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The use of 12-year-old Pinus tecunumanii (Eguiluz e Perry) grown in Colombia was evaluated for bleached kraft pulp production. Kraft pulps of kappa number 30 ± 1 were produced, and oxygen delignified and bleached to 90% ISO with ECF processes. The bleached pulps produced under optimum conditions were evaluated with regard to their strength properties. Pinus tecunumanii wood required low effective alkali charge to reach the desired kappa number and the unbleached pulp showed high oxygen delignification efficiency and bleachability when a OD(EO)DED sequence was used. The bleached pulps presented good physical-mechanical properties, which are comparable to those obtained with more traditional pines such as Pinus taeda and Pinus radiata. The results demonstrate that this tropical pine species is a suitable raw material for bleached kraft pulp productionForam avaliadas amostras de Pinus tecunumanii de (Eguiluz e Perry) com 12 anos de idade procedente da Colômbia, para produção de polpa de kraft branqueada. Produziram-se polpas kraft com número kappa 30±1, deslignificada com oxigênio e branqueada a 90% ISO por processo ECF. As polpas branqueadas foram produzidas em condições ótimas e avaliadas com relação às suas propriedades de resistência. A madeira de Pinus tecunumanii exigiu baixa carga de álcali efetivo para alcançar o número kappa desejado, e a polpa marrom mostrou eficiência na deslignificação com oxigênio e alta branqueabilidade quando submetida à seqüência OD(EO)DED. As polpas branqueadas apresentaram boas propriedades físico-mecânicas, em comparação com aquelas obtidas das espécies tradicionais de Pinus, como o Pinus taeda e o Pinus radiata. Os resultados indicaram que essa espécie de pinus tropical é uma matéria-prima satisfatória para produção de polpa de kraft branqueada.

Foram analisados clones de Eucalyptus de última geração, pertencentes às principais empresas brasileiras de celulose. Os estudos consistiram numa caracterização tecnológica detalhada da qualidade das madeiras utilizadas no processamento fabril das empresas. Foram realizadas análise químicas detalhadas das madeiras e cozimentos kraft, simulando-se uma das modernas técnica de digestor contínuo. Os resultados indicaram a alta qualidade dos clones de Eucalyptus atualmente plantados no Brasil para produção de celulose.Last generation of Eucalyptus clones pulped by the main Brazilian kraft pulp mills were used for this study. Detailed chemical analysis of the woods were carried out to establish the wood quality. Laboratory simulation of a modern continuous digester technique was used for pulp production. Results demonstrated the high quality of Eucalyptus clones wood that are being planted in Brazil for kraft pulp production.

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.The objectives of this study were to classify and select clones of Eucalyptus sp, aiming at pulp quality improvement. The clones were classified according to the screened yield, pulp viscosity and active alkali used for pulping. Classification of the clones was achieved by cluster analysis using the Tocher method. The clones were classified in groups having high, medium and low potential for pulp production. The results showed that the parameter that most contributed to group the different Eucalyptus sp clones was the screened yield (58,1%), followed by pulp viscosity (35,0%). In general, large variation was observed for the parameters evaluated.

Various process parameters affecting eucalyptus kraft pulp delignification with peroxyacetic acid were investigated. The results showed that pH was an important factor. The delignification rate increased with increasing pH to the value of 6. High delignification rate was obtained when the pulp was chelated with Na4-EDTA prior to the peroxyacetic acid stage. Therefore, delignification reaction rate depends on peroxyacid charge, temperature, pH and metal content of pulp.

Estudou-se uma nova técnica laboratorial de análise de qualidade da madeira de Eucalyptus sp. para produção de polpa celulósica kraft. A técnica consiste em realizar, simultaneamente, quatro cozimentos de cavacos utilizando diferentes cargas de álcali ativo para estabelecer a característica de deslignificação da madeira. Pelo uso de equações de regressão, calcula-se o álcali ativo necessário para obter o número kappa desejado, o rendimento, a viscosidade e álcali consumido para o kappa objetivo. Os estudos estatísticos evidenciaram que uma única batelada de quatro cozimentos é suficiente, não sendo necessário realizar repetições.A new laboratory technique was tested to determine Eucalyptus sp. wood quality for kraft pulp production. This technique consists in performing four cooks simultaneously using different active alkali charges to establish the wood delignification characteristics. Based on regression equation it is possible to determine the alkali charge necessary to obtain a desired kappa number and the yield, viscosity and the alkali consumed for the target kappa. Statistical analysis demonstrated that a set of four cooks without replication is sufficient to determine the wood quality characteristics.

Microfibrillated cellulose (MFC) is an emerging cellulosic material that has shown enormous potential in various industrial sectors such as food packaging, cosmetics, pharmaceuticals, filler for cement and paper, and others. Yet, there is still the need to improve its processing in order to reach its full potential. Despite research efforts for the production of MFC, the production volumes remain low because the costs of these products are hardly competitive with synthetic polymers. The present study investigates the conversion of bleached Kraft pulp into MFC using three different oxidative treatments: (1) oxidation with sodium periodate followed by oxidation with hydrogen peroxide to enrich the pulp with carboxyl groups; (2) activation of hydrogen peroxide with copper to produce hydroxyl radicals; and (3) use of hydrogen peroxide alone in alkaline medium. Treatments (1) and (2) allowed producing interesting MFC with reduced energy consumption. [Display omitted] [ABSTRACT FROM AUTHOR]

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 L 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 liquid biogas (LBG), a discounted payback period of about 8 years may not be considered profitable by the industry. Other pre-requisites 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. [ABSTRACT FROM AUTHOR]

This study focused on the process development for the d -lactic acid production from cellulosic feedstocks using the Lactobacillus plantarum mutant, genetically modified to produce optically pure d -lactic acid from both glucose and xylose. The simultaneous saccharification and fermentation (SSF) using delignified hardwood pulp (5–15% loads) resulted in the lactic acid titers of 55.2–84.6 g/L after 72 h and increased productivities of 1.77–2.61 g/L/h. To facilitate the enzymatic saccharification of high-load pulp at a fermentation temperature, short-term (⩽10 min) pulverization of pulp was conducted, leading to a significantly improved saccharification with the suppressed formation of formic acid by-product. The short-term milling followed by SSF resulted in a lactic acid titer of 102.3 g/L, an optical purity of 99.2%, and a yield of 0.879 g/g-sugars without fed-batch process control. Therefore, the process presented here shows promise for the production of high-titer d -lactic acid using the L. plantarum mutant. [ABSTRACT FROM AUTHOR]

The article discusses a study which aims to improve kraft pulp saccharification efficiency through a cellulose cocktail derived from genetically engineered Aspergillus oryzae. Topics discussed include the quantification of the protein concentration of cellulase secretion, determining the modified ratio of cellulase cocktail, and the application of a simultaneous saccharification and fermentation (SSF) process to assess modified cellulose cocktail application.

A TCF bleaching sequence consisting of a urea pretreatment stage (U), laccase-mediator system stage (L), alkaline extraction stage (E), and hydrogen peroxide bleaching stage (P) was used to study the effect of five independent variables on the dependent variables pulp properties, hydrogen peroxide consumption, and residual enzyme activity. Results showed that the most influential variable was L stage pulp consistency, followed by mediator and laccase dosages. On the other hand, oxygen pressure did not have a significant effect. The optimal UL partial sequence significantly enhanced the EP bleaching sequence: 49.8% vs. 33.4% delignification, up to 65.6% ISO vs. 56.3% ISO bleached brightness, and 50.3% vs. 89.9% peroxide consumption in the P stage. The ULE partial sequence also improved an ECF bleaching sequence (ULED0E1D1): 0.6 vs. 1.0 final kappa number; 82.7% ISO vs. 76.0% ISO brightness; and 54.1 N·m·g-1 vs. 51.9 N·m·g-1 and 3.3 KPa·m²·g-1 vs. 2.7 KPa·m²·g-1, tensile and burst indexes, respectively, when compared to the control D0E1D1 sequence. [ABSTRACT FROM AUTHOR]

Chemical modifications of cellulose fibres (kraft pulp) in NaOH/H2O and NaCl/H2O systems were investigated. Handsheets were prepared that contained 25% of the modified fibres. Changes in the modified samples were examined by measuring their mechanical and optical properties and comparing them to those made with unmodified fibres. The observed differences were explained and supported by structural analyses, by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that the NaOH/H2O pretreatment led to a significant deterioration of optical and strength properties of the handsheets. These modifications affected both the inner part of the crystalline cellulose (change from cellulose I to cellulose II) and the morphology of the fibers. Conversely, these properties slightly improved after propargylation, due to the propargyl functional groups. For the NaCl/H2O system, a significant enhancement of the mechanical properties of the handsheets was noted, such as an increase of up to 108% of the tear index. The propargylation further increased the tear index (by 157%). These enhancements were not accompanied by significant changes at both the micrometric and nanometric scales, except for the increase of the crystallinity index after propargylation. [ABSTRACT FROM AUTHOR]

This paper describes a cradle-to-gate life cycle assessment of offset paper production in Brazil. The production system is classified into two subsystems: a forest production subsystem, which involves seedling production, soil preparation, seedling planting, forest maintenance, and wood harvesting and transport processes; and an industrial production subsystem, involving wood pulp extraction and bleaching, chemical recovery, and offset paper manufacturing processes. The environmental analysis includes the primary energy demand, environmental impact assessment, and land use indicators. The primary energy demand indicated that the largest amount of both renewable and non-renewable primary energy is consumed by the industrial production subsystem, accounting for 91.0% of the total energy demand. The potential environmental impact assessment included eight impact categories: acidification, ecotoxicity, global warming, human toxicity – cancer effects, human toxicity – non-cancer effects, nutrient enrichment, ozone depletion, and photochemical oxidation. Most of the potential impacts are attributed to the processes of pulp extraction and bleaching, and offset paper manufacturing, mainly due to the production of electricity and thermal energy. As for impacts on land use during the forest activities, a recent developed approach was applied for the regionalized assessment of impacts. Land occupation impacts on erosion resistance, physicochemical filtration, and mechanical filtration showed a reduction in the soil ecological functions, whereas groundwater recharge indicated a credit for the performance of the soil function. With a view to reducing the main life cycle impacts of the industrial production subsystem, an evaluation is made of alternative production scenarios. The best scenario was the substitution of biomass and diesel in the energy generation unit by biomass gasification and optimization of the recovery boiler. [ABSTRACT FROM AUTHOR]

In this study, the chemical composition, fiber morphology, pulp, and paper properties of the pomegranate tree (Punica granatum L.) were determined. Stem and branch wood were analyzed separately. Kraft and kraft- anthraquinone (AQ) methods were used for the pulping processes. Stem wood showed superiority to branch wood with longer, wider, thicker-walled fibers. The holocellulose, α-cellulose, and lignin contents of branch and stem wood were 72.98%-73.50%, 38.37%-39.92%, and 21.04%-25.29%, respectively. In addition, the yield of kraft pulp made from stem wood was higher than that of branch wood. However, branch wood handsheets had higher strength properties and brightness than those of stem wood handsheets. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Two chemical processes for hemicellulose extraction have been applied on a softwood kraft pulp in an attempt to convert paper pulp into dissolving grade pulp. The cold caustic extraction process (CCE) was performed under conventional and unconventional conditions. Alkali concentration ranged from 3% to 12% and temperature from 25 to 110 °C. As expected, the results showed that NaOH concentration had a predominant effect on xylan and glucomannan removal. The effect of temperature was more complex since the best removal was observed below 40 °C or above 80 °C. The unexpected good results obtained at high temperature would be due to the contribution of some alkaline degradation. Under the best conditions, 80% of the xylan and 60% of the glucomannan were removed. The cellulose II content was measured by solid state NMR spectroscopy. Formation of cellulose II increased with the concentration of caustic soda and was correlated to the extraction of hemicellulose. A second process consisting in an acid stage at high temperature (up to 150 °C) followed by a hot caustic extraction (A-HCE) was also tested. Promising results in terms of hemicellulose removal were obtained when temperature in A was above 140 °C. This might be due to a combination of acidolysis during A and peeling reactions during HCE. However, cellulose was partly depolymerized because of the severity of the A step. The two processes were compared in the context of getting to a viscose grade dissolving pulp. [ABSTRACT FROM AUTHOR]

The importance of enzymes as biotechnological catalysts for paper industry is now recognized. In this study, five cellulase formulations were used for fibre modification. The number of PFI revolutions decreased by about 50% while achieving the same freeness value (decrease in CSF by 200 mL) with the enzymatic pretreatment. The physical properties of handsheets were modified after enzymatic pretreatment followed by PFI refining. A slight decrease in tear strength was observed with enzymes C1 and C4 at pH 7 while the most decrease in tear was observed after C2, C3, C5 treatments. C1 and C4 which had xylanase activity improved paper properties, while other enzymes had a negative impact. Therefore, the intricate balance between cellulolytic and hemicellulolytic activity is the key to optimizing biorefining and paper properties. It was also observed that C1 impact was pH dependent, which supports the importance of pH in developing an enzymatic strategy for refining energy reduction. [ABSTRACT FROM AUTHOR]

Pinus radiata D. Don wood chips were submitted to a hydrothermal (HT) process, which is a pretreatment with pressurized water at P-factors of 20 (E1) and 1200 (E2), leading to 27% and 56% of hemicellulose removal, respectively. The residual wood chips were pulped by the chemithermomechanical (CTMP) and kraft processes. The pulp yield in the HT/CTMP process was in the range of 56-75%. The cellulose yields were not affected by the HT pretreatment, whereas the solubilization of hemicelluloses and lignin was intensified. The HT process provided energy savings in the refining of CTMP pulps, and the E1/CTMP pulp had a similar tensile and increased tear strength as the control wood. For kraft pulping, the HT wood chips demanded more active alkali (AA) to achieve a κ number (KN) of 30, and consequently, a decrease in pulp yield was observed (47.2% yield in the control and 44.4% and 37.8% in the E1 and E2 pulps, respectively). The fiber length decreased in the E1 and E2 kraft pulps compared with their control samples. In the E1 pulps, the tensile, tear, and burst indexes decreased by 10%, 25%, and 30%, respectively. Considering the low hemicellulose content and pulp viscosity in the range of 800-900 ml g-1, the mild HT process of P. radiata would be better suited for preparing cellulose-rich materials instead of paper-grade pulps under the biorefinery concept. [ABSTRACT FROM AUTHOR]

Paper pulp bleaching plants using elemental chlorine produced large quantities of dioxins. Dioxins are the organic pollutants that are mostly toxic human-released pollutants in the atmosphere. Dioxins are highly toxic pollutants, which cause a lot of health effects on human's reproductive, developmental, immune and hormonal problems. Dioxins easily reach the human beings through food, as dioxins accumulate in the food chain in the fatty tissue of animals. Elemental chlorine bleaching has been largely replaced by chlorine dioxide and the formation of dioxin is reduced. ECF (Elemental Chlorine Free) bleaching reduces the amount of chlorinated compounds but not fully eliminating from the effluent. The cost of replacement of new technology for the pollution control in pulp and paper industry is generally high. For this reason the pulp and paper industries follow the old bleaching techniques which cause a lot of environmental problems. To overcome this problem in a cost-effective way it is necessary to identify the nature of the problem and compounds that cause human health and environmental problems. At present bio-bleaching of kraft pulp gives better result than ECF bleaching. In the present study three different bleaching sequences are studied ODoPD1, P1P2H, and XP1P2D and the results are compared, based on physical and chemical properties. In ECF bleaching sequence ODoPD1, the amount of residual chlorine present in waste water is 110ppm which contains significant amount of dioxins. To reduce this amount, replace chlorine dioxide stage (Do) with enzymatic bleaching (X). In this sequence XP1P2D, the addition chlorine dioxide is reduced to 1.2% and the amount of residual chlorine is 10ppm. [ABSTRACT FROM AUTHOR]

Due to its unique properties, nano fibrillated cellulose (NFC) has been a popular topic of research in recent years. Nevertheless, literature assessing environmental impacts of NFC production is scarce, especially for using other starting materials than wood pulp. Hence, in this study, a new approach of cascaded use of manure to produce biogas and subsequently use the cellulose containing digestate for NFC production (manure scenario) is compared to the production from Kraft pulp from hardwood chips (wood chips scenario) via life cycle assessment (LCA). To produce comparable outputs (NFC and biogas) in both scenarios a typical Austrian biogas plant with maize silage and pig slurry as input material is included in the wood chips scenario. A proxy approach is used to upscale the manure scenario from laboratory to an industrial scale (except for the pulp to NFC step) to ensure comparability of both scenarios. The impact categories global warming potential (GWP), fossil resource scarcity, freshwater eutrophication, human toxicity, terrestrial acidification (TAP) and terrestrial ecotoxicity potential are analysed referring to the functional unit of 1 kg NFC. Results show that the manure scenario has at least 45% lower impacts in all assessed categories. GWP is 4.41 kg CO 2 eq./kg NFC in the manure and 9.74 kg CO 2 eq./kg NFC in the wood chips scenario. The transformation step from pulp to NFC is identified as environmental hotspot due to the high electricity demand in both scenarios. Results are additionally assessed only for the industrial scale part (includes biogas and pulp production). In the latter the main difference can be found in the substrate production. While it plays a subordinate role in the manure scenario (up to 8%) as manure is seen as a waste stream with no upstream environmental impacts attached, the production of maize silage is one of the hotspots in the industrial part in the wood chips scenario. This difference is especially prominent in TAP, where the substrate production is responsible for 91% of the 0.06 kg SO 2 eq. impact, which is tenfold the impact of the manure scenario. This underlines the issue of using energy crops as substrate in biogas plants. It also highlights the importance of further research of using waste streams as inputs for the electricity production and subsequent use in the pulp and paper industry. This LCA demonstrates that NFC production from manure is a sustainable alternative to the production from hardwood Kraft pulp. [Display omitted] • Environmental impacts of nano-cellulose from manure are 45–83% lower than from wood. • Climate change impact is 55% lower in the manure than in the wood chips scenario. • Conversion from pulp to nano-cellulose is a hotspot due to high electricity demand. • Nano-cellulose from manure is a sustainable alternative to wood chips. [ABSTRACT FROM AUTHOR]

In this study, cationic starch (CS) was added to softwood kraft pulps at different degrees of beating in order to evaluate their effects on the strength properties of the pulp. Handsheets were prepared by using three levels of CS addition (0.75, 1.5, and 2.25% CS with respect to oven-dry pulp) to kraft pulps at different beating degrees (15, 20, 25, and 30° SR). It was found that the tensile and burst indices improved with beating, CS addition, and a combination of these two applications, while the tear index decreased. Remarkable increases in burst and tensile indices were achieved with a 0.75% addition of CS to 15° SR and 20° SR pulps, while notable decreases in tear index was obtained at the same conditions. A gradual tendency was observed in higher beating degrees (25° SR and 30° SR) and higher CS additions (1.50 and 2.25%). [ABSTRACT FROM AUTHOR]

Hemicelluloses extracted prior to kraft pulping can subsequently be introduced as wet-end strength additives in a papermaking process. The 4- O-methyl glucuronoxylan (Me-GluX) extracted from Eucalyptus grandis (E. grandis) under mild alkaline conditions was cationized and added to bleached kraft pulp (BKP) from E. grandis before refining. The cationization by 2,3-epoxypropyltrimethylammonium chloride (ETA) was done in a central composite designed experiment. Me-GluX with an average molecular weight of 52,000 g mol-1 contained 27% Klason residue. The cationic Me-GluX had degrees of substitution of the cationic side chain between 0.05 and 0.73 and uronic acid content between 6.1% and 12.7%. The cationic Me-GluX as a wet-end strength additive was compared to cationic starch (CatStarch 134) in handsheets. The handsheets with cationic Me-GluX showed improvement in tensile, burst, and tear indices and had lower air permeability than those with CatStarch 134 at dosages between 1.0% and 2.0%. Accordingly, cationized Me-GluX is a potential green wet-end strength additive, which could fully or partially replace the synthetic and starch additives. [ABSTRACT FROM AUTHOR]

Fibrillation of chemical and mechanical pulps with different lignin contents was studied. The pulps were ion exchanged into their sodium form prior to fibrillation and fibrillated with an increasing level of energy using high-shear friction grinding. The fibrillated samples were characterized for their chemical composition, morphology, rheological properties, and water retention capacity. All pulps had a distinct tendency to form fibrillated material under high shear and compression. The lignincontaining kraft pulps fibrillated easily, and the resulting material can be utilized in applications where high viscosity, water retention capacity, and reinforcement are desired. Fibrillation of mechanical pulps resulted in more heterogeneous samples, which included fiber fragments, branched fibrillar structures, and flake-like particles. This material showed relatively low viscosity and water retention capacity when compared to the samples made from kraft pulps. Chemi-thermomechanical pulp (CTMP), when used as the raw material, yielded a more homogeneous organic filler-like material than did thermomechanical pulp (TMP). [ABSTRACT FROM AUTHOR]

The hypothesis has been tested that a carboxymethyl hemicellulose improves more effectively the dry strength of papers than a native hemicellulose. To that end, β- d-glucan from oat was treated with an alkaline ethanolic solution of sodium chloroacetate for different times to obtain a range of carboxymethylated β- d-glucan (CM-glucan) samples. The derivatization was confirmed by Fourier transform infrared spectroscopy and elemental analysis. The physical properties of paper concerning burst and tensile strength as well as folding endurance were essentially improved if CM-glucan was added to unbleached kraft fiber suspension from pine before papermaking. The effects could be maximized by a proper selection of carboxymethylation time and the amount of CM-glucan added to the suspension. The effect was also beneficial in the case of recycled fibers. [ABSTRACT FROM AUTHOR]

Different enzymatic strategies were applied to improve lignin and hexenuronic acid (HexA) removal. Three laccases (L) with different redox potentials were applied in combination with 1-hydroxybenzotriazole or methyl syringate to softwood sulfite and hardwood kraft fibers. The enzymes with a high-redox potential from Pycnoporus cinnabarinus and Trametes villosa were found to be the most efficient. The bleaching efficiency was not significantly influenced by the presence or absence of HexA in the different types of lignocellulosic fibers. Subsequently, the lignin or HexA removal in the presence of different mediators was evaluated in eucalyptus fibers with the T. villosa laccase (TvL). Natural mediators removed only lignin, whereas the combinations of TvL with synthetic mediators removed both HexA and lignin. The mediator violuric acid (VA) was the most efficient as judged by the properties of fiber and effluent. A xylanase pretreatment stage was found to boost the access of the LVA system to HexA without affecting lignin in the pulp. [ABSTRACT FROM AUTHOR]

Abstract: 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 10 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 semi-chemical (NSSC) pulp. Both elementary 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 940NmL CH4 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 six 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%. [Copyright &y& Elsevier]

This study compares the suitability of using birch kraft pulp or softwood kraft pulp in the preparation of TEMPO-oxidized pulp, MFC and superabsorbent foam. TEMPO oxidation was performed using five different dosages of primary oxidant. The time of disintegration treatment was varied to study its influence on the properties of the produced MFCs and foams. Both the birch and the softwood pulps could be used for producing superabsorbent foams, depending on the process conditions, the absorption capacities were about the same for the two pulps and varied between 25 and 55 g saline solution/g absorbent. The foams based on birch pulp had, however, on average, 30 % higher retention capacity than the foams based on softwood pulp. The maximum retention capacity obtained was 16.6 g saline solution/g absorbent. The greater retention capacity of birch-based foams is not fully understood, but a smaller pore size may be the reason, which in turn would generate greater capillary forces. In addition to this, it was found that birch pulps, contrary to softwood pulps, had a substantial amount of fibers that were relatively unaffected by the disintegration treatment. These oxidized fibers are likely to reinforce the foam, thereby making the foam more resistant to external pressures, which is in accordance with earlier findings. [ABSTRACT FROM AUTHOR]

Xylanases can boost pulp bleachability in Elemental Chlorine Free (ECF) processes, but their industrial implementation for producing bleached kraft pulps is not straightforward. It requires enzymes to be active and stable at the extreme conditions of alkalinity and high temperature typical of this industrial process; most commercial enzymes are unable to withstand these conditions. In this work, a novel highly thermo and alkaline-tolerant xylanase from Pseudothermotoga thermarum was overproduced in E. coli and tested as a bleaching booster of hardwood kraft pulps to save chlorine dioxide (ClO 2 ) during ECF bleaching. The extremozyme-stage (EXZ) was carried out at 90 °C and pH 10.5 and optimised at lab scale on an industrial oxygen-delignified eucalyptus pulp, enabling us to save 15% ClO 2 to reach the mill brightness, and with no detrimental effect on paper properties. Then, the EXZ-assisted bleaching sequence was validated at pilot scale under industrial conditions, achieving 25% ClO 2 savings and reducing the generation of organochlorinated compounds (AOX) by 18%, while maintaining pulp quality and papermaking properties. Technology reproducibility was confirmed with another industrial kraft pulp from a mix of hardwoods. The new enzymatic technology constitutes a realistic step towards environmentally friendly production of kraft pulps through industrial integration of biotechnology.