Addition of exogenous microbial agents increases hydrogen sulfide emissions during aerobic composting of kitchen waste by improving bio-synergistic effects.

The effect of microbial agents (MA) on hydrogen sulfide (H2S) emissions in the compost is still a controversial issue. This study examined the effects and microbial mechanisms of MA on H2S emissions during the composting of kitchen waste. The results showed that MA addition can promote sulfur conversion to elevate H2S emissions by approximately 1.6 ∼ 2.8 times. Structural equations demonstrated that microbial community structure was the dominant driver on H2S emissions. Agents reshaped the compost microbiome, showing more microorganisms participated in sulfur conversion, and enhanced the connection between microorganisms and functional genes. The relative abundance of keystone species associated with H2S emissions increased after adding MA. Particularly, the sulfite and sulfate reduction processes were intensified, as evidenced by an increasing in the abundance and pathways cooperation of sat and asrA after MA addition. The outcome provides deeper insights into MA on regulating the mitigation of H2S emissions in compost.