Thermophilic compost inoculating promoted the maturity and mature compost inoculating reduced the gaseous emissions during co-composting of kitchen waste and pig manure

This study investigated the effects of inoculating thermophilic and mature composts on maturity, gaseous emissions, and bacterial communities during the co-composting of kitchen waste and pig manure. Results showed that the temperature peaked on day 4 of the inoculation compost amendment, which was earlier than the control treatment on day 8. In particular, the GI of the inoculated thermophilic compost was higher (88.65%) than that of other treatments (GI≤61%) on day 35. The addition of the thermophilic compost promoted the enrichment of Bacillus and Planifilum, accelerated organic matter degradation, and enhanced maturity. Inoculation with mature compost reduced CH4 emissions by 50.66%, owing to the enrichment of methane-oxidizing bacteria (norank_f_Methylococcaceae). Furthermore, the mature compost decreased NH3 emissions by 36.16% through physical absorption and microbial activity (reducing NH4+ production). Inoculation with compost amendment increased N2O emissions owing to the enhanced denitrification of the nitrate reduction function. Overall, thermophilic compost addition enhanced the composting process and improved maturity, whereas mature compost addition was more effective in reducing gaseous emissions during the co-composting of kitchen waste and pig manure.