United States Office of Solid Waste and EPA 542-F-01-013

Environmental Protection Emergency Response April 2001

Agency (5102G) www.epa.gov/superfund/sites

www.cluin.org

A Citizen’s Guide

to Chemical Oxidation

  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.

polluted groundwater

groundwater

level

oxidant

ground surface

recirculated mixture of oxidants, 

groundwater, and chemicals

wellwell

  	
 


Chemical oxidation uses chemicals called oxidants to destroy pollution in soil and groundwater. 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.

 	  

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.
To clean up a site faster, oxidants can be pumped in one well and out another well. This approach 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 pollution? 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 advantages 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 a free 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.

 	
 
 	

Chemical oxidation can be quite safe to use, but there are potential hazards. Oxidants are corrosive, 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 oxidation 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.

 	 	
 


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. 2



	


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.

The time it takes for chemical oxidation to clean up a site depends

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.