Mitigating greenhouse gas emissions from composting systems: A systematic review of process modifications and additive strategies

Abstract

Composting is globally recognized as a sustainable method to manage & divert organic wastes away from landfills, yet it releases potent GHG emissions, primarily N2O and CH4 which are responsible for 80–95% of composting's overall climate impact on a CO₂-equivalent basis, with a GWP 265–298 & 28–30 times that of CO₂ over a 100-year time period. This review identifies process modification (PM) and additive strategies (AS) as the two primary intervention pathways. PM, enhanced aeration and optimized turning regimes suppress CH₄ by maintaining aerobic conditions, while membrane-covered systems achieve industrial-scale reductions of ~79–100% for CH₄ and ~ 45–60% for N₂O. Among additives, biochar reduces CH₄ by ~50–80% and N₂O by ~20–40% through improved porosity and microbial habitat enhancement. Mineral amendments, including zeolite and phosphate-based additives, further enhance N2 retention. Integrated approaches combining multiple strategies achieve synergistic emission reductions of ~38–84% relative to landfilling while improving compost nutrient quality. © 2026