Fermentation of undetoxified sugarcane bagasse hydrolyzates using a two stage hydrothermal and mechanical refining pretreatment

Authors: WANG, ZHAOQIN - University Of Illinois; Dien, Bruce; RAUSCH, KENT - University Of Illinois; TUMBLESON, M.E. - University Of Illinois; SINGH, VIJAY - University Of Illinois

Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2018
Publication Date: 8/1/2018
Citation: Wang, Z., Dien, B.S., Rausch, K.D,. Tumbleson, M.E., Singh, V. 2018. Fermentation of undetoxified sugarcane bagasse hydrolyzates using a two stage hydrothermal and mechanical refining pretreatment. Bioresource Technology. 261:313-321. https://doi.org/10.1016/j.biortech.2018.04.018.
DOI: https://doi.org/10.1016/j.biortech.2018.04.018

Interpretive Summary: Economical and environmentally friendly pretreatment technologies are required for commercial conversion of lignocellulosic feedstocks to fermentable saccharides for biofuel production. Combining thermal and mechanical refining pretreatments should afford the advantage of allowing high solids processing and an enzymatic hydrolyzate amendable to fermentation. In this study, liquid hot water pretreatment was combined with disk milling for pretreatment of sugarcane bagasse. Sugarcane bagasse was pretreated using liquid hot water (LHW) at 140 to 180°C for 10 min (20%w/w solids content) and then disk milled. Disk milling improved glucose release 41 to 177% and ethanol production from glucose/xylose cofermentation by 80% compared to only using LHW pretreatment. The highest ethanol conversion efficiency achieved was 94%, which was observed when bagasse was treated at 180°C with LHW and disk milled. However, a small amount of residual xylose (3g/L) was indicative that further improvement could be achieved to increase ethanol production.

Technical Abstract: Economical and environmentally friendly pretreatment technologies are required for commercial conversion of lignocellulosic feedstocks to fermentable sugars for fermentation to biofuels. In this paper, a novel pretreatment technology was developed for conversion of sugarcane bagasse into ethanol using commercial enzymes and Saccharomyces. The pretreatment consists of reacting with pressurized hot water (140-180°C) followed by passing repeatedly through a disk mill. It is expected that the hot water will soften up the biomass fibers and disk milling will shear the fibers, which would make the fibers more amendable to digestion by enzymes to release sugars. In this case, it was observed that pretreating at 180°C gave the best ethanol yield, which was 94% of maximum and is considered very high. This paper will be of interest to current fuel ethanol producers looking to expand their range of feedstocks so as to produce more ethanol.