厌氧膜生物反应器中共生菌系的氢传递机理与控制研究

In recent years, interests in anaerobic membrane reactor (AnMBR) have increased because of the merits such as high concentration of biomass and the decoupling of hydraulic retention time and biomass retention time. The AnMBR process can be used in the treatment of wastewater and organic solid wastes. In a vacuum-driven submerged AnMBR, vigorously bubbling biogas flow across the membrane surface to prevent membrane fouling. The upflow rate of the biogas exceeds that in widely used up-flow reactors. Intensive biogas mixing could result in the disruption of micro-structure of syntrophic consortia of acetogenic bacteria and methanogenic bacteria. Microbial activity would be negatively affected and system operation would be deteriorated due to the accumulation of VFA. In most cases, the stability of an AnMBR was analyzed using the process indicators such as VFA, pH and methane content. However, whether an AnMBR can be used in a high OLR process or the biogas recycling rate can be further increased to extend the duration of membrane operation? In addition, does the separated AnMBR system is necessary or more efficient when treating high-solid waste? The hydrogen transfer in a syntrophic bacterial was the key mechanism that would theoretically answer these questions..The following experiments are proposed in this project to accomplish the overall objects. Firstly, the physical structure and microbial community shifts in an AnMBR will be investigated according to different operation regimes. The relationship of the micro environment with the apparent AnMBR performance will be established to provide information for system operation. Secondly, the average distance between syntrophic bacterial cells in dispersed and floc community and the hydrogen diffusion flux will be calculated based on Fick's law and diffusion model. The thermodynamic free energy of acetate production from propionate, butyrate and ethanol will be evaluated based on free hydrogen in liquid phase. Finally, experiments will be designed to simulate the operation of a separated AnMBR configuration to investigate the flocculation of the dispersed cells by high speed biogas recycling in a membrane zone. The optimal operation strategy of a separated AnMBR system would be obtained by adjusting the distribution of sludge volume in membrane zone and in the main digester..Through this project, the mechanism and function of hydrogen transfer in a AnMBR syntrophic bacterial community will be obtained to facilitate the control of an AnMBR process. The achievements of this research will provide informative and valuable knowledge about AnMBR system and improve the application of membrane technology in anaerobic process.

厌氧膜生物反应器(AnMBR)具有可维持高生物量和分离停留时间的优点，在污水和废弃物厌氧消化处理中均可应用，被视为新一代的厌氧消化工艺。在AnMBR中，为缓解膜的污染，沼气以远超过现有升流反应器的速率循环冲洗膜面，所引起的强烈气液混合影响共生菌系(产氢产乙酸和氢源甲烷合成的重要场所)的团聚和氢传递，导致出现有机酸积累等一系列影响工艺稳定性的问题。目前，对这些因素的作用机理还缺乏认识，限制了反应器的工艺发展。本研究拟考察反应器运行条件对共生菌系的分散、聚集和细胞间距等微环境变化的影响；基于费克定律和传质模型，解析氢在共生菌系内的种间传递、在液相主体的分子扩散和在气液两相过饱和分配的途径与通量，以液相游离氢表征乙酸化过程的真实自由能和推动力；考察分散菌系发生再聚集的规律与条件，建立时空交替下的反应器控制方法，为AnMBR的工艺开发和过程控制提供理论支撑。

厌氧膜生物反应器(AnMBR)具有可维持高生物量和分离停留时间的优点，在污水和废弃物厌氧消化处理中均可应用，被视为新一代的厌氧消化工艺。在AnMBR中，为缓解膜的污染，沼气以远超过现有升流反应器的速率循环冲洗膜面，所引起的强烈气液混合影响共生菌系(乙酸氧化和氢源甲烷合成的重要场所)的团聚和氢传递，导致出现有机酸积累等一系列影响工艺稳定性的问题。目前，对这些因素的作用机理还缺乏认识，限制了反应器的工艺发展。本研究拟考察反应器的行条件对共生菌系的分散、聚集和细胞间距等微环境变化的影响；基于费克定律和传质模型，解析氢在共生菌系内的种间传递、在液相主体的分子扩散和在气液两相过饱和分配的途径与通量，以液相自由氢表征乙酸化过程的真实自由能和推动力；考察分散菌系发生再聚集的规律与条件，建立时空交替下的反应器控制方法，为AnMBR的工艺开发和过程控制提供理论支撑。.课题在长期连续运行的厌氧膜生物反应器平台上，获得了气升式AnMBR中气相氢分压和有机酸随工艺条件变化的规律，从热力学的角度分析了氢分压对共生菌系降解丙酸的影响，通过对比全混式反应器发现了容积负荷的提高是引发氢分压抑制有机酸降解的重要因素；采用Unisense原位测试系统发现了在高负荷AnMBR中存在过饱和的溶解性氢，获得了液相氢降解动力学特征，在乙酸基质AnMBR中发现了嗜氢产甲烷菌占优的古菌群落，结合反应器嗜氢活性，揭示了存在乙酸共生产甲烷途径，为AnMBR反应器产甲烷路径的研究提供了有力的支撑；针对AnMBR中存在较高氢分压和丙酸积累的现象，添加300 mg/L硫酸盐作为外源电子受体成功的提高了氢和有机酸的转化能力，实现了高负荷[14.6 kg-COD/(m3•d)]下的低有机酸残留；通过吉布斯自由能计算和16s rRNA群落结构分析获得了外源电子受体添加下氢、乙酸和丙酸的硫酸盐还原和共生氧化的转化途径，揭示了氢分压仍是丙酸共生降解的热力学限制因素，为外源电子受体调控AnMBR氢传递路径的研究提供了新的思路。.课题实施以来，已发表期刊论文6篇，其中SCI收录5篇，授权专利3项（发明专利1项，实用新型专利2项），合作撰写英文专著一章内容，培养毕业3名研究生。