基于硫铁矿自养反硝化的地下水硝酸盐去除机理与工艺研究

The nitrate-contaminated groundwater has represented a potential risk for public health and water security, therefore it becomes a hot research area to select the appropriate electron donors for nitrate biological removal from groundwater. Based on our studies, it was proved that pyrite-based autotrophic denitrification showed high nitrate removal efficiency and low sulfate accumulation. However, the mechanism for pyrite-based autotrophic denitrification is lacked. In this project, by the analysis of the kind and type of the product during denitrification, the transfer and transform of pyrite is illustrated, and the interaction between pyrite and microorganism is explained, so the related denitrification model is built. By use of the clone library, microbial community during denitrification process is analyzed and the relationship between S. denitrificans and T. denitrificans is illustrated. By detecting the gene segment of denitrifying enzyme, the electron transfer mechanism is explained. By means of the calculation of microbial population and the denitrifying gene abundance, the relationship between S. denitrificans and T. denitrificans in the pyrite-based autotrophic and heterotrophic denitrification system is revealed, so the synergistic denitrification process and the related adjustment mechanism are established. With the study of this project, the theoretical foundation for utilization of pyrite-based autotrophic denitrification in nitrate-contaminated groundwater remediation will be established, which will play a positive role in the research for groundwater treatment techniques.

地下水硝酸盐污染威胁居民饮水安全与健康，对电子供体材料的探讨是地下水反硝化领域的研究热点。本课题组已经证明以硫铁矿为电子供体的自养反硝化过程效率高、硫酸盐积累少，但其作用机理尚不明确。本项目通过硫铁矿反硝化过程产物及形态学分析，解析硫铁矿在反硝化过程中的形态转化及微生物与硫铁矿之间的相互作用，建立硫铁矿自养反硝化过程的脱氮模型；利用克隆文库手段分析反硝化系统中微生物菌群结构及变化，解析S. denitrificans与T. denitrificans的相互关系；通过分析反硝化相关酶的编码基因片段，阐明两种细菌在反硝化过程中的电子传递机制；通过分析微生物数量及与反硝化相关的基因片段丰度，阐述硫铁矿自养-异养协同反硝化系统中两种微生物的共存关系，建立硫铁矿自养-异养协同反硝化工艺与调控机制。该研究将为硫铁矿自养反硝化在地下水硝酸盐处理中的应用奠定理论基础，对推动地下水处理工艺研究产生积极作用。

当前，地下水硝酸盐的污染日趋严重，为了满足我国的生活饮用水卫生标准（GB 5749-2006）和世界卫生组织（WHO）制定的饮用水水质准则（第四版），开发出简单、高效、适用性强的含硝酸盐氮地下水的处理技术，具有重大的社会、经济和环境意义。.本项目使用硫铁矿作为自养反硝化的电子供体，从硫铁矿的遴选开始，比较了不同粒径和不同投加量硫铁矿的反硝化性能，并分析了硫铁矿系统的微生物群落结构。此外，为了构建硫铁矿自养反硝化生物反应器，评估了辅助填料（陶粒、白云石、麦饭石和磷矿石）对硫铁矿自养反硝化性能的影响。此外，在硫铁矿自养反硝化性能研究的基础上，将硫铁矿自养和异养反硝化结合，开发了协同反硝化工艺，并比较了不同碳源（葡萄糖、富里酸、锯末）添加下的反硝化性能。.通过上述研究，本项目得出以下重要结果：1、硫铁矿的粒径会显著影响反硝化速率，粒径越小反硝化速率越高；2、硫铁矿的投加量会影响反硝化进行的程度，硫铁矿的最佳投加量为75 g/L；3、硫铁矿自养反硝化系统中起反硝化作用的主要菌种是T. denitrificans和S. denitrificans；4、化学计量关系的氨氮投加量有利于提高硫铁矿自养反硝化的反硝化速率；5、白云石的添加有利于降低出水硫酸盐浓度；6、麦饭石和磷矿石的添加有利于提高硝酸盐氮及总氮去除率； 7、向硫铁矿自养系统中添加葡萄糖可以显著提升硝酸盐的去除率及去除速率；8、向硫铁矿自养系统中添加锯末，构建协同反硝化系统有利于促进硝酸盐的完全还原，并且锯末异养反硝化过程产生的CO2等无机碳源可以满足硫铁矿自养过程所需，并且可以维持pH的稳定；9、在锯末-硫铁矿系统中添加少量的硫磺有利于促进反硝化效率，并且可以提高系统的抗硝酸盐负荷和水力负荷能力；10、在运行初期向锯末-硫铁矿/硫磺系统中补充无机碳源，有利于提高反应器的脱氮性能。