Sonochemical extraction and biological treatment of pentachlorophenol contaminated wood

More than 450 million cubic feet of pentachlorophenol (PCP) treated wood products are discarded in municipal landfills or burned in power generating plants in the USA alone. The reported carcinogenicity of PCP is expected to result in more stringent controls and limit the disposal options of PCP treated wood. A treatment process has been developed in the laboratory scale to decontaminate PCP treated wood. In the first step of this process, the wood is chipped into small pieces. Then PCP is extracted using commercial grade ethanol. A three-step counter-current extraction under sonication removes more than 99% of the PCP from wood. In the next step, the remaining PCP is biodegraded utilizing a two stage bioreactor containing a white rot fungus. The PCP concentration in wood decreases to below detection limit (<0.01 mg kg) within 5 days. The various reactor configurations namely batch, semi-batch, and fluidized-bed were studied to minimize the treatment time. No toxic biotranformation products were detected during the biodegradation process. The extracting ethanol was regenerated for reuse. (C) 1997 Elsevier Science B.V.