Bioremediation of PCP and TPH contaminated soil in a pilot-scale field study

A one-year pilot-scale land treatment study was conducted at a site in central Mississippi to determine if soil and wood chips contaminated with two different levels of pentachlorophenol (PCP) and total petroleum hydrocarbons (TPH) could be bioremediated. One soil type came from an old timber sizer area (OTSA) and contained approximately 220 mg/kg PCP and 345 mg/kg TPH. The other soil came from an old wood treatment area (OWTA) and contained approximately 1,475 mg/kg PCP and 525 mg/kg TPH. Monthly soil samples were collected and analyzed by gas chromatography (GC) for PCP and TPH. By day 60, PCP concentrations in the OTSA manure-treated cells had decreased by 87% and TPH by 75 %, while the control cells only decreased by 16% for PCP and 28% for TPH. Addition of chicken manure to the OWTA soil provided excellent degradation of both PCP and TPH, while addition of microorganisms plus manure did not enhance degradation over the manure addition. Bioremediation appears to be a viable clean-up option for this soil. PCP degraded poorly in the OWTA soil with only a 46% decrease by day 360, while TPH concentrations decreased by 94%. Bioremediation for this soil was not recommended.