负压单室MEC中产甲烷抑制效应及其调控机理

Methanogenesis is a key factor of limiting the hydrogen yield in a single-chamber MEC. Our previous study found that the methanogenic process was significantly inhibited. Moreover, we demonstrated that a higher hydrogen yield was obtained in a single-chamber MEC under active vacuum control while treating with the volatile fatty acids (VFAs). However, the specific regulation mechanism of methanogenic inhibition is not clear in this system. This study mainly focus on two unique system environmental factors: vacuum degree and electric field. Firstly, the quantitative effect of vacuum degree and electric field on methanogenic inhibitory action will be explored by using laboratory simulation and dynamic analysis, aiming at clarify the response law of vacuum degree /electric field-VFA-methanogenic inhibitory effect; Secondly, the microbiological methanogenic pathway and its coupling influencing mechanism of vacuum degree and electric field will be determined by isotopic tracer, high-throughput sequencing etc., revealing the interactions relationship among methanogenesis, VFA and environmental factors; Finally, substrate mass transfer model, quantitative PCR, etc. will be used to ascertain the coupling relationship among vacuum degree, electric field and substrate mass transfer - key microbial community structure - key enzyme activity, which clarified the regulation mechanism of the methanogenic inhibitory effect from the substrate mass transfer coupled with the microbiological ecology. Accordingly, the control strategy of a single-chamber MEC for inhibiting methanogenesis is proposed. Results of this study will provide the basis and reference for the theoretical research and technical development of hydrogen clean energy preparing based on carboxylate platform.

产甲烷是单室MEC中制约氢气产率的关键因素。实验室前期研究发现，负压控制的单室MEC处理挥发性脂肪酸(VFA)时产甲烷过程被明显抑制，进而获得了较高的氢气产率。但是该体系中产甲烷抑制的具体机理并不清楚。本项目紧扣体系特有的负压和电场环境因素，首先通过实验模拟和动力学分析，定量表征负压和电场调控产甲烷抑制效应的影响，以明晰负压/电场-VFA-产甲烷抑制的响应规律；其次，利用同位素示踪，高通量测序等解析负压和电场耦合作用下的微生物产甲烷路径及其影响机制，揭示其与VFA、环境因素间的交互作用；最终采用底物传质模型构建、定量PCR等，探明负压和电场与底物传质-关键微生物群落结构-关键酶活间的耦联关系，进而从底物传质耦合微生物生理生态层面来阐明负压和电场对产甲烷抑制效应的调控机理，并据此提出单室MEC抑制产甲烷的调控策略，从而为基于羧酸盐平台的氢能源制备的理论研究和技术开发提供重要依据和参考。

微生物制氢可以获得有机废物降解和氢能回收的双赢，对解决日益严峻的能源危机、全球变暖及环境污染影响等具有重要的战略意义，已成为研究热点。利用单室微生物电解池（MEC）可以实现电化学耦合微生物制氢，但仍存在突出的产甲烷消耗瓶颈。因此，抑制产甲烷是单室MEC中提高氢气产率的关键。本研究以负压控制为突破点，紧扣单室MEC体系中功能微生物与电场-负压的交互作用，明确了负压和电场与挥发性脂肪酸（VFA）产甲烷抑制效应间的定量关系，确定了最佳的负压和电场条件；进一步地，通过微生物生理生态行为机制和物质代谢规律分析，探明了负压MEC中产甲烷抑制效应的影响机制，即Geobacter等VFA消耗类电化学微生物的群落竞争优势、负压形成的低氢气含量的底物受限压力分别有效抑制了乙酸营养型和氢营养型产甲烷途径，进而提高了体系的产氢效率；在此基础上，结合底物传质规律和种间电子传递机制研究，揭示了电场和负压胁迫下体系中产甲烷抑制效应的调控机理，并建立了抑制VFA产甲烷强化产氢的可行性策略，包括开发污泥热解气修饰钛的生物阳极、暗发酵-负压MEC耦合工艺，并采用实际样品进行了验证，从而为丰富和推广羧酸盐平台的氢能源制备技术提供重要依据和理论参考。