| Summary: | 碩士 === 東吳大學 === 微生物學系 === 85 === The potential dechlorination of PCBs in medium and anaerobic
digested sludge by a HCB-adapted mixed culture was investigated.
In medium experiment, the results showed the addition of
anaerobic HCB-adapted consortium enhance PCBs dechlorination.
The dechlorination rate of 234-CB, 2345-CB, 23456-CB, 246246-CB,
2345245-CB are 0.17, 0.17, 0.086,0.01, 0.0087 mg/L/day. We also
found optimal conditions for 234-CB and2345-CB dechlorination
rate to be 30 degree, pH 7-8, 10-20% inoculum density. Results
showed, the higher the concentration and number of chlorine, the
longer the dechlorination time. PCBs dechlorination rate
enhanced under methanogenic condition, but inhibited under
denitrifying and sulfidogenic conditions. We found that
dechlorination rates weredelayed by addition of ferric chloride,
manganese dioxide, lactate andpyruvate. However, addition of
acetate had no significant effect on dechlorination. Addition
three kinds of PCBs in mixture and refeeding new PCBs decreased
dechlorination rates, but shaking incubation had nosignificant
effect on dechlorination. Treatment with the microbial
inhibitors, such as BESA, vancomycin and molybdate showed
methanogen was the major population on PCBs dechlori-nation,
sulfate-reducing bacteria and eubacteria involved in dechlorina-
tion. In sludge experiment, we found that dechlorination rates
were significantdifference with various sludge sources, the
higher total solid and number of chlorine, the slower
dechlorination rates. PCBs dechlorinarion had no significant
difference at pH 6-8, but did not dechlorinate at pH 9 during41
days incubation. We found the higher the PCBs concentration, the
higherthe dechlorination rate. Under different conditions,
dechlorination rates were in order of methanogenic conditions
> sulfidogenic conditions > denitrifying conditions. Addition
of acetate, lactate,pyruvate and ferric chloride decreased the
lag phase and enhanced on dechlorination, but it was
inhibited by addition of manganese dioxide. Dechlorination rate
was enhanced by adding three kinds of PCBs in mixture and
refeeding new PCBs.
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