利用共代谢机制去除地下水二噁烷与氯代烃混合污染羽

1,4-Dioxane has been used as a stabilizing agent in chlorinated solvents and it has recently emerged as a groundwater contaminant. Consequently, dioxane is typically found as an environmental contaminant in conjunction with groundwater chlorinated solvent plumes. In the last several years, the aerobic biodegradation of dioxane or chlorinated solvents has been demonstrated in laboratory studies, but the simultaneous biodegradation of dioxane and chlorinated solvent co-contaminants have not yet been investigated. The overall objective of this project is to evaluate the BTEX as stimulants for the aerobic cometabolism of dioxane and its co-contaminants, including trichloroethene (TCE), and 1,1,1-trichloroethane (TCA). The effects of three of the most common dioxane con-contaminants, TCE, and TCA, on dioxane biodegradation kinetics during co-metabolic degradation will be evaluated, and the interactions between hydrocarbon growth substrates (BTEX), dioxane, TCE, and TCA will also be evaluated. The major products of dioxane degradation by these organisms will also be determined using HPLC/MS and HPLC-LSC, and a Monod kinetic model will be developed to describe the influence of the major intermediates toward dioxane degradation. The enzymes participated in metabolism of pollutants can be identified by 2-DE and MALD-TOF-MS, which will be used to confirm the biochemical pathway of dioxane. Differential protein expression of degradation strain stressed by pollutants will also be analyzed by 2-DE, which will be helpful to our deep understanding of the biodegradation. This project will provide a thorough evaluation of the potential use of BTEX mixture as selective stimulants for the in situ cometabolic degradation of dioxane and its associated contaminants. These studies can be used to develop predictable, reliable, and cost-effective biotreatment processes for mixture of dioxane, chlorinated solvents, and BTEX in groundwater.

三氯乙烯和三氯乙烷是广泛应用的工业溶剂，而二噁烷在氯代烃溶剂生产中用作稳定剂，这些工业溶剂的广泛使用带来了较为突出的地下水污染问题。如何去除地下水中氯代烃和二噁烷已成为近年来的一个研究热点，然而还没有关于同时去除氯代烃与共存污染物二噁烷复合污染方面的研究报道。本申请通过富集、分离等方法筛选能以单环芳烃为生长基质共代谢二噁烷与氯代烃溶剂的菌株，实现混合污染羽的同时降解。阐释共存有机污染物的交互作用机制及动力学过程；利用同位素示踪结合HPLC-MS技术鉴定代谢产物，推测二噁烷的代谢途径；通过对压力胁迫下降解菌蛋白质组学分析，识别参与代谢的关键酶，进一步确证二噁烷的代谢途径，并分析微生物在复合污染胁迫下的应答机制以及适应性反应，从而为生物修复现实地下水中最常检出的二噁烷、三氯乙烯、三氯乙烷与单环芳烃的混合污染羽提供理论基础和和技术指导。

三氯乙烯和三氯乙烷是优良的工业溶剂，被广泛用作脱脂剂、清洗剂等，而二噁烷在氯代烃生产中用作稳定剂。氯代烃溶剂的广泛使用带来了较为突出的地下水污染问题。鉴于二噁烷、氯代烃和BTEX是地下水中最常见的有机污染物，并且往往同时存在于环境中，对人类的健康已造成很大的威胁。目前国内外尚缺乏有效可行的处理上述地下水中混合污染羽的措施。因此探索高效的去除地下水氯代烃、二噁烷、BTEX复合污染的方法具有重要的现实意义。本研究分离的假单胞菌Pseudomonas plecoglossicida能够实现多种复合污染物的同时降解，并阐释共存有机污染物的交互作用、分析潜在降解机制；结合主成分分析、聚类热图等多元统计分析手段优化了复合污染物生物降解的环境条件，包括湿度、温度、pH、生长基质/非生长基质比。同时利用废旧轮胎作为微生物固定化载体材料增强修复混合污染羽。此外，通过设置长期的污染物胁迫[T1: 二噁烷、T2: BTEX、T3: 二噁烷+BTEX、T4: 二噁烷+TCE+TCA、T5: BTEX+TCE+TCA、T6: 二噁烷+ BTEX+TCE+TCA]，结合其群落结构多样性及功能基因丰度，以期解析微生物降解菌群在污染胁迫下的应答机制以及适应性反应。从而为好养生物修复现实地下水中最常检出的二噁烷、三氯乙烯、三氯乙烷与单环芳烃的混合污染羽提供理论基础和和技术指导。