复合生物酶溶胞耦合导电介质介导微生物直接种间电子传递的剩余污泥产酸产甲烷机制研究

Severe land occupation and ecological hazards caused by the increasing excess sludge production from the sewage/wastewater biological treatment processes has been one of the grave environmental problems in China. Anaerobic digestion is an important technology for excess sludge stabilization and resource recovery. It is a key point that how to improve the sludge cell lysis and methanogenesis efficiency during the anaerobic digestion process. It is the foundation of breaking through these technology bottlenecks by in-depth investigations of the corresponding mechanisms. This project intends to investigate: the compound enzymes establishment and its performance of promoting excess sludge solubilization; the corresponding mechanism and regulations of butyrate type fermentation in the pretreated excess sludge anaerobic digestion process by emzymolysis; the system estabilishment of enhancing methanogenesis based on direct interspecies electron transfer among anaerobic microbes by conductive media addition and its corresponding mechanism. Reveal the corresponding mechanism of compound enzymes pretreatment for sludge cell lysis coupled with direct interspecies electron transfer among anaerobic microbes induced by conductive media in excess sludge anaerobic digestion process, which aims to boost volatile fatty acids and methane production. This project proposes a novel technology with efficient excess sludge anaerobic digestion treatment and carbon resource recovery rapidly, which is meaningful to both enriching anaerobic digestion mechanism of excess sludge and facilitating the development of anaerobic digestion technology. The project findings will provide important practical significance and actual application prospect for accelerating excess sludge hydrolysis process, shorting excess sludge anaerobic digestion time, improving the conversion rate of organic matter and methane yield and realizing the fast resource recovery, stabilization and reduction of excess sludge.

污/废水生物处理过程产生的大量剩余污泥所造成的土地侵占和生态危害日益突出，是我国面临的重大环境问题之一。厌氧消化作为剩余污泥稳定化和资源化的重要技术，如何有效提高其溶胞水解和产甲烷效能，是需要解决的关键技术问题，而对其机理的深入研究，则是突破这些技术瓶颈的基础。本申请课题拟开展复合生物酶的构建及其对剩余污泥的溶胞效能、酶溶污泥丁酸型发酵机制及定向调控、导电介质介导直接电子传递的厌氧产甲烷系统的构建及其强化产甲烷机制研究，揭示复合生物酶溶胞耦合导电介质介导微生物直接种间电子传递的剩余污泥产酸产甲烷机制。申请课题提出剩余污泥高效厌氧消化处理及快速资源化的一种新技术，对丰富剩余污泥厌氧处理理论、促进剩余污泥厌氧消化技术研究的发展具有重要科学意义。研究成果对于加快剩余污泥水解进程、缩短厌氧消化时间，提高有机质转化率和甲烷产率，实现剩余污泥快速资源化、稳定化、减量化具有重要现实意义和工程应用前景。

厌氧消化是剩余污泥资源化的重要方法，但存在水解慢、有机质利用率低、产甲烷效率低等问题，为实现剩余污泥的快速能源化，课题开展了复合生物酶构建及其对剩余污泥的溶胞效能与机制、酶溶污泥丁酸型发酵机制及调控、导电介质介导直接电子传递的厌氧产甲烷系统的构建、导电介质介导直接电子传递的强化甲烷发酵效能机制等研究。研究重要结果如下：1、构建了复合生物酶快速溶胞剩余污泥的水解体系，提出了优化控制参数，揭示了复合生物酶对剩余污泥溶胞机制，实现剩余污泥高效水解。溶菌酶、蛋白酶、α-淀粉酶、纤维素酶的最优投加比例为6:2:1:1，方式为先投加溶菌酶、水解60min投加α-淀粉酶和纤维素酶、水解120min投加蛋白酶、搅拌强度300rpm，SCOD达7121±354mg/L，水解时间由传统的3-5天减少至6小时，效能提升约35倍。2、实现了酶溶污泥的定向发酵产酸，酶溶污泥丁酸达到2589mg/L，控制条件是pH为6.5、ORP为-178mV、OLR为1.5gVSS/(L·d)-1和C/N为20/1。基于分子生物学手段阐明了发酵体系中微生物群落的动态变化，明确了优势菌门、纲、属，揭示了酶溶底物的代谢特性，阐明了环境参数、产酸类型和产酸微生物群落的相关关系。3、通过硝酸预氧化和共沉淀法负载的方法优化制备了Fe-PAC导电材料并进行表征，实现了以其为介质的丁酸型污泥发酵液底物的高效产甲烷。甲烷产量较传统工艺增加了50%以上、停留时间缩短30%以上、甲烷含量高达75%。4、研究揭示了导电介质对厌氧消化微生物种间电子传递的贡献机制，阐明了 DIET过程在Fe-PAC介导的丁酸型污泥发酵液产甲烷过程中途径，并从微生物基因组学方面阐明了DIET过程功能菌群的代谢途径和关键酶表达过程。.课题研究通过复合生物酶溶胞提高污泥水解效率，实现了酶溶污泥丁酸型发酵定向调控，以导电介质介导种间电子传递强化产甲烷进程，达到剩余污泥快速厌氧消化高效产甲烷的目的，研究成果不仅丰富剩余污泥厌氧消化理论，而且对剩余污泥快速资源化有重要的科学与工程意义。