固定化混菌联合体同步去除复合污染地下水中硝酸盐和铬(VI)的性能及机理研究

The nitrate and chromium(VI) compound contamination in groundwater has represented a serious threat to water security and public health. Traditional microorganism in situ remediation methods existed lots of problems, such as low microbial density, easy to lose, poor metabolic activity, and difficult to control the denitrification and chromium reduction process. In this project, heterotrophic denitrification and chromium reduction hybrid microbiome were embedded in the polymer structure of the carrier, which can slowly and continuously release microorganisms to simultaneously remove nitrate and chromium (VI). By the analysis of the kind and type of the intermediate products, end products and microbial morphologies during the denitrification and chromium reduction process, the competition and/or cooperation relationship between microbial flora in simultaneous removal of nitrogen and chromium process is illustrated. By detecting the protein components and coding gene fragments of the key denitrifying and chromium reduction enzymes, the electron transfer mechanism is explained and the reaction process mechanism model is constructed. By evaluating the physical and chemical indicators of the bioreactor performance, the related adjustment mechanism of simultaneous removal of nitrate and chromium(VI) from groundwater by an immobilized mixed bacterial consortium is established. With the study of this project, a new approach for treatment of nitrate and chromium(VI) compound pollution in groundwater will be provided. With the study of this project, the theoretical foundation for utilization of an immobilized mixed bacterial consortium in the combined treatment of nitrate and chromium(VI) in groundwater will be established, which will play a positive role in the research for groundwater pollution treatment techniques.

地下水硝酸盐和铬(VI)复合污染严重威胁居民饮水安全和身体健康。传统微生物原位修复方法存在微生物密度低、容易流失、代谢活性差、反硝化和铬还原过程不易受到控制等问题。本项目将异养反硝化及铬还原混合微生物菌群包埋于载体的高分子结构中，使其缓慢连续释放微生物以同步去除硝酸盐和铬(VI)；通过反硝化及铬还原过程中间产物、终产物及微生物形态学分析，解析同步脱氮除铬过程中微生物菌群之间的竞争/协同作用关系；通过反硝化和铬还原关键酶的蛋白组分及编码基因片段分析，阐释微生物同步脱氮除铬过程的电子传递机制，构建反应过程机理模型；以理化指标评估生物反应器同步脱氮除铬运行性能，建立固定化混菌联合体同步去除地下水中硝酸盐和铬(VI)工艺的调控机制。该研究将为固定化混菌联合体在地下水硝酸盐和铬(VI)复合污染处理中的应用奠定理论基础，对推动地下水污染处理工艺研究产生积极作用。

地下水硝酸盐和铬(VI)复合污染严重威胁居民饮水安全和身体健康。传统微生物原位修复方法存在微生物密度低、容易流失、代谢活性差、反硝化和铬还原过程不易受到控制等问题。本项目将异养反硝化及铬还原混合微生物菌群包埋于载体的高分子结构中，使其缓慢连续释放微生物以同步去除硝酸盐和铬(VI)；通过反硝化及铬还原过程中间产物、终产物及微生物形态学分析，解析同步脱氮除铬过程中微生物菌群之间的竞争/协同作用关系；通过反硝化和铬还原关键酶的蛋白组分及编码基因片段分析，阐释微生物同步脱氮除铬过程的电子传递机制，构建反应过程机理模型；以理化指标评估生物反应器同步脱氮除铬运行性能，建立了固定化混菌联合体同步去除地下水中硝酸盐和铬(VI)工艺的调控机制。研究结果发现：（1）硝酸盐的存在有利于微生物还原Cr(VI)过程，且其与硝酸盐浓度成正比，能达到50%最大生物活性的硝酸盐氮浓度为78.22 mg/L；（2）Cr(VI)的存在抑制微生物的反硝化性能，Cr(VI)浓度越高，抑制作用越强，Cr(VI)对微生物活性50%的抑制浓度（IC50）为17.06 mg/L；（3）微生物还原硝酸盐的模型中随机模型最优，而反竞争模型最符合Cr(VI)生物还原，在硝酸盐和Cr(VI)复合降解动力学中表现出典型的非竞争性抑制特性；（4）硝酸盐和Cr(VI)的引入显著降低群落丰富度和多样性，同时富集相应功能微生物，尤其对于Cr(VI)，微生物表现出高度的选择性，反硝化和Cr(VI)还原能量代谢通路和功能基因的富集有利于微生物的脱氮除铬，同时CAT和SOD2等抗氧化基因的富集提高了微生物对Cr(VI)毒性的抵抗能力。该研究将为固定化混菌联合体在地下水硝酸盐和铬(VI)复合污染处理中的应用奠定理论基础，对推动地下水污染处理工艺研究产生积极作用。