[Effects of Exogenous Microorganism Inoculation on Efficiency and Bacterial Community Structure of Sludge Composting]

In this study, municipal sludge, sawdust, and mushroom residues were used as raw materials for composting, and thermophiles and white-rot fungi were added into the compost in stages. By measuring physicochemical factors, including temperature, pH value, organic matter, water-soluble organic carbon, moisture content, total nitrogen, NH₄⁺-N, NO₃^--N, and germination index during the composting process, the effect of exogenous bacteria inoculation on the efficiency of compost was determined. By means of high-throughput sequencing technology, the variation of bacterial community structure and the impact of exogenous bacteria inoculation on bacterial community structure during sludge composting were also investigated. The results showed that the inoculation extended the high temperature duration, decreased the nitrogen loss, and accelerated the decomposition and detoxification of the compost. During the entire period of composting, the structure of bacterial community changed significantly. There was low similarity of bacterial community structure among different stages of the same composting, but high similarity was observed in different composting of the same period. The inoculation of thermophilic bacteria improved the abundance of bacterial community and increased the proportions of dominant genera in thermophilic phase, but changed no species of dominant genera. Canonical correspondence analysis showed that pH had the highest influence on the structure of bacterial community and that temperature possessed positive correlation with nine genera.