA effluent guidelines during the winter months, and
extensive revisions will be effected during 1976.
76
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DEVELOPING TREATMENT FOR TEXTILE WASTES
Jan Suschka
ABSTRACT
A variety of methods can be used for treating combined munici-
pal and textile wastewater. Results presented here show that chem-
ical treatment, although effective for pollutant and especially for
color removal, requires large amounts of chemicals. The use of lime
without any additional chemicals can be recommended. Complete
color removal does not normally take place by coagulation and
must be achieved by activated carbon adsorption.
Another approach using two-stage biological treatment was also
shown to be effective. Good removal of organic pollutants and color
can be obtained when an anaerobic fixed-bed filter followed by an
activated sludge process is applied. But, as in the case of chemical
treatment, total removal of color requires the additional step of
activated carbon adsorption.
Development of the textile industry has included the use of many
new methods and agents for fiber dyeing. The present list contains
3500 dyes—more than 2000 of them azoic dyes. Treatment of textile
dye house effluent has therefore been a long and difficult problem.
The open literature contains many studies concerning the prob-
lem of treating textile wastewater by physical, chemical, and bio-
logical methods. The suitability of a method depends very much on
the type and concentration of constituents in treated wastewaters.
At present, no universal procedure can be recommended; but re-
sults of research can point to possible solutions and help with
specific problems.
BIOLOGICAL TREATMENT OF TEXTILE WASTEWATERS
Activated sludge treatment of combined municipal and textile
wastewater was reported by many authors to be an effective
method, but the problem of color removal is controversial. Color
removal rates with this method range from 0 % to 99 % because
of the variety of dyes used by the textile industry and their vary-
ing resistance to biological degradation.
To investigate the suitability of various color removal methods,
sewage was mixed with a prepared solution of dyes, detergents,
7 ?
-------
and aids. The basic test mixture used for the first runs (Series I)
is given in Table 1. Subsequent test runs (Series II) were carried
out with a 0.1’ dye bath/wastewater mixture (Table 2).
TABLE 1. COMPOSITION OF WASTEWATER USED IN
TESTING THE ACTIVATED SLUDGE METHOlI SERIES I
Components added to settled Concentration,
____________ municipal sludge___ ____ mg ‘1
Reactive dye — lunasol red SB 50
Basic dye — aniline red BLN 50
Sulphur dye sulphur brown 50
Welan dye — Welan brown 50
Dispersant NNO 50
Fixative WOM 50
Total 300
TABLE 2. COMPOSITION OF THE 0.1 7. DYE BATH/
WASTEWATER MIXTURE, SERIES II
Components added to settled Components concentra-
municipal sewage tion, mg/i
Dyes:
Aniline red BLN 4.17
Lunasol red 5B 5.00
Sulphur brown 3.34
Welan brown 6.67
Total 19.18
Assistants:
Dispersant NNO 2.00
Elanofor 0.33
Lodegal MK 1.67
Rokaphenol N 8 0.66
Suphurol N2 0.08
Fixative WOM 6.67
Total 11.41
Acetic acid 10.0
Sodium sulphide 8.35
Sodium carbonate 8.35
Sodium sulphate 8.00
Laboratory-scale investigations were carried out in 5.71-liter
aeration tanks aerated with surface rotors. The average BOD of the
investigated mixture was 145 and 210 mg/l, respectively, in Series
I and U. With a mixed volatile suspended solids content in the
aeration tank on the order of 1 to 2 g/l and a detention time of
4.5 to 6.1 hr, the load of BOD was in the range of 0.20 to 0.95
78
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g BOD/g MLVSS/day. The respective load of COD determined
from filtered samples ranged from 0.25 to 1.35 g/g/day.
The removal efficiency of BOD and COD was given in Figure 1.
By presenting the results of BOD removal as a relationship of the
rate of removal (W) and the activated sludge load (L) (Figure 2),
a mathematical expression can be given:
L
W_ 2 2 2 +t
where: W = BOD removal rate, d-’
L = activated sludge load, g/g per day
With a relatively high BOD removal rate of 60% to 90 % (Figure
1), no color removal (or ocassionally only a 2070 rate) was
obtained.
100-
50
- __I__ I t I i i
0.5 1.0 1.5
ACTIVATED SLUDGE LOAD. gig MLVSS dey
Figure 1. Relationship between BOO and COD removal and sludge loading.
On the basis of batch tests for each individual dye in admixture
to sewage, it was shown that all four tested dyes were similarly
resistant to biodegradation. A maximum removal rate of 5 % was
achieved for the reactive dye, lunasol red SB. The dye Welan brown
was removed to a similar degree. Higher color removal up to 10 %
was obtained for the sulphur dye (sulphur-brown). The highest
removal rate, from 10% to 20%, was obtained for the basic dye,
aniline red BLN.
All of the dyes as well as the dispersant NNO and fixative WOM
were tested in an admixture with sewage, using a concentration of
300 mg/l. With such high concentrations of these compounds, very
good BOD removal rates (50% to 86%) were achieved. Thus any
A
a
Series BOO COD
1 £ £
2 S 0
I • . I
79
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6—
5—
w
z
0
‘C
0
-J
L U 4
0
0
-J
I4.
0
- a 3
‘ C
0
C
0 -
0
L U
1—
I I . 1 I I
1 2 3 4 5
BOD REMOVAL RATE
Figure 2. Efficiency of the activated sludge process.
toxic effect of these compounds could be noted. However, COD
removal was only 20 0/ to 35 % for all compounds except the dis-
persant NNO, for which a 10 X COD removal was obtained.
Distinct improvement of color and removal of other organic
substances (expressed as BOD or COD) were shown to be possible
with the use of a two-stage biological process. In the first stage,
an anaerobic fixed-bed filter was used. The anaerobic filter was fol-
lowed by an activated sludge process (Figure 3). During a 6-month
period of investigation, very similar treatment effects were ob-
tained. In Figure 4, an! example of BOD and COD concentration of
the influent and effluent from the anaerobic filter and aeration
tank is shown. With a COD removal rate of about 377 from the
anaerobic filter, the overall removal rate was about 80 % in the
two stages.
The most important result of treatment was the high color re-
moval rate. When the influent color was said to be 100 7, the
effluent from the anaerobic filter ranged from 70 ‘4. to 867 , and
the effluent from the aerobic stage was 20 % to 40 %. On the aver-
.
.
L
W :2
2.2+1
80
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ANAEROBIC FILTER
AERAIIIII
Figure 3. Scheme of the experimental units.
age, about a 257 color reduction was obtained during the an-
aerobic stage, but total color reduction was as high as 707
(Figure 5).
The anaerobic process used as the first stage resulted in structure
changes of at least sOme dyes present in the mixture. To confirm
these changes in dyb structure, spectrograms in infrared and ultra-
violet were done.
The use of an anaerobic filter as the first stage of biological treat-
ment also results in an effective nitrification process in the acti-
vated sludge process. The anaerobic process leads to a distinct
increase in the ammonia nitrogen content. The activated sludge
process then resulted in nitrification of about 75% of the ammonia
nitrogen to nitrates.
CHEMICAL TREATMENT
Effective treatment of combined municipal and textile waste-
waters can be performed by the coagulation process. Chemical
addition results primarily in high color and turbidity removal.
Relatively good color removal can be obtained with simple lime
addition. The effects of color removal vary with the concentration
of dyes in the solution and the rate of added lime. Observations of
0.1% and 3.0% dye solutions in municipal sewage are pre-
sented in Figure 6. The characteristics of the sewage also seem to
RAW WASTE WATERS
81
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300.
COD (total)
______ • 127
—
. •
SUBSEQUENT DAYS
Figure 4. Removal of organic substances in the two-stage biological treatment
process.
£ influent
• anaerobic filter effluent
• activated sludge effluent
____-a —e
120
a a
SOD
_________ 244
£
U
COD (Irliered)
£
A
S
250.
200.
150.
100.
50.
U
—
a
193
122
40
S
-U—
.
•
S
•
S
I . . .
25 30
I . . . . I
25 30
U U
— 38
.— — __ •
S
25 30
-------
90 —
S
C
C
0
-J
0
C-)
80
70
50
50
40
30
20
10
Figure 5. Color removal rate
U
— a — a a a a a a —e a a a ac a aaaaa a a as a V. 75
a a
— nas a e..a ne c a a —en ace aeaea av. 30
a
• activated sludge
• anaerobic filter
___ I a
25
SUBSEOUENT DAYS
in the two-stage biological process.
30
100
80
.J 60
C
0
‘U
04Q
20
CONCENTRATION OF DYE STUFF SOLUTION. %
Figures. Effects if lime addition (milligrams CaO per cubic decimeter) on color
a
0.1
.
83
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have definite effects on the removal rate of the impurities. For
example, data on color removal with the addition of 300 and 1000
mg/i CaO, given in Figure 7, are much higher than those presented
in Figure 6. However, to be on the safe side, lime should be added
in amounts of 4 to 10 g/l of CaO.
Figures 7 and B show that only large amounts of chemicals can
assure high rates of color removal. As with lime, additions of
copperas or alum does not improve the removal efficiency. An ex-
ception is the saturation with CO 2 after lime addition and sludge
removal. The advantages of that procedure are not only color
removal, but also an effluent pH close to 7. The coagulation process
results in a reasonable removal rate of COD—b ‘/ to 50 4 . But
a side effect of the process is the production of relatively large
quantities of sludge. About 4 kg/m of sludge with an average
water content of 90’/ is produced. Depending on the wastewater
flow to be treated, the sludge disposal problem can create a severe
problem. When the process of recalcination is introduced, the
sludge problem can be somewhat diminished.
ADSORPTION
Final removal of pollutants can be performed with the use of
activated carbon. The use of the adsorption process for color re-
moval has a long history, and thus much research has been done.
Although some rules are well known, investigations are necessary
in each specific case to obtain information on the capacity and
kinetics of substance removal by activated carbon.
To get comparable results and characteristics, the adsorption
capacity of powdered activated carbon was obtained for phenol
in a 0.1 % solution. The adsorption isotherm for phenol is given
in Figure 9. Instead of phenol, COD determinations were per-
formed to obtain comparable data on dye removal from prepared
solutions. The determined capacity was about 160 mg phenol/g of
activated carbon, Adsorption isotherms for seven different dye
solutions are also given in Figure 9. Adsorption characteristics for
the metals complex and basic dyes were similar to phenol. Rela-
tively good adsorption was also noted for the reactive and acid-
chromic dyes. The use of activated carbon as the final polishing
stage after chemical precipitation provided total color removal.
With color removal for the coagulation process in the range of
70 % to 90 ¶4, an effective color removal through adsorption still
requires about 1.5 g of powdered activated carbon per liter, with a
minimum retention time of 30 mm. It was interesting to learn that
activated carbon capacity differed with the chemical used for
coagulation (see Figure 10). The fine, unsettled suspension that
remained after a 2-hr sedimentation period was probably respon-
sible for this effect. Therefore, it is important to have a prefiltration
step in advance of activated carbon.
84
-------
g
Figure 7. Color removed by different chemicals.
0.1% DYE SOLUTION
II
05% DYE SOLUTION
S
I
3.0% DYE SOLUTION
I.
S
SI IS
100.
\‘h’ JY g ’ C ,,
ft ty $t
F ,
/ F ’,
Figure 8. Color removed by different chemicats.
85
r
-------
7
6
50 100 500 1,000
RESIDUAL CONCENtRATION, mg/I
5.000
Figure 9. Adsorption isotherm. COD removal from phenol and dye solutions.
Note: 1, phenol, 0.1%; metallic complex dye; basic dye; reactive dye;
direct dye; suspended dye; and sulphuric dye.
500 —
U,
a,
E
C
L u
C
U )
C
C
1-
2
C
C
50
5 10 50 100
RESIDUAL CONCENTRATION, mg/I
Figure 10. Adsqrption isotherm. Color removal from chemically treated waste.
waters. Note: 1, after coagulation by A1JS0 4 1 4 ; 2, after coagulation by
FeSO 4 ; 3, after coagulation by CaO.
1,000
500’
a,
E
C
L u
I50
10
10
It iiil
i i i I ti ii i LI I I I
1
100
1
I I IIflfll
I I I 1 _ i itil
86
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TEXTILE WASTEWATER TREATMENT METHODS
SUITABLE FOR RECOVERY
John J. Porter
ABSTRACT
The treatment of textile wastewater today is accomplished pre-
dominantly by biological waste treatment systems. This method of
treatment is successful when the waste is biodegradable, as is the
case with domestic wastewater. Since many industrial chemicals
are resistant to biological degradation and have significant value,
it may be better to use a waste treatment system that recovers
these chemicals for reuse in the plant. A comparison of biological,
chemical, and physical treatment methods is made, and the com-
bination of these systems into a waste recovery process is presented.
Reverse osmosis can play an important role in the recovery of
chemicals, water, and energy.
When a waste treatment plant was designed and built in the
past, it was assumed that it would adequately handle the waste
stream with no more than minor revisions for some years to come.
Today this assumption may not be entirely valid as far as con-
ventional waste treatment plants are concerned.
The public is becoming increasingly aware of the known prob-
lems that pollution can cause, and they are apprehensive about
unknown problems that have not yet been identified. Both of these
factors have caused the enactment of new laws and regulations
that have placed higher standards on outfall waters that enter
natural streams.
In 1972, Public Law 92-500 was passed.’ The objective of the
“Act” is to restore and maintain the chemical, physical, and bio-
logical integrity of the Nation’s waters. A national goal was set
to eliminate the discharge of pollutants into navigable waters by
1985. A national policy was set to prohibit the discharge of toxic
pollutants in toxic amounts.
With such regulations, it is no wonder that manufacturers are
hesitant to install waste treatment systems that are obsolete before
they are built. The comparison of waste treatment processes such
as biological treatment, carbon adsorption, reverse osmosis, and
chemical coagulation will be presented, and the integration of all
87
-------
WundaMcCor- Granite- Green- Springs
Constituent* Weve mick
Mills Bishop
COD 8,871 2,596
Filtered COD 7,942 2,487
TOC 4,140 1,606
HOD 5 3,745 860
HOD 1 O 4,800 925
HOD 15 4,450 1,175
HOD 20 4,700 1,100
HOD. 30 3,000 450
Solids:
Total 3,760 5,028 10,028 9,870 8,702 4,334
Dissolved 3,000 4,803 9,853 9,785 8,347 4,106
Suspended 760 225 175 85 355 228
Volatile 2,030 2,104 4,050 1,254 5,074 1,714
pH 6.7 6.0 6.6 6.8 7.0 5.0
Color (Pt-Co units) 1,250 1,000 12,044 2,618 5,618 1,826
Turbidity (FTU) 43 3 opaque 0.38 opaque 15
Conductivity 2,000 3,900 9,000 9,600 5,000 4,000
Alkalinity 140 456 587 182 341 65
Hardness 32 57 74 135 75 97
Ammonia nitrogen 24 5 3 3 4 12
Total Kjeldahl nitrogen 25 11 6 6 10 14
Phosphorus 160 4.2 15 6 41 3.0
Phenols 1.0 0.40 0.52 0.1 0.1 0.1
Metals:
Calcium 2.4 4.0 2.1 5.9 3.7 8.5
Chromium 0.13 0.19 8.1 3.1 1.4
Copper 0 ,2 1.2 8.6 0.64 0.66 6.2
Iron 1.3 1.3 10.3 12.0 7.0 2.9
Magnesium 1.0 6.0 12.0 13.0 24.0
Manganese 0.53 0.08 0.28 0.4 1.8 0.27
Mercury (ppb) 6.0 5.5 6.0 1.0
Nickel 0.33 0.17 1.2 1.9 0.1 0.56
Zinc 2.9 3.4 5.2 5.0 3.0 20.0
(except pi :
processes into a design most likely to give zero discharge will be
proposed.
BIOLOGICAL TREATMENT
Biological treatment of an industrial waste stream is successful
if the waste stream is biodegradable. Sometimes the waste stream
may be very biodegradable, other times it is not. The characteristics
of six different textile waste streams are presented in Table 1.
TABLE 1. CHARACTERIZATION OF CONCENTRATED
WASTE FROM SIX TEXTILE WASTE STREAMS
ville
2,500 3,720 15,285
935 1,410 5,753
270 1,078 1,547
415 1,600 2,200
515 1,800 3,500
560 1,600 4,500
820 2,200 5,000
wood
4,032
707
561
300
475
700
425
Uniess otherwije indicated, all units are in mg/i (ppm)
88
-------
These are waste concentrates taken from a pilot study of reverse
osmosis conducted for the South Carolina Textile Manufacturers
Association by Clemson University. The results of biological treat-
ment are presented in Table 2. These results may be compared to
general removal efficiencies of different treatment methods shown
in Table 3.
It is evident that when the BOD. after treatment is compared to
the COD (complete chemical oxidation), approximately two-thirds
of the waste is degraded biologically in a 10-day retention system.
The remaining portion of chemical constituents may be removed
with the sludge in an activated sludge treatment, or pass through
the plant untreated. The total removal of chemical constituents
from the waste stream by a biological process is 66 (,% This rate is
very good as biological processes go, but it is hardly good enough
to meet the zero discharge required by Public Law 92-500 in 1985.
These data were obtained from a laboratory waste treatment
system operating with a 10-day retention time in a mixed reactor
(Figure 1). Nutrients, flow, activated sludge temperature, and dis-
solved oxygen are carefully monitored. A full-scale waste treat-
ment system such as this should cost 50 4 to 7Oçh per 1000 gallons
to install, but as the data in Table 2 show, it would remove only
20 ‘4 of the color-bearing constituents in the waste stream.
It seems reasonable to expect that conventional biological treat-
ment as we know it today will not meet 1985 zero discharge re-
quirements if they are enforced.
CHEMICAL TREATMENT
Coagulation
The use of chemicals to treat industrial waste can be very suc-
cessful when they are used on specific waste streams. Pigments,
latexes, phosphates, and many other suspended materials can be
removed from industrial waste by simple coagulation. The coagu-
lating chemicals that are used include alum, iron chloride, lime,
and many organic polymers. 2 The preferred techniques vary and
depend on the waste.
Temperature, pH, and total dissolved solids all affect the success
of the treatment. If a waste stream requires specific coagulating
conditions in the laboratory to obtain satisfactory results, coagula-
tion may have limited success in plant operation if the conditions
of the stream are constantly changing. For this reason equalization
basins at the start of waste treatment plants may be necessary.
The equalization basin will normalize the composition of the waste
stream, and, if required, allow treatment chemicals time to react
to give more stable sludges for separation. The design engineer
may not appreciate the time it takes for lime or alum to completely
react and form stable precipitates. It is very important that the
sludge be stabilized if it is to be subsequently dewatered or ag-
glomerated with organic polymers. 3
89
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TABLE 2.
A SUMMARY OF OVERALL BEST RESULTS FOR TREATMENT METHODS
Wunda Weve
Before After
McCormick
Before After
Graniteville
Before After
Greenwood
Before After
Springs Mills
Before After
Bishopville
Before After
Overall Av,
% RemovalS
Before After
Item
carbon carbon
carbon carbon
carbon carbon
carbon carbon
carbon carbon
carbon carbon
carbon carbon
Biological study: *
¶7c BOD 5 removal
85.9 97.4
89.0 92.0
39.0 36.2
95.2 99.1
98.3 99.3
97.2 95.4
84.1 86.5
5’ - COD removal
43.7 72.4
59.7 62.5
28.7 35.1
33.3 88.0
64.8 65.7
64.0 62.7
57.3 64.4
¶4- color removalt
16.4 56.4
0 0
0 0
27.0 51.3
75.2 75,7
0 0
19.7 30.5
Chemical treatment
(commercial alum,
500 ppm):i:
% BOD removal
9.2
27.0
14.0
60.0
15.4
38.3
27.3
¶4 COD removal
9.6
23.0
23.0
78.0
13.9
45 ,4
32.2
¶4 color removalt
0
9.0
0
76.0
48.2
65 .2
33.0
Activated powdered
carbon treatment
(500 ppm)
¶4 BOD 5 removal
61.2
29.2
76.1
7 1.9
35.0
22.7
49.4
¶4 COD removal
72.7
18.7
69.0
59.6
32.0
52.0
50.6
‘4- color removalt
61.5
67.4
67.1
71.4
79.8
52.7
66.6
* Removal data for the biological study were based on the overall treatment results for the entire study period including removal
data both before and after 1000 ppm carbon addition to the reactor and represent removal of the listed parameters from the decanted
sample compared with the raw concentrate feed.
t Color data represent unfiltered or “apparent color.”
t Removal data for the alum treatment were based on the best overall treatment (500 ppm in all cases) and represent removal
of the listed parameters from the decanted sample after floe settling compared with the untreated raw concentrate.
§ Data for the carbon treatment were based on the best overall treatment (5000 ppm in all cases) and represent removal of the
listed parameters from a treated filtered sample compared with an untreated filtered raw concentrate sample.
(% removal)
C
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TABLE 3. REMOVAL EFFICIENCY OF VARIOUS
TREATMENT METHODS (% ) *
Constituent
Bh ogical
treatment
Alum
coagulation
Carbon
adsorption
Reverse
osmosis
BOD 5
70-95
50-70
60-95
80-98
COD
30-70
50-70
60-95
80-98
Solids:
Total
5-10
5
10-30
70-98
Volatile
10-50
50
50-80
75-98
Suspended
30-90
80-98
60-90
95-100
Color
10-80
80-90
80-98
95-100
Alkalinity
10-20
0-20
5
80-95
in
a particular
DECANTATE SAMPtE
FOR ANALYSIS
MIXED REACTOR
SAMPLE FOR
ANAL P 5 15
The general treatment efficiency of alum treatment is shown in
Tables 2 and 3. It can be seen that the total solids present in the
waste stream decrease very little in most cases. This is because of
the addition of soluble sulfate and neutralizing chemicals when the
alum is added to the waste stream. If the treated waste is to be
reused as plant process water, the sodium, chloride, or sulfate may
build up to an intolerable range rapidly. In this case, reverse os-
mosis or ion exchange will be required to remove electrolytes.
Carbon Adsorption
Activated carbon has been used to treat many industrial waste
streams for several years. It has the capacity to remove organic
chemicals and dyes from the wastewater. Some transition metals
may be adsorbed to a limited degree, 4 but more efficient processes
such as ion exchange, 5 may be used for their removal.
Carbon will adsorb organic chemicals with limited water solu-
bility from industrial waste streams.° Chemicals such as methanol,
* These results are ranges for several studies. The value
case may vary from this range.
pH ADJUSTMENT
WITH NITROGEN
AND PHOSPHORUS
NUTRIENTS ADDED
Figure 1. Schematic of a batch-fed biological reacter.
91
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acetic acid, ethylamine, and ethylene glycol are not adsorbed sig-
nificantly by carbon because of their high water solubility. Those
which have very low water solubility, such as dye pigments, are
not effectively adsorbed by carbon at room temperature. Chemicals
with very large molecular weights, such as organic polymers, are
not effectively adsorbed by carbon. That is to say, a small per-
centage of the chemical would be adsorbed from water after sev-
eral hours at room temperature. In this case, it would not constitute
a practical treatment method.
The only way the treatment of any waste stream can be assessed
is by conducting laboratory and pilot plant studies to get good
design data. The plant installing a new treatment system must be
prepared to look into the future and accurately estimate what
processes and chemicals will be used. If carbon adsorption is used
as a treatment method, it must be as suitable for the future waste
stream as it is for the present.
The average treatment efficiency for carbon adsorption is given
in Table 3. If salts are a large portion of the total solids, their
removal will be low. If the waste stream contains medium molec-
ular weight organics, dyes, and detergents, it can be treated very
effectively by carbon. The process must be carefully evaluated
before the waste treatment plant is designed.
Reverse Osmosis
Reverse osmosis systems are defined for this paper as membrane-
containing modules or units capable of rejecting low molecular
weight salts, such as sodium chloride, to an efficiency of 30 % to
98 %. These figures are arbitrary, but they at least separate the
membrane systems (ultrafilters) that are used to filter out colloids
and polymers of molecular weights of 10,000 or better. 7 The spec-
trum of molecular sizes that are removed overlaps in theory and
practice, so it is best to define the case for each study.
The other treatment methods (biological, coagulation, carbon
adsorption) can be used to recover water, but they are not conven-
tionally used to recover process chemicals from a waste stream.
That is, biological treatment degrades part of the waste chemicals
while contaminating the water containing them with a biological
colloid. Coagulation contaminates the chemicals it can remove
from the waste stream with an alum sludge, and carbon adsorption
destroys the chemicals it removes from the waste stream when
the carbon is reactivated at 1700 C.” (This is the common way
carbon is used to treat industrial waste.)
Reverse osmosis, on the other hand, can isolate a product water
of comparatively high quality and a concentrate water containing
80 % to 95 Ye of the chemicals present in the waste stream. 7 Data
taken from an actual pilot plant operation are presented in Tables
4 and 5. The chemicals recovered here have been used in actual
plant-scale dyeings.
92
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TABLE 4. ANALYSES OF PRODUCT WATER OBTAINED BY REVERSE OSMOSIS TREATMENT OF
TEXTILE DYE WASTE*
Cycle
Constituent (ppm) 1 2 3 4 5 6
number
9 10 12 14 Tap water
COD 25 20 20 15 15 25 30 200 10 25 <4
BOD 10 5 5 4 0.3 1 2.7 1.3 2 1 0.6
TOC 3 4 4 4 4 ..... ..... ...... 5 4
pH 6.1 6.0 6.4 6.5 7.1 7.2 6.2 6.2 6.4 5.9 6.7
Alkalinity 10 15 15 15 25 15 40 3 10 8 27
Hardness 30 15 20 5 5 10 4 6 3 0.5 19
Total solids 100 270 130 280 440 285 630 215 230 50 67
Volatile solids 30 nd 20 40 40 60 95 75 65 15 36
Dissolved solids 100 270 130 280 440 285 630 205 230 50 59
Color (Pt-Co) 30 20 13 6 30 60 30 60 20 40 13
Turbidity (FTIJ) 2.4 0.5 1.3 0.8 3.4 6.3 1.5 6 2.0 2.5 1.11
Metals:
Calcium 0.5 0.24 0.10 0.5 0.17 0.88 1.00 0.08 1.45
Zinc <0.04 0.08 0.7 0.06 0.82 0.50 0.04 0.07
Mangnesium <0.01 0.1 . 0.28 0.22 0.9 0.58 0.78 0.42 0.02 0.96
Chromium <0.1 <0.1 0.1 0.10 <0.1
Copper 0.4 0.8 0.04 <0.04
Iron 0.04 <0.13 <0.1 0.63 1.13 0.14 <0.68
Mercury (ppb) 0.3 nd 0.56 2.51
Magnesium <0.1 0.04 0.03 <0.05
Sodium 94 160 90 270 55 75 15 10
* La France pilot project sponsored by EPA.
-------
TABLE 5.
ANALYSES OF CONCENTRATED RESIDUES OBTAINED BY REVERSE OSMOSIS
TREATMENT OF TEXTILE DYE WASTE*
Cycle
Constituent (mg/I) 1 2 3 4 5 6
number
7 8 12 14 16
435 190 415 365
10 15 45 15
COD
425
815
455
580
690
BOD
70
135
60
102
95
TOC
87
200
110
165
220
pH
6.7
6.5
7.0
7.2
7.2
Alkalinity
110
135
110
160
190
a
Hardness
Total solids
90
2360
120
5570
80
2545
90
3020
135
4425
Volatile solids
200
450
280
310
405
Dissolved solids
2330
5540
2480
2985
4230
Color (Pt.-Co)
850
1250
1500
1000
1200
Turbidity (FTU)
39
31
2
40
30
Metals:
Calcium
3.0
6.5
9.0
Zinc
9.7
8.5
Magnesium
1.2
.....
. . ..
10 .5
13.8
Chromium
<0.1
<0.1
0.1
7.4
8.0
7.5
6.8
140
155
115
95
130
50
55
245
3425
1580
2510
4320
315
165
275
245
3435
1480
2450
4320
1250
1300
1680
920
80
8
15
4
6.0
1.0
8.1
34
9.0
2.4
3.1
7.2
17.0
4.5
9.6
27.0
430
20
230
6.7
160
190
3025
275
3025
1100
35
7.5
3.0
15.0
0.6
255
55
100
9.0
250
130
3110
3055
190
18
11.5
1.8
12.0
* La France pilot project sponsored by EPA.
-------
If the membrane is suitable for high-temperature operation, hot
water can also be recovered. A flow scheme for conventional bio-
logical treatment is presented in Figure 2. A flow scheme illustrat-
ing how reverse osmosis may be attached to an in-plant process is
shown in Figure 3. Here the wastewater from a specific process
unit is treated before it is contaminated with other chemicals from
other processes. The chemicals are recovered in their purest form
most suited for reuse. The water and energy (hot water) can also
be recovered for reuse. This system of direct reverse osmosis re-
covery at the in-plant point source can be applied to many plant
processes. The process must be understood, and modifications in
the process may be required before a reverse osmosis recovery sys-
PROCESS WATER
1 MGD
ENERGY
WATER
Figure 3. Recovery of water and chemicals at unit process.
WASTE WATER
DISCHARGE
1 MGD
I — — — DRAIN
HYPERFI LTER
BIOLOGICAL TREAflIENT
CLARI Fl ER
WASTE
SLUDGE
Figure 2. Plant using 1 mgd process water.
CHEMICALS
I CONCENTRATE
UNIT
PROCESS
PRODUCT
95
-------
tern is installed. The point is that if a chemical is recovered and
reused, its original cost may be less important than the function it
performs in the process. The stability of the chemical will (a) de-
termine how many times it may be reused in the plant process and
(b) indicate if degradation products with adverse effects on the
process would be formed from its repeated reuse.
When reverse osmosis is used on a composite waste stream out-
side the plant, it may be used for all of the plant waste or part of
the plant waste stream.
To get an idea of how this may compare with present technology,
a diagram is shown in Figure 2 that illustrates the conventional
biological waste treatment plant. All of the water coming into the
plant each day is consumed in the process and becomes part of the
manufactured product or ends up in the waste stream. The water
must be purchased or manufactured by the plant. The waste stream
must be treated before it is discharged. Present EPA regulations
indicate that no pollutants will be allowed after 1985) Since bio-
logical treatment only removes a fraction (30% to 70 4 ) of the
total organics in most industrial waste streams, it will have limited
use in meeting 1985 standards. Although biological treatment will
not be the complete answer to waste treatment in the next few
years, it will play a very important part.
Chemicals that may not be treated with high efficiency by re-
verse osmosis, carbon adsorption, or chemical coagulation may be
completely and effectively degraded by biological treatment. These
include solvents such as methanol, acetone, glycol, methylamine,
and formaldehyde. Other chemicals such as glucose or starch may
be too unstable to be recovered and reused in a plant process.
The plant would contain two outfall streams; one would contain
chemicals that would go directly to a biological treatment plant for
degradation, and another would go directly to a reverse osmosis
treatment plant. Figure 4 shows how a plant would decrease its
outfall from 1 to 0.1 mgd of sludge, which could be disposed of by
spray irrigation and thereby eliminate a wastewater outfall alto-
gether. This scheme will not constitute zero discharge in many
PROCESS WATER
WASTE SLUDGE 0 1 GD
Figure 4. Integrated design; plant recovering 9O% wastewater.
MAKE—UP _______
0,1 MGD
PRODUCT WATER O S MUD
TO UNIT PROCESS
98
-------
cases, as the sludge preparation for disposal may be significant,
and thus a limiting factor. Another factor will be the buildup of
dissolved solids in the process that recovers 90 % of its wastewater.
For example, if a plant uses process water of the general quality
shown in Table 6 and recovers wastewater containing 1000 ppm
dissolved solids, the plant adds a little over 900 ppm dissolved
solids to the water passing through the plant. If 90 % of the water
is recovered and recycled as shown in Figure 4, the buildup of
dissolved solids could be near 9000 ppm, a level that could make
the treated water unsuitable for plant reuse. In such a case, close
inspection of in-plant processes will need to be made to determine
where salts may be eliminated from the process.
TABLE 6. ANALYSES OF FRESH WATER USED BY
TEXTILE FINISHING PLANTS*
Constituent
Plant A
Plant B
Plant C
BOD 5
0
0
0
COD
5
2
6
Total solids
50
92
60
Dissolved solids
45
88
58
Suspended solids
2
4
2
Volatile solids
9
20
5
pH
7.5
7.6
7.8
Alkalinity
18
36
10
Hardness
3
8
12
Color
Phosphorus
0.1
Total nitrogen
0.6
Nitrate
0.3
.. -..-
Chloride
0.6
* All results reported in ppm except pH and color (Pt-Co units).
No doubt more worry would be involved for the plant manager,
but such a system is a valid consideration for the future. A process
chemical in the future will be chosen for its compatability with the
waste treatment scheme, as well as its importance to the process.
This appears to be the mechanism that will give society the desired
increases in goods and services and at the same time protect the
environment.
REFERENCES
1. Public Law 92-500, 92nd Congress, S. 2770, October 18, 1972.
2. Scaramelli, Alfred B. and DiGlano, F, A. “Physical and Chemical Methods
Review,” Journ. Water Poll. Control, Fed. 47, 1249 (1975).
3. SnIder, E. H. and Porter, J. J., “The Treatment of Waste Sludges and
Chemicals for Disposal or Incinerators,” Textile Wastewater Treatment
Seminar, Hilton Head, S. C. January (1976).
97
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4. Hassler, J. W., Activated Carbon, Chemical Publishing Co., Inc. New York
(1963).
5. Hirnsley, A. and MeArvey, F. X. “Role of Ion Exchange Processes in Pol-
lution Control,” Ion Exch. Membranes 1 3, 148 (1973).
6. Aled, D. It “Removal of Organic Material by Adsorption on Activated
Carbon,” Chem. & Ind. 17823 (1973).
7. Brandon, C. A. and Porter, J. J., “Complete Recycle of Composite Textile
Dyeing and Finishing Wastewater,” Environmental Symposium, Am.
Assoc. of Textile Chem. and Colorist, May (1975).
98
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REMOVAL OF REFRACTORY SUBSTANCES
FROM TEXTILE WASTEWATER
Jerzy Kurbiel and Thomas N. Sargent
ABSTRACT
The U.S. Environmental Protection Agency (EPA) and the Pol-
ish Institute for Economy and Water Management (IEWM) are
presently cooperating in an effort to investigate the effectiveness
of selected advanced wastewater treatment processes. Combined,
biologically treated, textile-municipal wastewaters are to be stud-
ied. The advanced processes include ion-exchange, carbon adsorp-
tion, chemical coagulation, oxidation, filtration, and reverse os-
mosis. The project plan calls for the investigation of the processes
to be carried out singly and in combination.
The general approach to the investigations was to begin on the
laboratory scale, then conclude on a pilot scale at the Andrychow
Treatment Facility. The laboratory-scale work was performed at
the IEWM facilities and the Krakow Polytechnic University in
Krakow, Poland. Typical removals by mixed media filtration are
55, 60% to 80%; BOD, 3% to 60%; COD, 30%; and detergents,
20%. The results of the application of other processes are also
given. (The data given are preliminary and subject to final yen-
f lcation and review at the termination of the project.) Reverse
osmosis is the only one of the processes in which the actual pilot
investigations have not begun. At present, the fabrication and in-
stallation of the reverse osmosis units are underway.
It is import ant to note the interrelationship of this PL-480-
sponsored project and the current and future U.S. research pro-
gram in textile wastewater treatment. No longer is it sufficient to
remove only BOD and suspended solids. The current interests in
industrial waste treatment are removal of refractory compounds
by these and other advanced waste treatment processes.
RESEARCH OBJECTIVES
The U.S. Environmental Protection Agency (EPA) and the Pol-
ish Instytut Mateorologii i Gospodarki Wodnej (Institute of Meteor-
ology and Water Management) (IMGW) are investigating the ef-
fectiveness of several advanced wastewater treatment processes
99
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on combined, biologically treated, textile-municipal wastewater.
The textile industry discharges a wastewater that varies widely in
physical and chemical characteristics, primarily because of the
batch nature of their processing operations. The wastewaters are
typically high in color and oxygen-demanding materials, are vari-
able in pH, and may contain refractory (or difficult to remove by
conventional treatment techniques) substances. These character-
istics, together with previous studies on biological treatment, sug-
gest that treatment by some processes other than, or in addition
to conventional biological treatment is necessary for satisfactory
treatment. In 1973, the EPA and the IMGW began the evaluation
of ion exchange, carbon adsorption, chemical coagulation, oxida-
tion, filtration, and reverse osmosis as tertiary treatment processes
following conventional primary and secondary treatment. The in-
vestigations are being done on laboratory and pilot scale at the
Krakow Division of IMGW, Krakow Polytechnic University, and
the municipal treatment plant in Andrychow, Poland. The treat-
ment investigations are scheduled to be completed in December
1976.
RESEARCH DESCRIPTION AND APPROACH
The Andrychow Cotton Textile Plant produces a variety of
textile fabrics from a blend of cotton and synthetic fibers (70 ‘7o
and 30 / , respectively). The whole yearly production amounted to
53 million m, or approximately 8.7 million kg.
The plant is divided into five departments: spinning, weaving,
fiber dyeing, finishing “A”, and finishing “B”. The total yearly vol-
ume of water used within the plant is 2.02 X 10” m’ (534 X iO gal).
The textile processing operations employ a wide variety of chem-
icals, including many types of dyes (reactive, vat, ice, indigosols,
sulfuric, disperse), detergents, and alkalis (caustic NaOH).
The Andrychow wastewater treatment plant (Figure 1) treats
wastewater containing municipal sewage and textile wastewaters.
ML IPdICIPAL -
SEWAGE
TEXTILE.
WA STE WATER
Figure 1. Andrychow treatment plant flow diagram.
r— PRIMARY
(FULL. SCALE)
(PILOT SCALE)
or- rann
(PILOT WAIl)
100
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The primary portion of the plant treats a daily combined flow of
14,000 ma. The secondary (activated sludge) pilot plant treats a
daily maximum of 600 m 3 . This secondary treatment provides the
influent to the tertiary portion of the system. The tertiary proc-
esses (Figure 2) include rapid sand filtration (single or multimedia
filters), granular carbon adsorption, chemical (alum) coagulation,
ion exchange, oxidation with chlorine and ozone, and reverse os-
mosis. These unit operations are investigated in various combina-
tions to evaluate the overall efficiencies. The scale of application
of these tertiary processes and a more complete description is
provided in the following text.
OZONE OR
CHLORINE
OXIDATION
Figure 2. Diagram of tertiary
plant.
physical/chemical processes at Andrychow pilot
At present, a volumetric proportion of municipal sewage and
textile wastewater during dry weather flow approximates 1: 1.
Municipal sewage is characterized by rather low B0L\ con-
centrations, ranging between 100 and 300 g/m 8 , with an average
of 170 g/mI 02.
Flow and concentration of textile wastewater undergoes con-
siderable fluctuations both during a day and a season. Concentra-
tion of pollution parameters in daily average samples are:
B0D 1 up to 660 g/m 3 02
Suspended solids 20 to 240 g/m
COD 100 to 700 g/m 02
Color up to 1600 g/m 3 Pt
Detergents 14 to 110 g/m 3
In spite of pH control within the textile plant, the pH after pre-
treatment at the textile plant varies from 6.8 to 10.1.
ION EXCHANGE
EFFLUENT
REVERSE
OSMOSIS
UNIT
OXIOATION &.
pH CONTROL I
PUN,
101
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The secondary effluent characteristics from the biological pilot
plant that treats the combined wastewater are as follows:
Average BOD
removal 87%, with effluent concentra-
tion about 20 g/m ft
COD 66’4 and 70 g/m 02
Detergents 70% and 5 g/m
pH varies between 7.0 and 8.5
Of the heavy metals, 40 Y are removed with effluent concentra-
tions less than 0.8 g/m. Average removal of color by biological
treatment was 50 . Some dyes were not removed at all. Color
concentration in the effluent was in the range of 20 to 160 g/m
(Pt units).
Tertiary treatment processes were investigated on the labora-
tory scale, followed in most cases by the second step study at the
pilot plant. Laboratory tests were essential for preliminary assess-
:nent of the technical feasibility, selecting the mode of operation
and range of technical parameters, or chemicals, involved. Because
of the laboratory data and experience, it was possible to operate
and manage the pilot investigations with optimized cost and time.
Rapid filtration on one or two media filters filled with sand and
anthracite was conducted on both laboratory and pilot scale, mainly
as a preliminary operation before another tertiary treatment proc-
ess, or as a supplement to coagulation. The 150-mm-diameter col-
umns were chosen for pilot scale after proof that this size had
negligible wall effect.
Coagulation was studied as an independent process and is also
being planned in combination with oxidation, carbon adsorption,
and ion exchange. Pilot research included a conventional unit with
flocculation and sedimentation compartments as well as a new
concept of contact coagulation on filter. Supplementary laboratory
jar tests to choose proper coagulants and their doses were per-
formed.
Carbon adsorption experiments were conducted in two stages:
first, laboratory tests to evaluate the adsorption properties of
different granular carbons (including US Calgon and Polish Z-4
brand), and second, pilot investigations in 150-mm plastic columns
to evaluate the effectiveness of organic refractory substances re-
moval under continuous flow conditions.
The ion exchange process was also tested in two stages. Labora-
tory investigation allowed the researchers to select the most effi-
cient ion exchange resins of both the cationic and anionic types
in relation to color removal. A larger scale study applying con-
tinuous flow principles was conducted at the pilot plant scale.
Testing of the oxidation process was carried out intensively, first
in the laboratory to prove technical feasibility of this process;
pilot tests are to be performed later. Such oxidants as chlorine
and atmospheric oxygen applied individually and with nickel and
102
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IJV light as catalysts were tested in batch laboratory experiments.
The application of ozone was also evaluated. For further pilot
plant research, chlorine and ozone were selected from the oxidants.
The Filtration Process
After the preliminary 1973 filtration investigations on a labora-
tory scale, the essential pilot scale research was started. Filtration
metaplex columns were used with a 150-mm diameter and a
height of 2.5 m.
The one-layer sand beds (granulation 0.5 to 1.5 mm , 1 m high)
have been tested as well as the dual media beds consisting of
anthracite (granulation 1.5 to 2.0 mm, 0.5 m high) and sand (gran-
ulation 0.75 to 1.5 mm, 0.5 m high). The hydraulic load in the
range of 4 to 15 m/m2/hr has been applied. Removal of contam-
inants in the following limits have been observed:
Suspended solids 60 ‘4 -80 %
BOD 30%-60’4
COD 30%
Detergents 20 ‘4
The relative efficiency is primarily dependent on the concentration
of suspended solids in the wastewater influent.
At the I-rn bed depth, no distinct influence of granulation or
hydraulic loads on the efficiency of contaminant removal is appar-
ent. For the shallower beds, a slight influence was noted.
The kind of bed, its granulation, and its hydraulic load have a
basic influence on the value of the occurring head losses, the
related length of the filtration cycle period, and the economic
factors.
Previous investigations indicate that when a high degree of
treatment is needed, filtration is worthy of recommendation as a
tertiary process to be carried out after conventional biological
treatment. Filtration is also applicable as a pretreatment for such
processes as adsorption, oxidation, ion exchange, and reverse
osmosis.
The Coagulation Process
In the coagulation process, contaminants are removed as a re-
sult of:
—removal of the colloids,
—generation of slightly soluble compounds (complex com-
pounds and salts), and
—sorption on the precipitated hydroxides.
Analysis of the applied dyes indicates that these dyes can be
partially precipitated from wastewaters at a decreased pH value
and an increased redox potential, and by coagulation.
The decreased pH value causes the increasing concentration of
metal ions of the coagulant, which supports the precipitation of
103
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slightly soluble salts and complex compounds. The laboratory in-
vestigations have been performed on the influence of the lower pH
value as well as on the increase of the redox potential on the
elimination of color-yielding substances from the biologically
treated wastewaters. The diminution of the extinction in the vis-
ible spectrum range is a measure of the treatment efficiency.
Aluminum sulfate dosages from 100 to 600 mg/I were tried.
The mean percent of color reduction for six different wastewater
samples at three pH values are shown in Figure 3. As can be seen
from the curves, a decrease in pH has a positive influence on
removal of color-yielding substances. The one-unit reduction of
pH causes an increase in the mean color removal of about 25 %.
The influence of the application of NaOCl on the reduction of
color-yielding substances is also shown.
In Figure 3, the coagulation of the wastewater samples is also
presented at the same pH values but with a dosage of 8 mg/l of
NaOC1. The positive effect of the oxidant combined with coagula-
tion on the reduction of color-yielding substances is shown. At
the higher pH value, the reduction increase amounted to 20 %.
Concentration of the compounds determined as non-ionic deter-
gents amounts to a few mg/l.
— — -— — — 8mg/I OF NaOCI ADDED
100 - _ _ _ _ — NO OXIDANT ADDED
90 -
80
70 pUS?
60 -pH 5.7
pH 6.5
50 -
40
pH 7.5
30 .pH8.5
20 -
10 -pH 7 ,5
0
100
200 300 400 500 600
A1 2 (50 4 h 48 H 2 0 — DOSE.
mg/I
Figure 3. Influence of coagulant dose, pH and chlorine preoxidatlen on color
removal in biologically treated wastewater.
0
C
>
0
LU
0
-J
0
0
—S
. 1 I
104
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In the Andrychow pilot plant, investigations were carried out
concerning the ttc;tIrnen : sihi1ities of the combined municipal-
textile wastewater after activated sludge treatment by coagula-
tion with AL, (SO 1 )
The coagulation process has been carried out at the same time
in two technological systems:
—with a simultaneous upward filtration through a sand bed,
and
—in a reaction chamber (with suspended flocs) followed by
filtration through an anthracite sand bed.
The 150-mm-diameter coagulation columns have contact with
the following layers of materials from the bottom up:
Gravel 0.4-4 mm, height 0.15 m
Sand 1.2-2 mm , height 1.50 m
Sand 0.4-8 mm, height 0.15 in
The suspended flocs reaction chamber has a diameter of 300 mm.
The height of the flocs layer amounts to 1.5 m.
The filtration column, working in combination with the reaction
chamber, was filled with two layers:
Anthracite 0.12-2 mm, height 0.5 m
Sand 0.4-0.8 mm, height 0.5 m
A dose of about 200 mg/I of AL (SO 1 ) 18 H 2 O was applied.
Contact coagulation was carried out at a rate of about 2.0
mVm2/hr. The whole filtration cycle lasted about 24 hr. Waste-
water pH was decreased by application of hydrochloric acid. The
average results from a 3-week period are listed in Table 1.
To compare the influence of increasing the redox potential be-
fore the process of contact coagulation, 10 mg/I NaOC1 was added.
In the same series, the pH value was decreased as well by adding
hydrochloric acid (Table 1).
Investigations of the suspended flocs system and coagulation
followed by conventional filtration have been performed.
The average rate of flow iii the reaction chamber amounted to
2.0 m1(m2/hr. The r:t; f filtration through the anthracite sand
bed amounted to about 6 in hr. The average results are given in
Table 1.
DISCUSSION
In the contact coagulation process, a positive influence of the de-
crease of wastewater pH on removal efficiency has been deter-’
mined, At a decrease in pH 7 to 5.7, the average color removal rate
increased 16 ‘/ and COD removal increased 20 ‘/e. When coagula-
tion was carried out in an identical system but preceded by oxi-
dation, color and CUD removal rates at the same pH increased
18 ¶A and 25 ¶Z , respectively. The influence of oxidation on the
amount of the COD and color removed by the application of
200 mg Al. (SO. ), l8H O was considerable.
105
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TABLE 1. EFFECTIVENESS OF PILOT PLANT COAGULATION PROCESS PERFORMED IN CONTACT
UPFLOW FILTERS AND CONVENTIONAL UNIT
Concentration of
constituents in
activated sludge
Activated
At pH
sludge effluent after pH
200mg l AL, (S
5.7 At pH
control an
04) 18 H.
6.4
d coagulation with
0
At pH 7.0
Concen-
Removal, Concen-
Removal,
Concen-
Removal,
Item effluent, pH 7.9
tration
tration
%
tration
%
Effect of contact
coagulation alone:
Suspended solids, mg/i 43 18 58 9 79 15 63
COD, mg/l 0 74 24 67 23 68 35 47
Color, mg /Pt 64 25 61 29 54 35 45
Effect of contact
coagulation combined
with previous NaOCI
oxidation, 10 mg/i:
Suspended solids, mg/l 39 11 72 16 59 12 69
COD ,mg 1O 0 90 19 79 31 65 41 54
Color, mg/i Pt 74 18 76 27 62 31 58
Effect of conventional
coagulation followed
by multimedia filtra-
tion—no pH control
or NaOC1 added:
Suspended solids, mg/i 39 9 77
COD, mg/I 02 30 36 60
Color, mg/i Pt 74 40 46
-------
Volumetric coagulation with filtration at the same pH values
achieved nearly identical removal rates. A 13 % higher COD re-
moval rate can be explained by the lower suspended solids content
in the effluent.
The Ion Exchange Process
Pilot plant investigations of the ion exchange process were
carried out in the fo Il owing system (Figure 2). Wastewaters of an
industrial: domestic volume ratio of 2: 1 after biological treatment
were directed through a sand filter to the cation exchanger (filled
with ZEROLIT 325/H +) and then through a CO degasifier to
the anion exchanger (filled with AMBERLITE 40/a—). The
resins evaluated in pilot scale were selected by laboratory investi-
gations. The column loads equal 6 bed volumes (BV) per hour.
One ion exchange cycle has been carried out up to the exhaus-
tion of the cation exchanger. The cation exchanger efficiency was
monitord by alkalinity analysis of the effluent and the anion ex-
changer efficiency by means of controlling the Cl ion content in
the effluent The cation exchanger regeneration was performed
with a HCI solution, whereas the regeneration of the anion ex-
changer, even though not entirely exhausted, was performed with
a NaCl solution. The load of the beds during the regeneration
amounted to 1.0 to 1.5 BV/hr.
Samples for the analytical process control were collected from:
—the wastewater effluent from the sand filter,
—the wastewater effluent from the cation exchanger filter, and
—the wastewater effluent from the anion exchanger filter.
The samples were taken every 4 hr, preparing one average sample
from the whole cycle. Analyses for the following constituents were
performed:
—alkalinity or acidity
—pH
—BOD
—COD (dichromate and permanganate)
—Cl
—color
—anionic and non-ionic detergents
The cycle time of the cation exchanger column, and simulta-
neously of the whole system, amounted to 24 hr (average). In the
system described above, five ion exchange cycles have been car-
ried out. Presently, the cation exchanger column has been dis-
connected, so wastewaters are passed directly to the anion ex-
changer column. Investigations were continued with increased
loadings (12 and 18 BV/hr).
Ozone Oxidation
Laboratory ozone oxidation investigations carried out using
batch tests have proved that removal of color differs for particular
107
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dyes added to biologically treated effluent. Removal rates ranged
between 11% and 87%.
COD concentration decreased 30% to 40%; the anionic deter-
gents were reduced 28 V to 75 ¶4 . TOC reductions during batch
ozone oxidation ranged from 16.7 V to 83.7 %, depending on the
kinds of dyes present in the solution.
Influence of contact time, type of dye solution, and concentra-
tion of dyes on effectiveness of oxidation has also been tested.
FUTURE PLANS
The main activity during the last year of the project (1976) is to
put into operation the reverse osmosis (hyperfiltration) unit, the
only process that has not yet been tested.
The pilot installation for reverse osmosis, which requires a sup-
ply of some sophisticated equipment (i.e., high pressure pumps
and membrane modules), has already been designed for applica-
tion of two process systems: conventional modules and dynami-
cally ormed membranes. Startup of complete installation is
planned for April 1976 in the Andrychow pilot plant on combined
municipal-textile wastewater after biological treatment. Further
plans include testing the hyperfiltration on overall textile waste-
water and finally on the separated wastewater from the dyeing
process. This last approach evaluates reuse of both product water
and concentrate.
The investigation performed in the last 3 years on laboratory
and pilot scale have enabled the tasting of various unit processes
in view of their technical feasibility and effectiveness in removing
refractory substances. Further investigations are planned at the
Andrychow pilot plant to include testing of the combination of
processes such as oxidation and coagulation, coagulation and ad-
sorption, ozonation and adsorption, coagulation and reverse os-
mosis. These investigations will prove the interaction of the proc-
esses responsible for refractory substances removal and optimiza-
tion of the treatment techniques.
108
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EPA RESEARCH AND DEVELOPMENT STUDIES
ON TEXTILE WASTEWATERS
Thomas N. Sargent
ABSTRACT
The U.S. Environmental Protection Agency (EPA) is active in
the development and demonstration of technology capable of meet-
ing the requirements and goals of the Federal Water Pollution
Control Act Amendments of 1972 (PL -92-5OO). The research and
development program includes domestic and foreign activities
dedicated to this principle. EPA has provided approximately $3.4
million in research and development funds since 1968. The general
scope of activities of the research and development program’s
industrial interface is presented.
The Environmental Protection Agency’s (EPA) research and
development program is now operating under the legislative man-
dates of the Federal Water Pollution Control Act Amendments
of 1972 (PL 92-500). These amendments have three principal dis-
charge restrictions for all industrial point sources. Briefly, these
are the implementation of “Best Practicable Control Technology
Currently Available” (BPCTCA) by 1977, of “Best Available
Treatment Economically Achievable” (BATEA) by 1983, and the
attainment of “Zero Discharge” as a national goal by 1985. The
effluent guidelines for the textile industry were published in the
Federal Register on July 5, 1974.
The purpose of my paper is to present the EPA research and
development activities for assisting industry to meet the require-
ments of the legislation. The basic research and development pro-
gram began in FY 1968. From FY 1968 through FY 1975, EPA has
funded 27 projects directed toward aiding the textile industry in
the development of treatment technology. The total value of these
projects is approximately $7.9 million, with EPA providing ap-
proximately $3.4 million, Included in the 27 projects were 9 grants
to colleges and universities, 3 grants to trade organizations, 14
grants directly to industry, and 1 grant to the Polish IMGW. The
scope of these grants has ranged from literature searches through
bench- and pilot-scale research to full-scale demonstrations at
109
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textile manufacturing facilities. The processes investigated on
bench pilot or full scale have been involved with demonstrations
ranging from basic biological treatment through advanced phys-
ical/chemical processes (hyperifitration, for example).
The objective in the early part of the research and development
program was either to develop and demonstrate new technology
or to apply existing technology in an area where it had not been
applied The current program—that is, since passage of PL 92-500
and the development of the effluent guidelines—-is directed toward
establishing technology applicable to the BATEA category of the
requirement, and especially to the techno’ogy areas where the “zero
discharge of pollutants” goal applies. The must important part of
this latter work is to develop and demonstrate water management/
treatment techniques that have as an integral feature the recycle
and/or reuse of the aqueous emissions and the materials in these
aqueous emissions.
Let me illustrate with a case history that exemplifies the stress
on reuse/recycle of the water and the “pollutants” in the water.
EPA awarded a grant to LaFrance Industries, a division of Riegel
Textile, in June 1972. The objective of this project was to demon-
strate the application of hyperfiltration technology in treating the
wastewaters from a textile dyeing and finishing plant. The investi-
gations included the use of both conventional (cellulose acetate)
and dynamically formed membranes. The resulting retentate and
permeate from the membrane units were evaluated for their re-
cycle and reuse potential in the dyeing processes. The membrane
units were operated on the pilot scale, and the reuse evaluation
of the retentate and permeate were done on a full-scale dye
machine. The final report for this project is now in preparation.
The preliminary evaluation of the system indicates that absolutely
no problems were encountered in using the permeate or the re-
tentate in the dyeing processes. A complementary effort to the
LaFrance project is currently underway in Krakow, Poland. This
effort is a part of the PL-480 program and is under the direction
of Dr. Jerzy Kurbiel.
This project is typical of those directed to solving EPA’s and
industry’s problem of cleaning up our Nation’s waterways. How-
ever, the Agency does not stop at the completion of a research
and demonstration project. In addition to the final report mecha-
nism, EPA goes several steps further in seeing that the information
gets to the user. Technology Transfer personnel, as a part of the
research and development program, function as an intermediary
between the researchers and the user community. The Technology
Transfer office uses capsule reports and seminars as their primary
communication vehicles.
The research and development program is also involved in other
activities of EPA. Research and development professional staff
have been actively involved in the effluent guidelines development
110
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efforts of EPA by serving as technical advisors to the EPA Effluent
Guidelines stall.
In summary, the research and development arm of EPA is vitally
interested in working hand in hand with our friends in domestic
industry and in other countries to develop effective pollution con-
trol, or water management techniques, for the private sector.
111
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TESTING OF BIODEGRADABILITY AND TOXICITY
OF ORGANIC COMPOUNDS IN INDUSTRIAL
WASTE WATERS
Jan i i. Dojlido
ABSTRACT
The development of industry in the world and the growing
production of new substances have resulted in the discharge of
many organic compounds into surface waters. Some of them are
biochemically resistant and may he harmful to humans using water
produced from contaminated surface waters. A knowledge of the
toxicity and biodegradability of the new organic compounds will
enable the proper treatment technoLogy to be applied.
The paper discusses various methods for determining the bio-
degradability of organic compounds. The long-term BOD test
method is a good one for determining oxygen uptake rates and
toxicity to microorganisms. Several classes of organics are dis-
cussed as to their effect on the biological treatment of wastewaters.
Preliminary results are given front. studies on compounds pres-
ent in wastewater from a plant producing artificial leather, “Pol-
corfam.” Methylethylketone was found to be easily degraded and
not toxic to microorganisms up to 800 mg/i.
INTRODUCTION
The development of industry in the world and the growing pro-
duction of new substances have resulted in the discharge of many
organic compounds into surface waters. Some of them are bio-
chemically resistant and harmful to aquatic life. They can also be
harmful to humans using tap water produced from the contam-
inated surface waters. These substances occur at very low con-
centrations undetectable by conventional analytical methods. For
these reasons it is necessary to know the nature of these sub-
stances, their behavior, and their harmfulness in the aquatic
environment. The methods for determining these substances are
indispensable. Knowledge of their properties enables the elabora-
tion of proper wastewater treatment technology, and in some
cases it can lead to the conclusion that some harmful substances
112
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cannot be discharged into the receiving waters. The purpose of
the research reported here is:
—to evaluate simple methods for biodegradability testing of
organic compounds
—to determine the biodegradability of several organic com-
pounds especially harmful to the environment
—to develop a fast toxicity test for organic compounds
—to determine the toxicity of several harmful organic sub-
stances and to establish permissible concentrations of these
substances in the aquatic environment
—to develop analytical procedures for the determination of
chosen organic substances.
METHODS FOR BIODEGRADABILITY TESTING
There are many varied methods for the determination of bio-
degradability of organic compounds:
a. Determination of BOD process by dilution. This method is
rather rarely used because it is labor-consuming and be-
cause results are of little use.
b. Manometric method of Sierp. The oxygen uptake of the
wastewater is determined by the change of the volume of
the air in a flask containing the wastewater sample.
c. Warburg’s manometric method of the wastewater sample
closed in a flask. Oxygen uptake is determined by mano-
metric measurement of pressure changes of the air above
the sample.
d. Static test described by R. L. Bunch.’ The organic compound
to be tested with addition of yeast extract and inoculum is
incubated in an open flask under standard conditions. After
a given time, a decrease in the concentration of the test
substance is analytically determined.
e. Electrometric method. The sample to be tested is continu-
ously stirred in a closed flask. Oxygen uptake is measured
by means of an oxygen probe immersed in the sample. One
of the apparatuses based on this principle is called ATA
(aerobic treatability apparatus) 2 An example of the results
obtained by means of this apparatus is presented in
Figure 1.
f. Another method of BOD determination is by means of the
apparatus known as the “Sapromat ” type. Over the waste-
water sample in a closed flask there is a constant concen-
tration of oxygen produced by an electrolytic generator at
the same rate as oxygen is used for the biochemical degra-
dation of organics. The oxygen uptake, determined from
the work time of the oxygen generator, is recorded every
hour. A typical example of the inhibiting effect of the test
substance on the BOD is presented in Figure 2.
113
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C
E
z
LU
C D
n
0
0
L U
C
C
a,
a,
a
C
a,
a
t
I-
L U
I —
C
z
C
C
U ,
L U
CONCENTRATlON mg/I
Figure 1. Typical curves showing stage of biodegradability of substances.
g. The laboratory-scale activated sludge model can be used
for biodegradability testing. Descriptions of many such
apparatuses can be found in the bibliography. One of them
is described later in this paper. A schematic diagram is
shown in Figure 3.
h. Simulated natural river conditions can be used for biode-
gradability tests. The simplest procedure uses an aquarium
with the river water stirred at a rate similar to the turbu-
lence in the river. The substance to be tested is added and
analyzed at definite intervals. Also, constant flow-through
types of apparatus are applied because they simulate the
natural conditions much better.
1 ’
0
TIME, hours
500
114
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theoretical
standard wastewater
a,
E
0
Figure 2. An example of the inhibiting influence of substances on BOO deter.
mined in Sapromat. If the observed curve (w + s) BOD is below the one
for (w) SOD, the added substance is toxic. The area contained between
the curves is the measure of the toxicity.
- =
SETTLING TANK
1.7 1
F?
WASTE _______
DISCHARGE
Figure 3. LaboratorY-scale activated sludge system.
(L. 1
PUMU 1
— 100 I/day)
RAW
WASTES
I L
ACTI VATED
SLUDGE
CHAMBER
8 liters
AIR
TIME, hr
115
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Analytical Procedures
In investigations on the biodegradability of organic compounds
by the methods described above, some of the analytical methods
used are BOD, COD, and TOC. However, analytical determination
of the changes in test substance concentration during the bio-
chemical process is the most advantageous. Usually in the biode-
gradability tests, pH value and the nitrogen forms content are
measured. In the case of activated sludge testing, the sludge char-
acteristics are also of great interest.
ORGANIC COMPOUNDS AFFECTING BIOLOGICAL
TREATMENT OF WASTEWATERS
Hydrocarbons
These compounds are slightly soluble in water, so removing
them from the water is rather easy. However, the tendency to
form an emulsion of hydrocarbons and water can be troublesome.
The hydrocarbons are slowly biodegradable. Biodegradability of
these compounds is known to decrease with an increase in molec-
ular weight and when the chain is longer and more branched.
The toxic effect of the aliphatic as well as the aromatic hydro-
carbons on the microorganisms of the activated sludge is observed
at high concentrations (above 500 mg/i). Though hydrocarbons
do not usually exhibit acute toxic effects, they can cause operating
difficulties in biological treatment plants.
Alcohols
Most alcohols are easily biodegradable. Biodegradability de-
creases as chain length increases. Alcohol concentration in the
inflow into the treatment plant is probably lower than 500 mg/l.
However, there are some alcohols of complicated structure that
are hardly biodegradable—for example, polyethylene glycols and
pen taery thritol.
Aldehydes and ICetones
The aldehydes undergo rapid biochemical decomposition if their
concentration in the wastewater does not exceed 300 mg/I. the
ketones are much more resistant to biodegradation. In the higher
concentrations, the aldehydes and ketones have a toxic effect.
Carboxylic Acids and Their Salts
Carboxylic acids and their salts submit relatively easily to bio-
chemical decomposition, and they do not disturb operation of the
activated sludge treatment plants.
Phenols
Many phenols are easily biodegradable. In Poland, several bio-
logical treatment plants effectively remove phenols from waste-
water in concentrations of 1,000 to 2,000 mg/l. However, hydro-
116
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quinone, which is toxic in concentrations above 500 mg ‘1, is some-
what resistant to biodegradation.
Halogen Derivatives
There is no accord among the results of biodegradability investi-
gations on halogen derivatives made by different authors. Most of
them have found these compounds resistant to biochemical decom-
position. Biodegradability of aliphatic chlorinated hydrocarbons
has been reported to increase when the chains are longer. The
MCPB (metachiorophenoxy butyric acid) and 2,4-D (2,4-dich loro-
phenoxyacetic acid) are very resistant and have a negative effect
on the wastewater treatment operation.
Generally, introducing halogen atoms to an organic molecule
significantly decreases the biodegradability of a given compound. t
Such easily biodegradable substances as phenols and aniline or
organic acids become difficult to hiodegrade after introducing a
chlorine atom to the molecule, and they are nearly nonbiodegrad-
able after introducing two or more chlorine atoms to the molecule.
In addition, most chlorinated hydrocarbons are slightly soluble
in water, and they easily form an emulsion in water.
A mines
The amines, aliphatic as well as aromatic, are biodegradable.
Many authors consider the amine group as decreasing biodegrad-
ability of the molecule; for example, aniline is easily biodegrad-
able, but the aminophenols and aminoaniline are slow to bio-
degrade.
Nitrites
Nitriles are easily biodegradable. The biodegradation of these
compounds consists of hydrolysis to appropriate acids.
Nitrocom pounds
The introduction of nitro groups to such aromatic compounds
as phenols, amines, aldehydes, and acids decreases their biode-
gradability. The nitrocompounds have toxic effects on the micro-
organisms active in the process of biological wastewater treatment.
Recently, a method of biochemical decomposition of nitrocom-
pounds by the separate culture of Azotohacter has been discovered.
Sulphur-Containing Compounds
Among the compounds of this group, the detergents occur most
frequently. Most of the investigators in the field of biodegradabil-
ity have just dealt with the problem of detergent biodegradability.
The alkylosulphates are the most easily biodegradable. Also, the
alkylosulphonates, suiphonated amides, and alkyl esters are easily
biodegradable. In case of ABS (alkylhenzenesulphonates), the rate
of biochemical decomposition depends on the structure of the alkyl
117
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chain. If this chain is branched, the biodegradation becomes difil-
cult and slow.
Other Organic Compounds
In addition to the above-mentioned organic compounds, many
others can be found in industrial wastewaters—f or example, car-
bohydrates, proteins, polymers, dyes, antibiotics, nonionic deter-
gents, etc. Only a few of these compounds were investigated from
the point of view of properties affecting biodegradability. Gener-
ally, it can be considered that the biodegradability of these com-
pounds depends on the kind of functional groups present in the
molecule, molecular weight, chain length, and chain branching.
Still, information is lacking about the biodegradability and toxicity
of many organic compounds. Those most frequently occurring in
wastewaters from Polish industry are listed below:
a. Hydrocarbons—Crude oil, mineral oil, kerosene, gasoline,
benzene, toluene, xylenes.
b. Alcohols—Methanol, ethanol, butanol, octanol, ethylene
glycol, glycerol, cyclohexanol.
c. Aldehydes and ketones—Formaldehyde, acetaldehyde, acre-
lein, acetone, methylethylketone, cyclohexànone.
d. Carboxylic acids and their esters—Formic acid, acetic acid,
propionic acid, palmitic acid, stearic acid, benzoic acid,
salicylic acid, phthalic acid, terephthalic acid, acrylic acid,
oxalic acid, methyl acetate, ethyl acetate, butyl phthalate,
dimethyl terephthalate, methyl methacrylate.
e. Phenols—Phenol, cresols, xylenols, hydroquinone, pyrocat-
echol, alpha naphthol, beta naphthol.
1. Halogen derivatives—Chloroform, carbon tetrachloride,
ethylene dichioride, trichloroethylene, tetrachioroethane,
ethylene chlorohydrin, epichiorohydrin, chioroacetic acid,
chlorobenzene.
g. Nitrogen-containing organic compounds—Dimethylamine,
diethanoloamine, aniline, toluidine, triethanoloamine, ethyl-
aniline, hexamethylenetetramine, diethylaniline, caprolac-
tarn, morpholine, thmethylforniamide, cycloexylamine, ace-
tonitrile, acrylonitrile, nitrobenzene, dinitrobenzene, dini-
trotoluene, trinitrotoluene, pyridine, melamine, dinitrochlor-
obenzene, nitrophenols, dinitrophenols, picric acid.
h. Sulphur-containing organic compounds—Thiourea, mercap-
tobenzothiazole, benzenesulphonic acid, carbon disulphide,
alkylbenzenesulphonates.
i. Other organic compounds—Nitrilotriacetic acid, methyl-
cellulose, dioxane, diethylene glycol, triethylene glycol, t n-
oxane, nonionic surfactants.
118
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MATERIALS AND METHODS
In the project being conducted by the Institute of Meteorology
and Water Management for the U.S. Environmental Protection
Agency, the organic compounds considered most harmful for the
Water environment are tested. The most harmful compounds are
Considered to be those that are toxic, difficult to biodegrade, and
present in industrial wastewaters at high concentration.
Materials
For the first part of the work, compounds present in wastewater
from plants producing the artificial leather Polcorfam were chosen,
The production of Polcorfam has started recently in Poland on the
basis of a license bought from the DuPont Company. In the waste-
Water discharged from this production, the following substances
are present and cause difficulties in treatment plant operation:
—.-methylethylketone (MEK)
—dimethylamine (DMA)
‘---dimethylformamide (DMF)
Methylethylketone MEK (butanone-2), formula CH 4 COC,H 5 ,
IS soluble in water. This liquid, similar to acetone, is applied in
many branches of industry, mostly as a solvent. In the production
of Polcorfam, the recovery of MEK from wastewater by means
of azeotropic distillation is applied, but recovery is not complete.
So in wastewater discharged from Polcorf am installations, MEK
Is present at concentrations usually exceeding 100 mg/l.
Dimethylamine_. DMA, formula (CHi) 2 NH, is a gas that con-
denses at 7 C (760 mm Hg) and is soluble in water. DMA is the
homologue of ammonia, and it has similar chemical properties.
Like ammonia, it forms complexes with Ag and Cu. In the weak
acidic milieu, DMA reacts with nitrites to form nitrosodimethyl-
amine, a suspected carcinogen.
Dimethylformamide__. DMF, formula (CHi) 2 NCHO, is a liquid
(boiling point about 150 C) soluble in water at every ratio. It Is
used in many branches of industry, mostly as a solvent. Under
Suitable conditions it easily hydrolyzes, forming formic acid and
DMA. After the preliminary treatment, wastewater from Polcor-
fam production contains about 150 mg/I DMP.
Other substances to be tested will be chosen from the list given
above.
Experj j j Procedures
Long-term BOD Determination by Means of Sapromat .Appara-
tus- - The test sample, containing an inoculated solution of standard
flutrient (yeast extract) and the added test substance, is kept in
the flask of the Sapromat apparatus, fully saturated with oxygen
and intensively stirred. Oxygen uptake is recorded every hour.
One experiment consisted of BOD determination for the blank
119
-------
sample (yeast extract solution) and also for several samples con-
taining increasing quantities of the test substance. The tests were
continued for 20 days, and the solution reached its near-ultimate
DOD.
Test Substance Decomposition Rate Determination by Means
of Sapromat— The tests were conducted as described in the pre-
ceding section, the difference being that a portion of the same
sample with a given concentration of test substance was intro-
duced to all flasks in the apparatus. At regular intervals, a flask
was removed from the apparatus and its contents analyzed for the
test substance concentration.
Determination of Decomposition Rate of Test Substance in River
Water— Water from the river receiving the wastes was tested in
aquariums holding 20 liters each. To this continuously stirred
water, a given amount of the test substance was added. The pur-
pose of such a test was to simulate natural conditions. The de-
crease observed in the given substance concentration should be
similar to that taking place in the receiving wastewater. The use-
fulness of such a test is limited if the test substance is volatile.
Determination of Effectiveness of Test Substance Removal by
Means of Model Activated Sludge Test— A laboratory-scale acti-
vated sludge model can be used for simulation of the process
occurring in the treatment plant. No fewer than two units in
parallel must be kept in operation. The first is fed with standard
wastewater, and the second one is fed with the same solution with
the added substance. The effectiveness of the activated sludge
process and the influence of the test substance on this process is
determined by means of chemical analysis of influent and effluent
concentration of the test substance, COD, NO 2 , NO 3 , volume index
of activated sludge, and microscopic analysis of activated sludge.
Simple Static Test of Decomposition Rate of Test Substance in
Standard Solution— The test substance in known quantities is in-
troduced to the set of flasks inoculated with the standard nutrient
solution. At regular intervals, the contents of a flask was analyzed
for test substance concentration, COD, and nitrogen forms.
Toxicity Investigations
Toxicity of organic compounds to be tested was determined by
means of acute toxicity tests. Static as well as dynamic (constant
flow) methods were applied. The following organisms for the tests
were chosen:
—Daphnia magna
—Asellus aquaticus
—Lurabriculus variegatus
—Lebistes reticulatus
Static Tests of Toxicity— These consisted of observation of be-
havior and reaction of test organisms over a 96-hr period. The
120
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test substance was added to 250 ml of water in open beakers. In
tests of this kind, the chemical composition of the beakers’ content
changed because of biodegradation of the test substance and the
accumulation of diverse products of metabolism.
Dynamic Tests— Dynamic tests were performed by means of a
proportional diluter. This apparatus is the automatic device for
continuous dilution of the test substance at the required ratio and
for feeding the containers in which the test organisms were
placed. In this system, the test substance remains at the same
concentration even during long-term tests, and the products of
metabolism are removed continuously. Because the proportional
diluter described 7 is equipped with open containers for test organ-
isms, it is not suitable for experiments with highly volatile sub-
stances. A volatile study apparatus is described in the following
section.
Apparatus for Testing the Toxicity of Volatile Substances— Some
toxic substances are very volatile and may be a threat to the health
of laboratory workers. Test results may also be affected by loss of
volatile materials during the experiment. Thus a special apparatus
Was constructed to test the toxicity of volatile substances (Figure
4). Temperature is thermostatically controlled. Through the bottle
containing the test organisms, a peristaltic pump forces a constant
flow of 50 to 100 ml/min of oxygen-saturated fresh water contain-
ing the test substance. The concentration of the test substance is
controlled by adjusting the pump. During the experiment, the test
solution does not contact the atmosphere; and at the same time,
the flow through the bottle renews the solution several times every
hour, thus removing the products of metabolism. Observations of
the test organism mortality are used to determine the LC 50 by the
graphic method or by computation, using the probits transforma-
tion.
Analytical Procedures
Sensitive analytical methods are required to determine the test
substance concentrations occurring in raw wastewaters, in the
effluents from wastewater treatment plants, in surface waters, and
at the concentration legally permissible in natural waters. Gas-
chromatographic methods are often the best among the available
procedures.
Determination of MEK
The gas chromatograph Pye-Unicam Model 1104 haS been ap-
plied in our laboratory. The column is filled with Poropak Q
covered with polyethylene glycol 1000 as a stationary phase. A
flame-ionization detector is used, and the carrier gas is nitrogen.
The direct injection of aqueous sample has been used, depending
on the concentration range, or sample concentration can be
121
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TEMPERATURE
REGU LATOR
DEVICE
achieved by extraction of MEK by means of toluene using sodium
sulphate as the salting-out agent. The lower detection limit is 0.1
mg/l.
RESULTS
Biodegradability Test Results for MEIC
Long-term (17-day) BOD’s— Long-term (17-day) SOD’s were
run in the Sapromat apparatus for six samples of MEK. The con-
centrations varied from 0 ot 800 mg/i. In addition to MEK, each
sample contained 200 mg/i yeast extract in dilution water and
150 mi/i domestic wastewater, both of which were previously
tested for their nontoxic and good inoculation properties. The BOD
time curves were drawn on the basis of oxygen uptake printed
.a. AIR
TANK
COLUMN
DILUTING WATER
INLET
FROM
VESSEL
INLET OF TOXICANT
Figure 4. Constant-flow apparatus for bioassay on volatile substances.
122
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records. Three of these curves are shown in Figures 5, 6, and 7.
These graphs show that after initial lack of oxygen uptake (lag
phase), the BOD curve is concave up to the inflection point, and
further on it is similar to the monomolecular reaction curve. In
the final part of the curve, two waves (probably caused by 1st
and 2nd stage nitrification) are visible (Figure 6). It can be as-
sumed that after the lag phase, the biochemical process, and
thereby the oxygen uptake, is under the influence of exponentiai
growth of bacteria. So the oxygen uptake rate should follow the
equation:
log = c + b • t
where
y = oxygen uptake, mg/i day
t = time, days, and
b growth coemcient, dar 1 .
400
C
o
2
300—
I
C
2
200-
2
0
S
U
100— 1
__________ L __ . I ‘ • __ 1
0123455789101112131415
TIME , days
Figure 5. SOD curve for sample containing yeast extract and : mg/I MEI(
123
-------
I 2nd stage nitritication
E
r
TIME. days
Figure 6. BOO curve for sample containing yeast extract (200 mg/I).
C ,
E
TIME, days
Figure 7. BOO curve for sample containing yeast extract and 400 mg/I MEK.
From the graphs made in coordinate system log dy/dt versus
time, one can read out (see Figures 8, 9, and 10):
—time of lag phase duration, — t 0
—time of exponential phase ending, — t 1
—growth coefficient b (from the slope of the straight line)
1st stage nitrilication
0
z
900
300
ii
0
1
2
3
4
5
B
7
8
9 10 11
12 13 14 15 16 17
124
-------
2.3 —
—
2.1 —
1.9 —
t .
1.7-
1.5 —
t 0 1
TiME, days
Figure 8. Oxygen uptake (control);
yeast extract
1.3 —
1 1
2.3
2.1—
1.9 —
4-
- .v
1.5
1.3 —
11__
S
ii
Figure 9. Oxygen uptaKe; yeast extract
+ 100 mgMEK/t.
0 t 0 1 t 1 2
TIME, days
2.5
S
23— 5
S
2.1
-a i.&
S
•5
1.7— 5
I.
1.5_ I
13 _______________ ____ I
— I II
TIME. days
FIgure to. Oxygen uptake; yeast extract
II
3 4
+ 400 mg MEK/I.
S IS
2
S
I — — — — —
3
125
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The oxygen uptake results are shown in Table 1.
TABLE 1. OXYGEN UPTAKE RESULTS WITH MEK
Time
MEK concentration,
mg/i
0
100
200
400
800
t 0 ,
hours
14
— 14
14
14
14
t 1 ,
hours
20
44
47
49
43
b,
dar’
n.d.* 0.38
0.46
0.40
0.46
* Not determined.
It has been assumed that in the next section, the BOD curve
follows the monomolecular reaction equation
y L/l—10 , /,
where
L = final BOD, mg/i 02
k 1 = coefficient, dar t , and
y and t = as above.
The parameters L and k 1 can be calculated by means of the least
squares method. The time of duration of carbonaceous process
(monomolecular) —the period of time between the end of the
exponential phase and the beginning of the first wave of nitrifica-
tion—has been considered. After computation of I c 1 and L for this
section of time only, the oxygen demand for nitrification (NOD)
in the first and second stage has been read out. A comparison of
the first- and second-stage NOD readout from the graphs, with
theoretical values calculated from the known ammonia and or-
ganic nitrogen content in the sample, has proved a mutual accord.
At the higher MEK concentrations, the NOD could not be read
out because of the small ratio of NOD to carbonaceous BOD. Re-
suits are presented in Table 2.
TABLE 2. BOD PARAMETERS FOR MEK -
MEK concentration, L NOD, t$
mg/i mg/l 02 mg/i 02 day -‘ days
0 95 82 0.47 3.5
50 194 90 0.49 4 .5
100 300 100 0.51 4.5
200 495 112 0.37 5.5
400 949 n.d.t 0.17 15
800 1995 n.d . 0.09 n.d.
* L denotes the fina’ carbonaceous BOD.
t is the time of the beginning of nitrification.
t Not determined.
§ NOD included.
126
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From the L 0 values, the total BOD of 1 g MEK was calculated by
subtraction of the blank sample BOD from the DOD of samples
containing MEK. The mean value obtained is equal to 2.1 g 02,
whereas the stoichiometric value amounts to 2.44 g 02.
Examination of MEK Degradation in the Sapromat Apparatus —
Six identical samples, each containing 200 mg/l yeast extract and
200 mg/l MEK, and inoculated with 150 ml/i domestic wastewater
for the first experiment were incubated in the Sapromat and the
DOD recorded. At regular intervals, usually 12 hours, a flask was
removed and the MEK concentration was determined. The second
experiment was performed, with the only difference being that
the content of the last flask from the first experiment was used for
inoculation instead of wastewater. The concentrations of MEK
were marked on the graph versus the time (Figure 11). From the
graphs, the long time of adaptation of microorganisms in the first
experiment is visible, whereas the graph for the second experiment
shows that adaptation time is significantly shorter. The MEK con-
tent in the first experiment does not show a significant decrease
during the first 2 days, and SOD during this period is equal to the
BOD of the yeast extract. In the second experiment, MEK degrada-
tion starts earlier, and the time required to achieve full MEK deg-
radation is 2.5 days compared with 5 days for the first experiment.
The Static Tests— The tests were performed in hydraulically
sealed bottles to avoid losses of MEK by evaporation. Over the
surface of the sample a volume of air was left to permit reaeration
of the sample. At regular intervals, the contents of a flask were
analyzed for MEK and COD. Initially samples contained 50 mg/I
yeast extract and 20 mg/I MEK. The samples in the first experi-
ment were inoculated with domestic wastewater, whereas sam-
ples in the second experiment were inoculated with the last
sample of the first experiment. Concentrations of MEK were
marked on the graph versus the time (Figure 12). Microorganisms
in the last sample of the first experiment were shown to be
adapted to the MEK milieu, since in the second experiment, MEK
degradation proceeded faster.
Examination of MEK Decrease in River Water— Tests were
made in aquariums containing 20 liters of Vistula River water.
In one aquarium, 20 mg/i MEK was used. The MEK decrease was
drawn on the graph versus the time (Figure 13). The graph shows
that after an adaptation period, the rapid degradation of MEK
results in almost full decay in 2 ,5 days. Repeated addition of MEK
to the same water has proved that river microorganisms were
adapted during the first 2.5 days. To estimate MEK decrease re-
sulting from evaporation, the control aquarium was filled with
Vistula River water to which was added 20 mg/i MEK and biocide
(50 mg/I HgClj. Analysis of the contents of this aquarium have
proved that only a part of the MEK decrease was caused by
evaporation.
127
-------
Figure 11. The test of MEK biodegradabilitY in Sapromat apparatus.
E
Q
I
co
140
0 tO
E
TiME. days
40
40
20
30 40
-------
I
g
I
S
I
Figure 13. Decrease of MEK content in river water.
TIME. days
Figure 12. Decrease of MEK content during
the static test of biodegradability.
2 3
TIME. days
129
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Toxicity Tests
MEK toxicity tests were performed as acute toxicity tests using
the fish Lebistes reticulatus as the test organism (Table 3). Results
show that fish tolerate relatively high MEK concentrations. First
results showed that the LC 50 for MEK after 24 hr equals 6 g/l.
During the 96 hr of the experiment, the toxic effect has decreased,
which can be explained by the degradation and evaporation of
MEK from the test solutions kept in open beakers. Thus a special-
ized apparatus for determination of volatile substance toxicity
was constructed for subsequent experiments (Figure 4).
TABLE 3. SURVIVAL OF Lebistes Reticulatus IN MEK
SOLUTION (STATIC TEST)
MEK concen-
Number of survivors
15
30
1
24
48
56
72
96
tration, g/l
mm
mm
hr
hr
hr
hr
hr
hr
Control
20
20
20
20
20
20
20
20
1.9
20
20
20
20
19
19
19
18
2.2
20
20
20
19
17
17
17
17
3.4
20
20
20
18
18
18
18
14
4.5
20
20
20
15
15
15
15
14
6.0
20
20
20
12
12
12
12
12
7.0
20
20
3
3
3
3
3
3
10.8
20
0
0
0
0
0
0
0
CONCLUSIONS
1. There is a lack of uniform, commonly used, simple, standard
methods for determining biodegradability of organic compounds.
2. Available information about biodegradability of organic com-
pounds is often divergent and difficult to generalize and apply in
practice.
3. There is a lack of information about the occurrence of many
organic compounds in surface water and about the harmful effects
on biocenosis exerted by these compounds.
4. The method of biodegradability testing by means of long-
term BOD curve examination has proved a good method for pre-
liminary investigation, yielding such information as units of oxy-
gen uptake, oxygen uptake rate coefficient, and toxicity to micro-
organisms. The method for measuring decay of the test substance
gives additional information about the relationship between BOD
and decrease in test substance concentration. The static test is a
good method that can substitute for the former test in case of
lack of Sapromat apparatus.
5. MEK is easily biodegradable and has no harmful effects on
the sewage microorganisms at concentrations up to 800 mg/l. The
130
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oxygen uptake rate coemcient k 1 amounts to about 0.5 dar 1 , if
the nutrients are in sufficient quantities. The rate of MEK bio-
degradability increases rapidly after the adaptation of micro-
organisms.
REFERENCES
1. Bunch, R. L., and Chambers, C. W., “A Biodegradability Test for Organic
Compounds,” Jour. Water Poll. Control Fed., 39(2), 181-187, 1967.
2. Genetelli, E. J., Nemerow, N. L., and Barbaro, R. D., “Instrument for
Determining the Treatability of Industrial Waste,” Proc. of the 26th In-
dustrial Waste Conference, Purdue University, p. 299-307, May 4-6, 1971.
3. Jayme, G., and Pohi, E., “Verglelch Neuer und Alter Methodes Zur
Bestimmung des Biochemisehen Sauerstoffbedarfs,” (“Comparison of New
and Old Methods for Determination of Biochemical Oxygen Demands”),
Wochenb latt fur Papierfabrikation, 23/24, 1967.
4. Stasiak, M., “Nowa Technika W. Inzynierli Sanitarnej,” (“New Tech-
niques in Sanitary Engineering”), Wodociagi I. Kanalizacja, Warszawa,
Poland, Arkady, Nr. 5, p. 247, 1975.
5. Biczysko, J., “Problemy Oczysczania Sciekow Przemyslowych,” (“Indus-
trial Waste Waters Treatment”), Krakow, Poland, 1972.
6. Schobel, A., and Tschen, M., “Toxikologische prusung und biochemisches
ABBAUVERHALTEN von abwassern achs der herbizidproduktlon,” Wasser
Wirtschaft-Tecbnik, 22, 342, 1972.
7. “Investigation of the Toxicological Aspects of Petrochemical Wastes Dis-
charged into Free Flowing Waters,” IMWM, Warsaw, Poland, USEPA
Research Grant, NO. PR-05-532-9.
131
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CONCEPTS, CRITERIA, AND MEASUREMENTS
OF BIODEGRADABILITY
Robert L. Bunch
ABSTRACT
Biodegradability has become a key word in the lexicon of ever y-
one interested in the pollution problem. Why, suddenly, is there
such interest in biodegradability? Traditionally, nature provided
the ultimate disposal of manmade wastes, but as man advanced
technologically, nature’s work became more difficult. In fact, nature
fails to degrade some of the newer manmade substances. Thus, the
accumulation in the environment of many of the newer products
synthesized by man and the advent of new legislation requiring
pretreatment for wastes that are not removed by conventional
wastewater treatment plants, has focused considerable interest on
biological degradation or biodegradability. Some researchers prefer
not to use the term “biodegradability” in connection with waste-
water treatment processes; they favor instead the term “treat-
ability.”
Biodegradability has been defined in several ways. In the real
world of wastewater treatment, the extent of biodegradation
within a fixed time limit is a very important consideration. In
principle, laboratory testing should show the true biodegradability
of the test material as it would occur in the environment or in the
wastewater treatment plants.
How biodegradable should a compound be? The possibilities
range all the way from slight to ultimate breakdown of the com-
pound to cell matter, carbon dioxide, and water. Biodegradability
must be measured in terms of its effect on the environment. The
future would indicate that the environmentally acceptable biode-
gradability criterion for products that become waterborne wastes
should be that they are completely degraded to products that are
harmless in surface and drinking waters.
This paper discusses in detail the definition and the various test
methods for determining biodegradability. The important features,
advantages, disadvantages, and limitations of each test method
are presented.
132
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GENERAL CONCEPTS
Biodegradability has now become a key word in the lexicon of
those interested in the pollution problem. To many it means
halting the spiraling mounds of garbage or developing a plastic
bottle that will disintegrate. Why, suddenly, is everyone getting
interested in biodegradability? Traditionally, nature provided the
ultimate disposal of manmade waste, but as man advanced tech-
nologically, nature’s work became more difficult. In fact, for some
of the newer manmade substances, nature fails entirely to degrade
them. Three examples that readily come to mind are plastic pack-
aging materials, some of the detergents, and pesticides. Thus, the
accumulation in the environment of many of the newer products
synthesized by man has caused considerable interest to be focused
on biological degradation, or biodegradability.
Biodegradability has been defined in several ways. Biodegrada-
tion can be the removal of organic matter from solution by enzy-
matic processes of oxidation and assimilation. Assimilation is the
conversion of organic substances or substrates to new bacterial
protoplasm. Certainly, the word “degrade” means to reduce the
complexity of the substances. If we define biodegradation in terms
of energy, then biodegradation consists of the consumption of a
substance by biological action of living organisms with an accom-
panying degradation of energy. A layman’s definition would be:
An organic substance plus microorganisms yield carbon dioxide,
water, and more organisms.
Note that in none of these definitions were the factors of time
and extent mentioned. In the real world of wastewater treatment,
the extent of biodegradation within a fixed time limit is a very im-
portant consideration to any working definition of biodegradability.
Some researchers prefer not to use the term biodegradability in
connection with wastewater treatment processes. They favor in-
stead the term “treatability” in describing whether a substance is
removed by biological waste treatment processes. The thinking is
that the waste treatment processes place many constraints on the
microorganisms that could prevent a compound from degrading.
This argument is mostly from a scientific rather than practical
point of view. Why are we mainly concerned about biodegrad-
ability? Aren’t we really concerned about the nuisance value of
a new substance and whether it is eliminated by treatment proc-
esses if it finds its way into the wastewater? In principle, labora-
tory testing should show the true biodegradability of the material.
tested as it would occur in the environment or in the waste treat-
ment plants.
Obviously, most substances will ultimately be stabilized by
microbial action, given enough time. We must then consider the
biodegradation process as a rate process. For practical purposes of
wastewater treatment, the substances should degrade at a rate
133
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equal to or less than the normal constituents of domestic waste
after the bacteria have become acclimatized to the substances. In
the activated sludge process, the time limit is 4 to 8 hr. In this
definition, we are comparing one substance with another. The bio-
degradability of a material cannot be expressed as a single absolute
figure, but as a relative figure because of the complexity of the
biological degradation process. Attention should be directed to the
fact that biodegradability is not a measurable property or condi-
tion of the water, but rather a property of the pollutant.
Although we usually think a compound has to be degradable to
be removed by wastewater treatment, it is possible to remove the
compound entirely by flocculation or adsorption. Toilet tissue may
be considered in this category. Although it is slowly degraded by
microorganisms, most of it is removed by sedimentation in the
primary sedimentation tank, or by adsorption on the bacterial floe
in the aeration tank. The activated sludge fioc has great adsorption
properties, and many organic substances are so adsorbed. In most
cases it is true that a compound would be more environmentally
acceptable if it were rapidly degraded by microorganisms.
How biodegradable should a compound be? The possibilities
range all the way from slight to ultimate breakdown of the com-
pound to cell matter, carbon dioxide, and water. Biodegradability
must be measured in terms of its effect on the environment. In
widespread use of a specific compound, a potential exists for sig-
nificant environmental pollution if the compound is not degraded
within a reasonable time in wastewater treatment plants or rivers.
The future would indicate that the environmentally acceptable
biodegradability criterion for products that become waterborne
wastes should be that they are completely degraded to products
that are harmless in surface and drinking waters.
TEST METHODS
Over the years, considerable research has been done on evaluat-
ing microbial breakdown by organic compounds. Techniques have
ranged from Warburg respirometry used by microbiologists to
BOD determinations and laboratory activated sludge units used
by sanitary engineers.
The important feaures and limitations of various methods of
testing biodegradability follow.
River Die-Away
The river die-away method is a very simple method and has
been used by many investigators. The compound to be tested is
added to a sample of river water and left at normal room tempera-
ture. Periodically, the solution is analyzed for the test compound
to establish a die-away or disappearance curve. The curve usually
shows a lag or no degradation for several days and then a rapid
134
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removal when the microorganisms have become acclimatized to
the compound. The advantage of the river die-away test is that
it requires very little equipment and it gives both the rate and
the total degradability of the test material. The rate is only rela
ive; if, after the disappearance of the compound, an additional
amount is added, it will disappear in less time. This can be re-
peated several times so that the die-away curve will have a saw-
toothed appearance. Another modification that can be used to
reduce the lag time and speed the process of acclimatization is to
add a small amount of activated sludge to the river water.
The disadvantage of the test is that all rivers are not the same.
Some have more microorganisms than others, and the pH and
mineral constituents vary. To be able to use this procedure, it is
necessary to be able to analyze for the compound. Likely, the
method of assay will detect the original compound, but not a slight
modification of the compound. Thus intermediate products could
go undetected. In spite of the procedure’s inherent drawbacks, it
is useful in obtaining preliminary information on the ease of
biodegradation. A large number of compounds can be screened in
a relatively short time.
Warburg Respirometer
The disappearance of oxygen as the degradation proceeds is a
general characteristic of aerobic biological systems. The Warburg
respirometer is one of many apparatuses that permit oxygen up-
take rates to be determined for a biological system., The reasons
for its popularity are that it is commercially available, compact,
and permits a number of samples to be run simultaneously.
There are a number of variables that can affect the results, but
the most important factor is the nature and quantity of the micro-
organisms used. The seed used should be one that has become
adapted to the test compound or that has at least been subjected
to an adaptation period: As with any microbial growth system,
the greater the initial number of microorganisms present, the more
rapid the rate of oxygen utilization.
Advantages—
1. Direct measurement of biological oxidation is possible.
2. The method can be used for all compounds without using a
different analytical test procedure. This is a decided advantage
when no good analytical method exists.
3. Results are available within a reasonable time.
4. Oxygen consumption, radioactive carbon dioxide evaluation,
and respiration assimilation balances can serve as bases for meas-
uring biodegradability.
5. The method permits continuous observation of multiple samples
over periods of a few hours or several days.
6. Lag periods and rate changes are readily determined.
135
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Disadvantages—
1. Equipment is fairly expensive and requires a skilled technician.
2. The small sample size makes it difficult to obtain representative
samples of sewage and some industrial wastes.
3. All organic matter added to the system is subject to oxidation,
therefore necessitating pure organic compounds for fundamental
studies.
4. With extended runs, nitrification can occur, giving high, errone-
ous results.
5. Oxygen uptake results are difficult to interpret quantitatively
unless supplemented by other analyses.
Biochemical Oxygen Demand Test
The biochemical oxygen demand test (BOD) is one of the older
methods of evaluating the biodegradability of substances. It was
first published as a standard by the Royal Commission for Sewage
Disposal in 1912. For many years, nothing better was available for
determining the strength and controlling the treatment of waste-
water. In the BOD test, the amount of dissolved oxygen utilized
during 5 days when the sample is stored in a filled bottle in the
dark at 20 C is measured. Instead of a single determination, a
curve of oxygen uptake as a function of time can be developed
if a series of duplicates are run. With the development of reliable
oxygen-sensing probes, it is now possible to determine the oxygen
content at intervals or continuously over the entire test period.
Another modification of the testing apparatus is that the oxygen
uptake and BOD are determined electronically from the electrical
current consumption needed to generate the oxygen required to
maintain the pressure equilibrium in the flask.
The BOD test has numerous limitations when test results are
used to predict what will take place in a waste treatment plant
or in a stream. Only those limitations pertinent, to utilization of
the method for determining biodegradability will be discussed.
Advantages—
1. The apparatus and testing procedure are very simple. The test
does not require a highly trained technician.
2. A large amount of BOD data are available on compounds with
known waste treatability in our present waste treatment systems.
3. The small number of bacterial cells used and the food free BOD
dilution water minimizes interferences with chemical analyses
either for the parent compound or intermediate breakdown
products.
4. Carbon dioxide is present throughout the test period and does
not become limiting as is possible in the Warburg procedure. It
has been reported that complete absence of carbon dioxide inhibits
assimilation of organic matter by bacteria.
136
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5. Problems of aeration and oxygen transfer are not encountered
because all the oxygen required is present at the beginning of the
test.
Disadvantages—
1. The amount of sample that can be used is small because of the
limited solubility of oxygen in water.
2. The testing period is long, although some indication can be ob-
tained in less time if the oxygen uptake is measured periodically.
3. As with the Warburg procedure, nitrification and extraneous
organic matter can lead to erroneous conclusions.
4. The interpretation of results has the same limitations as the
other types of respirometer methods in that results are not directly
convertible to percentage of the compound degraded.
Flask Test Method
The flask test method is the most widely used technique of all
the laboratory procedures except for activated sludge. There are
many versions of the test procedure, but most use a preadapted
seed and a chemically defined medium. The flasks may be aerated
by continuous shaking on a mechanical shaker, agitated with
magnetic stirrers, aerated through a ceramic filter, stirred with a
paddle stirrer, or merely left quiescent. The test mixture can be
analyzed each day or at the end of the specified time period. If
degradation is not evident or toxicity is evident, the test compound
should be run at a lower concentration. Parallel runs with known
degradable compounds are advisable to insure that the test con-
ditions were correct. It is suggested that a compound of similar
structure and class serve as a reference standard.
The popularity of the flask test method is exemplified by the
fact that five leading countries have adopted some version of the
method as their screening or presumptive test method for deter-
mining the biodegradability of anionic detergents.
Advantages —
1. The flask test method does not require elaborate or specialized
laboratory equipment.
2. Reproducibility is generally good.
3. Sample size is not limited.
4. The test compound does not have to be pure.
5. Metabolic products can be studied without too muàh interfer-
ence if mineral salts are used and the test compound is the sole
carbon source.
Disadvantages—
1. The flask test method does not show the time required for
adaptation since an adapted culture is used.
137
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2. A separate adapting process is required if adaptation is not
made a part of the test procedure.
3. Shaking on a mechanical shaker limits the amount of sample
that can be run.
4. No waste treatment process is simulated.
5. A chemical or physical analytical test method must be available
for each class of compounds tested or a material balance must
be run.
6. Simple analytical procedures do not generally measure degrada -.
tion residues.
Activated Sludge Method
The activated sludge process is one of the most important waste-
water treatment processes. Laboratory scale models of the process
have been used for many years to study the treatability of various
industrial wastes. It was natural that the method should become
a major tool in biodegradability testing.
The laboratory methods based on the activated sludge principle
vary in feed, residence time, and type of run (continuous or
batch-fed). The continuous activated sludge system is preferred
because it corresponds more nearly to practical •conditions. A
system that approximates the operation of a plug flow aeration
tank was developed by Butterfield back in 1937. It is known as the
fill-and-draw or the semicontinuous process. In this method of
testing, the bacteria inoculum, the test material, and the feed are
placed in an aerated vessel. The feed is usually a chemically de-
fined medium. The mixture is aerated for a period of time, usually
23 hours. Then the air supply is turned of! and the mixture al-
lowed to settle. A portion of the supernatant is removed and
replaced with new feed containing the test compound. This pro-
cedure is then repeated for the duration of the test. If the test
period is long, it is necessary to periodically waste some activated
sludge to maintain a reasonable level of bacteria. In all aerobic
biological processes there is a net increase in bacterial cells.
Although each cycle in the semicontinuous operation constitutes
a batch run, the method closely approaches plug flow conditions
in a conventional activated sludge plant. The aeration basin of
the activated sludge process is usually long and narrow. The
recycle sludge and the wastewater enter at one end of the aera-
tion tank. Ideally, the mixture moves as a plug the entire length
of the tank. The bacteria are subjected to all phases of the bacterial
growth curve, from the log phase to the endogenous stage. That is,
at the head end of the tank, the bacteria have an ample supply
of food upon which to feed. In this portion of the tank the bacteria
are growing most rapidly, and consequently the removal rate of
the organic matter is the greatest here. As the plug moves along
the tank, the food becomes depleted, and if the retention in the
138
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basin is correct, the bacteria will start to enter the endogenous
phase just as the plug reaches the end of the aeration basin.
The laboratory activated sludge units used by investigators have
varied in capacity from a few hundred milliliters to several gal-
lons, depending on the nature of the study. The volume should
not be too small or sampling would disturb the system. For bio-
degradability testing it is not necessary to maintain a large unit.
Small units are much more desirable because of space, cost, and
labor of servicing several large units. On scaling down to very
small units, there is some difficulty in designing settling chambers.
In most units the settling chambers are an integral part of the
aeration tank rather than separate units. The majority of the
laboratory units are of the completely mixed type rather than
plug flow.
Advantages —.
1. The continuous and the semicontinuous methods simulate in the
laboratory the treatment that wastewater normally receives.
2. There is an accumulation of knowledge over the years since
the method has been used.
3. Reproducibility is very good if the unit is operated until steady
state is achieved.
4. Sample size is not limited.
5. The test compound does not have to be pure.
Disadvantages—
1. Continuous operating units require money, space, and mainte-
nance.
2. Single batch runs do not allow for acclimatization unless the
test period is unduly prolonged.
3. Residence time of 23 hr in the fill-and-draw method is not typ-
ical of treatment plants and is not therefore realistic.
4. Most investigators feel that valid results cannot be obtained in
less than 10 days. There are always unexplainable fluctuations in
the efficiency of the process that must be averaged.
5. A chemical or physical analytical method must be available for
the analysis of each compound if wastewater is used as feed. If
mineral salts medium is used, BOD or COD tests can be used to
calculate a material balance,
FUTURE REQUIREMENTS OF BIODEGRADABILITY
The emphasis on biodegradable materials that emerged around
1960 relative to detergents may be expected to continue. In fact,
the requirements for biodegradable compounds will increase as the
world becomes more conscious of pollution in its waterways.
In the United States, there is no Federal law or regulation re-
139
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quiring that compounds be biodegradable. Several local ordinances
have been passed restricting the sale and use of biologically non-
degradable detergents.
In the future, products that will become a constituent of waste-
water will not receive serious consideration for big markets if
they are not fully biodegradable.
In general, there is still lack of agreement on a standard test
procedure. In fact, there is no satisfactory definition of the term
biodegradable that is acceptable to all. The question concerning
the biological degradability of a compound can only be answered
by a biological test. The structure of a compound can be of assist-
ance in predicting the behavior of the compound, but biodegrad-
ability depends on many factors, such as size of the molecule,
solubility, and surface activity. Predictions are more reliable when
dealing with a homologous series than when making gross com-
parisons based on functional groups or straight chains.
In determining the treatability of waste, the rate and the extent
of degradation must be considered. The rate at which a certain
property of a substance changes as a function of time elapsed is
not difficult to determine. It is the extent of degradability that
poses the problem. There is a need to know if any degradation
products are formed in the process as intermediate or end prod-
ucts. The metabolic products, like other nonbiodegradable pol..
lutants, can build up in the surface water supplies, making them
• undesirable for reuse, or they can build up in food chains, causing
damage to aquatic life.
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RENOVATED WATER FROM MUNICIPAL
SEWAGE TREATMENT PLANTS
Apolinary L. Kowal
ABSTRACT
Renovation of secondary effluent from a trickling filter and an
activated sludge plant were investigated. Coagulation, sedimenta-
tion, recarbonation, filtration, and sorption were applied.
The investigation was performed on both laboratory and pilot
scale. In flow to the sewage treatment plants was characteristic of
municipal sewage. BOD of the inflow ranged from 121 to 360
g/m °2 average treatment efficiency of the trickling filter and
activated sludge plant was 86% removal of BOD, and 37% and
84% removal of ammonia nitrogen, respectively. Ammonia nitro-
gen concentration in the secondary effluent from the activated
sludge plant was relatively low (up to 6.1 g/m 3 N), and very high
in the secondary effluent from the trickling filter plant (up to 26
g/m N. Jar test coagulation of the secondary effluent required
high doses of the coagulants. The coagulant doses were lower when
the process was performed in the sludge blanket clarifier. Lime was
establj$hed as the most economical coagulant. Application of iron
and alum salts resulted in an increase of sulphate, whereas large
doses of lime increased hardness and alkalinity of the water, so that
the recarbonation followed by sedimentation was obligatory. The
best removal of hardness and alkalinity was acquired through a re-
carbonation after coagulation and sedimentation. An optimum dose
of lime to coagulate the activated sludge plant secondary effluent
fluctuated from 200 to 1200 g/m CaO. The higher the concentra-
tion of phosphate and the higher the permanganate values of
treated water, the higher the doses of lime that were required.
The use of fiocculants of domestic production (Rokrysol WF-1
nonionic, WF-2 anionic, WF-3 cationic) improved the effect of
coagulation slightly and mainly aided flocculation and sedimenta-
tion. Sorption on a carbon slurry in simultaneous coagulation and
sorption, or sorption on a carbon filter bed following coagulation,
decreased the permanganate value about 30% compared with
single coagulation. Removal of ammonia nitrogen in all investi-
gated processes was insignificant. The permanganate value of the
renovated water could be lowered up to 5.2 g/m °2’ and phosphate
concentration to 0.07 g/m 3 P. The color and turbidity of renovated
water were close to drinking water standards.
141
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INTRODUCTION
Water renovation of secondary effluent from sewage treatment
plants in Waibrzych (trickling filters and an activated sludge
plant) were investigated. Lime, iron and alum coagulation, sedi-
mentation, recarbonation, filtration, and sorption were employed.
Effectiveness of COD, BOD, phosphate, and turbidity removal was
high. Removal of nitrogen ammonia was insufficient.
About 75 % of water demanded by municipalities and industries
in Poland is supplied from surface water sources. In the year
1990, this proportion will rise to about 85%. The water demand
will approach 30 billion m , an amount equal to the entire dis-
charge of the rivers in a dry year. By the year 1990, with in-
creased industrialization, agricultural production, and demand for
water by the population, much of the surface water can be ex-
pected to be so affected by pollution that present methods of
sewage treatment may not produce the required degree of purity.
The increase in biogenic and refractory substances in surface
waters already limits the possibilities of some waters being util-
ized for municipal and also for industrial supply. Protection
against pollution and improved water quality will require the
application of tertiary treatment of sewage and water renovation
processes.
In many cases, the quality of renovated water is better than
water from polluted rivers. Sanitary, hygienic, and aesthetic con-
siderations and also the increased concentration of refractory and
mineral substances prevent the use of renovated waters for direct
municipal supply without self-purification in a receiving stream.
By using renovated water for industrial supply, the self-purifi-
cation process may be bypassed and waters of drinking quality
will be conserved. This approach has particular significance for
regions experiencing water shortage. The Institute of Environ-
mental Protection Engineering of the Wroclaw Technical Univer-
sity undertook research on the renovation of secondary effluent
from the Walbrzych sewage treatment plants. In 1973 they used
biological filters, and in 1975, an activated sludge plant.
The sewage reaching the plants is predominantly from residen-
tial. areas with a small proportion of sewage from food industries.
The characteristics of influent and secondary effluent are given in
Tables I and 2.
EFFECT OF WATER RENOVATION PROCESSES ON
SECONDARY EFFLUENT FROM A TRICKLING
FILTER PLANT
The investigation of water renovation from the biological filter
effluent was performed on a laboratory and a pilot scale. The
inflow to the trickling filter plant in Walbrzych is characteristic
of municipal sewage. The pH ranged from 7.4 to 7.9, and the alka-
là
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TABLE 1. CHARACTERISTICS OF INFLUENT AND
SECONDARY EFFLUENT FROM A SEWAGE TREATMENT
PLANT (BIOLOGICAL FILTERS) IN WALBRZYCH
Secondary
Influent effluent
Characteristic Mm Max Mean Mm Max Mean
pH 7.4 7.9 7.7 7.4 8.1 7.6
Alkalinity, g/m 3 CaCO 3 280 330 305 165 290 230
Permanganate value, g/m 3 02 33 180 83 8 32 18.4
BOD,g/m O 2 121 360 237 14 58 33
COD, g/m 2 °2
Ammonia, g/m N 32 54 39 12 44 26
Orthophosphate, g/m 3 N 3.8 5.9 4.6 0.7 4.0 2.9
Dissolved solids, g/m M 438 619 529 368 536 475
Suspended solids, g/m 3 62 270 187 2 152 69
TABLE 2. CHARACTERISTICS OF INFLUENT AND
SECONDARY EFFLUENT FROM A SEWAGE TREATMENT
PLANT IN WALBRZYCH (ACTIVATED SLUDGE)
Characteristic
Secondary
Influent effluent
M m
Max
Mean M m
Max Mean
pH
Alkalinity, g/m 3 CaCO 3
Hardness, g/m 3 CaCO 2
Permanganate value, g/m 3 02
BOD, g/m 02
COD, g/m 3 02
Ammonia, g/m 3 N
Total phosphorus, g/m 3 P
Orthophosphate, g/m 3 P
Dissolved solids, g/m ’
Suspended solids, g/m 3
6.5
140
215
64.0
134
121
17.6
1.7
9.9
266
84
9.1
375
645
250.0
640
519
93.0
13.0
13.7
916
11.9
7.4 6.2
295 55
290 210
143.0 4.5
312 8.5
315 41
39.5 0.4
7.7 3.2
5.5 0.7
649 364
433 6
7.8 7.2
225 130
320 245
173.0 21.6
285 43.4
83 56.2
18.6 6.1
7.3 5.3
11.7 4.0
791 559
152 68
linity ranged from 280 to 330 g/m’. The permanganate value stayed
within wide limits, from 33 to 180 g/m 3 02, and the BOlD ranged
from 121 to 360 g/m 3 02. The average ammonia nitrogen concen-
tration was 39 g/m N, and the phosphates were 14.0 g/m PO 4 .
The efficiency of treatment was sufficient to obtain 77.8 % reduc-
tion for the permanganate value, 86.1 % for the BOD, 33 % for
the ammonia nitrogen, and 37.1 % for the phosphate. (Table 1).
In the laboratory tests, the secondary effluent coagulated with
lime or aluminum sulphate was subjected to sedimentation and
then to filtration on a sand bed and through the activated carbon
(Carbon Z-4) filters. When lime was used, the sewage before
143
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filtration was recarbonated with carbon dioxide and again allowed
to settle, The best results in these tests were achieved by a dose
of 1000 g/m Al 3 (SO 4 ) 3 • 181120, which induced reduction of
(a) color intensity from 120 g/m 3 Pt to 20 g/m Pt, (b) permanga-
nate value from 40 to 9 g/m 4 02, and (c) BOD from 140 to 8.8 g/m 3
02. Turbidity was completely removed (Table 3). The use of a dose
amounting to 1600 g/m 3 CaO decreased the color to 10 g/m Pt
and the permanganate value to 13 g/m 3 02. The sewage pH was
about 8.3, alkalinity was 200 g/m 3 , and hardness was 255 g/m 2
(Table 4). The best treatment results in laboratory tests employed
a simultaneous coagulation with a carbon slurry (Carbopol Z-4).
TABLE 3. EFFECT OF ALUM COAGULATION
( 1000 g/m 3 Al 2 ( S04)3 • 18 1120) OF SECONDARY EFFLUENT
Permanganate
Treatment Color, Turbidity, BOD, value
phase g/m Pt g/m 3 5i0 2 pH g/m 2 02 g/m 3 02 % Removal
Secondary
effluent 120 50 8.6 140 40
Coagulation 30 0 6.2 9.6 16.2 60
Filtration 20 0 6.2 17 57
Carbon sorption 20 0 6.7 — 8.8 9.0 77
TABLE 4. EFFECT OF LIME COAGULATION
(1600 g/m 3 CaO) OF SECONDARY EFFLUENT
Color Turbid- Alka- Hard- BOD, Permariganate
value
Treatment gIm ’ p}j unity, ness, g/m 3
g/m 3 g/rn 3 o g/rn 3 Removal
phase
Si0 2 CaCO 3 CaCO 3 2 02
Secondary 120 50 8.6 265 250 140 40
effluent
Coagulation 30 10 12.5 1320 1320 13.2 67
Recarbonation 20 0 8.3 200 315 10.0 14.0 65
Filtration 20 0 8.3 200 315 8.0 13.0. 67
Carbon
sorption 10 0 8.3 200 255 13.0 67
Simultaneous coagulation with an optimum dose of 1000 g/m 8
Al 2 (SO 4 ) 3 18H 2 0 and 800 g/m 3 powdered carbon decreased the
permanganate value from 50 to 4.8 g/m 02 (Table 5) and com-
pletely removed turbidity (Table 6).
In the pilot plant investigations, the secondary effluent was
coagulated with the aluminum sulphate or with lime in a clarifier
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TABLE 5. ALUM COAGULATION (1000 g/m Al:, (SO4): ’ 18H 2 O)
AND CARBON SORPTION OF SECONDARY EFFLUENT*
Carbon dosage, g/m
Color,
g/m 3 Pt
pH
Permanganate value
g/m’ 02
%
Removil
Secondary effluent
100
8.2
50
0
30
5.6
16.2
68
50
15
5.4
12.2
76
100
10
5.5
12.2
76
200
5
5.5
7.8
84
400
0
5.6
6.0
88
800
0
5.6
4.8
90
* Turbidity was reduced to zero by this treatment.
TABLE 6. LIME COAGULATION (800 g/m CaO) AND
CARBON SORPTION OF SECONDARY EFFLUENT
Carbon
dosage, Color,
Turbidity,
Alkalinity,
Permanganate value
% —
g/m g/m 3 Pt
g/m 3
pH
g/m 3 CaCO 3
g/m
02
Removal
Secondary
effluent 30
50
8.0
230
24.4
0 20
0
12.4
490
9.8
61
100 10
0
12.4
350
7.8
72
200 5
0
12.4
340
5.6
78
400 3
0
12.4
280
5.6
78
- 800 3
0
12.4
280
5.6
78
with sludge blanket and then filtered through double media filters
composed of sand-anthracite and of sand-carbon. The output of
the system ranged from 5 x 10 2 m 8 /hr in coagulation with alumi-
num sulphate, and 1 )< 10 t m 3 /hr in coagulation with lime. The
filtration velocity was 5 m/hr. The tests were executed in two
series. The cycle with one dose of coagulant came to 3 days. Re-
sults were given as an average of the two series of measurements.
With a dose of aluminum sulphate amounting to 120 g/m 3 Al 2
(SO 4 ) • 181120, the color decreased from 50 to 12 g/m’ Pt, the
permanganate value from 26.5 to 8.7 g/m 02, and the turbidity
from 30 to 6 g/m 3 S10 2 (Table 7). The ammonia nitrogen was not
significantly removed. A dose of 600 g/m CaO decreased the color
from 50 to 13.3 g/m 3 Pt when filtered on the sand-anthracite bed,
and further reduced it to 4.0 g/m 3 Pt when filtered on a sand-
carbon bed. The permanganate value was decreased from 27.1
to 8.7 and to 6.5 g/m 02, respectively. The hardness of the sewage
was very high, up to 1305 g/m 8 (Table 7).
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TABLE 7. EFFECTIVENESS OF COAGULATION, SORPTION, AND FILTRATION OF SECONDARY
EFFLUENT IN PILOT PLANT
Dosage,
Treatment phase Coagulant g/m 3
Color,
g/nf Pt
Turbidity, Hardness,
g/m 3 SiO 2 g/m 3 CaCO 3
Permanganate value
Ammonia,
g/m 8
02
%
Removal
g/m 3
N
Secondary
effluent 60 22 8 26.0 27.6
Coagulation Al 2 (SO 4 ) 3 ’ 18I1 O 11 8 18.0 28.1 21.0
Filtration 5 3 11.5 54.0 13.6
Secondary
effluent 50 30 26.5 40.1
Coagulation Al 2 (SO 4 ) 3 ’ 18H 2 0 120 40 24 15.5 49.1 35.7
Filtration 12 6 8.7 67.0 27.1
Secondary
effluent 25 8 36.0 13.7
Coagulation Al 2 (SO 4 ) 3 ’ 18H 2 O 200 10 4 25.0 31.2 22.0
t Filtration 9 3 17.5 51.5 15.2
0 ) -
Secondary
effluent 47.5 44.3 225 38.3 57.3
Coagulation CaO 200 33.5 27.7 260 21.4 34.3 53.6
Filtration 22.7 14.7 230 17.5 50.9 48 ,5
Sorption 26.0 14.0 225 12.3 68.1 52.0
Secondary
effluent 50.05 50.0 230 45.0 98.0
Coagulation CaO 400 27.0 28.0 335 18.7 5&4 80.0
Filtration 21.0 8.0 295 18.6 58.4 74.0
Sorption 19.0 8.0 285 18.3 68.3 82.0
Secondary
effluent 50.0 50.0 220 27.1 66.6
Coagulation CaO 600 13.3 10.0 1305 8.5 69.0 56.0
Filtration 13.3 3.0 1290 8.7 68.0 54.8
Sorption 4.0 3.4 1290 6.5 76.0 55.2
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EFFECT OF WATER RENOVATION PROCESSES ON
SECONDARY EFFLUENT FROM AN ACTIVATED
SLUDGE PLANT
The sewage treatment plant is newly constructed. Incoming
sewage is comminuted, treated in sand traps, primary sedimentü-
tion tanks, and activated sludge tanks with a high-rate aeration
system, and finally settled. Average flow fluctuated during the
study from 502 to 1148 m 3 /hr. The average permanganate value
of the sewage was 143 g/m t 02. The efficiency of sewage treatment
was 84.9 % reduction of permanganate value, 86.1 % of BOD, and
82.1 % of COD (Table 2). The effects of coagulation on the sec-
ondary effluent with ferric sulphate, aluminum sulphate, and lime
were determined in laboratory tests performed in 1975. The sew-
age, after jar test coagulation, was settled for 1 hr, and the super-
natant was decanted and analyzed. The optimum dose of lime
ranged from 200 to 1200 g/m CaO. The coagulation of secondary
effluent with a dose of 1200 g/m CaO decreased the permanganate
value from 34 to 18.4 g/m 02 and removed the phosphate and
turbidity. High concentrations of phosphates or high permanganate
value of the secondary effluent required high doses of lime, up
to 1200 g/m CaO; whereas with low permanganate values and
low concentrations of phosphates, the dose was close to 200 g/m 3
CaO. The average and the extreme concentrations of the charac-
teristics of the renovated water are given in Table 8. Use of the
TABLE 8. CHARACTERISTICS OF SECONDARY
EFFLUENT BEFORE AND AFTER LIME COAGULATION
Secondary
Characteristic
Unit
effluent
CaO
Coagulation
Mm
Max Mean
Mm
Max
Mean
pH
8.2
8.6 8.3
11.0
12.5
11.6
Permanganate
value
g/m 02
11.2
34 .0 18.9
5.1
18.4
8.8
Orthophosphate
g/m 8 P
0.91
5.2 2.54
0.00
0.13
0.06
Color
g/m Pt
8
50 35.7
0
25
14
Turbidity
g/m
5
30 18.7
0
0
0
flocculants Rokrysol WF-1 (nonionic polyelectrolyte), Rokrysol
WF-2 (anionic), and Rokrysol WF-3 (cationic) only slightly im-
proved the effects, aiding only flocculation. All the samples coagu-
lated with flocculants had a high opalescence. The recarbonation
of water coagulated with lime was achieved with the use of carbon
dioxide in the following variants:
A. The carbon dioxide was brought to the water and coagulated
with lime after 3 mm of rapid mixing. Then after the pH
reached 8.3, the water was mixed slowly for 20 mm, settled
for 1 hr, and decanted.
147
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B. The process of recarbonation was carried out simultaneously
with dosing the lime, thus maintaining a constant pH of 9.
C. After coagulation and sedimentation, the water was recar-
bonated, settled, and then again decanted.
D. After the coagulation and decantation, 15 g/m 3 of Rokrysol
WF-l was added to the sample; following this, it was re-
carbonated and sedimented, as in test C.
The best hardness and alkalinity removal were acquired through
recarbonation after coagulation and sedimentation. The hardness
of water after recarbonation was lower than the hardness of
secondary effluent. A raised permanganate value was ascertained
in all samples of recarbonated water. The concentration of phos
phates decreased only in Willow Method C. The turbidity of water
from precipitation of fine crystalline calcium carbonate was higher
in all samples than the turbidity in a coagulated sample alone
(Table 9). Coagulation with a dose of 400 g/m 3 Al 2 (SO 4 ) . 18H 2 0
at a variable pH (from 5.9 to 7.8) decreased the permanganate
value from 16.0 to about 7 g/m 3 02. The best results were achieved
TABLE 9. EFFECT OF LIME COAGULATION AND
RECARBONATION ON SECONDARY EFFLUENT
Characteristic
Lime
Sec- coagu-
ondary lation
Unit effluent alone
Recarbonation
(1200 g/m 1 CaO)
method
A B C
D
pH
. 7.4 12.5
8.3 8.9 8.3
8.4
Permanganate
value
g/m 3 0,, 18 8.8
12.8 12.0 10.8
11.6
Orthophosphate
g/m 3 P 8.9 0.2
0.2 0.78 0.00
0.20
Color
g/m Pt 28 15
25 25 16
15
Turbidity
g/m 4 30 0
15 20 30
30
Ammonia
g/m N 11.6 10.9
11.6 9.5 10.5
9.8
Alkalinity
g/m 8 CaCO 3 150 1500
280 250 180
200
Hardness
g/m 3 CaCO 3 2050 2070
340 255 190
195
using a pH of 6.3 to 7.0. Phosphates were removed by 97 %, and
the removal level was independent of the water pH. Turbidity
was removed completely. Concentration of residual aluminum
fluctuated from 0.05 to 1.8 g/m 3 Al. Average and extreme values
for secondary effluent characteristics coagulated with the optimum
doses of ferric or aluminum sulphate are listed in Table 10. The op-
timum sulphate dose of 400 g/m 4 Al 2 (SO 4 ) 3 • 18H 2 0 reduced the
permanganate value from 37 % to 72 %, phosphates by more than
98 ¶%/ , and color from 38 % to 49 %. Turbidity was completely re-
moved. Average concentration of aluminum in samples coagulated
with the optimum dose was 0.65 g/m 3 Al (Table 10). The use of
the polyelectrolytes Rokrysol WF-1, WF-2, WF-3, and Gigtar with
148
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TABLE 10. CHARACTERISTICS OF SECONDARY EFFLUENT BEFORE AND AFTER IRON AND
ALUM SALTS COAGULATION
Characteristic.
Unit
Secondary
—_effluent
Coagulant
Fe 2 (SO 4 ) 3 ’
with
9H 2 0
Coagulant
Al 9 (SO 4 ) 3 ’
with
18H 2 0
Mm
Max
Mean
M m Max
Mean
—
Mm Max
Mean
pH
pH
7.2
8.3
7.8
6.8 7.7
7.2
6.9 7.7
7.6
Permanganate
value
g/m 3 02
14.2
23.2
17.3
4.6 8.2
6.1
4.8 9.0
6.8
Orthophosphate
glut 3 P
2.5
3.3
2.9
0.03 0.06
0.03
0.03 0.09
0.05
Color
g/m 3 Pt
16
35
27
5 26
15
5 18
12
Turbidity
g/m 3
20
30
28
0 0
0
0 0
0
Aluminum
g/m 3 Al
0.0
0.3
0.06
...... ..
0.05 1.8
0.65
Iron
glm 3 Fe —
0.2
0.89
0.29
0.31 0.89
0.50
a
‘ C
-------
100 g/m 3 Al 2 (SO 4 ) • 18 1120 did not improve the effectiveness of
the process, whereas the concentration of aluminum increased
slightly. Coagulation with 100 g/m Fe 2 (SO.j 3 • 9H 2 0 and with
pH 2.9 to 7.4 induced a decrease in permanganate value from 44 %
to 55 %, and in phosphates from 94 r/ to 96 % (i.e., from 0.2 to 0.3
g/m 3 P0 4 -1. The lowest concentration of iron was attained by a
pH higher than 7.4. Coagulation with an optimum dose of ferric
sulphate amounting to 200 g/m 1 Fe 2 (SO 4 ),, • 9H 2 0 decreased the
permanganate value from 42 ‘ /r to 78 % and the phosphates by
more than 98 %. Turbidity was totally removed. The concentration
of iron in samples did not exceed 0.89 g/m 3 Fe. The use of the
polyelectrolytes Rokrysol WF-1, WF-2, WF-3, and Gigtar induced
an insignificant improvement in the level of permanganate re-
moval. Large doses of cationic WF-3 affected the removal of
phosphates and iron in the coagulated water.
DISCUSSION
The coagulation of secondary effluent from biological filters re-
quired high doses of coagulants and high doses of powdered
activated carbon as a result of a high concentration of dissolved
organic compounds biologically undegradable. The proportion of
the permanganate value to BOD of secondary effluent during the
tests was about 0.73. The employment of a clarifier with sludge
blanket increased the contact with a precipitated coagulant and
gave good results in treatment efficiency, with doses of coagulants
lower than in the jar tests. An optimum dose of lime used to
coagulate the secondary effluent from the activated sludge plant
fluctuated from 200 to 1200 g/m CaO. In the water with a high
permanganate value or with high concentration of phosphates,
the dose approached 1200 g/m 3 CaO. The use of higher lime
doses allowed the removal of phosphates; the permanganate value
however was relatively high. High doses of lime increased the
hardness and alkalinity of the water. Recarbonation decreased
hardness, alkalinity, and pH. Increased turbidity was caused by
a fine-grained crystalline calcium carbonate. Coagulation of the
latter with a freshly precipitated sediment decreases pollutant
removal.
A simultaneous coagulation and recarbonation did not improve
the effect of treatment. Changes in the sewage reactions from
pH 5.9 to 7.8 in coagulation with aluminum sulphate, and from
pH 2.9 to 7.4 in coagulation with ferric sulphate had no clear
influence on the effects of pollutant removal, with the exception
of the color. Lowering the phosphate concentration to below 0.2
g/m 3 P0 ; 3 required a fourfold excess of aluminum or iron ions
in proportion to the initial concentration of the phosphates. The
use of ferric or aluminum sulphate for coagulation resulted in an
increased concentration of dissolved solids.
150
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WASTEWATER REUSE PRACTICE IN THE
UNITED STATES
Carl A. Brunner
ABSTRACT
Wastewater reuse in the United States is presently being prac-
ticed for agricultural, industrial, and recreational purposes. One
example of nonpotable domestic reuse exists, but at this time there
are no examples of potable domestic reuse. As of 1971, the volume
of water reused was 133 billion gal per year. Nearly 58% of this
volume was used for irrigation. Most of the remainder was used
for cooling water.
BACKGROUND
Sound management of water resources must include considera-
tion of the potential reuse of properly treated municipal waste-
water as an alternative for meeting future water demands. Though
the need for additional water supplies is greatest in the arid
Southwest, some areas in the eastern part of the United States are
also observing water shortages. Groundwater in many places is
being mined or used faster than it is being replaced by natural
means. In groundwater-using areas such as Southern California
and Long Island, alternative methods of obtaining water are very
expensive. Where the cos4 sf new water sources is high or where
legal constraints are placed on new sources, wastewater reuse
may be an attractive alternative. The potential benefits of waste-
water reuse were recognized in Public Law 92-500, the Federal
Water Pollution Control Act Amendments of 1972, and more re-
cently in the Safe Drinking Water Act of 1974. There is a clear
national mandate to conserve our water resources by renovating
and reusing wastewater.
Possible wastewater reuse applications include irrigation and
other agricultural uses; industrial uses such as cooling water,
process water, and boiler feed water; use in recreational lakes;
use for fish propagation; and use for nonpotable and potable do-
mestic purposes. All but potable reuse are practiced in the United
States, although use for fish propagation is very limited. The
degree of sophistication of wastewater treatment varies with the
151
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reuse application from conventional secondary treatment (or in
some cases primary treatment) to rather elaborate advanced
systems.
The following information is derived largely from a survey of
reuse made for the Environmental Protection Agency (EPA) by
Schmidt and Clements (Schmidt, C. J., Clements, E. V., “Demon-
strated Technology and Research Needs for Reuse of Municipal
Wastewater,” EPA-670/2-75-038, May 1975.) Data were collected
during the period 197 1-73.
IRRIGATION
According to the EPA survey, of the 133 billion gal water reused
in 1971, 77 billion gal, or 58 %, was for agricultural purposes.
Practically all of the 77 billion gal was for irrigation. The number
of plants utilizing their wastewater for irrigation at that time was
337, but 205 of these were on a very small scale. Irrigation appli-
cations included agricultural crops, pasture land, turf, and land-
scape.
The type of treatment given to municipal wastewater before
utilization for irrigation varies from primary to tertiary. Table 1
shows the distribution of treatment methods. For many crops,
primary treatment is all that is necessary. The majority of plants
do, however, provide secondary treatment.
TABLE 1. MUNICIPAL TREATMENT PROVIDED FOR
IRRIGATION REUSE ON SPECIFIC CROPS
Crop
Number of
treatment
plants*
Treatment level (% of plants)
Primary
Secondary
Tertiary
Grain
17
23
77
0
Corn
11
36
64
0
Vegetables
6
14
86
0
Fruit
12
18
82
0
Cotton
26
29
71
0
Fodder
51
24
73
3
Pasture
34
20
71
9
Turf and landscape 47
9
70
21
* Certain plants supply water to more than one crop.
Distance from treatment plant to point of reuse is an important
economic consideration. In the case of irrigation, 1971 results indi-
cated that 20% of the users were located adjacent to the treatment
plant, and fewer than 6 % were more than 4 mi away.
Wastewater is made available for irrigation primarily as a means
of disposal, not for economic gain. Only a small percentage of
producers charge users, and these charges are generally much
152
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less than the cost of treatment. Any payment is, however, to the
benefit of the municipality, assuming the irrigation use does not
increase the degree of treatment provided.
INDUSTRIAL REUSE
The EPA survey indicated that industrial reuse amounted to
53.5 billion gal/year, or 40 % of the total water reused. One user,
Bethlehem Steel in Baltimore, Maryland, accounted for 44 billion
gal/year. There were a total of 15 treatment plants producing
water for industrial reuse. The total volume for this reuse appli-
cation will increase substantially since at least one renovation
plant is presently being constructed, that at Contra Costa, Cali-
fornia.
Utilization for cooling water represents by far the largest in-
dustrial reuse—more than 98%. Of the 15 industrial reuse facili-
ties, 12 are primarily for cooling.
The degree of treatment needed for cooling water depends on
whether the cooling system is once through or recirculating. For
once through systems, high quality seëbndary treatment is a mini-
mum requirement. Table 2 shows the type of treatment required in
five recirculating systems.
TABLE 2. EFFLUENT QUALITY VERSUS USER TREAT-
MENT REQUiRED FOR COOLING TOWER MAKEUP WATER
Effluent quality, mg/l User treatment
Selected users BOD SS TDS processes
City of Burbank, 2 2 500 Shock chlorination, pH
California adjustment, corrosion
inhibitor
Nevada Power Co., 20 20 1,000- Shock chlorination,
Las Vegas, Nevada 1,500 limeclarification, pH
adjustment, corrosion
inhibitor
Southwestern Public 10 15 1,400 Lime clarification, pH
Service Company, adjustment, shock
Amarillo, Texas chlorination, corrosion
inhibitor
City of Denton, 30 30 130 Shock chlorination, pH
Texas adjustment, corrosion
+ inhibitor (treatment
insufficient for effluent
of this quality)
El Paso Products Co., 10 13 1,300 Lime clarification, pH
Odeása, Texas adjustment, filtration,
softening
153
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Three industrial plants utilize wastewater for boiler water
makeup. Each user provides substantial additional treatment, as
shown in Table 3.
TABLE 3. COMPARISON OF TREATMENT PROCESSES
UTILIZED FOR PRODUCING BOILER FEED MAKEUP
WATER FROM MUNICIPAL SEWAGE EFFLUENT
Company and
boiler pressure
Treatment processes
Product water
quality, ppm as
CaCO 3
Cosden Oil
Hot process lime clarifica-
TDS, 443;
& Chemical Co.,
tion, anthracite filtration,
hardness 1 0-2
Big Spring, Texas
hot zeolite softening, and
(175 psig boilers)
deaeration.
El Paso Products
Cold lime clarification,
TDS, 1,000;
Co., Odessa, Texas
recarbonation, anthracite,
hardness, 0-2
(200 psig boilers)
filtration, zeolite softening,
and deaeration.
El Paso Products
All of above for low
TDS, 0-2;
Co., Odessa, Texas
pressure boilers plus demin-
hardness, 0
(650 psig boilers)
eralization through cation
and anion exchangers.
Southwestern Public
Cold lime clarification, pH
TDS, 0-1;
Service Co.,
adjustment, reverse osmosis,
hardness, 0
Lubbock, Texas
followed by demineraliza-
(1,500 psig boilers)
tion with cation and anion
exchangers, and a mixed
bed exchanger for final
polishing.
Three plants reported using wastewater for processing purposes.
All were in the mining and steelmaking industries and did not
require particularly high quality water.
In most cases of industrial reuse, this source is used because it
is cheaper than alternative sources. As in the case of irrigation
reuse, municipalities selling the water charge only a small fraction
of the cost of. treatment. The highest value reported was 14.4?!
1000 gal. In none of the 15 cases, however, do the municipalities
provide treatment beyond that required for surface discharges.
Substantial additional treatment is provided by the user in some
cases (see Table 3). For cooling water, these additional treatment
costs vary from 10*/1000 gal to 55?!1000 gal. One reported cost
for boiler water makeup was 74#/1000 gal.
RECREATIONAL REUSE
The use of properly treated municipal wastewater to create
recreational lakes has been carried out in at least three instances
154
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in the State of California. The oldest of these lakes is at Santee.
Another is Indian Creek Reservoir, which receives the highly
treated effluent from the South Tahoe plant. The third is at
Lancaster in Los Angeles County.
Treatment beyond conventional organic removal is necessary
for recreational reuse. It is essential that the oxygen demand be
maintained low enough to sustain the necessary dissolved oxygen,
that nutrients be kept below levels causing excessive algal blooms,
that ammonia be almost totally absent, that pathogens be essen-
tially absent, and that any toxic substances be kept at very low
levels. At Santee, water (usually of satisfactory quality) is ob-
tained by lagoon-treating activated sludge effluent, percolating
through natural gravel beds, and chlorinating. The South Tahoe
treatment system includes activated sludge followed by two-stage
lime treatment, ammonia stripping, filtration, carbon treatment,
and chlorination. The Lancaster system includes oxidation ponds,
chemical treatment with alum, filtration, and chlorination, Some
typical values of important effluent parameters are shown in
Table 4.
TABLE 4. TYPICAL PERFORMANCE OF PLANTS PRO-
DUCING RECREATIONAL WATER FROM WASTEWATER
Parameter
Santee
Tahoe Lancaster
Turbidity, JTU
5
0.3 - b.5
1.5
Ammonia nitrogen, mg/l
0.4
23 -35
1.0
Nitrate nitrogen, mg/i
1.0
0.1 - 0.9
1.9
BOD, mg/l
3.5
0.7 - 3.2
0.4
Total phosphorus, mg/i
3.6
0.2 - 0.4
0.29
Coliforms, MPN/l00 ml
<
2
C 2
<
2.2
The cost for treatment by these plants varies widely. The mini-
mum cost of lSçt/1000 gal was reported at Lancaster in 1971. The
reported cost at Santee was 45#/1000 gal, and at Tahoe, it was
88 ?/1000 gal.
In all cases, the water from the lakes is further used in varying
degrees for irrigation.
DOMESTIC REUSE
The capability of reusing wastewater for all domestic purposes
has a number of important advantages over lower quality reuses.
The most significant advantage is the ability to transport the water
to be reused in the same distribution system as the original water
supply. The necessity of providing a separate distribution system
has undoubtedly had a very restrictive effect on reuse.
In the United States no reuse system has yet been developed
that has been approved for deliberate potable reuse. The ability to
155
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treat wastewater to a high degree of purity exists, but there are
no clearcut standards of potability with which to compare the
quality of the water. U.S. drinking water standards are not pres-
ently complete enough to be utilized with a renovated wastewater.
The two types of contaminant groups that present the greatest
problems in potable reuse are trace organics and pathogens, espe-
cially viruses. Fortunately, progress is being made in developing
analytical techniques for both trace organics and viruses. As a
result, answers are beginning to be obtained to the questions raised
by public health authorities concerning potable reuse.
A number of water-short communities have expressed interest
in potable reuse. Denver, Colorado, has taken the greatest initia-
tive toward reuse, including construction of a 1-mgd pilot plant
by 1980. Assuming favorable results, they plan to implement large-
scale reuse by 1990.
The only recognized potable reuse plant in the whole world is
that at Windhoek, South-West Africa. This plant has operated in-
termittently for more than 5 years. Although there have been
plant operating problems, there is no evidence that the product
water has been responsible for any health problems. Public health
authorities in the United States have not placed much reliance
on the results of the Windhoek experience. They generally express
the opinion that much more information on water quality and
system reliability is needed.
The true driving force that will eventually bring about reuse is
economics. When the cost of renovating wastewater becomes
measurably less than the cost of alternative sources, interest will
increase rapidly. At present, even in many arid areas, reasonably
priced alternative sources have not been exhausted. An ongoing
study of a number of specific cases is providing interesting infor-
mation concerning conditions conducive to reuse. It appears under
present economic conditions that reuse will not usually be compet-
itive with water imported in large aqueduct systems. The most
favorable situation for reuse is in areas of low rainfall where the
water supply is from wells. In the arid Southwest it is common
for communities using wells to be withdrawing water faster than
it is being recharged. It is in these communities that reuse is likely
to be required. In addition, there are cases such as Denver, Colo-
rado, and even some cities in the humid eastern part of the country
that, because of local conditions, may have to consider reuse.
156
*USGPO: 1976 — 657.691/1312 Rsglon 5-It
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