Ethanol fermentation under dissolved carbon dioxide control

Dissolved carbon dioxide (dCO2) evolved from Saccharomyces cerevisiae was measured, controlled and used to drive repeated batch operation for ethanol fermentation. The experiments were conducted at four glucose feeds (150, 200, 250 and 300 g/1) under three dCO2 control levels (no control, 750 ppm and 1000 ppm). Results showed that the evolution patterns of dCO2 depend on the extent of glucose being utilized as well as the dCO2 control level. Repeated batch was successfully operated for four glucose feeds under dCO2 control. Controlling dCO2 level at 750 ppm, the self -cycling period for each repeated batch is 6.6 0.3, 7.3 0.2, 12.12 1.12, and 21.70 5.98 h, as glucose feed changes from 150, 200, 250 and 300 g/l, respectively. When dCO2 level increases, the self -cycling period increases as well.