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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 ( K B and K C ) under the batch culture and continuous culture were determined to be 1.9 × 10 –2 (mg protein –1 h –1 ) and 1.4 × 10 –2 (mg protein –1 h –1 ), respectively. Maximum specific degradation rate of PCE was calculated as 0.16 (10 –3 μmol mg protein –1 h –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 –1 h –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.

A newly isolated Bacillus subtilis HHT-1 has the ability to oxidize manganese ions. We attempted to immobilize the cells on the microfiltration membrane and remove manganese ions from the raw water as manganese oxides. After subculturing, the broth was filtered with NTF-5200 (pore size 0.2 μm), Nitto, Japan. The filter was set in Nitto Membrane Master RUM-2, Nitto, Japan and used as the bioreactor. Manganese sulfate was dissolved in distilled water to become 1 mg/l or 0.2 mg/l of the final manganese ion concentration, and used as the raw water. The volume of the bioreactor was 10 ml. The flow rate, pressure, retention time of the bioreactor, and circulation frequency were, 0.08 l/min, 0.4 kgf/cm2, 7.5 sec, and 0.04 time/min, respectively. Removal rate of manganese ions rose with increasing cell mass immobilized. The bioreactor was active even at low concentration of initial manganese (0.2 mg/l) and 0.04 mg/l or less of manganese ion concentration in the treated water was obtained.