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Anaerobic treatment of cellulose bleach plant wastewater: chlorinated organics and genotoxicity removal
Chaparro, T. R.;Pires, E. C.;
Brazilian Journal of Chemical Engineering , 2011, DOI: 10.1590/S0104-66322011000400008
Abstract: this study assessed the removal efficiency of organic matter and how it relates to the decrease of toxic and mutagenic effects when an anaerobic reactor is used to treat the bleaching effluent from two kraft pulp mills. parameters such as cod (chemical oxygen demand), doc (dissolved organic carbon), aox (adsorbable organic halogen), asl (acid soluble lignin), color, chlorides, total phenols and absorbance values in the uv-vis spectral region were measured. the acute and chronic toxicity and genetic toxicity assessments were performed with daphnia similis, ceriodaphnia sp. and allium cepa l, respectively. the removal efficiency of organic matter measured as cod, ranged from 45% to 55%, while aox removal ranged from 40% to 45%. the acute toxic and chronic effects, as well as the cytotoxic, genotoxic and mutagenic effects, decrease as the biodegradable fraction of the organics is removed. these results, together with the organic load measurement of the effluents of the anaerobic treatment, indicate that these effluents are recalcitrant but not toxic. as expected, color increased when the anaerobic treatment was applied. however, the colored compounds are of microbial origin and do not cause an increase in genotoxic effects. to discharge the wastewater, it is necessary to apply a physico-chemical or aerobic biological post-treatment to the effluents of the anaerobic reactor.
Pedro R. Meza,Fernando E. Felissia,Maria Cristina Area
BioResources , 2011,
Abstract: The aim of this work was to study the effect of ozone, either alone or combined with an activated sludge system, on the reduction of the recalcitrant COD in the effluent of a chemimechanical pulping (NaOH -Na2SO3) integrated mill. Several alternative schemes involving ozonation were tested on liquors and effluents of the pulp mill, and on two kinds of effluents were taken at different points of an activated sludge pilot plant. The largest decrease in COD was 33%, whereas that in aromatic compounds (absorbance at 232.5 nm) was of 73%. The most obvious result of the ozone treatment was effluent decolorization. It was not possible to use ozonation as tertiary treatment, as ozone was necessary to treat the BOD generated, and therefore the effluent must necessarily pass through a biological treatment. With a scheme including an intermediate ozonation between two secondary treatments (post-activated sludge and pre-aeration lagoon), the maximum reductions achieved were of 70% in COD, of 93% in aromatics, and of 96% in color.
Influence of bleaching technologies on the aerobic biodegradability of effluents from Eucalyptus kraft pulps factories
Vidal, Gladys;Soto, Manuel;Méndez, Ramón;Lema, Juan Manuel;
Brazilian Archives of Biology and Technology , 1999, DOI: 10.1590/S1516-89131999000300009
Abstract: aerobic biodegradability of effluents from different eucalyptus kraft pulp bleaching processes was studied. bleaching effluents were obtained from: i) chlorine bleaching (cb) processes, with partial substitution of chlorine by chlorine dioxide and ii) total chlorine free (tcf) processes. the overall biodegradability, in terms of chemical oxygen demand (cod) was higher for tcf effluents (96-98%) than for cb ones (82-93%). taking into account the higher organic load of cb effluents, this fact implied a much higher residual cod for them (100-180 mg/l) than for tcf effluents (10-30 mg/l). furthermore, a refractory fraction of molecular weight higher than 43,000 da was found in cb effluent, which implied the necessity of a further specific treatment. the toxicity was completely removed after the biological treatment
Application research on kraft wood pulp bleaching with xylanase pretreatment

Wang Zhihui,SongQianwu,

环境工程学报 , 2007,
Abstract: Based on the practical operation data, the analysis of the pulp quality, the main material consumption and the wastewater pollutants with or without xylanase pretreatment in one kraft wood pulp mill was done. The results showed that the pulp quality could be significantly improved, the per unit consumption of wood, chlorine dioxide and energy could be sharply reduced and the pollutant loads of the bleaching wastewater could be cut down with xylanase pretreatment under the unchanging operation parameters. It is a practical bleaching process which could decrease the pulp production cost and preserve the water environment.
Risto I. Korpinen,Pedro E. Fardim
BioResources , 2009,
Abstract: Bleached unrefined and refined sawdust kraft pulps were added to bleached Norway spruce thermomechanical (TMP) and pressurised groundwood (PWG) pulps in different proportions. Handsheets were prepared and tested for physical properties. In addition, economic calculations were done to estimate the production costs of different bleached pulps in Finland. It was found that the addition of unrefined and refined sawdust kraft pulp improved drainability of the mechanical pulps. Tear strength of PGW furnishes was increased when either unrefined or refined sawdust pulp was added. Tear strength of TMP furnishes was not influenced when different sawdust kraft pulps were added. Up to 30 % of unrefined sawdust kraft pulp could be added and no significant negative effect was observed in TMP and PGW furnishes. On the other hand, when refined sawdust kraft pulp was added into the mechanical pulp furnishes, a clear improvement in the tensile strength was observed. According to the economic calculation the production cost of bleached sawdust kraft pulp is almost as low as the production cost of bleached mechanical pulp. We suggest that economically viable sawdust kraft pulp can be used as a substituent for expensive long fibre reinforcement kraft pulp in the production of mechanical pulp based papers.
Pulp and paper production from Spruce wood with kraft and modified kraft methods
A Tutus, S Ates, I Deniz
African Journal of Biotechnology , 2010,
Abstract: In this study, kraft and modified kraft pulping methods were applied for spruce (Picea orientalis) wood collected from the Black Sea Region of Turkey. Fiber properties, carbohydrate contents, strength and optical properties of resultant paper were included to determine the properties of these pulp samples. Optimum kraft, kraft-borohydride (NaBH4), kraft- anthraquinone (AQ) and kraft-ethanol pulping conditions were determined. After determining screened yield, kappa number, viscosity, fiber length, fiber coarseness, α-cellulose, holocellulose, lignin and ash content, breaking length, tear indexes and burst indexes of the obtained pulp samples, the differences of SEM image of each pulp sample were captured and evaluated. The results indicated that kraft-AQ pulps from spruce wood exhibited better characteristics than the other pulp samples with lower kappa number, higher paper strength properties and optical properties. However, kraft-NaBH4 method gave pulps with closer characteristics to kraft-AQ and also gave a higher screened yield and α-cellulose ratio than the others.
Aerobic removal of stigmasterol contained in kraft mill effluents
Chamorro,Soledad; Xavier,Claudia Regina; Hernández,Victor; Becerra,José; Vidal,Gladys;
Electronic Journal of Biotechnology , 2009,
Abstract: kraft mill effluent, due to its organic matter content and acute toxicity, must be treated. a primary treatment followed by a secondary treatment is the most common system. aerated lagoon is also considered an effective biological treatment, although this technology has some drawbacks related with operation parameters and land extension space. moreover, the recovery efficiency for micropollutants contained in kraft mill effluent is questioned due to the anoxic zone in the system. the goal of this work is to evaluate the performance of the aerated lagoon to remove stigmasterol contained in kraft mill effluents. kraft mill effluent was treated by an aerated lagoon (al), which was operated with three different stigmasterol load rates (slr = 0.2, 0.6 and 1.1 mg/l x d) and a hydraulic retention time of 1 day. the al’s maximum chemical oxygen demand (cod) removal was 65%, whereas the biological oxygen demand (bod5) was around 95%. the removal efficiency of stigmasterol removal was 96% when slr 1.1 mg/l x d, although an accumulation of stigmasterol was detected for lower slr.
Guanglei Zhao,Ronald Lai,Xiaofeng Li,Beihai He
BioResources , 2010,
Abstract: Non-wood fibers such as bamboo and wheat straw have been playing important roles in the pulp and paper industry in China. In this study an ECF-bleached bamboo kraft pulp was compared with a bleached softwood kraft pulp (NBSK) as the reinforcement pulp in fine paper production. Areas that were examined include the refining of pure fibers, influence of bamboo on dewatering, retention, and sizing. The influence of bamboo kraft pulp as a part of a furnish replacing NBSK was compared as well. Results show that fiber shortening was more prominent with bamboo when refined. This resulted in a higher amount of fines, and addition wet-end chemicals may be required to compensate. Handsheets with bamboo as a reinforcement fiber showed similar mechanical and optical properties to handsheets containing NBSK.
Paul Ander,Lars Hildén,Geoffrey Daniel
BioResources , 2008,
Abstract: A new pulp fibre testing procedure called the HCl method was used to compare different spruce and pine fibres and mixtures of these fibres to calculate number of fibre cleavages in dislocations and other weak points. This method was compared with treatment of softwood kraft pulp fibres using different cellulase mixtures. The HCl method can distinguish between mill- and laboratory-made softwood kraft pulp fibres from the same wood batch. The sugar release is characterized by xylose and other hemicellulose sugars and little glucose. This is in contrast to cellulases, which despite strong fibre cleavage, did not distinguish between mill- and laboratory-made pulp fibres and released large amounts of glucose from the fibres. Hemicellulose degradation by HCl and deep penetration of the acid into the primary and secondary fibre cell walls at 80°C seems to be of major importance for the differentiation between mill and laboratory pulp fibres. Cellulases, in contrast, act mostly on the fibre surfaces, and deep penetration only takes place in amorphous regions of dislocations.
Properties and Application of a Partially Purified Thermoalkali Stable Xylanase from Cellulosimicrobium sp. MTCC 10645 in Kraft Pulp Bleaching  [PDF]
Rajashri D. Kamble,Anandrao R. Jadhav
ISRN Biotechnology , 2013, DOI: 10.5402/2013/872325
Abstract: The most promising application of xylanases (E.C. is in the prebleaching of kraft pulp. The present paper reports bleaching effects of a thermoalkali stable xylanase from Cellulosimicrobium sp. MTCC 10645. The bacterium produced thermo-alkali stable xylanase in a basal medium supplemented with wheat bran (1% w/v), which was optimally active at pH 7.0 and 50°C. The xylanase was stable at temperature 50°C for 1?h and retained up to 86% of the activity. The xylanase was stable in a broad pH range of 6.0–11.0 for 1?h at 50°C. Metal ions Ca+2, Hg+2, and Pb+2 were inhibitory for xylanase retaining 72.3%, 35.07% and 36.7% relative activity at 10?mM concentration, whereas Fe+2, Cu+2, Mn+2, Na+2, Co+2, and Zn+2 were inducers at concentrations of 5?mM and 10?mM. The enzyme exhibited greater binding affinity exclusively for xylans but not for avicel, CMC, cellobiose, starch, or p-nitrophenyl xylopyranoside. Parachloromercuric benzoate and iodoacetamide were found stimulatory, while potassium permanganate, cysteine, and cystine markedly reduced the activity. The xylanase dose of 2.0?U/g dry weight pulp of 10% consistency gave optimum bleach boosting of kraft pulp at pH 8.0 and temperature 50°C for 5?h reaction time. 1. Introduction The most promising application of xylanases (E.C. is in the prebleaching of kraft pulp. The pulp and paper industry is modifying its pulping, bleaching, and effluent treatment technologies to reduce the environmental impact of mill effluents. Prebleaching of kraft pulps with xylanases lowers chlorine charges, which reduce chloroorganic discharges [1–3]. Tremblay and Archibald reported the delignification of unbleached softwood and hardwood kraft pulps [4]. Thus reducing the Cl2 required to achieve a given degree of bleaching [3, 5–7]. The public concern on the impact of pollutants from paper and pulp industries, which use chlorine as the bleaching agent act as strong driving force in developing biotechnology aided techniques for novel bleaching that is biobleaching [8, 9]. The occurrence of cellulase contamination is posing a major threat in applying the xylanases in biobleaching. The cellulases easily result in the hydrolysis of cellulose, which should be the main recovered product in paper industry. However, the enzyme preparations from microorganisms producing higher levels of xylanases with no cellulase activity can be applied in paper industry because the loss of pulp viscosity is at minimum level [10]. Xylanases have been reported from bacteria, fungi, actinomycetes, and yeasts [11–14]. The use of abundantly
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