environmental
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solid
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Sewage Sludge
Back To Th6 Land?
Bloomington, Indiana, 1976. When farmer Ron Nehrig discover-
ed the sewage sludge he'd used as a soil conditioner was heavily
contaminated with cancer-causing PCBs, he became concerned
about his family's health. Upon his insistence city officials
tested the milk from a family cow that had grazed on the
sludge-treated pasture. They found the milk fat contained twice
the amount of PCBs allowed by the Federal government.
Farmer Nehrig's pliaht is part of a sludge crisis that threatens
to engulf many communities, bringing with it a possible environ-
msntal nightmare. As municipal wastewater treatment plants
spuw out over 25 billion gallons of sludge daily, cities are hard
pressed to find disposal methods that are both economically
acceptable and environmentally sound.
Ironically, the onslaught of sludge is a direct result of the
battle against water pollution: the cleaner we get our waters, the
more .sludge we produce. The disposal dilemma is becoming in-
creasingly acute as communities upgrade their sewage treatment
processes (as required by the 1972 Federal Water Pollution Con-
trol Act). The Environmental Protection Agency (EPA) esti-
mates that by 1985 we -yill have to contend with at least twice
as much sludge as we face today.
Every time anyone flushes the toilet, does their laundry, or
uses the garbage disposal they create sludge. Largely due to the
contribution of local industries that use the public sewage
system, municipal sludge often contains detectable amounts of
heavy metals and toxic chemicals that may endanger human
health and pollute the environment.
Currently about 15 percent of the nation's sludge is dumped
into the ocean, 35 percent is burned (incinerated), 25 percent
is buried (landfilled), and 25 percent is spread on the land as a
soil conditioner (landspread). However, this pattern is rapidly
changing as the result of environmental legislation and the rising
costs of' traditional disposal methods. Because of mounting
evidence of serious damage to the marine ecosystem,' EPA has
ruled that all ocean dumping of sludge must cease by 1981.
Simultaneously, incineration is being priced out of range for
most communities; only the largest cities can pay for expensive
fuel and adequate air pollution control equipment.
With more and more sludge and fewer places to put it, cities
are looking to the land as the answer to their sludge disposal
woes. Because urban landfill space is rapidly disappearing, com-
munities are trying to keep as much out of the landfill as
possible. This means that wherever it.is practical, cities are likely
to find landspreading the most attractive disposal alternative.
At first glance, landspreading urban sludge appears to be the
ideal solution to a compiicated problem: an otherwise wasted
resource, loaded with soil-enriching organics, can be used to
build the soil and close the ecological circle. This sounds like the
perfect environmental answer, and both city officials and much
of the environmental community tout it as such.
But there's a catch. If sludge contaminants have caused
enough concern to ban sludge from the ocean, there is good
reason to fear the same contaminants will wreak havoc on the
land, particularly if they enter the food chain. Scientists,
environmentalists, and offices within EPA sharply disagree as to
just how much of a hazard is posed by applying sludge to farm
land. These experts heatedly debate what levels of heavy metals,
toxic chemicals, and pathogens (disease-causing organisms) are
"safe;" some believe that even sludges low in heavy metals are
dangerous on food chain crops, while others claim that
vegetables can be safely grown on highly contaminated sludges.
The unfortunate result of this numbers squabble is that the
public may be misled about the seriousness of the problem.
Close examination of the evidence indicates that there is
cause for grave concern.
He
Leavy metals, including cadmium, chromium, lead, mercury,
nickel, and zinc, can accumulate in food chain plants and
animals in sufficient concentrations to endanger human health.
The U.S. Food and Druq Administration (FDA) has singled out
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cadmium as the greatest threat to human health through the
food supply.
Cadmium is a persistent, pervasive metal that has entered our
environment primarily as a result of the mining and refining of
zinc ores. It is mainly used by the electroplating industry, the
pigments and compounds industries, and the metallurgy
industry, and it ends up in products ranging from motor oil to
television tubes.
Even present levels of cadmium in our air, drinking water,
cigarette tobacco and food cause some scientists concern. Cad-
mium is a cumulative poison that is retained mostly in the liver
and kidneys. In high concentrations it is known to cause acute
kidney disease, and it has been linked with cancer in tin smelter
workers; in much lower concentrations it has been associated
with hypertension and heart disease. Scientists worry most
about the lower exposure chronic diseases, for we already
absorb more cadmium than prescribed by international
standards. Both the Food and Agricultural Organization and the
WHAT IS IN SLUDGE?
Sludge, a watery substance typically composed of 90 to
95 percent water and 5 to 10 percent solids, is the end
product of the wastewater cleanup process. When sewage
from homes and industries enters a wastewater treatment
plant it undergoes primary treatment to strain out large
solids and grit. In 70 percent of our communities it then
undergoes further processing — secondary treatment — which
removes up to 90 percent of the organic material present in
the effluent. If there is no other processing, raw sludge
results; it is very smelly in this form, and contains large
numbers'of disease-causing organisms (pathogens).
In most cases, the sludge is further treated and is con-
verted into a less toxic, less chemically active form. This pro-
cess, known as stabilization, eliminates most of the odor
and pathogen problems. The basic ways of stabilizing sludge
are digestion, composting, and chemical treatment; digestion
is most common.
• Digestion is a biological process in which micro-
organisms interact with the sludge either in the presence
of air (aerobically) or in the absence of air (anaerobically).
Digested sludge may be left in liquid form or may be
dewatered.
• Composting is familiar to many. In this process wood
chips, bark, organic refuse or some other bulking agent is
a.ded to dewatered sludge. Over time the sludge decom-
poses, producing temperatures as high as 140° F. The end
product is an earthy, humus-like product that is almost
odorless and pathogen-free.
• Chemical treatment involves adding large amounts
of lime.
About three-quarters of sludge soiids are bio-degradable,
organic materials that give sludge its soil-enriching reputa-
tion. The remaining portion is composed largely of silica
(sand), potassium, iron, and can contain trace amounts of
heavy metals such as cadmium, lead, and mercury, and per-
sistent toxic chemicals such DDT, aldrin, dieldrin, and poly-
chlorinated biphenyls '(PCBs). It is this small portion of
sewage sludge that is cause for serious concern.
World Health Organization of the United Nations recommend a
maximum cadmium intake of 57 to 71 micrograms per day
from all sources; a recent FDA study concludes that the average
American consumes 72 micrograms of cadmium daily from food
and drink alone.
Landspreading sludge on food crops causes such concern
because sludges consistently have cadmium concentrations high
above the average soil level of .15 parts per million (ppm); the
sludge in over half of our communities has more than 16 ppm
cadmium, and urban sludges have been found with more than
3600 ppm cadmium. Since food is our major source of cadmium
intake, the large scale application of urban sludges to cadmium-
absorbing leafy green vegetables and grains could significantly
increase our intake. Salad lovers and cereal eaters beware!
Dr. Charles Jelineck, FDA's Deputy Associate Director for
Technology, warns that "new developments should not be
established on a large scale that could cause a significant and
possibly irreversible increase of cadmium in the food supply.
The uncontrolled, widespread application of sewage sludge on
land should be considered in this category."
' loxic organic compounds in sludge may also threaten human
health and the environment. These very persistent chemicals
include pesticides such as DDT, aldrin, dieldrin, and chlordane,
as well as the polychlorinated biphenyls (PCBs) that ended up
in farmer Nehrig's milk. What little we know about the fate of
these substances in the ecosystem and tolerance levels in hu-
mans is not reassuring.
Toxic chemicals are potent, cancer-causing agents that
already have embedded themselves in food chain plants and
animals; any increased exposure should be avoided.
Numerous pathogens, .or disease-causing organisms, are
always present in municipal sludge. These include bacteria and
viruses, such as salmonella and tuberculosis, and parasites.
According to FDA's Dr. Jelineck, the main concern is that
grazing animals or people may come into contact with these
infectious agents.
UNDER CONTROL?
There are ways to minimize sludge's adverse impacts through
careful site management and crop selection. Perhaps the most
important of these measures is to maintain the soil in a neutral
or slightly alkaline state (pH 6.5 or above) by applying lime.
"Maintaining soil pH at 6.5 or above minimizes the migration of
heavy metals," according to U.S. Department of Agriculture
(USDA) heavy metal specialist Rufus Chaney. "The manage-
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ment of a sludge disposal site is crucial in determining how
much of a hazard the sludge will be. Even a good sludge
can cause heavy metals problems if there isn't proper pH
management."
Unfortunately, little control currently exists over either
sludge quality or its management. Despite enthusiasts' claims,
there is no guarantee that safe sludge will be put on the land,
or that there will be proper site management. This creates an
opportunity for a wealth of abuses both on farms and home
gardens.
EPA case studies confirm that actual application practices
seldom follow recommended controls. One survey found that
only 5 out of 15 communities met USDA interim land-
spreading criteria; 4 of the violators grossly exceeded the
recommended cadmium limits. Another study of 25 sludge
spreading sites found that none of the farmers sampled the
content of the sludge before putting it on crops, and only a
handful monitored the soil pH.
The story is even worse for home gardeners who unwittingly
are spreading "natural" fertilizers loaded with heavy metals on
their vegetable plots. Treated urban sludges such as Milwaukee's
"Milorganite" and Chicago's "Nu-Earth," for example, contain
inordinately high amounts of cadmium. Milorganite averages
around 112 ppm cadmium, and yet it is widely sold for garden
application. Ironically, home farmers who grow their own
"organic" vegetables are likely to suffer the most.
WHAT WE CAN DO ABOUT IT
Why are heavy metals and toxic organics in sludge in the first
place? One important reason is that industries often are big
users of municipal wastewater treatment systems. On the
average, they contribute about 40 percent of what flows into an
urban sewage plant. Since industrial chemicals and metals are
largely responsible for the major environmental complications
caused by sludge, it makes sense to attack the problem head on
— at the source. Such an approach is called pretreatment.
Extracting contaminants before they mix with residential
sewage should significantly purify many sludges, and conse-
quently should decrease the environmental risks of all dis-
posal methods.
A vigorous pretreatment program, while not the complete
answer, is the only way to make more sludges acceptable for
land application. EPA currently is writing pretreatment stan-
dards for seven types of industries that discharge toxins and
heavy metals into the municipal sewage system. By 1981 such
standards will cover 21 major types of industries and will affect
over 50,000 companies. The first seven standards were to have
been issued by the beginning of July, 1977, but are several
months behind schedule.
It also is imperative to develop ways to control sludge land-
spreadifig to ensure sites are properly maintained and applica-
tion rates are adequately limited. Such management controls
can be achieved both by state and federal regulations. Long-
awaited federal guidance is on the horizon as a result of the
Resource Conservation and Recovery Act of 1976. EPA's Office
of Solid Waste currently is developing minimum criteria for the
landspreading of sludge that will define acceptable practices.
These criteria, due in by October, 1977, must be met by all
state solid waste disposal programs. If a state refuses to comply
with them, citizen suits can force it into action.
CITIZENS AND SLUDGE
We all have a large stake in sludge from start to finish: we
create it and at the other end we pay for its disposal with our
health, our tax dollars, and the integrity,of our environment.
Given that many states and communities will be making impor-
tant sludge decisions in the coming years, it is important for
citizens to familiarize themselves with the problems and actively
participate in the debate and its solutions.
There are a number of things you can do:
At home. Inform yourself about sludge and spread the word.
For more information write to: Systems Management Division
(AW-464), Office of Solid Waste, U.S.< Environmental Protec-
tion Agency, Washington, D.C. 20460. j
— If you use sludge fertilizer (other than your own home com-
posted type) on your home vegetable' garden, make sure you
know what's in it. It probably would ;be best not to grow any
food in the sludge-treated garden, but at least stop growing
the worst metal absorbers — leafy vegetables (i.e. spinach,
lettuce, swiss chard), and root crops. Make certain your soil is
above pH 6.5; lime it if necessary.
In your community. Organize a group of concerned citizens and
put sludge on the agenda at your next city council meeting.
— Find out where your sewage sludjge goes, and which local in-
dustries use the municipal wastewater treatment system.
Common high polluters include the viscose rayon, vulcanized
rubber, and paper industries (which discharge excess zinc) and
the metal plating industry (which contributes copper, nickel,
cadmium, and chromium).
— If local produce is grown on sludge-fertilized soil, find out
what is in the sludge and what, if any, management procedures
are followed. If your city officials do not know the answers,
prod them to find out.
— If your community will be making sludge-related decisions.
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ask hard questions about the safety of the proposed pro-
gram. Try to make certain all of the risks and merits are taken
into account.
— Your community has the tools for making informed de-
cisions; use them. EPA offers communities general assistance in
assessing sludge disposal options, as well as guidance on proper
sludge management and control. Have your city or county
officials contact your regional EPA office for information. For
specific advice, turn to USDA. For a nominal fee, USDA's Agri-
cultural Extension Service often will analyze soil/sludge samples
and give site-specific assistance to communities that landspread
sludge. Your local government people should contact the
county extension agent for assistance.
* establishes adequate management controls if food-chain
application is allowed. This includes setting specific low limits
on how much heavy metals and nitrogen can be applied, pH
control of 6.5 or above, and a conservative ceiling on the total
amount of heavy metals that can accumulate in the soil. Provi-
sions for adequate monitoring should be included.
— Push for a strong pretreatment program both with state
planners and your state officials.
On the national scene. Write ^to your congressman and/or
senator expressing your support of a vigorous pretreatment
program, and ask them to inquire on your behalf what EPA is
doing in this area.
At the state level. Become actively involved in the sludge
debate and voice your concerns to responsible state officials.
States must develop a comprehensive sludge policy as part ot an
overall solid waste management plan required under the Re-
source Conservation and Recovery Act of 1976. You have a
legal right to be part of that planning process, so take advantage
of it.
— Insist that state planners address the sludge issue thoroughly
and responsibly. Tell them you want a policy that:
• puts primary emphasis on applying sludge to devastated
areas such as stripmines and gravel pits and provides that the
land will not be used for food chain crops if large quantities of
sludge are applied.
• encourages the use of sludge on ornamental lands such
as golf courses, rights of way, flower gardens and parks. Even
here there should be limits on the amount of sludge applied so
as to avoid water contamination.
• encourages establishing "sludge farms" for careful dis-
posal of the maximum amount of sludge the environment can
safely tolerate. This land would have to be "dedicated," or
legally restricted for sludge disposal, to ensure that food chain
crops are not grown.
• discourages landspreading sludge on food-chain crops, and
forbids putting it on leafy green vegetables, tobacco, and root
crops.
It is time that government and citizens alike focus our atten-
tion on this obscure — but important — issue and find better
ways of dealing witn sludge berore it poisons us and our
environment. Let's make certain we are making the best
possible decisions about sludge, the much-ignored effluent
of affluence.
For further reading: "Municipal Sludge: What Shall We Do With
It?" by the League of Women Voters (pub. no. 627, 50 cents).
Contact LWV Education Fund, 1730 M Street, N.W., Washing-
ton, D.C.20036.
EAF has detailed fact sheets on specific sludge problems
and promises.
The Environmental Action Foundation is a non-profit, tax-exempt
citizens' organization devoted to research and education on a variety
of environmental issues.
The Solid Waste Project is an information clearinghouse and
citizens'.communication network. The Garbage Guide is produced by
the project staff: Kay Pitcher. Elizabeth Tennant, and Merchant
Wentworth.
This project has been financed in part with federal funds from the
Environmental Protection Agency under the grant number T90551-
01-0. The contents do not necessarily reflect the views and policies of
the Environmental Protection Agency nor does mention of trade
names or commercial products constitute endorsement or recommen-
dation for use.
Reprinted with permission of the
Environmental Action Foundation.
U.S. EPA, 1979.
SW-805
environmental action foundation
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