Pathways, influencing factors and mitigation strategies for N2O emissions in wastewater biochemical treatment

Abstract:

Wastewater treatment is a significant contributor to greenhouse gas emissions, and the generation and emission of nitrous oxide (N₂O) in wastewater biochemical treatment have become a hot research topic. The production mechanism of N₂O generation is complex, and emission characteristics vary widely depending on the processes and operating conditions. While numerous studies have investigated N₂O generation and emission in wastewater biochemical treatment, there is a lack of research on N₂O emission reduction strategies based on the analysis of N₂O generation pathways. This paper systematically discusses the primary pathways of N₂O production in wastewater biochemical treatment process, including NH₂OH oxidation, nitrifier denitrification, heterotrophic denitrification, and abiotic pathways. The factors influencing N₂O production are described, including wastewater characteristics such as carbon source, nitrogen source, salinity, process parameters such as dissolved oxygen, reflux ratio, and the distribution of microbial communities. This paper summarizes corresponding mitigation strategies, highlighting the effective reduction of N₂O production and emission through process optimization, coupling different biochemical processes, and enriching microbial communities with low N₂O production levels. Current research challenges and future development directions are assessed, emphasizing that model construction remains an effective method to study N₂O production and emission biochemical treatment of wastewater, with broad prospect in N₂O recovery research.