“双碳”背景下，污水处理不仅要实现资源化，还要减少碳排放。为降低N₂O排放，中外学者对城镇污水厂N₂O排放开展了大量研究。首先，概述污水处理中硝化过程和反硝化过程都会产生N₂O，反应过程中产生N₂O机理与方式也存在差异，N₂O的产生量也会由于工艺不同而改变。其次，综述3种典型污水生物脱氮工艺：循环式活性污泥法（cyclic activated sludge system, CASS）工艺、厌氧氨氧化（anaerobic ammonium oxidation, ANAMMOX）工艺、亚硝化-厌氧氨氧化（nitrosation anaerobic ammonium oxidation, CANON）工艺，以及影响城镇污水厂N₂O排放量产生的4种因素：碳源、溶解氧浓度、温度、磁场强度。最后，总结目前研究尚存在的不足，并从温度影响条件、碳源种类、CANON工艺机理、N₂O回收利用4个方面进行展望。CANON工艺对于去除N₂O有较好的效果，但需注意，反应中PH过低使NH₂OH和HNO₂反应生成N₂O，从而削弱去除效果。

Under the background of "dual carbon", sewage treatment not only needs to achieve resource utilization, but also needs to reduce carbon emissions. To reduce N₂O emissions, scholars at home and abroad have conducted extensive research on N₂O emissions from urban sewage plants. Firstly, it was summarized that both nitrification and denitrification processes in wastewater treatment produce N₂O. The mechanism and mode of N₂O production during the reaction process also differ, and the amount of N₂O produced may vary depending on the process. Secondly, three typical biological denitrification processes for wastewater were reviewed: cyclic activated sludge system (CASS) process, anaerobic ammonium oxidation (ANAMMOX) process, and nitrosation anaerobic ammonium oxidation (CANON) process, as well as four factors affecting N₂O emissions from urban wastewater treatment plants: carbon source, dissolved oxygen concentration, temperature, and magnetic field strength. Finally, the shortcomings of current research were summarized and provided prospects from four aspects: temperature influencing conditions, carbon source types, CANON process mechanisms, and N₂O recovery and utilization. The CANON process is effective for removing N₂O, but it should be noted that a low pH in the reaction can cause NH₂OH and HNO₂ to react and produce N₂O, thereby weakening the removal effect.