Process Engineering of the Acetone-Ethanol-Butanol (ABE) Fermentation in a Linear and Feedback Loop Cascade of Continuous Stirred Tank Reactors: Experiments, Modeling and Optimization

The production of butanol, acetone and ethanol by Clostridium acetobutylicum is a biphasic fermentation process. In the first phase carbohydrate substrate metabolized to acetic butyric acid, in following second product spectrum shifted towards economically interesting solvents. Here we present cascade six continuous stirred tank reactors (CCSTR), which allows performing time dependent metabolic phases an acetone-butanol-ethanol (ABE) batch spatial domain. Experimental data steady states under four operating conditions—with variations pH bioreactor between 4.3 5.6 as well total dilution rate 0.042 h−1 0.092 h−1—were used optimize validate corresponding mathematical model. Beyond residence distribution representation substrate, biomass kinetics this model also includes differentiation cells states. Model simulations predict final concentration 8.2 g butanol L−1 productivity 0.75 CCSTR operated at pHbr1 D = h−1, while 31% are differentiated solventogenic state. Aiming enrichment solvent-producing cells, feedback loop was introduced into cascade, sending from later state process (bioreactor 4) back early stage 2). agreement with experimental observations, accurately predicted increase formation stages 2 3, resulting overall 0.76 for cascade. here presented validated will serve investigate further ABE strategies controlled switch.