Enrichment in Methane Content in Biogas By External Voltage Supply

The increment in the methane content has a major role to broaden the application of biogas. Enhancement of the methane-generating metabolism of microorganisms known as methanogens is required to increase the methane production. Research has shown that methanogens can use supplied voltage to acquire the electrons for the production of methane from CO2. In this process, methanogens reduce CO2 to CH4 utilizing electrons from externally supplied voltage on integrating with anaerobic digestion. Microbial electrochemical cells (MEC) was developed employing biocompatible fibrous graphite electrodes. Cow manure was assessed for the anaerobic digestion combined with MEC. The objectives of the study were to use manure waste and to enrich methane in biogas even at low temperature condition. The biogas produced contains mainly methane, hydrogen sulphide and carbon dioxide. The maximum gas production was at 37oC. However, biogas could be produced at 18oC with supply of 2V external power. There was found 65 times increment in biogas production with external power supply at 18oC. Besides methanogens, two other bacterial species identified were Serratia liquefaciens and Zoballella taiwanensis respectively. Keywords: Methane, biogas, methanogens, voltage, anaerobic digestion, microbial ecology