WO2014066931A1 - Procédé et appareil pour le traitement d'eau - Google Patents

Procédé et appareil pour le traitement d'eau Download PDF

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Publication number
WO2014066931A1
WO2014066931A1 PCT/AU2013/001242 AU2013001242W WO2014066931A1 WO 2014066931 A1 WO2014066931 A1 WO 2014066931A1 AU 2013001242 W AU2013001242 W AU 2013001242W WO 2014066931 A1 WO2014066931 A1 WO 2014066931A1
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WO
WIPO (PCT)
Prior art keywords
water
tank
module
filtration
conditioning module
Prior art date
Application number
PCT/AU2013/001242
Other languages
English (en)
Inventor
Gheorghe Emil Duta
Original Assignee
Water Science Technologies Pty Ltd
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
Priority claimed from AU2012904778A external-priority patent/AU2012904778A0/en
Application filed by Water Science Technologies Pty Ltd filed Critical Water Science Technologies Pty Ltd
Priority to CN201380057647.1A priority Critical patent/CN104936904B/zh
Priority to AU2013337588A priority patent/AU2013337588B2/en
Publication of WO2014066931A1 publication Critical patent/WO2014066931A1/fr
Priority to HK16101964.2A priority patent/HK1213869A1/zh

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Classifications

    • 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
    • C02F1/725—Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
    • 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
    • C02F1/727—Treatment of water, waste water, or sewage by oxidation using pure oxygen or oxygen rich gas
    • 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
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
    • C02F1/56—Macromolecular compounds
    • 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
    • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
    • 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
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/20—Heavy metals or heavy metal compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/03—Pressure
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/40—Liquid flow rate
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/42—Liquid level
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2305/00—Use of specific compounds during water treatment
    • C02F2305/02—Specific form of oxidant
    • C02F2305/023—Reactive oxygen species, singlet oxygen, OH radical

Definitions

  • This invention relates to a process and apparatus for water treatment, the water treatment including at least one catalytic oxidation step.
  • Disinfection level and standards have been adopted for drinking water treatment of wastewater for reuse.
  • Water turbidity is associated with disinfection level on the basis that suspended solids passing through the treatment system into the treated water could harbour and protect pathogens from inactivation and destruction. Potable water should be free from dangerous bacteria and viruses.
  • E. Coli count has to be less than 10 per 100 ml of water. It is thought that in such case the turbidity of the water before disinfection should be less than 2 NTU in order to achieve disinfection targets. This holds true for the use of traditional technologies for water disinfection to produce high quality water. Technologies used are a combination of membrane filtration and ozone and ultraviolet radiation, potentially expensive processes.
  • Twin mixed media filters in series can remove a high concentration of suspended solids.
  • the arrangement in which each filter is backwashed with the feed water to that particular filter and sized to operate at constant flow rate is very economical while achieving a high degree of clarification.
  • Such filters could produce water with turbidity of less than 4 NTU. Whilst this is a good performance, the quality of the water produced is not suitable for disinfection to produce safe high quality water.
  • One more filtration stage is needed and membrane filtration is typically the additional final stage.
  • Microfiltration and ultra filtration membranes achieve the level of clarification needed before disinfection.
  • An object of the invention is to propose an energy efficient and cost effective alternative water purification process suitable for addressing aspects of water contamination and scarcity as described above.
  • the present invention provides, in a first embodiment, a process for treating water comprising the step of oxygenating water for treatment with an oxygen containing gas in a conditioning module wherein said oxygenation process is catalysed by at least one metal salt dosed into said conditioning module under oxidising and pH conditions at which reactive metal radicals and hydroxyl radicals form.
  • the present invention provides an apparatus for treating water comprising a conditioning module provided with an oxygen containing gas supply means to enable oxidation of water with an oxygen containing gas; and a metal salt dosing means for supplying at least one metal salt to said conditioning module to catalyse the water oxygenation process under oxidising and pH conditions at which reactive metal radicals and hydroxyl radicals form.
  • the oxygen containing gas may include air.
  • Oxygen may be generated by a suitable oxygen generator whether adsorption or membrane based.
  • the gas supply means is not required to deliver gas at high pressure though control over gas flowrate is advantageous.
  • the dominant source of oxidant used in accordance with this invention is the oxygen containing gas. Such gases are typically less expensive than oxidants such as hydrogen peroxide and ozone. Handling is also typically safer.
  • the Applicant has observed that the above processes do not need to be conducted at high pressures, say more than twice atmospheric pressure. Indeed, favoured operating pressures include atmospheric pressure and do not exceed 0.2 MPa. Water heating apparatus is not required either.
  • the catalytic oxygenation process described above proceeds at acceptable rate for water treatment at ambient temperature at the geographic location of the module, expected to almost always be below 50 Q C.
  • the process is therefore advantageously carried out at ambient temperature and ambient or near ambient pressure range as above favoured. This promotes safety, energy efficiency and reduction in plant capital and operating cost.
  • the metal catalysed oxidation processes described in this specification are therefore distinguished from prior pressurised oxidation processes.
  • the metal salt(s) may advantageously be selected from the group consisting of water soluble iron, aluminium and manganese salts. Chlorides and sulphates of these metals, for example ferric chloride, manganese chloride, aluminium chloride and aluminium sulphate, are particularly suitable not least because selected soluble metal salts, which are a source of reactive metal radicals in solution under oxidising conditions, are best selected for purposes of catalysing the oxygenation reaction process. Any of these metal salts could be introduced to water in the conditioning module as single salts.
  • Iron salts are a particularly advantageous example since, under oxidising conditions, highly reactive metal radicals - such as ferryl ions - may be produced following a Fenton reaction type scheme though not exactly the same since hydrogen peroxide (and other strong oxidants) and acid pH conditions are not generally required in accordance with the invention.
  • Reactive metal radicals such as ferryl and analogous radicals (such as manganyl) are most stable under neutral to alkaline conditions.
  • a plurality of metal salts selected from the above group of salts are introduced to the conditioning module in combination to optimise catalytic oxidation forming co-precipitates or floes enabling removal of toxic elements and organic compounds from the water being treated.
  • a non- limiting example of a useful combination is a combination of any two or more of ferric, manganic or aluminium chlorides.
  • Such metal salts form acidic solutions with water so requiring pH control at the conditioning module to ensure that the favourable alkaline conditions for oxidation and co-precipitation of elements (particularly heavy metals and metalloids together with iron, manganese and aluminium) are supported and maintained. Acidic conditions should or must be avoided.
  • Catalytic oxidation reactions should proceed to sufficient extent to lower elemental and organic concentrations in water to meet potable water standards.
  • introduction of such metal salts promotes Fenton like reactions which generate highly reactive radicals, such as hydroxyl and ferryl (where iron is involved) radicals with oxidation capability comparable with ozone. This maximises rate of oxygenation of the water in the conditioning module.
  • the dissolved oxygen level of water is substantially increased in the conditioning module.
  • This increase in dissolved oxygen level itself enhances the catalytic oxidation reactions within the conditioning module particularly under alkaline conditions which are generally required for water treatment according to the invention. These reactions result in substantial and efficient oxygenation necessary for metal and organic removal or decontamination without requiring strong oxidants to be introduced under most circumstances.
  • introducing said at least one metal salt, but more preferably two or more metal salts assists removal of organics and other elements through oxidation (mineralisation), co-precipitation, flocculation and/or coagulation processes, these processes themselves being driven by catalytic oxidation reactions.
  • Metal salts used in the process and apparatus of the invention, as well as most efficacious combinations of metal salts to favour mineralisation, oxidation and formation of co- precipitates and floes may be selected for their flocculant properties.
  • Ferric chloride is again a suitable example of a metal salt selected for both catalytic and flocculant properties.
  • polymer flocculants are more conveniently dosed into the conditioning module.
  • Polymer flocculants conveniently those with amphoteric properties such as those based on acrylic acid and acrylamide, are of particular value when water is highly alkaline with pH above about 9. In that pH range, conventional flocculants like alum and ferric chloride may be ineffective. Anionic or cationic flocculants could also be used.
  • the conditioning module performs other potential functions in addition to water oxygenation. Settling of a portion of the floes and precipitates is likely to occur in the conditioning module which may comprise solids removal means for removing such portion of floes and co-precipitates. As a result, water for treatment undergoes a substantial degree of clarification in the conditioning module.
  • the conditioning module desirably includes pH adjustment means for dosing acid or alkali (more typical as alkaline conditions are required) as necessary to provide a target pH, typically in the alkaline range.
  • pH correcting chemicals may advantageously include sodium hydroxide and hydrated lime. Less typically, pH correcting chemicals such as sulphuric acid and hydrochloric acid may be required. All these mentioned chemicals are relatively inexpensive reagents.
  • a disinfectant such as chlorine conveniently in the form of chlorine dioxide, to prevent bacterial growth and slime formation within the process and apparatus.
  • Additional chemicals may sometimes require to be introduced to the conditioning module.
  • Such chemicals may include common water treatment chemicals: coagulant metal salts, polymer and other flocculants, disinfectants such as sodium hypochlorite and chlorine dioxide.
  • the range of chemicals used as well as the number of chemical dosing units used varies with the overall process implementation and physico-chemical speciation of the water to be treated. That is, some reagents may only be required if speciation or nature of the water to be treated requires. For example, water with low suspended solids content might not require a complex flocculant to be introduced.
  • the process and apparatus should include a further catalytic oxidation module and a filtration module.
  • the catalytic oxidation and filtration modules could form separate, though interconnected, modules within the process and apparatus. More conveniently, the process and apparatus includes a single module which integrates the processes of oxidation and filtration. This simplifies the process flowsheet and reduces the capital and operating cost of water treatment plant operating in accordance with the above described water treatment process.
  • a catalytic oxidation and filtration module (a term which should be understood to comprehend either a single such module incorporating functions of both catalytic oxidation and filtration or separate catalytic oxidation and filtration modules for each unit operation) comprises a bed of granular material, typically in form of a fixed bed.
  • the granular material which may comprise a mixture of granular materials, is selected to provide catalytic oxidation and filtration functions. In effect, the granular material forms a catalytic filter.
  • Preferred granular materials are metal oxide catalysts, for example, and especially preferred, manganese oxide catalysts, which have the function of promoting oxidation and co-precipitation of elements with the iron, aluminium and manganese salts used in the conditioning module.
  • Such metal oxides are conveniently deposited on, that is supported, by various supports which include silica sand, garnet and zeolites.
  • Another category of catalytic granular materials is obtained by deposition of noble metals on various substrates of granules with large surface area. For example, gold or platinum may be deposited on granular carbon. Selection of granular materials may depend on the catalytic efficiency needed, that is, the degree of catalytic activity and oxidation necessary to treat a water stream with particular physical and chemical properties.
  • the particle size of the granular material should be optimised to provide surface area for promoting catalytic oxidation reactions as well as filtration capability. It is important that co-precipitates formed in the oxidation and filtration module, as well as any carryover precipitates or floes from the conditioning module are removed at this stage in the process and apparatus.
  • Bed depth and aspect ratio may be selected to achieve requisite degree of catalytic oxidation and filtration.
  • An oxidant especially a strong oxidant such as hydrogen peroxide, may be introduced - if only occasionally necessary - to the catalytic oxidation and filtration module to promote catalytic advanced oxidation and precipitation of particularly organics but also any elements still present within the water. Oxidation by any such oxidant is catalysed by the granular material catalyst as described above. Fenton and Fenton type reactions may be observed with a number of metal salts. If an iron salt is present, such reactions may proceed in accordance with the following Fenton reaction scheme illustrating generation of reactive radicals which participate in catalytic oxidation and catalytic advanced oxidation:
  • Manganese is an example.
  • the Fe can be replaced in the above scheme with Mn or M.
  • the highly reactive hydroxyl (stronger oxidant than ozone) and ferryl or other metallic radicals particularly react, in catalytic advanced oxidation to degrade or mineralise organic material.
  • organic material is degraded to carbon dioxide, salts and mineral acids.
  • Mineralisation of pathogens also results in disinfection though a disinfectant would still typically be required.
  • Such catalytic advanced oxidation is not typically necessary for removal of metals.
  • Such oxidant may also be dosed - together with any other required reagents (especially metal salt catalysts or pH correction chemicals) into the conditioning module, or the line interconnecting the conditioning module with the catalytic oxidation and filtration module, as required, potentially substituting disinfectant if not required.
  • any other required reagents especially metal salt catalysts or pH correction chemicals
  • the process and apparatus requires water transfer means to convey water from the conditioning module to the catalytic oxidation module. Although this could possibly occur by gravity, at least one pump is likely to be required for water transfer between the conditioning and catalytic oxidation modules.
  • a pump should be selected which avoids shearing of floes and co-precipitates to extent interfering with the necessary filtration to meet potable water standards of these flocs/co- precipitates from the water in the catalytic oxidation and filtration module.
  • a progressive cavity pump may be especially suitable.
  • Water from the conditioning module is advantageously pumped at controlled rate through the catalytic oxidation and filtration module. This allows more efficient catalytic oxidation and filtration.
  • conditioning or catalytic oxidation and filtration modules may perform unit operations other than as above described.
  • the conditioning module may be configured to conduct water softening.
  • Raw water for treatment in the process and apparatus may be from primary sources such as groundwater or water already processed through a primary treatment for removal of large solids, oils and fats and heavy petroleum hydrocarbons for which specialized equipment known to those skilled in the art is used for these purposes.
  • the raw water may contain high levels of heavy metals.
  • product potable water is available for supply to users. Such water may be stored in a product water storage vessel.
  • Each of the conditioning and catalytic oxidation and filtration modules require unit operations to be conducted in vessels, typically tanks, comprised within each module. As few tanks as possible should be used to reduce costs.
  • the conditioning module comprises a plurality of vessels or tanks, one tank may be subjected to aeration (with air or other gas) and a second tank to oxygenation (with oxygen or oxygen enriched gas) to enable more complex treatment schemes.
  • the catalytic oxidation and filtration module may comprise a plurality of vessels or tanks for applications where there is a high suspended solids content in the raw water (or as a result of catalytic oxidation).
  • a first filter tank may include a filter bed only performing filtration, a second or subsequent tank also performing catalytic oxidation.
  • all tanks in the catalytic oxidation and filtration module may perform both catalytic oxidation and filtration.
  • Granular material may have different resolution (that is, particle size distribution, mean particle size) between the tanks. If two or more tanks are used, the first tank may have a filter bed having coarser resolution than granular material used in the second and any subsequent tanks.
  • a modular construction approach may be adopted for the water treatment apparatus of the invention with additional vessels being added either in series or parallel as water treatment capacity is scaled up.
  • the Applicant's research shows that treatment of water to potable standard is possible using one or two vessels though this will depend on treatment capacity and the rate at which metal salts and other reagents are dosed into the conditioning module, in particular.
  • the fewer the vessels used for a given water treatment capacity, the more cost effective will be a water treatment plant constructed and operated in accordance with the process and apparatus of the invention.
  • the vessels may provide for recirculation either to themselves or to another tank whether in the same or different module. That is, the vessels may be operated in batch or continuous mode.
  • Tank level may be monitored and treatment processes implemented dependent on tank level, some processes being conducted only when a tank is substantially full.
  • Tank(s) used in the conditioning module may be provided with an overflow arrangement for directing water to the catalytic oxidation and filtration module.
  • Conditioning tank(s) may be enclosed, for reasons of hygiene, though this is not mandatory as would be the case if pressurisation for pressure oxidation was required.
  • Tank(s) used in the catalytic oxidation and filtration modules are enclosed and typically enclose a headspace above the catalytic filter bed.
  • a distributor may be included to distribute water over the surface of the catalytic filter bed to minimise prospect of channelling or voidage.
  • the process and apparatus are not expected to be suitable for desalination operations, that is for removal of soluble salts if present) in water to be treated.
  • Desalination involves, for example, removal of chlorides; especially sodium chloride from briny water, often the only permanent water source in some remote regions.
  • desalination of water may be conducted downstream of the conditioning and catalytic oxidation and filtration modules.
  • Membrane processes are most likely to be suitable for desalination applications. As regards desalination and other possible downstream contaminant removal processes, particularly ion exchange, such processes are likely to be made more economical and efficient by producing well clarified water, free from heavy metals and organics in the prior conditioning and catalytic oxidation and filtration modules.
  • the conditioning and filtration module should be subjected to backwashing at regular intervals to prevent clogging of the catalytic filter bed with precipitates and other contaminants.
  • water for backwashing the filters is typically stored in a separate tank.
  • Dedicated pump and plumbing are also required.
  • For pressure filtration a common solution is to use three or more filters and backwash one filter at a time by directing the water exiting the other filters in reverse through the bed of the filter to be backwashed. Such plant is made relatively compact through avoiding water storage for backwash.
  • many filter units and valves are likely to be required.
  • the process and apparatus of the present invention does not require either water storage or complex filter unit/valve/pump arrangements for backwashing. Precipitates and other solids may be separated by any convenient means. It may also be convenient and cost effective to recycle backwash water to the conditioning module or even raw water storage.
  • the process and apparatus conveniently switches to batch mode with raw water supply being shut off. Water from the conditioning module is then pumped through the catalytic oxidation and filtration module and returned to the conditioning module in a closed loop. When the water is of quality suitable for backwashing then backwashing is performed. Backwashing water does not have to be of the same quality as final product water.
  • Switching the plant to batch mode processing could also be useful in case of serious deterioration of raw water quality due to natural disasters causing floods or accidental contamination from human economic activities.
  • water exiting the catalytic oxidation module would preferably be directed to product water storage instead of directing it to that tank in the conditioning module.
  • the capacity of the plant is lower than in continuous mode, the duration of individual processes is flexible and the plant could handle much higher level of water contamination than in continuous mode.
  • Fine particles could escape from time to time from the catalytic filter bed and a fine filter may be included, if necessary, to retain such particles, preventing entrainment in the potable water produced by the process and apparatus of the invention and directed to users or storage as product water.
  • the process and apparatus of the present invention is applicable for treatment of water from primary sources such as groundwater, treatment of wastewater for reuse or safe disposal and treatment of water for remediation of contaminated sites.
  • the process is especially applicable to heavy metal contaminated water and treatment of acid mine drainage water which requires to be treated to reduce dissolved metals and acidity.
  • Fig. I is a process diagram of a water treatment apparatus constructed and, operated in accordance with one embodiment of the present invention.
  • Fig. 2 is a process diagram of a water treatment apparatus constructed and operated in accordance with another embodiment of the present invention.
  • Fig. 3 is a process diagram of water treatment apparatus constructed and operated in accordance with another embodiment of the present invention.
  • Tank 10 is provided with level switches to detect full condition so that the flow of incoming raw water could be stopped, preventing overflow, and a low limit for initiating fill up and receiving raw water.
  • Another level switch might be used to detect tank empty condition and prevent the transfer pump 20 from running dry.
  • the transfer pump 20 is controlled using a variable speed drive so that in conjunction with flow transmitter 300 the water flow rate could be programmed, monitored and corrected.
  • In line strainer 40 has the purpose of retaining large solids contained in raw water; it may be isolated for cleaning by closing manual valve 30 either when clogging occurs or during routine maintenance aimed at avoiding clogging. Clogging level of strainer 40 is detected by the control system through the increase in speed of transfer pump 20 required to maintain a given flow in order to overcome obstruction of water passage by debris accumulated in the strainer 40.
  • Transfer pump 20 delivers the water to vessel 120, here a tank, in the conditioning module 1 00 at a continuous controlled rate (though it may be noted that the process could be operated in batch mode).
  • Water level in tank 120 is monitored by ultrasonic level transmitter 80 and maintained close to full level by adjusting the speed of main pump 180 where necessary to maintain the level. This is done to maximise efficiency of the process and output of product water likely to be subject to high user demand.
  • Tank 120 is provided with a filter breather 90 to prevent potential contamination from air entering tank 20 when the level of water decreases as happens during backwash operation or batch operating mode.
  • the dosing unit 50 doses a metal salt, such as ferric chloride into the water for treatment.
  • a metal salt such as ferric chloride
  • ferric chloride solution as dosed, will be acidic with pH about 2.
  • More than one metal salt dosing unit may be used for dosing a combination of metal salts (especially iron, aluminium and manganese salts) into the water.
  • a plurality of dosing units and injection points for the metal salts and any other reagents may be located on the incoming raw water line 25 to introduce these metal salts.
  • the primary role of the metal salts is to provide a source of reactive metal radicals to catalyse oxygenation of the water to increase dissolved oxygen level and drive co-precipitation and flocculation processes which facilitate removal of contaminant elements and organics from the water to be treated.
  • metal catalysed oxidation may directly remove contaminants from the water through an oxidation process which volatilises or mineralises the contaminant, often an organic contaminant, away from the liquid or aqueous phase. Where pathogens are mineralised, disinfectant requirements may be reduced since the oxidation process itself has a disinfecting effect.
  • pH tends to decrease from the moderately alkaline range where reactive metal radical and hydroxyl radicals most optimally progress oxygenation towards neutral level, partly as a result of chemical species formed by the oxidation reactions and partly due to introduction of acidic metal salt solutions, for example ferric chloride solution.
  • pH may fall from the range of 9- 1 1 to about 7 to 8. pH decrease is a function of contamination of the water. A relatively clean water may only undergo a pH adjustment of about 0.5. A more contaminated water may undergo a pH adjustment of a few pH units.
  • Conditioning tank 120 includes a dosing unit 50, of conventional type for use in water treatment plants, for adding pH correcting chemicals which may most advantageously be selected from the following: sulphuric acid, hydrochloric acid, sodium hydroxide and hydrated lime, relatively inexpensive reagents.
  • pH correcting chemicals which may most advantageously be selected from the following: sulphuric acid, hydrochloric acid, sodium hydroxide and hydrated lime, relatively inexpensive reagents.
  • Required pH range may be achieved by suitable control unit such as a SCADA, DCS or other control unit supervising the operations of water treatment plant 700.
  • Disinfectant such as sodium hypochlorite
  • conditioning tank 120 for local plant disinfection and also to provide a residual as is the case of drinking water to be distributed through a pipe network.
  • Disinfectant dosing unit 70 is also of typical construction and is used for dosing sodium hypochlorite. Dosing of disinfectant may depend on pathogen concentration, e. g E coli count in the water to be treated.
  • the dosing unit 70 may dose hydrogen peroxide, where very occasionally necessary, to further promote catalytic advanced oxidation for destruction of organics through mineralisation processes caused by reaction of highly reactive hydroxyl and ferryl radicals with the organics as above described.
  • Preferred point of injection of hydrogen peroxide is just before the filter reactor for implementation of catalytic advanced oxidation.
  • Addition of hydrogen peroxide generates Fenton reactions, as above described, to generate the hydroxyl and ferry radicals. Other reactive metallic radicals may also be generated in Fenton type reactions. Destruction of organics also has a disinfectant effect and may reduce disinfectant reagent consumption.
  • a key component of the conditioning module A is the oxygen generator 100 which supplies oxygen gas, diffused into the water through fine bubble diffuser 1 10, into conditioning tank 120.
  • the oxygen generator 100 is preferably of pressure swing adsorption type using a zeolite bed; it produces oxygen of purity close to 90% for use in water treatment plant 700.
  • the dissolved oxygen level of water is therefore substantially and deliberately increased in conditioning tank 120 by oxygen diffusion.
  • This increase in dissolved oxygen level itself drives the catalytic oxidation reactions within the conditioning module. These reactions result in substantial and efficient oxygenation and co-precipitation, flocculation and/or coagulation processes for contaminant removal, as above described, these processes themselves being driven by catalytic oxidation reactions.
  • conditioning tank 120 also allows thorough mixing of water and reagents within that tank 120. This increases process efficiency in an energy efficient manner.
  • Some high density particles may be present in the water from time to time and metal oxide and hydroxide floes may settle in part, together with high density particles at the bottom of the tank 120. Removal of high density particles is important to avoid contamination of filtration and catalytic oxidation beds and potential jamming or damage to the motorized valves. Valve 1 60 is opened intermittently, if required, to discharge matter settled at the bottom of tank 120. However, it is not always critical that flocculated material be removed through settling and discharge from tank 120. Retention of flocculated material may also, or even more conveniently, take place in the filtration and catalytic oxidation beds.
  • Catalytic oxidation beds retain flocculated matter in the upper side of the bed.
  • the suction connection for the main pump 1 80 is located above the bottom of tank 1 20.
  • the bottom side of tank 120 is shaped so that precipitated matter slides down the side walls and settles, concentrating at the bottom for discharge. Most often the bottom of tank 120 is of conical shape with internal angle of cone of 60 degrees or less.
  • Manual valve 170 is used for isolating the tank 120, preventing water leakage, if the main pump 180 has to be serviced or other components downstream from the valves 170 have to be dismantled.
  • the main pump 180 is preferably of progressive cavity type run through a variable speed drive. This type of pump delivers smooth flow, without pulses and does not shear floes formed through coagulation-flocculation during catalytic oxidation processes. Sweeping floes can form without addition of specific flocculent polymer.
  • the pressure rating of the pump used is less than 300 kPa. All the components in the water treatment plant 700 on the pressure side of the pump have higher pressure rating. Thus, the pressure relief valve 190 is used only to protect the pump 180.
  • the chemicals dosing unit 200 is used for dosing a flocculant polymer into water transferring from conditioning module A to catalytic oxidation and filtration module B.
  • the flocculant polymer may be an amphoteric polymer flocculant based on acrylic acid and acrylamide and available from Itochu Chemicals. Such polymer flocculant is efficient at the moderately alkaline pH (above 9) where other flocculants such as alum and ferric chloride are ineffective.
  • Mixing and aggregation of floes takes place in the pipes and components along the line before the catalytic filter tank 240 of catalytic oxidation and filtration module B and in the headspace above the catalytic filter bed inside the catalytic filter tank 240.
  • This catalytic filter bed is fixed and water is distributed over the surface of the bed by a suitable distributor.
  • Tank 240 is purposefully not pressurised to degree required for pressure oxidation.
  • the catalytic filter bed of tank 240 comprises granular material selected to provide catalytic and filtration functions.
  • the granular material forms a catalytic filter.
  • Preferred granular materials are metal oxide catalysts which have the function of promoting oxidation and co- precipitation of elements with the iron, aluminium and manganese salts used in the conditioning module. Such metal oxides are conveniently deposited on, that is supported, by various supports which include silica sand, garnet and zeolites.
  • Manganese oxide catalyst materials including supported manganese oxide catalysts are suitable and preferred.
  • Manganese greensand has a zeolite base or support on which manganese oxide is deposited.
  • DM1 65 material available from Quantum Filtration Pty Ltd has manganese oxide attached to a substrate of silica sand. These materials, and others, could be used alone or in combination.
  • the granular material may be selected with reference to the required degree of catalytic oxidation in catalytic oxidation and filtration module B.
  • the particle size of the granular material within the catalytic filter bed is optimised to provide surface area for promoting catalytic oxidation reactions as well as filtration capability. It is important that co-precipitates formed in the oxidation and filtration module B, as well as any carryover precipitates or floes from the conditioning module A are removed at this stage in the water treatment plant 700.
  • Bed depth and aspect ratio may be selected to achieve requisite degree of catalytic oxidation and filtration.
  • Instruments 210 and 260 are pressure indicators, pressure gauges showing total system pressure and respectively pressure downstream from catalytic oxidation and filtration module B (and catalytic filter tank 240). At the same time pressure indicator 260 will show a pressure increase with the increase in clogging level of in line fine filter 280 for polishing any small particulate material remaining in the water at this stage.
  • Pressure transmitter 220 measures total system pressure on pressure side of main pump 180.
  • Pressure transmitter 250 measures pressure downstream from catalytic oxidation module B. The pressure difference is used to trigger backwashing of the catalytic filter tank 240 bed.
  • Backwashing may be triggered based on set time interval or initiated manually if needed.
  • the three way motorized valves 230 are of type typically used for pressurized sand filters and mixed media filters and operating modes of the catalytic oxidation filters are the same:
  • Rinse mode whereby the water travels through the catalytic filter bed within tank 240 the same way as in normal mode except that valve 270 directs the water back to tank 120 in the water conditioning module.
  • Rinse mode is used to clear suspended solids which could settle in the lower part of the bed following the backwash and bed settling.
  • line filter 280 is used to retain breakage which may escape from time to time form the catalytic filter tank 240 bed.
  • Filtration resolution particle size as measured by mean particle size
  • For surface water one micron resolution is recommended to provide an additional barrier for Cryptosporidium oocysts.
  • Treated water is stored for use or downstream processing (such as desalination using membranes or ion exchange) in the product or clean water tank 290. This water may be used directly from tank 290 or may be re-chlorinated and pumped through a pipe network for distribution as may be the case with potable water.
  • raw water is received into tank 10 and is pumped at controlled flow rate to the conditioning tank 120 of conditioning module A by transfer pump 10.
  • Water is treated in the conditioning module A with chemicals, including metal salts and any additional chemicals as above described, and oxygenated in preparation for filtration and catalytic oxidation in module B.
  • Main pump 180 follows incoming flow so that water level in tank 1 20 is maintained close to full level.
  • Main pump 180 pumps the water through the catalytic filter bed, in catalytic filter tank 240, then through the valve 270, in line filter 280 and into treated water tank 290.
  • water treatment plant 700 When water treatment plant 700 operates in batch mode, and any other mode related to backwash, the supply of water from raw water tank 10 to downstream modules A and B of water treatment plant 700 is interrupted until one batch of water has been treated; or backwash and rinse mode are completed.
  • batch mode when tank 120 is confirmed full, pump 20 stops.
  • water is then oxygenated (as above described) and disinfectant is dosed during final part of oxygenation when the water in tank 120 is thoroughly mixed.
  • main pump 180 starts and water is processed through catalytic oxidation and filtration module B in the same manner as described above for continuous mode.
  • level transmitter 80 If low tank 120 level is detected by level transmitter 80, the process stops, pump 20 starts and water is pumped to the conditioning module until tank 120 is full and the process continues with treatment of the new batch of water.
  • the second embodiment of the apparatus operated in accordance with the process and apparatus of the invention shows a water treatment plant with two tanks 1 20 in the conditioning module A.
  • This arrangement allows for more complex conditioning treatment when the plant is operated in continuous mode.
  • An important modification, when comparing with the plant shown in Fig 1 is that the first tank 120A is provided with aeration (with air) instead of oxygenation (with oxygen from oxygen generator 100).
  • Aeration means 310 could be a diaphragm air pump or blower. Aeration provides air stripping, oxidation and chemicals mixing with the water.
  • the chemical dosing unit 320 may be used for dosing a second metal salt as would be the case when removing cadmium by dosing manganese chloride in addition to iron chloride or sulphate.
  • Dosing the metal salts in the first tank 120A increases the amount of dissolved metals, in this case iron and manganese in the water.
  • Metal salts in solution creating highly acidic solutions decrease the pH of the water so pH control to maintain moderately alkaline conditions, favouring both combined oxidation (with hydroxyl and reactive metal radicals) and element co-precipitation, is required.
  • While water treatment plant 700 is running in continuous mode, dosing sodium hydroxide in the same tank would not favour dissolution of iron and manganese. Co-precipitation starts in the second tank 120B when pH increases through addition of sodium hydroxide. Some other processes might be implemented by diffusing oxygen in both tanks 120A, 120B or by diffusing another gas, other than air, in the first tank 120A.
  • the lower part of first tank 120 is connected through a launder to upper part of the second tank I 20 so that water flows by gravity from first tank into the second tank.
  • Water level monitoring is also set up for the second tank 120B.
  • water is directed through the additional or first tank 120A provided with aeration until the second tank 1 20B, provided with oxygenation, is full.
  • FIG. 3 there is shown a third embodiment in which water treatment plant 700 comprises two filter tanks 240 and 245 in the catalytic oxidation module B.
  • This arrangement allows for more complex treatment in the catalytic oxidation module B.
  • the additional filter tank 245 is placed before catalytic filter tank 240.
  • Such construction may be suitable for handling a large volume of suspended solids without the need to use a further dedicated clarifier.
  • the filter tank 245 could be loaded with a mixed media bed, which though of manganese oxide as above described is of coarser filtration resolution (i. e particle size distribution) than the resolution for the bed of catalytic filter 240.
  • the mean particle size of granular material in the bed of filter tank 245 is about two times larger than the size of granular material in filter tank 240.
  • the Applicant's tests find this particle size to be optimum for operating two filter beds in series with at least the second filter tank 240 holding a catalytic oxidation filter bed.
  • the first bed located in filter tank 245 could be also of catalytic type when targeting a finer degree of removal of particular contaminants through catalytic oxidation.
  • the water treatment plant of Fig. 3 is also configured for chemical water softening.
  • the pH of the water could be raised in the conditioning module A.
  • the tank 120 could be run with solid particles in suspension to provide seeding for precipitation of water hardness (in the form of calcium and magnesium salts at least). As the particles grow larger, they settle to the bottom of the tank 120 and are intermittently discharged through valve 160. Suspended solids, fine particles and metal hydroxide and oxide precipitates could be filtered for removal from water by the bed in filter tank 245. Until the water exits tank 245, the pH will be maintained high or moderately alkaline to promote oxygenation through activity of the highly reactive metal and hydroxyl radicals.
  • Polymer flocculant such as the amphoteric polymer flocculant described above, dosed through dosing unit 200 supports flocculation at high pH.
  • acid e. g sulphuric acid
  • chemical dosing unit 55 to lower pH.
  • Metal salts for catalytic oxidation are dosed through chemical dosing unit 50 and sodium hypochlorite disinfectant is dosed through chemical dosing unit 70.
  • Dosing sodium hypochlorite at high pH is not effective for disinfection.
  • chlorine dioxide may be dosed intermittently into incoming raw water before tank(s) 120, 120A, 120B in the conditioning module A.
  • additional pressure indicator 2.5 and pressure transmitter 225 measure the pressure downstream from first filter tank 245. Thus individual pressure drop on each of the two filter tanks can be monitored.
  • Backwash can be triggered when any of the two filter tanks 240, 245 reaches a maximum set pressure drop. If the water treatment plant 700 is configured to include chemical water softening, the water is prepared first for backwashing the granular bed of filter tank 245, just in tank 120 without running it through downstream filter 280. Time has to be allowed for settling, and then the sludge is drained, through bottom valve 160, from the bottom of tank 120. Suitable water for backwashing filter 245 can be achieved although this water is not required to be as clean as product water. After backwashing filter 235, this filter 235 is set in normal mode, rinsing for this filter is not needed.
  • water is treated through both filters 240 and 245.
  • Water exiting filter 240 is directed by valve 270 back to the tank 1 20 in closed loop.
  • the pH of water has to be maintained at the same level before catalytic filter 240 as when operating the water treatment plant 700 in normal mode.
  • filter 245 operating in normal mode. Adjustment of pH is not needed and acid dosing is not performed. Only dosing of disinfectant is used for this mode.
  • Batch mode operation of plant shown in Fig. 3 is the same as described above for the plant in Fig. 1 except that for the plant in Fig. 3, water has to pass through the two filter tanks 240 and 245 and then is directed to clean water tank 290 by valve 270.

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Treatment Of Water By Oxidation Or Reduction (AREA)

Abstract

L'invention porte sur un procédé pour le traitement d'eau comprenant l'étape d'oxygénation de l'eau pour traitement avec un gaz contenant de l'oxygène dans un module de conditionnement, ledit procédé d'oxygénation étant catalysé par au moins un sel métallique ajouté de façon dosée dans ledit module de conditionnement dans des conditions d'oxydation et de pH auxquelles des radicaux métalliques réactifs et des radicaux hydroxyle se forment. Le procédé d'oxygénation ne nécessite pas l'utilisation de peroxyde d'hydrogène ou d'ozone et peut être mis en œuvre à température et pression ambiantes. L'invention porte également sur un appareil (700) pour mettre en œuvre le procédé.
PCT/AU2013/001242 2012-11-01 2013-10-28 Procédé et appareil pour le traitement d'eau WO2014066931A1 (fr)

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CN201380057647.1A CN104936904B (zh) 2012-11-01 2013-10-28 用于水处理的方法和设备
AU2013337588A AU2013337588B2 (en) 2012-11-01 2013-10-28 Process and apparatus for water treatment
HK16101964.2A HK1213869A1 (zh) 2012-11-01 2016-02-23 用於水處理的方法和設備

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CN107226508A (zh) * 2017-08-01 2017-10-03 星汉阿卡索环境科技（北京）有限公司 Dmi和活性炭复合床深度净化生产饮用水的方法及装置
CN107531533A (zh) * 2015-03-16 2018-01-02 水科技有限公司 处理水的方法和设备
WO2019022947A1 (fr) * 2017-07-28 2019-01-31 Frito-Lay North America, Inc. Procédé de récupération et de traitement de l'eau de cuisson de friteuse
WO2021072483A1 (fr) * 2019-10-14 2021-04-22 Infinite Water Technologies Pty Ltd Procédé et appareil de traitement d'eau

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WO2004060834A1 (fr) * 2003-01-02 2004-07-22 Yissum Research Development Company Of The Hebrew University Of Jerusalem Production amelioree de radicaux hydroxyle
WO2007055476A1 (fr) * 2005-11-10 2007-05-18 E & Wis Co., Ltd. Systeme et procede de traitement des eaux
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Cited By (8)

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Publication number Priority date Publication date Assignee Title
CN107531533A (zh) * 2015-03-16 2018-01-02 水科技有限公司 处理水的方法和设备
US11111165B2 (en) 2015-03-16 2021-09-07 Infinite Water Technologies Pty Ltd Process and apparatus for treating water
WO2019022947A1 (fr) * 2017-07-28 2019-01-31 Frito-Lay North America, Inc. Procédé de récupération et de traitement de l'eau de cuisson de friteuse
US10519050B2 (en) 2017-07-28 2019-12-31 Frito-Lay North America, Inc. Method for fryer stack recovery and treatment
GB2578983A (en) * 2017-07-28 2020-06-03 Frito Lay North America Inc Method for fryer stack water recovery and treatment
GB2578983B (en) * 2017-07-28 2021-12-29 Frito Lay North America Inc Method for fryer stack water recovery and treatment
CN107226508A (zh) * 2017-08-01 2017-10-03 星汉阿卡索环境科技（北京）有限公司 Dmi和活性炭复合床深度净化生产饮用水的方法及装置
WO2021072483A1 (fr) * 2019-10-14 2021-04-22 Infinite Water Technologies Pty Ltd Procédé et appareil de traitement d'eau

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AU2013337588A1 (en) 2015-06-11
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CN104936904A (zh) 2015-09-23
CN104936904B (zh) 2017-05-17

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