Improved co-production of ethanol and xylitol from low-temperature aqueous ammonia pretreated sugarcane bagasse using two-stage high solids enzymatic hydrolysis and Candida tropicalis

Kanak Raj and Chandraraj Krishnan

Renewable Energy, 2020, vol. 153, issue C, 392-403

Abstract: Process economics of cellulosic ethanol production can be improved by co-production of high value products. Xylitol is a high value nutraceutical and attracted attention as a co-product in cellulosic ethanol process. Here, the production of ethanol and xylitol from sugarcane bagasse pretreated by low-temperature aqueous ammonia soaking was improved by two-stage high solids enzymatic hydrolysis and separate fermentation of glucose and xylose using Candida tropicalis. First-stage high solids fed-batch enzymatic hydrolysis of pretreated bagasse in 3 L bioreactor resulted in 42.6 g/l xylose. The residual solids rich in cellulose were efficiently hydrolyzed by cellulase in the second-stage to glucose. The second stage hydrolysis at 20% solids loading in bioreactor showed 81% efficiency with a glucose concentration of 115.8 g/l. The separate fermentation of the xylose with C. tropicalis in two-stage aeration resulted in 34.5 g/l of xylitol. Fermentation of the glucose by C. tropicalis produced 55.64 g/l of ethanol. Simultaneous saccharification and fermentation of cellulose rich solids from first stage hydrolysis produced 57.2 g/l of ethanol. These results showed that two-stage enzymatic hydrolysis of low-temperature aqueous ammonia pretreated biomass facilitated higher yields and efficiency of production of ethanol and xylitol.

Keywords: Aqueous ammonia soaking; Sugarcane bagasse; Cellulosic ethanol; Xylitol; Two-stage hydrolysis; Two-stage aeration; High solids hydrolysis; Candida tropicalis (search for similar items in EconPapers)
Date: 2020
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Citations: View citations in EconPapers (4)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:153:y:2020:i:c:p:392-403

DOI: 10.1016/j.renene.2020.02.042

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