To achieve higher productivity in the ethanol fermentation system, a continuous ethanol fermentation has been investigated with the air-supplement in a packed-bed immobilized cell reactor system. Yeast cells were immobilized in the sodium alginate gel and the photocrosslinkable polymer gel. The immobilized cells were packed in a continuous column reactor and the feed medium was saturated by aeration. The study was focused on the effect of the aeration on the reactor productivity.
The result showed that, when the feed medium was fully saturated with oxygen through aeration into the medium reservoir, the maximum ethanol productivity in the reactor system was enhanced from 38 gEtOH/1-gel-hr to 55 g-EtOH/1-gel-hr at the residence time of 10-20 min. and the residence time for the 90% substrate conversion was decreased from 42 min. to 22 min. with sodium alginate gels. The similar results were also obtained with the photocrosslinkable resins. This behavior of air-supplied reactor system was considered due to the enhanced yeast growth and prolonged viability during the reactor operation by utilizable oxygen in the feed medium.