Gas holdup, power consumption, and oxygen absorption coefficient in a stirred-tank fermentor under foam control

For a laboratory stirred-tank fermentor (STF) with foaming system of 0.5M sulfite solution containing an anionic soft detergent, the performing of a foam-breaking apparatus with a rotating disk (FARD)fitted to the STF was evaluated. The gas holdup in a mechanical foam-control system (MFS), i.e., the stirred-tank fermentor with the rotating disk foambreaker, was confirmed to be larger than that in a nonfoaming system (NS), i.e., the STF with an antifoam agent added. The agitation power in the mechanical foam control system was found to be smaller compared with the agitation power in the nonfoaming system, due to the increased gas holdup. Comparison of the oxygen absorption coefficient between the mechanical foam control system and the nonfoaming system in terms of the specific power input also demonstrated the superiority of the mechanical foam control system, not only in oxygen transfer performance but also in power input economy.