結合微生物脫氯作用與化學氧化反應進行含氯芳香族化合物之降解研究

Degradation of Pentachlorophenol and Hexachlorobenzene in a Sequence of Microbial Dechlorination and Chemical Oxidation

結合化學氧化與生物分解程序進行有機毒性物質之排除，為近來頗受重視之研究方向，本研究主軸在於探討生物脫氯作用與化學氧化反應之結合成效，並進行五氯酚與六氯苯之生物脫氯降解與化學氧化程序之接續性分解實驗。研究成果顯示，僅採用化學氧化降解，高含氯量之芳香族化合物確實具有抵抗化學氧化之特性，因此Fenton系統針對這類化合物並無明顯降解效果。反之，微生物脫氯降解方面，脫氯作用進行之難易與否與含氯量多寡並無明顯關係，以氯苯化合物而言，高含氯量之六氯苯、五氯苯反較二氯苯更易進行脫氯作用。至於以Fenton系統處理六氯苯與五氯酚之脫氯產物－－1,3,5-三氯苯、1,3-二氯苯、1,4-二氯苯、3,4,5-三氯酚、3,5-二氯酚，其降解率可達72%、88%、86%、68%與85%。然而若將化學與脫氯兩步驟結合，因為脫氯作用溶液之有機質與微生物的干擾，其後續之化學氧化效率會明顯降低，因此本研究亦採用不同處理方式以減少脫氯溶液之有機質成分與含量，實驗結果發現，當反應溶液之有機質減低時，脫氯產物之後續氧化降解作用有明顯提高之現象，顯示厭氧脫氯作用後，低有機質之培養液有利於後續氧化作用進行，此外，適當降低有機質之方法亦有助於氯酚與氯苯化合物之氧化效率。

Recently, a combined method of chemical oxidation treatment and biological degradation treatment to deplete the pentachlorophenol （PCP） and hexachlorobenzene （HCB） pollutants was discussed. In this study, the degradations of PCP and HCB were made by microbial dechlorination coupling with chemical oxidation procedures. The results suggested that the highly chlorinated aromatics were more resisted to Fenton oxidation than less chlorinated ones. On the other hand, highly chlorinated aromatics were strongly dechlorinated by acclimated microorganisms but less chlorinated ones were not. In the oxidation experiment of the dechlorination products of HCB and PCP, 135-trichlorobenzene （135-TCB）, 13-dichlorobenzene （13-DCB）, 14-DCB, 345-trichlorophenol （345-TCP）, and 35-dichlorophenol （35-DCP） were treated by Fenton system with decomposition ratios of 72%, 88%, 86%, 69% and 85%, respectively. However, when HCB and PCP were first dechlorinated by acclimated anaerobic microorganisms for removal of chlorines and then introduced directly to a Fenton system for following oxidation and ring cleavage. The organic matters in the dechlorination solutions had reduced the extent of oxidation. In this study, we also evaluated how the organic contents affected the efficiency of Fenton system.