Integration of yeast cells flocculation with continuous ethanol fermentation using laboratory scale of integrated aerobic anaerobic baffled reactor

Shift of fossil fuels to biofuels, especially ethanol, is going on. On the other hand, the global pandemic has been encouraging the demand for ethanol to increase accompanied by rising its price. Consequently, ethanol is not competitive for fuels. Therefore, it should be an effort to lower the price including by increasing productivity of fermentation process due to the higher productivity the lower production cost. This study aims to make a higher productive fermentation method by integrating cells flocculation with continuous fermentation using a laboratory scale of the integrated aerobic anaerobic baffled reactor. The baffled reactor with a working volume of 10 L (consist of 2 compartments) was operated with molasses medium 30% w/w for 198 hours of incubation consisting start up and continuous operation. In the continuous part, the feeding of molasses medium 30% w/w was flowed at 0.5 L/h constantly, while flocculation processes were applied 7 times when the continuous process was going on. The samples were taken out periodically every 6 hours to measure parameters responses, i.e. the level of cell density, residual sugar, and ethanol produced. The continuous fermentation was stable running for 150 hours without significant deactivation. It processed 88 L of molasses medium 30% w/w or equal to 1.9 times the similar volume of the batch reactor, while the ethanol productivity was 4.05 g/L.h.