Effect of inoculation methods on the composting efficiency of municipal solid wastes

► Four kinds of inoculation methods were applied during solid waste composting. ► Inoculation enhanced the degradation of aliphatics, proteins, and polysaccharides. ► Inoculation increased the molecular weight and humification degree of the composts. ► The inoculation microbes significantly improved composting progress and efficiency. ► Multi-stage inoculation best enhanced composting progress and efficiency. Four types of inoculation methods were studied during the composting of municipal solid wastes and dry grass (MSWG). The methods included a control group as well as initial-stage, two-stage, and multi-stage inoculations. Fulvic acids were extracted from the composting materials and characterized by spectroscopic techniques. The results showed that inoculation of microbes in MSWG enhanced the biodegradation of aliphatics, proteins, and polysaccharides. The inoculation also increased the molecular weight, humic- and fulvic-like compound content, as well as humification degree of the composting products. The inoculation of microbes in MSWG significantly improved composting process and efficiency. The improvement efficiency was in the order of initial-stage