固相碳源-纳米铁协同强化水平潜流人工湿地修复低C/N地表水机制

At present, the organic pollution situations of water environment are under control in China, but the pollution from nitrogen is becoming an increasingly serious problem, the treatment of contaminated surface water with low C:N molar ratio appears to be a new challenge. On the one hand, the traditional biological removal of nitrogen technology relies on organic source level, on the other hand, the new biological removal of nitrogen technology is too complex and difficulty to carry out on a large scale. It lead to the serious nitrogen pollution situation. . The horizontal subsurface constructed wetlands learning from nature possesses by physical-chemical-biological mechanism treating water. Through filtration, adsorption, volatization, nitration-denitrification and assimilation processes, the horizontal subsurface constructed wetlands have higher efficiency nitrogen removal than the traditional biological technologies. Even so, the nitrogen removal mechanism in horizontal subsurface constructed wetlands is still heterotrophic denitrification by microorganism, the effect of denitrification is also controled by organic carbon source level in the water.. This solid phase organic-carbon source and nano zero calent iron in horizontal subsurface constructed wetlands have synergetic denitrification effcets on the nitrogen removal from water. By solid phase organic-carbon source and nano zero calent iron, the heterotrophic denitrification, chemical denitrification, Nitrate Anaerobic Ferrous-Oxidizing，iron autotrophic denitrification can happen simultaneously, which strengthens the nitrogen removal from wastewater in the anaerobic zone of horizontal subsurface constructed wetlands.. Through denitrification batch experiment on solid phase organic-carbon source, nano zero valent iron, and both of them, we try to disclose the synergetic denitrification effect between solid phase organic-carbon source and nano zero valent iron. During the process of nitrogen removal from low C/N surface water by horizontal subsurface flow constructed wetlands, we will analyze systematically the forms of organic carbon source, ferric salt and nitrogen, and study the denitrification potentials and the microbial community structures. By which, we try to disclose the synergetic denitrification effects between solid phase organic-carbon source and nano zero valent iron. Further, the key factors affecting the synergetic denitrification effects will be explored. The research project will afford technological reserve and scientific basis for the treatment of contaminated surface water with low C/N molar ration.

当前我国水环境有机污染的总体趋势得到了遏制，氮污染上升为主要的水环境问题。传统生物脱氮存在依赖有机碳源的技术瓶颈,因此低C/N地表水的修复成为一个重要的课题。人工湿地通过过滤、吸附、挥发、硝化-反硝化、生物同化等过程具有更好的脱氮禀赋，但作为其脱氮主要过程的异养反硝化仍受到C/N制约。本课题将缓释固相碳源与纳米铁盐联合用于水平潜流人工湿地（HSSFCWs），协同发挥异养反硝化、化学反硝化、厌氧铁氧化等优势；利用HSSFCWs中自然存在的氧化-还原分区，强化其脱氮禀赋。通过对固相碳源、纳米铁盐及二者联合反硝化批试验，揭示二者的协同反硝化效应。通过HSSFCWs对低C/N比地表水的铁碳协同脱氮过程中铁盐、固相碳源、氮素的形态转化，以及反硝化势、微生物群落结构特征分析，阐明协同反硝化机制。进一步地探索影响HSSFCWs铁碳协同反硝化的关键因素，为低C/N比地表水的生态修复提供技术储备和科学依据。

当前我国水环境有机污染的总体趋势得到了遏制，氮污染上升为主要的水环境问题。传统生物脱氮存在依赖有机碳源的技术瓶颈，因此低C/N地表水的修复成为一个重要的课题。人工湿地通过过滤、吸附、挥发、硝化-反硝化、生物同化等过程具有更好的脱氮禀赋，但作为其脱氮主要过程的异养反硝化仍受到C/N制约。. 本课题将缓释固相碳源与纳米铁盐联合用于人工湿地，协同发挥异养反硝化、化学反硝化、铁自养反硝化等优势。主要研究内容为：筛选适合于人工湿地的固相碳源、富铁基质，研究铁碳协同反硝化的相关机制，探索关键影响因素和关键参数，提供铁碳协同反硝化人工湿地构建技术原型。. 主要结果及关键数据为：1）揭示了人工湿地中固相碳源-纳米铁盐协同反硝化效应。固相碳源-纳米铁协同反硝化的机制主要是异养反硝化+自养反硝化（铁自养+氢自养）。其协同自养反硝化效率符合一级动力学过程。2）阐明了人工湿地中固相碳源-纳米铁盐协同反硝化的主次关系。自养反硝化伴随异养反硝化过程发生，仅自养反硝化过程的生化脱氮效率很低，在异养反硝化过程中协同自养反硝化才能显著提升脱氮效率。3）探索了人工湿地中固相碳源-纳米铁盐协同反硝化的关键影响因素及其关键技术参数。主要影响因素仍为碳源水平（C/N=3左右时，自养反硝化效率显著提升）、溶解氧水平（DO小于0.5反硝化效果较好，DO大于2会显著影响反硝化）、停留时间（自养/异养协同条件下，HRT可缩短到6h仍能够获得预期的脱氮效果）。. 科学意义和工程价值：人工湿地中铁碳协同反硝化效应和机制，对于构建更为高效的人工湿地，克服普遍的水体（污水）低C/N比现象具有重要科学价值。本课题提出的技术原型在农村生活污水的生态化处理、城镇/农村黑臭水体的旁路生态修复、海绵城市建设中低影响开发（LID）设施的构建以及弄田生态沟渠建设等方面具有重要价值。