The Honourable Mr. Ralph Loffmark, British Columbia's Minister of Trade and Commerce, has taken the position that demand for woodpulp will greatly exceed the supply during the next five years. On the other hand, leaders of British Columbia's pulp and paper industry fear that a large surplus of pulp is inevitable. In this thesis, the difference of opinion was examined by forecasting demand for paper and paperboard for the period of 1965 to 1975. From this estimate was derived the expected requirements for chemical pulp and bleached sulphate market pulp for the same period. The demand for bleached sulphate was then compared with the potential supply, leading to the judgement that a surplus condition will exist. Finally, the principal factors which would affect the financial outcome for an independent bleached sulphate pulp mill were analyzed. The conclusion was reached that an independent firm would be profitable in spite of the anticipated surplus. / Business, Sauder School of / Graduate

Foam separation has been successfully developed on a 4-1 laboratory column, an 80-1 field column installation and a 6000 gal pilot plant trough type system as a novel process for detoxifying bleached kraft mill effluents. Toxic surface active materials such as resin and unsaturated fatty acids collect at the gas-liquid interface of rising air bubbles and concentrate in the foam. The highly toxic collapsed foam represents 1-2% by volume of the influent and is subsequently detoxified by biological treatment. Process parameters controlling detoxification efficiency are pH, gas-liquid interfacial area, initial toxicity level and mode of operation. The gas-liquid interfacial area and pH are of utmost importance. For a typical effluent with MST of 3-4 hr, approximately 20-2 30 m²/l of interfacial area given to an effluent at pH > 7.0 are required for detoxification. Foam separation is universally applicable and reliable for detoxifying kraft whole mill effluent. Over 80% of 205 samples from 10 Canadian mills were detoxified. A 1 gal/min, one and two stage continuous flow systems detoxified over 90% of samples at pH 8 and 1-2 hr retention time over 80 days of operation period. Study of detoxification mechanism indicated that foam fractionation accounts for 77.5% of detoxification, volatization for 5.4% and unidentified mechanisms for 17.1%. Depending on the mode of operation, up to 5% of effluent volume was discharged as foam. The foam volume could be reduced to < 2% by increasing foam retention time and enhancing internal reflux. Collapsed foam was readily detoxified by a biodisc or aerated lagoon process. In addition to detoxification, foam separation removed 20-60% of suspended solids, 66% resin acids, 12% B0D5 (10% TOC), 8% color and 80% foaming tendency. Suspended solids removal could be increased to 88% if an expensive dissolved air system were used for bubble generation. Commercially available equipment for foam generation and foam breaking was reviewed. Jet aerators and turbine systems were assessed as most suitable for commercial application. Pilot plant evaluation of this equipment indicated that reliable and consistent operation could be obtained. The results were used to establish empirical formulae for use in process scale up. During a 4 month continuous flow study, approximately 5-7 m²/l of gas-liquid interfacial area was provided to detoxify 80-100 gal/min of mill A effluent with MST of 6-10 hr. The detoxification success rate of a large number of samples increased from 50 to 86 and to 100% as the operation changed from 1 to 2 to 3 stages. The foam produced by the pilot plant was collapsed by a 12" diameter turbine at 100% efficiency all the time. Costs of foam separation were examined for a projected 3 stage foam separation process, treating 25 M gal/day of bleached kraft whole mill effluent. Capital costs for pH control, foam generation, foam breaking and foam treatment were estimated at $2.26 M. Operating costs were estimated at $2.35/ton of pulp. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

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Thesis (Ph.D. Earth and Ocean Sciences)--University of Waikato, 2007. / Title from PDF cover (viewed February 26, 2008) Includes bibliographical references (p. 148-164)

Thesis (MSc)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The extractive materials in wood often cause pitch problems in pulp mills. During pulping and bleaching extractives are released from the wood and pulp and later stick to ceramic and metal parts, forming pitch deposits. Pitch deposits impair both product quality and production rates. It decreases the efficiency of pulp washing, screening, centrifugal cleaning, and refining, and can disrupt many paper machine operations. The deposits also break loose from equipment and cause spots in the final product. There are a few triggering mechanisms that induce pitch deposition. Hydrodynamic or mechanical shear can destabilise the colloidal pitch emulsion, causing pitch to agglomerate and deposits to form. Similarly, sudden temperature drops and/or pH shocks and/or the introduction of water hardness ions from fresh water inlets or showers can also cause pitch deposits by destabilising the colloidal pitch emulsion. Inorganic salts, such as calcium carbonate, can catalyse pitch deposition by acting as the building blocks for the sticky pitch. Calcium ions in the white water can react with fatty acids, forming insoluble, sticky calcium soaps. Triglycerides have also been shown to be a major contributor to pitch deposition in kraft pulping and bleaching mills. It forms a sticky deposit to which less sticky particles attach. To attain an improved understanding of pitch problems associated with the kraft pulping and bleaching of Eucalyptus spp., various analyses were done on wood- and pulp extractives and pitch from a South African kraft pulp mill. High molecular weight compounds (involatile) constituted a large portion of the extracts and pitch. Approximately 40% of volatile Eucalyptus grandis extract was f3-sitosterol, with fatty acids (22.8%) and triglycerides (15.5%) also making a substantial contribution. Fatty acid amides were a prominent fraction of pulp extracts from the latter stages of bleaching. The amides constituted 38.3% and triglycerides 10.1% to total volatile pitch deposits. Lipases hydrolyse triglycerides and could therefore help to reduce pitch problems. Consequently 381 filamentous fungi isolated from indigenous and commercial forests in South Africa were screened for lipase activity on tributyrin and Tween 80. Eight strains were selected and the tributyrin and Tween 80 assays were repeated by monitoring lipase activity over a seven-day period. The selected strains were also assayed for their activity toward p-nitrophenyl palmitate. Ophiostoma piliferum Cartapip 58™ and Phanerochaete chrysosporium BKM-F-1767, two strains known for respectively their biodepitching and biopulping ability, were' used as controls. A few of the strains compared well and even outperformed the control strains, indicating their potential for use in pitch control. The effect of pretreatment with the eight selected fungal strains on E. grandis wood- and pulp extractives was determined. Cartapip 58™ and P. chrysosporium BKM-F-1767 were used as control strains. Several of the strains compared well to the control strains in their ability to reduce the triglyceride content of wood extract. The South African isolate, white-rot fungus Phanerochaete psuedomagnoliae nom. prov., reduced triglyceride content significantly. Consequently it can act as an agent for both biopulping and biodepitching. The treated wood samples had a lower triglyceride content than the sterile controls. Consequently more triglycerides would be released into process waters by the sterile controls than the treated samples. The effect of commerciallipases on deposited brown stock pulp extract was also evaluated. The lipases did not reduce the triglyceride content of the deposited extract. The addition of lipases in pulping and bleaching processes would therefore not affect already deposited pitch. / AFRIKAANSE OPSOMMING: Die ekstrakstowwe van hout veroorsaak dikwels 'n neerslag tydens verpulping. Gedurende verpulping en bleiking kom ekstrakstowwe van die hout enpulp vry en kleef aan keramiek- en metaalonderdele. Gevolglik benadeel dié neerslag produkkwaliteit en produksietempo. Dit verlaag die effektiwiteit van pulpwas, sifting, sentrifugale skoonmaakprosesse en suiwering, en kan die werkverrigting van papiermasjiene ontwrig. Die neerslag kan ook later los breek en kolletjies op die finale produk veroorsaak. Verskeie meganismes kan die neerslag veroorsaak. Hidrodinamiese of meganiese wrywing kan die kolloïdale ekstrakstofemulsie destabiliseer en sodoende die ekstrakstof laat konglomereer en neerslaan. Op soortgelyke wyse veroorsaak skielike temperatuurverlaging en/of pH-skokke en/of die toevoeging van ione in varswater om waterhardheid te beheer ook die neerslag deur die kolloïdale ekstrakstofemulsie te destabiliseer. Anorganiese sout soos kalsiumkarbonaat kan neerslagvorming kataliseer omdat dit optree as bousteen vir die klewerige, sementagtige ekstrakstowwe. Kalsiumione in die proseswater kan ook reageer met vetsure om onoplosbare, klewerige kalsiumsepe te vorm. Dit is bewys dat trigliseriede een van die hoofoorsake is in die vorming van die neerslag tydens kraft verpulpingen bleikingprosesse. Om die neerslagreaksie wat met die kraft verpulping en bleiking van Eucalyptus spp. geassosieer word, beter te verstaan, is verskeie analises op hout- en pulpekstrakte asook die neerslag van 'n Suid-Afrikaanse kraft verpulpingsaanleg uitgevoer. Hoë molekulêre massa (nie-vlugtige) stowwe het 'n groot gedeelte van die ekstrakte en neerslag uitgemaak. Ongeveer 40% van die vlugtige Eucalyptus grand is ekstrak bestaan uit ~-sitosterol met vet sure (22.8%) en trigliseriede (15.5%) wat ook aansienlike bydraes lewer. Vetsuuramiede verteenwoordig 'n beduidende komponent van pulpekstrak by die laaste stadiums van bleiking. Die amiede het 38.3% en trigliseriede 10.1%tot die vlugtige fraksie van die neerslag bygedra. Lipases hidroliseer trigliseriede en kan dus help om neerslagprobleme te voorkom. Gevolglik is 381 filamentagtige fungi geïsoleer uit inheemse en kommersiële woude van Suid-Afrika en hul lipase-aktiwiteit op tributyrin en Tween 80 geëvalueer. Agt rasse is geselekteer en die tributyrin en Tween 80 toetse is herhaal deur lipase-aktiwiteit oor 'n sewe-dag periode te monitor. Die geselekteerde rasse is ook getoets vir lipase-aktiwiteit met p-nitrofenielpalmitaat. Ophiostoma piliferum Cartapip 58™ en Phanerochaete chrysosporium BKM-F-1767, twee rasse wat daarvoor bekend staan vir onderskeidelik hul vermoë om houtekstrakstowwe te verminder en te bioverpulp, is as kontroles gebruik. 'n Paar van die geselekteerde rasse het goed vergelyk en selfs beter presteer as die kontrolerasse; 'n aanduiding van hul potensiaal om neerslagreaksies te beheer. Die effek van voorafbehandeling met die agt geselekteerde fungi rasse op E. grandis hout- en pulpekstrak is vasgestel. Cartapip 58™ en P. chrysosporium BKM-F-1767 is gebruik as kontrolerasse. Verskeie rasse het goed vergelyk met die kontrolerasse in hul vermoë om die trigliseriedinhoud van die houtekstrak te verlaag. Die Suid-Afrikaanse isolaat, witverrottingswam Phanerochaete pseudomagnoliae nom. prov., het ook die trigliseried inhoud beduidend verminder. Gevolglik sou dit as 'n middel kon dien vir beide neerslagvoorkoming en bioverpulping. Die trigliseriedinhoud van die behandelde monsters was laer as dié van steriele kontroles. Gevolglik sal meer trigliseriede in proseswater vrygestel word deur die steriele kontroles as die behandelde monsters. Die effek van kommersiële lipases op ongebleikte kraft pulpekstrakneerslag is ook geëvalueer. Omdat lipases nie die trigliseriedinhoud van die neerslag kon verlaag nie sal die gebruik van lipases dus nie die ekstrakstofneerslag in verpulpings- en bleikingsprosesse beïnvloed nie.

Graduation date: 1999

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