Excel Solver Aided Biogas Kinetics Computation for Varied Ratio Co-digestion of Cassava Peels with Chicken Manure

The co-digestion of cassava peels (CP) and chicken manure (CM) offers a sustainable approach to biogas production, but optimizing process conditions and kinetic modeling remains crucial for efficiency. This study employed Excel Solver to estimate kinetic parameters in the modified Gompertz and Cone models for three different CP:CM ratios (1:1, 1:3, and 3:1) under mesophilic conditions (ambient temperature) and a retention time of 40 days. Anaerobic digestion (AD) was conducted in 4 L batch digesters with a 2 L working volume. Results showed that the 1:3 CP:CM ratio produced the highest cumulative biogas yield (0.25 m³) from experiment, outperforming the other ratios (1:1 = 0.2384 m3 & 3:1 = 0.1576 m3). At the optimal ratio, the modified-Gompertz model exhibited a superior fit (R² = 0.9684) compared to the Cone model (R² = 0.7586), with lower SSE values (2.157 vs. 16.503, respectively), confirming its reliability in capturing microbial adaptation and substrate degradation dynamics. The estimated parameters—biogas production potential (BP = 0.2076 m³), maximum production rate (k = 0.0226 m³/day), and lag phase (λ = 3.4 days)—highlighted the significance of nitrogen balance in optimizing biogas yield. The kinetic study is essential for predicting biogas production trends, optimizing digester performance, and designing efficient biogas systems, while Excel Solver provided is a user-friendly tool for nonlinear regression, eliminating the need for specialized statistical software. This study reinforces the potential of kinetic modeling and computational optimization in enhancing AD processes, paving the way for improved waste-to-energy conversion.