Abstract:

The use of microbial electrolysis cells (MEC) technology, in conjunction with the cooperative action of electroactive microorganisms on the anode, achieves the removal of sulfides. This is a new process for biogas desulfurization and a research hotspot. For long-term operation of the desulfurization MEC process, non-specific cation competition causes proton transfer from the anode to the cathode to be impeded, resulting in low desulfurization efficiency and unstable operation. In this study, different initial pH values were used to regulate the proton balance in the desulfurization MEC. Through analysis of desulfurization performance, electrochemical performance, and microbial kinetics, the influence of pH regulation on the desulfurization performance of the MEC and the microbial mechanism were elucidated. The findings demonstrated that highly effective and stable anode biofilms capable of removing sulfides could be established at initial pH between 7 and 9, with comparable maximum current densities, sulfide removal efficiencies exceeding 95%, and COD removal rates over 80%. In comparison to initial pH of 8 and 9, pH fluctuation during the desulfurization process was minimized at an initial pH of 7, contributing to greater MEC stability and S^2- removal rates reaching up to 100%. The oxidation-reduction peak of the anode biofilm was pronounced, with accelerated proton and electron transfer rates. Thiomonas and Desulfovibrio microorganisms were dominant, exhibiting higher abundance and primarily involved in the oxidation removal of sulfides. These results underscored the importance of regulating the initial pH of the MEC anode chamber to improve MEC desulfurization efficiency and operational stability while providing valuable technical support for microbial electrochemical biogas desulfurization applications.

Key words: microbial electrolysis cells (MEC), desulfurization, initial pH, mass transfer, biofilm

摘要：

采用微生物电解池（MEC）工艺，在阳极电活性微生物的协同作用下实现硫化物的脱除，是沼气脱硫新工艺和研究热点。针对长期运行的脱硫MEC工艺，由于非特异性阳离子竞争使阳极产生的质子向阴极转移受阻，造成MEC脱硫效率低、稳定运行难，本研究采用不同初始pH调控脱硫MEC的质子平衡，通过脱硫性能、电化学性能和微生物动力学解析，阐明pH调控对MEC脱硫性能的影响和微生物作用机制。结果表明，初始pH在7~9时均可形成稳定且具有高效脱硫功能的阳极生物膜，最大电流密度相近，脱硫效率均达95%以上，COD去除率80%以上。与初始pH为8、9相比，初始pH为7时，脱硫过程pH波动最小，MEC运行稳定，S^2-去除最高达100%；阳极生物膜的氧化还原峰最显著，质子与电子转移速率加快；优势微生物Thiomonas与Desulfovibrio丰度更高，主要参与硫化物的氧化脱除。可见，通过脱硫MEC阳极室初始pH的调控，可有效提高MEC脱硫工艺性能和运行稳定性，为沼气微生物电化学脱硫的应用提供技术支撑。

关键词: 微生物电解池, 脱硫, 初始pH, 传质, 生物膜