Behavior of CO-water mass transfer coefficient in membrane sparger-integrated bubble column for synthesis gas fermentation

The gas-liquid mass transfer coefficient (k(L)a) of O-2 was investigated in a bubble column reactor (BCR) using a sintered gas filter (SF), ceramic membrane module (CMM), and hollow fiber membrane module (HFM), which have different ranges of gas supply areas. k(L)a was enhanced by increasing flow rate in all of the spargers. Different responses when changing the gas supply area were obtained depending on the sparger type. Average values of k(L)a that were 52 and 258% higher were obtained using a CMM-integrated BCR compared to SFs and HFMs. CO-water k(L)a was investigated using CMMs for application to gas fermentation. The CO-water k(L)a ranged from 28.3 to 113.7/h under the experimental conditions. Based on the experimental data from CO and O-2, a model to predict k(L)a was constructed for CMM-integrated BCRs. A dimensionless number indicating a gas supply area of the sparger was newly defined and included in the developed model.