Removal of tetrachloroethylene in an anaerobic fixed-bed reactor immobilized with Clostridium bifermentans DPH-1

Abstract

An upflow fixed-bed reactor was evaluated for the removal of tetrachloroethylene (PCE) by a strictly anaerobic, PCE dechlorinating bacterium, Clostridium bifermentans DPH-1 immobilized on sterile ceramic beads. The ceramic beads provide a large surface area for development of cell mass in the column. For kinetic experiments, the conventional first-order reaction kinetics was applied to evaluate the batch and continuous immobilized reactors. Velocity constants (KB and KC) under the batch culture and continuous culture were determined to be 1.9 × 10–2 (mg protein–1h–1) and 1.4 × 10–2 (mg protein–1h–1), respectively. Maximum specific degradation rate of PCE was calculated as 0.16 (10–3 μmol mg protein–1h–1 from average influent concentration of PCE (12 μM) in the bioreactor. Simultaneously maximum volumetric degradation rate was also computed as 10.2 μmol l–1h–1. The volumetric degradation rate was relatively higher than those of other reactors. In order to maintain the efficiency of PCE dechlorination, 20 h or more HRT in the reactor system was required.