Modified alkaline peroxide pretreatment: An efficient path forward for bioethanol production from bamboo

• Published in: Energy conversion and management 2020-11, Vol.224 (1), p.113365, Article 113365
• Main Authors: Huang, Chen, Zhan, Yunni, Du, Xinghu, Zhou, Yang, Yu, Longxiang, Meng, Xianzhi, Jiao, Jian, Fang, Guigan, Ragauskas, Arthur J.
• Format: Article
• Language: English
• Subjects: 30 DIRECT ENERGY CONVERSION; Bamboo; Biofuels; Energy balance; Enzymatic hydrolysis; Ethanol; Fermentation; Glucan; Hydrogen peroxide; Lignin; Lignin removal; Modified alkaline hydrogen peroxide pretreatment; Pretreatment; Saccharification; Saturation; Simultaneous saccharification and fermentation; Xylan
• ISSN: 0196-8904; 1879-2227
• DOI: 10.1016/j.enconman.2020.113365

•The high lignin content of bamboo is well known to make this abundant bioresource difficult to use for cellulosic ethanol.•This study examines and identifies an alkaline ethanol, peroxide pretreatment of bamboo that significantly decreases its recalcitrance.•The results are documented in enhanced sugar release, improved ethanol generation from fermentation and improved techno-economic evaluation. To overcome the typical delignification saturation point of alkaline peroxide pretreatment and further facilitate lignin removal, a novel modified alkaline hydrogen peroxide pretreatment (MAHP) was proposed by introducing ethanol into the reaction system. The dosages of H2O2, ethanol, and pretreatment temperature were optimized, and the results revealed that a maximum lignin removal as high as 79.25% could be achieved at only 100 °C, 3 wt% H2O2 concentration and 1 wt% ethanol concentration. Meanwhile, 76.5% of glucan and 56.0% of xylan were preserved at this pretreatment condition. By overcoming the delignification saturation point, enzymatic hydrolysis efficiency was remarkably enhanced, achieving 96.76% and 97.38% of glucan and xylan conversion, respectively, which are 7.4 and 11.4 times as compared to that of the untreated bamboo. Furthermore, the simultaneous saccharification and fermentation (SSF) result indicated an identical ethanol yield of ~75% when elevating the SSF solid loading from 5% to 30%. Based on the sequential SSF and xylose fermentation results, about 5.6 tons of bamboo would be consumed to produce 1 ton of ethanol. Finally, the energy balance revealed that a positive balance of 1255.4 KJ could be generated via processing 1 kg bamboo. The results demonstrate that the MAHP is a promising high-efficiency pretreatment technology for bamboo due to the mild pretreatment severity and robust ethanol yield.