污水生物处理过程氧化亚氮的形成机理及减量策略研究进展

Research progress on the mechanism of nitrous oxide formation and the mitigation strategies for nitrous oxide discharged during biological wastewater treatment

在“碳中和”的大背景下,污水生物处理过程中氧化亚氮(N_(2)O)的释放已经引起了人们的广泛关注,探究N_(2)O的产生机理和寻找缓解N_(2)O释放的策略也成为研究的热点.分析污水处理过程中能够产生N_(2)O的微生物及其特性,以及硝化过程和反硝化过程N_(2)O的产生机理,并从N_(2)O释放影响因素的角度总结缓解污水生物处理过程中N_(2)O释放的策略.随着对N_(2)O产生和消耗的研究不断深入,N_(2)O缓解释放的策略不再局限于工艺参数优化,微生物群落结构调控和完全反硝化过程强化也成为N_(2)O减排策略研究的热点.生物处理硝化过程不能消耗N_(2)O,只能通过减少N_(2)O产生的方式来降低N_(2)O的排放;与硝化不同,N_(2)O是反硝化过程的中间产物,这也就意味着反硝化过程能够消耗N_(2)O,因此反硝化过程作为N_(2)O的汇已经成为共识,如何有效促进反硝化过程是N_(2)O减量的重要途径.因此,可以通过改变微生物群落结构提高氧化亚氮还原酶(NOS)基因丰度来提升N_(2)O还原效率,添加生物炭调节电子分配实现完全反硝化过程,利用石墨烯促进反硝化酶活性提高N_(2)O的消耗等,以实现污水生物处理N_(2)O的减量排放.

The release of nitrous oxide(N_(2)O)during biological wastewater treatment has attracted widespread attention in the context of“carbon neutrality.”Understanding the mechanisms of N_(2)O generation and exploring new strategies for combating N_(2)O release have become research hotspots recently.This review surveys the microorganisms that are responsible for N_(2)O production in wastewater treatment and outlines the mechanism of N_(2)O production during nitrification and denitrification processes.In addition,the review summarizes strategies for N_(2)O release mitigation during wastewater biological treatment process from the perspective of factors influencing N_(2)O release.With advances in N_(2)O production and consumption,recent studies on N_(2)O mitigation strategies have focused on the regulation of microbial community structure and the enhancement of completion of denitrification processes,rather than process parameter optimization.Nitrification by biological treatments cannot consume N_(2)O,and the alleviation of N_(2)O release can only be accomplished by decreasing N_(2)O production.Unlike nitrification,N_(2)O is an intermediate product of denitrification,which means N_(2)O can be consumed during denitrification.Therefore,the utilization of denitrification processes as a sink for N_(2)O has become a consensus strategy,and thus,improvement in the efficiency of denitrification has become an important way to reduce N_(2)O.Methods to improve N_(2)O reduction include changing the microbial community structure to increase the abundance of the nitrous oxide reductase gene,the addition of biochar to regulate electron distribution for denitrification process completion,and the use of graphene to promote denitrification enzyme activity.These strategies can be employed to reduce N_(2)O emissions during biological wastewater treatment.