Anaerobic co-digestion: a sustainable approach to food processing organic waste management

Anaerobic digestion is a promising technology to control pollution and recover energy from organic matter. In this study, batch experiments were conducted to investigate methane yields of seven organic wastes from a food processing company and dairy manure (DM) from a tie-stall barn having two straw lengths (2 cm and 10 cm) at 52 °C. This was followed by anaerobic co-digestion of all organic wastes with DM in bench experiments. The results indicated that the highest methane yield was observed in lipid-rich waste (basil sauce, 0.47 L/gVS) followed by carbohydrate-rich wastes (pumpkin processing residue, 0.21 L/gVS); the lowest yield was obtained from tomato leaves and stems (0.09 L/gVS). Furthermore, the methane yield from DM was about 0.18 L/gVS, irrespective of the straw length. Anaerobic co-digestion of food processing residues with DM demonstrated a 41% increase in methane yield (0.24 L/gVS), as compared to DM alone (0.17 L/gVS), while the milling of both organic wastes and DM did not affect methane yields. Thus, integration of anaerobic co-digestion in food processing residue management is a sustainable approach that guarantees a closed-loop flowing economy and makes food processing environmentally friendly.