Extractive Fed-Batch Ethanol Fermentation with CO2 Stripping in a Bubble Column Bioreactor: Experiment and Modeling

Abstract

The ethanol accumulated in the broth during fermentation is the main component toxic to yeast, causing slower yeast growth and decreased ethanol production. One way of overcoming this inhibition effect is to use extractive fermentation, where the ethanol is removed from the broth during the fermentation process. The present work evaluates ethanol production by extractive fed-batch fermentation with CO2 stripping, under different conditions of substrate concentration in the must feed (CsF), vat filling time (Ft), and start time of ethanol stripping with CO2. First, the process kinetic parameters were estimated by modeling of conventional fed-batch fermentations (without stripping) in a 5 L bubble column bioreactor, with fitting of the model to experimental data. This procedure used a sucrose concentration of 180 g·L–1 in the must feed, temperature of 34.0 °C, and vat filling times of 3 and 5 h. Subsequently, extractive fed-batch ethanol fermentations were performed at 34.0 °C with a sucrose concentration o...