Enhanced dechlorination of aroclor 1242 in an anaerobic continuous bioreactor

Disappearance of Aroclor 1242 was observed in a continuously operated upflow anaerobic sludge bed (UASB) reactor inoculated with granular anaerobic sludge. To distinguish between sorption and dechlorination processes, extraction of Aroclor from the sludge was performed along with the measurements of chloride and Aroclor in the reactor effluent. A release of inorganic chloride combined with the enrichment in lightly chlorinated congeners was observed. Based on the chloride balance, the dechlorination process was found to be Aroclor concentration-limited at an Aroclor load of 0.4 mg/(g VSS day) due to a low solubility of Aroclor in water. While an addition of Tween 80 to the influent stream improved solubility of Aroclor, it led to self-inhibition of the dechlorination process at a load of 1.3 mg/(g VSS day). The maximal dechlorination rate observed in this study was 0.6 mg Aroclor/(g VSS day).