Developmental study on trichloroethylene degradation by a bioreactor

1.甲基胞囊藻液-固相降解三氯乙烯的特性研究了海藻酸钙固定化M(菌株M)的降解率。获得的结果如下。(1)为了获得对TCE具有较高比活性的菌株M，去除培养液中的铜(几乎为零)和在对数生长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)和最佳降解条件(pH、温度、DO)。(3)菌株M的降解半衰期较短，这是由于TCE降解中间产物对细胞的毒性所致。(4)细胞内毒性失活的细胞经甲烷或甲醇孵育后可重新激活，表明固定化细胞可重复用于TCE的降解。(5)在优化条件下，在5L生物反应器中进行了TCE的半连续降解试验，结果表明，120h内可降解约13mgTCE。并利用固定化细胞对气固相TCE降解体系进行了研究。连续进料到玻璃柱生物反应器中的0.3ppm的气态三氯乙烯在50h左右几乎完全降解。该反应器可降解TCE的最大浓度为100ppm，说明由于TCE处理设施管道排出的气态TCE浓度过高(300-500ppm)，需要对气态TCE进行稀释并应用于生物反应器。

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.