Improvement of ethanol production by extractive fed-batch fermentation in a drop column bioreactor

The use of fed-batch extractive fermentation can overcome inhibitory effects caused by the substrate and ethanol to the yeast cells, since it allows regulate the substrate concentration and remove the product as it is produced. The present study describes the modelling and experimental validation of ethanol production in fed-batch extractive fermentation with in situ ethanol removal by oleic acid in a non-conventional drop column bioreactor (DCB) operated under industrial conditions. The model developed using the hybrid Andrews-Levenspiel equation and ethanol distribution coefficient parameter (K_DE) provided an excellent description of the fed-batch extractive ethanol fermentation process with oleic acid. Furthermore, extractive fed-batch fermentation allowed the feed up to 306.6 kg m^-3 of substrate (total reducing sugars), with total ethanol concentration in extractive fermentation in the ranging 100.3-139.8 kg m^-3 (12.7-17.7 ºGL), 19.9-67.2% higher when compared with the conventional process without ethanol removal. Moreover, this process has the advantage of less effluent generated and energy consumption for ethanol recovery when compared to the conventional process.