In situ extractive ethanol fermentation in a drop column bioreactor

BACKGROUND In conventional ethanol fermentation processes, the low ethanol content in the wine is due to inhibition of its production by the yeast cells. Extractive fermentation is an alternative process that can be used to overcome product inhibition by removing the ethanol from the fermentation broth. The present study describes the modeling and experimental validation of ethanol production in extractive batch fermentation, with in situ ethanol extraction by oleic acid, in a non-conventional drop column bioreactor (DCB) operated under industrial conditions. RESULTS A model was developed using the hybrid Andrews–Levenspiel equation and the ethanol distribution coefficient (KDE), which provided an excellent description of the extractive fermentation process with oleic acid. Furthermore, higher ethanol productivities were obtained in the extractive fermentations, with ethanol productivity of 11.27–12.98 kg m-3 h-1, 12.7–29.8% higher when compared with the conventional process without ethanol removal. This was especially evident for the best extractive fermentation, which finished around 2 h earlier than the conventional fermentation. CONCLUSION The DCB showed good performance for use in extractive fermentation with liquid–liquid extraction of the ethanol and this technique presented higher ethanol productivity compared with the conventional process. © 2017 Society of Chemical Industry