Converting kitchen waste into value-added fertilizer using thermophilic semi-continuous composting-biofiltration...

Thermophilic semi-continuous composting (TSC) is effective for kitchen waste (KW) treatment, but large amounts of NH₃-rich odorous gas are generated. This study proposes a TSC-biofiltration (BF) two-stage process. Compost from the front-end TSC was used as the packing material in the BF to remove NH₃ from the exhaust gas. The BF process was effective in removing up to 83.7 % of NH₃, and the NH₃ content was reduced to < 8 ppm. Seven days of BF improved the quality of the product from TSC by enhancing the germination index to 134.6 %, 36.5 % higher than that in the aerated-only group. Microbial community analysis revealed rapid proliferation and eventual dominance in the BF of members related to compost maturation and the nitrogen cycle from Actinobacteria, Proteobacteria, Chloroflexi, and Bacteroidetes. The results suggest that the TSC-BF two-stage process is effective in reducing NH₃ emissions from TSC and improving compost quality.