Thesis (M.S. - Civil Engineering and Engineering Mechanics)--University of Arizona, 1986. / Includes bibliographical references (leaves 81-82).

Thesis (M.S.)--Virginia Polytechnic Institute, 1961. / Vita. Abstract. Includes bibliographical references (leaves 83-89). Also available via the Internet.

Thesis (Ph. D.)--University of Washington, 1991. / Vita. Includes bibliographical references (leaves [102]-109).

O presente trabalho teve por objetivo estudar a influência da carga alcalina no processo de polpação kraft modificado Lo-SolidsÒ para madeiras de eucalipto, considerando parâmetros como rendimento, teor de rejeitos, geração de sólidos e características da polpa tais como número kappa, viscosidade, composição polissacarídica e morfologia de fibras. Híbridos de E. grandis x E. urophylla com 7 anos e densidade básica de 500 e 560kg/m 3 foram avaliados e os cozimentos Lo-Solidsâ foram realizadas aplicando-se álcali ativo (como Na2O) de 13%, 15%, 17%, 19%, 21%, 23%, 25%, 27% e sulfidez de 30%. O delineamento experimental adotado foi o inteiramente casualizado. Os resultados obtidos indicam que variando a carga alcalina no processo de polpação é possível obter polpa não branqueada apresentando valores de kappa de 8 a 30, rendimento depurado de 46 a 53%, viscosidade de 10 a 80 cP, solubilidade em NaOH 5% (S5) de 7 a 13%, teor de pentosanas de 11 a 16% e ácidos hexenurônicos de 10 a 65 µ mol/g. O aumento da carga alcalina nos cozimentos proporcionou maior geração de finos e, consequentemente, menor comprimento médio ponderado de fibras e espessura de parede. Embora os materiais estudados apresentassem diferentes densidade básica, os resultados de polpação foram semelhantes indicando que ambas matérias-primas podem ser empregadas na obtenção de polpa celulósica utilizando o processo de cozimento Lo-Solids®, o qual não se mostrou sensível a densidade básica, o que possivelmente está associado a boa impregnação dos cavacos correspondente à etapa de impregnação. O híbrido de maior densidade produziu polpa com fibras de maior espessura de parede, maior coarseness e menor número de fibras por grama que o híbrido de menor densidade básica. As análises do licor negro mostraram que o de pH, o álcali efetivo residual e o teor de sólidos dissolvidos apresentam maiores valores para dosagens de álcali também superiores, porém observa-se um perfil uniforme para essas variáveis, evidenciando a homogeneidade do processo de polpação Lo-SolidsÒ. / The main objective of this work was to study the influence of the alkali charge on Lo-Solidsâ modified kraft pulping process for eucalyptus, considering parameters as yield, rejects content, total dissolved solids materials and the pulp characteristics as kappa number, viscosity, carbohydrate composition and fibers dimensions. Woods from hybrids of Eucalyptus grandis x Eucalyptus urophylla 7 years old and presented basic density of 0,499 and 0,559g/cm 3 were evaluated and the pulping process was conducted applying active alkali charge (as Na2O) of 13%, 15%, 17%, 19%, 21%, 23%, 24%, 25%, 27% and sulfidity of 30%. The results showed that varying the alkali charge is possible to obtain unbleached pulp with kappa number from 8 to 30, pulp yield from 46 to 53%, viscosity from 10 to 80cP, alkali solubility (S5) from 7 to 13%, pentosans content from 11 to 16% and hexenuronic acids content from 10 to 65µmol/g. It was verified that the higher is the alkali charge the higher is the fines generation leading to a decreased of fiber length and the cell wall thickness. Although the hybrids studied presented different wood basic density, the pulping results obtained were not different showing that both raw-materials could be used to pulp production with Lo-SolidsÒ pulping process, which seems not to be so affect by wood basic density. The pulp obtained from hybrid with higher basic density showed higher cell wall thickness, higher fiber coarseness and lower number of fibers per gram than the hybrid with lower basic density. The analysis of black liquor showed that the pH, the effective residual alkali and the total dissolved solids materials increased when the alkali charge applied is higher too, however a uniform profile is noted for these variables, showing the homogeneity of Lo-SolidsÒ pulping process.

The Swedish pulp and paper industry is the third largest exporter of pulp and paper products worldwide. It is a highly energy-demanding and water-utilising industry, which generates large volumes of wastewater rich in organic material. These organic materials are to different extents suitable for anaerobic digestion (AD) and production of energy-rich biomethane. The implementation of an AD process within the wastewater treatment plant of a mill would increase the treatment capacity and decrease the overall energy consumption due to less aeration and lower sludge production and in addition produce biomethane. Despite the many benefits of AD it is only applied at two mills in Sweden today. The reason for the low implementation over the years may be due to problems encountered linked to the complexity and varying composition of the wastewaters. Due to changes in market demands many mills have broadened their product portfolios and turned towards more refined products. This has increased both the complexity and the variations of the wastewaters´ composition even further, as the above changes can imply an increased pulp bleaching and utilisation of more diverse raw materials within the mills. The main aim of this thesis was therefore to generate knowledge needed for an expansion of the biomethane production within the pulp and paper industry. As a first step to achieve this an evaluation of the biomethane potential and the suitability for AD of wastewaters within a range of Swedish pulp and paper mills was performed. Thus, around 70 wastewater streams from 11 different processes at eight mills were screened for their biomethane potential. In a second step, the impact of shifts in wood raw material and bleaching on the AD process and the biomethane production was investigated and further evaluated in upflow anaerobic sludge bed (UASB) reactors. The screening showed that the biomethane potential within the Swedish pulp and paper industry could be estimated to 700 GWh, which corresponds to 40% of the Swedish biomethane production during 2014. However, depending on the conditions at each specific mill the strategy for the establishment of AD needs to differ. For mills producing kraft pulp the potential is mainly found in wastewaters rich in fibres, alkaline kraft bleaching wastewaters and methanol-rich condensates. The biomethane potential within thermo-mechanical pulp- (TMP) and chemical thermo-mechanical pulp (CTMP) mills is mainly present in the total effluents after pre-sedimentation and in the bleaching effluents as these holds high concentrations of dissolved organic material. The screening further showed that the raw material used for pulp production is an important factor for the biomethane potential of a specific wastewater stream, i.e. hardwood (HW) wastewaters have higher potentials than those from softwood (SW) pulp production. This was confirmed in the lab-scale UASB reactor experiments, in which an alkaline kraft bleaching wastewater and a composite pulping and bleaching CTMP wastewater were used as substrates. AD processes were developed and maintained stable throughout shifts in wastewater composition related to changes in the wood raw materials between SW and HW for the kraft wastewater and spruce, aspen and birch for the CTMP wastewater. The lower biomethane production from SW- compared to HW wastewaters was due to a lower degradability together with a higher ratio of sulphuric compounds per TOC for the SW case. The impact of shifts between bleached and unbleached CTMP production could not be fully  evaluated in the continuous process mainly due to technical problems. However, due to the large increase in dissolved organic material when bleaching is applied, the potential biomethane production will increase during the production of bleached pulp compared to unbleached pulp. Based on the biomethane potentials obtained for one of the included CTMP mills, their yearly production of biomethane was estimated to 5-27 GWh with the lowest and the highest value corresponding to the production of unbleached spruce pulp vs. bleached birch pulp. Thus, the results of the investigations presented in this thesis show that the UASBreactor is suitable for AD of wastewaters within the pulp and paper industry. The results also show that challenges related to variations in the organic material composition of the wastewaters due to variations in wood raw materials could be managed. The outcome of the thesis work also imply that the production of more refined products, which may include the introduction of an increased number of raw materials and extended bleaching protocols, could increase the potential biomethane production, especially if the pulp production will make use of more HW. / Den svenska pappers- och massaindustrin är den tredje största exportören av massa och pappersprodukter och en viktig industriell aktör i Sverige. Det är en industri med hög energi- och vattenanvändning, som genererar stora mängder avloppsvatten rika på organiskt material. Detta organiska material kan via anaerob nedbrytning användas för att producera energirik biometan. Användandet av anaerob behandling, som ett steg i brukens vattenrening, genererar inte bara biometan utan kan också öka reningskapaciteten och minska energiförbrukning och kostnader tack vare minskat behov av luftning och minskad slamproduktion. Trots de många fördelarna med anaerob behandling är den idag bara tillämpad på två bruk i Sverige. En av orsakerna till detta kan vara processproblem som relaterats till avloppsvattnens komplexitet samt varierande sammansättning och flöden. Många pappers- och massabruk har utökat sina produktportföljer med bl a mer förfinade produkter, som en följd av en förändrad marknad. Dessa förändringar har ökat avloppsvattnens komplexitet och variation än mer, då ovan exempelvis kan medföra en ökad produktion av blekt massa samt att fler typer av träråvaror används vid ett och samma bruk. Huvudsyftet med föreliggande avhandling är att bidra med kunskap för en ökad produktion av biometan inom pappers- och massaindustrin. Som ett första steg genomfördes en övergripande utvärdering av ca 70 avloppsvattenströmmar från totalt 11 olika processer vid åtta svenska pappers- och massabruk med fokus på biometanpotential samt lämplighet för anaerob behandling. I ett andra steg utvärderades hur skiften i träråvara samt blekning påverkar biometanproduktionen samt processtabiliteten för en kontinuerlig anaerob nedbrytningsprocess i en UASBreaktor. Den initiala utvärderingen visade att den svenska pappers- och massaindustrin skulle kunna bidra med 700 GWh biometan per år, vilket motsvarar 40% av biometanproduktionen i Sverige under 2014. Beroende på utformningen av det enskilda bruket kommer strategier för implementering av anaeroba processer att se olika ut. För bruk som producerar sulfatmassa återfanns huvuddelen av biometanpotentialen i fiberrika avloppsvattenstömmar, alkaliska blekeriavlopp samt metanolrika kondensat. För bruk som producerar termomekanisk- (TMP) eller kemitermomekanisk (CTMP) massa föreligger biometanpotentialen framförallt i avloppsvatten rika på löst organiskt material såsom totalavlopp efter sedimentering och blekeriavlopp. Den initiala utvärderingen visade också att användandet av lövved ger en högre biometanpotential jämfört med barrved. Dessa resultat kunde bekräftas vid kontinuerliga experiment med anaerob nedbrytning i UASB-reaktorer, där ett alkaliskt blekeriavlopp från ett sulfatmassabruk och ett kombinerat massaproduktions- och blekeriavlopp från ett CTMP-bruk användes som substrat. Stabila anaeroba processer etablerades och bibehölls vid förändrad avloppsvattensammansättning på grund av skiften i träråvara (löv- och barrved för sulfatmassabruket samt gran, asp och björk för CTMP bruket). Den lägre produktionen av biometan för barrved jämfört med lövved kunde förklaras med en lägre nedbrytbarhet samt ett ökat svavelinnehåll i relation till mängden organiskt material. Skiften mellan avloppsvatten från blekt- och oblekt CTMP massa kunde inte utvärderas fullständigt i den kontinuerliga processen på grund av tekniska problem. Produktionen av blekt massa ökar dock mängden organiskt material i  avloppsvattnet, vilket medför att mer biometan kan produceras jämfört med då oblekt massa produceras. Baserat på biometanpotentialerna för ett av i studien ingående CTMP bruk uppskattas den årliga produktionen av biometan till 5-27 GWh, där den lägsta produktionen motsvarar oblekt granmassa och den högsta produktionen motsvarar blekt björkmassa. Sammanfattningsvis visar studien att UASB-reaktorer är lämpliga för anaerob behandling av avloppsvatten inom pappers- och massaindustrin. Vidare visar resultaten från de kontinuerliga försöken att de utmaningar som medförs av den varierande sammansättningen av avloppsvattnens organiska material knutet till träråvaran kan hanteras. Slutligen, breddade produktportföljer samt produktionen av mer förfinade produkter, vilket kan innebära en ökad massablekning och ett ökat användande av olika träråvaror, kan öka brukens potentiella biometanproduktion, särskilt om mer lövved används för massaproduktion.

O presente trabalho teve por objetivo estudar a influência da carga alcalina no processo de polpação kraft modificado Lo-SolidsÒ para madeiras de eucalipto, considerando parâmetros como rendimento, teor de rejeitos, geração de sólidos e características da polpa tais como número kappa, viscosidade, composição polissacarídica e morfologia de fibras. Híbridos de E. grandis x E. urophylla com 7 anos e densidade básica de 500 e 560kg/m 3 foram avaliados e os cozimentos Lo-Solidsâ foram realizadas aplicando-se álcali ativo (como Na2O) de 13%, 15%, 17%, 19%, 21%, 23%, 25%, 27% e sulfidez de 30%. O delineamento experimental adotado foi o inteiramente casualizado. Os resultados obtidos indicam que variando a carga alcalina no processo de polpação é possível obter polpa não branqueada apresentando valores de kappa de 8 a 30, rendimento depurado de 46 a 53%, viscosidade de 10 a 80 cP, solubilidade em NaOH 5% (S5) de 7 a 13%, teor de pentosanas de 11 a 16% e ácidos hexenurônicos de 10 a 65 µ mol/g. O aumento da carga alcalina nos cozimentos proporcionou maior geração de finos e, consequentemente, menor comprimento médio ponderado de fibras e espessura de parede. Embora os materiais estudados apresentassem diferentes densidade básica, os resultados de polpação foram semelhantes indicando que ambas matérias-primas podem ser empregadas na obtenção de polpa celulósica utilizando o processo de cozimento Lo-Solids®, o qual não se mostrou sensível a densidade básica, o que possivelmente está associado a boa impregnação dos cavacos correspondente à etapa de impregnação. O híbrido de maior densidade produziu polpa com fibras de maior espessura de parede, maior coarseness e menor número de fibras por grama que o híbrido de menor densidade básica. As análises do licor negro mostraram que o de pH, o álcali efetivo residual e o teor de sólidos dissolvidos apresentam maiores valores para dosagens de álcali também superiores, porém observa-se um perfil uniforme para essas variáveis, evidenciando a homogeneidade do processo de polpação Lo-SolidsÒ. / The main objective of this work was to study the influence of the alkali charge on Lo-Solidsâ modified kraft pulping process for eucalyptus, considering parameters as yield, rejects content, total dissolved solids materials and the pulp characteristics as kappa number, viscosity, carbohydrate composition and fibers dimensions. Woods from hybrids of Eucalyptus grandis x Eucalyptus urophylla 7 years old and presented basic density of 0,499 and 0,559g/cm 3 were evaluated and the pulping process was conducted applying active alkali charge (as Na2O) of 13%, 15%, 17%, 19%, 21%, 23%, 24%, 25%, 27% and sulfidity of 30%. The results showed that varying the alkali charge is possible to obtain unbleached pulp with kappa number from 8 to 30, pulp yield from 46 to 53%, viscosity from 10 to 80cP, alkali solubility (S5) from 7 to 13%, pentosans content from 11 to 16% and hexenuronic acids content from 10 to 65µmol/g. It was verified that the higher is the alkali charge the higher is the fines generation leading to a decreased of fiber length and the cell wall thickness. Although the hybrids studied presented different wood basic density, the pulping results obtained were not different showing that both raw-materials could be used to pulp production with Lo-SolidsÒ pulping process, which seems not to be so affect by wood basic density. The pulp obtained from hybrid with higher basic density showed higher cell wall thickness, higher fiber coarseness and lower number of fibers per gram than the hybrid with lower basic density. The analysis of black liquor showed that the pH, the effective residual alkali and the total dissolved solids materials increased when the alkali charge applied is higher too, however a uniform profile is noted for these variables, showing the homogeneity of Lo-SolidsÒ pulping process.