Improving biogas upgrading and liquid chemicals production simultaneously by a membrane biofilm reactor

In this study, a novel membrane biofilm reactor (MBfR) was developed for simultaneously biogas upgrading and liquid chemicals production. With external hydrogen supplied from inside of the gas permeable hollow fiber of the MBfR, CO₂ in biogas could be captured via a biological process as liquid chemicals and simultaneously producing high-purity methane. Continuous operation of MBfR further confirmed that higher solubilized hydrogen was favorably affecting acetate and ethanol titer and rate, and methane purity. Moreover, by retaining biomass on the outer surface of hollow fiber, the highest biogas purity (96.7%) and acetate and ethanol production rates (37.8 and 13.5 mmol L^-1d^-1) were achieved at a hydraulic retention time of 2.0 d. Meanwhile, the CO₂ and hydrogen conversion efficiency reached to the maximum of 93.8% and 98.1%, respectively. The findings obtained can pave a new way for efficient liquid chemical production and biogas upgrading with both economic and environmental benefits.