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Separate versus simultaneous saccharification and fermentation of two-step steam pretreated softwood for ethanol production

Söderström, Johanna LU ; Galbe, Mats LU and Zacchi, Guido LU (2005) In Journal of Wood Chemistry and Technology 25(3). p.187-202
Abstract
In two previous studies, optimal conditions were identified for two-step steam pretreatment Of SO2- and H2SO4-impregnated softwood. In the present study the yield of sugar and ethanol was determined in a process development unit where pretreatment was performed in a 10-L reactor and simultaneous sacchatification and fermentation (SSF) or enzymatic hydrolysis (EH) were performed in 30-L reactors. The study showed that a steam pretreatment reactor should be larger than 2 L to yield acceptable results. Two pretreatment combinations were studied. In the H2SO4 case, the first pretreatment step was at 180 degrees C for 10 min with 0.5% H2SO4 and the second step at 210 degrees C for 2min with 1% H2SO4. In the SO2 case, first step was at 190... (More)
In two previous studies, optimal conditions were identified for two-step steam pretreatment Of SO2- and H2SO4-impregnated softwood. In the present study the yield of sugar and ethanol was determined in a process development unit where pretreatment was performed in a 10-L reactor and simultaneous sacchatification and fermentation (SSF) or enzymatic hydrolysis (EH) were performed in 30-L reactors. The study showed that a steam pretreatment reactor should be larger than 2 L to yield acceptable results. Two pretreatment combinations were studied. In the H2SO4 case, the first pretreatment step was at 180 degrees C for 10 min with 0.5% H2SO4 and the second step at 210 degrees C for 2min with 1% H2SO4. In the SO2 case, first step was at 190 degrees C for 2 min followed by a second step at 210 degrees C for 5 min. The concentration of SO2 was 3% in both steps. EH and SSF were performed on the whole slurry after the second pretreatment step to determine the yield of sugars and ethanol. The liquid after the first pretreatment step was also analyzed and fermented. When SSF and EH were performed at the same dry matter content and enzymatic activity, the ethanol yield in SSF exceeded the yield obtained with EH in both pretreatment cases, even when 100% yield in the fermentation step was assumed. Thus SSF is a better process if yield is the main priority. Comparison of the yields with the two acid catalysts showed higher yields with SO2 in both SSF and EH. The overall ethanol yield following SSF of SO2-impregnated and pretreated wood reached 81% of the theoretical, that is, 357 liters per metric ton of dry raw material. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Wood Chemistry and Technology
volume
25
issue
3
pages
187 - 202
publisher
Taylor & Francis
external identifiers
  • wos:000232470700006
  • scopus:27344452914
ISSN
0277-3813
DOI
10.1080/02773810500191807
language
English
LU publication?
yes
id
66df4a52-6747-4b9d-9809-a1197efdbc88 (old id 151597)
date added to LUP
2007-06-25 16:01:21
date last changed
2017-04-30 13:09:51
@article{66df4a52-6747-4b9d-9809-a1197efdbc88,
  abstract     = {In two previous studies, optimal conditions were identified for two-step steam pretreatment Of SO2- and H2SO4-impregnated softwood. In the present study the yield of sugar and ethanol was determined in a process development unit where pretreatment was performed in a 10-L reactor and simultaneous sacchatification and fermentation (SSF) or enzymatic hydrolysis (EH) were performed in 30-L reactors. The study showed that a steam pretreatment reactor should be larger than 2 L to yield acceptable results. Two pretreatment combinations were studied. In the H2SO4 case, the first pretreatment step was at 180 degrees C for 10 min with 0.5% H2SO4 and the second step at 210 degrees C for 2min with 1% H2SO4. In the SO2 case, first step was at 190 degrees C for 2 min followed by a second step at 210 degrees C for 5 min. The concentration of SO2 was 3% in both steps. EH and SSF were performed on the whole slurry after the second pretreatment step to determine the yield of sugars and ethanol. The liquid after the first pretreatment step was also analyzed and fermented. When SSF and EH were performed at the same dry matter content and enzymatic activity, the ethanol yield in SSF exceeded the yield obtained with EH in both pretreatment cases, even when 100% yield in the fermentation step was assumed. Thus SSF is a better process if yield is the main priority. Comparison of the yields with the two acid catalysts showed higher yields with SO2 in both SSF and EH. The overall ethanol yield following SSF of SO2-impregnated and pretreated wood reached 81% of the theoretical, that is, 357 liters per metric ton of dry raw material.},
  author       = {Söderström, Johanna and Galbe, Mats and Zacchi, Guido},
  issn         = {0277-3813},
  language     = {eng},
  number       = {3},
  pages        = {187--202},
  publisher    = {Taylor & Francis},
  series       = {Journal of Wood Chemistry and Technology},
  title        = {Separate versus simultaneous saccharification and fermentation of two-step steam pretreated softwood for ethanol production},
  url          = {http://dx.doi.org/10.1080/02773810500191807},
  volume       = {25},
  year         = {2005},
}