EPA 540/F-94/501
Fluid Extraction-Biological Degration Process
Institute of Gas Technology
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Fluid Extraction-Biological Degration Process Institute
of Gas Technology (15K)
ABSTRACT
Fluid Extraction-Biological Degration Process
Institute of Gas Technology
Emerging Technology Bulletin
EPA 540/F-94/501
March 1994
The Institute of Gas Technology's (IGT) fluid extraction-biological degradation
(FEBD) process is a three-step system that remediates organic contaminants from
soils. The process includes the following technologies: 1) fluid extraction
to remove the contaminants from the soil, 2) separation to transfer the pollutants
from the extract to a solvent; and 3) biological degradation to transform the
pollutants into innocuous end-products. In the fluid extraction step, excavated
soils are placed in a pressurized vessel and extracted with a recirculated stream
of supercritical carbon dioxide. During the separation stage, the extract containing
the organic contaminants are transferred to a biologically-compatible separation
solvent such as water or a water-methanol mixture. The separation solvent is
sent to the final stage of the process, where bacteria degrade the waste to
carbon dioxide and water. Clean extraction solvent is then recycled for use
in the extraction stage. The technology has been effective on soils contaminated
with gasoline, fuel oils, non-halogenated aliphatic hydrocarbons and polyaromatic
hydrocarbons (PAHs). IGT evaluated the FEBD process with soils from a Superfund
site and at three town gas sites. Approximately 85 to 99 percent of PAHs were
removed from the soils. The PAHs were biologically changed at short hydraulic
retention times.
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Posted February 26, 1999
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