超滤饮用水处理中化学清洗造成膜损伤的机理及其调控研究

化学清洗是超滤系统运行中的必要环节，但化学清洗造成的膜损伤会影响膜的截留性能和使用寿命，使超滤出水的生物安全性降低，并最终导致膜的提前更换而使水厂成本大幅增加。本项目针对饮用水处理中广泛使用的PVDF超滤膜，以膜损伤评价-膜损伤机理解析-膜损伤调控为主线，通过模拟化学清洗实验研究膜的使用性能、界面性质和微观结构及其化学组成等不同性质对氧化剂、酸、碱等清洗剂的敏感性，建立科学合理的膜损伤评价方法体系；利用耗散型石英晶体微天平探明化学清洗剂作用下膜主体材料和添加剂的降解特性，通过多种结构表征手段揭示膜损伤前后膜材料组成和分子结构的变化，阐明化学清洗导致膜损伤的途径和机理；明确化学清洗条件对膜损伤的影响规律，提出能够在保证化学清洗效率的前提下控制膜损伤的化学清洗策略。本研究的预期成果将为饮用水处理中超滤膜的安全有效化学清洗提供理论依据和技术支撑。

Chemical cleaning is a vital step in maintaining the permeability of the membrane, but membrane degradation caused by chemical cleaning might compromise rejection performance and lifetime of the membrane, which would raise the risk of virus contamination in product water and eventually lead to a substantial increase of cost due to membrane replacement. Based on the idea of membrane degradation assessment - degradation mechanism investigation - control of membrane degradation, this project tries to explore the mechanisms and control of degradation of PVDF ultrafiltration membrane. Firstly, the sensitivity of various properties of membrane, including membrane performance, surface properties and microstructure as well as chemical composition, towards cleaning agents such as oxidant, acid and base will be investigated, and proper techniques to assess membrane degradation will be identified. Moreover, in order to illustrate the pathway and mechanism of membrane degradation, the degradation behavior of PVDF polymer and additive will be studied in-depth by QCM-D, and change in composition and molecular structure of membrane material will be characterized systematically. Besides, the influence of chemical cleaning parameters on membrane degradation will be investigated, and accordingly chemical cleaning strategies to minimize membrane degradation without compromising cleaning efficiency will be proposed. This study will provide theoretical and technical supports for the safe and effective chemical cleaning of ultrafiltration membrane in potable water treatment.