Lyew D, Guiot S
Biotechnology Research Institute, National Research Council Canada, 6100 Royalmount Avenue, H4P 2R2, Montreal, Quebec, Canada.
Appl Microbiol Biotechnol. 2003 May;61(3):206-13. doi: 10.1007/s00253-003-1224-8. Epub 2003 Feb 27.
The effects of four aeration and four organic loading (OLR) rates on trichloroethylene (TCE) degradation in methanogenic-methanotrophic coupled reactors were studied using ethanol as the carbon source for the methanogens. Microcosm and PCR studies demonstrated that methanotrophs capable of mineralizing TCE and methanogens were present in the biomass throughout the study. The gene for the particulate form of methane monooxygenase (pMMO) was detected by PCR, but not that for the soluble form (sMMO). TCE mineralization by methanotrophs was therefore due primarily to pMMO activity. Low TCE concentrations were measured in effluent and off-gas samples in all cases. Volatilization losses were 0-5%. Dichloroethylene (DCE) was also observed, but vinyl chloride and ethylene were never detected. Changes in the aeration rate had no effect on TCE removal, but did influence DCE degradation. Reductive dechlorination of TCE to DCE was favored at low and no-aeration conditions, and DCE accumulation occurred due to slow DCE degradation. Low DCE levels were observed at the higher aeration rates, which indicated that conditions in these reactors were amenable to the aerobic co-metabolism of TCE and DCE. The OLR did have an effect on TCE removal. TCE and DCE removal were negatively affected when the OLR was increased. An OLR of 0.3 g COD l(rx)(-1)day(-1) or lower with an aeration rate of 3 l(O2 )l(rx)(-1)day(-1) and higher is the recommended operating condition of a coupled reactor for removal of TCE.
以乙醇作为产甲烷菌的碳源，研究了四种曝气速率和四种有机负荷率对产甲烷-甲烷氧化耦合反应器中三氯乙烯（TCE）降解的影响。微观世界和聚合酶链反应（PCR）研究表明，在整个研究过程中，生物质中存在能够使TCE矿化的甲烷氧化菌和产甲烷菌。通过PCR检测到了颗粒形式的甲烷单加氧酶（pMMO）基因，但未检测到可溶性形式（sMMO）的基因。因此，甲烷氧化菌对TCE的矿化主要归因于pMMO活性。在所有情况下，流出物和废气样品中的TCE浓度均较低。挥发损失为0-5%。还观察到了二氯乙烯（DCE），但从未检测到氯乙烯和乙烯。曝气速率的变化对TCE去除没有影响，但确实影响了DCE的降解。在低曝气和无曝气条件下，TCE还原脱氯生成DCE的反应更有利，由于DCE降解缓慢，导致DCE积累。在较高曝气速率下观察到低DCE水平，这表明这些反应器中的条件有利于TCE和DCE的好氧共代谢。有机负荷率确实对TCE去除有影响。当有机负荷率增加时，TCE和DCE的去除受到负面影响。对于去除TCE的耦合反应器，推荐的操作条件是有机负荷率为0.3 g COD l(rx)(-1)day(-1)或更低，曝气速率为3 l(O2 )l(rx)(-1)day(-1)及更高。
