BTEX厌氧降解纯菌株的筛选及降解效率影响因素研究

Study on Screening the Pure Bacteria for BTEX Anaerobic Biodegradation and the Factors Influencing BTEX Biodegradation Efficiency

通过驯化和分离纯化方法,从被污染的土壤中筛选出3株厌氧降解BTEX的纯菌种,对地下水中苯系物(BTEX)在厌氧条件下的微生物降解进行研究。采用正交试验法对BTEX各个组分在不同菌种、不同电子受体和污染物不同起始浓度的条件下生物厌氧降解效率进行研究。结果表明,苯、甲苯和乙苯在以硝酸根和硫酸根为电子受体、污染物初始浓度较低的条件下,降解效率可达95%,而以3价铁为电子受体或者初始浓度较高时降解效率较低。二甲苯在各种条件下都可以得到有效的降解。在各个因素中,电子受体对BTEX降解效率的影响最大。

Three different types of bacteria, which are identified as Bacillus Cereus, Pseudomonas A ureofaciens and Microbacterium Lactuim respectively, were obtained from the BTEX contaminated soil by isolation and purification for several times. A series of three factors-three level orthogonal experiments were performed to investigate anaerobic biodegradation performance of BTEX （benzene, toluene, ethlybenzene and xylenes ）including three types of bacteria;nitrate, sulfate and ferric iron reducing conditions;20 mg·L^-1, 50 mg·L^-1 and 80 mg·L^-1 substrates concentration levels. The results showed that nitrate and sulfate were more favorable electron acceptors compared to ferric iron. The degradation efficieneies of benzene, toluene and ethlybenzene were higher than 95% under nitrate and sulfate reducing conditions compared to 70% under ferric iron reducing condition. Higher substrates concentration led to lower degradation efficiency for the inhibition influence. For Xylenes, the degradation efficiencies keep in a stable high level about 90% hardly influenced by other factors. According to the range analysis of the orthogonal experiment, the electron aeceptor is the most sensitive factor among the three different factors. The sequence of three factors is electron acceptor〉substrate concentration〉types of bacterial.