Stratified aeration supplied an effective way for ammonia and greenhouse gas mitigation in composting

Composting is the most common approach for animal manure disposal, converting it into valuable organic fertilizer. Supplementary forced aeration has been proved can accelerating composting process. However, improper aeration from the bottom of composting biomass may lead to the inhomogeneous distribution of moisture and oxygen content, also blow ammonia (NH₃) and greenhouse gas to the atmosphere. Here, stratified continuous and alternate aeration strategies were applied to investigate the potential effect of optimized aeration method on composting efficiency, NH₃ and greenhouse gas emissions. Traditional aeration from bottom with the same total flowrate was set up for comparison. Both stratified continuous and alternate aeration could significantly increase the temperature and oxygen content in composting biomass in the upper layer that increased the degradation rate of organic matter by 74.4 % and 92.1 %, respectively. The seed germination index of the upper materials in the treatments with stratified continuous and alternate aeration were increased by 15.3 % and 33.4 %, respectively, comparing with traditional bottom aeration. Stratified continuous aeration strategy performed obviously benefit on NH₃ and nitrous oxide (N 2 O) mitigation which were 30.6 % and 27.7 % less than gaseous emitted from traditional bottom aeration. These findings indicate that stratified gas supply technology can accelerate the composting process and reduce NH₃ and N₂O emissions, making it a promising practical composting technique. • Stratified aeration improves the oxygen utilization in composting. • Alternate aeration promotes high temperature duration and material degradation. • Stratified continuous aeration reduced NH₃ emissions by 30.6 % and N₂O emissions by 27 %. • Inhibition of denitrification due to oxygen supply reduces N₂O emissions.