United States
Environmental
Protection Agency
Office of
Research and
Development
EPA-600/9-78-022
October 1978 <
Energy, Minerals and Industry
vvEPA Decision Series
energy/
ent
environ
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the energy/environment
R&D decision series
This volume is part of the Energy/Environment R&D Decision
Series. The series presents the key issues and findings of the Federal
Interagency Energy/Environment Research and Development Program in
a format conducive to efficient information transfer. Planned and
coordinated by the Environmental Protection Agency (EPA), research
projects supported by the program range from the analysis of health and
environmental effects of energy systems to the development of
environmental control technologies.
If you have any comments or questions, please write to Series
Editor Richard Laska, Technical Information Office, RD-674, U.S. EPA,
Washington, D.C. 20460 or call (202) 426-9455. This document is
available from either the Series Editor or the National Technical
Information Service, Springfield, Virginia 22161. Mention of trade names
or commercial products herein does not constitute EPA endorsement or
recommendation for use.
Symposium and Report Credits:
EPA/OEMI Symposium
Committee:
Symposium Coordinator/
Associate Editor:
Assistant Symposium
Coordinators/Associate
Editors:
Symposium Support:
Mark Schaefer, Chairman
Clint Hall
Steven Plotkin
Frank Princiotta
Kathleen Dixon
Karen Sykes
Susan Fields
Anne Abrahamson
Hartley O. Holte
Peter Mavraganis
Pat Selk
Gary Sitek
Robert Spewak
Editor:
Elinor Jane Voris
Associate Editors: Elizabeth Caldwell
Paula Downey
Art and Design: Jack Ballestero
Graphic Support:
Photography:
Howard Berry, Sr.
Elizabeth McKinney
Thomas Jones
Juan Medrano
Harry Harrison
Jack Meyer
Lawrence Dixon
and selected photo-
graphs from the EPA
Documerica Program
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energy/
environment
Third National Conference
on the Interagency R&D Program
June 1 and 2, 1978
Shoreham Americana Hotel
Washington, D.C.
SPONSORED BY:
The Office of Energy, Minerals and Industry
Within the Environmental Protection Agency's
Office of Research and Development
U 8. Enviror.men*til Protection Ajency
[•'-•.r.',-r ^ h.lcimalion Resource
Ztt C:>c-s'.:.ui Street
PfiiSadciphia, PA
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TOPICS
overview
CHAPTER 1
29
health effects
CHAPTER 2
75
transport processes
and ecological effects
CHAPTER 3
165
mining methods
and reclamation
CHAPTER 4
221 control technology
CHAPTER 5
353
integrated technology
assessment
CHAPTER 6
383
participants' index
386
federal agency
acronyms
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chapter 1
overview
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Chapter 1 Overview
CHAPTER CONTENTS
overview
FOREWORD
Steven R. Reznek, Ph.D., US EPA 5
OPENING REMARKS
Stephen J. Gage, Ph.D., US EPA 7
KEYNOTE ADDRESS
The Honorable Frank Press
Office of Science and Technology Policy 9
LUNCHEON ADDRESS
The Honorable Charles Warren
Council on Environmental Quality 19
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OVERVIEW
FOREWORD
Steven R. Reznek, Ph.D.
Office of Energy, Minerals and Industry
U.S. Environmental Protection Agency
The Interagency Energy/Environment R&D Program unites more than a dozen
Federal agencies to ensure that unresolved environmental issues are not a barrier to
timely and safe development of our domestic energy resources. To this end, the
Office of Energy, Minerals and Industry within EPA's Office of Research and
Development has, as coordinator, invested approximately $100 million a year in the
Program since its inception in fiscal year 1975.
Substantial progress has been made toward achieving our goals. Selected
achievements were reviewed at the Third National Conference on the Interagency
Energy/Environment R&D Program, convened in Washington, D.C., on June 1 and 2,
1978. These Proceedings are a result of that Conference.
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Energy/Environment III provides an update of Interagency researc effects^
ticular areas, including health effects, transport processes and ecologica .'
mining methods and reclamation, control technology, and integrated e
assessment. This report consists of the addresses, papers, and panel discussion
Conference.
This report and conference, along with publications in our Energy/ nviro
Decision Series, such as the Who's Who in the Interagency Program and the hnergy/
Environment Fact Book, highlight one of the most important roles of our
program-to link the people who need information to the people who have it. Most
of us are becoming increasingly aware of a major change that is taking place within
our economic and industrial institutions. Recent shortages and price hikes nave
brought home the fact that we cannot sustain a business-as-usual approach to our
destiny.
We feel the need to act-but in what direction? More and more, our attempts
to adjust one sector of our society run headlong into conflicting goals in other
sectors. Environmental goals are being questioned on economic and energy-related
grounds. Energy development efforts are challenged on environmental issues.
Adjustments in the economy to discourage the waste of energy are confronted with
arguments of equity and efforts at reducing unemployment.
It seems that we, as individuals and citizens within a democracy, have three
valid responses to these conflicts. First, we can turn off—turn away from the
discussion and occupy ourselves with our own concerns. Second, we can
energetically enter the debate on the side of our own narrow self-interest. Third, we
can seek to understand the issues involved and participate in the building of a new
national consensus.
It is to this third response that our efforts here are dedicated. We, as
scientists, engineers, and research managers, see it as our responsibility to provide
the options. Whatever path the nation chooses, we will strive to supply both the
knowledge and the technologies necessary to ensure that our energy supplies will be
adequate and our environment will be healthy. In short, we will do our best to
provide the ship of state with power, but there must be a wise hand on the helm.
We wish to express our thanks to all who, through their effort and
participation, contributed to the success of this Third Conference and to the
publication of these Proceedings. We are justifiably proud of the Program's
achievements. We are, however, equally cognizant that there is much work yet to be
done to ensure that our need to develop new and different energy sources and
resources is compatible with concern for the integrity of our natural systems.
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OPENING REMARKS
Stephen J. Gage, Ph.D.
Office of Research and Development
U.S. Environmental Protection Agency
ARAB OIL EMBARGO
ALTERNATIVE RESOURCES
The Interagency Energy R&D Program was created after the Arab oil embargo
in the winter of 1974. Before the embargo, most Americans felt that energy supply
was a public service that was available to meet nearly all possible demands at
relatively low prices. After the embargo we became aware of the fact that oil and
other fossil fuels are not available to meet our needs in whatever quantity we want.
Economics reared its ugly head. For the average American the big car honeymoon
was over, and consumers began looking for smaller cars that could save gasoline and
money. That trend may have unfortunately been reversed in the last few years. The
speakers at the first National Conference in 1976 reminded us that the Energy Crisis
meant that our energy supply as a public service, almost as a free good, was ended.
It is a commonly understood axiom of our economic system that as demand
increases and supply declines the price of a resource rises. Concomitant with this
price rise is a leveling off of demand, supposedly, and a search for new resources.
Mr. John O'Leary, who was our speaker at last year's Conference and is now the
Under Secretary for Energy, reminded us that alternative resources, such as solar
energy, nuclear energy and fossil fuels, are available to meet our energy needs, but
at substantially higher prices than we have been paying for oil and natural gas.
Nuclear power, coal, oil shale, and other technologies cost more than either oil or
natural gas and have the potential for greater environmental consequences.
Therefore, as Mr. O'Leary pointed out, our nation faces rising costs for the
replacement of energy supplies and also to protect environmental quality while these
alternative sources are being used.
Before the energy embargo, pollution control and environmental protection
were viewed as programs designed to help solve existing problems. By and large they
were designed for the use of well-established control technologies on existing waste
discharges.
After the energy embargo another view of environmental protection emerged
that would steer the future course of our technological society. That future will see
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THE ENERGY CRISIS
INTERAGEIMCY PROGRAM
limited supplies of higher grade ores and natural resources consumed. Technological
innovation will allow the use of lowered grade ores and different resources or the
use of the traditional resources in new and more efficient ways. An era of the
world's history is rapidly coming to a close. We no longer believe that natural
resources will be rewarded by a growing economy and that discharge cleanup will
protect the environment. Although we have all witnessed some of the near-term
economic, political, and environmental implications with the closing of the
petroleum age, none of us can forecast accurately what the future has in store.
The energy crisis could mean a protracted and gradual worsening economic
recession, lack of opportunity for young people, and decreasing social mobility. It
could mean a rapidly degrading environment, an exhaustion of our supplies of clean
water, clean air, and productive land. On the other hand, the energy crisis may only
mean that the cost of energy will rise to a point where widely available and more
economically acceptable sources will be used to meet society's economic and social
need. The exact course of our future cannot be predicted. The federal government is
spending immense resources on research, development of demonstration projects to
help shape that future.
The Interagency Program is one of the major efforts to create the information
and knowledge necessary for responsible deci;ionmaking not only by the federal
establishment but by the individual American. Hopefully, our program has helped to
clarify and define some of the environmental energy problems and to make that
decisionmaking process a little less difficult. I say hopefully because I recently read
a story about a consumer who was concerned about the use of nuclear power as an
alternative energy source. At a stockholders' meeting of a major west coast utility,
the shareholder told the company president that his neighbor was afraid that, if
nuclear power came into widespread use, radiation might come leaking out of his
wall socket. The utility company president, who was obviously a very bright man,
said not to worry, that the neighbor really should be more concerned about
important things—for instance, the utility was currently experimenting with cow
manure as an alternative energy source.
Seriously, communication is what this Conference is all about, and I am
looking forward to hearing about and discussing the major achievements of this past
year.
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COORDINATING THE ENERGY/ENVIRONMENT RESPONSE
The Honorable Frank Press
Office of Science and Technology Policy
CENTRAL CHALLENGE
FOR AMERICANS
GROWING DEPENDENCE
ON TECHNOLOGY
ENERGY-INTENSIVE
LIFE-STYLE
From a cursory study of our recent history, it appears that each generation of
Americans is tested and tempered by a central challenge. In this century, for
example, we had the First World War, the Depression, the Second World War, and
the social and political revolution of the 1960's. The more we study the facts and
the more we understand about the underpinnings of our society and way of life, the
more clearly we see that the challenge of the rest of this century, barring some
unforeseen calamity, will be to maintain our quality of life, in the face of global
economic pressures and resource limitations. And by far the most important of our
limited resources will be usable energy.
Science and technology have given us ever more powerful energy sources, and
also a growing dependence on them. Individual Americans now have far more power
to do work than could have been mustered by many of the most renowned rulers
of the past, but in terms of the technologies that support our lives today, this
energy use is all but essential. For example, if we live or work in a high-rise
building, we are highly dependent on electricity to circulate the air we breathe and
to operate the elevators we ride. Most of us live beyond practical walking distance
to a market, and must have an automobile to get our food. And the very food we
eat is the product of an energy-intensive agricultural technology and was probably
frozen, pasteurized, and/or transported a thousand miles or more to reach our
tables.
Our entire society and economic infrastructure would face collapse if our
energy supplies were suddenly cut short. In our bargain with technology to obtain a
higher standard of living, we have become almost totally dependent upon that
technology for the continued vitality of our culture. I am not speaking here in
terms of the individual who chooses to go off into the wilderness, live off the land,
and lead a life that is nearly self-sufficient in terms of energy. This may be possible
for a handful of adventuresome people, but very few of us choose to commit
ourselves to that option. Most of us are committed to an energy-in tensive, modern
life-style and all of its accoutrements.
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BURDEN ON TECHNICAL
COMMUNITY
BREAKTHROUGHS-
IMPOSSIBLE TO SCHEDULE
RESEARCH PRIORITIES
ENERGY PATH
Since science and technology brought us this life-style, people assume, quite
understandably, that science and technology will continue to maintain and improve
that life-style. This puts a tremendous burden on the scientific and technical
community to make good on the expectations of our fellow citizens. Fortunately, it
is a burden that, up to now, we have been able to meet with both resources and
imagination. I assume that almost everyone in this room is today playing some role
in this process of energy supply and its related problems.
There are two parts to this effort, without either one of which we would be
hard-pressed to show any progress. The first part involves science and
technology—science to provide us with sufficient understanding of the complex
problems involved in accelerating domestic energy development, and technology to
translate that understanding into reality. The second, and equally important, part of
the solution is not technical at all—it is institutional. Above and beyond our
scientific endeavors, there are social, economic, and political forces that must be
factored into the equation. It is these forces that provide us with the funds to do
our research and development, and it is these forces that determine whether or not
our research results and technologies will be sufficiently relevant to the problems at
hand.
I am not saying that if we technologists were left alone, we would surely
come up with a solution to the energy crisis. Far from it. Unfortunately, the
continued faith that Americans have in science and technology is often accompanied
by a tendency to look upon scientists and technologists as the unfailing solvers of
all problems. We scientists know that this is hardly the case. We suffer our share of
failures—many of them—and we have all learned the hard way that major
breakthroughs are impossible to schedule. Sometimes it appears that breakthroughs
are harder than ever to achieve now—just as more problems seem difficult to resolve
fully these days. Residual problems or related impacts are always cropping up. There
seems to be a lot of truth in a cartoon that appeared in the Wall Street Journal
recently. It showed one man at a bar commenting to another, "Remember the good
old days, when problems had solutions?"
In view of this, I believe it is as much our responsibility to inform the
decisionmaking community of what we cannot do as it is to tell them what we can
do. We should also be able to point out where alternatives to technical solutions
may be available. And it is just as much our role, as technologists, to point out to
the decisionmaking community where economic, social, or political situations offer
significant opportunities for progress as it is the role of the socioeconomic and
political communities to establish our overall research priorities.
In the light of these dual responsibilities, the current debate over which path
our Nation should follow to find the energy it needs becomes a little more complex
and a little less obvious. The most simplified version of the debate pits the "hard"
energy suppliers against the "soft" energy conservers—the coal and nuclear power
supporters against the conservation and renewable-resources advocates. The labels we
choose for these alternative paths are not important. What is important is that there
is a tendency to polarize our energy/environment philosophies. One side advocates
expanded use of our existing fossil fuel and nuclear resources; they argue that we
can rely on our existing oil, gas, coal, and uranium reserves for as many years as it
takes to solve the economic, technological, and social problems associated with
nuclear and advanced power systems. Others see a future in which we rely solely on
our renewable resources—solar, water, and geothermal. These latter energy sources
have great appeal, because they appear to be relatively less polluting than our coal
and nuclear resources.
I see problems with either path, if chosen at the expense of the other. Where
would we be, for example, in the year 2000 if our Nation had been traveling the
coal-nuclear path exclusively for more than 20 years? What would be our alternative
if we had not yet solved the plutonium or radioactive waste problems, or had
discovered serious health or environmental hazards from electricity transmission grids,
or had determined that CO2 was causing our atmospheric temperature to rise? It
would already be too late to say we should have placed greater emphasis on
geothermal research and development (R&D), or the Federal Government should
11
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CONSERVATION PATH
have accelerated its support of the construction of solar collecting units, or shou d
have encouraged more intensive conservation efforts. By the year 2000, our best
efforts at shifting priorities would be "too little, too late."
Or let's consider the other direction-the conservation renewable-resources path.
If, for the next two decades, we were to concentrate entirely on solar technologies,
where would we be if our conservation hopes proved somewhat idealistic and highly
impractical? We would have spent tremendous amounts of money and, even more
important, precious and irretrievable time on solar R&D at the expense of other
promising technologies. We would not have the technologies to burn coal cleanly
and efficiently, and our nuclear problems would remain unsolved. Again, we would
have painted ourselves into a corner and lost the energy gamble—a precarious
position for a highly industrialized nation such as ours.
It is for this reason that we must avoid taking polarized viewpoints toward our
energy future. Compromise is necessary to ensure that both short- and long-term
energy requirements are met in such a way that our Nation's economic growth is
not inhibited by an energy shortage due to poor technological planning.
AIR QUALITY STANDARDS
EMPHASIS ON SAFETY
AND WASTE MANAGEMENT
President Carter made clear, in the National Energy Plan, his intention to take
a balanced approach towards development. This Adminstration is committed to
increasing our use of coal under stringent environmental controls while, at the same
time, reducing our dependence on foreign oil and gas reserves.
To ensure that air quality standards are no^ sacrificed as we convert to coal,
the Administration has supported and encouraged the R&D performed by the
Department of Energy, and other Federal agencies, and has given added emphasis to
the Interagency Energy/Environment Program. Initiated in late 1974, the interagency
program has invested more than $430 million to date, most of it to support
coal-related efforts. Direct burning of coal is required in the short- and mid-term,
until the more advanced technologies, such as fluidized-bed combustion and coal
gasification, can be commercialized. Flue gas desulfurization systems, or scrubbers,
are now in commercial use as a result of the quality research performed under the
interagency program, which is planned and coordinated by the Environmental
Protection Agency. The plans of the utility industry call for a large portion of
coal-fired power plants to be equipped with scrubbers within the next decade.
In the short- and mid-term, coal, conservation, and nuclear fission are our
most promising approaches to achieving a reliable energy supply. However, we
should keep in mind that we are only buying time until our solar, nuclear fusion,
and other renewable-resource technologies are sufficiently advanced to take over as
primary energy sources.
Federal solar R&D has greatly increased in the past 3 years, and I expect this
trend to continue. Just as Earth Day was the harbinger of the environmental era, so
Sun Day should mark the beginning of an age when we as a nation become
seriously committed to the development of practical efficient solar technologies. But
we must not confuse commitment with accomplishment. Our drive toward the
development of solar energy technologies must be tempered with realism concerning
the time it takes to make a major energy transition. In an energy-dependent society
such as ours, a severe energy shortage could be disastrous.
For this reason, along with solar energy development, the development of our
nuclear resources is essential. The necessity for nuclear-related environmental R&D is
also readily apparent. Plutonium's extreme toxicity, together with the fact that it
may be used to manufacture nuclear weapons, requires us to look very closely for
alternative nuclear technologies. In April of last year, the President made clear the
Administration's policy on this subject by presenting detailed plans to restrict the
use of plutonium as a fuel source. While we look for alternative nuclear fuel
cycles-those that will not involve the production of plutonium-the United States
will have to rely increasingly on light-water reactor technologies. The R&D
community will, therefore, have to place greater emphasis on solving the safety and
waste-management problems associated with this type of reactor.
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-Jjji
.
COMBINATION OF TECHNOLOGIES
In the long-term, it is difficult to say what technologies will emerge as the
most environmentally and economically practical. Whether it be nuclear fusion, solar,
advanced fossil fuel technologies, or, more probably, a combination of these, our
present balanced approach will provide us the time necessary to ensure thoughtful,
organized alternatives.
The problem is not simply one of technology or science. It is also one of
politics, institutions, economics, and social attitudes. Let me illustrate this point
with some examples. The United States is committed to the automobile as its major
form of transporting people. Our highway system, parking facilities, fuel supply
network, urban and suburban population patterns, and distribution systems represent
a capital investment of half a trillion dollars or more. And it is an investment which
gives us a significant advantage over most of the other nations of the world in terms
of social mobility and opportunity for personal freedom.
But we pay a high price for this advantage. The automobile is responsible for
a large portion of our nearly $50 billion per year foreign oil debt. It is, for all
practical purposes, the key factor in enforcing our continued dependence upon
foreign oil. And yet, if anyone were to propose that all automobiles be required to
achieve twice the fuel efficiency that they do today, there would be an uproar.
Here the problem has little to do with technology, and even less to do with basic
science. It has to do with a firmly established set of institutional interests and the
economic and social patterns that have been generated over a period of years.
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COGENERATIOIM
Another case where institutional barriers outweigh technical ones is in the area
of cogeneration—the simultaneous production of industrial process steam and
electricity. Until about 25 to 30 years ago, a great deal of electricity was produced
in this country by factories and industries. In fact, at one time, congeneration
facilities were providing 15 percent of our electricity. The availability of relatively
inexpensive oil in the post-World War II period discouraged the burning of coal, and
various institutional problems have, over the years, acted to discourage the use of
this potentially important source of electricity. At the present time, cogeneration is
providing only 4 percent of U.S. electricity.
Partly because of State and Federal Government regulation, utilities make little
or no profit from the purchase of electricity from an industrial firm. There is also
the problem of rate incentives. Utility rate schedules have, for many years, been
structured in such a way as to discourage a potential industrial user from generating
power. Obviously, if there is no financial incentive for a firm to generate its own
electricity, the economic feasibility of cogeneration facilities is in question.
To promote cogeneration, President Carter has proposed exempting industries
using cogeneration from State and Federal public utility regulation. Additional
proposed incentives are intended to ensure that industries which generate electricity
receive reasonable rates from utilities. I am confident that, as the American people
become aware of the advantages of cogeneration and are informed of the barriers
blocking its implementation, they will work with us to convince the appropriate
governmental organizations of the necessity for change.
PROBLEMS AT PERSONAL
LEVEL
In addition to these broad-scale institutional problems, there are others at a
more human and personal level. To install and maintain solar-powered heating
systems, for example, requires additional training and experience for the local
plumber and contractor. Solar water heaters cannot be installed with an imprecise
attitude of "if it doesn't leak, it's just fine." The proper materials must be selected
and proper techniques used to ensure efficacy, maintainability, and durability over
an extremely long-30 to 50 years or more-system life. We are at a formative point
in the development of solar-powered systems. Technical specifications and perfor-
mance criteria must be set quickly, or the public will soon grow wary of inferior
solar-powered systems. On the other hand, room must be left for initiative and
inventiveness so that future progress is not hindered by oppressive technical
specifications or excessive and slow bureaucratic processes.
PROBLEMS OF COMMUNICATION
Another major institutional barrier to the full realization of scientific creativity
is the legalistic contract mechanism. For example, to obtain any significant level of
contract support for a new idea or technology in today's environment takes at least
one year, if not more. And it requires such an explicit description of what is to be
accomplished—and proof that it can be accomplished—that it often appears necessary
to do most of the research before even submitting the contract proposal. These
delays and excessively demanding scopes of work are, it appears, intended to ensure
that Federal research money is not wasted on experiments or technologies that may
fail.
This whole approach contradicts the entire scientific research method. If an
experiment fails to produce a commercially practical product, that does not mean
that it has failed to provide the key information necessary to produce that product
at some future time. We often learn more from our failures than from our successes.
Unfortunately, the Federal contracting procedure allows too little flexibility to deal
with funding high-risk research. And this lack of flexibility is not saving Federal
money-it is wasting it by allowing promising ideas to go untested. Contracting
procedures at the Federal level should rely more heavily upon the judgment of the
scientific or technical project officer as to what constitutes adequate justification for
a contract The project officer is paid to exercise that judgment, but all too often
the exercise becomes an interminable and frustrating process of wordsmithing.
It seems to me that a great many of our institutional barriers-and some of
our technological ones-are actually problems of communication. I cannot count the
number of times I have heard my peers complain about the poorly informed
14
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CORNERSTONE TO R&D
PROGRAM
technical decisions being made at the policy levels. However, the responsibility for
keeping the policy levels well-informed can be no other than ours. And we can do
better.
There are two key communications links which must be formed in order to
make our efforts both relevant and more efficient. The first link is within the
research community itself; the second is between that community and the policy
level decisionmakers and interested public.
Communicating within the research community is the cornerstone of a
coordinated research program. In such a broad area as the health and environmental
effects of energy systems, the problem of coordination is a real challenge. Through
reports, seminars, and conferences such as this, the interagency program brings
together the key actors in various aspects of energy/environment research and
development. Such direct contact is an effective way to coordinate the Federal
research effort and to avoid unnecessary duplication of, or misdirection of, research.
No matter how often we reorganize, there will always remain many important
topical areas which cut across organizational and agency lines.
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INDUSTRIAL INNOVATION
GOVERNMENT'S ROLE
But if coordinating research and development within government is important,
perhaps of even greater importance is the coordination of R&D between government
and industry—between the federally and privately funded sectors. The roles of
Federal and private R&D communities are, in many respects, naturally defined.
Industry is somewhat reluctant to engage in major exploratory basic research because
of the length of time it takes for the payback-sometimes 25 years. Additionally,
basic research is difficult to keep secret, especially from one's competitors. Hence,
some sectors of industry see little financial incentive in basic research. On the other
hand, the private sector will engage in a high-technology research area where the
return on investment is more secure.
These are all matters that are going to be examined in some depth, with a
view toward creating new policies to deal with them, in a new interagency study of
industrial innovation. The President announced this major study a few weeks ago
and is looking forward to the policy options it will bring him.
The principal motivation for the study is the idea that industrial innovation is
central to the economic well-being of the country. It is seen as providing a basis for
economic growth and as intimately related to such important concerns as
productivity, inflation, unemployment, and the competitiveness of U.S. products in
both domestic and world markets. There are a number of observations that
underscore Federal concern over industrial innovation. Among them are industry's
underinvestment in innovation; increased private-sector R&D on low-risk, short-term
projects directed at incremental product change, rather than longer-term research
that could lead to new products and processes; declining international competitive-
ness; lagging productivity; and difficulties on the part of small, high-technology firms
in obtaining venture capital. There is also the matter of industry's recent diversion
in innovation, from a focus on new products to meeting other goals, such as the
requirements of environmental quality or consumer safety. Efforts must go into
so-called defensive research, rather than into exploratory work that might break
some totally new ground.
In the past year I have met with a number of vice presidents for industrial
R&D to discuss these matters. A common feeling running through these meetings
was that excessive Federal regulation hampered innovation, creating a climate of
uncertainty that inhibited exploratory R&D. Industry was forced to spend a
substantial portion of its R&D money in so-called defensive activities in order to
comply with the many overly strict and ever-changing environmental and consumer
safety regulations.
They were especially critical of the inflexible and zero-risk criteria built into
some of the regulations. This type of regulation, they felt, drove exploratory
research and product development overseas. I rarely heard any arguments in favor of
the regulations, though such arguments do exist.
Before the new rules, many products were not adequately tested and evaluated
for environmental and consumer safety before marketing. Therefore much of the
regulation was demanded by the public. New evidence was continually being
developed, and scientific uncertainty or inconclusiveness prompted conservatism in
considering risks.
At the time when most of the rules were promulgated, the public consensus
was in favor of conservatism. It is the Government's role and responsibility to
protect the public and to consider the social costs, the broad effects on the
environment, and the public health, which were once external to the business
community. Most of the regulations were therefore based on legislation following
extensive investigation and hearings.
One way we can advance our R&D and the process of innovation is to
improve information transfer between the technical community and the decision-
makers and the public. It is the responsibility of the technical community to ensure
that the policymakers and concerned citizens are provided with enough information
to be able to make intelligent decisions that will then guide our research efforts. It
is also our responsibility to provide that information in a form which can be easily
16
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BUILDING A CONSENSUS
understood by the intended audience. It is not enough simply to produce massive
volumes of technical data and scientific papers—this we do for our peers and not for
the decisionmakers. We must also endeavor to translate our findings into a form
which can be used to directly influence the decisionmaking process.
As we communicate, as we coordinate our efforts, we build a consensus. A
consensus is nothing more than a common judgment arrived at by the majority of a
concerned group. By helping to build a consensus as to what path we should take
to assure a future with adequate energy, we clarify and redefine the problems facing
us. We should realize that effective decisionmaking requires a definition of the
problem and then a solution—not vice versa. Interagency programs are, then, part of
an important effort to clarify and define problems and to offer viable solutions
through a communication process. It is this process which builds the consensus, and
upon this consensus depends our ability to act.
You are here to help in achieving that consensus and in improving the
coordination of our energy and environmental programs. In those most important
tasks, I wish you the very best of success.
17
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TO HELL WITH IT:
NAVIGATING A SEA OF ENVIRONMENTAL HAZARDS
The Honorable Charles Warren
Council on Environmental Quality
HAMBURGERS CARCINOGENIC?
IS NOTHING SAFE?
Some years ago, the New Yorker published a cartoon that depicted a woman
reporting the disappearance of her husband to the Bureau of Missing Persons. A
police officer at the desk was taking down his description. "He's 43 years old," the
bereaved wife said; "he's about 5 feet, 5 inches tall, has prematurely gray hair, sort
of a nondescript face, and a receding chin." At that point the woman paused,
thought about the description she had just given, and then said to the police officer,
"Oh, to hell with it."
I was reminded of this cartoon a couple of weeks ago when Dr. Barry
Commoner revealed that the humble hamburger, as it is usually fried,, might prove
carcinogenic. Over the years, we have had indications that cyclamates, saccharine,
red dye No. 2, and the aerosol used to propel deodorants might all harm our health
or our biosphere. More recently, Americans who are into consciousness-expanding
techniques have become alarmed about the use of the herbicide paraquat for
spraying Mexican marijuana. If any frosting were needed on this environmental cake,
we might consider Dr. Commoner's consoling observation that hamburgers are all
right if you fix them in a microwave oven. From other quarters, however, come
allegations that prolonged exposure to radiation from microwave ovens can harm the
eyes.
Considering the multiplicity of environmental problems today, many an
American might conclude that nothing is safe. If melanoma cancer from reduction
of the ozone shield by fluorocarbons doesn't get you, cancer of the stomach from a
Big Mac will. If you decide neither to smell nice nor to eat well, but to go to bed
early and light up a joint, your pajamas may catch fire while you twist with
intestinal agonies caused by an herbicide designed to eradicate a Mexican plant.
After reviewing the environmental hazards past and present, I am frankly surprised
that our people have not decided that environmental protection is more trouble than
it's worth, or concluded, with the lady in the New Yorker, "To hell with it."
But they have not. On the contrary, judging by the opinion polls, public
support for environmental protection is not merely holding firm but is actually
19
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HARD CHOICES VS.
WISH LISTS
HONEYMOON WITH THE
PUBLIC
RALL STUDY
growing. I was astonished by a Lou Harris poll of last March which indicated that,
by a majority of 71 percent to 18 percent, American people would rather live in
an environment that is clean, rather than an area with a lot of jobs."
That kind of support is heartening to those of us who have professional
obligations as well as personal commitment to environmental protection. Yet I
question the true strength of that public support. It is sincere, but it has not yet
been severely tested in a real-life situation that forces one to make hard choices. It
is one thing, for example, to favor a clean environment over job-creation when you
already have a job. It is quite another to support such a choice when you don't
have a job, and when a proposed energy project would create one for you. It is one
thing to be skeptical of further nuclear development when your house is heated; it
is quite another to oppose such development when the oil runs out. Lacking the
necessity for making a genuine choice whose consequences each individual,
personally and directly, will have to bear, public opinion polls tend to be "wish
lists." As Mr. Harris himself concluded after summarizing opinion on
environment-energy issues, "The people . . . believe deeply in the system and its
capacity to perform miracles and to do the impossible."
In sum, despite the arguments that rage over specific environmental policies,
we have enjoyed a kind of honeymoon with the public over the last decade. We had
better make the best use of it, because the heady bliss of these early days will not
continue indefinitely. Only when the hard choices start—when serious conflicts
arise—can one decide whether the honeymoon will deepen into marriage or wither
toward divorce.
In no other area of environment-related policy is there a greater possibility for
conflict than there is in the energy field. Nor does any other aspect of
environmental protection affect so many people. It is these characteristics that give
such urgency to our work, for, by the time the honeymoon ends, we must not only
be able to meet our energy needs; we must be able to do so safely and in an
environmentally acceptable manner. Prudent public policy demands we do no less.
Two examples of the need for the environmentally prudent course in energy
policy development have recently emerged from specialized research to become
interesting subjects for conversation among informed laymen—acid rain and carbon
dioxide buildup. These, of course, provide much more than interesting conversation.
Both have the potential for massive damage. Both point up, moreover, the irritating
unknowns that make environmental protection such a frustrating profession.
One of the basic tenets of President Carter's National Energy Plan is a greater
dependence on the use of coal—through direct combustion in boilers, for the
immediate future, and through liquefaction and gasification in the more distant
future. Neither of these approaches is free of damaging side effects. Consequently,
President Carter directed that a study be undertaken by a committee of nationally
recognized experts to assess the potential impacts of increased coal combustion upon
public health and the environment generally. The urgency of charting a sane course
for national energy development required an intense and concise appraisal of a very
complex issue. The study, completed in January of this year, is called the Rail
Study, after the chairman of the study group, Dr. David Rail, Director of HEW's
National Institute of Environmental Health Sciences. As several members of that
committee are on the agenda for this conference, I will treat the study only briefly.
The charter for the Rail Study focused on the environmental impacts of
increased coal combustion. Soon after beginning work, however, the committee
found several problems that would require attention even if there were no increase
at all in the combustion of coal and other fossil fuels. Two of those problems are
acid rain and carbon dioxide buildup.
Although a few U.S. scientists have conducted research on acid rain,
Scandinavian scientists were first to gain widespread attention for the problem. To
avoid the local impacts of sulfur and nitric oxides, past and present practice in
Europe has been to diffuse such pollution by discharging it from tall stacks. This
worked fine for the locals, but prevailing weather patterns carried it northward, into
20
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PH UNITS
EXPANDING U.S. ACID
RAIN BELT
LONG-TERM THREAT
Norway and Sweden, and deposited it in quite different form. Through combination
with moisture, the SOX and NOX fell back to earth as dilute acids.
Acidity can be expressed in pH units, on a scale from 0 to 14. A pH of 7 or
below is acidic. Normal rainfall is slightly acidic, owing to normal background
constituents such as carbon dioxide; it has a pH of 5.7. In parts of southern
Norway and Sweden, however, the annual average acidity of rainfall has fallen below
4.3. That may not sound like a particularly drastic change; however, owing to the
peculiar mathematics of the pH calculation, such rainfall is 25 times as acidic1 as
normal.
Some soils can buffer this acidity, but Scandinavian soils are deficient in this
respect, and runoff following acid rains has been heightening the acidity of lakes
and streams. About 5,000 lakes in Sweden are estimated to have been acidified
below a pH of 5.0, and fish populations in some lakes have been exterminated.
Norwegian scientists estimate that 20 percent of the fish in their southern bodies of
water have been similarly affected, and the annual loss in the catch of Scandinavian
salmon alone is estimated at $10 million.
We have observed the same trend in the acidity of rainfall in the northeastern
United States. In some places, such as the Philadelphia-Wilmington area, the current
average pH of rainfall is as low as 4.0, and values in the range of 3.6 to 2.1 have
been observed in single storms. This is 100 to 4,000 times—repeat, 4,000
times—more acidic than normal. Further, the "acid rain belt" in the U.S. has greatly
expanded. In the mid-1950's, the pH of rainfall over roughly half of the area east
of the Mississippi River averaged below 5.d; now such an acidity level is found in
rain over the entire eastern United States.
The systems most strongly affected by acid rains tend to be high-altitude
forests, streams, and lakes-which suggests a serious long-term threat to many national
parks and forests. Of the mountain lakes in the Adirondacks located above the
600-meter line, 50 percent now have a pH of less than 5.0; and 90 percent of those
are totally devoid of fish. By comparison, only 4 percent of the lakes were in this
condition in the 1930's.
21
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CO2 ADVERSE EFFECTS
The chain of causality here is not precisely defined. I recently saw a report
which claimed that the toxic effect on fish resulted not from the acid rain directly,
but from increased amounts of aluminum in soil runoff triggered by the rains. In
any case, acid rains are implicated, and the effects on fish have been demonstrated.
Other adverse effects, according to studies from Europe, Canada, the Soviet Union,
and the U.S., may include:
• Decreases in agricultural and forest yields
• Depletion of nutrients from soils or aquatic systems
• Inactivation of important microorganisms
• Corrosion or deterioration of materials.
Because evidence on this issue is so incomplete, it is premature to assume that
a crash control effort is needed. On the other hand, it is certainly not premature to
plan a comprehensive assessment of the acid rain problem. Such an assessment
would determine the relationship between emissions and levels of acid rain through
monitoring and modeling, determine current effects through field investigations, and
determine the potential future effects through laboratory and controlled field
studies. With the results of that assessment in hand, we could understand the
dimensions of the problem—whether, for example, the effects of acid rain are
reversible or not, determine how much of it the environment can tolerate, and then
develop control strategies for the excess.
CO2 BUILDUP
The second energy-related problem rjas received vastly more publicity than acid
rains, undoubtedly because of its purported doomsday consequences. In fact, a
popular novel of the "disaster" category has already been written about C02
buildup possibly leading to the "greenhouse effect." Carbon dioxide levels in the
atmosphere have been on the rise at least since the start of the Industrial
Revolution and have increased by 5 percent in the last 20 years. C02 in the
atmosphere helps to control the earth's heat balance by preventing part of the sun's
reflected energy from returning back to space. As the C02 level increases, therefore,
more energy is retained and atmospheric temperatures rise.
CAUSE-EFFECT
NOT UNDERSTOOD
As with acid rains, the cause-effect relationship here is not well understood, at
least not well enough for us to exercise long-range policy judgments. Most scientists
who have studied the matter believe that the increases observed during the last
century were caused by rising consumption of fossil fuels; some others believe that
massive deforestation has contributed equally.
If current models describe the phenomenon with reasonable accuracy, rapid use
of the world's fossil fuel reserves could produce a seven-fold increase in the C02
level by the year 2200. A doubling of the level could occur in 50 years. Such a
doubling, it is estimated, could cause an average temperature increase of 2 to 3
degrees Celsius, a change that would pose a major environmental threat. To
illustrate, in the last 6,000 years, average mid-latitude temperatures in the Northern
Hemisphere have not varied by more than 1 degree above or below 15 Celsius.
COMPREHENSIVE ASSESSMENT
Although the full consequences of a 2-degree warming are highly speculative,
some obvious social and economic disruptions can be predicted. Agricultural belts
would shift toward the poles, and the melting of the ice caps could raise the sea
level. On the positive side, increases in rainfall and in CO2 might enhance
photosynthesis. We simply cannot anticipate all the implications of CO2 buildup at
this point, but we must learn, not only because the possible consequences are so
grave, but because we must develop some sense of the decisions that may have to
be made to deal with or avoid those consequences.
Here we return to the same place where acid rain deposited us: the need for a
comprehensive assessment of the problem. In the case of CO2 buildup, we have
more time to perform the assessment, but the costs will be greater: the larger the
environmental system, the more complex and costly the study requirements.
22
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MID-COURSE ENERGY
POLICY CORRECTIONS
SOLAR ENERGY
A RACE BETWEEN
CIVILIZATION AND DISASTER
In his National Energy Plan, President Carter stated the need for such an
assessment and assigned responsibility for it to the Department of Energy. DOE has
already developed a research plan and will invest about $4 million on the study in
the next 2 years. The results should give us the information on which to base
necessary mid-course corrections in international energy policies; the U.S. cannot
solve either the acid rain or CC>2 problems without the cooperation of other
countries.
The existence of these threats should also accelerate our development of
energy technologies that do not depend on fossil fuels, in particular, solar energy.
At present, most solar technologies are not cost competitive with fossil fuels. But if
our assessment of the acid rain and C02 problems proves them as serious as
scientific inference suggests, the economic as well as environmental costs of increased
fossil-fuel consumption might well transform solar energy into an overnight bargain.
You here are charged with conducting the research and development we need
to ensure that energy development proceeds without disrupting the natural systems
that support our lives. Certainly, the two problems I have outlined today are
capable of massive ecological disruption and unpredictable economic harm. They also
illustrate a most irritating aspect of environmental protection: as soon as we begin
to get a handle on one problem, a newcomer that we didn't even dream of appears.
Although we have been making progress on one environmental problem after
another, it is hard to convey that impression convincingly—especially to the lay
citizen—when we seem to be navigating a sea of environmental hazards, with no
shore in sight.
Henry Adams once described education as "a race between civilization and
disaster." In our time, and in view of the potential conflicts between energy
development and human well-being, that description seems even more true of your
research. So far, our citizens are with us. We must honor their trust by squeezing
the maximum of environmental protection from every dollar and every month they
give us. We must give substance to their expressed conviction that we can have a
healthy economy and a healthy environment at the same time. Unless we do, the
seemingly endless variety of environmental concerns may cause those who support us
to lapse into apathy.
We can't say "To hell with it." We have a race to win.
23
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chapter 2
health effects
-------
CHAPTER CONTENTS
health effects
STATUS OF BIOSCREENING OF EMISSIONS AND EFFLUENTS
FROM ENERGY TECHNOLOGIES
Michael D. Waters, Ph.D., US EPA
James L. Epler, Ph.D., Oak Ridge National Laboratory 29
THE EFFECTS OF H2SO4 ON MEN AND H2SO4 and O3
ON LABORATORY ANIMALS
Donald E. Gardner, Ph.D., US EPA
Milan Hazucha, M.D., US EPA
John H. Knelson, M.D., US EPA
Frederick Miller, Ph.D., US EPA 51
PANEL DISCUSSION:
David P Rail, M.D., Ph.D., U.S. Department of Health, Education and Welfare
Norton Nelson, Ph.D., New York University Medical Center
Kenneth Bridbord, M.D., U.S. Department of Health, Education and Welfare
William W. Burr, Jr., M.D., Department of Energy
Roy E. Albert, Ph.D., US EPA 63
QUESTIONS & ANSWERS 67
-------
HEALTH EFFECTS
STATUS OF BIOSCREEIMING OF EMISSIONS AND EFFLUENTS
FROM ENERGY TECHNOLOGIES
Michael D. Waters, Ph.D.
Health Effects Research Laboratory
U.S. Environmental Protection Agency
James L. Epler, Ph.D.
Biology Division
Oak Ridge National Laboratory
PROBLEM SOURCES
SHORT-TERM BIOASSAYS
ENVIRONMENTAL MEDIA
The National Energy Plan has affirmed that "The United States and the world
are at the early stage of an energy transition." This transition and the future
reliance on multiple sources of energy have provided the problem and the challenge
to "bioscreening" for health and ecological effects.
During the next 10 years, the major contribution to energy-related emissions
and effluents will be of a conventional nature. We will see increased combustion of
coal by conventional methods together with the gradually increased utilization of
alternative procedures such as fluidized-bed combustion. It is unlikely that the newer
technologies such as the gasification of coal, shale oil production, solar energy, and
nuclear fusion will have a major impact before the middle of 1980 (1).
Therefore, our bioassay methods must be geared to the evaluation of
conventional sources as well as to the newly evolving energy conversion technologies.
We have made significant progress in both areas as described in the proceedings of
the Second National Conference (2) but much remains to be accomplished.
Although our concern is with health as well as ecological effects, it is the
purpose of this presentation to examine the current status of short-term bioassays
which are applicable in studies of potential health effects of energy-related
technologies.
Short-term bioassays are being applied effectively in the detection and
evaluation of potentially hazardous emissions and effluents from conventional and
developmental energy sources, but, as yet, to a limited extent.
Biological screening tests such as the Ames Salmonella microsome assay (3)
have demonstrated their utility: 1) as indicators of potential long-term health effects
such as mutagenesis and carcinogenesis, 2) as a means to direct the fractionation and
identification of hazardous biological agents in complex mixtures, 3) as a measure of
relative biological activity to be correlated with changes in process conditions, and
4) to establish priorities for further confirmatory short-term bioassays, testing in
whole animals, and more definitive chemical analysis and monitoring.
Clearly, however, these tests do not circumvent the need for conventional
lexicological, clinical, and epidemiological evaluation. Likewise it is not possible to
divorce our vested concern for human health effects from a more basic concern for
the welfare of the ecological environment.
The introduction of emissions and effluents into the environment from energy
related technologies creates a multifaceted toxicological problem. The problem is a
function of the environmental media—i.e., air, water, food-and of the routes of
exposure. Indeed, mechanisms of toxic effects may be highly media or route
specific. Most exposures to hazardous agents in the environment are multiexposures;
that is, there are very few instances in which a singular substance or a single
29
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ENVIRONMENTAL EFFECTS
APPROACHES TO THE PROBLEM
CHEMICAL AND BIOLOGICAL
ANALYSIS
exposure is solely responsible for adverse health or environmental effects. Table 1
lists some general classes of chemicals with significant human exposure. Each of
these exposure factors must be taken into account in assessing the potential health
effects of energy related technologies.
Man is but a part of a total ecosystem. His well-being is utlimately dependent
upon the well-being of the system as a whole. Hence, it is critical to evaluate health
effects in man in the light of relevant and significant perturbations of the
ecosystem, especially those which directly influence exposure media including food,
water, and air.
Environmental effects may be slow to manifest themselves. Thus, our current
methods of disposal and recycling of toxic wastes and by-products may ultimately
compound the health and ecological effects of substances introduced into the
environment. We need to have detailed knowledge of the transport and fate of
environmental toxicants. Careful consideration of these factors is as important as
measuring the toxicity of the industrial discharge waste stream and must ultimately
be included in the assessment of the environmental impact of new technologies.
We have considered the components of the process of environmental
assessment in the broadest sense, i.e., the total impact of new technology on man
and his environment. The development of a rapid, effective, and inexpensive means
for evaluating the potential health hazards associated with emissions and effluents
from energy related technologies is a critical step in this process. Short-term
bioassays provide a means to this end but do not offer an independent solution to
the assessment problem.
It is clear that chemical and biological analysis have a dual role in the process
of environmental assessment. Each of these disciplinary approaches has its advantages
and limitations. Chemical analysis, while indicative, cannot provide sufficient data for
complete evaluation of potential pollutant effects; because the biological activity of
complex samples cannot be consistently predicted. Although bioassays can indicate
the biological activity of a given sample, they cannot specifiy which components of
a crude sample are responsible for the observed toxicity. A cost-effective approach
in screening involves the use of short-term bioassays to determine which samples are
biologically active together with chemical fractionation and analysis to ascertain
which agents are responsible for the observed effects. This was the theme of the
TABLE 1
General classes of chemicals with human exposure: potential environmental mutagens/carcinogens
DRUGS
• MEDICINAL
• VETERINARY
COSMETICS
PESTICIDES
STIMULANTS
FOOD
• ADDITIVES
• DYES
• PRESERVATIVES
• SWEETENERS
INDUSTRIAL PRODUCTS AND EFFLUENTS
ENERGY-RELATED EFFLUENTS
• ENERGY PRODUCTION
• ENERGY CONVERSION
• ENERGY USE
NATURAL PRODUCTS
• TOBACCO
• SOOT
FLAME RETARDANTS
Adapted from Epler, et al., Environmental Health Perspectives, 1978.
30
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METHODOLOGY
ASSESSMENT APPROACH
FINAL OBJECTIVE
recent Williamsburg Symposium (4) sponsored by the EPA Office of Energy,
Minerals and Industry through the Biochemistry Branch at EPA's Health Effects
Research Laboratory, Research Triangle Park, NC. The conference demonstrated that
short-term bioassay techniques can be used effectively to assess the biological
activity of complex samples and their components. Assays for toxicity, mutagenesis,
oncogenic transformation and related effects have been applied to an array of
complex samples including ambient air, water and food, automotive emissions,
industrial emissions, coal and its combustion products, and natural and synthetic oil
products. A major part of one of the Williamsburg papers is included in this report
as an example of the combined use of state-of-the-art biological and chemical
methodology.
In considering the application of analytical chemical methodology it is
important to realize that the presence or absence of a known toxic component
within a complex sample neither indicates nor precludes a relationship between that
component and the biological activity of the sample. To avoid the possibility of
overlooking unanticipated biologically active components chemical analysis should
not be restricted to determination of preselected known toxic compounds or
suspected hazardous components of a complex sample. Indeed, it may be technically
overwhelming to analyse for all of the known or suspected hazardous components in
a large number of complex samples. For this reason and for cost effectiveness, it
can be argued that a phased approach involving stepwise application of biological
and chemical methodology is appropriate in evaluating the potential health hazard of
complex mixtures.
The Industrial Environmental Research Laboratory of the Environmental
Protection Agency, Research Triangle Park, North Carolina (IERL-RTP), has
delineated a three-phased approach to performing an environmental source
assessment, i.e., the evaluation of feed and waste streams of industrial processes in
order to determine the need for control technology. Each of the three phases
involves a separate sampling and analytical procedure.
According to the plan outlined by IERL-RTP, (5-7) "The first level: 1)
provides preliminary environmental assessment data, 2) identifies problem areas, and
3) generates the data needed for the prioritization of energy and industrial processes,
streams within a process, and components within a stream for further consideration
in the overall assessment. The Level 2 sampling and analysis effort is designed to
provide additional information that will confirm and expand the information
gathered in Level 1. Level 1 results serve to focus Level 2 efforts. The Level 2
results provide a more detailed characterization of biological effects of the toxic
streams, define control technology needs, and may, in some cases, give the probable
or exact cause of a given problem. Level 3, utilizes Level 2 or better sampling and
analysis methodology in order to monitor the specific problems identified in Level 2
so that the toxic or inhibitory components in a stream can be determined exactly as
a function of time and process variation for control device development. Chronic,
sublethal effects are also monitored in Level 3.
"To meet the environmental source assessment requirement of
comprehensiveness, the IERL-RTP phased approach provides for physical, chemical,
and biological tests. Physical and chemical characterization of environmental
emissions is critical to the definition of need for and design of control technology.
However, the final objective of the Industrial Environmental Research Laboratory's
environmental assessment is the control of industrial emissions to meet
environmental or ambient goals that limit the release of substances that cause
harmful biological (health and ecological) effects. Consequently, the testing of
industrial feed and waste streams for biological effects is needed to complement the
physical and chemical data and ensure that the assessment is comprehensive."
This effort is cited as an example of a large scale phased application of
short-term bioassays and chemical analytical techniques to the analysis of complex
environmental samples. It represents an important beginning in an area of research
and application that will require continued intensive collaboration between engineers,
chemists and biologists if success is to be achieved. The results of Level 1 pilot
studies on samples from fluidized-bed combustion and coal gasification processes are
31
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HEALTH EFFECTS BIOTESTING
MUTAGEIMICITY/CARCINOGENICITY
TESTING
PHASED APPROACH
still being analyzed; a number of conclusions, however, can be drawn from the
results obtained thus far:
• In general, chemical analytical techniques are quantitatively more sensitive than
are the health effects bioassays.
• Biological activity, especially genetic activity, may be masked by toxicity and
may require chemical fractionation to become demonstrable.
• In some cases, tests for potential ecological effects may be more sensitive and
more critical than tests for potential health effects.
• The prediction of relative toxicity on the basis of chemical analysis alone is
subject to error.
• Results of biological and chemical tests are complementary considered
together the two types of tests provide useful information not obtainable when
considered separately.
There now exists a matrix of short-term health effects bioassays which can be
applied in a phased or stepwise manner in the biological analysis of energy related
samples. As with the IERL-RTP example, any program aimed at identifying and
reducing release of hazardous emissions or effluents requires the utilization of
inexpensive short-term bioassays to prioritize samples for further evaluation by
conventional toxicological procedures. However, it should be noted that some
short-term bioassays are known to be insensitive to specific chemicals or classes of
chemicals. Indeed, no single bioassay is adequate to monitor all types of chemical
and biological activity. The problem of potential false negatives may be alleviated by
the use of a required core battery of tests and by the identification, prior to
biological testing, of those samples which contain chemicals structurally or
physicochemically similar to known false negative agents or classes of agents. Such
agents or fractions of complex samples might then be selected for higher level
testing without the need for preliminary screening.
In the areas of mutagenicity and carcinogenicity testing, several variations of
the tiered or phased approach have been discussed in the literature (8)(10).
However, there is a considerable agreement on the essential point of emphasis at
each level of evaluation and on the need to employ a battery of tests to detect
various genotoxic effects, i.e., those effects involving damage to the genetic material.
For purposes of illustration and example we have organized a number of the
existing bioassays into a three-phased matrix based primarily on the endpoint
measured, cost and complexity. While the short-term bioassays that will be
mentioned are not to be considered exclusive, they do represent state-of-the-art
methodology. The refinement and implementation of many of these systems has
been a direct result of funding under the Interagency Energy/Environment R&D
Program.
A phased approach to bioscreening for environmental health effects
emphasizing kinds of bioassays is illustrated in figure 1. This is a three-step matrix
with a battery of tests at each level. The emphasis in the Phase 1 test battery is on
the detection of acute toxicity using mammalian cells in culture and intact animals,
genotoxic effects including point mutation and primary DNA damage in microbial
species, and chromosomal alterations in mammalian cells in culture. The Phase 2
battery is designed to verify the results from Phase 1 tests by employing higher level
toxicity tests involving mammalian cells in culture and intact mammals and
genotoxicity assays using plants, insects, and mammals. Genotoxicity assays at Phase
2 are separated into tests for mutagenicity per se and specific tests for carcinogenic
potential. Phase 3 testing is devoted to quantitative risk assessment, using
conventional toxicological methods. For the purpose of defining a probable negative
result for genotoxicity, the core battery of short-term tests is most important.
For the reason stated previously that no single test is capable of indicating all
of the various types of biological activity which may be relevant to the processes of
32
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MUTAGENESIS CARCINOGENESIS
PHASE 1
DETECTION
I Microorganisms (+/-Activation) I
Point Mutations J
/ Primary DNA Damage \
Mammalian Cells
Chromosomal Effects
PHASE 2
VERIFICATION
Mammalian Cells (+/-Activation)
Point Mutations
Primary DNA Damage
Mammalian Cells (+/-Activation)
Cellular Toxicity
Rodents
Acute Toxicity
Adsorption/D istribution
Metabolism/Excretion
Mammalian Cells (+/-Activation)
Cellular Metabolism
Insects & Plants
Point Mutations
Chromosomal
Effects
Rodents
Chromosomal
Effects
Rodents
Mammalian Cells (+/-Activation)| Subchronic Toxicology
Oncogen ic Transformation
Initiation/Promotion
Rodents (Skin)
Initiation/Promotion
Bioaccumulation
Cellular Toxicity
Organ Toxicity
Teratology Bioassay
PHASE 3
RISK
ASSESSMENT
Rodents
Chromosomal
Effects
Rodents
Carcinogenesis Bioassay
Rodents
Chronic Toxicology
I ["Core" Battery for
Mutagenesis/Carcinogenesis
FIGURE '\—A phased approach to bioscreening for environmental health effects
GENOTOXIC EFFECTS TESTS
POINT MUTATION
mutagenesis and carcinogenesis, it is generally held that a battery of short-term tests
should be performed. The battery approach is intended to reduce false negatives to
a minimum and thus assure reasonable protection of human health. Batteries of tests
have been proposed in the development of EPA's Pesticide Guidelines for
Mutagenicity Testing and in the Consumer Product Safety Commission's "Principles
and Procedures for Evaluating the Toxicity of Household Substances" (11). These
documents reflect the thinking expressed in the Committee 17 Report on
Environmental Mutagenic Hazards (12) and in the report of the working group of
the DHEW Subcommittee on Environmental Mutagenesis "Mutagenic Properties of
Chemicals: Risk to Future Generations" (13). There is considerable agreement that a
core battery of tests for mutagenic and carcinogenic effects should include, as
minimum, tests for point mutation in microorganisms and mammalian cells in
culture; a test for chromosomal alterations, preferably in in vivo test; a test for
primary damage to DNA using mammalian, preferably human, cells in culture and a
test for oncogenic transformation in vitro. Such a battery of tests might be
considered to represent the core or the most essential of the genotoxicity tests in
the phased evaluation process. Redundancy in the test battery is considered desirable
until a more complete data base of test results has been assembled. Also, to aid in
interpretation, it is necessary to ascertain the influence of cellular toxicity in these
tests. The following is a description of the kinds of biological activity detectable in
short-term tests comprising the core battery.
Point mutations are alterations which affect single genes. These alterations
include base pair substitutions, and frameshift mutations as well as other small
deletions and insertions. Applicable test systems include both forward and reverse
33
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mutation assays in bacteria, yeast, and mammalian cells in culture. Most of these
assays employ an exogenous source of metabolic activation provided by a
mammalian liver microsomal preparation. It has become apparent that a majority of
the genotoxins are procarcinogens or promutagens which must be converted into
their reactive forms before their effects can be evaluated. The metabolic conversion
is believed to be mediated by oxidative enzymes and to involve the formation of
reactive electrophilic metabolites which bind covalently to DNA. Gene mutation
assays which incorporate whole animal metabolic activation (e.g., urine screening) are
very desirable since it is not possible to ensure metabolic fidelity in entirely in vitro
systems. One must employ intact animals to demonstrate the heritability of
mutational effects.
CHROMOSOMAL ALTERATIONS
Chromosomal alterations include the loss or gain of entire chromosomes,
chromosome breaks, non-disjunctions and translocations. Short-term tests for these
abnormalities involve searching for chromosomal aberrations in somatic and germinal
cells usually from insects and mammals. Chromosomal aberrations observed in
germinal tissues of intact animals provide important evidence of the accessibility of
the test chemical to the reproductive organs.
Damage and repair bioassays do not measure mutation directly but do measure
the direct damage to DNA and other macromolecules by chemical agents and its
subsequent repair. Bioassays to detect macromolecular damage and repair are
available, using bacteria, yeast, mammalian cells, and whole animals. Except for the
whole animal bioassays, these systems generally employ an exogenous source of
metabolic activation.
Oncogenic transformation is the process whereby normal cells grown in culture
are converted into malignant cells after treatment with a carcinogen. The
demonstration of malignancy (tumor formation) can be observed by injecting the
transformed cells into whole animals, although this is not an obligatory requisite for
oncogenic transformation. A number of mammalian oncogenic transformation
bioassays utilizing cells derived from different rodent species are currently available.
Some of these cell systems have the endogenous capability to activate procarcinogens
while with others exogenous microsomal activation has been used successfully.
TOXIC ITY IN VITRO
An initial requirement in mammalian cell mutagenesis and oncogenesis
bioassays is the determination of the lethal toxicity of each test agent. This
information may be used to establish the range of concentrations to be employed in
the mutagenesis or oncogenesis assays and to quantify the observed mutation or
transformation frequency in terms of the number of cells surviving the treatment.
Two critical questions are: How good are these genotoxicity tests and what do
they mean?
CARCIIMOGENESIS
At the present time, microbial mutagenesis test systems are most widely used
to prescreen substances for potential oncogenicity. Tests for gene or point mutations
in microorganisms, as for example those involving the Salmonella
typhimurium/microsome system, have been found to be highly predictive of
oncogenic potential (14). Most chemical mutagens which have been adequately tested
have been found to be oncogenic in whole animal bioassays. It is well established
that most but not all oncogens are mutagens when appropriate metabolic activation
is provided in the short-term tests. Research on test systems which permit sequential
evaluation of mutagenesis and oncogenic transformation has enhanced our
understanding of the relationship between these two phenomena.
Oncogenic transformation in vitro is considered to be directly relevant to the
process of tumor formation in the intact animal. Few, if any, false positives are
detected using this methodology (15). However, because of the laborious nature of
cell transformation assays, it may not be feasible because of time or fiscal
constraints or the availability of facilities to immediately put a very large number of
samples through such testing procedures. It is for reasons such as these that
oncogenic transformation assays are generally considered to be higher level tests.
34
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When more fully developed, human cell bioassays for oncogenic transformation
may afford a final short-term test for substances found positive in phylogenetically
lower organisms. This will be true especially if epithelial cell systems can be
developed which retain their metabolic activation capability. Those chemicals which
produce positive responses in human cell systems might be given highest priority for
evaluation in conventional whole animal oncogenesis bioassays.
MUTAGENESIS
The fundamental concern in mutagenesis testing is the risk to future
generations. Alterations of the genetic material in germinal cells are rarely expressed
in the exposed individuals. These alterations may not become apparent for several
generations but they contribute to an increased genetic burden in the exposed
population. The observation and quantitation of these mutational effects in germinal
tissues requires the use of intact animals, e.g., the sex-linked recessive lethal test in
the \nsectDrosophila (16). It would be highly desirable to include such a test in the
core battery if significant human exposure is anticipated to a suspect mutagen.
The usefulness of cells other than germinal cells as a predictive tool is judged
to be high for certain kinds of genetic alterations. Microbial cells are widely used to
detect point mutagens. Many of these systems have been genetically engineered to
enhance their sensitivity as detection systems. Mammalian and human cells in culture
can provide more relevant information on the ability of the substance to induce
both point mutations and chromosomal alterations. It is important to evaluate both
types of potential genetic activity. Chromosomal alterations are best evaluated in
intact animals but inexpensive whole animal tests for point mutagens are lacking.
ANCILLARY EFFECTS
Tests which detect primary damage to informational cellular macromolecules
(e.g., DNA) have been found to show moderate to high correlation with mutagenic
and oncogenic potential as indicated by animal bioassays (17,18). Microbial tests in
this category are extremely rapid and inexpensive and offer the possibility of
examining various manifestations of macromolecular damage. Mammalian and human
cell culture bioassays for primary DNA damage offer the possibility of detecting
macromolecular damage in tests which have demonstrated promising correlations with
mutagenic and oncogenic potential as evaluated using experimental animals (19).
Several of these systems permit concomitant measurement of primary DNA damage,
point mutation, chromosomal effects and cellular toxicity. The Interagency R&D
Program is continuing to support developmental research of this kind.
As indicated previously, a phased mode of application has been favored as a
cost effective approach to the bioscreening of large numbers of complex
environmental samples and their components.
BIOASSAY STRATEGY
A strategy for the employment of short-term bioassays based on biological
activity, cost and complexity may be delineated as follows:
In Phase 1, tests representing each kind of biological activity would be
performed. The extent of redundancy in testing within a category of biological
activity would be dictated by a number of factors including production volume,
anticipated human exposure, and known hazards of feed stocks. If any of these tests
proved positive, the appropriate follow up tests would be pursued in Phase 2 and, if
required, in Phase 3 depending upon the degree of associated risk. If those tests
were to prove negative, no further testing would be performed unless there were
overriding considerations as mentioned previously. In such cases a core battery of
tests for genotoxicity would be completed with negative results before short-term
testing would cease. Extensive health risk could entail further long-term testing to
define a negative result. This approach would facilitate a cost effective utilization of
limited testing resources and would at the same time provide protection for human
health in proportion to the anticipated risk involved.
35
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PHASE 1 BIOASSAYS
PHASE 2 BIOASSAYS
PHASE 3 BIOASSAYS
Specific tests may be organized within the test matrix as follows:
A battery of short-term tests for this phase is illustrated in figure 2. As
mentioned previously, the emphasis at this level of testing is on detection of
mutagens, potential carcinogens and acutely toxic chemicals in a battery of in vitro
and in vivo tests. The results obtained from Phase 1 tests are used to assign
priorities for further testing in appropriate confirmatory bioassays at Phase 2. The in
vitro end points that are considered, based upon expense, complexity, and the
current level of development of bioassay systems, are point mutations, chromosomal
alterations, primary DNA damage, and cellular toxicity. All bioassays are performed
with and without mammalian metabolic activation systems where feasible.
Conventional rodent acute toxicity tests are considered essential at Phase 1 in view
of the limitations of cytotoxicity screening tests. The latter tests cannot represent
intact animals but provide useful preliminary information about the relative cellular
toxicity of selected samples (e.g. airborne particulate materials (20). In addition,
rodent acute toxicity tests can provide a source of body fluids and tissues to be
examined for the presence of active mutagens and carcinogens by the use of
short-term genotoxicity bioassays.
As mentioned previously, Phase 2 tests illustrated in figure 3 are designed to
verify the results obtained in Phase 1. The test systems are selected to provide
confirmatory information on point mutations, chromosomal alterations, primary
DNA damage and repair, and cellular oncogenic transformation. The latter test
provides more explicit information on the carcinogenic potential of a sample. The
test organisms are mammalian cells in culture supplemented with exogenous
metabolic activation, plants, insects, and intact mammals. These systems are
considered to provide more relevant and definitive information in the continuing
process of health hazard evaluation, especially where intact organisms are employed.
Phase 3 testing involves the use of conventional whole animal methods. The
emphasis here is on quantitative risk assessment. Experimentation with intact
mammals is needed to provide information on the presence, concentration, and
biological activity of toxins in the target tissues. In addition, information on
pharmacokinetics involving absorption, distribution, metabolic transformation, and
excretion cannot be obtained without studies using intact mammals.
36
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POINT MUTATIONS
• SALMONELLA/MICROSOME (AMES) REVERSE MUTATION,
PROTOTROPHY TO HISTIDINE
• ESCHERICHIA COLI-WP2/MICROSOME REVERSE MUTATION,
PROTOTROPHY TO TRYPTOPHANE
• SACCHAROMYCES CEREVISCIAE REVERSE AND FORWARD
MUTATION
CHROMOSOMAL EFFECTS
• IN VITRO CYTOGENTICS
CHINESE HAMSTER OVARY CELLS
WI-38 HUMAN FIBROBLASTS
PRIMARY DNA DAMAGE
• ESCHERICHIA COLI POL A" REPAIR DEFICIENT STRAINS
• BACILLUS SUBTILLIS, REC" REPAIR DEFICIENT
STRAINS
• SACCHAROMYCES CEREVISCIAE GENE CONVERSION AND
MITOTIC RECOMBINATION
CYTOTOXICITY
• RABBIT ALVEOLAR MACROPHAGE (FOR PARTICULATES)
• CHINESE HAMSTER OVARY CELLS
• WI-38 HUMAN LUNG FIBROBLASTS
RODENT ACUTE TOXICITY
FIGURE 2—Phase 1 short-term bioassays for mutagenesis/carcinogenesis/toxicity
POINT MUTATIONS
• MAMMALIAN CELLS IN CULTURE (CHO, L5178Y, V79)
• INSECTS-DROSOPHILA
• PLANT-TRADESCANTIA AND MAIZE
CHROMOSOMAL EFFECTS
• IN VIVO CYTOGENETICS - LEUCOCYTE CULTURE AND
BONE MARROW CELLS
PRIMARY DNA DAMAGE
• UNSCHEDULED DNA SYNTHESIS (WI-38)
• SISTER-CHROMATED EXCHANGE FORMATION (IN VITRO
AND IN VIVO]
NEOPLASTIC TRANSFORMATION
• SYRIAN HAMSTER EMBRYO CELLS
• MOUSE FIBROBLAST CELL LINES (C3H10T1/2 AND
BALB/c 3T3)
CELLULAR METABOLISM
• PRIMARY LIVER CELLS
(RODENT SUBCHRONIC TOXICOLOGY)
(TERATOLOGY)
FIGURE 3—Phase 2 short term bioassays for mutagenesis/carcinogenesis/toxicity
37
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The resource implications of a mutagenicity/carcinogenicity bioscreening
program are shown in table 2. It is evident that most of the short-term bioassays
designed to detect point mutation, chromosomal alterations in vitro and primary
DNA damage and repair are relatively rapid, inexpensive, and require small amounts
of test material. Together with cytotoxicity bioassays for selected applications and
rodent acute toxicity tests these bioassays constitute effective screens for toxic and
genotoxic effects of energy related emissions and effluents.
SYNTHETIC FUEL PRODUCTS
BIO ASS AY
As we have reported previously (2), a number of mutagenicity/carcinogenicity
bioscreening efforts related to energy technologies are now underway. In work
conducted at Oak Ridge National Laboratory, the feasibility of using short-term
mutagenicity assays to predict the potential biohazard of various crude and complex
test materials has been examined in a coupled chemical and biological approach. The
research program was not deliberately structured according to the three-phased
matrix outlined above. However, it does provide an appropriate example of the
stepwide application of bioscreening methodology to energy related samples and
provides some documentation of comparative mutagenesis responses to such samples.
This work has emphasized test materials available from the developing
synthetic fuel technologies (21). However, the procedures are applicable to a wide
variety of industrial and natural products, environmental effluents, and body fluids.
The principal focus of the research has been preliminary chemical
characterization and preparation for bioassay, followed by testing in the Salmonella
histidine reversion assay described by Ames (3).
The general applicability of microbial test systems has already been
demonstrated, for example, by the use of the assay as a prescreen for potential
genetic hazards of complex environmental effluents or products, e.g., tobacco smoke
condensates (22) natural products (23,24) hair dyes, (25) soot from city air, (26)
fly ash, (27) and synthetic fuel technologies, oils, and aqueous wastes (28,29).
To study the application of mutagenicity testing to environmental effluents
and crude products from the synthetic fuels technology, preliminary screening was
performed with the highly sensitive Ames histidine-reversion strains known to
respond to a wide variety of proven mutagens/carcinogens (26). The working
hypothesis was that sensitive detection of potential mutagens in fractionated
complex mixtures could be used to isolate and identify the biohazard. In addition,
the information could be helpful in establishing priorities for further testing, either
with other mutagenesis assays or with carcinogenesis assays.
BIOASSAY METHOD
Fractions and/or control compounds to be tested were suspended in dimethyl
sulfoxide to concentrations in the range of 10-20 mg/ml solids. The potential
mutagen was in some cases assayed for general toxicity (bacterial survival) with
strain TA1537. Normally, the fraction was tested with the plate assay over at least a
1000-fold concentration range with the tester strains TA98 and TA100. Revertant
colonies were counted after a 48-hour incubation. Data were recorded and plotted
versus added concentration, and the slopes of the induction curves were determined.
It is assumed that the slope of the linear dose-response range reflects the mutagenic
activity. Positive or questionable results were retested with a narrower range of
concentrations. All studies were carried out with parallel series of plates with and
without the rat-liver enzyme preparation (24) for metabolic activation. Routine
controls demonstrating the sterility of samples, enzyme or rat-liver S-9 preparations,
and reagents were included. Positive controls with known mutagens were also
included in order to recheck strain response and enzyme preparations. All solvents
used were nonmutagenic in the bacterial test system.
38
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TABLE 2
Resource implications of carcinogenicity/mutagenicity bioscreening program
Test
Bacteria
(Ames plate test)
Bacteria
(liquid suspension)
Eukaryotic micro-
organisms (yeast)
Insects (Drosophila,
recessive lethal)
Mammalian somatic cells
in culture (mouse
lymphoma)
Mouse specific locus
In Vitro cytogenetics
In Vitro cytogenetics
Insects, heritable
Chromosomal effects
(Drosophila) non-
disjunction
Dominant lethal in
rodents
Heritable transloca-
tion in rodents
DNA repair in bacteria
Unscheduled DNA synthesis
Mitotic recombination
and/or gene conversion
in yeast
Sister chromitid
exchange
$ Cost*
Gene (Point) Mutations
350 - 600
1,000 - 2,000
200 - 500
6,000 - 7,500
2,500 - 4,800
20,000+
Chromosomal Mutations
1,000 - 2,000
3,000 - 6,500
3,000 - 6,500
3,000
6,000 - 10,000
40,000 - 67,000
Primary DNA Damage
200 - 500
350 - 2,000
200 - 500
1,000 - 1,200
Study
Time f
2—4 weeks
2—4 weeks
2—4 weeks
4—6 months
1—2 months
1 year
2—4 weeks
6-8 weeks
4—6 weeks
1-3 months
3 months
12-18 months
2—4 weeks
4—6 weeks
4—6 weeks
4—6 weeks
Quantity of
Material
Required
2 g
2 g
2 g
10 g
2 g
25 g
2 g
20 g
10 g
20-25 g
25 g
2 g
2-5 g
2-5 g
2-5 g
Oncogenic Transformation In Vitro
Chemically induced
transformation
6,500 - 7,500
10-12 weeks
2-5 g
* Cost of these tests has varied and can be expected to vary
until test requirements are stabilized.
f This time period covers the experimental time and report
preparation.
39
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TABLE 3
Distribution of mutagenic activity of synthetic oil* (Synfuel A-2)
Fraction' Relative Weight
(% of total)
1. NaOH|
2. WA|
3. WAE
4. SA|
5. SAE
6. SAW
7. B|g
8. B,b
9. BE
10. BW
Neutral
Total
Neutral Subfractions
Hexane
Hexane/benzene
Benzene/ether
Methanol
Subtotal
Initial sample, g
Chromatographed, g
20.9
2.2
4.9
<0.1
0.4
0.4
6.8
0.1
2.0
0.6
69.2
107.6
72.7
5.0
19.8
2.3
99.8
26.166
10.664
Specific Activity Weighted Activity
(rev/mg)$ (rev/mg)§
1700
180
1260
30
130
120
38700
1270
36200
570
583 (570)**
340
710
1360
1460
356
4
62
0
1
1
2633
1
725
3
403
4189
244
35
270
34
583
All assays carried out in the presence of crude liver S-9 from rats induced with
Aroclor 1254.
' I = insoluble (fractions a and b), E = ether soluble, W = water soluble, WA =
weak acid, SA = strong acid, B = base.
+ rev/mg = revertants/mg, the number of histidine revertants from Salmonella
strain TA98 determined by use of the plate assay with 2 X 10** bacteria per
plate. Values are derived from the slope of the induction curve extrapolated
to a milligram value.
§ Weighted activity of each fraction relative to the starting material is the
product of columns 2 and 3. The sum of these products is given as a measure of
the total mutagenic potential of each material.
Comparable to "specific activity", but based on the activity of the total neutral
fraction rather than on the summation of the individual fractions.
SAMPLES
Samples that have been tested and their sources are listed in tables 3 and 4.
The authors recognize the possibility that these samples may bear no relationship to
the process as it may exist in the future, nor should it be construed that these
materials are representative of all natural crudes or synthetic or shale-oil processes.
They are used here simply as appropriate and available materials for the research.
The bulk of the samples listed above were subjected to the fractionation
scheme described by Swain et al., (30) as modified by Bell et al. (31). The scheme
is described in detail as applied to oils in Rubin et al. (32). As an example, a
40
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ACTIVITIES COMPARISON
ROUTINE SCREENING
summary of the results from a sample of Synfuel A-2 (ref. 28) is given in table 3.
Subfractionation results are shown with the neutral fraction chromatographed on a
Florisil column. The column was eluted with the solvents shown and, with this
sample, collected in one fraction. The data include the analytical weight analysis of
the sample (column 2) and the specific mutagenic activity (slope of the
dose-response curve) of each fraction (column 3). The product of these (column 4)
represents a weighted value of each fraction relative to the contribution to the
starting test material. Mutagenic activity is seen in both the acidic and basic
fractions as well as in the neutral subfractions. However, the major contributors to
the mutagenicity appear to occur in the basic fractions, with activities also
consistently present in the neutral materials.
A comparison of these activities and the total mutagenic potential of the
various oil and aqueous samples is given in table 4. Reasonable reproducibility is
seen in similar samples, e.g., Synfuel A-1 and A-2; Synfuel B-1 and B-2. Synfuel A-3
represents the same material without prior centrifugation of the solids. The
consistency of activities seen in all oils considered is illustrated. On a relative scale,
the synthetic fuels show more mutagenic activity than the natural crude control
samples shown. Shale oil appears to be only slightly higher than the natural crudes.
References are given to the complete published compilations on these samples.
Each determination represents the slope of the dose-response curve. All testing
was carried out in the presence of the rat-liver microsomal activation system. Slight
mutagenic activity without enzyme treatment was occasionally noted.
The routine screening utilized strains TA100 (missense) and TA98 (frameshift);
however, complete strain-specificity tests were carried out with selected materials.
Fractions giving a positive response with strain TA98 were, in general, also positive
with the other frameshift strains, TA1537 and TA1538. Positive results were
routinely noted with the sensitive missense strain TA100; however, reversion of the
TABLE 4
Summary of mutagenicity testing results with synthetic oils and aqueous samples-class
fractionation scheme*
SAW
Neutral
Sample
Composite crude-1
Composite crude-2
La. -Miss, crude
Shale oil
Synfuel A-1
Synfuel A-2
Synfuel A-3
Synfuel B-1
Synfuel B-2
Separator Liquor,
1.3 w/v%
Gasifier condensate,
0.9 w/v%
Process water (shale
oil), 1.0 w/v%
Relative
Weight
(%)
0.1
0.1
0.1
0.6
0.3
0.4
0.3
0.4
1.6
53.9
30.8
65.0
Specific
Activity
(rev/mg)
400
750
240
160
240
120
1010
0
0
0
0
0
Relative
Weight
(%)
0.2
0.2
0.2
7.1
2.0
2.0
3.1
2.6
1.8
0.5
0.5
2.7
Specific
Activity
(rev/mg)
150
500
180
952
28900
36200
43300
1500
3800
850
4000
1575
Relative
Weight
(%)
84.2
84.2
80.7
86.7
73.6
69.2
56.4
82.3
89.3
1.5
1.9
2.4
Specific
Activity
(rev/mg)
277
166
90
112
517
583
1094
560
465
0
100
52
Total
Weighted
Activity
(rev/mg)
241
147
76
178
4032
4189
7308
516
484
17
211
68
Reference
9
10
9
10
9
9
9
9
9
unpublished
14
10
*Strain TA98 metabolically activated with Aroclor-induced preparation
41
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VALIDATION
AQUEOUS SAMPLES
OTHER METHODS
missense strain TA1535 was rare. TA98 appeared to be the best general indicator of
mutagenic activity of these materials. Furthermore, liver preparations from rats
induced with Aroclor 1254 showed the best general applicability. However,
individual differences in effectiveness do occur, for example, variously induced
preparations show obvious differences between basic fractions and, e.g., the
neutral/methanol fraction (28). An Aroclor-induced preparation reacts best with the
neutral fraction (polynuclear aromatic hydrocarbons?), while a phenobarbital-induced
preparation works more efficiently with the basic fraction (heterocyclic nitrogen
compounds?).
Primary candidates for the mutagens (and carcinogens?) responsible for activity
in the basic fractions include quinoline, substituted quinolines, alkyl pyridines,
acridine, naphthylamines, aza-arenes, benzacridines, and aromatic amines; in the
neutral fractions, potential threats may be benzanthracenes, dibenzanthracenes,
substituted anthracenes, benzopyrenes, benzofluorenes, pyrene, substituted pyrenes,
and chrysenes (33,34). Thus, work with these pure compounds is being carried out
concurrently.
Reproducibility of results was shown by comparison of data from similar
samples. Although discrepancies exist from fraction to fraction, the general trend is
apparent and the sum of activities appears to be roughly reproducible. Again, when
the major-component, neutral fraction is assayable, as with the Synfuel A, the
summation of the subfraction values of the neutrals reflects the approximate
additivity of the individual mutagenic determinations. For example, 570
revertants/mg with a direct assay of the neutrals from Synfuel A-2 compares with
583 revertants/mg based on the summation (table 3).
An overview of the results points to a number of consistencies: 1) all crudes
and Synfuels showed some mutagenic potential; 2) the neutral and basic fractions
showed activities regardless of the source of the sample; and 3) the relative total
mutagenic potentials varied over two orders of magnitude. Whether these results
reflect a comparative biohazard of processes still under development is not the point
in question here. The results simply show that biological testing—genetic reversion
assays in this case—can be carried out with the newly developed tester systems, but
only when coupled with the appropriate analytical separation schemes. Conceivably,
the use of this approach could rapidly provide information concerning health effects.
Table 4 also lists sample results from a group of aqueous samples subjected to
the class fractionation procedure (Stedman procedure). In general, greater activity is
seen in the more polar, more water-soluble fractions rather than in the nonpolar
neutral materials. Caution must be used in work with any aqueous material because
of the high potential for instability. Although we have used organic extraction here,
techniques with resin concentration, e.g., XAD-2, may prove useful with aqueous
samples (35,36). Only in exceptional cases is the mutagenic activity directly
observable in an unconcentrated sample.
In the initial studies with coal-liquefaction products, the crude oils were
fractionated by the use of the scheme originally developed for cigarette smoke
condensates (Stedman procedure). The scheme yields class separations based on the
relative acid-base properties of the components. The samples are partitioned between
ethyl ether and 1 N NaOH in a single-stage, continuous procedure to yield an
aqueous acid fraction and organic-phase base and neutral fractions. The organic
fraction is extracted with 1 N HC1 to yield an aqueous basic fraction, an organic
basic fraction, and an organic neutral fraction. The neutral material is subsequently
subfractionated on a Florisil column. These primary subfractions are then subjected
to mutagenicity testing.
Realizing the potential for modification of the components inherent in this
procedure, consideration was given to a number of other fractionation methods. The
fractionation procedures using Sephadex LH-20 can provide a gentle and large-scale
class separation for (initially) crude oils from shale-oil and coal-liquefaction
processes. The procedure involves three steps, using the gel in different modes: 1)
lipophilic-hydrophilic partitioning, 2) molecular size separation, and 3)
42
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TABLE 5
Sephadex LH-20 fractionation of shale oil coupled with mutagenicity testing
Test Material
Percent of Total Specific Activity*
(rev/mg)
Crude oil
Hydrophilic
Lipophilic
Polymer
Hydrogen-bonding
Sieved
Polymer
Aliphatics
Aromatics
1 and 2 rings
3 and 4 rings
Polynuclear
100
6
93
5
5
84
1
60
14
5
4
233
1300
196
54
1040
100
0
180
24
132
1220
*Slope of dose-response curve with Salmonella strain TA98 plus liver
preparation from rats induced with Aroclor 1254.
aliphatic-aromatic separation. The procedure (37,38) was designed by Jones, Guerin,
and Clark of the Analytical Chemistry Division, ORNL. Using fractions prepared as
above, we have started a comparison of this procedure and the Stedman procedure
for usefulness in preparation for bioassay. The preliminary mutagenicity studies
confirm the suitability and utility of the method. Table 5 summarizes some of the
results from shale oil. The method appears to be generally applicable to complex
organic mixtures and achieves the goal of providing a gentle and rapid separation
scheme which is useful with large-scale samples.
SUBFRACTIONATION
Again, considering the results with class fractionation procedures, a procedure
(39) was developed specifically designed for subfractionation of the basic materials,
now realized to be a major contributor to mutagenic activity. An elution sequence
using alumina and Sephadex LH-20 gel with a combination of solvents isolates 90
percent of the mutagenic activity from basic compounds into a 0.5 wt percent
fraction of crude oil.
A basic alumina column eluted first with benzene and then ethanol isolates the
mutagenic compounds of the ether-soluble base fractions of synthetic crude oils into
a fraction of about 25 wt percent of the ether-soluble base. A further separation is
achieved by eluting the ethanol isolate through a Sephadex LH-20 gel column with
isopropanol followed by acetone. About 90 percent of the basic mutagenic activity
is recovered in the acetone subtraction, which comprises ~ 0.5 wt percent of the
crude oil. Development of this separation scheme was made possible by use of the
Ames microbial mutagenesis assay as the detector during exploratory
liquid-chromatographic separations.
COMPARATIVE MUTAGENESIS
To validate and compare the results accumulated in the Ames system with
complex test materials from synthetic fuel technologies, specific fractions or
subfractions were selected on the basis of their activity in the histidine-reversion
assay for further testing in the various other assays designed to detect mutagenicity.
Preliminary results have been published in the Proceedings of the Second
43
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TABLE 6
Comparative mutagenesis of fractions from synthetic crude oils*
Test system
Salmonella
E. coli
Yeast
Drosophila
CHO cells
Human leucocytes
Mouse
Assay Basic Neutral
Fraction Fraction
+
his> his + +
arg~* arg + +
+
gal •> gal + +
his"* his + +
CAN5* canR + +
sex-linked recessive + —
lethal
6-thioguanine resistance + NT
chromatid aberrations P +?
sister chromatid exchange + +?
dominant lethalsj — P
skin painting§ P P
(carcinogenesis)
Crude
Synfuelf
+
NT
NT
NT
NT
NT
NT
NT
NT
+
P
* For references to published work or work in progress see text. The fractions
utilized were generally those from Synfuel A-3 or Synfuel B-2. + = mutagenic;
= nonmutagenic; NT = not tested; P = in progress.
f Crude synfuels are generally too toxic to test in most systems.
J Work or W. M. Generoso, ORNL, in progress.
§ Work of J. M. Holland, ORNL, in progress.
International Conference on Environmental Mutagens, Edinburgh, 1977 (40). The
results are given in table 6 for qualitative comparison. The selected fractions or
subfractions utilized were basic and neutral isolates from synthetic crude oils from
coal-liquefaction processes-Synfuel A and B as described in Epler et al (11). For
Drosophila (41) and for the mammalian cell gene mutation assay (40), detection has
been a function of newly developed fractionation schemes, (e.g., the use of LH20)
(37,39) that result in higher-specific-activity (more highly purified) mutagenic
subfractions. In general, the results validate the initial screening carried out in the
Salmonella assay, but these other systems have not as yet been used to exhaustively
test materials that are negative in the Ames system. Note, also, however, that the
preliminary results of Generoso (personal communication) show that the crude
synthetic fuel does induce dominant lethals in mice, although the basic fraction
alone appears to be negative.
SYNFUEL FRACTIONS For the comparative studies with microbial systems given here, four Synfuel
fractions were selected. The results with the metabolically activated frameshift strain
TA98 were considered. Fractions #6 (SAw), #7 (B|a), #9 (Be), and
neutrals/methanol were selected on the basis of their ability to revert the Ames
strains. To validate the mutagenicity results obtained from the Salmonella
histidine-reversion system, we extended the treatment with the selected test fractions
to the E. coli 343/113 system of Mohn (43). The results obtained in the forward-
(gal+) and reverse-mutation (arg+) assays with E. coli support the results obtained
with Salmonella. Both the basic fraction (#9) and the neutral/methanol subfraction
are mutagenic upon metabolic activation with Aroclor-induced rat-liver homogenate
(S-9).
44
-------
FURTHER VALIDATION
SUMMARY
CONCLUSIONS
Further validation of the bacterial results was obtained by assaying for both
forward and reverse mutation in the yeast system (40,44). The Synfuel A fractions
tested were weakly mutagenic and were effective without metabolic activation. Some
antagonistic effects were encountered when metabolic activation was incorporated.
The most active fraction, B^, also reverted the putative frameshift marker, horn3-10.
This fraction may contain acridines and other nitrogen heterocyclics. Unpublished
results from our group point to similar effectiveness without activation in the
Salmonella system when suspension tests rather than plate assays are used with
crude mixtures.
Selected test fractions from Synfuel B were assayed in the Drosophila
sex-linked recessive lethal system. The acetone fraction from the basic material is
effective as a mutagen for Drosophila at the higher concentrations fed (41).
In summary, short-term tests with bacterial and yeast mutagenicity assays
appear to detect effectively the mutagenic potential of complex environmental or
industrial effluents; however, chemical fractionation is necessary to reduce toxicity
and concentrate hazardous materials. Extension of the results to higher organisms,
i.e., mammalian cells, Drosophila, and the mouse, appears to be valid but needs
more testing.
In these initial feasibility studies, the purpose has not been to reflect on
whether a relative biohazard exists in comparison with other materials or processes.
The results show that biological testing within the limits of the specific system
used can be carried out with complex organic materials, but perhaps only when
coupled with the appropriate analytical separation schemes. An extrapolation to
relative biohazard at this point would be, at least, premature. The primary use that
such combined chemical and biological work may serve is to aid in isolating and
identifying the specific classes or components involved. A number of precautions are
listed below.
The detection or perhaps the generation of mutagenic activity may well be a
function of the chemical fractionation scheme utilized. The inability to recover
specific chemical classes or the formation of artifacts by the treatment could well
corrupt the results obtained, as could an inability to detect the specific biological
end point chosen. Along with the obvious bias that could accompany the choice of
samples and their solubility or the time and method of storage, a number of
biological discrepancies could also enter into the determinations. For example,
concomitant bacterial toxicity could nullify any genetic damage assay that might be
carried out; the choice of inducer for the liver enzymes involved could be wrong for
selected compounds; the choice of strain could be inappropriate for selected
compounds. Furthermore, the applicability of the generally used Salmonella test to
other genetic end points and the validation of the apparent correlation between
mutagenicity and carcinogenicity still needs validation through sufficient fundamental
research. The short-term assays chronically show negative results with certain
substances, e.g., heavy metals and certain classes of organics. Similarly, compounds
involved in or requiring co-carcinogenic phenomena would presumably go undetected.
However, as a prescreen to aid the investigators in ordering their priorities, the
short-term testing appears to be a valid testing approach with complex mixtures.
Overinterpretation at this stage of research, especially with respect to relative hazard
or negative results, should be avoided.
Several general conclusions may be reached on the basis of the foregoing
discussion:
• Short term bioassays are being applied effectively to energy related samples as
indicators of potential health effects.
• These tests facilitate rapid prioritization of samples for further evaluation by
conventional biological and chemical methodologies.
• The bioassays are useful as a means to direct the chemical fractionation and
identification of hazardous components of complex mixtures.
45
-------
• Chemical fractionation may be required for the demonstration of genetic or
genotoxic activity in complex mixtures which contain interfering toxic
components.
• The prediction of relative toxicity on the basis of chemical analytical results is
subject to error.
• However, chemical analyses are, in general, quantitatively more sensitive than
are the health effects bioassays.
• The results of chemical and biological analysis are complementary and together
provide useful information not obtainable when the two approaches are applied
separately.
ACKNOWLEDGMENTS
Research supported through the Environmental Protection Agency, Office of
Energy, Minerals and Industry.
Research jointly sponsored by the Environmental Protection Agency (IAG-D5-
E681; Interagency Agreement 40-516-75) and the Division of Biological and
Environmental Research, U.S. Department of Energy, under contract W-7045-eng-26
with the Union Carbide Corporation.
The authors thank the staff at the Pittsburgh Energy Research Center and the
Laramie Energy Research Center for their cooperation in providing samples.
The authors acknowledge the extensive participation of their colleagues in this
work. The authors thank the staff of the Biochemistry Branch, Health Effects
Research Laboratory, and the Industrial Environmental Research Laboratory,
Environmental Protection Agency, Research Triangle Park, North Carolina; the
Biology Division and the Analytical Chemistry Division of the Oak Ridge National
Laboratory for providing data, both published and unpublished.
46
-------
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26. Ames, B. N., J. McCann, and E. Yamasaki. "Methods for detecting
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49
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41. Nix, C. E. and B. S. Brewen. "The role of Drosophila in chemical
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42. Hsie, A. W., J. P. O'Neill, J. R. San Sebastian, D. B. Couch, P. A.
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Riddle, and M. H. Hsie. "Mutagenicity of carcinogens: Study of 101
individual agents and 3 subfractions of a crude synthetic oil in a
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43. Mohn, G. R. and J. Ellenberger. "The use of Escherichia coli
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50
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THE EFFECTS OF H2SO4 ON MEN AND H2SO4
AND O, ON LABORATORY ANIMALS
Donald E. Gardner, Ph.D.
Milan Hazucha, M.D.
John H. Knelson, M.D.
Frederick Miller, Ph.D.
Health Effects Research Laboratory
U.S. Environmental Protection Agency
STUDIES SO FAR
INCONCLUSIVE
HUMAN STUDIES
THREE GROUPS OF
CONCENTRATION
Although sulfuric acid is known to be a strong irritant, the results obtained
through toxicological studies on animals and limited exposure studies on humans
have so far been inconclusive. The greatest problems and uncertainties are in
quantitating the health effects induced by submicron sulfuric acid mist in
concentrations below 100/ig/m^. The assessment of the potential health effects of
sulfuric acid is further complicated by uncertainties as to the extent of the
interaction with various ambient, physical, and physiological factors as well as
chemical agents. Variables such as relative humidity, ambient temperature, level of
breath ammonia, or frequency and depth of breathing, may modify considerably the
response to sulfuric acid and are probably the major causes of the diversity observed
between studies. Because of the inherent problems associated with studying the
effects of pollutants on the human respiratory system, animal model systems have
been developed to investigate various hypotheses that can later, through appropriate
epidemiological surveys, be tested in man. The animal model for the microbe-host
interaction system must be a sensitive one for measuring the subtle effects resulting
from inhalation of toxic substances. The model should therefore reflect a summatidn
of the varied responses of the respiratory tract, which may include edema, cellular
disruption, reduced macrophage function, inflammation, and immunosuppression.
Eighteen healthy, young, nonsmoking male volunteers were studied. Before
being selected for inclusion in the study, all subjects were given a physical
examination, a detailed history was obtained, and a psychological Minnesota
Multiphasic Personality Inventory taken by the investigator physician. Subjects were
carefully questioned to exclude those taking any medications, those with any recent
pulmonary infections, allergies, and so forth. In addition, blood was drawn for
standard blood tests; and temperature, blood pressure, and pulse were recorded
before starting the experiment. Consent was obtained from each subject prior to the
study. Each subject was exposed for three consecutive days to either clean air or
H2S04. On days 1 and 3 each was exposed to clean air and on day 2 to H2S04.
The 2-hour exposure protocol was the same for all 3 days. Since the subjects
alternated 15 minutes of exercise (500 W) with 15 minutes of rest, pulmonary
function tests were done 10 minutes after the end of each exercise during the
resting periods. The environmental conditions in the chamber were continuously
monitored for temperature, relative humidity, aerosol concentration, and particle
size. The temperature was maintained at 74° ± 3°, relative humidity at 46% ± 10%,
peak particle size at 0.075 /^m, and 0.055 mean mass diameter. The aerosol was
generated using the modified fuming sulfuric acid technique developed by Scaringelli
and Rehme. The particle size distribution was monitored by the Electrical Aerosol
Size Analyzer Mod. 3000 (Thermosystems, Inc) and the concentration of acid was
determined by chemical analysis of samples collected on Fluoropore filters (Millipore
Corporation).
Subjects were divided into three groups, depending on the concentration they
were exposed to. Group I consisted of four subjects exposed to 66 ± ng/m^. Group
II had 10 subjects exposed to an average of 100 ± 14 ng/m3 and Group III had 4
51
-------
MOST SENSITIVE
TO H2SO4
subjects exposed to an average of 195 ± 35 /ug/m^. Pulmonary function parameters
between 8 and 18 were measured at various time intervals during the experimental
period.
Group I seemed to be the most sensitive to h^SO/j. However, only 3 out of
18 parameters became significantly changed with H2S04 exposure. The FEV 2
(forced exposure volume at 2 seconds) decreased an average of 190 ml, which was
a 3.3% decrease from the control after 2 hours of exposure. Airway resistance
(RAW; plethysmographic method) increased by 3.5% (figure 1) and the functional
residual capacity (FRC) increased by 470 ml, or a 10.9% increase over control.
* AIR (DAY1)
+ H2SO4 (65MG/M3)
#AIR (DAYS)
1.10
0.00
FIGURE \-Group I
0.50
1.00
TIME (HOURS)
concentration (66 ±vg/m )
1.50
2.00
o 1.62
J/3
O
^ 1 KO
I l.oz
1 i
LU
SISTANC
Ji
N>
£ 1.32
<
5 1-22
3
1 1O
I . I Z
,
j^S=s^___,^^^^^^^
**> I fcj.— *
* AIR (DAY 1)
+ H2S04 (100 (XG/M3)
# AIR (DAY 3)
1 I 1 I
0.00 0.50 1.00 1.50 2.00
TIME (HOURS)
FIGURE 2-Group II H2SO4 concentration (100 ±14
52
-------
INSIGNIFICANT CHANGES
Despite a higher acid'concentration and a larger number of subjects, Group II
showed fewer changes than Group I in lung function. Again, only FEV 2 (0.5%)
and RAW (figure 2) showed statistically significant changes. About half of the
remaining parameters showed some degree of improvement during acid exposure day
when compared with control day.
Group III was exposed to the highest average concentration and showed the
least effect. Not a single test was significantly affected at this concentration. About
two-thirds of all lung function tests showed some degree of improvement over the
control day. Airway resistance was increased significantly after 1 hour of exposure.
In the two previous groups it deviated very little from the air days (figure 3).
Similarly, for other functions, air-day results were not significantly different from
the acid-day data. Moreover, although it is well documented that irritant substances
when inhaled will modify the ventilatory pattern, we were not able to detect any
changes in either respiratory rate or tidal volume (figures 4 and 5).
RESULT CONTRARY TO
EXPECTATIONS
The review of our data indicates that subjects exposed to low concentration of
showed greater changes in various lung function parameters than subjects
exposed to higher concentrations. This is contrary to our expectation—that the
higher acid concentrations should have elicited a greater response. A plausible cause
of such an inverse relationship may be a shift in the size distribution curve to the
right towards larger particles. It is well documented that the relative deposition and
retention of particles in various compartments of the respiratory tract is a function
of particle size and a flow regime. The warm humid air of the airways will certainly
accelerate the growth of particles, and the higher the acid concentration, the greater
the shift will be. Consequently, the most sensitive part of the lung to injury, the
small peripheral airways, will be less compromised by the aerosol because the larger
particles will be deposited in the larger upper airways. As discussed earlier, the
pulmonary function tests showed some degree of impairment; however, the clinical
significance of these changes is unclear. Additional studies using a greater number of
subjects as well as more sensitive and specific tests are needed to give us a clearer
picture of the subtle changes in pulmonary function induced by acid aerosol.
I 1.60
O
CM
1.50
O
LU
O
< 1.40
CO
CO
LU
OC
v 1.30
1.20
<
cc
1.10
0.00
* AIR (DAY 1)
+ H2S04 (195MG/M3)
# AIR (DAY 3)
0.50
1.00
TIME (HOURS)
1.50
2.00
FIGURE
3-Group HI H^SO, concentration (195 ±35
53
-------
18.00
O 15.00
14.00-
13.00 -
12.00
* AIR (DAY 1)
+ H2S04 (195MG/M3)
#AIR (DAY 3)
I I
0.00
30.00
60.00
TIME (WIN)
90.00
120.00
FIGURE 4—Respiratory rate
1.30
0.60
0.00
30.00
60.00
TIME (WIN)
90.00
120.00
FIGURE S-Tidal volume
ANIMAL TOXIOLOGICAL
STUDIES
A number of different experimental approaches have been used to demonstrate
the potential of chemical agents for altering host susceptibility to respiratory
infectious agents. One of the most sensitive methods used by laboratories, including
ours, is called the infectivity model. Briefly, animals are randomly selected for
exposure either to filtered room air or to the test substance. After the cessation of
this exposure, the animals from both chambers are combined into a third chamber
where they are exposed for approximately 15 minutes to an aerosol of viable
microorganisms, Streptococcus pyogenes. Group C. At the termination of this
exposure, some animals from each group are sacrificed, and, using standard
microbiological techniques, the number of inhaled microorganisms is determined. The
54
-------
CILIARY BEATING
FREQUENCY
AEROSOL SAMPLES
OZONE GENERATED
remainder of the animals are returned to clean filtered room air, and the rate of
mortality in the two groups is determined during a 15-day holding period. The
control mortality, which reflects the natural resistance of the host to the infectious
agent, is approximately 15% to 20%.
Assays of ciliary beating frequency were performed following in vivo exposure
of Syrian Golden hamsters. The tracheas were excised asceptically and cut into rings
approximately 1 mm thick and the ciliary beating frequency determined using an
electronic stroboscope.
The acid aerosol was generated by heating concentrated H2SO4 to 120°C and
passing 5 1/min of dry air over the liquid. The resulting droplet-vapor mixture was
passed through heated lines to an impactor to remove the largest particles and then
discharged into a mixing flask where 20 1/min of dry air was added. This mixture
was merged with the air stream supplying the animal exposure chamber at a rate
sufficient to provide approximately one chamber vol/min.
Aerosol samples were collected on 47 mm diameter Fluoropore filters
(Millipore Corporation) and analyzed for strong acid, ammonium ion, and soluble
sulfate ion. The sulfate concentration was 900 Afg/m^ ± 90 SD, with approximately
one-third being associated with ammonium ions. The aerosol had a volume median
diameter of 0.23 /urn ± 2.4 SD (geometric) as determined by an Electrical Aerosol
Analyzer (Thermo-Systems, Incorporated). Temperature (25.8°C ± 0.9 SD) and
relative humidity (38% ± 16 SD) in the chamber were monitored by a thermistor
and dew point hygrometer (EG&G, Incorporated).
Ozone was generated by passing oxygen through a neon-tube silent arc
generator. The resultant effluent was mixed with filtered room air to equal a total
flow rate of 11.4 cu ft/min and conveyed into a stainless steel chamber with a
volume of 11.4 cubic feet exclusive of funnels. Ozone was monitored by the
chemiluminescence method.
55
-------
EXPERIMENTAL RESULTS
EXPERIMENTAL DESIGN
The experimental results can best be described in three different phases. The
first phase of these studies consisted of general range-finding experiments which were
necessary to provide information on what concentration of acid mist alone, without
the infectious challenge, would cause an increase in mortality in mice after a single
3-hour exposure. Mice appeared to be very resistant to the acid aerosol alone. In
these studies, a significant mortality (25-50%) was observed only after exposure to
600 mg/m^ but not exposure to 400 mg/m^. By combining carbon particles (5
mg/m^) to 400 mg/m^ of H2S04, a 17% mortality rate was produced; but, at any
lower concentration of acid, the addition of the carbon did not alter the effect of
the acid alone.
In the initial infectivity studies, the concentration of acid mist tested was 100
mg/m^ for 3 hours before administering the bacterial challenge (Streptococcus
pyogenes, Group C). In this series of experiments, there was no difference in
mortality between the animals exposed to acid aerosol and the control air animals.
Based on these types of studies, it became evident that if the inhalation of
H2SC>4 were to alter the host's defense system against infectious agents, it would
have to through its interaction with some other environmental pollutant or stress.
Thus, the second phase of these experiments was designed to study the effects of
the sequential exposure to (^804 with ozone (03).
The exposure
Female mice (CD-1,
weighing 25 grams
group contained 20
exposure to two of
The total exposure
regimens for the experimental design are presented in figure 6.
COBS^, Charles River Breeding Laboratory, Wilmington, Mass.)
were randomly assigned to various treatment groups, and each
animals. The test groups represent all combinations of sequential
the three following test substances: 63, ^504, and filtered air.
length was 5 hours for each treatment group. All exposures to
S PYOGENES CHALLENGE
I I
12345
TIME, HOURS
TREATMENT GROUPS POOLED FOR ANALYSES IN FIG. 2
FIGURE 6—Exposure regimens
56
-------
FILTERED AIR EXPOSURES
196 Atg O3/m3 (0.1 ppm) were for 3 hours and exposures to 900 jug H2S04/m3
were for 2 hours. Filtered air exposures of sufficient duration were added to
treatment groups (groups B through E, figure 6) to maintain the total test period at
5 hours. Control animals (A) were exposed for 5 hours to only filtered air. After
exposure, the test animals were combined and challenged with a viable aerosol of
Streptococcus pyogenes (C). The animals were again separated into their respective
treatment groups and the incidence of mortality observed over a 15-day period.
Neither pollutant alone (B-E) caused a significant increase in mortality, as
compared with clean air controls (A). Statistical analysis indicated that the two
H2S04 groups (B and C) were not significantly different and were therefore pooled
for subsequent analyses. Likewise, the two 03 groups (D and E) were not different
and were also pooled.
H2S04
19
A
0 2 4 6 8 10 12 14
DIFFERENCE IN MORTALITY (TREATED-CONTRpL), PERCENT
A- NUMBER OF REPLICATE EXPERIMENTS GIVEN NEXTTO
STANDARD ERROR BARS
B- SIGNIFICANTLY DIFFERENT FROM ZERO (p-=.05)
FIGURE 7—Increase in mortality for treatment groups and combined pollutant exposure
test groups.
COMBINED POLLUTANT
EXPOSURES
CILIARY ACTIVITY
Figure 7 shows the increase in mortality for these pooled treatment groups, as
well as for the test groups representing the combined pollutant exposures. In those
studies involving the combined action of the two pollutants, there was a statistically
significant increase (p < 0.05) in respiratory infections in the treated group over
controls (indicated by percent mortality) only when the exposure to the oxidant gas
immediately preceded that of the acid. For this increase, the observed mortality was
equal to the additive effect of the individual pollutants. The two combined exposure
groups were not significantly different. When the data of these groups were pooled,
the resulting mean was still statistically different (p <0.05) from the control mean.
An additional experiment was conducted wherein the concentration of ozone
was 0.1 ppm but the concentration of (^804 was lowered to 500 jug/m3 and the
two pollutants were administered simultaneously for a period of 3 hours. A
statistically significant increase in mortality over control of 7.5% was observed for
this treatment group (figure 8). ^804 alone at this level showed no increase in
mortality.
The effects of in vivo exposure to ozone and (^804 on ciliary activity were
investigated (figure 9). Immediately after a 2-hour exposure to 900 £tg H2S04/m3,
.a significant decrease in ciliary activity from control of approximately 320 beats/min
57
-------
12
11
10
oc
o
0
-------
H2SO4
A
-350-300-250-200-150-100 -50 0 50 100
Dl FFERENCE IN Cl LIARY ACTIVITY (TREATED-CONTROL), BEATS/MINUTES
A- NUMBER OF HAMSTERS.
B- SIGNIFICANTLY DIFFERENT FROM ZERO (P<.05).
FIGURE 9—Effects of exposure to ozone and HJiO, on ciliary activity
1100
1050
1000
5$ 950
00
£ 900
>
u 850
< 800
_ (17)A
o
750
700
650
(15) A
B
1 MG H2S04/M°X2HRS
CONTROL
(15) A
(14) A
24 48
HOURS OF IN VIVO RECOVERY
A - ( ) = NUMBER OF HAMSTERS TESTED
B- SIGNIFICANTLY DIFFERENT FROM
CONTROL (P<.05) USING DUNNETT'S TEST.
FIGURE 10-Persistence of depression in ciliary activity with ^2804 exposure
72
59
-------
was observed. Exposure to 196 jug O3/m3 (0.1 ppm) for 3 hours resulted in no
significant difference from control. Experiments designed to study the sequential
effects of 63 followed by H2SO4 also indicated a significant decrease in ciliary
activity of exposed animals comparable to the decrease observed with exposure to
H2SC>4 alone.
Experiments were also conducted to determine the persistence of depression in
ciliary activity that was observed with exposure to h^SC^. For these studies,
animals were exposed to 1 mg of H2SC>4/m3 for 2 hours and then allowed to
recover in clean air for various lengths of time. The results given in figure 10 show
that, even up to 48 hours after exposure, there is still a significant depression in
ciliary activity, compared with control, which by 72 hours had returned to within
the normal range.
COMBINATION STUDIES Since the atmosphere contains numerous chemicals, combined action studies
are extremely relevant in determining the toxicity of pollution. With individual
pollutant exposures at low levels, slight alterations in the biological response are
likely to occur that are both difficult to interpret and to detect as being statistically
significant. However, combination of sequential exposures at low levels may result in
an additive or synergistic action of the pollutants which may be sufficient to evoke
a significant response. The additive effect observed in this study with exposure to
Og and H2SO4, which alone did not produce an effect, clearly demonstrates the
importance of combination studies in environmental toxicology.
60
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panel
discussion
-------
HEALTH EFFECTS PANEL DISCUSSION
David P. Rail, M.D., Ph.D.
National Institute of Environmental Health Sciences
U.S. Department of Health, Education and Welfare
Norton Nelson, Ph.D.
Institute of Environmental Medicine
New York University Medical Center
Kenneth Bridbord, M.D.
National Institute of Occupational Safety and Health
U.S. Department of Health, Education and Welfare
William W. Burr, Jr., M.D.
Division of Biomedical and Environmental Research
Department of Energy
Roy E. Albert, Ph.D.
Carcinogenic Assessment Group
U.S. Environmental Protection Agency
(Additional comments by presentation speakers Dr.
Waters, Dr. Epler, Dr. Gardner, and Dr. Hazucha.)
63
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DR. RALL: One general question arises from hearing the presentations this morning.
The last two presentations dealt primarily with sulfuric acid, which may be only one
of a number of derivative pollutants from the major originating one, sulfur dioxide.
The effort spent to get some indication of the relative quantitative risk from
inhaling sulfur dioxide, SOX, H2S04, while probably not extensive enough, has
certainly been extensive. Drs. Epler and Waters are dealing with possibly hundreds of
different pollutants. What of the future? To what extent can we look at the myriad
pollutants from some of these complex fuel conversion processes? Can we look at
them one at a time, or must we develop broad screening systems which will deal
with groups of pollutants simultaneously?
DR. NELSON: The presentations were, for this very reason, extremely interesting,
presenting as they did a broad exploration of a wide variety of very diverse
compounds with a new, simple, and extremely attractive procedure; a very
meticulous examination of a restricted set of questions in humans and whole
animals. It seems to me that this is the way in which we will have to proceed.
Although the Ames system is very attractive, it is not going to answer all
questions. There are obviously areas where it will not. The Ames system is, however,
extremely powerful. It is very ingeniously contrived, and it can give us some very
sharp answers. In many instances, we are going to have to fall back on much more
meticulous procedures. Sometimes they are going to have to involve people, as well
as the whole animal. One of the things we have not really thought about
sufficiently, but which we have to think about, is the necessary strategy.
I am really not overwhelmed by the number of serious problems; I am
overwhelmed by the relatively modest number of very serious problems, but I am
not going to be awed into settling for a third-rate approach to these very serious
problems because of the multiplicity of possible nasty compounds in the
environment. We need a strategy right now perhaps as much as we need the hard
science approach to these issues. We need to face the fact that we cannot give equal
attention to everything. We need, therefore, to devise a scientific approach, using the
best science we can assemble. We must isolate the hard questions and focus
attention on them. We must also isolate the very soft questions. Certainly we will
make some mistakes, especially in the screening process. Other techniques, ranging
from structure activity relationships to short-term screening tests, will be needed to
help sort these out. We will have to use the accumulated wisdom of people in the
medical and scientific professions who have lived with these problems to help sort
out the hard questions from the easy ones. We should not depend on any one set
of backup techniques for this sorting process.
The gong I would like to sound right now is the urgency of developing not
one but a battery of strategies to sort out the problems that we need to focus on.
We must attempt to sort out the less consequential issues, issues not necessarily to
be wholly shelved, but those which we can put slightly toward the rear of the
cupboard to be pulled out next month. And we must be prepared to find we have
made some mistakes in these decisions.
DR. BRIDBORD: The area of interactions is particularly important and cannot be
overemphasized. Two good examples not confined to the energy-related area,
although certainly impacting on that area, can be cited from my own personal
experience. One deals with the interaction between asbestos and cigarette smoke.
Exposure of a smoking individual to asbestos results in a risk of lung cancer roughly
90 times as great as that of someone not exposed to asbestos and not smoking.
Another interesting example of the importance of interactions comes from studies
supported by the National Institute for Occupational Safety and Health, studies of
the interaction between a drug, Dilsulfram, commonly used in alcohol control
programs, and exposure to ethylene dibromide, a very important chemical
intermediate, which, incidentally, is a scavenger for lead additives in gasoline. The
combined exposure produced a significant increase in cancer in multiple sites,
including angiosarcoma of the liver, whereas in this particular model system the
single exposures did not result in similar effects. We must keep in mind, therefore,
64
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that the environment is complex. We need to be concerned not only about
combined exposure to multiple chemicals in a single medium, such as air, water, or
food, but also about the complex interactions between chemicals, drugs, alcohol, and
cigarettes. We have barely begun to scratch the surface in our understanding of this
aspect.
I would like to make a special point about the need for concern with the
health and safety of the worker in the design of energy technologies. There has
been appropriate emphasis on environmental effects, both for human health and
ecology, but in this discussion the health and safety problems of the worker have
frequently gotten lost. It is particularly important to note that the workers are
often at greatest risk of exposure to toxic chemicals. I make a special plea to have
the biological scientists speak to the engineers. My undergraduate training, before my
medical training, was in the area of chemical engineering. We have not adequately
sensitized the engineering community to the need to ask certain hard questions
about health and safety in the design of chemical plants and engineering facilities.
Were the engineers sensitive to this need, they would begin to ask the questions and
to develop modifications of engineering design and applicability of control
technologies before facilities became "cast in concrete." I think we can make
substantial progress and perhaps encourage ingenious approaches to basic product
development. I am optimistic that this can happen, but it is important to get that
cross-fertilization between the various study disciplines.
DR. BURR: Communication is improving, at least in the Department of Energy. We
do talk with the engineers. We do talk to the technologists. We are improving this
bridge. As far as strategies are concerned, one presented this morning is the same as
the experimental strategy we are using at DOE in support of the work we are doing
in this area.
Keep in mind that this is not the only approach. We certainly need the
epidemiology. DOE has human health studies, as do other agencies. As an
experimental strategy, we process specific materials, looking at chemical and
biological characterization, preferably using simple biological systems. We then go on
to animal validation as necessary, preferably, again, in short-term animal studies.
Next, we conduct dose-response studies. We then address the problem of
extrapolating the data to the actual species of concern, the human. In general, that
is the experimental strategy we are presently following. It may not be the only one
that we should be following. In view of all the other kinds of approaches, such as
epidemiology, that also go on, I don't think it is.
DR. ALBERT: Perhaps, in the studies of pulmonary airway resistance by Dr.
Hazucha and ciliary function by Dr. Gardner, they may be overlooking the effect
of sulfuric acid on clearance, mucociliary transport. Data emerging now show that,
at the levels Dr. Hazucha used, there is a substantial stimulation of the clearing
mechanism from the bronchial tree without any real effects on airway resistance.
Perhaps Dr. Gardner did not see it because he used a rather high level of sulfuric
acid exposure.
The presentations by Drs. Waters and Epler echo the question about the
practical use of these data in real life. The scheme which is neat, elegant, and well
organized is most useful for a preliminary characterization of where the mutants and
carcinogens might be in the various industrial processes, but it will not help much at
the other end of the spectrum—namely, the risk assessment which leads to the
strategies of regulatory control—other than to identify where the major problems
are. The one thing missing is the kind of work that deals with comparative
magnitudes of effect.
65
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For example, take the case of the diesel exhaust. This is an issue of emerging
importance with respect to conservation of energy because diesel engine automobiles
are more economical, but unlike conventional automobiles, they put out particulates.
One can use the tests to show that these exhaust particles have mutagenic and
carcinogenic properties, but any combustion process would exhibit such properties.
If you burn leaves in your backyard, you are producing carcinogens and mutagens.
The central issue in a risk assessment is the question of how carcinogenic these
materials are in relationship to other things that we encounter. This involves
assessment of the carcinogenic and mutagenic potencies. In terms of carcinogenic
potencies, clearly the mutagenesis assays, although they correlate very nicely with
carcinogenesis, don't correlate when it comes to the quantitative aspect of how
nasty the agent is. In determining what we are going to do about things such as the
carcinogens from diesel exhaust, the issue is, how harmful is the material that is
being studied with respect to other materials that we deal with, such as ordinary
particulates in urban atmospheres or the particulates that come out of coke oven
plants in the steel industry? How bad are these particulates in relation to the
particulates from cigarette smoke, a major form of indoor pollution as well as the
pollution of the users. In actually doing a risk assessment, in formulating regulatory
strategy, one needs to get much closer to the issues that relate to the real life
hazard, and the screening techniques, displayed here this morning, although
exceedingly useful, are but one step in that process. Here one really needs
comparative studies.
DR. WATERS: Perhaps, I did not convey in my presentation that what we are, in
fact, talking about with respect to the utilization of short-term tests is just what is
being suggested—detection. This is the place that the tests can be used best at this
time. At this point they certainly are not quantitative. However, there is
considerable effort going into studies on mutagenic and carcinogenic potency, and
efforts to understand the correlations, or lack of correlations, for large numbers of
compounds. I hope you did not get the impression that the short-term tests alone
are the answer. That is certainly not the case.
DR. EPLER: Our central theme with respect to mutagenicity is a comparative
approach, exactly what is being suggested; moving on from microbial testing into
higher organisms, and then finally, on to the mouse, as close as we can get to man
in the laboratory. That is with respect to the end points of both mutagenesis and
carcinogenesis. The complicating factor is that we are working perhaps for the first
time with these assays with complex mixtures rather than pure compounds. Both
types of assays need to be carried out.
DR. GARDNER: Some very fine work is being done by Dr. Lipman and colleagues
at New York University on clearance mechanisms with H2S04- Also Dr. Gerry Lass
at Davis, California, has been looking at acid alone and acid with ozone and finding
increase in mucus production with it. These all fit together in a total package.
DR. HAZUCHA: Increased mucous production would cause some of the changes we
observed. For example, changes in functional residue of capacity certainly were
caused at least partly by increased production of mucus. It is unfortunate that we
have only three to five laboratories in the nation working on problems with air
pollution. We are just touching the tip of the iceberg. We don't know how healthy
older subjects will react, for example, to various pollutants. We are studying only
18- to 25-year-olds, the young athletes one might say. We don't know how children
will react. And I am not speaking about the diseased population. There is a lot of
work to be done.
66
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questions
o* answers
Dr. John W. Blake
Power Authority of the State of New York
Tom Culley
University of Maryland
Philip S. Tow
Sacramento County Air Pollution Control District
Dr. Krishna P. Misra
Food and Drug Administration
Robert L. Goldberg
Environmental Defense Fund
QUESTION
How will the environmental results discussed
determine the effects on human beings?
RESPONSE: Dr. James L. Epler (Oak Ridge National
Laboratory)
We are beginning to learn how the short-term tests
interrelate. We now realize that no one test is sufficient;
we need a battery of tests. We really don't yet know
how they can be extrapolated to man. We need more
research and development, to look at more compounds
and then extrapolate to whole-animal testing, for both
mutagenesis and carcinogenesis, before we can answer
that question. The general answer is going to have
significant impact in determining the effects on man,
but the scientist must learn much more before decisions
can be made.
QUESTION
What is the lung volume at which you measured
airway resistance (RAW)? RAW does vary with lung
volume. Another way to express it is specific airway
conductance (SCAW).
RESPONSE: Dr. Milan Hazucha (EPA)
I have slides for both functional residual capacity
(FRC) and DGE total gas volume at which airway
resistance was measured, but to save time, I did not
show them. Functional residual capacity increased sig-
67
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nificantly at low concentration, 0.66 micrograms. It also
increased significantly at 100 micrograms, but the
change was considerably less. At 200 micrograms no
changes were observed. So, certainly these two tests are,
as you said, interrelated.
QUESTION
The test animal for teratogenesis studies was a
mouse. Are you planning any primate studies on
teratogenesis? We are all familiar with the thalidomide
problem.
RESPONSE: Dr. Michael D. Waters (EPA)
Yes, it would be necessary to use primates at
higher levels of evaluation. In almost any short-term
test, we will miss chemicals with unique metabolism. It
is essential to proceed by steps, as Dr. Epler indicated,
to gain additional information on a number of com-
pounds to understand these metabolic differences. They
are critical, and we just don't have all the answers.
QUESTION
How do you relate acute exposure experiments
using normal healthy subjects to experiments using sub-
jects with severe respiratory problems?
RESPONSE: Dr. Donald E. Gardner (EPA)
We are now testing H2SO4 and other inhaled
particulate matter, using normal animals, animals with
emphysema, and animals with chronic bronchitis. This is
a very important step.
RESPONSE: Dr. Hazucha
All the subjects were young and healthy and very
well screened. The results were unexpected even to us.
With high concentration, we did not see any effect, and
it is almost impossible to say what effects we will
observe on other subjects or subjects with permanent
disease. Preliminary studies of asthmatics showed little
effect from ozone, for example, although the general
expectation was that asthmatics would react strongly.
QUESTION
We are exposed to pathogens at the same time we
are exposed to pollutants, and we are exposed to ozone
at the same time that we are exposed to su If uric acid.
Why aren't these conditions simulated in your studies
with mice? Why aren't they exposed at the same time
to those combinations?
68
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RESPONSE: Dr. Gardner
We are exposing the animals to a combination of
ozone and acid at the same time, and we are getting a
similar synergistic effect. Our problem comes when we
lower the acid concentration to about 500 micrograms
and ozone to 0.1 parts per million. Because of the
buildup of ammonia of the animals during the 2- or
3-hour exposure, we are no longer getting acid. We get
ammonium sulfate because these are whole-body
exposures. So, we are limited. We will correct this by
first going to head-only exposures.
The sensitivity of the model system is increased if
given bacteria at the same time. In fact, it increases
with ozone. For these studies, the number of strepto-
coccus pyogenes inhaled and deposited in the lung at
zero time is approximately 400.
69
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transport
chapter
.recesses
and ecological effects
-------
CHAPTER CONTENTS
transport processes and ecological effects
REPORT DIM THE INTERNATIONAL SYMPOSIUM ON SULFUR
IN THE ATMOSPHERE
Rudolf B. Husar, Ph.D., Washington University
William E. Wilson, Jr., Ph.D., US EPA
Michael C. MacCracken, Ph.D., University of California __
Ralph M. Perhac, Ph.D., Electric Power Research Institute • 5
MONITORING OF AIR AND WATER QUALITY IN THE WESTERN
REGION
David N. McNelis, Ph.D., US EPA
Rudolf F. Pueschel, Ph.D., U.S. Department of Commerce 95
ECOLOGICAL EFFECTS OF ATMOSPHERIC DEPOSITION
Norman R. Glass, Ph.D., US EPA
Gene E. Likens, Ph.D., Cornell University
Leon S. Dochinger, Ph.D., U.S. Department of Agriculture
ECOLOGICAL EFFECTS OF COAL-FIRED STEAM-ELECTRIC
GENERATING STATIONS
Gary E. Glass, Ph.D., US EPA 121
PANEL DISCUSSION:
Allan Hirsch, Ph.D., U.S. Department of Interior
John M. Neuhold, Ph.D., Utah State University
Stanley Auerbach, Ph.D., Oak Ridge National Laboratory
Herbert C. Jones, III, Ph.D., Tennessee Valley Authority
A. Paul Altshuller, Ph.D., US EPA 153
QUESTIONS & ANSWERS 159
-------
TRANSPORT PROCESSES
AND ECOLOGICAL EFFECTS
REPORT ON THE INTERNATIONAL SYMPOSIUM
ON SULFATES IN THE ATMOSPHERE
Rudolf B. Husar, Ph.D.
Department of Mechanical Engineering
Washington University
William E. Wilson, Jr., Ph.D.
Environmental Science Research Laboratory
U.S. Environmental Protection Agency
Michael C. MacCracken, Ph.D.
Lawrence Livermore Laboratory
University of California
Department of Energy
Ralph M. Perhac, Ph.D.
Physical Factors Program
Electric Power Research Institute
CLOSED LOOP SYSTEM
TOPIC CONTENT
OF SYMPOSIUM
It is envisioned that the energy air pollution relationship is a closed loop
system driven by man's urge to increase his well-being, and eroding some of the
quality of life through the environmental impact of his actions (figure 1).
The increasing economic activity has been met in the past by the combustion
of fossil fuels. The air pollutant emissions from fossil fuel combustion are linked to
ambient concentrations through the atmospheric transmission processes (transport,
transformation, and removal). The potential environmental and health effects are the
consequences of atmospheric concentrations or deposition, while the overall harm
caused by primary or secondary air pollutants is determined by the potential effects
as well as the receptor sensitivity. The loop is closed by the harm of air pollution
eroding some of the well-being or quality of life that has been gained through the
utilization of energy.
As in any chain, the closed loop is only as strong as its weakest link. The
International Symposium on Sulfur in the Atmosphere (ISSA) was organized to
strengthen the link between the sources and receptors of sulfur compounds (figure
2).
Where does all the sulfur go? How long will it reside in the atmosphere and
what happens during the transport? A particular concern today is what fraction of
S02 passes through the environmentally more harmful aerosol phase before removal.
The residence time and the transport distance of sulfur compounds in the
atmosphere are determined by the competing rates of chemical transformations and
dry and wet removal.
For sake of scientific rigor and depth, the symposium was confined to
transport, transformation, and removal processes as well as to the properties and
measurements of sulfur compounds in the atmosphere. Neither the effects nor
control techniques were discussed in detail.
The symposium was co-sponsored by the United Nations Environment
Programme (UNEP), Electric Power Research Institute (EPRI), the Environmental
Protection Agency (Interagency Energy/Environment R&D Program), Department of
75
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WELL
BEING
OR
QUALITY
OF
LIFE
FIGURE 1— The energy-air pollution system
FUEL
CONS.
EMISSIONS
ATMOS.
CONC.
EFFECTS
ISSA
FIGURE 2-The scope of ISSA
76
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SYMPOSIUM PARTICIPANTS
Energy (DOE, formerly ERDA) and the American Meteorological Society, and it was
under the auspices of the Yugoslav Academy of Arts and Sciences.
Some 160 participants from 22 countries, mostly from Europe and North
America, participated in the 7-day symposium, held in Dubrovnik, Yugoslavia,
September 7-14, 1977. Following the presentation of 85 invited and contributed
papers, the participants gathered in smaller workshops to develop a scientific
concensus among the differing viewpoints expressed mainly by the European and
North American participants. The symposium proceedings along with workshop
summaries are now published in the journal ATMOSPHERIC ENVIRONMENT,
Volume 12 (1978), pp 1-796. The book version of the proceedings is also available
from Pergamon Press. What follows is a reflection of the key symposium results.
TRANSFORMATIONS
OF SULFUR DIOXIDE
INDIRECT PHOTOOXIDATION
The current estimate for natural volatile sulfur emissions, such as h^S and
DMS, is about 35 million tons per year (Granat et al 1976). This represents a
downward adjustment from about 60-100 million tons per year of natural emissions
which was estimated in earlier global budgets (Eriksson 1960, Junge 1963, Robinson
and Bobbins 1970, Kellogg 1972, Friend 1973).
Man-made emissions, which are primarily in the form of SO2, account for
about 65 million tons per year as SO2 (or about 65% of the global emissions).
However, the bulk of the man-made emissions are confined to regional hot spots
(covering less than 2% of the global area) over North Central Europe and the
industrialized regions of Northeastern America. In the United States, for instance,
SO2 emission is about 1 pound per capita per day.
Sulfur dioxide, a primary pollutant, undergoes chemical reactions in the
atmosphere that lead to a change in its oxidation state, most commonly to 804.
The change is accompanied by a gas-to-particle conversion process having particulate
sulfur, a secondary pollutant, as an end product.
Evidence is accumulating that the major effects of sulfur oxides (those on
health, terrestrial and aquatic ecosystems, visibility, and weather and climate) are
associated more with the reaction products than with sulfur dioxide itself. For this
reason, an appreciable fraction of current sulfur research is focused on the sulfur
dioxide transformation. The questions of main concern pertain to the mechanism
and rate of conversion, the fraction of sulfur dioxide transformed, and the chemical
and physical properties of the particulate sulfur compounds.
It is currently held that the oxidation of sulfur dioxide in the absence of
interfering compounds is slow compared with the observed or inferred atmospheric
conversion. Hence, one chatlenge of atmospheric chemistry is to determine which
substances and which environmental or emission characteristics promote or inhibit
sulfur dioxide oxidation in the atmosphere.
Four mechanisms are believed to be important in atmospheric sulfur dioxide
conversion. The first, indirect photooxidation, is homogeneous, i.e., the key step in
the sulfur dioxide oxidation occurs in the gas phase. The other three are
heterogeneous, the reactions occur in liquid particles or on particle surfaces. As
noted earlier, direct photooxidation of sulfur dioxide in pure air or sulfur dioxide
oxidation in pure water droplets is believed to be negligibly small (Beilke and
Gravenhorst 1978, Calvert et al 1978, Eggleton and Cox 1978).
Indirect photooxidation is a major route for conversion of sulfur dioxide to
sulfate in the troposphere. The sulfur dioxide is oxidized after gas-phase collision
with strong oxidizing radicals, such as HO, HO2, and CH3O2- One of the sources of
these radicals in the polluted troposphere is hydrocarbon-NOx mixture, which in the
process of daytime photooxidation produces oxidizing radicals as intermediate
products. The sulfur dioxide oxidation step is therefore indirectly linked to
photochemistry. The chemical kinetics of this mechanism have been formulated in
models that use measured rate constants. The modeling results were consistent with
laboratory tests of sulfur dioxide conversion in the presence of photochemically
reacting hydrocarbon-NOx mixtures. An unambiguous confirmation of the
77
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CONVERSION RATE
PERCENT/HR
x
O
CM
O
to
cr
o
0)
.c
-RCHOO, 0(JP),
CH30
30 60
Irradiation Time, min
2 HOURS
90
120
FIGURE ^-Theoretical rate of attack of various free-radical species on sulfur dioxide
(%/hj for a simulated sunlight-irradiated (solar zenith angle, 40°), polluted atmosphere.
Reprinted with permission from Culvert et al.
CHEMICAL KINETICS
SMOG-CHAMBER
MEASUREMENTS
homogeneous conversion mechanism would require the direct observation of the
reactive transients (such as HO, HO2, and CH3O2 radicals) under a variety of
atmospheric conditions. Such data are not available.
Numerical simulations of chemical kinetics for typical urban mixtures (figure
3) indicate 2-4%/hour(h) for a sunny summer day (Calvert et al 1978). Eggleton
and Cox 1978, in a summary of European results, concluded that, in the western
European summer, sulfur dioxide oxidation rates due to gas-phase radical reactions
in sunlight are expected to be between 0.5 and 5%/h, depending on the degree of
pollution of the atmosphere. The lower figure refers to cleaner troposphere. In the
winter, owing to the reduced sunlight intensity and duration, the conversion rates
are expected to be lower by a factor of 2-5 (and perhaps an even greater factor).
Smog-chamber measurements occasionally show higher conversion rates (Miller
1978). It is likely that the homogeneous conversion rate will depend on the absolute
concentration, as well as on the initial ratio of hydrocarbons to NOX.
78
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CATALYTIC SO2 OXIDATION
The specific roles of temperature, dewpoint, and solar radiation intensity on
the indirect photooxidation require systematic study. The current understanding is
sufficient, however, to incorporate gas-phase chemistry into large-scale reactive plume
models.
Catalytic sulfur dioxide oxidation in droplets has been studied extensively, but
the results regarding its role in the atmosphere are less conclusive. The consensus
reached at ISSA Workshop 1 is as follows:
The catalyzed oxidation of S02 in solution by transition metals (e.g., Fe,
Mn) is believed to be important in situations in which relatively high
(>10~5 M) molar concentrations of catalyst are present in the droplet
and in which the total atmospheric concentrations of catalytic elements
are also high. Such conditions can exist in urban areas and in stack
plumes and perhaps in urban fogs. In cleaner rural air, this reaction
would occur only in clouds. However, unless the pH and metal
concentrations are substantially different from those in rain water, this
process is unlikely to be of significance. Both laboratory and field results
of such reactions are necessary.
Oxidation in the liquid phase by strong oxidants has recently been receiving
increasing attention (Beilke and Gravenhorst 1978, Eggleton and Cox 1978). Ozone
and hydrogen peroxide absorbed in liquid droplets can promote the rate of
oxidation to be comparable with or exceed the rate of indirect photooxidation.
However, the current oxidation rate data vary by a factor of around 100; this
prohibits an assessment of its importance in the atmosphere. The ozone and
hydrogen peroxide in polluted atmospheres originate from the gas-phase
photooxidation of hydrocarbon-NOx mixtures. In clouds or fogs, such gases are
absorbed into the water droplets within seconds. Measurements of hydrogen peroxide
in polluted and clean atmospheres are necessary, as well as chamber studies, to
resolve the discrepancy of existing laboratory data.
SURFACE CATALYZED
OXIDATION
Surface-catalyzed oxidation of sulfur dioxide on collision with solid particles
has been demonstrated in the laboratory. Elemental carbon (soot) appears to be
particularly effective in this regard (Novakov et al 1974). However, because the
existing data refer to sulfur dioxide oxidation on filters containing soot, the
importance of this mechanism for suspended catalytic aerosols cannot be assessed.
A common feature of these major sulfur dioxide conversion mechanisms is that
the rate-controlling species can be identified; they may in principle be controlled
independently of sulfur dioxide, and their source is not necessarily that of the sulfur
dioxide. It is regrettable that only the indirect-photooxidation mechanism can now
be expressed in terms of oxidation rates and therefore the relative importance of
these mechanisms cannot be evaluated. A major difficulty in the interpretation of
laboratory liquid-phase reactions is that in the atmosphere that reaction occurs
sporadically (in clouds), rather than continuously.
The burden of establishing the actual conversion mechanisms and rates in the
atmosphere rests with the field experiment. In recent years, a variety of approaches
have been used for this purpose.
LARGE-SCALE
MONITORING AND MODELING
In large-scale monitoring and modeling, an emission inventory over a region and
meteorological (transport) conditions are used as the input data for regional-scale
(about 1,000-km) transport models. The models also incorporate the rates of sulfur
dioxide conversion and removal. The actual rate constants are unknowns, but they
can be extracted from a best-fit comparison between calculated and observed values.
In the Organisation for Economic Co-operation and Development (OECD) 1977
study, the trajectory models were tuned to monitoring data obtained daily at about
70 stations. The measured daily concentration data for sulfur dioxide, SO^Und S6~4~
in precipitation were compared with calculations, and the rate constants for
transformations and dry and wet removal were adjusted until a best fit was
obtained. The key model values for the OECD study are listed in table 1.
79
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TABLE 1
Values applied in the calculations with the Lagrangian Dispersion Model in the OECD Project
Characteristic
Value
Fraction of Emitted Sulfur Deposited
~ Locally
Fraction of Emitted Sulfur Transformed
Directly to Sulfate
Rain
Decay Rate of Sulfur Dioxide
Dry
Transformation Rate S02
Loss Rate of
0.15
0.05
4.10~5/s (14.4%/h)
1.10~5/s (3.6%/h)
3.5'10~6/s (1.26%/h)
4-10-6/s (1.44%/h)
Mixing Height
1,000 m
"Data from OECD.
MAJOR STUDY PROJECTS
The year-round average conversion rate of 1-2%/h and the overall average dry
removal rate of about 3-4%/h were key new results of the OECD study. Studies
similar in scope and objective to the OECD study are being conducted in the United
States. The Sulfate Regional Experiment (SURE) (Perhac 1978) of the Electric
Power Research Institute, the Multistate Atmospheric Power Production Pollutant
Study (MAP3S) (MacCracken 1978) of the Department of Energy, and the Sulfur
Transport and Transformations in the Environment (STATE) study of EPA are
examples. The close coordination of these major projects appears to be highly
desirable and is being pursued by the various project directors.
The main utility of the regional approach is that the obtained rate constants
are inherently averages over all sources and spatial-temporal scales of interest. It is
recognized, however, that the rate constants for removal and transformations are
actually variables that may depend on source configuration, meteorologic conditions,
and the presence of external (nonsulfur) species.
PLUME STUDIES
CONVERSION RATES
The average rate constants can be obtained from the regional monitoring and
modeling efforts, but the specific dependence of the rates on the underlying
chemical and physical processes has to be studied on a smaller scale. The gap
between regional (1,000-km) scale and laboratory simulation can be bridged by
mesoscale studies of sulfur transport, transformations, and removal (transmission).
These are generally referred to as plume studies. Inherently, quantitative single-plume
studies are limited to a spatial scale of less than 500 km and a plume age of less
than 12 h.
The average oxidation rate over the lifetime of sulfur dioxide is about 1-2%/h,
as determined by fitting the rate constants in regional-scale models to European
monitoring data. In plumes of a midwestern power plant, as part of the Midwest
Interstate Sulfur Transformation and Transport Study, (MISTT), the conversion rate
was measured to be 1-4%/h during the daytime and <0.5%/h at night, yielding a
daily average conversion of 1-2%/h during the summer (Husar et al 1978), (figure 4).
Laboratory simulations and chemical kinetic model calculations of gas-phase
controlled sulfur dioxide conversion in the presence of oxidizing radicals also
indicated a 1-2%/h daily average conversion rate for summer conditions. The
contribution of liquid-phase oxidation is not well established, but it is thought to be
important.
80
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A—4
SOLAR RADIATION
'
0 2 4 6 8 10 12 14 16 18 20 22 24
FIGURE 4—Sulfur conversion rate for the Labadie power plant plume for nine sampling
missions. The points to the left of each bar are the release times and to the right the
sampling times.
REMOVAL OF SULFUR
COMPOUNDS
The residence time and the. transport distance of atmospheric sulfur are
determined by the overall removal rate of sulfur compounds from the atmosphere.
Overall removal has four major components: dry removal of sulfur dioxide, wet
removal of sulfur dioxide, dry removal of 804, and wet removal of 804. Dry
removal of sulfur dioxide and wet removal of 804 appear to be the two major
components.
DRY DEPOSITION
Dry removal of sulfur dioxide is a mass-transfer process whereby sulfur dioxide
is first transported to a surface by turbulent and molecular diffusion and then
removed by adsorption or absorption at the surface. The overall mass-transfer rate
can be characterized by a mass-transfer coefficient (v^) and the difference between
the bulk and surface concentrations. Because the unit of v^ is length per time, it is
called deposition velocity. Conceptually, it is also convenient to use the overall
resistance to mass transfer (r = 1/v^), which is the sum of several, largely
independent resistances.
The surface resistance (rs) incorporates adsorption and absorption. In the case
of vegetation, rs is believed to be dominated by the size of the stomatal openings.
The aerodynamic resistance (ra) is due to turbulent diffusion in the atmospheric
surface layer and controls the rate of dry deposition during stable conditions
(inversions) (Garland 1978).
81
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WET DISPOSITION
The range of deposition velocities was summarized at ISSA Workshop 2 and is
shown in tables 2 and 3.
Wet deposition of sulfur compounds proceeds through a combination of
in-cloud and below-cloud scavenging by precipitation (rain and snow). The rate of
wet deposition can be calculated from the sulfur concentration of precipitation and
precipitation rate. Sulfur deposition rates are compiled here for a number of
different areas that vary in climate and industrial activity (table 4).
TABLE 2
Sulfui dioxide deposition velocities over vegetation*f
Vegetation
Height Example Height, m
Short Grass 0.1
Medium Crops 1.0
Tall Forest 10.0
Deposition
(Vd), cm/s
Range
0.1-0.8
0.2-1.5
0.2-2.0
Velocity
Typical
0.5
0.7
Uncertain
*ISSA Workshop 2.
tValues were obtained in a humid climate, much smaller
values are likely in arid climates.
TABLE 3
Sulfui dioxide deposition velocities over soil*
Deposition Velocity
(Vd), cm/s
Acidity (pH)
Calcareous (>7)
Calcareous (>7)
Acid (~4)
Acid (~4)
State
Dry
Wet
Dry
Wet
Range
0.3-1.0
0.3-1.0
0.1-0.5
0.1-0.8
Typical
0.8
0.8
0.4
0.6
"ISSA Workshop 2. No information is available to assess Vd
on desert sand or lateritic soils.
82
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TABLE 4
Representative annual average rates of wet and dry deposition of sulfur*
Location
Heavily In-
dustrialized
Areas
Rural
Remote
North
America
Europe
North
America
Europe
North
Atlantic
Other
Oceans
Continents
Excesst Precipi-
tation Sulfate
Concentration (as
sulfur, mg/l)
3-?
3-20
0.5-2
0.5-3
0.2-0.6
0.04
0.1
Wet Depo-
sition Rate
of Sulfur,
g/m^.yr
O.U-3
2-4
0.1-2
0.2-2
1-3
0.01 $-0.2
O.Oli-0.5
Dry Depo-
sition Rate
of Sulfur,
g/m2.yr
3-15
0.2-2.6
0.5-5.0
0.04-0.4
0.4
* ISSA Workshop 2.
t Excess over concentration due to sea salt.
| Low deposition rates result from low precipitation.
DRY AND WET DEPOSITION
To understand sulfur deposition, rates of both wet and dry deposition must be
measured. On a regional scale, this has been done only by the OECD study in
northern Europe, although a similar study, the Multi-State Atmospheric Power
Production Pollution Study (MAP3S), is currently underway in the United States.
In the OECD study, overall dry and wet removal rates were estimated by
comparing monitoring data with appropriately tuned model calculations. The rate
constants that were extracted from these comparisons are given in table 1. The
study concluded that, of the total emission of 20 Tg of sulfur oxides per year, dry
deposition accounts for 11 Tg, or about 55%, wet deposition accounts for about 6
Tg, or 30%, and the balance is exported out of the study area.
WET VERSUS DRY
Although regional information is lacking for the United States, there have been
intensive investigations on the relative magnitude of wet versus dry deposition for
plumes (Granat and Rodhe 1973), urban areas (Husar et al 1976a), and rural areas
(Likens et al 1978). The results of these, coupled with the results of the OECD
study, indicate that, near sources (stack and urban areas), dry deposition is more
important as a removal mechanism than wet deposition. In areas removed from local
sources, wet deposition is more important. For the purposes of constructing sulfur
budgets for a large area (such as the eastern United States), the rates of wet and
dry deposition of sulfur can be assumed to be roughly comparable.
RESIDENCE TIME
The residence time of sulfur dioxide is determined by the competing rates of
transformations to sulfate and by removal of sulfur dioxide and 804. Using a
conversion rate of 1-2%/h and an overall removal rate of 2-4%/h leads to a
characteristic residence time of 14-33 h or about 1 day for sulfur dioxide. The
residence time of sulfur dioxide in single plumes was estimated from aircraft
sampling data and combined with simple models (figure 5). The residence time of
sulfate is the sum of the formation and removal times. According to the current
estimates (ISSA Workshop 3) the sulfate residence time is 3 to 5 days.
83
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AEROSOL
FIGURE 5—Flow diagram of sulfur transmission through the atmosphere. Over half of the
SO2 is removed or transformed to sulfate during the first day of its atmospheric
residence.
1200
6 8 10 12 14 16 18 20 22 24
TIME OF DAY
FIGURE ^-Schematics of plume geometry at four different parts of the diurnal cycle
TRANSPORT
VERTICAL TRANSPORT
Once the residence times are set, the transport distance and the region of
impact are determined by the mean horizontal wind speed at the height of the
sulfur layer. Wind speeds of 500 km/day are typical for the midwestern United
States. In the MISTT study, for instance, power plant plumes have been identified
and mapped up to the age of 12 hours or transport distance of 300 km (Gillani et
al 1978).
The plume dispersion within the planetary boundary layer is .facilitated by
vertical transport. Due to the increased atmospheric stability at night, narrow
ribbon-like plumes develop isolated from the surface. During the day, these plumes
flood the rising mixing layer and are subject to dry deposition. During the unstable
afternoon hours, plumes frequently mix up to 1-2 km heights, creating pollutant
layers aloft (figure 6).
84
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60
CO
o
ro~"
a.40
Q_
Q
O
O
>20
2 oxidation is the formation of particulate sulfur, which has
been positively identified to be the. sulfate ion (Stevens and Dzubay 1978).
In the case of homogenous or gas phase controlled SC>2 oxidation, the reaction
product, sulfuric acid, either self nucleates or gets deposited onto the existing
aerosol population. The diffusional transfer of gaseous or ultrafine h^SC^ results in
a preferential growth of sulfate aerosol in the size range between 0.1 and 1.0 nm
(figure 7). This size window has been referred to as the accumulation mode (Whitby
1978).
From the symposium deliberations (ISSA Workshop 3), it was concluded that,
at temperate climates in mid-latitudes, about 20-50% of the S02 converts to sulfate
before removal.
Over the eastern United States, sulfates constitute about 30-50% of the aerosol
mass below 2 ;um (Stevens and Dzubay 1978). The sulfate aerosol occurs either as
H2S04 or as its partially or fully neutralized salts (Charlson et al 1978, Brosset
1978). Regrettably, the relative abundance of these sulfur compounds is not known.
The emission rate of S02 for the states in the Ohio River Valley Region is
between 20 and 30 g/m2/year (figure 8).
Contours of yearly average sulfate concentration reveal that the maximum
concentrations occur in the region of high emission density. In the Ohio River
Valley, for instance, the yearly average sulfate concentration exceeds 15 ng/m3 and
85
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FIGURE a-SOj emission contours
10
FIGURE 9— Yearly average sulfate concentrations
DEFINITE SUMMER PEAK
is between 10 and 15 jug/m^ over a large part of the eastern United States (figure
9). The seasonal pattern displays a greater geographical extent of the high sulfate
concentration in the summer than in the winter months (figure 10).
The monthly average sulfate concentration at non-urban sites of the eastern
United States shows a definite summer peak (figure 11), while the seasonal emissions
are almost the same. The seasonal pattern of sulfate in precipitation, obtained by
the MAP3S study, also shows a pronounced summer peak (figure 12).
86
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WINTER
FIGURE 10—Seasonal sulfate concentration patterns
SUMMER
16
12
01
a.
NASN
EPA
MAMJ J
MONTH
A
ON
FIGURE Vt-Monthly average sulfate concentration [vg/m / 1970-1974 for 18 eastern
nonurban sites ( - ). The seasonal pattern at 6 stations in the industrialized northeast
(——) is more pronounced than the seasonal pattern of 12 peripheral stations in the
midwest and southeast (———).
87
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MAP3S
DOE
I I I I
M
A
M
J J
MONTH
A S O N D
FIGURE 12-77ie seasonal pattern of sulfate in precipitation, from MAP3S study
ATMOSPHERIC SULFATE
REGIONAL SCALE
DISTRIBUTION
The atmospheric turbidity obtained by the National Oceanic and Atmospheric
Administration (NOAA) at 26 eastern United States sites is consistent with the
seasonal sulfate pattern (figure 13). The consistency is to be expected, since at least
half of the aerosol light scattering is associated with sulfur compounds (Charlson et
al 1978). It is therefore evident that the amount of sulfate contained in the
atmosphere is by a factor of two or three higher in the summer than in the winter
months. Therefore any S02 reduction scheme during the summer (e.g., solar
augmented energy supply) would yield more than its share in the reduction of
sulfate.
Visibility degradation, which is primarily due to the light scattering by
aerosols, also exhibits a summer peak over the eastern United States (figure 14). The
spatial-temporal dynamics of aerosol-containing air masses during the summer period
can be illustrated by contours of visibility data gathered at the National Weather
Service sites. In figure 15, successive visibility contours illustrate the transport of
hazy air masses.
The regional scale distribution resulting from a variety of sources is being
monitored by large scale programs, such as the Organization for Economic
Co-operation and Development (OECD) (Ottar 1978), Sulfate Regional Experiment
(SURE) (Perhac 1978) of the Electric Power Research Institute (EPRI), and the
88
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J J A S 0 N D
FIGURE 13-The seasonal pattern of turbidity of 26 eastern United States sites
89
-------
6 —
E 4
'o
DAYTON
60 < RH < 70%
i ii i I
I I i i
MAMJJA
MONTH
S O N D
FIGURE 14-The seasonal pattern of visibility at Dayton, Ohio, 1970-1975
; FIGURE 15-Maps of noon visibility over the continental United States between June 25
\ and July 5, 1975. Contours are plotted for extinction coefficients 4, 6, and 8 (x 10
\ m~*), corresponding to visual ranges 6-4 (light shade), 4 (medium), and <3 miles (black).
90
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SURE CLASS I STATION
SURE CLASS II STATION
FIGURE 16-The SURE network
PLUME STUDIES
NUMERICAL MODELING
Multi-State Atmospheric Power Production Pollution Study (MAP3S) (MacCracken
1978). On the other hand, mesoscale or plume studies, such as MISTT and the new
STATE program, elucidate the diurnal pattern and other details of transport,
transformation, and removal processes.
The contribution of the electric utility industry to the total atmospheric
sulfate levels over the Northeastern United States is being investigated by EPRI's
SURE program, which is now operational. The high spatial density (figure 16) and
temporal resolution of this network permits the study of sulfur budget over the
northeast on a scale comparable to the transport distance of sulfur compounds in
the atmosphere (Perhac 1978)'.
The MAP3S program of DOE has focused its attention on improving
capabilities for numerical modeling of regional pollutant patterns. To accomplish
this, a wide range of special studies focusing on precipitation scavenging and
chemistry, transformation and dry removal processes, and measurement of pollutant
concentrations in the boundary layer is underway (MacCracken, 1978).
In Europe the international exchange of sulfur was estimated by export-import
budget models. The OECD program has confirmed that sulfur compounds do travel
long distances (several hundred km or more) in the atmosphere and has shown that
the air quality in any one European country is measurably affected by emissions
from other European countries.
91
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F.R. GERMANY
F.R. GERMANY
OECD
\
OECD
DRY DEPOSITION
WET DEPOSITION
FIGURE 17—OECD maps of dry and wet deposition of sulfur and wet deposition of
sulfur emission from Federal Republic of Germany
MOST BENEFIT-
EMITTING COUNTRY
In the case of Federal Republic of Germany, for example, which is the size of
a midwestern state, about 30% of its own emissions are dry deposited and 5% are
wet deposited within its own boundaries (figure 17). The remaining 65% is deposited
abroad (OECD 1977). The study concludes, nevertheless, that any given country
impacts on itself more than on any other country. Therefore, the emission
reductions will most benefit the emitting country (or state) itself.
In conclusion, it was the general feeling among the participants that the
symposium has contributed to the clarification of the atmospheric portion of the
sulfur budget. There was a general acceptance of the transport across national
boundaries, about the residence times, about the size of sulfate particles and the
homogeneous or gas phase SO2 conversion processes.
TWO LINES OF THOUGHT
The participants also stressed that there is no reason to believe that the
atmospheric part of the sulfur budget differs significantly from North America and
Europe. However, in Europe and Canada scientists have been concerned more with
ecological problems resulting from acid precipitation, whereas in the United States
the driving force has been the health effects. Thus the United States has emphasized
atmospheric concentrations while the Europeans and Canadians have stressed the
sulfur deposition. One of the most valuable aspects of the symposium was the
interaction and merging of the two lines of thought. This enhanced understanding is
due to the international OECD project in Europe and the Interagency
Energy/Environment R&D Program in the United States. A continuing interagency
and international program, including government and industry, is needed to develop
the most appropriate control strategies. In doing so, rules of reason should be
utilized as an alternative to the adversary attitudes between the environmental
groups, the government and industry.
92
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References
Beilke, S. and G. Gravenhorst. Heterogeneous SO2-oxidation in the droplet phase.
Atmos. Environ. 12:231-239, 1978.
Brosset, C. Water-soluble sulphur compounds in aerosols. Atmos. Environ. 12:25-38,
1978.
Calvert, J. G., F Su, J. W. Bottenheim, and O. P. Strausz. Mechanism of the
homogeneous oxidation of sulfur dioxide in the troposphere. Atmos. Environ.
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Charlson, R. J., D. S. Covert, T. V. Larson, and A. P. Waggoner. Chemical
properties of tropospheric sulfur aerosols. Atmos. Environ. 12:39-53, 1978.
Eggleton, A. E. J. and R. A. Cox. Homogeneous oxidation of sulphur compounds in
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SOX/MSC>4 from the U.S. EPA/Teknekron Integrated Technology Assessment of
Electric Utility Energy Systems. ISSA, 1977.
Garland, J. A. Dry and wet removal of sulphur from the atmosphere. Atmos.
Environ. 12:349-362, 1978.
Gillani, N. V., R. B. Husar, J. D. Husar, D. E. Patterson, and W. E. Wilson, Jr.
Project MISTT: Kinetics of paniculate sulfur formation in a power plant plume out
to 300 km. Atmos. Environ. 12:589-598, 1978.
Granat, L. and H. Rodhe. Study of fall-out by precipitation around an oil-fired
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Granat, L., H. Rodhe, and R. 0. Hallberg. The global sulphur cycle. In B. H.
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Husar, R. B., J. D. Husar, N. V. Gillani, S. B. Fuller, W. H. White, J. A. Anderson,
W. M. Vaughan, and W. E. Wilson. Pollutant flow rate measurement in large plumes:
Sulfur budget in power plant and area source plumes in the St. Louis region.
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Preprints of Papers Presented at the 171st National Meeting, New York, N.Y., April
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Husar, R. B., D. E. Patterson, C. D. Paley, and N. V. Gillani. Ozone in hazy air
masses. Paper presented at the International Conference on Photochemical Oxidant
and Its Control, Raleigh, N.C., September 12-17, 1976. 10 pp.
Husar, R. B., D. E. Patterson, J. D. Husar, N. V. Gillani, and W. E. Wilson, Jr.
Sulfur budget of a power plant plume. Atmos. Environ. 12:549-568, 1978.
Junge, C. E. Sulfur in the atmosphere. J. Geophys. Res. 68, 3975-3976, 1963.
Kellog, W. W., R. D. Cadle, E. R. Allen, A. L. Lazrus, and E. A. Martell. The sulfur
cycle. Science 175:587-596, 1972.
Likens, G. E., F. H. Bormann, R. S. Pierce, J. S. Eaton, and N. M. Johnson.
Biogeochemistry of a Forested Ecosystem. New York: Springer-Verlag, 1977. 146
pp.
Lyons, W. A., J. C. Dooley, Jr., and K. T. Whitby. Satellite detection of long-range
pollution transport and sulfate aerosol hazes. Atmos. Environ. 12:621-631, 1978.
MacCracken, M. C. MAP3S: An investigation of atmospheric, energy related
pollutants in the Northeastern United States. Atmos. Environ. 12:649-659, 1978.
Miller, D. F. Precursor effects on SC>2 oxidation. Atmos. Environ. 12:273-280, 1978.
Moore, D. J. and J. P. Lodge, Jr., Eds. Workshop reports, ISSA (International
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Novakov, T., S. G. Chang, and A. B. Harker. Sulfates as pollution particulates:
Catalytic formation on carbon (soot) particles. Science 186:259-261, 1974.
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Ottar, B. An assessment of the OECD study of Long Range Transport of Air
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Perhac, R. M. Sulfate regional experiment in Northeastern United States: The
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Whitby, K. T. The physical characteristics of sulfur aerosols. Atmos Environ.
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MONITORING OF AIR AND WATER QUALITY
IN THE WESTERN REGION
David N. McNeils, Ph.D.
Environmental Monitoring and Support Laboratory
U.S. Environmental Protection Agency
Rudolf F. Pueschel, Ph.D.
National Oceanic and Atmospheric Administration
U.S. Department of Commerce
AIR QUALITY
Concern over the environmental impacts of the energy development activities
in the western United States is apparent in both the executive and legislative
branches of our Government. Policy statements, legislative proposals, and research
mandates are appearing with increased frequency and most relate either directly or
indirectly to the resources existing in the Western Energy Resource Development
Area (WERDA). Historically, the West has been an area with a relatively low
population density and correspondingly low industrial development. Because of these
factors, it contains several so-called pristine areas generally not impacted by
anthropogenic activities. However, general deterioration in the air quality over the
whole region, particularly with respect to visibility over the past several years, is
widely acknowledged. Concern over any additional degradation is reflected in the
enactment ,of the Clean Air Act Amendments of 1977, particularly in Part C, Title I
(Prevention of Significant Deterioration of Air Quality), and Section 169A, Part C
(Visibility Protection for Federal Class I Areas).
WATER QUALITY
Also of concern in the West is the potential impact on water quality and
supply. Water is already in short supply in the semiarid West. The accelerated energy
developments in these areas are in direct competition with other users for the
limited available water resources. The extraction of raw materials, fuel refinement,
transport and utilization, and the accompanying demographic changes will place
additional demands on available water. The water quality stands to be degraded as
both the consumptive and nonconsumptive use increases and as major hydrographic
changes are made as a result of diversion of water to use sites.
This paper describes the status and initial results of a major interagency
program directed at integrating air and water quality research and monitoring data in
95
-------
DATA SITES
the WERDA. Cooperating with the U.S. Environmental Protection Agency, the U.S.
Geological Survey*, and the National Oceanic and Atmospheric Administration in
this program are several other agencies of the federal and state governments.
The status of environmental quality assessment in the WERDA can be
described in precise terms; the results, currently, are far less specific.
When national attention turned to the West as a source of energy in the early
1970's, there was relatively little information available on the water resources of the
major energy area. Deposits of low sulfur, strippable coal, oil shale, and uranium
generally occur in semiarid areas of sparse population, little development, and hence
little prior need for information describing the local water picture, and even less for
data on the quality of the water. In 1973, for example, there were only 78 sites
(figure 1) in the Northern Great Plains coal region where water quality data were
systematically obtained on streams. The sites where groundwater quality was
measured were even fewer in number. Today, the quality of water in streams is
determined at 170 sites in this region (figure 2), and the number of wells where
water quality is periodically measured has also greatly increased. The pattern has
been repeated elsewhere. In 1973, there was water-quality information available at
three sites in or near Colorado's Piceance Basin where several billion barrels of oil
YELLOWSTONE R
MONT
WYO
NORTHERN GREAT
PLAINS COAL FIELD
200 KM
FIGURE -\-Water quality stations, 1974
*The input of Hugh H. Hudson, Water Resources Division, to this report is
particularly acknowledged. .
96
-------
OO 0
YELLOWSTONE R O
NORTHERN GREAT
PLAINS COAL FIELD
200 KM
FIGURE 2-Water quality stations, 1978
BASELINE CONDITIONS
are contained in deposits of shale. Now, 30 sites are operated to determine the
water quality of streams. Streamflow quality was measured at five sites in the coal
and uranium areas of northwestern New Mexico 5 years ago; today, there are 40
sites throughout these energy areas. Observation wells for determining groundwater
quality in the energy areas of New Mexico have increased from near zero to about
35. Fortunately, nearly all of this increased water-quality measuring activity was
achieved prior to large-scale mining and processing of energy resources.
Before we go further into water-quality determination, let us offer some
objectives and definitions of this activity. The objectives are several. Even in its
natural state, water in different areas contains an extremely wide range of chemical
constituents such as major ions and trace elements, as well as numerous organic and
inorganic chemical compounds. In addition, natural waters contain variable
concentrations of suspended sediment and have wide ranging temperature extremes,
degrees of hardness, and often an aquatic biota characteristic to the area. If
departures from its natural state are to be determined, these departures must be
referenced to natural or predevelopment conditions; that is, baseline conditions
against which water-quality changes may be measured. The first order of business is,
therefore, to document the physical, chemical, and biological qualities of Streamflow
and groundwater systems prior to energy development.
97
-------
PARAMETERS CONSIDERED
HIGH QUALITY FLOW
The parameters considered in measuring water quality encompass the total
effects of mining and conversion. Uppermost in many minds is erosion from
surface-mining activities as a measure of the success of reclamation or restoration of
mined lands. Consequently, the sediment concentrations and total sediment loads in
streams affected by mining operations are often measured. The chemical quality of
streamflow, including its concentrations of various salts, is the next most significant
parameter. The compositions of the salts and the concentration of other elements
that affect the utility of the water as a fish or riparian wildlife habitat, or its
compatibility with soils when applied as irrigation water, are therefore measured.
Obviously, those elements as compounds that make drinking water safe have to be
measured. Trace elements that may be introduced into streamflows by mining or
disposal of waste materials from plants that convert coal, oil shale, or other resource
raw material into energy have to be taken into account in comprehensive
water-resource evaluations. Then, there is the additional possibility of water-quality
degradation by the simple impact of the population whose wastes so often find their
way into the natural water systems. Comprehensive monitoring of the quality of
streamflows must include observing and counting the simple to complex organisms
that live in the streams. Several coliform bacteria types provide direct evidence of
human waste contamination. A periodic evaluation of the taxonomic composition of
the benthic invertebrates in a stream reach is a means of determining the biological
health of the stream, as these organisms act as integrators of water quality changes.
Of course, not all of the parameters mentioned above are measured at all sites.
In addition to the introduction into water courses of materials that degrade
water quality, the matter of withdrawing, for various energy-associated uses, the
water of highest quality also affects the overall water resource. In the energy areas
of the West, water quality generally deteriorates as flows progress downriver from
their mountain snowmelt sources. If energy demands call for a removal of the
high-quality headwater flows, then consideration must be given to what happens to
the residual water and its utility for other purposes in the downstream reaches.
These are among the factors that are considered in designing and operating a system
of streamflow-quality measuring sites.
V TOTAL DISSOLVED SOLIDS (MO/11
J CONDUCTIVITY (((mho/cm) |
37°00
; FIGURE 3-Mean total dissolved solids (mg/liter) and conductivity (urn ho/cm} U.S.
\ Geological Survey sampling stations in the San Juan River Basin
98
-------
DETERIORATING WATER
GROUNDWATER QUALITY
One example of deteriorating water quality can be observed in the San Juan
River Basin in the Four Corners Region of Colorado, Utah, Arizona, and New
Mexico (figure 3). Total dissolved solids and conductivity values significantly increase
as the San Juan and its tributary waters proceed toward Lake Powell. The specific
composition of the dissolved solids varies with local geology as well as the flow,
although the same general trend is apparent. A detailed discussion of the
energy-related source contributors as well as a treatment of the implications of the
consumptive and nonconsumptive water use are contained in the Energy Impact
Assessment Report on the San Juan Basin which will be distributed in July 1978.
Based on the materials presented in the report, the following were concluded:
• Surface water availability in the Basin will limit future growth and
development patterns and may impact the development of energy resources.
• Although present water quality is generally good, as availability is reduced
water quality in downstream reaches will become a problem. The water
quality parameters most likely affected by increased development in the
Basin are salinity, toxic substances, suspended sediments, nutrients,
temperature, pH, alkalinity, and flow. Organic pollutants from coal
gasification plants are of special concern due to the lack of available data
regarding both their nature and quantity.
• Secondary development pollution impacts are likely to become the major
contributing problem.
• Mercury levels in fish in the Navajo Reservoir are among the highest in the
Southwest and probably are due to the mercury-bearing sedimentary rock.
A significant contribution of the Assessment Report is a priority classification
of parameters considered effective in monitoring the impact of energy development
in the San Juan Basin. Three priority levels were thus established: (1) those which
must be monitored, (2) those of major interest, and (3) those of minor interest.
The second in this series of Basin reports, also to be published this year,
covers the Tongue and the Powder Rivers in the Northern Great Plains. The Belle
Fourche and the Little Missouri River Basins will be covered in the third report.
Measuring groundwater quality is quite different. In a sense, this job is easier
because sediment is no problem, temperatures remain about the same, biological
problems are generally nonexistent, and changes in chemical quality occur very
slowly. Moreover, the frequency of sampling groundwater can usually be much less
than for streamflows; once or twice a year is usually adequate to detect
water-quality changes. On the other hand, the groundwater monitoring job is more
difficult because new approaches that have no precedent are being considered for
the development and mining of coal and oil shale in the West. Therefore, no
experience is available as to the impacts of these new development approaches on
groundwater quality. Large-scale, oil-shale development, for example, has never been
carried out, making the in situ extraction of oil from shale within the zone of water
saturation an event without precedent. Work continues on the engineering aspects of
in situ gasification of coal, but little is known about the actual quality of water
that reenters the burned-out coal seams and resides there with the elements and
compounds that do not escape with the gas.
URANIUM EFFECTS
Little is being done to determine the effects of uranium mining on
water-resources systems except on a broad, regional basis. Whether the uranium is
extracted by open-pit, shaft, or solution techniques, the primary initial effects, if
any, will likely be on groundwater. There is some evaluation underway to detect
groundwater quality changes in the vicinity of uranium mines, but the results are
not widely disseminated, and the measuring techniques may be inadequate. In the
case of solution mining, for example, quantities of fluid injected and withdrawn may
be accounted for, and the perimeter of the mine may be measured by sampling
from observation wells; but if the groundwater flow system is not well understood,
its flux may mask losses of injection fluid to groundwater moving through the mine
99
-------
ASSESSMENT RESULTS
A CASE HISTORY
area. There is also the potential impact from surface water runoff over spent tailing
piles.
Results of water-resources assessments of Western energy areas have, thus far,
not been particularly revealing. The reason, in the case of oil shale, is simple: there
has been no commercial or even prototype development.
With coal, development has not progressed rapidly. Mining has increased, but
no gasification or liquefaction plants have been built. Several thermalelectric plants
have been or are being built, and their wastes are being measured and evaluated.
One such plant, now under construction near Gillette, Wyoming, will utilize both
wet and dry cooling to conserve water. Its cooling water will be treated sewage
effluent from a nearby town, a progressive and perhaps ultimate goal in water
conservation.
One of the few case histories of water-quality degradation associated with
Western coal mining is in North Dakota. Sulfate-laden water is observed migrating
downward and laterally from an abandoned water-filled mine pit. The sulfate
presumably originated in gypsum that was exposed in the process of mining
leonardite. The plume of sulfate now extends more than a mile from the mine and
contains up to 6,500 milligrams per liter of sulfate. This mine began operating in
1960, and thus it is unlikely that present-day mining and reclamation practices
would permit the recurrence of conditions that led to this problem. Nevertheless,
the water-related aspects of other coal-mining operations are being observed and
studied. Typically, water produced by mine dewatering is minimal, and its quality
100
-------
WATER-QUALITY MONITORING
presents no particular problem. A mine in Montana produced about 0.03 cubic
meters per second and is allowed to flow into the Tongue River. Overall, its quality
is better than that of the river.
Water-quality monitoring in energy regions of the West is being performed
largely by federal and state agencies with some local monitoring by coal companies
or their consultants. The monitoring activities by industry are, as would be
expected, around their developments. There is little doubt that the intensity of
water-quality measuring sites will increase as new mines open, the requirements of
the Surface Mining and Reclamation Act of 1977 go into effect, and new conversion
plants are constructed.
The intensification in monitoring activities has also occurred with respect to air
quality in the West. Table 1 shows the number of sulfate-nitrate monitoring stations
in Western Energy Resource Development Area (WERDA) by state that were active
in 1975 and those either on or expected to be on line this year. The real
TABLE 1
Number of stations (WERDA)
AZ
CO
MT
NM
ND
SD
UT
WY
TOTALS:
Sulfate
1975
56
3
4
1
30
2
5
3
104
1978 *
47
34
15
7
37
7
19
18
184
Nitrate
1975
19
2
4
1
30
2
5
3
66
1978 *
17
34
15
7
37
7
19
18
154
PROJECTED
MONITORING STATIONS
TYPICAL VALUES
significance in the increase can be seen in the States of Colorado, Montana, Utah,
and Wyoming where only a few stations were operating. Figure 4 shows the total
suspended particulate stations. The solid dots show the sulfate-nitrate stations
operational during 1976. Again the lack of coverage in the four states is apparent.
Figure 5 shows how the newly activated stations are distributed and how the gaps
are filled in the areas where energy activities are expected to be at the highest level.
Areas with intensified coverage include Mercer County, North Dakota, where by
1986 an approximate 3 gigawatts of electric power will be added; Campbell County,
Wyoming, where approximately 25% of western coal will be mined; and the oil shale
areas of the Green River Formation and the areas around the Navajo, San Juan and
Four Corners Facilities where by 1986 over 5.5 gigawatts of electric power will be
generated.
Figure 6 shows some typical values encountered, in this case, in the State of
Arizona for the first quarter of FY 77. The concentration values for the uninhabited
regions in the North are generally low (1-3 jug/m3) while in the South-in the
vicinity of Phoenix and Tucson where several smelters are in operation—the values
are much higher.
101
-------
AIR QUALITY BASELINE
AIRCRAFT DATA
Another approach to establishing an air quality baseline for this whole area
and to studying trends is through the use of airborne monitoring platforms. This
becomes increasingly important when the objective is assessing other than local
impacts. The long-range transport and transformation studies need data on the
3-dimensional distribution of pollutants. Figure 7 shows a typical plume flight over
the Navajo power plant in Northern Arizona. Spirals are performed to determine the
vertical plume centerline and then downwind and crosswind passes are made to
determine the concentrations of the various pollutant components in the plume. The
same types of measurements are made over the large areas as shown in figure 8.
This is a typical mission up through the Central Utah power corridor.
Aircraft participating in these types of missions generally carry a broad
spectrum of monitoring instrumentation (table 2). In addition to the criteria
pollutants (with the exception of carbon monoxide), visibility, condensation nuclei,
particle-size distribution, and meteorological data are collected. Wind speed and
direction can be calculated from the aircraft position and vectoring data.
O HIVOL - TSP
• HIVOL - TSP
SULFATE, NITRATE
FIGURE ^-Paniculate sampling in WERDA, 1976
102
-------
TABLE 2
Instruments installed in the wide area monitoring aircraft
Parameter
Visibility
(Scattering)
Nitric Oxide
Ozone
Sulfur Dioxide
Temperature
Dewpoint
Altitude
(Pressure)
Position
Hydrocarbons
Condensation
Nuclei
Particulate Size
Distribution
1 nstru ment/Method
Integrating
Nephelometer
Chemi luminescent
Chemiluminescent
Pulsed Fluorescence
DME/VOR
Automatic
Cloud Chamber
Two Stage Impactor
And Final Filter
Typical Operating
Range
BScat °-10 x 10'4m"1
0-50 PPB
0-500 PPB
0-1000 PPB
0-500 PPB
-50°C to +50°C
300 107 particle/cm3
Stage 1 Greater Than
3.6 Aim
Minimum Detectable
Concentration
.2 x 10-4m-1
1 PPB
5 PPB
8 PPB
2 PPB
Accurate To Within
.1 NM
Stage 2 Greater Than
0.65 /urn
After Filter Greater Than 0.1 /im
TRACE ELEMENT
ANALYSIS
A modified Sierra cascade/impactor is used to collect the aerosol data in three
size fractions as shown at the bottom of the table. These fractions are subsequently
subjected to trace element analyses which yield results as shown on table 3 for the
wide area monitoring flights through Arizona and Utah. Note that for these missions
the observed concentrations are very low and, assuming the accuracy of the cutoffs,
that most of the activity for sulfur is associated with particles between 0.65 and 3.6
/urn, while for silica most of the activity is associated with particles between 0.1 and
0.65 jum in diameter.
Other characterizations of aerosol particulates over several different
geographical and geologic regions are also being conducted to provide clues as to the
origin and the formation mechanism of the particles. Scanning electron microscopy
and X-ray energy dispersive analyses are applied to materials collected on Nucleopore
filters for these studies.
AEROSOL PARAMETERS
In particular, aerosol parameters that are being observed and their potential
effects investigated are as follows:
Particle size which helps to determine the effectiveness of an aerosol to
scatter light and to nucleate cloud drops.
Particle shape which indicates the mechanism by which the aerosol has been
formed. Sphere are almost exclusively formed by a mechanism that includes
a phase transition.
103
-------
FIGURE 5—New sulfate-nitrate monitoring sites
TABLE 3
Trace element analysis
Element
AL
SI
S
CL
K
CA
Tl
FE
P
Concentration (/ug/m^ )
0.2
0.2
0.05
1.5
0.1
0.02
0.02
0.04
0.06
0.4
10
0.2
3
1
0.2
0.08
0.2
0.2
Stage
(Most Mass)
1
3
2
3
3
1 & 2
1 & 2
1 & 2
1 & 2 ONLY
104
-------
ARIZONA
•3 -2
•2 -2
•2
•2
•5
19 2
5"'-4'.3
'3
•1
•2
'12
'12
•7
.[11,10]
•7
FIGURE 6-First quarter 1977 sulfate (iJ.g/m3)
'5 '7 -[9,5]
HUNTINGTON
CANYONn
EMERYn
1MOHAVE
FIGURE 7-Typical plume flight
105
-------
HUNTINGTON
SAN „
JUAN
a
FOUR
CORNERS
REID
GARDNER
a
nHARRY
ALLE
LAS
VEGAS
FIGURE 8— Typical wide area monitoring flight
FIGURE 9-Four Comers power plant plume
106
-------
FOUR CORNERS, NM.
30 July 1975
0728-0735 MOT
14 miles Downwind
FIGURE 10-Aerosol characteristics of the Four Corners power plant plume
FIGURE 11-Co/sw/p power plant plume
107
-------
Elemental composition of the particles which provides information on (1)
the portion of the aerosol that is mineral-derived, based on a comparison of
the ratio of the elements in the particle to that in the earth's curst; (2) the
enrichment in the atmospheric aerosol of certain elements, e.g., lead sulfur,
chlorine, in relation to the earth's crust; (3) the portion of the atmospheric
aerosol that is composed of elements lighter than sodium due to the
inability of the detector to measure the X-rays of these elements, and (4)
the portion of the atmospheric aerosol that is made up of ammonium
sulfate as the ammonium ion is not detectable.
AEROSOL INFORMATION
Examples of the types of information that can be gained from application of
the method to different types of aerosols are shown in the next few figures. Figure
9 shows the visual appearance of the plume from the Four Corners Power Plant
near Farmington, New Mexico, to a distance of about 13 kilometers. Figure 10
shows the aerosol characterization of a sample that was collected 22 kilometers
downwind from the stacks. Shown are the percentage of particles by number that
exhibit the properties shown for the diameter ranges 0.1 to 0.5 /urn and 0.5 to 1.0
It follows from this information that:
SULFUR CONCENTRATION
• All of the plume particles are spheres.
• All of the particles contain silicon.
• Aluminum, iron, and calcium dominate in the larger aerosol range size.
• Sulfur dominates in the smaller aerosol size range and all of the sulfur is
associated with siliceous types of materials.
This suggests that ammonium sulfates are virtually not detectable in this plume at
this particular distance from the stacks. A more thorough analysis of the sulfur
concentration as a function of particle diameter shows that sulfur is deposited on
the surface of the siliceous flyash aerosol.
COLSTRIP, NIT.
09 Sept, 1977
1312-1332 MDT
24 km Downwind
loo-
«
O
c
's 60-
FIGURE 12-Aerosol characteristics of Colstrip power plant plume
108
-------
COLSTRIP PLUME
A NATIONAL GOAL
AEROSOL CHARACTERISTICS
CEDAR MOUNTAIN
More recently constructed power plants with more efficient participate (flyash)
emission controls have significantly different characteristics of the plume aerosol.,A
portion of the Colstrip, Montana, power plant plume is shown in figure 11. It can
be seen that the plume appears invisible even at a short distance from the stacks.
The aerosol characteristics of a sample collected at 22 km downwind from the
Colstrip stacks are shown on figure 12. While the aerosol is still dominated by
spheres, their number concentration is smaller than for the Four Corners Power
Plant plume. Chemically, they consist of about equal parts of siliceous materials and
non-emitting species, or particles without response. A small portion of the aerosol
consists of mineral-type particles and particles that emit only sulfur.
The particulate characterization data which I have been discussing were only
for particles in the 0.1 to 1 /urn decade of diameter. These are the particles which
are the most efficient at causing visibility degradation. Section 128 of the Clean Air
Act Amendments of 1977, PL 95-95, declared as a national goal the prevention of
visibility impairment from manmade air pollution and the restoration of natural
visibility in federally designated Class I areas. In the section on Prevention of
Significant Deterioration, the Amendments also specify allowable increments for
Total Suspended Particulates (TSP) and sulfur dioxide increases. It appears, however,
that it may not be technically possible or practical to use these increments for
achieving the required optical air quality. It is necessary, therefore, to describe both
a measurement scheme and a standard for visibility based on objective criteria. For
these reasons and to establish a visibility baseline for the western region, visibility
research and monitoring have been initiated.
Figure 13 shows one of the vistas from Cedar Mountain in east-central Utah
which eventually will be affected by local energy development activities. Figure 14
shows the aerosol characteristics that were found for that site in December 1976, on
a day when the average visibility was 193 km. It can be seen that the aerosol is
again dominated by spherical particles, particularly in the size range from 0.1 /urn to
0.5 jum. Between 30% and 50% of the particles contain sulfur, depending on the
size range. Approximately 30% of the particles show sulfur only, which is typical of
ammonium sulfate particles. The mineral-type particles amount to about 20%.
Approximately 60% of the smaller particles don't show X-ray emissions and are
made up of ammonium nitrates and/or organic matter.
FIGURE "\3-Vista to the south from Cedar Mountain, Utah
109
-------
100-
S! 80-
"o
I
•S 60-
1 ,
20-
CEDAR MOUNTAIN, UT.
03 Dec. 1976
1148-1348 MST
NalMglAlISi I Cl K I Ca TMCrlFe Ba
Particle Properties
FIGURE 14—Aerosol characteristics (193 km visibility)
100-
CEDAR MOUNTAIN, UT.
04 May 1977
1229-1431 MDT
NalMg Al i P I S I Cl
Particle Properties
FIGURE IB-Aerosol characteristics (95 km visibility)
110
-------
SILICEOUS AEROSOL
INCREASE
VISIBILITY MEASUREMENTS
May 3, 1977, was a day on which the average daily visibility was only 95 km.
The aerosol characteristics that were found on a sample collected on this day are
shown on figure 15. Compared to the information on figure 14, it is noted that the
portion of the sulfur aerosol, which almost unequivocally, based on Eastern data, is
held responsible for environmental degradation, has not increased within the
optically important size range from 0.1 to 1.0 /urn diameter. Increased, however, is
the siliceous portion of the aerosol, which is also reflected in the increase of the
mineral-type particles. There is also a noticeable increase in the non-emitting portion
of the aerosol.
The visibility measurements made at Cedar Mountain were based on a
photographic technique, i.e., photographing a distant mountain range against the
horizon sky. A measurement of the contrast ratio of the film densities of the target
and the sky is then used to calculate visual range. Figure 16 shows the results of
visibility measurements made at a research station located at Canyonlands National
Park which is to the south and east of Cedar Mountain. These data are from an
integrating nephelometer and are based on light scattered from the particulates. It is
a point rather than a long path measurement, but again shows the consistent long
visual ranges typical in this area of the West, which over this period of
measurements, were generally over 170 km.
Correlations between these types of light scattering measurements and several
other classes of visibility monitoring techniques will be conducted at the
Canyonlands Station. Transmissometers, telephotometers, and cameras will also be
used, and measurements of wind speed and direction, particle size distributions and
trace element analyses will also be performed.
300
250
- 20°
150
100
-MAX POSSIBLE VISIBILITY (RAYLEIGH SCATTERING)
V
20 WIND
10 SPEED
-I 0 M/SEC
-SEA LEVEL
-360°w,Nb
180° DIRECTION
0
4/16 4/18 4/20 4/22 4/24 4/26 4/28
DATE
4/30
75
65
55
45
TEMP. 0°
©RAIN
FIGURE \Q-Visibility-Canyonlands National Park, Utah
11
-------
INITIAL SYSTEM
ESTABLISHED
Finally, an initial system of seven visibility monitoring stations is currently
being established in the Four Corners Region of Utah, Arizona, New Mexico and
Colorado. This area was chosen because of its unusually good visibility, its grand
vistas and its expected rapid growth in energy resource development activities.
Multiwavelength contrast telephotometers, which measure the brightness of distant
objects and their background sky, will be sited at National Parks as shown as circles
on figure 17. The second group of seven stations noted as squares will result from
an agreement between the EPA and the National Park Service currently being
finalized.
SUMMATION
In summation, only the status of environmental quality assessment in the
Western Energy Resource Development Area can be described in precise terms. The
objectives of the research and monitoring programs, however, are highly specific, and
the results are beginning to provide significant baseline data and clues as to the
mechanisms and cause-effect relationships associated with energy-related pollution.
UTAH-
N.M.
CEDAR
BREAKS
O
DINOSAUR
N.M.
N.P.
CANYONLANDS
o o
CAPITAL REEF
N.P.
BRYCE CANYON
N.P.
BNAVAJO
N.P.
GRAND CANYON N'M'
O
D
SUNSET CRATER
N.M.
ARIZONA
COLORADO
MESA VERDE
O N.P.
N.M.
CHACO CANYON
DBANDELIER
N.M.
NEW MEXICO
N.M.
WHITE SANDS
D
-N.P.H
CARLSBAD CAVERNS
VISIBILITY STATIONS
LEGEND
OEPA
D NPS
FIGURE M-Visibility monitoring network
112
-------
THE ECOLOGICAL EFFECTS OF ATMOSPHERIC DEPOSITION
Norman R. Glass, Ph.D.
Environmental Research Laboratory
U.S. Environmental Protection Laboratory
Gene E. Likens, Ph.D.
Langmuir Laboratory
Cornell University
Leon S. Dochinger, Ph.D.
Forest Service
U.S. Department of Agriculture
ECOLOGICAL EFFECTS
OF ATMOSPHERIC DEPOSITION
The United States National Energy Plan calls for an increased use of
combustion of fossil fuels for the indefinite future. This will cause an increase in
atmospheric emissions of some or all of the precursors of acid precipitation even if
best available control technology (BACT) is implemented on new sources and old
sources are retrofit with BACT. This is due to the conversion of natural gas and,
perhaps, fuel oil installations to coal. Because of the long distance transport
phenomena and associated atmospheric chemical transformations of acid deposition
precursors, the use of very tall stacks will probably not ameliorate the deposition of
acidic substances at great distances (on the order of 100 km or more downwind)
from major sources.
EAST AND WEST
U.S. AFFECTED
Although the problem of acidic atmospheric deposition is largely an eastern
United States problem, there is increasing evidence that parts of the west and
southwest may also be impacted.
Precipitation in much of the west is lower in acidity than in the east. Local
deposition of acid substance may neutralize excess alkalinity in some western soils.
Long-distance transport and deposition, however, will increase deposition of acid
substances in both the eastern and western states.
In the western United States there is increasing evidence that acidic
precipitation exists both in the vicinity of major point sources and in and near large
urban areas. In Pasadena, California, measured values of pH in rainfall during
portions of 1976 and 1977 show a range of 2.7 to 5.4 with a weighted mean value
of 3.9 (Morgan pers. comm.). This is a pattern of acidity that is commonplace in
113
-------
SULFUR AND NITROGEN
REMOVAL
DRY AND WET
DEPOSITION
the eastern United States. In the San Francisco region, pH of rainfall has frequently
been measured (McColl, Likens, pers. comm.), and the indication is that it is below
the CC>2 equilibrium value of 5.7. McColl's data show that 80 percent of the
samples taken have a measured pH of less than 5.2 with a range of 4.8 to 5.6 and
a mean pH of 4.9. Acidic precipitation likewise has been measured in the
Seattle-Tacoma area at distances from the major SC>2 sources at the Tacoma Smelter
and nearby refineries.
Sulfur and nitrogen compounds are removed from the atmosphere by two
processes: a) dry deposition including the absorption of gases on exposed surfaces
and the sedimentation and impaction of particulates and b) wet deposition in which
sulfur and nitrogen compounds are frequently deposited as acids. Acidity of
precipitation should be understood as a reflection not only of the amounts of
sulfuric, nitric, hydrochloric, and organic acids in the atmosphere, but also of the
balance between all the cations and anions dissolved in precipitation. Some of these
ions are beneficial mineral nutrients; others are injurious to plants and animals.
Dry deposition is a continuous process depending mainly on the concentration
of sulfur oxides near the ground, the yearly amounts deposited generally decreasing
with increasing distance from the source. Wet deposition is much more variable and
is dependent both on the pattern of precipitation and on the burden of sulfur and
nitrogen compounds within the mixing layer. Deposition can be substantial in areas
exposed to precipitation from air which has passed large emission sources. In cold
climates, air pollutants deposited during the winter may accumulate in the snow
pack. When snow melts, much of the pollutant load is released in concentrated form
with the first melt water. This release may lead to sudden increases of acidity in
watercourses and also to some extent in the soil.
Recent reviews of available data (1, 2, 3, 6) indicate that precipitation in a
large region of the United States is highly acidic when compared with the expected
pH value of 5.7 for pure rainwater (5,9). Figure 1 shows that the average pH of
precipitation in the northwestern United States was routinely less than 4.7 in the
mid-1960's. It has been further shown, by the change in the position of pH
isopleths between 1955-56 and 1972-73 (figure 2), that acid precipitation has spread
southward and westward in the United States (1,6). More recent information
indicates that in this area, pH values between 3.0 and 4.0 are observed during
individual storms (3).
FIGURE 1-Predicted pH of precipitation, 1965-1966, Cogbill and Likens (1974)
114
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AVERAGE PH OF ANNUAL PRECIPITATION
1955-56
FIGURE 2-Time source of change in pH of precipitation from 1955-1956 to 1972-1973
in the northeastern United States, Likens (1976)
Although the historical record on changes in acidity of precipitation is sparse,
there are definite indications that precipitation in the eastern United States was
already acid by 1955 and that the acidity of rain and snow there increased
significantly sometime between 1930 and 1950 (6).
DAMAGE
FROM ACID RAIN
A growing body of evidence suggests that acid rain is responsible for
substantial adverse effects on the public welfare. Such effects include acidification of
lakes, rivers, and groundwaters, with resultant damage to fish and other components
of aquatic ecosystems; acidification and demineralization of soils; reduction of forest
productivity; damage to crops; and deterioration of manmade materials (7,12,27).
These effects may be cumulative or result from peak acidity episodes (8).
NORTHWEST EUROPE
AFFECTED
A similar drop in the pH of precipitation has been observed in Scandinavia
(9,27,28). A network showed that since the mid-1950's, precipitation in
northwestern Europe had increased in acidity and that this acidity was currently
more widespread geographically. The hydrogen-ion concentration of precipitation in
some parts of Scandinavia has increased more than 200-fold during the past two
decades (10). Data from New York State and New England indicate that about 60
to 70 percent of the acidity is due to sulfuric acid, 30 percent to 40 percent is due
to nitric acid, and that the relative importance of nitric acid has increased during
the last 10 years. These strong acids are thought to stem primarily from gaseous,
manmade pollutants such as sulfur dioxide and nitrogen oxides produced primarily
by the combustion of fossil fuels. Hydrochloric acid predominates in local acid rain
events in Florida which originate from exhaust byproducts from space launches
(11,12).
EMISSION SOURCES
Emission sources for sulfur dioxide and nitrogen oxides are widely distributed
within and outside of urban centers. Contributions can come from both lower and
115
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URBAN PLUME CONTENT
higher height stacks and from near ground level sources. Sulfates including acid
sulfates are present in the stack gases associated with coal-fired and oil-fired sources.
The amounts of sulfuric acid and other sulfates found in plumes can be sufficient to
effect plume opacity and fallout of acid particles near the source. In plumes from
elevated sources, lack of contact with the ground tends to preserve precursors for
some distance downwind. Especially at night and in the early morning hours,
ground-based inversions can isolate the plume aloft so near-source deposition is
minimized (13).
The urban plume already contains the organics sulfur dioxide and nitrogen
oxide, precursors to sulfates and nitrates (14). Photochemical atmospheric reactions
can form sulfates and nitrates relatively rapidly as the urban plume progresses
downwind. However, during periods of effective photochemical activity urban plumes
will tend to be well mixed to the ground. Therefore, dry deposition processes are
competing with atmospheric reactions as sinks for the sulfur dioxide and nitrogen
dioxide (13). At the present time, it is generally considered that in this country,
acid precipitation is most severe in the northeast. However, there is some evidence
for impact in the western United States, at least in major urban areas such as Los
Angeles, San Francisco, and Seattle. Further, recent data show the geographic extent
of the problem to be increasing in the southeast, with all states east of the
Mississippi affected to some degree (6).
Freshwater bodies in many areas of eastern North America and northern
Europe, which today lie in and adjacent to the areas where precipitation is most
acid, are threatened by the continued deposition and further expansion of acid
precipitation. Many of these bodies of freshwater occur in regions underlaid by
carbonate-poor granitic rock, and are poorly buffered and vulnerable to acid inputs
(15). A major number of the lakes in Scandinavia fall within this category. The
acidification of thousands of lakes and rivers in southern Norway and Sweden during
the past two decades has resulted in the decline of various species of fish,
particularly trout and salmon (16,27). The fish populations in rivers and lakes in 20
percent of the area of southern Norway have been affected by increasing acidity
(11,27).
FISH DECLINE
Similar effects have been observed in the Adirondack Mountains in New York.
A recent survey found that 51 percent of mountain lakes have pH values below 5.0;
90 percent of these lakes contain no fish. In contrast, during the period 1927-37,
only 4 percent of these lakes had a pH under 5.0 or were devoid of fish (11).
Other evidence indicates that not only are fish affected by acidification, but
that a variety of other aquatic organisms in the food web are adversely altered
(16,17,18,27). In general, algal communities in lakes with pH under 6.0 contain
fewer species, with a shift toward more acid-tolerant forms. In particular, the
Chlorophyceae (green algae) are reduced in acid lakes (10,27). Some acid lakes and
streams contain greater amounts of benthic moss (Sphagnum) and attached algae,
and the growth of rooted plants is reduced (12,18,19). There is a tendency toward
fewer species of aquatic invertebrates both in the water column and in sediments in
acid lakes and streams (10). The rate of decomposition of organic matter is reduced,
with bacteria becoming less dominant relative to fungi. Swedish workers have
observed thick fungal felts over large areas of sediments in some acidified lakes.
They concluded that decreased decomposition of organic matter on the bottom of
lakes, coupled with greater abundance of submerged mosses and fungal mats, reduces
nutrient cycling from the sediments. This in turn leads to depletion of nutrients and
reduced productivity in acid lakes (11,20).
LAKE-WATER CHEMISTRY
Acid precipitation also causes other changes in lake-water chemistry as well
(21,27). Elevated concentration of aluminum, manganese, zinc, cadmium, lead,
copper, and nickel have frequently been observed in acidified lakes (22). The
abnormally high concentrations are apparently due in part to direct deposition with
precipitation as well as increased release (solubility) from the sediments in acidified
lakes (23). These metals may represent a major phvsiological stress for various
aquatic organisms (11,22,24).
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ACID PRECIPITATION
DAMAGE
MATERIALS
In recent years, concern has been expressed that forest growth appears to have
been affected far away from emission sources. The rate of forest growth declined in
southern Scandinavia and in the northeastern United States between 1950 and 1970,
but it is not possible to state unequivocally that this decline is caused by acid
precipitation (25).
Terrestrial ecosystems are very complex, with numerous living and non-living
components. Since acid precipitation is only one of many environmental stresses, its
impact may enhance, be enhanced by, or be overwhelmed by other factors. Recent
experiments indicate that acid precipitation can damage foliage; accelerate cuticular
erosion; alter responses to associated pathogens, symbionts, and saprophytes; affect
the germination of conifer and hardwood seeds and the establishment of seedlings;
affect the availability of nitrogen in the soil; decrease soil respiration; and increase
leaching of nutrient ions from the soil (25).
Although many of these factors might be expected to adversely affect tree
growth, it has not yet been possible to demonstrate unambiguously decreased tree
growth in the field. However, it is possible that acid damage might have been partly
offset by the nutrient input gained from nitrogen or sulfur compounds commonly
occurring in acid precipitation. Changes already detected in soil processes and soil
nutrient status may as yet be too small to affect plant growth.
Forests are complex. It has been shown that the nature of throughfall (rainfall
reaching the forest floor after passing through the crown canopy) and stemflow
(rainfall reaching the forest floor by draining down the trunks of trees) is affected
differently by different tree species. Thus the composition of precipitation reaching
soil, possibly affecting soil processes and transfers to freshwater systems, could be
influenced by the nature of the tree cover (11,12,25,26).
The deposition of acidic species may cause effects not only to natural
ecosystems, but to manmade materials as well. Such damage to metals, paints,
statuary, and other objects can affect the quality of life as well as result in
substantial replacement costs. Sulfur oxides, nitrogen oxides, and particulate matter
emitted by coal-burning facilities are known to damage materials (7,11,13).
117
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References
1. Cogbill, C.V., and G.E. Likens. 1974. Acid precipitation in the northeastern
United States. Water Resources Research 10:1133-1137.
2. Nisbet, I. 1975. Sulfates and acidity in precipitation: Their relationship to
emissions and regional transport of sulfur oxides. In: Commission on Natural
Resources, National Academy of Sciences, National Academy of Engineering,
National Research Council, "Air Quality and Stationary Source Emission
Control," prepared for the Committee on Public Works, U.S. Senate.
3. Likens, G.E., and F.H. Borman. 1974. Acid rain: a serious regional
environmental problem. Science 184:1176-1179.
4. Newman, L. 1975. Acidity in rainwater: has an explanation been presented?
Science 188:957-958.
5. Galloway, J.N., G.E. Likens, and E.S. Edgerton. 1976. Acid precipitation in
the northeastern United States: pH and acidity. Science 194:722-724.
6. Likens, G.E. 1976. Acid precipitation. Chemical and Engineering News 54 (22
Nov):29-44.
7. Preston, R. and B. Sanyal. 1956. Atmospheric corrosion by nuclei. Journal
Applied Chemistry 6:28.
8. Berry, M.A. and J.D. Buchman. 1977. Developing regulatory programs for the
control of acid precipitation. Water, Air, and Soil Pollution 8:95-103.
9. Barett, E., and G. Brodin. 1955. The acidity of Scandanavian precipitation.
Tellus 7:251-257.
10. Aimer, B. 1974. Effects of acidification on Swedish lakes. Ambio 3:30-36.
11. Glass, N.R. (ed.). Environmental effects of increased coal utilization: ecological
effects of gaseous emissions from coal combustion. U.S.E.P.A. Ecological
Research Series (in preparation).
12. Dochinger, L.S., and T.A. Seliga (eds.). 1976. Proceedings of the first
international symposium on acid precipitation and the forest ecosystem. USDA
Forest Service General Technical Report NE 23. Northeastern Forest
Experiment Station, Upper Darby, Pa.
118
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13. Altschuller, A.P. (Personal communication).
14. Fennelly, P.P. 1976. The origin and influence of airborne particulates.
American Scientist 64:46-46.
15. Galloway, J.N., and E.B. Cowling. 1978. The effects of acid precipitation on
aquatic and terrestrial ecosystems: a proposed precipitation chemistry network.
Journal Air Pollution Control Association 28(3):229-233.
16. Hendry, G.R., and R.F. Wright. 1975. Acid precipitation in Norway: effects on
aquatic fauna. Journal Great Lakes Research 2(Supplement 1) : 192-207.
17. Groterund, O. 1972. Zooplankton and fish in relation to acid melt water and
anaerobic deep water in a lake. Vatten 28:329-332.
18. Hendry, G.R., et al. 1976. Acid precipitation: some hydrobiological changes.
Ambio 5:225-227.
19. Hultberg, H., and 0. Grahn. 1975. Effects of acid precipitation on
macrophytes in oligotrophic Swedish lakes. Journal Great Lakes Research 2
(Supplement 0:208-221.
20. Grahn, 0., H. Hultberg, and O. Landner. 1974. Oligotrophication a self
accelerating process in lakes subjected to excessive supply of acid substances.
Ambio 3:93-94.
21. Gorham, E. 1961. Factors influencing supply of major ions to inland waters
with special reference to the atmosphere. Geological Society of America
Bulletin 72:795-840.
22. Arthur, J.W., and E.N. Leonard. 1970. Effects of copper on Gammams
pseudolimnaeus, Physa Integra, Campeloma decisum in soft water. Journal of
the Fisheries Research Board of Canada 27:1277-1283.
23. Beamish, R.J. 1974. Loss of fish populations from unexploited remote lakes in
Ontario, Canada as a consequence of atmospheric fallout of acid. Water
Research 8:85-95.
24. Biesinger, K.E., and G.M. Christensen. 1972. Effects of various metals on
survival, growth, reproduction, and metabolism of Daphnia magna. Journal of
the Fisheries Research Board of Canada 29:1691-1700.
25. Tamm, C.O. 1976. Acid precipitation: biological effects in soil and on forest
vegetation. Ambio 5:235-238.
26. Jonsson, B., and R. Sundberg. 1972. Has the acidification by atmospheric
pollution caused a growth reduction in Swedish forests? A comparison of
growth between regions with different soil properties. Rapport No. 20, Dept.
of Forest Yield Research, Royal College of Forestry, S-10405 Stockholm,
Sweden.
27. Braekke, F.H. 1976. Impact of acid precipitation of forest and freshwater
ecosystems in Norway. Research Report No. 6. Acid Precipitation on Forests
and Fish. Aas, Norway. 111p.
28. Oden, Svante. 1976. The acidity problem-an outline of concepts. Proceedings
of the Int. Symposium on Acid Precipitation and the Forest Ecosystem (1st).
119
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ECOLOGICAL EFFECTS OF COAL-FIRED
STEAM-ELECTRIC GENERATING STATIONS
Gary E. Glass, Ph.D.
Environmental Research Laboratory
U.S. Environmental Protection Agency
UNDERSTANDING EFFECTS
COLUMBIA STUDY
President Carter's National Energy Plan, presented to Congress in the fall of
1977, recommended an 80-percent increase in the use of coal for electricity
generation. If implemented, such an increase will lead to the construction of many
more coal-fired generating facilities to meet forecasted higher demands for electricity.
Thus, a complete understanding of the effects of such facilities on their surroundings
is critical to the agencies responsible for planning these facilities. The research
program developed by EPA to meet this need in determining the ecological impacts
of increased fossil-fuel utilization is in the third year of a 5-year plan. A holistic
approach was taken in the design of the program and projects were funded in three
major areas: mining, transportation and storage, and combustion of coal. Work in
each of these areas has progressed to the point where there is a need to integrate
and generalize the findings and to translate the information into a form that can be
used by the appropriate agencies.
In the area of coal combustion, a multidisciplinary research project based at the
University of Wisconsin has contributed significantly to meeting these needs. The
research, at the Columbia Coal-Fired Generating Station near Portage, Wisconsin, has
been funded by the Wisconsin Power & Light Co., Madison Gas & Electric, the
Wisconsin Public Service Corporation, Wisconsin Public Service Commission, and the
U.S. Environmental Protection Agency. Since 1970 this study has been monitoring
the effects a particular generating station in one location has on the environment
before construction, during construction, and after operation has begun. Equally
important, this integrated research program has tested methods of impact assessment
that can serve as models for research at other sites. Thirty-one technical reports will
summarize results of all the research, and will include as a part of the final product
a definitive evaluation of siting problems for facilities in other locations. A list of
these reports is given in the bibliography, items 1-31, with their expected
completion date.
In 1969, several Wisconsin electric power companies applied to the Wisconsin
Public Service Commission for permission to construct a 527-megawatt coal burning
power plant in east central Wisconsin. At the time, information on the
environmental impacts of generating stations was practically non-existent.
121
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NEED FOR INFORMATION
IMPACTS-
EXTRAORDINARILY COMPLEX
The need for such information led Professor Dan Willard and associates at the
Institute for Environmental Studies of the University of Wisconsin, Madison, to
propose a study to measure the impact of the proposed power plant. Their goal was
to assess the effect of the plant on all aspects of the environment—water, wildlife,
plants, air, and aesthetics. With support from three utility companies-Wisconsin
Power and Light Company, Madison Gas and Electric Company, and the Wisconsin
Public Service Corporation-they began studies of the site characteristics before
construction was started. These studies were continued during the construction and
early operation of the plant from January 1971 until July 1975.
In July 1975, the Environmental Research Laboratory, Duluth, recognized the
unique research opportunity that existed at the site and the national importance of
the findings and awarded the investigators a 3-year grant (R803971) to continue and
expand the research. The project is now at the close of its third year and currently
involves over 100 persons in 24 research areas.
Evidence so far is that the impacts are extraordinarily complex. They range
from an increase in waterfowl in the degraded sedge meadow (15) and small
increases in air pollutants (3,5) to significant shifts in land use patterns-agricultural
to residential (31).
TABLE 1
Organization of the Columbia coal-fired generating station study
I. Studies of Chemical Constituents and Their Fates
1. Chemical Related Studies
(a) Aquatic Chemistry
(b) Trace Elements
(c) Plume Chemistry and Isotope Tracers
(d) Hazardous Chemicals in Fish
2. Chemical Transport Mechanisms
(a) Air Pollution Modeling
(b) Meteorology
(c) Hydrogeology
(d) Water Use Analysis
3. Synthesis
(a) Mass Flow and Balance of Water, Air, and Chemicals
II. Assessment of Biological Effects of Project Integration
1. Aquatic Systems
(a) Aquatic Invertebrates
(b) Fish
(c) Assessment of a Cooling Lake Ecosystem
(d) Wetland Ecology
(e) Remote Sensing
2. Terrestrial Systems
(a) Plant Damage
(b) Visual Changes
III. Integration of All Components
1. Data Center
2. Assessment and Synthesis of Impact
3. Administration
IV. Siting Criteria
122
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TWO AREAS OF STUDY
To bring coherence to a study made up of so many subprojects, often
overlapping in subject areas, required careful organization and reorganization by
university researchers and close attention by the EPA Project Officer, G. E. Glass.
The research design that evolved in 1977 consisted of two major areas of study
(table 1): 1) studies of chemical constituents and their fates and 2) assessment of
biological effects. An additional area, siting criteria, addressed broader implications
of the results.
Within the area of chemical studies, one group of investigators has worked on
identifying and measuring the chemicals that result from the combustion of coal,
whereas others investigated the means by which these chemicals are transported
after combustion. In addition, a synthesis group has used systems modeling to
describe the major flows and balances of water, air, and chemicals through the
system.
The studies assessing biological effects were further subdivided into aquatic and
terrestrial systems (table 1). The study group, Assessment and Synthesis, has used
special techniques to integrate the data from all biological studies.
SEPARATE SUBPROGRAM
ON SITING
A separate subprogram on siting criteria was designed to incorporate results
from all of the site studies into a generalized step-by-step method for assessing
available energy options and procedures on how to select the best site that would
be applicable in any location.
This report is a cursory review of some of the findings to date with examples
of the methods being used and the implications of the answers for future
construction of coal-fired generating stations.
Burning coal to produce electricity releases chemicals into the air, soil, and
water around a generating station. Thus the studies of chemical components included
a multitude of organic and inorganic compounds; their constituents and fates cover a
broad range of air, land, and water environments. The Columbia plant unit one (527
MW) burns about 5,000 tons per day of low-sulfur, pulverized coal from Colstrip,
Montana, with a typical ash content of 7 to 8 percent. The high energy electrostatic
precipitators installed to reduce particulate emissions collect approximately 98
percent of this flyash residue and discharge it into an ash pond adjacent to the
plant. Smaller particulate matter is released into the air. The gaseous combustion
compounds are discharged into the atmosphere through a 500 foot stack. Figure 1
shows a photograph and diagram of the plant, ash basin, cooling lake, and proximity
of the Wisconsin River.
Construction of the first unit began in 1971 utilizing an artificial lake for
cooling water. The cooling lake was filled in 1974 and the first power generation
began in late 1975. Before the first plant was complete, however, the utilities
announced plans for a second unit on the same site, doubling the size of the
facility. The Wisconsin DNR required that the stack for the second unit be 650 feet
in height. In addition, cooling towers were required to accommodate the summer
discharge of waste heat from the second unit so that the cooling water intake
temperature was below 40° C. The water level of the cooling lake is maintained by
pumping freshwater in from the Wisconsin River.
ASH PIT DRAIN
From the coal handling and storage area east of the cooling lake (figure 1),
coal enters the plant and is burned. Ash is washed and trucked from the ash
hoppers (using some water from the cooling water flow) and enters the ash basin as
a slurry. Water entering the ash basin flows through a series of lagoons that allow
the ash to settle out; the water is then pumped down the ash pit drain and
combines with the water of Rocky Run Creek. Since this creek supports desirable
aquatic life including trout and other game species during the spawning season, the
effects of the ash pit drain on water quality and aquatic life of the stream are being
studied (10,11).
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PUMPING
STATION
ASH
DRAIN
SUB-STATION
GENERATING
STATION
COAL HANDLING
II
COAL STORAGE
(1,200,000 tons)
ASH BASIN//SECONDAR
(70 acres) //SETTLING
SETTLING
BASIN
N. KNOLL
FIGURE l-Photograph and diagram of the Columbia Generating Station located near
Portage, Wisconsin
MOVEMENT OF CHEMICAL
COMPONENTS
In order to trace the flow of potential pollutants through the facility, the
movement of water must be traced through the system. As the replenishment water
from the Wisconsin River moves into the cooling lake and through the power plant,
some of it is taken out to transport ash into the ash basin. Also, the materials from
coal combustion and plant operations which do not end up as emissions from the
stack move with this water into the ash basin. In figure 2, the water concentrations
of some of the principal constituents (e.g., iron, aluminum, copper, chromium, and
cadmium) change as water moves through the generating station (1,3).
Concentrations in the ash delta, where most of the ash settles, show that there has
not been enough time for chemical equilibrium to form in the slurry. By the time
the ash and water reach the first settling basin, most of the concentrations have
risen markedly. Other constituents of the water also have been shown to increase
from input to discharge, such as sulfate, 12 to 180; calcium, 30 to 70; chloride, 5
to 10; all in mg/liter. Peak concentrations of these materials occur in the second
settling basin. It is from this basin that the ash basin drainage water is pumped into
the ash basin drain.
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APRIL 1977
1.5
Fe mg/1 1.0
0.5
1.5
Al mg/1 1.0
0.5
Cu mg/1 0.50
Cr mg/1 0.50
.003
Cd mg/1 .002
.001
WISC. COOLING ASH 1st
RIVER POND DELTA BASIN
2nd DISCHARGE
BASIN
FIGURE 2—Soluble metal concentrations at various stations on the Columbia Generating
Station
ASH BASIN CHEMISTRY
NEW SOLID PHASES
The chemistry of the ash basin is exceedingly complex and has been studied in
detail (1,3). Figure 3 shows scanning electron micrographs of flyash and ash basin
solids and weathering products; bars indicate size in units of micrometers. Figure 3A
shows typical flyash spherical morphology and examples of hollow flyash grains.
Magnification is 1,000 times. Figure 3B shows a large flyash grain coated with
abundant small grains of flyash and condensed phases. The surface material is readily
removed by water and is reactive. Figure 3C shows crystals of sodium sulfate,
IMa2S04, in the form thenardite as a condensed phase inside a hollow grain of
flyash. These crystals are common in fresh flyash from the Columbia Generating
Station and are the source of soluble sulfate in the ash basin drain (3). Figure 3D
shows a smaller flyash grain with surface coatings. In the ash basin weathering or
leaching of flyash initially produces small pits, indicating selective dissolution of
components; (figure 3E, magnification 4,500 times). Other grains of flyash weather
by spallation of surface rinds, producing small flakes of material (3).
New solid phases are formed in the ash basin as this aqueous system
approaches equilibrium. Figure 3F shows an example of cancrinite,
Na3Ca[CO3
-------
FIGURE 3—Scanning electron micrographs of flyash and ash basin solids from the
Columbia Generating Station. Bars indicate scale in units of micrometers. A, an example
showing typical flyash spherical morphology and hollow flyash grains; B, a large flyash
grain coated with small grains and condensed phases; C, crystals of thenardite, Na2SO^,
condensed as a solid phase inside a hollow grain of fresh flyash; D, a small flyash grain
showing surface coatings (32); E, a weathered flyash grain showing pits where selective
leaching has occurred; F, an example of cancrinite, a mineral formed by weathering of
flyash.
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HIGH PH LEVEL
DEGRADATION OF BEIMTHIC
COMMUNITY
The metal oxides which compose the major reactive portions of the ash cause
the pH of the water to rise to 10-11 units. Since standards in Wisconsin prohibit
the release of water at a pH above eight, sulfuric acid is added to the ash basin
drain to bring the pH down. This addition of acid causes the precipitation of
barium and aluminum components. The resultant flock coats the bottom of the ash
basin drain and produces a suspended solids addition to Rocky Run Creek. However,
by the same standards, the ash basin drainage is of better water quality than some
of the surface water running off Wisconsin agricultural lands.
The flock of this complex mixture of aluminum and barium has accumulated
all the way down into Rocky Run Creek, and although it may not be toxic in its
own right, it is not a suitable habitat for benthic organisms to feed and grow in. As
a result, there has been a slow degradation of the benthic community for the
fishery downstream.
Table 2 lists the concentrations of metals in the ash basin in comparison to
laboratory derived water quality criteria, which if exceeded, may become toxic to
aquatic life (24). The levels of these six elements are a cause for continued concern
and evaluation. Chromium has been shown to bioaccumulate in the aquatic
organisms of the ash basin drain but no substantial evidence has yet emerged
indicating toxicity (10,11).
TABLE 2
Comparison of ash basin metal concentrations with water quality criteria
Element
Al
As
B
Cd
Cr
Cu
Concentration in Excess
Possibly Toxic to Aquatic Life
Milligrams per liter
0.1
0.5
0.22
0.0001
0.1
0.01
Range Observed
in Ash Basin
Milligrams per
Liter
0.02-52.6
0.006-0.216
0.1-6.4
0.0001-0.004
0.066-0.142
0.01-0.028
MASS FLOW OF METALS
CONTINUOUS MONITORING
REQUIRED
The mass flow of these elements through the ash basin is obtained by
multiplying the flow of water by the concentrations in the water. Unfortunately,
this is not a trivial calculation because of the complex pathways, volumes, and
uncertainties inherent in the actual operation of a 527-MW steam-electric power
plant. There is some loss into the groundwater under the ash pit, and therefore
further flow of some soluble portions out of the ash basin. Table 3 shows the
annual quantities of the various elements which come into the Columbia Generating
Station in the coal and flow into the ash basin and out the stack. For example, of
the 678 kg of arsenic, 554 kg go into the ash basin; and of the 145 kg of
cadmium, 54 kg enter the ash basin; whereas of the 28 kg of mercury only a trace
enters the ash basin because it is volatized and leaves via the stack. About
two-thirds of the zinc is left in the ash basin.
At the present time, such information exists for 40 elements and work is
being completed on an additional 25. One of the most difficult aspects to this
approach is caused by the variation over the year in coal composition. Although the
coal comes from one source, the variability of the minor and trace components is
not uniform enough for computations of total mass balance over periods of an
entire year. Continuous monitoring is required for accurate computations.
127
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TABLE 3
Partitioning of selected annual elemental flows at the Columbia Generating Station during 1975*
Element
As
Cd
Cr
Cu
Fe
Hg
Mn
Na
Se
Th
Zn
Flow Into CGS
(kg)
678 ± 39
145 ± 53
5,920 ± 660
5,460 ± 200
465,000 ± 15,100
27.6 ± 2.6
57,500 ± 790
98,700 ± 2,600
494 ± 46
2,170 ± 70
5,030 ± 70
Total Flow
Into Ashpit
(kg)
554 ± 43
54 ± 8
2,250 ± 129
3,460 ± 43
Essent. all
Trace
47,200 ± 431
Essent. all
145 ± 9
1,220 ± 43
2,920 ± 137
Flow-Out Stack
(kg)
120 ± 60
91 + 54
3,670 ± 670
2,000 ± 200
Trace
Essentially all
10,300 ± 900
Trace
349 ± 47
950 ± 80
2,110 ± 150
Partitioning rates of stack test of September 5, 1975, assumed to be valid for
all of 1975. Inflow rates from a 1974 analysis of Colstrip coal.
Overrunning Warm Air-
Temperature increasing with
height (south-southwesterly
winds)
Shear Zone
(fluctuating
Temp, and wind)
Cool
(Westerly winds
Trapped Plume
(observed as a flat ribbon
of smoke far into the
north-northeast horizon)
I-
8 km •
Columbia
Generating
Station
1
Schematic of the frontal system, 20 January 1976 PM
360° N
APRIL 23, 1975
• DIVERGENCE
o DIRECTION (MESSER 32 meters)
Ou N
2400 0400 0800 1200
TIME (CST)
1600
2000
FIGURE 4-Measured. and observed plume divergence (23 April 1975) and frontal surface
schematic (20 January 1976 p.m.) at the Columbia Generating Station study area 2
128
-------
STUDY OF PLUME FLOW
SULFUR DIOXIDE MONITORING
In examining the movement of components out of the stack, the transport
medium is in a gaseous state and requires knowledge of the meteorology of the
conditions around the stack to determine transport and deposition. Detailed
meteorological studies have been made in a complete network around the stack (6).
Analysis of this data gives fairly accurate reflections of conditions where the plume
exists, rather than of ground level where a low inversion can cause a change in wind
direction near the ground. A complete study of the plume flow is necessary in order
to compute the mass balance and deposition of gaseous and particulate emissions.
As an example of the complexity of air dispersal in relation to monitoring,
figure 4 shows a period of about 7 or 8 hours and gives the angle of divergence
between wind speeds in the vicinity of the plant, and wind speeds at the top of the
adjacent hill. The dots are the angle of divergence and the squares show wind
direction at the top of the hill. If measurements were made at a ground station,
there could be as much as 100 degrees of difference in wind direction compared to
a station at the stack height.
One of the major gaseous components of interest is sulfur dioxide. Sulfur
dioxide monitoring data has been collected for a series of locations, in all directions
from the stack. These results, in a before and after form, are summarized in table 4.
A complicating aspect in the monitoring of sulfur dioxide concentrations is that it
takes place against a variable background. The background, even in this area, was
not uniform because communities in the region generated plumes that were just as
recognizable as the power plant plume itself. A community of 200 people in the
wintertime generates a reasonably well-defined sulfur plume that moves across the
landscape. The city of Madison, which if 40 miles away, also generates a plume, and
these have to be recognized and taken out of the background data before sulfur
dioxide comparisons can be made (24).
TABLE 4
Distribution of hourly ambient SC>2 concentrations at all monitoring sites before and after
operation of the Columbia Generating Station
Concentrations
Greater Than
jug/m^
10
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
Percentage Time
Before Columbia
Operation (1973-1975)
12.9
6.75
2.03
0.701
0.340
0.166
0.0908
0.0545
0.0333
0.0227
0.0136
0.0121
0.0076
0.0045
0.0015
0.0000
Exceeded
After Columbia
Operation (1976)
15.0
9.17
3.75
1.717
0.856
0.501
0.3056
0.1756
0.1131
0.0692
0.0422
0.0270
0.0220
0.0135
0.0084
0.0068
129
-------
PREDICTED AND OBSERVED
SO2 COMPARED
This large data set also has been used to compare the predicted concentrations
in the plume from the standard plume model with observed concentrations and their
frequencies (figure 5) (5). Point by point comparisons of some of the low
concentrations that are fairly frequent, compared with the predicted values, indicate
that the modeled values are off by a factor of 2 part of the time. If these data are
plotted in a different form, they show that for some of the stability conditions that
are handled in plume models, there is really little forecasting capability for accurate
plume concentrations. There are eight atmospheric stability classifications (33), or
eight types of atmospheric conditions, two of which give reasonably good results
when comparing observed sulfur concentrations with the predicted, and six ,do not.
This suggests that further meteorological studies are required to determine what
characteristics of atmospheric instabilities are causing the plume concentration to
diverge so markedly from what is predicted.
o
2
111
D
a
LU
CC
CALCULATED
20
10
0
- /
/ 1
/
7
f 1
0
1 >
/
OBSERVED
i i i '
20 40 60
\
V
>v.
^"^
i i i """"' """i^— -fcl""~"°""""™"T™~"~"™l
80 100 120 140 160 180 2(
SO2 CONCENTRATIONS (/jg/m3)
FIGURE 5—Frequency of occurrence comparison of the calculated (standard plume
model) and observed hourly concentrations of sulfur dioxide
S02 GROUND-LEVEL CONCENTRATION DOWNWIND
00
E
1
O
t-
(T
h-
LU
CJ
CN
O
CO
140
120
100
80
60
40
20
T | i \ -i | i | r^
DATE - 4-14-76
TIME - 1:30
DISTANCE - 3.9 KM
CLOUD COVER - 6/10
WIND SPEED - 15 M/S
WIND DIRECTION - SOUTH
200 400 600 800 1000 1200 1400 1600 1800 2000
METERS
FIGURE 6—Sulfur dioxide concentrations measured at ground level during plume
touch-down; a 2,000 meter cross-section shown 3.9 km from the stack
130
-------
SULFUR DISPERSION
FROM PLUME
In order to define the dispersion and deposition of pollutants from the plume,
field measurements were made in the area by locating the plume on the ground, and
then running cross sections through it (5). Figure 6 shows sulfur dioxide
concentrations in a 2,000 meter cross section of the plume at ground level taken at
3.9 km from the stack. High concentrations, up to 140 micrograms per cubic meter
(^g/m3), were measured in the center of the plume, with a tailing off on both sides.
This indicates that the plume spreads out when contacting the ground, but that
there is still a central core to the plume where sulfur dioxide remains at relatively
high concentrations. This information is required to determine the dose received in
the fumigation of crops, trees, and people living in the area.
The reaction and deposition of reactive gaseous components of the plume at
the air-earth interface has been measured and the data for various plume touchdown
conditions are shown in figure 7. Data of these kind are being used to develop and
validate deposition models for air pollutants.
0.6
0.0
-1.0
-2.0
-3.0
SO
WIND
Grass (damp)
0 1.0 2.0 3.0
WIND SPEED (m/s)
30 40 50 60
S09 CONCENTRATION (,ug/m3)
1.0
0.0
•o
N
"c-1.0
-2.0
-3.0
WIND
Field (snow covered)
0 1.02.03.04.05.06.07.08.0
WIND SPEED (m/s)
100 120 140 160 180
0.6 •
0.0
[-1.0
-2.0
-3.0
Soil (moist)
0 1.0 2.0 3.0
WIND SPEED (m/s)
50 60 70
S02 CONCENTRATION (|ug/m3)
0.0
•g-1.0
-2.0
-3.0-
WIND
Wetland prairie .
0 1.0 2.0 3.0 4.0 5.0 6.0
WIND SPEED (m/s)
40 45 50 55 60 65 70
SO2 CONCENTRATION (ng/m3) S02 CONCENTRATION (/ug/m3)
FIGURE 7—Measured concentration profiles of sulfur dioxide in the plume of Columbia
Generating Station over grass, soil, snow, and prairie. Ln(z-d) is the log of the height
above the aerodynamic displacement height, d.
131
-------
TABLE 5
The flux of flyash into the environment as measured by the content of flyash in the material
collected in a fallout bucket. Each collection period was about 30 days ending on the date
shown for a site 3.9 km east of the Columbia Generating Station.
Collection
Date
Before Operation
11-17-74
12-14-74
01-13-75
02-11-75 '
03-13-75
04-14-75
After Operation
05-12-75
07-07-75
08-05-75
09-05-75
1 0-06-75
10-24-75
11-21-75
12-19-75
01-23-76
Flux of Flyash
mg/m^/Day
—
0.62
—
0.47
0.32
0.95
0.54
3.16
0.78
0.57
0.54
0.97
0.63
—
0.74
Total Number
of Grains
Counted
1,374
2,671
2,955
3,617
2,894
1,428
7,974
4,815
3,110
3,447
2,652
2,321
2,291
2,651
3,392
Percent
Flyash
18,2
18.2
13.4
8.2
12.5
14.5
4.6
31.7
9.4
5.9
6.9
9.0
7.2
7.1
16.0
Diameter of
Largest
Flyash Grain
Micrometers
7
13
16
9
9
22
19
9
7
4
7
10
9
12
14
Columbia*
Flyash %
0
0
0
0
0
0
2
83
4
8
5
12
9
11
8
Differentiation criteria for Columbia flyash versus other flyash: Si > Al : Si »
Al; Ca > K : K > Ca; S not detected : S present; Na, Mg not detected: Na, Mg present.
FLYASH
In addition to sulfur dispersion, the other component of stack emissions that
has been monitored is the flyash, the very small-sized particles that escape the
electrostatic precipitator in this system. Initially, these precipitators were operating
at 98 percent efficiency, but the addition of sodium carbonate to the coal has
increased their efficiency to the required 99.5 percent. The data in table 5 are from
operation when it was about 98 percent efficient. Flyash was collected on the
ground in buckets at various distances from the power plant (3). In the first column
of table 5 is the total flux of flyash in milligrams per square meter per day reaching
the ground. By using an electron microscope, differences in shapes of the particulate
material can be determined. Dust, which is angular, can be removed as nonflyash
and constitutes a fairly substantial proportion. Flyash from other power plants or
other sources in the region is pitted from having traveled some distance, and flyash
from the local source has a smooth surface. Thus, from the number of grains
counted, it is possible to get an indication of the percentage of the total amount of
material that is local flyash. Figure 8A shows an example of the material collected
in a dust fallout bucket. Spherical grains are flyash and others are soil dust. It
appears that of the material coming down, approximately 20 percent is flyash, and
of that, 5 percent to 80 percent is of local origin.
132
-------
FIGURE 8—Scanning electron micrographs flyash particles in various environments. Bars
indicate scale in units of micrometers. A, an example of solid material collected in a dust
fallout bucket located in the vicinity of the Columbia Generating Station; B, a flyash
grain showing detailed surface deposits and morphology (32); C and D, hollow flyash
particles showing inner contents-the outer shell was penetrated using the electron beam
of the SEM (32); E, a large flyash particle on the surface of an oak leaf-the leaf surface
is pitted by the particle; F, small flyash grains and other dust shown on veins of an oak
leaf.
133
-------
DETAILED FLYASH STUDIES
Detailed studies of flyash particles indicate that their surfaces are highly
reactive after being formed during the combustion process and as they cool other
products of combustion in the gas phase condense, causing surface enrichment
(figure SB) (32). The surface enrichment of these particles cannot be measured by
analysis of a total sample (bulk analysis) and previous assessments of the possible
impacts have understated this potential by comparing the concentrations of
components with the earth's crustal abundance. This type of comparison
underestimates the availability of certain components which have been shown to be
readily extractable (32). A comparison of surface analysis to bulk analysis shows
concentrations (jU9/g) of lead 2,700:620; thallium 920:28; chromium 1,400:400; zinc
14,600:1,250; and arsenic 1,500:600. Disposal or use of flyash must be carefully
evaluated with these surface properties in mind.
Complex organic compounds such as polycyclic aromatic hydrocarbons that are
formed during the combustion of coal are also associated with the surface of flyash
particles. However, these compounds leave the stack as a vapor and condense on the
particles after the plume cools (32).
HOLLOW FLYASH
Some particles are hollow and contain additional smaller particles. These have,
in theory, the potential for timed release effects which may not be observable until
some future date. The electron micrographs shown in figures 8C and 8D show
examples of flyash particles of this type (32). The outer shells were penetrated using
the electron beam of the SEM revealing the inner contents.
MASS BALANCE APPROACH
Some evidence for highly reactive flyash particles is shown in figure 8E where
the surface of an oak leave is pitted and the leaf area around the particle shows
calcium enrichment attributable to the flyash particle (3). Figure 8F shows small
flyash grains and other dust or veins of an oak leaf.
During the period where the electrostatic precipitators were operating at 98
percent efficiency, about 1,051 pounds of flyash were being emitted per hour. This
mass is equivalent to about 1019 particles emitted per day (assuming one micron
diameter and a density of 1.65). Subsequent additions of sodium carbonate to the
coal have increased precipitator efficiency to 99.5 percent removal.
Using the sulfur and flyash emissions, it is possible to estimate the yearly
output and mass balance of materials from the stack (see table 3) which are arsenic
120 kg, cadmium over 90 kg, copper 2,000 kg, manganese over 10,000 kg, mercury
27 kg as a gas, and zinc over 2,000 kg. Based on these estimates, and through
further analysis, it is estimated that only between 5 and 6 percent of the emissions
from the stack come to the ground within 35 to 40 kilometers. Additional studies
are underway to determine the ultimate fate of the balance of these compounds
exported outside of the region currently under study.
A mass balance approach is in general a good technique to define areas where
additional information is required to determine missing components and the fate and
effects of emitted compounds.
In considering the effects of the gaseous emissions on vegetation, a wide range
of studies was possible because of the location of the plant in a highly productive
agricultural area (19). However, the studies are complicated because this area of
southern Wisconsin is where part of the St. Louis and Chicago plume contributes to
ozone levels in the summertime close to or above tolerance levels for some
vegetation. Mixtures of sulfur dioxide and ozone exist over the study areas and
detailed laboratory studies are being conducted to define the interactions. Figure 9
is based on experimental work in the laboratory, using controlled fumigations of
various pollutants. Ozone alone has an effect on peas (2-hour exposures) at a little
above 300 micrograms per cubic meter. However, in a mixture of ozone and sulfur
dioxide setting SO2 concentrations at over a thousand micrograms per cubic meter
(/Ltg/m3), damage occurs at lower ozone levels, down to about 75 (//g/m^) which
frequently occurs. Figure 10 shows the increase of effects of sulfur dioxide
concentrations on pea plant leaves with increasing ozone concentrations. Results of
this type may be used to revise and improve air quality criteria.
134
-------
100
V 90-
r 03 + SO2
(S02 at 1040
c
-------
LEAF INJURY
Normal sulfur levels in this system have never been very high. Before the
operation of the Columbia plant, a level of over 10 micrograms per cubic meter
dug/mS) was present 12 percent of the time (table 4). After the Columbia plant
went into operation, sulfur concentrations reached this level 17 percent of the time
and reached concentrations of 80 or 100 jUg/m3 a |jttle less than 1 percent of the
time. The ozone-sulfur interaction is shown in figure 10 from the other point of
view. Sulfur alone does not cause damage on this pea variety until it reaches a level
of over 2,000 |Ug/m3. But in combination with ozone at 340 jug/m3 a level reached
occasionally under current conditions, damage is seen ranging up to 100 percent at
levels where, without the ozone, damage would be less than 10 percent. Even at the
low sulfur levels common in the area, e.g., 80 to 100 ng/rr\3 the synergism with a
high ozone level could cause 10 percent damage on this particular variety of pea.
The likelihood of this combination occurring and generating noticeable effects in a
single year is minimal. However, species such as white pine and lichens could
accumulate significant effects from these low concentrations over several years of
exposure. Current plans call for monitoring these perennials for several years.
»
KEY:
- WHITE PINE SITES
COLUMBIA
GENERATING
PLANT"
FIGURE 11-Samp/ing sites for White Pine circling the Columbia Generating Station
SAMPLING SITES
Figure 11 shows the distribution of white pine sampling stations. At these
study plots, within about 15 kilometers from the power plant, white pine foliage
was examined for tip-burn symptoms during the growing season for 3 years prior to
the operation of the power plant and for 3 years since the operation of the plant.
The overall mean of the tip-burn observed during the growing season is highly
variable. However, studies of the sources of this variability are still underway. When
the damage levels at individual stations are combined for the before-plant and
after-plant operation, less variability results. Measurements have not yet been done
136
-------
of long-term (3-year) foliage loss from exposure at a chronic level because they
require observations of the pathology of the same needles each successive year. This
study requires that one look at foliage during the first year, and that continuous
measurements be made to determine what symptoms accumulate. The percentage of
the foliage lost by the third year is indicative of the pathology. The lichens in this
area show some increased plasmolysis but these observations have not yet been
studied in detail.
MEADOW
WET FOREST
FOREST
FIGURE 12-Outline of the Columbia Generating Station and the topography of the site
before construction
HYDROLOGIC SYSTEMS
AND COOLING LAKE
This study has examined impact on a coupled system, part of the generating
station that is governed by water flow through the area. Figure 12 shows the before
and after topography of the area (24). Before the construction of the system, the
upland sloped gradually to the flood plain sedge meadow and the river. A
groundwater flow from the adjacent uplands of about 1 cubic foot per second was
maintaining the water level in the sedge meadow. The flow is high in the spring
during snow melt, but flows would be much reduced during the summer. The 500
acre lake was constructed with a 9-foot hydrostatic head above levels in the adjacent
wetlands. Its construction has drastically altered the groundwater pattern. Figure 13
shows groundwater flows before and after construction of the cooling lake (22).
137
-------
CO
cc
<
>
_l
LLJ
230 -
220 -
210 -
200 -
190 -
BEFORE
RIVER
STUDY
SITE
COOLING LAKE ASH PIT DRAIN
AFTER
500
1500
2000
1000
METERS
FIGURE IS—Grotindwater flows before and after construction of the cooling lake. Arrows
represent integrated flows, 1 m^/min, normal to the east-west cross section along the
length of the cooling lake.
A MODELING APPROACH
There is now 4 cubic feet per second of seepage from the cooling lake, going out in
both directions, but mostly into the sedge meadow on the west. Thus, although the
lake has essentially cut off the groundwater flow from the adjacent upland, seepage
at this rate is keeping the sedge meadow in a flooded condition throughout the
year. Of ecological interest, not only are there now direct effects of the higher
water levels in the sedge meadow, but also that there is no longer any fluctuation in
water level during the growing season. Some of the species in this wetland are
dependent on the annual summer drying for certain stages of their life cycle. This
no longer occurs.
A modeling approach has been developed to aid in predicting the changes in
surface water levels in an impeded flow area, given a variety of changes in the
adjacent upland (22). This is a general case approach that applies whenever
construction is going to cause more runoff than occurred previously—such as along
highways where creation of an impervious surface increases the water flow to the
adjacent impeded flow areas. The models resulting from this approach will provide
useful aids in such situations and is a sample of the kind of information that can be
generated from a site specific study of this nature and generalized for many
applications.
138
-------
TABLE 6
Mass balance for the Columbia Generating Station lake
Input (kg/yr)
Element Dissolved Particulates
Total
Output (kg/yr)
Dissolved Particulates Total
Amount Remaining
in Cooling Pond
(kg/yr)
Particulate
Matter
Al
As
Ba
Ca
Co
Cu
Fe
K
Na
Sb
Si
Zn
S04
1,200
10
40
520,000
2
40*
6,000
40,000
200,000
40
42,000
100
260,000
18,600
6
197
6,200
3.4
5.3
13,570
3,325
1,170
0.8
87,930
112
114
266,450
19,800
16
237
526,000
0.4
45.3
19,570
43,325
201,170
41
130,000
212
260,114
80
2
8
124,000
0.4
40
401
7,620
40,000
8
2,400
20
52,963
1,900
0.9
28
850
0.3
0.5
1,010
385
892
0.2
16,300
25
16
49,400
1,980
2.9
36
124,850
0.7
#
1,411
8,005
40,992
8.2
18,700
45
52,979
217,050
17,820
13
201
401,350
4.7
#
18,160
35,320
160,178
33
111,300
167
207,135
A considerable amount of Cu is released to the cooling pond from the cooling system of the plant; precise
values not yet determined.
BIOLOGY OF COOLING LAKE
FISHERY
IN COOLING LAKE
The mass balance of materials in the cooling lake are shown in table 6
(1,3,14). Water is pumped in from the Wisconsin River with certain chemical
characteristics which vary from season to season. Water going through the plant
cooling condensers picks up waste heat, chlorine (defouling agent) and copper. Live
aquatic plants and animals in the system grow and are transformed into detritus.
Some of the water taken into the plant is used for flushing the ash to the ash
basin, although most is returned to the cooling lake. The remainder of the outflow
from the cooling lake occurs as seepage through the bottom of the cooling lake. A
comparison of the concentrations of chemicals and particulates in the input and
output water, (table 6) indicates that an accumulation is predicted in the cooling
pond: 217,000 kg of particulate matter, 17,000 kg of aluminum, 400,000 kg of
calcium, accumulating in the sediment at the bottom of the cooling lake as water
from the cooling lake evaporates and leaks out.
Because of the warm water and a long growing season, an interesting fishery is
thriving in the cooling lake. A macroinvertebrate species, a Hyalella sp., seems well
adapted to this cooling system in a particular temperature zone. In the summertime
it clusters near the plant intake. The small settling pond where the river water
enters the cooling lake may actually provide a refuge for some of the biota during
the few days of extreme temperatures during the hottest summer days. However, the
zooplankton population moves around the lake during cooler periods to wherever
the desired temperature is much closer to the warm water inflow during winter.
The fish feeding on this zooplankton are principally gizzard shad and black
crappie, both of them southern species that ordinarily grow in much warmer
temperatures than occur in Wisconsin. Two common Wisconsin species, bluegill
sunfish and largemouth bass, were stocked in the cooling pond. Both have grown
well, but the largemouth bass population is not reproducing; at the present time a
4-pound fish can be caught on the average with three casts. There has been strong
139
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public pressure to open the fishery, and for the first time it will be opened in
1978. Preliminary analyses of fish residues for metals or organic compounds show
low values. Of particular interest are mercury and chlorinated compounds.
Concentrations are elevated due to paper mill wastes in the Wisconsin River water
and additional chlorinated organic compounds are expected from the use of chlorine
in defouling the condenser tubes (34).
COOLING
LAKE
CROSS SECTION A
AUGUST 8, 1976
SEDGE MEADOW
10
30 m
COOLING
LAKE
5.5°C
CROSS SECTION B
DECEMBER 14, 1976
SEDGE MEADOW
10.60
10 -
30 m
FIGURE 14—Groundwater isotherms, °C, in vertical cross sections between the cooling
lake and the Wisconsin River
WASTE HEAT DAMAGE
One of the more interesting findings of this project concerns the conservative
nature of waste heat found in the groundwater due to the seepage from the cooling
lake. The movement of this waste heat into the groundwater has done the most
additional identifiable damage to the aquatic system observed since the construction
of the generating station (8). Figure 14, cross section A shows that in August, water
of 15 °C is rising from the sediment below the sedge meadow, whereas 25-degree
140
-------
CONSEQUENCES OF HEAT
RELEASE
water is measured under the dyke. In figure 14, cross section B shows that water at
20 C is rising in the sedge meadow but the water seeping in from the cooling lake
is at 5°C (22). In June, this cold water from the lake comes up at about 5 „
Although the 2° to 5° water in June doesn't bother the plants, the 20° water
around the root systems in the period from December to January causes serious
damage (13). The problem was unexpected since heat is not usually a considered
conservative component. As long as the deep below-ground deposits are at a low
enough temperature to take up some of the heat, this effect would not be
noticeable. However, 6 months of plant operations saturated the sediments to the
extent that any substantial body of additional heat could not be accommodated.
With both 527 MW units operating, it is predicted that little or no snow cover will
appear on the adjacent wetlands area after 1983 (22, 24) unless steps are taken to
eliminate the seepage from the cooling lake.
Ongoing studies in the sedge meadow revealed the biological consequences of
this heat release into the wetlands (15). Photographic studies of the sedge meadow
about 8 or 10 months after the initial operation of the power plant showed that in
November some photosynthesis was continuing late into the fall (17). This process
does not show up in other parts of the sedge meadow where there is similar plant
species composition. The result over a period of 2 years is extensive mortality and
decomposition and a comparatively open lake in the sedge meadow. Where there was
originally a dense mass of Carex lacustris, which is the ideal habitat for northern
pike spawning in the wetland, there is now very little cover during spring spawning
time. The cattails reproduce rapidly during the growing season and then are
decimated again during the following year. Thus, there is not only a loss of species,
but a change in the entire substrate, a reversion of the organic accumulation and an
initiation of the erosion process.
15
10
0 "-
15
10
U
AREA 01
f -•- v i —;
_l__l l_J . 3.5 ± 2.4cm
AREA 02
J 15
I
I- 10
O. '"
Ul
Q
DC 5
UJ
I-
2
10
5
o
LU
^m
EMPERATl
D CJ1
Z
10
5
n
-5
"
-
• •
, II
II 1
JAN FEE MAR APR
_____ — — — — — — — —98 + 32cm
il.ll
128 + 2 7 cm
i AREA 09
1 1
MAY JUN JUL AUG SEP OCT
FIGURE 15— Water depth and temperatures of impacted wetland areas. Bars represent
temperatures as degrees Celsius above or below temperatures relative to control sites.
TRANSITION IN WETLANDS
By late summer, however, annuals colonize these mudbeds and produce seed
which come up again the following year, with the net result of converting this area
from a perennial wetland community to a comparatively unstable wetland of
annuals. There is evidence of a transition going on in the wetland, probably brought
about by a combination of the changes in water level, flow rate, temperature, and
perhaps dissolved components. Specific results are shown in figure 15. In some areas
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CARBOHYDRATE LOSS
of the wetland there is an enhanced water level of 12 centimeters due to the
increased flow of the groundwater system. The bars show the departure from
temperature of control areas at that time. Areas farther from the cooling lake
receive the warm water at a later time. In area 9 there is an enhanced temperature
of 18 degrees during the winter, tailing off to a depression of 2 or 3 degrees in the
summertime and then back up. In this area, which is farther away, the minimum lag
for the warm water of the previous summer coming up in the wetlands seems to be
4 or 5 months. For much of the area the lag is 6 months. Some areas show a time
lag until May before the main temperature enhancement takes place, and then the
summer depression is not as severe. There are mixed areas with combinations of
magnitude of temperature enhancement and of the magnitude of delay. If the
temperature enhancement is fully 12 months delayed, it is probably not out of
phase with the life cycle of the plant and little damage may occur except for that
induced by water flow or depth effects.
A number of hypotheses exist to explain the pattern of plant responses in the
wetlands. The principal one concerns the probable decline in carbohydrate storage of
the plant in relation to the materials needed to grow the following spring, due to
elevated fall and winter temperatures. This has been shown to be the factor inducing
winter mortality of Typha latifolia (13).
CAREX LACUSTRIS
1.00
co .90
0 .80
O
I .70
CO
u. .60
O
tn .50
m .40
5
§ .30
^ .20
< .10
O
March, 1977
.
„
-
-
.
-
A
•1
• •• CONTROL
A ^ AREA 01
• im AREA 02
* i" AREA 09
1
i i i
April, 1977
.
.
.
•
.
•
A
. t ,1
>
1
1
1 I
h-
w .70
0 .60
O
I .50
co
0 .40
S .30
I .20
Q .10
September,1 977 ^
•
.
^ •
1
h 1
. |
i 2 i I
g
j
" October, 1977
-
_
A
• 1
II
• II
i p ''P
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i i i j
10 20 30 40 50
10 20 30 40 50 60
MEAN HEIGHT OF NEW SHOOTS (cm)
FIGURE 16—Monitoring data for Carex tacustris in the wetlands adjacent to the cooling
lake of the Columbia Generating Station
ADDITIONAL MONITORING
Carex lacustris on the other hand, does not show a loss of carbohydrate such
as in the Typha. The levels are reduced but the depression of carbohydrate can't be
regarded as the principal reason for the mortality of these species. The data in
figure 16 show that the emergence of Carex lacustris is adapted to the temperature
in its environment. In areas most affected by warm water, high levels of total
number of shoots present during March and April are seen, but in the control areas
they have not emerged. Thus, of the two sedge species that were seriously hurt in
this particular area, there appear to be two or more mechanisms involved in the
collapse of the communities. Additional monitoring of the reestablishment of other
species is needed to project whether a stable plant community can be supported.
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ADDITIONAL WORK
Additional work on the fishery of the wetland over a period of years will be
needed to determine whether a decline in northern pike and muskelunge
reproduction due to the decline of the quality of the sedge meadow as a
reproduction medium will be a major problem.
9-
10-
11-
12-
13-
MEAN FOR ALL 14.
SAMPLES
15-
16-
17-
18-
19-
20-
21
22 H
23
s
36'
37 J
•YELLOW WARBLER
•DRYOPTERIS THELYPTERIS
-CAREX STRICTA
-COMMON YELLOWTHROAT
-SWAMP SPARROW
. CALAMAGROSTIS CANADENSIS
RED-WINGED BLACKBIRD
LYSIMACHIA THYRSIFLORA
. CAREX LACUSTRIS
LONGBILLED MARSH WREN
SAGITTARIA LATIFOLIA
LEMNA MINOR
CAREX ROSTRATA
TYPHA LATIFOLIA
AVERAGE WATER
DEPTH (cm)
FIGURE "\7-Diagram showing correlation of bird communities with wetlands plant species
and water depth
BIRD AND PLANT
SPECIES CORRELATION
Other research has been directed toward the relationship of the bird
community in this system (15). This has been done principally by correlating bird
species with particular plant species (figure 17). Yellow warblers and yellow throat,
are associated with Carex stricta; in slightly deeper water the redwing blackbird and
Xhe marsh wren are usually associated with Carex lacustris. As the marsh is
undergoing change due to the combination of water and temperature treatment, the
other changes that follow must be monitored as they in turn will induce changes.
Figure 18 shows the complex interconnections between the power plant and the
bird communities. A gradual but small growth in waterfowl populations is occurring.
Ducks did not use the area at all previously, but they are now beginning to use the
emerging water patches. Some people have suggested that this should be regarded as
a resource enhancement, just as the cooling lake fishery would be thought of as a
resouce enhancement.
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AIR-BORNE
CHEMICALS
FIGURE 18—Schematics of interconnection pathways between the Columbia Generating
Station and bird communities
PUBLIC ECONOMY
AND FISCAL STATUS
SITE IMPACTS
Several subprojects deal with the response of adjacent human communities in
some depth, including visual impacts and citizen concern with electric generating
stations (20,29,31). One of the most dramatic impacts of the Columbia Generating
Station is shown in table 7 concerning the public economy and the fiscal status of
Pacific township where the station is located. The rapid growth in utility tax
revenues paid to Pacific, following the initiation of construction in 1971, are given.
Column 3 reflects the total tax levy imposed on the municipality by the state,
county, and appropriate school districts. Column 4 depicts the actual amount of tax
that was assessed and collected from local property owners. The final column
illustrates the rapid growth of town excess funds, which have been invested in
certified deposits earning between 51/2 percent and 6V? percent annual interest. All
data prior to 1975 were extracted from the Official Financial Reports of Pacific
Township, filed with the Wisconsin Department of Revenue.
The resultant land use pattern changes are shown in figure 19 in comparison
with a control township. The net result from Wisconsin tax laws show that an
agricultural area is being strongly driven toward residential land use. This type of
impact will depend on state law and vary greatly from state to state.
From the samples of research results given above, one can conclude that the
electric generating station and the impacted environment are not a closely coupled
system in the same sense that a watershed is a coupled system with known inputs
and transfers that are linked throughout. Portions of this system are directly
coupled; certainly the system from the leakage of the cooling lake, through the
wetland plants, to the birds supported by the wetland operates as a coupled system.
However, this is only one part of the system, and must be considered in evaluating
the total ecological impact of the generating facility itself.
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TABLE 7
Budget figures for pacific township
Year
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
Utility Tax
Revenues
(Including
Makeup)
$ 19,935
59,937
388,969
1,171,344
752,248
745,014
725,000*
700,000*
675,000*
650,000*
Total Tax Levy
(State, County,
School)
$ 176,176
184,903
201,046
201,735
213,000*
266,000*
239,000*
253,000*
268,000*
284,000*
Total Local
Tax Collection
$ 154,635
152,720
25,283
0
0*
0*
0*
0*
0*
0*
Total Town
Investment Fund
(Annual Interest
not Included)
$ 50,958
81,922
320,000
1,311,902
1,851,000*
2,470,000*
2,956,000*
3,403,000*
3,810,000*
4,176,000*
Estimated projections based on current data and trends.
RESIDENTIAL LAND USE 1962-1974
350 -
1962
1966
1970
1974
FIGURE '(S—Land use pattern changes as a result of the construction and operation of
the Columbia Generating Station in Pacific township compared to Fort Winnebago
township
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MASS BALANCE APPROACH
The mass balance approach can be recognized as an essential tool for summing
up and following the materials through a complex system and determining where
they go. It appears that the atmospheric transport mechanisms for the gases and fine
particulates are so efficient in leaving this site that one cannot define the magnitude
of the area in which the deposition and effects will eventually take place. These
effects are added increments to ecosystems already receiving pollutant loadings from
other sources. If the added materials are responsible for unacceptable environmental
degradation, then additional controls will have to be imposed to prevent their
release. Acid rain impacts are starting to appear as an important remote impact and
may be expected to spread and intensify as more coal is burned and sulfur and
nitrogen oxides increase the loading of already stressed ecosystems.
Beyond the issue of how best to study or assess the effects of a large
coal-fired generating station, there is also the larger question of how to make the
results of these studies known in siting future power plants. Obviously, assessment
of the trade-offs requiring the technological fixes to minimize the adverse ecological
impacts is a complex of comparative impacts. Perhaps more efficient flue gas
scrubbers should be employed rather than a tall stack for removing sulfur and
nitrogen oxides, gaseous metals (including mercury), halogens (fluorine, chlorine,
bromine, iodine compounds), and polycyclic aromatic carbon compounds. The nature
of the emitted flyash particles suggests that total paniculate removal rather than
99.5 percent may be justified in the future. Actual field evaluation of water quality
criteria may show that aquatic systems may be less sensitive to ash basin effluents
than laboratory derived criteria have predicted.
ACKNOWLEDGMENTS
These questions and many others will be answered if the resources needed to
complete the research program and generate the needed answers are forth-coming.
The information in this report is derived primarily from the research
conducted by the faculty and staff of the University of Wisconsin, Madison. Special
thanks are due to Professors Orie Loucks and Philip Helmke of the University of
Wisconsin, Madison who provided most of the material for this report. Many
additional important findings are contained in the reports listed in the bibliography
and are not summarized here only because of time and space constraints. Thanks are
also due to B. Halligan for drawing the figures and T. Highland for typing the
manuscript and D. Mount, K. Biesinger, L. Heinis and L. Anderson for reviewing it.
146
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References
Titles (some tentative) and authors of reports resulting from research at the
University of Wisconsin, Madison-Grant R803971 (numbers 1-31).
1. The Flow of Elements in an Aquatic System Surrounding a Coal-Fired Steam
Plant by Anders Andren, Marc Anderson, Nicholas Loux and Robert Talbot:
July 1978.
2. Distribution of Polycyclic Aromatic Hydrocarbons in Soils Surrounding a
Coal-Fired Power Plant by John Harkin and Barbara Kaehler: August 1978.
3. Impacts of Coal Combustion on Trace Elements in the Environment by Philip
Helmke, Wayne Robarge, Paula Burger, Myles Schoenfield, John Thresher,
Robert Koons, and Glenn Hanson: July 1978.
4. Uptake and Distribution of Xenobiotic Compounds in Fish by John Lech and
Mark Melancon: July 1978.
5. Air Pollution Dispersion and Deposition Study of Coal-Fired Generating
Stations by Kenneth Ragland, Bradley Goodell, Terry Coughlin and Emilia
Estrada: July 1978.
6. Meteorology Studies at the Columbia Generating Station by Charles Stearns
and Leonard Dzamba: September 1978.
7. Formation and Large-Scale Transport of High Ozone Levels in the Central and
Eastern United States: A case study by Brent Bowen and Charles Stearns:
June 1978.
8. The Impact of the Columbia Generating Station on the Local Groundwater
System by Mary Anderson and Charles Andrews: July 1978.
9. Water Constraints in Power Plant Siting and Operation by Erhard Joeres, Nate
Tetrick, and Nancy Cichowicz: July 1978.
10. Response of Aquatic Invertebrates to an Ashpit Effluent by John Magnuson,
Ann Forbes, Dorothy Harrell, and Judy Schwarzmeier: July 1978.
11. Responses of Fish Populations to Habitat Modifications Resulting from a
Coal-Fired Generating Station by John Magnuson, Michael Talbot, Frank Rahel,
Ann Forbes, and Patricia Medvick: July 1978.
12. The Cooling Lake Ecosystems: Circulation, Physical and Chemical Limnology,
Biology and Stability by James Kitchell, Steve Lozano, and Dennis Rondorf:
July 1978.
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13. Response of Wetland Plants to the Development of an Adjacent Cooling Lake
by Barbara Bedford, Orie Loucks, Daniel Willard, William Jones, and Jay
Benforado: July 1978.
14. Response of Wetland Animals to the Development of an Adjacent Cooling
Lake by Daniel Willard et al.: September 1978.
15. Predicting Impacts of an Electric Generating Station on Wetland Passerines by
Michael John Jaeger: July 1978.
16. The Use of Digital Film Analysis for Land Resources Inventory by Warren
Buchanan and Frank Scarpace: April 1978.
17. The Use of Air Photo Data in Conjunction With Ground Verification Data in
the Analysis of a Power Plant Site by Sarah Wynn and Ralph Kiefer:
September 1978.
18. Sampling of Alfalfa, White Pine, and Lichens for Air Pollution Damage Around
a Coal-Fired Generating Station by Theodore Tibbitts, Susan Will-Wolf, David
Olszyk, and David Karnowsky: July 1978.
19. Determining Herbaceous Vegetation Impacts from Coal-Fired Generating Station
Air Pollutants by Theodore Tibbitts and David Olszyk: September 1978.
20. Public Attitudes and the Visual Impact of Electric Generating Stations in Rural
Landscapes by Bruce Murray and Diane Burgess: July 1978.
21. Data Sets, Descriptions, and Evaluations from the Columbia Generating Station
Impact Study by Lawrence Fisher and Saya Sachem: October 1978.
22. Surface and Groundwater Response to a Floodplain Cooling Lake by Robert
Terrell, Charles Andrews, and Mary Anderson: May 1978.
23. Models for Forecasting Biological Responses of Sulfur Dioxide Plumes by Jerry
Shelton, Robert Terrell, and Orie Loucks: July 1978.
24. The Environmental Effects of the Columbia Generating Station 1975-1978:
An Overview Report by Orie Loucks, et al.: July 1978.
25. Environmental Impact Analysis of Transmission Systems by David Younkman
and Bruce Murray: July 1978.
26. Transmission Lines: Environmental and Public Policy Considerations: (An
Introduction and Annotated Bibliography) by Thomas Smith, John Jenkins,
John Steinhart, Kathleen Broidy, and David Schoengold: May 1978.
27. Wind and Solar Energy Alternatives by Carel DeWinkel and John Steinhart:
October 1978.
28. Transmission Lines: Technical Considerations by Farrokh Albuyeh and James
Skiles: November 1978.
29. Citizen Concern With Power Plant Siting by Elin Quigley, Jill Randall, Bruce
Murray, and Alice D'Allesio: July 1978.
30. Rationale for a Siting Protocol by John H. Williams and Bruce Murray: July
1978.
31. Impact of a Power Generating Station on Local Land-Use and Ownership
Patterns by Michael Patrick Shaver: July 1978.
32. Characterization of Trace Elements in Fly Ash by D. F. S. Natusch, C. F.
Bauer, H. Matusiewicz, C. A. Evans, J. Baker, A. Loh, and R. W. Linton, Intl.
148
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Conf. on Heavy Metals in the Environment, Toronto, Ontario, Canada. October
27-31, 1975 pp. 553-576; Science 191, 852-854 (1976).
33. Atmospheric Diffusion by F. Pasquill, Ellis Norwood, Ltd., Chichester,
England, 1974.
34. Chemical/Biological Implications of Using Chlorine and Ozone for Disinfection
by R. M. Carlson and R. Caple, EPA Ecological Research Series, EPA-600/
3-77-066, June 1977.
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ZZ7
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TRANSPORT PROCESSES AND ECOLOGICAL EFFECTS PANEL DISCUSSION
Allan Hirsch, Ph.D.
Fish and Wildlife Service
U.S. Department of Interior
John M. Neuhold, Ph.D.
Utah State Ecology Center
Utah State University
Stanley Auerbach, Ph.D.
Environmental Science Division
Oak Ridge National Laboratory
Herbert C. Jones, III, Ph.D.
Division of Environmental Planning
Tennessee Valley Authority
A. Paul Altshuller, Ph.D.
Environmental Science Research Laboratory
U.S. Environmental Protection Agency
(Additional comments by presentation speaker Dr. Pueschel)
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DR. HIRSCH: We have just heard four excellent papers describing research findings
related to transport process and ecological effects. Each of these four papers
contributes significant insights and findings. Yet, relating research findings to
regulatory controls is probably one of the most difficult aspects of environmental
management.
We have heard that over the long run many of these ecological impacts
resulting from long-range transport could be extremely significant. However,
predicting environmental transport, transformation, and ecological effects of
pollutants is extremely imprecise. It is often very difficult to predict the actual
ambient levels with any great degree of accuracy. It is even more difficult to assess
the ecological effects of those ambient levels, particularly effects of a subtle or a
long-term nature. With changing technologies and changing pollutants, precise
prediction certainly is not going to become any easier. Yet, in making regulatory or
control decisions, we have to be precise. We must quantify the emission standards or
the effluent limitations precisely in order to establish meaningful, realistic regulatory
programs. That is the dilemma. On the one hand, no matter how good the research,
we continue to have difficulty in predicting ambient levels with precision, and even
more difficulty in predicting impacts, particularly long-range or subacute, with
precision. On the other hand, we need to be very specific about regulatory
requirements when a plant is being sited and a standard is being set.
From a management standpoint this dilemma has already been reflected in
national pollution control policy. Perhaps the most clear-cut example of this is in
the 1972 water pollution legislation, which put heavy emphasis on effluent and
technology base controls, recognizing the difficulty of basing a regulatory program
on ambient conditions. Even there, however, if we look at the 1977 amendments,
we have achieved a basic level of effluent control and are now becoming concerned
about the residual ambient impacts.
It seems, therefore, that the basic issue before us today is what all this means
for the future of energy research. Do the data tell those concerned with the
planning or allocation of resources to energy research programs anything about the
direction and -emphasis of future research efforts? The issues are similar to those
posed by the health effects panel this morning. Should we continue trying to refine
our understanding of the effects of trace contaminants on aquatic ecosystems or of
sulfur oxide discharges on terrestrial systems and vegetation? Should we continue to
emphasize the development of better transport models? Or should we instead say
that we are only going to be able to marginally improve this predictive capability
with additional research and that we are not really able to apply very well what we
know now in the regulatory process? Should our research focus on developing
strategies for environmental management, adaptive systems of controls by which we
can rely more heavily on monitoring, feedback, and adjustments in control
mechanisms, with less dependence on up-front prediction of impacts as a basis for
specifying the control or management program? What mix of all these should we
have in our research programs?
DR. NEUHOLD: Two points made in the presentations are worthy of note. The
first involves the complexity of the transport phenomenon itself to the point of
impact on living organisms. The second is the importance of ecosystems in the
entire process, Heretofore, most of our effects work has concentrated on two areas:
human health effects and effects on individual organisms. Ecosystems, however, are
composed of populations of many diverse organisms, which perform various
functions. We depend upon our ecosystems for food, fiber, and many other vital
resources. The estimated 21/2 percent reduction in the production of Scandianavian
forests is appalling, yet we can look forward to similar reductions in this country.
Although our predictive ability is improving, it is by no means at a point yet
where we can be very specific about levels of toxicants in the atmosphere or in the
environment in general. Developing a strategy to handle toxic levels either at
emission or at ambient sites is extremely important. Concentration of emissions or
concentrations in the ambient environment are variable. In the mountainous areas of
the western United States, for example, because of the peculiar air shift patterns, it
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is not feasible to rely on simple emission standards. Even if the emission standards
are very low, we must be aware that at times of temperature inversions ambient
levels may be extremely high.
Our immediate need to utilize available sources of energy, such as coal, while
awaiting development of cleaner sources, forces us to have flexible policy relative to
both ambient and emission standards. What we now consider to be conservative
levels, in terms of human health or organismal effects, may prove to be too high to
avoid ecosystem consequences of a long-term nature.
DR. AUERBACH: Simply stated, on one side is the environmental scientist with a
lot of environmental information that he claims is bad. On the other side is the
technological scientist, who claims there is no demonstrated cause and effect at all.
In the middle is the regulator, asking what he should do. In many ways the
problem is analogous to the human health problem, in that we are dealing with
morbidity rather than mortality in the ecological context. We are trying to perceive
and measure effects which can be considered only at the morbidity level in our
various ecosystems.
It is obvious that we are dealing here in an area of ill-defined risk. We must
look at the potential costs if we do nothing about this risk. In terms of damage to
our renewable resource, food, and fiber structure, the potential cost is very great.
This is a transcontinental problem covering an increasingly larger area. We don't
want to lose ground while we are upgrading the measurement system to report to
the regulators the consequences of the impacts of pollutants.
Ecosystem degradation is a difficult concept, because the landscape is
composed of multiple species. In the time span of observation that most of us are
used to, we don't see the subtle changes, the shifts in species, which over a longer
term may result in the landscape's performing less well. This presents a challenge.
From the regulatory point of view, the emphasis is on a flexible system by
which, as the information develops, new modes of regulation may be instituted. For
example, the 1977 Air Amendements approved the new concept of offset
mechanisms, acknowledging that regions have a limited capacity to receive pollutants,
and new polluting agents must be treated in a manner which in some way offsets
the old polluters. This concept may not yet apply to transcontinental problems such
as acid rain, but it is a step in the right direction.
Similarly, with regard to emission standards we are waiting to see how well
the best applicable control technology (BACT), mandated to go in over the next 10
years, will work in ameliorating the impacts of gaseous air pollutants, Because of the
constantly changing nature of the air mass, measures such as emission budgets or
emission fees are not appropriate. Offset mechanisms may be the solution.
Potentially, NEPA could be applied to siting processes and combined with the
regulatory system to avoid detrimental effects on a continuing basis.
In long range terms, we need to explore methods other than straight
combustion of coal to produce the energy we need. We need to explore methods
which produce fewer direct gaseous effluents, and we need to couple this with
better degrees of control.
DR. JONES: If, in balancing the need for regulatory certainty with the inherent
uncertainties of environmental science, we neglect the environmental impacts,
particularly as they apply to health and welfare, then we are neglecting the basis for
the Clean Air Act and other regulations. The problem with many of our regulations
is that they do not have a good scientific basis to begin with, and that is, at least
in part, a monetary consideration. We are currently spending perhaps $25 million or
$30 million a year on environmental effects projects. At the same time, regulatory
decisions are having to be made which may cost a single agency or power producer
$500 million a year. Our regulations have far outstripped our predictive capabilities
as far as transport, transformation, dispersion, and impacts are concerned. The Clean
155
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Air Act Amendments mandate prevention of significant deterioration, and non-
attainment will require the use of models to predict very small increments of air
quality. If we are unable to accurately predict these increments of air quality,
growth and energy production could be significantly reduced. We need, therefore, to
pay considerable attention to obtaining the data and information with which to
validate and refine models.
A second consideration is to put more effort at this time into doing a
thorough evaluation of new environmental control or production technologies so that
we understand the associated problems before we commit ourselves. We know we
have effective and workable environmental controls. Applying some of our past
experiences could prevent us from getting into the sorts of difficulties we had, for
example, concerning hydrocarbon regulations for automobiles. Another example may
be the problem of sulfate reduction through SC>2 control at energy sources and
power plants. It is possible that scrubbers, particularly wet scrubbers, may actually
intensify the sulfate problem. Some attention is now being paid to that particular
problem, but a further problem may exist in that the reduction in sulfate levels may
not be proportional to the reduction in sulfur dioxide levels. We may expend
tremendous amounts of money in trying to achieve 90 percent control and still not
reduce sulfates to desirable levels. One of our current problems lies in developing a
thorough understanding of the kinetics of the reactions that lead to sulfate
production. The rate-limiting steps may be based on urban pollutants, and scrubbers
may not be an effective solution.
We need to spend more time looking at new pollutants, nitrates in particular.
It now appears that nitrates contribute significantly to the acidity of rainfall, yet in
1974 the problem was attributed to sulfur dioxide emissions from power plants.
Controlling oxides of nitrogen is going to be a much bigger problem. It may mean
more stringent controls on automobile emissions and more extensive controls on
power plant emissions. If we don't consider these things now, we may end up with
our power plants producing electricity just to run control equipment.
DR. ALTSHULLER: I would like to discuss briefly how research and development
may lead rather than lag regulatory decisions. An example of the impact of research
in this respect shows up in the 1977 Clean Air Act Amendments. We see there, for
the first time, the recognition by Congress that in the case of ozone one must
consider the problem on a regional rather than an urban or local basis, and a call
for developing guidelines for regional ozone models. This may be just the tip of the
iceberg. If we consider sulfates, nitrates, and perhaps organic aerosols, with respect
to acid precipitation, we see that, although there may be a thin basis of research, all
of these may involve long-range transport and regional-scale problems. In contrast,
therefore, to what could be called the classical air pollution situation, in which
concern is with local effects and local impacts of such things as carbon monoxide or
S02, our concern will increasingly be on a more regional basis.
To individual communities this presents the problem of ascertaining where
pollution comes from and in what proportions. Stated very simplistically, the
methods for obtaining this information, are monitoring and modeling. On a regional
basis, monitoring becomes increasingly difficult because at best one has at rather
high cost a thin service network which does not answer the critical question of what
is being transported aloft from elsewhere into the area. There is, therefore, increased
need for the development of reasonable models, and an understanding of transport
transformation rates and deposition is essential to this development. Fortunately, we
do not have to understand each individual species, as a lot of meteorology has a
common effect on all the species.
In terms of chemistry, the problem becomes more complex. It is interesting to
correlate the summertime sulfate peaks, in both air quality and acid precipitation;
the summertime ozone peaks; and the summertime peaks of nitrites—organic nitrate
and nitric acid-which are indicated by data, albeit sparse, from both the United
States and Japan. We heard earlier about the biological interactions of sulfate and
ozone on animals and of S02 and ozone on plants. There are interactive patterns,
and they seem to be more abundant during the summer months. The reasons for
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this are extremely complex, but they are inevitably photochemical reactions: the
radical species which convert S02 to sulfate also convert nitrogen oxides to nitrate
convert and form the ozone and the organic aerosols. The effects of these various
pollutant combinations suggest that, since we cannot focus our attention everywhere,
we should direct our research toward the summer rather than the winter
phenomena.
Finally, we must also remind ourselves that new energy sources interact with
urban sources, particularly in terms of health effects. We need to really understand
the interactions between surface and near-surface urban sources and elevated sources
as they affect air quality. This further complicates the problems in monitoring and
modeling because again there is the problem of separating the local urban
contribution from that which is imported.
DR. PUESCHEL: One of the severe handicaps in predicting the effects of pollutants,
specifically pollutants from coal combustion to produce energy, is our failure to
identify properties of certain pollutants which relate uniquely to their origin as well
as to their effects. A case in point is visibility, which by act of Congress is an air
quality standard in the western United States and which EPA has responsibility for
regulating. Professor Wilson finds a strong correlation between visibility in the
eastern United States and the sulfate concentration. This could be the case, but Dr.
McNelis has also pointed out that in the western United States, specifically in Utah,
a reduction of visibility by a factor of three is not related to an increase in sulfates.
The particles change. These, by virtue of their shape and elemental composition
are either nitrates—and in addition to the acid rain problem, there is a correlation
indeed between nitrates and visibility—or polymerized hydrocarbons from perhaps
two sources. These sources are the combustion of gasoline in automobiles, known as
smog, and the vegetation. The hypothesis for particle formation by hydrocarbons
from trees was postulated as early as 15 years ago. This is an example of a cause
and effect relationship which must be understood before considering any regulatory
measures for power plants which operate in the vicinity. Research is needed to
increase our capability of detecting specific properties to establish this cause and
effect relationship.
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questions
« answers
Dr. Edward S. Rubin
Carnegie-Mellon University
QUESTION
The panelists' discussions this afternoon have been
exclusively about power plant pollutants, particularly
SO2 and SO4. Could the panel discuss the contribution,
particularly in the eastern United States, of the other
types of urban area pollutants that Dr. Altshuller
referred to? For example, for residential, commercial,
and industrial activity a lot of oil is used, that also
releases SO2 at lower elevations. Obviously that has
significant regulatory overtones.
RESPONSE: Dr. Stanley Auerbach (Oak Ridge National
Laboratory)
In general, the EPA and other agencies have done
analyses based on ambient S02 standards. Their projec-
tions show foci of S02 around certain urban areas in
the eastern United States. They are very clear. The
decided peaks in ambient S02 are of particular interest
to the human health people. What we don't know is
how these urban areas contribute to transcontinental
and regional areas. On an ambient basis they are very,
very pronounced.
159
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mining methods
^•^^
• • B
and reclamation
chapter 4
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CHAPTER CONTENTS
mining methods and reclamation
METHODS FOR THE CONTROL OF ENVIRONMENTAL DAMAGE
CAUSED BY MINING ENERGY PRODUCING MATERIALS
Ronald D. Hill, US EPA
Eugene F. Harris, US EPA rngfc
S. Jackson Hubbard, US EPA 165
MINED LAND RECLAMATION
Willie R. Curtis, U.S. Department of Agriculture 18T
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MINING METHODS
AND RECLAMATION
A DESTRUCTIVE PROCESS
METHODS FOR THE CONTROL OF ENVIRONMENTAL DAMAGE
CAUSED BY MINING ENERGY PRODUCING MATERIALS
Ronald D. Hill
Eugene F. Harris
S. Jackson Hubbard
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
By its very nature the extraction of fuel is a destructive process.
Environmental degradation is bound to occur. In figure 1, the numerous emissions
produced by the extraction process are illustrated. These environmental insults can
be divided into several major categories: solid waste handling and disposal, water
discharges, air discharges, noise, and aesthetics.
Mining is the largest producer of solid waste in the United States. Not only
must large volumes of rock and soil be removed to extract a fuel, but additional
large volumes are produced when the material is processed. The handling and
disposal of this solid waste is the major cause of drastically disturbed lands. When
improperly disposed, ground and surface water pollution, fugutive dust, landslides,
and aesthetic problems result.
ROCK WASTE
(LOW GRADE
ORE)
(GOB)
(ROCK)
r\i i
SEDIMENT
DUST VENTILATION
LEACHATE (UNDERGROUND
ACID ONLY),
HEAVY P ARTICULATES
METALS METHANE
SOLVENTS DOMESTIC
\ t
SPOIL
SEDIMENT
DUST
BURNING
ACID
SLIDES
HEAVY METAL
TOTAL DISSOLVED SOLIDS
t
SUPPORT
FACILITIES
\
DUST
RUNOFF
SEDIMENT
HEAVY >
METAL
ACID
S/
s^
TOTAL
DISSOLVED
SOLIDS
FLOODING
f
NOISE/
AIR NOISE
R/HMF
IVlilVC
A CCT^U CTT*t ^O
AESTHETICS
m ICT
UUo 1
s'
\ &
DUST NOISE
t t
LOADING
FACILITIES
ORE OR T
1INERAL Rur
.TO
BENEFICATION
OR SALEABLE
PRODUCT
MOFF
\TRANSPORTATION
\ DUST SEDIMENT NOISE
GROUNDWATER
TOTAL DISSOLVED
SOLIDS
DRY UP
A^l r\
\
\
LAND MOVEMENT
SUBSIDENCE
LAND SLIDES
HEAVY METALS
SALINE SEEPS
FIGURE 1-Emissions from extraction process
165
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ABANDONED INACTIVE
MINES
ENVIRONMENTAL PROBLEMS
During mining and beneficiation, environmental problems occur from the
runoff from the disturbed area, water in the pit area, dust and noise from blasting,
extraction, haulage, storage, and grinding; and oil, solvents, domestic and other waste
from the support facilities.
In addition to current mining operations, there exists a legacy of abandoned/
inactive mines. A 1969 Congressional study reported that inactive coal mines were
the source of 78 percent of acid mine drainage.
Pollution control from mining is strongly related to whether the mine is active
or inactive. Active mining operations are under the regulation of some state and/or
federal agencies and a responsible party; i.e., the mine owner is available. In the case
of the inactive mine, responsibility and ownership are often unclear, regulations and
laws are not available, and funds for pollution control are unavailable or must come
from the public sector.
The principle environmental problems associated with the mining of coal are
sediment, mine drainage, subsidence, and fugitive dust. For the purposes of this
discussion, these terms are defined as follows:
• Sediment means the undissolved organic and inorganic material transported
or deposited by water.
• Mine drainage is water discharged from the mine site. Acid drainage is water
with a pH of less than 6.0 discharged from an active or abandoned mine
and from areas affected by coal mining operations.
• Subsidence means the settling or sinking of the land surface due to drainage
or underground mine roof falls.
• Fugitive dust means those airborne particulate emissions that are generated
at ground level as a result of equipment activity or material transfer.
SEDIMENT
Sediment in water reduces light penetration and alters the temperature which
directly affects aquatic flora and fauna. Fish production is hindered because food
organisms are smothered, spawning grounds destroyed, and pools filled. Sediment
places an additional burden on treatment plants and increases cost as well as
lowering aesthetic and economic values. Sediment deposit in navigable streams must
be removed at a high cost. Streams filled with sediment have reduced carrying
capacity and are subject to flooding.
The mechanisms of soil erosion by water consist of soil detachment by
raindrop impact and water scoring and transportion by surface flow. Sediment yield
can best be described by the Universal Soil Loss Equation (USLE) which combines
the principal factors that influence surface soil erosion by water. These factors are
precipitation pattern and intensity; soil erodibility based upon the soil characteristics
such as Texture, organic matter, clay content, and chemical properties; length of
slope; steepness of slope; cropping and management which takes into account the
vegetative cover, seeding method, and soil tillage; and erosion control practice such
as terraces and diversions.
MINING METHODS
CONTROL SEDIMENT
A study by Collier and others showed the average annual sediment production
from a surface-mined watershed was 42 tons/acre, more than 1,000 times higher
than an unmined watershed. Curtis studied three watersheds in Kentucky and found
the sediment yield to range between 0.84 and 1.27 area-inches per area disturbed.
He found little correlation between sediment yield and the amount of land disturbed
and concluded that methods of mining and handling the overburden are major
factors controlling sediment yield. He also noted that the highest sediment yields
were measured during the first 6 month period after mining. This indicates the need
for more attention to activities during and immediately following mining and the
importance of an adequate cover of vegetation and of establishing control structures
as quickly as possible after mining ceases.
166
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POTENTIAL EROSION
ACID MINE DRAINAGE
The current state-of-the-art provides methods that can minimize the effects of
erosion. Mining methods such as haul-back, and mountaintop removal/valley fill,
when properly executed, can significantly control potential erosion. Engineering
formulas are available for the design of sedimentation ponds to catch sediment
before leaving the mine site. Areas that have been mined should be reclaimed as
soon as feasible in order to hold the soil in place and provide a good plant media.
Revegetation techniques are either available or are being developed to reclaim mined
areas in all areas of the country. In all cases, a soil technician or agronomist should
determine the proper species to be planted, the fertilizer and soil admendment
requirements, the necessary mulch, and where possible topsoil should be applied.
Prime concern in the selection of the cover crop is that of immediate cover
followed by a native species that will perpetuate natural cover.
There are still some problems that exist with the ultimate design of sediment
ponds. These include the application of erosion practices to mining situations and
the final development of sediment pond technology.
One of the most damaging waterborne contaminants from coal mining
operations is the acid generated from the exposure of iron sulfide minerals found in
the coal and overburden. Not only does the acid directly impact stream biota, eat
away metal structures and destroy concrete, but as a result of the low pH, other
ions such as heavy metals, become solubilized and are carried into water courses.
These ions are often toxic to aquatic life and render the water unusable for
domestic, municipal, and industrial use. In 1969 it was estimated that in excess of
10,000 miles of streams have been degraded by acid mine drainage from active
mines by industry and improved surface mining techniques. The quantification of
the impact of acid mine drainage in terms of dollars loss has never satisfactorily
been accomplished.
EXPOSED PYRITE ROCK
The removal of overburden often exposes rock materials containing pyrite (iron
disulfide, FeS2>. ~*"he oxidation of pyrite results in the production of ferrous iron
and sulfuric acid. A further reaction then proceeds to form ferric hydroxide and
more acid. As noted in table 1, the products of these various reactions are iron,
sulfate, acid, and the various heavy metals that may be associated with the host
pyrite such as Cu, Zn, Al, and Mn. Organics have also been found in mine drainage.
These are shown in table 2.
TABLE 1
Typical acid mine drainage
Parameter*
Mine# 2
Parameter*
pH
Acidity, CaCOs
Alkalinity, CaCOs
Ca, CaCOs
Mg, CaCOs
Fe, Total
Fe, Ferrous
Na
Al
Mn
S04
T.D.S
Conductivity
5.0
640
17
370
110
300
270
480
15
6
3040
4320
3760
2.8
470
0
210
93
93
0
2
31
4
610
1050
1190
As
B
Cd
Cr
Hg
Cu
Ni
Se
Zn
P04
0.01
0.5
0.001
0.05
0.0003
0.01
0.20
0.001
0.25
8.6
All units mg/l (liter) except pH and conductivity (micromhos/cm).
NOTE: In-house EPA data.
167
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TABLE 2
Organic priority pollutants found in coal drainage
methylene chloride
chloroform (trichloroethane)
bis (2-ethylhexyl) phthalate
benzen
toluene
1,1,2,2-tetrach loroethene
1,2—trans—dichloroethylene
di—n—butyl phthalate
1,1,1 —trichloroethane
trichlorofluoromethane
TABLE 3
Acidity figures for Appalachian area coal mines-1969
Source
Underground, Active
Underground, Inactive
Surface, Active
Surface, Inactive
Combined, Active*
Combined, Inactive*
Other
Acidity
1,000 Ib/day
614
1,712
28
361
60
238
245
3,258
Percent
19
53
01
11
02
07
07
100
*lncludes sources where underground could not be separated
from surface.
A UNIQUE POLLUTANT
Acid mine drainage (AMD) is a unique pollutant because acid generation and
discharges continue to occur after mining has ceased. The most comprehensive
survey of the magnitude of acid mine drainage discharges was reported in 1969. The
results of this survey are shown in table 3. Underground mines contribute over 70
percent of the acid mine drainage. Inactive mines are also a major contributor.
The acid mine drainage problem is essentially a regional one. Most of the
problem lies in the Appalachian Region. Acid discharges are also found in the
Interior Region such as in the states of Indiana, Illinois, and western Kentucky.
Except for some isolated situations, acid mine drainage is not a problem in the
western states because the coal and overburden are low in pyrite and have a high
alkaline content.
Control technology for the elimination of acid mine drainage can take one of
two forms. Steps can be followed during the mining operation to prevent the acid
from being formed. If this is not possible, numerous techniques are available to treat
acid that is being produced from a mine.
OXYGEN CONTROL
All techniques for preventing acid formation are based on the control of
oxygen. There are two mechanisms by which oxygen can be transported to
pyrite-conductive transport and molecular diffusion.
168
The major convection transport source is wind currents that can easily supply
the oxygen requirement for pyrite oxidation. Wind currents against a steep slope
provide sufficient pressure to drive oxygen deeper into the spoil mass. Therefore, a
factor to consider is the degree of slope after regrading. This is especially important
on slopes subject to prevailing winds, since the wind pressure on the spoil surface
increases as the slope increases.
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OXYGEN BARRIERS
Molecular diffusion occurs whenever there is an oxygen concentration gradient
between two points, e.g., the spoil surface and some point within the spoil. Oxygen
will move from the air near the surface of the spoil, where the concentration is
higher, to the gas or liquid-filled pores within the spoil, where it is lower. The rate
of oxygen transfer is strongly dependent on the fluid phases and is generally much
higher in gases than in liquids. For example, the diffusion of oxygen through air is
approximately 10,000 times greater than through water. Therefore, even a thin layer
of water (several millimeters) serves as a good oxygen barrier.
The most positive method of preventing acid generation is the installation of
an oxygen barrier. Artificial barriers such as plastic films, bituminous, and concrete
can be effective, but they have high original and maintenance costs and are used
only in special situations. Surface sealants such as lime, gypsum, sodium silicate, and
latex have been tried, but they too are high in cost, require repeated application,
and have only marginal effectiveness.
The two most effective barrier materials are soil, including nonacid spoil, and
water. The minimum thickness of soil or nonacid spoil needed is a function of the
soil's physical characteristics, soil compaction, moisture content, and vegetative cover.
WATER BARRIER
Vegetation not only serves to control erosion, but after it dies, it becomes an
oxygen user through the decomposing process. This further aids the effectiveness of
the barrier. The organic matter that is formed also aids in holding moisture in the
soil.
Water is an extremely effective barrier when the pyritic material is
permanently covered. Allowing the pyrite to pass through cycles where it is exposed
to oxidation and then covered will worsen the AMD problem. Water barriers should
be designed to account for water losses such as evaporation and should include at
least 30 centimeters (1 foot) of additional depth as a safety factor.
Additional measures to control AMD are water control and inplace
neutralization. Water serves not only as the transport media that carries the acid
pollutants from the pyrite reaction sites, but it erodes soil and nonacid spoils to
expose pyrite to oxidation. Facilities such as diversion ditches that prevent water
from entering the mining area and/or carry the water quickly through the area can
significantly reduce the amount of water available to transport the acid products.
Sediment and erosion control are needed both during and following mining.
Terraces, mulches, and vegetation, used to reduce the erosive forces of water are
effective measures to prevent further pyrite exposure. These measures usually are
performed during reclamation.
Alkaline overburden material and agricultural limestone can be blended with
hot acidic material to cause inplace neutralization of the acid and assist in
establishing vegetation. In some cases, grading directs acid seeps to drain through
alkaline overburden. These techniques are more applicable to abandoned surface
mines than to current mining, where proper overburden handling should prevent acid
formation. The major exception may be those situations where an underground mine
was breached and an acid discharge formed.
TREATMENT PROCESS
Certain discharges from extraction process cannot be controlled at the source
and, therefore, must pass through some type of treatment process. This is usually
the case at an active mine because specific discharge criteria imposed by the state
and federal government must be met. Inactive/abandoned mines present another
situation, because, although treatment may be the only acceptable method to
prevent environmentally damaging emissions, no party or funds are available to take
over the long term commitment of treatment.
EPA has developed effluent guidelines for most of the mining industry. These
guidelines, in general, recommend limits on the concentration of acidity and heavy
metals that can be discharged. Typical values are presented in table 4.
169
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INPLACE NEUTRALIZATION
SHORTCOMINGS
SUBSIDENCE
Neutralization is almost the exclusive treatment process used by industry
today. The neutralization process provides the following benefits:
• Removes the acidity and adds alkalinity.
• Increases pH.
• Removes heavy metals. The solubility of heavy metals is dependent on pH;
that is, up to a point, the higher the pH, the lower the solubility.
• Ferrous iron, which is often associated with acid mine drainage, oxidizes at
a faster rate to ferric iron at higher pH's. Iron is usually removed in the
ferric form.
• Sulfate can be removed if sufficient calcium ion is added to exceed the
solubility of calcium sulfate; however, only in highly acidic acid mine
drainage does this occur.
Some shortcomings of the neutralization process are:
• Hardness is not reduced and may be increased.
• Sulfate is not reduced to a low level and usually exceeds 2,000 mg/1.
• The iron concentration usually is not reduced to less than 3-7 mg/1.
• A waste sludge is produced that must be disposed.
Although several alkaline agents have been demonstrated to be successful in
treating acid mine drainage, lime has been almost universally accepted by the
industry.
Other treatment methods have been developed that produce a very high
quality of water. The two methods that have proven most successful are reverse
osmosis and ion exchange. The major drawback of these methods are their high cost
and problems associated with disposal of the waste products.
The mining of a substantial quantity of underground material such as coal
creates a void which in turn often produces a condition of instability within the
rock leading to the collapse of the overlying rock into the void often creating
surface subsidence. Subsidence begins as soon as the supports or pillars left in the
TABLE 4
Typical effluent guidelines for the mining industry
Maximum for
Any 1 Day
Average of Daily Values for 30
Consecutive Days Shall Not Exceed
pH
Fe
Cu
Zn
Pb
Total Suspended Solids
Hg
Cd
Cn
Al
As
Mn
6-9
1-7 mg/l
0.1 mg/l
0.4-1.0 mg/l
0.4 mg/l
30-70 mg/l
0.002 mg/l
0.10 mg/l
0.02 mg/l
1.2 mg/l
1.0 mg/l
4.0 mg/l
0.5-3.5 mg/l
0.05 mg/l
0.1 - 0.5 mg/l
0.2 mg/l
20-35 mg/l
0.001 mg/l
0.05 mg/l
0.01 mg/l
0.6 mg/l
0.5 mg/l
2.0 mg/l
170
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EFFECTS OF SUBSIDENCE
mine are no longer able to support the overburden weight. This condition may
occur during the mining operation or may not occur until many years after mining
has been completed and the pillars slowly decay to the critical failure point. Once
the overlying material falls into the mine void, then cracking and caving proceed
upward over a finite period of time often reaching the surface and causing
considerable damage.
Earth movements at the surface may result in many varied types of damage.
Buildings are more severely affected by the compressive and extensive strains
associated with subsidence than they are by the actual settlement. Highways, bridges,
water and gas lines may be sheared, twisted, or broken by strains and slope changes
produced by subsidence. Sewage lines are especially susceptible to changes of slope
that can locally reverse their direction of flow. Effects upon the natural environment
can also be quite dramatic. Natural drainage patterns can be changed resulting in
formation or occasional destruction of swamps. Surface streams often are intercepted
by subsided areas or induced rock fractures resulting in flow into deep mines and
loss of surface waters. In severe cases, groundwater supplies may be intercepted and
drained into underlying deep mines.
MAGNITUDE OF PROBLEM
WESTERN STRIPPABLE
RESERVES
No definitive national analysis of the amount of land affected by past mine
subsidence or of the annual or total property damage has been made. However, an
appreciation of the magnitude of the problem can be gained from the experience of
the Coal and Clay Mine Insurance Fund of the Commonwealth of Pennsylvania.
Although only a small portion of undermined and developed land in Pennsylvania is
insured (about 7,500 policies in effect), nearly $1 million is paid out annually in
damage claims. Approximately 2,800 separate subsidence incidents involving damage
have been reported for the anthracite fields of Pennsylvania alone. The U.S. Bureau
of Mines has estimated subsidence costs, both surface damage and control costs, for
a 12-county area in Western Pennsylvania for the year 1968 at $295,000 with an
additional $4.3 million of coal left in place to minimize potential surface damage.
These figures would be much higher under current economic conditions.
Each instance of subsidence is unique. Although the surface appearance of
subsidence features can vary greatly, occurrences can generally be classified as
pothole, linear, or regional.
The President's 1973 energy message encouraged the use of domestic coal to
meet the needs for energy. Since low sulfur coal lying in close proximity to the
ground surface is economically attractive to energy producers, much of the
near-surface coal resources in the West are important. The emphasis on use of
western coals has been reiterated by private and federal sectors with increasing
frequency.
According to U.S. Bureau of Mines estimates, the western coal fields contain
more than 60 percent of the strippable coal reserves in America. It has been
estimated by the federal government that, in 1985, 1.09 billion metric tons of coal
must be mined to meet the demand in the industrial, power generation, synthetic
gas, and export sectors of the market. This amount will double the coal production
of 544 million metric tons for last year. To achieve a total production of 1.1 billion
metric tons, nearly 300 million metric tons will have to come from western coal
fields to supplement the estimated 850 million metric tons derived from the
traditional coal-producing regions of the East and Midwest. Comparing that figure
with last year's production from western states of approximately 54 million metric
tons, one begins to grasp the scope of potential coal development in this area of the
nation. Although characterized by low Btu and high ash content, western coal
contains very little sulfur, and the large size of the coal fields makes them attractive
to the huge industrial plans that could result from future growth i.e., gasification
and liquefaction processes.
While the adverse impacts of coal mining in the eastern United States have
been well documented and intensively researched, relatively little is known
concerning the potential degradation that may result from large scale mining in the
arid West.
171
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SALINE WATERS
OCCUPATIONAL INTERESTS
OIL SHALE
Suspected water pollution problems are salinity, sediment, and groundwater
disturbance. To date saline waters have not been critical; however, preliminary
results indicate that saline discharges as high as 23 kg/meter of spoil can be
produced. The treatment of saline waters, beside holding and evaporation, requires
advanced methods such as reverse osmosis, ion exchange, or distillation that are
costly and at this time are not economically justified.
Some coal seams are aquifers and are a principle source of freshwater. Mining
may result in alteration of groundwater distribution by aquifer disruption. Presently
the magnitude of the aquifer disruption problem has been limited and methods to
mitigate the problem are just now under study. In addition, if solid wastes from
power plants and gasification plants are to be returned to surface mines where
aquifers were present, additional groundwater pollution problems may be created.
Western overburden material is of young geologic age and subject to excessive
erosion. Stabilization of the spoil, as quickly as possible after grading, is required to
minimize sediment discharges. Flash flooding and wind erosion constitute major
hazards in damaging soil loss. Possible air pollution problems involve fugitive dust
from extraction, loading, hauling, and support facilities. In addition, emissions from
spontaneous combustion of coal seams and waste materials could cause considerable
air quality degradation.
One of the major drawbacks to western reclamation is revegetation. Climatic
conditions are extreme. Seventy-five percent of the western coal fields receive less
than 50 cm. of annual precipitation. In addition to limited precipitation, seasonal
temperatures can vary from -51° to 49° C, only short frost-free periods are
available, wide variations are present in overburden material, and adequate topsoil is
lacking.
Water is the key to any successful reclamation program in the West. Ample
moisture at planting and during establishment is critical. Techniques for acquiring
additional moisture are being developed. These include studies on surface
manipulation, irrigation, and mulching and the impact of these practices on surface
and groundwater quantity and quality.
The people of the West generally express concern over expanded extraction in
terms of their own occupational interests. Not everyone is fearful about the effects
of developing the coal. There are people who view the development as something
good. They see increasing coal development in terms of an expanding economic
base, new jobs, better services, and a chance to broaden cultural horizons. Many
ranchers and farmers are worried about competition for land and water and about
the conversion of present and potential agricultural water supplies to industrial
usage. Some believe that mined land cannot be reclaimed nor shallow aquifers
rebuilt. A general concern shared by most people is the impact of air pollution on
range vegetation, crops, and abundant wildlife resources. The several Indian tribes in
the region are concerned over the impact of coal development on or near their
reservations in terms of water rights, resources, and cultural values.
Offsetting this rather gloomy picture, however, is a general (although cautious)
optimism that the environmental impacts of western strip mining, both during and
after mining, can be reduced to acceptable levels by suitable planning and operating
technologies. In short, mined lands can be reclaimed. Reclamation as an add-on
technology will no longer suffice. Rather, environmental factors must be considered
during premining planning; reclamation must be an integral part of the mining
process. This fact manifests the realization that the environment is best protected by
designing (and using) new mining technologies (methods and equipment) that
consider reclamation objectives as well as production goals. Such technologies cannot
be developed solely by mining engineers nor solely by geologists, hydrologists, and
agricultural scientists. Instead, an interdisciplinary approach is necessary.
Oil shales occur in both the western and eastern parts of the country in large
volume. Estimates of the recoverable shale oil run into the hundreds of billions of
barrels. Recently, western oil shales have received considerable attention due to
renewed commercial interest as well as government sponsored research and
demonstration projects.
172
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OIL SHALE SURFACE
MINING
Western oil shale is actually a marlstone containing an organic material known
as kerogen. In order to extract the oil, the rock must be heated to temperatures
above 450° to 550° C, causing the kerogen to undergo pyrolysis yielding an oil
product. Various mining methods have been devised to extract or prepare the oil
shale for retorting.
Large scale open-pit mining was originally proposed for federal oil shale lease
tract "Ca" in support of a commercial size retorting operation. The scale of the pit
would be comparable to large copper and iron ore mines. Environmental problems
could include large scale temporary disruption of the local environment, destruction
of groundwater aquifers, fugitive dust, and reclamation associated with open pits. In
addition, water requirements for dust control and revegetation could be extensive.
SHALE IN SITU
MINING
URANIUM EXTRACTION
Large scale room and pillar underground mining has been proposed by several
potential commercial developers including Union, Colony, Superior, and Paraho. The
volume of material mined by underground methods would be substantially less for
an equivalent shale oil production than with the use of open pit mining. The
overburden would not have to be disturbed and the richest kerogen-bearing zones
would probably be selectively mined. Surface disturbance would be far less and
fugitive dust could be more easily controlled than for surface mining. However,
substantial environmental impact may still occur to the groundwater system. Caution
not to vent fugitive dust to the atmosphere must be taken. Mine drainage must be
properly controlled and the retorted shale disposed of in an acceptable manner.
Surface subsidence or fracturing between aquifers could occur unless the mine
geometry was carefully engineered to avoid these problems.
True in situ mining involves heating the shale inplace in the ground and
extracting the oil through boreholes without employing conventional mining
methods. Modified in situ mining differs from true in situ in that conventional
underground mining techniques are used to remove approximately 20-25 percent of
the rock in order to rubbilize the shale and retort the remaining shale in the
ground. Both processes involve a mineral preparation phase in which permeability to
air flow in the shale is increased by explosive fracturing or through the use of fluids
or gases under pressure. The environmental impact of these mining methods may at
first appear to be the least of any method since most of the waste is left
underground. However, true or modified in situ mining necessitates retorting within
the ground and hence the associated risk of groundwater contamination by leachates
from the retorts. At the same time the retorts themselves and the fracturing
necessary to achieve retort permeability may interconnect different aquifers reducing
groundwater quality. Surface effects such as subsidence, gas leaks, and thermal
pollution have not been assessed for these methods.
Tar sands are rock materials, usually sand or sandstone, which have part of the
void space filled with viscous hydrocarbons. It has been proposed to mine tar sands
by using either surface mining or in situ methods. Most U.S. tar sands occur in
Utah where the environmental impacts of mining would be much the same as for
western oil shale development. In terms of commercial interest and available
technology, the tar sands industry seems well behind the oil shale industry.
Environmental solution found for the oil shale industry may later be applicable to
the tar sands industry.
There are three primary mining methods that are used to extract uranium.
These are surface mining, underground mining, and in situ leaching also known as
solution mining. Regardless of the mining method used, several environmental
problems are associated with the extraction of uranium.
The uranium content in extracted ore is approximately 0.2 percent. The
remaining 99+ percent of the extracted material becomes waste spoils or tailings
which require proper disposal. The open air storage of the spoils produce
opportunities for substantial fugitive dust emissions. In situ mining of uranium using
a leaching process risks the contamination of surface and groundwaters by the
leachate. The mining of uranium, therefore, has the potential to produce air, water,
and solid waste disposal problems.
173
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FUGITIVE DUST
Most fugitive dust production in uranium extraction results from surface
mining activities. Removal of topsoil and overburden, blasting, and hauling of
overburden and ore are the activities most responsible for generating fugitive dust.
The environmental impact of fugitive dust generated by uranium extraction is
considered most serious in areas adjacent to the mines. The dust emitted to the
atmosphere is predominantly silica, with trace quantities of uranium, thorium, and
sulfates. Additional compounds and elements associated with the soils and ores of a
particular area may also be present. Though it produces a small total impact, dust is
easily picked up by moving water, thereby contributing to surface water
contamination.
URANIUM MILL
TAILINGS
FEDERAL/STATE
REGULATIONS
The in situ recovery process for uranium has existed for several years but has
recently experienced a rapid growth. Increased costs associated with surface and
underground mining have now made the in situ method economically competitive.
Typically, in situ uranium mining is initiated by drilling five holes, four of
which are approximately 50 feet apart in the form of a square. Centered inside the
square is the fifth hole. A leaching solution is injected into the four corner holes by
use of a pumping mechanism. The uranium in the ore body is dissolved into the
leaching solution. The uranium containing solution is pumped upward through the
fifth hole and is recovered at the surface. The rate of solution extraction exceeds
the rate of solution injection. This facilitates a continuous flow and minimizes the
likelihood of solution back up and escape into the groundwater. The uranium is
extracted from the solution, allowing the solution to be recycled. Holes are drilled
on the periphery of the five-hole solution mining system in order to detect, and
thereby minimize, the escape of the leaching solution into the groundwater.
The major environmental problem associated with solution mining is the
potential loss of leachate which could result in the contamination of both
groundwater and surfacewater. The opportunity for contamination arises not only
through the natural mixing of the leachate with the groundwater, but also from the
active migration of the solution in both horizontal and vertical direction. The
magnitude and effect of such losses are unknown at the present time, but the
possibility certainly exists. Where ammonium carbonate is used as the solubilizing
agent, groundwater pollution from nitrates may occur. It is not yet clear if the
extracted area can be totally reclaimed by a flushing process.
In 1974, over six million metric tons of uranium mill tailings were generated.
The tailings consisted of approximately 80 percent sand and 20 percent slimes.
Tailings created by the processing of uranium ore are discharged to tailings ponds
for disposal. Here, solid wastes settle to the bottom of the pond and any liquids
present are recycled, evaporated, or infiltrate into the ground. Excess liquid is
discharged to surface streams. From an environmental standpoint, complete recycle
appears the most beneficial method. However, some milling practices preclude large
scale recycling because of the buildup of undesirable constituents in and around the
tailings pond. Several environmental problems may result from the tailings pond
method of discharge. Tailings may contain such contaminants as radioactive
materials, nitrates, sulfates, organic chemicals, and toxic trace elements. Water
percolating through the tailings may pick up these contaminants, carrying them to
ground and surface waters. Studies in New Mexico have shown that groundwaters
have become contaminated by selenium contained in tailings ponds. This problem is
most severe when tailings ponds are constructed in permeable soils. The use of a
clay sealant and other pond liners which will retard the flow of water into the
ground offer some control over groundwater contamination.
There are state and federal regulations that directly impact the mining of
energy producing materials. The most significant of these regulations directed toward
environmental regulation are summarized in the following paragraphs.
The Environmental Protection Agency is currently identifying and must report
to Congress on those facilities defined under Section 169 of the Clean Air Act
Amendments of 1977 as major emitting facilities. This definition applies to facilities
with the potential to emit 250 tons per year or more of any air pollutant which
could contribute to deterioration of air quality. The report to Congress will also
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UNDERGROUND INJECTION
CONTROL PROGRAM
examine the air quality benefits of including such a facility in the category of a
major emitting facility as well as administrative aspects of regulating such a facility.
Mill tailings and associated mining and milling facilities that are considered major
emitting facilities will be subject to fugitive dust control by Best Available Control
Technology (BACT). However, it is envisioned at this time that fugitive dust
emissions will not be subject to an air quality assessment to determine the
increment of air quality that these emissions consume.
Where the effluent from a tailings pond is disposed of by underground
injection or where the effluent is pumped to a shaft or worked out mine area for
disposal in the ground, that effluent will be subject to the underground injection
control (UIC) program. The requirement for the underground injection control
program appears in Section 1421 of the Safe Drinking Water Act 1974. The
proposed regulations dealing with UIC, which first appeared for public comment in
the Federal Register in 1976, have since undergone extensive revision.
The Federal Water Pollution Control Act (FWPCA), Section 307, requires that
the Environmental Protection Agency publish and periodically update a list of toxic
pollutants. These pollutants are to be subjected to effluent limitations based upon
the application of Best Available Technology Economically Achieveable (BATEA).
Prior to June 1976, the Environmental Protection Agency had devoted little time to
establishing effluent limitations for toxic substances in water. However, on June 7,
1976, the Environmental Protection Agency signed an agreement which settled four
lawsuits brought against the Agency by the Natural Resources Defense Council and
the Environmental Defense Fund. These suits were aimed at forcing the Agency to
expand the list of toxic substances to be regulated under Section 307(a) of the Act,
to promulgate final 307(a) standards which had been previously proposed, and to
promulgate previously proposed pretreatment standards. In reaching a settlement, the
Agency agreed to promulgate 307(a) standards for six of the nine pollutants for
which standards had been proposed previously and to complete rulemaking for
existing sources of pretreatment standards for eight industrial categores. However, in
exchange for expanding the 307(a) list and for near term promulgation of additional
pretreatment standards, the Agency agreed to review and revise by the end of 1979
best available technology (BAT) standards for 21 industrial categories, including the
coal industry, with a primary focus on a list of 65 toxic or priority pollutants.
PRIORITY POLLUTANT LIST
The Settlement Agreement list of 64 toxic or priority pollutants was composed
of compounds and classes of compounds. These classes were then expanded into
sublists of specific representative compounds to remove any ambiguities in the study
efforts. Thus, the toxic or priority pollutant list actually contains a total of 129
chemicals (114 organics, 13 heavy metals, cyanide, and asbestos). A list of the
organic pollutants found in coal mine drainage is shown in table 2.
The Ore Mining and Dressing and coal industry are in the group that must
have effluent limitation standards by December 1979. The Effluent Guidelines
Division is undertaking research to examine treatment of tailings pond liquors from
uranium mills, assuming all ponds are lined. This research will examine the
economic, environmental, and technical aspects of (1) total containment, (2) recycle
of liquor, and (3) effluent release following best practical treatment. In the latter
case those pollutants identified in the consent decree will be addressed.
BEST MANAGEMENT
PRACTICES
Recent amendments to the Federal Water Pollution Control Act have extended
compliance by industry in meeting effluent limitations to 3 years. The 1972 Act
had set compliance at 1 year after effluent limitations were established.
Section 304e of FWPCA allows the Administrator to publish regulations (Best
Management Practices) to control non-point sources of toxic or hazardous pollutants.
Such Best Management Practices (BMPs) will supplement any effluent limitations for
a class or category of point sources. These BMPs will apply to control of plant site
runoff, spillage or leaks, and drainage from raw material storage. However, it must
be determined that these pollutant sources are associated with the industrial
manufacturing or treatment process within such categories or classes of point sources
and that significant amounts of such pollutants are contributed to navigable waters.
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WASTE TREATMENT
MANAGEMENT PLAN
FEDERAL AND STATE
PROGRAMS
NEW MINING LAW
Definition of BMPs is also being undertaken by the Effluent Guidelines Division of
EPA and it is envisioned that tailings will be subjected to Best Management
Practices.
The Federal Water Pollution Control Act, in particular, Section 208 of that
Act, requires the preparation and implementation of a areawide waste treatment
management plan. This plan is developed for areas which have been identified by
the Governor of a State for exhibiting substantial water quality control problems.
While the Act is relatively broad in specifying what the areawide plans shall contain,
it specifically references the need for a process which would identify mine related
sources of pollution and methods to control those sources of pollution. The plan
also requires the development of a process to control deposition of wastes which
could effect water quality in the area and a process which would control the
disposal of pollutants on land or in subsurface excavations in order to control
ground and surface water quality.
The Resource Conservation and Recovery Act (RCRA) will subject mining
waste, for example, tailings, to a rigorous study. Specifically, Section 2008f requires
that a "comprehensive study of the adverse effects of solid waste from active and
abandoned surface and underground mines on the environment be performed." This
study will examine the effects of solid waste on humans, water, air, health, welfare,
and natural resources. The study will also examine the adequacy of currently used
measures to prevent or reduce the adverse effects of mining wastes. The study,
currently under contract, will specifically analyze:
• The source and volume of discarded material generated per year from
mining.
• Present disposal practices.
• Potential dangers to human health and the environment from surface runoff
of leachate and air pollution by dust.
• Alternatives to current disposal methods.
• The cost of those alternatives in terms of the impacts on the mine products
costs.
• Potential for use of discarded material as secondary sources of mine
product.
The Act also requires the Administrator of EPA, as he deems appropriate, to
review studies and activities of other agencies dealing with mining waste in order to
avoid duplication of effort.
If no actions are taken by the federal or state governments to control
subsidence problems from future mining, then it is likely that present problems will
be compounded and eventually remedial action will become necessary by government
agencies. A 1976 U.S. Bureau of Mines report indicated that four backfilling
demonstration projects were currently in progress for abandoned mine subsidence
control with an estimated cost of $7 million. The U.S. Bureau of Mines estimates
that it will be involved in three to five subsidence control projects (for abandoned
mines) per year for the next 5 to 10 years. Presently there is no federal program to
control creation of future subsidence problems. Only one state, Pennsylvania, has
enacted legislation specifying the separate responsibilities of surface owners and mine
operators for subsidence damage. Under Pennsylvania law, which applies only to the
bituminous fields, a mine operator is responsible for damage to surface structures
that were in existence prior to implementation of the law (1966). Surface structures
built after 1966 in subsidence-prone areas can be protected by purchasing coal
support from the mine operator.
The new surface mining law. Public Law 95-87, of August 3, 1977, addressed
the subsidence problem in a general manner under Section 516(b)(1) which states in
part.
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SURFACE MINING ACT
FUTURE COAL NEEDS
SUBSIDENCE DAMAGE
CONTROL
"Each permit issued under any approved State or Federal program
pursuant to this Act and relating to underground coal mining shall
require the operator to-adopt measures consistent with known
technology in order to prevent subsidence causing material damage to the
extent technologically and economically feasible, maximize mine stability,
and maintain the value and reasonable foreseeable use of such surface
lands except in those instances where the mining technology used
requires planned subsidence in a predictable and controlled manner:
Provided, that nothing in this subsection shall be construed to prohibit
the standard method of room and pillar mining."
In order to adequately address the subsidence problem, a concerted effort is
needed by all levels of government (federal, state, and local) to coordinate the
surface development with the extraction of the coal so that maximum use can be
made of each resource without conflicting with development of the other.
On December 13, 1977, the Department of the Interior, Office of Surface
Mining Reclamation and Enforcement published in the Federal Register a set of
interim rules and regulations titled the "Surface Mining Reclamation and
Enforcement Provisions," more commonly known as the surface mining act. Some of
the major sections of these rules and regulations are general and specific
performance standards for the surface mining of coal, general performance standards
for underground mines, and a program that will allow for the reimbursement to
states to assist them in meeting the standards of this Act and to encourage the
states to build strong reclamation and enforcement programs.
A great deal of controversy arose following the publication of this Act. Much
of the discussion centered on the design criteria for sedimentation ponds and
temporary diversion structures. As a result of these objections, the Office of Surface
Mining Reclamation and Enforcement issued on February 27, 1978, Interim Final
Rules and Notice of Public Hearing. These rules modify the design criteria for
sedimentation ponds to allow for greater flexibility and to accommodate more
diversity of the terrain and other physical conditions.
Work is presently ongoing to develop the final rules and regulations for this
Act. It is anticipated that they will be published in the Federal Register in the fall
of 1978.
There have been many estimates made as to the amount of coal that will be
required in the future. These range from only a minor increase up to those who feel
that coal production will more than double by the year 2000. All agree that coal
production must increase. The source of this increased production will come from
two major sources—eastern underground coal mines and western surface mines.
Eastern surface mines will continue to supply large amounts of coal. However,
recent improvements in mining techniques such as haul back, mountaintop removal
and valley fill, and the new surface mining act should significantly reduce the
environmental problems created by surface coal mining.
The problems are not so simple for underground coal mining. One of the most
significant problem is that created by subsidence.
Although there is no simple or universal solution to all of the problems caused
by subsidence, various means are available to control surface damages from future
mining. Two basic approaches must be coordinated and applied to each situation.
The first approach involves controlling the mining activity while the second involves
controlling the nature of surface development. The specific subsidence damage
control measures most suitable depend upon the extent of surface development that
would be threatened by subsidence. For a heavily built up area underlain by
mineable coal, the subsidence control measures must be aimed at preventing surface
subsidence by controlling the mining operation to minimize surface disturbance. For
nondeveloped areas the emphasis must be placed upon delaying surface development
until the coal resource is extracted and the area has undergone subsidence and
stabilized.
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Future mining of high and medium density development areas in a manner
which would result in future subsidence could have a major economic impact which
would be unacceptable in terms of both individual impact and impact on the general
welfare of the community. Mining technology presently exists which would generally
permit recovery of approximately 50 percent of the coal while substantially reducing
surface subsidence.
SURFACE SUPPORT
Conventional room and pillar mining can be modified to provide surface
support in many cases by accepting much lower extraction ratios with careful
attention to design, size, and spacing of support pillars. This method has been used
successfully in Western Pennsylvania where present law requires the mine operator to
provide surface support for some structures. Panel and pillar mining likewise can
be adapted to minimize subsidence damage and is compatible with longwall mining.
Shortwall mining techniques can also be adapted to provide surface support. The
critical considerations in utilizing these methods involve abandonment of adequate
coal for support (about 50 percent), adequate pillar size so that deterioration of
pillars will not cause subsidence, and careful design of pillar placement to sup;ort
the overburden. Other techniques have been proposed to reduce the impact of
subsidence by minimizing the compressive and extensive strains that do most of the
damage. These methods include extraction face control measures to control the
propagation rate of the subsidence trough and harmonious extraction methods based
on the principal of overlapping compressive and extensive strains to achieve a
cancellation effect. In addition, various backfilling measures such as hand packing,
mechanical backfilling, hydraulic backfilling, and pneumatic backfilling can be
utilized to reduce the amount of surface subsidence. Although backfilling may
appear to be an attractive subsidence control measure, the high costs involved, at
least one to four dollars per ton of coal mined under favorable conditions, pose a
serious question of economic viability.
LAND OWNERSHIP
AND RIGHTS
Although methods exist to permit mining of a portion of the coal under
developed areas without inducing subsidence, it it not likely that mine operators will
voluntarily abandon a large percentage of their mineral resource unless they are
required to provide surface support. The key to the problem is the recognition that
land ownership and rights can be divided into three estates: surface rights, mineral
rights, and surface support rights. Each of these can be held in separate ownership.
Unless the surface property owner is assured the right of surface support it is likely
that future mining under developed areas will produce substantial damage similar to
that which has occurred in the past. If the mine operator must provide surface
support then approximately 50 percent of the mineral must be abandoned which
raises a key policy issue in terms of meeting the Nation's energy needs.
UNDEVELOPED COAL AREAS
For situations where mineable coal exists under sparsely or undeveloped areas
the solution is simpler in concept but may prove equally difficult to implement.
Future development of these areas should be controlled to preclude high or medium
density development which may be subjected to future subsidence. It is
recommended that, prior to approval of any surface development in areas underlain
by coal, the potential for future mining and subsequent subsidence be reviewed. It is
suggested that, in areas where mineral rights have been severed from the property
rights, the property owner should be required to certify the specific status of the
rights to surface support prior to subdivision or land development for which any
state or local permit may be required.
Just as it is impractical to allow development to occur in areas where future
mining may present a real threat of subsidence, it is equally impractical to consider
that mining should be allowed to occur in a manner that the resultant subsidence
potential is of a nature which cannot be defined in terms of time and extent.
Regulation of the mining industry should be established which will avoid the
creation of a potential subsidence problem. The principal problem presented with
regulation of development in such cases is that it is presently impossible to predict
when subsidence may occur. This precludes development of the land for an
extended period unless very expensive stabilization measures are implemented. Two
general approaches to mining techniques should be considered.
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TWO GENERAL TECHNIQUES
OTHER POTENTIAL
PROBLEMS
WESTERN & EASTERN
PROBLEMS DIFFER
ALASKAN COAL PROBLEMS
• Mine in a manner that will not cause immediate or long-term subsidence
problems.
• Mine in a manner which would result in immediate and complete
subsidence.
Under the first approach it would probably be necessary to limit extraction to
50 percent or less, based on current generally accepted engineering principals. Under
the second approach of total extraction or near total extraction, it would be
necessary to ensure that the surface is left in or returned to a usable state.
Flexibility in such regulation must, however, be maintained since physical problems
may exist which would preclude implementation that would achieve the desired
result. Trade-offs and alternative approaches must be accommodated to effectively
deal with individual case situations.
There are a number of other potential environmental problems that could
develop due to underground coal mining. Drift mines, particularly those operating up
the dip of the coal seam, have the potential for producing large amounts of acid
mine drainage. This drainage does not necessarily drain out through the mine
opening where it would be necessary to treat it. Some can build up in the
abandoned workings and by moving down the interface between the coal and
surrounding strata, find its way to the surface of the hillside as seeps and
contaminates surface waters.
Underground mining operations, due to their high initial capital investment, ';
must be extensive in order to provide the operator with a profit. Large underground
openings can intercept numerous groundwater aquifers. These aquifers could be
major sources of municipal water supplies. Even though the water would be pumped
to the surface so that it could again enter the water supply, its quality could be
significantly reduced.
As the coal sources near the surface become more depleted, it will become
increasingly necessary to mine coal from much greater depths. The discharges from
these mines could contain greater quantities of TDS than the discharges of mines
located nearer the surface. This is caused by the greater thickness of overburden
that the water would percolate through.
Many of the environmental problems associated with western coal mining are
significantly different than those encountered in the east. These differences are
caused by major variations in both the climate and in the soil conditions.
Most of the coal mined in the western United States is found in semi-arid or
arid areas. The result is that fugitive dust is a much greater problem in the west
than in the east. Haul roads produce large amounts of dust both from the. normal
traffic and naturally by the windy conditions that are often encountered. This
problem could become increasingly important as more and more mines open within
a relatively small area.
In many cases, western coal seams are major aquifers. Utilizing the methods
presently used to extract western coal, i.e., large area type operations, aquifer
disruption could become a serious problem. Methods need to be devised -whereby
the aquifer could be restored with"no resulting loss in groundwater quality.
The soils in the west are generally alkaline rather than acidic; therefore, AMD
is generally not a problem in the west. However, the alkalinity does cause its own
type of environmental problem. The salts in the soil are very soluble. As the
overburden is broken and overturned, these salts become very susceptible to
leaching. The salts become concentrated, seriously contaminating the water with
TDS. This water can become so brackish, that it is no longer useful, even for
irrigation.
The potential environmental problems associated with Alaskan coal could be
immense. The mineable reserves in Alaska are tremendous. It has been said that the
Alaskan coal reserves outstrip all those in the lower 48 states combined. Much of
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•t,
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UNDERGROUND
COAL GASIFICATION
the coal in Alaska is not flat lying but rather is steeply dipping. This alone can
create numerous problems. Very little is known concerning the effects that mining
will have on the permafrost and tundra. It appears certain that new mining methods
will have to be developed to protect the fragile Alaskan environment if this coal is
to be developed in an acceptable manner.
Advancing technology can create new or different environmental problems. It
is likely, that in the future, in situ coal gasification may become a significant source
of energy. A detailed description of the various underground coal gasification
processes being investigated is beyond the scope of this paper. However, all processes
follow the same general procedure. Contact with the coal seam is made by drilling
several boreholes from the surface. The permeability of the coal seam (to air flow)
is then increased, and the seam is ignited and burned within a controlled
temperature range, causing pyrolysis of the coal and release of the product gases.
Air or oxygen must be injected through boreholes to support the combustion, while
product gases are generally removed through separate boreholes. EPA is presently
involved in supporting research to determine the possible environmental effects of
underground coal gasification. At the present time the major environmental
implications of underground coal gasification involve the following:
SURFACE DISPOSAL
URANIUM EXTRACTION
PROBLEMS
182
• air emissions
• groundwater pollution
• subsidence
• thermal pollution
For any of the mining methods, the disposal of spent or processed shale must
be considered since essentially all of the shale mined ends up as a spent shale
disposal problem. Possibilities for disposal include surface disposal in huge mounds
or as valley fills, returning the spent shale to the mine (surface pit or underground
mine) or in the case of modified in situ, slurrying the surface retorted spent shale
for reinjection into the retorts.
Surface disposal of spent oil shale is probably the most commonly postulated
disposal method. However, numerous environmental problems must be solved. The
spent shale must be cooled, transported to the disposal site, and properly contoured.
These activities are capable of producing substantial quantities of fugitive dust unless
proper control measures are taken. Once in the disposal area, the shale must be
compacted and eventually revegetated. The shale must be leached to remove the
salts and/or covered with a sufficient depth of soil to prevent the roots from
reaching the spent shale. EPA studies on revegetation of oil shale indicate that
problem areas that may be encountered include inadequate leaching of salts prior to
planting, resalinization due to the upward movement of salts into the soil cover,
initial high pH on the shales, saline runoff from revegetated shale, and the
concentration of some toxic trace elements in the vegetation. In addition, a hazard
exists for contamination of surface and groundwaters by leachate from the spent
shale. One EPA study has indicated that the permeability of spent shale, even
though it has been compacted, may be rather great. This result is much different
from the early predictions that after compaction the spoil would be impermeable.
Disposal of spent oil shales in underground mines eliminates the revegetation
problem but may increase the risk of contaminating groundwater supplies. Very
detailed studies of the specific disposal site would be necessary to determine the risk
of water leaching through the spent shale and moving into the groundwater system.
Disposal of spent shales by reinjection into the modified in situ retorts may
complicate an already serious pollution question. Modified in situ retorts, as
commercially proposed, intersect several permeable zones in their 300- to 7,000-foot
height. Addition of surface retorts shale waste may increase the production of
leachates which has ready access to the groundwater flow system. Once in the
groundwater system the contaminates may also affect surface streams which are fed
by groundwater recharge.
Uranium extraction in the future will present environmental problems of
greater magnitude than present extraction unless adequate control technology is
-------
GROUNDWATER CONTAMINATION
COAL EXTRACTION R&D
GROUNDWATER POLLUTION
RESEARCH
developed. The rising price of uranium ore will make profitable the extraction of
lower grade ore. Exploitation of the lower grade ore implies that more waste spoils
and tailings will be generated per unit of ore mined. The increased wastes may
produce several detrimental effects on the environment. More land will be disturbed
to produce a given amount of uranium. The potential for fugitive dust emissions will
increase due to the increased production of spoils and tailings. The proper disposal
of solid wastes will require finding sufficient suitable disposal sites and/or
reclamation methods to handle the increased tailings and spoils.
Groundwater contamination may become a future problem in areas surrounding
uranium mines if in situ mining and underground waste injection become more
common. As stated earlier, losses of the leachate used in in situ mining occur due
to dilution and mixing with groundwaters. Mixing introduces the opportunity for
groundwater contamination by such leaching compounds as sulfuric acid and
ammonium carbonate.
Several uranium mills presently dispose of toxic liquid and chemical wastes by
deep well injection. These wastes result either from excess liquid that has not
evaporated in the tailings ponds or from waste regenerant solutions used by in situ
mining operations. The disposal zone is usually several hundred feet below the
surface. It should be separated from aquifers by impermeable formations to prevent
contamination of groundwaters. Little is known about the long-term impacts on
groundwaters due to deep well injection. Wastes disposed of in this manner typically
have high concentrations of dissolved solids and contain toxic heavy metals such as
molybdenum, arsenic, selenium, and uranium. Contamination of aquifers from
injected wastes appears to have occurred in New Mexico. The injection of these
toxics into the ground presents a real, though presently uncertain, threat to
groundwater near the injection site.
The Extraction Technology Branch of the Industrial Environmental Research
Lab, Cincinnati, is involved in research that seeks to minimize the environmental
disturbances associated with the extraction of coal. Disturbances related to coal
extraction include air and water pollution and production of solid wastes. A number
of the research programs deal with the development of environmentally acceptable
methods for mining coal. Projects are underway that will assess mountaintop
removal, head-of-hollow fill, steep slope, surface longwall, modified block-cut, and
daylighting mining methods.
Other research projects are evaluating various sediment control techniques.
These include a project to demonstrate the effectiveness of debris basins and to
demonstrate methods to reduce sediment that is generated from haul roads. Another
project is applying current technology to improve techniques for surface mine
sediment control. The use of a vegetative filter zone to control fine grained
sediments is being evaluated.
Four projects are evaluating techniques to minimize groundwater pollution.
One project is evaluating the feasibility and effectiveness of using gravity connector
wells to improve stream quality by reducing groundwater drainage from abandoned
underground coal mines. Another project will assess the economics of intercepting
groundwater inflow into an active coal mine, with emphasis on reducing the amount
of acid mine drainage. The third project is to establish criteria to locate sources and
define the quantities of water that will enter underground coal mines through faults,
fractures, etc. The final project will determine the potential for underground coal
mines to pollute the groundwater in the vicinity of mining operations. The study
will involve detailed evaluation of groundwater conditions as selected sites.
In order to avoid duplication of efforts and to help inform interested persons
regarding oil shale research in progress, the working document entitled, "Oil Shale
Research Overview" was prepared. The May 1977 edition of this document lists 148
federally-funded oil shale research projects of which 73 are being funded by various
EPA offices. The Research Triangle Park Health Effects Research Laboratory of EPA
is assessing human exposure effects relationships and evaluating hazards to man
under controlled experimental conditions. The Industrial Environmental Research
Laboratory, Cincinnati, supports coordinated, interagency oil efforts by administering
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EPA MONITORING
RESEARCH
FATE OF POLLUTANTS
URANIUM EXTRACTION
PROBLEMS
ZERO & NONZERO
DISCHARGE
an R&D program covering environmental assessment of extraction and process
control technology. Current activity by the EPA Duluth Laboratory includes oil
shale-related fresh eater ecosystem effects. Region VIII of EPA will develop a
comprehensive information profile for major fresh water aquatic environments that
could be affected by oil shale development. EPA interagency participation is
exemplified by the 42 interagency studies listed in the "Oil Shale Research
Overview."
Much of the EPA monitoring research is done at its Environmental Monitoring
and Support Laboratory (EMSL) at Las Vegas, Nevada; Cincinnati, Ohio; and
Research Triangle Park, North Carolina. Las Vegas activities include western regional
air monitoring, groundwater monitoring and techniques development, and overhead
monitoring. Cincinnati EMSL stresses water techniques development and quality
assurance. Research Triangle Park is developing energy-related air monitoring quality
assurance support and air pollutant measurement and instrumentation research.
EPA is studying the fate in freshwaters, groundwaters, and air of specific
pollutants resulting from oil shale development. The Athens Laboratory is studying
the fate of specific pollutants in freshwaters. EPA Region VIM is providing for the
maintenance of an air quality monitoring network to continue to define long
(5-year) baseline data information.
The environmental research and development results for the near term are
expected to be characterization, control technology, assessment and measurement
and monitoring protocols for oil shale development. In situ processing, extraction,
surface retorting refining and combustion are included in current oil shale research
activities.
Currently, the Extraction Technology Branch has only a limited program
dealing with uranium extraction. One project will determine and document for one
uranium-bearing aquifer system the interrelationships between aquifer geometry,
hydrology, hydrochemistry, and mineralogy, and uranium mineralization and to
determine how this natural system will respond to local chemical or physical stresses
induced by uranium mining. Another project is evaluating potential problems of
toxic elements associated with uranium mineralization and mining in South Texas.
A proposed study will evaluate candidate approaches for treatment and/or
disposal of uranium mill tailings that have been discharged to lined tailings pond.
Both nonzero discharge and zero discharge options will be considered. A nonzero
discharge approach to be evaluated is the release of the tailings pond effluent to
surface waters following application of Best Practicable Treatment (BPT) effluent
limiations. Zero discharge approaches that will be evaluated include increasing the
surface area of the tailings pond for increased evaporation and recycling of the
wastewater.
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References
Hill, R., and E. Bates. Acid Mine Drainage and Subsidence: Effects of Increased
Coal Utilization, EPA-600/2-78-068, April, 1978,
Assessment of Environmental Aspects of Uranium Mining and Milling, Battelle
Columbus Laboratory, EPA-600/7-76-036, December, 1976.
Grim, E. Environmental Assessment of Western Coal Surface Mining, Industrial
Environmental Research Laboratory, U.S. Environmental Protection Agency, June,
1976.
Grim, E., and R. Hill. Environmental Protection in Surface Mining of Coal,
EPA-670/2-74-093, October, 1974.
Erosion and Sediment Control: Surface Mining in the Eastern U.S. Volume 2:
Design, Hittman Associates, EPA-625/3-76-006b, October, 1976.
Hill, R. Methods for Controlling Pollutants, Industrial Environmental Research
Laboratory, US. Environmental Protection Agency, August, 1976.
Wilmoth, R., and J. Martin. Neutralization Options for Acid Mine Drainage Control,
Industrial Environmental Research Laboratory, U.S. Environmental Protection
Agency, November, 1977.
Gage, S., and E. Bates. Possible Environmental Implications on In Situ Energy
Development—Coal and Oil Shale, Industrial Environmental Research Laboratory,
U.S. Environmental Protection Agency, December, 1977.
Hill, R. Sedimentation Ponds—A Critical Review, Industrial Environmental Research
Laboratory, U.S. Environmental Protection Agency, October, 1976.
Mentz, J., and J. Warg. Up-Dip Versus Down-Dip Mining: An Evaluation, Skelly and
Loy, Engineers-Consultants, EPA-670/2-76-047, June, 1975.
Hill, R. Water Pollution from Coal Mines, Industrial Environmental Research
Laboratory, U.S. Environmental Protection Agency, August, 1973.
185
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MINED LAND RECLAMATION
HISTORY
Willie R. Curtis
Forest Service
U.S. Department of Agriculture
Many people think of reclamation in terms of establishing vegetative cover.
Reclamation of mined land is much more than that; however, in this paper
reclamation is used synonymously with revegetation.
Commercial surface mining for coal in the United States began in Illinois just
over 100 years ago. Natural revegetation of many of these areas probably began
soon after mining ceased, because natural forces continually operate to vegetate
disturbed land. For example, many of the 10- to 30-year-old coal surface mines in
Alabama have been naturally reforested with loblolly pine and Virginia pine and
now produce more commercial softwood timber than the surrounding unmined
forest land (1).
Although some surface mines have been revegetated by natural means, the
vegetation process can usually be hastened by planting. Among the earliest
documented attempts at reclamation is the seeding of sweet clover on spoil-bank
ridges by the Wayne Coal Company in Ohio as early as 1918. In 1920, several
species of trees were planted on coal mine spoils in Illinois. Shortly thereafter
research was started in Indiana to determine the adaptability of various tree species
to conditions on spoil banks (2).
A formal research program on the forestation of strip-mined land was started
in 1937 by the U.S. Forest Service through its Central States Forest Experiment
Station at Columbus, Ohio (3). Research was conducted in cooperation with the
coal mining industry, state agencies, and agricultural experiment stations. The results
of this early research were summarized by Limstrom (4). It involved mostly the
evaluation of survival and growth of many different tree species. The value of
planting nurse-trees such as black locust and European alder in mixture with other
tree species received much attention. Thousands of acres of surface mined land have
been successfully forested with species and planting procedures recommended by
these early researchers. That research still serves as the basis for many revegetation
guides in use today.
Before the 1960s, most of the research and consequently most of the
reclamation centered on tree species; there was little concern for erosion and
sedimentation. Anyway, most of the sediment from erosion on the ungraded spoil
dumps was trapped in the depressions between the mounds. Herbaceous cover was
considered a hindrance to the establishment and growth of planted tree seedlings.
Beginning in the early 1960s more and more emphasis was given to the quick
establishment of herbaceous cover for erosion control and for esthetic purposes. This
new emphasis was coincident with greatly expanded surface mining activity in the
Appalachian region, where water runoff and erosion produce severe sedimentation
problems. Subsequently, the use of herbaceous vegetation for ground cover and
erosion control increased to the extent that for the past 10 years or so relatively
few trees have been planted. Diversified plantings of grasses, legumes, shrubs, and
EARLY RESEARCH
HERBACEOUS COVER
187
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RECLAMATION TECHNOLOGY
SPOIL DIFFERENCES
WEATHERING PROCESSES
tree species are still needed to provide for a variety of future uses of the land,
Reforestation is anticipated as a result of natural plant succession in much of the
eastern United States, especially where an herbaceous cover is established for erosion
control without further management.
As early as the mid-1940s some research on the use of herbaceous species in
reclamation was reported (5). Subsequent trials and other research have been
conducted by the Forest Service, Soil Conservation Service, Agricultural Research
Service, and various state experiment stations. The results of these experiments have
been incorporated into revegetation guides published by federal, state, and private
agencies.
Many plantings have been made by industry-related groups such as reclamation
associations and coal producers' associations, and by many individual mining
companies. These plantings may also be used in evaluating reclamation success.
Reclamation technology has made significant advances in the last 30 years with
the most rapid developments coming during the past decade. Accomplishments have
come about through the joint efforts of the many concerned individuals representing
governmental, educational, and industrial interests. Acceptance of environmental
issues as priority national problems permitted enactment and revision of laws
regulating surface mining activities. Increased interest led to increased appropriations
which permitted expansion of research relating to mined land reclamation.
Reclamation should begin with an evaluation of the overburden, including all
soil and rock above the coal seam. In addition to economic and legal factors,
chemical, physical, and biological factors must be considered in planning reclamation
procedures. Acceptable reclamation usually means burial of undesirable overburden
material in the spoil bank and adequate protection of the affected area from
siltation, chemical pollution, and mass failure.
The chemical and physical properties of spoil determine the magnitude of the
reclamation effort needed and the degree of success that can be attained. Some
spoils require only grading and minimal treatment to allow successful revegetation.
To be productive, others require many tons of lime and large quantities of mulch or
organic additives in addition to fertilizer. On some spoils, saving and replacing
topsoil is the best way to restore productivity. Surface water pollution resulting
from severe erosion and movement of acid and soluble salts into streams is also a
serious problem in surface mining. Mass failure of spoil banks can completely negate
previously successful reclamation efforts, for landslides often occur after spoil
grading and revegetation have been accomplished.
Society has had long and successful experience in dealing with earth surface
materials. However, there are extremely important differences between these
materials and the typical spoil. Unlike normal agricultural soils, most mine spoils are
made up of freshly broken rock fragments. A reclamation plan not only has to deal
with this material as it is now, but also of even greater importance, must consider
what the material will become in the future as weathering reactions progress. The
nature of these reactions profoundly influences all aspects of the reclamation effort.
If chemical processes do not provide nutrients of sufficient quantity and
quality for plant growth, fertilizer must be applied. If, on the other hand, these
reactions produce excessive acidity or toxic elements, appropriate amendments must
be utilized. Water-soluble products can enter the surface and ground water of the
area. Particulate matter formed by both physical and chemical breakdown of large
fragments is highly erodible and may cause severe siltation in nearby streams.
Engineered spoil banks and slopes may become unstable because of changes in the
properties on which their initial design was based.
The nature and extent of the weathering processes and the time required to
reach relative equilibrium with the surface environment depend on such
characteristics of overburden strata as mineralogy, geochemistry, fabric, and texture
as well as upon methods of handling and placing the excavated materials. Many
188
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CHEMICAL ANALYSIS
PHYSICAL FACTORS
FINE SPOIL PARTICLES
materials found in sedimentary rocks are chemically unstable in the earth s surface
environment. Pyrite, a common mineral in coal-bearing sediments, is one of the
more important of these unstable materials, for the oxidation of pyrite forms
soluble iron salts and sulfuric acid. This is the major source of acid mine spoil and
acid mine drainage. In addition, these highly acid solutions can break down other
minerals that are resistant to weathering. A common result is high concentrations of
soluble aluminum and manganese. These are notoriously toxic to most vegetation. In
some areas, toxic levels of heavy metals such as copper, nickel, and zinc are also
produced (6).
Chemical analyses can be used to determine the elements present in the strata
from which spoil is formed. However, simply because an element is present does not
necessarily mean that it will become available after disturbance of the overburden;
consideration must be given also to such factors as its mode of occurrence and its
potential to react with other weathering products. These factors can be evaluated by
correlation of chemical analyses with petrologic analyses. A petrologic analysis
should include at least determination of mineralogy, porosity and permeability,
grain-size, and fabric. Knowledge of these characteristics along with the inorganic
and organic geochemistry of the overburden will enhance the ability to predict
weathering reactions as well as the mobility and concentrations of elements of
interest after exposure of overburden material in spoil banks (7).
Studies of heavy metals in spoils have indicated that sedimentary organic
material may play an important role in both the physical and chemical properties of
spoil. It is generally accepted that organic matter is vital in the development of
fertile soil, but to date, investigation of fossil organic matter in overburden as a
source of such beneficial material in .spoil has been totally neglected. The sediments
comprising coal overburden contain various amounts of organic matter. Because of
its pronounced capacity for absorption, cation exchange, and formation of
organic-metal complexes, this organic matter strongly affects the trace metal
assemblage of the sediments of which it is a part (8,9,10,11). It is probable that
this organic matter influences the reactions and mobility of these elements during
weathering of the enclosing rock and therefore affects both stream pollution and
plant growth.
Physical factors affecting success of reclamation are commonly related to color
and particle size of the spoil. Color of the materials directly influences spoil
temperatures through the absorption of solar energy. High temperatures can impede
seedling emergence and alter the growth of surviving plants. Temperatures on the
surface of dark-colored spoils may become so high that plant tissue contacting spoil
fragments is killed. The upper 15 cm of black shales may have temperatures up to
10 C higher than light colored spoils on south facing slopes. Surface temperatures as
high as 64°C were measured in Pennsylvania (12).
Emergence of some grasses is stopped at a soil temperature of 47°C while
others may withstand temperatures to 52°C (13). Once a vegetative cover is
established, the tendency toward excessive soil temperatures is moderated. Mulch can
be used effectively to regulate surface temperatures.
The physical characteristics of mine spoil as a rooting medium are frequently
quite different from those of naturally developed soils. Spoil is an unorganized mass
of material derived from any or all of the strata overlying the coal bed. Particle size
affects soil aeration and moisture efficiency. Thus, it is an important consideration
in reclaiming surface mine spoils.
The proportion of fine particles (less than 2 mm in diameter) varies among
spoils from about 20 percent to 80 percent by weight (14, 15). Southwestern spoils
commonly contain more than 50 percent clay by volume. Many spoils contain 25
percent to 40 percent fines. Both herbaceous and woody vegetation have been
successfully established on spoil within this range. However, in spoils with chemical
properties that limit plant growth, the coarse spoils yield better growth than spoils
of finer particles because lesser amounts of toxic elements are available from the
smaller surface area of the coarse fragments. Spoils devoid of fine particles in the
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MOISTURE CONDITIONS
SPOIL CHEMISTRY
ADAPTABILITY
surface layers are extremely difficult to vegetate directly with seed. Surface layers of
coarse fragments dry out rapidly.
Fortunately, moisture conditions of many spoils are relatively favorable for
plant growth. Variations in micro-relief may aid in water infiltration and percolation.
Because the moisture conditions are more favorable at some depth below the
surface, it is important to speed the growth of seedlings during cool, rainy periods
so that roots penetrate to depths where moisture is available. In some cases this
means selecting species noted for deep rooting, applying fertilizer to promote rapid
initial growth, and applying mulch to maintain moisture near the soil surface until
seedlings are established.
Some spoils having a high proportion of silt and clay are prone to crusting,
which results in a pavement-like surface. This compact surface layer must be broken
before seeding.
Bulk densities of spoils are frequently higher than those of adjacent
undisturbed soils. However, in time, densities will become more favorable to
vegetation growth and development through freezing and thawing, accumulation of
organic matter, and root penetration.
Usually the reclamation specialist does not attempt to correct physical
problems, but, rather, tries to live with them. A premining analysis of the
overburden could be used to schedule movement, mixing, and placement of the
materials so that the most desirable material is left on or near the surface as the
plant growth medium. This applies to chemical as well as physical properties of
overburden.
The chemical nature of strip-mine spoils is extremely variable depending upon
chemical properties of the different strata in the overburden. Some spoils range in
chemical reaction from extremely acid to alkaline. Some are relatively fertile; others
are completely deficient in one or more essential plant nutrients. In the Southwest,
coal mine spoils are normally alkaline, with a pH of about 8.0. They often contain
over 1500 ppm of sodium.
Along with organic matter and nutrients, another prime factor in soil fertility
is the presence of a flourishing and varied population of microorganisms. The
absence of such a micro-flora and fauna in fresh spoil is probably the single most
important deficiency in most areas as far as establishing protective vegetation is
concerned. Therefore, enhancing the establishment of an adequate population of
benefical microorganisms in spoils is very important. It is likely that with proper
placement of overburden strata, fossil organic matter will provide a source of usable
carbon for pioneering species of organisms that can be followed by proliferation of
relatively normal heterogeneous populations.
Microbial associates have been shown to play a key role in establishing plant
species on problem spoils (16, 17, 18, 19). For example, Marx (20) has shown that
pine seedlings planted on acid mine spoils survived and grew well when inoculated
with an ectomycorrhizal fungus, Piso/ithus tinctorius. Rhizobia that will effectively
nodulate legumes can mean the difference between success and failure in vegetating
problem spoils. Some strains of Rhizobium bacteria have been found more efficient
than others in nodulating legumes on mine spoils (21). However, there still are many
voids in our understanding of the microbiological requirements for successful surface
mine reclamation. The conditions listed below are known to be associated with the
mycorrhizal fungi and will help point up the need for continued physiological
investigations of interactions of these symbionts and plant growth and development.
About 95 percent of the world's present species of vascular plants belong to
families that are characteristically mycorrhizal. Of these, about 5 percent are
ectomycorrhizal. The endomycorrhizae are found on the remaining species of
herbaceous and woody plants (22). Ecological adaptability for the above associates is
dependent upon the evolution of metabolic pathways which will enable them to
withstand environmental stress. Of literally hundreds of possible associates which
may be adapted for strip mine reclamation, only a few have been investigated and
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NITROGEN LEVELS
WESTERN RECLAMATION
SPENT SHALE PROBLEM
fewer still have been demonstrated to be useful under such conditions. The more
completely we understand the ecology of mycorrhizal species on adverse sites, the
more intelligent may be our selection and evaluation of species for reclamation.
In the majority of revegetation efforts, either leguminous or nonleguminous
nitrogen-fixing plant species have been used to increase the level of nitrogen in the
spoil material. With few exceptions, isolates that have been examined have shown
the nitrogen-fixing species to be endomycorrhizal as well. In a recent publication on
the interactions between growth, phosphate content, and nitrogen fixation in
mycorrhizal and nonmycorrhizal legumes (23), the mycorrhizal plants showed more
extensive nodulation, increased nitrogenase activity, and higher levels of phosphate in
the early stages of plant development. Later when the significant mycorrhizal effect
on growth was apparent, the total nitrogen and phosphorus per mycorrhizal plant
were also higher. But nitrogenase activity and phosphate content as measured on a
dry weight basis showed no significant differences between mycorrhizal and
nonmycorrhizal plants. The mycorrhizal enchancement of phosphate uptake and
nitrogen fixation apparently precedes the favorable effect on growth. Studies of this
nature would be extremely valuable to our understanding and evaluation of
nitrogen-fixing species for reclamation.
Symbiotic associates of herbaceous species help increase plant yields which, in
turn, have the desirable effect of adding organic matter to the spoil. The
mycorrhizal associates contribute a large fraction to the soil biomass and aid in the
establishment of a microbial succession that performs vital functions in the carbon
cycle. Under the new regulations, mulch is to be used on all regraded and topsoiled
areas. The favorable growth conditions obtained by Vogel (24) using bark mulch as
an aid to plant establishment indicate that various types of vegetative residues
should be investigated in conjunction with degradative and/or cellulose-modifying
microbial species. Many of the successional species are capable of cellulose
degradation and an increase in their populations would aid in the creation of a
nutrient-rich fraction from the vegetative residues.
Reclamationists in the west face some problems quite different from those in
the east. Scarcity of water is of major consequence, but spoil chemical
characteristics are important, too. Many western spoils are high in exchangeable
sodium and salinity levels are significant. Sometimes boron, molybdenum, or
magnesium levels are high enough to cause problems. Nitrogen and phosphorus are
nearly always deficient for plant growth.
Power et al. (25) reported up to 50 percent displacement of exchangeable
sodium within 3 years after spoil was treated with gypsum. Doering and Willis (26)
showed that essentially all exchangeable sodium can be removed very quickly with
calcium chloride, but soluble salts formed by reactions must then be leached with
several feet of water before vegetation can be established.
Reclamation in the west hinges on management of available water. Mulches
can be used effectively to conserve moisture. Irrigation should be used whenever
possible to aid plant development at critical times.
As the world's petroleum resources decline, oil shales will increase in
importance as a source of hydrocarbons. Recovering this resource will involve mining
extensive areas. For example, oil shales containing an estimated 600 billion barrels
of oil and considered suitable for commercial development occupy about 17,000
square miles of Colorado, Utah, and Wyoming. Problems of reclaiming spoil material
from overburden removed during strip-mining for oil shales are similar to those
from strip-mining of coal in the western United States.
The major reclamation problem of oil-shale mining involves the spent shale left
after recovery of the oil; this applies to shale mined by underground methods as
well. Coal is used almost in its entirety, but only a small percentage of the volume
of mined shale is recovered as oil. It is estimated that for each 1.5 million tons of
shale mined, 1.3 million tons of spent shale would have to be disposed of.
Depending on the recovery process used, the physical properties of the spent shale
range from clinker-like to dust-like, and each has its own special problems. The
192
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SUITABLE PLANTS
chemical problems are even more serious; they include high levels of salinity, low
organic matter, and low levels of available plant nutrients. The high salinity makes
leaching almost imperative for reclamation, but this is hampered by a shortage of
water in an arid climate. Efforts to utilize topsoiling have been hampered by
capillary rise of salts into the added topsoil.
Considerable research has been done, both in the greenhouse and in the field,
to find plant species suitable for reclaiming oil shale. It has been demonstrated that
only a few salt-tolerant species can be successfully established on unleached spent
shale. Where capillary rise of salts can be stopped by compaction or by interposing
a coarse rubble layer, topsoiling broadens the choice of species. The number of
adaptable species increases with increasing soil depth, up to approximately 1 foot of
topsoil. Little toxicity is associated with spoils from oil shale mining, but because of
the scarcity of water in this region, soluble salts will continue to be a major
obstacle to revegetation.
Perhaps the most significant advance in oil-shale technology is in situ oil
recovery. In this process, the shale is fractured and the oil recovered from it while
the shale is in place. If it proves successful, this method will eliminate the need to
handle and dispose of the billions of tons of waste material and the major
reclamation problems now anticipated will be eliminated.
Vegetation can be successfully established on mine spoil if certain practices are
followed. Some of the more important considerations will be discussed.
SEEDBED PREPARATION
pH FACTORS
LIME
A suitable seedbed was shown by Vogel (27) to be necessary for the rapid and
successful establishment of seeded vegetation on mine spoils. On plots that were
roto-tilled before seeding, vegetative cover was established faster and was denser at
the ends of the first and second growing seasons than it was on plots that were not
tilled. Tillage was more beneficial for seedings made between April 1 and October
15. The main advantage of tillage is that it breaks up the crust on the surface of the
spoils and increases the number of microsites favorable for germination of seed and
growth of the plants. Seeding on freshly graded spoils would provide the same
advantages as tillage at lower cost. Requirements for seedbed preparation are more
stringent in the dry western regions. Specialized implements are needed such as the
rangeland drill for placing seed in furrows, or pitters and gougers that create
depressions to conserve soil moisture.
The amendments to be discussed are lime, fertilizer, and mulch.
The chemical properties that most often influence the establishment and
growth of vegetation on strip-mine spoils are related to chemical reaction and
imbalances in plant nutrients. Acidity or alkalinity is a very useful criterion for
predicting the capacity of spoil to support vegetation. Its intensity is expressed as
pH—a measure of the concentration of hydrogen ions present. Most spoils in the
eastern United States are in the acid range (below pH 7.0), while most spoils in the
western states are alkaline.
Some plant species are more tolerant than others of acid conditions just as
some species are more tolerant than others of alkaline conditions. Nearly all plant
species will grow in spoils with a pH above 5.5 and below 8.0. A more limited
number will grow when pH is between 4.5 and 5.5 or above 8.0. Few species can
tolerate spoil below pH 4.5 and fewer still will grow where pH is below 4.0. In
some of the western areas, species tolerant of alkaline conditions must be selected.
There are problems in establishing vegetation on acid spoils. Toxic levels of
aluminum and manganese are soluble at low pHs and become harmful to plants.
Roots of many plants will not grow into materials with toxic levels of soluble
aluminum. Thus plant growth is stunted because the roots do not take up nutrients.
Some things can be done to ameliorate acid spoils. Amendments such as
organic matter, fly ash, and topsoil may be added, but lime is the most used.
Topsoiling is considered the most economical way of treating alkaline western spoils.
193
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FERTILIZER
MULCHES
CHEMICAL BINDING AGENTS
The most common practice now is to apply enough lime to raise pH to 5.5.
At this pH, manganese and aluminum become less soluble and are less available in
forms toxic to plants. Also, phosphates and other nutrients become more readily
available to plants at the higher pH.
Studies have shown that rock phosphate can be used successfully in reclaiming
spoils when the pH is below 4.5 (28). Rock phosphate contains calcium as well as
phosphorus.
Most surface mine spoils are deficient in one or more essential plant nutrients.
Nitrogen is almost universally lacking; phosphorus is limited in most spoils but is
adequate in some. Potassium levels generally are adequate for the establishment of
vegetation.
A deficiency in nitrogen severely limits establishment and growth of
herbaceous species, especially grass. Thus, the addition of nitrogen fertilizer is
essential.
Further applications of nitrogen fertilizer may be avoided by planting or
seeding nitrogen-fixing plant species. Legumes are used for this purpose, although the
long-lived legumes usually take more than 1 year to get established. This means that
annual legumes or grasses must be used for the initial quick cover needed to control
erosion.
Various mulches can be used during the critical period of seedling
establishment to improve the microclimate and help conserve soil moisture. Among
the many materials that have been tested for use on surface mine spoils are pulp
fiber, grain straw, hay, wood chips, wood bark, leaves, and some chemical binders.
Generally wood pulp fiber is mixed with seed and fertilizer and applied with a
hydroseeder. The amounts of this mulch usually used (900-1100 kg/ha) are
inadequate to reduce erosion significantly. Also, it is doubtful that they have a
significant effect on moisture conservation.
Straw at 2200 to 3400 kg/ha, distributed evenly over the surface after seeding,
can aid in the successful establishment of vegetation on spoils. However, it is often
necessary to hold the straw in place with a binder or to run over it with a disc or
crimper. Hay falls into the same category as straw. Both may retain seed which can
result in a volunteer stand of vegetation. However, seed of some weeds may be
undesirable.
Wood chips are good because they stay in place on the spoil. However, efforts
to establish vegetation with wood chips as a mulch have been disappointing.
Shredded tree bark applied at the rate of about 94 cubic meters per hectare
has been found to be quite effective in conserving moisture, retarding runoff and
erosion, and providing microclimatic conditions favorable to plant establishment and
growth. Leaves, too, have been found to be a valuable mulch. They can be applied
with a blower or with a regular farm manure spreader. Leaves must be disced into
the spoil to hold them in place.
Naturizer is a trade name of a mixture of composted municipal waste and
sewage sludge. Initial tests indicate its use on surface mine sites may be beneficial
both as a way to dispose of waste products and as an aid to mined land
reclamation.*
Many chemical binding agents have been developed over the past few years
and many of them are purported to work well in erosion control. Additional
194
*The use of trade, firm, or corporation names in this publication is for the
information and convenience of the reader. Such use does not constitute an official
endorsement or approval by the U.S. Department of Agriculture or the Forest
Service of any product or service to the exclusion of others that may be suitable.
-------
TOPSOILING
CLIMATE
QUICK COVER
research is necessary to support these claims. When used alone these chemicals
cannot serve all the functions required of a mulch; i.e., they cannot provide
moisture conservation, stabilize the soil, and moderate surface temperature. Neither
do they provide any plant nutrients.
Sewage sludge and effluent have been used successfully in efforts to vegetate
some problem spoils. Much research is underway into the use of these and other
waste materials in reclamation.
Topsoiling is now required on nearly all surface mine disturbance in the
United States. The so-called topsoil is removed from the area about to be mined
and stockpiled for later spreading on the graded site. Almost all the unconsolidated
overburden may be classed as topsoil. In many cases the importance of topsoiling
cannot be disputed, but in some cases another stratum in the overburden may have
more desirable characteristics as a plant growth medium than topsoil. In these cases
the best material for plant growth should be placed on the surface.
For a long time, most seedings of mine spoil in the Appalachian region were
made in the spring or fall, with spring generally being preferred. Many people
believed that even in a humid region it was impossible to vegetate mine spoils by
direct seeding in the summer. Vogel (27) has shown that a vegetative cover can be
established by seeding selected mixtures of temporary and long-lived herbaceous
species anytime between March 1 and October 15 in eastern Kentucky. Results of
his study have been applied with success to other areas in the Appalachian region.
In early spring and fall, initial cover was best achieved with Balbo rye or annual
ryegrass. Pearl millet, sudangrass-sorghum hybrid, and weeping lovegrass provided
quickest cover from mid-May to mid-July. Kentucky-31 fescue and sericea lespedeza
became the primary cover on the areas after two or three growing seasons.
In humid regions, barren areas should be seeded anytime mining is completed
between March 1 and October 15. The seed mix can be changed to fit climatic
conditions throughout this period. Seeding temporary species for quick cover with
the permanent species is desirable in most situations. The temporary species provide
cover sooner than the permanent species, but are later replaced by the permanent
ones.
In any seeding, the species selected often is less important than adherence to
good vegetation practices; i.e., preparation of a suitable seedbed, application of
sufficient fertilizer, and, when necessary, application of lime and mulch.
In the southwest it is important to seed when moisture conditons are best.
For example, fourwing saltbush should be planted only when the probability of
summer thunderstorms exeeds 50 percent and existing soil water stress is less than 2
atmospheres of tension.
The amount and distribution throughout the year of rainfall are strong factors
in the establishment of vegetation. In the east rainfall usually is not a problem, but
in the west and southwest it may be the limiting factor in plant establishment.
Although water is recommended for areas that receive less than 200 mm of
precipitation, it can likely be beneficial for areas receiving much more precipitation.
Species of vegetation for use on surface mine spoils should be selected
according to the time of year, type of spoil, purpose of seeding or planting, and the
expected future use of the land.
One of the first considerations is to establish a quick cover for erosion
control. In the east this generally means a mixture of herbaceous annuals and
perennials. Some woody species may be desirable. When temporary quick-cover
species are mixed with permanent species, there is a chance that the temporary
cover will prevent or retard the development of a satisfactory stand of the
permanent cover. It is important to limit the amount of seed of the annual or
quick-cover species to prevent this.
Many experiments have been conducted to determine the adaptability of
various herbaceous and woody species for vegetating strip-mine spoils. Some species
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PREFERRED PLANT SPECIES
TREES
-have been selected for their tolerance to acid conditions; others have been selected
specifically for use on alkaline spoils. Many species of grasses are well suited to
surface mine reclamation, because they are adapted to a wide range of climatic and
spoil conditions. Some species are desirable because germination is usually rapid and
growth is quite good during the first growing season.
Many plant species have been tried with varying degrees of success in the
United States. For each of the major coal producing regions there are preferred
plant species in each of four major categories: grasses, forbs, shrubs, and trees. The
grasses and forbs may be further classified as temporary, semipermanent, or
permanent Temporary species are used to give quick cover for site protection;
semi-permanent species are reasonably persistent perennials; permanent species are
those expected to persist for many years.
Annual grasses can be used for quick cover and as companion crops with
slower developing perennials. Some species are better adapted to spring seeding,
others should be seeded in the summer, and still others in the fall.
Leguminous forbs are considered essential in ground-cover mixtures. Associated
plants generally benefit from the nitrogen fixed by the legumes. Annual legumes
germinate quickly and provide good cover within a few months. Perennial
leguminous forbs often are more difficult to establish; many have hard seed coats or
other specific dormancy requirements that delay germination. The availability of soil
phosphorus is generally more critical for the establishment of legumes than for
grasses. Seeding rates of companion grass species should be carefully regulated to
prevent excessive competition and possible failure of the legumes. Each species of
legumes must be inoculated with specific strains of Rhizobium to stimulate
nodulation to insure the nitrogen-fixing activity.
Shrubs for reclamation plantings have not been emphasized although they have
significant value for site protection, wildlife food and cover, and esthetics. Possibly
in the future more emphasis will be placed on the use of shrubs.
Trees have generally been a mainstay of reclamation efforts. A few tree species
can be directly seeded but most are normally established by planting seedlings. Many
species are adapted to surface mine spoils, but species native to the area are usually
recommended. Unfortunately, high value tree species are usually the most difficult
to establish on spoils. Grass and legume ground covers generally reduce tree growth,
at least in the early stages. In later years legumes may enhance growth. Black locust,
autumn olive, and bristly locust are nitrogen fixers and can be beneficial as nurse
trees for other tree species.
Revegetation practices in the United States are determined or influenced
mainly by legal requirements for surface mining and reclamation. The seeding of
grasses and herbaceous legumes to establish a cover for erosion control and for
esthetics is generally recommended. Once the herbaceous vegetation is well
established it can be used for pasture and hay. Good forage species usually are used
for vegetating mine spoils-for example, smooth broomgrass and alfalfa in Illinois
and tall fescue and annual lespedeza in southern Appalachia. Livestock grazing is
becoming a commonplace land use on vegetated strip mines even in the mountainous
areas of Appalachia. Unfortunately, the tendency is to overgraze or start grazing
before the vegetation is well established, which hinders the development of adequate
cover.
REFORESTATION
The land use in effect at time of mining often influences the choice of
revegetation practices. For example, prime agricultural land in the flatlands of
Illinois is reclaimed for immediate return to row crop production.
On the other hand, forested land is usually not replanted to forest species.
Some states require that woody species be planted in addition to the herbaceous
species on steep slopes and other sites not intended for agricultural use. Normally
the planting of woody species is optional for the landowner or mining company.
The legal requirements in some states unintentionally discourage tree planting
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BLACK LOCUST
QUICK COVER VS. TREES
LEGAL REQUIREMENTS
because they permit release of vegetation bonds as soon as the requirements for the
herbaceous vegetative cover are met.
Black locust is still the most commonly used tree species. It is especially
popular for use on steep slopes because it can be established by direct seeding in
mixture with herbaceous species. Locust seedlings respond to fertilizer, especially
phosphorus, as herbaceous legumes do, and first-year seedling heights of 30 cm or
more are not uncommon. Unpopular doghair stands of locust sometimes develop
where seeding rates are excessive. European black alder and autumn olive are other
nitrogen-fixing woody plants that are used as nurse plants or site improvers and for
wildlife habitat.
Red pine, white pine, and hybrid poplar have been successful in the northern
Appalachian coal fields. European white birch has been the most successful tree
species on extremely acid spoils in Pennsylvania. Virginia pine has been widely
planted in the middle and southern Appalachian region, and loblolly pine is often
planted or direct-seeded in southern Appalachia. Most species of pine are tolerant of
acid spoils, especially in association with the acid-tolerant mycorrhizal associate,
Pisolithus tinctorius (20).
Tree planting now is rare in the midwest even though reforestation studies
showed that high value hardwoods can be produced on spoils. This is due in part to
political and social pressures that favor agricultural uses of all surface-mined lands.
Also, hand planting of tree seedlings costs more and entails more labor-related
problems than seeding of herbaceous species. Another reason for choosing
agricultural uses over forestry is the greater and quicker economic return from the
reclaimed land. Yet, some of the 30- to 50-year-old hardwood stands, especially of
black walnut, in Indiana and Illinois demonstrate the economic potential of growing
forests on mined lands.
There is a need to establish a quick cover for erosion control at the same time
that trees are planted, but the herbaceous vegetation may adversely affect survival
and growth of the planted trees. Some people recommend seeding the herbaceous
species one year and planting trees the next. Others suggest using herbicides to kill
patches of herbaceous vegetation where tree seedlings will be planted. A more
practical method is to plant trees and herbaceous species at the same time. The
herbaceous cover should consist mainly of legumes because the growth of trees
usually is enhanced by legumes but suppressed by grass (29). When seeding must be
done in late spring and summer, an herbaceous cover can be established with
summer annuals. These will die in the fall and provide a mulch over winter. Trees
and perennial herbaceous species can be planted the following spring.
On areas that can be traversed with farm machinery, early competition of
herbaceous species with trees can be avoided by planting the herbaceous species and
trees in alternate strips. To further assure their establishment and early growth, tree
seedlings should be inoculated with the appropriate mycorrhizal fungi.
Revegetated surface mines can provide excellent wildlife habitat and
water-based recreation, as is shown on many old strip mine sites. Present
revegetation practices in the east often provide poor wildlife habitat because they
use mainly a few species of grasses and legumes such as tall fescue and sericea
lespedeza that provide little food or diversity of habitat.
Perhaps the most significant piece of legislation relating to surface mining and
reclamation was the Surface Mining Control and Reclamation Act of 1977 and
subsequent interim regulations pertaining to that law. Since the act was passed in
August 1977, many states have enacted legislation that conforms to the federal
requirements.
Some of the specific legal requirements for reclaiming surface-mined land will
be discussed.
Reclamation options often depend on how the overburden is handled and
placed during the mining operation. Controlled placement of spoil should result in
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NUTRIENTS/AMENDMENTS
SITE PREPARATION
improved slope stability and should provide the best possible conditions for
vegetation establishment and growth.
The importance of overburden analyses must be emphasized since overburden
characteristics play a large part in determining the future land use. Knowledge of
the chemical and physical characteristics of the overburden can be helpful in
designing spoil movement and placement systems for minimizing environmental
damages and maximizing future land use options.
Topsoiling is required unless alternate methods are approved. Topsoiling refers
to the practice of removing the A, B, and C horizons individually or in
combinations before mining, then redistributing these materials on the mined area to
prepare the site for vegetation establishment. Where prime farmland is mined,
requirements relating to topsoil removal, storage, and replacement are more stringent.
Topsoiling is a questionable practice on steep slopes in many areas in
Appalachia where the soils are shallow and infertile. An alternative is to use selected
portions of the overburden materials. According to regulations the decision to
substitute overburden materials for topsoil must be supported by chemical and
physical analyses and field or greenhouse trials. The intent of the regulations relating
to topsoiling is to provide the best medium for plant establishment and growth.
Nutrients and amendments must be applied as indicated by soil tests and
vegetation requirements. However, not all standard soil tests are applicable to surface
mine spoils. Greenhouse and field tests usually are required to verify the accuracy of
soil tests. Fifty pounds of nitrogen and 40 pounds of phosphorus per acre are
considered minimum on most spoils for establishment of herbaceous vegetation.
Lime can be used to neutralize acidity. Lime should be incorporated at least 6
inches deep to be most effective. Rock phosphate also is an effective amendment in
some acid spoils.
Regulations require prompt vegetative cover capable of stabilizing the soil
surface with respect to erosion and productivity levels compatible with approved
land uses. Grasses are usually more reliable for early site protection. Legumes are
important in reclamation because of their nitrogen-fixing ability. Mixtures of grasses
and legumes in the proper proportions are often used for reclamation.
A number of state laws require trees or other woody plants on steep slopes or
areas having a high potential for erosion. Tree planting or seeding will continue since
wood production will continue to be the land use for many areas after mining.
Regulations require that where forest is to be the future use, trees adapted to local
site conditions and climate be selected. Trees are to be planted in combination with
an herbaceous cover of grains, grasses, legumes, forbs, or woody plants to provide
variety, succession, and regeneration capability in the area.
Requirements are that any disturbed areas which have been graded be seeded
with grains, grasses, or legumes for temporary cover to control erosion until the
permanent cover is established. This requirement forces operators to plant or seed
the freshly graded spoil and thus benefit from the fresh seedbed. It may be
necessary to do further seedbed preparation to enhance the establishment of the
permanent cover.
Mulches must be used on all regraded and topsoiled areas. Straw and hay are
the most widely used mulching materials, and they are among the most effective.
Shredded hardwood bark is also an effective mulch. Processed wood fiber and
reprocessed paper products are used rather extensively as mulch in Appalachia
because they can be applied with seed and fertilizer from a hydroseeder.
Federal law requires that all disturbed areas be restored in a timely manner to
conditions capable of supporting the uses they were capable of supporting before
any mining, or to higher or better uses as specified and approved.
The short-term success of reclamation is definitely determined by criteria set
up by regulatory authorities. Usually the standards require a minimum ground cover
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TOPSOILING
LAND USE OPTIONS
WASTE AS SOIL
AMENDMENTS
density within a specific time period. The number of woody seedlings per acre may
be stipulated for steep slopes. Supplemental seeding, fertilizing, liming, mulching, and
planting may be required to achieve the minimum performance standards. Once
reclamation meets all legal requirements, the performance bond is released, and the
land manager may then do whatever is required to achieve the desired land use
objectives.
We must be careful that, through legislation and regulation, we do not
foreclose land use options for surface mined land. Laws and regulations should be
flexible enough that the land owner or land manager has some input as to the
proposed future use of the land.
Although topsoiling may be an attractive reclamation practice on some sites,
its full potential cannot be realized without additional research. What are the effects
of storage on physical, chemical, and biological properties of topsoil? Would topsoil
be more effective if blended with selected overburden materials? Could
microbiological activity be improved through blending? What about chemical and
physical properties? What is the optimum depth of topsoil over coarse textured but
non-toxic spoil, and over extremely acid material?
Chemical binders used with or without wood fiber have received some interest
recently as soil stabilizers. The potential of these materials for binding soil particles
and retarding erosion has not been demonstrated.
There is little documented information regarding the productivity of surface
mined lands. It is believed that under proper management many sites could be very
productive. We need to start research into the management of reclaimed land so that
we can document site productivity.
In many cases there may be more than one use that can be made of land
mined and reclaimed. There is need for work aimed at defining various land use
options available to the land owner or mine operator. Reclamation activities should
be designed to provide maximum land productivity over the longest term.
Although it may be desirable from the ground cover standpoint to plant trees
together with an herbaceous cover, it is not always practical to do so. For example,
we don't yet know what combinations of species are compatible. Some specific
questions to be answered are: Do trees perform better in association with grasses,
legumes, or mixtures of these? Should trees and herbaceous cover be established at
the same time or should tree planting be delayed a few years? Should only native
species of trees be used? Older hardwood plantings have been found to be fairly
successful, yet we are having trouble getting hardwood plantations established now.
Why?
To meet specific land use goals some effort should be aimed at selecting and
testing superior plants for mined land reclamation. This means selecting not only the
best species but, perhaps more important, genotypes within species.
Studies should be made to determine the best combinations and patterns of
vegetation as well as the best surface configurations on mined land to benefit
wildlife. Research must also be done to find the best ways to mine and reclaim land
with the least adverse impacts on visual resources.
Reviews of past work show that despite the availability of much information
on how to establish vegetation, there are many areas where technology is lacking.
Additional studies on plant establishment are needed for refining current practices
and restoring biological productivity through a better understanding of soil-plant-
animal relationships.
Some studies already show benefits that may arise from using various waste
materials as soil amendments. More research is needed in this area so that we may
be better able to dispose of waste materials in such a way as to enhance land
productivity.
Federal law requires that surface mining and reclamation be conducted so as
to maintain the present hydrologic balance. Research is needed in all phases of the
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EROSION
FOREST SERVICE
PERFORMANCE EVALUATION
water cycle in relation to surface mining and reclamation activities to safeguard our
water resources.
General observations tend to support the belief that replaced topsoil erodes
faster than does spoil material on similar sites. A serious consequence of this erosion
is the permanent loss of the topsoil as a medium for plant growth on strip-mined
areas. Another consequence is stream siltation. Ways must be developed to control
erosion on surface mined lands.
The federal regulations extend the time of responsibility of a mine operator
for successful revegetation. With what types of vegetative cover and under what
management practices can an operator be sure of complying with this requirement?
The vegetation bond represents capital not really producing anything.
It is very important to avoid introduction of toxic or harmful elements and
compounds into the food chain. Toward this end there is need to carefully evaluate
the quality of forage, feed, and food crops produced on surface-mined lands,
especially where waste materials are used in the reclamation process.
Spoil instability is still a major problem. This includes not only surface erosion
but subsidence, piping, sliding, and slumping. Proper water control both on the
surface and within the spoil mass is not to be ignored. Mining methods, earth
moving operations, and overburden placement schemes must be evaluated as they
relate to stability. Techniques must be developed for selecting the mining and spoil
handling systems most appropriate to each situation.
Information contained in this part of this paper was taken from materials
supplied by the various agencies and departments. The material was abstracted and
rearranged in the format required of the paper. In some cases not all the material
furnished was used. Some of the research reported here was conducted cooperatively
with the EPA and supported in part by interagency environmental agreements.
The Forest Service has been involved in mined land reclamation research in the
eastern United States for over 30 years. Its program was expanded in the early
1960"s with a mission to develop practical methods of reducing damage to the
environment and forest resources during surface mining operations and to rehabilitate
mined areas for the production of quality water, timber, wildlife, recreation, range,
and esthetic benefits. Other reclamation research is being handled in the west under
the SEAM program.
In 1946 and 1947 the Central States Forest Experiment Station began
experiments basic to the formulation of planting guides and recommendations for
reforesting surface mine sites. Many plots were established throughout the
surface-mining areas in Ohio, Indiana, Illinois, and western Kentucky as well as in
eastern Missouri, Kansas, and Oklahoma.
The Northeastern Forest Experiment Station initiated studies in cooperation
with Southern Illinois University and the Ohio Agricultural Research and
Development Center in 1976 to evaluate the performance of these plantations. Of
the 23 species observed, outstanding growth was noted in black walnut, cottonwood,
chestnut oak, red oak, sweetgum, and yellow-poplar.
Height of hardwoods at several locations was greater than 70 feet (21.3 m).
Several individual cottonwoods, red oaks, and yellow-poplars were taller than 90 feet
(27.4 m). Black walnut, yellow-poplar, red oak, and silver maple performed better in
plots where black locust was used as a nurse tree than where locust was not
planted. Over 60 different species of volunteer trees were observed. Many woody
vines as well as herbaceous and shrubby plant species were common.
Tree growth was suppressed where trees were planted with a grass cover, but it
was enhanced by lespedeza, a legume. This indicates that trees and a herbaceous
cover comprised mostly of legumes can be established together without adversely
affecting the trees.
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TEST PLOTS
WATER QUALITY DATA
NONMINE WASTE USE
Large scale test plots using equipment and methods which are operationally
practical were established by the Rocky Mountain Forest and Range Experiment
Station in the summer of 1977 on the McKinley Coal Mine in northwestern New
Mexico. Treatments included incorporating straw at 8 metric tons per hectare,
contour furrowing with and without straw, and checks. Initial observation in
October of 1977 showed good germination of the seeded wheat-grasses on all areas.
An unusually wet period shortly after seeding in August produced good germination
even in unmulched areas. Chemical and physical spoil properties were more favorable
than normal in this area because of the age and source of the exposed materials.
At present, the most promising species to plant on mine spoils in the
southwest are alkali sacaton, western wheatgrass, fourwing saltbush, and Indian
ricegrass. Good stands of alkali sacaton have resulted when pure live seed was
applied at a rate of 3 kg/ha. Drilling is by far the most common method of
planting seeds on reclaimed areas in the southwest. The rangeland drill has worked
best. Fourwing saltbush seedlings should be planted in areas that will be flooded
periodically. It is best to wait until the probability for sizable (10 mm plus) summer
thunderstorms exceeds 50 percent, and soil water stress is less than 2 atmospheres
of tension. Transplant plugs of western wheatgrass were field planted successfully.
Investigations in New Mexico have shown advantages of using mulch to establish
perennial species. Straw spread at a rate of 2,240 kg/ha and rototilled into the top
8 cm of spoil was effective in the establishment of fourwing saltbush transplants and
seeded alkali sacaton on mine spoils. Some type of supplemental water is
recommended for areas receiving less than 200 mm of precipitation. When an
overhead sprinkler system was used to apply 254 mm of water in the first growing
season, an average of 86 alkali sacaton seedlings per m^ became established.
There is a need for water quality data from small Appalachian watersheds that
will explicitly show changes in water quality attributable to strip mining. Most
existing data are from large watersheds in which it is impossible to isolate the effects
of strip mining from the effects of deep mining, settlement, and farming.
Work is under way to establish water quality data bases for small first-order
watersheds throughout Appalachia, on unmined watersheds, newly strip-mined
watersheds, and old strip-mined watersheds. The data base, once established, can be
used as a basis for evaluating both short-term and long-term effects on streams of
different kinds of strip mining and reclamation. It can also serve as a frame of
reference for future studies on these and nearby watersheds.
Sampling sites have been established for each of these three watershed
conditions in 135 Appalachian counties where there is an appreciable amount of
surface mining. These counties reach from northern Pennsylvania to central Alabama.
Monthly samples are collected and analyzed for common ions, specific conductance,
pH, and for 12 to 28 trace elements.
Preliminary analysis indicates a wide scatter in the chemical data. Water from
some streams draining recent and old strip mines was scarcely distinguishable from
that from nearby unmined watersheds, and in three streams it was actually a little
better. A comparison of 58 pairs of old and new mined watersheds showed that in
37 instances the drainage from the newly mined area was better than that from the
old mined area. Twenty-one of the old mined watersheds had better quality water
than the newly mined areas.
Data from Bear Branch watersheds showed that for a major storm on April
3-4, 1977, flow from well reclaimed surface mined watersheds peaked lower than
that from an unmined, forested watershed.
Plots have been established in northeastern Alabama, western and eastern
Kentucky, and West Virginia to study the use of nonmine wastes as amendments in
reclaiming surface mine spoils. Many of these plots have been instrumented with
recording water runoff gages, erosion transects, suction lysimeters, and samplers for
collecting surface runoff at different stages of flow. The surface and ground water
samples are analyzed for the common dissolved constituents plus 12 trace elements.
Soil samples collected periodically are analyzed for various dissolved, extractable, and
201
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MULCH USE
PLANTING METHODS
SHEAR TESTS
exchangeable constituents. The vegetation on each plot is periodically photographed
and evaluated.
Findings to date indicate that in general the response to a given mulch is
highly dependent upon season of year, aspect, slope, and type of the mulch. Bark,
hay, straw, wood chips, and hydromulch, in that order, all effectively promoted the
growth of legumes in Alabama and western Kentucky. From 66 percent to 89
percent plant cover was established under bark and hay at two sites as contrasted to
22 percent and 34 percent cover on the controls. Straw was the best mulch at a
third site, but was least effective at one of the other sites.
Shredded hardwood bark, limestone chips, hydromulch, composted garbage,
and a paper-nylon blanket were used on an outslope plot near Elkins, West Virginia.
After one growing season, the bark and composted garbage ranked highest for
legume growth and plant distribution; hydromulch resulted in the poorest legume
growth. Grass density and growth were better where limestone chips, composted
garbage, and paper-nylon blanket were used. Best erosion control was achieved with
the paper-nylon blanket; bark ranked a close second.
Studies installed in 1977 have confirmed data from previous studies that
indicate that mulching increases survival of planted hardwood seedlings. Individual
seedlings were mulched with one bushel of shredded hardwood bark. This provided a
depth of about 10 cm for a radius of 38 cm from the stem. Survival of the
mulched trees was 36 percent higher than that of the unmulched trees. Survival of
yellow-poplar and cottonwood was not enchanced by mulching.
Data from old and new studies indicate that planting methods may present
problems. In 1978 a study was installed to compare trees planted using a planting
bar, mattock, power-auger hole backfilled'with spoil, and power-auger hole backfilled
with top soil. Shredded hardwood bark mulch also is being evaluated. To minimize
human error, highly experienced personnel were used. Every phase was under control
from lifting the trees in the nursery through the final planting. Since all conditions
were optimal, differences in survival and subsequent growth should be due to the
method of planting or to the mulch.
Data collected on the effectiveness of topsoiling as a reclamation technique
indicate that herbaceous plant root structures are well branched and fully occupy
the available growth space of the topsoil. However, with subsequent growth into the
spoil material the root structure changes into single strands with little or no
branching.
Blackberry seeds showed different responses to seven different minespoils under
greenhouse conditions. The largest of three Kentucky seed size-classes germinated
best and survived best on all minespoils tested. Although yields showed no
consistent correlation with the chemical or physical factors for the minespoils, pH,
potassium, organic carbon, and silt fractions gave the highest r-values.
Experimental vegetation plots have been established on coal spoils in Montana,
Wyoming, and Utah. A study was installed to determine appropriate rates and
frequency of fertilizer application for establishing various species of grasses, forbs,
and shrubs. Direct seeding is being compared with planting containerized seedlings.
The effects of four different types of spoil on plant growth are being tested in the
field. Various treatments of topsoil, bark-wood fiber compost, and hay mulch have
been applied on plots in the Alton, Utah, coal field. Superior shrubs and grasses are
being developed to provide plant materials more suitable for hostile spoils in the
semiarid west.
Direct shear tests give acceptable estimates of the shear strength parameters of
surface mine spoils. If plans for mining operations are based upon results of such
tests, reclaimed areas in the future should be more stable than those reclaimed in
the past.
At least 14 species of small mammals were found on reclaimed surface mines
in Kentucky. The species composition and densities were related to the reclamation
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SPENT OIL SHALES
plants initially used, and to the current successional stages of plants on the
minespoil and surrounding plant communities. Three species of mice were shown to
be active vectors of the endomycorrhizal fungi on recently reclaimed minespoils.
Spent oil shales present a more difficult challenge for revegetation than coal
mine spoils. A greenhouse bioassay study was completed using five nonmine waste
amendments on leached and unleached TOSCO spent shale. Sewage sludge had more
beneficial effects on plant growth than did fiber, straw, sugar beet pulp, or cow
manure. Sewage sludge apparently ties up the sodium salts in spent shale. Field plots
were established in the oil shale areas of Colorado and Utah. Different depths of
topsoil were applied to spent shale, and test species of grasses and shrubs were
grown under irrigated and nonirrigated conditions. There was little difference in
growth on the topsoil-treated shale, but irrigation was beneficial on raw shale. Soil
covering of 1 foot or more gave better plant growth than did shallower soil
coverings. Other studies are designed to compare fall seedings with spring*planted
containerized stock and to assess the significance of snow accumulation behind
standard snow fencing. One study showed that plants grew better on shale covered
with topsoil or subsoil than when mulched with rock or straw without topsoil.
SOIL FORMATION
SLUDGE AMENDMENTS
The Department of Agriculture conducts a grant program in energy-related
reclamation and environmental effects research through its network of universities
and State Agricultural Experiment Stations. Grants are solicited under specific
guidelines for work on high-priority research topics. Following are some results from
the first group of reclamation grants funded by Cooperative Research.
On the Black Mesa mine in Arizona a study by the University of Arizona
showed coal mine spoil to be highly productive under irrigation. The project is also
using soil pitting to enhance rainfall use.
Studies conducted by Montana State University in the Colstrip area show that
soil formation can be easily detected in 50-year-old sites. The key properties of the
profile are carbonate movement, clay movement, organic matter build-up and root
development.
In another study in Montana, field tests of mixtures of grasses show that
planting a low number of species components is preferable to highly complex seed
mixtures. Good density was achieved when slender, western, and thickspike
wheatgrass were used in equal proportions of 645 live seed per square meter. A
second promising mixture for minespoils is green needlegrass, fourwing saltbush,
prairie sandreed, and switchgrass. Introduced species germinated best. Prechilling
significantly improved speed of elongation of the seedlings in all species. Millet and
slender white prairie clover are promising for some uses.
New Mexico State University tested field plantings of Indian ricegrass and
fourwing saltbush on the Navajo mine and the San Juan mine. The plantings were
not adversely affected by NaCI or Na2SO4 salts; in fact, they were enhanced at 50
to 100 meq of Na per liter of soil saturation extract. Indian ricegrass was also
tolerant of boron salt in the growth medium. Galleta grass is sensitive to boron. An
extensive collection of shrubs and grasses is still under test. At least 13 species look
promising for use in reclamation.
Sewage sludges used as soil amendments were found by Ohio State University
researchers to vary significantly in toxic heavy metal content. Newark sludge was a
valuable amendment. Bellaire sludge was somewhat toxic due to N, Mn, and Zn. Tall
fescue grew well with moderate loading rates of both sludges. The leachate from
treated lysimeters showed that Bellaire sludge leaches out Mn, Al, Ni, and Cd. The
cadmium content in leachates varied from 6 to 94 micrograms/liter which might be
a deterrent to its use as a soil amendment. Topsoiling was effective on two sites.
Grass predominated on acidic sandstone soils and legumes on limestone soils.
Utah State University scientists showed success with container-grown desert
shrubs in large pots. Field planting of shrubs was generally better in spring than in
fall for fourwing saltbush, shadscale, and cuneate saltbush. Fourwing saltbush is one
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HYDROLOGIC MODEL
ORNAMENTAL PLANTS
REACTIONS TO SALT
of the best reclamation species. To stabilize soil and promote runoff and water
harvesting, two commercial products, Soil Seal and Aerospray 10 proved to be
effective for more than 1 year. Polyvinyl acetate (product 3011) applied to shallow
basins increased water retention and also promoted runoff when sprayed on slopes.
A computerized hydrologic model for predicting infiltration, soil erosion, and
water quality has been modified by Iowa State University for use in mine
management. Drainage systems for minelands have been designed on the basis of
hydraulic conductivity data. A study of piezometer water levels in the disturbed
substratum is being used to chart groundwater changes in reclaimed areas.
The University of Kentucky has characterized the geologic conditions at four
shale and sandstone sites and evaluated the potential of spoil materials as
growth-support media for grasses and legumes. They report that the phosphorus
status of the soil and its potential acidity are key parameters. Water holding
capacity and infiltration are also factors related to the geology of the site which
determine what plant species can be employed. One of the best for difficult sites is
tall fescue.
At North Dakota State University, these computer models are operational: 1)
Agricultural Sector Simulation Model, 2) River Model, 3) Environmental Quality
Model, 4) Economic Model, 5) Coal Development Model, 6) Demographic Model, 7)
Government Model. A new model simulating coal mining, conversion and land
reclamation is being developed with links to the above models. The system, RIM AS,
will provide information and maps to determine baseline conditions and to predict
impacts of energy development.
Research underway at the University of Virginia showed that woody
ornamental plants can be grown commercially on minesoils. Vegetables also produce
high-quality yields when grown with sawdust and with black plastic. Water
deficiency of coarse spoil is controllable by mulches.
A project conducted by West Virginia University classifies minesoils on the
basis of their internal characteristics. All are called Spolents. In the next lower
category Great Groups are set apart on the basis of soil temperature and moisture
regimes. Subgroups are distinguished by their lithology. Families are defined by
particle size, mineralogy, soil reaction, and soil temperature. Topsoils have also been
classified.
Atmospheric pollution from burning coal is caused by S02 gas which produces
sulphurous acid upon contact with moisture. At the University of Wyoming, sensitive
indicator plants have been found and the response of the native flora and crop
plants has been measured under controlled atmospheric conditions. Two promising
indicators are bracken fern and ponderosa pine.
Science and Education Administration—FR, formerly the Agricultural Research
Service (ARS), is involved in research aimed at restoring and enhancing agricultural
productivity. Much surface mined land will be returned to some form of agricultural
use. The following information was extracted from the annual report on soil, water,
and air science research (of SEA-FR) compiled for 1977.t
Research at Mandan, North Dakota, is concerned with the stage of plant
development in relation to how species respond to salt. Response of eight perennial
forage species to Na and Mg as well as to total salt concentration in two mine
spoils was evaluated. Evaluations were made at three stages of plant development:
germination, emergence-establishment, and growth. Results show that species respond
differently to similar salt levels and ion concentrations. Stage of plant development
was also important in how species responded. Greatest effects were apparent during
tThe research workers in the soil, water, and air sciences of SEA-FR publish
the results of their investigations in the open literature as quickly as sound scientific
judgment warrants. The above-mentioned annual report provides a brief overview of
the scope of their activities and examples of recent findings, some of which have
not been released for publication.
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SAMPLE COLLECTION
CONSEQUENCES
the period of emergence and stand establishment. If the character of the soil-spoil
complex is known before mining, seeding mixtures can be selected, the specific
response of certain species can be better managed, and adverse reactions can be
limited.
Studies are being conducted on the effects that overburden sample collection
methods have on the results of chemical analyses. Water with high salt content and
drilling mud used as a drilling fluid in sampling overburden may result in
contamination of the sample. Sodium absorption ratio (SAR) is the preferred
method for characterizing the sodium status.
Five cm of topsoil added to sodic spoils and seeded to native grasses in 1970
produced over 1200 kg dry matter/ha in 1976, compared with about 200 kg/ha for
spoil without topsoil. A good sod of western wheatgrass and green needlegrass
developed even though sodium had migrated into the applied topsoil, raising its SAR
from about 1 to over 8. Similar sodium migration was seen in other experiments
where greater thicknesses of soil materials had been added. Data indicated that
upward sodium migration will probably occur for 15 to 30 cm above the soil-spoil
interface. Upward sodium migration can be reduced or eliminated by applying
gypsum to spoils before covering them with soil material. Likewise, gypsum
treatment can reduce SAR in the first 30 cm of spoil by 30 to 50 percent over a
period of 3 to 4 years. A minimum of about 75 cm of soil material needs to be
returned to sodic spoils to restore full production potential-at least for spring
wheat, alfalfa, crested wheatgrass, and several native grasses. If upward salt
migration, restricted internal drainage, erosion, compaction, etc., are of significance,
this minimum requirement needs to be increased. However, less thickness is required
if higher quality spoils are present. Even with highly sodic spoils covered with soil,
plant roots penetrate 30 cm or more into the spoil and utilize any water stored
there. Reclaimed spoils usually require fertilization with N and P.
SPOIL CHARACTERIZATION
SPOIL TEST SITE
Other research at Mandan involves characterization of spoils. Overburden
samples have been collected and analyzed from a number of coal fields in western
North Dakota, and more intensive sampling has been done in the Underwood coal
field. At several mine sites, spoils have also been sampled to the depth of mining.
Spoil properties vary widely from site to site, and it appears that characterization
will need to be site-specific within each permit area. Variation with depth in
smoothed spoils is relatively low. Electrical conductivity of smoothed spoils after
mining is often higher than that of unmined overburden. A series of experimental
plots was established at four mine sites in which succession of native grass species is
being studied, both with and without topsoil over the spoils. Vegetation the first
year consisted primarily of annual weeds. In the fall of 1974, perennial grass seed
was introduced by mulching plots with native prairie hay. This resulted in the
initiation of a large number of perennial native grasses and forbs. To date prairie
junegrass predominates on all plots. This technique seems to have potential for
hastening natural succession.
At University Park, Pennsylvania, 6 m depth of strip mine spoil has been
excavated, transported to Klingerstown, and reconstructed in two, 2 m diameter x 4
m caissons. The caissons have been instrumented with lysimeters, tensiometers, water
and temperature access tubes, a groundwater well, and 02 diffusion chambers.
Conductivity, pH, acidity, Ca, Mg, and 50^ analyses have been carried out at each
foot of depth in the spoil. Concurrently, physical properties such as hydraulic
conductivity and particle size distribution were measured. Soils surrounding the spoil
area and mine soils in the spoil area have been described, classified, and analyzed in
detail. The Ohio State University model of acid production from a drift mine has
been adapted to describe acid production in caissons of strip mine spoil. At 10
randomly chosen sites on the experimental area, values of hydraulic conductivity,
bulk density, porosity, and field capacity have been determined on the top 20-30
cm of the profile. Results show the Lower Kittanning spoil to have a lower bulk
density, but higher conductivity, porosity, and field capacity than surrounding soils.
Preliminary comparison of microlysimeter data with standard pan data suggests that
evapotranspiration on strip mine spoil may be approximated with standard pans.
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CLIMATOLOGICAL TESTS
Water measuring flumes, sediment samplers, rain and snow gages, and other
climatological instruments have been installed on a mined and an unmined watershed
near Steamboat Springs in northwestern Colorado. Stage recorders and sediment
samplers have also been installed at three sites on Fish Creek, which drains the
overall mined area. This instrumentation will allow evaluation of the effects of
surface mining on water quality and quantity.
Water samples from the watershed sites and Fish Creek sites have been
analyzed for EC, pH, HCC^, Cl, N03, S04, Ca, Mg, K, and Na for the period May
5 to October 4, 1976. Using EC as an indicator of overall quality, the analysis
indicated a recurring pattern of increased EC in one mined area, but revealed strong
effects from local inflows, suggesting natural spatial variation in water quality. A
numerical, physically-based model, capable of simulating water and sediment
movement rates on a watershed during a storm, has been shown to simulate data
from a natural rangeland watershed accurately.
GREENHOUSE STUDIES
SITE APPLICATIONS
Greenhouse studies at Beltsville, Maryland, have shown a slight improvement in
legume yields on acid mine spoils when the commercial inoculant "Implant" was
used instead of conventional inoculation. Another greenhouse test showed that while
175 MT/ha sludge compost gave the highest forage yields, the spoil pH was raised to
only pH 3.5. Additions of 35 MT/ha of fluidized bed material (FBM, a by-product
of a new coal burning process) with 175 MT/ha compost gave a similar yield, but
raised the spoil pH to about 6.5. The neutralizing value of FBM can be increased by
pulverizing it to 100-mesh size. The neutralizing value of FBM in a pH 2.6 strip
mine spoil is approximately one-half that of
Subsoil applications of lime and rock phosphate to strip-mine spoils by means
of a special subsoiling machine promoted root growth of tall fescue to a depth of
55 cm. Surface applications of lime and rock phosphate permitted root penetration
to a depth of only 35 cm. The deep-placement technique has been used for subsoil
placement of composted sewage sludge in studies of the effects of vertical mulch.
Analysis for 14 elements of plants growing on reclaimed mine spoils in the
east shows that they would meet the nutritional requirements of animals. Se
concentration was above 0.1 ppm while control plants had less than 0.1 ppm. Fly
ash is a source of Se available to plants. It is also a source of Mo which could
reach toxic levels if Cu concentrations remain low. In the west, grasses from mine
spoils were generally low in Cu, Zn, K, Ca, and Mg. Sagebrush contained more than
4 ppm Se, which could be slightly toxic. Fluoride concentrations have ranged from
less than 1 ppm to 100 ppm.
At Blacksburg, Virginia, studies using special crops show a need for mulch as
well as fertilizer. Two-year mean yields with specialty crops of tomatoes and
October beans indicated the need for mulch and adequate amounts of nitrogen. The
highest tomato yields (30 MT/ha) were obtained from Big Boy and Supersonic
varieties with high nitrogen (336 kg/ha) and sawdust mulch. Overall average yields
from sawdust were 20.8 MT/ha, from straw 17.6, and from no mulch 12.3. The
highest shelled October bean yield of 4.3 MT/ha was obtained from the high
fertility level and sawdust mulch. Yield increases of 50 percent to 70 percent
resulted from the use of sawdust as a mulch. Concentrations of elements in leaf
tissue and edible fruit were for the most part within the normal range established
for these vegetables.
SEEDING GROUND COVER
Seedling growth in rough surface conditions offers quicker ground cover and
minimizes erosion. Forage harvested from hydroseeding on a rough surface averaged
yields of 4025 kg/ha compared with 3930 from the agricultural seeder. Nurse crops
caused a wide range in density of grasses, legumes, and bare ground as follows:
hairy vetch 55 percent, 39 percent, and 6 percent; rye 40 percent, 23 percent, and
36 percent, respectively. From a fertility and species-persistence study, yields in the
sixth harvest year were: bromegrass 5540 kg/ha, orchardgrass 3800, Ky 31 fescue
3475, and timothy 5150. Forage yields from rock phosphate averaged 4450 kg/ha,
and from lime plus superphosphate 3760 kg/ha.
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CULTIVAR YIELDS
MICROBIOLOGICAL RESULTS
VEGETATION CONCENTRATION
MECHANISM
Rock phosphate continues to be one of the better amendments on distrubed
soil materials having a pH below 5.0. Third year plant density counts indicated the
persistence of special-purpose legumes. Treatments seeded with sericea averaged 65
percent and with crownvetch 75 percent; Kobe lespedeza and red clover dropped to
15 percent. Of interest was the high density of ladino clover, averaging 79 percent.
Yields (dry weight basis) favored species mixtures of sericea lespedeza and Ky 31
fescue, and sericea and weeping lovegrass, which averaged 6270 kg/ha.
Yields of five buckwheat cultivars grown on low-pH strip mine spoils in
Morgantown, West Virginia, and on low-fertility marginal land soils averaged 1345
kg/ha from marginal lands or approximately 5 times the average grain production on
reclaimed strip mines. Nitrogen and P increments did not stimulate yield on marginal
soils, but nitrogen application promoted a small yield increase on strip mine soils.
Buckwheat samples from field locations did not contain hazardous levels of Pb, Cd,
Cr, Ni, Cu, or Co. However, greenhouse buckwheat forage from mine spoils amended
with fly ash contained increased concentrations of several essential elements but
phytotoxic levels of B. Plant concentrations of Cu, Ni, and Cd exceeded normal
amounts. Tufcote and Midland bermudagrasses have been successfully maintained on
low pH strip mine spoil over a 5-year period using complete fertilizer and lime or
raw rock phosphate as soil amendments. After 5 years, highest yields were obtained
at the highest lime rate (8 MT/ha) or with 4 MT/ha of raw rock phosphate.
Bermudagrass forage quality was sufficient for grazing beef cattle but not for
producing dairy cows. Aluminum and Mn content of bermudagrass forage was
decreased by applications of lime, whereas P levels were significantly increased by
applications of raw rock phosphate. The magnesium levels in forage from mine spoils
were extremely low (0.05 to 0.10). Spoil pH was increased from 3.5 to a high of
6.5 with 8 MT/ha of lime. Raw rock phosphate (2 MT/ha) increased the pH to
approximately 5.
Also near Morgantown, erosion of steep outer slope areas on low pH strip
mine spoils was successfully controlled by use of several species including tufcote
bermudagrass, tall fescue, and redtop. Lime or cornbinations of lime and raw rock
phosphate were essential for good establishment and growth of all species.
Microbiological examination of disturbed and undisturbed soils on strip mine
sites indicated that numerous heterotrophic soil microorganisms resided in the
rhizosphere of plants on mine spoil treated with lime or sewage sludge, but no
longer existed in unvegetated spoils. Nearly 150 isolates of bacteria, actinomycetes,
and fungi have been collected from vegetated strip mine areas and are currently
being identified. Analytical procedures for elemental analysis of plant material, soil,
and water using an induction coupled plasma quantometer (ICPQ) .have shown that
its detection limits for AL, B, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, P, Pb, Sr,
and Zn are as good as, and in most cases better than those of atomic absorption.
Detection limits of Na, Se, and K were somewhat poorer than with atomic
absorption. Methods for sulfur determination in plants and mine spoil material have
been developed using a Leco IR 33 sulfur analyzer with careful control of operating
procedures.
Spray irrigation was used to test the efficiency of vegetation as a
concentration mechanism for the nutrients and toxic metals contained in polluted
leachate from a municipal solid waste sanitary landfill. Vegetation from six forage
grasses and six native woodland species was analyzed before and after application of
140 to 155 cm of leachate containing 500 ppm Ca; 150 to 200 ppm Na and Fe; 50
to 100 ppm of Mn, K, Mg, and N; 2 to 5 ppm of Al, Sr, Zn, and P; and less than
0.5 ppm of Ni, Co, Cr, Cu, Pb, and Cd. Measurements of chemical oxygen demand
(COD), specific conductivity, and pH in sprayed waste water were 5,000 mg/liter;
3,000 micromhos/cm; and 5.3 to 5.5, respectively. Leachate applications appreciably
increased Fe, Mn, Cl, and S in most forages and woodland species. Lime treatments
prevented excess Mn accumulation. Reed canarygrass contained higher levels of
micronutrients than other forages. Micronutrients in sourwood and orchardgrass
stands were depleted by leachate irrigation. Seasonal factors affected uptake of Na,
Fe, Mn, Zn, K, and Co in grasses. Volunteer Pennsylvania smartwood contained up
to 9,000 ppm Mn after irrigation with leachate. Heavy metals in grasses and
woodland species ranged from 10 to 30 ppm Cd; 1.0 to 7.0 ppm Ni; 3.0 to 6.0
208
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SLUDGE APPLICATION RATES
ppm Pb; and from 0.5 to 1.5 ppm Cr and Co. Aeration appreciably reduced the
odor and COD levels of leachate.
Studies to determine the effect of rates of sludge application on extremely
acid strip mine spoils (pH 3.2) have produced significant yield increases from tall
fescue, crambe, and other crops. Fescue forage was analyzed to determine quality
aspects as affected by harvest date and season of the year. Significant increases in
plant composition of Zn, Cd, Ca, and Mg were noted from applications of sewage
sludge. However, significant decreases were noted for B, Mn, Fe, Al, and Pb.
Significantly higher levels of Pb, Cu, Cr, Fe, Zn, Al, and N were found in
winter-harvested than in summer-harvested forage. Higher cadmium content may be
the main factor limiting forage quality where sewage sludge has been applied.
Cadmium concentrations in forage range from 0.9 ppm from conventional
fertilization on strip-mined areas to a high of 1.4 ppm where 224 MT/ha of sewage
sludge were applied. Crambe, an oil seed crop, showed significant increases in seed
yield from application of sewage sludge on low pH strip-mine spoil. An application
of 10 MT/ha of composted garbage on a newly seeded strip-mine spoil produced
significantly better tall fescue stands than treatments with lime or fluidized bed
waste plus a complete fertilizer. Old stands of fescue are better after 3 years on
plots receiving garbage mulch and sewage sludge than on plots receiving conventional
fertilizer and lime treatment. Fescue yields from older studies on strip mine spoils
increased with increasing rates of sludge to 224 MT/ha. Garbage mulch plus lime
also increased yields.
SEEDLING ESTABLISHMENT
SOIL CONSERVATION SERVICE
Studies were conducted at two locations to determine effects of sewage sludge
application rates on movement of various elements through an acid strip mine spoil
profile. Significant increases in soil pH at depths of 30 cm were found after
application of sludge. Calcium, Mg, P, K, Cu, and Zn were moved into the soil
profile, possibly by chelation with organic matter from sludge. Soil microbial studies
comparing plots treated with sewage sludge with conventionally fertilized strip mine
spoil indicated a much better soil microflora after treatment with sludge.
Seedling establishment of crested wheatgrass, western wheatgrass, and fourwing
saltbush was good at the Shirley Basin uranium mine site, and fair at the Rosebud
coal site in Wyoming. Residue production from spring-seeded barley averaged about
1120 kg/ha. Grass mixtures were seeded into the barley stubble in November.
Artemisia vulgaris, an introduced herbaceous sage, was found to have an average
protein content of 27 percent, and an in vitro digestability of 65 percent.
Phosphorus, Ca, Ma, and K contents of the plant material were within the optimum
range for cattle nutrition. Specific conductivity was usually below 2.0 mmhos/cm
and no sodic conditions were evident. All study sites were low in plant available P
and N; therefore, 56 kg N per hectare and 56 kg P per hectare were applied.
Plantings of woody species were expanded to include additional locations at
surface-mined sites at Kemmerer and Hanna, Wyoming, and at Oak Creek, Colorado.
Eighty-three woody species are now under test. Additional species were added to the
1-year plantings at Gillette, Shirley Basin, and Glenrock, Wyoming. Of the 83
species, only 18 planted at more than one location were not browsed by wildlife.
Major wildlife species causing damage were antelope and deer.
At Peoria, Illinois, translocation of Zn, Mn, Cu, Pb, Cr, Cd, and Hg was
studied in corn plants grown on strip-mine soil amended with anaerobically digested
sewage sludge. In the seven plant tissues analyzed, metal concentrations were
generally highest in the leaves and roots and lowest in the grain and cob.
Concentrations of all metals except Mn and Hg increased in tissues as a result of
sludge application.
The Soil Conservation Service has been involved in plant development work for
a long time. Many of the plants that are proving most effective in revegetating
surface-mined areas were selected by the SCS at one of its 20 plant material centers
around the country. In recent years, the SCS has greatly accelerated its activities in
evaluating, selecting, and encouraging the commercial development of plant materials
for surface-mined lands.
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DEPARTMENT OF ENERGY
PLANT MOISTURIZATION
The SCS system of classifying mine spoil has provided a method for evaluating
plants and correlating their adaptation and performance with site conditions to
project the results of their use on similar sites elsewhere. Technical guides have been
developed with information on the adaptation of plants, recommended mixtures,
seeding rates, and seeding times.
In addition to its plant materials work, the SCS has just completed an
inventory of land disturbed by surface mining in the United States as of July 1,
1977. The inventory covers the status of land needing reclamation, land not
requiring reclamation, and total acreages of land disturbed. Disturbed land is
classified by commodities mined. The report shows a total of 5.7 million acres
disturbed as of July 1, 1977. Of this, over 3.8 million acres have not been
reclaimed. This includes over 2.7 million acres mined before there was any legal,
requirement for reclamation. Approximately 1.9 million acres have been reclaimed
either by natural means or through efforts of mining companies and landowners.
The Department of Energy's Land Reclamation Program (LRP) was initiated In
1975 to conduct integrated research and development projects to coordinate,
evaluate, and disseminate the results of reclamation research. Close cooperation with
academic institutions and other agencies to transfer pertinent information and avoid
duplication of effort has been a primary goal. The major effort is to develop ways
of ameliorating the environmental impacts of coal extraction. Current field and
laboratory research efforts have been directed toward providing solutions to
problems related to land reclamation.
At the Big Horn Mine, Tongue River, Wyoming, scientists are investigating the
formation, transport, and ultimate environmental effects of mine-related pollutants in
the Tongue River watershed in Wyoming and Montana. The study will focus on
defining the effects of current strip mining practices and regulations as well as upon
predicting impacts on water quality.
The purpose of a study at the Jim Bridger Mine, Rock Springs, Wyoming, is
to investigate and evaluate alternative systems that can provide additional moisture
to plants used in revegetating mined land in the arid west. A new snowfence system
has been designed and deployed that has promise for increasing the water available
to vegetation. Two years' data indicate that plant-available moisture may be
increased by 20 percent to 50 percent.
ACID STUDY
REFUSE SITE
Other research at the Jim Bridger Mine is identifying principles of adaption
and survival of native species under stress. Plants are being tested and analyzed for
productivity (biomass), population dynamics (species mortality and distribution), and
energy allocation strategies (how a plant assigns its energy resources to growth,
reproduction, and defense).
A cooperative research/demonstration activity with the State of Illinois at
Goose Lake State Park is designed to investigate the process of acid production and
its transport into adjacent ponds and groundwater systems. This study is focused on
the groundwater system, including recharge, flow patterns, flow rates, discharge, and
chemistry, in the spoil materials and surrounding undisturbed areas. Information will
be gathered on (a) the chemical characteristics of groundwater in acidic mine spoils,
(b) the subsurface transport of potential pollutants to the ponds and surrounding
land area, (c) the magnitude of impacts to groundwater quality due to the initial
mining, and (d) the long-term effects of reclamation on groundwater, hydrology, and
quality. Additionally, oxygen diffusion rates into the spoils are being studied under
various surface treatments to determine .whether pyrite oxidation is controlled by
reclamation. Forty groundwater monitoring wells have been emplaced in the
reclaimed spoil material adjacent to undisturbed land to measure groundwater
transport of pollutants.
An abandoned 34-acre refuse area in south-central Illinois is the location of a
comprehensive reclamation/demonstration project. The refuse site has caused
pollution and sedimentation problems in nearby streams and also may have
contaminated the local groundwater system. The groundwater system and streams,
210
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WESTERN REVEGETATION
COSTS AND BENEFITS
SPOIL MATERIALS
ACID MINE DRAINAGE
and runoff from the gob pile, have been monitored before, during, and after the
reclamation in an attempt to understand the changes in water quality brought about
by reclamation. Additional research has been initiated at this site to investigate the
cost and effectiveness of selected reclamation techniques. In particular, the growth
of various plants in different concentrations of cover material and unamended and
treated gob is being evaluated in both field and laboratory experiments.
A joint study with Utah International Coal Company at the Navajo Mine is
concentrating on the breeding and selection of plant species and varieties for use in
the revegetation of lands disturbed by mining in the arid west. The objective of this
study is to develop plants suitable for reclaiming mine spoils in harsh environments
characterized by drought and spoil salinity. Seed and transplants from similar
environments were collected throughout the west for cytological studies, hybridiza-
tion, and cloning. Examinations have shown that most Atrip/ex species contain
chromosome races. This fact will assist in interpreting and utilizing adaptive
differences noted in native populations and in identifying the most promising crosses
in breeding studies.
At the Jim Bridger Mine in Wyoming and the Macoupin County refuse
reclamation/demonstration site in Illinois, research has been established to study the
use of reclaimed mine land by wildlife. Study areas have been designated where
species composition and density on reclaimed areas can be compared with those in
adjacent native ecosystems. A second study is focusing on the impacts small
mammals will have on early success of vegetation establishment. Early data suggest
that small mammals have a significant deleterious effect on reclamation.
Essential to any reclamation program is the identification and quantification of
factors responsible for variations in costs and benefits of the reclamation effort. A
project is underway to assess the realtive costs and benefits of alternate reclamation
procedures to determine possible methods of reducing overall costs while maintaining
acceptable end results.
Another project is set up for developing data and information systems
regarding techniques, technologies, and research in the field of mined land
reclamation, and the dissemination of such information. This activity is coordinated
with DOE's Energy Information Administration. This effort is focusing on designing
and implementing a land reclamation data acquisition and management system and a
comprehensive computerized bibliographic reference library.
For several years EPA has been engaged in studies of both eastern and western
coal mine reclamation. Results of the most recently completed studies on
reclamation are as follows:
Field experiments were established in western Kentucky on four types- of
surface-mined coal spoils. Areas were selected to represent the extremes in spoil
materials commonly encountered in reclamation. There is evidence that mine spoils
may be successfully reclaimed when proper levels of fertility have been restored.
Where a rough surface was created by ripping or subsoiling, yields of mixed
legume-fescue forage exceeded 4 metric tons per hectare. These yields were equal to
or greater than those of adjacent unmined land. The advantage was obtained at all
levels of applied phosphorus. The use of a chisel plow or heavy-duty disc produced
a rough micro-relief that also produced significantly greater forage yields than
smooth-graded plots.
It was found that phosphorus and water are commonly the limiting factors in
obtaining an adequate vegetative cover. Lime must be incorporated to effectively
improve the rooting zone of plants. Lime will not move downward, so plant roots
are restricted to the zone of lime incorporation.
A project was conducted near Elkins, West Virginia, to demonstrate methods
of controlling acid mine drainage (AMD) pollution from inactive surface and
underground coal mines. Methods included burial of acid-producing spoil and coal
refuse, and regrading and revegetation of surface mines.
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RUNOFF EFFECTS
RUNOFF QUALITY
SPENT SHALE DISPOSAL
The subwatersheds primarily impacted by surface mines showed the greatest
improvement. Although good vegetation was established on most areas, sulfate and
other ions continued to leach from the backfill material for years after reclamation
was completed.
Except for a few small areas, a good vegetative cover was established. Grasses
exhibiting the best growth were tall fescue, oat grass, orchard grass, and Kentucky
bluegrass. Weeping lovegrass was a good nurse crop. Sericea lespedeza, birdsfoot
trefoil, and alsike clover were the dominant legumes. Best tree survival and growth
was obtained from European black alder. Pines, Japanese larch, and black locust also
were successful. With the possible exception of the pines, dense growth of grasses
and legumes did not affect survival or growth of the trees. The addition of
agricultural lime and fertilizer was largely responsible for the success of vegetation.
At five active coal strip mine areas in the tristate region of Montana, North
Dakota, and Wyoming, a system of intensively monitored microwatersheds was
constructed to demonstrate the effects of several soil surface manipulation
treatments on control of runoff, chemistry of runoff, soil water flow, aquifer
characteristics, and vegetation establishment. Treatments were chiseling and gouging
with and without topsoiling and dozer basins with topsoiling.
Topsoiling is a major reclamation tool in the control of surface runoff because
it increases infiltration. For all storms observed, topsoiled watersheds had less runoff
than watersheds not topsoiled. Erosion at each study site correlated positively with
runoff. At this stage of the study it seems apparent that surface manipulation,
particularly gouging and dozer basins, is effective in controlling runoff and erosion
on many mine sites in the semiarid west.
At two of the study sites a net 10- to 20-cm of water moved from the
subsurface zone into the surface 2 m zone in four of the five watersheds during the
hydrologic year. If this process were to continue over decades there would be some
potential salinization of the surface soil.
Dozer basins should be constructed with a rear-mounted dozer basin implement
designed for that purpose. Front-blade equipment produces shallower basins with
lower water detention capacity and a very compact impermeable base.
The quality of surface runoff water from spoil watersheds is of major concern.
NO3-N, Mg, Ca, soluble salts, and most trace elements were found in, low
concentrations in runoff water. Mn and Fe concentrations often exceeded federal
standards for drinking water, but were probably acceptable for irrigation. Occasional
samples contained Cd, Pb, and PO^P at levels that exceeded desirable limits. Early
results of a study of the quality of runoff as a function of watershed surface
manipulations show no trends.
Surface manipulation treatments should be useful for controlling runoff under
most conditions in the semiarid west. However, if the conservation of soil water is
the goal, it will have variable results. At this stage of research, it is apparent that
surface manipulation techniques will be widely applicable, but there will be instances
when such techniques will have explicit limitations.
Disposal of massive amounts of spent shale will be required if an oil shale
industry using surface retorting is developed. Field studies utilizing lysimeters to
model both low elevation (dry) and high elevation (moist) disposal sites were
initiated in 1973 on two types of spent oil shale—coarse textured (USBM) and fine
textured (TOSCO). A similar study was initiated in 1975 on Paraho spent directly
heated oil shale. The studies were designed to document surface stability and salt
movement in spent shales and in spent shales covered with soil after vegetation had
been established by intensive treatment and then left under natural precipitation.
The Paraho study also provided for trace element analysis of the leachate water and
for comparison of water movement through compacted and uncompacted spent
shale.
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RESALINIZATION
PLANNING MODEL
A good cover of native perennial grasses was established on all plots except
the low elevation bare TOSCO spent shale, where the cover was dominated by a
mixture of annual and perennial grasses. The bare Paraho plots had less than 10
percent vegetative cover. Problems encountered included inadequate leaching prior to
planting, resalinization by upward movement of salts into the soil cover over the
fine textured TOSCO spent shales, and the initial high pH of the Paraho spent
shales. Vegetation from the plots showed higher levels of some trace elements than
vegetation grown on native soil. Runoff from all plots was moderately to highly
saline. Sediment yields were generally low.
If spent oil shales are to be quickly stabilized with native vegetation they will
require leaching, N and P fertilization, and irrigation. Nitrogen application will be
required for a number of years to assure a permanent cover.
The infiltration rate on the fine-textured spent shale is very slow, thus the
erosion potential may be high. The slow infiltration rate must be considered when
stabilization of this spent shale is planned.
Resalinization of leached fine-textured spent shale occurred in these studies.
Application of more leach water would move the salt farther down and decrease the
resalinization potential. The disposition of the leach water within the spent shale
disposal pile must be considered in large-scale operations.
A minimum of 30 cm of soil should be used over unleached spent shale with
low pH. High pH [11-12] spent shales require a thicker soil cover. Even with soil
cover, irrigation and fertilization are still required for vegetation establishment.
A study of ecological recovery after reclamation of toxic coal mine spoils
measures the rate of recovery of a damaged ecosystem in response to intensive
remedial treatments. The project involves a problem watershed in which 162 ha (400
acres) of forested land were disturbed in the early 1970s. Unsuccessful reclamation
resulted in adverse impacts to the 27.6 km (10.8 sq. mi.) watershed.
Remedial work conducted over a 3-year period was initiated during the fall of
1974. Treatments included incorporation of agricultural limestone to raise spoil pH,
seeding with acid-tolerant grasses and legumes to provide a protective ground cover,
and planting of trees and wildlife shrubs the following planting season.
Vegetation and aquatic monitoring began in 1975. Data collected through
spring 1977 show that total vegetative ground cover increased from 34 percent to
43 percent, and that the mean pH increased from 4.0 to 4.5. Aquatic invertebrate
sampling indicates an increase in the number of individuals and taxa in the streams
receiving direct treatment. Fish have recovered in portions of the main stream close
to two downstream reservoirs. The most evident changes in water chemistry were
overall increases in stream pH. Other water quality parameters varied in their
responses to the treatment.
Tennessee Valley Authority (TVA) is currently developing a planning model
for assessing the impact of surface mining on the environment. Findings of field
studies at 12 sites in the Cumberland Plateau of Tennessee indicate that:
• Most mining results in alkaline drainages with generally low concentrations
of metals.
• The most serious water quality problem is erosion and resulting
sedimentation.
• Models for daily streamflow, storm flow, and suspended solids have been
formulated and at least partially verified.
• Models for stream biota and stream pH have been formulated but not
verified.
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PEST AND VECTOR FORMATION Another project involves arthropod pests and vectors produced in pools formed
as part of the strip mining process. Monthly biological samples have been collected
from nine study ponds (selected on the basis of age) and likely sites for oviposition
near the ponds. Seven species of mosquitoes, five of which actively feed on man,
have been found. Anopheles punctipennis and Culex erraticus have been the most
prevalent species, and Anopheles quadrimaculatus, the malaria vector, was found in
significant numbers.
Midges of the genus Procladius (Diptera:Chironomidae) are common inhabitants
of ponds, lakes, and slow-flowing streams. Larvae with morphological abnormalities
were found in ponds formed by strip mining for coal near Brilliant, Marion County,
Alabama. Atrophied and deformed antennae, deformed mandibles, and unusual
numbers and forms of ligular teeth appeared in about 25 percent of the nearly 200
larvae examined. A search is being conducted for the factor or factors causing the
abnormalities; the following are possibilities; crowding, diet, water quality, and
nematode parasitism.
SUMMARY Vegetation can be successfully established on most surface mine spoils if
proper mining and reclamation techniques are employed. Overburden must be moved
and placed so that the best material for plant growth is on the surface. A suitable
seedbed is essential. Amendments must be used to alleviate acidity, provide
nutrients, and improve plant-soil-water relations. Seeding or planting must be done at
the proper time of the year. Species must be compatible with the area. Species in
mixtures must be compatible with each other to assure success in achieving land
reclamation goals.
Legislation generally determines the degree of reclamation sought, but
technology is not always available to meet regulatory requirements. Sometimes
legislative action tends to create new problems through specific requirements which
have not been thoroughly researched.
Much research is being done under the auspices of the federal government
aimed at reclamation of surface mined lands throughout the United States.
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References
1. Lyle, E. S., Jr., D. T. Janes, D. R. Hichs, and D. H. Weingartner. 1976. Some
vegetation and soil characteristics of coal surface mines in Alabama. In Proc.
4th Symp. Surf. Min. Reclam. Oct. 19-21, Louisville, Ky. Natl. Coal Assoc.,
Washington, D.C. p. 140-152.
2. Kohnke, H. 1950. The reclamation of coal mine spoils. In A. G. Norman (ed.)
Adv. Agron. 2:317-349. Academic Press, New York.
3. Lane, R. D. 1968. Forest Service reclamation research. Min. Cong. J. 54:38-42.
4. Limstrom, G. A. 1960. Forestation of strip-mined land in the central states.
U.S. Dep. Agric. Handb. 166. U.S. Gov. Print. Off., Washington, D.C.
5. Tyner, E. H., and R. M. Smith. 1945. The reclamation of the strip-mined coal
lands of West Virginia with forage species. Soil Sci. Soc. Am. Proc.
10:429-436.
6. Massey, H. F. and R. I. Barnhisel. 1972. Copper, nickel and zinc released from
acid mine spoil materials of eastern Kentucky. Soil Sci. 113:207-212.
7. Wiram, V. P., and J. A. Deane. 1974. Physical and chemical characteristics of
acid-producing sandstone warrant preferential strip and burial mining methods.
In Proc. 5th Symp. on Coal Mine Drainage Res. Natl. Coal Assoc., Washington,
D.C.
8. LeRiche, H. H. 1959. The distribution of certain trace elements in the lower
lias of southern England. Geochim. et Cosmochim. Acta 16:101-127.
9. Swanson, V. E. 1961. Geology and geochemistry of uranium in marine black
shales; A review. U.S. Geol. Surv. Prof. Pap. 356-C.
10. Nicholls, G. D. and H. H. Loring. 1962. The geochemistry of some British
carboniferous sediments. Geochim. et Cosmochim. Acta 26:181-233.
11. Curtis, C. D. 1966. The incorporation of soluble organic matter into .sediments
and its effect on trace-element assemblages. In G. D. Hobson and M. S. Louis
(eds.) Advances in organic geochemistry, p. 1. Pergamon Press.
12. Deely, D. J. and F. Y. Borden. 1973. High surface temperature on strip-mine
spoils. In R. J. Hutnik and G. Davis (eds.) Ecology and reclamation of
devastated land, Vol. 1:67-79. Gordon and Breach, New York.
13. Laude, H. M. 1964. Plant response to high temperatures. In Forage plant
physiology and soil-range relationships. Spec. Publ. No. 5, p. 15-31. Am. Soc.
Agron., Madison, Wis.
14. Rogers, N. R. 1951. Strip-mined lands of the western interior coal province.
55 pp. Mo. Agric. Exp. Stn. Bull. 475.
215
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15. Einspahr, D. W. 1955. Coal spoil-bank materials as a medium for plant growth.
Ph.D. thesis, Iowa State Coll. 197 pp.
16. Schramm, J. E. 1966. Plant colonization studies on black wastes from
anthracite mining in Pennsylvania. Am. Philos. Soc. Trans. N.S. 56 (Part
17. Marx, D.H. 1976. Use of specific mycorrhizal fungi on tree roots for
forestation of disturbed lands. Proc. Conf. Forestation Disturbed Surface Areas.
p. 47-65.
18. Daft, M.J. and E. Hacskaylo. 1976. Growth of endomycorrhizal and
nonmycorrhizal red maple seedlings in sand and anthracite spoil. For Sci.
23(2):207-216.
19. Aldon, E. F. 1975. Endomycorrhizae enhance survival and growth of fourwing
saltbush on coal mine spoils. USDA For. Serv. Res. Note RM-294.
20. Marx, D. H. 1975. Mycorrhizae and establishment of trees on strip-mined land.
Ohio J. Sci. 75:288-297.
21. Rothwell, F. M. 1973. Modulation by various strains of Rhizobium with
Robinia pseudoacacia seedlings planted in strip-mine spoil. In R. J. Hutnik and
G. Davis (eds.) Ecology and reclamation of devastated land, Vol. 1:349-355.
Gordon and Breach, New York.
22. Trappe, J. L 1977. Selection of fungi for ectomycorrhizal inoculation in
nurseries. Annu. Rev. Phytopathol. 15:203-222.
23. Smith, S. E. and M. J. Daft. 1977. Interactions between growth, phosphate
content and nitrogen fixation in mycorrhizal and non-mycorrhizal (Medicago
sativa). Austr. J. Plant Physiol. 4(3):403-414.
24. Vogel, W. G. 1975. Requirements and use of fertilizer, lime and mulch for
vegetating acid mine spoil, p. 152-170. In Proc. 3rd Symp. on Surf. Min. and
Reclam. Oct. 21-23, Louisville, Ky. Natl. Coal Assoc., Washington, D.C.
25. Power, J. F., R. E. Ries, F. M. Sandoval, and W. 0. Willis. 1975. Factors
restricting revegetation of strip-mine spoils. Proc. Fort Union Coal Field Symp.,
W. F. Clark (ed.), Mont. Acad. of Sci., Billings, Mt. p. 336-346.
26. Doering, E. J. and W. 0. Willis. 1975. Chemical reclamation of sodic strip-mine
spoils. USDA-ARS-NE-20. 8 pp.
27. Vogel, W. G. 1974. All-season seeding of herbaceous vegetation for cover on
Appalachian strip-mine spoils, p. 175-186. In Proc. 2nd Res. Appl. Technol.
Symp. Min. Land Reclam. Oct. 22-24, Louisville, Ky. Natl. Coal Assoc.,
Washington, D.C.
28. Armiger, W. H., J. N. Jones, Jr., and 0. L. Bennett. 1975. Rock phosphate as
an acid mine spoil vegetation. Proc. South. Assoc. Agric. Sci. p. 79-84.
29. Vogel, W. G. 1973. The effect of herbaceous vegetation on survival and growth
of trees planted on coal-mine spoils, p. 197-207. In Proc. Res. and Appl.
Technol. Symp. Min. Land Reclam., Mar. 7-8, Pittsburgh, Pa. Bitum. Coal Res.,
Inc., Monroeville, Pa.
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control technology
chapter 5
i
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CHAPTER CONTENTS
control technology
INTERAGENCY COAL CLEANING TECHNOLOGY DEVELOPMENTS
James D. Kilgroe, US EPA «>oi
Richard E. Hucko, Department of Energy 221
FLUE GAS DESULFURIZATION OF COMBUSTION EXHAUST GASES
Norman Kaplan, US EPA **e-»
Michael A. Maxwell, US EPA 253
DISPOSAL OF POWER PLANT WASTES
Julian W. Jones, US EPA 275
CONTROL OF NITROGEN OXIDES FROM COMBUSTION
George Blair Martin, US EPA
Joshua S. Bowen, Jr., D.Eng., US EPA 291
FLUIDIZED BED COMBUSTION
Steven I. Freedman, Ph.D., Department of Energy 313
CONTROL OF PARTICULATES FROM COMBUSTION
Dennis C. Drehmel, Ph.D., US EPA «»*»«*
James H. Abbott, US EPA 323
PANEL DISCUSSION:
Frank T. Princiotta, US EPA
H. William Elder, Tennessee Valley Authority
Kurt E. Yeager, Electric Power Research Institute
John A. Belding, Ph.D., Department of Energy
Marvin I. Singer, Department of Energy
QUESTIONS & ANSWERS 343
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CONTROL TECHNOLOGY
INTERAGENCY COAL CLEANING
TECHNOLOGY DEVELOPMENTS
James D. Kilgroe
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Richard E. Hucko
Coal Preparation and Analysis Laboratory
Department of Energy
COAL CLEANING
THREE BASE ELEMENTS
AIR POLLUTION REGULATIONS
Expanding coal production and use is a major goal of our National Energy
Policy. A corollary goal is the containment of adverse environmental effects from
coal use.
Important in the coal energy cycle is coal beneficiation or cleaning. Coal
cleaning removes extraneous mineral matter and mining residue. It is also a cost
effective means of removing sulfur from metallurgical coke and boiler fuels used to
comply with SC>2 emission regulations.
Coal cleaning processes generate pollutant streams which must be controlled
and residues which must be disposed of in an environmentally sound manner. In
1976, more than 370 million tons* of coal were physically cleaned, generating more
than 107 million tons of coal cleaning residues. Leachates from improper waste
disposal, particulate emissions from thermal drying, and fugitive dust from coal
handling pose health and ecological threats.
EPA's interagency energy/environmental program is subdivided into three basic
elements. The principal objectives of activities under these subprograms are to (a)
assess and develop coal cleaning technology for removing pollutant-forming
contaminants from coal, (b) evaluate the environmental impacts of coal cleaning
processes, and (c) develop improved methods of controlling pollution from coal
preparation.
This paper presents an overview of regulatory activities related to coal cleaning,
an analysis of future coal cleaning R&D priorities, and a summary of progress on
the interagency coal cleaning R&D program.
Research and development activities under the interagency coal cleaning
program are responsive to changing regulatory requirements and energy goals. A
review of the technical status of coal cleaning and associated regulatory activities
will provide the context for the discussion of progress on recent coal cleaning R&D.
In accordance with provisions of the Clean Air Act Amendments of 1970,
EPA has set primary and secondary ambient air quality standards which regulate
pollutant levels to protect human health and public welfare (property and plant and
animal life). Ambient air pollutants specified in current EPA regulations relating to
coal use include sulfur oxides, nitrogen oxides, and total suspended particulates.
Section 1.11 of the 1970 Clean Air Act Amendments requires that EPA
promulgate emission standards for new stationary sources (constructed after the date
the regulations are proposed). Since these new source performance standards (NSPS)
are based on emissions, the owner/operator may use any control system, but the
standard must be achieved without the privilege of variances or exemptions. The
Clean Air Act Amendments of August 1977 have significantly modified previous
*English to metric unit conversion factors are given at the end of this paper.
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NSPS FOR FOSSIL
FUELED BOILERS
WATER POLLUTION
REGULATIONS
clean air legislation, especially as related to its potential impacts on the use of coal
cleaning technology. These Amendments specify that all new stationary sources
regulated by EPA must (a) use best available control technology, (b) use a method
of continuous pollution control, and (c) achieve a percentage reduction of the
regulated pollutants for fossil fuel fired units. Any reduction of a pollutant by post
extraction fuel processing may be credited to the percentage reduction requirement.
In the near future, EPA will propose revised NSPS for fossil fueled boilers
used for electrical energy generation. The regulations now under consideration (a)
require an 80- to 90-percent reduction in sulfur between extraction and stack gas
emissions and (b) specify that the sulfur emissions cannot exceed 1.2 Ib
Btu of boiler heat input. Emissions below a minimum level (0.2 to 0.5 Ib
Btu) would be exempted from the percentage reduction requirement. Promulgation
of these regulations would effectively preclude the use of coal cleaning as a sole
method for complying with S02 standards in new electric utility boilers.
Other important provisions of the 1977 Clean Air Act Amendments include
prevention of significant deterioration of air quality in clean air regions, the siting of
sources in nonattainment areas, the periodic review of state implementation plans for
meeting National Ambient Air Quality Standards, and the setting of emission
standards for potentially hazardous pollutants. The strigency of regulations for
nondeterioration and clean air regions may necessitate the use of coal cleaning in
combination with scrubbing in order to comply with SO2 emission standards.
Tightening and strict enforcement of emission standards under state implementation
plans may expand the market for physically or chemically cleaned coals.
Potentially hazardous pollutants which EPA must consider regulating include
arsenic, beryllium, mercury, lead, and polycyclic organic matter, all of which are
emitted from coal-fired boilers. If EPA decides that the emission of these pollutants
from coal combustion must be regulated, then removal of some of these
contaminants before combustion by coal cleaning may be an effective method of
control.
Federal control of water pollution sources associated with coal production,
preparation, and consumption is achieved through the issuance of discharge permits
which contain the limits on the effluents discharged. Effluent guidelines are
presently based on the best practicable control technology (BPT) currently available
and must be based on the best available technology economically achievable
(BATEA or BAT) by 1983, except where modified requirements are in order,
pursuant to Section 301 (c) of the Federal Water Pollution Control Act (FWPCA).
Effluent limitations are also being issued for new sources. These new source
performance standards, mandated by FWPCA Section 306, are intended to be the
most stringent standards applied.
State control of water pollution sources associated with coal preparation is
achieved through the issuance of permits independently or under the National
Pollutant Discharge Elimination System (NPDES). The permits, which contain limits
on the effluents discharged, are issued to each discharger. The objective of such
control systems is to achieve or maintain specified ambient water quality standards
which are primarily a state responsibility. The Federal laws are intended to aid in
the achievement of state standards. EPA, however, retains the authority to veto state
plans.
On May 13, 1976, EPA promulgated interim final effluent guidelines for four
subcategories of existing sources: coal preparation plants; coal storage, refuse storage,
and coal preparation plant ancillary areas; acid or ferruginous mine drainage; and
alkaline mine drainage. More than 10 lawsuits were filed challenging these
regulations. These lawsuits were consolidated and are now pending before the U.S.
Court of Appeals for the Fourth Circuit.
FINAL REGULATIONS
EPA promulgated final regulations on April 26, 1977, which incorporated
several revisions to the interim final effluent guidelines published on May 13, 1976.
Subpart B of these regulations addresses discharges from coal preparation plants and
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associated areas, including discharges which are pumped, siphoned, or drained from
coal storage, refuse storage, and coal preparation plant ancillary areas. Included
under these regulations are discharges related to the cleaning or beneficiation of coal
of any rank including, but not limited to, bituminous, lignite, and anthracite.
LIMITATIONS
The limitations establish the- concentration of pollutants which may be
discharged after the application of BPT treatment. These limitations differ for
discharges that are normally acidic before treatment as opposed to those that are
normally alkaline. For acidic conditions, limitations were specified for total iron,
manganese, total suspended solids (TSS), and pH. Limitations for total iron, TSS,
and pH were specified for alkaline conditions.
On September 17, 1977, EPA published proposed new source performance
standards for the coal mining point source category. These limitations establish the
concentrations of the pollutants which may be discharged after application of the
best available demonstrated control technology. These limitations apply to discharges
from facilities which recycle process waste water and differ depending upon whether
discharges are normally acidic or alkaline before treatment. Pollutants regulated
include total iron, manganese (acidic conditions only), TSS, and pH. The regulations
stipulate no discharge from facilities which do not recycle process waste water.
In 1975, EPA was taken to court by several environmental groups who
claimed that EPA had not done a complete job in assessing the pollution of surface
waters by industry. On June 7, 1976, the courts decided in favor of the
environmentalists, and the machinery for a review of effluent guidelines was set in
motion.
PRIORITY POLLUTANTS
EPA must first review its BAT guidelines in the light of the priority
pollutants. These priority pollutants arose from the court case and amounted to
about 65 compounds or classes of compounds which the EPA had failed to regulate,
or take into consideration, in their earlier guidelines. The process of naming specific
compounds in the classes resulted in a list of 129 priority pollutants. The courts, in
this decision, set deadlines for EPA to implement BAT by 1983. The first step is a
proposed rule-making by September 30, 1978. By December 31, 1978, after time
for comment, EPA is to publish its proposed revised guidelines. Six months later
(June 30, 1979) the revised guidelines are to be promulgated. This will give industry
4 years to implement BAT. The recent 4 month strike by the United Mine Workers
(UMW) of America has interfered with this schedule. Consequently, EPA, along with
the National Coal Association, is preparing to ask the court for a 6-month delay in
the deadlines.
The BAT Review is a three phase study—the first two deal with technology;
the third, with economics. The technology phases centered on the priority pollutants
and are known as the screening and verification phases. The screening phase involves
looking for the presence or absence of the priority pollutants; the verification phase
involves quantifying and confirming the pollutants found in screening.
ECONOMIC PHASE
SCREENING PHASE
During these two phases, economic data are also collected. Factors which
would affect the economics of a treatment technology are determined from each site
visited for sampling as well as from industry associations. These factors include,
plant capacity, plant age, location, type of process, source of raw materials, end use
of product, capital cost, capital recovery, and operating costs. This information is
combined with wastewater data, flow rates, and concentrations, to assess the impact
and cost effectiveness of a treatment technology.
The verification phase was delayed by the UMW strike. Plans are being made
to begin the verification phase.
The screening phase has been completed for the coal mining industry. In the
screening phase, 18 coal preparation plants were visited. Of these only two were not
sampled-one because the plant was shut down by a strike; and the other because
there was no point of discharge.
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SOLID WASTE DISPOSAL
REGULATIONS
In addition to the screening tests for the 129 priority pollutants, analyses were
made for classic water pollutant parameters and some elements not on the priority
pollutant list. Of the 129 priority pollutants, 24 were found in water from
preparation plants and associated areas. Some of the pollutants may be artifacts of
the analytical procedures. Additional tests will be required to evaluate their
authenticity. Also, 12 elements not on the priority pollutants list were found.
Solid wastes generated from coal preparation are generally subject to land
disposal. Federal guidelines for land disposal of solid wastes are nonspecific in terms
of definite quantities which can or cannot be disposed of. All facets pertaining to
land disposal sites are covered by requirements to conform to the most stringent
water quality standards under the provisions of the Federal Water Pollution Control
Act. Leachate collection and treatment systems are required at disposal sites as
necessary to protect ground and surface water resources.
Provisions of the Solid Waste Disposal Act were significantly modified by the
passage, on October 21, 1976, of the comprehensive Resource Conservation and
Recovery Act (RCRA) of 1976 (P.L. 94-580). From 90 days to 2 years was
provided for consummation of many of the actions called for by the Act; therefore,
details of regulations to be promulgated are not yet available. Some of the general
provisions of the Act are:
• EPA must issue guidelines within 1 year, defining sanitary land fills as the
only acceptable land disposal method that can be implemented; open dumps
are to be prohibited.
• Within 1 year, EPA shall develop and publish proposed guidelines for solid
waste management.
• Within 18 months, EPA must propose criteria for identifying hazardous
waste, regulations for generators of hazardous wastes, regulations for
transporters of hazardous wastes, and performance standards for treatment,
storage, and disposal of hazardous wastes.
• Under minimum guidelines to be provided by EPA, the states will manage
permit programs.
• Each regulation promulgated shall be reviewed and, where necessary, revised
at least every 3 years.
CONTENT OF COAL
ORGANIC AND INORGANIC
AFFINITIES
It has not yet been determined whether coal refuse (and combustion ash) will be
classified as hazardous wastes. This determination would require implementation of
the most restrictive provisions of the Act.
Coal is a complex heterogenous substance. In addition to its organic
constituents (carbon, hydrogen, oxygen, and nitrogen) coal contains significant
quantities of inorganic elements. While these inorganic elements are associated
primarily with individual mineral phases in coal, they are also incorporated to a
lesser degree in the complex organic coal molecules.
Coals are known to contain nearly all of the naturally occurring elements.
Some elements of environmental concern contained in significant quantities in coal
are sulfur, arsenic, beryllium, cadmium, copper, lead, mercury, manganese, nitrogen,
selenium, and zinc (1).
Elements of environmental concern may be classified by their relative organic
or inorganic affinities. Those with high organic affinities are associated predomi-
nantly with the organic coal structure, while those with high inorganic affinities are
associated predominantly with the coal mineral phases. Physical and chemical coal
preparation partition the elements of environmental concern in to fractions which
are associated with clean coal product streams or waste or pollutant emission
streams.
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PHYSICAL COAL CLEANING
CLEANING STEAM COAL
POLLUTANT LEACHATE
SPENT CHEMICALS
The relative amounts of contaminants, the manner in which they are included
in the coal structure, and the degree to which they can be removed vary widely
with different coals.
Coal is physically cleaned by crushing run-of-the-mine coal to a point where
some of the mineral impurities are released from the coal structure. The mineral and
coal particles are then separated by techniques which generally rely upon differences
in the specific gravity or surface properties of the particles.
Chemical coal cleaning processes are being developed to provide improved
techniques for desulfurizing steam and metallurgical coals. Chemical coal cleaning
processes vary substantially because of the different chemical reactions which can be
used to remove sulfur and other contaminants from coal. Chemical coal processes
usually entail grinding the coal to small particles and reacting these particles with or
without chemical agents at elevated temperature and pressures. The sulfur in coal is
converted to elemental sulfur or sulfur compounds which can be physically removed
from the coal structure. Some chemical leaching processes, such as the TRW—Meyers
Process, remove only pyritic sulfur. Other processes, such as that under development
by the Department of Energy (DOE), are said to be capable of removing organic
and pyritic sulfur.
Approximately 50 percent of the domestically consumed coal is physically
cleaned to remove mineral matter and mining residue. A large portion of
metallurgical grade coals are cleaned to remove sulfur. Cleaning operations for steam
coals have not previously been designed to remove sulfur for compliance with SO2
emission standards. The first U.S. steam coal preparation plant, designed to remove
sulfur for compliance with state and federal S02 emission standards, has just begun
operation at Homer City, Pennsylvania. Two other sulfur removing plants are being
planned by the Tennessee Valley Authority (TVA). None of these steam coal plants
incorporate the advanced beneficiation techniques now used in the metallurgical and
mineral industries.
A number of chemical coal cleaning processes are currently under development
(2). These processes are being developed to produce desulfurized coals for use in
complying with S02 emission standards. The Meyers chemical coal cleaning process,
which is at the most advanced development stage, is now being evaluated in a
1/3-ton per hour test unit at Capistrano, California. At least eight other processes
are in various stages of laboratory development. Many of these are capable of
removing both organic and pyritic sulfur. With accelerated development, several
chemical processes could be ready for commercial demonstration in 5 to 10 years.
Coal preparation plants annually generate more than 100 million tons of waste.
Interaction of air and water in pyrite rich coal wastes converts the pyritic sulfur to
a dilute sulfuric acid leachate. This leachate may have high concentrations of
dissolved trace elements or other potentially hazardous pollutants (3). Drainage of
the leachate into ground and surface waters may degrade water quality and affect
human health. Current knowledge on the relationships between coal mineral
properties, coal trace element concentrations, the effects of weathering on the
release of trace elements, and the effects of various technologies in controlling trace
element pollution is rudimentary.
Coal and mineral dust, resulting from the handling, transportation, and storage
of coal, may contain high concentrations of hazardous trace elements and
compounds. Little is known about the composition of these dusts, their effects on
human health, and the degree to which dust emissions can be controlled.
Sludges from coal preparation plants present a disposal problem. Some sludges
are not easily dried, are thixotropic, and must be contained in storage ponds.
Techniques to solidify and dispose of coal preparation plant sludges are in an early
stage of development.
Spent chemicals used in chemical desulfurization contain many potentially
hazardous trace elements and compounds. Little is known about the techniques
which will be needed to neutralize and dispose of these wastes.
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DEVELOPMENT DIRECTIONS
PERIODIC REVIEW
OF STANDARDS
A primary short-term market for coal cleaning has been created by SC^ air
pollution control requirements. The degree to which coal cleaning is used to meet
these requirements depends upon the specific sulfur emission standards which must
be met, the desulfurization potential of U.S. coals, the costs of coal cleaning, and
the costs of alternative pollution control techniques. Other applications for coal
cleaning include the upgrading of subbituminous coals (principally lignite) and the
preparation of coals for synthetic fuel conversion processes. The primary objective of
the interagency coal cleaning program has been directed toward the environmental
considerations of coal use.
The applicability of coal cleaning for compliance with S02 emission standards
is contingent upon a number of regulatory and technical uncertainties. Once these
uncertainties have been resolved, the use of coal cleaning will be largely defined by
market considerations; i.e., a determination of the most cost effective method of
coal energy production considering the costs of all pollution control requirements.
Near-term applications for compliance with S02 emission standards are in doubt
primarily because of changing regulatory requirements mandated by the 1977 Clean
Air Act Amendments.
The 1977 Clean Air Act Amendments require periodic review of emission
standards under State Implementation Plans (SIPs). Some regulations will be
tightened, especially in noncompliance regions and in areas wishing to offset
emissions from industrial growth by a reduction of emissions from existing boilers.
Revised NSPS for utility boilers being considered by EPA require an 80
percent to 90 percent reduction in sulfur between extraction and emission. This
would preclude physical coal cleaning as a sole method for compliance with SC>2
emission standards in these boilers. In some instances combinations of coal cleaning
and flue gas desulfurization (FGD) may be more cost effective than FGD alone.
Cases for which this combination may be the most cost effective strategy cannot be
adequately defined because of economic uncertainties. The standards have not been
promulgated and a number of potential cost benefits and liabilities associated with
coal cleaning have not been quantified. These include (a) the emission averaging time
which must be used, (b) the degree to which coal cleaning will reduce coal sulfur
variability, (c) the comparable costs for controlling sulfur variability with scrubbers,
and (d) boiler operating and maintenance cost benefits resulting from coal cleaning.
EPA also plans to set BACT standards for industrial boilers. The level at which
these standards are set will determine the applicability of coal cleaning as an SC>2
emission control strategy in these boilers.
Taking the above factors into consideration, along with the current status of
coal cleaning technology, near and long term problems which coal cleaning R&D
must resolve may be projected:
NEAR TERM PROBLEMS
The characterization of coal sulfur variability and the degree to which coal
preparation attenuates this variability.
The desulfurization potential of U.S. coals by physical methods, including
techniques which rely on surface properties as well as specific gravity
differences.
The development of improved fine coal cleaning techniques which will
provide for maximum pyrite removal with minimum coal energy losses.
The development of improved techniques for fine coal dewatering and
drying.
An evaluation of the environmental impacts which result from coal cleaning.
The development of technology to control trace elements in leachant from
coal preparation plant wastes.
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• A determination of the effects of coal cleaning on boiler operating and
maintenance costs.
• The establishment of costs for controlling pollution from coal preparation
processes.
• The establishment of costs of alternative strategies for compliance with S02
emission standards in industrial and utility boilers.
LONG TERM PROBLEMS
• The characterization of U.S. coals and their mineral and organic
contaminants,
R&D PROGRESS
• The development of advanced physical/chemical processes for removing
inorganic and organic contaminants in coal.
• The development of pollution control techniques for (a) newly regulated
pollutants, and (b) developing coal cleaning technologies.
The interagency coal cleaning program is divided into three major subprograms:
1) the assessment and development of coal cleaning processes, 2) the assessment of
environmental impacts from coal cleaning, and 3) the development of pollution
control technology for coal cleaning processes. Government organizations involved in
the program include the U.S. Environmental Protection Agency, the Department of
Energy, the Department of Interior, and the Tennessee Valley Authority. The
program budget for fiscal 1978 was approximately $8.0 million. The program is
directed for EPA by the Industrial Environmental Research Laboratory, Research
Triangle Park, North Carolina. Table 1 summarizes projects active during 1977-1978.
Selected projects are discussed in the following sections.
TABLE 1
Active interagency coal cleaning projects (1977-1978)
Project Title (Contract, Grant, or
Interagency Agreement)
Organization
Directing
Work
Organization
Performing
Work
Objectives
TECHNOLOGY ASSESSMENT AND DEVELOPMENT
Coal Cleanability (IAG-D6-E685)
Coal Cleaning Technology Assessment
and Development (68-02-2199)
Interim Support for Homer City
Test Program (68-02-2639)
Dense Media Cyclone Pilot Plant (IAG-D6-E6S5)
Demonstration of Coal-Pyrite Flotation
(IAG-D5-E685)
Adsorption-Desorption Reactions in
Pyrite Flotation (IAG-D6-E685)
High Gradient Magnetic Separation
(IAG-D5-E686)
Surface Phenomena in Dewatering of
Fine Coal (IAG-D5-E685)
Coal Cleaning Test Facility
(IAG-D5-E685)
DOE1
EPA/DOE
-------
TABLE 1 (continued)
Project Title (Contract, Grant, or
Interagency Agreement)
Organization
Directing
Work
Organization
Performing
Work
Objectives
Coal Preparation Plant Computer Model
(IAG-D6-E685)
Engineering/Economic Analysis of Coal
Preparation Operation and Cost
(IAG-D6-E685)
Reactor Test Project for Chemical Removal
of Pyntic Sulfur from Coal (68-02-1880)
Microwave Desulfunzation of Coal
(68-02-2172)
Battelle Hydrothermal Process Improvement
Studies (68-02-2187)
Evaluation of Chemical Coal Cleaning
Processes (IAG-D5-E685)
Hydrodesulfunzation of Coal (68-02-2126)
Environmental Studies on Coal Cleaning
Processes (I AG-D5-E7211
Cost Evaluations of Coal Cleaning and
Scrubbing (IAG-D5-E721)
EPA/DOE1
DOEr)
EPA
EPA
EPA
DOE*
EPA
EPA
EPA
DOE1 ', U. of
Pittsburgh, and
Battelte
Hoffman-Munter
Corp.
TRW Defense and
Space Systems Group
General Electric
Battelle Columbus
Laboratories
Bechtel
Institute of Gas
Technology
Tennessee Valley
Authority (TVA)
Develop computer model capable of predicting the
performance of coal preparation plants.
Determine the costs of cleaning for eight repre-
sentative coal preparation plants - from
jig plants to complex heavy media plants.
Evaluation of the Meyers chemical coal cleaning
process in a 1/3 tph test reactor unit.
Evaluate the feasibility of coal desulfurization
by microwave treatment.
Evaluate methods for liquid/solid separation and
leachant regeneration.
Evaluate relative costs and performances of
selected chemical coal cleaning processes.
Evaluate desulfurization of coal by mild oxi-
dative treatment followed by devolatihzation.
Evaluate technology for controlling pollution
at TVA coal preparation plants.
Evaluate relative costs of coal cleaning and
scrubbing in complying with various SO2 emission
ENVIRONMENTAL ASSESSMENT
Environmental Assessment of Coal Cleaning
Processes (68-02-2163)
EPA
Battelle Columbus Evaluate pollution resulting from coal cleaning,
Laboratories transportation and storage. Evaluate coal
cleaning as an SO2 emission control technique.
Trace Elements and Mineral Matter in
U.S. Coals (R804403)
Geology of Contaminants tn Coal
(IAG-D6-E685)
Trace Element Characterization of Coal
Preparation Wastes (IAG-D5-E681)
A Washabihty and Analytical Evaluation
of Potential Pollution from Trace
Elements (IAG-D6-E685)
Evaluation of the Effects of Coal Cleaning
on Fugitive Elements (IAG-D6-E685)
DOE
DOE
Illinois State
Geological Survey
U.S. Geological
Survey
Los Alamos Scienti-
fic Laboratory (LASL)
DOEr)
Bituminous Coal
Research Inc.
Characterize the elemental constituents and
mineralogy of U.S. coals.
Characterize coal resources west of the
Mississippi as to their elemental and miner-
alogic composition. Evaluate the geologic
factors which affect or control coal cleana-
bility.
Characterize trace element and mmeralogic
associations in coal preparation wastes.
Evaluate partitioning of trace elements in 10
U.S. coals during specific gravity separation.
Evaluate partitioning of trace elements during
preparation and use.
DEVELOPMENT OF POLLUTION CONTROL TECHNOLOGY
Control of Trace Element Leachmg from EPA/DOE*''
Coal Preparation Wastes (IAG-D5-E681)
Control of Blackwater m Coal Preparation DOE1
Plant Recycle and Discharge (IAG-D5-E685)
Stabilization of Coal Preparation Waste DOE*
Sludges (IAG-D5-E685)
LASL Determine leachability of trace elements from
coal preparation wastes and evaluate pollution
control methods.
Pennsylvania State Characterize black water generated by coal
University preparation plants and assess potential con-
trol methods.
Dravo Lime Collect coal preparation plant sludges and
perform laboratory stabilization tests.
' — Department of Energy, Coal Preparation and Analysis Laboratory, Pittsburgh, Pennsylvania
v — Department of Energy, Office of Enviroment, Washington, D.C.
l - Department of Energy, Office of Energy Technology, Washington, D.C.
228
-------
TABLE 2
S02 emission standards for coal fired steam generators
Application
Sulfur Emission
Reduction Limits,
Percent Ib S02/106 Btu
Existing Boilers (SIP's)
Current NSPS for Steam Generators
Revised NSPS for Utility Boilers'*'
85.
0.2-8.0
1.2
1.2 Max.
0.2 or 0.5 Floor
NSPS for Industrial Boilers
Unknown
Unknown
(*) Values under consideration
(+) 85 percent minimum for 24 hour average
(J) A provision of the standard will permit a 75 percent minimum sulfur reduction and an exemption of the
1.2 Ib SC>2/106 Btu level 3 days per month. This provision is to allow for variations in fuel sulfur
levels and pollution control device performance.
TECHNOLOGY ASSESSMENT
AND DEVELOPMENT
A CONTROL TECHNIQUE
SPECIFIC GRAVITY
SEPARATION
Improved techniques for the preparation of fine coal are needed to enhance
sulfur removal and coal energy recovery. The primary objectives of the technology
assessment and development activities are to evaluate the potential cleanability of
U.S. coals and the performance and costs of commercial equipment which can be
used for the beneficiation of fine coal. The development of chemical coal cleaning
processes is supported, as is applied research necessary to characterize the basic
mechanisms which govern beneficiation processes.
Passage of the 1977 Clean Air Act Amendments provides new emphasis for the
assessment of coal cleaning as an SC>2 emission control technique. New regulatory
actions in response to this legislation will significantly change the conditions under
which coal cleaning can be used as a method of complying with SC>2 emission
standards. Studies are now in progress to assess the applicability of coal cleaning in
meeting S02 emission standards for:
• Existing boilers regulated under state implementation plans.
• Current federal NSPS for coal-fired steam generators.
• Revised NSPS for coal-fired utility boilers.
• NSPS to be promulgated for industrial boilers.
While preliminary in nature, the results of portions of these studies warrant
discussion.
Table 2 summarizes the S02 emission standards which are expected to be
applicable to coal-fired boilers by 1980. Important new considerations mandated by
the 1977 Clean Air Act Amendments are the requirements for use of best available
control technology and a percentage reduction in the regulated pollutant. Thus, the
revised utility boiler regulations and new federal standards for industrial boilers will
require a percentage sulfur reduction in addition to an emission limit.
An evaluation of USBM data (5) suggests that specific gravity separation
conditions now commonly used for coal de-ashing can remove 25 to 55 percent of
the pyrite from U.S. coals, using the best available technology (table 3). Moderate
reductions in the coal top size and specific gravity of separation to conditions
corresponding to best current technology would provide pyritic sulfur reductions
ranging from 40 to 80 percent. Assuming that all the coal sulfur were converted to
SC>2 upon combustion, burning of these coals would result in SC>2 emission levels
ranging from 0.9 to 4.4 Ib S02/106 Btu. Although an increased reduction of pyritic
sulfur can be achieved at these lower particle sizes and specific gravity of separation,
coal carbon or Btu losses would increase to unacceptably high levels unless:
229
-------
TABLE 3
Coal desulfurization potential by coal cleaning*
Uncleaned Coal
Physical Coal
Cleaning (PCC)
Chemical Coal
Cleaning (CCC)
Average Pyritic
Sulfur Removed,
percent
-
43 80
95
Average Organic
Sulfur Removed,
percent
-
-
25
Average Reduction
in Ib SO2/106 Btu,
percent
-
16 55
48 73
Average Emission
Factor,
Ib S02/106 Btu
1.1 9.0
0.9 4.4
0.6 2.5
Based on Data from U.S. Bureau of Mines Rl 8118 for Averages for Each of
Six Coal Regions Assuming Application of Best Available Technology
I-
2
LLJ
O
cr
LLJ
Q_
O
o
LU
O
O
O
LL
O
H
o
O
CD
or
LLJ
100
ENERGY CONTENT OF
RECOVERABLE RESERVES:
1728 X 1015 Btu
TREATMENT METHOD
RAW COAL
PCC 1-1/2 INCH, 1.6 SPECIFIC GRAVITY
PCC 3/8 INCH, 1.6 OR 1.3 SPECIFIC GRAV.
MEYERS PROCESS
0.95 PYRITE S, 0.20 ORG. S REMOVED
— —-'BEST' FOR RESERVE
I
2.0
3.0
4.0
5.0
6.0
7.0
8.0
COAL SULFUR EMISSION ON COMBUSTION, Ib SO2/10b Btu
FIGURE •\-Estimated cleaning potential of northern Appalachian coals
• The sink or high specific gravity fractions were upgraded (desulfurized) by
further processing. Probable operations would include pulverization, specific
gravity separation, froth flotation, oil agglomeration, or chemical cleaning.
• The preparation plant was to produce multiple product streams to be used
in different boilers.
• High sulfur coals could be used in boilers with FGD or in boilers subject to
less stringent SO2 emissions regulations.
If experiments by Min and Wheelock on Iowa coals are applicable to other
U.S. coals, the best combination of physical cleaning techniques is potentially
capable of removing up to 90 percent of the pyrite sulfur (5). Combustion of coals
cleaned to these levels would produce emissions ranging from 0.8 to 3.5 Ib 502/10^
Btu.
230
-------
SULFUR CONTENT
AND REMOVAL VARY
Chemical coal cleaning processes can remove 95 to 99 percent of the pyritic
sulfur and 25 to 40 percent of the organic sulfur. Removal of 95 percent of the
pyritic sulfur and 25 percent of the organic sulfur from U.S. coals would result in
total sulfur reductions in the range of 53 to 77 percent (4).
The sulfur content and sulfur removal potential of coal by physical and
chemical techniques vary between coal regions and between coal beds in the same
region (6). Figure 1 presents the estimated energy content of the recoverable
Northern Appalachian coal reserves which can be cleaned to meet various S02
emission levels. Less than 5 percent of the raw coal is capable of meeting a standard
of 1.0 Ib S02/106 Btu. Crushing to 3/8 inch and physically cleaning at 1.6 or 1.3
specific gravity would increase the relative energy content of coals available for a
1.0 Ib SC>2/10" Btu emission standard to more than 20 percent. Chemical cleaning
of appropriate coals using processes capable of removing 95 percent of the pyritic
sulfur and 20 percent of the organic sulfur would provide more than 620 x
Btu (36 percent of total), capable of meeting a 1.0 Ib SO2/10^ Btu standard.
100
EC
LU
Q.
c/ 80
O
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LU
z 60
Q-
5
O
40
h-
20
O
O
C3
cr
LU
TREATMENT METHOD
RAW COAL
PCC 3/8 INCH, 1.3 SPECIFIC GRAVITY
0.95 PYRITE S, 0.40 ORG. S REMOVED
'BEST' FOR RESERVES
ENERGY CONTENT OF
RECOVERABLE RESERVES:
8834 X 1015 Btu
0.0
2.0
4.0
6.0
COAL SULFUR EMISSION ON COMBUSTION, Ib S02/10b Btu
FIGURE 2—Estimated cleaning potential of United States coals
HIGHER FEDERAL STANDARDS
Figure 2 presents similar data on the cleaning potential of U.S. coals. While
figures 1 and 2 indicate that physical and chemical coal cleaning can be used to
provide coals capable of meeting a variety of emission limits, new federal standards
requiring sulfur reductions above about 50 percent would preclude the use of
physical cleaning as a sole method of complying with SO2 emission standards in the
boilers where applicable. Sulfur reduction requirements of 80 percent or greater
would eliminate the use of chemical coal cleaning as an effective technology for
compliance with these standards.
The demand for physical or chemical coal cleaning will depend upon the
relative amounts of coals capable of meeting various sulfur emission standards and
the relative costs of other SO2 emission control techniques. In 1975, approximately
467 million tons of coal were consumed, primarily in utility, industrial, and
commercial boilers (7). Under the National Energy Plan (NEP), coal consumption for
these uses and non-boiler industrial applications is expected to exceed 1057 million
tons in 1985.
231
-------
1985 COAL CONSUMPTION
In 1975, virtually all coal firing was subject only to state emission regulations
for existing boilers. Table 4 presents estimates of the 1985 coal consumption by
boiler category and the emissions levels with which each boiler category must
comply. Even considering that few coals could be desulfurized to levels below 1.2
Ibs SO2/106 Btu, physically cleaned coals (if a high sulfur removal is not required)
could provide complying fuels to meet 79 percent of the projected steam-coal
demand in 1985. These projections are, of course, highly dependent upon impending
energy legislation and new emission standards to be promulgated by EPA.
Pollution control cost comparisons are complex. Factors unique to a given
application and site often determine which pollution control option is the most cost
effective. Simplified cost comparisons can be made by evaluating the ranges of
annualized costs for coal cleaning and FGD.
TABLE 4
Estimated coal energy consumption by emission regulation (million tons)*
Boiler Category
Utility(t) (§)
Industrial and
Commercial^' <§'
1975
404
63
Projected
<1.2
204 <*>
14
1985 Consumption
1.2 to <2.0
403
203
by Emission
2.0 to <4.0
113
52
Interval (Ib
<4.0
59
9
S02/106BTU)
Total
779
278
Total
467
218
606
165
68
1057
(*) Total 1985 consumption corresponding to NEP.
(t) One-third of all new utility boilers constructed after 1975 are assumed to comply with revised NSPS
of 0.5 to 0.8 Ib S02/1o6Btu. Two-thirds of all new utility boilers constructed after 1975 are
assumed to comply with current NSPS of 1.2 Ib S02/1Q6Btu.
(J) All new industrial and commercial boilers are assumed to comply with emission standards of 1.5 to 2.0
Ib S02/106Btu.
(§) The distribution of use for all categories of existing boilers is assumed to comply as follows:
<1.2 Ib S02/1Q6Btu, 20 percent; 1.2 to <2.0 Ib S02/106Btu, 35 percent; 2.0 to <4.0
Ib S02/106Btu, 30 percent; <4.0 Ib S02/106Btu, 15 percent.
D
CO
o
o
CO
0
CJ
_l
O
DC
h-
Z
O
o
g
CO
;>
LU
3.00
2.00
1.00
0.50
0.40
0.30
0,70
J i i ' ' I i i ' I | ' ' | ' • ' • i .
7 ccc ;
FGD
-
- PCC ' ".'
-
-J 1 1 . 1 , 1 , 1 1 . 1 , , , , 1 _
100 200 500 1,000 2,000 5,000
BOILER CAPACITY, 106 Btu/hr
FIGURE 3-Annualized SC>2 and paniculate control costs
10,000
232
-------
SULFUR REMOVAL
ABOVE 90 PERCENT
CONTROL COSTS
Utility and industrial FGD systems now in use have demonstrated sulfur
removal efficiencies in excess of 90 percent (8, 9, 10). FGD costs are sensitive to
the type of FGD system, boiler capacity, boiler capacity factor, and level of
desulfurization required. Annualized FGD costs increase with decreasing boiler
capacity, decreasing boiler capacity factor, and increasing sulfur removal.
Annualized coal-cleaning costs are sensitive to plant capacity, plant complexity,
and coal-replacement costs. Coal-replacement costs are defined as the cost of coal
energy which must be discarded with the plant residue (carbon and mineral matter).
Plant complexity increases with the number of different process operations involved.
Figure 3 presents estimates of annualized SC>2 and particulate control costs for
PCC, CCC, and FGD. (Particulate control costs of $0.10/106 Btu are included so
that the costs of coal cleaning can be compared with the costs of FGD which
contain costs for particulate control.) An analysis of the cost ranges in figure 3 and
the desulfurization potential of physical and chemical cleaning indicates that:
• Where technically feasible, cost savings from the use of PCC can be realized
for utility and industrial boilers, especially small boilers with low capacity
factors.
• PCC probably cannot be used to meet revised NSPS standards for utility
boilers, unless it is used in combination with FGD.
• Chemical coal cleaning does not appear to be cost competitive with FGD in
large base-loaded utility boilers. Chemical coal cleaning can possibly be used
in a cost effective manner in small industrial boilers with low capacity
factors.
• The most probable use of chemical coal cleaning is in combination with
PCC to provide lower sulfur levels than available from PCC.
CRUSHING AND GRAVIMETRIC
SEPARATION
SULFUR REDUCTION
POTENTIAL
In some cases, under current state and federal standards, the SC>2 control costs
from using FGD in combination with PCC may be less than those for using FGD
alone (11). Studies comparing the costs of a combination of PCC and FGD with
those of FGD in meeting an 80 to 90 percent sulfur removal standard have not
been completed.
The DOE Coal Preparation and Analysis Group at Bruceton, Pennsylvania, is
continuing laboratory experiments to determine the effect of crushing and
gravimetric separation on the liberation and removal of pyritic sulfur from U.S.
coals. These coals are collected from the principal coal beds of the United States.
Information generated from this study is necessary to assess the impact that physical
coal cleaning might have on the level of S02 emissions from stationary combustion
sources.
In 1976, a report of investigations was published on the sulfur reduction
potential of 455 coal samples from 6 major U.S. coal regions (6). Since then, an
additional 220 samples have been collected from the Western and Appalachian
Region States. During the past year washability analyses were completed on 31 raw
coal channel samples collected from Maryland, Ohio, and Pennsylvania. In addition,
four Arkansas and seven Texas lignite samples were collected and tested.
The data show that, on the average, the lignite samples contained 15.9 percent
ash, 0.23 percent pyritic sulfur, and 1.09 percent total sulfur on a moisture-free
basis. The average moisture content was 30.9 percent and the average heating value
was 10,377 Btu/lb. Only the two Arkansas samples, which contained less than 0.7
percent organic sulfur, could be upgraded to meet the current new source
performance standard of 1.2 Ib S02/106 Btu. All but one of the Texas lignite
samples contained more than 1 percent total sulfur; however, since most of this was
organic sulfur, none of the Texas samples could be upgraded to meet current NSPS.
233
-------
TECHNOLOGY ASSESSMENT
FINE COAL
HOMER CITY
COAL CLEANING
A major 3-year project to assess technology for the physical and chemical
desulfurization of coal was begun in January 1977. This project is being conducted
by Versar, Inc, with the assistance of the Denver Equipment Division of the Joy
Manufacturing Company. The principal activity on the project is the development of
data on the performance of commercial coal cleaning equipment in separating fine
coal and pyrite. Other project activities will include an evaluation of fine coal
dewatering and drying, chemical coal cleaning processes, coal preparation require-
ments for synthetic fuel conversion processes, and pollution control technology used
for coal cleaning.
Performance and cost data relating to the beneficiation of fine coal in
commercial equipment has been assembled. Insufficient fine coal performance data
were found to exist for dense media cyclones, hydrocyclones, and flotation cells. A
mobile laboratory has been constructed and is undergoing shakedown tests at a coal
preparation plant. Tests are planned at a number of commercial plants to obtain
additional performance data on fine coal cleaning.
An evaluation study of current chemical coal cleaning processes has been
completed (2). Reviews were conducted of 31 different processes; of these, 11 of
the most promising were selected for comparative evaluations. Estimated annual
operating costs for the 11 processes, including the cost of coal ($25/ton), ranged
from $38.50 to $65.72/ton. A process information summary of the 11 chemical coal
cleaning processes evaluated is presented in table 5.
Literature studies on coal drying, fine coal dewatering, and coal pre-preparation
requirements for synthetic fuel conversion processes are nearing completion.
An advanced coal cleaning pilot plant is currently under construction near the
Homer City Generating Station Power Complex, Homer City, Pennsylvania (figure 4).
TABLE 5
Process information summary of major chemical coal cleaning processes
Process &
Sponsor
"Magnex,"
Hazen Research
Inc., Golden
Colorado
"Syracuse"
Syracuse
Research Corp.,
Syracuse, N.Y.
"Meyers," TRW,
Inc., Redondo
Beach, Ca.
"LOL" Kennecott
Copper Co.
Ledgemont, Ma.
"ERDA" (PERC)
Bruceton, Pa.
Method
Dry pulverized coal
treated with Fe
(C0)5 causes pyrite
to become magnetic.
Magnetic materials
removed magnetically
Coal is comminuted
by exposure to NHg
vapor; conventional
physical cleaning
separates coal/ash
Oxidative leaching
using Fe2 (SC^) 3 +
oxygen in water
Oxidative leaching
using 02 and water
& moderate temp.
and pressure
Air oxidation &
water leaching @
high temperature
and pressure
Type Sulfur
Removed
Up to 90%
Pyritic
50-70%
Pyritic
90-95%
Pyritic
90-95%
Pyritic
95% Pyritic;
up to 40%
Organic
Stage of
Development
Bench & 91 kg/day
(200 Ib/day) pilot
plant operated
Bench scale
8 metric ton/day
for reaction
system. Lab or
bench scale for
other process
steps.
Bench scale
Bench scale 1 1 kg/
day (25 Ib/day)
continuous unit
under construction
Problems
Disposal of S-containing
solid residues, continuous
recycle of CO to produce
Fe (COg) requires
demonstration
Disposal of sulfur
containing residues
Disposal of acidic
FeS04 & CaSO; sulfur
extraction step 4 requires
demonstration
Disposal of gypsum
sludge, acid corrosion
of reactors
Gypsum sludge disposal;
acid corrosion at
high temperatures
Annual Operating
Cost $/Mg Clean
Coal ($/ton)
including Cost
of Coal <*>
44.8
(40.7)
43.4
(39.5)
47.9
(43.4)
50.6
(45.3)
56.9
(51.6)
Raw coal cost is included at $27.6/metric ton ($25/ton)
continued on page 236
234
-------
FIGURE 4—Back view of coal-cleaning pilot plant (Homer City), showing both slurry tanks
235
-------
TABLE 5 (continued)
Process
and
Sponsor
"GE" General
Electric Co.,
Valley Forge,
Pa.
"Battelle"
Battelle Memorial
Institute
Columbus, Oh.
"JPL" Jet
Propulsion
Laboratory
Pasadena, Ca.
"IGT" Insti-
tute of Gas
Technology hy
Chicago, II.
"KVB" KVB,
Inc. Tustin,
Cal.
"ARCO" Atlan-
tic Richfield
Company
Harvey, II.
(*) Raw coal cost
Method
Microwave treatment
of coal permeated
with NaOH solution
converts sulfur
forms to soluble
sulfides
Mixed alkali
leaching
Chlorinolysis in
organic solvent
Oxidative pretreat-
ment followed by
hydrodesulfurization
at 800°C
Sulfur is oxidized
in N02-containing
atmosphere, sulfates
are washed out
Not given
Type Sulfur Stage of
Removed Development
75% Total S Bench scale
95% Pyritic; 9 kg/hr (20 Ib/
25-50% hr) mini pilot
Organic p|ant and bench
scale
90% Pyritic; up Lab scale but
to 70% Organic proceeding to
bench and mini
pilot plant
95% Pyritic; Lab and bench
up tp 85%
Organic
95% Pyritic; to Laboratory
40% Organic
95% Pyritic; Continuous 0.45
some Organic kg/hr (1 Ib/hr)
bench scale unit
Problems
Process conditions
not established.
Caustic regeneration
process not established
Closed loop regeneration
process unproven.
Residual sodium in
coal
Enviromental problems;
conversion of HCI to
CL not established
Low Btu yield (55%).
Change of coal matrix
Waste & possibly heavy
metals disposal. Possible
explosion hazard via dry
oxidation
Unknown
Annual Operating
Cost $/Mg Clean
Coal ($/ton)
including Cost
of Coal '*'
44.3
(40.2)
62.0
(56.1)
50.3
(45.9)
72.4
(65.7)
53.8
(48.8)
51-64
(46-58)
Estimated
is included at $27.6/metric ton ($25/ton).
TABLE 6
Homer City plant product specifications
Medium-sulfur Low-sulfur
Coal Coal Refuse
Weight distribution, percent
Energy distribution, percent
Energy content, Btu/lb (dry
Ash content, percent
Sulfur content, percent
Emission factor, Ib S02/106
56.2 24.7 ' 19.1
61.6 32.9 5.5
basis) 12,549 15,200 3,367
17.75 2.84 69.69
2.24 0.88 6.15
Btu 3.57 1.16 36.54
* Overall plant Btu recovery is 94.5 percent which includes 1
credit for thermal drying loss.
TABLE 7
Phase 1 plant acceptance test results (moisture-free basis)
Ash
%
Total Btu
Sulfur, % %
percent
Ib S02/106
Btu
Feed coal 20.05 2.33 12,239 3.82
Clean coal 13.05 1.51 13,527 2.24
Refuse 76.85 5.37 2,646 40.81
Average Btu recovery, percent — 97.80
Average yield, percent — 85.50
Average sulfur removal, percent - 41.36 (Ib SC>2/106 Btu Basis)
236
-------
UNIQUE DESIGN FEATURES
3-YEAR PROJECT
AT HOMER CITY
The coal preparation facility is jointly owned by Pennsylvania Electric Company (a
subsidiary of General Public Utilities Corporation) and New York State Electric and
Gas Corporation. The facility will process 5.2 million tons of ROM coal per year,
with a design capability of 1,200 tons per hour. The plant has four distinct process
circuits: 1) coarse coal, 2) medium coal, 3) fine coal, and 4) fine coal scavaging.
Unique design features of the Homer City plant include:
• Selective crushing to maximize the amount of 1/4 inch by 100 mesh coal.
• Use of small diameter (14 inches) heavy media cyclones to process the 9 x
100 mesh size fractions.
• Computerized control of the dense media at a low specific gravity (1.3).
The major purpose of the plant is to clean coals for compliance with SO2
sulfur emission standards. As shown in table 6, the plant is expected to produce
medium and low sulfur coals. The medium sulfur coal will be used in the two
existing 600 MW generating units to meet a Pennsylvania emission standard of 4.0 Ib
SC>2/106 Btu. The low sulfur coal will be used in a new 650 MW unit to meet
Federal NSPS of 1.2 Ib S02/106 Btu.
EPA, PENELEC, EPRI, and DOE are cooperatively supporting a 3-year test
project at the Homer City complex. Objectives of the project are to:
• Determine the variability of sulfur and other pollutants in coal fed to the
cleaning plant.
• Determine the performance of equipment used for the separation of coal
and pyrite.
• Determine the capability of plant process controls to maintain the coal
product streams within sulfur, ash, and Btu specifications.
• Characterize pollutant streams emitted from the preparation and power
plants.
• Determine if a need exists for the development of improved pollution
control technology.
• Evaluate the effects of using clean coal on the performance of the boilers
and electrostatic precipitators at the power plant.
• Evaluate the effectiveness of planned residue disposal techniques.
• Determine the fate of potentially hazardous minor and trace pollutants
contained within the coal used at the preparation and power plants.
• Determine capital and operating costs of the preparation and power plants;
i.e., the costs of using, physical coal cleaning to meet SO2 emission
standards.
ACCEPTANCE TESTS
The preparation plant is scheduled for construction in two phases. The phase 1
plant, completed in October 1977 was capable of cleaning coal to 4.0 Ib 502/10^
Btu. The phase 1 plant, shut down during the United Mine Workers strike, was not
scheduled to begin operation until this spring in order to expedite construction of
the phase 2 plant-cleaning circuits. The complete plant is scheduled to begin
operations in the fall of 1978.
Acceptance tests on the phase 1 plant were completed last fall. Operation of
the equipment and plant was near design conditions. The average sulfur content of
the clean coal over the 3-day acceptance test period was 2.24 Ib S02/106 Btu.
Table 7 summarizes acceptance test results.
237
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DENSE MEDIA PILOT
PLANT
FROTH FLOTATION
COAL/PYRITE FLOTATION
ADSORPTION/DESORPTION
REACTIONS
A number of tests are now being conducted to establish electrostatic
precipitator and boiler performance characteristics while the power plant boilers are
burning uncleaned coal. Preparation plant performance tests and power plant
operating evaluations are scheduled to begin late this year.
A dense-media cyclone pilot plant test program is being conducted by DOE at
Bruceton, Pennsylvania. This project is being conducted with the support and
cooperation of the owners of the Homer City power complex, EPA, and the Electric
Power Research Institute. The objective of the test program is to detail and
optimize the performance of dense-media cyclones for fine coal cleaning at lower
than normal specific gravities of separation. This program was initiated during the
past year. The cyclone pilot plant has been designed and constructed, and all
necessary equipment has been installed. Several shakedown tests were recently run to
check plant operation and to establish procedures for sample collection, processing,
and analysis. A 12-month test program is planned to evaluate the effects of several
variables on the performance of the dense media cyclone: media to coal ratio, inlet
pressure, orifice size, magnetite grade, media viscosity, media additives, and
magnetite size distribution. The results of these pilot plant tests are to be used to
evaluate the performance of the dense media circuits in the Homer City coal
cleaning plant.
Froth flotation is commercially used to separate coal and mineral matter.
Froth flotation is a physical/chemical process for the separation of solids, based
upon the selective adhesion of water to some particles and the selective adhesion of
air to other particles. Separation of coal from mineral matter occurs as finely
disseminated bubbles are dispersed throughout a coal-water slurry. The coal particles
in the slurry adhere to the air bubbles and are transported to the surface of the
pulp; i.e., the coal/air/water mixture. These bubbles and their attached coal particles,
commonly referred to as froth, are then removed as a froth overflow; the mineral
matter remains in suspension and is removed with the water underflow.
The process of bubble adhesion can be modified by the use of certain
chemical reagents. These reagents enhance the selective adhesion of air or water to
certain particles. Reagents are also used to stabilize the froth, thus allowing time for
removal of the floated particles. Unfortunately, the surface properties of some coal
and pyrite particles are not sufficiently dissimilar to permit efficient separation. In
some cases, multiple stages of flotation and the proper combinations of reagents
result in a separation (12, 13). In other cases, the coal does not appear to be
amenable to coal/pyrite separation by flotation. The DOE coal/pyrite flotation
process, developed specifically for coal/pyrite separation, consists of a first stage coal
flotation step to remove coarse, free pyrite and other refuse. The clean coal froth
concentrate is then repulped and treated with a coal depressant, a pyrite collector,
and a frother to selectively float the remaining pyrite in the second state.
The installation of a two-stage coal/pyrite flotation circuit in the Lancashire
No. 25 preparation plant under a cooperative agreement between Barnes and Tucker
Company and the DOE was completed in late September 1977. A 1-year test
program was started after termination of the UMW strike.
A study of adsorption/desorption reactions in the desulfurization of coal by
the DOE two-stage flotation process (12) has been completed by the University of
Utah (14). This research has provided information concerning the method of
adsorption of various organic depressants on coal. It has shown that this adsorption
is physical rather than chemical, and the depressant cannot be removed by repeated
washing.
Laboratory flotation tests demonstrated that the first stage coal flotation
response is sensitive to the residual concentration of the second stage coal depressant
(Aero Depressant 633) in the recycled water. However, it was shown that repeated
contact with fresh coal removes much of the residual depressant from the water,
suggesting that the contact of recirculated water with fresh coal and refuse in a
preparation plant might remove most of the residual depressant.
238
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HIGH-GRADIENT
MAGNETIC SEPARATION
The other portion of this research concerning the second stage pyrite collector
(potassium amyl xanthate) indicated that the adsorption of xanthate by pyrite
involves a chemisorption reaction which, in essence, goes to completion. Also, it was
found that coal/pyrite flotation response with amyl xanthate differs significantly
from that of ore/pyrite. The pyrite collector consumption is about an order of
magnitude greater for coal/pyrite than for ore/pyrite. The reason for the high amyl
xanthate requirement for coal/pyrite flotation appears to be related to surface
heterogeneities in the marcasite component of the coal/pyrite, particularly clay
inclusions, which contribute significantly to its hydrophilic character.
High-gradient magnetic separation (HGMS) is a new technique which provides a
practical means for separating small, weakly magnetic particles on a large scale. This
technology, utilized commercially in the purification of kaolin clay, was investigated
by General Electric Company with the objective of establishing the technical
feasibility for removing a substantial fraction of the inorganic sulfur from dry coal
powders.
(15):
As a result of tests to evaluate the feasibility of HGMS, it was concluded that
• Dry magnetic separation by HGMS is feasible if the coal fines are first
removed. Gravity feed techniques must be employed since the mixing
effects of pneumatic transported mixtures counteract the magnetic separa-
tion effects.
• Multiple passes may be desirable to increase coal recovery (only single
passes were made in this work).
• Pyrite removal by HGMS from oxidized and freshly mined coals is
substantially the same.
DEWATERING OF COAL
USE OF SURFACTANTS
Fine coal handled or cleaned in slurry form is dewatered to render it suitable
for conveying and blending, to decrease its transportation cost, and to increase its
effective calorific value. The removal of water from coal finer than 28 mesh is
difficult and expensive. Vacuum filters are relatively economical for dewatering coal
in the minus 28 mesh size range, but the product usually contains over 20 percent
moisture. As a result, thermal drying is often required to reduce the moisture
content of the filter cake to acceptable levels. However, thermal driers are costly
and a source of air pollution.
Under a Department of Energy (DOE) contract, Syracuse University is studying
the use of surfactants to enhance the dewatering of fine coal (16). (Surfactants are
chemicals used to reduce the surface tension of water.) Previous research by DOE
has shown that the addition of surfactants to coal slurries prior to vacuum filtration
can reduce the final moisture content of the dried coal filter cake. Results of the
Syracuse investigation indicate that surface tension is not a unique criterion for
predicting the dewatering behavior of surfactant solutions in the reduction in filter
cake moisture content. Changes in surface energies at the solid/liquid and solid/air
interfaces may also be important. Test data show, for example, that it takes the
adsorption of six layers of a non-ionic surfactant at a surface tension of 30.92
dynes per cm to slightly surpass the final water content of coal achieved with the
adsorption of a monolayer of an anionic surfactant at a surface tension of 40.66
dynes per cm. Test data also seem to indicate that excessive quantities of surfactants
may result in the formation of micelles (organic molecular aggregates) which entrap
water and adhere to the surface of coal particles. This would result in increased
water retention in the filter cake.
The successful use of surfactants as dewatering promoters in coal preparation
plants will therefore depend on the careful control of surfactant concentration in
the vacuum filter feed.
239
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FIGURE 5—Reactor test unit at Capistrano, California
H2 S04
t Fe2 (S04)3
Ca 0
COAL
REACTOR
nj
REACTOR CONDITIONS
TEMPERATURE: 230-270°F
PRESSURE: 30-80 PSIG
RESIDENCE TIME: 5-8 HRS
PARTICLE SIZE: 14 MESH
COAL
FIGURE ^-Meyers chemical coal cleaning process
240
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AQUEOUS FERRIC
SALT LEACHING
MEYERS CHEMICAL
COAL CLEANING
LEACH SOLUTION
GRAVITY SEPARATION
In previous years EPA supported bench and laboratory scale development work
on coal desulfurization by aqueous ferric salt leaching (17, 18). This process
developed by TRW is capable of removing 90 to 95 percent of the pyritic sulfur
from U.S. coals. Construction of a 1/3-ton per hour reactor test unit (RTU) capable
of pilot scale testing has been completed at Capistrano, California. More than 254
hours of RTU test operations have been completed and 49,700 Ibs of coal have been
processed. Figure 5 is a picture of the Reactor Test Unit (RTU).
The test reactor was shut down in February 1978 because of metal corrosion
in the primary reactor. Replacement of the reactor vessel and resumption of testing
depend on a possible transfer of the project to DOE. Meanwhile, bench scale tests
are continuing to evaluate a process modification called Gravichem.
Figure 6 is a schematic of the Meyers chemical coal cleaning process. Coal is
mixed with an aqueous solution of ferric sulfate, previously derived from the coal,
to form a slurry. The slurry temperature is raised to 100°-130°C where the ferric
sulfate oxidizes the pyritic sulfur content of the coal to form elemental sulfur and
iron sulfate. At the same time, oxygen or air is introduced to regenerate the reacted
ferric sulfate. Iron sulfate dissolves into the leach solution while the elemental sulfur
is removed in a second extraction. The coal is dried and solvent recovered. The
products of the process are iron sulfate, which may be limed to give a dry gypsum
and iron oxide material, and elemental sulfur. Trace elements from the coal are
rejected from the leach solution with the stabilized gypsum/iron oxide solid.
Elemental sulfur is the most desirable product which can be obtained in the process
of controlling 862 pollution since it may be easily stored without additional
pollution or may be marketed. The gypsum/iron oxide product is a storable solid
product.
The RTU incorporates equipment to evaluate the key process steps of
coal/leach solution slurry formation, coal leaching, leachant regeneration, and
coal/leachant filtration (separation). Checkout and shakedown of the RTU was
completed at the end of September 1977. Initial performance tests were made on
Appalachian coal donated by the American Electric Power Service Corporation
(AEP) from its Martinka mine. Operation of the plant through January of 1978
demonstrated that the RTU could be run continuously in three-shift operations. The
input coal, containing 1 percent inorganic sulfur, was continuously and reliably
reduced to a pyritic sulfur level of 0.16 percent (19). Although there was no
measurable coal loss, calculations indicate an overall process energy efficiency of 93
to 96 percent, including process heat and electrical energy requirements. The average
heating value of the processed coal was increased by 350 Btu/lb, RTU coal product,
after bench-scale extraction of residual sulfate and elemental sulfur, was reduced to
a total sulfur content of 0.68-0.75 percent (1.0-1.2 Ib S02/106 Btu).
Leach rates in the RTU were improved over bench-scale values by an average
factor of 5 due mainly to favorable coal segregation in the primary reactor (19).
The leach solution/coal/oxygen environment caused corrosion in the primary
reactor/regenerator system indicating that upgrading of the 316L material of
construction is needed to support further testing. Extensive evaluations using
erosion/corrosion coupons indicated that fiber reinforced plastics, elastomers, and
316L stainless steel are suitable for leach solution/coal service at temperatures up to
90°C. Titanium, Hastelloy, or rubber-lined brick over mild steel are needed for
reactor/regenerator service conditions at temperatures up to 130°C (19).
Supporting bench-scale experimentation showed that the iron sulfate/sulfuric
acid leach solution can be used as a homogeneous dense media to efficiently
gravity-separate fine coal at specific gravities of 1.2 to 1.35. Beneficial process cost
improvements are obtained, based on using this gravity-separation effect. A
significant portion of the input coal which floats in the leach solution is almost
pyrite free and may bypass the reactor, elemental sulfur extraction, and dryer
portions of the Meyers Process. This revised technology is termed the Gravichem
Process (figure 7). When applied, at bench-scale, to a Tennessee Valley Authority
(Interior Basin) coal containing 12 percent ash and 7 Ib of 502/10^ Btu, two
products are obtained: a 4-percent ash float coal containing 3 Ib S02/106 Btu and
241
-------
MICROWAVE DESULFURIZATION
an 11 to 12 percent ash sink coal containing 4 Ib S02/106 Btu after treatment by
the Meyers Process (19). Both of these products meet state SC>2 emission standards
for this coal.
Laboratory experiments by the General Electric Company have demonstrated
the technical feasibility of coal desulfurization by microwave energy (20). Pyrite is
preferentially excited by the microwave energy producing volatile or water soluble
sulfur compounds which may be easily removed from the coal. Also, microwave
irradiation of mixtures of coal, water, and NaOH appears to convert both pyritic
and organic sulfur to water soluble sulfides.
H2S04_*
Fe2(S04)3
SULFUR
FIGURE 7—Gravichem process
TREATMENT CONDITIONS
NOT SEVERE
BATTELLE HYDROTHERMAL
Treatment conditions are not severe. Exposure times of less than 1 minute at
atmospheric pressure are adequate. Pyrites and sodium hydroxide (with small
amounts of water) absorb microwave energy much more efficiently than coal itself.
It is postulated that sulfur reactions occur due to selective activation of FeS2<
NaOH, and H20. The action of these compounds produces localized high
temperature and high pressure conditions which accelerate sulfur reactions before the
coal reaches decomposition (volatilization) temperatures. Present cost estimates
suggest that microwave desulfurization may be economically competitive with other
chemical desulfurization processes. Laboratory experiments are continuing under
sponsorship of EPA and DOE.
Battelle's Hydrothermal process is capable of removing 95 percent of the
pyritic sulfur and up to 40 percent of the organic sulfur from a variety of U.S.
coals. A large fraction of the process costs result from unit operations which occur
after the reaction step converts the pyritic and organic sulfur to water soluble
sulfides. These unit operations include the separation of liquids and solids, the
regeneration of spent leachant, and the dewatering/drying of the product coal.
EPA-supported laboratory experiments to evaluate methods for reducing the
costs of these unit operations indicate that (21):
• Spent leachant and reacted coal should be separated under oxygen free
conditions to prevent oxidation of sodium sulfide to sodium sulfate. The
latter is water soluble and cannot be precipitated from the spent leachant in
subsequent steps.
242
-------
• Iron carbonate is probably the most cost effective reactant for regeneration
of the spent leachant.
• Serial washing and vacuum filtration to wash residual leachant from the
coal, followed by use of screen bowl centrifuges, appear to be the most
effective coal washing and dewatering procedure.
Battelle anticipates that incorporation of these process changes will reduce
costs to the range estimated for competitive chemical coal cleaning processes.
ENVIRONMENTAL ASSESSMENT
Overall objectives of the environmental assessment activities have been to
characterize coal contaminants and to identify the fate of these contaminants during
coal processing and coal use. Initial studies have focused on sulfur and potentially
hazardous accessory elements (minor and trace elements) contained in coal. Recent
studies have been concerned with a wider range of pollutants—those which may be
considered hazardous or toxic under the provisions of the Water Pollution Control
Act (priority pollutants), the Resource Conservation and Recovery Act (hazardous
wastes), the 1977 Clean Air Act Amendments (hazardous air pollutants), or the
Toxic Substance Control Act. The basic intent of the environmental assessment
activities is to identify pollutants which pose health or ecological threats and devise
cost effective strategies for dealing with the pollutants.
A 3-year project to assess the environmental impacts of coal preparation, coal
transportation, and coal storage is being conducted for IERL-RTP by Battelle's
Columbus Laboratories. Major project activities are to include:
• The development of a technology overview containing a description of all
current coal cleaning processes and their associated pollution control
problems.
• The development and performance of an environmental test program to
obtain improved data on pollutants from commercial coal cleaning plants.
• The development of criteria to be used in assessing the potential health and
ecological impacts of pollutants from coal cleaning processes.
• The performance of studies to determine the relative environmental impacts
of coal cleaning, FGD, and other SC>2 emission control methods.
PHYSICAL AND CHEMICAL
TOXICITY CHARACTERIZED
MATE, EPC, AND EOD
DEFINED
Studies to develop criteria for assessing the relative environmental hazards
associated with pollutants resulting from coal preparation, coal transportation, and
coal storage are nearing completion. The approach has been to characterize the
physical and chemical toxicity of pollutant or effluent streams sampted at their
respective sources. This differs from the approach taken in environmental impact
assessments—the characterization of air, water, and biological quality in the facility
under study. The source assessment criteria incorporates methodologies being
developed by IERL-RTP and adapts them to coal cleaning processes (22).
The fundamental criterion for evaluating the importance of any pollutant is
the relationship between its concentration and the maximum concentration which
presents no hazard to man or environmental biota. In evaluating the relative hazard
of various pollutant concentrations, it is convenient to define three important
concentration levels: Minimum Acute Toxicity Effluents (MATEs), Estimated
Permissible Concentrations (EPCs), and Elimination of Discharge (EOD).
MATE is defined as that pollutant concentration in undiluted emission streams
that would not adversely affect those persons or ecological systems that are exposed
to the streams for short periods of time. EPCs are concentration levels of dispersed
emission streams which will not cause the receiving medium (air or water) to exceed
safe continuous exposure concentrations. EOD is defined as that concentration of
pollutants in emission streams which will not cause a pollutant concentration to
exceed natural background levels.
243
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Using these concepts and existing health and ecological effects data,
Multimedia Environmental Goals (MEG's) have been developed to aid in assessing the
degree of hazard associated with pollutants in energy process emission streams.
COAL PREPARATION
POLLUTANT LIST
Existing health and effects data have been used to generate MEG's for
approximately 650 known pollutants associated with energy processes (23). Using
this information and existing data on coal contaminants, pollutants from coal
preparation, and pollution from coal waste disposal, a list of about 75 priority coal
preparation pollutants has been selected (24). This list includes 49 elements and 23
chemical substances or aggregated pollutant parameters. A shorter abbreviated list of
pollutants, being used to evaluate chemical and physical transport models as well as
estimated emissions and permissible concentrations, includes arsenic, beryllium,
cadmium, iron, mercury, lead, manganese, selenium, sulfate sulfur, sulfur dioxide,
nitrate nitrogen, and nitrogen oxides.
COAL CLEANING
TEST SITES
MASTER TEST PLAN
HUMAN HEALTH
EFFECTS ASSAYS
Concurrent with the development of source assessment criteria, studies are in
progress to select coal cleaning plant sites for environmental testing. The
classification of coal cleaning facilities into various site categories has been based on
four criteria: the acid neutralization potential of the soil surrounding the facility,
the pyritic sulfur content of the run-of-mine coal, the average annual precipitation,
and the coal cleaning process technology. By taking combinations of the extremes
(high and low) for each variable and eliminating combinations which do not occur,
10 possible site categories were obtained.
An initial sorting of the more than 400 known coal cleaning plants, using
information available in the literature, produced lists of facilities which correspond
to each of the 10 site categories. For categories which included a large number of
cleaning plants, three secondary constraints were imposed that eliminated plants
considered undesirable because of field sampling problems. This shortened list
includes 46 facilities. Site visits are planned to those listed facilities to obtain
information which, although not available in the literature, will be required before
final selection of sampling sites.
The master test plan is being developed to ensure a comprehensive test
program and to facilitate the planning and preparation of the site-specific field test
plans at the coal cleaning facilities designated as test sites. The master test plan will
identify the potential pollution sources associated with a generalized coal cleaning
plant and will suggest the media likely to be impacted by the effluents from these
sources. Test objectives related to each pollution source will be defined to simplify
the process of selecting sampling locations and measurements that are critical to
those objectives. The phased approach to environmental testing under development
by IERL-RTP is also presented.
The common elements relating to water and air quality parameters to be
measured at each test site are:
• Process wastewater sampling-upstream and downstream from pollution
control devices.
Surface runoff and leachate sampling.
Ground water sampling.
ROM and final product coal sampling.
Refuse disposal sampling.
Air pollution emissions from thermal dryers, coal piles, and the refuse
disposal area.
Included in the common element portion of the master test plan is a general
discussion of the importance of performing ecological and human health effects
assays and a short description of tests that should be performed on each type of
sample. This test plan is now undergoing final revision.
Between December 1976 and April 1977, a series of environmental tests were
conducted at the Homer City Generating Station near Homer City, Pennsylvania.
The intent of this monitoring was to evaluate the air, water, and biological quality
244
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COAL CONTAMINANTS
ORGANIC AFFINITIES
CONCLUSION FROM FREEPORT
SEAM
TRACE ELEMENTS
in the vicinity of an advanced coal cleaning plant which was then under
construction. These studies were conducted prior to operation of the cleaning plant
as a reference point for furture, and more comprehensive, environmental testing
planned during operation of the plant. The results of these tests are currently being
evaluated.
Three distinct programs are directed to the identification and characterization
of contaminants in coal. Specifically, the research attempts to demonstrate the
occurrence, association, and distribution of trace element and mineral phases in the
coal seam.
One portion of this research, led by the Illinois State Geological Survey,
concentrates on coals of the Illinois Basin, This work has three principal goals: 1) to
determine the mode of occurrence and distribution of trace elements and minerals in
coal seams; 2) to study the mineralogy and genesis of sulfide minerals in coal, and
3) to evaluate the potential for removal of minerals from coal by various
preparation techniques.
The most significant contribution recently was the publication of Trace
Elements in Coal: Occurrence and Distribution (1) which summarizes the results of
the last 6 years of EPA supported activity. The report succeeded in demonstrating
various levels of organic affinities for some of the trace elements in coals. Ge, Be,
B, and Sb all have high affinities for organic matter, with Ge being highest. Zn, Cd,
Mn, As, Mo, and Fe have a tendency to reside with the inorganics, with Zn and As
being most consistent. Elements including Co, Ni, Cu, Cr and Se have intermediate
organic affinities, suggesting that these metals are present in coals as organometallic
compounds, chelated species, or as adsorbed cations.
A second area of investigation by the U.S. Geological Survey is underway in
Reston, Virginia. This project has dual objectives. One is to determine the geologic
factors which affect or control the physical cleanability of coal and to develop
geologic models which can be used to help maximize efficiency and minimize
environmental impact from coal mining, cleaning, and burning. The second objective
is to provide the necessary chemical, physical and mineralogical data on the Nation's
coal resources to permit evaluation of the environmental impact resulting from coal
preparation and utilization.
The annual report for the first objective of this study is nearing completion;
however, several preliminary conclusions can be drawn on the Upper Freeport coal
seam which the report will address. Despite the complex nature of this seam,
stratigraphic analysis suggests that facies (geologic zones) in the coal can be mapped
throughout the study area. Therefore, those aspects of coal quality which are a
function of facies can also be mapped. Mineralogic determinations suggest that
quartz, pyrite, kaolinite, illite, and calcite are the most abundant species with
marcasite, siderite, sphalerite, and chalcopyrite occurring occasionally. Data on trace
elements of environmental concern suggest that arsenic is associated with the iron
disulfides, cadmium appears with zinc in sphalerite, and selenium is associated with
lead as a lead selenide.
The third study in this area, being conducted at the Los Alamos Scientific
Laboratory (LASL), deals with the evaluation of the contaminant potential of coal
preparation wastes. The research has three distinct phases: 1) to characterize the
minerals, trace elements, and their association in coal preparation wastes, 2) to study
the effects of weathering and leaching on trace elements in coal wastes, and 3) to
identify and evaluate techniques for controlling or preventing trace element
contamination from coal waste materials. Phases 1 and 2 have been completed. The
results are available in two EPA publications (3,25). A second annual progress report
is in preparation. The results of the LASL work are discussed later in this paper in
relation to Pollution Control Technology.
DOE recently completed a study showing the trace element content of various
coal specific gravity fractions for 10 U.S. coals (26). Most of the trace elements of
interest were concentrated in the heavier specific gravity fractions of the coal,
indicating that they are associated with mineral matter. Removal of the high density
245
-------
10'
CO
g
O in'
CO IU
Q
LU
O
CO
CO
<
O
,0-
10'
,-2.
<
QC
O
LLI
tr
^^ INTERMIXED
LAYERED
AT OUTLET
NO CONTROL
00
2.5
5.0
T
I
7.5 10.0 12.5
VOLUME (LITERS)
15.0
17.5 20.0.
TOTAL DISSOLVED SOLIDS VS LEACHATE VOLUME FOR COLUMN LEACH-
ING STUDY OF COARSE LIMESTONE/REFUSE MIXTURES (-3/8 in).
FIGURE 8-Control of trace element leaching
FATE OF COAL
TRACE ELEMENTS
POLLUTION CONTROL
TECHNOLOGY
fractions of coal should result in trace element reductions, ranging (for some
elements) up to 88 percent.
In a related, but greatly expanded effort, the Bituminous Coal Research Inc. is
evaluating the fate of coal trace elements during mining, transportation and
preparation. These studies encompass the collection and analysis of 20 run-of-the-
mine (ROM) samples which are representative of U.S. coals. To date, two 1,000
pound run-of-mine samples have been collected. The first was a blend of Upper and
Lower Freeport bed coals from the Rochester & Pittsburgh Coal Company, Indiana,
Pennsylvania. The second was Illinois No. 6 bed coal from the Old Ben Coal
Company, Benton, Illinois. Each sample was crushed and divided into three size
fractions: 1-1/4 inch x 1/4 inch, 1/4 inch 30 mesh, and 30 mesh x 0. Each size
fraction was subdivided into three specific gravity fractions (1.34, 1.55, and 1.80).
Each size and specific gravity fraction has been analyzed for As, Be, Cd, Cr, Cu, F,
Pb, Mn, Hg, Ni, Se, V, and Zn. Analyses are now being performed to determine the
relative organic or inorganic affinity of each element.
The subprogram to develop coal cleaning pollution control is in a formative
phase. A wide variety of techniques exist for controlling conventional pollutants
(total suspended solids, total paniculate emissions, pH,). However, as coal cleaning
processes evolve and as pollution control regulations become more specific and
stringent, modifications and improvements must be made in pollution control
techniques. The subprogram for development of pollution control technology,
therefore, addresses current and projected pollution control needs.
The Los Alamos Scientific Laboratory (LASL) is conducting studies to assess
the potential for environmental pollution from trace or minor elements that are
discharged or emitted from coal preparation wastes and stored coals, and to identify
suitable environmental control measures.
246
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STATIC AND DYNAMIC
TESTS
TOXIC ELEMENTS
CONTROL METHODS
ALKALINE NEUTRALIZATION
Initial studies were concerned with the assessment of the identities, structure,
and chemistry of the trace elements and minerals in samples of high sulfur, coal
preparation wastes (3). In accordance with this aim, extensive quantitative analyses
were made of the elemental and mineral compositions of more than 60 refuse
samples collected from three coal cleaning plants in the Illinois Basin (25). These
waste materials were found to be composed mainly of clay minerals (illite, kaolinite,
and mixed-layer varieties), pyrite, marcasite, and quartz. Smaller amounts of calcite
and gypsum were also identified in some of the refuse samples. The elements
present in greatest abundance (Si, Al, Fe, Na, K, Ca, and Mg) are components of
the major mineral species. Potentially toxic trace elements found in environmentally
significant quantities included Mn, Co, Ni, Cu, Zn, As, Cu, Se, Cd, and Pb.
The structural relationships and associations among the trace elements and
major minerals in the refuse samples were investigated by statistical correlation of
chemical and physical data and by direct observation of refuse structure with
electron and ion microprobes. It was found that the mineral associations of many of
the trace elements that have been identified as being highly leachable from the
refuse samples (and, therefore, of environmental concern) were associated with the
refuse clay fractions rather than the major pyritic fractions.
In studies completed this year, static and dynamic tests were conducted to
determine the trace element leachabilities of the various waste samples. Generally,
the trace elements leached in the highest quantities (Fe, Al, Ca, Mg, and Na) are
constituents of the major refuse minerals. Several other elements, while not present
in the refuse in large amounts, were nonetheless found to be easily removed by
leaching. This group included Co, Ni, Zn, Cd, and Mn. The highest degree of trace
element leachability was exhibited by waste samples that produced the most acidic
leachates. Trace element leaching was also found to be a function of refuse particle
size (relative surface area), temperature, and access to air.
Based on results of the mineralogy studies, elemental studies and the
laboratory leaching experiments, F, Al, Mn, Fe, Co, Ni, Cu, Zn, and Cd were
selected as the elements of most concern in the Illinois Basin preparation plant
wastes. These elements are often toxic in aqueous systems or soils or are present in
the refuse materials in a highly leachable state.
Following completion of the leaching studies, experiments were started to
assess potential technologies to (a) prevent the release (leaching) of trace elements
from coal preparation wastes, or (b) remove the dissolved trace elements from acidic
leachates.
Tests were conducted to evaluate the degree of trace element control that
could be exerted by adding neutralizing agents to high sulfur refuse materials prior
to disposal to reduce leachate acidity and trace element dissolution (27). Column
leaching experiments that utilized mixtures of crushed limestone and refuse were
conducted to test the effectiveness of this control method. Limestone was combined
with the refuse to simulate three different geometric arrangements in refuse dumps:
limestone placed on top of the refuse, limestone placed beneath the refuse, and
limestone intermixed with the refuse.
Adding coarse limestone to the acid refuse material was only partly successful
in controlling leachate acidity (27). The pH values of the leachates from most of
the refuse/limestone combinations were higher throughout the leaching tests than
were those for the refuse alone; however, even in the best instances, neutralization
by the in situ limestone was not sufficient to prevent the dissolution of refuse solids
(figure 8). As expected from the leaching studies, the release of some trace elements
was found to be dependent upon the degree of acidity control. Elements, such as
Al, K, V, and Cr (which were quite sensitive to leachate pH) tended to be released
in lesser quantities from the refuse limestone systems than from pure refuse. There
was little apparent effect of the limestone additions on the leachate concentrations
of Fe, Mn, Co, Cu, and Zn.
Other studies focused on potential control technologies to reduce the content
of undesirable trace elements extant in the aqueous drainages associated with refuse
247
-------
disposals. Tests were conducted to evaluate the degree to which trace element
solubilities are affected by treatment with neutralizing agents, such as lime,
limestone, and lye (sodium hydroxide). These experiments indicated that alkaline
neutralization is an effective means for controlling the trace element concentrations
in refuse waste water. The pH and iron contents of the treated solutions were
within acceptable limits, based on the 1977 EPA effluent limitation guidelines. Mn,
however, was a borderline case that sometimes exceeded acceptable concentration
limits in the leachates. Lye was generally more effective than limestone or lime in
reducing the trace element content of the drainage samples.
CONTROL OF BLACK WATER
Black water (process waste water) from coal preparation plants consists of
mixtures of fine coal, clay minerals, quartz, calcite, pyrite, and other mineral
particles dispersed in water. The effluents must be effectively treated regardless of
whether the water is to be reused or discharged. Pennsylvania State University has
completed a systematic investigation to characterize the solids in black water in coal
preparation plants (28).
POLYMERIC FLOCCULANTS
STABILIZATION OF WASTES
CONCLUSIONS
Tests were conducted with samples collected from preparation plants
throughout the United States. It was found that the mineral composition of black
water is largely determined by the nature of the adjacent roof and floor which are
introduced into the run-of-mine coal by overbreak during mining. The contribution
of coal associated mineral matter to the overall composition of black water was
minor in the sample evaluated.
Studies of the interaction of polymeric flocculants with coal and clay particles
revealed that these reagents are adsorbed more strongly on coal than on clay
minerals. The results have some important implications in the flocculation of black
water systems in which coal and clays are present simultaneously. For example, the
addition of sufficient polymer to give adequate flocculation of the clay minerals
could lead to considerable overdosage and consequent redispersion of the fine coal
particles. In addition, the very strong adsorption on the coal would give rise to
excessive reagent consumption.
Reject ponds are becoming increasingly impractical because of safety,
environmental, and land-use considerations. An alternative approach to the slurry
disposal of the fine wastes is the treatment of these wastes to create stable solids-a
process termed stabilization.
Under contract to DOE, Dravo Lime Company is conducting a study to
characterize the engineering, physical, and chemical properties that affect stabiliza-
tion of fine wastes from coal preparation plants. The requirements and conditions
for stabilizing these wastes with and without stabilizing agents are being determined.
Nine samples were collected from preparation plants in Pennsylvania, West
Virginia, Virginia, Illinois, and Indiana. All samples were subjected to laboratory
analyses for index properties—permeability, consolidation, penetration, and direct
shear; and stabilization characteristics—variations of additive type (Calcilox, lime,
Portland cement), dosage, waste solids level, temperature, and time. The data are
currently being analyzed and final report is to be issued in several months. If
additional research is warranted, a second phase involving on-site testing with a
mobile laboratory will be carried out.
The past year has been one of transition. Potential applications of coal
cleaning, and hence R&D goals, have been greatly affected by new environmental
legislation and impending energy legislation. Studies are now in progress to identify
the technical capability and costs of various coal cleaning technologies for removing
sulfur and other contaminants from coal. Progress has been made in the
development of physical cleaning techniques for improved pyrite removal and coal
energy recovery.
Progress continues in the development of chemical coal cleaning processes, but
impending environmental standards result in uncertainties concerning future market
applications.
248
-------
Methodologies have been developed for the environmental assessment of coal
preparation processes, ant) tests are scheduled to begin shortly. The conditions under
which trace elements are leached from coal preparation wastes have been identified,
and preliminary studies have identified the effectiveness of several pollution control
techniques.
CONVERSION FACTORS
ton = 0.907 metric tons
Ibm = 0.436 kg
Btu = 1055.6 joule
Btu/lb = 2326 joule/kg
in, = 2.54 cm
°C = 5/9 x (°F -32)
Ib./in. = 0.07 kg/cm2
249
-------
References
1. Gluskoter, H. J., et al. "Trace Elements in Coal: Occurrence and Distribution,"
EPA-600/7-77-064 (NTIS No. PB 270 922/AS), June 1977.
2. McCandless, L. C. "An Evaluation of Chemical Coal Cleaning Processes," Draft
Technical Report, EPA Contract 68-02-2199, January 1978.
3. Wewerka, E. M., et al. "Environmental Contamination from Trace Elements in
Coal Preparation Wastes: A Literature Review and Assessment," EPA-600/
7-76-007 (NTIS No. PB 267 339/AS), August 1976.
4. Kilgroe, J. D. "Coal Cleaning for Compliance with SC>2 Emission Regulations/'
Third Symposium on Coal Preparation, NCA/BCR Coal Conference and Expo
IV, October 18-20, 1977, Louisville, KY.
5. Min, S. and T. D. Wheelock. "Cleaning High Sulfur Coal," Second Symposium
on Coal Preparation, NCA/BCR Coal Conference and Expo III, October 19-21,
1976.
6. Cavallaro, J. A., M. T. Johnston, and A. W. Deurbrouck. "Sulfur Reduction
Potential of U.S. Coals: A Revised Report of Investigation," EPA-600/2-76-091
(NTIS No. PB 252 965/AS) or Bureau of Mines Rl 8118, April 1976.
7. Anon. "Replacing Orland Gas with Coal and Other Fuels in the Industrial and
Utility Sectors," Executive Office of the President—Energy Policy and Planning,
June I977.
8. McGlamery, G. G., et al. "Flue Gas Desulfurization Economics" in Proceedings,
Symposium on Flue Gas Desulfurization, New Orleans, March I976, Volume I,
EPA-600/2-76-136a (NTIS No. PB 255 317/AS), May I976.
9. Laseke, B. A., Jr., "EPA Utility FGD Utility FGD Survey: December
1977-January 1978," EPA-600/7-78-051a (NTIS No, PB 279 011/AS), March
1978.
10. Tuttle, J., A. Patkar, and N. Gregory. "EPA Industrial Boiler FGD Survey:
First Quarter 1978", EPA-600/7-78-052a (NTIS No. PB 279 214/AS), March
1978.
11. Hoffman, L., S. J. Aresco, and E. C. Holt, Jr. "Engineering/Economic Analysis
of Coal Preparation with SO2 Cleanup Processes for Keeping High Sulfur Coals
in the Energy Market," The Hoffman-Muntner Corporation for U.S. Bureau of
Mines, Contract J0155171, November I976.
12. Miller, K. J, "Flotation of Pyrite from Coal: Pilot Plant Study," U.S. Bureau
of Mines, Rl 7822, Washington, D.C., I973.
250
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13. Miller, K. J., "Coal Pyrite Flotation in Concentrated Pulps," U.S. Bureau of
Mines, Rl 8239, Washington, D.C., 1977.
14. Miller, J. D., "Adsorption-Desorption Reactions in the Desulfurization of Coal
by a Pyrite Flotation Technique," University of Utah for U.S. Bureau of
Mines, Contract HO 155169, Salt Lake City, Utah, April 1978.
15. Luborsky, F. E. "High Gradient Magnetic Separation for Removal of Sulfur
from Coal," General Electric Co. for U.S. Bureau of Mines Contract
H0366008.
16. Keller, D. V., Jr. "Surface Phenomena in the Dewatering of Coal," Syracuse
University for U. S. Bureau of Mines.
17. Hammersma, J. W. and M. L. Kraft. "Applicability of the Meyers Process for
Chemical Desulfurization of Coal: Survey of 35 Coals," EPA-650/2-74-025a
(NTIS No. PB 254 461/AS), September 1975.
18. Koutsoukous, E. P., et al. "Meyers Process Development for Chemical
Desulfurization of Coal, Volume I," EPA-600/2-76-143a (NTIS No. PB 261
128/AS), May 1976.
19. Hart, W. D., et al. "Reactor Test Project for Chemical Removal of Pyritic
Sulfur from Coal, Volume I," Draft Final Report, EPA Contract 68-02-1880,
April 1978.
20. Zavitsanos, P. D. "Coal Desulfurization Using Microwave Energy," EPA-600/
7-78-089, Washington, D.C., June 1978.
21. Personal Communication, E. P. Stambaugh, Battelle Columbus Laboratories,
May 1978.
22. Hangebrauck, R. P. "Environmental Assessment Methodology for Fossil Fuel
Energy Processes" in Symposium Proceedings: Environmental Aspects of Fuel
Conversion Technology, III, September 1977, Hollywood, Florida EPA-600/
7-78-063, April 1978.
23. Cleland, J. G. and G. L. Kingsbury. "Multimedia Environmental Goals for
Environmental Assessment, Volume I," EPA-600/7-77-136a (NTIS No. PB 276
919/AS), November 1977.
24. Lemmon, A. W., Jr. Environmental Assessment of Coal Cleaning Processes,
Draft of First Annual Report for the Period July 2, 1976 to September 30,
1977, Battelle Columbus Laboratories, Columbus, Ohio, October 1977.
25. Wewerka, E. M. and J. M. Williams. "Trace Element Characterization of Coal
Wastes-First Annual Report," EPA-600/7-78-028 (NTIS No. LA-6835-PR),
March 1978.
26. Cavallaro, J. A., G. A. Gibbon, and A. W. Deurbrouck. "A Washability and
Analytical Evaluation of Potential Pollution from Trace Elements in Coal,"
EPA-600/7-78-038 (NTIS No. PB 280757/AS), March 1978.
27. Wewerka, E. M. and J. M. Williams. "Trace Element Characterization and
Removal/Recovery from Coal and Coal Wastes," Progress Report for the Period
October 1, 1977 to December 31, 1977, EPA-IAG-D5-E681, Los Alamos, N.
M., 7 April 1978.
28. Apian, F. F., R. Hogg, and P. B. Bradley. "Control of Black Water in Coal
Preparation Plant Recycle and Discharge: Part 1, Characterization of Solid
Constituents," Penn State University for U.S. Bureau of Mines, Project No.
GO155158, University Park, Pa., July 1977.
251
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FLUE GAS DESULFURIZATION
OF COMBUSTION EXHAUST GASES
Norman Kaplan
Michael A. Maxwell
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
SMALL CONCENTRATIONS
DAMAGE
LEADING SOLUTION
FGD IN THE UTILITY
INPUSTRY
Fossil fuels, primarily coal, burned to produce electric power and generate
steam for various industrial uses contain up to about 5% sulfur. In the combustion
process almost all of this sulfur is converted to sulfur dioxide (SO2); thus, in the
case of a 5% sulfur coal, 100 grams of SO2 would be released for each kilogram of
coal burned. In the U.S. about 80% of all sulfur oxide emissions are from
combustion of fossil fuels.
Sulfur dioxide is considered by many to be harmful to human health and
damaging to materials and vegetation at extremely small concentrations (parts per
million) in the atmosphere. The National Air Pollution Control Administration, a
predecessor of the U.S. Environmental Protection Agency (EPA), fulfilling its
responsibility under the law, published an air quality criteria document for sulfur
oxides in 1969. Subsequently, ambient air quality regulations and new source
performance standards were established to control sulfur dioxide.
In order to support the regulations, EPA has fostered the development and
demonstration of various control technologies for sulfur dioxide since the early
1970's. This research and development work has included laboratory, pilot plant,
prototype and full scale utility demonstration of the technology under various
in-house and contractor-conducted programs.
Currently, flue gas desulfurization (FGD) is considered to be the leading
technically viable and economic near-term solution to control of sulfur oxide
emissions from combustion of high-sulfur coal. Generally, the high-sulfur coal
deposits are located in the industrialized, highly populated, eastern and midwestern
sections of the country where the consumption of coal is the highest. Most of the
low-sulfur coal is located in the west. Transportation of low-sulfur coal from west to
east in most cases turns out to be uneconomical.
In the past, poor reliability or dependability has been the prime criticism of
FGD. During the past half decade, however, dependability of utility systems has
improved markedly. Another criticism of FGD has been its high cost. Although the
cost issue has been the subject of much controversy in the past, with the present
data base, this issue can be put into more reasonable perspective. The cost of
generation of electricity is probably increased by 10% to 20% if an FGD system is
used for pollution control.
Use of FGD in the utility industry is projected to increase dramatically. Based
on currently known planned units, a 5-fold increase is projected in the next 8 years.
253
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THE PROBLEM
If we assume more stringent regulations will apply to the utility industry (revised
new source performance standards) we might expect an order of magnitude increase
in the same period.
Based on recent EPA estimates, about 26 to 30 million metric tons per year
of sulfur oxides are emitted to the atmosphere in the United States by various
combustion and other industrial processes. This is equivalent to emission of about
140 liters of SC>2 for every man, woman and child in the country each day!
The majority of sulfur oxide emissions come from a relatively small variety of
sources. About 80% of all emissions are from stationary source fuel combustion and
about two-thirds of all emissions are from the electric utility industry. The
remaining 20% of emissions are mainly from a few industrial processes: metals
smelting and refining, petroleum refining, minerals products processing, and chemicals
manufacturing. In 1976 almost 60% of these industrial emissions came from the
metals industries with the remainder being divided somewhat evenly among the other
three mentioned areas.
30-,
c
p
CD
O
C/3
LLJ
LU
z
O
§
LU
X
O
to
20-I
10-
29.1
29.7
TOTALS
15.7
6.6
28.8
27.9
15.6
5.9
28.2
26.9
25.7
ELECTRIC UTILITIES
16.0
17.5
5.4
17.0
16.7
17.6
NON-UTILITY STATIONARY FUEL COMBUST
5.9
5.5 6.1 5.8 5.3 4.2
INDUSTRIAL PROCESSES
3.9
MISCELLANEOUS 0.9 1.0
4.3
4.1
1970
YEAR
FIGURE ^-Nationwide SOX emission estimates, 2970 - 1976
Source: (EPA, 1977)
\ \ \\
1971 1972 1973 1974 1975 1976
254
-------
7-
6-
o
CD
£ 5-
O
CO
CO
CO
LLJ
X
O
CO
4-
3-
2-
1-
6.1
5.9
4.1
0.5
0.5
0.6
5.5
3.6
0.6
0.5
0.6
MET
4.0
MINER/
0.6
CHEM
0.6
PETROL
0.7
5.8
ALS
3.7
<\LPROC
0.6
CALS
0.5
.EUM RE
0.8
5.3
3.3
)UCTS
0.6
0.4
FINING
0.8
MISCELLANEOUS 0.2
4.2
2.5
0.5
0.3
0.7
TOTALS
4.1
2.4
0.5
0.3
0.7
70
71
74
FIGURE
Source:
72 73
YEAR
2—SOx emissions from industrial processes, 1970 - 1976
(EPA, 1977)
75
76
DATA SHOW DOWNTREND
These national and industrial process SOX emissions are presented graphically
in figures 1 and 2, respectively. Figure 2 is a breakdown of the total industrial
process emissions shown in figure 1. The data indicate that our national emissions of
sulfur oxides are being stabilized and even show a downtrend. Apparently, the
downtrend is due mainly to lower emissions from the industrial process sources
which show a reduction of one-third between 1972 and 1976, mainly due to metals
smelting and refining.
REGULATION
It is obvious from these data that adequate control of sulfur oxides in our
atmosphere will depend on control of sulfur oxide emissions in combustion exhaust
gases. With our Nation's commitment to use our coal reserves for energy production,
this fact is even further emphasized.
Sulfur dioxide is federally controlled under the Clean Air Act (amended
August 1977) in two basic ways: by emission limitations and by promulgated
ambient air quality standards. The states and municipalities may enact (and some
have enacted) legislation and/or regulation which is more stringent than the federal
laws and regulations.
255
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LIMITATIONS
FALL-BACK POSITION
STATE IMPLEMENTATION
PLANS
Emission limitations on sulfur dioxide are imposed on new fossil fuel-fired
steam generators by regulations promulgated on December 23, 1971. These
regulations apply to steam generators with a heat input of more than 73 MW (250
million Btu/hr) and for which construction or modification was initiated after
August 17, 1971 (the date of proposal of the standards). The regulations limit
emissions to 520 ng/J (1.2 Ib/million Btu) heat input for solid fuels (e.g., coal) and
340 ng/J (0.8 Ib/million Btu) heat input for liquid fuels (e.g., oil).
As an example, this limitation requires removal of more than 70% of the
sulfur dioxide emitted when burning a coal containing 3% sulfur and having a
heating value of 28,000 J/g (12,000 Btu/lb). These limitations apply to almost all
utility boilers and some large industrial boilers.
The EPA is currently considering revision of these new source performance
standards (NSPS) to be more stringent for the larger boilers (over 73 MW input).
Regulation of emissions from the smaller boilers is also being considered. Current
thinking is that NSPS should require 85% to 90% SC>2 removal with credit given for
precombustion processes for sulfur removal from fuel. The 520 ng/J (1.2 Ib/million
Btu) limitation would still be a ceiling, applicable to extremely high sulfur coals;
however, if emissions from a source burning low sulfur coal were below 90 ng/J
(0.2 Ib/million Btu), no further reduction would be required even if the 85% to
90% reduction were not being attained. To temper these limitations somewhat, an
allowance of 3 days per month during which SO2 removal could drop to as low as
75% is also being considered.
It is interesting to note that in the early 1970's the NSPS requirements were
thought to be stringent and considered to be the limiting maximum requirement in
the law. With several legal precedents on enforcement, the NSPS are now considered
a limiting minimum requirement in the law. With aspects of environmental law
including Prevention of Significant Deterioration, use of Best Available Control
Technology, and Lowest Achievable Emission Rate, the NSPS are now considered a
fall-back position in enforcement of the law.
As mandated by the Clean Air Act, EPA's administrator has promulgated
primary and secondary national ambient air quality standards (NAAQS) for S02.
Primary standards are designed to protect the public health, while secondary
standards are meant to protect the public welfare. These standards are given in table
1.
While the NSPS directly limit emissions from certain new sources, the NAAQS
indirectly control emissions from all sources.
To meet the primary standards, the Clean Air Act amendments require each
state to adopt (and submit to the administrator) a State Implementation Plan (SIP)
to provide for implementation, maintenance, and enforcement of the primary
standard as soon as practicable, but not later than 3 years from the date of
approval of the SIP. Requirements of the SIP to implement, maintain, and enforce
TABLE 1
National ambient air quality standards for SC>2
Annual Mean
Maximum 24— hour
Concentration*
Maximum 3— hour
Concentration*
Primary
80 ;ug/m3
(0.03 ppm)
365 /jg/m3
(0.14 ppm)
_
Secondary
-
1,300 /j/m3
(0.5 ppm)
*Not to be exceeded more than once a year
256
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LOW SULFUR FUELS
COAL CLEANING
PHYSICAL COAL CLEANING
CHEMICAL COAL CLEANING
the secondary standard must specify "a reasonable time at which such secondary
standard will be attained." The Clean Air Act amendments of 1977 require review
of the criteria documents and NAAQS for sulfur oxides before 1980.
To control SOX emissions from combustion sources, we can (1) use fuels
containing less sulfur, (2) remove sulfur from the fuel before combustion (coal
cleaning and fuel processing), (3) remove sulfur during combustion (fluid bed
combustion), (4) remove sulfur from the flue gases after combustion (FGD), or (5)
any combination of the above.
In line with a reasonable and forward looking national energy policy, we
cannot rely to any great extent on naturally occurring low-sulfur oil and natural gas
as a means of controlling SOX emissions from stationary combustion sources.
Generally, low-sulfur coal deposits are located in the western part of the U.S. In the
highly industrialized and populated east and midwest, where much of the coal will
be burned, predominantly high-sulfur coal is mined. Transportation of low-sulfur coal
from west to east is usually not economical even when compared with using FGD
with high-sulfur coal.
In 1975 and 1976 nearly 100% of the new fossil fuel fired electrical
generating capacity ordered by U.S. utilities was coal-fired. In 1977, 100% of the
ordered generating capacity was coal-fired (Richards, 1978).
Use of low sulfur coal may be a reasonable option for some existing facilities
now burning coal; however, with potential requirements of revised federal NSPS
requiring 90% sulfur removal, use of low sulfur coal, alone, at new coal burning
facilities may not be acceptable. It has been estimated (Ponder et al., 1976) that
even with the present NSPS, low-sulfur coal production in 1980 will supply less
than 44% of the utility industry's coal demand.
Techniques for removing sulfur from coal prior to combustion include physical
or chemical coal cleaning and the generation of clean synthetic fuels. The former
deals with removal of inorganic sulfur-containing matter (e.g., pyrite and sulfate)
that is physically associated with the coal. The latter deals with sulfur that is
chemically bound to the organic structure of the coal.
Physical coal cleaning, based on the difference in specific gravities or surface
properties of the inorganic matter and the remainder of the coal, has been in use
for years. From 20% to 80% of the pyritic sulfur can be removed, depending on the
coal and techniques used. It has been estimated (Ponder, et al., 1976) that less than
13.5% of our coal reserves can be physically cleaned to meet present NSPS.
Obviously, in complying with more stringent NSPS, physical coal must be used with
FGD or in combination with other controls.
Currently, 50% of the domestically consumed coal is physically cleaned to
remove mineral matter and mining residue. A portion of the metallurgical grade
coals is also cleaned to remove sulfur. Cleaning operations for steam coals have not
previously been designed and operated to remove sulfur for compliance with SC^
emission regulations. The first U.S. steam coal preparation plant, designed to remove
sulfur for compliance with state and federal SC^ emission regulations, has just begun
operation at Homer City, Pennsylvania. Two other sulfur removing plants are being
planned by the Tennessee Valley Authority (TVA). None of these steam coal plants
incorporate the most advanced physical preparation techniques now used in the
metallurgical and mineral industries.
Chemical coal cleaning processes vary substantially because of the different
chemical reactions which can be used to remove sulfur and other contaminants from
coal. Chemical coal cleaning processes usually entail grinding the coal to small
particles and treating these particles with chemical agents at elevated temperatures
and pressures. The coal's sulfur is converted to elemental sulfur or sulfur compounds
which can be physically removed from the coal structure. Some chemical leaching
processes, such as the TRW-Meyers Process, remove only pyritic sulfur. Other less
advanced processes, such as that under development by the Department of Energy
(DOE), are capable of removing organic and pyritic sulfur.
257
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FLUID BED
FLUE GAS DESULFURIZATION
Chemical coal cleaning processes are currently under development at the bench
and pilot scales. Optimistically, several chemical processes could be ready for
commercial demonstration in 3 to 5 years.
These processes, atmospheric and pressurized, remove sulfur from coal during
combustion by burning the coal in a fluidized bed of limestone or dolomite. The
sulfur in the coal reacts with the bed reagent to form dry calcium sulfate. A
portion of the fluid bed is continuously withdrawn to remove the sulfur compounds
either by direct disposal or by regeneration of the spent bed material. These
processes are currently at the pilot/prototype development stage and may reach
commercialization by 1985-1990. This technology will be suitable for new large
combustion processes and is projected to be less costly than FGD. One process
advantage over the nonregenerable wet scrubbing FGD processes is that these
processes produce a dry solid waste product rather than a sludge. A process
disadvantage is that fluid bed combustors require a much higher consumption of
limestone for the same amount of sulfur removal than does a wet limestone FGD
system. Consequently, the cost may in fact be higher than that for FGD.
Flue gas desulfurization is the removal of sulfur oxides from combustion
exhaust gases in most cases by chemical reaction with an absorbent in water slurry
or solution in an absorption tower. The tower is known as a scrubber, thus the
common terminology, wet scrubbing. Basically, a scrubber is a device in which
gas/liquid contact occurs. Certain other FGD processes under development remove
the sulfur oxides by dry adsorption.
PROCESSES IN CURRENT
USE
Well over 50 FGD processes have been invented; many have undergone testing
in small scale laboratory or pilot-plant operations. But relatively few have served to
date for SO2 control of full scale utility and industrial boilers in this country. On
the other hand, considering our commitment to coal and the potentially more
stringent pollution control regulations, increased use of FGD may well be the only
near-term available course of action.
There are currently six types of FGD processes in use for control of S02
emissions from full scale utility systems. These are summarized in table 2 by process
type, number of systems, controlled generating capacity, and percentage of the total
for each type.
TABLE 2
Operating utility FGD systems
Process
Limestone Slurry
Scrubbing
Lime Slurry Scrubbing
Lime/Alkaline Fly Ash
Scrubbing
Soda Ash Solution
Scrubbing
Magnesium Oxide
Scrubbing
Wellman-Lord/Allied
Chemical
No. of
Units
11
10
3
3
1
1
Controlled
Generating
Capacity, MW
5233
3517
1170
375
120
115
Capacity,
% of
Total
50
33
11
4
1
1
Totals
29
10530
100
Source: (Laseke, 1978)
258
-------
TABLE 3
Operating nonutility FGD systems
Process
No. of
Units
Controlled MW
Capacity Equivalent
in., actual* Controlled
Capacity,
% of
Total
Soluble Alkali
Scrubbing, Throwaway
(Na, NH3, alkaline
waste)
Dual Alkali
Lime Slurry
Limestone Slurry
Totals
27
5
1
1
34
4,360,000
542,000
280,000
73,000i
5,255,000
1362
169
88
23
1642
83
10
5
2
100
*3200 acfm (actual cubic feet/min) = 1 MW
fEstimated to conform with other figures in the table
Source: (Tuttle et al., 1978)
SALABLE AND THROWAWAY
THROWAWAY FAVORED
SLURRY SCRUBBING
The mix of FGD systems currently applied at nonutility stationary-source
combustion systems is summarized in table 3.
The various FGD processes may be divided into two categories: regenerable
and nonregenerable (perhaps more properly into salable product and throwaway
processes). The regenerable or salable product processes produce sulfur or a
by-product containing sulfur which may be sold to partially offset the cost of
operation of the FGD system. The potential products are elemental sulfur, sulfuric
acid, liquid SC>2, and possibly gypsum if there is a market for the sale of it.
(However, if impure gypsum is produced and is disposed of as solid waste, the
system would be classified as throwaway.) Throwaway or nonregenerable systems
produce a liquid, solid, or sludge waste product containing the sulfur removed from
the flue gases. Of the systems appearing in tables 2 and 3, only the magnesium
oxide and Wellman-Lord/Allied Chemical are salable product processes.
Based on current controlled capacity, 98% of the operating utility processes
and 100% of the nonutility processes are throwaway systems. The throwaway
processes are heavily favored in current application due to more favorable
economics, simplicity, and prior experience with previous applications relative to the
salable product processes.
It is also interesting to note that, while only 4% of the utility systems (the
soda ash systems) produce a sizeable liquid waste stream, 83% of the nonutility
applications (soluble alkali, throwaway) produce such a stream. In general, disposal
of large volumes of liquid wastes containing soluble solids is environmentally
unacceptable. Also, the cost of soluble alkali reagents is higher than calcium based
alkali. In most cases a permit for such operations must be secured from the
appropriate regulatory authority. Since utility systems are generally larger than
nonutility systems, discharge permits for such operation may be less likely
obtainable and reagent cost considerations thus become more significant. Most
soluble throwaway systems either treat the soluble waste stream to reduce chemical
oxygen demand (COD) and then feed the waste through some municipal wastewater
process, or simply evaporate the liquid. As we aim toward zero discharge, however,
these once-through soluble scrubbing systems will become less prevalent.
Brief descriptions of most of the significant U.S. operating systems are given
below.
In concept, lime or limestone slurry scrubbing processes are very simple. In
practice, however, the chemistry and system design for a full-scale operation can be
more complex than seems evident at first glance.
259
-------
LIMESTONE SLURRY
LIME SLURRY
These systems use a slurry of lime or limestone in water to absorb S02 from
power plant flue gas in a gas/liquid scrubber. The slurry generally ranges from 5% to
15% solids. Various types of scrubbers or gas/liquid contact devices are employed
commercially: spray towers, grid towers, plate towers, Venturis, marble-bed scrubbers
(packed beds of glass spheres) and turbulent-contact absorbers (lightweight hollow
plastic spheres— ping-pong balls— held between restraining grids in a countercurrent
scrubbing tower). These scrubbers usually operate with a liquid-to-gas (L/G) ratio of
6 to 15 1/normal m3 (40 to 100 gal. 71,000 actual ft3).
A schematic of the 10 MW prototype limestone system at the TV A/EPA test
facility at TVA's Shawnee steam plant, figure 3, shows a turbulent-contact absorber
with an open-chevron mist eliminator. Flue gas flows up through the tower and
contacts slurry which sprays down over the packing, countercurrent to the gas
stream. The gas/liquid counterflow keeps the spheres in turbulent motion, which
improves gas/liquid contact.
The overall absorption reaction taking place in the scrubber and the hold-tanks
for a limestone slurry system produces hydrated calcium sulfite:
+ S02 + 1/2 H2O * CaSOs-1/2 H2O + CO2 (1)
With a lime slurry system, the overall reaction is similar but yields no C02:
CaO + S02 + 1/2 H2O " CaSOs-1/2 H20 (2)
(The actual reactant in Equation 2 is Ca(OH>2, since CaO is slaked in the slurrying
process.)
In practice, some of the absorbed SO2 is oxidized by oxygen which is also
absorbed from the flue gas. This shows up in the slurry as either gypsum (CaS04-2
H-O) or as a calcium sulfite/sulfate mixed crystal [Ca(SO3)x(SO4)y'z H2Q4] .Slurry
is recycled around the scrubber to obtain the high liquid-to-gas ratios required. A
bleed stream is taken from the scrubber liquid circuit to remove the calcium-sulfur
compounds formed. This is accomplished by thickening, filtration, ponding, and
various combinations of these operations. The calcium-sulfur compounds are solids to
be disposed; the liquor separated is usually recycled to the system.
z±\
TCA
SCRUBBER
r
TO EFFLUENT
FLUE GAS HOLD TANK
LIMESTONE
^=>
SCRUBBER
EFFLUENT
HOLD TANK
$W
AAA
1 'J • Jl-'ir't
i £*££•£
,T
•*•
I.D. FAN
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MAKE-UP PROCESS WATER
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*-
IFIER
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,
J
DISCHARGE
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-*
-€
I
I
RESUURRY
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SETTLING POND
GAS STREAM
LIQUOR STREAM
FIGURE 3—Schematic of wet limestone scrubbing system
260
-------
ALKALINE FLY ASH
SCRUBBING
SODA ASH SCRUBBING
MAGNESIUM OXIDE
SCRUBBING
Lime and limestone slurry scrubbing systems can be engineered for almost any
desired level of S02 removal. Commercial utility systems are generally designed for
80% to 90% removal; however, some systems have at times achieved more than 99%
removal. The higher removal rate is not incrementally very costly: investment savings
realized in designing for 80% rather than 90% SO2 removal amount to only about
3.2% to 4.5% (Slack and Hollinden, 1975).
Western U.S. low-sulfur coals appear particularly suitable to S02 control by
scrubbing the waste gases with a slurry of the alkaline fly ash which results from
the combustion process. There are two ways to add the alkaline ash to the system:
(1) collecting the fly ash in an electrostatic precipitator upstream of the scrubber
and then slurrying the dry fly ash with water so that it can be pumped into the
scrubber circuit, and (2) scrubbing the fly ash directly from the flue gas by the
circulating slurry of fly ash and water.
Most western coals have a low sulfur content (less than 1.0%). They also
usually have a low heating value and consequently require close control to hold
their combustion emissions within current federal limits for NSPS defined as mass
emissions per unit heat input. While typical eastern bituminous coals have heating
values of about 28,000 J/g (12,000 Btu/lb), lignite coals may have heating values as
low as 16,000 J/g (6,800 Btu/lb). The bituminous coal could contain as much as
0.7% sulfur and still meet the NSPS limitation of 520 ng/J, without controls; but
the lignite would have to have no more than about 0.4% sulfur due to its lower
heating value.
Generally, the coals best suited to this method are the western lignites and
subbituminous coals. Certain of these coals (e.g., those from North Dakota, Montana
and Wyoming) contain up to 20% ash; and the ash contains up to 40% alkaline
constituents including oxides of calcium, magnesium, sodium and potassium, some of
which are offset by acidic constituents (Ness et al., 1977). With potentially more
stringent NSPS, this process may, however, have to be used with supplemental lime
or limestone to meet standards.
This method of controlling S02 involves scrubbing the flue gas with a solution
of sodium carbonate and bicarbonate, to produce a mixture of sodium sulfite and
sulfate by these reactions:
(3)
(4)
(5)
SO2 " Na2SO3 + C02
2 NaHCCs + S02 + H20 "* Na2S03 + 2 H2O + 2 CC-2
Na2S03 + 1/2 02 * Na2S04
The sodium carbonate does not have to be pure. Nevada Power Company uses trona
salt, a naturally-occurring mineral containing 60% NaHCOo, 20% NaCL, 10% sulfates,
and 10% insolubles.
This process has definite limitations in large-scale utility applications, since it
requires a relatively cheap source of sodium carbonate or bicarbonate and an ability
to dispose of large volumes of waste salt solution. Nevada Power is located near
trona deposits—in an area where natural evaporation rates far exceed rainfall and
where land is relatively abundant. The company processes its liquid waste in solar
evaporation ponds and deposits the crystallized waste salts back at the mine.
The magnesium oxide process is a regenerable or salable product process. It
does not produce waste material—SO2 removed from the flue gas is concentrated
and used to make marketable H2SO4 or elemental sulfur.
Employing a slurry of MgO—or Mg(OH)2—to absorb S02 from flue gas in a
scrubber, this process yields magnesium sulfite and sulfate. When dried and calcined,
the mixed sulfite/sulfate produces a concentrated stream (10% to 15%) of SC>2 and
regenerates MgO for recycle to the scrubber. Carbon added to the calcining step
reduces any MgSO4 to MgO and SO2.
261
-------
WELLMAN-LORD SYSTEM
SOLUBLE ALKALI
SCRUBBING
DUAL ALKALI
BISULFITE FORMED
In commercial applications, the scrubbing and drying steps would normally
take place at the power plant. The regeneration and H2SO4 production steps might
be performed at a conventional sulfuric acid plant. Alternatively, a central processing
plant could produce sulfur from mixed magnesium sulfite/sulfate brought in from
several desulfurization locations.
The Wellman-Lord process (sold by Davy Powergas, Inc) is also a regenerable
or salable product system. When coupled with other processing steps, it can make
salable liquid S02, HjSO^, or elemental sulfur.
The W-L process employs a solution of Na2SOs to absorb SO2 from waste
gases in a scrubber or absorber, converting the sulfite to bisulfite:
Na2S03 + S02 + H20 * 2 NaHSOs
(6)
Thermal decomposition of the bisulfite in an evaporative crystallizer regenerates
sodium sulfite for reuse as the absorbent:
Na2SOs + S02 + H20
(7)
The evaporative crystallizer produces a mixture of steam and S02 and a slurry
containing sodium sulfite/sulfate plus some undecomposed NaHSOs in solution. As
water condenses from the steam/S02 mixture, it leaves a wet S02-enriched gas
stream to undergo further processing for recovery of salable sulfur values.
Most industrial boilers use a soluble alkali scrubbing process—basically as
described for soda ash scrubbing, and using sodium carbonate, bicarbonate,
hydroxide, or ammonia based alkali—which converts sulfur in the flue gas to
sulfite/bisulfite and sulfate in solution.
For spent scrubbing liquors, disposal practices include consume in pulp/paper
manufacturing, discharge to evaporation ponds, treat (mainly by air oxidation) and
discharge to city sewer system, and treat and discharge to rivers.
Some sodium-alkali users are considering regeneration of scrubber liquor by
treating the spent liquor with calcium hydroxide. This would actually give them dual
alkali systems with the attendant advantage of eliminating a liquid-waste stream.
Table 3 shows that dual alkali systems have become the second most prevalent
type of S02 control for industrial boilers. They may become the first choice as
more sodium alkali systems are converted to dual alkali in the face of new
regulations that may limit disposal of liquid wastes containing large amounts of
dissolved salts.
Dual alkali processes, like lime/limestone slurry scrubbing, are throwaway
systems. In the operation as a whole, lime is consumed to produce a wet solid
waste (mainly calcium sulfite/sulfate) just as in lime slurry scrubbing. In addition,
however, dual alkali systems require a small amount of sodium alkali makeup.
A solution of sodium sulfite/bisulfite and sulfate in a scrubber will absorb S02
from the flue gas or other waste gas. Only the sulfite is active in absorbing S02,
forming bisulfite as in the Wellman-Lord system:
Absorption: S03 + S02 + H20 " 2 HSOJ
(8)
The bisulfite-rich liquor, treated with lime in a reaction tank, regenerates active
alkali for recycle to the scrubber:
Regeneration: 2 HSOs + Ca(OH>2 " SO3 + CaSOs + 2 H20
S04 + Ca(OH)2 "2 01-T + CaS04
(9)
(10)
The sulfate and sulfite precipitate as a hydrated mixed crystal, or as a gypsum
phase (CaS04'2 H20) plus a hydrated mixed crystal, depending upon the
262
-------
AUTHORITY PROVIDED
FGD DEVELOPMENT-
HIGH PRIORITY
MAJOR OBJECTIVES
concentration of dissolved species. Also, depending upon solution concentrations, the
mixed crystal is predominantly calcium sulfite, with up to about 25% calcium
sulfate co-precipitated. Sulfite/bisulfite oxidation by oxygen in the flue gas produces
sulfate in the system.
The 1970 and 1977 Amendments to the Clean Air Act provide the authority
for EPA's current research, development, and demonstration program in the FGD
area. EPA's FGD RD&D program is conducted by the Industrial Environmental
Research Laboratory at Research Triangle Park, N.C. (IERL-RTP). The primary
purpose of this program has been to improve, develop, and demonstrate reliable,
cost-effective and environmentally acceptable FGD processes for reducing SOX
emissions from both existing and new stationary combustion sources.
EPA has been aided in this effort by at least two other federal organizations,
the Tennessee Valley Authority (TVA) and the U.S. Bureau of Mines (USBM). For
example, EPA's key program in the nonregenerable area is the lime/limestone
prototype test program at TVA's Shawnee Steam Plant (near Paducah, Kentucky),
and a major regenerable process (citrate) demonstration unit is being built at a St.
Joe Minerals plant based on pilot paint work by USBM.
In the federal energy/environment research and development program, FGD
technology development has been given a high priority. Studies by EPA indicate that
FGD is competitive in cost with advanced control methods, such as chemical coal
cleaning and fluidized bed combustion; therefore, FGD should play an important
role in controlling emissions at least until the end of the twentieth century.
This technology has progressed rapidly in part due to financial aid passing
through the Federal interagency program. Several FGD studies, pilot plants,
prototypes, and demonstration-scale facilities have been funded by EPA. Progress has
been achieved in FGD development by the private sector; however the overall pace
of development was increased by the initiation of the federal interagency effort.
Some of the more significant current federal FGD programs are summarized
below.
An important part of the lime/limestone development effort involves the
operation of a prototype scrubbing test facility, the TVA Shawnee Steam Plant. This
versatile facility allows comprehensive testing of two 10 MW scrubber types under a
variety of operating conditions. Bechtel Corporation of San Francisco designed the
test facility and directs the test program. TVA constructed and operates the facility.
The major concerns of the utility industry to date regarding lime/limestone
scrubbing have centered on scaling and plugging potential, the large quantities of
waste sludge generated, and the high costs (capital and operating) of scrubbing. It is
toward these areas of concern that the Shawnee program has been directed.
Major objectives of the original 2-year test program were (1) to characterize
fully the effect of important process variables on S02 and particulate matter
removal, (2) to develop and verify mathematical models to allow scaleup to full-scale
scrubber facilities, (3) to study the technical and economic feasibility of
lime/limestone scrubbing, and (4) to demonstrate long-term reliability. Later the
Shawnee program was extended and the scope was expanded to investigate promising
equipment and process variations to (1) minimize costs, energy requirements, and
quantity (and improve the quality) of the sludge produced, (2) maximize S02
removal efficiency, (3) develop a design/economic study computer program, and (4)
improve system control and operating reliability, especially in the mist eliminator
area. Of particular interest were studies of forced oxidation, increased alkali
utilization, and MgO or other additives to increase S02 removal efficiency and to
force subsaturated gypsum operation. Subsaturated operation was first established in
the EPA pilot FGD scrubber and later tested at Shawnee. The main advantage of
subsaturated operation is reduced scaling in scrubber systems.
The Shawnee program has made major contributions toward improvement of
lime and limestone scrubbing technology. The most significant results to date include
263
-------
PILOT FGD SCRUBBER
PROGRAM
INDUSTRIAL BOILER FGD
SYSTEM
LIME SCRUBBING TEST
PROGRAM
(1) demonstration that conventional lime/limestone systems can be operated reliably
on a 10 MW level (two separate reliability problems have been identified-scaling and
accumulation of soft mud-type solids—and methods to control each have been
demonstrated), (2) mud-type solids deposition was shown to be a strong function of
alkali utilization and at high utilization (greater than about 85%) these solids are
much more easily removed, (3) equipment or process variations were demonstrated
which individually improved alkali utilization, reduced costs, reduced sludge volumes,
improved S02 removal efficiency, and favorably influenced the system chemistry,
and (4) development of useful industrial tools, such as the design/economic study
computer program and the computerized Shawnee data base. (Williams, 1977)
The FGD pilot plant operated by Acurex at IERL-RTP consists of two
scrubbers having a flue gas capacity of about 0.1 MW. They have been in operation
since 1972 to provide in-house experimental support for EPA's larger, prototype
scrubber test facility at the Shawnee Steam Plant. The IERL-RTP scurbbers have 1%
of the capacity of the Shawnee prototypes and are 1/1000 the size of a small
full-scale utility system. In addition to supporting Shawnee, the pilot plant also
provides IERL-RTP with the capacity to independently evaluate new concepts in
lime/limestone scrubbing technology. Many of the new concepts tested at Shawnee
were first conceptualized and developed in the IERL-RTP pilot plant.
Currently, plans to modify the pilot plant, to allow testing of dual alkali
systems, are being formulated. The pilot plant will be designed to test dual alkali
systems with either lime or limestone regeneration. This allows the in-house pilot
plant to support EPA's development and demonstration efforts in dual alkali
technology as it has supported the lime/limestone program in the past.
EPA has sponsored an 18-month test program at a lime/limestone industrial
boiler FGD system installed to control S02 and particle emissions from seven small
coal-fired heating boilers (approximately 23 MW equivalent, total) at the
Rickenbacker Air Force Base near Columbus, Ohio. The FGD system was installed
under contract between the Air Force and Research Cottrell, the U.S. licensee for
the A. B. Bahco lime/limestone scrubbing process. This process was developed by A.
B. Bahco, a Swedish company, and is reported to be particularly well suited for
industrial boiler applications in that it is manufactured in standard sizes in the range
of 5-50 MW equivalent and is adaptable to a high degree of automation. The
application of the Bahco scrubber at Rickenbacker was the first such installation in
the U.S. and the first anywhere on a coal-fired industrial boiler.
Although numerous mechanical problems have been encountered since startup
in March 1976, the operation has improved to the extent that 95% availability has
been demonstrated for approximately one-half year. There were no problems with
scale formation or plugging with either lime or limestone and the system easily met
or exceeded all emission and operating cost guarantees. A final report on this
program is currently being prepared for general publication.
In the spring of 1976 a test program was initiated at the Paddy's Run plant
of LG&E. Some of the objectives of the program were to compare carbide lime
with ordinary commercial lime in the operation of a full scale system, to test the
gypsum subsaturated mode of operation with both absorbents, and to investigate the
effects of magnesium oxide and chloride addition to the system. Scrubber testing
took place between the fall of 1976 and the summer of 1977, with Radian
conducting the system analysis and evaluation.
It was found that, whereas subsaturated operation was achieved with carbide
lime, similar operation with commercial lime did not give the same result. A major
finding of the program was that carbide lime contained trace quantities of an
oxidation inhibitor (suspected to be thiosulfate) which promoted subsaturated
operation. Subsaturated operation was eventually achieved at LG&E with commercial
lime with the addition of magnesium oxide in small quantities.
Final reports on both the LG&E scrubber testing and carbide lime
characterization studies are being prepared for general publication.
264
-------
DUAL ALKALI
DEMONSTRATION
WELLMAN-LORD/ALLIED
CHEMICAL SYSTEM
AQUEOUS CARBONATE
DEMONSTRATION
CITRATE DEMONSTRATION
In September 1976, EPA contracted with LG&E for cost-shared, full-scale
coal-fired utility demonstration of the dual alkali process at the 280 MW Cane Run
No. 6 boiler. The demonstration project consists of four phases: (1) design and cost
estimation, (2) engineering design, construction, and mechanical testing, (3) startup
and performance testing, and (4) 1 year of operation and long-term testing.
Construction is expected to be complete by the end of 1978, and testing will begin
in early 1979.
The FGD system was designed by Combustion Equipment Associates and
Arthur D. Little, Inc. and is currently being constructed by LG&E. In June 1977 a
contract was established with Bechtel National, Inc. in San Francisco to design and
conduct a test program to evaluate the system installed at LG&E.
A report on the Phase 1 preliminary design and cost estimate for the system
was published in January 1978 (Van Ness et al., 1978). In addition to the design
and cost estimate for the LG&E system, it also gives cost projections for similar
hypothetical systems in the 500 and 1000 MW range. The report projects the LG&E
system costs at less than $60/kW capital cost and less than 3 mills/kWhr annualized
operating costs in 1976 dollars.
EPA and Northern Indiana Public Service Company (NIPSCO) have jointly
funded the design and construction of an FGD demonstration plant using the W-L
SC>2 recovery process and the Allied Chemical SC>2 reduction process to convert
recovered SC>2 to elemental sulfur. The operational costs for the system will be paid
by NIPSCO, and a comprehensive test and evaluation program, conducted by TRW
Corporation, will be funded by EPA. The demonstration system has been retrofitted
to the 115 MW, coal-fired unit 11 at the D. H. Mitchell Station in Gary, Indiana.
The demonstration program consists of three phases: Phase I, the development
of a process design, major equipment specification, and a detailed cost estimate, was
completed in December 1972. Phase II, the final design and construction, was
completed by Davy Powergas, Inc. in August 1976.
Between August 1976 and August 1977 various problems involving both the
boiler and the FGD system (primarily the boiler) delayed the acceptance tests,
which eventually were conducted during the first half of September 1977. During
the acceptance tests, system performance exceeded all performance criteria tested,
including S02 removal (91% attained, 90% required), particle emissions, utility costs,
sodium barbonate consumption, and sulfur product purity. The system is currently
undergoing Phase III, long-term testing.
EPA and Empire State Electric Energy Research Corporation (ESEERCO), a
research orgainzation sponsored by New York's eight major power suppliers, have
contracted to fund jointly the design and construction of a demonstration of
Atomic International's sulfur-producing aqueous carbonate process. The
demonstration is being retrofitted to a 100 MW boiler at Niagara Mohawk Power
Company's coal-fired Huntley Station in Tonawanda, New York.
The demonstration will be in four phases. Phase I, the design and cost
estimate, was completed in May 1977. Phase II, construction, is expected to begin
by the end of 1978. Phase III, acceptance testing, and Phase IV, demonstration
testing, will follow.
EPA and USBM have entered into a cooperative agreement to pool funds and
technical talents to demonstrate the citrate process, a regenerable sulfur producing
process, which has been deveJoped through pilot scale by USBM. A concurrent
development program, carried out by an industrial consortium headed by Pfizer
Chemical Company, also led to a pilot operation of the process. Based on the
results of these two pilot programs, EPA and USBM have initiated the
demonstration of this technology on a 50 MW coal-fired boiler at St. Joe Minerals
Corporation in Monaca, Pennsylvania.
The demonstration will be in four phases. Phase I, the design and cost
estimate, was completed in November 1976. Phase II, detailed design, procurement,
265
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OTHER FEDERALLY FUNDED
PROJECTS
CURRENT FGD STATUS
and construction, began in March 1977 and is scheduled to be completed in October
1978. Acceptance testing, Phase III, should be accomplished by the end of 1978, at
which time a 1-year test and evaluation program, Phase IV, will be initiated.
In addition to the current pilot and demonstration programs, previously
discussed, other federally funded activities in the FGD area include the Shawnee
TVA/EPA 150 MW dry limestone process demonstration, the 150 MW magnesium
oxide process demonstration at Boston Edison, the Cat-Ox process demonstration at
Illinois Power, the laboratory/pilot-plant/prototype development program conducted
by A. D. Little (prototype at Scholz Plant of Gulf Power), the TVA pilot plant
work at the Colbert Steam Plant, the General Motors industrial boiler FGD test
program, and the Key West limestone scrubbing test program. These programs are
now completed; some are considered successful, others are not.
In addition to the many development/demonstration projects, the federal
programs also include several engineering and survey projects with the general
purpose of developing information on FGD and associated areas for use by the
government, the equipment and system developers, and the ultimate users of the
technology. These projects, generally classified as FGD support studies and
technology transfer activities, tend to complement each other. Included here are the
TVA/EPA By-product Marketing Studies, the Reductant Gas Process Study, a reheat
assessment study, sludge fixation and disposal studies, the TVA/EPA Comparative
Economics of S02 Control Processes, and the EPA Surveys of Utility and Industrial
Boiler FGD Systems, conducted by PEDCo Environmental.
Application of FGD for control of fossil-fuel fired utility and industrial boilers
has increased dramatically during the 1970's in response to the Clean Air Act and
its amendments and the rapidly escalating price of fuel oil. The operating, under
construction, and currently planned full-scale FGD systems are summarized in table
4.
It is interesting to note that about half of the tabulated utility units are in
the planned category, while only about 7% of the total industrial boiler systems are
in this category. This probably indicates that it is more difficult to accurately
determine future plans for these smaller industrial boiler systems than for utility
systems.
A recent report (Ando and Laseke, 1977) estimates that in Japan there were
about 500 FGD plants, equivalent to about 28,000 MW in total capacity in
operation at the end of 1977. About half of the gas processed was reported to be
from utility boilers and the other half from industrial boilers and other sources.
TABLE 4
Summary of U.S. FGD systems
Status
Utility
Industrial Boiler
Operational
Under Construction
Planned
No. of
Units
31*
38
62
Capacity
MW
10,550*
15,664
29,465
No. of Capacity
Units 103 acfmt
34
5
3
5,232
1,636
788
MW,
Equivalent
1,635
511
247
Totals
131
55,679
42
7,656
2,393
Includes two utility prototype systems
f3200 acfm (actual cubic feet/min) = 1 MW
Sources: (Laseke, 1978; Tuttle et al., 1978)
266
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MAIN CONCERNS
EROSION AND CORROSION
INDICES OF DEPENDABILITY
The main concerns about use of FGD are its dependability and costs. As with
any other new technology, operating problems have become evident due both to
design and manner of operation. As experience in design and operation has been
gained, dependability of the systems has improved. Costs of FGD are considered
high by some; however, it is obvious that cost is a relative parameter. It is estimated
that the cost of operation of an FGD system at an electric utility plant may raise
the cost of electric power generated by 10% to 20%. Whether this is reasonable and
worthwhile can only be measured against the health benefits to our population.
Since initial operation of FGD systems, many of the problems that have been
encountered have been eliminated or greatly alleviated. These include chemical
scaling or deposition of solids on the scrubber internals, physical deposition of solids
or plugging, corrosion and/or erosion of the scrubber components, and waste
disposal. Scaling and plugging have been particularly troublesome in the scrubber
mist eliminators. Corrosion/erosion and scaling have been primary problems,
attacking in-line steam tube reheaters.
Control of process chemistry has been the major tool in eliminating scaling
problems. In lime/limestone systems, gypsum scaling is a major concern. By
maintaining the system liquors at a low level of supersaturation or actually
subsaturated with respect to gypsum (see discussion of the Shawnee and LG&E
programs), scaling is generally controlled.
Erosion and corrosion are generally reduced by intelligent selection of materials
of construction. Due to the acidic conditions present in certain areas of the system,
carbon steel is not well suited. Many scrubber manufacturers specify various stainless
steel alloys or are lining their vessels with rubber, polyester, epoxy and other
polymer materials. In addition it has been found that fly ash collected in wet
scrubbing systems contributes to erosion/corrosion of the systems; therefore
collection of fly ash upstream of the S02 scrubber will also alleviate this problem.
In addition to solving scrubber operating problems directly, vendors and users
frequently specify a certain amount of equipment redundancy or spare capacity as a
method of dealing with problems. Thus if a problem occurs, the operator can shut
down the troublesome component, and continue operating on the standby
component. This concept can be applied to small individual components such as
instruments or pumps or to entire subsystems such as scrubber modules. For
example, a 500-MW scrubber system designed with one-third redundancy might
consist of four equal 167-MW scrubber modules.
Many parameters can be defined and calculated as indices of a system's
dependability and each is probably suited to a slightly different viewpoint. Four
such indices are discussed in the EPA Utility FGD Survey reports (Laseke, 1978)
and are defined below:
AVAILABILITY IMPROVED
Availability
Operability
Reliability
Utilization
Hours the FGD system is available for operation
Hours in the period
Hours the FGD system was operated
Boiler operating hours in the period
Hours the FGD system operated
Hours it was called upon to operate
Hours the FGD system was operated
Hours in the period
The dependability of FGD systems for which data were available is plotted as
a function of startup date in figure 4. There is considerable scatter in the data;
however, a correlation coefficient for the least-squares linear plot indicates that the
plot is statistically significant (Laseke and Devitt, 1977). The graph indicates a
general trend of improved dependability of FGD systems as experience is gained.
Specific data points indicate that availability or operability (either is plotted as data
267
-------
tf> Q
H-
z <
< -I
y 100
90
T DC
80
70
60
50
40
.30.
20
10
0
I
I
1972 1973 1974 1975
PLANT START UP DATE
1976
FIGURE 4--Cumulative FGD system dependability (expressed in terms of operability or
availability factors) versus plant startup date
Source: (Laseke and Devitt, 1977)
COSTS
are available) improved from about 30% in 1972 to about 90% for some of the
units started up in 1976.
So many factors affect the costs of installing (capital cost) and operating
(annualized operating cost) FGD systems that it is difficult to arrive at a single
accepted set of figures. Some of the factors affecting capital costs are type of
system, design efficiency, materials of construction, process variation, extent of
redundancy, site specific requirements, new or retrofit, size of system, and method
of disposal of wastes. Likewise, some factors affecting annualized operating costs are
interest charges on the capital cost of the system, fuel sulfur content, removal
efficiency, cost of labor, cost of reagents, by-product credit, hours of operation of
the boiler, and life expectancy of the system.
In the electric utility industry, capital costs are expressed in cost per unit of
plant capacity (S/kW) and annualized operating costs are expresssed in cost per unit
of energy output (mills/kWhr), so that plants can be compared on the same basis.
The annualized operating cost can be viewed as the additional cost of production of
a kilowatt-hour of 'energy attributable to the FGD system. It includes capital cost
by amortizing the initial investment for the FGD plant over the expected life of the
plant and allocating a portion of this cost to each unit of energy output.
Two basic approaches may be taken in an attempt to project FGD costs: (1)
use actual costs for systems already operating, and (2) use engineering design and
cost estimating techniques (based to some extent on experience) to arrive at
generalized costs based on given sets of conditions.
The EPA Utility FGD Survey (Laseke, 1978) reports costs for 20 operating
utility systems (one system was dropped as unreasonably low in cost). These costs
are reported as submitted by the utilities and thus are not on a common basis (e.g.,
some operating costs do not include amortization of capital; others may include
system modification costs). In addition, the reported costs are generally given for
the years in which the plants were constructed, and thus do not take into account
rising construction costs. A summary of these reported costs by system type, with
ranges and averages, is given in table 5.
268
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TABLE 5
Reported costs of operating utility FGD systems
System Type
(Number Reported)
Size, MW*
Range Avg
Capital Cost,
$/kW
Range Avg
Operating Cost,
mills/kWhr
Range Avg
Limestone (7)
Lime (7)
Fly Ash Alkali (2)
Soda Ash (1)
Wellman Lord/Allied (1)
MgOt (1)
115-1420
64-1650
450-720
250
115
108
559
468
585
250
115
108
23-102
38-151
71-84
44
129
137
60.9
82.5
77.5
44
129
137
0.3-2.2
2.0-5.9
0.26
—
8.1
4.7
1.21
4.78
0.26
—
8.1
4.7
*Separate FGD systems located at the same plant are reported combined.
fFigures for size and capital cost are adjusted. The operating MgO system reported
is controlling 108 MW of flue gas from a 316 MW boiler. The remainder of the flue
gas is scrubbed for particulate matter only.
TABLE 6
TVA projected capital and annualized operating costs*
System Type
Limestone
Lime
MgO
Wellman Lord/Allied
*Basis:
Capital Cost, Annualized Operating
Size, MW $/kW Cost, Mills/kWhr
200
500
1000
200
500
1000
200
500
1000
200
500
1000
88.4
68.4
51.4
79.9
61.1
44.9
95.6
71.7
53.0
112.0
84.8
64.2
4.20
3.41
2.74
4.54
3.65
2.94
5.03
4.02
3.26
6.60
5.37
4.46
1. New coal-fired power plant, 3.5% S coal, midwest plant location.
2. Average cost basis 1977. Construction 1975-1978.
3. Minimum process storage and only pumps spared.
4. Working capital is included in total investment.
5. For throwaway systems, sludge disposal in on-site clay lined pond.
6. 30-year plant life, 7000 hr/year operation.
7. Byproduct credit and sludge fixation costs excluded.
8. 90% SO2 removal.
269
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COSTS COMPARISON
FGD COST INCREASES
CONSERVATIVE ESTIMATE
Generalized costs for most of the FGD systems now in use have been
projected by TVA (McGlamery et al., 1976), using a given set of assumptions.
Several of these projected costs are given in table 6 for comparison with reported
actual costs; however, due to the many factors that affect costs and the
non-common basis, perfect agreement should not be expected. Nevertheless, the
average reported capital cost for operating limestone systems (559 MW average
capacity) is only 11% lower than the TVA generalized cost for a 500 MW unit. The
annualized cost, however, is off by a factor of about 3, possibly due to the fact
that some of the reported systems do not include amortization of capital and
working capital which may account for more than half of the annualized cost. For
the lime systems, the average reported actual cost (468 MW average capacity) is 35%
higher than the TVA estimate for a generalized 500 MW lime system, and the
average reported annualized operating cost is 31% higher than the generalized cost.
It should be noted that the TVA costs are all for new systems, while the reported
actual costs average new and retrofit systems.
Based on a cost for generation of electric power of 3
-------
generating capacity is coal-fired, it can be concluded that coal-fired power plants will
produce about the same or a somewhat greater proportion of our electric power by
the end of the century. All of this indicates a growing need for FGD.
Based on the EPA Utility FGD Survey (Laseke, 1978), taking into account
specific known FGD systems in operation now, currently under construction, and
those in various stages of planning, we can project about 56,000 MW of generating
capacity being controlled by FGD systems by 1986. (See table 4.) As previously
mentioned, there was at the end of 1977 about 10,000 MW of FGD controlled
utility generating capacity.
NON-UTILITY BOILER
APPLICATION
It is more difficult to project the non-utility boiler FGD applications since
plans for construction are not announced as far in advance. In addition, many
industrial boilers in operation and planned are too small to be covered by present
federal and state NSPS.
With utility boilers, however, assuming an annual growth rate of 5.5% for
coal-fired boilers through 1990 and further assuming that with revised NSPS (1978
revision), all new coal fired boilers will be controlled by FGD after 1983, the
projected applications of FGD are 87,000 MW of control by 1985 and about
176,000 MW by 1995.
POWER PLANT
FGD CONTROL
In October/November 1973, national public hearings on power plant
compliance with sulfur oxide air pollution regulations were held in Washington, D.C.
As a result of those hearings, EPA concluded there would be a need for 66,000 MW
of power plant FGD control by the end of 1975, 73,000 MW by the end of 1977,
and 90,000 MW by the end of 1980 (EPA, 1974) in order to meet NSPS and the
other requirements of State Implementation Plans to achieve NAAQS. These figures
assumed use of some low-sulfur coal and some redistribution of low-sulfur coal
supplies.
Figure 5 shows a plot of the growth of utility FGD application between 1968
and 1977, together with projections for known currently planned FGD applications
and projected application of FGD, assuming all coal-fired boilers would be controlled
after 1983. Also shown in figure 5 is the projected need for FGD expressed in the
1973 national public hearings. The plot shows that we now fall short of the 1973
projected requirements and will probably continue falling short unless application of
FGD increases dramatically as is the case in the projection, assuming that all new
coal-fired power plants be controlled by FGD after 1983. This projection would be
reasonable with revised new source performance standards requiring 85%-90% S02
removal.
The projected increase in the use of high sulfur coal in the coming years will
be accompanied by a corresponding increase in the emissions of sulfur oxides.
Because of the limitations of the low sulfur coal and coal cleaning options,
application of FGD technology is playing a critical control role since it provides the
leading near-term option presently available for quickly reducing sulfur oxide
emissions in compliance with the Clean Air Act Amendments.
ATTRACTIVE ALTERNATIVES
Several important emerging technologies including fluidized bed combustion
will offer attractive alternatives to the use of FGD but will probably not make
significant commercial impact prior to 1985.
The Federal Interagency FGD program in conjunction with the private sector
has been instrumental in furthering the development, demonstration, and application
of FGD technology. Utility application of FGD systems presently includes over
55,000 MW of capacity either in operation, under construction, or planned.
Although some technical problems still persist at certain installations, the general
dependability of FGD systems has steadily improved during the past several years as
the technology has matured.
271
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90
80
70
60
50
40
30
20
1973 PROJECTED NEED
FOR FGD TO MEET SIP'S
AND NSPS
PROJECTED GROWTH, FGD
FOR ALL NEW COAL UNITS
AFTER 1983
PROJECTED GROWTH
FROM KNOWN PLANNED AND
CURRENTLY CONSTRUCTED
UNITS
CURRENTLY OPERATING
FGD
1970 1975 1980 1985
END OF CALENDAR YEAR
1990
FIGURE 5—Utility FGD, present application, projected growth, and need
Sources: (Laseke, 1978 and EPA, 1974)
272
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References
Ando, J. and B. A. Laseke. September 1977, "SO2 Abatement for Stationary
Sources in Japan," Report No. EPA-600/7-77-103a (NTIS No. PB 272986/AS), pp.
3-2.
EPA, January 1974, "Report of the Hearing Panel National Public Hearings on
Power Plant Compliance with Sulfur Oxide Air Pollution Regulations," conducted
10/18/73 11/2/73 by U.S. EPA. Submitted to the Administrator, U.S. EPA by
members of the hearing panel.
EPA, December 1977, "National Air Quality and Emissions Trends Report, 1976,"
Report No. EPA-450/1 -77-002 (NTIS No. PB 279007).
Gilleland, J. E. February 1978, "Electric Energy Supply into 21st Century:
Challenges and Changes" in "Journal of the Power Division Proceedings of the
American Society of Civil Engineers," Vol. 104 No. P01.
Laseke, B. A. March 1978, "EPA Utility FGD Survey: December 1977 January
1978," Report No. EPA-600/7-78-051a (NTIS No. PB 279011/AS).
Laseke, B. A. and T. W. Devitt. March 1978, "Status of Flue Gas Desulfurization
Systems in the United States," in Proceedings: Symposium on Flue Gas
Desulfurization -- Hollywood, FL, November 1977, Volume I, Report No.
EPA-600/7-78-058a.
McGlamery, G. G., H. L. Faucett, R. L. Torstrick, and L. J. Henson. May 1976,
"Flue Gas Desulfurization Economics," in Proceedings: Symposium on Flue Gas
Desulfurization, New Orleans, March 1976, Volume I, Report No. EPA-600/
2-76-136a (NTIS No. PB 255317/AS), pp. 84-85.
Ness, H. M., E. A. Sondreal, F. Y. Murad, and K. S. Vig. July 1977, "Flue Gas
Desulfurization Using Fly Ash Alkali Derived from Western Coals," Report No.
EPA-600/7-77-075 (NTIS No. PB 270572/ASK
Patel, V. P. and L. Gibbs. March 1978, "Effects of Alternative New Source
Performance Standards on Flue Gas Desulfurization System Supply and Demand,"
Report No. EPA-600/7-78-033 (NTIS No. PB 279080/AS), pp. 2-2.
Ponder, W. H., R. D. Stern, and G. G. McGlamery. August 3-5, 1976, "S02 Control
Technologies Commercial Availabilities and Economics," presented at 3rd Annual
International Conference on Coal Gasification and Liquefaction: What Needs to be
Done Now?, Pittsburgh, Pennsylvania.
Richards, C. L. April 1978, "Conversion to Coal Fact or Fiction," Combustion,
pp. 7-13.
Slack, A. V. and G. A. Hollinden. 1975, "Sulfur Dioxide Removal from Waste
Gases," 2nd Ed., p. 137, Noyes Data Corporation, Park Ridge, New Jersey.
273
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Tuttle, J., A. Patkar, and N. Gregory. March 1978, "EPA Industrial Boiler FGD
Survey: First Quarter 1978," Report No. EPA-600/7-78-052a (IMTIS No. PB
279214/AS).
Van Ness, R. P., R. C. Somers, T. Frank, J. M. Lysaght, I. L. Jashnani, R. R. Lunt,
and C. R. LaMantia. January 1978, "Project Manual for Full-Scale Dual Alkali
Demonstration at Louisville Gas & Electric Company Preliminary Design and Cost
Estimate," Report No. EPA-600/7-78-010 (NTIS No. PB 278722/AS).
Williams, J. E. April 1977, "Summary of Operation and Testing at the Shawnee
Prototype Lime/Limestone Test Facility" EPA, IERL-RTP Highlight Report, Report
No. IERL-RTP-P-035.
274
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DISPOSAL OF POWER PLANT WASTES
Julian W. Jones
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
SOLID WASTE GENERATION
COAL ASH PRODUCTION
GYPSUM PRODUCTION
Modern fossil-fueled, steam-electric generating plants present the full spectrum
of potential environmental problems—pollution of air and water and the generation
of large quantities of solid waste. Essentially all of the solid wastes, excluding
bottom ash, are generated by the use of air pollution control devices—mechanical
collectors (e.g., cyclones), electrostatic precipitators, baghouses, and scrubbers—to
control emissions of fly ash and sulfur dioxide (SC^). Although there are other
wastes, such as those from water treatment systems, the quantities of these are small
•compared with the large amounts of ash and SC>2 scrubber waste produced.
Coal ash production by electric utilities is expected to reach 65 million metric
tons/yr, including over 45 million metric tons/yr of fly ash, by 1980(1). U.S.
electric utility commitments to SO2 scrubbers, or flue gas desulfurization (FGD)
systems, currently total over 55,000 MW of electrical generating capacity(2).
Assuming that all of these plants will burn a typical high sulfur eastern coal and use
a limestone scrubbing FGD system, approximately 29 million metric tons/yr (dry) of
FGD waste, exclusive of fly ash, will be produced by the mid-1980's, when all of
these plants are onstream.
Extensive utilization of coal ash is both technically and economically feasible.
For example, fly ash can be admixed with Portland cement clinker to as high as a
1:5 ratio (ash:clinker). With Portland cement production in the U.S. currently
around the 80 million ton/yr mark, this means that approximately one-third of the
1980 fly ash production could be used for this single application. However, current
utilization of fly ash for all applications is just over 13 percent of production,
according to the National Ash Association(3).
In Japan, over a million metric tons of gypsum were produced, primarily for
use in wallboard and Portland cement, by FGD processes in 1975(4). TVA has
recently completed a study for EPA which indicates that approximately two-thirds
of the gypsum requirements for the Portland cement industry in the U.S. could be
supplied by FGD systems in a competitive marketCo). However, this use would
consume only about 10 percent of the FGD waste expected to be produced in the
mid-1980's. On the other hand, a shift to grass-roots wallboard plants near power
plants (instead of near natural gypsum delivery points) could increase this low
275
-------
percentage substantially. The wallboard industry currently consumes about 11 million
metric tons of gypsum annually, almost 4 times the portland cement industry's
annual consumption(5).
In any event, because of the current lack of market demand for most of the
coal ash and FGD wastes, most electric utilities find that disposal of these wastes is
the most attractive choice. However, once the decision is made in favor of disposal,
the environmental and economic effects of the various disposal options have to be
addressed.
COAL ASH DISPOSAL
Disposal of coal ash, either in ponds or landfills, has been practiced for many
years. Ash ponds at power plants overflow to watercourses in numerous locations.
Until recently, such practice was not of major environmental concern, very likely
because the major chemical constituents of fly ash (i.e., those comprising the
greatest percentage by weight) have a very low solubility. However, both existing
and pending regulations on plant discharges and disposal of wastes on the land have
caused a trend towards (1) dry ash handling and disposal in a landfill, (2)
co-disposal of ash with FGD waste (either in a zero-discharge pond, with recycle of
water to the plant, or as part of a FGD waste treatment process), or (3) a
zero-discharge pond, with recycle of water to the plant.
Because of these concerns, considerable research and development was
undertaken by governmental and private organizations. Results of these efforts are a
greater understanding of the nature of FGD wastes, and a trend toward more
environmentally acceptable and cost-effective methods for disposal, either 1) in
ponds which are lined with clay or other low permeability material (to reduce the
potential for water pollution) or 2) in a landfill, usually after chemical treatment of
the waste to improve its physical stability and reduce its permeability.
Initially, FGD waste was disposed of in ponds, usually along with fly ash from
the plant. However, since FGD systems have been in the limelight since early in the
period of U.S. environmental awareness, very early in their commercial history there
was concern about disposal of wastes from these systems because (1) the large
amount of occluded water in the wastes or sludges made them physically unstable,
(2) the quite variable physical and chemical properties of the wastes caused them to
be an unknown material, and (3) the soluble and slightly soluble chemical
constituents in the wastes caused them to be potential sources of water pollution.
COAL MINE RECLAMATION
Other methods of coal ash and FGD waste disposal are currently being
considered, including the return of these wastes for use in coal mine reclamation. At
least two plants, in North Dakota and Texas, are already disposing of the wastes in
this manner. Disposal in the ocean, possibly by construction of an artificial reef of
treated blocks of FGD waste and fly ash, is also being studied; the environmental
acceptability of this method has not yet been demonstrated.
Federal legislation which applies to the handling and disposal of coal ash and
FGD waste in ponds, landfills, coal mines, and the ocean is shown in table 1. The
two most significant legislative acts (i.e., acts which have the greatest impact on
disposal of these wastes) are 1) the Federal Water Pollution Control Act (FWPCA)
Amendments of 1972 and 2) the Resource Conservation and Recovery Act (RCRA)
of 1976.
FWPCA REQUIREMENTS
The FWPCA established a program whereby all discharges to navigable waters
require a permit, issued by EPA or a state delegated the authority by EPA. The Act
also required industries to use the best practicable control technology currently
available (BPCTCA) to control pollutant discharges by July 1, 1977 and requires
application of best available technology economically achievable (BATEA) by July 1,
1983.* EPA has established national effluent guidelines (based on BPCTCA and
*The FWPCA Amendments of 1977 made the effective date for BATEA a
variable, depending on the chemical(s) being controlled.
276
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TABLE 1
Federal regulatory framework for disposal of coal ash and FGD waste
Possible Environmental
Impact
Legislation
Administrator
Surface Water
Contamination
Federal Water Pollution
Control Act Amendments
of 1972
Environmental
Protection Agency
Groundwater
Contamination
• Resource Conservation
and Recovery Act of
1976
• Safe Drinking Water
Act of 1974
• Environmental
Protection Agency
• Environmental
Protection Agency
Waste Stability/
Consolidation
• Dam Safety Act of
1972
• Surface Mining Control
and Reclamation Act
of 1977
• Occupational Safety and
Health Act of 1970
Federal Coal Mine Health
and Safety Act of 1969
• Army Corps
of Engineers
• Office of
Surface Mining
Reclamation and
Enforcement
• Occupational
Safety and
Health Administration
• Mining Enforcement
Safety Administration
Fugitive Air
Emissions
Clean Air Act
Hazardous Materials
Transportation Act of 1975
Federal Coal Mine Health
and Safety Act of 1969
Occupational Safety and
Health Act of 1970
Environmental
Protection Agency
Department of
Transportation
Mining Enforcement
Safety Administration
Occupational Safety
and Health Administration
Contamination of
Marine Environment
Marine Protection Research
and Sanctuaries Act of 1972
• Environmental
Protection Agency
BATEA) for existing power plants, as well as New Source Performance Standards
(NSPS) for plants for which construction was initiated after the regulations were
proposed.
EFFLUENT GUIDELINES
A summary of effluent guidelines and standards for steam-electric power plant
ash ponds is given in table 2. The discharge requirements for total suspended solids
(TSS) from fly ash ponds in many cases require control of lightweight cenospheres
(floaters). In addition, a number of existing plants have to treat ash pond overflow
to meet the pH requirement because most fly ashes are alkaline. (In some cases pH
in an ash pond discharge can be 10 or above.) Reducing the pH by adding acid not
only may be expensive, but also could result in an increase in certain trace metal
concentrations. (Bottom ash ponds, on the other hand, typically have a relatively
neutral pH, lower trace metals, and solids which settle more easily than fly ash.)
277
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TABLE 2
Effluent guidelines and standards for power plant ash ponds
Discharge Stream
All Plant Discharges
Bottom Ash
Transport Water
Fly Ash
Transport Water
Controlled Parameter BPCTCAt
pH
Polychlorinated
biphenyls (PCBs)
total suspended
solids (TSS)
oil and grease
TSS
oil and grease
6.0-9.0
zero
30-day daily
average maximum
30 100
15 20
30 100
15 20
BATEAt
6.0-9.0
zero
30-day
average
3CH-12.5t
15-M2.5
30
15
daily
maximum
100-M2.5
20-M2.5
100
20
NSPSt
6.0-9.0
zero
30-day daily
average maximum
30^20 100^-20
15-^20 20^20
zero zero
zero zero
fAII quantities except pH are in units of mg/1.
J-r12.5 or -^20 indicates the required degree of recycle (or number of cycles) of water;
-H2.5 means 8% blowdown allowed, while ^-20 means 5% blowdown allowed.
ACHIEVING
ZERO DISCHARGE
Achieving zero discharge requires either complete recycle of water used to
sluice fly ash to the pond or dry fly ash collection and disposal in a landfill. Dry
collection and landfill disposal of fly ash is current practice. However, few fly ash
ponds are operated with complete recycle of sluice water; possible operational
problems caused by an increase in soluble constituents in the sluice water, for the
most part, have been examined only theoretically.
Note that no guidelines or standards have been promulgated specifically for
FGD systems (although the limitations for low volume waste streams are currently
being applied). In general, it is assumed that there will be no direct discharge from
these systems. However, because of operational problems which required extra water,
some of the commercial FGD systems have required a discharge. Nevertheless, these
systems were designed to operate closed-loop; i.e., with the only discharge of water
being that associated with the FGD waste. In the more recent systems to come on
line, this design feature is an operational fact.
MAJOR ENVIRONMENTAL
CONCERN
With no direct discharge from FGD systems taking place, the major
environmental concern associated with FGD waste disposal is the potential
contamination of groundwater. This can also be said for an ash pond with no
discharge, or disposal of ash in a landfill. The major federal legislation which
addresses these potential problems in the RCRA.
Before enactment of the RCRA, there was no comprehensive federal authority
to regulate disposal of wastes. This Act is designed to eliminate improper disposal of
wastes by federally regulated disposal of hazardous waste§ and by state regulated
(with federal assistance) disposal of nonhazardous solid waste. The Act defines a
hazardous waste as a waste which poses a "substantial present or potential hazard to
human health or the environment" if improperly managed.
278
§EPA may authorize state agencies to implement their own programs if they
are deemed equivalent to EPA regulations for hazardous waste disposal.
-------
CRADLE TO GRAVE
CONTROL
The regulatory philosophy in the RCRA for hazardous waste is cradle to grave
control. A manifest system will be used to track the movement of hazardous waste
from the point of generation through transportation, treatment, and storage, to
disposal, whether any of these steps are on- or off-site. Detailed requirements for
hazardous waste disposal sites will be established by EPA. In addition, criteria and
test methods to identify hazardous wastes will be established; a list of wastes known
a priori to meet the criteria will be included in the regulations.
Although the RCRA called for promulgation of hazardous waste regulations by
April 1978, they have been delayed. However, draft regulations have been prepared
and are currently under review. The criteria for identifying hazardous wastes include
characteristics such as flammability, corrosiveness, infectiousness, reactivity (e.g.,
strong oxidizing agents), radioactivity, and toxicity. The protocol for toxicity
includes subjecting the waste to a toxicant extraction procedure (TEP), followed by
a series of chemical or biological tests, including a test for bioaccumulation
potential.
Currently, neither coal ash nor FGD waste has been declared a hazardous
waste under the draft. RCRA regulations. However, both fly ash and FGD waste are
suspect because of the levels of certain trace elements in them. Nevertheless, testing
(using the toxicity protocol) will be necessary before even a preliminary judgement
can be made. It is clear, though, that, if any power plant waste is determined to be
hazardous, it will be subject to a much more stringent set of regulations than
nonhazardous waste.
STATE REGULATION
Nonhazardous solid waste will be regulated through individual state plans, the
major point of which will likely be (according to RCRA) the elimination of open
dumps; i.e., sanitary landfills must be used. Although protection of the environment
must be a major consideration in the state plans, the implementation and
enforcement of any regulation of disposal of nonhazardous wastes will be up to the
state. The RCRA does not provide for federal enforcement of state regulations.
As shown previously, the FWPCA Amendments of 1972, the Safe Drinking
Water Act of 1974, and the RCRA created the framework for the regulations which
would eliminate or minimize chemical pollutant discharges into surface waters and
groundwaters. Recognizing the need for better definition of approaches to meet the
desire of this legislation, EPA in 1972 initiated a major program of research and
development (R&D) in the area of FGD waste disposal. The primary objectives of
this program were to better quantify any potential environmental problems
associated with FGD waste disposal and to assess FGD waste disposal technologies.
(Note that coal ash disposal alone was not investigated under this initial program.
However, since FGD waste in most instances either contains fly ash—collected in the
scrubber—or is mixed with ash prior to disposal, any thorough study of FGD
waste—such as was conducted under this program—includes a study of fly ash.
Because of this rather inseparable relationship between FGD waste and fly ash, the
term flue gas cleaning [FGC] wastes was coined to cover both wastes. This term
will be used in the remainder of this paper.)
WASTE AND WATER
PROGRAM
In late 1974, plans were formulated to greatly expand EPA's FGC
waste-related R&D efforts as part of the Energy/Environment R&D Program. These
efforts included continuing improved quantification of potential environmental
problems (of the 1972 program). They were also aimed at reducing costs,
investigating a broader range of alternative waste disposal options, examining possible
uses of the wastes. The Energy/Environment R&D Program involving disposal of
power plant wastes is part of a larger program which involves control of waste and
water pollution. The Waste and Water Program, as the larger program is known, is
divided into three major areas:
• FGC Waste Disposal.
• FGC Waste Utilization.
• Water Utilization/Treatment.
279
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FGC CHEMICAL
CHARACTERISTICS
Each of these program areas includes a number of projects; these are listed in table
3. The FGC Waste Disposal area of the Waste and Water Program consists of 17
projects, 5 of which are recently completed. The discussion which immediately
follows describes some of the significant accomplishments of these projects.
The chemical characteristics of FGC scrubber waste, to a large degree, have
been quantified. FGC waste liquors have been shown to exceed drinking water
standards for total dissolved solids (TDS), with high concentrations of calcium,
sulfate, and chloride (and, in some cases, magnesium and sodium). In addition,
concentrations of several trace metals have been noted in excess of drinking water
standards. The chemical composition of FGC waste solids consists of calcium sulfite
hemihydrate, calcium sulfate dihydrate (gypsum) and/or hemihydrate, and calcium
carbonate, plus any fly ash collected in the scrubber. The percentage of each solid
constituent is primarily a function of the alkaline additive (e.g., lime, limestone), the
percent sulfur in the coal, and the manner in which the scrubber system is operated
(e.g., whether forced oxidation is applied, whether fly ash is collected separately).
Although fly ash has been shown to be a major contributor of trace elements to the
TABLE 3
Projects in the waste and water program
Project Title
Contractor/Agency
FGC WASTE DISPOSAL
Assessment of Technology for Control
of Waste and Water Pollution
§FGC Waste Characterization, Disposal
Evaluation, and Transfer of FGC Waste
Disposal Technology
§-**Solid Waste Impact of Controlling S02
Emissions from Coal-Fired Steam
Generators
Lab and Field Evaluation of 1st and 2nd
Generation FGC Waste Treatment Processes
Ash Characterization and Disposal
§Studies of Attenuation of FGC Waste
Leachate by Soils
§ Establishment of Data Base for FGC
Waste Disposal Standards Development
Development of Toxics Speciation Model
and Economic Development Document for
FGC Waste Disposal
Shawnee FGC Waste Disposal Field
Evaluation
Louisville Gas and Electric Evaluation
of FGC Waste Disposal Options
FGC Waste Leachate-Liner Compatibility
Studies
Lime/Limestone Wet Scrubbing Waste
Characterization and Disposal Site
Revegetation Studies
Arthur D. Little, Inc.
The Aerospace Corporation
The Aerospace Corporation
U.S. Army Corps of Engineers
(Waterways Experiment Station)
Tennessee Valley Authority
U.S. Army Test and Evaluation
Command
(Dugway Proving Ground)
Stearns, Conrad and Schmidt
Consulting Engineers, Inc.
(SCS Engineers)
SCS Engineers
Tennessee Valley Authority
The Aerospace Corporation
Louisville Gas & Electric Co.
(Subcontractor: Combustion
Engineering, Inc.)
U.S. Army Corps of Engineers
(Waterways Experiment Station)
Tennessee Valley Authority
§ Project Completed
**Direct Support of Regulation Development
continued
280
-------
PREFERENTIAL PARTITIONING
FGC PHYSICAL
PROPERTIES
TABLE 3 (continued)
waste solids and liquor, separate collection of fly ash does not necessarily mean that
concentrations of all these elements in the waste liquor will be insignificant (6).
A compilation of existing data on coal ash, generated by TVA and others, was
reported in early 1977 (7). This report showed that a number of potentially
hazardous trace constituents tend to be concentrated in fly ash (as opposed to
bottom ash). Further efforts are currently underway to better define this preferential
partitioning of chemical constituents between fly ash and bottom ash, as well as the
concentration of specific constituents as a function of particle size. This latter
information would be especially significant in understanding the effect of the
presence (or absence) of fly ash on FGD waste liquor composition.
The physical properties of FGC waste have been shown to vary considerably
from system to system; chemical composition is related to, but does not adequately
define, the size and type of the solid crystals. For example, in comparing the lime
and limestone scrubber solids from the EPA/TVA Shawnee test facility, the
Project Title
Contractor/Agency
FGC WASTE DISPOSAL (Continued)
§Development of EPA Pilot Plant Test
Plan to Relate FGC Waste Properties to
Scrubber Operating Variables
Dewatering Principles and Equipment
Design Studies
Conceptual Design/Cost Study of Alter-
native Methods for Lime/Limestone
Scrubbing Waste Disposal
Evaluation of FGC Waste Disposal in
Mines and the Ocean
**Evaluation of Power Plant Wastes for
Toxicity as Defined by RCRA
FGC WASTE UTILIZATION
§Gypsum By-Product Marketing Studies
Pilot Studies of a Process for Recovery
of Sulfur and Calcium Carbonate From
FGC Waste
Fertilizer Production Using Lime/Lime-
stone Scrubbing Wastes
§Use of FGC Waste in a Process for
Alumina Extraction from Low-Grade Ores
WATER UTILIZATION/TREATMENT
Assess Power Plant Water Recycle/Reuse
Pilot Demonstration of Water Recycle/Re-
use
Characterization of Effluents from
Coal-Fired Power Plants
§**Water Pollution Impact of Controlling
S02 Emissions from Coal-Fired Steam
Generators
Radian Corporation
Auburn University
Tennessee Valley Authority
Arthur D. Little, Inc.
Radian Corporation
Department of Energy
(Oak Ridge National Laboratories)
Tennessee Valley Authority
Pullman-Kellogg
Tennessee Valley Authority
TRW, Inc.
Radian Corporation
Contractor Not Yet Selected
Tennessee Valley Authority
Radian Corporation
^Project Completed
*Direct Support of Regulation Development
continued
281
-------
limestone scrubber solids were found to be primarily individual platelets or rosette
aggregates, while the lime scrubber solids were primarily spherical aggregates with
somewhat better settling and dewatering properties. However, the chemical
compositions of the solids from both scrubbers were quite similar to one another.
Regardless of the chemical composition, when FGC wastes are not adequately
dewatered (or are allowed to rewet after dewatering), they tend to be physically
unstable, or fluid, with little or no compressive strength. This physical instability of
FGC wastes and the pollution potential of chemicals dissolved in the occluded water
are the two major environmental concerns associated with disposal of these wastes.
PHYSICAL STABILITY
Several approaches for improving the physical stability of FGC wastes, as part
of a disposal method, have been and continue to be studied. A basic feature of all
approaches is the removal of sufficient water from the waste, either physically or
chemically (or a combination of the two), to achieve physical stability. Occluded
water is more easily removed physically if the solid particles are large enough to
settle rapidly or provide a sufficiently porous structure for mechanical water removal
(e.g., filtration). Difficulty in physical dewatering of FGC wastes is normally
attributed to the small platelet crystalline structure of calcium sulfite. However,
TABLE 3 (concluded)
Project Title
Contractor/Agency
WATER UTILIZATION/TREATMENT (Continued)
Treatment of Power Plant Wastes With
Membrane Technology
Power Plant Cooling Tower Slowdown
Recycle by Vertical Tube Evaporator
With Interface Enhancement
§Treatment of Flue Gas Scrubber Waste
Streams with Vapor Compression Cycle
Evaporation
§Alternatives to Chlorination for
Control of Condenser Tube Biofouling
**Environmental Impact of Alternatives
for Control of Condenser Tube Bio-
fouling
§ Bromine Chloride-An Alternative to
Chlorine for Fouling Control in Con-
denser Cooling Systems
**Evaluation of Lime Precipitation for
Treatment of Boiler Tube Cleaning Waste
§**Assessment of Technology for Control
of Toxic Effluents From the Electric
Utility Industry
§** Field Testing/Lab Studies for Develop-
ment of Effluent Standards for Elec-
tric Utility Industry
Effects of Pathogenic and Toxic Material
Transported Via Cooling Device Drift
Assessment of Measurement Techniques
for Hazardous Pollution From Thermal
Cooling Systems
Tennessee Valley Authority
University of California-
Berkeley
Resources Conservation Company
Monsanto Research Corporation
TRW, Inc.
Martin Marietta Corporation
Hittman Associates, Inc.
Radian Corporation
Radian Corporation
H2M, Inc.
Lockheed Electronics Co.
Northrop Corporation
^Project Completed
*Direct Support of Regulation Development
282
-------
CRYSTAL NUCLEATION
AND GROWTH
OXIDATION TECHNIQUES
OTHER STABILIZATION/
DISPOSAL TECHNIQUES
some forms of calcium sulfite crystals are more easily dewatered than others,
suggesting the possibility of avoiding the less desirable forms by proper scrubber
operation.
Currently, though, the relationship between scrubber operating parameters and
the characteristics of the calcium sulfite crystals has not yet been defined
adequately. However, certain qualitative observations, such as the comparison
between lime and limestone scrubbers mentioned above, have already been made.
For example, in limestone scrubbing systems, there appears to be an inverse
relationship between sulfite crystal size and limestone additive stoichiometry (8). In
addition, in tests with lime at Louisville Gas and Electric's Paddy's Run station,
calcium sulfite crystals formed in a large (high retention time) tank were mostly
individual platelets, while crystals formed in a small (low retention time) tank were
primarily aggregates of platelets (9).
To better define the relationship between scrubber operation and calcium
sulfite crystals, crystal nucleation and growth were studied. This study resulted in a
computer model and a test plan for both completion of the model and defining the
scrubber/crystal relationship (10). The tests will be conducted at the EPA-RTP pilot
plant facilities later this year. Hopefully, the result of this testing will be the
development of procedures for obtaining consistent, easily dewatered calcium sulfite
solids.
A complementary approach to improving the quality of calcium sulfite solids
would be to improve the performance of dewatering equipment. Laboratory
pilot-scale testing using calcium sulfite waste from Louisville Gas and Electric has
shown current commercial gravity settling devices (clarifiers, thickeners) to be far
from optimum. A design approach has been developed whereby the clarification and
thickening functions of the gravity settler have been separated into two pieces of
equipment, each of which can be optimized for its function. The result is improved
dewatering (thicker underflow) and satisfactory clarification (without using
flocculants), with substantially smaller, less expensive equipment. Current plans are
to demonstrate this design approach on a large pilot scale at TVA's Shawnee Steam
Plant near Paducah, Kentucky. Testing should be underway by September or
October 1978. A paper describing the laboratory pilot results will be presented later
this month (11).
One way to avoid the dewatering problems associated with calcium sulfite
crystals in FGC waste is to use oxidation techniques to produce calcium sulfate or
gypsum (CaS04*2H20). Gypsum crystals are typically much larger and thicker than
sulfite crystals; therefore they settle more quickly and trap less water upon settling.
Oxidation of the calcium sulfite outside of the scrubber system, although feasible, is
more expensive; oxidation within the scrubber loop is simpler and less expensive.
This latter approach has been successfully tested at the laboratory and large field
pilot level (12,13); commercial systems are now being offered by experienced
suppliers.
Many utilities are currently choosing chemical treatment (sometimes called
fixation) processes to physically stabilize their FGC waste. Field testing these
processes under the EPA Waste and Water Program has shown that the treated waste
exhibits significant structural improvement, at least a 50 percent reduction in major
solubles (e.g., chloride) in the leachate, and an order of magnitude (or more)
reduction in permeability (14). Another advantage of chemical treatment is that coal
ash can be co-disposed of, along with the FGC waste. A coring rig on one of the
treated waste disposal sites at TVA's Shawnee Steam Plant is shown in figure 1.
Other stabilization/disposal techniques are being evaluated, such as the use of
underdrainage and compacting of untreated FGC wastes, and the production/disposal
of gypsum. A paper describing recent results of th-eir evaluation is being presented
later this month (15). In areas with appreciable rainfall, the underdrainage approach
appears to require dividing the disposal area into several sections, i.e., over the Life
of the plant, the disposal would be accomplished one section at a time. For gypsum
disposal in a pile, considerable maintenance may be required because of surface
cracking from freeze-thaw cycles and/or erosion from rainfall (see figure 2) (15).
283
-------
FIGURE 1— Coring rig on FGC waste disposal test site at TVA's Shawnee steam plant
FIGURE "i—FGC gypsum pile at Shawnee, showing freeze-thaw cracks and erosion
COSTS
Along with the technical/environmental evaluation of alternative FGC waste
disposal techniques, the costs of each technique have also been determined.
Preliminary cost estimates (1977 $) for a typical high-sulfur coal-fired plant will be
reported later this month; these show ponding costs of about $5-8 per metric ton
(dry solids, including fly ash) and chemical treatment/landfill costs of about $10 per
metric ton (same basis as ponding) (16). More detailed cost estimates (in 1980 $),
also recently reported, show ponding costs of about $9 per metric ton and chemical
treatment/landfill costs of about $14 per metric ton (16). (It should be noted that
the $14 figure includes all dewatering equipment; the earlier $10 figure assumed the
clarifier/thickener as part of the scrubber system. In addition, clarifiers were
excluded in both ponding cost estimates.)
284
-------
OTHER EFFORTS
DISPOSAL IN AREA
SURFACE MINE
OCEAN DISPOSAL
The $14 per metric ton cost converts to about 1.5 mills/kWhr revenue
requirement; this compares to a total FGC system revenue requirement of about 5
mills/kWhr. Thus it is clear that the waste disposal costs are a major part of the
FGC system costs and, further, that any significant savings in waste disposal costs
will substantially reduce the total system costs.
A number of the efforts described above (e.g., improving performance of
dewatering equipment) are aimed at a reduction in disposal costs. Other efforts will
be studied in the near future; e.g., using only the minimum quantity of fly ash
required to chemically treat the FGC waste and marketing the excess, or using a
combination of coal washing (for ash and sulfur removal) and FGC.
Another approach to reduce costs is to use disposal methods which avoid the
need for a specially prepared disposal site (e.g., pond). Two methods currently under
study are disposal in coal mines and in the oceans.
Coal-mine disposal of FGC waste has greatly interested engineers in the flue
gas desulfurization industry for many years because of established means of
transportation between the coal mine and the power plant and the need for material
to fill the void left by mining of the coal. In addition, many plants may not have
sufficient land area for on-site disposal. The same reasoning, of course, can be
applied to coal ash alone. Preliminary technical/economic assessments conducted
under the EPA Waste and Water Program indicated that active area surface mines are
the most promising candidates for this disposal approach (17).
FGC waste from the Milton R. Young Station of Minnkota Power Cooperative
near Center, North Dakota, is currently being disposed of in an area surface mine
near the plant. Ash from this plant has been disposed of in the mine for some time.
A 2-year assessment of the environmental effects of this operation is being
conducted by the University of North Dakota and the North Dakota State
Geological Survey, under EPA sponsorship. Preliminary results of this effort are
expected in late 1978. Successful demonstration of this disposal approach could
make conversion to coal quite feasible even in areas where land for disposal is
limited.
Preliminary costs of mine disposal were also determined; a wide range of from
(in 1977 $) about $4 to about $10 per metric ton of dry solids, depending on
treatment (if used) and transportation costs, were reported (17). More detailed costs
of this disposal option are being prepared.
Ocean disposal of FGC waste is also being assessed because many plants in the
northeast may have difficulty switching to coal for lack of disposal sites; however,
many of these plants do have access to the ocean. It was also recognized that the
major soluble chemical constituents in FGC waste are found in relatively high
concentrations in seawater. This assessment has identified several potential
environmental problems, the major one of which is sulfite toxicity. It appears that
these problems could be alleviated by either chemical treatment to a brick-like form
(possibly creating an artificial reef) or oxidation to gypsum (followed by a widely
dispersed disposal operation). Preliminary costs of this approach were estimated to
be from (in 1977 $) about $4 to about $8 (treated) per metric ton of dry solids
for disposal on the Continental Shelf; deep ocean disposal would be expected to add
to these costs another $3 to $4 per metric ton (17). More detailed costs for this
disposal method are being prepared. Pilot disposal simulation studies are underway
to define the environmental effects of both untreated and treated FGC sludge
disposal in the ocean.
As coal becomes the dominant fossil fuel for the generation of electric power,
the environmental, technical, and economic problems associated with the handling
and disposal of FGC wastes are anticipated to increase in prominence. A number of
alternative solutions to these problems exist, but determining the viability of specific
solutions requires consideration of factors that are specific to each plant situation.
For example, an existing power plant with no FGD system may have to choose
between the options of 1) recycling the fly ash sluice water, using side stream
treatment for dissolved salts, or 2) converting to a dry ash handling system so that
285
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WASTE DISPOSAL
FOR SPECIFIC PLANTS
LONG-TERM DATA
NEEDED
ARTIFICAL REEF
CONSTRUCTION
the ash can be used in a local cement plant. The options for specific plants will
vary greatly, depending on things such as applicable regulations; land availability and
cost; water availability, quality, and cost; geology of the plant site; coal
characteristics (percent sulfur, ash, trace elements); and potential markets for wastes.
Obtaining the information required to identify available options and to allow
rational choices to be made is the impetus behind the Energy/Environment R&D
Program in power plant waste disposal. The results of these efforts, already
described, when combined with existing commercial technology, form the bases upon
which the regulations are established. These efforts are continuing; trends in the
Energy/Environment Program as they relate to the regulatory programs, are discussed
here. As previously mentioned, a report has been issued which summarizes and
evaluates existing data on the characteristics of coal ash from studies made by the
Tennessee Valley Authority (TVA) and others (9). TVA is currently characterizing
fly ash as well as evaluating the effect of leachate from ash ponds at two of their
plants. From the TVA efforts under the Energy/Environment Program, as well as
from the efforts by the Electric Power Research Institute (EPRI) (18) and others,
there is a considerable amount of data on coal ash. However, in order to fulfill the
objectives of both the FWPCA and the RCRA, additional information is needed.
Specifically,the behavior of a variety of coal ashes should be studied in closed-cycle
wet sluicing systems. In addition, a variety of FGC wastes, including coal ashes
alone, need to be tested according to the protocol proposed under the RCRA.
Results of testing under the RCRA could have a major effect on the
Energy/Environment Program if a number of FGC wastes are determined to be
hazardous; additional testing of these wastes using the RCRA protocol would
probably be required. A hazardous tag on FGC wastes would also have a significant
effect on the electric utility industry, as well as those industries which currently use
these wastes for construction materials.
The effect which the RCRA will have on the various FGC waste disposal
options which have been applied commercially and other options which continue to
be studied is not yet clear. As described previously, the environmental effects of
various approaches for FGC waste disposal (on land) have generally been evaluated
by determining, as quantitatively as possible, the capability of a particular approach
to minimize or eliminate groundwater and surface water pollution. For example,
leachate generated by the waste in a specific situation was usually compared with
drinking water or other water quality criteria; physical characteristics such as
permeability were measured to determine the quantity of leachate which might be
expected. On this basis, satisfactory disposal approaches would include lined pondstt
or well-managed landfills (of chemically treated waste). This general evaluation
procedure has also been applied to the assessment of disposal in coal mines. All
three of these methods—ponding, landfill, and mine disposal—are currently in
commercial use; mine disposal of FGC waste has only taken place within the. past
year. Long-term data on the environmental effects of these disposal operations are
needed
Another FGC waste disposal option currently being studied is ocean disposal.
If proved to be environmentally acceptable, this option could be used by utilities in
coastal states in which the availability of land for disposal sites is a major problem.
A number of electric utilities in the Northeast have shown great interest in FGC
waste disposal in the ocean. A variation of this option, currently proposed by the
New York State Energy Research and Development Authority (NYSERDA), is
artificial reef construction using large blocks of chemically treated FGC wastes.
Ocean disposal has primarily been studied on a laboratory scale, although some
small-scale field tests have been conducted by the State University of New York at
Stony Brook. The effects on water chemistry as well as on marine life—through
bioassay—are being evaluated. Current EPA ocean disposal regulations are being used
as a benchmark in assessing test results. A considerable amount of testing remains to
be done.
ttTypical ponding operations do not appear to be a desirable ultimate disposal
method because of difficulties in pond reclamation and greater potential (than
landfills) for groundwater contamination.
286
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ESTIMATE OF COSTS
CONCLUSIONS
As environmentally acceptable FGC waste disposal options emerge, a
reasonably accurate estimate of their costs must be determined; costs relative to
alternative options are particularly significant. Costs of all the options just discussed
have been, or are currently being, estimated. TVA is conducting detailed conceptual
design/cost studies of a number of on-land disposal alternatives. As technological
improvements occur, or as disposal options emerge which appear to be more
economically attractive, this cost data base will need to be expanded. In addition,
the effects of pending RCRA regulations will need to be determined.
Improvements to FGC waste disposal technology to reduce costs so far have
primarily concentrated on FGD scrubber system modifications to 1) improve alkali
(e.g., limestone) feed utilization, and 2) reduce FGC waste volume by forced
oxidation to calcium sulfate or gypsum. Studies are underway to evaluate both the
environmental effects and the costs of gypsum disposal. Other cost reduction efforts
have been directed at 1) defining FGD system operating parameters which will result
in reasonably consistent, easily dewatered calcium sulfite solids, and 2) improving
the performance of equipment for dewatering FGC wastes high in calcium sulfite.
The first of these efforts will require a better understanding of nucleation and
growth of calcium sulfite crystals in scrubber systems, a difficult task. The second
effort is based on laboratory pilot studies which have shown the feasibility of major
improvements over commercial designs, including a greater degree of dewatering at
lower cost. However, field pilot studies are required before the concepts can be
utilized commercially. One of the problems the field tests will address is the
capability of the equipment to satisfactorily operate when variations occur in the
waste properties.
A major effort in the Energy/Environment Program is underway to characterize
solid wastes from power plants and to develop technology to minimize the potential
adverse environmental impacts of these wastes. The program has achieved significant
results in a number of areas.
Flue gas cleaning (FGC) wastes have been characterized physically and
chemically; a variety of disposal options have been identified, including detailed
costs associated with these options. Disposal of these wastes in coal mines is
economically attractive and, therefore, is being investigated through lab and field
tests. Methods for achieving major cost reductions in FGC waste disposal have also
been identified and are making their way into the process supply market; these
include oxidation to gypsum and improved dewatering equipment.
Results of these efforts are providing a technical data base for the regulation
of the disposal of power plant wastes.
287
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References
1. Faber, J.H. National Ash Association, "U.S. Overview of Ash Production and
Utilization," in Proceedings: Fourth International Ash Utilization Symposium,
St. Louis, MO, March 24, 25, 1976, MERC/SP-76/4.
2. Laseke, B.A., Jr. PEDCo Environmental, Inc., EPA Utility FGD Survey:
December 1977 January 1978, EPA-600/7-78-051a (NTIS No. 279011/AS),
March 1978.
3. National Ash Association, "Ash At Work," Volume IX, No. 3, 1977.
4. Ando, J., Chuo University, Tokyo. "Status of Flue Gas Desulfurization and
Simultaneous Removal of S02 and NOX in Japan," in Proceedings: Symposium
on Flue Gas Desulfurization, New Orleans, March 1976, Volume I,
EPA-600/2-76-136a (NTIS No. PB 255-317/AS), May 1976.
5. Bucy, J.I. and J.M. Ransom. Tennessee Valley Authority, "Potential Markets
for Sulfur Dioxide Abatement Products," in Proceedings: Symposium on Flue
Gas Desulfurization, Hollywood, FL, November 1977, Volume II,
EPA-600/7-78-058b, March 1978.
6. Leo, P.P. and Jt Rossoff. The Aerospace Corporation, Control of Waste and
Water Pollution from Power Plants: Second R&D Report, draft report to be
published, prepared under EPA Contract 68-02-1010.
7. Ray, S.S, and F.G. Parker. Tennessee Valley Authority, Characterization of
Ash from Coal-Fired Power Plants, EPA-600/7-77-010 (NTIS No. PB
265374/AS), January 1977.
8. Crowe, J.L. and S.K. Seale. Tennessee Valley Authority, Lime/Limestone
Scrubbing Sludge Characterization-Shawnee Test Facility, EPA-600/7-77-123,
October 1977.
9. Hargrove, O.W. and G.P. Behrens. Radian Corporation, Results of FGD System
Testing at Louisville Gas & Electric's Paddy's Run Station, draft report to be
published, prepared under EPA Contract 68-02-2102.
10. Phillips, J.L., et al. Radian Corporation, Development of a Mathematical Basis
for Relating Sludge Properties to FGD-Scrubber Operating Variables.
EPA-600/7-78-072, April 1978.
288
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11. Tarrer, A.R., et al. Auburn University, "Dewatering of Flue Gas Cleaning
Waste by Gravity Settling," to be presented at the Air Pollution Control
Association's 71st Annual Meeting, Houston, TX, June 1978.
12. Borgwardt, R.H. U.S. Environmental Protection Agency, Sludge Oxidation in
Limestone FGD Scrubbers, EPA-600/7-77-061 (NTIS No. PB 268525/AS), June
1977.
13. Head, H.N., et al. Bechtel Corporation, "Results of Lime and Limestone
Testing with Forced Oxidation at the EPA Alkali Scrubbing Test Facility," in
Proceedings: Symposium on Flue Gas Desulfurization, Hollywood, FL,
November 1977, Volume I, EPA-600/7-78-058a, March 1978.
14. Rossoff, J., et al. The Aerospace Corporation, Disposal of By-Products from
Nonregenerable Flue Gas Desulfurization Systems: Second Progress Report,
EPA-600/7-77-052 (NTIS No. PB 271728/AS), May 1977.
15. Rossoff, J., et al. The Aerospace Corporation, "Landfill and Ponding Concepts
for FGD Sludge Disposal," to be presented at the Air Pollution Control
Association's 71st Annual Meeting, Houston, TX, June 1978.
16. Barrier, J.W., et al. Tennessee Valley Authority, Economics of Disposal of
Lime/Limestone Scrubbing Wastes: Untreated and Chemically Treated Wastes,
EPA-600/7-78-023a, February 1978.
17. Lunt, R.R., et al. Arthur D. Little, Inc., An Evaluation of the Disposal of
Flue Gas Desulfurization Wastes in Mines and the Ocean: Initial Assessment,
EPA-600/7-77-051 (NTIS No. PB 269270/AS), May 1977.
18. Holland, W.F., et al. Radian Corporation, Environmental Effects of Trace
Elements from Ponded Ash and Scrubber Sludge, Electric Power Research
Institute, Report No. EPRI 202, September 1975.
289
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CONTROL OF NITROGEN OXIDES FROM COMBUSTION
George Blair Martin
Joshua S. Bowen, Jr., D.Eng.
Industrial Environmental Research Laboratory (RTP)
U.S. Environmental Protection Agency
ADVERSE EFFECT
ON HUMANS
EMISSION SOURCES
Nitrogen oxides (NOX), principally nitric oxide (NO) and nitrogen dioxide
(NC>2), are atmospheric pollutants having the greatest potential for adverse effects on
human health and welfare. Human-activity originated emissions result in NOX
concentrations in urban atmospheres that are 10 to 100 times higher than those
from natural sources in nonurban areas. Fuel combustion in equipment contributes
about 99 percent of technology-associated NOX emissions. For most equipment,
about 95 percent of the NOX is emitted as NO and 5 percent as N02- In the
atmosphere, NOX enters into complex photochemical reactions with hydrocarbons
and sulfur oxides and results in the formation of undesirable secondary species, with
a shift of residual NO to NO2- The adverse effects of N02 and other pollutants on
humans, animals, vegetation, and exposed materials were among the factors which
led to passage of the Clean Air Act of 1970. With respect to NOX, this Act
empowered the EPA (1) to establish primary and secondary National Ambient Air
Quality Standards (NAAQS) for NO2, (2) to require a 90-percent reduction in NOX
emissions from light duty motor vehicles, (3) to establish New Source Performance
Standards (NSPS) for stationary sources, (4) to set up mechanisms to ensure
compliance and enforcement, and (5) to provide research, development, and
demonstrations of new and improved, commercially viable methods for the
prevention and control of pollution from the combustion of fuels. The Clean Air
Act Amendments of 1977 require EPA (1) to revise the NAAQS for NO2 to
consider short term effects (not more than 3 hours), (2) to implement a revised
level of automotive NOX control, (3) to require NSPS based on use of the best
technological continuous emission controls, and (4) to promulgate regulations for
prevention of significant deterioration of air quality. The Amendments also require
that any conversion of sources to coal firing be environmentally acceptable.
This section of the paper provides information on combustion generated NOX
which is necessary for a complete understanding of the EPA NOX control program.
In the United States in 1974, NOX emissions from human activity were
estimated to be about 23 metric tons per year. Of this amount, 46.1 percent was
estimated to come from mobile sources, 50.4 percent from stationary combustion
sources, and the remainder from miscellaneous sources. The stationary source NOX
can be further subdivided by the type of source and fuel burned to give a better
picture of the complexity of the problem. Table 1 represents the major divisions,
but each source can be further subdivided by equipment design.
Existing regulations for NOX fall into three categories: (1) ambient air quality
standards, (2) stationary new source performance standards, and (3) mobile source
standards.
291
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TABLE 1
Major sources of NOX
Source
Percent of Stationary
Source NOV
Utility Boilers - Coal
Utility Boilers — Oil and Gas
Package Boilers — Coal
Package Boilers — Oil and Gas
Warm Air Furnaces — Oil and Gas
Engines
Miscellaneous Sources
31.0
17.5
5.9
14.5
2.8
20.0
8.3
AMBIENT AIR QUALITY
STANDARDS
STATIONARY NSPS
To provide a basis for ambient air quality standards, available information was
compiled and analyzed by an advisory committee. The areas covered included not
only atmospheric chemistry, but also effects on materials, plants, and humans. A
major conclusion was that the ambient concentration of N02 should be used as the
basis of the standards. This was based on two main points. First, NO is rapidly
converted to N02 in the atmosphere and, second, toxicology studies of NO and
N02 indicate that N02 is the more hazardous form at concentrations found in the
atmosphere.
As required by the Clean Air Act of 1970, National Ambient Air Quality
Standards (NAAQS) for N02 were set in 1971. The primary standard is based on a
level required to protect the public health and the secondary, to protect the public
welfare from any known or anticipated adverse effect associated with the presence
of air pollutants in the ambient air. Both standards were set at 100 /jg/m^ for N02-
The Clean Air Act of 1970 required the EPA Administrator to set standards
for new sources. The only source category for which Federal New Source
Performance Standards (NSPS) are in effect is steam generators with a thermal input
greater than 73 MW (250 X 106 Btu/hr). The initial NSPS for this class of
equipment burning gas, oil, and coal (except lignite) became effective in 1971. The
lignite standard, which was promulgated in 1978, is based on firing method;
however, cyclone-fired boilers are only allowed for high sodium fuels. The NSPS are
summarized in table 2.
The basis of these regulations is combustion modification to reduce NOX
formation, and compliance is achieved with staged combustion and/or altered burner
designs.
TABLE 2
New source performance standards for steam generators
NSPS (NOX as N02)
Fuel
ng NOX/J
Ib NOX/106 Btu
Coal (except lignite)
Lignite
Pulverized Fired
Cyclone Fired
Oil
Gas
300
260
340
129
86
0.7
0.6
0.8
0.3
0.2
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MOBILE SOURCE STANDARDS
PENDING REGULATIONS
POLLUTANT FORMATION
THERMAL NO.,
FUEL
Although the IMOX control strategy in the Clean Air Act of 1970 was
predicated primarily on high level control standards for the automobile, the 1977
Amendments have eased the restrictions. The original standard of 0.24 mg/m (0.4
g/mile) for 1978 has been retained only as a research goal. This relaxation of the
automotive standard places increased emphasis on control of stationary source NOX
emissions. From the current standard of 1.9 mg/m (3.2 g/mile), the standard is
reduced to 1.2 mg/m (2.0 g/mile) through the 1980 model year, and to 0.6 mg/m
(1.0 g/mile) for 1981 and later.
There are pending regulations based on the Clean Air Act Amendments and on
establishment or revision of NSPS for stationary sources. Each major area is
discussed briefly.
The Clean Air Act Amendments require that the EPA Administrator
promulgate a short term N02 ambient air quality standard unless he finds that there
is no significant evidence that such a standard is needed to protect public health.
The Act also provides that the period of such a standard should be from 1 to 3
hours. A review of acute short term NO2 effects and the prevalence of critical levels
of NO2 in the atmosphere is underway and will be used as the basis of a decision
on the revision of the existing standard.
There are two areas under consideration for new or revised NSPS for steam
generators. First, the available data are being reviewed to identify demonstrated
technology for industrial boilers (less than 73 MW thermal, but greater than a
not-yet-established lower limit). The draft review document proposed a standard of
260 ng/J (0.6 1b/106 Btu) for bituminous coal and 220 ng/J (0.5 1b/106 Btu) for
lower grades of coal. Second, the data on NOX control for steam generators greater
than 73 MW thermal (utility and large industrial boilers) are being reviewed as the
basis for a revision of the current NSPS.
NSPS for both gas turbine and reciprocating engines are also being prepared.
The gas turbine standard has been proposed at 75 ppm (at 15 percent 02) for
nitrogen-free fuels, with a stepped approach for fuel nitrogen up to a maximum of
125 ppm (at 15 percent 02> for fuels with over 0.5 percent nitrogen.
The primary emphasis in EPA's NOX control technology development program
is on combustion modification to prevent pollutant formation. To optimize the
control technology for any given fuel, it is necessary to understand the mechanisms
by which NOX is formed and destroyed during combustion. Two distinct sources of
NOX, identified by the terms thermal NOX and fuel NOX, are discussed below. In
addition, it is necessary to ensure that control technology does not adversely affect
other pollutants or system efficiency. A brief discussion of these factors is also given
below.
The fixation of a small fraction of the molecular nitrogen in the combustion
air results in the formation of thermal NOX. Since the activation energies of several
of the formation reactions are high, the rate of formation of thermal NOX is
strongly temperature dependent. Thermal NOX is formed during the combustion of
all fuels in the regions of peak temperature that occur in all diffusion flames.
The oxidation of nitrogen compounds chemically bound in the fuel molecule
produces fuel NOX. Since significant amounts of nitrogen (0.1 to 2 percent by
weight) are found in all heavy fuels (residual oil and coal), fuel NOX is a major
contributor to the total NOX from these fuels. Based on small scale experiments, 50
to 90 percent of the total NOX from residual oil and coal is fuel related, even
though it is well established that only a fraction of the fuel nitrogen is converted to
NOX, with the balance forming molecular nitrogen. The main factor affecting the
conversion to NOX is oxygen availability. The reactions appear to be relatively
insensitive to temperature.
In general, a well designed boiler that is properly maintained and operated
produces low levels of carbonaceous pollutants (CO, HC, carbon particulate). Other
pollutant emissions (SOX and inorganic particulate) from these sources are less a
function of operation than of fuel composition and, in some cases, firing mode. On
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the other hand, stationary engines can emit significant amounts of CO and
hydrocarbon. Since the combustion control techniques for NOX require changes in
the way fuel is burned, they also present the opportunity for optimizing the total
combustion process to achieve low levels of other pollutants.
COMPLEX PROBLEM
VOLATILE EVOLUTION
Of all the fossil fuels currently used in the United States, coal is not only the
most abundant, but also presents the most complex problem of combustion and
emission control. In addition, there is no typical coal: properties of a given coal can
vary within the same seam. In spite of the wide ranges of composition that affect
both the way the fuel burns and the pollutant emissions, a general picture of the
important pollutant formation mechanisms can be presented by discussing
phenomena that occur for a single pulverized coal particle. For combustion in
practical systems, pulverized coal is mixed with a fraction of the combustion air
(called primary air) and introduced into the furnace through the fuel injector of the
burner. The amount of primary air is determined by both the fuel properties and
burner design; however, it is normally 10 to 30 percent of the theoretical air
required for complete combustion. The actual stoichiometry under which any fuel
particle reacts will depend on the fuel and air mixing history. The sequence of
events occurring for a single coal particle is shown in figure 1, which indicates two
combustion modes (volatile evolution and char burnout) as discussed below.
Although every coal particle undergoes similar types of processes, the environment
under which pollutant formation reactions occur is governed by the aggregate coal
particle cloud reaction history.
As the coal particle is heated by radiation and convection, the volatile portion
of the coal substance begins to evolve. The initial products contain carbon and
hydrogen and probably represent side chains and cross linkages between the ring
structures in the coal molecule. These initial volatiles react with the surrounding air
and partially deplete the available oxygen. As the temperature increases and the ring
structures begin to fragment, nitrogen containing intermediates (designated XN) are
evolved and begin to react with oxygen to form NOX. Subsequent reactions of XN
with NOX and other species produce molecular N2. The amount of nitrogen evolved
in the volatile fraction depends on the ultimate particle temperature; the fate of the
XN compounds depends on the local stoichiometry around the particle. For fuel
lean conditions, a substantial fraction will be converted to NO. For fuel rich
PORESjCRACKS
OR FISSUMES
INCLUSIONS OF
MINERAL MATTER
N2
NO
N2
DEVOLATILIZATION XN, XS
HETEROGENEOUS
NO REDUCTION
COAL PARTICLE
10 • 100 Aim
MINERAL MATTER
VAPORIZATION
CHAR BURNOUT NITROGEN
AGGLOMERATION OF
MOLTEN ASH
PARTICLE BREAK UP
NO
HOMOGENEOUS NUCLEATION
AND COLLISION COALESCENCE
° O O o
o ° 0° o
o o o
SUBMICRON ASH
HETEROGENEOUS
CONDENSATION
FIGURE 1— Pollutant formation during pulverized coal combustion
294
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CHAR BURNOUT
environments, the production of molecular nitrogen increases until an optimum
stoichiometry is reached; then, for even richer stoichiometries, the residual nitrogen
species (XN) are retained unreacted and burn in leaner secondary combustion zones.
It also appears that some of the NOX formed can be reduced to I\l2 by
heterogeneous reaction with coal particles or char. During this devolatilization process,
inorganic and organic sulfur species are released as sulfur intermediates (designated
XS). In general, the XS species are quantitatively converted to sulfur oxides (SC>2 or
803) at some point during the combustion process; however, these species may
undergo different reactions or may influence other reactions in this devolatilization
zone. Two examples may be cited. First a significant amount of the sulfur in some
western coals can be retained in the ash, probably as a sulfate; however, this
retention may be enhanced if the sulfur could be captured during devolatilization.
Second, sulfur species can influence the conversion of nitrogen species (XN) to NO
and other products; therefore, the history of sulfur intermediates relative to nitrogen
intermediates (XN) is important in the devolatilization zone. Finally, a portion of
the mineral matter from the coal is vaporized in the devolatilization zone and
subsequently condenses and/or coalesces to form submicron particulate. The
temperature and stoichiometry during devolatilization probably influences the
potential for fine particulate formation.
Following devolatilization, the residual coal matter (called char) is burned out.
The composition of the char depends strongly on the conditions in the
devolatilization zone; however, its major components are generally carbon and
mineral matter with variable amounts of nitrogen and sulfur species. By the nature
of coal combustion, char combustion occurs under predominantly fuel lean
conditions. By design, carbon burnout is nearly complete, thereby maximizing energy
efficiency and minimizing the carbonaceous particulate. The residual nitrogen species
in the char form NO and N2 during burnout in a mode of combustion which
appears to promote N2 formation. The sulfur species are either oxidized to SO2 or
retained with the mineral matter. The residual mineral matter forms particulate
(flyash) in the 0.1 to 50 /urn size range. Simultaneous with char burnout, residual
gaseous species (CO, H2, HC) must also be burned out. This mechanistic
understanding of pollutant formation processes forms the basis for optimization of
combustion techniques for emission control which are based on tailoring the air and
fuel mixing history to minimize all objectionable species.
NOX CONTROL TECHNIQUES
DILUENT ADDITION
Several control techniques can be applied to stationary combustion.
Combustion modification technology is the most cost effective and energy efficient
for conventional combustion sources. For any technique the degree of control
depends not only on the unit design but also on the fuel. Although NOX reductions
in excess of 80 percent relative to uncontrolled levels have been achieved by
combustion modification, even greater control may be required. This may be
obtained either by advanced combustion or by supplemental techniques such as
ammonia injection and flue gas treatment. The various techniques are described
briefly below.
The most effective control of thermal NOX is a reduction of the peak
temperatures in the flame zone. One approach is the addition of an inert diluent to
the fuel or air stream, thereby lowering the theoretical flame temperature at which
combustion takes place. The two most common approaches are flue gas recirculation
(i.e., the addition of relatively cool combustion gases recycled from the flue and
mixed with the combustion air) and water injection (i.e., addition of water or steam
to either the air or fuel stream). Of the two, water injection is the more effective
on a mass basis due to the latent heat of vaporization effect; however, it imposes a
stack heat loss that can be avoided with flue gas recirculation. These techniques are
most effective for thermal NOX and appear to have little effect on fuel NOX. For
example, 70 to 90 percent maximum reductions have been observed for natural gas
and distillate oil in field and laboratory studies; for heavy oil the range is 20 to 50
percent and for coal, 10 to 30 percent. Flue gas recirculation alone or in
conjunction with other techniques is used to achieve emission standards for gas and
oil fired utility boilers. Its potential drawbacks are increased mechanical complexity
and capital costs. Water injection is the state-of-the-art NOX control technique for
gas turbine engines.
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STAGED COMBUSTION
Staged combustion is based on creation of a rich primary combustion zone in
the furnace to reduce oxygen availability and peak temperature, followed by
secondary air injection to achieve carbon burnout. The reduced oxygen availability
reduces the conversion of fuel nitrogen to NO and the reduced peak temperature
and subsequent heat removal prior to secondary air addition reduces thermal NOX.
One method of implementing this control is illustrated in figure 2. The air supplied
to the burners is less than the amount necessary to completely combust the fuel,
which produces a fuel-rich primary zone. Although the effectiveness of staged
combustion increases significantly as the primary stoichiometry is decreased toward
75 percent of theoretical air, actual coal furnace primary zone stoichiometry is
limited to 95 to 100 percent theoretical air by operational considerations (e.g.,
SECONDARY
AIR
LEAN
SECONDARY
BURN OUT
ZONE
RICH
PRIMARY
ZONE
FIGURE 2-Staged combustion
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RECIRCULATED PRODUCTS
PRIMARY REACTION
ZONE
SECONDARY
REACTION
ZONE
CO, CHAR
BURNOUT
FIGURE 3-Burner design
BURNER DESIGN
slagging, corrosion). The secondary air is added above the top row of burners and
an equal or greater secondary zone residence time is provided for carbon burnout.
Although up to 90 percent reduction of NOX has been observed in coal fired
laboratory systems, the maximum practical reduction achieved on field operating
boilers under actual or experimental conditions is 30 to 50 percent. Staged
combustion is used in a number of configurations to achieve the NSPS for coal fired
steam generators and is also employed to meet standards for oil and gas fired units.
Although diffusion flame burners of many designs have been used in fuel
combustion for years, only recently has the modification of design approaches to
achieve emission control received strong emphasis. The essential elements of any
diffusion flame burner are a fuel supply and an air supply, generally represented in
figure 3. Design variables used to achieve stable combustion and good fuel
conversion efficiency include fuel distribution (controlled by injector design) and the
rate of air mixing (controlled by throat velocity, use of swirl, and/or design of the
flame holder). These same variables can control fuel and air mixing histories for
emission control; however, the flame characteristics required may be significantly
different than the conventional practice. As shown in figure 3, the fuel and air mix
initially in a primary reaction zone which contains a wide range of stoichiometries,
from very rich to very lean. This characteristic of diffusion flames appears to result
in the partial conversion of fuel nitrogen to NOX. The balance of the combustion
air is mixed with the primary zone products farther downstream and combustion is
completed. In addition, relatively cool combustion products recirculate within the
combustion chamber and are entrained by the flame. This entrainment can provide a
diluent effect which reduces peak temperature and, therefore, reduces thermal NOX.
Several pulverized coal burners designed to reduce NOX have been tested by boiler
manufacturers: reductions of 30 to 50 percent relative to uncontrolled levels have
been achieved. Entrained combustion gas recirculation burners have achieved NOX
reductions in excess of 50 percent for clean fuels (natural gas and distillate oil). In
addition, several studies of advanced burner designs for heavy oil and coal have
shown the potential for 65 to 90 percent reduction relative to uncontrolled
emissions. A modified burner design is currently used by one manufacturer to
achieve the NSPS for coal fired utility boilers.
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ADVANCED TECHNIQUES
Alternate combustion approaches do not employ classical diffusion flames and,
therefore, may allow very low levels of NOX. For example, catalytic combustion,
which is still being studied on the laboratory scale, has shown the potential for NOX
emissions below 10 ppm for clean fuels. Further development is required to assess
the full potential of this emerging technology in practical systems.
The ammonia injection technique involves the injection of ammonia (NH3)
into the boiler firebox above the combustion zone and the subsequent reduction of
Itie NOX to N2 by homogeneous reaction. The process requires careful NHs to NO
ratio control and injection at the proper temperature. Reductions of 90 percent have
been achieved in the laboratory? and in excess of 60 percent, in field operating
boilers. Due to reagent requirements, it is anticipated that this technique will be
used to supplement combustion control techniques where very low NOX levels are
required.
Many processes for NOX flue gases treatment have shown the potential for
high removal efficiency. These processes, generally categorized as wet and dry, are
discussed below:
DRY FGT PROCESSES
Selective catalytic reduction processes using ammonia as the reductant are the
most developed and most promising flue gas treatment processes. Although there are
many variations, anhydrous ammonia is usually injected into the flue gas after the
boiler economizer, and the resultant mixture is passed over a catalyst. The ammonia
selectively reduces the NOX in the presence of the catalyst to molecular N2 which
then passes out of the NOX removal system and into the boiler air heater. Selective
catalytic reduction processes can remove 90 percent of the NOX from the flue gas
of a combustion source. In Japan, selective catalytic reduction processes have been
successfully installed on commerical-scale gas- and oil-fired sources and are planned
for coal-fired sources. A few dry processes can simultaneously remove 90 percent of
the NOX and SC>2 in combustion flue gas. One of the more promising processes uses
copper oxide to absorb the SO2- The resulting copper sulfate acts as a catalyst in
the reduction of NOX to I\l2 with ammonia. A multiple reactor system is required
to allow for continuous treatment of the flue gas and regeneration of the reactor
saturated with copper sulfate. In the regeneration cycle, hydrogen is used to reduce
the copper sulfate, and a concentrated SO2 stream is produced which can be used
to generate a salable byproduct.
WET FGT PROCESSES
The wet processes are less developed than the dry and have more inherent
problems. The process chemistry is complex, and undesirable byproducts are often
generated. However, wet processes have the potential for simultaneous removal of
both NOX and SC>2 in a more economical and energy efficient manner than the
sequential installation of S02 and NOX flue gas treatment processes. Therefore, wet
NOX/S02 processes are receiving considerable developmental attention. The processes
can be subdivided into two general types: oxidation/absorption/reduction and
absorption/reduction. The oxidation/absorption/reduction processes basically evolved
from flue gas desulfurization systems. A gas phase oxidant, such as ozone or
chlorine dioxide, is injected before the scrubbers to convert NO to the more soluble
N02. The NO2 is then absorbed into an aqueous solution with S02- The absorbed
SO2 forms a sulfite ion which reduces a portion of the absorbed nitrogen oxides to
molecular nitrogen. The remaining NOX are removed from the waste water as nitrate
salts. The absorption/reduction processes were seemingly developed to avoid the use
of a gas phase oxidant. A chelating compound (such as ferrous-EDTA), with an
affinity for the relatively insoluble NO, is added to the scrubbing solution. The NO
is absorbed into a complex with the ferrous ion, and the SO2 is absorbed as the
sulfite ion. The NO complex is reduced to molecular nitrogen by reaction with the
sulfite ion. A regeneration step recovers the chelating compound and oxidizes the
sulfite ion into sulfate which is removed as gypsum. The wet processes can remove
90 percent of the NOX and SO2 from combustion flue gas.
The uncertainties of key variables make the quantitative prediction of future
trends very difficult; however, several factors appear to indicate the need for more
stringent NOX control capabilities in several areas. Some of these are discussed
briefly.
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INCREASED COAL USE
ALTERNATE FUELS
NOx CONTROL
PROGRAM STATUS
MAJOR PROGRAM
AREAS
The National Energy Plan calls for a significant increase in coal utilization by
industrial and utility sources. The actual increase depends on (1) coal production
capability, (2) energy consumption growth rate, (3) nuclear energy expansion rate,
(4) economics, and (5) environmental regulations. A first step is that virtually all
new utility boilers are coal fired. The result on NOX emissions from this source can
be generally illustrated by the fact that the current NSPS for coal-fired utility
boilers are 2.3 and 3.5 times those for oil- and gas-fired boilers, respectively. With
the current NSPS for coal-fired utility boilers, one recent projection indicates that
the increase in total NOX emissions from 1972 to 2000 would be 30 and 80
percent for high and low nuclear scenarios, respectively. Progressively higher levels of
emission controls through 1988 are required to significantly reduce the rate of
increase. Therefore, major emphasis on emission controls for coal-fired industrial and
utility boilers appears to be imperative.
Significant effort is underway in the United States to develop and
commercialize processes for producing alternative gaseous, liquid, or solid fuels from
coal or shale. Although most of these processes significantly reduce two of the
objectionable components (sulfur and mineral matter) associated with coal, they do
not eliminate chemically bound nitrogen. Typically, liquid fuels derived from coal
and shale have nitrogen contents from 0.5 to over 2.0 percent by weight. Although
this nitrogen can be at least partially removed by hydrotreating, it is potentially an
expensive and energy intensive process. Similarly, low and medium Btu fuel gas
produced from coal has the potential for containing up to 4000 ppm NH3 and
cleanup, particularly at high temperature, remains difficult. Evidence indicates that
combustion modification should be equally or more effective for alternative fuels
than for coal and heavy petroleum oil. Further development of the technology on
the specific fuels is required.
Very low levels of NOX may be required under several circumstances. First,
the short-term NO2 standard being considered may require stringent control in
certain areas. The degree of control and the specific sources requiring control for
any given location have not been established. It is also not obvious if large point
sources or area sources will be the prime target of control. Second, regulations
requiring the prevention of significant deterioration may require very low levels of
NOX in certain areas if development is to take place. Finally, certain local situations
may require increased NOX control capability. All of these factors provide impetus
for establishing the optimum control achievable by (1) conventional combustion, (2)
advanced combustion, and (3) postcombustion treatment.
The EPA's Industrial Environmental Research Laboratory at Research Triangle
Park, N.C., is vigorously pursuing a program to develop and demonstrate NOX
control technology for a broad range of combustion sources burning a variety of
fuels. Based on both experience and projections, major program emphasis is on coal
combustion in industrial and utility boilers. Other source/fuel combinations are also
covered, based on similar considerations. The program's technical approach is based
on a balanced and coordinated mix of technology application, technology
development, and fundamental research. In general, technology being readied for
evaluation in field applications has been developed under EPA sponsorship.
Optimization of the technology at the development stage has resulted from an
empirical experimental approach and a complementary fundamental understanding of
critical phenomena in the NOX formation and destruction process. The major
program areas are briefly described below, then a more detailed discussion of
selected projects is presented.
Major projects of EPA's NOX control technology program are grouped into
four general classifications for convenience of discussion: (1) technology development
and field evaluation for specific sources, (2) optimum technology development, (3)
fundamental combustion research, and (4) environmental assessment and application
testing. Due to the diversity of source/fuel combinations in the first classification, an
individual discussion is provided below for each source category. Activities in the
other three areas are discussed under more general headings.
Many, if not all, new utility and industrial boilers with a thermal input greater
than 35 MW will be fired with pulverized coal. Since the equipment of this type has
299
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EVALUATION OF CORROSION
RATES
STOKER COAL-FIRED
BOILERS
GAS TURBINES
RECIPROCATING ENGINES
the same general configuration (i.e., multiburner, wall- or tangentially-fired,
field-erected watertube boijer), combustion modification approaches for NOX control
are also quite similar. Two major projects relate directly to this type of equipment:
one for existing combustion technology; the other for application of an advanced
low NOX burner.
Current new boilers designed to meet the NSPS incorporate staged combustion
and/or improved burners in conjunction with the normal firing design. There has
been mixed evidence for the existence or extent of accelerated waterwall corrosion
with the fuel-rich conditons that may be produced in the lower part of the firebox.
Therefore, a project has been initiated to fully evaluate these effects on four boilers
of different firing configurations operating at or below the NSPS of 300 ng NOX/J
(0.7 Ib NOX/106 Btu). The evaluation of corrosion rates will include the use of
both removable corrosion panels and ultrasonic tube thickness measurements before
and after a 6 month operating period. This project, which should begin soon, will
provide both a quantitative definition of any problem and identification of needed
control approaches.
An advanced design low NOX pulverized coal burner for application to both
industrial and utility boilers has been developed under the EPA program. The size of
individual burners in this class of boiler ranges from about 10 to 80 thermal MW
(30 to 240 X 10^ Btu/hr). The advanced low NOX burner has been tested on an
experimental scale of 15 to 20 MW and has consistently given NOX levels below 86
ng/J (0.2 Ib NOX/106 Btu). The burner is being tested at up to 37 thermal MW
with various fuels, and smaller burners are being tested in multiple burner arrays. A
field evaluation of the technology is planned on two industrial boilers in the range
of 30 to 150 thermal MW and on two utility boilers in the range of 100 to 300
electrical MW. A more extensive discussion of this project is in the next section of
the paper.
The stoker boiler firing system can be used for commercial and industrial
boilers in the range of 4 to 120 thermal MW, but, above approximately 40 MW,
pulverized coal may be cost competitive. A project is in progress to evaluate
emission control technology on a model stoker firing a variety of natural and
processed coals. Results of these experiments will be used to guide the development
studies using a captive spreader stoker boiler. This study will determine the degree
of NOX control using a variety of techniques, including overfire air ports for staged
combustion. A new program was recently initiated to apply this technology to two
field operating boilers.
The stationary engine category is composed of two general classes of engines,
gas turbines and reciprocating engines.
Current gas turbine engines use a diffusion flame combustion mode which is
similar in principle to that found in boilers, but different in practice because of very
high combustion intensities and high pressure operation. Gas turbines currently use
clean fuels (natural gas and light oils); however, there appears to be a trend toward
the use of heavier liquid fuels with significant concentrations of fuel nitrogen. For
clean fuels, the NOX emissions, which are quite high, can be controlled using water
injection, although efficiency and water supply problems may be encountered. This
technique is not expected to be effective on the fuel NOX for the heavier liquid
fuels. For these reasons, a combustor development project was initiated for dry
control of both thermal and fuel NOX from stationary gas turbine engines. The
concept screening experiments are complete and a combustor design has been
identified capable of exceeding the program goals (i.e., 50 ppmv at 15 percent 02
for clean fuels and 100 ppmv at 15 percent 02 for fuels with up to 0.5 percent
fuel nitrogen). The successful concept is being scaled up to the size of a single
combustor segment in a practical laboratory evaluation. Following successful
completion of these tests, the combustor will be incorporated in a practical engine
for evaluation on a test stand.
A similar development program is also in progress on large bore diesel and
spark ignition reciprocating stationary engines. Potential engine design modification
concepts are being screened by a panel of experts with the help of an analytical
300
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RESIDENTIAL FURNACES
FLUE GAS TREATMENT
ADVANCED PROCESSES
LOW EMISSION BURNER
model. A limited number will be selected for experimental evaluation, and the
successful concept(s) will be applied to an engine under laboratory conditions.
The degree of control achievable with current oil and gas fired residential
furnaces is limited by the relative lack of flexibility of operating conditions and by
cost constraints. This class of equipment emits pollutants near ground level in
populated areas during a limited period of the year (i.e., the heating season). In
addition, it consumes a significant amount of energy, almost exclusively as clean
fuels (e.g., gas and light oil). An integrated residential oil furnace has been
developed in the laboratory and has been tested in six residences over one complete
heating season. Its performance met or exceeded the emission goals (i.e., NOX < 0.6
g/kg, CO < 1.0 g/kg, UHC < 0.1 g/kg, and smoke number < 1 on the Bacharach
scale), and measured cycle average efficiencies ranged from 73 to 80 percent (based
on gross heating value). The furnace concept has been tested with natural gas, and
shows promise for that fuel although more development is required.
Two bench scale evaluations of promising NOX and NOX/SOX flue gas
treatment processes are underway. Each evaluation will encompass four phases: (1)
design, (2) procurement and erection, (3) startup, debugging, and optimization, and
(4) long-term operation and assessment. The projects should be completed in
mid-1980. The results will, in large measure, enable an assessment of the viability of
NOX and NOX/SOX flue gas treatment technology for application to United States
coal-fired boilers. The NOX project will evaluate the Hitachi Zosen selective catalytic
reduction process using ammonia. Application of the process, expected to remove 90
percent of the NOX from the flue gas, will be the first test of the technology on a
coal-fired boiler in the United States. The NOX/SOX project will evaluate the Shell
Copper Oxide process, expected to remove 90 percent of both the NOX and SOX
from the flue gas. The project will be the first test of this technology on a
coal-fired source anywhere in the world.
Advanced processes provide engineering exploratory research for identification
of advanced concepts capable of significant emission reductions from the levels
achievable with state-of-the-art control technology. For example, both the low NOX
coal burner and the integrated residential furnace concepts originated from these
studies. The general approach of these projects is to use versatile experimental
systems to develop technology for low emission combustion of a specific fuel. Such
projects now underway are discussed briefly below.
The low NOX coal burner work is being continued for evaluation of the
effects both of coal properties covering the full range of United States coal reserves,
and of single and multiple burner configurations on the ultimate emission levels. A
complementary study of burner design and burner furnace interactions has been
initiated for tangentially fired coal boilers using a small versatile furnace (3 to 6
thermal MW).
A low emission burner design program for heavy liquid fuel combustion is also
in progress. Work has shown that over 65 percent reduction in emissions from
residual fuel oils containing up to 0.8 percent N can be obtained with a staged
burner design; however, beyond this limit a significant increase in carbon particulate
occurs. Recent work has shown that both the fuel atomizer design and the
properties of the liquid fuel have a strong effect on emission control. Promising
burner designs for both firetube and watertube package boilers have been identified
and are being optimized. In addition, the exploration of fuel effects has been
expanded to include synthetic liquid fuels derived from coal and shale, for which
the residual oil technology is expected to be directly applicable.
Several low and medium Btu gases simulating the products from three types of
air oxygen blown gasifiers have been evaluated at 3 thermal MW in an experimental
furnace. Burner configurations representing both boiler and kiln practice were used
during the program. For ambient and elevated temperature fuel gases, the thermal
NOX emissions could be correlated with adiabatic flame temperature. When NH3 was
added to the gases for simulation of one potential component of actual coal derived
fuel gases, a significant conversion to NOX was observed. With the addition of
similar amounts of H2S, simulating residual sulfur compounds in actual gases, the
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IMH3 INJECTED
INTO BOILER
FUNDAMENTAL COMBUSTION
RESEARCH
HEAVY FUEL STUDY
GAS PHASE
CHEMICAL KINETICS
conversion of NH3 to NO increased substantially. It should be noted that this
observation relates to phenomena previously noted in fundamental combustion
experiments. It was concluded that burner modification or staged combustion would
be required to control NOX from NH3 containing gases. In a second related project,
calculations showed the potential for substantial reduction of NOX from high
temperature, NH3-containing low Btu gases by proper application of staged
combustion. These calculations are being evaluated in an experimental study which
will define the optimum combustor configuration based on fuel gas properties. The
most promising concepts will be constructed and evaluated in bench scale
experiments.
The homogeneous thermal reduction of NOX by injection of NH3 into the
boiler at a specified temperature region of the postcombustion zone has been shown
experimentally for oil and gas fired systems. A project is underway to evaluate the
applicability of this technique to coal fired systems. A laboratory study is in
progress and a feasibility study will be conducted for the use of the technique as a
supplement to combustion modification on a coal fired boiler.
Catalytic combustion is an advanced combustion concept with the potential for
very low levels of pollutant emissions from clean fuels (e.g., NOX, CO, and UHC all
less than 10 ppm). For application to stationary sources, further development of
systems aspects are required. A detailed discussion of the results to date is given in
the next section of this paper.
Fundamental combustion research studies provide the basic understanding of
the phenomena responsible for pollutant formation and destruction in the
combustion process. These studies emphasize the chemistry and aerodynamic aspects
of combustion processes and are used to guide the development and optimization of
new technology. Special attention is being directed at fuel nitrogen reactions and at
the formation of primary and secondary pollutants since these species may be
strongly affected by changes in the combustion process. Projects in this area
examine the classes of phenomena which can be associated with specific elements of
the conventional combustion process: (1) fuel pyrolysis, (2) gas phase kinetics, and
(3) fuel/air mixing. All experimental aspects are complemented by analytical
modeling.
The fuel pyrolysis studies have shown that a significant amount of the fuel
nitrogen in both heavy oil and coal is evolved as an organic nitrogen intermediate at
temperatures below 873K and that this intermediate can be further pyrolyzed almost
quantitatively to HCN at 1373K. Drop-tube furnace experiments at higher
temperatures (e.g., 2100K) have shown that the nitrogen can essentially be
completely evolved from the coal substance with sufficient residence time.
Measurements have also shown that the nitrogen and sulfur compounds from a range
of coals show different evolution patterns as a function of temperature. This
information is currently being examined to determine if it can be directly related to
NOX emissions as a function of combustion condition in an experimental furnace. A
similar drop-tube experiment has begun to derive similar high temperature pyrolysis
information for heavy liquid fuels.
Although the general effects of diffusion flame burner conditions on emissions
from pulverized coal and oil flames have been known for some time, an
understanding of the behavior of these fuels under well defined flow conditions has
not been achieved due to experimental and analytical difficulties. In the past year
several projects have been initiated to study these heavy fuels in simplified reactors
(e.g., plug flow, well-stirred, and simple diffusion flames). Results of these studies
will be utilized to define the effects of air/fuel mixing history on pollutant
formation.
Finally, even for these heavy fuels, an understanding of the gas phase chemical
kinetics is necessary to understand the mechanics of formation and control of fuel
NOX. The use of chemical kinetics codes coupled with experimental data has shown
that the fuel characteristics can have a dramatic effect on the fractional conversion
of NH3 to NO for a given reactor type. It has also shown that a careful control of
stoichiometry (rate of air addition) and temperature can have a significant effect on
302
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fuel NOX from a given fuel/reactor combination. This type of information can
provide a direct input to development studies for practical combustors.
ENVIRONMENTAL ASSESSMENT
AND FIELD APPLICATION
Environmental assessment and application testing provide for a near-term
evaluation of the effects of state-of-the-art combustion techniques on the total
emissions from stationary sources. The environmental assessment project has been
evaluating all aspects of the problem, while field application projects have been
evaluating the effects of combustion techniques on specific classes of equipment.
APPLICATION TESTING
A preliminary environmental assessment has been completed and various
aspects of NOX control have been documented, including (1) source types, (2) fuel
usage, (3) emissions baseline, (4) state-of-the-art control techniques, (5) developing
control technologies, (6) potential side effects, and (7) total impact evaluation
methods. The projected fuel use and emission trends have been estimated for five
energy growth rate and supply scenarios. The impact on NOX from each source
sector has been estimated, based on various assumptions on level of control.
Although about 30 sources contribute significant amounts of NOX, coal fired boilers
are identified as the user sector most likely to increase dramatically by the year
2000 in almost all scenarios. In addition to the system analyses in this project, a
program is underway to evaluate the impact of NOX controls on other emissions
from a range of sources. These studies will compare emissions between baseline and
low NOX conditions for field operating boilers using EPA, IERL-RTP Level 1 and 2
procedures for sample collection and analysis. Several residential oil furnaces and a
coal fired utility boiler have been sampled; however, results are not yet available.
In general, to ensure the environmental acceptability of the technology, the
environmental assessment measurement methodology is being incorporated in some
measure on developmental studies and in full on field evaluation projects.
Application testing allows the evaluation of the extent of control achievable by
optimization of low NOX conditions within the constraints imposed by existing
combustion equipment under field operating conditions. Projects are underway or
were recently completed in several areas. A United States emission inventory based
on available data has recently been updated. Two gas and oil fired industrial size
boilers equipped with emission control equipment including flue gas recirculation and
staged combustion have been evaluated. Emission reductions up to 79 percent were
achieved for natural gas and distillate oil, while reductions up to 55 percent were
achieved for residual fuel oils containing approximately 0.3 percent nitrogen.
Carbonaceous emissions and unit efficiency were unaffected or improved for the
optimum conditions. A long term corrosion test on a coal fired utility boiler is
complete; however, data analysis is still in progress.
DETAILED DISCUSSION
LOW IMOX COAL BURNER
Several areas in EPA's NOX control program will result in the ability to
achieve control levels significantly higher than is currently possible. To provide a
more complete understanding of the technical approach, two of the more promising
areas have been selected for a more detailed discussion. The low NOX coal burner
technology has the potential for direct application to new and existing pulverized
coal fired industrial and utility steam generators. Catalytic combustion is a
longer-term technology that may require a significant redesign of combustion
equipment to achieve its full potential; however, it offers the potential for near zero
emission levels (i.e., NOX, CO, and HC less than 10 ppm) for clean fuels commonly
used in area sources.
Since the control of both thermal and fuel NOX from pulverized coal
combustion is strongly dependent on the temperature and stoichiometry in the
primary zone, the most direct approach is to redesign the burner to achieve the
required fuel/air distribution. In 1971 the EPA initiated a small scale study to
identify the important burner design parameters for NOX control. This study
identified a distributed air burner concept that had the potential for very low NOX
emissions with both high carbon utilization efficiency and acceptable flame
characteristics. This pilot scale work was carried out at thermal heat inputs of 1.5
to 3.0 MW, which is a factor of 10 to 40 smaller than practical pulverized coal
303
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SCALING CRITERIA
burners currently in use. Due to difficulties in scaling burner thermal performance
by even a factor of 2, current design practice is to make incremental capacity
changes, or simply install more burners of the same size. Therefore, to obtain
industry acceptance of the low NOX burner technology, it was necessary to identify
scaling criteria and to evaluate the burner performance at as close to practical size
as possible. A project was initiated to develop scaling criteria for low emission
burners. As an essential part of the program, a unique combustion facility capable
of firing coal and other fuels at a thermal input up to 40 MW was designed and
constructed. The important features of this facility are shown in figure 4. The basis
8.4m
«— 3.6m*-
MINIMUM
VOLUME
7.2m
MAXIMUM
VOLUME
12.7m
• FUELS: -
PULVERIZED COAL
HEAVY OIL
FIRING CAPACITY:
15 - 40 THERMAL MW (50-120 X 106Btu/hr)
HEAT RELEASE RATE:
1.6 to 2.4 kW/m3
VARIABLE GEOMETRY
SHEET STEEL WALLS:
WATER SPRAY COOLED
PULVERIZER-RAYMOND CE (MOD 473A):
6000 kg/hr
AIR PREHEAT TEMPERATURE:
700K
INDEPENDENT CONTROL OF ALL AIR STREAMS
GROUND LEVEL
FIGURE 4—Large watertube boiler simulator
FIGURE 5-Conceptual sketch of low NOX burner system
304
-------
SWIRL VANES
DAL &_^
^IMARY
R
/•
r^
SECONDARY
AIR
XI
.,._.
IX
TE
1
rc
RTIARY
AIR
RETRACTABLE
OIL
NOZZLE
CERAMIC
COMBUSTOR
WALL
FIGURE 6-Sketch showing major features of 15-thermal-MW distributed mixing burner
EXPERIMENTAL
BURNER DESIGN
of the low NOX coal burner is a distribution of the combustion air to control the
reaction history of the coal. This is shown conceptually in figure 5. The coal is
introduced with primary air and the initial devolatilization reaction takes place at a
very rich stoichiometric ratio (SRi) which results in evolution of fuel nitrogen
intermediates (XN) under conditions where oxidation to fuel NOX is low. Secondary
air is introduced in a way which provides a gradual leaning out of the reaction zone
to a stoichiometry (SR2) which is still fuel-rich. This gradual mixing allows
formation of NOX and a subsequent reduction by XN to form N2. Both the
temperature and stoichiometry history of this rich reaction zone determine the level
of NOX that can be achieved. Finally, tertiary air is mixed with the reaction
products to give a lean burnout zone (SR3>. In this zone any residual XN species
are converted predominantly to NO, any nitrogen remaining in the char is converted
predominantly to N2, and fuel species (char, CO, HC, H2) are oxidized to give
complete combustion. Complete reaction of the carbon in the char is especially
important from the standpoint of both efficiency and emission performance. The
design of the experimental burner used to achieve these conditions is shown in
figure 6. The design incorporates a retractable oil gun for use on startup and a
divided secondary air channel to provide flexibility on turndown. The three burner
sizes used in the program are nominal thermal inputs of 4, 20, and 40 MW. A
typical plot of experimental data is shown in figure 7 where NOX emissions are
shown as a function of the burner primary zone equivalence ratio (numbers greater
than 1.0 are fuel-rich). The 16 MW thermal burner produces emission levejs below
150 ppm (86 ng NOX/J) for a primary zone equivalence ratio greater than 1.2,
which corresponds to less than 80 percent of the theoretical air being supplied
through the primary and secondary air channels of the burner. (Note that a
geometrically scaled burner at 3 MW thermal produces somewhat higher NOX levels.
This may be attributable to a residence time in the fuel-rich reaction zone that
increases as burner scale increases or to changes in rate of secondary air mixing rates
for the larger jet diameters. Whatever the reason, it is encouraging to observe that
increasing scale toward practical size appears to make the technology more
effective.)
305
-------
400
c
0)
u
1_
CD
Q.
E
a
a.
300
200
100
30% EXCESS AIR
O 15 THERMAL MW
D 2.7 THERMAL MW
(VARIABLE RESIDENCE
TIME)
0.8 1.0 1.2 1.4 1.6
PRIMARY ZONE EQUIVALENCE RATIO
FIGURE 7-Scale effect with distributed mixing low NOX coal burner
1.8
RESULTS OF LOW
BURNER DESIGN
DEMONSTRATED TECHNOLOGY
To evaluate the applicability of the technology to other fuels, a limited series
of experiments was run with a high nitrogen residual fuel oil; a typical example is
shown in figure 8. Although the nitrogen in the oil is high (0.77 percent) compared
with the average (about 0.25 percent) for residual oil used in the United States, it
provides both a worst case for conventional oils and a preview of what may be
achievable with high nitrogen coal- and shale-derived oils. The results shown are for
unstaged operation (i.e., a small amount of purge air through the tertiary injectors)
at three thermal inputs, 2.4 MW for the small burner and both 12 and 15 MW for
the intermediate burner. The intermediate scale burner operated down to 2 percent
oxygen in the flue without producing carbon particulate (smoke) and gave NOX
levels of about 175 ppm. This can be compared with approximately 1200 ppm of
fuel NOX that would occur if the 0.77 percent nitrogen were quantitatively
converted and 350 to 600 ppm that would occur at levels of conversion observed in
conventional burners.
Development of the low NOX coal burner technology is continuing to expand
the applicability of the design and scaling criteria for the full range of United States
coals. This includes small scale screening of a large number of coals followed by
testing of selected coals at the three burner scales. Additional burner concepts with
the potential for improved emission performance are being evaluated and the
influence of multiple burner configurations on flame interaction is being assessed. To
provide a comparison with commercial practice and an estimate of the effect of
multiple burner interactions in practical systems, several full scale production coal
burners will be evaluated in the experimental facility. A technical review panel,
composed of representatives of boiler manufacturers, utilities, and research
organizations, provides a continuing evaluation of the program direction as related to
practical systems. A technology transfer panel, composed of representatives of
government agencies and trade association members, periodically provides a broader
perspective of potential users.
To provide for demonstrated technology, two projects have been initiated for
field evaluation of the low NOX burners. One project covers two industrial boilers in
306
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the range of 30 to 150 thermal MW, while the other involves two utility boilers in
the range of 100 to 300 electric MW. The projects provide for (1) construction of
one prototype burner of each size and validation of performance in the experimental
facility, (2) baseline emission characterization of the host boilers, (3) installation of
the required number of burners in each boiler and optimization of performance, (4)
long term performance evaluation, including required environmental assessment and
periodic operational analyses, and (5) preparation of a guideline manual for
generalization of the technology. These projects should begin in late 1978 and be
completed in late 1982. The goals of these projects are to show that (1) NOX
emissions below 86 ng/J are possible in practical boilers, (2) low NOX emissions can
be achieved without increased carbonaceous emissions, (3) thermal efficiency of the
boiler is equal to or better than that of the baseline boiler, and (4) the burner
design provides an air shield around fuel-rich zones and, as a result, waterwall
corrosion is eliminated.
CATALYTIC COMBUSTION
One advanced concept that appears capable of achieving very low pollutant
levels is catalytic combustion, where a catalyst is used in place of a diffusion flame
burner to achieve the major energy release in a combustion system. The initial
applicability is to clean gaseous and vaporizable liquid fuels, as a premixed fuel and
air stream must be presented to the catalyst. Oxidation of the fuel through both
400 —
CM
O
c
O)
o
300
E
Q.
a
200
100
NO.6 OIL
0.77% N
UNSTAGED
S = 0.38
FIRING RATE:
O 12 THERMAL MW
D 15 THERMAL MW
• 2.4 THERMAL MW
(VARIABLE RESIDENCE
TIME)
3
percent
FIGURE 8-Low NOX burner firing residual oil
307
-------
350
300 -
250 -
200
CN
O
•M
c
-------
heterogeneous surface reactions and homogeneous gas phase reactions occurs within
the channels of the catalyst bed at essentially adiabatic temperature. Complete
combustion can be achieved at very short residence time and with very high
volumetric heat release rates. The two apparent limits are (1) the temperature at
which catalyst degradation becomes significant, and (2) the well known kinetic
threshold temperature above which the rate of thermal NOX formation becomes
significant. Therefore the application of the technology to stationary combustion
sources requires new system designs to achieve long life and high thermal efficiency.
STATIONARY GAS TURBINES
The most straightforward application of catalytic combustion appears to be
stationary gas turbine engines. Several features of this class of equipment are ideally
suited to catalytic combustion: (1) clean fuels are used extensively, (2) the normal
mode of operation is at high excess air where the adiabatic flame temperature
(1373K) is well within the capability of catalysts, (3) high volumetric energy release
rates and compact combustors are desirable, (4) a flat combustor exit temperature
profile, as produced by a catalyst bed, is highly desirable, and (5) control of
emissions to very low levels by conventional techniques is difficult. Figure 9 shows
typical data from a versatile test facility for several catalysts burning premixed
methane/air at high excess air. The maximum bed temperature is controlled by the
amount of air supplied to the fuel. At current gas turbine combustor outlet
temperatures (1373K), the NOx emissions are well below 10 ppm (about 6 ng/J) for
both catalysts. This can be compared with NOX emissions from conventional engines
with water injection of about 150 ppm (about 86 ng/J). As the catalyst temperature
increases, NOX emissions increase gradually to 10 to 20 ppm at 1723K, after which
the increase is more rapid. In the catalysts, where surface reactions are believed to
dominate, emissions are about 80 ppm at 1973K; for the catalyst where
homogeneous gas phase reactions dominate the fuel burnout, emissions are over 300
ppm at that temperature. These results illustrate two points: (1) very low NOX
emissions can be achieved even at the highest temperatures that may be achieved at
the turbine inlet of advanced combined cycle systems, and (2) the catalyst plays a
significant role in the level of emissions observed. For all tests CO and hydrocarbon
emissions were also low. The most significant problem that was encountered was
catalyst substrate degradation at the high temperature operation. Further
development of catalysts and auxiliary systems is required for the incorporation of
the catalyst into practical engines.
STATIONARY BOILERS
The application of catalytic combustion is more difficult for stationary boilers
that must operate at low excess air to achieve high thermal efficiency. For example,
the adiabatic temperature for natural gas at stoichiometric air to fuel ratio is over
2250K, or well in excess of the desirable operating range of the catalyst. Therefore,
alternative concepts must be sought. One such alternative is shown in figure 10. A
stoichiometric mixture of fuel and air is introduced to the radiative section and
combustion takes place on the catalyst cylinders (denoted by ®). The surface
temperature of the cylinders is controlled at about 1373K by radiation to
surrounding watertubes (indicated by -0-). Approximately 50 percent of the fuel
heating value would be released in this section with about 50 percent of the energy
released being removed by the watertube. The radiative section is followed by a
transition section in which more heat may be removed as required. The high
temperature mixture of air, fuel, and combustion products is then introduced to a
graded cell catalyst where complete combustion occurs at an adiabatic temperature
below 1723K. The convective section then reduces the gas temperature to a flue
value around 450K which, coupled with a stoichiometric air to fuel mixture, results
in the minimum practical heat loss achievable without a condensing heat exchanger.
The coolant flow through the radiative, transition, and convective section watertubes
must be arranged to achieve the desired steam temperature and pressure. Although
the total system has not been tested, a prototype of the radiative section has been
evaluated experimentally: it performed as expected on heat release and heat removal
parameters. Low NOX values were measured and there is no reason to suspect an
increase in the adiabatic combustor based on graded cell tests of catalysts at similar
temperatures. It is also anticipated that low fuel NOX emissions can be achieved by
use of staged combustion either in the radiative concept or with two adiabatic
sections. Preliminary tests have confirmed this for nitrogen doped gaseous fuels.
309
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SUMMARY Tne status of EPA's IMOX control technology development program can be
summarized as follows:
• Based on fuel trends, NOX emissions may increase significantly with current
technology.
• More effective stationary source control technology can provide a means of
mitigating this emission trend.
• The combustion modification techniques under development offer the
potential for achieving significant NOX reductions without adverse effects on
other pollutants.
• These high levels of control can also be achieved at relatively low cost and
without degradation of thermal efficiency.
• If extremely low levels of NOX are required, advanced combustion
technology and supplemental techniques such as ammonia injection and flue
gas treatment are also under development.
The authors wish to thank Dr. M. P. Heap and Dr. J. Kesselring for the
information used in the detailed discussion of the low NOX coal burner and
catalytic combustion, respectively.
310
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References
Ando, J., K. Nagata, and B.A. Laseke. "IMOX Abatement for Stationary Sources in
Japan." PEDCo Environmental, Inc., EPA-600/7-77-103b (NTIS No. PB 276-948/AS),
September 1977.
Bowen, J.S. and R.E. Hall. "Proceedings of the Second Stationary Source
Combustion Symposium, Volume l-Small Industrial, Commercial and Residential
Systems, Volume Il-Utility and Large Industrial Boilers, Volume Ill-Stationary
Engine, Industrial Process Combustion Systems, and Advanced Processes, Volume
IV-Fundamental Combustion Research, Volume V-Addendum." Industrial Environ-
mental Research Laboratory-RTP, EPA-600/7-77-073a, -073b, -073c, -073d, -073e
(NTIS Nos. PB 270-973/AS, 271-756/AS, 271-757/AS, 274-029/AS, 274-897/AS),
July 1977.
Burrington, R.L., J.D. Cavers, and A.P. Selker. "Overfire Air Technology for
Tangentially Fired Utility Boilers Burning Western U.S. Coal." Combustion
Engineering, Inc., EPA-600/7-77-117 (NTIS No. PB 277-012/AS), October 1977.
Carter, W.A., H.J. Buening, and S.C. Hunter. "Emission Reduction on Two Industrial
Boilers with Major Combustion Modifications." KVB Engineering, Inc.,
EPA-600/7-78-099a (NTIS No. later), June 1978.
Cato, G.A., K.L. Maloney, and J.G. Setter. "Reference Guide for Industrial Boiler
Manufacturers to Control Pollution with Combustion Modification." KVB
Engineering, Inc., EPA-600/8-77-003b (NTIS No. PB 276-715/AS), November 1977.
Crawford, A.R., E.H. Manny, and C.W. Bartok. "Control of Utility Boiler and Gas
Turbine Pollutant Emissions by Combustion Modification-Phase I." Exxon Research
and Engineering Company, EPA-600/7-78-036a (NTIS No. PB 281-078/AS), March
1978.
Dykema, O.W. "Effects of Combustion Modifications for NOX Control of Utility
Boiler Efficiency and Combustion Stability." Aerospace Corporation,
EPA-600/2-77-190 (NTIS No. PB 273-057/AS), September 1977.
Engleman, V.E. "Proceedings of the Engineering Foundation Conference on Clean
Combustion of Coal." Science Applications, Inc., EPA-600/7-78-073 (NTIS No.
later), April 1978.
Faucett, H.L, J.D. Maxwell, and T.A. Burnett. "Technical Assessment of NOX
Removal Processes for Utility Application." Tennessee Valley Authority,
EPA-600/7-77-127 (NTIS No. PB 276-637/AS), November 1977.
Janssen, J.E., J.J. Glatzel, E.R. Wabasha, and U. Bonne. "Study of a Thermal
Aerosol Oil Burner." Honeywell Corporation, EPA-600/7-77-108 (NTIS No. PB
277-438/AS), September 1977.
311
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Kemp, V.E., and O.W. Dykema. "Inventory of Combustion-Related Emissions from
Stationary Sources (2nd Update)." Aerospace Corporation, EPA-600/7-78-100 (NTIS
No. PB 282-4287AS), June 1978.
Mason, H.B., A.B. Shimizu, J.E. Ferrell, G.G. Poe, L.R. Waterland, and P.M. Evans.
"Preliminary Environmental Assessment of Combustion Modification Techniques:
Volume I. Summary." Acurex Corporation, EPA-600/7-77-119a (NTIS No. PB
276-680/AS), October 1977.
Mason, H.B., A.B. Shimizu, J.E. Ferrell, G.G. Poe, L.R. Waterland, and R.M. Evans.
"Preliminary Environmental Assessment of Combustion Modification Techniques:
Volume II. Technical Results." Acurex Corporation, EPA-600/7-77-119b (NTIS No.
PB 276-681/AS), October 1977.
Salvesen, K.G., K.J. Wolfe, E. Chu, and M.A. Herther. "Emission Characterization of
Stationary NOX Sources: Volume I. Results." Acurex Corporation,
EPA-600/7-78-120a (NTIS No. later), June 1978.
Salvesen, K.G., M.A. Herther, K.J. Wolfe, and E. Chu. "Emission Characterization of
Stationary NOX Sources: Volume II. Data Supplement." Acurex Corporation,
EPA-600/7-78-120b (NTIS No. later), June 1978.
Schalit, L.M. and K.J. Wolfe. "Sam/IA: A Rapid Screening Method for Assessment of
Fossil Energy Process Effluents." Acurex Corporation, EPA-600/7-78-015 (NTIS No.
PB 277-088/AS), February 1978.
Shoffstall, D.R. "Burner Design Criteria for NOX Control from Low-Btu Gas
Combustion, Volume I. Ambient Fuel Temperature." Institute of Gas Technology,
EPA-600/7-77-094a (NTIS No. PB 272-614/AS), August 1977.
Shoffstall, D.R. and R.T. Waibel. "Burner Design Criteria for NOX Control from
Low-Btu Gas Combustion, Volume II. Elevated Fuel Temperature." Institute of Gas
Technology, EPA-600/7-77-094b (NTIS No. PB 280-199/AS), December 1977.
Tyson, T.J., M.P. Heap, C.J. Kau, B.A. Folsom, and N.O. Brown. "Low NOX
Combustion Concepts for Advanced Power Generation Systems Firing Low-Btu Gas."
Energy and Environmental Research Corporation, EPA-600/2-77-235 (NTIS No.
later), November 1977.
Waterland, L.R., H.B. Mason, R.M. Evans, K.G. Salvesen, and K.J. Wolfe.
"Environmental Assessment of Stationary Source NOX Control Technologies: First
Annual Report." Acurex Corporation, EPA-600/7-78-046 (NTiS No. PB
279-083/AS), March 1978.
Authors unnamed, "EPA's Stationary Source Combustion Control Technology
Program FY 1976." Acurex Corporation, EPA-600/7-77-077 (NTIS No. PB
270-086/AS), July 1977.
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FLUIDIZED-BED COMBUSTION
Steven I. Freed man, Ph.D.
Energy Technology Branch
Department of Energy
CONCENTRATED
SOLAR ENERGY
The goals of all of us are clean, efficient, practical, economic generation of
heat and power from whatever original energy sources are available. For that reason
many people have become interested in solar energy. Figure 1 shows pre-packaged,
FIGURE '\-Coal
313
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CLEAN COMBUSTION
TEMPERATURE ADVANTAGE
COAL BURNED
IN FLUIDIZED BED
aged, concentrated solar energy, which we know as coal. There are large quantities
of it in the U.S. We find numerous references to the abundance of coal in our
nation-400 years' supply at current usage rates. The problem is how to use it in an
environmentally acceptable and economic manner.
Fluidized-bed combustion is one of the advanced concepts for the clean
combustion of coal (figure 2). It is a way of burning coal, as well as agricultural
and industrial wastes, in a clean, practical and economic manner. Fluidized-bed
incinerators are now used to burn paint wastes and bark and log fuels from paper
mills and lumbering operations. The concern of the Department of Energy is to
develop this technology to burn coal while controlling SC>2 emissions. This fuel
flexibility is an important practical feature of the fluidized-bed system. Fluidized-bed
combustors are more compact than conventional coal combustors. This equipment
size advantage is a consequence of the higher heat transfer coefficients that are
inherent in the process.
Every once in a while nature is cooperative. The temperature for fluidized-bed
combustion is from 1450 to 1650 degrees Fahrenheit, which is advantageous for
several reasons. It is sufficiently high for efficient combustion, below the
temperature at which ash slags and forms deposits on tubes, above the temperature
required to generate superheated high-pressure steam for power generation, and
below the temperature at which NOX will form from nitrogen in the combustion air.
The combustion temperature is above that at which limestone and dolomite calcine
to lime and below the temperature of dissociation of calcium sulfate, so that
calcium sulfate is produced as the by-product of burning sulfur-bearing fuels. The
lower NOX formation is a consequence of the lower combustion temperatures. The
unburned carbon in the bed offers a modest possibility for dissociating the
fuel-bound nitrogen so that NOX emissions can be reduced to the range produced by
oil and natural gas-fired equipment and, in the longer-range future, perhaps even
lower. The solid waste is a mixture of unreacted lime, ash, gypsum, and calcium
sulfate. Some useful alternative methods of disposal have been demonstrated and will
be discussed later.
Figure 3 shows coal being burned in a fluidized bed. The bed is contained in
a pyrex tube so that the process can be seen. Air is injected at the bottom through
a porous-plate air distributor that also supports the bed. The illustration shows a
mixture of non-combustible particles—hot sand in this case—and a few coal particles
which have been fluidized by the air passing through. The air rises in bubbles, which
can be seen in the middle, with the particles falling back into the bed.
Figure 4 depicts schematically a fluidized-bed combustor with an integral heat
exchanger. The bed is a dense phase of lime and coal particles and air, in which
ATMOSPHERIC FLUIDIZED BED COMBUSTION
• COMPLIANCE WITH S02 EMISSION REGULATIONS
WITHOUT SCRUBBERS
• LOW NOX EMISSIONS DUE TO LOW COMBUSTION
TEMPERATURES
• FLEXIBILITY OF COAL SUPPLY, i.e. ABILITY TO BURN
VARIOUS FUELS INCLUDING LOW RANK COALS
• POTENTIAL FOR SMALLER BOILER VOLUMES DUE TO
HIGH HEAT TRANSFER COEFFICIENTS OF IN-BED SURFACES
• DRY SOLID WASTE MATERIAL
FIGURE 2-Advantages of AFBC
314
-------
FIGURE 3-Fluidized bed combustion of coal in a pyrex tube
BED:
98% INERT
SOLIDS,
2% COAL;
TEMPERATURE
1,550°F
oo ooooo o oo
o ° ° o • o o o o
o o oo o oo
0,9)000 O 00 O O O OA \°
Q0°gdQ oo • OOP o Qo°7 .
o°o °^°
oo o o m
a a
O SORBENT/ASH
• COAL
o
0 °o o
en a en
COOLANT
2/3 OF ENERGY
REMOVED
BY IN-BED HEAT
EXCHANGERS
FLUIDIZING/COMBUSTION AIR
FIGURE 4-Fluidized bed combustion-schematic
315
-------
COMBUSTOR WITH HEAT
EXCHANGER
heat transfer coefficients are quite high and the gas-solid contact area is enormous,
so that the SO2 in the combustion products can react with the lime. There is a
small amount of coal in the bed, about 2 percent. This devolatilizes first and then
burns. The limestone calcines to lime from the heat of combustion and then picks
up to S02 to become sulfate. The heat transfer tubes are immersed in the bed in
order to control the temperature to the range of optimum SO2 capture and
combustion efficiency.
Figure 5 shows the process development unit that was in existence in our
Alexandria, Virginia, laboratory from 1965 until 1977. It has been replaced with a
FIGURE 5-FBC process development unit (I) Alexandria, VA-schematic
316
-------
FBC IN A BOILER MODE
CONTINUOUS OPERATION
new unit with a higher freeboard so that additional R&D can be undertaken on
NOx control, SO2 absorption, and suppression of unburned hydrocarbons in the
above-bed zone.
Figure 6 is a sketch of the fluidized bed in a boiler mode. This is our unit at
Rivesville, West Virginia. You can see the fluidized-bed region with the in-bed tube
bundle, over-bed heat exchange tubes, and the fuel injection ports.
Figure 7 shows the power plant at Rivesville, West Virginia, where the
30-megawatt experimental boiler is installed.
Figure 8 shows the Rivesville 30 MWe boiler assembled but without insulation
and all the coal injection ports connected.
Figure 9 shows the four cells of the Rivesville boiler. The three cells to the
right are each 10 feet wide, 12 feet long, and 20 feet high. The in-bed heat
exchanger has both steam-raising and superheating tubes. The above-bed heat
exchanger includes both preheating (economizer) and steam-raising tubes. The cell on
the extreme left is the carbon burnup cell.
Recently, the Rivesville unit achieved continuous operation over an extended
period. During a forced outage this winter, the coal feed system was improved, and
in May the unit operated continuously for 50 hours. During that period, the steam
FUEL
INJECTION
PIPES
1550 F
PLENUM
AIR
DISTRIBUTION
GRID
FIGURE 6-FBC boiler
317
-------
FIGURE 7-Power plant at Rivesville, WV
FIGURE 8-Multi-ceIl fluidized bed boiler at Rivesville, WV
318
-------
SOLID WASTE DISPOSAL
generated was used by the host utility to generate power for the electric power grid.
The usual 24-hour startup was adequate to achieve controlled steady-state operation
that is prerequisite to connecting with the host system. Preliminary data from
Rivesville indicate that the S02 reduction is in the range of 85 to 89 percent with
the limestone feed that is presently being used there, and NOX emitted is 0.2 to 0.3
Ib. per million Btu. Presently, connections are being made in the flyash reinjection
system so that the improved combustion efficiency expected with this carbon
recycle feature can be demonstrated.
Solid waste from FBC units can be disposed of in the same manner as
conventional flyash and stabilized scrubber wastes, at a cost of about $2 to $4 per
ton. As alternatives to disposal, some useful applications for the waste product have
been demonstrated. For example, cement blocks made with this waste have strength
comparable to regular commercial block. The waste product can be used as a dry
benign substance for parking lots, road base, and other low-grade structural
applications.
Cell "D
FLUIDIZED BED
STEAM GENERATOR
DEMONSTRATION UNIT
Cell "C"
Cell "Bf
Cell "A'
Typical section thru coils
FIGURE 9-Kivesville MFB-schematic
319
-------
,x*ii ^ '**': s^ ^to-fC'^S^VS.rrfr /;>-4''
s^;Si^^*l
FIGURE 10—Peanuts grown using FBC solid waste
WASTE BY-PRODUCT
GREATER EFFICIENCY
Figure 10 shows another application of waste by-product. Peanuts were grown
using fluidized-bed waste as a substitute for land plaster, which is a mixture of lime
and gypsum. Most crops require sulfur. A certain amount of sulfur is removed from
the soil and forms part of the crop. Ordinary grass has been grown in greenhouses
with sulfur-free atmospheres, as contrasted to the ambient atmosphere, which
contains a small amount of SC>2, and in greenhouses with atmospheres containing
controlled amounts of SO2- With no sulfur provided, either via the air or the soil,
the growth of ordinary grasses is about half of its maximum capability. That seems
to be true of other crops also. FBC solid wastes can be a convenient source of
replacement sulfur. We intend to continue this program of evaluating the use of
fluidized-bed waste as a nutrient to soils and as a construction material.
Figure 11 shows the Georgetown University industrial boiler. The fluidized bed
is the shaded area in the center, with an ordinary convective pass above it and the
air distributor plate below it. The boiler will produce 100,000 pounds of steam an
hour at 675 psig pressure for cogeneration application.
My discussion so far has focused on atmospheric fluidized-bed combustion, in
which the combustion chamber operates at pressure within a few inches of water of
atmospheric pressure. Pressurized fluidized-bed combustion (PFBC) at pressures 6 to
16 times atmospheric pressure is being investigated as a means of burning coal for
gas turbines. The air for the PFBC comes from the compressor of the gas turbine
that is energized by combustion products from the PFBC. By recovering heat from
the gas turbine exhaust for a steam turbine unit, the overall combined cycle
efficiency of extracting energy from coal is increased above that achieved with
conversion cycles based on combustion at atmospheric pressure.
The efficiency of central station coal-fired power plants several years ago was
in the 39 to 40 percent range. When the need for cooling towers arose, the
efficiency was reduced to about 38 percent, and the pump circulation and reheat
power for scrubbers lowered this even further to about 34 percent. The atmospheric
pressure fluidized bed promises to save the fan and reheat power energy losses
associated with scrubbers, with an overall plant efficiency in the range of 36 to 37
percent. The combined cycle mode of operation with pressurized, fluidized beds has
a potential overall plant efficiency of up to 40 percent.
Beyond the advantage of higher efficiency, and to this particular audience
perhaps the prime advantage, is the fact that the data from the pressurized
combustion of coal show lower NOX, better limestone or dolomite utilization and a
potential for greater SC>2 absorption.
320
-------
VALUE OF CONCEPT
The fluidized-bed system is viewed as a combined environmental,
energy-efficient, and economically advantageous new system. The value of the entire
fluidized-bed combustion concept lies in the compliance with allowable S02
emissions, the opportunity perhaps to improve on that, compliance with allowable
NOx emissions, and the opportunity to achieve lower NOX than the current
standards. The NOX emissions from FBC are down in the range of those for
combustion of low nitrogen oil and natural gas. Multi-fuel flexibility is another
advantage of fluidized-bed combustion. Fluidized beds have been used to burn low
grade coal, high sulfur coal, wastes from coal cleaning plants, industrial wastes, and
forest residues.
The materials, technology, and shop labor needed to manufacture the
equipment for fluidized beds is the same as that for conventional boilers, but the
higher heat transfer coefficients in fluidized beds are more compact. Because the
fluidized-bed boiler requires less material, it is probably less expensive than a
conventional boiler. The optimization of design and fabrication techniques is
expected to convert material savings into a 10-percent saving in boiler costs.
LOW NOX LEVELS
Fluidized-bed combustion is a cleaner, more efficient, and potentially lower
cost method of coal combustion. With the continued use of coal through the year
2000, at the predicted rates, fluidized-bed combustors will permit lower NOX levels
by a substantial amount, perhaps 30 percent. The overall environmental impact of
burning coal can be further moderated by employing the benign solid wastes
produced by the fluidized-bed combustion process as a substitute for other extracted
resources.
STEAM OUTLET
GAS
OUTLET
FLUIDIZED BED STEAM GENERATOR
GEORGETOWN UNIVERSITY
100,000 LBS./HR. 675 PSIG. DESIGN PRESSURE
SATURATED STEAM
SPREADER
COAL FEEDERS
(TYP)
MUD
DRUM
DOWNCOMER
AIR INLET
FIGURE 11 -Georgetown fluidized bed stream generator
FLY ASH
REINJECTOR
LIMESTONE
FEED PIPE
DOWNCOMER
\
BED MAT'L
DRAIN (TYP)
SAIR DISTRIBUTION
GRID LEVEL
321
-------
CONTROL OF PARTICULATES FROM COMBUSTION
Dennis C. Drehmel, Ph.D.
James H. Abbott
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
EMISSION ESTIMATES
HIGHLY VARIABLE PROPERTIES
PHYSICAL STATE
Millions of tons of particulates are emitted into the atmosphere every year. In
the year 1976, the total nationwide emission estimates were 13.4 million metric tons
of which stationary fuel combustion sources contributed 4.6 million metric tons (1).
Most stationary fuel combustion emissions were from electric utilities and were
estimated to be 3.2 million metric tons. As of 1975, the total electric power
generation for fossil fuel plants of 25 MW or greater was 347,720 MW (2). Of this
total, 60% was generated with coal; 19%, oil; 21%, gas. Between now and 1990,
combustion of gas and oil is expected to remain relatively constant but the
combustion of coal could almost double (3). Hence, particulates from cumbustion
are not only a major source of total particulates now but also a continuing problem
for the future.
The properties of combustion particulates or fly ash are under intensive study
and are known to be highly variable. For example, the particle size distribution can
include a small or large fraction in the respirable range. Tests performed by EPA's
Industrial Environmental Research Laboratory at Research Triangle Park (IERL/RTP)
show that the mass median diameter can range from 9 to 50 /um(4,5,6) for fly ash
from coal-fired power plants (figure 1). Because of the large size distribution of fly
ash (geometric deviations of 3.3 5.0), even a mass median diameter as large as 50
Hm implies a significant emission for particle sizes less than 3 /jm. It has been
estimated that coal-fired power plants release 0.6 million tons/year in the 1-3 ,um
range, 0.2 in the 0.5-1.0 A/m range, and 0.1 in the 0.1-0.5 /Km range (7). Coal-fired
industrial boilers and oil-fired power plants and industrial boilers also have significant
emissions in the 1-3 /urn range of 0.1 and 0.2 million tons/year, respectively (7).
Other properties of interest for fly ash are the physical state and composition.
With respect to physical state, fractions of fly ash have been characterized according
to relative abundance of 12 morphological classes (8). The most abundant forms
were the nonopaque solid spheres and nonopaque cenospheres. Other important
types were the rounded, vesicular nonopaque and the amorphous nonopaque.
Variation in physical state with particle size has been noted with predominance of
the opaque solid spheres in the submicron range. Morphology can be related to
composition. Coal components give the opaque amorphous particles, iron with
silicates give opaque spheres, and silicates give nonopaque particles.
323
-------
LU
N
CO
CO
CD
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<
2
LU
O
DC
99.9
98
90
70
50
30
10
2
0,5
0.1
0.01
99.99
99.8
99
95
80
60
40
20
1
0.2
0.05
SAMPLING DEVICE:
o SOVIET MODEL I
a SOVIET MODEL II
O U.S. BRINK IMPACTOR
8>
I
I I I
I III
JL
I III
0.1 0.4 0.8 2.0 6.0 10.0 40.0 80.0
0.2 0.6 1.0 4.0 8.0 20,0 60.0 100.0
AERODYNAMIC PARTICLE DIAMETER,^.m
FIGURE 1—Typical inlet size data for coal-fired power plant paniculate
TRACE ELEMENTS
ESP'S
SCRUBBERS
Trace elements are to be found in fly ash and in some cases represent a
significant fraction of the total emission of that element (9). Annual emissions in
coal-fired power plant fly ash for arsenic are 493 tons; beryllium, 99 tons; lead, 706
tons; and mercury, 173 tons. Given the above trace elements, the toxic and
carcinogenic effects of fly ash are suspected. Currently, biological testing has shown
that both organic and inorganic mutagens are present in coal fly ash (8). Further
testing is needed to determine if these mutagens are also carcinogenic.
For conventional combustion sources, the control options available are
electrostatic precipitators (ESP's), fabric filters, scrubbers, cyclones, and combinations
of devices such as an ESP followed by a scrubber. With respect to ESP applicability,
IERL/RTP tested them on coal-fired utility boilers and concluded that a high level
of control was possible even for very small particles (table 1 and figure 2). It is
believed that the removal efficiency of an ESP would drop rapidly for particles
below about 2 /urn in size. This is the size at which the main particle charging
mechanism called field charging begins to become ineffective. Even in the submicron
range, these results indicated that significant collection, and thus particle charging,
occurs. The charging process, which comes into significance on these very small
particles, is termed diffusion charging. ESP's are widely used today on coal-fired
utility boilers. They cost more to install than scrubbers or fabric filters, but they
are less expensive to operate. The main drawback to current ESP's is their inability
to effectively and economically trap certain types of fine particles-such as fly ash
from low-sulfur coal. These are particles with high electrical resistivity, which makes
them difficult to collect electrostatically without incurring very high initial capital
costs.
Wet scrubbers have been used as particulate collection devices since the early
1920's. Although they are inexpensive to install compared with large baghouses or
ESP's, scrubbers are costly to operate. They require large amounts of water and
electricity and create a sludge.
324
-------
TABLE 1
Results of field tests on electrostatic precipitators
SCA
Type sq m/actual
Source
Coal-Fired
Boiler
Coal-Fired
Boiler
Coal-Fired
Boiler
Coal- Fired
Boiler
ESP
Cold Side
Cold Side
Cold Side
Hot Side
cu m/sec
54
54
65
85
Efficiencies, % Particle Diameter
Tempera-
ture, °C
150
160
160
375
Over-
all
99.6
99.8
98.3
99+
2
micron
98.9
99.9
99
99.6
1
micron
97
99.6
96
97
0.5
micron
95
99
80
95
0.1
micron
98
99
98
99.3
Comments
Moderate sulfur
coal
High sulfur coal;
no impactor data
Low sulfur coal
Tests completed;
data not reported
99.99
99.9
99
95
£
8 90
>
UJ
o
50
10
5
0.1
0.01
0.01
ALABAMA POWER COMPANY
CAT-OX PRECIPITATOR
.PILOT PLANT PRECIPITATOR
. HOT PRECIPITATOR
1 1 1
0.1 1.0
PARTICLE DIAMETER,/urn
10.0
FIGURE 2—Measured efficiency as a function of particle size for precipitators
SCRUBBERS TESTED
lERL/RTP's Particulate Technology Branch has tested scrubbers of
conventional design on a variety of particulate sources. In general, the efficiency of
a scrubber drops off rather rapidly as the particle size decreases (figure 3). The
efficiency is directly related to the energy consumed by the scrubber. Table 2 shows
these results in terms of the cut diameter and in terms of the diameter at which the
efficiency falls below 80%.
325
-------
>-
CJ
99.99
99.9
99
95
90
50
10
5
0.1
0.01
0.01
.VENTURI ROD
. T.C.A.
.WETTED FIBROUS /
VENTURI
I I I I I MM
I I I I I Illl
0.1 1.0
AERODYNAMIC PARTICLE.^m
10.0
FIGURE 3-Fractional efficiency versus aerodynamic diameter for scrubbers
TABLE 2
Fine particle control by scrubbers
Smallest Diameter
Collected at Stated
Name
Ducon
Wet Fiber
Chemico Venturi
UOP/TCA
Venturi Rod
Pressure Drop,
cm WC
8
19
25
30
273
Efficiency, ;iim
80%
1.6
1.1
0.9
0.7
0.5
50%
1.3
0.6
0.7
0.35
0.3
COLLECTION EFFICIENCY
The Particulate Technology Branch (PATB) has also tested collection efficiency
down to 0.08 p.m and found that scrubbers, have a minimum in their collection
curves analogous to ESP's. The efficiency of a TCA scrubber on a coal-fired power
plant decreased to 30% collection at 0.4 urn and then increased back to 97% to
0.08 jum (figure 4). As with the ESP minimum, two mechanisms are involved. For
coarse particles, collection is by impaction and for very fine particles, collection is
by diffusion. Since 0.4 jitm diameter particles have neither a high diffusivity nor a
large inertial mass for impaction, they are the most difficult to collect.
326
-------
FABRIC FILTERS
Fabric filters or baghouses have the highest efficiencies in collecting particulate
emissions and are the most effective in controlling fine particulates. The Particulate
Technology Branch has tested two installations on utility boilers and one on an
industrial boiler (10,11). The results of these tests show greater than 95% collection
at all sources in all size ranges tested from 0.1 to 4 ^m (figure 5). Following are
the results for each site:
• At the Sunbury pulverized coal-fired power plant with glass/Teflon bags and
an air-to-cloth ratio of 2, the overall mass removal efficiency was 99.9%.
The outlet loading was 0.0039 grams/m3 (0.0017 g/dscf). The efficiency
was 99% at 0.1 jum, near 98% at 0.5 Aim, and above 99% at 1.0 jum.
• At the Nucla stoker coal-fired power plant with graphited glass bags and an
air-to-cloth ratio of 3, the overall mass removal efficiency was 99.8%. The
outlet loading was 0.0071 g/m3 (0.0031 gr/dscf). The efficiency was 99% at
0.1 jum, 99% at 0.5 /urn, and greater than 99% for 1.0 urn.
• At the Kerr Industries stoker coal-fired industrial boiler with Nomex bags
and an air-to-cloth ratio of 3, the overall efficiency was 99.2%. The outlet
loading was 0.0046 g/m3 (0.002 gr/dscf). The efficiency was almost 99% at
0.3 jum, about 95% at 0.6 /urn, and back up to greater than 98% at 2.0 jum.
z
°
o
<
I-
oi
•z.
Ill
o-
LLI
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1.0
0.5
0.4
0.1
0.1
0.02
0.01
II I I I I |
ii i i i i I
0.04 0.07 0.1
0.2 0.3 0.4 0.5
1.0
I I
\\
T DIFFUSION BATTERY RUNS
•IMPACTOR RUNS
_L
i i i i
0.2 0.5 1.0
PARTICLE DIAMETERVm
2.0
5.0
FIGURE ^-Fractional efficiency of a TCA scrubber
CYCLONES
Among the least expensive particulate collectors are cyclones. These are widely
used to clean up industrial operations like grinding and polishing metals, crushing
stone and gravel, and woodworking. Though cyclones are very efficient for large
particles, they are only about 40% efficient for fine particles. The efficiency of
cyclones can be improved by increasing the velocity of the airflow—but only at the
cost of substantially more energy. As a result, cyclones work best on sources that
do not emit great numbers of fine particles such as combustion sources.
327
-------
o
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O
99.99
99.9
99
95
90
50
10
5
1
0.1
0.01
0.01
AVERAGES OF 2 TO 8 TESTS
SINGLE POINT DATA
INDUSTRIAL BOILER
J L
0.1 1.0
PARTICLE DIAMETER. Atm
10.0
FIGURE 5—Baghouse performance on utility boilers
CONTROL DEVICE
COMBINATIONS
Recently, combinations of control devices have become of interest. The use of
scrubbers for S02 control combined with other devices for particulate control offers
some potential advantages. If the particulate control device treats the flue gas before
the scrubber, the scrubber circuit will be relatively free of fly ash, allowing easier
treatment or reuse of scrubber products. If one of the control devices must be
taken out of service for maintenance, the remaining control device will continue to
collect the primary pollutant for which it was designed and may also provide some
collection for the other pollutant. If the combination of interest is an ESP followed
by an SC>2 scrubber, both the control devices provide particulate collection and the
ESP may be designed smaller than one not followed by the scrubber. This last
conclusion resulted from a PATB in-house study using pilot scale equipment and
computer models which produced the results shown in figures 6 and 7. Figure 6
shows the penetration curves for each control device by itself. As noted previously,
the efficiency of the scrubber decreases rapidly with decreasing particle size, and
efficiency of the ESP decreases more slowly to a minimum around 0.5 jum.
Comparing the 95% efficient ESP and the scrubber with a 25 cm. pressure drop
shows that the scrubber is more efficient above 0.8 jum and the ESP more efficient
below 0.8 /urn. In combination they add to each other's capability with the result
shown in figure 7. To achieve this result with a scrubber alone, the pressure drop
would have to be increased greatly to collect the very fine particles. Similarly, with
an ESP alone, the specific collector area (SCA) would have to be increased greatly
to collect large particles as efficiently as the ESP/scrubber combination. Working
together, the ESP and scrubber can provide collection capabilities equal to more
expensive single devices because of the different ways ESP's and scrubbers collect
different particle sizes.
328
-------
LJJ
z
LU
Q.
0.9
0.7
1.0
0.8
0.6
0.5
0.4
0.3
0.25
0.2
'0.15
0.09
0.07
0.10
0.08
7
0.06
0.05
0.04
0.03
0.025
0.02
0.015
0.01
ESP CURVE >
EFFICIENCY = 95%
SCRUBBER CURVE
PRESSURE DROP = 25 cm '
I I I I I I I
0.15 0.2 0.3 0.4
0.25
0.5
1.0
1.5 2 2.5 3 456789
10
AERODYNAMIC PARTICLE DIAMETER,
FIGURE 6-'Predicted penetration as a function of particle diameter
ADVANCED POWER CYCLES
PRESSURIZED FBC
For advanced power cycles, control options include granular beds, ceramic
filters, dry scrubbers, and high temperature/pressure ESP's. These devices must be
applied to the specialized requirements of coal gasification, magnetohydrodynamics
(MHD), or fluid bed combustion (FBC). In coal gasification, coal is converted to
synthetic gas by burning under carefully controlled conditions at high temperature
and pressure—temperatures as high as 1830 C at 1 atmosphere and pressures up to
100 atmospheres at 930°C. Much of the energy in the coal is retained by the
synthetic gas to be burned in gas turbines, boilers, furnaces, kilns, or heaters. As
supplies of natural gas become less abundant, it is proposed to use synthetic gas
produced by coal conversion in pipelines to industries and homes, eliminating the
need to replace gas-burning equipment now in use.
Another important coal conversion process is pressurized FBC. Here, coal is
burned under pressure in a bed of limestone or similar material resulting in 820°C
combustion gases to be cleaned. The sulfur in the coal is removed by the limestone
in the bed. The combustor generates both steam for electric power or industrial
uses, and hot pressurized gases, which can be used to drive gas turbines. Typical gas
parameters and particulate characteristics of gasifier and FBC streams are shown in
table 3.
Since these processes are at high pressure, the control device must be
contained in a pressure vessel and hence it is economically imperative to keep the
control device small. Since operating temperatures for the control device are above
820 C, ceramic materials must be used as collection media. Granular beds and dry
329
-------
CONTROL DEVICE
scrubbers use discrete ceramic particles as collection sites. In a granular bed, the
ceramic particles are fixed or moving with the particulate laden gas passing through
the bed. Collection is by impaction, interception, and diffusion. In a dry scrubber,
the ceramic particles fall through the particulate-laden gas which can be accelerated
as in a venturi scrubber in order to maximize impaction collection. The ceramic
filter can be either a ceramic membrane barrier or a ceramic baghouse. The high
temperature/pressure ESP is likely to be similar to conventional low temperature
wire-and-pipe designs.
0.9
0.7
o
<
H
LLJ
Q_
1.0
0.8
0.6
0.5
0.4
0.3
0.25
0.2
0.15
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.025
0.02
0.015 -
0.01
I I
I I I
0.15 0.2 0.3 0.4 0.5
0.25
1.0 1.5 2 2.5 3 4 5 6 7 8 9 10
AERODYNAMIC PARTICLE DIAMETER,^m
FIGURE 7-Predicted penetration as a function of particle diameter for ESP and scrubber
TABLE 3
Ranges of gas steam and particulate characteristics for advanced energy processes
Temperature, °C
Pressure, atm
Mass Loading, g/Nm
Mass Median Diameter, /urn
Gas Composition (Major
Components)
FBC
760-980
1-10
0.09-4.8
1.2-8
N2, CC>2, O2
H2O, SO2, NO, CO
Gasifier
150-1,100
1-70
18-230
<300
H2, CO, C02, N2
H20, CH4, H2S
330
-------
PARTICULATES
NATIONAL R&D PROGRAM
LOW SULFUR COAL
CONDITIONING AGENTS
Particulates are one of the six air pollutants thus far identified by the
Environmental Protection Agency (EPA) as having "potential for widespread adverse
effects on human health and welfare." Acting on the authority of Section 109 of
the Clean Air Act, December 1970, EPA has set a primary National Ambient Air
Quality Standard of 75 micrograms per cubic meter (annual average) for total
suspended particulates. Within the same act, Section III, EPA was also given the
authority to set standards of performance for new stationary sources. The Act as
revised by the 1977 Amendments states that the standard should reflect "the degree
of emission limitation achievable through the application of the best system of
continuous emission reduction which (taking into account the cost of achieving such
reduction and any nonair quality, health and environmental impact and energy
requirements) the Administrator determines has been adequately demonstrated for
that category of sources." For particulate emissions from utility boilers, the current
limit is 43 ng/J (0.1 Ib/million Btu)(12). A revision in this standard is currently
under consideration. Preliminary drafts suggest that the standard might be 13 ng/J
(0.03 Ib/million Btu). Another possible control standard which would apply to
particulate from combustion sources is Section 112 of the 1970 Clean Air Act
Amendments which deals with national emission standards for hazardous air
pollutants. This, standard would apply to an air pollutant which may cause an
"increase in mortality or an increase in serious irreversible, or incapacitating
reversible, illness."
As part of the development and enforcement of air pollution standards,
Section 103 of the 1970 Clean Air Act Amendments states that EPA will establish a
national research and development program which will, among other activities, do
the following:
• Conduct and promote the acceleration of research, experiments, and
demonstrations relating to prevention and control of air pollution.
• Conduct investigations and research and make surveys concerning specific
problems of air pollution.
• Develop effective and practical processes, methods, and prototype devices
for the prevention or control of air pollution.
It has been estimated that, in the next 15 years, coal consumption will
increase dramatically because of dwindling supplies of oil and natural gas. By 1990,
total coal consumption is expected to be close to 1.3 billion tons annually, which is
almost twice the current rate.
Much of the coal burned today is eastern coal mined in Pennsylvania, Illinois,
West Virginia, and Kentucky. However, since the early 1960's the use of western
coal has expanded dramatically, partly because of increased western energy needs
and stricter SC>2 emission control requirements. Some of the low sulfur western coal
is being shipped to eastern plants to avoid the need for flue gas desulfurization.
With the enactment of the Clean Air Amendments of 1977, SC>2 emissions from
new coal combustion sources must be reduced by a constant percentage whether
western or eastern coals are fired. This will make it more difficult to comply with
future federal new-source performance standards by firing low sulfur western coal
without flue gas treatment. Consequently, expanded use of low sulfur western coal
to meet SC>2 control regulations will be tempered. In spite of this mitigating factor,
it is expected that there will be a substantial increase in the use of western low
sulfur coal.
Unfortunately, cpmbustion of low sulfur coal produces fly ash with high
electrical resistivity which is difficult to collect. Current solutions to the low sulfur
coal particulate control problem include conditioning of the fly ash and changes in
operating temperature of the ESP. Experience with conditioning agents can be
summarized as mixed. They work sometimes and don't work other times. It is
impossible to predict in advance which additive and how much of it will allow a
given ESP to work. Probably the major unresolved problem with conditioning agents
is their environmental impact. Even under best case conditions, the use of
conditioning agents changes the chemical composition of the particulate, and in
331
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HOT-SIDE ESP'S
PROBLEMS AND LIMITATIONS
PARTICLE CHARGING
some cases the gaseous emissions of a power plant. At least in some cases, this
change in chemical composition may have adverse environmental impact.
If the operating temperature of the ESP is either lowered or raised, the
resistivity of the fly ash is lowered and performance of the ESP enhanced. The
typical application of this effect is to place the ESP before the air preheater instead
of after the preheater in the power plant flue system. The precipitator is then on
the hot side of the air preheater and operates at 400°C instead of 150°C. Although
hot-side ESP's used by eastern utilities are satisfactory, hot-side ESP's used to
control participate emissions from power plants in the west burning low sulfur
western coal perform worse than expected. The reason for the poor performance of
these hot-side ESP's in the west is at present unknown.
In addition to problems with particulate from combustion in conventional
systems, a new set of problems arise in advanced power cycles. Process constraints
dictate control of particulate emissions at high temperature and pressure where
materials problems are a major concern. The particulate matter under these
conditions may be sticky or tend to agglomerate and blind the collection surface of
the control device. Potential control devices are by and large only in an early state
of development and high temperature cyclones will not meet current, much less
revised, standards applied to conventional power systems.
Granular bed filters are being evaluated at the Exxon miniplant and at Air
Pollution Technology, Inc. Difficulty in cleaning the bed has resulted in efficiencies
falling from 92% to 46% during a 24-hour run at Exxon. Work at APT shows that
good fine particle removal can only be obtained when using deep beds of fine
granules. Unfortunately, because of entrainment of granules during bed cleaning,
deep fine beds are the most difficult to clean.
Problems and limitations of high temperature and pressure control devices can
be summarized as follows:
Device or Technology
Granular beds
Ceramic filters
Dry scrubbers
Ceramic bags
Electrostatic
precipitators
Major Problems
or Limitation
poor efficiency
difficult to clean
high pressure drop
unknown bag life
unknown operation
Can Meet
13 ng/J?
no
yes
yes
yes
unknown
Use of coal cleaning may also present some future problems in particulate
control. Although the percent ash in the coal will be reduced, the removal of sulfur
gives rise to a high resistivity fly ash as experienced with low sulfur western coals.
Problems with high resistivity ash were noted above. Another potential problem is
that combustion of cleaned coals will produce a very fine particulate emission which
will be difficult to collect because of its size.
EPA has completed work to determine the electrical conduction mechanisms in
fly ash at high temperatures (390° C). Work in this area is being extended to low
temperatures. An outcome of this work has been the demonstration of sodium as a
potential conditioning agent to reduce fly ash resistivity. EPA has evaluated and
published reports on conditioning agents such as SOs and NH3. Conditioning
appears to be a possible solution to retrofit problems, but not for new installations.
Conditioning will not be a solution if it causes adverse environmental effects.
IERL/RTP will conduct further tests to assess the total impact of conditioning. One
test has already been completed; preparation for others is currently in progress.
Specially designed charging or precharging sections are a possible means of
improving the collection of fine high-resistivity particles. A fundamental study and
limited pilot-plant work on particle charging was begun in FY-74. This work was
continued through FY-76 and resulted in a laboratory demonstration of the
feasibility of the concept. A pilot-scale demonstration was funded in FY-77.
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ESP MATHEMATICAL MODEL
ENTRAINMENT SEPARATOR
FABRIC EVALUATION
MOBILE COLLECTORS
A mathematical model for the design of ESP's was completed in FY-75. This
model is in two forms: a design and selection manual for the plant engineer and a
programmed computer version for the design engineer. The model predicts well the
performance of ESP's down to particle sizes approaching 0.01 urn. Programs in
FY-76 and -77 resulted in improvements in this model in the areas of defining the
effects of gas distribution, rapping, and reentrainment.
The major thrust of EPA's scrubber program has been aimed at developing and
demonstrating flux force/condensation (FF/C) scrubbers. In an FF/C scrubber, water
vapor is condensed in the scrubber. When the water vapor condenses, additional
forces and particle growth contribute to particle collection. When the water vapor or
steam is free, FF/C scrubbers are low energy users. However, when water vapor or
steam has to be purchased, FF/C scrubbers require additional energy for efficient
particle collection. Answers to questions of how much steam is needed and how
much is free are major unknowns. Answers to both questions are likely to be source
specific. Thus, pilot demonstrations on a variety of sources are necessary to provide
required data. One pilot demonstration has been completed; a second is underway.
Overall efficiency of a scrubber system is determined by the efficiency of the
scrubber and the efficiency of the entrainment separator. Recent field data indicate
that in some cases inefficient entrainment separator operation is a major cause of
poor fine particle collection by scrubbers. The EPA has recently completed a
systems study of entrainment separators. In FY-76 the design of these separators
was optimized for fine particle control. This design is now ready for demonstration.
Filtration work performed under lERL/RTP's PATB has been aimed at
acquiring information for a two-fold use: incorporation into mathematical models
and addition to the empirical knowledge used by designers and operators for
everyday operation. This work has included studies of fiber property and fabric-type
effects, evaluation of new fabrics, development of mathematical descriptions for
specific parts of the filtration process, characterization of fabric filters in the field,
investigation of electrostatic effects, support of a pilot (and now a demonstration)
program to apply fabric filtration to industrial boilers at a several-fold increase over
normal filtration velocity, studies of cleaning and energy consumption in bag filters,
and a pilot program for control of municipal incinerators.
The fabric filter has recently become important as a control device for utility
boilers burning low sulfur coal; fly ash is very difficult and expensive to control
with ESP's. In FY-77 the EPA funded a demonstration test of a baghouse installed
on a 350 MW boiler burning a low sulfur coal.
Accomplishments of the fabric evaluation program include the following:
• Demonstration of superior filtration performance by spunbonded fabrics,
compared with similar weights of woven fabrics of the same fiber. The
laboratory evaluation justifies field evaluation of this fabric.
• Confirmation of the unique filtering action of one of the classes of
polytetrafluoroethylene (PTFE) laminate fabrics. The fabric filtered fly ash
very effectively, especially for particle sizes in the respirable range (0.01 to
3 m).
• Identification of polyester as suitable for filtering cotton dust.
• Measurement of the performance of uncalendared needled felt fabrics in the
pulse-jet unit and measurement of the endurance of variously coated fibrous
glass fabrics in the high temperature baghouse.
A fleet of mobile conventional collectors that can easily be transported from
source to source and tested has been constructed for use in support of this program.
The fleet includes a mobile fabric filter, a mobile scrubber, and a mobile ESP
unit. These highly versatile mobile units are used to investigate the applicability of
control methods to control fine particulate emitted from a wide range of industrial
333
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MOBILE UNITS
IN OPERATION
TEST RESULTS
sources. Relative capabilities and limitations of these control devices are being
evaluated and documented. This information, supplemented by data from other
IERL/RTP particulate programs, will permit selection of collection systems that are
technically and economically optimum for specific applications.
The mobile fabric filter unit has been operated on effluents from a brass and
bronze foundry, a hot-mix asphalt plant, a coal-fired boiler, a lime kiln, and a pulp
mill recovery boiler. It has also been used to determine the performance of a fabric
filter on air emissions from a cyclone collector used on the St. Louis Refuse
Processing Plant. The filter unit most recently was operated at a Southwest Public
Service Company site to obtain preliminary data for an EPA funded demonstration
of a fabric filter on a 350 MW boiler burning low sulfur coal. The mobile wet
scrubber unit has been operated on a coal-fired power plant, a lime kiln in a pulp
and paper mill, and on a gray iron foundry. The mobile ESP is operating in the
field for the first time, on an industrial boiler burning a mixture of coal and
pelletized refuse. This was used at a field site to evaluate the effects of sodium
conditioning on a low sulfur western coal, and is currently being used on the hot
side of the air preheater at a western power plant to help determine the reasons
behind the failure of hot-side ESP's to perform as well as design would predict
when used to control fly ash from western low sulfur coals.
In the high temperature/pressure particulate control area, bench scale work on
ceramic filters and ceramic bags has shown that the media can survive operating
conditions and provide high collection efficiencies (table 4). As with
aqueous-scrubber results, study results for dry scrubbers prove that they will require
high pressure drops to achieve good fine particle control unless an analog to the
charged droplet scrubber can be developed. The ESP tests have demonstrated stable
corona; however, no efficiency data or projections are available yet.
TABLE 4
Developments in high temperature/pressure particulate control
Completed
to Date
Measured
Efficiency, %
Problems
Conclusions
Ceramic Filters 850 m^/hr tests
Dry Scrubbers Feasibility
Study
Ceramic Bags Screening Tests
Electrostatic Map of Stable
Precipitators Corona
93-100 at 820°C(13> Difficult to clean
sticky particles
90 at 1.0
,(14)
56-90 for felts
using 0.3 M particles
and no filter cake* '
N/A
Efficiency falls
rapidly with decreasing
size
Long term endurance
unproven
Only static tests
with clean plates
to date
Requires in-house tests
on cleaning of more open
geometries
Need to improve submicron
capture efficiency
Requires media development
and life testing
Need to evaluate a flow
system to predict
efficiency
334
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References
1. Hunt, W.F. et al. National Air Quality and Emission Trends Report, 1976,
EPA-450/1-77-002 (NTIS No. PB 279-007), December 1977.
2. National Coal Association, Steam Electric Plant Factors 1976, Washington,
D.C., 1977.
3. Jimeson, R.M. The Demand for Sulfur Control Methods in Electric Power
Generation, Pollution Control and Energy Needs, ACS, Washington, D.C., 1973.
4. Calvert, S. et al. Fine Particle Scrubber Performance Tests, EPA-650/2-74-093
(NTIS No. PB 240-325/AS), October 1974.
5. Nichols, G.B. and J.D. McCain. Particulate Collection Efficiency Measurements
on Three Electrostatic Precipitators, EPA-600/2-75-056 (NTIS No. PB
248-220/AS), October 1975.
6. Drehmel, D.C. and C.H. Gooding. Field Test of a Hot-Side ESP, in
Proceedings: Particulate Collection Problems Using ESP's in the Metallurgical
Industry, EPA-600/2-77-208 (NTIS No. PB 274-017/AS), October 1977.
7. Shannon, I I. et al. Feasibility of Emission Standards Based on Particle Size,
EPA-600/5-74-007 (NTIS No. PB-236-160), March 1974.
8. University of California, Davis, Radiobiology Laboratory Annual Report -
Fiscal Year 1977, UCD 472-124 under Contract EY-76-C-03-0472, Dept. of
Energy.
9. Duncan, L.J. et al. Selected Characteristics of Hazardous Pollutant Emissions,
The Mitre Corporation, May 1973.
10. McKenna, J.D. Applying Fabric Filtration to Coal Fired Industrial Boilers: a
Pilot Scale Investigation, EPA-650/2-74-058a (NTIS No. PB 245-186/AS),
August 1975.
11. Bradway R.M. and R.W. Cass. Fractional Efficiency of a Utility Boiler
Baghouse: Nucla Generating Plant, EPA-600/2-75-013a (NTIS No.
PB246-641/AS), August 1975.
12. EPA, Standards of Performance for New Stationary Sources, 40 CFR Part 60.
13. Drehmel, D.C. and D. Ciliberti. High Temperature Control Using Ceramic
Filters, Paper No. 77-32.4, APCA 70th Annual Meeting, June 20-24, 1977,
Toronto, Ontario, Canada.
14. Calvert, S., R. Patterson, and D. Drehmel. "Fine Particle Collection Efficiency
in the APT Dry Scrubber" in EPA/DOE Symposium on High Temperature
High Pressure Particulate Control, EPA-600/9-78-004, September 1977.
15. Shackleton, M. and J. Kennedy. "Ceramic Fabric Filtration at High
Temperatures and Pressures," in EPA/DOE Symposium on High Temperature
High Pressure Particulate Control, EPA-600/9-78-004, September 1977.
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LIT/
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CONTROL TECHNOLOGY PANEL DISCUSSION
Frank T. Princiotta
Office of Energy, Minerals and Industry
U.S. Environmental Protection Agency
H. William Elder
Emission Control Development Projects
Tennessee Valley Authority
Kurt E. Yeager
Fossil Fuel Power Plant Department
Electric Power Research Institute
John A. Belding, Ph.D.
Energy Technology
Department of Energy
Marvin I. Singer
Environmental and Socio-Economic Impact,
Resource Applications
Department of Energy
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MR. PRIIMCIOTTA: On the basis of what we have heard about sulfur control, we
are going to have to rely for the next 5 or 10 years upon conventional coal
combustion with scrubbers, perhaps supplemented by coal cleaning. Norman Kaplan's
paper presented a relatively optimistic view of the status of the technology. I would
like to ask what our panelists think is the current status of scrubbers or flue gas
desulfurization, and on what problems they think we should focus our research over
the next 5 or 10 years.
MR. ELDER: Mr. Kaplan left us with the impression that this technology was
ready, near-term, and cost-effective. From the utility viewpoint, at this stage we see
it as a potentially viable technology. When it is ready, it will be expensive. The EPA
program in control technology for pilot plant and prototype work has been a good
program. We have learned a lot in the past 10 years about the factors that affect
scrubber operation, particularly the chemistry-related factors. It has, however,
involved fairly small-scale research testing, which does not face up to the real
problems of reliability. At the current stage of scrubber development the problems
with reliability are more mechanical factors than process factors.
Mr. Kaplan mentioned plugging and scaling as the problem areas. These are
related primarily to how we react the limestone, lime, or sodium, the S02 and the
flue gas. What is the variability of the SO2 in the gas? What is the variability in the
absorbent or the raw materials used? We have fairly good understanding of these
process questions now. If we can control the inputs to the scrubber system, we can
avoid these problems rather well. What we do not yet know enough about is the
mechanical design of many of the components, such as dampers, pumps, and
valves—components that control flow of both gas and liquid in the absorber itself.
These are the areas that we need to concentrate on to improve reliability so that we
can design a system and expect it to operate at the designed conditions.
In regard to cost, Mr. Kaplan told you that fuel gas desulfurization (FGD)
would add 10 to 20 percent to the cost of power generation. I think those numbers
are based on a new plant at maximum capacity. The numbers we have developed
show that the net increase in cost is about 20 to 25 percent if we take into
account the full-term life of the scrubber installed in a new power plant. For
retrofit, to build a scrubber in an already existing plant, it becomes even worse. It
can double that number. For example, in one of our TVA systems, an existing 500
megawatt plant has been equipped with scrubbers. At that single plant the cost for
generation of power has gone up 50 percent. But it was a retrofit, and the
investment had to be amortized over a short period. All these things influence the
percentages that are shown in cost estimates.
MR. YEAGER: At the present time, in scrubber technology application in utilities
we need a site-specific design basis. Our ability to predict, design, build, and operate
a plant by current scrubber technology with predictable results is very poor.
Although I appreciate Mr. Kaplan's curve on the improvement and availability, from
the same data we have not been able to derive the same kind of relationship. We
have found very little change in the performance of scrubber systems that have been
put in over the last 5 years. In the high-sulfur eastern coal region, those systems
that have worked well from an availability standpoint benefit from having a load
factor which permits continuous maintenance and cleaning of some portion of the
scrubber system at all times and an unrestricted maintenance requirement on the
part of the particular utility. We do not feel, therefore, that this is the solution to
the problem. This is not to indict scrubbers; it is simply a statement about our
current technology and where it should be going.
Given the regulatory direction in terms of air and by-product disposal,
by-product disposal problems will become increasingly important, so a second major
objective is to avoid sludge production, whether it be gypsum as a dry by-product,
sulfur, or sulfuric acid. Most importantly, it will mean a retrofit capability to
systems which are going in now, almost all of which produce sludge, to avoid the
necessity within 5 to 10 years of ripping out all the hardware and replacing it with
something new.
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The third item on the development agenda is a realistic ability to produce
elemental sulfur. By realistic, I mean one which does not require reducing natural
gas or putting a coal gasifier on the scrubber. Elemental sulfur is certainly not the
product we would propose for all portions of the country, but certainly, in many
areas of the east, the land, environmental, and market requirements will drive
people in that direction.
DR. BELDIIMG: Previous speakers have talked about reliability, solid waste, and cost.
They are important. But it may require a combination of coal cleaning and scrubbers
to solve the problem. I am not convinced that we can lay the whole responsibility
on scrubbers. We have to look at a combination of things in the future. We have to
scale up and look at reliability and cost. We need to look at the whole system.
MR. PRINCIOTTA: Obviously, there are problems with flue gas desulfurization
systems. In view of that, which of the emerging energy -technologies—such as
fluidized-bed combustion, solid refined coal, low Btu gasification, or chemical coal
cleaning—is most likely to displace conventional pulverized coal technology with
scrubbers, and in what time frame?
MR. SINGER: The Department of Energy is taking quite an aggressive approach to
the commercialization of these emerging technologies. It is too early to say which
technology might replace scrubbers, but we have formed about 14 task forces within
the Department to look at the different emerging technologies. The task forces are
just beginning to get some preliminary indications of the readiness of each of the
technologies for commercialization.
I am personally participating in the coal liquids technology. There has been
some indication of user interest in coal liquids. We foresee the first application of
these products for electric power generation in the 1990's. We expect to be working
over the summer to develop a marketing plan for the commercialization of the
technology. All the task forces will be doing much the same thing.
DR. BELDING: The Department of Energy is looking at a variety of technologies.
In addition to the atmospheric fluidized bed and the pressurized fluidized bed, we
are also looking at combined cycle systems, which have the potential of being fairly
efficient, low-cost machines.
*
I do not think the Department is going to decide which technologies are
viable; it will, instead, be the user. We have to look at the economics. Can we, in
fact, meet the EPA requirements? Can we do better than the requirements? These
are questions that users will be interested in. Mr. Yeager and Mr. Elder can address
these questions better than we in the Government can, because they will be buying
the machines. They would like a variety of products to choose from, to foster
competition and, perhaps, lower some of the current rates.
MR. YEAGER: On a national basis, with the uncertainties of economic and
environmental considerations, we probably cannot afford not to develop all the
options we have. From the utility standpoint, liquids, as a probable retrofit fuel for
oil-based capacity, as well as peaking fuel, are going to be important contributors to
the industry at some future time. When we look at options for base load capacity,
however, we start having some problems.
Pursuant to Dr. Belding's comments in the environmental area, let me add one
comment. We are qualitatively changing our environmental definition and specifica-
tions concerning what we consider "clean." In the past we considered technologies
clean because of the low sulfur content or low sulfur oxide emissions. With the
introduction of toxics requirements, however, such as a very stringent NOX
restriction, the technologies need to be re-examined. While the requirements can
generally be met, the economic relationships change considerably. Technologies such
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as gasification combined-cycle processes seem to, and may actually, be competitive
with or superior to conventional plants from an economic and environmental
standpoint. We must now re-examine the economics in terms of what it takes to
totally isolate any toxic emissions from the environment. Great interest has been
shown in fluidized-bed combustion, particularly AFBC, both because of its relative
simplicity and because of its ability to burn a variety of fuels, solving what is a real
industrial problem as coal sources change considerably over the lifetime of a plant
AFBC offers the opportunity to solve the problem, but whereas AFBC was, at one
point, capable of meeting all the environmental requirements of the combustor, we
now have to re-examine the designs in light of more stringent S02 and NOx
requirements. This, again, affects the practicality of the technology of the industry.
As environmental specifications become more important in our social environment,
we must be able to forecast the requirements to the engineers so they can be
considered during the development phase and not as an afterthought.
MR. ELDER: Taking a realistic view of the scrubber situation, if low-sulfur coal in
the east is not a viable option, it is clear that fuel gas desulfurization is the way to
go for the near-term, at least 10 to 15 years. That means a lot of scrubbers are
going to be built. There is a lot of incentive for getting that technology to the
point where it is productive. We must develop conversion alternatives as quickly as
possible so we can ascertain the costs. Although many interesting estimates have
been made, they are not yet very informative, and they will not be until we build
some full-scale systems and find out what the real costs are. Then we will have an
idea of what oil and gas will really be worth to us in the future.
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questions
at answers
Dr. J. M. Colten
Appollo Chemical
Herbert H. Braden
Research-Cottrell, Inc.
A. Saleem
Envirotech/Chemico
Dr. Rudolf Husar
Washington University
Bob Kaper
Coal Daily
H. Burt Spencer
Joy Manufacturing Company
Dr. Edward S. Rubin
Carnegie-Mellon University
George Wiedersum
Philadelphia Electric Company
QUESTION
One way to improve the performance of electro-
static precipitators is by flue gas conditioning or
improving the resistivity of properties of flue gas. Over
10,000 megawatts of capacity utilize this technology
and the effect on resistivity has been the major reason
for that utilization. Recently, there has been some
indication that we can affect the factor we are most
concerned with: We can increase the particle size
distribution. What does Research Triangle Park think?
RESPONSE: Dr. Dennis C. Drehmel (EPA)
We have an active conditioning-agent program.
Both 863 and sodium carbonate are effective condition-
ing agents. They restore efficiency through a precipitator
on a power plant by changing high sulfur coal to low
sulfur coal. Unfortunately, our results are mixed and we
have problems: Perhaps only three-fourths of the
previous capability is returned by the use of condition-
ing agents or the agents plug up various parts of the
boiler. We have had problems with other compounds,
precursors or nitrosamines, being formed in laboratory
tests on conditioning agents. For the entire story, we
need to know what environmental impacts are associated
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with conditioning agents, even with 503. The overall
logic of control strategy has to be questioned. If a low
sulfur coal is used to lower the S02 which, presumably,
is there to reduce sulfates, and an 503 agent, which
adds back 804, is introduced, sulfates are put back.
What is the tradeoff on this?
QUESTION
Are the benefits of precombustion desulfurization
taken into consideration in the definition of compliance,
compliance being 85-percent or 90-percent?
RESPONSE: Mr. Frank T. Princiotta (EPA)
The Clean Air Amendments are quite specific.
They indicate that in any percentage, EPA should take
into account reduction standards such as the 85-percent
sulfur dioxide standard. This includes any precleaning,
so that coal cleaning or any other cleaning approach
would not be precluded by the standard. It would be
counted within the overall percentage removal. In other
words, the percentage is counted from the mined coal
all the way to the sulfur that ends up in the flue gas.
QUESTION
Similarly designed FGD systems were installed in
Japan and in the United States, but their performance
has not been equivalent. In evaluating the systems, what
significant factors have been noted?
RESPONSE: Mr. H. William Elder (Tennesse Valley
Authority)
Technical reasons make the situation in Japan
different from that in the United States. First, most of
the FGD in Japan is by oil-fired generating capacity,
and oil-fired capacity design conditions are very close to
the operating condition. The designer knows in advance
what the emitted SC>2 concentration is. He designs the
system to handle that concentration. SC>2 concentration
with oil is much lower than with coal so that the range
of operating conditions in the design is different in
Japan from that in the United States. The second point
is political rather than technical. In Japan, almost
without exception, the installed FGD systems have
monitoring equipment that telemeters the outlet con-
centrations directly into the environmental group in the
local prefecture or state. They know immediately when
a system is not in compliance and crack down on the
utility. As a result, we visited several installations that
had no violations for a period of 3 to 5 years. Their
enforcement mechanism is rigorous.
QUESTION:
What was your reaction to coal-fired facilities in
Japan?
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RESPONSE: Mr. Elder
Surprisingly, their average for the sulfur content of
coal is 0.7 percent. The sulfur level in the feed stream
for the scrubber is normally less than 1/10 variation. To
keep that low variability, they are careful about
blending and/or selection of the fuel. The system is
treated as a chemical plant. There is no redundancy in
installed gas equipment or, on the liquid side, in pumps
and spare trains and spare modules. Although a little
incriminating to the utility industry, a company sub-
sidiary to the utility company usually operates their
scrubbing systems. Japanese companies are large and
have many subsidiary companies. They therefore can
assume the liability for the control system and farm out
its operation to a chemical company that is part of the
overall group. They have, therefore, paid more attention
to process control than the United States has.
QUESTION:
Are there any additional comments?
RESPONSE: Mr. Norman Kaplan (EPA)
Of the 10 systems visited in Japan, the majority
were getting 90-percent or more S02 removal, with
98-percent availability. At the end of 1977, we have
131 units plus several industrial boiler units, adding up
to less than 200 units. Japan has 500 FGD plants. They
total 28,000 megawatts—almost three times as much as
ours—that are divided 50-50 between utilities and
industrial boilers. The only way to determine whether
costs are high or low is to compare them with the
potential or the real health benefits to our population.
Until better information is available from the health
benefits people, we cannot make a judgment about our
costs. I do not feel that they are high.
Retrofit systems usually cost more than new
systems, but when observing new source performance
standards, we mean new systems and increased costs for
new systems.
The systems in Japan are more dependable. In the
United States, we find that where no bypass of the flue
gas desulfurization system is allowed, the flue gas
desulfurization system is more reliable or more depend-
able. We can almost legislate the dependability of a flue
gas desulfurization system. Another item on depend-
ability is redundancy. At a little higher cost, systems
can be designed with redundancy to improve the
reliability of the system as is commonly done in the
chemical industry. A pump critically required to be in
operation all the time is spared. If the pump has a
problem, a switch is pushed and the pump goes off
while another comes on. Many of the critical com-
ponents, including the scrubber, can be designed with a
certain amount of redundancy. There are answers to the
problem.
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QUESTION
For sulfur control, the current emphasis is on
sulfur dioxide. This is because sulfur dioxide control
also reduces the sulfate in the atmosphere. In addition
to the sulfur dioxide removal, suppose there are
alternative methods of reducing sulfate, namely, chang-
ing the effective stack height or changing the seasonal
pattern of the emission. Will the Clean Air Amendment
benefit methods other than direct emission control of
sulfur dioxide?
RESPONSE: Mr. Princiotta
A very careful reading of the Clean Air Amend-
ments shows that they are aimed primarily at direct
emission control. There is no leeway for any dilution
approaches, such as extending the height of the stack.
Right now the pollutant that is regulated is sulfur
dioxide. We have an ambient air quality standard for
S02 but we do not, as yet, have a specific standard for
sulfates. If that happens, there may be changes in the
regulatory approach to the control of that particular
pollutant.
QUESTION
When the hazardous waste regulations are finally
promulgated, a certain amount of fly ash and scrubber
sludge is probably going to be classified hazardous. What
happens with disposal ponds, like the Bruce Mansfield
sludge pond, already in existence? Assuming it is not in
a hazardous disposal site, suppose that were declared
hazardous. What should be done?
RESPONSE: Mr. Princiotta
As I understand the hazardous waste regulation,
assessment of the inherent hazardous nature of waste is
independent of how it might be controlled. For
example, disposal of waste in a pond would not
necessarily be related to whether or not the waste is
hazardous. Those variables are separate. There are two
separate regulations, as I understand: one to define what
the hazardous waste is, and the other, if the waste is
hazardous, to determine the most appropriate way to
control that waste.
QUESTION
Dry lime scrubbing systems based on the use of
spray dryers have recently been tested; they can reach
reasonable efficiencies and produce a dry paniculate
when scrubbing flue gas for sulfur removal. Are there
comments on this new type of system?
346
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RESPONSE: Mr. Kurt E. Yeager (Electric Power
Research Institute)
Several of them are being installed now in the
western United States. We hope that they will be a
practical alternative. The experience shows that the dry
removal mode may be limited in some of the high
sulfur applications, although to resolve that there is
considerable development work to be done. The usable
removal material has typically been a sodium-based
by-product. Will the hazardous substance regulations put
unrealistic limitations on the disposal of those kinds of
by-products?
QUESTION
Since last fa/1, a large number of coal cleaning
plants on the East Coast have tried to come into
operation but have been prevented on PSD basis. Those
plants with thermal dryers have had a hard time
meeting the PSD increments. Are we paying adequate
attention to control technologies for coal preparation
plants, specifically to alternative types of dewatering
devices, and will this be yet another impediment to this
technology?
RESPONSE: Mr. James D. Kilgroe (EPA)
We are working on the environmental assessment
of coal cleaning technologies and are investigating new
technologies to control pollution from coal preparation
plants. We are in the early phases. Our earlier work on
coal cleaning has concentrated primarily on coal cleaning
for removal of sulfur from coal as an emission control.
A lot needs to be done; in fact, the Effluents
Guidelines Divisions are under court mandate to
examine coal preparation and mining. They are studying
129 varieties of pollutants, and the results are just now
becoming available. With those studies and others on
different coal preparation plants, we might be able to
determine the kinds of new costs to add to coal
preparation costs when considering an SO2 emission
control technology.
QUESTION
On another trip to Japan, there was a difference
of opinion as to whether Japanese FGD systems
achieved closed loop operation. Would the participants
comment on whether they are achieving this?
RESPONSE: Mr. Elder
They are not closed loop. As a matter of
comparing one process with another, the Japanese go to
great lengths to calculate the extent of the open loop.
The liquid blowdown from the scrubbing system,
however, is treated in waste water treatment facilities
before it is discharged into the sea. Suspended solids,
pH, and oxygen demand are controlled, but a significant
amount of water is blown down from the system to
allow freshwater makeup for keeping the surfaces clean.
They are admittedly open loop; that question has been
resolved.
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integrated technology
assessment
chapter 6
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CHAPTER CONTENTS
integrated technology assessment
INTEGRATED TECHNOLOGY ASSESSMENT OF ELECTRIC UTILITY SYSTEMS
Peter M. Cukor, Ph.D., Teknekron, Inc
David B. Large, Teknekron, Inc
Brand L. Niemann, Teknekron, Inc
Andrew J. Van Horn, Teknekron, Inc oeo
Lowell F. Smith, US EPA 353
TECHNOLOGY ASSESSMENT OF WESTERN ENERGY RESOURCE
DEVELOPMENT
Irvin L. White, Ph.D., University of Oklahoma 371
QUESTIONS & ANSWERS
381
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INTEGRATED TECHNOLOGY
ASSESSMENT
INTEGRATED ASSESSMENT OF ELECTRIC UTILITY SYSTEMS
Peter M. Cukor, Ph.D.
David B. Large,
Brand L. Niemann,
Andrew J. Van Horn
Teknekron, Inc.
Lowell F. Smith
Office of Energy, Minerals and Industry
U.S. Environmental Protection Agency
INTEGRATED ASSESSMENT
As a significant energy supplier, consumer of primary fuels, and producer of
wastes and emissions to air, water, and land, the electric utility industry through its
investment and operating decisions influences the nation's economy and the
environment. In turn, the utilities' decisions are influenced by various factors:
government energy and environmental policies, economic conditions, and
technological considerations. Teknekron has developed a framework for assessing in
an integrated manner the impact of these factors on the future investment and
operating decisions made by utility firms. Figure 1 shows that the growth and
development of the U.S. electric utility industry will be influenced by regulatory
constraints, electricity demand, the costs and availability of technologies for
electricity generation and pollution control, and conditions in the nation's economy.
Utility investment and operating decisions, in turn, will be reflected in revenue
requirements, which determine electricity prices, and in fuel consumption, which
leads to releases of air and water pollutants and to the generation of solid wastes.
REGULATORY CONSTRAINTS
ENVIRON-
MENTAL
IMPACTS
ELECTRICITY
PRICES
ELECTRIC UTILITY
INVESTMENT AND
OPERATING DECISIONS
PRESENT AND
PROJECTED
POWER
DEMANDS
POLLUTION
CONTROL
COSTS
TECHNICAL
AND
ECONOMIC
CONDITIONS
FIGURE 1—Integrated assessment process
353
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O ATTAINMENT OF AIR QUALITY
• SIP
O MAINTENANCE OF AIR QUALITY
• SIP REVISION
• EMISSION OFFSETS
• SITING RESTRICTIONS
• NEW SOURCE PERFORMANCE STANDARDS
• BEST AVAILABLE CONTROL TECHNOLOGY
O PREVENTION OF SIGNIFICANT DETERIORATION
• SITING RESTRICTIONS
• EMISSION OFFSETS
• BEST AVAILABLE CONTROL TECHNOLOGY
FIGURE 2-Air pollution control goals and policy tools
ONE MAJOR FOCUS
UTILITY SIMULATION MODEL
One major focus of this integrated assessment has been to analyze the regional
air quality impacts of the decisions utilities are likely to make in response to
alternative energy and environmental policies and economic and technical conditions.
For each set of alternatives, we have determined the probable air quality impacts
first by forecasting the spatial distribution of power-plant emissions (by county) and
then by applying statistical analyses of historical meteorological data and air
transport models. Several of the results obtained so far have profound implications
for the EPA in terms of the Agency's meeting the requirements of the Clean Air
Act as amended in 1977.
Figure 2 shows three of the most important goals of the Clean Air Act.
Teknekron's electric utility integrated assessment has focused on evaluating the
economic and environmental implications of several alternative policies EPA might
adopt to achieve these goals. Listed in figure 2 are some of the policy tools
available to the Agency.
The integrated assessment process depends on Teknekron's Utility Simulation
Model (USM), which consists of interconnecting computer modules and data bases
that simulate decisions for system planning and operation, utility finance, and the
operation of individual technical processes such as pollution control devices. The
model is driven by a set of exogenous scenario elements that include electricity
demand levels, financial market conditions, fuel prices and availabilities, advanced
technology deployment, and environmental regulations. For each scenario, the model
calculates the following by geographical region, for each county or state, for future
years up to 2010:
• Factor demands, including
• fuel use, by type and by region of origin
• electricity generated, by type of unit and for individual units
• capital requirements, by source (e.g., debt, comrnon equity, preferred
equity)
• plant and equipment requirements
• releases of air and water pollutants and generation of solid wastes, by
county
• Financial statistics for utility firms
• Average electricity prices
354
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DEMAND
PLANNING
DISPATCH
PATCH •••M
FINANCIAL
RESIDUALS
REGIONAL AIR QUALITY ANALYSIS
FIGURE 3—Teknekron utility simulation model
GENERATING-UNIT SITES
USM MAJOR COMPONENTS
In order to produce these calculations at the required level of detail, the
model considers generating-unit sites located in each county in the 48 contiguous
states where electricity is produced, fuel and water are consumed, and pollutants are
released. Since utilities operate as integrated systems, the model presently simulates
the joint operation (i.e., dispatching) of generating units owned by utilities within a
state. Finally, the responses of utility firms to the external environment in which
they function may be changed by the model user by modifying present data bases
or by specifying alternate choices for future system planning operation. For
example, the particular scenarios evaluated in Teknekron's review of alternative New
Source Performance Standards encompass a range of futures for electricity demand,
fuel selection, technology choices, and pollution control regulations specified by the
EPA. Some results of that analysis will be presented in the following section.
Figure 3 is a simplified diagram of the USM. The model includes the following
major components:
• Demand projection by year, including
• retail and wholesale sales and purchases
• energy generation (i.e., average load growth)
• peak load growth
• System planning projection by year, including
choice of generating-unit type
choice of fuel type, quality, and coal region of origin
choice of pollution control technology
expansion of transmission and distribution networks
siting of generating units by county
• Dispatch seasonally for typical days, including
• calculation of unit capacity factors for each typical day of operation, by
class of unit
• calculation of total fuel, operation, and maintenance expenses for
electricity generation
• projection of fuel consumption, by type and region of origin
• calculation of pollution control costs and operating characteristics for the
various types of pollution control devices
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FINANCIAL
CONSIDERATIONS
• Financial considerations by year, including
• integration of projected production expenses with construction
expenditures
• projection of the firm's balance sheet, income statement, sources and
uses of funds, and other financial statistics
• calculation of revenue requirements and electricity prices
• Residuals released and resources consumed, including
• projection of release rates at the generating-unit site for numerous air
and water pollutants and for solid wastes
• projection of consumption of water and other resources
• Regional air quality analyses, including
• forecasts of the counties that will have high emissions from utility and
industrial boilers
• analysis of historical meteorolgical data to yield preferred paths for the
downwind transport of emissions from source locations
• analysis of emissions, air quality, and meteorological data to develop
source-receptor relationships for S02 emissions and sulfate concentrations
• application of air quality models to determine ambient concentrations of
SC>2, NOX, particulates, and sulfates
USM PROJECTS COSTS
DISPATCH MODULE
RESIDUALS MODULE
A number of detailed data bases—including data on each installed and announced
generating unit in the U.S., financial and operating statistics submitted by utilities to
the former Federal Power Commission, and fuels data—provide inputs to the major
components of the model.
The USM is not a linear program that seeks to minimize the national cost of
producing electricity. Rather, it projects year-by-year investments, operating costs,
fuel usage, and pollutant releases, making maximum use of data sets that reflect the
current condition and composition of utility systems, using 10-and 20-year
projections made by individual utility firms, and reflecting the factors influencing
utility decision makers in their current and future choices.
In response to an exogenously specified forecast of demand, the System
Planning module builds new capacity consistent with the announced plans of utility
firms modified to reflect specified reserve requirements. For coal-fired capacity, the
Assign module reviews delivered prices and pollution control costs for 18 different
coal types and selects that combination of coal supply source and pollution control
equipment that results in compliance with state and federal air pollution control
regulations at least cost. The Planning module also effects announced plans for fuel
conversion and plant retirement and calculates capital investment requirements for
each year of simulation. Investment needs serve as one input to the Financial
module.
The Dispatch module reviews the operating costs for the available generating
capacity and apportions the electrical load so that the total system cost of
producing electricity is minimized for the system of existing plants and new plants
built by the Planning module. Thus, the Dispatch module makes it possible to
calculate both fuel consumption by category of plant and total system operating
costs. Operating costs are input to the Financial module, while fuel consumption
results are passed on to the Residuals module.
The Residuals module calculates releases of air and lan
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FINANCIAL MODULE
KEY ANALYTICAL TOOL
BASELINE PROJECTIONS
impacts here we mean, for example, the distribution of price increases and pollutant
reductions arising from pollution control regulations, shifts in the market for coals
from different supply regions, and the existence of high-emission areas that can lead
to deterioration of regional air quality.
The Financial module performs annual updates of the base-year income
statement and balance sheet for the utility firms merged at the state level. Needs for
external financing to accommodate the investment requirements forecast by the
Planning module, as well as the cost of this financing, are calculated by source of
capital. Average prices for each succeeding year are calculated considering all costs
of operation, including o return on the rate base. Separate treatment is provided for
investor-owned and non-investor-owned utilities in each state because of their
different financial status.
How have these tools developed by EPA's Office Of Research and
Development been applied in support of the Agency's programs? Three important
applications of the models, data bases, and analytical techniques developed in this
integrated assessment have been (1) to quantify the impacts of revised New Source
Performance Standards (NSPS) requiring Best Available Control Technology (BACT),
(2) to identify local air quality problem areas, and (3) to determine the extent of
the need for regional, rather than national, environmental policies (figure 4). In the
remainder of this discussion, we review each of these applications in turn.
In response to a petition by the Sierra Club and to Section 111 of the Clean
Air Act as amended in 1977, EPA's Office of Air Quality Planning and Standards
(OAQPS) is investigating alternatives for revising the New Source Performance
Standards for emissions of S02 and particulate matter from coal-fired utility boilers.
Teknekron's Utility Simulation Model is the key analytical tool being used by
OAQPS to investigate the regional, economic, and environmental impacts of revisions
specified by EPA.
The impacts of alternative policies are most effectively revealed through
comparison with baseline projections of the impacts of continuing with current
policies. The baseline projections developed in our NSPS evaluation take into
account many elements of current national and subnational environmental policies,
including the curtailment and phasing out of natural gas as an electric utility boiler
fuel, the coal conversion program under ESECA, siting restrictions in Class I or
nonattainment areas, retrofitting of cooling towers and other required pollution
control measures, and compliance with current State Implementation Plan (SIP) and
New Source Performance Standards for SO2, NOX, and particulates.
O IMPACTS OF REVISED NSPS (BACT)
• EMISSION REDUCTIONS
• ELECTRICITY PRICES
• REGIONAL COAL DEMAND
• SPATIAL DISTRIBUTION OF EMISSIONS
O IDENTIFICATION OF LOCAL PROBLEM AREAS
• THE NEED TO CONTROL EXISTING PLANTS
O THE NEED FOR REGIONAL POLICIES
FIGURE 4-7T/4 applications
357
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EMISSION STANDARDS
ASSUMED
CAPACITY MIX
For the analysis of alternative NSPS revisions, the following emission standards
were assumed to apply:
• For generating units on line prior to 1977: SIP limits
• For generating units on line between 1977 and 1982: current NSPS
• For generating units on line after 1982: revised NSPS
The SIP limits vary by state and county. Current NSPS for emissions from coal-fired
boilers are 516 ng/J (1.2 lb/106 Btu) for S02, 43.0 ng/J (0.10 lb/106 Btu) for
particulates and 301 ng/J (0.7 lb/106 Btu) for NOX. Among the several possible
S02 options we evaluated was adoption of a standard stipulating Best Available
Control Technology (BACT), which implies the use of flue gas desulfurization, and
90 percent mandatory post-combustion S02 removal with an upper limit on
emissions of 1.2 lb/106 Btu. The baseline case, continuation of the current NSPS,
involves no mandatory percentage post-combustion SO2 removal. For particulates, we
considered a revised NSPS of 12.9 ng/J (0.03 lb/106 Btu). Other NSPS alternatives
were included in the analysis but, because of space limitations, are not presented
here. Furthermore, the results given here include only those obtained under the
"high demand" case—that is, under the assumption that growth in electricity demand
will be 5.8 percent per year nationally until 1985 and 5.5 percent per year
thereafter.
Table 1 shows the capacity mix for the U.S. electric utility system in 1976
and in 1995 under two nominal projections of growth in electricity demand. The
simulation model projects capacity additions for the investor-owned and
publicly-owned sectors by year and by state, at the county level. For each year the
model also simulates a least-cost dispatch of the available units in each state to meet
the projected load curves for typical weekdays and weekend days in each of the
summer and winter seasons. The shapes of the load curves can be varied to examine
the effects of different rates of growth in peak and average electricity demand.
However, for the NSPS review, peak and average loads were assumed to grow at the
same rate, leaving the shape of the load curves unchanged.
TABLE 1
U.S. electric utility system
1976 Capacity
Capacity Type (GW)
Nuclear
Coal
Oil
Gas
Combined Cycle
Hydro
Turbines
Geothermal
40.5
196.9
87.3
60.3
1.2
67.6
45.7
0.3
1995 Capacity (GW)
Moderate High
Growth ~ Growth"
314.4
411.5
119.0
5.5
17.6
100.3
115.4
3.6
328.5
568.8
119.7
5.5
23.3
109.4
124.7
4.6
EMISSION REDUCTIONS
Total (GW)
509.
1088.
1285.
"Capacity mix varies with scenario.
One benefit of revising the NSPS will come from substantially reduced S02
emissions. The reduction in S02 emissions (assuming high growth of electricity
demand) is illustrated in figure 5 by the difference between the top curve (current
NSPS) and the middle curve (revised NSPS with 90 percent S02 removal). The
revised SO2 standards will have the greatest relative impact in those regions that do
not presently have a large base of coal-fired generation: compared with current
standards, the revised NSPS will reduce emissions by 56 percent in the West South
Central region, by 53 percent in the North Mountain region, by 47 percent in the
South Mountain region, by 42 percent in the Pacific region, and by 23 percent in
358
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CURRENT NSPS
BACT 90% REMOVAL)
27.6
19.0
13.9
MORE STRINGENT SIPs
PLUS BACT
1975 1980
1985 1990 1995
YEAR
2000
FIGURE 5—National power-plant SC>2 emissions under alternative control scenarios, high
growth
PARTICULATE EMISSION
REDUCTIONS
the New England region. The spatial distribution of these percentage emission
reductions is indicated by the darkest areas in figure 6. In terms of reduced S02
emission tonnages, the West South Central, East North Central, and South Atlantic
regions will have the largest reductions. However, even with the imposition of BACT
and a standard of 90 percent S02 removal, national SO2 emissions will increase over
the 1976 level as a result of added coal capacity and the continued utilization of
existing plants covered by SIP regulations. If all SIPs that now allow S02 emissions
to exceed 2.0 lb/106 Btu were changed to permit no more than that amount,
national S02 emissions in 2000 could be kept at roughly 1976 levels, as indicated
by the lowest curve in figure 5. Later we shall show that the imposition of tighter
SIPs would have the most dramatic impact on SO2 emissions in the eastern third of
the nation.
As for particulates, total emissions nationally under current standards will
increase only slightly above the 1980 full-compliance level and will grow slightly in
the 1990s. Revising the NSPS for particulates downward from 43 ng/J (0.10 lb/106
Btu) to 12.9 ng/J (0.03 lb/106 Btu) will reduce national aggregate emissions by 11
percent in 1990 and by 22 percent in the year 2000. Paniculate emissions from
units coming on line after 1982 will be reduced even more, which may have
important local impacts. Finally, emissions of NOX from electric power generation
will increase substantially under current standards, even under an effective
conservation program to curb electricity demand. Under high demand, NOX will
increase from 5.7 million metric tons in 1980 to 15.6 million metric tons in 2000;
under moderate growth, NOX will increase to 8.6 million metric tons in 2000.
359
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-100% to -75%
-75% to -50%
-50% to -25%
-25% to 0%
0% to +25%
+25% to 100%
0 under One
or Both Cases
No Change
FIGURE ^-Percentage change in SOj emissions in year 2000 (BACT with respect to current NSPS)
TABLE 2
National economic impacts of revised NSPS (1975 dollars)
1995 Retail Price (C/kWh)
1995 Per Capita cost
Pollution control costs
Baseline
(Current Standard)
3.10
$685
$40
Revised NSPS
(90% S02 Removal)
3.23
+$27*
+$16*
Percent
Change
+4.2
+3.9
+41
(1986-1995, 1()9$)
Pollution Control Investment
(1986-1995, 109$) $18
Total Investment, Excluding
Pollution Control
(1986-1995, 109$) $519
+$34*
+$5.5*
+ 195
+1.1
*Change from Baseline.
FINANCIAL IMPACTS
Who will pay for the benefits of reduced emissions? NSPS revisions will have
regional economic and financial impacts and will increase national pollution control
costs. Between 1986 and 1995, pollution control costs under the 90 percent S02
removal standard will be 41 percent higher than under the current standard.
However, since pollution control costs represent a relatively small fraction of
electricity costs, the revised standard in 1995 will result in an electricity price
increase of only about 5 percent. A detailed breakdown of yearly costs, balance
sheets, and other financial statistics are calculated by state in the financial module
of the USM. National results for the baseline and the 90-percent-removal standard
are given in table 2.
360
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TABLE 3
Regional price impacts of a proposed NSPS revision
REGIONAL COAL DEMAND
SCRUBBERS FOR SO2
CONTROL
Nation
Region
West South Central
North Mountain
West North Central
East North Central
South Atlantic
East South Central
Mid Atlantic
South Mountain
Pacific
New England
Baseline Value
(C/kWh)*
3.1
2.9
2.3
3.0
3.3
3.3
1.4
3.8
2.9
2.9
4.3
Percent Increase in
1995 With Revision**
+ 4.2
+ 12
+ 7.4
+ 5.4
+ 4.8
+ 4.6
+ 2.8
+ 2.1
+ 1.7
+ 1.0
+ 0.2
*Average for all retail customers, measured in 1975 dollars.
**Mandatory FGD on all post-1982 plants; particulate limit reduced.
The regional price impacts of revising the NSPS to include 90 percent SO2
removal and a lower particulate limit are shown in table 3. These regional
percentage price increases are influenced by the amount of anticipated coal capacity
relative to current coal capacity, particularly in the West South Central states (now
dependent on natural gas for electricity generation) and in the Mountain states
(where coal resources are rapidly being developed). In New England, for example,
the continued dependence on nuclear generation and the distance from coal supply
sources will prevent substantial increases in coal-fired capacity and hence in the
relative costs of stricter SO2 controls.
Coal consumption will be significantly influenced by the growth rate in
electricity demand after 1985. Figure 7 illustrates national coal consumption in
metric tons under a high post-1985 growth rate of 5.5 percent per year and under a
moderate growth rate of 3.4 percent per year. The projection is based on currently
announced utility plans for installing coal plants and on the operation of these
plants projected by the Utility Simulation Model. National Energy Plan goals for
1985 coal consumption may be achieved by the electric utility sector, which now
consumes two-thirds of the coal produced nationwide. It will be difficult, however,
for the industrial use of coal to expand as rapidly.
Alternative New Source Performance Standards will have a significant impact
on the use of local coals and on the markets for western coals. Our analysis suggests
that the consumption of Powder River Basin coal after 1985 may change
substantially under a standard requiring 90 percent removal of S02 (figure 8).
The USM projects the needed requirements for flue gas desulfurization (FGD)
devices in order to meet specified emission limits. For the case of high growth in
electricity demand, scrubbers will be used in 1995 to clean roughly 355 GW of coal
capacity under a standard requiring 90 percent post-combustion SC>2 removal but for
only about 80 GW under continuation of the current standard. The regions of the
country with the highest installed scrubber capacities by 1995 under the revised
standard will be the West South Central region (84 GW), the East North Central
region (82 GW), and the South Atlantic region (76 GW). These three regions will
contain 60 percent of the total installed FGD capacity in that year.
Table 4 illustrates the projected amounts of sludge produced and water
consumed by FGD systems under the two S02 standards. Approximately 3.8
percent of the primary coal energy will be required to operate FGD scrubbers in
1995 under the 90-percent-removal standard.
The Utility Simulation Model has been used to identify counties that will have
high pollutant emissions in the future. By combining data on emissions and
361
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800-
600-
400-
1650
HIGH GROWTH
MODERATE GROWTH
390
4
1975
1980
1985 1990
YEAR
FIGURE 7—Projections of electric utility coal consumption
1995
2000
FIVE GEOGRAPHIC SCALES
OHIO RIVER BASIN STUDY
meteorology with air quality analyses, we have determined the areas where regional
studies are required and have identified subregional and local problem areas as well.
Our air quality impact analyses are over five geographic scales: subnational
(e.g., the eastern United States), regional (the six-state Ohio River Basin area),
subregional (the Lower Basin area), local (the portion of the Lower Basin between
Louisville, Kentucky, and Cincinnati, Ohio), and site-specific (specific power plants).
The approach has been to prepare the emissions, air quality, and meteorological data
bases for each of these five scales and to conduct an integrated analysis as a
necessary prelude to performing air quality impact predictions using dispersion
models. We illustrate this approach by describing some results from our analyses of
the Lower Ohio River Basin.
Early in the integrated assessment, Teknekron identified the Lower Ohio River
Basin, particularly the area from Cincinnati to Louisville, as one of the most
prominent air quality problem areas. Coincidentally, concerns of local citizen groups
over the potential concentration of coal-fired power plants in this area provided the
impetus for another major OEM I program, the Ohio River Basin Energy Study. In
the Teknekron work, the focus has been in determining the local and medium-range
362
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400 -
300 -
200 -
100-
CURRENT NSPS
360
180
BACT
(90% REMOVAL)
50
1975
1980
1985
1990
YEAR
FIGURE 8—Consumption of Powder River Basin coal
TABLE 4
1995 national FGD projections
Current NSPS
Revised NSPS
(90% Removal of S02)
FGD Sludge Produced*
(106 dry tonnes)
Cumulative Disposal Area
(km2, 1990-2000) f
FGD Water Consumed
(106m3)
FGD Energy Consumed
(% Total Coal Energy)
12
15
110
0.7%
55
92
607
3.8%
*Total coal ash production: 101 x 106 tonnes.
fNine-meter depth.
363
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LEVELS OF POLLUTION
EXCEED STANDARDS
air quality impacts of clustered power plants and the additive long-range impacts of
multiple clusters of plants. EPA is concerned that the operation of large new
coal-fired plants may lead to further degradation of air quality in existing
nonattainment areas or to consumption of the entire increment for SO2 specified in
regulations for the prevention of significant deterioration.
The clustering of power plants in the Lower Basin area near Louisville is
shown in figure 9. Also shown are air quality monitors indicating where levels of
S02 and particulates exceeded the ambient air quality standards in 1975. The four
power plants near Louisville are associated with the exceeded standards. Moreover,
the north-south line of these plants coincides with the direction of extremely
persistent winds (winds blowing at 10 to 15 miles per hour for periods of about 6
hours or more in a sector less than 22.5° wide). These wind conditions occur at
least several times each year. When the direction of persistent winds coincides with
the location of power plants, additive (frequently large) pollutant concentrations can
be transported downwind. High background levels of S02 or sulfates are frequently
associated with these meteorological conditions. EPA's Point-Multiple Point (PTMTP)
dispersion model has been used to estimate the additive ground-level S02
concentrations caused by the four power plants near Louisville (figure 10). Under
certain conditions these concentrations may cause violations of the 3-hour S02 air
quality standard, and if the violations are of sufficient duration, even the 24-hour
standard may be exceeded.
PROPOSED POWER PLANTS
AFFECTED
PREDOMINANT SO2 SOURCES
LONG-RANGE TRANSPORT
These results have implications for proposed power plants downwind along the
Ohio River. It is conceivable that the level of background emissions under
persistent-wind conditions may be so high that the siting of new sources will be
precluded by the regulations for the prevention of significant deterioration. Note the
locations of the three proposed power plants in figure 9. It is doubtful that these
locations can be justified without a reduction in emissions from existing sources.
Any judgment regarding the proposed plants should be backed up by ambient air
quality data from additional monitors and by further air quality analyses.
Table 5 indicates that, under current or revised NSPS, the predominant sources
of S02 emissions will be plants regulated by State Implementation Plans.
More particularly, in all years, the predominant S02 emission sources will be
post-1950 units subject to SIP emission limits. In the high growth case, up to 70
percent of SO2 emissions in 2000 could be due to SIP-regulated plants (plants on
line before 1977), and 23 percent will be due to plants on line after 1982 (plants
assumed to be subject to a revised NSPS). The predominance of SIP-regulated plants
as emission sources suggests that S02 emission levels might be substantially reduced
if existing SIP standards were made more stringent. In another study in which the
USM was used, in that case to investigate potential markets for physically cleaned
coal, one scenario included changing all S02 SIP limits to allow no more than 2.0
Ibs S02/106 Btu. If that hypothetical policy were to be implemented uniformly,
S02 emissions in 1985 would be reduced by 31 percent nationally. Regionally, there
would be reductions of 51 percent in the West North Central region, 45 percent in
the East South Central region, 30 percent in the South Atlantic region, 29 percent
in the East North Central region, and 26 percent in the Mid Atlantic region. These
emission reductions are illustrated by the lowest curve in figure 5 and by the
darkened areas in figure 11. Note that dramatic reductions in SO2 emissions are not
observed in the western U.S. The reason is that SIP limits in that part of the
country are already more stringent than the upper limit postulated in this scenario.
These integrated assessment results suggest that existing plants in specific subregional
areas of the country will need to be controlled in order to permit future growth.
Another primary application of the integrated assessment approach has been
the analysis of long-range pollutant transport. It is essential to consider long-range
transport when developing strategies for implementing the Clean Air Act amendment.
Pollutants can be carried for long distances over a region, affecting the attainment
of air quality standards in areas far removed from the emission source and hence
influencing the potential for long-term regional growth consistent with air quality
constraints.
364
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Miles
0 10 20 30 40 50
U—J I I I I
\IIIIII"
010 20 30 40 50 60 70
Kilometers
INDIANA
O
O
OHIO
Cincinnati
O MONITOR INDICATING NONATTAINMENT
(S02 OR TSP IN 1975)
POWER PLANT KEY
EXISTING PROPOSED
<, 500 MW • D
500 1000 MW • ^
> 1000 MW • L~H
FIGURE 3—Fossil steam plants and monitors indicating nonattainment
TABLE 5
Projected SC>2 emissions by coal plant regulatory category
Percentage of
Total Emissions
SIP Units
NSPS Units
BACT Units
1985
89%
9%
2%
2000
70%
7%
23%
Total Emissions (10^ Tons)
16.0
19.5
365
-------
2100
TOTAL OF PLANTS
3-HOUR AIR QUALITY STANDARD
PADDYS RUN PLANT(1
CANE RUN PLANTC3
24-HOUR AIR QUALITY STANDARD
GALLAGHER PLANTC2
ILL CREEK PLANT(^4
60
10
20 30 40
DOWNWIND DISTANCE (km)
50
FIGURE 10—Ground-level SC>2 concentrations from four power plants along a north-south
line near Louisville (from the EPA/PTMTP model)
CONTROLLING SO2 SOURCES
Teknekron has recently assisted EPA in evaluating the effects of the long-range
transport of pollutants into the State of Pennsylvania. In 1976 EPA Region III
notified Pennsylvania that every Air Quality Control Region in the state was a
nonattainment area for particulates and that Pennsylvania should therefore revise its
State Implementation Plan. In the Fall of 1977, Dr. Maurice Goddard, Secretary of
the Pennsylvania Department of Environmental Resources, asked EPA Administrator
Douglas Costle to investigate the degree to which S02 sources in upwind states were
contributing to Pennsylvania's ambient concentrations of particulate matter. Dr.
Goddard pointed out that preliminary results of Teknekron's integrated assessment
and of studies performed at Carnegie-Mellon University indicated that a significant
portion of Pennsylvania's nonattainment problem could not be addressed by revision
of the Pennsylvania SIP but rather had to be dealt with by controlling S02 sources
in the upwind states of Ohio and West Virginia. Dr. Goddard's petition was made in
accordance with Section 110 of the Clean Air Act, as amended, which requires that
SIP revisions in a given state not prevent or interfere with attainment or
maintenance of air quality in other states. At issue here were the implications for
Pennsylvania of Ohio's proposed SIP revision and of the proposed relaxation of S02
limits for two power plants in West Virginia.
Figure 12 conceptualizes the long-range-transport process, and figure 13 shows
the configuration of fossil steam plants in the three-state problem area. Under
certain meteorological conditions these power plants are upwind of Pennsylvania. In
cooperation with EPA Regions III, IV, and I and EPA's Office of Air and Waste
366
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-100% to -75%
-75% to -50%
-50% to -25%
-25% to 0%
+0% to 25%
+25% to 50%
0 for Either Case
I No Change
FIGURE 11-Percentage change in SO? emissions in year 2000 (BACT with more
stringent SIPS)
SECTOR OF
PERSISTENT WINDS
HOT SPOT
COUNTIES
.
BACKGROUNDKY
AIR QUALITY V.
CLASS 1 OR
NON ATTAINMENT
AREA
WEATHER
DATA '
LOCATION NONATTAINMENT
AREA
REGION OF MAXIMUM
IMPACT FROM
SECONDARY POLLUTANTS
FIGURE 12- Long-range transport (approximately 180 miles or 360 kilometers)
367
-------
VIRGINIA
< 1,000 MW
> 1,000 MW
MILES
25
I
25
50
i
75
100
. I
T I I I 1 I
25 0 25 50 TOO 150
KILOMETERS
FIGURE 13-7976 fossil steam power plants
368
-------
SOURCE RECEPTOR
RELATIONSHIP
WHEELING LEVELS EXCEED
PA. STANDARDS
Management, Teknekron has conducted meteorological and air quality analyses to
determine the contribution of these SO2 sources in Ohio and West Virginia to
particulate levels in western Pennsylvania.
Our study of 5 to 10 years of conventional weather data from National
Weather Service stations, as well as 1 to 2 years of special meteorological tower data
for a number of locations in the subregional problem area, has shown that the
extremely persistent winds in this area blow most frequently toward western
Pennsylvania from either Ohio or West Virginia. These conditions occur on the
average at least 30 times a year. Our analysis of the spatial correlation of extremely
persistent winds has revealed a source-receptor relationship in which pollutants from
the Huntington, West Virginia, area are transported over distances of 150 to 300
kilometers within a narrow sector downwind in the general direction of western
Pennsylvania.
Teknekron's analysis of measured sulfate levels in Wheeling, West Virginia,
from the Sulfate Regional Experiment (SURE) program shows that Wheeling's
average sulfate levels exceeded the Pennsylvania sulfate standard (10 /ag/m3) in every
month of the 1974-1975 period. Preliminary analysis of total suspended particulate
levels in Pennsylvania suggests that, for days when long-range-transport conditions
occurred, the sulfates coming from upwind sources provided the additional increment
needed to push Pennsylvania's particulate levels over the secondary standard.
ANALYTICAL TOOLS
Figure 14 illustrates one instance of long-range sulfate transport across state
borders. This sulfate episode occurred during several days in July 1974. Following
the passage of a high-pressure area, which led to stagnation of the air mass,
persistent winds developed. These winds transported the accumulated pollutants into
Pennsylvania. Further work is now being undertaken to determine more precisely the
impacts of long-range transport.
In evaluating the implications of environmental policies, one must always
undertake some form of integrated technology assessment, whether or not such an
approach is explicitly recognized. The analytical tools developed by Teknekron for
OEM I have utilized inputs from EPA's other research programs and have been
employed in the examination of a number of significant environmental issues. The
aim of these integrated analyses has been to provide EPA and other decision-making
bodies with a technically correct analytical framework and with self-consistent
quantitative results, enabling a consistent comparison of alternative strategies and
technical choices. The examples described in this paper are leading to further
refinement of EPA's analytical tools and to a better understanding of the likely
results of future decisions affecting our environment.
369
-------
JULY 9
WEST VIRGINIA
JULY 8
JULY 9
MILES
25
1
25
I
50 75 100
I I I
I I I I I I
25 0 25 50 100 150
KILOMETERS
FIGURE -\4-Sulfate episode on 7-9 July 1974
370
-------
TECHNOLOGY ASSESSMENT OF WESTERN
ENERGY RESOURCE DEVELOPMENT
INTRODUCTION
Irvin L. White, Ph.D.
Science and Public Policy Program
University of Oklahoma
The Western Energy Study or Technology Assessment of Western Energy
Resource Development was the first regional assessment sponsored by the Office of
Energy, Minerals and Industry as a part of the Integrated Assessment Program. The
3-year study is being conducted by the Science and Public Policy Program of the
University of Oklahoma with the assistance of two major subcontractors: the Radian
Corporation of Austin, Texas, and the Water Purification Associates of Cambridge,
Massachusetts; several other subcontractors; numerous consultants; and an advisory
committee whose members represent a variety of interests and perspectives, agencies,
and levels of government.
The overall purpose of this study is to determine the consequences of western
energy resource development and what can be done about them. Specific objectives
are to:
GEOGRAPHIC SCOPE
STUDY STRUCTURE
Determine and analyze impacts
Identify and define policy problems and issues
Identify and describe development alternatives
Evaluate and compare alternative policies and implementation strategies
Identify and describe research and data needs.
The study includes the eight Northern Great Plains and Rocky Mountain States
shown in figure 1: Arizona, New Mexico, Utah, Colorado, Wyoming, Montana, and
North and South Dakota. The development of six energy resources in this eight-state
area is assessed: coal, oil shale, uranium, oil, natural gas, and geothermal. The time
period covered by the study is 1975-2000.
The development alternatives considered are listed in table 1.
Six site-specific scenarios and one aggregate eight-state scenario are used to
structure the study. The scenarios for the six sites identified in figure 1 combine
representative local conditions (such as topography, meteorology, population, and
community services and facilities) and energy development technologies (from among
those listed in table 1). Analyses of the impacts likely to occur from the
development called for in these scenarios are intended to provide a basis for
generalizing about and identifying locational and technological factors which are
critical in determining development impacts that actually occur. Developers and
policymakers must control these factors to produce the desired energy product at
acceptable costs and risks. The aggregate eight-state scenario serves the same
analytical purpose for two levels of development within the study area. It also
provides a basis for studying impacts and policy problems and issues that are
nonlocal, such as a river basin, a subarea of the region, the region, and the nation.
371
-------
• RIFLE
KAIPAROWITS/
•ESCALANTE
CO
• NAVAJO/
FARMINGTON
FIGURE 1 — Western energy study area
PARTICIPATORY RESEARCH
SUBSTANCE OF STUDY
Another structural design feature emphasized is the involvement of stakeholders
or interested parties in the research. In fact, one of the distinctive features of the
Western Energy Study is this participatory research approach that was initiated at
the research design phase and has continued throughout the study. Contact and
communication was established and maintained with a broad range of public and
private officials and interest groups, as well as the advisory committee mentioned
above. This has incurred extensive field work, numerous meetings and presentations,
and a circulation of more than 500 copies of draft reports for external review.
The Western Energy Study is in the final month of its third year and a final
project report is being prepared. The study was designed to produce major reports
to provide the information and analytical base for the final report. These are listed
in table 2.
The above introduction and background information have, in general, described
what the Western Energy Study is, how it is being conducted, and the products it is
expected to produce. The broad scope of the study makes it impossible to give you
more than this brief overview. In order to be more specific and to give you a better
feel for the substance of the study, I want to focus attention on water availability
(1). As you probably know, water availability problems and issues are among the
most significant that will arise as a consequence of western energy development.
Very early in the Western Energy Study it was determined that water
availability could be a constraint on large scale energy development, especially on
regional coal and oil shale conversion. Water availability estimates vary widely. The
372
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WATER AVAILABILITY
ESTIMATES
COLORADO RIVER COMPACT
1922 Colorado River Compact divides water rights in the river between the Upper
and Lower Basin states (2). Under the provisions of this compact, Upper Basin
states guarantee Lower Basin states 75 million acre-feet over each consecutive
10-year period or an average of 7.5 million acre-feet/year. In 1944, the United
States agreed to guarantee Mexico 1.5 million acre-feet/year (3). Whether this water
for Mexico is to be provided by both the Upper and Lower Basin states or only by
the Lower Basin states is still being debated. If it is assumed that each basin
supplies half or 750,000 acre-feet/year, on the average, a total of 8.25 million
acre-feet would have to flow from the Upper Basin into the Lower Basin each year.
The availability of water in the Upper Basin for all uses would be the difference
between this 8.25 million acre-feet/year and the total flow in the Colorado River.
The 1922 Compact divided rights to water in the river based on an estimated
annual virgin flow of 16.2 million acre-feet/year (4). Other frequently cited virgin
flow estimates are 13.8 million acre-feet/year (5) and 13.5 million acre-feet/year (4).
(figure 2).
TABLE 1
Development alternatives
Coal:
Surface and Underground Mining
Direct Export by Unit Train and
Slurry Pipeline
Electric Power Generation
Gasification
Liquefaction
Transportation by Pipeline and
EHV
Oil Shale:
Underground Mining
Surface Retorting
Modified In-Situ
Transportation by Pipeline
Uranium:
Surface and Solutional Mining
Milling
Transportation by Train
Oil and Natural Gas:
Conventional Drilling and Pro-
duction
Enhanced Oil Recovery
Transportation by Pipeline
Geothermal:
Hot Water and Hot Rock
Electric Power Generation
Transportation by EHV
VIRGIN FLOW ESTIMATES
Virgin flow estimates include all of the water which flows in the river. But
flows can also be estimated and measured at a particular point on the river in which
case the estimate or measurement does not include water consumed upstream of the
point on the river where the estimate or measurement is made. The most significant
measuring point of the Colorado River is Lees Ferry, Arizona, the official dividing
point between the Upper and Lower Basins specified in the Colorado River
Compact.
373
-------
LEES FERRY FLOW DATA
The Department of the Interior has published flow data for a point very close
to Lees Ferry for the period 1941-1974. The average annual flow over this 34-year
period was 10.4 million acre-feet (6). For the decade 1960-1969, the average annual
flow was 8.0 million acre-feet (6) and in 1974, measured flow at Lees Ferry was
8.9 million acre-feet. (6). (figure 2.)
TABLE 2
Western energy study reports
Two work plans or research designs:
First Year Work Plan for a Technology Assessment of Western
Energy Resource Development (1976)
Work Plan for Completing a Technology Assessment of Western
Energy Resource Development (1978)
A description of development technologies:
Energy From the West: Energy Resource Development Systems
(forthcoming)
Two impact analysis reports:
Energy From the West: A Progress Report of a Technology
Assessment of Western Energy Resource Development (1977)
Energy From the West: Impact Analysis Report (forthcoming)
A policy analysis report:
Energy From the West: Policy Analysis Report (forthcoming)
Subcontractor or consultant reports on:
Water requirements (Water Purification Associates)
Holding ponds (Radian)
Ponded effluents (Radian)
Planning and growth management (Western Governors' Policy Office)
Development on the Navajo Reservation (University of Oklahoma)
Transportation (University of Illinois)
Air quality (Teknekron)
UPPER BASIN WATER
AVAILABILITY
ANTICIPATED WATER
DEMANDS
The best available estimates of the quantity of water currently being consumed
above Lees Ferry range from 3.2 million acre-feet/year (7) to 3.7 million
acre-feet/year (8). Lacking a better data base, these consumption numbers, the three
estimates of virgin flow, and the flows actually measured at Lees Ferry can be used
to estimate the availability of water in the Upper Colorado. As indicated in figure 2,
these range from a deficit of 250,000 acre-feet/year, if the average acre-feet/year
measured flow for the period 1960-1969 is used, to a surplus of 4.25 million
acre-feet/year, if the 1922 compact virgin flow estimate is used. This is the range of
estimates of water available in addition to 8.25 million acre-feet/year flowing into
the Lower Basin and the estimated 3.7 million acre-feet/year currently being
consumed in the Upper Basin.
The Department of the Interior's estimate of increased water use by nonenergy
users is 1.5-1.6 million acre-feet/year by the year 2000 (8). The Western Energy
Study's estimates of water demand for energy development by the year 2000 range
from 600,000 acre-feet/year for a low energy demand case with prudent water
management to 1.1 million acre-feet/year for a high energy demand case and
business as usual water management (9). As shown in figure 3, this analysis leads to
the conclusion that it is very probable that by the year 2000 there will not be
enough water to meet all of the anticipated demands for water in the Upper
Colorado River Basin. This finding indicates that policymakers will have major water
availability problems and issues to deal with if large-scale western energy
374
-------
FIX-OPTION
IDENTIFICATION
development occurs. Within the eight-state study area, the most difficult political
decision will be to decide who among the competitors is to receive water? Will
Upper or Lower Basin water supplies be cut or will water be made available to
energy users by limiting the quantity of water made available to other uses such as
agriculture?
Public officials often have some discretion with regard to which problems and
issues they choose to deal with and how they deal with them. Almost without
exception, finding technological fixes for dealing with problems is more politically
attractive than requiring significant changes in behavior. Knowing that this is the
case, when it became clear that water availability could be a significant constraint
on western energy development, Water Purification Associates was commissioned to
conduct a study of configuration and process design changes which could reduce the
water consumption of energy conversion technologies. A preliminary analysis was
also conducted to identify water conservation opportunities in agriculture.* Both of
these analyses were undertaken to identify technological fix options for policymakers
faced with making difficult policy choices when there will not be enough water in
the Upper Colorado River to meet the anticipated demand if current practices and
energy and nonenergy development continue.
Million Acre-Feet/Year
Source
of
Estimate
10
i
15
•Required Flow to Lower Basin
1922 COMPACT
TIPTON & KALMBACH
LAKE POWELL
DOI 1941-1974
DO I 1960-1969
DOI 1974
"DOI MEASUREMENTS AT LEES FERRY, ARIZONA
FIGURE 2-Estimates of average flow in Colorado River*!
*Water Purification Associates will pursue this analysis of conservation alternatives in
agriculture during the fall of 1978.
375
-------
Million Acre-Feet/Year
5 10
15
Source
of
Estimate
1922 COMPACT
TIPTON & KALMBACH
I
LAKE POWELL
DOI 1941-1974
DOI 19601969
DOI 1974
tDOl MEASUREMENTS AT LEES FERRY, ARIZONA
FIGURE 3-Projections of average flow in Colorado River, year 2000*
General
Alternative
Specific
Alternative
AUGMENTATION
CONSERVATION
DECREASE OR ELIMINATE
SOME USES
Diversions and Transfers
Impoundments
Weather Modification
Uplands Vegetation Management
Energy Facility Cooling and Process Design
Municipal Wastewater for Facility Cooling
Irrigation Efficiency Improvement
Crop Selection
Land Management
Municipal
Water Intensive Agriculture
Water Intensive Energy Resource Development
Water Transfers From Energy Consumers
FIGURE ^-Policy alternatives for water availability issues
376
-------
WATER AVAILABILITY
ALTERNATIVES
Figure 4 shows several water availability alternatives now being evaluated in
the Western Energy Study, including water conservation in both energy and
agriculture. Augmentation and conservation are two kinds of alternative approaches
for meeting the overall water needs of Upper Basin users. Augmentation would
achieve this objective either by adding to the overall water supply or using
impoundments to make water available where it is needed. On the other hand,
conservation or increased efficiency would get more use out of the existing water
supply. For example, more efficient irrigation technologies or wet/dry or dry rather
than wet cooling might be used to reduce the quantity of water required for
continued agricultural and energy development.
Each alternative is being evaluated in the Western Energy Study on the basis
of five criteria: effectiveness, efficiency, equity, flexibility, and acceptability. Figure
5 shows how these criteria are applied to water availability alternatives.
POTENTIAL SAVINGS
TRADE-OFFS FOR
ALTERNATIVES
SUMMARY
Figure 6 shows two estimates of the water required by the energy conversion
technologies being considered in the Western Energy Study. Table 3 summarizes the
water conservation opportunities when wet/dry or dry cooling rather than wet
cooling is used. As the table shows, there are potential water savings with these
alternatives. However, the dollar cost to realize these water savings may also be
large. The most economical cooling alternative for all coal conversion technology is
wet cooling when water costs less than 20 cents per 1,000 gallons. For synthetic
fuel technologies, some dry cooling becomes economic at a water cost of about
$1.50 per 1,000 gallons** and, for power plants, at about $3.65 to $5.89 per 1,000
gallons depending on the site. The added dollar per Btu cost to save water is
generally low for synthetic fuels. For example, in the case of Synthane when water
costs 20 cents per 1,000 gallons, from 1,900-2,300 acre-feet/year can be saved at a
cost ranging from 0.9—1.5 cents per million Btu's. At a product gas price of $3.00
per million Btu's, the cost of water savings would increase the price of the gas by
about 0.3 to 0.5 percent.
The price increase would be greater for electric power. If electricity is priced
at 2.5 cents per kilowatt hour, a 0.1-0.2 cost per kilowatt hour price increase to
save water would represent an increase of about 4 to 8 percent in the price of
electricity.
I have explicitly discussed only the effectiveness and efficiency of wet/dry
rather than wet cooling. The analysis goes on to evaluate also on the basis of the
other criteria mentioned earlier. Rather than draw a conclusion that one alternative
is either preferable or better than another, we attempt to show what the trade-offs
would be for each alternative. Implementation alternatives are also evaluated and
compared.
An overview has been given of the Western Energy Study, the objectives it is
intended to achieve, how it has been structured and conducted, and the kinds of
results it is producing. Water availability was chosen to demonstrate how we went
about identifying and defining the problems and issues policymakers are likely to
have to deal with, how this led to additional analysis to identify alternative courses
of action, and how these alternatives were analyzed to inform policymakers
concerning the consequences of their policy choices. Specifically, I illustrated the
water and dollar cost of energy tradeoffs associated with the choice of cooling
options. Knowing these trade-offs, both public and private sector policymakers can
make better informed choices. Certainly they will still have to make choices under
conditions of uncertainty; but the level of uncertainty can be considerably reduced
by studies such as the Western Energy Study.
*These costs vary by site but are approximately correct for all sites.
377
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CRITERIA
APPLIED TO WATER AVAILABILITY
SAMPLE MEASURES
EFFECTIVENESS
How much water can be saved
or added?
Is it a long-term or short-
term solution?
Percentage increase in supply
Acre-feet per year
Duration (years) of solution
EFFICIENCY
What are economic costs, risks, and
benefits of saving water?
K
Dollar costs
Perception of risks
Increase/decrease in concen-
tration of pollutants
Perceptions of scenic and
aesthetic degradation
EQUITY
FLEXIBILITY
What is distribution of costs,
risks, and benefits?
Is the alternative reversible?
Is it implementable?
Which states, regions are bene-
fited or deprived
Discrepancies in parties-at-
interest ability to pay
Will the alternative account
for locational differences?
Uniform or flexible
Reversible or irreversible
Dollar costs of administration
Degree of innovation
ACCEPTABILITY
How strongly will parties-at-
interest respond?
Declared opposition
Any decision-making processes open?
Open, partial, or closed
participation
FIGURE 5-Criteria for evaluation
378
-------
175
150
G
D
"o 125
a.
- 100
WATER REQUIREMENTS (MIN./MAX.)
CD
CO
O
o
75
50
25
Technology: >- 2
§.&
I 0
o
o> •=
«
O
1.1
O TO
O £
QJ
>~
1 §•
co £
FACILITY
LOAD FACTOR
SIZE
Power Generation 70%
Lurgi Gasification 90%
Synthane Gasification 90%
Synthoil Liquefaction 90%
TOSCO II Oil Shale Retort 90%
Slurry Pipeline 100%
3,000 MWe
250 MMscfd
250 MMscfd
100,000 bbl/day
100,000 bbl/day
25 MMmtpy
FIGURE 6—Water requirements for energy conversion technologies
TABLE 3
Water conserved on an equivalent basis (gallons/million Btu)
Technology
Power Generation
Btu (e)
Btu (th)
Lurgi Gasification
Synthane Gasification
Synthoil Liquefaction
TOSCO II Oil Shale
Retort
Water
Consumed
for Wet
Cooling
116-144
39-49
14-24
32-36
15-19
23
Maximum Conservation
Wet/Dry
PERCENT
61-68
61-68
41-72
48-52
65
18
Cooling
GALLONS
78.9-88.5
26.4-30.1
9.8-10.1
16.7-17.4
9.7-12.4
4.2
Maximum
Dry
PERCENT
80-91
80-91
54-96
65-69
68-86
23
Conservation
Cooling
GALLONS
105.1-115.
35.3-39.3
12.9-13.4
22.2-23.3
12.9-13
5.4
5
379
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References
1. Plotkin, Steven E., Harris Gold, and Irvin L. White. "Water and Energy in
the Western Coal Lands." Water Resources Bulletin (forthcoming); White,
Irvin L., et al. Energy From the West: A Progress Report of a Technology
Assessment of Western Energy Resource Development, 4 vols. Washington,
D.C.: U.S., Environmental Protection Agency, 1977; White, Irvin L., et al.
Energy From the West: Impact Analysis Report, Washington, D.C.: U.S.,
Environmental Protection Agency, forthcoming, 1978.
2. Colorado River Compact of 1922, 42 Stat. 171, 45 Stat. 1064, declared
effective by Presidential Proclamation, 46 Stat. 3000 (1928).
3. Treaty Between the United States of America and Mexico Respecting
Utilization of Waters of the Colorado and Tiajuana Rivers and of the Rio
Grande, February 3, 1944, 50 Stat. 1219 (1945), Treaty Series No. 994.
4. Stockton, Charles W. and Gordon C. Jacoby. Long-Term Surface Water
Supply and Streamflow Trends in the Upper Colorado River Basin. Lake
Powell Research Bulletin N. 18. Los Angeles, Calif.: University of California
at Los Angeles, Department of Geophysics and Planetary Physics, 1976.
5. Tipton and Kalmbach, Inc. "Water Supplies of the Colorado River" in U.S.
Congress, House of Representatives, Committee on Interior and Insular
Affairs. Lower Colorado River Basin Project Hearings Before the
Subcommittee on Irrigation and Reclamation. 89th Congress, 1st Session,
1965.
6. U.S., Department of the Interior. Quantity of Water: Colorado River Basin.
Progress Report No. 8. Washington, D.C.: Department of the Interior, 1977.
7. U.S., Department of the Interior, Bureau of Reclamation. Westwide Study
Report on Water Problems Facing Eleven Western States. Washington, D.C.:
Government Printing Office 1975.
8. U.S., Department of the Interior, Water for Energy Management Team.
Report on Water for Energy in the Upper Colorado River Basin. Denver,
Colo.: Water for Energy Management Team, 1974.
9. White, Irvin L., et al. Energy From the West: A Progress Report of a
Technology Assessment of Western Energy Resource Development, 4 vols.
Washington, D.C.: U.S., Environmental Protection Agency, 1977; and White,
Irvin L., et al. Energy From the West: Impact Analysis Report. Washington,
D.C.: U.S. Environmental Protection Agency, forthcoming in 1978.
380
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questions
oc answers
Walter B. Smalley
Peanuts International Limited
C. Thomas Bruer
Georgia Power Company
all/lill! la«\\\\\\
COMMENT
When Frank Press made his keynote address he
spoke, hopefully, of building a consensus as to which
path we should take toward assuring a future with
adequate energy. Yesterday, in their excellent presenta-
tions on sulfates and acid rain, Drs. Hussar and
Dochinger approached that consensus and also put it on
a world level by comparisons with Europe.
EPA's recent releases mentioned that June 5 is
World Environment Day. The fact sheet with the release
quotes world-famed ocean man, Jacques Yves Cousteau,
as saying, "Each month we now pour so many millions
of tons of poisonous wastes into the living seas and in
perhaps 20 years, perhaps sooner, the oceans will have
received their mortal wound and will start to die. I do
not say this lightly." As a member of the American
Oceanic Organization and the Cousteau Society, I wish
to share with you a short but important quote from the
Cousteau Society's Calypso Log of March, 1978, that
relates directly to what has been said here the last 2
days. It has made clear that the increase in human
population since the time of Aristotle has increased
human wastes by the same order, that it is the amount
of human waste that has become a problem.
"Pollutants are not inherently bad. They are
almost always valuable commodities in the wrong places.
The basic cause of human pollution is an inefficient
technology and a failure of humans to develop closed-
loop systems. It is easier, but never more economical, to
discard wastes than to recycle them. Then we modern
humans worry that we are running out of resources.
The chemicals are not gone; they are misplaced. They
are scattered throughout the environment in a way that
we cannot reuse them."
For nearly 5 months, the crew of the Calypso
worked to determine the concentrations of these toxic
materials in the marine plants and animals of the
Mediterranean. It might take another 6 months or more
for laboratories to analyze the thousands of samples we
have sent them. While we are waiting for the results, we
might well ponder Aristotle's question, what are we as a
381
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species doing to ourselves? We do not have to answer
Aristotle, but we do have to answer to ourselves
because pollution, a modern concept, is not a figment
of anyone's imagination. Now, this is leading up to
asking, have we reached a reasonable consensus and
where do we go from here?
QUESTION
In modeling work, has there been any explicit
attempt to incorporate the uncertainty that the pur-
chasing utility incurs in choosing a technology or are
only best-guess costs used? Is there an attempt to in-
corporate a possible spread of costs?
RESPONSE: Dr. Peter M. Cukor (Teknekron, Inc.)
We recognize that there is uncertainty, not only in
the costing technology but in the ability to obtain a
construction and operating permit. We have handled
this, in part, through what we call scenarios; that is,
running cases where there are relatively high uses of
nuclear or coal-fired units, higher uses of oil-fired units,
and higher yet of gas-fired units from a base case. As
our base case projection, we use the announced plans of
the individual utility firms as submitted to the Federal
Power Commission with their 20-year forecast each
April 1. From those we do deviations as our technology
mix. The results I presented, however, involve the base
case.
382
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PARTICIPANTS' INDEX
Abbott, James H. . . . Page 323
EPA/I ERL
Research Triangle Park, NC 27711
919/541-2925
Albert, Ph.D., Roy E. . Page 63
EPA/Carcinogenic Assessment
Group
401 M St., SW
Washington, DC 20460
202/755-3968
Altshuller, Ph.D., A. Paul . . Page 153
EPA/ESRL
Research Triangle Park, NC 27711
919/541-2191
Auerbach, Ph.D., Stanley . . Page 153
Oak Ridge National Laboratory
Environmental Science Division
P.O. Box X
Oak Ridge, TN 37830
615/483-8611 x31935
Belding, Ph.D., John A Page 339
DOE/Energy Technology
Room 2220 - MS 2221 C
20 Massachusetts Avenue, NW
Washington, DC 20545
202/376-4602
Bowen, Jr., D.Eng., Joshua S. . Page 291
EPA/IERL
Research Triangle Park, NC 27711
919/541-2470
Bridbord, M.D., Kenneth . . Page 63
HEW/NIOSH
5600 Fishers Lane
Rockville, MD 20857
301/443-6437
Burr, Jr., M.D., William W Page 63
DOE/Division of Biomedical
and Environmental Research
Washington, DC 20545
301/353-3153
Cukor, Ph.D., Peter M. Page 353
Teknekron, Inc.
2118 Milvia Street
Berkeley, CA 94704
415/548-4100
Curtis, Willie R. . • pa9e 187
USDA/Forest Service
204 Center Street
Berea, KY 40403
606/986-8431
Dochinger, Ph.D., Leon S. . .
USDA/Forest Service
P.O. Box 365
Delaware, OH 43015
614/369-4471
Drehmel, Ph.D., Dennis C. .
EPA/IERL
Research Triangle Park, NC 27711
919/541-2925
Elder, H. William
TVA/Emission Control
Development Projects
Muscle Shoals, AL 35660
205/383-4631 x516
Page 113
Page 323
Page 339
Page 29
Page 313
Epler, Ph.D., James L
Oak Ridge National Laboratory
Biology Division
P.O. Box Y
Oak Ridge, TN 37830
615/483-8611 x37659
Freedman, Ph.D., Steven I.
DOE/Energy Technology Branch
400 1st Street
Railway Labor Bldg., Room 408
Washington, DC 20545
202/376-9345
Gage, Ph.D., Stephen J Page 7
EPA/ORD
401 M Street, SW
Washington, DC 20460
202/755-2600
Gardner, Ph.D., Donald E.
EPA/HERL
Research Triangle Park, NC 27711
919/541-2531
Glass, Ph.D., Gary E.
EPA/ERL
6201 Congdon Blvd.
Duluth, MIM 55804
218/783-9573
Page 51
Page 121
Glass, Ph.D., Norman R.
EPA/ERL
200 SW 35th Street
Corvallis, OR 97330
503/757-4671
Page 113
Harris, Eugene F. . . .
EPA/IERL
5555 Ridge Avenue
Cincinnati, OH 45268
513/684-4417
Page 165
383
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Hazucha, M.D., Milan
EPA/HERL
Research Triangle Park, NC 27711
919/541-2601
Hill, Ronald D.
EPA/I ERL
5555 Ridge Avenue
Cincinnati, OH 45268
513/684-4410
Page 51
Page 165
Page 153
Page 165
Hirsch, Ph.D., Allan .
DOI/Fish and Wildlife Service
Washington, DC 20240
202/634-4900
Hubbard, S. Jackson
EPA/I ERL
5555 Ridge Avenue
Cincinnati, OH 45268
513/684-4417
Hucko, Richard E Page 221
DOE/Coal Preparation & Analysis Lab.
4800 Forbes Avenue
Pittsburgh, PA 15213
412/892-2400
Husar, Ph.D., Rudolf B. . . Page 75
Washington University
Dept. of Mechanical Engineering
P.O. Box 1185
St. Louis, MO 63130
314/889-6099
Jones, III, Ph.D., Herbert C. . Page 153
TVA/Division of Environmental
Planning
Muscle Shoals, AL 35660
919/541-2915
Jones, Julian W Page 275
EPA/IERL
Research Triangle Park, NC 27711
919/541-2489
Kaplan, Norman .... Page 253
EPA/IERL
Research Triangle Park, NC 27711
919/541-2556
Kilgroe, James D. . Page 221
EPA/IERL
Research Triangle Park, NC 27711
919/541-2851
Knelson, M.D., John H. Page 51
EPA/HERL
Research Triangle Park, NC 27711
919/541-2601
Large, David B Page 353
Teknekron, Inc.
2118 Milvia Street
Berkeley, CA 94704
415/548-4100
Likens, Ph.D., Gene E Page 113
Cornell University
221 Langmuir Laboratory
Ithaca, NY 14853
607/256-4631
MacCracken, Ph.D., Michael C. . . Page 75
DOE
University of California
Lawrence Livermore Laboratory
P.O. Box 808
Livermore, CA 94550
415/422-1826
Martin, George Blair Page 291
EPA/IERL
MD 65
Research Triangle Park, NC 27711
919/541-2235
Maxell, Michael A Page 253
EPA/IERL
MD 61
Research Triangle Park, NC 27711
919/541-2578
MclMelis, Ph.D., David N Page 95
EPA/EMSL
Las Vegas, NV 89114
702/736-2969 x261
Miller, Ph.D., Frederick Page 51
EPA/HERL
Research Triangle Park, NC 27711
919/541-2601
Nelson, Ph.D., Norton . . .
NY University Medical Center
Institute of Environmental
Medicine
550 1st Avenue
New York, NY 10016
212/679-3200 x2881
Neuhold, Ph.D., John M. .
Utah State University
Utah State Ecology Center
Logan, UT 84321
801/752-4100 x7411
Page 63
Page 153
Niemann, Brand L.
Teknekron, Inc.
2118 Milvia Street
Berkeley, CA 94704
415/548-4100
Page 353
384
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Perhac, Ph.D., Ralph M. . . .
Electric Power Research Institute
P.O. Box 10412
Palo Alto, CA 94303
415/855-2000
Press, Ph.D., Frank
Office of Science
and Technology Policy
Executive Office Bldg.
Washington, DC 20500
202/456-7116
Princiotta, Frank T.
EPA/ORD/OEMI
401 M Street, SW
Washington, DC 20460
202/755-2737
Page 75
. Page 9
Page 339
Pueschel, Ph.D., Rudolf F.
DOC/NOAA
Boulder, CO 80302
303/499-1000 x6360
Rail, M.D., Ph.D., David P. .
HEW/NIEHS
P.O. Box 12233
Research Triangle Park, NC 27709
919/541-3201
Reznek, Ph.D., Steven R.
EPA/ORD/OEMI
401 M Street, SW
Washington, DC 20460
202/755-4857
Singer, Marvin I.
DOE/Environmental and Socio-
Economic Impact,
Resource Applications
Room 4117
20 Massachusetts Ave., NW
Washington, DC 20545
202/376-9086
Smith, Lowell F.
EPA/ORD/OEMI
401 M Street, SW
Washington, D.C. 20460
202/426-2683
Page 95
Page 63
Page 5
Page 339
Page 353
Waters, Ph.D., Michael D. . Page 29
EPA/HERL
Research Triangle Park, NC 27711
919/541-2537
White, Ph.D., Irvin L Page 371
University of Oklahoma
Science and Public Policy Program
601 Elm Avenue, Room 432
Norman, OK 73019
405/325-2555
Wilson, Jr., Ph.D., William E. . . Page 75
EPA/ESRL
Research Triangle Park, NC 27711
919/541-2551
Yeager, Kurt E . Page 339
Electric Power Research Institute
3412 Hillview Avenue
P.O. Box 10412
Palo Alto, CA 94303
415/855-2456
Van Horn, Andrew J. . Page 353
Teknekron, Inc.
2118 Milvia Street
Berkeley, CA 94704
415/548-4100
Warren, Charles . . . . . Page 19
President's Council
on Environmental Quality
722 Jackson Place
Washington, DC 20006
202/633-7027
385
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FEDERAL AGENCY ACRONYMS
DOE Department of Energy
EPA Environmental Protection Agency
EMSL Environmental Monitoring and Support Laboratory
ERL Environmental Research Laboratory
ESRL Environmental Science Research Laboratory
HERL Health Effects Research Laboratory
I ERL Industrial Environmental Research Laboratory
OEMI Office of Energy, Minerals and Industry
HEW Department of Health, Education and Welfare
NIEHS National Institute of Environmental Health Sciences
NIOSH National Institute of Occupational Safety and Health
HUD Department of Housing and Urban Development
NASA National Aeronautics and Space Administration
TVA Tennessee Valley Authority
USDA U.S. Department of Agriculture
ESCS Economics, Statistics and Cooperative Service
FS Forest Service
SCS Soil Conservation Service
SEA/CR Science and Education Administration, Cooperative Research
SEA/FR Science and Education Administration, Federal Research
USDC U.S. Department of Commerce
NBS National Bureau of Standards
NOAA National Oceanic and Atmospheric Administration
OEA Office of Environmental Affairs
USDI U.S. Department of Interior
BOM Bureau of Mines
FWS Fish and Wildlife Service
USGS U.S. Geological Survey
386
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TECHNICAL REPORT DATA
{Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/9-78-022
3. RECIPIENT'S ACCESSION-NO.
riTLE ANDSUBTITLE ENERGY/ENVIRONMENT III
Proceedings of the Third National Conference on the
Interagency Energy/Environment R&D Program, Washington
D.C., June 1 & 2, 1978
5. REPORT DATE Date of Publicatior
October 1978
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Decision Series Editor:
Technical Editor:
Richard M. Laska, EPA/ORD
Elinor Voris
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
Automation Industries, Inc.
Vitro Laboratories Division
14000 Georgia Avenue
Silver Spring, MD 20910
626
11. CONTRACT/GRANT NO.
EPA 68-01-2934
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Research & Development
Office of Energy, Minerals & Industry
Washington, B.C. 20460
13. TYPE OF REPORT AND PERIOD COVERED
Decision Series-thru June '78
14. SPONSORING AGENCY CODE
EPA-ORD-OEMI
15. SUPPLEMENTARY NOTES
This project is part of the EPA-planned and coordinated Federal Interagency
Energy/Environment R&D Program.
16. ABSTRACT
This publication is the complete Proceedings of the Third National Conference
on the Interagency Energy/Environment R&D Program.
Energy/Environment III provides an update of Interagency research programs in
particular areas, including health effects, transport processes and ecological
effects, mining methods and reclamation, control technology and integrated technolog]
assessment. Complete texts of all papers are presented, along with addresses, panel
discussions, and question and answer periods. The volume is illustrated with
tables and figures.
Composed of more than a dozen Federal agencies, the Interagency Energy/
Environment R&D Program is designed to assure that unresolved environmental issues
are not a barrier to timely and safe development of our domestic energy resources.
The Office of Energy, Minerals and Industry within EPA's Office of Research and
Development has, as coordinator, invested approximately $100 million a year in the
Program since its inception in fiscal year 1975.
(Circle One or More)
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c. cos AT I Field/Group
Energy Conversion
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(6F) 8A 8F
8H 10A (10B)
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7A
8. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Report)
21. NO. OF PAGES
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Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
AU.S. GOVERNMENT PRINTING OFFICE: I978 O—620-007/3725 REGION 3-1
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