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Comparison between oxalate decarboxylase and oxalate oxidase in the degradation of oxalic acid in filtrates from the pulp and paper industry
Applied Microbiology, Lund University/Lund Institute of Technology.
Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
Karlstads universitet, Fakulteten för teknik- och naturvetenskap, Avdelningen för kemi och biomedicinsk vetenskap.
Karlstads universitet, Fakulteten för teknik- och naturvetenskap.
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(Engelska)Manuskript (Övrigt vetenskapligt)
Nationell ämneskategori
Kemi
Forskningsämne
Kemi
Identifikatorer
URN: urn:nbn:se:kau:diva-1967OAI: oai:DiVA.org:kau-1967DiVA, id: diva2:5242
Tillgänglig från: 2008-02-01 Skapad: 2008-02-01 Senast uppdaterad: 2011-11-14Bibliografiskt granskad
Ingår i avhandling
1. Chemical characterization in the biorefinery of lignocellulose: Formation and management of oxalic acid and analysis of feedstocks for bioethanol production
Öppna denna publikation i ny flik eller fönster >>Chemical characterization in the biorefinery of lignocellulose: Formation and management of oxalic acid and analysis of feedstocks for bioethanol production
2008 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
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.

Ort, förlag, år, upplaga, sidor
Karlstad: Karlstads universitet, 2008. s. 56
Serie
Karlstad University Studies, ISSN 1403-8099 ; 2008:5
Nyckelord
biorefinery, enzymes, ethanol, lignocellulosic feedstocks, oxalic acid, scaling
Nationell ämneskategori
Medicinsk bioteknologi (med inriktning mot cellbiologi (inklusive stamcellsbiologi), molekylärbiologi, mikrobiologi, biokemi eller biofarmaci)
Forskningsämne
Kemi
Identifikatorer
urn:nbn:se:kau:diva-1362 (URN)978-91-7063-162-7 (ISBN)
Disputation
2008-02-15, Nyqvistsalen, 9C 203, Karlstad, 13:15
Opponent
Handledare
Tillgänglig från: 2008-02-01 Skapad: 2008-02-01 Senast uppdaterad: 2011-12-21Bibliografiskt granskad

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Winestrand, Sandra

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Avdelningen för kemi och biomedicinsk vetenskapFakulteten för teknik- och naturvetenskap
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