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Enzyme-based control of oxalic acid in the pulp and paper industry
Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
STFI-Packforsk AB, Swedish Pulp and Paper Research Institute, Stockholm.
Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
2008 (English)In: Enzyme and microbial technology, ISSN 0141-0229, E-ISSN 1879-0909, Vol. 43, p. 78-83Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2008. Vol. 43, p. 78-83
National Category
Biomedical Laboratory Science/Technology Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
Research subject
Biomedical Sciences
Identifiers
URN: urn:nbn:se:kau:diva-1968DOI: 10.1016/j.enzmictec.2007.11.014OAI: oai:DiVA.org:kau-1968DiVA, id: diva2:5243
Available from: 2008-02-01 Created: 2008-02-01 Last updated: 2017-12-07Bibliographically approved
In thesis
1. Chemical characterization in the biorefinery of lignocellulose: Formation and management of oxalic acid and analysis of feedstocks for bioethanol production
Open this publication in new window or tab >>Chemical characterization in the biorefinery of lignocellulose: Formation and management of oxalic acid and analysis of feedstocks for bioethanol production
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The pulp and paper industry is entering a new era. Pulp mills will be transformed to biorefineries that produce not only pulp, but also biofuels and novel products from lignocellulose. This thesis addresses problems connected with the industrial transition to environmental-friendly technologies and the implementation of the biorefinery concept.

Peroxide bleaching and enhanced recirculation of process water may lead to increased problems with oxalate scaling. Enzymatic elimination of the oxalate problem could be the ultimate industrial solution. The activities of oxalate oxidase, oxalate decarboxylase and a novel oxalate-degrading enzyme provided by Novozymes have been tested in industrial bleaching filtrates. Chemical characterization of the filtrates was used in combination with multivariate data analysis to identify potential enzyme inhibitors. A method based on oxalate oxidase was developed to determine the levels of oxalic acid in process water.

The precursors of oxalic acid formed during bleaching of pulp have been reassessed. New experimental data indicate that alkaline oxidative degradation of dissolved carbohydrates is the main source of oxalic acid. These findings are contradictory to previous hypotheses, which have been focused on lignin. Xylan was more important than lignin as precursor of oxalic acid under peroxide-bleaching conditions. Hot-water extraction of hemicelluloses from softwood mechanical pulp prior to the peroxide-bleaching stage reduced the formation of oxalic acid by one third.

Lignocellulosic materials were characterized chemically with regard to their suitability as feedstocks in biorefineries producing bioethanol. Four agricultural and agro-industrial residues were investigated; cassava stalks, peanut shells, rice hulls, and sugarcane bagasse. Pretreated sugarcane bagasse was the material that was most susceptible to hydrolysis by cellulolytic enzymes. Waste fiber sludges from three pulp mills were characterized. The waste fiber sludge with the lowest content of lignin was hydrolyzed most efficiently by the enzymes. Oligomeric xylan fragments were isolated as by-products from a waste fiber sludge. Hydrolysis of the waste fiber sludges resulted in solid residues with improved fuel properties. The waste fibers were found to be suitable as a feedstock for the production of biofuels in a pulp mill-based biorefinery.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2008. p. 56
Series
Karlstad University Studies, ISSN 1403-8099 ; 2008:5
Keywords
biorefinery, enzymes, ethanol, lignocellulosic feedstocks, oxalic acid, scaling
National Category
Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
Research subject
Chemistry
Identifiers
urn:nbn:se:kau:diva-1362 (URN)978-91-7063-162-7 (ISBN)
Public defence
2008-02-15, Nyqvistsalen, 9C 203, Karlstad, 13:15
Opponent
Supervisors
Available from: 2008-02-01 Created: 2008-02-01 Last updated: 2011-12-21Bibliographically approved
2. Industrial applications and properties of oxalate-degrading enzymes
Open this publication in new window or tab >>Industrial applications and properties of oxalate-degrading enzymes
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Oxalate-degrading enzymes were investigated with focus on potential applications in the pulp and paper industry and in active packaging. Changes introduced to make the pulp and paper industry more environmentally friendly, such as recirculation of process-water streams and elementary chlorine free bleaching of pulp, have led to increasing problems with precipitation of calcium oxalate. The potential of using enzymes for degradation of oxalic acid in industrial bleaching filtrates was explored to find a way to decrease the problem.

The studies included chemical characterization and enzymatic treatments of 34 filtrates from kraft, mechanical, and sulfite pulping. Eight oxalate-degrading enzymes were included in the experiments. The treatments of the filtrates were affected by substances that inhibit oxalate-degrading enzymes. Multivariate data analysis, analytical treatment of filtrates with ion-exchange resins, and analysis of the effects of separate compounds on the enzyme activity were employed as tools to investigate inhibiting substances and groups of inhibitors. The experiments with ion-exchangers indicated that the inhibitors included anions, cations, as well as uncharged substances. Sulfite (≥1 mM) caused complete or almost complete inhibition of all oxalate-degrading enzymes so far examined, while the effects of chlorine oxyanions differed for the various enzymes investigated. A newly discovered oxalate decarboxylase was chosen for experiments performed directly in a mill producing mechanical pulp. The new enzyme degraded 70% of the oxalic acid in one hour, while the well-characterized oxalate decarboxylase from Aspergillus niger degraded <5% of the oxalic acid during the same period of time.

Oxalate decarboxylase from the white-rot basidiomycete fungus Trametes versicolor was purified by using chromatographic methods and characterized with gel electrophoresis and tandem mass spectrometry. Results indicate that it is a 69-kDa heavily glycosylated enzyme with optimal activity at pH 2.5.

Experiments designed to investigate the potential of using oxalate oxidase from barley in active packaging showed that it could be entrapped with retained catalytic activity in a latex-polymer matrix. Furthermore, the experiments indicate that oxalate oxidase can be used in active packaging either as an oxalic acid scavenger or as an oxygen scavenger.

Place, publisher, year, edition, pages
Karlstad: Karlstad University, 2010. p. 61
Series
Karlstad University Studies, ISSN 1403-8099 ; 2010:21
Keywords
Oxalic acid, oxalate oxidase, oxalate decarboxylase, calcium oxalate, scaling, active packaging
National Category
Chemical Sciences
Research subject
Chemistry
Identifiers
urn:nbn:se:kau:diva-5916 (URN)978-91-7063-313-3 (ISBN)
Public defence
2010-09-24, Ljungbergssalen, 21A 244, Karsltads universitet, Karlstad, 10:15 (English)
Opponent
Supervisors
Available from: 2010-09-06 Created: 2010-06-18 Last updated: 2011-11-03Bibliographically approved

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Winestrand, SandraJönsson, Leif J.

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