Comparison of using animal manure and sludge compost as biofilter filling material for off-gas control in aerobic composting

Biofiltration is an important method for composting off-gas treatment. Compost-based materials are widely used as the filling media for biofilter. To expand the application of compost from different composting materials in off-gas control for organic waste aerobic composting, the NH₃ removal efficiency, N₂O generation, and microbial communities of ammonia monooxygenase (amoA functional gene was selected) and nitrite reductase (nirS functional gene was selected) were investigated using the animal manure compost (AMC) and sludge compost (SC) as filling materials. AMC showed a higher NH₃ removal efficiency (average 82.9 ± 12.1 %) than SC (average 58.9 ± 21.9 %). Achieving stable NH₃ removal took longer with the AMC biofilter than with the SC biofilter. More N₂O was emitted from the AMC than from the SC. The ammonia-oxidizing bacteria (AOB) community composition in the AMC changed significantly after 30 days, whereas the denitrifying bacterial communities changed minimally. The AOB community structure in the SC was more stable than that in the AMC; however, the community compositions in the AMC and SC gradually converged with the extension of operation. These results indicate that the AMC is more suitable than the SC as biofilter filling material for NH₃ control. This study provides a significant reference for optimizing the application of compost-based biofilter off-gas control technology.