6160
United States
Environmental Protection
Agency
Office of Emergency Fall 1986,
and Remedial Response SF/AT-/87-';
Washington, DC 20460
x°/EPA Superfund
Alternatives for
Managing Hazardous
Waste
THREE
BASIC
OPTIONS
In 1980, Congress passed a law aimed at
protecting us, and our environment, from the
effects of disposing of hazardous waste
illegally or improperly. This law is known as
SUPERFUND because it provides a special
pool of money to be used just for the
purpose of helping clean up hazardous waste
sites around the country. The Environmental
Protection Agency (EPA) is in charge of
making SUPERFUND work.
At most Superfund sites, the EPA must deal
with not just one type of hazardous waste
but with many. Often the waste is not in
containers but is mixed with the soil or the
water. Also, at the time a hazardous waste
site is discovered, no one may know what
kind of hazardous waste is present, how
much there is, or how long it has been at the
site.
For these reasons, managing hazardous waste
at Superfund sites has proven to be a difficult
job. The EPA has found that there are
several methods which can be used to clean
up hazardous waste, depending on the
particular situation. One of the most
common methods is LAND DISPOSAL.
Land disposal means that the hazardous
waste is placed in a pit or landfill that has
been lined and covered to prevent waste from
leaking out and water from getting in. Land
disposal also includes disposing of liquid
hazardous waste in specially lined ponds
called "surface impoundments."
But, although land disposal is common and
appears to be inexpensive, it is not always the
best technique. The waste in the landfill may
still be hazardous and may, in some cases,
eventually leak out.
Recently, scientists, citizens, 'and government
officials have expressed a desire to see
hazardous waste managed in a manner that is
more permanent than land disposal. In
response, Congress passed a law in 1984 that
will, by 1990, severely limit how much and
what type of hazardous waste can legally be
placed in the ground or put in surface
impoundments. Also, the Superfund
Amendments and Reauthorization Act of
1986 states that permanent cleanup methods
are to be favored over land disposal. In
preparation for the future, EPA has started
new programs to find, test, and encourage
ALTERNATIVES to land disposal.
The purpose of this fact sheet is to present
some ALTERNATIVES to land disposal,
describe how they work, and explain why
they are better choices for dealing with
hazardous waste in some cases.
DESTROY
IMMOBILIZE
SEPARATE
U.S. Environmental Protection Agency
Region 5, Library (5PL-16) ' ..
230 S. Dearborn Street, Roo* 1670
Chicago, IL 6tJ604
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THREE BASIC OPTIONS
When an engineer or scientist is faced with a
hazardous waste problem at a Superfund site,
there are three basic treatment options to
choose from.
• Option 1. DESTROY the waste to get rid
of it completely or CHANGE the waste
chemically to make it harmless.
• Option 2. IMMOBILIZE the waste so
that, even though it may still be
hazardous, it will be less likely to move
into the air, soil, or water.
• Option 3. SEPARATE the waste from the
soil, water, or other waste so that the
contaminants are easier to destroy or
immobilize. Decide if any of these wastes
can be reused.
In studying these options, the engineer or
scientist examines ALTERNATIVE ways
to manage hazardous waste. Some of these
alternatives are described below. It is
important to remember that not all
techniques can be used in all situations
because of the variety and complexity of
Superfund sites. Often many techniques
must be used together to thoroughly treat
the hazardous waste, and even when
alternative techniques can be used, land
disposal may still be necessary to safely
handle the residues, or what is left after
treatment.
If the hazardous waste is thoroughly treated,
it is less likely that the problem will merely be
moved from one place to another. We make
sure, for instance, that in solving a problem
with contaminated soils we don't create a
problem with contaminated water. It may
cost more money initially to thoroughly treat
a hazardous waste, but in most instances and
in the long run, we believe the price of the
permanent solution will be justified.
WAYS TO DESTROY OR CHANGE WASTES
When we DESTROY or
chemically CHANGE hazardous
waste, the waste actually turns
into some other material that is not harmful
—or not as harmful—to people or to the
environment. Even when we use a technique
that destroys, or nearly destroys, the
hazardous waste, smaller amounts of residue
are usually left which must be disposed of.
Two of the most common methods used to
DESTROY or change hazardous waste are
described below.
THERMAL TREATMENT
For centuries, people have used heat,
usually in the form of fire, to get rid of
waste. In the right conditions, and if
properly controlled, heat—or THERMAL
TREATMENT—is still a good technique
and can be used on hazardous waste.
There are many different kinds of thermal
treatment. Some of these use flame to
burn the waste, and others heat the waste
to extremely high temperatures without a
Mobile Incinerator
Hazardous
Waste
Hazardous
4 4* 1 W\ Gases
*/
Gases to
Additional
Treatment
or Release
Ash to
Additional
Treatment
or Disposal
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flame. Types of processes that do not use
a flame to heat the waste are called
"pyrolysis," "plasma arc," "fluidized bed
treatment," and "infrared treatment."
The most common thermal treatment is
incineration, in which hazardous waste is
burned using a flame at high temperatures.
Special incinerators have been designed to
burn liquid, solid, and gaseous wastes.
When a hazardous waste is incinerated,
ash and gas are usually formed. The ash
may still be considered hazardous.
However, it is usually much easier to
handle than the original material that was
burned, primarily because the ash takes up
less space than the original waste and
because it is solid. If the gases created
when a waste is burned are still hazardous,
they can be captured with air pollution
control devices and burned or treated
again. This helps prevent hazardous
chemicals from being released into the air.
Incineration can be costly because the
equipment is expensive and because it
requires a lot of energy. Its advantages are
that it greatly reduces the volume of the
waste and often completely destroys the
hazardous chemicals.
Currently, if waste at a SUPERFUND site
is to be burned, it is usually removed from
the site and taken to the incinerator. In the
future, mobile incinerators, which can be
moved from one hazardous waste site to
another, may be used more often.
• NEUTRALIZATION
When we eat too much of certain kinds of
foods, we get what the commercials call
"acid indigestion." The solution to this
problem is to take bicarbonate of soda,
which NEUTRALIZES the acid in our
stomachs. Certain kinds of hazardous
wastes can be treated in the same way. If
they are acid wastes, an alkali (like
bicarbonate of soda) can be mixed with
the waste. This causes a chemical change
to occur in the waste, making it harmless,
or nearly so. If the waste is alkaline
(sometimes called "basic"), an acid can be
added to achieve the same result.
The diagram below shows how a
neutralization process works. Usually, two
tanks are used—the first to begin the
neutralization process and the second to
refine it.
Neutralization
Neutralizing
Agent '
Hazardous
Waste
REFINING TANK
Water to
Additional
Treatment
or Disposal
WAYS TO IMMOBILIZE WASTE
When we IMMOBILIZE
hazardous waste, our goal is to
put the waste into a solid form so
that it is easier to handle and less likely to
move into the surrounding environment.
Immobilization is useful for wastes that
might seep into underground water or might
be carried by rainwater into the environment.
It is especially useful on certain metals which
cannot be destroyed. Once a waste has been
immobilized, the solid waste must be properly
disposed.
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STABILIZATION/SOLIDIFICATION
The stabilization/solidification process can
be compared to the preparation of
sweetened gelatin. When gelatin is added
to flavored sugar water, the gelatin
dissolves. Together the gelatin and the
sugar are "fixed" in the water. When the
gelatin sets, it "solidifies" the liquid and
everything in it. When applying these
principles to hazardous waste, engineers
and scientists mix solidifying agents such
as fly ash or cement with the hazardous
waste, which both "fixes" and "solidifies"
the material. This serves three purposes.
First, the ash or cement can react
chemically to "fix" the hazardous waste.
Second, if necessary, the ash or cement is
made into a solid block that can be
permanently sealed and stored more easily
than a liquid can. Third, once the
hazardous waste is chemically bound to
the ash or cement, it is less likely to be
washed into the environment by rainwater.
Stabilization/Solidification
Solidifying
Agent -
Hazardous ,
Waste
MIXING TANK
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SETTING TANK
LANDFILL
WAYS TO SEPARATE WASTE
If we can SEPARATE one
hazardous waste from another, or
if we can take a hazardous waste
out of the material it has contaminated, it is
easier to destroy, immobilize, or bury the
waste. Separation can, in some cases, allow
the waste to be recycled for other industrial
processes. Often water, soils, or air that were
contaminated by hazardous waste can also be
reused after being separated from the
hazardous chemical. Separating the waste
sometimes involves changing the waste from
one form (solid, liquid, or gas) to another.
Several techniques used to SEPARATE
wastes are described below.
• AIR STRIPPING/STEAM STRIPPING
Certain kinds of chemicals that tend to
evaporate easily are called "volatiles."
They can be removed from water using a
technique called AIR STRIPPING. Air
stripping literally forces the chemicals out
of the water by pushing air through it,
causing the chemicals to be mixed with the
air. If the mixture of air and chemicals
that results is still hazardous, it can be
further treated before being released.
Some chemicals that cannot be released by
air stripping are released when heat is
applied. This process is called STEAM
STRIPPING, and it is similar to air
stripping. Steam is pushed into the waste
to raise the temperature and help release
the chemicals from the water or steam.
Air Stripper
Hazardous
Liquid
Air Emission
to Additional
Treatment or
Reie
Liquid
to Additional
Treatment or
Discharge
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• PRECIPITATION
In treating some hazardous waste, a process
can be used that mimics the way rain falls
from the sky. Rain is created when drops
of water form around thiy p'articles of dust.
When enough cfrops form around the ;
particle of dust^ it isTqo heavy to remain a
part of the cJ6ud','£n^ftf4lWt$ the'ground
as rain or "precipitation.'* Wh'eria'"'7" '
PRECIPITATJONYne'thotf &' iStsea1 to tr&t
hazardous w^sje^ ioatgr^lj^\gtB^l!Lattr?ct
the hazardous chemicals is placed into the
liquid hazardous waste. The hazardous
chemicals bind to the material and form
large particles called "floe."
If the floe is distributed throughout the
liquid, it can be filtered. If the floe is
heavier than the liquid, it will sink to the
bottom. The "sludge" that is formed can
then be separated from the liquid. This is
the process illustrated in the diagram. This
separation process reduces the volume of
material that must be further treated,
destroyed, or immobilized.
Precipitation
Hazardous
Waste
Precipitating \ ""•
•Agent
Screen
Mixing
Tank
Settling
Tank
?&mmmmmm
Sludge to
Additional
Treatment
or Disposal
Liquid to
Additional
Treatment or
Discharge
• SOIL WASHING, ANJ) FLUSHING
If soil is contaminated with a chemical
that'caffbe eS^dfs*Solv£dr"SOIL
WASHING or SOIL FLUSHING can be
useg* as a treatment. :The equipment used
in SblL WASHING is>ot mucji different
from a standard household washihg
machine—only larger. The contaminated
soil;-and a cleaning liqujd a"re mixed in a
tanfL The hazardous'chemicals- dissolve in
the cleaning liquid, which removes the
chemicals from the soil. The liquid is then
collected and treated. SOIL FLUSHING is
similar to SOIL WASHING except that it
occurs right in the ground. Liquid is
passed through the soil and collected,
usually in pipes or wells at the base of the
contaminated area. The liquid is sent
through the soil again and again until the
soil is clean enough to leave in place.
Soil^Washing
Cleaning
Liquid
Contaminated
Soil
Soil to
Additional
Treatment or
Disposal
Liquid to
Additional
Treatment or
Disposal
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CARBON ADSORPTION
Some people put charcoal filters on their
faucets at home to purify their drinking
water. These charcoal filters function
almost exactly like large CARBON
ADSORPTION tanks that treat gaseous
and liquid hazardous waste. Air and water
that contain hazardous chemicals are
allowed to move through tanks containing
carbon that has been "activated" to better
treat the waste. The carbon filters the
waste out of the air or water in two ways.
First, the carbon can chemically combine
with the waste. Second, it can catch
hazardous particles just as a fine wire
mesh catches grains of sand.
After a carbon adsorption process has
been used, the carbon will have high
amounts of hazardous chemicals in it. It
can then be disposed of through some
other technique or cleaned and reused.
Carbon adsorption is often used as the
final process, when a number of treatment
processes are used. When carbpn
adsorption is used as the final process, the
treated water is-safe to drink and the
treated air is safe enough"to release.
Carbon Adsorption
Contaminated
Liquid
Activated
Carbon
Carbon to
Additional
Treatment
or Disposal
THE USE OF ALTERNATIVES TO LAND DISPOSAL
Over time, EPA will use these and other
methods more often to manage hazardous
wastes at SUPERFUND sites. Variations on
these techniques will be tested and brought
into use, and new, more efficient, less costly
techniques invented. EPA has begun the
Superfund Innovative Technology Evaluation
(SITE) Program to help speed these
processes. The SITE program will help
demonstrate that alternative technologies can
work at Superfund sites.
If you are interested in alternative ways of managing hazardous wastes and would like to learn
more about what EPA is doing to promote these, please contact the Superfund Hotline at
1-800-424-9346.
U.S. Environmental Protection Agency
Region 5, Library (5PL-16)"
230 S. Dearborn Street, Room 1670
Chicago, IL 60604
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