United States Office of Solid Waste and EPA 542-F-01-009

Environmental Protection Emergency Response October 2001

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

www.cluin.org

A Citiz A Citizen’s Guide s Guide

to Solvent Extraction to Solvent Extraction

  	
 


Solvent extraction (also known as chemical extraction) is a cleanup method that uses solvents

to extract or remove harmful chemicals from polluted materials. Chemicals like PCBs, oil,

and grease do not dissolve in water. Instead, they tend to stick or sorb to soil, sediment, and

sludge, making it hard to clean them up. Solvents are chemicals that can dissolve sorbed

chemicals and remove them from polluted materials.

   

Before using solvent extraction, the soil must be dug from the polluted area to be treated.

The soil is sifted to remove large objects like rocks and debris. The sifted soil is then placed

in a machine called an extractor where it is mixed with a solvent. The type of solvent will

depend on the harmful chemicals present and the material being treated. 

  EPA uses many methods to clean up pollution at Superfund and other sites. Some, like solvent extraction, 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

soil (sifted)

extractor separator

polluted material

(cleaned up by a second 

method or place in a landfill)

solvent solvent

recycled

clean soil
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.

Solvent extraction can clean up to 125 tons of soil at a site per day.

The time it takes to clean up a site depends on several factors:

• amount of polluted soil

• type of soil and conditions present (Is it wet or dry? Does it contain a lot of debris?)

• type and amounts of harmful chemicals present

Cleanup usually takes less than a year, depending on the site.

The cleaned soil is tested to make sure that the harmful chemicals have been removed. If

harmful chemicals remain, the soil is placed back in the extractor to repeat the process. Clean

soil (or sediment) can be placed back on the site.

Once the solvent dissolves the sorbed chemicals, the solvent is drained into a separator. This is

where the chemicals are separated from the solvent. The used solvent often can be recycled and

reused to clean up more soil. Otherwise, the solvents must be destroyed or disposed of in a

landfill.

If any solvent remains in the soil following treatment, the soil is heated to remove it. The heat

evaporates the solvent, changing it from a liquid to a gas. The gas is then removed from the

clean soil. As the gas cools, it changes back to a liquid solvent, which can be recycled and

reused.

 	
 
 

When properly designed and operated, solvent extraction is a safe cleanup method for soil,

sediment, and sludge. EPA tests the air while the materials are being dug. This ensures that

chemicals are not released to the air in harmful amounts. The rest of the process is usually

conducted in an enclosed area. Therefore, any harmful chemicals or solvents that evaporate can

be captured and cleaned up. Following solvent extraction, EPA tests the soil to be sure it is

clean before it is placed back on the site.

  	
 


Solvent extraction is used to clean up many chemicals that are difficult to remove from soil.

Cleanup using solvent extraction is generally quicker than methods that treat the soil in place. It

can be done at the site to avoid trucking polluted soil to cleanup facilities offsite. This saves

money on transport and disposal of the soil. In addition, the solvents can often be recycled and

reused. Solvent extraction is being used at four Superfund sites and at other sites across the

country.

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.