Cationic surfactant as methane–water mass transfer enhancer for the fermentation of Methylosinus trichosporium OB3b

[Display omitted] In this paper, we conducted an investigation into the use of bubbles modified with cationic surfactants in bubble coalescence inhibition and enhancement of methane-water volumetric mass transfer rate. Various cationic surfactants including hexyltrimethylammonium bromide (HTAB), octyltrimethylammonium bromide (OTAB), dodecyltrimethylammonium bromide (DTAB), and hexadecyltrimethylammonium bromide (HDTAB) were added to aqueous solution and the methane-water volumetric mass transfer coefficient (kLa) values were determined for each of the solutions. Enhancement of methane-water kLa was observed from 14h−1 to 69h−1, depending on the cationic surfactant type and concentration. Enhanced methane-water kLa in aqueous solution by addition of cationic surfactants was employed for the fermentation of methanotroph (Methylosinus trichosporium OB3b), and cell growth rate and maximum optical density was increased by 391% and 498%, respectively.