Decarbonizing Food Waste Treatment through Anaerobic Codigestion with Yard Waste: Energy, Engineering, Economic, and Environmental Aspects

This study presents the design and analysis of an anaerobic codigestion (AcD) system to replace the existing composting system for food waste (FW) and yard waste (YW) treatment on a university campus. By combination of kinetic models, anaerobic degradability analysis, cost analysis, and life cycle assessment (LCA), a comprehensive energy, engineering, economic, and environmental approach is applied to achieve FW decarbonization. The optimal AcD ratio of FW:YW (3:1) demonstrates a CH4 production rate of 38.2 ± 0.7 mL/g VS/day, with a biomethanation potential of 0.97 and sludge activity of 100%. The economic analysis reveals a discounted payback period of approximately 2.6 years over a 10 year project lifetime, demonstrating the feasibility and financial viability of the AcD system. Furthermore, the LCA comparison between AcD and composting shows a significant carbon emissions reduction of approximately 68% (∼146 kg CO2-eq/t-FW lower) for AcD, resulting in an annual reduction of 32 tonnes of CO2-eq if implemented for the total FW production (219 tonnes per year) on the campus. Lastly, the study proposes potential pathways for achieving carbon neutrality in decentralized AcD plants, providing directions for future research.