Environmental Engineering Reference
In-Depth Information
11.3.12 Electrokinetics
Electrokinetics is a remedial technology used to separate and extract heavy metals and
other contaminants from saturated and unsaturated soil, sludges, and sediments. It works
by inducing the migration of contaminants in subsurface soil through an imposed elec-
trical field via electroosmosis. A low voltage current is applied to initiate the migration
of contaminants. The configuration involves the application of an electrical potential
between electrode pairs implanted in the ground on each side of a contaminated soil mass
(Cauwenberghe 1997).
11.3.13 Solidification/Stabilization
Solidification/Stabilization is conducted in situ and ex situ and involves the addition
or injection of a material, such as concrete or bentonite clay to permanently immobilize
or entomb the contaminants. This technique does not remove contaminant mass—it is
designed to eliminate or minimize the potential of the contaminants from migrating and
potentially causing harm to human health or the environment.
11.3.14 Fracturing
Fracturing involves cracking dense contaminated soils or rock so other remedial tech-
nologies can work more efficiently. The cracks—called fractures —create pathways through
which contaminants can be more quickly and efficiently removed from the ground. The
fractures are created by injecting either high pressure water or air into the contaminated
zone (Figure 11.10).
11.3.15 Vitrification
Vitrification is a form of solidification/stabilization, and uses electrical power to heat
and transform contaminated subsurface soil into a glass-like substance. This process is
Air blast
Pneumatic fracturing
Air treatment system
Ground surface
Chemical evaporates and
gas rises through the soil
Sand
Clay
Fractures
FIGURE 11.10
Example of pneumatic fracturing. (From United States Environmental Protection Agency (USEPA), A Citizen's
Guide to Fracturing , EPA 542-F-01-0015, Office of Solid Waste and Emergency Response, Washington, DC, 2001e.)
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