纳米零价铁灭活二级出水中病原微生物的特性及机理研究

Pathogenic microorganisms in municipal wastewater secondary effluent pose a serious threat to public health, and the secondary effluent can be reclaimed and reused only after disinfection. As a new disinfectant, nanoscale zero-valent iron (nZVI) showes superior performance in inactivation of pathogenic microorganisms due to its excellent surface adsorption and chemical reactivity, and receives wide attention and has been popularly studied. However, the present research usually conducts using prepared water in laboratory, and limited attention has been paid to the water quality especially the effects of various organic matters in secondary effluent. In this study, the systems are built according to the water quality characteristics of municipal wastewater secondary effluent. Considering the hydrophilicity and hydrophobicity of organics, the model organic compounds, the hydrophilic components and hydrophobic components of secondary effluent are used to construct the multicomponent systems. The model microorganisms are used as objects, and the inactivation performance of microorganisms in multicomponent systems by nZVI is studied systematically, especially the effects of dissolved organic matters. Meanwhile, the interactive relationship between nZVI-microorganism-chemicals in complex water is analyzed based on the studies of the energy metabolism and electron transfer process of microorganisms, as well as the interface interaction between species in the systems. The results will provide scientific basis and technical guidance for the application of nZVI to remove pathogenic microorganisms in secondary effluent. It will also lay the foundation for control of pathogenic microorganisms in multi-substance systems such as municipal wastewater secondary effluent.

城市污水二级出水中的病原微生物对人类健康存在潜在威胁，必须经过消毒处理才能再生利用。作为一种新型消毒剂，纳米零价铁因其优良的表面吸附和化学反应活性，对于病原微生物的灭活具有优异的性能，得到了广泛关注和研究。然而，目前的研究一般以实验室配水进行，对实际水质尤其是二级出水中种类繁多的有机物的考虑十分有限。本研究基于城市污水二级出水的水质特征，从有机物的亲/疏水性出发，分别选择模型有机物和实际二级出水的亲/疏水组分构建多组分体系，以模型微生物为对象，系统研究多组分体系中纳米零价铁灭活病原微生物的特性，尤其是溶解性有机物的影响。同时，结合能量代谢和电子传递过程的研究，分析各物种间的界面作用，深入剖析复杂水质中纳米零价铁-微生物-有机物之间的相互作用关系，为将纳米零价铁用于二级出水中病原微生物的灭活提供科学依据和技术指导，为二级出水这种多物质共存体系中的病原微生物的控制奠定基础。

城市污水二级出水中的病原微生物对人类健康存在潜在威胁，必须经过消毒处理才能再生利用。目前关于消毒的研究一般采用模型微生物以实验室配水的方式进行，对实际水质状况的考虑十分有限；模型微生物一般选用与人类肠道病毒性质类似的噬菌体MS2和f2。本研究通过现场调研和监测，分析了城市污水二级出水、再生水及再生水补给型城市景观水体中溶解性有机物的分布及特征，以及再生水补给到城市景观水体后微生物的赋存、传输及归趋特征；在此基础上，以噬菌体MS2、f2、PhiX174以及细菌E.coli作为模型微生物，以腐植酸、海藻酸钠、牛血清白蛋白作为溶解性有机物的代表，从微生物特性和溶解性有机物两个方面研究了多组分体系中纳米零价铁灭活病原微生物的特性，剖析了复杂水质中纳米零价铁-微生物-有机物之间的相互作用关系。研究发现，不同模型微生物对纳米铁的抗性存在较大差异，其中噬菌体PhiX174对纳米铁的抗性远高于MS2，而核酸的破坏是导致噬菌体失活的根本原因；E. coli对纳米铁的抗性也大于噬菌体MS2，MS2的存在加快了E. coli的增殖速度，说明噬菌体的侵染能够刺激宿主细菌调节自身生长规律，E. coli的存在降低了纳米铁对MS2的灭活速率。不同亲疏水性的有机物中，腐植酸和牛血清白蛋白对纳米铁灭活病原微生物主要表现出抑制效应，而海藻酸钠表现出促进作用；三种有机物共存时，腐植酸的抑制作用最明显，而海藻酸钠只有在高浓度时才能促进噬菌体的灭活；实际城市污水二级出水中，纳米铁对噬菌体的灭活受到明显抑制。针对这一结果，课题还探讨了提升纳米铁灭活效率的手段，一方面考察了纳米Fe/Ni双金属灭活噬菌体f2的特性及作用机理，发现纳米Fe/Ni双金属对噬菌体f2的灭活效率明显高于纳米铁，且受pH值影响较小，有氧条件明显优于无氧条件；另一方面针对腐植酸的抑制效应，探讨了光照条件下腐植酸/噬菌体/纳米铁体系中f2的灭活效率，发现光照可以促进腐植酸的光分解和噬菌体的灭活。研究成果可为多物质共存体系中病原微生物的控制提供科学依据和技术指导。