群体感应淬灭菌控制垃圾渗滤液MBR膜污染性能及作用机制

Membrane bioreactor (MBR) has been widely used for landfill leachate treatment as an advanced wastewater treatment technology to meet more stringent wastewater discharge standards. However, membrane biofouling is still a bottleneck in extensive growth of MBR markets as a result of high operating costs. Many techniques, such as modification of the membrane surface, physical and chemical cleaning, have been attempted to mitigate membrane biofouling. Since biofilm formation on the membrane surface is not tackled, all these approaches have limitations in mitigating membrane biofouling. Quorum quenching (QQ) bacteria has been shown to reduce bacterial cell-to-cell communication (quorum sensing, QS) which determines biofilm formation, thereby retarding biofilm development on the membrane and hence open a new avenue for minimizing biofouling. Therefore, the main objective of this project is: 1) to investigate the concentration and composition of QS signals molecules in the MBR for landfill leachate treatment; 2) to investigate the performance of membrane biofouling mitigation in MBR for landfill leachate treatment by QQ bacteria entrapped in alginate beads; At last, the involved mechanisms why QQ bacteria entrapped beads are efficient in mitigating membrane biofouling will be revealed in terms of bacterial QQ activity, QS signals molecules concentration, soluble microbial product concentration, extracellular polymeric substance concentration, membrane filtration resistance and characterization of fouled membrane. On the basis of the above studies, we anticipate this work will provide guidance for development of feasible methods to control membrane biofouling and minimize energy cost in MBR for landfill leachate treatment.

以MBR为代表的膜集成水处理工艺已被广泛应用于垃圾填埋场渗滤液的处理，但膜污染带来的高能耗一直是限制MBR推广发展的瓶颈性问题。传统技术常采用膜表面改性、物理/化学清洗等方法减缓膜污染，但这些方法并不能从根本上抑制MBR膜表面生物膜的形成。群体感应淬灭（QQ）菌可通过分解调控微生物形成生物膜的群体感应（QS）信号分子，进而抑制生物膜的形成，这为控制MBR膜污染提供了一个全新的途径。基于此，本项目拟在解析渗滤液MBR单元QS信号分子赋存规律基础上，分别以模拟和实际垃圾渗滤液为底物，通过包埋固定已分离获得的高效QQ菌，考察QQ菌减缓渗滤液MBR膜污染性能。从QQ菌活性、QS信号分子含量、溶解性代谢产物含量、污泥胞外聚合物分泌、膜过滤阻力以及膜表面污染表征等方面，初步阐明QQ菌控制渗滤液MBR膜污染的作用机制，为高浓度渗滤液处理过程MBR膜污染控制和节能降耗新技术研发提供理论依据。

以MBR为核心的膜组合工艺广泛地应用于垃圾渗滤液处理，但膜污染引起的高能耗仍是限制MBR更广泛推广的瓶颈性问题。传统膜改性和物化清洗方法不能从根本上抑制膜表面生物膜的形成，群体感应淬灭（QQ）菌可分解主导微生物形成生物膜的群体感应信号分子（AHLs），为控制MBR膜污染提供了全新途径。本项目以该新型膜污染控制方法为研究对象，通过比较不同QQ菌株耐盐能力、降解AHLs信号分子速率等，优选了具有高效性能的Rhodococcus sp.QQ菌株。借助Online SPE-LC-MS/MS方法，明确了MBR单元AHLs信号分子主要种类和含量。在此基础上，重点研究了QQ菌在不同盐度、模拟废水和渗滤液等水质下减缓MBR膜污染效能，探明在<0.1%NaCl、1%NaCl和渗滤液条件下，QQ菌分别可以减缓膜污染3.15倍、4.77倍和7.59倍。同时，对比分析了QQ菌调控前后膜污染、水质和AHLs等主要特性参数，从“AHLs模型化合物降解-MBR污泥-EPS-AHLs-膜滤饼层”相互作用关系，解析了QQ菌可以提高反应器中污泥QQ活性，降低反应器上清液中AHLs信号分子含量，减少EPS分泌，影响膜滤饼层EPS和微生物含量分布，进而减缓膜污染的作用机制。本项目为渗滤液乃至其它高浓度有机废水MBR处理过程膜污染控制和节能降耗新技术研发提供理论依据和技术指导。