Assessment of the biogas potential of a small-scale biodigester using ASPEN plus simulation

The increasing demand for sustainable energy and challenges in organic waste management in developing countries necessitate optimised biogas production systems. This study aims to evaluate the biogas generation potential of small-scale anaerobic digesters using kitchen waste, with a focus on the impact of feedstock composition (carbohydrates, lipids, and proteins) on methane yield, gas quality, and environmental benefits. Using ASPEN Plus V14 process simulation, three feedstock scenarios were modelled to predict methane (CH₄), carbon dioxide (CO₂), and hydrogen sulphide (H₂S) concentrations. Results revealed methane yields ranging from 40.68% to 54.4%, with protein-rich feedstock (Scenario 3) achieving the highest CH4 output, but at the expense of elevated H2S levels (2.38%). Scenario 1 (55% carbohydrates) demonstrated a methane concentration of 50.22%, translating to annual wood fuel savings of ~ 2,450 kg per household. The findings highlight the trade-offs between biogas yield and purity, emphasising the need for co-digestion strategies, gas scrubbing, and feedstock optimisation to enhance sustainability. This study underscores the role of small-scale digesters in reducing deforestation, mitigating greenhouse gas emissions, and improving energy access in developing countries.