Food waste management and the possibility of conversion of waste to electrical energy in Kuwait

Abstract

Food waste management poses a significant environmental challenge in Kuwait, where over 90% of food waste is disposed of in landfills, leading to greenhouse gas emissions, leachate contamination, and inefficient land use. This study investigates anaerobic digestion as a sustainable waste-to-energy strategy, focusing on the influence of inoculum source, substrate composition, and hydrogen addition on biogas production and methane yield. The primary objective is to evaluate how different inoculum types and process enhancements impact methane generation from mono- and co-digestion of locally abundant food waste materials, including date fruit, meat, rice, and Sidr fruit. Anaerobic digestion experiments were conducted using two inoculum sources: wastewater-derived and food waste-derived. When digesting date fruit alone, wastewater inoculum produced 594 litres of biogas per kilogram of volatile solids with 59% methane, compared to 562 litres and 50% methane using food waste inoculum. Co-digestion of date fruit with rice and meat achieved the highest methane yield of 661 litres per kilogram of volatile solids at 66% methane concentration, attributed to enhanced microbial synergy and nutrient balance. In comparison, Sidr fruit codigestion yielded 519 litres per kilogram with 67% methane, demonstrating high methane quality but a lower volumetric yield. This research is also the first to assess hydrogen injection in the anaerobic digestion of date fruit. Hydrogen addition at 0.67 millilitres per minute significantly increased methane production from 283 to 628 litres per kilogram of volatile solids, with methane concentration rising from 50.5% to 60%, highlighting the role of hydrogenotrophic methanogens. Overall, the findings demonstrate that inoculum type, substrate synergy, and hydrogen enrichment are critical parameters in optimising biogas output. This study contributes new insights into anaerobic digestion process design and offers a scalable framework for sustainable energy generation from food waste in Kuwait.