Modeling and simulation of biomass anaerobic digestion for high biogas yield and CO2 mineralization

Abstract

Bioenergy is one of several renewable energy options derived from biomass that can help satisfy our energy needs.  Anaerobic digestion is a viable method for producing bioenergy in the form of biogas from biomass. The anaerobic digestion process is challenged with low biogas recovery, and low-quality effluent or CO₂ emission, which contribute to environmental pollution and the carbon footprint in the atmosphere. Computational process modelling and simulation can provide realistic information for dealing with the technological challenges involved with anaerobic digestion. In this study, modeling and simulation of the simplified anaerobic digestion process were done using SuperPro Designer software fed with biomass feedstock containing carbohydrates, proteins, and fats, as well as yeast, at 37 °C mesophilic temperature. The anaerobic digestion process yielded 89.655% of CH₄ and 10.345% of CO₂ and confirmed that the carbohydrate feedstock produces more CH₄ composition in the biogas. Mineralization of CO₂ using MgO yielded 0.23% MgCO₃, consuming > 99% of the CO₂ produced during the anaerobic digestion process. Environmental impact assessment of the effluent discharge yielded 0.142 kg Slds/L volatile solid with 6.01% COD reduction per batch of the anaerobic digestion process in an anaerobic digester with 90% (1.925 kg/batch) feedstock dosage. The data indicate that single-batch effluent cannot be discharged into the environment, hence indicating the possible recycling for multiple anaerobic digestion processing. The results are a significant guide for the realistic scalable production of high-quality biogas for bioenergy application, CO₂ mineralization, and environmental remediation.