Characterization of Kitchen Waste as a Feedstock for Biogas Generation by Thermophilic Anaerobic Digestion

Abstract

Kitchen waste collected from the University Cafeteria was collected, mixed, analysed and used for production of Biogas under thermophilic anaerobic digestion. The samples were collected for two periods of about 13 weeks in different weather conditions. The analyses were arranged for both cases separately. The characterization of so-called non-source waste material revealed that the average MC, TS, and VS for daily week-long samples were 85.5%, 14.5%, and 88.2%, respectively, with standard deviations of 5.5%, 5.5%, and 4.6%, respectively. The average MC, TS, and VS for a twelve-week-long weekly sampling were 85.7%, 14.3%, and 87.5%, respectively, with standard deviations of 2.3%, 2.3%, and 1.9%, respectively. The C/N ratio for selected samples varied in the range 19.5-28.7 with an average C/N ratio of 23.3. Overall variability and consistency of collected kitchen waste was analyzed by ANOVA. Biogas was generated in a bench scale setup from the waste material for different TS concentrations. The analysis of the leftover material after anaerobic digestion indicated that 90% of organic material can be degraded within a period of 3 weeks at initial TS concentrations of 8% and lower. This observation supports the use of kitchen waste for thermophilic anaerobic digestion and biogas generation.