Remediation of PAH-Contaminated Soils and Sediments: A ...

Chemical Techniques for Enhancing PAH
Degradation
In situ chemical oxidation is a process where oxidants (ozone, hydrogen
peroxide, hypochlorites, chlorine and chlorine dioxide) are injected into the
contaminated soil to convert PAHs to more stable and less mobile forms (Figure
10) and/or to provide an oxygen source for microbes (coupled with
bioremediation). It is important to consider soil properties and injection method
when choosing the appropriate oxidant. There are several drawbacks to this
process including, but not limited to:
� Oxidant introduction can negatively impact subsurface soils
� Decreased soil permeability (colloid formation)
� Release of previously sorbed metals to groundwater resources
� Toxic byproduct production
� Heat and gas production
� Logistics of handling and storing oxidizing chemicals
Figure 10. Injection of potassium permanganate for oxidation of PAHs in
contaminated soils. Source: http://sve.ucdavis.edu/AlternativesDesc.htm
Bioremediation processes are efficient and economically feasible remediation
strategies but tend to be slow, and have shown limited capacity to degrade HMW
PAHs (Wilson and Jones, 1993; Lundstedt et al., 2003). The introduction of a
strong chemical oxidant into the soil can overcome some of the limitations
60