Bioethanol production from waste paper acid pretreated hydrolyzate with xylose fermenting Pichia stipitis

► The study evaluates acid pretreated waste paper hydrolyzate for bioethanol production. ► Presence of 70.12±4.88% of holocellulose makes waste paper a prospective renewable biomass. ► We model acid hydrolysis of waste paper for recovery of reducing sugars from hydrolyzate. ► Fermentation with Pichia stipitis resulted with 77.54±4.47% of fermentation efficiency. This study evaluates acid pretreated waste paper hydrolyzate as feedstock for bioethanol production. The presence of 70.12±4.88% carbohydrates (holocellulose) makes waste paper a prospective and renewable biomass for bioethanol production. The waste paper was found to contain α-cellulose (61.5±3.49%), pentosans (7.42±0.36%), lignin (16.33±0.96%), ash (12.50±0.33%) and moisture (8.28±0.63%). Conditions for the dilute acid pretreatment of waste paper were optimized by varying solid/liquid ratio 1:8–1:14 (w/v), reaction time 01–06h, and sulfuric acid concentration 0.005–1.00N at 120°C in an autoclave. The conditions optimized for acid hydrolysis of waste paper were 0.50N H2SO4 at 120°C for 02h reaction time keeping biomass:acid ratio 1:10 (w/v) for recovery of reducing sugars from waste paper hydrolyzate. Fermentation of acid hydrolyzate of waste paper with Pichia stipitis under optimum condition resulted in ethanol production 3.73±0.16g/l with 77.54±4.47% of fermentation efficiency.