A Novel Laboratory Microcosm for Cocomposting Of Pentachlorophenol Contaminated Soil

A bench-scale composting system was constructed that relied on heat generation by microbial activity in the material rather than extraneous incubation. The system gave reproducible composting temperatures and eight microcosms could be operated simultaneously. These systems were used to investigate the feasibility of cocomposting pentachlorophenol (PCP) contaminated soil as a bioremediation strategy. Laboratory cocomposting of the contaminated soil successfully reduced PCP concentrations by 80%, from 68 mg/kg to 11 mg/kg in a six-week period. Losses of PCP from compost controls were minimal indicating that removal was due primarily to biotic processes. A comparison of residual PCP levels determined by dichloromethane (DCM) extraction and a methanolic potassium hydroxide (MeOH/KOH) digest prior to DCM extraction suggested that the residual PCP was bound to the compost matrix. Recovery of PCP at the end of a composting experiment using eight vessels simultaneously using the MeOH/KOH method indicated residual concentrations of 8-10 mg/kg.