Reductive Dechlorination of Hexachlorobenzene by an Anaerobic Mixed Culture

The potential for reductive dechlorination of hexachlorobenzene (HCB) by a 1,2,3-trichlorobenzene (TCB)-adapted mixed culture was investigated. Optimal dechlorination conditions were assessed at 29 °C ∼ 37 °C and pH 6.1 ∼ 6.9. The observed transformation pathway was HCB → pentachlorobenzene (PCB) → 1,2,3,5-tetrachlorobenzene (TeCB) → 1,3,5-TCB. The dechlorination of HCB was delayed by the addition of ferric chloride and manganese dioxide as electron acceptors, but enhanced by the addition of lactate and pyruvate as electron donors. However, we found that the addition of acetate had no significant effect on HCB dechlorination. Following treatment with bromoethanesulfonic acid (BESA) and vancomycin, it was suggested that the methane-producing bacteria was involved in the dechlorination of CBs.