Optimizing Biogas Production from Food Waste and Cow Dung: Impact of Mixing Ratios

Abstract

Optimizing biogas production from organic waste is crucial for sustainable energy and waste management. This study explores the optimal mixing ratio of food waste (FW) and cow dung (CD) in anaerobic digestion (AD) to enhance biogas yield. The 70:30 (w/w) FW and CD ratio achieved the highest biogas yield of 266.4 ± 1.55 mL CH₄/g volatile solids (VS) at 32 °C. Both the modified Gompertz (R² = 0.99) and Logistic Function models (R² = 0.99) effectively predicted biogas yields, confirming the robustness of this ratio. Fourier-transform infrared spectroscopy (FTIR) analysis indicated significant solubilization of cellulose and lignin, enhancing biogas production. This 70:30 ratio maintained process stability with low volatile fatty acid (VFA) and ammonia levels. The biogas production rate (R_m) ranged from 12.0 to 12.5 mL CH₄ with a 7.27-day lag phase, shorter than reported in previous studies. An integrated purification process efficiently removed gaseous pollutants and moisture, increasing methane content by 75%. This enhanced both the yield and quality of the biogas, making it more suitable for energy applications. The study highlights a commercially viable approach for sustainable biogas production, with significant environmental and economic benefits. The optimized co-digestion and purification process offer a scalable solution for renewable energy generation and effective organic waste management.