In all known continuous biological processes: (a) only laboratory-scale experiments have been carried out and (b) the pure or mixed bacterial cultures used were immobilized on solid particles.
As shown above, the dechlorination of HCB and PCB is only possible by using anaerobic conditions and auxiliary substrates. Fathepure and Vogel (1991) used a biofilm reactor and were able to transform HCB to 1,2,3,4-TeCB with methanol and to 1,2,3-TCB and 1,2-DCB with acetate as an auxiliary substrate. Nowak (1994) was successful in reducing 1,2,3,4-TeCB, all three TCBs and all three DCBs as well as MCB in a fluidized bed reactor with a mixture of methanol, acetate, acetone, eth-anol, propanol and a mixed culture from a sediment of the Saale River.
Aerobic mineralization of MCB, the three DCBs and 1,2,4-TCB were achieved in fixed bed reactors by Bouwer and McCarthy (1982) with small glass beads for biofilm growth, by Van der Meer et al. (1987) with sand particles from the Rhine River and by Schäfer (1994) with polyurethane foam particles with and without activated carbon as carriers for mixed cultures, or Pseudomonas sp. (Van der Meer et al. 1987). In the experiments by Schäfer (1994), no auxiliary substrates were needed as the source of energy or carbon.
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