Addition of exogenous microbial agents increases hydrogen sulfide emissions during aerobic composting of kitchen...

Area of Science:

• Environmental Microbiology
• Waste Management
• Biogeochemical Cycles

Background:

• Hydrogen sulfide (H2S) emissions from compost are a significant environmental concern.
• The role of microbial agents (MA) in modulating H2S emissions remains controversial.
• Understanding microbial mechanisms is crucial for managing compost emissions.

Purpose of the Study:

• To investigate the effects of microbial agents (MA) on H2S emissions during kitchen waste composting.
• To elucidate the microbial mechanisms underlying MA's influence on H2S production.
• To identify key microbial players and pathways involved in H2S generation.

Main Methods:

• Composting of kitchen waste with and without MA addition.
• Analysis of H2S emission rates.
• Microbial community structure analysis using molecular techniques.
• Structural equation modeling to identify drivers of H2S emissions.
• Metagenomic analysis to assess functional gene abundance and pathways.

Main Results:

• MA addition significantly increased H2S emissions by 1.6–2.8 times.
• Microbial community structure was the dominant driver of H2S emissions.
• MA enhanced microbial participation in sulfur conversion and strengthened microbial-gene links.
• Abundance of keystone species and genes involved in sulfite and sulfate reduction (sat, asrA) increased.

Conclusions:

• Microbial agents promote sulfur conversion, leading to elevated H2S emissions in compost.
• MA reshape the compost microbiome, intensifying sulfur-reducing pathways.
• Microbial community structure and function are key regulators of H2S emissions in composting systems.