Biological conversion of CO₂ to CH₄ using hydrogenotrophic methanogen in a fixed bed reactor

Abstract

Abstract BACKGROUND: Biological conversion of CO 2 to useful carbonic compounds such as methane is a potentially attractive technology for reducing its concentration in the atmosphere. One of the advantages of this technology over chemical conversion is that it requires much lower energy for reduction of CO 2 . In this article, biological conversion of CO 2 to CH 4 using hydrogenotrophic methanogens was examined in a fixed bed reactor inoculated with anaerobic mixed culture from the anaerobic digestor of a sewage treatment plant. RESULTS: Methane formation commenced on the first day of operation of the fixed bed reactor. CO 2 fed to the reactor was reduced with H 2 by hydrogenotrophic methanogens. The feed ratio of CO 2 to H 2 is an important factor in determining the conversion rate of CO 2 . When the feed ratio is 4, methane is produced at the expected rate according to the chemical equation. The CO 2 conversion rate was 100% when the gas retention time was 3.8 h in the fixed bed reactor. CONCLUSIONS: The results show that the fixed bed reactor employing hydrogentrophic methanogens has the potential to be effective in converting CO 2 to CH 4 with a conversion rate of 100% at 3.8 h retention time. Copyright © 2012 Society of Chemical Industry