城市再生水利用过程中低剂量污染物的高效去除机制

Key scientific issues related to the practice of reclaimed water utilization is how to efficiently remove the recalcitrant organic compounds and heavy metals occurring at low concentration in reclaimed water and solve the contradiction between high-level disinfection and disinfection by-products (DBPs) generation in water treatment, so that the overall biotoxicity of reclaimed water would decline and the safe utilization of reclaimed water can be ensured. Therefore, this project will first screen the risk factors generated during the urban sewage regeneration and reuse processing, including pathogen and trace poisonous and harmful chemicals, such as organic pollutants and heavy metals. Then the preparation of nano-materials as catalysts, the cooperative principles of advanced oxidation technology, the process control and the construction of techniques for efficient removal of hazard materials in reclaimed water will be discussed. We focus on the preparation of photocatalyzer which can act under visible light and achieve high performance on the separation of electron-hole pair. At the micro level the interface process between pollutants and catalytic materials and their reaction mechanism will be clarified, followed by the establishment of optimum operation and regulation mechanisms of photocatalytic reaction for reclaimed water disposing. Taking the photocatalytic reactor as the core unit, the best technique combination and process optimization modeling adapt to efficient removal of pollutants at low concentration in water will be constructed. The innovation and breakthrough in process, mechanism, key technique and process principle for disposing reclaimed water by photocatalyst safely and efficiently, so that safe reclaimed water can be obtained and the health and ecological risk occuring during the usage of the reclaimed water accordingly reduce.

如何高效去除再生水中的难降解有机物与重金属等低剂量有毒有害化学物质，解决病原微生物灭活与消毒副产物生成的矛盾，实现再生水综合生物毒性消减，以保障再生水水质安全是城市再生水利用实践中亟待解决的关键科学问题。为此，本项目在全面识别城市污水再生利用过程中病原微生物、有机污染物和重金属等微量有毒有害化学物质等风险因子的基础上，以纳米催化材料的制备-原理协同-过程调控-工艺构建为主线，重点研究可实现可见光反应和电子空穴对高效分离的光催化剂的制备与调控；在微观层次上阐明污染物与催化材料的界面过程及其反应机理，建立针对不同用途再生水水质特性的光催化最优化运行调控机制；以光催化反应器为核心单元，构建适应低剂量污染物高效去除的最佳技术组合及工艺优化模式；在再生水光催化安全高效处理的过程机理、关键技术和工艺原理上实现创新突破，以保障再生水的水质安全、降低再生水利用过程中的健康与生态风险。

项目以城市生活污水处理厂尾水和工业园区污水处理厂出水中存在的低剂量有害有机污染物、重金属离子、氮磷化合物的零排放为目标, 建立了电化学发光、量子点荧光探针、阳极溶出高灵敏快速识别城市再生水风险因子筛选新方法,发现了病原微生物、重金属离子、苯系化合物、POPs等主要健康风险因子；针对病原微生物，探明了自由基破坏细胞核毒杀机理,创建了以Ag/AgCl和Fe2O3为杀菌剂的UV/H2O2/光催化杀菌工艺，并建立了杀菌后的废水毒性评价体系；针对再生水体中难降解有机污染物，研制了系列高活性、长寿命的阳极氧化TiO2纳米管阵列整体型光极与石墨烯基和类石墨烯光催化材料，并构建AOP去除COD反应单元，调控光生电对异向分离路径，提高对苯系化合物、POPs等有机污染物的矿化效率；针对重金属强化去除，首次发现离子印迹的“扫帚效应”，研发了系列扫帚状的离子印迹吸附材料、提高了吸附剂抗干扰能力及增强选择性吸附容量，建立“印迹-靶向”吸附剂去除新技术；并构建了光催化氧化／还原脱毒重金属离子工艺。针对再生水中氮磷超标的问题，研发了氧化锆基去除磷酸根新材料，诠释了零价铁／铜高选择性地催化还原硝态氮为氮气新机理，发现了低COD体系中，高耐受氨氮的微藻，揭示了在低COD状态下氨氮高效吸收机制，建立了菌藻协同处理稀土园区高氨氮废水新方法，构建了氨氮生物吸收去除、磷酸根吸附减排单元，实现氮磷零排放。针对城市再生水中健康风险因子的差异，构建了病原微生物UV/H2O2消毒模块、重金属靶向吸附去除模块、有机污染物光电催化高级氧化降解模块，氨氮生物吸收去除、磷酸根吸附减排模块，可组合搭建成MBR与上述五个模块优化组合的城市再生水深度处理工艺。研究工作推动了光催化技术、离子印迹吸附技术的规模化、工程化、实用化的进程，降低了再生水利用过程中的健康与生态风险，保障了再生水的水质安全，为我国城市再生水的水质安全保障技术提供了理论基础。