Synthetic microbiome and biochar enhanced human feces aerobic mesophilic composting

Effective methods to enhance aerobic composting of human feces are essential for improving composting efficiency and mitigating nitrogen loss. In this study, the effects of a synthetic human feces microbiome (SHFM) and biochar on human feces aerobic composting were investigated. Compared with the control group, the composting system inoculated with 10 % SHFM and biochar demonstrated the highest removal efficiencies for total solids, organics and nitrogen retention rate, with the enhancements of 29.86 ± 0.72 %, 16.15 ± 1.19 %, and 9.82 ± 0.42 %, respectively. Microbiome analysis revealed that Bacillus and Streptococcus from SHFM successfully colonized in the human fecal composting system. Pseudomonas, Nonomuraea, and Rhizobium which could enhance organics removal and nitrogen retention were enriched in the samples inoculated with SHFM and biochar. Moreover, the inoculation of SHFM and biochar increased complexities and the number of keystone species in species co-occurrence networks, indicating the enhancement of network stability. These findings suggested that the synergistic effect of synthetic microbiome and biochar represented an ideal strategy for improving human feces aerobic composting.