Biogas production from malt bagasse from craft beer industry: kinetic modeling and process simulation

In this work, biogas was synthesized from malt enriched-craft beer bagasse with the objective to generate clean energy. Thus, a kinetic model based on thermodynamic parameters was proposed to represent the process with coefficient determination (R²) of 0.82. A bench-top biodigester of 2.0 × 10^-3 m³ was built in glass, and equipped with sensors to measure pressure, temperature, and methane concentration. The inoculum selected for the anaerobic digestion was the granular sludge, and malt bagasse was used as substrate. Data were fitted to a pseudo-first-order model for the formation of methane gas using the Arrehnius equation as basis. For the simulations of biogas production, the Aspen Plus™ software was used. Results from 2³ factorial design experiments evidenced that equipment was efficient, and the craft beer bagasse showed great biogas production, with nearly 95% of methane yield. The temperature was the variable that showed most influence in the process. Moreover, the system has a potential for the generation of 10.1 kWh of clean energy. Kinetic constant rate for methane production was 5.42 × 10^-7 s^-1 and activation energy 8.25 kJ mol^-1. A statistical analysis using a math software was performed and evidenced that the temperature played a major role in the biomethane conversion.

The online version contains supplementary material available at 10.1007/s10163-023-01715-7.