Feasibility study of food waste to energy\ud conversion through anaerobic digestion

The current work focuses on the feasibility of generating bio-energy from\ud food waste produced by California State University, Chico (Chico State), using\ud anaerobic digestion process. Attempts have been made to optimize various parameters\ud in order to determine the most favorable recipe for maximum biogas production from\ud the digested food waste. The biogas yields have been determined using batch anaerobic\ud thermophilic digestion tests at 50??2oC for a period of 27 days. The average Total Solid\ud (TS), Volatile Solid (VS), and Fixed Solids (FS) of the food waste were determined to\ud be 4.16 g/L, 3.19 g/L, and 0.5 g/L respectively. The Standard Error of Mean of the\ud mean for TS, VS, and FS was determined to be 6.3, 5.2, and 1.5 respectively while the\ud confidence intervals (+95%) were 6.35, 5.74, and 0.71 respectively. The total carbon\ud content of the food waste was between 19-20%. Methane production increased in the first week of incubation (up to day 8) in presence of 5 g, 10 g, 15 g, and 20 g of food\ud scraps. By day 8, 726 mg/L, 752 mg/L, 848 mg/L, and 935 mg/L of methane had been\ud generated from 5 g, 10 g, 15 g, and 20 g food scrap, respectively. The average methane\ud production over the 27 days of incubation from 5 g, 10 g, 15 g, and 20 g food scrap was\ud 682 mg/L, 688 mg/L, 68 6 mg/L, and 697 mg/L, respectively. The Standard Error of\ud Mean for methane production from 5 g, 10 g, 15 g, and 20 g food waste was determined\ud to be 24.1, 17.6, 19.6, and 22.7 respectively while the confidence intervals (+95%) were\ud 729.1, 722.2, 724.6, and 741.2 respectively. However, a characteristic oscillation was\ud observed in the rate of methane production, with decline in production in day 10\ud followed by an increase in the subsequent days of incubation. This may be due to the\ud presence of methylotroph population in the activated sludge, which uses methane as a\ud carbon source for their growth. The total biogas generated in the system over the\ud experimental period was the sum of methane and carbon dioxide. The concentrations of\ud both gases were determined through a Gas Chromatograph. Biogas produced from the\ud decomposition of food waste was a mixture of 76% methane and 24% carbon dioxide.CSU, Chic