Tag Archives: cellulose

215-220 M. Tutt, T. Kikas and J. Olt
Influence of harvesting time on biochemical composition and glucose yield from hemp
Abstract |
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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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311-316 K. Kauer, H. Raave, R. Viiralt, T. Köster, M. Noormets-Shansky,T. Laidna, I. Keres, A. Parol and A. Selge
Effect of clippings management on turfgrass sward productivity and nitrogen content in the clippings and soil
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Effect of clippings management on turfgrass sward productivity and nitrogen content in the clippings and soil

K. Kauer¹, H. Raave², R. Viiralt², T. Köster³, M. Noormets-Shansky²,T. Laidna², I. Keres², A. Parol² and A. Selge²

¹Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences,Kreutzwaldi 1, 51014 Tartu, Estonia; e-mail: karin.kauer@emu.ee
²Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences,Kreutzwaldi 1, 51014 Tartu, Estonia
³Agricultural Research Centre, Teaduse 4/6, 75501 Saku, Estonia

Abstract:

The maintenance of turfgrass sward includes mowing and fertilization. Every year turfgrass sward produces a sizeable amount of clippings containing large amounts of nutrients which will be available for plants during the decomposition process. The aim of this research was to study clippings decomposition speed, the effect of returned clippings to the turfgrass sward’s clippings yield and total nitrogen content in clippings and soil. The study was carried out on turfgrass sward (seed mixture composition Festuca rubra rubra 50% and Poa pratensis 50%). The turfgrass clippings were either removed after cutting or returned to the plots. The clippings yield and nitrogen content in the clippings were measured after every cutting. The soil samples from different plots were analyzed for total nitrogen at the beginning and the end of the growing season. The decomposition dynamics of clippings was studied using the litterbag technique. Also the nitrogen mineralization from decaying material and the concentration changes of cellulose and lignin were studied during 12 weeks.The results showed that the turfgrass clippings mass and the content of nitrogen decreasedduring the decomposition process very quickly. The degradation of cellulose takes place after about 30% of initial weight decomposition. During the 12 week study period we did not fix the beginning of lignin decomposition. Higher productivity was obtained in treatments where clippings were removed. N content did not differ in plant from plots where clippings returned or removed but N content in soil of plots with clippings returned decreased compared to N content in soil of plots where clippings were removed.

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