Tag Archives: glucose

417-424 M. Tutt, T. Kikas, H. Kahr, M. Pointner, P. Kuttner and J. Olt
Using steam explosion pretreatment method for bioethanol production from floodplain meadow hay
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Using steam explosion pretreatment method for bioethanol production from floodplain meadow hay

M. Tutt¹*, T. Kikas¹, H. Kahr², M. Pointner², P. Kuttner² and J. Olt¹

¹Institute of Technology, Estonian University of Life Sciences, Kreutzwaldi 56, EE51014 Tartu, Estonia; *Correspondence: marti.tutt@emu.ee 2Upper Austria University of Applied Sciences, Wels Campus, Stelzhamerstraße 23, 4600 Wels, Austria

Abstract:

This article investigates influence of the steam explosion pretreatment method at different temperatures on sugar conversion rates and bioethanol production efficiencies from floodplain meadow hay. Floodplain meadow hay is used as a raw material, because these semi-natural grasslands need regular maintenance to preserve their high biodiversity. So far, this biomass has been largely unused, but it could provide a good feedstock for bioethanol production. In this work, steam explosion pretreatment is used in combination with enzymatic hydrolysis. Effects of steam explosion pretreatment on the fibre content and cell wall structure are also studied. Results from fibre analysis show, that the floodplain meadow hay has very high lignin content of 24.16%, but relatively low cellulose content of 27.19%. Highest cellulose to glucose conversion rate of 234.6 g kg-1 and ethanol yield of 115.7 g kg-1 of biomass were achieved with the steam explosion pretreatment at 200°C. Scanning electron microscope (SEM) images show that pretreatment at 150°C does very little damage to plant cells, while steam explosion at 200°C disintegrates most of the plant cell walls and exposes cellulose fibres.

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215-220 M. Tutt, T. Kikas and J. Olt
Influence of harvesting time on biochemical composition and glucose yield from hemp
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Influence of harvesting time on biochemical composition and glucose yield from hemp

M. Tutt*, T. Kikas and J. Olt

Institute of Technology, Estonian University of Life Sciences, 56 Kreutzwaldi, EE51014, Tartu, Estonia;
*Correspondence: marti.tutt@emu.ee

Abstract:

Abstract. This article investigates the influence of different harvesting times of hemp samples on their biochemical composition and glucose conversion  yield. Samples  were harvested from experimental fields of the Estonian University of Life Sciences from July to September in 2011. Dilute  sulfuric  acid  solution  was  used  for  pretreatment  in  combination  with  enzymatic hydrolysis.  Results  indicate  that  the  highest  glucose  conversion  rate  of  204.1 g kg-1  of  dry matter of biomass was achieved by samples harvested on the 18th of August. The lowest glucose yield  of  170.3 g kg-1  was  achieved  by  samples  harvested  on  25th  of  August,  which  also  had  a very  low  hydrolysis  efficiency  of  46.9%.  Biochemical  composition  and  glucose  conversion efficiencies of samples vary in time. Samples harvested in September have higher cellulose and lignin  content  than  samples  harvested  in  July.  However,  glucose  conversion  efficiencies decrease significantly in later samples. Average hydrolysis efficiency was 51.4%.  

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269-276 M. Tutt, T. Kikas and J. Olt
Influence of different pretreatment methods on bioethanol production from wheat straw
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Influence of different pretreatment methods on bioethanol production from wheat straw

M. Tutt, T. Kikas and J. Olt

Institute of Technology, Estonian University of Life Sciences, Kreutzwaldi 56,
EE51014, Tartu, Estonia; e-mail: marti.tutt@emu.ee

Abstract:

Article investigates the influence of different pretreatment methods on sugar
conversion and bioethanol production. Different dilute acid and alkaline pretreatment methods
are compared to determine the best pretreatment method to give the highest glucose and ethanol
yields under the mild operating conditions. Wheat straw is used as a raw material as it is the
most widely grown cereal in Europe. Dilute sulfuric acid, hydrochloric acid, nitric acid and
potassium hydroxide solutions are used for pretreatment in combination with enzymatic
hydrolysis. Results indicate that the highest cellulose-to-glucose conversion rate of 316.7 g kg-1
of biomass is achieved by the pretreatment with nitric acid. The lowest glucose concentration of
221.3 g kg-1 is achieved by hydrochloric acid. In the wheat straw samples pretreated with
sulfuric acid and KOH, two different approaches are used. Solid phase of half the samples is
rinsed with water before adding enzymes, and the rest of the samples are not. The rinsed
samples pretreated with KOH solution give the highest ethanol yield of 104.3 g kg-1, while the
lowest ethanol yield is 67.7 g kg-1 from samples pretreated with HCl solution. Unrinsed samples
and rinsed samples pretreated with sulfuric acid give an ethanol yield of 78.7 g kg-1 and
92.0 g kg-1, respectively. These results indicate that rinsing the solid phase of the samples with
distilled water before hydrolysis removes most of the inhibitory compounds formed during the
pretreatment with dilute acid and increases fermentation efficiency by approximately 12%. 

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