WO2008024828A9 - Procédé et appareil destinés à l'utilisation de dioxyde de chlore pour prévenir la biosalissure de membranes utilisées dans le traitement de l'eau - Google Patents

Procédé et appareil destinés à l'utilisation de dioxyde de chlore pour prévenir la biosalissure de membranes utilisées dans le traitement de l'eau

Info

Publication number
WO2008024828A9
WO2008024828A9 PCT/US2007/076500 US2007076500W WO2008024828A9 WO 2008024828 A9 WO2008024828 A9 WO 2008024828A9 US 2007076500 W US2007076500 W US 2007076500W WO 2008024828 A9 WO2008024828 A9 WO 2008024828A9
Authority
WO
WIPO (PCT)
Prior art keywords
water
chlorine dioxide
membrane
chlorine
purification plant
Prior art date
Application number
PCT/US2007/076500
Other languages
English (en)
Other versions
WO2008024828A1 (fr
Inventor
Thomas Ellsworth Mcwhorter
Aaron A Rosenblatt
Jack Anderton
Dean Gregory
Jerry Elwell
Original Assignee
Cdg Technology Inc
Thomas Ellsworth Mcwhorter
Aaron A Rosenblatt
Jack Anderton
Dean Gregory
Jerry Elwell
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Cdg Technology Inc, Thomas Ellsworth Mcwhorter, Aaron A Rosenblatt, Jack Anderton, Dean Gregory, Jerry Elwell filed Critical Cdg Technology Inc
Publication of WO2008024828A1 publication Critical patent/WO2008024828A1/fr
Publication of WO2008024828A9 publication Critical patent/WO2008024828A9/fr

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B11/00—Oxides or oxyacids of halogens; Salts thereof
    • C01B11/02—Oxides of chlorine
    • C01B11/022—Chlorine dioxide (ClO2)
    • C01B11/023—Preparation from chlorites or chlorates
    • C01B11/024—Preparation from chlorites or chlorates from chlorites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D65/00—Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes
    • B01D65/02—Membrane cleaning or sterilisation ; Membrane regeneration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D65/00—Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes
    • B01D65/08—Prevention of membrane fouling or of concentration polarisation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/76—Treatment of water, waste water, or sewage by oxidation with halogens or compounds of halogens
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2311/00—Details relating to membrane separation process operations and control
    • B01D2311/04—Specific process operations in the feed stream; Feed pretreatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2321/00—Details relating to membrane cleaning, regeneration, sterilization or to the prevention of fouling
    • B01D2321/16—Use of chemical agents
    • B01D2321/168—Use of other chemical agents
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/16—Regeneration of sorbents, filters
    • 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
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/30—Wastewater or sewage treatment systems using renewable energies
    • Y02W10/37—Wastewater or sewage treatment systems using renewable energies using solar energy

Definitions

  • Membranes suitable for water filtration are typically polymeric films, formed into monolayers or multi-layers. In the most common configurations, membranes are either arranged as flat sheets, wound in a spiral configuration with porous layers between the membrane sheets to conduct the various streams of water, or arranged as flat sheets backed by a porous substrate in a plate and frame type construction. They may also be produced in the form of hollow fibers or in tubular configurations.
  • membranes are porous and allow water to permeate while blocking the passage of contaminants.
  • Membrane permeability is a function of pore size as well as other characteristics, such as hydrophobicity or hydrophilicity.
  • the effective "pore size" determines the relative rates at which different materials permeate.
  • membranes are made with relatively large sized pores so that water and dissolved materials can pass while microscopic particles like bacteria and viruses do not.
  • Membranes having intermediate sized pores are typically used for removing particles and large organic molecules.
  • Membranes having relatively small pores allow water permeation but interfere with or block the passage of dissolved minerals. These "tight" membranes are typically used for desalination of seawater or brackish water.
  • contaminated water is fed under pressure to one side of the membrane. Pressure is used to overcome the frictional resistance to flow as well as the osmotic pressure that exists between water at a high salt concentration versus low concentration. The pressure causes water to flow from the contaminated side of the membrane to the clean side. As this occurs, the contaminants, such as salt, in the feedwater is progressively concentrated. Water having increased concentrations of contaminants is known as "blowdown.” [0005] There is a limit to the amount of feed water that can be recovered in the permeate.
  • the local concentration of contaminants in the water on the feed/blow-down side of the membrane be kept as low as possible to minimize membrane fouling, maintain osmotic pressure at relatively low levels and avoid the build up of contaminants on the membrane surface.
  • the water on the feed/blowdown side of the membrane is generally kept circulating at a substantial velocity to sweep away the contaminants that would otherwise concentrate in the boundary layer of the membrane surface.
  • bacteria can still become lodged on the membrane and form a bio-film.
  • bacteria become attached to the membrane surface and begin to grow on available nutrients.
  • a bio-film can develop into a thick continuous coating of bacteria composed of millions of living and dead cells that build up into a layer of "slime" often compared to a coral reef.
  • the surface layer of the bio-film consists of dead cells and a mucous-like slime that absorbs nutrients but prevents conventional disinfectants like chlorine from penetrating and reaching the underlying cells.
  • bio-films can be surprisingly resistant to removal or control with chlorine and other disinfectants. Once it begins to form, a bio-film rapidly blocks membrane pores and reduces or prevents water flow through the membrane.
  • Chlorine dioxide is known to be especially useful for removing and/or controlling bio-film accumulations on water container surfaces, such as on the inside of water pipes, cooling towers and heat transfer surfaces.
  • water filtration membranes has long been warned against for a number of reasons.
  • Many membranes, such as polyamide thin film composites are quickly damaged by even small amounts of chlorine, which make chlorine disinfectants unacceptable for this application.
  • a technical manual for FilmtecTM membranes from Dow Chemical Company recommends against the use of chlorine dioxide for cleaning its membranes. Methods that involve the use of chlorine dioxide have been avoided because of the fear that the chlorine that contaminates chlorine dioxide preparations will permanently damage the membrane it is used to clean.
  • New methods of treating membranes are disclosed.
  • the methods include contacting the membranes with chlorine dioxide that does not substantially interefere with or damage filtration membrane performance during the expected lifetime of the membrane.
  • a method for treating a water filtration membrane that involves forming a chlorine dioxide stream containing a sufficient amount of chlorine dioxide to prevent the formation of, or eliminate, a bio-film on the membrane, wherein the membrane is substantially stable in the chlorine dioxide stream.
  • the chlorine dioxide can be introduced into a water feed stream that leads to the membrane.
  • the method is particularly useful when applied to filtration membranes in a water purification plant.
  • the chlorine dioxide can be formed by a step of reacting gaseous chlorine with a solid porous bed of sodium chlorite.
  • the chlorine dioxide can be introduced into the water stream of a water purification plant for limited periods of time.
  • the chlorine dioxide concentration used to treat the membrane is in the range of about 0.1 mg/L to about 2 mg/L of water.
  • the chlorine dioxide can be introduced into the water feed stream of a water purification plant at one or more locations.
  • the locations can include the raw water intake, in the raw water main between the intake and the plant, above open filter basins and/or in the feed water to filtration membrane modules.
  • the chlorine dioxide can be introduced into the water feed stream of a water purification plant at two or more locations.
  • the chlorine dioxide can be introduced into the water feed stream of a water purification plant at two or more locations and the chlorine dioxide can be introduced to each location at a different time.
  • the chlorine dioxide can be introduced directly into the flow of water in a water purification plant.
  • the chlorine dioxide can be dissolved in water which is later added to the flow of water in a water purification plant.
  • the chlorine dioxide can be continuously or intermittently introduced into the flow of water in a water purification plant.
  • a water purification plant includes the following components: a water intake, a raw water main between the intake and the plant, an open filter basin, a filtration membrane in a membrane module and a source of chlorine dioxide.
  • the chlorine dioxide source can be coupled to one or more of the water intake, raw water main between the intake and the plant, open filter basin, and membrane in a membrane module, such that chlorine dioxide can be introduced into the water flow of the plant to prevent bio-fouling of the filtration membrane.
  • the chlorine dioxide source is sufficiently pure so that the filtration membrane(s) is substantially stable to exposure to the chlorine dioxide.
  • the water purification plant contains two or more injection points for the chlorine dioxide and the plant is capable of injecting the chlorine dioxide at distinct times such that injection does not occur at more than one point at a time.
  • the delivery can be timed such that chlorine dioxide is added to basins, which are exposed to sunlight during the day, at night when it is dark.
  • Figure 1 is a diagram of a system for producing extremely pure chlorine dioxide.
  • Figure 2 illustrates a three cartridge system with breakthrough detection.
  • Figure 3 illustrates the relationship between Chlorophyll A residual and chlorine dioxide amounts in raw water in a water treatment plant after a 30 min treatment.
  • Figure 4 illustrates a conventional water treatment plant having a filtration unit.
  • Methods for treating a water filtration membrane to prevent the formation of a bio-film (bio-fouling) or remove a bio-film once it has formed are disclosed.
  • the methods involve forming a stream having a sufficient amount of chlorine dioxide to prevent the formation of a bio-film.
  • the methods can also be used to remove the film.
  • the chlorine dioxide stream is generated in a manner that avoids damage to such membranes so that the membranes are substantially stable in the chlorine dioxide stream.
  • the method can include forming an aqueous stream of chlorine dioxide and feeding that stream to the membrane and/or other components in a water treatment plant.
  • the stream can be generated by any suitable method that provides chlorine dioxide of sufficient purity to avoid membrane damage by contaminants, such as chlorine gas, that accompany many chlorine dioxide preparations.
  • Gaseous chlorine dioxide can be introduced into water that leads to the membrane.
  • the chlorine dioxide can be introduced directly into the flow of water in a plant or can be dissolved in water separately and later added to the flow in a water plant.
  • the chlorine dioxide gas can be dissolved in water by any suitable method that does not introduce contaminants or result in excessive lost gas. For example, the gas can be bubbled through the water with a sparger.
  • chlorine dioxide solutions can be prepared in packed columns with a flowing chlorine dioxide gas and counter-flowing water such that the flowing gas flows up through the column as water trickles down over the packing in the column and the dissolved chlorine dioxide solution can be collected as the aqueous effluent from the bottom of the column.
  • Suitable columns and packing can be obtained from Koch Glitsch, Inc. of Wichita, KS.
  • Many water treatment plants include filtration steps.
  • One conventional drinking water purification process shown as 200 in Figure 4, involves a source of water 210 which can be a lake, river, reservoir, aquifer or other body of water. Water from the source 210 enters an intake structure 220. Depending upon the relative elevation of the water source 210 and the treatment facility, the water then can flow by gravity or can be pumped through a raw water main 230 to a rapid mix tank 240 where chemicals 250 such as pH adjusters, coagulants and disinfectants can be added. The water can then flow through a suitable conduit 260 into flocculation and sedimentation apparatus 270 where slow mixing causes solids to coagulate and settle to the bottom of the tank where they can be removed.
  • chemicals 250 such as pH adjusters, coagulants and disinfectants
  • Coagulated solids can also be removed using other processes, such as dissolved air flotation.
  • the settled water can then flow through a suitable conduit 280 into a filter system 290, where it can be passed through beds of sand, crushed anthracite and/or other granular materials or by forcing the water under pressure through membranes. Fine suspended solids are removed by the filter medium. When the filter medium becomes filled with solid particles, it can be back washed to remove the solids, as shown by arrow 130.
  • Clean water from the filtration step can be moved by suitable conduit 300 into a finished water reservoir or storage facility 310. Water can be withdrawn from the finished water storage 310 and introduced into a distribution piping system.
  • chlorine dioxide can be introduced into the flow of a water treatment plant intermittently to prevent or eliminate bio-fouling of membranes and other water plant components.
  • the chlorine dioxide can be added for a sufficient amount of time to prevent or eliminate bio-fouling.
  • the time period for the chlorine dioxide treatment will, of course, depend to some extent upon the concentration of chlorine dioxide added to the water.
  • One of skill in the art could easily determine suitable times. For example, as shown in Figure 3, a 30 min treatment with about 1 to about 1.5 mg/L of chlorine dioxide is sufficient to eliminate virtually all of the algae from a water treatment plant. Repeated treatments can be scheduled as needed based upon the measurement of chlorophyll or other microbial loads in water flows. Increases in chlorophyll or microbial loads indicate the need for additional treatments.
  • treatment time can be used in the present methods.
  • treatments can be continuous at suitable chlorine dioxide concentrations or they can be for limited periods of time. Durations of between about 5, 10, 15, 20, 30, 45 or 60 minutes, or more, or less, and periods of time up through continuous usage can be used.
  • any suitable amount of chlorine dioxide that can prevent the formation of a bio-film can be used.
  • concentrations of chlorine dioxide ranging from about 0.1 to about 10 mg/L or more could find use in the present methods. More commonly concentrations in the range of about 0.2 to about 5 mg/L, 0.4 to about 3 mg/L, about 0.6 to about 2 mg/L, about 0.8 to about 1.5 mg/L, or about 1 to about 1.5 mg/L can be used.
  • concentrations of chlorine dioxide ranging from about 0.1 to about 10 mg/L or more could find use in the present methods. More commonly concentrations in the range of about 0.2 to about 5 mg/L, 0.4 to about 3 mg/L, about 0.6 to about 2 mg/L, about 0.8 to about 1.5 mg/L, or about 1 to about 1.5 mg/L can be used.
  • concentrations of chlorine dioxide ranging from about 0.1 to about 10 mg/L or more could find use in the present methods. More commonly concentrations in the range of about 0.2 to about 5 mg/L, 0.4 to about 3 mg/L
  • the amount of chlorine dioxide that can be added to water is generally limited by the amount of its degradation product, chlorite, that ultimately accumulates in the treated water.
  • chlorite its degradation product
  • the use of chlorine dioxide in water plants that utilize membrane filtration steps has the advantage that the membrane filter can remove a large quantity of chlorite from water.
  • certain membranes are capable of removing up to about 99% of the chlorite from water.
  • the chlorine dioxide solution can be introduced at any suitable location. Suitable locations include locations that are either near or upstream from where the chlorine dioxide solution can exert its beneficial effects.
  • chlorine dioxide can be introduced at the raw water intake, at one or more locations along the raw water main between the intake and the plant, on top of open filter basins, or in the feed water to filtration membrane modules. In a method chlorine dioxide can be introduced into the water stream at a single location.
  • chlorine dioxide can be introduced at a point near the raw water intake from whence it can flow through the intake pipes, the basins where algae control is required, and on through the membrane modules to achieve all of the benefits from a single dose.
  • the chlorine dioxide can be introduced into the water stream at multiple locations.
  • dosing at multiple locations can be problematic because chlorine dioxide forms chlorite ion when it reacts in water. This can be a problem because there are safety limits on chlorite ion concentrations in drinking water and in water discharged into the environment. Thus, high levels of chlorite caused by multiple injections might not be permissible.
  • the dosing can be scheduled in a manner that maintains chlorite concentrations at safe levels. This would allow for maintenance of various parts of a plant at different times. It is within the skill of one having skill in the art to maintain chlorite levels at or below any chosen level using standard chlorite measuring techniques.
  • membrane filtration steps can be used to remove chlorite ions from water and can be used to reduce chlorite ions from water before its release for drinking or back into the environment.
  • Chlorine dioxide can be prepared by any method that produces a product that can prevent or eliminate bio-fouling and in which the membrane is substantially stable.
  • a membrane is considered to be substantially stable when the treatment can be carried out to prevent or eliminate bio- fouling without substantial degradation in its performance (caused by chlorine dioxide treatment) during the normal or nearly normal (within about 10%) lifetime of the membrane.
  • FIG. 1 provides a diagrammatic view of one embodiment of a chlorine dioxide generation system that can be used to generate suitable chlorine dioxide for membrane and water plant treatment.
  • the system contains a source of chlorine gas (10) and air (30).
  • the chlorine gas is passed through a passageway (20), such as a pipe, and the air is passed through a passageway (40), such as a pipe, to a mixing point (50) where they are mixed, preferably, in controlled amounts.
  • the gas mixture is then passed into a reaction chamber (60) that contains solid sodium chlorite and the chlorine gas is contacted with sodium chlorite, which can be in the form of SAF-T-CHLOR® as produced by CDG Technologies, Inc.
  • the chlorine gas reacts with the sodium chlorite on contact to generate chlorine dioxide gas according to the reaction shown in Figure 1.
  • the generator can be equipped with two reaction chambers of sodium chlorite, preferably in the form of a porous solid.
  • a mixture of air and chlorine can flow through the first reaction chamber and then through the second.
  • both drums are substantially unused, substantially all of the chlorine reacts in the first cartridge according to the equation shown in Figure 1.
  • the resulting air/chlorine dioxide mixture can then flow unaffected through the second cartridge and then through an exit tube (90) where it can be introduced into a water stream in a mixer (100).
  • the mixer can contain a water feed line (70) and an exit line (80) through which the chlorine dioxide/water mixture can exit.
  • chlorine begins to break through, at first in trace amounts, but in gradually increasing concentrations as production continues.
  • the chlorine that breaks through the first cartridge is then converted to chlorine dioxide in the second cartridge.
  • the first cartridge When the first cartridge is completely spent, it can be replaced with a new cartridge, and the direction of flow through the cartridges can be, preferably, reversed so that the fresh cartridge becomes the second cartridge and the partially spent cartridge becomes the first.
  • the system is preferably configured with a system for measuring consumption of sodium chlorite in the reaction vessels.
  • a system for measuring consumption of sodium chlorite in the reaction vessels can be as simple as a scale.
  • the sodium chlorite is converted into the lighter sodium chloride which is retained in the chamber.
  • the chamber loses weight.
  • reaction chambers can be placed on scales and their weight loss monitored to determine when the sodium chlorite is virtually all consumed. Since sodium chlorite is expensive, it is preferable to fully utilize the contents of a cartridge.
  • U.S. Patent 6,537,821 describes an alternative device and process for detecting small amounts of chlorine gas in a mixture containing higher concentrations of chlorine dioxide.
  • Devices of this nature are available from CDG Technology, Inc. of Bethlehem, PA. Such devices inject a small amount of ammonia vapor into a sample stream. Ammonia reacts with chlorine but not with chlorine dioxide. When ammonia reacts with gaseous chlorine, it forms a white ammonium chloride cloud, indicating that chlorine is present. The smoke can be detected visually or can be sensed by its interference with a light signal.
  • Such a device can be used to identify chlorine as it breaks through a sodium chlorite cartridge and can produce a signal that either sounds an alarm or shuts down the system before filtration membranes are damaged by the chlorine.
  • Figure 2 illustrates a process having added assurance that chlorine will not break through the system. For simplicity, this does not show the control system and interlocks.
  • cartridges are operated in series with a breakthrough detector between cartridge 2 and cartridge 3. The detection of the first traces of chlorine provides an indication that cartridges 1 and 2 are depleted. Meanwhile, cartridge 3 provides backup so that no chlorine can pass through the system to the membrane.
  • cartridge 1 can be removed and cartridge 2 is preferably moved to the number 1 position, so that it can be completely consumed with subsequent use.
  • Cartridge 3 can be moved to the number 2 position, and a new cartridge placed in the number 3 position to ensure that no chlorine breaks through the system.
  • the system can run for an extended time over a two cartridge system without chlorine breakthrough. This allows for intermittent manual checking to make sure that the breakthrough analyzer is functioning properly. This same arrangement can be used with 3, 4 or more cartridges to maximize the time between change out.
  • Chlorine dioxide treatment provides for control of mollusks and control of algae in open basins. Since chlorine dioxide rapidly decomposes in sunlight, the addition of chlorine dioxide to open basins can preferably be carried out at night. With respect to membrane filtration, the chlorine dioxide can be used to prevent or remove bio-film and the chlorine dioxide that permeates the membrane can be used to disinfect water and conduits in the product stream.
  • HAA5s include monochloroacetic acid (MCAA), dichloroacetic acid (DCAA), trichloroacetic acid (TCAA), monobromoacetic acid (MBAA) and dibromoacetic acid (DBAA) all of which are hazardous.
  • MCAA monochloroacetic acid
  • DCAA dichloroacetic acid
  • TCAA trichloroacetic acid
  • MBAA monobromoacetic acid
  • DBAA dibromoacetic acid
  • Chlorine dioxide is known to be a highly effective means for controlling and removing mollusks such as zebra mussels and Asiatic clams that foul intakes and obstruct screens in water plants and other water processes. Chlorine dioxide injected into the raw water intake of a plant can serve to control mollusks on intake piping and then be carried through to remove bio-fouling from the pretreatment process and the membranes. Intermittent dosing at low doses for brief periods can be effective. Published reports from the American Water Works Association (AWWA) show that a dose of chlorine dioxide of as little as 0.5 ppm for 15 min four times a day can effectively control zebra mussels.
  • AWWA American Water Works Association
  • Chlorine dioxide can also be used to control algae that often grows in basins that are open to sunlight.
  • Figure 3 shows that chlorine dioxide applied for brief periods at typical doses used for disinfection can effectively destroy algae as measured by chlorophyll residual.
  • the first column of Figure 3 shows the amount of chlorophyll detected in a water stream from a water treatment plant (42 ⁇ g/L).
  • the second column shows the amount of chlorophyll detected drops to 1.8 ⁇ g/L when the water treatment plant is treated with 1 mg/L of chlorine dioxide for 30 min.
  • Column 3 shows that when the treatment was with 1.5 mg/L of chlorine dioxide the chlorophyll level was undetectable after a 30 min treatment.

Abstract

L'invention concerne un procédé destiné à traiter une membrane de filtration d'eau et consistant à former un flux de dioxyde de chlore contenant une quantité de dioxyde de chlore suffisante pour empêcher la formation d'un biofilm sur la membrane ou pour éliminer un biofilm de la surface de la membrane, ladite membrane étant sensiblement stable dans le flux de dioxyde de chlore. Le dioxyde de chlore peut être introduit dans un flux d'alimentation en eau dirigé vers la membrane. Ce procédé trouve une utilité particulière lorsqu'il est appliqué à des membranes de filtration dans une station de traitement d'eau.
PCT/US2007/076500 2006-08-22 2007-08-22 Procédé et appareil destinés à l'utilisation de dioxyde de chlore pour prévenir la biosalissure de membranes utilisées dans le traitement de l'eau WO2008024828A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US82321806P 2006-08-22 2006-08-22
US60/823,218 2006-08-22

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Publication Number Publication Date
WO2008024828A1 WO2008024828A1 (fr) 2008-02-28
WO2008024828A9 true WO2008024828A9 (fr) 2008-04-10

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10046990B2 (en) * 2011-06-06 2018-08-14 Ecolab Usa Inc. Electrolytic method of generating chloride dioxide with improved theoretical yield

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6716354B2 (en) * 2001-03-08 2004-04-06 Cdg Technology, Inc. Methods of treating water using combinations of chlorine dioxide, chlorine and ammonia
US6824756B2 (en) * 2002-05-17 2004-11-30 Cdg Technology, Inc. Process for manufacturing and using a more stable formulation of sodium chlorite
US20050061741A1 (en) * 2003-09-23 2005-03-24 Mainz Eric L. Method for treating reverse osmosis membranes with chlorine dioxide

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