Anaerobic dechlorination of aroclor 1242 as affected by some environmental conditions

Abstract

The effect of electron acceptors and biphenyl on reductive dechlorination was investigated using the commercial polychlorinated biphenyl mixture Aroclor 1242 and sediment microorganisms from the Hudson River. Polychlorinated biphenyl‐ (PCB‐) free sediments spiked with the Aroclor at 700 μg/g and anaerobically incubated for six months, with and without biphenyl enrichment, showed that dechlorination was most advanced with CO2 without biphenyl enrichment. A small amount of methane was detected. However, methane production per se was not essential for dechlorination, because addition of the inhibitor of methane production, 2‐bromoethane sulfonate, did not affect dechlorination. On the other hand, dechlorination was inhibited partly by sulfate and completely by nitrate. Biphenyl enrichment initially inhibited dechlorination under both methanogenic and sulfidogenic conditions.

Reductive Dechlorination of Polychlorinated Biphenyls in St. Lawrence River Sediments and Variations in Dechlorination Characteristics

“…Recently Ye et al (13) were able to separate two physiologically distinct groups of dechlorinating microorganisms on the basis of their sensitivity to heat and ethanol treatments. Dechlorination products were also found to vary with the supply of Hz (12,14) or pyruvate (15), which also suggested the activity of different dechlorinating populations.…”

“…28, No. 12, 1994 different dechlorinating competence; under identical incubation conditions, microorganisms from the St. Lawrence River produced only 2,5-chlorobiphenyl (2,5-CBP) from 2,4,5-CBP whereas Hudson River microorganisms yielded predominantly 2,4-CBP and a small proportion of 2,5-CBP (12). Recently Ye et al (13) were able to separate two physiologically distinct groups of dechlorinating microorganisms on the basis of their sensitivity to heat and ethanol treatments.…”

Kinetics of Polychlorinated Biphenyl Dechlorination by Hudson River, New York, Usa, Sediment Microorganisms

“…Although this process preferentially removes metaand para-chlorines (Cls), not all Cls at these positions are removed, because their removal is determined by the pattern of chlorination on the biphenyl ring rather than by the substitution position per se [1]. In laboratory dechlorination studies of Aroclor 1242 using Hudson River (New York, USA) microorganisms, dechlorination removed approximately 20% of Cls from the original mixture, although the total metaand para-Cls account for 55% [2,3].…”

Microbial Degradation of PCBs in Contaminated Sediments

“…(Zwiernik et al, 1998). Nitrate-reducing conditions were completely inhibitory to Aroclor 1242 dechlorination (Rhee et al, 1993b). Recently, Ye et al (1992Ye et al ( , 1995 provided evidence that sulfate-reducing sporeformers and methanogens may be responsible for specific meta and para dechlorination patterns, respectively.…”