Reusing the acetone-butanol-ethanol separated broth as the lignocellulose pretreatment liquor for fresh corn stalk biorefinery

In this study, fresh corn stalk was used as the feedstock for the production of bio-butanol via acetonebutanol-ethanol (ABE) fermentation, in which process the wastewater from the first stage sugar containing juice fermentation was recycled by ex situ pervaporation and reused as the pulping liquor of the residual corn stalk bagasse (CSB), affording to effective ABE production in the subsequential second stage fermentation process. Results indicated that the juice fermentation wastewater could effectively depolymerize the CSB. Under optimized conditions of the pulping process (180 degrees C and 10% (w/v) of biomass loading), 32.45 +/- 0.85 g/L of total monomer sugars was obtained in CSB enzymatic hydrolysate, which can be directly used as the substrate for the second-stage cellulosic ABE production. Semi-simultaneous saccharification and fermentation (S-SSF) was carried out using the CSB pulps, so that improving the cellulosic ABE production. 10.94 +/- 0.65 g/L of ABE concentration with 0.18 +/- 0.01 g/L h of productivity were realized. After hybrid the first-stage juice fermentation and the second-stage CSB biotransformation, total 54.07 +/- 1.25 g (ABE) can be produced from 1 kg of fresh corn stalk. The alternative process showed great significance in reduction of the wastewater discharge and ensuring high pulping performances. (c) 2022 Published by Elsevier Ltd.

Automated summary

In this study, fresh corn stalk was used as the feedstock for bio-butanol production through the recycling and reusing of wastewater. The optimized conditions resulted in a high yield of monomer sugars for the production of cellulosic ABE. This alternative process is significant for reducing wastewater discharge and ensuring high pulping performances.