厌氧膜生物反应器中微生物胞外聚合物对水力剪切的响应机制及其膜污染效应

Anaerobic membrane bioreactor (AnMBR) is a promising technology for wastewater treatment. It has the potential to achieve net energy production while meeting stringent effluent standard. However, membrane fouling resulting in lower operational efficiency and higher energy consumption hinders the industrial application of AnMBR. Microbial extracellular polymer substances (EPS) is the predominant matter that cause the membrane fouling in AnMBR. Differing from aerobic membrane bioreactor, organic loading is high, microorganism grow slowly and hydrodynamic shear is weak owing to the absence of aeration in AnMBR. These different operating conditions lead to the difference in the production, composition and micro-structure of EPS between these two categories reactor, which influence its physiochemical characterizations and membrane fouling capability further. In addition, hydrodynamic shear is used as a common method for membrane defouling. It will effectively benefit membrane fouling control to optimize the hydrodynamic condition. Therefore, this project will analyze the production regularity and physiochemical characterization of microbial EPS in AnMBR, study its membrane fouling capability and hydrodynamic regulation mechanism of membrane defouling, and explore its micro-structure. It will provide the theoretical fundamentals and technical supports for membrane defouling and large-scale application of AnMBR.

厌氧膜生物反应器（AnMBR）是一项具有应用前景的废水处理技术，它能够在满足严格出水排放标准的同时产生能源。然而，膜污染导致其效率降低、能耗增加，阻碍了AnMBR的规模化应用。微生物胞外聚合物（EPS）是引起AnMBR膜污染的主要物质。相对于好氧膜生物反应器，AnMBR负荷较高、微生物生长缓慢，缺少持续鼓气产生的强水力剪切，从而使得这两大类反应器在EPS的产生、组分和微观结构等方面存在不同程度的差异，进而影响EPS的物化特性和膜污染效应。此外，水力剪切是常用的膜污染调控方法，优化水力条件能更有效地控制膜污染。因此，本项目针对AnMBR膜污染比较严重的问题，拟通过分析AnMBR中微生物EPS的产生规律及其物化特性，研究EPS的膜污染效应及其水力调控机制，并探索EPS的微观结构，深入认识AnMBR膜污染的水力调控机制，为减轻其膜污染、实现规模化应用提供科学依据和技术支撑。

厌氧膜生物反应器结合厌氧过程和膜分离技术，在回收沼气作为能源的同时提高了反应器出水的水质，是一种具有广阔应用前景的废水生物处理技术。然而，反应器中膜组件容易被污染堵塞限制了其大规模的应用。微生物EPS是膜污染前期的主要污染物质之一。本项目从宏观的反应器运行，介观的膜污染效应以及微观的光谱成像分析多尺度探索了厌氧膜生物反应器中微生物胞外聚合物（EPS）的产生，膜污染的机理及其微观的结构和组分。研究结果表明厌氧膜生物反应器中溶解性EPS的浓度较高且波动较大，而松散结合型EPS和紧密结合型EPS的浓度较低且较为稳定。微生物EPS引起膜污染主要以膜孔堵塞为主，而在钙离子存在的条件下，EPS-钙在膜表面形成致密的污染层，反而一定程度减少了膜污染，有利于水力剪切调控减缓膜污染。在微观状态下，EPS呈现三维空间结构，不同形态的物质可能对应糖蛋白、蛋白质和类胡萝卜素，其中丝状物质主要成分为多糖。这些研究结果加深了对厌氧膜生物反应器中微生物EPS的认识，有助于在将来提出有效的应对策略减缓厌氧膜生物反应器中的膜污染。