共存氯苯类同系物对六氯苯厌氧降解活性的影响

微生物厌氧降解六氯苯已经成为国内外六氯苯污染土壤修复技术研发的前沿和热点.研究了在不同的初始pH值、反应温度及固液比等环境条件下,3种共存氯苯类同系物五氯苯、1,2,4,5-四氯苯、1,2,4-三氯苯对染料厂污染土壤中六氯苯厌氧降解活性的影响.结果表明,在降解过程中,共存氯苯类同系物的累积对六氯苯的厌氧降解产生了反馈抑制作用,影响了六氯苯的降解活性,且在不同的环境条件下,累积规律不同,反馈抑制作用不同.反应的初始pH值较低时,五氯苯的的反馈抑制作用更突出,反应的初始pH值较高时,1,2,4-三氯苯的反馈抑制作用更突出;常温下,五氯苯的反馈抑制作用更突出,较高温度下,1,2,4-三氯苯的反馈抑制作用更突出;固液比越小,五氯苯的反馈抑制作用越突出.因此,针对性地采取提高低氯苯类同系物降解活性的措施,降低共存低氯苯类同系物在六氯苯厌氧降解过程中的累积,不失为提高污染土壤中六氯苯降解率的一种好的选择.

Effect of the Coexistence of Chlorobenzene Homologue on Anaerobic Degradation of Hexachlorobenzene

The anaerobic biodegradation of hexachlorobenzene is being an intensively studied technology for contaminated soil remediation. The effect of three coexisting chlorobenzene homologue (pentachlorobenzene, 1,2,4,5-tetrachlorobenzene and 1,2,4-trichlorobenzene) on anaerobic degradation of hexachlorobenzene in dye processing industry contaminated soil was studied under different environmental conditions such as initial pH, reaction temperature and solid-liquid ratio. The result showed that the anaerobic degradation activity of hexachlorobenzene was reduced due to the feedback inhibition caused by accumulation of chlorobenzene homologue. The feedback inhibition and accumulation may vary based on different environmental conditions. Pentachlorobenzene exhibited the strongest inhibitive effect compared to the other two chlorobenzene homologue with low initial pH values, at room temperature and low solid-liquid ratio, respectively. Whereas 1,2,4-trichlorobenzene significantly inhibited the degradation with high initial pH values and at higher temperature. As a conclusion, optimization of environmental conditions and reduction of chlorobenzene homologue accumulation in the process can enhance the degradation of hexachorobenzene in contaminated soil.