Influence of inhibitors on the hydrolysis of spruce residues for the production of bioethanol

Examensarbete för masterexamen
Master Thesis
Sundberg, David
Sustainable fuel ethanol may be produced from lignocellulosic materials such as wood and straw. The use of forestry residues may allow for bioethanol to be produced in a sustainable way. However, very little systematic work has been performed on the pretreatment, hydrolysis and fermentation of forest residues. Utilizing forest residues would increase the value of forest products, contribute to the development of a circular economy and combat climate change by diminishing the need for fossil fuels in the transportation sector. In this project, the inhibitory effect on the enzymes responsible for glucose release from Norway spruce (Picea abies) residues from branches, tips and needles during enzymatic hydrolysis have been investigated. Inhibitors native to the material and produced during the pretreatment increases the process cost and diminishes yields for bioethanol production. An anaerobic parallel shake flask system for performing the hydrolysis has been developed and assembled. The material has been both chemically and physically characterized, and method development for analysis of pretreated and hydrolyzed material using high performance liquid chromatography and ion chromatography has been done. Method development using a Kinetex F5 Core-shell LC column, Rezex™ RPMMonosaccharide Pb+2 (8%) column, and a Rezex™ ROA-Organic Acid H+ (8%), 150 x 7.8 mm LC column has laid a foundation for future method development that might result in large time savings for the analysis of both pretreated and hydrolyzed spruce residue material. The holocellulosic fractions of the material were consistent with the literature. It was concluded that mild pretreatment conditions were likely to produce the highest amount of releasable sugars. Nevertheless, the materials were quite recalcitrant, and only about 30% of the theoretical glucose yield on cellulose was achieved. Despite some indications that increased ethanol and acetate concentrations in the hydrolysate decreases the hydrolysis rate and yield respectively it is likely that increasing inhibitor concentrations within realistic spans do not affect productivity and yield significantly.
Livsvetenskaper, Kemiska processer, Annan industriell bioteknik, Förnyelsebar bioenergi, Life Science, Chemical Process Engineering, Other Industrial Biotechnology, Renewable Bioenergy Research
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