基于零价铁的污水同步脱氮除磷及资源回用技术基础研究

Pollution of nitrate and phosphate in water is severe now in China. The main challenge for these wastewaters treatment is the lack of organic carbon source. A feasible way to remove nitrate and phosphate from organic-poor wastewaters is denitrification basing on zero-valent iron and phosphate precipitation basing on the produced ferrous iron from denitrification. Meanwhile the phosphate could be recovered as phosphate reacts with ferrous iron to form vivianite. However, denitrification basing on zero-valent iron usually produces ammonia/ammonium, and phosphate precipitation basing on ferrous iron always resulted in complex FeP compounds rather than vivianite. Thus up till now, less researches are available for simultaneous removal of nitrate and phosphate basing on zero-valent iron. In this project, electrochemical reaction system with double chambers is introduced to perform simultaneous removal of nitrate at cathode and phosphate at anode basing on zero-valent iron. At the cathode, denitrifiers who can utilize electrons transported from anode (made of zero-valent iron) will be enriched, the denitrification process will be analyzed, the denitrification mechanism will be revealed, summing up the above the technology of denitrification basing on zero-valent iron will be established. At the anode, the basic chemical reaction between phosphate and ferrous iron (produced by iron anode) will be explored, the process of phosphate removal will be analyzed, the characteristics and recovery of products will be studied, summing up the above the technology of phosphate removal basing on zero-valent iron will be established. Combining denitrification at cathode and phosphate removal at anode, a special reactor will be designed and performed, the efficiencies of nitrate removal, phosphate removal and resource recovery will be determined, the operation modes, nutritional conditions and environmental factors will be optimized, thus the high-efficiency simultaneous-removal of nitrate and phosphate meanwhile recovery of resources from wastewaters will be achieved. This technology not only pushes forward the development of nitrogen and phosphorous removal, but also promotes the resource recovery from wastewaters. It is with significant scientific and applicable values, thus it deserves the foundation and research.

我国水体氮磷污染严重，碳源不足日益成为限制该环境问题解决的瓶颈因子。以零价铁为电子供体还原硝酸盐，同时产生二价铁产物废水除磷，并回收高赋价值的蓝铁矿，不仅可突破低碳废水脱氮除磷瓶颈，且可回收磷资源，具有重要的研发价值。但传统零价铁反硝化脱氮不彻底（易产氨/铵），二价铁除磷产蓝铁矿过程难控制，因此基于零价铁同步脱氮除磷技术的研究迄今鲜见。本项目拟引入双室电化学反应体系，以此为平台，在阴极通过零价铁脱氮菌种富集、脱氮过程解析，探明生物脱氮机理，实现零价铁阴极生物脱氮；在阳极通过亚铁除磷化学反应探究、除磷过程解析，获得蓝铁矿除磷产物，实现零价铁阳极除磷，并回收磷资源；耦合碳阴极脱氮和铁阳极除磷，研发并运试联合装置，探明工艺运行性能，完成基于零价铁的高效同步脱氮除磷及资源回用技术基础研究。本项目不仅可推动我国水体氮磷污染新技术的发展，还可提升污水治理过程的资源化水平，兼具科学意义和实用价值。

碳源不足已成为限制废水脱氮的瓶颈因子，寻求新型自养脱氮技术迫在眉睫；“磷污染严重”和“磷资源匮乏”是当今世界面临的两大“磷”难题，磷回收是解决这两大难题的必选之路；“双碳”政策下，含氮、磷废水的高效、低耗、减碳处理是关键。有鉴于此，本项目提出基于燃料电池系统的同步脱氮除磷及资源、能源回收技术。项目实施以来，分步实现了碳阴极生物脱氮、铁阳极化学除磷和同步脱氮除磷。在碳阴极生物脱氮方面，采用铁阳极和生物阴极，实现了废水自养脱氮和电能输出，探明了生物自养脱氮机理，解析了生物脱氮过程，同时采用实际废水验证了该技术的可操作性、稳定性和经济性；在铁阳极化学除磷方面，采用铁-空气燃料电池体系，实现了废水高效除磷和磷资源回收、电能回收，探明了铁阳极除磷过程，揭示了磷回收产物蓝铁矿的形成机制，同时采用实际废水验证了该技术的高效性、稳定性和经济性；在同步脱氮除磷方面，采用铁阳极和生物阴极，实现了废水的同步脱氮除磷和磷资源、电能的回收，探明了该技术的最佳运行工艺条件，验证了该技术的长期运行稳定性，为今后该技术在实际废水中的应用奠定了基础。本项目的研究可为“双碳”背景下含氮磷废水的处理、处置提供新思路、新方法。围绕上述研究，本项目发表SCI论文6篇，EI论文1篇；申请国家发明专利6项，已获权1项；作大会报告1次。