微生物电解促进剩余污泥产甲烷及电极-生物界面电子还原机制

A substantial acceleration of methane production is a key evolution for energy recycling from waste activated sludge (WAS) in anaerobic digestion (AD), which is the essential driving force for a waste water treatment plant to choose sludge utilization disposal. This project targets on enhancement of WAS conversion and methane production in a novel process of microbial electrolysis accelerating anaerobic digestion (ME-AD) for methane production. The mechanism of electron reduction on electrode-biofilm interface and energy recovery enhancement will be disclosed, aiming to accelerate the low carbon conversion rate and low methane production rate in conversional WAS treatment. A dominant communities of hydrogenotrophic methanogens will be enriched by microbial electrolysis biocathode in ME-AD system, rather than acetotrophic methanogenesis as dominant functional group in conversional AD. Microelectrode detection system will be used to analyze recovery process and by-products in situ on the electrode-biofilm interface. New alloy cathode will be tested to optimize biocathode functions on key communities of electrode respiring bacteria, methanogens and fermentative bacteria. A further enhancement will be achieved by signal molecule regulation to improve cell-cell communications among these three groups. By coupling the advantages of ME and AD system, it is potential to overcome the limiting step from complex organics to suitable carbons for methanogens. Moreover, methane production rate can be significantly accelerated by hydrogenotrophic methanogenesis. A novel technology of enhanced energy recovery from waste activated sludge will be put forward in the project.

城市剩余污泥厌氧产甲烷速率能否获得突破性提高是推动污水处理厂污泥能源化处置的重要驱动力。本课题以提高城市剩余污泥转化和产甲烷速率为目标，重点揭示微生物电解促进厌氧消化（ME-AD）体系电极-微生物界面的电子传递与还原过程及污泥产甲烷强化机制，解决传统剩余污泥能源回收过程碳源转化速率低和产甲烷速率低的两个关键限制因素。本研究将通过微生物电解生物阴极构建氢营养型产甲烷菌为优势菌群的新型剩余污泥厌氧消化体系，基于不同基底材料电极-微生物界面间的电子还原原位解析，采用微电极系统对新型基底材料与生物膜功能菌群（电子传递菌、产甲烷菌、发酵菌）间的影响与作用过程进行机制解析，建立微生物信号分子对主要功能菌群调控策略。微生物电解与厌氧发酵的优势耦合将能够实现剩余污泥中大分子有机质降解速率慢的跨越性转化，生物阴极还原过程将有效促进氢营养产甲烷菌的产气速率，最终形成剩余污泥促进产甲烷能源回收强化技术。

针对传统厌氧消化产甲烷难以形成嗜氢产甲烷为主要路径的电子供给限制，重点围绕微生物电解促进厌氧消化系统中电极生物膜内电子传递/质传输子影响，以及生物电极介导的复杂碳源转化和甲烷化路径这两个关键科学问题，系统开展了微生物电解促进剩余污泥产甲烷及电极-生物界面电子还原机制的研究工作，为有效提升产甲烷效能提供了重要的理论依据。研究提出了阴极电子驱动质子还原并原位利用提升嗜氢产甲烷路径原理，解析了生物阴极胞外电子传递路径对产甲烷的贡献率；构建了微电极与循环伏安扫描原位分析方法，揭示了阴极生物膜内的质子梯度变化规律，发现了电极界面超量富集的耐碱嗜氢产甲烷菌，阐明了生物阴极内氢还原二氧化碳反应的热力学优势，为调控嗜氢产甲烷路径提供了技术思路；建立了通过外电压定向驯化和富集电极生物膜的方法，发现了外源信号分子调控胞外电子传递功能菌成膜优势作用；研究了贵金属铂碳电极的替代材料，深入分析了典型金属阴极材料（铜、镍、不锈钢）与功能菌群构建关联影响，揭示了泡沫镍阴极对电极催化产甲烷的提升效果；利用电子传递衡算明晰了电辅助路径对系统产甲烷的贡献，揭示了生物电极电子分流对厌氧系统代谢流向的影响及作用规律；基于生物电极促进原理以及辅助电压强化厌氧产甲烷，自主设计了生物电解强化型复合厌氧产甲烷工艺。项目成果共发表基金标注的SCI论文22篇，其中发表在Water Research、Applied Energy、Chemical Engineering Journal等一区期刊11篇； 完成Elsevier出版专著《Microbial Electrochemical Technology》的专著章节1篇；相关技术原理及工艺申请专利4项，项目研发期间授权2项。