Reduction of Wastewater Discharge toward Second-Generation Acetone–Butanol–Ethanol Production: Broth Recycling by the Fermentation–Pervaporation Hybrid Process

Abstract In this work, in order to reduce the butanol fermentation wastewater (BFW) discharge and to address the difficulties in BFW treatment, a novel fermentation-pervaporation hybrid process was performed for broth recycling. After each batch of acetone-butanol-ethanol (ABE) fermentation, ABE in fermentation broth was ex situ separated by pervaporation. The retentate was used as the buffer and the solution for the following batches of enzymatic hydrolysis and fermentation, respectively. Results showed that there were little negative influences of the phenols and acids inhibitors on the fermentation performances using the recycled BFW. Benefits from the broth recycling process were obvious. After 4 cycles of BFW, ~86 % of the BFW discharge was saved, and above 94 % of ABE with concentrations of 42.5-50.2 g/L was recovered by pervaporation. Therefore, the novel process can effectively eliminate the obstacle of large BFW discharge in the ABE fermentation processes.