Comparative study on aerobic compost performance, microbial communities and metabolic functions between human feces and cattle manure composting

Aerobic composting is an efficient method to treat animal manure, but comparative study in terms of composting between human feces with herbivore manure was very limited. The objective of this study was to explore the differences of composting performance, microbial communities as well as its metabolic functions between human feces (HF) and cattle manure (CM) composting using physicochemical analysis, 16S rRNA sequencing and PICRUSt function prediction. The results showed that HF treatment did not meet the compost maturity standard. Compared with CM treatment, the HF compost had the lower humus content and humic acid/fulvic acid ratio at the end of composting, indicating the lower humification degree under the same composting conditions. This was because the relative abundance of Actinobacteria and Proteobacteria treated with HF was lower than CM treatment during the composting process. In addition, PICRUSt analysis revealed that HF treatment was less abundant than CM treatment in genes related to metabolism, especially in Valine, leucine and isoleucine biosynthesis and C5-Branched dibasic acid metabolism, which were the dominant metabolic pathways belonging to amino acid and carbohydrate metabolism, respectively. Therefore, considering the excellent composting performance of cattle manure, it was recommended to add some cattle manure into raw materials during human manure composting. This study could provide valuable reference for the harmless treatment and resource utilization of human feces and cattle manure.