Methane enrichment on biogas generated from anaerobic digester using coconut shell-based activated carbon

This study evaluates methane enrichment on biogas generated from Anaerobic Digester (AD) through CO₂ adsorption process so that biogas can be used as fuel for vehicle engines, power plants, and natural gas substitutes. The experiment was observed by passing biogas synthesis (45% CH4 + 55% CO₂) and biogas from cattle manure ±59.7% CH₄, ± 37.1% CO₂ and ±3.2% other gases) in spontaneously pressurized adsorption column. In addition, observation of CO₂ adsorption capacity at various pressure and fixed temperature (27°C) was performed using pure CO₂ (±98%). Methane in biogas has been successfully purified to 92% at 0.5 L/min flowrate and 79.6 seconds retention time. The adsorbent will be saturated after gas flowing for 60 and 80 minutes for synthesis biogas and biogas from AD on the amount of adsorbent of 266 grams. A change of surface area of activated carbon (AC) after thermal regeneration at 160°C for 2 hours was 7.51% and regeneration efficiency was 67%. The adsorption process followed Freundlich isothermal. This process can be feasible alternative technology to meet the need for biogas with high levels of methane in small-scale AD.