Abstract:
Biogas produced from anaerobic digestion of organic waste is one of the potential alternative biofuels and is economically feasible, which might benefit the future energy supply demands as well as contribute to a reduction of greenhouse gas emissions. Biogas is primarily composed of methane (CH4) and carbon dioxide (CO2) as the major constituents, with trace amounts of other components like water vapour, hydrogen sulphide (H2S), hydrogen (H2), and nitrogen (N2). The presence of H2S in biogas needs special attention for cooking, power generation, as well as upgrading to bio-methane due to its foul-smelling odor, corrosion, health issues, and environmental problems. Scrubbing of CO2 is also essential for the upgradation of biogas, which increases the calorific value of the treated gas and enhances its efficiency for being used as vehicular fuel and power generation. Among various purification technologies, the absorption and adsorption methods are found to be simple, cost-effective, and easy to operate for the removal of CO2 and H2S from decentralized biogas plants installed in rural areas. Generally, the use of different alkaline chemicals in the chemical absorption and adsorption processes is a common technique for the removal of CO2 and H2S from biogas. But, the problem arises in the disposal of the used chemicals due to their toxic and environmentally unfriendly nature.
