Refining Hemp Hurds into Fermentable Sugars or Ethanol

Z. Barta, J. M. Oliva, I. Ballesteros, D. Dienes, M. Ballesteros and K. Réczey

Abstract
Steam pretreatment is one of the most efficient pretreatment technologies employed prior to enzymatic hydrolysis of lignocellulosics to obtain high polysaccharide conversion. In this study, steam pretreatment of non-impregnated hemp hurds was investigated at two reactor scales (2 and 10 L) by varying the temperature from 200–230 °C. Glucan recoveries were relatively high (> 82 % of original content), while xylan recoveries ranged from 18–66 % of original. Conversions of glucan and xylan in enzymatic hydrolysis varied between X = 62–83 % and 46–96 %, respectively, based on glucan and xylan contents of the substrate. Ethanol yields in simultaneous saccharification and fermentation ranged from Y = 38–70 %, based on glucan and mannan contents of the substrate. The highest overall glucose yield was 336 g kg–1 dry hurds obtained at 210 °C, whereas the maximum sugar yield (glucose + xylose), 414 g kg–1 dry hurds, was achieved at 200 °C. The highest ethanol yield, 141 g kg–1 dry hurds, was obtained at 210 °C.

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Keywords
Hemp hurds, steam pretreatment, enzymatic hydrolysis, SSF, ethanol production