EP0383999A2 - Procedure for the bleaching of pulp - Google Patents

Procedure for the bleaching of pulp Download PDF

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Publication number
EP0383999A2
EP0383999A2 EP89117235A EP89117235A EP0383999A2 EP 0383999 A2 EP0383999 A2 EP 0383999A2 EP 89117235 A EP89117235 A EP 89117235A EP 89117235 A EP89117235 A EP 89117235A EP 0383999 A2 EP0383999 A2 EP 0383999A2
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EP
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Prior art keywords
pulp
bleaching
chlorine
enzyme
treatment
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Granted
Application number
EP89117235A
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German (de)
French (fr)
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EP0383999A3 (en
EP0383999B1 (en
Inventor
Marja Vaheri
Veikko Jokela
Kari Miikki
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Stora Enso Oyj
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Enso Gutzeit Oy
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Priority to AT89117235T priority Critical patent/ATE103351T1/en
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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
    • D21C9/10—Bleaching ; Apparatus therefor
    • D21C9/1057—Multistage, with compounds cited in more than one sub-group D21C9/10, D21C9/12, D21C9/16
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
    • D21C5/005—Treatment of cellulose-containing material with microorganisms or enzymes
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
    • D21C9/10—Bleaching ; Apparatus therefor
    • D21C9/12—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds
    • D21C9/14—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds with ClO2 or chlorites

Definitions

  • the present invention relates to a procedure for the bleach­ing of pulp, in which procedure an oxidating bleaching chemical containing chlorine is used.
  • Especially pulp obtained from a sulphate pulping process is of brown colour, which is mainly due to the lignin remaining in the pulp.
  • Lignin is removed from the pulp by bleaching, which is a process consisting of several stages. During this process, the pulp is treated alternately with oxidizing, lignin-degrading chemicals and chemicals dissolving the de­gradation products.
  • Oxidizing agents commonly used are oxy­gen and chlorine-containing chemicals such as pure chlorine gas, chlorine dioxide and sodium and calcium hypochlorites, whereas alkali solutions are used for eliminating the degradation products.
  • the spent bleach liquors causing the worst environmental pollution load are produced during the washing following the first chlorination and the first alkali treatment in the bleaching process.
  • various methods have been employed, e.g. the so-called extended digestion, the use of chlorine dioxide as an oxi­dating bleaching chemical, oxygen bleaching and biological purification of the spent bleach liquor.
  • the re­sults achieved by these methods are not completely satis­factory.
  • the amounts of chlorophenols and other toxic chlorine compounds in the spent bleach liquor have been significantly reduced by employing chlorine dioxide and oxygen bleaching, it has not been possible to achieve a suf­ficient reduction in the chemical oxygen demand values of the effluents. Therefore, the methods referred to have re­quired the employment of efficient biological purification.
  • the object of the present invention is to achieve a solution that enables the toxic content and chemical oxygen demand of the spent bleach liquor to be reduced so as to reduce the need for purification of the liquor.
  • the invention is char­acterized in that a chemical with a chlorine dioxide content of at least 50 % is used in the oxidation stage, that the pulp is subjected to enzyme treatment in conjunction with or before the oxidation, and that after the oxidation and enzyme treatment the pulp is treated with an alkali.
  • the pulp is subjected to enzyme treatment and washing before the first oxidation stage.
  • the enzyme breaks down hemicellulose and/or lignin contained in the pulp and renders the pulp more spongy, thus enhancing the effect of the chemicals in subsequent oxidation and alkali treatment stages.
  • the degradation products are removed and can be burned so that they will not contribute to the effluent emissions at all.
  • the bleaching of pulp by the procedure of the invention can be performed in the con­ventional manner by employing alternate oxidation and alkali treatment phases and washing the pulp after each of these phases to remove the bleaching chemicals and degradation products.
  • the enzyme treatment as taught by the invention is preferivelyably carried out in a temperature range of 10-90 °C, the most suitable range being 40-75 °C, with pH values in the range 3.0-10.0, preferably 4.0-9.0.
  • the enzyme used can be a hemicellulase, cellulase, pectinase, esterase or a mixture of these.
  • the invention also concerns the use of an enzyme for re­ducing the chlorine content of the spent bleach liquor pro­duced in the bleaching of pulp when an oxidating bleaching chemical containing at least 50 % of chlorine dioxide is used.
  • the enzyme is preferably hemicellulase, cellulase, pectinase, esterase or a mixture of these. The enzyme is used essentially in the manner explained in the above description of the bleaching procedure.
  • a diluted enzyme mixture (streptomyces hemicellulase) was added to 220 g of dry matter obtained from birch sulphate pulp (with a dry matter content of 30%) so that a mixture with a consistency of 10% and xylanase activity of 5 U/g of pulp dry matter was obtained.
  • the temperature in the enzyme treatment was 55 °C, the duration of treatment 2 h and pH 8.0.
  • the pulp was subjected to an oxi­dating bleaching treatment using a mixture containing 90 % chlorine dioxide and 10 % chlorine gas, in a dosage equal to 1.4 x post-enzyme-treatment kappa number of the pulp. Treat­ment temperature was 55 °C and duration of treatment 45 min. After the oxidation phase the pulp was washed in a Büchner funnel with a 20-fold amount of water.
  • the pulp was subjected to an alkali treatment using a 5 % sodium hydroxide solution in a dosage of 0.8 x kappa. Consistency of the mixture was 10 %, treatment temperature 60 °C and duration of treatment 90 min. After the alkali treatment the pulp was washed in the same way as after the oxidation phase.
  • the pulp was treated with an enzyme and bleached as described above (exp. 3). In addition, the pulp was washed after the enzyme treatment, before the first oxidating treatment, with a mixture of chlorine dioxide and chlorine gas.
  • the present invention comprises a procedure employing the principle of this experiment.
  • Bleaching AOX COD kg/t of chemical pulp
  • Experiment 1 reference
  • Experiment 2 reference
  • Enzyme treatment Bleaching with mixture 0.6 40 90 % C102 + 10 % Cl2
  • Experiment 4 Enzyme treatment, washing Bleaching with mixture 0.6 40 90 % C102 + 10 % Cl2
  • a diluted enzyme mixture (streptomyces hemicellulase) was added to 220 g of dry matter obtained from pine sulphate pulp (with a dry matter content of 30%) so that a mixture with a consistency of 10% and a xylanase activity of 5 U/g of pulp dry matter was obtained.
  • the temperature in the enzyme treatment was 55 °C, the duration of treatment 2 h and pH 8.5.
  • the pulp was subjected to an oxidating bleaching treatment using a mixture which contained 80 % chlorine dioxide and 20 % chlorine gas.
  • the dosage of the mixture was 1.4 x kappa number of the pulp after enzyme treatment.
  • Treatment temperature was 55 °C and duration of treatment 45 min.
  • the pulp was washed in a Büchner funnel with a 20-fold amount of water.
  • the pulp was subjected to an alkali treatment using a 5 % sodium hydroxide solution in a dosage of 0.9 x kappa. Consistency of the mixture was 2 %, treatment temperature 45-55 °C and duration of treatment 90 min. After the alkali treatment the pulp was washed in the same way as after the oxidation phase.
  • the pulp was treated with an enzyme as de­scribed above.
  • the bleaching chemical used in the oxidation phases was pure chlorine gas, in a dosage of 2 x kappa. In other respects, the experiment was analogous to that de­scribed above (exp. 4.)

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Chemical & Material Sciences (AREA)
  • Biochemistry (AREA)
  • Microbiology (AREA)
  • Paper (AREA)
  • Polysaccharides And Polysaccharide Derivatives (AREA)
  • Noodles (AREA)
  • Cereal-Derived Products (AREA)
  • Table Devices Or Equipment (AREA)
  • Silver Salt Photography Or Processing Solution Therefor (AREA)

Abstract

The invention concerns a procedure for the bleaching of pulp using an oxidating bleaching chemical containing chlorine. The essential features of the invention are that the chemi­cal used in the oxidation stage has a chlorine dioxide con­tent of at least 50 %, that the pulp is subjected to enzyme treatment either in conjunction with or before the oxida­tion, and that, after the oxidation and enzyme treatment, the pulp is treated with an alkali. The use of enzymes re­duces the amount of chlorophenols and other forms of organi­cally bound chlorine in the spent bleach liquor, simulta­neously lowering its chemical oxygen demand.

Description

  • The present invention relates to a procedure for the bleach­ing of pulp, in which procedure an oxidating bleaching chemical containing chlorine is used.
  • Especially pulp obtained from a sulphate pulping process is of brown colour, which is mainly due to the lignin remaining in the pulp. Lignin is removed from the pulp by bleaching, which is a process consisting of several stages. During this process, the pulp is treated alternately with oxidizing, lignin-degrading chemicals and chemicals dissolving the de­gradation products. Oxidizing agents commonly used are oxy­gen and chlorine-containing chemicals such as pure chlorine gas, chlorine dioxide and sodium and calcium hypochlorites, whereas alkali solutions are used for eliminating the degradation products.
  • In the reactions occurring in bleaching using chlorine-con­taining chemicals, lignin is converted into organic chlorine compounds, which are dissolved in the spent bleach liquor. Spent bleach liquors are a problem in regard of environment­al protection because of the toxic nature of the chlorophe­nols and other possible organic chlorine compounds contained in the liquids. Besides, the chemical oxygen demand in spent bleach liquors reaches detrimental levels. As the measures aimed at reducing the environmental pollution load resulting from sulphate pulp production have so far been concentrated on other parts of the process except bleaching, the relative significance of bleaching as a polluting factor has been increasing.
  • The spent bleach liquors causing the worst environmental pollution load are produced during the washing following the first chlorination and the first alkali treatment in the bleaching process. To reduce the emissions of effluents, various methods have been employed, e.g. the so-called extended digestion, the use of chlorine dioxide as an oxi­dating bleaching chemical, oxygen bleaching and biological purification of the spent bleach liquor. However, the re­sults achieved by these methods are not completely satis­factory. Although the amounts of chlorophenols and other toxic chlorine compounds in the spent bleach liquor have been significantly reduced by employing chlorine dioxide and oxygen bleaching, it has not been possible to achieve a suf­ficient reduction in the chemical oxygen demand values of the effluents. Therefore, the methods referred to have re­quired the employment of efficient biological purification.
  • The object of the present invention is to achieve a solution that enables the toxic content and chemical oxygen demand of the spent bleach liquor to be reduced so as to reduce the need for purification of the liquor. The invention is char­acterized in that a chemical with a chlorine dioxide content of at least 50 % is used in the oxidation stage, that the pulp is subjected to enzyme treatment in conjunction with or before the oxidation, and that after the oxidation and enzyme treatment the pulp is treated with an alkali.
  • It has been observed in earlier investigations that by using enzymes it is possible to separate lignin and/or hemicellu­lose from cellulose and thus give the pulp a more spongy quality. This justifies the assumption that if the pulp ob­tained from the digestion process is first subjected to en­zyme treatment, it is possible to reduce the amount of chem­icals used in the next bleaching phase. According to the in­vention, it has now been observed that enzyme treatment sub­stantially reduces the amount of organic chlorine compounds in the spent bleach liquor while at the same time reducing its chemical oxygen demand, especially when at least 50 %, preferably at least 70 %, of the bleaching chemical used in the oxidation stage consists of chlorine dioxide. If pure chlorine gas is used, enzyme treatment has a substantially weaker effect on the quality of the spent bleach liquor.
  • According to the invention, the pulp is subjected to enzyme treatment and washing before the first oxidation stage. The enzyme breaks down hemicellulose and/or lignin contained in the pulp and renders the pulp more spongy, thus enhancing the effect of the chemicals in subsequent oxidation and alkali treatment stages. By washing the pulp after the enzyme treatment, the degradation products are removed and can be burned so that they will not contribute to the effluent emissions at all.
  • Except for the enzyme treatment, the bleaching of pulp by the procedure of the invention can be performed in the con­ventional manner by employing alternate oxidation and alkali treatment phases and washing the pulp after each of these phases to remove the bleaching chemicals and degradation products.
  • The enzyme treatment as taught by the invention is prefer­ably carried out in a temperature range of 10-90 °C, the most suitable range being 40-75 °C, with pH values in the range 3.0-10.0, preferably 4.0-9.0. The enzyme used can be a hemicellulase, cellulase, pectinase, esterase or a mixture of these.
  • The invention also concerns the use of an enzyme for re­ducing the chlorine content of the spent bleach liquor pro­duced in the bleaching of pulp when an oxidating bleaching chemical containing at least 50 % of chlorine dioxide is used. The enzyme is preferably hemicellulase, cellulase, pectinase, esterase or a mixture of these. The enzyme is used essentially in the manner explained in the above description of the bleaching procedure.
  • In the following, the invention is described in greater detail by the aid of examples of embodiments based on laboratory experiments.
    • Example 1
  • A diluted enzyme mixture (streptomyces hemicellulase) was added to 220 g of dry matter obtained from birch sulphate pulp (with a dry matter content of 30%) so that a mixture with a consistency of 10% and xylanase activity of 5 U/g of pulp dry matter was obtained. The temperature in the enzyme treatment was 55 °C, the duration of treatment 2 h and pH 8.0.
  • After the enzyme treatment the pulp was subjected to an oxi­dating bleaching treatment using a mixture containing 90 % chlorine dioxide and 10 % chlorine gas, in a dosage equal to 1.4 x post-enzyme-treatment kappa number of the pulp. Treat­ment temperature was 55 °C and duration of treatment 45 min. After the oxidation phase the pulp was washed in a Büchner funnel with a 20-fold amount of water.
  • Next, the pulp was subjected to an alkali treatment using a 5 % sodium hydroxide solution in a dosage of 0.8 x kappa. Consistency of the mixture was 10 %, treatment temperature 60 °C and duration of treatment 90 min. After the alkali treatment the pulp was washed in the same way as after the oxidation phase.
  • After this, the bleaching was continued by repeating the oxidation and alkali phases and then once more the oxidation phase and washing the pulp between these phases as described above. For the combined wash waters, the amount of organic­ally bound chlorine (AOX) and the chemical oxygen demand (COD) were determined, and these are presented in Table 1 (experiment 3) below.
  • In addition to the above-described experiment (exp. 3) il­lustrating the invention, two reference experiments (experi­ments 1 and 2) and an additional experiment (exp. 4) were carried out, and the AOX and COD values of the combined wash waters obtained from different stages of the experiments are also presented in Table 1. The experiments were performed as follows:
    • Experiment 2 (reference):
  • No enzyme treatment was employed. The dosage of bleaching chemicals in different stages of treatment during the bleaching was 2 x kappa, the commonly used dosage. In other respects, the experiment was analogous to that described above (exp. 3).
    • Experiment 1 (reference):
  • No enzyme treatment was employed. The bleaching chemical used in the oxidation stages was pure chlorine gas, in a dosage of 2 x kappa. In other respects, the experiment was analogous to that described above (exp. 3.)
    • Experiment 4:
  • The pulp was treated with an enzyme and bleached as described above (exp. 3). In addition, the pulp was washed after the enzyme treatment, before the first oxidating treatment, with a mixture of chlorine dioxide and chlorine gas. The present invention comprises a procedure employing the principle of this experiment. TABLE 1
    Bleaching AOX COD
    (kg/t of chemical pulp)
    Experiment 1 (reference)
    No enzyme treatment 2.6 58.1
    Cl₂ bleaching
    Experiment 2 (reference)
    No enzyme treatment
    Bleaching with mixture 1.0 55.0
    90 % C10₂ + 10 % Cl₂
    Experiment 3
    Enzyme treatment
    Bleaching with mixture 0.6 40
    90 % C10₂ + 10 % Cl₂
    Experiment 4
    Enzyme treatment, washing
    Bleaching with mixture 0.6 40
    90 % C10₂ + 10 % Cl₂
  • The results indicate that, in comparison to corresponding bleaching without enzyme treatment, enzyme treatment com­bined with chlorine dioxide bleaching as provided by the in­vention substantially reduces the pollution load caused by the spent bleach liquors as measured in terms of AOX and COD values. Compared to the commonly used chlorine bleaching, the improvement achieved is even more distinct. Furthermore, it is worth noting that in the experiments representing the invention, the same degree of bleaching was achieved as in the reference experiments, which means that enzyme treatment has no adverse effect on the bleaching result.
    • Example 2
  • A diluted enzyme mixture (streptomyces hemicellulase) was added to 220 g of dry matter obtained from pine sulphate pulp (with a dry matter content of 30%) so that a mixture with a consistency of 10% and a xylanase activity of 5 U/g of pulp dry matter was obtained. The temperature in the enzyme treatment was 55 °C, the duration of treatment 2 h and pH 8.5.
  • After the enzyme treatment the pulp was washed in a Büchner funnel with a 20-fold amount of water.
  • After the washing, the pulp was subjected to an oxidating bleaching treatment using a mixture which contained 80 % chlorine dioxide and 20 % chlorine gas. The dosage of the mixture was 1.4 x kappa number of the pulp after enzyme treatment. Treatment temperature was 55 °C and duration of treatment 45 min. After the oxidating phase the pulp was washed in a Büchner funnel with a 20-fold amount of water.
  • Next, the pulp was subjected to an alkali treatment using a 5 % sodium hydroxide solution in a dosage of 0.9 x kappa. Consistency of the mixture was 2 %, treatment temperature 45-55 °C and duration of treatment 90 min. After the alkali treatment the pulp was washed in the same way as after the oxidation phase.
  • After this, the bleaching was continued by repeating the oxidation and alkali phases and then once more the oxidation phase and washing the pulp between these phases as described above. For the combined wash waters, the amount of organic­ally bound chlorine (AOX) and the chemical oxygen demand (COD) were determined, and these are presented in Table 2 (experiment 4) below.
  • In addition to the above-described experiment (exp. 4) il­lustrating the invention, three reference experiments (experiments 1-3) were carried out, and the AOX and COD values of the combined wash waters obtained from different stages of the experiments are also presented in Table 2. The experiments were performed as follows:
    • Experiment 3:
  • No enzyme treatment was employed. The dosage of bleaching chemicals in different phases of treatment during the bleaching was 2 x kappa, the commonly used dosage. In other respects, the experiment was analogous to that described above (exp. 4).
    • Experiment 2:
  • The pulp was treated with an enzyme as de­scribed above. The bleaching chemical used in the oxidation phases was pure chlorine gas, in a dosage of 2 x kappa. In other respects, the experiment was analogous to that de­scribed above (exp. 4.)
    • Experiment 1:
  • No enzyme treatment was employed. The bleach­ing chemical used in the oxidation phases was pure chlorine gas, in a dosage of 2 x kappa. In other respects, the experiment was analogous to that described above (exp. 4.) TABLE 2
    Bleaching AOX COD
    (kg/t of chemical pulp)
    Experiment 1 (reference)
    No enzyme treatment 4.0 71
    Cl₂ bleaching
    Experiment 2 (reference)
    Enzyme treatment, washing 2.9 63
    Cl₂ bleaching
    Experiment 3
    No enzyme treatment
    Bleaching with mixture 1.7 44
    80 % C10₂ + 20 % Cl₂
    Experiment 4
    Enzyme treatment, washing
    Bleaching with mixture 1.0 36
    80 % C10₂ + 20 % Cl₂
  • The results indicate that, in comparison to corresponding bleaching without enzyme treatment, enzyme treatment com­bined with chlorine dioxide bleaching as provided by the in­vention substantially reduces the pollution load caused by the spent bleach liquors as measured in terms of AOX and COD values. Compared to the commonly used chlorine bleaching, the improvement achieved is even more pronounced. It can also be seen that when used in conjunction with chlorine dioxide bleaching, enzyme treatment produces a much more distinct improvement than when used in conjunction with the conventional chlorine dioxide bleaching. It should be noted that in this case, too, the same degree of bleaching of the pulp was achieved in the experiment representing the inven­tion as in the reference experiments, which means that enzyme treatment had no adverse effect on the bleaching result.
  • It is obvious to a person skilled in the art that different embodiments of the invention are not restricted to the ex­amples described above, but that they may instead be varied within the scope of the following claims. For example, in the alkali treatment stages phases of the bleaching process, oxygen may be present in addition to the alkali, and the duration of the enzyme treatment may vary from a few minutes to several hours (e.g. 5 min. - 10 h).

Claims (10)

1. Procedure for the bleaching of pulp, in which procedure an oxidating bleaching chemical containing chlorine is used, characterized in that, in the oxidation stage, a chemical with a chlorine dioxide content of at least 50 % is used, that the pulp is subjected to enzyme treatment either in conjunction with or before the oxidation, and that, after the oxidation and enzyme treatment, the pulp is treated with an alkali.
2. Procedure according to claim 1, character­ized in that, in the oxidation stage, a chemical with a chlorine dioxide content of at least 70 % is used.
3. Procedure according to claim 1 or 2, character­ized in that the bleaching chemical used in the oxida­tion stage is a mixture containing chlorine gas in addition to chlorine dioxide.
4. Procedure according to any one of the preceding claims, characterized in that the pulp is treated with an enzyme and washed before the first oxidation stage.
5. Procedure according to any one of the preceding claims, characterized in that, after the oxidation stage, the pulp is washed, whereupon the bleaching process continues with an alkali treatment.
6. Procedure according to any one of the preceding claims, characterized in that the enzyme treatment is carried out in a temperature range of 10-90 °C, preferably 40-75 °C, with pH values in the range 3.0-10.0, preferably 4.0-9.0.
7. Procedure according to any one of the preceding claims, characterized in that the enzyme used is a hemicellulase, cellulase, pectinase, esterase or a mixture of these.
8. Use of an enzyme for reducing the chlorine content of the spent bleach liquor produced in the bleaching of pulp when an oxidating bleaching chemical with a chlorine dioxide content of at least 50 % is used.
9. Use of an enzyme according to claim 8 for reducing the chlorine content of the spent bleach liquor in the bleaching of pulp when a chemical containing chlorine gas and chlorine dioxide is used in the oxidation stage.
10. Use of a hemicellulase, cellulase, pectinase, esterase or a mixture of these for reducing the chlorine content of the spent bleach liquor produced in the bleaching of pulp.
EP89117235A 1989-02-14 1989-09-18 Procedure for the bleaching of pulp Revoked EP0383999B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT89117235T ATE103351T1 (en) 1989-02-14 1989-09-18 METHOD OF BLEACHING PULP.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI890700A FI90888B (en) 1989-02-14 1989-02-14 Method for bleaching cellulose pulp
FI890700 1989-02-14

Publications (3)

Publication Number Publication Date
EP0383999A2 true EP0383999A2 (en) 1990-08-29
EP0383999A3 EP0383999A3 (en) 1990-12-12
EP0383999B1 EP0383999B1 (en) 1994-03-23

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ID=8527891

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EP89117235A Revoked EP0383999B1 (en) 1989-02-14 1989-09-18 Procedure for the bleaching of pulp

Country Status (8)

Country Link
EP (1) EP0383999B1 (en)
JP (1) JPH02221482A (en)
AT (1) ATE103351T1 (en)
CA (1) CA1339594C (en)
DE (1) DE68914135D1 (en)
ES (1) ES2050747T3 (en)
FI (1) FI90888B (en)
NO (1) NO176406C (en)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1991011553A1 (en) * 1990-02-02 1991-08-08 Enso-Gutzeit Oy A process for the bleaching of chemical pulp
WO1992003608A1 (en) * 1990-08-24 1992-03-05 Novo Nordisk A/S Process for treatment of lignocellulosic pulp and apparatus for performance of the process
GB2248075A (en) * 1990-09-11 1992-03-25 Sandoz Ltd Bleaching chemical pulp
WO1992021813A1 (en) * 1991-06-07 1992-12-10 Ici Canada Inc. Biobleaching process
EP0395792B1 (en) * 1989-05-04 1993-07-14 Enso-Gutzeit Oy Procedure for the bleaching of pulp
US5231022A (en) * 1990-07-24 1993-07-27 Showa Denko K.K. Cellulase isolated from bacillus ferm bp-3431 or a mutant strain thereof
US5369024A (en) * 1992-03-25 1994-11-29 The United States Of America As Represented By The Secretary Of Agriculture Xylanase from streptomyces roseiscleroticus NRRL-11019 for removing color from kraft wood pulps
US5434071A (en) * 1990-01-10 1995-07-18 Korsnas Aktiebolag α-L-arabinofuranosidase and xylanase from Bacillus stearothermophilus NCIMB 40221, NCIMB 40222 or mutant thereof for delignification
WO1995035405A1 (en) * 1994-06-17 1995-12-28 Melitta Haushaltsprodukte Gmbh & Co. Kommanditgesellschaft Process for delignification and bleaching of unbleached cellulose suspensions or such which have been pre-bleached in an alkaline medium
US5498534A (en) * 1992-03-25 1996-03-12 The United States Of America As Represented By The Secretary Of Agriculture Method of removing color from wood pulp using xylanase from streptomyces roseiscleroticus NRRL B-11019
US5591304A (en) * 1991-05-07 1997-01-07 Von Kreisler Selting Werner Method for the use of enzymes in bleaching paper pulp
US5837515A (en) * 1990-05-16 1998-11-17 Alko-Yhtiot Oy Enzyme preparations and methods for their production
US5871730A (en) * 1994-07-29 1999-02-16 Universite De Sherbrooke Thermostable xylanase DNA, protein and methods of use
US5935836A (en) * 1994-07-29 1999-08-10 Rohm Enzyme Finland Oy Actinomadura xylanase sequences and methods of use
US6300114B1 (en) 1994-07-29 2001-10-09 Rohm Enzyme Finland Oy Sequences of xylanase and xylanase expression vectors
WO2003074780A1 (en) * 2002-03-06 2003-09-12 Iogen Bio-Products Corporation Xylanase treatment of chemical pulp
US7320741B2 (en) 2001-01-18 2008-01-22 Iogen Bio-Products Corporation Method of xylanase treatment in a chlorine dioxide bleaching sequence
US7816129B2 (en) 1994-07-29 2010-10-19 Ab Enzymes Gmbh Production and secretion of proteins of bacterial origin in filamentous fungi

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CA1086905A (en) * 1977-10-25 1980-10-07 W. Howard Rapson Bleach plant operation
WO1989008738A1 (en) * 1988-03-14 1989-09-21 Cultor Oy Procedure for bleaching cellulose pulp

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Publication number Priority date Publication date Assignee Title
JPS5468402A (en) * 1977-11-09 1979-06-01 Kogyo Gijutsuin Property modification of biochemical pulp

Patent Citations (2)

* Cited by examiner, † Cited by third party
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Cited By (25)

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EP0395792B1 (en) * 1989-05-04 1993-07-14 Enso-Gutzeit Oy Procedure for the bleaching of pulp
US5434071A (en) * 1990-01-10 1995-07-18 Korsnas Aktiebolag α-L-arabinofuranosidase and xylanase from Bacillus stearothermophilus NCIMB 40221, NCIMB 40222 or mutant thereof for delignification
WO1991011553A1 (en) * 1990-02-02 1991-08-08 Enso-Gutzeit Oy A process for the bleaching of chemical pulp
US5837515A (en) * 1990-05-16 1998-11-17 Alko-Yhtiot Oy Enzyme preparations and methods for their production
US5231022A (en) * 1990-07-24 1993-07-27 Showa Denko K.K. Cellulase isolated from bacillus ferm bp-3431 or a mutant strain thereof
US5314637A (en) * 1990-07-24 1994-05-24 Showa Denko K.K. Detergent comprising isolated cellulase from bacillus ferm bp-3431 or a mutant strain thereof, surfactant and builder
US5318905A (en) * 1990-07-24 1994-06-07 Showa Denko K.K. Composition containing celluase from Bacillus Ferm BP-3431 or a mutant strain thereof, and paper pulp and method of using celluase to treat paper pulp slurry
WO1992003608A1 (en) * 1990-08-24 1992-03-05 Novo Nordisk A/S Process for treatment of lignocellulosic pulp and apparatus for performance of the process
GB2248075A (en) * 1990-09-11 1992-03-25 Sandoz Ltd Bleaching chemical pulp
GB2248075B (en) * 1990-09-11 1994-06-29 Sandoz Ltd Chlorine-free process for bleaching pulp
US5591304A (en) * 1991-05-07 1997-01-07 Von Kreisler Selting Werner Method for the use of enzymes in bleaching paper pulp
WO1992021813A1 (en) * 1991-06-07 1992-12-10 Ici Canada Inc. Biobleaching process
US5498534A (en) * 1992-03-25 1996-03-12 The United States Of America As Represented By The Secretary Of Agriculture Method of removing color from wood pulp using xylanase from streptomyces roseiscleroticus NRRL B-11019
US5834301A (en) * 1992-03-25 1998-11-10 The United States Of America As Represented By The Secretary Of Agriculture Method of removing color from kraft wood pulps
US5369024A (en) * 1992-03-25 1994-11-29 The United States Of America As Represented By The Secretary Of Agriculture Xylanase from streptomyces roseiscleroticus NRRL-11019 for removing color from kraft wood pulps
WO1995035405A1 (en) * 1994-06-17 1995-12-28 Melitta Haushaltsprodukte Gmbh & Co. Kommanditgesellschaft Process for delignification and bleaching of unbleached cellulose suspensions or such which have been pre-bleached in an alkaline medium
US5871730A (en) * 1994-07-29 1999-02-16 Universite De Sherbrooke Thermostable xylanase DNA, protein and methods of use
US5935836A (en) * 1994-07-29 1999-08-10 Rohm Enzyme Finland Oy Actinomadura xylanase sequences and methods of use
US6300114B1 (en) 1994-07-29 2001-10-09 Rohm Enzyme Finland Oy Sequences of xylanase and xylanase expression vectors
US6506593B2 (en) 1994-07-29 2003-01-14 Rohm Enzyme Finland Oy Production and secretion of proteins of bacterial origin in filamentous fungi
US6667170B1 (en) 1994-07-29 2003-12-23 Röhm Enzyme Finland OY Sequences of Xylanase and Xylanase expression vectors
US7816129B2 (en) 1994-07-29 2010-10-19 Ab Enzymes Gmbh Production and secretion of proteins of bacterial origin in filamentous fungi
US7320741B2 (en) 2001-01-18 2008-01-22 Iogen Bio-Products Corporation Method of xylanase treatment in a chlorine dioxide bleaching sequence
WO2003074780A1 (en) * 2002-03-06 2003-09-12 Iogen Bio-Products Corporation Xylanase treatment of chemical pulp
US7368036B2 (en) 2002-03-06 2008-05-06 Iogen Bio-Products Corporation Xylanase treatment of chemical pulp

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Publication number Publication date
ATE103351T1 (en) 1994-04-15
NO893714D0 (en) 1989-09-18
NO893714L (en) 1990-08-15
ES2050747T3 (en) 1994-06-01
CA1339594C (en) 1997-12-23
NO176406C (en) 1995-03-29
FI890700A (en) 1990-08-15
EP0383999A3 (en) 1990-12-12
EP0383999B1 (en) 1994-03-23
NO176406B (en) 1994-12-19
FI90888B (en) 1993-12-31
DE68914135D1 (en) 1994-04-28
JPH02221482A (en) 1990-09-04
FI890700A0 (en) 1989-02-14

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