Kinetic modeling and optimization of biogas production from food waste and cow manure co-digestion

• Optimum TS of 8 % identified in mono digestion of cow manure used as constant parameter in co-digestion. • Co-digestion of food waste and cow manure optimized by feedstock composition adjustment. • Food waste to cow manure TS based ratio of 6:2 resulted in maximum 325 ml/g VS biogas yield. • Four different predicting models evaluated and parametrically compared, modified Gompertz outperformed others. As global efforts to reduce reliance on fossil fuels and improve waste management practices intensify, the development of efficient biogas production methods offers a promising solution. This study addresses the urgent need for renewable energy and effective waste management by investigating biogas production from the anaerobic digestion of food waste and cow manure. Optimal conditions for mono-digestion of cow manure were identified at 8 % total solid in 38 °C. In co-digestion experiments, varying food waste ratios were tested, with a 6:2 ratio based on total solid achieving the highest biogas yield of 325 mL/g VS. The synergistic effects of co-digestion led to enhanced nutrient balance and biogas production, significantly outperforming mono-digestion. The experimental data were analyzed using first-order kinetics, modified Gompertz, modified logistic, and transference models, with the modified Gompertz model providing the best fit (R²=0.999). Results showed improved biogas production and higher rates of volatile solids and COD removal. This study focuses on maintaining a constant optimized total solids concentration for optimizing feedstock composition to enhance biogas production and compares four kinetic models on predicting performance, providing insights into anaerobic digestion system improvement. The study's limitations, such as the lack of post-optimization TS adjustments, absence of pH control, fixed temperature conditions, highlight areas for future work to provide more insights and improve co-digestion efficiency.