Combined addition of biochar and garbage enzyme improving the humification and succession of fungal community during sewage sludge composting.

The influences of combination of garbage enzyme and biochar on total organic carbon (TOC) degradation, humification and the fungal succession during sewage sludge (SS) composting were established. Results showed that the GE and BC + GE treatments significantly increased the enzyme activity of fluorescein diacetate hydrolase (FDA) and increased the TOC degradation rate by 9.8% and 21.9% relative to control. The excitation-emission matrix (EEM) combined with the percentage fluorescence response (Pi, n) also proved that the combination of BC and GE promoted fulvic acid-like and humic-like substances production, and thus increased humification. Furthermore, the combination of BC and GE effectively decreased the relative abundance of Unclassified_k_Fugni, while increased the abundance of Ascomycota and Basidiomycota compared with control. The four genera, Pseudeurotium, Talaromyces, Trichoderma, and Penicillium, were the main fungi for the humification. Comparatively, the combined of BC and GE showed the optimal performance for TOC degradation and humification during SS composting.