基于纳米红外光谱原位成像的MBR膜污染机制研究

Membrane fouling in MBRs has not been well revealed so far, which strongly limit the application of MBRs for wastewater treatment. In this proposal, nanoscale infrared spectroscopy (AFM-IR) will be used to characterize the development and control of membrane biofouling, which can provide in situ imaging of the key functional groups in foulants. The main investigation and objectives include the followings: (1) This work will reveal the spatial distribution and stratification behavior of functional groups in membrane foulants formed in MBR and batch membrane filtration systems, and then make clear the correlation between membrane flux, TMP and functional groups. (2) The cell-cell, cell-ion, and cell-membrane interactions will be explored based on nanoscale infrared spectroscopic imaging and QCM-based qualification of selected pure-cultured bacteria strains. (3) This work will also reveal the response of functional groups in membrane foulants to NaClO backwashing, and look for the correlation between typical operating conditions (e.g., NaClO concentrations, pH, and backwash period) and fouling control efficacy. Overall, this proposal aimed to identify the spatial distribution of core functional groups in cake layer, reveal the interaction mechanisms between bacterial cells and membranes and those between membrane foulants and NaClO, finally improving the understanding of membrane biofouling and aiding in the control of biofouling in MBRs.

如何明晰膜污染物形成机制是限制MBR膜污染识别与控制的关键科学问题。本项目拟采用纳米红外光谱技术对MBR膜污染的形成和控制过程进行原位成像研究。通过分析膜污染物中核心官能团的空间分布和层化现象，并借助短期膜过滤实验，在官能团水平阐明膜通量、跨膜压差和膜污染物核心官能团间的相互关系。通过对关键膜污染微生物的细胞表面进行光谱成像和微界面（QCM-D）定量分析，探究菌与菌、菌与离子、菌与膜之间的相互作用，探明关键膜污染微生物在膜表面的沉积以及生物膜形成规律。研究膜污染物（有机物和菌）核心官能团对NaClO清洗的响应机制，阐明反洗参数对污染物官能团的影响，并构建NaClO浓度、pH值和反洗周期等关键参数和膜污染控制间的关联关系。通过以上研究，本项目有望在分子水平辨识膜污染物在滤饼层中的分布规律，探明微生物与膜的作用机制，揭示膜污染物对化学清洗的响应机制，最终为MBR膜污染识别与控制提供理论支撑。

在国家自然科学基金面上项目（编号: 51878675）的资助下，项目组成员借助中山大学的科研条件，通过4年的科研努力，顺利完成了该项目的主要研究内容，基本达到了预期研究目标。利用显微红外技术，解析了典型化学清洗剂NaOCl应用于膜清洗过程中的膜损伤和膜孔阻塞机制；系统研究了典型膜污染控制策略应用过程中的基础问题，揭示了膜污染的分子特异性和生态机制；基于膜表面生物活性层构建，开发了新型营养液反洗原位产气减缓膜生物反应器（MBR）膜污染方法，发现原位产生的氮气延缓膜污染的同时还改变了膜污染物层结构；基于微生物生态学研究方法，阐释了污泥絮体在形成生物膜或膜污染过程中的絮体尺寸依赖关系，系统评估了关键膜污染物（胞外聚合物和溶解性微生物代谢产物）的微生物降解动力学和群落响应行为，发现了污水管道微生物的迁移改变了MBR群落生态且有助于延缓膜污染，解析了生物膜发展过程中的群落演替、群落组装及种间相互作用规律并建立了生物膜动态发展过程与工艺运行效能之间生态学联系；基于层层组装和仿生技术，研发出一系列新型复合膜，经工艺运行发现，研发的新型TFC膜均具有优良的抗膜污染行为和运行稳定性。在该项目资助下，本课题资助成果发表论文29篇；获授权国家发明专利7项；已培养4名硕士毕业生、6名博士毕业生。