In this work, spent sulfite liquor (SSL) was used to produce butanol after two-levels of inhibitors removal. SSL component analysis was conducted, and the results showed that SSL contained a large proportion of pentose, hexose, lignosulfonates and other inhibitors. Based on the integrated biorefinery concept, three utilization routes were proposed employing the coupling of nanofiltration and ultrafiltration techniques. The route that uses nanofiltration to separate sugars for fermentation and lignosulfonates for further fractionation using ultrafiltration was chosen in this study. A 200-Da nanofiltration membrane was used and resulted in a recovery of 83.20% of lignosulfonates and a loss of 19.14% sugars. Nanofiltration permeate started to produce 14.32 g/L ethanol, but only 0.25 g/L butanol was observed in the acetone-butanol-ethanol (ABE) fermentation, indicating that the fermentation inhibition still existed. After the removal of second-level inhibitors through decolorization and ion exchange, an improved ABE production from SSL was achieved compared with its control test of commercial sugar mixture without inhibitors (12.96 versus 12.65 g/L butanol, and 21.09 versus 20.38 g/L ABE). Meanwhile, the fermentation inhibitors of SSL were thoroughly removed. This study provides a sustainable approach to produce value-added products from wastewater, and can reduce environmental pollution and save capital. (C) 2020 Elsevier Ltd. All rights reserved.