Investigation of the mechanisms for bioelectrochemical methane production
Summary
The methane producing microbial electrolysis cell (MEC) is a recently discovered
technology that is able to convert CO2 into methane using an energy source and
electrochemically active micro-organisms as catalyst. Previous lab scale studies have
shown reasonable methane production rates with high energy efficiencies for different
cathode potentials. However, for further improvement of the design of the MEC, the
exact processes that are occurring at the bio-cathode need to be unraveled. This study
describes the possible methane production routes in two MECs at different cathode
potentials. The results presented here suggest that mixed cultures are able to accept
electrons directly for methane formation and indirectly via the intermediates H2 and
acetate at a cathode potential of -0.7V. At this cathode potential, methane was
produced at production rates up to 7.6 ml CH4/L reactor per day with cathodic
electron efficiencies that reached up to 99%.