N₂O Emission Characteristics and Mitigation Strategies in Membrane Aerated Biofilm Reactors for Wastewater Treatment

The membrane aerated biofilm reactor (MABR), as a novel wastewater treatment technology, has garnered extensive attention for its high nitrogen removal performance and reduced nitrous oxide (N₂O) emissions. In the context of conventional biological nitrogen removal process, N₂O is produced through four main pathways, including hydroxylamine oxidation, AOB denitrification, heterotrophic denitrification, and chemical reactions. Remarkably, the MABR exhibits a lower potential for N₂O emission compared to traditional aeration methods. This decrease is primarily due to its unique substrate counter-diffusion mechanism and bubbleless aeration, which mitigate N₂O production potential and emission level. This paper summarizes the pathways of N₂O generation and reduction in MABR systems, discusses the influencing factors and control strategies of N₂O generation and emission, and looks forward to the future research directions for N₂O emission management in MABRs, thereby highlighting the advantages of MABR in further engineering application in carbon emission reduction.