La production de biogaz par méthanisation de la panse des bovins : Effet d’addition de balles de riz

Abstract

This study investigates biogas production through the anaerobic digestion of bovine rumen content, using rice husks as a co-substrate, with the aim of optimizing methane yield and evaluating the energy potential of the process. The experiment was conducted using five batch digesters of 4 L capacity operated under mesophilic conditions (35–37 °C) over a period of 36 days. The digesters were fed with different proportions of substrate and co-substrate, resulting in carbon-to-nitrogen (C/N) ratios ranging from 20 to 30. Biogas production was monitored daily using the water displacement method, while biogas composition was determined by carbon dioxide (𝐶𝑂₂) absorption in a potassium hydroxide (𝐾𝑂𝐻) solution, allowing the estimation of methane (𝐶𝐻₄) content. The results showed that biogas production followed a typical sigmoidal pattern, characterized by a lag phase (days 1–3), an exponential phase (days 4–10), a stationary phase (days 11–25), and a decline phase (days 26–36). Among the tested digesters, D3 with a C/N ratio of 25 exhibited the best performance, producing a cumulative biogas volume of 21,471mL and methane volume of 15,357mL, corresponding to a methane yield of 71.5%. Digesters D5 (C/N = 30) and D4 (C/N = 27,5) showed moderate performance, while D1 and D2 (C/N = 21.6 and 20) yielded lower results. These findings confirm that C/N ratios in the range of 25–30 enhance microbial activity and methane production. These results demonstrate that anaerobic digestion of organic waste constitutes a viable source of renewable energy. At a larger scale, this process shows significant potential to contribute to electricity production and the energy recovery of waste. In conclusion, the co-digestion of bovine rumen content with rice straw significantly improves biogas and methane production, particularly at an optimal C/N ratio of around 25. This approach represents an effective and environmentally friendly solution for waste valorization and energy generation.