This study concerns on hybrid reactive adsorption approach of biogas upgrading using sustainable adsorbents (activated carbon, calcined eggshell, and carbide slag) to remove CO2, and H2S from biogas after anaerobic co-digestion of cow dung and sesame husk using Response Surface Methodology (RSM). The highest result from co-digestion was recorded for CH4 (69.07%), CO2 (29.03%), and H2S (1708 ppm) at a ratio of 50%:50%. The results suggested that RSM to increase the concentration of CH4 by parameter optimization involves the adsorption of H2S and CO2 on the surface of hybrid reactive adsorbents. The data from the optimization experiment on upgrading was analyzed and modeled using Design-Expert version 13 Box-Behnken Design (BBD) with three numeric factors: adsorbent particle size (45–750 μm), Gas flow rate (0.5–2.5 L/min), and calcination temperature (700–900°C) for the response of CH4, CO2, and H2S. Significance was then accepted at a 0.05 level of probability (P < 0.05). Analyzing the experimental trial data yielded highly statistically significant regression model equations with R2 = 99.81%, R2 = 99.81%, and R2 = 99.63% for CH4, CO2, and H2S, respectively. Consequently, the highest result has recorded CH4 content of 97.79% from 92.94%, CO2 2.18% from 6.64%, H2S 18.56ppm from 43.24ppm at the combination of actual parameters calcination temperature 800°C, adsorbent particle size 45 μm, and gas flow rate at 1.5 L/min resulted in the methane’s calorific (energy) value of 35.2044 MJ/m3. This study explores the effectiveness of a novel hybrid reaction adsorption system in biogas purification. The process demonstrates significant improvements in removing problematic impurities, resulting in biogas suitable for a wider range of energy applications.
Hagos et al. (Mon,) studied this question.