Surfactant
Enhanced
Recovery
Description
Surfactant
enhanced recovery increases the
mobility and solubility of the contaminants sorbed to
the saturated soil matrix. Surfactants (i.e.,
surface-active agents) are the primary
ingredients of many soaps and detergents. Surfactant-enhanced recovery
injects
surfactants into contaminated groundwater. A typical
system uses an extraction pump to
remove groundwater downstream from the
injection point. The extracted groundwater is treated aboveground to
separate
the injected surfactants from the contaminants and groundwater. Once
the
surfactants have separated from the groundwater they are re-used.
Contaminants
must be separated from the groundwater using one of many treatment
methods. The
surfactants used are non-toxic, food-grade, and biodegradable.
Surfactant
enhanced recovery is used most often
where the groundwater is contaminated by dense nonaqueous phase liquids (DNAPLs). These dense
compounds, such as
trichloroethylene (TCE), sink in groundwater because they are heavier
than
water. They then act as a continuous source for contaminant plumes that can
stretch for miles within an aquifer. These
compounds may biodegrade very slowly.
They are commonly found in the vicinity of the original spill or leak
where
capillary forces have trapped them.
Limitations
and Concerns
Hydraulic
control of the surfactant and
contaminants must be maintained to prevent the spread of contamination.
Air emissions
should be controlled at
aboveground treatment.
Surfactant
enhanced recovery is often used to
complement conventional pump-and-treat systems for
removing dissolved-phase
DNAPL contamination.
Applicability
A typical
system removes and treats
VOC-contaminated groundwater. It is used primarily for removing DNAPLs,
although it could be used for removing other hydrocarbons, such as
fuel.
Technology
Development Status
Surfactant
enhance recovery has been used in the
oil industry for years. It is commercially available, although each
surfactant
should be matched with the contaminant.
Web Links
http://www.clu-in.org/download/techdrct/td-tr-2219-sear.pdf