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

� Straube et al. (2003) showed that the introduction of Pseudomonas
aeruginosa strain 64, a rhamnolipid-producing bacterium, enhanced the
biodegradation of PAHs in highly contaminated soil.
� Conte et al. (2005) found that humic acid can be used as an effective
surfactant for PAH desorption.
� Bogan and Sullivan (2003) reported that the addition of fulvic acid to soils
that had low humic acid/fulvic acid content greatly enhanced pyrene
mineralization by Mycobacterium austoafricanum. They also reported
slower progress in PAH sequestration in a soil with high fulvic acid
content.
Cyclodextrins: Cyclodextrins are cyclic oligosaccharides that are able to form
complexes with hydrophobic molecules. They are the product of the action of
cyclodextrin glycosytransferases on starch and are non-toxic and biodegradable
in the environment. Cyclodextrins can be added to washing waters to solubilize
PAHs and increase desorption from soil (Stokes et al., 2006).
Vegetable oil: Vegetable oil has been proposed as an economic and
environmentally friendly solvent to dissolve PAHs and has been shown to be as
effective as organic solvents like acetone and dichloromethane (Gong et al.,
2005).
Bioreactors
Treatment of contaminated sediments in a slurry phase is completed in a
bioreactor. Advantages of the slurry phase include: complete mixing of nutrients
into sediment, increased contact between microorganism and contaminant,
control (Eweis et al., 1998). Bioreactors are commercially available for this type
of treatment but are expensive. Sediment is often put into the bioreactors in
small batches; however, continuous flow operations are possible. With
treatment, the slurry is mixed with nutrients and microbial cultures and aerated.
The sediment then settles and the water is transferred to a treatment plant while
the sediment is returned to a contained area (Eweis et al., 1998). For large
quantities of sediment, this is a difficult option.
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