Comparison of Reactive Distillation and Dual Extraction Processes for the Separation of Acetone, Butanol, and Ethanol from Fermentation Broth

Two processes, reactive distillation (RD) and dual extraction (DE), were presented and compared for the separation and purification of acetone, butanol, and ethanol (ABE) from fermentation broth. Reactive distillation produces all the extraction solvents needed from the fermentation products, while dual extraction utilizes extremely effective but nonbiocompatible solvents in extraction. In this work, these processes were simulated using Aspen Plus. The sugars consumed in the ABE fermentation were produced using SO2–ethanol–water (SEW) pulping from lignocellulosic biomass. According to the simulations, DE was more energy efficient of these two processes with energy consumption of 4.97 and 6.12 MJ kg–1 for all products and butanol, respectively. RD consumed 11.02 and 15.98 MJ kg–1 for all products and butanol, respectively. According to the economic analysis, the total investment costs were very similar for both of the processes. The DE process, with its slightly higher sales revenue, proved to be a more economical option. The economic analysis also showed that 83.3% to 94.9% of the total operating costs were caused by the price of lignocellulosic material and its pretreatment. Therefore, significant advances have to be made in the pretreatment of lignocellulosic material for it to be a noteworthy option for production of fermentable sugars.