基于MBR金属赋存形态的共存离子体系生物絮凝行为解析

Comprehensive understanding the mechanism of bioflocculation will help us to propose more effective retarding membrane fouling strategies by modification of mixed liquor characteristics in membrane bioreactor (MBR), which will also benefit the application to the actual engineering optimal design. With the extending the scope of application for MBRs and the development of innovative high rejection membrane, which leads to metals ions accumulation with seriously impacts on bioflocculation. For better understanding the effects of metals ions on bioflocculation, the bioflocculation behaviors in the coexisting metals ions based on the speciation of metals will be studied. The first objective of this study is to investigate the effect of three categories of metal ions speices on the mixed liquor characteristics and membrane fouling. Microbial community diversity, bioflocculation, microbial metabolites, filterability of mixed liquor and fouling layer will be investigated to characterize the distribution mechanism of metal ions speices. On the basis of these, futher investigation to explore the effect of coexisting metal ions, including same or different valence metal ions, on mixed liquor characteristics and membrane fouling, and the synergistic or antagonistic effect of coexisting exchangeable metals ions on bioflocculation will be revealed. Moreover, it was necessary to assess the applicability of multivalent metal ions on membrane fouling mitigation in MBR with treating salt wastewater. Base on this study, it would be reveal the essence between metals ions and bioflocculation, which will provide the theoretical basis for the application of the multivalent metal ions to reduce the membrane fouling. Moreover, the results obtained in this research are expected to formulate effective strategies for reducing fouling in treating salinity wastewater with MBR process.

全面认识MBR生物絮凝机理，对于膜污染控制措施的开发及工程优化具有重要意义。随着MBR应用领域不断扩大及高截留膜在MBR中的应用，金属离子对生物絮凝的影响更为突出。本课题拟从金属赋存形态角度开展共存离子体系MBR生物絮凝行为的研究：系统考察3类典型金属赋存形态对MBR混合液性状及膜分离的影响，结合微生物群落多样性、生物絮凝性、微生物代谢产物特性、混合液可滤性及膜污染层等分析手段，阐明金属赋存形态对生物絮凝的影响；探索同价或异价金属离子共存体系混合液特性及膜分离机制，揭示共存可交换态离子对生物絮凝的协同或拮抗行为规律，阐明不同种类及价态的金属离子共存时生物絮凝机理；验证高价金属离子共存对MBR处理含盐废水调控的适用性。以期深入认识金属离子对生物絮凝作用的本质，为应用高价金属离子协同调控MBR混合液提供理论依据，从减缓膜污染的角度为MBR处理含盐废水提供新策略。

膜生物反应器(MBR)技术已成为污水处理及回用领域极具竞争力的选择，然而膜污染问题极大限制了该工艺进一步大规模推广应用。大量研究表明，活性污泥中的胞外聚合物(EPS)是膜污染的关键物质，与活性污泥的生物絮凝及膜污染行为密切相关。由于EPS负载大量的负电官能团，废水中广泛存在的金属离子势必与EPS产生作用，从而影响活性污泥的生物絮凝行为。不同种类及价态的金属离子对生物絮凝及污泥可滤性存在不同的影响，因而系统考察典型金属赋存形态对MBR混合液性状及膜分离的影响，对于我们采用高价金属离子调控污泥混合液可滤性，进而延缓膜污染具有十分重要的意义。本课题紧紧围绕共存离子体系中活性污泥生物絮凝与膜污染行为内在关联这一核心科学问题展开，结合污泥特性指标及生物膜污染检测手段，系统开展金属离子对MBR运行效能的影响。本课题研究结果揭示了：（1）金属离子单独存在对MBR运行特性影响，包括微生物活性、污泥混合液可滤性、生物絮凝性及膜污染；（2）相同价态及不同价态离子共存体系对生物絮凝及膜污染的影响机制；（3）金属离子在污泥中的分布规律及其对EPS组成的影响机制；（4）高盐度冲击下强化生物絮凝机理。本项目研究的科学意义在于考察不同种类及价态的金属离子与污泥混合液共存体系，可深入认识金属离子对生物絮凝作用的本质；其工程意义在于应用高价金属离子协同调控MBR混合液，从减缓膜污染的角度为MBR稳定运行提供新策略。