Viability of Food Waste to Biogas Energy Through Anaerobic Digestion

Abstract

This study was conducted on the feasibility of food waste for biogas production in Wolaita Sodo University, Ethiopia. The study aimed to investigate the potential of different food waste categories for biogas production through anaerobic digestion. A total of 40 representative food waste samples with 100 grams each were collected from four source-separated food waste categories based on the various food menus of the University. The collected food waste samples were tested for %TS, %TN, %TVS and %TC. Besides, laboratory-scale anaerobic digestions were carried out exhaustively for each food sample for 25 days at 35^oC. Thus, the proportion of CH₄ and CO₂ of the biogas produced from each food waste categories was also evaluated. The analysis was done using IBM SPSS Statistics 21. Results showed that %TN, %TS, %TVS and %TC were 1.62%, 30.75%, 29.29 % and 16.27%, respectively. Small C: N ratio (10:1) was scored. The ratio of VS: TS was very high (95%). The mean CH₄ proportion produced from ISV, RB, IML and MA were 61, 65, 63 and 63 respectively. However, the mean CO₂ proportion produced from ISV, RB, IML and MA were 22, 20.5, 15.5 and 16 respectively. Thus, the proportion of CH₄ produced 61-65% and high ratio of VS: TS showed the viability of all food waste categories to biogas energy production. However, the small C: N ratio which is an indicator for the resistance of anaerobic digestion implied in need of other organic wastes rich in carbon content to the reactor. In general, the food wastes generated from WSU students’ cafeteria are a promising feedstock for anaerobic digesters concerning biogas production.

Keywords: Food waste, Anaerobic digestion, C: N ratio, %CH₄, _%CO₂ and Biogas

DOI: 10.7176/JETP/10-4-01

Publication date:August 31^st 2020