Methane formation from food waste by anaerobic digestion

Abstract

Anaerobic digestion has become a promising technology in waste management by converting an organic waste into biogas. From the present study, the optimum food to microorganism ratio (F/M) in anaerobic biodegradation has been evaluated. Also, using the optimum F/M ratio, the batch test study was conducted in different phases and under different temperature conditions for anaerobic digestion of food waste. The data obtained from the study has been used to calculate the methane generation rate constant (k) and measurement of biochemical methane potential (BMP) in anaerobic biodegradation. During anaerobic digestion, food waste (with total solids content of 15–30 %) was loaded with the inoculum (seed sludge with total solids content of 10 %) in the serum bottles (working volume 400 mL) and was incubated under mesophilic temperature conditions of 30 ± 2 °C, thermophilic temperature condition of 50 ± 2 °C, and under psychrophilic condition of 15 ± 2 °C for 40, 30, and 60 days respectively, at F/M ratio of 0.75. Also, maximum methane production of 0.88, 0.62, and 0.73 L CH4/g chemical oxygen demand (COD) was found under mesophilic, thermophilic, and psychrophilic conditions, respectively. At this maximum biogas production, the rate constant (k) was measured as 0.18, 0.23, and 0.10 days−1, respectively. Also, the BMP was measured as 84, 74, and 70 % at mesophilic, thermophilic, and psychrophilic conditions for 40, 30, and 60 days, respectively. In this study, the maximum biogas production was obtained at mesophilic conditions at food to microorganism ratio 0.75.