Optimization of Methane Production through Anaerobic Co-Digestion of Maize By-Products Using Mixture Design in Katiola, Côte d'Ivoire

Abstract

The environmental problems caused by energy are leading to the search for alternative, renewable energies. Côte d'Ivoire is part of this dynamic. Several biogas production projects have been launched in recent years. To improve production efficiency, it is important to work on optimising production parameters. This work aims to use a mixing plan to improve the production of methane by anaerobic co-digestion": the case of yellow bran (Xj), violet bran (Xv) and maize cobs (Xr). The methodology adopted started with the establishment of the constraints for each mass fraction required by the Expert 13 software. Eleven experimental runs were conducted and finally the mathematical and statistical analysis of the model was studied. The results revealed the following constraints: 0.25 < Xv < 0.625, 0.25 < Xj < 0.625, 0.125 < Xr < 0.5. The second-degree polynomial model was used. The regression coefficient is R² = 0.824 and the P-value is 0.625: these criteria confirm the descriptive quality of the model. The optimum biogas production increases from 167.2 m³/ton for purple bran to 2990.784 m³/ton for the mixture of yellow and purple bran and maize cobs. The optimum production was found to be 2033.73 m³/ton of methane (68% biogas), achieved by a formulation of the mass fractions (0.313 cob, 0.25 violet bran and 0.438 yellow bran). This combination produced energy of around 10,432.8 kWh/ton of biomass (methan energy content). This results show that the tested biomass is adapted for biogas production.