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Region III Library
Environmental Protection Agency
Proceedings of the
1977 National Conference on
Treatment and Disposal of
Industrial Wastewaters and
Residues
April 26-28, 1977
Houston, Texas
Sponsored by:
American Institute of Chemical
Engineers (South Texas Section)
Gulf Coast Waste Disposal Authority
Information Transfer Inc.
U.S. Environmental Protection Agency
University of Houston
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Printed in United States of America
Library of Congress Catalog No. 77-89134
Copyright® 1977
by
Information Transfer, Inc.
1160 Rockville Pike
Rockville, Maryland 20852
All Rights Reserved
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CONTENTS
Putting the Environmental Puzzle Together
Stephen J. Gage 1
PCB Distribution in Sewage Wastes and Their Environmental and
Community Effects
A. K. Bergh 4
Safe Disposal of PCB's
Myron W. Black 7
Pros and Cons of Waste Disposal Alternatives
Alan MacGregor and Amir A. Metry 11
Practical Problems in the Operation of a Hazardous Waste Disposal
Site
Michael Crafton and Edward Kleppinger 15
Effluent Disposal in a Surface Pond Lined with Spent Charcoal &
Diatomacious Earth from Beeswax Bleaching Plant
Irving Deutsch and Douglas G. Fronmuller 19
Fly Ash Disposal System
Douglas M. McBean, Laurance C. Tollman, and Raymond J. Hasenauer 25
An Evaluation of Atmospheric Evaporation for Treating Wood
Preserving Wastes
Pete A. Shack 29
Disposal of Particulate Waste From an Air Pollution Cleaning
System
Murali D. Atluru and Abdul Quadir 34
Joint Incineration of High Grease and High Metal Sludges from
Treatment of Municipal and Industrial Wastes—Detroit, Michigan
A. C. Davanzo 39
Putting Activated Carbon in Perspective to 1983 Guidelines
Davis L. Ford 48
Reductive Degradation for the Treatment of Chlorinated
Pesticide Containing Wastewaters
K. H. Sweeny 56
Biological Treatment of Concentrated Nitrate Waste
F. E. Clark, J. M. Napier, and R. B. Bustamante 60
Settleability of Industrial Wastes and Their Energy Values
C. H. Rhee and A. Z. Sycip 67
Treatment of Industrial Wastes from Airport and Airplane
Maintenance—A Pilot Study
Moshe Uziel and William Strangio 78
A Color Removal Process for a Neutral Sulfite Semi-Chemical
Pulp Waste
James S. Taylor and John Zoltek, Jr 90
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Polyester Encapsulation of Hazardous Industrial Wastes
R. V. Subramanian, Wen-Pao Wu, R. Mahalingam, and M. Juloori 97
Pilot Plant Studies on the Polyester Encapsulation Process for
Hazardous Wastes
R. Mahalingam, M. Juloori, R. V. Subramanian, and Wen-Pao Wu 107
Hydrogen Peroxide for Industrial Wastewater Pollution Control
W. G. Strunk 119
Impacts of the Disposal of Heavy Metals in Residues on Land
and Crops
J. F. Parr, E. Epstein, R. L. Chaney, and G. B. Wilson 126
Disposal and Alternate Uses of High Ash Papermill Sludge
John S. Perry and Dean I. Schultz 134
Environmental Assessment of the Disposal of Industrial Wastewater
Residuals in a Sanitary Landfill
Daniel J. McCabe 146
Land Disposal of Acidic Basic and Salty Wastes From Industries
Dhiraj Pal, M. R. Overcash, and P. W. Westerman 151
The Combination of Flue-Gas Desulfurization Sludges and
Municipal Waste to Produce Fertile Soils
Robert W. Briggs, Robert C. Freas, and Laszlo Pasztor 160
Ammonia Removal from Sanitary Landfill Leachate by
Chemical/Physical Biological Treatment
R. L. Steiner, A. A. Fungaroli, and John D. Keenan 166
Disinfection of Treated Landfill Leachate Using Sodium
Hypochlorite
Chongrak Polprasert and Dale A. Carlson 177
Development of Standardized Procedures for Leachate Generation
H. I. Abelson, W. C. Lowenbach, and F. Ellerbusch 189
Land Cultivation of Industrial Wastewaters and Sludges
H. T. Phung, D. E. Ross, and R. E. Landreth 192
A Non-Hazardous, Simple and Economical Method for the Disposal
of Metal Sludges, Using a Segregated Landfill
L. E. Lancy 198
Resource-Conservation Pollution Control Technology: An Idea
Whose Time Has Come
Joseph T. Ling 203
Wastewater Treatment Utilizing Water Hyacinths
B. C. Wolverton and Rebecca C. McDonald 206
Suitability of Clay Beds for Storage of Industrial Solid Wastes
Earnest F. Gloyna and Robert L. Sanks 210
A Nitrate-Removal Ion-Exchange Process with a Land-Disposal
Regenerant
Dennis A. Clifford and Walter J. Weber, Jr 217
Solid-Liquid Wastes from Coal Conversion Processes and Control
Technology
Subhash S. Patel and V. Bruce May 227
Treatment of Solid Residues from Coal Gasification
Charles E. McKnight 234
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EPA's Research and Development Program for the Nonferrous
Metals Industry
George S. Thompson, Jr 244
Leaching Studies and Cation Exchange Properties of Coal Fly Ash
John F. Gaasch and Kam S. Law 246
The Removal of 2,4,6-Trinitrotoluene (TNT) from Aqueous
Solution with Surfactants
Y. Okamoto, E. J. Chou, J. Wang, and M. Roth 250
An Industrial Residue Management System for Allegheny County,
Pennsylvania—Part I
Donald Berman, Edward J. Martin, and Joseph David, Jr 255
An Industrial Residue Management System for Allegheny County,
Pennsylvania—Part II
Edward J. Martin, David L. Guthrie, and Donald Berman 266
The Generation and Disposal of Hazardous Wastes in
Massachusetts
Paul F. Fennelly, Mary Anne Chillingworth, Peter D. Spawn,
Mark /. Bornstein, and Hans /. Bonne 277
Development of a Regional Industrial Waste Treatment Facility
Walter J. Bishop, Ronald J. Calkins, and Joseph Borgerding 283
A Viable Design for a Regional Industrial Waste Treatment
Facility
Bruno Loran 292
EPA's Combined Wastes Program Residual Management Studies
Thomas E. Short, Jr 295
Dynamic Programming Approach to Cost Effective Industrial
Wastewater Treatment Alternative Selection
Kent E. Patterson 301
Financial Planning of Industrial Pollution Control Facilities
Thomas L. Davis and A. F. Miorin 314
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Putting the Environmental
Puzzle Together
Stephen J. Gage
Office of Energy, Minerals and Industry
Environmental Protection Agency
Washington, D.C.
With the interplanetary orientation of Houston I can't help
but think back to July, 1976 when, as we were celebrating the
nation's 200th birthday, we landed two Viking spacecraft on
Mars. That still impresses me as being perhaps our most
inspired, and inspiring, space shot to date.
I remember getting home in time to see the seven o'clock news.
I turned my television set on and was astonished to see detailed,
crisp color pictures of Mars.
Mars.
It was incredible. The soil was a rust color and covered with
crushed rocks. Other pictures showed evidence of massive
erosion and huge flood plains. The landscape was totally bleak
and without a sign of life. The sky was red.
And you think we've got environmental problems!
1 sometimes wonder what would happen if it were the other
way around. I mean, if a pair of Viking spacecraft from another
civilization were to land on the earth. If they were lucky, one of
the crafts would land at a spot where they could study our
technology, and the other would land where they could study
our culture.
For instance, the first craft might land within sight of that
monument to energy and environmental technology—the
cooling tower. And the second might land close enough to this
conference hall to monitor my speech to you today.
If that happened, the alien scientists would obviously con-
clude from their data that Earth was in the formative stages and
was venting great volumes of hot gasses.
What is less certain, however, is whether or not the aliens
would conclude that there was intelligent life on our planet.
On a more serious note, being here in Space City set me to
thinking about the impact that the space program has had. Not
only in terms of technology and knowledge, but also in terms of
a new perspective—of sharing a small blue marble with finite
size and resources, of breathing from a thin fragile blanket of air
and of drinking from limited vulnerable lakes and streams.
In preparing my remarks today, it dawned on me that there
might be some logical connection between this perspective of the
planet and the topic that we meet here to discuss. From 200
thousand miles out, the Earth looks so appealingly simple, so
logical and unified. Not at all like the complex patchwork of
oceans and continents, nations and societies, cultures and
institutions, which we see as we observe the planet from up close.
It strikes me that the many physical monuments which mankind
has built on Earth pale by comparison to the variety of social
and economic systems which have been created, reflecting the
tremendous diversity of human experience.
In the areas of our concern—how man relates to his
environment—the situation could not be more complicated. To
the casual observer, environmental policies, legislation and
institutions must appear to be an impossibly complex puzzle. At
the national level, a number of environmental laws have
emerged in the last decade. The National Environmental Policy
Act, the Clean Air Act, the Federal Water Pollution Control
Act, and others have literally changed the way by which we do
business in this country. The last session of Congress provided
two more pieces of the puzzle—the Resource Conservation and
Recovery Act and the Toxic Substances Control Act.
Taken separately, these laws do indeed appear to be a
disconnected patchwork. But, they are not meant to be taken
separately. Like the pieces of a jigsaw puzzle or the patches of a
quilt, they are meant to be fitted together as a whole.
The environmental legislation to date has been aimed at
controlling one or another unfortunate aspect of our technologi-
cal existence—air pollutants or water pollutants or toxic
industrial products or wastes. It is as though in making a
patchwork quilt we controlled the color, size, fabric, strength,
and shape of each individual piece, separately. Controlling all of
the factors wold still not result in a patchwork quilt. Despite all
the individual controls, the pieces probably would not fit
together. Not only would the quilt be an aesthetic disaster, it
probably would not keep you warm either.
The message is clear. Each of our environmental laws, while
well-intentioned and sophisticated, loses- its true significance
when taken out of the broader context. Enforcing the individual
laws will not get us the kind of an improved environment we
seek.
1 am certain that, to many industries, regulatory agencies in
Washington must resemble a gaggle of half-deaf old ladies, each
haggling incessantly over the precise size, shape or color of each
individual patch, with no hope whatsoever for the eventual pro-
duction of the whole quilt.
Yet into our patchwork puzzle we are now fitting new pieces
which, for the first time, can give us more complete policy
handiwork than we have ever had before.
Let's take the energy policy first. Having worked in the Wash-
ington energy policy milieu for the past five years, I find
President Carter's energy proposals very hopeful. Not hopeful
in the sense that these proposals offer unmitigated blessings for
us but hopeful in the sense that, at least, an honest and
comprehensive energy policy has been put forward by the
President. Most importantly, it is a policy which goes to the
heart of the American way of doing business and suggests
strongly that the American way has to change in order to
survive.
The real issue with which we must come to grips is the need to
accelerate an inevitable evolution of our post-industrial lifestyle.
Sooner or later, another oil embargo or price hike would have
driven us to more efficient automobiles. Sooner or later,
1
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2 Environmental Puzzle
dwindling supplies of essential metals and materials would have
driven us to a greater degree of recycling and resource recovery.
Sooner or later, the dramatic rise in cancer incidence would have
driven us to controlling industrial toxicants.
The secret to national survival and sanity and to a reasonably
decent standard of living is not to be victimized, not to be
buffeted from one crisis to another. It is to anticipate these crises
sufficiently in advance to develop the institutional structures
which will then buffer their impact as they arrive. A coal-fired or
nuclear power plant is a massive capital investment- some
costing as much as a billion dollars—and is expected to provide
¦power reliably for over 40 years. Hence, at least 40 year planning
horizons must be used when defining today's power policies.
7 he pollutant impacts from such power plants may be so subtle
that their health effects—such as tumors—are not manifested
for a generation. We must develop rational and effective ways of
dealing with such time horizons.
Let me draw a parallel between the need for environmental
control and the need for alternative sources and uses of energy.
If you knew, forexample, that yourjob regularly exposed you to
a dangerous chemical and that in 20 years there was a high
probability that you would be stricken with cancer would you,
then, choose to wait 15 years before you acted? Of course not.
You'd act tomorrow. With energy, the problem is very much the
same.
Without early action, the energy disease would certainly lead
to debilitating, if not fatal, effects on our Nation. We know,
beyond any doubt, that competition for the world's oil re-
sources within this century will become very intense. If
unchecked, this competition could cause massive disruptions in
the international economy and society. Should we, wait until
1997 before acting? Of course not. We must not be hypnotized
by dates which now seem so far away. Remember, the child
conceived today will not be able to vote in a Presidential election
until after the turn of the century. Time has crept upon us.
With this in mind, I hope we won't waste another year in an
interminable debate over every minor aspect of the President's
Energy Program. It is, after all, the first truly comprehensive
energy policy to be presented. And it will undoubtedly have to
be adjusted time and time again as we learn the exact implica-
tions of its many features.
One of the most important principles of President Carter's
Energy Program is that it recognizes that energy, environment,
and economy are intimately intertwined. The President doesn't
plan to sacrifice any one of the three for the advantage of the
other two. What is so impressive is that he is the first President
who actually realizes that such a sacrifice is impossible. What
affects one of the E's negatively affects all three.
The role of the Environmental Protection Agency in reconcil-
ing energy, environmental, and economic objectives has been
emphasized by the White House. Since 1974, EPA's Office of
Energy, Minerals and Industry has been running a large
interagency research effort to determine the environmental
impacts of, and develop the necessary control technologies for,
domestic energy systems. We act as the central coordinators of
17-agency effort—the largest such Federal Interagency effort in
history.
Since the beginning in 1974, we have placed primary emphasis
on developing methods to extract and burn coal without
sacrificing our health or productive ecosystems. More than half
of the $330-mi!lion appropriated to the program to date has
addressed such coal-related problems. A significant proportion
of these resources have gone to the development and demonstra-
tion of effective methods of removing sulfur from coal either
before, during or after combustion. Through funds transferred
to the Bureau of Mines within the Department of Interior, we
have supported essentially all of the research on the cleanability,
by proven physical means, of most of the major types of coal
being mined today. Through cooperation with the Tennessee
Valley Authority and several private utilities, we have evalu-
ated and demonstrated several viable stack gas desulfurization
technologies. Within my own two laboratories, we have sup-
ported the development of fluidized bed combustion systems for
low-grade fuels and urban wastes.
Increasingly we are turning our attention to the control of the
remaining harmful substances from stack gases of coal-fired
power plants, such as nitrogen oxides and fine particulate
matter.
Our response to the President's new energy program will be to
dramatically increase our efforts to control pollution from coal-
fired power plants. Building on our ongoing activities, we will
undertake new and expended R&D efforts on SOx, NOx, and
fine particulate control. First, we will expand our efforts to
make scrubber technologies available for coal-fired boilers
including both an accelerated technology transfer effort and
demonstration of an advanced scrubber with integrated acid
production and marketing. We will similarly expand our efforts
to bring coal cleaning technologies into wider application for
sulfur control. Second, we will move to the demonstration phase
of several promising control technologies for fine particulate
pollutants. Fine particles from coal combustion are increasingly
becoming suspect as health hazards since they find their way
deep into the lungs. Third, we will redouble our efforts to devel-
op viable methods to control the nitrogen compounds from coal
combustion. Increased ability to control these compounds from
such stationary sources is necessitated by the extreme difficulty
we are encountering in controlling them from automobile and
other mobile sources. If we are to avoid massive increases in
NOx emissions during the next two decades, we must improve
the controls for coal-fired plants.
In addition to using more coal, the President's program calls
for using less energy. That message comes through very clearly.
We are going to cut down on the wasteful extravagant use of
energy wherever we can.
This is where the President's energy program fits together
with the new Resource Conservation and Recovery Act to form
complementary pieces of the same puzzle. Both thrusts are
aimed at making natural resources of this country last longer.
Both are aimed at protecting our quality of life. Both are
intended to change our way of doing business over the long time
horizon with their greatest effects probably not being felt for two
decades. But within these two decades—and that's about the
amount of time it will take for significant changes to occur in
either capital or technological bases—we will see a dramatic
shift toward cleaner and more efficient industries, in terms of
both energy resources and raw materials.
The Clean Air Act and the Federal Water Pollution Control
Act have focused on eliminating discharge of pollutants into our
air and water, respectively. Implementation of these acts has, to
date, focused primarily on end-of-pipe control of pollutants,
rather than on process modifications, to prevent the release of
pollutants into the environment. It is essential that we shift
increasingly toward more fundamental changes which will
minimize not just the amount of pollutants released but also the
amount of material cycling through the process. In the interim,
we must concentrate on recovery and reuse, whenever possible,
of the by-products generated by our pollutant control measures.
We cannot just move pollutants from one media to another,
turning air pollutants into water pollutants, water pollutants
into solid waste disposal problems.
The recently enacted Resource Conservation and Recovery
Act will soon create disincentives to discourage solid waste
discharge and disposal. This means that it will no longer pay to
run industrial processes inefficiently so that they generate great
volumes of solid residues. Similarly, it means that, in general,
solid wastes from pollution control measures will also have to be
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Environmental Puzzle 3
minimized.
In the air/ water/ solid residues puzzle, RCRA was the missing
piece. RCRA will eliminate or seriously curtail solid waste as the
pollutant sink. RCRA creates the incentives for reuse and
recovery of energy and material resources currently latent in the
solid waste. In this conference you'll hear more on the details
and impacts of RCRA on industry from both an environmental
control and conservation standpoint. So, I won't dwell on the
details of the law itself.
Finally, let me point out that one perspective of RCRC is that
it provides "cradle-to-grave" waste management of both re-
sources and pollutants. For example, it gives a new view of
residues as a potential material for feedstock or fuel. Under
RCRA, the pollutant of today may be the resource of tomorrow.
Not all of our efforts at industrial energy conservation and re-
source recovery are in the future. Far from it. In pursuing its
mandate to develop and demonstrate more advanced methods
of controlling the pollution from industrial sources, EPA's
Office of Research and Development has sponsored numerous
projects which have resulted in savings in energy, cost, waste or
all of these. Let me just give you a few examples.
The metal zinc is seldom thought of as one of our major
endangered resources. And yet, the known world reserves are
sufficient for less than 20 years production at present rates.
More than 50 million pounds of zinc sulfate are used annually in
the U.S. in the manufacture of approximately one billion
pounds of viscose rayon. Much of the zinc is lost in the process.
To recover some of this waste we sponsored a demonstration
with the American Enka Company. While the capital and
operating costs of the new recovery systems are higher than for a
conventional system, the value of the zinc recovered creates a
substantial savings. For instance, a 50 million pound/year
industrial yearn operation could actually realize a profit of
nearly $200,000/ year by recovering its zinc. This is, of course, in
addition to avoiding the creation of large volumes of trou-
blesome wastes.
Another successful resource recovery project was conducted
on a nickel plating line in a small electroplating plant in New
England. The project involved the recovery and reuse of nickel
plating solutions by means of electrodialysis. The units recov-
ered 98% of the nickel. Considering both capital and operating
costs, the system will pay for itself within less than two years. At
the same time, the plant will meet its discharge requirements and
eliminate a difficult sludge disposal problem.
There are other examples, much too numerous to describe
here. You'll be hearing of some of these during your meeting.
Now to another piece of the puzzle. While RCRA will
substantially control toxic pollutant discharges in solid waste
materials, it does not address toxic materials in or as products.
That's where the Toxics Substances Control Act of 1976
enters the picture. TSCA will control new toxic chemical
products through registration not unlike those imposed on
foods, drugs, cosmetics and pesticides.
Now, for the first time PPA must examine in-plant sources of
toxic materials that appear in the products themselves as well as
in air, water and solids discharges.
The Environmental Protection Agency is now deeply into the
process of planning the implementation of both RCRA and
TSCA. Numerous intra-agency panels are at work considering
alternative approaches for carrying out the mandates of these
two acts. Input is being sought from interest groups. Slowly the
institutional framework is being put together to manage the
day-to-day business of RCRA and TSCA.
One encouraging development is the realization within EPA
that, somehow, we now must fit the pieces of the puzzle together.
We no longer have any excuses for letting a toe stick out
through the patchwork quilt. But it's not an easy job. The
majority of the technical people in the Agency have typically
worked on environmental problems associated with a single
medium. Organizationally, it's always simpler to ignore the
interactions, to concentrate on streamlining out the critical in-
tegrative functions. But we know we can't do this anymore.
For example, we're attempting to determine how to
coordinate or at least keep informed, the thrusts of the several
regulatory arms within the Agency to regulate toxic substances.
What the Office of Toxic Substances does with a specific
toxicant can and will affect what the Air Program Office does
with that material, or what the Effluent Guidelines Division
does, or, for that matter, what the Office of Research and De-
velopment does. As you can guess, this is a very difficult task.
But it is an absolutely essential one.
These pieces of legislation and policy are slowly being fitted
together. They are forming a cogent set of guidelines which will,
for the first time in human history, consciously redefine the
relationships of the political economy with the natural environ-
ment and resources. This is, indeed, a noble experiment. But its
nobility is somewhat tempered by the practical realization that,
to a great extent, our health and survival, as a species and as a
nation, depend upon a successful outcome.
As to what parts of this puzzle are still missing, it is difficult to
project. One piece, surely, will entail some stimulus to improve
the durability and maintainability of so-called durable goods.
The better each automobile is made, for example, the longer it
will last. The longer it lasts, the less resources will be needed to
"recycle" the automobile when its productive life is over.
Another emerging piece of this puzzle is the fad toward durable,
tough clothing—the outdoors look—is likely to become the
mainstream in dress. And, if durable goods last longer, there will
be less need to replace them for "newer models".
Beyond these few educated guesses, however, the future will
present us with just as many surprises and challenges as the past.
But if, as it now appears, we meet these challenges with wisdom
and enthusiasm, we can be certain that our health, our environ-
ment and the quality of our lives will continue to improve.
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PCB Distribution
in Sewage Wastes
and Their Environmental
and Community Effects
Although polychlorinated biphenyls (PCBs) have been used
in industry since about 1930 because of their exceptional resis-
tance to heat, their fire-retardant properties, and their proper-
ties as electrical insulators, concern about their environmental
effects became prevalent only recently. In Japan, over 1,000
persons developed "Yusho" disease in 1968 when they consumed
rice oil containing high concentrations of PCBs—up to 3,000
parts per million (ppm) of Kanechlor 400'. The PCBs had leaked
into the rice oil from a defective heat-transfer pipe. Persons who
consumed food cooked with the rice oil developed severe skin
acne, darkening of the skin, eye discharges, and ulcers of the
uterus. Stillbirths and miscarriages were also reported. The
Japanese also attributed a number of deaths to PCB poisoning.
To our knowledge, accidental human ingestion of such massive
quantities of PCBs over a short period of time has not been
reported elsewhere; however, there is considerable evidence that
exposure to low levels of PCBs can also be environmentally
devastating.2,3,4
PCBs accumulate in the fatty tissues of life forms exposed to
them and become concentrated more and more as they move up
the biological food chain.5,6 Fish, for instance, caught in waters
containing PCBs in the order of several parts per billion (ppb)
can bioaccumulate the substance to well over 100 ppm. Foods
containing PCBs in excess of 5 ppm are, in general, considered
to be inedible according to current FDA standards.
In one study at the University of Wisconsin, rhesus monkeys
were given food containing 2.5 ppm Aroclor 1248 PCBs.2 The
monkeys developed acne, lost hair, and later developed skin and
liver lesions. Undersized offspring resulted as well as some cases
of fetal resorption.
The PCBs are highly resistant to degradation by biological or
physical means, thereby being among the most environ-
mentally persistent chemical known.7 This lack of
destructability of PCBs renders them rather ideal for the
purposes for which they have been manufactured. On the other
hand, this persistence presents toxicological and ecological
threats not envisaged until recently. Consequently the manufac-
ture and use of PCBs is being phased out in the United States but
the problem will, nevertheless, remain with us for a long time
into the future.
In the Midwestern community under study the decision was
made at the City Central Laboratory during the early fall of 1975
to ascertain if sewage wastes were contaminated by PCBs. While
it was expected that PCBs would be found, no one at the
laboratory was prepared to expect the high concentrations of
PCBs which were indeed found on subsequent analysis. Table I
shows the results from analysis of solid samples, including sewer
bottom sediments, grit chamber solids, and sludge from the
digesters.
A. K. Bergh
Indiana University
Bloomington, Indiana
and
R. S. Peoples
City of Bloomington Utilities
Bloomington, Indiana
Table I: PCB Concentrations in Dried Solid Sewage Sample,
Location
PCB Concentntla.
Range
(ppm)
Sewer sediment 7 miles upstream from sewage
treatment plant
760-950
Grit chamber solids
50-530
Scrapings from trickling filter rocks
220
Supernatant sol Ids from anaerobic digesters
(supernatant 1s recycled to preliminary treatment
stage)
210-260
Sludge from anaerobic digesters
240-1700
Stream sediment below sewage treatment plant
discharge point
4
Stream sediment upstream from sewage treatment plant
discharge
0.6
It was found that dried sewer line sediments collected abort*
seven miles upstream from the sewage treatment plant co*.
tained about 900 ppm PCBs. The sewage treatment plant gHt
chamber solids contained PCB concentrations ranging from So
ppm to over 500 ppm on a dry weight basis. Dried sludge frorn
the anaerobic digesters contained from over 200 ppm to as hi&K
as 1700 ppm PCBs. The mean PCB content of six differed.*
sludge samples—collected at different times—was appro*;/
mately 760 ppm PCBs. The type of PCB found at present i
mainly Aroclor 1016, manufactured by the Monsantocompan*
in St. Louis. Such high concentrations may be contrasted witK
results reported from other U.S. cities. In one report of 16 cities
sewage sludge from only 2 cities exceeded 10 ppm while slug.* *
from 2 others exceeded 5 ppm PCBs." In the current investiga*
tions, stream sediment below the sewage treatment plan"
discharge point contained approximately 4 ppm PCBs while th *
stream sediment upstream from the sewage treatment plan»
contained less than 1 ppm PCBs.
The liquid samples, containing suspended solids, were found
to have quantities of PCBs as shown in Table II.
PCBs are not soluble in water except for microquantitie®
When introduced into a water system the PCBs bccorn
absorbed readily onto silt and other solid particles.' The resuu^
reported in this study demonstrated this sort of behavior. S
For a number of years dried sludge had been given away t
citizens in the district for use as a soil conditioner in the
gardens. When the PCB content of the sludges became known*"
people were invited to submit soil samples to the laboratory ftt*
4
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PCB Distribution 5
analysis. While about 40% of the soil samples contained PCBs in
the 0 to 4 ppm range, 20% ranged from 5 to 20 ppm and about
one-quarter of the soil samples contained PCBs in the 20 to 50
ppm range. A few samples contained higher concentrations of
PCBs. These gardeners and farmers then became faced with the
problem of removing their top soils or closing those areas to
future production of garden products. Some grazing land was
affected too.
Table II: PCB Concentrations in Liquid (with Suspensoids)
Sewage Samples
Location
PCB Concentration
Range
(ppm)
Sewer, entering treatment plant
0.03-0.47
Miliary settling tank effluent
0.07-0.33
Trickling filter effluent
0.05-0.08
Secondary settling tank effluent
0.02-0.05
Stream water immediately below sewage
treatment plant discharge point
0.03
Stream water upstream from sewage treatment
plant discharge point
<10"5
(not detectable)
Fish caught about 9 miles downstream from the sewage
treatment plant were analyzed at a State laboratory.10 PCB
concentrations in the tissues ranged from 50 to over 200 ppm,
rendering the fish inedible. The State Board of Health issued
warnings that fish caught in the stream and in another stream
nearby should not be eaten. The State Board of Health also
found it necessary to ban the sale of milk by certain dairies where
milk was found to contain up to 13 ppm PCBs. Most of the latter
PCBs originated, however, from PCB-containing paint coatings
used to line silos for storage of feed grains. Following the bans, a
bill to assist dairy farmers who are put out of business by PCBs
was introduced and passed in the State Legislature. The bill, at
this stage, did not provide for compensation to municipalities
for fear of killing the entire bill.
In September, 1976, the State Environmental Management
Board commenced legal hearings on the problem. The Board
wanted to determine who was responsible, what damage had
been done, and what the damage was doing to the community.
Both lay and expert witnesses have testified and the hearings are
continuing.
Since the problem became exposed, a number of city sewage
plant workers had small sections of body adipose tissues taken
for analysis. The results showed PCBs in the low ppm range in
the samples. The same workers as well as other city employees
had blood tests and liver biopsies performed by the National
Institute of Occupational Safety and Health (NIOSH). PCBs in
the low ppb range were found. In late January, 1977, many
families in the district signed to receive free physical exam-
inations by U.S. Public Health Service doctors. A medical team
from the federal Communicable Disease Center (CDC) in
Atlanta, Georgia, arrived during the latter part of February,
1977, to set up a testing laboratory at the local hospital in prep-
aration for the medical examinations. Furthermore, at this
writing, the current employees of an electrical manufacturing
plant in the city which has used extensive quantities of PCBs for
use in industrial capacitors, Westinghouse Electric Corpora-
tion, are to be examined by physicians from NIOSH. To date,
medical results or conclusions from these examinations have not
been released.
The dumping of PCBs into the sewer system has posed many
problems for the city, not the least relating to the question of
sludge removal. Landfills in the area are unsuitable. Leachates
from existing landfills have been shown to reach creeks in the
district. At present, as a temporary measure, the city is paying a
private company to haul the sludge to a hydrologically isolated
landfill in Illinois. Meanwhile, alternative and economically
bearable means of disposal are being studied. Those include:
1. Continuation of the practice of hauling the sludge
2. Incineration of the sludge
3. Encapsulation of PCBs in the sludge
Some of the drawbacks to the above methods are:
1. Hauling is expensive. Also the hydrologically isolated
landfill might at some future time cease to be active, or due to
possible mismanagement leaching could occur
2. Current incineration technology for PCB sludges do not
yield a zero emission exhaust and current Air Quality
standards coupled with cost make this alternative prohibitive
Although the new Toxic Substances Control Act stipulates
incineration as the proposed primary method of disposal some
persons believe encapsulation to be superior. The encapsulation
does not totally destroy the PCBs but it does, according to
preliminary test data, yield a less environmentally offensive
material. The method consists of powdering the sludge, mixing
it with various coagulating compounds and yielding when
power tamped, a strong, highly impermeable, clay-like material
suitable for landfills. Preliminary tests have been reported to
show low PCB leachability, with 48-hour aqueous extractions
yielding 4 to 5 ppb PCBs into the water." This approach and
others are being considered as alternatives in the search for a
simple, economical, and efficient means of PCB disposal.
Time does not permit a more detailed discussion on commun-
ity effects; however, the ramifications should be seen to be very
wide with respect to physical and monetary damages. The legal
questions of responsibility and compensation will be argued for
a long time—perhaps as long as one can expect the PCBs to
persist.
REFERENCES
1. Kuratsume, M., Yoshimura, T., Matsuzaka, J., and Yama-
guchi, A. Epidemiologic Study on Yusho, a Poisoning
Caused by Ingestion of Rice Oil Contaminated with a
Commercial Brand of Polychlorinated Biphyenyls,
Environ. Health Perspect., /: 119 (1972).
2. Allen, J. R., Carstens, L. A., and Barsotti, D. A. Residual
Effects of Short-Term, Low Level Exposure of Nonhuman
Primates to Polychlorinated Biphenyls, Toxicol. Appl.
Pharmacol., J0:44O (1974).
3. Jensen, S. The PCB Story, Ambio, 7:123 (1972).
4. Waldbott, G. L. Health Effects of Environmental Pollu-
tants, C. V. Mosby Company, Saint Louis, 1973, p. 228.
5. Stalling, D. L.,and Foster, L. M. Toxicities of PCBs to Fish
and Environmental Residues, Environ. Health Perspect.,
/: 159 (1972).
6. Camp, B. J., Hejtmancik, E., Armour, C.,and Lewis, D. H.
Acute Effects of Aroclor 1254 (PCB) on Ictalurus Puncta-
tus (Catfish), Bull. Environ. Contam. Toxicol., 12(2X204
(1974).
7. Nisbet, 1. C. T., and Sarofim, A. F. Rates and Routes of
Transport of PCBs in the Environment, Environ. Health
Perspect., /:21 (1972).
8. Furr, A. K., Lawrence, A. W., Tong, S. S. C., Grandolfo,
M. C., Hofstader, R. A„ Bache, C. A., Gutenmann, W. H.,
and Lisk, D. J. Multielement and Chlorinated Hydrocar-
bon Analysis of Municipal Sewage Sludges of American
Cities, Environ. Sci. Technol., /0(7):683 (1976).
-------
6 PCB Distribution
9. Hutzinger, O., Safe, S., and Zitko, V. The Chemistry of
PCBs, CRC Press, Cleveland, Ohio, 1974, p. 9.
10. Summary: PCB Committee Meeting, April 13, 1976.
Indiana State Board of Health, Indianapolis, Indiana.
11. IU Conversion Systems, Inc., University City Science
Center, Philadelphia, PA.
BIBLIOGRAPHY
Allen, J. R., Carstens, L. A., and Barsotti, D. A. Residual
Effects of Short-Term, Low Level Exposure of Nonhuman
Primates to Polychlorinated Biphenyls, Toxicol. Appl. Phar-
macol., 30:440 (1974).
Camp, B. J., Hejtmancik, E., Armour, C., and Lewis, D. H.
Acute Effects of Aroclor 1254 (PCB) on Ictalurus Punctatus
(Catfish), Bull. Environ. Contam. Toxicol., 72(2^:204(1974).
Furr, A. K., Lawrence, A. W., Tong, S. S. C., Grandolfo, M. C.,
Hofstader, R. A., Bache.C. A.,Gutenmann, W. H.,andLisk,
D. J. Multielement and Chlorinated Hydrocarbon Analysis
of Municipal Sewage Sludges of American Cities, Environ.
Sci. Technol., 10(7J:683 (1976).
Hutzinger, O., Safe, S., and Zitko, A. The Chemistry of PCBs
CRC Press, Cleveland, Ohio, 1974, p. 9.
IU Conversion Systems, Inc., University City Science Center
Philadelphia, PA.
Jensen, S. The PCB Story, Ambio, /: 123 (1972).
lCuratsume, M., Yoshimura, T., Matsuzaka, J., and Yamagu-
chi, A. Epidemiologic Study on Yusho, A Poisoning Caused
by Ingestion of Rice Oil Contaminated with a Commercial
Brand of Polychlorinated Biphenyls, Environ. Health Pers-
pect., 7:119 (1972).
Nisbet, I. C. T., and Sarofim, A. F. Rates and Routes of
Transport of PCBs in the Environment, Environ. Health
Perspect., 7:21 (1972).
Stalling, D. L., and Foster, L. M. Toxicities of PCBs to Fish and
Environmental Residues, Environ. Health Perspect., 7:159
(1972).
Summary: PCB Committee Meeting, April 13, 1976. Indiana
State Board of Health, Indianapolis, Indiana.
Waldbott,G. L. Health Effects of Environmental Pollutants, C.
V. Mosby Company, Saint Louis, 1973, p. 228.
-------
Safe Disposal of PCB's Myron W. Black
Amcord, Inc.
Detroit, Michigan
and
David Usher
Marine Pollution Control, Inc.
Detroit, Michigan
What Are PCB's?
The initials "PCB" stand for Poly Chlorinated Biphenyl, a
class organic compounds created by chlorinating the biphenyl
molecule. In practice this definition is expanded to cover
chlorinated biphenyls, terphenyls, and higher polyphenyls.
These chlorinated aromatics have many similar properties. In
addition, the term PCB is commonly used to indicate mixtures
of various chlorinated biphenyls and doesn't generally imply a
single pure isomer.
Frequently the PCB nomenclature is applied to materials
containing any appreciable content of PCB compounds. It's best
to recognize that the PCB expression is not scientifically precise
and further investigation may be needed to completely identify a
"PCB" material.
Typical characteristics of PCB's are:
Thermal stability
Chemical stability
Low vapor pressure
High dilectric constant and electrical resistivity
High density
Appearance ranges from clear oils to solid resins.
Why Dispose of PCB's
PCB's have been determined to have long term toxicity due to
bioaccumulation even when living matter isexposed to very low
concentrations. It's similar in environmental hazard to DDT.
The most noted PCB poisoning case is the Yusho incident in
Japan in 1968.1 Substantial quantities of PCB leaked into rice
oil that was consumed by Japanese families.
Effects of PCB poisoning include:
Chloracne
Increased skin pigmentation
Increased eye discharge
Visual disturbances
Feeling of weakness
Numbness
Headaches
Liver disturbances
As a result of increasing contamination of the Great Lakes,
many Mid-Western states have moved to place environmental
controls on PCB's. Typical is Michigan, which passed Act 60 in
1976 to "prohibit the manufacture, sale and use" of PCB's in an
attempt to control and eventually totally dispose of PCB's
without any additional environmental contamination. Rules
under the law have been promulgated. Michigan is currently
surveying industries to assess the extent of the problem. Soon all
PCB disposal will be under strict State control.
Later in 1976 the Federal Government moved to control
PCB's on a national basis with the Toxic Substances Control
Act passed on October 11,1976. Section 6e requires that by July
1, 1977 the Administration of the EPA will prescribe methods
for the disposal of PCB's and require proper marking. Starting
in 1978 the Act prohibits manufacture and regulates use of
PCB's.
Clearly, national policy has declared PCB to be undesirable
and we are rapidly moving towards control of its use and,
particularly, control of its disposal. A direct way of stating our
national goal is that we shall use and dispose of PCB's without
any further environmental contamination.
The problem is extensive as the following table shows:
PCB Use and Distribution in the U.S.2
(Period 1930-1975)
Million Pounds
Total Industrial Purchases of PCB 1253
PCB's currently in Service 758
PCB's in the Environment 440
PCB's Destroyed 55-
Industrial use of PCB's is broad and diverse.
Heat transfer medium
Carbonless copy paper
Hydraulics and Lubricants
Plasticizers
Capacitors
Transformers
Among these uses, large quantities of PCB's remain only in
capacitors and transformers. These PCB's will need proper
disposal as the capacitors and transformers are retired from ser-
vice. Considering the addition of solvents and dilutents, the
forseeable disposal volume for PCB's in the United States from
transformers and capacitors is over 1,000,000,000 pounds. This
amounts to greater than $100 million in costs, based on pub-
lished incineration costs.7 If we consider that other PCB
contaminated materials (Michigan rules require destruction of
materials over 100 PPM starting in 1978) will have to be
destroyed, the potential incineration requirement becomes even
greater.
Disposal Methods
The basic reference to disposal procedures was published in
the Federal Register of April 1, 1976. It outlines the two basic
disposal methods: Incineration and Land Disposal.
A debate is currently raging in the EPA as they struggle with
promulgation of specific methods for disposal. It can really be
called a dilemma.
Incineration is the ideal disposal method, but it has inherently
7
-------
8 Safe Disposal—PCB's
many practical operating problems that could cause immediate
release of PCB to the atmosphere and it is expensive.
Landfill does nothing to destroy the PCB's, but is inexpensive
and probably won't result in release of PCB's to the environ-
ment immediately.
Recent testimony3 by organizations such as the New Jersey
Department of Environmental Protection and the Florida
Power and Light Company has strongly supported the incinera-
tion route. Because it gets the job done permanently, incinera-
tion is strongly recommended.
There is little defense of landfill in the long term. Sooner or
later buried material will probably be released to the environ-
ment. An example is the current concern in Michigan over a
PBB contaminated dump. The toxic material is starting to show
in ground water. With the chemical stability of PCB, the best we
can hope for with landfill is that the environmental contamina-
tion doesn't happen in our generation. We are, in essence, not
solving an environmental problem, only delaying it.
The rest of this paper, therefore, will deal with proper
incineration of PCB's. It is expected that public policy will
support incineration wherever available and reliable. This is
currently the policy written into the rules of the State of
Michigan.
The Federal Register7 sets forth conditions for PCB destruc-
tion by incineration:
(1) Two second dwell time at 1100° C and 3% e xcess oxygen or
(2) One and one-half second dwell time at 1500°C and 2%
excess oxygen.
These conditions have been verified by actual experience as
we shall see later. And, of course, these are only two
combinations of a theoretically infinite number. If we apply the
usual laws of reaction kinetics, we can set one or two of the
conditions and design the third for comparable reaction
completion. The mechanism of actual thermal destruction for
PCB's will not be discussed.
However, engineers familiar with plant operations realize that
meeting theoretical conditions does not always make a success-
ful process. The practical man also asks about startup and
upsets and operator error. There is no question that any of these,
in the case of PCB, may create momentary PCB emissions if not
adequately controlled. This is the real heart of the incineration
vs. landfill controversy.
We are proposing a set of specifications for PCB incineration
against which any facility could be asked to measure itself:
1. The facility must be capable of meeting conditions
outlined in the April I, 1976 Federal Register or the
equivalent. (Usually excess 02 and residence time will be
firmly set in a design and temperature will be the variable
receiving the most attention.)
2. Auxiliary fuel burning capacity must be instantly availa-
ble.
3. Any facility certified for PCB destruction should be
required to operate at all times at conditions sufficient for
PCB destruction.
4. All flows of material for destruction should be accurately
recorded as a function of time.
5. Incineration operation tempeatures should be measured
and recorded as a function of time.
6. Draft fans should not be capable of reducing the residence
time below the required minimum.
7. Automatic shutdowns should be provided in case of low
temperature or low draft.
8. Adequate air pollution facilities must be operating to
prevent emissions of particulates and hydrochloric acid. A
caustic scrubbing system or equivalent is mandatory.
Any facility meeting the above specifications is as close as
humanly possible to faultless operation. It should be noted
though that it's also a difficult set of requirements to fulfill.
Use of Cement Kiln
Upon review of the conditions necessary for effective and
practical PCB incineration process, it has been observed that a
cement kiln, that is, a kiln used to make clinker for Portland
cement, meets the requirements very nicely.
The idea was first explored in a research study sponsored by
Environment Canada and the U.S. EPA at a Canadian cement
plant in 1975. The final report4 on this work was published
April, 1977 and was not available as a source for this paper.
The cement kiln fits the incineration requirements well for the
following reasons:
1. The cement process operates, by necessity, well above the
required temperature for PCB destruction. Normal oper-
ating temperature range to produce acceptable quality
clinker is 1370° to 1450°C.5 If temperatures drop below
1250°C horrible things happen to the cement process that
cannot be ignored. In considering also that PCB's can be
injected directly into the flame at an even higher tempera-
ture, it's clear that there is a large margin of safety on
temperature.
2. If we exclude preheater kilns (which present special
problems), the length of a cement kiln is ideal for residence
time due to the high ratio of length to diameter. Typicjj
length/diameter'1 ratio for long kilns run 20 to 25. The kiln
we'll describe later has a L / D ratio of over 30. The result is
a very long residence time in the hot zone of the kiln. We
have, typically, estimated a residence time of 10 seconds at
over 2000° F, well above the Federal guidelines.
3. Flow of material for destruction can be essentially inde-
pendent of the basic kiln process for a large cement kiln.
The kiln to be described has a heat load (coal fired) of 5oq
million Btu's per hour. Any reasonable flow of materials
for incineration can only be a small percentage of the heat
load. Furthermore, the flow of wastes for incineration can
be a constant. There is no need to vary flow rates with
temperatures or quality of materials- the main kiln
temperature control is adequate. This is in strong contrast
to a typical commercial incinerator operation which must
be constantly alert to the quality and flow rate of waste
material burned to keep temperatures controlled. Of
course, the larger the kiln, the greater the advantage.
4. Cement kilns are typically run at full capacity f0r
maximum efficiency. This capacity in many installations is
limited by the draft fan. In general, there is no opportunity
to pull a slug of undecomposed PCB through the kiln by a
sudden surge in gas flow. This factor, however, must be
evaluated for every installation.
5. The incineration process can be shut down at any time if
upset. And there is no need for a startup period where the
incinerator has to run below operating temperature.
6. The alkali and lime in the cement raw material act as
efficient scrubbers for HC1. It has been long established
that large quantities of chlorides can be added to the
cement process without HC1 emissions.
7. A cement kiln always has a "burner" or "operator" in
attendance when in operation. In modern plants he will
have the advantage of many alarms, recorders, and even a
process control computer. An auxiliary burning process
can be added without requiring additional manpower or
risking slow response to an operating problem.
PCB Burn Test—December, 1976
With the above advantages in mind, Amcord, Inc. carried out
a test burn of PCB's at its Peerless facility in Detroit jn
December, 1976 under carefully supervised conditions. PCfc
material was obtained from Detroit Edison Company as
Arochior 1260 drained directly from transformers. This mate-
rial was pumped at a rate up to .75 gallons/minute through a
-------
Safe Disposal—PCB's 9
specially designed auxiliary burner directly into the main coal
flame of the kiln. Simultaneously, the stack was sampled for
PCB emission testing.
The kiln used is a large modern wet process kiln—19'6"
diameter (large end) by 580 feet long. The kiln burns 20 tons of
coal per hour at a heat load of approximately 500 million
Btu's/hour. Feed rate of raw materials was 140 tons/' hour of a
typical limestone-clay raw mix. Emission control is provided by
electrostatic precipitator.
Test Results
Before I discuss our results, 1 would like to make a side
observation that tends to justify the whole effort to control
PCB's. The plant raw material (being wet process) contains
about 30% water. As a result, about 45 tons of water per hour are
evaporated in the process. This water comes from the Rouge
River in Detroit, a typical urban industrial river. It occurred to
us that we might find PCB's in our own process water and indeed
we did! As a result we were alerted to look for a background lev-
el of PCB's in our stack emissions. As predicted by recently pub-
lished studies," it was there. PCB is too thermally stable to be
completely destroyed by feeding in the cold end of a counter
current furnace such as a rotary kiln.
Table I shows the test results. All PCB rates are calculated in
micrograms/minute.
Tests #1 and #5 were the background tests (no PCB burned)
and showed the highest and lowest emission rates. It was
concluded that the emissions detected were all from the raw
material feed slurry and there was no evidence of any PCB
actually penetrating the length of the kiln. The shape of the
chromatograph scans backs up the conclusions that the PCB's
emitted were different than the PCB's burned. The variation in
the results is considered to be random error.
Waste Material Handling Facilities
In our investigation we held the opinion from the beginning
that the real challenge to PCB destruction in cement kilns is not
the process, but the practical problem of receiving and handling
waste materials at an existing operating cement plant. This type
of operation is quite foreign to normal cement activities.
We caution that this activity be controlled by expert special-
ists and that facilities be designed to eliminate every possible
route of environmental contamination.
The following specifications are recommended for a moden
toxic waste handling facility:
1. Isolated area, preferably well fenced and locked. Good
security from intruders and vandals.
2. All ground area within dikes of storage areas to be sealed
so that spills will not penetrate the ground. Sealed concrete
surfaces are recommended.
3. Well controlled drainage. All leaks, spills, rainwater, etc.
should be easily collected and saved for destruction.
Receiving area spills are particularly important.
4. All liquid storage in closed tanks, not open lagoons.
5. Methods to contain and recover piping leaks without en-
vironmental contamination.
6. Adequate alarms for abnormal conditions.
7. Leak-free design wherever possible.
It should be recognized that the above requirements can't be
met easily or cheaply. However, it would be unfortunate to have
a poor liquid handling facility tied to a super clean incineration
system. Both areas are equally important.
CONCLUSIONS
Disposal of PCB's by incineration is very desirable and
expected to be a well-defined national goal.
Recognizing that a critical need exists for facilities to do this
job right, the use of a cement kiln was tested for adequacy of
PCB destruction. The test results confirmed expectations. Clear
evidence exists that PCB's are destroyed.
The use of a cement kiln process poses advantages to other
incineration means that are hard to match. With adequate waste
Table 1: Calculated Data Table from Stack Testing Rotary Kiln—Peerless Cement Company, December 10-15, 1976, Detroit,
Michigan
Test Number
Assumed Total
PCB Emission *
Jig/min
PCB Injected
jig/min
PCB Stack Emission
as
% of PCB
Injected
Raw Feed
PCB Input
jig/min
PCB Stack Emission
SIS
% of PCB Raw
Ffeed Input
1
5,864
0.00
83,009
7.06
2
Sample invalid
—
...
3
7,703
566,100, 000
0.00137
59,816
12.98
4
33,212
1,698,300, 000
0.00195
71,826
46.24
5
44,030
0.00
-
83,364
53.90
* jjj/SCt x SCF x 2
nin
(Sample was spilt and results calculated from analysts of half of sample)
-------
10 Safe Disposal—PCB's
material receiving and handling facilities, it appears practical to
adapt a cement kiln to this foreign but very desirable auxiliary
use.
Our research was done, however, with the optimum cement
kiln facility:
Wet process for low gas velocity and cold back end tempera-
ture.
High production capacity for long burning zone and
minimum impact on the basic process.
Results should be verified with smaller and shorter kilns as
well as dry process kilns. In particular, there are reasons why we
"believe that the process won't work with a dry process preheater
kiln due to probable plugging from chlorides in the preheater.
REFERENCES
1. Final Report of the Subcommittee on Health Effects of
Polychlorinated Biphenyls and Polybrominated Biphenyl,
July 1976, Department of Health, EDucation and Welfare,
Wash., D.C.
2 PCB's in the United States, Industrial Use and Environmen-
tal Distribution, Versar, Inc., Feb. 25, 1976. NTIS PB-252-
012.
3 PCB's Public Hearing
'' Use 1 abeling and Disposal of Polychlorinated B\phenyls US
A Washington nr I— ^ ,
Wnt^r Prtlliitinn n •*~l rAl *-
Maryland 20014.
4. "Burning Waste Chlorinated Hydrocarbons in a Cem
Kiln". Technolnov IV vplnnmnnl
ient
, . —t — " r-7")
Water Pollution Control Directorate, Environment, Can-
ada, March 1977.
5 K.. E. Peray and J. J. Waddell, the Rotary Cement Kiln,
Chemical Publishing Co., Inc. (1972).
6 O 1 abahn & W. A. Kaminsky, Cement Engineer's Hand-
' book Bauverlag, GMBH, Wiesbaden, Germany.
7. PCB'Containing Wastes Disposal Procedure. Federal
Register, April 1, 1976, P. 14136.
« "Sludee Incineration". Environmental Science & Technol-
ogy Vol 10, No. 12, November 1976, P. 1081.
-------
Pros and Cons of
Waste Disposal Alternatives Alan MacGregor and Amir A. Metry
Weston Environmental
C onsultants-Designers
West Chester, Pennsylvania
INTRODUCTION
The treatment and disposal of residual wastes from industrial
operations is now receiving as much, if not more, attention than
the management of air and water discharges. The 1976 Federal
Law, the Resource Conservation and Recovery Act, establishes
a much stronger program for the control of all hazardous and
residual wastes. Numerous State programs are already being
implemented that have similar objectives as the Federal effort.
In planning management programs for waste disposal alter-
natives, it is necessary to consider all options that are applicable
to a particular waste. This paper summarizes waste management
technologies, outlines their applicability to general waste types,
and presents the Pros and Cons of each option.
Waste Management Technology
Depending upon composition, volume, economics, and other
important factors, proper waste disposal procedures will involve
one or more of the following acceptable methods:
1. Recycling of recoverable wastes or reuse for some safe and
useful purpose.
2. Removal of toxic or hazardous components by treatment
or by waste segregation prior to disposal.
3. Reduction of the volume of waste by segregation, evapora-
tion, or treatment of waste, or by process modification.
4. Conversion of toxic wastes to a non-hazardous form by
chemical, thermal, biological, or other methods.
5. Burial of highly toxic wastes (e.g., radioactive waste) in
licensed, specially designed hazardous waste disposal sites.
6. Burial of innocuous or detoxified wastes in sanitary
landfills under special precautions.
All but the last of these methods could be undertaken at
licensed disposal sites. Similarly, waste producers could provide
for treatment and recovery in some cases, and for storage in
nearly all cases, as part of the overall management of hazardous
waste.
The objectives of hazardous waste treatment are the destruc-
tion or recovery for reuse of hazardous substances and/ or the
conversion of these substances to innocuous forms that are
acceptable for uncontrolled disposal. Several unit processes
may be required for the treatment of a given waste. In some
cases, hazardous residues that cannot be destroyed, reused, or
converted to innocuous form result from treatment. These
residues will then require controlled storage or disposal.
Treatment technology can be grouped into the following
categories: physical, chemical, biological, or thermal.
At-Source Controls
The main strategy should be to concentrate hazardous waste
at the source rather than to dilute them into the environment. Its
concentration minimizes handling and transportation prob-
lems, makes resource recovery from these wastes economically
more attractive, and allows better management control.
Concentration at the source can normally be accomplished by
physical treatment, chemical treatment, a combination of both
physical and chemical treatment, and segregation of materials.
Physical Treatment Processes
Reverse Osmosis: Reverse osmosis is the physical transport of
a solvent across a membrane boundary, where external pressure
is applied to the side of less solvent concentration so that the
solvent will flow in the opposite direction. This procedure allows
solvent to be extracted from a solution so that the solution is
concentrated and the extracted solvent is relatively pure.
Dialysis: Dialysis is a process by which various substances in
solution having widely different molecular weights are sepa-
rated by solute diffusion through semipermeable membranes.
The driving force is the difference in chemical activity of the
transferred species on the two sides of the membrane. Dialysis is
particularly applicable when concentrations are high and
dialysis coefficients are disparate.
Activated Carbon: Activated carbon adsorbs a great variety
of dissolved organic materials including many which are
nonbiodegradable. Adsorption is facilitated by the large surface
areas on the carbon granules which are attributable to its highly
porous structure. The carbon in certain configurations can also
function as a filter.
Gravitational Separation: Gravitational separation by sedi-
mentation is generally an effective technique for removal of
unstable and destabilized suspended solids from waters and
wastes. Chemical conditioners are commonly employed with
sedimentation techniques to enhance the separation process
when fine particles are difficult to separate from the medium in
which they are suspended.
Flotation: Flotation is a unit operation used to separate solid
or liquid particles from a liquid phase. Separation is brought
about by introducing fine gas (usually air) bubbles into the
liquid phase; the bubbles attach to or form on the particulate
matter, and the buoyant force of the combined particle and gas
bubbles is great enough to cause the particle to rise to the
surface.
Filtration: Filtration or dewatering constitutes the physical
removal of the solid materials from the aqueous waste streams
by means of a filter medium. An ideal dewatering operation
would capture practically all the solids in the dewatered cake af
minimum cost. The resultant cake would have the physical
handling characteristics and moisture content optimal for
subsequent processing.
11
-------
12 F'ros and Cons
Chemical Treatment Processes
Ion Exchange: Ion exchange is a unit process by which ions of
a given species are displaced from an insoluble exchange
material by ions of a different species in solution. Ion exchange
operations may be either batch or continuous. Ion exchange
technology has been available for many years and has been
employed for removing traces of metals and cyanides from
various waste streams.
Chemical Precipitation: Chemical precipitation involves the
addition of chemicals for the expressed purpose of removing
specific soluble components contained in wastewater. The
addition of precipitating chemicals under proper conditions
causes the formation of a settleable precipitate containing waste
materials which can be removed by conventional sedimentation
or flotation processes, as previously described.
Neutralization: Neutralization implies the adjustment of pH
to values at our near neutral pH (pH 7.0). These processes may
be operated as batch or continuous processes.
Chemical Oxidation / Reduction. Chemical oxidation is a
process in which the oxidation state of a substance is increased.
Conversely, chemical reduction is a process in which the
oxidation state is reduced. The purpose of oxidation/ reduction
is one of converting undesirable chemical species to species
which are neither harmful nor otherwise objectionable.
Chemical Fixation: Chemical fixation of industrial materials
has been developed by several companies. In all fixation
systems, proprietary chemicals are mixed with the waste
sludges, and the resulting mixture is pumped onto the land,
where solidification occurs between a few days and a few weeks
(depending upon the process).
Biological Treatment Processes
The applicability of biologically treating a particular waste is
a function of the biological degradability of the dissolved
organics present in the wastewater. When considering the eco-
nomics of a biological treatment system, the time required to
biologically degrade the dissolved organics is of primary impor-
tance.
In general, a biological system is an economically viable an-
swer to organic destruction only when the waste stream is large,
continuous, and fair-y constant in its composition. Normally,
physical, chemical or some combination of physical-chemical
treatment processes will be selected for hazardous waste
treatment in preference to biological treatment processes if the
above conditions are not met.
Thermal Processing Techniques
The selection of thermal processing as a means of treatment or
disposal of waste is a function of the environmental adequacy of
the process as compared to other means of disposal and of the
relative economics of alternate disposal methods. The thermal
processing techniques which may be applicable are as follows:
Evaporation: Evaporation is the removal of volatile materials
(e.g., solvents) from a waste stream (sludge, slurry or residue).
As a unit process, this is normally accomplished by bringing the
volatile material to its boiling point to effect rapid vaporization
by applying heat energy. The vapor may or may not be
recovered depending on its value and/ or impact on air quality.
Incineration: Almost 60 percent of the hazardous wastes
generated in the United States are organics, and can be
destroyed or detoxified by incineration. Emission control
facilities are usually required for hazardous waste incineration,
and are considered an integral part of the facility. Control
devices are normally adaptable to flue gas streams from an
incinerator to reduce sulfur oxides, nitrogen oxides, particu-
lates, and hazardous breakdown products. When scrubbers are
used for emission control, neutralization and proper disposal of
scrubber solution is necessary. Dust from electrostatic
precipitators, baghouses, and other mechanical devices must
also be handled and disposed of in an environmentally accept-
able manner.
Other Thermal Processes:
• M olten salt has long been used in the metallurgical industry
to recover metals (especially aluminum).
• Wet oxidation (Zimmerman Process) is a physical/ chemi-
cal treatment process capable of breaking down organic
materials via flameless oxidation.
• Plasma destruction is an experimental process that consists
of applying microwave energy to excite the molecules of the
carrier gas, thus raising electron energy levels and forming
very reactive free radicals.
• Pyrolysis is the thermal decomposition of organic material
into solid, liquid, and gaseous constituents. A major
attraction of pyrolysis is the potential for recovery of eco-
nomic value from waste products.
Ultimate Waste Disposal
Ultimate disposal of waste is practiced by discharging such
waste in one of the following sinks: land by filling, land
application, deep-well injection; air by incineration and evapo-
ration; water by ocean disposal or discharging into surface and
subsurface waters.
Landfills that are located, designed, constructed, operated
and closed in a manner that makes them suitable for disposal of
hazardous wastes are called special, secured, controlled or
chemical landfills. Figure 1 illustrates the various ingredients
that make such a class of landfills safe for disposal of hazardous
wastes; these include:
1. Locating the site in a manner that provides good access,
adequate separation to residential and commercial devel-
opment and to major ground and surface water supplies>
and good visual screening. The site should also be located
in an area which has suitable earth materials to support the
landfill and its related structures, provide means for
leachate attenuation, and provide material for interme-
diate and final cover.
2. The landfill is designed in a manner that contains the waste
and prevents leachate migration into groundwater. In
most instances, a liner will be required for containment
and collection of leachate. Common types of liner mate-
rials include clay, rubber, asphalt, concrete, and plastics.
Leachate collection process usually requires sand, pipes,
and pumps. Leachate treatment includes physical/ chemi-
cal, biological, recirculation, etc.
3. The land disposal facility should include means fQr
hazardous waste storage and treatment (neutralization,
detoxification, encapsulation, etc.). Other support faciljl
ties include employee facilities, fine lighting, first aid
communication, etc.
4. Landfilling must be carried out in a manner that protects
the operators, the environment, and the public. Placement
of waste should be conducted under tight supervision,
utilizing special equipment in order to minimize explosion
and toxicity hazards. Incompatible wastes (such as ammo-
nia and acid wastes) should be segregated and disposed of
in separate sections of the landfill.
5. Closing of a special landfill should include proper cover-
ing, vegetation, labeling of different areas, documenting
the location, etc.
Generally, land application is suitable for ultimate disposal of
wastes that consist primarily of biodegradable materials,
H owever, site design and application rates should be limited in a
manner that prevents accumulation of hazardous substances in
soil and water resources or in the human food chain.
-------
Pros and Cons 13
FENCING AND SITE ISOLATION
ADtOUATE SEPARATION TO RESIDENTIAL AND COMMERCIAL
DEVELOPMENTS
STORAGE AND PFSETREATMENT OF HAZARDOUS WASTE
VISUAL SCREENING
EMPLOYEE rACItlTies. FIRST AID COMMUNICATIONS, FIHE FIGHTIIs'G,
/N. MAINTENANCE. ETC.
FINAL COVER
LEACHATt COLLECTION
AND TREATMENT
SUITABLE EARTH MATERIAL
ADEQUATE SEPARATION TO GROUND WATER TABL E
GROUND WATEP
Figure I: Elements of Controlled Landfills
Wastes containing excessive amounts of inorganic salts,
heavy metals, pathogenic organisms, toxic explosive materials,
etc. are not amenable to disposal by land application and should
be disposed of by other means.
Resource Recovery
Recovery and recycle of waste where possible should be con-
sidered as a major alternative to treatment and disposal.
Hazardous waste should be concentrated at the source where
possible whether the waste is to be treated and disposed of or
recovered and sold or recycled back into the process. One
method would be to reduce the amount generated by process
modifications and/ or changes in the raw materials. Hazardous
waste may also be concentrated at the source to minimize
handling, transportation, treatment, and disposal problems.
For example, recovered acid, alkaline or solvent wastes can be
sold as a product or recycled back into the process. Recovery
and recycle of metals, energy content, and other useful re-
sources contained in hazardous waste should also be consid-
ered.
Many hazardous wastes contain valuable basic materials,
some of which are in short supply. Material recovery makes
sense from both resource conservation and environmental
points of view. Extraction of materials from concentrated
wastes generally requires less energy and generates less air and
water pollution than the mining and processing operations
required to produce the material from virgin resources. As
material shortages become more widespread, material recovery
from hazardous waste will become more economically attrac-
tive.
Applicability of Treatment Technologies
to Selected Waste Streams
For wastes that are generally recognized as potentially
hazardous, most waste management technologies are inade-
quate in terms of providing sufficient health and environmental
protection. Biological treatment (and associated clarification),
for example, is not useful to treat toxic, flammable, or other
types of hazardous wastes. Sludges from industrial waste
treatment processes often contain high levels of heavy metals;
such metal content precludes land appJication or sanitary
landfill of those wastes. In fact, sanitary landfills offer inade-
quate protection for disposal of all but the most innocuous
industrial wastes.
Table 1 provides a listing of generalized waste streams that
could be considered potentially hazardous, if not treated and
disposed of adequately. The options listed for each waste stream
are those technologies that provide adequate protection.
Although most of these processes/techniques are in use by at
least one facility, a few are presently in the "pilot" or "bench-
scale" stages of development.
The waste streams listed are generalized "generic" waste terms
based on recent research and industrial profiles performed by
various contractors for EPA. The listing was prepared as a
portion of a hazardous waste management study for the State of
New Jersey.
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14 Pros and Cons
Table I: Generalized Treatment and Disposal Options
W..^tc:wnt,
• f.hi:m i Cd I I i x j t i on , •>
l.-Cy < I .. (if pos - ' l> I ) •
11¦ i Lir'(¦ lundf ill.
¦i; Icindt i I
iry l.jndl i
jlvcnl re cov.-ry
ulv<.-nt'. and •> 1 udcjr'
Oil 1'L'fiiu-ry production w.
L--.id''0 ijd'io 1 i fit tank si ml'
Non - I H.idi'd I.ink -Jud^i-.
Crude ui I tank s ) ud<|f .
Inert •> -cuh t iirnin.iled was te
• Si-cur,- land! i 1 I .
• S veil re I and I i I I .
• S-'Cur. I jnd till.
. E v.ipor., t i on , ^un- l.n.lfMI.
•i: lurldf I
r..j I trt-a
• Secure.- I arulf ill.
• Ground I i ft'j.
Chemical treatment., secure
S t oraye.
M.-t.|l v.,1 -. I i: 'j (dry) .
Oil jnd heavy octal 'jludqeb.
Dye, chur:. i c.i I , and pesticide containers
H'H'i.-nt. cha'iicji am! pesticide bjys and
iurr'i water silt from htijvy industrial
Secure Kmdt i
Ground iea I i n
§ Recovery.
• Secure lai
• Oi I recovery , secure i
• Rinse, sanitary landti
Incineration, «ish to secure
landfi 11.
Secure landfi
Pros and Cons of Waste Disposal Alternatives
Although Table 1 lists only one or two options for each waste
stream, these are technologies applicable to potentially hazard-
ous waste streams. Most industrial waste streams, although
requiring treatment, do not need to be subjected to the high
technology levels of treatment listed on Table 1 if they are not
hazardous. Therefore, since there is no"one" option available to
the waste generator, he must evaluate all applicable technologies
to be sure that an economic solution is selected. Of primary
interest for consideration are any advantages or benefits that
can be achieved through in-process modifications, at-source
separation and treatment of wastes, and resource recovery
measures.
Table 2 offers a brief listing of the advantages and drawbacks
to the more general options discussed earlier. Criteria consid-
ered were relative cost, ease of operation, potential for
pollution, long-term liability, land requirements, and accepta-
bility to the public and to regulatory agencies.
Conventional landfills are cheap and available means of
disposal. However, few industrial wastes can be safely disposed
of in this manner. There is also strong public opposition to most
new sanitary landfills. Chemical landfills are naturally more
expensive, but have the same operational advantages as conven-
tional landfills. However, most wastes require dewatering and
usually some other "pretreatment". Liquids and flammable
materials cannot be placed in a secure landfill.
Incineration operations are generally expensive to construct
and operate. Although some wastes require additional fuel to be
completely treated, others offer potential for energy recovery.
Other forms of waste treatment are usually a part of most
industries' residual management system: physical, chemical,
biological. Most produce significant solids which must be
disposed of safely.
Land application, like landfilling, is only suitable for certain
wastes, and is dependent on sufficient suitable land area. High
land costs may make this option less attractive. Deep well
injection is a form of final disposal that is highly dependent on
geology to be feasible. 1'he potential for major environmental
damage exists and this option is usually discouraged by regu-
latory agencies. Ocean disposal is no longer an option to be con-
sidered, with the phasing out of ocean dumping permits.
Table II: Characteristics of Waste Disposal Alternatives
•""> « t j 0n
• -'"op,
• 'ti |i> •- in-1.,.- [>roduc l
'"•'¦¦l ii I i i "taj is,
;
"'ds
dln'°nt p,0_
<•>)..is
Land Appl i
(ef f I lion t4
• "if.ri
Kesource Recovery
(H.i 11: i" i n) ^ou rt.
CONCLUSION
Even though the available options for a specific hazardous
waste may be limited to one or two techniques that woum
provide complete protection to man and the environment, mQ .
industrial wastes are amenable to treatment by several tech-
niques. All wastes should be investigated for the feasibility (and
economic advantages) of in-process, at-source controls anrf
modifications that will reduce the quantity and hazards,
source recovery, both for energy and materials, should be eval-
uated for both short and long term attractiveness.
-------
Michael Crafton and
Practical Problems in
the Operation of a
Hazardous Waste
Disposal Site
Edward Kleppinger
Industrial Liquid Waste Disposal
Company
Indianapolis, Indiana
INTRODUCTION
1LWD as a company exists simply and solely as the result of
environmental controls which have been increasingly placed
upon industry over the last ten years. Jt exists to help answer the
question—"okay, now you have made us take it out of the air
and the water, what do we do with it?" There is a need, we
believe, for private industry to provide an environmentally and
economically sound means of treating and disposing of these
"hazardous" wastes. Recognizing, of course, that anything out
of place can be hazardous.
Many business analysts engaged in a new business study for
the typical American corporation might analyze the industry as
one which should be aggressively exploited and very profitable,
such has not been the case. Why not? After all, if the laws
presently on the books are even partially enforced, will not a
bast amount of material be "created" for disposal? Someone has
to treat and dispose of the material and it should be more eco-
nomical for a central location to do the job. Access to
technology, waste synergy and economics of scale should
provide a significant economic advantage. For example, we deal
with about one hundred customers, some two hundred sites. For
each of the two hundred sites to build a smaller version of the
necessary pieces of our process has to be very much more
expensive than the freight costs to a relatively nearby central
location. From time to time, we are able to blend different waste
streams to treat them, an economic advantage denied the captive
facility.
Even if the waste is not moved to a central location, a
company which has waste treatment as its only business
typically can treat or pretreat waste at the customer's site much
more economically than he can. In a recent case, our price for
operating a customer's pre-treatment facility was 25% less than
his cost and we guaranteed better performance.
As an additional point, the economics of a central waste
treatment company extend to the regulatory agencies. It is much
easier for them to provide rigorous control over an ILWD than
to do it at two hundred sites.
The industry, despite the above economic and environmental
arguments appears to us to be weak, small and highly frag-
mented. An industry populated by the landfill operator and the
midnight dumper. An industry in which even those who have
been well financed, well marketed, and well backed technically
have repeatedly run afoul of the law.
We propose to examine some of the practical problems
ILWD has faced during its history. We think if we are atall rep-
resentative, they will begin to explain why the industrial waste
treatment and disposal business is not one to enter lightly and
will not be very profitable for some time.
Background
ILWD currently operates a sophisticated industrial liquid
waste disposal plant which handles approximately 100,000
gallons per day of assorted hazardous wastes. While these
materials are classified as hazardous wastes, ILWD basically
handles materials on the lower end of this spectrum, i.e.,cutting
oils, coolents, acids, alkalies, petroleum solvents, wastewater
treatment plant sludges, and plating wastes. These materials are
handled through a series of processes which reduce the incoming
waste to a salable oil, water and solids. The oil fromourcurrent
system is sold in the commercial oil market, the water is
discharged to what is at times a dry stream and the solids are
sealed in clay at our onsite industrial waste disposal site
(landfill).
The first step in this processing is the removal of oil from the
water phase. This is accomplished through gravity separation,
heating, screening and high speed centrifugal separation. This
material is then ready to market as an ASTM grade # 4 fuel oil.
The water and solids phases of the incoming industrial wastes go
through a primary equilization tank and than to chemical
treatment. The chemical treatment step is used to remove
residual heavy oil and metals which would endanger both
biological activity within the biological treatment plant and
stream quality upon discharge. The oil is acid cracked. The
heavy metals are removed in chemical treatment by precipita-
tion using lime addition and several polishing agents. The water
portion, after chemical treatment, goes to the biological treat-
ment area.
The sludge generated during chemical treatment is pumped to
a 30,000 gallon sludge storage tank and then to a large plate and
frame filter press. The solids which come off the filter press are
dropped on a series of conveyors and loaded into dump trucks
which take this material to our onsite industrial waste disposal
site (landfill). The water which is removed from the sludge by the
filter press goes to the biological treatment area.
The biological treatment area consists of a 75,000 gallon sec-
ondary equilization tank (primary to the bio system), 40,000
cubic foot roughing filter, 250,000 gallon activated sludge basin,
sixteen feet diameter overflow clarifier with sludge return and a
4,000,000 gallon extended aeration pond. The input to the
biological system is through the secondary equilization tank,
where the wastewater at this point containing only organics and
having a high pH is fed into the recirculation line to the roughing
filter. The roughing filter has a recirculation rate of 1,500 gallons
per minute. This water is pulled from the activated sludge basin,
sprayed over the roughing filter and then returned to the basin.
The wastewater then travels through the activated sludge basin
into the clarifier. The clarifier overflow then goes to the
15
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16 Practical Problems
extended aeration pond from which it is discharged to the
stream.
The .system is the result of four years of continual upgrading
to keep the plant abreast of current technology and environ-
mental regulations and customers' needs. Additions to the
system are presently in design stage.
When ILWD first started some ten years ago, simple oil-
/ water separation was the only process. The oil off this process
was low grade and used for road oiling or blended with other
fuels and burned. The water just somehow disappeared. As the
business continued it was seen that it would have to be upgraded
to meet existing and then future environmental standards or
abandoned. At this point, the department head of the School of
Environmental Engineering of a local university was retained as
a consultant. He, working in conjunction with several faculty
members developed the existing basic plant design which was
constructed in early 1973.
The plant was in full operation by mid-1973 and at this point
several major problems were discovered.
T he chemical treatment system developed a severe corrosion
problem in pumping the industrial waste. Due to the complex
nature of the material many pump manufacturers were hesitant
to recommend pumps for this area and many more were sorry
that they did! While in theory lime preciptition of copper
hydroxides and nickel hydroxides will bring you well within
acceptable discharge limits, we could not obtain this at our
plant. Therefore, additional chemicals were added to reduce the
amount of copper in the chemically treated effluent.
The original plant design for handling hydroxyl sludges pro-
duced in chemical treatment was a series of sludge drying beds.
These beds were built with an underdrain system and a sand
bottom. While these beds worked very well during low rainfall
periods theydidnotadapt well to year round use. This problem
was partially corrected by converting the drying beds to
thickeners and sending the thickened sludge to a large rotary
dryer. The sludge dryer was operated on an experimental basis
for approximately one year and then discontinued. The imme-
diate basis for discontinuing use of the dryer was primarily a
correctable particulate problem. The it was not cost effective to
operate and we expected EPA to start limiting heavy metal
emission at some future date and thus we chose to abandon the
dryer. The rotary dryer was replaced with our current means of
sludge dewatering, a plate and frame filter press.
The biological system originally designed for this plant was a
250,000 gallon activated sludge basin using a sixteen foot
diameter overflow weir clarifier for BOD removal and a one and
a half acre clay filter for final polishing of BOD and trace metals.
Upon start-up the system was seeded with domestic sewage
sludge and good reductions in BOD were produced. The clay
filter did produce an effluent crystal clear in color and showing
only detectable levels of heavy metals. After two weeks in
operation the percolation rate on the clay filter had been
reduced to four gallons/acre/hour. The filter was abandoned.
After start up, the activated sludge system gradually went
down hill. Cell synthesis within the system was nil. At first it was
felt that the system might be deficient in nitrogen, but it was later
determined to be in excess of the biological requirements due to
the organic nitrogen concentration and nitrates in the incoming
waste. A vast amount of work was done to determine first if
something within the system was causing a toxic effect and if not
what was limiting the biological growth. It was determined that
the probable problem was with a nutrient deficiency and not
toxicity.
The biological system had to be added to include a 40,000
cubic foot roughing filter, which has the capacity to handle 4,000
pounds of BOD per day, and a 4,000,000 extended aeration
basin. The total biological system has the capacity to handle
8,000 pounds per day of BOD with a hydraulic residence time of
some one hundred days under typical operating conditions
These later additions were made necessary by the low biological
growth rate we experienced for corresponding BOD reductions
and by the continual changing nature of our customers' waste
Problems
Biological Treatment
Perhaps the most severe problem we face is in operating a
biological treatment plant which if you consider the organic
loading acros the facility must constantly meet 99.99+% removal
efficiencies for discharges into what is at times a dry stream. This
winter our bio system operated at 0° Celsius for extended
periods of time. Trickling filters do not work too well in 30 mile
per hour winds and minus 30° farenheit weather. We are
presently working on a fix for this problem. It is, however, only
the latest of a series of problems a series which we feel is close
to conclusion.
We do a very high degree of chemical treatment ahead of the
bio system. This eliminates toxic metals but adds back high lev-
els of TDS, particularly sulfate and calcium. There is after all no
such thing as a free lunch. We found early on that we had done
too good a job of removal in some cases and now must add some
metallic nutrients after chemical treatment. The high calciu^
levels cause significant amounts of scaling in the system—ever
try to clean out a thousand or so feet of two inch pipe under tons
of rock? The corrosion problem is severe. The aluminium skirts
on the clarifier didn't last very long. Floating aerators are not
designed for operation in sea water. Our poor bugs have to worlj
against severe osmotic pressures.
We have this excellent clay on site with high ion exchange
capacity. The answer to our prayers, we thought. A tertiary clav
filter was constructed. It worked very well for about a week, ^
best we can determine the high TDS causes intense and
immediate swelling. On the other hand the clay does allow for
one of the best possible land disposal of residuals operation
around since the clay will ion exchange and seal. Onsite lagoons
are easily and totally sealed from ground water. There is
landfill leachate if only dried material is sealed in the clay.
We have had problems with nickel in addition to copper
should be essentially removed with the rest of the soluble heavv
metal hydroxides and sulfides during chemical treatment
Studies have led us to believe that the nickel forms a stable
organic complex which is attacked by our bugs as a last resort
Thus, we feel that nickel will reach acceptable levels at low BOli
levels.
A problem we have had with the bio system in particular and
the entire operation in general is that everyone tries to relate us
to something they learned or saw in a textbook. Not so, the
processes as we operate them are not discussed and
recognized as feasible. For example,everyone wants todo SVr8
and operate by them. We find they are meaningless in our
operation. Our MLVSS rarely runs more than 50% and we are
happy to average 45%. Textbooks have a problem dealing with
this.
Equipment
Equipment suppliers should beware of over optimism jn
dealing with industrial waste companies. We have sent several
home in tears. We are particularly fond of the salesman wh
guaranteed the performance of his pump in our service f0°
ninety days. We returned it to him three days later in five or si*
major pieces and numerous minor ones.
Our filter press has given good service but we are on our third
redesign of the plates. The press was going to be very clean and
neat to operate. Indeed, we even took advantage of the building
we constructed to house the press to install a storage area f0
tools and supplies. Wrong again! Plates and gaskets blow reguF
-------
Practical Problems 17
larly. Small changes upstream— some of them untraceable cause
plates to blind -creating problems in clean operation.
One of our present problems is finding a liner for our
centrifuge which will last more than 15,000 gallons. Hard
chrome and WC went faster than the plain stainless.
We think the secret to the business is not necessarily the
technology you choose to use. The key is conquering the very
steep learning curve, in adapting it and learning how to use it in
the face of very severe and constantly variable service.
The Public
The problems in operating a facility like ILWD are not only
technical. Given the public climate of mistrust of social institu-
tions in general and industry in specific, the operation of an
industrial waste disposal site without public reaction is an
impossible dream. In our area PCB's have been a problem. We
do not handle them but our public is still suspicious. Further,
daily newspaper accounts of Kepone, PCB's, contaminated
penta, and the shut down of the Louisville treatment plant
arouse suspicions about our operations.
The first thing we have had to do is to eliminate any grounds
for concern. In our early days we had several fires, 1 suspect that
five years from now we will still have our neighbors expressing
concern over fire at ILWD. Assuming one can operate a waste
treatment and disposal plant without ever giving actual insult to
the neighborhood, and we do, the next step has to be to
eliminate apparent problems. For example, in discussing our
problems and their solutions with a number of our neighbors,
we became aware that trucks delivering at night caused great
concern, "if it comes in the dark of the night it must be bad". We
also got accused of taking garbage in our disposal site after we
had the local garbage hauler start taking out our plant trash.
Landscaping and planting fish in one of our ponds we feel will
help our public relations problem.
The public, or ours at least, is very sophisticated. They
appreciate the need for our type of facility if their larger
concerns for a cleaner environment are to be realized. We are
still struggling with the problem of providing them the needed
and required answers that we are part of the solution, not part of
the environmental problem. We find it difficult to assure them
that we are one of the best when they have seen no others and do
not have faith in government controls or technical expertise to
monitor us. We have, for example, agreed to pay the cost of an
independent testing laboratory to analyze stream samples
obtained by a downstream neighbor. He simply pulls stream
samples on a random basis when he feels like it and sends them
directly to the lab. Results are sent only to him. The only thing
we get is the bill. We held an open house last fall and will do so
again. At the next one we may even serve the steer, if we have any
left, we are buying from a local farmer who had concerns that it
was contaminated from drinking from the stream. We have
repeatedly said we have an open door—come see us. A number
of neighbors have, some bringing their children.
NPDES
We have had a number of problems with our NPDES permit.
Problems which we hope our proposed bio treatment modifica-
tions will make a thing of the past.
With respect to metals, except for nickel, we have never had
any problems. We have completely avoided acute and bio
accumulative toxicity problems e.g. PCBs and Hg by not
processing them in the plant.
In dealing with a dry stream we have gone to an extended
aeration/holding lagoon with a one hundred day storage
capacity. We have been able to meet the stream quality limiting
values of our permit since its construction. No, it isn't presently
full! By the way, we monitor some twenty-seven parameters
including W for which there is no standard method and some
metals at levels whichareat the detection limit. We don't know if
this is one of the longest permits around, but it must be near the
top. As an additional safeguard we have an approximately three
million gallon holding/settling lagoon holding water pumped
from a nearby quarry. This is discharged when we are discharg-
ing from the extended aeration basin so as to blend before
entering the stream.
With respect to those parameters which are supposed to rep-
resent best technology levels, we have been less than successful,
primarily in the area of organic loading. Textbook numbers, lab
studies, and engineering calculations upon which we have based
expected concentration numbers seem to fall short. This is
probably due to several factors. Our incoming waste is variable.
When you are dealing with a 10,000 ppm inlet BOD to the bio
system a small change in removal efficiency—say 1% represents
a large number. To our knowledge, no other plant of this type
has been successfully built and operated. Thus no numbers are
available for comparison.
Inventory
This business has a strange phenomena associated with it. We
call it the "negative inventory"effect on the P&L. Unfortunately
the accounting does not reflect it. Simply stated, it is very easy in
this business to hype profits by simply taking in waste and not
treating it. No costs are associated with the sale if the waste is
stored, not treated. We have been successful in reducing our raw
waste holding area by at least 50% over the last two years.
The problem is to learn how to say no when by running a new
dike you can bring in another $50,000 or so in sales. Some
companies in the business do not resist. Thus one finds the "buy
the old bulk plant" or "lease the large warehouse" syndrome.
For example, we understand that a large warehouse in Pontiac is
presently being emptied at the expense of the waste generator
after the waste company went bankrupt. An Indiana company
having acquired an old bulk plant, has been accepting waste
before having the ability to dispose of it properly. We under-
stand it is to be closed. Will there be enough assets to dispose of
the "negative inventory"?
On the other hand, we have a problem in that some of our
legitimate customers need lagoon clean outs which may involve
moving 500,000 gallons to our site in three days. We must have
the storage capacity to handle this.
Customers
Our customers seem to fall into two categories. Those who
accept responsibility for the proper disposal of their waste and
those who are forced to do it. In the latter category, including in
our recent experience a Federal agency, we routinely find the
"we don't have any waste company". After two years of stopping
by and getting the above answer we get a phone call—generally
after nine PM on a weekend. The plant has "discovered" a
100,000 gallon lagoon behind the plant which is about to run
over. Trucks need to be sent yesterday.
Barrels are another problem. We follow a policy of sampling
each load of waste. It gets very difficult in the case of barrels. We
have to bulk up each customers' load and then check. We try, in
so far as possible, to get each customer to bulk his material. It is
a lot less expensive for him and we don't get hurry up calls to
clean out a large number of unknown barrels. We do not, by the
way, respond positively to these calls.
One thing that works in our favor is that our responsible
customers recognize that the waste is their responsibility even
after it gets to our site. We encourage them to check up on us reg-
ularly. We obtain a sample from each customer before giving a
quote. The customer certifies to us that the material he sends us
is representative of the waste and he will notify us if it changes.
-------
18 Practical Problems
We reserve the right to return the waste load to the customer at
his expense if it doesn't meet the parameters of the sample.
The problem in our business is learning how and when to say
"no". If you don't you may not be able to say it.
SUMMARY
It has been said that every problem is an opportunity. From
our view, the industrial waste business at times has represented
overwhelming opportunities. Our feeling is that there has to be a
business in the field. Someone has to do the job of treating
residues. We hope that we will be able to climb the learning
curve and solve the practical operating problems that seem to
keep theory from becoming reality.
-------
Effluent Disposal
in a Surface Pond
Lined with Spent Charcoal &
Diatomacious Earth from
Beeswax Bleaching Plant
Irving Deutsch
and
Douglas G. Fronmuller
Deutsch Engineering & Testing Services
East Meadow, New York
INTRODUCTION
In New York a permit is required to introduce untreated
liquid industrial wastes into ground waters. Our firm was
retained to survey the effluent waste and ground watercondition
and recommend a suitable treatment program, if required, for
the residue of manganese dioxide and potassium hydroxide
from the beeswax bleaching process at two major wax process-
ing plants. Phosphoric acid is used to neutralize the potassium
hydroxide and to prevent emulsification of the wax. Clay
activated carbon and diatomacious earth are used to absorb the
oxidized coloring compounds. Wax entrapped in the filter cake
is recycled after extraction with recycled tousol. The process
used to treat the residual wastewater, for some thirty years, was
to drain the waste residue into a lagoon. The survey showed lush
growth around the drainage areas, and the history indicated that
the land had been farmed or used as a garden area for years,
without any harmful effect to the people eating the produce
from the gardens, or to the surrounding trees and other
vegetation.
The waste filter cake formed a natural, almost perfect filter, as
indicated by digging into the lining. Pure uncolored sand was
found with no mixed boundary layer. In the past this filter was
hauled away periodically as it became thicker, but now it is used
to simply improve the lagoon filtering system. Analyses of the
water at the water table and approximately ten feet below the
water table indicated that the ground water was not affected as
shown in the analyses of key components shown below:
iest For:
23 Ft
mg/1
y.6
1-k
6.5 to ti.fj
Manganese
0.1+1
O.eb
O.to
Chlorides
10
Ik
i>00
Total Dissolved
154
ill
1000
Solids
Nutritional research conducted at Ohio State U. by Dr. Elton
M. Smith indicated that in certain soil regions, especially
alkaline areas, the lack of manganese can cause maple foliage to
turn yellow, with brown areas followed, in some cases, by
defoliation. The treatment recommended by Dr. Smith:
"If chlorosis of maples, particularly red maples, is observed
with typical green veination, the cause is quite likely manganese
deficiency.", he goes on to say, "In some cases, only a pH
adjustment is ncessary, in other instances, both pH and soil
treatment with a manganese compound will be necessary."
It is concluded that a hasty drive to comply with some gov-
ernment water standard can be harmful, or at least costly
especially when it conflicts with common sense observations.
Figure 1
Figure 2
19
-------
that at one plant the environmental government agency
demanded, over strong protest, the use of the very expensive
monitoring well shown inFigure 6. Yet at another location using
the same process and filtering lagoon, the agency permitted the
use of a simple shallow well pump and well point at a fraction of
the cost. There was no reason for their blind demand for the
expensive monitoring well, but it took them three years to back
off their original position. Appendix 1 and II describe the
process in detail with an outline description, flow sheet, and
chemical reactions of the process.
CONCLUSIONS
The United States Government Environmental Bureaucracy,
in the late 1960s and early 1970s developed a series of environ-
mental criteria that have produced a major depression in the
United States, unemployment, and a major trade deficit. Their
failure was the failure to use common sense, that is you just can't
burn more fuel and have less pollution! Our failure, that is we
the citizens, accepting their nonsense without thinking and
without common sense; it was a matter of, "They must know
what they're doing," when, in fact, they did not know what they
were doing!
The case of wastewater treatment, dam construction, energy
utilization, and use of residuals fall into the same category. The
lesson to be learned is: Don't blindly accept the standards, rec-
ommendations, directives, rules, regulations, laws, prsocedures
or any other bureaucratic concept. If you agree, fine; then gQ
along with it. But if common sense tells you they are wrong, then
use every legal weapon, appeal mechanism, the courts if neces-
sary, to fight their directives as necessary.
An open pond or lagoon, properly lined with an adsorptive
absorptive or reactive material can very often eliminate the need
for a costly treatment facility.
appendix I
Production Processes
The two main processes that produce liquid wastes are:
1. The bleaching of beeswax see flow sheet B-2.1.
2. Wax recovery from filter cake see flow sheet B-2.2.
There are four minor sources of liquid wastes and these are:
1. Waste cooling water from the petro-wax slabbers.
The cold water from the well is pumped into a 5,000 gallon
holding tank containing the water from the slabbers. The cold
well water (50-55°F) is used to maintain temperature of the
water in the holding tank at 70-75° F. This water is then reused
in the slabbers. Any overflow is discharged on the ground
surface.
1 ncidentally, a similar system is used for the beeswax slabbers
Here, the overflow water is used in the condensers in the solvent
distillation system. The overflow from the condensers is dis-
charged to the pond,
before discharging to the pond.
2. Boiler Blow Down.
The boilers (2) are blown down daily by discharging to the at-
mosphere. The blow down condensate is collected in a gutter
which leads to the pond.
The boilers are Cleaver Brooks Package Boilers: No. 1 Model
200 HP operating at 100 lbs. steam pressure; No. 2 Model 1 s0
HP operating at 100 lbs. steam pressure.
The No. 2 boiler is used as stand by. The amount of bl0vv
down—300 gallons per boiler.
Boiler treatment as per Chemical Testing Corp., 32-10 37th
Avenue, Long Island City, N.Y. and is free of chromates.
3. All process steam condensate is returned to the boilers
except in one instance. This is in the case of a wax slab scoring
device. Here the condensate is discharged to the ground surfaCe
Condensate volume—1 gallon/ hour approximately.
20 Effluent Disposal—Surface Pond
Figure 4
Blind conformance with random standards eliminates the op-
portunity to discover possible benefits of residual wastes. Costly
treatment techniques are often unnecessary. Lining a lagoon or
pond with a suitable adsorbing, or absorbing or reacting porous
bed suggests a low cost solution to many Industrial wastewater
effluents. If the lining material is in fact a residue it might
become a valuable product for other firms with a wastewater
effluent problem.
The Plant & The Process
Figure I shows the double effluent stream into a newly dug
pond in 1973. Figure 2 shows the pond and filter cake deposited
in the pond. Figure 3 shows the clear sand below the cake with
no mixed boundary layer. And, most important, Figure 4 shows
the lush foliage around an old pond. Figure 5 is a plan sketch of
the beeswax refining plant, and the location of test wells agreed
upon after several years of negotiation with the local environ-
mental groups.
One of the ironic sidelights of the various projects was the fact
Figure 3
-------
Effluent Disposal—Surface Pond 21
a
^ ^ /-qs?c<2 O
^ S/vsn/ecK*,
\
6'--20 r/L
April 5th,1977
Effluent Disposal in surface
Pond,Beeswax Process BleachinG
1977 Nat. Conf.On Industrial
Wastewater Treatment/ I.D.-DGjr
/?e>/?-/- C/a
-------
22 Effluent Disposal -Surface Pond
F/Af/SrtEP
BOTTOM &T
Z'O
4 "CM UM£& &A/£?
j^/Trz/j^s
4 "/, D. S.S. Wtth&i/ju
WE'LL SC,?££AJ
4"/,£>. Si/Ms*
&O7rTZTA
Y/£LD A LC /i/FaC/jV#
tgsreec plats
Figure 6: Typical Monitoring Well
-------
Effluent Disposal—Surface Pond 23
B-2.2 Filter Cake Extraction Process Flow Sheet
Wax & Filter Cake
Solvent extracted with tolusol
Spent filter cake steamed
to remove last traces of
solvent 1
Wast filter cake mixed with
water (320 gals, per batch-
4-7 batches/day)
Solvent wax solution
r
Solution distilled
Solvent recovered
Discharged to pond
Condenser cooling water ^
discharged to pond
Also used to suspend filtercake
When pond filled with
solid waste it is
hauled away
~~r
Wax
1
Steamed to remove last traces
of solvent
Wax slabbed
-------
24 Effluent Disposal—Surface Pond
B-2.1
Bleached Beeswax
Flow Sheet
Beeswax - Crude
Wash Water
Y
to pond
(600 gals, daily)
Filter cake
qppnt. hl.p^rh liquor
(600 gals, daily)
r
neutralized
Na2Cc>3
to pond
Water Wash
Beeswax
7 Filtered
Seeswax
Bleached
Finishing
Packaging
-------
Fly Ash Disposal System Douglas M. McBean,
Laurance C. Tallman, and
Raymoritd J. Hasenauer
Douglas M. McBean
Consulting Engineers
East Rochester, New York
INTRODUCTION
Fly ash is generally the culprit responsible for the gray-black,
discharge emitted from the smoke stacks of coal burning power
plants. It is ironic that not too many years ago—prior to our era
of environmental awareness-the productivity of power plants
was often measured in terms of the amount of smoke produced.
Not so today—this source of air pollution is so obvious that it
has been aggressively attacked by concerned citizens, compell-
ing violators to take extensive and often expensive measures to
clean up their stacks.
Mechanical dust collectors, electrostatic precipitators and
baghouses have been employed successfully to reduce fly ash
emissions to acceptable levels. These devices strip particulate
matter from the flue gas stream and collect the residue in
hoppers for subsequent removal by the plant ash conveying
system. Thus, although the visible pollution problem has been
solved, the fly ash still remains to be disposed of. In fact, it rep-
resents a more significant problem because it is concentrated
and contains a larger amount by weight of fine particles—below
10 microns in size.
The usual means employed by power plants to collect the
ashes and dust from the various hoppers throughout the plants
is to interconnect these points to a common pneumatic convey-
ing system. Subatmospheric pressure is utilized to force the
residue from the collecting hoppers into a silo for temporary
storage. It is subsequently loaded into trucks for disposal. This
seems like a straight-forward and final solution to the problem
of ash disposal. However, since the ash has been re-entrained
into the air stream by the conveying system, the question
remains of how to, once again, strip the ash from the conveying
air stream, particularly when it now contains a high proportion
of fine dust.
Spreader Stoker Fired Boilers
The problem is most severe with spreader stoker fired boilers.
The ash collected by the conveying system can vary in size from
clinkers almost as large as the conveying pipe (usually 6" or
greater in diameter) to as small as a few microns. Often the
bottom ash contains glowing embers, thereby creating a fire
hazard for fabric type collectors.
The system which offers the most practical solution, and one
which is found in many powrper plants utilizing spreader stoker
firing, employs a two-stage centrifugal separator to remove
cinders and particles to a minimum diameter of 10 microns. The
conveying air stream and particles smaller than 10 microns are
then exhausted to the atmosphere—usually via the plant smoke
stack. Of course, the validity of this is questionable from a
pollution standpoint and therefore most systems of this type
have incorporated a final device to remove the under-10 micron
size particles to an acceptable level.
At the University of Rochester Central Utilities Power
Station in Rochester, New York, a steam jet ejector was used to
produce subatmospheric pressure for conveying the ashes, and a
wet scrubber to provide both final cleanup and a means to
condense the steam.
The effluent from the scrubber was piped to a sewer which
emptied into a settling pond. The overflow from the pond was
discharged into the nearby Genessee River. Since the pond
occupied prime campus real estate, it fell victim to expansion.
To replace the settling pond, an attempt was made to utilize
settling tanks arranged in series and connected by overflow
weirs. However, a sufficient quantity of fly ash remained in sus-
pension so the outfall into the river revealed an "inky" black
stream which displayed its trace for a considerable distance.
Analysis of this effluent indicated that code requirements for
both quantity of coj»taminants and temperature of the effluent
were being violated. As a result, the University was cited by the
New York State Department of Environmental Conservation,
required to post a bond and sign a consent order agreeing to
reduce the outflow characteristics to compliant levels.
An in-depth study of the problem was made to explore alter-
native means of collection and disposal. The system being
employed has been in wide general use for many years and
similar problems, including code violations, are not uncommon.
Because no promising alternative could be found, attention
was focused on the existing system and attendant plant opera-
tions.
Figure 1 is a schematic elevation of the essential parts of the
system in use at the University of Rochester. As stated, it is
typical of systems in use today. In this case, subatmospheric
pressure is produced by a steam jet ejector (4) which reduces the
pressure in the ash line (1) to approximately 23" Hg. absolute.
Ashes and cinders are forced from open hoppers into a primary
collector (2) which separates the larger cinders and particles
from the air stream. The smaller particles and air continue to the
collector (3). The remaining fine particles enter the steam jet
ejector, together with the transport air, and are conveyed
directly into the wet scrubber (5). The scrubber is supplied with
city water through pipe (17) at an incoming temperature of
60° F. to 75° F. (depending on the time of year). The water
condenses the steam and entrains most of the remaining fine
particles. The effluent from the scrubber passes through a pipe
(6) to a sump (7) and then is discharged into the storm sewer (8).
The transport air containing some fines exits through a pipe (9)
to atmosphere.
25
-------
26 Fly Ash
During the ash removal period of one to two hours per eight
hour shift, the steam jet ejector is cycled on and off. The ON time
is approximately 75 seconds, the OFF time is approximately 15
seconds. The reason for cycling is to allow the primary and sec-
ondary collectors to dump the cinders and ash into the storage
silo (10) through automatic doors or valves in the bottom of the
collectors. These dump valves are normally open, but are closed
when the steam jet is in operation. As the collectors dump into
the silo, the air displaced is released through a bag filter
aseembly (11) to the atmosphere.
When sufficient ashes have accumulated in the silo, a dump
truck is placed in the proper position under an opening (12) to
receive the ashes discharged from the tumbling barrel (13). The
tumbling barrel is fed through a rotary feeder (14) from the
hopper (15) in the bottom of the silo. When the tumbling barrel
is activated and the feeder is in operation, city water is
introduced through a line (16) to the sprays in the tumbling
barrel to wet the ashes and cinders. It is interesting to note that
approximately 550 gallons of city water are used to wet down
each 10 ton truckload of ash toensurethat the ashes remain with
the truck en route to the dump.
At the time of the study, the plant was operating at less than
half capacity. By metering the city water used by the scrubber
and analyzing the effluent, it was determined that at the existing
ste im production rate, approximately 27,000 gallons per day of
city water were being used to collect and carry off 700 lbs. of fly
ash The temperature of the effluent was 145° F.
Because of the location of the scrubber in relation to the jet
eiector a large percentage of the required water was being used
to condense steam. Furthermore, the possibility of recirculating
scrubber water to increase the particulate loading, and reduce
the quantity of water required by the system, was inhibited by
the requirement to condense steam. The water would be boiling
during the second pass.
As part of the investigation, because such large quantities of
citv water were being used, alternate sources for water were
sought It did not take much searching to find that more than
enough water would be available from boiler blowdown. This
source was being wasted at the time and also was found to be
discharging to the river in violation of temperature restrictions.
A plan evolved to relocate the steam jet ejeclor to follow the
scrubber. This eliminated the requirement to condense steam
and enabled recirculation of the scrubber water. Both steps
substantially reduced the quantity of water used by the system.
To determine the requirements and potentials of a recirculat-
ing system, the anticipated maximum coal usage was estab-
lished at 240 tons per day. Analysis of the effluent from the
existing scrubber revealed that 3652 ppm of particulates were
being deposited in the scrubber water when the system was in
operation, with 51 gpm of city water being supplied to the
scrubber. From plant records, the average ash removal time per
ton of coal burned was determined by month and an R.M.S.
value of .046 hours per ton of coal burned was calculated, based
upon prior years' usage. Therefore the quantity of fly ash
recovered per day was 1028 lbs.
Figure I
240 tons
day
.046 hrs
ton
X 3652 parts ^
10"
8.33 lb. y 60 min.
* = 1028 lbs./day
gal.
hr.
Since the steam jet cycles ON 75 seconds and OFF 15 seconds
during the ash removal cycle, this total must be reduced by
75/90 which equals 856 pounds per day anticipated when
burning 240 tons of coal per day.
To be on the conservative side and also to account for
scrubber efficiency, since a new, higher-pressure-drop unit
would be employed in a revised system, an assumption was
made that the measured concentration represented only about
85% of the total fly ash going to the scrubber. Dividing by this
gave a maximum figure of 1000 pounds per day.
Based upon the recommendation of the scrubber manufac-
turer, about 15 gpm of water per 1000 CFM of air would be
required, with a maximum buildup of particulates recirculating
to the scrubber of 20%. With an average flow of 2500 ACFM of
air, about 40 gpm would be required.
The normal procedure at the University of Rochester is to
remove ashes from the silo several times each week but not on
weekends or holidays. Therefore, if the revised system required
storage of the 1000 lbs. per day of collected fly ash, then over a
long weekend 3000 lbs, would accumulate. Using an
*e average
specific gravity for fly ash of 2, this quantity of fly ash repre.
sents 24 cu. ft. of storage capacity. Additionally, to achieve tk„
Srf — — ------
, -—-—~ uwiucve th*»
20% maximum concentration specified for the recirculat
system, this amount of fly ash would have to be suspendeii°n
1800 gallons of water. This figure does not account for 'n
settling of the particulates.
3000 lbs. w gal.
any
.20
8.33 lbs
= 1800 gal. water
-------
Fly Ash 27
Tests were conducted to determine the settling rate of the fly
ash and it was found that complete settling occurred in 4 hours.
The ash system would be quiescent between ash removal periods
for approximately this length of time. Therefore, concern could
be focused on designing the hydraulic system to avoid excessive
agitation which might resuspend the settled particles, and on
supplying sufficient water in the recirculation system to keep the
concentration below 20%. Since 550 gallons of water are used to
wet down the ashes and it is common practice to remove two
loads in succession, a capacity of 1100 gallons appeared feasible
for a settling tank. Adding to this quantity the 24 cu. ft. of settled
fly ash, the required tank capacity was increased to 1300 gallons.
Figure 2
Calculating the fly ash concentration at the end of a one-hour
ash removal period for this amount of water, and assuming
complete settling has occurred since the last ash removal period,
and that there is zero resuspension due to agitation, produces a
result of 1.82%.
1000 lb. particulates
6 removals
1
1
1000
8.33 lb.
-X 100= 1.82%
This optimum figure should provide sufficient margin to
allow for incomplete settling and/ or resuspension due to agita-
tion.
Matehmatically, it appeared possible that a revised system
employing recirculation offered the potential of completely
eliminating the effluent to the river. In concept, this new system
would utilize water already being wasted by the power plant
operation (blowdown water) to supply the scrubber; utilize
recirculation in the scrubber system to minimize the total
quantity of water required by the system; store a sufficient
quantity of this water to provide the proper settling time; and
provide the water required to not only wet down the ashes but
also flush the sediment from the holding tank. Proper sizing of
the equipment should result in no effluent going to the sewer.
The new system is shown in Figure 2. The existing steam jet
ejector (4) has been located downstream of a new high-velocity
scrubber (5). As part of the study, it was determined that a
sufficient sum of money could be saved to warrant consid-
eration of the use of electrically driven fans in place of the steam
jet ejector. Although this arrangement is shown in Figure 2,
inclusion of the fan system has been reserved for a future time,
inasmuch as the steam jet was already available.
The initial ash separation is still achieved by cyclone collec-
tors (2 and 3), with the remaining fine particles being carried by
the air stream to the scrubber inlet.
Referring to Figure 3, two tanks are provided: one scrubber
tank (21) to hold a quantity of the mixture of ash and water
emitted from the throat of the wet scrubber; and one settling
tank (24) sized to provide ample settling time while also storing a
sufficient quantity of water to wet down the ashes. An inverted
cone is provided in the scrubber tank to aid in separating the
solids from the water. Water for recirculation to the scrubber
throat is drawn from the center of the tank just below the apex of
the cone. Due to space limitation, the scrubber tank is attached
directly to the bottom of the wet scrubber assembly (23).
A reservoir (19) is provided in the top of the settling tank. The
water level in the reservoir and tank is controlled by a weir (18)
in such a manner that when the tank is filled with blowdown
water, spillover occurs from the reservoir to the tank. When the
system has the required quantity of water and is operating,
spillover occurs from the tank to the reservoir. Bubbler controls
(26 and 26A) are arranged to operate the valve (27) which
provides blowdown water to the reservoir. Bubbler control
(26A) overrides bubbler control (26). This arrangement ensures
that the water level in the tank will remain above the inlet from
the scrubber tank to the settling tank, and also that water will
always be available for wetting down the ashes. The inlet from
the scrubber tank is oriented tangentially to provide a centrifu-
gal (swirling) effect to the water in the settling tank, thereby
accelerating separation of the solids.
To complete the hydraulic circuit, a line is taken from the
bottom of the reservoir, through the valve (20) to the scrubber
tank. A float chamber and float (22) is employed to operate the
control valve (20) and maintain a constant liquid level in the wet
scrubber. A city water circuit is provided for backup purposes
only.
During ash removal, the system operates for approximately
one hour. This is repeated twice each shift. The recirculation
pump (28) runs continuously during this period, delivering 40
gpm to the scrubber throat. To minimize wear in the scrubber
assembly and hydraulic circuit, the recirculation pump is
provided with two inlets—one supplying 20 gpm from the
scrubber tank and one supplying 20 gpm from the reservoir (19).
This effectively reduces the concentration of solids in the
recirculation system. A pump (25) delivers 20 gpm from the
bottom of the scrubber tank to the settling tank, maintaining the
hydraulic balance. Because the pump (25) would be required to
work against a widely varying head if it ran during the off period
of the jet ejector, it is cycled on and off with the steam jet.
The saturated air leaving the scrubber throat is forced
through a demister (29) to remove any remaining water droplets.
The air stream then mixes with the steam in the venturi of the jet
exhauster. The mixture passes through a muffler (30) into the
stack where it exhausts to atmosphere.
When ashes are unloaded from the silo to a truck, 550 gallons
of water and sediment are pumped (31) from the settling tank
.J
Figure 3
-------
28 Fly Ash
and sprayed over the ashes emptying from the silo. The trou-
blesome fly ash is redistributed into the heavier ash for final
disposal. (In this application, the ashes are stored by the removal
company and recycled for use in constructing road foundations
and school athletic tracks.) Since no effluent goes to a sewer,
only the exhaust air/steam mixture is subject to code consid-
erations. A recent test of the system by an independent testing
company determined the actual measured rate of emission to be
.64 pounds per hour against the maximum allowable rate of 4.3
pounds per hour.
Design Considerations
Important design considerations for anyone desiring to utilize
a system such as this are as follows:
1. Ideally, the scrubber and sedimentation tanks should be
located in the basement of the plant so that a barometric
leg of sufficient height exists between the scrubber throat
and the scrubber wet well to maintain a constant head on
the inlet to the pump (25).
2. The velocity from the throat of the scrubber is about
15,000 fpm. It was necessary to design a plastic wear piece
for the elbow at the outlet of the scrubber. A less expensive
solution might be to provide a wet elbow.
3. The pH of the effluent should be maintained between 8—9
to avoid system corrosion. Even using high pH blowdown
water is insufficient when ashes are not moved over a
weekend, as the water in the sedimentation tank changes
from a pH of 12 to a pH of 3 in about 24 hours.
To overcome this problem, 2500 ppm of sodium hydroxide
is maintained in the recirculating effluent. The sodium
hydroxide in a 50% solution is introduced in the throat of
the scrubber by a chemical metering pump.
In situations where oil is burned over coal, the fly ash
becomes coated with a slight oil film causing it to float in
the settling tank. By introducing the sodium hydroxide at
the scrubber throat, the oil is effectively dissociated from
the fly ash, restoring normal settling characteristics.
The metering pump must be located in such a wav tha»
sufficient head exists, to prevent low pressure in ,u
scrubber throat from overriding the pump and permitting
entrance of uncontrolled amounts of the chemical solu-
4. Careful consideration must be given to the selection *
vive* fittings and piDe. due to the extreme^
Caretui consiaerai" B,vC., lu lll<=
pumps, valves, fittings and pipe, due to the extrernelv
abrasive fly ash laden effluent. Chemical pumps utili7i„„
CD4M (Cast Chrome-Nickel Alloy) impeller and hous n!
or rubber lining provide satisfactory life. Rubber hose a J?
f,ttines must be used When rubber u d
or rubber unmg |n«"»v mv., nuuuv.i uuscana
rubber-lined fittings must be used. When rubber lining is
not possible, 316 stainless provides an adequate but
expensive substitute.
5. Since some steam condenses in the stack, the water formed
collects some of the particulates that are being carried in
the steam/air stream. The water and particulates will
collect at the bottom of the stack and must be drained to
the scrubber chamber to avoid carryover to the atmo-
A better and less expensive solution would be to exhaust
into a smoke stack. This would eliminate the need for a
muffler and for concern about carryover. At the University
of Rochester, no single stack is always in use so a potential
freeze-up problem would have been created by exhausting
into a stack. Even in warm climates the stack should be one
that is maintained hot, to avoid the potential accumulation
of carryover moisture and ash.
CONCLUSION
Although the cost saving achieved by using blowdown water
is not too significant, it serves as an excellent means of disposing
of undesirable waste water.
The system described herein offers a total and final means to
dispose of the "pesky" fly ash waste from stoker fired, coal
burning power plants. It is universally applicable as an adjunct
to the conveying system described; reasonable in cost and, most
importantly, ecologically sound.
-------
An Evaluation of
Atmospheric Evaporation for
Treating Wood Preserving
Wastes
INTRODUCTION
The disposal of wastewaters by atmospheric evaporation is
one of a few treatment processes which produce no discharge. A
number of industries use it today because, when properly ap-
plied, atmospheric evaporation is a simple and economical
means of handling a difficult to treat wastewater. This paper ex-
amines the design of an atmospheric evaporation system
indicating the proper procedures. Also, the application of at-
mospheric evaporation to wood preserving wastes is presented
to determine if this process can be applied to a difficult
wastewater problem.
Atmospheric Evaporation as a Wastewater Treat-
ment Process
The concept of atmospheric evaporation as it is typically ap-
plied is quite simple. The wastewater is stored in shallow ponds
where exposure to the atmosphere slowly evaporates it. This
type of treatment is quite restricted in its application because it is
suitable only for locations where evaporation is much greater
than precipitation. However, if the wastewater is sprayed into
the air above the pond, evaporation can be increased many
times. This forced evaporation by spraying is a modification of
atmospheric evaporation, but it can be referred to as atmo-
spheric evaporation for simplicity.
Since this type of atmospheric evaporation with sprays is not
in widespread use, formal design procedures for such a system
do not exist. One purpose of this paper is to outline the design
procedure. The design should include the following elements:
(1) determination of the required pond area and the number
of spray nozzles,
(2) removal of compounds which are potential air pollution
sources,
(3) prevention of excessive drift losses,
(4) eliminating groundwater seepage, and
(5) optimization of the energy-evaporation area relationship.
Each of these elements are important to the design and must
be given proper consideration.
The determination of the pond configuration is not as simple
as one might think. The pond size will depend upon an annual
mass balance between water which enters the pond as waste-
water or rainfall and water which is lost by evaporation. The two
influent flows should be based upon a frequency analysis of
existing data. The evaporation loss can be calculated given ap-
propriate weather data, the spray height, the spray nozzle mass
transfer coefficient, and the spray nozzle density (number per
unit area). In order to have a well designed pond, good weather
data is needed. The meteorological parameters required are
Pete A. Shack
Environmental Science and Engineering,
Inc.
Austin, Texas
and
Tom D. Reynolds
Texas A&M University
College Station, Texas
temperature, relative humidity, wind speed, wind direction
frequency, and precipitation.
The evaporation that will occur from a pond with sprays is
given by an equation developed by Lof et al.3 This equation
takes into account the change in humidity and the resulting
decrease in evaporation as the air passes over the pond. Surface
evaporation is also accounted for in this equation. The equation
is applied in an iterative fashion to optimize the pond length.
AH design parameters except length must be chosen. Then for
various trial lengths the evaporation is calculated by month and
adjusted for wind frequency. The water balance is computed on
a monthly basis to give the net change in pond depth over a
year's operation. A plot of several lengths and the resulting
depth changes will indicate the length for which zero net change
in depth occurs. This is the optimum pond size. The procedure
may be repeated for various combinations of spray height,
nozzle density, mass transfer coefficient, and pond orientation.
A computer program is recommended for this purpose.
The second element of spray pond design is the removal of
substances which lead to air pollution. This can best be evalu-
ated by actual measurement of air contaminants as the waste-
water is evaporated. Obviously, any readily volatile substances
such as oil can present a problem and should be removed.
Removal does require an additional process'prior to evapora-
tion. Skimming, coagulation, precipitation, oxidation, and/or
sedimentation are possible pre-evaporation steps.
The next element of the evaporation system design is the
prevention of drift loss. Proper operation of the pond is as
important as the distance between the edge of the pond and the
closest nozzle. The design should be based on a maximum wind
speed of 12 to 15 miles per hour. When winds above this occur
the spraying should be stopped. Guidelines for the distance from
the closest nozzle to the edge of the pond can be found in the
literature.3-'1 Adequate distance should be allowed within the
pond or a collection zone should surround the pond with
provision for recycling the drift loss falling in this zone. Many
ponds are not designed or operated for proper control of drift
loss.
The seepage of groundwater into or out of the pond must be
prevented. Lining ponds with impervious clays and synthetic
materials is a common practice in many sanitary engineering
projects and should present no technical problem.
The final design task is the optimization of energy utilization
and land area. This can only be achieved by developing several
designs for different spray heights and determining the energy
required to operate each. No direct relationships have been de-
veloped to optimize this trade-off, so an iterative process must
be used. The limitations on energy and land availability make
this optimization a worthwhile investment of time and money
-------
30 Wood Preserving Wastes
during the design procedure.
For further information concerning design details the reader
is referred to the Texas Water Resources Institute report titled
"Treatment of Wood Preserving Wastewater.'"
Atmospheric Evaporation Applied to the Wood
Preserving Industry
As an example of how atmospheric evaporation with sprays
can be applied, the wood preserving industry will be consid-
ered.
_ The process of preserving involves impregnating the wood
cells with substances inhibiting the growth of organisms which
cause decay. Some common preservatives are creosote, coal tar,
pentachlorophenol (PCP), and certain metallic salts. All of
these substances are quite toxic and many plants treat with more
than one preservative.
The objective of preserving wood is to make the wood last
until a new tree can be grown to replace it. Pressure is applied to
force the preservative into the outer layers of wood. The
preservative may be carried by petroleum product or by water.
This research deals primarily with the handling of wastes from
oil-borne preservatives.
The wood preserving industry is a small component of the
wood products industry which produces numerous items from
paper to plywood. There are about 375 wood preserving plants
across the country most of which lie in the forested regions of the
east, south, and west as shown on the map in Figure I. The
majority of plants employ approximately 20 persons, of which
eighty percent or more are production workers, largely
unskilled. The importance of these facts with respect to the
waste treatment problem is that the size of the industry restricts
the solution. Unless great changes are to be brought about in the
industry, the solution to pollution control must be simple, easy
to operate, and economical.
The wood preserving process can be broken down into six
steps: (I) debarking and shaping, (2) seasoning and preparation,
(3) preconditioning, (4) preserving or impregnation, (5) clean-
ing. and (6) cooling. One or more steps may be combined in one
operation and there are many different processes for each step.
A process flow chart is given in Figure 2. Note the wastewaters
indicated by dashed lines. While some steps produce both oily
and dirty wastewater streams, others may produce one or the
other type of wastewater stream.
An examination of the available data on the wastewater pro-
duced by wood preserving processes reveals how large a task
treatment is. The typical raw waste from a preserving plant has
free oils, contains emulsified oils, has a high organic content, is
toxic to some degree, and has an acid pH. The range in
characteristics of this wastewater are given in lable 1. This
process wastewater is not easily handled by any conventional
treatment process.
Usually the raw waste is placed in a gravity-type oil water
separator to recover free or non-emulsified preserving oils. The
wastewater thai emerges from the separator is a "coffee with
milk" color emulsion which closely resembles the raw waste.
Applying atmospheric evaporation to this waste is not a simple
matter. The laboratory phase of the research was to determine
the optimum configuration for an atmospheric evaporation
system. This included bench scale evaporation tests to examine
the emission of hydrocarbons and any tests or pretreatments
necessary to prepare the wastewater for evaporation.
The results of the laboratory tests indicated that coagulation
to remove the oil emulsion and related apolar compounds is nec-
essary to restrict hydrocarbon emissions. Coagulation with
either ferric chloride and lime or commercially prepared
polymers was found to remove 40 to 80 percent of the chemical
oxygen demand (COD). In batch tests on coagulated waste-
water the change in COD and total organic carbon (TOC) was
directly proportional to the removal of water and was relatively
f AA Forested Areas and Wood Preserving Plants in the United States
Figure 1: Geographical Distribution of Maj
-------
Wood Preserving Wastes 31
DE3ARKING
SEASONING
PRE-
_
e
c;
CONDITIONING
shaping
PREPARATION
.
"1
"T
WASTEWATERS-
RINSE WATER
COOLING V.'ATER
WOOD CHIP SLURRY
CLEANING
COOLING
¦1
I
-i.
b Oily
* T*»
! Wa'ers
I Dirty
. -j— —o»
Waters
SAPWATER
CONDENSATE
CONDENSED VAPORS
CONDENSATE
SAP"'ATER
COriD'ilv'SED VAPORS
CONDENSATE RUNOFF
CONDENSED VAPORS
SUBPROCE?S^S:
DRUM BARKERS
RING BARKERS
BAG BARKERS
CUTTERHEAO
BARKERS
HYDRAULIC
BARKERS
AIR SEASONING
KILN DRYING
STEAM-VACUUM
CYCLING
EOULTOHIZIMG
VAPOR DRYING
TUNNEL DRYING
MECHANICAL
PREPARATION
CLOSED STEAMING FULL CELL
OPEN STEAMING EMPTY CELL
LOADING a SEALING LP GAS
CYLINDERS
FLASH STEAMING ATMOSPHERIC
FINAL VACUUM IN-SITU
UNLOADING
Figure 2: Typical Pressure Wood Preserving Process Flow Chart5
Table I: Reported Characteristics of Wood Preserving Waste-
waters from Oil-Borne and Water-Borne Preservative Treat-
ments
INITIAL COD CONCLNTRATIOM (rng/l)
(i)
flow,
CUD, mg/1
nOUi(, HKj/1
Phono h,, i:k]/1
Oils, mg/1
[)isr.olvc'd Solids, incj/1
Suspended Solids, nig/]
I'M
Coppur (Cu)» iuy/1
Chro:iiliin (Cr), mg/1
Arsenic (As), mg/1
riuorint' (f), mg/1
Phosphates (PQ^), nuj/1
Ammonia (Nllj), mg/1
Oi1-Borne
(2)
Water-Borne
(3)
1 -lb
900-110,000
350-26,800
13-2,350
6-3,060
213-18,350
8-1,844
2.1-7.4
20-50
1,700-4,100
<1.0-30
5.0-5.3
0-170
375-475
180-300
590-740
640-820
1,260-1,340
Note: Oil-tutruo valm,r lused on 26 wastcv.'u lers reported in the
1 itLT.ituiv i11c 1 udimi avosoto, penUchloroiilirnol, and mixed waste-
waters. U.iter-hoi'Mu f inures alter Jones and Frank (2) and Russell (6)
constant as the waste was evaporated. This gives a zero order
(linear) removal relationship between water evaporation and
volatile stripping. The degree of volatile stripping as measured
by COD or TOC was directly related to the initial concentration
as shown in Figure 3. The use of such a result can only produce
conservatively high emission figures and is justified on this basis.
The treatment scheme developed for applying atmospheric
IOOO 2000 3000
INITIAL TOC CONCENTRATION (mg/1)
4000
50 OC
Figure 3: Relationship Between Evaporation Ratio and Initial
Concentration in Batch Evaporation Tests
evaporation to wood preserving wastes is shown in Figure 4.
Included in this diagram are facilities for bulk oil recovery,
coagulation and sedimentation, and evaporation using sprays.
Also shown are holding ponds for non-oily process wastes and
contaminated plant drainage which is intermittantly fed to the
spray evaporation ponds or coagulation tank, as necessary.
The environmental hazards of using evaporation ponds to
dispose of toxic and otherwise troublesome wastes have not
been well documented. Fugure research will be the key to
understanding and foreseeing problems in this area. Proper
design and operating techniques can minimize the chances for
-------
32 Wood Preserving Wastes
drift losses, seepage into groundwater, and inefficient use of
energy, but at this time there is no means of preventing the small
amounts of preservative remaining in the wastewater after
coagulation from volatilizing into the atmosphere to some
degree. In the case of pentachlorophenol wastewaters,sufficient
concentrations of pentachlorophenol and any dioxin contami-
nants would preclude the use of atmospheric evaporation. It
should be noted that the problem of volatilization of preserva-
tives exists with activated sludge treatment also.
An evaporation system like that in Figure 4 was designed for a
hypothetical wood preserving plant of typical size located near
College Station, Texas. Cost estimates for this design were made
for comparison with an activated sludge treatment plant to treat
the same organic loading. The cost estimates indicate the
evaporation system would cost one-half to two-thirds of the
construction cost and only about one-third the operating cost of
an activated sludge system.
taken to prevent air pollution. One method of limiting air
pollution which shows promise is coagulation and sediments-
tion.
references
1 Development Doc ument far Effluent Limitations Guidelines
and New Source Performance Standards for the Plywood,
Hardhoard, and Wood Preserving Segment of the Timber
Products Processing Point Source Category, U.S. Environ-
mental Protection Agency, Washington, D.C., April, 1974.
2. Jones, R. H., and Frank, W. R., "Wastewater Treatment
Methods in the Wood Preserving Industry," Proceedings,
Conference on Pollution Abatement and Control in the
Wood Preserving Industry, Mississippi State University,
1970, pp. 206-216.
3. Lot, Ci. O. G., Ward, J. C., Karaki, S., and Dellah, A.,
"Concentration of Brines by Spray Evaporation,"' Colorado
State University, United States Department of Interior,
Washington, D.C., January 1972.
4 Perry, J. H., "Psychrometry," Perry's Chemical Engineers'
Handbook, McGraw-Hill Book Co., New York, 1963, pp.
15-2 15-23.
5. Reynolds, T. D., and Shack, P. A„ "Treatment of Wood
Preserving Wastewaters," fcchnical Report No. 79, Texas
Water Resources Institute, Texas A & M University,
October, 1976.
6. Russell, L. V., "Treatment of CCA-, FCAP-, and RF-Type
Wastewaters," Proceedings, Conference on Pollution Abate-
ment and Control in the Wood Preserving Industry, Missis-
sippi State University, 1970, pp. 244 260.
7. "Wood Preservation Statistics, 1974," Proceedings, AWp/v,
Vol. 71, 1975, pp. 225-263.
BIBLIOGRAPHY
1. Best, C. W., "Water Use in Western Wood Preserving
Plants," Proceddings, AWPA, Vol. 68, 1972, pp. 137-142,
2. Dust, J. V. and Thompson, W.S., "Pollution Control in the
Wood Preserving Industry, Part 11, ln-Plant Process
Changes and Sanitation," Forest Products Journal, Vol
22, No. 7, Vol. 22, No. 12, Dec. 1972, pp. 25-30.
3. Dust, J. V. and Thompson, W.S., "Pollution Control in the
Wood-Preserving Industry, Part 111, Chemical and Physi_
cal Methods in Treating Wastewater," Forest Products
Journal, Vol. 22, No. 12, Dec. 1972, pp. 25-30.
4. Dust, J. V. and Thompson, W. S., "Pollution Control in
Wood-Preserving Industry, Part IV, Biological Methods erf
Treating Wastewater," Forest Products Journal, Vol.
»» r\ 1071 nn SQ—
23,
Figure 4: Treatment System Schematic5
SUMMARY
The advantages to using atmospheric evaporation for dispos-
ing of industrial wastes should be clear. They are (!) no
discharge to waterways, (2) simple construction and operation,
and (3) inexpensive treatment for small flows. Some obvious
disadvantages are (1) large land requirements, (2) air pollution
potential, and (3) geographical limitations.
The conclusions of this study are as follows. Atmospheric
evaporation is a technically feasible and reasonable treatment
process for some wastewaters. The ideal case would be an
industry with low flows, a difficult to treat wastewater, few
volatile contaminants in the waste, readily available land, and a
suitable climate. Secondly, wood preserving wastewaters are
amenable to atmospheric evaporation but precautions must be
No. 9, Sept. 1973, pp. 59-66.
5. "Effluent Guidelines and Standards, Timber Prod^-j
Processing Point Source Category," Federal Register V «
39, No. 76, April 18, 1974. ' ol-
6. Fisher, C. W., "Soil Percolation and/or Irrigation
Industrial Effluent Waters- Especially Wood Treat'
Plant Effluents," Forest Projects Journal, Vol. 21 No'**?
Sept. 1971, pp. 76-78. ' '
7. Fisher, C. W. and Tallon, G. R., "Wood Preserving P|^
Wastewater Problems—Some Solutions," ProceediJ1**
AWPA, Vol. 67, 1971, pp. 92-96.
8. Gaudy, A. F,, Scudder, R., Neely, M. M., and Perot, J
"Studies on the Treatment of Wood Preserving Wast" «
Paper presented at the55f/i National Meeting on Water**'**
Wastewater Technology, AlChE, 1965. a**d
9. Gloyna, E. F., and Malina, J. F„ "Petrochemical Wast
Effects on Water, Pollution Control, Part 3," Indus***
Water and Wastes, Jan.-Feb., 1963, pp. 14-22. ^
-------
Wood Preserving Wastes 33
10. Halff, A. H., "Slow Sand Filtration of Wood-Treating
Plant Waste," Proceedings, AWPA, Vol. 55,1959, pp. 184—
188.
11. Halladay, W. B., and Crosby, R. H., "Current Techniques
of Treating Recovered Oils and Emulsions," Proceedings,
American Petroleum Institute, Vol. 44 (III), 1964, pp. 68-
73.
12. Henry, W. T., "Treating Processes and Equipment," Wood
Deterioration and Its Prevention by Preservative Treat-
ment, Volume II Preservatives and Preservative Systems,
Syracuse University Press, 1973, pp. 279-298.
13. MacLean, J. D., Preservative Treatment of Wood by
Pressure Methods, Agriculture Handbook No. 40, Ameri-
can Wood Preserver's Institute, McLean, Virginia,
December 1952.
14. Middlebrooks, E. J., "Wastes from the Preservation of
Wood," Journal of Sanitary Engineering Division, ASCE,
Vol. 94, No. SA1, Feb. 1968, pp. 41-56.
15. Miller, M. D., "An Exemplary Waste Treatment System,"
Proceedings, AWPA, Vol. 70, 1974, pp. 180-184.
16. Steck, W., "The treatment of Refining Wastewater with
Particular Consideration of Phenolic Streams," Proceed-
ings, 21st Industrial Waste Conference, Part Two, Purdue
University, Lafayette, Ind., pp. 783-790.
17. Thompson, W. S., Proceddings, Conference on Pollution
Abatement and Control in the Wood Preserving Industry,
Mississippi State University, 1970.
-------
Disposal of Particulate Waste
From an Air Pollution
Cleaning System
Murali D. Atluru
Environmental Laboratories, Inc., New
Haven, Connecticut
and
Abdul Quadir
Flaherty Giavara Associates, P.C., New
Haven, Connecticut
INTRODUCTION
Increased emphasis on clean air in recent years has sharply
increased the installation of air pollution control devices on the
exhaust flue gas streams at manufacturing plants. Often times,
these air pollution control devices have been installed hastily
without due regard to the disposal of the waste products
removed by these devices. The waste products recovered by the
air pollution control devices are either in solid or liquid form,
more often than not containing products harmful to the envi-
ronment if disposed of improperly. This study investigates sev-
eral methods of disposal of the solid waste generated from an
electrostatic precipitator installed on the exhaust flue gas stream
at a large manufacturing plant in the State of Connecticut.
The plant is located adjacent to the Thames River and
manufactures vacuum insulated glass bottles for use in contain-
ers. The plant operates 24 hours a day for 365 days a year. The
plant's glass making furnace is equipped with an electrostatic
precipitator on the exhaust flue gas stream to remove the
particulates. This particulate waste is white and very light.
Presently, approximately 300 lbs. of waste is generated daily and
is being recycled to the furnace.
The electrostatic precipitator has been in service for about one
year and the recycling of its waste product has not created any
problem for the quality of the product. However, the waste
contains a significant quantity of sulfates which might increase
sulfur oxides concentration in the flue gases.
The management of the company, being aware of the fact that
this waste may adversely affect the product quality and/or the
quality of air, decided to undertake a study to develop an alter-
native disposal method for the waste.
The purpose of this study was to identify alternative methods
of disposal for the waste and define the most feasible alternative
method. The scope of the study was to analyze the chemical
composition of the waste; identify and evaluate alternative
methods of waste disposal; select the most feasible method
acceptable to regulatory agencies and develop preliminary cost
estimates.
Waste Characteristics
The chemical and physical characteristics of a waste are of
prime importance in determining a waste disposal method.
Therefore, a program of laboratory testing was designed and
various physical and chemical parameters of the waste were an-
alyzed in the laboratory. The sample for the chemical composi-
tion was prepared by dissolving 10 gms of waste in one litre of
distilled water and digesting it with nitric and hydrochloric acids
to solubilize the waste completely. The sample for the water
soluble portion was prepared by dissolving the waste in distilled
water and then filtering the solution through a 0.45 micron filter.
The filtrate was then acidified with nitric and hydrochloric
acids. The samples were tested on an atomic absorption
spectrophometer for various metal ions. Various other elements
were determined in accordance with the procedures outlined in
the "Standard Methods for the Examination of Water and
Wastewater" published jointly by APHA, AWWA.and WPCF.
These tests revealed that the waste density is 7.83 lbs./cu. ft. and
the waste is 89% water soluble. The pH of the waste solution was
8.25. The results of the chemical analysis are presented in Table
1.
These test results indicate that disposal of this waste product
at a landfill without any precautionary measures would result in
the waste eventually contaminating the ground as well as the
surface water. The major waste constituents are sulfates of
sodium and potassium, and boron oxide. Various heavy metals
comprise a small fraction of the waste. The total nickel content is
0,1 lb./300 lbs. of the waste. Most of the heavy metals are in
insoluble form except nickel which is about 70% water soluble.
Therefore, it appears that leachate resulting from the waste
would contain some nickel along with other salts. The pH of the
waste is slightly alkaline.
Disposal Methods
The following methods of waste disposal as an alternative to
recycling were considered;
Incineration
Deep Well Injection
On-Site Recovery of Waste Products
Marketing the Waste as Raw Material
Disposal by Private Contractors
Landfilling
Ocean/River Disposal
A description of each of these alternatives follows:
Incineration
This method relies on burning the combustible matter and
transforming it into gaseous form. Only inert matter is left
which is considerably small in volume. Due to the inorganic and
non-combustible nature of the waste, this method was not con-
sidered a viable alternative.
Deep Well Injection
This method consists of pumping the liquid waste deep below
the surface into such a geological formation that the pumped
liquid would not contaminate the groundwateraquifer. Consid-
erable geological information is required to determine the
suitability of this method. No such information was readily
34
-------
Particulate Waste 35
TABI.E I: Chemical Composition of Waste
Element
Total
wt. %
Water Soluble
Metals Wt. %
Aluminum
0.0070
Not detected
Arsenic
0.1200
Not detected
Boron
13.4000
—
Barium
0.0100
0.0040
Calcium
0.0028
0.0028
Cadmium
Not detected
Not detected
Chloride
0.3000
Cobalt
0.0010
0.0010
Chromium
0.0050
0.0016
Copper
0.0030
0.0010
Iron
0.0590
0.0050
Potassium
7.9000
7.3000
Magnesium
0.0080
0.0080
Manganese
0.0010
0.0005
Sodium
26.0000
19.0000
Nickel
0.0340
0.0240
Lead
0.0240
0.0050
Silicon
0.1400
—
Sulfate
32.0000
Zinc
0.0060
0.0012
Oxide &
Fluorides
19.9792
...
100.0000%
26.3541%
available in the area. Since development of such information
would have required a substantial effort, this method was not
pursued further.
On-Site Recovery of Waste Products
This method consists of converting the various waste prod-
ucts into a salable form. Since the quantity of the waste is
relatively small and the waste contains several elements, this
method was not pursued further.
Marketing the Waste as Raw Material
This method consists of selling the waste to some other
manufacturing plant, which can use it as a raw material in its
process. This method is not very common for industry, possibly
due to trade secrets. Also, the waste may change in quality and
quantity which would create problems for the waste supplier as
well as the receiver. The waste in question is relatively small in
quantity and contains a variety of metals and salts. Therefore,
this method was not considered a viable alternative.
Disposal by Private Contractors
Due to stringent pollution abatement requirements by the
regulatory agencies, private contractors are operating facilities
for disposal of hazardousand special wastes. These contractors
collect the waste from small waste generators who cannot eco-
nomically provide waste handling facilities. These waste han-
dling facilities are normally approved and licensed by the
respective states where they are located.
An inventory of these contractors indicated that none of them
had any facilities within the State of Connecticut to handle this
type of waste. The nearest locations were in Lowell, Massachu-
setts; Bridgeport, New Jersey; Model City, New York; and
Niagara Falls, New York. These facilities are 120 miles to 500
miles away from the plant site. These contractors were contacted
and a waste sample, along with its characteristics, was sent to
each one. Two facilities, one in Lowell, Massachusetts and the
other in Bridgeport, New Jersey, responded with positive pro-
posals for accepting the waste. The major requirement was to
ship the waste in suitable containers for easy handling. One
contractor required that the waste be in a liquid form and be
shipped in steel drums. Ultimate disposal was to a special
chemical wastes landfill without treatment. The other contrac-
tor required the waste to be packed in plastic bags and be
shipped in a truck load. The waste was to be incinerated and the
residue to be landfilled in a chemical wastes landfill.
Shipping the waste in plastic bags, treating it at the contrac-
tor's facility and then disposing the waste at the landfill was con-
sidered a better option. This option required that the waste vol-
ume be reduced foreasy handlingand packaging in polyethylene
bags. A pelletizer was considered to be appropriate for this
purpose.
The capital, yearly operation and maintenance and annual
cost for this method are estimated to be $55,000, $11,100 and
$19,300 respectively. Annual cost includes amortization of the
capital cost at 8% interest for 10 years.
Landfilling
Universally, this has been the most common method of solid
waste disposal. However, recently, regulatory controls on
disposal by landfilling have been instituted to make it an envi-
ronmentally sound practice. Various factors, such as hydrology,
geology, meteorology, groundwater and surface water use, and
land use of the area have to be considered for landfilling any
waste. Various control measures such as treatment and /or
confinement of the waste, confinement of the landfill site,
leachate treatment, etc. can be used to reduce the harmful effects
of the waste to the environment.
The waste in question is inorganic in nature and contains
metals along with salts which are 89% water soluble, ^solubili-
zation of these salts with chemical treatment was not consid-
ered a feasible alternative because of the high solubility of
sodium and potassium sulfates, which are the major constitu-
ents of the waste. This alternative, therefore, was not pursued
further.
Landfilling without chemical treatment was also investigated.
Non-existence of a chemical landfill, in the State of Connecticut,
which can handle this waste, restricted the investigation of this
alternative to the landfill owned by the municipality in which the
plant is located. Other out-of-town landfill sites were not
investigated due to transportation and organizational problems
involved.
The municipal landfill is operated by a private contractor
under contract with the City and acceptance of the waste at the
landfill is subject to approval by the State Regulatory Agency,
i.e. the Department of Environmental Protection (DEP). The
Hazardous Wastes Section of the Solid Waste Management
Unit and the Water Compliance Unit of DEP indicated that due
to the nature of the waste, some volume reduction measures
have to be implemented for ease of handling prior to disposal of
the waste at the municipal landfill. A pelletizer was considered
suitable for reducing the waste volume.
For the purpose of a preliminary evaluation, disposal of the
-------
36 Particulate Waste
waste at the landfill in plastic bags was considered. The capital
cost, yearly operation and maintenance, and annual costs for
this method was estimated to be $55,000, $3,400 and $11,600
respectively.
Even though some concern was expressed by the agency
regarding the heavy metals and salts in the waste, these
substances are not considered critical because the landfill is not
located adjacent to any water supply source. However, the State
would not grant approval to this disposal method on the
grounds of contamination of the surface water, essentially by
sodium sulfate.
Ocean/ River Disposal
Ocean dumping is regulated by the U.S. Environmental
Protection Agency (EPA) and is being discouraged. The
designated ocean dumping areas are remotely located from the
plant site and were not considered feasible disposal sites.
However, EPA regulations permit disposal at special sites
pursuant to a detailed study of the proposed dumping area as
well as study of other disposal alternatives. Also, a fee of S3,000
is charged by EPA for processing the application. The permit
granted by EPA may be limited to a certain period of time after
which the whole procedure would be repeated for renewal.
Therefore, this disposal alternative was not pursued further.
As the plant is located adjacent to the Thames River, the State
Regulatory Agency was requested to make a determination for
possible discharge of this waste to the river. This river is affected
by the tides in this reach and has a large volume of water. Thus,
the waste discharge would not noticeably affect the water
quality. Prior to its discharge, the waste would be dissolved in
water and the sediments would be removed for disposal at a
landfill. This procedure would remove most of the heavy metals
except nickel. The following effluent criteria was established by
the Regulatory Agency:
Chromium (Hexavalent)
Chromium (Total)
Copper 1 mg/1
Iron 1 mg/l
Magnesium 1 mg/1
Manganese 1 mg/1
Nickel I mg/1
Lead 1 mg/1
Zinc 1 mg /1
To satisfy the above criteria, it was estimated that
approximately 9,000 gallons of water would be required daily.
This quantity of water is needed to produce an effluent
containing 1 mg/1 of nickel.
The proposed quantity of water to attain the effluent criteria
was discussed with DEP which required that the water require-
ments for dissolving the waste be reduced by removing the
soluble nickel with chemical treatment. The DEP further
required to attain either an effluent containing less than 2 mg/1
of nickel using minimum practicable quantity of water or 98%
nickel removal.
A comprehensive laboratory study was carried out to deter-
mine the minimum practicable quantity of water for dissolving
the waste, the optimum pH for treatment, and the best chemicals
for removal of nickel. Visual observations indicated that 50 gm
of waste/ litre of water was the maximum solution concentration
attainable. Above this concentration, crystallization of the
solution took place. Another observation was that the pH of the
solution varies with the waste concentration. As the waste
concentration increases, the pH of the solution decreases. The
results of this observation are presented in Table II. It is
expected that pH of the proposed disposal solution without any
treatment would range between 7.5 and 8.5.
Polymers, soda ash, lime and caustic soda were used for
0.1 mg/1
1 mg/1
TABLE II: pH Variation with Solution Concentration
pH of the Waste Solution
5 gm/1
8.35
10 gm/1
8 .25
2 5 gm/1
8 .05
50 gro/l
7 .7
removing the nickel from the waste solution. As expected,
polymers alone were not effective in removing soluble nickel.
Preliminary tests showed that soda ash was less effective for
nickel removal compared to lime. Consequently, further testing
was carried out with lime and the results for 50 gm / litre solution
concentration are presented in I able 111.
This table shows that lime is not very effective below pH 9. At
a pH of 9, 84% nickel is removed after settling for 4 hours. The
results also show that filtering the settled sample through 10-15
micron filter does not increase nickel removal appreciably.
Higher lime dosage used in conjunction with polymers, would
be required to effect 98% removal. The dosage of lime required
to adjust the pH to 9 was4.75 gm/ 5gm of waste or almost one to
one ratio. Such large quantities of lime for treatment would
create sludge disposal problems. Therefore, further investiga-
tion with a higher dosage of lime was not carried out. Instead
caustic soda was used for further investigation. The results
obtained with a 50 gm of waste /litre solution are presented in
Table IV.
This table shows that caustic soda was effective around pH 11.
The quantity of caustic soda required to raise the pH of the
solution to 11 was about 30% of the total waste. In addition to
caustic soda, polymer would also be required to effect the
desired 98% removal. The pH of the treated effluent would have
to be adjusted with acid to around 9, prior to disposal to the
river. The settled solids would require dewatering prior to
landfilling. Since the caustic soda is expensive, another set of
tests was carried out by reducing the solution concentration
from 50 to 25 gm of waste/litre of water to determine if the
chemical cost can be reduced. The results of these tests are also
shown in Table IV, which show that there is no reduction in
chemical requirement. Therefore, it is more cost-effective to
TABLE III: Lime Treatment
Solution concentration = 50 gin of waste/litre
Total Nickel Cone. = 20 mg/1
Adjusted
PH
Sample
Type
Nickel cone.
After Settling
for 4 Hrs.
mg/1 .
» Removal
8
Settled
Filtered*
10.5
10.3
47.5
48. 5
8.5
Settled
Filtered*
8.3
7.7
58.5
61.5
9
Settled
Filtered*
3.2
3.0
84.0
85.0
*10-15 micron fritted glass filter used for filtratior
-------
Particulate Waste 37
TABLE IV: Caustic Soda Treatment
Solution Concentration = 50 gm of waste/litre
Nickel Concentration = 20 mg/1
treat the waste at a solution concentration of 50 gm of
waste/litre of water.
The capital, yearly operation and maintenance and annual
costs for three alternatives viz; dissolving the waste in 9,000
gallons of water and discharging the solution to the river;
dissolving the waste in 4,500 gallons of water and discharging
the solution to the river; dissolving the waste in 750 gallons of
water (about 50 gm/1), treating with caustic soda, polymers and
acid, and dewatering the sludge on a sand bed are as follows:
Capital
Alternative Cost
Dissolving in 9,000 $10,000
Gallons of Water
Dissolving in 4,500 $ 8,000
Gallons of Water
Dissolving in 750 $10,500
Gallons of Water and
Chemical Treatment
The above operation and maintenance costs include the costs
for monitoring the discharge, water costs at $1.40/1,000 gallons,
labor costs at $8/ hour and landfilling costs for the sludge.
Discussion
The capital, yearly operation and maintenance and annual
costs for three disposal methods viz; disposal by private
contractors, landfilling, ocean/river disposal are summarized in
Table V. A review of this table indicates that the most cost-
effective disposal method is dissolving the waste in 4,500 gallons
of water and discharging the effluent to the river and landfilling
the sediments. Due to large volumes of water in the receiving
river, the quality of the river would not be noticeably affected.
Also this method would involve the least use of resources. The
next choice would be to landfill the waste. However, the State
Regulatory Agency has some reservations concerning both of
these approaches.
The disposal method requiring chemical treatment would
need over 300 lbs. of lime or 90 lbs. of caustic soda daily to
remove about 0.07 lbs. of soluble nickel of a total of 0.1 lb. of
nickel. A considerable amount of resources would be required to
produce and transport these chemicals. As a result, these
chemicals may produce a greater adverse impact on the envi-
ronment than 0.07 lb. of nickel. Also, operation and
maintenance cost for this method is considerably more than
other methods. However, this disposal method is acceptable to
the Regulatory Agency.
SUMMARY AND CONCLUSIONS
The disposal of wastes generated by air pollution control
devices can cause a serious problem and should be planned when
the pollution control devices are being considered for
installation.
The study outlines various steps taken to define an econom-
RIVER DISPOSAL
COST
DISPOSAL
BY PRIVATE
CONTRACTORS
LANDFILLING
Dissolve in
9000 Gallons
of Water
Dissolve in
4500 Gallons
of Water
Dissolve in
750 Gallons
of Water +
Caustic Soda +
Polymers + Acid
Capital
$55,000
$55,000
$10,000
$8,000
$10,500
Yearly
O&M
$11,100
$ 3,400
$ 9,800
$ 7,500
$14,300
Annual
$19,300
$11,600
$11,300
$ 8,700
$15,900
NaOH Dosage
qm/qm of waste
Adjusted
PH
Nickel Cone.
After Settling
for 2 Hrs.
mq/1
% Removal
Soluble
Nickel Oonc.
mg/1
0.093
9
19.7
1.5
10.2
0.230
10
16.2
69.0
3.7
0.310
11
1.6
92.0
0.2
0.324
12
0.7
96.5
Solution Concentration
= 25 gm of waste/litre
Nickel Concentration =
10 mg/1
NaOH Dosage
qm/qm of Waste
Adjusted
PH
Nickel Cone.
After Settling
for 2 Hrs.
mq/1
% Removal
Soluble
Nickel Cone.
mq/1
0.115
9
8.6
14.0
0.288
10
1.6
84.0
—
0.317
11
1.6
84.0
0.1
0.360
12.3
1.4
86.0
Annual
O&M Cost Cost
$ 9,800 $11,300
$ 7,500 $ 8,700
$14,300 $15,900
TABLE V: Cost Comparison of Disposal Methods
-------
38 Particulate Waste
Alternative^
tap* — - „ ,
Cost Pi-" Cost-
D
Gallons of Water
Dissolving in 4,500
Gallons of Water
Dissolving in i50
Gallons of Water and
Chemical Treatment
— Annual
Capital Cost
lissolving in 9, 000 $10,000 5 9, 800 $11,300
$ 8,000 5 7 , 500 S 8,700'
$10,500 $14,300 $15,900
ical yet environmentally sound disposal method for a waste
generated by an electrostatic precipitator. This waste, 300 lbs. of
which is produced daily, is inorganic in nature and is 89% water
soluble. The major constituents are sodium sulfate, potassium
sulfate and boron oxide. Some heavy metals are also present
which are mostly in an insoluble form except nickei. Total daily
nickel content in the waste is about 0.1 lb. out of which 0.07 lb. is
water soluble.
Various disposal methods such as incineration, deep well
injection, on-site recovery of waste products, marketing the
waste as raw material, disposal hy private contractors, landfill-
ing (with and without chemical treatment) and ocean/river
disposal (with or without treatment) were considered. Only
disposal by private contractors, landfilling and ocean river
disposal were evaluated in detail.
The study concluded that chemical treatment was not
feasible. However, dissolving the waste in water, landfilling the
sediments and discharging the effluent to the river was the best
method available. The next economical method was landfilling
without treatment.
The disposal method utilizing chemical treatment and then
discharging the effluent to the river was acceptable to the
Regulatory Agency. This disposal method would require 750
gallons of water, over 300 lbs. of lime or 90 lbs. of caustic soda
daily to remove 0.07 lb. ol nickel.
During this study, it was experienced that in the absence of
well defined standards and guidelines by the regulatory
agencies, the development of an appropriate and cost-effective
solution to disposal of a waste could prove to be a costly and
time consuming undertaking lor the industry.
-------
Joint Incineration
of High Grease
and High Metal
Sludges from
Treatment of Municipal
and Industrial
Wastes—Detroit, Michigan
INTRODUCTION
The original Detroit Sewage Treatment Plant was con-
structed during the latter part of the Great Depression as a
Public Works Administration (PWA) project, and was placed
on stream in the Spring of 1940. Designed as a primary
treatment facility serving 1.7 million people (including con-
nected suburbs), it was located on 72 acres of land in Southwest
Detroit near the confluence of the Detroit and Rouge rivers. The
original plant included combined flow from homes, industry
and storm water from most areas.
Figure 1 shows the layout of the original plant in both plan
1 SLUDGE DIGES'IO* TANK
2 CAS HOLDER
3 ELUTRIATION TANK
4 CHEMICAL BIQG.
5 GO'LEH HOUSE
6 TIL TER BLDG.
7 INCINERATOR BlOG
8 MACHINE SHOP
9 STORE BOOM
10 SWITCH HOUSE
11 TRUCK SCALE
12 TRACK SCALE
• 3 CHLORlN A T ION BIDG
14 ADMINISTRATION B..0G
15 GARAGE
16 JUNCTION CHAMBER
JEFFERSON AVE
WEST
EFFLUENT
CONDUIT
>7 SURGE BASIN
18 POST chlorination CHAMB
19 SEWAGE PUMPING STATION
20 RACK a GRiT ChAMS. BLDG
21 CRiT CHAMBERS
22 URL' CHUORlNATION CHAMB
23 VENTuRi ME TERS
chlownat ion
Figure I: Detroit Wastewater Plant 1940-1968 Original Layout
and Processes
A. C. Davanzo
The Detroit Water and Sewerage
Department
Detroit, Michigan
and profile. Basically, the hydraulic flow was processed through
the six main lift pumps, each of which was followed by an
accompanying mechanically cleaned bar screen and twin
mechanically cleaned grit collector channels. The flow was then
distributed to the eight covered rectangular sedimentation tanks
which had a design capacity of 600 MGD. After moving across
the primary sedimentation tanks, the flow was collected in the
primary effluent conduit, chlorinated by the nine large chlorina-
tors, and returned to the Detroit River through an 18 foot
diameter, 6,000 foot long conduit. Treatment removal efficien-
cies were in the range of 30-33% for (BOD), and 50% for
Suspended Solids. At that time there were no phosphate, oil or
phenol standards, nor was there much concern about heavy
metals.
In the early years not all industrial plants were connected to
the sewerage system. For those industrial plants connected to
the system, pretreatment regulations were very minimal.
The solids removed by these various physical processes were
collected and disposed of as follows: The screenings were
ground up and returned to the plant influent going to the
primary tanks, since attempts to incinerate these screenings in
the multiple hearth furnaces were unsuccessful. Grit was either
incinerated or sluiced to the ash lagoons. Grease and scum
skimmed from the surface of the primary tanks was pumped
back to the incinerator building to be burned with the sludge
removed from the bottom of the primary tanks. The sludge was
first pumped to an anaerobic digestor. From the digestor, the
sludge was pumped to the elutriation tanks where it was washed
to remove alkalinity. The elutriation process was later aban-
doned and the tanks were used for sludge storage prior to
vacuum filtration.
As a conditioner to aid in the release of bound water, ferric
chloride and lime were added to the digested sludge before
processing it through the eight vacuum filters. After filtration,
the sludge cake was transported to the four multiple hearth
incinerators for final destruction. The remaining residue, having
been reduced to ash, was sluiced to lagoons. As an individual
lagoon was filled, it would be excavated under contract and the
ash would be taken to a landfill for final disposition.
The laboratory had little sophisticated equipment, since the
analysis required for primary operation was minimal. The total
original capital cost of this installation was some $22 million.
Expansion of the primary facility because of population
increases and further suburban demand was begun in 1952, with
two additional primary tanks placed in service in 1956. Growth
continued, and the present plant now occupies some 130 acres as
shown in plan by Figure 2. Figure 3 shows the current plant
processes in schematic profile.
39
-------
40 Joint Incineration
GREASE
INCINERATOR-i
electrical ay
\\ BLOWER
\\blogs
OXYGEN PLANT
-AERATION
. (UNDER*
r (
) final
7 )\ , VVclARIFIERS
OCp
m
fuMP STATION
3
legend
administration
bldg. a laboratory
FILTER 0 INCINERATION
BLDG.
POLYMER 8LDG-
PILOT PLANT
FERROUS CHLORIDE
SLUDGE THICKENING a STORAGE
PRIMARY SEDIMENTATION
INTERMEDIATE LIFT PUMPS
OAKAOOD 'NTERCEPTOR
jEFrERSON dpi interceptor
OUTFALL CONDUIT
Figure 2: Detroit Metro Wastewater Treatment Plant 1976
There have been major changes from the original installation
because of population increases and more stringent environ-
mental constraints. The plant is now three separate highly
complex operations serving 3,1 million people including the
total population of Detroit and 75 suburbs.
Expanded Primary Plant
The expanded primary plant now consists of eight main
pumps, each with its bar screens and twin grit channels, plus 12
rectangular and two circular primary sedimentation tanks with
a design capacity of 1,200 MGD. To increase treatment
efficiencies of both the solids process and nutrient removal, the
original primary plant has been converted into a physical-
chemical operation. Nutrient removals, especially phosphorus
are necessary to stem the further eutrophication of Lake Erie
Ferrous Chloride, waste pickle liquor from the hydrochloric
acid used to wash steel during the manufacturing process, is
trucked to the plant on nearly an around-the-clock basis and
stored in rubber lined tanks. This acid, some 50,000 gallons per
day on the average, is fed through glass lined pumps into both
interceptors to guarantee mixing with the incoming wastewater
as it is lifted by the main pumps. Anionic polymer is also added
to increase settling characteristics of the solids.
The hydraulic flow, as before, passes through the bar screens,
but the material is no longer ground up for re-deposition in the
process flow. The screenings are now transferred to containers
for ultimate disposal at sanitary landfill sites.
The grit removed is still handled as originally designed, either
DETROIT RIVER
being burned in the six multiple hearth furnaces in Incinerator
Building No. 1, or is sluiced to the ash lagoons. Before the flow
enters the primary tanks, an anionic polymer is added. This is a
polyelectrolyte of which, on the average, some 1200-1600
pounds per day is added to the process stream. The polymer is a
coagulant which helps to increase the efficiency of the primary
sedimentation tanks. BOD removal efficiencies increased to the
50% range, and the suspended solids removals have been
increased to the 65% range. Phosphorus removals in this system
are at best, are around 55%; and of course, the increased
removals from all of these operations translates into an
increased solids load. The sludge from the primary system,
which average 8% solids, is now pumped to the sludge thicken-
ing, blending, and storage facilities for further processing,
Anerobic digestion was dropped as a treatment process because
of the difficulty of operation which was in part due to the lack of
industrial pretreatment standards in the earlier years.
Grease, scum, and other floatables are skimmed from the top
of the primary tanks. This material is mechanically collected,
processed through grinders, and pumped to a decant tank. The
concentrated material is then fed into a specially designed water
hearth incinerator for final disposal. Additional industrial oily
wastes are also received by trucks for disposal in this facility.
Because of the predominance of metal working industries in the
service area, this plant probably receives more grease and oil per
gallon of flow than any other plant in the world.
Facilities Plans call for the addition of two more circular
primary tanks (300 MGD) in the near future and possibly two
-------
Joint Incineration 41
A. PRIMARY TREATMENT PLANT
TO PLANT
PROCESS WATER
SYSTEM
/
nLU Ml riMI lyn I
f©> f®t
TO RIVER
WASTE ACTIVATED
SLUDGE TO SLUDOE
PROCESSING
B. SECONDARY TREATMENT PLANT
Figure 3: Detroit's Wastewater Treatment Process
-------
42 Joint Incineration
more circular primaries at a later date to an ultimate 1800 MGD
primary capacity.
Secondary Treatment Plant
The current 450 MGD of primary effluent going to the sec-
ondary portion of the plant, again, has to be hydraulically lifted
before entering into the biological treatment process. This
means intermediate pumping is required. In addition to the two
variable speed (150-300 MGD) lift pumps, the secondary plant
currently consists of two aeration basins, nine circular sec-
ondary clarifiers, each with a 25 MGD return sludge pumping
station, and a chlorine contact conduit with 4 chlorination feed
points. To provide the aeration, there are two 7,000 HP
compressed air blowers and a 180 ton/day cryogenic oxygen
generation plant. There are also two additional pump stations.
One used to move waste sludge and one used to provide treated
flow to the process water system.
t he process flow is divided into two streams; one undergoing
air aeration (150 MGD), and the other receiving pure oxygen
aeration (300 MGD). The oxygen basin which is covered, also
requires additional mechanical mixing. This is currently the
largest such installation in the world. Under construction are
two additional oxygen aeration basins (300 MGD, each), 12
circular secondary clarifiers, three additional lift pumps to serve
this portion of the system, and a 400 ton/day cryogenic oxygen
generation plant. Also to beadded are more waste sludge pumps
and more process water pumps. In the design stage for the near
future are four more clarifiers. Plans ultimately call for the
conversion of the 150 MGD air aeration basin to an oxygen
operation to enlarge its treatment capacity to 300 MGD, giving
the total secondary system a final size of 1,200 MGD.
Secondary removal rates approach 90%, and a biological
sludge of very thin consistency is generated and settled out in the
peripheral inflow/peripheral discharge high overflow rate
clarifiers. Grease skimmed from the final clarifiers is recircu-
lated through the drain system back to the head end of the plant.
Because of the use of oxygen, it is important to remove as much
grease as possible in the primary plant since there are
hydrocarbon alarms on the UNOX aeration basin.
The clarified flow from the secondary system is chlorinated;
and at present, blended with the stream from the primary
operation and returned to the Detroit River. Some secondary
flow, approximately 40 MGD, is used as process water in some
parts of the plant and is pumped from the treated flow before
blending. As noted, this water is used throughout the plant, but
especially in the solids disposal operation as cooling water in the
incinerator air pollution control scrubbers.
Solids Processing, Handling & Disposal Facilities
Both the primary and secondary operations generate tons of
liquid sludge which must be disposed of before the treatment
process is completed. This requires the services of the plant's
third operational area; solids processing, handling, and dispo-
sal.
Solids disposal is both expanded and more complex when
compared to the original solids disposal installation. In addition
to the increased loads, the biological sludge is very thin, around
1% solids, and must be concentrated for more economical
processing. This 1 % sludge readily thickens to 4% in the plant's 6
gravity thickeners.
Thickened sludge is then blended with the primary sludge and
placed in storage tanks to await further concentration by
vacuum filtration. Additional thickening, blending, and storage
facilities are either under construction or planned for the near
future.
After preliminary preparation, the sludge then enters one of
the three filter rooms where there are now a total of 28 vacuum
filters. C'ationic polymer is used exclusively as a conditioner to
aid in sludge dewatering since it is less expensive than the ferric
chloride and lime combination which also added a considerable
amount of additional solids to the incineration load.
Alter filtration, the sludge is conveyed to the 14 multiple
hearth incinerators. All units arc equipped with air pollution
control devices. The resultant ash is discharged dry through a
vacuum system into five .storage silos from where the material,
over 200 tons per day, is trucked to landfill sites for final
disposal. A set ash sluicing system, with its lagoons, serves only
as a backup to the dry ash operation. Awaitingconstruction are
20 additional filters and eight more incinerators.
Because of inflationary factors, capital cost comparisons are
impossible. To date, since 1966, which is after the Lake Erie En-
forcement Conferences and when planning began for the current
expansion, some $200 million has been invested in the plant
alone, exclusive of interceptor expansion.
For this presentation we want to specifically zero in on grease
disposal and the incineration of sludges containing heavy metal
loadings.
As originally designed, the rectangular primary tanks
skimmed the grease at the discharge end of the units by means of
mechanical cross collector into vats from whence the material
was repumped using screw poller units to a decant tank located
in the basement of the sludge incineration building. The original
design intention was to distribute the decanted grease onto the
dewatered sludge cake as it passed by on the conveyor system
and thence on into the multiple hearth incinerators. This system
was not successful. The grease addition created problems with
incinerator operations. Multiple hearth incinerators used for
municipal sludge disposal were originally designed for ore
smelting. These units have three distinct /ones of operation; a)
drying, b) combustion, and c) cooling. In the 11/12 hearth units
at Detroit, the first three hearths were intended for drying the
incoming sludge through the use ol the hot gasses from the lower
combustion /one. The grease addition on the incoming sludge
cake caused pre-ignition leading to excessive smoking and
slagging problems as well as fire brick damage due to hot spots.
The grease feed problem was finally solved by injecting the
grease directly into the burning hearths. This was done using
small diameter pipes since the grease removed was as such vol-
ume that it floated enough inorganic grit that it could not be fed
through a burner orifice.
This procedure was followed for many years but unfortu-
nately the system was not able to burn all the grease that was
collectable, nor was the collection system itself reliable. Little at-
tention was paid to the problem in the early years since Detroit
was deeply involved in the war effort and effluent standards as
we know them today did not exist. Records show that average
incoming grease loads were in the range of 100 mg/ L which
translated into large volumes for a plant that currently averages
nearly 900 MGD. The average flow some 25 years ago had
already reached some 400 MGD which would yield over 300,000
pounds of grease and scum per day if it all could have been
removed. Current loads are in the range of 700,000 pounds per
day.
In the early 1960's, the spectre of a dying Lake Erie was raised
and Congress convened hearings concerned with the pollution
of the Lake and its tributaries. As a result of these hearings,
Detroit signed a stipulation with the Michigan Water Re-
sources Commission foreffluentlimitationswhichincludeda 15
mg/1 limitation on grease discharges. Detroit developed a
master plan based on a regional treatment system and we have
been proceeding toward compliance in the intervening years.
As part of this program, Detroit mounted an assault on grease
problems in three major areas. An Industrial Waste Group was
formed to work with industry in an attempt to reduce the
amounts of grease being discharged into the sewerage system. A
-------
Joint Incineration 43
copy of our current Industrial Waste Ordinance is attached to
this paper.
In 1969, a redesign of the rectangular tank grease collection
system was started and design was begun of a special grease
incinerator which would be able to dispose of all the grease
collected. At the same time, additional primary tank capacity
was being designed. These new tanks were to be circular and to
have a completely different collection system as opposed to the
rectangular units. This paper would have a short and happy
ending if we could report that everything worked and the grease
problem was resolved. Unfortunately, the grease collection and
disposal problem is very involved and solutions do not come
easy.
First the redesigned system for the rectangular tanks attemp-
ted to rectify the two major problems encountered on the
original installation; that is the flooding of the grease vaults
during storm flows and the difficulty encountered in pumping
grease, especially in winter weather.
It was decided to have the grease cross collectors to traverse
an apron at the effluent end of the tanks and to ramp up before
discharging into hoppers from whence the material would be
repumped. It was intended that hot water would be added to the
material in the hopper from where this mixture would pass
through a disintegrator and be pumped through an open
impeller type pump into special insulated piping to a decant tank
in the new grease incinerator building.
This was strictly a mechanical collection approach with after
many difficulties has begun to function quite well. In order to
have the collected grease level up a 30° inclined ramp some 15
feet long each skimmer was designed with a torsion bar to take
up the stresses. As a further concession to plant maintenance
problems the system was built with stainless steel nuts and bolts.
As the chain driven flights proceeded up the ramp, many of the
nuts and bolts vibrated loose and were dropped into the hoppers
along with the grease. The disintegrators were designed to
process grease and other floatable scum but were not designed to
chop up stainless steel nuts and bolts. The torsion bars on the
collection flights originally were conceived as being readily
available units as used on a small imported automobile turned
out to be custom made, raising the cost of each flight to $800.00.
With 12 tanks and 54 flights per tank, their failure immediately
became a major concern.
The loose nut and bolt problem was first addressed by peening
the bolt ends to stop them from vibrating loose. Finally, the
plant staff replaced all the stainless nuts and bolts with cadmium
plated units which rust into place and hold. The flights were
resigned to function with multiple pieces of rubber and without
the torsion bars. The grinder plates with three small round holes
were exchanged for units with a tear drop shape which allows
some passage of little bits of ungrindable material. The open
impeller pumps and the insulated piping with a hot water line
enclosed in the same jacket were not a problem.
Other than the somewhat unreliable hot water system, grease
collection by this mechanical means has become acceptable
although it does require high levels of maintenance.
On the large (250' dia.) circular tanks, the grease collection
system as designed proved to be too complicated to be operable.
Each pass of the skimmers were to pickup some 200 gallons of
primary effluent, floatable oil and scum. These 200 gallons were
to pass through a comminutor into a scum pit. There, a mixer
would emulsify the mixture the addition of hot water as
required. This emulsified mixture would then be repumped to
the decant tank in the scum incinerator.
This system was to operate intermittently as the skimmer
made contact with the beaching ramp. At this time, the
comminutor was to switch on, valves were to open, mixers were
to mix, etc. The system violated all rules of the KISS (Keep it
simple, stupid) doctrine. Mid winter operations proved nearly
impossible as the grease froze in large gobs at the edge of the
beaching ramp. Small bits of plastic from feminine hygiene
products fouled the comminutors. Modifications to this collec-
tion system are still underway, so total grease collection at
Detroit is currently dependent upon the rectangulartank system
previously described.
Once the collected material arrives at the Scum Incineration
facility, it is discharged into two large (5,000 cu. ft.) decant
tanks. The grease is skimmed from the top into chutes from
where it is pumped into the water hearth incinerator. The theo-
ry of operation says that as the grease and oil floats to the
surface, the heat from the three burners around the 14 foot
diameter fire pot will allow the volatiles to rise, enter the
combustion chamber, burn, with the exhaust gases passing
through a three stage impingement tray scrubber.
These grease incinerators were to be the ultimate solution to
grease disposal, but as usual, paper designs seldom function in
practice without significant modifications. In this paper and in
almost all conversation of the subject, we refer to grease, scum
floating oil, etc., as interchangeable words. In combined
municipal/industrial wastewaters where there are sufficient
grease loadings, there emerges a hybrid combination of
floatable materials that includes a percentage of small sized
inorganic grit particles which are carried along by the floating
greases along with bits of plastic, cigarette filter tips and so on.
We therefore envision oil or grease on water but are confronted
with a completely different material that is much more compli-
cated to process.
If we are collecting and burning floating oil, all systems would
probably work. The problems with burning the material
collected has proved more difficult.
For instance, water hearth incinerator was not designed for
much cleaning at the bottom of the fire pot but as the grease
laden material was heated to lift off the volatiles, the inorganic
particles now released from floatation collars settled. It became
necessary to operate intermittently rather than continuously.
Four days of burning, one day of cooling, one day of grit
removal, one day to heat back up to burning temperatures. This
is not the best way to operate an incinerator, but in this mode the
job is being done successfully.
This strange hybrid material caused other incinerator control
problems. The liquid level in fire pot is controlled by an
adjustable elbow discharging into a tank connected to drain.
This assumes that the level in the fire pot is equal to the level out
of the pipe and if all was liquid this would be true. But with this
material, solid floating layers 3-4, inches thick have been
observed. These thicknesses of crusty material were not antici-
pated in the original design. Level control; therefore, becomes
most important so that the fire brick which starts just above the
assumed water surface is not damaged during operation.
There were installed in the original installation, rotating
breaker bars to break up this floating crust. These breakers
proved to be ineffective and lead to a major operational
problem. Feed rates were coupled to a temperature sensor but
when the crust layer formed, temperatures dropped since
volatiles were not being released and burned. With the tempera-
ture drop feed pumps cycled on, but as long as the crust layer
wasn't broken, the temperatures would not rise. It was possible
to fill the whole fire pot with grease and grit without burning.
There were also some problems with an improperly sized
primary air fan.
Modifications including a method for injecting air at the time
when the feed pump cycles on have solved the crusting problem
and improved operations. Out of adversity, many times comes
some unexpected benefits. The inorganic grit which falls to the
bottom of the fire pot still has small amounts of grease attached.
In a large plant where large stop logs are used to isolate units for
maintenance (since large sluice gates are too expensive), sealing
-------
44 Joint Incineration
problems develop. By adding some of (his magic material to the
upstream side of the logs it will be carried by the flow into the
small leaking crevices and yield a good seal.
In recapping this short discussion on grease burning, we
mentioned the problems of trying to dispose of heavy grease
loads in multiple hearth incinerators, the development of
reasonably reliable grease collection equipment, a discussion of
what a combined sewerage system yields in the way of greasy
material, and how this material is finally treated.
Two other short notes about grease. Although we designed
this system to accept some directly trucked industrial oily
wastes, little has arrived since the energy crisis had made this
material too valuable to burn. We have received materials
cleaned up from some oil spills into local waterways. Some of
the spills were from sewerage systems.
In the matter of reclamation, there is now some research
underway on the possible reuse of at least part of this material.
When extracted, a heavy oil in the range of No. 6 fuel oil
emerges. Development of new type burner is also being
investigated so that this material would not have to be as clean as
the oil must be for presently used burner units.
The amounts of grease and oil may sound large, but are in
reality small when compared to the thousands of wet tons of
sludge which must be incinerated daily at Detroit. Although
some greases and oils become entrapped in the sludge, the per-
cent volatile material is about average in primary sludge (50%),
but somewhat below average in secondary (60-65% vs. 70-85%).
This may be due to the fact that the incoming BOD load to this
plant is relatively low, in the range of 140 mg/1 while COD
loadings are higher than average.
The plant primary tanks, rectangular and circular were de-
scribed in the discussion on grease. This plant being located on
the Great Lakes must also practice phosphorus removal. For
this purpose chemical addition is practiced consisting of ferrous
chloride and anionic polymer addition into the primary system.
Since the construction of secondary treatment facilities were not
begun until 1970 and since the first effluent standards were for
soluble phosphorus, the chemical addition effort was placed in
the primary plant. New standards are for 1 mg/1 total
phosphorus in the effluent and new research is underway.
Currently, because of some mechanical problems with our
oxygen aeration (UNOX) system, approximately one-fourth of
the total plant influent, some 200 MGD, is receiving secondary
high rate activated sludge treatment. Therefore, blended sludges
are predominately from the primary treatment process. More
waste activated sludge is routed to Filter Complex II via the
gravity thickeners.
Table I shows metal analyses of raw sludge for 5 recent non-
consecutive days in mg/1.
COMPLKX
11
2/1
n
().'>
1657
74074
UH'f
2222
76
3255
2/7
i
3.3
340
8<)000
920
1340
460
2880
3/10
ii
6.0
2150
78000
1250
1740
88
3670
2/21
ii
7.2
1530
56700
1080
1890
66
3180
2/22
ii
7.6
14600
76000
820
1020
50
2800
In Detroit, raw sludge with cationic polymer as a conditioner
is processed through vacuum belt filters yielding a cake in the
range of 25 to 28% solids. I his cake is transported via a mileand
a half of conveyors to the multiple hearth incinerators.
The cake is not quite dry enough for autogenous combustion
so natural gas is used as a makeup fuel with No. 2 fuel oil as a
backup. The incinerator units are either 11 or 12 hearth units
dependent upon which complex we are discussing. All sludge
must be incinerated since there arc no alternative disposal
methods. Ash from the incinerators is normally extracted dry
and transported to silos for temporary storage from whence it is
hauled to landfill. There is little public opposition to the burial
of inert ash although some concern has been expressed about
possible heavy metal leachate into ground water supplies. As a
backup, ash can be mixed with final effluent and be transported
via sluicing pumps to lagoons for longer time storage. This
material is excavated when the lagoons fill and like the dry ash
hauled to landfill.
There is no real average ash sample but Table II shows recent
metal analyses based on the dry weight of ash. Unitsare mg/kg.
You will note the high amounts of iron in the sludge and ash
analyses due to ferrous chloride addition. This amount of iron
does contribute to some of the slagging problems experienced in
incineration. Most other metals present no incineration prob-
lems and most of the metal content of the sludge passes into the
ash with little loss to the atmosphere.
Table II
Based on dry wt. of ash mg/kg
Aluminum
22,000
Copper
Magnesium
12,000
Iron
Barium
1,200
Lead
Sodium
1,500
Manganese
Calcium
55,200
Mercury
Cadmium
51
Nickle
Cromium
2,000
Zinc
Cobald
38
Arsenic
1.500,
66,000]
17,000i
1.5001
0.1
1,600
3,600
9
Table I
COMPLEX
I
FILTER
COMPLEX
% SOLIDS
Cr
Fe
Cu
Ni
Cd
Zn
2/1
I
4.9
1673
70079
1260
2283
77
3484
2/7
I
5.9
1650
70900
1080
1720
560
3360
2/10
I
5.4
2200
91600
1220
1800
124
3540
2/21
I
7.0
2160
54900
1230
2280
63
3600
2/22
I
6.1
14200
65000
900
12200
40
2940
Currently, the only emission standard for metals from
stationary sources is for mercury and we are well within
compliance limits.
The Detroit system is an example where joint
municipal /industrial treatment has been successful. Whether
this cooperative effort can continue is dependent upon what
future course EPA charts as far as Industrial Pretreatment
Standards. The metal working industry and especially the
plating shops have cooperated with the Detroit Department of
Water and Sewerage in controlling heavy metal discharges. Few
problems with heavy metals have been encountered since the
biological treatment facilities were placed on line 2 'A years ago.
It is hoped that future problems concerning standards and
Industrial Cost Recovery charges can be worked out to every-
one's mutual satisfaction.
-------
Joint Incineration 45
The Detroit Water and Sewerage Department collects and treats
the wastewater of southeastern Michigan communities located in
Wayne, Oakland, and Macomb counties. The plant treats flow
from residential, commercial and industrial sources as well as
storm water from Detroit and some of the adjacent suburbs.
1. The wastewater flow to the plant, from the region, can
exceed 1,200,000,000 gallons per day. The average flow
is 800 MGD (million gallons per day) and is ever
increasing. The wastewater arrives at the plant via two
large gravity interceptor sewers, 12' and 16' in diameter.
A third major interceptor is under construction, while a
fourth is being planned.
2. At this point, minute quantities of ferrous chloride are
injected into the wastewater which binds up most of the
phosphates into a settleable form. The State requires the
removal of 80% of all phosphorous.
3. Eight huge pumps lift the wastewater nearly 40 feet
allowing it to flow through the primary portion of the
plant by gravity.
4. Bar screens capture most rags, sticks, strips of plastic and
other coarse material which are automatically removed.
The material is dropped onto a conveyor which deposits
it In containers for later removal to a sanitary landfill.
5. Long narrow grit chambers cause the wastewater to slow
down, and drop heavier material such as sand, glass,
bottle caps, egg shells and coffee grounds to the bottom.
This material is also removed to a landfill.
6. A synthetic chemical (polyelectrolyte or polymer) is
added to aid coagulating and settling suspended particles
in the primary clarifiers.
7. Primary clarification (both rectangular and circular tanks
are used): As the wastewater makes its one-hour journey
through the primary clarifiers (sedimentation tanks)
approximately 50% of the organic matter settles to the
bottom as sludge, and is removed. At the same time oils,
greases and other floatable materials are skimmed from
the surface. These items are handled in steps 16 and 17.
8. The flow from the primary portion of the plant is
collected and transported by tunnel to the advanced
treatment portion of the plant. Here two large variable
speed pumps lift the flow some 25 feet so that It may
complete the remainder of its journey, by gravity, to the
river.
9. At present two similar activated sludge processes are
being used. One is the standard method where air is
bubbled through the primary effluent allowing certain
naturally occurring bacteria to consume most of the
remaining organic material. The activated sludge tanks
are twice as deep as normal to preserve land and save on
construction cost*.
10. Huge blowers compress and transport the air required in
the standard activated sludge process.
11. The second activated sludge tank is covered and employs
the use of pure oxygen, and is able to handle twice the
flow of the standard tank in the same time period. If this
new oxygenation process proves to be more economical,
as is expected, the first tank will be converted in the
future.
12. A cryogenic process oxygen plant produces all of the
oxygen consumed each day as well as a small excess of
liquid oxygen which is stored for standby use.
13. The wastewater now enters the specially designed (and
patented) peripheral inflow and discharge secondary
clarifiers where most of the scavenger bacteria settle out
as sludge. A portion of this sludge is returned to the
activated sludge banks to keep up the bacterial
population, while the remainder is disposed of as
explained in step 17. The nearly pure reclaimed water
flows over the top of the weirs to the chlorine contact
chamber.
14. The treated effluent is now dosed with chlorine to assure
that practically all bacteria is killed. The renewed water
now meets swimming beach quality. This flow rejoins the
river and is dispersed. The flow in the river is at least
100 times greater than the flow from the plant.
15. A portion of the treated flow is extracted for use as plant
process as required in steps 16, 17 and 19.
16.The scum from the primary clarifiers is burned in a
specially constructed water-hearth furnace at 2000®F.
The air pollution control equipment uses processed
water which is returned to the interceptor.
17. The waste activated sludge from the secondary clarifiers
is transported to the gravity thickeners, thickened and
blended with primary sludge and then stored before
being further processed.
18. The blended sludge is now dewatered using large rotary
vacuum filters. The material extracted from these filters,
referred to as sludge cake, is dropped onto conveyors.
19. The sludge cake is transported by conveyor to the top of
the world's largest municipal multiple hearth furnaces
and incinerated. Detroit was one of the nation's first
communities to add air pollution control equipment to
its incinerators. This equipment alio uses reclaimed
processed water.
20. The ash, which is the inert residua of the material
removed from the wastewater, is transported to a landfill
for burial which completes the wastewater treatment
process.
-------
46 Joint Incineration
ORDINANCE NO. I29-H
CHAPTER SO
. autici.u e
UIKJULATii IHSCIMKGK OF
INDUSTRIAL OH COMMERCIAL
1VASTK INTO WASTEWATER
THKATMKNT SYKTKM Or CITY
OF DKTROIT
AN ORDINANCE to amend Chapter 56
of I lie Code of the City of Detroit
by rrculliijf u new article, to lie
known iis Article U, which regnliitrs
tlii! itl.irliarge or Industrial or com-
n.irclul waste Into (be wastewater
iniuiiicnt system of the City ol De-
troll. Tills ordlmiiue la designed to
fotilltaie the treatment of indus-
trial waste discharged to (lie sew-
ers. The Intent Is to require the
minimum presentment from In-
dustry and perform nt a central
treatment plant all cleanup of the
wastewater which can beat be per-
formed there.
IT 13 HEREBY ORDAINED BT THE
PEOPLE OP THE CITY OP DETROIT:
Section 1. That Chapter Be of the
Code of the City of Detroit be
amended by creating a new article, to
bo known a* Article A, to road a*
1'oUowa:
Svc. 5(5-0-1. By virtus ot obligation*
and authority placed upon the Board
of Water Commissioners of the City
of Detroit by the Federal Water Pol-
lution Control Act of 1972,-the State
of Michigan Act 245 of 1030, as
amended, and the National Pollution
Dltchargc I'Minlrwitfon System Permit
No. MI U022U03, or by virtue of court
orders. Minting or future contracts
between the Board of Water Com-
missioners of the City of Detroit and
suburban communities, or by virtu*
of common law usage of the system,
these regulations shall apply to every
InUvati'ial and commercial user whose
wastewater Is treated at a treatment
I-laut of the Hoard of Water Oom-
mlsr.ioiioru of the Olty of Detroit.
68-fl-tf. "Hoard" all all nieau Board
of Water Commissioners of the Olty
of Detroit.
Sec. 88-6-3. "The Director" shall
mean the Director of the Department
of Water and Sewerage of tha Olty of
Detroit or his deputy or hie desig-
nated representative.
Boo. 80-6-4. "Chief Engineer" shall
mean the Chief Engineer of the Board
or his authorised professional engi-
neering representative.
Bee. 60-8-6. "Industrial Waste"
ahull mean any liquid, solid or gaa-
eoua vvuute or form of energy or com-
bination thereof rei?ul(ing from any
proceaa of Industry, manufacturing,
buulntss, trtida or teticurch, Including
tho development, recovery or process-
us of natural resource*.
See. 66- 0-0. "Compatible wiurte"
shall mean BOD, suspended solid*,
oil, grease: (hexane solubles) and
phenollo compounds.
See. 83-0-7. "BOD" (denoting bi-
ochemical oxygen demand) shall
moan the quantity of oxygen utilised
In the biochemical oxidation of or-
ganic matter under standard
laboratory procedure In five days at
20*0., expressed to milligrams pw
liter (mg/1).
Sec. 60-8-u. "Grease" in wa»towat#r
shall mean a group of substance*. In-
cluding fats, waxes, free fatty acids,
calcium and magnesium soap*,
mineral oils, and certain other noa-
(atty materials. The type of solvent
and method used for extraction shall
be that specified In "Standard
Methods for the Examination of
Water and Wastewater."
Sec. 00-0-0. "Phenollo Compounds"
shall mean hydroxy derivative* of
bensene a* described la "Standard
Method* of Waste Wader Analysis".
Sec. 60-0-10. "Suspended Solid*"
shall meau solid* that either float on
the surface of, or ore In suspension in
water, sewage or other liquid*; and
which, in accordance with Standard
Method*, are removable by laboratory
filtering.
Sec. 60-0-11. "Properly Shredded
Garbage" ahaU mean the waste from
the preparation, cooking and dispens-
ing of food that ha* been shredded to
such degree that all particle* will be
carried freely under the flow con-
ditions normally prevailing In public
sewers, with no particle greater than
one-half inch In any dimension.
Sec. 66-8-12. "pH" shall mean the
logarithm of the reciprocal of the
weight of hydrogen Ion* in gram* per
liter of solution.
Bee. 66-0-13. "Publlo Sewer" shall
mean a common sewer controlled by
a governmental agenoy or pubUo
utility.
Sec. 68-0-14. "Sanitary Sewage"
shall mean wastewater discharged
from the sanitary conveniences of
dwellings and other buildings and
places In which sanitary convenience*
are used or installed.
Boo. 60-6-10. "Wastewater Plant"
¦hall mean anv Board-owned facility,
device* and stiucture* used for re-
ceiving and treating sewag*.
Seo. 60-0-10. "Service Area" shall
Include any area whose wastewater
Is treated at' a wastewater plant of
the Board.
Seo. 60-0-17. "Standard Methods"
shall mean the laboratory procedure*
set forth In the latest edition, at the
tlmo of analysis, of "Standard Meth-
ods for the Examination of Water
and Wastewater," a* prepared, ap-
proved and published Jointly by the
American Public Health Association,
the Ainerlcan Water Works Associa-
tion and the Water Pollution Contrdl
Federation, or methods acceptable to
tho U. 8. Environmental Protection
Agency.
Sec. 6U-0-10. "Wastewater" shall
mean a combination of the witter mid
water-carried wastes from buildings
and facilities plus uorntally collected
itormwater.
Seo. 60-0-10. The Director, as the
duly authorized agent of the Board,
shall be responsible for the investi-
gation, smnpllng, monitoring and
other work necer,6ary for the enforce-
ment of this ordlnnnce.
See. 66-0-20. Any wnste will be
considered deleterious (and prohibit-
ed) that may cause damaging «ffeoU,
a* stated under Bee. 60-0-31, or does
not conform to the limitation* *tat*d
under specific chemical pollutant*.
See. 60-0-31. Dnmaclng effects not
otherwise described:
A) Chemical reactions, cither di-
rectly or Indirectly, with the material
of construction to Impair the
strength or durability of fewer
structures and/or appurtenance*.
II) Mechanical action that will de-
stroy or damage the sewer structure*
nnd/or appurtenances.
Ci Restriction nt tlio hydraulic ca-
pacity of sewer structures nnd/or np-
purtciianccH.
i>) Restriction of the normal In-
spection or maintenance of tho sewer
structures nnd/or nppmtennnces.
IE) Placing of untmial drntnnd* on
lh* wastewater treatment equipment
or procct.tf.
F) LI nilliitlon of the elfectlvenena
o( the wastewater treatment process.
0) Dungcr to public health *ud
safely.
Ill Obnoxious conditions Inimical
to tiie public Interpol.
1) Contains substances that ar*
deemed harmful to receiving wa-
ters and do not lend themselves to
destruction or removal In th* waste-
water plant.
Sec. 60-0-23. Compatible waste*
Which are discharged by Industry In
concentrations greatly In ex cess ot
domestic sewage will be sampled,
analyzed and treated at cost* to be
horn by tho permittee. No costs shall
be assessed unloia the concentrations
are greater thnn those found below:
Waste Cimrenlrntlon
A) Suspended Unlldj COO mg/1
B) HOD 300 "
C) Hcxnne Soluble (Total
Orenne) In supernatant
liquid after lour hours'
settling 100 " *
D) Floating Oil None collectible
E) Phenolic compounds 0.6 ing/l
F) Total OolWs 3,000 mg/1
(Dally Average)
30.000 m*/l
(Anv Sample)
Sec. CO-fl-23. Mmlls of specific
ciictuU.il pollutunit lor discharge to
lowers:
Soluble Incompatible
I'oKuUnU Liint!*
A) Antimony 9.0 mg/1
B) Arsenic 10 "
U) Cadmium 3.0 "
D) Chromium. Hen-
valent (Cr+M 5.0 "
E) Chromium (Total) 25,0 "
F) Copper 3.0 "
G) Cyanide (Total) 3.0 "
II) Iron 60.0 mg/l
I) Lead 10 "
if) Mercury 0 000 "
JC) NtcVel » 0 "
I.) Phosphorus 110 "
M) Polychlorlnated
niplienyla 100 parts per trillion
If) Beienluin 1.0 mg/1
Soluble Incompatible LlmtU
pollutant*
0) BlWer 3.0 mg/i
p) Sulfides 10.0 "
Q) Thallium 0.1 "
R) Kino 110 "
13) nan, 003, NO (Total) 10.0 "
'1') Exploitive Substances
Ui Combustibles None detectable
V) Radioactive Wanle 100 uc/1
W)Toxlo Ousos Nolle detcctable(i)
Uetitrni Con JlUims Umlt*
1) Orcnrfo or Oil that wilt eoltdlfy or
become viscous at 60* P or above
None detectable
3) Limitation on Fartlcl* tllze
Must piuss a slev*
(%" In an/ dimension)
9) Limitation on Upcclno Oravlty or
Buupendcd Qolld.i 3.05 Maximum
-------
Joint Incineration 47
4) Temperature Limit 180* F
6) anoxic or Irritating flubetances (not
otherwise described)
Mono detectable (1)
0) pit 6.8 to 10.5
Gcc. 60-0-34. If any water* or
wastes are dlachorgcd, or are piopo/ied
to b« discharged, to the nubile sewers,
whlcli may cause damaging eiiects. M
listed under Beo. 60-0-31 herein, or
contain an excess of the substances
or exceed the limitations, enumerated
In Section 60-8-23 of this Article, or
which otherwise create a hazard to
life or constitute a. publlo nulsnnce,
the Director, aa the duly authorized
agent of the Board, may under the
provisions of Beo. 68-8-31:
A) ncject the waste to Immediately
abate euch hazard or publlo nuisance
°r
/I) llequSrc prttrtnlmcr.t of Incoiu-
pntlble wosla to un accpptnUe con-
ultlon for discharge to the public
sewers and/or
C) Require periodic reports on efTlu-
ent volume nnd quality ntid/or
f.) Require control over tho ouantl-
ties and rates of discharge and/or
E) Assess aud collect surcharges to
cover the ndded cost of handling and
treating the over-ltmlb discharge of
compatible waste and assess monitor-
ing and surveillance fees when the
limits of litcomptillbld wastea, oe do-
ll tuil in this ordinance, are found to
be exceeded. Bilcli surcharges shall be
unlfoim throughout the syotem nnd
In accordance with a schedule to be
published whenever conditions require
updating, such surcharges shall be
applicable on the basis of samples
taken at the control manholo (or Its
equivalent) of each industrial and
commercial user.
(1) If the waste meets the United
States Occupational and Health
Agency standards, a* described in
subpart a—"Occupational Health
and Environmental Control", It
shall be deemed to be free of
these gases or substances.
If the Director requires the pre-
trciUrruMit of Industrial waste flows,
the design arid Installation of the
pretreatnient plants and equipment
shall be subject to the revlow and
approval of the Hoard's Chief Engi-
neer and subject to the requirement
of all applicable codes, ordinances and
laws.
Bee. 80-0-38. The Hoard, acting
through the Director, shall have the
authority to schedule hearings and to
make changes, additions or deletions
to the foregoing limitations with due
notice to affected Industrial or com-
mercial users In the serrlce area of
the Hoard.
tire. 60-0-30. When required by the
Director, as the Uuly authorized agent
of the Uouril, the owner of any prop-
erty serviced by a sewer carrylup In-
dustrial or commercial waote shall
Install a suitable contiel manhole,
together with such neccnsory meters
and other appurtenances, to facilitate
observation, sampling and measure-
ment of the waste. Ouch manhole,
when required, shall be constructed In
accordance with, plans approved by
the Board's duly authorised profes-
sional engineering personnel. The
manhole shall be Installed by the
owner at the owner's expense, and
shall be maintained by the owner to
as to be free and accessible at all
times to the Hoard or Its agents.
When required, sanitary wests shall
be excluded lrom the control man-
hole.
n«i\ 50-0-27. All men.iuremonts,
testn nnd ntmlytes of tho characteris-
tic!] ol waters and waste, to which
reference 1& marie lu this ordinance,
Khnll be determined in Accordance
with the lalcBt edition of "Standard
Methods," an defined in Sec. 60-0-11,
and Bliri-lt bi> determined nt the con-
trol manhole provided or upon suit-
able samples taken at suld control
manhole, lu the event that no special
manhole has been required, the con-
trol manhole ohall be considered to
be the neareit downstream manhole
In the public sewer to the point at
which the newer Is connected. Sampl-
ing shall be carried out using the
best proctlcal technology.
Sec. 60-0-20. The duly authorized
employees of the Board, bearing prop-
er credentials and Identification, all all
ba permitted to enter all properties
for the purpose of Inspection, ob-
servation, measurement, sampling
and testing In accordance! with the
provisions of this ordinance. Duly au-
thorized employees shall have no au-
thority to Inquire Into any process,
Including metallurgical, chemical, oil,
refining, ccrainlc, paper or other In-
dustries, beyond that point having a
direct benring on the kind and
source of discharge to the sewers or
waterways or facilities for waste
trrnlmcnt.
Dec. 00-0-20. Wlille performing the
necessary work on private properties,
referred to In Hec. 50-0-20 above, duly
authorized employees of the Hoard
shall oboerve all safety, security and
other cotnpairy rules applicable to the
premises established by llie company.
Where requested by the property
owner or his agent, such persons shall
leave a portion of any sample taken
with such property owner or agent.
tlee. 60-0-30. No monitoring or sur-
veillance fees Mi at! be made on In-
duutrlat users operating- within the
limits of this ordinance. When the
limits of Incompatible wastes are
found to be exceeded, further mon-
itoring and ourvelllance shall be per-
formed aud the costs assessed to the
permittee. The additional fee shall be
determined on a graduated basis, us-
ing the volume of discharge to
determine a base fee which shall be
multiplied by a factor dependent on
the' concentration of incompatible
waste In the wastewater. Such ftea In
any consecutive six-months' period
shall not In total exceed the actual
monitoring and surveillance costs In-
curred by thn Hoard In auch six-
months' period.
Sec, S0-n-31. Damage* to pubtla
sewera, appurtenances, pumping sta-
tions, the wastewater plant or treat-
ment processes arising from harmful
Industrial waste shall be assessed to
the permittee. Such assessments shall
constitute a lien en tho property. The
Hoard reserves tho right to discon-
tinue service to any person, firm or
corporation for gross and repeated Vi-
olations of this ordinance, after writ-
ten notice has been given and a pub-
lic hearing has been called by the
Board at which tho peroon. firm or
corporation ha« been given an op-
portunity to show cause why his right
to service should not be discontinued.
Beo. B6-6-32. In order to control the
admission of Industrial waste to a
public aewer, any person desiring to
deposit or discharge an Industrial
waste Into the wastewater plant of
the Board, or any sewer connected
therewith, or who Is now so doing,
shall make application to the Board
within one hundred and twenty-five
(136) days from the data of passage
of thla ordinance for a permit
therefor, upon application forma to
be obtained from the Board or Its
duly authorised representatives. Only
bona-flde Industrial and commercial
users shall be eligible for a permit. No
municipality or combination of muni-
cipalities or collection agency shall be
eligible for an Industrial waste
permit. These forma shall Include an
Industrial waste questionnaire which
shall furnish pertinent data inclusive
of quantity of flow and an analysis of
the waste discharged to the sewerage
system. An up-to-date map, showing
all connections to the publlo sewers,
shall be furnished If required by the
Board.
Upon Issuance of the permit, the
permittee slmll henceforth ce;npl»
with all coticHtlona uf U;o penult or
be subject to the Itt-e established In
See. 68-0-30.
All permits t>h«Jl be updated and
renewed at five-year Intervals or audi
earlier time as may be necessitated by
changed conditions, rules, regulations
or laws.
See. 60-0-33. The Director, as the
duly authorized at;ont ol the Board,
shall be empowered to require all
UBers of the system tp comply with
all requirements of all applicable lo-
cal, county, ctate and federal laws, In-
cluding but not limited to United
States Public Law 02-600, as
amended, and the Michigan Water
Pollution Control Aot of li39, as
amended.
Sec. 60-6-34. Appeals regarding the
application of arty portion of this or-
dinance may be made at any time to
the Director and, further, M un-
resolved, In writing to the Board.
Sec. 56-8-36. Tills ordinance la
declared necessary lor the preserva-
tion of the public peace, health,
safety and welfare of the people of
the Olty of Detroit and Is hereby
given Immediate effect.
Sec. 60-6-30. All ordinances or parts
of ordinances In conflict here are
hereby repealed only to the extent
necessary to give this ordinance full
force and effect.
(JCO P. 674-77, March W, 1078)
Passed July 7, 1078.
Approved July 16, 1S76.
Published July 18, 1078.
Effective July 16, 1076.
17AME3 H. BRADLEY
Olty Clerk
-------
Putting Activated Carbon
In Perspective to
19Jtt G uidelines Davis L. Ford,
Engineering-Science, Inc.
Austin, Texas
INTRODUCTION
The applicability of the activated carbon process in treating
industrial wastewaters is contingent on many factors, including
the amenability of the dissolved constituents to sorption, the
presence of other substances which enhance or impede the
sorption process, the soundness of engineering, and proper
operation and maintenance of the system. As activated carbon
was one of the primary processes factored into the development
of the 1983 Best Available Technology (BAT) guidelines for
many industrial categories, some of which have been remanded
by the Courts, it is appropriate to discuss this form of treatment
in terms of "Best Available Technology." This discussion will
center around activated carbon experience in the treatment of
petroleum refining, petrochemical, and organic chemical waste-
waters as the remand of the 1983 guidelines for these categories
was primarily predicated on an insufficient technical basis. Asa
result of these court decisions, EPA is sending questionnaires
authorized under Section 308 of PL 92-500 to appropriate
industries requesting information on feedstocks, products, raw
waste loads, and treatment efficiencies realized from various pri-
mary, secondary, and tertiary processes. It will be the EPA
intent to use this information as the basis for repromulgating
BPT, BAT, and new source performance standards for the
Organic Chemicals and Petroleum Refining category.
Moreover, EPA is using carbon tests as one of the bases for de-
veloping toxic standards pursuant to its settlement agreement
with the National Resources Defense Council (NRDC).
The purpose of this paper is therefore to present a brief
chronological history of the promulgation, remand, and repro-
mulgation of these guidelines as related to activated carbon, de-
scribe some of the basic technological concepts of carbon
treatment, and document experience in treating these industrial
wastewaters using this process mode.
Description of Guideline Status
Effluent guidelines and standards of performance for new
sources were promulgated for the Organic Chemicals Manufac-
turing Point Source category in October, 1974. Additional reg-
ulations, including various new organic chemical products, were
promulgated by the EPA Administrator in January, 1976. Soon
after the promulgation, several corporations filed petitions for
review in the U.S. Court of Appeals for the Fourth Circuit. In
February, 1976, the Fourth Circuit Court of Appeals entered its
order providing the original regulations for the major organics
products segment and all subsequent amendments except that
portion related to the manufactur of butadiene be set aside and
remanded to EPA for reconsideration and repromulgation1.
Effluent guidelines and standards of performance for new
sources were promulgated for the Petroleum Refining Point
Source category in May and September of 1974, and amended in
May, 1975. For the 1983 BAT technology, EPA proposed an
end-of-pipe treatment system "based on the addition of acti-
vated carbon adsorption in fixed bed columns to the treatment
system proposed as 1977 BPT technology"2. EPA conceded that
"As for carbon adsorption, the Agency readily acknowledges
that it needs further development before it will show the high
degree of effectiveness in large-scale operations that it has
already shown in pilot-scale demonstrations." The American
Petroleum Institute filed a petition for review in the U.S. Court
of Appeals for the Tenth Circuit. In August, 1976, the 1983 BAT
portion of the Petroleum Refining guidelines were remanded to
EPA by the Court, stating that the "EPA acted arbitrarily and
capriciously in promulgating 1983 effluent limitations based on
petroleum refineries' use of carbon adsorption technology,
without demonstrating that such technology is available or eco-
nomically achievable." The remand of the BAT portion of the
guidelines was primarily attributed to the fact that the sole data
base was carbon isotherm test results using biologically treated
effluent.
These procedural facets have placed EPA in the position of
reevaluating the activated carbon process in terms of 1983
technology. As these guidelines will be repromulgated in late
1977, it is pertinent to consider this technology in perspective to
the 1983 requirements of "best available" and "economically
achievable."
Adsorption Concepts
The concept of utilizing activated carbon for adsorbing
organic materials dates back to the latter part of the nineteenth
century, primarily applied for the removal of taste and odor
compounds. Since that time, activated carbon filters have been
widely applied in both water treatment and wastewater reclama-
tion.
The rate at which substances are removed from the liquid
phase (adsorbate) to the solid phase (adsorbent) is of paramount
importance when evaluating the efficacy of activated carbon as a
wastewater treatment process. Unfortunately, the task of
quantifying the many forces acting at the solid-liquid interface is
a formidable one. Developing a mathematical expression which
describes the dynamic phenomenon occurring in a continuous-
flow/fixed-bed reactor has been difficult because of multi-
variable influences. The overall adsorption rate represents the
combined effects of diffusion through a laminar layer of fluid
surrounding the constituent, surface diffusion, and adsorption
on the internal pore surfaces. Most mathematical solutions for
48
-------
Activated Carbon 49
equations which describe concentration/ time profiles are limit-
ed to the special ease in which only one of these phenomena
controls the overall rate of adsorption1.
One expression for a continuous flow regime assumes the
diffusion of the constituent through the pores of the carbon
which are rate limiting, then combining these resistances in an
overall mass coefficient term. This is conveniently expressed in
terms of the adsorbate rate with respect to the weight of the
carbon in the columns:
V
~X~
(CSC)
(1)
dc
q dM
where: q = flow rate
Cs = concentration of the adsorbate
C = equilibrium adsorbate concentrate
K„r = overall mass transfer coefficient
d
M = weight of carbon in the column
X = packed density of the carbon in the column
The development of adsorbate removal kinetics on a batch
basis can be used to approximate carbon effectiveness and
predict organic residual levels. The adsorption isotherm is used
for this purpose and is defined as a functional expression for the
vairation of adsorption with concentration of adsorbate in bulk
solution at a constant temperature. The isotherm is expressed in
terms of removal of an impurity - such as BOD, COD, and col-
or - per unit weight of carbon as a function of the equilibrium
impurity remaining in solution. This expression relates the
amount of impurity in the adsorbed phase to that in solution:
- = KC1/"
M (2)
where: X = amount of impurity adsorbed
M = weight of carbon
C = equilibrium concentration of impurity in
solution
K,n = constants
The constants "n" and "k" can be used to define both the
nature of the carbon and the adsorbate. A high "K" and "n"
value, for example, indicate good adsorption throughout the
concentration range studied. A low "K" and "n" value would
infer low adsorption at dilute concentrations with high adsorp-
tion at the more concentrated levels.
It should be recognized that there are many factors which
influence carbon adsorption, and these models have only the
limited applicability of screening and comparing activated
carbons.
Factors Which Influence Adsorption
There are many factors which influence both the rate and
magnitude of adsorption - underscoring the difficulty in devel-
oping predictive models which would apply to all complex
wastewaters. A brief discussion of the more important factors is
presented herein.
Molecular Structure of the Adsorbate
The molecular structure, or nature of the adsorbate, is
particularly important in dictating the degree of adsorption that
can actually occur. As a rule, branched-chain compounds are
more sorbable than straight-chain compounds, the type and
location of the substituent (functional) group affects adsorbabil-
ity, and molecules which are low in polarity and solubility tend
to be preferentially adsorbed. Unless the physical blockage of
the carbon poifts Jctually occurs, large molecules are more
sorbable than snTO^TTiolecules of similar chemical nature. This is
attributable to more solute chemical bonds being formed,
making desorption more difficult. This is illustrated in Figure 1,
showing the effect of molecular size on sorbability for various
classes of organic chemicals based on isotherm tests4.
0.20
0.15
E
.1
0.10
J3
E
£
0.05
ESTERS
1 "¦ i
*-H*ionoi A
CaBrOK OCKt
/ /
rf /
/
/ .
/
J icttot*
ORGANIC
ALCOH
ACIDS
DLS
/A
f!
f
i
w
i
j
*jt icttotr
feme oe
0 20 40 60 80 100 120 140
MOLE
Figure 1: Adsorption of Specified Organics as a Function of
Molecular weight
Inorganic compounds demonstrate a wide range of adsorba-
bility. Disassociated salts - such as potassium chloride and
sodium sulfate - are essentially nonsorbable. Mercuric chloride
and ferric chloride are relatively sorbable, and iodine is one of
the most adsorbable substances known. Generally, however, a
significant reduction in inorganic constituents is not expected in
activated carbon systems.
Organic compound sorbability can be 'classified to some
extent. Primary alcohols and sugars, for example, are resistant
to adsorption, while ethers and certain organic acids are highly
sorbable. Recently published experimental data presented in
Table 1 are indicative of the sorbability of many organic
compounds?
Solubility
An increase in solubility acts to oppose the attraction of the
adsorbate to carbon. Thus, polar groups which have a high
affinity for water usually diminish adsorption from aqueous
solutions. Conversely, the greater adsorption of the higher
aliphatic acids and alcohols is attributed in part to their
relatively lower solubility in an aqueous solution. There are ex-
ceptions to this, as in the case of the highly soluble chloracetic
acid6.
Ionization
Ionization is generally adverse to adsorption by carbon as
strongly-ionized materials are poorly adsorbed. Hydrogen ions,
which are significantly adsorbed under some conditions, would
be an exception to this. Some negative ions, therefore, are more
sorbable when associated with hydrogen ions. For this reason,
mineral acids - such as sulfuric acid - are sorbable at higher
concentrations.
-------
50 Activated Carbon
Table I: Amenabilityfof Tjpical Organic Compounds to Activated Carbon Adsorption|4|
MmMi
MethaMl
P'OpiAOl
Buttnol
n Amyl ilcnM
n Huinol
ItOplOplNOl
Allyt alcohol
lsobut»flol
1 Bulinol
7 (Ihyl butinal
2 Ethyl hetinol
Mdihydes
P/opiOft»ld»hyde
Butyijldfhyde
Aciolem
Ciulonildthyde
Pliildehyde
Amines
0i H PiapylaniM
Buljlimiiie
Oi N RuMaimnt
Allylimifle
Munfliwiolimmi
D'Hhjnolimmt
Trielhanolimmi
MonaiiopioptnolimiM
0>isopiopjr>ol»min«
Pyridines 4 MorpMlm
Pyridine
7 Methyl $ (Ihyl
N Weihyl inorplteiilW
N t1h»i moipholiM
JUomities
Bfiwcne
Toluene
Ithyl bfnjtm
Phenol
Hyjioquinon*
Anihnc
Slyiene
Niliob«ni«n<
tston
Methyl Kftata
Ethyl jcrtiti
Propyt tut lit
tot ft KlMt
Pnm»ry iftfl K
Adwrbabtlitv*
UatoiHM
1 compound/
Percent
<*)
MM (C,)
Final (C()
I ta'bon
Reduction
32 0
oo
>000
964
0 007
36
461
oo
1000
901
0070
10 0
601
oo
1.000
111
0 038
189
74 1
7 7
1.000
466
o to;
53 4
112
1 7
1 000
717
0 ISS
71 8
102 2
0 58
1 000
4S
0 191
95 5
60 1
oo
1.000
174
0 0?5
176
58 1
oo
1.010
719
0 074
71 9
74 J
15
) 000
58)
0 081
4) 9
74 1
1 000
705
0 059
79 5
102 2
0 43
1.000
145
0 170
85 5
130 2
007
700
10
0 U*
915
30 0
I 000
908
0 011
97
44 1
CO
1.000
III
0 072
119
SB 1
22
1 ooo
773
0 057
77 7
J? 1
71
1.000
477
0106
571
S6 1
701
1 ooo
694
0 061
30 6
70 1
ISS
1 000
544
0 092
45 6
106 1
0 33
1.000
60
0 188
94 0
132 7
105
1 000
761
0 141
73 9
101 2
»
1.000
191
0 174
10 7
73 1
oo
1000
410
0 103
57 0
179 3
OO
1 000
130
0 174
17 0
57 I
oo
1.000
616
0 063
31 4
$0)
oo
1.000
893
0 071
10 7
103?
oo
1 000
706
0 062
79 4
61 1
oo
1 017
939
0015
7 7
I0S 1
95 4
996
122
0 057
27 5
149 1
oo
1 000
670
0 067
33 0
75 1
oo
I ooo
800
0 040
20 0
1332
17
1 000
543
0 091
45 7
791
»
1.000
577
0 095
47 3
121 2
li Ml.
1.000
107
0 179
19 3
10) 2
oo
1 000
S7S
0 085
47 S
1157
oo
1.000
467
0107
S3 3
71 1
0 07
416
71
0 010
ISO
97 1
0 047
317
66
0 050
79 2
1062
0 02
IIS
II
0019
84 J
94
(7
1.000
194
0161
101
110 1
(0
1.000
167
0167
133
9) 1
34
1000
251
0 150
74 1
104 2
003
110
II
0 071
III
173 1
Oil
1.073
44
0196
151
74 1
311
1.030
7(0
0054
2(2
III
17
1.000
495
0 100
SOS
1021
2
1.000
241
OKI
7S2
11(2
0M
1,000
154
Otll
Ml
1302
07
US
ill
0 I7S
HO
WHWItf
Cnwt>>»w
1 wui(C() riMiici)
Esters
Isopiopyl itelili
1071
21
1.000
311
0137
Kobutyl KtUlt
11(7
061
t .000
IK
0164
Vmyl icelile
161
71
1 000
)S7
0 179
Ethylene (lycol mortMlhyl «ttw Ktffti
> 1377
27 9
1.000
347
0 137
Ethyl adulate
1001
70
1.015
726
015)
Butyl aciyiile
1787
07
1 000
4]
0 193
Ethers
Isopiopyl elher
Butyl rihei
Dichloroif opropyl ethei
Glycols & Glycol E(h«ri
(thylrnt glycol
Dirihyl«ne (lycol
Iritlhylfoe (lycol
Teli j'thylen.* (lycol
Propylene glycol
Dipiopylene (lycol
He»y\»ri» tW'ot
Ethylene (lycol monomethyl ((few
Ethylene (lycol monMttiyl ftMf
HhyUne (lycol monobutyl «Hw
flhylene glycol monohtiyl «ttwf
Diethylene glycol monoethH •(*«
Dielhylene (lycol monobtrtjrf «Mmt
ElhOiylnglycOl
Hatogenated
(thylene dichlonde
Piopylcne dichlondi
Ketones
Orianic Actdt
Foimic and
Acelic acid
Propionic Kid
Bulync acid
Vilenc acid
Cipioic fcid
AcifTit icid
Benzoic icid
Oiidis
PropyitM 0»4t
Styi«ftt ond«
• Dou|t S | Cartas CA mMM.
107?
130?
in i
6? I
106 I
150 2
194 2
76 I
>34}
til?
76 I
90 I
III 2
146 2
134 1
162 2
I 71 2
99 0
1130
I 2
0 03
0 17
on
0)0
1,021
19/
I 003
1.000
I 000
1000
1 000
1000
I 000
3.000
1.074
1.027
I 000
9/5
I 010
i ooo
I ooo
1 000
1.000
410
(01
74 I
811
102 1
1162
721
122 1
SI I
1212
24
II
MS
03
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1,000
1.000
1.000
932
>31
477
419
114
135
386
III
70S
<41
121
5/0
in
30)
119
n
in
7(0
(74
10)
20)
30
3SS
19
7M
47
0162
0 039
0 200
0 0131
0 053
0105
0 116
0 024
0 033
0 122
0 071
0 063
on:
0 170
0 01/
0164
0139
0 161
0113
Acetone
511
00
1.000
712
0 043
Melhyietriyi ketone
72 1
2(1
I 000
S37
0094
Melhyl propyl kelOM
16 1
4)
1 000
30S
0 111
Mfthyl butyl kelone
1002
1 ll Ml
988
19)
0 ISI
Methyl iwbutyl ketoft*
1002
1 9
1 000
157
0161
Methyl tWimyl kltoM
1142
0 54
916
141
0161
Di'iotiiitjl ketone
147 7
oos
300
ml
00(0
Ctcioheiinone
912
25
1.000
332
0134
Acelophenont
170 1
OSS
) 000
71
0 194
Isopho'W
1317
1 2
1.000
34
0 193
0 047
0 041
oot*
1119
OISI
01*4
1179
Oil)
OOS2
01M
HI
120
M)
ISI
77 7
HI
MO
1000
1000
II
2(2
i? 3
SI I
IK
US
(I 4
US
310
»!
17 1
«3«
12 1
19 7
It t
12 9
It I
((I
MS
00 7
Ml
IS 2
100 0
(il
07 2
Ml
23 S
24 0
»t
SIS
212
170
US
>11
211
•SI
A change in ionization can drastically affect adsorption. A
low pH, for example, promotes the adsorption of organic acids
whereas a high pH would favor the adsorption of organic bases.
Phenol adsorbs strongly at neutral or low pH while the
adsorption of the phenolate salt at a high pH is poor. The
optimum pH is therefore solute-specific and must be determined
for each wastewater.
Temperature
As adsorption reactions are generally exothermic and high
temperatures usually slow or retard the adsoprtion process,
lower temperatures have been reported to favor adsorption3,6.
Very little information has been presented, however, which
documents significant shifts in adsorbability within the temper-
ature range of 65° F to 90° F (typical of most wastewaters).
Lower temperatures should increase adsorption, but the effect
in aqueous solutions is very small. The rate of adsorption is
strongly temperature dependent and therefore generally higher
temperature promotes better adsorption.
Adsorption of Mixed Solutes
M ost wastewaters contain a myriad of compounds which may
mutually enhance, interfere, or act independently in the adsorp-
tion process. Factors which affect overall adsorption of multiple
adsorbates include the relative molecular size and configura-
tion, the relative adsorptive affinities, and the relative concen-
trations of the solutes3. Predictive models obviously require
validation for complex wastewaters, as extrapolation from
investigations using synthesized wastes containing controlled
concentrations of selected adsorbates may not reflect all of the
interactions occurring in the waste. Mutual solubility effects
competition for adsorption sites, and the impossibility to
maintain a pH level optimum for all components contribute to
the difficulty in predicting the performance of activated carbon
treating mixed solutes, particularly when there is a time
variation in its composition.
Pretreatment Effects on Adsorption
It should first be stated that lack of pretreatment in removing
certain constituents can have an adverse effect on activated
carbon. Many of the negative aspects experienced in the
activated carbon treatment of industrial wastewaters has been
attributed to poor pretreatment. For example, fixed bed carbon
columns have a low tolerance for the free and emulsified oil and
grease constitutents prevalent in many wastewaters. Primary
and secondary oil removal is a prerequisite, reducing these
materials to less than 20 to 30 mg/1, concurrently providing
carbon-bed backwash capability. Sour waters have a deleterious
effect on fixed-bed operations, as the anerobic reduction of
sulfates creates odors and biological fouling in the bed.
Conversely, selected pretreatment can enhance carbon
adsorption performance. For example. Mercury II, present in
many waters as Mg(OH)2, which is a soluble uncharged species
is sorbable, although its degree of sorbability has been reported
-------
Activated Carbon 51
to be quite dependent on pH. The highest removal of Mercury II
occurs at a neutral pH, with decreasing sorbability at in-
creasing pH values. The addition of chelation agents such as
tannic acid prior to contact with activated carbon enhanced its
sorbability, as did increasing concentrations of the calcium ion.
This is illustrated in Figure 2, showing the effect of tannic acid
addition on the carbon removal of Mercury II, and Figure 3,
indicating the effect of calcium hardness on removing the
Mercury II - tannic complex7.
40 60 80
CARBON APPLIED (mg/l)
100
Figure 2: Influence of Tannic Acid on Removal of Mercury II
from Aqueous Solution by Powdered Activated Carbon
A somewhat related study indicated that many complexing
agents encountered in wastewaters exist as anions and are not
well adsorbed by activated carbon. Preliminary studies have
indicated that the coagulation of these wastewaters with iron
salts, aluminum salts, and possibly lime can alter the chemical
nature of these complexing agents, possibly making them more
amenable to adsorption on activated carbon8. The effect of iron
salt addition to solutions containing citrates, pyrophosphates,
or tannates are shown respectively in Figures 4, 5, and 6.
Addition of chlorine or ozone to wastewater streams subsequent
to carbon treatment has been reported to enhance adsorption
efficiency. Although chlorination of hydrocarbon-containing
wastewaters is disfavored in many regulatory circles, chlori-
nated hydrocarbons are more sorbable than their precursor.
Preozonation and carbon adsorption has been recently tested
with encouraging results''. The enhancement of adsorption BOD
removed efficiency using ozone pretr'eatment is indicated in
Figure 7IU. The results infer that some nonsorbable compounds
are converted to more sorbable intermediates through ozone
transformations. This possibility is substantiated in the litera-
ture, documenting ozone oxidation of aldehydes, ketones, and
alcohols to carboxylic acids, the products being more sorbable
than the reactants11,12. The potential advantages of such a
treatment mode include:
(1) the possibility of transforming nonsorbable compounds
to sorbable ones, enhancing overall carbon column
efficiency;
(2) reducing bacterial load to the carbon columns through
partial sterilization; and
(3) increasing the dissolved oxygen level in the carbon
column influent, reducing the possibility of sulfide
production and anaerobic bacterial activity.
There are possibly only a few of the potential pretreatment
applications which may enhance carbon adsorption efficiency.
This is obviously an area for further research and development
as many classes of organic compounds present in industrial
wastewaters are either nonsorbable or only partially removed on
activated carbon.
100
80
>
oc
360
£E
%
O
2
ui
IE
I 40
20
—i
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Hg II -
•
Ca,
*;20C
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i
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r- mnmf/'-
Ca
n;50>
nt/i
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r /
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r
k
pH'O
ALKAL1NH
TANNIC At
Y =Zm
"ID* In
>9/1
'g/l
f
20
40 60
CARBON APPLIED (mg/l)
80
100
Figure 3: I nfluence of Calcium and Tannic Acid on the Removal
of Mercury II from Aqueous Solution by Powdered Activated
Carbon
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TRATE
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SOLN.
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r1-
0 12 3 4 5 6
ACTIVATED CARBON DOSAGE (g/l)
Co* 70mg/l (0.36XI0"3M)
CITRATE/FE SOLN. MOLAR RATI0*l/l
AFTER 7 OAYS
Figure 4: Adsorption of Citrate by Activated Carbon
-------
52 Activated Carbon
o
UJ
m
a:
© I o
V) l u
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<
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o
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£ ACTIVATED CARBON DOSAGE (g/l)
Co ' 64 mg/l (0.36 X"3 M, os P£ 07 )
PYRO/FE SOLN. MOLAR RATIOM/I
AFTER 7 DAYS
Figure 5: Adsorption of Pyrophosphate by Activated Carbon
O
UJ 1.0
00
a:
o
(0 0.8
o
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0.6
O
<0A
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f.
/
'ANNAT
T/FF
SOLN.
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t -4
~—4
0 I 2 3 4 5 6 7
ACTIVATED CARBON DOSAGE (g/l)
Co = 609 mg/l (0.36X*3M)
TANNATE/FE SOLN. MOLAR RATIO = 1/1
AFTER 7 DAYS
Figure 6: Adsorption ot Tannate by Activated Carbon
Experience in Carbon Treatment
of Industrial Wastewaters
Although ample carbon treatment data from full-scale
facilities is becoming available from the municipal sector, much
of the performance data in industrial applications evolves from
pilot-plant studies. There are several full-scale carbon systems
treating industrial wastewaters, however, and this section
includes results from pilot studies and selected operational
systems. Specifically, results from pilot-plant studies conducted
by the author and literature reported performances will be cited
as the basis for discussion.
o
0
m
(-
z
in
1
2 5 10 20 30 40 50 60 70 80 90 95 93
% OF THE VALUES LESS THAN STATED VALUE
• NO PRECARBON OZONATION
A OZONE <6 2 mg/l
O OZONE -6.2 mg/l
D OZONE =3.2-6.2 mg/l
Figure 7: Frequency Analysis for Effluent BOD (CRSD
Precarbon Ozonation Study Westerly Pilot Plant)
There have been bench and pilot studies conducted in the
industrial sector evaluating activated carbon as both a total
(physical/chemical) process and as an effluent polishing (ter-
tiary) unit. The first comprehensive testing of industrial waste-
waters using batch activated carbon isotherms demonstrated
rather optimistic results for several industrial categories12. These
results were based on the isotherm testing of 222 samples of
industrial effluents. This analysis, however, glosses over many
of the limitations which are inherent in treating most
wastewaters, namely, the inability of carbon systems to remove
significant fractions of organic compounds in selected waste
streams within an industrial category, and failure of the batch
isotherm test to reflect the process and solute variables pre-
viously described. It also should be noted that adsorptive
capacities based on isotherm tests for industrial wastes have
been reported to yield falsely high assessments of continuous
carbon system performance". Results of comprehensive carbon
pilot testing of refinery wastewaters by the author are cited in
Table 11, the average organic removal being significantly less
optimistic than that indicated in the isotherm tests. A compre-
hensive pilot-plant study treating petroleum refinery effluents
by activated carbon also was conducted recently by the Environ-
mental Protection Agency14. Both API separator effluent and
biologically treated effluent were charged to the columns in
order to obtain a comparative evaluation. It is apparent that,
when operated in parallel, the biological system was more
effective in removing BOD and COD - particularly the former.
This is consistent with the results observed in pilot studies
conducted by the author. It is also noted that carbon adsorption
following biological treatment was particularly effective in
reducing both the BOD and COD to low levels. The residual
COD is in the same range as that cited in Table II when the
carbon application mode and influent COD levels were similar.
It is noted that there is no removal of cyanides or ammonia
although there was a reduction of the cited organic constituents,
particularly phenols.
-------
Activated Carbon 53
Table II: Carbon Pilot-Plant Results for Petrochemical and Refining Wastewaters
Type of Wastewater
Design
Q
CRGD)
Process
Application
Influent
COD (nig/1)
Eff1 uent
C0D(mg/l)
Percent
Removal
Refinery
28
Physical/Chemical
600
103
83
Refinery
1.9
Physical/Chemical
800
201
75
Refinery
22
Physical/Chemical
670
143
79
Petrochemical
3
Tertiary
150
49
67
Refinery
26
Tertiary
100
41
59
Refinery
28
Tertiary
300
50
83
Refinery
8
Tertiary
100
40
60
Petrochemical
29
Tertiary
150
48
68
These pilot studies underscore the need to temper the
optimism derived from batch isotherm results with a more
realistic evaluation of those factors which limit the practical
application of carbon. Even pilot plant testing may fail to reveal
all the process inadequacies which may apper appear in the full-
scale application of carbon. This was exactly the case for two
full-scale carbon plants in the refining industry which were
designed from pilot-plant data. These systems, located in
Wilmington, California, and Marcus Hook, Pennsylvania,
failed to perform at the level predicted by pilot-scale testing10.
The failure to properly account for the effects of virgin carbon
testing as compared to regenerated carbon utilization in the
field, the difficulty in securing representative wastewaters
during the last phase, and the failure to recognize and account
for the process and solute variables when designing and
operating the system have all accounted to some degree for the
disappointing record to date of successfully treating industrial
wastewaters using activated carbon.
Activated carbon treatment of industrial wastes, while
promising, must be carefully evaluated before process decisions
are made and capital funds are committed. As noted in this
discussion, breakthrough geometry and adsorption kinetics of
multi-component wastewaters are difficult to define, many
organic compounds are not amenable to carbon adsorption, and
the effects of regeneration on carbon capacities are variable and
unpredictable. For these and other reasons, comprehensive
testing, technical reviews, and appropriate scale-up factors are a
necessary prerequisite to process commitment.
Unfortunately, most of the literature regarding carbon
treatment of industrial wastewaters centers around bench and
pilot-plant results. There are, however, sufficient data from pilot
studies and the two full-scale systems in the petroleum refinery
industry to draw general conclusions, at least within this
industrial category.
The distribution of influent and effluent COD from a full-
scale activated carbon facility treating combined storm runoff
and process wastewater at the ARCO Refinery in Wilmington,
California, is shown in Figure 810. The effluent quality data from
a carbon adsorption system treating process water from the
British Petroleum Refinery in Marcus Hook, Pennsylvania, is
tabulated in Table III10. As observed in this table, there were
four distinct phases of operation since the carbon system came
on line. The first period occurred when virgin carbon was in the
adsorbers and the foul water condensate stream from the
Fluidized Catalytic Cracking Unit(FCCU) was not yet included
in the raw wastewater stream. The second period included the
FCCU stream, but virgin carbon was still present in the
adsorbers as the wave front had not yet reached the top of the
carbon bed. The third period encompassed a time following a
complete turnover of the carbon bed and still included the
FCCU stream. The fourth period excluded this stream and
incorporated a modification to the column septum design, still
following a complete carbon turnover. A deterioration of
effluent quality through these four phases of operation noted in
Table 111 underscores the need for documenting performance
under all operating conditions before assessing carbon applica-
bility. A distribution of long-term average COD concentrations
in effluents from carbon adsorbers treating refinery wastewaters
is presented in Figure 915. These levels are relatively consistent
with those residuals reported in previous case histories and rep-
resent a spectrum of COD residuals in carbon-treated effluents,
these residuals being attributed to nonsorbable compounds as
previously discussed.
SUMMARY
A review of the activated carbon treatment of industrial
wastewaters has been presented. It is recognized that new truths
pertaining to this subject become known on a continuing basis.
However, in evaluating process concepts, developing design
bases, predicting effluent quality, and finalizing management
decisions in terms of constructing control systems with attend-
ant capital commitments, one must carefully base these judg-
ments on the known process capabilities and limitations of
activated carbon, particularly when pursuing BAT effluent
requirements.
Some of the significant factors presented in this paper include
the following:
(1) Adsorption theory is rigorous for single solutes, but
becomes less definitive when applied to wastewaters
containing multiple components with varying molecular
weights and chemical characteristics.
(2) Batch isotherm studies are not necessarily indicative of
continuous flow carbon treatment systems.
(3) Many classes of organic compounds are not amenable to
carbon adsorption - particularly oxygenated organics -
and show up as residual BOD, COD or TOC in carbon
column effluents. This limits the overall process efficiency
-------
54 Activated Carbon
of activated carbon when treating many industrial
wastewaters.
(4) As effluent quality requirements become more stringent
under the 1983 BAT guidelines, activated carbon will be
considered as a candidate process, primarily through the
selective treatment of individual process streams or as an
effluent polishing process. It is imperative, however, that
its limitations be understood when considering its
application in terms of BAT quality requirements.
400|
450r
hi
o
g
£
o
<
o
8
10 20 30 40 50 60 70 80 90 99
* OF THE VALUES LESS THAN STATED VALUE
~ INFLUENT ¦ O EFFLUENT- •
Figure 8: Performance of Arco Carbon Plant (COD Removal)
o
o
o
z
14
D
U.
Id
U
z
z
cc
(9
z
o
PERCENT OF PILOT-PLANT OR FULL-SCALE SYSTEMS
TREATING REFINERY OR RELATED WASTEWATERS
WITH LONG TERM MEAN COO LESS THAN
STATED VALUE
Figure 9: Effluent COD Attainable from Activated Carbon
Systems
REFERENCES
l.Goleman, R. K., Memorandum of Law, unpublished,
(February 8, 1977).
2. Seth, Breitenetein, & Doyle, Circuit Judges, Opinion, U.S.
Court of Appeals, 10th Circuit, American Petroleum
Institute of U.S. Environmental Protection Agency,
(August 11, 1976).
3. Weber, Walter J., Physuochemical Processes for Water
Quality Control, John Wiley and Sons, Inc., New York
(1972).
PERIOD 1
Table III: Process Performance (BP Marcus Hook)
PERIOD 11 PERIOO III
PtRlOB l»
Filter
Carbon
Cartoon
Filter
Carbon
Carbon
Filter
Carbon
Carbon
Filter
Carbon
800 Av«.
Influent
Influent
Effluent
Influent
Influent
Effluent
Influent
Inf1uent
Effluent
Influent
Influent
76
46
40
75
78
72
.
.
88
55
Max.
-
-
-
-
-
-
-
-
•
C0D Avg.
386
216
63
388
296
133
415
322
242
408
301
Max.
478
248
77
522
361
184
660
400
300
500
390
TSS Avg.
70
16
11
88
34
21
67
20
16
64
16
Max.
95
29
14
115
52
67
126
34
43
74
29
OAG .
Avg.
21
10
<1
74
25
8
67
10
2
78
13
Max.
34
19
<1
143
66
28
114
16
3
125
22
Phenols
Avg.
21
20
0.023
14
12
4.5
32.5
32
12.9
2
1.9
Max.
21
20
0.028
19
22
6.4
34.5
33.5
20
3.8
3.7
Sulfides
Avg.
-
0.19
13.8
-
-
-
-
7.5
11.2
-
0.6
Max.
-
0.35
18
-
-
-
-
16.8
37
-
0.9
NH1-N
Avg.
.
15
19
-
-
-
-
87
93
12.3
Max.
-
16
20
-
•
•
-
103
110
13.5
Cirton
E'flutnt
65
253
330
55
99
16
0.7
0.8
13
25
13
IS
-------
Activated Carbon 55
4. Lawson, C. I ., and Hovious, J. C\, "Cautions and Limita-
tions of Activated Carbon Adsorption to Organic Chemical
Wastewaters," Proceedings, Open Forum on Management
of Petroleum Refining Wastewaters," sponsored by the
Environmental Protection Agency, the American Petro-
leum Institute, the National Petroleum Refiners Associa-
tion, and the University of Tulsa, (January, 1976).
5. Giusti, D. M., Conway, R. A., and Lawson, C. T.,
"Activated Carbon Adsorption of Petrochemicals," Jour-
nal, Water Pollution Control Federation, (May, 1974).
6. Hassler, John W., Purification with Activated Carbon,
Chemical Publishing Company, Inc., New York, (1974).
7. Thiem, L., Badorek, D., and O'Conner, J. F., "Removal of
Mercury from Drinking Water Using Activated Carbon,"
Journal, AWWA, (August, 1976).
8 Weber, Walter J., and Kavanagh, JosephT.,"Effect of Iron
Coagulation on Activated Carbon Adsorption of Complex-
ing Plants," presented to the American Chemical Society,
New Orleans, (March 22, 1977),
9 Guirguis, W., Cooper, T., Harris, J., and Unger, A.,
"Improved Performance of Activated Carbon by Pre-
Ozonation," 49th Annual Conference, WPCF, Minneapo-
lis, (October, 1976).
10. Ford, D. L., "Current State of the Art of Activated Carbon
Treatment," Proceedings, Open Forum on Management of
Petroleum Refining Wastewaters," sponsored by the
Environmental Protection Agnecy, American Petroleum
Institute, the National Petroleum Refiners Association,
and the University of Tulsa, (January, 1976).
11. Evans, F. L., Ozone in Water and Wastewater Treatment,
. Ann Arbor Science, Inc. (1972).
12. Snolyink, V. L., Weber, W. L., and Mark, H. B.,"Sorption
of Phenol and Nitrophenol by Activated Carbon," Envir-
onmental Science & Technology (October, 1969).
13. Union Carbide Corporation, Comments Relative to Unit-
ed States Environmental Protection Agency Proposed
Rulemaking, 40 CFR Part 414, Organic Chemicals Manu-
facturing Point Source Category as published in the
Federal Register, (Sept. 10, 1975).
14. Short, T. E., and Myers, L. A., "Pilot Plant Activated
Carbon Treatment of Petroleum Refinery Wastewaters,"
Robert S. Kerr Environmental Research Laboratory, Ada,
Oklahoma, (1975).
15. Engineering-Science, Inc., Report to the National Commis-
sion on Water Quality, Petroleum Refinery Industry -
Technology and Cost of Wastewater Control,(June, 1975).
-------
Reductive Degradation for the
Treatment of Chlorinated
Pesticide Containing
Wastewaters
K. H. Sweeny
Envirogenics Systems Company
El Monte, California
INTRODUCTION
An important problem facing those concerned with maintain-
ing clean waters is the discharge of chlorinated hydrocarbon
wastes from the manufacture or processing of pesticides and
industrial chemicals. An area of particular concern within this
problem is the treatment of the chlorinated hydrocarbons
soluble in water, since the soluble material clearly can not be
removed by filtration, and is generally resistant to conventional
biological treatment.
An earlier study directed towards the development of means
for the degradation of DDT surveyed a number of chemical
techniques for the destruction of the pesticide, and the impor-
tant finding was made that DDT, as well as a number of other
halogenated toxicants, could Be degraded by a chemical
reduction technique. The results of some screening tests with
DDT, in which DDT was treated with generally an equal
amount of the cited material are shown in Table I. Since the pro-
duction of such products as DDE was to be avoided, and a room
temperature reaction was desired, chemical reduction was the
preferred method of degradation. Subsequent work has led to
the discovery of a catalyst for the process which appears to lead
Table 1: Some Possible Chemical Techniques for Degradation
of DDT
LEWIS ACIDS:
AlClj, AlBrj
extensive degradation at 25, 50,
100 *C. DDE a substantial product.
F eC 1 3
• less effective than A IC I
REDUCTION:
Zn + dil acetic acid
- complete degradation of DDT with-
out DDE as a product. Reaction
proceeds at 25 *C.
FREE RADICAL:
Benzoyl peroxide
- complete conversion to DDE at
100 *C; little reaction at lower
temperatures.
Other peroxide catalysts
- none effective at ambient
temperature.
OXIDATION:
Hot chromic acid
(117 - UO'C)
- slow reaction; 40% DDT reacted
in 8 hr.
KMn04
- little reaction at 25 'C.
ALKALINE HYDROLYSIS:
KOH - ethanol
' essentially complete conversion
to DDE at 78 *C,
KOH - n-butanol
- conversion to DDE and other pro-
ducts at 117 *C.
KOH - ethylene glycol
- complete consumption of DDT at
168 - 175 *C, mainly giving
to a more complete and more rapid reaction at ambient
temperatures.
Toxicants Reduced
Additional studies have shown that the catalyzed reductive
degradation reaction has broad applicability for the treatment
of chlorinated toxicants and industrial pollutants. Some of the
toxicants found to be degraded by the catalyzed dissolving metal
reduction are shown in Table II. Of many substances examined,
only DDE (a common constituent of technical DDT) was found
refractory to the catalyzed metal system.
Table II: Chlorinated Hydrocarbons Reduced by Catalyzed
Metal System
C YCLODIENES
aldrin
chlordane
dieldrin
endrin
heptachlor
heptachlor epoxide
isodrin
[chlorinated camphene
DPT-Type
DDT
DDD
Kelthane
Methoxychlor
Perthane
toxaphene
[light ends
CHLORINATED GYCLOHEXANE
lindane
CHLORINATED PHENOXYACETIC ACm
carbon tetrachloride
chloroform
methylene chloride
chlorobromomethane
2, 4-D ester
2, 4, 5-T ester
-HumivAT°vEYCLOPENTAD1FM°'
Hexachlorocyclopentadiene
Kepone
Ipolychlorinated biphenyls
Aroclor 1016
Aroclor 1221
Aroclor 1242
Aroclor 1254
Reductants
The reductants generally employed have been powders of
iron, zinc or aluminum. All of these metals are effective
reductants, though iron is generally preferred on the basis of
effectiveness at low cost and freedom of deleterious reductant
products; zinc ion, for example, in the waters would offer
orobletns unless removed.
Although the reduction appears to be mainly one of dechlori-
nation, other products may be obtained, depending on the
reductant system employed. The reduction of DDT, for exam-
ple, can be modified depending on the reductant employed to
give the following major products:
56
-------
Reductive Degradation 57
Catalyzed Zn, H
[OJci + [Ol ci ci fOJ
' Catalyzed Al, H I i
H-C — C-Cl 1 -**¦ H—cT—C C C —H
(£>) " "
CI
Catalyzed Fe, H+ tttti
CI
if)
H —C — COOH
TTTB +
CI
DDA
it is thus seen that the reaction may apparently proceed by
dechlorination, a reductive coupling to a large, insoluble
molecule (TTTB), or a process involving hydrolysis (DDA).
These products have been confirmed by gas chromatography
(DDET), mixed melting points with authentic material (DDEt,
DDA, TTTB), and infra-red (DDEt, DDA, TTTB) and nuclear
magnetic resonance (TTTB) spectroscopy.
Reductive Column
While the degradation of some toxicants can be achieved by
stirring a solution of the toxicant with catalyzed reductant, it
was observed that the more stable materials required a different
contacting technique for effective reaction. The passage of
toxicant-laden solution through a bed containing the catalyzed
reductant metal powder mixed with a diluent such as sand is the
preferred method, although fluidized beds of reductant can be
used. Typical beds will contain 5 to40% catalyzed metal powder
£-150/J.m dia) mixed with diluent of an approximately equal size
to give suitable residence time in the column and reasonable
flow properties through the bed.
The depth of the bed also appears important in the effective-
ness of a reductive column. For many materials, a bed depth of
at least 150-160 cm appears necessary-for complete degradation.
With sufficient column depth, degradation to detection limits
(electron capture detection, gas-liquid chromatography) has
been achieved. This effect may be illustrated with data from the
degradation of an endrin/heptachlor containing waste. Bed
depths of 93, 122, 156 and 187 cm were used, with pressures
ranging from a 10 cm static head to 14 psi applied pressure.
While heptachlor and endrin appeared absent in all samples,
chlordene, a precursor of heptachlor was present in small
quantities with a 90 or 120 cm bed, was reduced to trace
quantities at 150 cm and was not present at detection limits
(~0.017/ig/fi) with the 180 cm bed depth. Similar results were
shown with hexachloronorbornadiene and heptachloronorbor-
nene, precursors of endrin.
Bench-Scale Test Unit
Scale up of laboratory tests to a bench-scale test unit
permitted the collection of data at a higher flow rate and more
nearly simulating treatment plant conditions. The reductive
column employed in these tests consisted of 9 ft of 6-in. dia. glass
pipe. The column was supported by either a stainless steel screen
(20 mesh) and a 2-in. mat of glass wool, or graded rock and
gravel (coarse, medium, fine) used for sand filter support. Flow
through the bed was maintained by a small pump (max capacity
8 gpm at 0 pressure) supplied from a stirred 200 gal tank. The
flow was maintained by either (a) a level control to give constant
static head, or (b) pressure control up to 15 psi. An example of
the results obtained is shown in Table 111.
Table III: Degradation of Endrin-Heptachlor Waste in Bench-
Scale Reductive Degradation Unit
Component
Chlordene
Endrin
Heptachlor
Heptachlor epoxide
Flow Rate
Analysis, fig/l
Waste to be Treated Effluent
50
300
30
30
1.7 i/m
Z, Z gpm/sq ft
< . 017
<. 031
< . 017
. 02
It is thus seen that the reductive degradation system has given
essentially complete degradation of the endrin, heptachlor and
their precursors and by-products, with levels in theeffluent at or
below detection limits. Samples from this series were analyzed
by combined gas chromatography-mass spectrometry
(GC/MS) at the Athens EPA laboratory where none of the
starting materials was found in the effluent at detection levels. In
other GC/MS studies at the Denver EPA labs, dechlorinated
species including products such as methyl napthalene were
found in the effluent stream. The effluent also contains about
4-5 mg/Kferrous iron from the dissolution of the reductant.
Reduction Plant
A plant has been constructed and installed for the treatment
of endrin-heptachlor containing wastes. The schematic for the
process is shown in Figure 1, and consists of three basic steps:
filtration, pH adjustment, and treatment. Filtration to remove
particulate matter is necessary since foreign matter could plug
the column, leading to excessive pressure drop, channelling, etc.
Since there is a large density difference between the iron
reductant and the sand diluent, back washing of the column to
remove suspended matter would lead to segregation of the
column packing. Strong oxidants such as free chlorine, or other
reductant-consuming components if present in the feed, would
also require removal by pretreatment. The second step involves
pH adjustment if the solution to be treated is markedly different
from neutral. High acidity leads to excessive consumption of
reagent, while alkaline solutions (e.g.,>pH 8) can lead to
precipitation of hydrous iron oxide floe in the column as well as
poorer reductive action.
The constructed plant has a capacity of 100 gpm, with the
reducing action taking place in four 3 ft dia x 8 ft tall tanks. A
view of the plant without the filter is shown in Figure 2.
This plant has been installed and initial operations have
shown excellent degradation. In several early tests, levels of
endrin and heptachlor in the effluent have been below detection
limits of 0.01 /xg/C-
Estimated Treatment Cost
The estimated treatment cost for the reductive degradation
process is low, since the labor and chemical requirements are
both minimal. An estimate has been made for a 100 gpm plant
operating on a continuous basis. These costs, summarized in
Table IV, indicate an estimated operating cost (labor, labora-
tory testing, power, chemicals, maintenance and supplies) of
$0.46/1000 gal, and an amortized capital investment of
$0.29/1000 gal, giving a total treatment cost of $0.75/1000 gal.
Experience to date suggests that the estimate is reasonable. It is
estimated that the reductant charge in a unit of this type will last
-------
58 Reductive Degradation
Figure I: Reductive Treatment System
Table IV: Estimated Cost for Treatment by Reductive Degrada-
" ' ' — ^nnrnjinrl\
— Operating Cost
Total Cost. $/day
Operators
Laboratory Technicians
Chemicals and Power
Maintenance and Supplies
14. 28
17.85
25. 66
8. 91
Total
$/1000 gal Effluent
66.71
0. 46
Amortized Capital Investment
(10 year at 9%)
Total Cost
Operating Cost
Amortized Capital Investment
42. 22/day
$ 0.29/1000 g*1 effluen1
«/1000 qal effluent
$ 0,46
0. 29
TOTAL
$ 0.75
Table V: Reductive Degradation of Polychlorinated Biphenyls
1221
1242
125*
Chlorine, % (approx.)
21
4a*
54
Influent Solution, IS.
343
250
43
Effluent, H-g/f
dichloro, <2, 4-,
4'-,
4, 41 -
1.0
0.0
-------
Reductive Degradation 59
Figure 2: 100 gpm Reductive Treatment Plant.
Front View, Showing Control Panel, pH Neutralization Circuit,
and Reaction Vessels.
-------
Biological Treatment of
Concentrated Nitrate Waste
F. E. Clark
J. M. Napier
Union Carbide Corporation-
Nuclear Division
and
R. B. Bustamante
Tennessee Technological University
INTRODUCTION
Large amounts of nitrate-rich waste are produced in the
purification of uranium at the Oak Ridge Y-I2 Plant of the
Energy Research and Development Administration, operated
by Union Carbide Corporation, Nuclear Division. These wastes
result from the liquid-liquid solvent extraction procedures used
in the uranium purification process, where nitric acid is a
principal reagent. In the past, these waste solutions have been
pumped into a series of four ponds, each of which is approxi-
mately one acre in surface area and twenty feet deep. No
overflow over or around the ponds has occurred, and evapora-
tion and percolation into the soil have kept the ponds below the
overflow level.
As a result of changes in state and federal water pollution
control laws, efforts were initiated to consider other methods for
the disposal of nitrate wastes in an environmentally acceptable
manner. In 1972, a study was made of several methods of
disposal and/or management of the waste solution, and an
option involving (a) recovery and recycle of usable chemicals,
and (b) biodenitrification of the remaining nitrate was selected
for further study and development. It is with the biodenitrifica-
tion of the nonrecycable nitrate wastes that this paper is
concerned.
After extensive laboratory and pilot-plant development
work, a full-sized biodenitrification plant has been constructed
and is now in full operation. These treatment facilities consist of
two 25,000-gal (95 m3), continuous flow, stirred bed anaerobic
denitrification reactors. The initial operation and performance
of these treatment facilities are discussed in the body of this pa-
per.
Literature Review
Biodenitrification has been described as the enzymatic
reduction of nitrates and nitrites by bacteria to nitrogen gas.1 A
number of heterotrophic microorganisms are capable of effect-
ing denitrification, among them are included organisms of the
genera Pseudomonas, Thiobacillus, Micrococcus, and Achro-
mobacter. The process involves the reduction of nitrate to
nitrous oxide and nitrogen gas. As the system increases its
oxygen limitation, a higher percentage of nitrogen gas is pro-
duced.1
For denitrification to take place at a rate that may be usable in
water pollution control processes, various chemical parameters
must fall within a range suited to the denitrifying bacteria.
Variations in pH are of critical importance in the denitrifying
process. Valera and Alexander2 have shown that denitrifiersare
sensitive to low pH, as the percentage of such organisms in the
soil was greatly reduced below pH 6.0. Wijler and DelwichJ
found that below pH 7, nitrous oxide (N,0) was the major
denitrification product in soils. As shown by several
researchers,4,5 nitrate reduction is optimum in the pH range of
6.5 to 7.5.
Temperature is a critical factor in denitrification. Mechalas,
Allen, and Matgskiel/4 found that the denitrification rate
doubled for a 10°C increase in temperature. Bremmer and
Shaw6 confirmed the above, but noted that rate increase was less
pronounced at higher temperatures. They also found maximum
denitrification to occur at 60°C.
Several organic compounds have been successfully used as
carbon sources in denitrification. Methanol is commonly used
because of availability and economics. Christianson, Rcx>
Webster, and Virgil1 utilized sugar and methyl alcohol as carbon
sources while working with concentrations of 250 to 100 mg/l
sodium nitrate. McCarty, et al* showed that methanol, ethanol,
acetone, sugar, and neutralized acetic acid could be used in the
denitrification process. His work indicated that an organic-to-
nitrate mole ratio of 1.3 to 1.4 is needed. McCarty also showed
that neutralized acetic acid solutions were decomposed at a
more rapid rate than methanol solutions. Methanol, however,
was the recommended substrate because of operating econom-
ics.
A literature survey is presented by Francis and Callahan* on
the effects of nitrogen compounds in water. These include pub.
lie health factors such as the development of methemoglobin©.
mia in infants and livestock, thyroid disturbances, and repro-
ductive difficulties. Environmental effects have been the
eutrophication of lakes and other bodies of water.
Clark, Francke, and Strohecker10 reported on the biodenitri-
fication development work carried out at the Y-12 Plant.
Columnar studies were investigated but abandoned because of
constant plugging problems. A continuous-flow stirred bed
reactor approach was adopted and tested through bench-scalc
and pilot-plant investigations. It was found that nitrate solu-
tions as high as 15% by weight can be successfully introduced
into biological denitrification systems. Nitrate removal efficien-
cies of 99% plus were consistently noted. Calcium acetate was
used as the main carbon source with very satisfactory results.
The pH of the system was maintained at 6.5 to 7.5, and the
carbon dioxide content in the offgas was found to be a very
useful indicator of the health of the biological reaction.
Process and Methods
Denitrification Process Description
The object of the plant constructed at the Y-12 Plant is the
biological reduction of the nitrate ions in waste solutions to
60
-------
Biological Treatment 61
NO3", CARBON
<3r
SOLUTION.
SOLIDS
POCKET
Figure 1: Biodenitrification Stirred Bed Reactor
nitrogen gas (N2). The gas thus produced is discharged into the
atmosphere where it is deemed to be perfectly harmless.
The denitrification facility now being operated at the Y-12
Plant is centered around two 25,000-gal (95 m3) modified water
softening tanks with associated stirring equipment, plumbing,
controls, and test equipment. Each of these units is operated at
an average liquid capacity of 78,000 . These tanks are properly
sealed to exclude air and are capable of decomposing 345,000 kg
per year of nitrate wastes. These units are intended to be
operated in parallel, and presently one is being operated while
the second is being kept on standby. A diagram of one of the
stirred bed units is given in Figure 1.
Two large feed tanks are provided; one for the organic feed
and one for the mother liquor. This first tank is made of stainless
steel and has a capacity of 10,000 gallons. The organic feed tank
has a capacity of 10,000 gallons and is made of black iron. A
third, and much smaller, stainless steel tank, with a capacity of
45 gallons, is used to introduce inorganic nutrients into the feed.
The plant operator has the ability to pump metered feed into
the denitrification units. Control equipment at his disposal
permits him to continuously monitor total organic carbon
(TOC), pH, temperature, nitrate, total gas output, and percent
CO 2 in the off gas.
Waste Solution
The Y-12 Plant uses large amounts of nitric acid in the solvent
extraction purification of uranium. Recycle and reutilization of
waste accounts for the recovery of approximately 61% of the
nitrate waste. Recycle involves basically two operations: (1)
distillation and recovery of free nitric acid, and (2) evaporation
and crystallization of aluminum nitrate [A1(N03)3.9H20].
The nitrate waste stream that remains after the recycle
operations is referred to as "mother liquor". Such a liquor
contains calcium, magnesium, and aluminum in substantial
amounts, in addition to iron, nickel, molybdenum, tungsten,
titanium, and zirconium impurities. A typical mother liquor
chemical analysis is given in Table 1.
Table I: Typical Analysis of "Mother Liquor"
Concentration
(wt »
Aluminum
4.4
Magnesium
0.4
Calcium
0.8
Sodium
0.2
Potassium
O
O
O
O
iJ
Lithium
0.01
ft
O
O
Molybdenum
O
©
ft
O
O
Zirconium
1—{
O
O
ft
O
O
Silicon
r—1
O
O
to 0.1
Nickel
0.01
to 0.1
Fluorides
0.5
Free Nitric Acid
3.5
Total Nitrate
33.0
Hater
59.1
-------
62 Biological Treatment
ll is also to be noted that the nature of the mother liquor is
such that at least trace quantities of all common elements can be
detected in it. An additional feature of the liquor is that its
chemical composition may be expected to change from day to
day in ways which are beyond the control of the denitrification
plant operator.
The reactor feed for the denitrification is made up of a
combination mother liquor and organic feed. As noted above,
the organic material deemed most satisfactory is calcium
acetate, and such is being used at a concentration of approxi-
mately 17% by weight. A typical reactor feed analysis is given in
Table II.
Table II: Typical Reactor Feed
Concentration
(wt %)
Water
Total Nitrate
Total Calcium Acetate
Miscellaneous
70.9
15.4
12.3
1.4
In addition to the above feeds, an inorganic nutrient solution
containing phosphates is added to the reactor. In effect, there
are three solutions (nitrate wastes, organic feed, and inorganic
nutrients) which are pumped on a continuous basis into the
reactor tanks.
6.0 L
S.OU
4.0 L
Biological Seed
Seed for the initial operation o! the reactor was grown in sev-
eral 55-gallon drums. These drums were continuously agitated
by bubbling nitrogen gas into them. Such a procedure helped in
the elimination of any oxygen that may have been present in the
fluid. The tanks were seeded initially with cultures derived from
the bench-scale denitrification units. The tanks were fed daily
with calcium acetate and calcium nitrate, and nitrate and pH
were monitored each day.
The initial seed for the full-si/e reactor was provided by ten of
the above-described drums. In addition, as many as 150 pints of
seed were freeze-dried and stored lor future use.
Operational Results
Only one of the two biodenitrification reactors has been used
to date. Startup procedures included the following steps:
1. Fill tank with water
2. Add sodium carbonate or bicarbonate
3. Adjust pH to the range 7.0 to 8.3
4. Add calcium nitrate to a level of approximately 500 mg/1 in
the tank
5. Add calcium acetate to approximately 133 mg/1 in the tank
6. Add phosphate to a level of approximately 20 mg/1 in the
tank
7. Add inorganic nutrients
8. Add bacterial seed
9. Operate the reactor without additional feed until nitrate
decreases to 200 mg; 1 or less
10. Start feed flow
It is to be noted that the reactor is not operated as a true
continuous-flow system. Although feed is continuously intro-
duced, the effluent is removed in batches. I.arge amounts of
solids, particularly calcium carbonate and aluminum hydrox-
ide, are produced, and the resulting sludge is removed daily in
600-gallon batches as required. Theoretically, it was expected
a
E
^ ,w Time, Day
Figure 2: Nitrate Feed Rates and Reactor Temperature
-------
Biological Treatment 63
6.0
5.0
4.0
3.0
2.0
1 .0
4 Temperature
• NO^ Feed Rate
35 40 45 50 55 60 65 70
Time, Days
Figure 3: Nitrate Feed Rates and Reactor Temperature
that 1590 pounds of solids and 1886gallons ofwater would have
to be removed each day. The water and solids are being taken
from the reactor simultaneously with a Dempster truck and
buried.
The plant was started on September 17, 1976 following the
above-noted procedures. After two days of operation on a batch
basis, continuous feeding was begun September 20. Figure 2
shows the nitrate feed rate into the plant and the reactor
temperature for the first 35 days of operation. Figure 3 gives the
same information for the succeeding 35 days. As can be seen
from these data, the plant was capable of operation after eight
days when a feed rate of 2.08 g/day/1 was recorded. Reduced
feed rates and failure to feed on days 13, 20, and 21 were due to
pump failure and not to problems in the biological system. The
maximum feed rate recorded during those initial 70 days was
7.26 g/day/1 (or 512.0 kg NO3 per day). Figures 2 and 3 also
point out the wide variation in temperature that has been rec-
orded; these going from an initial temperature of 19° C to a
maximum of 46.5°C.
Figures 4 and 5 give the pH, nitrate concentration, and
organic carbon concentration in the reactor. Since the reactor is
essentially completely mixed, the conditions in the reactor are
assumed to represent that of the effluent solution. The pFI was
controlled well and kept at a slightly alkaline value as it had been
decided to keep the pH of the reactor no lower than 7.0 and no
higher than 8.3. Organic carbon levels were set to be within the
range of 500-2500 mg/1, TOC. The carbon levels were kept well
within these limits, with minor exceptions. Nitrates were to be
kept as low as possible but in no case above 2000 mg/1; such high
levels giving an indication of unsatisfactory reactor operation.
As can be seen from these data, nitrate levels below 100 mg/1
were obtained when the reactor was operating in a satisfactory
manner.
The volume of offgas produced in the reactor was carefully
monitored as well as the percent CO 2in the gas. The volume of
gas produced was deemed to be a measure of the biological
activity in the reactor, and it should be noted that such was
found to be the case. Figures 6 and 7 show these data.
Discussion
Initial operation of the Y-12denitrification facility proceeded
according to plan. After a period of two days following initial
seeding, in which the plant was operated as a batch system,
feeding began. The plant was able to handle substantial amounts
of nitrate (see Figures 2 and 3) once stable operational condi-
tions had been established. Rates as high as 7.26 g NO 3/day/1
have been recorded, indicating that each biodenitrification unit
has the capacity to destroy over 570 kg NO 3 per day, which is
well above the design criteria established for the plant. It is
indeed an observational fact that in the operation of the plant a
wide range of feed rates may be applied without impairment of
the quality of the treatment. Such is in accord with the theo-
retical analysis of the continuous cultivation of microorganisms
discussed by Herbert, Elsworth, and Telling."
Developmental data, as well as the data presented herein,
suggest that the overall nitrate level in the reactor should
normally be less than 100 mg/1. The upper nitrate levelat which
all biological activity will cease has not been determined; howev-
er, laboratory reactors have been operated for short periods of
time at levels as high as 8000 mg/1. On one occasion, the reactor
registered a nitrate concentration of 4585 mg/1 after certain
operational difficulties resulted in high loads of nitrate feed
being discharged (see Figure 4). The reactor, however, recovered
very rapidly and returned within acceptable operating limits in
less than 2 days. Control of nitrate levels in the reactor is affected
by regulating the feed flow into the tank. When conditions
-------
Nitrate, Organic Carbon and pH in Reactor
64 Biological Treatment
8.0
x 7.0
Q.
6.0
^ 3000
cr>
e
c
O
.*-)
- 2000
o
LTi
U
o
u
a 1000
Figure 4:
require it, the flow may be interrupted completely.
The carbon-to-nitrogen ratio is an important parameter that
must be closely controlled at the plant. Although a wide range of
carbon-to-nitrogen weight ratios were used in developmental
study, it was determined that the feed should be adjusted to a
carbon-to-nitrogen ratio of 1.18. Since organic carbon is not
only the carbon source but also the energy source for the
denitrifying organisms, it is important that such be available in
less than limiting quantities to prevent a slow-down of the
biological activity. It must also be kept in mind that since the
principal objective of the plant is to reduce nitrate, organic
carbon, as well as all other nutrients should be present in excess
to allow nitrate to be the limiting factor of the biological activity.
Conversely, the upper limits of the organic carbon levels in the
reactor must be carefully monitored, as it was found during de-
velopment that an excessive amount would inhibit the reaction.
Such were the reasons for indicating an optimum operational
condition of 500-2500 mg/1 TOC in the plant.
Control of organic carbon has not been found to be easy in
actual plant operation. On several occasions, the reactor has
been either carbon deficient or with high TOC values in the
mixed liquor. There have been, however, no serious shocks to
the biological system due to low or high carbon that have
affected the operation of the plant for significant periods of
time.
The measurement of the offgas production has been an ex-
ceptionally useful operational indication of the condition of the
reactor. There appears to be a very good correlation between the
imount of gas produced and the biological activity in the
eactor. For example, the day in which the maximum feed rate
vas given (day 60) was that in which maximum gas production
was recorded. Furthermore, a normal level of 50-60% C02 by
weight in the gas is considered norlevels may be related to high
nitrate levels while low C02 is normally associated with
deficiencies in organic carbon. In observing the flow and C02
level in the offgas, the level of activity in the reactor may be
instantly surmised, as well as the type of problem that may be
occurring.
Low pH values are considered to be highly detrimental. Such
low values may affect the steel tank by inducing corrosion. Ia
addition, development work indicates that biological activity in
denitrification becomes less efficient at pH values below neutral
and, for all practical purposes, ceases at pH 6.4 or below. There
is a tendency for the reactor liquor to drop its pH not only
because of the nature of the feed but because of high CO2 pro-
duction. However, the amount of CaCOjin the mixed liquor
tends to stabilize the pH. As noted in Figures4 and 5, the pH has
been maintained at an acceptable level, although occasional
additions of lime have been required to raise the pH slightly, It is
to be noted that available data, as well as results of the devel-
opment work, point to the fact that denitrifiers are not nearly as
sensitive to high pH levels as they are to low and appear to
operate well at ranges of pH 8.0 and above.
Of concern to the operation of the plant was the possibility
that the presence of molecular oxygen in the tank would inhibit
the proper operation of the reactor. The tanks are carefully
sealed and no oxygen interference in plant operation has been
noted, so oxygen inhibition is no longer considered to be of
significance. Also of concgrn is the possibility of the reactor
organism turning to anaerobic metabolism upon exhaustion of
the available nitrate. Septicity problems, however, have been
nonexistent and are also considered to be of minor importance
-------
Biological Treatment 65
Time, Days
Figure 5: Nitrate, Organic Carbon and pH in Reactor
T1re, Days
Figure 6: Off-gas Output and CO 2 Composition
-------
66 Biological Treatment
Figure 7: Off-gas Output and COaComposition
under the present operational conditions which include continu-
ous monitoring of the reactor liquor,
H is interesting to observe the temperature pattern of the
reactor liquor. Increased operation is reflected in a significant
rise in the temperature of the liquor. These changes in tempera-
ture are due to (a) heat of solution of the feed, and (b) the
exothermic biological reaction which takes place. As indicated
by the data, a high temperature of 46.5°C has been registered
without deleterious effects in the operational capabilities of the
biological mass. It is difficult to know to what level the
temperature of the liquor may rise without affecting the
denitrification process. Reference 6 is noted indicating that
denitrification proceeds at high efficiency at the temperature of
60°C. By observing the pattern of the temperature, it may be
speculated that such temperature may be reached and perhaps
surpassed during the summer months unless measures are taken
to lower the temperature of the liquor, (t is, however, obvious
that low temperatures in the fall and winter will not produce a
significant impact on the operation of the reactor.
From these data, it can be surmised that biological denitrifica-
tion as presented in this paper is feasible and effective. Relatively
few problems have been encountered in the operation of the
reactor as far as the biology of it is concerned. In fact, most
problems have derived from mechanical and "teething" trou-
bles such as the failure of valves and the plugging of pumps. It is
also notable that the reactor appears to be very resistant to
shocks and able to recover and return to acceptable operating
conditions. As a whole, it may be said that initial operation of
the plant was remarkably easy and free of difficulties other than
those induced by mechanical problems.
Time, Days
CONCLUSIONS
Based on the data presented, the following conclusions may
be drawn;
1. The biological denitrification reactor has reduced nitrate to
nitrogen gas with feed rates up to 7.26 g N03/day/l.
2. Startup procedures have been simple and effective with the
biological operation being developed smoothly.
3. The reactor has been resistant to shocks and able to return to
normal operation.
4. Gas flow and gas composition have provided a rapid and
effective way to judge the operation of the reactor.
5. No significant problems have keen encountered with pH
control, oxygen inhibition, and septic conditions.
6. Large amounts of heat are evolved in the process, and
elevated liquor temperatures may be a problem during the
summer months.
REFERENCES
1. Mitchell, Ralph, Introduction to Environmental Microbio-
logy, Prentice-Hall, Inc., Englewood Cliffs, N.J. (1974).
2. Valera, C. L. and M. Alexander, Nutrition and Physiology
of Denitrifying Bacteria, Plant and Soil, 15-.269-280 (1961).
3. Wijler, J. and C. C. Delwiche, Investigations on the
Denitrifying Process in Soil, Plant and Soil, 5:155-169
(1954). '
4. Mechalas, B. J., P. M. Allen, and W. M. Matyskiela, A
Study of Nitrification and Denitrification, Water Pollution
Control Research, Series 17010DRD07/70, pages 2-78,
FWQA, Department of the Interior (1970).
5. Miyata, M. and T. Mori, Studies on Denitrification, J.
Biochemistry, 64:849-861 (1968).
6. Bremmer, J. M. and K. Shaw, Denitrification in Soil, J.
Agricultural Science, 51:40-52(1958).
7. Christianson, C. W., E. H. Rex, W. M. Webster, and F. A.
Virgil, Reduction of Nitrate Nitrogen by Modified Acti-
vated Sludge, U.S. Atomic Energy Commission, TID-
7517, pages 264-267 (1956).
8. McCarty, P. L. and P. St. Amant, Biological Denitrifica-
tion of Waste Waters by Addition of Organic Materials,
Proceedings of the 24th Instrial Waste Conference, pages
1271-1285, Purdue University, West Lafayette, Indiana
(1969).
9. Francis, C. W. and M. W. Callahan, Biological Denitrifica-
tion and Its Application in Treatment of High-Nitrate
Wastewaters, Journal of Environmental Quality, Vol 2
(1975).
10. Clark, F. E., H. C. Francke, and J. W. Strohecker,
Biological Denitrification of Nitrate Waste Solutions, 30th
Industrial Waste Conference, Purdue University, West
Lafayette, Indiana (1975).
11. Herbert, D., R. Elsworth, and R. C. Telling, The Continu-
ous Culture of Bacteria; A Theoretical and Experimental
Study, J. Gen. Microbiology, 14, 601 (1956).
-------
Settleability df Industrial
Wastes and Their
Energy Values C. H. Rhee, I. W. Engineering of Los
Angeles County
Sanitation District
Whittier, CA 90607 and
A. Z. Sycip, University of Southern
California
Los Angeles, California
INTRODUCTION
The primary objective of this research was to investigate the
amount of energy contained in industrial waste solids contrib-
uted by the different types of industries. Five major industries
were selected according to Division D (manufacturing) of the
federal STANDARD INDUSTRIAL CLASSIFICATION
(SIC) Manual1. The industries selected were:
SIC 3471 Metal Plating Industry
SIC 2900 Series Petroleum and Refinery Industry
SIC 2800 Series Chemical Industry
SIC 2000 Series Food Process Industry
SIC 2600 Series Paper Industry
A comprehensive laboratory set-up had been accomplished at
the University of Southern California's Environmental Engi-
neering Laboratory for the purpose of assessing settleability of
the five industrial waste solids and their energy values. It was
aimed to determine the percent of solid settling and energy
values within predetermined schedules. The first experiment on
digestionin August, 1977,ended infailuredue to miscalculation
of feeding rates of each industrial waste solid; however, the sec-
ond and third experiments were accomplished with satisfactory
results. This preliminary research may be able to help paper mill
wastewater dischargers and operators.
Settleability Studies
For the purpose of assessing the comparative settling charac-
teristics of five industrial wastes, each ten analyses data from the
same SIC category were selected. A total of fifty companies'
data from the five SIC categories were obtained through the
actual sampling and analyses, and then one company from each
SIC category was selected as a representative of each SIC
category.
Experimental
As .the control parameters of comparative settling tests for the
different industrial wastes, a uniform temperature range of 15-
17°C and pH range of 6.5-7.0 was maintained throughout the
tests to eliminate convection currents. Fifty liters of industrial
waste to be tested were filled into a 15 cm diameter and 300 cm
high plexiglas column. A schematic of the column is shown in
Figure 1. The industrial wastes in the column were agitated for
ten minutes with 1/10 HP, 1550 RPM agitator.
Since the objective of this experiment was to determine how
much of distinct industrial wastes settles in the simulated
primary sedimentation as close as possible, four separate
settling tests for each selected industrial waste were run with the
following mixing rates:
100% industrial waste and 0% raw sewage
40% industrial waste and 60% raw sewage
10% industrial waste and 90% raw sewage
0% industrial waste and 100% raw sewage
Samples were withdrawn at 15, 30, 45, 60 and 75 minutes
immediately after the agitation in the column was completed.
Sampling at the surface was avoided because the floating
particulates that would normally be removed by skimmers in the
primary sedimentation tank. The withdrawal of 200 ml sample
for the average of two COD tests from each column lowered the
liquid level by 5.7 cm, but it is not likely that this change in water
level over 75 minutes would have any noticeable effect on the
settling in the test column.
Figures 2 through 6 show experimental data for five types of
industrial waste. These figures show experimental data of COD
vs. settling time for all four mixtures of industrial waste with
sewage. The settling characteristics of COD would indicate what
extent of settling behavior of industrial waste was actually
affected by mixing with raw sewage. The raw sludge used in the
mixing was obtained from a typical joint treatment plant which
contained estimated flow volumes of 2.4%, 4.7%, 1.8%, 3.8%
and 8.5% of metal plating, refinery, chemical, food processing
and paper mill wastes, respectively, out of 1.322 * 106 m'/day
(350 MOD) of total influent.
Results
Metal Plating Waste—Figure 2 shows the data for settling
tests on Harlow Plating's waste, which had very low COD of
near 320 mg/1. After 30 minutes settling time, only 22% of the
original COD was settled, and the settling behavior for all dif-
ferent mixtures has not changed significantly.
Refinery Waste—Figure 3 shows the data for the same
settling tests on Gulf Oil-Santa Fe Springs Plant's refinery
waste. This waste also had lower COD than that of raw sewage.
The settleable COD of 100% refinery waste settled within 15
minutes, and the settling tendencies of all four mixtures tended
to intersect at 45 minutes settling time. It was also observed that
only 11% of the COD was settled through the total settling time
of 75 minutes.
Chemical Waste—Samples were obtained from the Los
Angeles Chemical Company, a manufacturer of various chemi-
cals. Figure 4 shows data for COD settling tests. About 28% and
33% of settleable COD were settled within 30 minutes and 60
minutes settling time, respectively.
Food Processing Waste—Samples were obtained from a food
processing plant, manufacturer of bacon and TV dinners, in the
City of Industry, California. The raw food processing waste had
a COD of nearly 2040 mg/1, which is greater than twice that of
the raw sewage sample, and the settling behavior seems differ-
ent from the other wastes. The settling curve for the 100% fo,od
67
-------
68 Settleability
¦ 100% RAW SEWAGE
A 10% METAL PLATING WASTE
* 90% RAW SEWAGE
~ 40% METAL PLATING WASTE
60% RAW SEWAGE
• 100% METAL PLATING WASTE
30 45
TIME, minutes
Figure 2: Metal Plating Waste, COD vs. Settling Time
J 60 cm
i
i
L|5cm
Figure 1. Schematic of Experimental Settling Column
processing waste has a waiting period for settling to begin.
Figure 5 shows that the food processing waste settled only 5%
and 27% within 15 minutes and 75 minutes, respectively.
Paper Waste—Samples were obtained from Sonoco Paper
Products Company. Paper waste had a very high COD of nearly
4500 mg/1 when the sample was concentrated to average
suspended solid of nearly 1289 mg/1. As can be seen from Figure
400
300 0 15 30 45 60 75
TIME, minutes
Figure 3: Refinery Waste, COD vs. Settling Time
6, the settling curves for all four mixtures have similar behavior
as theoretically expected. A rapid initial settling of approxi-
mately 55% was observed within 15 minutes and showed almost
horizontal behavior after 30 minutes settling time.
Conclusions
The removal efficiencies of suspended solids for five indus-
-*
-------
Sett leability 69
0 15 30 45 60 75
TIME, minutes
Figure 4: Inorganic Chemical Waste, COD vs. Settling Time
100% PAPER WASTE
40% PAPER WASTE
60% RAW SEWAGE
10% PAPER WASTE
90% RAW SEWAGE
100% RAW SEWAGE
—•—
—•
A
A
A
—¦—
—¦
D 45
60
7!
TIME, minutes
Figure 6: Paper Mill Waste, COD vs. Settling Time
100% FOOD WASTE
40% FOOD WASTE
60% RAW SEWAGE
10% FOOD WASTE
90% RAW SEWAGE
100% RAW SEWAGE
Table I: Estimated Concentrations of Solid in the Primary
Sludge
) 15 30 45 60
TIME, minutes
Figure 5: Food Processing Waste, COD vs. Settling Time
tries and domestic waste were also determined after 75 minutes
settling time and listed in Table 1. As can be seen from Table I,
the total industrial waste solids settled during the 75 minutes
settling time would be approximately 192 tons/day, which was
equivalent to 45% of the total solids settled in the aforemen-
Industrial and
Domestic Waste
Flow
10^ 1/day
(10 eal/dav)
Avg. 1
Suspended
Solids
m*/l
% Suspended
Solids
Settled in
75 Mln.
Settled
Solids
Ton/Dav
Metal Plating
32.017
<8.459)
92
27.1
.9
Refinery
62.551
(16.526)
58
11.0
.4
Chemical
23.259
(6.145)
364
17.3
1.6
Food Processing
50.316
(13.294)
762
31.5
13.3
Paper Products
112.922
(29.834)
1289
78.3
125.6
Other Industries
151.400
(40.000)
"
"
50.0
Domestic Waste
889.475
(235.000)
3002
80.1
235.5
Industry Subtotal
432.467
(114.258)
192.0
Grand Total
1,321.942
(349.258)
427.5
^Represents en average of 8, 9, 10 or 11 companies.
2Datun was obtained froa Todd, David Keith, The Hater Encyclopedia, p. 332.
tioned sedimentation tank. Furthermore, the solids discharged
by the paper industry would be 125.6 tons/ day, which is
approximately 65.4% or 2/3 of the total industrial waste solids
settled. The total flow volume discharged by the industry was
32.7% of the total flow volume. Tables II, III, IV, V and VI
-------
70 Settleability
Table II: Non-Settleable COD and Their Ratios Metal Plating
Waste (MP)*
Table IV: Non-Settleable COD and Their Ratios Chemical
Waste (( H)*
COD Aft"
r SetLlin
Sanple
rr.in.
1 5 niir:.
30 uin.
45 '¦ - n .
Ml.
75 riin.
TOOfo MP
0 ' 5pw'i.:,f
- 1*1
320
265
2 50
2 50
250
230
a/A
.31
. 4
.43
.51
c2
.hi
'-P
&A Sow.-i-o
_ ' 11>1
775
KGi.
3 70
3 70
365
355
b/ri
. -3
.65
.70
. 76
.75
.73
1""', !'P
00 "y now.'ir-o
_ Icl
915
545
A. 6 5
440
450
UO
c/d
.9 *
. -'9
.00
.93
.91
0'! ;:i
1 00''j Sewap;p
. id1
9 3 0
590
525
U'iQ
4?5
4*5
d/d
1.00
1 .00
1.00
1 ,00
1.00
1.00
' 1
: Art.. ,¦ : m.t ! ;(l,. (.
is ¦ :n.
1. '> .'.in.
('1 ¦ r. ri.
75 r.; n .
1 '
- _ 1 <11
1 J ;
].
1. ¦
•' 1
l . '¦ '
1 .
7 5 '¦
1 , M
755
1 .S3
v ¦ ' ':r
i-l\ !_
! i
> . 1
7 11
1 . ¦'
1 . i 7
1.3 V
U ? J
SlU'li'M
_ _ i'l _ ..
o/.i
1
! : 2
M ')
J.! '3
5lo
1 .or
510
1.1-3
1 1 IVin
_ _ Iril _ ...
d/'l
1 .Of
1 .1.0
M
1 O
y.n.
1.1 ¦:
:A'•
1 (.
495
1.00
- —
MP: Metal Plating
Table III: Non-Settleable COD and Their Ratios Refinery 1 able V: Non-Settleable COD and I heir Ratios Food Process
W aste (R F )* ing Waste (F P )*
COD After Settling Time
Sample
3 min.
15 min.
30 min.
45 mi-n.
60 min.
75 min.
100^ RF
0# Sewage
- ial
560
500
500
500
500
50C
a/d
~61
.39
-97
1 .02
1.04
1.05
40$ RF
60% Sewage
- _ibl
720
605
550
530
525
520
b/d
.73
1.10
1.07
1.03
r»09
1.09
1058 RF
90% Sewage
L*1
390
575
540
525
515
505
c/d
.96
1.01
1.04
1.07
1.07
1.06
0% RF
100% Sewage
_ 1*1
925
570
515
490
430
m
d/d
1.00
1.00
1.00
ti.00
T .00
uoo
COD After Settling Time
Sample
0 min.
1 5 min.
30 min.
45 min.
60 min.
75 min.
100# FP
Ofo Sewage
_ ¦ Ial
2040
1940
1550
1530
1500
1430
a/d
2.10
3.34
2.93
3.06
3.00
2.96
L&& FP
60# Sewage
. M
1460
1230
1010
1010
1010
1010
b/d
1.51
2.21
1.94
2,02
2.02
2.02
10";£ FP
90$ Sewage
. i=i_
1240
750
700
700
700
700
c/d
1.23
1-29
1.35
1 .40
1.40
1.40
0% FP
100# Sewage
- „ 1*1 - _
d/d
970
530
520
500
500
500
1.00
1.00
1.00
1 .00
1.00
1.00
* RF 5 Ftaf inery
show nonsettleable COD vs. settling time for metal plating,
refinery, chemical, food processing and paper mill wastes
respectively. The settled solids in the primary sedimentation
tank are valuable raw material for methane gas generation in the
anaerobic digester. The following section will describe the
competitive production rate of methane gas generated from five
distinct industrial waste solids.
Energy Production
The decomposition of industrial waste solids in the anaerobic
digester is a mass phenomenon associated with the play and
interplay of many different forces, physical, chemical and
biological in origin2. The micro-organisms3 responsible for the
anaerobic digestion of organic matter are acid formers and
* FP: Food Processing
methane formers. The first group consists of facultative and
anaerobic bacteria, and they hydrolyze and ferment complex
organic compounds to simple organic acids, such as acetic and
propionic acid. The second group consists of strict anaerobes
and converts the organic acids formed by the first group to
methane gas and carbon dioxide. The gas production is most
closely associated with the changes in energy content of the
complex industrial wastes. Hence, the general efficiencies of gas
production rate from the different industrial waste solids were
studied in order to find which industrial wastes contribute more
energy values to the publicly owned treatment plant.
Experimental
Five laboratory anaerobic reactors for five different industrial
-------
Settleability 71
Table VI: Non-Settleable COD and Their Ratios Paper Mill
Waste (PM)*
GOD After f.oitlin
¦ T i rr,e
Sample
0 min.
15 rnin.
30 r: i n .
45
60 rnin.
75 rnin.
100# PM
0"£ f)ewap;e
. ial
4315
1965
12 io
1?50
1210
1210
n/d
4. 93
3.M
;v/5
2. 12
2.69
. 69
40^ il-i
60fa Sewape
. i»>i
20 i,L
12
!(¦/~()
(y K)
V6<,
965
b/d
2.33
2.27
2.13
2.14
2.14
ic#
90% Sewai'P
- _ _ _
l2'/u
i}')U
'S)b
5*n
1=70
570
c/d
1 .4!)
1 .22
1 .2-!
1 .26
1 .71
1.27
y/c pm
100?$ flewapio
- idl
tVf>
5o5
405
A 60
4f>0
450
d/d
1 lOO
1 ,u0
1 .00
1 .o0
1 .00
1.00
i'K: I'apor Mil
BELT DRIVEN MIXER
OIL SEAL
|—CONSTANT TEMPERTURE
WATER BATH
mmmM
DIGESTED SLUDGE
TRAP
WE
TEST
METER
Figure 7: Laboratory Anaerobic Reactor Used for Conducting
Studies in Complete-Mix-Batch-Type Industrial Waste Treat-
ment
Table VII: Feed and Digested Sludge Characteristics of Industrial Wastes
Industrial
Waste
Anaerobic
Reactor
No.
pH
COD,
mg/1
*
Solid
Content
1o
Volatile
Solids
Digested
Sludge COD,
mg/1
Digested
Sludge,
f3 Solids
VIetal
Plating
1
7.05
4,100
0.94
34.0
21,100
1.497
Refinery-
2
6.73
400
0.23
17.4
15,700
0.935
Inorganic
Chemical
3
6. SO
31,900
6.15
11.4
1 ,200
0.220
Food
Processing
4
3-94
25,500
6.31
97.0
3,400
0.620
Paper
villi
5
5.35
57,200
4.64
96.3
15,690
1.363
wastes were started from actively digesting sludge taken out
from the anaerobic digester of a typical joint treatment plant. A
schematic diagram of a batch-type laboratory anaerobic reactor
is shown in Figure 7. The units in this system are essentially
complete-mix-no-recycle reactors; therefore, the hydraulic
retention time is maintained by withdrawing a constant volume
from the reactor each day.
The actual proportioned mixing rates of each industrial waste
contained in the primary raw sludge of the aforementioned
treatment plant were calculated, and same rates were applied in
the laboratory reactors. Each reactor was then sealed, gas
collection systems were connected, belt driven stirrers were
started, and the temperature was maintained within a range of
35.0-37.0°C by the constant temperature water bath. Seven
days later the normal feeding procedures were begun and were
continued for 35 days.
As a daily feeding procedure, first the time and gas volume
were read from gas meters and recorded. Then the mixing was
checked. Next, equal quantity of industrial waste fed was
withdrawn from the digested sludge outlet. A funnel was
inserted into the part, and the feed part was opened for the
feeding of industrial waste solids. Table VII shows the feed and
digested sludge characteristics of industrial wastes.
This procedure was repeated for each digester, and the
withdrawn digester samples were analyzed to determine the
characteristics, such as pH, volatile acid, total alkalinity and
-------
72 Settleability
Waste
operating temperature in the reactors. Analyses were per-
formed twice a week. The methane gas produced as analyzed by
the gas chromatographic method4 for the determination of the
percent methane and percent carbon dioxide content, as shown
in Figure 8.
Control of Digester pH — Occasionally, during the experi-
ments, a digester would begin to fail. Because the important
objective of this research was to investigate the comparative
methane producibility from different industrial waste solids
upon anaerobic digestion, the first requirement for maintaining
a balance digester is pH control. Sawyer and McCarty5 have
emphasized that inhibition of gas production begins at pH 6.5
and is complete at pH 5.0. McCarty6 recommends that chemi-
cals be added to keep the pH from falling below 6.5 if it is neces-
sary, and states that the chemicals to use are lime or sodium
bicarbonate. Therefore, whenever the pH dropped below 6.5,
lime was added to bring it back to nearly pH 6.9. The lime will
react with CO2, i.e.,
2C02 + Ca (OH)2 1st reaction^ Ca (HC03)2 (1)
When lime is added to anaerobic digester, the bicarbonate
alkalinity increases initially as shown in Equation 1. However,
an additional lime addition will produce insoluble calcium
carbonate as shown in Equation 2.
C02 + Ca (OH)j *-CaCO3 + H20 (2)
Therefore, an additional lime addition is not beneficial if the pH
maintains above 6.1 to 6.8. The lime addition was not practiced
until the pH dropped below 6.5.
Discussion of Buffer Capacity
Bicarbonate and pH—The major chemical system controlling
pH is CO 2 and HCO3 system, which is directly related to pH or
hydrogen ion concentration. The carbonic acid concentration
(H 2CO,) is related to the percentage of CO2 in the digester gas,
as shown in Equation 36.
H2C03 ^ H+ + HCO3
(H+] [HCO3} =Kj
[H2C03]
Therefore, |H+] = K, [H2CQ3|
[HCOj] (3)
where K. i = ionization constant for carbonic acid. The HCOj
concentration forms a part of the total alkalinity in the system,
and is approximately equivalent to the total alkalinity when the
volatile acid concentration is very low, i.e., when the pH level is
high. When the methane bacteria cannot consume volatile acids
right away, the pH will become lower. As u result, the volatile
acids accumulate in the digester, and will destroy the bicarbo-
nate and increase the COzconcentration, as shown in Equation
4.
CH3COOH + hco"3—»-ch3coo~+co2 + H20
(4)
Finally, if the HCO*concentration decreases below 1,000 mg/ 1
and this phenomenon is not corrected, the microorganisms
cannot be survived7. Therefore, the maintenance of buffer
capacity by adding neutralizing chemicals is necessary.
Results of Gasification
The amount of gas produced, measured in ft1, during each
week was divided by seven in order to find an average gas pro-
duction rate/day, and this value was again divided by the
amount of volatile solid fed to the anaerobic reactor each day.
The quotients obtained by this manner for each industrial waste
were then converted to liter/kg. volatile solid (1/kg. vs.) and
shown in Table VIII and Figure9. From Figure9and Table VIII
it can be seen that the amount of gas produced from all five
reactors was approximately equal as expected since the first
week was considered as an acclimitization period from the
actively digesting sludge and actual primary sludge taken out
from the treatment plant. It was found that the different
industrial wastes had entirely distinct gas producing behavior.
However, the general feature shows that the gas production
from all wastes during the second week has drastically increased
and then decreased gradually during the third and following
weeks except paper waste. The gas producing behaviors for each
industrial waste are discussed as follows;
Metal Plating Waste The sample of this waste obtained
from the Harlow Plating Company contained approximately
100 mg/1 of zinc, 2 mg/1 of chromium, and 10 mg/1 of cyanide.
The zinc and cyanide toxicity have been blamed for many
digester failures unless one mole of sulfide was present per mole
of zinc for precipitation. Since the sulfide was not detected in the
sample, the zinc and cyanide positively caused digester upsets.
The gas production during the second week was almost nine
times greater than that of the first week and showed drastic drop
during the third week, and then approximately 11% and 30%
drops during the fourth and fifth weeks respectively. It can be
predicted that the gas production will reach zero within the two
or three weeks. The gas producing behavior for metal plating
waste is shown in Table IX.
Refinery Waste—The Gulf Oil waste normally contained
approximately 100 to 200 mg/1 of ammonia nitrogen, 1 to 2
mg/1 of thiosulfate, 300 to 400 mg/1 of total hardness, 1 to 2
mg11 of chromium and 80 to 90 mg/1 of phenols. The ammonia
nitrogen analysis gives the sum total of ammonia ion plus
ammonia gas concentration, and if the ammonia nitrogen
concentration is between the 50 to 200 mg/1, the effect on
anaerobic digestion is beneficial6. The gas production during
the second week showed the highest gas production rate among
all of the industrial wastes digested, and showed gradual
reductions of 84%, 71% and 26% during the third, fourth and
fifth weeks respectively. These phenomena probably caused by
the beneficial effect of immediate mixture of ammonia nitrogen
with the digesting sludge and showed adverse effect of high
-------
Settleability 73
10000
CsJ
o
2fx1000
Qlo
^o
3 co
CD
8
.-= 100
o
CLg
-------
74 Settleability
Table IX: Gas Producing Behavior for Metal Plating Waste
Detention
Time, days
pH
Volatile Acids,
mg/1 as acetic
acid
Total
Alkalinity,
mg/1 as GaCO^
Gas
Volume,
Cu. Ft J
0-72
7.32
7.31
1225
3032
1 .410
3-14
7.07
7.35
1350
1008
3023
2959
0.617
15-21
7.00
7.12
1135
1051
2253
2163
0.035
22-23
7.19
7.26
750
576
2102
2196
0.097
29-35
6.90
7.03
1121
1027
2060
2155
O.O46
1 Controlled pH
^Acclimization period
Table X: Gas Producing Behavior for Refinery Waste
Detention
Time, days
pH1
Volatile Acids,
mg/1 as acetic
acid
Total
Alkalinity,
mg/1 as CaCO-j
Gas
Volume,
Cu. Ft.
0-72
7.33
7.25
1264
3570
1 .406
3-14
7.29
7.44
250
72
O^-O
0 0
-4- r~\
1 .466
15-21
7.17
7.29
115
24
2523
2694
0.237
22-23
• •
vn O
100
192
2236
2032
0.071
29-35
7.09
7.14
207
195
1934
.2120
0.053
^Controlled pH
o
Acclimization period
concentration of phenols and the stimulatory effect of hard-
nessft'7. The gas producing behavior for this waste is shown in
Table X.
Chemical Waste—Los Angeles Chemical's wastewater con-
tains 10 to 20 mg/1 of copper, I to 2 mg/i of chlorinated
hydrocarbon and trace amounts of arsenic and heavy metals.
The gas production was sharply increased during the second
week. This decrease was probably caused by the high concentra-
tion of copper, chlorinated hydrocarbons and trace amounts of
heavy metals. However, the sharp increase of gas production
during the second week should be investigated under a separate
research schedule. The gas producing behavior for this waste is
shown in Table XI.
Food Processing Waste—The gas producing characteristic of
-------
Settleability 75
Table XI: Gas Producing Behavior for Chemical Waste
Detention
Time, days
PH1
Volatile Acids,
mg/'l as acetic
acid
Total
Alkalinity,
mg/l as CaCO^
Gas
Volumej
Cu. Ft,
0
0-7
7.19
7.03
1432
2907
1.399
3-14
7.30
7.4^
1000
264
3040
3020
1.394
15-21
7.36
7.31
303
321
2950
2532
O.467
22-23
7.17
7.17
130
120
2204
2234
0.176
29-35
7.05
7.12
193
174
2335
2266
0.072
1 Controlled pH
p
Acclimization
Period
Table XII: Gas Producing Behavior for Food Processing Waste
Detention
Time, days
pH1
Volatile Acids,
mg/l as acetic
acid
Total
Alkalinity,
mg/l as CaCO-j
Gas
Volume
Cu. Ft
0-72
7.23
7.21
1311
3305
1.295
3-14
7.46
7.50
570
144
3300
3164
1.573
15-21
7.53
7.21
146
146
3092
2704
1.565
22-23
7.22
7.13
143
144
2347
2347
1.253
29-35
7.19
7.20
154
150
2360
2405
1.006
1 Controlled pH
^Acclimization period
-------
76 Settleability
Table XIII: Gas Producing Behavior for Paper Mill Waste
Detention
Time, days
pH1
Volatile Acids,
mg/l as acetic
acid
Total
Alkalinity,
mg/l as CaC03
Gas
Volume
Cu. Ft,
0-72
7.34
«¦»
7.33
1446
3552
1.390
3-14
7.23
312
3323
7.41
24
3184
2.045
15-21
7.40
139
3306
6.96
189
2449
1.841
22-23
6.91
150
2041
6.33
144
1373
1.657
29-35
6.74
211
1769
6.76
197
1857
1.729
^Controlled pH
^Acclimization period
Table XIV: Comparative Energy Values Contributed by Industries
Industrial
Waste
Gas Product.
Rate During
Fifth Week,
liter/Kg,vs.
Settled
Solids,
ton/yr.
Total
Gas
Produced
m3/yr.
%
C02
%
ch4
Total
Methane,
m3/yr.
Energy3
Value®
BTU X 10Vyr
Methane^1
Value,
$/yr.
yietal
Plating
335
.9 X 260
73,390
16.2
54.5
42,720
1.509
1,962
Refinery
3,654
.4 x 360
1,246,176
12.2
63.0
347,400
29.926
33,904
Chemical
1,270
1.6 X 260
569,920
20.5
59.0
336,253
11.375
15,437
Food
Processing
1,337
13.3 X 260
6,352,346
23.0
60.0
3,311,403
134.600
174,930
Paper
villi
320
125.6 x 360
14,469,120
43.0
47.0
6,300,436
240.159
312,207
Notes 1. Paper mill and refinery plant operate 36O days/yr. and other industries
operate 260 days/yr.
2. (l/Kg)•(ton/day)•(day/yr)•(1000 Kg/ton)•(m3/i0001) ¦» mVyr.
3. m3 = 35*314 ft3, ft3 of CH4 = 1000 BTU
4. 106 BTU = $1.3
-------
Settleability 77
this waste was different from the previous three wastes. The gas
production during the second week was increased
approximately 5.4 times and maintained the general behavior of
steady-state with slight reductions. The gas producing behavior
for this waste is shown in Table XII.
Paper Mill Waste—The major substrate contained in this
waste was unbleached draft fibers and dissolved starches. The
gas producing behavior was totally different from the other four
industrial wastes. The gas production was reduced
approximately 10 to 15% each week up to the fourth week and
showed approximately a 7% increase during the fifth week. This
phenomenon can be interpreted that the carbohydrate has a
slow rate of anaerobic degradation and will show a tendency of
steady-state. The gas producing behavior for this waste is shown
in Table XIII.
Gas Analyses and Energy Values
Although the metal plating, refinery and chemical wastes
showed decreasing gas production behavior and gas produc-
tion will gradually be leveled off by increasing detention time,
the produced gases were analyzed for percent methane and per-
cent carbon dioxide. Figure 8 shows a typical chromatograph of
digester gas from paper waste. Comparative energy values based
on the results of the fifth week were calculated and listed in
Table XIV,
Conclusions
It can be predicted from Figure 9 and Table XIV that the pa-
per mill waste and food processing waste actively contribute raw
materials for methane gas production. Paper mill waste and
food processing waste produce approximately 320 1/kg vs. and
1800 1/kg vs. of gas without nutrients in the laboratory reactor
while the actual anaerobic digester in a typical treatment plant
produces approximately 1080 1/kg vs. of gas. Although paper
mill waste produces the least amount of gas with the least per-
cent methane, it contributes a maximum energy value to the
publicly owned treatment plant. For example, if a company
discharges 1.14 » 104m3 (3 MGD) of wastewater with 2000 mg/1
of suspended solids, they contribute approximately $43,000/yr.
of energy value without nutrients. These energy values may be
credited in the cost recovery system if it exceeds the fair share of
O & M costs.
Future Research Needs
In order to obtain potential benefits from the energy contrib-
uted, certain technological developments by the paper and food
industries are yet required.
ACKNOWLEDGMENT
The authors wish to thank Dr. John Milne of the Los Angeles
County Sanitation Districts for his technical support and
assessment in the preparation of this paper.
REFERENCES
1. Standard Industrial Classification Manual, Executive Office
of the President of the United States, 1972.
2. Fair, G. M. and Moore, E. W., "Heat and Energy Relation in
the Digestion of Sewage Sludge," Sewage Works Journal,
Vol. 4, No. 3, May, 1932.
3. Metcalf and Eddy, Inc., Wastewater Engineering, pp. 415-
419, 1972.
4. Standard Method, 14th ed., Section 511, 1975.
5. Sawyer, C. N. and McCarty, P. L., Chemistry for Sanitary
Engineers, pp. 479-485, 1967.
6. McCarty, P. L., "Anaerobic Waste Treatment Fundamen-
tals," Public Works, Sept., 1964.
7. WPCF Manual of Practice No. 16, "Anaerobic Sludge
Digestion," pp. 32-35, 1968.
-------
Treatment of Industrial
Wastes from Airport
and Airplane Maintenance—
A Pilot Study
Moshe Uziel and William Strangio
Consoer, Townsend & Associates
San Jose, California
INTRODUCTION
In a major international airport on the West Coast, the
current commercial activities include approximately 342,500
flights per year, 18 million passengers, and 0.5 million tons of
mail and express freight. The industrial activities of the airport
include the maintenance of airplanes, mechanical equipment,
cars from rental companies, and maintenance of the extensive
airport facilities.
The largest domestic carrier in the U.S. has its fleet mainte-
nance base at this airport. Other airlines also have maintenance
activities to various degrees.
All these activities create approximately 1.15 MGD (in dry
weather) of complex industrial waste which is segregated from
the domestic type waste generated at the airport.
During wet weather, the flow can reach approximately 20
MOD. This flow originates as runoff from runways and other
paved areas in the airport. The composition of the initial runoff
is similar to the waste composition. H owever, the concentration
of pollutants is lower and varies as a function of the frequency
and duration of the rain.
The industrial waste contains: oil and grease, jet fuels, acid
and alkaline materials, large amounts of industrial detergents,
organic solvents, ketones, phenols, paint strippers, heavy
metals, cyanide and various other chemical compounds.
Currently, the waste is pumped into a holding pond and then
discharged to San Francisco Bay. The effluent of this pond does
not meet the quality standards as defined by the Federal Gov-
ernment and the State of California.
As a result of previous studies and theoretical considerations,
a system for adequate treatment of the waste was proposed. The
system was to incorporate physical-chemical processes with the
more economical biological processes and consisted of the
following major components: flow equalization, oil separation,
and biological oxidation.
The purpose of the pilot study described in this paper was to
verify the system concept and effluent quality and to refine
design information. The goals were achieved by the operation of
an "on line" 3 gpm pilot plant, which was a scale down of the
proposed plant. The entire project required approximately 4.5
months including about 2 '/2 months of actual operation.
Materials and Methods
The purpose of the pilot study was to find an adequate
method to treat the Airport's industrial waste to a quality that
ts the California State Regional Quality Control Board's
:arge criteria. These criteria are summarized in Table I.
e investigation took place in two parallel avenues:
Table I: Permissible Discharge Concentrations
.U) tJ.I*/ A " i • 1
I'.U 1 /
SO
::u ] i .I'-
ll!; .
n. :•(}
<>. r. o
.. . ....
u . .
0 .lit
— _ ---
"""
u . ID
——
(•' .: : . ' 1
n . l' i
¦ ¦' . -1 0
!' ! J , '
1
;
• Pilot Plant Study
• Examination of the Existing Collection System
Pilot Plant Study
The pilot plant consists of four main unit processes:
Flow and concentration equalization
Flocculation of oils, grease and suspended material
Dissolve air flotation for removal of oils, grease and sus-
pended materials
Trickling filter for reduction of B.O.D., C.O.D. phenols,
heavy metals and detergents
Foam fractionation was also tried for oil and detergents
separation.
The process flow is: the industrial waste was pumped from a
Pump Station approximately 700 feet to the pilot plant location.
There, the waste was introduced into a weir box to control the
flow into the equalization basin. A P.V.C. children's swimming
pool 12 feet in diameter and 3 feet in height was used for
1.
2.
3.
4.
78
-------
A.irport Industrial Wastes 79
equalization. From the equalization basin, the waste was
pumped and metered into the flocculation continuous stirred
tank reactor (C.S.T.R.) which consisted of two 32gallon plastic
containers connected in series with slow mixing in the second
reactor. Before flocculation, Alum was introduced into the
waste stream (chemical pump P4) via stationary, on line, plug
flow mixing reactor. Polyelectrolytes were introduced into the
Dissolve Air Flotation (D.A.F.) open air inlet with chemical
metering pump. The Dissolve Air Flotation Unit had a surface
area of 1 foot2. Air was introduced into the waste by recycling
part of the unit's effluent through a pressurization tank at 70 psi.
From the D.A.F. unit, the waste flowed to a "Retention Basin"
for hydraulic control and to reduce the number of pumps
required. From the retention basin, the required amount of
waste for a given experiment was pumped to the trickling filter
with a variable speed pump.
Since the waste is low in ammonia nitrogen it was supple-
mented to provide a "balance diet" to the microorganisms in the
Trickling Filter. Ammonia nitrogen was supplemented in the
form of NH4C1 and metered into the waste stream by chemical
feed pump and a plug flow mixing reactor. The Trickling
Filter consisted of Superstrut steel structure about 22 feet high
with Actifil (No. 01 0370 Plastic Bioring) plastic media. Surface
dimensions of the filter were 20" * 20" and the filler had a depth
of 17' 8". The media was enclosed in !4" plywood walls. The
Trickling Filter was equipped with sampling valves at the
following points from the top: 4' 6", 9' 2", 13' 3". Samples were
also collected at the bottom of the filter. A second plastic
swimming pool served as secondary clarifier. It was designed to
have variable hydraulic detention time as selected for given
experimental conditions. Flowever, during the study, it was
found that this unit was not necessary since the trickling filter
produced a perfectly clear effluent (1 to 5 J.T.U.) without
clarification as there was no sloughing of growth from the filter
media.
The foam fractionation unit consisted of a rectangular box 2'
wide, 4' long and 8' tall with underflow buffle at the effluent end,
and 3' of ceramic diffusers (the Norton Co.) at the reaction
compartment. The air was supplied by a 5 B.H.P. Blower cable
to produce maximum air flow of 100 scfm at 7 psig, at sea level
elevation. The amount of air (volume and pressure) was
controlled by a vent at the discharge side of the blower.
Initially, the major tasks in starting the pilot plant were to find
the appropriate operating conditions for the D.A.F. unit, and to
establish growth on the trickling filter. The optional chemical
dose for dissolve air flotation was determined by laboratory and
field studies.
The initiation of microorganisms growth on the trickling filter
followed the methodology described below: The trickling filter
was operated as a batch culture in a closed loop. Media was
prepared in a 32 gallon plastic container and continuously
pumped on the trickling filter. The effluent from the filter
returned to the container for repumping. The filter was inocu-
lated with microorganisms obtained from the Trickling Filter at
the City of San Carlos sewage treatment plant. Microorganisms
were collected by scraping filter media stones, collecting filter
effluent, and placing a few stones with the microorganisms on
top of the experimental filter and inside the 32 gallon container.
The San Carlos Trickling Filter was selected since it receives
industrial waste with relatively high amounts of heavy metals
and solvents. Because of the limited time available for this study,
the following methods were used to optimize, and therefore
accelerate, the establishment of growth on the Trickling Filter:
• Use of defined nutrient media
• Use of gelatine for coating of the trickling filter plastic
media with polymeric layer to help bacterial attachment
• Use of eggs protein to provide the media with polymeric
attachment coating, which is also a nutrient and source of
amino acids
• Aerobic and anaerobic bacteria were introduced in the
form of: pond effluent, secondary sludge, (both trickling
filter and activated sludge), and anaerobic sludge
• The trickling filter culture was conditioned to the industrial
waste by gradually increasing the waste concentration and
by "shock loading of the filter" to enrich for efficient and
adaptable microorganisms
After the start of the experiments, the Trickling Filter was
operated continuously for more than two months. During the
last experimental stage, the filter was attended for 24 hours per
day and composite samples were collected.
Examination of the Existing Collection System
The existing collection system was examined visually for its
transport of suspended matter, and flotables during dry and wet
weather.
Results
Table II presents summary of BOD, TOC and COD of the
waste with and without its oil content. Table III summarizes the
results of preliminary investigations with Dissolve Air Flota-
tion. Table IV summarizes performance that can be expected
from an API separator.
The industrial waste is very low(l~mg/l) in ammonia
nitrogen. For proper operation of a biological system, this form
of nitrogen has to be added to the waste to provide a "balanced
diet" for the microorganisms. The least expensive source of
ammonia nitrogen is anaerobic digester supernatant. The
supernatent of anaerobic digester at the airport domestic waste
plant was analyzed (Table V) to provide design information for
the nitrogen supplementation system.
Table VI summarizes the mean pH and dissolve oxygen
content of the process streams. Table VII presents a summary of
COD reduction as function of depth in the trickling filter.
Table VIII shows the progressive reduction in turbidity after
each unit process in the pilot plant.
Chemical doses used in the pilot plant were as follows:
Ammonia Nitrogen—15 mg/1
Aluminum Sulfate—100 mg/1-150 mg/1
Cationic Polyelectroyte—1 mg/1
Discussion
Visual Observations of the Industrial Waste and the
Collection System
During this study, the industrial waste was examined
continuously for its appearance. The color of the waste changed
from gray wash-water to green-brown plating mchine shop type,
or oil black. Most of the oil was usually well emulsified by the
detergents and solvents in the waste. From time to time, a large
amount of free floating oil appeared in the collection channels.
However, most of this oil was progressively emulsified as it
traveled down stream. This observation agrees with the chemi-
cal analysis, that shows that most of the oil in this waste is
emulsified, as discussed later. In general, the waste had an oil-
gasoline type of smell but at times the smell changed for a short
time to a heavy smell typical to concentrated municipal waste.
The waste had little or no floating materials.
The collection system's open channels are coated with heavy
black oil sludge on the sides and bottom. It was observed that
the continuous flow of industrial this waste over the sludge, at
the bottom of the channels, causes continuous erosion and
releases of soluble oils into the waste (and probably heavy
metals also). This will happen as a result of chemical equilibrium
-------
80 Airport Industrial Wastes
and mass action phenomena. Mass transfer from sludge
sediments into the industrial waste occurred especially when the
waste was relatively clean from oils, but rich with acids,
solvents, and detergents. The existing collection system is a
degenerative system that increases the waste toxic characteris-
tics and inhibits its treatability by physical and/ or biological
means. Sedimenting materials should not be allowed to settle in
channels and sewers, they should be transported to a treatment
system where they can be easily removed.
Table II: Analysis of the Industrial Waste After Equalization (Pilot Plant Influent)
Da te
BOD mg/1
TOC
HKj/ 1
COD
mg/1
A f I o r
Oil Kxtiac(ion
Total
BOD s
U1 t ima te
BOD u
Filtor-
lblc-COD:
Total
TOC
Filter-
able T.O.C
To ta 1
!'i 1 to r ¦
a b 1 e
BOD
r'v-;/1
TOC
:ik;/1
COD
m f; / 1
12/15/76
135
14 5
90
5 3
40
4 4 8
2 32
-
-
-
12/16/76
130
14 1
78
4 9
4 1
4 4 4
243
-
-
_
12/17/76
690
1770
9 30
353
5 54
3 8 tj 0
2 7 1 0
6 6
-
22 3
12/20/76
163
204
97
67
52
5 0 2
3 3 1
/ 4
-
2 C 3
12/21/76
300
417
248
124
102
956
749
6 9
-
3 4 3
12/22/76
4 8
53
21
45
17
16 1
98
-
-
-
12/23/76
330
350
7 3
337
5 2
1 0 < • 0
2 7 4
4 [)
:s i
: c:
12/27/76
190
238
89
116
6 4
6 T. j
2 6 7
4 0
53
18 8
12/28/76
156
217
93
6 o
54
5 1 2
2 96
5 5
44
24 0
12/29/76
72
90
3 6
4 0
17
24 6
1 3 1
12
2 4
1 2 9
12/30/76
4 3
-
-
-
-
2 6 6
1 39
1 5
2 34
Moan
205
362
1 76
125
99
8 8 9
4 ') 7
4 8
.5 8
2 2 4
Standard
Deviation
185
507
272
119
162
10 7 4
75 4
24
13
63
BOD u
BOD i
1.77
Range
4 3-69 0
53-1770
21-930
40-353
17-554
161-3860
98-27 10
15-66
24-53
139- 34 3
Table III: Preliminary Pilot Tests with Dissolve Air Flotation
Run
No.
GPM
°R
Chem
Flow
Oil
and Grease
C.O.D.
M.B.A.S.
GPM
Dose
Type
" C"
- '.C 5
% AC
C
-AC
S.AC
C
-AC
%AC
in
r-H
TJ
u
1
1
3
3
1
1
0
0
Inf. 1
Eff. 2
1 76
54
122
69
338
308
26
8
7
4
3
43
•H
E
0)
jC
)
2
2
3
3
1. 5
1.5
0
0
Inf.
Eff.
812
20
792
98
308
290
18
6
5
6
0
0
0
z
3
3
3
3
2
2
0
0
Inf.
Eff.
340
47
293
86
300
296
4
1
7
4
3
43
£
4
4
3
3
1
1
Alum 1
Alum 1
Inf .
Eff.
74
54
20
27
272
276
0
0
8
8
0
0
i—<
<
5
5
3
3
2
2
Alum1
Alum1
Inf .
Zt.
89
17
72
81
272
248
24
10
12'
4
8
67
X. Inf. = Influent 2. Eff. = Effluent 3. Alum Dose = 103 mg/1
4. C = Concentration in mg/1 5.ftC = Chanye in C 6. No Flocculation
of Alum before the Dissolve Air Flotation Unit
-------
Airport Industrial Wastes 81
Table IV: Common Characteristics of Refinery API Separator Table V: Analysis of Digester Supernatant
Effluents
Run^ e in
K anj;o ln
< 'oiw . of
( 'c )IU' . ol
Refinery
Oil and
Tola] Orj»
Subcategory
Crease
(.la r 1 mn
m ^ /1
inj1/]
A - Topping
10-50
1 0-50
R - Cracking
] S-300
50-500
C - Petrochrinicril
20-250
100-250
D - Lube
-10-400
100-4 00
E - Integrated
20-500
50-500
Digester
Constituent
Primary Digester
Concentra t; ion
IW|/ I
Secondary Digester
Concentration
in<)/1
Ammonia Ni troqen
4 R ft
20 7
n°2"
0. 2
0. 5
N03~
<0.1
¦'0.1
TKN
1210
5 80
BODr
j
2690
1 690
COD
21100
R 4 5 0
TS
17100
6620
"Development Document for Affluent Limitation ("i n ictel in es and New
Source performance Standards fur Petrol mim Ueiiin'iy Point Source?
Category,'1 KPA , Washington, D.C., RPA - 4*1 0/ 1 - 7 1 - 0 I I-a , April
197-1 .
Table VI: pH and Dissolve Oxygen of Process Streams
Statistical
Variable
Para-
meter
In i 2 1
Wa s to
Inf lv.ent1
F'lorculation
Basi n
D.A.F.
Eff.
T.F.
Kff .
'He
Mi ,Cl
r- 1 ** , '
T-o 1 ul l on
}. I \:m
Poly;:,or
Solui ion
M« in
pH
7 . 03
5.8
b. r:> S
0.78
4.0
S. 7
;. o
4.7
D.O.
2. f»0
6. GO
O . 70
-
-
-
Standard
PM
0. 17
0
0.35
o o
0
0
0
0
Devi at i on
D.O.
1 .-10
-
0.:: A
0.16
"
"
1. After EquaJization Basin
Table VII: Experimental Results COD vs Depth in Trickling
Filter
Run No.
Deptli in Trickling Filter CM
0
279
404
538
1
120
110
80
80
2
120
90
80
90
3
120
80
80
60
4
120
70
70
70
5
100
90
90
90
6
110
80
80
80
7
150
100
90
90
Table VIII: Pilot Plant Results Reduction of Turbidity1 in the
Treatment Process
Turbidity
Run No.
Sample
J.T.U
o Reduction
I n f 1uen t
140
1
oaf
77
4 5
TF Eff.3
1.6
99
Influent
140
2
DAF Eff.
34
76
TF Eff.
4 . 5
97
1.
2.
Turbiditv is in direct proportion to suspended
solids concentration.
DAF Eff. = Effluent from dissolved air flotation
uni ts.
3. T.F. = Effluent from trickling filter.
4. Turbidity standard for drinking water = 5 JT
unit 1 J.T.U - 1 mg/1 at low concentrations
-------
82 Airport Industrial Wastes
The Pilot Plant Study
Equalization: Flow and concentration equalization of 4 to 12
hours were examined. In all cases, the physical and biological
units downstream functioned normally. Toxicity to the trickling
filter was not observed. The mixing of the equalization basin
was found to be of importance for good concentration equaliza-
tion.
Oil Separation
The industrial waste is rich in detergents and organic solvents
and therefore the oilsare well emulsified. Dissolve Air Flotation
was selected as the oil separation unit process for the pilot plant.
However, other oil separation methods were examined in an
attempt to isolate a better and more conomical unit process for
final design. Since an API separator was recommended by
others as a pretreatment step before a biological system, this
possibility was examined closely.
Theoretically, an API separator can remove oil droplets of
diameter greater than 150 microns. There are relatively few oil
droplets of this size in an oil emulsion and most of the emulsified
oil will not be removed by this device. Neill and Gloyna "
indicate that an API separator effluent (treating non-emulsified
oil) can be expected to contain 25 -40 mg/1 of oil and can contain
more than 100 mg/1 when overloaded. Table V shows common
effluent characteristics of an API separator treating non-
emulsified effluents. This information points out that oil
concentrations up to 500 mg/1 can be expected in API separator
effluents.
Actual experimentations with gravity oil separation from the
airport's waste are shown in Table IX and Figure I. Table IX
shows mean values of several experiments. Gravity separation
removes 78 81 percent of the free oil but only 5-21 percent of the
emulsified oil. This means that emulsified oil separation is 4-18
times less efficient than free oil. Using these ratios and the theo-
retical information presented in Table V, (E Type-Integrated),
one can expect the minimum oil concentration in an API
separator effluent to be about 80 mg/1. This concentration is
toxic to biological systems. Figure 1 shows actual results of
gravity oil separation from the airport industrial waste. After 2
hours of gravity separation, the oil concentration in the waste
ranged from approximately 50 mg/1 (COD > 200 mg/1) to about
550 mg/1 (COD~900 mg/1). Figure 1 also illustrates that in
most of the cases, the oil concentration after gravity separation
is greater than 200 mg/1. Since about 50 mg/1 of oil is toxic to
biological systems and most of the oil is emulsified most of the
time, gravity oil separation (API) is not recommended as a
pretreatment step before a biological system.
Preliminary tests with foam fractionation found this method
to be inadequate.
Screening tests with the Dissolve Air Flotation Unit (Table
IV) showed satisfactory and reliable oil removal (69 percent to
89 percent) without the addition of chemicals, and approxi-
mately 43 percent removal of detergents. When alum and
polyelectrolytes were added during the pilot plant study, 90 per-
cent of the free oil, up to 77 percent of the emulsified oil and
approximately 67 percent of the detergents were removed. The
oil removal was accompanied by 45-76 percent removal of sus-
pended matter as can be seen in Table IX and Figure 3.
Laboratory investigation showed that appropriate alum dose
was about 110 mg/1, and that about 1 mg/1 of high molecular
weight cationic polyelectrolytes (Hercules) accelerated flock
formation. The Dissolve Air Flotation produced non-toxic
acceptable effluent that was amenable to biological treatment in
the trickling filter.
[ able IX:% Oil Reduction by Gravity Separation (API) and
Dissolve Air Flotation
Typo of nj
nmul'it f )<•¦•! m i
*At Iniqr •.I;'!!-, wti'-n ("i i!) 1 (I" n i • I /
Biological Treatment with A Trickling Filter
The main goal of this pilot study was to examine the ability of
a trickling filter process to treat the airport's industrial waste.
The reduction of C.O.D., B.O.D., oils and grease, detergents,
phenotic compounds, and suspended solids in the trickling filter
were examined. The results of this investigation are summa-
rized in t ables VII through IX, and Figures 2 through 1.
As can be seen from this data, the trickling filter in its optimal
operating condition produces an excellent effluent. The effluent
of the filter meets or is of better quality than required by the
California Regional Water Quality Control Board.
Figure 2 presents data that is used for design of an optimal size
trickling filter. It shows the reduction ofC.O.D. and B.O.D. in
the filter. At a depth of about 300 cm, the removal efficiency of
the filter is substantially reduced. However, this depth was
found to produce effluent of acceptable discharge quality.
Visual examination of the growth on the trickling filter media
revealed the following: low growth at the top I foot of the filter.
Then the growth rapidly increased to such an extent that the
sampling port at a depth of 137 cm (4.5 ft.) was continuously
clogged by biological growth. The biological growth was
reduced at a depth greater than 300 cm.
Figure 3 illustrates the reduction of suspended solids in the
dissolve air flotation and the trickling filter which produces a
clear and sparkling effluent (Figure 7 ). The turbidity in the
effluent is below State limitations. Figures 4 through 7
illustrate the progressive reduction in C.O.D., phenols, oil and
grease and detergents (M.B.A.S.) through the pilot plant unit
processes. It is obvious that at optimal operating conditions of
the trickling filter (QR = 2Q) the effluent quality meets the
discharge limits. These treatment results obtained in the pilot
plant are in agreement with theoretical considerations and
practical experience documented in the literature.
In addition to excellent chemical quality of the trickling filter
effluent, the effluent clarity and color were almost comparable
to that of potable water. This is illustrated in Table IX and
Figure 3.
Removal and Toxicity of Heavy Metals
As a result of waste equalization during the operation of the
pilot plant, we did not observe heavy metals or other toxic
effects on the trickling filter. This agrees with the analytical data
of the industrial waste.
The previously described treatment process is not designed to
remove heavv metals. However, most of these metals are
-------
000
.500
.000
900
800
700
600
500
400
300
200
100
0
1; Pih
Airport Industrial Wastes 83
UP TO 3860 MG/L
A
KEY
C.O.I). OF WASTE
C.O.D. AFTER 2 HOURS
GRAVITY SEPARATION A.P.I.
C.O.D. AFTER OIL EXTRACTION
15 1G 17 20 21 23 27 28 29
DATE IN DECEMBER 1976
Study—Oil Separation C.O.D. of Waste after Various Degrees of Treatment
-------
84 Airport Industrial Wastes
Table X: C oncentration of Metals in Biological Treatment—
Microorganisms
Element
M i o roorcj.i n i ::ns I'roui Uiofilter
(Aerobi t;)
Ma C) ooi 1
'.:d
CI)
CD
Cr
1')
i
i'J
89
Mr;
0. i
0 . 4
2 . 5
G 7
Fc
5
2
1 1
8 8
Co
G
1 1
1 7
9 rj
Ni
1 1
J 1
9
A . 5
Cu
7 3
3.3
1 2
7
7r\
00
1 9
1 1
9
1 Ig
2 7
10
7 . 5
17
Pb
71
25
14
9
As
1 20
195
17
3
Aq
-il
91
?.r>
11
Cd
l :\o
28
9
9
Ti
1 3 J
24
9
A
Sn
SITU)] 1
51
10
13
Sr
smal I
1, Media: Microorganisms that were scraped from the
biofiltcr stationary growth media
Secondary sludge sloughed natura11y from
the Trickling filter media
2. Clarifier:
, . _. ,r , Concentration in the Microorganisms Olio
3. Concentration Deferential - co"nc3nt>'.~F:Tr~o'~Stion '
Table XI: Analysis' of Ash from Incineration2
(Vinci ¦ 111 1 ,i : 1 I )[|:; in ] \i M :: : •, ; •; 1 ; ; , , ,
Mm rch
Vt n!..-!
: '.) 71,
),
!¦: 1
V.i 1 1
] U • ¦. •, !
An i :n< ;ny
1 •;
tin 11
1 'i
/ ,ii
>1
(\-uin. i
('(?•- i 1 ii;i
1
1
coin. 1 :
:> in
i',I
CoPU'./ ]
9 (>')<)
7 -1 M ]
'C i w '11
On ! i i ;j:ii
2'!(<
(K,
l«,.;
f'lO 1 Ll
•'.(!
[I,. !'ni c::i
U
h .
1
«!ooo
1 H00
1 J [ W 1
M.iiv i a :v
'>;•{ o
r» h i)
t. tr>
Mo 1 yink'num
r;
? ;
: i i c o)
1 1 0 ("1
l von
J •: Of;
:: i
1 7
zo
fMl :-i«l i-tin
4-.S
r.cai'u.l i m;ii
•1
V \
]v«m-
(> H)
r,s:o
St ron t. i inn
¦1 a n
•1 in
¦i ' > ' >
To 1 ] u r i unt
fi
H
i
Thori
¦1
c,
r
T i.n
10 00
31 0o
;n',D
I.Iran i u:i>.
]
I i
12.S
Vurunj.i 11!>i
¦10
4 1
¦; o s
V11 r j ti i l
H
')
u. s
Zinc
3 a o o
2 0 0 0
TMJ0
7, i rcon i un.
l*, 0
2 7 0
;0'J
Analysis by: N. Rait dnd K, Cu 1 lirandsen U.S.G.s
Wfcnlo Park., California
Tncinceration of activated sludge from the Wat«r
Pollution Ccnfrol PI art", City of Pdlo A M Oy
Ca1i fornio.
removed in the dissolve air flotation unit and the trickling filter.
In the D.A.F. process, some heavy metal ions attach them-
selves to the charged surface of the alum-oil flock and the
detergents foam. Others are dissolved in the oil and grease. All
these heavy metals are removed in the sludge produced by this
unit process.
Heavy metals are also removed by the trickling filter.
Theoretically, heavy metals toxicity is a result of concentration
and accumulation of those ions in the biological cells. When the
concentration of these metals do not reach toxic levels (Table
XIII), the living cells can tolerate them. Then, the biological
concentration process can be considered as a removable mecha-
nism. This transfer of heavy metals from the effluent into the
sludge results in a cleaner effluent. The concentration phenom-
. described above was documented by the water pollution
itrol plants of the City's of San Carlos (Trickling Filter)and
Palo Alto (Activated Sludge), California. The information
which documents this phenomena is documented in Tables 11
and 12. (Private communications with J. Bewley, City of San
Carlos; and Ray Remmel, City of Palo Alto). Mass balance
reveals that the trickling filter sludge is not expected to cause
toxicity in the anaerobic digester.
As a result of this pilot study, we recommend the treatment
process described in Figure 8.
BIBLIOGRAPHY
I. "Environmental Chemistry Air and Water Pollution," H. S.
Stoker, S. L. Steager. Scott, Foresman and Co. Pub
(I07T\
-------
Airport Industrial Wastes 85
100 ;
90
0
1 30
b-t
K 70 -
u
o
vj
60 -
io J-
G PM
CO = 2.813 ^
-O O- IQ = 3. 750
GPM
Ft7
—O
100
2 00 3 00 ;oo
TRICKLING FILTER DHPTII CM
i00
6 00
Figure 2: % Remaining COD & BOD vs. Depth in the Trickling Filter
2.
t-. 7 5
•AFTKk DISSOLVE AIR FLOTATION
¦ AFTKR TRICKLING FTLTKR
8.
10.
11.
12.
13.
14.
Figure 3: Reduction of Turbidity in the Treatment Process
"Process and Economic Considerations of Ponds for the
Treatment of Industrial Wastewater," Davis L. Ford,
Ph.D., P.E., L. F. Tischler, Ph.D., P.E., Conference on
"Ponds as a Wastewater Alternative," July 22-24, 1975,
Center for Research in Water Resources, the University of
Texas at Austin.
Above conference proceedings.
"Biodegradation of Oil in Ponds," Technical Report
EHE-70-17, CRWR-64, S. Harutunian, E. F. Gloyna, the
U niversity of Texas at Austin (1970).
"Water Quality Engineering for Practicing Engineers," W.
W. Eckenfelder, Jr., Barnes & Nobel, Inc. (1970).
"Wastewater Engineering," Metcalf and Eddy, McGraw-
Hill Book Co. (textbook) (1972).
"Solar Radiation Tables," Algae Research Project, Sani-
tary Engineering Research Laboratory, Department of
Engineering, University of California, Berkeley, June 15,
1974.
"Engineering Management of Water Quality," P. H.
McGauhey, McGraw-Hill Book Co. (1968).
"Biochemical Engineering," S. Aiba, A. Humphrey, N.
Millis, Academic Press, Inc. (1973).
"Preliminary Design Study Industrial Waste Treatment
and Collection Facilities,". Airport Commission, City and
County of San Francisco; Consoer, Townsend & Asso-
ciates, Consulting Engineers (1973).
"Supplemental Preliminary Design Study, Industrial
Waste Treatment and Collection Facilities for San Fran-
cisco International Airport, Airport Commission," Con-
soer, Townsend & Associates, Consulting Engineers (1974).
Report to SFIA Airline Policy Committee on Alternative
Systems for Treatment of Industrial Wastewater, July,
1975, Metcalf and Eddy Engineers.
"Effects of Oil on Biological Waste Treatment," G. H. Neill
and E. F. Gloyna, Technical Report to the Federal Water
Pollution Control Administration, 5T1-WP-183-02
(1970).
"Anaerobic Decomposition of Oil in Bottom Sediments,"
T. B. Shelton, J. V. Hunter, Journal of Water Pollution
Control Federation, 47, 2256(1975).
-------
86 Airport Industrial Wastes
Figure 4: Results of Pilot Plant Study COD Concentration vs. Experimental Day
15. "Integrated Algal Bacterial Systems for Fixation and
Conversion of Solar Energy," Moshe Uziel, W. J. Oswald,
C. G. Golueke. Presented before the Annual Meeting of the
American Association for the Advancement of Science;
Section, "Energy: New Sources"; January 29, 1975, Ameri-
cana Hotel, New York City, New York.
16. "Statement Opposing Provisions Pertaining to the Napa
River in the Preliminary Interim Water Quality Manage-
ment Plan, San Francisco Bay Basin," W.J. Oswald, Ph.D.
Presented before the California Regional Water Quality
Control Board, San Francisco Bay Region, at Kaiser
Center, 300 Lakeside Drive, Oakland, California, May
11-14, 1971.
17. "Relationship Between BOD Removal and LAS Detergent
Removal," Ning Hsi Tang, Puerto Rico University, Maya-
quez. Water Resources Research Institute.
18. "Utilization of Trickling Filters for Dual Treatment of Dry
and Wet Weather Flows," Killam (Elson T.) Associates,
Inc., Milburn, NJ. Peter Homack, Kenneth L. Zippier,
Emil C. Herkert.
19. "Methods for Improvement of Trickling Filter Plant
Performance," North Carolina University, Chapel Hill.
Wastewater Research Center. James C. Brown, Linda W.
Little, Donald E. Francisco, James C. Lamb.
Application of Second Order Reaction," Cornel Univer-
sity, Ithaca, N.Y. Dept. ofSanitary Engineering. VaughnC.
Behn.
21. "A Study of the Effect of Sewage Distribution on High Rate
Filter Efficiency," Public Health Service, Cincinnati, Ohio.
Water and Sanitation Investigations. W. Q. Kehr, C. C.
Ruchhoft, W. Scott Johnson.
22. "Design Guides for Biological Wastewater Treatment
Processes," Texas University, Austin. Center for Research
in Water Resources. Joseph F. Malina, J r. Rolf Kayser, W.
W. Eckenfelder, Jr.
23. "Design Manual for Upgrading Existing Wastewater
Treatment Plants," Roy F. Weston, Inc., WestChester, Pa.
P. Krishnan, C. M. Mangan.
24. "Planning, Development and Management of Wastewater
Treatment Facilities," Training Manual. Environmental
Protection Agency, Washington, D.C. Office of Water
Programs.
25. "A Literature Search and Critical Analysis of Biological
Trickling Filter Studies—Volume II," Dow ChemicalCo.,
Midland, Mich. Functional Products and Systems. Water
Pollution Control Research Series.
26. "A Litearture Search and Critical Analysis of Biological
Trickling Filter Studies—Volume 1," Dow Chemical Co.,
Midland, Mich. Functional Products and Systems. Water
Pollution Control Research Series.
27. "Fate of Cyanide and Related Compounds in Industrial
-------
Airport Industrial Wastes 87
0 . 0 0 -
J. ^
0. ;00
o. ? n o
o. 100
o
0
Figure 5: Results of Pilot Plant Study—Phenols Concentration vs. Experimental Day
:,61 1
!'FI'i,;:iok i;o'.;ali :;ation pas in
LXPLRIMLN'TAL
DAY NO.
z
O
§ 32i
z
W I
u 2.6 -
O
Kj
Ui -J
m " '
<
UJ
16 •
GpM
0 ^ :::KLur:;T flow -/.-7
OR - RiXYCLH FLOW IN
TRICKLING FILTER
ati: of cAL'JP^r.:-:iA
DISC-iAPGI-:
0 = 0.SG3 OR 0 Q = 0.338 OR - 0 Q = 0.333 OR = 2Q Q = 0. 4 5 0 QR = 20
r.KuL i.-. i i ^
r:-:?ERi.v*::-'TAL
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 DAY NO.
Figure 6: Results of Pilot Plant Study—Oil and Grease Concentration vs. Experimental Day
-------
88 Airport Industrial Wastes
: CXPERiMf.::TAL DAY No.
r, P
Q lu(.nt Flow qr - Recycle Flow in Trickling Filter
Figure 7: Results of Pilot Plant Study—MBAS (Detergents) Concentration vs. Experimental Day
¦!T
¦-NM.
.<.* —x ;,
¦ H r I UN ! M
'im 11
A i
hvh. ro
HUMi-b lONJKnl.
SYSTEM)
tvil,;
hun t «h.y «.Ait (.
VAl.Vf HJK OPtN ' r
UlANNLJ. OH j
BlirriKKtV VALVE :
Mix PtUiSSUKK j !
FUJU t
pO.sTKI KUbK (i.PHONAL)
su"""tD
SKIM
' • .-UlSMUVt A IK ¦
I . / FLuTA'l ION
-KLUCCULATION 1ANK • J_
. j "
'i -fi:< i
¦Oi'jj <" -
-'SI
.1. ^ t,.,/
m.l>" '* V
PUMPS I I H1XI W>
U* ~ ' (mi:i I:«,)
r-pol VMhK SY:> I KM
I MLM —" -
l>«tHk.STH PLANT
!! a
_L' ¦
r. i
/
' ;[ kfriuHn
" /'
f
i-K.!.
IIUHA1II l.iJNTfcOL SH.NALS MIXING j
INiJHi.ANIi:
luSb (AlUM)
OPTIONAL UPF'HA'IIUN
CAN I'M KXl;.l INI.
SYSILM IS THE
TKEATMLNT PL.AN1
AI.TEK.4AT1 VE A. ! ALTEHNAIIVf 8,
i.KAVIH > Li*
[X] VA1.VE
c=t HHU HLAMKLMENT lifcVU'E
_0
fafcil S.LUU.E I'l'MP (COS I flVF lilSPI-At I MEND
f Pli.E>
Figure 8: Industrial Waste Treatment Process Schematic Flow Diagram
Waste Treatment," S. F. Raef, W. G. Characklis, M. A.
Kessick, C. H. Ward. Rice Univ., Houston, Texas.
28. "Slime Holdup, Influent BOD, and Mass Transfer in
Trickling Filters," Bernard Atkinson, John A. Howell
University of Manchester Inst, of Science and Technology,
England.
"Treatment of Packinghouse Wastes by Anaerobic
Lagoons and Plastic-Media Filters," Darrell A. Baker,
Allen H. Wymore, James E. White. Farmland Foods, Inc.,
Denison, Iowa.
30. "Carbon Oxygen-Nitrification in Synthetic Media Trick-
ling Filters," Richard J. Stenquist, Denny S. Parker,
Thomas J. Dosh. Brown & Caldwell, San Francisco,
California.
31. "Trickling Filter Versus Activated Sludge: When to Select
Each Process," Don F. Kincannon, Joseph H. Sherrard.
Oklahoma State University, Stillwater.
32. "Trickling Filter Performance as Related to Media Surface
Area," Echol E. Cook, Murry L. Fleming. South 111.
University, Carbondale.
-------
Airport Industrial Wastes 89
33. "Sewage and Storms Get the Full Treatment," Robert J.
Ganley.
34. "Restoring A Dead Trickling Filter," R. S. lngols, W.
Schwenk.
35. "Performance of Plastic Medium in Trickling Filters," M.
J. Gromiec, J. F. Malina, Jr., W. W. Eckenfelder, Jr.
University of Texas, Austin.
36. "Experiments in the Biological Purification of Petroleum
Refinery Waste Water," Ad Strom, lp Danilevskaya, Rp
Ptitsa, Vk Gudym.
37. "Comparison of Stone-Packed and Plastic-Packed Trick-
ling Filters," B. A. Wing, Wm. Steinfeldt, Eastman Kodak
Co., Rochester, NY.
38. "Pilot Plant Testing for Municipal Sewage Treatment," R.
C. Moore, Elson T. Killam Associates, Inc., Millburn, NJ.
-------
A Color Removal Process
for a Neutral Sulfite
Semi-Chemical Pulp Waste James g Tay|or
Florida Institute of Technology
Melbourne, Florida
and
John Zoltek, Jr.
University of Florida
Gainesville, Florida
INTRODUCTION
In 1968 the United States passed theCiean Water Act. In 1972
this Act was amended to define effluent standards for all pulp
and paper plants using a neutral sulfite semi-chemical (NSSC)
pulping process. In the Federal Register under Pulp, Paper, and
Paperboard Point Source categories, Effluent guidelines and
standards, this law states in summary that all NSSC plants must
remove 75% of their effluent color by 1983.
This research was supported by the National Council of the
Paper Industry for Air and Stream Improvement for the
purpose of developing a color removal process for NSSC wastes
that would meet or exceed the 1983 effluent standards. The
technology required for effective and economic color removal
from NSSC waste had not yet been developed on a laboratory or
pilot plant scale.
History
In order to meet current EPA standards several different
physical and chemical processes have been proposed and
investigated for color removal from pulp and paper mill
effluents. Color reduction from kraft wastes by lime treatment
has been the most successful of all processes investigated.
However, lime treatment has not proven to be effective for col-
or reduction from other pulp mill effluents.
Herbert1' found that during lime treatment of a kraft, waste
reductions in organic carbon were linearly correlated to reduc-
tions in color. He also found that the settling characteristics of
the sludge improved as the lime dose was increased. Berger1 de-
veloped the massive lime process for color removal from kraft
wastes utilizing 5,000-25,000 mg/1 Ca(OH)2. The large lime
doses facilitated sludge handling and recovery.
Color reduction from a kraft waste was successfully imple-
mented by the Interstate Paper Corporation in Riceboro,
Georgia. Using a 1,000-1,500 mg/l lime dose they removed an
excess of 90% of the initial color of the kraft waste. Lime
recovery is not currently practiced by Interstate Paper at
Riceboro. Davis6 investigating the lime treatment process at
Riceboro, found the calcium concentration decreased as the
sodium concentration increased in the kraft waste. Davis
suggested that organic carbon, color, and calcium concentra-
tions after lime treatment were related to the sodium concentra-
tion in the waste.
Kabeya et al." demonstrated that activated carbon adsorbed
color from a kraft process waste at a very slow rate. Katoh and
Komura12 found that fly ash was nearly as effective as activated
; bon in adsorbing lignin from kraft mill effluents because of
' low absorption rate of activated carbon for color in a kraft
te. After extensive review of existing processes, Leszc-
»ki" concluded that only lime treatment was feasible for col-
or removal from a kraft waste.
Smith and Christman17 treated kraft and sulfite wastes with
aluminum and iron coagulants. Their research showed that
either coagulant would remove 90% of the initial color from the
kraft waste but that neither could be utilized effectively with the
sulfite waste. Alum reduced the color of the sulfite waste 67%
but produced a voluminous sludge that was difficult to handle.
Treatment of the sulfite waste by FeCI, removed over half of the
organic carbon but increased the original color of the sulfite
waste by some 200% to 300%. Phis illustrated that a reduction in
organic carbon is not always accompanied by a reduction in col-
or. Smith and Christman'7 proposed that the kraft waste had
sulfhydry 1 groups on lignin chains and that these groups formed
insoluble sulfides during coagulation. T he sulfonate groups on
the lignin chains in the sulfite waste were suggested to be acids
that formed hydrolysis products. This implied that color
removal from a kraft waste was the result of a chemical reaction
and that the color in the sulfite waste was removed by
adsorption on the alum floe.
Tejera and Davis21 used iron and aluminum salts as coagu-
lants in investigation of color removal from kraft caustic
extraction wastes and kraft chlorinated waste. Iron and alumi-
num chloride salts were capable of removing 96% of the color
from the caustic extract but, none of the coagulants were
effective for color removal from the chlorinated waste.
Separation studies on sulfite waste by Collins et al.5 and
Jensen et al.10 have shown large concentrations of high molecu-
lar weight of lignosulfonic acids. Collins et al.5 found that
lignosulfonic acids with molecular weights above 10,000 were
present in the sulfite waste liquor. Jensen et al.10 found six dif-
ferent components in sulfite waste liquors. Fractions above a
molecular weight of 40,000 were aromatic lignosulfonic acids
and were responsible for most of the color in the sulfite waste.
Spruill1* found, in full scale studies on a combined kraft-
NSSC waste, that lime treatment was ineffective for color
removal from NSSC waste. As the percentage of NSSC waste in
the combined waste increased the color removal due to lime
treatment decreased. The inability of lime treatment to effec-
tively refnove color from NSSC waste has been further docu-
mented by Domitar.7 A color reduction of only 40% from NSSC
effluents required a lime dose of 40,000 mg/1, far below the 96%
color reduction from a kraft waste at Riceboro, Georgia for a
lime dose of 1,000-1,500 mg/1.
Thompson23 using lime for pH control, was able to develop a
computer program that determined the optimum magnesium
dose as a function of color, turbidity, alkalinity and hardness.
Dubose* successfully extended magnesium coagulation to
wastewater treatment noting excellent phosphorous, turbidity,
and color removals.
-------
Color Removal Process 91
Rapson et al.1(1 successfully used seawater with lime to remove
color from a kraft waste. Seawater is an excellent source of
magnesium and is the main source of magnesium for the
manufacture of MgO. He noted that 10% and 20% seawater-
waste mixtures removed equal amounts of color. The floe
formed when seawater was present had a larger surface area
than the Hoc formed when lime only was used to remove color.
Rapson et al."' noted that color removal was not constant for the
different kraft effluents at the same seawater-waste mixtures.
The Canadian Pollution Abatement Research Program,
(CPAR),4 used lime and several different forms of magnesium
for color removal from a sulfite waste. They reported an 86%
color reduction from the NSSC waste using lime and MgClj,
and a 65% color reduction using MgCl2 without lime; thus were
able to consistently achieve an 86% color reduction from
bleached and unbleached kraft, combined biokraft, ammonia
base-NSSC and bio-NSSC waste effluents. Their work demon-
strated that magnesium had to be in a soluble form to be used for
color removal. They did not optimize coagulation pH or dose in
the coagulation process or correlate pH and dose to the initial
color of the wastes.
Procedures and Methods
Colored wastes were made by diluting spend sodium or
ammonium base neutral sulfite cook liquors to color levels of
2,500 and 5,000. MgS04 • 7H20 was the original form of the
magnesium used as the coagulant in the color reduction process.
Lime and NaOH were used for pH control of the coagulation
reaction. The lime was added in a slurried form, whereas the
NaOH was added from prepared 1 N and 10 N solutions.
Coagulation pH was also adjusted with H2S04 or HC1 solutions
when necessary. Polyacrylamide and amine based cationic,
anionic, and nonionic polymer stock solutions were prepared
from commercially available liquids and powders supplied by
American Cyanamid. The polymer solutions were stirred 24
hours before use.
Color was measured according to the procedures established
by NCASI15 in technical bulletin #253. All carbon measure-
ments were made on a Beckman Model 915 TOC analyzer. All
metal analyses was conducted by atomic absorption on a Varian
1200. Investigation of settleability was done by measuring
mobility with a Zeta Meter and determining the sludge volume
index as specified by Standard Methods|IJ. All other tests were
performed as recommended by Standard Methods
A three-step technique was used to determine the optimum
coagulation pH and dose for color removal. First, the coagula-
tion pH was found by determining the reaction pH where
maximum color occured for constant magnesium dose. Second,
the optimum coagulant dose was found for the previously
determined pH. Finally, this optimum pH was verified by
varying reaction pH for the optimum coagulant dose found in
the second step. All jars were rapid mixed at 100 rpm for three
minutes and slow mixed at 35 rpm for 15 minutes. The floe was
allowed to settle for 30 minutes before samples were taken for
analysis. Polymer additions and final pH adjustments were
made during the slow mix portion of the jar test.
Coagulant recovery was conducted by direct acidification of
dry sludge and by carbonation of incinerated sludge. Gas
mixtures for carbonation were controllec by separate rotome-
ters for C02 and air flow.
Results
The results of a three-step jar test are presented in Figures 1,2,
and 3 for color removal by magnesium coagulation. Lime and
NaOH were used separate for pH control and their effect on col-
or removal is evident in Figures 1 and 2. Because magnesium is
not amphoteric, no color return was experienced at higher pH.
8000
tt
I 6000
O
0
1
£ 4000
ha
o
¦5
o
2000
0
Figure I:
2000
<0
I l500
f
1000
w
o
o
o
500
0
Mg mg/l
Figure 2: Comparing NaOH and Ca{OH)2 for Color Removal
via Magnesium Coagulation
pH,
Figure 3: Magnesium Remaining in Solution as a Function of
Final pH
pH
Color Residual as a Function of Final pH
_¦ i i 1 i 1—
100 200 300 400 500 600
-------
92 Color Removal Process
I lie optimum pH and dose were defined as the minimum
coagulant dose and pH which produced a 90% color removal
from the NSSC waste. In Figure 1 an optimum pH of 10.6 was
selected. Both NaOH and lime function effectively for pH
control contributing to an excess of 90"/. color removal at pH
10.6.
I he data presented in Figure 2 shows that when lime is used
for pH control the magnesium coagulant dose is reduced by
approximately '/>. This has been suggested by Taylor et al.22 to
be the result of a reduced complex demand from the NSSC
waste on the magnesium due to the presence of CA++ from the
dissolution of lime. These tests were repeated for NSSC waste
with colors of 2,500 and 5,000, and the results demonstrated that
lime was better than NaOH for pH control. The coagulation pH
was verified and no shift in the optimum coagulation pH was ex-
perienced.
'The concentration of magnesium in the treated NSSC wastes
is presented as a function of pH in Figure 3, Approximately 40
nig I Mg++ remained in solution at pH 10.6. This represented a
significant loss of magnesium in the treated effluent. Since the
lime was relatively inexpensive it was decided to increase the
coagulation pH to II in order to recover more magnesium in the
Hoc. Also, if pH 11 was the desired coagulation pH, a slight shift
of the actual coagulation pH would have no adverse effect on
color removal. This is not so at pH 10.6.
The jar test results from the treatment of NSSC wastes with
different initial colors yielded two important observations. For
the color range investigated, the optimum coagulant pH did not
change as a f unction of color but the optimum magnesium dose
and lime requirements did. This suggested a stoichiometric
relationship between color and coagulant dose. In the case of the
effluent used in this study this relationship for 90% color
removal is given in equation 1 for lime and in equation 2 for
magnesium.
Magnesium as Mg mg/1 = (0.06) Initial Color (1)
Lime as Ca(OH)2 mg/1 = 750 + (0.10) Initial Color (2)
Taylor et al." described the mechanism of color removal from
this waste as a chemical reaction between magnesium, hydrox-
ide, and chromopores in the NSSC waste. Color removal by
rrmgnesm coagulation resulted in the formation of an organo-
metal precipitate having an imperical formula of Mg2OH3R,
where R represents a color producing molecule.
Seltleability
The purpose of the settling tests was to minimize the volume
of the sludge and gain some knowledge of the settling process.
The settling tests were conducted by measuring the sludge vol-
ume index, SV1, for the sludges produced during the color
removal process. Cationic, nonionic, and anionic polymers were
used as settling aids in these tests.
The type, functional group, charge and approximate molecu-
lar weight of the polymers used in the settling tests are presented
in Table I. This data can be summarized in the following
manner. The highly charged amine based cationic polymer was
found to have a negative effect on sludge settleability. The SV1
increased from 352 when no polymer was used to approximately
550 when as little as 0.10 mg/1 of the anionic polymer was ap-
plied. The polyacrylamide polymers substantially reduced the
SVI. Five mg/1 of the nonoionic polyacrylamide reduced the
SVI from 352 to 178. Thus a decrease in positive charge and an
increase in molecular weight was observed to reduce the SVI,
The slightly hydrolyzed, high molecular weight anionic polyac-
rylamide reduced the SVI to 81 at a dose of 3 mg/1. Highly
hydrolyzed, greater than 25%, high molecular weight anionic
polymers did not reduce the SVI anymore than did the slightly
hydrolyzed, approximately 5%, high molecular weight anionic
polymers. In general, the SVI was found to be reduced when a
slightly negatively charged high molecular polymer was used as
a settling aid. The decrease in sludge volume was significant,
enabling approximately a five fold increase in the volume of
sludge produced in the color removal process for a polymer dose
of 3 mg/1.
Hie dewatering characteristics of the color laden sludge were
not determined in these studies. Vaccum filtration tests per-
formed by Black et al.' at Melbourne, Florida on a magnesium
sludge yielded rates of I 1.7 to 20 lbs It- hr with a resulting
solids content of 45%. l.iptak (1974) found that compounds
precipitated by lime from wastewater can be vacuum filtered at a
rate of 2 to 6 lbs, ft2/ hr on a rotary vacuum f ilter with a resulting
solids content of 20%. NCASIIS determined that a magnesium
sludge with no polymer addition could be vacuum filtered at a
rate of 20 lb/ft2/day. After consideration of existing data a
vacuum filtration rate of 6 lbs ft-' hr and resulting solids
concentration of 20% was selected for a magnesium sludge that
had been previously thickened by polymer addition.
Table I: Polymer Description and SVI for Polymer Assisted
Sludges Produced from an Initial Color of 5,000, Ms++ = 35ft
mg/1, Ca(OH)2 = 1500 mg/1, pH = 10.8
Polyrrer Type
Polymer
[Dose mg/1
Subunit
Charge Molecular
Weight
575c Cationic
1905N Nonionic
1838A Anionic
837A Anionic
835A Anionic
Amine
Polyacrylamide
Polyacrylic Acid
Hydrolyzed Polyacrylamide 5S
Hydrolyzed Polyacrylamide 25%
High
Zero
High
Lew
High
500,000
15,000,000
15,000,000
15,000,000
15,000,000
Sludge Volume Index
None 575C 1838A 1905N 837A
835A
0.00
0.03
0.05
0.10
0.30
0.50
1.00
1.50
1.80
3.00
5.00
10.00
15.00
20.00
25.00
544
547
547
547
544
342
408
547
362
250
364
303
422
203
97
198
294
178
81
83
294
67
275
75
233
67
230
64
Recovery
Magnesium recovery from the color laden sludge was under-
taken for the purpose of reusing the magnesium in the color
removal process as the primary coagulant. To do this success-
fully, the color removed during coagulation could not be
allowed to return with the recovered magnesium. Studies by
Taflin2", on a potable water sludge involving magnesium
recovery by direct carbonation, had to be discontinued due to a
high color return with the recycled magnesium.
A color release experiment was conducted on a one liter
sample of NSSC waste with an initial color of 2,500. The waste
was treated with a magnesium dose of 150 mg/1 at pH 11 using
lime for pH control. The color of the waste after magnesium
coagulation was 200. When the pH of the treated waste was
lowered to 9 the sludge completely dissolved and the color of the
waste returned to 2,500. This process was repeated six times and
each time this pH change completely dissolved and reformed the
sludge. When the sludge was reformed the color returned to 200.
-------
Color Removal Process 93
When the sludge was dissolved the color returned to 2,500.
If the NSSC waste possessed high carbonate alkalinity and
significant calcium hardness there was the possibility that the
color bodies would remain with the precipitated CaC03 during
sludge carbonation. This was very unlikely considering the work
of SpruillIK and others who reported that lime treatment of
NSSC waste for color removal was ineffective. Nevertheless, an
experiment was conducted using CaCO, precipitation for NSSC
color removal. The results of this experiment confirmed that
CaCO, was ineffective for NSSC color removal. An NSSC
waste with an initial color of 5,000 was treated by forming
varying concentrations of CaCO, solids in situ and measuring
the resulting color. The maximum solids concentrated precipi-
tated from one liter of NSSC waste was 25,000 mg/1. The
resulting color removal was 70% of the initial color. There was
no color removal when less than 1,000 mg/1 of CaC03 solids
were precipitated from solution, which is a reasonably upper
limit on the concentration of CaCO, that might be precipitated
from treating NSSC waste for color removal. On the basis of this
and the work of Spruills"* it was concluded that the color would
have to be removed from the magnesium floe before recovery.
Incineration was selected as an intermediate recovery process
before magnesium recovery because the color was organic and
could be converted to a gaseous form at high tempgrature.
Magnesium sludge was prepared by treating 40 liters of NSSC
waste for color removal with magnesium using lime for pH
control. A mass balance on magnesium revealed that 96% of the
available magnesium was recovered in the precipated solids. All
of the magnesium dosed as a coagulant was recovered in the
solids. The extent of magnesium recovery will depend on the ini-
tial magnesium concentration in the waste. Because of the
solubility of the color laden magnesium sludge there will always
be approximately 10 mg/1 Mg++ in the treated waste at pH 11. If
the initial magnesium concentration is greater than 10 mg/1 the
total magnesium recovered could exceed 100%.
In order to determine the optimum incineration temperature
the sludge was first dried at 103°C. Approximately one gram
samples were subjected to incineration temperatures beginning
at I50°C and progressing to 850°C in 100°C increments. The
solids remaining after incineration were dissolved by acidifica-
tion with HC1, diluted and the resulting solution was measured
for color and magnesium concentrations. From this data a
magnesium to color ratio was calculated to determine how much
color returned per mg of magnesium recovered in the carbo-
nated solution. The results of this experiment are presented in
Figure 4. The color to magnesium ratio was constant at
temperatures higher than 550°C. As a result of this experiment
550°C was selected as the temperature of incineration.
The magnesium could be recovered from the sludge by
acidification with a strong acid or by carbonation with C02gas.
Since flue gas is abundant at pump and paper mills, carbonation
was selected for magnesium recovery. A 10% CO2-90% air
gaseous mixture was used to carbonate the incinerated solids.
The incinerated solids were carbonated for 120 minutes. The
data from the recovery experiments is shown in Figure 5. All of
the magnesium in the incinerated solids was recovered when a
concentration of 5318 mg/liter of incinerated solids was
carbonated for 45 minutes. When higher concentrations of
nonvolatile solids were carbonated the magnesium concentra-
tion increased in the supernatant but the degree of magnesium
recovery decreased. The maximum magnesium concentration in
the carbonated liquor was not determined. An equilibrium
condition limiting magnesium solubility was never reached.
However, these experiments did demonstrate that all of the
magnesium in the incinerated solids could be recovered by
carbonation with a gaseous mixture similar to flue gas. After
carbonation some solids similar in appearance to granular
activated carbon were still in the solution.
24
20
0
£
v.
M
1 i6
o
0
1
£
o 12
o
ac
2E
4
°<
Incineration Temperature °C
Figure 4: Color/Mg++ Ratio as a Function of Incineration
Temperature
Magnesium Reuse
Incineration and carbonation processes were used to recover
the magnesium used in the color removal process. Each of these
processes affected the chemical form of the magnesium. A
magnesium reuse experiment was performed in order to
determine if the recovered magnesium could be successfully
reused in the coagulation process.
The magnesium was recycled twice. Following each use, the
magnesium was recovered by incineration at 550°C for 15
minutes and then carbonated with a 10% C02 gas. The
nonvolatile solids concentration was 5318 mg/1 during carbona-
tion. Some of the nonvolatile solids were not dissolved during
carbonation. These remaining solids were recycled with each
magnesium reuse. The magnesium dose was based on the
soluble magnesium in the carbonated liquor and the coagulant
dose relationship given in Equation 1. The data from these
magnesium reuse experiments are summarized in Table 11.
Table II: Color Removal by Lime-Magnesium Coagulation
Using the Same Magnesium Three Times. Magnesium Recov-
ery was accomplished by incineration and carbonation follow-
ing coagulation. Nonvolatile solids not dissolved by carbona-
tion were recycled with the recovered magnesium.
Jse of
Magnesium
Per oant of
Original Magnesium
In Soluble Form
Per oent of
Oolor Removed
First
100
92
Second
66
92
Huxd
92
91
\
\
K
\
aT
o 15 mln.
• 30min.
° 60min.
a T • Incineration
time
50 250 350 450 550 650 750 850
-------
94 Color Removal Process
Alter incineration the sludge remaining after the first use of
the magnesium contained 99.6% of the initial magnesium.
However, only 66% of the magnesium was in a soluble form
alter the sludge from the first use was carbonated. The color of
this solution was 600. The remaining magnesium was still in the
nonvolatile solids that were not dissolved during carbonation.
When the .sludge from the second magnesium use was
carbonated, 92% of the magnesium was in a soluble form. The
color of the recovered liquor was 80. The difference between the
percent of magnesium solubilized after the first and second
carbonation processes was probably due to the incomplete
combustion of the color bodies after the first magnesium use.
The incinerated sludge contained 77% nonvolatile solids after
the first magnesium use. The average novolatile solids reduction
in the previous experiments for 550°C was 45%.
Practically all (99.6%) of the magnesium had been recovered
after it had been used in the color removal process. Greater than
90''? of the initial color was removed with each of the three
magnesium uses. The magnesium dose was the same for each
use. The recovered magnesium and the undissolved solids
removed as much color in the second and third uses as did the
fresh magnesium in the first use. It was concluded that the
magnesium could be successfully recovered and recycled in the
lime-magnesium color removal process after the incineration
and recovery processes.
A second set of magnesium reuse experiments was conducted
to determine the effectiveness of the recycled solids that were not
dissolved in the carbonation process. The recovered magnesium
solution was filtered through a 0.80 micron Millipore filter to
remove the solids. The reused magnesium that contained no sus-
pended solids removed 13% less color than did an equivalent
amount of an unused magnesium when both were used sepa-
rately in the color removal process. The presence of the
incinerated solids was a significant aid to the reused magnesium
in the color removal process. These solids probably provided
nucleating surfaces for the forming solids phase.
Application
The color removal process consists of several different unit
operations. Design and cost data were estimated for the color
removal process based on the laboratory experiments for
14,000 V
=1,12,000
E
110,000
I
«»
8000 Y
§ 6000
I
1 4000
2000
NVS-mg/l
• 5318
• 22,950
• 33,561
0 74,550
*¦ 119,692
Mg mg/l
1300
5000
7317
16,252
26,095 A
50 75
Carbonation time minute#
100
Figure 5: Magnesium Recovered as a Function of Carbonation
me
coagulation, sedimentation, incineration, and carbonation.
Vacuum filtration design and cost data were estimated from
l.iptak14. The design parameters were developed for an NSSC
waste with a color of 5,000 and a flow of I mg/d.
A velocity gradient of 1,000 sec was recommended by the
AWWA (1969) to achieve adequate coagulant dispersion during
rapid mix in a contact time of 20 seconds. This could be
provided by 1.5 horsepower in a tank volume of 30 ft'. The lime
and magnesium doses were determined from equations 1 and 2
to be 10,425 lbs/ mgd lime and the magnesium requirement was
2502 lbs;'mgd.
The area required lor settling was determined to be 1200 ft2. A
3 mg, 1 dose of hydroly/.ed anionic polymer was used as a settling
aid. The overflow rate from the sedimentation basin would be
1034 gpd/ft-. The solids in the settled sludge would include the
magnesium precipitate and a CaCOj precipitate which would
come from the reaction of the carbonated recovery liquor and
lime. The percent solids in the settled sludge would be approxi-
mately 2%. Based on a design rate of 6 lbs/ ft2/hr the vacuum
filter treating the color laden sludge would require an area of 202
ft-1. The resulting sludge was estimated to have a solids content of
20%, l.iptak14.
The energy requirement of the incineration process was
estimated by reducing the minimum energy value of lignin
sludge by the ratio of the volatile solids in lignin sludge to the
volatile solids in the magnesium sludge, then considering the
amount of water to be vaporized in the sludge. The energy value
of ligning sludge is 8,000-10,000 BIT)/lb and it contains 70%
volatile solids. The energy value of the magnesium sludge was
estimated to be 5,142 BTU/lb. A total heat requirement
exceeded the avilable heat by 7,700,000 BTU.
The flow of the 10% COr90% air gaseous mixture was 2,122
CCi min. For a flue gas of similar C02 composition a flow of
9,167 cfm would be required to treat the solids produced from
the treatment of a NSSC waste with a color of 5,000. The
magnesium concentration in the recovery liquor was 1,300 mg/1
and a recirculation ratio of 0.23 would be required to maintain
the coagulant dose given in Equation 1.
A complete flow chart for the color removal process is
presented in Figure 6. T he additional operations of vacuum
filtering the carbonated sludge and lime recovery are shown.
These are optional but will lower the unit cost for incoming
NSSC wastes with a flow greater than I mgd.
A cost estimate was made for treating an NSSC waste by the
magnesium-lime color removal process. These costs are based
on an estimate of $200/ton of NSSC product produced. An
increase of 3.7% to 2.7% would occur in the manufacturing cost
of NSSC product if the proposed color removal process was
implemented to treat an NSSC waste flowing from 5 to 10 mgd
with an initial color of 2,500. If the initial color was 5,000 the
increases would range from 4.5% to 3.3%) for the higher and
lower flows. The unit cost was found to decrease with decreasing
initial color and increasing flow. However, the annualized
equivalent expenditure would be minimized by not diluting the
highly colored waste sources from the NSSC process and
treating these separately.
SUMMARY
A process for removing 90% of the initial color in an NSSC
waste has been implemented on a laboratory scale using a
magnesium-lime treatment process. A stoichiometric relation-
ship was developed for the magnesium and lime requirements
for 90% color removal from the NSSC waste. After color
removal a 5% hydrolyzed anionic polymer was found to reduce
the sludge volume by approximately five fold.
It was necessary to remove the color from the sludge before
recovery. This was done by incineration at 550°C. The inciner-
ated magnesium was recovered from the solid form by carbona-
-------
Color Removal Process 95
Figure 6: Flow Diagram for Lime-Magnesium Color Removal Process
tion. By utilizing recovery by carbonation the same magnesium
was used in three separate instances to remove over 90% of the
initial color from an untreated NSSC waste. After the third use
93% of the original magnesium was available for recycle.
A simple chemical representation of the process might be as
follows:
In these chemical equations an assumption is made that
MgCO, • 3H20 is the controlling solid phase as pointed out by
Black et al.' for magnesium-lime treatment for potable water. It
should be pointed out that this research has not determined if
this hypothesis will apply when recarbonating incinerated solids
from the treatment of NSSC waste by magnesium and lime.
Color Removal
2Mg++ + 2CA++ + 40H + R-H = Mg2(OH)3R I + H20 + 203^
(3)
Incineration
Heat
REFERENCES
Mg2(OH)3R = 2HgO + H2O + miscellaneous gases
Recovery
C02 + 3H20 + MgO =
MgC03 • 3H20(s) = Mg2+ + C032~+3H20
Recycle
2Mg++ + 2HCO3 + R-H + 2Ca = 20H~ =
Mg2(OH)3R I + 2CaC03 I + H20 + H+
1. Berger, H. F. U.S. Pat. 3,120,464 (Feb. 1974).
2. Black, A. P. "Full Scale Studies of the Magnesium
Carbonate Water Treatment Process at Montgomery,
Alabama and Melbourne, Florida." EPA Project #12120
HMZ (Sept. 1974).
3. Black, A. P.; Thompson, C. G.; Singley, J. E. "Magnesium
(4) Carbonate—A Recycled Coagulant." JAWWA, 64\ 1: 11
(1972).
4. Canadian Pollution Abatement Research Program. "Color
Removal from Biologically Treated Pulp and Paper Mill
Effluents." CPAR Project Report 21 D-l (1974).
5. Collins, J. W.; Webb, A. A.; Didwania, H. P.; Lueck, B. F.
"Components of Wood Pulp Effluents." Env. Sci. & Tech.,
(5) J: 371 (1969).
6. Davis, C. "The Effect of Sodium Ion Concentration on the
Removal of Color from Kraft Linerboard Mill Effluents."
Paper presented at the 20th anniversary meeting of Sou-
theastern Tappi, Jacksonville, Florida (1972).
7. Dimitar Limited Research Center. "Colour Removal from
Biologically Treated Pulp and Paper Mill Effluents."
(6) CPAR Project Report 210-1 (Mar. 1974).
-------
96 Color Removal Process
8. Dubose, A. "The Effect of Magnesium Concentration on
Municipal Wastes." Ph.D. Dissertation, University of
Florida (1973).
9. Herbet, A. J. "A Process for the Removal of Color from
Bleached Kraft Effluents through Modification of the
Chem-Recovery System." NCAS1, Technical Bulletin No.
157 (June 1962).
10. Jensen, W.; Fremer, K. E.; Forss, K. "The Separation of
Components Spent Sulfite Liquor." Tappi, 45: 122(1964).
11. Kabeya, H.; Fujii, T.; Kubo, T.; Kimura, Y.; Urano, K.
"Renovation of Pulp Mill Waste Water Adsorption Char-
acteristics of Kraft Pulp Lignin on Activated Carbon."
Kanipa Gikvoshi (Jap.),26: 3: 125. Chem. Abs.,71: 2454It
(1972).
12. Kotoh, S.; Kimura, Y. "Study of Renovation of PulpMill
Waste Water by Treatment with Fly Ash." Jour. Jap.
Tappi, 25; 4: 168 (1972). Abs. Bull. Inst. Paper Chem., 42:
8176(1972).
13. Leszczynski, C. "Decolorization of Kraft Mill Effluents."
Prezegl. Papier (Pol.), 28: 3: 88 (1972). Abs. Bull. Inst.
Paper Chem. 43: 4154(1972).
14. I.iptak, B. G. Environmental Engineer's Handbook, Vol. 1,
Chilton, Radnor, PA (1974).
15. NCASI Technical Bulletin #253, "An Investigation of
Improved Procedures for Measurement of Mill Effluent
and Receiving Water Color." (Dec. 1974).
16. Rapson, B.;Sullivan, D.P.;Brothers,J.S."TheNRSFSea
Water-Lime Clarification Process for K raft M ill Effluents "
Presented at the 60th Annual Meeting of Technical Section
C.P.P.A., Montreal, Canada (1971).
17. Smith, S. E., Christman, R. F. "Coagulation of Pulping
W astes for the R emoval of Color." JWPCF, 41 ¦ 2- 222 (Feb
1969). ' V
18. Spruill, E. L. "Color Removal and Sludge Recoverv from
Total Mill Effluent." Tappi, 56: 98(1973).
19. Standard Methods for the Examination of Water and
Wastewater, APNA-AWW A-WPCF, 13th Edition, Wash-
ington, D.C., 1971.
20. Taflin, C. O.; Weber, N. F.; Kramer, A. S.; Whitaker, J
"Minneapolis Keeps on Trucking." Water & Wastes Ene
Reprint (May 1975).
21. Tajera, N. E.; Davies, M. W„ Jr. "Removal of Color and
Organic Matter from Kraft Mill Caustic Extraction Waste
by Coagulation." Tappi, 53: 10(Oct. 1970).
22. Taylor; J.S., Zoltek, J.; Singley, J. E. "Color Removal bv
Magnesium Coagulation." 96th Annual Conference Pro-
ceedings, AWWA, New Orleans, Louisiana (June 1976)
23. Thompson, C. G.; Black, P. P.; Singley, J. E.;"Magnesium
Carbonate a Recycled Coagulant for Water Treatment"
Water Pollution Control Research Series 12l9n
ESW06/7I. '
-------
Polyester Encapsulation of
Hazardous
Industrial Wastes
R. V. Subramanian, Wen-Pao Wu
Department of Materials Science &
Engineering
R. Mahalingam, M. Juloori
Department of Chemical Engineering
College of Engineering
Washington State University
Pullman, Washington
INTRODUCTION
This paper introduces a new and effective process to the
technology of treating toxic industrial wastes by chemical
fixation. It involves the dispersion, encapsulation and immobili-
zation of hazardous residuals in a polyester matrix.
The dominant feature of current industrial development is an
increasing concern to prevent pollution of the environment by
hazardous industrial wastes. Stringent regulations on air and
water contamination have resulted in the need to develop
pollution control technology based mainly on land disposal of
pollutants. The basic requirement of such processes is the
conversion of hazardous residuals in the form of liquids or semi-
solid sludges to solids for safe handling, transportation and
storage with minimum potential for contamination of the envi-
ronment. Residuals management by this method would be
acceptable only if the end product does not release unacceptable
levels of pollutants to the soil, air and water by the action of
biological, physical or chemical processes.
Chemical fixation and solidification is the primary approach
recently taken to convert industrial waste water to a form
suitable for land burial4'*-12. Chemical stabilization is achieved
by the addition of chemicals to hazardous residuals or the
mixing of waste streams to form solids which encapsulate or
bind the pollutants and thus immobilize them. The processes
that fall into this category can be broadly classified as inorganic
and organic processes4 based mainly on the types of reactants
used and the nature of the reactions that occur in the process.
The scope of inorganic processes, which for sometime depended
mainly on the use of Portland cement and lime based mortars,
have now been expanded by the development of the patented
Chemfix process, which utilizes soluble silicates and silicate
setting agents which react with (toxic) polyvalent metal ions to
produce a pseudo-mineral solid matrix.4 Generally cements and
mortars produce porous structures which allow water
permeation and leaching out of water-soluble components. The
most commonly used organic reagents in chemical fixation have
been asphalt, tar, polyolefins, epoxy resins and urea-
formaldehyde mixtures.
The organic reagents are generally hydrophobic. As such,
they are best suited to deal with organic wastes and are not
usually compatible with aqueous systems. Thus, they comple-
ment the application of inorganic reagents which are compatible
with water-based hazardous residuals. The urea-formaldehyde
system, however, has been used extensively in aqueous solu-
tions, mainly with low level radioactive wastes.
Both organic and inorganic processes share a common
problem of chemical fixation, viz., sensitivity to reaction
conditions and specificity to particular waste components. The
urea-formaldehyde reaction, for example, requires acid
conditions for initiation; waste solutions at high pH values will,
therefore, not be solidified by this reagent. Finally, difficulties
may be encountered in solidification of sulfate wastes in urea-
formaldehyde or of boric acid concentrates in Portland cement.3
Industrial wastes, however, are complex mixtures, and place a
heavy demand on the versatility of chemical fixation systems for
their efficient utilization and wide application.
It is in this context that a well-developed technology from
polymer science has been applied in our laboratories as a novel
concept of immobilizing hazardous residuals by chemical
fixation.12 In this method, unsaturated liquid polyester resins
are used which have been formulated specifically to produce
stable, water-in-polyester emulsions by dispersion of water into
the resin at high shear. The continuous resin phase in the
emulsion is cured by the addition of peroxide catalysts to pro-
duce a hard, water-containing solid resembling fine grained
plaster. The combination of organic and aqueous phases in a
simple experimental procedure to produce a solid monolith
after a chemical reaction contains the essential ingredients of a
useful chemical fixation process. The individual encapsulation
of dispersed aqueous droplets by thin polyester shells agglomer-
ated into a superstructure has also the potential advantage of
truly immobilizing the waste contained in-the aqueous phase
with negligible leachability.
This concept was first applied to the immobilization of model
low level radioactive wastes as described in an earlier pub-
lication from our laboratories.12 In this paper it was shown that
simulated (radiation-free) wastes typical of those resulting from
nuclear power generating stations can be dispersed in water-
extensible polyesters to form stable emulsions that subsequently
can be set, by the addition of peroxide catalysts, to form
lightweight (50 to 70 lb/ft1), homogeneous, coherent, rigid,
shockproof structures. In this study, sodium sulfate and boric
acid solutions (typical of evaporator bottoms), and ion
exchange resin beads and powder were used as model low-level
rad wastes.
The study has now been extended to investigate the applica-
bility of our novel process to the immobilization of a number of
hazardous residuals16 and the first results are presented in this
paper. In view of the desirability of a widely applicable and
versatile system, hazardous wastes having a wide spectrum of
chemical compositions have been studied. The experimental
wastes were obtained from industry as representative of pollu-
tants that are difficult to handle or untreatable by existing
technology. In some instances, the wastes were prepared
according to the composition of the waste streams supplied by
the producer or disposal company. Toxic metal solutions,
97
-------
98 Polyester Encapsulation
cyanide wastes, arsenic compounds, Kepone and polychlorobi-
phenyls (PCB) are thus represented in this investigation. The
teachability of encapsulated wastes has been determined, and
illustrative results of dynamic and static leaching experiments
are presented here. The process has been extended to the pilot
plant stage7 and the results of the study are presented in a
companion paper at this conference.10.
Experimental
Materials
Most experiments were done with the water extensible
polyester Aropol WEP-661 P obtained from Ashland Chemical
Company. Similarly, initiator peroxides were also obtained
from commercial suppliers, Lupersol Delta from Pennwalt,
Superox 38 from Reichhold Chemical Inc. and Aposet from M
& T Chemicals.
Waste materials were either synthesized in the laboratory or
obtained directly from industries that produce or treat chemical
Wastes. Table 1 lists the type of wastes, toxic components and
method of preparation.
Table I: Hazardous Industrial Waste Types—Sources and
Composition
Table 1 (cont.)
A. '.imulJtcrt Radioactive Wastes
A 1 Su'11 urn su) t ate
solution
\/ Uonc acid
solution, pH b-lU
AJ iioric acid
solution, pH b-IU
Laboratory
Laboratory
M YR sodium
sulfate
AM VW sodium
borate
A<1 VH sodium
bora to
AJS
a. Radioactive Wastes
ill sodium sulfate I aboratory
so)u 11on
20 ooric dci (1
Ic. Chemical Wastes
|ci Heavy metals and
mixed organic
waste
|c2 Organic chloride
waste
3 Organic waste
Laboratory
CFP
CFP
Compos i ti on
24'fi sodium sulfate anhydride
76% dionized water
12% boric acid solution
neutralized with NaOH to
desired pH
201 boric acid solution
neutralized with KaOH to
desired pH
Powder dehydrated from so-
lution containing 20%
Na^SQ, , 0.2% undissolved
solid, 0,2% (NH ), HPO, ,
0.4*; MgCO, and 0.4% CaCO,.
Powder dehydrated from so-
lution containing 10*
H ,80,, 0.2% undissolved solid
and 0.5% LiON neutralized
with NaOH.
Same as A8, with extra
Na2S0(f, antifoaming agent,
motor oil, etc., to simulate
real radioactive waste.
24% sodium sulfate with 0.1
v,Ci/ml each of Co 1 , Cs
and SrflS.
20% boric acid solution
neutralized to pH 8 with
NaOH; 0.1 uCI/ml each of
rn^o rslv*. and Sr8^ added.
Simulated waste from metal
finishinq industry^ con-
taining St>, Cr , and
organic compounds
Organic chloride waste
from pharmaceutical plant.
NaoS0.4, NH and other
organic compounds.
Synthetic mixture of haz-
ardous organic materials,
phenols etc.
Waste type
Source
Composit i on
C4 Pigment sludge
CFP
Pigment sludge from pigment
manufacturing industry
Ch Mercury
Laboratory
\ i and Si mercurit
chloride solution
Cb Chloride reagent
waste
laboratory
Waste containing 0.0625;,
Hg(SCN) IS; methanol, J.U3t
FeINO ) ( .9H 0 and U.9H% HNO
C? Process slurry
CPS
Waste containing 201 metal
oxide solids, 4U% solvent as
alcohols, ketones, and oxy-
genated solvent, and 40%
water.
CB Cyanide solution
CCK
Actual waste containing
U.{U2* CN and other heavy
metals as Cu, Ni, 7n.
C9 Cyanide sludge
CCK
Cyanide solution treated wit>
Ca(OH) and ferrous Sulfate
pickle 1iquor.
CIO Kepone sludge
ACM
Sludge containing kepone and
arsem c.
c.n pen
WWP
Polychlorobiphenyls from
capaci tors
C12 Arsenic
Laboratory
Arsenic Trioxide powder
C13 Arsenic
Laboritory
Powder contains 49%
NaCl, 49% Na,S0H and
2% Cacodylic' acid.
C14 Arsenic
solution
Laboratory
1% sodium arsenate,
Ka?HAs0lt • 7H?0
A. Three letter codes indicate wastes supplied by coded industrial
sources.
Dispersion and Solidification
The experimental procedures for dispersion and solidification
were simple and varied according to types of waste, as follows:
(i) Liquid wastes were dispersed in the water-extensible polyes-
ter resin in a Waring Blender to form an emulsion containing the
aqueous waste droplets encapsulated by a thin skin of the resin
matrix. The dispersion was achieved by slow addition of the
waste to the resin vortex with the blender running at high speed
(above 1500 rpm).
(ii) Slurries were also dispersed in the same way as liquid wastes
to form the emulsion and disperse the solid particles uniformly
in the emulsion.
(iii) Solid wastes were either dispersed in a preformed emulsion
(water-in-oil) or directly mixed with neat polyester resin. In
general, directly mixing with polyester produced a faster
solidification reaction, eliminating or minimizing waste-
initiator interactions.
After the emulsion (or solid-resin mixture) was formed, a
measured amount of initiator was stirred into the emulsion/or
mixture and solidification conducted in a plastic vial, 5 cm high
and having 3.2 cm I.D. A thermocouple wrapped with alumi-
num foil was inserted into the emulsion to measure the peak
exotherm and the time to peak exotherm.
Leachability
Leachability tests were conducted to determine the amount of
waste leached out of the solidified matrix when held immersed in
water. Cylindrical specimens 3 cm * 3.5 cm were cast in plastic
vials for these tests. Both static and dynamic leaching tests have
been performed with the encapsulated wastes. In non-
radioactive wastes, elements which are suitable for atomic
absorption or other analytical methods were chosen as indicator
-------
Polyester Encapsulation 99
elements, teachability, L.n, was calculated from the formula
Ln= W"
Wf
F
V
CnV£
Wo
F
V
where Wn = total amount of tracer leached out after a per-
iod of 'n' days (g)
W0 = initial amount of tracer present in specimen (g)
F = exposed surface area of specimen (cm2)
V = volume of specimen (cm )
Cn = concentration of tracer in leachant (g/C)
V = volume of leachant (1)
Based on leachability, the leaching rate, Rn, can also be cal-
culated as a function of time:
Rn =
Wn/Wp
(F/V) tn
where tn is elapsed time (day)
Based on leachability, the leaching rate, Rn, can also be
calculated as a function of time:
[-O-CO-CH= =CH-C0—0-R] n-0-
where t„ is elapsed time (day).
In static leaching, cylinders of solidified waste were totally
immersed in 200 ml deionized water contained in 250 ml, wide
mouthed plastic bottles, one cylinder in each bottle. Periodi-
cally, 2 ml aliquots were withdrawn from the bottle for analysis
of tracer element leached out from the encapsulated waste.
For specimens with higher leachability, a procedure based on
that described by Hespe6 was applied. Periodically, the speci-
men was removed from the leachant and placed in 200 ml of
fresh leachant contained in another bottle.
An improved dynamic procedure for determination of leac-
hability was also developed using continuous recirculation of
leachant through a chamber containing the specimen. The flow
rate of leachant was regulated to be in the range of 0.3-3 meter
per day to simulate ground water flow. The total amount of
leachant was five liters. The large amount of leachant also
provided for minimal change in concentration gradient during
the experiment.
In the case of radioactive wastes, the activities of specimens
were counted prior to leaching. The specimens were retrieved
from the leachant and placed on the counter in identical
positions for counting. Radioactivities were compared with a
control specimen and percent retention calculated.
Mechanical Properties and Resistance to Gamma Radia-
tion
Compressive strength of the solidified products was tested on
an Instron Testing Machine. A cross-head speed of l.Omm/min
was used. Specifications of ASTM D 695-69 were followed in
preparing specimens. Specimens were cast in tubes of 1.27 cm.
inside diameter and were cut to a length of 2.54 cm. At least five
specimens were used for each sample to obtain an average value.
Specimens were also exposed to a Co60 gamma radiation
source to see the effect of gamma radiation on the compressive
strength of the solidified products. Specimens were irradiated
for different lengths of time to reach a dose in the range from 4 *
106 rad to 5 * 10s rad.
Scanning Electron Microscopy
Scanning Electron Microscopy (SEM) was used to study the
surface and interior detail of the encapsulated product. The
structure of the closed cell before and after leaching can be ex-
amined thus. Figure 1 shows the closed cells at a fracture surface
exposed when a specimen was broken. The diameter of the
encapsulated droplets is in the expected range of 1-10 microns.
Results and Discussion
In discussing the results of the evaluation of the polyester
process with different kinds of wastes, the important aspects to
be taken into consideration are the ease of dispersion of the
wastes in the resin, the stability of the emulsions thus formed,
the curing reaction leading to solidification of the emulsion, and
the properties of the resulting product. In essence, it is the
physical and chemical compatibility of the hazardous residual
with the polyester-emulsion-catalyst system that is being stu-
died. The mechanical integrity of the solidified products under
relevant environmental conditions and the actual immobiliza-
tion of the toxic components in the polymer matrix as measured
by leachability tests have also been determined. The basic
features of the chemistry and structure of water-extended
polyester systems which are relevant to the current application
will be reviewed before discussing the detailed results.
Water-Extended Polyester
Linear polyesters are prepared by condensation of glycols
with dibasic acids; the water-extendible polyesters (WEP) used
here are unsaturated polyesters which contain carbon-carbon
double bonds in the backbone of the polymer chain. The
unsaturation results from the use of fumaric or maleic acids in
the synthesis of the polyester, so that the polymer chain carries
segments which can be represented as follows:
0—-CO—-C H==CH—-CO—0—R
—0—
n
The amount of unsaturation is thus controlled by the proportion
of maleic or furmaric acids used with other dibasic acids. The
chemical composition, physical properties and water miscibility
of the polyester can thus be controlled by a suitable choice of the
type and proportion of different dibasic acids and glycols. Thus,
water-extendible polyesters are specially formulated to allow
the preparation of water-in-oil emulsions.2 The unsaturated
polyester is dissolved in polymerizable monomer, usually
styrene,C(,H5CH=CM2, to form low viscosity liquids into which
water can be dispersed as 2-5 m droplets.
The gelling and .curing of the resin phase to form a hard
polymer which encapsulates the water droplets is achieved by
initiating the polymerization of the styrene monomer by a
suitable catalyst system producing free radicals. The free
radicals open up the double bonds of the monomer and the
unsaturated polyester and crosslink them into a network
structure in which the polyester chains are joined together by
polystyrene chains as shown here.
/C6»5
—0—R—0—-CO—CH—CH—CO—0—R—
( CH—CHy\
yu %
-0—R—0—CO—HC— CH—CO—0—R—0—
£
-4—CH— c^
k
V I 7
A
-------
100 Polyester Encapsulation
Figure 1: Scanning Electron Micrograph Showing Closed Cell
Structure of Water-Extended-Polyester Composite
The catalyst system for initiating polymerization under mild
room temperature conditions consists of a 'promoter', and an
initiating peroxide which produce the required free radicals by
mutual interaction. The promoter, about 0.5%, is usually
already present in the polyester, in which case the polyester is
said to be 'promoted', and is a reducing agent such as cobalt
naphthenate, cobalt octoate or dimethylaniline. A variety of
peroxides, water soluble or insoluble, can be used as the initiator
peroxide which is added after emulsification to cure the resin
phase. Methyl ethyl ketone peroxide and hydrogen peroxide are
most commonly used for this purpose.
Closed-Celt Structure of Cured Solids
The curing of the continuous resin phase of the emulsion
consists of crosslinking of the liquid polyester by the polymeri-
zation of styrene in the mixture to give a solid crosslinked
structure. The encapsulated water droplets in the polyester thus
represent a closed-cell structure as shown in Figure 1. The
separation and encapsulation of individual droplets by the resin
shell is clearly seen in this picture, a scanning electron micro-
graph, of the fracture surface exposed by breaking a cured
specimen of water-extended polyester. Since the maximum vol-
ume fraction of closed-packed spheres is 74%, this would be the
limit of incorporation of any aqueous solution in the matrix
though higher volume fractions may be achieved by a distribu-
tion of sizes of the spheres and by distortion of particle shapes.
The significance of the closed cell structure to waste immobiliza-
tion is seen in the fact that the leachability of the encapsulated
toxic components in the aqueous phase is thus significantly
reduced by the protective polymer shell, as later results will
confirm. It is therefore important to recognize that some types
of commercial water-extendible polyesters, which have been de-
veloped to produce an open-cell structure on curing,15 would be
unsuitable for waste solidification.
It is interesting to point out that many otherchemical fixation
processes, such as urea-formaldehyde or the Chemfix process
also utilize the production of a crosslinked matrix to solidify the
wastes. In the Chemfix process, a three dimensional crosslinked
network is formed between polyvalent metal ions and silicate
chains, resulting in a rigid inorganic polymer matrix resembling
natural pyroxene minerals. However, a two phase system is not
involved, the structure is essentially porous, and the linking of
toxic metal ions to the matrix is by ionic bonding. The urea-
formaldehyde system produces a fairly open organic matrix
structure in which aqueous wastes are occluded in interconnect-
ing pores which seem to be readily accessible to leachants.
Curing Parameters and Low-Level Radwastes
As reported earlier,12 the dispersion and solidification of
aqueous sodium sulfate and boric acid solutions as model low-
level radwaste materials has been readily achieved in the
polyester process. Thus, up to 75 wt.% of a 24% sodium sulfate
solution can be incorporated in the polyester matrix. Similarly,
more than 70 wt.% of 12% boric acid at room temperature or
20% boric acid at 50°C, both at pH 8, can be incorporated.
Further experiments with these simulated wastes have provided
significant information regarding curing conditions and process
parameters for the polyester process. The compositions of
wastes are given in Table I and the results of encapsulation
experiments are summarized in Table II.
2 3 4
INITIATOR CONCENTRATION ,%
Figure 2: Dependence of Curing Rate on Concentration of
Different Initiator Peroxides.
The polymerization reaction leading to curing is an exother-
mic reaction. The encapsulated aqueous phase serves as an
efficient heat sink and moderates the curing reaction, but the rise
in temperature due to the heat evolved can be determined by a
thermocouple embedded in the solidifying emulsion, and used
as a measure of the rate of curing. In fact, it is found that the
-------
Polyester Encapsulation 101
160
140
120
X 100
UJ
X
h
O
X
UJ 80
<
UJ
0.
o 60
40
20
RESIN: AROPOL WEP 661-P
Q
WASTE". 24% N(^S04
temperature; 25°C
\ o
75% WASTE
. \
\ o
70 % WASTE
D
60 % WASTE
\
M. A
50 % WASTE
- \ \
\ o
- V
~
A
1
I
' '
initiator Concentration, % 5
Figure 3: Variation of Curing Rate with Concentration of
Initiator (Lupersol Delta) for Emulsions of Different Waste
Content.
.060
time-to-peak exotherm shows regular variations with the curing
conditions; such variations shown in Figure 2, for example, as a
function of initiator concentration, indicate that an optimum
initiator concentration is reached at 1% based on weight of the
resin in the emulsion formed from an aqueous, 2 sodium sulfate
solution. The differences in reactivity of three different formula-
tions of peroxides is also clearly indicated in the figure. Lupersol
Delta and Superox-38 are formulations of methyl ethyl ketone
peroxide, the former in dimethylphthalate and the latter as a
water dispersible solution; Aposet 720 is a 'new' fire resistant
ketone peroxide. It should be expected that other formulations
will show similar variations in reactivity.
As would be expected, increasing the amount of aqueous
waste incorporated controls the temperature rise and thus slows
down the reaction significantly. A six-fold increase in time-to-
peak exotherm can be observed in Figure 3 at 1% initiator
(Lupersol Delta) concentration when going from 50% waste to
75% waste in the emulsion. Similarly, the initial temperature of
the emulsion can be changed to control the rate of curing. Both
the initial reaction between peroxide and promoter, and the
subsequent polymerization intiated in the system, are signifi-
cantly dependent on temperature variations around ambient
conditions. For example, the time-to-peak exotherm can be
roughly halved by changing the initial temperature of the
catalyzed emulsion from 30°C to 40°C.
It is interesting to find that the logarithmic plot of the
reciprocal time (to peak exotherm) versus initiator concentra-
tion is linear with a slope close to 0.5 (Figure 4). Since radical
polymerizations typically involve bimolecular terminations
between growing polymeric free radicals, the rates of polymeri-
zation are dependent on the square root of the initiator
concentration.5 The results shown in Figure 4 would indicate
that a typical free radical polymerization reaction is occurring in
i
0)
3 .040
O 60% Nq2S04 WASTE
A 70% Na2 S04 WASTE
E 020 h
I
h
O
X
111
< .010
UJ
.008
SLOPE = 0.54
SLOPE = 0.48
UJ
.006 -
.004
-L
_L
1
_L
0.2
INITIATOR CONCENTRATION, %
Figure 4; Logarithmic Plots Illustrating Dependence of Curing Rate on Square Root of Initiator Concentration.
10
-------
102 Polyester Encapsulation
Table II: Results of Polyester Encapsulation of Hazardous Wastes
Waste type
Di spersion
method
|A1 24% sodium sul-
solution, 30°C
|Ala. 50^ sodium sul-
fate slurry, 40°C
| A lb Dry sodium sul-
fate
|A2 12% boric acid
ptt d, RT
|a3 20% Doric acid
pH 8.4, 50°C
|A7 VR sodium sul-
fate
\7a VR sodium sul-
sulfate
\8 Dehydrated sodium
borate
|A8 VR sodi um
borate
|A9 VR sodium
borate
|ci Heavy metals
mixed organic
waste
|c2 Organic chloride
waste
C3 Organic waste
C4 Pigment sludge
1C5 5% HgCl2
C6 Chloride reagent
waste
|c6a Chloride reagent
neutralized with
NaOH pH 5-12
|C7 Process slurry
C8 Cyanide solution
A
A
A
A
% waste
75
75
resin 22.2
water 33.3
waste 44.4
72
71
resin 25
water 37.5
waste 37.5
75
resin 25
water 37.5
waste 37.5
70
70
40
64
75
69
60
60
72
60
40
Iniatiatoru
and %
SR, H
SR, U
SR, 1%
LD
LO, 2%
SR, H
ID, 4%
LD, 2%
LD, .5*
L0, 1%
LD, 1%
LD, 2%
SR, 2%
SR, 2%
SR 2%
SR, 2%
LD, 4'i
LD, 2%
LO, 2%
LD, 2%
LO-X, 4S
Curing Time to Peak
Temp." C Exotherm
25
25
50
RT
50
25
40
RT
RT
50
RT
50
RT
RT
RT
ST
RT
RT
RT
RT
RT
2 hr.
45 mi n.
40 mi n.
2 hr.
30 mi n.
100 min.
45 min.
10 min.
2 hr.
60
1 hr
2 hr.
60 min.
60 mi n.
30 min.
90 min.
1 hr.
Solidification
behavior
hard set w/o free liquid
hard set w/o free liquid
hard set w/o free liquid
hard set w/o free liquid
hard set with loose
structure
hard set w/o free liquid
hard set w/o free liquid
Time reduced by further
addition of dimethyl
ani 1 i ne
hard set w/o free liquid
hard set
Retarded solidification
reaction; hard set
Retarded solidification
reaction; hard set
Retarded solidification
reaction; hard set
hard set w/o free liquid
highly viscous emulsion;
hard set w/o free liquid
hard set w/o free liquid
hard set; thin layer of
organic liquid on surface|
Phase separation
Phase separation
hard set w/o phase
separation
Solidified with sticky
surface
hard set w/o free liquid
-------
Polyester Encapsulation 103
a. Dispersion methods are designated as
A: Emuls1f1 cation of liquid waste (or slurry) in polyester resin
B: Dispersion of solid waste in preformed water/resin emulsion
C: Dispersion of solid into neat polyester resin.
Table II (cont.)
Waste type
Dispersion
method
% waste
IniatiatorD
and %
Curing
Temp.° C
Time to Peak
Exotherm
Solidification
behavior
C9 Cyanide sludge
A
64
LD-X,
4*
RT
16 mi n.
hard set w/o free
liquid
C10 Kepone sludge
A
50
LD,
2%
50
2 hr.
hard set, rubbery
solid
Cll PCB
C
50
LD,
2%
RT
11 min.
Flexible solid
(plasticized)
C12 Arsenic tri-
ox1 de
C
70
LD,
\%
RT
15 min.
hard set
C13 Arsenic
C
70
LD,
2%
50
30 min.
hard set
C14 Arsenate solution A
60
LD,
2%
RT
100 min.
hard set
b. Initiator concentration based on resin
SR: Superox 38
LD: Lupersol Delta
AP: Aposet
these systems, basically unmodified by the encapsulated sodium
sulfate.
The reactions in the presence of boric acid are more compli-
cated. The acidic solution of boric acid is rather difficult to
emulsify though stable emulsions are formed readily when the
pH is raised by neutralization with sodium hydroxide. Acidic
conditions would thus appear to be unfavorable for formation
of emulsions with WEP. Formation of sodium borate by
neutralization also enables homogeneous solutions of higher
concentrations of borate to be prepared. Generally, the emul-
sions from borate solutions at pH 6-10 were readily solidified at
temperatures around 70° C, as reported earlier.12 However, it
has been found now that, by a proper control of pH and choice
of catalyst, the curing can be done at room temperature or
slightly higher. Stable emulsions and ready encapsulation
resulted when the boric acid was neutralized to pH between 5
and 9. Furthermore, while Superox-38 was capable of produc-
ing a room temperature cure of 12% boric acid neutralized to pH
8, no solidification resulted with this catalyst at pH 10, but
evolution of gas from the reaction medium was observed. Since
this indicated a borate-peroxide reaction in the aqueous phase,
Superox-38 being water soluble, a resin soluble peroxide,
Lupersol Delta or Aposet 720, was employed to keep the
peroxide in the organic phase. Solidification without gas
generation could then be achieved. Thus, even 20% boric acid
neutralized to pH 10 could be encapsulated and solidified with
Lupersol Delta. (Table U)These results are significant in view of
the general observation with water-extended polyesters that
water soluble peroxides are more efficient curing agents.
Mechanical Integrity
The water-extended polyester composites have a compressive
strength approaching that of concrete, and flexural and tensile
strengths corresponding to those of wood. The mechanical
properties vary with the type of catalyst, resin formulation, or
water content.2 The amount of waste incorporated changes
compressive strengths significantly as seen in Table (III). The
measured strength of the solid monoliths are high enough for
safe transportation, storage and land disposal. When low level
radwastes are incorporated, the matrix resin will be subjected to
constant irradiation. The resistance to -radiation of the waste-
polyester composites was therefore determined by exposure to a
Co60 source at the WSU Nuclear Reactor. It is seen from Table
(III) that the compressive strength is in fact increased by gamma
radiation up to a dose of 500 megarads, which is safely above the
doses that can be expected to be received from low-level
radwastes. The increase in strength is probably caused by
additional crosslinking produced in the polymer network by the
gamma radiation. It can therefore be expected that the polyester
matrix can be employed to encapsulate low-level radwastes
without fear of mechanical disintegration of the products
occurring by radiation damage.
Linear shrinkage of cast specimens was measured and found
to reach about 2% in 200 days for a solid incorporating 70%
sodium sulfate waste. The weight loss during storage would
indicate a loss of water vapour by diffusion and evaporation.
Table III: Compressive Strength of 24% Na2S04 Solution
Encapsulated in Polyester Resin
% of
24% Na2S0^ Solution
Y-radiation
(M rad)
Compressive
Strength (N/im2)
50
-
20.9
60
-
15.4
0.42
60
-
9.3
0.34
60
3.8
17.3
0.41
60
7.9
17.4
0.55
60
23.7
18.3
0.38
60
134.0
20.2
0.47
60
326.0
21.4
0.37
60
466.0
22.1
0.41
-------
104 Polyester Encapsulation
90 120
TIME , day
Figure 5: Leachability Curves for Sodium from 24% Sodium Sulfate Encapsulated in Water-Extended-Polyester.
Leachability
The effective immobilization of encapsulated metal wastes by
the polyester process is shown by the typical leachability curve
shown in Figure 5 for the dynamic leaching of sodium ion from
cylindrical specimens prepared by encapsulation of 24% sodium
sulfate solution. The actual amount leached out at the end of 6
months is about 0.2% for specimens containing 50% waste, and
about 2% for specimens containing 70% waste. The surface to
volume ratio of the specimens was 1,85 cm-1. These values,
when extrapolated to the surface to volume ratio for a 55 gallon
drum, viz., 0.095 cm-1, will be0.01%and0.1%respectively. The
results show tha the leachability of the salts encapsulated in the
polyester matrix is 10 to 100 times smaller than that of
specimens obtained in the bitivninization process1 and even
more reduced than those reported for other solidifying agents.9
Static leaching tests gave similar results.
Experiments with radioactive nuclides are underway, using
Sr, Co and Cs isotopes incorporated in sodium sulfate and
borate to simulate concentrations that might occur in actual
radwaste evaporator bottoms (Table I, B1 and B2). Early data
confirm the expected variation of leachability with ion size and
charge. The teachabilities are quite low.
Results of leaching of arsenic and other wastes are discussed
later in the appropriate sections.
VR Sodium Sulfate and Borate
Because of the large volumes of low-level radwastes pro-
duced by the nuclear industry, industrial processes have been de-
veloped for volume reduction (VR) of the liquid wastes. The
typical composition of the end product of these processes is
simulated by wastes A7-A9 in Table I. These solid wastes were
obtained from a company which has developed such a process to
concentrate the solutions to dry solids. It should be noted that
antifoaming agent, motor oil etc., are included in the prepara-
tion of one of these samples, A9, since these components are
present in actual radwastes.
The polyester process of emulsification and solidification of
aqueous waste (method A) was modified to encapsulate solid
residues by two methods; one in which the powder was
dispersed in a preformed emulsion of water-in-polyester
(method B) and another in which the solids were mixed into the
neat resin and solidified (method C). In this manner, VR sodium
sulfate powder was incorporated and solidified readily in
polyester by both methods B and C (Table 11). The mechanical
integrity of products incorporating 75% sodium sulfate by
method B is much lower than that of a product incorporating
65% only. As expected, the curing reaction was much faster in
the neat resin employed in method C than in the preformed
emulsion in method B, but in neither case was there any evidence
of retardation.
VR sodium borate (Table 1, A8) could also be readily
dispersed in a preformed emulsion or the neat resin. However,
the curing reaction was retarded, as observed in the case of
aqueous sodium borates, and the solidification process took a
longer time than with VR sodium sulfate. Further, the presence
of antifoaming agents in the VR sodium borate sample, A9,
caused breakdown of a preformed emulsion when A9 was mixed
into it. No difficulties, however, were encountered in solidifying
A9 in the neat resin (Table II).
-------
Polyester Encapsulation 105
Thus, high proportions of volume-reduced simulated rad-
waste solids could be solidified in the polyester matrix, the waste
to resin ratio being as high when incorporated in a preformed
emulsion as in the neat resin. The leachability from the two types
of products can be expected to be different and is currently
under investigation.
Industrial Chemical Wastes
The chemical wastes that were studied are listed in Table 1.
The actual wastes or waste compositions were received from
various industries in response to our letter soliciting samples of
their wastes that needed safe disposal, particularly those that
were difficult to treat by existing methods. Simulated or
synthesized wastes are clearly identified. The spectrum of wastes
in the table represents some of the most toxic of industrial
pollutants. For example, the hazards of arsenic and cyanide
wastes produced, dumped, stored or awaiting disposal have
been amply documented by EPA." The magnitude of theseand
other hazardous wastes produced have also been summarized in
other reports.11
The results of encapsulation studies with the chemical wastes
are summarized in Table II. While the general applicability of
the polyester process to such wastes is evident from these results,
it is useful to examine the notable features of the behavior of
some systems.
The difficult-to-handle metal finishing industry's waste, CI,
contains hexavalent chromium that is capable of participation
in the reduction-oxidation (redox) reactions between promoter
and initiator. This may partly account for the fact that though
stable emulsions are formed at 50% waste content, they could
not be solidified. Hardset solids are therefore formed only at
40% waste content. The instability of emulsions when the waste
is more than 50% in the emulsions is also worth investigating
further. The paint pigment sludge, C4, contained an organic
liquid which was not, apparently, totally compatible with the
polyester; and a thin layer separated on the surface when 69% of
the waste was encapsulated and solidified. It can be expected
that the separation can be reduced or eliminated at lower waste
contents in the emulsion.
The hazards of the chloride reagent waste, C6, are de-
scribed in a recent publication.14 Because of its high acidity
(pH=0), phase separation occurred even at low waste contents
and stable emulsions could be formed only after neutralization
with sodium hydroxide to pH 4 to 12. These emulsions (C6a)
were cured without difficulty to hard-set solids.
Process slurry, C7, obtained from a disposal industry,
apparently contained components capable of reacting with
water soluble initiators like Superox-38 with gas evolution. Use
of a peroxide soluble in the organic phase (Lupersol Delta)
eliminated this difficulty.
In the case of cyanide solutions, there was clear evidence of
complexing of cobalt in the promoter for the resin by the
cyanide from the waste. An immediate color change to deep blue
on the addition of peroxide initiator indicated the presence of
cobalt cyanide complexes. The reactivity of the promoter,
cobalt naphthenate, originally present in the polyester is thus
modified and at 30% waste in the emulsion, more than 3%
peroxide initiator was needed to achieve proper cure. More
interestingly, there was immediate gelling of the emulsion when
40% cyanide waste was incorporated, followed by cure, without
any addition of peroxide initiator, in about 10 hours. Similar
observations were recorded with cyanide sludge. Color changed
to deep blue when initiator was added to the emulsion and about
4% peroxide was required for cure at room temperature.
Kepone (Allied Chemical Co.,) was obtained as a sludge with
grit, mud and water, etc., present in it. The sludge was stirred up
with water to make a 10% suspension. This was emulsified and
set in the polyester as shown in Table II. At waste contents
higher than 50%, phase spearation occurred. The sludge could
also be dispersed in the neat resin and solidified.
Polychlorobiphenyls, (PCB), obtained from capacitors
supplied by the Washington Water Power Company, formed a
viscous "mixture" after dispersion by vigorous stirring into the
neat polyester resin. The excessive aeration of the mixture
during this process retards the free radical polymerization of the
curing process, apparently because of dissolved oxygen. There-
fore, when the mixing is done under nitrogen, little difficulty is
encountered in solidification and 50% PCB can be solidified in
the polyester in about 10 minutes using 2% Lupersol Delta-X. If
the curing reaction is sloWed down using lower concentration of
peroxide, there is a tendency for separation of liquid PCB from
the mixture before solidification occurs.
The compositions of the arsenic wastes CI2, CI3, C14 were
obtained from a contractor evaluating the quality of products
obtained by different solidification processes applied to arsenic
wastes. Sodium arsenate solutions at 5 and 10% concentration
showed evidence of reaction with the water soluble peroxide
initiator, Superox-38. However, no such reaction or gas
evolution occurred with the organic-soluble peroxides, Luper-
sol Delta or Lupersol Delta-X. One percent solutions could be
emulsified and encapsulated, up to 60% in the polyester, at high
concentrations of peroxide (2%). The curing was evidently
retarded since this took about 2 hours. The fine powder of
arsenic trioxide or the mixture of cacodylic acid with sodium
chloride and sodium sulfate was dispersed into the neat resin
and solidified without difficulty.
The leachability of the toxic components from the encapsu-
lated chemical waste products need to be investigated. Studies
with arsenic trioxide wastes are already in progress. Using
atomic absorption spectroscopy to analyze for arsenic, the
fractional amount leached in 15 days from a product containing
70% arsenic trioxide is found to be about 0.05%. This value is
even less than the 0.2% obtained for sodium from a sodium
sulfate-polyester monolith discussed earlier, and would indicate
that the arsenic is truly immobilized in the polyester matrix.
SUMMARY AND CONCLUSIONS
A new process is now available for immobilization of
hazardous residuals. The simple experimental procedure consits
of (1) dispersing dangerous aqueous wastes in a water extensible
liquid polyester at high shear to form a. waste-in polyester
emulsion and (2) solidifying the emulsion by adding an appro-
priate catalyst which can crosslink the polyester. Aqueous
wastes are thus efficiently encapsulated in individual cells in a
closed cell structure, which facilitates attainment of low leacha-
bility of the waste from the solidified matrix. The mechanical
integrity of the solid products is high and is retained after
exposure to 500 Mrad Y-radiation. The low leachability and
good mechanical properties ensure safety in transportation,
storage and disposal in burial sites of the solidified wastes with
minimal potential for ecosystem contamination.
The process has been successfully applied to low-level
rad waste solutions and a wide spectrum of toxic chemical wastes
such as arsenic, cyanide, PCB, poisonous metals and pharma-
neutical wastes. For solid wastes, the process can be modified to
use the neat polyester resin or preformed emulsion for encapsu-
lation. The interactions of the promoter and peroxide between
themselves and with added wastes have to be carefully studied
and controlled to achieve optimum results by this process with
individual wastes.
ACKNOWLEDGMENT
This paper is based upon research supported by the National
Science Foundation under Grant #ENV76-06583. Any opin-
ions, findings, and conclusions or recommendations expressed
in this publication are those of the authors and do not neces-
-------
106 Polyester Encapsulation
sarily reflect the views of NSF.
REFERENCES
1. Bohr, W., W. Hild and W. Kluger, "Bituminization of
Radioactive Waste at the Nuclear Research Center Karls-
ruhe" Paper presented at the 1974 Winter Meeting of
American Nuclear Society, Washington D.C., October 27-
31, 1974.
2. Carpenter, R. E., "Polyesters, Water-Extended," Encyc-
Jopedia of Polymer Science and Technology, 15, 375(1971).
3. Colombo, P. and R. M. Neilson, Jr., "Properties of
Radioactive Wastes and Waste Containers," Qtly. Prog.
Rep. BNL-NUREG-50617, U.S. Nucl. Reg. Commission,
(Jan. 1977).
4. Conner, Jesse R., "Ultimate Disposal of Liquid Wastes by
Chemical Fixation," Paper presented at the 29th Annual
Purdue Industrial Waste Conference, Purdue University,
West Lafayette, Indiana (1975).
5. Flory, P. J., "Principles of Polymer Chemistry," Cornell
Univ. Press, Ithaca, N.Y. (1953).
6. Hespe, E. D., Ed. "Leach Test of Immobilized Radioactive
Waste Solid," Atomic Energy Review, Vol. 9, No. 1, 195—
207 (1971).
7. Juloori, M. "Semi-Continuous Pilot Plant Studies on
Polymeric Encapsulation of Hazardous Wastes," Thesis,
Washington State University (1976).
8. Landreth, Robert E. and Jerome L. Mahloch, "Stabiliza-
tion of Hazardous Wastes and SOx Sludges," National
Conference on Management and Disposal of Residues
from the Treatment of Industrial Wastewaters, Washing-
ton, D.C. (Feb. 1975).
9. Leonard, J. H., and K. A. Gablin, "Leachability Evalua-
tion of Radwaste Solidified with Various Agents" Paper #4-
-VA/NE-8 American Society of Mechanical Engineers,
Winter Annual Meeting, Nuclear Division, New York
(November ,17-22, 1974).
10. Mahalingam, R., M. Juloori, R. V. Subramanian, Wen-
Pao Wu, "Pilot Plant Studies on the Polyester Encapsula-
tion Process for Hazardous Wastes," National Conference
on Treatment and Disposal of Industrial Waste Waters and
Residues, Houston, Texas, April 26 -28 (1977).
11. Ottinger, R. S., J- L. Blumenthal, D. F. Dal Porto, G. 1.
Gruber, M. J. Santy and C. C. Shih, "Recommended
Methods of Reduction Neutralization, Recovery or Dispo-
sal of Hazardous Waste," Report No. 21485-6013-RU-00,
Vol. 1,(1973).
12. Subramanian, R. V., and R. A. V. Raff, "Immobilization of
Low-Level Radioactive Wastes," 80th National AlChE
Meeting, Boston (Sept. 7-10, 1975); AIChE Symposium
Series, 72, No. 154, 62 (1976).
13. U.S. Environmental Protection Agency, Report to Con-
gress on Hazardous Waste Disposal (1973).
14. Trieff, N. M., F. Gandet and V. M. Ramanujam, American
Laboratory (July 1976), p. 37.
15. Watts, G. Fred and Carlton E. Coats, SPI Reinforced
Plastic/Composites Division, 26th Annual Technical Con-
ference, 12D (1971).
16. Wu, Wen-Pao, "Encapsulation of Hazardous Wastes in a
Polyester Matrix," Thesis, Washington State University,
1977, in preparation.
-------
Pilot Plant Studies on the
Polyester Encapsulation
Process for
Hazardous Wastes
R. Mahalingam, M. Juloori
R. V. Subramanian and Wen-Pao Wu
Washington State University
Pullman, Washington
INTRODUCTION
The disposal of hazardous wastes, e.g., solids, solutions, or
slurries containing toxic compounds of such elements as arsenic,
mercury, selenium, lead, chromium, cadmium, beryllium, etc.,
is a serious problem, the word "hazardous" is used as being
injurious to health. Hazardous wastes must be disposed of in
such a way as to eliminate all danger of their subsequent
contamination of the environment at the disposal sites. In the
current clamor over environmental pollution, increasingly
stringent regulations are being applied over air and water
contamination. Hence, proper land disposal is the most suitable
method of getting rid of dangerous wastes. The problem of safe
disposal of hazardous heavy metals and their salts thus reduces
to one of solidifying them in an impermeable matrix before
disposal. These considerations apply also to the disposal of low-
level radioactive wastes generated by nuclear reactors, and in the
disposal of organic chloride wastes and mixed organic wastes,
phenols, medical wastes, pigment slurries, etc.
This paper reports pilot plant studies of a novel process for
encapsulating and solidifying hazardous wastes in a polyester
matrix. The initial laboratory development and application of
this process for solidifying low-level radioactive wastes was
published recently.9 The successful extension of the process to
immobilize a number of hazardous industrial waste residuals
has also been reported.10 Although the process described in this
paper should thus be applicable to several of the wastes
mentioned above, the initial pilot plant development has been
on simulated (radiation-free) low-level radioactive wastes
typical of those generated by nuclear reactors; and hence a fuller
discussion on these types of wastes is in order.
Low-Level Radioactive Wastes
Although forecasts vary, most show nuclear power as a major
factor in meeting U.S. energy needs by the end of this century.1
The full potential of nuclear power-can be realized only if envi-
ronmentally safe waste disposal methods are developed. While
research and development on ultimate disposal of high level
radioactive wastes is guided by the Atomic Energy Commission,
the disposal of low level wastes is no longer a specific AEC
responsibility. The projected annual quantities of commercial
low-level beta-gamma wastes to be generated by the nuclear
industry by the year 2000 are some 350 million ft3 and these
wastes require burial.2
It is necessary to define quantitatively the meaning of "high,"
"medium," and "low" level wastes. The wastes are classified4
into three groups according to their level of activity:
1. Wastes in the low activity group range from 1*1(M
curie/ml to 1 xl0~n curie/ml.
2. Those of intermediate activity from 1 xlO-1 curie/ml to 1
xlO-' curie/ml.
3. Those of high activity above 10"' curie/ml.
The main sources of radioactive waste waters are:
1. Atomic reactors
2. Isotope laboratories of nuclear research centers.
3. Processing of uranium ore.
4. Laundering of protective clothing worn by personnel
working with radioactive material.
5. Laboratories which use radioactive substances for thera-
peutic, industrial, or other purposes.
In addition, here are two circulating water systems for water-
cooled atomic reactors.
System 1: Demineralized water for direct cooling of radioac-
tive waste material. This water is contaminated due to corrosion
of the pipes and is readioactive to some extent.
System 2: Waterfor indirect cooling in heat exchangers. Heat
is transferred to this water from the System 1. Passage of parts of
the water in the System 1 through ion exchanger columns pro-
duces its activity. Dissociated radioactive compounds are
retained in the ion exchangers. U ndissociated components are
removed continuously as suspensions, or the water may be
replaced by fresh water.4 Thus, the water in the System 2 is
protected from radioactive contamination. However, hazards
may arise if this system is open. If there is corrosion or damage
to the heat exchanger, water from the System 1 could leak into
the System 2. Replacement of the water in the System 1 by fresh
water gives rise to wastes of low activity.4
From a management point of view, there are two main
aqueous waste categories that are of interest:
1. Wastes that cannot be discharged into the environment
and must be isolated from man's environment by a waste
management system such as storage under surveillance.
2. Wastes that can be released to the environment within
existing standards.6
Even though the waste pretreatment and disposal process is
very expensive, it comes to less than 1% of the estimated cost of
making electricity by nuclear power.3 The word "treatment" is
used here to mean manipulation by some chemical or physical
process whereby the original waste is separated into a concen-
trated highly radioactive fraction and a much larger volume of
dilute effluent which often could be liberated to the environ-
ment without hazard to the population. Such processes are
usually applied to "medium level" and "low level" wastes. The
original wastes are often too bulky to be confined economically
in tanks, but contain far too much radioactive material for free
dispersion into the public domain, even in sparsely populated
regions.7
107
-------
108 Pilot Plant Studies
Polyester Process
The following are the principal solidification processes
currently available commercially: a) asphalt, b) cement, c)
cement/clays, d) cement/ silicate, e) urea-formaldehyde. All of
the processes listed above for the encapsulation of low-level
radwastes have certain inherent disadvantages, most important
of them being (1) high leach rates of waste from the solidified
products; (2) non-uniform dispersion of the waste in the
encapsulating medium and (3) high volumes of solidified prod-
ucts.
In the polyester process, simulated (radiation-free) wastes
typical of those resulting from operations of nuclear power
generating stations can be dispersed in water-extensible polyes-
ters to form stable emulsions which can subsequently be set, by
the addition of peroxide initiators, to form lightweight [~0.8 to
1.1 gm/cm3], homogeneous, coherent, rigid, shockproof struc-
tures. When an aqueous waste is dispersed in a water-extensible
polyester resin, the emulsion formed is characterized by a thin
skin of the resin encapsulating the aqueous waste droplets.
When a peroxide is added to the emulsion of an aqueous waste
encapsulated by a polyester resin, polymerization is initiated
and the emulsion gels and cures as the polymerization advances.
The polymerization reaction is explained in Figure 1. In order to
produce a "room temperature setting composition," various
promoters are added to the resin mixture, to accelerate the
decomposition of the peroxide initiator for the production of
free radicals necessary for the reaction. The gel time can be
further reduced by the use of a second promoter, such as a
tertiary amine, in addition to the cobalt compounds. The most
common initiator-promoter combinations are:
Initiator Promoter
1. Methyl ethyl ketone peroxide Cobalt napthenate
2. Cyclohexanone peroxide Cobalt naphthenate
3. Cumene hydroperoxide Manganese naphthenate
4. Benzoyl peroxide Dimethylaniline
The full chemistry and mechanisms involved in these reac-
tions are described elsewhere.' The laboratory studies involving
solidification of hazardous wastes through the polyester process
have been reported.9,10 The present work discusses the transla-
tion of the laboratory work into the pilot plant stage.
Preparation of Unsaturated Polyester
H02C - CH = CH - COzH + HO - (CH2)2 - OH
(dicarboxylic acid*) (ethylene glycol )
0 0
^~O-(CH2)2-(0-C-CH=CH-C-0-(CH2)2-0
Crosslinkinq of Polyester
Promoter*Initiator-*-Free Radicals ~u
0 0 CH=ch2
^0-C-CH=CH-C-0-(CH2)2-~+ Q
(unsaturated polyester resin) styrene (monomer)
free radicals 0 sty**0
»- ~~0 - C - C H - CH - C - 0 ~ (CH2>2
CH-CH - CH-CHZ'
it
els-configuration. maleic acid
trans - configuration-, fumoric acid
-.6 p
CH - CHZ~
n
Figure I: Polymerization Reactions Involving Unsaturated
Polyesters and Monomers
Pilot Plant Construction
The pilot plant (Figure 2) has been constructed with the idea
of achieving the immobilization of various types of wastes in
three distinct steps:
Step 1: Batchwise preparation of the waste solution or slurry
in an aqueous medium.
Step 2: Continuous emulsification by continuous, simultane-
ous addition of the waste solution/ slurry and the encapsulating
polymer resin into a pre-formed emulsion of the same waste-to-
resin ratio.
i runt, view
Figure 2: Polyester Encapsulation Process for Hazardous
Wastes—Pilot Plant
-------
Pilot Plant Studies 109
COMPRESSED
AIR
SED I 1 9 9
WASTE
MATER|AL
WATER
STEAM
(19)
INITIATOR
Legend
1.
Waste Preparation Tank
11.
Steam Coil
2.
Steam Coil
12.
TM
Variable-Speed Turbon Mixer
3.
3-Speed "Lightnin" Mixer
13.
Air Motor
4.
Rotary Screw Pump
14.
Rotary Screw Pump
5.
Air Filter
15.
Overhead Resin Tank
6.
a,b 4-Way Solenoid Valves
16.
Resin Metering Pump
7.
a,b,c,d, Diaphragm Valves
17.
Timer
8.
Flow Control Valve
18.
Solidification Can
9.
Rotameter
19.
Variable-Speed Disposable Mixer
10.
Emulsification Tank
Figure 3: Pilot Plant Flow Sheet—Polyester Encapsulation Process for Hazardous Industrial Wastes
-------
110 Pilot Plant Studies
Step 3: Solidification of the emulsion in small-volume cans by
emulsion transfer from Step 2, on a sequential basis, followed by
initiator addition.
In the following discussion, reference is made to the Process
F low Sheet (Figure 3). A 50-gallon stainless steel drum (Waste
Preparation Tank (1)), is used for the preparation of either the
waste solution or the waste slurry. This tank is fitted with a
copper immersion coil (2) for purposes of steam heating, and a
top-mounted, three-speed mixer with a three-blade marine
propeller (3).
The bottom discharge of (1) is connected to the suction of a
rtftary screw pump (4) driven by a %-HP TEFC permanent
magnet DC motor and an SCR speed controller. The pump has
a Buna-N stator. The discharge from this pump is directed in
either of two directions by two diaphragm valves (7a,b). These
'/rinch valves have 316 ss body and an ethylene-propylene
copolymer diaphragm and are operated pneumatically by a 4-
way, explosion proof, solenoid valve (6a). The diaphragm valves
used here are for on-off service and are of the "air-to-open and
air-to-close" type. All the process lines are }A inch o.d. copper
tubing while the compressed airlines are 3/« inch o.d. The control
valve (8) is located on the recycle line rather than on the
rotameter line in order to achieve better flow control.
The emulsification tank (10) is a 12.5 gallon aluminum tank,
also fitted with a steam immersion coil (11). This tank has a top-
mounted mixer (12) of stainless steel, with a mixing head of
special design (Turbon™* Mixer Head, Model A, Figure4). The
mixing action of the head is described as follows.8 Axial and
radial material mixing action yields efficient high rates of
circulation. Internally a rapidly rotating frusto conical member
iroduces a powerful pumping action which draws material into
the central mixing chamber from both ends. An intense
hydraulic shearing action results where the materials meet each
other. The mixed material is then expelled through the slots in
the mixing chamber by centrifugal force creating a strong
mechanical shearing action. Additional hydraulic shearing
occurs as the jet streams of discharged material impinge against
the slower moving masses outside. As material is discharged, a
suction is created which draws into the mixing chamber more
material, repeating the mixing action. The mixer is driven by an
air motor, the speed control being achieved by varying the
operating air pressure/ flow.
The encapsulating resin received from the supplier in 55-
gallon drums, is usually stored in the cold room and required
quantities are transferred to the overhead neat resin tank (15), as
needed. This overhead tank is of stainless steel and is of 12.5
gallon capacity. A stainless steel metering pump (16) of the
piston-type, driven by a V2-HP explosion-proof motor, is used to
meter the neat resin into the emulsification tank (10) through 3/s
inch copper tubing.
The bottom discharge of the emulsion tank (10) is connected
to a rotary screw pump driven by a V2-HP, explosion-proof
motor and a 5:1 gear reduction unit. The discharge from this
pump is directed to the solidification unit or recycled by
operation of the V2 inch diaphragm valves (7c) and (7d). The
action of the solenoid valve for the diaphragm valves is
controlled by a timer unit (17) of the rotating disc, microswitch
type.
The solidification unit consists of either one gallon or one-half
gallon paint cans (18), with facilities for mixing the contents
with a variable speed laboratory mixer (19), the shaft and
mixing head of which are made of Lucite. No special unit has
been designed for the initiator addition.
Temperature measurement of the contents in (1) and (10) is
made possible by sheathed immersion thermocouples connected
* The Turbon1" Centrifugal Mixer is marketed by Tobert Industries
Inc., Southbridge, MA.
to dial temperature gauges. A 24-point millivollstrip chart rec-
order with copper-constantan thermocouples is used for rec-
ording the time-exotherm temperature profile during the
solidification process. A Brookfield viscometer (Model RVT) is
used for monitoring the viscosity changes during the emulsifica-
tion. A stroboscope is used for RPM measurements of the air
motor.
L.C.OCINU j2) pruS}0 conical Section
(3) Slotted Cylindrical Cage
(4) First Stage - Centrifugal Suction
(5) Second Stage - Shear
(6) Third Stage - Shear
Figure 4: Turbon™ Mixer Head (Model A)—Parts and Flow
Pattern
Pilot Plant Operation
A general description of the runs is given below. The aqueous
waste solution/slurry, about 10-20 gallons, is prepared in (1)
and brought and maintained at the desired temperature.
Maintaining the recycling aids in solution preparation and in
obtaining better flow control through rotameter (9), however,
this recycle is now through the recycle line past diaphragm valve
(7b).
In the initial runs, waste solution and neat resin additions to
the emulsification tank (10) are started simultaneously. The
waste solution flow is monitored with the rotameter while the
resin addition is regulated by the metering pump (16). Simul-
taneously, in order to provide good mixing, pump (14) is started
with the diaphragm valve (7c) on the recycle line being open
while valve (7d) is kept shut. When the emulsion level in (10) has
built up sufficiently to cover at least half the mixer head, the
mixer (12) is started and the speed adjusted to anywhere from
1,500 to 2,500 RPM. The phase separation characteristics and
the viscosity of the emulsion are monitored from the start, by
collecting samples from the recycle line every few minutes, to
give an indication of the stability of the emulsion to establish
when canning and solidification could be commenced. As soon
as a stable emulsion appears to be formed, the rotating disc
timer is started to keep open diaphragm valve (7d) and keep shut
-------
Pilot Plant Studies 111
Table I: Results for Runs with Sodium Sulfate Waste Solutions
Run •#
1
2
3
4
11
Waste used
Sodium Sulfate
207; by weight
Sodium Sulfate
20!! by weight
Sodium Sulfate
202 by weight
Sodium Sulfate
20% by weight
Sodium Sulfate
24% by weight
Resin used
Aropol WEP
661-P
Aropol WEP
661-P
Aropol WEP
661-P
Aropol WEP
661-P
Aropol WEP
661-P
Planned waste-
to resin ratio
in the final
solid
50:50
60:40
60:40
65:35
70:30
Initiator used
Lupersol Delta
Lupersol Delta
Lupersol Delta-X
Lupersol Delta-X
Lupersol Deita-X
Temperature of
waste solution,
°C
25
43
43
32
40
Temperature of
resin, °C
20
20
20
20
20
Temperature of
emulsion, °C
18-21
32-34
23-29
25-28
27-31
Flow rate of
waste solution,
al /rain
480
480
563
840
420
Flow period for
rfaste and resin,
nin.
42
30
42
46
89
Flow rate of
resin, ml/min
540
470
400
53^
208
Time for emulsi-
fication, min.
40
55
15
21
10
"Turbon" mixer
speed, rpm
790 for 10 min.,
then 1700
1700
2400
1875
1900
Canning cycle
time, min.
3
3
6
6
6
Canning time per
can, sec.
30
30
46
46
46
Amount of initia-
tor per can, ral
5-35
30
30
20
5-25
Duration of nixin
in can, min.
5
0.5
1.5
2
2 (for cans 1-4)
3 (for cans 5-8)
3 (for cans 1-7)
2 (for cans 8-13^
Total number of cans 12
13
S
8
13
Density of waste,
gm/nl
1.20
1.20
1.20
1.20
1.215
Density of resin,
gm/mi
1.02
1.02
1.02
1.02
1.02
Haste to resin ratio
(wt basis) achieved 52:48
Results
56:44
56:44
67:33
70:30
Quality of
emulsion
uniform, viscous
but unstable
uniform viscous
but unstablp
uniform, viscous
and stable
uniform, viscous
and stable
uniforra, viscoui
and stable
-------
112 Pilot Plant Studies
Table I (cont.t
Run #
11
cnange m coior
of emulsion after
mixing initiator
with it
white to light
b rovn
white to light white to light
brown brown
Initiator cor.cen- 1.13-7.10
tration, gm/100 gm
of resin in emul-
sion
peak temperature.
°C
time to reach
peak exotherm,
min.
characterist ics
of the solidified
product
not measured
not measured
encapsula t ion
and mechanical
integrity not
good. Good
curing and hard
product. Ap-
pearance is net
uniform. Free
water and free
sodium sulfate
on surface. Low
density (1.15-
1.22 gra/cc)
2.39-A. 34
67-97
14-69
encapsulation
and mechanical
incegrity not
good. Good
curing and hard
product. Ap-
pearance is not
uniform. Free
water and free
sodium sulfate
on surface. Low
dens ity (1.11-
1.20 gm/cc)
1. 73-2.18
73-100
white to light
b rown
1 . 70-2.03
white to light
b rowr.
0.82-5.57
20-30
good encapsula-
tion and good
mechanical in-
tegrity. Good
curing and hard
product. Uni-
form appearance.
Neither free
water nor free
sodium sulfate
on surface. Low
density (1.15-
1.21 gm/cc)
72-80
26-36
good encapsula-
tion and good
mechanica1 in-
tegrity. Good
curing and hard
product. Uni-
form appearance.
Neither free
water nor free
sodium sulfate
on surface. Low
dens ity (1. 16-
1.20 gm/cc)
76-86
25-46
good encapsula-
tion and good
mechanical in-
tegrity. Good
curing ar.d hard
product. Uni-
form appearance
Neither free
water nor free
sodium sulfate
on surface. Low
density (0.94-
1 . 10 gra/cc)
Table II: Results for Runs with Boric Acid Waste Solutions
Run #
5
6
7
e
9
10
Waste used
Boric acid
(121 by wt)
Boric acid
(12% by wt)
Boric acid
(20t by wt)
Boric acid
(12% by wt)
Boric acid
(20i by wt)
Boric acid
(20* by wt)
pH of waste
8 05
7.94
10
6
9.95
8.20
Resin used
Planned waste to
resin ratio (wt
basis) in the
final solid
Aropol WEP
661-P
60: 40
Aropol WEP
661-P
65: 35
Aropol WEP
661-?
55:45
Aropol WEP
661-P
65:35
Aropol WEP
661-P
65: 35
Aropol WEP
661-P
65; 35
Initiator used
Lupersol
Delta-X
Lupersol
Delta-X
Lupersol
Delta-X
Lupersol
Delta-X
Lupersol
Delta-X
Luperso1
Delta-X
Temoerature of
waste, °C
46
25
80
49
65
40
Temperature of
resin, °C
20
20
20
20
20
20
Temperature of
emulsion, °C
26- JO
20-37*
33-43
30-36
40-46
29-33
Flow rate of
waste, ml/min
575
670
575
700
575
635
Flow rate of
resin, ml/min
50 0
380
360
368
356
380
Flow period for
waste and resin,
min.
46
34
24
33
38
46
Time for emulsl-
fication, min.
15
15
40
20
30
15
"Turbon" mixer
speed, rpm
2740
1875 for 5
min, then 2275
1775
2270
2300 for 15
min, then 100
2300
-------
Pilot Plant Studies 113
Table II (cont.)
Run #
5
6
7
8
9
10
Canning cycle
t i me, m i n.
6
*
* *
« *
* *
6
Canning time per
can, sec.
46
»
* *
• •
46
Amount of
initiator
added per can, ml
10-20
10
10-20
5-10
15
10-25
Duration of mixing
in can, min. 3
3
3
3
3
3
Total number
of cans
12
7
6
6
4
13
Density of waste,
gm/ml
1.01
1. 08
: .30
1.01
1.19
1.107
Density of
resin, gm/ml
1 . 02
1.02
1.02
1 .02
1.02
1.02
Waste to resin
ratio (wt basis)
achieved
33:47
64 36
56:44
68 : 32
€6: 34
66 : 34
Quality of
emulsion
good, uniform,
stable,
v i SCOUB
good, uniform,
stable
highly viscous
not good,
not uniform,
not stable
good, uniform
stable,
viscous
not good,
not. uniform,
uns tab1e
good, uniform,
stable,
viscous
Change in color
of emulsion
after mixing
i ni ti ator with it
white to
dark brown
white to
dark brown
white to
brownish
green
white to
brown
white to
brownish
g reen
white to
brown
Initiator
concentration,
gm/lOOgm of
res in in
emu 1sion
1.43-2.84
1. 24-2 10
1.36-3.81
1.16-2.42
1.91-4.14
1.63-4.59
Peak temperature,
oc
88-93
42-66
50-75
• * *
61-69
Time to reach
peak exotherm,
mm
26-40
37-105
* • »
37-80
• * *
55-92
Characteristics
of the solid-
ified product
good encap-
5 u la tion and
good curing.
Hard product
with good mech-
anical integ-
rity. Uniform
appearance.
Neither free
water nor free
boric acid on
su rface. Low
density (0.67-
0.94 gm/cc)
good encap-
sulation and
good curing.
Hard product
with good mech
anical integ-
rity. Uniform
appea ranee.
Neither free
water nor free
boric acid on
surface. Low
dens i ty (0.97-
1.07 gm/cc)
encapsulation
not satisfac-
tory and cur-
ing not suf-
- ficient. No
mechan ica1
integrity.
Water at the
bottom of Cans
Soft product,
became slight-
ly hard after
a few weeks.
good encap-
sulation and
good curing.
Hard product
with good mech-
anical integ-
rity. Uniform
appea ra nee.
. neither free
water nor free
boric acid on
surface. Low
density (1.05-
1.14 gm/cc)
encapsulation
not satisfac-
tory and cur-
ing not suf-
ficient. No.
mechanica1
integrity.
Water at the
bottom of cans.
Soft product,
became slight-
ly hard after
a few weeks.
Low density.
good encap-
sulation and
good curing,
hard product
with good mech-
anical integ-
rity. Uniform
appearance.
Neither free
water not free
boric acid on
surface. Low
density (1. 11-
1.19 gm/cc1
•the emulsion was heated using steam
*"canning
was carried out manually and the
cycle times and
filling periods were not measured
••"the peak
temperatures and
exotherm temperatures were very close to the emulsion temperatures and hence peak
the corresponding setting times are not reported
exotherm
valve (7c) for during one of the following time periods—30,45,
or 60 seconds—every 3 or 6 minutes. Thus, the emulsion is
directed to the solidification can (18) every 3 or 6 minutes, as the
case may be, with a filling time of 30,45, or 60 seconds. During
the fill period, an initiator is added to the can (~ 1% by weight of
the total contents of the can) and the disposable Lucite mixer
(19) started and allowed to run for about two to three minutes
over and above the fill time. By this time, valve (7d) is ready to
open for the next fill cycle. The filled can is next removed and
placed near the temperature recorder unit with two/three
thermocouples inserted at various depths to measure the
solidification temperature-time profile and the peak solidifica-
tion temperature.
In subsequent runs, an emulsion is initially prepared in (10) to
about one-third of the tank height, by addition of the required
quantities of the resin and waste streams, the resin stream
preceding the waste stream, the mixing being effected by both
pump recycle and "Turbon" mixer operations. As soon as the
emulsion is ready, simultaneous addition of the two streams
begins for continuous operation and commencement of canning
cycle. The approach described in this paragraph would corres-
pond more closely to the sequence of operations in a full-scale
-------
114 Pilot Plant Studies
commercial unit. Description of some typical individual runs is
given below. Run #3 for sodium sulfate and run #5 for boric acid
are discussed at length. A general summary of the results from
runs I through 11 is presented in Tables 1 and 11.
Sodium Sulfate Runs
Runs 1, 2, 3, 4 and 11 describe the runs with model sodium
sulfate wastes. For example, the sequence of operations per-
formed in run #3 is shown in Figure 5; the details pertaining to
this run are given in Table I. The emulsification operation in this
run is somewhat different from those in runs 1 and 2, in the sense
that waste and resin streams were fed to a pre-formed waste-in-
resin emulsion as opposed to the addition of resin and waste to
the empty emulsification tank (10). Lupersol Delta-X, * the
initiator, was added to the emulsion during the canning period
and the contents of the can were mixed well for two minutes.
. resin feed
. 0 t ime
recycling started—
("Turbon mixer started
i (2400 rpm -
* Sample # I ~*j
5 -H
commenced j (Q
Iresin_st rea m stopped ;
[waste feed commenced1
resin feed
10 mi n
started again
can # I
feed 1
Jstreams i
stopped J
canning
19 min
~ 7
. 6
I I min
44 min
* Emulsion sample collected for viscosity
measurements L J
Figure 5: Experimental Details for Run #3
resin feed
0 time
commenced r
I 12 min
resin streom stopped f
[waste feed commenced^
iresin feed storied
|*aqain i
12 min
2.min
14 min
can #1 j
r feed
1 (1 streams
(stopped
canning
- 3
*¦ 5
r
• 9
17 min
54 min
recycling started
fTurbon mixer
| started(2740rprrir
* sample # I -<
—j
3-
—(
5 -i
7 -
H
9-1
I I
l33
15 -M
16
* Emulsion sample collected for viscosity
measurements
Figure 6: Experimental Details for Run #5
* Registered trademark of Lucidol Division of Pennwalt Corporation
for 60% methyl ethyl ketone peroxide in dimethyl phthalate.
Boric Acid Runs
Runs 5, 6, 7, 8, 9 and 10 describe the runs with model boric
acid wastes. Run #5 is identified here. A 12% by weight solution
of boric acid was prepared and the pH of this solution was
adjusted to 8.05 at 46°C by the addition of sodium hydroxide.
The sequence of operations performed in this run is depicted in
Figure 6. The details pertaining to this run can be seen in Table
11. Initiator was added to the emulsion during the canning
period and the contents of the can were mixed well for 3 minutes.
(f)
o
u
(f)
¦Z
UJ
a:
<
a.
a.
<
Brookfield Viscometer ( Model RVT, Spindle # I )
o Speed = 20 rpm
~ Speed = I 0 rpm
A Speed = 5 rpm
120 130 140
feed streams stopped
20 30 40 50
60 70 80 90 100 110
TIME (min)
can# i 2 3
Figure 7: Apparent Viscosity vs l ime Elapsed Since the
Commencement of Emulsification Run #3
(fi
o
o
cn
UJ
a:
a.
CL
<
Brookfield Viscometer (Model RVT,Spindle #J)
0 Speed = 10 rprr
o Speed - 5 rpm
A Speed - 2.5 rpm
O Speed = I rpm
feed streams stopped
—i 1—J—j—i 1 1 * ¦ i i i i j
0 10 20 30 40 50 60 70 80 90 100 HO 120 130 140
TIME (min)
can #
2345 6789 10
Figure 8: Apparent Viscosity vs Time Elapsed Since the
Commencement of Emulsification—Run #5
Viscosity Behavior
Figures 7 and 8 show the viscosity variation with time for the
emulsion in the tank (10). The figures also indicate the can
numbers corresponding to various times as well as the duration
of addition of the feed streams. Because of the non-Newtonian
character of the emulsion, the shear stress-shear rate of the
emulsion at various times (refer to can numbers or sample
numbers) are shown in Figures 9 and 10. Curves such as these
and the viscosity-time curves have been prepared by following
the course of each run, for all runs. It is obvious that viscosity
behavior is an important parameter in the emulsification/ solidi-
fication operation, as will be seen further in the discussion
section.
-------
Pilot Plant Studies 115
I03
8
6
4
3
<
a:
tr
<
LlI
X
V)
I02
8
6
<>
I01
I01
3 4 6 8 I02
SHEAR STRESS (dyne/cm2)
Figure 9: Rheological Behavior of Emulsion -Run #3
I0;
<
tx.
tr
-------
116 Pilot Plant Studies
Table 111: Temperature-Time Profile during Polymerization-
Emulsions from Run #3
Gms o f
Initiator
Added Per
100 grr of
Resin in
Canned
;anlEmuls ion
Thermocouple Q Level
Time to
Reach
Peak
Exothe rm
Ml n
1~ Thermocouple @ Level 2'
Peak
Exotherm
Temperature
°C
3-1
|3-2
3
3-4
3-5
3-6
3-7
3-8
2. 17
1 . 78
1 . 73
2. 02
2 .01
1.92
1. 98
2.01
24
24
27
2 c
22
2 6
2 2
27
78.3
94 . 7
97 . 8
100
98
is
97
98
T iff>« "to
Reach
Peak
Exotherm
M i n
26
28
27
17
22
29
22
30
Peak
Exothe rm
T empe r ature
°C
88.3
99 . 3
99 . 4
99 . 7
98 . 9
100 . 0
87 . 5
98 . 9
Thermocoup 1 o_(3 level 3*
Time to
Reach Peak
Peak Exotherm
Exotherm Temperature
Min OC
30
90.6
20
90 . 6
21
97.2
20
87 . 6
23
95.6
24
95 . 3
24
97.8
25
98.3
Table IV: Temperature-Time Profile During Polymerization—Emulsions from Run #5
Thermocouple y Level 1* Thermocouple (•' Level 2'
Gnus of
Init i a tor
Added Per
10 0 gni of
Resin in
Canned
Emulsion
Time to
Reach
Peak
Exotherm
Min
Peak
Exotherm
Temperature
°C
5-1
J . 86
30
5-2
2. 33
28
5-3
2. 44
27
5-4
2 . 50
27
5-5
2. 62
28
5-6
2 . to 6
2 6
5-7
2. 75
2 0
5-8
2. 84
2 6
5-9
1 . 4-3
4 0
5-10
1.43
38
5-U
2. 21
31
5-12
2.2 5
31
90 .
93.
91.
90 .
91.
90 ,
SO ,
9 0
8 8
88
9 1
90
0
3
7
6
1
8
8
6
I
3
1
8
Time to
Peach
Peak
Exotherm
Min
32
28
29
31
30
30
30
26
44
43
3 3
3 5
Peak
Exotherm
Tempera ture
°c:
8 0 ,
74
6 4
60
55
55
55
50
5 3
54
58
51
0
4
4
6
3
3
3
7
3
4
6
7
* Level
Level
1:
2:
Bottom of can
7.6 cms above bottom of
can
# 13 from run 11, revealed that there was no noticeable differ-
ence between the curing of emulsion in the closed can and that in
the open-top cans. Figure 11 shows the exotherm temperature-
time profile in the solidification cans after the addition of the
initiator to the emulsion. The peak temperature may be taken as
the one corresponding to the solidification point. The corres-
ponding time is the time required for solidification of the
emulsion for a given initiator concentration. The total number
of cans is shown to be anywhere from eight to thirteen (see Table
I), for each run; this number limitation is based on economy.
-------
Pilot Plant Studies 117
Run t? 3(Can it 2,Thermocouple
at Bottom of the Can)
Run# 4(Can 2,Thermocouple
_ at Bottom of the Can)
Run#l)(Can 3, Thermocouple at
Bottom of Can)
Run 2 (Can ^-1! at I!.4cm
From the Top of the Can )
O 10 20 30 4 0 50 60 70 8 0 90 100 HO 120 130 140
Time (mm)
Figure 11: Temperature-Time Profile During Polymerization-
Sodium Sulfate Runs
Thermocouple is at the Bottom of the Can
in Each Run
Run $ 5 ( Can #3)
y—[; Run ft tO (Can # 3 )
Run#6(Cantrl)
O 120 130 140
50 60 ro 80 90
Time(min)
Figure 12: Temperature-Time Profile During Polymerization—
Boric Acid Runs
The usual procedure was that, after this number of cans were
filled, the remaining material from the emulsification tank was
dumped into a lined garbage bin for solidification and disposal.
Due to the low density of the encapsulating polyester resin,
the solidified wastes are also of low density (0.94-1.2 gm/cc).
Boric Acid Runs
The discussion of results from the boric acid runs is somewhat
similar to that for the sodium sulfate runs. It can again be seen
from the results presented that the pilot plant is capable of
achieving the planned waste/resin ratios in the final solidified
product.
The emulsions were uniform, viscous, and stable in all but two
runs; these two runs (runs 7 and 9) were with 20% (by weight)
solutions of boric acid at about a pH of 10; moreover, the
emulsions in these two runs were at relatively higher tempera-
tures in comparison with other boric acid runs; also, in these
runs emulsification times were somewhat higher than in the
other four runs (runs 5,6,8, and 10). The emulsion in run 6 was
rather more viscous than in other runs, probably because of the
low temperature of the emulsion, initially.
Figure 8 shows viscosity of the emulsion in run 5 reached
almost steady values rather rapidly. The changes in viscosity of
the emulsion for run 6 were observed to be more dependent on
temperature than on changes in shear rate. In run 10, the first
two samples of emulsion for viscosity measurements were
collected prior to obtaining the pre-formed emulsion of the
desired composition of waste and resin. Viscosity of the
emulsion in Run 10 gradually decreased with decreasing shear
caused by the accumulation in the emulsification tank prior to
stopping the feed streams and it increased in a similar fashion
with increasing shear caused by depletion in the tank due to
continued canning, in spite of the stoppage of feed streams. This
would then indicate the dilatant nature of the emulsion. For the
emulsions in runs 5 through 10, a logarithmic plot of shear rate
versus shear stress is a straight line having a slope that is greater
than unity, which implies the dilatancy of the emulsion.
Based on the hardness and appearance of the solidified waste,
curing of polymerization initiated emulsion was good forallthe
runs with boric acid except for runs 7 and 9. In runs 7 and 9
curing was very unsatisfactory and very slow, due to reasons
mentioned above. The setting times for runs 5, 6,8, and 10 were
of the order of 26-105 minutes depending upon several factors
such as the concentration of initiator used, temperature of the
emulsion, dispersion of initiator in emulsion (Table II). The
corresponding exotherm peak temperatures were anywhere
from 42 to 93°C (without any ebullition), again depending upon
the factors such as those mentioned above. As in the case of
sodium sulfate runs, it may be said that there was no significant
difference in the curing of emulsion in the closed can (in run 10)
from that of the emulsion in the open-top cans. Figure 12 shows
the exotherm-time profile in the solidification cans after the
addition of the initiator to the emulsions. The temperature rise
was rather rapid in the case of emulsions in runs 5 and 8. Howev-
er, there was no significant temperature rise in the case of runs 7
and 9. Perhaps, either the initiation was considerably reduced
due to the probable decomposition of dimethylaniline, the
promoter added to the polyester resin by the manufacturer, at
the high temperatures of emulsification with the waste solution
or the polymerization reaction might have been inhibited by a
rather high alkalinity of emulsion containing waste solution of
pH at about 10.
The encapsulation in runs 5, 6, 8, and 10 was observed to be
very good based upon visual examination of longitudinal
sections. However, it was not so good for runs 7 and 9 as could
be judged by the presence of free water on the surface of set
emulsions. For the boric acid runs, too, the solidified wastes
were of low density (—0.9-1.2 gm/cc).
The characteristics of the emulsions encountered in these six
runs with boric acid waste solutions and their curing and
encapsulation of wastes by the polyester network seem to be
more based on pH of the waste than on concentration of the
dissolved solids present in emulsion or on concentration of the
waste solution in the emulsion. Compare run-5 or 6 with run 10
for concentration of dissolved solids in the waste solution with
pH being very close for them. Again, compare run 7 or 9 with
run 10 for pH of the waste solution with concentration of the
dissolved solids in the waste being the same and especially for
runs 9 and 10 the main difference was pH of the waste solutions
only.
Leaching tests are being conducted on the solidified material
and the results will be presented separately. However, the leach
rates are expected to be much lower than those with material
solidified through other processes. This is based upon the results
obtained with laboratory scale tests.10
The results from the runs with sodium sulfate and boric acid
establish the high potential for the commercial success of the
process.
CONCLUSIONS
Both sodium sulfate and boric acid waste solutions can be
emulsified and solidified in a polyester matrix in a semi-
continuous pilot plant in proportions of up to 70% for sodium
sulfate solutions and 68% for boric acid solutions. The process
parameters that are important to be controlled in the emulsifica-
tion step are: temperature of the waste, temperature of the
emulsion, shear rate used in the emulsification and viscosity of
the emulsion, and pH.
-------
118 Pilot Plant Studies
In the extrapolation of laboratory results to the pilot plant, as
determined by the successful encapsulation of sodium sulfate
and boric acid wastes, our studies have been able to identify
problem areas that culd be expected in a full-scale commercial
development; these are:
1. Maintenance of a minimum temperature required to
prevent the waste solution from becoming supersaturated;
2. Evaporation of the waste at high temperatures;
3. Evaporation of the styrcnc present in the resin during the
cmulsification operation at high temperatures (at about 80°C);
4. Maintenance of a steady flow rate of waste stream,
particularly at high temperatures (about 80°C); and
5. Formation of highly viscous emulsions and pumping
thereof.
It should, however, be pointed out that these problems are not
insurmountable. The encapsulation could be carried out either
batchwise or continuously and either as small volume or as large
volume. The emulsions formed are seen to be dilatant.
REFERENCES
1. A National Plan for Energy Research, Development and
Demonstration: Creating Energy Choices for the Future
1976. Volume I: The Plan, ERDA, Washington, D.C.
(1976).
2. Blomeke, et al. Projections of Radioactive Waste to he
Generated by U.S. Nuclear Power Industry. ORNL-TM-
3965, Oak Ridge National Laboratory (February 1974).
3. Clarke, J. H., and Wright, T. D. "The Treatment of
Radioactive Liquors by a Single Stage Phosphate Ferro-
cyanide Chemical Treatment." AERE Report. EIarwell(in
script)
4. Dieterich, B. "F.ntstehung, Eigenschaften, Wiederverwen-
dung und Behandlungvom Radioactiven Wasser." Berichte
der Abwassertechnischcn Vereinigung 2, 365 (1958)
5. Juloori, M., M.S. Thesis, Washington State University,
Pullman, Washington 99164 (1976).
6. Kearney, M. S., and Walton, R. C., Jr. "Long-term
Management ot High-l.evel Wastes." Chemical Engineer-
ing Progress 72,61 62 (March 1976).
7. Mawson, C. A. Management of Radioactive Wastes.
Princeton: New Jersey: Van Nostrand Co. (1965),
8. "Simoitds Turbon Centrifugal Mixer" (catalog No. 14),
lobert Industries, Inc., 125 Marcy St., Southbridge,
Massachusetts 01550.
9. Subramanian, R. V., and Rail, R. A. V. "Immobilization of
Low-l evel Radioactive Wastes," 80th National AlChE
Meeting, Boston (September 7-10, 1975); AlChE Sympo-
sium Series 72, f? 154,62 (1976).
10. Subramanian. R. V., Wu, Wen-Pao, Mahiilingam, R„ and
Juloori, M., Polyester Encapsulation of Hazardous Indus-
trial Wastes," National Conference on Treatment and
Disposal of Industrial Waste Waters and Residues, Hous-
ton, Texas (April 26-28, 1977).
ACKNOWLEDGEMENT
This research was supported by the Nat ional Science Founda-
tion under grant no. ENV76-06583. Jay Backus and Fuad El-
Haggagi assisted in some of the experimental runs. Any
opinions, findings, conclusions or recommendations expressed
in this publication are those ot the author(s) and do not neces-
sarily reflect the views of the National Science Foundation.
-------
Hydrogen Peroxide
for Industrial
Wastewater
Pollution Control
W. G. Strunk
Industrial Chemical Division
FMC Corporation
Princeton, New Jersey
INTRODUCTION
Hydrogen peroxide has been a commodity chemical for many
years and about 200,000,000 pounds are produced annually in
the U nited States. It is marketed industrially as a water solution,
usually at concentrations of 35 or 50 wt. % hydrogen peroxide.
In applications suited to bulk quantities, it is transported at a
concentration of 70 wt. % and diluted to the desired concentra-
tion at the consuming location. For uniformity and to avoid
possible confusion, hydrogen peroxide usage is generally
expressed in terms of the 100% material. This nomenclature will
be followed throughout this paper.
Most people are familiar with the 3% drug store peroxide used
as a treatment for minor cuts and abrasions. Some use 6%
cosmetic hydrogen peroxide to change the shade of their hair
and the term "peroxide blond" has become part of our
vocabulary. A major portion of the hydrogen peroxide pro-
duced is used industrially for bleaching operations in the paper
and textile industries. It is used in the chemical industry as an
epoxidation agent and an oxidizing or reducing agent. Other
applications for hydrogen peroxide include ore and metal
treatments, and gas generation for such exciting applications as
submarine propulsion and attitude control in space vehicles.
Several years ago, as environmental concerns became
intensive and widespread, the use of hydrogen peroxide devel-
oped initially to destroy sulfide odors1 and later to improve
certain other aspects of wastewater treatment. The other
wastewater treatments include: correction of sludge bulking2>-V>
destruction of phenol5'6' source of supplemental oxygen7, and
the oxidation of a variety of reduced sulfur compounds8. These
uses will be described in a summary fashion for operating
situations. Currently about 100 municipal industrial locations
are using hydrogen peroxide in wastewater treatment opera-
tions.
Sulfide Odor Control
Sulfide may occur in wastewater as a chemical waste or as a
by-product of industries such as tanning, oil refining or pulping
operations. It may also be formed in wastewater when sulfates
are reduced by anaerobic, sulfate-reducing bacteria. Sulfide in
wastewater may volatilize into the atmosphere as hydrogen
sulfide under a variety of situations.
Hydrogen sulfide is a malodorous gas with the characteristic
smell of rotten eggs and is very toxic even at low levels. The odor
of hydrogen sulfide can be detected by most people at concentra-
tions of less than one ppm. Hydrogen sulfide in wastewater can
be a problem from the standpoint of both working conditions
and community relations. It is also a distinct toxicity hazard.
Fatalities from exposure to hydrogen sulfide are reported with
disturbing frequency. In addition to odor and toxicity problems,
hydrogen sulfide is oxidized to sulfuric acid under certain
conditions, and this can lead to corrosion of concrete and metal
structures and equipment.
The chemical reactions between hydrogen peroxide and
hydrogen sulfide are represented in Figure 1. There is an eco-
nomic incentive to use a neutral or slightly acid system for the
conversion of dissolved sulfide to a non-odorous form, elemen-
tal sulfur. Wastewaters that are alkaline shift slowly toward
neutral pH by the action of carbon dioxide, but it may be
profitable to neutralize certain strongly alkaline industrial
wastes before treatment.
H2o2 + H2safcnrSl + 2H20 (I)
4H202+Na2S Na2S04 + 4H20 (II)
Figure I: Reaction of Hydrogen Peroxide and Sulfide.
Although much of the use of hydrogen peroxide for sulfide
odor control is in municipal collection systems and treatment
plants, a number of industrial operations have also found it
useful. The magnitude and type of industrial problems can vary
widely. A spectrum of typical problems and their solutions will
be described to illustrate the variety.
Paper Mill. A paper mill in the northeast produces pa-
perboard using a feed stock primarily of recycled wastepaper.
The system for treating wastewater from the plant operation
handles 2.5 mgd and consists of a primary settling tank, aerated
lagoon, and secondary clarifier (Figure 2). The portion of the
solids from the secondary clarifier that is not recycled goes to the
primary settling tank, is combined with primary solids and
returned to the paper mill for use as a portion of the board
furnish.
Chlorine was being added to the solids system for control of
odors, including hydrogen sulfide. Chlorine usage was 300-400
pounds per day, or approximately 2000 ppm based on solids
weight. A problem of short life cycles for the disc refiner plates
was blamed on corrosion caused by the high chloride content of
the furnish at the refiners. Cost for the monthly change of refiner
plates was estimated at $500. Handling of the ton chlorine
cylinders was also a problem in cost and manpower. A 35-day,
plant-scale trial demonstrated the effectiveness of hydrogen
peroxide in controlling waste treatment odors. Thirty-six (36)
pounds per day of hydrogen peroxide replaced 300 pounds of
chlorine for a net chemical cost savings. It was later established
that the life of the refiner plates was approximately doubled for
an additional saving of about $250.00/month.
-------
120 Hydrogen Peroxide
H&
H2O2
75,000 LB. H2O2/YR.
•Figure 3: Textile Waste Treatment System
-------
Hydrogen Peroxide 121
Overall waste treatment plant performance with the hydrogen
peroxide system is equal or superior to performance with
chlorine treatment. The performance criteria are effluent BOD,
suspended solids and turbidity. The plant now routinely uses
hydrogen peroxide in place of chlorine for odor control.
Textile Plant Waste. A textile dyeing and finishing plant
processing primarily fabrics of synthetic fiber construction had
sulfide odor problems in an equalization tank, a sludge centrif-
uge operation and the wastewater discharged from the plant
(Figure 3).
As in many batch operation systems, it was important to use
an equalization tank to protect the biological portion of the
continuous treatment system from shock variations in waste
composition. However, the average detention time for the 0.8
mgd waste in the equalization tank was nearly a day and the
generated hydrogen sulfide with its odor was displaced into the
atmosphere when the wastewater entered the aerator.
Addition of hydrogen peroxide to the influent of the equaliza-
tion tank controlled this problem. The chemical floe treatment
following the biological treatment was used to remove dyestuff
residues contributing color to the wastewater. The water
discharged from the subsequent biological and chemical treat-
ments developed odors in the sewer downstream of the plant.
Addition of hydrogen peroxide to the wastewater being dis-
charged controlled the odor problem and added DO to the
outfall.
Sludge from the biological and chemical treatments was
dewatered in a centrifuge. Odors that evolved in this operation
were controlled by addition of hydrogen peroxide to the sludge
before the centrifuge. A total of about 75,000 lb/year of
hydrogen peroxide is used for odor control in the waste
treatment operations of this plant.
Pharmaceutical Plant. A large, eastern, manufacturer of
various pharmaceuticals uses an activated sludge treatment
process for approximately 2 mgd of wastewater (Figure 4). After
the wastewater passes through an equalization lagoon, ammo-
nia and phosphoric acid are added as nutrients for the biological
life in the aeration section. Despite the aeration, septic condi-
tions occur in the secondary clarifier with resultant sulfide odors
in both the overflow and in the sludge recycled to the aerator.
Addition of hydrogen peroxide to both of these streams controls
the odors.
The combined sludges from the primary and secondary
clarifiers are treated in an aerobic digestor which discharges to a
sludge thickener. Addition of hydrogen peroxide to the under-
flow of the sludge thickener controls odor at the sludge drying
beds. A total of about 200,000 pounds of hydrogen peroxide is
used annually in this plant.
Soybean Processing. A 0.3 mgd wastewater stream from a
soybean processing operation contains soybean solids and oil as
well as significant sulfate from in-process neutralization of
sodium soaps with sulfuric acid. This waste is fed into a 32,000
gallon holding tank. The settled soybean solids are removed,
and the oil that rises to the surface is decanted. The aqueous
phase has a high BOD of 1000 mg/1 or more. Normal biological
activity depletes the dissolved oxygen in the wastewater and the
high sulfate content encourages generation of hydrogen sulfide
in the holding tank. Later the aqueous layer is discharged and
occasionally additional hydrogen sulfide generation occurs
downstream in the sewer. Initial attempts to control the holding
tank odor problem by aeration, or addition of up to 75 ppm
chlorine to the wastewater, were unsuccessful.
Addition of hydrogen peroxide to the process wastewater
controls the holding tank odor problem. As the wastewater
enters the 32,000-gallon holding tank, hydrogen peroxide is
added at a rate of 40 mg/1. Supplemental hydrogen peroxide is
added to the effluent from the holding tank to control down-
stream odor development.
An ancillary advantage for hydrogen peroxide, when com-
pared with chlorine for controlling odors in the holding tank, is
recovery of soybean solids and oil with no objectionable
chlorinated residues contamination. Hydrogen peroxide con-
Figure 4: Pharmaceutical Waste Treatment System
-------
122 Hydrogen Peroxide
+ M2 pH~4
9
O
M
0
OH
» 0
O"
h2o2
DIABASIC ACIDS
| H202
CO2
Figure 5: Destruction of Phenol with Hydrogen Peroxide
tributes essentially oxygen and water to the system.
Petroleum Refinery. Large amounts of hydrogen sulfide are
frequently encountered in petroleum production and refinery
operations. This hydrogen sulfide is usually stripped from
solution and converted to elemental sulfur by a Claus-type
process. However, there are times when maintenance is required
on sulfide-related parts of the operation, and the choice between
shutting down the sulfide-generating portions of the process or
disposing of the unwanted sulfide by an alternate process is nec-
essary
sary.
In this situation, one large midwestern refinery chooses to add
hydrogen peroxide to the wastewater stream containing the
sulfide for several days. A tank car of hydrogen peroxide is
brought in and the hydrogen peroxide is metered into the stream
as it is by-passed to the balance of the waste treatment process.
When the necessary repairs have been made, the peroxide
addition is discontinued, and the temporary hydrogen peroxide
feed system is stored for the next use cycle.
Food Processing. The food industry removes significant
quantities of dirt during the processing of many agricultural
products. Wastewater containing large amounts of such inert
suspended solids complicates conventional treatment proce-
dures and reuse of the water.
One plant processing an agricultural product approaches this
problem by feeding the wastewater through a primary clarifier
and pumping the muddy underflow water to mud-settling
lagoons. Some of the BOD associated with the muddy water
Table I: Hydrogen Peroxide Oxidation of Pure Phenol Solutions
accompanies the mud as it settles. After a time, anaerobic
biological action begins in the mud, and offensive sulfide odors
are generated. It was found that addition of about 5 mg/1 of
hydrogen peroxide to the settling lagoon influent controlled the
odor problem during the period that the lagoon was filling with
mud. After a lagoon is full of mud, the wastewater isdiverted to
another lagoon, and the full lagoon is allowed to dry. Additional
anaerobic activity proceeds during the initial drying stages with
further release of odor. By covering the lagoon with about a foot
of clean water containing5 to 10 mg/1 of hydrogen peroxide, the
odor problem could be controlled. After two to three weeks, the
anaerobic activity in the mud is exhausted, the layer of water is
drained and the drying proceeds with relatively little odor de-
velopment.
Phenol
Phenols are frequent contaminants in the wastewaters from
chemical and coke operations, petroleum refining and plants
producing and using phenolic resins. Phenols are toxic, degrade
slowly in lakes and streams, and have the property of contribut-
ing extremely disagreeable taste and odor to potable water. This
occurs when the phenols are chlorinated in normal, potable
water purification treatment. Very low limits have been
established by regulatory authorities on the quantities of phenol
that can be discharged to the aquatic environment.
Biological systems are used quite routinely to destroy phenols
in wastewater. This is rather remarkable processing when the
substantial bactericidal properties of phenols are considered.
However, these biological systems are subject to serious
malfunction if care is not exercised in design and operation to
avoid problems such as shock loading and low temperatures.
Hydrogen peroxide destroys phenol quite readily when the
reaction is catalyzed with Fe++salt atapH ofaboutfour(Figure
5). The reaction is a progressive oxidation through ring splitting
to dibasic acids, leading ultimately to carbon dioxide and water.
For most practical purposes, only enough hydrogen peroxide is
used for partial oxidation without complete conversion to
carbon dioxide. The curve in Figure 6 shows the effect of
hydrogen peroxide/ phenol weight ratios on the extent of phenol
destruction. The reaction proceeds rapidly in the 70 to 100° F
temperature range (Table I). Phenol and numerous substituted
phenols respond to this oxidative treatment with hydrogen
peroxide.
Variables such as the amount of hydrogen peroxide and Fe++
catalyst should be investigated to achieve maximum
performance for any specific wastewater. In addition to phenol,
there may be other oxidizable materials that consume hydrogen
peroxide and even less directly related factors must be taken into
account. For example, phosphates will precipitate iron making
Catalyst
Concentration
Temperature
•F
mg/1
;Phe nol
TOC
COD
(theory 1, 190;
None
0.0l%Fe
70
0.0l%Fe
90
0 .01 % F e
120
0 . 0 3 % F e
70
0 .0 3%Fe
90
0.0 3%Fe
120
500
383
1,105
3.4
375
561
5 .0
365
710
9 .0
380
760
2.1
370
7 29
1 .7
355
760
22.0
357
6 20
Initial concentration -- 500 mg/1. 1-° H^/l.O phenol weight ratio. 30-mi n rete ntion
time, initial PH = 5.5. Fe added as ferrous sulfate.
-------
Hydrogen Peroxide 123
150
125
a:
Id
t 100
O*
5
° 7*
2 75
UJ
X
CL
-J
<
I 50
UJ
25
INITIAL PHENOL CONC =
500 Mg/ LITER
I20°F, 30 MINUTES
01% Fe CATALYST
INITIAL pH = 5 5
-fc
0
0 5
30 35
WEIGHT RATIO
Figure 6: The Effect of Hydrogen Peroxide to Phenol Ratio on the Oxidation of Pure Phenol
1.0 15
HYDROGEN
2 0 2 5
PEROXIDE /PHENOL
¦6-
4.0
A 5
it unavailable for the necessary catalytic activity. This hydrogen
peroxide processing for destruction of phenol in wastewater is
used by a sanitizer formulator and the petroleum refining and
chemical industries.
HiOa + sOa-*22—HzSO* «)
Figure 7: Reaction of Hydrogen Peroxide and Sulfur Dioxide
Sulfite
Sulfur dioxide in wastewater adds significant COD, and this
is objectionable in many industrial discharges. Hydrogen
peroxide reacts very rapidly with sulfurous acid (Figure 7). This
reaction is used commercially to destroy traces of sulfur dioxide
in sulfuric acid without introducing any constituent other than a
small amount of water. The same chemistry can be used in a
scrubber system to remove sulfur dioxide from a gas stream10'".
As an example of the destruction of sulfur dioxide in solution,
a southern chemical company had a scrubber discharging a large
flow of water which contained hydrogen chloride and sulfur
dioxide. The sulfur dioxide contributed excessive COD to the
plant wastewater. Addition of chlorine to destroy the sulfur
dioxide was unsuccessful because of poor chlorine solubility in
the strongly acid solution. However, addition of readily soluble
hydrogen peroxide into the sump of the scrubber proceeded
smoothly and corrected the problem. Hydrogen peroxide was
used in essentially stoichiometric quantities. The wastewater
was subsequently blended with other process waste streams to
adjust the pH to an acceptable neutral level before discharge to
the receiving waters.
Thiosulfate
Like many other reduced sulfur compounds, thiosulfate
contributes COD to wastewater streams, and in many cases it
has to be treated before discharge. Chemical, petroleum and
photographic processing operations frequently encounter thio-
sulfates in their wastewater. The reactions of hydrogen peroxide
and thiosulfate are shown in Figure 8.
An example of practical application for this reaction was
found in the overflow of a wastewater collection reservoir from a
steel slag quenching operation in Pennsylvania. The hot steel
slag is sprayed with water for cooling, fracturing and granulat-
ing the product to facilitate subsequent handling and process-
ing. The reservoir was at a low point of the operation and
collected runoff rainwater for much of the water needed for the
quenching. However, during periods of high rainfall, the
capacity of the reservoir was exceeded, and the overflow
discharged into a nearby stream.
Steel slag contains sulfides which leach into the quenching
water, and these sulfides are slowly oxidized in the system. Most
of the reduced sulfur in the reservoir is present as thiosulfate
along with some remaining sulfide. Thus, the COD of the
wastewater is high and with overflow conditions requires
treatment before discharge.
The wastewater discharge was treated by continuous addition
of hydrogen peroxide to the overflow stream at a rate sufficient
to oxidize the thiosulfate to a higher stage of oxidation most
likely, tetrathionate. The wastewater was slightly alkaline to
neutral and the reaction went essentially to completion within
the six hours detention time provided in a concrete basin. The
iodine demand of the basin discharge stream, indicative of
thiosulfate content, was essentially zero and the wastewater
contained significant D.O.
-------
124 Hydrogen Peroxide
H202 + 2S20| + 2H+g§}£Eik-* S40i+2H20
(123
4H202+Na2S205-5H20 + 2Na0H&k*-2Na2S04+l0H20 (2)
Figure 8: Reaction of Hydrogen Peroxide with Thiosulfate
h2o2 + 0C1
¦ Ct + HzO + Oz
(3ZE)
Figure 9: Dechlorination with Hydrogen Peroxide
Dechlorination
Although chlorine is used extensively to destroy pathogenic
organisms in both potable water and discharged wastewater,
there is growing evidence of deleterious effects from this
treatment. The effects are seen on the nearby aquatic environ-
ment and possibly longer range on ultimate reconsumers of the
water —you and me.
In an effort to combat these effects on the aquatic life in the
receiving waters, limitations are placed on the amount of active
chlorine that can be discharged. In many instances, this requires
dechlorination of the wastewater. Hydrogen peroxide readily
reacts with free available chlorine according to equation VI
(Figure 9). It should be pointed out that conversely, the reaction
between hydrogen peroxide and combined available chlorine
(chloramine) is very sluggish. Most of the available chlorine in
the discharge of municipal treatment plants is present as
combined available chlorine. On the other hand, chlorine-
caustic plants and chemical plants frequently discharge low lev-
els of free available chlorine.
The FMC Corporation has a chlorine-caustic plant at
Squamish, British Columbia. Because of the pristine character
of the receiving waters in the area, the discharge of available
chlorine is very severely restricted. Since 1971, addition of about
0.6 mg/1 of hydrogen peroxide to the 7 mgd wastewater stream
has prevented the discharge of measurable amounts of either
available chlorine or sulfide.
Zinc Recovery
Not all waste treatment represents expense without return. As
an example of recovery of a valuable product from waste, zinc
values are being recovered from a waste sludge which has been
collected for thirty years. During the manufacture of rayon, zinc
sulfate is present in the cellulose regeneration baths and
functions primarily as a delustering agent. In the earlier part of
this century, the zinc values in the sludge from this operation did
not justify recovery, and the sludge has been accumulated in
large lagoons. Metals, including zinc, have increased sharply in
value in more recent years and recovery of zinc as now
practiced12 effects economies, conservation and environmental
protection.
In this process, outlined schematically in Figure 10, the sludge
containing zinc as the hydroxide is acidified with sulfuric acid to
form zinc sulfate. The insoluble materials are removed from the
solution of zinc sulfate by filtration. The filtrate contains soluble
iron salts as impurities along with the desired zinc sulfate. The
pH of the filtrate is raised to about 4.5, and hydrogen peroxide is
added to oxidize the soluble ferrous iron to insoluble ferric
oxides. The hydrated iron oxides are then removed by filtration,
and the now "pure" zinc sulfate solution is recycled to the rayon
process.
SUMMARY
As is evident in these examples, hydrogen peroxide is finding
increasing and diverse use in industrial wastewater pollution
control. It deserves evaluation whenever sulfide odors or other
sulfur compounds such as mercaptans, thiosulfate and sulfur
dioxide are involved. Phenol and free available chlorine can also
be destroyed with hydrogen peroxide. In secondary biological
treatment systems, hydrogen peroxide can be a source of
supplemental oxygen, a control agent for filamentous sludge
bulking or a preventative for rising sludge resulting from
denitrification.
Treatments with hydrogen peroxide are not magic cure-alls.
After a careful appraisal of problem conditions, the intelligent
application of hydrogen peroxide can very often effect an
improvement or complete elimination of the problem. The
ure 10: Recovery of Zinc Values
-------
Hydrogen Peroxide 125
hydrogen peroxide manufacturers have the expertise and will
help in any reasonable way to develop a sound economical
peroxide treatment for your needs.
REFERENCES
1. Shepherd, J. and Hobbs, M. (FMC Corporation) U.S.
Patent 3,705,098 (1972), "Sewage Treatment with Hydro-
gen Peroxide."
2. Freidman, L. (FMC Corporation) U.S. Patent 3,530,067
(1970), "Method of Treating Sewage."
3. Cole, C. Stanberg and Bishop D„ 5th Mid-Atlantic
Industrial Waste Conference, Philadelphia, Pennsylvania,
November 1971, "Hydrogen Peroxide Controls Filament-
ous Bulking in Activated Sludge."
4. Caropreso, F., Raleigh, C. and Brown, J., Industrial Waste
27, November and December 1974, "Hydrogen Peroxide
Controls Bulking."
5. Eisenhauer, H., Journal WPCF, September 1974, pages
1116-1128, "Oxidation of Phenolic Wastes with Hydrogen
Peroxide and a Ferrous Salt Reagent."
6. The Oil and Gas Journal; January 20, 1975, pages 84-86,
"Phenols in Refinery Wastewater Can be Oxidized with
Hydrogen Peroxide."
7. Cole, C., Ochs, L. and Funnell, F., 46th Annual Water
Pollution Control Federation Conference. October 1973,
"Hydrogen Peroxide Solves Need for Supplemental Oxy-
gen Sources in Waste Treatment."
8. Macenieks, P. and Raleigh, C., 7th Middle Atlantic
Industrial Waste Conference, Drexel University,
November 1974, "The Use of Hydrogen Peroxide for the
Oxidation of Sulfur Chemical Wastes."
9. Kelsey, R., Technical Engineering, February 1974, pages
37-40, "Aseptic-Packaging-Machine Design."
10. Hammond, M. (DuPont) U.S. Patent 3,760,061 (1973)
"High Strength Acid Containing Hydrogen Peroxide to
Scrub Sulfur Dioxide."
11. Wood, C. British Patent 930,584 (1963) "Improvements in
and Relating to the Treatment of Waste Gases."
12. Business Week, April 28, 1975, page 32.
-------
Impacts of the Disposal
of Heavy Metals
in Residues on Land
and Crops*
J. F. Parr, E. Epstein,
R. L. Chaney, and G. B. Willson
Agricultural Research Service
U.S. Department of Agriculture
Beltsville, Maryland
INTRODUCTION
One of the most urgent problems confronting many munici-
palities in the United States today is that of disposing of their
sewage sludges in a manner that is environmentally acceptable,
economically feasible, and not hazardous to human health.
During the past decade legislative actions have imposed strict
limitations on the disposal of sewage sludge by incineration (Air
Quality Act of 1967), fresh water dilution (Water Pollution
Control Act Amendments of 1972), and ocean dumping
(Marine Protection, Research, and Sanctuaries Act of 1972).
The U.S. Environmental Protection Agency has ordered munic-
ipalities in coastal areas to cease ocean dumping of sewage
sludge by 1981. The situation will become even more critical
because the costs of present methods of'sludge disposal (e.g.,
trenching, landfilling, and incineration) are increasing rapidly,
and could reach prohibitive levels in the near future*. Moreover,
the development and implementation of improved wastewater
treatment is expected to increase the present annual U.S. sludge
production of about 5 million dry tons to more than 10 million
tons by 1985. Consequently, many municipalities are now con-
sidering land application methods for the disposal and/or
utilization of their sewage sludges. According to Farrell13
approximately 20 percent of municipal wastewater sludges in
the U.S. are currently spread on land. It is likely that this figure
will increase significantly during the next decade.
Chemical Composition of Sewage Sludges
Sewage sludge by definition is the solids removed from a
wastewater stream in the process of capturing pollutants so that
their re-entry into the environment may be managed to minim-
ize undesirable effects. Primary treatment (e.g. sedimentation)
produces undigested or raw primary sludge, while secondary
treatment such as waste activation produces waste activated
sludge. Mixed primary and secondary sludges are often anae-
robically digested. Advanced wastewater treatment methods
produce AWT sludges with a comparatively higher content of
chemicals added to remove nutrients from the effluent.
Sewage sludge is potentially a valuable resource which
consists of 40 to 60 percent organic matter, and contains both
macronutrients (e.g. nitrogen, phosphorus, and calcium) and
micronutrients (e.g. zinc, copper, and manganese) essential for
plant growth. Sludge can also be beneficial as an organic
amendment for improving the physical properties of marginal
soils10-11. The application rate on agricultural land will be limit-
by the level of contamination from heavy metals, toxic
lie chemicals, and pathogens. Table 1 shows the extent to
' h the chemical composition of different sewage sludges can
7. The composition varies in accordance with the method of
astewater treatment, and the type and amount of industrial
astc effluents that are discharged into the sanitary sewers.
rable I: Total Elemental Composition of Sewage Sludges from
a Number of Municipalities in the United States*17
Component
Minimum
2 /
Concentrat ion-
Maximum
Median
—
Organic C
6.5
48.0
30.4
Inorganic C
0. 3
54. 3
1.4
Total N
•0.1
17.6
3.3
NHt-N
4
¦0.1
6.7
1.0
N0~-N
•'0. 1
0. 5
<0.1
Total P
<0. 1
14.3
2.3
Inorganic P
<0. 1
2.4
1.6
Total S
0.6
1. 5
1.1
Ca
0.10
25.0
3.9
Fe
<0. 10
15.3
1.1
A1
0.10
13.5
0.4
Na
0.01
3.1
0.2
K
0.02
2.6
0.3
Mg
0.03
2.0
0.4
Zn
101
27800
1740
Cu
84
10400
850
Ni
2
3515
82
Cr
10
99000
890
Mn
18
7100
260
Cd
3
3410
16
Pb
13
19730
500
Hg
< i_
10600
5
Co
1
18
4
Mo
5
39
30
Ba
21
8980
162
As
6
230
10
B
4
757
33
* Data compiled from over 200 samples from eight states.
t Values expressed on 110°C weight basis.
~Some of the research reported herein was partially supported by
unds from the Maryland Environmental Service, Annapolis, Maryland
ind the U.S. Environmental Protection Agency, Office of Research and
Development, Cincinnati, Ohio.
-------
Impacts Heavy Metals—127
Problems Associated with Land Application of
Sewage Sludges
Sewage sludges can be applied to land as liquids (2 to 10%
solids), as partially dewatercd materials (18 to 25% solids), or as
heat-dried and air-dried products (90 to 99%, solids). There are,
however, a number of problems that must be considered when
these materials are applied to land:
(a) Odors can be a major problem in land application of
sludges. Avoidance of odors requires immediate incorpo-
ration of sludge into the soil. Sites for sludge spreading
must be selected with respect to population density, air
drainage, and the prevailing wind direction.
(b) The effect of land application of sludge on human health
is a matter of concern. Sewage sludges contain human
pathogens some of which may survive in soil for only a
few days, while others may survive for 6 months or more4.
The eggs of intestinal worms such as Asi ans lumbricoides
can survive for a number of years. Health risks would be
considerably greater with raw or undigested sludge as
compared with digested sludges.
(c) Specialized equipment is often required to apply and
incorporate sludges on land. Partially dewatered sludges
are difficult to spread at a uniform rate of application.
(d) Lack of public acceptance can be a problem. Residents
along hauling routes as well as those living close to the
application site often object to the use of sludge on land.
(e) Improper site management can cause excessive runoff
containing sludge, nitrate pollution of groundwater or
surface waters, odors, and other environmental prob-
lems.
(0 In some regions, sludge application may have to be
curtailed during winter months. A number of states
prohibit the application of sludge to frozen ground, thus
necessitating costly storage facilities. Storage of sludge
can result in anaerobic decomposition and the produc-
tion of odors.
(g) The high cost of land for sludge spreading projects near
urban areas may be a constraint on this method of
disposal.
(h) Excessive amounts of heavy metals and industrial organic
chemicals in sludges applied to land can be a major
problem because of phytotoxic effects, and because some
metals and chemicals may be absorbed by crops and
endanger human health by entering the food chain. This
subject will be discussed below in greater detail.
Composting of Sewage Sludge for Utilization as a
Fertilizer and Soil Conditioner
In view of these problems, and particularly those of public
concern about odors and pathogens, along with a growing
consensus that good quality sludges should be recycled benefi-
cially on land, there is increasing interest in the U.S. in
composting as a means of stabilizing sludge for land application.
Most of the problems with land application of sewage sludges
can be resolved by composting.
The Beltsville Aerated Pile Method for Composting
Sewage Sludge
Since 1973, the Biological Waste Management and Soil Ni-
trogen Laboratory at USDA's National Agricultural Research
Center near Beltsville, Maryland, has been conducting research
on the composting of sewage sludges for use as a fertilizer and
soil conditioner. The laboratory has developed a process for
composting either undigested (raw) or digested sludges''
In this process, raw or digested sludges (18 to 25% solids) are
mixed with woodchips or other bulking materials (e.g. leaves,
refuse, paper, peanut hulls, corn cobs, or wood bark) and
composted in a stationary aerated pile for a period of 3 weeks. A
three-dimensional schematic diagram of the aerated pile method
is shown in Figure 1. Mixing the sludge with a bulking material
is essential to provide the necessary structure and porosity to
COMPOSTING
WITH FORCED AERATION
Figure I: Three-Dimensional Schematic Diagram of the Beltsville Aerated Pile Method for Composting Sewage Sludges.
-------
128 Impacts—Heavy Metals
accommodate forced aeration, and to lower the moisture
content of the biomass, thereby ensuring a rapid aerobic
composting process. Aerobic conditions are maintained by
drawing air through the pile with a blower connected to a loop of
perforated pipe in the base. The effluent air stream is conducted
into a small pile of screened cured com post, where odorous
gases are effectively removed. During the composting period the
pile is blanketed with a 12- to 18-inch layer of compost for
insulation and odor control. After composting, the pile is taken
down, mixed thoroughly, and placed in a curing pile for 4 weeks.
The woodchips and compost are then separated by screening
and the woodchips recycled with new sludge. The compost is
then ready for use.
Composition of Sewage Sludges and Their Composts
Composition of raw and digested sludges from the Washing-
ton, D.C., Blue Plains Wastewater Treatment Plant, and their
respective composts processed at the USDA Composting
Facility at Beltsville, Maryland, is shown in Table II. The low
heavy metal content of these sludges makes them quite accept-
able for composting and utilization on agricultural lands.
Digested sludges are typically higher in heavy metals than the
raw or undigested sludges from which they are dgrived, because
metals are concentrated during anaerobic digestion. The com-
posts have a lower heavy metal content than their parent sludges
because of a dilution effect from the woodchips. The level of
chlorinated hydrocarbon pesticides in most U.S. domestic
sludges is now quite low since these chemicals are no longer
used. Less persistent pesticides such as organophosphates and
carbamates would degrade rapidly in sewage sludge. The
presence of industrial chemicals such as polychlorinated biphen-
yls (PCB'S) in sludges being returned to land is of concern
because of possible adverse effects on the food chain.
Relative Effects of Treatment Processes on Destruction
of Pathogens and Sludge Stabilization
The relative effects of different wastewater treatment pro-
cesses on the destruction of pathogens and stabilization of
sludges were compared1-1 and are reported in Table 111. Pasteuri-
zation, ionizing radiation, and heat treatment are capable of
completely eliminating pathogens; however, the sludges are left
in an unstabilized condition and will undergo putrefaction with
aoic iui tumpuov.uj,
^ 1^ gihHom from the Washington, D.C., Blue Plains Wastewater Treatment Plant and
Component
Raw
sludge
Raw sludge
compost
Digested
sludge
Digested sludge
compost
PH
Water, %
Organic carbon,
Total N, %
NH^ -N, ppm
P, %
K, %
Ca, %
Zn, ppm
Cu, ppm
Cd, ppm
Ni, ppm
Pb, ppm
PCBs^,
2/
BHC— , ppm
3/
DDE- , ppm
DDT, ppm
%
9.5
78
31
3.8
1540
1.5
0.2
1.4
980
420
10
85
425
0.24
1.22
0.01
0.06
6.8
35
23
1.6
235
1.0
0.2
1.4
770
300
8
55
290
0.17
0.10
<0.01
0.02
6.5
76
24
2.3
1210
2.2
0.2
2.0
1760
725
19
575
0.24
0.13
6.8
35
13
0.9
190
1.0
0.1
2.0
1000
250
9
320
0.25
0.05
0.008
0.06
1/ Polychlorinated biphenyls as Arochlor 1254.
2_/ The gamma isomer of benzene hexachloride is also called lindane.
3/ DDE results from the dehydrochlorination of DDT.
-------
Impacts— Heavy Metals 129
the production of malodors when reinoculated and/or applied
to land. Anaerobic and aerobic digestion effectively stabilize
sludge, but destruction of pathogens is rated only fair. Lime
treatment and chlorination of sludge provide good pathogen
control, but stabilization is incomplete. Composting of sewage
sludges, through the activity of thermophilic and thermotoler-
ant microorganisms, is the only process that provides acceptable
pathogen reduction and effective stabilization.
The Beltsville Method of composting has proven to be
effective in destroying primary human pathogens found in
sewage sludges including (a) helminthic ova (eggs of intestinal
worms), (b) salmonella bacteria, and (c) viruses4'9. High
temperatures generated through the activity of thermophilic
microorganisms are responsible for effective destruction of
pathogens. Temperatures in the pile increase rapidly into the
thermophilic range within the first 3 days after composting
begins, and usually remain between 65°C (149°F) and 75°C
(167°F) for several weeks. Temperatures above 55°C (131°F)
for several days will effectively destroy most pathogens.
Advantages of Composting Sewage Sludge for Land
Application.
There are a number of advantages of composting sewage
sludge for land application:
(a) Stabilization of raw sludge by composting would elimi-
nate the need for costly anaerobic digestion, or other
means of stabilization.
(b) Microbial decomposition of the volatile organic fraction
during composting eliminates malodors and produces a
stable, humus-like, organic material.
(c) Heat produced during composting effectively destroys
human pathogens.
(d) Compost can be conveniently stored, and easily and
uniformly spread on land without expensive equipment.
(e) Compost is a valuable product that can be applied to land
as a source of nutrients for plants, and as an organic
amendment to improve the physical properties of soils
(i.e. a soil conditioner).
Impacts of Sludge-Borne Heavy Metals on Land
and Crops
Some sewage sludges contain sufficiently large amounts of
heavy metals to make them unsuitable for either direct applica-
tion to land or composting. Excessive amounts of these metals
are often found where industrial effluent is discharged into the
sanitary sewers without pretreatment (Table I). Thus, the
uncontrolled application of high metal sludges on land can
result in soil enrichment of heavy metals. Potential problems
from heavy metals in municipal sludges are discussed in recent
reviews5'6'7. Experiments have shown that soil enrichment by
zinc (Zn), copper (Cu), and nickel (Ni) can cuase direct
phytotoxic effects manifested in repressed growth and yield.
Heavy metals may also accumulate in plant tissues and thus
enter the food chain.
Cadmium: Sources and Effects on Human Health
The element of greatest concern to human health where
sewage sludges and sludge composts are applied to land is
cadmium (Cd), since it is readily absorbed by most crops and is
not generally phytotoxic at the concentrations normally
encountered. Therefore, Cd can accumulate in plants and enter
the food chain more readily than lead (Pb) or mercury (Hg),
which are not absorbed by crops to any great extent. Most
human exposure to Cd comes from food (principally grain prod-
ucts, vegetables, and fruits) and tobacco, and results in an
accumulation of Cd in the liver and kidney. Approximately 3 to
5 percent of dietary Cd is retained by these organs. Absorbed Cd
Table III: Relative Effects of Various Wastewater Treatment
Processes on Destruction of Pathogens and Stabilization of
Sewage Sludges
Processes
Pathogen
Reduction
Putrefaction
Potential
Odor
Abatement
Anaerobic digestion
Fair
Low
Good
Aerobic digestion
Fair
Low
Good
Chlorination, heavy
Good
Medium
Good
Lime treatment
Good
Medium
Good
Pasteurization (70°C)
Excellent
High
Poor
Ionizing radiation
Excellent
High
Fair
Heat treatment (195°C)
Excellent
High
Poor
Composting (60 C)
Good
Low
Good
Long-term lagooning of
digested sludge
Good
-
--
Table IV: "Typical" U.S. Daily Intake and Retention of
Cadmium from Various Sources.
Source
Concentration
Intake
Retained^
ug
Pg
Total diet
0.04 ppm
51
2.30
Drinking water
0.0014 ppm
2.8
0.13
Air
0.006 ug/m^
0.12
0.005
Cigarettes (20)
1.0 ppm
3.1
1.4
1/ Assuming 4.5%
of ingested Cd and 45% of inhaled
Cd are
retained.
is excreted very slowly and can accumulate to levels which might
cause kidney failure. Among the sources that contribute to the
level of Cd in food are (a) soils and surface waters contaminated
by disposal of wastes, (b) soils that are inherently high in Cd
because of geochemical factors, (c) food processing, (d) indus-
trial fallout, and (e) the use of phospate fertilizers containing Cd.
Domestic animals may also ingest Cd in their rations; however,
most of it is retained in the liver and kidney, with very little being
found in either the meat or milk.
Tobacco is a Cd accumulator plant and can contain from 1 to
6 ppm of Cd by weight, even where sludges have never been ap-
plied. The source of this Cd is essentially from phosphatic
fertilizers. Moreover, tobacco is usually grown under acid soil
conditions which enhance the availability of Cd for plant
uptake. When smokers inhale, about 30 percent of the Cd is
absorbed by the lung. Thus, an individual who smokes one pack
of cigarettes per day could actually double his body burden of
absorbed Cd15.
Table IV shows the "typical" U.S. daily Cd intake and
retention based on a number of literature reports. While less
than 5 percent of dietary Cd is retained, the amount of Cd
retained from tobacco can approach 50 percent. The World
Health Organization (WHO) has established that the maximum
permissible level of dietary Cd should not exceed 70 p g/ per-
son/day. The U.S. Food and Drug Administration (FDA)
calculates that U.S. citizens ingest from 70 to 90 percent of this
level, and that any further increase in our dietary intake of this
element should be limited wherever possible.3. Thus, the effect
of land utilization of organic wastes, as fertilizers and soil
conditioners, on the levels of Cd in food chain crops could
ultimately impose constraints on this practice.
Factors Affecting the Plant Availability, Uptake, and
Phytotoxicity of Heavy Metals
The availability and phytotoxicity of heavy metals to plants,
-------
130 Impacts Heavy Metals
their uptake, and accumulation depend on a number of soil,
plant, and metal factors listed in Table V. For example, toxic
metals arc more available to plants when the soil pH is below
6.5. Thus, the practice of liming soils to a pH of 6.0 to 6.5 is rec-
ommended to suppress the availability and toxicity of heavy
metals to plants. Soil organic matter can chelate or bind metal
cations, making them less available to plants. The application of
organic amendments such as manures and composts can also
lower the availability of heavy metals through chelation and the
formation of complex ions. Soil phosphorus can interact with
certain metals thereby reducing their availability to plants.
The cation exchange capacity (CEC), an expression ofa soil's
capacity to retain metal cations, is important in binding heavy
metals, thus decreasing their availability to plants. Generally,
the higher the clay and organic matter content of soils, the
higher their CEC value. Heavy metals are relatively less
available to plants in high CEC soils (sands or sandy loams).
Soil moisture, temperature, and aeration are factors which
interact to affect plant growth, uptake, and accumulation of
metals. Increasing the soil temperature, for example, can
increase plant growth, and the availability and uptake of heavy
metals as well.
basis, heavy metals are less available to plants in soil amended
with composted sewage sludges than with uncomposted raw and
digested sludges*. The reason for this is not known but is the
subject of continuing research.
Plant species, and even plant varieties, vary widely in their
sensitivity to heavy metals. For example, some vegetable crops
are very susceptible to injury by heavy metals; corn, soybeans,
and cereal grains are only moderately susceptible, while forage
grasses are relatively tolerant. Generally, the older leaves of
most plants will contain higher amounts of heavy metals than
the younger tissues. Moreover, the grain and fruit accumulate
lower amounts of heavy metals than the leafy tissues. This
observation is reported in Table VI, which shows the effect of
sludge application rates on the Zn and Cd content of corn grain
and leaves. As the sludge rate increased, both the Zn and Cd
concentrations increased in the plant tissues. However, lower
Table V: Major Factors Affecting Heavy Metal Uptake and
Accumulation by Plants.
Soi 1_ Factors
1. Soil pH - Toxic metals are more available to plants below pH 6.5.
2. Organic" mactwr - Organic matter ran chelate and complex heavy metals
so that they are less available to plants.
3. Soil phosphorus - Phosphorus Interacts with certain metal cations to
reduce their aval lability to plants.
4. Cation Exchange Capacity (CEC) - Important in binding of metal
cations - Soils with a high CEC are safer for disposal of sludges.
5. Moisture, temperature, and aeration - These car affect plant growth
and uptake of metals.
PIant Factors
1. Plant species and varieties - Vegetable crops are more sensitive to
heavy metals than grasses.
2. Organs of the plant - Grain and fruit accumulate lower amounts of
heavy Petals than leafy tissues.
3. Plant age and seasonal effects - The older leaves of plants will
contain higher amounts of metals.
Metal Factors
1. Reversion - With time, metals may revert to unavailable foras in soil
. Metals - Zn, Cu, Ni and other metal* differ In their relative
toxicities to plants and in their reactivity In soils.
Table VI: Uptake of Zinc and Cadmium by Corn Grown on a
Keyport Silt Loam Soil Amended with Increasing Rates of
Digested Sewage Sludge
S ! .1|>P 1 i''
/ 1 /
Ions/, lire
0
1 7. r)
15
70
1 (Vi
ppm
>7
'.I
I HO
K.H
ppm
0.04
0.11
0.?1
0.1/
().,»0
ppm
0.41
1 .11
1 . 74
1 .89
1 .69
1/ App 1 i <:
amounts accumulated in the grain than in the leaves. Similar
results are illustrated in Figure 2 which shows considerably
higher levels of Cd in the foliar portions of many crops than in
the grain, fruit, or edible roots.
Heavy metals differ notably in their relative toxicities to
plants and in their reactivity in soils. For example, on an
equivalent basis Cu is generally more phytotoxic than Zn, while
Ni is considerably more phytotoxic than either Zn or Cu. For
reasons as yet unexplained, heavy metals can revert with time in
soil to forms unavailable to plants.
Thus, in the development of environmentally acceptable
methods for the utilization of sewage sludge and sludge
composts on land, researchers are concerned with interactions
of plants, soils, and heavy metals and their effect on plant
availability, uptake, accumulation, phototoxicity, and move-
ment in soil. This ultimate objective is to develop soil manage-
ment systems which can utilize organic wastes as resources while
minimizing any potentially hazardous effects of heavy metals on
soil fertility, food quality, and human health.
paddy i ice
upland rice
Bsudangrass
w. clover
o 11 a I f a
bermudagrasst
field bean
wheat
zucchini squash
soybean
D tall fescue
corn
] carrot
Bingham, ej al., 1975, 1976.
Domino silt loam, pH 7 5
10 ppm Cd added
(Denotes groin, fruit, or edible root
2q 40 60 80 )00 ) 20 140 160
Cadmium in plant tissue, ppm dry weight
180
R. L. Chaney and E. Epstein, unpublished data.
Figure 2: Crop differences in the uptake and accumulation of
Cd. Crops were grown on calcareous Domino silt loam
amended with a Cd-enriched sewage sludge to a level of 10 ppm
Cd. Foliar Cd is denoted by the open bars, and non-foliar (grain,
fruit, or edible root) Cd by the black bars.2
Use of the Cd:Zn Ratio to Define Acceptable Sludges for
Land Application
The metal contents of digested sewage sludges based on the
maximum concentrations observed, the maximum domestic
level acceptable for landspreading or composting, and the
attainable low levels which could be achieved through pretreat-
-------
Impacts Heavy Metals 131
ment and abatement procedures, are presented in Table VII6.
The authors feel that the Cd Zn ratio should not exceed 0.010,
that is, that the Cd content of sewage sludge should not exceed 1
percent of the zinc content. The reasons for this, according to
Chancy and Giordano6 are that (a) Zn will accumulate to
phytotoxic levels before sufficient Cd can be absorbed to
endanger the food chain, (b)Zn inhibits Cd uptake by dicotyled-
enous plants at low Cd/Zn ratios, and (c) Zn alleviates injury
from excessive levels of Cd in animals. With abatement of metal-
containing industrial effluents and/or pretreatment of the
effluents to remove the metals before discharging into sanitary
sewers, it should be possible for most U.S. sludges to reach the
low levels shown in Table VII.
Table VII: Metal Contents of Digested Sewage Sludges (Dry
Weight Basis)6.
Table VIII: Recommended Maximum Cumulative Sludge
Metal Applications for Privately-owned Cropland.2'2'-''4.
Metal
Attainable Maximum
, , ,1/ . 2/
low level-- domes tiir-
Observed
max imum
Zn, ppm
750 2,500
50,000
Cu, ppm
250 1,000
17,000
Ni, ppm
25 200
8,000
Cd, ppm
5.0 25
3,400
Cd/Zn, X
0.8 1.0
110
Pb, ppm
1,000
10,000
Hg, ppm
2.0 10
100
Cr, ppm
50 1,000
30,000
!/ Observed
in sludges generated from wastewater of
newer suburban
communit J
es with no industrial effluent. Sources
of these metals
are assumed to be from deterioration of domestic
piumb ing
fIxt ures
2/ Typical <
and storm sewers.
f sludges from communities without excessive industrial waste
sources or with adequate source abatement. Sludges which exceed any
of these
metal concentrations are not recommendet
for landspreading
or composting.
USD A Guidelines to Limit Heavy Metal Loadings
on Agricultural Land
To limit the build-up of heavy metals on agricultural land
resulting from the landspreading of either sewage sludges or
sludge composts, USDA proposed certain guidelines in 1976*.
Hopefully, such guidelines will encourage the use of good
quality sludges (low heavy metal content) while limiting the use
of bad sludges (high heavy metal content) for land application.
The guidelines are based on the best available information from
scientists at a number of state universities and agricultural
experiment stations, as well as USDA. Two categories of land
were delineated: (1) privately owned land and (2) land dedicated
to sludge application, i.e., publicly owned or leased land.
Table VIII shows the maximum allowable cumulative sludge
metal loadings for privately owned land according to the soil
cation exchange capacity. Soils in the 0 to 5 CEC range would be
characterized by sands and sandy loams; the 5 to 15 range by silt
loams; and >15 by silty clay loams and clays. Thus, higher
metal loadings would be allowable on heavier textured soils.
Sludges having Cd contents greater than 25 mg/kg (ppm)
should not be applied to privately owned land if their Cd/Zn
ratios exceed 1.0 percent. Sludges having a Cd content of up to
1.5 percent of their Zn content could be applied to land on a lim-
ited basis provided there is an ongoing abatement program to
reduce the Cd to an acceptable level (i.e., Cd:Zn = 1.0%). If the
Cd content of sludge exceeds 25 ppm, it is likely that the Cd is
coming from an abatable source. Cadmium loadings on land
should not exceed I kg/ha/year for liquid sludge and not more
than 2 kg/ha/year for dewatered sludge or composted sludge.
When sludges are applied, the soil should be limed to pH 6.5 and
* Copies of the draft document are available from the Office of
Environmental Quality Activities, Office or the Secretary, USDA,
Washington, D.C.
Soil Cation Exchange Capacity (meq/lOOg)--'
0-5 5-15 >15
maximum addition, kg/ha
250
500
1000
125
250
500
50
100
200
5
10
20
500
1000
2000
)/ Annual Cd application should not exceed 2 kg/ha from dewatered or
composted sludges, or 1 kg/ha from liquid sludge; sludge application
should not supply more crop available N than the crop requires.
2/ Sludges having Cd greater than 25 ppm should not be applied unless
the Cd/Zn <_ 0.015. If sludge Cd/Zn exceeds 0.015, an abatement
program to reduce sludge Cd to an acceptable level should be
in it iated.'
3/ These recommendations apply only to soils that are adjusted to > pH
6.5 when sludge is applied, and are to be managed to pH > 6.2 there-
a f ter.
4/ Leafy vegetables or tobacco should not be grown on sludge-treated
cropland.
5/ The CEC designation is for unamended soils.
Table IX: Effect of the Metal Content of Sewage Sludges from
Four Municipalities on the Maximum Allowable Cumulative
Amount of Dry Material that Can Be Applied to Land as
Nitrogen Fertilizer According to the USDA Guidelines.
Metal and
cumulative amount
Zn, ppm
ppm
Ni, ppm
Cd, ppm
Cd/Zn, %
Piscataway Blue Plains
altimore Grand Rapids
l.evel in sludge
T/A
Mt/ha-
Fertilizer, Yr
1/
540
240
33
5
0.9
413
926
370
1780
486
42
15
0.8
5100
1760
280
21
0.4
Cumulative amount
125 44
281 98
112 40
20500
3140
7850
165
0.8
5.7
12.7
3
1/ This assumes a soil CEC of 5 to 15 meq/100 g, and limits the cumulative
Zn to 500 kg/ha (see Table 8).
2/ Based on a sludge N application rate of 100 kg N/ha/year and sludge N
content of 4.0%.
thereafter maintained in the range of 6.0 to 6.5.
On publicly controlled land, up to 5 times the amounts of
sludge-borne metals listed in Table VIII may be applied if the
sludge is incorporated into soil to a depth of 15 cm. Where
deeper incorporation is practiced, proportionally higher total
metal applications may be made. These metal loadings are
permissible only when solids are limed and maintained at a pH
2? 6.5.
Annual rates of application of sludge or sludge compost
should be based on the nitrogen or phosphorus requirements of
crops. Table IX illustrates the effect of the metal content of four
sewage sludges on the maximum amounts of sludge (dry weight
basis) that can be applied at N fertilizer rates according to the
USDA Guidelines. For example, assuming (a) a soil CEC of 5 to
15 meq/100 g, (b) cumulative Zn loading limited to 500 kg/ha,
(c) a sludge N content of 4 percent, and (d) a sludge application
rate equivalent to 100 kg of N/ hectare/ year, sewage sludge from
the Piscataway wastewater treatment plant in Prince Georges
County, Maryland (Washington Suburban Sanitary Commis-
-------
132 Impacts-Heavy Metals
sion) could be applied for 370 years. Because of their progres-
sively higher Zn contents, sludges from the Blue Plains Waste-
water Treatment Plant (Washington, D.C.) Baltimore,
Maryland, and Grand Rapids, Michigan could be applied for
112, 40, and only 3 years, respectively.
The Piscataway and Blue Plains sludges are good quality
sludges for land application, either directly, or after composting.
With some abatement ofZn, Cu, and Ni, the Baltimore sludge
would be quite suitable for land application. The Grand Rapids
sludge should not be applied on land until the content of all four
metals (Zn, Cu, Ni, and Cd) reaches a suitably low level (Table
VIII). Interestingly, the Cd:Zn ratio of Grand Rapids sludge is
less than 1 percent, mainly because of its extremely high Zn
content.
SUMMARY AND CONCLUSIONS
Recent legislative actions have imposed strict limitations on
the disposal of sewage sludges by incineration, fresh water
dilution, and ocean dumping. Consequently, many municipali-
ties are now considering land application methods for disposal
and/or utilization of their sludges.
The application of sewage sludges on land has raised certain
questions concerning possible adverse affects on human health.
Some sludges may contain large amounts of heavy metals,
making them unsuitable for application to land. Heavy metals
can accumulate in plant tissues and enter the food chain through
direct ingestion by humans, or indirectly through animals. Some
sludges may also contain certain organic chemicals of industrial
origin that might cause adverse effects on human health by
contamination of surface waters. Sewage sludges may contain
organisms that are pathogenic to humans. These organisms can
survive on plants for days or even weeks, and in soils for much
longer periods.
An aerated pile method has recently been developed by the
U.S. Department of Agriculture at Beltsville, Maryland for the
composting of both raw and digested sewage sludges. This
method transforms sludge into compost in about 3 weeks,
during which time odors are abated and pathogenic organisms
are destroyed. The finished compost is humus-like material, free
of malodors, and useful as both a low-analysis fertilizer and a
soil conditioner. Unlike sludges, it is conveniently stored, is
easily handled, and can be uniformly spread on land.
Research at Beltsville on phytotoxicity and plant uptake of
sludge-borne metals suggests that management systems can be
developed to utilize composted sludges as nutrient and organic
resources for agricultural lands, while minimizing any poten-
tially hazardous effects on soil fertility, food quality, and human
health. In 1976, the U.S. Department of Agriculture proposed
certain guidelines to limit heavy metal loadings on agricultural
land from the application of sewage sludges or sludge composts.
These guidelines are intended to encourage the use of good
quality sludges on land, and to limit the use of sludges
containing excessive amounts of heavy metals. Where industries
are discharging effluents containing heavy metals and toxic
organic chemicals into sanitary sewers, abatement and/or
pretreatment procedures should be used to ensure good quality
sludges for composting and recycling on land.
Sewage sludge composts can markedly improve soil physical
properties, as evidenced by increased water content, increased
water retention, increased aeration and permeability, lower bulk
density, decreased surface crusting, increased water infiltration,
decreased runoff, and increased rooting depth. In addition to
their use in agriculture, sludge composts can be used advanta-
geously as a topsoil substitute for land reclamation and public
works projects, for production of turfgrasses, for nursery pro-
duction of trees and ornamental plants, on golf courses and
cemeteries, for revegetation of disturbed lands (e.g., from
surface mining), and for landscaping the grounds of parks and
public buildings.
references
1. Bingham, F. T„ A. L. Page, R. J. Mahler,andT. J. Ganje.
1975. Growth and cadmium accumulation of plants grown
on a soil treated with a cadmium-enriched sewage sludge. J.
Environ. Qual. 4:207-211.
2. Bingham, F. T., A. L. Page, R.J. Mahler, and T. J. Ganje.
1976. Yield and cadmium accumulation of forage species in
relation to cadmium content of sludge-amended soil. J.
Environ. Qual. 5:57-60.
3 Braude, G. L., C. F. Jelinek, and P. Corneliussen. 1975.
FDA's overview of the potential health hazards associated
with land application of municipal wastewater sludge, p.
214-217. In Proceedings of the Second National Confer-
ence on Municipal Sludge Management and Disposal.
Information Transfer, Inc., Rockville, Maryland.
4 Burge, W. D., W. N. Cramer, and E. Epstein. 1977.
Pathogens in sewage sludge and sludge compost. Amer.
Soc. Agr. Eng. Trans. (In Press).
5 CAST. 1976. Application of sewage sludge to cropland:
Appraisal of potential hazards of heavy metals to plants
and animals. Report No. 64. Council for Agricultural
Science and Technology (CAST), Ames, Iowa. 63 p.
6. Chaney, R. L, and P. M. Giordano. 1977. Microelements as
related to plant deficiencies and toxicities, p. 234-279. In L.
F. Elliott and F. J. Stevenson (ed.) Soils for Management
and Utilization of Organic Wastes and Wastewaters. Soil
Sci. Soc. Amer., Madison, Wisconsin.
7 Chaney, R. L. and S. B. Hornick. 1977. Accumulation and
effects of cadmium on crops. In Proceedings of First
International Cadmium Conference. Held January 31 to
February 2, 1977, San Francisco, California. Metals
Bulletin (London). (In Press).
8 Colacicco, D., E. Epstein, G. B. Willson, J. F. Parr, and L.
A. Christiansen. 1977. Costs of sludge composting. Agri-
cultural Research Service, Northeast Regional Publication
No. 79. USDA, Beltsville, Maryland. 18 p.
9. Epstein, E., G. B. Willson, W. D. Burge, D. C. Mullen, and
N. K. Enkiri. 1976a. A forced aeration system for
composting wastewater sludge. J. Water Poll. Cont. Fed.
48.688-694.
10. Epstein, E., J. M. Taylor, and R. L. Chaney. 1976b. Effects
of sewage sludge and sludge compost applied to soil on
some soil physical and chemical properties. J. Environ.
Qual. 5:422-426.
]| Epstein, E., and G. B. Willson. 1975. Composting raw
sludge, p. 245-248. In Proceedings of the Second National
Conference on Municipal Sludge Management and Dis-
posal. Information Transfer, Inc., Rockville, Maryland.
12. Epstein, E. 1975. Effect of sewage sludge on some soil
physical properties. J. Environ. Qual. 4:139-142.
13. Farrell, J. G., 1974. Overview of sludge handling and
disposal, p. 5-10. In Proceedings of the National Confer-
ence on Municipal Sludge Management. Information
Transfer, Inc., Rockville, Maryland.
14. Farrell, J. B. and G. Stern. 1975. Methods for reducing the
infection hazard of wastewater sludge, p. 19-28. In Radia-
tion for a clean environment. International Atomic Energy
Agency, Vienna, Austria.
15. Lewis, G. P., W. J. Jusko, L. L. Coughlin, and S. Hartz.
1972. Cadmium accumulation in man: Influence of smok-
ing, occupation, alcoholic habit, and disease. J. Chron. Dis.
25:717-726.
16. Parr, J. F., E. Epstein, and G. B. Willson. 1977. Compost-
ing of sewage sludge for utilization as a fertilizer and soil
-------
Impacts—Heavy Metals 133
conditioner. In Organic Materials as Fertilizers in Asian
Countries. Soils Bulletin No. 29. Food and Agriculture
Organization, Rome, Italy (In Press).
17. Sommers, L. E. 1977. Chemical Composition of sewage
sludges and analysis of their potential use as fertilizers. J.
Environ. Qual. 6:225-232.
18. Willson, G. B., E. Epstein, and J. F. Parr. 1977. Recent
advances in compost technology. In Proceedings of the
Third National Conference on Sludge Management Dis-
posal and Utilization. Information Transfer, Inc., Rock-
ville, Maryland. (In Press).
-------
Disposal and Alternate Uses
of
High Ash Papermill Sludge
John S. Perry and Dean I. Schultz
Owen Ayres & Associates Inc.
Eau Claire, Wisconsin
INTRODUCTION
The purpose of this discussion is to provide practical applica-
tion data and design criteria for landfill disposal and alternate
uses of high ash papermill sludge. Laboratory data from field
samples and from sludge sampled prior to disposal have been
utilized to develop design constants for construction and
monitoring of disposal and alternate use practices. The discus-
sion includes a description of the disposal site, sludge characteri-
zation, results and significance of chemical and geotechnical
sludge properties, and the use of derived constants for landfill
and alternate use design.
Background
The Brown Company papermill in Eau Claire, Wisconsin
produces absorbent paper products from recycled paper. In the
reclamation process, a substantial volume of wastewater is pro-
duced which must be purified prior to discharge. In 1974 a pri-
mary treatment system utilizing neutralization, coagulation,
sedimentation, and vacuum filtration to remove suspended
matter from the waste began operation. The sludge generated
from this facility presented a significant disposal problem
(200-250 wet tons per day) and was initially disposed of at the
municipal landfill. Limited capacity and an impending closure
order made the future of this disposal method uncertain. Hence
the papermill embarked upon a program of locating and
designing a suitable landfill for sludge disposal. Concurrently,
studies were begun to define the physical and chemical sludge
properties as they would relate to landfill disposal.
Disposal Site Characteristics
Location Criteria
Landfill site location criteria were first defined, with the
geologic setting being of principal importance. In general, a site
with significant soil thickness above either groundwater or
bedrock was desired, with soils of low permeability being most
desirable. The site should be located a minimum of 1/4 mile
away from the nearest down-gradient water supply well. Also of
importance were haul distance and the quality of roads between
the mill and the disposal site. The site must also be properly
zoned or have a reasonable probability of being rezoned, must
provide for a minimum life of 7-10 years, must be socially,
politically, and environmentally acceptable, and must be
available for purchase at a reasonable price.
Physical Site Setting
The geology of the general Eau Claire area does not provide
for a site location in an area of heavy soils within 15 miles of the
mill. The site selected did, however, provide some forty feet of
fine sand soils above groundwater and/or sandstone bedrock.
The site was within eight miles of the mill, with all linking
highways being of adequate construction to carry haul vehicles
year-around. The 33 acre site was zoned agricultural (suitable
for landfilling purposes) and would provide for approximately
10 years of disposal volume. The site was naturally screened
from view on three sides and could be easily developed to
minimize aesthetic disruptions to the area.
The selected site is situated on top of an alluvial deposit on the
order of 100 feet in thickness. Flat open agricultural fields
dropping abruptly to eroded and gullied streambeds (as much as
60 feet vertical) typifies topographic trends at the site.
Area geology consists of sedimentary late Cambrian sand-
stone hills, overlying the Precambrian crystalline basement.
Deep valleys have been cut to the crystalline basement by melt
waters of Pleistocene glaciation, filling the valley with thick de-
posits of sand and gravel.
Soils at the site consist of medium to very fine-grained quartz
sand, deficient in fines. These subsoils have permeability
coefficients of from I * 10 4 cm/ sec to 8.6 x 10 1 cm/sec.
Bedrock lies entirely below the phreatic surface by some 40 feet.
Sludge Composition
The dry solids fraction of the sludge consists primarily of
Kaolin clay (54%) and paper fiber (45%). The waste treatment
process is responsible for adding minor amounts of chemicals
such as alum, activated silica, and polymers. There are also
many impurities from the paper making process present in
minute amounts. Table I contains a typical chemical analysis of
the sludge listing the principal elements present.
TABLE I: Chemical Composition of High Ash Sludge
Moisture, % (range)
Ash, %
Aluminum, %
Calcium, %
Iron, %
Magnesium, %
Silicon, %
Titanium, %
Water Soluble Alkalinity, as
CaC03, %
pH of cold water extrace
70 - 75
51.62
12.20
0.15
0.21
0.25
10.68
2.32
0.163
6.28
All analyses except moisture and pH were performed on
ovendry samples. Basis for other analyses were: ash, ignited at
800°C for 1 hour; pH, TAPPIT 435 ts—52; alkalinity, TAPPIT
-------
Papermill Sludge 135
428 su-67 and Standard Methods', final pH of titration, 3.70;
metals, emission spectrography.
Geotechnical Engineering Characteristics
Physical Properties
Consistency Limits. Oven- and air-dried samples of the
sludge were tested for Atterberg indices in accordance with
ASTM-D 423 and ASTM-D 424. Distilled water was added to
increase the moisture content beyond the liquid limit. Numerous
liquid limit determinations were then made as the samples were
dried from wet of the liquid limit to dry of the liquid limit.
Plastic limit values were determined for specimens dry of the
liquid limit.
The consistency limits were used to identify the general
engineering characteristics of the sludge, as compared to
naturally occurring cohesive soils. The plasticity chart, Figure 1,
(A. Cassagrande4) implies that the sludge will act similarly to
elastic silt (MH) and/or organic clay (OH).
It is noted that the data points representing oven-dried
samples had lower liquid limit and plasticity values. This shift in
the consistency limits results from a decrease in organic content
from burning of organics during oven drying at 110°C.
Specific Gravity of Solids. Air-dried samples of the material
were tested in accordance with ASTM-D 854-72. Specific
gravity of the solids fraction, based on 8 tests is 1.85 ±0.01.
Knowledge of the specific gravity is important to weight-vol-
ume calculations. Specific gravity of the sludge is expected to
vary somewhat with changes in plant operation and organic
content.
Moisture-Density. The placement of "fresh" saturated sludge
in confined areas will be difficult. It is obvious that densification
will be unaffected by initial compaction efforts due to the
saturated clay-like character of the sludge.
Grainsize Analysis. Hydrometer analysis tests were attempted
on the sludge in accordance with ASTM-D 422-72. Attempts to
disperse the clay-cellulose mixture using calgon were unsuccess-
ful, even after slaking for 24 hours. Attempts at grainsize analy-
sis were inconclusive. The physical properties determined by
laboratory tests are summarized in Table 11.
TABLE II: Physical Properties
Consistency Limits (Range)
w-| Liquid Limit (%)
240 -
300
Wj Plasticity Index {%)
138 -
166
Specific Gravity of Solids Fraction
1.85+
01
Moisture Content (% Dry Solids) (Range)
270 -
300
Density ->
Minimum @ 270% (lbs./ft. )
68
Maximum 0 181% , After 4 TSF Consol. Press.,
(lbs./ft.3)
74
Ash Content (% of Dry Solids)
54
Organic Content (7° of Dry Solids)
46
Predominant Clay Mineral
Kaoli n
Sample Preparation
Trimming of the wet fibrous sludge for tests was difficult with
conventional laboratory tools (i.e., wire saw, knife, etc.). The
difficulty with sample preparation experienced in early tests
(1974-1975) resulted in the use of a small, high-speed rotary drill
with a disc-type cutter head, as referenced by Andersland2. This
trimming technique proved satisfactory. Air and oven-dried
samples used for consistency limits and specific gravity tests
were prepared by grating after drying to constant weight.
AIR DRIED
A FRESH PAPER MILL SLUDGE FROM CONVEYOR
0 AGED PAPER MILL SLUDGE FROM LANDFILL
OVEN DRIED
O FRESH PAPER MILL SLUDGE FROM CONVEYOR
O AGED PAPER MILL SLUDGE FROM LANDFILL,
OH
MH
_l
.V
-I 1 1 I ' ' '
A
/
/
\
\
/ /
/ VARIOUS TYPES /
/ OF PEAT /
I
ORGANIC CLAYS AND
HIGHLY ELASTIC ORGANIC
SILTS AND SILT-CLAYS
-L.
40
60
120 160 200
LIQUID LIMIT. W,
240
260
320
360
400
Figure 1: Plasticity Chart
-------
136 Papermill Sludge
Later samples (December, 1976 and January, 1977) prepared
for consolidation testing of the sludge were dispersed with
distilled water. The dispersed sludge was allowed to drain
through Whatman No. 40 filter paper to an average moisture
content of 260% based on weight of dry solids. This wet-
dispersed technique of sample preparation appears to provide
more uniform compaction and a dependable 100% saturated
condition.
Mechanical Properties
Direct Permeability Tests. Constant head, variable head, and
falling head permeability tests were conducted using a Soiltest
605 Permeameter and a 4-inch Proctor mold. A constant head
test was performed in a 7-inch I.D. by 30-inch high column in
conjunction with leachate determinations. A 3.7 inch thick
sludge cake was subjected to an 18.2 inch head of distilled water
for 2,709 hours (3.76 months). The test was designed to (1)
collect samples of leachate for qualitative analysis and, (2)
measure permeability. An average coefficient of permeability of
1.42 * 10~6 cm/sec was measured over the test period.
Determinations of the coefficient of permeability from the
other direct test methods were inconclusive. The possible
sources of error appear to result from (1) leakage between the
sludge cake and the wall of the permeameter, (2) incomplete
saturation, and (3) non-uniform compaction. Calculations of
the coefficient of permeability from the ten direct tests are in the
range of 1.0 x 10-5 cm/sec to 3.6 x 10-7 cm/sec.
Indirect Permeability Determination. Calculations of the
coefficient of permeability, k, from the deformation vs. log of
time (S vs. log t) curves showed significant decreases in
permeability with decreases in void ratio, e, and with increases in
the coefficient of consolidation, cv. Figures 2 and 3 show plots of
k vs. cv and k vs. e, respectively,
in which k = m^fiw, and cy = Ty D2 where:
t
T = Time factor
HV = Sludge cake thickness
D = H/2
t = Laboratory time
£w = Unit weight of water
Oedometer Tests. One-dimensional consolidation tests were
performed using a Soiltest C-220 Levermatic Machine to
estimate volume changes resulting from expulsion of pore
water, and magnitudes of settlement under load.
Four consolidation tests were performed; one on undisturbed
sludge from the municipal landfill and three on samples from the
discharge point at the papermill. The undisturbed test used load
durations of 24 hours, and load durations of tests of fresh sludge
varied from 24 hours to two weeks. In all cases, a load increment
ratio of 2 was used.
Void ratio vs. log of pressure (e vs. logp) curves are presented
on Figures 4 through 7 and reflect primary and secondary
consolidation. The e vs. log p curves for undisturbed sludge
consist of two branches; a relatively flat initial portion, and a
straight line, or virgin branch. The unadjusted curves for the
"fresh" material have an initial curvature at low load increments
which approaches a straight line with increased load. Figure 4 is
corrected to primary consolidation after Ladd3. The e vs. log p
curves from the tests show good agreement with settlement
10"
10"
10
-6
10'
&
&
A
~
A
10
-2
10
0
~
El AGED PAPER MILL SLUDGE FROM LANDFILL
& FRESH PAPER MILL SLUDGE FROM CONVEYOR
10
10"
10
-6
COEFFICIENT OF CONSOLIDATION, C„, CM*/SEC0ND
Figure 2: Coefficient of Consolidation vs. Permeability
-------
Papermill Sludge 137
characteristics of organic clays of normal and underconsoli-
dated load histories. It is concluded from the curves that
significant volume change will occur under small load incre-
ments and I or self-weight.
Unconfined Compressive Strength. U nconfined compressive
strength (qu) tests (S„=C) were performed on undisturbed
samples utilizing ASTM-D 2166-72. The strain ( e ) rate was
controlled at one per cent per minute until failure was attained.
The results of the Su=C tests are presented in Table 111 and
showed marked increases in shear strength as a result of self-
weight consolidation.
TABLE III: Unconfined Compressive Strength of Normally
Consolidated High Ash Sludge
Specimen
w
No
L-l
)
157
2
147
3
129
4
124
5
125
Densi ty
(PCF)
76
75
79
79
80
&
Sy = C
(f PSF)
fil
990
495
10.7
880
440
14.6
875
430
9.5
470
235
5.9
675
335
8.9
Triaxial Shear Strength. Triaxial shear strength,
consolidated-undrained (CU) and unconsolidated-undrained
(UU), were measured for undisturbed and "fresh" samples as
shown in Table 4. The primary objective of the measurements
was to determine the relationship of shear strength (S), and
effective stress (5), at failure.
The strength data interpreted in terms of effective stresses,
(Ti, ah (Figure 8) indicated little cohesion. Shear strength of
the sludge increases with increased effective stress accompany-
ing conslidation, as in naturally occurring soils.
The first annual report of experimental studies of high ash pa-
permill sludge by Andersland2 showed that theories of soil
mechanics are applicable to make reasonable predictions of the
engineering behavior of sludge. Laboratory test results from
studies reported in this paper showed good agreement with data
provided in Andersland's study.
Porewater and Leachate Composition
The moisture present in the fresh sludge (pore water)
comprises 70%-75% of the sludge on a weight basis and is
important from a disposal standpoint as much of it will be
expelled during consolidation. Table V contains a typical pore
water analysis.
TABLE V: Chemical Composition of Pore Water
pH
6.4
Alkalinity, mg/1 as CaCOj
44
Hardness, mg/1 as CaCCU
72
Chloride, mg/1
51
COD, mg/1
344
BOO, mg/1
213
Total Dissolved Solids, mg/1
818
Specific Conductance, umhos @ 25°C
720
Iron, mg/1
2.2
Sodium, mg/1
230
Sulfate, mg/1
230
Calcium, mg/1
41
~ AGED PAPER MILL SLUDGE FROM LANDFILL
& FRESH PAPER MILL SLUDGE FROM CONVEYOR
10
-8
&
O
O
Ui
in
10
-r
~
0 ~_
s
4
UI
2
at
ui
-------
138 Papermill Sludge
TABLE VI: Surface Water and Groundwater Quality Estimates Estimates Under Alternate Design Methods
Spec.
No.
Type
w
(%)
^3
(psi)
fl"5
(psi)
(Psi)
*3
(psi)
(0\ +
2
A
I
It £
1
(S)
(psi)
1
CU
195.8
6
4.4
3.8
2.20
4.4
0.87
38
1
2
cu
189.8
9
7.50
0.04
--
--
--
--
--
3
CU
165.8
13
9.2
4.0
9.0
13.6
0.99
12.3
1
4
cu
200
9
11.0
8.0
1 .0
6.5
0.73
4.0
3
5
cu
162.7
12
14.5
9.0
3.0
10.2
0.62
6.9
3
6
uu
194.7
3
5.0
2
1 .0
6.5
0.40
2.0
1.25
7
uu
813.2
6
7.4
1.7
4.3
8.0
0.23
2.9
1 .25
NOTE :
e VS LOG P CURVE
£) (INCLUDES SECOND*** CONSOLIDATION)
& END OF PRIMARY CONSOLIDATION, t.
100
Figure 4: Void Ratio vs. Log Pressure for Fresh Sludge from Test 2/77
-------
Papermill Sludge 139
e0 = 5.99
1
1
1
1
1
1
1
I
Cc:
61 - e 2
Io9,oP2/pi
PRESSURE - TONS PER SOUARE *OOT
Figure 6: Void Ratio vs. Log Pressure for Fresh Sludge from Test of 2/75.
-------
140 Papermill Sludge
.10
PRESSURE
TONS
.50 10
PER SQUARE FOOT
Figure 7: Void Ratio vs. Log Pressure for Aged Sludge from Test 2/75
TEST NO
SAMPLE NO
<5
1
1
6
4.39
1039
2
2
9
7 50
16 50
3
3
13
9.21
22 21
Also of interest is the quality of water which may be
discharged from the sludge as a result of the leaching effect from
surface water percolating through the sludge in a disposal site.
As previously mentioned, a leaching study was performed
utilizing distilled water over a period of 2,709 hours, with
samples being collected and analyzed at selected intervals. The
results of these tests appear in Figures 9 thru 11. These tests were
conducted approximately two years earlier than those listed
above for the pore water and indicate some difference in the lev-
els of certain parameters. However, the general trends of the
leachate quality are applicable and indicate that after reaching
an early peak, the levels of leachate parameters generally
decrease with additional leaching.
)0 IS 20 26
VOLUME THRU PERMEAMCTER - I ITERS
••a 8*5
normal stress
TEST NO
1
2
3
TEST TYPI
c u
C.U
C.U
SB PSI
004 pa
4.0 RSJ.
SHI
4947
4805
1775
3.129
3.567
9r
•M%
1000%
655
td
OMSSI.
0446 V
0403%«
W (INITIAL
277.3%
267.0 %
265 3
W {FINAL)
i*M*
I0M %
165.6 %
KXH
i S ioo-
X
J o
Figure 8: Triaxial Test Data for Fresh Paper Mill Sludge
» To ' * ' * 20 ' ' ' 29 ' ' '
VOLUME THRU PERMEAMCTEft - LITERS
Figure 9: Leachate Analyses Conductivity, TDS, pH, Alkalin-
ity, Hardness
-------
Papermill Sludge 141
Site Design
Principal site design objectives were to provide (1) an envi-
ronmentally acceptable disposal site, (2) an efficient and eco-
nomical site to operate, and (3) an aesthetically acceptable
operational and final use plan. The primary concerns with
respect to protection of the environment center around the
protection of ground and surface water quality. Utilizing the
data gathered during the leachate and porewater quality
analyses and the geotechnical investigations, an estimate of the
effects of pore water release was performed. The estimates were
initially made assuming a filling concept allowing for rapid
consolidation of the sludge mass. The procedure involves the
placement of sand drainage blankets between relatively thin
(10') lifts of sludge. These blankets will reduce the length of the
drainage path and increase the rate of release of pore water.
Such a filling procedure accelerates consolidation, thus reduc-
ing the time period over which pore water may adversely affect
the environment. The principal disadvantages are that the rapid
rate of pore water release places a greater strain on the
environment and the method of construction is more costly.
Water quality effects projected for this method of filling are
summarized in Table VI. The projected values are based upon
an assumption of "zero" attenuation of pore water by the soil
system and reflect only dilution by surface and groundwater
flows. This assumption was utilized only to provide a "worst
case" approximation of environmental effects. Because the
waste is amenable to biological treatment processes, it is
anticipated that the soil regime will provide adequate treatment
to relieve the danger of environmental degradation. Due to the
proximity of an existing well (Vi mile down gradient), the
potential location of future wells in the near vicinity of the site,
and the inability to predict the attenuation capability of the soil,
a second method of filling was investigated which would reduce
the rate of porewater release.
TABLE IV: Triaxial Test Results of High Ash Sludge
GROUNDWATER OUAI TTV
SURFACE WATER QUALITY
PARAMETER
Existing
Rapid
Consolidation
Method
Massive
Fill
Method
Existing
Rapid
Consolidation
Method
Massive
Fill
Method
Alkalinity,
mg/1 as CaC03
27
29.5
27
20
20.7
20.2
Hardness,
mg/1 as CaC03
50
53.2
50
45
45.2
45.1
Chloride, mg/1
6
12.6
6.1
11.8
12
11.8
COO, mg/1
< 20*
<67 .4**
<20.9**
9
<10.5**
<9.3**
BOD5, mg/1
<10*
<39.7**
<10.6**
2
< 3.0**
<2.2**
Total Dissolved
Sol ids, mg/1
138
237
140
95
98.7
96.2
Iron, mg/1
—
—
—
0.9
—
—
Sodium, mg/1
11
43.0
11.6
4.3
5.3
4.5
Sulfate, mg/1
10
42.1
10.6
—
—
—
Calcium, mg/1
13
17.1
13.1
10.6
10.8
10.7
* Estimated groundwater quality
** Based upon estimates of groundwater quality.
S » 18 tO t» 10
VOLUMI THRU PCRMCAMCTCR - UTCRS
Figure 10: Leachate Analyses Chloride, Sulfate, Color, Turbid-
ity
Figure 11: Leachate Analyses Cod, Bod, Calcium, Sodium, Iron
-------
142 Papermill Sludge
This approach involves the deposition of one massive 30 foot
lift of sludge, creating a longer drainage path for porewater
release and resulting in a slower rate of release. This slower rate
of consolidation would place less strain on the environment but
would require a correspondingly greater time to achieve final
consolidation. The rate of release under this method was
estimated to be approximately one-tenth that of the former
method. Since rapid consolidation was not required from the
standpoint of land use or development, it was decided to
incorporate this filling procedure in the final design. To insure
the integrity of the surface water and groundwater resources, a
linear and porewater collection system were incorporated into
the design. This sytem would allow very slow leakage of
porewater to the soil system (the liner is composed of consoli-
dated sludge) and yet would allow for collection and removal of
the porewater if necessary. Water quality effects projected for
this method of filling (assuming no porewater removal and zero
soil attenuation) are summarized in Table VI.
Site Operation
The site will be constructed as a combination trenching,
area-fill operation. A series of three trenches will be constructed,
each surrounded by a dike constructed above natural grade. The
bottom and sides of the resulting cells will be lined with 4 feet of
sludge and a two foot thick sand drainage blanket will be placed
over the sludge liner prior to filling operations. The sand blanket
will serve as a collection medium and provide a double drainage
condition for the liner and fill consolidation. The liner and sand
blanket will serve to collect and transport the expelled pore-
water to a specially constructed collection trench from which it
will be piped to a pumping station for removal, if required.
Mass filling of each trench will be.accomplished by end-
dumping of sludge near the top of the active filling face. The
entire 30 foot depth will be placed at once by performing an
over-the-bank filling operation. A low-ground-pressure, track-
operated bulldozer will push the sludge up to and over the edge
of the advancing sludge bank.
As the sludge is placed, porewater will be released and will
flow into the sand blanket. In general, the intent of operations
will be to not remove liberated porewater from the fill unless
degradation of the groundwater or surface water warrants such
removal. It would appear that the rate of porewater release by
the liner will be so small as to have negligible effect on the
groundwater system. A series of groundwater monitoring wells
will be established immediately down-gradient from filling
operations and will be used to monitor groundwater quality.
Should the results of this monitoring indicate significant
degradation of the groundwater, porewater will be removed
from the lined site and will be transported to Brown Company's
wastewater treatment facility for disposal.
Trafficability
At initial placement, the sludge is at or above its liquid limit
moisture content. The sludge fill acts similarly to a hydraulic fill
and is quite unstable under wheel or conventional track-
mounted equipment (low-ground pressure track-mounted
equipment has proved acceptable). Roads constructed of gravel
over filter cloth will provide access to the active fill face over
previously placed sludge. Successful use of this construction
technique has been demonstrated by performance of logging
roads in Alaska and haul roads over silt and marsh soils in
Indiana, to cite two examples.
Settlement
Consolidation of the sludge may be divided into two
fundamental parts; (1) primary consolidation, and (2) secondary
consolidation (Figure 12). Both are time load dependent
quantities. Settlement results from vertical stress acting on a ho-
rizontal plane at a depth, z. The total vertical stress, av, is equal
to the weight of all matter that lies above the plane. High ash pa-
permill sludges contain large volumes of water. When depos-
ited in a confined space, excess pore water pressures, fa , are
created and exert a hydrostatic pressure on the sludge fabric.
This hydrostatic pressure reduces the effective stress between
TIME ( LOG SCALE )
-------
Papermill Sludge 143
solid particles by the quantity, /x .Therefore, the effective stress,
(?i, is equal to total stress minus hydrostatic pressure ( o\ -/u. ).
In practice, the average vertical effective stress, 5V, is taken at
midheight of the sludge layer.
Sludge Fill. The initial average effective stress, avi, acting at
midheight of the 30-foot thick sludge layer is 144 PSF (Figure
13). In addition, a final natural soil cover, 2 feet thick, will be
placed over the waste. Thus, A
-------
144 Papermill Sludge
Table 8: Sludge Fill Settlement Computation From e vs. log p
Curve, 2-77
tsf
rvf*. TSF
0-10
Ft.
0.024
0.124
4.55
3.72
0.83
0.15
1.S0
10-20
Ft.
0.092
0.176
4.05
3.50
0.55
0.109
1.09
20-30
Ft.
0.120
0.220
3.7$
3 33
0.42
0.088
0.88
Total Settlement, AH^ = 3.47 Ft.
from e vs. log p curve at mid-height of each layer.
Liner. Permeability tests of the sludge (1974) implied that a
minimum coefficient of permeability, k, of 1 * 10-6 cm/sec is
characteristic of the sludge. In addition, the solids fraction of the
sludge is composed, in part, of calcium kaolinite clay, a mineral
resistant to chemical attack and weathering. The physical and
mechanical properties of the clay-like sludge were studied to
determine the suitability of the sludge for use as an impervious
liner.
Sludge permeability has been shown to be a function of voids
ratio and degree of consolidation. Calculation of the coefficients
of permeability from the 8 vs. log t curves have been computed
by the equation:
kv = mvcvfiw
— Eq. (3)
in which; kv
mv
cv
£w
= Coefficient of permeability, cm/sec
= Volume compressibility, g/cmJ
= Coefficient of consolidation, cm2 /sec
= Unit weight of water, gm/cm3
Two vertical stress conditions were considered in the design of
the liner: (1) a sand blanket 2 feet thick placed on top of the 4-
foot sludge liner (assumed to have a unit weight of 110 PCF)
and, (2) the stress transmitted to the sludge liner from placement
of the 30 feet of sludge in the confined cell (Figure 14).
From Figure 15 and Table 9, the average effective stress and
total stress were obtained and total settlement was computed
using Eq. (1). Total settlement under the effect of the sand
blanket is estimated as AH| = 1.2 feet. At the end of primary
consolidation, t^,, using laboratory data Irom Table 7 and Eq.
(3), the liner will have a coefficient of permeability of 1.18 * l(M
cm/sec. The time required for consolidation of the liner is
estimated to be 32 days based on Eq. (2). A coefficient of
permeability of 2.3 * 10 * cm/sec is anticipated at the end of the
consolidation period.
Liner consolidation will result in the release of porewater in a
volume equal to the total settlement and will amount to
approximately 9 gallons per square foot of liner. Because the
liner will have a double drainage surface, one-half of this
liberated porewater will be released to the soil beneath the liner
and one-half will flow to the sand blanket above the liner.
Thus, for each square foot of liner placed, approximately
seven inches of porewater will be released to the soil beneath it
over the 32 day consolidation period. Following consolidation,
the liner will have a permeability of approximately 2 * 10-8
cm I sec, or 0.25 inches per year.
Alternate Uses
Laboratory tests have demonstrated that the sludge (1) gains
significant shear strength from consolidation, (2) is of low
permeability, (3) has a total unit weight, after consolidation, of
between one-half and three-fourths that of natural clay soils and
three-fourths that of natural sand soils and, (4) upon complete
consolidation, is relatively stable.
Utilization of the sludge as an impervious cap material has
been undertaken at a local municipal landfill. The cap has been
designed to reduce leachate production by limiting infiltration
of surface water and is currently in service.
Construction of farm pond and lagoon liners of the sludge, in
regions of highly permeable soils, has promise as an alternate
use, also. In two instances to date, its use as a lagoon liner has
been proposed to the Wisconsin Department of Natural Re-
sources. Unfortunately, its use has been viewed with skepticism
by the regulatory agency.
-------
Papermill Sludge 145
Diversion and/or capture of water using the sludge in the
form of a vertical cut-off wall has shown some success. This
application of the sludge has also been utilized at a local landfill
site.
Future use of the sludge may include light weight fill
applications in lieu of heavier natural soil, where soft or
compressible foundations exist.
Conceivably, properly planned and surcharged sludge dispo-
sal sites may be ultimately developed as recreational areas or
parks. Observed gains in shear strength, due to consolidation,
suggest that light structures may be supported on the sludge
when properly consolidated.
Full scale on-going tests of the behavior of the sludge under
elementary conditions, such as liners surcharged with refuse and
as cap material, are in process. Field instrumentation and
observation of the sludge behavior, coupled with additional
supportive laboratory testing, may further confirm the potential
application of the sludge as a material of construction.
ACKNOWLEDGEMENTS
The Brown Company, Eau Claire, Wisconsin, provided much
of the financial assistance needed to accomplish this work
through their investigation of physical and mechanical proper-
ties of the sludge for disposal. Portions of this paper were
reviewed by Gary Norris of the University of Wisconsin, Civil
and Environmental Engineering Department, Madison, Wis-
consin.
Grateful acknowledgement is made to the Brown Company
and Gary N orris for their assistance and critical review of the pa-
per.
Special thanks are due to James Strigel for conducting many
of the laboratory tests.
REFERENCES
1. American Public Health Association, Standard Methods
for the Examination of Water and Wastewater, 13th ed.,
Washington, D.C., 1971.
2. Andersland, O. B.; Vallee, R. P. and Armstrong, T. A."An
Experimental High Ash Papermill Sludge Landfill: First
Annual Report," Report No. EPA-670/2-74-076a, Dec.,
1974, U.S. Environmental Protection Agency, Cincinnati,
Ohio.
3. American Society of Testing and Minerals, "Book of
ASTM Standards," Part 15, Philadelphia, Pennsylvania.
4. Cassagrande, A., "Classification and Identification of
Soils," Trans. Am. Society of Civil Engineers,
113-API-930, 1948.
5. Ladd, C. C. (1973) "Settlement Analysis for Cohesive
Soils," MIT Dept. ofC.E. Res. Ref. R71-2 (Revised 1973
for N.Y. MET. Section ASCE SMFD Seminar).
6. Lambe, T. William, "Soil Testing for Engineers," John
Wiley & Sons, Inc., New York, 1951.
7. Lambe, T. William, and Whitman, Robert V., "Soil
Mechanics," John Wiley & Sons, Inc., New York, 1969.
8. Peck, Ralph B.; Hanson, Walter E. and Thornburn,
Thomas HFoundation Engineering," 2nd Edition, John
Wiley & Sons, Inc., New York, 1973.
9. Scott, Ronald F., "Principles of Soil Mechanics," Addison-
Wesley Publishing Company, Inc., Reading, Massachu-
setts, 1963.
10. Terzaghi, Karl and Peck, Ralph B., "Soil Mechanics in
Engineering Practics," 2nd Edition, John Wiley and Sons,
Inc., New York, 1967.
11. Wu, T. M., "Soil Mechanics," 3rd Edition, Allyn and
Bacon, Inc., Boston, 1967.
AT PLACEMENT;
TSF
0.0
-0.07
0.14
TSF
0.0
-0.06
0.12
AT FULL CONSOLIDATION UNDER 2.0' SAND BLANKET, SLUDGE WASTE AND FINAL SOIL COVER:
2' (SAND BLANKET)
1.28
1.12
1.00
.13
0.28
—0.29
0.29
Figure 15: Determination of Effective Stress, 5» (Mid Point of Liner)
TABLE IX: Settlement Computation from e vs. log P Curve, 2-77
(X,
CfVf
eo
e f
Ae
0e
l + e0
& H
TSF
TSF
(FT.)
0.01
0.29
4.78
3.10
1.68
0.29
1.16
TOTAL SETTLEMENT, &H =1.16"
-------
Environmental Assessment
of the Disposal
of Industrial
Wastewater Residuals
in a Sanitary Landfill
Daniel J. McCabe
Environmental Enterprises Incorporated
Cincinnati, Ohio
INTRODUCTION
I his paper discusses two case studies involved in the
assessment of the environmental impact of the disposal of two
industrial wastewater sludges in a sanitary landfill. The sludges
are generated by physical separation of settleable solids in
lagoons prior to discharge of the effluents to a municipal sewer
system. As such, they are sludges resulting from the pretreat-
ment of industrial wastewaters. Both sludges have been accumu-
lating in lagoons for a number of years, and removal of the
materials is necessary for continued wastewater treatment. The
environmental impact of the disposal of these wastewater
sludges in a local sanitary landfill was assessed so that state EPA
approval could be obtained for disposal of the residuals at this
location.
The first chemical manufacturing plant utilizes three lagoons
in its wastewater pretreatment process. Wastes are collected in a
central sump from all manufacturing facilities. These wastes
include sanitary and industrial wastewater and some drainage
from storage areas and parking facilities. These wastes are
pumped to a primary lagoon where sedimentation and equaliza-
tion occur. The wastewater is subject to large variations in
concentrations of waste materials, as well as significant varia-
tions in pH. The effluent from the primary lagoon, (pHwl.O
s.u.), is neutralized with lime and directed into one of two sec-
ondary lagoons. The secondary lagoons allow sedimentation of
the suspended solids in the neutralized wastewater prior to
discharge to the municipal sewer system. Both secondary
lagoons are equipped with an underdrainage system to allow
dewatering of the sludge.
The second manufacturing facility utilizes three lagoons for
wastewater pretreatment prior to discharge of the effluent to the
municipal sewer system. The first two lagoons function as
primary settling facilities. In the third lagoon, small quantities of
caustic are added to maintain a balanced pH. No underdrainage
system is provided in these lagoons. The settleable solids have
been accumulating in the lagoons for a number of years, and
removal is necessary for continued wastewater treatment.
Samples of both wastewater sludges were secured and a
number of chemical analyses were performed. Approval was
then requested from the state regulatory agency for disposal of
the residuals in a local sanitary landfill.
The regulatory agency essentially gave us two options. The
first of these was to assume that the sludge was a hazardous
material and wait until a landfill was approved for hazardous
wastes. The second of these was to do a more thorough study to
show that the waste was not a hazardous material. Due to the
need for immediate removal of the sludges, the second approach
was adopted for both industries. The approach taken was to
prove that the sludges were a nonha/ardous, solid, material at
which time they could be disposed ol in any conventional
landfill.
The approach developed to prove the safety of the material
requiring disposal included the following steps:
(1) Multiple core samples were secured from various sections
of the lagoons.
(2) Detailed chemical analysis of the residuals were per-
formed to accurately define their composition.
(3) Leaching tests were conducted to characterize the organ-
ics and metallics which would be leached.
(4) Toxicity tests were conducted utilizing non-acc\imated,
activated sludge type organisms.
(5) The environmental impact of the disposal of the waste-
water residuals on the groundwater was predicted,
(6) An operational plan was developed and submitted
indicating how the removal, transport, and disposal
operations would occur.
The same procedures were followed for both environmental
impact statements.
Sampling
Due to the fact that manufacturing operations have changed
since the lagoons have been operational, vertical samples of the
accumulated sludges were needed. Since different sedimentation
rates would apply to components within the wastewater; core
samples were taken at various locations in the lagoons to insure
that a representative sample was obtained. Coring devices were
used which extended to the base of the lagoons and all core
samples were combined and homogenized prior to securing
aliquots for analysis.
Chemical Analysis
Detailed chemical analysis of the sludges were undertaken to
define its composition accurately. The results of the analyses are
reported on Table I for both industries. Results on this table are
given in mg/kg on a dry weight basis except for total solids
which is reported on a wet weight basis.
The first part of this table gives the composition of industry # 1
sludge. There are a number of metal ions in this waste which are
significant from an environmental viewpoint. These metals
include Chromium, Lead, Zinc and Barium. It should be noted
that all the Chromium present is in the trivalent form and that
the probable chemical form of the Lead and Barium is the
sulfate form. This would result from the high concentration of
sulfate present in this sludge (7.4%) and the low solubilities of
Lead and Barium sulfate.
The sludge has a COD of greater-than 600,000 mg/kg with a
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Environmental Assessment 147
Table I—Industry #1
LAGOON RESIDUE CORE SAMPLE ANALYSIS
mgAg
mg/kg
Dry Weight
Dry Weight
Cadmium
2.84
Total Carbon
20,700 (2.07%)
Chromium
1,037.2
Total Organic Carbon
15,000 (1.5%)
Copper
165.13
Aluminum
26,200 (2.6%)
Lead
4,214.3
Barium
7,200
Nickel
57.32
Iron
14,200 (1.4%)
Zinc
4,394.5
Manganese
600
Mercury
2.271
Total Volatile Solids
27.50%
COD
604,000
Alkalinity
984,900
Hexavalent Chromium
8
Organic Acids
N.D.
Density
2.0832 g/cc
Calcium
117,363 (11.74%)
Cyanide
1.05
Magnesium
3262
Total Solids
38.20%
Sulfate
73,875 as SO. (7.39%)
4
BOD_
5
84,700
Table I—Industry #2
LAGOON RESIDUAL CORE SAMPLE ANALYSIS
mg/kg
mg/kg
Parameter
Dry Weight
Parameter
Dry Weight
Aluminum
140,000.
Zinc
2.930
Barium
53.36
Sulfate
32,166.
Cadmium
1.08
COD
360,000.
Calcium
107.7
Total Carbon
336,319.
Chromium
12,095.
Total Solids
43.51
Copper
7,336.
Volume
1,950 yd3
Hexavalent Chromium
16.9 ug/kg
PH
6.4 s.u.
Iron
6,733.
Density
1.0688 g/cc
Lead
44,475.
Total Volatile Solids
55.22%
Magnesium
1.83
Alkalinity
13,552.
Manganese
25.41
Cyanide (includes
Mercury
5.54
nitriles)
63.76
Nickel
13.47
BOD^ (wet weight)
23,700.
Organic Acids
320.
BODg (dry weight)
73,600.
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148 Environmental Assessment
relatively low BOD (85,000 mg/kg) and total Carbon (21,000
mg/kg) content. This, together with a total volatile solids of
27.5% indicate a large inorganic fraction. The high alkalinity
(985,000 mg/kg)and total solids indicatea well neutralized solid
material.
The second part of this table gives the composition of the sec-
ond industry's sludge. This second sludge has an increased
carbon content (33.6%) while still containing high concentra-
tions of metal ions. Environmentally significant ions within this
sludge include Chromium, Copper, Lead, and Zinc. Once again
all Chromium is in the trivalent form and significant amounts of
sulfate (3.2%) are present. The total solids (43.5%) and pH
indicate a neutral, solid material.
The chemical analysis of the sludges revealed high values for
oxygen demand parameters and various metallic components.
Table II gives comparative data for municipal solid waste by
category. Comparison of the industrial sludge composition with
municipal solid waste indicates similarities in oxygen demand
parameters and differences in metallic ion concentrations.
Predictably the metallic ion concentrations are much lower in
municipal solid waste.
Leaching Tests
Additional identification of the organic portion of the sludge
was undertaken due to the concern expressed by the regulatory
Table II-
agency for these materials. Due to the complexity of the
materials found in sludges, an effort was made to identify the
organic materials which would be leached from the sludge in a
landfill environment. This involved the perl or ma nee of two
leaching tests, a rainfall, and acetic /butyric acid leaching test.
To simulate the rainwater effect upon leaching, distilled water
corrected to a pH ol 4.5 was added to the residual and placed on
a reciprocal shaker for one hour. This pH simulates the pH of
rainfall in the Ohio area, f ollowing liltration, the leachate was
analyzed for organic components and alkalinity.
The second test involved an aceticbutyric acid leaching
solution in a 2.1 ratio diluted to pH 4.0 with distilled water. This
also was contacted with the residual (or one hour and filtered.
The results of both leaching tests are included in Table 11.
The volume of diluent contacted with the sludge was calcu-
lated by considering the volumes of the completed landfill, the
volume of the sludge, and the water balance for the landfill in
question. The water balance method used was that developed by
the EPA1 for use in predicting leachate volumes from landfills.
In general, the leaching test results, as shown in Table U,
indicate that little organic material is being leached, and the
materials which do leach do not pose a significant environ-
mental problem in a landfill. One important consideration was
the presence of very low levels of chlorinated hydrocarbons in
the leachate. The highest concentration of the chlorinated
hydrocarbons obtained was in the acetic/butyric acid leach
-Industry #1
RAINFALL LEACHING TEST
Parameter
Value
ESTIMATED
QUANTITIES AR.
LEACHED
Alkalinity 26,065 mg/kg
Chlorinated Hydrocafcbons Not detectable by E.C.G.C.
Alcohol (Ethanol)
Aldehydes
Esters
Acids
Heavy Carbon Chain
Compound C^Q
.001%
Not detectable
Not detectable
Not detectable
.0002%
ORGANIC ACID LEACHING TEST
Parameter
Value
Alkalinity 1825 mg/1
Chlorinated Hydrocarbons Not detectable by E.C.G.C.
Alcohol*
Aldehydes
Esters
Acids
Heavy Carbon Chain
Compound C
20
.001%
Not detectable
Not detectable
Not detectable
.0007%
26 mg/kg
0
.000001%
0
0
.0000002%
ESTIMATED
QUANTITIES AR.
LEACHED
1.82 mg/kg
0
.000001%
0
0
0
.0000007%
*A11 data based on dry weight.
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Environmental Assessment 149
Table II—Industry #2
Parameter
LEACHING TEST ANALYSIS
Acidified Water Leachate
Organic Acid Leachate
COD
530.5
mg/1
554.8
mg/1
Chromium
0.13
mg/1
0.26
mg/1
Copper
0.01
mg/1
0.01
mg/1
Zinc
0.61
rag/1
1.47
mg/1
Lead
3.90
mg/1
5.60
mg/1
Organic components
Alcohols
2.2
mg/1
1.8
mg/1
Aldehydes
ND
ND
Esters
ND
ND
Chlorinated Hydrocarbons:
Beta BHC
1.1
ppb
1.6
ppb
Technical Chloridane
2.3 ppb
3.1
ppb
ND ¦ ^1 ocb
which were below 4 ppb for industry #2. These very low
quantities of chlorinated hydrocarbons in the leachate would
not exert any measurable effect on the decomposition processes
which occur in a landfill or upon wastewater treatment plant
organisms. Only small quantities of alcohol were encountered in
the leachates with no detectable aldehydes or esters. The
quantity of organic materials being leached as determined by
these leaching tests was considered very low, and their
anticipated environmental impact is negligible.
Toxicity Tests
Since the landfill selected to receive the waste had a leachate
collection system which directed the collected leachates to the
municipal sewer system, an attempt was made by means of
toxicity tests to assess the impact of disposal of the material in
the landfill upon the wastewater treatment plant organisms.
Thus, toxicity tests were conducted utilizing nonacclimated
activated sludge type organisms. Results are included in Table
111. The results indicate that no dieoff occurs from direct contact
of the sludge with the bacterial organisms. The second industrial
residual indicates an actual increase in the number of organisms
present as a result of contact with the wastewater residual. In
actual practice, the wastewater treatment plant organisms
would become acclimated to the leachate obtained from the
landfill, since this would represent a continuously flowing,
wastewater source.
Impact on Groundwater
The environmental impact of the disposal of the wastewater
residuals on the groundwater was estimated on the basis of soils
known to be present at the landfill location and by a study of the
attenuative properties of these soils. The data was used to
predict the probable leaching which would result from the
codisposal of this material with municipal solid waste and the
attenuation of metallic ions which would occur in the soil.
Table 1 indicates that several metallic ions were present in
substantial quantities, but that a negligible amount of the
chromium present was in the hexavalent form. Therefore,
migration of the chromium through the landfill and the soil
should be negligible. Recent Federal EPA research efforts2 in
the area of co-disposal of industrial waste with municipal solid
waste has shown that no additional leaching of metallic ions
results from the co-disposal of many industrial sludges with
municipal solid waste. The initial rate of leaching is higher only
when the ion of interest is present in an already soluble form,
therefore amenable to immediate transport in an aqueous phase
rather than having to be solubilized by the organic acids pro-
duced within a landfill environment. This is found to hold true
for the metallic ions investigated, as well as nutrient and organic
parameters. Thus, the disposal of these wastewater residuals in
municipal solid waste landfill would not, on a basis of recent
EPA research data, cause increased leaching of metallic ions.
Leachate is produced within a landfill and this leachate must
migrate through the soil before entering any groundwater unless
impermeable barriers are employed to collect the leachate. Dr.
Robert Griffin3 has recently shown that heavy metaJ removal
from the leachates by various clay materials is a direct function
of pH. The data indicates that removal of heavy metal cations
from landfill leachate generally increases with increasing pH
value and with increasing concentration of the metallic ion in
solution. For such parameters as trivalent Chromium, Copper,
Zinc and Cadmium, a sharp rise in removal is noted in the pH
range of 5 to 7, which is a general pH range for landfill leachates.
The results of this study as well as other supporting studies4 for
Lead, trivalent Chromium, Copper, Zinc, and Cadmium have
led to the conclusion that removal of heavy metals from strong
acid solutions by clay minerals is primarily an exchange-
absorption reaction which is affected by ionic competition. If
the pH is raised, adsorption is increased due to reduced
competition from hydrogen ions and formation of a series of
hydroxyl comple ions of lower valance. Finally, initiation of
precipitation occurs in the pH range of 5 to 7, and precipitation
becomes a major removal mechanism in a neutral or alkaline pH
range. Removal percentages for these metallic ions in the pH
range of 5 to 7 have always been greater than 80%. Additional
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150 Environmental Assessment
Table III—Toxicological Results
30 Minutes
24 hours
48 hours
96 hours
0
1.7 x 106
2.5 x 106
6
6.8 x 10
6.5 x 106
0.1
2.1 x 106
2.5 x 10
4.5 x 106
7.2 x 106
0.3
6
3.1 x 10
, 6
3.5 x 10
8.9 x 106
1.1 x 107
0.5
6
2.5 x 10
4.0 x 10
1.5 x 107
2.3 x 107
1.0
3.8 x 106
3.5 x 106
1.2 x 107
2.2 x 107
studies by Korte5 indicate that materials of the silty clay loam
type, such as Chalmers or Fairmount soil adsorb trace elements
such as Arsenic, Cadmium, Chromium, Copper, Mercury,
Nickel, Lead and Zinc quite well, and that resolubilization of
these adsorbed elements by acidic and aqueous solutions is
extremely low. It should be noted that Chalmers or Fairmount
soil having a composition of 7% sand, 58% silt and 35% clay and
a cation exchange capacity of about 26 millequivalents per 100
grams was found at the base of the landfill selected to receive the
waste. The predominant clay material in this type soil is
montmorillonite. From the above discussion it was apparent
that migration of significant quantities of heavy metals would
not occur as a result of co-disposal of the industrial residuals
with municipal solid waste, and if significant metal contamina-
tion did occur in the leachate, attenuation of the metals by the
soil present on site would occur.
It should be noted that leachate produced within the landfill
will be collected by an underdrainage system and routed to an
interceptor sewer. This will also prevent leachate from migrating
through the clay or soil liner, and entering the groundwater. In
addition, monitoring wells have been located at this landfill site
to detect any possible contamination of the groundwater. To
date, no contamination of this groundwater has been detected.
In summary, we indicated that no effect on the groundwater in
the vicinity of the landfill would occur due to the disposal of
these materials.
Operational Plan
An operational plan indicating how we were to remove,
transport and dispose of the wastewater residuals was developed
and submitted with the environmental impact statement. Two
methods can be employed to remove materials of this type. The
first of these involves the use of a dragline or clamshell to remove
the material and deposit it in dump trucks for transport. This is a
relatively slow, tedious process involving the use of more
expensive equipment and in this particular case requires a boom
on the dragline of at least 110 feet. Additional problems
associated with the removal of material by this method were the
lack of access roads sufficient for the heavy trucking and
movement of the dragline itself. The slopes immediately
adjacent to the lagoon were such that movement would be re-
stricted.
The method selected for removal of the sludge was by front-
end loader. This involved excavation ol a trench to the base of
the lagoon and removal of the sludge by the front-end loader.
This method works reasonably well providing the base of the
lagoon is sufficiently firm to support the weight of the loader.
Nevertheless, even with a firm clay base, ruts were formed in the
base of the lagoon which makes removal more difficult. The
placement of large (l-'/2 to 2 inch) aggregate at the base of the
lagoon was necessary in order to complete the effort by this
method.
The winter of 1977 was one of the worst on record and
excavation efforts were severely hampered by the extreme cold
and snow. As a result of the weather the time involved for
completion was twice that originally anticipated, We have not
yet begun the second disposal effort; and, 1 cannot report to you
the problems encountered with sludge removal on the other
lagoon.
REFERENCES
1. Fenn, I). G., K. J. Hanley and T. V. DeGeare, "Use of the
Water Balance Method for Predicting Leachate Generation
from Solid Waste Disposal Sites", EPA Publication SW-
168, (1975).
2. Streng, D. R., "The Effects of Industrial Sludges on Landfill
Leachate and Gas", presented at National Conference on
Disposal of Residues on Land, St. Louis, Mo., (1976),
3. Griffin, R. A., "Effects of pH on Removal of Heavy Metals
from Leachates by Clay Minerals", presented at the U.S.
EPA Hazardous Waste Research Symposium, Tuscon,
Arizona, (1976).
4. Griffin, E. A. and M. F. Shimp, "Attenuation of Pollutants
in Municipal Landfill Leachates by Clay Minerals", Final
Report for U.S. EPA Contract 68-03-0211.
5. Korte, N. E., et al., "Trace Element Migration in Soils:
Desorption of Attenuated Ions and Effects of Solution
Flux", presented at the U.S. EPA Conference on Hazardous
Wastes, (1976).
-------
Land Disposal of Acidic
Basic and Salty Wastes
From Industries
Dhiraj Pal, M. R. Overcash,
and P. W. Westerman
North Carolina State University,
Raleigh, North Carolina
INTRODUCTION
Industrial wastewater management by use of land application
(LA) technology has been envisioned as an alternative for a long
time. Some industries, e.g., canning factories, milk plants and
packing plants have actually used this alternative with little or
no pretreatment design for the removal of certain constituents
which when applied at excessive levels may upset the soil-plant
system. Lack of adequate design criteria in LA systems coupled
with asystematic attempts on (i) the understanding of the
prohibitive constituents in wastewater (ii) the acceptance level of
various wastewater constituents in the soil-plant system and (iii)
the fate of various constituents of industrial wastes in soil eco-
system under varying environmental conditions, restricted the
development of LA technology. In fact, many of these systems
have not performed as well as expected.
Our research aims at developing an integrated computer
program designed to model industrial waste constituents. It is
applicable to any wastewater for identification of levels at which
a waste constituent becomes land limiting because of the eco-
nomic reasons and requires a limited pretreatment of the
wastewater for removal or reduction of toxic effects in order to
economically (least cost) dispose on land.
The industrial wastewater constituents so far considered
include (i) acids (ii) bases (iii) heavy metals (iv) nutrients (v) oils
(vi) volatile organics (vii) salts (viii) toxic anions and (ix) water.
In present paper we shall deal only with 3 classes of
constituents- acid, base and salts—which are being often ap-
plied to the soil systems without adequate recognition of their
potential impacts in long run.
The rates at which acids, bases and salts can be loaded on land
is dependent on (a) soil characteristics such as (i) soil reaction-
acid, base or neutral, (ii) soil cation exchange capacity, (iii) soil
base saturation and balance of ions, (iv) soil salt level and
electrical conductivity and, (v) rate of loss of organic and
inorganic acids, bases and salts by microbial transformations,
plant uptake, degradation and movement by leaching/ runoff;
(b) waste characteristics such as concentration and total load of
problem constituents, their biodegradability, movement and
accumulation; (c) crop tolerance level of waste constituents; (d)
climatologic and geologic variables that impose constraints on
above factors; and lastly but not the least (e) management and
economic factors that go into design and operation of industrial
waste land application systems. Parameters listed above deter-
mine the rate at which soils can assimilate the acids/bases/salts
which must be managed such that these do not accumulate in the
amounts injurious to crop production. And hence a knowledge
of soil-plant fundamentals is essential to the study and design of
land based receiver systems. Before discussing the interactions
and fate of individual waste constituents in soil-plant system, a
brief review of some important terms and definitions is given.
Terminology and Definitions
General
Electrical conductivity (EC) is defined as the reciprocal of
electrical resistivity, r experienced during flow of current
through an aqueous solution when 2 parallel electrodes are
immersed in it. Symbolically,
1
EC - r =
1
ohms cm
mhos
cm
EC has been directly correlated to salt content and osmotic
pressure.
Salt concentration, ppm = 651 x EC in mmhos cm-1
Osmotic pressure, atm = 0.36 * EC in mmhos cm-1
Electrical conductivity is measured by use of pipet type
conductivity cell with platinized platinum electrode attached to
a Wheatstone bridge. These are commercially available with
operation manual or manufacturer's instructions. Solutions or
saturation extracts of soil can be used directly on the conductiv-
ity bridge after appropriate calibrations. Like irrigation waters,
wastewaters may be categorized based on EC.
EC (wastewater) Category
pmhos/cm at 25 C
< 250
250 - 750
750 - 2250
Low Salinity
Medium Salinity
High Salinity
>2250 Very high salinity
Based on EC of soil saturation extract, soils are classified as
follows.
mmhos/cm at 25 C
<2 Low salinity, Normal and acid soils
2-4 Medium salinity, Average and near
neutral soils
151
-------
152 Basic and Salty Wastes
>4 Excess salinity, Saline and saline
sodic soils
pH is defined as the negative logarithm (to the base 10) of the
hydrogen ion concentration, H+, in a solution. Symbolically,
1
pH = -log10 H+ = log —
The pH indicates the degree of active acidity or active alkalinity
of the system and does not measures the total or potential
acidity/ basicity. The pH is inversely related to the hydrogen ion
concentration, that is:
H+ = 10TH
Commercial pH meters are available in the market. The pH of
aqueous solutions and wastewaters is accurately measured by
placing the glass and reference electrode assembly in the
solution and recording the potential difference developed due to
H+ across the glass membrane. Soil pH is usually measured in
1:1, soil, water suspension; 1:2 soil: 0.01 N CaCh solution; or 1:2,
soil; IN K.C1 solution. ThepH of 7 is considered neutral, <7 acid
and >7 alkaline or basic.
Sodium Adsorption Ratio (SAR) is defined as a ratio of the
me/1 of sodium ion in a wastewater or solution to the square
root of half the me/1 of calcium plus magnesium in the same
wastewater or solution. Symbolically,
Na+
SAR =
Ca++ + Mg"4-1"
Na+, Ca"1"*' and Mg++ must be expressed in units of me/1. In case
of soils, SAR is based on determinations of Na+, Ca++ and
Mg++ in the saturation extract with units of me/1 of saturation
extract. This is an important parameter in determining the
quality of irrigation water with respect to potential sodium
hazard. Based on SAR values, the wastewaters can be catego-
rized in 4 classes with respect to possible sodium hazard.
SAB value Sodium hazard to soil-plant
system
<10 Low
10-18
18-26
>26
Medium
High
Very high
For acid soils of Southeast region, these SAR values may be
conservative and perhaps wastewater with SAR value of 15
would be considered low sodium wastewater. Wastewaters with
SAR value greater than 15 must be amended with Ca and Mg
compounds to lower SAR value sufficiently below 15.
Acidic wastewater is one that carry such organic and/or
inorganic constituents which can donate proton(s) and that
measure a hydrogen ion concentration, H+, greater than 10"7 M.
The H+ of some industrial wastewaters may be as high as 10"1 to
10-i m.
Basic wastewaters usually carry H+ less than 10"7 M and may
be as low as 10-8 to 10"'1 M. The constituents of such wastewater
readily accept protons to form water from excess hydroxyl
groups, OH".
Salty wastes, e.g., saline wastewaters are those which contain
salts, i.e. reaction products of an acid and base. Based on their
salt content the saline wastewaters have been classified into 4
categories (i) low salinity with salt content less than 175 ppm(ii)
medium salinity with salt content greater than 175 ppm but less
than 525 ppm (iii) high salinity with salt content greater than 525
ppm but less than 160(1 ppm and (iv) very high salinity with salt
content greater than 1600 ppm. The most commonly occurring
salts are chlorides, sulfates, bicarbonates, carbonates and
nitrates of calcium, magnesium, sodium and potassium.
Waste constituents generated by an industry are family of
unwanted "non-economic" compounds discharged during
manufacturing process of useful products and can be expressed
in units of mass of waste per unit time and per unit of product
processed or manufactured, e.g. milliequivalents(me)acid day-'
gallon"1 wine manufactured, pounds salts day-1 thousand-1
chicken processed etc.
Land and Soil- Plant Fundamentals
Acid soils are those with a pH value less than 7.0 in 1:1 soil;
water suspension. For most practical purposes, the soil pH value
must be <6.5 to be sure of a pre ponderance of hydrogen ions
and probably of aluminum in proportion to hydroxyl ions.
Aggregate is a cluster of soil particles, such as ped, crumb or
granule, in size smaller than 5 mm. Water stable aggregates refer
to those clusters which can withstand the shear forces of water
and remain intact when subjected to rain drop impact.
Base saturation (BS) refers to as the extent to which the
adsorption complex of a soil is saturated with exchangeable
cations other than hydrogen. It is usually expressed as a per-
centage of the total cation-exchange capacity. In practice% BS
is calculated as follows
X Ca + X Mg + X Na + XK
where
% BS ="
CEC
X stands for exchangeable and units of exchangeable ions are
expressed in me/100 g soil. CEC denotes cation exchange
capacity of soil in me/100 g soil. Percent base saturation has
been found directly related to soil pH.
Buffering capacity of soils is the ability of the system to resist a
large change in pH upon addition of small amounts of acid or
base. Buffered systems do change in pH upon addition of acids
or base but the change is much less than that would occur if no
buffer were present. The amount of change depends on the
strength of the buffer or buffering capacity of the system. Soils
usually resemble "acidic" buffer where presence of weak acids
(humic, fulvic, aluminosilicic) and salts of weak acid (conjugate
base) exert considerable buffering action.
Calcareous soil is the soil containing sufficient limestone to
effervesce visibly when treated with cold 0.1 N hydrochloric
acid.
Cation exchange capacity (CEC) refers to as the sum total of
exchangeable cations that a soil can adsorb. It is expressed in
units of me per 100 g soil and is also called as "cation adsorption
capacity;, total exchange capacity or base exchange capacity.
Clay refers to all soil particles <2/a in diameter. The amount
of clay fraction in a soil is important in its textural classification
and influences many physical, chemical and biological proper-
ties of the soil system.
Exchangeable sodium percentage (ESP) is the extent in% to
which the adsorption complex of a soil is occupied by sodium.
Symbolically,
(Exchangeable Na in me/100 g soil) 100
pop s ——
CEC me/lOOg soil
Land refers to a two-dimensional surface of the earth
lithosphere, i.e. terrestrial area under various uses such as
cultivation, recreation, wildlife, urban development, rural
housing, municipal waste dumping, etc. Land has been classified
into various categories based on its suitability for a particular
-------
Basic and Salty Wastes 153
purpose and is usually measured in units of ft2, yd2, acre or
hectare area.
Land Application Technology (LAT) is a multidisciplinary
science dealing with the design aspects of and systematic study
of available waste materials for disposal on land as valuable
amendments in an environmentally acceptable, economically
attractive and aesthetic manner. This area of land use involves
efforts of environmental engineers, industrial and urban
planners, land developers, soil scientists, hydrologists and
economists.
iMndlimiting constituent (LLC) is determined from the ratio
of waste generation to waste assimilatory capability of soils.
This ratio for each waste constituent is the area of land or vol-
ume of the soil system per unit mass of waste constituent. The
constituent or family of constituents requiring the most area or
volume is identified as the LLC.
Saline soil refers to a non-alkali soil containing sufficient
soluble salts to impair its productivity. The electrical conductiv-
ity of the saturation extract of a soil must exceed 4 mmhos/cm at
25°C in order to be classified as saline.
Saline-alkali soil refers to a soil containing sufficient ex-
changeable sodium to interfere with the growth of most crop
plants and containing appreciable quantities of soluble salts.
The saline-sodic soils usually show the ESP >15, EC of the
saturation extract >4 mmhos/cm at 25°C and pH near 8.5 or
less in the saturated soil.
Sesquioxides are the oxides of iron and aluminum, Fe20 i plus
AhOi, found in soils in varying amounts.
Sodic soil refers to a soil that contains sufficient sodium to
interfere with the growth of most crop plants. The ESP is usually
> 15, EC of saturation extract <4 mmhos/cm at 25°C and pH
of the saturation paste usually >8.5.
Soil is a 3-dimensional (area * depth = volume) unconsoli-
dated mass on the surface of the earth that serves a natural
medium for the growth of terrestrial life such as plants,
microorganisms etc. Soil consists of mineral materials, organic
matter, water and air in varying proportions influenced by
genetic and environmental factors of: parent material (rocks),
climate (precipitation, temperature, etc.), macro- and micro-
organisms (flora, fauna, vegetation and higher animals), topo-
graphy (relief—slope) and time. Soil differs from the material
from which it is derived in many physical, chemical and
biological characteristics. Soil is measured in units of either
mass, e.g., top 6" of surface soil taken as 2 million pounds, or
volume, e.g., 6 acre-inch, 15 ha-cm.
Soil organic matter is the organic fraction of the soil including
plant and animal residues at various stages of decomposition,
cells and tissues of microorganisms and substances synthesized
by the soil micropopulation. It is usually determined on soils
which have been sieved through a 2 mm sieve.
Soil texture refers to the relative proportion of various size
groups of soil mineral particles. The various size groups are also
known as soil separates and include: gravel >2 mm, coarse sand
2-0.2 mm, fine sand 0.2 mm-20/i., silt 20-2ju , and clay < 2ft.
Based on percent of different soil separates, soils have been
classified into textural classes as sandy loam, loam, clay loam,
loamy clay, etc,
Soil structure indicates the combination or arrangement of
primary soil particles into secondary particles, units or peds.
The secondary units are characterized and classified on the basis
of size, shape and degree of distinctness into classes, types and
grades, respectively. Soil structure classes include grouping on
the basis of size, e.g. very thin, thin, medium, thick and very
thick. Soil structure types are based on the shape of aggregates,
e.g., platy, prismatic, columnar, blocky, granular, crumb, etc.
Soil structure grades are designated from 0 to 3 based on the
stability of aggregates within the profile. The grades are: 0)
structureless; 1) weak; 2) moderate; and 3) strong.
Waste assimilatory capability of soils is expressed as mass of
waste material per unit time per unit volume of soil (or unit area
of land) by which a constituent or family of constituents is
stabilized, separated or converted in an environmentally accept-
able manner. The important factor is a particular site chosen
and prevalent climatologic, geologic and other variables that
influence the metabolism and persistence of the waste constitu-
ent^) in question.
Table I: Industrial Categories Generating Acidic Waste Constit-
uents.
INDUSTRIAL CATEGORIES
- (ACID WASTE pH)
ORGANIC
INORGANIC
Winery Stlllage (3.5-5)
Mineral Acid Manufacture (3-4)
Paper and Pulp (4-6)
Dredge Mines (2-4)
Organic Acid Manufacture (3-6)
Coal Processing (3-5)
Dairy Operations (4-7)
Oil Refining (4-6)
Fermentation (3-5)
Petrochemical Manufacture (4-6)
Citrus and Orange Processing (4.2)
Metal Plating (2-4)
Leather Processing (5-6)
Steel Cleaning (3-5)
Tomato Processing (4-6)
Phosphate Fertilizer Manufacture (4-6)
Rubber Stores (4-5)
Naval Stores (3-5)
ACID WASTE GENERATION
- mllliequlvalents
acid present in waste
per unit of material processed or
product manufactured
ACIDIC CONSTITUENTS
ORGANIC ACIDS - Acetic, lactic, citric, uric,
etc
(weak)
MINERAL ACIDS - Hydrochloric, nitric, sulfuric,
hydroiodic (strong)
Acid Wastewater—Soil Interaction
Free acids in the industrial wastewaters (Table l)when put on
land would rapidly react with alkaline components of the soil
system and form salts with precedence of neutralization reac-
tions. Inorganic acids in the wastewater dissociate to a greater
extent than organic acids. And therefore, wastewaters carrying
inorganic acids would react much more rapidly than organic
acid waste constituents which would increase the buffering
capacity of the soil system. Organic acids are subject to
microbial utilization and degradation to carbon dioxide and
water. And thus the influence of organic acid components on
soil-plant system may be stimulation of the micropopulation in
the soil system and thereby increased consumption of oxygen
and a more rapid decomposition of soil organic matter. Organic
acid decay would tend to ameliorate soil physical conditions by
increasing the number and stability of soil aggregates and by
improving the structure. Continuous application of acid waste-
waters on soils may exert a "washing effect" where cations and
salts from soil are leached down, and thereby, decreasing salt
concentration of the soil solution over a long period of time.
Consequently, the soil may become deficient in bases and % base
saturation may decrease. This occurrence would certainly be
associated with a decrease in soil pH dependent on the buffering
capacity of total wastewater—soil system.
Anderson et al.1 working with citrus wastewater at Corona,
California found that the pH of percolating wastewater
increased from 5 to 7 with top foot of a well-buffered (calcare-
ous) soil, whereas the alkalinity, EC and Ca level of the waste-
-------
154 Basic and Salty Wastes
water increased with percolating depth. This could have been by
adsorption and use of H+ in exchange of Ca and other salt ions
displaced.
Palazzo11 used lime to raise the pH of an acidic (pH 3) dredge
soil of Delaware amended with sewage sludge. Application of
lime and sewage-sludge to the infertile acidic soil also increased
the cation exchange capacity and plant available phosphorus,
calcium and magnesium while exchangeable sodium and
potassium remained similar to control checks. He recom-
mended deeper incorporation of liming materials like CaO or
Ca(OHh to increase soil pH and plant available phosphorus.
Schroeder et al." in Davis, California found that pomace
stillage with pH of 3.5 to 5 and acidity of 1200 3800 mg Ca
COi/2 could best be disposed by land application at 100,000
gallons/acre/wk. Furrows were filled and a period was allowed
for evaporation and percolation prior to soil disking. They
encountered no problem of nuisance and speculated no salt
leaching to ground water within few years of study. They
suggested tile drainage as a solution to salt transmission
problem if a threat to groundwater was expected or shown.
If there are carbonates in the system such as in calcareous and
sodic soils, the carbon dioxide may evolve as follows:
acid
(i)COj + H+ ^HC03
reaction
acid
(ii) HCO"3 + H+ C02 + HOH
reaction
Thus mineral acid wastes are likely to decrease the buffering
capacity of the total system and may increase the solubilization
of CaC03 present in calcareous soils or can accentuate the lime
requirement of many acid soils in the Southeast but may
improve lime effectiveness by improved solubility of limestone.
Acid wastewaters can be used for reclamation of saline-sodic
soils in California and in improving the productivity of calcare-
ous soils of arid regions and flood plains. A correction in
alkaline soil pH by acid waste waters is bound to improve the
availability of nitrogen, sulfur and phosphorus in the soil-plant
systems. Continuous irrigation of a soil with acid wastewater
may influence the pH dependent charges of the clay-complex i.e.
decrease the cation exchange capacity and increase the anion
exchange capacity to a certain extent over a long period of time.
The pH of the soil-waste water system is also related to the
availability, solubility and immobility of plant nutrients and
toxic metals. For example, solubilities of complexed cations
Table II: Acid Tolera
such as Cu and Zn increase as the pH decreases. The solubilities
of Fe, Al, Mn and Ca phosphates are markedly pH dependent.
Water soluble Al in soils increases rapidly as the soil pH
decreases below 5. The solubilities and toxicities of aluminum,
manganese nickel and boron are high under acid conditions.
Soil-wastewater pH also determine the direction and rate of
redox reactions which are in part biologically controlled. Under
acid condition, iron, manganese and copper, are easily reduced
to more soluble forms and there exists greater potential for
nitrate reduction to N2 and N2O. The biological reduction of
nitrates and sulfates is associated with production of OFI- and
thereby an increase in pH may be evident.
Application of acid reaction wastes in soils promotes growth
of microorganisms requiring low pH. In highly acid environ-
ments fungi thrive better than bacteria. Certain microorganisms
are very specific with respect to their pH requirement. For ex-
ample, an actionomycetes causing potato scab does not grow
below pH 5.5 and damping off disease in nurseries can be
controlled by maintaining acid conditions at pH 5.5 or less. Acid
wastewaters for such situations would prove very beneficial
fungicides. Conversely, high acidity has been shown to retard
the activity of earthworms and nitrifying organisms. A decrease
in pH of alkaline soil by irrigation with acid wastewater would
promote microbial growth engaged in mineralization of nutrient
elements, enhance root growth and increase crop production.
At extreme pH values such as below 4.5, the vegetation
growth in soil-wastewater system is adversely affected. A study
of the acid mine wash contamination of soil revealed that a
decrease in pH produced toxic conditions detrimental to plant
growth (Blevins et al.2). High concentrations of A1+3 accounted
for much of this soil acidity is considered one major limiting
factor in plant growth. Acidity due to A1+3 could be neutralized
by application of lime and phosphates. Phosphorus applied in
the presence of lime on an acid soil results in production of
significantly higher yields of reed canary grass (Pal et al.10) than
when either lime or phosphorus are applied alone. There is
plenty of evidence in literature on (i) decreased availability of
certain nutrients, e.g., N, P, S, K, Mo, etc at pH value below 5.0
and (ii) increased availability and toxicity of certain metal
elements, e.g. Mn, Al, Cu, Zn, B, etc below pH 5.0.
Certain crop plants require highly acid environment for their
optimum growth. For example blueberries and cranberries
grow best between pH 4 and 5.0 and there are several other eco-
nomic crop species that require slightly acid environment for
their best growth (Table 11).
of Crops (Optimum pH).
Slightly Acid Tolerant Acid Loving Plants
(most tolerance)
Acid sensitive
(least tolerance)
1. Alfalfa (6.5-8)
Barley (6.5 - 8)
2. Peas (6.5-7.5)
3. Red clovers (6.5-7.5)
4. Red beets (6.5-8)
5. Rhodes grass (7-8)
6. Salt grass (7.5-9.5)
7. Sugar beets (6.5-8)
8. Sweet clover (6.5-8)
9. White clover (7.5-8)
10. Wild mustard (7.5-8)
Apple (5-6.5)
Balsam Fir (5-6)
Beech (5-6.7)
Bent Beans (6—7)
Bluegrass (5.206.5)
Boysenberry (5-6.5)
Corn (5.5-7)
Field bean (6-7.5)
Flax (5-7)
Hemlock (5-6)
Heather (4.5-6)
Holly, American (5-6)
Larch (5-6.5)
Lupine (5.5-6.5)
Magnolia (5-6)
Oat (5.5-7)
Peanut (5.3-6.6)
Phlox (5-6)
Pineapple (5-6)
Potatoes (4.8-6.5)
Red clover (5.7-7)
Strawberry
Tobacco (5.3-6.5)
White oak (5-6.5)
White clover (5.7-7.0)
Soybean (6-7)
Wheat (5.5-7.0)
Aspen (3.8-5.5)
Birch (4.5-6.0)
Blueberries (4-5)
Camellias (5-6)
Cedar (4.5-5.0)
Club moss (4.5-5)
Cranberries (4-5)
Irish potatoes (4-5.5)
Jack pine (4.5-5)
Milkweed (4-5)
Orchid (4-5)
Rhondondendron
(native) (4.5-6)
Shpagnum moss (3.5-5.0)
White & red pine
(4.5-6.0)
-------
Basic and Salty Wastes 155
Table 111: Industrial Categories Generating Basic or Alkaline
Waste Constituents.
INDUSTRIAL CATEGORIES - (BASIC WASTE pH)
ORGANIC INORGANIC
Photographic products (8-9.5) Ccuetie aod* .(10*13)
Laundry detergents, bleach, etc. (8-9) Textile (7.5 - 11.5)
Kraft mllla (7-9) Gas and coke works (8.5 - 10)
Soft drlnka (9-9.5)
Pickles manufacture (8-9)
Peach cannery waste (9.5 - 10,5)
Sea food processing (9 - 11)
ALKALINE WASTE GENERATION
- milliequivalents base present In waste
per unit of material processed or product
manufactured.
BASIC CONSTITUENTS
ORGANIC - Amides, amines, ammonium, proteinous, constituents
INORGANIC - Sodium hydroxide and carbonate, potassium
hydroxide, magnesium oxide, bicarbonate
hydroxide and carbonate, calcium bicarbonate
oxide, hydroxide and carbonate, etc
jk jk
0 OHa + OH- 6 OH + H.O
Y Y
1 i
positive OH" from lime neutral
charged oxide
oxide surface
surface (isoelectric
point)
water
jk
o OH + OH- ¦''•1""°""""'!
Y Y
k
O 0- + H.0
neutral OH" from lime negative water
oxide charged
surface oxide
surface
*5 7
o
E
o
^ 5
>-
>
H
O
3
O
z
o
o
o
<
(r.
Q
>-
X
LOAMY
SAND
0 10 20 30 40
EXCHANGEABLE - SODIUM - PERCENTAGE
Figure 1: Hydraulic Conductivity of a Clay Loam and Loamy
Sand as a Function of Exchangeable Sodium Percentage.
Adapted from Martin et al,8.
4 5 6 7
SOIL pH
Figure 2a: Deprotonation of Oxide Clay Surface and Devel-
opment of Negative Charge with Liming.
Figure 2b: Cation Exchange Capacity Versus pH of Few
California Soils. Adapted from Pratt et al,12.
-------
156 Basic and Salty Wastes
X
Q.
70
6.0
5 50
in
4.0
3.0
LOAMY
SAND
CLAY
LOAM
_L
25 50 75 100
PERCENT BASE SATURATION
Figure 3: Soil pH (1:1 Soil: Water Suspension) as a Function of
Percentage Base Saturation. After Overcash and Pal,9.
2 4 6 8 10 12 14 16 18 20 22
MILLIEQUIVALENTS OF BASE ADDED
PER 100 Q OF H - SATURATED SOIL
Figure 4: Titration Curves of Hydrogen-Saturated Soils With
Increasing Cation Exchange Capacity and Fineness of the
Texture. Higher Amount of Base was Required for Clay Loam
with High Cation Exchange and Buffering Capacity than for
Loamy Sand with Low Cation Exchange and Buffering Capac-
ity. Adapted from Foth and Turk,4.
Basic Wastewater—Soil Interaction:
Basic constituents in wastewater when applied to a land
would react with acid groups of the soil system resulting in the
formation of salts and complexes. Alkali wastes (Table III)
carrying caustic soda or other strong alkali base would instan-
taneously react with soil-plant system neutralizing the active
and reserve acidity of the receiver system, increasing the
exchangeable sodium percentage (ESP) and percent base
saturation, and raising the pH of the system. Application of
basic waste (pH 10.5 and NH3-N of 1120 ppm) to acid soils (pH
4.5-6.0) raised the soil pH in surface(4"-18") and did not affect
the subsoil pH (Brown,3). The increase in pH of surface soil was
by 1 or 2 units depending on rate of application.
By disposal of alkali wastewaters of a sugar beet cannery on a
soil in southern Ontario, Webber et at15 measured an increase in
exchangeable sodium from 2.5 to 8% of total exchangeable
cations. This increase in saturation ol exchange sites was
gradual and persistent indicating a sodium hazard by continu-
ous applications in long term. The build up ot alkali in soil may
lead to physical damage as manifested by low permeability,
decreased hydraulic conductivity (Figure 1) high runoff and
scanty vegetation. On sodic and saline-sodic soils, waterlogging
may occur and inadequate root aeration may prevail. Toxic
symptoms from excess sodium have been described by Lunt7.
Application of peach cannery wastewater (pH 10 and 72 ppm Ca
COi equivalent alkalinity) on a Cecil sandy clay loam soil, the
pH of the percolating water was reduced to less than 7.0 where
exchangeable ions like H+, Al+++ Ca++ and Mg++ were
displaced by Na+ due to mass action (Hanks et al5). Purification
of peach cannery wastewater by land disposal was found to be
highly effective and common Bermuda grass was found a
suitable cover crop where the irrigant is peach waste.
If the alkalinity of the basic wastewater is due to weak bases
such as ammonia, amines, calcium bicarbonate, lime, etc, it adds
to the buffering capacity of the system. Organic bases may
undergo biological decomposition and transformations with
production of ammonium, carbon dioxide and water.
Oxidation of basic ammonia to nitrate is associated with pro-
duction of protons or hydrogen ions, which may decrease the
pH of soil-waste system. Likewise, oxidation of sulfur and
carbon compounds may produce acids. Organic base
degradation may also improve soil physical conditions besides
increase in soil buffering capacity and exchange sites.
Irrigation of acid soils with alkaline reaction wastewaters may
decrease the solubility and toxicity of Al, Ni, Mn, Zn, Cu, B, etc.
Dominant cations in the alkaline wastewater displace other
cations of the exchange complex. An increase in pH is also
associated with increased cation exchange capacity (Figure 2)
and is perhaps the result of increased base saturation of the soil
(Figure 3) where as a rule an increase in pH dependent negative
charges of the clay and humus complexes occurs. With increas-
ing cation exchange capacity of soils, greater amounts of bases
are required to effect a given change in pH (Foth and Turk,4).
Data presented in Figure 4 establishes conclusively that soils of
high CEC exert considerably greater buffering action than soils
of low CEC. Microorganisms requiring high pH for their
optimum growth would tend to proliferate with the continuous
disposal of alkaline wastewaters on land under alkaline reaction
environment. Biological oxidation would be favored for Mn,
Cu, Fe and N compounds.
Application of basic wastewaters on the acid soils may correct
soil pH to neutrality, improve microbiological transformation
in favor of NO^ SOJ"and PO™release from organic matter
present in soil and wastes and may decrease the solubility and
toxicity of heavy metals already present. All these factors may
have a cumulative effect on better crop performance and yield of
the economic plant parts under acid soil regions.
Saline Waste water-Soil Interaction
Salts are present almost in all irrigation waters and salts of the
industrial wastewaters would behave in soils similar to that of
any irrigation water applied to land. In the context of saline-
wastewater (Table IV), we would consider only chloride, sulfate,
bicarbonate, nitrate etc salts of sodium, calcium, magnesium
and potassium. Criteria used in classification of irrigation
waters (on the basis of total salinity and quantity of sodium
present) are equally applicable to saline wastewater categoriza-
tion and use for soil-plant systems. Salinity interacts with soil
system by movement and accumulation of salts in the direction
of maximum water flow. To make this point clear, if the
evapotranspiration of a soil-plant system on an annual basis
exceeds the total water input by precipitation, irrigation and
other means it is expected that the probability of soils to become
salt-affected in the surface is very high unless considerable
-------
Basic and Salty Wastes 157
amounts of good quality water are applied to leach the salts
down the root zone. In regions where annual rainfall exceeds the
evapotranspiration and adequate drainage systems have been in
operation, no buildup of salts in the soil surface is expected.
Soluble cations and anions move with water as solute and salts
do concentrate at the site or surface of water evaporation.
Continuous land application of salty wastes could encourage the
buildup of salts in the surface or root zone as water is transpired
and evaporated from the surface. With prolonged application of
saline wastewater, the tendency is for acidic soils to be made
neutral or even alkaline as has been shown in application of
wastewater on extremely acid soils (Sopper,14).
Salty wastes would add to the electrical conductivity of the
soil system. In case the sodium salts exceed the Ca- and Mg-salts
in the wastewater with a high sodium adsorption ratio (SAR),
soil cation exchange capacity will become saturated with
exchangeable sodium. The exchangeable sodium percentage
(ES P) of a soil is related to the S A R of the soil saturation extract
by the following equation:
1.47 SAR - 1.26
ESPsoil ~ 0.0147 SAR+ 0.99
The excess Na in soils may induce deficiencies of calcium and
magnesium by removal or precipitation of exchangeable and
soluble Ca and Mg in the form of carbonates. Salt affected soils
have been arbitrarily classified based on the chemical conditions
as follows:
Soil Group
Other naraea
EC of saturation
extract
nmhos/cm at 25 C
ESP
*
PH
Saline
Solonchak
> 4
<15
<8.5
Saline-sodic
Saline-alkali, solonetz
> 4
>15
*8.5
Sodic
Alkali
< 4
>15
>8.5
The criteria employed to categorize the salt affected soils are
limited by the gradational and continuous nature of the
parameters considered with no sharp index to plant response
and soil physical behavior. Soils with high salt content are
flocculated, friable and permeable with high osmotic concentra-
tion of soil solution. If sodium happens to be the dominant ion
in the salty wastes and the SAR of wastewater is greater than 30,
the sodium dominates on the exchange micelle. Such soils with
high sodium salts eventually become saline-sodic. When the
salts are lost or removed by leaching and runoff, the sodic soils
become dispersed, deflocculated and impermeable with poor
tilth. In absence of salts, the hydrated monovalent sodium ion
undergo extensive hydrolysis and thereby production of OH"
which is responsible for increased repulsion among negatively
charged particles. In absence of salts, Na- soils are so much
dispersed and impermeable to water flow that the occurrence of
this phenomenon is referred to as freezing. Hydraulic conductiv-
ity of soils is highest under acid and neutral conditions but
decreases rapidly as the exchangeable sodium percentage (ESP)
exceeds 5%. At 10% and 15% exchangeable sodium, hydraulic
conductivity becomes 1/3 and 1/10, respectively, of the value
under normal and acid soil (Figure 1). Addition of salty wastes
may nullify the excessive negative charges and thereby decrease
the extent of dispersion. Di- and tri-valent salt cations are more
effective in nullifying the negative charges of the dispersed
colloids than are the monovalents. Potassium ion provides a
better fit with clay lattice geometrically than sodium ions and
does not undergo as extensive hydrolysis in absence of salts as
does sodium ion. As a result, K-soils are not dispersed as much
as Na-soils. The sodic soils can only be reclaimed by chemical
treatment with gypsum and by leaching of excessive Na with
plenty of water low in sodium and high in other basic salts. In
frozen sodic soils, use of high salt wastewaters may provide nec-
essary physical conditions for water movement by flocculating
the dispersed soil particles. High salt wastewaters raise the
osmotic pressure of soil solution, as a result the gradient of
osmotic potential between soil solution and root cells is lowered.
This results in less water uptake by plants in highly saline soil en-
vironments. The visible effects of excess salinity are reductions
in both rate of growth and total plant size. Forage and seed
yields are also usually reduced. With increasing salinity,
available water decreases and so does the plant growth. Salt
affected plants do not respond to applied fertilizers which
further add to osmotic potential of soil solution and thus
aggravating the salinity effects. Excessive salt buildup in soils by
consecutive disposal of saline wastes for many years may alter
the microbial population and activity. And thereby, influence
on the mineralization of carbon and nitrogen is expected as a
result of salty waste application onto lands. In regions of base
unsaturated soils such as acid soils of southeastern United
States, application of low sodium salty wastes may prove
beneficial amendment for improving percent base saturation,
decreasing exchange acidity and increasing nutrient supply.
Henry et al6 recorded about 30% increase in yield of reed canary
grass by application of a packing plant effluent (with SAR of
nearly 15) to a Miami silt loam and a peat soil when compared
with city water irrigation under similar conditions. The effluent
contained soluble salts of Kf, Ca++, Mg++, Na++ and NH4 as
NO,, and possibly C1-, S04 etc. The high additions of Na+ salts
initially may displace Ca++ and Mg++ from soil exchange
complex rendering them more available to growing crops during
the first few years while depleting soil fertility. On an annual
basis, crop plants take up more calcium and magnesium than
sodium (Table V). Soluble salts are taken up by mechanisms
similar to other plant nutrient elements through the routes and
translocated to the tops with water. Some plants have evolved
genetic characteristics to accumulate salts, others do not and few
even tend to exclude salts. Selection of salt tolerant crops (Table
VI) and varieties is important in management of soils amended
with high salt wastewaters.
CONCLUSIONS
Criteria employed in management of acid, basic and salty
wastes by soil incorporation or crop irrigation have been
discussed in cognizance of land limiting factors. In summary, we
propose the following considerations in design of acid, basic and
salty waste management by land applications systems:
1. Consider "Opposite Reaction Amendment Theory" which
states to place acidic waste on alkaline soil and basic waste on
acid soil. On base unsaturated acid and non-saline sodic soils,
application of salty waste may prove profitable.
2. Adjust sodium adsorption ratio of wastewater preferably
below 10 to eliminate any excessive Na accumulation on
exchange sites. This can easily be achieved by dissolving the salts
of Ca and Mg in the wastewater after appropriate calculations
for each wastewater. Critical limit for SAR of irrigation
wastewater is 15.
3. Know the cation exchange capacity, exchangeable cation per-
centage and percent base saturation of the soil system to arrive
at a loading rate of necessary amendment (such as gypsum and
lime) for soil and waste combined.
4. Reject wastewaters for continuous land application with EC
greater than 2000 n mhos/cm at 25° C unless (i) salts are
removed by desalting processes (ii) plenty of good water is
available to allow washing of accumulating sodium salts from
soils.
-------
158 Basic and Salty Wastes
Table IV: Industrial Categories Generating Salty Waste Con-
stituents
INDUSTRIAL CATEGORIES - (SALTY WASTE)
Perhaps all industries
Chilling wastes
Brines
Desalting waste
Detergents, soaps
Chicken Processing
EC Range
*—o-
< 500 ymmhos/cm to >10 mmhos/cm at 25 C
extremes > 30 mmhos/cm
SAR Range
<1 to >30, extremes >100
SALTY WASTE GENERATION
Kilograms salt in waste per unit of
material processed or product manu-
factured.
SALT CONSTITUENTS
Chlorides, sulfates, nitrates, carbonatesj
bicarbonates and phosphates of sodium,
potassium, calcium and magnesium.
Salts of fatty acids.
5. In long run, the continuous app]jcati ,
wastes may influence the groundwater uualitv Ami S'C y
considerations rami be given to exiaJ" '
q„,l,t» o(»ate,. Or„u„d»..Wqn,,i,y°^ne^^1= f
ultimatelydetemiine the "lite span" "f thesite dep^ndii^g onthe
evapotransptration, drainage condition and
region. Ui ine
Above considerations would prove to
importance in design of a computer program
industrial wastewaters containing organic and inorganic salts ol
acidic, basic or neutral reaction. 6 c saits ot
ACKNOWLEDGEMENTS:
^of.heU„i«„i,y„fNorthCrin:T^«^^;
in this publication does not imply endorsement bv the North
Carolina Agricultural Experiment Station, of the orod?Z
named nor criticism of ones not mentioned. "uucis
REFERENCES
1. Anderson, D.R., W.D. Bishop, H F 1 nrlwio d . •
of Citrus Wastes Through Soil. Proc.'of the 2htlMw!*
Waste Conf. 1966 Pt. 2, Purdue Univ., Lafayette
Engg. & Ext. Series #121. pp 892-901 1966 lndldna-
2. Blevins, R.L., H.H. Bailey and G.E. Ballard. The Effect nf
Acid Mine Water on Flood Plain Soils in the Western
Kentucky Coal Fields. Soil Sci. 110 )91 196 1970
Brown, K. W. An Investigation of the Feasibility'of S™.
Disposal of Waste Water for the Jefferson Chemkal r!
Conroe, Texas. Final Report Phase I, Texas A & m
Research Foundation. F.E. Box H, College Station, Tei!
3s. 1975. '
Foth, M.D. and L.M. Turk. Fundamentals of Soil
Fifth Edition. John Wiley & Sons, Inc. New York 1972
3.
Table V: Approximate Pounds of Salt Ions
Removed from the Soil Each Year by Various Crops in the El Paso Area.
Crop
Crop yield,
pounds per
acre
Sodium
Pounds removed by crops each acre
Calcium Magnesium Sulfate Chloride Total
Sweetclover
hay
Sudangrass hay
Alfalfa hay
Barley straw
Corn silage
Barley grain
Sorghum grain
Cottonseed
Average
8,000
17
156
104
69
33
379
10,000
21
34
69
199
67
390
8,000
42
60
49
52
55
258
14
8
3
28
15
68
2,000
30,000
72
58
103
97
103
433
/>
1
1
3
7
14
10,000
2
4,000
6
3
5
8
17
39
3
2
5
8
16
34
1,500
7,938
22
40
42
58
39
202
-------
Basic and Salty Wastes 159
Table VI: Salt Tolerance of Crops (Optimum pH)
I. Very Very Salt Tolerant
II. Moderately Salt Tolerant
III. Near-neutral pH
Requirements
(EC 8-12 mmho8/cm)
(EC 4-8 mmnos/cm)
(EC 2-4 nvmhos/cm)
Apricot (6-7)
Alfalfa (6.2-7.8)
African violet (6-7)
Spinach (7-7.5)
Arborvitae (6-7.5)
Alyssum (6-7.5)
Alfalfa (6.5-8)
Spinach (6-7.4)
Tobacco (5.5-7.5)
Asparagus (6-8)
Almond (6-7)
Sorghum (5.5-7.5)
Tamarack (5-6.5)
Barberry (6-7.5)
Barley (6.5-7.8)
Sycamore (6—7.5)
Bell pepper (6-7)
Bermooda grass (7-8)
Begonia (5.5-7.0)
Sunflow (6.5-8)
Black oak (6-7)
Burnish bush (5.5-7.5)
Broccoli (6-7)
Tomato (6.5-8)
Yam (6-7)
Cabbage (7-8)
Calendula (5.5-7.0)
Vetches (7-8.2)
Cherry (5.5-7)
Carnation (6-7.5)
Celery (5.8-7.0)
Wheat (6.5-8)
Douglas Fir (6-7)
Carrots (5.5-7.5)
Crab apple (6-7.5)
Zinnia (5.5-7.5)
Hot pepper (5.5-7)
Cauliflower (5.5-7.5)
Cotton (6.5-8)
Lantana (6-7)
Chrysanthemum (6.5-8)
Cowpeas (7-8.2)
Poinsettia (6-7)
Date Palm (7.5-8.2)
Corn (6.5-8)
Quince (6-7)
Garden beets (6-8)
Cucumber (6.5-8)
Rice (5-6.5)
Geranium (6-8)
Johnson grass (6.5-7.5)
Reed canary grass (5.5-7)
Ivy (6-8)
Lespedeza (7-8.2)
Rose (5-6.5)
Panic grass (7-8)
Lily (6-7)
Rye (5-7)
Peas (6-7.5)
Lilac (6.0-7.5)
Soybean (5.5-7.5)
Peach (6-7.5)
Maple (6-7.5)
Sesbania (5-7)
Purple sage (7-8)
Millet-sorghum (7-8.2)
Potato (5-6.5)
Rhodes grass (7-8.2)
Muskmellon (6.0-7.0)
Sweet potato (5-7)
Salt grass (7.5-8.2)
Rhubard (5.507.0)
Spinach (6-7.5)
Safflower (6.5-7.8)
Sugar beets (6.5-8.0)
Snap dragon (6-7.5)
Sugar cane (6-8)
Snowball (6.5-7.5)
Wild mustard (7-8)
Sweet William (6-7.5)
5. Hanks, F.J., J.R. Lambert and P.S. Opliger. Hydrologic
and Quality Effects of Disposal of Peach Cannery Waste.
Trans. Amer. Soc. Agric. Engg. 11:90-94. 1968.
6. Henry, C.D., R.E. Moldenhauer, L.E. Engelbest and E.
Troug. Sewage Effluent Disposal Through Crop Irrigation.
Sewage and Industrial Waste 26, Rt 1:123-133. 1954.
7. Lunt, O.R. Sodium. In. H. D. Chapman (ed.) Diagnostic
Criteria for Plants and Soils, Univ. of California, Div. of
Agric. Sci., pp. 409 -432.
8. Martin, J.P., S.J. Richards and P.F. Pratt. Relationship of
Exchangeable Sodium Percentage at Different Soil pH
Levels to Hydraulic Conductivity. Soil Sci. Soc. Amer.
Proc. 28:620-722. 1964.
9. Overcash, M.R. and D. Pal. Industrial Waste Land
Application. AIChE Today Series, New York. 1977.
10. Pal, D. and H.M. Reisenauer. Lime * Phosphorus Interac-
tion. Annual Meetings of the Western Soc. Soil Sci. UC,
Berkeley. 1970.
11. Palazzo, A.J. Reclamation of Acidic Dredge Soils with
Sewage Sludge and Lime. Corps of Enggs. U. S. Army
C.RR & E. Lab, Hanover, New Hampshire. 1976.
12. Pratt, P.F. and F.L. Blair. Cation Exchange Properties of
Some Acid Soils of California. Hilgardia 33:689-706. 1962.
13. Schroeder, E.D., D.J. Reardon, R. Mateoli and W.H.
Hovey. Biological Treatment of Winery Stillage In, Food
Processing Waste Management, Syracuse, N.Y. (Spon-
sored jointly by Cornell Univ. Nat. Waste Treat. Res. Prog.,
EPA and Nat. Can. Assoc.) pp. 8-19. 1973.
14. Sopper, W.E. A Decade of Experience in Land Disposal of
Municipal Wastewater. Proc. of the Symp. on Land Treat,
of Second Effluent. Univ. of Colorado, pp. 19-61. 1973.
15. Webber, L.R., T.G. Stevens and D.A. Tel. Exchange
Properties of a Soil Used for the Disposal of Alkali Cannery
Waste. Food Processing Waste Management, 1973. Syra-
cuse, N.Y. 1973.
16. Longenecker, D.E. and Lyerly, P.J. Control of Soluble
Salts in Farming and Gardening. The Texas Agric. Exp.
Sta. Bull. 876. Revised June 1974.
-------
The Combination of Flue-Gas
Desulfurization Sludges and
Municipal Waste to Produce
Fertile Soils
Robert W. Briggs, Robert C. Freas,
and Laszlo Pasztor
Dravo Lime Company
Pittsburgh, Pennsylvania
INTRODUCTION
This paper presents a summary of the findings and
conclusions of the first phase of a similarly titled project being
jointly funded by the U. S. Environmental Protection Agency,
EPA grant number R803999-I0-0, and Dravo Lime Company,
a wholly owned subsidiary of Dravo Corporation. Project
Officer for the EPA is Mr. William L. DePrater. Throughout
this phase of study Dr. Dale Baker, Pennsylvania State
University, has been actively involved as a consultant in soil
chemistry, and has contributed greatly to the success thus far
achieved. Chemical testing of municipal waste materials and
synthetic soils developed during this program were tested at the
Merkle Laboratories of Penn State University. All other
laboratory work was completed in the research facilities of
Dravo Corporation.
Man's interaction with his environment is becoming of
increasing concern as the volume of waste materials produced
continues to multiply. Two of these waste products, flue gas
desulfurization sludges and municipal sludges present particu-
larly challenging problems because of their poor engineering
and disposal properties and the immense quantities of materials
generated. Thus, the question arises, do these sludges have
mutually compatible characteristics which would permit their
common disposal in a useful application?
Flue-gas desulfurization sludges consist primarily of calcium
sulfate and calcium sulfite salts, along with varying amounts of
fly ash and unused scrubbing reagents. The engineering proper-
ties of these sludges are very poor as they have a paste-like
consistency, low sheer strength and bearing capacity and are
thixotropic. The chemistry of the aqueous phase varies, depend-
ing upon the soluble and volatile components of the coal, the
scrubbing process chemistry, evaporation and other concentra-
tion effects during scrubbing and settling.
The ability of scrubber sludges to support plant growth is
somewhat similar to that of fly ash dumps as reported by
Pasztor, Selmeczi, and Labovitz.1 While the quantities of some
elements are in excess and have a toxic effect, there is a lack of
other elements, and particularly nutrients, in sufficient quantity
to support growth. Studies with fly ash as well as preliminary
investigations with FGD sludges indicate that selected hardy
varieties of plants grow rather well, but require frequent
fertilization in order to support sustained growth. However,
both fly ash and scrubber sludges are void of materials which
can either supply or store the more important fertilizer compo-
nents. Further, chemical analysis of the sludge indicates that
while there may be a sufficient amount of calcium available, the
sludge does not possess cation exchange properties and,
therefore, is not capable of retaining ammonium and potassium
ions. Tables 1 and II present typical chemical analysis for the
FGD sludges and municipal waste used in this study.
Municipal sludge is the product of municipal sewage treat-
ment. Methods of disposal have included a wide variety of
approaches ranging from incineration to landfill disposal. Sev-
eral universities and municipalities have experimented with
spray irrigation, but have not attained the degree of success
generally hoped for. Thus, it was felt that the mutual disposal of
the municipal sludges with some other waste product might lead
to improved disposal techniques and the development of a fertile
material.
TABLE I: Chemistry of Flue Gas Desulfurization Sludges
(Thickener Underflow)
Weight % on dry basis
except pH and % Solids
P Group
(High Ca)
M Group
(Ca-Mg)
PH
9.2
10.7
Si02
30 .9
24.1
R2°3
23.3
24 .9
CaO
16 .3
22.0
MgO
0.5
1.1
Al2°3
16.1
12.9
Fe2°3
7.4
10.7
so2
9.0
17.7
so3
6.8
2.1
S-Total
7.2
9.7
O
O
INJ
1.7
3.2
C-Pree
8.8
3.3
C-Total
9.3
4.1
Free Base (as CaO)
0.6
0.6
% Solids
34.6
30.2
-------
Flue-Gas Desulfurization 161
TABLE II: Chemistry of Municipal Waste Treatment Sludges
ppm on Dry
except pH
Weight Basis
and % Solids
Municipal A
Filter Cake
Municipal E
Filter Cake
pH
12 .50
8.30
K
2119
3326
Ca
136433
26099
Mg
805B3
4463
Zn
448
2159
Cu
386
866
Mn
1048
510
Fe
18706
18930
A1
9104
17032
Cd
1
98
Cr
98
510
Pb
129
788
Ni
71
67
Co
36
29
Na
900
1014
no3~n
955
2198
nh4-n
890
16092
Org-N
14063
22749
Total-N
15908
41039
Total-P
10405
15646
% Solids
22.6
21.0
Project Objective
The basic objective has been to determine the optimum
conditions under which flue gas desulfurization sludges,
obtained from operational sulphur dioxide scrubber systems,
could be stabilized and combined with municipal sludges to pro-
duce a fertile soil. In order to accomplish this objective, the
scrubber sludges selected for this study were treated with a
stabilizing agent which has been used successfully on a full scale
operational basis, and for which technical data was readily
available.
In the final analysis it was the intention of this study to pro-
duce a useful material from two waste products, by simple
mixing and stabilization, which with little or no additional
fertilization would sustain plant growth on a permanent basis.
Thus, this investigation consists of two phases.
Phase 1, being reported on here, included the bench scale
stabilization, testing of the sludge mixtures, and indoor plant
growth tests. Phase II, which is presently being started includes
outdoor test plot trials utilizing the best synthetic soils devel-
oped in Phase I.
Phase I of the investigation followed a series of steps similar to
those shown in Figure 1. These steps provided a systematic
approach by which well over 200 sample mixes could be evalu-
ated, and a selection could be made of the four to six most
promising "fertile soils". Briefly, testing followed the pattern
outlined below:
A. Collection and chemical analysis of FGD sludges and
municipal wastes to be used in the program.
B. Preparation of sludge mixtures for bench scale testing,
including variations in sludge to sludge ratios and varia-
tions in stabilizing additive addition rates.
C. Physical testing including air-water relationships, poros-
ity, bulk density, and bearing capacity.
D. Germination tests utilizing seed of a selected hybrid corn.
E. Soil permeability and leachate chemical analysis on
mixtures selected for further testing.
F. Bench seedings under controlled conditions with oats,
ryegrass, and soybeans.
G. Chemical analysis of leaf and stem.
H. Chemical analysis of "fertile soils".
Description of Test Procedure
Two flue-gas desulfurization sludges representing different
scrubbing techniques were selected. One represented a high
calcium system and the other was from a scrubber utilizing lime
with approximately 5 to 6 percent magnesium oxide. The high
calcium sludge included 60 percent fly ash and had a total solids
content of 35 percent. The calcium-magnesium sludge was lower
on both counts, having a 48 percent fly ash content and 30 per-
cent total solids. Sewage sludges were selected from a suburban
treatment plant and from a municipal plant which also handled
industrial wastes. In order to stabilize the sludge a commercial
stabilizing agent, Calcilox * additive, was added to the sludge
mixtures.
Several methods of mix preparation were attempted in order
to test variables which could have a potential impact upon
stabilization, and consequently upon the generation of accepta-
ble "soils". The mix preparations for stabilization generally
followed the pattern outlined below:
1. The method of mixing FGD sludge, municipal sludge, and
Calcilox was varied to determine what effect, if any,
variations in the method of mixing would have on
stabilization. Mixing methods were also varied to reflect
the effect of municipal sludge levels of 10 percent and 20
percent by volume of the total mixture on stabilization.
2. The upper and lower limits of municipal waste addition to
the FGD-Calcilox mixture were also determined. This was
accomplished by varying, from 0 to 90 percent, the percent
by weight of solids addition of the municipal waste to the
FGD sludges.
Once the mixtures had begun to stabilize, they were checked
routinely with a pocket penetrometer to determine their relative
firmness. Dravo's operational experience with a wide variety of
sludges has shown that stabilization has taken place when a
bearing value of 4.5 tons/ sq. ft. has been achieved. Thus, this
same 4.5 tons/sq. ft. value was used in the course of this
investigation to determine when stabilization had been accomp-
lished.
As the test mixtures were prepared, three samples of each
mixtures were retained. One for stabilization, one for record
purposes and later reference, and one for permeability testing.
Permeability tests were performed once the samples had been
satisfactorily stabilized and selected for further testing.
The next step in the program was the determination of which
mixtures had internal air-water relationships consistent with
those required of soil. These were measured in terms of the bulk
density (g/ cc), the percent air by volume under 50 cm. tension,
and soil permeability. The values shown in Table III represent
•Calcilox® additive—Patented; registered trademark of DravoCorpo-
ration.
-------
162 Flue-Gas Desulfurization
rcHEMicAL ANALYSES OF SLUDGis]
fpREPAPATlON OF SLUDGE MIXTURES j
[stabilization I
I
*
determinations
OF
AIR-WATEP. RELATIONSHIPS {
| preliminary
I GERMINATION tests
50 cm. TENSION |
-+ POROE-I TV
| BULK DENSITY )
1
SOIL PERMEABILITY AND LEACHATE CHEMICAL ANALYSEsJ
|
rsl
VS J
TESTS WITH OATS
AND SOYBEANS
[lew mid stkm~chemical analyses]
[soil CJIEMICM.
FIGURE 1: Selection Process for "Fertile Soil"
the parameters used in the screening ol soil mixtures with
unknown particle densities.
In order to perform these bulk density, air-water relationships
and permeability tests, the stabilized "soils" were disturbed and
packed in modified Uhland soil test samplers, These samplers
have a uniform volume of 347 cubic centimeters. Once packed
with stabilized material to simulate field compaction the
samples were saturated with de-ioni/ed water and placed on a
specially built tension table. Figure 2. Coincident with this a
germination test was run by placing three kernels of a selected
hybrid corn at a depth of 2 inches ir each sample. The samples
were then left on the tension tabic under 50 em. water tension for
ten days or until germination and sprouting were successfully
completed.
Both the air-water relationships and the germination tests
served as a mechanism for selection of the more favorable
mixtures. These initial germination tests provided a measure of
(1) the consolidation ol the soil and its ability to permit the
penetration of roots through the material, (2) the moisture
holding capacity of the soil, and (3) the relative toxicity of the
soil,
Simultaneously with the air-water relationships and germina-
tion tests, the samples prepared in permeability cylinders were
tested for their respective water infiltration rates. Leachates
from the permeability tests were collected and chemically ana-
fyzed. A thorough evaluation of the soil permeability and
TABI.E 111: Limiting Parameters for "Soil" Materials of
Unknown Particle Densities
Parameter
Min irnurn
optimum
Maximam
Bulk Density (y/cc)
0.B
1-3
1.8
JVir-Vfater cm. tension]
c>
20
40
% air t»y volurxj
Perme-abi itv (in/hr . )
0.1
l .a
2.a
FIGURE 2: Tension Table - Fertile Soils Project
-------
Flue-Gas Desulfurization 163
,4HM
FIGURE 3a: Soybeans, oats and ryegrass growing in selected
fertile soils and Hublersburg (reference soil) (10 days old).
FIGURE 3b: Same as above (17 days old).
leachate chemical analysis combined with the air-water relation-
ships and germination test data then followed, and resulted in
the selection of the best mixtures for further testing.
Once "soils" were selected for additional bench scale testing
they were subjected for further growth tests. In these "pot" tests
the "soils" were placed in five inch plastic pots. The surface was
divided into three sections for seeding, and after seeding the pots
were monitored for a period of five weeks. One of the three
sections was planted with oats, one with soybeans, and the third
with ryegrass. The surface of the pots was covered with one-
eighth inch of sand in order to maintain equal reflective
properties on the surface of all the pots and to negate differences
in heat absorption due to light and dark sludge surfaces.
Throughout the five week monitoring period the samples
were maintained under controlled humidity, and their soil
moisture condition was recorded. In addition, the percent
germination, rate of growth, and over-all appearance of the
plants were routinely recorded and compared to "control plants
growing in selected natural soil of known quality".
Following the pot tests, the leaves and stems of the plants were
carefully cut, dried, and stored for chemical analysis. Those
plant materials and artificial soils which showed the most
promise in the growth tests were then sent to the Merkle
Laboratories of Penn State University for chemical analysis.
Chemical analysis of the soils was completed under the direction
of Dr. Dale Baker, utilizing soil chemistry techniques devel-
oped by him.2 The information developed through these "pot"
tests and associated evaluations was then incorporated in rec-
ommendations for outdoor field trials and additional testing.
CONCLUSIONS AND RECOMMENDATIONS
Based upon the test results generated in Phase I of this project,
it has been successfully shown that FGD sludges and municipal
sludge when properly mixed can be stabilized and will support
vegetation. Several mixtures developed during the course of this
study developed physical properties which were within the range
deemed acceptable for a "fertile soil".
As was previously noted, well over two hundred separate
mixtures were prepared and tested in the early steps of this
project. Of these, sixty-five (65) were found during stabilization
to develop properties suitable for soil testing experiments and
were placed on the tension table for air-water relationships and
germination determinations. Other mixtures were unsuitable
because the extremely low solids content of the waste activated
municipal sludges did not permit stabilization of the mixtures.
The waste activated sludges we had received contained only
0.7 to 2.5 percent solids by weight. Any appreciable percent of
municipal sludge addition would dilute the total mixture to an
extent that stabilization became impractical.
Therefore, municipal waste filter cake, 18.6 to 21.6 percent
solids by weight, was then employed in preparing the mixtures.
This proved to be more satisfactory, although the additional
volumes of water thus introduced to the FGD-Municipal waste
mixtures in the filter cake did lengthen the time of stabilization.
Table IV shows a comparison of the physical properties of the
four most satisfactory soils produced during Phase 1. The
mixtures containing 5 to 20% municipal sludge filter cake were
stabilized with a ten (10) percent Calcilox addition.
Hublersburg is the reference soil which was used throughout
this study. Pond No. 3 is a two year old stabilized FGD sludge
without municipal sludge which has been exposed to the natural
environment.
Bulk density measurements were determined after compac-
tion under moist conditions in the Uhland samplers to a state
similar to that which would be expected under field conditions.
The sixty-five samples thus tested averaged 1.1 g/cc and
displayed a very narrow range, all within the acceptable
parameters. The four selected synthetic soil samplers all had a
bulk density of 1.2 g/cc which is quite close to the generally
accepted optimum 1.3 g/cc.
The priority for the artificial soils was determined and
compared to values normally expected for natural soils, in
general, the porosity values for the stabilized mixtures were less
than those of most soils, but were adequate. The porosity of
Pond No. 3 stabilized sludge indicates that weathering improves
the porosity of stabilized FGD sludges.
Air by volume was determined on the tension table and was
one area where the FGD-Municipal sludge mixtures demon-
strated a deficiency. The minimum air by volume desired was
five (5) percent. All mixtures, including the natural soil,
recorded marginal values for this parameter. This may be
attributed to the fact that the soils were compacted rather than
being in a natural condition. Nevertheless, all of the selected
mixtures showed germination of the seed of a hybrid corn in
three (3) days. Thus, it was concluded that a low air by volume
might not inhibit germination and early plant growth.
Permeability tests and leachate chemistry were also run on the
samples selected for further growth tests. Permeability values
were all quite low, approaching the minimum acceptable value
of 0.1 in/hr., but were acceptable for an artificial soil. Prelimi-
nary chemical analyses of the permeability leachates indicate
-------
164 Flue-Gas Desulfurization
TABLE IV: Comparison of Physical Properties of Synthetic Fertile Soils and a Reference Soil (1)
Sample
Curing Time
Davs
Bulk Density
(q/cc)
Air-Water (50 cm Tensions)
(%) Air by Volume
Total Porosity
by Difference (%)
sprouting Time
(Days)
Hublersburg
Reference Soil
N/A
1.5
6.7
25.8
3
M-ll
5% Munic. B
39
1.2
3.0
14.7
3
M-24
20* Munic. A
50
1.2
2.9
16.4
3
P-12
lOt Munic. B
35
1.2
5.9
17.1
3
p-24
20% Munic. A
49
1.2
6.1
17.0
3
Pond No. 3
No Municipal
Reference Sludge
18
1.1
3.1
27.1
3
that copper, iron, zinc, and manganese are below secondary
maximum contaminant levels for public water systems.3
However, the pH values and sulfate (SO4) ion concentrations
were relatively high, due to the fact that FGD sludges are
generated in an alkaline FGD system.
The pot growth tests with the three plant varieties showed that
the selected synthetic soils supported plant growth almost as
well as natural soil (Figures 3a and 3b). The ryegrass was the first
variety to germinate, followed by soybeans and finally oats.
Soil test results indicate deficient levels of phosphorous and a
pH of 10 to 10.5. These high pH values should be too high to
support plant growth and would normally be expected to cause
a deficiency of several trace elements. However, soil test indicate
that the availability of Fe, Zn, M n, and Cu are within the normal
range.
Some leaf discoloration, particularly at the tips of the plants,
can be observed. This may be the result of an excess of sulfur,
although it may also be a reflection of the phosphorous
deficiency. There is also some indication of lesser deficiencies of
nitrogen and potassium.
Chemical analyses of plant materials also confirms that the
selected stabilized sludge mixtures can support plant life. Leaf
and stem chemistry on the plant residues, for instance, indicates
that the soybeans have normal levels of P, K, Ca, Mg, Fe, Cu,
Al, Zn, and Na. However, they do have a high boron and low
manganese content.
As Phase I is drawn to completion and we begin Phase II, the
field test plots, a number of conclusions have already been made
but several questions remain to be answered. It is expected that
the answers to these questions will be obtained by the experi-
mental data generated in Phase II. In this final phase, a series of
seven field plots will be prepared on which ryegrass, soybeans,
crownvetch, field corn and oats will be grown. The field plots
will be equipped with a rain gauge, gypsum moisture blocks, and
collection equipment for both leachates and runoff. The results
of the Phase U field tests should enable us to make recom-
mendations for a full-scale land reclamation demonstration
project.
In summary, the results generated thus far in this project have
demonstrated that it is possible to combine and stabilize FGD
sludges and municipal waste to produce "fertile soils". While
this material may not have all the properties of a true soil, it
appears that it will be suitable as an amendment in land
reclamation. The results have shown that waste products can be
combined for environmental enhancement.
REFERENCES
1. Pasztor, L., Selmeczi, J. G., and Labovitz, C., 1975; "Stack
Gas Desulfurization Residue Management", Proceedings
National Conference on Management and Disposal of
Residues from Treatment of Industrial Wastewaters,
Washington, D. C„ 12 pp.
2. Baker, D. E„ 1973; "A New Approach to Soil Testing: 11.
Ionic Equilibria Involving H, K, Ca, Mg, Mn, Fe, Cu, Zn,
Na, P, and S", Reprinted From Soil Science Society of
America Proceedings, Volume 37, No. 4, July-August, pp.
537-541.
3. National Secondary Drinking Water Regulations, 1977;
Environmental Protection Agency, Federal Register, Vol.
42, No. 62, March 31, pp. 17146-17147.
-------
Ammonia Removal from
Sanitary Landfill Leachate
by Chemical/Physical
Biological Treatment
INTRODUCTION
The potential for water pollution from sanitary landfill sites
has become recognized in recent years. A number of studies1-3
have documented the great pollutional strength of landfill
leachates. The quality of this material varies with landfill age,
nature and moisture content of the wastes disposed at the site,
and hydrologic and soil factors. In spite of this variability, it can
be stated that, especially for young landfills, the values of the
critical sanitary parameters of leachate are at least an order of
magnitude greater than for domestic sewage. The deleterious
consequences following contamination of ground and/ or sur-
face waters by leachate may be severe, and it is for this reason
that leachate treatment is receiving attention.
Ground and surface waters can be protected if the landfill is
underlain with an impervious membrane. With proper design,
leachate is then directed toward collection points. A waste such
as this, which is properly considered an industrial waste, must be
treated prior to surface discharge. The leachate treatment state-
of-the-art is still embryonic, although a few small scale studies
have been conducted. These have demonstrated that neither
conventional chemical treatment nor biological treatment alone
can achieve the high degrees of treatment efficiency expected
today. Consequently, although we know that the pollution
potential of sanitary landfill leachate can be avoided by inter-
ception using impervious liners, we are not yet able to define the
optimum sequence of unit operations and processes required for
adequate wastewater renovation.
The state-of-the-art concerning the composition and treat-
ment of sanitary landfill leachates has been assessed2.3. The most
obvious characteristics of leachate are its strength and its
variability. Leachate is generally of much greater strength than
domestic sewage. This is especially true in terms of organic
materials and the potentially toxic heavy metals. As important a
characteristic as is the variability of leachate composition.
Leachate quality not only fluctuates from landfill site to site, but
also from time to time at one landfill. Changes over time result
from differences in seasonal hydrology and microbiological
activity. Rainy weather may dilute the leachate, but, at the same
time, may flush out large quantities of pollutional materials. The
typical pattern observed over many years is that the pollution
potential of leachate is greatest during the first five years or so,
but that leachate strength remains significant for as long as ten
to twenty years. This sequence is encountered because the
microbiological processes responsible for decomposing the solid
wastes are relatively slow acting and are first directed at the most
readily biodegradable components of the waste.
It is concluded that considerable differences are encountered
in leachate quality when comparing landfills. In addition to the
R. L. Steiner and A. A. Fungaroli
Applied Technology Associates
Philadelphia, Pennsylvania
and
John D. Keenan
University of Pennsylvania
Philadelphia, Pennsylvania
seasonal, hydrologic and age of landfill factors mentioned
above, there are several other reasons for this observation. The
chemical nature of the wastes accepted at the landfill has a
marked effect on the composition of the leachate. The land
disposal of industrial liquid and solid wastes is critical in this
light.
The variability and strength of leachate have important waste
treatment implications. First, the sheer magnitude of the
measure of pollution potential dictate the use of thorough waste
treatment. Second, the changes encountered from landfill to
landfill are such that waste treatment techniques applicable at
one site are not necessarily directly transferable to other
locations. That is, it may be mandatory that each instance be
separately engineered to achieve adequate treatment. Third, the
flucturations in leachate quality which occur over both short
and long time intervals must be accounted for in the treatment
design. Not only must processes be designed to efficiently treat
the waste flow from minute to minute, but the design must also
reconcile the possibility that treatment techniques which work
well for a young leachate may become wholly inadequate as
landfill age increases.
It is apparent today that sanitary landfill leachate cannot be
treated adequately by just conventional chemical/ physical
treatment or conventional biological treatment. Rather, what is
needed is a combination of the two approaches with perhaps a
supplementary form of advanced wastewater treatment. The
U.S. Environmental Protection Agency, Office of Solid Waste
Management Programs, has awarded a financial assistance
demonstration grant (S—803926) to this project, the prupose of
which is to investigate the effectiveness of alternative treatment
sequences as employed at a full-scale facility in Falls Township,
Pennsylvania. A 380 liter per minute (0.144 mgd) plant has been
constructed to treat leachate from the GROWS (Geological
Reclamation Operations and Waste Systems, Inc.) landfill. This
project, undertaken by Applied Technology Associates, has as
its primary goal the evaluation of the technical feasibility,
operational efficiency and cost-effectiveness of four alternative
treatment sequences. The purpose of this paper is to describe the
ammonia removal train and to present the performance results
obtained during the first eighteen months of operation.
Nitrogen. Nitrogen is a very important constituent of the
biosphere—it forms a part of the backbone of several important
groups of biochemical compounds including proteins and
nucleic acids. In addition to these biochemicals, nitrogen can
occur in a variety of other forms, as reflected by the large
number of oxidation states in which the element can be found.
For example, several key forms of nitrogen include ammonia
(NHj), nitrite (NO, ), nitrate (N03~) and diatomic atmospheric
-------
166 Ammonia Removal
mlrogcn (N,). Over the long term, localized disruptions of this
equilibrium, or biogeochemical cycle, result in temporary peak
levels of one or more nitrogen species with attendant adverse
effects on the ecosystem.
Inimical environmental effects of nitrogen are associated with
high aqueous concentrations of ammonia-N, nitrate-H and
Nitrite-N. These impacts may be summarised as including
promotion of aquatic fertility through the role of ammonium
and nitrate, as well as other nitrogeneous compounds, as plant
nutrients; toxicity of ammonia, especially as a function of pH, to
aquatic organisms; interference with disinfection efficiency due
to formation of chloramines from hypochlorous acid and
ammonium ion; depletion of dissolved oxygen concomitant
with nitrification of ammonia to nitrate; and public health
effects associated with nitrates. For reasons such as these, the
Pennsylvania Department of Environmental Resources estab-
lished the ammonia-N criterion listed in Table 1.
Ix'achate Treatment System. The leachate treatment facility
used in this study is located at the GROWS Landfill in
Tullytown, Fall Township, Bucks County, Pennsylvania. The
plant is designed to provide maximum operational flexibility in
order to permit full-scale testing of a variety of treatment
sequences.
The industry which generates the waste is a sanitary landfill
having a surface area of 50 acres. The landfill will be filled with
about 1,400,000 cu m of refuse over the next several years. The
time required to fill the landfill depends upon many unknown
factors, but it is estimated that it will probably be between five
and ten years. The receipt of refuse is about 800 tons per day.
Eighty-five percent of the refuse is from municipal sources. The
remainder is industrial and commercial. The landfill is also
permitted to accept sewage sludge and selected industrial liquid
wastes.
The landfill is located in the semi-humid northeastern part of
the U nited States. In this region there is a net positive infiltration
of rainfall into the landfill. As long as there is a net positive
infiltration, leachate will eventually begin to be produced in the
landfill. Because of these meteorological conditions and the site
hydrologic situation, an extreme groundwater pollution poten-
tial existed. To alleviate this pollution potential, the Pennsyl-
vania Department of Environmental Resources required the
Table I: Summary of Effluent Criteria for Sanitary Landfill
Leachate Treatment Facility
I"
Parameter
BOO
Amnion ia-N it rogen
Phosphate
Oi1 and Grease
I ron
Zinc
Copper
Cadmi um
Lead
Mercury
Chromium
Maximum Concentration
wq/liter
100.0
35.0
20.0
10.0
7.0
0.6
0.2
0.02
0. I
0.01
0.1
mcmhrinn e u er'a'n by an impervious membrane. This
leach-ite in M?.Cim ?as des'£ned to collect and transport the
operates im i f c ate treatment plant. The treatment plant
vani i »Cr '>crrtllt"s from the Commonwealth of Pennsyl-
Section Envir°nmental Resources Water Quality
effluent criiprw ,elaware River Basin Commission. The
The treai^/'m^ 'acility are summarized in Table I.
the nrox imi» ^ ,enl ls discharged to the Delaware estuary in
terminal I h ^ ° C Warner Company sand and gravel barge
¦'ersev) the rlr'S tldaland at thc nearest gage (Trenton, New
low How is 33d(mvtarCa 'S 6700 st)uare miles and thc ProJected
directly to th. n .i. S PCr s' rtle discharge of treated effluent
'December th*" C,fV!'are ^'veroccurs only during the months of
waste™ r S ACnL Uuri"S remainder of the year, the
capacity in th Infill. The landfill has ample storage
difficulties. The efDupnt '^ S° ^ rccyclmg does not create
nozzles. Is sPread on the landfill using aeration
Figure 1 Ti!'C 'eac'la,e treatment system'is shown in
approximately HHor'Th^16 tr6ated W'th Hme t0 a pH °f
sedimentation the ilkr remoVal of heavy metals- Following
aerate.) |aD« ' V dlKatine supernatant flows by gravity to an
removal The'l. e,S'8ne^ tH Provide equalization and ammonia
with nutrients 1S 'hen neutralizcd and supplemented
parallel 'iprivut a i j n an as"needed basis, and pumped to the
the oxidation % k ge Un'ts- These are designed to provide for
The clarified <-m ° biodegradable organics and ammonia.
<« the Dclawar b°nt 1S then elther chlorinated and discharged
The ammo ' ' °r recycled to the landfill,
upon a comh -rem0Val system included in Figure 1 is based
alkaline pH hint*1'0" i°f- lechniclues: ammonia stripping at
supplemented witffh'tnfication during aerobic treatment,
basis. The ir. r ¦ ea Polnt chlorination on an as-needed
landfill ieachaf lcaVon of these processes to the treatment of
Aqueous nha«p lscussed m ltle following paragraphs,
ammonium ion!" ammonia exists in an equilibrium with the
n is governed by the following reaction;
NH3+h30+%Nh4+ + h20 (!)
solution thisStnp the ammonia ^rom an aqueous
accomplished L1"™ mUst be forced to the left- This is
hydronium ion e eva,lng the pH in order to reduce the
Figure I th^» °,"Centratl.°.n- ,n the treatment system shown in
lime to the rear-t 3 'T c°nd't'ons are provided by the addition of
taTes place fif^h°r|C 'er system- The air stripping of ammonia
'ncreased hv M a^oon ,Figure 1 )and the air-water interface is
ume of thelacm™''0^? rov'ded by a diffused air system. The vol-
ammonia isl, ^ at desi«n flow- Air striPPin« of
and high internal" i5^" elevated PH °f "P to '0, aeration
polyethylene recycle- The lagoon is lined with chlorinated
M.'i
J ,v'«v,
ine bacteria 0" '^n aero')'c microbial process in which nitrify-
bacter, oxidize amm represented as Nitrosomonas and Nitro-
oxidations n™ °nia t0 nitrite and nitrite to nitrate. These
excellent recent' bacter'a with a source of energy. An
synthesis tJSrr °f the Process is available4. The overall
reaction is- mass) and oxidation (of ammonia and nitrite)
NH4++ 1.83 02 + 1.98 HCOj -*•
0021CsH7NO2 +1.041 H20 + 0.98 NOj
+ 1.88 H2C03 (2)
-------
Ammonia Removal 167
Slu
-------
168 Ammonia Removal
Table III: Summary of Results. Column (1) represents operation of system without lagoon, whereas (2) and (3) are for the time period
following lagoon startup. Column (3) data were collected after development of activated sludge, (x - arithmetic mean, n- number of
data points; cv = coefficient of variation).
Samp Itng
Location Parameter
(1)
(2)
(1?
x n cv
x n cv
x n cv
Raw Leachate Alkalinity
Ammon ia-N
BOO
COD
5705 23 0.23
1989 23 1.14
5462 26 0.60
11419 76 0.40
5975 32 0.26
736 27 0.27
8138 26 0.82
11277 105 0.68
2912 26 0.29
*99 21 0.31
8477 20 0.87
11777 76 0.71
Lime Clarifler Alkalinity
Ammonia-N
BOD
COD
3182 25 0.26
1245 26 1.15
2692 25 0.52
5732 74 0.42
3054 21 0.31
533 20 0.19
3725 21 0.42
5481 75 0.39
3082 15 0.36
533 13 0.23
3627 15 0.46
5601 o.4<;
Lagoon Alkalinity
Ammon ia-N
BOD
COD
1659 26 0.30
303 27 0.16
2470 24 0.2.7
4136 100 0.21
'705 20 0.32
306 20 0.17
2333 18 0.27
^°99 72 0.24
¦¦
Effluent Alkalinity
Ammonia-N
BOD
COD
3984 14 0.22
1076 28 0.88
2051 21 1.01
5027 73 0.39
611 31 O.87
82 38 1.68
331 41 2.29
j 936 107 1.20
25 .70
30 32 2.08
66 34 1.12
483 79 0.42
Results
The analytical results for nitrogen flow through the treatment
system are summarized in Table 111. The specific data set upon
which Table III is based was collected during the period
November 1, 1975 through December 1, 1976. The data are
subdivided into three time periods: up to June 14,1976 when the
lagoon was not in operation; from June 14 during which the
lagoon was in use, and from August 1 when a healthy activated
sludge culture was developed.
A more detailed presentation of data is provided in Tables IV
through V1. These are compilations of key operating parameters
and calculated results for the three ammonia removal units.
Table IV is a summary of the lagoon operation. The concentra-
tion of NH, has been calculated from equation (1) using the
observed temperature to determine the equilibrium constant,
the observed pH and the analytical results of the sum of N H4+-N
plus NH ,-N (N, )• Two removals have been calculated. The first,
R i, is based on the influent and effluent concentrations. The sec-
ond, R2, is based upon the total mass in and out. The influent
value was averaged over ten days because of the long detention
period in the lagoon.
A number of operating variables were examined for effect on
the efficiency of ammonia stripping in the lagoon. The most crit-
ical variables in this study were temperature and pH. This
influence is summarized in Figures 2 and 3 in which it is seen that
ammonia removal is apparently independent of pH and temper-
ature. However, as will be discussed subsequently, the two
factors are actually exerting a synergistic effect.
Summary information for ammonia removal in the bio-unit is
presented in Table V. In this table, the notation is as before;
NH4+-N is calculated from equation (1), the pH, temperature
and NT; R , is the fraction of NT which is oxidized in the bio-unit;
and R4 is the specific oxidation rate. The units of R4 are g
nitrogen oxidized per g biomass-day, and it is calculated as the
Table IV; Summary of Lagoon Operating Results. (NT denotes
the total of NH4+ plus NH, as determined analytically. NH3 is
calculated as a function of pH, Nr and temperature. The
calculation of R, and R2 is explained in text.)
Lagoon Data
Removal %
6/10/76
,6/14
6/22
6/30
7/15
7/21
7/27
8/3
8/10
8/20
8/23
8/25
8/27
9/3
9/10
9/13
9/15
9/23
19/29
10/7
10/13
10/19
10/28
11/3
11/13
11/18
11/23
12/2
12/6
12/13
12/11,
12/11
1/4/77
1/10
1/12
1/14
1/21.
1/25
12/1
(NT)
Influent
1(98
456
568
J»73
519
59<«
622
560
202
672
560
571
500
523
437
521
514
537
663
663
557
528
521
350
£H
Temp,°c
A
NH}
...
25.0
241
8.5
25.2
2 77
54
8.I1
26.0
283
J.8
8.5
25.0
325
62
8.6
26.3
308
77
8.9
26.5
350
141
8.3
27.1
290
44
9.2
24.5
323
172
8.7
26.5
255
76
8.7
2«t.5
305
81
8.9
28.8
364
163
8.7
24.it
364
95
8.8
26.5
356
191
8.7
21.3
369
80
B.2
20.8
302
24
8.6
23.7
361*
77
8.6
22.0
364
69
8.7
24.5
322
86
8.9
22.7
367
121
9.1
23.2
255
114
8.9
18.9
218
58
8.7
15.5
240
36
8.0
12.5
227
6
8.5
14.7
235
21
8.9
11.2
275
45
9.4
12.2
296
119
9.6
10.2
319
152
9.2
6.9
319
69
9.0
4.2
1(00
50
10.0
8.0
342
224
9.9
3.2
353
179
9.9
4.1
361
189
9.2
5.0
442
84
10.3
4.0
308
226
10.A
3.0
251
191
10.1
0
233
130
10.1)
0
232
166
10.3
0
231
154
10.1
1.0
230
128
J
-------
Ammonia Removal 169
Table V: Ammonia Removal inBio-Units. N refers to the analytically determined value of NH +-NplusNH , whereas NH +-Nisthe
calculated ammonium ion concentration. R is the removal of N based on influent and effluent concentrations, R is the fraction of N
oxidized, and R is the specific oxidation rate, g N oxidized/g bio-mass-day.
Date
Influent Data
B
o-Reactor
Oata
I
Removals
nt
BOD
coc
Temp.
nt
NH4+-N
pH
800
COD
I
! Ri
r3
*4
5/27/76
549
20 20
4863
24.6
736
---
8.04
2980
9725
0
6/10
241
—
25.0
—
—
—
—
6/14
277
2970
4961
25.2
496
—
7.59
2325
4186
0
6/22
283
3550
4047
26.0
392
—
7.37
2200
1556
0
6/30
325
3670
4351
25.0
330
—
7.80
3710
4656
0
7/15
308
2499
3984
26.3
367
—
7.36
1152
717
0
7/21
350
2049
3915
26.5
302
—
7.57
180
775
.14
7/27
290
2555
3960
27. 1
261
...
7-34
1181
3280
. 10
8/3
322
1763
3672
24.5
297
—
7.74
111
664
.08
8/10
255
1949
3621
26.5
161
—
7.42
30
621
.37
8/20
305
27&0
4843
24.5
36
35
7.45
48
768
.88
.61
.026
8/2 3
364
—
5078
28.8
15
—
7.43
12
406
.96
8/24
364
—
5175
27.5
10
—
7.31
36
420
.96
8/25
364
3780
5080
24.4 { 14
14
7.35
27
384
.96
.63
.012
8/26
360
—
5039
26.5
17
—
7.42
24
526
.95
8/2/
356
—
3347
26.5
6
...
7.22
14
474
.98
8/28
—
—
5118
28.2
1.2
—
7.82
35
299
8/29
...
—
—
27.3
1.5
—
25
396 —
565 \ —
8/30
—
—
5381
24.5
1.5
—
7-59
35
9/3
369
—
4220
21.3
1.9
1.9
7.3
43
546
• 99
.53
.015
9/10
302
—
5061
20.8
2.7
2.6
7.7
310
1053 .99
9/13
364
—
6370
23.7
8.8
—
7.5
—
710
.98
9/15
364
2905
5118
22.0
3.6
3.5
7.6
37
599
• 99
.50
.022
9/23
322
2637
4264
24.5
6.0
5.8
7.7
123
620
.98
.92
.036
9/29/76
367
2660
4360
22.7
1.5
1.5
7.6
83
581
.99
.52
.013
10/7
2 55
1788
3068
23.2
13.2
12.9
7.5
31
299
• 95
10/13
218
1590
2791 !
18.9
5.2
5.2
7.0
52
271
.98
.57
.019
10/19
2 40
1850
3310
15.5
5.8
5.7
7.4
46
295
• 98
.43
.014
10/28
227
—
3170 1
12.5
1.0
1.0
7.6
--
268
¦ 99
.27
.007
1 1/3
235
1750
3454
1<*.7
3.4
l.k
7.6
53
321
• 99
.65
.022
11/13
275
1830
3262
11.2
3.2
3.2
7.
-------
170 Ammonia Removal
500
TO
300
| 200
£
z
100 ¦¦
o bv
„ 7'° 7'5 8,0
rigure 2. Raw Leachate Chemical Oxygen Demand
1,01
.8-
<
>
o
21
UJ
cc
<
z
o
z:
51
<
.6
.4
.2
'<> x x
10
' : .
x
8.5
lagoon pH
15
9.0
20
9.5
x
x
10,0
x
X X
10.5
25
30
the Circled Values Represent Wastewater Temperatures of Less tha"
-------
Ammonia Removal 171
F'gure 5: Effect of pH on Clarifier Effluent Mercury Concentration. The Circled Values Represent Wastewater Temperatures of Less
'han 16°C.
-------
172 Ammonia Removal
NH/|+"N, MG/L
Figure 6: Effect of Low Ammonium Ion Concentration on the Specific Oxidation Rate
Table VI: Operating Data—Breakpoint Chlorination. NT is the total of NH4+-N and NH j-N as determined analytically.
Date
Influent
Effluent
Removal
nt
BOD
COD
PH
Temp
nt
BOD
COD
pH
Dose, mg/1
as C| 2
2/23/77
164
8.2
8.9
153
84
565
8.2
0
.07
2/24
447
6.8
26
577
8.1
115
2/25
159
63
685
8.4
31
79
536
7.7
115
0.81
2/28
31
274
8.3
55
3/1
11.2
15
602
7.0
186
3/2
165
664
8.3
11.4
39
7-5
61
• 76
3/3
165
108
745
8.5
12.3
33
79
745
7.8
76
0.80
3/10
160
15.0
140
666
1559
8.4
0
0.13
toxicity inhibited these efforts. These two difficulties were
overcome by the addition of phosphoric acid as a neutralizing
agent for the lime treatment effluent and by the use of air
stripping of ammonia ahead of the bio-units. Treatment was
successful only after the implementation of these measures and,
as a result, this discussion is limited to the time period after
implementation.
The need for a phosphoric acid supplement became apparent
from three lines of evidence: (a) very low phosphate levels in the
chemical/ physical effluent (BOD.N P =6620:760:1 in contrast
to the usual recommendations which are in the range of
90-150:5:1); (b) unrealistically low values obtained in the
biochemical oxygen demand test; and (c) poor biological
treatment performance following the chemical/physical pro-
cess. These points all indicate that the chemical/ physical
treatment effluent is phosphorus deficient, and that, if biological
-------
Ammonia Removal 173
treatment is to follow, it must be supplemented with phospho-
rus. Additional evidence was collected by performing a series of
BOD5 tests in which a variable amount of phosphorus supple-
ment was added to the bottles. It was observed that the BOD
increased with the amount of phosphorus. In addition, bench
scale tests indicated greater activated sludge production when o-
phosphate was added. Thus, it was concluded that
orthophosphate, as phosphoric acid, should be added as a
nutrient supplement.
The phosphorus limitation and the ammonia toxicity were
overcome with the addition of phosphoric acid and startup of
the lagoon. Within six weeks, an activated sludge developed
which was capable of rapid growth at the expense of the partially
treated leachate substrate. Table 111 clearly indicates that,
although it achieved some destruction of organics, the primary
effect of the lagoon was to reduce the concentration of ammonia
entering the bio-unit to approximately 300 mg/1. Once the
concentration reached this level, the development of a microbial
population was able to proceed, and the effluent criteria for
ammonia nitrogen and BOD were quickly met (Column 3, Table
III).
Numerous efforts were made to examine the effect of
operating variables on lagoon performance. Of particular
interest is the possible effect of ammonia concentration. No
obvious relationship between this variable and lagoon efficiency
exists. This included the use of different expressions for
efficiency (Table IV). In addition, the data were sorted into
subgroups of approximately equivalent pH and temperature.
Within a limited number of these subsets, there was some ten-
dency toward greater removals as a function of increasing
ammonia concentration or loading. However, in general, there
was no apparent relationship between ammonia removals and
the ammonia concentration in the lagoon. This is contrary to
intuition which holds that the aqueous phase ammonia concen-
tration is the driving force for the air stripping process. The lack
of effect of NH3 on R, and/ or R2 implies that another factor (s)
is limiting the process. For this particular installation the
air I water interface which is provided by aeration and internal
recycle is probably limiting the overall efficiency of the
ammonia stripping lagoon.
As shown in Figures 2 and 3, there is an interrelationship
between lagoon performance, pH and temperature. During the
warmer months, when the lagoon temperature was at least
12.4°C, pH levels of 8.2 to 9.0 were sufficient to achieve about
forty percent removal of ammonia-nitrogen and an effluent
value averaging about 300 mg/1. However, when the lagoon
temperature was less than 12.4°C, it was necessary to operate
the lagoon in the 8.9-10.4 pH range in order to provide
equivalent removals and effluent values.
Table VII: Overall Treatment Performance
This system consists of lime addition, sedimentation, air stripping
neutralization, nutrient supplementation and activated sludge.
Many parameters (Table VII) other than ammonia were
altered in the lagoon. There was some stabilization as shown by
the reductions in BOD, COD and dissolved solids. This was
mediated by biochemical processes and the increase in sus-
pended solids is related to the growth of microorganisms, as are
the reductions in sulfate and phosphate. The reduction in
alkalinity and pH is most likely due to aeration effects although
nitrification reactions may partially contribute to the observa-
tion. The reduction of hardness, calcium and magnesium are
related and may be explained by the formation of calcium and
magnesium carbonates.
An additional effect of the ammonia stripping lagoon is the
equalizing effect which, as noted by LaGrega and Keenan9, can
be measured in terms of both flow variability and quality
fluctuations. The presence of the lagoon has allowed the
operator to control the flow leaving the lagoon by control of the
pump settings. This has provided flow equalization to the
biological units. The increased uniformity of the nature of the
waste can be seen in Table III which shows the changes in the
coefficient of variation through the chemical/ physical section of
the plant. The coefficient of variation is the ratio of the
arithmetic mean to the standard deviation, and as such is a
measure of the dispersion of the data about the mean. The
coefficient, which increases as variability increases, exhibits a
general decrease through the lagoon.
The removal of ammonia in the bio-unit is due to the
combined effect of the microbial oxidation of NH4+-N to
NO, N and the physical stripping of NH3-N as a result of
seration in the activated sludge process. There was no simple
relationship between organic matter and nitrification measured
as the specific oxidation rate. No nitrification took place when
the BOD exceeded 1000 mg/1 and when the COD exceeded 3000
mg/1. However, once an activated sludge developed, there was
no consistent relationship between the concentration of organic
matter and nitrification. The biomass which developed was
capable of nitrification even when the bio-unit influent concen-
tration of BOD and COD averaged 2400 and 4100 mg/1,
respectively, as long as the influent ammonia concentration
averaged about 300 mg/1. At high ammonia levels, however, the
toxicity of ammonia predominated and very little oxidation of
organics or ammonia took place.
Figure 4 shows a clear dependence of the specific oxidation
rate upon temperature. The curve of Figure 4 agrees well with
curves developed theoretically in the recent Environmental
Protection Agency manual4. The agreement becomes better
when the estimated fraction of nitrifying bacteria in the biomass
is considered. This fraction is calculated in a straightforward
manner from the amounts of BOD and NH3 oxidized and from
the estimated yields of nitrifiers and BOD oxidizers. From Table
III, Column 3, the average BOD oxidation is 2276 mg/1 and
(from R3, Table V) the average nitrogen oxidation is 147 mg/1.
Assuming that the respective cellular yields are 0.15 g biomass/ g
nitrogen oxidized-day, and 0.55 g/ g BOD oxidized-day4, then
the fraction of nitrifiers in the biomass is 0.02. Taking this value
into account, the curve of Figure 4 is somewhat lower than
would be expected based on the theory, and the most probable
reason for this is the inhibiting influence of such components of
the leachate as heavy metals, organics, and so forth.
A number of leachate parameters were examined for potential
inhibitory effects on the specific oxidation rate. As mentioned
above, a consistent influence of organic materials, measured as
BOD and COD, on nitrification could not be uncovered.
However, based upon the literature4, it is reasonable to expect
that some of the inhibition noted above is related to the
relatively high BOD and COD concentrations present in the
biological reactor.
The most significant cause of the inhibition is that due to the
substrate, NH4+-N, itself. This is shown in Figures 5 and 6,
Concentration
Percentaqe Removal
Influent
Effluent
Suspended Solids
587
84
85.7
Dissolved Sol ids
12,004
4,830
59.8
COD
11,777
483
95.9
BOD
8.477
66
99.2
AlkalInlty
5,912
487
91.8
Hardness
5,716
1,284
77.5
Magnesium
566
107
81.1
Ca1c i um
954
336
64.8
Chloride
3,172
2,925
7.8
Sulfate
272
603
—
Phosphate
1.65
15.6
—
Amnion ia-N
699
30
95-7
Kjeldahl-N
767
46
94.0
-------
174 Ammonia Removal
where the data plot as a clear case of substrate inhibition. It
should be noted that all the data were used in the preparation of
this surve, and that, therefore, considerable scatter is
incorporated because of differences in pH, temperature and
other operating variables. Figure 6 provides an expanded scale
version of the same plot which shows a more classic Monod
relationship at the lower NH4+-N concentrations. These values
correspond to the situation encountered in the treatment of
domestic sewage, and therefore Figure 6 resembles the type
curve usually presented. However, for design in industrial
situations where concentrations are high, the substrate inhibi-
tion phenomenon must be considered.
The difficulties in obtaining a healthy culture of activated
sludge were oveicome. The operating experience indicates that
the earlier problems were in fact due to ammonia toxicity and
phosphorus limitation. The ammonia stripping lagoon has
maintained the concentration of this inhibitor below toxic lev-
els. The mean and standard deviation of the lagoon effluent
ammonia concentration are such that 99 percent of the time, the
feed to the activated sludge unit is less than 460 mg NH, N/ liter.
The corresponding raw leachate concentration is 900 mg
NH, N/ liter. Thus, the lagoon has functioned to minimize the
shock loading effect of inhibitory ammonia concentrations.
This in turn provided an opportunity for the development of
microorganisms capable of extracting carbonaceous BOD. As
this group became established, organic concentrations in the
mixed liquor were reduced and this created conditions suitable
for the development of nitrifying organisms. Growth of these
groups of microorganisms has resulted in the low effluent
concentrations of both BOD and ammonia.
Chian and Dewalle have recently completed an extensive
review of leachate treatment techniques2. Their conclusion was
that leachate collected from recently leaching landfills is best
treated biologically. This is because the organic fraction of such
leachate is composed predominantly of free volatile fatty acids
which are readily biodegradable by either aerobic or anaerobic
means. On the other hand, leachate from older landfills is more
efficiently handled by chemical-physical processes, because
these organics are more resistant to biodegradation. They also
concluded that activated carbon and reserse osmosis were the
most efficient chemical-physical methods in terms of the
removal of organics. The results obtained here to not do not
completely substantiate this conclusion of Chian and DeWalle
in that pretreatment in terms of lime treatment, air stripping of
ammonia and nutrient addition were needed in order to devel-
op an active population of biomass.
As seen in Table III, a considerable change in alkalinity
occurs during biological treatment. There are two main mecha-
nisms by which this occurs. First, the aeration causes some
removal of gaseous carbon dioxide, resulting in a shift of the
carbonate equilibria and a change in total carbonate alkalinity.
It is probable, however, that in this case, nitrification has a more
profound effect on alkalinity. As a result of nitrification,
alkalinity is consumed and carbon dioxide is produced.
Neglecting the effect of biomass synthesis, the theoretical value
is 7.14 mg alkalinity as CaCO, destroyed per mg NH„+ N
Table VIII: Operation and Maintenance Costs Incurred During
the Operation of the Overall Treatment System (1 cubic meter-
263.95 gal., 1 kg = 2.2051b.)
la /.It U»6 _ w
oxidized. In this study, a ratio of 4.5 mg alkalinity per mg
NH4+-N removed has been observed since the development of
the activated sludge culture. This is in excellent agreement with
the theoretical value if one considers that the observed value
includes the effects of biomass growth, the effect of air stripping
in the bio-units, as well as shifting chemical equilibria in
addition to those of nitrification.
The results presented in Table VII demonstrate the high level
of attainable overall treatment efficiency. This treatment system
can achieve removals greater than ninety percent for ammonia,
BOD, COD, alkalinity and kjeldahl-N; and greater than two-
thirds for suspended solids, hardness and magnesium. Costs
Operational Period
Total Flow, gal.
3,771.004
Lime used, lb.
lb/1000 gal.
102,850
27.3
Sulfuric acid , gal.
ga1/1000 ga1.
303
.080
Phosphoric acid, gal.
ga1/1000 gal.
69.75
.018
Costs, $/1000 gal
Power
Lime
H2S01,
H3POI,
$1.26
0.82
.07
.ok
Total
$2.19
incurred during the operation of this system are summarized in
Table VIII. The operation and maintenance costs are shown for
the operational period following the initial startup phase
(8/1/76 12/31/76). The data indicate a cost of $2.19 per
thousand gallons treated.
The high power costs reflect the demand for electricity for
leachate pumping, effluent pumping, and maintenance of the
laboratory in addition to tl\e requirements for actual treatment.
The cost of manpower is approximately 20 hours per week.
CONCLUSIONS
1. The raw leachate is characterized by high organic
strength, high ammonia concentrations, and large day-
to-day variations.
2. It has been concluded that this raw leachate must be
pretreated in order to render it amenable to activated
sludge processing. The results indicate that the raw
leachate inhibits the growth of the activated sludge
microorganisms. Although the presence of heavy metals
and low levels of phosphorus contribute to this inhibi-
tion, it is clear that the excessive concentrations of
ammonia-nitrogen are primarily responsible.
3. The complete chemical/ physical treatment sequence
consisting of lime precipitation/ sedimentation/ air strip-
ping achieved the following levels of removal efficiency:
65 72 percent of the organic matter and 56 percent of the
ammonia-N.
4. Temperature and pH exert a synergistic effect on the
efficiency of the ammonia stripping lagoon. Higher pH
levels were needed for equivalent removal efficiencies
when the waste temperature dropped below 12.4°C.
5. Specific oxidation rates of up to 0.036 g nitrogen
oxidized per g biomass-day were achieved in the bio-
units.
6. The relationship between the specific oxidation rate and
the concentration of ammonium ion indicated that
substrate inhibition is operative in the bio-units receiving
leachate.
7. The specific oxidation rate increases exponentially with
wastewater temperature.
-------
Ammonia Removal 175
8. Activated sludge treatment of the effluent from the
chemical/ physical units has been extremely successful. It
is apparent that the reduction in ammonia-N afforded by
the air stripping lagoon made conditions more suitable
for the growth of activated sludge microorganisms. The
lagoon provides ammonia removals of approximately 43
percent resulting in activated sludge influent concentra-
tions of 150-462 mg NH4+-N/ liter (99 percent confi-
dence interval). Under this condition, the activated
sludge quickly adapted to the leachate with the result that
effluent BOD, concentrations have been consistently less
than 100 mg/liter. Nitrifying organisms have developed
and produced a nitrified effluent with very low
concentrations of ammonia.
9. Overall, the treatment sequence consisting of chemical/
physical (lime precipitation, sedimentation, air stripping,
and neutralization) followed by activated sludge has pro-
duced final effluent with the following characteristics:
1. Organic matter has been reduced to 66 mg BOD5/liter.
This corresponds to 99 percent removal. The corres-
ponding COD removal efficiency is 96 percent. The
effluent BOD to COD ratio is 0.14.
2. The effluent ammonia concentration is 30 mg/ liter,
representing 96 percent removal.
10. During cold weather operation, breakpoint chlorination
may be used to augment other ammonia removal
methods in order to achieve discharge standards.
ACKNOWLEDGEMENTS
This research was supported in part by the United States
Environmental Protection Agency, Office of Solid Waste,
through Demonstration Grant No. S 803926. The assistance of
Mr. Bernard Stoll, Project Officer, has been most helpful.
REFERENCES
1. Steiner, R. L. Chemical and Hydraulic Characteristics of
Milled Refuse. Ph.D. Thesis. Drexel University, Philadel-
phia (1973).
2. Chian, E. S. K. and F. B. DeWalle. "Sanitary Landfill
Leachates and Their Treatment". Proceedings ASCE,
Journal of the Environmental Engineering Division 102,
EE2, 411-31 (1976).
3. Steiner, R. L., J. D. Keenan, and A. A. Fungaroli.
Demonstration of a Leachate Treatment Plant. Annual
Report to U.S. Environmental Protection Agency, Office
of Solid Waste Management Program. Demonstration
Grant No. S-803926. 64 pp. (1976).
4. Technology Transfer—EPA. Process Design Manual for
Nitrogen Control. Oct. 1975.
5. American Public Health Association, American Water
Works Association and Water Pollution Control Federa-
tion. Standard Methods for the Examination of Water and
Wastewater. 14th Edition. Published by APHA, New York
(1976).
6. American Society for Testing and Materials. Standards.
Part 23 (1972).
7. U.S. Environmental Protection Agency. Manual of
Methods for Chemical Analysis of Water and Wastes, 2nd
Edition. EPA-625/6-74-003 (1974).
8. Analytical Procedures for Chemical Pollutants, Pollution
of Subsurface Water by Sanitary Landfills. Research grant
EP-000162, NT1S, Springfield, Virginia.
9. LaGrega, M.D. and J. D. Keenan. "Equalization of Sewage
Flows". Journal Water Pollution Control Federation
(1974), 46 1, 123-32(1974).
-------
Disinfection of Treated
Landfill Leachate
Using Sodium Hypochlorite
Chongrak Polprasert
International Development
Research Centre
Ottawa, Canada
and
Dale A. Carlson
University of Washington
Seattle, Washington
INTRODUCTION
According to Brunner and Kellar7, more than 90% of solid
wastes collected in the United States are disposed of in open
dumps or sanitary landfills and only 5% of these disposal sites
meet accepted standards. Of 5,000 land disposal sites surveyed
by the USPHS (1968), 25% had surface drainage problems, 20%
had leaching problems, and 15% were reported to have the
lowest part of the fill in groundwater.
In recent years, there has been greater concern about the en-
vironmental impact of sanitary landfills. Sufficient evidence
from many investigators indicated that impairment of surface
and ground waters can be caused by leachate generated from the
landfills (Anderson and Dornbush 2; Culham and McHugh
and Burchinal and Oasim 8). Based on their own studies and
others, Engelbrecht and Amirhor13 reported the original densi-
ties of coliform bacteria and fecal streptococci present in
leachate to be in the ranges of 10M06 bacteria/ml and these
numbers decreased by more than 90% within 150 days of
leaching from the fills. Sporadic occurrence of enteric virus in
leachates has also been cited by Sobsey, et al.28 and Copper, et
al.10 from which their later pilot study revealed evidences of
virus retention in the lysimeter caused by virus inactivation in
composite leachate samples and virus adsorption to various
inorganic salts of leachates (Sobsey, et al. 29)-
With regard to health aspects, the potential hazards from
pathogenic agents would primarily depend on: the magnitude
and nature of the pathogens initially placed in the fill; the ability
of the pathogens to survive, reproduce and retain their infection
properties in the landfill environment; and the ability of the
pathogens to move through the landfill into adjacent environ-
ment such as into ground or surface waters and thus become a
potential hazard to man. Although removal of organisms
through soil was found to occur largely by adsorption, the
organisms could become deadsorbed with changes in water
quality (Gerba, et al.16). Once entrance has been gained into the
underground aquifer both bacteria and virus have been
observed to travel as far as several hundred feet (Klein, et al.17).
Recent studies by Schaub and Sagik27 indicated that clay-
adsorbed viruses retained their infectivity in tissue culture
monolayers and in mice. Only one virus particle is needed to
initiate infection or constitute a minimum infective dose (MID)
for the system employed (Plotkin and Katz21). It has been
estimated that 100 bacterial cells are needed to produce 1 MID
under optimum conditions (Boventre and Kempe6). Viruses
survive at least as long as pathogenic bacteria in soil, e.g. 2-3
months (Gerba, et al.I6).
As related to the foregoing problems, it becomes apparent
that leachate should be collected and treated before it is
discharged to the environment. The objectives of this research
reported herein were to:
1. Determine the presence and density of bacteria and viruses
in leachate prior to and after activated sludge treatment units.
2. Study chlorination characteristics and the disinfection
efficiency for bacteria and virus removal in the treated leachates.
3. Develop the inactivation kinetic models for survival of the
microorganisms during the chlorination process.
Materials and Methods
The Cedar Hills sanitary landfill, located south of Seattle,
Washington which receives municipal solid wastes and
anaerobically digested sludge was selected for this study.
Leachate samples were collected from the leachate spring
emanating from the lanfill base and were stored in the 4° C room
until used. All experiments were carried out as the Civil
Engineering Department, University of Washington except the
detection of poliovirus in leachate which was conducted at the
Municipality of Metropolitan Seattle (Metro) laboratory. Four
bench scale complete-mix continuous-flox activated sludge
units were employed for treatment of leachate and the results
have been described in details elsewhere.25
The analytical procedures outlined in Standard Methods3 and
EPA's Methods for Chemical Analyses of Water and Wastesu
were followed. Some variations or those not included in the
foregoing methods are described below.
NH?, N02 , and NOj" : Samples were filtered through 0.45
um millipore filters to remove suspended solids. When neces-
sary, deionized-distilled water was added to dilute the filtrates.
Both analyses of NH,-N and N02 , NO, -N (using CU-Cd
reduction column) were conducted separately with a Technicon
Autoanalyzer II.
Total Hardness:Total hardness was determined by the EDTA
titrimetric method in which sodium cyanide in powder form was
employed as inhibitor to the interferences.
Chlorine Residuals: Since chlorine residuals were determined
at short time intervals, the Ortholidine-Arsenite (OTA) method
was adopted for this study. Chlorine concentrations were
measured by the spectrophotometry method and the instru-
ment employed was Perkin-Elmer UV-VIS Spectrophotometer
Coleman 139,
Bacterial Enumeration: The membrane-filtration technique
was chosen for this experiment because large sample volumes
hence more representative water samples, could be applied to
the filter units. Apart from that, the numerical results obtained
have been reported to have greater reproducibility than is
expected from the multiple-tube (MPN) method (MiUipore
Manual". A list of dehydrated media for each type of the
-------
Disinfection 177
bacteria enumerated is as followed: Total coliform-Difco M-
End o medium no. 0749; Fecal coliform-Difco M -FC Broth Base
no. 0883; Fecal streptococci -Difco M-Enterococcus Agar no.
0746; and Lactose non-fermenting bacteria-Difco SS Agar no.
0074. Some colonies from the SS agar plates were further tested
for pathogenic organisms using the API 20E system (Analytab
Products Inc., N.Y.) It is a microtube system designed for the
performance of 23 standard biochemical tests from a single
colony of bacteria. Identification was accomplished with the
Analytical Profile Index4 using a 7-digit profile.
Virus Enumeration: The detection of poliovirus in leachate,
including virus concentration and plaque assay, was carried out
according to the techniques described by Sobsey, et al.29. The
overlay-agar technique by Adams' was adopted for assaying the
bacteriophages.
Disinfection Experiments: T-4 coliphage (wild type) and E.
coli B were employed as models for pathogenic virus and
bacteria, respectively. Diluted chlorine bleach (The Commis-
sion Co., Inc., Seattle) having an original concentration of
5.25% NcOCl was used as the disinfectant, and a 30% Na2S203
solution was used as reducing agent to the chlorinated samples.
For each chlorinated sample seeded with T-4 virus, prior to the
phage assay about 0.3 ml of chloroform was added to the
solution to inactivate all E. coli bacteria, thus preventing them
from acting as host cells to the coliphages after the NaOCl was
already neutralized by Na2S203. The inactivation process, being
conducted at room temperature, was performed as a batch
system in 300 ml beakers whose contents were constantly stirred
at 250 rpm by magnetic stirrers. Other details of the disinfection
experiments have been reported elsewhere23.
Results and Discussion
Microbiological Characteristics of Various Leachate
Samples
An experimental arrangement for microbiological studies is
shown in Figure 1. Leachate was diluted separately with tap
water and primary sewage at a ratio of 2:1 (by volume) to enable
its treatability by the activated sludge process. The purposes of
having two influent sources were to provide control and data
comparison between comparable units. The characteristics of
raw leachate, influents and effluents of the activated sludge units
are present in Appendix A.
Influent I
Leachate
+
Tap water
Leachate
+
Primary Sewage
A.S.
A.S.
unit 1.1
unit 1.2
X 7
Effluent E-l
A.S.
A.S.
unit 2.1
unit 2.2
Effluent E-2
A.S. - Activated Sludge
Figure 1: Experimental Arrangement for Microbiological Stu-
dies
Bacterial Data: Data of the bacteriological analyses are sum-
marized in Table I. No total and fecal coliforms were detected in
raw leachate during the investigation period but sporadic
occurrence of fecal streptococci and lactose non-fermenting
bacteria was observed. This finding is similar to Engelbrecht and
Amirhor11 who indicated greater stability of fecal streptococci
and S. typhi in leachate over fecal coliforms. However, when
diluted with tap water and aerated for a few days (such as
Influent 1) there were great increases in bacterial densities of all
four types examined and their numbers were quite stable
throughout the experiment. Bacterial densities of Influent 2
were slightly higher than Inlfuent l's because there was
contribution of microorganisms from primary sewage. The
bacterial characteristics of Effluents E-1 and E-2 were typical of
normal secondary effluents.
It is postulated that microorganisms residing in leachate are in
the growth-inhibitory stage caused by concentrated constituents
of organic and inorganic compounds present in the leachate
itself. From his autobiographic study, Riley25 found that acetic,
propionic, and butyric acids were inhibitory to coliform organ-
isms. Pritchard22 reported that it required at least 96 hours
of leachate incubation before gas-formation was observed in the
multiple-tube technique. Long incubation periods (2-3 days)
could provide opportunity for bacteria to overcome previous
inhibitons to growth. These findings may be applied to explain
the report of Engelbrecht and Amirhor13 who indicated that
density of bacteria originally present in leachate decreased while
the physical and chemical constituents increased with time of
leaching during the first 90-150 days of lysimeter operation. The
volatile acids, heavy metals, and solids, which came out with
leachate could possibly associate with and/or suppress the
organisms from becoming active. If leachate were diluted,
together with changes in pH and D.O., the organisms could
become active again in the more favorable conditions (i.e.
Influent 1).
About 50 colonies of the lactose non-fermenting bacteria
from the SS agar plates of Influent 1 (leachate + tap water) which
were oxidase-negative were further inoculated into the API 20E
strips and the results are presented in Table II. One each of
Shigella and Salmonella isolate were identified from strips no.
21 and 22, respectively, but no serological test was further per-
formed to confirm the species. Others were found to be normal
coliform organisms. Another extensive and qualitative study by
EPA region X (Vasconcelos32) also revealed one positive
Salmonella enteritidis (biochemically and serologically con-
firmed) isolate out of 3 gauze pads suspended for 1 week in the
leachate stream below the Cedar Hills landfill.
Viral Data: Experiments were conducted 3 times at different
seasons in 1975 to detect the presence of pilioviruses in raw
leachate. Twenty liter samples were concentrated 100 times by
the double-filter adsorption technique and assayed by the
plaque-forming-unit method. Although the concentrated lea-
chates were not found to be toxic to the mono-layer cultures of
Hela cells, there were no plaques formed during the
investigation period. This negative finding is similar to other
reports cited previously. Factors which could be responsible for
sporadic occurrence of viruses include: low virus recovery
efficiency of the technique employed (37% on the average), time
of sampling, and environmental conditions in the landfill the
leachate itself.
Sample concentration was not performed for bacterial virus
analyses and only 0.1 ml of samples were inoculated directly
onto the tryptoneplating agars. No bacteriophages were
detected in raw leachate but a few ranging from 10 to 930
plaque-forming-units (PFU)/ ml were present in influents and
effluents of the activated sludge units. These results were similar
to the bacteriological data discussed in the foregoing section.
According to the available information obtained, it would
appear that there are various species of enteric organisms which
can be "pathogenic opportunists" present in landfill leachate.
These organisms, including bacteria and viruses, could not be
easily detected due to interferences from organic and inorganic
-------
178 Disinfection
constituents in the leachate itself. Once entrance is gained into a
more favorable environment and sufficient time was available to
overcome their inhibitions to growth, the organisms could
proliferate again, thus causing a potential health hazard to man.
Disinfection of Treated Leachates
Effluents from the activated sludge units (refer to Figure 1)
were seeded with coliphage T-4 and E. coli B (provided by
Doerman, 1976) prior to disinfection experiments. A stability
study revealed that within a 60-minute contact time the treated
effluents were riot harmful to the seeded organisms. Since
Effluents E-l and E-2 came from different influent sources, it
was then possible to compare chlorination data between the two
water samples whose characteristics, especially NH, and hard-
ness, were different from each other as are indicated in Figures 2
and 4, respectively.
Results of the disinfection experiments are summarized in
Figures 2-5. Each data point is an average of at least 5 replicates.
Initial organism kills that occurred during the first few minutes
were caused by the presence of free chlorine residuals and the
magnitude of kills were proportional to chlorine doses. The
inactivation rates, represented by slope values, are also found to
increase directly with chlorine doses and it was demonstrated
that combined chlorine residuals had the ability to inactivate T-
4 virus. Another observation was that although bacterial resis-
tance to chlorination was less than for virus they both exhibited
the same die-off characteristics, and excellent kills of virus were
obtained at dosages beyond the breakpoint chlorination.
Comparison of disinfection data between the two effluent
samples revealed greater inactivation rates in Effluent E-2 over
Effluent E-1 (Figure 2 vs Figure 4, and Figure 3 vs Figure 5) even
though their weight ratios of NH j/Cl2 and their survival ratios
(N/N„) at the 2-minute contact time were approximately the
same. Since total hardness content in the E-2 sample was about
90 mg/1 less than in E-l, an experiment was conducted to
investigate the shielding effects of hardness on disinfection as
has been reported by Reid and Carlson24. The results obtained
(Figures 6 and 7) indicated that hardness interfered with
disinfection to some extent. However, its magnitude of protec-
tion was not great enough to compensate for the difference in
inactivation rates between the two effluent samples as was
mentioned previously. From their chlorination studies, Morris
and Wei2" and Saunier and Selleck26 reported that the speed of
chlorination reaction was approximately proportional to the
initial NH, concentration of the water sample. High NH3
concentration in Effluent E-2 which enhanced the chlorination
rate would, in the same way, accelerate the reactions between
chlorine and certain en/ymes of the organisms that were
essential to the cells' function. The E-l sample had a low initial
NH, concentration, hence its slow inactivation rates as com-
pared to Effluent E-2. A further study is recommended to
investigate into more details the effects of NH, on the rate of
organism inactivation during chlorination process.
Analyses of chlorine residuals revealed that most of their
concentrations after a 10-minute contact time were less than 1
mg/1 for bacterial disinfection and varied from 10 to 50 mg/1 for
viral disinfection. No significant correlation between the con-
centrations of chlorine residuals and the magnitude Of organism
kills was observed during the investigation period.
The Kinetic Models of Inactivation
It is apparent from Figures 2 5 that the disinfection data did
not conform to Chick's' law indicated in equation (1) such as the
relationships between the organism survival ratios (N/N„) and
contact times could be plotted as straight lines on log-log paper,
and the inactivation rates increased directly with chlorine doses.
The term C which represented chlorine doses was introduced to
the right side of equation (1) and N and C were adjusted to the
powers of n and m, respectively, as is shown in equation (2).
Chick's law dN/dt = -k.N (1)
Modified Chick's law dN/dt = -k.Nn.Cm (2)
where
N = number of organisms at time t, CFU/ml or PFU/
ml
N = number of organisms when t equals o, CFU/ml or
PFU/ml
C = Dosages of the disinfectant, mg/1
Table I: Bacteriological Data of Various Leachate Samples and Primary Sewage (Experimental Period: Feb. 12 - March 2,1976). All
units expressed as *CFU/100 ml.
Bacteria
Raw
Leachate
Primary
Sewage
Influent 1 1
Leachate+Tap
Water
Effluent r.-l'
(1.1 + 1.2)
Influent 2*
Leachate +
Prim. Sewage
Effluent E-2*
(2.1 + 2.2)
Total coliform,Range
Mean
P50
N.D.
N.D.
13xl03-53xl05
25 x 105
10 X 105
•» 4
76x10-86x10
29 X 104
24 X 104
19x103-11x104
46 x 103
40 x 103
21xl04-74xl05
27 x 105
13 x 105
66xl02-35xl04
10 x 104
4 x 104
L-1L
Fccal coliform,Range
Mean
P50
N.D.
N.D.
16xl02-88xl04
21 x 104
5 x 104
13x102-16x104
57 x 103
26 x 103
80xl01-80xl02
39 x 102
30 x 102
13xl02-ltxl04
50 x 103
13 x 103
30xl01-10xl04
17 x 103
2 x 103
Fecal streptococci.
Range
Mean
P50
80-28xl02
11 X 102
55xl02-16xl04
82 x 103
54 x 103
10xl02-85xl03
29 x 103
10 x 103
12xl01-32xl02
14 X 102
8 X 102
83xlOJ-91xl05
46 x 103
41 x 103 .
21xl01-52-102
14 x 102
8 x 102
Lactose non-fermen-
ting-bacteria,
Range
Mean
P50
760
760
45xl03-21xl04
12 x 104
11 x 104
40xl01-40xl03
17 x 103
11 X 103
Ilxl02-25xl03
62 x 102
29 X 102
13xl03-40xl04
19 x 104
13 x 104
21xl01-39xl02
18 x 102
24 x 102
*CFU - colony-forming - units
*With reference to Fig. 1
N.D.
P50
- not detectable
• 50* Probability of Bacterial Density not exceeding
-------
Disinfection 179
t = contact time, minutes
k, n, and m = disinfection constants
CFU = bacterial number, expressed as colony-forming-
units
PFU = viral number, expressed as plaque-forming-units
(N/N )"^n_1 ^ = (n-l).k.N^11"1^ .Cm .t + 1
(3)
By assuming that the underlined term on the right side of
equation (3) is greater than 10, the term 1 on the same side could
be neglected because the difference between log 10 and log 11 is
less than 5%. (It was later found that this assumption was valid
within the range of 38%-83% of all C.t used in the experiments.)
The disinfection coefficients k, n, and m for each organism and
water sample could then be solved by taking C and conse-
quently t as constants, and utilizing the average slope values
present in Figures 2-5. Data beyond breakpoint chlorination
were not included in the calculation because the organisms were
inactivated to such a large extent that they were uncomparable
to chloramination.
The developed dinetic models of inactivation with chlorine
using the data from these experiments are present below.
For T-4 virus in Effluent E-l:
For T-4 virus in Effluent E-l:
dN/dt = -1.15 X 10"26 ,N2-79 ,C7'85 (4)
For E. coli-B in Effluent E-l:
dN/dt = -2.26 X 10"7 ,N156 .C2-28 (5)
For T-4 virus in Effluent E-2:
dN/dt = -5.08 X 10"13 .N1'72 ,C3-66 (6)
For E. coli-B in Effluent E-2:
dN/dt = -1.39 X 10^ .N1'28 C2 04 (7)
The predicted survival ratios (N/ NQ) of organisms at various
chlorine doses and contact times using equations 4-7 are
selectively presented and compared with the experimental data
in Figures 8 and 9. Although some discrepancies occur, data for
both effluents seems to fit the models quite well. Some factors
that may have significant effects on disinfection but were not
included in the developed models are: organism clumping,
organism association with solids, and the inter-reactions
between chlorine, the organisms, and the surrounding environ-
ment. The penetrating power of chloramines into organism
clumps and/ or their reactions with the organism enzymes are
considered not effective and slow. So, during the first 10-20
minute contact time the magnitude of kills were not as great as
the models predicted, especially in bacteria inactivation (Figure
8) where small chlorine doses were applied. Later on, the
experimental data showed greater kills than the models
prediction which could be indicative of kills brought on by
chlorine diffusing into clumps or individual cells as has been
experienced by Reid and Carlson24. Withahigherdriving force,
i.e. 105 mg/1 NaOCl in Figure 9, diffusion of chlorine into
clumps was accomplished at a much faster rate and conse-
quently, the magnitude of kills was greater than the predicted
values at an earlier period, i.e. 5-10 minutes. The application of
these models to actual operations is considered to be practical
because only disinfectant dosages and contact times were
involved in the calculation.
It is interesting to note from Figure 9 that data on viral
inactivation at chlorine doses beyond the breakpoint had larger
deviations than the others with smaller chlorine doses. Doer-
man12 hypothesized that the "multiplicity of reactiviation" phe-
nomena caused by DNA loci transfer as was experienced by
Lauria1*) when he exposed the coliphage T-even strains to UV
light could possibly be responsible for the data fluctuation.
There have not been reports on whether other enteric viruses
such as the RN A strains would exhibit this type of reactivation.
Since the density of viruses occurring naturally in the environ-
ment is small, their chances of reactivation by means of loci
transfer would be minimal.
The relationships between product of disinfection dosages
and contact times (C.t) and organism survival ratios (N/N„)
could be developed by integrating equations 4-7 into the same
form as equation (3) and neglecting the term 1. As is shown in
Figure 10, it is apparent that the commonly assumed relation-
ship Cm.t = k was found to be too simplistic to support the
already existing data because the same product of Cm.t did not
provide the same organism kills if there were changes in C or t.
Instead, the organism die-off followed the empirical relation-
ship Cm.t =k,(N/ NH)~(n~ 1) (kpconstant), according to the de-
veloped models such as equations 8 and 9 that are present in
Figure 10.
CONCLUSIONS
The results obtained from this study indicated that landfill
leachate could be a potential source of health hazard to man.
Although no virus and few bacteria were detectable in raw
leachate, their numbers increased several folds in the aerated
diluted leachates. The chlorination experiments revealed that
apart from chlorine doses and contact times, NH3 could also be
a factor that enhanced the organism inactivation rates, while the
opposite occurred with total hardness. The developed kinetic
models of organism inactivation showed considerable
agreement with the experimental data and are considered to
practical for uses in actual operation.
ACKNOWLEDGEMENTS
The authors acknowledge and appreciate the assistance
provided by Dr. A. H. Doerman of the Genetics Department.
University of Washington, Bob Swartz of the Municipality ol
Metropolitan Seattle, and Jay Vasconcelos of the USEPA
Region X Laboratory.
REFERENCES
1. Adams, M. (1959), Bacteriophages, Interscience Publ. Inc.
New York.
2. Anderson, J. R., and Dornbush, J. N. (1967), "Influence of
Sanitary Landfill on Ground Water Quality," J A WW A,
Vol. 59, No. 4, pp. 457-470.
3. APHA, AWWA, and WPCF (1971), Standard Methods
for the Examination of Water and Wastewater, 13th Ed.,
APHA Publ., Washington, D.C.
4. API (1976), The Analytical Profile Index, Analytab Pro-
ducts, Inc., New York, N.Y.
5. Beard, J. W. (1965), "Host-Virus Interaction in the Initia-
tion of Infection," G. Berg (ed.), Transmission of Viruses by
the Water Route, Interscience Publishers, New York, pp.
167-192.
6. Boventre, P. F., and Kempe, L. L. (1960), "Physiology of
Toxin Production by Clostriduum Botulinum types A and
B.I. Growth, autolysis, and toxin production," J. Bacteriol.
Vol. 79, pp. 18-23.
7. Brunner, D. R., and Kellar, D. J. (1972), Sanitary Landfill,
Design and Operations, US EPA Report No. Sw-65ts.
8. Burchinal, J. C„ and Qasim, S. R. (1970), "Leaching of
Pollutants from Refuse Beds," JSED, ASCE, Vol. 96
(SA1), pp. 49-58.
-------
180 Disinfection
Table II: API 20E Results of Influent 1 (Leachate + Tap Water)
|Strip|
no.
API
Profile
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
First Choice
1 504 573
3 304 573
1 304 573
5 315 773
1 104 573
7 305 773
2 216 002
4 306 002
7 757 777
5 355 773
5 356 773
5 357 773
5 217 773
5 115 112
5 315 773
5 104 773
5 114 142
0 004 042
1 004 123
2 306 042
0 044 002
4 004 102
0 044 112
6 006 002
6 104 112
2 124 002
0 014 112
2 004 502
2 004 102
0 004 012
6 104 112
Cit. freundii
Ent. cloacae
Cit.freundii
Ent.Aerogenes
Cit.freundii
Ent.cloacae
Ps .Aeroginosa
Second Choice
E. coli
Cit.freundii
Ent.cloacae
Kl.pneumoniae
E. coli
Ser.liquefaciens
Chromobacterium
Kl.pneumoniae Ser.liquefaciens
XI .pneumoniae
Ent.hafniae
Ent.aerogenes
Ent.aerogenes
Acin.calcoac.
Ent.agglom.
Ser.liquefaciens
Kl. ozaenae
Kl.pneumoniae
Ser. liquefaciens
Sh.flexneri
Ser.rubidoea
Third Choice
Sh.dyscnteria
Sal.entcritidi^
E. Coli
Ent.hafniae
Y. pseudo.
E. coli
E. coli
Ent.hafniae
E. coli
|e. coli
Sh. flexneri
Sal.enteritidis
Sal.enteritidis !
Sh. boydii
Sh. boydii
Sal.enteritidis
Ser.liquefaciens
Cit.diversus
Ser.liqucfaciens
Ser.liquefaciens
Ser.liquefaciens
Ent.aerogenes
Prot.mirabili*
Ent.aerogenes
Ent.aerogenes
Ser.liquefaciens
Ser.liquefaciens
Kl. ozaenae
Sh.boydii
Kl .ozaenae
Sh. flexneri
Ent.hafniae
Sh. dysentcriae
Sal.enteritidis 6
Kl. ozaenae
Cit.freundii
Sh. flexneri
Sal.enteritidis 6
-i - — _
The rest of API strips had either same profile numbers as
the foregoings or no identification.
- ¦ no identification * the profile number does not fit the
Cit
E. '
Ser
Ent
Kl-
PS .
index
« Citrobacter
Escherichia
• Serrattia
« Enterobacter
> Klebsiella
¦ pscudomonas
Prot. - Proteus
Acin. * Acinetobacter
Sh. - Shigella
Sal. • Salmonella
y. • yersinia
9. Chick, H. (1908), "Investigation of the Laws of Disinfec-
tion," J. Hygiene, Vol. 8, p. 698.
10. Cooper, R. C., Potter, J. L. and Leong, C. (1974), "Virus
Survival in Solid Waste Treatment System," in Virus
Survival in Water and Wastewater Systems, J. D. Malina
and B. P. Sagik (eds.), Water Res. Sym. No. 7, Center for
Research in Water Resources, The Univ. of Texas at
Austin, pp. 218-240.
11. Culham, W. B. and McHugh, R. A.(1969),"Leachatefrom
Landfills may be New Pollutant," J¦ of Environmental
Health, Vol. 31, No. 6, pp. 551-556, May/June.
12. Doermann, A. H. (1976), The Genetics Department,
University of Washington, Setattle, Wa (personal commun-
ication).
15.
16.
17
18.
20.
21.
13. Engelbrecht, R.S. and Atnirhor, P. (1975), "Biological
Impact of Sanitary Landfill Leachate on the Environment,"
Paper presented at the Second National Conference on
Complete Water Reuse, AlChE and EPA: Technology
Transfer, Chicago, Illinois, May 4 8.
14. EPA, Technology Transfer (1974), Methods for Chemical
Analvsis of Water and Wastes, Washington, D.C.
Finger, R. E. (1975), Water Quality Analyst, Municipality
of Metropolitan Seattle, (personal communication).
Gerba, C. P., Wallis, C., and Melnick, J. L. (1975),"Fate of
Wastewater Bacteria and Viruses in Soil," J. Irrigation and
Drainage Div., ASCE, Vol. 101, No. IE3, pp. 156-174,
September.
Klein, S. A. and others (1972),"Environmental Evaluation
of Disposable Diapers, "Sanitary Engineering Research
Laboratory, SERL Report No. 72-1, Univ. of California,
Berkeley.
Lauria, S. E. (1947), "Reactivation of Irradiated Bacterio-
phage by Transfer of Self-Reproducing Units," Proc. Natl.
Academy of Sciences, Vol. 33, No. 9, pp. 253 264.
19. Millipore (1973), Biological Analysis of Water and Waste-
water, Application Manual AM302, Millipore Corp.,
Bedford, MA.
Morris, J. C., and Wei, J- H. (1973), "Dynamics of
Breakpoint Chlorination," Proc. Chemical Society, Dallas,
Texas, pp. 125-132.
Plotkin, S. A. and Katz, M. (1965), "Minimal Infective
Doses of V iruses for Man by the Oral R oute," G. Berg(ed.),
Transmission of Viruses by the Water Route, Interscience
Publisher, New York, pp. 151-166.
22. Pritchard, R. R. (1976), "Some Effects of Chlorinating
Leachate," MS Thesis, University of Washington, Seattle,
Wa.
Polprasert, C. (1976), "Disinfection of Treated Landfill
Leachate Using Sodium Hypochlorite," Ph.D. Thesis,
University of Washington, Seattle, Wa.
Reid, L. C., Jr., and Carlson, D. A. (1974), "Chlorine
Disinfection of Low Temperature Waters," JSED, ASCE,
Vol. 100, No. EE2, Proc. Paper 10443, pp. 339- 351.
Riley, R. D. (1973), "Some Bacterial and Chemical Charac-
teristics of Leachate Water from a Sanitary Landfill," M.S.
Thesis, University of Washington, Seattle, Wa.
Saunier, B., and Selleck, R. E. (1976), "Kinetics of Break-
point Chlorination and of Disinfection," SERL Report
76-2, Univ. of Calif., Berkeley.
Schaub, S. A. and Sagik, B. P. (1975), "Association of
Enteroviruses with Natural and Artificially Introduced
Colloidal Solids in Water and Infectivity of Solids-
Associated Virions," Appl. Microbiol., Vol. 30, No. 2, pp.
212-222, August.
28. Sobsey, M. D., Wallis, C., and Melnick, J. L., (1974a)
"Enteric Viruses in Municipal Solid Waste Landfill and
Leachate," Internal Report to Procter and Gamble, Co.,
Cincinnati, Ohio, as reported by Engelbrecht and Amirhor
(1975).
29. Sobsey, M. D., Wallis, C., and Melnick, J. L.(1974b),"De-
velopment of Methods for Detecting V iruses in Solid Waste
Landfill Leachate," Applied Micro., Vol. 28, No. 2, pp.
232-238
30. Sobsey, M. D., Wallis, C„ and Melnick, J. L. (1975),
"Studies on the Survival and Fate of Enteroviruses in an
Experimental Model of a Municipal Solid Waste Landfill
and Leachate," Appl. Microbiol¦> Vol. 30, No. 4, pp.
565-574.
31. USPHS (1965), Preliminary Data Analysis, 1968 National
Survey of Community Solid Waste Practices, Publ. no.
1867, Cincinnati, Ohio.
32. Vasconcelos, G. J. (1974), Microbiologist, U.S. EPA
Region X Laboratory (Internal Report).
23.
24.
25.
26.
27.
-------
Disinfection 181
N/N
ro
cr
to
>
•r*
>
3
t/>
NaOCl Dosage, mg/1-
10"
Dosage, mg/1 NaOCl Actual Slope
25
40
48
55
-0.30
-0.64
-0.75
-1.09
nh3/ci2
(Weight Ratio)
1/6.62
1/10.59
1/12.70
1/14.56
Beyond Breakpoint Chiorination,
mg/1 NaOCl
pH - 7.4
COD- 150 mg/1
SS - 43 mg/1
NH^N - 1.8 mg/1
Hardness(EDTA) - 430 mg/1
(Plotted by Least Squares Method)
_L
J
10
20
30 60 100
Contact Time. min.
Figure 2: Summary of T-4 Virus Chlorination in Effluent E-l (Mean + 95% Confidence Limits) Initial Viral Densities (N0)= 69* 106 -
1*107 PFU/ml
-------
182 Disinfection
N/N
to
cc
tS)
10
-6
(Plotted by Least Squares Method)
NH3/C12
mg/1 NaOCl
Actual Slope
(Weiqht Ratio)
5
-0.47
1/1.32
10
-1.69
1/2.64
15
-2.27
1/3.97
20
-2.70
1/5.29
1
2
10
20 30 60 100
Contact Tirce, minutes
Figure 3: Summary of Chlorination of Coliforms in Effluent E-l (Mean + 95% Confidence Limits) Initial Bacterial Densities (N0) =
34*I0<> 16* 107 CFU/ml
-------
Disinfection, 183
nH - 7.4 - 7.6
COD - 160 mq/1
SS - 55 mq/1
NH^-N = 3.7 mn/1
Hardness (EDTA) = 340 mg/1
52.5
20 30 60
Contact Time, min.
Figure 4: Summary of T-4 Virus Chlorination in Effluent E-2
(Mean + 95% Confidence Limits)
Initial Viral Densities (N0) = 12" 107 - 33" 107 PFU/ml
-3 h
10
10"
-6
(Plotted t>v Least Squares
Dosaqe, mq/1
Actual
nh3/ci?
NaOCl
SI one
(Weinht Ratio)
5
-2.00
1/0*64
7.5
-3.03
1/0.96
10
-4.54
1/1.28
13
-4.76
1/1.67
10
20 30 60 100
Contact Time, min.
Figure 5: Summary of Chlorination of Coliforms in Effluent E-2
(Mean + 95% Confidence Limits)
Initial Bacterial Densities (N0) = 49* 105 15" 107 CFU/ml
EuTA Hardness, mg/l as CaCO,
1000 mq/1 aa CaC03
O
ao jo co ioo
Cootact T1m. ain.
Figure 6: Chlorination of T-4 Virus at Different Hardness
Concentrations (Effluent E-l)
10
N/H
Total Hardness
000 mq/1 as CaCOj
30 CO 100
Contact Ti»a, min.
Figure 7: Chlorination of Total Coliform at Different Hardness
Concentrations (Effluent E-l)
-------
184 Disinfection
N/N,
10
-1
cc
<0
>
>
u
in
Ik
10
-2
s
\ 4
5 mg/1 NaOCl
$
\
v.
\
10
-3
O
A
Data for 5 mg/1 NaOCl
Data for 20 mg/1 NaOCl
I
U
\
\
20 mg
n NaOC
X a
N.
\
S
a s
i i
10
-4
\
1
\
N
\
N
— Predicted Survival Ratios And Their Ranges
According to Eqn. 5
\
s
a
i i
10'
dN
at
-2.26 x 10"7.N1,56.C2,28
(5)
A
10
-6
10
20 30 60
Contact Time, minutes
Figure 8: Comparison Between Experimental and Predicted Data for Chlorination of Coliforms in Effluent E-l.
-------
Disinfection
N/N
10'
(\3
fO
>
•r—
>
S-
3
CO
10
-2
10
-3
10"
O
I-
10"
A
A
A
A
NaOCl = 52.5 mg/1
N
\
\ ^°C;
O
tJT
^ fa
N %/; a
x
\
^-9
4
K*a
A
A
A
A
'O
«s»
S
w
s
\
A V/
S.
\
1 U
s
N.
n
\
Cb,
*
4>,
A
A
A
A %
stt
&
O
1h
A
~
A
o
o
~
A
Data for 52.5 mg/1 NaOCl
Data for 79 mg/1 NaOCl
Data for 105 mg/1 NaOCl
Data for 137 mg/1 NaOCl
o/.,
A
A
}v
10
-6
¦Predicted Survival Ratios and
Their Ranges According to Eqn.7
dN
dt
-5.08 x 10'13.N1,72.C3-66
A
A
(7)
10
-7
10
20 30 60
Contact Time, min.
Figure 9: Comparison Between Experimental and Predicted Data for T-4 Virus Chlorination in Effluent E-2.
-------
186 Disinfection
, 10 100 1,000 10,000
C't, mg NaOCl - min/1
Figure 10: Relationships between Organisms Survival Ratios vs. C • t in Effluent E-I.
-------
Disinfection 187
APPENDIX A
Some characteristics of Raw Leachate from the Cedar Hills
Sanitary Landfill, and Influents and Effluents of the Laboratory
Activated Sludge Units. All constituents expressed as mg/1
except pH which is unitless.
Parameter
?aw Leachate
Influent 1
Leachate +
Tap water
Effluent E-l
(1.1 +1.2)
Influent 2
Leachate +
Prim.Sewage
Effluent 2
(2.1 +2.2)
COD,
unfilterec
9,680
5,980
820
5,920
660
PH
5.0
5.6
7.6
5.7
7.6
D.O.
0
3
-
3
-
ss
8,860
3,210
180
4,370
130
NH3-N
295.0
11.5
4.9
10.5
6.6
Total-P
67.5
16.5
2.2
22.0
1.7
Total Volatile*
Organic Acids
7,300
4,180
370
3,680
340
Pb*
0.03-23.35
-
-
-
-
Fe#
250-2,115
-
-
-
-
In
1.2-149
-
-
-
* Excluding Formic and Caproic Acids
» Data Provided by Finger (1975)
- Not Avai Table
-------
Development of Standardized
Procedures for
Leachate Generation
H. I. Abelson, W. C. Lowenbach and
F. Ellerbusch
METREK, A Division of the
MITRE Corporation
Concord, Massachusetts
INTRODUCTION
I 1 V V, * . „ - ,
Each year, about 2.8 billion tons of solid waste are generated
in the United States. An 8 percent annual increase in the volume
of such waste is anticipated. Of this total, 260 million tons
originate from industrial sources. Disposal of solid wastes,
including hazardous materials, can have adverse environ-
mental impact in various ways. Perhaps the most pernicious
effect is the contamination of ground and surface waters by
leachate resulting from land and subsurface disposal. About
half of the U.S. domestic water supply originates from under-
ground sources and thus, is potentially subject to
contamination.
The potential for leaching exists whenever water (or any other
eluant) comes into direct contact with a solid. Leachate may be
defined as a liquid which, through contact with a solid material,
has extracted constituents from it. As a result of the flow over
and through the material, the leachate may, in addition, contain
suspended solid matter. Certain constituents of a mterial may be
readily soluble in the eluant liquid while others are solubilized
by the action of leachate generated "upstream." Experience also
indicates that while some materials may initially release only
small amounts of contaminants, under extended leaching
conditions, they will release much higher concentrations.
Transport of leachate occurs via two mechanisms: runoff and
percolation. Runoff (i.e., overland flow) is typically character-
ized by relatively high flow rates, as governed by site topo-
graphy, and short liquid-solid contact times (hours, or at most, a
few days). Runoff, in addition, represents the principal trans-
port mode for suspended solids. Percolation through porous
media, on the other hand, is characterized by significantly lower
flow rates (as governed by material permeability) and much
longer liquid-solid contact periods. Species transport by this
mode occurs primarily in solution.
Leachate generated from land and subsurface disposal of
industrial wastes may be transported to ground and surface
waters via both of the above modes, singularly or in combina-
tion. Percolation of leachate through media surrounding a
disposal site, however, is more insidious and more difficult to
control. Although the principal contributor to leachate genera-
tion is precipitation, other contributors can include infiltration
of ground and/ or surface waters into the site as well as the ini-
tial moisture content of the waste material itself.
Present management of land and subsurface disposal of
industrial wastes is frequently inadequate. Significant environ-
mental impacts from such activities are not mere possibilities—
actual damages to groundwater have occurred and are well
documented. A case in point involves an incident that occurred
several years ago in Minnesota in which eleven persons devel-
oped arsenic poisoning as a result of drinking water from a
contaminated well. Analysis of water samples established
arsenic concentrations of up to 21,000 ppb (the U.S. P.H.S.
drinking water standard is 50 ppb). The source of contamination
was traced to the burial of less than 50 pounds of grasshopper
bait (arsenic trioxide) back in the mid-1930's in the vicinity of
where the well was later drilled. Based on cases such as this, it is
clear that a great need exists for standards on which to base
controls for the disposal of waste materials.
Recently, the Solid Waste Disposal Act of 1976 (Public Law
94 5X0) has been passed by Congress to address this issue. As
part of this legislation, the EPA Office of Solid Waste Manage-
ment Programs has the responsibility to develop and publish,
within eighteen months, suggested guidelines for solid waste
management, including the protection of ground and surface
waters from leachates. In support of interim guideline devel-
opment, there exists a need for a standardized laboratory
leachate test that would assess potential contaminant release
from industrial solid waste.
The MITRE Corporation is presently assisting
EPA/OSWMP in the development of an interim standardized
leachate test. The purpose of the present paper is to briefly
survey available leachate assessment techniques and to discuss
relevant test design parameters that should be given consid-
eration in the development of standardized procedures. In
particular, attention is focused on the relation between test
parameters and actual conditions at a disposal site.
Basic Test Types
Leachate assessment techniques may be classified into three
categories: the shake test, the column test, and the field test cell.
The MITRE Corporation has perfomred a state-of-the-art
survey of techniques employed by various governmental,
industrial, and academic institutions. A compilation of this
data, including descriptions of numerous test variations within
these three categories, is provided in a recently published
document* Additional references on leaching and leachate
assessment can be found therein.
Briefly, the shake test (or elutriate test) is performed by
agitating a solid sample with an eluant for a specified period of
time and subsequently analyzing the filtrate. The test is rela-
tively rapid, simple, inexpensive to perform, and uses commonly
available equipment. The procedure does not, however, provide
results which can be readily interpreted as steady state or rate
related data. Furthermore, the relationship between environ-
mental factors which control leaching at a disposal site and
shake test design parameters is difficult to establish. The shake
test is strictly a leachate generation procedure and cannot be
188
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aianuaraizea rroceaures isv
employed for related studies such as evaluating the attenuation
capabilities of soil surrounding a disposal site. It is considered
by some to produce a "worst case" leachate (i.e., the maximum
concentrations at which pollutants are likely to be released to
the environment). Test design parameters relevant to the shake
test are addressed in a later section.
The most widely employed leachate assessment method is the
column test. The basic technique involves placing a sample of
solid material inside a hollow, cylindrical, vertical column and
allowing an eluant to infiltrate and percolate through the
sample. The leachate is collected and subsequently analyzed.
Many variations of the column test have been reported. In its
simplest form, the method is inexpensive and utilizes commonly
available equipment. The test, if carefully designed and inter-
preted, can provide rate-related data on pollutant release. Test
durations are generally long (months to years) because column
flow rates simulate the very low percolation rates characteristic
of actual disposal site environments. The relationship between
environmental factors which control leaching at a site and test
design parameters, although somewhat better defined than for
the shake test, still remains difficult to establish. The column
technique, in addition to being employed as a leachate genera-
tion procedure, may also be utilized for studying the attenuation
(i.e., ion exchange, absorption, etc.) capabilities of soils sur-
rounding a disposal site. Design parameters of the column test
are discussed in the following section.
The field test cell, the third category of leachate testing
methods, is, as the name implies, a field rather than a laboratory
technique. Cell designs range from large in-ground columns to
scaled-down landfill sites. The obvious advantage of a field
method is that leachate is generated under natural conditions. In
addition, impacts on groundwater quality, the effectiveness of
liners, and attenuation by surrounding soils can be measured
directly. Field test cells are, however, expensive to construct and
monitor. Furthermore, testing periods are typically on the order
of years. Since the development of a standardized laboratory
procedure for leachate generation is of prime concern here, no
further consideration will be given to field test cells.
Test Design Parameters
Defining and adjusting laboratory test parameters to simulate
the natural conditions under which leachate is produced repre-
sents one of the most important considerations in the devel-
opment of standardized procedures for leachate generation.
This is true whether the shake or column method is employed.
Although the attributes and drawbacks of each of these
techniques were described earlier, no recommendation will be
made here regarding which technique should be used for a stan-
dardized procedure. The purpose of this section is, instead, to
discuss design parameters that are relevant to both the shake
and column methods.
One of the most important factors controlling the leaching
mechanism is eluant composition. Land disposal waste mate-
rials may be leached by direct precipitation, by surface runoff
generated by precipitation, and by groundwater. Characteristics
of natural eluts may in many cases be difficult to assess and to re-
produce in the laboratory. The following parameters, however,
are significant to defining eluant composition and characteris-
tics:
pH
The pH of rainwateriscontrolledprimarilybydissolvedC02.
Surface and groundwater pH is governed by additional factors,
particularly the history of their contact with solids.
•Procedures Manual for Environmental Assessment of Fluidized-Bed
Combustion Processes (Chapter 4). EPA 600/7-77-009. January 1977.
Total Acidity I Alkalinity
Total acidity/alkalinity together with pH define the buffering
capacity of the eluant. Natural eluants are likely to be buffered.
A wide variety of buffers is possible and a particular system must
be selected with care.
Dielectric Constant
The dielectric constant is related to the solvating power of the
eluant and increases with the addition of ionic species. Polar
substances become more soluble with increasing dielectric
constant while the reverse is true of non-polar substances. For
natural eluants, the value of this constant is a function of
dissolved species and may be difficult to reproduce in the
laboratory.
Eh (Aerobicity)
Eh is the oxidative or reductive capacity of the eluant and
provides a frame of reference within which redox and hyd rolysis
reactions of different metals may be compared. The Eh value is a
function of pH and is related to dissolved oxygen concentration.
The aerobic or anaerobic conditions under which a material
may be leached is defined in part by Eh. For rainwater, typical
Eh values range from 0.4 to 0.6 volts. Air must be excluded from
a shake test vessel or column to maintain anaerobic conditions
(i.e., negative Eh values).
Organic Constituents
Organic constituents effect the complexing ability of an
eluant and may react with waste to produce new pollutants.
Organic constituents in natural eluants occur through surface
runoff and percolation through soils. Individual organic com-
pounds within a natural eluant may be difficult to identify and
measure.
Another parameter of primary importance is temperature.
Reaction rates and the solubility of potentially leached materials
are affected significantly by temperature changes. The control of
temperature in a laboratory test (shake or column) is essential
for simulating natural conditions and insuring reproducibility.
It should be noted that ambient temperatures within a waste
disposal site may vary widely, and incorporation of such
variations into a laboratory test is not generally possible.
The test parameters discussed so far are relevant to both the
shake and column methods. The following list of parameters is
specific only to the design of a shake test.
Liquid-to- Solid Ratio
By increasing the liquid-to-solid ratio, saturation equilibria
effects (e.g., common ion effect) may be minimized; species
which would normally appear in the leachate only after long
periods of time may be detected and measured. The ratio at
which saturation effects no longer completely supress the most
insoluble species can be ascertained by progressively increasing
the eluant volume (using a new solid sample) and analyzing the
filtrate. The shake method does not generally provide useful
data relating to the quantity of leachate generated as a disposal
site.
Test Duration
Agitation should be terminated when filtrate analysis indi-
cates that equilibrium has been reached (i.e., no significant
concentration changes). Kinetic data can be obtained by
frequent sampling intervals. Typical test durations are 24, 48,
72, and 96 hours although values as low as 1 hour and as high as
10 days have been reported.
Particle Size
Dissolution of a solid is limited in part by the surface area of
-------
190 Standardized Procedures
the solid. Increasing surface area of a sample by grinding will
increase dissolution rates. Equilibration within the system is
reached sooner and test duration is accordingly shortened. Size
reduction is a physical process and therefore does not affect the
overall leaching mechanism. (It can however lead to an overesti-
mation of pollutant release rates.)
Agitation Method
Shaking (with a wrist action shaker) or stirring are commonly
employed agitation methods. Compressed gas agitation is useful
for control of aerobic or anaerobic conditions. Aerobic condi-
tions may be simulated by 02 or air agitation; anaerobic
conditions may be simulated using an inert gas.
Eluant Cycles
In this variation of the shake test, saturated eluant may be
filtered from the solid and fresh eluant added to the system. The
process may be repeated several times until a steady-state
condition is reached and is designed to represent time depen-
dent release of pollutants. The parameters that follow are
relevant to the design of a column test only.
Flow Rale
Control of flow rate within a column to simulate field
percolation rates and insure reproducibility represents one of
the most important aspects of column test design. Estimation of
field percolation rates is difficult in most cases. Low flow rates
will result in long-time intervals for column leachate collection.
Column tests are designed to employ either a constant head or
a falling head. In the former method, a constant eluant level is
maintained above the top of the sample, producing a constant
flow rate (provided flow resistance does not change). In the
easier-to-construct falling head system, a specified quantity of
eluant is added to the column and the level is allowed to drop.
This process may be repeated several times to achieve a given
total flow through the column. As the eluant level decreases, the
flow rate decreases (assuming no changes in flow resistance).
For "solid block" type samples (e.g., chemically fixed sludges)
of very low permeability, a column arrangement has been
reported in which the annular space between the column and the
sample is filled with a packing such as glass beads. This
simulates the more permeable surrounding media and the
'•surface bathing" of the sample. In normal column tests, the
annual space is eliminated (or scaled) to prevent How bypass and
permit only percolative flow.
Sample Compaction
f low rate through a porous medium is a tunction of
permeability which is dependent, in part, on degree of
compaction. Compaction and permeability ot a laboratory
column sample should simulate field conditions as closely as
possible.
Total Eluant Volume
Once a How rate has been selected, the total volume of eluant
passing through the column will determine the test duration. In
many reported cases, the test was terminated when equilibrium
was attained. In other cases, total eluant volume was selected to
simulate actual rainfall quantities. In some tests, the total vol-
ume values were chosen to insure adequate leachate samples for
analysis.
Particle I Column Diameter Ratio
For column flow to be representative of flow through much
larger volumes (e.g., solid waste), the ratio of average particle
equivalent diameter to column diameter should not be too large.
For instance, a sample with an average particle diamter of 2
inches would not he placed in a 4-inch diameter column. Size
reduction of a sample may be required. This consideration is of
most concern when dealing with non-homogeneous waste
materials such as municipal refuse and of little concern with fine
granular materials.
SUMMARY
In this paper, an attempt has been made to survey the various
techniques available for leachate generation and to discuss
significant parameters associated with these techniques. It
should be noted that efforts by EPA (as well as ASTM) towards
development of standardized leachate generation procedures
have recently begun. Accomplishment of standardization will
require a more detailed look at the techniques and parameters
discussed here as well as a clear definition of the desired
characteristics of a standardized procedure. Input from all
interested parties would be most valuable.
-------
Land Cultivation of
Industrial Wastewaters
and Sludges H. T. Phung and D. E. Ross
SCS Engineers, Inc.
Long Beach, California
and
R. E. Landreth
U.S. Environmental Protection Agency
Cincinnati, Ohio
INTRODUCTION
The disposal of industrial wastes presents problems to the
waste generator and/or disposal site operator. Many industrial
wastes are very complex and are generated in large volumes.
Moreover, industrial waste disposal problems are expected to
increase due to the continuing energy crisis, requirements for
increased pretreatment of wastewaters, and more stringent
water pollution control regulations controlling the disposal of
effluents and sludges to water bodies. Thus, there has been
intensified interest in the application of wastewaters and sludges
to land and the development of alternative land disposal
techniques.
Industrial wastes are typically disposed of in sanitary landfills
or deep wells orare incinerated19. Someare recycled, stockpiled,
or simply dumped into the ocean. Hazardous industrial wastes
are primarily in liquid or semi-liquid (sludge) form. Incidents of
air, ground, and surface water pollution from improper land
disposal of these wastes have been reported7. Lehman* con-
cluded that the technology for adequate waste management
exists, but that this technology is costly (approximately 10 to 20
times as expensive as currently unacceptable practices such as
land dumping or ocean disposal).
The land cultivation method of industrial waste disposal is
more widely practiced. However, very little published data are
available on this method and its potential environmental
impacts. Moreover, because of their diverse chemical and
physical natures, each industrial waste has to be considered and
evaluated on an individual basis. Accordingly, the U.S.
Environmental Protection Agency, Solid and Hazardous Waste
Research Division, Municipal Environmental Research Labor-
atory is sponsoring a comprehensive study of land cultivation
practices. Basic project objectives include:
• Gathering and assessing available information relating to
past, existing, and planned disposal activities involving
land cultivation of industrial wastewaters and sludges;
• Evaluating pertinent technical, operational, economic, and
environmental factors; and
• Determining the chemical composition and uptake of
heavy metals and toxic constituents by plants growing on
selected disposal sites where land cultivation is practiced.
The project is currently underway and is scheduled for
completion by December 1977. This paper presents a progress
report reflecting findings of the literature review, personal
interviews, and field investigations to date. Results obtained
from the five land cultivation case study sites are not reported,
since data are incomplete. This paper is concerned mainly with
industrial waste land cultivation. A companion paper on land
cultivation of municipal solid waste has been presented else-
where16.
Land Cultivation—A Waste Management Alterna-
tive
Soil, through complex physical, physio-chemical, chemical,
and microbiological processes, is a natural environment for the
deactivation and degradation of many waste materials15. The
land cultivation of waste is a disposal technique by which waste
products are mixed with the soil to promote these processes,
particularly microbial decomposition of the organic fraction.
This practice is also known by other names; landspreading, soil
incorporation, and land farming. If managed properly for some
waste materials, the process could, be carried out repeatedly at a
given site. Proponents of land cultivation claim that, under ideal
conditions, a site could be returned to any other land use after
cessation of disposal activities. At some sites, agronomic crops
are grown during the waste utilization operation.
Although ideal conditions are rarely met in the field, and
literature on the environmental impacts, regulatory controls,
and waste types and characteristics is scarce, the practice of land
cultivation has such promise and has had enough preliminary
success that many industries are already land cultivating their
wastes or are planning to do so.
The suitability of an industrial waste for land cultivation will
depend on such characteristics as: concentrations of chemical
elements in soluble as well as insoluble forms; bulk densities of
waste solids; BOD, pH, sodium, and soluble salt contents; as
well as inflammability and volatility4'1*-20. Local climatic
conditions can also influence the viability of this waste manage-
ment practice. For example, land cultivation activities are
usually curtailed, when the soil is excessively wet or frozen. The
presence of vegetative cover too can significantly benefit the
waste management practice through erosion control and the
uptake of nutrients and water. To some extent, the Irrigation
Water Quality Criteria12 and existing proposed guidelines of
heavy metal loading for sewage sludges can be used to determine
the suitability of industrial wastewaters and sludges for land
cultivation4.
Land Cultivation of Industrial Wastewaters
Land cultivation of wastewaters from food processing, pulp
and paper, textile, tannery, and pharmaceutical industries has
been practiced on a limited scale18'20, primarily as a wastewater
treatment method, with little or no attention paid to soil
incorporation. Moreover, crop production is of secondary
importance.
Commonly, three application techniques are used: surface
irrigation, overland flow, or rapid infiltration5.18. Which proce-
191
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192 I.and Cultivation
dure is selected depends, in various degrees, on such site specific
factors as topography, soil texture, land size, and cover crop. At
this time, surface irrigation is used most extensively and offers
the highest degree of disposal reliability and potential for long-
term usage. Overland flow may require operational manipula-
tions to realize the same useful site life as surface irrigation.
Rapid infiltration (groundwater recharge) will require the most
extensive and thorough site investigations, to ensure that
favorable conditions exist. Examples of industries utilizing
these application systems1* as well as by hydraulic and organic
loading rates in existing land treatment sites2" have been cited.
Land Cultivation of Industrial Sludges
Information gathered indicates that industrial sludges appli-
cable to land cultivation have been either organic (e.g., oil
refinery, paper and pulp, and fermentation residues), or treated
inorganic (e.g., steel mill sludge) wastes containing insignificant
levels of extractable heavy metals. When such waste is applied to
agricultural land, it is generally used as a soil amendment (to
improve soil characteristics) and/ or low-analysis nitrogen fertil-
izer.
In actual field disposal operations, sludges are either hauled
directly from the wastewater treatment plant or a lagoon to the
disposal site. The sludges are applied to the land by spraying,
spreading, or subsurface injection. The field is then disked or
plowed by conventional farm cultivation equipment. Loading
rates generally depend on BOD, total dissolved solids, and
soluble salt contents of the waste and the texture and drainage
characteristics of the soil. Presently, state regulations do not
limit the concentration of heavy metals or other potentially
toxic constituents that are present at varying amounts in the
sludges. Increased regulation will likely occur, if land cultivation
becomes more common.
Among industrial sludges, oil refinery wastes have been
extensively disposed of by land cultivation6'10. Oil degradation
rates vary depending on climate, oil content of the soil, and
fertilization. Oily sludges that are disposed of by land cultiva-
tion include cleanings from crude oil, slop emulsion, API
separator bottoms, drilling muds, and other cleaning residues10
The sludge is spread to a depth of about 8 to 15 cm by a track-
dozer and then disked into the soil, with mixing at weekly or
monthly intervals. This technique is strictly for disposal of
wastes; no crops or vegetation are purposely grown at such sites.
Limited data are available from greenhouse and field investi-
gations evaluating the potential adverse effects of application of
some industrial sludges on the yield and quality of crops.
DeRoo' assessed mycelial sludges produced by the
pharmaceutical industry in Connecticut as a nitrogen fertilizer
and organic soil amendment. He concluded that if the mycelial
sludge is applied repeatedly at high rates (222 mt/ ha) to the same
field, the soluble salt concentration and high zinc content in the
sludge may be injurious to plants. Similar studies have been
conducted using lagooned paper pulp (Jacobs, personal
communication), cannery fruit and nylon sludges (Cotnoir,
personal communication). Results indicated that these sludges
would have value as a low-analysis nitrogen fertilizer; no
adverse effects were observed in crops and soils.
In field studies, the effects of refractory metal processing17
and steel mill sludges (Nelson, personal communication) on the
yield and chemical composition of forage and grain crops were
evaluated. No adverse effects from heavy metals were observed,
although in the case of steel mill sludge, the growth was stunted
at high waste application rates (sludge about 20 cm thick). This
was attributed to nitrogen and phosphorus deficiencies induced
by waste application and poor aeration from soil compaction.
It is recognized that soil can often serve as an effective
disposal sink for industrial organic wastewater and sludge.
However, if a specific soil cannot assimilate the applied quantity
of organic sludge, the soil will become anaerobic, resulting in
nuisance conditions and failure of the system. Moreover, unless
the waste materials arc detoxified or decomposed by the soil or
weather to nondeleterious products, the upper soil zone receiv-
ing the wastes eventually wil1 become loaded to its ultimate
capacity. As a result, disposal activities at the site will have to be
terminated.
Environmental Assessment
Data on environmental pollution resulting from land cultiva-
tion of industrial wastewaters and sludges are very scarce. It is
recognized that improper land disposal of industrial wastes
often goes unnoticed in the short-term, because the impacts
occur over a long period of time and are chronic, rather than
acute7. Phillips and Nathwani15 have recently reviewed the
various mechanisms involved in soil-waste interactions. The
migration of heavy metals and toxic organic compounds into
the groundwater, surface run-off, air pollution, and potential
hazards to the food chain are of especial concern.
Water Quality
In any land application practice, there is always a risk of
contaminating subsurface waters. Adriano, et aU presented
data showing that th nitrate and phosphate levels in subsurface
waters exceeded public health standards and environmental
guidelines, respectively, from long-term land treatment of food
processing wastewaters.
The downward movement of heavy metals, oils, and organic
chemicals in soils is often restricted due to low water solubility
and high retention and degradation by various soil pro-
cesses14'1"'''. Various chlorinated hydrocarbons, phenols, and
detergent components may be present in varying amounts in the
wastes, depending to a large degree on the type of generator
industry. It is believed that these organic compounds will
eventually be decomposed by soil microorganisms, and unless
the soil is overloaded with wastes containing large amounts of
these substances, land cultivation is not likely to pose a serious
threat to the groundwater quality.
Most land cultivation sites have berms or dikes for erosion
control. This is important, since movement of agricultural
chemicals in runoff has been a major source of surface water
contamination in downstream areas of farming communities.
K-incannon6 reported oil contents of 30 100 mg/1 in the run-off
rainwater from an oily waste landform; most of the organic
acids in the rainwater had characteristics similar to napthenic
acids.
Air Emissions
When exposed to the atmosphere, industrial wastewaters and
sludges emanate odors and thus impair the air quality at the
disposal site. If the waste contains volatile components, land
cultivation practices could increase evaporation of these compo-
nents. Additionally, during soil incorporation, dust could
present a health hazard to personnel on the site. Subsurface
injection of the waste and/or mixing with soil as soon as
1 practical after deposition can alleviate, but not always eliminate
odor and evaporation problems.
Hazards to the Food Chain
In on-going instances of land treatment of industrial waste-
water, a cover crop is generally regarded as an integral part of
the system, since it will improve water infiltration, remove
nutrients, and increase evapotranspiration loss. In land cultiva-
tion of industrial sludge, existing vegetation is usually removed
from the site before waste application. Seeded crops or Weeds
will become established in the disposal plot only if the plot is
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Land Cultivation 193
unfilled for some time. Available information indicates that
crops grown on agricultural soils treated with selected industrial
wastewaters and sludges do not accumulate significant quanti-
ties of toxic metals to adversely affect plant growth1, and
Nelson, Jacobs, and Cotnoir, personal communications.
However, long-term effects of land cultivation on crop quality
and the food chain are not known.
Through surface contamination and plant uptake, land
cultivation of waste material can pose hazards to the food chain.
Pesticide residues (e.g., DDT) have been shown to accumulate
in various root crops1renderingthem unsafe forconsumption.
Chancy2 briefly discussed the effects of toxic elements in
sewage sludges and effluents on the food chain. He listed Cd,
Cu, and Zn as the elements posing significant potential hazards
through plant accumulation. However, it should be noted,
under improper site management (overloading, low pH, etc.),
elements such as Pb, Hg, As, Se, Mo, and Ni, if present in
significant quantities in the wastes that are land cultivated,
could also pose serious hazards to both man and animals
consuming the crops.
Vegetative Impacts
As part of this study, composite samples of surface soil (0-15
cm) and typical native vegetation were taken from two oily
waste disposal sites as well as from the corresponding control
sites which had similar soil and vegetation but had received no
waste. The objective was to determine the effect of land
cultivation of oily sludges on soil chemical properties and
elemental uptake. Pertinent information on the two sites studied
is presented in Table 1. Note that site age, soil, and sludge
characteristics from the two sites are markedly different. Site A
is managed by a disposal company, while site B is located within
and managed by an oil refinery plant.
Land cultivation of oily wastes at site A resulted in increased
pH, soluble salt content (expressed as EC), and levels of total
Kjeldahl nitrogen (TK.N) and organic carbon in the sandy soil
(Table 11). Likewise, water-soluble B and acid-extractable Na,
Mn, Ni, Zn, Se, and Pb also increased. At site B, similar
increases were noted for soluble salts, TK.N, organic carbon, and
acid-extractable Na, Mn, Zn, Se, and Pb. Except for Pb at site
B, concentrations of the elements analyzed are within the range
typically found in soils.
The background levels of heavy metals in the clay soil from
site B are higher than those in the sandy soil from site A. In view
of the coarse texture and low organic carbon content of the
sandy soil, land cultivation would likely have a greater impact
on the soil and plants grown at site A than site B. The soluble salt
concentration of the treated plot from site A may be injurious to
salt-sensitive plants such as green beans, celery, and most
common fruit crops.
Due to the limited scope of this study, no extensive survey or
chemical analyses of vegetation at the land cultivation sites were
made. Instead, some typical and prevalent species were sampled
and analyzed.
Results from plant analyses indicate differences in plant
uptake due to waste oil treatment, and differences in site
conditions and plant species (Table III). At site A, rag weed and
ice plant grown on the oil-treated plot contained higher
concentrations of Na, Mn, Zn, Se, and Pb than those from the
control plot. These observations related to the trends in soil
data. The plant N contents were reduced by the land cultivation
treatment, probably due to immobilization of available N by the
soil microorganisms. This suggests that nitrogen fertilizers may
be required, if normal plant growth is expected in an area used
for oily waste management.
Table I: Pertinent Information on Study -Sites Used in the Investigation of Vegetative Impacts of Land Cultivation
Location
Site A - Southern California
Site B - Southeastern Texas
Area of Site
14 ha (35 ac)
8.2 ha (20 ac)
Waste Type
Drilling muds
Tank bottoms
API oil/water separator
sludges
Waste Volume
160 to 192 m3/day
(1,000 to 1,200 bbl/dav)
Periodic disposal, 29,600 m^/vt
(185,000 bbl/vr)
Application Rate
2.54 X 103 m3/ha
(6.43 X 103 bbl/ac)
1.27 X 103 m3/ha
(3.22 X 103 bbl/ac)
Fertilization/Liming
None
None
Transportation
From refinery plants to site
From lagoon to landfarm
Soil Characteristics
Sand, well-drained,
slightly acidic
Clay, poorly-drained,
alkaline
Depth of Soil/Waste
Mixture
0.9 to 1.2 m (3 to 4 ft)
15 to 30 cm (6 to 12 in)
Site Age
22 Years
5 Years
Vegetative Types
Weeds and shrubs along the
disposal area perimeter
Same as Site A
Vegetation Sampled
Tall grass, golden bush,
rag weed, and ice plant
Nutgrass leaves and
cockleburr seeds
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194 l.and Cultivation
Table II: Chemical Characteristics of the Surface
Soils from Control and Oil-Treated Plots
Site A
Site B
Constituents^ ^
Control
Treated
Control
Treated
pH
6.04
7.65
7.41
7.40
EC, mnhos/cm
0.40
4.46
2.21
3.91
Oil, %
2.28
2.06
TKN, %
0.006
0.079
0.080
0.134
Org. C, %
0.16
2.53
2.10
5.10
- - -
ppm
- - -
ppm
P
410
230
17.5
17.5
Na
110
230
185
375
B
0.2
2.28
0.2
0.22
Mn
35.4
55.0
65
71.6
Ni
1.5
2.5
4.8
5.3
Zn
7.5
40.7
53.5
71.5
Se
0.022
0.09
0.01
0.028
1.3
1.1
0.6
0.55
Mo
Cd
0.14
0.06
0.06
0.06
Pb
4.2
5.4
212
242
0) Electrical Conductivity (EC) and 8 were n^surecMr. thei saturation extracts;
other elements in ppm were determined in O.IN^HCI extracts.
SUMMARY AND CONCLUSIONS
Nutgrass and cockleburr grown on the oil-treated plot from
site B contained higher concentrations of Zn, Mo, and Pb than
those grown on the control plot (Table III). In contrast, the N
and P contents of cockleburr seed were greatly reduced by the oil
treatment. The levels of Mo and Pb in both plant species from
the oil-treated plot are worthy of notice. The Mo concentrations
approached the undesirable level £10 ppm) for animal con-
sumption. The concentrations of Pb were exceedingly high,
comparable to the Pb concentrations in pasture grasses in a
lead-contaminated area in Northern California (Page, personal
communication). Since the Pb content of the applied oily sludge
was not high (data not shown) and the vegetation from the
control plot also showed high Pb concentration, it is possible
that this is the result of aerial contamination.
The soil and plant data presented should be viewed as
• Tiinary; more detailed investigations are warranted.
Wastewaters and sludges that have been land cultivated are
primiarily from food processing, oil refinery, and paper and
pulp industries. The wastes are composed mainly of organic
material and, thus, are biodegradable. It appears that some
industrial sludges are applicable to land cultivation, if the wastes
are pretreated to remove or recycle the toxic constituents, thus
alleviating the potential hazards of surface and groundwater
and food chain contamination.
Land cultivation of industrial wastewaters and sludges has
received very little attention, probably due to the lack of data on
the economics, productive uses of the site after cessation of
disposal activities, and associated environmental problems.
Preliminary results from a field investigation indicate that land
cultivation of oily sludges has resulted in increased soluble salt
-------
Land Cultivation 195
^ Samples were washed in detergent, rinsed thoroughly, and dried at 70°C.
Concentrated HNO3-HCIO4 was used in sample digestion.
^ Cockleburr seeds were analyzed, since the leaves were dead.
Table III: Analyses of Vegetative Species Sampled from the Control (C)
and Treated (T) Plots of the Two Study Sites1
Site A
Site
B
t*\
Rag Weed
Ice
PI ant
Nutgrass
Cockleburr'"'
Element
C
T
C
T
C
T
C
T
N
2.52
0.37
0'
io
1.29
0.91
1.44
1.42
%
3.05
1.07
P
0.32
0.33
Dpm
0.21
0.21
0.17
0.11
pom
0.29
o.i e
Na
2560
3375
20937
36560
2062
6187
1000
687
B
102
96
12
12
7
15
28
14
Mn
88
95.4
96.7
198
63.6
48.7
18.8
19.1
Ni
6.9
8.5
3.8
2.0
1.9
6.3
3.6
3.1
Zn
101.4
190
40.6
38.2
93.8
131.9
43.8
53.1
Se
0.04
0.125
0.04
0.04
0.23
0.23
0.04
0.0^
Mo
1.2
0.71
0.31
0.1
7.1
9.5
4.2
8.7
Cd
0.05
0.05
0.10
0.21
0.41
0.4,1
0.15
0.1!
Pb
3.12
18.0
3.12
3.28
61.5
90.5
11.2
23.2
and organic carbon contents in soils and accumulation of heavy
metals in soils and plants.
Based on available information and field study results on
management and disposal of industrial wastewaters and
sludges, the following conclusions can be drawn:
1. Land cultivation as a disposal alternative is presently
practiced only by a few industries and on a limited scale in the
U.S. The trend indicates that there will be increased use of land
cultivation in the future.
2. Land cultivation is viable only where soil, climate, waste
characteristics, and environmental conditions permit. The waste
management program can either be related to agriculture or
solely a disposal practice.
3. Few or no comprehensive environmental monitoring
programs are underway at on-going land cultivation sites. A
majority of the states do not now have regulatory statutes
regarding land cultivation; each instance is addressed on a case-
by-case basis.
REFERENCES
1. Adriano, D. C., Novak, L. T., Erickson, A. E., Wolcott, A.
R., and Ellis, B. G. "Effect of Long-Term Land Disposal by
Spray Irrigation of Food Processing Wastes on Some
Chemical Properties of the Soil and Subsurface Water."
Journal of Environmental Quality. 4:242-248. 1975.
2. Chaney, R. L. "Crop and Food Chain Effects of Toxic
Elements in Sludges and Effluents." Proceedings of the
Joint Conference on Recycling Municipal Sludges and
Effluents on Land. Champaign, Illinois, pp. 129-141. July
1973.
3. DeRoo, H. C. "Agricultural and Horticultural Utilization
of Fermentation Residues." Connecticut Agricultural
Experiment Station. Bulletin No. 750. 1975.
4. Epstein, E. and Chaney, R. L. "Land Disposal of Industrial
Waste." Proceedings of the National Conference on Man-
agement and Disposal of Residues from the Treatment of
Industrial Wastewaters, Washington, D.C. pp. 241-246.
February 1975.
5. Hunt, P. G., Glide, L. C., and Francingues, N. R. "Land
Treatment and Disposal of Food Processing Wastes."
Conference on Land Application of Waste Materials, Soil
Conservation Society of America, Ankeing, Iowa. pp.
112-135. 1975.
6. Kincannon, C. B. "Oily Waste Disposal by Soil Cultivation
Process," EPA-R2-72-100. U.S. Environmental Protec-
tion Agency. December 1972.
7. Lazar, E. C. "Summary of Damage Incidents from
Improper Land Disposal." Proceedings of the National
Conference on Management and Disposal of Residues
from the Treatment of Industrial Wastewaters, Washing-
ton, D.C. pp. 253-257. February 1975.
-------
196 Land Cultivation
8. Lehman, M. P. "Industrial Waste Disposal Overview."
Proceedings of the National Conference on Management
and Disposal of Residue from the Treatment of Industrial
Wastewaters, Washington, D.C. pp. 7-12. February 1975.
9. Letey, J. and Farmer, W. J. "Movement of Pesticides in
Soils" Pesticides in Soil and Water, W. D. Guenzi(ed.). Soil
Science Society of America, Inc., Madison, Wisconsin, pp.
67-97. 1974.
10. Lewis, R. S. "Sludge Farming of Refinery Wastes as
Practiced at Exxon's Bayway Refinery and Chemical
Plant." Presented at the National Conference on Disposal
of Residues on Land, St. Louis, Missouri. September
13-15, 1976 (in press).
11. Nash, R. G. "Plant Uptake of Insecticides, Fungicides, and
Fumigants from Soils." Pesticides in Soil and Water. W. D.
Guenzi (ed.). Soil Science Society of America, Inc. Madi-
son, Wisconsin, pp. 257-299. 1974.
12. National Academy of Sciences-National Academy of
Engineering. "Water Quality Criteria, 1972." U.S. Govern-
ment Printing Office. Washington, D.C. 1974.
13. Noodharmcho, A. and Flocker, W. J. "Marginal Land as
an Acceptor for Cannery Waste." J. Amer. Soc. Hort. Sci.
700:682-685. 1975.
14. Page, A. L. "Fate and Effects of Trace Elements in Sewage
Sludge When Applied to Agricultural Lands."
EPA-670/ 2-74-005. U.S. Environmental Protection
Agency. January 1974.
15. Phillips, C. R. and Nathwani.J.-soil-Waste Interaction- a
State-of-the-Art Review." Solid Waste Management
f976°rt 76 ^nv'ronment Canada. October
16. Phung, I., Ross, D., and Landreth, R. "Land Cultivation
of Municipal Solid Waste." Presented at the Third Annua/
Research Symposium: Management of Gas and Leachatl
in landfills, St. Louis, Missouri. March 14-16, 1977 /¦;*»
press). '
17. Poison, R. L. "Relractory Metals Processing Waste Utiliza
tion on Dayton SiKy Clay Loam," M.S. Thesis Ore»r»n
State University, Corvalhs. 1976.
18. Pound, C. E. and Crites, R. W. "Wastewater Treatment and
Reuse by Land App j jcal-,on" Volume U
EPA 600/2 73 006b U.S. Environmental Protection
Agency. August 13, 1973.
19. Powers, P. W. "How to DiSpose 0f Toxic Substances and
Industrial Wastes. Noyes Data Corporation, Park Ridse
New Jersey. ® •
20. Wallace, A. T. "Land Disposal of Liquid Industrial
Wastes." R. L. Sanks and Asano (eds.). Land Treatment
and Disposalof Municipal and Industrial Wastewater Ann
Arbor Science Publishers, Inc.( Ann Arbor, Michigan n«
147 162.1976. e»»-pp.
-------
A Non-Hazardous, Simple
and Economical Method
for the Disposal
of Metal Sludges,
Using a Segregated Landfill L. E. Lancy
Lancy, Division of Dart Environment
and Services Company
Zelienople, Pennsylvania
INTRODUCTION
The waste treatment efforts in the metal finishing industry are
mainly chemcal-physical treatment processes. The chemical
content of these wastes is nearly completely inorganic in nature.
The waste is generated in chemical or electrochemical process-
ing of the metal surfaces, electrodeposition, chemical or electro-
lytic etching, etc. Therefore, it is high in dissolved or particulate
metal salts. The chemical precipitation and removal of the solids
from the liquid waste is one of the most important objectives.
Treatment effect may also be directed towards the chemical
precipitation of such anions as, for example, the sulfates,
phosphates, fluorides, etc. All these solids removed from the
liquid waste are included in the sludges generated in metal
finishing waste treatment and are usually called by the generic
term "metal sludges."
It is important to distinguish the sludges generated in waste
treatment from other metal finishing solid process waste that
has not passed through the waste treatment system. As an ex-
ample, filter cake solids, sludges, or crystals removed from the
bottom of processing tanks, spilled or caked salts swept off from
the processing area, salts removed from a normally molten salt
bath, etc., may all have high residual solubility and can be con-
sidered suitable for sludge disposal only after they have been
redissolved and passed through the respective unit processes
normally available in the treatment plant.
Recognizing the harm that can be caused by untreated metal
finishing waste, industrial and regulatory effort has been
directed for many years toward generating suitable treatment
technology with a reasonably predictable effluent quality.
Interstate, national, and even international guidelines have
followed stipulating a desired effluent quality for each dis-
charge. The sludges generated by these treatment plants have
been disposed mostly on land, but no uniform practices have
been developed. Some of the State Regulatory Agencies
recognized the need for developing recommendations for safe
disposal practices, but the general scarcity of reports on the
various practices and investigation regarding long-range envi-
ronmental effect, did not allow the development of uniform
practices. The many years of experience, since it was not
available for scrutiny, did not allow a concensus regulation of
safe land disposal practices and we find in some areas the metal
sludges lumped in with all other hazardous waste without clear
directives for their disposal.
Precipitation and Residual Solubility
Chemical waste treatment aims to precipitate the metals so
that the soluble residuals are reduced to the lowest possible lev-
els. The precipitates are usually the hydroxides, carbonates,
phosphate, or the oxides in various hydrated states. One of the
problems encountered is that the wastes usually contain a
mixture of the heavy metals, some of which may require a
reasonably high pH for nearly complete precipitation, while
some amphoteric metal compound may concurrently show an
increased solubility. The residual soluble metal content, when
attempting nearly complete precipitation, will depend on the
pH, background salt concentration, concentration of the
various metals in the solution, nature of the alkali employed,
potential presence of organic complexing agents, etc. The
technical literature extensively discusses the various problems
that may be encountered.1'3 To reach the theoretical solubility
equilibrium requires far more time than available; we may state
that, as a rule, the residual solubility greatly exceeds the theo-
retical equilibrium.
Recognizing the significantly higher levels of these soluble
residuals, it was assumed that resolubilization of the precipi-
tated metals will yield the same high levels of metal content in
rain or natural waters. Contrary to this assumption, our
investigation shows that the solubility product is far below
concentration in the supernatant and follows the theoretical
solubility equilibria. Low soluble heavy metal content of natural
waters, drinking water reservoirs, artificial impoundments
behind dams, shows the same trend, though the sediment analy-
sis indicates significant accumulation of metal particulates.4'7
Leach tests on dredged solids, when investigating the potential
environmental hazard due to the significant heavy metal
content, has also proven the minimal residual solubility that can
be assured.8 In the absence of organic complexing agents, the
low soluble residuals of heavy metals are established slowly as is
shown by Silva for copper and assuredly similar equilibria are
applicable to all the heavy metals which could be of concern
from metal finishing origin.9 Equilibrium in resolubilization is
established much faster; no additional gain occurs after one
hour when using deionized water.
Disposal of Metal Sludges
on Sanitary Landfill or
Combined with Solid Waste
from Sanitary Treatment Plants
It must be assumed that the "hazardous solid waste" categori-
zation of metal sludges has been caused by the increasing
number of treatment facilities constructed during the last few
years, with minimal planning regarding the ultimate disposal of
the solid waste generated. Experience accumulated during the
previous decades was not available; minimal effort was invested
in studying existing sludge disposal sites and reports on their
performance. It is also noteworthy that the previous years' waste
197
-------
198 Segregated Landfill
treatment effort was mainly by industry discharging their
effluent directly into natural bodies of water and therefore
subject to regulatory control for many years. Industrial sites,
such as these, usually provided sufficient land area so that the
sludges could be accumulated in a segregated manner, either in
lagoons or sludge drying beds and buried on the property of the
industry. We have reported elsewhere on the performance and
the absence of soil or groundwater contamination experienced
with this practice.111' 11 However, lacking regulatory attention,
the safety of such disposal is not insured. Indiscriminate
dumping of untreated wastes, using the metal sludge disposal
sites also for dumping oil, solvents, various trash, negates the
original design intentions and regulatory attention is needed
even for those disposal sites serving one industrial plant only
and located on the owner's property.
Disposal on a community or sanitary landfill, mixed with
organic solids, creates an entirely different set of environmental
conditions.12." While there is no concern for anaerobic
decomposition in a segregated metal sludge landfill, such
conditions are always anticipated with disposal sites of prepond-
erantly organic origin. Organic acids in general have even great-
er solubilizing capabilities for heavy metals than the strong
mineral acids. This can be easily demonstrated by subjecting the
insoluble metal compounds to an organic vs. mineral acid leach
test at the anticipated pH conditions.14 The reprecipitation of
the metals from organic complexes is also greatly reduced if
percolation through alkaline soil layers is assumed to help to
reduce the pollutional hazard.
Incineration with Oily
Waste or Combined with
Organic-Type Solid Waste,
such as Refuse or
Sanitary Solids
Most of the low-boiling-point metal content of the sludges is
volatilized. With condensation of the vapor emission, particu-
lates are formed which are extremely small. Small particulates
of lead, cadmium, and zinc constitute a serious atmospheric
health hazard and, in addition, these metal contaminants are
broadly distributed on the land, potentially contaminating agri-
cultural crops. 15'IS It has been shown that the presently available
atmospheric emission control devices are not sufficiently
effective.19 Additionally, some of the metals in the sludges, such
as chromium and molybdenum, are oxidized during incinera-
tion, creating soluble, toxic metal residues in the remaining
ash.20'21
Obviously, incineration is not an environmentally desirable
disposal approach and therefore limited research effort has been
expended on the atmospheric and water pollution problems that
could be anticipated. Most of the reported experience and
investigative data refers to coal burning plants. It may be safely
assumed, however, that the metal compounds subjected to the
same temperature and oxidizing conditions will generate the
same type of reaction products.
Segregated Landfill Experience
and Recommendations
Sludge Lagoons
The sludge-lagoon-type disposal systems have been the
common disposal technique for many years. No environmental
harm has occurred from any of these, as explained earlier, but
the method had certain serious shortcomings and doesn't lend
itself for general applications where many industries could
cooperate, or a municipality could set up a common disposal site
for the various industries.10,11 The original aim has been to fill
the lagoon with sludges and monitor the discharge of the
effluent diluted by rainwater. Close control would be necessary
to supervise multi-industrial dischargers; the drying of the
disposed sludges is slow; the emptying of the lagoons or final
filling and compacting with suitable fill material, allowing the
return of the lagoon area to other uses, is expensive.
Sludge Drying Beds and [Mndfill
1. In Grand Rapids, Michigan, the Municipal Water Quality
Authority maintains a community land disposal and segregated
metal sludge landfill. A licensed hauler takes the wet sludge to
the disposal area upon certification that the treatment meets the
criteria of efficient treatment. The liquid sludge is pumped into
shallow pits (2-3' deep) where they dry sufficiently well in 30-60
days to be scopped out with a front loader and delivered to the
nearby landfill, which also is restricted to be used for metallic
sludge waste only. Several of the described shallow pits are
prepared to allow rotational use.
The operator of the site is responsible to install and maintain
monitoring wells, sampling and testing services, reporting to the
State Agencies regarding performance. Extensive ground water
tests preceded the establishment of the landfill site, and since the
beginning of the operation, no change in the ground water has
been detected (8 years).10'11
2. Lancy Laboratories is cooperating with the State of
Kentucky-EPADNR to prove the safety and efficiency of a
simple and economical landfill disposal scheme for metal
finishing sludges. The test program is now in its fifth year.l0,n
The landfill is located in Maysville, Kentucky, on private
land, property of the industrial concern generating the waste
(Wald Mlg. Co.). The sludge supernatant is routinely analyzed
for soluble metals, cyanide, and hexavalent chromium to insure
that the treatment is proper. The sludge at the time of hauling
contains 10-15% dry solids and is thickened and dewatered by
gravity. The sludge bed is at ground level, prepared with a 4"
deep limestone gravel surface layer, and is surrounded by a 3'-4'
high mound of dirt which is excavated from the sludge bed
surround area, thereby creating a 2' deep canalization
surrounding the beds. Figures 1 and 2 are schematic and photo-
graphic views of the layout. Storm water and seepage from the
sludge beds is led to a low area following the land contours
where the drainage goes through a 200-250 gal. sampling pit
before discharge. Four times a year, after rainy days, a sample is
collected, analyzed, and the results reported to the State.
Table I: Control Test Results from Land Disposal
Supernatant
Wet Sludqe
(mq/1)
Leachate
from Drying
Bed (mq/1)
Dl Water Leach
Test from Sludge
Sample (mg/li
pH
7.75
8.0
7.75
CN3
< 0.01
< 0.01
0.02
cnt
< 0.01
< 0.01
0.02
cr6 +
< 0.01
< 0.01
< 0.01
cr3+
0.03
< 0.01
0.03
Zn
0. 14
0.02
0.02
Ni
0. 27
0.10
o.l
Table I shows a typical analysis for this type of treated sludge
leachwater seepage, and the typical metal content of the
supernatant water from which the sludge is separated in
thickening and drying. Included also is an analysis from a leach
test where 1 g of a washed and dried sludge sample is stirred for
one hour in 1 litre of DI water to establish the soluble residuals
content.
It is contemplated that this type of solid waste disposal will
allow the covering of an 18"-24" layer of dried sludge with a new
layer of limestone, compacting the soil and building up the land
contours as the years pass. Alternatively, the dried sludge can be
-------
Segregated Landfill 199
^SAMPUNS Pir
^•STOOM DftAltf
Figure 2: Sludge Bed and Landfill in Maysville, Ky.
-------
200 Segregated Landfill
pushed to provide a 4'-5' high metal sludge layer that can be
covered with soil. We contemplate that the landfilling of filtered,
dry sludge would occur in a similar manner. The berm surround-
ing the landfill would protect the metal sludges from being
washed down by storm waters.
Laboratory Investigation and
Confirmation of
Experimental Results
When discussing chemical precipitation of the heavy metals
from waste solutions, we have explained that the concentration
of the soluble residuals is always considerably higher than the
solubility equilibrium of the precipitate. Before conducting the
leach test, the sludges therefore are washed to remove the
mother solution trapped in the interstices of the solids or present
as supernatant over the sludges after settling. We feel justified in
disregarding the environmental significance and pollution
potential of the somewhat higher metal content of the supernat-
ant because the total volume of the entrapped liquid is relatively
small, Our main concern has been only the long-range leacha-
bility of the solid waste by the percolation of rain water. Our
usual leach test consisted of stirring 1 g of wet sludge in 1 liter of
deionized water. We have considered this to be the most severe
test because natural percolation would create far less severe
solids-liquid contact conditions and aerated deionized water is
known to be a most aggressive solvent. Possibly these tests
shouldn't even be called "leaching tests" because the severity of
the stirring, surface area exposed to the liquid, etc., doesn't have
any resemblance to the anticipated conditions in the field.
Basically it is a test to approximate solubility equilibrium of the
metal compounds in the sludge.
Concern has been raised by the relevant research staff of EPA
desiring a higher ratio of solids to leach water and longer leach
times to reach equilibria. Similar considerations were also raised
if absorbed carbon dioxide and therefore lower pH would not
affect the test results.
Our experience with processes aiming to recover metal values
using a mineral acid leach system has indicated that aged sludge,
which has been allowed to dry in air, appears to become far less
easily soluble.22 We have therefore thought it would be desirable
to compare leachability after air drying also.
We have also considered that testing sludges received from a
plant using a waste treatment method with which we have not
been familiar may also affect the results. To aid our mutual
interest, the EPA-MER Laboratories provided us with a metal
sludge sample from a source unknown to us for our
investigations to help clarify some of these questions.
Test Conditions Applied
Using Metal Sludge
from EPA-MERL
A 400 g sample of the wet sludge was washed with 1.5 liter
deionized water on a Buchner vacuum filter:
A = metal concentrations found in the collected wash waters.
Table II: Leach Test Results, Soluble Metals in mg/l
All other tests used this washed sludge; the reported weights are
of wet sludge.
B = 100 g sludge stirred lor one hour in 250 ml deionized water
(pH 6.4), then allowed to stand for one week. The filtered sample
(0.45 ^filter) analyzed for the dissolved metals.
C = 100 g sludge air dried for one week, stirred in 250 ml
deionized water (pH 6.4) for one hour and a filtered sample
taken.
D = 100 g sludge stirred for one hour in deionized water, the
pH of which has been adjusted to 5.4 with absorbed C02. After
the one hour stirring, the solution was left to stand for one week
before the filtered sample was taken.
E = 100 g sludge that was air dried for one week has been
stirred for one hour in 250 ml carbonated deionized water (pH
5.4) and a filtered sample tested.
Discussion
a. The test confirms the fact that the first volumes of wash water
contain higher soluble metal residuals than those found in
subsequent leach tests. The soluble metal content of the
sludge is generally a good indicator of the degree of
treatment and can be used as an acceptance test for the
suitability of land disposal. (Grant Rapids acceptance test
<0.5 mg/l Cu, Ni, Zn"1'").
b. There doesn't seem to be any gain in leaching during the one-
week additional soaking after the one-hour stirring.
c. The one-week air drying and aging of the sludge shows
significant reduced leachability only for Cu, Ni, and Zn.
d. The rain water pH reduction due to carbon dioxide absorp-
tion or acidic atmospheric pollutant doesn't create increased
metal solubility in leaching. The buffering capacity of the
rain water (or deionized water) is very low and the pH change
can be great, but the buffering salt content of the sludge is
very high. During waste treatment, significant quantities of
calcium carbonate are included into the solids, also the
landfill area is underlain with limestone to provide a porous
leachate base, additional buffering capacity and a firmer
base for subsequent use of earth moving equipment.
e. The origin of the sludge sample may show significant
variations in leach test results, but the leachability is
sufficiently low and the segregated landfill area relatively
small so that the environmental hazard remains insignifi-
cant.
f. We have omitted a detailed discussion of the minor volume
of metal finishing sludges that require additional sealing
because the soluble leachate could cause underground
contamination. In this category belong the sludges from
sulfide precipitation, calcium fluoride, barium chromate,
and metal wastes treated with organic adsorbents such as
peat, starches, etc. As discussed elsewhere10'11 sludges of this
type have to be segregated and sealed before landfilling or
sealed in a separate landfill.
CONCLUSIONS
The concern regarding recycle of heavy metals from metal
sludges is due to our experience with environmentally unsuita-
ble practices. Disposal of these sludges in sanitary landfill,
accumulation in sanitary solids, incineration, all create measu-
rable and sometimes serious hazards by contaminations of the
land, aquifers, and atmospheric fallout. Disposal of these
sludges using a segregated landfill method is simple, econom-
ical and safe. It also allows the potential recovery of accumu-
lated metal values at some future time when this may become
economically feasible.
A program such as this cannot be put into practice without
regulatory involvement. At some point we have to stop deliber-
ate disposal of these sludges into sanitary sewer systems, depos-
A
B
C
D
E
pH
7.80
7.80
7.50
6.75
6.60
Cu
0.32
0.17
0.15
0.09
0.09
Ni
0.34
0.21
0.17
0.14
0.12
Cr
0.07
0.01
0.04
0.03
0.07
Zn
0.36
0.27
0.14
0.18
0.14
Cd
0.10
0.07
0.05
0.06
0.04
-------
Segregated Landfill 201
ition into sanitary landfill, and incineration with organic wastes,
oils, etc. The segregated landfill has to be under regulatory
control; the sludges delivered to the landfill site should carry a
certification regarding adequate treatment and should not be
contaminated with organic wastes. Only licensed haulers should
be allowed to deliver sludges to these sites and the landfill itself
should be monitored by periodic testing of the leachate.
REFERENCES
1. Lancy, L. E., "pH-Wert und Loslichkeit von Schwermetall
Hydroxyden," Galvanotechnik 54, 3, 139 (1963).
2. Hartinger, L.., "Die Chemie der Metallausfallung Aus
Abwassern," lnterfinish 68, Hanover, May, 1968, p. 279.
3. Hartinger, L., "Abwasserreinigung in der Metallverarbei-
tenden Industrie Ausfallung der Schwermetalle," Bander
Bleche Rohre, 1 October, 1963, p. 535; II December, p. 638;
III January, 1964, p. 14; IV September, 1965, p. 524.
4. Lee, G., "Role of Hydrous Metal Oxides in the Transport of
Heavy Metals in the Environment," Progress in Water
Technology, 17, p. 137-147 (1975).
5. Mathis, B. J., and Cummings, T. F., "Selected Metals in
Sediments, Water, and Biota in the Illinois River," Journal
WPCF45, 7, 1573 (1973).
6. Pita, F. W., and Hyne, N. J., "The Depositional Environ-
ment of Zinc, Lead, and Cadmium in Reservoir Sedi-
ments," Water Research 9, 8, pp. 701-706 (1975).
7. Bard, C. C., et al., "Silver in Photoprocessing Effluents,"
Journal WPCF 48, 2, pp. 389-394 (1976).
8. Lee, G., et al., "Leaching and Bioassay Studies on the
Significance of Heavy Metals in Dredged Sediments.
Presented at the International Conference on Heavy Metals
in the Environment, Toronto, Canada, Oct., 1975 (Pro-
ceedings in print).
9. Sylva, R. N., "The Environmental Chemistry of Copper in
Aquatic Systems," Water Research 10, pp. 789-792 (1976).
10. Lancy, Div. of Dart Environment and Services Company,
"Survey and Study for theNCWQ, Regarding the Technol-
ogy to Meet Requirements of the Federal Water Pollution
Act for the Metal Finishing Industry," U.S. Department of
Commerce, NTIS (No. PB 248-808), Springfield, Va.,
22151.
11. Lancy, L. E., "The Fate of Heavy Metals from Metal
Finishing, Land Disposal of Solid Waste." Presented at the
Engineering Foundation Conference on Land Application
of Residual Materials, Easton, Maryland, Sept., 1976.
(Proceedings in print).
12. Curry, N. A., "Hazardous Waste Management and Dispo-
sal." Presented at the Engineering Foundation Conference
on Land Application of Residual Materials, Easton,
Maryland, Sept., 1976. (Proceedings in print).
13. Chian, E. S. K. and DeWalle, F. B., "Sanitary Landfill
Leachate and their Treatment," ASCE Journal Env. Eng.
102 (EE2), pp. 411-431 (1976).
14. Malo, B. A., "Partial Extraction of Metals from Aquatic
Sediments," Environmental Sci. & Techn. 11, pp. 277-282
(1977).
15. Natusch, D. F. S. & Wallace, J. R., "Urban Aerosol
Toxicity: The Influence of Particle Size," Science, 186, 695
(1974).
16. Klein, D. G. and Russell, P., "Heavy Metals: Fallout
Around a Power Plant," Envir. Sci. & Techn. 7,357 (1973).
17. Klein, D. H., "Pathways of Thirty-seven Trace Elements
through Coal Fired Power Plant, "Envir. Sci. & Techn. 9,
973 (1975).
18. Campbell, W. J., "Metals in the Wastes we Burn?" Envir.
Sci. & Techn. 10,5 (1976).
19. Ondov, J. M.,etal., "Comparison of Particulate Emissions
from a Wet Scrubber and Electrostatic Precipitator at a
Coal Fired Power Plant," ACS Div. E. C. 173rd Nat'l
meeting, New Orleans, La., 1977).
20. Nietz, S. R., "Untersuchungen uber die Bildung von
Chromat Beim Vergluhen Chromhaltiger Abw'assersch-
lamme," Galvanotechnik 64, 11, 998 (1973).
21. Brown, J., et al., "The Disposal of Pulverized Fuel Ash in
Water Supply Catchment Areas," Water Research 10, pp.
1115-1121 (1976).
22. U.S. Patent No. 3,953,306.
-------
R esour ce-C onserv ation
Pollution-Control Technology:
An Idea Whose
Time Has Come Joseph T. Ling
3 M Company
St. Paul, Minnesota
A balancing act is what we're called on to perform in coping
with increasingly complicated and demanding waste treatment
and disposal problems. On one hand, we're facing compliance
deadlines in the Clean Air and Clean Water acts. On the other
hand, we're asked to conserve energy and resources while
contributing toward more jobs in an expanded economy.
This is a difficult task, although not an impossible one, if we
are creative as well as technically aggressive in our search for
realistic and effective answers to environmental problems.
My native Chinese language is one of word pictures which
sometimes convey more meaning than their English transla-
tions. Consider the word "crisis," which is much overused in
relation to environmental matters.
In Chinese, the word "crisis" is composed of two separate
characters. They are "danger" and "opportunity." For our
purposes today, perhaps we can call them "problem" and "op-
portunity."
I can't add much to your knowledge and understanding of
waste treatment and disposal problems, particularly not after
the excellent technical presentations which are being given here.
But 1 do have something to say about the opportunity which
may be present in what I call a resource-conservation-oriented
approach to pollution-control problems.
Confucious once said that speaking to an audience of highly
intelligent people is like eating soup with chopsticks. It's easier
to stir things up than to satisfy the appetite.
Today, 1 would like to accomplish both things ... to stir
your interest in this resource-conservation approach to pollu-
tion control . . . and satisfy your appetite for information on
what this is all about.
First ... to stir.
Unfortunately, but understandably, industry has been preoc-
cupied with pollution-removal technology in solving our envi-
ronmental problems. This generally is accomplished by provid-
ing a "black box" at great expense, which is attached to the end
of a production line, fn fact, most existing legislation requires
such a "black-box" installation.
This type of "black-box" approach has been the conventional
wisdom of pollution abatement. But, there's an idea whose time
has come. This is resource-conservation-oriented, pollution-
control technology . . . a vital supplement to pollution removal
technology.
Resource-conservation is a simple concept, but it has pro-
found implications. The concept is no more or less than the
practical application of knowledge, methods and means to
provide the most rational use of resources to improve the envi-
ronment.
Resource-conservation technology means eliminating the
causes of pollution before spending money and resources to
clean up afterward. It also means learning to create valuable re-
sources from pollution . . . like the making of nylon and other
materials from the waste byproducts of petroleum some years
ago.
It's in the overall interest ol our society to adopt this re-
source-conservation-oriented approach to pollution control.
But this must ... by necessity ... be done in context with
three environmental realities:
Environmental issues are emotional.
Environmental decisions are political.
Environmgntal solutions are technical.
No technical solution to a pollution problem can be accepted
if it is not presented in harmony with the emotional and political
realities.
So. let's begin by looking at the "black-box" approach. In the
words of our venerable Chinese philosopher, this is "costly as
hell."
Natural resources, energy, manpower and money are con-
sumed to build a "black box," and more resources are consumed
to operate the "black box" throughout its life span. At its very
best, the "black box" only temporarily contains the problem, it
does not eliminate the problem.
Because residue from the "black box" does comprise a
disposal problem of its own. And, the growing number of new
requirements . . . such as the Resource Conservation and
Recovery Act . . . make residue disposal a very complicated
and expensive endeavor.
By our using the "black box," we also are responsible for
creating what 1 call off-site pollution . . . waste generated by
those who supply the materials and energy consumed in the
pollution-removal process itself. This pollution could be gener-
ated at facilities many miles from the "black box."
In addition, resources consumed and residue produced for
pollution control rise exponentially as removal percentages
increase to the last few points.
When all these factors are considered, it's apparent that the
"black-box" approach ... at some point . . . creates more
pollution than it removes, and consumes valuable resources out
of proportion to the benefit derived.
So, we have created an environmental "Catch22." It takes re-
sources to remove pollution. Pollution removal generates
residue. And it takes more resources to dispose of this residue.
And, disposal of residue also produces pollution.
U nfortunately, many of the resources we need are limited, and
many of them are not renewable. It is courting disaster for us not
to make the best, and least, use of these resources in dealing with
increasingly complicated environmental pollution problems.
This is why we in industry no longer can be content with
merely relying on conventional pollution-removal technology
-------
Resource-Conservation Control 203
the "black-box" techniques.
We all recogni/.e that pollution is a form of waste. And "waste
not, want not" is a motto as true now as it was for all of those
generations before us.
In my opinion, the very sustainability of a continuous,
dignified life on this earth depends ... in the long run ... on
reestablishing a conservation-oriented society ... a conserva-
tion-oriented economy . . . and, above all, a conservation-
oriented value system.
This value system ... by necessity . . . must be based on a
total concept ol resource-conscrvation-oricnted technology
which involves raw-material supply, production, consumption
and disposal.
In short, the concept is to use a minimum of resources and
create a minimum of pollution. These worthy goals are unlikely
to be met only with the "black-box" approach. As regulations
pinch tighter, the "black box" gets bigger, more complex and
costly.
Until recently, most of industry's abatement efforts and at-
tention were directed toward what I call "first-generation"
pollution problems. They are the kind of problem created in the
manufacturing process in the factories and regulated by the
Clean Air Act and Water Pollution Control Act, among others.
Lately, public attention and legislation has been focused on
what I call "second-generation" pollution, which relates to prod-
uct-use problems.
Product-related pollution is regulated by legislation such as
the Toxic Substances Control Act and the Resource Conserva-
tion and Recovery Act. These and other laws are concerned with
the environmental impact of products after they leave the
factory.
The conventional "black-box" approach deals only with
"first-generation" problems. It does not and cannot cope with
"second-generation" problems . . . and the reason is simple. If a
pollutant exists in a product, then a problem is created for the
user. And the user's problem is beyond solving by the "black
box" in the manufacturer's factory.
The two types of pollution are interrelated, because the "sec-
ond-generation" pollution problem which exists in a product
could become a "first-generation" problem for user.
For instance, if the user is another manufacturer, he will have
to build a "black box" to cope with this problem ... or find a
substitute product. In this case, the first manufacturer may have
lost the market.
If the user is a direct consumer, then he or she does not have a
"black box" to control pollution. The problem could become a
public issue . . . such as detergents, automotive emissions,
PCB's or mercury contamination.
3M has been very concerned about the product-related
pollution problem. Our scientists recently eliminated a mercury
catalyst from an electrical insulating resin. This did away with
any pollution problem created for the user by the mercury. The
new formula was more environmentally acceptable and pre-
vented a substantial loss in sales.
In our Company, this approach is likely to become stan-
dard . . . required not only by government regulation but by the
economic forces of competition and resource shortages.
It appears to me that resource-conservation pollution-control
technology is the third and previously missing leg in the envi-
ronmental triangle. Without it, there appears to be no incentive
for advanced technical solution to relate to the emotional issues
which prompt political decisions.
3M's initial interest in an organized approach to resource-
conservation pollution-control technology was generated dur-
ing the economic downtturn of 1974. Like other companies, 3M
was caught in a price-cost squeeze and looked for fat to trim.
Our board chairman . . . Ray Herzog . . . asked what our
Environmental Engineering and Pollution Control organiza-
tion could contribute to lower costs. We told him.
"Nothing . . . not if it means failure to comply with regu-
lations."
We explained, however, that we could save some money by
promoting development of a concept of "no pollution, nocost."
With Herzog's full support, reflected throughout top manage-
ment, we encouraged resource-conservation technology by
organizing a Company-wide program to promote innovation
that reduces or eliminates pollution at the source. We call this
the Pollution Prevention Pays Program, or 3P Program.
The 31' Program was begun in April 1975 to focus on product
reformulation, process modification, equipment redesign and
recovery of waste materials for reuse.
The name Pollution Prevention Pays was selected, because we
had defined four distinct payoffs from the program . . . better
environment, conserved resources, improved technologies and
reduced costs.
The program is conducted by and for our operating divisions.
It is run by a 3P Coordinating Committee which represents 3M's
engineering, manufacturing and laboratory organizations and
the corporate Environmental Engineering and Pollution Con-
trol organization.
In the U.S. alone, the committee . . . so far. . . hasjudged45
projects. Nineteen of these were selected for awards. Eighteen
were under study. And eight have been rejected.
The 19 award-winning projects have eliminated the equiva-
lent of 73-thousand tons of air pollutants annually . . . 500-
million gallons of polluted wastewater and 28-hundred tons of
sludge annually.
In addition, these projects have produced a total estimated
savings to 3M of about $11 million. These savings are mostly
from eliminated, reduced or delayed installation of pollution-
control equipment and operating costs. Also included are
savings from improved products and processes and some sales
retained from products purged of a pollutant or toxic compo-
nent.
I'd like to emphasize that these results of our 3P Program are
not considered the "fruits of our labor." They are seen
as seedlings from which a much larger crop of ideas will be
harvested continuously.
We're advancing the concept within the limits of our own
human, mechanical and financial resources. The program is
being taken from division to division and plant to plant in the
United States. It also has been presented to 14 3M subsidiaries
overseas . . . eight of which have formed their own programs.
The 3P awards primarily offer personal recognition.
This recognition consists of an engraved and handsomely
framed certificate signed by the chairman of the board . . . my-
self . . . and the vice president of the division for whom the
recipient works.
This certificate is presented by the vice president at a meeting
of the division management or other suitable occasion.
The division itself may provide other incentives, and . . .
above all. . . it does the recipient no career harm to become
known as a creative solver of technical problems.
One of our more interesting projects involved reformulating a
new-product process. A group of scientists and engineers found
that the product would have an odor problem from a toxic
component. The original process also produced 12 pounds of
pollution per pound of product. Using the 3P concept, the
laboratory developed a new process that eliminated the toxic
substance that smelled bad. The lab people also reduced other
pollutants to only two pounds of waste per pound of product.
And ... in addition . . . their new process reduced manufac-
turing costs considerably.
I'm proud of what our people have done, but I also want to
emphasize that resource-conservation idea is neither new nor
unique. Our interest in resource conservation . . . and our
-------
204 Resource-Conservation Control
results . . . are no more than an example of what is being done
in a well-organized manner.
Resource-conservation technology also works better for some
companies than for others. In most cases, our manufacturing
processes are revolutionary, not evolutionary. 3M is fortunate
to be a new-products-oriented company. We have a large
research program, and we have many opportunities to eliminate
pollution from new and modified products and processes.
In some industries, however, processes cannot be changed
easily or perhaps at all without disrupting or halting total pro-
duction. The changeover may not be cost effective ... or there
may be no conservation technology to eliminate some pollution
sources. Many heavy industries are examples of where re-
source-conservation technology may not apply.
However, the goal of industry should be to use resource-
conservation technology where and when possible and practical,
in its own interest. Industry must apply its own ingenuity to de-
velop its own know how relating to its own resource-
conservation approach to its own pollution problems, just like
each industry developed its own technology to produce its own
products.
We feel the concept definitely ... for the long run ... is
more environmentally and cost effective than the conventional
"black-box" approach. And it provides an atmosphere in which
environmental technical solutions can be related to the emo-
tional issue and the political decision. Industry has the technical
know-how and is taking the lead. This is important right now,
while all of us are concerned about revisions being proposed to
the Clean Air and Water Pollution Control Acts.
We should not overlook the fact that some governmental reg-
ulations actually discourage the use of this concept. A good ex-
ample is regulating water discharge by relating only to
concentration of pollutants and not the total amount. This dis-
courages the use of recycling to improve the production process,
because recycling may raise the concentration, even though it
drastically lowers the total amount of pollutant discharged.
In a broad sense, we believe the resource-conservation
approach to our environmental pollution offers a new dimen-
sion in our effort to improve our environment . . . and this
concept should be considered by those who amend environ-
mental law.
As I've indicated, however, the advantage of this concept
cannot be realized fully until the government acts positively. If it
is our mission in industry to develop new solutions to pollution
problems, then government is obligated to act positively to
make these new approaches attractive to those who can use
them.
In this matter, timing is important. Advocating a different
approach in a tightly regulated field such as pollution abatement
is like going surfing.
To succeed in pollution abatement or surfing, you've got to
rid the crest of a good wave. Too early, and you can't get going.
Too late, and you're swamped. In pollution control
today . . . "the surf is up" for resource conservation. It, indeed,
is an idea whose time has come.
-------
Wastewater Treatment
Utilizing Water Hyacinths
(Eichhornia Crassipes)
(Mart) Solms
B. C. Wolverton
and
Rebecca C. McDonald
National Aeronautics and
Space Administration
NSTL Station, Mississippi
INTRODUCTION
In the last two decades, the practice of dumping either
untreated or partially treated waste into rivers and streams has
become a major source of conflict between industry and groups
of citizens concerned about protecting our environment. Conse-
quently, the U.S. Environmental Protection Agency was char-
tered to impose and enforce regulations on the quality of the
wastewater that industries can discharge into receiving water.
This agency is slowly imposing stricter standards on industrial
wastewater effluents with the aim of eventually achieving "zero
discharge" of any industrial pollutants into receiving waters
(Public Law 42-500).
Whether or not zero discharge is a realistic goal is a matter of
debate. In any case, the discharge of industrial waste must be
regulated, since its constituent components, both organic and
inorganic, have been shown to have deleterious effects. Some
organic compounds may act directly as toxins or carcinogens.
Others may increase the biochemical oxygen demand (BOD)
and consequently lower the dissolved oxygen in receiving
waters, causing suffocation and death of many aquatic species.
Still others may impart objectionable taste and odors to
drinking waters, a less harmful but certainly undesirable effect.8
In organic compounds also have many adverse effects on man
and the environment. Toxic heavy metals tend to concentrate in
the fauna and flora of the aquatic environmental and produce a
variety of effects in man once they are ingested. For example,
cadmium, besides being a carcinogen, has been linked to kidney
ailments, hypertension, and other cariovascular conditions;
hexovalent chromium is toxic and carcinogenic to both man and
organisms found in the aquatic environment; mercury concen-
trates in the human fetus and causes permanent fetal brain dam-
age; and silver produces a permanet blue-gray discoloration of
the skin and becomes toxic if allowed to accumulate.4,6,10
The National Space Technology Laboratories (NSTL), Bay
St. Louis, Mississippi, has the problem of treating chemical and
photographic waste products that contain a variety of organic
compounds as well as silver and trace amounts of such metals as
cadmium and chromium. Public Health Service (PHS) recom-
mendations for maximum discharge levels of some heavy metals
are presented in Table I.
Present techniques for treating photographic wastewater
include package activated sludge plants and aerobic lagoons.6
Heavy metals can be removed with varying degrees of efficiency
by chemical precipitation, electrodeposition, solvent extraction,
ultrafiltration, ion exchange and activated carbon absorption.3
Mixed wastes such as the wastes discharged at NSTL would
require a combination of these treatment techniques. All of
these methods are expensive to install and maintain and do not
always meet EPA standards.
In an effort to develop a relatively inexpensive and effective
means of treating the chemical and photographic waste at
NSTL, the National Aeronautics and Space Administration
(NASA) has installed a water hyacinth filtration system. The
water hyacinth, (Eichhornia crassipes) (Mart.) Solms, is an
excellent candidate for a biological filtration system for a
number of reasons. Water hyacinths possess an extensive root
system which allows them to feed directly from the aqueous
medium, extracting chemicals and nutrients rapidly and effi-
ciently. In experimental sewage and chemical treatment sys-
tems, water hyacinths have demonstrated the ability to substan-
tially reduce the concentrations of organics, minerals, and heavy
metals in the effluent waters.7,9,12-" Another feature is the
plant's tremendously high growth rate. Capable of producing
17.5 metric tons of wet biomass per hectare per day under ideal
growing conditions18, the water hyacinth is believed by many
botanists to be the most productive plant on earth.1 These
features, which make the water hyacinth such a successful pest
species, can also be of great potential benefit to man when the
plants are properly utilized.
Table I: Public Health Service Recommendations for Maxi-
mum Discharge Levels of Heavy Metals
Metal
Maximum Discharge Level, mg/£
Lead
0.05
Silver
0.05
Cadmium
0.01
Chromium
0.05
Description of the Water
Hyacinth Treatment System
A specially designed lagoon was constructed at the National
Space Technology Laboratories by NASA for the treatment of
photogrpahic and chemical laboratory waste. The lagoon was
constructed in a zig-zag configuration with the following
specifications: length, 332 m; width, 6.4 m; depth, 0.78 m; total
volume 1,675,000 liters; total surface area, 0.22 ha (See Figure
1). The zig-zag design promotes efficient filtration by maximiz-
ing the lagoon's length within a relatively small area. In
addition, this design facilitates access of harvesting machines to
the water hyacinths.
This lagoon receives approximately 95,000 liters per day. A
minimum retention time of 20 days was built into the system,
assuming that this would be the maximum time during the
-------
206 Water Hyacinths
winter months in which the plants wouid be metabolically
inactive.
In May 1975, this system was stocked with sufficient water
hyacinths to cover approximately 20 percent of the surface area,
and the waste from the chemical photographic laboratories was
diverted into the lagoon. Although chemical waste was the sole
source of nutrients available to the plants, they grew rapidly,
multiplying to 75 percent coveragg within four weeks. During
the summer months, the water hyacinths were sprayed with
malathion to control spider mites, (Brvobia praetiosa). The
plants thrived during all months of the experiment with the ex-
ception of January and February, when freezing temperature
caused the tops of the plants to die back.
47. 45m
t
6. 4ni
\
INF I, IK NT
STOCKED WITH
WATER HYACINTHS
EFFLUENT
0. 78m DEEP
1,041,000 I TOTAL VOLUME
0. 22 ha TOTAL SURFACE AREA
igure 1: NASA/NSTL Water Hyacinth Chemical Waste
titration System
Methods
Daily grab samples were taken from the wastewater before it
entered the lagoon and from the effluent waters. Water samples
were analyzed for pH, dissolved oxygen (DO), total suspended
solids (TSS), total organic carbon (TOC), 5-day biochemical
oxygen demand (BOD5), total phoshporous, and chemical
oxygen demand (COD), according to Standard Methods."
Heavy metal content of water samples was determined with the
aid of an 1L Model 253 Atomic Absorption/Flame Emission
Spectrophotometer.
Over a six-week period, sample water hyacinths were taken
from the lagoon weekly and analyzed for heavy metals. Roots,
stems and leaves were analyzed separately to determine whether
the metals migrated to upper parts of the plants. These plants
were washed, dried in an ovenat 110°C for48 hours and ground
to an even, fine consistency in a Waring commercial blender. All
glassware was acid-washed prior to use. One gram samples were
weighed out and transferred to 100 ml Kjeldahl flasks. To the
flask was added 10 ml concentrated nitric acid, approximately
60 ml distilled water and boiling chips. The samples were
digested until only a clear solution and a fine residue remained.
The supernatant was filtered into 100 ml volumetric flasks and
diluted to volume. The solution was analyzed by atomic
absorption. A blank was digested with all samples and used as a
correction factor for any contaminants in the reagents that
might have been introduced.
Results
Table II shows a complete yearly analysis by month of the
influent and effluent waters of this system. Silver was the only
metal present in quantities sufficient to be noted. Traces of
other metals were occasionally detected in the influent waters,
but no other metals were found in the effluent. The water
hyacinths maintained the effluent pH between 6.8 and 7.8. The
dissolved oxygen remained above the generally accepted stan-
dard of 5 mg/1 all but one month. No algal blooms were
observed during these twelve months as indicated by the
relatively low suspended solids. The reduction in dissolved
solids varied from 29 percent to a high of 75 percent.
The concentrations of total Kjeldahl nitrogen and total
phosphorous were also reduced by large percentages, as indi-
cated in Table 11. The most significant demonstration of water
hyacinths biological filtration capabilities was the reduction of
BOD5. The chemical oxygen demand has also been reduced by
83 percent to 92 percent.
Table 111 shows the systemic uptake of the heavy metals that
were routinely detected in the influent wastewaters. Over a 6-
week period, water hyacinths accumulated these heavy metals to
concentrations several hundred times the initial levels. The
highest concentrations of heavy metals were found in the roots,
the site of uptake of these substances, but there was also a
significant accumulation in the plant stems and leaves.
Table III: Analyses of Water Hyacinths Before Introduction
n ¦ i
Concentrations, ppm U>ry Weight)
Leaves
Stems
Roots
Metal
Initial
Six Weeks
Initial
Six Weeks
Initial
Six Weeks
Exposure
Exposure
Exposure
Copper
17. 5
32
10.9
48
24.0
594
Lead
8.4
33
2.1
45
40.0
297
Silver
0.8
y
<0.1
36.0
113
Cadmium
<0.1
2
<0.1
10
<0.1
164
Chromium
<0.1
4
<0.1
12
I <0.1
286
-------
Water Hyacinths 207
Table II: Monthly Average Data of the Water Hyacinth Chemical Waste Filtration System
Months
pH
Ur»-solwd
Oxygon
mg//
I'oLlI
Suspended
Sol ills
"»«/»'
r-»t.
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trig
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silvi
mg/
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Total
Org;,nil
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lliorhem u al
dv\K«'n Dem.md
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1976
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Discussion
The water hyacinths proved to be a very effective filtration
system for cleaning wastewater containing a complex chemical
mixture. Organics, heavy metals and other elements were
effectively removed from the wastewater by plant root sorption,
concentration and/or metabolic breakdown (Table II). Trace
elements entering the lagoon system were effectively removed to
levels which comply with PHS recommendations.
Even the hardy water hyacinth is not immune to heavy metal
pollutants. Approximately every eight weeks during the
summer,-the leaf tips began to turn brown and curl, indicating
that the plants had sustained permanent metabolic injury from
the environmental pollutants. The damaged sections of water
hyacinths were harvested and piled nearby, since it is believed
that plants in this condition are no longer maximally efficient at
purifying wastewaters. When water hyacinths are used in per-
manent chemical waste treatment systems, periodic harvesting
of damaged and/ or saturated plants may be jiecessary if the
discharge of toxic heavy metals is very high.
Since the plant stems and leaves, as well as roots, were found
to contain heavy metals, no part of the harvested plants can be
used as feed or fertilizer. However, the harvested plants can be
used safely for the production of biogas. W hole harvested plants
(or remaining sludge, if biogas is produced) should be put in a pit
specially designed to eliminate ground water infiltration. Such a
pit is planned to be utilized at the NSTL zig-zag lagoon. Over a
period of years, the heavy metals in the pit may accumulate to
levels high enough that their extraction becomes economically
feasible. Such small "mining" operations—particularly of
silver—may prove to be an efficient method of recycling
valuable metals for industrial use.
Determining the optimal retention time for a system designed
to remove heavy metals is complicated by the fact that these
substances readily undergo chelation in the presence of the
organic chemicals also discharged into the system.2,5 Although
plants will rapidly take up metals in the ionized form, chelated
metals are not readily sorbed by the plant roots. Some chelates
are very stable and can be broken down only by active microbial
degradation. Once degradation has occurred, the plant roots
will readily sorb the free metal ions. More research is needed to
understand the time lag engendered by the process of chela-
tion/microbial degradation and the effect of this process on
determining the proper retention time for maximum removal of
heavy metals from the system.
CONCLUSIONS
As a result of the water hyacinth's demonstrated ability to
treat chemical waste effectively, the experimental lagoon system
has been permanently installed at NSTL.
In combination with microorganisms, aquatic plants such as
water hyacinths must be seriously considered in developing
filtration systems for removing trace toxic chemicals such as
heavy metals and carcinogenic organics. For large industrial
systems, use of the water hyacinth may be limited to warm
climates, but small volume operations should consider
greenhouse techniques for maintaining these plants. Additional
research and screening should be conducted with the numerous
chemicals found in industrial waste to establish chemical
concentration levels that the water hyacinth and other aquatic
plants can tolerate and remove.
REFERENCES
1. Bates, Robert P., and James F. Hentges, Jr., 1976,"Aquatic
Weeds—Eradicate or Cultivate?" Economic Botany, J0(1),
pp. 39-50.
2. Cotton, F. Albert, and Geoffrey Wilkinson, F. R. S.,
Advanced Inorganic Chemistry, Second Edition, Inter-
science Publishers, New York, 1966.
3. Dean, John G., Frank L. Bosqui, and Kenneth H.
Lanouette, June 1972. "Removing Heavy Metals from
Waste Water." Environ. Sci. Techno!., 6, p. 518.
4. McCall, J., 1971 "Building a Shorter Life", Environment,
13(2), pp. 2-8.
5. Mortell, Arthur E., and Melvin Calvin, Chelate Com-
pounds, Prentice Hall, Inc., New York, 1953.
6. "MultiprongedAttack on Photo Wastes", Nov. 1971.
Environ. Sci. Technol.. 5, p. 1084.
7. Rogers, H. H.andD. E. Davis, 1972."NutrientRemovalby
Water Hyacinth". Weed Science, 20(5), pp. 423-428.
8. Sax, Irving N., 1974, Industrial Pollution. VanNostrand
Reinhold Co., New York, Chapter 9, pp. 197-219.
9. Sheffield, C. W„ 1967. "Water Hyacinth for Nutrient
Removal". Hyacinth Control Journal, 6(11), pp. 27-30.
10. Shroeder, H. A., J. J. Balassa, and W. H. Vinton, 1965.
"Chromium, Cadmium and Lead in Rats: Effect of Life
Span, Tumors and Tissue Levels", J. Nutri., 86. pp. 51-66.
11. Standard Methods for the Examination of Water and
Wastewater, 13th Edition, 1971.
-------
208 Water Hyacinths
12. Steward, K. K., July 1970. "trient Removal Potentials of
Various Aquatic Plants", Hyacinth Control Journal, 8, pp.
34-35.
13. Sutton, David L., and R. D. Blackburn, 1971. "Uptake of
Copper by Water Hyacinth". Hyacinth Control Journal,
9(1), pp. 18-19.
14. Wolverton, B. C., 1975. "Water Hyacinths for Removal of
Cadmium and Nickel from Polluted Waters". NASA
Technical Memorandum TM-X-72721.
15. Wolverton, B. C., and R. C. McDonald, 1975. "Water
Hyacinths and Alligator Weeds for Removal of Lead and
Mercury from Polluted Waters". NASA Technical Memo-
randum TM-X-72723.
16. Wolverton, B. C\, R. C. McDonald, and J. Gordon, 1975.
"Water Hyacinths and Alligator Weeds for Final Filtration
of Sewage", NASA Technical Memorandum
I'M X 72724.
17. Wolverton, B. C. and R. C. McDonald, 1975. "Water
Hyacinths and Alligator Weeds for Removal of Silver
Cobalt, and Strontium from Polluted Waters". NASA
Technical Memorandum IM X 72727.
18. Wolverton, B. C., and R. C. McDonald, October 1976.
"Water Hyacinths for Upgrading Sewage Lagoons to Meet
Advanced Wastewater Treatment Standards: Part II"
NASA Technical Memorandum TM X-72730.
19. Wolverton, B. C., and Mary M. McKown, 1976. "Water
Hyacinths for Removal of Phenols from Polluted Waters".
Aquatic Botany, 2{3), pp. 191 201.
-------
Suitability of Clay Beds for
Storage of Industrial Solid
Wastes
Earnest F. Gloyna
The University of Texas at Austin
Austin, Texas
and
Robert L. Sanks
Montana Sate University
Bozeman, Montana
INTRODUCTION
The disposal of industrial wastes in carefully designed land
disposal sites is a practical solution. Properly designed landfills
can provide barriers which are passive in character and are not
dependent on active, energy consuming systems. The rate of
transport away from a disposal site can be controlled so that no
unacceptable environmental insult will occur.
The disposal problem of solid wastes or residuals is com-
pounded by: (a) increasing magnitude of waste generated each
year;21 (b) variety of materials that become refuse; (c) vast array
of chemicals that may eventually leak from containers and
burial sites; (d) difficulty of adequately sequestering waste to
inhibit leaching; (e) difficulty of monitoring landfill sites for
leachates; (f) variability of soils and their sorption capacitiesfor
leachates; (g) variability of permeability of soils; and (h)
reluctance of some dischargers to spend more money on
materials no longer useful.
The massive clay beds ofTexas offer characteristics whichare
excellent for waste containment and ultimate disposal. Clays
have the capacity to remove any residuals by sorption (either ion
exchange or adsorption), by neutralization and by retention of
precipitates. Clay masses may exhibit considerable buffering
characteristics. Furthermore, some residuals (cyanide, for ex-
ample) can be biologically degraded by soil bacteria. If, in
addition, a landfill is designed to minimize the movement of soil
moisture, the driving force for the transport of wastes may be
reduced to insignificant levels. These mechanisms for retaining
residuals combine to make clay masses effective barriers.
Objectives
This paper describes test procedures that may be used to
design solid waste repositories. Specifically, the objectives of the
study were to; (a) develop test procedures for measuring the
action of a broad number of potential soil pollutants; (b)
observe and report factors that affect repeatability and accuracy
of determinations; (c) study the transport characteristics of a few
diversified materials; and (d) assess the suitability of clay
formations as disposal sites.6
Scope
The project was limited to the following tasks: (a) batch tests
involving five different clays (Beaumont, Catahoula, Eagle
Ford, Midway, and Taylor) and aqueous solutions in three
concentrations of hydrochloric acid, sodium hydroxide, ace-
tone, acetaldehyde, benzene, phenol, lead chloride, mercuric
chloride, chromium chloride and DDT (using decane as a
solvent); and (b) column tests involving three selected clays
(Beaumont, Catahoula, and Eagle Ford) and aqueous solutions
of hydrochloric acid, sodium hydroxide, phenol, lead chloride,
and mercuric chloride.
Literature
Very little data are available which are specifically applicable
for the design of ultimate disposal facilities. The literature on
sorption of specific ionic species by clay is extensive, but specific
design data describing sorption of complex leachates and
transport of industrial wastes through clay masses are not so
well understood. The time required to conduct such studies are
very long, and if field studies are required, the task can become
very expensive. Also, the imperviousness of the clay and the
mechanisms of sorption are difficult to measure over longtime
spans because of other interfering phenomena. Chemical
reactions, biological oxidation and precipitation tend to obs-
cure some aspects of uptake, release and transport of specific
wastes wastes.
Design
Most of the literature on the design of landfills deals with the
qualitative aspects of site selection and management. Relatively
few discussions are found dealing with rational designs, based
either on sequestering or sorbing capabilities of clay masses for
waste chemicals or leachates and leacingrates. 1,3,8,14,15,17,2° j^e
Environmental Protection Agency (EPA) in its assessment of
damage incidence resulting from improper land disposal
appears to have included damages that were not recorded, not
reported, and not known.3 For example, the contamination of
groundwater was considered a damage incident even if the
groundwater was not used, because the potential for damage
was present for some future user. Hazardous wastes were con-
sidered to be those which may pose substantial or potential
hazard to the health of human or other living organisms because
of non-degradability, persistency, biological magnification,
toxicity, or detrimental cumulative effects. This classification
would include: toxic metals such as arsenic, chromium, lead,
mercury, and cadmium; toxic anions such as fluoride and
cyanide; and toxic organics such as pesticides, polychlorinated
biphenyls, other chlorinated hydrocarbons and industrial
solvents. Case histories of contamination have been cited but
few, if any, involved a properly engineered landfill.12
According to the EPA, disposal of chemical wastes should
include a proper definition of: (a) organic or inorganic chemical
form; (b) acute or chronic toxicity; (c) genetic effect; (d)
flammability; and (e) radioactivity. Also, it was reported that
leachate problems tended to become more severe where precipi-
tation exceeded evapotranspiration.4 Furthermore, the poten-
209
-------
210 Clay Beds for Storage
tial of a burial site to limit the migration of leachates included:
infiltration rate, filtering capacity, buffering capacity, adsorp-
tive capacity, distance to groundwater, and groundwater
movement pattern and rate.
Various types of control technologyforgoundwater contami-
nation have been proposed.2-1'' PVC and hypalon liners appear
to have prevented seepage from landfills and lagoons. The liners
varied from 10 mills (0.25 mm) to 20 mills (0.5 mm). Other liners
include 12- to 18-inch thick clay blankets, and asphaltic con-
crete.
To utilize clay beds as a viable means for the disposal of
industrial solid wastes, certain aspects of the waste and the clay
should be examined. Factors that should be considered are: pH
of the waste; general physical-chemical form and concentration
of the waste residual; volume of the waste; and clay bed
characteristics.11'22 The specific clay characteristics should
include bulk density, grain size distribution, mineral
composition, exchange capacity and resident exchangeable
ions. The hydrologic information should include location of
surface and groundwaters.
An important design aspect of a disposal site involves the
transport of leachate through the clay mass. Eleven soil factors
have been identified which affect water infiltration and runoff.
These characteristics include; soil structure, surface tension
forces which influence moisture movement, soil moisture
content, soil permeability, soil mineralogy, vegetative cover,
tillage effects, temperature of water and soil, entrapped air,
topography, and infiltration.
Leaching and Sorption
Documentation by research, field operations, hydrogeolo-
gists, engineers, and operators of landfills all appear to show
that leachate has not been a significant problem in properly
managed sanitary landfills. When leachate problems have
occurred, the fault lay in lack of engineered design9'16
A number of papers have been published that describe the
sorption of leachates and the transport of chemicals. However,
most of these studies have been based on laboratory tests or use
of topsoils and not in situ.s,7'"<'H
Materials
All of the clay beds selected for this study lie within reasonable
distances from the heavily industrialized coastal area of Texas.
The clays are representative in terms of composition, imper-
viousness, distribution and age. One of them, Catahoula clay,
provides the varrier for several existing disposal pits. Six clay
samples were used and these were obtained from near surface
locations, Figure 1.
Beaumont Formation
The Beaumont formation is Pleistocene in origin. It consists
of clay and fairly continuous lentils of sand. The Beaumont clay
attains a thickness of 600 feet. There is a good possibility that a
pit in this formation would expose a sand unit which would have
to be excavated and backfilled with compacted clay to prevent
seepage of possible leachates.
Catahoula and Fleming Groups
The Catahoula and Fleming groups are undifferentiated.
Both are Oligocene in origin and the major formations are the
Frio, Anahuac, Catahoula, Oakville, Fleming, and Lagarto. Of
these the Oakville formation is normally a sand unit. The
Fleming and Catahoula grade from sands to clays. The
remainder of the formations are normally clays but may contain
thin sand units. The Frio formation attains a thickness of 800
feet in some subsurface sections. The test sample was taken
either from the Frio formation or a clay fades of the Catahoula
formation, but in this report it is assumed to be Catahoula. In
this formation there is a moderate chance of intersecting a sand
unit with an excavation.
Eagle Ford Group
The Eagle Ford Group is a Cretaceous formation i
-non consisting
mostly of shales and limestone. In north Texas it is ne—1
shale, in south Texas it is almost all flaggy limestone,
central Texas it consists of interbedded shales and lirr
nearly all
and in
limestone
lags. The Eagle Ford group attains a thickness of 400 to 500 feet
in north Texas. There is little likelihood that an excavation in
this group would encounter a sand unit until the Woodbine
formation is penetrated.
Midway Group
The Midway Group is Eocene in origin, and the sample was
taken from the Kincaid formation. The Midway Group includes
mostly clay units with a few sand units and limestone lentils. It
reaches a thickness of about 800 feet. Pits in this material have a
moderate chance of intersecting a sand unit.
Taylor and Navarro Groups
These two groups are lithologically similar. They are Cretace-
ous in origin. The formation sampled was within the Taylor
group and is known as Ozan or, locally, as the Sprinkle
formation. The Taylor and Navarro are almost entirely shales
and marls. Combined, they attain a thickness of about 2,000
feet. There is little possibility that a pit in this formation would
intersect a sand unit.
Washita Group
The Washita group includes the Del Rio formation formed
during the Cretaceous Age. It consists mostly of limestones and
sandstones with only minor clay units. The only major clay or
shale in the Washita is the Del Rio or Grayson formation. The
Del Rio-Grayson attains a thickness of about 200 feet at most. It
is extremely thin in western Texas, except in Val Verde County.
There is little possibility that an excavation within the Del Ri0
would intersect sand, but there is a somewhat greater possibility
that it would hit a limestone unit which, like sand, might also
permit seepage.
Test Apparatus
Most of the apparatus was designed and constructed specifi-
cally for the project. The overall object was to keep test
equipment simple. Consequently, the development included
several stages and modifications.
Cores were obtained, where possible, by driving a core holder
with a sledge until an inner plastic liner was filled. Then, the cap
was removed; a yoke was attached; and the core holder pried out
of the ground with a pick.
Each of the clays were characterized according to standard
procedures. Specimens were compacted as prescribed by the
American Society for Testing Materials D698-70, and the
apparatus used in the determination of the liquid limit is de-
scribed under the American Association of State Highway
Officials Designation, T89-60. Carbonate analyses were made
by reacting soil samples with boiling one normal hydrochloric
acid to generate carbon dioxide which, after scrubbing, was
absorbed in a strong solution of sodium hydroxide.10 The X-ray
diffraction examinations were made using a General Electric
XRD-5 x-ray Diffractometer, 2 to 30 degrees at 1000 cycles per
second. Thus, the material in clays which have great impact
upon its characteristics may be identified. These particles are
mostly flaky or platy and are identifigd as illite or mica,
montmorillonite, kaolinite, vermiculite, and chlorite.
-------
Clay Beds for Storage 211
GZZZ3 COASTAL PLEISTOCENE FORMATIONS
^ CATAHOULA and FLEMING GROUPS
M MIDWAY GROUP
^ TAYLOR and NAVARRO GROUPS
^ EAGLE FORD GROUP
^ WASHITA GROUP
Figure 1: Surface Extent of Sampled Geological Groups
Cation Exchange Capacity
The clays were processed by: converting to sodium form with
excess sodium acetate, rinsing with several cycles of an alcohol
wash, and centrifuging after each wash.
The cation exchange capacity was determiend by measuring
eluted sodium following each of several cycles of treatment with
excess ammonium acetate and centrifugation. Sodium analyses
were made using a Baird Atomic Flame Photometer, Model
KY2.
Batch Data—Isotherms
Isotherms were developed using data derived from batch
tests. Soil samples were mixed with test solutions, vigorously
mixed, separated by centrifugation, and uptake of test solution
determined. Organic analyses were made using a Tracor Model
550 Gas Chromatograph fitted with a flame ionization detector.
Heavy metal analyses were made using a Perkin-Elmer Atomic
Absorption Spectrophotometer Model 303.
Column Tests
The need for versatility, economy, and a large number of test
requirements led to several column designs. One column
assembly was designed to accept an"undisturbed" clay core. An
overburden load was simulated by preloading the soil sample
with a weight placed on a porous dish. This assembly was later
modified because the unit required machining, parts were not
readily obtainable, and the specimen could not be examined
visually.
In a second design, machining was not critical, the unit cost
was small, and the sample was always visible. Also, the unit was
compact and the system was adaptable to a wide range of test
conditions.
Clay Characterization
The grain size distribution shown in Table I indicated high
clay content.
Table I: Grain Size Distribution
Clay
Slit
Sand
Material
<*)
<*)
{%)
Beaumont.
58.3
40.5
1.2
Catahoula
38.2
54.2
7.6
fcnqle Ford
46.9
41'. L
12.0
Midway
55.9
42.9
1.2
Taylor
64. 5
28.4
7 .1
Del Rio
57.2
36.5
4.3
Table II: Atterberg Limits
Material
Plastic Limit
moisture
(%)
Liquid Limit
moisture
{%)
beaumont
32.9
B0
Catahoula
43.3
85
Eagle Ford
24.2
54
Midway
44.5
75
Taylor
30.0
71
Del Rio
25.5
73
-------
212 Clay Beds for Storage
Except for Del Rio clay, samples were classified as being
predominantly calcium montmorillonite, Table 3. Montmoril-
lonite is highly sorptive in contrast to illite which does not have
high sorptive or ion exchange capacities. The Catahoula clay
gave a very poor diffraction pattern.
Table IU: Mineralogy of Clays
Type; of C lay
U)
Calcium
Montmon 1 -
lonite
Beaumont
Catahoula
Ea
The data appear to show that CEC increases with increasing per-
cent of montmorillonite and decreasing percent of carbonate.
Similarly, it seems that if two clays with the same percent of
montmorillonite were checked for CEC the one with the lowest
percent of carbonate would exhibit the highest CEC.
Containment of Waste
After the physical-chemical characteristics of a clay bed and
the wastes have been determined, it is then necessary to evaluate
the relative movement of the waste if a driving force should
occur. As in all experimental work, tests must be conducted with
care. For example, many organic compounds are relatively
volatile, while heavy metals, notably lead, may form insoluble
carbonates.
Permeability
Permeability, based on deionized water in high density
columns, varied from 1.6 * 10 H cm/sec for Eagle Ford clay to
0.13 * 10 * cm/sec for Beaumont clay. Low density columns
exhibited permeabilities ol 4 * 10 K to 12 * 10 * cm/ sec,
respectively, lor acid and basic wastes. Heavy metals exhibited
little effect on permeability, excepting Beaumont clay where the
effect of the salt was to increase the permeability.
Isotherms
Data from all of the batch tests fit the Freundlich type
isotherm. Examples are shown in Figures 2 and 3 for mercury
and phenol. In general, acetaldehyde, acetone, and phenol
exhibited about the same adsorption patterns. At an equili_
brium fluid concentration of 0.1 mole Titer, the range of
adsorption for the organics varied from 1 to 90 mM / kg of clay.
All of the clays sorbed or reacted with approximately 40q
mM/kg of hydroxyl ion. Eagle Ford clay provided the largest
sorption for mercury.
Column Tests
Breakthrough histograms can be interpreted by determirftng
the capacity of the clay utilized when a given breakthrough
concentration is attained. An example is presented in Table V|,
Acid disrupted all clay columns while caustic caused the clays to
swell and become more impervious. Histograms of break-
through curves under various test conditions showed through,
put ratios (unit volume of liquid per unit volume of clay) to vary
from one to three or more before 50 percent breakthrough
occurred. Histograms depicting heavy metals uptake were more
erratic.
A Design Concept
When it is impossible to delineate all waste materials mate-
rials, reaction rates, environmental factors and political con-
straints, it is probably best to adopt a design for the disposal of
industrial solid wastes which embraces the multiple barrier
concept which is as passive as possible. Such a system might
logically include evaluation of: (a) transport container, if any
(basically a temporary containment unit); (b) compartmental-
ized system (the size is subject to other factors); (c) reconstituted
and reworked clay liners for compartmental walls where needed
(thickness and compaction subject to type of waste); (d)clay bed
(type of clay and size of clay bed important for some waste); and
(e) elimination of water (water provides the driving force f0r
transporting waste through the compartment, clay bed, other
geological formation and ultimately the biosphere).
Figure 4 depicts a generalized area and layout for an
industrial landfill. The reconstituted clay liner may vary from
several inches to several feet, depending on the waste, surround-
ing clays, water conditions, and other factors unique to the
waste and area. The cross section of the pit may take several
forms, depending on the techniques used to open the pit, prepare
the liner areas, fill the pit, and close the compartments.
All of these details should be defined clearly in the engineering
report accompanying a request for industrial solid waste dispo_
sal.
None of the wastes will migrate significantly if there is no
liquid driving force. However, if it is assumed that water
enter through the passive barriers then sorption and transp0rt
become critical in the design of an industrial disposal site.
ACKNOWLEDGMENT
This project was supported in part by the Texas Water
Quality Board, Hugh Yantis, Executive Director.
-------
Clay Beds for Storage
Table VI: Capacity of Clay Utilized in Column Tests Before Significant Breakthrough Occurred
213
Clay
Metal Ion
Breakthrough
Throughput
Amount Not
Amount
Theoretical
Percentage of
Type
Solution
Criterion
Sorbed
Sorbed
Capacity
Clay Utilized
(C/CQ Value) *
(lAg clay)
(mMAg clay)
(mMAg clay)
(mMAg clay)
(%)
Beaumont
Lead
0.1
7.6
14
214
265
80
Mercury
0.7
3.0
42
18
265
7
Catahoula
Lead
0.1
4.5
13. S
121.5
260
44
Mercury
0.1
2
6
56
280
20
Eagle Ford
Lead
no breakthrough
100
greater than 100
Mercury
0.1
4.0
120
100
120
*Ratio of concentration "C" at any time to initial concentration "C0".
O
<0
E
3
3
CT
UJ
0.1
.01
Figure 2: Phenol Isotherms
Catahoula
Taylor
Beaumont
Midway
I 10
Equilibrium Fluid Concentration,(mM/l)
100
1000
REFERENCES
1. Battelle Memorial Institute, Program for the Management
of Hazardous Wastes for Environmental Protection
Agency, Final Report, Office of Solid Waste Management
Programs, Richland, Washington, 1973.
2. Dallaire, G., "Tougher Pollution Laws Spur Use of Imper-
meable Liners," Civil Engineering, 45, 5, 63, 1975.
3. Eye, J. D., "Aqueous Transport of Dieldrin Residues in
Soils," Proceedings 26th Industrial Waste Conference,
Purdue University, Lafayette, Indiana, 1023, 1968.
4. Farb, D., "Land Disposal Technology for Industrial
Wastes," Proceedings of the National Conference on
Management and Disposal of Residues from the Treatment
of Industrial Wastewater, Information Transfer, Inc., 6110
Executive Boulevard, Rockville, Maryland, 225-231,1975.
5. Guisti, D. M., Conway, R. A., and Lawson, C. T.,
"Activated Carbon Adsorption of Petrochemicals," Jour-
nal Water Pollution Control Federation, 46, 5, 947-965,
1974.
6. Gloyna, E. F„ Sanks, R. L. and La Plante, J. M„ Survey-
Suitability of Clay Beds for Storage of Industrial Solid
Wastes, Center for Research in Water Resources Report
No. 128, The University of Texas at Austin, 79 pp., 1975.
7. Gloyna, E. F. and Gromiec, M. J., Radioactivity Transport
in Water—final Report, Center for Research in Water Re-
-------
214 Clay Beds for Storage
300
I 10
Equilibrium Fluid Concentration (mM/I)
Figure 3: Mercury (II) Isotherms
•Poo
B'J- +^A'
PLAN VIEW OF CLAY PIT
GROUND SURFACF
OVERBURDEN
CLAY 8 SOIL
SCHEMATIC OF GENERALIZED AREA
;lay LINER
CROSS SECTION B-B1
TRAPEZOIDAL COMPARTMENT
CROSS SECTION D-D'
CLAY
LINER
SOLID
WASTE
'/.Va-/, CROSS SECTION A-A'CUBICAL COMPARTMFmt
CLAY
LINER feL-fl
SOLID
WASTE
WW
(TYPE B SLOPING WALL) CROSS SECTION C-C'(TYPE A VERTICAL Waj, }
gure 4: Schematic of Industrial Solid Waste Disposal Site (Reconstituted Clay Liner or Blanket Only Where Needed)
-------
Clay Beds for Storage 215
sources Report No. 97, The University of Texas at Austin,
71 pp., 1973.
8. Hajek, B. F., "Chemical Interactions of Wastewater in a
Soil Environment," Journal Water Pollution Control
Federation, 41, 1775 1786, 1969.
9. Ham, R. K. and Boyle, W. C., "Biological Treatability of
Landfill l.eachate," Journal Water Pollution Control
Federation. 46, 5, 860 872, 1974.
10. Jackson, M. L., Soil Chemical Analysis, Prentice Hall,
Englewood Cliffs, New Jersey, 1964.
11. Kaufman, W. J., "Chemical Pollution of Ground Waters,"
Journal American Water Works Association, 66, 3, 152,
1974.
12. Lazar, E. C., "Summary of Damage Incidents from
Improper Land Disposal," Proceedings of the National
Conference on Management and Disposal of Residues
from the Treatment of Industrial Wastewaters, Informa-
tion Transfer, Inc., 6110 Executive Boulevard, Rockville,
Maryland, 1975.
13. Leighton, I. W., "Removal of Cations from Leachate by
Subsurface Soils," Journal Boston Society of Civil Engi-
neers, 60, 4, 145, 1973.
14. Lindstrom, F. T., "Theory on the Movement of Some
Herbicides in Soils, Linear Diffusion and Convection of
Chemicals in Soils," Environmental Science and Technol-
ogy, I, 7, 561, 1967.
15. Makela, R. G., and Malina, J. F., Solid Wastes in the
Petrochemical Industry, Center for Research in Water Re-
sources Report No. 92, The University of Texas at Austin,
1972.
16. McGauhey, P. H., Glysson, E. A., and Ham, R. K.,
"Sanitary Landfills: The Latest Thinking," Civil Engineer-
ing, 43, 3, 69 71, 1973.
17. Qasim, S. R., and Burchinal, J. C., "Leaching of Pollutants
from Refuse Beds," Journal Sanitary Engineering Divi-
sion, Proceedings American Society of Civil Engineering.
96, SA1, 49-58, 1970.
18. Reimer, D. N„ and Toth, S. J., "Adsorption of Copper by
Clay Minerals, Humic Acid and Bottom Muds," Journal
American Water Works Association, 62, 3, 195, 1970.
19. Remson, L, et al., "Water Movement in an Unsaturated
Sanitary Landfill," Journal Sanitary Engineering Divi-
sion, Proceedings American Society of Civil Engineering,
94, SA2, 307. 1968.
20. Saxton, J. C. and Kramer, M., "EPA Findings on Solid
Waste from Industrial Chemicals," Chemical Engineering,
82, 9, 107, 1975.
21. Sherman, J. S. and Malina, J. F., Water Needs and
Residuals Management, Center for Research in Water
Resources Report No. 112, The University of Texas at
Austin, 1974.
22. Schwartz, W. A. and Bendixen, T. W., "Soil Systems for
Liquid Waste Treatment and Disposal: Environmental
Factors," Journal Water Pollution Control Federation, 42,
5, 624, 1970.
-------
A Nitrate-Removal
Ion-Exchange Process
with a
Land-Disposable Regenerant
Dennis A. Clifford
The University of Houston
Houston, Texas
and
Walter J. Weber, Jr.
The University of Michigan
Ann Arbor, Michigan
INTRODUCTION
Although the multicomponent ion-exchange research de-
scribed here was done specifically to improve the operating
efficiency and eliminate the residue disposal problems in nitrate
removal from public water supplies, the findings are rather
universal and directly applicable to industrial ion-exchange
processes in general.
It is anticipated that the provisions of the U.S. Safe Drinking
Water Act of 1974 (Public Law 93 -523) will apply to all public
water systems in mid 1977. Incorporated into that act is a
provision which, when it takes effect, will legally limit the
concentration of nitrate as nitrogen to 10 gm/1'5. This level is
equivalent to the long-standing, recommended limit established
by the U.S. Public Health Service for the prevention of
methemoglobinemia in infants. Public and private water supp-
lies in nearly all of the fifty states and in many foreign countries
have been found to be polluted with nitrates in amounts regu-
larly exceeding this 10 mg/1 limit. Nitrate removal by ion
exchange with synthetic, organic, anion-exchange resins is the
treatment method which appears to offer the most readily
available, proven technology at a cost which is not unreason-
able. However, disposal of the spent nitrate-containing,
regenerant-brine solution is an unsolved problem and, previous
to the time of this research, there was a lack of technical
information in the literature regarding the selectivity of the
various anion exchange resins for nitrate with respect to the
important ground-water anions: chloride, sulfate and bicarbo-
nate. Neither was there sufficient, useful information available
for the prediction of multicomponent effluent concentration
profiles from ion-exchange columns economically operated by
chromatographically eluting the ions not intended to be
removed.
The research described here was undertaken to provide the
missing data and to propose hypotheses concerning the predic-
tion and control of anion exchange selectivity in general. A
further objective was to provide a means of describing the
multicomponent chromatographic column behavior of anion-
exchange resins, especially weak-base resins, in nitrate removal
service. A final objective was to perform technical and econom-
ic evaluations comparing a conventional, single-bed, strong-
base, nitrate removal process to a two-bed, strong-acid, weak-
base, nitrate removal process which would produce a spent
ammonium nitrate regenerant amenable to disposal as a fertil-
izer.
Ion-Exchange Processes Studied
The Single Bed Process
The "usual"1,7,8,12 and conceivably the most economical
means of nitrate removal from dilute solutions (^0.06 N) using
ion-cxchangc is a single-bed (fixed or moving) strong-base
anion exchanger in the chloride form as described in Figure 1.
With a typical ground water having the analysis shown, at least
25% of the feedwater may be safely bypassed and still provide a
water of acceptable nitrate concentration (5 10 mg/1) right up
until nitrate breakthrough. Offsetting the inherent economical
advantages of the process are the following serious disadvan-
tages.
— Row Woter Influent
Flow = 0
Nitrate-N = 20 mg/1
TDS = 380 mg/1
Hardness = 225 mg/1
NaHC03
Co(NOj)2
MgSQ,
CaCI2
Fe S04
I
Regenerant
NaCI
(low cost)
0.25 Q
Strong
Base
Anion
Exchanger
Chloride
Form
Ion Exchange Column
Effluent __
Cq CI2
MgCI2
NaCI
Fe CI,
I
Bypass k
0.75 Q
Raw r
Water j
Spent Regenerant
NaCI - NaNOj Brine
(Disposal Problem)
-Blended Product Wm..
Nitrate -N =5-10 mg/|
TDS = 296-380 mg/|
Hardness - 225 mg/|
Chloride = 53-195 mg/|
Figure 1: Conventional Single Bed Ion Exchange Process
216
-------
Ion-Exchange Process 217
(1) Resin selectivity for nitrate is a potentially serious
problem because sulfate is expected to be preferred with a
selectivity ratio of more than 2/ 1 over nitrate.
(2) Ferrous iron when present oxidizes, precipitates and
seriously fouls the resin.
(3) Regeneration and brine disposal are the major economic
and environmental problems yet to be solved even with low-cost
NaCl regeneration.
The Two-Bed Strong-Acid Weak-Base Process
Because this two bed process seemed to have certain advan-
tages with respect to regeneration efficiency, iron removal,
regenerant disposal as fertilizer and nitrate selectivity, the little-
studied weak-base resin portion of the two-bed system shown in
Figure 2 was examined in detail. The thermodynamic and
kinetic data from the weak-base resin studies were compared
and contrasted to the data obtained from strong-base resins of
the type used in the single-bed process shown in Figure 1.
-Row Water (Typical) I
Flow » 0 NH40H|
Nitrate-N* 20ppm Regenerant|
TDS =380ppm i
Hardness *225 ppm ,
NaHCOj
Ca(N0j)2 I HNOs Regenerant I
Mq S0« I f Alternatively,1 '
NH,N0,
(Fertilizer)
<>-Ion-Exchange
Column Flow ¦ .75 Q
Blended
Product Water
N itrate - N ¦ 5 -tOppm
TDS»95 -380 ppm
Hardness "56-225
, ppm
Figure 2: Proposed Two-Bed, Ion-Exchange Process
Evans5 reported on a similar two-bed nitrate removal process,
but with HC1 and lime as th? regenerants. He pointed out that,
even after the cation bed was exhausted, and sodium was being
eluted, the system continued to provide softening and nitrate
removal thereby delivering greater than stoichiometric
efficiency due to the weak-base anion resin's selectivity for
nitrate over all the other ions present including sulfate. Actually
in the total concentration range experienced with water supplies
(0.002 to 0.01 N), nitrate is thermodynamically not the most
preferred ion. The often reported sequence for both strong and
weak-base resins is1,4,5,9,14.
Sulfate >nitrate >-chloride >bicarbonate
In this concentration range, both cation and anion exchangers
of the synthetic organic resin type much prefer divalent over
monovalent ions (although carbonate is an exception, it being
less preferred than nitrate). This preference for the multivalent
ions has been termed "electroselectivity"<,.
Experimental
Theory
With the selectivity sequence listed above, multicomponent
chromatography theory10,1',11, 14 can be used with some simpli-
fying assumptions to predict the resin-phase concentration
profile of the anion exchanger used in Figures 1 and 2. A
hypothetical, semiquantitative profile showing the idealized dis-
tribution of sulfate, nitrate, chloride and bicarbonate is given in
Figure 3. The assumed test water for resin exhaustion had the
anion composition of the water in Table II. The most preferred
species, sulfate, is removed preferentially and is concentrated
near the inlet to the column. Bicarbonate, the least preferred
species, is removed nearer to the exit end of the column and is
the first ion other than the exchanging ion to show up in the
effluent. Quanitifcation of the breakthrough curves for all the
ions may be approximated if the selectivity coefficients or
separation factors (a's) are known for the ions of interest",13.
These constants are defined below for an example
sulfate/nitrate ion-exchange reaction on a typical anion resin:
K
2 RN03 + SO4 Z R2SO4 2N03
Selectivity [R2SO4I [N03]2
N
S
(
N
S
C
N
where:
Coefficient
[S04] [RNO3]-
= Separation Factor = Z?. . ^
XS XN
N
^ _N
3 yN
R2SO4
SO4
[ 1
>s
xs
-o
sulfate in the resin phase
sulfate in the liquid phase (water)
denotes concentration in eq/1
equivalent fraction sulfate on the resin
equivalent fraction sulfate in the water
Total conc. of liquid phase in eq/1
Total capacity of the resin in eq/1
K and a can be determined from constant temperature plots of
resin phase concentration vs water phase concentration of the
ions being exchanged—a binary ion-exchange isotherm (see
Figures 4-6). One important objective of the research was to de-
velop sulfate/nitrate and chloride/nitrate isotherms for all the
commercially available strong and weak-base anion exchangers
manufactured in the U.S. Column two of Table I contains a
listing of all the resins obtained for the research study.
-------
218 Ion-Exchange Process
Table I: Phase I Data Summary Anion Resin Characteristics
UM RESIN NUMBER
MANUFACTURER'S
DESIGNATION
1
j
i
MATRIX
FUNCTIONALITY
POROSITY
Meq/ml
ADVERTISED
CAPACITY
Meq/ml
MEASURED
HC1 CAPACITY
1
pKa
AVERAGE
S
aN
AVERAGE
N
aci
15
AMBERLITE IRA-40C
STY-DVB
Q-1
MICRO
1 .40
1 .53
>13
1.89
—
17
AMBERLITE IRA-90C
STY-DVB
Q-1
MACRO
1 .00
1 .10
>13
1 .-71
3 .41
21
DOWEX SBR
STY-DVB
Q-1
MICRO
1.40
1.66
>13
1.89
2 .90
27
IONAC ASB-1
STY-DVB
Q-1
MICRO
1.40
1.39
>13
1.87
32
IONAC AFP-100
STY-DVB
Q-1
MACRO
1.20
1 .07
-13
1.76
2.97
16
AMBERLITE IRA-40C
STY-DVB
Q-1
ISO
1.25
1 .16
>13
3 .09
3 .11
19
DOWEX SBR-P
STY-DVB
Q-1
ISO
1 .20
1.02
>13
2 .96
22
DOWEX 11
STY-DVB
Q-1
ISO
1 .20
1 .17
>13
3.37
—
24
DUOLITE A-101-D
STY-DVB
Q-1
ISO
1 .30
1 .32
>13
2 .59
-
28
IONAC A-641
STY-DVB
Q-1
FM
1 .16
1.21
>13
3.33
3.33
30
IONAC ASB-1P
STY-DVB
Q-1
ISO
1 .35
1 .13
>13
2 .59
-
14
AMBERLITE IRA 910 STY-DVB
Q-2
MACRO
1 .00
1.31
>13
3.26
2 .85
18
AMBERLITE IRA 410 STY-DVB
Q-2
MICRO
1 .35
-
>13
2.40
—
20
DOWEX SAR
STY-DVB
Q-2
MICRO
1.40
1.50
>13
3 .04
_
23
DUOLITE A-102-D
STY-DVB
Q-2
MICRO
1.40
1 .48
>13
3.26
—
29
IONAC ASB-2
STY-DVB
Q-2
MICRO
1 .52
1.33
>13
3.04
3 .64
1
AMBERLITE IRA-93
STY-DVB
TERTIARY
MACRO
1 .25
0.98
7.7
3.75
4 .86
5
DOWEX MWA-1
STY-DVB
TERTIARY
MACRO
1.10
1 .15
7 .6
2.67
4.43
8
DUOLITE ES-368
STY-DVB
TERTIARY
MACRO
1 .30
1 .43
7.8
2.83
3.87
12
IONAC AFP-329
STY-DVB
TERTIARY
MACRO
1 .25
1 .26
8.5
3.07
4.14
3
AMBERLITE IR-45
STY-DVB
POLY
MICRO
1.90
1 .76
7 .9
12.7
3 .89
2
AMBERLITE IRA-68
ACRYLIC-AMINE
TERTIARY
MICRO
1 .60
1 .42
11 .1
23.4
1 .89
10
DUOLITE ES-374
ACRYLIC-AMINE
POLY*
MACRO
3.0
2 ,59
9 .9
94.0
3 .85
6
DUOLITE A-7
PHENOL-HCHO-PA
POLY**
MACRO
2 .4
1.67
7 .7
108
3.35
9
DUOLITE ES-561
PHENOL-HCHO-PA
POLY
MACRO
2.0
1.22
6.8
109
2 .65
11
IONAC A-260 ALIPHATIC-AMINE
POLY
MICRO
1.8
1.81
10.6
54 .0
2.25
4
DOWEX WGR
EPOXY-AMINE
POLY
MICRO
1.0
1 .53
7.9
137
1 .99
7
DUOLITE A-34 0
EPOXY-AMINE
POLY
MICRO
2.6
2 .54
8.7
82 .9
1 .70
13
IONAC A-305
EPOXY-AMINE
POLY+
MICRO
3.5
1 .51
108
POLY = Polyamine not including quaternary amine
Q-1 = Quaternary Amine - Type I
Q— 2 = Quaternary Amine - Type 2
IgO = Isoporosity or "Improved Porosity"
FM = Fixed Macropore (MANUFACTURER'S TERMINOLOGY)
POLY* = Advertised as tertiary amine but titrates as polyamine
POLY** = Advertized as secondary amine but titrates as polyamine
POLY+ = Polyamine including quaternary amine
-------
Ion-Exchange Process 219
10
0.0
Vs. i
so.
yw.i
ZONE 1
(Sulfate)
N03
rCI,1
CI
NO,
ZONE 2
(Nitrate)
'ci, ?.
CI
^01,3
~7
ZONE 3
(Chloride)
Vb,4
ZONE 4
(HCO3)
0.0 ¦
00-•
ml of Resin
-5.0
meq Exchanger/meq Soln.-
Figurc 3: Resin Phase Concentration Profile
-1.0
. SULFATE-N1TRATE
. CHLORIDE-NITRATE
^.00 0.20 O.HO 0.60 0.80 1.00
*sou. EQUIVHLENT FRACTION S0u IN LIQUID PHASE
*a., EQUIVALENT FRACTION CL IN LIQUID PHASE
RESIN NUMBER 8
DUOLITE ES 368, MACROPOROUS RESIN
STYRENE-DVB MATRIX
TERTIART-AMINE FUNCTIONALITY
TOTAL CflPflCITT=1.3 MEQ/ML
Figure 4: 25° C, Binary Ion-Exchange Isotherm
Selectivity Studies
The experimental sulfate/nitrate isotherms were constructed
by equilibrating (for 16 hrs) weighed samples of resins in the
nitrate form with 0.005 N H2S04 solutions and measuring the
redistribution of ions (ion exchange) which took place. At least
five data points were obtained for the construction of each
isotherm with each of the 32 resins. Nitrate/chloride isotherms
were determined for 20 of the resins using essentially the same
technique. Bicarbonate/nitrate selectivity studies were also
conducted on 12 of the resins.
Ion Exchange Column Studies
When the equilibrium data described above were partially
evaluated, resins were selected for laboratory scale (1" dia by
24" deep) column experiments in which the chromatographic
elution of ions was to be observed and hopefully quantified with
the help of the experimentally determined separation factors. A
simulated ground water (see Table II) was used in most of these
studies. Ten of the eleven multicomponent column runs were
made with the two-bed system described in Figure 2 as simulated
by the experimental flow system shown in Figure 7. One
comparison run was made with the single-bed system described
in Figure 1 by simply bypassing the cation column shown in
Figure 7. Complete experimental details, resultsand analysis for
both the selectivity and column studies can be found in
Reference 3.
^.00 0.20 0.40 0.60 0.80 1.00
*50^. EQUIVALENT FRACTION SOh IN LIQUID PHASE
*CL, EQUIVALENT FRACTION CL IN LIQUID PHASE
RESIN NUMBER 3
AMBERLITE IR US. MICR0P0RDUS GEL
STYRENE-DVB MATRIX
POLYAMINE FUNCTIONALITY
TOTAL CAPACITY=1.9 MEQ/Ml
Figure 5: 25°C, Binary Ion-Exchange Isotherm
O SULFATE-NITRATE
. CHL0RI0E-NITRATE
"^>.00
0.20 o.to 0.60 r.ao 1.00
EQUIVALENT FRACTION SO,, IN LIQUID PHASE
EQUIVALENT FRACTION CL IN LIQUID PHASE
RESIN NUMBER 4
DOWEX WGR, MICROPOROUS GEL
EP0XY-AMINE MATRIX
POLYAMINE FUNCTIONALITY
TOTAL CflPACITY=l.0 MEQ/ML
Figure 6: 25° C, Binary Ion-Exchange Isotherm
-------
220 Ion-Exchange Process
Table II: Phase II Data Summary Column Performance Characteristics
*
Flow
Minimum
Bed
* *
Final
Column
®
Run
No .
gal ,
min•ft
Final
PH
Depth
cm
Resin Description
(Cation Regeneration Level)
S
%
N
aci
*C1
yso4
YHC03
yN03
Capacity
meq/ml
ve
BV
1
2 . 34
2.5/2.5
63.5
Duolite ES-368
STY-DVB, Tert-Araine, MR
2 .8]
3.87
.13
.53
. jO
.34
1.65
582
2
4 .88
2.5/2.5
30 .5
Duolite ES-374
Polyacrylic, Polyamine, MR
94 .
3.85
.26
. 36
.02
.36
2.93
720
3
4 .88
2.4/2.4
30.5
Duolite ES-368
STY-DVB, Tert. Amine, MR
2.83
3.87
.20
.40
.01
.39
1 .36
364
4
4.88
2.5/2 .5
30.5
Dowex WGR
Epoxy-Amine, Polyamine, Gel
137.
1 .99
.27
.37
.00
. 36
1.62
391
5
2.44
2.4
2.4
61 .0
Duolite ES-368
STY-DVB, Tert. Amine, MR
2.83
3 .87
.16
.43
.00
.41
1.48
423
6
2.44
2 . 3
2 .5
61.0
Duolite ES-374
Polyacrylic, Polyamine, MR
94 .
3.85
.15
.44
.00
.41
3.12
920
1
2.44
6 .1
7.4"
61.0
Ionac AFP-329
STY-DVB, Quat . (I)Amine, MR
1 .76
2.97
.14
.43
.01
.42
1.03
295
8
2.88
2 .8
5.8
61 .0
Duolite ES-368 (600%)
STY-DVB, Tert. Amine, MR
2 .83
3 .87
.21
.40
.00
.39
1 .39
375
9
2.44
4 .5
6.7
61.0
Duolite ES-368 (120o)
STY-DVB, Tert. Amine, MR
2.83
3.87
.31
. 34
.02
.33
0 .84
190
10
2.44
4 .6
6.3
61 .0
Duolite ES-368 ( 2 4 0)
STY-DVB, Tert. Amine, MR
2.83
3 .87
.14
.44
.00
.42
1.15
334
11
2.44
4 .7
5.5
CI .0
Amberlite IR-45 (3001)
STY-DVB, Polyam.ine, GEL
12.7
3.89
.08
.45
.03
.44
1.61
4 an
—
gal/min-ft x 7.48 - Superficial Detention time, «e, minutes
*Ve = Bed Volumes of Effluent to 0.5meq/l NO^-Breakthrouyh (end of run)
** Final Column Capacity is greater than measured HC1 capacity because resin has hiaher capacity
for sulfate which occupies a significant fraction of the available sites at the end of the run
-CX3-
Two
Piexiglas
Columns
2.54cm I.D.
1,52 m. long
Resin Depth
61 cm (Typ.)
Feed water
Pump
0-450 ml/min
1001
Artificial
Ground-
water
To Waste
L
Acid Pump
0-50 ml/min
0o°o°°sn Automatic Sampler
°oo ooS-
(24; 500 ml Bottles)
NH40H Pump
0-20 ml/min
4%
NH40H
1.14 N.
pH Meter
Strip Chart Recorder
t*3= N. 0. Valve
Ms N. C. Valve
igure 7: Experimental Column Set-Up
-------
Ion-Exchange Process 221
Results
Resin Selectivities
Thirty-two strong and weak-base resins were tested for
sulfate, nitrate, chloride and bicarbonate selectivities. These
selectivities were then related to the following resin properties:
matrix, functionality, porsity, capacity, pKa and type. Details of
those important relationships may be found in Reference 3. A
Significant new result was that the resin matrix was the most
influential factor in the determination of divalent/ monovalent
selectivities. It is hypothesized that if two charged ion-exchange
sites are within a guaranteed close distance then the resin is very
divalent ion selective. That condition can be satisfied first by
choosing the proper resin polymer structure (matrix) and sec-
ond by selecting the proper functionality (e.g., primary, secon-
dary, tertiary or quaternary amine).
Sulfate was always preferred over nitrate by all the strong and
weak-base resins tested which exhibited an extremely wide
range of selectivities: «n= 1.71 to 137. It is expected that the
sulfate preference will hold true for any resin tested with feed
waters having total dissolved solids concentrations up to at least
3000 ppm (0.06 N as CaCoj). Example isotherms for moderately
(Figure 4) strongly (Figure 5) and very strongly (Figure 6)
sulfate selective resins are given for comparison purposes.
Nitrate was always preferred over chloride by all the anion
resins tested although the range of preferences was relatively
narrow:aci= 1.85 - 4.33 and, as expected, was independent of
total solution concentration. The chloride/nitrate isotherms
(lower curves in Figures 4 6) demonstrate a weak nitrate
preference (Figure 6) and moderate nitrate preferences (Figures
4& 5).
Bicarbonate and carbonic acid are not significantly taken up
by ion-exchange resins in binary equilibrium with HNO,. The
expected selectively sequence has been verified as sulfate >
nitrate :> chloride»bicarbonate. Table I summarizes the
selectivity characteristics of all the anion resins studied during
the course of this research. When using the selectivities listed in
the table, note that the sulfate/ nitrate selectivities are strictly
valid only at 0.005 N (250 ppm as CaC03) while the chloride/ ni-
trate values are independent of total concentration.
Multicomponent Effluent Profiles
The effluent concentration vs bed volumes of effluent curves
for all eleven runs are typified by Figure 8, a two-bed run, and
Figure 9, the single-bed run. Consider Figure 8 (Run 11) as
typical of the general effluent behavior of the four anions of
interest and note that, as predicted from multicomponent
chromatography theory, there are four plateaus each
corresponding to one of the anions, and that these plateaus are
separated by rather abrupt transition zones. The first compo-
nent to appear is always H2C03 or HCOrfollowed by C1-, N07,
and finally SOJ, the most preferred species. Observe also that, as
expected, all species save for the most preferred SOf appear at
some time in the effluent in concentrations from 20-300% higher
than in the feed water. An abrupt increase in the concentration
of one component is always accompanied by a correspondingly
abrupt concentration decrease in a second component once the
H2COj has been eluted. The single-bed effluent profile (Run 7,
Figure 9) differs from the two-bed profile (Figure 8) in that the
strong-base anion bed was presaturated with C1-, the exchang-
ing ion, which was always present in the effluent.
Examine the chloride and nitrate breakthrough curves from
the two-bed run in Figure 8 and note that by not terminating the
run on conductivity breakthrough (CI- breakthrough) the
capacity of the bed (and length of the run) is increased from 320
to 480 bed volumes (Vc). This is a 50% efficiency increase and is
Max =5.13
^.00
100.00
200.00
800.00
400.00 '500.00 600.00
BED VOLUMES OF EFFLUENT
700.00
800.00
900.00
tooo.oo
Figure 8: Run No. 11, Effluent Concentration Profile
-------
222 Ion-Exchange Process
due to elution of species less preferred than nitrate. In Figure 8
and 9, C„'s indicate the influent concentrations/of each of the
anions; see Table III for the complete test water composition.
Table III: Ca-Mg-Fe Test Water for Two-Bed Neutral Elution
Runs Test Water 3 (Runs 9-11)
x.
Ion
Meq/1
ppm
1
.54
.27
.18
Nil
Ca++
Mg++
Na+
Fe++
3.0
1.5
1.0
Nil
60
18
23
1
.27
so4=
1.5
72
.27
NO ^
1.5
93
to
CI"
1.5
53.2
.18
Cations
HCO ~
o
1—1
61
3
& Anions
5.5
381
o
li
c
u
0055 N
Hardness = 225 ppm
as CaCO^
no3-n =
21 ppm, XN0^ -0.27
Maximum Possible Chemical Efficiency
Maximum possihlc chemical efficiency (Fm) is defined simply
asy\ the average equivalent fraction ol nitrate on the resin atthe
end of the run. Since yN varies with distance into the bed, the
weighted average value yN, must be used to represent the ratio of
nitrate removed to all ions removed. In the ideally efficient
process this would of course approach 1.0 which would only be
possible if nitrate were much preferred over all other anions
which it was not in these ex periments.
em = yN =
Vn
meq N03on resin at end of run
Total meq of ions on resin at end of run
meq N03 in — meq NQ3 out
Initial meq of all ions + meq of all ion's in
- meq of all ions out
Overall Chemical Efficiency
Overall chemical efficiency (F,,) is product of the maximum
possible chemical efficiency (EM) and the observed regeneration
efficiency (EK).
Eo = emer
Ej^ = Regeneration Efficiency =
meq total capacity of anion bed
meq anion regenerant applied
Eq = Overall Chemical Efficiency =
meq N03 removed
meq anion regenerant applied
Figure 9: Run No. 7, Effluent Concentration Profile
300
BEO VOLUMES OF EFFLUENT
-------
Ion-Exchange Process 223
Selectivity Effects on Column Performance
Nitrate/Chloride selectivity (afl) is the most important
selectivity determining the relative amount of nitrate on the
resin at nitrate breakthrough, i.e., in determining the maximum
possible chemical efficiency (EM = yN). This is both good and
bad: good because all the resins were nitrate selective wrt
chloride, bad because little variation existed in the values ofa(^
among the thirty-two resins tested («c, = 1 -85 -4.33) and no real
significant effects on selectivity seem possible by further varying
the important independent variables matrix and relative
degree of crosslinking.
Sulfate I nitrate selectivity (Ǥ) is nearly irrelevant in deter-
mining the average equivalent fraction of nitrate on the resin at
the end of a run (yN). Surprisingly, slight increases in yN are
possible as a result of increasing rather than decreasing the
sulfate selectivity ¦«§. The simple explanation offered for this is
about (I) all the sulfate will be removed from the feedwater
regardless of its actual selectivity because it is the most preferred
species and (2) high sulfate selectivity promotes a short sulfate-
rich zone near the column entrance in which almost no nitrate is
removed thereby leaving essentially all of that species to
compete with the lesser preferred chloride in the second
equilibrium zone of the column which is where nearly all of the
nitrate is concentrated; see Figure 3.
Regardless of the explanation, the effect of the selectivity of
the most preferred species, sulfate, is predictably slight when the
objective is to remove nitrate, invariably the lesser-preferred
species. That is graphically demonstrated in figure 10 where the
sulfate/ nitrate selectivity varies from 2.83 to 94 with no effect on
the maximum possible chemical efficiency or on the
throughput -a normalized measure of the equivalents of ions
fed to the bed per equivalent of bed capacity.
The Effect of Feedwater Nitrate Concentration and Flow
Rate
The most important influence on yN is, predictably, xN the
equivalent fraction of nitrate in the feed water; when it's low,
process efficiency will be correspondingly low because the
exhausted resin will comprise mostly sulfate and chlorides-
species not intended to be removed. In these studies the
influence of xN, at 2.5 gal/min ft3, atl= 3.9 and xs = 0.3 was as
follows:
Equivalent Fraction
of Nitrate in Feed
Water
XN
.20
.27
Average Equivalent
Fraction of Nitrate
on spent Resin
^n
.32
.40
Relative
Efficiency
y~N^xN
1.70
1.48
Relative efficiency has been included to illustrate that yw is not
simply linearly related to xN. In addition to «cj and xN the
iterrelated variables, exhaustion rate, bed depth and superficial
detention time (r), are quite significant. Short detention times
(r<3.0 min), shallow beds (depth<;60 cm) and high exhaustion
rates (>2.5 gal/ min ft') reduce yN by causing relatively more
chloride, apparently the kinetically favored anion, to be in the
O = COLUMN RUN 5
A - COLUMN RUN 6
a® = 2.83, yN = 0.41
f i- ¦— '
.00
m yi it* i
0.50
1.00
THROUGHPUT
Figure
1.50 2.00 2.50 3.00
T - THROUGHPUT - EQUIVALENTS SOLUTION / EQUIVALENTS EXCHANGER
10: Column Effluent Profiles (Nitrate) Effect of Sulfate Selectivity on Column Efficiency
3.50
-------
224 Ion-Exchange Process
resin at nitrate breakthrough. That is summarized below for the
condition where xN = .27, xs = .27, Xa = .27 anda^j = 3.9:
Exhaustion
Rate
gal/min ft3
2.44
4.88
Detention
time
r min
3.1
1.5
Resin
Depth y
cm n
61
31
.41
.39
Although xs was not a variable in the column experiments it
will greatly influence yN because all the sulfate fed to the column
is still on it at nitrate breakthrough. When xs is high, the
efficiency, yN, will be low.
The Effect of Regeneration Stoichiometry on Efficiency
Regeneration level influences both the overall chemical
efficiency (Eo) and the maximum possible chemical efficiency
(Em). For the two-bed system the regeneration level has been
defined based on the final anion column capacity. In practice,
the total equivalent capacity (TEC) of the cation bed must equal
or exceed the final anion bed capacity. It has been determined
here that a downflow regeneration level of 300% of the theo-
retical HC1 required must be applied to the cation bed if calcium
and magnesium are the primary cations on the resin. Levels
much lower than that cause premature cation breakthrough,
increasing pH and reduced anion bed capacity with smaller
values of yN at breakthrough. High regeneration levels on the
- "nanrentablv low effluent pH
lUVIVUuiti^, I
values of yN at breakthrough. High regeneration _
other hand maximize yN but cause unacceptably low effluent pH
forcing termination of the run.
For the single-bed strong-base anion process regenerated with
NaCl it is expected that regeneration levels of 300% or greater
will be required for efficient regeneration. This is based on
published rather than experimentally determined information1.
The overall chemical efficiency (Eo) can be expected to be
about 13.3% for both the single-bed and two-bed processes. This
is based on the observed average equivalent fraction of nitrate
on the resin at the end of the runs (5^) with a feedwater
containing the same equivalent concentration of nitrate, chlo-
ride and sulfate and an irrelevant amount of bicarbonate which
undergoes no net removal in either process.
A comparative process economic evaluation reveals that the
two-bed process with NH, and HC1 as regenerants has chemical
plus disposal costs which are approximately 50% higher than the
single-bed process assuming an overall chemical efficiency of
13.3%, 25% bypass water, a feedwater with the composition of
Test Water 3 (Table III), NaCl-NaN03 brine disposal by
trucking 8 miles before discharging into a stream, and no
disposal cost for the high-nitrogen content wastewaters from the
two-bed process which are given away for their fertilizer value.
Considering only the costs for regenerants, the two-bed process
costs three times as much to operate as the single bed process but
yields nitrate-free, partially softened water and a land dispos-
able regenerant with fertilizer value. See Table IV.
Nitric acid is definitely not recommended as a regenerant in
the two-bed process even though it would greatly enhance the
fertilizer value of the regenerant wastewaters. It is too costly,
46.5 «/1000 gal treated water (12.3 e/m3), requires excess cation
bed rinsing to reduce nitrate and allows the possibility of
disastrous nitrate and acid pollution of the water supply in the
event of an operating error. Even though HC1 is more costly
than H,S04 it may be more economical where large excesses of
H2S04 are required due to CaS04 fouling of the cation bed.
SUMMARY
Regarding the general applicability of these experimental
results to industrial processes, our conclusions can be inter-
preted to demonstrate the importance of the following consid-
(1) The preferences which commercially available anion
exchangers exhibit for the common anions varies drastically
especially in dilute multicomponent solutions with ions of dif-
fering valences. Nevertheless, these drastic differences do not
translate simply into good or bad column performance.
(2) Ion-exchange system operating costs can often be reduced
greatly by operating the bed to breakthrough of the ion intended
to be removed rather than operating to the ion exchange
capacity of the bed.
(3) Although predictably more costly, practical systems can
be designed which yield useful land-disposable regenerants. The
resumption is that industrial ion-exchange processes with
recyclable or legally disposable regenerants can be designed if
the regenerant disposability is a primary design consideration.
(4) The usual method of downflow exhaustion with downflow
regeneration typically results in the need for 300 + % excess of
regenerants. The need for excess regenerants become greater
whenever ions highly preferred by the ion exchanger (e.g., SOj
and Ca++) are involved. Although not specifically investigated
in this research, coutercurrent(upflow) regeneration can minim-
ize the inefficient regeneration problem with its high costs for
regenerant chemicals and their ultimate disposal.
(5) Kinetic considerations are important when eluting the
ions not intended for removal. High service flow rates can result
in premature breakthrough of the ion intended to be removed
and in a resin loading favoring the faster ions not intended for
removal.
REFERENCES
1. Beulow, R. W„ K. L. Kropp, J. Withered, and J. vj.
Syomons, "Nitrate Removal by Anion Exchange Resins,"
Water Supply Research Laboratory, National Environ-
mental Research Center, U.S. EPA, Cincinnati, Ohio,
May, 1974.
2. Bingham, E. C„ "Fertilizer Maker Stops Nitrogen," Water
and Wastes Engineering, P.E 4, November, 1972.
3. Clifford, Dennis A., "Nitrate Removal from Water Supp-
lies by Ion Exchange: Resin Selectivity and Multicompo-
nent Chromatographic Column Behavior of Sulfate,
Nitrate, Chloride and Bicarbonate," Ph.D. Thesis, Univer-
sity of Michigan, University Microfilms, Ann Arbor,
Michigan, Pub. No. 77-7893.
4. Diamond Shamrock Chemical Co., Duolite Ion-Exchange
Manual, Redwood City, CA, 1969.
5. Dorfner, K., Ion Exchangers: Properties and Applications,
3rd Ed., Ann Arbor Science, Ann Arbor, Mich., (1972).
6. Evans, S., "Nitrate Removal by Ion-Exchange," J. WPcf,
V. 45, No. 4, pp. 632-36, April, 1973.
7. Gauntlett, R. B., "Nitrate Removal from Water by Ion-
Exchange," Water Treatment and Examination, V. 24, p.
172,(1975).
8. Gregg, J. C.,"Nitrate Removed at Water Treatment Plant,*'
Civil Engineering—ASCE, p. 45, April (1973).
9. Helfferich, Friedrich, Ion-Exchange, McGraw-Hill Book
Co. Inc., New York, N.Y., 1962.
10. Helfferich, F. G„ "Multicomponent Ion Exchange in Fixed
Beds," / & EC Fund., V. 6, No. 3, p. 362, (1967).
11. Helfferich, F. and G. Klein, Multicomponent Chromato-
graphy: Theory of Interference, Marcel Dekker, New York,
1970.
-------
Ion-Exchange Process 225
12. Holzmacher, R. G., "Nitrate Removal from a Ground
Water Supply," Water and Sewage Works, p. 210, July
1971.
13. Klein, G., D. Tondeur, T. Vermeulen, "Multicomponent
Ion Exchange in Fixed Beds," / & EC Fund., Vol. 6, No. 3,
p. 339 (1967).
14. Midkiff, W. S., and Weber, W. J., Jr., "Operating Charac-
teristics of Strong-Base Anion Exchange Reactors," Pro-
ceedings of the 25th Purdue Industrial Waste Conference,
May, 1970.
15. Tondeur, D., and G. Klein, "Multicomponent Ion-
Exchange in Fixed Beds," I & EC Fund., V. 6, No. 3, p. 351,
August (1967).
16. U.S. EPA, "Interim Primary Drinking Water Standards,"
Federal Register, December 24, 1975.
Table IV: Economic and Regenerant Wastewater Comparisons Between the Single-Bed and Two-Bed Processes
Item
Single-Bed
Process
Two-Bed
Process
Regenerant Chemical Costs, C/1000 gal I^O Supplied. . .
12 .2
37.1
3
Regenerant Chemical Costs, C/m H20 Supplied
3.22
9.72
Regenerant Disposal Costs C/1000 gal Supplied . . .
12.2
Nil
3
Regenerant Disposal Costs <=/m H20 Supplied
3.22
Nil
Regenerant plus Disposal Costs C/1000 gal 1^0
24 .4
37 .1
Regenerant plus Disposal Costs
-------
Solid-Liquid Wastes from Coal
Conversion Processes and
Control Technology*
Subhash S. Patel and V. Bruce May
Hittman Associates, Inc.
Columbia, Maryland
INTRODUCTION
The current emphasis to utilize coal has as its primary
emphasis the removal of polluting and hazardous constituents
to produce clean gaseous, liquid, and solid fuels. Unfortunately,
once removed from the coal, these same constituents appear in
the by-product and waste streams generated during processing.
Of particular concern are those waste streams which ultimately
must be returned to the environment either by discharge to the
atmosphere, by discharge to surface or groundwaters, or by
surface or subsurface disposal as solids.
Environmental factors will influence numerous aspects of
coal conversion plant design and operation. In the planning and
design stages potential sources of pollution will require
identification. Site selection will be influenced by physical
factors such as availability of water, suitable disposal areas for
solid wastes, and existing and planned discharge limits. Plant
operating practices will be required to conform to the standards
in effect when production begins and during the plant life.
Many variations in processing systems are found in the devel-
oping coal conversion technologies. Although each conversion
scheme utilizes a different approach, the environmental aspects
are quite similar: based upon the conceptual design using pilot
plant data, a full-scale commercial plant may generate between
0.5 and 1.5 million gallons of highly-contaminated wastewater,
and solid wastes will amount to approximately 2500 tons per
day. This wastewater may contain more than 1000 ppm each of
COD, ammonia and phenols, appreciable levels of cyanide and
thiocyanate, and low levels of trace elements, inorganic and
organic compounds. Ash accounts for the largest amount of
solid waste and the major concern is its disposal and possible
leaching of trace elements.
A comprehensive multimedia environmental assessment,
which will lead to selection of best control and treatment
methods can significantly reduce the impact of coal conversion
technology on the environment. To provide a preliminary
assessment common and exceptional operational and process
modules between coal gasification and liquefaction have been
compared with respect to their operating conditions and solid-
liquid waste discharges. The term module is used here for unit
operations or unit processes employed by a process. The
modular sources of wastewaters from the coal conversion
facility have been identified and a qualitative comparison of
these discharge streams in terms of their characteristics is per-
* This paper is based in part on studies conducted for the U.S.
Environmental Protection Agency under Contract No. 68-02-
2162, "Environmental Assessment of Effluents from Coal
Liquefaction and its Utilization."
formed. Based on theexisting literature information wastewater
characteristics from Coke production, Synthane, and Solvent
Refined Coal (SRC) processes have been listed. Wastewater
treatment methods and their efficiency of removal have been
evaluated. Modular sources of solid waste have been identified,
the waste characterized in terms of trace elements, and common
disposal methods are described.
Common Modules
Coal gasification and coal liquefaction processes employ a
number of common modules. Figure 1 shows major modules
that have been identified as being part of both high-Btu
Table I: Modular Comparison Between Coal Gasification and
Coal Liquefaction
Co«l Preparation
Reactor System
Quenching
• Includes crushing, sizing
grinding and drying.
• Size range: fixed beds - ?"
to 1/4", fluid beds-4 to
100 mesh and entrained beds-
50 to 325 mesh.
e Coal dried to less than two
percent moisture for most
processes.
• Most processes have a mech-
anical feed system (lock
hoppers or screw feeder). Few
employ coal-o1l or coal-wtter
slurry feed system.
e Caking coals are preheated
to destroy caking properties
for some processes.
« Two phase (snlld-gas) reactor
system Include moving, fluid-
Ized entrained and molten beds.
e The reactor bed 1i non-
catalytic.
e High temperatures
(1100* to 3600*F) and low
pressures (IS to 1500 ps1)
Involved.
e One of the primary process
steps employed by all pro-
cesses that produce signi-
ficant amounts of tar,
ammonia and phenol.
• Water end oil used as
quenching medium.
e Employed by most of the
Mgh-ltu processes as one of
the primary steps to adjust
the H./C0 ration with the
exception of 'vw. Not re-
quired for <•' 1 of the low-
Btu process
..LIQUEFACTION
• Includes crushing, sizing,
qrlndinq and drytnq.
e 5'1z# range: donor solvent
and hydroqenttion proces-
ses-lets than 100 mesh,
pyrolysis processes -
less 2QQ «es*v (some
variation of the above
values e«>st)
• Coal dried to less than
two percent moisture
for most processes.
e AH hydrogenation and
donor solvent processes
have coal-oil slurry
feed system. Pyrolysis
and liquefaction via
synthesis qas employ
mechanical feed system.
t Coal-oi1 slurry 1s
preheated to maintain
the reaction temperature.
e Three phase (sol Id- Hqut4>
gas) system Include fluid*
zed, packed, and embulllent
beds.
e The reactor bed may be
catalytic or non-
catalytic
t Low temperatures
(700 to 1HQ°F) end
high pressures (BOO to
4000 psi) involved.
e Pyrolysls and lique-
faction via synthesis
gas generation process
use this module as one
of the primary modules,
other processes utilize
1t as a secondary step
for hydrogen generation
only.
• Water and oil used as
quenching medium.
e Employed as one of the
primary steps by Hque*
faction via synthesis
gas generation processes.
Hydrogen generation for
other processes uses it i
as * secondary step. I
226
-------
Solid-Liquid Wastes 227
Figure 1: Comparison of Coal Gasification and Liquefaction
Modules
-------
228 Solid-Liquid Wastes
Table I: Modular Comparison Between Coal Gasification and
Coal Liquefaction (Continued)
1
RATIFICATION
1 l(JUFF ACT [ON
e feed includes secondary
stream* from hydrogen
generation and gas
separation.
Acid Gas Removal
• Feed 1s the primary stream
from gasifier.
• Elemental sulfur is recovered
and tail gas cleanup may be
necessary.
• Elemental sulf"r
recovered and tail gas
cleanup may be
necessary.
Methanation
• Gasification for low and
medium Btu gas do not employ
this step.
• Not required.
Gas Separation
• Essential for upgrading the
product gav to h*gt\ Btu qas
• Not required.
» All hydrogenation and
donor solvent processes
separate the gas from
the reactor product
stream by pressure reduc-
11 on in two or three
stages
Solids-Liquid
Separation
• Not required. (Solid par-
ticulate separated frow
gas by cyclones, scrubbers
or electrostatic precipita-
tor)
• Most processes with the
e«cept1on of liquefaction
v^a synthesis gas genera-
tion use one of the
methods; filtration,
centrifug^ng, hydro-
cyclonmg, flash or
vacuum distillation and
solvent deashing.
Hydrotreatment
• Mot required.
• Catalytic process
employ to upgrade the
raw 1 iquid fuel by
removing S, N, and 0.
Fractionation
• Not required.
• Required for solvent
recovery and obtaining
separate fractions of
the product fuel o11¦
Hydrogen Generation
• Essential for hydrogasi-
fication only.
• Essential for all lique-
faction processes
except 1iquefactIon via
synthesis gas generation
processes.
Auk 11lary Facilities
• Hydrogen generated by
gasification of char
through steam and oxygen
or air.
• Includes: o*ygen and
power generation, raw and
wastewater ticataient,
product arid -.[product
handling f.d Itorage, and
cooling towers.
• Hydrogen generated by
gasification of char or
coal through steam and
oxygen or i1r
« Includes oxygen and power
generation, raw and
wastewater treatment,
product and byproduct
handling and storage,
and cooling towers.
gasification and liquefaction processes which use direct
hydrogenation. The liquefaction processes consist of essentially
all the modules utilized in gasification processes except those for
methanation quenching, and shifting. However, liquefaction
processes have some exceptional modules—not present in
gasification, such as solids-liquid separation, hydrotreating, and
fractionation. A brief comparison of different modules identi-
fied in coal gasification and liquefaction is summarized in Table
I.
Coal preparation includes operations similar to those used in
power plants, for example: crushing, sizing, grinding and
drying. Comparing the size requirements, coal gasification
processes in general encompass a broader size range of coal feed
than coal liquefaction processes. Gasifier feed coals are sized as
follows: for fixed bed 2" to for fluid beds 4 to 100 mesh,and
for entrained beds 50 to 325 mesh. Liquefaction reactor feed
coals are sized to about less than 100 mesh for most of the
processes. Drying reduces the coal moisture content to about
two percent or less for most conversion processes. Pretreating of
the coal feed to some gasifiers is necessary to destroy caking
properties. Most gasifiers have a mechanical feed system. A few
use oil-coal or water-coal feed slurry systems. Most liquefaction
processes use an oil-coal slurry feed system. Exceptions are
processes which use mechanical feed systems.
Reactor systems in coal conversion processes can have
various configurations. Coal gasification reactors are more
varied in type than those used in coal liquefaction. Moving,
'tirred, rotating, fluid, entrained, and molten bath reactors are
ed for coal gasification. Liquefaction processes use either
.eked, fluid, stirred, molten bath, or ebullated bed reactors.
Gas cooling and quenching is necessary to remove coal dust,
tars, heavy oils, and phenols formed in the gasifier. Tars and
heavy oils are removed by cooling. A direct water wash removes
ammonia, light oils, phenols, and dust. Pyrolysis and indirect
liquefaction processes generate a gaseous product stream.
Cooling and quenching thus is essential. Hydrogen generation,
essential for all liquefaction processes, gasifies char and/ or coal
to produce hydrogen rich synthesis gas. Shifting is necessary to
adjust the H i/CO ratio. In gasification and indirect liquefaction
this is one of the primary steps as opposed to liquefaction by
direct hydrogenation or extraction where it is used for hydrogen
generation only.
Gas cleanup and by-product recovery modules are essential
pollution control equipment in both coal gasification and
liquefaction. The objectives of this operation is to remove acid
gases (H2S, C02, S02, NOx, HC1, HCN) and to recover byprod-
ucts such as sulfur, phenol, and ammonia. Feed to the acid gas
removal module for coal gasification comes from the shift
conversion module. Acid gases are separated from the major
process stream, which contains CO, H2 and CH4—these
components are required to generate pipeline quality gas. In
coal liquefaction, the feed stream to this unit is not a major
process stream. It originates at the gas separation module. Some
other side streams that may be generated from the processing of
major solid-liquid streams further down stream in the process
will be added to this feed stream. Gaseous streams from char
and /or coal gasification for hydrogen generation, after quench-
ing and shifting, are fed to this module. After removal of acid
gases the gas stream will consist mainly of synthesis gas and will
be used for hydrogenation.
Modular Exceptions
There are very few modules which are not employed by either
coal gasification of coal liquefaction. Generation of low- and
medium-Btu gas does not require the methanation module.
However, methanation is essential for producing high-Btugas.
The solid-liquid separation module (not present in coal
gasification) is an essential part of the process for coal liquefac-
tion. Filters, hydrocyclones and centrifuges are as mechanical
modes of seapration. Solvent deashing involves the addition of a
solvent to aid in precipitation of solids by increasing the particle
size and settling rates. Flash and vacuum distillation utilizes
partial pressures and high temperatures for this separation.
Hydrotreating and fractionation are two other modules
which are absent in coal gasification. Raw liquid fuel from the
solid-liquid separation module in pyrolysis and donor solvent
processes is upgraded by catalytic hydrotreating, to reduce the
nitrogen, sulfur, and oxygen content of the fuel oil. Fractiona-
tion of the fuel oil separates the liquid product into light, middle,
and heavy distillates.
Liquid Wastes
All modules of a coal conversion complex are potential
sources of liquid wastes. Coal preparation and auxiliary
facilities generate non-contact liquid wastes such as cooling
tower blowdown, and all other modules generate process liquid
wastes, the former being less polluted. Wastewater treatment
and control technology may be designed for maximum reuse of
the water. Water treatment and reuse systems for gasification
processes can approach low-discharge effluent levels. Because of
the potentially more contaminated wastes liquefaction plants
may have more rigorous treatment requirements, similar to
those needed in petroleum refineries. Waste streams originating
from various components have different physical, chemical, and
biological characteristics. Some may require simple inplant
control before reuse or final end-of-pipe control. The compo-
nent sources of liquid wastes and the abatement control
technology available for such wastes is discussed below.
-------
Solid-Liquid Wastes 229
Noncontact Liquid Wastes and Control
The major pollution problem from coal preparation and
handling is stormwater runoff. Coal storage piles have large
surface areas and rain water may react with coal to extract
organics. Dissolved and suspended solids are the major contam-
inants in runoff water. Control can be obtained by storage of
small quantities of coal in silos, and by treating large storage of
piles with a surface coating of polymer, oil, or asphalt.
Runoff from processing areas may contain oil, phenols, other
organics, and suspended solids. Careful housekeeping within
the coal conversion complex cap reduce the pollution potential
of water wastes. The runoff water is usually collected in a sepa-
rate retention pond, and can be used as makeup water for
cooling tower and boiler feed water after treating it for oil and
solids removal.
Cooling tower and boiler blowdown contain water soluble
compounds such as chlorides (perhaps as NH4C1) and thiocya-
nates and can be used as quench water for ash removal.
Alternatively, the blowdown can be evaporated in a pond to a
low volume highly concentrated waste stream, and then dis-
posed of.
Process Liquid Wastes
Process liquid wastes are process specific with respect to vol-
ume and characteristics. However, much similarity exists in
their origins and in control methods. High temperature coal
gasification processes generate less tars, phenols, and hydrocar-
bons than those operating at lower temperatures. Gaseous
outputs from lower temperature gasification, coal pyrolysis, and
some hydrogenation processes are water quenched. The gas
liquor stream generated contains tar, oils, phenols, free ammo-
nia, sulfur, and cyanide compounds. Coals with high oxygen
content produce more phenolics than others. Cyanides may be
converted to thiocyanates by sulfide in the quench water. Part of
the entrained solids in the gaseous stream from the reactor will
enter the gas liquor.
The water condensed after the shift reactor will be similar in
characteristics to gas quench liquor but more dilute. Water pro-
duced during methanation is high quality water and usually will
be suitable as boiler feed water without further treatment.
Condensates from the gas separations module in liquefaction
processes contain volatile pollutants such as ammonia, phenol,
sulfur compounds, and hydrocarbons, but are low in salt
concentrations. The condensates are collected by cooling the
gases flashed off during two or three stage pressure reduction.
Water from hydrotreating overhead streams in liquefaction
contains ammonia and sulfides as primary contaminants but
phenol also may be present. Condensate water from fractiona-
tion contains small amounts of sulfides, ammonia, oil, and
phenols.
A generalized qualitative representation of the wastewaters
generated from various modules is shown in Table II. Waste-
water characteristics from Synthane, Coke production and SRC
processes are given in Table III. These tables present some
preliminary information about wastewaters and theircharacter-
istics. The anticipated effluent concentrations (5) of major
organic constituents are: phenols—1000 to 10,000; aromatic
amines—100 to 1000; monoaromatic hydrocarbons—10 to 100;
thiophenes—1 to 10; and polycyclic hydrocarbons—0.1 to 1
ppm.
Process Wastewater Treatment
The complex characteristics of wastewater streams that may
come from coal conversion suggests a number of alternative
treatment schemes. The overall wastewater treatment facility
which will best perform the necessary job of cleaning up the
wastewater will depend upon the variation in characteristics of
individual wastewater streams in terms of volumes and concen-
trations.
Depending on the quality of the raw influent, not all wastewater
streams will need processing through all the stages of the
treatment sequence. The complete treatment system involves a
combination of some unit operations and / or unit processes as
categorized in the following manner3:
Intermediate
Flotation
Coagulation
Precipitation
Equalization
Primary
Oil I Water Separation
Clarification
Filtration
Phenol Extraction
Ammonia Stripping
pH Control
Secondary/ Tertiary
Activated Sludge
Trickling Filters
Cooling Towers
Waste Stabilization
Ponds
Aerated lagoons
Filtration
Carbon Adsorption
Chemical Oxidation
Table II: Generalized Qualitative Representation of Wastewater Characteristics from Coal Conversion Complex*
Suspended
Flow Solids Acidity Alkalinity pH
£2fi Phenol 211 Ia£ Ammonia Sulfide Chloride Cvanid>
Coal Preparation
and Storage
XX
XXX
X
0
X
X
X
X
X
X
0
X
X
Quench and
Gas Scrub
XX
X
0
XX
XX
XXX
XXX
XXX
XX
XX
XX
X
X
Methanation
XX
0
0
0
0
0
0
0
0
0
0
0
0
Gas Cleanup
X
0
X
0
X
0
X
0
0
0
0
X
X
Gas/Sol ids/
Liquid
Separitfan
X
X
0
XX
XX
XX
XX
XX
X
X
X
X
X
Hydrotreating
X
0
0
X
X
0
X
X
0
0
X
X
0
Product Re-
fining (Frac-
tionation)
X
0
0
X
X
0
0
X
X
0
0
X
X
Boller-CT
Blowdown l Drift
tosses
XXX
0
0
X
X
0
0
0
0
0
0
0
XX
KE¥: X - Low ( 50 ppm).
XX -
Moderate (50-1000 ppe). XXX
- High
( 1000 ppm), 0
- Unknown
•Variation 1n wastewater qualities 1s possible depending on
the coal characteristics.
X
0
X
X
0
0
0
-------
230 Solid-Liquid Wastes
Table III: Composition of Wastewaters Representative of C oal Conversion Process Waters
Pollutant
Coke Plant
Liquor (8)
(mg/1i ter)
Synthane Process
Wastewater (8)
(mg/1 iter)
SRC Process
Combined Waste-
Water Stream (10)
(mg/1i ter)
PH
8.3-9.1
7.9-9.3
6.9-9.0
COD
2500-10000
1700-43000
1000-9600
Ammoni a
1800-4300
2500-11000
N/A
Cyani de
10-37
0.1-0.6
N/A
Thi ocyanate
100-1500
21-200
N/A
Phenols
410-2400
200-6600
30-1500
S u1 fide
0-50
N/D
N/A
Alkalini tv
1200-2700
N/D
N/A
(as CaCOj)
Speci fi c
1 1 000-32000
N/D
N/A
Conductance
(as ymho/cm)
Figure 2 shows three possible alternatives that may constitute
an overall treatment plant. Many factors such as the quality of
wastewater, site location, climatic conditions, cost, and the
required pollutant reduction will determine the final treatment
scheme.
Low temperature gasification and pyrolysis based liquefac-
tion processes generate an oily quench liquor which can be
treated in the traditional API gravity separator. The tempera-
ture of the quench liquor, density and size of oil droplets, and
type of contaminated solids will depend on the operating
conditions of the reactor system. Removal efficiencies4 of 60-99
percent for oil and 10-50 percent for suspended solids have been
reported. The use of tilted plate separators can increase the
removal efficiency and reduce cost and space requirements.
Further reduction in the amount of contaminated oil and solids
may be necessary. Dissolved air flotation aided by addition of
alum or polyelectrolytes and followed by gravel filteration will
serve this purpose.
Coal conversion plants generating sufficiently large quantities
of phenols to justify recovery will utilize a phenol recovery
system. Commercial liquid extraction processes can be used.
One of these is the Phenosolvan process1 which uses isorpopyl
ether as the extracting agent. Lurgi, the process developer,
claims that phenol can be reduced to 5-20 ppm in water. Jones &
Laughlin Steel Corporation has developed a solvent extraction
process,6 now used in coke oven plants. A 99 percent phenol
recovery with only 1 to 4 ppm phenols in the dephenolized waste
is claimed for this process. In coal conversion processes
generating small quantities of phenols, and for wastewater
streams from shift reaction, separation, hydrotreating, and
fractionation, a phenol recovery stage may not be required. This
wastewater may be directed to the ammonia stripping stage. For
such streams the possible sequence of cleanup may be ammonia
stripping, oil/water separation, and solids removal, followed by
secondary/tertiary treatment methods.
Ammonia in wastewaters from different units, formed from
N/D = Not determined
N/A = Not available
Figure 2: Wastewater Treatment for Coal Conversion Facility
-------
Solid-Liquid Wastes 231
organic nitrogen compounds in coal, can be removed by air or
stream stripping4, More than 75 percent of the NH 3and 40 per-
cent of the remaining phenol present in the wastewater stream
can be removed by this technique, depending upon the design of
the stripper.
Wastewater streams may be either alkaline or acidic, and thus
may reduce the effectiveness of biological treatment processes.
pH adjustment of the combined wastewater stream that flows to
secondary treatment is required for healthy microorganism
growth. The wastewater flow rate may vary significantly with
time. Biological processes perform effectively when the flow and
quality of influent waste streams are kept fairly constant. This
can be accomplished by providinga holding pond with sufficient
residence time to even out process variations.
Wastewater streams with high phenol concentrations but
smaller amounts of other organic fatty acids and oils can be
biotreated in cooling towers. In actual operation these systems
have achieved 98+ percent phenol reduction. Operating experi-
ence with these systems have been reported to be good. Howev-
er, some waste sludge is removed via drift losses and inefficient
removal could result in high discharges of the contaminants to
the atmosphere.
Activated sludge and trickling filters are two other secondary
methods that may be employed as end-of-pipe treatment
methods. EPA reports4 removal efficiencies of 80-99 for BOD,
50-95 for COD, 60-85 percent for suspended solids, 80-90 for
oil, 95-99+ for phenol, 33-99 for ammonia, and 97-100 per-
cent for sulfides. Trickling filters are not as efficient as activated
sludge and EPA reports removal efficiencies of 60-85 for BOD,
30-70 for COD, 60-85 for suspended solids, and 50-80 percent
for oil.
The converted organic matter must be removed by sedimenta-
tion. Nutrient nitrogen and phosphorus are required for
biological growth. Nitrogen will be supplied by the presence of
ammonia in wastewater streams and phosphorus could be made
available by partly directing the boiler or cooling tower
blowdown to the bio-tank.
The effluent from the biotreating unit will be passed through
dual-media filters consisting of anthracite and sand to achieve a
very high quality effluent or recycle stream. Activated carbon
can be used in place of anthracite. The applicability of a sepa-
rate carbon-adsorption system is questionable due to the costs
involved in regeneration or replacement of the carbon. Chemi-
cal oxidation can be used for reduction of phenols and cyanides
in wastestreams by oxidants such as chlorine or ozone. The
presence of cyanides in some wastewater streams generated
during coal conversion processes may indicate ozone treatment
before combining this wastewater stream with others.
Solid Waste Disposal
Solid wastes from coal conversion processes include ash and
slag residues from gasifiers, spent catalysts from-ydrogenation,
hydrotreating, shift, methanation, and sulfur recovery units,
and sludge from raw and wastewater treatment plants.
The amount of ash, which accounts for the largest portion of
solid wastes, depends on the coal. Char produced from
liquefaction processes may be gasified to produce hydrogen
required by the process, and ash is left as the solid waste. The
major concerns about ash disposal are the presence of trace
elements and fugitive dust emissions. Table IV shows the trace
element analysis of ash from a Lurgi gasifier using Illinois #5
Seam coal and of mineral residue from the SRC process.
Ash from coal conversion processes may exit as bottom ash or
slag, and as fly ash from the gasifier. Slag is crushed, slurried
with water, and pumped to dewatering bins. The dewatered slag
then will be removed to the specified disposal area. Fly ash is
removed from the gaseous stream by quenching. The ash slurry
Table IV: Trace Element Composition
Ar. h from L u r q i ( 2 )
ppm
Mineral Residue
from SRC (7)
ppm
A n t i rony j
Arsonic '
iiory 1 ] i uv
CP roil' i un '
Coh.l 1 t
1. e (.! 1 on i un: I
219
3 38
0.1
7 . 4
77
lr.O
32
0.005
1 20
204
124
is concentrated, after pH adjustment, to about 50 percent solids.
The slurry is further filtered and the dewatered ash is removed to
a disposal area. Coal preparation at the mine mouth can reduce
the amount of ash generated at the coal conversion complex by
lowering the mineral matter content of the feed coal. Blowdown
water from boilers and cooling towers can be used for ash
slurrying and quenching. Overflow water from dewatering bins
is also recycled for ash slurrying. Overflow water from thicken-
ers and filtrate water is sent for Wastewater treatment.
Ash may be disposed of by landfilling or by return to the mine
for use in reclamation. To some extent metals may be leached by
ground water. Various types of earth and soils can absorb some
metals. Ash may be utilized as a road-base material and for
building-block manufacture, providing it meets structural and
chemical specifications.
Catalysts will have a life-time of about two to three years after
which they may be regenerated or disposed of. Major concern is
the accumulation of trace elements which could have an adverse
environmental impact. Sludge from the wastewater treatment
facility can be disposed of as offsite landfill. The volume of
solids or sludge will increase as treatment requirements become
more stringent.
Research Needs
A comprehensive environmental assessment of coal conver-
sion facilities will require a quantitative environmental charac-
teristic determination of each effluent stream in terms of its
effect on alternate control or treatment methods. Detailed anal-
ysis of the effluents from some coal conversion pilot plants are
underway for this purpose. Increasing efforts in analytical
testing are necessary to select and develop a better control
technology. Limited information is available on the fate of trace
elements. Correlations between their behavior and operating
conditions of the process need to be developed.
Another area of interest, the health hazards associated with
solid-liquid, wastes can be studied by acute toxicity tests. Tars
heavy oils produced from low temperature gasification and
some liquefaction processes may contain potential carcinogenic
compounds. Characterization of these components and devel-
opment of methods of treating materials contaminated by their
release will be required to assure acceptable environmental and
health risks.
Better wastewater treatment methods that may be developed
will result in higher removal efficiencies of organic compounds
such as aromatic amines and polycyclic hydrocarbons. Research
-------
232 Solid-Liquid Wastes
work is also required on solid waste characteristics and their
leaching properties 10 develop better disposal methods.
REFERENCES
1. "An Investigation of Pollution Control Requirements for
Coal Gasification Plants," U.S. Environmental Protection
Agency, RTP, North Carolina.
2. Beckner, J. L., "Consider Ash Disposal," Hydrocarbon
Processing, February, 1976.
3. Cranes, B. A., Ford, D. L., and Brady, S., "Treatment of
Refinery Wastewaters for Reuse," National Conference on
Complete Water Reuse, Washington, D.C., April, 1973.
4. "Development Document for Proposed Effluent Limita-
tions Guidelines and New Source Performance Standards
for Petroleum Refining," p. 110, Environmental Protection
Agency, Washington, D.C., December, 1973.
5. Herbes, S. E., Southworth, G. R., and Gehrs, C. W.,
"Organic Contaminants in Aqueous Coal Conversion
Effluents: Environmental Consequences and Research
Priorities," Oak Ridge National Laboratory, Oak Ridge,
Tennessee.
6. Lauer, F. C., l.ittlewood, E. J., Butler, J. J., "Solvent
Extraction Process for Phenols Recovery from Coke Plant
Aqueous Waste," Eastern States Blast Furnace Coke
Association Meeting, Pittsburgh, Pa., February, 1969.
7. Petersen, M. R., Fruchter, J. S., and Laul, J. C., "Charac-
terization of Substances in Products, Effluents and Wastes
from Synthetic Fuel Production Tests," Battelle Pacific
Northwest Laboratories, Quarterly Report under ERDA
Contract No. EY-76-C-06-1830, September, 1976.
8. Rubin, E. C., and McMichacl, F. C., "Impact of Regula-
tions on Coal Conversion Plants," Environmental Science
& Technology, Vol. 9, No. 2, February, 1975.
9. Sather, N. F., et al„ "Potential Trace Element Emissions
from the Gasification of Illinois Coal," Illinois Institute for
Environmental Quality, Doc. No. 75-08, Proj. No. 80-206,
February, 1975.
10. "The SRC-1I Process," Gulf Mineral Resources Co.,
Denver, Colorado, October, 1976.
-------
Treatment of Solid
Residues from
Coal Gasification
Charles E. McKnight
Edgewood Arsenal
Edgewood, Maryland
INTRODUCTION
Energy predictions from various sources indicate a shortfall.
Attention has, therefore, become focused on the use of coal as a
partial solution, with subsequent realization that numerous
aspects of coal utilization need to be studied. Among these
aspects is the production of gas from coal. In such a study, re-
strictions on degrading the environment have a direct bearing on
discharge of water from the plants, this largely by virtue of the
solids content of the water. Increasing tightness of environ-
mental restrictions leads to a probable requirement for zero
discharge of liquid effluents. A suggested method of achieving
this is examined in this paper.
Coal Gasification
Coal gasification is a fuel-to-fuel conversion. It is needed to
produce methane to replace dwindling supplies of natural gas
that is now used as pipeline gas in the nation's pipeline network.
Once commercialized, it can continue in this role until coal
supplies diminish or become unavailable because of being used
to replace, for example, feedstocks to the petrochemical
industry.
As supplies of low-sulfur coal diminish, coal gasification must
operate on high-sulfur coal. To maintain the integrity of the en-
vironment, and at the same time to be more efficient energy-
wise, is the challenge of coal gasification.
Gasification proper can be described roughly as being (1)
pyrolysis (i.e., heating the coal in a reducing, non-oxidizing at-
mosphere), (2) pyrolysis with addition of steam and oxygen, or
(3) either of these followed by the addition of hydrogen. The first
will produce methane in small amounts, with larger amounts of
coal liquids; the second will produce carbon monoxide in
addition, which can constitute fuel gas; the third can produce a
variety of improved coal liquids1-2-3 such as naphtha. From the
second and third types, the water-gas shift reaction and
methanation can produce the desired methane-rich gas stream.
The latter two types of process are the kinds whose solid residue
waste disposal will be discussed in this paper.
Figure 1 shows a generalized process without hydrotreating.
Lump coal is introduced into the top of the gasifier. A water-
quench-and-scrub cleans the gas of particulates, tar, and liquids,
at which point it has too little heat content for pipeline gas but
can be methanated if first water-gas shifted to increase the
hydrogen content at the expense of the carbon monoxide.
Carbon dioxide, hydrogen sulfide, ammonia dust, and condens-
ibles are present; they must be removed before methanating, in a
step known as acid gas removal. Methane is then formed from
the hydrogen and carbon monoxide catalytically, forming also
water which is condensed out and re-used. Compression to
pipeline pressure, followed by a dehydration, produces the final
pipeline gas. The slag or ash is cooled by quench water.
The condensates from gas cooling and scrubbing lead to coal
oils and naphthas as well as phenols, ammonia, and aqueous
wastes.4 The wastewater is treated and re-used to the extent
possible as cooling or process water. The removed acid gases
(carbon dioxide and hydrogen sulfide) result in vented carbon
dioxide and a sulfur product such as elemental sulfur, sodium
sulfate, or sulfuric acid—products that can be kept out of the en-
vironment. In addition, there is a certain amount of dust and silt
from handling the coal during crushing, sizing, and conveying.
Solid Residues and Treatment for Disposal
Table 1 is a list of effluents that involve actual or potential
solid residues: Slag or ash is a solid after cooling. Sludge from
raw water treatment results in a solid or slurry. Sludge from a
sanitary waste is a solid, a source of compost or methane. Spent
adsorption carbon generates an ash or fines during regenera-
tion.
Sludge in the coal tar from gas washing and quenching may be
char, catalysts, alkali salts, fly ash, etc., in viscous high-melting
tar.
Leachate or drainage from slag (cooling system and coal
mineral constituents) may become a solid if zero liquid dis-
charge is desired. Cooling tower blowdown with dissolved solids
may be used to quench the slag.
Rock oversize, pyrites, etc., from coal breakers, screens,and
washers may be present if the project uses run-of-mine coal or
includes operation of a mine.
Construction wastes are numerous and varied—excess fill,
tires, grease, wallboard, pipe, steel, siltation, etc.
Sulfur dioxide scrubber residues from coal pretreatment and
from the power plant may end as solids such as calcium or
magnesium sulfates.
Ion exchange regenerants (blowdown), cooling tower blow-
down, and boiler blowdown may become solid residues when
zero liquid discharge is desired.
Sanitary effluent (not sludge) contains potential solid residues
and may be conveniently combined with other wastewater.
Gas purification and by-product purification result in waste-
water from acid gas collection, phenols recovery, ammonia
recovery, and washdowns. This wastewater may contain dis-
solved solids.
Water used for quench-cooling of slag may contain dissolved
solids in addition to slag.
Siltation is associated with mine drainage, coal-pile runoff,
and construction activities.
For waste treatment these wastes may be collected and
-------
234 Coal Gasification
QUENCH
SHIFT
COOL,
SCRUB
H2S REDUCTION
(CLAUS)
S02 REDUCTION
(STRETFORD)
-*4*-
-*+*-
RAW
MATERIALS
GAS FORMATION
CLEAN-UP
Figure 1: Coal Gasification for Manufacture of Pipeline Gas
Table I: Solid-Bearing Effluents/Discharges
PIPELINE
GAS
SULFUR
OIL
EFFLUENT
WINDAGE.
LOSSES,
BLOWDOWN
SLAG/ASH
SLUDGE
NITROGEN
REFUSE
PRODUCTS
1. SLAG FRIT (GRANULATED
COAL ASH. WATER. SALTS)
2. SLUDGE FROM RAW WATER TREAT.
CALCIUM & MAGNESIUM CARBONATES
& SUSPENDED RAW WATER SOLIDS
3. SLUDGE FROM SANITARY WASTE
4. SPENT CARBON W/ORGANIC TOXICS
5. SLUDGE FROM COAL TAR
(CHAR FINES, CATALYST DUST)
6. SEDIMENT IN STREAMS
7. SLAG LEACHATE (COOLING
SYSTEM SALTS, ORGANICS)
8. ROCK OVERSIZE FROM COAL BREAKER
9. CONSTRUCTION WASTES - EXCESS FILL
10, S02 SCRUBBER CONDENSED RESIDUE
11. ION-EXCHANGE REGENERANTS FROM
PREPARING BOILER FEED WATER
Na CI Mg Ca A04 N03 OTHER RIVER SALTS
12. COOLING TOWER BLOWDOWN
(CONCENTRATE OF DISSOLVED SALTS FROM
THE RIVER WATER W/COOLING SYSTEM
ADDITIVES), COAL TAR & AMMONIA
WASTE WATER
13. BLOWDOWN FROM WASTE HEAT BOILERS
(WATER W/BOILER CONDITIONING
CHEMICALS, P)
14. SANITARY TREATED EFFLUENT
(CHLORINE, POLYELECTROLYTES, OILS,
BOD, BACTERIA)
15. GAS PURIFICATION WASTE
16. BY-PRODUCT PURIFICATION WASTE
17. QUENCH WATER (SLAG COOLING)
18. RUNOFF, STORM
-------
Coal Gasification 235
SULFUR RECOVERY WATER IF
A SATURATED Na2S04 PURGE IS TO EVAPORATION
USED — —
Figure 2: Wastewater Treatment
DEWATERED SLUDGE FROM WATER SOFTENING
POWER PLANT: FLY ASH
BOTTOM ASH
SCRUBBER SLUDGE
TO ENCAPSULATION
GASIFIER: ASH OR SLAG
IRON
Figure 3: Wastewater Treatment
SEPARATION:
HYDRAULIC OR
MAGNETIC
IRON
n = NUMBER OF STAGES
Figure 4: Wastewater Treatment
EXTRAPOLATED
0.5 1
"I 1—I TT
2 4 6 8 10 20
CAPACITY (10® gal/day)
40 60 80 100
Figure 5: Electrodialysis Equipment Costs
-------
236 Coal Gasification
combined in various advantageous ways. Figure 2 gives forma-
tion of a combined wastewater containing all the coal processing
and clean-up aqueous wastes including sanitary effluent
(excluding sanitary sludge). The stronger toxic, organic-
containing wastes are shown as treated by wet oxidation and
carbon adsorption. Dewatered insoluble residues (Figure 3) and
sludges are shown as being treated by a positive encapsulation
technique before landfill, sale, or other use. From the stream
containing the soluble salts (Figure 4), precipitable salts are
removed with a lime and soda softening, followed by sequestra-
tion of the remaining calcium with a polyphosphate in prepara-
tion for electrodialysis.
Use is made of electrodialysis (Figure 4) to recover a large
amount of water for re-use in the coal process and to prepare a
strong brine for subsequent treatment. With a strong enough
brine, it appears feasible to evaporate to dryness in the next step,
again recovering water for re-use. The final dry soluble salts are
then to be encapsulated by any of several techniques for use as
landfill or constructional materials. Encapsulation in the slag is
included as one possibility here.
The sequence of waste treatments proposed here has not been
reduced to practice as a totality on either commercial, demon-
stration, pilot, or laboratory scale, although each separate step
(such as wet oxidation, electrolysis, evaporation, and encapsula-
tion) has been proved as a new technology separately in
commercial applications.
The US Government has under way a program for demon-
stration plants, to be followed by commercial-scale plants for
the gasification of coal. For exploring the waste treatment
method outlined above, a demonstration plant size of 3000 tons
of coal per day (fed to the plant) was selected. The correspond-
ing commercial scale was taken as five times this amount in
quantity, but was identical as to stream compositions. These two
sizes correspond roughly to 60 and 250 million standard cubic
feet per day of pipeline gas, essentially methane.
Electrodialysis5
Electrodialysis is a method of concentrating dissolved ionic
species by "electroplating" them from a solution of a low
concentration into a solution of high concentration. In aqueous
solution it removes ionic impurities from the water6'7-8 rather
than removing the water from the impurities, as is the case with
reverse osmosis, distillation, and freezing. When impurities,
present as minor constituents to begin with, are to be removed to
low exit concentrations, the idea of dealing with these minor
quantities appears worthy of consideration because the major
constituent (water) is then available automatically and without
cost having been expended on it. The method has a high energy
efficiency and its proponents have been overcoming the eco-
nomic limitation of high cost of equipment for membrane and
cell. The apparent technical merit of the method is such that
electro-ion exchange membranes development will continue
and may achieve economic competitiveness. Brines of 200,000
ppm (20% salt content) are produced commercially from
seawater in Japan.' At the Roswell test facility of the (then)
Office of Saline Water, US Department of the Interior, tests
have shown that 20% to 25% brines can be produced from
waters of 1,000 to 50,000 ppm total dissolved solids.10
Electrodialysis has been well studied and applied to desalting
brackish and sea water" for municipal water supplies. In these
cases a very pure (potable) water is required. The cleaning up of
wastes to the point of being re-useable in coal processes is more
analogous to the cleaning up of industrial wastes, to which the
process has been applied in a number of cases. Cleaning up coal
waste is a much less stringent requirement than producing
potable water and is well within the technical capabilities of
electrodialysis. As a more closely related precedent, it has been
applied in the metal finishing industry, u As a waste-treating
process it generates a minimum of waste itself. It may be
contrasted to water and wastewater treating which requires
significant amounts of added chemicals that have to bedisposed
of, on the one hand, and to distillation or evaporation which,
like electrodialysis, do not require the disposal of large amounts
of added reagents. In all cases there is an irreducible minimum
blowdown or cleaning waste from the waste treatment, whose
disposal itself must be accounted for. Iron oxide or calcium salts
from the electrodialysis can be added to other sludges from the
coal process, or they can be settled and fed to the next operation
(described below) in admixture with the concentrate, in which
process the salts and sludge go completely to dryness.
For illustrative purposes sodium sulfate and sodium chloride
are considered as representative of the ionic species, although
others will be present in aqueous wastes from coal plants.
After meeting the requirements of operability for waste clean-
up, costs must be considered. The costs are for electrodialysis
energy, pumping energy, supplies, labor, and capital. Efficien-
cies such as for rectifiers, transformers, and current efficiencies
are significant. Other costs such as taxes and financing follow
from these and all may be offset by credits for usable or saleable
products.
High current densities can result in fouling on the dialysate
side. Electrodialysis may have to be preceded by oxidation,
clarification, and carbon adsorption, processes which by them-
selves will not deal with soluble salts. Incorporation of these
requirements is shown as part of the waste treatment system
(Figures 2, 3, and 4).
In the absence of a definitive study, good practice to date
indicates as a practical limit a 50% reduction in feed
concentration per stack of cells. Higher-temperature operation
may be developed to further increase the film conductivity and
to gain increased ion migration rate for a given current density,
i.e., a larger quantity of salts recovered for a given energy cost.
The electric energy requirement of an electrodialysis system
has been reported as decreasing approximately one percent for
each degree Fahrenheit that the feedwater is increased. In the
treatment proposed here, an increased temperature could lead
to a further benefit from feeding hot to the next operation
(evaporation).
Countercurrent13'14 electrodialysis has been described in the
literature, including a case of countercurrent electrodialysis with
reflux.15
A little-used,3'16 undeveloped modification of electrodialysis
may be used. In this modification pumping is eliminated by
making use of gravity and the cells are much wider. When a
concentrate is formed, its density is greater than that of tjje
dialysate, and the dialysate film itself is less dense than its bulk
solution. For a given current density, the increasing electrical re-
sistance of the depleted dialysate film results in an increased film
temperature, due to Ohmic heat. This effect further decreases
the film density, tending to cause the film to flow upward against
gravity. The membranes can, therefore, be arranged
electrogravimetrically, i.e., installed loosely, or even merely
hung in a tank. The depleted solution rises to the top header
while the concentrated solution falls by gravity to a bottom
header, flow thus taking place as natural convection. The
channels do not need to be narrow with expensive separators
and frames. The advantages are (a) construction is extremely
simple, (b) pumping energy requirements are negligible, and (c)
maintenance and fouling are severely reduced or eliminated.
The disadvantage at present is low throughput for a given size.
In normal electrodialysis the following costs are reported as
normally incurred:
Operating Costs:
Energy
1. Salt transfer (removal): 0.4 kwh/1000 gal/100 ppm
-------
Coal Gasification 237
removed.
2. Pumping: 2 kwh/1000 gal.
Supplies
3. pH adjustment 1 lb H2S04/IOOOgal/100 ppm of alkalinity
in the feed; 3 to 4 lb H2S04/100 gal for a hard brackish
water. Acid cost should not exceed 5e/1000 gal. This
adjustment has already been made upstream of the
electrodialysis unit.
4. Polyphosphate to sequester calcium, if over 400 to 500
ppm. The cost may be 1 c/1000 gal.
5. Polishing filter cartridges: 2 to 5c/1000 gal. These are not
needed on the dialysate because of centrifuging during
subsequent treatment of the concentrate and the permissi-
ble use of "dirty" water in the coal conversion process.
6. Membrane replacement: 5c/1000 gal for 2 stages, increas-
ing linearly to 10« /1000 gal for 4 stages and 15c/1000 gal
for 6 stages. The coal conversion example requires 4
stages.
Labor
7. Operation and maintenance labor: 2 to 4 man-hr/day for
plants up to and somewhat above 2 million gallons per
day.
Capital Costs
Capital costs are shown on Figure 5 for plants of the pumping
capacity shown, dimensioned according to good practice to be
reasonably economical and using 1974 dollars.
Economy of scale comes principally from rectifiers and other
electrical equipment. The stacks themselves are simply larger
numbers of identical units. Flow for the coal waste treatment
system shown in Figures 2, 3, and 4 is approximately 400,000
gallons per day (gpd) for a demonstration plant and 2,000,000
gpd for a commercial-size plant. The respective capita! costs for
n = 4 stages (from Figure 5) are 1.1 and 0.55 $/gpd, respectively,
indicating capital costs of $440,000 and $1,000,000, respectively.
Cost Summary
Capitalized operating and capital costs for the demonstration
and commercial sizes of plants have been calculated, using the
factors given above; the results are given in Table II. On the
same table, a "standard" cost is reported from the literature for a
1 -million-gallons-per-day (mgd) plant with a 2500 ppm feed and
500 ppm dialysate (potable water), operating at 90% capacity.
The coal waste treatment costs compare favorably with the
"standard."
The method is seen to be operable, its present costs are in line
with use in other applications, it generates a minimum of wastes
on its own account, it saves water, and, environmentally, it
appears to be a step toward zero liquid discharge of soluble salts
for the coal conversion plants.
Oil-Fluidized Evaporation
Historically, evaporation is an old operation. More recently,
however, adaptation of the principle of steam distillation to
evaporation provides a convenient way to evaporate completely
to dryness.17 In this process, oil of the correct volatility,
viscosity, and surface tension is added to the aqueous waste and
the mixture is fed to a multiple-effect, falling-film evaporator.
The mixture passes through the evaporator, leaving the solids
suspended in the dry oil as a fluid slurry. The oil is then
centrifuged off to be used again, and the dry solids are left.
Water is recovered for re-use in the coal process (Figure 4), the
oil is recycled, and the water-soluble solids emerge in a dry
powder form. This form is suitable for encapsulation to permit
final disposition of the salts as insoluble forms that will not
contaminate water in the envirnoment.
The oil maintains fluidity throughout the system, improves
heat transfer in the evaporator, and prevents scaling and fouling
as the salts become completely dry. This patented technique is
efficient for the removal of water without problems of thicken-
ing, scaling, and fouling.
It is reported that oil-fluidization plants have turned out to
cost approximately one-third less than equivalent spray-drying
or incineration plants.18 due mainly to economies of multiple-
effect heat utilization. Evaporation is energy-intensive but the
use of a strong brine as feed, along with multiple-effect heat cost
savings, bring it within the limits of reasonable economy, given
that clean-up of the aqueous waste is required. The process is
well proved commercially.
The oil evaporation technique is appropriate for a coal
Table II: Electrodialysis Costs
LITERATURE CASE
"STANDARD"
COAL CONVERSION
DEMONSTRATION UNIT COMMERCIAL UNIT
S/1000
GAL FEED
S/1000 S/YEAR
GAL FEED
S/1000 S/YEAR
GAL FEED
TOTAL COST 0.65
1.07 155,855
0.76 558,450
ABOVE COSTS INCLUDE:
ENERGY (1.7 CENT/KWH)
LABOR
ELECTRODIALYSIS
PUMPING
OPERATING
MAINTENANCE
SUPPLIES
CAPITAL (15%/YEAR
AMORT.)
CHEMICALS, FILTERS
MEMBRANE REPLACEMENT
-------
238 Coal Gasification
conversion plant, as a suitable oil is at hand in the form of the
products of coal conversion.19 A desirable oil that has been used
in the oil evaporation process is Isopar H,M properties of which
are shown in Table III. The properties of some representative
liquids derived from coal, using a hydrotreating process, are also
shown. It is seen, by comparing gravity, viscosity, and vapor
pressure (or boiling-range) that unhydrotreated oil is too
viscous to use as a conventional evaporator oil but that, after
hydrotreating, the light oil21 fraction is a suitable oil. There is no
theoretical reason standing in the way of using the phenols
traction as the evaporator oil. This could be a small diversion
from saleable products to be used as make-up oil, or it could be
once-through on the way to incineration.
The oil, of whatever type, withheld from sales would be only
make-up. Most of the oil would be recycled into the evaporation
cycle, and the oil purge, if viscous impurities collect, would be
recycled into the coal conversion process. The vapor pressure of
the oil is such that about one pound of oil is vaporized with ev-
ery pound of water. This can be diminished or augmented as
desired by selecting oil fractions of appropriate boiling range.
The cooled oil can then solvent-extract organics out of the
water, which is then recycled to electrodialysis or elsewhere in
the coal process as needed (Figure 4).
For evaporation equipment, cost has been explored" as
affected by feed concentration and feed rate (scale-up). The
economies of scale-up in feed rate (five times) are apparent from
the figures summarized in Table IV. It is also apparent that
pronounced economies result from designing for the higher feed
concentrations.
There is an interaction between the costs of electrodialysis and
evaporation. With a given feed rate and concentration, the cost
relations for electrodialysis show increasing costs, both capital
and operating, when generating a stronger concentrate. This is
so simply because more demineralization (percent reduction of
feed concentration) requires more stacks in series, and more
pounds of salt electrolyzed per day require more current. For
evaporation, as described above, an opposite relation holds,
with the result that combining costs of the two processes can
result in an optimum value for salt concentration in concentrate.
Figure 6 portrays schematically the interaction of costs for the
two operations. In this paper the supposed optimum has been
taken as 20% sodium sulfate in the electrodialysis concentrate.
Encapsulation: Bitumens and Sulfur
When the soluble salts are dried to a fine, free-flowing
powder, they would be readily mixed into any bituminous
material such as might be used for road paving or roofing
compositions. Some of the coal processes produce tar which
may be recycled and finally gasified to extinction. However, the
tar could be considered as a medium to encapsulate the soluble
salts and store them in that fashion permanently as a form of
landfill. This method appears potentially economical, but it is
not known to be commercial and data on feasibility and
weathering are not available.
In a similar vein, the 33% silica in a sulfur composite2*
material might be partially replaced by dried soluble salts. The
sulfur is necessarily produced by most of the coal conversion
processes now planned because of increasing scarcity of low-
sulfur coal. The sulfur composite with salts could then be
fabricated, as is presently proposed with silica, into acid-re-
sisting pipe, etc., if that industry develops. Of more practical
Table III: Properties of Some Evaporator Oils
Property
Gravity, °API
Specific gravity
Flash point, °F
Viscosity
Pour point, F
Freezing point, 0 F
Isopar H
55.2
60
>¦75860
123
0°C
25°C
100°C
COED
Syncrude
2.2 cp
1.3 cp
0.98 cp
Hydrotreating
H-3 light
fraction
From IBP |
Feed to 400° F
100°C 3.4 cs
49.0
<- 2.4 cs
-30
2391
sus
-129
• 32
sus
ASTM distillation
IBP
95%
100%
Vapor pressure, psia
345
366
100° F
150° F 0.26
200° F 0.95
250° F 2.6
190
720
400
1.1*
Heat of vaporization
Btu/lb
Surface tension
dynes/cm., du Nuoy
interfaciai tension
dynes/cm., du Nuoy
Solubility
Water in oil, ppm
Oil in water, ppm
77°F 138
212°F 123
atm.b.pt. 110
1.03
0.001
NOTES: cp * canlipoitei
ct » centistokai
tut * Saybolt univertal sacondt
IBP - Initial Boiling Point
' fleid vapor prettura.
Table IV: Evaporation Costs
DEMONSTRATION UNIT
COMMERCIAL
UNIT
FEED CONCENTRATION, WT % SALTS
20
1.32
20
1.32
FEED RATE, POUNDS/HOUR
8,000
127,868
40,000
631,000
NUMBER OF EFFECTS
3
6
4
6
100 PSIG STEAM, LBS/HR
3,200
31,500
12,000
157,500
COOLING WATER, GPM
285
5,600
1,422
28,000
LABOR, 24 HR DAY, MEN
1
1
1
Vh
CAPITAL COST, S
374,500
2,386,500
864,000
6,270,000
-------
Coal Gasification 239
value, perhaps, would be to use the salt-bearing sulfur to form a
landfill, to underlay tillable soil, etc. Its bright yellow color
could even be interesting in landscape architecture.
Progress has been made in overcomingthe obstacles to the use
of sulfur as a cementing agent for aggregates,23 Sulfur and
aggregate concretes have excellent strength properties, and re-
sistance to weathering has been improved with proprietary
additives. Portland cement-grade aggregates are satisfactory
and aggregate containing significant amounts of organic matter
and silt, which are often unacceptable for Portland cement
concretes, may be used successfully. It is hypothesized by this
author that dried soluble salts could be encapsulated in this
material along with organicsand silt. The developer of the sulfur
concrete is Sulfur Innovations, Ltd., of Alberta, Canada.
Another application that might be capable of utilizing dried
salts is road paving.24,25 Road trials have taken place in Europe
and in the United States (Texas, September 1975) in which a
bitumen surface containing sulfur was placed on a heavily
traveled road. The sulfur in this application does not need to be
pure and could probably be the product from using sulfur to
encapsulate dried salts.
Encapsulation: Pozzolanic Method
A body of technology is developing for protecting soluble
salts from weathering.
The dried, free-flowing, soluble solids from evaporation are
to be encapsulated for permanent storage so as to not re-enter
the environmental water cycle (Figure 4). A commercially
feasible method is that marketed under the name Poz-O-Tec. In
this method the salts are blended with fly ash, alumina, silica,
and lime in the proper proportions, and are caused to harden as
a cement-like monolith of very high density.26 This would serve
as paving, landfill, brick, road embankments, strip mine
reclamation; it can be used to underlay crop-yielding soil,
artificial lakes, etc. The author is of the opinion that all the
insoluble residues listed earlier in this paper can be encapsulated
in this manner, if necessary, to prevent the leaching of soluble
salts. The soluble salts can be considered, as a gross over-
simplification, to be equal parts of sodium sulfate and sodium
chloride. The sulfate is ideally suited to encapsulation by means
of this pozzolanic method since one of the most important
insoluble compounds formed when the mixture sets up is a
calcium sulfo-aluminate. The entire mass is so impermeable that
sodium chloride or other soluble salts distributed through it will
not be reached by water and, therefore, will not leach out.27 A
nominal amount of leaching of the external surface occurs and
diminishes rapidly with time. There is no leaching from the
internal surfaces. Since it is the total mass of transportable salts
that is of environmental concern, not the concentration in the
initial leachate, the method minimizes pollution from leaching.
For a demonstration-size plant (3000 tons of coal per day),
using the pozzolanic method, the estimated 10-foot landfill
areas would be: for one year, 0.435 acres; for 10 years, 4.35 acres;
and for 20 years, 8.7 acres. For a commercial plant, the figures
would be five times as great.
Water can be forced slowly into the fill for experimental
purposes if a depth of 90'feet of water is used. This is not likely to
happen in the natural environment. Thirty years would be
required to fill the small amount of porosity of a 10-foot-thick
bed under conditions of rainfall of '/£ inch per 24 hours and 30
inches per year, with no runoff or evaporation. The penetration
rate under these conditions is approximately 4 inches per year of
water going in and none coming out. The compacted material
actually used is graded and drained to permit runoff and to
minimize the accumulation of standing water.
Compressive strength develops rapidly28'29 so that, as a
landfill, the completed fill is valuable for nearly every imagina-
ble land use. Because of its strength it can be disposed of at a
slope that depends on such considerations as final contour
desired and retention of cover material rather than on stacking
stability. However, before hardening, the fill will conform to a
wide variety of disposal areas from low flat land along coastal
and tidal areas to hilly natural ravines.
The cost of using the technique is sensitive to throughput (vol-
ume of waste handled). Waste stream stabilization is quoted at
from 3 to 15 cents per gallon for 10 gallons per minute,
depending upon the end product, cost of materials added,
transportation, and volume of waste stream. The process has
been used to encapsulate aqueous wastes from 56,000 to 160,000
ppm dissolved solids.
In the coal conversion waste treatment, aqueous streams from
any of three points could be directed to encapsulation; before
electrodialysis (eliminating it), after electrodialysis (eliminating
evaporation), or after evaporation. The concentrations of the
salts at these points is successively greater and the volume of
waste is correspondingly less. The lesser volume indicates lesser
annual costs for encapsulation by way of both capital and
operating costs, and both have an opposite relation to electrodi-
alysis. This situation indicates the existence of an optimum
combination based on various degrees of concentration
achieved by electrodialysis and evaporation, including the effect
of omitting one or both. If costs for various combinations of the
three operations are displayed as functions of exit concentration
from electrodialysis versus exit concentration from evapora-
tion, it is expected that on such a plot an optimum, least-cost
configuration would emerge. It is recognized that the least cost
could result from pozzolanic encapsulation alone. It is here
assumed that evaporating to complete dryness, and combining
with dewatered sludges and as much wet slag as needed, will
provide the requisite moisture and solids for optimum encapsu-
lation economics.
Encapsulation: Slag Method
The presence of slag in the coal conversion gasifier offers the
opportunity to use the slag to encapsulate the soluble salts that
are produced as solids from the evaporation step. The salts will
be strong in alkali metals, with calcium, magnesium, and other
constituents. These materials can interact with refractories to
cause fluxing. The following brief list of known compounds,
taken from various refractory phase diagrams, indicates the
serious degree of melting point lowering that can result from
addition of sodium, calcium, and certain other metals to
refractories:
System or compound
Nk'ltini: pom! or
lowest fiw/ini:
pomi (C )
Components
StO-,
171U
Compound
AM),
:i)5o
Compound
CuO
_57>
Compound
MgO
:nuo
Compound
Sit)-, I'bO
7 1 5
Ilin.HA
Nj,0 2SiO,
N"M
Compound
SiO:-K,0 AUO, -4SiO,
1050
l - (»SiO> • AM),
1 too
Compound
Nu,() • 3CaO • <>SiO,
10-17
Compound
CuO • l:e,0.
\2\U
Compound
2CilO ¦ Fc,0,
14.!(»
Compound
SiO<»-CuO-Na-,0
725
1 criMi v Minimum
SiO, -GiO-Na-,0
740
1 crn.irv Minimum
-------
240 Coal Gasification
SiO, ()
SiO, CaO Nj,()
NaCI
Nj:SC)4
V? I
x:>
10*0
XI JO
xx4
I M 1. 11 \ Mill
Iu„,h Mm
I vi n.ii \ Mill
( «> 111 (>< >111 M I
Internetional Critical Tables, 1930
Hand boo.v ot Ctiewisu
and Physics,
At the temperatures of the gasifier, alkali metal oxides have
an appreciable vapor pressure. In the reducing atmosphere of
the gasifier they can form sodium and potassium vapor.
Experience with blast furnaces30 has shown that these metals
and oxides will volatilize, form a fume, and will either accumu-
late in the gas offtake pipes or collect in condensates. Eventually
they will arrive back at the wastewater treatment plant, and thus
build up somewhere in the coal conversion process instead of
being removed.
In fluidized bed incineration of chlorides it has been found
that alkali chlorides are volatile enough to plug the exhaust gas
ducts and that they also form hydrogen chloride. Sodium sulfate
and chloride form a low-melint eutectic {1154° F) which accum-
ulates in the fluidized bed and causes defluidization. The same
could be expected to happen in a fluidized bed gasifier.
It is concluded that because of fume formation and fluxing
action, adding the soluble salts to the gasifier is not to be recom-
mended.
When the slag leaves the gasifier it drops into water in a closed
vessel to form a frit, rather than cooling to large chunks of glass.
As the alkali metals reduce the melting point of the slag, it may
be possible to inject the dried solids into the molten slag by
holding and mixing in a bowl or tray just above the quench
water or just below the slag tap. At these lower temperatures the
alkali chlorides could possibly dissolve in slag without excessive
volatilization. Any small amount of residual volatilization of
chlorides would collect in the quench water, and would be
eventually carried back to the wastewater where it would be
dried up and again sent to slag. The net result would be
encapsulation of chlorides. The sulfates may react with silica in
the slag to form sulfur dioxide:
Na2S04 + 3Si02 = Na20 ¦ 3Si02 + S02 + 1/2 02
The S02-contaminated vapor and water would be introduced
into the already-existing acid gas removal system, particularly if
the sulfur clcan-up process already in the coal conversion
process is of the type that handles sulfur dioxide (the Stretford
process, for example) instead of hydrogen sulfide. Thus a small
increase in the amount ofelemental sulfur product from the coal
plant could be realized. Alternatively, the sulfur dioxide could
be recycled by introducing it into the pH adjustment step ahead
of electrodialysis.
Depending upon the proportion of silica, calcium oxide, and
iron oxide present, high-melting compounds can form:31
Devitritc
Na2() • 3CaO • 6SiC>2
1886°F
Na-,0 • 2CaO ¦ 3SiO,
2343°F
Acmite
Na20 • l-'e203 • 4Si()2
17S1°F
Albite
Na20 • Al20, • (>Si()2
2026°F
Nephaline
Na20 • Al203 ¦ 2Si02
2336°F
Nephaline-albite
butectic
1954°F
C/5
O
O
C3
Z
P
<
tr
UJ
a.
O
a
z
<
a.
<
u
CONCENTRATION, ELECTRODIALYSIS CONCENTRATE,
CONCENTRATION, EVAPORATOR FEED
OPTIMUM
CONC.
10
electboojalvsis^
100 1000
10000
100000
Ppm
10
Figure 6: Cost Interaction
10 20 30
W/t%
-------
Coal Gasification 241
1'he salts must be present in a fine state of subdivision in order
to react well, and this is attainable from oil-fluidized evapora-
tion. Alumina is normally present in coal ash and slag, but if
augmentation of alumina content is required, naturally fine
clays (Si0,-AL203 compositions) can provide Si02 to decom-
pose Na,S04 to Na,0 • Si), and A1203 to convert this to
crystalline high-melting sodium aluminum silicates. Kaolin clay
can dehydrate, then react with chlorides to produce hydrogen
chloride. It is assumed here that this reaction can be minimized
by avoiding high temperatures, and that any small residual
hydrogen chloride will collect in the S02-contaminated vapor
and water and eventually return from wastewater to slag by way
of evaporation.
From the standpoint of melting points and liquid mixing, the
method appears technically feasible. Whether the resulting
encapsulation would result in sufficient insolubility, and
whether the scheme would be actually operable, is not known.
CONCLUSION
A combined waste treatment has been studied for the ultimate
disposal of soluble salts from proposed coal conversion plants.
I he use of pozzolanic encapsulation to dispose of soluble salts
appears to be indicated when a zero liquid discharge is required
with or without concentration or drying of the salt-bearing
aqueous waste. Further, a reduction in cost of this treatment
appears to result from using evaporation before encapsulation.
For this step, oil-fluidization appears attractive as being able to
handle "dirty" oils, tars, salts, and dusts in water. The cost of
evaporation apparently can be reduced by incorporating
electrodialysis ahead of it. A question here is how much
pretreatment and polishing are required to make electrodialysis
operable.
There appears to be a lowest-cost configuration when
combinations of the three processes are explored over different
salt concentrations existing from each operation. It is felt that
further study is warranted to define the low-cost configuration
and possibly to explore the capabilities of theelectrogravimetric
configuration, which would eliminate the pretreatment of the
waste treatment.
Encapsulation of the dissolved salts in hot slag from the coal
gasifier appears to be a theoretical possibility for disposing of
soluble salts. Encapsulation in slag has experienced a limited
experimental success. Encapsulation in sulfur is also a possibil-
ity. Massive use of sulfur is an emerging technology; incorpora-
tion of soluble salts has not been investigated.
Commercial application has been achieved by vendors of each
of the three operations: pozzolanic encapsulation, electrodialy-
sis, and oil-fluidized evaporation. Encapsulation in pozzolanic
material, bitumens, or sulfur offers the possibility of using the
resulting water-impervious, massive material from the demon-
stration plant to form such .features as lackes, land contours,
streets, and site preparation for both demonstration and
commercial plants, and as foundation support for the commer-
cial plant.
The conclusion from the study is that the three operations
mentioned can be assembled, with a minimum of risk, into a
process that will be useful for the ultimate disposal of soluble
salts. Indeed, it gives promise of becoming a best-available
technology for achieving ultimate disposal of waste-soluble
salts.
REFERENCES
1. Ferretti, E. J., "Design Concept for a Coal Hydrocarboni-
zation Plant," Chemical Engineering Progress, 72 No. 8,
August 1976, p. 62.
2. Morgan, W. D„ "Coalcon's Demonstration Plant for Clean
Fuels," Chemical Engineering Progress, 72, No. 8, August
1976, p. 64.
3. O'Hara, J. B., Jentz, N. E., and Khaderi, S. K., "Fischer-
Tropsch Plant Design Criteria," Chemical Engineering
Progress, 72, No. 8, August 1976, p. 65.
4. Jahnig, C. E., "Environmental Aspects of Coal Gasifica-
tion," Chemical Engineering Progress, 72, No. 8, August
1976, p. 51.
5. Nachod, F. C., and Schubert, J., "Ion Exchange Technol-
ogy," Academic Press, Inc., New York, New York,1956.
6. Water Purification Associates, Cambridge, Massachusetts,
and Process Research, Ind., Cambridge, Massachusetts,
"Innovative Technology Study," The National Commis-
sion on Water Quality, Contract No. WQ5AC089, August
1975.
7. Winger, A. G., Bodamer, G. W., and Kunin, R., "Some
Electrochemical Properties of New Synthetic Ion Exchange
Membranes," J. Electrochemical Society, 100, No. 4, April
1953, p. 178 ff.
8. Probstein, R. F., Sonin, A. A., and Spielman, L. A., "Water
Purification," Short Course Notebook, AIAA, New York,
New York, 1972.
9. Asahi Chemical Industry Co., Ltd., "Ion Exchange Mem-
brane and Its Application," company brochure, undated.
10. Lynch, M. A., and Mintz, M. S., "Membrane and Ion-
Exchange Processes—A Review," J. American Water-
works Association, 64, No. 11, November 1972, p. 181 ff.
11. Langelier, W. R., "The Electrochemical Desalting of Sea
Water with Permselective Membranes—A Hypothetical
Process," J. American Waterworks Association, 44, No. 9,
1952, p. 845 ff.
12. Bramer, H. C.,and Coull, J., "Electrolytic Regeneration of
Spent Pickling Solutions," Industrial and Engineering
Chemistry, 47, No. 1, January 1955, p. 67 ff.
13. Private communications, Water Purification Associates,
Cambridge, Massachusetts, April 1977.
14. Winger, A. G., Bodamer, G. W., Kunin, R., Prizer, C. J.,
and Harmon, G. W., "Electrodialysis of Water Using a
Multiple Membrane Cell," Industrial and Engineering
Chemistry, 47, No. 1, Jarnuary 1955, p. 50 ff.
15. Spiegler, K. S„ "On the Electrochemistry of Ion-Exchange
Resins—A Review of Recent Work," J. Electrochemical
Society, 100, No. 11, November 1953, p. 303C ff.
16. Brown, J. H., and Conning, D. G„ Electrogravitational
Dialysis Apparatus, U.S. Patent No. 3,294,671. December
27, 1966.
17. Rosenblatt, T. M., "Optimization and Design of an Oil
Activated Sludge Concentration Process," U.S. Environ-
mental Protection Agency, Cincinnati, Ohio, Report No.
EPA-670/ 2-74-004, Esso Research and Engineering Com-
pany, Contract No. 68-01-0095, February 1974.
18. Brown, J. A., "The Carver-Greenfield Process," Technical
Memorandum of Dehydro-Tech Corporation, 1976.
19. P rivate communications, Dehydro-Tech C orporation, East
Hanover, New Jersey, owners of the Carver-Greenfield
process for oil-fluidized evaporation, February-April 1977.
20. Humble Oil and Refining Co., Isopar H specification sheet.
21. Jones, J. F., Schoemann, F. H., Hamshar, J. A.,McMunn,
B. D., Scotti, L. J., and Eddinger, R.T.,"Char Oil Energy
Development," Office of Coal Research, R&D Report No.
73, Interim Report No. 1, Contract No. 14-32-0001-1212,
July 1, 1971 to June 1972, FMC Corporation, Princeton,
New Jersey.
22. McBee, W. C., and Sullivan, T. A., "Sulphur Composite
Material," Sulphur Institute Journal, 11, No. 3-4, Fall-
Winter 1975, p. 12.
23. Anonymous, "Sulphur Concretes Go Commercial," Sul-
phur Institute Journal, 12, No. 2, Summer 1976, p. 2.
-------
242 Coal Gasification
24. Anonymous, "Suophur-asphalt Trials in Texas," Sulphur
Institute Journal, 11, No. 3-4, Fall-Winter 1975, p. 2.
25. Anonymous, "Sulphur-asphalt Road Trials Carried Out in
Europe," Sulphur Institute Journal, 12, No. 3-4, Fall-
Winter 1976, p. 4.
26. Private communications, IU Conversion Systems, Inc.,
Philadelphia, Pennsylvania, owners of Poz-O-Tec and
related processes, April 1977.
27. Mullen, H., and Taub, S., "Tracing Leachate from
Landfills—A Conceptual Approach," presented at
National Conference on Disposal of Residues on Land, St.
Louis, Missouri, September 14, 1976.
28. Mullen, H., Ruggiano, L., and Taub, S. I., "The Physical
and Environmental Properties of Poz-O-Tec," presented at
the Engineering Foundation Conference on Disposal of
Flue Gas Desulfurization Solids, Hueston Woods State
Park, Ohio, October 19, 1976.
29. Taub, S. 1., "Treatment of Concentrated Waste Water to
Produce Landfill Material," presented at International
Pollution Engineering Exposition and Congress, Anaheim,
California, November 10, 1976.
30 Snow, R. B,, "Effect of Chemical Attack and Operational
Parameters on the Wear of Blast Furnace Refractories,"
prepared for U.S. Energy Research and Development
Administration, Report FE 3731-1, Contract No.
E(49 18)3731, 1976.
31 Becker, K. P., and Wall, C. J., "Huid Bed Incineration of
Wastes," Chemical Engineering Progress, 72, No. 10,
October 1976, p. 61 II.
-------
EPA's Research and
Development Program
for the
Nonferrous Metals Industry
George S. Thompson, Jr.
Industrial Environmental Research
Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio
As a result of a recent reorganization within EPA's Office of
Research and Development, a new laboratory entitled the
Industrial Environmental Research Laboratory was formed.
One function of this laboratory is to conduct research, devel-
opment, and demonstrations of control technologies that can be
used to minimize the discharge of air, water, and solid waste
pollutants from various industrial sources. 1 will, during the
remainder of my presentation, describe one of the Laboratory's
most significant programs, the research and development
program for the nonferrous metals industry.
The nonferrous metals industry includes, from a processing
standpoint, the mining and beneficiation of nonferrous ores, the
extraction of the desired metal or metals from these upgraded
ores, and lastly, the refining of these metals into salable prod-
ucts. For simplicity, EPA's research and development program
has divided this industry into three distinct segments: the major
primary nonferrous metals such as aluminum, copper, zinc, and
lead; the minor primary metals including, but not limited to,
arsenic, cadmium, selenium, molybdenum, and vanadium; and
the secondary nonferrous metals. In total, there are
approximately 500 facilities in the United States that are
producing nonferrous ores, concentrates, and metals. These
facilities are diversified in geographic location, with some plants
located in isolated regions of the Southwest, while many are
situated in highly urbanized areas.
With this basic introduction, I will now describe EPA's
research and development program for the nonferrous metals
industry. This program is multimedia in scope; that is, it
addresses the various environmental media such as air, water,
and solid waste. Research, development, and demonstration of
various control technologies are conducted through such
mechanisms as grants, contracts, interagency agreements, and
international activities. Various methods are used to select the
research and development projects that will have the greatest
effect on pollution abatement. One such method is conducted
through the multimedia environmental assessment.
This assessment has just been completed and is currently
being reviewed. It first comprehensively defines the nonferrous
industry as subindustries producing 36 primary metals and 18
metals by secondary means. Each industrial process that is used
to produce these primary and secondary nonferrous metals is
then described and investigated in detail. Feed materials, energy
consumption, products, and byproducts are quantified. Envir-
onmental discharges to the air, water, and land are then de-
scribed and quantified to the best extent possible. When
insufficient emission data exists, the multimedia discharges are
semi-quantitatively described by investigating the production
process, its inputs and its outputs. The pollutants that are
identified are any pollutants for which data exists. The assess-
ment directs its emphasis at not only the broad-based pollutants
such as total suspended solids, total particulate matter, and
sulfur dioxide, but also specific metallic and organic constitu-
ents. After the "real world" processes and their environmental
discharges have been described, the existing control technolo-
gies which are applied to these multimedia discharges are then
investigated. The pending publication can best be described as
the most recent compilation of process and environmental data
on the nonferrous metals industry. It is voluminous in size;
current plans call for publication of this data base in a format
that can be periodically updated so that its content will be
dynamic in nature.
This extensive data base was then used to prepare an
environmental impact summary report. This report determines
the significance of the remaining multimedia discharges de-
scribed in the assessment data base. It also describes the
adequacy of presently applied control technology. Clearly, this
impact summary report provides a rationale approach to
determining which research, development, and demonstration
activities should be conducted in order to be most beneficial to
the environment, the EPA, and the industry. This approach is
essential when limited research funds must be used to solve an
extensive number of environmental problems. One other prod-
uct of this impact summary report is an awareness of the
"missing" data.
I will now provide an example of how this procedure led to an
important finding. The nonferrous metals assessment data base
described the primary copper smelting industry's reverberatory
furnace in detail. Feed materials, whether for a calcine or a
"green feed" charge reverb, were described; fuels and energy
consumed during smelting were tabulated. Considerable infor-
mation was found that described the atmospheric discharge of
total particulate matter, sulfur dioxide and sulfur trioxide.
Detailed data were also found that described reverb slag
granulation water, as well as the slag, itself, as a solid waste.
Only limited data on trace metals existed, especially for such
highly volatile metals as arsenic. Control technologies, includ-
ing slag granulation water recycle and particulate matter
collection devices, were described but just in the broad pollutant
sense. Descriptions of electrostatic precipitators centered
around the collection of total particulate matter and again, an
insignificant amount of information was found relating to the
collection of specific pollutants such as lead, zinc, cadmium, and
arsenic. During the preparation of the environmental impact
summary report, concern always centered around the discharge
and ultimate fate of trace metals. This concern, along with an
engineering assumption that such highly volatile metals as
arsenic could not be effectively collected by high temperature
electrostatic precipitators, led to a research sampling and anal-
-------
244 f I'A's R&D Program
. ¦ i _nfi imrtiemented to causing a purge of the recycle stream. This purge is. of course, of
ysis program. This program was designed ana imp significant environmental importance due to its teachability and
fill in the missing data in the assessment s ^ .ndenth highly toxic nature. The results of this grant effort will lead to
Several reverberatory furnaces were selecteo i thc demonstration of alternate disposal or usage techniques that
testing. Sampling methods such as 'n-stac^out- . , th(. industry can cost-effectively employ to meet (uture EPA leg-
wet electrostatic precipitator, and impac islative mandates.
produce the best results. ^inWnt When In the area of process wastewater, several concurrent efforts
The results were as predicted by ^S^eenng.Vmn C) the are simultaneously being conducted u> demonstrate or docu-
operating at a high temperature like: 60t ( J. mentlheapPlication of control and treatment technologies. The
electrostatic precipitator "sees only the Pa"™u . . cess wastewaters generated by the nonierrous metals indus-
which exists at this high temperature. If designed t ^ ^ ^ generally acidic in nature with high concentrations of
temperature and maintained and operated eniu<:i j, dissolved metals. These metals are the same metals found in the
precipitator will effectively collect this particulate_ m . orlglna) orcs. The research program has lour directions in its
sampling and analysis program revealed that the nig y approach. Existing wastewater control technologies such as
metals such as arsenic existed primarily in he gaseou s a ^ and
reuse are being investigated and documented,
while passing through the electrostatic precipita'tor to Disseminating thc documented results of these technologies will
toxic constituents leave the precipitator and the oiigas ¦ enab|e br()ader application by thc industry. Existing precipita-
stack and ambient temperatures, the gaseous meta , l . ,jon technologies such as "lime-and-settle" are being investi-
into fine-sized particulate matter and are released u from (he sta|ldpoint 0| better system design and better
ronment. Therefore, even though an existing conm remova) through more prolicient operation and mainte-
maintains a high collection efficiency as designed it'w ' nance. Hopefully, this effort will allow the industry to"upgrade"
designed for optimum performance, allow specmc, ci existing conventional "end-ot-pipe" treatment technology in
mentally impacting pollutants to be discharged. ordcr t0 meet future regulations. Advanced precipitation
This example illustrates the fact that the assessment at y technologies such as soluble and insoluble sulfide precipitation
predicted a potential and significant problem area dui, a ^ investjgated and a demonstration on metal-bearing
same time, indicated that insufficient data on trace. m . ss was,cwatcrs is planned in the near future.The
existed. Once the missing data were collected the impac foimh djrection in thc program's efforts to minimize water
problem was established and a research, development pollution addresses advanced treatment technologies such as
demonstration need "surfaced. divine starch xanthate, ion exchange, and ultrafiltration. The planned
Determining the problem is, of course, important, dux s b ^ produclo(theabove,ourapproacheswillbeasertesofcost-
the problem is of equal importance. As the ne
-------
Leaching Studies and
Cation Exchange Properties
of Coal Fly Ash
John F. Gaasch
Fredonia Wastewater Treatment Plant
Fredonia, New York
and
Kam S. Law
State University of New York
Buffalo, New York
INTRODUCTION
Because of increasing energy requirements and the predicted
shift to coal over other energy sources, the production of fly ash
will rise above the present level of about 30 million metric tons
per year. Most of the fly ash that is collected by electrostatic
precipitators in electric power generation plants is disposed of in
landfills. Safe disposal or other use of fly ash, for example as a
soil amendment, requires a precise definition of its properties.
As part of a project designed to assess the environmental
impact ol a fly ash disposal site located near Dunkirk, New
York, an investigation of leaching and ion exchange properties
of fly ash was carried out. Water drawn from wells placed in the
site exhibited variations in pH and metal ion concentrations that
suggested the need for controlled laboratory experiments.
Fly ash derives from the mineral content of the coal burned.
Intrusions of clay, quartz, calcium carbonate combine with the
metal content of the coal at the high temperatures of a
pulverized coal furnace to produce primarily an aluminosilicate
glass combined with oxides and salts of iron, calcium, sodium,
magnesium and other metals.1 A small portion of the material is
soluble and could be carried from the landfill site by leaching of
rainwater. In an attempt to understand this process, accelerated
leaching studies and measurement of the capacity of fly ash to
retain some soluble cations via ion exchange were carried out.
Experimental
Sample Collection. Fly ash samples were obtained from the
Niagara Mohawk Corporation Power Plant located at Dun-
kirk, New York and were collected from the electrostatic
precipitators. Coal fired at the plant is obtained from various
eastern U.S. mines and mixed in storage piles prior to burning.
Samples of ash were removed from transfer ducts prior to any
contact with water. A sample of ca 50 kg was collected on each of
two days in June, 1975 (Fly Ash A) and June, 1976 (Fly AshB).
These two samples were used in leaching and ion exchange
experiments, as noted. Thirteen additional samples were col-
lected over the months of September and October 1976 for
leachate pH and sulphate content determination.
Leaching Methods. Separate mixtures of 50 g fly ash and 100
ml liquid were shaken at 22-24° C in polypropylene bottles for
0.5, 1, 2, 4, 8, 16, 32, 64, and 128 hours. The shaker bath was
adjusted to the minimum rate required to hold the solids in sus-
pension. The leaching liquid was water or water with the appro-
priate amount of hydrochloric acid or sodium or potassium
hydroxide used to modify the pH as desired. The bottles were
removed from the shaker and centrifuged immediately. The
liquid layer, between floating and compacted solids, was
sampled for analysis. Conductivity, pH and concentrations of
Ca, Cr, Fe, K, Mg, Na and Zn in the leachates were determined.
Sulphate Content of Fly Ash. Mixtures of 25 g fly ash and 50
ml water were shaken for 20 minutes and allowed to stand
overnight. After the pH of the supernatant was determined, 50
ml of a standard solution of BaCl2 was added and the mixture
shaken for 2 hours and allowed to stand overnight. The residual
barium content of the supernatant was determined. Sulphate
content was calculated from the loss of barium from the
supernatant.
Ion Exchange Methods. Fly ash was washed free of soluble
components and any metal cations present by shaking alternate-
ly with 1 M hydrochloric acid and 1 M sodium chloride (twice
each) followed by shaking with three portions of 1 M hydroch-
loric acid. The time for each shaking was about two hours. The
fly ash was then washed repeatedly with carbon dioxide free
distilled deionized water until the pH rose to 4 and was checked
for the absence of chloride.2 The fly ash was dried at 100° C and
tumbled using ajar mill (without abrasives) to homogenize the
sample. The resulting "acid form" of fly ash was converted to a
sodium form by the addition of an excess of 0.1 N sodium
hydroxide and shaking for 48 hours. The excess sodium
hydroxide was then washed from the fly ash by repeated shaking
with water, decanting and centrifuging until the supernatant
exhibited a conductivity of 4 micromho cm-'. The resulting
"sodium form" of fly ash was dried at 100° C and homogenized
for use in the isotherm experiments.
The determination of isotherms was carried out by weighing
15.0 g portions of sodium form of fly ash into polypropylene
bottles. Successively larger volumes of prepared standard
solutions of K, Cr(+3), Mn(+2), or Zn(+2) as chlorides were
added to each bottle. Water was then added to provide a total
volume of 100 ml of liquid phase. After shaking for 48 hours the
samples were centrifuged and the supernatant analyzed for
sodium and the competing metal cation. Ion exchange capacity
used for the calculation of isotherms was determined by adding
a known excess of 0.1 N sodium hydroxide to acid fly ash,
shaking for 48 hours and backtitrating a portion of the
supernatant with hydrochloric acid.
Ion Exchange Capacity. A number of 25.0 g portions of acid
form fly ash were weighted into polypropylene bottles. To each
bottle was added 60 ml of aqueous solution that was 0.25 N in
NaCl and contained varying amounts of standard NaOH. The
bottles were shaken for 72 hours at which time the pH had
reached a constant. The titration curve is shown in Figure 3.
In some initial experiments, attempts were made to estimate
the number of exchangeable sites. The fly ash was washed
repeatedly with NaCl (no acid wash) and rinsed free of NaCl.
245
-------
246
Excess Ba or Ca were added and the loss of Ba or Ca from the
aqueous phase determined. Minimum capacities of 0.22
meq/ 100 g for Ba and 2.3 meq 100 g for Ca were determined.
Subsequently it was found that the aqueous phase contained
0.15 meq K and 0.16 meq Mg per 100 g ash indicating that salt
and water washes do not remove all exchangeable cations.
Analytical Procedures. An Orion Research model 601 Digital
pH Meter was used for pH measurements. Conductivities were
determined using a Serfoss model RCM 15B1 Conductivity
Bridge. Atomic absorption analyses were carried out using a
Perkin Elmer model 303 Spectrophotometer and model HGA70
Graphite Cell Furnace.
For those samples of sufficient concentration analyses were
performed by direct aspiration of dilutions of Ba, Ca. K, Mg,
Mn, Na and some Cr, Fe and Zn samples. An air-acetylene
flame was used except in the case of Ba for which nitrous oxide-
acetylene was used. LaCI, was added to Ca and Mg samples to
suppress interferences. Some Cr, Fe and Zn samples were ana-
lyzed using the furnace. Linear least square fits of Absorbance
vs. Concentration of standards were generated and sample
concentrations determined using standard API. computer
programs.
Results
The pH of leachate in contact with samples of fly ash is listed
in Table I. A wide range of pH was observed, ranging from a low
of 4 (Sample 1) to a high of 11 (Ash A). Wide variability in fly
ash alkalinity has been noted by others.Sulphate content also
varies but does not correlate with pH. Increased sulfur oxide
content of ash would be expected to decrease the pH but
variable metal oxide content apparently mitigates this effect.
Table I: pH of Leachate and Soluble Sulphate Content8 of My
Ash Samples
similar behavior. Na and K concentrations remained relatively
constant while variation with time was observed in the concen-
tration ol the other cation.
Sample
1
?
3
5 6 ?
PH
4.06
4.16
4.29
4,;C
4,30 4.45 4,56
Sulphate®
15.6
14.2
16.
13.4
14.3 15.6 15-3
Sample
e
9
10
11
12 13
PH
5.53
5.83
6.34
7.08
8.80 9.40
Sulphate®
13.3
31.7
13-3
14,9
14.5 13.2
a
moole
sulphate per
100 g
ash
Extensive leaching studies were carried out on two fly ash
samples. The difference of ca 60 meq per 100 g in alkalinity
between these samples is illustrated in Figure I. The values
plotted represent the pH of the supernatant after five days oi
shaking to keep the fly ash suspended. It was found that much
longer time periods are required to attain equilibrium if the
solids are allowed to settle or are only occasionally stirred.
The solid points in Figure 1 represent samples that were
monitored over a five day period for pH, conductivity and
concentration ofCa, Cr, Fe, K, Mg, Na, andZn. The results for
Fly Ash B with no acid or base added are depicted in Figure 2.
The conductivity of the solution remained constant at 320
micromhos cm-1 indicating that the total electrolytic content of
the aqueous phase changed little with time. The concentration of
Na (120 ppm) and K (360 pptn) remain relatively constant. The
pH of the supernatant exhibits a slow drift from 4.0 to 6.7. The
concentrations of Ca (ca 600 ppm) and Mg(ca 40 ppm) change
moderately. However the concentrations of Cr, Fe, and Zn in
the leachate drop to near zero within five days. Leaching
experiments with Fly Ash B at high and low pH resulted in
cv, 0 20 40 60 80 100 120 MO
M«q OH" or HV IOO g Ash
Figure I: Alkalinity of Fly Ash Samples Used in Leaching
Studies.
0.5 2 8
Time (Hrs)
Figure 2: Dependence of Leachate Composition on Time.
Conductivity (micromhos cm-1 * 10-2): Ca, Fe, K., Na(ppm)-
Mg (ppm * 10); Zn (ppm * 100); Cr (ppb).
-------
247
Table 11 gives the maximum concentrations attained in the
leachates for both samples at various pH values. Table HI gives
the concentration at five days. Generally, all metal cations are
most soluble at low pH; calcium and magnesium concentrations
change little with time while chromium and zinc concentrations
decrease with time.
Table II: Maximum Concentration8 of Cations in Leachate
Over Five Days
Ash Sample leachate
Ca
cr
Fe
Mr
Zn
A acid
9200
9.7
300.0
400.0
4.1
A neutral
6600
.**7
2.0
230.0
2.5
A alkaline
130C
.55
.65
1.1
2.0
B acid
2900
6.6
710.0
140.0
5.6
B neutral
630
.24
78.0
0
0
5.4
B alkaline
1U0
.37
2.0
1.1
.70
a Concentration values
Multiply values by 2
solubllized oer
-------
248
ionic fraction Sm in the solution. The ionic fractions are defined
by'1
meq Mm+/g Ash
Zm = "meq (Mm+ + NaT) / g Ash
=
Normality of M
m+
m Total normality
Figure 4: Ion Exchange Isotherms for the M-Na-Fly Ash
Systems. Na+ is Leaving the Fly Ash.
I n a hypothetical system in which the ash shows no preference
for Mm+ over Na+ the equivalent ionic fractions in the ash are
the same as those in solution. The ion exchange isotherm would
be linear and form a diagonal in the diagram Zm versus Sm.
However, ion exchangers in general select one counter ion in
preference to the other. If the ion Mm+ is preferred the isotherm
is curved and lies above the diagonal; whereas ifNa+ is preferred
the isotherm lies below the diagonal.
The potassium isotherm of Figure 4 indicates that fly ash has a
slightly higher affinity for sodium over potassium. However the
fly ash has a high preference for Cr, Mn, and Zn over Na. The
fact that Zm reaches a maximum of 0.6 to 0.7 for all of the cations
measured indicates that a portion of the sites available to Na are
unavailable to the other cations. This may be due to relative size
of the ions or electroselectivity considerations.7
Table IV: Ion Exchange Capacity of Fly Ash
Cat Ion
Method
Capnclty
H+/Na+
titration
2-3
34/N»+
backtltratlon
3.0
CT
Isotherm
2.1
K
Isotherm
2.1
Mn
isotherm
1.9
Zn
Isotherm
1.8
Discussion
The results described here indicate several significant points.
Fly ash, upon exposure to water, releases soluble material a
portion of which then either precipitates or is reabsorbed via ion
exchange into the insoluble glass matrix of the ash. The loss of
soluble material from the liquid phase is minimized at low pH.
The exchange capacity of fly as'1, although small compared to
ion exchange resins, is significant if compared to the concentra-
tion of heavy metals initially solubili/.cd. [| jon affinities for
polyvalent ions other than chrome and zinc are also high, fly ash
may age so as to minimize toxic leachate.
The availability of several elements, including boron which is
a growth inhibitor at sufticient concentrations, has been shown
to decrease with age of ash." Acid treated fly ash causes
decreased symptoms of toxicity in plants.'' The efficacy of uses
of fly ash in the treatment of wastewater or in concrete might be
improved ilpre-aged by contact with water under controlled pH
conditions.
The dissolution and reabsorption phenomena demonstrated
here is consistent with others' observations. Natusch, et al. have
demonstrated that several elements are found in higher concen-
tration in the smaller ash particles.10 This is interpreted as
resulting from formation of the gloss matrix at high tempera-
tures in an atmosphere of smaller metallic particles or atoms
which are then preferentially adsorbed onto the smaller particles
in a coooler portion of the stack. Fisher, et al. describe
"plerospheres" that form while the glass is liquid followed by
cooling and the fixation of spherical particles.1 Since the
outermost surface of fly ash particles results from adsorption of
metal atoms or small particles at high temperatures from the gas
phase it would be expected that the surlace materials would
equilibrate upon exposure to a solvent.
REFERENCES
1. G. L. Fisher, D. P. Y. Chang and M. Brummer, "Fly Ash
Collected from Electrostatic Precipitators: Microcrystal-
line Structures and the Mystery of the Spheres," Science,
192, 553, 1976.
2. F. Helfferich, Ion Exchange, McGraw Hill, 1962.
3. M. G. Schnappinger, Jr., D. C. Martens and C. O. Plank,
"Zinc Availability as Influenced by Application of Fly Ash
to Soil," Environ Scie Techno!. 9, 258, 1975.
4. D. G. Shannon and L. O. Fine, "Cation Solubilities of
Lignite Fly Ashes," Environ Scie Technol. 8, 1026, 1974,
5. H. P. Gregor and J. I. Bergman, "Characterization of Ion
Exchange Resins. I Acidity and Number of Cation
Exchange Groups." J. Am. Chem. Sac., 70, 2370, 1948.
6. J. A. Marinsky, Ed., Ion Exchange, Vol. 2, p. 101, Marcel
Dekker, N.Y., 1969.
7. D. Reichenberg, "Ion Exchange Selectivity" in Ion
Exchange, Vol. I, J. A. Marinsky, Ed., Marcel Dekker,
N.Y., 1966.
8. L. H. Jones and A. V. Lewis, "Weathering of Fly Ash,"
Nature. 183, 404, 1960.
9. R. Holliday, D. R. Hodgson, W. N. Townsend and J. W.
Wood, "Plant Growth on Fly Ash," Nature, 181, 1079,
1958.
10. R. L. Davison, D. F. S. Natusch, and J. R.Wallace, "Trace
Elements in Fly Ash: Dependence of Concentration on
Particle Size," Environ Scie Technol, 13, 1107, 1974.
11. This research was supported by the U.S. Energy Research
and Development Administration under Contract No. E
(11 1) 2726- 2. We thank Mr. T. Reilly for assistance in the
leaching experiments and atomic absorption analyses.
-------
The Removal of 2,4,6-
Trinitrotoluene (TNT)
from Aqueous Solution
with Surfactants Y. Okamoto, E. J. Chou and J. Wang
Department of Chemistry
Polytechnic Institute of New York
Brooklyn, New York
and
M. Roth
Department of the Army
Dover, New Jersey
INTRODUCTION
The U.S. Army, ARRADCOM (Army Armament Research
and Development Command), has as its main mission, the de-
velopment and manufacture of munitions for the Armed Forces.
One of the serious pollution problems stemming from mission
fulfillment is wastewater emanating from plants engaged in not
only the manufacture but also the loading, assembling, and
packing (LAP) of TNT. It has been found at 2.5 ppm of TNT is
toxic and the aqueous solution is highly colored.
Extensive investigations on treatment of this waste water have
been conducted, including such processes as bacterial degradati-
on5,20 and adsorption on activated carbon8'19 and organic
resins21. At the present time, only the carbon adsorption
technique is utilized in several LAP plants. However, the carbon
adsorption technique suffers the disadvantage of carbon regen-
eration or disposal difficulty since it is hazardous and air
polluting to burn the TNT adsorbed onto the carbon. Thus, a
new process for the treatment of TNT waste water is being
continuously sought by military organizations.
We initially attempted to apply foam separation techniques to
remove dissolved TNT from aqueous solution. Foam may be
used to remove substances dissolved in a liquid by several
processes known collectively as foam separation13. The common
feature of all these processes is that separation is brought about
by virtue of differences in the surface activity of the dispersed
substances. These substances may be naturally surface active or
rendered surface active. The surface active components are
adsorbed and collected at the interface between gas and liquid
phases. Air or other gases bubbling through the liquid generate
gas-liquid interfaces and result in foaming which allows the
interfaces to be collected.
Foam separations have been investigated for years to remove
trace amount of metallic ions and certain organic compounds
such as phenol', enzymes18, naphthalene derivatives12, and alkyl
benzene sulfates10 from aqueous solution. Work conducted in
our laboratory for the past few years at the Polytechnic Institute
of New York under a grant from the Office of Water Research
and Technology, Department of the Interior, has shown that
metallic ions such as cadmium, mercury, nickel and copper were
removed almost quantitatively from aqueous solution using
chelating surfactants16'17'6, the surfactants chelated selectively
with metallic ions which were concentrated in the foam. The
foam was removed from the liquid and the surfactant was
regenerated and recycled by decomposition of the surfactant-
metal complex.
We applied the foam separation technique to the removal of
dissolved TNT from aqueous solution. The surfactant initially
used was 4-dodecyldiethylenetriamine. The results show that the
TNT was effectively removed by this technique from aqueous
solution. However, we have found that, under certain condi-
tions, the surfactant formed an insoluble complex with TNT in
aqueous solution and the complex was separated as a solid.
Thus, the solid formed could be separated by filtration. The ini-
tial concentration of TNT was in the range of 100-150 ppm. The
concentration of TNT in the filtrate was found to be only about
1 ppm. Since filtration is a simpler and more economical process
than foaming for separation of the dissolved TNT, we have
redirected our investigations on the removal of TNT from
aqueous solution with various surfactants containing amine
groups using filtration instead of foam separation.
Experimental
General Procedures
2,4,6-Trinitrotoluene was obtained from Fisher Scientific
Company and dissolved in water at 70-80°C. The concentration
of TNT used was in the range of 120-150 ppm.
The TNT solutions (1-3 2) containing various amounts of
surfactants were prepared and stirred magnetically. Samples
(50-150 ml) were periodically taken and.the solutions were
filtered through filter paper with the aid of celite or diatomite.
The TNT content in the filtrate was then determined.
Surfactants investigated were 4-dodecyldiethylenetriamine
obtained from Eastman Kodak Co. and fatty diamines such as
N-coco and N-tallow 1,3-diaminopropane which were obtained
from General Mills Chemicals Inc., and Armak Chemicals Di-
vision. These surfactants were used without purification.
Determination of TNT
2,4,6-Trinitrotoluene water solution has an absorption maxi-
mum at 230 m/u. with an extinction coefficient of about 2.2 *
10". However, in treatment of TNT waste, this absorption band
cannot be used to determine the concentration of TNT since the
solution contains some impurities or additives. Mudri15 had de-
veloped a simple procedure to determine the concentration of
TNT in waste water by adding NajSOj and NaOH to the
solution. This procedure was followed in the present investiga-
tion.
Results and Discussion
Removal of TNT Using 4-Dodecyldiethylenetriamine
Investigations were made on the removal of TNT from
aqueous solution using 4-dodecyldiethylenetriamine under
-------
250 Removal of TNT
various conditions. A typical procedure is as follows: solutions
(1)2) containing 1-29 , 2.58, 3.K7, 5.16 and 6.45 mole ratio of 4-
dodecyldiethylenetriamine to TNT were prepared. The solu-
tions were stirred at room temperature. Samples (60 ml) were
periodically taken and the results are summarized in Figure 1. It
was observed that the higher the concentrations of the surfac-
tant to TNT the faster the rate of TNT removal. For example
when the ratio was6.45, only 1 5% ()f the originalTNT was left in
solution after 2 hours stirring and only and 0.1% TNT left
after 4 and 6 hours, respectively.
Removal of TNT Using Fatty Diamines
Fatty diamines are commercially available in large quantities
and their prices are in the range of $0.70-1.50 per pound.
Therefore, investigations on the removal ofTNT usingN-coco-
and N-tallow propylenediamine were carried out under various
conditions. Typical results are shown in Figure 2.
Effects of Temperature
The effects of temperature on the removal of TNT were
investigated. We have found that faster removal ofTNT was
obtained at higher temperatures. Thus, the TNT in aqueous
solution was quantitatively removed at 80°C using only two
equivalent moles of the surfactant, N-tallow-1,3-
diaminopropane. Typical results are summarized in Figures 3
and 4.
TIME (Or)
Figure 1: Removal of TNT vs Time with Various Concentra-
tions of 4-dodecyldiethylenetriamine (the Numbers on This
Figure Are the Molar Ratio of Surfactant/TNT).
-------
Removal of TNT 251
8 10 12 14
TIME (hr)
18 20 22 24
Figure 3: Effect of Temperature on the Removal ofTNT with N-
tallow-l,3-diaminopropane. Molar Ratio ofTNT to Surfactant
is 1:1. Initial Concentration ofTNT is 140 ppm.
Removal of TNT Using
Amine Compounds in the
Presence of Surfactants
Removal of TNT from aqueous solutions was carried out by
adding a mixture of amine and surfactant to TNT water solution
at room temperature. Several solutions (12) containing 5.5 *
10-" M TNT (125 ppm), 6.0 * 10-" M N-methyl-1, 3-
diaminopropane (Jefferson Chemical Company, Inc.) and
various concentrations of a surfactant, hexadecyltrimethylam-
monium bromide, (Eastman Kodak Company) were prepared.
The removal ofTNT from the solutions was determined after 25
Table I: Removal ofTNT from Aqueous Solutions by Adding a
Mixture of N-methyl-1,3-diaminopropane and a Surfactant,
Hexadecyltrimethylammonium Bromide
Sample
No.
Cone.
in the Oriqinal
Solution, 10~4 M
TNT Removed
after 25 hr.%
Amine
Surfactant
1
5.5
6.0
2.0
84
2
5.5
6.0
4.0
97
3
5.5
6.0
5.0
100
4
5.5
6.0
6.0
9e
5
5.5
6.0
> 10.0
- 0
hours and the results are summarized in Table 1.
The results show that the TNT was removed quantitatively
when the concentrations of TNT, amine and surfactant were
almost equal. However, it was found that the degree of the
removal of TNT was very sensitive to the concentration of the
surfactant.
Analysis of the Reaction Product
The reaction of TNT with the amine group containing
surfactants yields a dark brown tar which is insoluble in water. It
was found that it can be dried and burned without explosion.
The solid was found to be non-explosive by impact sensitivity
tests. A typical elemental analysis of the solid isolated by the
reaction of TNT with 4-dedecyldiethylenetriamine, 1:3 molar
ratio, respectively is as follows:
C: 58.74% H: 6.64% and N: 20.29%.
According to this and IR spectra of the solid, it appears that the
brown solid is a mixed composition of TNT and the surfactant.
Discussion
TNT has a limited solubility (~5 * 10-4 M) in water at room
temperature and produces a highly colored solution when
reacted with strong bases11'2'4'14'3. The reaction has been
interpreted as due to the formation of an intermediate, 2,4,6-
trinitrobenzyl anion (TNT") which absorbs light in the visible
region (500-525 nm).
-------
252 Removal of TNT
oN
Q
LlI
>
O
IE
Ld
q:
100
90
80
70
60
50
40
30
20
10
v80°C
8 10 12 14 16 18 20 22 24
Figure 4: Effect of Temperature on the Removal of TNT with N-
talidw-l,3-diaminopropane. Molar ratio of TNT to surfactant is
1:2. Initial concentration of TNT is 140 ppm.
Time (hour)
TNT + B
NO„
BH
0
H O
©C-C-CH3
NO„
+ CH3-Jj!-CH
NO,
Base
<4r
NO,
NO,
TNT
When 2,4-dinitro and 2,4,6-trinitrotoluenes were reacted with
base, the anions initially produced were reacted with unreacted
nitro compounds to yield a complex.
The reaction rate was found to be very slow when simple amines
were reacted in aqueous solutions. The rate was almost identical
with surfactants containing amine groups when the concentra-
tion was below the critical micelle concentration (CMC).
However, the rate was found to be greatly increased (50-150
fold) above the CMC. The typical result is shown in Figure 5.
The enhancement in rate result is accounted for by the micellar
effect of the surfactant.7
The production of an intense coloration when a solution of m-
dinitrobenzene in acetone is treated with alkali was first noted
by Janovsky and Erb in 1886'1 and is now known as the
Janovsky reaction. The colored product obtained in the reaction
is recognized as the anion from the corresponding 2,4-
dinitrobenzyl ketone.
NO
Nrt 2,4-dinitro-
2 toluene
h joy*
I -CHp '
N02
CH,
2 Base .
!^"°2
2
N02-^-^NO2 2
The structures of these complexes were postulated by their
visible spectra.
-------
Removal of TNT 253
O
oc
£
O
OC
16 20 24
Surfactant x(IO~sM)
Figure 5: Relative Rate of the Formation of TNT- vs the
Concentrations of 4-dodecyldiethylenetriamine and 5-
methyldipropylenetriamine at 25°C in Aqueous Solutions.
Initial concentration of TNT was 2.5 * I0-4 M.
Thus, in the reaction of TNT with amine, the anion TNT" ini-
tially produced could react with unreacted TNT to form the
Janovsky complex. The complex was precipitated as a salt with
a protonated surfactant: (TNT - TNT)~ (surfactant H)+.
In the case of the reaction of TNT with a simple amine in the
presence of a cationic surfactant, we postulate the reactions to
be involved as follows:
TNT + Amine -> TNT" + Amine H+
TNT" + TNT -»• (TNT - TNT)"
(TNT - TNT) + cationic surfactant (R4N+Br") -*¦
(TNT - TNT)" R4N+ + Amine H+Br"
precipitated soluble in water
These hypotheses were suggested by very limited
experimental results and further investigation on these and
related systems are required to clarify the mechanisms of the
processes.
REFERENCES
1. Abe, T., Bull. Chem. Soc. Japan, 32, 229 (1959).
2. Bernasconi, C. F., J. Org. Chem., 36, 1671 (1971).
3. Blake, J. A., Evans, M. J. B. and Russel, K. E., Can. J.
Chem., 44, 119(1966).
4. Caldin, E. F. and Long, G., Prov. Roy. Soc., SerA, 226,263
(1955).
5. Channon, H. J., Mills, G. T. and Williams, R.T., Biochem.
J., 38 (1938).
6. Chou, E. J. and Okamoto, Y., J. Water Pollu. Contr. Fed.,
48 (12), 2747 (1976).
7. Cordes, E. H. and Dunlap, B. R., Accounts Chem. Res., 2,
329 (1969).
8. Coughlin, R. W., Ind. Eng. Chem., Res. Prod. Develop.,
50, 12(1969).
9. Ervin, E. and Danner, R. P., Separation Science 8 (2), 179
(1973).
10. Grieves, R. B. and Bhattacharyya, D., Separ. Sci., 1, 395
(1966).
11. Janovsky, J. V. and Erb, L„ Ber., 19, 2155 (1886).
12. Karger, B. L. and Robers, L. B., Anal. Chem., 33, 1165
(1961).
13. Lemlich, R., "Adsorptive Bubble Separation Technique,"
Academic Press, New York, (1972).
14. Miller, R. E. and Wynne-Jones, W. F. K., J. Chem. Soc.,
2375 (1959).
15. Mudri, S. S., Environ. Health, 10, 35 (1968).
16. Okamoto, Y. and Chou, E. J., Separ. Sci., 10, 781 (1975).
17. Okamoto, Y. and Chou, E. J., ibid., 11, 76 (1976).
18. Rubin, E. and Gaden, Jr., E. L., in "New Chemical
Engineering Techniques," Interscience, New York, 1962.
19. Schulte, G. R., M. S. Dissertation, Virginia Polytechnic
Institute and State University, Blacksburg, Virginia, 1972.
20. Tabak, H. H., Chambers, C. W. and Kabler, P. W., J.
Water Pollut. Cont. Fed., 35, 12 (1963).
21. Walsh, J. T., Chalk, R. C. and Merritt, Jr., C., Anal.
Chem., 45, 1215 (1973).
-------
An Industrial Residue
Management System
for Allegheny County,
Pennsylvania—Part I
INTRODUCTION
The Pittsburgh area is one of the heaviest concentrations of
major industry in the world. Twenty-seven maor industries are
located along the Ohio River between Pittsburgh and the Penn-
sylvania-Ohio line. The Monongahela River Basin contains the
largest concentration of steel-making capacity in the United
States. Pittsburgh is the nation's second largest "home-base" for
the largest U.S. corporations. About 1500 industries are located
in Allegheny County (Pittsburgh) and several hundred more are
in surrounding counties. The area possesses one of the largest
minable coal reserves in the U.S.—over 17 billion tons. Treat-
ment, handling and disposal of residues from existing and
planned industrial operations will be very costly and wasteful of
resources unless planned and managed.
Additionally, it is apparent that P.L. 92-500 will impose new
requirements through pretreatment requirements, best practica-
ble treatment, best available treatment and finally the zero
discharge goal. These legal requirements impose a future
generation potential for new residue quantities in the County.
The Department of Works of Allegheny County about two
years ago decided to examine the existing disposal schemes.
In the intervening two years a study co-sponsored by the U.S.
Environmental Protection Agency and the Allegheny County
Department of Works has been conducted on the current and
future generation rates and alternatives for treatment and
disposal of industrial residues within the county. Specific
objectives of the study included:
1. Classification of all industrial residues (wastewater treat-
ment, air pollution control, and process) into a minimal
number of categories that would be amenable to a certain
type of centralized treatment and disposal.
2. Determination of the total current and future volumes of
these residues as well as the spatial location throughout the
County.
3. A determination of alternatives and costs for collection and
transport of various residues recommended to be treated at a
centralized facility.
4. Identification of treatment and disposal concepts for
residues.
5. A development of management alternatives for implementa-
tion, financing and administration for industrial residue
management to meet environmental standards and the needs
of industry.
Donald Berman
Department of Works,
Allegheny County, Pennsylvania
Edward J. Martin
Environmental Quality Systems, Inc.
Rockville, Maryland
Joseph David, Jr.
Environmental Quality Systems, Inc.
Pittsburgh, Pennsylvania
This paper discusses the results of the classification and
quantification efforts and example collection and transport al-
ternatives are presented. A companion paper Part II in these
proceedings discusses Ihe treatment and disposal alternatives.
The feasibility of implementing an area-wide collection
treatment and disposal system for Allegheny County through
private and public means is being examined during 1977.
Current and Future Residue Amounts
Determination of Significant Sources of Residue
There are over 1350 individual establishments listed in the
1976 Pennsylvania Industrial Directory for Allegheny County,
most of which produce no significant amounts of residue. For
example, there are over 70 bakeries (SIC 2051) discharging
wastes to municipal sewers, with no pretreatment required
therefore generating no residues at the plant site. In order to
concentrate the study emphasis on generators of significant
amounts of residue, a priority system was developed. First, all
industries identified through federal and state discharge permits
were studied.
The priority system which eliminates remaining establish-
ments producing small amounts or no residue, is based on the
type, size, and location of the plant:
Type: each industrial classification (by a 4 digit Standard
Industrial Code (SIC)] was given a rating based on the potential
water quality impact of its waste discharge -A (serious), B
(moderate), C (slight). The more detrimental the waste dis-
charged by a plant, the more likely it is that it will provide
treatment and produce a significant residue.
Size: employ ment data is available for each establishment and
was used to estimate the size of the plant. Small plants which
produce insignificant residues were eliminated on this basis,
with cutoff points being lower for SIC's with a higher quality
impact potential. For example: industries outside of sewer ser-
vice areas were eliminated on the basis of:
SIC Class
A
B
C
With Employment
< 1
C10
<50
254
-------
Allegheny County—I 255
Location: a plant not possessing a discharge permit and
located within a sewer service area was assumed to discharge to
the corresponding municipal treatment plant. If the exact
location of the plant within the municipality was not known, it
was assumed to lie within a sewer service area if 75% of the
municipality is sewered. All industries for which pretreatment is
currently required or will be required were retained for analysis.
Other plants within sewer service areas were eliminated on the
basis of type and size as described, with higher cutoff points;
plants within the Allegheny County Sanitary Authority service
area have higher cutoff points due to the large dilution and
assimilation capacity of the system (average daily flow 190
MGD). These larger plants were retained in the study (although
they probably don't generate waste water treatment residues) to
determine if significant amounts of process or air pollution
control residues are generated.
In order to include all water treatment, air pollution control
and process residues generated within the County, the industries
isolated by the priority system were augmented by residue-
producing service SIC's such as power plants, municipal
wastewater treatment plants and water treatment plants as well
as mining-related activities such as coal preparation and acid
mine drainage treatment. There were 394 establishments con-
sidered in this study. Table I is a summary of the types of
facilities examined.
Data Gathering Methodology
The methodology developed for the determination of residue
generated by each industrial facility involved the ranking of the
following data sources:
1. Consultant telephone survey
2. Available residue data
3. Production data
4. Employment data
5. Influent and effluent data
For each establishment, if more than one data source existed,
the source with the highest priority was utilized. Telephone
survey information was by far the major data source, covering
all major industries within the county and representing over 99%
of the total county industrial wastewater flow.
Table I
SIC
Title
Number
20-39
Manufacturing
283
49
Public Utilities
72
70-79
Services
14
40-47
Transportation
12
50-51
Wholesale Trade
8
12-15
Mining
5
12-79
Total
394
About one-third of the total number of industries provided
data in the telephone survey. Residue data were available for
about one-third, including municipal water and wastewater
treatment plants, and power plants. For about 30%, production
and employee data were used to estimate residue values. For a
small fraction of the total, wastewater data were used,
used.
Following is a description of each type of data source and the
methodology used for the determination of residue generation.
1. Telephone Survey
Following a review of all data obtainable at federal, state and
local levels, it was decided to conduct a telephone survey to
augment the incomplete data base and gain actual, current
information on residue generation. Originally, the best method
to obtain residue amounts was thought to be through predic-
tions based on wastewater influent and effluent concentrations.
This methodology was abandoned in favor of actual industry
contact for the following reasons:
a. Amounts of process and dry air pollution control
residues could not be determined. Since these residues present
similar treatment and disposal problems to water pollution
control residues, the scope of the study was expanded for their
inclusion.
b. Much of the wastewater data included in NPDES
applications is out of date and incomplete due to the rapidly
changing production rates and methods of many industries.
c. To characterize wet volumes of residue, needed for
transport requirement estimate and treatment system design, %
solids and % increased quantities from additional treatment
would have to be estimated, introducing sources of error.
On the basis of the consultant's experience with data
collection techniques, it was decided to conduct a telephone
survey. All major industries in the County with greater than 500
employees and wastewater flow greater than 0.10 MGD were
contacted. In addition, the largest facilities in the major
Allegheny County industrial classifications were contacted to
insure a representative survey of all types of industrial activity.
The 103 industries in the survey were contacted first by
introductory letter, then by telephone, and asked to provide
information on all present and future residue generation,
residue characteristics, wastewater discharges and treatment
provided, employment, production, and current residue man-
agement practices. Response to the survey was excellent with
over 97% of the industries contacted providing the requested
information.
2. Available Residue Data
Limited amounts of actual industrial residue generation data
were obtained from files of the Pennsylvania Department of
Environmental Resources (DER):
a. Solid Waste Permit Applications
b. Industrial Solid Wastes Survey (1968)
c. NPDES and DER Discharge Permits
Municipal waste water treatment and water treatment facilities
residue data was available in the Pennsylvania Comprehensive
Water Quality Management Plant (COWAMP). Current
residue data were available from the Allegheny County Health
Department for electric generating and steam supply facilities.
3. Production Data
For industries for which production data were available,
residue generation was calculated based on production.
Production information was available from federal and state
discharge permits and other sources. Values were developed for
use in the prediction of residue amounts based on production.
The values were developed from telephone survey information,
actual residue data, EPA Development Documents and a
general literature review.
4. Employment Data
Employment data were available for most of the remaining
industries (the Pennsylvania Industrial Directory). A table was
developed listing production per employee values based on the
telephone survey, U.S. EPA Development Documents,
COWAMP data, Allegheny County Sanitary Authority
(ALCOSAN) data, and Pennsylvania Department of Com-
merce data. This table was used to generate a production figure
for certain remaining industries; residue generation is calculated
on the basis of these values as in 3 above.
5. Influent/Effluent Data
If pollutant concentrations for the raw wastewater and
treated effluent of the industry were known, residue generated
could have been calculated on a mass balance basis. Percent
-------
256 Allegheny County-
solids and treatment chemical additions based on literature-
reported values for specific treatment processes would result in
residue estimates.
When only effluent data were available, residue generated
could have be based on predicted raw wastewater pollutant
concentrations obtained from U.S. EPA Development Docu-
ments for Effluent Guidelines or the technical literature.
This approach for estimating residue quantities was used as a
last resort when production or employee data were not
available.
6. Future Residue Amounts
Prediction of future residue amounts generated within the
County is dependent on many variables:
—The rate of industrial and population growth
—Development of improved manufacturing technology
resulting in process modifications which reduce waste genera-
tion
— Development of reuse/recycle technology resulting in the
economic utilization of present waste residues as valuable raw
materials. This latter will be directly dependent on availability of
domestic and foreign raw materials and alleviation of tax
disincentives on reused materials.
—Extent of the enforcement and enactment of air and water
pollution control laws. This could both reduce residue volumes
through the closing of industries which could not economically
comply and increase residues through higher pollutant removal
requirements.
Industries contacted in the telephone survey were asked for
future residue predictions based on production changes and
future air and water pollution control requirements. For the
remaining facilities, increases in water pollution control residues
were predicted on the basis of the EPA Best Available Technol-
ogy Economically Achievable guidelines scheduled for imple-
mentation by 1983. Often 1983 residue generation is not
significantly greater than 1977 as the bulk of the pollutant load is
removed by the BPTCA controls already in place.
Residue sources were spatially located within the County in
order to develop hauling requirements.
Results
Residue Classification
The industrial residue classification system, consisting of six
major types divided into 45 subcategories, is based on a
knowledge of transportation, storage, treatment and ultimate
disposal requirements of the residue groups. Residues that could
be mixed for transport and which are amenable to similar
treatment processes are assigned to the same subcategory. When
distinct treatment and disposal alternatives exist for similar
wastes, they are maintained in separate subcategories. Recycle
and reclamation alternatives to be considered may require strict
segregation of wastes, resulting in a greater number 0f
categories.
Residue Amounts
Residue amounts obtained through the telephone survey and
other data sources were entered for each industry in a
computerized data base. Amounts are entered as generated
(wet) for calculations of transport and treatment/disposal
capacity requirements- Information entered in the data base
include industry I.D. number, municipality, *'P c°de area,
discharge point, employment, production amounts, and 1977
and 1983 residue generated by individual industry. Residue
totals by collection district and the County as a whole are
maintained. This information Can easily be kept current with the
additions of new industry and residue information in the future.
Total County residue. gener^on jn all ciassifications is pre-
sented in Table II.
Table II: Allegheny County Daily Residue Generation (wet
basis)
~T977~
A- OUj. Maitci. (tot?!'*)
WWT sludge
Machinery lubricants
Hydraulic, oil
Emulsions
Animal oils A
Cutting oil
Tank bottoms
Crankcase oil*
fats
B. Waste Solvents .(totab)
Paint manufacture
Resin manufacture
Metal cleaninq
Printing, Htho.
C. Organises _(to_Ul5)~ -
1. Food processing
2. Phamaceutlcals
3. Coal fines
4. Municipal WWT
b. Cleaning emulsions
34
3
0
5
6
1?
lb
1
5
0
4
43
9
D. Heayx total-Contain Ing Wastes( totals
Iron hydroxide
2. Metal finishing
3. Spent pickle llquor-H^SO/j
4. Spent pickle 1iquor-HCl
5. Ai r pol. control dusts
6. Scrubber sludges
7. Scale
8. Foundry sand & metalllcs
9. Other
t• LnorfLarucs (t^ -
Foundry sand
Iron slag
Steel sUq
F6D sludge
Cullet, glass manufacture
Cement dusts
Water treatment
Fly ash
Othei
Hazardous Wastes J totals)_
1. Acids
2. Caustics
3. Organic^
4. Waste paint, dye
5. Inorganics
6. Coke production
7. Pitch sand , tar
County Total
4
16
13
0
4
11
21
24
2 5
10
7
1
3
5
28
0
6
5
15
3
2
2
]983
kkg
find.
kkg
9B_ _
60
105
2.3
34
2.3
0.20
3
0.20
0.0
0
0.0
4.0
5
4.0
1.5
5
1.5
45
12
51
2.4
1
3.5
43
*
43
VL
22
11
8.9
15
8.9
0.69
1
0.69
0.90
5
0.90
0.17
\
O.U
1180
65
1210
16
5
16
0.0
0
0.0
S20
4
520
640
43
670
3.8
10
6.5
2210
100
3520
1100
5
2140
91
16
92
420
13
420
0.0
0
0.0
61
4
4
510
11
520
9.7
22
279
19
24
20
1.5
5
...
11460
90
10850
96
25
96
4300
9
3400
3200
7
2200
510
3
1700
4.
2 4
5.6
100
6
100
1500
28
1600
1750
8
1750
99
37
140
0.
0 0
0.0
9.
3 6
9.3
22
5
22
5
6 15
5.6
4
0 3
4.0
38
3
85
20
2
20
15,060
15,840
~Based on dally accumulations at an estimated 600 service stations 1n the county.
Ten of the 45 sub-classifications account for 95% of the total
current residue generated as shown in Figure I. Iron and steel
slags account for approximately 50% of total current residue,
but will decrease to 35% by 1983.
Of the total of approximately 15,000 metric tons of residue
currently generated in the County daily, 15.5% (about 2300 kkg)
can be classified as hazardous wastes; this will increase to about
3700 metric tons or 23% of the total by 1983. Hazardous wastes
include all sub-classifications in the waste solvent, heavy-metal
containing and "other hazardous" wastes categories. Four of the
20 hazardous waste classifications account for 91% of the daily
total, iron hydroxide sludge from pickling wastewater (47%),
scrubber sludges from steel making furnaces (22%), spent
sulfuric acid pickle liquor (18%), and metal finishing sludges
(4%). Major hazardous waste categories are graphically
depicted in Figure 2.
As seen in Figure 3, steel mills (SIC 3312)arebyfarthemajor
source of hazardous wastes, generating approximately 2220
metric tons per day; over 95% of the County total. The
-------
Allegheny County—I 257
24% (77)
2T% (83)
21% (77)
1977 (Total 15,060 kkg/day - 90%)
1983
(Total 15,840 kkg/day - 94%)
\4\ (S3)
74% (S3)
U% (77)
m 183)
7 7% (83)
10% (83)
10X (77)
7% (77)
4% (83)
3% (83)
4S (77) .
31 (S3)
31 (£3)
3% (77)
3% (77)
3% (77)
3% (77)
Figure I: Major Residue Classifications
remaining 5% is generated mainly by industries in the paint and
industrial coating (2.5%), foundry (<1%), and non-ferrous
metals (about 1%) classifications.
Integrated steel mills are also the leading generator of all
residues, (see Figure 4) accounting for over 65% of total County
residue or 9820 metric tons per day. A decrease in slag produc-
tion due to process changes by a major steel mill will offset
increased wastewater treatment residues, resulting in a decrease
to 59% and 9270 metric tons by 1983. Power generation,
wastewater treatment and water treatment functions generate
significant quantities of residues.
Current Reclamation, Treatment and Disposal
Practices
Several large disposal sites within the 'County currently
handle the major fraction of the major non-hazardous residues
such as slag, flue gas desulfurization (FGD) sludges and fly ash.
Hazardous wastes are disposed of at two major company-owned
sites within the County and by a number of private contract
haulers utilizing out-of-County treatment and disposal sites in
Beaver, Westmoreland and Washington Counties and as far
away as Michigan, New York and New Jersey. Transportation
costs thus become an important factor adding to high disposal
costs for some hazardous waste classifications. In addition,
large amounts of potentially recyclable materials are currently
being landfilled and stockpiled (e.g., slag). Future reclamation
efforts could significantly reduce waste residue generation
totals, disposal costs and current inventories of materials.
Current Recycle and Reclamation of Residues
Residues that are recycled on the premises or within the same
company that generates them do not appear in the County
residue totals. The following residues have significant in-plant
recycle and reclamation rates:
Blast furnace dust—all flue fines collected both from dust
catchers and wet scrubber systems are currently recycled
through sintering facilities. Flue fines from ferromanganese
blast furnaces are not as amenable to recycle but are currently
not being generated due to the shut down of these operations.
Mill scale—virtually all mill scale currently collected in scale
pits treating effluents from hot and cold rolling mills is recycled
to the blast furnaces via sinter plants. The metal value may be
reclaimable from residues generated in th? future by treatment
of mill scale effluent.
Coke breeze—fine coke particles which settle out from coke
quench water can amount to up to 1.5% of total coke produc-
tion. All bf this residue is reused, primarily as feed to the sinter
plant. As air pollution control equipment is installed on
charging and pushing operations, similar residues will be
generated and will be presumably recycled to the same extent.
Sinter dust—the dust generated by sintering operations is
collected by electrostatic precipitators and baghouses; addi-
tional residues may be generated through sedimentation from
scrubbing and quenching effluents. All of this collected residue
is recycled directly to the head of the plant.
Kiln dust—up to 80% of all kiln dust generated in cement
manufacturing facilities collected by air pollution control
equipment is recycled directly to the kiln. High alkali dusts are
undesirable as raw charge and are landfilled; reclamation of this
fraction of the kiln dust through leaching of alkalai materials is
currently not practiced within the County.
Coal fines—one of the five major coal preparation plants
operating within the County currently reclaims the coal value
from the black slurry effluent from the washing and upgrading
operations. Settling pits for the other plants can be considered as
possible stockpiles for future reclamation efforts when it
becomes economically attractive.
In addition to on-site reclamation of residues by generating
-------
258 Allegheny County—I
5St (S3)
1
47% (77
1977 (total 2,320 kkg/day - 99.2*)
19S3 [Total 3,670 kkg/day - 99%)
22% (77)
Ml (S3)
18% (77)
HI (S3)
t% (S3)
4% (77)
31 (S3)
3% (77) , 31 f77l
n 1831
n (S3)
Figure 2: Major Hazardous Waste Classifications
n (S3)
JS (S3)
industries, several private firms are currently involved with
recycling significant amounts of residues. Private reclamation
firms are nportant in the handling of the following residue
classifications:
Blast furnace slag—the Duquesne Slag Company operates
iron slag processing plants adjacent to major steel mills in
Pittsburgh, Duquesne and McKeesport. Molten slag from the
blast furnaces is cooled in open pits, quenched with water,
crushed, processed for iron reclamation, and then sold to
construction and road-building firms for use in cement
concrete, asphaltic concrete, masonry units and various other
construction materials. The Phillips Slag Company in Stowe
Township similarly processes slag for a mill on Neville Island.
The slag companies pay royalties by the ton to the mills for iron
slag contracts. Demand for processed iron slag is currently
greater than supply prompting current reclamation efforts on
old slag piles. A decrease in the construction of interstate
highways in the near future could reduce current demand levels.
Specialty Steel Wastes (flue dust, mill scale)—The Interna-
tional Metals Reclamation Company (INMETCO), a subsid-
iary of International Nickel Inc., is currently constructing a
reclamation plant in Ellwood City, in adjacent Beaver County
scheduled to begin operations by mid-1978. The plant will
process more than 40,000 tons per year of stainless and alloy
steel manufacturing residues primarily generated in the Pitts-
burgh Metropolitan Area. Three Allegheny County mills will
send wastes there that are currently being landfilled. Flue dust,
mill scale and grinding swarf, difficult to recycle because of high
zinc and lead content, will be converted via a proprietary
smelting process to a stainless steel remelt alloy. Specialty steel
pickling residues will not be handled by the current facility, but
research is being conducted on possible reclamation processes
which could be included in future plant expansion plans.
Waste oil—several oil reprocessing firms handle part of the
oily wastes generated by large steel rolling operations and metal
fabrication plants within the County, but the majority of these
wastes are still landfilled. These firms also reprocess most of the
waste lubricants generated by other sources such as newspaper
printing, glass manufacturing and service stations. Charges to
the generating facilities are often based on moisture or other
contaminant content of the waste oil.
Waste foundry sand—approximately 20% of the waste
foundry sand generated within the County is cleaned and
reprocessed for reuse. Artisand, Inc. in nearby Westmoreland
County and Allegheny Sands, Inc. of Pittsburgh pay royalties
and transportation costs f°r sanc® fr°m tw0 major foundries
-------
Allegheny County—I 259
10% (S3)
65% (77)
1977 (Total 2,320 kkg/day - 98.4%)
1983 [Total 3,670 kkg/day - 100%)
24% (77)
75% (S3)
S% (S3)
3* (M) 3% m)
3*(77)
(M)
21iZZLo.8%(77) 0.6%(77) 0.6%(77)
I
I
o.nm m*imj o.4us3\
steel are handled by two out-of-state chemical reclamation
firms. Erie Disposal of Cleveland, Ohio accepts the detinning
wastes for the reclamation of caustic chemicals, charging for
transportation only. The tank cleaning wastes are processed by
Chem-Trol Pollution Services, Inc., near Buffalo, New York, a
firm that reclaims chemical values from many types of
hazardous wastes including pickle liquors, plating solutions,
solvents, mercury containing sludges and other waste inorganic
and organic chemicals. Seven basic unit processes are utilized at
the plant, either separately or in combination, for reclamation
and secure disposal of hazardous wastes: filtration (vacuum,
pressure), thermal oxidation, neutralization, distillation, chemi-
cal disposal, physical separation (centrifugation, counter-
current extraction) and scientific landfill. Chemical wastes are
Figure 3: Hazardous Waste Generation by Standard Industrial Code
which they then clean, reclaim metallic values and resell to the
mills.
Spent solvents—several private facilities outside of the
County handle waste solvents, often on a contract basis. Most of
these private regeneration plants are located out-of-state,
adding more transportation costs to the cost of disposal which is
the highest per unit volume of any of the residue classifications.
A manufacturer of printing ink within the County currently
regenerates its own spent solvents, and a major manufacturer of
paints and industrial coating is currently installing a solvent
regeneration unit.
Caustic chemical wastes—hazardous caustic wastes gener-
ated by an industrial coating manufacturer in tank cleaning
operations and by a scrap processing plant in the detinning of
-------
260 Allegheny County—I
65% (77) .
591
(S3)
1977 (99.7%)
;9*3 (300
221 (S3)
14% (77)
1 10% (77)
101 (S3)
4% (77)
4t (S3) |
3% (77)
3% I S3)
Figure 4: Residue Generation by Standard Industrial Code
.lalyzed in the laboratory for the determination of disposal
charges and treatment methods. Closed storage tanks and
polyethylene lined lagoons are utilized with storage capacities of
2 million and 6 millions gallons respectively. The plant generates
no wastewater effluents.
Current Treatment and Disposal Practices
For the remaining residue classifications generated within the
County, reclamation and recycling is currently not practiced.
These residues are either disposed of on-site by the generating
industry or removed from the sites for a fee by contract haulers
and disposed of at privately-owned landfills. Eight major on-site
and company-owned disposal areas are operated in the County,
all disposing to lagoons or landfills.
Seventeen private contract haulers and disposal areas were
identified that handle residues generated within the County. All
provide lagoons or landfills. Two provide neutralization ser-
vices, and one provides incineration.
|0.7% (77)
0.6% H5\
3% (77)
Steel Furnace Slag—Slag from steelmaking and foundry
operations is not as amenable to use in the construction industry
as blast furnace slag due to its physical characteristics. Small
amounts are utilized in sinter plants and as construction fill after
aging, but the major part must be landfilled.
The Duquesne Slag Company handles disposal of these
residues for the two major steel companies, the major disposal
site being Nine Mile Dump in the City of Pittsburgh. Other
major disposal sites are located in West Mifflin near the
Allegheny County Airport, and in Penn Hills along Thompson
Creek. Slag generated at smaller specialty steel makers and
foundries is collected and disposed of by contract haulersat sev-
eral landfills throughout the County.
Fly Ash and Flue Gas Desulfurization (FGD) Sludge—These
residues are often combined for disposal at the Phillips Generat-
ing Station, although collected separately. The residues are not
considered hazardous but present a disposal problem and
-------
Allegheny County—I 261
expense due to their magnitude. FGD sludges are difficult to
dewater, but recent advances in stabilization technology have
resulted in the development of fixation agents which solidify the
sludge in a relatively short time. At the Phillips Station, the
FGD sludge is pumped to curing ponds where the fixation
chemicals are added; the hardened sludge is excavated, mixed
with fly ash, and trucked to a nearby landfill for ultimate
disposal. At the Colfax Station in Cheswick, the dry fly ash is
slurred and pumped to an abandoned mine for disposal.
Iron Hydroxide Sludge—U.S. Steel operates the Brown Dispo-
sal site for neutralized pickle liquor at its slag dumping area in
West M ifflin. The spent sulfuric acid pickle liquor is neutralized
at the plant and then transported to the disposal site where it is
deposited in large lagoons dug into the slag piles. The thin sludge
(2% solids) dewaters through evaporation and percolation of
water through the slag piles. The site has adequate capacity to
handle increased residues generated from acid rinse water
neutralization and future spent pickle liquor neutralization
sludges.
Allegheny Ludlum Steel landfills acid rinse water neutraliza-
tion sludges dewatered to 50% solids at its Brackenridge plant.
Capacity of the site, consisting of slag dikes built into the
Allegheny River has been reached, and a new on-site landfill is
under construction.
Spent Pickle Liquor— For the other major pickling operations
within the County, untreated spent pickle liquor is collected and
disposed of in surrounding counties by contract haulers. Mill
Services, Inc. operates two major treatment and disposal sites
for spent pickle liquor and other hazardous chemical wastes in
New Stanton, Westmoreland County and Blager, Washington
County. The acid wastes are neutralized in polyethylene lined
lagoons with effluents receiving further physical treatment
before discharge. The sites have a disposal capacity of 15-20
years, handling 3 to 5 million gallons of waste per month.
Industrial Wastes, Inc. (LENCO) of Darlington, Beaver
County, the other major hauler for spent pickle liquor, provides
lime neutralization at its Folston site which has a disposal
capacity of 10-20 years, at current rates.
Other Hazardous Wastes—The United States Utilities Service
site in Monroeville and Canistrale Landfill in Monessen, Wash-
ington County, are not currently accepting Allegheny County
pickle liquor but do dispose of other hazardous chemical wastes.
Canistrale utilizes fly ash lined lagoons with chemical leachate
treatment for disposal of coke production residues and other
hazardous wastes. The lagoons are revegetated when full; the
site has a 10-15 year capacity. The Kelley Run Landfill in
Forward Township disposes of coke production sludges, waste
oil and foundry wastes in fly ash lined lagoons. Browning Ferris,
Inc. operates a chemical landfill near Imperial and a hazardous
waste incinerator in East Liverpool, Ohio. The Imperial site de-
posits chemical plant and foundry wastes in fly ash lined
lagoons. Spent solvents and chemical wastes from several
County industries are incinerated and treated at the East
Liverpool plant with residuals deposited in a chemical landfill
on the site. Hazardous materials have been accepted at the C. D.
Cotrell Landfill in Westmoreland County, W. D. Mays Landfill
in Stowe Township and Mazzaro Landfill near Imperial; the
extent of current disposal of hazardous wastes at these sites is
not accurately known.
Major on-site or company-owned disposal areas for hazard-
ous wastes are operated by U.S. Steel and Allegheny Ludlum.
The U.S. Steel Taylor Disposal Site is utilized for flue fine
residues dewatered to 80% solids from open hearth, basic
oxygen and electric furnaces, as well as some blast furnace slag
and fly ash. Waste oil from rolling operations is mixed with the
neutralized pickle liquor at the Brown Disposal Site. Allegheny
Ludlum currently disposes of mill scale (15% solids) and steel
dusts (50% solids) on-site; much of this material will be handled
by a company waste reclamation facility in the future.
Residue Disposal Costs
Current residue treatment and disposal costs are presented in
Table 111, broken down by major residue classifications. Unit
disposal costs are based on information supplied by industries
and disposal firms contacted in the telephone survey. Blast
furnace slag, which is currently sold to reclamation firms, is not
included in the table. The total annual disposal cost of approxi-
mately $20 million includes charges by reclamation firms as well
as disposal firms, and estimates for transportation and on-site
disposal costs for construction and land.
Several large, non-hazardous residue classifications, primar-
ily generated by several major establishments are currently
being handled in an efficient manner at County disposal sites
with sufficient capacity for continued operation in the foresee-
able future. These classifications include iron and steel slag,
steelmaking, air pollution control residues, flue gas desulfuriza-
tion sludges, cement dust, water treatment sludges, fly ash and
coal fines. These residues are generally disposed of close to the
generating industry disposal operations through enforcement of
new legislation and increased operating expenses for others.
Transportation costs for some wastes to surrounding County
and out-of-state disposal locations are significant and, being
energy intensive, will increase. The establishment of a central-
ized treatment and disposal facility for these types of wastes
could, therefore, reduce future costs. The following types of
residues may be included;
1) Spent pickle liquor and iron hydroxide sludges—
Approximately 520,000 metric tons of these residues are
generated annually by 17 sulfuric acid pickling operations.
Based on industry-wide averages, this represents a total of
42,000 metric tons of iron and 42,000 metric tons of free acid
annually deposited in landfills in the form of non-recoverable
iron hydroxide sludge. No acid regeneration or iron recovery
processes are currently in operation or planned at any of the
mills. Future treatment and disposal of the materials in this
manner will increase in cost with implementation of the
provisions of the hazardous wastes section of the Resource
Recovery Act of 1976.
2) Metal finishing wastes—Recovery of metallic values from
spent plating solutions could be pursued to reclaim resource
value and to reduce transportation costs. Disposal sites for these
residues can be considered as storage or stockpile areas for
materials that could be recycled in the future with the advent of
improved technology. For example, research on extracting
metallic values from waste steelmaking dust has been a high
priority in the industry for years and several processes are in
final stages of development. When implementation of reclama-
tion technology becomes economically feasible, current residue
quantities will be recycled to the sinter plant by the generating
steel mill and large stockpiles at landfills could be reclaimed.
Similar residues from smaller generators such as iron and steel
foundries could be accepted by the larger mills resulting in
reduced disposal requirements and costs, as well as an increased
supply of inexpensive raw materials.
Hazardous residues that are generated by a large nurrtber of
smaller industries that are currently disposed of at many
locations in and outside the County could be the primary
concern of an area-wide management system. Capital and
operating costs to process wastes at individual establishments
may be prohibitive. The approximately 33,000 metric tons
annually of dilute wastes produced by 16 finishing operations
within the County could present an opportunity for a reclama-
tion process if wastes are transported to a centralized facility.
-------
262 Allegheny County—1
Table III: Current Residue Treatment and Disposal Costs
Annual Amount
Unit Disposal
Total Annual
CI ass
Type
(kkg)
Cost (S)
Cost ($)
A1-A9
Oily wastes
35,800
.00-.06/gal
284,000
B1-B9
Spent solvents
4,020
.08-.25/gal
175,000
C1.C5
Organi cs
7,300
6.00/T
48,000
e3
Coal fines
281,000
1.00/T
310,000
C4
Mun. WWT sludge
dewatering
233,600
3.00/T
773,000
incineration
175,200
11.50/T
2,220,000
1andfi11
83,950
6.00/T
555,000
D1
Iron hydroxide sludge
405,200
.02/gal
2,140,000
D2,D3
Metal finishing residues, spent
150,000
.02-.06/gal
1,980,000
pickle liquor
D4-D9
Ai r pol. resid., scale
219,000
3.00/T
724,000
El
Foundry sand
28,200
3.00/T
93,000
E2,E3
Slag
1,273,000
3.00/T
4,210,000
E4
FGD sludge
186,200
6.00/T
1,230,000
E5.E6
Cement dust, cullett
38,000
3.00/T
126,000
E7
Water treatment sludge
547,500
3.00/T
1,810,000
E8
Ash
638,800
3.00/T
2,110,000
F1-F5
Hazardous chemical wastes
15,000
.08-. 16/gal
475,000
F6-F7
Coke product residues
21,200
6.00/T
140.000
TOTALS
4,343,000
19,403,000
3) Spent solvents—Disposal costs for contaminated solvents
utilized in paint and coating tank cleaning and metal degreasing
are the highest of any classification. Regeneration of these
materials requires a large volume to be economically feasible
and is, therefore, not practiced by individual generators.
Disposal areas must take extensive precautions to prevent
discharge to the environment of materials which are often highly
toxic in small quantities such as chlorinated hydrocarbons and
various types of heavy metals. Centralized recovery or secure
disposal of these materials would, therefore, be highly desirable.
4) Waste oil—Approximately 36,000 metric tons of waste oil
is generated annually by 60 industries (primarily cutting oil from
rolling mills) and an estimated 600 service stations. Some of this
oil is re-refined by several private firms with charges ranging
from 0 to 3 cents per gallon based on moisture content of the
wastes. Reclamation efforts will probably increase resulting in
less of these materials deposited in area landfills. A significantly
greater recycle rate for oily wastes could be accomplished
through an effective management system, resulting in lower
disposal costs and less waste of resources.
5) Hazardous wastes—About 34,000 metric tons of other
hazardous wastes primarily generated in coke production and
organic chemical manufacturing are deposited in many landfills
spread over surrdunding counties and other states each year.
Costs for toxic chemicals disposal range from 8 to 16 cents per
gallon. Increased treatment of acid and plating rinse waters will
substantially increase total hazardous waste generation in the
near future. The establishment of a centralized scientific landfill
would reduce future disposal costs and adverse environmental
impact of these wastes.
6) Foundry sand—Currently a small percentage of waste
foundry sand is reclaimed for reuse in the mills with most going
to area landfills. Expansion of reclamation capacity for these
wastes could be incorporated in a management plan.
Collection and Transport of Residues
Current Transportation Practices
Transportation of residues within the county is currently the
responsibility of the individual contract hauling and disposal
firm handling the waste. Disposal charges include cost of
transport to the site as well as treatment and disposal cost. Some
transport on-site disposal areas of large volumes generated by a
single industry (such as slag) is done by rail with the remainder
carried by company-owned trucks. In order to reduce costs
individual companies must provide enough storage capacity to
fill large capacity trucks. No temporary storage of wastes or
barging is practiced.
Transport Alternatives
In a county-wide management system, several alternatives
exist for moving wastes to a centralized treatment and disposal
site.
No operator transport responsibility individual companies
using the central facility would be responsible for gettingwastes
there. This would not be responsive to the needs of small firms
which could not provide their own trucks. Equipment would lay
idle much of the time, thus increasing unit costs.
Regional collection stations—This method has been success-
fully used for a centralized industrial waste treatment system in
Denmark.* Wastes are delivered by individual generators to 25
collection points throughout the nation; from there they are de-
livered by rail to the plant. Due to the smaller land area and
concentration of wastes in sections of Allegheny County, this
* P. Henriksen, "One Private Plant Treats Oil, Chemical Residues in
Denmark." in Solid Wastes Management Magazine. May 1974.
-------
Allegheny County—I 263
type of system does not appear economically feasible for a
County plan. Transport of wastes to collection points would still
pose a burden for small generators.
Collection by the county with intermediate storage -Use of
intermediate storage facilities (transfer stations) has been
proven an economical alternative in municipal solid waste
collection. Small capacity collection vehicles deliver wastes to
regional transfer stations from which they are delivered to the
main processing point by more economic, large capacity long
haul trailers. Several factors make this type of system infeasible
for an industrial residue collection system.
Strict segregation of some hazardous type wastes must be
employed to prevent accidental mixing of incompatable chemi-
cals.
Additional handling increases the risk of spills and environmen-
tal contamination.
—Large capacity collection vehicles may be utilized directly
for pickups of many major residue generating industries thus
eliminating the need for intermediate storage.
Barging to centralized treatment area—this alternative is a
possibility for major residue generators located on the three
major rivers if a centralized processing site near a river was
available. Standard barge sizes of 840,000 gallons (3200 kkg)
and 1,750,000 gallons (6600 kkg) would be filled with any
frequency by only the very large sources (e.g., steel mills) in the
county. Relatively short barging distances within the county
makes this type of transport uneconomical if extra transfer of
wastes is required.
If the preceeding alternatives are rejected, direct pickup and
delivery to a centralized disposal facility by operator-owned or
leased trucks is the best transport alternative. To prevent mixing
of wastes of widely varying compositions and in order to lower
unit costs through the use of large capacity vehicles, individual
residue generators should provide adequate storage capacity to
result in a full load at each pickup.
Dewatering Considerations
For sludges with a high moisture content, such as iron
hydroxides and metal finishing wastes, an analysis must be per-
formed by each individual generator to determine the most eco-
nomic rate of dewatering; i.e., the point at which the cost of
further dewatering exceeds the transport cost of the water
content. Consideration must also be given, on a residue
classification basis, to dewatering at the centralized facility to
gain economy-of-scale benefits on needed equipment. This
would apply in cases where dewatering results in more econom-
ic disposal, such as in a scientific landfill.
Table IV: Transport Variables
10. West: 20 kkg
7. East: 22 kkg
1. South Central:
25 kkg
9. South: 1160 kkg
Southeast:
192 kkg
Parameter
Good
CAsL
Averaqe
Worst '
Truck lease charge ($ per year)
8200
8700
9200
Lease cost/mile ($)
.11
.12
.13
Overhead factor
.25
.50
1.00
Circuitry factor (region)*
1.06
1.3
1.4
Truck capacity (liters)
22,700
20,800
10,600
Circuitry factor (to plant)*
1.06
1.2
1.3
Utilization factor
0.50
0.36
0.22
Overflow factor
1.00
0.87
0.67
Av. travel speed in region (MPH)
25
15
10
Av. speed in region to plant
30
22
15
Loading rate (liter per hour)
31,800
27,250
22,500
Waiting time in region (hr.)
.08
.17
.25
Waiting time at plant (hr.)
.05
.10
.20
Dri vers per truck
1.0
1.0
1.25
Driver labor rate ($ per hour)
6.00
7.00
9.88
Support workers per truck
0
0
.25
Support worker labor rate ($)
"
"
5.81
Truck insurance ($)
1400
1440
1500
1 To account for trucks travelling over roads rather than in
a straight line.
ABOUT 35 MILES
Figure 5: Location of Significant Residue Amounts
Transport Modeling
In order to estimate the contribution of transportation costs
to overall treatment and disposal costs for a centralized man-
agement system a computer model, Pick-up to Plant (PUP), was
utilized to evaluate alternatives. The model simulates direct de-
livery of residues to the treatment site by vehicles servicing the
individual industries. The sensitivity of transportation costs to
treatment plant location, residue volumes and equipment and
labor costs was evaluated. A detailed description of the PUP
model is not presented in this paper.
Compilations of residues amounts broken down by the ten
collection districts in Allegheny County clearly shows major
concentrations in the heavy industrial districts, primarily the
Monongahela River Valley (Figure 5).
Existing and future landfill sites designated in a previously de-
veloped Allegheny County solid waste plan were used for plant
locations in the model. The sites would not necessarily be used
for a central disposal facility. Three sites near the Monongahela
industrial district, (South and South Central) in Forward and
South Park Townships and Monroeville Borough were evalu-
ated. In addition, two other sites in Kennedy and Findlay
Townships were chosen to test sensitivity of transport costs to
various plant locations. The Forward Township site was
modeled on a "good," "average," and "worst" case basis to
illustrate the range in transport costs which can be expected in
response to a number of variables listed in Table IV.
Results
A summarization of the number of trucks needed and total
costs by residue classification for each of six cases is presented in
Table V. The three cases for the Forward Township site indicate
that transport costs can vary from less than half to over five
times the average cost dependent upon truck size, labor rates,
utilization of equipment, and other factors.
-------
264 Allegheny County—I
Table V: Projected Transportation Costs
PLANT LOCATION:
Case:
FORWARD
Good
FORWARD
Average
forward
Worst
<; PARK
Average
KENNEDY
Average
FINDLAY
Average
MONROEVILLE
Average
Residue Class
T * Tc
T < \
T t TC
T I Tc
T 4 Tc
T * Tc
T * TC
Oil (A1-A7)
.7 .21 48
1.5 .46 103
7.5 2-8 617
1.5 .44 99
1.6 .48 107
2.0 .63 141
1.4 .43 96
Oil + Crankcase (A1-A8)
1.3 .23 87
2.9 .53 197
13.3 3.0 1100
2.8 .51 189
2.8 .51 188
3.5 .65 241
2.7 .50 185
Solvents (B1-B4)
.4 .66 27
.9 1.5 60
4.4 8.9 364
.8 1.4 57
• 7 1.1 45 "1
.9 1.5 62
.7 1.2 50
Pic. Liq. (03) +¦ Fe (0H)3 (Dl)
16.9 .22 1120
37.3 .49 2560
201 3.2 15300
34.2 .45 2330
40.2 .54 2790
48.1 .61 3150
40.4 .54 2790
Metal Finishing (D2)
1.2 .25 83
2.7 .57 189
14.7 3.7 1220
2.5 .52 172
2.5 .52 171 1
3.0 .62 206
2.8 .58 193
Hazardous Wastes (F1-F7)
1.6 .21 106
3.3 .44 228
16.9 2.7 1403
3.4 .45 232
3.3 .44 228
4.4 .60 309
3.2 .43 220
Foundry Sand + Met. (D8, El)
1.5 .24 108
3.2 .53 224
16.9 3.3 1406
3.1 .51 215
2.6 .41 174
3.4 .57 239
2.9 .48 202
Metallic Solids (D5-D7)
12.7 .22 842
26.6 .47 1830
142 3.0 11800
24.8 .44 1670
25,9 .46 1780
33.5 .60 2340
25.7 .45 1760
TOTALS
36.3 2421 78.4 5391 417. 7 34210 73. 1 ""M 79.1 5483 97.9 6688 79,8 5496
T - Number of Trucks
t - Cents per liter or kg
- Total Cost $ x 1000
Location of the treatment facility within the County appears
to be quite significant, since total yearly transportation cost to
the Findlay Township site is projected at approximately $2
million more than the most economic site in South Park
Township (6.7 to 4.7 million). Any savings in land acquisition
costs accrued by utilizing strip-mined areas in Findlay Town-
ship would, therefore, be quickly lost to higher transportation
costs.
In this example, the South Park Landfill site is best suited for
a treatment facility location, if enough land is available. On the
average, approximately $1 million would be saved in yearly
transport costs over the Forward and Kennedy Township sites.
Quantities used to develop the costs in Table 10 include metal-
containing solids. Excluding metallic solids, transport of
remaining residues to be handled would require a fleet of 49
trucks at an annual cost of approximately $3.3 million. The
additional collection of crankcase oil from approximately 600
gas stations did not significantly raise collection and transport
costs in the waste oil classification (from .42 to ,48c per liter);
therefore collection of waste oil from these additional sources
could provide savings through economy of scale for an oil
reclamation facility. The collection costs for spent solvents is
considerably higher than other residues (1.3c Titer) due to small
volumes; however, disposal costs for these types of residue are
currently very high, thus making transportation costs less of a
factor. Transport of spent solvents to the centralized facility for
processing does appear attractive.
The three possible plant locations near the Monongahela
Industrial district are comparable in transportation costs, dif-
fering by only approximately 8% from lowest (S. Park) to
highest (Forward). The Monroeville site is the least cost alter-
native from the point of view of transportation of all classes of
residue except pickle liquor and metallic solids. If pickle liquor
is to be treated at a separate site and metallic solids are not
handled, Monroeville thus becomes the most cost-effective site;
however, land costs are higher and must be considered in the
overall economics. If suitable land can be obtained at South
Park at comparable costs to Forward Township or Monroeville,
it would be the most desirable location for a treatment and
disposal facility to treat all classifications of residues.
-------
An Industrial Residue
Management System
for Allegheny County,
Pennsylvania—Part II Edward J. Martin
David L. Guthrie
Environmental Quality Systems, Inc.
Rockville, Maryland
Donald Berman
Department of Works,
Allegheny County, Pennsylvania
Treatment and Disposal Alternatives
Industrial and other operations in Allegheny County generate
toxic wastes, hazardous materials, and various other residues.
All sectors contribute to this waste generation, including indus-
try, agriculture, government, hospitals, and laboratories.
Existing residue handling, treatment and disposal technology
can be used to:1
1. Reduce the amount of hazardous wastes generated.
2. Concentrate waste streams at the source to reduce handling
and transportation problems.
3. Reuse wastes from one facility as raw materials of another.
4. Recapture and recycle metals, energy-containing wastes, and
other natural resources contained in toxic wastes and
residues.
5. Detoxify and neutralize wastes destined for land disposal,
thereby reducing the adverse environmental impact of this
option.
Because of the wide range of source types, all types of solid
and liquid residues are generated in Allegheny County. About
10% of the total residue generation in Allegheny County may be
considered hazardous as categorized in this paper.
As a first step in formulating the industrial residue process
system, each waste type was analyzed regarding current waste
disposal practices, other available options within the County for
waste disposal, the adequacy of those operations, and any plans
for expansion of existing facilities. These efforts are summa-
rized in Part I of this paper.
Secondly, existing residue disposal practices were analyzed in
the context of the three possible options for process selection as
a part of an area-wide industrial residue management system.
Those options are:
1. To leave the existing system as it is, implying that the existing
process or system is handling the waste in an efficient, cost-
effective, and environmentally-sound manner.
2. To modify an existing system, indicating that the existing
system may need to be structurally upgraded; non-structural
controls may be implemented; or that changes in the existing
system should be made to make the system more efficient,
cost-effective and environmentally-sound.
3. To develop or encourage a new management system, consid-
ering treatment and handling of the wastes, resource recov-
ery techniques, and new waste disposal options.
Using the criteria of protecting public health, minimizing
adverse environmental impact, and conserving natural resour-
ces, goals were established for an area-wide system. These
include:
1. Making reuse/ recycle—resource recovery a primary objec-
tive.
2. Emphasizing the "waste exchange" concept as an integral
part.
3. Collecting and treating all residues.
4. Minimizing incineration to alleviate air pollution episodes in
the County.
5. Minimizing the quantity of material to be transported to
increase cost-effectiveness.
6. Encouraging handling and treatment by the private sector.
Many alternatives were considered. Some of these processes
include electromagnetic metal recovery, chemical precipitation,
refrigeration and crystallization, brickmaking, resintering, dis-
tillation, and solvent extraction. Following is a description of
the process alternatives considered, inducting the equipment
required, personnel, operating and management needs, advan-
tages and disadvantages, and operation and maintenance, and
capital costs.
The current disposal practices for residues in Allegheny
County were examined and are presented in Part I. Twelve
residue types are currently being reclaimed by private enter-
prizes. Nine residue types are being lagooned, landfilled or
stockpiled on-site and on company-owned disposal areas.
Ongoing reclamation activities include iron slag (83% of the
total for metal value and road building purposes), steel slag
(10% of the total for road building) and foundry sand (20% of
the total). For those residues inadequately treated (See Table I)
treatment and/ or disposal schemes are proposed herein.
W ith the implementation of more advanced wastewater treat-
ment technologies, total residue quantities for all categories are
expected to increase. The maximum possible residue quantity is
produced with the implementation of zero discharge (of
pollutants) treatment technology, and after industrial expan-
sion.
As plant efficiencies for recycle/ reuse improve, however, the
quantity of residue is expected to decrease. Currently, blast fur-
nace dust, mill scale, coke breeze, sinter dust, kiln dust, and coal
fines have significantly high in-plant recycle—reclamation rates.
As another example, if an industry is told that the cost for waste
265
-------
266 Allegheny County—II
oil reclamation will be reasonably high, money will be saved if
less waste oil is produced.
Table I: Current County Residue Reclamation
Category Category Name
Wastes Adequately Treated
C3 Coal Fines
D5 Air Pollution Control Dusts
D6 Scrubber Sludges
D7 Scale
D8 Foundry Metallic Air Pollution Control Dusts
D9 Other
E2 Iron Slag
E3 Steel Slag
E4 FGD Sludge
E5 Cullet, Glass Manufacturing
E6 Cement Dust
E7 Water Treatment
E8 Fly Ash
Wastes Inadequately Treated
A1-A8 Oily Wastes
B1 Paint
B2 Resin Manufacturing
B3 Metal Cleaning
B4 Printing, Litho.
CI Food Processing
C4 Municipal Wastewater Sludge
C5 Cleaning Emulsions
D1 Iron Hydroxide Sludge
D2 Metal Finishing
D3 Spent H2SO4 Pickle Liquor
El Foundry Sand
F2 Caustics
F3 Organics
F4 Waste Paint, Dye
F5 Inorganics
F6 Coke Production
F7 Pitch Sand, Tar
Modular systems are designed and installed for recycle and
reclamation of residues, with a view to possible expansion as the
system is better understood with the passing of time. Relative
residue quantities for different waste treatment schemes are
shown in Figure 1. This relative diagram may change for a par-
ticular industrial sector because of different BPT and BAT
requirements. For example, in the electroplating industry, BAT
includes zero discharge of process water. Therefore, the relative
residue quantity expected would be more than for other indus-
tries.
The "module method" for waste and residue treatment has
five advantages. These are:
1. easy expansion of system capacity.
2. simplified cost determinations,
3. no "overdesigning,"
4. possible placement of several modules in different locations
thus guaranteeing flexibility, and
5. improved cost-effectiveness
The major disadvantage of modular systems is decreased
economy of scale.
For process design purposes, the maximum possible residue
quantity produced for each inadequately handled waste
category as given in Table I was calculated. These quantities
appear in Table II and reflect zero discharge requirements and
industrial expansion and/ or production increases. Residue
quantities are assumed to increase linearly until 198S based on
BPT residue amounts and BAT residue amounts reflecting
industrial growth. For metal finishing, organic, inorganic, and
coke production residues, the loadings resulting after BAT
treatment technology implementation were assumed to be
totally converted to residues by 1985 to account for residue pro-
duction by zero discharge treatment schemes. These residues are
included in the 1985 data on Table U and were used as the
maximum process design values for the industrial residue man-
agement plan.
RESIDUE QUANTITY
Current Load
(Individual sources)
Extrapolation to
whole SIC
BPT Projection
BAT Projection
BAT Projection +
Indust. Expan. Proj.
Zero Discharge +
Industrial Expansion
Projection
Zero Discharge *
Industrial Expansion
Improved Plant
Efficiency
Zero Discharge +
Industrial Expansion
Process Change +
Changes from Area-
wide System Costs
Modular Design
Capaci ty
Figure 1: Relative Expected Residue Quantities For Different
Waste Treatment Schemes
Process systems designed for residue recycling/ reclamation
are based on Table II data for the maximum residue quantity. If
possible, unit process modules are recommended for residue
treatment, based on some fraction of 1985 residue quantities.
The " Waste Exchange"
During the past four years, waste exchanges have been estab-
lished in over ten European countries.2 The U nited States fol-
lowed suit, and waste exchange clearinghouses have recently
been established. Both clearinghouse operations are similar to
those in Europe. The clearinghouses are listed in Table III.
The first United States clearinghouse was established in St.
Louis on October 30, 1975.3 Through the clearinghouse, waste
producers and waste users maintain a lively correspondence.
Approximately 50% of the material offered for exchange had a
market.4 Although approximately 89% of the materials listed as
available, or three million metric tons by weight, was diluted sul-
furic acid (January, 1976 listing), other materials traded in the
exchange are inorganic chemicals, solvents, copper, coal tar,
baghouse dust, waste oil, lime slurry, and 25% nitrogen. Other
materials are very difficult to dispose of by the waste exchange
method, including wastewater sludge, filter cakes and fly ash.
In Iowa, the Industrial Waste Information Exchange was
founded in April, 1976, and is conducted by the Center for
Industrial Research and Service (CIRAS) at Iowa State Univer-
-------
Allegheny County—II 267
Table II: Design Residue Quantities
Industrial
1985'
Used BAT
Growth
Residues
(kkg/day)
Maximum
Guidelines For Factor
(kkg/day)
Wastes
Inadequately Treated
Calculation
(K)
1977
1983
(1983)'
Values
A1
WWT Sludqe
X
1.8
2.3
2.3
3.15
5.151
A2
Machinery Lubricants
1.0
0.2
0.2
0.2
0.2
A3
Hydrauli c Oi1
1.0
0
0
0
0
A4
Emulsions
1.0
4.0
4.0
4.0
4.0
A5
Animal Oils & Fats
X
1.0
1.5
1.5
1.5
2.251
A6
Cutting Oil
1.5
45
51
62.8
68.7
A7
Tank Bottoms
1.3
2.4
3.5
4.0
4.53
A8
Crankcase Oil
1.0
43
43
43
43
Total
Oily Wastes
128
B1
Paint Manufacturing
1.2
8.9
8.9
9.72
10.0
32
Resin Manufacturing
1.7
0.69
0.69
0.91
0.98
B3
Metal Cleaning
1.0
0.90
0.90
0.90
0.90
B4
Printing, Lithographing
1.0
0.17
0.17
0.17
0.17
Total
Waste Solvents
12.1
CI
Food Processing
1.0
16
16
16
16 ,
C4
Municipal Wastewater Treatment
X
1.0
640
670
670
1120 L
C5
Cleaning Emulsions
1.3
3.8
6.5
7.4
8.6
Total
Organics
1145
D1
Iron Hydroxide
1.3
1100
2140
2436
2880
D2
Metal Finishing
X
1.5
91
92
113
120
D3
HjSO, Pickle Liquor
1.5
420
420
517
549
Total
Heavy Metal-Containing Wastes
3550
El
Foundry Sand
3.0
96
96
185
215
Total
Inorgani cs
215
1 Assume increase by 50% due to zero discharge considering the quantity represents a small percentage
of the total.
Table II (cont.)
Industrial 1985'
Used BAT Growth Residues (kkg/day) Maximum
Guidelines For Factor (kkg/day)
Wastes Inadequately Treated Calculation (K) 1977 1983 (1983)' Values
F2
Caustics
1.2
9.3
9.3
10.2
10.4
F3
Organics X
4.0
22
22
52.5
62.7
F4
Waste Paint
1.2
5.6
5.6
5.12
6.3
F5
Inorganics X
1.7
4.0
4.0
5.3
5.75
F6
Coke Production X
1.3
38
85
96.8
117.4
F7
Pitch Sand, Tar
1.3
20
20
22.8
23.7
Total
Other Hazardous Wastes
226
D7
Scale
1.4
9.7
279
330
437
D9
Other Heavy Metal-Containing Wastes
1.0
1.5
1.5
1.5
1.5
E3
Steel Slag
1.3
3200
2200
2500
2270
E5
Cullet, Glass Manufacturing
1.2
4.2
5.6
6.1
6.7
Total
Selected Heavy Metal-Containing and
Inorganic Residues
2715
Total
All Categories Wastes Inadequately Treated
2575
3703
5276
2 Use average 1975 annual ALCOSAN flow = 180 MGD
Municipal sludge assumes the following train:
Process
lb. dry solids/MG
Primary
1000 7
Organic
Secondary Act. Sludge
700 J
Bio-residue = 1700 x
180 = 139 kkg/day x 5 (20% solids) = 695
Alum addition to secondary
450"}
Nitrification
01
"Chemical"
Filtration
125 \
Sludge = 610 x 180 =
49.8 kkg/day x 5 (20% solids) = 250
Carbon Adsorption
35V
RO
2085**
Residue = 2085 x 180 = 170 kkg/day 170
In Brine Total TR5
* 500 lb. carbon spent/MG x 7% loss = 35 lb./MG
** Assumes: pretreatment is sufficient; 90% product recovery; and 250 mg/1 inorganic solids removed from sewage.
Therefore, per 10b lb. water treated, 100,000 lbs. is rejected waste containing 250 lbs. solid residue. This
is equivalent to 2085 lbs/MG treated. (Fair, G.M., and Geyer, J.C. Water Supply and Wastewater Disposal. John
Wiley & Sons: New York. 1956; and Metcalf & Eddy Engineers Report to National Commission on Water QuaTity on
Assessment of Technologies and Costs for Publicly-Owned Treatment Works. Vols. 1-3. Boston, Mass. Sept., 1975).
-------
268 Allegheny County—II
siiy (Ames, Iowa). In their first listing,2 available materials
included waste oils, wood products, and paper products.
Two cities have recently begun waste exchange operations.
Organizations exist in Atlanta and Houston.5 At the time of this
paper, complete information about these exchanges was
unavailable.
I ABLE III: Waste Exchange Clearinghouses in the U.S. and
Europe*
Netherlands
Belgium
West Germany
Austria
Swi tzerland
Denmark
Norvay
Sweden
Finland
United Kingdom
U.S./Missouri
U.S./Iowa
Name of Clearinghouse
Association of Dutch Chemical
Industries
Belgium Chemical Industry
Association
Chemical Industry Association
(Joined West Germany's
Association)
Swiss Society for the Chemical
Industry; Association of
Swiss Paint and Varnish
Manufacturers; Union of
Soap and Detergent Manu-
facturers
Nordic Waste Exchange (Nordic
Intergovernmental Foundati on)
Department of the Environment
Waste Exchange Clearinghouse
St. Louis Waste Exchange
Iowa Industrial Waste Information
Exchange
natn Established!
1972
1972
1972
1972
1973
1974
1976
1976
L* Other operations than those listed here are probably in operation
within the recent past. _
Centralized Facilities
Clearinghouses in Europe divert residue materials to central-
ized facilities. In Denmark, the Nordic Waste Exchange facility
handles waste oils, solvents, organic chemical wastes, halogen-
containing debris, inorganic chemical wastes, and soil, sand,
and old packing, created because of operational breakdowns.6
The system uses approximately 25 large collection points includ-
ing rail transportation for receiving hazardous liquids in tanks
or sealed in drums. These central points are no more than 30
miles apart. At least one pickup station is established within
each municipality.
Processes at the plant included specialized waste incineration,
distillation of solvents, and hydrochloric acid regeneration,
which would produce ferric oxide in granular form. The plant is
currently having economic problems because charges made
appear to be insufficient to cover the actual operation costs of
the facility.6
Another facility combines industrial waste with municipal
waste for treatment in Germany.7 Industries in the locale may
transport the residual materials to the facility, which receives
any and all materials including toxic materials such as arsenic,
cyanide, and a few chlorinated hydrocarbons (pesticides are
stored for future disposal). The plant is essentially a detoxifica-
tion plant. A fee is collected depending upon the amount of
treatment needed and the quantity of the waste.
A third facility is planned in Ventura County, California, to
be operated by the Ventura Regional County Sanitation Dis-
trict.8 The residual waste treatment facility will receive metal,
brine, non-metallic toxic, oily and organic wastes. Metal wastes
will be treated by carbon adsorption, ion exchange, and regener-
ation with sulfuric acid. Brine wastes will be treated by API sep-
aration, flotation-sedimentation, and polymer addition. Non-
metallic toxic wastes will be treated by flotation-sedimentation,
carbon adsorption and reverse osmosis. Oily wastes will be
mixed with non-metallic toxic wastes after API separation and
polymer addition. Organic wastes will be treated separately by
pyrolysis and incineration. It is estimated that the project will
require three years to complete, including one year of facility test
operations to capture wastes produced on a cyclical basis.
A recent study about waste exchange concepts indicated that
a hierarchy of industries is involved.9 Industries requiring high
raw material purity tend to sell their wastes to industries requir-
ing lower raw material purity. Therefore, if a diversity of indus-
tries are involved in buying and selling wastes, the exchange may
work.
The study1* recommended that governmental agencies should
not run waste exchanges because of their ability to regulate and
problems associated with the confidentiality of waste stream
constituents. Another institution such as a Chamber of Com-
merce should manage the waste exchange. Currently-existing
U.S. waste exchanges are not government operated. The waste
exchange may be started as a first step while final planning of an
area-wide program is underway. The feasibility of the exchange
will develop if the sources and buyers exist.
The Area- Wide System
The industrial residue management system is a summation of
all treatment and disposal processes, including landfill, trans-
portation (haul), and incineration requirements. The system is
illustrated in Figure 2.
System processes are summarized in Figure 2. Final manage-
ment alternatives and selected process costs are given in Table
IV. The preliminary total annual cost and load summary is pres-
ented in Table V.
Table V: Preliminary Total Annual Cost and Load Summary
CAPITAL COST 1
TOTAL ANNUAL COST1
ADMINISTRATION
0.34
TRANSPORTATION
TREATMENT AND DISPOSAL 30.4
16.43
TOTAL QUANTITY (1983 value)
15,840 kkg/day
TOTAL QUANTITY BEING PROCESSED
8,020 kkg/day
1 1976 dollars * 106
2 The South Park Landfill and processing site cost estimates were
chosen.
3 Net annual cost 1s $9.80 million. Some modular costs are Included.
Table V is a compilation of several items: administration,
transportation, and treatment and disposal costs. These repre-
sent the total industrial residue management system costs.
Administration and non-administrative costs for main office
and support personnel are given in Table VI. Table VII presents
preliminary treatment and disposal costs by unit process. Net
unit costs are estimated in Table VIII.
Landfills
In the industrial residue management system, there are two
different landfill types: a scientific landfill and a landfill
resembling a sanitary landfill operation. The quantities of
residues sent to each and their respective unit costs are summa-
rized in Table IX.
-------
Allegheny County—II 269
Table IV: The Industrial Residue Management System
ITEM
NAME
DISPOSITION
BY
WHOM
NET TOTAL
ANNUAL CAPITAL
COST** COST**
COMMENT
1. A1
WWT Sludge
Landfil1
County
--
Sanitary Landfil 1
(See Table 9)
2. A2 thru
A6, A8
Waste Oil
Reclaim
County
7.02
Almost break even with
current higher sale prices.
3. A7
Tank bottoms
Incinerate
County
--
See Table 10
4. B1 thru
B4
Solvent***
Reclaim
PPG/
County
0.24* 0.04*
Ask PPG to take remainder.
4a. CI
Ind. Organic
Sludges
To ALCOSAN
County
0.039
Haul 16 kkg/day (1985)
4b. C5
Cleaning
Emulsions
To ALCOSAN
County
(See 4a)
Haul 8.6 kkg/day (1985)
5. Part of
C4
Lime Sludges
PO4 treat.
Landfi11
County
(disposal
only)
--
Municipal plants
(See Table 9)
5. Part of
C4
Organic Sludges
Muni cipal
To ALCOSAN
County
1.07
Haul 695 kkg/day (1985)
5a. C3
Coal Fines
Lagoon
on-si te
Coal
companies
No cost to County.
6. D1
Hydroxide
Sludges from
Pickle liquor
Landfill as
interim
alternati ve
Steel
Companies
County
Landfill as Interim
alternative (See
Table 9)
1985 cost not assignable
here since net benefit to
steel industry.
Current costs landfill
Don't produce spent liquor;
reclaim as pickling acid.
7. D2
Metal Finish.
Sludges***
Reclaim
Metals
County
0.63 8.66
Landfill remains.
Net $ after metals value.
8. D3
HoSO. Pickle
Liquor***
Reclaim
County
0.47 0.55
9. D5
APC Dusts
Landfil1/
Recycle
Steel
Companies
No costs to County.
(See Table 11).
10. D6
Blast Furnace
Scrubber
Sludges
Landfill/
Treatment
Steel
Companies
(See Table 11)..
11. D7
Scale
Landfill
County
(See Table 9)
haul 9 437 kkg/day (1985).
TTso" see Table 11).
12. D8
APC Foundry
Haul only
Companies
-
(See Table 11).
13. D9
Other HM
Wastes
Scientific
Landfill
County
(See Table 9)
haul » l.b kkg/day (1985)
14. El
Waste
Foundry
Sand***
Reclaim
County
-0.55 0.17
As a service with beach
cleaner.
No haul c.ost.
15. E2
Iron Slag
Reclaim
Fe & Granulated
Slag
Ouquesne
Slag
Profit for Private
Sector
Duquesne Slag handles now
plus some small stockpiled
quantities. No haul cost.
16. E3
Steel Slag
Demetallize
(optional)
Landfill
County
(See Table 11)
(See Table 9)
haul 9 2270 kkg/day (1985).
•Costs included as a contingency. ***Modular costs are given as follows:
** 1976 dollars * 106 Item Module Size
4. Solvent 1000 gal/day
7. Metal finishing sludges 91kkg/day
8. H2S04 pickle liquor 208kkg/day
14. Waste foundry sand 27kkg/hour
-------
270 Allegheny County—II
Table IV (cont.)
ITEM
17. E4
18. E5
19. E6
20. E7
21. E8
22. F2
23. F3
24. F4
25. F5
26. F6 and Plant
Residues
27. F7
NAME
FGD Sludge
Cullet & Glass
Manufacturing
Cement Dust
Water Trt.
Sludges
Fly Ash
Dust
Causti cs
Organics
Waste Paint
Hazardous
Inorganics
Coke Production
Pitch Sand,
Tar
DISPOSITION
Chemi cal
Fixing
Landfi11
Landfi11
on-site
Landfi11
Landfill on-
site (Reclaim
as bricks:
optional)
Neutralize
Landfi11
Incineration
Incineration
Encapsulate
Landfi11
Incineration
BY
WHOM
Power
Companies
County
Borough
Power
Companies
NET
ANNUAL
COST**
TOTAL
CAPITAL
COST**
(See Table 11)
COMMENT
Cost not assignable. Let
power companies handle
by fixing; no haul cost.
See Table 11 also.
(See Table 9)
(See Table 9 and 11) [to cost to County.
No cost to County.
County 0.004 0.02
(See Table 9)
County (See Table 10)
County (See Table 10)
County 0.037 0.02
(See Table 7)
County (See Table 9)
County (See Table 10)
County encourages a
business venture. (See Table 11)
No costs assignable.
Include haul costs 3 21 kkg/day
(1985): (See Table 9).
Hau_L(3 5,75 kkg/day (1985):
(See Table 9).
i tpd l TPD
ABSORBENT LIGHT ENDS
2.4 TPD
ADDITIVES
100 TPD
WASTE
OIL -H
REACTOR/
SETTLER
STRIPPING
10 TPD BS 1 W
4 TPD NAPTHA I
LIGHT ENDS
50 TPD
ABSORPTION
—~PRODUCT
OIL
0.3 TPD
ABSORBENT/OIL MI*
44 TPD SOLVENT
i
incinerator!
SOLVENT
EXTRACTION
-~r~
3.5 TPO
BOTTOM^"
43 TPO
OVERHEADS
36 TPD
.PRODUCT OIL
766 TPD MET
ORGANIC _
SLUDGE
27 TPD UET
FOCD PROCESSING
SLUDGE AND
CLEANING EMULSIONS
5700 TPD OF
10 RESIDUE
CATEGORIES
7b0 pSAr!«
CONDENSER
1.04 WET TPD SLUDGE
EVAPORATOR
I
1000 gal/day
WASTE
SOLVENT
(MODULE)
OIL
SEPARATION
FOUNDRY
SAND
AIR
FROTH
FLOTATION
VIBRATING
SCREEN
30 Ton/Hr
— WASTE
FOUNDRY
SANO
(>*0Din.E)
U TPD H?S0.
PICKLE LIQUOR
229 TPD
[SPENT
SULFURIC
ACID Hf
PICKLE
LIQUOR
(MODULE)
TREATING
AND
REFRIGERATION
CRYSTALLIZATION
AND
STORAGE
132 TPD
~SULFURIC
ACID
97 TPD
FERROUS SULFATE
HEPTAHYDRATE
673 lb/DAY MAX OIL IN
WASTE WATER
NICKEL
1
NICKEL
RECOVERY
AMMONIA
CALCIUM 1.0X1 SODIUH CARBONATE
COPPER
4
COPPER
RECOVERY
132 TPD
-METAL-FINISHIngI
HYDROXIDE 1
SLUOGE
CARBONATE
ROASTING
SANITARY AND
SCIENTIFIC
LANDFILL
SLUDGE
SULFURIC ACin
CHROMATE
CHROMATE
RECOVERY
LEACHING
&
SOLIDS REMOVAL
SODIUM
*BI SULFATE
wirER-
~r~
chromium
SODIuh
SULFATE
Figure 2: Industrial Residue Management System
i rnw • 1 SHORT Ton ¦ Z000 POUNDS
-------
Allegheny County—II 271
Table VI: Allegheny County Industrial Residue Management
Facility
Table VIII: Preliminary (Net Unit Costs)
ADMINISTRATION COSTS
1 Plant Engineer
2 Assistant Engineers
3 Shift Supervisors
3 Clerks
2 Secretaries/Receptionists
1 "Broker"
1 Dispatcher (optional)
$235,500
PLANT OPERATING COSTS
2 Engineers
36 Operators
Included in
Costs
LANDFILL COSTS
2 Supervisor/Operators
2 Buildozer Operators
58,500
45,000
INCINERATOR
1 Operator
Included in
Costs
TOTAL
$339,000
Table VII: Preliminary Treatment and Disposal Cost Sum-
mary1
SYSTEM ELEMENT
CAPITAL
TOTAL
ANNUAL COST
NET
ANNUAL
Oil Reclamation (A2-A6, A8)
7.02
2.32
--
Solvent Recovery (B1-B4)3
0.04
0.03
- 0.24
Industrial Organic Sludge^ (C1+C5)
--
0.038
0.038
Municipal Organic Sludge^ (C4)
--
1.07
1.07
Municipal Inorganic Sludge^ (C4)
--
0.68
0.68
Iron Hydroxide Sljdge (Dl)
(Included
in Landfill Costs)
Metal Finishing (D2)^
8.66
3.37
0.63
H2S04 Pickle Liquor (D3)3
0.55
0.18
-0.47
Foundry Sand (El)
0.17
0.095
-0.55
Caustics (F2)
0.02
0.004
0.004
Organlcs, Waste Paint
Pitch, Sand, Tar (F3, F4, F7)
(Included in Incinerator Costs)
Inorganics (F5)
0.02
0.037
0.037
Coke Production Wastes (F6)
(Included in Scientific Landfill
Costs)
Scientific Landfill (See Table 9)
7.27
2.99
2.99
Landfill (See Table 9)
6.33
5.53
5.53
Incinerator (See Table 10)
0.32
0.076
0.076
Totals
30.4
16.4
9.80
1 1976 dollars x 106
2 Sludge disposal to existing ALCOSAN plant (ref. 26)
3
Modular costs are given as follows:
Solvent
Metal finishing sludges
H0SO4 pickle liquor
Waste foundry sand
1000 gal/day
91 kkg/day
20B kkg/day
27 kkg/hour
Hazardous Wastes Incineration
Table X presents the wastes to be incinerated in Allggheny
County with their associated costs. Approximately 85% of the
total residues to be incinerated in Allegheny County are the bio-
sludges which are recommended to be incinerated by ALCO-
SAN. The incineration costs presented are for a hazardous
wastes incinerator.25
Description and Discussion of Alternatives
For the categories listed in Table IX, alternatives were con-
sidered to formulate an area-wide residue disposal system.
Following is a description of the process alternatives consid-
ered, including the equipment required, personnel, operating
and management needs, advantages and disadvantages, econo-
mies of scale, operation and maintenance, and capital costs.
SYSTEM ELEMENT
COST1
Oil Reclamation
$60/kkg
Solvent Recovery
$ ,67/gal
2
Industrial Organic Sludge
$4,21/kkg
2
Municipal Organic Sludge
$4.20/kkg
Municipal Inorganic Sludge
$5.51/kkg
Metal Finishing Hydroxide Sludge
$19/kkg
Pickle Liquor (Sulfate)
$6.23/kkg
Waste Foundry Sand
$9.29/k kg
Caustic (excludes landfill cost)
$1.16/kkg
Scientific Landfill
$5 7/kkg
Sanitary Landfill
$3.50/kkg
Incinerator
$1.75/kkg
1976 dollars.
Sludge disposal to existing ALCOSAN plant.
Heavy Metal-Containing Wastes (D1-D3)
Approximately 2880 kkg/ day of iron hydroxide sludges (D1),
resulting from the neutralization of pickle liquor and treatment
of acid rinse waters, will be produced in Allegheny County by
1985. The current method of disposal is by landfill in Allegheny,
and surrounding Beaver, Washington, and Westmoreland
Counties.
The treatment alternatives are: (1) utilize the present landfill
system; (2) discontinue production of iron hydroxide sludges
and reclaim as pickle liquor; or (3) discontinue production of
iron hydroxide sludges and reclaim partly as pickle liquor and
partly as heavy metal-containing wastes. The alternative chosen
was to discourage the production of hydroxide sludges by
discontinuing neutralization processes. Instead, the pickle
liquor is recommended to be reclaimed. The proposed amount
of iron hydroxide sludge in 1985 will be zero. Until then, sludge
will be landfilled.
Metal finishing and wire production account for the majority
of metalfinishing residues (D2) generated in Allegheny County.
From Table IX, approximately 120 kkg/day of these residues
will be produced by 1985.
There are three alternatives for reclaiming metal finishing
residues: (1) use current disposal methods; (2) transport to a rec-
lamation facility under development by Internatial Nickel in
Beaver County and scheduled forcompletion in mid-1978; or (3)
install a centrally-operated resource recovery operation. Of
these alternatives, reclamation by the Beaver County facility is
probably the best choice.
Three processes were investigated to treat metal-finishing
sludges generated by Allegheny County industries: (1) chemical
precipitation processes, (2) reverse osmosis10, and (3) carbonate
process."
Of these, the recently-developed carbonate process appears to
be the most feasible but is still in the development stage.
The process steps: leaching with ammonia (NH 3), pressure fil-
tration, and electrolysis for copper and nickel, respectively, pro-
duce a filter cake and marketable copper and nickel. The filter
cake is combined with quicklime (CaO) and sodium carbonate
and roasted, leached with water and pressure filtered, producing
a chromate liquor and a residual sludge. A series of gvaporators,
reactors (with sulfuric acid, followed by thickening and drying),
result in marketable sodium sulfate (Na2S04) and chromium
oxide (Cr03).
-------
272
Allegheny County—II
Table IX: Landfill Summary
sanitam landfill.-1
1965 Quantities
(KKG/dav) (Tons/day)
Tyje
Resi due
A1
Wastewater Treatment oily Sludge
5.2
5.7
C4
Lime-PO^ Sludge (Municipal)
420
460
D1
Iron Hydroxide
2880
3180
D7
Scale^
437
482
E3
Steel Slag
2270
2500
E5
Cullet, Glass Manufacturing
6.7
7.4
TOTALS
6020
6640
CAPITAL COST
TOTAL ANNUAL COST (@ $3.20/ton)
% 6,400.000
$ 7.760,000
SCIENTIFIC LANDFILL:3
Type
Residue
1985 Quantities
(KKG/day) JTons/dayj
D9
Other Heavy-Metal Containing Wastes
1.5
1.65
F2
4
Caustics
21*
23*
F5
5
Inorganics
5.75
6.34
F6
Coke Production
117
129
TOTALS
145
160
CAPITAL COST
TOTAL ANNUAL COST (0 $52/ton)
$ 7,270.000
$ 2,990,000
1. Uses 1976 dollars; life of landfill is 20 years; assumes work week is 6
weeks; (reference 27).
2. Does not include scale pit effluent treatment required by BATEA
"(1983).
3. Notes include:
(a) Total capital costs include study and design costs ($ 110,000),
land costs ($2.0 million), and other capital (equipment, build-
ings, etc.) costs ($5.16 million).
(b) Encapsulation of inorganics cost of $23,700 capital cost and
$36,500 operating cost not included in cost estimates.
(c) Life of landfill is 20 years.
(d) Assumes work week is 7 days.
(e) Includes waste segregation, deactivation, waste/ soil blending,
daily earth cover, leachate collection and treatment, a two foot
thick rolled-clay landfill liner, and encapsulation of inorganics
(F5).
(f) See reference 28.
4. Includes an equal quantity of spent sulfuric acid from pickling
(D3), which is added for neutralization. Costs for this process not
included.
5. These residues are encapsulated.
Sodium bisulfite and residual carbonate sludge are waste
products of the system. A wastewater is also generated.
In 1976 dollars, the total initial installed cost is approximately
$8.7 million. Costs for the system are given in Table IV.
No hydrochloric acid pickling processes are used in Allegheny
County. Sulfuric acid (H2S04) pickling processes are used
instead, and waste sulfuric acid pickle liquor (D3) from these
processes will be produced on the order of 550 kkg/ day by 1985.
This amount does not include the additional pickle liquor which
would be generated by discontinuing lime neutralization waste
treatment processes.
Four treatment alternatives exist: (1) Allegheny County could
reclaim the pickle liquor; (2) the pickle liquor could be trans-
ported to a private industry (even out-of-state) for reclamation;
(3) a portion of the pickle liquor could be used to neutralize the
hazardous caustic wastes (F2) generated within the County, and
the rest would be reclaimed; (4) the current waste treatment
practice of neutralisation would be continued. Of these alterna-
tives, combining a portion of the H2S04 pickle liquor with the
F2 wastes and reclaiming the remainder seems to be the most
feasible.
Table X: Residues To Be Incinerated
I*E£
Tank Bottoms
Adsorbant/0i 1 Mix
Bottoms
Light Ends, BS&W
Solvent Residuals
A7
A
A
A
B
C1.C5 Industrial Organic Sludges, Cleaning
Emulsions to ALC0SAN
C4 Municipal Wastewater Sludges
{organic residuals only to ALC0SAN)
F3 Organics
F4 Waste Paint
F7 Pitch Sand, Tar
TOTAL
total WITHOUT ALC0SAN SLUDGES
COSTS*
Total Capital Costs (includes Transportation)
Total Annual Costs
Net Operational Costs
6
* 1976 dollars x 10 . May be conservative.
1985 Quantity
(kkg/day)
4.53
0.35
4.14
17.7
3.01
24.6
695
62.7
6.3
23.7
842
147
$319,000
$ 75,800
$ 75,800
Table XI; Costs for Possible Alternatives
SUBCATEGORY
Scrubber Sludges (D6)
FGD Sludges (E4)
A1r Pollution Dust (D5)
Steel Slag (£3)
Foundry Sand & Metallic (D8)
Mill Scale (07)
Cement Dust (E6)
Cullet-Glass Prod. (E5)
Fly Ash (E8)
CAPITAL
0.61
8.46
COSTS 1 FOR 1983 QUANTITIES
TOTAL ANNUAL NET ANMIItl I
0.02
0.15
-9.12*
Costs in 1976 dollars * 10b
Landfill costs not Included
Using 501 of the County production and 3.5 1b/br1ck
9 $78/1000 bricks
-------
Allegheny County—II 273
Assuming a one-to-one capacity for neutralization, 10
kkg/day of H2S04 pickle liquor will be used, leaving approxi-
mately 540 kkg/day ofH SO pickle liqjior Jo be reclaimed. On
process suitable for spent H2S04reclamation was found.12
The process consists of the following 6 steps:
1. Cooling the acid and crystalizing ferrous sulfate heptahy-
drate (FeSo4 7H20) by refrigeration.
2. Partial separation of crystals in a settling tank.
3. Final filtration in an automatic self-cleaning filter.
4. Recovery of acid.
5. Reduction of iron from 12% to 2% (at 20% by weight acid
charge to the unit).
6. Removal and recovery of ferrous sulfate crystals from a
settling tank by pump to a storage tank.
The recovery of iron sulfate heptahydrate as a salable byprod-
uct is enhanced at higher concentrations of sulfuric acid. Typical
multi-stage pickling operations exhaust sulfuric acid down to
the 6-8% by-weight level and iron recovery potential would be
significantly reduced. Additionally, recirculation of the reco-
vered acid stream (at the range of 10% by-weight sulfuric acid) to
the first stage pickling would probably not be feasible because of
additional dilution in the live steam process. Dilution difficulties
in the first stage pickling could probably be circumvented by
installing a dry heating system for the pickling tanks using coils
heated by steam. Steam utilization would probably be reduced
over current live steam heating requirements. It is likely that the
volume of waste pickle liquor could be reduced since water
rather than live steam could be used to dilute the concentrated
sulfuric acid going to the head end of the pickling operation.
Sulfuric acid could be recovered at the 20%, 15%, or 8% by
weight level depending on the desired recovery of iron heptahy-
drate. Reclaimed acid could be recirculated, and equilibrium
iron levels would be reached in the pickling system, in balance
with that being removed through the recovery process. A spe-
cific detailed analysis would have to be made for each plant util-
izing the system.
In order to gain an insight into what reclamation could mean
from the point of view of this analysis, a series of assumptions
were made in order to derive the costs for the process application
which appears in Table VII. Each of two modules treating
30,000 gallons (208 metric tons per day) over a 24 hour cycle
would be needed to reclaim the sulfuric acid for pickle liquor
production levels in Allegheny County. Credits from the system
are gained by the sale of iron sulfate heptahydrate at about $15
per short ton and sulfuric acid at $50 per short ton. These credits
amount to about $650,000 per unit over a year's operation.
There is a potential additional cost saving of about 40% for addi-
tives which are recycled rather than lost (calculated at about
$85,000 per year for this example). Therefore, the net
operational cost of this system would show a profit of about
$470,000 per module. This is to be compared with costs (at about
5c per gallon) of approximately $550,000 per year.
Organics (CI, C4, C5)
As shown in Table IV, three types of municipal wastewater
treatment residues (C4) will be produced in Allegheny County
with the implementation of zero discharge treatment technology
in 1985. These are organic bio-residues, "chemical" sludges
resulting from chemical addition, and brine residues from
advanced waste treatment (AWT) with reverse osmosis.
Three treatment alternatives exist: (1) transport allC4 sludges
to the Allegheny County Sanitary Authority (ALCOSAN)
treatment facility, (2) transport bio-sludges to ALCOSAN and
landfill the hydroxide sludges, or (3) landfill on-site. Of these,
the second alternative is preferable, as the only additional costs
incurred by this unit process are incineration and landfill costs.
Landfill costs are accumulated and presented in Table IX.
Approximately 25 kkg/day of food processing (CI) and
organic cleaning emulsions (C5) residues will be produced in
Allegheny County by 1985. ALCOSAN currently disposes of
110 TPD of dry sludge (100 kkg/day). Food processing sludge
(16 kkg/day at 5% solids) amounts to0.8 dry kkg/day, or 0.7%
of the sludge currently disposed of by ALCOSAN. Cleaning
emulsions (at 5% solids) represent approximately 0.41% of the
sludge currently disposed of by ALCOSAN. Combined, CI and
C5 sludges represent less than 2% of the sludge volume currently
incinerated by ALCOSAN.
Other Hazardous Wastes (F2-F7)
Coke production residues (F6) comprise over 50% of the total
"other" hazardous wastes categories. These residues will
increase by over 200% within the next eight years due to the
start-up of new coke production works. At this time, there is no
technology to recycle these wastes, so the alternative presented is
landfilling.
Hazardous inorganics (F5) make up a small portion of the
total hazardous wastes category. Three alternatives exist for
treatment: (1) incinerate in a hazardous wastes incinerator, (2)
encapsulate in a hazardous materials landfill, or (3) landfill via a
commercial chemical fixation or stabilization method. Of these,
encapsulation was selected for minimum adverse environ-
mental impact.
Assuming a density equivalent to garbage13, 130 cubic feet-
/ day of hazardous inorganics are produced in Allegheny
County. The costs for encapsulation are given in Table IV. They
are derived from costs for other scrap encapsulation14. Other
techniques using polyurethane foam coatings have been devel-
oped in Germany.14
Hazardous organics (F3), paints and dyes (F4), and pitch
sand and tar (F7) will be produced at a rate of 93 kkg/day by
1985 in Allegheny County. These wastes constitute a problem
because of their nature, even though they represent less than 2%
of the total residues generated in Allegheny County.
Incineration or encapsulation management alternatives may
be used for F3, F4 and F7 residues. Costs are presented for the
incineration alternative in Table VII.
Hazardous caustics (F2) residue production in Allegheny
County will represent only 5% of the total "other hazardous"
residues by 1985. Four alternatives exist for treatment: (1) mix
with sulfuric acid pickle liquor (D3) and landfill the resulting
sludge in the hazardous wastes landfill; (2) store the caustics
directly in the hazardous wastes landfill; (3) sell via the "waste
exchange," or (4) incinerate in the hazardous wastes incinerator.
Of these four alternatives, mixing the hazardous caustics (F2)
wastes with spent sulfuric acid pickle liquor (D3) and landfilling
in the hazardous materials landfill was chosen. Any precipitate
formed would be landfilled also. Costs are presented in Table
VII.
Foundry Sand (El)
The number of foundries are expected to triple within the next
eight years in Allegheny County. This will result in an increase in
foundry sand (El) residues from almost 100 kkg/ day in 1977 to
over 200 kkg/day by 1985.
Two alternatives are available: (1) reclaim the spent foundry
sand, or (2) landfill with associated hauling costs. Reclamation
was chosen because of the potential value of the reclaimed sand.
In 1972, EPA devised a process to restore thequality of beach
sands contaminated from oil spills15. This system, consisting of a
portable unit mounted on a flatbed semitrailer, could be trans-
ported to each foundry, where reclamation would proceed on-
site. Demonstration data indicates a 94-98% oil recovery. The
oily wastes could go to the waste oil recovery process to be dis-
cussed later.
Costs for the unit appear in Table IV. By re-selling the
-------
274 Allegheny County—II
reclaimed sand or selling the reclamation service, a profit is
realized. The unit could be paid for within a short period.
Oily Wastes (A1-A8)
In view of the mounting energy shortage, oil recovery reuse
becomes more important. Six factors were taken into account as
the basis for proposing a waste oil reclamation facility. They
are:1*
1. Waste oils can be re-refined into quality products.
2. Waste oils represent a valuable resource which can be util-
ized to reduce energy and oil shortages.
3. Waste oils are being disposed of in ways which cause envi-
ronmental degradation.
4. Certain practices related to waste oil disposal such as
uncontrolled use as a fuel should be prohibited.
5. Both the Federal Water (PL 92-500) and Air Quality Acts
(PI 91-604) put tighter controls on disposing of waste oils.
6. Although waste oil generation rates represent a small per-
centage of the total oil used in the United States, they rep-
resent a significant percentage of oil shortages.
In Allegheny County, about 130 metric tons of seven waste oil
types (A 1, A2 A4-A-8) will be generated daily by 1985. Fifty-
four percent are cutting oils; 34% are crankcase and lubricating
oils; the remaining 12% are animal oils and fats, tank bottoms,
emulsions, and oily sludge from wastewater treatment.
Two alternatives exist for oily waste management: (1) reclaim
the oily wastes; (2) place the oily wastes in holding tanks until a
buyer can be found through a waste exchange. Of these alterna-
tives, recommending the implementation of a waste oil recovery
operation would be the most environmentally sound.
Each unit operation removes contaminants of a certain sort;
these are as follows:17
1. Gross water, coarse solids and other materials heavier than
oils, i.e., BS and W (settleable materials).
2. Light ends, naptha and water i.e., relatively volatile mate-
rials.
3. Acidic compounds, additives and contaminants stabilized
in solution and suspension (includes nitrogen, sulfur, oxy-
gen and metal-containing organic compounds).
4. Odor and color bodies.
5. Suspended and colloidal solids.
Since in any waste oil re-refining scheme, each of the above
contaminants must be addressed, no single unit operation can
provide complete processing. Settling removes BS and W. Strip-
ping covers the second category, adsorbent treatment the third
(to a limited extent), and solvent extraction and filtration the
fourth and fifth. Chemical treatment and fractionation will
improve waste oil recovery17.
The proposed waste oil re-refining process, therefore,
involves two basic process trains:
1. adsorption/filtration
2. solvent extraction/ fractionation
These two trains can be termed adsorbent treatment and sol-
vent treatment, respectively.
The waste oil reclamation process produces 86 tons per day
product oil, 43 tons per day overheads, and one ton per day light
ends. In the process, 2.4 tons per day additives, 44 tons per day
solvent, and one ton per day adsorbent slurry are used as raw
materials. However, the process also produces 10 tons per day
bottom sludges and water, 5 tons per day naptha and light ends,
3-5 tons per day bottoms, and 0.3 tons per day adsorbant/ oil
mix. These waste products may be routed to the incinerator at
the central facility for combustion and ultimate disposal.
Costs are presented in Table VII.
Waste Solvents (B1-B4)
Waste solvents (BI-B4) will be produced in relatively small
quantities (less than 15 kkg/day) in Allegheny County by 1985.
Over 50% of these solvents are produced in the PPG works in
Creighton. PPg is planning to install a solvent recovery unit in
the near future to recycle their in-plant waste solvents.
In this light, two management alternatives exist: (1) design
and build a solvent recovery unit, or (2) transport waste solvents
to PPG for solvent recovery via a waste exchange. The second
alternative is best, but these wastes may not be compatible for
recovery by the PPG system.
In the event of non-acceptability by PPG, several solvent rec-
overy systems were investigated. Solvent recovery generally
consists of two unit operations. An evaporator acts as a distilla-
tion unit to fractionate the solvent into its respective compo-
nents or respective feed stream solvents at different tempera-
tures. Sludges are produced by this process, as not all solvent
feed streams are impure when they enter the process. The vapor
from the process is condensed to produce product solvent.
Generally, 75% of the waste solvent will be product solvent. The
self-conta'ned solvent reclamation systems investigated con-
tained an evaporator, condenser, water separator, vacuum-
liquid pump, and heat source (when needed). These systems are
shipped ready to operate, with all elements mounted on some
form of platform, ready to be connected to electric, water, and
steam lines. A range of sizes exists on the market. Solvent recov-
ery systems can be obtained for sizes ranging from 7.5 to 1,000
gallons per hour.
For Allegheny County, a system size of 4.5 kkg/day or 50gal-
lons/ hour would be suitable. Costs are given in Table VII.
The recovered solvent's actual value varies considerably with
the type of solvent, the size and type of reclaiming process, the
degree of purity of the product, and the general economic cli-
mate of the time and place in which it is being sold. Generally,
the value of reclaimed solvent is closely tied to the value of the
original product (virgin material) and will sell for from 50 to
90% of the value of the original solvent. Although prices range
from 20« to $10 per gallon, most of the reclaimed solvents will
sell at the lower end of the scale.
OTHER PROCESSES
Scrubber Sludges (D6) and Flue Gas Desulfurization
(FGD) Sludges (E4)
Scrubber sludges (D6) from air pollution control processes
such as baghouses and flue gas cleaning and desulfurization
sludges (E4) together comprise 14% of the total Allegheny
county residue production in 1983. Most FGD sludges involve
some fly ash disposal as well, so they are more correctly termed
flue gas cleaning (FGC) wastes.
Of the two management alternatives available, (1) landfilling
or (2) landfilling using a chemical stabilization process, the sec-
ond may be more environmentally sound.
Three different chemical sludge fixation processes were
reviewed.18,19,20 Operating costs (1976) range from $7.30 to
$ 11.40 per dry ton for chemical fixation and landfill 5 miles from
the site of generation.21 Cost data is difficult to obtain for the
three specific processes currently available because of: (l)equip-
ment specialization and variability, (2) proprietary nature of
chemical additives. Varying load factors and land costs also
make cost determinations difficult, but computed costs for
sludge fixation appear in Table XI.
Electromagnetic Metal Recovery
At present, iron slag generated within the County is being
recycled by the Duquesne Slag Company (Pittsburgh). There is
uncertainty as to whether a heavy media magnetic metal separa-
-------
Allegheny County—II 275
tion process can economically recover heavy metals in the Coun-
ty's steel slag, air pollution control residues from foundries, mill
scale, and air pollution dust to warrant its implementation. Pre-
liminary cost estimates are presented in Table XI.22
Brick Production Process
Approximately 1856 kkg per day of cement dust (E6), cullet-
glass production slag (E5), and fly ash (E8) will be produced
daily in Allegheny County by 1983. A technical alternative for
the resource recovery of these wastes is a new brick-making pro-
cess which has been developed over the last 10 years in Morgan-
town, West Virginia, by the University of West Virginia in con-
junction with the Office of Coal Research of the Bureau of
M ines.25 The fly ash-to-brick plant takes ash and converts it into
building bricks by a shuttle kiln method. This method was inves-
tigated to see if wastes from Allegheny County could be used as
raw materials.
Costs for the plant are given in Table XI. For a plant to use
930 tons per day of materials, it would produce approximately
584,000 bricks per day at 3.5 pounds per average brick.24 The
cost of the plant would be approximately $8,360,000 assuming
linearity (1976 dollars).24 However, sale of the 584,000 bricks per
day would yield a total credit of $16,640,000 yearly. The plant
would be assumed to operate 7 days per week in 3 shifts per day.
Shuttle kilns are used, reducing costs. The additives are sodium
silicate and water and energy for the gas-fired shuttle kiln.
Energy costs amount to approximately $2 million per year.
However, brick production would be approximately equal to
5-10% of the entire U.S. brick production; it is doubtful that
these bricks could be sold in Western Pennsylvania. A packing
cost is included in the operating and maintenance costs of the
facility. On a smaller scale, this type of operation may be feasible
for private industry. Data are included in Table XI.
REFERENCES
1. EPA, Public Affairs Office. "Hazardous Wastes and their
Management." U.S. EPA, Washington, D.C. May, 1975.
2. A. K. Vitberg, M. L. Rucker, andC. H. Porter. Implement-
ins "Best Management Practices"for Residuals: The Waste
Exchange. U.S. EPA 440/9-76-019, Washington, D.C.
June, 1976.
3. St. Louis Regional Commerce and Growth Association.
"St Louis Industrial Waste Exchange: Operations and
Procedures". (The Exchange). 1975.
4. M. Tapperson. Press Release by the Saint Louis Regional
Commerce and Growth Association, St. Louis, Missouri.
May 5, 1976.
5. Personal Communication with Mr. John Lehman, EPA
Office of Solid Waste Management Planning. March 4,
1977.
6. P. Henriken, "One Private Plant Treats Oil, Chemical
Residues in Denmark." Solid Wastes Management Maga-
zine. May, 1974 Reprint.
7. C. Ris, "Visit to Treatment Plant Constructed by PEC
Engineering, Hambourg, France." EPA Memorandum to
File. Feb. 19, 1975.
8. J. M. Montgomery, Inc. Preliminary Planning Step for the
EPA I VRCSD R, D&D Project for Residual Waste Man-
agement. Pasadena, California. Augmentation to Feb. 19,
1974 proposal.
9 Arthur D. Little, Inc. Waste Clearinghouses and
Exchanges: New Ways for Identifying and Transferring
Reusable Industrial Process Wastes. NTIS No. PB-261-
287. Cambridge, Massachusetts. October, 1976.
10. D. D. Spatz. "Reclaiming Valuable Metal Wastes." Pollu-
tion Engineering. January - February, 1972.
11. Battelle Laboratories. Recovery of Metal Values from
Metal Finishing Wastes. EPA Project No. R803787. (EPA
Draft Report). Columbus, Ohio. 1976.
12. Personal Correspondence with Mr. Richard D. Billmyre,
Vice President Engineering, Crown Environmental Control
Systems, Inc. Indianapolis, Indiana. October 28, 1976.
13. American Public Works Association, Refuse Collection
Practice. Interstate Printers: Danville, Illinois. 1966.
14. T. Fields and A. W. Lindsey, Landfill Disposal of Hazard-
ous Wastes: A Review of Literature and Known
Approaches. EPA -OSWAMP 530/SW - 165. September,
1975.
15. G. D. Gumtz. Restoration of Beaches Contaminated by Oil.
EPA Publication R2-72-045. Philadelphia, Pennsylvania.
Sept, 1972.
16. L. W. Weinberger. "Oil Reuse - A National Need." Pro-
ceedings of the International Conference on Waste Oil Rec-
overy and Reuse. Washington, D.C. February 12-14,1974.
(Proceedings Reprinted by Information Transfer Inc.,
Rockville, Maryland).
17. Environmental Quality Systems, Inc. State of Maryland
Waste Oil Recovery and Reuse Program. EPA Grant S-
800650. Edison, New Jersey. November, 1973.
18. The Aerospace Corp. Control of Waste and Water Pollu-
tion from Power Plant Flue Gas Cleaning Systems: First
Annual R&D Report. EPA -600/7 - 76-018. Research Tri-
angle Park, N.C. October, 1976.
19. J. W. Jones. "Alternatives for Disposal of Flue Gas Clean-
ing Wastes". EPA. Research Triangle Park, N.C. (19777).
20. U.S. Environmental Protection Agency. Sulfur Oxide
Throwaway Sludge Evaluation Panel (SOTSEP), Volume
II: Final Report - Technical Discussion. EPA No. 21ACY -
030. NERC, Research Triangle Park, N.C. April, 1975.
21 R. B. Fling, et. al Disposal of Flue Gas Cleaning Wastes:
EPA Shawnee Field Evaluation Initial Report. EPA 600/ 2
- 76.-070. PB- 251876. March 1976.
22. Private Communication with Mr. Robert Blunkosky, Pro-
ject Manager, MEPS, Inc. Carnegie, Pennsylvania.
November 3, 1976.
23. C. F. Cockrelland H. E. Shafer, Jr. A Technical Evaluation
of the WVU - OCR Process for Producing Fly Ash - Based
Structural Materials. Coal Research Bureau Report No. 40.
West Virginia University at Morgantown, W. Va. 1969.
24. K. E. Humphreys, Operating and Capital Costs of Produc-
ing Fired Structural Products from Waste Coal Ash. Coal
Research Bureau Report No. 98. West Virginia University
at Morgantown, W. Va. 1974.
25. Personal Communication with Mr. Jim Newburn of the
John Zinc Co., Tulsa, Oklahoma. October 28, 1976.
26. E. J. Martin and D. L. Guthrie. Projection Methodologies
for Flows, Loads and Residues. Paper presented at 3rd
National 208 Planning and Implementation Conferences.
Reston, Va, Denver, lo, and St. Louis, Mo. March, April,
May, 1977.
27. Engineering - Science, Inc. Sludge Processing, Transporta-
tion and Disposal I Resource Recovery: A Planning Pers-
pective. EPA No. WPD 12-75-01. NTIS No. PB 251 -013.
U.S. Environmental Protection Agency, Washington, D.C.
December 1975. p93.
28. T. Fields and A. Lindsey, Landfill Disposal of Hazardous
Wastes: A Review of Literature and Known Approaches.
EPA No. SW - 165. U.S. Environmental Protection
Agency, Washington, D.C. June 1975, plO.
-------
The Generation and
Disposal of
Hazardous Wastes
in Massachusetts
INTRODUCTION
Hazardous wastes management has aroused the concern of
both industry and government. The recent passage of the Re-
source Conservation and Recovery Act of 1976 focused national
attention on this problem and provides a framework for state
and federal action. Among the act's provisions is the require-
ment that each state develop a hazardous waste management
plan, the first step of which is a hazardous waste inventory. The
Commonwealth of Massachusetts has made a significant head
start in this direction. Since 1970, Massachusetts has had a
hazardous waste regulatory program and has recently com-
pleted a statewide hazardous waste inventory. The purpose of
the paper is to review briefly the current hazardous waste regu-
latory program in Massachusetts, and to describe the approach
taken and the results uncovered during our hazardous waste
inventory. Based on our experience in this work, we also provide
recommendations for improved hazardous waste management
as required under the new Resource Recovery Act.
Regulation of Hazardous Waste in Massachusetts
Legislation to control the handlingand disposal of hazardous
wastes was adopted in Massachusetts in 1970. This law estab-
lished a Hazardous Waste Board, comprised of the members of
the Water Resources Commission and the Commissioner of the
Department of Public Safety, and designated the Division of
Water Pollution Control to administer the regulations adopted
by the Board.
Assignment of hazardous waste responsibility to the state's
water pollution control agency traces back to earlier programs
which the Division of Water Pollution Control initiated in 1968
and 1969 aimed at the prevention and control of oil pollution
and which included a licensing requirement for waste oil
collectors. Collection and disposal of waste oils was subse-
quently incorporated into the new hazardous waste regu-
lations, and in fact, waste oils still comprise the largest volume of
hazardous materials covered by the regulations.
The regulations: define wastes that are considered hazardous,
specify methods for the handling and disposal of such materials
and require that any firm engaged in their conveyance, handling
or disposal be licensed by the Division of Water Pollution
Control.
The Massachusetts regulations do not contain an itemized list
of specific materials by their chemical names, but rather define
"hazardous wastes" as any " . . .waste substances which,
276
Paul F. Fennelly, Mary Anne
Chillingworth, Peter D. Spawn,
and Mark I. Bornstein
GCA Corporation
Bedford, Massachusetts
and
Hans I. Bonne, Glen Gilmore
Massachusetts Division of
Water Pollution Control
Boston, Massachusetts
because of their chemical, flammable, explosive, or other
characteristics constitute or may reasonably be expected to
constitute a danger to the public health, safety, or welfare or to
the environment." Further, the regulations establish categories
of hazardous materials and describe in broad terms allowable
disposal methods for each category.
The categories are arranged into four classes—Hydrocarbon
Liquids, Aqueous Liquids, Solids and Sludges, and Special
Hazards—typical subdivisions of which include waste oils,
solvents and chlorinated oils, plating and pickling waste, metal
hydroxide sludges, oily solids, explosives, reactive metals,
pesticides, waste cylinders of gas, and other compounds
assigned a hazard rating of No. 2 or greater in the National Fire
Prevention Association identification system. To date, this
manner of definition and classification has proven adequate in
bringing those materials needing special control under the legal
authority of the regulations.
The Division's licensing activities include review of applica-
tions, inspection of equipment and disposal sites, and monitor-
ing of operating reports, which each collector or disposal facility
must submit on a monthly basis. As many disposal methods are
subject to air quality standards or rules regulating the operation
of sanitary landfills, there exists a strong need for coordination
with other state agencies. In addition, the regulations require
that any disposal of wastes outside of Massachusetts be
approved by the appropriate environmental agency of the
receiving state.
Licenses, which must be renewed annually, specify which
types of materials may be handled, and indicate whether
licensing is for conveyance, storage, disposal, or any combina-
tion of these. Currently, about 100 firms hold Massachusetts
hazardous waste licenses. Over half of these provide only
collection of wastes, or collection and storage only, and must
rely on other licensed firms for ultimate disposal. Approxi-
mately 20 of the licensed companies are located out-of-state.
Most of these offer final disposal for one or more categories of
waste.
Two factors have limited the effectiveness of the hazardous
waste program in the past. The first has been lack of sufficient
manpower to ensure strict enforcement of the rules. Recent
reassignment of Division personnel to hazardous wastes and the
creation of two new engineering positions under a grant from
the Environmental Protection Agency's Solid Waste Manage-
ment Program have significantly improved this situation.
Between the Division's central office in Boston and its three
-------
Massachusetts Program 277
regional offices, the total professional activity directed toward
hazardous wastes in fiscal 1977 will be 6 man-years.
The second, and more important problem is the lack of
suitable disposal options within Massachusetts for certain types
of wastes, particularly hazardous solids and sludges which
require a secure chemical landfill. Reasons for this lack include:
(1) limited private investment due partly to previous weak en-
forcement, (2) absence of an extensive chemical process industry
to provide the base load for a major facility, and (3) disunity
among state regulatory and management agencies. The net
result has been economic hardships to industry caused by long
distance transportation costs and incentive for some industries
to use illegal or questionable disposal methods.
As a first step towards resolution of the problem, Control in
1976 engaged GCA/Technology Division to perform a hazard-
ous waste survey and to recommend methods of hazardous
waste managemanagement.
Hazardous Waste Survey
The primary effort in the survey was to improve the data base
with respect to hazardous wastes in Massachusetts. Using the
improved data base, recommendations could then be made for
improved hazardous waste management.
This project was designed to satisfy three major objectives:
• Estimate the quantities of hazardous waste—using a
telephone survey in conjunction with personal visits to
selected industries, estimates were to be made of the amounts
and geographic distribution of the various categories of
hazardous wastes generated in Massachusetts.
• Identify disposal and recycling options—in conjunction with
the survey, a search was also made to identify options
available for improving the present manner of disposing of
hazardous wastes.
• Recommend disposal options—based on the above informa-
tion, recommendations for optimum disposal practices were
to be made on an immediate (3 months to 1 year) and long-
term (1 to 5 years) basis.
Estimate Hazardous Waste Quantities
The first step in this project was to review the Division of
Water Pollution Control's files containing the annual permit
applications and monthly reports from the waste haulers
licensed and operating in Massachusetts. The data from the
permit files provide a lower limit with which to compare the
results of the next phase of the project, a survey of Massachu-
setts industries with respect to their quantity and disposal
methods of hazardous wastes.
Review State Permit Files
For each licensee, the quantities of each class of hazardous
waste handled in 1975 were obtained by adding the amounts
reported for each month. Table 1 summarizes these findings.
For consistency, all reporting units were converted to gallons. A
major problem encountered in reviewing the hazardous waste
files in their present form is that the origin of the wastes is almost
never reported and the delivery to another licensee or to a
recycling/disposal facility may not be specified on each monthly
report. Rather, many monthly reports state that the wastes will
be delivered to any of several alternatives which are listed on
their annual permit applications. Such a system hinders the
tracing of many individual waste streams; nevertheless, using
the available data, best estimates for the disposal/ recycling fates
of the five classes of hazardous wastes are also displayed in
Table I. These figures suffer from the fact that some licensed
haulers deliver their pickups to other licensed handlers, thus
causing some wastes to be counted twice.
Of the 13,329,000 gallons of waste oil picked up, approxi-
mately 6,917,000 gallons, or 52 percent are burned, either as fuel
or in an incinerator. Another 1,715,000 gallons, or 13 percent,
are used for dust control on roads and 486,000 gallons (4 per-
cent) are delivered to asphalt plants. Only 3,046,000 gallons or
23 percent are reclaimed, while 500,000 gallons or 4 percent are
landfilled. The landfilled oils are primarily derived from spills
and usually contain the absorbing media. Solvents are reclaimed
(59 percent), burned (9 percent) or landfilled (1 percent). Most
of the 783,000 gallons (30 percent) which is not accounted for is
solvent sludge or distillation bottoms which is incinerated or
landfilled. Most of the aqueous chemicals picked up are treated
and then discharged to the sewer. A small percentage (0.5 per-
cent) are reported being buried directly in a landfill. Solids and
sludges are landfilled (56 percent), or in the case of sludges from
oil tanks or solvent reclamation, burned (41 percent). Of the
1,620,000 gallons of hazardous materials reported as being
hauled to landfills, 503,910 (31 percent) are taken out-of-state,
primarily to New Jersey landfills; 713,000(44 percent) gallons of
hazardous wastes were disposed of in Massachusetts landfills
which today are not licensed to accept these wastes. (No new
licenses were awarded to any Massachusetts landfills in 1975
and 1976.)
Survey of Massachusetts Industries
To supplement the data in the hazardous waste files and to
provide a better understanding of the flow of hazardous wastes
within Massachusetts, a survey of the amount, geographic dis-
tribution and current practices of hazardous waste disposal was
Table I: Summary of Hazardous Waste Volumes Reported by Massachusetts Licensed Haulers in 1975, gallons/year
Disposal method
Hazardous
waste
Wastewater
treatment
Asphalt
plants
Picked up
Delivered
Difference
Reclaimed
Burned
Landfill
Dust Control
Other
Waste oil
13,329,000
12,664,000
665,000
3,046,000
6,917,000
500,000
1,715,000
486,000
Solvents
2,602,000
1,819,000
783,000
1,544,000
223,000
34,000
18,000
Aqueous
liquids
2,009,000
1,847,000
162,000
10,000
1,830,000
7,000
Solids and
sludges
834,000
1,804,000
-970,000
740,000
1,009,000
55,000
Other
144,000
145,000
-1,000
78,000
67,000
Total
18,918,000
18,279,000
4,590,000
7,958,000
1,620,000
1,715,000
1,830,000
486,000
80,000
-------
278 Massachusetts Program
organized.
The first step was to identify the types of industries which
would be expected to generate hazardous wastes. After a review
of the technical literature and discussions with the state and
federal regulating agencies, the industries shown in Table 11
were selected for the survey. The Massachusetts Industrial
Directory 1974-1975, which lists industries by Standard Indus-
trial Classification (SIC), was used to identify the companies
and number of employees within each selected SIC.
To speed the flow of information, contacts were made
primarily by telephone. Using a telephone survey form devel-
oped byGCA, the plant manager or the environmental engineer
from each facility was questioned about the types of wastes
generated by his plant. Several industries were reluctant to
release what they considered to be proprietary information but
were willing to discuss their wastes in terms of broad classes,
such as waste oils, solvents, acid, sludges, etc.
The response of most of the individuals contacted during the
survey was very cooperative; less than 1 percent of those
contacted refused to participate in the survey in any manner. In
all, 446 plants completed the questionnaire. These account for
9.2 percent of the 4,868 plants listed in the industrial categories
selected for this survey and represent 45.4 percent of the
employees in these industries. Ninety-one plants were either
unable to estimate waste quantities or could not be contacted in
follow-up calls.
Table II: Major SIC Categories Expected to Generate Hazard-
ous Wastes
Industry
Textile alii produces (dyeing and finishing only)
Paper and allied products
Printing, publishing, and allied Industries
Chemicals and allied products
Petroleuo refining and related industries
Rubber and miscellaneous products
Leather and leather produces
Primary metal industries
Fabricated metal products except machinery and transportation
equipment
Machinery, except electrical
Electrical and electronic machinery equipment and supplies
Transportation equipment
Measuring, analysing, and controlling instruments? photographs!
medical, and optical goods* watches and clocks |
Miscellaneous manufacturing industries
Most of the information provided to the survey team repre-
sents a "best guess" by the plant manager or the plant's environ-
mental engineer. In many cases, the exact quantities of wastes
generated were unknown, but waste volume were estimated
based on factors such as number of pickups per year, size of
storage tanks, and quantities of new materials used.
The data collected during the survey were extrapolated to
yield statewide totals on the basis of number of employees in
each industrial category. In order to represent the industries as
accurately as possible, these extrapolations were performed at
the 3-or4-digit SIC level. This assumed that all industries within
each 3- or 4-digit category were engaged in the same types of
operations and would therefore have similar types and
quantities of wastes.
The extrapolation procedure also assumes a linear relation-
ship between wastes generated and number of employees. This
may introduce a source of error as plants with large numbers of
employees may have only a small number engaged in produc-
tion activities and smaller plants may use different
manufacturing processes than larger plants. The estimates
presented here are best treated as lower limits, accurate
probably to within a factor of 2 or 3.
The major part of our survey dealt with hazardous waste
material from manufacturing (or related) industries, but also
included in the project were surveys of special classes of
hazardous wastes such as automotive waste oil, fly ash from
power plants, polychlorinated biphenyls (PCB's) and pesticides.
These wastes were estated from published and unpublished
generation factors and discussions with key industrial and regu-
latory officials.
In all, 37,750,000 gallons of hazardous wastes are generated
each year in Massachusetts. Of this, 18.5 million gallons are
waste oil, 9.2 million gallons are sludges, 4.0 million gallons are
plating wastes and metal containing sludges, 2.7 million gallons
are solvents, 2.3 million gallons are acids and alkalis and 0.8
million gallons are other hazardous wastes. Table 111 summa-
rizes the distribution of hazardous waste among the various
sources. Waste oils from automobiles account for 83 percent of
the state's total waste oil. Fabricated metal products and
machinery are the major industrial sources, contributing 9 per-
cent.
Solvents are used primarily by the Electronics Industry, SIC
36, and by miscellaneous industries such as jewelry and
silverware manufacturers, SIC 39. Approximately 41 percent of
Table III: The Distribution of Hazardous Wastes among Various Industrial Categories
Typ« of laduatrr
ra*«r ud alliod product
1)0 UWI
Ijj laalhM
fiotuec
, clay, |1|H. tO»-
cr«t« pro4i»«ta
u rrtmn !¦*»•**»••
Patrick**
WcbtMtr.
llW[rhil «arf
imU Mchla*n
32 l'«
JT Tim
u Hn«—oMlyflM
aed «s*troUl»t
I?,**)
U.S47
I,W
13.a"
4.401
ut
4.4*1
II,1*'
».»>
ft.MO
13,2*1
5,711
JlS.40*
10.•"
11.fcfll
J).711
11,771
2,S»7
J),03»
3S.10*
It)
U.W
U.OM
M.S"
u.«2
40.«•
II.»"
Nrcaai
r»p# of (loHam/vaar)
474,104
W.fc
4».2
O.T
*1.0
».4
14.•
*1.0
nt
si i
« »
47.?
~J.J
no
i.nvi.jio
u,no/Jo,uo
'o.Dom.no
Jt.Ud/si.no
JJ0/44C
a/no
4S3,ttS/4«l,4M
M.OOO/IH.TOO
M.MS/103.*41
27.J0O/74.J4O
2.410/1),141
143.'31/241.2)0
J7.7TS/J0.470
2.4H/4.47S
614,440/121,020
PL«t lag WMtt
mi aatal
1,44*.m/2,
2«2,«ai/l.044,2>0|
7)7.770/1.001.40),
M4.V10/M2.4M
24I.Ottfm.Hl
*•.)»/•0.02*
• .4»m.»*
2,23),14*/S,ona)t)
440/1.37*
12t.M>/MS.49)
13,710/4*.»71
I.74J/14.1JO
4».m/«l.M0
MS/1.3IQ
tj.rit/iM.tos
2M.m/m,Ms
2.0l».*45/4,OJS.USi
W).440/0.4*7. W
27,MO/42,240
M,4J)/I),4M
1)0,010/1,424,240
24,040/47,m
14},nO/24S.4SO
lS.4M/<«vlL5
>M.)2)/2,292.7)0
OlMr
MMrtMl
•MM*
2,2)*/3.4lO
t.MS/11,09)
1)1.470/444,1)0
u.oivn.tK
14S/SS0
47.220/17,JIO
))2,3)0/7)), "X
100,4)0/21), MO
IM.420/U1.441
100,320/219.OSS
:.4ll,M0/S,7OI,m
2.142.2*0/2.««7,)M
2**,7*0/121,070
441.04*/!,U),7*0
CD
•7»,1«/3,0M.)J)
1,442,441/2.00J,71}
1.115,MO/2.09O.M)
441,471/1,2M,M)
147,)4)/Ml.7U
i.oa,»*o/i.4)j,ijj
110,440/m.ttt
U1S*ltflS/I1.174,t|S
27-0
11,2
Shf uml"""' r*p«rnd (or
tf^ eieeeUwowe alai** nyrf < 1*
Ste rtmft"'"! ll^l* ra#ort«4 (or
ni. -, Mo.iroA.iM.'" Mi/n. »
,M, — ».«i.'*"'.'"."1 """¦
U.L „..r»7 ~
.11 .1 .... -...Ul I. M« — -t
,1 ,H at IU. HUrUl 1, twn M.
K «11 «f thU MM, 1,1 1, 1m,< • kMrAl
-------
Massachusetts Program 279
the total state solvent waste is generated by these two industrial
classifications.
As anticipated, metal sludges and plating wastes are gener-
ated primarily by three industries: Primary Metals, Fabricated
Metal Products and Machinery, Except Electrical. The com-
bined waste from these three classes is approximately 71 per-
cent of the total metal sludge and plating waste in the Common-
wealth.
Acid and alkali wastes are produced almost solely from the
primary metals industry, which produces approximately 80 per-
cent of the state total for this type of waste. These reactive
materials are used for cleaning and plating metals.
Miscellaneous sludges are mostly comprised of wastes from
the chemical industry. They contain numerous types of organic
and inorganic components and account for 60 percent of the
miscellaneous hazardous sludges generated in the state. Paper,
printing, and textile industries generate large quantities of
sludge, but it was not generally considered hazardous.
The last major category. Other Hazardous Waste, represents
undefined wastes reported during the survey, as well as wastes
that do not fit into the other five categories. Almost 60 percent of
these wastes are generated by the chemical industry. Fabricated
metals, electrical equipment, and miscellaneous manufacturing
industries together generate 34 percent of the unclassified wastes
which may include photographic chemicals, resins, inks, and
polymer solutions. Most of the "Other Hazardous Wastes,"
which are derived from the paper and printing industries, are
waste inks.
In Table IV, the survey results are compared with the state
permit data. The last column in the table provides the percent-
age of the hazardous types which the state has identified through
its permit system. Note that the first three categories maintain a
high profile—waste oils and solvents, because of their current
value, and aqueous liquids because of the relative ease of
handling and disposal. The problems in regulating sludge and
other types of waste are self-evident.
Figure 1 shows the geographic distribution of hazardous
wastes generated throughout the Commonwealth on a county-
wide basis. Not unexpectedly, the metropolitan areas around
Boston, Worcester, Springfield and New Bedford have the
greatest quantities.
Table IV: Comparison of Survey Results with Licensed Hauler
Permit Data—gal/yr
Waste material
Survey results
Permit data
Percentage
Identified
permit data
Waste oil
18,313,000
13,329,000
73
Solvents
2,784,000
2,602,000
93
Aqueous liquids
2,293,000®
2,009,000
88
Solids and sludges
13,928,OOOb
834,000
6
Other
756,000
144,000
19
38,074,000
18,918,000
50
Acids and alkalies only.
^Includes plating solutions (770,000 gallons).
Several states have published the results of their hazardous
waste surveys. Table 5 compares our survey results with those
obtained in five other states. Surprisingly close correlation is
found with Arizona, Minnesota, Oregon and Washington in the
ratio of industrial wastes to manufacturing employees, despite
differences in the mix of industries. Maryland, however, a
heavily industrialized state with a large chemical industry, far
exceeds these ratios.
A?"-
B MtMKT
C Wtu. um aatm
0 iMCCLLAMOUl SLUM!
E AQO ALKALI
OTIC* HAZAM0US MSTI
AUTO **n OH.
Figure 1: Geographic Distribution of Hazardous Wastes in Massachusetts
-------
280 Massachusetts Program
Table V: Comparison of Massachusetts Survey Results with
A. Industrial Wastes
State
Industrial
hazardous
wastes,
gal/yr
Number of
manufacturing
employees
Ratio of
industrial waste
to number of
manufacturing
etnployee8»
gal/y*"-Person
Massachusetts
Arizona
Maryland
Minnesota
Oregon
Washington
2?., 135,000
12,387,000
565,700,000
11,886,000
7,717,000
13,390,000
618,000
(1,460 manufacturers)
230,000
343,000
197,000
252,000
36
2460
35
39
53
B. Automotive Waste Oil
State
Massachusetts
Minnesota
Oregon
Automot ive
waste oil,
gal/yt
15,435,000
6,000,000
8,004,000
Population
5,800,000
1,914,000®
2,219,000
Per capita
automotive waste oil,
gal/yr-person
2.7
3.1
3.6
a1970 population for the eight counties surveyed.
Disposal and Recycling Options
Existing Capacity
The severity of the hazardous waste disposal problem is most
evident with respect to sludges—there are no disposal sites
within the state which are currently licensed to accept these
materials. Some of these materials are being shipped to out-of-
state disposal sites or waste recycling/disposal firms as shown in
Figure 2, but most are either being temporarily stored in
company facilities or disposed of illegally. Because of the
tlltM-ftm or «MTI« MOCtMM
0 TIMinll trATION
X «A«TI oik
O '
0 All. cot
A mvtar
Figure 2: Disposal Options for Massachusetts Industrial Wastes
distances involved, out-of-state shipment is economically prac-
tical only for large quantities of wastes. The survey confirmed
the difficulties that small waste generating industries have in
disposing their waste sludges.
Many sludges could be landfilled within the Commonwealth
if an acceptable site were available and licensed. GCA's survey
indicated that a total of approximately 13 million gallons of
potentially hazardous industrial waste sludges are generated per
year. If these sludges (assumed to contain 10 percent solids) were
dewatered to an 18 percent solids concentration (as required for
disposal of municipal treatment sludges to conventional land-
fills), the resulting sludge volume would be on the order of 1.0
million cubic feet (7.2 million gallons). This volume of sludge
would only occupy about 1 acre per year, if landfilled to a depth
of 20 feet (no allowance for earth fill or cover). This indicates
that small sections of existing landfills, if modified for accepting
hazardous waste, would be adequate, at least over the next 1 to 5
years until new facilities can be built.
With respect to solvents and waste oils, for which the
preferred disposal method is reclamation or reprocessing, the
capacity of Massachusetts firms alone is not sufficient to handle
the quantities of waste materials generated within the state. For
solvents, an estimated 2.8 million gallons a year are generated,
while in-state reclamation capacity is on the order of 1.3 million
gallons a year. Similarly, annual waste oil generation is
estimated at 18 million gallon/year compared to an in-state
reprocessing capacity of about 5 million gallons annually.
Despite this excess of waste oil and solvents, local reprocessors
are still running considerably under capacity due to competition
for waste oil and solvents from rerefiners in other states as
shown in Figure 2, as well as from firms who burn waste oil
directly as a fuel or apply it for dust control. More than 70
percent of the waste oil and solvents are disposal of in an
acceptable manner. The current economic value of these wastes
probably goes far in explaining their relatively high pickup rate.
Transfer Stations
Most of the sites shown in Figure 2 are running well below
capacity despite the strong need for adequate disposal facilities.
One of the primary reasons for this is the cost of transportation.
The smaller waste generators simply can not afford to ship to
some of these facilities. A potential solution which has much
potential for alleviating the waste disposal problem is the devel-
opment of private industrial transfer stations. A transfer station
is a centrally-located area which receives, for a fee, wastes from
surrounding industries. When a truckload of economic size
(usually 2,000 to 4,000 gallons bulk) has accumulated, wastes
are removed to the out-of-state disposal firms by an independent
hauler or by the disposal firms themselves. Two private transfer
stations have recently begun operating in Massachusetts and the
initial response looks very promising. In addition, a private
waste exchange brokerage offers industry a service to facilitate
the use of one industry's wastes as feedstock for another
industry.
Recommendations for Improved
Hazardous Waste Handling
and Disposal
Concerted action must be taken with respect to the manage-
ment of hazardous waste disposal. In Massachusetts the sev-
erity of the problem is most evident with respect to hazardous
sludges—there are no landfills within the state which are now
licensed to accept these materials. Some of these materials are
being shipped to out-of-state disposal sites, some are being
temporarily stored in company facilities, but considerable
amounts are being disposed of improperly and illegally. The
following recommendations have been made to improve control
-------
Massachusetts Program 281
of hazardous waste disposal in Massachusetts. The state must
continue to refine its approach to hazardous waste manage-
ment. The new Resource Recovery Act calls for the devel-
opment of statewide hazardous waste management plans, but in
many cases, the implementation of these plans will require leg-
islative changes which can sometimes be painfully slow.
To alleviate the problem, action is required on two levels:
steps which can be implemented immediately (i.e., 3 months to 1
year) and steps which can be implemented over a longer range
(i.e., 1 to 3 years). Each are discussed below.
Recommendations for Immediate Action
• Consolidate Authority for the Hazardous Waste Program.
The regulation of hazardous waste will often cut across air,
water and solid waste regulatory agencies; often each will
have its own regulatory approach and order of priorities.
Within one of these agencies, a single section should be
designated as having overall responsibility for hazardous
waste management, planning, and enforcement. In Massa-
chusetts this section should be placed within the Division of
Water Pollution Control, which currently has the broadest
authority within existing state agencies with respect to
hazardous waste regulation.
• Modify Several Existing Landfills to Accept Hazardous
Waste. Modification of several existing landfills to accept
hazardous wastes is essential to relieve the current lack of
state approved disposal sites. One potential site is a private
landfill in eastern Massachusetts, which is lined with a
relatively impervious material and fitted with a leachate
monitoring and collection system. Initial contacts have been
made with the owners by the state concerning possible
adaptation of this landfill for certain hazardous wastes.
Action along these lines should be accelerated. In addition,
other landfills in the state should be evaluated as soon as
possible as potential hazardous waste disposal sites.
• Enforce Existing Hazardous Wastes Regulations More
Strictly. Strict enforcement of hazardous waste regulations,
assuming that disposal sites become available, is the key to
improving hazardous waste disposal. Strict enforcement of
existing regulations would reduce illegal and
environmentally-unacceptable disposal of wastes and stimu-
late the private waste disposal/recycling industry by guaran-
teeing a market for disposal services.
• Encourage Use of Transfer Stations. Many companies that
generate small amounts of hazardous waste are reluctant to
use out-of-state reclamation/disposal services because of the
high unit costs associated with handling and transporting
small quantities of waste. A solution to this problem is the
transfer station concept where a centrally-located storage
area receives wastes from surrounding industries. When a
truckload of an economic size (usually 80 drums, or 2 to 4,000
gallons bulk) has accumulated, wastes are removed to the out-
of-state disposal firms by an independent hauler, or by the
disposal firms themselves. (Since the completion of this
report, at least two firms are now operating as transfer
stations for hazardous waste disposal in Massachusetts.)
• Promote Better Waste Oil Disposal Practices. Presently
waste oil collectors in Massachusetts are selling collected oils
for road oil, fuel oil, and asphalt manufacture. About 52 per-
cent is burned, 23 percent rerefined (or reclaimed), and 13 per-
cent used for road oiling. The optimum disposal method is
rerefining and it should be encouraged wherever possible.
Burning waste oil without removing contaminants can result
in significant emissions of lead and other heavy metals, and
road oiling can result in significant environmental contamina-
tion, as EPA tests indicate that 70 to 90 percent of untreated
waste oil applied to a road is reentrained to the atmosphere
(on dust particles) or surface water (via runoff)- It is recog-
nized that each of these practices may be acceptable in certain
limited locations, but in general they should be phased out.
• Develop Public Relations and Educational Programs. An
important step should be an educational and public relations
campaign geared toward plant engineers and plant managers
(especially in small to medium-size plants) to publicize the
regulations; to define hazardous wastes; and to indicate
proper waste handling methods.
Long- Term Recommendations
• The basic long-term recommendation is to develop a state-
wide hazardous waste management plan as required by the
Resource Recovery Act. This would address topics such as
number and type of waste facilities needed, criteria for
disposal site selection, schedule for developing new facilities,
manpower requirements for increased enforcement, etc. As
part of this management plan, a stricter enforcement program
should be focused around a waste manifest system which
requires waste generators, haulers and disposers to file
monthly reports on their hazardous waste quantities, destina-
tion and final disposal.
-------
Development of a Regional
Industrial Waste
Treatment Facility
Walter J. Bishop,
Ronald J. Calkins and
Joseph Borgerding
Ventura Regional County
Sanitation District
Ventura, California
INTRODUCTION
Industries throughout the country are facing increasingly
tighter restrictions on the type of materials that they can
discharge to publicly owned municipal sewers or to navigable
waters. Revenue recovery programs and pretreatment require-
ments may make joint industrial/municipal treatment too
expensive for continued discharge to the sewer. To assist the
industries of Ventura County, California, in effectively dispos-
ing of these wastes, the Ventura Regional County Sanitation
District initiated a project to provide a centralized regional
facility for treating industrial residual wastes. The proposed
facility will be centrally located in the county and will accept
trucked wastes consisting of industrial pretreatment residues
which are generated as local industrial source control programs
are implemented.
The purpose of this paper is to trace the development of a
regional industrial waste treatment facility for Ventura County,
California. Under the direction of the Ventura Regional County
Sanitation District and in cooperation with an EPA research de-
velopment grant, the study was undertaken to identify the
residual wastes generated by industries located in Ventura
County and to propose treatment processes to adequately
handle the wastes. This paper will be organized in the following
manner: First, information will be provided which will give a
background on Ventura Regional County Sanitation District,
the area and environment of Ventura County, and the type of
users to which the facility will serve. Secondly, the history of the
project from the early development stages up to the current
progress will be presented. Thirdly, a description of the actual
project which will include the type of processes proposed, the
phasing of the project development, the experimentation and
research which developed these processes, costs of implementa-
tion, construction and operation of the plant, as well as
anticipated plans for the future will be included. The goal of this
paper is to provide the reader with a case history on how a
regional approach is being used to solve industrial waste
problems in Ventura County, California.
Project Background
The Ventura Regional County Sanitation District is located
in Ventura County, northern neighbor of Los Angeles County in
Southern California. The boundaries of the Regional District
are contiguous with those of Ventura County and include an
area of 1,800 square miles and a population of 440,000 (see
Figure 1). The Regional District was formed in 1970 by
resolution of the County Board of Supervisors to provide a co-
ordinated approach to the problems of liquid and solid waste
disposal. The District's governing body is composed of elected
officials from the County of Ventura, nine incorporated cities,
and the 16 special sanitary districts within the county. The
purpose of the Regional District, as adopted by the Board of
Directors, is to satisfy within the available powers and policies
the waste disposal needs of the member agencies and public
when called upon to do so. This includes planning, construction
and operation of liquid and solid waste facilities in the county.
The environmental setting of the Regional District's service
area is a rather unique one relative to its close proximity to the
Greater Los Angeles Metropolitan Area. The primary industry
of Ventura County is agricultural, as it is one of the leading pro-
ducers of citrus and vegetable food crops in the country. In
addition, the oil fields comprise the second largest industry in
the county. Specific industrial activities consist of citrus and
vegetable packing, meat and fish processing, chemical suppliers,
ferrous and nonferrous metal works, aircraft support industries,
paper products, as well as typical support industries found in
most urban areas. The historically rural setting of Ventura
County is starting to disappear as development pressures from
the Los Angeles area begin to reach further outward. Industries
from Los Angeles are beginning to locate in and among the nine
incorporated cities of the county, requiring greater planning and
awareness of their disposal needs by the responsible agencies.
In California, and in other states, all discharges to navigable
waters must meet standards as specified in the Federal NPDES
permit. The State of California was the first state designated by
EPA to administer the NPDES permit program. Under this
designation, California has developed and established its own
discharge standards which are incorporated into the permit. As
a result, treatment plants in California must meet more stringent
discharge requirements than as provided by other federal regu-
lations. For example, the following limits must be met by a local
wastewater treatment plant:
BOD 20 mg/1
Suspended Solids 15 mg/1
Oil & Grease 10 mg/1
Arsenic 0.01 mg/i
Cadmium 0.02 mg/1
Total Chromium 0.005 mg/1
Copper 0.2 mg/1
Lead 0.1 mg/l
Mercury 0.001 mg/1
Nickel 0.1 mg/l
Silver 0.02 mg/i
Zinc 0.3 mg/l
Cyanide 0.1 mg/l
Phenols 0.1 mg/l
Totafl Identifiable Chlorinated itydnocartjons o. 002 mg/1
282
-------
Regional Facility 283
-------
284 Regional Facility
EXISTING CLASS I DISPOSAL SITES
1. Pacific Reclamation and Disposal Site
2. Sierra Reclamation and Disposal Site
3. West Contra Costa Disposal Site
4. Big Blue Hills Disposal Site
5. Casmalia Disposal Site
6. Simi Valley Landfill
7. Calabasas Landfill
8. West Covina Landfill
g. Palo Verdes Landfill
10. Otay Landfill
11. Omar Rendering Company Disposal Facility
IM IMIIIt
7) (£}
?y *<
«•-
(io)&u
Figure 2: Existing Class 1 Disposal Sites
-------
Regional Facility 285
These discharge limits severely increase the need for
pretreatment by industries, and increases the amount of residu-
als which must be removed from industrial wastewater dis-
charges. The only acceptable means of disposing of these wastes
in Ventura County consists of landfilling.
The Regional District, as part of its responsibilities, operates
the county solid waste disposal facilities. In the rural and
changing setting of Ventura County, the primary solid waste
disposal facilities utilize the technique of landfilling. The State
of California has devised a system for categorizing its landfills,
i.e., as Class I, Class 11, and Class 111. Class 111 landfills only
accept inert materials while Class II landfills can accept
domestic rubbish. Class I landfill sites refer to those underlined
with an impermeable membrane to eliminate the possibility of
leaching toxic materials into the groundwater. These types of
landfills are capable of receiving all wastes with the exception of
radioactive materials. Such sites are usually the primary
receivers of toxic wastes trucked in from industrial sources. As
environmental concerns continue to increase, the availability
and acceptability of new Class 1 sites in Ventura County and the
State of California as a whole are becoming very difficult
situations to deal with. The threat of depletion of available Class
I sites, and the steady increase in the number and size of
industries relocating to Ventura County, prompted the initia-
tion of a survey in 1972 by the Regional District to determine
what the waste needs of the county's industries might be. At that
time, it was determined that many industries were facing a
situation of no longer being able to discharge certain materials
into publicly owned treatment works and municipal sewers.
State as well as federal regulations were being adopted which
prohibited the discharge of noncompatible materials either
directly to navigable waters, or to publicly owned municipal
systems.
For other wastes, revenue recovery programs and pretreat-
ment requirements have the potential for making joint industri-
al/municipal treatment too expensive for continued discharge
to the sewer. Based on the information gathered in our door-to-
door survey, and utilizing the discharge requirements, and
pretreatment regulations of the State and EPA, a projection was
made of the residual waste materials that would have to be
removed from municipal treatment systems (see Table 1). In
addition to these materials, the amount of other residuals which
were currently being landfilled, yet could be more effectively
disposed of by another treatment process, were included in the
final projections of wastes which could be expected at a
centralized residual waste treatment facility.
As previously mentioned, current residual waste disposal as
practiced in California relies almost exclusively on landfilling.
Unquestioned use of this as a disposal method is no longer the
case. As an example of the lack of current disposal capacities
and the need for more facilities, Figure 2 shows the available
Class I landfill sites in the state. Any wastes of potentially
hazardous or toxic nature must be disposed of at these special
landfills which are geographically and geologically isolated
from usable groundwaters. The relatively few sites available
throughout the state, the rapidly diminishing capacities of the
sites, and the prospect for new sites becoming indeterminant,
identified a need for alternative solutions in this area. One
approach which appears to have promise in the Ventura County
area is a centralized treatment facility which will handle trucked
residual wastes.
The Ventura Regional County Sanitation District, with the
assistance of the EPA, is studying the use of a treatment facility
which has the ability to detoxify residual wastes so that they may
be easily disposed of in one of the many Class II landfills, or as a
minimum requirement, concentrated to use less of the remaining
Class I space. In the consideration of the alternatives which can
satisfy these requirements, a price tag that does not impose
extreme hardship on industrial users was included.
Table I: Summary of RWTF Projected Wastes
DESIGNATED W$m
NEAR-TERM PROJECTIONS
Gal/Day
Gal/Mth
Gal/Day
Gal/Mth
Metallic Wastes
250
5,500
6,450
141,900
Nonmetallic Toxins
750
16,500
6,000
132,000
Brines
3,000
66,000
8,000
176,000
Oil & Grease
500
11,000
5,550
122,100
TOTALS
4,500
99,000
26,000
572,000
Holding Capacity
10,000
50,000
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286 Regional Facility
Project Development
Concept Development
After the completion of the 1972 residual waste survey, the
Ventura Regional County Sanitation District proposed the de-
velopment of a waste treatment facility which could handle
residual wastes for the county. Based on data collected concern-
ing the type and quantity of wastes available in the county,
residuals were subdivided into five categories. These categories
were heavy metal wastes, nonmetallic toxic wastes, oils and
greases, brine wastes, and organic wastes. A project proposal
was submitted to EPA's Kerr Research Laboratory in Ada,
Oklahoma, and was awarded a research grant under the joint
industrial/municipal treatment and control program. As out-
lined in the EPA proposal, Ventura County contains a variety
of diverse residual wastes from activities related to citrus and
vegetable packing, meat and fish processing, chemical suppliers,
petroleum products, metal works, aircraft support industries,
paper products, as well as typical support industries found in
most urban areas. Because this is one of the fastest growing
counties in California, early development of a comprehensive
residual waste management program was deemed essential.
Also, because of its proximity to the Los Angeles Metropolitan
Area, any project demonstration of such management may
prove applicable on a much larger scale in that neighboring
region. The proposed work as called for under the conditions of
the EPA grant consisted of dividing the project into three
phases.
Phase I: Phase I consists primarily of the planning leading up
to and including pilot plant studies. The preliminary planning
work included the development of the research outline, identifi-
cation of quantities and types of wastes which would be treated,
literature search and selection of the proposed treatment
processes, and final preparation of a project budget. Pilot plant
studies were conducted on wastes and processes identified in the
preliminary planning stage. The pilot plant studies involved
preparation of a testing program for production of design
parameters fundamental to Phase II work.
Phase II: Phase 11 consists of facility design and construction.
This involves the implementation of design criteria established
under Phase I in preparation of construction plans and specifi-
cations. The construction of the facility will be supervised,
inspected and completed under this phase.
Phase III: Phase III consists of operation of the facility for a
one-year period and final report preparation. The operation of
the facility will determine the best methods for management of
the regional waste facility, as well as the economics of treating
the various classes of wastes. The final report will consider and
evaluate: (1) economics of the process, including the costs of
design, construction, operation, as well as user costs; (2) residual
treatment management; (3) local community interaction with
the facility; (4) interaction of local industries with the facility; (5)
projection of residuals produced within the service area; and (6)
the impact of pollution control regulations, both state and
federal.
As called for under the E PA grant, Phase I, design costs under
Phase II and Phase III were funded up to $350,000. The
soliciting of construction funds are the responsibility of Phase I
work. This consists of the preliminary planning identified under
Phase I, the identification of the particular industrial waste
residuals, which have to be treated, the identification of the
discharge requirements for such a facility; selection of treatment
flow schemes; estimates of the potential funding requirements of
such a process; on-site sampling of particular industrial wastes,
characterization of these wastes, treatability studies of these
wastes; testing bench scale processes; and a final report which
recommends the type of treatment facility proposed for design
and construction. The following discussion presents the findings
of the bench scale study which was conducted on the particular
wastes of Ventura County utilizing specific treatment processes
as envisioned for this treatment plant.
Bench Scale Testing
As determined in the Regional District's industrial waste
survey in 1972 and in subsequent followup surveys in 1974 and
1976, the specif ic quantities and types of wastes which required
residual waste treatment had been identified. As previously
mentioned. Table 1 summarizes the results of the waste survey.
The decision was made to treat the residuals to a level whereby
they could be discharged to a publicly owned treatment works.
1 he next step in the design of the facility was the determination
of the methods for treating these wastes to that level. As
envisioned, the facility would accept trucked residual wastes
brought to the site for treatment and ultimate discharge.
Residual wastes brought to the facility would be segregated into
five categories, namely heavy metals, nonmetallic toxins, brines,
oils and greases, and organic wastes. The residuals would be
subjected to the combination of treatment processes which
would adequately prepare the wastes for safe ultimate disposal.
Since waste production and handling are not subject to the same
degree of control as a manufacturing process, it was anticipated
that the composition of the wastes in any one category would
vary considerably, and some intermixing of categories would
occasionally occur. For this reason, it was decided that all waste
streams must be subject to frequent physical inspection, with
provision for rapid chemical testing to verify suspect contamina-
tion of one class of waste for substances which may render the
entire batch unsuitable for eventual disposal at the intended site.
The presence of unwanted or interfering substances in any class
of waste may make a particular treatment process less effective
than another. To determine which of several processes pro-
duced the most consistent results over a significant operating
period, it was desirable to try a number of possible processes on
a pilot scale basis using typical wastes from each category.
The following process characteristics were considered in the
selection of the unit processes and treatment schemes for the
residual waste treatment facility:
1. Safety
2. Reliability
3. Minimization of waste products
4. Minimization of energy and chemicals required for treat-
ment
5. Ability to handle a range of types and concentrations of
wastes
6. Maximization of reclaimable products
Each of the wastes received at the central facility would fall
into one of the five categories: oily wastes, brines, heavy metal
wastes, nonmetallic toxins, or organic wastes. Oily wastes
coming to the facility would consist mostly of residual petro-
leum which is normally found in tank sumpings, oil field sludge,
and oil saturated materials from accidental spills of petroleum
production operations. Many residual oil wastes are now
collected and reclaimed; however, significant quantities still find
their way onto the land.
Metal wastes will come primarily from metal plating, etching,
cleaning, and finishing operations. Principal contaminants were
identified as copper, zinc, chromium, cadmium, nickel and tin.
Cyanides, although not metallic in nature, are contained in
metal processing plants because they are normally used as
complexing agents in the metal plating process. Other toxic
metals df concern are the salts of lead, used in pottery glazes;
mercury, used in herbicides and disinfectants; and the various
elements used in paints and glazing pigments. Nitrate, hydro-
floric, hydrochloric, and sulfuric acids, sodium hydroxide,
ammonia and trisodium phosphates are also considered in this
class because they arc common occurrences in metal cleaning,
-------
Regional Facility 287
HbtVYMHALS »A«Tl
Figure 3: Treatment Facility Schematic
carboxylic ion exchange step was found even more effective
downstream of the sequence of hydroxide and sulfide
precipitation as a final polishing step. Metal sulfide precipi-
tation in the presence of added ferrous iron is extremely
convenient and effective when carried out in the same
reaction vessel in the presence of hydroxide precipitates. For
this reason, it is suggested that carboxylic ion exchange not
be used in this treatment sequence.
4. The most difficult operation for handling cyanide wastes is
the oxidation of complex nickel cyanides. A long exposure
time requiring as much as eight hours is needed with sodium
hypochloride dosage in order to completely oxidize cyanides.
Neither the sulfide precipitation step or the carboxylic ion
exchange, or a combination of the two, will remove nickel
adequately if the complexes are inadequately oxidized.
5. The problem of receiving wastes that may contain ammonia,
chrome in the hexavalent state, and cyanides requires that all
metal wastes be treated to remove cyanides and reduce
chromium whether or not it is believed they are present. This
problem can easily be solved; however, waste containing
large portions of cyanide must be segregated from acid
wastes for reasons of safety.
6. In this study it was found that foam fractionization was not
as effective for separating soluble nonmetallic toxic substan-
ces as was coagulation in the presence of a suitable polyelec-
trolyte followed by dualmedia filtration and carbon absorp-
tion. Foam fractionization is not attractive because it (1) may
pollute the atmosphere; (2) the need for providing a liquid
spray to collapse the float produces another liquid effluent
that must be dealt with; and (3) is not as effective as the
coagulation filtration sequence.
7. The use of filtration (anthricite and sand) removed a higher
proportion of particulate matter when used downstream of
the coagulation processes. It was found that the use of
activated carbon above the sand to replace the anthricite in
the case of the proposed plant was not likely to be cost
effective.
8. Generation of sulfide sludge and hydroxide sludge in the
same reactor rather than separate vessels produced a sludge
that easily settled and dewatered and the supernatant
contained less residual soluble heavy metals than if the
hydroxide sludges were removed first.
Plant Design Considerations
Based on the bench scale studies conducted, the following
design considerations were derived:
1. Due to the relatively small volume of each type of industrial
waste anticipated, and the need for segregation of these
wastes, tanks, equipment and unit processes will be dupli-
cated where possible and sized such that their combined
capacities can handle design flows.
2. The requirement to interchange units to handle waste
loadings; the need for uninterrupted operations during
future expansions; and the desire to minimize costs of
expansion require that piping and equipment arrangements
provide maximum flexibility in the operation.
3. Optional reclamation processes (namely ion exchange soft-
ening and reverse osmosis) have not been included in the
design considerations. If reclamation of the final process
water or if certain treatment difficulties arise on wastes con-
sidered in this study, then these options can be considered at
a later time.
4. The residual waste treatment facility would require slightly
less than one acre of land.
Operational Considerations
As presently envisioned, trucks would unload immediately
upon arrival at the facility, and their wastes would be discharged
by gravity into one of four 10,000-gallon holding tanks.
Characterization tests would be performed on the wastes to
determine the appropriate treatment processes to employ. The
wastes would then be pumped into the appropriate treatment/
storage tanks and treatment could begin. At any time,
treatment could be terminated and tanks drained by gravity into
one of the four holding tanks. These wastes could subsequently
be pumped into another processing unit or back to trucks for
disposal at a Class I facility. All tanks would be constructed of
corrosion resistant materials, most likely lined with reinforced
-------
288 Regional Facility
Table II: Kstimated Capital Costs
No,
r
2
3
6
7
3
9
Item
Description
Storage and process tanks (circular)
G - 10,000 gal
2 - 6,000 gal
2 - 5,000 gal
H - M00 gal
Sludge concentration and handling
Dissolved air floatation
Dual media filters and carbon sorption
Chemical storage and feed systems
Site work, concrete pads, structures
Misc, mechanical equipment, piping,
transfer; and process pumps
Control building (lab, storage, etc,)
Electrical, instrumentation, panels
Subtotal
Contingencies (15%)
Construction cost
Engineering, legal, admin, (20%)
Total
aNovember 1976 costs (ENR = 2915)
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Regional Facility 289
etching and degreasing operations. The heavy metals waste
category was subdivided into cyanide wastes, ammonia wastes,
chromate, and heavy metal wastes without cyanide or ammonia.
Brine wastes, characterized by the high concentration of total
dissolved solids, contain waste products from water softening
operations, oil field operations, and citrus packing houses which
use soda ash solutions for decay control.
Nonmetallic toxic substances are compounds such as phen-
ols, creasote, formaldehyde, and various chlorinated hydrocar-
bons used as insect and pest controls. Although small amounts
might be received at full strength as tank drainage or condemned
stock, it is anticipated that most of these materials will be well
diluted with fresh water as with container flushings or equip-
ment washings. Substantial amounts of fertilizer and pesticides
are used in the county in support of the enormous agricultural
industry. Significant quantities of these substances have been
identified as requiring some method of disposal.
The organic wastes are primarily from the cannery and fro-
zen food processing industries, manures from animal holding
operations and feed lots, sewage sludge from municipal waste-
water plants, meat and fish processing wastes, and wastes from
paper processing operations. Consideration is being given for
treating these organic wastes at this facility by the use of
pyrolysis which is the subject of a study to be done in
conjunction with the Jet Propulsion Laboratory in Pasadena.
When the complexity and extreme cost of solving the organic
waste problem became evident, the project was divided into two
parts to allow work on the four liquid streams to proceed inde-
pendently of the organic waste testing. The following section
discusses the results of the Bertch Scale Testing Program which
has been completed on wastes from the first four categories.
Bench scale testing of the pyrolysis process on local organic
wastes should proceed through 1977. The remainder of this pa-
per will deal with the development of the residual waste
treatment facility to treat the four liquid waste streams.
Process Development
A number of various treatment schemes have been proposed
for each waste category to be processed at the proposed facility.
These process schemes have been modified or replaced over the
course of the study to adequately handle the specific wastes
found in Ventura County. The following is a brief discussion of
the process schematics which have been proposed for each of the
four liquid waste categories. As previously discussed, the fifth
category, organic wastes, is being studied as part of a different
project.
Essentially two waste alternative treatment schemes have
been proposed for the metallic waste category, ion exchange and
chemical precipitation. The first alternative scheme envisioned
the use of carbon adsorption for removal of organic wetting and
complexing agents. A sodium cation exchange unit would
follow to remove the metallic ions while the cyanide normally
present in metallic wastes would be removed in a hydrodoxl
anion exchanger. The concentrated metals removed during
regeneration would go to a Class I landfill. The second alterna-
tive proposed for treatment of metallic wastes utilized chemical
precipitation. Experience with plating and printed circuit board
etching industries indicates a strong probability of ammonia
compounds used as etchants being present in metallic wastes.
These ammonia wastes contain strong oxidizing agents. It is also
essential that wastes containing cyanide compounds not be
mixed with low pH solutions such as those containing chro-
mium. Therefore, the second alternative recommended that
heavy metal wastes be categorized into three subcategories: (1)
cyanide wastes; (2) chromate and/or other heavy metal wastes
without cyanide or free ammonia; and (3) ammonia wastes.
Oxidation of cyanides occurs with the use of chlorine or sodium
hypochloride. These wastes would then be combined with other
wastes containing heavy metals and a sequence of hydroxide
precipitation in conjunction with sulfide precipitation was
proposed to remove the metals. Sulfide precipitation with its
very low solubility was proposed to meet very low concentration
levels of metals prior to discharge to publicly owned treatment
works. In both alternatives, chemical coagulation followed by
multimedia filtration was recommended to assist in reducing
turbidity levels.
Treatment schemes proposed for the nonmetallic toxic wastes
involved the use of dissolved air floatation or foam
fractionization-floatation. Either one of these processes would
clean up the waste prior to the use of carbon adsorption which
would be the actual removal mechanism for the nonmetallic
toxins. As an alternative to this treatment sequence, chemical
coagulation followed by sedimentation was proposed in place of
the dissolved air floatation process. Carbon adsorption, howev-
er, would still be used for actual removal of the nonmetallic
toxins. Reverse osmosis was included as an option to both al-
ternatives if water reclamation was desired. The major question,
therefore, in treating of the nonmetallic toxic wastes involved
the selection of either the foam fractionization-floatation or
dissolved air floatation units versus the use of chemical coagula-
tion and sedimentation for cleanup prior to the use of carbon
adsorption.
The treatment scheme proposed for the oily waste category
consisted of gross removal of oils using an API or similar type
separator followed by a dissolved air floatation unit for cleaning
the wastes to meet strict discharge specifications. This particular
process could be altered by using the addition of a decantation
or skimming tank prior to the API separator. The two major
alternatives to be considered in this treatment scheme were the
use of either the dissolved air floatation unit or the foam frac-
tionization-floatation unit for cleaning up the waste following
gross oil removal.
For brine wastes, one of the treatment schemes proposed
consisted of the use of gross oil removal followed by polymer
addition and dissolved air floatation. The proximity of the site
to the ocean eliminates the need for removal of dissolved
minerals. The alternative for this method was the use of
fractionization-floatation using a detergent and polymer addi-
tion followed by carbon adsorption and ocean disposal.
In order to determine the best alternative for each treatment
scheme, a recently completed bench scale testing program was
initiated. The following processes were evaluated on a bench
scale level: metal hydroxide/sulfide precipita'tion, carboxylic
ion exchange, dissolved air floatation, foam fractionization-
floatation, multimedia filtration, carbon adsorption, tube
settling, sludge thickening, and sludge dewatering techniques.
Typical wastes from a variety of industries in the county were
collected and treated with the bench scale units. Types of
industries sampled included metal platers, electronic circuit
board printers, metal recyclers, machinists (cutting oils), fertil-
izer and pesticide applicators (washout), plastic manufacturers,
and gas producers.
As shown in the attached flow schematic (Figure 3), the
results of the testing program recommended the type of
treatment schemes which performed adequately on the sampled
wastes. The following operational and design conclusions were
developed based on the bench scale testing program.
1. The hydroxide and sulfide precipitation sequence, including
the segregation and destruction of cyanide wastes, proved to
be an effective method of treating a variety of wastes that
contained cyanides and toxic heavy metals.
2. The presence of iron in the ferrous state when precipitating
residual heavy metals with sulfide enhances the degree of
removal of the metals.
3. Carboxylic ion exchange instead of the metal sulfide precipi-
tation is also effective but not as attractive as the latter. The
-------
290 Regional Facility
Table III: Operating Costs
fiberglass. Tank bottoms would be conical or hopper shaped to
eliminate expensive sludge scraper mechanisms. As conceptual-
ized, the design includes an on-site laboratory facility which will
enable rapid characterization of the wastes and monitoring of
the progress and efficiency of the treatment methods.
Cost Estimates
Itemized descriptions and estimates for capital and operation
& maintenance costs are given in Tables II and III: The
estimated construction cost total of $ 1.2 million includes money
for extensive earth work and laboratory facilities. The operation
and maintenance costs were difficult to calculate because of the
unknown quantity of chemicals required to effectively treat
certain wastes, and the indefinite quantities of wastes which
might be brought to the facility. As presently conceived, the
residual waste treatment facility would be operated by two
personnel on a 5-day-per-week, eight-hour-per-day basis. The
positions would require a highly competent operator as well as a
chemist with extensive experience with industrial wastes.
Treating residual wastes is extremely complicated and a lack of
knowledge could easily be fatal when dealing with such wastes as
cyanides.
As estimated, the operational costs per thousand gallons can
range trom $17 to approximately $40 depending on the volume
of wastes received. The $17 figure would be for receipt of
approximately 30,000 gallons per day, whereas the $40 figure
would represent the cost for a 5,000-gallon-per-day operation.
As previously mentioned, one of the goals of the project is to
provide a treatment facility at a cost within a range of the current
costs of landfill disposal. Currently, hazardous wastes in
Ventura County are disposed of at a rate of $8.50 per ton to a
Class 1 landfill. Converting the above-mentioned operational
costs to a tonnage basis, the operational costs at the proposed
facility are on the order of $4 to $ 10 per ton. Even without con-
sidering the advantage of a central location and lower hauling
costs, the proposed plant appears competitive with present
landfill disposal charges.
Future Planning
The residual waste treatment facility is currently in the design
and construction phase (Phase 11). The selection of a consultant
for preparation of construction plans and specifications has
been completed, and design will begin shortly. The current EPA
research grant does not provide funds for construction of the
facility; however, the project has been placed on the State of
California's Clean Water Grant List, and has received favorable
consideration for receiving federal funding under Section 201 of
P.L. 92-500 during fiscal year 1977-78. The current project
activity schedule envisions a six-month design period with the
plant being on-line in approximately one and a half years. The
EPA research grant will cover the costs of operation for the ini-
tial year, and the subsequent years' operation costs are antici-
pated to be charged to the plant's users.
In the future, many industries will find themselves in the
position of no longer being able to discharge certain materials
into the sewers. Future state and federal regulations and, in
particular, new pretreatment regulations will prohibit discharge
of some of these materials. For other wastes, the use of sanitary
landfills may no longer be an available option. The residual
waste treatment facility as proposed for Ventura County will
supply a local service which can have nationally significant
impact as the results of the program are evaluated.
CATEGORY
' 1 vEAftLY Cusl
5,000 gpd 30.000 spd
1,
Labor
$ 26,000
$ t)5.500
2.
Chemicals
6,400
40,000
3,
Maintenance
7,000
20,000
4,
Utilities
6.000
12,000
5.
Miscellaneous
5,000
10,000
TOTALS
$ 50,400
$127,500
UNIT COSTS:
$/Ton
$/!., OOQ Gal
$ 9,50
'10.00
$ 4.00
17.00
-------
A Viable Design for
a Regional Industrial
Waste Treatment Facility Bruno Loran
The Ralph M. Parsons Company
Pasadena, California
INTRODUCTION
A number of procedures are currently available for the
disposal of industrial wastes. We are concerned here with either
"hazardous" or high concentration industrial residuals. The
procedures commonly followed will be briefly reviewed, starting
from the least complex and least costly.
At present, most industrial wastes are disposed of in landfills.
A "Class 1" landfill is required, where no possibility of
groundwater contamination by leachates exists. Usually, sepa-
rate areas are provided for acid and alkaline wastes, and often
the wastes are disposed of in wells dug into the compacted
refuse. Organic wastes are spread on loose soil, which has a high
absorption capacity: in a few hours, few traces of liquid are
visible at the surface, and a new load can be spread. When the
soil becomes saturated, it is covered with a new layer of soil
scraped from the hillside; the landfill is now ready for new loads
of organics, or a layer of municipal refuse can be interposed. If
the soil contains moisture and the temperature is above freezing,
bacterial action can decompose a large fraction of the wastes.
Landfill areas in the proximity of urban industrial centers are
becoming exhausted, but in many cities 30 to 50 year capacities
are not uncommon. Due to increasing environmental concern
for groundwater contamination and for socioeconomic factors,
very few permits for new Class 1 landfills are granted. In
addition, suitable sites for "secure" landfills may not be
available in geographical areas featuring a high groundwater
table or lacking the correct geological formations.
A second alternative for liquid industrial wastes is sewer
disposal. However, the public agencies in charge of sewer
systems exhibit today much less latitude in accepting industrial
loads. The Federal government is now directly involved through
the Water Treatment Grant Program; compulsory industrial
charges are required, and industries have to meet pretreatment
standards meant to protect the wastewater treatment plant from
upsets or high pollutant loads.
A third course is open to industry: improve housekeeping
practices and manufact uring processes with the aim of decreas-
ing the amount of wastes produced. This course of action is
often financially advantageous to the industry concerned
because it leads to a more efficient use of resources. However,
these practices decrease the amount of wastes generated but still
leave a remainder to be disposed of. Individual waste treatment
facilities may still be required: there are advantages in in-plant
treatment, because the wastes treated have a fairly constant
composition, and some of the products obtained may be
reusable in-house. However, small size companies may not be
able to afford individual waste treatment facilities, and larger
industries may have to build treatment plants which are not eco-
nomically efficient because of less than optimum size or
intermittent operation.
Regional Industrial Waste Treatment
Treatment of industrial wastes at a regional facility is the most
complex and, under most circumstances, the most expensive
disposal procedure. However, as discussed above, in some
instances it may represent the desirable course of action. The
fact that heterogeneous wastes are received makes regional
treatment a very difficult task. The main criteria to be met are:
• Safety
• Effective treatment for all wastes
• Reasonable cost
The Ralph M. Parsons Company recently reviewed the design
of a regional industrial waste treatment facility for the City of
Sydney, Australia, and had considerable previous experience
with the design of individual waste treatment systems. We are
presenting here our conclusions concerning the design of a
viable regional industrial waste treatment facility.
Waste Characteristics
What types of wastes can we expect to be received at the gates
of the facility? Typically, most wastes will be received in the
liquid or slurry phase; the wastes can be divided into four major
groups having approximately equal volumes, and consisting of:
1. Aqueous Inorganic Wastes
Acid wastes (sulfuric, nitric, phosphoric, chromic,
hydrochloric, other)
Alkaline wastes
Neutral salts
Plating wastes (dilute cyanide, other)
2. Aqueous High BOD Organic Wastes
Animal
Vegetable
Grease-trap wastes
3. Non-Aqueous Organic Wastes, Recyclable
Solvents, chlorinated
Solvents, non-chlorinated
Waste mineral oil
4. Non-Aqueous Organic Wastes, Non-Recyclable
Paints and resins
Chlorinated organics
Non-chlorinated organics
Rubber latex
Concentrated cyanides
The selection of these four groups reflects our design philo-
sophy, aimed at an integrated waste treatment facility providing
291
-------
292 Design for a Facility
t %
>:
S3
Si
3
-------
Design for a Facility 293
ranges from pure liquids to thick slurries; the only limitation is
material too coarse in size to be fluidized or having a large ash
content with a lower melting point than the temperature of the
sand bed. The fluidized bed serves as a large heat reservoir where
rapid mixing of the waste throughout the bed provides efficient
contact between the waste particles and oxygen and levels out
the impact of sudden feed changes or variations in fuel value.
Different wastes may be introduced at the same time at different
levels in the bed according to their calorific value; aqueous
wastes may be in-roduced above the bed to evaporate part of the
water by heat transfer with the hot gases. No pre-blending of the
wastes is required; this is impossible, at any rate, in many
instances. For example, varnish wastes precipitate on mixing
with hydrocarbon solvents. Only one control is required: the
maintenance of a constant bed temperature (usually 1400° F); in
most units this is achieved automatically.
It is clear from these descriptions that the only single
incinerator capable of combusting all the wastes contemplated
for a regional industrial waste treatment facility is a fluidized
bed incinerator. The other alternative is the use of a fixed
chamber incinerator and a rotary kiln.
Chlorinated hydrocarbons require custom incineration due to
their higher decomposition temperatures and the corrosive flue
gas produced. A fixed chamber incinerator run at higher
temperatures (up to 2600° F if polychlorinated biphenyls are
included) is recommended. The incinerator will require special
refractory lining and an air scrubber capable of handling the
highly corrosive effluent gas generated; the scrubber section
may cost more than the incinerator itself. The hydrochloric acid
generated may be recovered as such, treated with lime to
generate calcium chloride useful as road-salt, orelectrolyzed to
produce chlorine gas, which can be utilized in-house for the
oxidation of dilute cyanides.
Concentrated cyanides can also be conveniently disposed of
by coincineration with waste oil in a fixed chamber incinerator.
A temperature of 2200-2300° F is required, and lining of the
incinerator with chrome-magnesite brick to prevent the forma-
tion of eutectics with sodium is recommended.
Recycling
Recycling operations are often the key to the successful
operation of a regional industrial waste treatment facility.
Operational, maintenance, and capital amortization expenses
can dictate user charges which would be prohibitively expensive
for industrial users. Recycling and resale of reclaimed products
can recover part of the expenses; recycling is also within the
spirit of the Federal Resource Conservation and Recovery Act.
Three major classes of compounds lend themselves to recy-
cling:
Chlorinated solvents
Non-chlorinated solvents
Waste mineral oils
The products are listed in the order of decreasing resale price.
Solvents and oils can be recovered from solutions or thin slurries
using distillation columns of the type used in oil refineries. Thick
slurries or tars require a wiped film evaporator, operating at
reduced pressure.
Knowledge of the waste characteristics, supplied by the
originerators, will be very helpful. Sometimes the products
recovered can be sold back to the waste originators; at any rate,
the suppliers of these valuable materials would not be charged
for their disposal.
Safety
Safety is one of the most important aspects in the operation of
a regional treatment facility. Each waste is a single chemical
entity, most often highly charged with chemical energy. Con-
stant alertness is required to avoid disastrous consequences,
such as highly exothermic reactions between concentrated acids
and bases, or release of hydrogen cyanide on accidental
acidification of cyanide wastes.
A facility of this kind requires a meticulous design effort,
covering such disparate subjects as personnel safety, spill
avoidance, segregated storage, line cross-over safeguards,
selection of construction materials, secured ultimate disposal,
and handling of contaminated stormwater runoff.
Personnel safety is addressed in a comprehensive EPA report
on the management of hazardous wastes.1 The procedures rec-
ommended include:
• Equipment of unloading facilities with catchment basins in
case any material is accidentally spilled during the unloading
and transfer operation.
• Clear definition of work procedures, including those for
emergency operations in case of accidents.
• Equipment of work areas with emergency and safety
equipment and apparel for employees, including safety
showers, independent breathing air masks, chemical and fire
resistant clothing, various fire fighting devices, and alarm
systems to warn of hazardous conditions in the work areas.
• Provision of in-plant safety devices including systems
which can detect erroneous transfers of material and auto-
matically shut down transfer pumps, if necessary.
SUMMARY
After a brief review of current industrial waste disposal
procedures, we present the design of a regional industrial waste
treatment facility concentrating on hazardous wastes or wastes
featuring high pollutant loads.
The wastes received are divided into four groups: aqueous
inorganic wastes, aqueous high BOD organic wastes, non-
aqueous recyclable organic wastes, and non-aqueous non-
recyclable organic wastes.
The integrated waste treatment facility planned features three
main treatment sections: a physico-chemical section, where
most aqueous wastes are detoxified, a distillation section, where
many organic materials are purified for recycling, and an
incineration section for the disposal of non-reusable organics.
Mutual detoxification and interactive disposal are applied to
a great extent, as in co-neutralization of acidic and alkaline
wastes, interactive oxidation-reduction of chromic and ferrous
wastes, and co-incineration of high-Btu nonreclaimable organic
materials with high BOD organic wastes, such as meat-packing
wastes or concentrated cyanides. Recovery by distillation and
resale of organic solvents and mineral oils are employed; this
practice can be the key to a successful financial operation.
Safety considerations are one of the most important aspects
to be considered. Pertinent design items and recommended
practices are listed.
REFERENCE
1. Battelle Memorial Institute, "Program for the Management
of Hazardous Wastes", EPA Report 350/SW54, 1974,
available from the National Technical Information Service
as PB-233 630 (Volume 1) and PB-233 631 (Volume 2).
-------
EPA's Combined Wastes
Program Residual
Management Studies
Thomas E. Short, Jr.
Robert S. Kerr Environmental Research
Laboratory
Ada, Oklahoma
INTRODUCTION
The principal philosophy of the combined Industrial Pro-
gram is that many industrial wastes problems can be solved
more effectively on an area-wide basis. The advantages of this
approach are based largely upon the favorable economies of
scale that exist when a single facility is utilized to treat wastes
from many sources. Additionally, combinations of wastes offer
other advantages. An individual waste could contain materials
that interfere with biological activity in a treatment system.
When it is combined with other wastes the concentration of
these materials could be diluted to "sub-toxic" levels. Also high-
strength wastes can be combined with low-strength wastes in a
manner such that the resulting concentration levels can be
treated much more effectively. Combinations of acid wastes
with caustic wastes can result in "neutralization" of the resulting
waste. If the wastes from a variety of industrial sources are
compatible, and if transportation of these.wastes can be eco-
nomically achieved, then, by far, it is much less costly to treat
these wastes in one large treatment plant. Compared to the cost
of treating each individual waste source at a large number of
small individual plants, area-wide treatment facilities can be
very economical. For those industries which have wastes that
are compatible with domestic wastes, discharge to and treat-
ment in municipal sewage treatment plants offer a highly
effective areawide solution. Discharge into municipal systems
could be effective for those industries that can pretreat their
wastes so as to make them compatible with domestic wastes.
The Combined Wastes Research Program is unique among
EPA industrial environmental research efforts in that it is
concerned with the control of point sources of wastes, on an
area-wide rather than individual basis. As such, this program is
involved in wastes from all types of industries plus wastes of a
domestic origin. This program deals with such problems as the
establishment of centralized facilities to treat refractory indus-
trial wastes generated within a defined geographical boundary,
pretreatment of industrial waste prior to discharge into a pub-
licly owned treatment plant, and the areawide management and
disposal of industrial residuals.
This paper will summarize results from two typical projects
undertaken by the Combined Wastes Program. The first was an
EPA research grant project at the City of Buffalo, N.Y., to eval-
uate the pretreatment requirements for industries discharging to
the municipal treatment system. The second project is a research
grant to the Commonwealth of Pennsylvania to evaluate the
economic potential and feasibility of a centralized treatment
plant dedicated solely to industrial wastes.
Buffalo Study
The principal objectives of this study were to determine the
294
quantities of metals and organic matter contributed to the
Buffalo sewer system by industries and domestic sources and to
evaluate the impact of pretreatment regulations on the commu-
nity.
In order to obtain a material balance for the system, an
extensive survey was carried out to determine the amounts and
characteristics of wastes from various contributors. The major
sources of wastes were domestic, industrial, an interceptor
creek, and infiltration.
Estimation of Domestic Contribution
Domestic waste from an estimated 700,000 persons is received
by the Buffalo Sewer Authority from residential sources.
Estimates can be made for BOD and SS loadings from
literature, but the same cannot be said for metals loadings. To
obtain an estimate of these loadings, a sector of Buffalo's
residential community was examined. The results of this
sampling showed that only lead, mercury, and zinc were found
in measurable quantities above those normally found in Buffa-
lo's drinking water.
In order to estimate the domestic contribution of the loading
to treatment facilities, a water balance had to be developed.
Based on 1974 population figures, the resulting per capita
consumption was estimated to be 161 gpd which is reasonable
for Buffalo since residential users of water are largely untne-
tered.
Estimation of Scajaquada Creek Contribution
The Scajaquada Creek flows westward to the City of Buffalo.
As Buffalo developed, more and more sewage entered the creek
through overflows until finally it was enclosed at the city line
and made an interceptor for the sewer system. The Buffalo
Sewer Authority has a long term project underway to divorce
the stream from its sewer system; however, for planning
purposes it was included as a contributor.
Although organic analytical data is available on the stream's
quality where it enters the city's sewerage system, metals
concentrations had to be obtained. Flow data was avilable from
the United States Geological Survey gaging station at the city
line. The results of the Scajaquada Creek sampling indicated
that there were three materials present in quantities that should
cause concern: phosphorus, cyanide, and mercury. Approxi-
mately 56% of the mercury, 21% of the phosphorus, and 10% of
the cyanide loadings received at the Bird Island Plant originate
from the Scajaquada Creek. Industries upstream of the Scaja-
quada Creek's connection to the Buffalo Sewer Authority
system are probably the sources of these loadings.
Estimation of Infiltration and Inflow Contributions
For the Buffalo system, inflow may occur during dry weather
-------
EPA's Management Studies 295
whenever lake or river levels are higher than the overflow
chamber's inverts, since this allows these waters to flow into the
Buffalo Sewer Authority system. Based on the Authority's
average infiltration rate, 18.7 million gallons/day was estimated
for the infiltration and inflow contribution. To simplify the
balances, the quality of Lake Erie water was assumed to repre-
sent the quality of infiltration and inflow and was used to predict
their contributions.
Estimation of Industrial Contributions
The determination of the industrial contribution to the
Buffalo Sewer Authority system was accomplished by two
major tasks. These tasks involved the inventory and sampling of
the industries that discharge into the Buffalo Sewer Authority
system.
Identification of Contributing Industries
The first task was to compile a complete list of all types of
non-residential users of the Buffalo Sewer Authority system.
The industries ranged from restaurants and laundries to steel
mills and oil refineries, and included establishments in sewer
districts outside the city limits, but discharging to the
Authority's system, as well as the establishments within the city's
boundaries.
The list of contributors was established by using five primary
sources. These were:
1. Existing sewer authority files
2. City and State industrial directories
3. Water records
4. Tax records
5. Telephone yellow pages
From these sources, a list consisting of 343 commercial and
1,123 industrial establishments was obtained. By preliminarily
screening of this list for inconsequential contributing establish-
ments, it was possible to reduce the number of establishments
requiring further investigation to 631.
The next step was to evaluate the remaining industries in
order to estimate the characteristics of the waste discharged to
the sewer. This screening would allow a decision to be made as to
which industries would require sampling and analysis. To
obtain the data required to make this evaluation, an industrial
waste questionnaire was developed for circulation to the
selected industries. Water data were obtained from the various
water agencies for all the establishments. In addition, the
establishments were placed in Standard Industrial Classifica-
tions.
As completed questionnaires with production data were
received, a small number of companies surveyed were found to
be either out of business, moved out of the service area, or were
synonymical with other firms. This reduced the number of
establishments to 605. Table I shows the breakdown of indus-
trial users of the Buffalo Sewer Authority system.
Table I: Industrial Occurrence by Sic Divisions
Major Title
Occurrence
Division
A -
Agriculture, Forestry, and Fishing
2
Division
C -
Construction
4
Division
D -
Manufacturing
417
Division
E -
Transportation, Communications, Electric,
14
Gas, and Sanitary Services
Division
F -
Wholesale Trade
35
Division
G -
Retail Trade
31
Division
I -
Services
102
Total
605
From the quantity of water used, the number of people em-
ployed, and the production data, the industries were classified
as wet or dry. Thus, 185 were classified as dry. The wet industries
were then analyzed as to the type of raw materials used, the
quantity of water consumed, and whether the discharges
consisted of process water or cooling water. The industries'
wastewaters were then categorized into organic and inorganic.
Of the 420 industries classified as wet, it was determined that 309
should be investigated further. Shown in Table 2 is the distribu-
tion of the 420 industries by water usage.
From these 309 industries, 85 (representing a cross-section of
the significant types of industries found in the Buffalo service
area) were selected for sampling. These 85 industries were the
largest in their respective SIC categories.
Cross-section Sampling
The most important feature of any industrial waste survey is
the sampling and analysis program. The sampling and analysis
of wastes from the industries within a large municipal system
provide the data necessary to make sound engineering
judgements and decisions with respect to:
1. Locating and identifying the major industrial discharges.
2. Locating and identifying violators of the Sewer Regula-
tions.
3. Development of a system of protection for the municipal
treatment works to include the enforcement of Sewer
Regulations.
4. Recommending pretreatment systems which will satisfy
the Publicly Owned Treatment Work's requirements; and
5. The development of an equitable cost recovery system for
capital as well as operating costs.
Since the sampling program included 84% of the total flow
from Buffalo's industrial community, it was believed that the
results would provide a good background for estimating Buffalo
Sewer Authority's total industrial and commercial loadings.
The estimate was completed by using the sampled results in each
SIC category as an average loading for other industries in the
same category.
One of the problems which was encountered during the
sampling was in obtaining reasonably accurate flow data for
each sampling location of a particular industry. For an industry
having one discharge point, flows could be estimated from their
water meter(s) readings. However, this method could not
normally be used for industries having multiple discharge
points, unless it could be established that the water meter ser-
viced only that portion of the plant drained by the discharge
point in question. For these industries, flow data was obtained
by plant inspections whereby plant and Buffalo Sewer Author-
ity personnel estimated both the percentage of water used by
each process, and to which discharge line the process drained. In
this manner, an approximation of an industry's discharge could
be obtained.
Results of the Material Balances
Summarized in Table II are the results of the material
balances for four of the contributors to the Buffalo system.
These balances apply only to dry weather conditions. The
balances clearly indicate some important characteristics of the
Buffalo system which must be taken into account in future
planning. One of the most important areas identified by the
balances is that, with the exception of mercury, over 82% of each
of the metals loading is contributed by industry. This indicates
that an industrial waste control program will reduce these
loadings.
A second important area identified was compatible pollutant
loadings. The balance showed that 23% of the flow and 21% of
the phosphorus loadings were contributed by non-point
sources. This clearly pinpoints an area where the Authority
should direct its efforts to reduce the sizable operation and
maintenance costs of those non-point source contributions.
-------
296 EPA's Management Studies
Table II: Dry Weather Material Balances on the Buffalo
Sewerage System
Table III: Cost of Pretreatment Facilities
Infiltration Scajaquada
'arameter
Domestic
Industrial
and River Inflow
Creek
BOD
Kg/day
50,400
28,900
34
2,300
3
2,500
3
% of Total
60
:od
Kg/day
114,390
83,570
40
5,500
2.5
7,380
3.5
% of Total
54
rss
Kg/day
46,000
18,300
27
600
1
2,600
4
X of Total
68
'hosphorus
570
39
o
300
Kg/day
590
o
21
% of Total
40
Vrsenic
0.018
100
Kg/day
-
o
0
% of Total
0
Cyanide
1.04
3
26.5
87
3.03
Kg/day
% of Total
0
10
Cadmium
4.02
100
_
Kg/day
X of Total
0
0
0
Chromium
126.6
100
_
Kg/day
% of Total
0
0
0
Copper
Kg/day
2.96
128.0
97.3
0.7
0.5
0
% of Total
2.2
Lead
4.09
24.6
83.3
0.07
0.76
Kg/day
0.2
2.6
X of Total
13.9
¦lercury
0.15
5.0
1.67
Kg/day
1.18
o
55.7
X of Total
39.3
Uckel
_
Kg/day
-
63.9
100
0
0
% of Total
0
Sine
Kg/day
50.4
283.0
84.2
2.82
0.8
0
% of Total
15.0
Plow
70.8
u.o
75.7
Megaliters
/day 409
88. 5
13.7
11.8
X of Total
63.5
Industrial Pretreatment Requirements
A review of the Industrial Wastes Survey's results produced a
total of 30 industries that would require substantial pretreat-
ment of heavy metals before discharge to Buffalo's system. It is
expected that those industries, which have waste characteristics
only slightly in excess of the limits established by the regu-
lations, will make in-plant or product line changes to meet the
new discharge limits. Except for one industry, the method
proposed for pretreatment was single-stage lime precipitation. It
was anticipated that this remaining industry could meet the lim-
itations by increasing the efficiency of its present clarification
process.
Table III shows the breakdown for the industries affected by
SIC category. Approximately two million dollars will be used
for the construction of pretreatment facilities for plating
processes. In addition to 12 electroplating industries, Buffalo
has four industries in the Motor Vehicle Parts category whose
pretreatment requirements are a result of captive plating opera-
tions.
An alternative to having industries pretreat their own waste
would be to expand Buffalo Sewer Authority's proposed
treatment plant to provide the required treatment for incompat-
ible pollutants. To do this, Buffalo would have to remove the
same quantity of pollutants as would be achieved by the sum of
individual industry pretreatment facilities. Table IV, below,
shows the quantity of heavy metals that would have to be
removed, the projected plant influent, and the needed effluent
quality.
It was assumed that chemical precipitation could remove the
required quantities of heavy metals at the municipal plant. The
Buffalo Sewer Authority would most likely use a tertiary system
// of
SIC Category Industries
Total
Capital Cost
Total
Annual Cost
Converted Paper Prod.
Cylic Crudes
Pottery Products
Steel Wire
Copper Rolling
Hand and Edge Tools
Plating
Steel Springs
Refrigeration Equipment
Motor Vehicle Parts
Industrial Supplies
Industrial Laundries
Totals
1
1
1
1
1
1
12
1
1
4
3
3
30
0
0
84,580
310,000
657,140
292,790
1,010,280
50,850
80,450
1,064,500
147,280
267,480
$3,965,350
15,400
1,300
53,000
188,200
296,900
145,200
719,000
23,900
62,500
558,400
66,100
140,700
$2,270,600
Table IV: Requirements for Municipal Heavy Metal Treatment
[Parameter
Kg/day Removed
Influent mg/1
Effluent mg/1
.Cadmium
|chromium
Copper
Lead
Nickel
Zinc
2.5
100.0
104.0
19.3
40.5
205.0
0.008
0.254
0.198
0.044
0.096
0.514
0.004
0.104
0.041
0.015
0.035
0.207
to achieve these removals since the organic portion of Buffalo's
influent is already weak, a further reduction before biological
treatment would not be desired. Therefore, it was assumed that a
two-stage tertiary lime treatment system would be used.
The estimated costs for this type of treatment are shown in
Table 6.
The costs for a municipal treatment of heavy metals as shown
above, would be approximately three times the total cost for
industrial pretreatment. The large dilution of the industrial
waste received in Buffalo's system and resulting quantities of
chemicals required, make in uneconomical for Buffalo to
attempt treatment.
Table V: Tertiary Two-Stage Lime Treatment Costs for Heavy
Metals Removal at the Municipal Plant
Description
Costs
Capital Cost
$21,900,000
Annual Cost
2,334,900
Amortized Capital
Labor
341,200
Maintenance, Power and Heat
175,900
Chemicals
6,575,300
Savings in Phosphate Removal
2,520,100
Total Annual Cost
6,907,200
Assumptions
10% Interest
30 year amortization
400 mg/1 lima dosage
Residual Management
Pretreatment will substantially reduce the metal loadings
received at the Bird Island Treatment Plant. Once all of the
required pretreatment facilities are established, the Bird Island
Plant could have a reduction in the present loading ranging from
48.1% for cadmium to 79.0% for copper. This reduction in
-------
EPA's Management Studies 297
loading to the treatment plant would reduce the metal content in
the sludges. Shown inTable VI is a comparison of the estimated
sludge concentrations with and without industrial pretreatment.
As shown in Table VIII the industrial sludges resulting from
pretreatment metal concentrations will have high metals con-
centrations and proper disposal methods will have to be
employed.
Table VII: Examples of Industrial Sludge Characteristics
Kg/day Removed Cone @ 20% Solids
SIC Category
Dry
mg/1
Cyclic Crude
(2865)
Solids
9.8
20%
Zn
0.64
23,314.7
Steel Wire
(3315)
Solids
2383.5
20%
Cd
0.10
25.1
Cr
6.45
973.5
Cu
15.03
2269.2
Pb
0.50
75.4
Ni
0.41
61.7
2n
1.00
150.8
Fe
53.12
8021.0
Plating
(3471)
Solids
1184.9
20%
Cd
1.86
567.7
Cr
15.89
4846.0
Cu
10.99
3350.7
Fe
14.44
4402.9
Zn
7.17
2187.6
Ind. Laundry
(7218)
Solids
1162.7
20%
Cd
0.18
56.2
Cu
3.31
1026.1
Fe
69.05
21,380.3
Pb
11.58
3584.5
Hg
0.01
4.2
Zn
3.86
1194.8
Sludge disposal options in the Buffalo metropolitan area are
limited for industrial sludge. Reclaiming and recycling metals is
a possibility. However, when compared to the cost of pretreat-
ment required, it is not economically justifiable with the
methods available today. There are five disposal options which
could be used for the ultimate disposal of sludges. The following
is a brief discussion of each relative to its use in this area for the
disposal of sludges from chemical precipitation processes.
1. At the present time, landfill disposal of this type of sludge is
utilized in the Buffalo area. The relative cost of this disposal
method makes it the most economical option presently availa-
ble. However, increasing restrictions on the allowable metal
content may require creation of specialized landfills to handle
metal sludges.
2. The use of a scavenger is another option. In addition to
accepting sludges, the scavenger may also accept the liquid
wastes and then pretreat. While the ultimate sludge disposal
method used by the scavenger most often falls into one of the
other four options, it was included because of the potential for
reclaiming and recycling. For example, one scavenger operation
located in the Buffalo area is looking into recovering metals on a
large scale. It has already recovered copper from a highly
concentrated wastewater. Unless the sludges require additional
treatment or specialized storage in the landfill, it is more eco-
nomical to use the conventional landfill approach.
3. Ocean dumping is not a serious consideration for disposal
of the metal sludges since EPA will not approve same. Even so,
the transportation costs from Buffalo would be prohibitive.
Sludges are not allowed to be dumped offshore in Lake Erie.
4. The use of metal sludges for land reclamation in high
ground water areas or near lakes and streams would cause a
problem with water contamination. While land reclamation
may be used at selected sites, it probably will not be a major
method of disposal for this area.
5. Sludges, have been used both as a fertilizer and soil
conditioner. However, little benefit is seen from using the metal
sludges for this purpose.
Commonwealth of Pennsylvania Study
The objective of the Commonwealth of Pennsylvania study is
to determine the technologic and economic feasibility of
establishing a regional industrial waste treatment facility in a
significantly large area. This project is intended to accomplish
such an objective by a comprehensive analysis of the highly
industrialized lower 25-mile reach of the Monongahela River
near Pittsburgh, Allegheny County, Pennsylvania. A major
emphasis in this study is attaining treatment levels equal to or
better than Best Available Technology Economically Achieva-
ble (BATEA). This may well be feasible for a reigonal facility,
whereas individual plants may not be able to obtain this level of
treatment because of the lack of economies of scale, sufficient
financial or other resources, or simply sufficient recoverable
material to be worthwhile. The project is intended to provide the
following end products:
1. A proposed plan for facilities to treat, recover, and/or
dispose of industrial wastes to a level equivalent to
BATEA.
2. A method for financing these facilities at least cost to gov-
ernment and to industry.
3. Comparisons of efficiency and cost-effectiveness of the
regional system vis-a-vis the individual plant treatment
systems.
Inventory of Industrial Plants and Discharges
There are some 68 industrial plants along the lower fifty miles
of the Monongahela River which are potential dischargers to the
centralized industrial wastewater treatment facility. The present
discharges from these 68 plants average 1,522 MGD with
maximum reported discharges of 1,864 MGD. Elven of these
plants discharge an average of 1,506 MGD while the remaining
57 plants discharge an average of 16.4 MGD. All but 100 MGD
of the present average discharges originate in the lower 22.5
miles of the river.
Table VIII shows the present industrial plant discharges from
the 68 plants under consideration in terms of average and
maximum flows and loads of total suspended solids, oil, iron,
ammonia, and BOD. The differences between average and
maximum discharges point out rather clearly the major problem
with the use of industrial process water on a once-through basis
with terminal treatment facilities, i.e., the problem of slug
discharges due to equipment malfunction, accidental spills, etc.
All of the eleven large plants are in SIC group 3312, blast
furnaces and steel plants as shown in Table 10. This, of course,
reflects the fact that Pittsburgh is a major steel producing center.
Table VI: Pretreatment Effects on Buffalo Sewer Authority's
Sludge
Parameter
Without Pretreatment
mg/kg (dry)
With Pretreatment
mg/kg (dry
Copper
1570
330
Lead
1800
605
Nickel
315
115
Zinc
2275
364
Chromium
2540
1040
Cadmium
100
50
-------
298 EPA's Management Studies
Table VIII: Present Industrial Plant Discharges
5 7 Plant Total
11 Plant Total
68 Plant Total
Average Maximum Average Maximum
Average Maximum
If low
TSS,
(oil,
1 roii
[Nil,
'HOD,
. mRd
///day
///day
, "/daV
fl/day
ii / day
lb. 4
26. 7
31,270 46,759
/ 7 3
401
35.4
428
428
476
61.2
135
1,506
185,569
58,673
9,739
9,636
13,355
1,837
461, 254
697,967
15,370
21,450
13,355
1,522
216,839
59,446
10,140
9,671
13,783
1,864
508,013
699,395
15,846
21,511
14,490
Table IX: Industrial Plants by SIC Classification
11
i 2
is
.'0
28
2M
VI
\ \
*4
r>
40
4)
51
89
_ _ _ __ Industrial Classlficatlon
Anthracite Mining
Bituminous Coal and Lignite Mining
ftuildlng Construction - General Contractors
Food and Kindred Products
Chemicals and Allied Products
Petroleum Refining and Related industries
Stone, Clay, Glastf, and Concrete Products
Primary Metal Industries
Fabricated Moeal Products Except Ordinance,
Machinery and Transportation Equipment
Machinery, Except Electrical
Railroad Transportation
Local and Suburban Transit and Interurban
Passenger Tranaportation
Wholesale Trade
of Plants
Miscellaneous Services
1
4
1
2
3
3
4
19
4
3
5
1
2
1
2
Interceptor Sewer System
I he most obvious method of collecting and transporting the
indstrial effluents to be treated is an interceptor sewer which
would generally follow the course of the Monongahela River.
The terrain is exceedingly rough, consisting mainly of steep
hillsides and narrow valleys. The straight-line distance from
Allenport to the "Point" at Pittsburgh is 27 miles. Even though
i he river is 47 miles long, this course seems clearly preferable to
any contemplated system involving tunneling and construction
of lift stations to follow a straight-line course.
Regional Treatment Plant
The most logical basis upon which to design the treatment
plant was seen as the attainment of the BATE A discharge limit-
ations for each plant. Table X shows the total allowable BPTCA
and BATEA discharges from the 68 plants according to the
Proposed Effluent Guidelines.
Assuming that the reigonal treatment plant receives the
BPTCA discharges from each plant, the flow would be about
240 mgd. The interceptor sewer system is estimated to cost $3.0
million per mile, or $209 million in 1976 dollars. The proposed
treatment plant design incorporates alkaline chlorination,
Table X: BPTCA and BATEA Discbarges for 68 Plants
BPTCA Discharge
BATEA Discharfee,
Flow, mgd
TSS, #/day
0/C, #/day
|Ammonia, #/day
phenol, #/day
Cyanide, #/day
BOD,, #/day
Sulfide, tf/day
Fluoride, #/day
Manganese, #/day
Nitrate, #/day
Zinc, #/day
Lead, tf/day
Diss, Fe, #/day
(Tin, i/day
,Cr, #/day
ICr , #/day
241.18
27,427
19,946
27,330
511
2,001
27,163
1,613
8,380
1,391
21,821
893
38.5
225.5
834
501
3.5
32.16
3,926
2,134
760
168
23.4
782
24.1
1,425
77.2
1,010
71
3.9
57.9
37.
3.5
0.21
activated carbon adsoprtion, oil removal, metals precipitation,
and two-stage bio-oxidation. The reasoning behind such an
elaborate treatment scheme is two-fold; to attain a degree of
treatment equal to the most stringent effluent limitations which
could be imagined and to insure the ability to deal with slug
discharges, spills, etc.
The estimated cost of the treatment facility is $373 million.
This cost includes all auxiliary equipment, shops and adminis-
tration building, construction, and engineering. Land costs are
not included. Operating and maintenance costs are estimated to
be about 10% of capital costs annually for advanced waste
treatment plants. Operating and maintenance costs for the
regional wastewater treatment facility are thus estimated at $37
million annually for flows of 240 mgd.
In-Plant Treatment Alternatives
ln-plant treatment costs to meet steel industry BATEA
proposed guidelines are shown in Table XI as estimated in the
EPA Development Documents and in a National Science
Foundation study by Datagraphics, Inc.
Table XI: BATEA Treatment Costs (SMillion)
NSF ($1975) EPA ($1971) Probable ($1976)
jCoke Plants
Blast Furnaces
Sinter Plants
O.F. Shops
|Open Hearth Shops
Primary Mills
[Vacuum Degassing
Section Mills
jHot-strip Hills
jPlate Mills
Pipe Mills
iPickling Lines
[Cold Rolling Mills
Coating Lines
13.45
27.09
5.37
2.02
2.48
10.91
22.63
13.0
8.49
8.44
10.48
0
0
7.64
4.32
1.19
0.99
4.04
3.75
2.35
235.92
15.45
12.35
7.01
1.11
0
0.46
14.1 (1)
28.3 (1)
5.6 (1)
2.1 (1)
2.6 (1)
11.4 (1)
3.3 (2)
30.0 (3)
17.6 (3)
13.1 (3)
9.3 (3)
11.0 (1)
0
o-ft V)
149.0
(1) NSF
(2) EPA
(3) Average
Table XII: Cost Comparison-
Facility
-In-Plant Treatment Centralized
Centralized Treatment
150 mg.d 240 mad
ln-plant Treatment
For BATEA
(capital Costs, $million
Interceptor Sewers
Treatment Plant
BPTCA Credit
Total, net
(operating Costs, $million
BPTCA Credit
Treatment Plant
Total, net
111
307
(45)
373
(U)
31
20
209
373
(45)
537
(U)
37
26
164
49
The EPA data and the NSF data indicate operating costs of
30% of capital costs annually, or $44.7 million in 1976.
Assuming in-plant costs for the other-than-steel plants will, on
the average, be the same in proportion to flow, total capital costs
would be about $164 million; annual costs would be about $49
million.
Optimal Regional Treatment System
Although the proposed BPTCA Guideline Limitations would
result in a total effluent of 240 mgd, there is little doubt that
recirculation and reuse within the plant can result in a discharge
not exceeding 10% of the amount of the water used in the plant.
A flow to the treatment plant of 150 mgd should be easily
achievable.
In general, the system is envisioned as BPTCA treatment in-
plant. The treatment of strong spent pickle liquor is one excep-
-------
EPA's Management Studies 299
tion; there is no reason why such solutions cannot be fed at a
controlled rate and neutralized at the centralized treatment
plant in the proposed treatment scheme. This would provide
needed iron Hoc for oil removal and fine solids agglomeration
and provide an extra credit for the centralized system of about
$45 million in capital costs and $ 11 million per year in operating
and maintenance costs.
Cost comparison between in-plant treatment and the central-
ized facility are shown in Table XII.
From a mandatory point of view alone, the capital costs of the
centralized regional system would be about 2.3 times as great as
in-plant treatment to achieve BATEA. The operating costs,
however, would be only 40% of those for in-plant treatment.
-------
Dynamic Programming
Approach to Cost
Effective Industrial
Wastewater Treatment
Alternative Selection Kent E. Patterson
Roy F. Weston, Inc.
Richmond, Virginia
INTRODUCTION
Industry is faced with strict effluent limitations that require
large capital investment in wastewater treatment facilities. This
"non-productive" capital must compete with productive capital.
Also, the more stringent effluent limitations require labor and
energy-intensive treatment facilities with high operating budgets
as well.
Many processes are technically available to meet the
increased effluent restrictions. The engineer, faced with the task
of designing a wastewater treatment facility, therefore, must
select from the many alternatives the process which will
effectively meet the legislative effluent limitation restrictions in a
cost-effective manner. Also, management faced with large
capital expenditures for wastewater treatment are now very
interested in tradeoffs between in-plant process modifications
that reduce wastewater to be treated andend-of-pipetreatment.
Engineers can no longer make intuitive judgements with regard
to the most cost-effective solution. Therefore, an approach is
needed which will allow the engineer to systematically evaluate
all wastewater treatment alternatives available and select the
one(s) which meets the effluent restrictions at a mil'1113' cost. He
also needs the means to determine the sensitivity of the selected
alternative to the many variables which affect it. This is
particularly important to managers who plan the growth and
direction of a company. Answers must be given to the following
questions:
• What if the price of energy doubled?
• What is the sensitivity to labor problems?
• What are the alternatives?
• What is the sensitivity to further effluent limitations?
• What is its sensitivity to plant growth?
A first-generation dynamic computer programming model
(DYNAMO-1) has been developed and is operational; it will
evaluate over 3,000 separate wastewater treatment alternatives
and will select the optimum alternative, based on present worth,
for a given raw waste load in effluent limitations. The philo-
sophy used in developing DYNAMO-1 was to provide techni-
cally sound, cost-effective solutions to wastewater treatment
problems.
The model has been developed as a serial, multi-staged
decision system. A set of stages are joined together in a series so
that the output of one stage becomes the input of the next stage
(primary secondary to advanced waste treatment, etc.)
Serial, Multi-Stage Decision System
The serial, multi-stage system consists of a set of stages joined
together in a series so that the output of one stage becomes the
input to the next. Decision-making arises when there is more
than one feasible solution to a problem. Associated with each
solution is a number measuring its return. The decision-making,
or optimization, problem is to find the solution yielding the
maximum/minimum return.
A serial, multi-stage decision system is represented in Figure
1. Each stage is characterized by five factors:
1. An input state, X n, that provides all relevant information
about inputs to the stage.
2. An output state, X „ that provides all relevant informa-
tion about the outputs from the stage. Note that in the
multi-stage system, X n_, is the input state for the next
stage.
3. A decision variable, D, that controls the operation of the
stage.
4. A stage return, r, measures the effectiveness, or utility, of
the stage as a single-valued function of inputs, outputs,
and decisions. It is represented as:
r = rtXn,DXn.,)
5. A stage transformation, t, expresses, each component of
the output state as a function of the input state and
decisions:
Vl =
In contrast to other methematical programming techniques
(such as linear programming), a standard mathematical
formulation of the dynamic programming problem does not
exist. As previously discussed, dynamic programming is a
general strategy for optimization rather than a specific set of
rules. Consequently, the specific equations used must be
developed to fit each application.
Dynamic programming is essentially recursive optimization.
The recursive formulation used in DYNAMO-1 is as follows:
fn(n,s,x) = g[R(n,s,x), f*n.j(s')]
where:
n = the stage of the problem
s = the state of the system at stage n
x = the decisions (policy) being evaluated at stage n
R(n,s,x) = The immediate return associated with making
decision x at stage n when the state of the sys-
tem is s
s' = the state of the system at stage n-1 resulting from
decision x
f*n-i(s')= the return associated with the optimal se-
quence of decisions at stage n-1 when the
state is s'
In most cases a function of f*„_i(s') will be added to or
-------
Dynamic Programming Approach 301
Figure 1: Serial Multistage Decision System
multiplied by R(n,s,x). On the first stage (n=l), this term is not
included in the formulation.
At each stage, the results of the recursive formulation are
calculated for all feasible values of x, and the optimal decisions
are retained for subsequent use. The optimal value will be
denoted by f*„(s) and the optimal decision as x*n(s).
In contrast to the normal formulation of an optimization
problem, where the entire problem is solved as a total entity, a
formulation is developed that expresses the contribution of the
results of a policy at one stage of the problem to the total
objective function. This formulation is used to determine the
optimal policy for all possible states of the system for the first
stage of the problem.
Typically, the first stage in a dynamic programming formula-
tion refers to the last decision which must be made in a series of
sequential decisions (the "backwards" approach). The results of
this stage are then included in the next stage of the dynamic
programming formulation. This recursive procedure is applied
at each stage until the last stage is reached. The optimal policy
and value for the initial decision of the problem is thereby
determined as an application of Belman's Principle of Optimal-
ity. The optimal policy for each sequential decision can be found
by retracing the steps through the set of optimal policies found
for each state of the system at previous stages.
The method proceeds as follows:
1. Formulate the recursive relationship and all constraints.
Constraints are typically stated by specifying upper and
lower bounds of the state of the system and the decision
values.
2. Compute optimal values f* ,(s) and x* ,(s) for n-1, i.e., the
final decision point. The values of f* ,(s) will be retained for
use during the second stage computation. The values of
x* |(s) will be retained but will not be used until the final
calculations are completed.
3. The solution procedure then moves backward stage by
stage—each time finding the optimal policy for each state
of that stage—until the optimal value f*n (s) and decision
x*n(s) are found for the stage n-1, i.e., the first decision
point). Note that s now refers to the initial state of the
system since a backwards analysis was performed.
4. The optimal value of the other decisions is specified by the
values of x*n (s) for the previous n-1 stages according to the
state of the system at these stages.
A flow diagram illustrating this approach is presented in Figure
2. Since the objective in the model developed in this project was
to optimize waste treatment facility cost, the following recursive
Figure 2: Multistage Decision Process
relationship was developed:
fn(n,s,x) = C(s,x) + f* n_i(x)
In this relationship C(s,x) is the present-stage cost and f n-i(x)
is the optimal cost of the previous stage.
Wastewater Treatment Facility Optimization Algo-
rithm
Wastewater treatment facilities generally consist of unit
operations connected together in series. There is usually more
than one combination of unit operations that will technically
meet a set of effluent restrictions with a given raw waste load.
This automatically creates a problem of optimization for the
engineer: how, most cost effectively, to meet effluent re-
strictions with available treatment processes. This problem of
optimization fits the serial multi-stage decision model; in fact,
this is the problem addressed by DYNAMO-1. A design/cost
algorithm was developed to provide the "tools" required to
-------
302 Dynamic Programming Approach
quickly and efficiently select the best (i.e., most cost effective) al-
ternative from all available combinations of unit operations.
The program begins at the first stage of the problem (the last
step in the treatment process). This represents the final treat-
ment process before discharge. In this case, therefore, only one
effluent quality is produced, i.e., required by the effluent limit-
ation. The load to this stage is variable however. At each
incremental variation in load to a particular state (unit process),
a unit operation is designed to meet the effluent limit imposed
and is assigned a cost. Note that these increments in load to this
stage represent the variation in treatment possible ahead of this
stage. This increment/design/cost process is developed foreach
state (unit process) within the first stage. As soon as all states
have been given costs at each increment in load, a comparison
can be made to select the most cost effective alternative at each
load increment. The program then moves back to Stage 2. In this
case, since treatment processes may follow (Stage 1). both the
load and the effluent must be incremented. A state must be
designed and costed for incremental loads and effiuents. Note
that the effluent from Stage 2 represents the load to Stage I; but
the optimal cost to treat that load to meet the effluent re-
striction is already known. Therefore, at an incremental load, a
design and cost can be made for each state of Stage 2. T his cost
plus the optimal cost for Stage 1, at the increment in load
corresponding to the effluent from Stage 2, represents the
minimum cost to attain the effluent restrictions. This procedure
is repeated for each increment in load and effluent and for each
state (unit opeiation) in Stage 2. When this process is completed,
the optimal cost lor the first two stages at each increment in load
will be known. Again, these increments in loading represent
various degrees of treatment attainable by preceding unit
operations.
I his process proceeds backwards, stage by stage, until the
final stage is reached. At the last stage (representing raw waste
entering the treatment plant), the problem is simplified since the
choice to increment the load to the stage does not exist; the raw
waste load must be treated as received. Therefore, at the given
load (raw waste load), each state is designed and assigned costs
at varying treatment efficiencies. (This variation represents a
variation in load to the next to last stage.) For these variations in
load to the next to last stage, the optimum treatment scheme
(from stage n-1 to Stage 1) and cost is already known.
Therefore, the task at the last stage is merely to select the
increment in treatment efficiency and state (unit operation)
whose cost, when added to the optimal cost already known for
the preceding stage, is the lowest. Figure 3 illustrates the concept
of DYNAMO-I.
Early in the development of DYNAMO-1, it became apparent
that it would be desirable to look, not only at the most cost-
effective solution, but at several cost-effective solutions to the
Stage 5
Raw Waste Load
Stage 4
Primary Treatment
Stage 3
Secondary Treatment
Stage 2
Tertiary Treatment
Stage 1
Effluent Limit
Unit Op.
1
Unit Op.
1
Unit Op.
2
Unit Op.
2
Unit Op.
' ^ Unit Op.
Unit Op
N
1 N
N
Figure 3: Concept of DYNAMO-1
-------
Dynamic Programming Approach 303
problem. This essentially was no problem because the computer
model systematically looks at all feasible solutions. However, it
was soon realized that what really was desired was not the five
most-cost-effective solutions, but five most-cost-effective solu-
tions each of which would utilize a different unit process
configuration.The model selects the most-cost-effective alterna-
tive. In all likelihood, the second most-cost-effective solution
would not include a different combination of unit processes,
but, rather, would redistribute treatment efficiencies among the
same processes. For example, the most-cost-effective solution
might include primary clarification, followed by activated
sludge, followed by activated carbon, followed by filtration. The
second most-cost-effective solution would probably be found
consisting of these same unit processes in the same configura-
tion. The difference would be in the treatment efficiencies
obtained within each process. In other words, slightly more
BOD might be removed by the activated carbon system
(increasing its cost), with less BOD removed by the activated
carbon system (decreasing its cost). Therefore, the decision was
made to design the model to select the most-cost-effective alter-
native. Then the model eliminates from consideration the
selected unit process in Stage 1. The most-cost-effective solution
is then found.
The next cycle eliminates the process selected at Stage 2 of the
initial optimization. The optimal solution is found without this
unit process available for consideration. The model is designed
to cycle stage by stage until solutions are obtained omitting the
selected processes selected in the first optimization at that stage.
Model Components
Costs
Obviously any model optimization based on cost will be no
better than the cost data available to it. Therefore, significant
effort was placed on this portion of the model. Basically, two
problems must be addressed in development of the cost algo-
rithm:
1. Identification of all variable cost components.
2. Development of definitive relationships to reliably com-
pute these costs.
In the past, capital cost has been used as the primary
comparison/ selection parameter. Until recently, this was proba-
bly an adequate approach. The relative costs of labor, energy,
and other operating resources have historically been minimal
when compared to the cost of financing the construction of a
wastewater treatment facility. Recently, however, increased re-
source costs have made it imperative to consider annual O & M
costs in the cost-comparison process.
Replacement costs can be significant at facilities with long
planning periods or at facilities with high equipment replace-
ment frequency. These costs must be considered in the compari-
son of alternatives.
As important, and just as neglected as replacement cost, is the
value remaining in a facility at the end of its planning period.
These negative costs should be reflected as salvage value. All of
these cost factors can be important in the development and
selection of the most-cost-effective system.
Capital Cost
Capital cost has been, and will likely always be, the single-
most significant cost factor in any wastewater treatment facility
comparison. Wastewater treatment facilities are generally
capital-intensive projects. Capital for construction of waste
treatment facilities must compete with "production capital".
Since wastewater treatment facilities add little to the productiv-
ity of industry, this competition for funding is severe.
Considerable capital cost data are reported in the literature.
However, these data almost universally report capital cost as a
function of flow rate. This form of capital cost data is not
applicable to the dynamic programming approach developed
here, for two reasons:
• First, this format does not facilitate the application of these
curves to industrial waste, since they are generally devel-
oped for "typical" municipal wastes.
• Secondly, one of the key features of the dynamic program-
ming approach is the optimization of the total system
without concern about the optimal design of the individual
unit processes. .
The dynamic model requires the ability to consider variation
of the efficiency (and therefore size and cost) of individual unit
processes to optimize the total system. For these reasons, very
specific capital cost estimates are required for each unit process
considered by the model. Capital costs were developed as a
function of specific design parameters, such as basin volume,
surface loading rates, horsepower, etc.
Cost data of this type were developed for all unit processes
compared in DYNAMO-1. The costs were developed from
actual process design cost estimates. The costs represent
installed cost.
Operating and Maintenance
The increased cost of labor, energy, chemicals, etc., and the
increased technological complexity of wastewater treatment
systems have resulted in an increasing significance of operating
and maintenance costs. These costs must be included in the cost
comparison model. Included in operating and maintenance
costs computed in DYNAMO-1 are the following:
1. Labor costs.
2.Maintenance costs.
3.Energy costs.
4.Ultimate sludge disposal costs.
5.Chemical costs.
Labor Costs
The problem of computing labor costs for wastewater
treatment alternatives involves a breakdown of supervisory and
administrative, operating, and maintenance requirements by
individual unit operation. This requires a computation of the
annual man-hours required to properly operate and maintain
individual unit operations of incremental capacity. With this
information, appropriate staffing and wage rates are applied to
compute labor costs, This assumes: a 5-day work week; an
average of 29 days for holidays, vacations and sick leave; and 6-
xh hours of productive work per day. These data provided the
basis for development of the logic used in DYNAMO-1 for
computing labor requirements, and thus labor costs.
Maintenance Costs
Maintenance costs are a function of the type and function of
equipment. The equipment in wastewater treatment facilities
can be generally categorized as:
1.Structural equipment.
2.Mechanical equipment.
3.Process equipment.
Structural equipment primarily consists of buildings, roads,
basins, etc. These types of structural equipment usually have a
relatively low maintenance cost when compared to the other two
categories. Experience has demonstrated that annual mainte-
nance costs for structural equipment at wastewater treatment
facilities generally average approximately one percent of the
installed capital cost of this equipment.
On the other hand, mechanical equipment, consisting of
pumps, aerators, etc., has a relatively high maintenance cost in
comparison to the other categories. Experience has demon-
strated that an annual maintenance cost of approximately six
-------
304 Dynamic Programming Approach
percent of the installed capital cost is realistic for this type of
equipment.
Process equipment, such as clarifier mechanisms, multi-
media filters, etc., falls in mid-range with respect to maintenance
costs. Experience has demonstrated that an annual maintenance
cost of approximately three percent of the installed capital cost
applies to this type of equipment.
Energy Costs
One of the most dynamic and significant operating costs of
any wastewater treatment facility is its energy cost, which is rep-
resented by fuel and electrical consumption. Each mechanical
operation in a treatment facility, such as pumping,mixing,
aeration, etc., consumes electrical energy. Therefore, the hor-
sepower requirements for these mechanical operations are
computed and converted into electrical units (kwh). The "local"
energy unit cost is then applied to compute the annual electrical
energy cost. The same approach is used for the fuel-consuming
unit operations within an alternative. A Btu requirement is
computed, and local fuel costs are applied to compute the
annual fuel costs for alternatives. The electrical costs added to
the fuel costs represent the total annual energy cost for an alter-
native.
Ultimate Sludge Disposal Costs
Certainly ultimate sludge disposal represents a significant
logistics problem and cost factor in any wastewater treatment al-
ternative. DYNAMO-I maintains a "sludge audit" for each unit
process. A local unit cost for ultimate disposal of these sludges is
applied to compute the average annual ultimate sludge disposal
cost.
Chemical Costs
Chemical requirements are computed for each process. Local
costs of the various chemicals are applied to the annual
requirements to compute the cumulative annual chemical cost.
Replacements Costs
All equipment found within a wastewater treatment facility
has a finite service life. This service life represents the period of
time after which a particular equipment item must be replaced.
Mechanical equipment (such as pumps, aerators, etc.) tends to
have a low service life, e.g., less than 10 years, whereas structural
equipment (such as basins, roads, buildings, etc.) have a long
service life, e.g., in excess of 30 years. Appropriate service lives
were established for all equipment. The replacement cost for
unit operations is computed as follows:
Replacement Cost = Capital Cost X
Planning Period - Service Life
Service Life
This applies only to the equipment with a service life shorter
than the facility planning period.
Salvage Value
Equipment with remaining service life at the end of the
planning period has a "salvage value". This value represents a
negative cost, or credit. Salvage value is computed as follows'.
Salvage Value = Capital Cost X
Service Life - Planning Period
Service Life
This is valid only for equipment with a remaining service life
at the end of the planning period.
Present Worth
Ideally, all of the foregoing individual costs should be
combined into a single value for optimization in the dynamic
model. Also, the cost of financing (interest) should be included
in the comparison. The present worth analysis provides a
method of accomplishing this comparison.
Present worth is defined as "the sum of money required
which, if invested at a specified rate of interest over the life of the
project, would provide exactly the funds required for the
expenditures of the project throughout its life".
Table 1 illustrates the method used to apply the present worth
analyses in DYNAMO-1.
Process Design
The function of the design algorithm is to provide a systematic
design procedure for individual unit processes to enable applica-
tion of the cost algorithm in a dynamic programming format.
As discussed earlier, wastewater treatment facilities are
essentially multi-stage systems. Each stage represents a level of
treatment for the pollutants being considered. Within each stage
(level of treatment) are often several states (unit processes) that
may effectively remove specific pollutants.
An important feature of the model is the existence of a "no
treatment" state within each stage.
The major function of the design algorithm is to provide
designs for costing. Each unit process is designed according to
the wastewater characteristics, effluent requirements, and
treatability characteristics defined for each specific problem. All
of the design routines are modular to facilitate maintenance,
modification, replacement, or addition of new processes.
Input/Output
One of the major problems encountered with any modeling
effort is the coordination of input/output (i/o). Adequate data
must be provided to define the problem as specifically as
possible. In return, the user must be supplied with a complete
summary of the model's activities.
Input Requirements
The major task of the user of DYNAMO-I is to provide
adequate input data to allow the optimization process to
proceed. Three categories of input are required: wastewater
characterization/effluent limit, cost information, and unit
process design parameters.
Wastewater Characterization/ Effluent Limitations
Data are required which define both the raw waste load and
the effluent limitation. Table 2 provices an example of the actual
wastewater characterization /effluent restriction data required
by DYNAMO-1.
DYNAMO-1 will operate without actual input from the user.
The model will automatically select default parameters and lim-
itations in the absence of actual input. The only exception is that
the wastewater flow rate must be provided.
Cost Information
Cost is the basis for optimization by DYNAMO-1. Current,
high-quality cost data are required. Capital cost curves are
internal; however, the current ENR Construction Cost Index is
required to update these curves. Current local land prices are
required.
Operating and maintenance costs represent volatile portions
of the cost routines. Therefore, current data must be provided to
allow DYNAMO-1 to meaningfully compare alternatives on a
cost basis. The following O & M cost data are required by
DYNAMO-1:
1. Labor cost. 3-Ultimate sludge disposal cost.
2.Energy Costs. 4.Chemical costs.
-------
Dynamic Programming Approach 305
Table I: Present Worth Analysis
Cost 1tem
Factor
Present Worth
1. Capital Cost
nl
2. 0 £ M Cost *
uspwf
1
i
n2
3. Replacement Cost x
sppwf
"l
Salvage x
Sppwf
I
(...)
TOTAL PRESENT WORTH
Where:
planning period
In years
°2
service 11fe,
in years
i
rate of Interest, percent
sppwf
sing\e-payment
present worth
factor,
(i ~ d"
Uipwf
unlform-series
present worth
factor,
(1 + 1)" * 1
K1 + Dn
Replacement Cost
Cap i ta1 Coat
x
"2 ' "2
(n, =- Bj)
n2
Salvage Value
Capital Cost
*
"2 " "l
(n^ ^ n^)
"2
Tabic II
TCS1 OF OYNAftO " * AUGUST
•• OPTIONS selected ••
•• KnCml Input •*
HOtLOTt'JT SfLECIEO-UMS
interest r»te T.40PC
PRINT OMIT PROCESS INPUT VEKJFICATION-TfS
INFLATION kATE H.SOPC
print control fo* detailed calculations, i
CNR INUii 2200.
PRINT 1 LrAST COSTLT SOLUTIONIS!
Planning period so tca*s
EFFLUCNI Cn«JCrNl«ATlON kESulXfO
s.oo «g/l
»• wASTt ImFLUCIT CHARACTERISTICS
»•
•• various o»m costs *•
-orscRrPTiON- -value*
units-
•DESCRIPTION- -VALUc-
-UNITS-
FLOW 10.00
n6D
lUPENVtSOR 20.00
»/hr
boos aso.oo
N6/L
OPERATOR 10.00
*/HR
TSS 250*00
H«/L
clerical a.oo
S/hR
con tso.o#
NG/L
las personnel is.to
*/mr
NHS 30.00
NG/L
total P 10.00
NG/L
electric m,
s/rm.m
alkalinity 500.00
NG/L
FOELtOILl (.SO
l/Ul
«A*I«u" ptt T.40
*/AC*C
HlhinuP PH 7.40
stuofct disposal s.oo
•/ION
SUH*CP TCNpcMATUHt 20.00
K< C
blNTfR TENncRATUHc 20.00
DC* C
• • rHtftiCAi cgsis •«
-* :»CH«'Tl«'J.
mm-
-tlNlli-
ALU»TNON S ULFATE
20.SO
• /TON
C*LC1U». «*ijr
s«.»o
A/TON
CALflu* Hoil1E
«.oo
• /TON
tshpic cMftdiDr
(/TON
ialciu" «tf>ocL(wirr
21.00
•/TON
IHLOR INI
II.M
•/TO*
-------
306 Dynamic Programming Approach
Table 111
^EST of UYMAMO - 1 AUGUST Jit I97f.
ARE * UNIT PROCESS 11 - ACT-SLUb
** input verification **
INSCRIPTION
removal ratl coefficient
/
-------
Dynamic Programming Approach 307
Table IV
TEST OF
APO - I At'&UM 17. 1976 TFB/RAR/AKO/mH
STAfit I
UNIT HPncESS 1 - PRI1-CLF OESr
OtiIGN UASIS
FLOW. ¦(.!'. =
10.00
TSS. Ili/L =
260.00
HODS, "G/L •
22.¦so
lab overflow Sate, gpo/sq-ft =
1093.16
lMlCKlk.LH LOAJIHO. LbS/Su-M/DAY =
?o. nn
VAC-FILTER L0AUTN6. LUS/HK/40-FT a
7.00
0EWATE9EO SLUQur. PCT SOLlfJi 1
28.on
planning periou. yrs =
AO
CLAHlFIER SERVICE Lift. YKS I
so.no
THICKINLK SERVICC LIFE. =
so. 00
VAC-FILIE* SE«V|Cf LIFf, YMS r
25.00
SLUDGE PU"P SCHV1CE LIFE. YKS z
io.no
OPERATING PARAMETERS
NUHUeR OF CLARIFIERS s
1.00
surface area, so-ft (each) =
15755.
DESIGN OVERFLOW rate. bPO/SW-FT s
766.1«
** INLET OUTLET LOSS. PERCENT =
20.71
CFFLUCNT TSS. h&/L =
77.32
EFFLUENT TSS. LaS/UAY 1 OKY 1 =
6««9.29
EFFLUENT ROUS. <«G/L *
19.00
EFFLUENT BOOS, lbs/oat S
1250.99
SLUDGE PUPP CAPACITY, GP* =
ss.os
thickener surface area, so.ft a
720.01
VAC filter surface area, so-ft =
85.71
SLUDGE pupp capacity, hp =
0.09
OEwAtERED sluogf. CU-YO/DAy z
J*.19
POLLUTANT
RAb wASTE(p6/l» STAGE INFLUENT 1 ne/LI STAGE EFFLUENT(PG/LI EFFlUCNT lI"IT
1 a BOOS
240.00 22.50 19.00
5.00
8 • TSS
290.00 230.00 77.»
S « NHS
30.00 SO.00 90.00
« * PHOS
10.00 10.00 10.00
S * COO
790.00 7SO.OO 790.00
-------
308 Dynamic Programming Approach
Table V
TEST Of DYnAHO - I AUGUST IT. 197'
STACE I UNIT PROCESS 1 - PKIH-CtF
TfB/RAR/AKO/kP
DCSC
COST Sllh«A«* COi>»
0.
0.
217»u.
5110.
a.
0.n2b8
0.0268
0.1639
0.4851
O.OUOO
0.
0.
3573.
2479.
a.
SUH-TuTAi.
26"»C.l.
6052.
SALVAGE CUSTS
CLA»!FItH(SI
TMXCKFhFR(SI
VACUUM FILTER (S.I
SLUi'Sr pyiH(S>
LAN', COST
-2iei2u.
•21371 •
0.
0.
-193H.
0.1142
0.11^2
0.1142
0.1142
0*1142
-24-M4.
-2441.
0.
0.
-4*9.
sur-toial
-24J433.
-27805.
total pklsfnt ^pctm
2108126.
Table VI
TEST OF imiA*0 - I AU.iuST 31. 197* TFB/RAR/AkD/KP
STAGE 1
STAGE 9
stage S
stage 1
PMM-CLF
ALT-iLlir,
break-pt
POL-POHjn
SliC—LIMC
aer-lagm
lON-EXCH
ACT-CRD11
two-lime
ROT A-DIn
NO TREAT
filtratn
Mi trfat
NO TREAT
lano-apl
ter-like
NO treat
** SYSTEw CONFIGURATION **
STAfiF 5 STaGT. 6 STaGE t STAGE fl STftGE 9 STAGE 10
-------
Dynamic Programming Approach 309
Table VII
test cf
OYHaNO - X august 31, 197o
TFB/FttK/AKO/KP
PlUHftRY POLLUTANT H005
»• SYSTEM configuration
SUMMARY «»
ahqtTIObAL lfast
COSTLY SOLDTIOM
CUMHULATIWE
POLLUTANT
SUMMARY
INFLUlNT
r FFt 'JrNT
ST/.G[
1'RE.SfNT WORTH
PR^SrNT WORTH
--
UlITT
CONCENTRATION
COUCENTRaTTIN
pfrcent
COST
COST
-IN-
-OUT-
5TASE PROcrSS
C.li/L)
(l*C,/L>
removed
(DOLLARS)
(DOLLARS)
(HG/L)
(MG/L)
1 phi«-clf
250.00
lT-i.On
30.0(1
787715,
787715.
BODS
250.00
175.00
TSS
250.00
102.89
NH3
30.00
30.00
T-P
10.00
10.00
COD
750.00
750.00
;¦ ROTA-nio
175.00
ln.oo
9H.28
1585625.
237331U.
B0D5
175.00
10.00
TSS
102.8S
36.00
NH3
30.00
1.50
T-P
10.00
10.00
COO
750.00
750.00
3 NO TREAT
lO.OO
io.oo
0.00
0.
23733H1.
BODS
10.00
10.00
TSS
36.00
36.00
NH3
1.50
1.50
T-P
10.00
10.00
COO
750.00
750.00
i no treat
10.00
10.UO
0.00
0.
237S3H1.
BOQ5
10.00
10.00
TSS
36.00
36.00
NH3
1.S0
1.50
T-P
10.00
10.00
COO
750.00
750.00
Table VIII
TEST OF DYNAMO - 1 AUGUST 31
, 1976 TF6/RAR/AKD/KP TABLE 8
STAGE 1 UNIT PHOcrSS 1 -
prim-clf orsr
DESIGN BASIS
OPERATING PARAMfTEHS
FLOW, PIGD
= 1.00
TSS, MP/L
= 250.00
NUMBER OF CLARIFItRS
s
1.00
nCD5, MG/L
= 250.00
SURFACE AREA, SQ-FT (EACH)
s
987.95
LAb OVCKKLOW HATE
. GPO/SQ-FT
= 2231.99
DESIGN OVERFLOW RATE, GPO/S1-FT
s
1135.99
THICKENER LOADING
. LHS/SO-FT/oAY
= 20.00
~» INLET OUTLET LOSS, PERCENT
3
41.87
VAC-FILTEP LOAOTNG, LBS/HR/SO.FJ
= 7.00
EFFLUENT TSS, Mfi/L
=
102.89
nEWATERED SLUDGF,
PCT SiOLInS
= 25.00
EFFLUENT TSS, LPS/DAY ( DRV )
ss
858.18
PLANiJING Pr«IPt'..
YRS
= 30
EFFLUENT BOOS, KG/L
s
175,00
CLARlFTtK SLRWJCF
life, yf EFFLUENT
LlHlTt!W/L>
1 = BOOS
250.00
250.00
175.00 10
.00
2 = TSS
250.00
250.00
102.89
S s NHS
30.00
3o.on
30.00
if s PHOS
10.00
10.00
10.00
s = con
750.00
750.00
750.00
-------
310 Dynamic Programming Approach
Table IX
TEST OF UYij/VIO - 1 AUOUsl 51. l')7f.
STA'-f- ;> 'JUT PPnrESS 30 - RGT/1-nio
rri'./RAlt/AKIVKP
I'tsr
orsion basi?
FLOW, noc
INFLUENT Rfli), f,r./L
FFFLUE.i.T T.S.C, .-11113 PEflOVAl . PC
=
95.00
UISESTOh volume, GAL
=
39^«2.lft
0? RCOUIHT') FOR PIGFSTOR' LbS
r
230.<49
DIAMfTjrK OP T'-lJeKLiiEF'• FT
=
10,57
THI CKEMED SLUfjuF rURPIMS HAll, GPM
s
1.B2
M-F' FOR LlTGETSTd ?. rip
-
3.03
H-P FOR Bin nisr. HP
a
3f>.69
recycle f'i>»ps. m»
=
0.00
THICKcMD SLUDGr FuMP HP
s
o.m
VACUUM FILTER AREA. SO-FT
s
2.P8
LAND RFOUIPEOt Al^ES
=
0.72
PjLLUTAN r
a = H005
? = TSS
4 = f-JH*.
14 - PHOS
5 = con
-I. ^^rtFFrUENT^G/[r"FFFL^jE"ir[^n^G/u"
ris >*£ -> A . 4 7K A A
250.00
?«;o.oo
<0.00
1C.00
7">0.00
17*.00
10?.89
30.0 0
10.00
750,00
10.00
36.00
1.50
111.00
750.00
10.00
-------
Dynamic Programming Approach 311
Table X
TFf.T OF DrflAMO - I AUGUST 31, 1976
StAfit 1 UNIT PROCESS 1 - PRIM-CIF
Tn
nUCKrUfl-'
LAliCK LOST
tfAI fiTrhAr:CF. r CISTS
FNEP6Y COSTS
SLUOGF disposal costs
ChE^UAL COSTS
sun total.
RrPLACrMFUT costs
CLARTFIER(S)
THIC«ri,FW
VACUUM FiLTCR(S)
SLUnGf PIJI"P(S)
LAN:) COST
SUH-10TAL
SALVAGE COSTS
CLANIFIEHISI
THIrKFNri'' (S)
v/acuuc filteks>
SLunsr HufPiS)
LAND COST
sun-TOTAL
COST
117966.
21630,
77632.
122?.
1 nii.
252186.
30<»0ft.
9909.
15.
5317.
0.
'~5660 •
0,
0.
15526.
2115.
0.
17971.
-59106.
-9952.
0.
0.
-1031.
-70073.
p-w factor
1. n l> o o
l .oooi)
l.r.ooo
1 • 0 JU(J
1. PUPO
n.fiua
11.104
11.«103
0.0-268
0.026o
0.163*
0.1«51
0.0000
0.1112
(1.1112
0.1112
0.1112
0.1112
present WOKTH
117966.
21630.
77632.
1222.
1031.
252136.
359129.
117031.
512.
62796,
0.
539500.
0.
0.
2516.
1186.
0.
1732.
-6760.
-1125•
0.
0.
-116.
-8003.
TOTAL PRESFNT WORTH
787715.
the model. The first application is to the existing facilities. In this
case, the model does not select alternative configurations for the
existing facilities, but develops a cost estimate based on the age
of the facilities. The second application results in full optimiza-
tion of the additional facilities required to meet the effluent re-
strictions.
DYNAMO-1 is modular; this facilitates maintenance on the
model as well as additions to it. Should additional unit processes
be desired, the design subroutines are merely added to the
package. Very limited interfacing is required. The cost
subroutine can be replaced or modified easily.
A key feature of DYNAMO-1 is the ability to perform
sensitivity analysis on various cost compents. For example, the
impact of increased labor, energy, land, etc. costs can be quickly
and easily evaluated by modifying the various cost items and by
monitoring the changes in the recommended alternative(s). This
provides a valuable insight to the user: he can easily determine
the significance of difficult-to-predict cost items to his recom-
mended alternative.
DYNAMO-1 is totally unbiased by all factors other than cost.
Political preferences, personal preferences, etc. are not reflected
unless a cost can be associated with them.
ACKNOWLEDGEMENTS
The author would like to express his appreciation to the many
people involved in converting his ideas into a working model.
First, ROY F. WESTON should be commended for establish-
ing a corporate R&D Committee to select and fund R&D
Projects proposed by Weston staff.
The author wishes to thank members of the R & D staff for
their valuable advice and guidance throughout this project.
-------
312 Dynamic Programming Approach
Table XI
TEST OF CjYsMAMO - I AUGUST
¦51, 1976 TFH/RAR/AKlI/KP
TARI P 11
STAGE 2 ufJIT PROCESS 10
- ROTA-HID PESr
lnOLC I|
COST SUMMARY (QOLI.ARS)
COST
P-U FACTOR
PRESENT WORTH
capital cost
biu fJISCPFACTuR INC TA-MfS
374?61.
l.nCOU
374361.
AER«ToHS
0.
1. 3 il 0 fj
0 .
SECOPJMARy CLAKIFTEHS
19474 G •
l.nuoo
194746.
HrCYClE PUMPS
/ 0.
1. n 0 c o
0 .
THirKrNCKs
26431.
1. nil oo
26431.
TMIrKrhlCO SLllOPE. PUMPS
fl.
1 . CiCUO
6,
AEKnflJC illGESTOR
43051.
l.nooo
43051.
OISrSTOH AERATORS
12he.
l. ,i c o a
1256.
VACUUh FILTCRi
67JS2.
1 . 0 J 0 u
67152.
LAN! COSTS
2690,
l. uuoo
2690.
SU'WoTAl
711723.
711723.
0 ~ n COSTS (ANNUAL 1
LABOR COST
¦~9010.
11.6103
57«626.
maintenance costs
14974,
11.6103
176659,
ENERGY COSTS
10367.
11.6103
122664.
SLUuGt DISPOSAL COSTS
1902.
11.6103
22472.
CHEMICAL COSTS
0.
11.1.10 3
0.
sun TOTAL
76275.
900642.
Replacement costs
bio qiscreactor TMC Tanks
0.
n.0266
0.
AERATORS
0.
0.3379
0.
SECONDARY clarifiers
C.
0,0260
0.
RECYCLE PUMPS
O.
0.4651
0.
THInKf NCRS
0.
0.0266
0.
thickfned sluuge PUMPS
16.
0.4651
S.
AERUfltC DIGESTOR
0.
0.0266
0.
DIGESTOR AERATORS
1256.
0.3379
423.
VACUUM FILTERS
13430.
0.1639
2202.
LANO COSTS
0.
0.0000
0.
SUR-TOTAL
mos.
2635.
salvage ccsrs
UlO HSCREACTuR T SIC TawKS
-149752.
0.U42
-17105.
AERf TnKS
0.
0.1112
0.
secodhary clariftfrs
-77699.
o.ll'.e
-6697.
fitCYClE PUMPS
0.
o. i m 2
0.
Ti)Ir«rNERS
-11372.
n. i
-1299.
THICKrMFD SLUoGf pumps
0.
0.1142
0.
AEKoniC Di&rSTOR
-17220.
0.114*
-1966.
r.IKFSTOK AERATORS
u.
L.1142
0.
VACUUM FILTCRS
0.
0.1142
0.
LAnlH COSTS
-2690.
0.114c
-307.
SUII-TuTAL
-256935.
-29576.
TOTAL PHCSpiT wor-:TH
1585625.
A special thanksgoestoT. F. Bergen, Dr. A. K. Deb, and R. Department, for their tireless efforts in making DYNAMO I *
A. Radcliffe, all of the Weston Computer Sciences and Systems reality a
-------
Financial Planning
of Industrial Pollution
Control Facilities
Thomas L. Davis
and
A. F. Miorin
Gannett Fleming Corddry and
Carpenter, Inc.
INTRODUCTION
During the 1970's we have seen a proliferation of federal leg-
islation designed to protect the air, water, and land resources of
the United States. This legislation has not merely supplemented
already existing environmental laws of our fifty states, but in
many cases, actually resulted in increased numbers of further
regulations and programs on the state and local levels. Now,
recent federal legislation is being directed toward protecting the
health of our human resources as well. As we move into the
1980's, additional laws, regulations, and programs can be
expected, further restricting the degree to which man can pollute
his own environment.
Although necessary and well intentioned, these laws have
had, and will continue to have, a major financial impact on
industry. The installation of pollution control facilities has
become mandatory for many industries resulting in significant
capital expenditures where means for recovering these monies
may be limited or nonexistent. Depending on the magnitude of
these expenditures, serious cash flow problems could develop,
affecting ultimately the profit-making position of the company.
As a result, corporate environmental decision-making has
become both frequent and important.
It is the purpose of this paper to set forth and discuss the
major elements involved in the financial planning of industrial
pollution control facilities. The material presented has been
selected to aid management in the two areas of decision-making
common to the consideration of all proposed pollution control
projects: (1) the financing decision, i.e., where should the capital
funds for the proposed project be obtained, and (2) the capital
expenditure decision, i.e., which of several technically feasible
alternatives is most acceptable in terms of the financial policies
and goals of the company. Current federal tax laws, alternative
tax schemes and state tax incentive programs will be identified
and their effects on cash flow discussed. Commonly available
sources of project financing will be identified, discussed, and
evaluated. A method for analyzing proposed project capital
expenditures will be presented incorporating several common
management objectives when considering a proposed
investment. Finally, an application of the financial planning
process will be illustrated in the selection of the most cost-
effective treatment and control arrangement for an industry
generating both sanitary and process wastewaters.
Elements of Financial Planning
As illustrated in Figure 1, seven major steps comprise the
financial planning process:
Step 1: Identify and evaluate all technically feasible engineer-
ing alternatives;
Step 2: Develop capital and annual costs for each alternative;
Step 3: Identify management's financial objectives;
Step 4: Identify all permissible tax strategies and evaluate the
effect of each strategy on corporate cash flow;
Step 5: Identify all available sources of project financing and
evaluate the effect of each financing strategy on corporate cash
flow;
Step 6: Utilizing the capital and annual costs associated with
each alternative, analyze all possible combinations of project
financing and tax strategies in terms of management's financial
objective; and
Step 7: Select the most cost-effective engineering alternative,
tax strategy, and source of financing.
Figure 1: Steps in Financial Planning
The importance of each of these steps in the overall planning
process is set forth in the sections which follow below.
Step 1: Identfication and Evaluation of Engineering
Alternatives
313
-------
314 Financial Planning
The initial step in the planning process is the identification of
engineering alternatives. The number and nature of the alterna-
tives to be considered will of course depend on the magnitude
and type of project being proposed. However, each alternative
so identified should be evaluated in terms of satisfying the
following criteria:
1. The alternative will achieve the technical objective of the
project;
2. The alternative is independent of all other identified alter-
natives; and
.3. Physical units and consequences associated with the alter-
native can be expressed in money units.
Alternatives satisfying these criteria should then be developed
so that future cash flows for each can be accurately estimated.
Step 2: Development of Capital and Annual Costs for
Each A Iternative
For each alternative selected in Step 1, comprehensive
estimates of capital and annual costs, and potential revenues
should be prepared. Estimates of times when these cash flows
are expected to occur should also be determined. Once future
cash flow magnitudes and times have been established, the
financial analysis of each alternative can then be performed.
Step 3: Identification of Management's Financial Objec-
tive
One of three differing financial objectives are typically sought
by management in considering any proposed project, these
being:
1. Minimum long-term profit impairment;
2. Minimum short-term profit impairment; and
3. Minimum peak cash outflows.
The first of these objectives, minimum long-term profit
impairment, is typical of large firms with sufficient financial re-
sources and cash flow stability. Such firms generally wish to
maximum long-term profits. For this objective, alternatives
would be compared on the basis of balanced cash inflows and
outflows over the lifg of the project.
The second of these objectives, minimum short-term profit
impairment, is typical of those firms that need to demonstrate a
strong short-term net income to stockholders or creditors. For
this objective, alternatives would be compared on the basis of
minimizing tax liabilities during the first several years of the
project.
The third of these objectives, minimum peak cash outflows, is
typical of those firms with year-to-year cash flow problems. For
this objective, alternatives would be compared on the basis of
minimum peak cash outflow in any one year.
No specific financial technique is required for analyzing al-
ternatives in terms of the last two objectives. Comparisons
between alternatives are based entirely on the magnitude of
annual cash inflows and outflows. Use of these two objectives in
the selection of a cost-effective alternative will be illustrated in
the sample problem to be presented later.
The financial technique most commonly employed for
minimizing long-term profit impairment is the present worth
method. Present worth means simply present value. In this
method all future cash flows associated with a particular alter-
native can be expressed in terms of present day dollar values.
When applied to the cash flow pattern associated with each al-
ternative, the present worth method enables alternatives to be
immediately compared on the basis of their equivalent present
day value.
To illustrate the present worth method, consider the following
simplified example. One dollar saved today has a present worth
equal to one, i.e.:
PW = 1 (1)
The dollar saved today, however, has the potential of yielding a
return r if used by the company for profit making operations.
Therefore, if this dollar was saved one year from now, its present
worth would be less than one, i.e.:
PW = l/(l+r)
(2)
Similarly, if this dollar was saved x years from now, its present
worth would equal:
PW = l/(l+c)x (3)
The calculation of the present worth of the dollar, in our ex-
ample above, invested at various times in the future is called
discounting. The return rate r used in present worth calculations
is generally referred to as the discount rate. This rate should be
greater than or equal to the company's after tax rate of return
used in profit making investments. The parenthetic expression,
1 + r, is called the discount factor. When the present worth of a
net cash flow, NCF, in some future year x is calculated using the
discount factor, the resulting cash flow is called the discounted
cash flow, DCF:
DCFX = NCFx/(l+r)x
(4)
The total of all discounted cash flows over the duration of the
cash flow period, n, is the net present worth, NPW, of the cash
flow pattern:
NPW = x=f 2 DCFX = X=Y 2 NCFx/(l+r)x (S)
In the following sections, this analysis will be utilized in evalu-
ating cash flow effects resulting from various tax and financing
strategies, and in the expenditures of capital funds on a
proposed project.
Step 4: Identification and Evaluation of Permissible Tax
Strategies
T wo types of federal tax benefits are available to management
for capital expenditures in plant equipment. The first of these,
depreciation, allows a portion of the capital cost of the
equipment to be deducted yearly from a company's taxable
income. The second of these, the investment tax credit, enables
management to lower its tax liability in the first year of
equipment operation by a percentage of its capital cost.
The effect of these tax benefits on cash flow is best described
by the following equations:
TXPx = TXR (REVX - OPEXPx
TXDEPx)
(6)
Where: TXPx = Total tax payment in year x (dollars)
TXR = Corporate tax rate (%/100)
REVX = Total revenue in year x (dollars)
OPEXP = Total operating expenses in year x (dollars)
TXDEPx = Total tax depreciation in year x (dollars)
Forx = 1:
Where:
TXP^ TXP, -(ITC • INV)
(7)
TXPi1 = Total tax payment in year 1 (dollars)
TXPj = Total tax payment in year 1 as com-
puted by equation (6) (dollars)
ITC = First year investment tax credit (%/100)
INV = Investment or capital cost of the equip-
ment (dollars)
-------
Financial Planning 315
As shown in equation (6), the total tax paid by a firm in any
one year x is equal to its tax rate times the algebraic sum of its
total revenues, operating expenses, and tax depreciation in that
year. Current tax rates for domestic firms are 20% for taxable
income up to $25,000, 22% for the next $25,000,and 48%on tall
taxable income over $50,000. The effect of the investment tax
credit, which may be elected in the first year plant equipment is
put into operation, is shown in equation (7).
The significance of the tax depreciation amount is that it is
accounted for as a noncash expense. The greater the tax
depreciation amount, the lower the tax paid. Three methods
approved by the Internal Revenue Service for computing tax
depreciation amounts for plant equipment, including pollution
control equipment, are: (1) straight line, (2) sum of the year's
digits, and (3) double declining rate.
Straight Line Method:
DCX = (P-L)/n (8)
BVX = P-X • (DCX) (9)
Sum of the Year's Digits Method:
_ 2 [n-X+1 ] (P-L)
n2 + n (10)
BVx = P"i=lX 2 DCi (11)
Double Declining Rate Method:
f = 2.0/n (12)
BVX = P(l-f)x (13)
DCX = BVx.!-BVx (14)
Where: P = First cost of the equipment (dollars)
L = Salvage value of the equipment (dollars)
n = Economic Life of the equipment (years)
DCX = Depreciation charge in year x (dollars)
BVX = Book value of the equipment in year x
(dollars)
To compare the difference in annual and total tax payment
computed by these three methods, the present worth method de-
scribed earlier will be used. The net cash inflow in any year x
resulting from the tax depreciation amount deducted in that
year may be expressed as:
NCFX = + (TXR • TXDEPx) + (1TC • 1NV)X=, (15)
The present worth, or discounted cash flow, resulting from taxes
saved in year x would be:
DCFX = + NCFx/(l+r)x (16)
The total of all discounted cash flows over the economic life of
the equipment is the net present worth of the total tax savings.
NPW = x=? SDCFX = x_f ZNCFx/(l+r)x (17)
The tax depreciation method which yields the greatest NPW is
the method of economic choice.
Tables I through IV summarize the net present worth
calculations for four tax strategies currently permitted by the
Internal Revenue Service for amortizing the cost of pollution
control equipment, these being:
1. Straight Line Depreciation + 10% Investment Tax Credit;
2. Sum of the Year's Digits Depreciation + 10% Investment
Tax Credit;
3. Double Declining Rate Depreciation + 10% Investment
Tax Credit; and
4. Double Declining Rate Depreciation + Sum of the Year's
Digits Depreciation + 10% Investment Tax Credit
Any of the four tax strategies may be elected for amortizing
equipment which is subject to depreciation under Section 167 of
the Internal Revenue Code, and which have economic lives
greater than or equal to seven years. The calculations in each
table are based on equipment assumed to have an initial cost of
$1,000,000, an economic life of 10 years, and zero salvage value.
A discount rate of 5% has been assumed throughout.
A fifth tax strategy, Rapid Amortization + 5% Investment
Tax Credit, may be elected for amortizing the cost of certified
pollution control facilities over a 60-month period.
As defined by the IRS, a certified pollution control facility
means a new identifiable treatment facility which:
1. Is used in connection with a manufacturing plant or other
property in operation prior to January 1. 1976;
2. Is used to abate or control water or atmospheric pollution
or contamination by removing, altering, dispersing, stor-
ing, or preventing the creation or emission of pollutants,
contaminants, and wastes;
3. Has been certified by the appropriate state regulatory
agency that the facility has been designed and constructed
in conformity with the state program or requirements for
abatement or control of water or atmospheric pollution or
contamination;
4. Has been certified by the U.S. EPA as being necessary to
comply with either the provisions of PL 92-500, the
Federal Water Pollution Control Act, or with PL 91-604,
the Clean Air Act; and
5. Does not significantly increase the output or capacity,
extend the useful life, or reduce the total operating costs of
the manufacturing plant or property; or alter the nature of
the manufacturing or production process of the plant.
The election of this special depreciation method applies only
to treatment facilities that have economic lives less than or equal
to 15 years. If the economic life of the facility is greater than 15
years, the amortizable base is reduced in accordance with
equation 18.
Amortizable Base = Initial Capital
Cost • (15/Economic Life) (18)
The remaining portion of the initial capital costs of the
facilities may be amortized by any one of the four tax strategies
mentioned earlier over the full economic life of the facilities.
To elect the 5% investment tax credit, the facilities must have
an economic life of 5 years or more and the special 60-month
rapid amortization method must be used. The credit is based
upon 5% of the investment constituting the amortizable base.
Any portion of the full capital cost of the facilities that is not
eligible for the 5% credit is eligible, however, for the 10%credit.
Table 5 summarizes the net present worth calculation for this
special tax strategy. As before, the calculations are based on
equipment assumed to have an initial cost of $1,000,000, an eco-
nomic life of 10 years, and zero salvage value. A discount rate of
5% has again been assumed for these calculations.
Figure 2 summarizes the annual net cash inflows and total net
present worth of the tax savings resulting from each of the five
permissible tax strategies. For maximizing long term cash
inflows the accelerated method, DDR + SYD + 10% investment
-------
316 Financial Planning
Table I: Net Present Worth Calculations for Straight Line Deprectiation + Investment Tax Credit
Year
Depreciable
Base
Deprec iat ion
Rare
Before Tax
Depreciation
Net Cash
Flow
Discount
Factor
Discounted
Cash Flow
1
$ 1,000,000
10% ITC
$100,000
1.0500
$ 95,238
1
1,000,000
10%
$100,000
48,000
1.0500
45,714
2
10%
100,000
48,000
1.1025
43,537
3
10%
100,000
48,000
1.1576
41,465
4
10%
100,000
48,000
1.2155
39,490
5
10%
100,000
48,000
1.2763
37,609
6
10%
100,000
48,000
1.3401
35,818
7
10%
100,000
48,000
1.4071
34,113
8
10%
100,000
48,000
1.4775
32,487
9
10%
100,000
48,000
1.5513
30,942
10
10%
100,000
48,000
1.6289
29,468
= 100%
= $1,000,000
NPW =
+ $465,882
Table II: Net Present Worth Calculations for Sum of the Years Digit Depreciation + Investment Tax Credit
Year
Depreciable
Base
Depreciation
Rate
Before Tax
Depreciation
Net Cash
Flow
Discount
Factor
Discounted
Cash Flow
1
$ 1,000,000
10% ITC
$100,000
1.0500
$ 95,238
1
1,000,000
13.1818%
$181,818
87,273
1.0500
83,117
2
16.3636%
163,636
78,545
1.1025
71,243
3
14.5455%
145,455
69,818
1.1576
60,313
4
12.7273%
127,273
61,091
1.2155
50,260
5
10.9091%
109,091
52,364
1.2763
41,028
6
9.0909%
90,909
43,636
1.3401
32,562
7
7.2727%
72,727
34,909
1.4071
24,809
8
5.4545%
54,545
26,182
1.4775
17,720
9
3.6364%
;>6,364
17,455
1.5513
11,252
10
1.8182%
18,182
8,727
1.6289
5,358
= 100 %
= $1,000,000
NPW
* + $492,900
-------
Financial Planning
Table III: Net Present Worth Calculations for Double Declining Rate Depreciation + Investment Tax Credit
317
Year
Depreciable
Base
Equivalent
Depreciation
Rate
Before Tax
Depreciation
Net Cash
Flow
Discount
factor
Discounted
Cash Flow
1
$ 1,000,000
10% ITC
$100,000
1.0500
$ 95,238
1
1,000,000
20.000%
$200,000
96,000
1.0500
91,429
2
10.000%
160,000
76,800
1.1025
69,660
3
12.800%
128,000
61 ,440
1.1576
53,075
4
10.240%
102,400
49,152
1.2155
40,438
5
8.192%
81,920
39,322
1.2763
30,809
6
6.554%
65,536
31,457
1.3401
23,474
7
5.243%
52,429
25,166
1,4071
17,885
8
4.194%
41,943
20,133
1.4775
13,626
9
3.355%
33,554
16,106
1.5513
10,382
10
Adjusted
134,218
64,425
1.6289
39,551
= $1,000,000
NPW
= + $485,567
Table IV: Net Present Worth Calculations for Double Declining Rate Depreciation + Sum of the Years Digit Depreciation +
investment Tax Credit
Equivalent
Year
Depreciable
Base
Depreciation
Rate
Before Tax
Depreciation
Net Cash
Flow
Discount
Factor
Discounted
Cash Flow
1
$ 1,000,000
10% ITC
yioo.ooo
1.0500
$ 95,238
1
1,000,000
Dbl.Decl.Rate 20%
$200,000
96,000
1.0500
91,429
2
800,000
SYD 20.0000%
160,000
76,800
1.1025
69,660
3
17.7778%
142,222
68,267
1.1576
58,973
4
15.5555%
124,444
59,733
1.2155
49,143
5
13.3333%
106,667
51,200
1.2763
40,116
6
11.1111%
38,889
42,667
1.3401
31,839
7
8.8889%
71,111
34,133
1.4071
24,258
8
6.6667%
53,334
25,600
1.4775
17,327
9
4.4444%
35,555
17,066
1.5513
11,001
10
2.2222%
17,778
8,533
1.6289
5,239
= $1,000,000
NPW =
+ $494,229
-------
318 Financial Planning
Table V: Net Present Worth Calculations for Rapid Amortization + Investment Tax Credit
Depreciable
Base
Depreciation
Rate
Before Tax
Depreciation
Net Cash
Flow
Discount
Factor
Discounted
Cash Flow
1
$ 1,000,000
5% ITC
$ SO,000
1.0500
$ 4 7 , (> 1 9
1
1,000,000
20%
$200,000
96,000
1.0500
91,429
2
2 0%
200,000
9b,000
1.1025
87,075
3
20%
200,000
96,000
1.1576
82,930
4
20%
200,000
96,000
1.2155
78,980
5
20%
200,000
96,000
1.2763
75,217
6
-
0
0
-
0
7
8
-
0
0
0
0
_
0
0
9
-
0
0
-
0
10
0
0
-
0
100%
$1,0u0,000
NPW
= + $ 463,2.iO
600,GOO-
SCO,000--
400,000"
300,00 0-
200,000
~ 100,000'
" 90,000
O 80,000'
70,000
x 60,000
S 50,000
LJ 40.000
30.00 0
20,000
-RAPID AMORTIZATION+INV. TAX CREDIT
—O
TAX STRATEGY
RAPID AMORTIZATION+INV TAX CREDIT
DDR + SYD ~ INV TAX CREDIT
SYD + INV. TAX CREDIT
DDR + INV TAX CREDIT
STRAIGHT LINE + INV TAX CREDIT
2 4 6 8 10
ECONOMIC LIFE OF DEPRECIABLE ASSET (YEARS)
NET PRESENT WORTH
OF TAX SAVINGS
t 8 463,250
-I- S 494,229
+ S 492,900
+ $485,567
~ $ 465,882
Figure 2: Summary of Tax Strategies
-------
Financial Planning 319
Alabama
•
•
•
•
•
No Limit
•
•
• 1
Alaska
•2
Arizona
•
• <
Arkansas J
•
•
•
• 1
California
•
Colorado
• <
Connecticut
4
•
•
•
No I imii
•
•
Delaware
4
5
•
•
•
•6
Florida
• 7
•8
Georgia
•
•
•
•
•
Hawaii
5
•
•
•
•
• 9
Idaho
•
Illinois
•
-•
•
•
•
• '
Indiana
•
•
• '
Iowa
•
•
• 1
Kansas
•
• 1
Kentucky
•
• 10
Louisiana
1
5
•
• 1
Maine
•
•
•
•
• ' 1
Maryland
•
12
• 13
Massachusetts
•
No Limit
•
• '
Michigan
•
•
•
•
•
•
Minnesota
•
•
$50.0001 °
• 17
• '
Mississippi
• IS
#15
• '<>
•
• '
Missouri
•
•
•
• '
Montana
•
•
' 9
i n
•
• <
Nebraska
•?o
• 1
Nevada
•
•
New Hampshire
•
•
19
19
•
•
New Jersey
4
•
• 1
New Mexico
•
5
•
No Limit
•
• 29
New York
022
6
• 23
• 23
• 2.1
No Limit
• 25
• 25
• '
North Carolina
•
•
• 21
#21
•
•
• 1
North Dakota
•
5
•;-e
• 27
Ohio
•
•
•
•
•
• ~ I
•
Oklahoma
•
•
•
•
•
Oregon
•
•
19
19
•
50% ot
Facility Cost
• 2B
• <
Pennsylvania
•
•
•
•
•
• 29
Rhode Island
•30
•
•
•
•
20%/Year
• 31
South Carolina
A
•3 2
•
•
•
South Dakota
•
• '
Tennessee
• 4
•
•33
•
• '
Texas
Utah
• '
Vermont
•
•
•34
Virginia
•35
•35
• 36
•
• >
Washington
37
50% of
Investment
West Virginia
•
•
NoLtmit
•
•
Wisconsin
•
•
•
•
No Limit
•
Wyoming
•
•
• <
Puerto Rico
•
1—Industrial revenue bond issues.
2—State grants for municipalities only
3—Act 9 Industrial Revenue Bonds. The Act au-
thorizes municipalities and counties to issue
special obligalion revenue bonds to be used
for securing and developing industry. The
bonds may mature at any time up to 30 years
and may not carry an interest rate in excess
of flc/>
4—No state real estate tax is levied.
J>-No personal property tan is levied
6—May be included in industrial revenue bond
issues or state guaranteed bond issues in
certain cases.
7 —Pollution control devices are assessed at a
salvage commercial value.
8—City and/or county authority
9—Hawaii Capital Loan Program can assist up to
a maximum of 550,000
10—Municipal revenue bonds and Kentucky In-
dustrial Development Finance Authority loans.
11—Maine Industrial Building Authority loan
guarantees.
12—Taxed as machinery and equipment at 2%
rather than usual 4%.
13—Industrial revenue bonds and Maryland In-
dustrial Development Finance Authority loans
if pollution control equipment is part of a total
project.
14—Only affects public utilities
15—Exempt from ad valorem tax when financed
with pollution control bonds.
16—Absolute $50,000, with no refund.
17—Pollution control equipment is treated the
same as other capita} assets all of which are
eligible for accelerated depreciation.
18—When equipment is sold to a manufacturer,
rate is 1 % in lieu of 5%.
19—State does not levy sales tax.
20—Purchaser of water pollution equipment may
apply for sales tax refund.
21—New equipment is allowed a preferential rate
of 1K, with a maximum tax of 380 per article.
22—Buildings exempt from local real property tax.
No state or local ad valorem property tax is
levied
23—Pollution control equipment and utilities
which are pn integral part of the production
system are exempt from the state portion of
the sales tax and from any local sales tax ex-
cept that of New York City. Real estate is not
subject to the sales/use tax
24—Credit of up to 5 Vo of new investment in de-
preciable property (buildings and/or equip-
ment ) No limit, but credit may not cancel the
$250 minimum corporate income tax payable.
25—One-year write-off as an alternative to the new
investment credits described in footnote 24.
26—Credit is equal to 1 of gross expenditures
for wages and salaries during each of the first
3 years ot operation Credit is applicable to
any new facility, not just pollution control
equipment.
27—Jndustrial revenue bonds. Bank of North Da-
kota participation and statewide development
credit corporation.
28—No depreciation allowed in year credit is
taken
29—Industrial revenue mortgages and bonds may
be used.
30—State does not tax real estate Local units may
grant exemptions.
31— Industrial revenue bonds and Rhode Island
Industrial Building Authority loans.
32—Exempt for first 5 years.
33—May qualify for a reduced rate of tax.
34—State loan guarantees and revenue bonds.
35—Local option on certified equipment and
facilities.
36—Must be certified.
37—Washington has no sales tax exemption but
does have a sales tax deferral. The deferral
is for periods up to 3 years. Taxes are then
pro-rated and paid off over a period of up to 5
years. The program is applicable to pollution
control equipment if it equals 25% of the
value of capital investment already in place.
-igure 3: State Tax Incentive
and Financing Programs
for
Pollution Control
-------
320 Financial Planning
tax credit, is clearly the economic choice. Because this method
may also be elected for amortizing the cost of facilities asso-
ciated with manufacturing process changes to abate pollution,
this tax strategy may be the optimum for most pollution control
projects. Curiously, the special pollution control tax strategy,
rapid amortization + 5% investment tax credit was the least
attractive. If, however, management's financial objective was to
minimize short-term profit impairment, or maximize short-term
cash inflows, this tax strategy will generally be the optimum eco-
nomic choice. It must be emphasized, however, that excluding
the difference in the investment tax credit, the total taxes paid by
a firm over the economic life of the pollution control equipment
will be identically the same regardless of the tax strategy
employed. The difference between each strategy lies in the
schedule governing the payment of these taxes.
The tax benefits discussed thus far are forms of indirect assis-
tance provided by the federal government to soften the eco-
nomic impact of capital expenditures in pollution control
equipment. Indirect assistance in the form of property tax
exemptions, sales and/or use tax exemptions, franchise tax
exemptions, tax credits, and accelerated depreciation methods
are also available in many states as an incentive to management
to install pollution control equipment. If applicable, the effect of
these tax benefits on cash flow should also be included in the
analyses presented above. Figure 3 summarizes the pollution
control tax incentive programs available to industry in each of
the 50 states.
Step 5: Identification and Evaluation of Sources of
Project Financing
Few firms have sufficient cash assets to pay for the costs
associated with the design and construction of full scale
pollution abatement facilities. Expenditures of this nature
generally require that management must borrow the monies
necessary to pay for all or at least a portion of the facility capital
costs. Borrowed money must be repaid with interest, the amount
of which will be a function of the interest rate and the term over
which the principal is repaid. This repayment of principal and
interest constitutes a major source of cash outflows associated
with many pollution control projects.
Interest amounts, like depreciation amounts, are accounted
for as expenses and are, therefore, tax deductible.
Consequently, the net cash outflow in any year x resulting from
the repayment of the principal and interest on a loan in that year
may be expressed as follows:
NCFX = — [ (P+I) — (IT) ] x (19)
or
NCFX = - PX~IX(1-T) (20)
where Px = Principal payment in year x (dollars)
Ix = Interest payment in year x (dollars)
T = Corporate tax rate (%/100)
The present worth, or discounted cash flow, of the loan
repayment in year x would be:
DCFX = NCFx/(l+r)x (21)
The sum total of all discounted cash flows over the term of the
loan, n, is the net present worth of the loan:
NPW = - x=f S DCFX = - xmf S NCFx/(l+r)x (22)
The financing method which results in a loan with the smallest
net present worth is the method of choice.
The three most common sources for obtaining funds to
finance the capital costs of pollution abatement facilities are: (1)
commercial bank loans, (2) tax exempt bonds, and (3) direct
loans from the Small Business Administration. Each of these
sources of financing will be discussed and evaluated in the
following paragraphs.
Commercial Bank Loan
Many large commercial banks will loan monies to industry, at
preferential rates and terms, for expenditures in pollution
control facilities. At this time, the interest rate on most pollution
control loans secured through a bank average approximately 8
Zi% per year. The interest amount is computed on the declining
unpaid balance of the principal. Repayment periods will vary
depending on the size of the loan and the credit rating of the firm
borrowing the money. Repayment schedules generally consist of
uniform quarterly or annual payments.
The major advantage of this source of financing is that there
are no federal or state restrictions on pollution control loans
secured through a bank. The magnitude, interest rate, repay-
ment period, and repayment schedule of the loan are mutually
established by representatives from the bank and the firm
borrowing the money. The major disadvantages associated with
this source of financing are: (1) the pollution control facilities
themselves are generally not acceptable as collateral, and (2) the
interest rate on this loan is generally higher than on loans
secured through the sale of tax exempt bonds, or the Small
Business Administration.
Table VI summarizes the net present worth calculations for a
typical pollution control loan from a commercial bank. The
calculations are based on a loan of $1,000,000 to be repaid over
20 years at an interest rate of 8 [/i% per year. The corporate tax
rate and after tax rate of return were assumed to be 48% and 5%,
respectively.
Tax Exempt Bonds
Under the Revenue and Expenditure Act of 1968, pollution
control facilities for private firms can also be financed by local
governmental units through the sale of low interest tax free
bonds commonly known as industrial development bonds.
Where permitted by state law the governmental units allowed to
issue industrial development bonds include cities, towns,
boroughs, townships, villages, quasi-governmental authorities,
or the state itself. The sources which loan the money to these
governmental units, through the purchasing of the bonds, may
include the general public, a bank, a private investment firm, or
anyone wishing to benefit from a tax free income. These funds
are then turned over to the firm to pay for the pollution control
facilities.
The Internal Revenue Service restricts the amount of funding
which can be secured through tax free bonds for many industrial
production or manufacturing facilities, but there is no limit on
the amount of funds which can be secured for facilities to abate
air pollution, water pollution, or solid wastes. The proposed
facilitiesto be funded however, may not decrease production
costs or increase production capacity except for solid wastes
where recycling facilities are allowed.
In tax exempt financing two types of repayment arrange-
ments are common. In the first type, known as installment
financing, the facilities are leased to the firm owning the plant
whose pollution is being abated. The firm then makes uniform
lease payments to the governmental unit each year which in turn
uses these funds to pay the principal and interest on the bonds.
When the bonds are retired, title to the facilities is turned over to
the firm. In the second type, the firm pays equal interest
payments each year but differing amounts of principal into a
sinking fund throughout the term of the loan. The sinking fund
plus all earned interest is used as the repayment source at the end
-------
Financial Planning 321
Table VI: Net Present Worth Calculations for Bank Financing
Net Cash
Discount
Discounted
Year
Principal
Interest
Principal
Interest
Flow
Factor
Cash Flow
1
$50,000
$85,000
$ 9,625
$85,000
$ 53,825
1.0500
$ 51,262
2
50,000
80,750
13,875
80,750
55,865
1.1025
50,671
3
50,000
76,500
18,125
76,500
57,905
1.1576
50,022
4
50,000
72,250
22,375
72,250
59,945
1.2155
49,317
5
50,000
68,000
26,625
68,000
61,985
1.2763
48,566
6
50,000
63,750
30,875
63,750
64,025
1.3401
47,776
7
50,000
59,500
35,125
59,500
66,065
1.407i
46,951
8
50,000
55,250
39,375
55,250
68,105
1.4775
46,095
9
50,000
51,000
43,625
51,000
70,145
1.5513
45,217
10
50,000
46,750
47,875
46,750
72,185
1.6289
44,315
11
50,000
42,500
52,125
42,500
74,225
1.7103
43,399
12
50,000
38,250
56,375
58,250
76,265
1.7959
42,466
13
50,000
34,000
60,625
34,000
78,305
1.8856
41,528
14
50,000
29,750
64,875
29,750
80,345
1.9799
40,580
15
50,000
25,500
69,125
25,500
82,385
2.0789
39,629
16
50,000
21,250
73,375
21,250
84,425
2.1829
38,676
17
50,000
17,000
77,625
17,000
86,465
2.2920
37,725
18
50,000
12,750
81,875
12,750
88,505
2.4066
"36,776
19
50,000
8,500
86,125
8,500
90,545
2.5270
35,831
20
50,000
4,250
90,375
4,250
92,505
2.6533
34,894
=
$1,000,000
= $892,500 =
$1,000,000
-- $892,500
NPW =
- $871,695
Annual payments = $1,892,500/20 = $(J4,(>25
Table VII: Net Present Worth Calculations for Industrial Development Bonds
Net Lasn
Discount
Discounted
Year
Principal
Interest
Principal
Interest
Flow
Factor
Cash Flow
1
$ 0
$70,000
$ 0
$66,200
$ 44,024
1.0500
$ 41,928
2
0
70,000
0
46,200
24,024
1.1025
21,790
3
0
70,000
0
46,200
24,024
1.1576
20,753.
4
50,000
70,000
50,000
46,200
74,024
1.2155
60,900
5
50,000
66,500
50,000
46.200
74,024
1,2763
57,999
6
50,000
63,000
50,000
46,200
74,024
1,3401
55,238
7
50,000
59,500
50,000
46,200
74,024
1.4071
52,607
8
50,000
56,000
50,000
46,200
74,024
1.4775
50,101
9
50,000
52,500
50,000
46,200
74,024
1.5513
47,717
10
50,000
49,000
50,000
46,200
74,024
1.6289
45,444
11
50,000
45,500
50,000
46,200
74,024
1.7103
43,281
12
50,000
42,000
50,000
46,200
74,024
1.7959
41,218
13
50,000
38,500
50,000
46,200
74,024
1.8856
39,257
14
50,000
35,000
50,000
46,200
74,024
1.9799
37,388
15
50,000
31,500
50,000
46,200
74,024
2.0789
35,607
16
50,000
28,000
50,000
46,200
74,024
2.1829
33,911
17
50,000
24,500
50,000
46,200
74,024
2.2920
32,297
18
50,000
21,000
50,000
46,200
74,024
2.4066
30,759
19
50,000
17,500
50,000
46,200
74,024
2.5270
29,293
20
200,000
14,000
200,000
46,200
224,024
2.6533
84,432
$1,000,000
$924,000
$1,000,000
NPW =
- $861,920
Avg. Interest/Year = $924,000/20 = $46,200
-------
322 Financial Planning
of the term of the financing. When the bonds are retired, title to
the facilities is again turned over to the firm.
Table VII summarizes the net present worth calculations for a
pollution control loan obtained through the sale of tax exempt
bonds based on the second type of repayment arrangement. The
calculations are based on a loan of $1,000,000 to be repaid over
20 years at an interest rate of 7% per year. The total interest
amount to be repaid was computed on the basis of the declining
unpaid balance of the principal. The repayment schedule for the
principal and interest was assumed to be as follows:
Principal: 0% for the first three years
5% for the next sixteen years
20% in the last year
Interest: Equal annual payments
A 2% underwriting fee payable to the governmental unit for
administering the sale of the bonds has been added to the
repayment interest in the first year. The corporate tax rate and
after tax rate of return were again assumed to be 48% and 5%,
respectively.
Small Business Administration Loan
A second source of government aid financing available to
industries required to install pollution control facilities is a
direct loan from the Smali Business Administration. The Clean
Air Act, PL 91-604, and the Federal Water Pollution Control
Act Amendments of 1972, PL 92-500, authorized the SBA to
make loans to assist small businesses in adding to or altering
their equipment, facilities, or methods of operation in order to
meet the pollution abatement requirements of either Act. A
prerequisite to receiving such a loan is a written statement from
the U.S. Environmental Protection Agency and appropriate
state regulatory agency certifying that the adidtions, alterations
or methods of operation are necessary and adequate to comply
with the mandated pollution abatement requirements.
SBA loans are available only to businesses that are independ-
ently owned and operated and meet employment and/or sales
standards established by the agency. Loans from this source are
not available to businesses if financing can be secured through
other sources.
At this time the current interest rate on loans secured through
the SBA is 6-Ys% per year. The maximum amount of a loan
currently available for any purpose is $150,000. The total
interest amount iscomputed on the basis of the declining unpaid
balance of the principal. Repayment periods up to 30 years are
available, but most loans are financed over a period of 20 years
or less. Repayment schedules generally consist of equal annual
payments.
Table VIII summarizes the net present worth calculations for
a typical pollution control loan from the SBA. The calculations
are again based on a loan of $1,000,000 (although this exceeds
the maximum amount currently available from the agency) to be
repaid over 2 years at an interest rate of 6-Ys% per year.
The corporate tax rate and after tax rate of return were again
assumed to be 48% and 5%, respectively.
Figure 4 summarizes the annual and net present worth values
of the cash outflows for each of the three financing strategies
illustrated here, The direct loan from the Small Business
Administration would be the superior financing method
because it resulted in the minimum net present worth value.
Because of the eligibility requirements and loan limitations
associated with this source of funding, SBA financing may not
be available for many pollution control projects. In such cases,
the sale of tax exempt bonds would probably be the most eco-
nomically attractive source of funding.
Step 6: Analysis of Engineering Alternatives
The previous steps in the financial planning process consisted
essentially of identifying and quantifying various types of cash
inflows and outflows associated with a particularengineeringal-
ternative. Cash inflows would include revenues which may be
generated as a result of implementing a particular alternative, or
tax refunds which may result from the election of a specific tax
strategy. Cash outflows would include financing payments,
capital and annual project costs, and annual tax payments. In
this step we wish to analyze the cash flow pattern associated with
each identified alternative so that the most cost-effective
treatment and control arrangement can be selected.
6 8 10 12 14
TERM OF LOAN (YEARS)
FINANCING STRATEGY
SBA LOAN
TAX EXEMPT BONDS
BANK LOAN
NET PRESENT WORTH
OF CASH OUTFLOWS
- fc 848,509
" S 86 1,920
- 8 871,696
Figure 4: Summary of Financing Strategies
A computer program, developed by the authors, permits the
analysis of any proposed pollution control project using the
present worth discounted cash flow method. A brief description
of the major features of the program follows:
Financial Analysis
The magnitude, interest rate, term, and repayment schedule
of the loan, and the corporate tax rate and after tax rate of
return are specified and the net present worth of the financing
strategy is determined. The calculations performed are identical
to those described in Step 5.
Capital Expenditures Analysis
The initial investment, revenue stream, operating expense
stream, taxation parameters, and depreciation characteristics
are specified and the net present worth of the capital expendi-
tures scheme is determined. The calculations performed are
similar to those described in most finance books.
The input parameters for the program and their limitations
are set forth below:
-------
Financial Planning 323
General Information
YCONB - Year construction begins.
- Duration of construction in years. DCN
must not exceed 10.
- Economic life in years of facility after
operations begin. DCN + EL must not
exceed 50.
- After tax rate of return in decimal form.
Would be less than 1.0 except in very
unusual case.
- Total investment in dollars.
DCN
EL
ROR
INV
Financing Information
ROI
LEN
POC
PRINC
PRIN1
ESPR
PRIN(l) . . .
PRIN(LEN)
Annual interest rate on the loan expressed
in decimal form.
Term of the loan in years.
Principal repayment option code: (1) con-
stant yearly principal payments; (2) each
year principal repayment is increased by a
fixed rate over the previous year; (3) prin-
cipal payments vary from year to year
over the term of the loan.
Constant yearly principal payments .
POC = 1 only
First year principal payment . POC = 2
only
Principal repayment escalation rate .
POC = 2 only
III.
List of yearly principal repayments in
sequence. The total number input must be
equal to the value of LEN. POC = 3 only.
Revenue Information
ROC
REVC
REV1
ESRT
REV(l). .
REV(EL)
Revenue option code. (1) constant yearly
revenue over economic life; (3) each year
revenue is increased by a fixed rate over
previous year; (3) revenue varies from
year to year over economic life.
Constant yearly revenue. ROC = 1 only.
First year revenue. ROC = 2 only.
Revenue escalation rate in decimal form.
ROC = 2 only.
List of yearly revenues in sequence. The
total number input must be equal to the
value of EL. ROC = 3 only.
IV. Capitalization Information
The input of the funds invested in the project may occur in steps
over the construction period. For each construction year and for
the first year of operations, the program will request the fraction
(PCINV) of the total investment input at the beginning of that
year.
V. Operating Expense Information
OEXC
OEX
OEX1
OERT
OEX(l).
OEX(EL)
Expense option code. (1) constant yearly
expenses over economic life; (2) each year
expenses are increased by a fixed rate over
previous year; (3) expenses vary from year
to year over economic life.
Constant yearly expenses. OEXC = 1
only.
First year expenses. OEXC = 2 only.
Expense escalation rate in decimal form.
OEXC = 2 only.
V.
- List of yearly expenses in sequence. The
total number input must be equal to the
value of EL. OEXC = 3 only.
Tax and Depreciation Information
TXR - Tax rate in decimal form.
NDS
TCR
TCAMT
TXDEP
BKDEP
DPL
DEPPC
SVPC
- Number of depreciation segments into
which the project is separated. NDS must
not exceed 10.
- Investment tax credit rate in decimal
form.
- Fraction of total investment applicable
for investment tax credit. TCAMT must
not exceed 1.0.
For each of the depreciation segments, the
program will request the depreciation
characteristics. These include the follow-
ing:
- Tax depreciation code. (0) not deprecia-
ble; (1) straight line; (2) sum of the year's
digits; (3) double declining; and (4) rapid
amortization.
- Book depreciation code. 0, 1,2, 3, or 4 as
described above.
- Depreciation life in years.
- The initial value of that depreciation seg-
ment as a fraction of the total investment.
Note that the sum of all DEPPC's for the
NDS segments must be 1.0.
- The salvage value of that depreciation seg-
ment as a fraction of the total investment.
The sum of all SVPC's cannot exceed 1.0.
Following the completion of all calculations, a summary of
the results and pro forma financing and capital expenditures
cash flow schedules are printed. Printouts from the program are
included with the sample problem presented in the last section of
the paper.
Step 7: Selection of the Most Cost-Effective Engineering
Alternative, Tax Strategy, and Source of Financing
Given the financing and capital expenditures cash flow sched-
ules for each alternative, the selection of the most cost-
effective treatment and control arrangement can readily be
determined. If management's financial objective was to minim-
ize long-term profit impairment, the engineering alternative,
source of financing, and tax strategy resulting in the minimum
net present worth are the economic choices. If management's
financial objective was to minimize short-term profit impair-
ment, annual net cash flows for both the financing and capital
expenditure schemes for each alternative are totaled over the
first three to five years of the project. The engineering alterna-
tive, source of financing, and tax strategy resulting in the
minimum total cash outflow or maximum total cash inflow over
that period are the economic choices. If management's financial
objective was to minimize peak cash outflows, annual net cash
flows are totaled over the entire life of the project. The
engineering alternative, source of financing, and tax strategy
which results in the minimum cash outflow in any year are the
economic choices.
Application of the Financial Planning Process
An industry located in a large metropolitan area is currently
discharging untreated sanitary and process wastewaters to a
nearby river. The U.S. Environmental Protection Agency and
state regulatory agency have recently ordered that the continued
discharge of raw wastewaters to the river will no longer be
allowed. An engineering firm has been retained to seek out the
most cost-effective wastewater treatment and control scheme.
Following a comprehensive industrial wastewater survey, and
various other investigations, the engineering firm has identified
and developed preliminary bases of design and capital and
annual cost estimates for three technically feasible alternatives:
-------
324 Financial Planning
Table VIII: Net Present Worth Calculations for SBA Financing
Year
Principal
Net Cash
0 i scount
0 i scounted
Interest
Princ ipal
Interest
1' 1 ow
Factor
(.ash Flow
$ 64,844
61,756
58,817
56,015
1
$50,000
$66,250
$50,000
$34,781.25
$68,086.25
1.0500
2
50,000
62,937.5
50,000
34,781.25
68,08 6.25
1.1025
3
50,000
59,625
50,000
34,781.25
68,08 6.25
1.1576
4
50,000
56,312.5
50,000
34,781.25
68,086.25
1.2155
5
50,000
53,000
50,000
34,781.25
68,086.25
1.2763
53,347
50,807
48,388
46,082
43,890
6
50,000
49,687.5
50,000
34,781.25
68 ,086.25
1.3401
7
50,000
46,375
50,000
34,781 .25
68,086.25
1.4071
8
50,000
43,062.5
50,000
34,781.25
68 , 08 6.25
1.477 5
9
50,000
39,750
50,000
34,781.25
68,086.25
1.5513
10
50,000
36,457.5
50,000
34 ,781.25
68,086.25
1.6289
41,799
11
50,000
33, 125
50,000
34,781.25
68,086.25
1 . 71 03
39,810
12
50,000
29,812.5
50,000
34,781.25
68,086.25
1.7959
37,912
36,109
13
50,000
26,500
50,000
34,781.25
68 , 08 6.25
1.8856
14
50,000
23,187.5
50,000
34,781.25
68,086.25
1.9799
34,389
15
50,000
19,875
50,000
34,781.25
68,086.25
2.0789
32,751
31,191
29,706
28,291
26,944
25,661
- $848,509
16
50,000
16,562.5
50,000
34,781.25
68 , 086.25
2.1829
17
50,000
13,250
50,000
34,781.25
68 ,086.25
2.2920
18
50,000
9,937.5
50,000
34,781 .25
68,086.25
2.406o
19
50,000
6,625
50,000
34,781.25
68,086.25
2.5270
20
50,000
3,312.5
50,000
34,781.25
68,086.25
2.6533
$695,625
NPW =
Avg. Interest/Year = $34,781.25
Alternative #1
Complete treatment and discharge of treated wastes to the
river. Tertiary treatment facilities will be required in order to
meet federal and state effluent limitations. Estimated capital
and annual costs are as shown in Table 9.
A Iternative #2
Partial treatment and discharge of pretreated wastes to the
municipal collection system. Secondary facilities would be
provided to lower raw wastewater quality to domestic levels.
Estimated capital and annual costs are as shown in Table 9.
Alternative #3
No treatment; discharge of raw wastes to the municipal
collection system. Estimated annual costs are as shown in Table
9.
Management has determined that for this project it wishes to
maximize long-term profit. The current corporate tax rate and
after tax return are 48% and 5%, respectively. Additional
general information related to alternatives #1, and #2 is set forth
below:
1. Construction of facilities could begin on January 1,1978.
2. Duration of construction is estimated to be two years; eco-
nomic lives are assumed to be 20 years.
3. Corporate funds will be invested in accordance with the
following schedule:
1978—60% of the capital costs
1979—30% of the capital costs
1980—10% of the capital costs
4. Financing will be secured through the sale of 20-year tax
exempt bonds. The rate of interest to be paid on the bonds
is 7%/year. The underwriting fee will be 2% of the bond
issue. Repayment of the principal and interest on the
bonds will be in accordance with the following schedule:
Principal: First 4 years: Zero
Next 15 years: 5% of the bond issue
Last year: 25% of the bond issue
Interest: Equal annual payments
5. Facilities will be amortized in two segments:
Segment 1:75% of the capital costs amortized over the first
5 years of operation.
Segment 2:25% of the capital costs amortized over the full
20-year economic life using the sum of the year's digits
depreciation method.
5. An equivalent investment tax credit of 6.25% of the full
capital cost of the facilities will be elected in 1980, the first
year of operations. The equivalent ITC is computed as
follows:
Equivalent ITC = [(0.05X0.75) + (0.10)(0.25)]/1.00 =
0.0625
Analysis
Pro forma financing and capital expenditure cash flow sched-
ules for each of the three alternatives is presented in Tables 10,
11, and 12. In each table annual cash outflows resulting from the
repayment of the 20-year tax exempt bond issue are tabulated
under the column heading "net cash flow". Annual cash inflows
or outflows resulting from the capital and annual operating
costs associated with a particular alternative are tabulated under
the column heading "gross cash flow". The year-to-year total of
these two columns of figures in each table represent the total
annual net cash inflow or outflow for each alternative. Figure 5
is a plot of these total annual net cash flows.
The cash flow profiles for alternatives #1 and #2 are very
similar in shape, differing only slightly in magnitude over their
economic lives. For both, large cash outflows result in 1978 and
1979 due to the investment of capital funds necessary for the
construction of the proposed facilities. In 1980, the first year of
facility operations, a net cash inflow results for alternative #1
due to the election of the investment tax credit. A net cash inflow
-------
Financial Planning 325
lor both alternatives occurs in 1981 because the tax refund
resulting in that year, due to the election of the rapid amortiza-
tion tax strategy, is slightly greater than the financing payment
in that year. Beyond 1981, however, principal on the bond issue
must be repaid and this repayment far exceeds the tax savings
resulting from the rapid amortization and sum of the year's
digits tax strategies. The peak cash outflow in 1977 is due to the
repayment of the remaining 25% of the principal on the bond
issue.
The cash flow profile for alternative #3 is simply a plot of the
gross cash flow figures shown in Table XII.
Table XIII summarizes the net present worth values for each
alternative. Since management's financial objective was to
maximize long-term profit, the alternative with the minimum
net present worth is the most cost-effective treatment and
control arrangement. Alternative #3 is therefore the economic
choice. Note, however, that if financing had not been consid-
ered in the comparison of these alternatives, alternative #2
would have been the economic choice.
The calculations for minimizing short-term profit impairment
are summarized in Table XIV. For this objective annual net cash
inflows and outflows are added algebraically over the short-
term life of the project, assumed here to be five years. The alter-
native which results in the lowest net total outflow or greatest
net total inflow of cash over that period is the economic choice.
Again alternative #3 is the economic choice.
The calculations for minimizing peak cash outflows are sum-
marized in Table XV. For this objective, alternatives would be
compared on the basis of minimum peak cash outflows in any
one year. Again alternative #3 is the most favorable alternative.
SUMMARY
A systematic procedure is presented to aid both engineers and
management in two areas of decision making common to the
consideration of all proposed pollution control projects: (1) the
financing decision, i.e., where should the capital funds for the
proposed project be obtained, and (2) the capital expenditure
decision, i.e. which of several technically feasible alternatives is
most acceptable in terms of the financial policies and goals of the
company. The procedure consists essentially of the identifica-
tion, quantification, and analysis of cash inflows and outflows
associated with each alternative. Cash inflows would include
revenues which might possibly be generated as a result of
implementing a particular alternative, or tax refunds which may
result from the election of a specific tax strategy. Cash outflows
would include financing payments, capital and annual project
costs, and annual tax payments. The analysis presented here is
based on the present worth financial technique. By means of this
technique, the cash patterns associated with each alternative can
be analyzed, and the most cost-effective engineering alterna-
tive, source of financing, and tax strategy selected.
REFERENCES
1. Horngren, C. T., Cost Accounting: A Managerial
Emphasis; Prentice-Hall, Inc., 1967.
2. Marshall, C. and Commins, J., "Choosing Optimum
Financial Strategies for Pollution Control Systems," EPA
Technology Transfer Seminar Publication No. 625-3-76-
005, June, 1976.
3. Quirin, C. D., The Capital Expenditure Decision; Richard
D. Irwin, Inc., 1967.
4. van Home, J. C., Financial Management and Policy,
Prentice Hall, Inc., 1971.
5. Weston, J. F. and Brigham, E. F., Managerial Finance,
Holt, Rinehart and Winston, 1969.
Table IX: Estimated Capital and Annual Costs for Engineering Alternatives
Alternative #1
Alternat ive
#2
Alternative
#3
Year
Capita 1
Annual
Capita 1
Annual
Capital
Annual
Costs
Costs
Costs
Costs
Costs
Costs
1978
$4,500,000
$3,000,000
1979
2,250,000
1,500,000
-
_
1980
750,000
$225,
000
500,000
$382,000
_
$ 710,000
1981
-
236,7 50
-
390,750
_
710,000
1982
-
247,
500
-
399,500
710,000
1983
-
258,
7 50
-
408,250
-
710,000
1984
-
270,
000
-
417 ,000
_
710,000
1985
-
281
250
-
482,750
_
911,000
1986
-
292,
500
-
491,500
_
911,000
1987
-
303,
7 50
-
500,250
911,000
1988
-
315,
000
-
509,000
911,000
1989
-
326,
250
-
517,750
_
911,000
1990
-
337,
500
-
600,500
1,172,300
1991
-
348,
7 50
-
609,250
_
1,172,300
1992
-
3(>0,
000
-
618,000
_
1,172,300
1993
-
371
250
-
626,750
_
1,172,300
1994
-
382,
500
-
(>35, 500
1 ,172,300
1995
-
393,
7 50
-
740,680
_
1,511,990
1996
-
405,
000
-
749,430
_
1,511,990
1997
-
416,
250
-
7 58,380
_
1,511,990
1998
-
427,
500
-
766,930
_
1,511,990
1999
. " -
438,
750
~
775,680
-
1,511,990
-------
326 Financial Planning
Table X: Financing and Capital Expenditures Cash Flow Schedules Alternative #1
*******
*******
TOTAl llWESTMENT ( DOLLARS) 7500000.00
PRESENT WCPTH OF FINANCING SCHEME
PRESENT KLRTH OF CAPITAL EXPENCITURES
NET PHtScNT worth OF PROPOSED PROJECT
-64 3 335*), 00
-6053757.00
- 12^87113,00
FLCW FCft
FINANCING
VEAP
PP INCIPLE
INTEfcbST
****
********
1978
0.0
-367499 .00
1Q79
0.0
-367499 .00
1980
0.0
-367499.00
1981
0.0
-367499 .00
1982
-375000.00
-367499.00
1983
-i 75000.00
-36749 9.00
1984
-375000.00
-367499.00
1985
-375000.00
-367499.00
1 9 Ht
- 375000.00
-367499.00
1987
-375000.00
-367499.00
198«
- 375O00.00
-3674S9.00
1989
-375000.00
-367499.00
1990
-375000.00
-367499.00
1991
-375000.Ou
-367499.00
1992
-375000.00
-367499.00
1993
-375000.00
-367499.00
1994
- .375000. uQ
-367«*S9.00
} 9^5
- j>75000 .0 0
-367499.00
1996
-375000.00
-36749S.CC
1 9 9 7
-1675000.00
-367499.00
TCT fLS
-7500000.00
- 73499 ei.00
Nt T CASH
D I SCOUNT
01SCCUNTEC
FLOW
PACTO«
Cash PLCih
********
********
**********
-341099.44
1 .0500
-3 2 4 8S6 . 31
-1S1QS9,50
I . 1 0 ? 5
-173233.13
- 191099. 50
1.1576
-l6t>07<3.3;
-191C<39. ^0
1 .215-5
-157^18.44
-566C99.50
1 .2 763
-443555.^4
-566099.50
1.3401
-422434.00
-566C99.50
1 .407 1
-402318.44
-566C99.50
1 .477-4
-3ttMbJ.6c
-566C99.50
1.5513
-364915.13
-566C99.50
1 .6289
- 3 4 7 c 3 3 . 5 t
-5fc6C39.7 5
-566C^9.5C
2.?c20
-6,00
cash flc,w *-cp capital exptNDiTuof.s
vEAft
RiV£$r*cNT
Pc VfcN'JF
****
(*,»***•*«
*«•***»
I 97b
4499999.00
0.0
1979
2249999.00
u.u
1980
749999.69
0.0
' 9hl
0.0
0.0
1982
0.0
0.0
19P3
0.0
0.0
1 9 P 4
0.0
0.0
1 9 b 5
0.0
0.0
1 9Pfc
0.0
0.0
19 % 7
0.0
0.0
19 38
O.U
0 . 0
1989
0.0
0.0
1990
O.U
o* u
1991
O.U
O.U
199?
0.0
0.0
1993
0.0
G.O
1994
0.0
0.0
1 9 9 5
0.0
0.0
190*
u.o
0.0
1997
0.0
0.0
1998
0.0
0.0
1999
0.0
0.0
GPuSb CA'jH
AOJOSltO CASH
P1SC OUNt
0 t 5C OUNTtD
FLOW
«¦ LOW
f Al tq*
CASH Fl OW
*»»»*•*»«¦/»
••«»***«»*»*»
«**•«»«•
**********
-4* 99999.JO
-<•499999.00
1 . JOOO
"~499994.jj
-.224^^,00
-??4*999.00
0.^524
-il42H57.uo
2 2 74*4 . -U
197252. 7S
0.9070
17 6914.25
4QB57h.Uf-
4|?4H4.75
0 . <*6 i P
h1 678<», 25
h984*|2.63
4 7 2 . 1',
0 . H22 7
^ dd 798.31
4 783<<*.f-9
46?()H 7 . 1 1
0 . 7tt U
36252^.6;»
4*0 I 7 1 . <"»
452 7hh .
0 . 7 4 o 2
337M79.06
-8196*.$H
-Hi 119. 13
0.7107
- 5 7o 50. 1 1
-42 1 l)().0^
-9 101 7 .rth
0.6768
-61604.RO
-1 u ?; < s. n i
-lU09i6.Hl
J.6 44 h
-6^052.26
-1 12371.*0
- 1 1 06 1 5 . (vj
0.6139
-68031.63
-I22.5u7.25
-12uM4.5(J
0.584 7
-7J579.75
- 1324+2.94
- 1 >U0 ] 3 , ¦> 1
0.5S6 8
- 7? 7 30. 94
- 142 77H.69
-14051?.19
J. "530 3
-74517.19
-l.VX/U.Jl
-:t-o4io.t-4
O.SO^l
- 75968.3H
- ! 6® OJ?u . 00
- W 0 3 0 9 . H I
0.4810
-77U2.Jo
-! Mlh*.*'l
-I 7l)?UH.t s-
0 . 4 5 H 1
- 7 79 75, 31
- 1 83 3? 1 . 5(»
-1B0107.56
0 . 4 J #, ^
-TdSei.19
- 1 9845-7.19
-lc000b.44
0 . 4 1 5 S
-78952,50
,V4
-19«,J05. 31
0.3957
- 791 10.25
-213 72H.63
-2096.04. 1?
0.3769
-79073.94
-22 3 H*.4 . 3 1
-219702.94
0. 358'i
- 7 R 861.75
TCTAlb 74^9997.00
66375C0.00 72547 *h.)0 - <*• H H? "*4 0 . 00
- t>05 3 73« • 00
-------
Financial Planning 327
Table XI: Financing and Capital Expenditure Cash Flow Schedules Alternative #2
SUMNARY
*******
TOT &L
iNVLSTHENT 10LLLARS)
5000000.
00
PRh Sf-NT
hORTH OF FINANCING SChfcMf
-4288900.
00
P«£ ScNT
WOKTh OF CAPITAL FXPfcNOITURES -5993052.
00
NFT PhESENT WLJOTh OF
PPGPOSED PkQJfcCT -10282652.
00
CASH CLCw
Flh
f1NANC1NG
YEAP
HRINClPLE
interest
NET CASH
DISCOUNT riSCOUNTEC
c LOW
FACTOR
CASH HOW
* * « *
*********
********
********
******** **********
1978
0.0
-244990,06
-22739«.50
1.0500
21t.571.06
1979
0.0
-24*999 .06
-127399.56
1.1025
115555.31
1980
0.0
-244999.06
-127399.56
1.1576
1 10052.75
1901
0 .0
-244999 .06
-127399.56
1.2155
104812.19
1*B2
-^5UOOO .00
-2 4 4 9 9 S . 06
-377399.56
1.2763
205703.56
19 63
-250000 .00
-244999.06
-377399.56
1.3401
2*1622.56
1^84
-2 50000 .00
-244999.06
-377399.5o
1.4071
2t 9212.19
1986
-250000.00
-244999 .06
-377399.56
1.4774
255440.38
I9fi*
-250000 . UO
-244999.06
-377399.56
1.5513
243276.69
1 9 ft 7
-250U00 .00
-244999.06
-377399.56
1.6269
231692.31
19P8
-c50000.00
-244999.06
-377399.56
X . 7103
220659.50
1969
—^50000.00
-244999.06
-377399.56
1.795o
210152.06
1*00
- 250000 .00
-244999.06
-377399.56
1.8856
2001*4.Pd
19-51
-250000 .00
-244999 .06
-377399.56
1.9799
190614.38
1992
-250000 .00
-244999.06
-37739S.56
7.0789
1B1537.63
1993
-25u000 .00
-244999 .06
-377399.56
2.1928
172893.06
1«94
-250000.00
-244999.06
-377399.56
2.2920
164660.25
1995
-250000.00
-244999.06
-377399.56
? . 4066
156819.31
l«96
-250000.00
-244999.0t
-377399.56
2.52S9
149351.88
1997
-1250000.00
-244999.06
- 13 7 7 399.CO
2.6533
519134.8P
tctals
-5000000 .00
-<*899982 .00
-4284900.00
CASH FLOW
FLft
CAPITAL EXPENDITURES
YEAR
INVESTMENT
REVENUE
OPERATING TAX
gross cash
AOJUSTtC CASH
OISCOUNT
01SCOUNTEO
EXPENSES pai^
clCw
F L CW
*ACT0C
CASH FLOW
****
**********
*******
********* ****
**********
*************
********
***** *****
1978
2999999.00
0.0
0.0 0.0
-2999909.00
-2990999.00
1.0000
-2999999.00
1979
14 99999.00
0.0
0.0 0.0
- 1 *99999 .00
- 1 *99 99 9.00
0.9524
-1428571.00
1980
4 99999.81
0.0
382CC0.0C -913002.50
31002.69
13129.39
0.9070
119C3. 75
1981
0.0
0.0
390750.00 -601845.50
211095.50
202646.38
0.8638
175053.88
198?
0.0
0.0
399500.00 -6 03198•Oo
203688.06
:9 54 09.06
0.822 7
160763.94
1983
0.0
0.0
*08250.00 -604531.13
196291. 13
188172.25
0.7935
147430.31
198*
0.0
0.0
417CC0.00 -605874.19
188874.19
160935.50
0.7 *62
135017.38
19 85
0.0
0.0
482750.00 -274577.06
-209172.9*
-204723.69
0.7107
- 145493.94
1986
0.0
0.0
4915C0.00 -275919.94
-215560.06
-211960.63
0.6769
-143464.00
1987
0.0
0.0
500250.00 -277262.81
-222987.19
-219197.69
0.6446
-141297.56
1980
0.0
0.0
5C90C0.00 -278605.63
-230394.38
-226434,69
0.6139
-139012.1 J
1099
0.0
0.0
517750.00 -279948.50
-23780i.50
-2 33671.75
0.5 84 7
-136624.00
1990
0.0
0.0
600500.00 -316811.31
-283688.fo
-2 7 dot 5 . 50
0.5568
-155172.56
1991
0.0
0.0
609250.00 -318154.19
-291095.6 1
-2* 5>90i .50
0.5303
-151621.44
1992
0.0
0.0
6180CC.C0 -319497.06
-299502.0*
-29*139,50
0.5051
- 148056.69
1993
0.0
0.0
626750.00 -320839.94
-305910.06
-30 3 ? 76.56
0.4810
- 1444 £7,61
1©94
0.0
0.0
6355 CO.00 -3221 82.81
-313 317.19
-307613.*4
0.4581
-140922.69
1995
0.0
0.0
740680.00 -369812.06
-3708b7.9*
-364051.63
0.4363
-1*8836.25
1996
U.O
O.Q
749430.00 -37U54.88
-379275.13
-371288.69
0.4155
-154279.88
1997
0.0
0.0
7583 80.00 - 3 72 5 S3.75
-395786.25
-378627.75
0.3957
- 1498 37.69
1998
0.0
0.0
766930.00 -373R40.O3
-393089.38
-385762.63
0.3769
-145391.75
1999
0.0
0.0
7 756 8C.00 -375183.50
-400496.50
-392999.*3
0.3589
-141066.06
TCTALS
*9*9997.00
0.0 11379050.OC -8174817.00
-82 05012.03
-5993943.00
-------
328 Financial Planning
Table XII: Financing and Capital Expenditure Cash Flow Schedules Alternative #3
*******
SUMMARY
*******
TOTAL INVESTMENT (DOLLARS)
0.0
PRFStNT WCRTH OF FINANCING SCHEME
0.0
PRESENT WORTH OF CAPITAL EXPENDITURES
-6039633.00
NET PRESENT WORTH OF
PROPOSED PROJECT
-6039633.00
**********,************
CASH FLCW FCR FINANCING
***********************
YEAR PRINCIPLE
INTEREST
NE T
CASH 01
SC CUNT
DISCOUNTED
FLOW FACTOR
CASH FLOW
**** *********
********
******** ********
**********
1978 0.0
0.0
0. 0
1.0500
0.0
TOTALS 0.0
0.0
0.0
**********************************
CASH FLCW FOR CAPITAL EXPENDITURES
**********************************
YEAP INVESTMENT
REVENUE
OPERATING
TAX
GROSS CASH
ADJUSTED CASH
0 I SCOUNT
DISCOUNTED
EXPENSES
PA I 0
FLOW
FLOW
FACTOR
CASH FLOW
**** **********
*******
*********
****
**********
****** *******
********
**********
1970 0.0
0.0
0.0
0.0
0.0
0.0
1.0000
0.0
197% 0.0
0.0
0.0
0.0
0.0
0.0
0.9524
0.0
I960 0.0
0.0
710000.00
-340799.94
-369200.0b
-362260.56
0.9070
-328581.44
1981 0.0
G.O
71OOC0.CO
-34C7S9.94
-369200.06
-362260.56
0.8638
- 312934.88
1982 0.0
0.0
7lOOCO.OO
-340799.94
-369200.06
-362260.56
0.8227
-298033.44
1983 0.0
0.0
7100 CO.00
- 34 C7 9°.94
-369200.06
-362260.56
0.7835
-283841.56
1984 0.0
0*0
710000.00
-3*0799.94
-369 200.Ofc
-362260.56
0.7462
-270325.44
1985 0.0
0.0
511OC0.OO
-437279.94
-473720.06
-464816.00
0.7107
- 330337.56
1986 0.0
0.0
91lOCO.OO
-437279.94
-473720.06
-464816.00
0.6768
-314607.38
1987 0.0
0.0
9110C0.00
-437279.94
-473720.06
-464816.00
0.6446
-299626.25
198* 0.0
0.0
911000.00
-437279.94
-473 720.06
-464816.00
0.6139
-285358.56
1989 0.0
0.0
9110C0.00
-437279.94
-473720.06
-464816.00
0.5847
-271770.25
19Q0 0.0
0.0
11723 CO.00
-562703.94
-609596.0ft
-598137.38
0.5568
-333067.88
1991 0.0
0.0
11723 CO.00
-5627C3.94
-609596.06
-598137.38
0.5303
- 3172 C7.69
1992 0.0
0.0
11723CO.OO
-562703.94
-609596.06
-598137.38
0.5051
-302102.75
1993 0.0
0.0
11723CO.OO
-5627C3.94
-609596.06
-598137.38
0.4810
-287717.06
1994 0.0
0.0
11723 CO.00
-562703.94
-609596.06
-59 8137.38
0.4561
-274016.44
1995 0.0
0.0
1511990.00
-725755.13
-786234.88
-771456.75
0.4363
-336587.69
1996 0.0
0.0
1511990.00
-725755.13
-786 234.86
-771456.75
0.4155
-320559.94
1997 0.0
0.0
1511990.00
-725755.13
-786234.80
-771456.75
0.3957
-305295.38
1998 0.0
0.0
1511990.00
-725755.13
-786234.88
-771456.75
0.3769
-290757.69
1999 0.0
0.0
1511990.00
-725755.13
-786234.88
-771456.75
0.3589
-276912.25
TOTALS 0.0
0.0 21526432.00-
10332683.00 -
11193750.00
-6039633.00
Table XIII: Summary of Net Present Worth Values Table XV: Summary of Peak Cash Outflow Values
Alternative *1
Alternative #2
Alternative "3
NPW of Financing
Cash Flows
-$ 6,433,356
-$ 4,288,900
50
NPW of Capital Expendi-
ture Cash Plows
-$ 6,053,7S7
-$ 5,993,952
-$ 6,039,633
Total NPW
-$12,487,113
-$10,282,852
-$ 6,039,633
Alternative
Peak Cash Outflow
Year
1
-$ 4,841.100
1978
2
-$ 3,227,400
1978
3
-$ 786,235
199S-1999
Table XIV: Summary of Short-Term Profit Impairment Values
Annual Net Cash Flows
Alternative #1
Alternative #2
Alternative *3
1978
-$
4,841,100
-$
3,227,400
$0
1979
-$
K>
Jk
o
o
-$
1,627,400
0
1980
36,365
-$
96,397
-$
369,200
1981
307,478
~$
83,696
-$
369,200
1982
-$
77,658
-$
173,712
-$
369,200
Totals
-$
7,016,015
-$
5,041,213
-$
1.107,600
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Financial Planning
329
ALTERNATIVE NO I
¦ ALTERNATIVE NO 2
-+-
H
1978 1980 1982 1984 1986
Figure 5: Sample Problem Annual Net Cash Flows
1988
1990
1992
1994
1996
1998
2000
YEAR
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