[Physico-chemical and microbial properties in thermophilic composting processes of different biological solid wastes]

Characterization on the physico-chemical and microbial properties were carried out in thermophilic composting processes of 3 different biological solid wastes: manure, garbage and sludge. pH increased to above 8 and C/N ratio decreased during the process. The effect of different bulking agents on the composting process is smaller compared to different raw materials. Among the 3 different materials, garbage composting shows highest composting activity, and the mass reduction rate is 47.2%-56.8% after 14 days. Quinone content, representative of microbial biomass, increases to 359.7-472.3 mol x kg(-1) at the late composting period. However quinone diversity index only increases to 6.1-6.7, suggesting lower microbial diversity. The composting activity of cattle manure is only high at initial period and then decreases. The quinone content is high at middle period of cattle manure composting with the value of 36.3-117.0 molx kg(-1). DQ is 10.3-12.8 at initial, and increases to 18.1-22.7 during cattle manure composting. The properties of sludge composting fall in the range between cattle manure and garbage. It is suggested that the differences of the composting processes are mainly caused by organic component level in different raw materials. Suggestions on the control of composting process are also proposed based on this study.