Holistic Scrubber for the Purification of Biogas from Community and Household Digesters

Anaerobic digestion has a dual role in waste management by producing biogas and mitigating the GHG emission from waste disposal sites. Failure in optimization of the various factors affecting anaerobic digestion will result in increased impurities affecting the quality and efficiency of the biogas generated. In the current scenario, a holistic scrubber will help in removing most impurities and increasing efficiency of biogas utilization. In the present study, a scrubber for biogas purification was fabricated and it consists of two separate units for the removal of H2S and CO2. It was evident that the charcoal was more efficient in removal of H2S than metallic scrap in all the bed sizes and the maximum removal rate for charcoal was observed at 100cm bed size with H2S concentration of 50 ppm at the outlet of scrubber, whereas it was 300 ppm for metallic scrap. Outcomes of biogas purification using different molar solutions of NaOH, KOH and Ca(OH)2 were studied . Results of Variation in molarities from 0.5M to 2.5M using three caustic solutions, resulted in CO2 removal at 34% to 5% for NaOH, 35% to 7% for KOH and 39% to 17% for Ca(OH)2. High caustic nature and absorption capacity of solutions made it appropriate to absorb carbon dioxide from biogas and keeping its impurities low.