Research On The Efficient Anaerobic Digestion Performance And Biogas Production Of Kitchen Waste

Kitchen waste is a solid waste which is generated from people’s daily diet. Kitchen waste as the main organic compound of urban house refuse, is mainly from schools, farmers market, all enterprises and institutions and food service industry. It has high moisture content, and easy to decay, acidification, which has caused a series of the environmental pollution problems. In Beijing, Shanghai, Shenzhen and other big city, the per capita output of kitchen waste has reached1kg.At present, the main treatment method to kitchen is energy oriented, which includs landfill, composting, incineration, feed processing, anaerobic digestion technology. Advantages of anaerobic fermentation technology is that it cannot only make waste reduction and efficient, can also produce organic fertilizer, generate clean energy biogas. Therefore, the processing method of anaerobic digestion is ideal. Kitchen waste of canteen in various districts of Beijing was chosen as sample, made a determination of characteristics. Results indicated that value of VS/TS remains81%-94%, and the composition changing without regularities. Inorganic salt, cellulose, starch, protein and lipid in the total content of five dry matter in the kitchen also was in70%above. Among them, the highest content was starch. The value of C/N remains10-20. The thermophilic and mesophilic anaerobic fermentation to kitchen waste was studied in the change of inoculums and moisture.Biogas potential of kitchen waste and the influence of added ratio of pyrolytic carbon on biogas production at different OLR were determined in this research. Great performance of kitchen waste in biogas production was observed. The Modified Gompertz model was applied in modeling methane production to describe and predict cumulative methane yield through the entire anaerobic digestion process. The results showed that biogas yield and methane yield reached the maximum value, were904.63and562.06mL·gVS-1. The maximum biodegradation rate was90.86%.Then, the optimization analysis of kitchen waste anaerobic digestion reaction conditions was researched, which included temperature, F/M, inoculums, moisture. The results showed that the optimization reaction condition was55℃, F/M=0.5, inoculum for chicken manure digestion liquid,90%of moisture.Semi-CSTR reactor was introduced to determine one phase anaerobic digestion performance of continuous feed kitchen waste. The reaction time was160days. The optimal volume biogas yield was936.27±5.92mL·L-1(2gVS·L-1·d-1). The average methane content was53.69%in the whole reaction process. The pH value remains stability at OLR (organic loading rate) by1gVS·L-1·d-1increased to2.5gVS·L-1·d-1. The pH value decreased rapidly at OLR increased to3.0gVS·L-1·d-1.