Comparative fate of 1,1-diphenylethylene (DPE), 1,1-dichloro-2,2-bis(4-Chlorophenyl)-ethylene (DDE), and pentachlorophenol (PCP) under alternating aerobic and anaerobic conditions.

Bacterial degradation of 1,1-dichloro-2,2-bis-(4-chlorophenyl)-ethylene (DDE) and its dehalogenated derivative 1,1-diphenylethylene (DPE) has not yet been shown and may require culture adaptation and special culture conditions. We compared the degradability of DPE, DDE, and pentachlorophenol (PCP) in aerobic/anaerobic sequenced batch reactor systems. Reactors operated under aerobic/methanogenic and aerobic/denitrifying conditions were inoculated with bacterial consortia from anaerobic granular sludge, long-term PCP- and DDE-contaminated soil, and pulp and paper waste pond sediment. The culture was gradually acclimatized to low concentrations of DPE, DDE, and PCP in defined minimal growth media with benzoate, phenol, ethanol, and formate as primary carbon sources. DDE remained refractory for 105 days, whereas DPE and PCP were degraded. This suggests that DDE is extremely recalcitrant to degradation by aromatic organochlorine-degrading bacteria from long-term polluted soils and sediments. The results confirm that the chlorination of DDE is a major biodegradation barrier for adapted bacteria under aerobic and anaerobic conditions.