Simulation of Optimal Biogas Production in Anaerobic Digestion Using Aspen Plus

The high demand for fossil fuels, in addition to the related environmental effects, are encouraging research into renewable energy production from biological resources and wastes. Anaerobic digestion is a low cost and environmentally acceptable way of producing biogas from biomass. This biogas can be utilised to generate electricity, heat systems, or in a combined heat and power system. Nonetheless, biogas generated by anaerobic digestion contains a significant amount of CO₂ and has a lower methane purity. The present research on biofuel generation using two stage digesters has yielded significant results in terms of boosting the biogas production rate and methane output. In this model, a total of 46 reactions were used. The hydrolysis reactions were based on the extent of the reaction, while the acidogenic, acetogenic, and methanogenic reactions were based on the kinetics. At thermophilic conditions, a two-stage digester was used in the simulation. The objective of this research was to use Aspen Plus to find the optimal feed flow rate and operating pressure to yield the maximum amount of pure methane. Sensitivity analysis was performed for different substrate concentrations in order to increase the methane percentage in the biogas by analyzing the impacts of hydrogen addition, Pressure, and Hydraulic Retentions Time.