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The following report is a life cycle assessment (LCA) of pulp production process chains where the Elemental Chlorine Free (ECF) pulp production of Äänekoski bioproduct mill, the pulp production of average European Total Chlorine Free (TCF) pulp mills, as well as the pulp production of average pulp mills in Europe and Latin America are assessed.This study was commissioned by METSÄ FIBRE OY, Finland, on 23 March 2022. The main contractor to carry out the study is Fraunhofer IMWS. The report was prepared on 05 October 2022. The study was conducted according to the requirements of the International Standard DIN EN ISO 14044.

This study aimed to determine the effect of recycling elemental chlorine free (ECF) bleaching effluent (D0EpD1 and OD0EpD1) after treatment through electrocoagulation under optimum conditions on paper properties. The effect of pH, current density, time and dose of electrolyte on the reduction of chemical oxygen demand (COD) and color was studied. Maximum decrease in COD and color was found under optimum conditions (i.e., pH 7, treatment time of 30 min, current density of 29.16 mA/cm2, and 1 g/L NaCl). Under these optimum conditions, the reduction in COD and color was of 79.9% and 99.10%, respectively. The reduction in the strength properties of paper, caused by recycling, was found to be insignificant, but a decline of 2.11% for D0EpD1 and of 1.43% for OD0EpD1 in brightness was found. Using the electrocoagulation method to treat the bleaching effluent can prove to have valuable potential towards wastewater utilization, pollution control, and sustainable development of the industry.

Hardwood kraft pulp contains relatively high hexenuronic acid content which increases unnecessary consumption of bleaching chemicals and has negative effects on pulp brightness stability. Hexenuron...

The increasing consumption of pulp for chemical processing, including production of sanitary tissue products and other medical products, food packaging, as well as fillers for food products leads to new requirements for the quality of raw materials. The task of improving the characteristics of pulp has become particularly acute in connection with the COVID-19 epidemic: the demand for disposable nonwoven materials in direct contact with the human skin has increased several times over. The elemental chlorine free (ECF) sulfate pulp bleaching process, which uses chlorine dioxide as a bleaching agent, dominates bleached pulp production worldwide. The chlorine-containing compounds formed as a result of bleaching pollute not only waste water, but also the product itself. In the near future, it is expected that paper products made with chlorine-based bleaches may be banned for the production of sanitary tissue products and food packaging. If the products of the pulp and paper industry do not meet international consumer requirements, the pulp market for these purposes may face undesirable results. The most promising direction of modernization the existing bleaching schemes, both in terms of the process consumption parameters and the quality of the produced pulp, is the use of oxygen-alkaline bleaching in the first stage. Determination of total and organically bound chlorine content in pulp materials in accordance with ISO 11480:2017 on the advanced plant has shown, that the introduction of bleaching schemes using oxygen-alkaline agents will ensure the recommended content of chlorine compounds while maintaining the necessary characteristics of pulp for the manufacture of medical and sanitary tissue products, food packaging. However, high quality of finished products that meet consumers’ requirements is possible only if the chlorine content is controlled at all stages of pulp production, since the quantitative indicators of this substance content remain close to the upper allowable limit. For citation: sofronova e.D., Lipin v.A., Dubovy v.K., Sustavova t.A. Minimizing the Chlorine Content in bleached sulfate pulp for sanitary tissue products and food packaging. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 3, pp. 186–195. DOI: 10.37482/0536-1036-2021-3-186-195

Effect of using ozone before elemental chlorine free (ECF) bleaching of oxygen delignified wheat straw pulp produced following soda-anthraquinone pulping on bleaching effluent and pulp properties was studied. The effluent generated during bleaching of pulp contains high amount of adsorbable organic halogens (AOX), chemical oxygen demand (COD), biochemical oxygen demand (BOD) and highly toxic chlorophenolic compounds. This study is aimed to utilise green chemistry approach during bleaching of one of the abundantly used agro residue wheat straw for improving the quality of bleaching effluent and pulp properties. Introducing ozone stage before ECF bleaching resulted in significant reduction of chloriphenolic compounds like chlorocatechols by 48.9 %, chloroguaiacols by 33.3 %, chlorovanillins by 28.4 % and chlorophenols by 26.7 % in the effluent compared to those of control. Incorporation of ozone before ECF bleaching BOD, COD, AOX and colour were reduced by 40.0 %, 41.1 %, 46.7 % and 57.8 %, respectively, as compared to control. Optical properties like brightness and whiteness of the pulp bleached using ozone were also improved by 2.5 units and 4.0 units, respectively as compared to that with control.

Recently, a new type of bleaching sequence, Elemental Chlorine Free (ECF) light with one D stage, has been developed. It combines the efficiency and high selectivity of chlorine dioxide (ClO2) bleaching with more environmental friendly oxygen based bleaching chemicals. This work examines the effect of pH on the formation of adsorbable organically bound halogens (AOX) in an intermediate D stage – a single ClO2 stage at the middle of an ECF light bleaching sequence. Carbon dioxide (CO2) is used to generate a bicarbonate buffer in situ, stabilizing the pH during the bleaching. Near-neutral pH is hypothesized to decrease the formation of strongly chlorinating species, so that the AOX formation is reduced. The results indicate that a near-neutral pH D stage can reduce the AOX content in the effluents with up to 30%. The ISO brightness was unchanged to a lower ClO2 consumption. The pulp viscosity was slightly higher after near-neutral pH D stage, but to its disadvantage a lesser delignification and removal of HexA was obtained. The degradation of HexA correlated well with the AOX, affirming earlier theories that HexA has a major impact on the AOX formation. The higher amounts of residual HexA and lignin resulted in more thermal yellowing of the pulps bleached with a near-neutral pH D stage.

Grasses have emerged as potential alternative raw materials which can replace wood for pulp and paper products. Various species of grasses have been explored previously for pulp and paper production. This study is aimed to investigate pulp and papermaking characteristics of a grass species namely Cymbopogon winterianus Jowitt which is commonly known as citronella grass. This grass was subjected to proximate chemical characterisation; fibre morphology analysis; soda, soda-AQ (soda-anthraquinone), and kraft pulping; elemental chlorine free bleaching using D0EPD1 (D = ClO2 in acidic medium; EP = alkaline extraction with addition of H2O2; 0 and 1 = initial and final stage) sequence; and evaluation of physical strength properties of paper hand sheets. The pulp and paper hand sheets were also examined through SEM (scanning electron microscope) and FTIR (Fourier-transform infrared) spectroscopy to observe the structural and functional group variations. The proximate chemical analysis of citronella grass was found superior in terms of α-cellulose (38.10%), pentosans (22.30%) and alkali solubility (28.20%) while inferior in terms of ash (8.20%), lignin (25.10%) and alcohol benzene solubility (6.31%) with respect to some other grass species used for pulp and papermaking. Fibre length (0.69–0.74 mm) and fibre width (13.8–15.1 μm) were also comparable to other grass species. Brown pulp characteristics such as screened yield (44.67%), brightness (~24 %ISO) and kappa number (~20) revealed superiority of soda-AQ pulping among all the pulping processes while the kraft pulp exhibited the highest brightness (83.05 %ISO) and intrinsic viscosity (17.6 cP) after D0EPD1 bleaching. Tear index, tensile index and burst index of paper hand sheets obtained from bleaching of soda-AQ and kraft pulps were almost similar but higher to that of bleached soda pulp. The citronella grass was found suitable for producing writing and printing grade paper based on processes and optimised parameters described in this study.

Production of nanocellulosic materials from loblolly pine (Pinus taeda) kraft pulp provides an opportunity to diversify the portfolio of traditional pulp and paper industries. In this study, pinewood was first subjected to dilute acid pre-extraction with 0.5% sulfuric acid in order to fractionate the hemicellulose, followed by kraft pulping and elemental chlorine free bleaching in order to obtain up to 97% pure cellulose fractions. CNCs (cellulose nanocrystals) were prepared by hydrolyzing the bleached kraft pulp with 64% sulfuric acid at 45 °C for 30 min; the resultant unhydrolyzed solid residues were homogenized using a microfluidizer in order to produce cellulose nanofibers (CNFs). The dilute acid pre-extraction step resulted in complete hydrolysis of galactan and arabinan from pinewood, as well as in partial removal of mannan (80%) and xylan (58%). As a result of pre-extraction, the CNC yield and crystallinity improved by 44% and 11%, respectively, from the corresponding kraft pulps. CNCs produced from the pre-extracted materials also exhibited 16% reduction in particle size, but a 70% increase in sulfur content as well as 20% increase in zeta potential. Higher purity of kraft pulps resulted in higher exposure of cellulose crystalline domains to sulfuric acid thereby resulting in the observed changes. Thus, pulp purity was found to play a significant role in determining the quantity and quality of nanocellulosic materials derived from loblolly pine.

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...

Industrialization and urbanization are the key drivers to threaten the environmental quality and natural resources. Traditionally, pulp and paper industry has been highly reliant on forest based resources for its escalation. Shortage of forest based raw materials, strict environmental regulations and policies have compelled the industry to seek for alternate raw materials for its production. Mills are now focusing on exploring the potential of different agro wastes such as cereal straws and bagasse etc. In present research, sugarcane trash, one of the most abundant agro residues in India, was investigated for its capability in pulping and bleaching. Chemical characterization of sugarcane trash showed that it contains 40.4% cellulose, 33.2% hemicelluloses, 17.4% lignin and 6.45% ash content with 2.76% silica. To cook sugarcane trash with soda pulping method, 14% alkali charge, 15 min time and 162 °C temperature was found to be optimum and pulp of kappa no. 19.8 was prepared that exhibited good strength properties. Bleaching of pulp was carried out using elemental chlorine (Cl2), hypochlorite and chlorine dioxide (ClO2) based sequences. Replacement of Cl2 with ClO2 has significant impact on strength properties and effluent characteristics. Oxygen delignification stage was incorporated prior to ClO2 that resulted in improved optical properties of pulp with noticeable reduction in wastewater load. This paper elaborates the need of using sugarcane trash in paper mills with environment friendly pulping and bleaching processes to combat with the problem of waste management, wastewater load reduction during bleaching and substitute for wood based raw materials in papermaking.

In this study, the visible-light-induced intimately coupled photocatalysis and biodegradation (ICPB) technology was fabricated using the TiO2/bagasse cellulose composite as the carrier and Phanerochaete mixed activated sludge as the biological source. The ICPB degradation effect of elemental chlorine free (ECF) bleaching wastewater was evaluated via the response surface design. Then, the wastewater was characterized, including absorbable organic halogen (AOX), dissolved organic carbon (DOC), chemical oxygen demand (COD), chroma, pH, suspended solids, and the organic compound changes in wastewater were analyzed by fourier transform infrared spectroscopy (FT-IR). Under the optimal conditions of pH 7, carrier filling rate of 5%, aeration rate of 2 L/min, and reaction time of 7 h, the degradation efficiencies of AOX, COD, and DOC were 95%, 91%, and 82%, respectively. The X-ray photoelectron spectroscopy (XPS) results of the ICPB carrier after the reaction were almost identical to those before the reaction. The biomass and its activity on the ICPB system were analyzed by the dominant bacteria during degradation (Curaneotrichosporon, Paenibacillus, Cellulonas, Phanerochaete, Dechlorobacter, Rhodotorula, Sphingobacterium, and Ruminiclostridium), which had a good degradation effect on wastewater. This study affords a novel method for the degradation of ECF bleaching wastewater and a new idea for ICPB technology optimization.

Steady-state models were constructed to predict the response of a southern U.S. softwood brown¬stock to three- and five-stage elemental chlorine-free (ECF) bleach sequences. The models provided insight into how typical (EO) washing efficiencies from a vacuum drum unit affected pulp brightening and total chlorine dioxide con¬sumption. When (EO) carryover was between 15% and 30%, the chlorine dioxide needed to reach target brightness increased by 8% to 15% for the D0(EO)D1(EP)D2 sequence (89% ISO) and by 15% to 23% for the D0(EO)D1 sequence (86% ISO) versus perfect washing. Use of (EO) filtrate as D0 shower water, such as in split-flow countercurrent wash¬ing, caused the bleach uptake to increase by 1.5 to 3.0 kg chlorine dioxide (ClO2)/ton pulp when compared to using cleaner D0 shower water sources. The ClO2 consumed by 15% to 30% (EO) washer carryover is comparable to that consumed by typical carryover levels from brownstock washing (~10 kg Na2SO4/ton pulp). High (EO) carryover made ECF bleaching to higher brightness targets more difficult.

In this study, an elemental chlorine free (ECF) bleach plant with a D0(EOP)D1(EP)D2 sequence was studied with the aim of identifying options for significantly decreasing (fresh) water usage in the bleach plant and decreasing the effluent volume. A base-case simulation model for a softwood kraft market pulp mill was made based on a reference model representing the best available techniques as well as data produced in an extensive laboratory pulp bleaching study. This model was used to evaluate increased closure within the bleach plant and the recirculation of bleach plant effluent to the brownstock system and their effects on both the bleach plant and the recovery cycle. The results indicate that it is possible to reduce the fresh water consumption from 15 metric tons/a.d. metric ton in the base case to about 2 metric tons/a.d. metric ton, without increasing the carryover of chemical oxygen demand (COD) to the pulp machine. Nonprocess elements in wood contribute to the levels of metals found in the bleach plant and thus to the risk of precipitates such as calcium oxalate, barium sulfate, and calcium carbonate. The risk of precipitates forming is a key factor determining the possible degree of closure. In addition, chloride concentration in the black liquor is another important factor that is affected by recirculating bleach plant filtrate to the brownstock washer and by the grade of the sodium hydroxide used in the mill.

This study evaluated the suitability of old corrugated containerboard (OCC) to be upcycled into a high-quality pulp for tissue paper manufacture. The evolution of the physicochemical properties of OCC fibers and their effect on tissue properties were tracked across each stage of two elemental chlorine free (ECF) bleaching sequences. The properties of bleached OCC were compared to those of deinked pulp (DIP), southern bleached softwood kraft (SBSK), and refined OCC unbleached. Both sequences reduced the kappa number from 89 to negligible values and increased brightness from 18.9% to ca. 75% ISO, on average 6.2% ISO units below that of DIP. Overall, bleaching significantly increased tensile index and absorbency rate while having adverse effects on bulk and softness and minor impacts on absorption capacity. The change in properties was correlated to the improved fiber bondability and fiber wettability derived from the lignin removal. Compared to DIP, bleached OCC exhibited a higher tensile index, higher freeness, and similar absorption capacity but lower softness. It also showed higher absorption capacity and similar softness than SBSK but lower freeness at a comparable tensile index. The results indicate that upgraded OCC could be used as an alternative fiber to address the forecasted shortage of high-grade recycled papers in recycled tissue grades or replace virgin fibers in producing virgin tissue grades. In addition, it was determined that refined OCC unbleached could also be suitable for use in tissue grades where high brightness is not an essential product feature.

This paper illustrates the need of using the agro waste (wheat straw) as a substitute for forest products in paper industry. It aims on using the soda-AQ pulping process for converting waste to fibrous pulp. Further, it emphasizes on use of chlorine dioxide in place of elemental chlorine and hypochlorite during bleaching with aim of reducing the wastewater load and improving the pulp quality. Complete chemical characterization of wheat straw was performed. The soda-AQ (anthraquinone) method was opted for cooking and to make a pulp of kappa number 13. The pulp was bleached with elemental chlorine and calcium hypochlorite based sequences. To study the impact of adding chlorine dioxide on paper properties and effluent quality, elemental chlorine and hypochlorite were replaced with dioxide. The total elemental chlorine free bleaching sequence was also studied. The hand sheets were prepared to analyze the bleached and unbleached pulp properties using standard methodology. The effluent quality was studied by measuring the properties COD, BOD, TDS, TSS, TS, colour, lignin and adsorbable organic halides. Proximate chemical analysis of wheat straw showed that it contains holocellulose 67.3 ± 0.16%, hemicelluloses 39.2 ± 0.7%, cellulose 34.2 ± 0.9%, lignin content 14.9 ± 0.09% and ash 9.2% that mainly composed of silica (7.7%). With soda-AQ process a pulp with 53% yield and good strength properties was obtained. The bleached pulp of chlorine dioxide based sequences was having better strength properties in comparison to chlorine based sequences. Total replacement of elemental chlorine with chlorine dioxide reduced the BOD (52%), COD (49%), colour (43%), lignin (57%) and AOX (63%). Research concluded that wheat straw can be utilized by paper mills to combat the problem of waste management, air pollution due to its burning and issues of raw material for papermaking. Soda-AQ pulping method was found to be effective for preparing the wheat straw pulp. Use of elemental chlorine free bleaching may prove to be a reliable approach for better environmental management with high pulp characteristics.

The factors governing the brightness reversion (BR) of dissolving pulps under heat exposure are investigated. Carbonyl (CO) groups were artificially introduced on fully bleached pulp by sodium hypochlorite (NaClO) oxidation. It was demonstrated that the CO groups are responsible for loss of brightness stability (BS). These groups were partly eliminated by an alkaline extraction stage (E), which improved BS. However, an alkaline peroxide stage (P) was more efficient than E to improve BS, but without any additional CO loss. Moreover, an unbleached dissolving pulp was bleached in the laboratory by elemental chlorine free (ECF) and totally chlorine free (TCF) [ozone-based] sequences to the same brightness. The very low CO content was about the same in both cases. The ECF-bleached pulp showed substantially lower BS than the TCF pulp. These results are interpreted such that the chemistry of chromophores in the unbleached pulp also governs BS. In situ detection of phenolic and quinone chromophores in bleached dissolving pulp was performed by electron paramagnetic resonance (EPR) spectroscopy and ultraviolet resonance Raman (UVRR) spectroscopy. The content of these groups was bleaching-sequence-dependent, which may be related to the BS differences.

The toxicity of eighteen different untreated or secondary treated TCF (total chlorine free), ECF (elemental chlorine free) and conventional (Cy bleaching effluents was assessed by a battery of biological tests. The toxicity tests used were: Pseudomonas putida growth inhibition test, Vibrio fisheri luminescence bacteria test, Selenastrum capricornutum algal growth inhibition test, Daphnia magna mobility inhibition (24 h) test and Brachydanio rerio zebra fish hatching and survival test. In the P. putida growth inhibition test only conventional bleaching effluents and ECF birch pulp effluent gave a slightly toxic response. The V. fisheri test was more sensitive. The EC50 values of most untreated ECF and TCF effluents were under 10% effluent concentrations (conventional effluent 15%) and secondary treated effluents were not toxic. All untreated bleaching effluents gave a toxic response in S. capricornutum algal test. EC50 values varied between 12 and 46% effluent concentrations. Treated effluents were not toxic and had a stimulative impact on algal growth. The results obtained by the D. magna test showed that effluents of TCF, ECF (birch pulp) and conventional (pine pulp) bleaching were equally toxic (LC50 values about 40%). Untreated TCF and ECF (pine and mixed pine and birch pulp) like secondary and pilot treated effluents were all nontoxic. The results obtained by the egg/larvae test of zebra fish showed that the lowest effect concentration (LOEC) values differed between hatching and mortality of the larvae. Some effluents were more harmful to hatching while others had a greater effect on mortality. Secondary treated effluents did not have any significant effects. Of the untreated effluents, TCF and conventional (both pine pulp) were the most toxic (LOEC values of hatching between 1 and 3.2% and mortality between 12 and 6.8%). The effects of all the other samples were nearly the same (LOEC values varying between 5 and 25%). There was no significant difference in toxicity between untreated conventional, ECF and TFC bleaching effluents. The natural constituents of wood are probably responsible for the toxicity observed in ECF and TCF effluents.

Six elemental chlorine-free bleaching sequences were studied to see their effect on quality of pulp produced and quantity of pollutants generated during bleaching of wheat straw soda pulp. Impact of parameters like adsorbable organic halogens (AOX), chemical oxygen demand (COD), biochemical oxygen demand (BOD) and sodium adsorption ratio, pH and total dissolved solids generated during bleaching on environment as index of global pollution (IGP) was also studied. The purpose of the study was to investigate six elemental chlorine-free bleaching sequences to compare the pulp quality, effluent properties and their impact on environment. An oxygen delignification stage before D0EOPD bleaching sequence reduced the AOX, COD, colour and BOD by 44%, 42%, 36% and 33%, respectively, whereas an ozonation stage before bleaching reduced the same by 70%, 66%, 73% and 60%, respectively, as compared to those of control. The generation of pollutants as AOX, COD, colour and BOD was reduced further by 88%, 80%, 90% and 77%, respectively, with the use of short bleaching sequences (DD, DP and PD) as compared to those of control. The environmental impact as IGP with D0EOPD bleaching sequence was 2.65 which got reduced to 1.44 with bleaching sequence OZPD. Bleaching sequence OZD0EOPD was found the most effective for improving brightness and whiteness of the pulp, whereas short bleaching sequence OZPD found the most effective for reducing generation of pollutants during bleaching among different bleaching sequences studied.

This investigation is aimed to explore the pulp and papermaking potential of solid residue left after isolation of essential oil from Cymbopogon winterianus Jowitt using hydro distillation, as well as to evaluate the physical strength properties of pulp and paper produced from it. Soda, soda–AQ (soda–anthraquinone) and kraft pulping of oil isolated C. winterianus were optimized and the corresponding optimum unbleached pulp in each process was subjected to environment friendly ECF (elemental chlorine free) bleaching using D1EpD2 (D = chlorine dioxide in acidic medium; Ep = alkaline extraction with addition of hydrogen peroxide; 1 and 2 = first and second time) sequence. Fibre morphological investigation and fibre classification of bleached pulp from every optimized pulping process were also carried out. Hand sheets of bleached pulps were prepared to evaluate the physical strength properties. All the methods were followed as per standard procedures. The proximate chemical composition of oil isolated C. winterianus revealed 62.70% holocellulose, 37.62% alpha-cellulose, 21.10% pentosans and 24.10% lignin. Kraft pulping at 12% NaOH dose and 20% sulphidity produced unbleached pulp with kappa 18.72, yield 43.68%, brightness 21.36% and viscosity 32.6 cp; while bleached pulp with brightness 83.67% and viscosity 16.7 cp. However, hand sheets prepared from soda–AQ pulping exhibited tensile index 31.5 N m/g, tear index 5.02 m Nm2/g and burst index 2.20 kPam2/g which were superior to kraft pulping. Soda pulp demonstrated inferiority in quality to kraft and soda–AQ pulps. No significant differences were observed in fibre morphology of pulps from different processes while fibre classification revealed maximum useful bleached fibres 55.9% from kraft pulping. This research proved that C. winterianus solid residue left after isolation of essential oil could be a substantial source for pulp and papermaking using conventional pulping processes and ECF bleaching sequence at process conditions described in this work.

The parameters of elemental chlorine-free (ECF) bleaching (D0EpD1) of eucalyptus kraft pulp were optimized to reduce AOX formation. The optimal conditions were pulp concentration 10%, ClO2 dosage 2.8%, pH 3.5, temperature 60°C, time 60 min at D0; H2O2 dosage 1.25%, alkali dosage 2.0%, temperature 65°C, time 105 min at Ep; ClO2 dosage 0.2%, pH 4.5, temperature 60°C, time 55 min at D1. AOX formation was 0.553 kg.tp–1, each stage was 0.470 kg.tp–1, 0.060 kg.tp–1 and 0.023 kg.tp–1, respectively. Compared with un-optimized AOX formation decreased by 23.7%.The brightness and viscosity was 84.36% ISO, 834.6 mL.g–1. In fact, good quality of the pulp was obtained when AOX formation has fallen dramatically. These provide a theoretical basis for reducing the produce of AOX and realizing the clean bleaching.

A lignocellulosic non-wood material sarkanda available in abundance as waste, was evaluated for chemical constituents, pulping behavior, morphological properties, bleaching behavior and paper handsheet strength properties. Present study reveals that sarkanda contains cellulose 36.2 ± 0.5 %, hemicelluloses 35.2 ± 0.41 %, lignin 21.2 ± 0.22 % and ash 8.2 ± 0.3 %. Soda-anthraquinone pulping of sarkanda using 15 % active alkali resulted in unbleached pulp with 14.7 kappa number, 16.0 cP viscosity and 54.6 % pulp yield. With use of elemental chlorine free bleaching sequence, OD0EOPD, final bleached pulp achieved 85.7 % ISO brightness, whereas, using total chlorine free bleaching sequence, OZEOPPOPO, the brightness obtained was 81.9 % ISO. Elemental chlorine free bleached sarkanda pulp had tensile index of 39.4 N m/g, burst index of 3.4 kN/g and tear index of 5.7 mN m2/g. The study exhibits that sarkanda has potential to be utilized for papermaking. Such approach of using non-wood raw material with elemental chlorine free bleaching and total chlorine free bleaching sequences for papermaking can be a valuable approach for reducing pollutants generation, utilization of waste biomass and fulfillment of fibrous raw material requirement for paper industry.

The basic density is the main technical property of the wood due to the fact of the easy determination and correlation with the others wood properties. In this article, it was evaluated wood chips from a five-years-old Eucalyptus grandis in three different silvicultural treatments for pulp and paper production. First, a conventional kraft pulping was executed in the same conditions and then submitted to some elemental chlorine free (ECF) bleaching process to achieve the target brightness of 88 ± 1% ISO. The bleached pulps were refined in a Jokro Mill at 0, 2250, 4500 and 6750 revolutions and their physical, mechanical and optical properties were analyzed. The statistical analysis indicated a difference in the wood basic density from the different silvicultural treatments. The yield of the pulping process was not affected by the variation of the wood basic density. The denser wood had the advantage of a lower specific wood consumption while the disadvantage was a greater difficulty in the delignification and a decrease in the selectivity of the pulping process. The denser wood was the one with the best bleachability and the one that most consumed chlorine in the bleaching process. The increase of the wood density caused gains in the fisical and optical properties of the bleached pulp and losses in the mechanical properties.The optical properties of the pulps from denser woods are more resistant than the negative effects of mechanical properties. Keywords: Kraft pulping; pulp bleaching; paper properties.

The pulp and paper industry is highly dependent on forest and water resources. It has more concerns on fair utilization of these resources and their conservation for its further expansion. Present study emphasizes on the use of rice straw (agro waste) in papermaking to protect wood based resources. It further deals with ozone bleaching (Z) prior to elemental chlorine free bleaching that proved to be significant in terms of reducing the effluent load specially the reduction in toxic, recalcitrant and carcinogenic compounds. Z based sequences resulted in pulp brightness of ∼85% that was 3.6% higher than the elemental chlorine free bleaching. Bleached pulps of Z based sequences were found to be having better strength properties than elemental chlorine based sequence and thus may be adopted as improved bleaching technology. The analysis of handsheets prepared after pulp bleaching was performed using X-Ray diffraction, ATR-FTIR and SEM. Incorporating ozone stage resulted in marked reduction of 58% and 63% in total solids in bleaching wastewater. Reduction of more than 80% in BOD, COD and adsorbable organic halides was achieved in Z based bleaching in comparison to chlorine bleaching. The amount of chlorophenols, guaiacols, catechols, vanillins and syringols became negligible (approx. 90% reduction) in effluents of Z based bleaching sequences. The chlorine dioxide followed by peroxide bleaching after Z stage was found to be the most promising to reduce the effluent load.

International audience; Alkaline washed nanofibrillated cellulose (NFC) was obtained via TEMPO-mediation of hardwood pulp which had been short catalytically bleached (Hcat) under a controlled range of conditions. With careful combination of bleaching conditions, together with the subsequent alkali pre-treatment prior to TEMPO oxidation, it is possible to reduce xylan content of Hcat hardwood birch pulps as compared to traditional elemental chlorine free (ECF) bleaching. The defined amount of xylan is seen to affect the static water-holding and agglomeration state of the respective NFC. It is shown that colloidal interactions between the nanofibrils are dependent on the amount of water present in the NFC hydrogels as water retained within xylan induced swelling of the fibrils that resulted in a weaker aerogel structure.

Development of large scale commercial pulping and papermaking processes using agricultural solid residues as raw materials is ecologically and environmentally important. This paper reports pilot scale soda-anthraquinone pulping of palm oil empty fruit bunches and elemental chlorine free bleaching of resulting pulp using DEpD sequence. The physical and morphological properties of resulting bleached and unbleached pulp fibres along with yield have been determined. The pilot scale unbleached pulp exhibited brightness 31.4%, kappa number 18, viscosity 845 mL/g, tensile index 59 Nm/g, burst index 5 kN/g and tear index 7.8 mNm 2 /g with a yield of 48% and bleached pulp resulted in brightness 85%, viscosity 650 mL/g, tensile index 48 Nm/g, burst index 4.70 kN/g and tear index 9.1 mNm 2 /g. Comparison of these values with those obtained at lab scale by various researchers through different processes revealed that the operating conditions adopted in this study can be successfully implemented at a paper mill for commercial production of pulp and paper from palm oil empty fruit bunches.

BACKGROUND Organoperoxyl radicals generated from unsaturated fatty acids can initiate lignin degradation reactions. RESULTS Manganese peroxidase (MnP, EC 1.11.1.13) produced by the basidiomycete Ceriporiopsis subvermispora and biomimetic systems were explored to produce organoperoxyl radicals for lignin degradation of eucalypt wood and unbleached kraft pulps. Treatment of milled-wood with MnP–, Mn3+– or Fe2+–linoleic acid systems transformed the lignin structure and released water-soluble low molar mass aromatic fragments. Lignin transformations initiated by MnP were the most intense. Residual lignins from MnP- or Mn3+-treated wood exhibited diminished yields for thioacidolysis monomers and increased carboxyl content, suggesting β-O-4 and Cα–Cβ cleavage followed by side chain oxidation. MnP-based biobleaching of eucalypt kraft pulp corresponded to savings of 3.7 kg ClO2 ton−1 pulp during elemental chlorine free (ECF) bleaching to 88–90% brightness. Another interesting characteristic of the MnP-treated pulp was a slightly higher drainage before refining, suggesting that this pulp would require less energy during drying in industrial processes. CONCLUSION Lignin was degraded in vitro by the action of MnP and biomimetic systems initiating lipid peroxidation reactions. Application of the most reactive system, based on MnP, provided savings of 3.7 kg ClO2 ton−1 pulp during ECF bleaching to 88–90% ISO brightness. © 2015 Society of Chemical Industry

The experimental research, process design principles, and engineering practice of a bagasse pulp production line that could run both totally chlorine-free (OP)Q(PO) and elemental chlorine-free (OP)D(EOP) bleaching sequences are discussed in this paper. Under specified process conditions, the oxygen delignification rate was up to 50% and the brightness of unbleached pulp increased. The (OP)Q(PO) sequence bleached pulp had a brightness of 83.1% ISO and an intrinsic viscosity of 888 mL/g, and the (OP)D(EOP) sequence bleached pulp had a brightness of 85.7% ISO and an intrinsic viscosity of 905 mL/g. Pulp quality produced from both bleaching sequences was better than pulp bleached by the chlorination, alkaline extraction, and hypochlorite (CEH) sequence. The wastewater was discharged only from the Q or D stage, and the chemical oxygen demand (COD) of Q or D stage was about 650 mg/L or 1100 mg/L, respectively. It was easy to alternate between these two bleaching sequences, and the bleached pulp quality from these sequences was stable.

Made available in DSpace on 2019-10-04T12:32:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-01. Added 1 bitstream(s) on 2019-10-09T18:33:40Z : No. of bitstreams: 1 S0100-67622018000500204.pdf: 1025651 bytes, checksum: de6bfebd9d607bbc11792c07f54d471f (MD5) The kraft pulp of Eucalyptus spp. is relatively easy to be bleached. Therefore, studies have been carried out to reduce the number of stages of bleaching in the plant and minimize process costs. The present work aimed to evaluate the use of two short bleaching sequences in the physico-mechanical properties of cellulosic pulp as well as to compare these values to the ones obtained by usual bleaching sequences. The four bleaching sequences were ECF (elemental chlorine free), D-0(E+P)D1P, A(HT)D(0)(E+P)D1P, and A(HT)DP and A(HT)D (PO). For each bleaching sequence the brightness, brightness reversion and total cost of reagents were evaluated. Physical and mechanical analyses were performed according to the methodologies of the Technical Association of the Pulp and Paper Industry (TAPPI, 2002). The A(HT)D (PO) sequence showed higher brightness, less brightness reversion, lower total cost and better smoothness compared to the reference sequences. However, it had a lower tear index and a lower compression index. The A(HT)DP sequence did not reach target brightness, however, it presented brightness reversion and lower total cost than the reference sequences. The A(HT)DP sequences showed high compression and smoothness, but presented a low compression index. Univ Estadual Paulista, Programa Posgrad Engn Mecan, Guaratingueta, SP, Brazil Univ Estadual Paulista, Dept Engn Ind Madeireira, Itapeva, SP, Brazil Univ Estadual Paulista, Programa Posgrad Engn Mecan, Guaratingueta, SP, Brazil Univ Estadual Paulista, Dept Engn Ind Madeireira, Itapeva, SP, Brazil

Environmental degradation by industrial and other developmental activities is alarming for imperative environmental management by process advancements of production. Pulp and paper mills are now focusing on using nonwood-based raw materials to protect forest resources. In present study, rice straw was utilized for pulp production as it is easily and abundantly available as well as rich in carbohydrates (cellulose and hemicelluloses). Soda-anthraquinone method was used for pulp production as it is widely accepted for agro residues. Bleaching process during paper production is the chief source of wastewater generation. The chlorophenolic compounds generated during bleaching are highly toxic, mutagenic, and bioaccumulative in nature. The objectives of study were to use oxygen delignification (ODL) stage prior to elemental chlorine-free (ECF) bleaching to reduce wastewater load and to study its impact on bleached pulp characteristics. ODL stage prior to ECF bleaching improved the optical properties of pulp in comparison to only ECF bleaching. When ODL stage was incorporated prior to bleaching, the tensile index and folding endurance of the pulp were found to be 56.6 ± 1.5 Nm/g and 140, respectively, very high in comparison to ECF alone. A potential reduction of 51, 57, 43, and 53% in BOD3, COD, color, and AOX, respectively was observed on adding the ODL stage compared to ECF only. Generation of chlorophenolic compounds was reduced significantly. Incorporation of ODL stage prior to bleaching was found to be highly promising for reducing the toxicity of bleaching effluents and may lead to better management of nearby water resources.

Self-assembly is a technique of preparing functional materials based on targeted intermolecular interactions involving different macromolecules. In this work, hardwood xylan was disassembled from wood and birch bleached kraft pulp using pressurized hot water extraction (HWX) and cold alkali extraction (CAX), respectively. The extracted biopolymers were characterized using gas chromatography (GC), size exclusion chromatography (SEC) and Fourier transform infrared spectroscopy (FTIR), and subsequently added into an oxygen delignification reactor containing pine kraft pulp. The assembly of xylan-pulp fiber was characterized using advanced time-of-flight secondary ion mass spectrometry (ToF-SIMS) and imaging. The xylan-pine pulp assembly was not significantly removed during the whole elemental chlorine free bleaching sequence or during low consistency refining. Modified fibers had superior mechanical properties compared to the reference pulp. Our concept can be easily applied in the pulp and paper industry, and it opens new possibilities for the utilization of fully bio-based fibers in new materials.

BACKGROUND Electrochemical advanced oxidation processes (EAOPs), particularly those based on either cathodic electrogeneration of H2O2 or anodic oxidation (AO) via •OH, have become attractive technological options for the complete detoxification of wastewaters. Their integration with separation pre-treatment such as ultrafiltration (UF), nanofiltration (NF) or reverse osmosis (RO) may be a plausible way to reduce processing time and costs. RESULTS Raw effluents from the acid and alkaline elemental chlorine free bleaching stages of a hardwood-based kraft pulp mill, as well as their UF, NF and RO permeates, have been characterized and then treated by AO-H2O2 in a tank reactor with an air-diffusion cathode, which allowed efficient reduction of O2, and a DSA-RuO2 or BDD anode at constant cell voltage (2–12 V). Due to the complexity of the matrix, a larger H2O2 accumulation in the acid effluents was observed. DSA favoured the accumulation of ions, whereas BDD allowed their further transformation into owing to the larger oxidizing power of its physisorbed •OH. The contribution of this species, along with H2O2 and active chlorine, accounted for the significant TOC abatement reached in the different individual and coupled treatments. CONCLUSIONS AO-H2O2 and UF/AO-H2O2 yielded similar mineralization levels (65–68%) for acid effluents, but lower energy consumption (EC) resulted in the latter process due to the lower conductivity of the permeates. NF/AO-H2O2 coupling yielded the largest mineralization of alkaline effluents (96% instead of 75% obtained by AO-H2O2) with low EC. © 2014 Society of Chemical Industry

The pulp and paper industries are attempting to bring changes to the bleaching process to minimize the use of chlorine to satisfy regulatory and market demands. Xylanases offer a cost-effective way for mills to realize a variety of benefits in bleaching. One main benefit is reducing Adsorbable Organic Halides (AOX) discharge. This is achieved primarily by decreasing chlorine gas usage. Other benefits include eliminating chlorine gas usage in mills with high chlorine dioxide substitution levels and increasing the brightness ceiling (particularly for mills contemplating Elemental Chlorine Free (ECF) and Totally Chlorine Free (TCF) bleaching sequences and in mills using large amounts of peroxide or chlorine dioxide). These benefits are achieved in the long term when the enzymes are properly selected and integrated into the process. This review summarizes the application of xylanases in the bleaching of pulp, with emphasis on the mechanism and effects of xylanase treatment on pulp and paper and the factors affecting the bleaching process and its efficiency. Brightness gains of up to 1.4 to 2.1 units have been achieved with xylanase treatment with the reduction of chlorine consumption by 15.0%. Xylanase treatment can lower the AOX amount in filtrate by 25.0% as compared to references. The Chemical Oxygen Demand (COD) can be reduced by 85%.

Kinetics study of oxidation of 1-(3,4-Dimethoxyphenyl)ethanol (MVA), a lignin model compounds, with chlorine dioxide under simulated bleaching conditions were investigated. The UV–vis spectrophotometer was employed to characterize the reaction products of chlorine dioxide and 1-(3,4-Dimethoxyphenyl)ethanol. A possible reaction mechanism was proposed. The results showed the chlorination and oxidizing reaction of 1-(3,4-Dimethoxyphenyl)ethanol coexisted. The hypochlorous acid was the main reason to form adsorbable organic halides (AOX). An overall second-order rate equation was also established from UV–vis spectra results. It was shown as: −d[ClO2]/dt = k′[MVA][ClO2], where k′ refers to observed second-order rate constants. The results showed the kinetics model correlated well with the experimental data, so the degree of 1-(3,4-Dimethoxyphenyl)ethanol oxidized by chlorine dioxide can be quantitative evaluated based on this model. AOX formation characteristic and practical implications of this work were investigated based on the kinetics and mechanism, which might bring a new door open for resolving the major problems of environmental pollution in elemental chlorine free (ECF) bleaching of pulp.

Aims: To evaluate the pulp and papermaking characteristics of Thaumatococcus daniellii stalks using soda and soda-ethanol pulping methods. Study Design: A completely randomized design was used. Place and Duration of Study: Department of Chemical Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, Canada, between June 2010 and July 2011. Methodology: The stalks of T. daniellii were pulped with both sodium hydroxide (NaOH) and soda-ethanol (NaOH-C2H5OH) liquors in a 10-litre electrically heated stainless steel digester. Cooking temperature was varied at 140, 150 and 160 C while the concentration of the cooking liquor was kept constant at 12% NaOH and 12:40% by volume of NaOHC2H5OH and cooked for 60 minutes. The bleachability of the pulp was assessed using DEDD elemental chlorine free bleaching sequence. The bleached pulp was beaten in a PFI mill at revolution of 0, 1600 and 3200 followed by formation of handsheet in a Original Research Article British Journal of Applied Science & Technology, 4(15): 2181-2193, 2014 2182 standard sheet former. Lastly, the elrepho brightness, bulk, apparent sheet density, tear index, burst index, tensile index and the breaking length of the handsheets produced from the two pulp types were evaluated using standard tappi methods. Results: The temperature and pulping method had marked effects on the yield, kappa number and brightness of the pulps. Also, beating revolutions had significant effect on the physical and strength properties of the handsheets produced from both pulps (P = 0.05). The yield and bleaching properties of soda-ethanol pulps are superior to those of soda pulps. Handsheets produced from soda-ethanol pulps also had significantly higher strength, particularly in unbeaten and when beaten at 1600 revolution (P = 0.05). Beyond 1600 revolution, the tear index, tensile index and breaking length of soda-ethanol handsheet were not significantly higher than those from soda pulp (P ≥ 0.05). Conclusion: Handsheets produced from T. daniellii stalks had physical and strength characteristics that are comparable to those from notable non-wood fibre source. It is therefore expected that the stalk can play a big role in complementing wood fibres in pulp and papermaking.

Increased ethoxyresorufin-O-deethylase (EROD) activity is a sensitive biomarker of exposure to the chemicals which activate the aryl hydrocarbon receptor (AhR) and induce the cytochrome P450 system, such as many polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs). Pulp bleaching was one of the main sources of PCDDs and PCDFs until elemental chlorine free (ECF) and total chlorine free bleaching processes since 1990s have remarkably decreased but not completely eliminate discharges of these chemicals. In addition, historically contaminated sediments may act as a source of these persistent contaminants. In this study, the contamination history and recovery of a watercourse heavily loaded by the chemical wood industry were studied by analyzing PCDDs, PCDFs and PCBs from vertical sediment samples and by measuring hepatic EROD activity from rainbow trout intraperitoneally dosed with the sediment extracts. No PCDDs or PCDFs were found above the chromatographic limit of detection from the study area and only small amounts of PCB congeners 101, 138, 153, and 180 were present. No increased EROD activity was observed in fish indicating the absence of any AhR-activating compounds in the surface sediment, to about 15 cm depth, representing about the last 20 years when kraft pulping and ECF bleaching with activated wastewater treatment have been used. It can be concluded that nowadays organochlorines and other AhR-ligands do not harm the previously heavily polluted watercourse.

The Chilean abalone or "loco" (Concholepas concholepas, Bruguière 1789) represent the most economically important marine recourse exploited from inner inshore Management and Exploitation Areas for Benthic Resources along the Chilean coast. In this study, newly-hatched larvae of C. concholepas were investigated as a potential model species for marine ecotoxicological studies. The study developed a behavioral standard protocol for assessing the impact that kraft pulp mill effluents after secondary treatment have on C. concholepas larvae. Under controlled laboratory conditions, newly-hatched larvae were exposed to a series of different concentrations of kraft pulp mill effluents with secondary treatment (Pinus spp. and Eucalyptus spp.), potassium dichromate as standard reference toxicant and effluent-free control conditions. Regardless of the type of effluent the results indicated that diluted kraft pulp effluent with secondary treatment had reduced effect on larval survival. Low larval survivals were only recorded when they were exposed to high concentrations of the reference toxicant. This suggests that C. concholepas larval bioassay is a simple method for monitoring the effects of kraft pulp mill effluents with secondary treatment discharged into the sea. The results indicated that dilution of ca. 1% of the effluent with an elemental chlorine free (ECF) secondary treatment is appropriate for achieving low larval mortalities, such as those obtained under control conditions with filtered seawater, and to minimize their impact on early ontogenetic stages of marine invertebrates such as newly-hatched larvae of C. concholepas. The methodological aspects of toxicological testing and behavioral responses described here with newly-hatched larvae of C. concholepas can be used to evaluate in the future the potential effects of other stressful conditions as other pollutants or changes in seawater pH associated with ocean acidification.

ZDED and DEDD sequences were applied on an oxygen-delignified eucalyptus (mixture of E. grandis and E. saligna) kraft pulp from Brazil. When ZDED and DEDD were compared, the displacement ratio calculated as the quantity of pure chlorine dioxide replaced by 1 kg ozone was found between 2.5 and 3.5 kg, as compared to 1.7 kg in theory—indicating that less wasting reactions occur in the ZDED sequence. The cellulose viscosity decreased substantially with the increase in the ozone charge (down to 50% at 0.8% ozone). Other typical characteristics of the ZDED pulps were easier beating, lower water retention value, higher proportion of kinked fibers, and lower wet zerospan breaking length (seen only at 0.8% ozone charge), as compared to DEDD. The viscosity loss due to the introduction of ozone in an elemental chlorine free sequence did not translate into a similar loss in strength. A comparison with the depolymerizing effect of cellulase suggests that the determining factor is not the extent of the drop in viscosity but rather the heterogeneity of the attack along the fibers. It is concluded that ozone oxidation of cellulose in the fibers would be rather homogeneous. Moreover, the appearance of more curls and kinks would not be necessarily related to the viscosity loss. For example, a (2,2,6,6-tetramethylpiperidin- 1-yl)oxidanyl (TEMPO) treated DEDD pulp, enriched in carboxyl groups, had more straight fibers than the original DEDD pulp, despite its lower viscosity. The presence of ionic groups would be a more important factor; the lower content in carboxyl groups in the ZDED pulps, compared to the DEDD pulps, could promote the easier formation of curl and kinks during the ZDED sequence.

This investigation evaluates how higher reaction temperatures or oxidant reinforcement of caustic extraction affects chlorine dioxide consumption during elemental chlorine-free bleaching of North American hardwood pulps. Bleaching data from the published literature were used to develop statistical response surface models for chlorine dioxide delignification and brightening sequences for a variety of hardwood pulps. The effects of higher (EO) temperature and of peroxide reinforcement were estimated from observations reported in the literature. The addition of peroxide to an (EO) stage roughly displaces 0.6 to 1.2 kg chlorine dioxide per kilogram peroxide used in elemental chlorine-free (ECF) bleach sequences. Increasing the (EO) temperature by Δ20°C (e.g., 70°C to 90°C) lowers the overall chlorine dioxide demand by 0.4 to 1.5 kg. Unlike what is observed for ECF softwood bleaching, the presented findings suggest that hot oxidant-reinforced extraction stages result in somewhat higher bleaching costs when compared to milder alkaline extraction stages for hardwoods. The substitution of an (EOP) in place of (EO) resulted in small changes to the overall bleaching cost. The models employed in this study did not take into account pulp bleaching shrinkage (yield loss), to simplify the calculations.

The aim of this study was to further evaluate the viability of the integrated pulp mill biorefinery concept. On one side the properties of hot-water pre-extractions were studied, in order to determine the effect of extraction on soda pulping and bleachability. On the other side, the performance of two dry-strength agents on the paper properties obtained from extracted and un-extracted (control) samples were investigated. It was found that hemicelluloses removal of the depithed bagasse chips was 24.6% at 140 °C for 10 min with a solid to liquor ratio (S:L) of 1:8 (w/w), and that mass removal increased with extraction time and temperature. The hemicelluloses removal reached 65.5% at 170 °C for 30 min. The residual extracted bagasse were subjected to soda pulping at 160 °C for 1 h with 11, 14 and 17% active alkali charge and a S:L of 1:5 (w/w). Conventional elemental chlorine free bleaching ( D 0 ED 1 ) sequence was also used to compare the results with the un-extracted ones. Compared with the control sample, the overall pulp yield for extracted bagasse increased considerably while Kappa number and rejects decreased moderately. In addition, yield and Kappa number of the pulps improved with increasing alkali charge from 11% to 17%. After pre-extraction, better brightness compared with the control pulp was also shown. However, hot-water extraction was found to negatively impact some pulp properties including decreases in burst and tensile indices while addition of chitosan and cationic starch could improve the strength properties. Overall, papers treated with chitosan gave superior mechanical properties compared to the papers treated with cationic starch.

Elemental Chlorine Free (ECF) bleaching sequence of O1/O2D0EOPD1D2 was adopted to bleach the pro-hydrolyzed Larix kraft pulp, where O1/O2 was two-stage oxygen delignification without interstage treatment, D was chlorine dioxide bleaching, EOP was pressurized alkaline extraction strengthened by hydrogen peroxide. Keeping bleaching temperature and time unchanged, sodium hydroxide charge(NaOH) in O1 stage, chlorine dioxide(ClO2) charge in D0 stage and D2 stage were studied, pulp properties such as brightness, kappa number, alpha-cellulose, pentosan and polymerization degree were measured and compared to establish optimal bleaching conditions. Results show that the optimal charge of NaOH in O1 stage is 2.5%, ClO2 in D0 and D2 stage are 2.5%, 0.6%, and the pulp gained at the optimal bleaching conditions has the properties of 93.9% of alpha-cellulose, 2.60% of pentosan, 375.5 ml/g of viscosity and 86.6%ISO of brightness.

Pulp and paper industry is one of the major contributors to environmental pollution due to its toxic and carcinogenic discharges during its various processes e.g., chlorinated bleaching of the pulp. Use of alternative bleaching chemicals e.g., enzyme and/or elemental chlorine free (ECF) or total chlorine free (TCF) agents are the best option to reduce the load of carcinogenic chlorinated compounds on our environment. Present study was carried out to highlight the application of enzyme during bleaching of wheat straw anthraquinon (AQ)-soda pulp to considerably reduce the toxic load on the environment. Wheat straw AQ-soda pulp was treated with acid (A) to reduce its metal contents followed by oxygen (O) delignification. Delignified pulp was then subjected to enzymatic (X) treatment with xylanase prior to bleaching to increase the effectiveness of successive bleaching with hydrogen peroxide (P). Handsheets were prepared from the treated pulp after each experimental trial to study its various optical, physical and chemical properties. Brightness of bleached pulp was improved up to ISO 73% with AOXP1P2 bleaching sequence. The improved brightness up to ISO 76% was achieved when alkali extraction stage was incorporated before bleaching with hydrogen peroxide (AOXEP1P2). TDS, COD and BOD5 of effluent samples during different experimental stages was monitored and compared with NEQS. It was evident from the results that enzymatic treatment not only helped to reduce the effluent load but also reduced the consumption of bleaching chemicals to achieve good brightness values.

Pulp and paper mills are indispensable for any nation as far as the growth of the nation is concerned. Due to fast growth in population, urbanization and industrialization, the demand and consumption of paper has increased tremendously. These put high load on our natural resources and force the industry to look for alternative raw material. Rice straw is a lignocellulosic material abundantly available in wood short countries like China, India, Bangladesh, etc. and can be used as raw material for this industry. Open burning of rice straw releases noxious green house gases to the air and poses serious threats to global air chemistry and human health. So, it is a dual benefit option (for farmers and industries) to use rice straw as a raw material in pulp and paper industry. Organosolv pulping using acids are the prominent choices of researchers to convert this residue into valuable pulp but in developed countries only. Developing world favours the soda and soda-AQ processes as these are economical. As a virtue of less lignin content in comparison to wood, rice straw requires less harsh conditions for cooking and can be easily pulped. Bleaching is a crucial step of paper making but also responsible for causing water pollution. Many studies revealed that during the process more than 500 chlorinated compounds are released that are highly toxic, bioaccumulative and carcinogenic in nature. Most of the industries over the globe switch on to the elemental chlorine free short sequence bleaching methods using chlorine dioxide, hypochlorite and hydrogen peroxide. This paper presented the effective need of ecofriendly, economically reliable pulping and bleaching sequences in case of rice straw to eliminate the problems of chlorinated compounds in wastewater of paper mills. Such approach of using waste as a raw material with its environmentally safe processing for making paper can prove to be valuable towards sustainable growth.

Few data exist on the possible effects of pulp and paper effluent discharge on native fish populations in the Southern Hemisphere, relative to the research done in the Northern Hemisphere. The present research examined two native fish species (Trichomycterus areolatus and Percilia gillissi) for effects at both the molecular and individual level due to the discharge of effluent from a tertiary treated elemental chlorine-free pulp mill into a fluvial system in Central Chile over three seasons (February 2007, October 2007, January 2008). Different responses were observed between species and between sexes. There was an increase in the production of gonadal 17β-estradiol in the females of both species but a drop in 11-ketotestosterone production in P. gillissi males. Female gonadal size was increased, especially during the summer period, with corresponding increases the frequency of advanced oocyte development, and in the oocyte diameter in both species. Hepatic ethoxyresorufin-O-deethylase (EROD) activity was elevated for both species downstream of the discharge point, although overall it was higher in P. gillissi than T. areolatus. Decreases in the frequency of smaller-sized fish for both species, as well as a drop in the size of the adults downstream of the discharge point, were observed. The present study is the first evidence of endocrine disruption in native freshwater fish associated with modern pulp mills in South America. This study establishes possible links in the reproductive alterations observed at the subindividual and individual levels that could explain the changes observed at the population level. Environ. Toxicol. Chem. 2011; 30:1793–1809. © 2011 SETAC

A solar Fenton process was applied as post-treatment to selectively eliminate organic pollutants and toxicants in bleaching effluents of kraft pulp mills. Experiments were conducted to study the effect of system parameters (pH, initial concentration of H2O2, molar ratio of Fe2+/H2O2 and solar-UV irradiance) on the removals of chemical oxygen demand and colour. The results showed 92.8% of COD and 99.6% of colour were removed at pH 3.5, H2O2 30 mM/ L, Fe2+/H2O2 1:100, solar-UV irradiance 11070 mW/m2, reaction time 120 min. The first-order kinetic model was used to study the dependence of the reaction rate on solar-UV irradiance: a linear relationship was shown to exist between reaction rate constants and solar-UV irradiance. The results of gas chromatography mass spectrometry analysis showed that the toxicity of the bleaching effluents was mainly derived from the presence of mononuclear aromatics, polycyclic aromatic hydrocarbons and organochlorides, which were all degraded into harmless organic acids under the attack of hydroxyl radicals generated from the solar Fenton reaction.

As one of the main emission sources of PCDD/Fs, the pulp and paper industry has always been public concerns. In China, the consumption of non-wood fiber as raw material of pulp accounts for a relatively larger proportion in the total productivity. Here, the unintentionally produced PCDD/Fs emissions of five Chinese non-wood pulp and paper mills were investigated. The results showed that the increment of PCDD/Fs after bleaching with chlorine was about 1.71-28.19 times in pulp and 3.96-28.82 times in wastewater based on the existing technologies. In order to reduce the unintentional production of PCDD/Fs, the BAT/BEP transformation program was proposed as cleaner production initiatives featured by less or free use of chlorine in bleaching process, and evaluated by reduction effects and costs. The study showed the application of Elemental Chlorine Free (ECF) sequences in bleaching process with improving technologies in other production stages would effectively decrease the generation of PCDD/Fs, other pollutant load as well as the water consumptions.