Effects of fungal agents and biochar on odor emissions and microbial community dynamics during in-situ treatment of food waste

[Display omitted] •Fungal agents and biochar can alter nitrogen transformation and release.•Co-addition of fungal agents and biochar reduced NH3, H2S and VOCs emissions.•Co-addition of fungal agents and biochar affected the microbial community structure.•FAPROTAX and PICRUSt2 analyzed microbial functions to decipher the reduced gas emissions. The effects of the co-addition of fungal agents and biochar on physicochemical properties, odor emissions, microbial community structure, and metabolic functions were investigated during the in-situ treatment of food waste. The combined addition of fungal agents and biochar decreased cumulative NH3, H2S, and VOCs emissions by 69.37%, 67.50%, and 52.02%, respectively. The predominant phyla throughout the process were Firmicutes, Actinobacteria, Cyanobacteria, and Proteobacteria. Combined treatment significantly impacted the conversion and release of nitrogen from the perspective of the variation of nitrogen content between different forms. FAPROTAX analysis revealed that the combined application of fungal agents and biochar could effectively inhibit nitrite ammonification and reduce the emission of odorous gases. This work aims to clarify the combined effect of fungal agents and biochar on odor emission and provide a theoretical basis for developing an environmentally friendly in-situ efficient biological deodorization (IEBD) technology.