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

Abstract 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 01–06 h, and sulfuric acid concentration 0.005–1.00 N at 120 °C in an autoclave. The conditions optimized for acid hydrolysis of waste paper were 0.50 N H 2 SO 4 at 120 °C for 02 h 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 ± 0.16 g/l with 77.54 ± 4.47% of fermentation efficiency.