United States Office of Solid Waste and EPA 542-F-01-003

Environmental Protection Emergency Response April 2001

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

www.cluin.org

A Citizen’s Guide

to Thermal Desorption

gases

gas

collection

equipment

desorber

cleaned soil

tested for

pollution

clean air

released

harmful

chemicals

disposed

clean soil polluted soil disposed of safely

or cleaned using

another method

returned to site

polluted soil

  EPA uses many methods to clean up pollution at Superfund and other sites. If you live, work, or go to school

near a Superfund site, you may want to know 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.

  	
 
	


Thermal desorption removes harmful chemicals from soil and other materials (like sludge and

sediment) by using heat to change the chemicals into gases. These gases are collected with

special equipment. The dust and harmful chemicals are separated from the gases and disposed of safely. The clean soil is returned to the site. Thermal desorption is not the same as

incineration, which uses heat to destroy the chemicals.


 
  
	

Thermal desorption uses equipment called a desorber to clean polluted soil. Soil is excavated and placed in the desorber. The desorber works like a large oven. When the soil gets

hot enough, the harmful chemicals evaporate. To get the soil ready for the desorber, workers

may need to crush it, dry it, blend it with sand, or remove debris. This allows the desorber to

clean the soil more evenly and easily.
2

Thermal desorption systems can clean over 20 tons of polluted soil

per hour. The time it takes to clean up a site using thermal desorption

depends on:

• the amount of polluted soil

• the condition of the soil (Is it wet or dry? Does it contain a lot of debris?)

• type and amounts of harmful chemicals present

Cleanup can take only a few weeks at small sites with small amounts of chemicals. If the site

is large and the chemical levels are high, cleanup can take years.



	


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.

During each step of the process, workers use special equipment to control dust from the soil

and collect harmful gases that are released to the air. The polluted gases are separated from the

clean air using gas collection equipment. The gases are then changed back into liquids and/or

solid materials. These polluted liquids or solids are disposed of safely.

Before returning the cleaned soil to the site, workers may spray it with water to cool it and

control dust. If the soil still contains harmful chemicals, workers clean it further by placing it

back in the desorber. Or they may try other cleanup methods instead. If the soil is clean, it is

returned to the site. If the soil is not clean, it is sent to a landfill.

 	
 
	
 

Thermal desorption has been used at many sites over the years. EPA makes sure that materials

are handled safely at each stage of the process. EPA tests the air to make sure that dust and

gases are not released to the air in harmful amounts. EPA also tests the soil to be sure it is clean

before it is returned to the site. All equipment must meet federal, state, and local standards.

  	
 
	


Thermal desorption works well at sites with dry soil and certain types of pollution, such as fuel oil,

coal tar, chemicals that preserve wood, and solvents. Sometimes thermal desorption works where

some other cleanup methods cannot—such as at sites that have a lot of pollution in the soil.

Thermal desorption can be a faster cleanup method than most. This is important if a polluted site

needs to be cleaned up quickly so it can be used for other purposes. The equipment for thermal

desorption often costs less to build and operate than equipment for other cleanup methods using

heat. EPA has selected thermal desorption to clean up 59 Superfund sites.

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.