US20050155729A1 - Method for ozone treatment of used paper - Google Patents

Method for ozone treatment of used paper Download PDF

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Publication number
US20050155729A1
US20050155729A1 US10/504,806 US50480604A US2005155729A1 US 20050155729 A1 US20050155729 A1 US 20050155729A1 US 50480604 A US50480604 A US 50480604A US 2005155729 A1 US2005155729 A1 US 2005155729A1
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Prior art keywords
paper
ozone
pulp
ozonization
gas mixture
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Abandoned
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US10/504,806
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English (en)
Inventor
Alain Trichet
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LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Original Assignee
LAir Liquide SA a Directoire et Conseil de Surveillance pour lEtude et lExploitation des Procedes Georges Claude
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Application filed by LAir Liquide SA a Directoire et Conseil de Surveillance pour lEtude et lExploitation des Procedes Georges Claude filed Critical LAir Liquide SA a Directoire et Conseil de Surveillance pour lEtude et lExploitation des Procedes Georges Claude
Assigned to L'AIR LIQUIDE, SOCIETE ANONYME A DIRECTOIR ET CONSEIL DE SURVEILLANCE POUR I'ETUDE ET I'EXPLOITATION DES PROCEDES GEORGES CLAUDE reassignment L'AIR LIQUIDE, SOCIETE ANONYME A DIRECTOIR ET CONSEIL DE SURVEILLANCE POUR I'ETUDE ET I'EXPLOITATION DES PROCEDES GEORGES CLAUDE ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: TRICHET, ALAIN
Publication of US20050155729A1 publication Critical patent/US20050155729A1/en
Abandoned legal-status Critical Current

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    • 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
    • D21C9/147—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications
    • D21C9/153—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications with ozone
    • 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
    • D21C5/02—Working-up waste paper
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/64—Paper recycling

Definitions

  • the invention relates to a method for treating used paper.
  • Used paper is recovered and treated to produce new paper sheets or new paper or cardboard packaging materials, for example.
  • the present method for treating used paper for the recycling thereof begins with pulping of the paper recovered for recycling.
  • This pulp is screened one or more times to remove the coarse particles such as paperclips, staples, coarse ink particles, etc.
  • the printing ink consists of organic or inorganic dyes and organic binders which, on drying, imprison the dye particles and maintain them on the paper.
  • used paper is often coated with glues or adhesives, for example binding glues and adhesives for sealing envelopes.
  • Used paper is also soiled, by food and other materials; the pulp obtained therefore contains microorganisms such as bacteria, fungi, yeasts, and enzymes such as the enzyme catalase.
  • Caustic soda is introduced in particular to swell the paper fibers and to permit a better separation of the solids.
  • Hydrogen peroxide and/or oxidizing chlorine products are also added to destroy the microorganisms and to improve deinking.
  • Chelating agents, such as sodium silicate, of which the action mechanism is poorly known, are also added to further facilitate deinking. They form complexes with the binders and dyes which are then more easily removed.
  • Hydrogen peroxide and/or chlorine products have the function not only of destroying the microorganisms present in the pulp but also of purifying the circuits of the installation. However, since hydrogen peroxide is destroyed by the catalase enzyme present in the pulp, this causes high overconsumption of this compound during bleaching.
  • a series of mixings is accordingly carried out, followed by flotations of the pulp, to remove the fine ink particles mechanically or at least to coat them in the mass of the pulp in order to obtain a uniform “whiteness”.
  • Used paper to be recycled generally consists of a mixture of papers of different types: newspapers, lined papers, magazines or higher grade papers.
  • the pulp obtained can be subjected to a bleaching step.
  • This bleaching step is carried out, as for new paper pulps, by treatment with oxidants such as hydrogen peroxide or chlorine products, or with reducing agents such as sodium dithionite.
  • Used paper may also contain paper that has been treated with optical brighteners (optical brighteners are fluorescent compounds that make the paper appear whiter via an optical mechanism), and these fluorescent compounds have been suspected of being carcinogenic; it may therefore be desirable to proceed with a defluorescence of the pulp, and, here also, hydrogen peroxide is used.
  • optical brighteners are fluorescent compounds that make the paper appear whiter via an optical mechanism
  • these fluorescent compounds have been suspected of being carcinogenic; it may therefore be desirable to proceed with a defluorescence of the pulp, and, here also, hydrogen peroxide is used.
  • the pulp is then converted into paper sheets by known methods.
  • ozone has been used for treating used paper.
  • ozone treatments are performed after the flotation steps, that is during the subsequent bleaching and defluorescence steps.
  • ozone is always used as a supplement to other chemicals, that is hydrogen peroxide, chlorine products, caustic soda, and the chelating agents already present in the method.
  • this method is highly pollutant because of the many chemicals used, which are found in the effluents discharged by the used paper treatment plants.
  • the flotation step for deinking purposes may not be sufficient and, as it has been observed, it then becomes necessary to carry out a plurality of mixing steps followed by flotation steps to complete the deinking.
  • the deinking step which is aimed at removing the printing ink present on the used paper to be treated and serves to obtain a corresponding whiteness close to that of the original paper
  • the actual bleaching step which is practised both on pulps produced from used paper and on new paper pulps, that is obtained directly from cellulose.
  • the bleaching as such consists in removing the lignin present in the pulp (new or recycled).
  • the deinking step is unnecessary in the case of new paper pulps.
  • the invention further proposes a method for treating waste paper which serves to significantly reduce the pollution of the effluents discharged by the treatment plants.
  • the invention proposes a method for treating used paper of the type comprising the successive steps of: a) pulping of the used paper in an aqueous medium, b) at least one screening to remove coarse particles, c) at least one flotation to deink the pulp, characterized in that it further comprises an ozonization step d) carried out at the latest before the flotation step c).
  • the ozonization step d) is carried out at a used-paper pulp consistency of between 0.5 and 5%.
  • the ozonization step d) is carried out at a used-paper pulp consistency of 0.5 to 3%.
  • the steps a), b), c) and d) are carried out in water, without the addition of chemicals other than ozone in step d).
  • the steps a), b), c) and d) are carried out in the presence of caustic soda, hydrogen peroxide and/or chlorine products, sodium silicate and/or chelating agents.
  • the step d) is preferably carried out after the screening step b).
  • the ozonization step d) is carried out in a two-phase tubular contactor of the gas-liquid type.
  • the ozonization step d) is carried out in the tubular contactor operating in wave mode.
  • the ozonization step d) is carried out in the tubular contactor operating in plug mode.
  • the ozonization step d) is carried out with an air-ozone or oxygen-ozone gas mixture comprising between 50 and 200 g of ozone per m 3 of gas mixture.
  • the ozonization step d) is carried out in a two-phase gas-liquid tubular contactor in which the ozone is introduced in the form of an air-ozone or oxygen-ozone gas mixture at a rate above 0.5 m/s and less than or equal to 10 m/s while the used-paper pulp is introduced at a rate above 0.5 m/s and less than or equal to 10 m/s.
  • the ozonization step d) is carried out in a two-phase tubular contactor in which the ozone is introduced in the form of an air-ozone or oxygen-ozone gas mixture at a rate between 0.5 and 2 m/s while the used-paper pulp is introduced at a rate between 0.5 and 2 m/s.
  • FIG. 1 shows an enlarged view of a particle of printing ink bonded to the surface of a used paper
  • FIG. 2 shows an enlarged view of the ink particle of FIG. 1 , on the same scale, after the deinking step of the prior art method
  • FIG. 3 shows an enlarged view of the ink particle of FIG. 1 , on the same scale, after the deinking step of the method of the invention
  • FIG. 4 shows a cross section of a two-phase gas-liquid tubular contactor in segregated mode
  • FIG. 5 shows a cross section of a two-phase liquid-gas tubular contactor in wave mode
  • FIG. 6 shows a cross section of a two-phase gas-liquid tubular contactor in plug mode
  • FIG. 7 shows a cross section of a two-phase gas-liquid tubular contactor in dispersed bubble mode
  • FIG. 8 shows, in the form of bar graphs, the number of points of ink remaining, as a function of their size, in a used-paper pulp after the screening step ( FIG. 8A ), the ozonization step ( FIG. 8B ), and the flotation step ( FIG. 8C ), according to a first embodiment of the method of the invention, and
  • FIG. 9 shows, in the form of bar graphs, the number and size of the points of ink remaining in a used-paper pulp after the screening step ( FIG. 9A ), the flotation step ( FIG. 9B ) and the ozonization step ( FIG. 9C ), carried out according to the prior art method.
  • the method for treating used paper to be recycled according to the invention comprises, like the method for treating used paper of the prior art, a step of pulping of the mass of paper to be recycled in an aqueous medium. The pulp then undergoes a plurality of solid-solid separation steps in order to remove the undesirable elements such as paperclips, staples and coarse ink particles.
  • At least one screening step is carried out.
  • Chelating agents such as sodium silicate are also added to complex the metals, originating for example from the dyes of the printing inks, in order to be able to subsequently remove them with hydrogen peroxide or the chlorine products already mentioned. Any other chemical may be added, as known in the art.
  • the method for treating used paper of the invention differs from the method of the prior art in that, at the latest before the flotation steps, the paper pulp is subjected to an ozonization step.
  • This ozonization step serves to improve the effectiveness of the flotation steps for deinking the paper pulp and, moreover, it destroys the microorganisms and, above all, the catalase enzyme.
  • the deinking step by flotation by flotation more effective, the number and duration of the subsequent treatment steps intended to further complete the deinking, for example by carrying out a series of mixings followed by flotations, are reduced in comparison with the prior art or indeed eliminated.
  • ozone destroys the catalase enzyme which reduces the activity of the hydrogen peroxide, this eliminates the overconsumption of hydrogen peroxide in the event that the hydrogen peroxide treatment step is maintained.
  • the high reactivity of ozone enables it to degrade the unsaturated products with which the waste paper is impregnated.
  • the ozone used in the method of the invention is used to react with the unsaturated products impregnating the used paper and less with the lignin present, because the latter is “coated” by these products and others such as mineral fillers.
  • printing inks consist of particles of carbon or another dye dispersed in a liquid binder.
  • the binder dries, it coats the carbon particles and other particles and fixes them to the surface of the paper sheet.
  • FIG. 1 shows an enlarged cross section of a particle of dried printing ink on the paper surface.
  • the carbon particle 2 is enveloped and bonded to the paper surface 3 by the dried binder 1 .
  • FIG. 2 shows a cross section of the ink particle of FIG. 1 , on the same scale, after the pulping, screening and flotation steps according to the prior art method.
  • the carbon particle 2 is still coated and bonded to the paper surface 3 by the binder 1 ′ which has decreased in thickness.
  • the mechanical action necessary to detach this ink particle 2 from the paper surface 3 is less than that required to separate the ink particle 2 shown in FIG. 2 .
  • the number of mixing-flotation steps necessary to completely deink the paper to be recycled according to the method of the invention is smaller.
  • the ozone destroys the microorganisms and, above all, the catalase enzyme. Since catalase enzyme destroys the activity of the hydrogen peroxide used in the prior art method, this allows a more effective use of the hydrogen peroxide. Its overconsumption is decreased, and it can even be eliminated for certain end uses of the paper.
  • the ozone also serves to clean up the circuits of the installation to which the method for treating used paper is put into practice.
  • the ozone can be used without adding any of the reagents commonly used in the prior art method.
  • the method of the invention in a particularly advantageous embodiment, hence consists in pulping the mass of paper to be recycled, in water, in proceeding with the solid-solid separation steps by screening followed by the flotation steps, always exclusively in water and without the addition of any reagent, provided that an ozonization step is put into practice at the latest before the flotation steps.
  • This method which uses ozone only without other chemical reagents, offers considerable advantages, its simplicity and its economy, and, furthermore, it is a method for treating used paper from which the effluents have a very low level of pollution.
  • the ozonization step must be carried out at the latest before the flotation step for deinking. It can be carried out before, during or just after the pulping step or after the screening step.
  • the screening step is carried out after the screening step in order to permit good contact between the ozone and the pulp to be treated, for greater effectiveness of the ozone; the coarse particles and undesirable elements can be removed easily by the screening, and the ozone is therefore used more efficiently and without overconsumption to remove the fine ink particles, purify the installation circuits and/or react with certain additives.
  • the effectiveness and extent of the degradation of the products to be removed in the used paper for the same contact time depend on the extent and effectiveness of the contacting of the ozone with the products to be degraded. In other words, the effectiveness of the ozonization reaction depends on the rate of dissolution of the ozone in the pulp.
  • ozone has already been used in methods for producing paper pulps to bleach virgin pulps. At the present time, these ozonization methods take place at a solids concentration between 8 and 40 g of solids per 100 g of pulp.
  • the paper pulps are treated as a liquid medium, generally an aqueous medium, in which the solid particles are in suspension.
  • the ozonization reaction therefore produces a situation of a two-phase mixture: a gas phase and a liquid phase containing solids. Since the chemical ozonization reaction is fast, it is necessary to have a very rapid gas dissolution rate in the liquid phase containing the solids so that the ozone reacts with the solids.
  • low consistency paper pulp means a paper pulp in which the paper concentration is between 0.5 and 5% by weight of the total weight of the pulp.
  • very low consistency paper pulp means a paper pulp in which the paper concentration is about 1% by weight of the total weight of the pulp.
  • two-phase gas-liquid tubular contactors which serve to obtain very high gas dissolution rates in the paper pulp.
  • the invention proposes to put the ozonization step into practice in a two-phase tubular contactor of the gas-liquid type and to introduce the paper pulp at low or very low consistency.
  • the tubular contactor for putting into practice the method of the invention can be a horizontal or vertical tubular contactor operating in cocurrent flow of the liquid phase containing the solids.
  • the gas can be introduced via a simple pipe or via a more sophisticated system, for example a static mixer.
  • the ozone dissolution rate in the paper pulp depends on the gas-liquid mass transfer coefficients and, more particularly, on the interfacial area between the two phases.
  • the aim here is to obtain a good gas-pulp emulsion.
  • the reactor will operate in segregated mode, in wave mode, in plug mode or in dispersed bubble mode.
  • FIG. 4 shows a cross section of a horizontal tubular contactor T operating in segregated mode in which the gas phase has the numeral 4 and the pulp has the numeral 6 .
  • the interfacial area is shown by the contact surface 5 between the gas phase 4 and the pulp 6 .
  • This contact surface 5 when the tubular contactor T is in segregated mode, as shown in FIG. 4 , can be treated as a plane surface.
  • the interfacial area corresponding to the contact surface 5 is smaller than in the cases shown in FIGS. 5 to 7 , which are discussed below. For this reason, the ozone dissolution rate is less favorable.
  • Such a segregated mode is obtained when the respective rates of introduction of the gas phase and the pulp are lower than 1 m/s, more particularly higher than 0.5 m/s and lower than 1 m/s.
  • the contact surface between the gas phase and the liquid phase containing solids is improved when the contactor T operates in wave mode, as shown in FIG. 5 .
  • the contact surface with the numeral 5 ′ between the gas phase 4 and the pulp forms waves. It is increased in this domain. Hence the gas is dissolved more rapidly in this case than in the case shown in FIG. 4 , that is in segregated mode.
  • the ozone dissolution rate, and hence the reaction rate of the ozone with the pulp, is further improved when, as shown in FIG. 6 , the tubular contactor T operates in plug mode.
  • the pulp 6 is actuated with a movement which makes it touch the two inside horizontal walls of the contactor.
  • the gas phase 4 therefore has a large contact surface with the numeral 5 ′′ for contact with the pulp 6 when the contactor operates in such a plug mode.
  • the contactor T operates in wave mode or in plug mode when the respective gas phase and pulp introduction rates are between 1 and 2 m/s.
  • Such a dispersed bubble mode is obtained for respective gas and pulp introduction rates above 2 m/s and up to 10 m/s.
  • the ozonization step can be put into practice in the contactor T operating in segregated mode, in wave mode, in plug mode or in dispersed bubble mode, it is preferably put into practice in wave mode or in plug mode, that is with gas introduction rates between 0.5 and 2 m/s and pulp introduction rates between 0.5 and 2 m/s.
  • the introduction rates mentioned above and below are rates obtained when the contactor T is empty.
  • the gas introduction rate is calculated as a function of the internal cross section of the contactor used, in order to obtain a gas introduction rate between 0.5 and 2 m/s when the contactor contains no pulp.
  • the pulp introduction rate is calculated as a function of its introduction rate in the empty contactor and as a function of the internal cross section of the contactor.
  • ozone is highly reactive and the quantities of ozone to be consumed are generally small.
  • a carrier gas such as air
  • an oxygen-ozone or nitrogen-ozone gas mixture or any other mixture of ozone in a carrier gas compatible with ozone can also be used.
  • the mixture is stirred in a pulper marketed by Lamort for 20 min.
  • the pH is close to 10.5.
  • the paper pulp obtained is then screened through screens, following the usual methods of the profession.
  • the ozonization is carried out at a consistency of 3% in a glass reactor, the ozone is introduced in the form of an oxygen-ozone gas mixture containing 150 g of ozone per m 3 of gas mixture, until 10 kg of ozone are consumed per metric ton of dry paper.
  • the pulp obtained is diluted to a consistency of 1% and transferred to a Lamort type flotation cell.
  • the flotation is carried out for 6 min and prolonged for 4 min.
  • a foaming agent is added.
  • the number and size of the black spots was also measured on each sheet per m 2 of surface area.
  • the number of black spots per m 2 and the size in microns of these black spots were determined by image analysis.
  • the method was followed as in example 1 but without adding hydrogen peroxide, caustic soda and sodium silicate.
  • the pH was close to 7.5.
  • Measurements were taken of the whiteness with and without UV, of the fluorescence and the number of black spots per m 2 of sheets of paper obtained by this method, as well as their size in microns, on each sheet of paper obtained after the screening step, after the flotation step and after the ozonization step.
  • the method is followed as in example 2, without the addition of any chemical reagent other than ozone but by carrying out the ozonization step after the flotation step.
  • test in example 2 was reproduced using a horizontal stainless steel tubular contactor having an inside diameter of 4.5 cm and a length of 100 m supplied with a used-paper pulp with a consistency of 2.5%.
  • the paper pulp introduction rate was selected in order to obtain pulp rates (in empty contactor) between 1 and 2 m/s.
  • the same rates were used for the gas mixture consisting of a mixture of oxygen and ozone having an ozone content of 100 g/m 3 of mixture.
  • the ozone transfer capacity is accordingly 1.5 to 3 kg/t of pulp for a residence time of one-and-a-half minutes.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)
US10/504,806 2002-02-18 2003-02-13 Method for ozone treatment of used paper Abandoned US20050155729A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR0202062A FR2836162B1 (fr) 2002-02-18 2002-02-18 Procede de traitement de papiers uses par l'ozone
FR02/02062 2002-02-18
PCT/FR2003/000460 WO2003071024A2 (fr) 2002-02-18 2003-02-13 Procede de traitement de papiers uses par l'ozone

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US20050155729A1 true US20050155729A1 (en) 2005-07-21

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US10/504,806 Abandoned US20050155729A1 (en) 2002-02-18 2003-02-13 Method for ozone treatment of used paper

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US (1) US20050155729A1 (de)
EP (1) EP1478802A2 (de)
JP (1) JP2005517834A (de)
AU (1) AU2003222375A1 (de)
CA (1) CA2475689A1 (de)
FR (1) FR2836162B1 (de)
WO (1) WO2003071024A2 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008048670A1 (de) * 2008-09-24 2010-03-25 Voith Patent Gmbh Abwasserbehandlung

Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2916412A (en) * 1953-11-17 1959-12-08 Butler Co Method of deinking waste paper
US4216054A (en) * 1977-09-26 1980-08-05 Weyerhaeuser Company Low-consistency ozone delignification
US5211809A (en) * 1991-05-21 1993-05-18 Air Products And Chemicals, Inc,. Dye removal in oxygen color stripping of secondary fibers
US5234544A (en) * 1989-10-18 1993-08-10 Air Products And Chemicals, Inc. Cleaning and bleaching of secondary fiber
US5387317A (en) * 1993-01-28 1995-02-07 The Mead Corporation Oxygen/ozone/peracetic aicd delignification and bleaching of cellulosic pulps
US5397434A (en) * 1992-06-08 1995-03-14 Air Products And Chemicals, Inc. Method for distributing cellulosic pulp through a reactor at a constant upward velocity
US5397480A (en) * 1992-03-23 1995-03-14 Dickerson; J. Rodney Purification of aqueous streams
US5399261A (en) * 1990-05-31 1995-03-21 Gie Anjou-Recherche Installation for the treatment of flows of liquids with monophase contactor and recirculating-degassing device
US5472567A (en) * 1990-08-28 1995-12-05 Kamyr, Inc. Method of chemically reacting a slurry with a gas
US5529660A (en) * 1994-04-15 1996-06-25 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Calude Method of reducing fluorescence in deinked pulp by treating pulp with ozone and a bleaching agent
US6071380A (en) * 1994-08-31 2000-06-06 Hoffman Environmental Systems, Inc. Method of papermaking having zero liquid discharge
US6277239B1 (en) * 1998-01-23 2001-08-21 Voith Sulzer Papiertechnik Patent Gmbh Process for removing fine impurities from a fibrous suspension
US20020139755A1 (en) * 2001-03-28 2002-10-03 Green Lawrence M. Gas-liquid contact apparatus
US20050109475A1 (en) * 2002-02-18 2005-05-26 Alain Trichet Method for ozone treatment of a liquid phase containing solid particles
US6982006B1 (en) * 1999-10-19 2006-01-03 Boyers David G Method and apparatus for treating a substrate with an ozone-solvent solution

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2708009B1 (fr) * 1993-07-19 1995-09-08 Papeteries Matussiere Forest Procédé de désencrage de papiers de récupération.
FR2801327B1 (fr) * 1999-11-18 2002-07-12 Papeteries Matussiere Forest Procede de desencrage, de decoloration, de desinfection et de blanchiment de papiers de recuperation

Patent Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2916412A (en) * 1953-11-17 1959-12-08 Butler Co Method of deinking waste paper
US4216054A (en) * 1977-09-26 1980-08-05 Weyerhaeuser Company Low-consistency ozone delignification
US5234544A (en) * 1989-10-18 1993-08-10 Air Products And Chemicals, Inc. Cleaning and bleaching of secondary fiber
US5399261A (en) * 1990-05-31 1995-03-21 Gie Anjou-Recherche Installation for the treatment of flows of liquids with monophase contactor and recirculating-degassing device
US5472567A (en) * 1990-08-28 1995-12-05 Kamyr, Inc. Method of chemically reacting a slurry with a gas
US5211809A (en) * 1991-05-21 1993-05-18 Air Products And Chemicals, Inc,. Dye removal in oxygen color stripping of secondary fibers
US5397480A (en) * 1992-03-23 1995-03-14 Dickerson; J. Rodney Purification of aqueous streams
US5397434A (en) * 1992-06-08 1995-03-14 Air Products And Chemicals, Inc. Method for distributing cellulosic pulp through a reactor at a constant upward velocity
US5387317A (en) * 1993-01-28 1995-02-07 The Mead Corporation Oxygen/ozone/peracetic aicd delignification and bleaching of cellulosic pulps
US5529660A (en) * 1994-04-15 1996-06-25 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Calude Method of reducing fluorescence in deinked pulp by treating pulp with ozone and a bleaching agent
US6071380A (en) * 1994-08-31 2000-06-06 Hoffman Environmental Systems, Inc. Method of papermaking having zero liquid discharge
US6277239B1 (en) * 1998-01-23 2001-08-21 Voith Sulzer Papiertechnik Patent Gmbh Process for removing fine impurities from a fibrous suspension
US6982006B1 (en) * 1999-10-19 2006-01-03 Boyers David G Method and apparatus for treating a substrate with an ozone-solvent solution
US20020139755A1 (en) * 2001-03-28 2002-10-03 Green Lawrence M. Gas-liquid contact apparatus
US20050109475A1 (en) * 2002-02-18 2005-05-26 Alain Trichet Method for ozone treatment of a liquid phase containing solid particles

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008048670A1 (de) * 2008-09-24 2010-03-25 Voith Patent Gmbh Abwasserbehandlung

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Publication number Publication date
FR2836162A1 (fr) 2003-08-22
WO2003071024A3 (fr) 2004-03-25
AU2003222375A8 (en) 2003-09-09
FR2836162B1 (fr) 2004-05-07
EP1478802A2 (de) 2004-11-24
AU2003222375A1 (en) 2003-09-09
WO2003071024A2 (fr) 2003-08-28
JP2005517834A (ja) 2005-06-16
CA2475689A1 (fr) 2003-08-28

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