Dechlorination of spiked PCBs in lake sediment by anaerobic microbial granules

An anaerobic microbial consortium developed in our laboratory showed dechlorination of spiked polychlorinated biphenyls (PCBs), such as Aroclor 1254 and a defined congener 2,3,4,5,6-pentachlorobiphenyl (CB) in the presence and the absence of lake sediment. Glucose and methanol were used as carbon and energy sources. Highly chlorinated congeners (containing >5 chlorines) such as penta-, hexa- and heptachlorobiphenyls were preferentially dechlorinated both in the presence and the absence of sediment with a simultaneous change in the distribution of relative amounts of tri- and tetrachlorobiphenyl congeners. The dechlorination pattern and rates observed in both sediment and sediment-free conditions were similar. In 24 weeks, almost 70% of the PCBs were dechlorinated without accumulation of any specific PCB congeners. Monochlorobiphenyls were dechlorinated at a higher rate than di- and tetrachlorobiphenyls.