污泥炭强化微生物电解池提高污泥厌氧消化甲烷产率与系统稳定性

投加污泥炭可有效改善利用微生物电解池厌氧消化(MEC-AD)甲烷产率偏低的问题，但其对MEC-AD体系的长期影响仍未知。研究了不同运行条件(外加电压、有机负荷率OLR)下，污泥炭对MEC-AD在连续进料运行模式下产甲烷效能的提高。首先，基于甲烷产率、电流密度等指标，确定最佳外加电压为1.5 V；然后，在相同外加电压(1.5 V)、不同OLR的条件下，比较了对照组(ME1.5)和投加污泥炭的实验组(MEBC1.5)的产甲烷和系统稳定性，OLR通过水力停留时间(HRT)控制。结果表明，当HRT从10 d逐步缩短至2.5 d，ME1.5与MEBC1.5的甲烷产率呈现先上升后下降的变化趋势，且MEBC1.5的甲烷产率始终高于ME1.5。这表明污泥炭在不同OLR运行条件下均可改善甲烷产率。微生物群落多样性分析结果表明，对比ME1.5与MEBC1.5，投加污泥炭使得生物阴极优势菌属Coprothermobacter、Fervidobacterium、Bellilinea、Methanosarcina的相对丰度分别增加了34.1%、186.6%、130.5%、9.5%。KEGG通路分析结果表明，MEBC1.5中乙酸裂解途径和H₂还原CO₂途径产甲烷代谢过程相关基因的丰度均有所提高。本研究结果可为污泥炭强化市政污泥MEC-AD产甲烷效能和相关的微生物机制提供参考。

Sludge-derived biochar enhanced microbial electrolysis cell for improving biomethane productivity and system stability in anaerobic digestion of waste activated sludge

Adding sludge-derived biochar has been demonstrated to improve the methanogenic performance of microbial electrolysis cell for anaerobic digestion (MEC-AD) of waste activated sludge (WAS) via short-term batch experiments. However, its long-term effect is still unclear. This paper investigated how sludge-derived biochar improved the performance of MEC-AD under continuous operation for producing methane from WAS with different operating conditions. First, optimal external voltage was determined to be 1.5 V based on the methane production rates and current densities. Next, to investigate the effect of biochar on methanogenic performance of MEC-AD, the system performance was compared between ME1.5 (control) and MEBC1.5 (with biochar addition) in terms of methane productivity and process stability. The reactors were operated under different organic loading rates (OLRs), which were maintained by adjusting the hydraulic retention time (HRT). With the HRT gradually decreased from 10 d to 2.5 d, the methane production rates in ME1.5 and MEBC1.5 showed a trend of first increasing and then decreasing, and the methane production rates in MEBC1.5 was always higher than ME1.5. This indicated that biochar could enhanced the methanogenic performance under high-rate operation. The relative abundances of dominant genera on biocathode, Coprothermobacter, Fervidobacterium, Bellilinea, and Methanosarcina were increased by 34.1%, 186.6%, 130.5% and 9.5%, respectively. The KEGG pathway analysis showed that the abundances of genes associated with both acetoclastic and hydrogenotrophic methanogenesis pathways both increased. This study demonstrated the stimulatory effect of sludge-derived biochar in MEC-AD for biomethane production from WAS and also elucidated the related microbial metabolism.