Biogas Production from Food Waste Using SiO₂ Nanocatalyst: Optimization, Kinetics, and Methane Yield Enhancement

Efficient valorization of food and market waste for renewable energy is critical for sustainable waste management. This study investigates the enhancement of biogas production from food waste using a SiO₂ nanocatalyst via anaerobic digestion, with a focus on process optimization and gas quality. Food waste, market waste, and cow dung were combined in a 2.5:2.5:1 ratio, and water was added at twice the slurry volume. The SiO₂ nanocatalyst, synthesized and characterized by UV-Vis, FTIR, SEM, and EDAX (particle size 10–90 nm), was added at an optimal concentration of 3% by weight. pH optimization revealed maximum biogas yield at the original substrate pH (4.5–7.0). Pilot-scale experiments showed that the nanocatalyst increased total biogas yield by 23.5% (1165 ml with catalyst vs. 891 ml without) over 21 days and reduced the process time by 5.38%. Gas composition analysis by GC-MS and NaOH absorption confirmed a significant improvement in methane content with the catalyst (59.85–60%) compared to the control (30–32%), while CO₂ content decreased accordingly. The nanocatalyst stimulated microbial activity, enhancing methanogenesis and overall conversion efficiency. The residual digestate was suitable for use as biofertilizer, supporting circular economy principles. These findings demonstrate that SiO₂ nanocatalysts can substantially improve both the rate and quality of biogas production from food waste, providing a scalable solution for waste-to-energy conversion and contributing to sustainable biomass valorization strategies.