Degradation of Aroclor 1242 in a single-stage coupled anaerobic/aerobic bioreactor

Degradation of Aroclor 1242 was studied in granular biofilm reactors with l imited aeration. An aerobic biphenyl degrader, Rhodococcus sp. M5, was used to supplement a natural bacterial population present in a "bioaugmented" r eactor, while the "non-bioaugmented" reactor only contained natural granula r sludge. The bioaugmentation, however appeared to have no effect on the re actor performance. Aroclor measurements showed its disappearance in both re actors with only 16-19% of Aroclor recovered from the reactor biomass and e ffluent. Simultaneously, a chlorine balance indicated that dechlorination o ccurred at a specific rate of 1.43 mg PCB (g volatile suspended solids) (-1 ) d (-1), which was comparable to the observed rate of Aroclor disappearanc e. Intermediates detected in both reactors were biphenyl, benzoic acid, and mono-hydroxybiphenyls. This suggests that a near-complete mineralization o f Aroclor can be achieved in a single-stage anaerobic/aerobic system due to a combination of reductive and oxidative degradation mechanisms. Crown Cop yright (C) 2001 Published by Elsevier Science Ltd. All rights reserved.