![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
The reductive dechlorination of polychlorinated biphenyls (PCBs) in enriched medium with an anaerobic chlorophenol (CP)‐adapted consortium was investigated in order to define the conditions which control PCB dechlorination in naturally anaerobic environments. The fastest observed dechlorination rates of 2, 3, 4‐CB or 2, 3, 4, 5 ‐CB (1 mg/L concentration) to the intermediate products dichlorobiphenyl or trichlorobiphenyl were 0.15 and 0.14 mg/L/day at 30°C and pH7.0. For PCB congeners with higher chlorine content (2, 2’, 4, 4’, 6, 6'‐CB, 2, 2’, 3, 4, 4’, 5, 5'‐CB), the dechlorination rate dropped sharply to below 0.01 mg/L/day. The congeners 2, 2’, 3, 3’, 4, 4'‐CB and 2, 2’, 3, 3’, 4, 4’, 5, 5'‐CB were not dechlorinated to lower chlorinated congeners even after a 100‐day incubation period. The addition of electron donors did not enhance the dechlorination rates for 2, 3, 4‐CB, 2, 3, 4, 5‐CB or 2, 2’, 4, 4’, 6, 6'‐CB. For these three congeners, dechlorination was enhanced under methanogenic conditions but inhibited under sulfate‐reducing or denitrifying conditions.