光照调控微藻产氧抑制微生物电解电池制氢中产甲烷过程与机制

Microbial electrolysis cell (MEC) can utilizes almost all biodegradable biomasses including wastewaters to produce hydrogen with high efficiency, and is considered as one of most potential way for future sustainable biohydrogen production. However, the significant amount of methane was generated through the hydrogen-consume or direct electrochemical way of methanogenesis with fast growth of methanogenus during MEC operation, resulting in a low hydrogen production rate of MEC. How to efficiently inhibit methane production is the key problem for MEC hydrogen production. In this project, a new system of microalgae-introduced MEC is set up by introducing microalgae into MEC system for efficiently inhibiting methane production by in-situ produced oxygen from microalgae growth, based on the fact that in the oxygen- contained environment the methanogenus can not grow while the electroactive bacteria can works well. The process and mechanism of methane inhibition by in-situ produced oxygen from microalgae growth, the coexistence and interaction between the electroactive bacteria and microalgae are studied. By controlling illumination conditions, pH and temperature, the effects of oxygen produced on the activity and hydrogen production efficiency of electroactive bacteria are investigated. The oxygen consumption process and its effect on the coexistence of bacteria and microalgae are also studied for developing the MEC hydrogen production with long-term stability and high efficiency.

微生物电解电池(MEC）可利用任何生物可降解的物质包括各种有机废水来高效制备氢气,被认为是未来可持续生物制氢最具潜力的方法之一。但由于MEC中的富氢环境，产甲烷菌快速生长消耗氢气或直接电化学产甲烷,导致氢气产率显著下降。如何抑制MEC中产甲烷过程是MEC制氢技术的关键问题。本项目基于产电菌和产甲烷菌对氧气耐受能力的差异，提出利用微藻现场产生氧气实现在不影响产电菌活性的情况下完全长期抑制产甲烷菌生长的途径。拟构建微藻-微生物电解电池制氢系统，通过改变光照、溶液pH和温度等条件控制微藻的生长速度，探讨微藻产氧对产电微生物的活性和产氢效率的影响；研究系统中氧气消耗的过程和对微藻-细菌共存体系的影响，研究微藻和产电微生物之间可能的相互影响；查明微藻生长现场产氧有效抑制产甲烷菌生长的过程和机制，实现MEC长期稳定和高效产氢。

微生物电解电池(MEC）是未来可持续生物制氢最具潜力的方法之一。但由于MEC中的富氢环境，产甲烷菌快速生长消耗氢气或直接电化学产甲烷,导致氢气产率显著下降，制约这一技术的快速发展。针对这一关键问题，本项目提出利用微藻现场产生氧气实现在不影响产电菌活性的情况下完全长期抑制产甲烷菌生长的途径。构建了微藻-微生物电解电池制氢系统，通过改变光照、溶液pH和温度等条件控制微藻的生长速度，探讨了微藻产氧对产电微生物的活性和产氢效率的影响；研究了系统中氧气消耗的过程和对微藻-细菌共存体系的影响；查明微藻生长现场产氧有效抑制产甲烷菌生长的过程和机制，得到了以下重要发现：（1）在接种产电细菌和微藻启动MEC过程中，MEC阳极微生物均能生长成膜，表明MEC系统中微藻和阳极产电菌能共存；（2）在光强2000-8000lx范围内，微藻产氧随光强增加而线性上升；随藻液细胞浓度增加而增加，当藻液光密度高于0.8时，微藻产氧速率趋于稳定值；温度对微藻产氧的影响不大；微藻产氧量随pH值增加呈现先增加后降低，在pH值为7.0左右时达到最高；在优化条件下，微藻-MEC耦合系统的产甲烷率可稳定控制在10%以内，而未添加微藻的MEC反应器其甲烷产生率达到80%。（3）微藻在有基质存在下发生有氧呼吸消耗溶液中氧气，当不含和含低浓度基质时，微藻产氧能使溶液中的溶解氧达到稳定值。但基质浓度较高时，微藻有氧呼吸占主导，溶液中氧气浓度逐渐降低为零；（4）对稳定的微藻-MEC系统，光照时长小于12小时时，微藻在3000lx-9000lx光强下产生的溶解氧量对MEC阳极性能无明显影响；（5）光照强度主要影响产甲烷菌菌群，对产电菌菌群影响小；（6）外加电能方式影响MEC产甲烷菌的生长和稳定性；光照促进物质传输，提高基质利用效率。研究结果具有指导微藻产氧抑制甲烷菌生长，微藻-产电菌共存研究的科学意义，为开发高性能MEC奠定基础