Bio-methanation Characteristics and Biogas Production Potential of Selected Food Processing Wastes

Abstract

Food-processing industries generate substantial quantities of biodegradable residues that require environmentally appropriate management. This study evaluated the bio-methanation characteristics and gas-production potential of nine selected food-processing wastes under laboratory conditions. The wastes were characterised for moisture content, total solids, volatile solids, pH, organic carbon, total nitrogen, and carbon-to-nitrogen ratio using standard analytical procedures. Laboratory-scale anaerobic digestion was conducted in 5 L polycarbonate digesters for two months, and cumulative gas production was measured by water displacement. Moisture content ranged from 67.82% in cooked food waste to 91.45% in gherkins waste, while total solids ranged from 8.60% to 42.18%. Volatile solids varied from 81.76% to 94.78%, and pH ranged from 4.52 to 7.76. The C:N ratio ranged from 18.41 to 36.54, with an average of 27.69. Papaya waste recorded the highest cumulative gas volume of 13,850 mL, followed by carrot, watermelon, and gherkins wastes. Nippattu waste produced the lowest cumulative volume of 6,250 mL. The findings demonstrate clear differences among the selected substrates and indicate that feedstock composition influences anaerobic degradation and cumulative gas production. However, the measured volumes represent total displaced gas rather than methane-specific yield. Further replicated studies with standardised loading and gas-composition analysis are required before process-scale application.