面向紧凑式高性能微生物燃料电池的耐氧生物阳极构建与调控

Microbial fuel cell (MFC) is a novel technique in wastewater resource, which could recovery energy from wastewater biomass during the treatment process. As the wastewater treatment system, the compact-electrode MFC is considered the ideal configuration, since the close separation distance between anode and cathode help to minimize internal resistance of the reactor. However, oxygen (diffused from the cathode) concentration around the anode increased as electrodes distance reduced, which would inhibit the performance of anode and result in "oxygen contamination". Thus, development of oxygen-tolerant bioanode is required to the compact-electrode MFC system. In this proposal, we will investigate how much and how the oxygen affect the anode biofilm, and then draw up a strategy of regulation and construction of high oxygen-tolerant bioanode based on previous results. The oxygen effect on anode performance will be quantitatively evaluated under different oxygen concentration conditions in both start-up and operating process by electrochemical and biological techniques. The mechanism of the oxygen effect on anode will be studied in biofilm micro-environment by oxygen and pH microsensors, in microbial community by hi-seq technique, in biofilm morphology by scanning electronic microscopy and confocal laser scanning microscopy, and in biofilm metabolic activity by live and dead cell staining. Feedback information will guide the design of oxygen-tolerant bioanode, and thereby improve and optimize the compact-electrode MFC system.

紧凑式微生物燃料电池（MFC）是用于高效废水处理同时回收生物质能的理想构型。但紧凑式MFC存在抑制生物阳极产电能力的"氧气污染"问题。针对这一关键问题，本项目拟采用调控氧浓度研究不同氧浓度对阳极生物膜的成膜过程和产电性能影响，建立阳极生物膜的电化学活性、生物学参数与氧气浓度的关联，调控和构建耐氧生物阳极。利用微探针技术、扫描电镜和激光共聚焦扫描技术查明阳极耐氧生物膜的微环境和微观形态，通过hi-seq技术结合死活菌染色技术从生物膜新陈代谢活性层面和群落结构角度解析氧气对生物膜结构和产电性能影响的机制。为提高紧凑式MFC的性能提供理论和技术支持。

紧凑式微生物燃料电池（MFC）是用于高效废水处理同时回收生物质能的理想构型。但紧凑式MFC存在抑制生物阳极产电能力的“氧气污染”问题。针对这一关键问题，本项目采用调控氧浓度研究不同氧浓度对阳极生物膜的成膜过程和产电性能影响。建立了一套研究氧气对MFC性能影响的氧浓度控制装置，开发出解析阳极生物膜结构组合技术：微生物生长无损观察技术、微电极探测技术和生物膜切片群落分析技术。采用现代电化学分析、原位界面观察和SEM界面微观形貌，建立了阳极生物膜的生长过程并关联了氧气、阳极生物膜结构、电化学性能的系联。得到以下重要发现：（1）氧气对MFC启动过程有重要影响，氧分压越高，MFC启动越慢，但在所研究氧气浓度下（高达20%氧分压）MFC均能启动并达到稳定产电；（2）在无氧条件下形成的阳极生物膜呈单层致密结构，在有氧情况下形成的生物膜呈较厚双层疏松结构；（3）厌氧条件下形成的生物膜和有氧条件下形成生物膜的内层以Geobacter为主，其比例从内向外呈梯度下降分布，而有氧条件下形成生物膜的外层以兼性菌和好氧菌为主，其比例从内向外呈梯度上升分布；（4）外层生物膜消耗氧气保证内层生物膜处于厌氧状态，内层生物膜其产电作用；虽然在好氧启动的阳极生物膜具有一定的耐氧能力，但随着启动阶段氧浓度的增加，阳极生物膜的电化学性能不断下降；（5）小电阻启动的阳极生物膜具有一定的耐氧性，大电阻启动的阳极生物膜不具有耐氧性。小电阻形成的耐氧生物膜呈致密结构，表面微生物被EPS包覆；大电阻形成的不耐氧生物膜呈疏松多孔，表面微生物呈“裸露”状态。解析了高性能耐氧生物阳极的构建与调控机制。（6）提出了致密的阳极生物膜结构是构建高性能耐氧性阳极生物膜和增强阳极生物膜的产电能力的关键。采用小电阻和高剪切力获得了高耐氧能力和产电性能的致密阳极生物膜结构，以耐氧阳极构成的紧凑式MFC的最大产电功率达到4300 mW·m-2。为开发高性能紧凑式微生物燃料电池奠定了基础。