Sodium persulfate/manganese dioxide/ferrous sulfate synergistically enhance the ability of functional microorganisms to accelerate humification during composting

The acceleration of the composting process and improvement of the humification degree are critical objectives in kitchen waste (KW) composting. In this research, the synergistic effects of sodium persulfate, manganese dioxide, ferrous sulfate, and microbial agents on KW composting were systematically investigated with a focus on humus processes, bacterial community structure, and functional metabolism. The results demonstrated that the combined treatment achieved a remarkable cellulose degradation rate of 30.15%. Humus (HS) and humic acid (HA) contents increased significantly, reaching 178.75 and 58.92 mg·g−1, respectively. The combined treatment significantly increased the aromaticity of HA. Microbial community analyses revealed that the combined treatment enriched functional microorganisms, including Acetobacter and Pseudomonas while suppressing the population of Ascomycetes. Metabolic pathway analysis indicated enhanced humification-related activities in the combined treatment. Redundancy analysis (RDA) identified Pseudomonadota as the key phylum positively associated with HA biosynthesis. In summary, the combined treatment optimized composting efficiency by stimulating OM-degrading bacteria and enhancing the humification degree.