Remediation of organochlorine pesticides (OCPs) contaminated soil by successive hydroxypropyl-β-cyclodextrin and peanut oil enhanced soil washing-nutrient addition: a laboratory evaluation

Problems associated with organochlorine pesticides (OCPs)-contaminated sites have received wide attention. To address the associated environmental concerns, innovative ex situ techniques are urgently needed. As regards long-term contamination by OCPs in Wujiang region, China, we investigated the feasibility of a cleanup strategy that employed hydroxypropyl-beta-cyclodextrin (HPCD) and peanut oil to enhance ex situ soil washing for extracting OCPs, followed by the addition of supplemental nutrients to the residual soil. Elevated temperature (50 A degrees C) in combination with ultrasonication (35 kHz, 30 min) at 50 g L-1 HPCD and 10 % peanut oil were effective in extracting, and therefore washing, the OCPs in soil. Ninety-three percent of total OCPs, 98 % of dichlorodiphenyltrichloroethanes, 93 % of chlordane as well as 85 % of Mirex were removed from soil after three successive washing cycles. Treating the residual soil with nutrients addition for 12 weeks led to significant increases (p < 0.05) in the average well color development obtained by the BIOLOG Eco plate assay, Shannon-Weaver index, Simpson index, and EC50 ecotoxicological evaluation compared with the controls. This implied that this cleanup strategy at least partially restored the microbiological functioning of the OCPs-contaminated soil and has the advantage of being an environmental-friendly technology. The ex situ cleanup strategy through HPCD and peanut oil enhanced soil washing followed by nutrients addition could be effective in remediation of OCPs-contaminated soil.