Assessment of fermentability of steam-pretreated spruce tips, needles and branches for bioethanol applications

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dc.contributor.authorAsp, Tobias
dc.contributor.departmentChalmers tekniska högskola / Institutionen för biologi och biotekniksv
dc.contributor.departmentChalmers University of Technology / Department of Biology and Biological Engineeringen
dc.date.accessioned2019-07-03T14:54:56Z
dc.date.available2019-07-03T14:54:56Z
dc.date.issued2018
dc.description.abstractThe production of bioethanol from fermentation-based bioprocesses utilizing ligno-celluosic feedstocks is an option for replacing fossil based fuels. By using genetically modified yeasts that co-consume glucose and xylose, it is possible to ferment lingo-cellulosic materials such as spruce for bioethanol production. In this project the fermentability of spruce tips, needles and branches, pretreated by acid-catalyzed steam explosion according to a design of experiments plan, was evaluated in terms of ethanol titer, rate and yield as well as cell viability. In order to ferment the spruce tips, needles and branches, suÿcient cell concentrations are needed. A preculture method was developed where enough cells were produced and harvested in the same physiological state in di˙erent batches for simultaneous saccharification and co-fermentation. A anaerobic shake flask system was used to ferment the spruce tips, needles and branches. Final ethanol titers of up to 10 g l-1, average volumetric ethanol production rates of up to 0.35 g l-1 h-1 and final yields of ethanol on available glucose and on available glucose together with xylose of up to 0.19 gEthanol gGlucose-1 and 0.16 gEthanol gGlucose+Xylose-1 respectively were observed. The final cell concentrations, colony forming units and growth rates observed were all fairly low values of up to 3.00 x 105 cells ml-1, 1.19 x 107 CFU ml-1 and 2.36 x 10-2 h-1 respectively. Even though there may be some indications on preferable pretreatment conditions in terms of fermentability, more testing and experiments are required to make statisti-cally significant recommendations.However, trends observed in this project points to either high temperature and short time or low temperature and long time as prefer-able pretreatment process conditions. Materials pretreated under these conditions showed the highest final titers and yields.
dc.identifier.urihttps://hdl.handle.net/20.500.12380/256111
dc.language.isoeng
dc.setspec.uppsokLifeEarthScience
dc.subjectLivsvetenskaper
dc.subjectKemiska processer
dc.subjectAnnan kemiteknik
dc.subjectAnnan industriell bioteknik
dc.subjectLife Science
dc.subjectChemical Process Engineering
dc.subjectOther Chemical Engineering
dc.subjectOther Industrial Biotechnology
dc.titleAssessment of fermentability of steam-pretreated spruce tips, needles and branches for bioethanol applications
dc.type.degreeExamensarbete för masterexamensv
dc.type.degreeMaster Thesisen
dc.type.uppsokH
local.programmeBiotechnology (MPBIO), MSc
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