United States
Environmental Protection
Agency
Office of Solid Waste and
Emergency Response
(5102G)
EPA542-F-01-013
April 2001
www.epa.gov/superfund/sites
www.cluin.org
&EPA A Citizen's Guide
to Chemical Oxidation
The Citizen's Guide Series
EPA uses many methods to clean up pollution at Superfund and other sites. Some, like chemical oxidation, are
considered new or innovative. Such methods can be quicker and cheaper than more common methods. If you
live, work, or go to school near a Superfund site, you may want to learn more about cleanup methods. Perhaps
they are being used or are proposed for use at your site. How do they work? Are they safe? This Citizen's Guide
is one in a series to help answer your questions.
What is chemical oxidation?
Chemical oxidation uses chemicals called oxidants to destroy pollution in soil and ground-
water. Oxidants help change harmful chemicals into harmless ones, like water and carbon
dioxide. Chemical oxidation can destroy many types of chemicals like fuels, solvents, and
pesticides.
How does it work?
Chemical oxidation does not involve digging up polluted soil or groundwater. Instead, wells
are drilled at different depths in the polluted area. The wells pump the oxidant into the
ground. The oxidant mixes with the harmful chemicals and causes them to break down.
When the process is complete, only water and other harmless chemicals are left behind.
recirculated mixture of oxidants,
groundwater, and chemicals
I oxidant
0)
ground surface
groundwater
level
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For more
information
write the Technology
Innovation Office at:
U.S.EPA(5102G)
1200 Pennsylvania
Ave., NW
Washington, DC 20460
or call them at
(703) 603-9910.
Further information also
can be obtained at
www.cluin.org or
www.epa.gov/
superfund/sites.
To clean up a site faster, oxidants can be pumped in one well and out another well. This ap-
proach helps mix the oxidant with the harmful chemicals in the groundwater and soil. After the
mixture is pumped out, it is pumped back (recirculated) down the first well. As pumping and
mixing continues, more polluted soil and groundwater are cleaned up.
It can be hard to pump oxidants to the right spots in the ground. So before drilling starts, EPA
must study the conditions underground by testing the soil and groundwater. Where is the pollu-
tion? How will the oxidant spread through the soil and groundwater to reach it?
The most common oxidant to clean up pollution is hydrogen peroxide. Another is potassium
permanganate, which is cheaper. Both oxidants are pumped as liquids. And both have advan-
tages depending on the site. Ozone is another strong oxidant, but because it is a gas, it can be
difficult to use.
At some sites, a catalyst is used with the oxidant. A catalyst is a chemical that increases the
strength or speed of a process. For instance, if hydrogen peroxide is mixed with an iron catalyst,
it produces a strong chemical called afree radical. Free radicals can destroy more harmful
chemicals than hydrogen peroxide alone.
Chemical oxidation can create enough heat to boil water. The heat can cause the chemicals
underground to evaporate, or change into gases. The gases rise through the soil
to the ground surface where they are captured and cleaned up.
How long will it ?
The time it takes for chemical oxidation to clean up a site depend
on several factors:
• size and depth of the polluted area
• type of soil and conditions present
• how groundwater flows through the soil (How fast? Along what path?)
In general, chemical oxidation offers rapid cleanup times compared to other methods.
Cleanup times can be measured in months, rather than years.
Is chemical oxidation safe?
Chemical oxidation can be quite safe to use, but there are potential hazards. Oxidants are corro-
sive, which means they can wear away certain materials and can burn the skin. People who work
with oxidants must wear protective clothing. Some oxidants can explode if used under the wrong
conditions. Explosions can be prevented, however, through proper design of the chemical oxida-
tion system. EPA makes sure that the system is properly designed. Workers also test the soil,
groundwater, and air after chemical oxidation to make sure the site is cleaned up.
Why use chemical oxidation?
Chemical oxidation is being used at hundreds of sites across the country. It destroys pollution
underground without having to dig it up or pump it out for transport to a treatment system. This
saves time and money. Often chemical oxidation is used to clean up pollution that other methods
can't reach, like pollution deep within the groundwater. Chemical oxidiation can be used to
clean up the source of pollution. Most other methods that are used to remove the source are
very slow and more expensive.
NOTE: This fact sheet is intended solely as general guidance and information to the public. It is not intended, nor can it be relied
upon, to create any rights enforceable by any party in litigation with the United States, or to endorse the use of products or services
provided by specific vendors. The Agency also reserves the right to change this fact sheet at any time without public notice.
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