Abstract:

This study focused on the issue of low CO₂ reduction rate on the biocathode in microbial electrolysis cells (MECs). By changing the flow field environment of cathode chamber, the effect of flow field on the start-up, operation, products transformation and functional microorganism on the biocathode were explored. Furthermore, the response of CO₂-reduction biocathode performance of MEC to flow field was clarified. The results showed that the flow field enhanced the ability of CO₂-reduction of biocathode (electronic consumption increased by 10%, of which CO₂ to acetic acid pathway consumption increased by 30%), and changed the CO₂ reduction pathway of biocathode (from methane production in the start-up stage to acetic acid production in the operation stage). The high-throughput analysis showed that the flow field changed the microbial community structure of the biocathode and catholyte, making the biocathode dominated by the hydrogenotrophic methanogens (Methanobacterium) to that by the acetoclastic methanogens (Methanosaeta).The abundance of acetogenic bacterial communities (Petrimonas, Candidatus_Caldatribacterium) increased by 3.8% compared with the control group, which played an important role in the process of CO₂-reductionforacetic acid production. This research aims to provide theoretical and technical support for the directed regulation of MEC reduction of CO₂ to produce acetic acid.

Key words: microbial electrolysis cell (MEC), biocathode, CO₂ reduction, flow field, microbial community structure

摘要：

针对微生物电解池 （microbial electrolysis cell，MEC）CO₂还原过程阴极CO₂还原速率低的问题，本文通过改变阴极室的流场环境，探究流场对生物阴极启动、运行、产物及功能微生物的影响，阐明MEC生物阴极CO₂还原性能、产物转化、微生物群落对流场的响应关系。结果表明，流场不仅增强了生物阴极还原CO₂能力（电子消耗量提高了10%，其中CO₂产乙酸途径消耗电子量提高了30%），还使生物阴极的CO₂还原途径由启动阶段的CO₂还原产甲烷转变为运行阶段产乙酸。高通量分析表明，流场改变了生物阴极和阴极液的微生物群落结构，使阴极生物膜的嗜氢型产甲烷菌（Methanobacterium）向嗜乙酸型产甲烷菌（Methanosaeta）主导的群落演变。产乙酸菌群落（Petrimonas、Candidatus_Caldatribacterium）丰度较对照组提高了3.8%，在CO₂产乙酸过程中起到重要作用。本研究可为MEC还原CO₂产乙酸的定向调控研究提供理论和技术支撑。

关键词: 微生物电解池, 生物阴极, CO₂还原, 流场, 微生物群落