基于微生物燃料电池产电原位利用和电势调控的废水脱氮与硫回收研究

After the organic wastewater containing nitrogenous and sulfurous compounds was anaerobic digested, the electron donor for nitrogen removal from anaerobic digestion effluent was insufficient and the electron acceptor for biogas sweetening was lack. Denitrifying desulfuration Microbial Fuel Cell (MFC) was suitable for simultaneous nitrogen removal from anaerobic digestion effluent and biogas sweetening, while its end products should be controlled in order to completely remove these pollutant and to recover elemental sulfur. The exoelectrogen is proposed to be isolated from denitrifying desulfuration MFC using roll tube dilution method under potentiostatic condition. The microbial characteristics of exoelectrogen would be studied with microcalorimetry and electrochemical analysis. The cooperation of microbiological reaction and spontaneous electrochemical reaction would be studied through electron exchange analysis and chronoamperometry analysis. The response of electrode reaction pathway to potential driving is proposed to be explored with intermediate product test and potentiostatic test. The electrode biochemical reaction pathway, driven interactively by two electrode potentials, would be interpreted from the point of biothermodynamical view using microcalorimetry and electrochemical analysis. After the mechanisms of denitrification and desulfuration driven interactively by two electrode potentials in MFC are revealed based on above research, the parameter for complete pollutant removal and elemental sulfur recovery would be brought forward. Then the strategy for nitrogen removal from wastewater and elemental sulfur recovery based on in-situ utilization of generated electricity and potential control would be explored. The results would be of great significance for treatment of wastewater containing nitrogenous and sulfurous compounds and recovery of sulfur resource as well. Also it would develop a route for study of electrode reaction mechanism and control of end product in MFC.

含氮硫有机废水厌氧处理后，消化液脱氮的电子供体不足，沼气脱硫则缺乏电子受体。反硝化脱硫微生物燃料电池（MFC）可同步完成消化液脱氮和沼气脱硫，但需控制产物形式，以彻底去除氮硫污染并回收单质硫。本项目拟采用基于恒电位的稀释摇管法从反硝化脱硫MFC中分离产电菌，微量热和电化学分析研究产电菌的微生物特性。电子交换量法和计时电流法分析微生物反应与自发电化学反应的协作，中间产物添加试验和恒电位试验研究电极反应途径对电势驱动的响应，微量热和电化学分析从生物热力学的角度解析两极电势交互驱动下的电极生化反应途径。综合微生物、电化学与生物热力学研究，揭示MFC两极电势交互驱动下的反硝化脱硫机理，获得彻底去除污染物和回收单质硫的条件。在此基础上，探讨基于MFC产电原位利用和电势调控的废水脱氮与单质硫回收策略。研究结果对氮硫废水治理和硫回收具有重要意义，也为MFC电极反应机理研究和产物控制提供思路。

反硝化脱硫微生物燃料电池（MFC）可同步完成废水脱氮脱硫，但需控制产物形式。本项目采用多种MFC构型同时去除废水中的碳氮硫并回收电能。通过恒电位试验、电化学分析、微生物群落分析和微量热分析等手段研究MFC两极电势交互驱动下的反硝化脱硫机理，获得污染物去除和产物控制的条件。研究了产电原位利用和电势调控下MFC的污染物去除性能和产物形式。主要研究结果如下：.1）基于反硝化脱硫MFC开发的三室型MFC、耦合MFC系统和环状MFC系统是同步去除废水中碳氮硫并回收电能的有效方法。在最优条件下，环状MFC系统对TOC和硫化物的去除率均为100%，总氮去除率为82.6±0.9%，单质硫生成率为35.1±4.4%，库仑效率为53.0±2.2%。.2）基于恒电位的稀释倍数法可用于分离电活性菌。反硝化阴极中的硝氮还原过程为直接电子传递模式，亚硝氮还原过程为间接电子传递模式。微量热分析表明，反硝化电活性菌在阴极电势为-150mV时的比代谢速率达到最大值（3.30±0.22）×10-10mgNO3--N（min·个），相应的生长速率常数为（4.20±0.51）×10-3/min。.3）反硝化脱硫MFC的污染物去除性能和产物形式受两极电势的交互影响。改变外阻可调节阴极电势，阴极电势为−139±37mV时取得最佳的单质硫生成率（32.4±1.9%）和气态氮生成率（92.5±0.3%）。.4）交替充放电运行模式可实现反硝化脱硫MFC的产电原位利用。充放电时间、外阻分配、进水浓度和温度影响MFC两极电势范围，进而影响污染物去除与产物形式。30℃有利于硝氮去除和气态氮生成，总氮去除负荷为16.5±0.8gN/(m3·d)，气态氮生成率为32.2±1.5％。40℃有利于单质硫生成，单质硫生成率为48.8±0.2％。.本研究为含氮硫废水治理和硫回收奠定了理论基础，也为MFC反应机理研究和产物控制提供借鉴。