基于厌氧颗粒污泥的CO甲烷化及有机废水处理耦合技术及机理研究

Biomass, organic wastes and coal can be converted to syngas via thermal-chemical conversion, which can be further converted to methane. The produced methane can be utilized as natural gas, and it is a research focus worldwide. Currently, the biomethanation of syngas is mainly achieved by chemical catalysis, which is a complex process with relatively high cost. The CO content in the syngas can be as high as 40-65%. Since CO can be converted to methane by anaerobic microorganisms, the present project proposes an innovative technology for simultaneous wastewater treatment and CO biomethanation by the utilization of anaerobic granular sludge. Anaerobic granular sluge is proposed to overcome the inhibition of CO to microorganisms. The effects of different CO concentration on the biomethanation kinetics of CO by anaerobic granular sluge will be studied, and the effects of CO addition on the wastewater treatment will also be investigated. Different methods to inject CO to the anaerobic reactor will be tested in order to overcome the gas-liquid mass transfer limitations to increase the CO conversion efficiency. The effects of CO addition on the microbial community structure, functional genes composition and the distribution of microorganisms in the granules will be analyzed by metagenomic analysis and FISH technology, which will also reveal the microbial and metabolic characters of the mixed culture that can convert CO to methane. The project will provide theoretical and technical basis for the application of the proposed technology.

利用生物质、有机废弃物及煤通过热解制取合成气并进一步转化为甲烷进而替代天然气是国际及国内的研究热点。目前合成气甲烷化主要采用化学催化法，其成本较高，操作较复杂。合成气中CO含量可达40-65%，基于厌氧微生物能够转化CO为甲烷的原理，本申请在前期可行性研究的基础上，提出利用厌氧颗粒污泥同步实现有机废水处理及CO甲烷化的耦合新技术。针对CO对大部分微生物活性有抑制，本项目拟采用厌氧颗粒污泥提高微生物对CO的耐受性，研究不同CO浓度下厌氧颗粒污泥转化CO为甲烷的动力学，同时研究CO加入后对有机废水厌氧降解的影响，探索采用不同的CO供气方式，提高CO气液传质速率进而提高CO的转化效率；结合宏基因组学分析及FISH技术，阐明CO对厌氧颗粒污泥群落结构、功能基因组成及不同微生物在颗粒污泥中分布的影响，揭示CO转化为甲烷的混合微生物群落特征及代谢途径。本项目将为该新技术的工程应用提供技术支持和理论依据

CO是合成气的主要成分，可以由有机废物和生物质的气化产生。将合成气转化为甲烷进而取代天然气可以缓解我国对天然气的需求。CO可以通过厌氧消化（AD）转化为甲烷，然而，由于其对微生物的毒性以及关于CO转化微生物的有限知识，其仍然具有挑战性。在本研究中，厌氧颗粒污泥（AGS）被用于废水和CO的同步生物甲烷化处理。间歇实验表明，与之前报道的悬浮污泥（小于0.25个大气压）相比，AGS耐CO分压高达0.5atm，而不影响有机废水降解的能力。在上流式厌氧污泥床（UASB）反应器中的连续实验表明，AGS可以通过应用气体循环将有机废水和CO有效地转化成甲烷。在UASB反应器中加入CO增强了耗氢CO氧化途径，导致细胞外高分子物质增加，改变了AGS的形态，并显着改变了AGS的微生物群落组成。通过宏基因组分析揭示了与CO转化有关的微生物种类及其功能。结果表明，70个重组基因组中的23个（GBs）在CO加入后得到富集并含有CO转化的基因，其中大部分以前没有在基因组水平上表征过。转化CO的微生物可能在分类学上比以前已知的更加多样化，并且在厌氧消化过程中可以参与到多个代谢步骤。本研究也发现大部分GB与还原性三羧酸（TCA）循环结合来进行CO的氧化进而实现对CO的利用。本项目的研究成果为该新技术的工程应用提供技术支持和理论依据。