Membrane-covered aerobic composting mitigated nitrous oxide emission through improved micro-aerobic state and...

In this study, the variables related to nitrous oxide (N₂O) emissions and their interactions during membrane-covered aerobic composting (MCAC) and conventional aerobic composting were characterized at multiple scales. For the first time, it was quantified that the MCAC-created micro-positive pressure (50-500 Pa) significantly increased compost particles aerobic layer thickness by 24 %-27 % (P < 0.001). Pile-scale results demonstrated that MCAC decreased the abundance of key functional genes (nirS, nirK, cnorB, and nosZ) and microbes (norank_f__A4b, Halomonas, norank_f__norank_o__SBR1031, and norank_f__Xanthomonadaceae) associated with N₂O emissions (P < 0.001); MCAC significantly enhanced the microbial metabolic potential for carbohydrate-based, carboxylic acid-based, amino acid-based, lipid-based, organic phosphate-based, and amine-based carbon sources (P < 0.05). Interaction analysis suggested that the improved micro-aerobic state inhibited the N₂O generation pathway, while the increased microbial utilization of carbon facilitated the N₂O reduction pathway. Consequently, MCAC decreased N₂O emissions by 20 %-27 %. These findings offer valuable insights for optimizing MCAC strategies to mitigate N₂O emissions.