基于微生物污染层流变特性的微观流场调控纳滤膜污染研究

Rapid urbanization requires efficient and effective wastewater reclamation to meet the increasing water demand and wastewater discharge in the metropolis. Nanofiltration (NF) membrane systems exhibits great potential and has been widely applied for wastewater reuse. However, similar to other applications employing membrane for solid liquid separation, accumulation of bio-solids on membrane surface, i.e. biofouling, significantly limits NF membranes’ performance. This project aims to explore the biofouling mechanism and seek for effective fouling control methods through a three-step research: 1) characterization of the structure performance of biofilm on NF membrane surface; 2) characterization of the macroscale rheological properties of biofilm; and 3) fouling control by Micro-fluid field. Firstly, the biofilm structural characterization will be investigated systematically, through evaluating the impact of biomass growth response and biofilm structure on membrane performance under operational hydraulic conditions. Next, the rheological properties of biofouling layer will be investigated, and the relationship between rheology properties and structure characterization of biofouling layer will be investigated. Furthermore, empirical equations on the relationships between micro-fluid field near membrane surface, properties of biofilm and biofouling control efficiency will be built up, based on which, spatial and temporal anti-biofouling strategies will be summarized and proposed. The study will provide theoretical and technical supports for biofilm control in nanofiltration membrane systems and can be applied in advanced wastewater treatment and reclamation processes.

再生水在城市水循环中发挥重要介质作用；以纳滤膜为核心的高效处理技术是再生水水质保障的关键技术选择之一。纳滤用于再生水产水中膜表面微生物污染层会导致产水效能下降，本项目基于“结构特性解析-流变特性阐释-微观流场调控”的研究主线，采用数值模拟和实验研究相结合的方法，通过解析膜表面微生物污染层的结构特性，阐明不同水力条件下微生物污染层结构的变化规律对膜滤性能的影响机制；进而探究微生物污染层流变特性的影响机制，揭示流变特性与结构特性的关系；最终，以微观流场作用和微生物污染层流变特性响应两方面系统分析结果，建立水力强化调控膜污染的量化体系，构建微观流场调控纳滤膜污染的特征技术策略。本研究预期成果将为再生水产水过程纳滤膜微生物污染的有效控制提供理论依据和技术支撑。

水资源的短缺和水源水质的不断恶化增加了社会对再生水的需求，从而推动了再生水产水技术的迅猛发展。当纳滤用于再生水产水时，待处理的二级出水中含有大量的微生物和丰富的营养物质，膜滤将微生物与营养物质富集，使膜表面极易产生微生物污染(Biofouling)，从而导致产水通量减小、出水含盐量升高和系统运行能耗增加，进而使得膜系统产水效能急剧下降。因此，高效调控纳滤膜表面微生物污染，是提高纳滤产水效能的关键。本项目解析膜表面微生物污染层结构的变化规律，阐明了微生物污染层的流变特性与结构特性的关系，初步建立了以膜表面微观流场和微生物污染层流变特性为量化参考的体系；在此基础上，构建了以电化学控制纳滤膜生物污染途径，主要构建电化学处理纳滤浓缩液产物协同控制纳滤膜表层生物污染途径，阐明BDD电极在城镇污水回用背景下氯胺产物对纳滤膜生物污染特性影响规律。在国内外高水平期刊上发表论文16篇，其中SCI检索15篇，授权实用新型专利4项，培养硕士生6名。后续研究将在此基础上将膜表面流态特征值与微生物污染层的流变特性定量耦合衔接，明确水力控制与电化学处理协同控制纳滤过程中生物污染。本研究预期成果将为再生水生产过程纳滤膜微生物污染的有效控制提供理论依据和技术支撑。