Kraft Pulp

With the final aim of reducing the energy consumption and increase the methane production at Swedish pulp and paper mills, the methane potential of 62 wastewater effluents from ten processes at seven pulp and/or paper mills (A-G) was determined in anaerobic batch digestion assays. This mapping is a first step towards an energy efficient and more sustainable utilization of the effluents by anaerobic digestion, and will be followed up by tests in lab-scale and pilot-scale reactors. Five of the mills produce kraft pulp (KP), one thermo-mechanical pulp (TMP), two chemical thermo-mechanical pulp (CTMP) and two neutral sulfite semichemical (NSSC) pulp. Both elemental and total chlorine free (ECF and TCF, respectively) bleaching processes were included. The effluents included material from wood rooms, cooking and oxygen delignification, bleaching (often both acid-and alkali effluents), drying and paper/board machinery as well as total effluents before and after sedimentation. The results from the screening showed a large variation in methane yields (percent of theoretical methane potential assuming 940 NmL CH 4 per g TOC) among the effluents. For the KP-mills, methane yields above 50% were obtained for the cooking effluents from mills D and F, paper machine wastewater from mill D, condensate streams from mills B, E and F and the composite pre-sedimentation effluent from mill D. The acidic ECF-effluents were shown to be the most toxic to the AD-flora and also seemed to have a negative effect on the yields of composite effluents downstream while three of the alkaline ECF-bleaching effluents gave positive methane yields. ECF bleaching streams gave higher methane yields when hardwood was processed. All TCF-bleaching effluents at the KP mills gave similar degradation patterns with final yields of 10-15% of the theoretical methane potential for four of the five effluents. The composite effluents from the two NSSC-processes gave methane yields of 60% of the theoretical potential. The TMP mill (A) gave the best average yield with all 6 effluents ranging 40-65% of the theoretical potential. The three samples from the CTMP process at mill B showed potentials around 40% while three of the six effluents at mill G (CTMP) yielded 45-50%.

This research focused on the production of a novel calcium silicate pigment made from pulverized coal fly ash and its application as a coating pigment in a size press for fiber replacement. Improved specific base paper properties of the newsprint was investigated. This novel coated fly ash based calcium silicate (FACS) pigment and conventional precipitated calcium carbonate (PCC) pigment was applied using a cylindrical laboratory coater. When a 4.3 gsm coat weight of FACS was used during the size press application, the brightness increased 10 points, whereas, when the coat weight of FACS was increased to 7.8 gsm, the brightness increased to 21 points as compared to base newsprint sheet; however, FACS brightness was lower than the PCC coated newsprint sheet. Also, there was a significant gain in other newsprint specific base properties when fly ash based pigment was used. This indicated that it is feasible to utilize a novel fly ash based pigment in the size press coating application...

Lipophilic organic compounds originating from kraft pulping and papermaking were identified by straight gas chromatography/mass spectrometry (CC/MS) analyses. Samples analyzed included a primary clarifier effluent (PE) and a secondary clarifier effluent (SE) from the activated sludge treatment plant of a Finnish ECF-bleached (Elementally Chlorine Free) kraft pulp and paper mill. Liquid-liquid extraction composition of PE was compared with solid phase extraction (SPE) and dialysis of a semipermeable membrane device (SPMD) exposed to PE. Dichloromethane extracts of particulate material isolated from PE, sludges from both the primary and secondary clarifier, a sediment collected in the vicinity of the mill and whitefish subacutely exposed to the secondary treatment effluent were also investigated. Typical pulp mill-related compounds such as terpenes, terpenoids and aromatic compounds were identified in PE whereas these were non-detectable in SE. For example, thunbergene, thunbergol, squalene, longifolene and derivatives of abietic acid were observed in PE. Alkylated polycyclic aromatics were major compounds identified in the sediment sample with retene (C4alkyl phenanthrene) as a predominant component.

The effects of pressurized compressive chip and low dosage sulphite pretreatments were evaluated for production of thermomechanical pulp in mill scale trials using Norway spruce (Picea abies) at the Braviken paper mill (Holmen Paper AB, Sweden). The aim of the study was to provide knowledge leading to the improvement of energy efficiency during the production of mechanical pulps suitable for news and improved new grade papers. Pulps produced in the mill trials were characterized using conventional pulp and paper testing and by advanced methods including image analysis, FTIR with multivariate analysis, Simons staining with statistical analysis, spectral imaging and HCL fibre cleavage. Sulphite pre-treatment gave a linear dose response in tensile index and light scattering with addition of sulphite (≥ 1.2% Na 2 SO 3 ). The maximum in tensile index and light scattering at a sulphur content of 0.2% (as Na 2 SO 3 ) reported previously was not found in this mill study. Low dosage sulphite pre-treatment increased delamination/internal fibrillation of fibres indicating increased fibre flexibility. These fibres produced denser sheets with higher tensile index and slightly reduced light scattering at certain specific energy consumption. The specific energy consumption needed to produce pulp at a certain tensile index was reduced by 320 kWh/BDT (15%) for chips pre-treated with ~1.2% Na 2 SO 3 compared with untreated chips. This gave a reduction in light scattering for sulphite pre-treated pulps when compared at equal tensile index. Image analysis of fibre cross-sections provided information of the composition of the total fibre population, fibre cross-sectional compactness as well as effects of sulphite treatment. Results showed a fairly constant fibre population (40% early-/60% latewood) existing in all samples and for higher energy to cause greater fibre splitting of untreated fibres particularly of latewood fibres. Increasing the amount of sulphite reduced fibre splitting with less severe fibre delamination for pulps refined at 1820 and 1850 KWh/ADT. Sulphite treatment seemed in general to induce more refining of early-than latewood fibres. SEM observation on fibres revealed high degree of deformation along the fibre axis that could also be seen on the fibre crosssections analyzed. FTIR analyses indicated that the highest degree of sulphonation (10 kg/BDT) gave rise to different fibre separation mechanisms during refining compared with the reference unsulphonated pulps providing a different fibre surface and thereby mechanical properties. Multivariate analysis of FTIR spectra suggested the exposed fibre surface to be richer in hemicellulose for sulphonated pulped fibres. This could provide for a better binding surface and higher strength for paper. However, no clear pattern of differences in the distribution images and therefore the microdistribution of xylan were determined. Statistical analysis of the Simons´ staining of fibres indicated that both the energy input and chip pre-treatment significantly induced wall delamination and internal fibrillation (D/IF) of pulp fibres. It was shown that the fibre development of pulp 10(1580) (with lowest SEC) gained via improved wall D/IF was almost similar to that shown for pulp 00(1850) (with highest SEC). This indicates that an energy efficient refining can be obtained with 10 kg/BDT sulfite pre-treatment prior to refining and will produce the most flexible fibres. Spectral imaging showed sulphite treatment of impressarefiner chips to improve the optical properties of pulps with a clear dose-response shown at both higher and lower SEC levels, the former having the largest effect on whiteness. Photochemical effects of sulfonation using reflectance intensities showed complex results regarding lignocellulosic autofluorescence. Unlike wood, impressarefiner chips and pulp fibres showed a clear blue-shifted fluorescence maximum characteristic for a shortened conjugated system indicating that both the chipping and Impressafiner pretreatment induced a minor degradation of the lignocellulosic matrix that can be measured using spectral imaging. Refining however, increased the red edge fluorescence of the sulfonated whole long fibre fraction with a similar effect on the lignin fluorescence of wood. Using the HCL method of fibre analysis no significant trend for the effect of sulphite treatment was noted and only minor differences in fibre length were detected. Contents .

In this study, samples from 27-year-old Acacia aulacocarpa grown on a plantation were examined to determine suitable kraft pulping conditions and properties for paper production. The results showed that A. aulacocarpa had a high basic density of 0.65 g/cm 3 and a short fiber length of 0.84 mm. The derived values for Runkel, slenderness, and flexibility ratios were 1.02, 53.01, and 0.48, respectively. Five different active alkali concentrations ranging from 14% to 22%, with intervals of 2% were applied for kraft cooking. The percentages of reject, kappa number, and residual active alkali of black liquor were negatively related to the charge applied in pulping runs. Pulping with 18% active alkali content obtained a screened yield of 51.4% at a kappa number of 34.1. The 20% active alkali cook had the highest mechanical properties of the handsheets. The burst and tear indices met the Indonesian National Standard for leaf (hardwood) bleached kraft.

In the last 2-3 decades, environmental issues have been the dominant driving force for development of both pulping and bleaching processes. The bleach plant effluents have traditionally been the major contributors to polluting discharge. Proposed regulations of adsorbable organic halide (AOX) and the consumer's desire to buy environmentally friendly products have led pulp mills to implementAOX reduction strategies. The level of AOX can be decreased by extended delignification, oxygen delignification, substitution of Chlorine dioxide for chlorine, ECF Bleaching and TCF bleaching. The present paper highlights the effects of chlorine dioxide (CI02) substitution in sequence c/DEopDP2 applied to Kraft pulp of mixture of hardwoods and bamboo. Based on lab study, process scale trial up to 40% substitution was conducted. BOD~, COO, AOX and cblor were monitored for the effluent generated from bleach plant besides the regular parameters like brightness, reverted brightness and CEO viscosi...

Treatment of high-kappa sisal pulp with Trametes villosa laccase and ferulic acid resulted in strong increases of kappa-number and acid-group content due to biografting of this phenolic acid, as shown by pyrolysis in the presence of tetramethylammonium hydroxide. The coupling linkages were investigated by 2D NMR of the lignin isolated from pulps. The aromatic region of the spectra showed incorporation of the cinnamic molecule, representing ∼4% of the lignin content, that according to the displacement of its olefinic 13 C ␤ -1 H ␤ signal to 117.0/6.40 ppm would be C 4 -etherified. The aliphatic region of the spectra showed that ferulic acid also incorporates as the corresponding ␤-␤ dilactone (another ∼4% of the total lignin) with characteristic 13 C ␣ -1 H ␣ and 13 C ␤ -1 H ␤ correlations at 81.8/5.69 and 47.9/4.19 ppm, respectively. The sisal lignin in the treated pulps was only slightly modified (including a small increase of C ␣ -oxidized units) revealing that the main effect of the treatment was ferulic acid biografting.

RESUMO -Este trabalho objetivou classificar e selecionar clones de Eucalyptus sp, tendo em vista a qualidade das polpas kraft obtidas a partir de cada material. Os clones foram classificados quanto a rendimento depurado, viscosidade da polpa e álcali ativo usado no processo de polpação. A classificação dos clones foi realizada por meio da análise de agrupamento, utilizando-se o método de otimização de Tocher. A análise de agrupamento permitiu a separação dos clones em cinco grupos distintos, sendo encontrados grupos de clones com alto, médio e baixo potenciais para produção de polpa celulósica. As características que mais contribuíram para a divergência foram o rendimento depurado (58,1%) e a viscosidade da polpa celulósica (35,0%). Em geral, nos clones avaliados foram verificadas grandes variações com relação aos parâmetros estudados. Palavras-chave: Clone, Eucalyptus sp, polpa Kraft e análise de agrupamento.

In recent decades the pulp and paper industry has been reinventing to achieve an environmentally more friendly production process and to reduce costs. The decrease in water consumption as well as a lower production of organochlorine compounds has been the key to this conversion. In this work two novel sequences for bleaching Eucalyptus Kraft pulp that do not use chlorine dioxide in the first bleaching stage were studied and compared with a reference sequence normally used in the pulp and paper industry. This allow effluents generated in the acidic stage be reused to increase the mill closure and hence emissions to the environment could be diminished. The sequences A(EOP)DP and A(EOP)DD were optimized. The conditions of each stage were found and a 90% ISO brightness in the final pulp was achieved. Comparing these two novel sequences, the best results were obtained when hydrogen peroxide is used in the final stage. The final brightness, brightness reversion, ClO2 consumption, chlorate...

This paper deals with the study of the polysaccharide complex from Portuguese Pinus pinaster, as well as nom its main components, ie, holocellulose, cellulose and pulps obtained using different cooking'conditions. Nordic Pinus sylvestris was also studied in ...

In Portugal, pulp and paper industry uses especially two wood species, Eucalyptus globulus and Pinus pinaster. The second specie gives pulps with bad bleachability (compared with other common softwood species, like Pinus sylvester), that are used for packaging papers. ...

The effects of carbohydrate-degrading enzymes on three softwood kraft pulps, differing primarily in their initial fiber coarseness, were assessed. The pulps were treated with thrcc different enzyme preparations (a crude cellulase, an endoglucanase, and a xylanase) to assess the potential of the dif-Serent enzymes to alter handsheet properties and to evaluate their effects on fiber coarseness. All cnzymatic treatments increased handsheet densities irrespective of the furnish used. The most significant modifications in handsheet properties were evident after treatment with either the crude cellulase or the endoglucanase. Although increased densification occurred with all the pulps, the degree of fiber coarscness of the original pulp influenced thc magnitude of response to the different enzymatic treatments. While the tensile index of the coarser pulp was improved by treatment with the crude cellulase, a similar trcnd was not evident with the pulps of lower coarseness. In contrast, the tensile strength of all pulps, irrespective of the inherent fiber coarscness, was improved by the endoglucanase treatments. Thc tear strength decreased after treatments with both the crude cellulase and endoglucanase. Xylanase treatments did not significantly alter the handsheet properties of any of the pulps, regardless of the nature of the starting furnish.

For brownstock washing on rotary filters, the local, stage and overall efficiencies are defined. These form a hierarchy beginning with the most fundamental, the local efficiency, which is directly related to the rates of the underlying separation processes. Next is the stage efficiency which is most useful in characterizing the performance of a given filter stage. Finally, there is the overall efficiency which contains no detail about the process, but is simply a ratio of numbers of hypothetical to actual stages. The three efficiencies are related one to another without ambiguity. Single stage material balances are performed. These allow calculation of the stage efficiency in terms of the wash ratio, the recycle ratio and the local efficiency. A detailed analysis of mass transfer and fluid displacement in the wash zone is performed. This yields a simple, direct relationship between the local efficiency and the number of transfer units. This equation is modified to account for possible air entrainment in the pad which can render a portion of the shower water ineffective with respect to displacement. Performance equations are developed which give the wash loss directly in terms of wash ratio, stage efficiency and number of stages. Graphical depictions of calculation procedures are presented based on the concepts of operating and "Norden" lines. A minimum wash ratio is defined, and design equations yielding the required actual stages in terms of stage efficiency, wash loss and actual wash ratio are developed. The results compare very favorably with actual mill data.

Cationic polyacrylamide (CPAM) has been used as a retention aid with talc (hydrous magnesium silicate) filler to get the variation of ash in paper using response surface methodology based central composite design. The need of CPAM for varying dosage of talc filler is calculated statistically through the data of first pass ash retention (FPAR) using analysis of variance. The design is employed by selecting the dosages of talc filler and CPAM as model factors to get the variation of ash in paper. The dosages of talc and CPAM range from 250 g/t to 750 g/t and from 50 g/t to 400 g/t pulp respectively. The results of first order factorial design show that both independent variables have significant effect on increasing the ash in paper. At any particular filler addition level, the increase in CPAM addition enhances the ash and FPAR. Optimum conditions to get around 55% FPAR and 15% ash in paper are found to be 382 kg/t talc and 230 g/t CPAM. The linear equations obtained from the designe...

Biocatalytic pulp fibres were prepared using surface functionalization of bleached kraft pulp with amino groups (F) and further immobilization of a cross-linked glucose oxidase 20 (G*) from Aspergillus niger. The cross-linked enzymes (G*) were characterized using X-ray 21 spectroscopy, Fourier transform infrared spectroscopy, dynamic scanning calorimetry and 22 dynamic light scattering. According to standard assays, the G* content on the resulting fibers 23 (FG*) was of 11 mg/g of fiber, and enzyme activity was of 215 U/g. The results from confocal-24 and stimulated emission depletion microscopy techniques demonstrated that glucose oxidase do 25 not penetrate the interlayers of fibers. The benefit of pulp fiber functionalization was evident in 26 the present case, as the introduction of amino groups allowed the immobilization of larger 27 amount of enzymes and rendered more efficient systems. Using the approach described on this 28 paper, several advanced materials from wood pulp fibers and new bioprocesses might be 29 developed by selecting the correct enzyme for the target applications. 30

The mechanical pulping industry faces continued rising energy costs and increasing competition for raw material. In order to produce improved products based on mechanical pulp at lower energy consumption it is necessary to have a better understanding of the development of fundamental fibre properties during the processes. In particular, changes in fibre collapsibility, fibre fibrillation and fibre and surface development are of great interest. The overall goal of the CRUW Mechanical Pulping project is “Support development of more energy efficient mechanical pulping processes by increasing the knowledge on ultrastructural phenomena in mechanical pulping”. This project is working closely together with the Industrial Research College for Mechanical Pulping Technology bringing in the ultrastructural competence to more clearly understand and explain phenomena observed in these projects thus making it easier to develop new and improved processes to reduce energy consumption. This report p...

Background and Aim: Xylanases are widely used in various food industries, including livestock and poultry feed industries, the pulp and paper industry, as well as the pharmaceutical industry. Several strains of microorganisms are capable of producing this enzyme by different mechanisms, Bacilliaceae being one of its important sources at the commercial scale. The culture medium for xylan is expensive and, therefore, it is not economical to use in producing xylanase by Bacillus subtilis S7e. The purpose of this study was to explore the possibility of using industrial-agricultural wastes as a source of carbon and nitrogen in submerged fermentation, for producing xylanase in amounts higher than that which can be produced by xylan culture (10048 U/). Materials and methods: The indigenous strain of Bacillus subtilis S7e was cultured in the xylan medium, followed by incubation at 30°, 37° and 40° C. Then the nitrogen sources (rapeseed meal, soybean meal, tomato seeds, tea seeds, peptone, Vinas alcohol, casein, and ammonium sulfate) and carbon sources (molasses, wheat bran, rice bran, rice industry waste, gluten waste, malt waste, whey powder, and bagasse) were substituted for the meat and yeast extracts and the xylan culture medium, respectively. Results: The maximum enzyme activity was observed at 30° C after 48 hours of incubation (6183U/l). Rapeseed meal with an enzyme activity of 10048U/l and molasses with an enzyme activity of 3759U/l were found to be the best nitrogen and carbon sources for Bacillus subtilis S7e, respectively. Conclusion: Based on the findings of this study, from an economic point of view, agriculturalindustrial wastes (rapeseed meal and molasses) are an excellent substitute for the more expensive culture media currently in use for producing the enzyme xylanase.

The mechanical pulping industry faces continued rising energy costs and increasing competition for raw material. In order to produce improved products based on mechanical pulp at lower energy consumption it is necessary to have a better understanding of the development of fundamental fibre properties during the processes. In particular, changes in fibre collapsibility, fibre fibrillation and fibre and surface development are of great interest. The overall goal of the CRUW Mechanical Pulping project is “Support development of more energy efficient mechanical pulping processes by increasing the knowledge on ultrastructural phenomena in mechanical pulping”. This project is working closely together with the Industrial Research College for Mechanical Pulping Technology bringing in the ultrastructural competence to more clearly understand and explain phenomena observed in these projects thus making it easier to develop new and improved processes to reduce energy consumption. This report p...

Tension (TW) and opposite wood (OW) of Eucalyptus globulus trees were analyzed for its chemical characteristics and Kraft pulp production. Lignin content was 16% lower and contained 32% more syringyl units in TW than in OW. The increase in syringyl units favoured the formation of β-O-4 bonds that was also higher in TW than in OW (84% vs. 64%, respectively). The effect of these wood features was evaluated in the production of Kraft pulps from both types of wood. At kappa number 16, Kraft pulps obtained from TW demanded less active alkali in delignification and presented slightly higher or similar pulp yield than pulps made with OW. Fiber length, coarseness and intrinsic viscosity were also higher in tension than in opposite pulps. When pulps where refined to 30°SR, TW pulps needed 18% more revolutions in the PFI mill to achieve the same beating degree than OW pulps. Strength properties (tensile, tear and burst indexes) were slightly higher or similar in tension as compared with oppos...

Four xylanase preparations that are commercially available, namely Cartazyme from Sandoz, Ecopulp from Alko-ICI, Irgazyme from Ciba-Genencor and Pulpzyme HB from Novo Nordisk, were tested in bleaching experiments of kraft pulps from pinus rudiata. The main objective of this study was to optimize a reduction in the consumption of chlorine dioxide in the bleaching sequences C

A wide range of kraft pulps from radiata pine produced by low-temperature kraft pulping in flow-through reactors was assessed for carboxyl and hexenuronic acid (HexA) contents using the conductometric titrations and UV spectrophotometer, respectively. The Kappa number of pulps varied from 20.8 to 84.7 when using a cooking liquor of 1 M effective alkali as Na 2 O, 25% sulfidity, and cooking time of 100-250 min. The experimental results showed that the carboxyl groups (including HexA) and HexA groups dissolved and their residual values in the pulp samples correlate linearly with Kappa number and pulp yield. The dissolving rate of all carboxyl groups is much faster than the loss of HexA. The HexA/lignin ratio decreased non-linearly with Kappa number.

A eficiência da deslignificação com oxigênio (pré-O 2) é muito baixa para polpas de baixo número kappa e que contêm altas concentrações de ácidos hexenurônicos, pois o oxigênio não reage com esses ácidos, sendo mínima a eliminação destes durante a deslignificação com oxigênio em simples ou duplo estágio. Neste estudo, investigaram-se as propriedades físico-mecânicas de polpas produzidas por cozimentos cineticamente modificados até número kappa 17 e 14 e branqueadas pelas técnicas AD(EO)D, para polpa de kappa 17 e D HT (EPO)DP, para polpa de kappa 14. O objetivo principal do estudo foi o de avaliar as propriedades físicomecânicas das polpas submetidas a sequências de branqueamento sem o oxigênio, no início da sequência. Como referências, foram produzidas polpas de número kappa 17 e 14 as quais foram posteriormente deslignificadas com oxigênio e branqueadas com sequências convencionais: A/D(EO)D, para polpa de número kappa 17 e D HT (EPO)DP, para polpa de kappa 14. O branqueamento alternativo, sem a pré-O 2 , resultou em polpas branqueadas de maior integridade que as da referência, o que foi comprovado pelos valores significativamente mais altos de VEA (bulk), índice de rasgo, opacidade e resistência à passagem de ar (RPA) da polpa fracamente refinada (polpa para produzir papel tissue). Por outro lado, a alta integridade das fibras oriundas das polpas branqueadas por processos alternativos diminuiu suas conformabilidades e colapsabilidades, com consequente diminuição do índice de tração da polpa fracamente refinada. Porém, mediante um refino mais intenso (polpa para produzir papel de imprimir e escrever-P&W) o índice de tração foi recuperado. A alta integridade das polpas branqueadas sem a pré-O 2 dificulta o seu refino. Para alcançar o grau de drenagem de 35 o SR com as polpas provenientes dos processos alternativos de branqueamento, foi necessário aplicar cerca de 30% a mais de energia em relação à referência.

A eficiência da deslignificação com oxigênio (pré-O 2) é muito baixa para polpas de baixo número kappa e que contêm altas concentrações de ácidos hexenurônicos, pois o oxigênio não reage com esses ácidos, sendo mínima a eliminação destes durante a deslignificação com oxigênio em simples ou duplo estágio. Neste estudo, investigaram-se as propriedades físico-mecânicas de polpas produzidas por cozimentos cineticamente modificados até número kappa 17 e 14 e branqueadas pelas técnicas AD(EO)D, para polpa de kappa 17 e D HT (EPO)DP, para polpa de kappa 14. O objetivo principal do estudo foi o de avaliar as propriedades físicomecânicas das polpas submetidas a sequências de branqueamento sem o oxigênio, no início da sequência. Como referências, foram produzidas polpas de número kappa 17 e 14 as quais foram posteriormente deslignificadas com oxigênio e branqueadas com sequências convencionais: A/D(EO)D, para polpa de número kappa 17 e D HT (EPO)DP, para polpa de kappa 14. O branqueamento alternativo, sem a pré-O 2 , resultou em polpas branqueadas de maior integridade que as da referência, o que foi comprovado pelos valores significativamente mais altos de VEA (bulk), índice de rasgo, opacidade e resistência à passagem de ar (RPA) da polpa fracamente refinada (polpa para produzir papel tissue). Por outro lado, a alta integridade das fibras oriundas das polpas branqueadas por processos alternativos diminuiu suas conformabilidades e colapsabilidades, com consequente diminuição do índice de tração da polpa fracamente refinada. Porém, mediante um refino mais intenso (polpa para produzir papel de imprimir e escrever-P&W) o índice de tração foi recuperado. A alta integridade das polpas branqueadas sem a pré-O 2 dificulta o seu refino. Para alcançar o grau de drenagem de 35 o SR com as polpas provenientes dos processos alternativos de branqueamento, foi necessário aplicar cerca de 30% a mais de energia em relação à referência.

Eucalypts are among the most important short-rotation hardwoods, planted worldwide for the pulp and paper industry. Even though the genus comprises over 700 species, only about a dozen species are used for pulping purposes, therefore, showing the potential for diversification. Six-year-old eucalypt trees from 12 species (Eucalyptus botryoides, Eucalyptus camaldulensis, Eucalyptus globulus, Eucalyptus grandis, Corymbia maculata, Eucalyptus ovata, Eucalyptus propinqua, Eucalyptus resinifera, Eucalyptus rudis, Eucalyptus saligna, Eucalyptus sideroxylon, and Eucalyptus viminalis) were analyzed for chemical composition, fiber morphological, pulping and handsheet paper properties to determine their kraft pulping suitability. The 12 species showed substantial differences regarding extractives (6.1-18.9%), lignin (21.6-30.8%) and holocellulose content (55.4-70.1%). The high inter-species variation in chemical composition produced pulps with different yields (between 38.9 and 49.8%) and degree of delignification (kappa number between 11.6 and 24.2). The combination of these results with the morphological and handsheet properties suggests that E. globulus, E. ovata, E. grandis, E. saligna and E. botryoides have the best overall characteristics for kraft pulping.

A wide range of kraft pulps from radiata pine produced by low-temperature kraft pulping in flow-through reactors was assessed for carboxyl and hexenuronic acid (HexA) contents using the conductometric titrations and UV spectrophotometer, respectively. The Kappa number of pulps varied from 20.8 to 84.7 when using a cooking liquor of 1 M effective alkali as Na 2 O, 25% sulfidity, and cooking time of 100-250 min. The experimental results showed that the carboxyl groups (including HexA) and HexA groups dissolved and their residual values in the pulp samples correlate linearly with Kappa number and pulp yield. The dissolving rate of all carboxyl groups is much faster than the loss of HexA. The HexA/lignin ratio decreased non-linearly with Kappa number.

Grafting natural antibacterial phenols onto lignocellulosic materials is an environmentally friendly way of imparting antibacterial properties to the substrates. In the present investigation, wood veneer and pulp were treated with tannins in the presence or absence of laccase. Treatments with hydrolysable tannins significantly improved the antibacterial resistance of veneers and paper made from tannin-treated pulp against a Gram-positive bacterium (Staphylococcus aureus) while a more modest protective effect was observed against a Gram-negative bacterium (Escherichia coli). Condensed tannin improved the antibacterial resistance against S. aureus, albeit less than hydrolysable tannin, but had little effect on E. coli. A cationic condensed tannin derivative bearing a quaternary amino group provided far better resistance to pulp against S. aureus and E. coli than the corresponding unmodified condensed tannin. These findings agree with the minimal inhibitory concentrations (MICs) of the tannins and their reactivities toward laccase as determined by O 2 consumption measurements. Due to a better retention of tannins via covalent bonding, treatments with laccase usually resulted in greater antibacterial effects than those without laccase. LC-MS investigations with monomeric tannin and lignin model compounds showed that covalent bonding of tannin to lignin via radical coupling occurred in the presence of laccase.

A single Norway spruce tree (Picea abies) was manually fractionated into heartwood, sapwood, juvenile wood and branches. These fractions were chemically pulped, individually, in laboratory scale. The pulps were characterized and investigated in relation to dewatering behavior and sheet strength properties. An unbleached and unbeaten commercial kraft pulp from softwood fibers was used as a reference, and the fractionated pulps were within the same range in all tested properties. The fractionated pulps were then compared with each other, and fiber characteristics were used to explain differences in dewatering and strength. Heartwood pulp results in stronger and stiffer papers that are harder to dewater. Sapwood pulp gives more open network structures resulting in easy dewatering and high air permeance, although with lower strength properties compared to heartwood. Pulp from Juvenile wood gives s quite strong but brittle sheets, with efficient dewatering. Pulp from branches gives paper sheets with efficient dewatering, air permeance and relatively high elongation of break but lower strength. The results show that there is definitely potential for utilizing more parts of the trees for pulp and paper making, especially when tailoring the raw material origins after preferred paper properties.

Kraft pulps prepared from beech chips, with 10% wood weight loss, pre-extracted with green liquor solution, hot water and dilute oxalic acid, were more effectively delignified by a double-stage oxygen system in comparison with the reference pulp from original chips. The highest delignification efficiency was demonstrated for pulps prepared from dilute oxalic acid and hot water pre-extracted chips. The bleachability of oxygen delignified kraft pulps in the sequence D0(EO)D1D2 was better in the case of the pulps from pre-extracted chips, first for those extracted with dilute oxalic acid and then for the hot water extracted ones. The consumption of ClO2 in bleaching was lower for these pulps by about 40% and 20%, respectively, while for the pulp from green liquor solution pre-extracted chips it was lower only by about 5% compared with the reference pulp. Brightness reversion of the bleached pulps from pre-extracted chips was lower in comparison with the reference pulp, which correlates...

Many studies have shown that kraft-pulping yield can be improved by xylan re-adsorption into the pulp during cooking. Kraft black liquor contains a significant fraction of wood xylans, being an important source of these macromolecules. This study evaluated the effect of different additions of black liquor (25, 50, 75 and 100% v/v) on conventional kraft pulping. Cooking was conducted up to kappa number 17-18 and the resulting pulps were de-lignified with oxygen under fixed conditions. Kraft cooking with the addition of 50% v/v of black liquor resulted in an increase of 1.5% in the yield; of 0.5% in pentosan content and of 4.7 mmol/kg in HexAs content, compared to that of the reference cooking, with an increase in the black liquor contents of total solids (3.4%) and organic solids (1.7%). The resulting kraft pulp had a good performance in the predelignification with oxygen, except for a 1.2% ISO lower whiteness.

A grande dependência por madeiras das espécies dos gêneros Eucalyptus e Pinus associada à busca por produtos de diferentes qualidades impulsionam estudos acerca de madeiras alternativas para fins industriais, principalmente de espécies do bioma Caatinga, pouco estudado para fins florestais. O objetivo deste estudo foi caracterizar quimicamente a madeira da espécie Pterogyne nitens assim como analisar seu potencial para produção de polpa celulósica. Foram colhidas três árvores representativas de 9 anos, em um plantio experimental localizado na Universidade Estadual do Sudoeste da Bahia – Campus Vitória da Conquista, e amostradas cinco seções do fuste entre as posições 0, 25, 50, 75 e 100% da altura comercial. Os toretes foram transformados em cavacos e homogeneizados formando uma amostra composta representativa para a análise de densidade básica e composição química completa, bem como para a realização da polpação Kraft (cinco cozimentos utilizando diferentes cargas de álcali efetivo...

The improvement caused by eucalypt chip impregnation on kraft pulping performance was assessed for terminating the cook at kappa in the range of 15–27 and at controlled residual effective alkali (REA) of 6–8 g/L NaOH. Extended impregnation cooking of eucalypt chips (EIC) increased about 1 %lignin- and HexA-freescreen yield gains in relation to conventional cooking (CC), regardless of kappa number in the range of 15–27. The EIC technology allows for cooking eucalypt wood to kappa number up to 27, without rejects production, but without significant improvement inlignin- and HexA-freescreen yield and with larger chlorine dioxide (ClO2) consume during bleaching. The optimum kappa number for both CC and EIC cooking was about 19 with similar refinability and strength properties for both technologies, CC and EIC. It was concluded that extended impregnation cooking is an attractive technique for enhancing bleached eucalypt Kraft pulp yield.

It is well known that pH is an important parameter for controlling the eucalyptus pulp bleaching when using the final chlorine dioxide stage, since it affects the effectiveness of the process. Recommendations found in the literature for operating are in the 3.5 to 4.0 range. However, in this paper it was shown that final chlorine dioxide has better performance, with significant brightness gain while also preserving pulp quality, when it is operated at near neutral pH. This result can be explained by the generation of sodium bicarbonate in situ upon adding carbon dioxide at this stage.

A wide range of kraft pulps from radiata pine produced by low-temperature kraft pulping in flow-through reactors was assessed for carboxyl and hexenuronic acid (HexA) contents using the conductometric titrations and UV spectrophotometer, respectively. The Kappa number of pulps varied from 20.8 to 84.7 when using a cooking liquor of 1 M effective alkali as Na 2 O, 25% sulfidity, and cooking time of 100-250 min. The experimental results showed that the carboxyl groups (including HexA) and HexA groups dissolved and their residual values in the pulp samples correlate linearly with Kappa number and pulp yield. The dissolving rate of all carboxyl groups is much faster than the loss of HexA. The HexA/lignin ratio decreased non-linearly with Kappa number.

Bleached eucalyptus kraft pulps are largely used for manufacturing tissue and print & writing (P&W) paper grades. High final brightness (92 + % ISO) and brightness stability (<2% ISO) are rather significant for P&W for it affects optical brighteners demand. Bleaching chemical demand, bleaching yield, water consumption, effluent load & treatability, pulp OX, brightness stability, refinability and strength are drivers for choosing bleaching technology. This work critically reviews the state-of-the-art processes for oxygen delignification, first stage, second stage and final bleaching of eucalyptus kraft pulp in the light of the aforementioned drivers. The potential of new bleaching technologies such as the P Mo stage and the use of formaldehyde in D-stages are also presented. Implementation of single or double-stage oxygen delignification is determined by the true pulp lignin content (discounted the HexA´s). The high pulp HexA´s content and poor oxygen stage selectivity limits dropping kappa number under 9-10 in single or double Ostage. Application of Mo-catalyzed acid peroxide delignification after O-stage allows further reduction of kappa number to 3-4. Efficient post-oxygen washing is the key for low cost bleaching, with a kg of COD/odt consuming the equivalent to 0.085% active chlorine. A D-(EP)-D type three stage sequences suffices for bleaching eucalyptus kraft pulps. The inclusion of a fourth stage is desirable for production of high brightness/ low reversion pulps. Bleaching chemical consumption is strongly influenced by brown pulp origin, with variations of 3.2 to 7.7% active Cl 2 demand depending upon the pulp type. The type of ECF Bleaching technology, based on chlorine dioxide, affects chemical consumption only slightly. Hot acid/hot chlorine dioxide bleaching technology saves small amounts of active chlorine for high bleachability pulps but none for low bleachability ones. Atmospheric extraction (EP) suffices for eucalyptus kraft pulp bleaching. Formaldehyde saves more chlorine dioxide when used in D 1 than in D 0 /D HT stages. A final peroxide stage significantly improves pulp brightness stability. The production or organically bound chlorine decreases by 30% with hot chlorine dioxide bleaching but this gain disappears after effluent biological treatment.

Renewable waste-based fuels may decrease the resource use and environmental impact of the road transport sector; one of the options is biogas produced via anaerobic digestion of waste streams from pulp and paper mills. This paper describes process simulation and economic assessments for two options for integrating anaerobic digestion and production of liquid biogas in a typical Nordic Kraft pulp mill: (1) a high-rate anaerobic reactor in the wastewater treatment, and (2) an external anaerobic stirred tank reactor for the treatment of primary and secondary sludge as well as Kraft evaporator methanol condensate. The results revealed an annual production potential of 26-27 GWh biogas in an average Nordic Kraft pulp mill, which is equivalent to a daily production of 7600 litres of diesel in terms of energy, and the production cost was estimated to €0.47-0.82 per litre diesel equivalent, comparable with the Swedish price of €0.68 per litre diesel. However, for the cases with LBG, a discounted payback period of about 8 years may not be considered profitable by the industry. Other prerequisites may, however, improve the profitability: a larger mill; production of compressed biogas instead of liquid biogas; or, for case 1, a comparison with the alternative cost for expanding the wastewater treatment capacity with more process equipment for activated sludge treatment. The results reveal that anaerobic digestion at pulp mills may both expand the production of renewable vehicle fuel but also enable increased efficiency and revenue at Kraft pulp mills.

The mechanical pulping industry faces continued rising energy costs and increasing competition for raw material. In order to produce improved products based on mechanical pulp at lower energy consumption it is necessary to have a better understanding of the development of fundamental fibre properties during the processes. In particular, changes in fibre collapsibility, fibre fibrillation and fibre and surface development are of great interest. The overall goal of the CRUW Mechanical Pulping project is “Support development of more energy efficient mechanical pulping processes by increasing the knowledge on ultrastructural phenomena in mechanical pulping”. This project is working closely together with the Industrial Research College for Mechanical Pulping Technology bringing in the ultrastructural competence to more clearly understand and explain phenomena observed in these projects thus making it easier to develop new and improved processes to reduce energy consumption. This report p...

The mechanical pulping industry faces continued rising energy costs and increasing competition for raw material. In order to produce improved products based on mechanical pulp at lower energy consumption it is necessary to have a better understanding of the development of fundamental fibre properties during the processes. In particular, changes in fibre collapsibility, fibre fibrillation and fibre and surface development are of great interest. The overall goal of the CRUW Mechanical Pulping project is “Support development of more energy efficient mechanical pulping processes by increasing the knowledge on ultrastructural phenomena in mechanical pulping”. This project is working closely together with the Industrial Research College for Mechanical Pulping Technology bringing in the ultrastructural competence to more clearly understand and explain phenomena observed in these projects thus making it easier to develop new and improved processes to reduce energy consumption. This report p...

In present study, single and consecutive applications of xylanase and lignin peroxidase were performed in an XOQP TCF sequence to bleach pine and eucalypts kraft pulp. The consecutive use of Geobacillus sp. strain 71 xylanase and Rhodococcus jostii RHA1 lignin peroxidase was more effective than the single uses. XyzGeo71 treatment (X) indicates a 9,76% and 28,52% reduction in kappa number for pine and eucalypts kraft pulps, respectively. LiPRHA1 treatment (X) showed a 7,88% and 20,9% reduction a in kappa number for pine and eucalypts kraft pulps, respectively. The consecutive treatment of XyzGeo71 and LiPRHA1 (X), however, indicated a 13,67% and 37,2% reduction in kappa number for pine and eucalypts kraft pulps, respectively. The results showed that delignification with the consecutive xylanase and lignin peroxidase treatment was very significant.

This paper summarizes the review of developments in the area of ozone-based elemental chlorine free (ECF) and total chlorine free (TCF) bleaching of wood and non-wood pulps. Focused areas of review are reaction mechanism of ozone with carbohydrates and lignin, effect of process conditions maintained during ozone bleaching on pulp properties, effect of using different cellulose protectors, effect of alkaline extraction after ozone bleaching of pulps, effect of ozone bleaching on final bleached pulp properties, ECF and TCF bleaching sequences used along with ozone for of wood and non-wood pulps, and commercial scale utilization of ozone for pulp bleaching.

Biocide programs have become necessary in most fine paper manufacturing circuits, as drastic reduction of fresh water consumption in the industry enhances microbial development. Depending on their chemical nature, biocides may interfere with typical wet-end chemistry additives and furnish. A reference wet-end chemistry was set (including fixing aid, dry strength aid, sizing agent, and retention system), then biocides were added to the furnish (bleached virgin fibres + mineral filler) prior to handsheet making. Four of the tested biocides (organo-sulfur, dibromonitrilopropionamide, isothiazoline, and glutaraldehyde) were not found to interact with wet-end chemistry. On the other hand, the tested quaternary ammonium salt biocide showed very detrimental effects: it reduced filler retention in the sheet, decreased sheet strength, and destroyed sizing (sheet hydrophobicity).

The study was conducted to analyze a chemical composition of unbleached softwood kraft pulp fibers depending on kappa number. It was shown that a rise of kappa number within interval 18-50 units decreases hard-hydrolysable carbohydrates content by 12.5 %, increases easy-hydrolysable carbohydrates content by 1.0 % and increases residual lignin content by 1.8 %. It was also observed that extractives content makes a curve with minimum of 0.8 % at kappa number 28-38.

The function of water in the adhesion between wet cellulose fibers both in the assembly of papers and the establishment of the properties is discussed. The contributions of friction and hydrogen bonds are reviewed, together with the new concept of interfiber ordered water structure created by the hydrophilic surfaces of the fibers. Procedures for the enhancement of interfiber adhesion are summarized in terms of the accessibility, the stereotopochemistry and the enthalpies of the interacting moieties on contiguous surfaces.

In this work, the laboratory-made handsheets having different grammages were obtained at certain production conditions. The tensile characteristics of the laboratory-made handsheets were analysed by using two measuring techniques. The main method for determining tensile behaviour was performed on the universal testing machine, which is a generally accepted conventional testing machine. A rheometer device was used as a second and alternative method for measuring the tensile properties of handsheets. The given data were investigated and compared with the data of conventional tensile tester. Linear least square regression was applied to analyse the association of the data from the Instron 5564 Universal Testing Machine and Hybrid Rheometer Discovery HR-2 Machine with examined tensile characteristics depending on the various grammage range. The experiments on the handsheets having different grammage groups showed that the methods give results in reasonable agreement. These results showed that there are acceptable differences in the tensile index and elastic modulus values of the samples as a function of their basis grammages.