Model Development and Simulation of Anaerobic Digestion Process Using Aspen Plus

Abstract

Cleaner energy, particularly biogas, is urgently needed. Biogas is generated via anaerobic digestion (AD), decomposing organic materials without oxygen. AD simulation models are appreciated for their cost-effectiveness and predictive accuracy. This study creates a process model with Aspen Plus to simulate AD and biogas production. Investigations simulated municipal solid waste (MSW), animal manure (AM), and co-digestion feedstock, including hydrolysis equations for carbohydrates, proteins, and fats. MSW includes a water flow of 10°C and 1500 m³/day. The AM enters at 230.4 g/day, while water flows into the mixer at 2300 g/day. The biogas rates for MSW, AM, and co-digestion were 9775.663, 0.25, and 10024.98 m³/day, respectively. Increasing hydraulic retention time (HRT) boosts the biogas production rate. The carbohydrate effect increases biogas rates for MSW and co-digestion feedstock by 65% and 25%, respectively. Carbohydrate content increases from 35% to 55% for AM feedstock, with rising gas production and a linear decrease in methane output. With the increase in protein, the percentage of gas production increases in all cases. Although for MSW, the optimal conditions occurred between 16% and 20% of protein. Gas production drops with fat in MSW but rises in AM. A 50% increase in parameters shows co-digestion is more affected by protein.