A novel electrolytic gas lift reactor for efficient microbial electrosynthesis of acetate from carbon dioxide

The low current density impedes the practical application of microbial electrosynthesis for CO2 fixation. Engineering the reactor design is an effective way to increase the current density, especially for H2-mediated microbial electrosynthesis reactors. The electrolytic bubble column microbial electrosynthesis reactor has shown great potential for scaling up, but the mixing and gas mass transfer still need to be enhanced to further increase the current density. Here, we introduced an inner draft tube to the bubble column to tackle the problem. The addition of draft tube resulted in a 76.6% increase in the volumetric mass transfer coefficient (kLa) of H2, a 40% increase in the maximum current density (337 A/m2) and a 72% increase in average acetate production rate (3.1 g/L/d). The computational fluid dynamics simulations showed that the addition of draft tube enhanced mixing efficiency by enabling a more ordered cyclic flow pattern and a more uniform gas/liquid distribution. These results indicate that the electro-bubble column reactor with draft tube holds great potential for industrial implementation.