REDUCTIVE DECHLORINATION OF PCB-CONTAMINATED RAISIN RIVER SEDIMENTS BY ANAEROBIC MICROBIAL GRANULES

A polychlorinated biphenyl (PCB)-dechlorinating anaerobic microbial co nsortium, developed in a granular form, demonstrated extensive dechlor ination of PCBs present in Raisin River sediments at room (20 degrees to 22 degrees C) and at a relatively low (12 degrees C) temperature. H ighly chlorinated PCB congeners were dechlorinated and less chlorinate d compounds were produced. The homolog comparison showed that tri-, te tra-, penta-, hexa-, and heptachlorobiphenyl compounds decreased signi ficantly, and mono- and dichlorobiphenyl compounds increased. After 32 weeks of incubation at 12 degrees C, the predominant less chlorinated products included 2-, 4-, 2-2/26-, 24-, 2-4-, 24-2-, 26-2-, and 26-4- CB. Among these, 24- and 24-2-CB did not accumulate at room temperatur e, suggesting a further dechlorination of these congeners. Predominant ly meta dechlorination (i.e., pattern M) was catalyzed by the microbia l consortium in the granules. Dechlorination in the control studies wi thout granules was not extensive. This study is the first demonstratio n of enhanced reductive dechlorination of sediment PCBs by an exogenou s anaerobic microbial consortium. (C) 1997 John Wiley & Sons, Inc.