电渗析离子交换膜生物反应器（EDIMB）的构建及其去除地下水硝酸盐的研究

The new technology for nitrate removal from groundwater is in great requirement in water treatment field. Based on the defects of traditional electro-dialysis and biological technology, this study will develop a novel Electro-dialysis Ion-exchange Membrane Bioreactor (EDIMB). EDIMB system utilized the selective permeability and microbial isolation character of the ion-exchange membrane, in which electro-migration and enrichment of nitrate occurred with denitrification simultaneously. Thus the transport resistance of nitrate between membranes was reduced and the energy was saved. In addition, the second pollution could be avoided. This proposed research will: explore the mass transfer mechanism of nitrate in EDIMB system; elucidate on the cooperative mechanism between electro-dialysis and denitrification process as well as regulation and control method; definite system principle; optimize the system operation mode; clarify the microbial community spatial distribution and its evolution; study the formation and development of membrane fouling and establish membrane fouling control strategy. The EDIMB system integrates the advantage of high stability and cleanness of electro-dialysis and the advantage of high effectivity of biological reduction. This proposed research aimed to improve the theoretical basis and application basis study of the EDIMB system, provide the theoretical and technical support for the treatment of groundwater.

开发降解地下水污染物硝酸盐的新技术，是水质净化的重要研究课题。基于现行电渗析和生物技术的各自缺陷，本研究将创新利用离子交换膜的选择透过性以及隔离微生物效应，构建电渗析膜生物反应系统（EDIMB），体系内硝酸盐的电渗析定向富集与生物反硝化降解同时发生，有效降低硝酸盐跨膜传质阻力，节约能耗并避免二次污染的产生。本项目拟从探索硝酸盐的跨膜传质机制着手，围绕电渗析与生物反硝化协同降解硝酸盐的作用及调控机制展开研究；明确该体系脱硝工艺原理，优化体系运行及操作模式；阐明体系中微生物群落结构及功能基因的空间分布和演替变化；考察膜污染产生和发展规律，建立膜污染的控制策略。EDIMB系统集成了电渗析过程的稳定性、清洁性和生物转化的彻底性等优点，是电化学生物水处理技术的一次新的拓展。本研究旨在完善EDIMB系统基础理论以及运行过程调控策略研究，为该系统在实际地下水污染修复中的应用提供理论基础和科学依据。

本研究创新构建电渗析膜生物反应系统（EDIMB）用于地下水硝酸盐的去除，考察电渗析与生物反硝化协同作用原理，明确体系脱硝机制，优化操作参数，确定最佳运行条件，并利用分子生物学手段探明微生物群落结构的空间分布和演替变化。.（1）建立EDIMB系统并对其运行参数优化。结果表明：阴极室和阳极室的最佳循环方式为外循环；在单纯ED模式下电压为5V时，NO3-的去除率为96.8%；最优膜处理方式为洗膜+预饱和处理。.（2）考察异养EDIMB系统对NO3-的处理效能。序批运行结果表明：NO3-迁移的动力学过程符合一级动力学模型，反硝化降解过程符合Michaelis-Menten模型，而生物室NO3-迁移和还原的整体动力学过程符合Zero－Michaelis-Menten模型。连续运行结果表明：最佳运行条件为HRT-W20.0h、HRT-B24.0h、电压6.65V、CH3COO-投加454.99mg/L，出水NO3-符合国家饮用水标准；微生物群落结构对有机碳源浓度的变化不敏感；体系中基因nirS表达优于narG，因此无NO2-积累。.（3）考察硫自养EDIMB系统对NO3-的处理效能。结果表明：该系统中NO3-的去除符合一级动力学模型；当电压为7.0V时，序批运行下40mg-N/LNO3-去除率高于94.6%，且出水无NO2-和微生物残留；系统在HRT-W16.0h、HRT-B12.0h条件下连续运行时，NO3-去除达到89.9%；Betaproteobacteria为硫颗粒表面的优势菌属，Gammaproteobacteria为硫颗粒间隙的主要菌属，CLSM表征证实反硝化菌向生物室出水侧富集，ATR-IR和SEM表征证实NO3-更易在膜表面富集，膜形貌变化对去除率影响不明显。.（4）初步ClO4-与NO3-共存时系统的处理效能，结果表明：最佳运行条件为HRT-W20.0h、HRT-B15.5h、电压10V和CH3COO-投加444.88mg/L时，NO3-及ClO4-去除率均在92%以上；Thauera、Azospira、Mesorhizobium和Curvibacte为优势菌属，有机碳源投加量和HRT-W是影响微生物群落结构的关键因子。. 本项目证实了新型EDIMB系统对水中NO3-处理的可行性和高效性，具有重要的科学意义和应用价值。