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

摘要

Simultaneous CO2 removal with renewable biofuel production can be achieved by methanogens through conversion of CO2 and H-2 into CH4. However, the low gas-liquid mass transfer (k(L)a) of H-2 limits the commercial application of this bioconversion. This study tested and compared the gas-liquid mass transfer of H-2 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-R/d and 136.10 mmol/L-R/d, along with a specific biomass growth rate of 0.15 d(-1) and 0.09 d(-1), 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 kLa of H-2 and thus enhance the bioconversion of H-2 and CO2 to CH4.