This work concerns the efficient treatment of wastewaters from pulp and paper mills by means of aerobic biological processes. For treatment processes there are many aspects of efficiency and the present study investigates both energy efficiency and purification efficiency during disturbances. Special focus is put on wood extractives, such as resin acids and fatty acids, since they can cause negative effects in fish and other organisms in the receiving waters. They can furthermore be toxic to microorganisms in a biological treatment plant. They also affect oxygen transfer, which is important for energy efficient aeration of aerobic biological treatment processes. This thesis includes five papers/studies and presents a strategy for efficient treatment of forest industrial wastewaters. The results should help creating resilient wastewater treatment strategies with efficient use of energy. One new strategy proposed here includes separation of extractives before the wastewater is treated biologically, and the use of the extra amount of sludge as an energy source, shifting the energy balance from negative to positive.

During kraft cooking a significant part of the wood material, especially lignin and hemicelluloses, is degraded and dissolved in the cooking liquor, rendering a broad range of degradation products with different molecular mass and functional groups. The main part of this thesis has been devoted to clarify the role of these dissolved wood components (DWC) during kraft cooking. The investigations have covered their influence on e.g. the delignification rate, pulp yield, point of defibration, unbleached pulp c olour and pulp bleachability, i.e. the amount of bleaching chemicals consumed per kappa number or lignin unit to reach a certain brightness. Both softwood (Picea Abies) and hardwood (Eucalyptus urograndis) have been studied. During kraft cooking, many reactions occur simultaneously. Therefore emphasis has been put on separating the effects of hydroxide ions, hydrogen sulphide ions, sodium ions and DWC. This has been enabled by the use of a so called constant-composition-cooking technique, which enables the use of almost constant concentrations of the cooking chemicals during the cook and also results in a very low concentration of DWC in the cooking liquor. The presence of DWC has been controlled by the addition of industrial black liquor. To further scrutinise the role of DWC, the effect of different molecular mass fractions were studied and representative model substances were used to clarify the origin of the observed effects. A kinetic study showed that the delignification rate was significantly affected by the presence of DWC in the cooking liquor and resulted in a rate increase in the part of the cook where the bulk phase dominates and a decreased delignification rate when the residual phase dominates. The increase in delignification rate was dependent on the concentration of DWC and was observed in softwood as well as hardwood kraft cooks. The rate increasing effect was investigated further by the use of ultra- and nanofiltra tion. This way the DWC was divided into fractions with different molecular mass distributions. The results showed that the increase in delignification rate related more strongly to the content of free phenolic groups in the DWC than on the total amount of DWC. By cooking in the presence of representative model substances the effect was further clarified. Aromatic structures with free phenolic groups gave a rate increasing effect while no visible effect could be seen from other structures. This supports the finding that the delignification rate relates to the amount of free phenols in the cooking liquor and shows that the phenolic functionality take active part in the delignification reactions. Free phenolic groups in the degraded lignin may explain a large part of the rate increasing effect seen from the presence of DWC. Further, the presence of DWC increased the point of defibration in a eucalyptus kraft cook and made it possible to terminate the cook at a higher kappa number with the same amount of reject. By terminating the cook at a higher kappa number it was possible to noticeably increase the fully bleached pulp yield. The content of hexenuronic acids (HexA) in the eucalyptus pulp depends on the H-factor and increases with delignification, providing that the bulk phase still dominates. Therefore, by increasing the rat e of delignification and terminating the cook at a higher kappa number it was possible to significantly decrease the amount of HexA in the pulp. The presence of DWC causes a darkening of the unbleached pulp. Bleachability in a D(EOP)DD sequence was negatively affected by the presence of DWC during pulping of softwood, while no effect was seen on the bleachability of hardwood / QC 20100920

This work focuses on high-temperature kraft black liquor gasification in the presence of H2O and CO2 in a laboratory-scale Laminar Entrained-Flow Reactor (LEFR). The effects of gasification conditions on hydroxide formation, carbon gasification rate, carbonate carbon and fixed carbon levels, alkali metal and sulfur species retention, and char yield were studied at atmospheric pressure and at 900-1000oC, and at residence times of 0.5-1.5 s. The results suggest that carbon gasification rates may be enhanced in the presence of H2O and CO2, with fixed carbon conversions of up to 95% at the earliest residence times at 1000oC. CO2 and H2O gasifying agents cause a significant increase in carbonate formation, with 22% of the initial carbon input forming carbonate as compared to 16% with one gasifying agent. Carbonate levels increase to a maximum level and then decrease at 900oC, but at 1000oC, carbonate decomposition processes are more dominant and cause lower levels of carbonate even at early residence times. The results show that alkali metal retention is high until vaporization occurs after 1.4 s at 900oC and at early residence times at 1000oC. Moreover, the results indicate that sulfur retention is an exothermic process, as sulfur capture increases with temperature. At 900oC, no hydroxide is produced until after 1.4 s, but at 1000oC, hydroxide appears to form readily even at the earliest residence times studied. The char product yields a maximum mole percent of 18-19% hydroxide, starting at intermediate residence times at 1000oC. Generally, hydroxide is not produced until fixed carbon conversions approach 95%. The results can be explained in terms of the interactions of phenolate and carboxylate catalytic moieties in the char product. The hydroxide formation results suggest that it may be possible to develop a gasification-causticization process that does not require external chemicals and would make the energy-efficient and environmentally friendly black liquor gasification technology an economic reality.

The increased use of fossil fuels during the last centuries has caused elevated levels of carbon dioxide in the atmosphere. There is significant evidence that this is the cause of global warming. To mitigate the global warming, measures has to be taken to use renewable fuels and make processes more efficient. Catalytic gasification and downstream upgrading of synthesis gas is a promising technology for biofuel production, where previous research in black liquor gasification is currently expanding into a wider fuel feedstock. This work focuses on co-gasification of black liquor and by-products from other biofuel production technologies. The interesting by-products were crude glycerol from biodiesel production and spruce fermentation residue from ethanol production. The main goals were to study if the fuels can mix homogeneously and study the char reactivity. CO2 char gasification for mixtures of black liquor and glycerol or fermentation residue respectively was studied using thermogravimetric analysis (TGA) for four temperatures between 750°C and 900°C. The results show that glycerol can be mixed in all proportions with black liquor and indicate that the char reactivity is unchanged. The sustained char reactivity for blends is attributed to the volatility of glycerol. The fermentation residue does not produce a homogeneous mixture with black liquor and the char is less reactive. More studies should be performed to further elucidate the validity of the results.

Dans ce travail, la lignine extraite de la liqueur noire a été d'abord caractérisée et ensuite valorisé selon deux approches différentes: (i) une utilisation après une modification chimique pour la synthèse des mousses de polyuréthane et (ii) une pyrolyse simple pour fabriquer le charbon. En effet, une étude comparative concernant la caractérisation des fonctions hydroxyl a été réalisée en utilisant plusieurs méthodes et techniques, notamment, la titration et la spectroscopie RMN du 13C. Dans la première approche, la lignine a été convertie en polyols liquides grâce à une réaction d'extension de chaîne avec l'oxyde de propylène (oxypropylation). Les formulations des polyols ont été optimisées, en inspectant l'effet de différents paramètres : lignine/oxyde de propylène, le taux de catalyseur, la masse moléculaire, l'indice d'hydroxyle, la viscosité et la température de transition vitreuse. Les indices d'hydroxyles et la viscosité des polyols produits ont été caractérisés. Les mousses rigides de polyuréthane ont été évaluées en termes de densité, de morphologie et de propriétés mécaniques. La lignine a ensuite été utilisée comme précurseur de charbon sans aucun traitement d'activation et a été comparée avec le charbon commercial. Une étude cinétique d'adsorption a été réalisée et montré que l'équilibre d'adsorption est atteint au bout de 50 min, en suivant un modèle de pseudo-premier ordre. L'étude des isothermes d'adsorption a révélé que le CL retient efficacement les ions métalliques, et présente une capacité d'adsorption maximale entre 200 et 400 µmol/g pour des concentrations très inférieure à 20ppm. Le charbon obtenu après saturation en ions métalliques, a été régénéré efficacement par lavage avec une solution d'EDTA ou une solution d'acide nitrique.De plus, les deux approches d'utilisation de la lignine extraite de la liqueur noire d'alfa ont donnée des matériaux avec des propriétés prometteuses. Dans la majorité des cas, des matériaux avec des propriétés similaires à celles des matériaux conventionnels, ce qui présente une option viable d'une valorisation rationnelle de déchet industriel abondant et provenant d'une source renouvelable. / Lignin precipitated from black liquor of alfa (Stipa tenacissima) soda cooking before being carefully characterized and valorized following two different approaches: (i) its utilization after chemical modification in view of preparing rigid polyurethane foams; and (ii) its simple pyrolysis simple, in order to prepare charcoal. In fact, a comparative study concerning the careful characterization of the hydroxyl functions was realized using several methods and techniques, namely: the conductimetric titration and 13C-NMR spectroscopy. In the first approach, the precipitated lignin was converted in liquid polyols thanks to a chain-extension reaction with propylene oxide. These formulations were optimized by inspecting the effect of different parameters: lignin/propylene oxide ratio, the amount of catalyst, the molecular weight of the prepared polyols, the hydroxyl index and the glass transition temperature. The hydroxyl indexes and the viscosity of the prepared polyols were determined. The rigid polyurethane foams were studied in terms of their density, morphology and mechanical properties. The lignin was then used as a precursor for the preparation of charcoal without any activation treatment and compared with commercial homologue. The kinetic of the adsorption was performed and showed that the adsorption equilibrium is reached at about 50 min, and followed a pseudo-first order kinetic model. The adsorption isotherms revealed that lignin-based charcoal retained efficiently the metallic ions and presented a maximum adsorption capacity varying from 200 to 400 µmol/g. This is true even for concentrations much lower than 20 ppm. Le saturated lignin-based charcoal was efficiently regenerated by washing with solutions of EDTA or a nitric acid.The two approaches of the valorization of lignin precipitated from black liquor gave materials with promising properties. Thus, in the majority of cases, materials with properties similar to conventional ones were obtained, which presents a viable option of rational valorization of this industrial abundant and renewable by-product.

L’atelier de régénération d’une usine kraft permet d’extraire des liqueurs noires les élémentschimiques nécessaires à la cuisson du bois et de les régénérer sous leur forme active, ainsi quede valoriser la fraction organique dissoute sous forme de chaleur. Les opérations unitaires enoeuvre sont nombreuses, complexes, et souvent mal décrites. Ce travail vise à permettre unemeilleure compréhension de la régénération, par la réalisation de modèles fiables décrivant lesphénomènes et processus dans chaque opération unitaire, leur implémentation algorithmiqueet leur exploitation par la simulation du procédé global. / Chemical recovery at the kraft mill is the process whereby the valuable inorganic elements areextracted from spent kraft liquors and regenerated under their form effective to the cooking ofthe wood and energy is producted from the dissolved organic fraction. Many unit operations areinvolved, often poorly described. This work aims at a better understanding of the recovery processes.Reliable models describing the physical phenomena were proposed for each operation andimplemented as a computer algorithm. The whole chemical recovery unit was then simulated.

Made available in DSpace on 2014-06-11T19:23:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-08-02Bitstream added on 2014-06-13T20:30:11Z : No. of bitstreams: 1 carrion_lm_me_sjrp.pdf: 381584 bytes, checksum: f7ac95eb0ed933b2a92b058b0e3faefb (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A efetiva produção de etanol lignocelulósico depende de leveduras capazes de fermentar a fração hemicelulósica da biomassa lignocelulósica que é composta em sua maioria por xilose. Há uma grande dificuldade em encontrar esses microrganismos já que a capacidade de utilizar xilose como fonte de carbono não é apresentada pela maioria das leveduras. Neste trabalho leveduras isoladas de diferentes materiais da zona rural,foram testadas quanto à assimilação de xilose e glicose, e fermentação de xilose a 30°C, onde observou-se diferentes comportamentos entre diferentes linhagens da mesma espécie. As linhagens de leveduras isoladas foram identificadas pela técnica molecular PCR-RFLP empregando-se as regiôes ITS 5,8 S e D1/D2 do DNA ribossômico. Três leveduras identificadas como espécies de Cândida tropicalis foram avaliadas quanto a capacidade de produção de xilitol e etanol a partir de meio basal com xilose como única fonte de carbono e do licor negro da extração da celulose hidrolisado por enzimas do fungo Thermoascus aurantiacus. A produção de xilitol foi semelhante nos dois substratos, entretanto a produção de etanol foi maior quando o licor negro foi empregado, esses resultados mostraram que a quantidade e a natureza dos açúcares presentes nos meios foram um interferente maior no metabolismo da levedura que os compostos tóxicos presentes no licor negro / The effective lignocellulosic ethanol production depends on yeasts that are able to ferment the hemicellulosic biomass fraction, which is mostly composed by xylose. There is a big difficulty in finding such microorganisms because most yeasts do not use xylose as a carbon source. In this work, yeasts isolated from different materials were tested for xylose and glucose assimilation and xylose fermentation at 30°C ,where it was observed different behaviors between strains of the same species. The strains isolated were identified by PCR-RFLP molecular technique employing the ITS 5,8 and D1/D2 regions of ribosomal DNA. Three yeasts were identified as Cândida tropicalis species and their ability to produce xylitol and ethanol from xylose and the black liquor from the cellulose extraction hydrolyzed by enzymes of the fungus Thermoascus aurantiacus was evaluated. The xylitol production was similar in both media, but the ethanol production was higher when the black liquor was used, these results shows that the quantity and nature of the sugars present in the media have a bigger interference in the metabolism of yeast to toxic compounds present in black liquor

O aumento da conscientização ecológica, observado nos últimos anos, levou às indústrias investirem em alguns sistemas de produção tecnologicamente menos impactantes ao meio ambiente, como é o caso das biorrefinarias. No setor de celulose e papel as indústrias podem ser consideradas como biorrefinarias pois produzem bioenergia e bioprodutos a partir da utilização da biomassa, tais como energia elétrica e polpa celulósica. No processo de polpação kraft, obtém-se o licor negro o qual contém compostos orgânicos e inorgânicos provenientes da matéria prima e dos reagentes químicos e aditivos utilizados no processo. Com isso, o licor negro contém além da lignina dissolvida da madeira, alguns subprodutos formados em reações específicas e que podem ser recuperados, destacando-se entre esses o metanol, o qual pode chegar a compor 1% do licor negro. O metanol celulósico extraído na etapa de tratamento de condensado contaminado contém diversos compostos noviços ao meio ambiente e por este motivo o metanol celulósico é utilizado como combustível, sendo incinerado para geração de energia e para redução dos contaminantes a formas menos nocivas ao meio ambiente. Assim, obter o metanol celulósico significa purificá-lo para que possa ser aplicado para outros fins mais nobre, como por exemplo, aplicado como reagente nas indústrias químicas. Com isso, o presente estudo teve por objetivo avaliar o potencial de operação de uma unidade de recuperação e de purificação de metanol celulósico acoplado a uma moderna unidade de produção de polpa celulósica. Para isso, foram realizadas visitas técnicas à unidade industrial e efetuada uma ampla revisão bibliográfica do processo de evaporação de licor negro e de formação dos compostos presentes no metanol celulósico de forma a definir as condições e métodos de modelagem e simulação mais apropriados para o desenvolvimento desta dissertação. O estudo foi divido em duas etapas, sendo que a primeira consistiu na utilização do simulador comercial WinGEMS® para construção de um modelo computacional de uma unidade de evaporação de licor negro, o qual mostrou-se adequado para a determinada aplicação através de validações comparativas entre os resultados da simulação com valores reais de operação. Na sequência, desenvolveu-se um modelo computacional para o planejamento de uma unidade de obtenção e purificação de metanol celulósico via software Aspen Plus® sendo acoplado ao modelo anterior. Em síntese, a metodologia aplicada mostrou-se satisfatória para o presente estudo sendo possível simular com propriedade uma unidade de evaporação de licor negro e avaliar o impacto industrial de se acoplar uma unidade de purificação de metanol celulósico a indústria celulósica, no que tange a dimensionamentos de equipamentos, quantificação dos insumos e eficiência de purificação de metanol celulósico. / The increase in ecological awareness observed in recent years has led industries to invest in some production systems technologically less harmful to the environment, such as biorefineries. The industries form the pulp and paper sector, can be considered as biorefineries because they produce bioenergy and bioproducts from the use of biomassa, such as electric power and cellulosic pulp. In the kraft pulping process, the black liquor is obtained, wich contains organic and inorganic compounds from the raw material and from the chemicals reagents and additives used in the process. Black liquor contains, in addition to the dissolved lignin of the wood, some by-products formed in specific reactions and that can be recovered, among them methanol, which can make up 1% of the black liquor. The cellulosic methanol extracted in the treatment stage of contaminated condensate contains several compounds that are harmful to the environment and for this reason the cellulosic methanol is used as fuel, being incinerated for energy generation and for the reduction of contaminants to forms less harmful to the environment. Thus, obtaining the cellulosic methanol means purifying it so that it can be applied to other, more noble purposes, for example, as a reagent in the chemical industry. The aim of this study was to evaluate the potential of a cellulosic methanol recovery and purification unit coupled to a modern cellulosic pulp production unit. Technical visits were made to the industrial unit and a vast bibliographical review of the process of evaporation of black liquor and formation of the compounds present in the cellulosic methanol was carried out in order to define the conditions and the most appropriate modeling and simulation methods for the development of this dissertation. The study was divided in two stages, the first one consisted of the use of the WinGEMS® commercial simulator to construct a computational model of a black liquor evaporation unit, which proved to be suitable for the given application through comparative validations between simulation results with actual operating values. In the sequence, a computational model was developed for the planning of a cellulosic methanol purification and purification unit using Aspen Plus® software being coupled to the previous model. In summary, the applied methodology proved to be satisfactory for the present study, being it possible to properly simulate a black liquor evaporation unit and to evaluate the industrial impact of coupling a cellulosic methanol purification unit to the cellulosic industry, in terms of equipment design, input quantification and cellulosic methanol purification.

O licor negro, cuja composição majoritária é de lignina, é o principal subproduto gerado após a obtenção de polpa celulósica. Este polímero natural é caracterizado pela elevada massa molecular (MM) e composição aromática. Processos físico-químicos são empregados na fragmentação da lignina com o objetivo de obter compostos aromáticos, cuja fonte não renovável é oriunda de derivados do petróleo. A biodegradação da lignina, causada pela ação de enzimas ligninolíticas fúngicas pode prover compostos aromáticos de baixo peso molecular, como fenóis e antioxidantes, utilizados em diversos segmentos industriais. O objetivo deste trabalho foi estudar a modificação estrutural da lignina causada por fungos basidiomicetos coletados de mata nativa e campos de reflorestamento de eucalipto. Os ensaios de biodegradação foram inicialmente conduzidos utilizando-se 10 espécies de fungos, cultivados em duas concentrações de licor negro (10% e 15%, v/v). No ensaio com licor menos concentrado, utilizaram-se 10 espécies, e no ensaio com licor 15% utilizou-se somente a espécie Pycnoporus sanguineus. As análises realizadas para o estudo da modificação estrutural da lignina foram: espectroscopia na região do infravermelho (FTIR/ATR), cromatografia líquida de gel filtração e espalhamento de raios-X a baixo ângulo (SAXS). P. sanguineus e espécies de fungos do gênero Trametes possuem elevada capacidade de consumir a lignina presente no licor 10%, após 14 dias. A atividade de enzimas ligninolíticas de P. sanguineus foi investigada nas duas concentrações de licor. No licor 10%, observou-se elevada atividade das enzimas ligninolíticas manganês peroxidase (MnP), lacase e peroxidases; somente a MnP foi detectada com maior atividade no licor 15%. Análises de Demanda Bioquímica de Oxigênio (DBO) indicaram que o licor negro 10% biodegradado por P. sanguineus possui elevada carga de DBO, sendo tóxico a Daphia magna e Hydra attenuatta. Análises de metabólitos produzidos pelos fungos no licor negro 10% por cromatografia gasosa acoplada à espectrometria de massas (GC-MS) indicaram, principalmente, a produção de açúcares e álcoois em concentrações não muito diferentes dos seus respectivos controles. Embora os fungos sejam capazes de reduzir a massa molecular da lignina presente no licor negro, compostos derivados da sua fragmentação podem sofrer reações de condensação ou repolimerização, contribuindo, eventualmente, para elevar sua massa molecular / Black liquor which the bulk content is lignin, is the main product generated after obtaining cellulose pulp. This natural polymer is characterized by high molecular weight (MW) and aromatic compounds. Physical-chemical processes can be employed to fragment lignin and to produce aromatic compounds to replace those from non-renewable sources such as petroleum. Biodegradation of lignin can provide low molecular weight compounds, such as phenols and antioxidants, which may be employed in various industrial processes. The aim of this work was to investigate the structural modification of lignin caused by basidiomycetes fungi, obtained from native forest and Eucalyptus fields. The biodegradation assay was done with10 fungi species cultivated with two concentrations of black licor (10% and 15%, v/v). The assay with 10% liquor, 10 species of basidiomycete fungi were used, and in the assay with 15% liquor, it was used only Pycnoporus sanguineus. The analyses carried out to determine the structural modification of lignin were: infrared spectroscopy (FTIR/ATR), liquid chromatography gel filtration and small angle X-ray scattering (SAXS). P. sanguineus and fungi of Trametes genera had high capacity to consume the lignin content in the 10% liquor, after 14 days of cultivation. After that, P. sanguineus was selected for assays of ligninolytic enzymes activities in the two liquor concentrations. High activities of manganese peroxidase (MnP), laccase and peroxidase were detected in the 10% liquor, whereas in the concentration of 15% only high MnP activity was detected. Biochemical Oxygen Demand, analysis (BOD) indicated that the biodegraded liquor had high BOD load, and it was toxic to Daphia magna and Hydra attenuata. Metabolites produced by the fungi in the liquor 10% were analysed by gas chromatography-mass spectrometry (GC-MS), which indicated mainly the production of sugars and alcohols in concentrations not far from their respective controls. Although the fungus is able to decrease molecular weight of lignin, its fragments derivatives can undergo condensation or repolymerization reactions, contributing, eventually, to increase its molecular weight

Orientador: José Vicente Hallak d'Angelo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-21T11:05:01Z (GMT). No. of bitstreams: 1 Marins_Gabrielde_M.pdf: 4193921 bytes, checksum: e80672b42613eddad46d14b2c94e31c8 (MD5) Previous issue date: 2012 / Resumo: No processo Kraft para produção de papel e celulose, os cavacos de madeira são cozidos em um digestor com uma solução aquosa denominada licor branco, constituída de hidróxido de sódio (NaOH) e sulfeto de sódio (Na2S). Durante o cozimento uma pasta fibrosa é produzida. Esta pasta é filtrada e segue para o branqueamento. O produto filtrado chama-se licor negro, devido à mudança da sua cor nesta etapa. O licor negro possui aproximadamente 15 % de sólidos em massa. Ele é bombeado para a unidade de recuperação, na qual ele será concentrado em evaporadores de múltiplosefeitos até 75 % de sólidos em massa. Em seguida, ele é bombeado para uma caldeira onde é queimado, para recuperar os sais inorgânicos e, principalmente, fornecer calor para geração de calor. Durante a evaporação do licor negro, quando a porcentagem em sólidos ultrapassa 50 %, ocorre a precipitação de sais inorgânicos. Estes sais se depositam nas superfícies de troca térmica dos evaporadores diminuindo sua eficiência e causando prejuízos à indústria. Os principais sais que causam este problema são o carbonato de sódio (Na2CO3) e o sulfato de sódio (Na2SO4). O objetivo do presente trabalho foi testar e validar um método experimental para a determinação da quantidade de Na2CO3 presente em amostras industriais de licor negro. Além disso, também foram analisadas algumas propriedades físico-químicas do licor negro, como massa específica, teor de sólidos e viscosidade. Com os resultados obtidos, tentou-se obter uma correlação entre o teor de carbonato de sódio e as demais propriedades do licor que foram determinadas. Os resultados das análises das características físico-químicas demonstraram coerência e boa reprodutibilidade, porém, os resultados das análises de teor de carbonato de sódio não foram satisfatórios e mostraram que a técnica deve ser aperfeiçoada / Abstract: In the Kraft process for pulp and paper production, wood chips are cooked in a digester with an aqueous solution named white liquor, consisted by sodium hydroxide (NaOH) and sodium sulfide (Na2S). During this cooking process, wood chips are transformed generating a fibrous paste and a liquid solution. This paste is filtered and separated from the liquid solution, named black liquor due to its color. The paste goes to the bleaching stage to produce cellulose. Black liquor contains inorganic and organic (mainly lignin) compounds from wood. Initially this black liquor contains approximately 15 mass/% of solids and is sent to the recovery unit to have this concentration raised to approximately 75 mass/% to be burned in a recovery boiler in order to generate power and recover inorganic reactants, recycling them to the process. The concentration process of black liquor occurs in a multiple effect evaporators unit. During this process, when the concentration of solids exceeds 50%, the precipitation of inorganic salts (mainly Na2CO3 and Na2SO4) begins. These salts are deposited in the heat transfer surfaces of the evaporator tubes, reducing their efficiency, leading to a reduction in the production capacity. The scope of this work was testing and validate an experimental method to estimate the content of Na2CO3 present in industrial black liquor samples. Moreover, some black liquor's physical-chemical properties as density, solids content and viscosity were also analyzed. An attempt to develop a predictive model to evaluate sodium carbonate content from the other properties was made. The results obtained for physical-chemical properties have shown a good consistency. However, the results of sodium carbonate analyses were not satisfactory, showing that the technique must be improved / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química