废气中H2S与VOCs的生物电强化协同去除及电子转移调控机制

The process of redox reaction is essentially the electron transfer process between the electron donor and the electron acceptor. A large amount of gases containing H2S and volatile organic compounds (VOCs) generate during the processes of sewage and sludge treatment. Both VOCs and H2S are electronic donors, and H2S loses electrons to produce sulfate. Under electric auxiliary conditions, sulfate, the oxidation product of hydrogen sulfide, can be used as an electron acceptor to oxidize VOCs to carbon dioxide, while as sulfate can be reduced to elemental sulfur. A novel technology on synchronous of H2S oxidation, sulfate reduction and VOC oxidation will be investigated during the bioelectrochemical reaction process of odors and VOCs co-treatment in this project. The oxidation products of H2S are utilized to oxidize VOCs to achieve the synergistic transformation of VOCs and H2S, while recovering sulfur resources. Stable and high efficient biological systems of H2S and VOCs synergistic transformation will be set up based on the research of the symbiotic relationship between sulfur-oxidizing bacteria, sulfate-reducing bacteria and VOC oxidation bacteria, as well as the influence of electrode material and current density on their performance. The project tries to construct a novel electrically augmentation bio-system for odors and VOC removal, establish the kinetics model of concerted reaction, determine optimum control conditions and strategies by studying the electrochemical behavior of H2S and VOCs on the surface of the electrode and their synergetic transformation processes, analyzing the variation characteristics in quantity and structures of functional microbial population in biological systems and exploring the mechanism and way of electronic transfer. This will benefit to lay a theoretical foundation for developing novel technology of odors and VOC purification.

氧化还原反应过程实质是电子供体和电子受体之间电子转移过程。污水、污泥的处理过程中，产生大量的H2S及挥发性有机物（VOCs）。VOCs和H2S均是电子供体，H2S失电子产生硫酸盐。电辅助条件下，H2S的氧化产物硫酸盐可作为电子受体，将VOCs氧化为二氧化碳，硫酸盐还原为单质硫。本研究结合H2S氧化、硫酸盐还原、VOCs氧化等生物-电化学反应过程，利用H2S的氧化产物氧化VOCs，实现VOCs和H2S的协同转化的同时，回收硫资源。研究硫氧化菌、硫酸盐还原菌与VOC氧化菌等功能菌的共生关系，构建高效的H2S与VOCs协同转化的生物体系，解析功能菌群落的结构和数量特征，揭示H2S与VOCs在电极界面的电化学行为及其协同转化过程。阐明电子转移机制及途径，建立协同反应动力学模型，确定H2S与VOCs的生物电强化协同去除最佳控制条件与策略，为研究开发同步去除恶臭与VOC的新型生物技术奠定理论基础。

针对污水、污泥处理过程产生的H2S及挥发性有机物，本研究构建高效稳定的H2S-VOCs协同转化电生物体系；考察VOC和H2S去除效果与影响因素，揭示其电极界面的电化学行为，阐明电子转移机制及途径。结果显示，构建的电生物系统不仅可以有效处理难降解VOC，而且有电能产生。H2S的氧化产物主要为硫酸盐。外加电压有助于苯的转化，辅助电压可以改变微生物的膜通透性，有助于VOC被细胞吸收和代谢。 施加电压为1.6V时，苯和甲烷的转化速率最高，达到41.59 mg•L-1•d-1 和 26.61mg•L-1•d-1。反应体系中硫化氢的氧化产物硫酸盐逐渐减少，其转化产物是硫离子和硫单质，电辅助体系硫酸盐生成硫单质的比例更高。Pseudomonas sp.，Stenotrophomonas sp.主导苯及硫的协同转化；Methylocaldum sp.，M. oxyfera参与甲烷厌氧氧化；Desulfovibrio sp., Desulfosporosinus sp. 与硫循环相关的微生物。微生物与电极的电子传递方式包括细胞色素C参与的直接传递以及利用电子穿梭体或腐殖质的间接传递。结合产物种类、产电现象、微生物群落和胞外电子传递功能基因分析，VOC与硫化氢的氧化产物硫酸盐转化的可能途径： VOC被氧化为甲醇等溶解性有机物和二氧化碳，释放电子；硫酸盐还原菌利用VOC氧化释放的电子，将硫酸盐还原为硫离子；脱氮硫杆菌将硫离子转化为硫单质或硫酸盐。将含硫恶臭物质氧化与VOC的生物-电化学转化两个反应过程结合，形成组合式生物-电化学反应器。厌氧氧化VOC无需提供氧气；电极材料及结构有利于电活性微生物附着生长和传递电子。含硫恶臭物质的氧化产物为VOC氧化提供氧化剂，同时，VOC为硫酸盐的还原提供碳源，实现VOC与含硫恶臭物质的协同处理。本项研究为开发同步去除恶臭与VOC新型生物技术奠定理论基础。