Developmental study on trichloroethylene degradation by a bioreactor

1. 以海藻酸钙固定化Methylocystis sp. M（菌株M）为研究对象，对其液固相降解三氯乙烯（TCE）的性能进行了研究。所得结果如下：(1)为了获得菌株M具有高TCE降解比活性的细胞，培养基中Cu的去除（几乎为零）和在log期结束时收获细胞是非常重要的。(2)确定了固定化细胞降解TCE的动力学常数（vmax和Ks）和最佳条件（pH、温度、DO）。(3)菌株M的降解半衰期较短，这是由于TCE在细胞内降解形成的中间体具有毒性所致。(4)细胞内毒性失活的细胞经甲烷或甲醇孵育后可重新活化，表明固定化细胞可重复用于TCE降解。(5)在最佳条件下，在5L生物反应器中，TCE在120h内半连续降解，总降解量约为13mg。同时研究了固定化电池对TCE气固相降解体系的影响。将0.3ppm的气态TCE连续送入玻璃柱生物反应器，在约50h内几乎完全降解。该反应器可降解的最大TCE浓度为100ppm，说明由于TCE处理设施管道排放的气态TCE浓度过高（300-500ppm），有必要将气态TCE稀释后应用于生物反应器。

1. Characterization of liquid-solid phase trichloroethylene (TCE) degradation by Methylocystis sp. M (strain M) immobilized in Ca alginate was studied to maximize the degradation rate. The results obtained were as follows. (1) In order to get the cells of strain M possessing high specific activity for TCE degradation, elimination of Cu (almost to zero) in the medium and harvesting the cells at the end of the log phase were very important. (2 ) Kinetics constants (V max and Ks) and optimum conditions for TCE degradation (pH, temperature, DO) by immobilized cells were cleared. (3) The half life of the degradability of strain M was relatively short, and which was caused by the toxicity of intermediates formed by TCE degradation in the cells. (4) Inactivated cells by the intracellular toxicity were reactivated by incubation with methane or methanol, suggesting that the immobilized cells was possible to be repeatedly used in the TCE degradation. (5) Under the optimum conditions obtained, semicontinuous TCE degradation in a 5L bioreactor showed that the total amount of approximately 13mg TCE could be degraded in 120h.2. We also studied on the gas-solid phase TCE degradation system by the immobilized cells. The gaseous TCE of 0.3ppm, which was fed continuous into the glass-column bioreactor, was almost completely degraded in about 50h. The maximum TCE concentration to be degraded by this reactor was 100ppm, suggesting that, as the gaseous TCE concentration exhausted from ducts of TCE treatment facilities was too high (300-500ppm), the gaseous TCE was necessary to be diluted and be applied to the bioreactor.