Enhanced bioconversion of hydrogen and carbon dioxide to methane using a micro-nano sparger system: mass balance and energy consumption.

Simultaneous CO removal with renewable biofuel production can be achieved by methanogens through conversion of CO and H into CH. However, the low gas-liquid mass transfer ( ) of H limits the commercial application of this bioconversion. This study tested and compared the gas-liquid mass transfer of H by using two stirred tank reactors (STRs) equipped with a micro-nano sparger (MNS) and common micro sparger (CMS), respectively. MNS was found to display superiority to CMS in methane production with the maximum methane evolution rate (MER) of 171.40 mmol/L/d and 136.10 mmol/L/d, along with a specific biomass growth rate of 0.15 d and 0.09 d, respectively. Energy analysis indicated that the energy-productivity ratio for MNS was higher than that for CMS. This work suggests that MNS can be used as an applicable resolution to the limited of H and thus enhance the bioconversion of H and CO to CH.