Vacuum-assisted black liquor-recycling enhances the sugar yield of sugarcane bagasse and decreases water and alkali consumption

• Published in: Bioresource technology Vol. 309; p. 123349
• Main Authors: Fan, Zhaodi, Lin, Jianghai, Wu, Jiahui, Zhang, Licheng, Lyu, Xiaojing, Xiao, Wenjuan, Gong, Yingxue, Xu, Yuan, Liu, Zehuan
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.08.2020
• Subjects: Alkali pretreatment; alkali treatment; Alkalies; Bioethanol; Black liquor recycling; Cellulose; crop yield; enzymatic hydrolysis; ethanol; Fermentation; glucose; Hydrolysis; Saccharum; Sugarcane bagasse; Sugars; Vacuum-assisted pretreatment; waste liquors; Water; water utilization; Alkali pretreatment; Bioethanol; Vacuum-assisted pretreatment; Black liquor recycling; Sugarcane bagasse
• ISSN: 0960-8524; 1873-2976; 1873-2976
• DOI: 10.1016/j.biortech.2020.123349

•Black liquor was recycled to pretreat SCB under vacuum conditions.•Peak glucose yields were achieved at 0.35 g/g raw SCB following VABLR pretreatment.•No obvious variance in enzymatic digestibility after at least eight cycles of BL reuse. Black liquor (BL) remains a critical problem during alkaline pretreatment. To solve this issue, a novel pretreatment strategy termed vacuum-assisted black liquor-recycling pretreatment, was established to pretreat sugarcane bagasse (SCB). Firstly, SCB was pretreated with 2% NaOH at 121 °C for 1 h under vacuum conditions. The produced BL was used for subsequent pretreatments after pH recovery with NaOH. The pretreated SCBs were subject to enzymatic hydrolysis and separate hydrolyzation and fermentation (SHF) without washing to neutral pH. BL was recycled on seven occasions. The results indicated that glucose yields did not significantly differ between pretreatment with NaOH and recovered BL. The enzymatic hydrolysis and the fermentation resulted in maximum 0.35 g/g of glucose yield and 116.5 g/kg of ethanol yield respectively. Compared with conventional pretreatment with NaOH, the VABLR method showed high conversion rates of cellulose into monosaccharaides, whilst preserving ~20% and ~46% of alkali and water usage, respectively.