Remediation and Management of Contaminated Soil - Sustainable Practices in Geoenvironmental Engineering - page 421

Contaminated soil or sediment

Screen

Oversize material

Clean water

ickener or
plate frame press

Nutrients and
microbes

Recycle water

Air

Cleaned soil or sediment for
disposal or reuse

FIGURE 11.9
Schematic of a bioslurry process.

than for in situ remediation. This type of treatment is particularly applicable for com-
pounds of low biodegradability such as SVOCs, VOCs, ordnance, pesticides, PCBs, and
PAHs of soils and sediments. Slurry methods can be used since dewatering is not required
(Figure 11.9). Bioremediation is a low-cost technology and therefore has the potential for
wide use. However, metal remediation technologies are not as developed as organic treat-
ments. Costs are in the range of $130 to 200/m 3 (FRTR, 2007). After treatment, water must
be separated from the solids and may require subsequent treatment.
Surfactants can be added to enhance contaminant solubility or the natural bacteria could
be stimulated to produce natural biosurfactants. The latter approach, which was investi-
gated for an oil- and heavy metal-contaminated harbor soil (Jalali and Mulligan, 2008) has
shown potential. Results showed that over the 50-day experiment, nutrient amendments
enhanced biosurfactant production to up to three times their critical micelle concentration
(CMC). Limiting the inorganic source of nitrogen showed an enhancement of biosurfac-
tant production by 40%. The biosurfactants produced by the indigenous soil microorgan-
isms were also able to solubilize 10% of TPH and 6% of the metal content of the soil and
enhance biodegradation of petroleum hydrocarbons.

11.5.2 Landfarming

Land farming includes mixing the surface layer of soil with the contaminated sediment
(Rittmann and McCarty, 2001) (Figure 11.10). Soil microorganisms are utilized for biodegra-
dation of the contaminants including oil sludge, wood preserving wastes, coke wastes, JP-5,
fuel oils, diesel fuel, and some pesticides (FRTR, 2007). The resulting product is compost.