Effect of nano zero-valent iron, potassium persulphate, and biochar on maturity and gaseous emissions during multi-material co-composting

Aerobic composting technology is expected to achieve higher quality composts. This study investigated the effects of exogenous additives on compost maturity and gaseous emissions during co-composting of pig manure and kitchen waste using nano zero-valent iron (NI), potassium persulphate (PS), cornstalk biochar (CB) and pig manure biochar (PB) additives. The results showed that CB and PB reduced electrical conductivity (EC) and increased compost maturity. All additives reduced total greenhouse gas emissions, including methane (CH4), by 28.6–71.5%, while only PB addition reduced nitrous oxide (N2O) emissions by 13.3%. PS addition resulted in the lowest pH value, and ammonia (NH3) emissions decreased by 53.1%. NI reduced hydrogen sulfide emissions by 20.4%. Additionally, all additive reduced dimethyl sulfide (Me2S) emissions by 18.6–44.2%,while they increased dimethyl disulfide (Me2SS) emissions by 7.6–150.6%. Therefore, these additives, especially PS, which exhibited superior performance, can cooperate to reduce greenhouse gas and odors emissions during composting.