Greenhouse Gas Emission and Reduction in Biological Treatment of Agricultural Organic Solid Wastes Toward Resource Recycling

Agricultural organic solid wastes (AOSW) are often accompanied by agricultural production, with large quantities, leading to resource waste and environmental impacts. Composting and anaerobic digestion (AD) are mainstream and recommended methods of AOSW disposal in China. This research conducts a review of the greenhouse gas (GHG) emissions of AOSW composting and AD methods, with consideration of advancements, challenges, limitations, and future directions. Composting’s biogenic GHG contributes 30–740 kg CO2-eq·t−1 DM, with feedstock and systems as main factors. AD’s biogenic GHG comes from 0–10% methane leakage (196.5–982.4 kg CO2-eq·t−1 DM) and digestate composting (276.6–1002.3 kg CO2-eq·t−1 DM). Non-biological GHG for both is 11.3–561.8 kg CO2-eq·t−1 DM. Process regulation cuts GHG by 13.9–55.8%, exogenous addition by 6.0–97.3%. This paper highlights and discusses AOSW biological treatment’s GHG emission and reduction strategy, supporting low-carbon resource recycling.