United States
                Environmental Protection
                           Office of Solid Waste and
                           Emergency Response
October 2001
A  Citizen's Guide
to Solvent Extraction
 The Citizen's Guide Series
 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.
                                                                ime   i
                  What  is 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.

                  How does  it work?
                  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.
                                                                     polluted material
                                                                  (cleaned up by a second
                                                                 method or place in a landfill)

For  more
write the Technology
Innovation Office at:

1200 Pennsylvania Ave.,
Washington, DC 20460

or call them at
(703) 603-9910.

Further information also
can be obtained at
www.cluin.org or
                          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

                          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

                          Is  solvent  extraction safe?
                          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.
                             How long will it take ?
                            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.
Why  use  solvent  extraction?

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
                          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.