Impeller-equipped water purification reactor

Abstract

A method and an apparatus for removing one or more contaminants from water are described. The method comprising introducing water with a contaminant into an apparatus comprising a mixer positioned in the vessel, where the mixer can have one or more impellers fixedly attached to a shaft. In some embodiments, a plurality of impellers includes a first impeller which is spaced from an adjacent impeller by a distance D 1 . The position of each impeller in the plurality defines a region Rn of the internal volume, where n may correspond to a number of impellers in the plurality. The vessel comprises a gas inlet for introducing ozone into the water, where the gas inlet is positioned in region Rn.

Description

IMPELLER-EQUIPPED WATER PURIFICATION REACTORCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 658,231, filed June 10, 2024, which is incorporated by reference herein.TECHNICAL FIELD

[0002] The subject matter described herein relates to methods for mitigating or degrading contaminants in water. In embodiments, the present disclosure relates to a method for degrading contaminants, such as 1,4-dioxane in water.BACKGROUND

[0003] Contaminants in ground water and industrial wastewater, such as 1 ,4-dioxane and other contaminants, have increasingly come under scrutiny by regulatory agencies, such as the U.S. Environmental Protection Agency (EP A). Legislation requires that many manufacturers of consumer products, including suppliers of bottled water, meet prescribed contaminant limits. As a result, manufacturers of raw materials used in the manufacture of consumer products are under increasing pressure to remove such contaminants generated during manufacture of the raw materials.

[0004] Chemical oxidation methods employing ozone and peroxide have been used to degrade contaminants in ground water. However, contaminated ground water may have concentrations of dioxane on the order of milligrams per liter. For example, the concentration of dioxane in wastewater from production of alkyl ether sulfates (AES) can be up to 1000 mg / L with a total organic carbon content (TOC) level of 500 ppm.

[0005] In view of the above challenges, there is an urgent need for a simple, cost-effective, and easily operated apparatus for reducing or eliminating contaminants from various water sources, including ground water, wastewater, surface water, and drinking water.

[0006] Further, in wastewater streams, there is a need for inhibiting the release of contaminants into the environment is inhibited and rendering the resulting product water suitable for other uses. There is also an urgent need for a method for reducing dioxane in wastewater streams that can achieve a high dioxane degradation rate, such as at least 98%, yet is simple, cost-effective, and easily operated.

[0007] The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.BRIEF SUMMARY

[0008] The following aspects and embodiments thereof described and illustrated below are meant to be exemplary and illustrative, not limiting in scope.

[0009] In one aspect, an apparatus is provided for increased mass transfer of ozone into water.

[0010] In one aspect, a method for removing a contaminant from water is provided. In one embodiment, the method includes the steps of introducing a water comprising a contaminant into an apparatus disclosed herein such that the contaminated water flows into each region Rn of the internal volume; initiating movement of the mixer; introducing ozone into one or more of the regions Rn to create ozone-treated water in each region; and mixing for a period of time. In another embodiment, the method includes the steps of introducing a water comprising a contaminant into an apparatus described herein; initiating movement of the mixer; introducing ozone into the water in each of the plurality of mixing regions at an ozone to water ratio of greater than 1 : 1 (v / v) to create ozone-treated water in each region; and mixing the ozone and the water for a period of time sufficient to remove the one or more contaminants from the water.

[0011] In another aspect, an apparatus is provided for increasing mass transfer of ozone into water according to the methods disclosed herein. In one embodiment, the apparatus comprises a vessel, a mixer, and a gas inlet. The vessel comprises an opening and a housing that defines an internal volume. The mixer is disposed in the internal volume, comprises one or more impellers fixedly attached to a shaft extending through the opening, and comprises a gas inlet positioned in a region Rn of the internal volume. In some embodiments, a plurality of impellers includes a first impeller which is spaced from an adjacent impeller by a distance Di. The position of each impeller in the plurality defines a region Rn of the internal volume, where n may correspond to a number of impellers in the plurality. In some embodiments, at least one impeller is positioned in each mixing region.

[0012] In another embodiment, the apparatus comprises: a vessel comprising a housing that defines an internal volume; a mixer comprising a plurality of impellers fixedly attached to a shaft through an opening; and a plurality of gas inlets. The housing includes an opening with a mixer extending therethrough. The plurality of impellers form an impeller arrangement in the internal volume. At least one impeller is positioned in each mixing region, wherein each mixing region includes at least one gas inlet. In some embodiments, the apparatus may be further characterized by an impeller arrangement defined by the types of impellers, number of impellers, position of each impeller on the shaft, and tip speed of the impellers.

[0013] In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following descriptions.

[0014] Additional embodiments of the present apparatus, methods, and the like, will be apparent from the following description, drawings, examples, and claims. As can be appreciated from the foregoing and following description, each and every feature described herein, and each and every combination of two or more of such features, is included within the scope of the present disclosure provided that the features included in such a combination are not mutually inconsistent. In addition, any feature or combination of features may be specifically excluded from any embodiment of the present disclosure. Additional aspects and advantages of the present disclosure are set forth in the following description and claims, particularly when considered in conjunction with the accompanying examples and drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a cross-sectional view of an apparatus according to the present disclosure.

[0016] FIG. 2 shows the reduction in chemical oxygen demand (COD) (in milligrams of carbon per liter of water) as a function of the total amount of ozone applied to the reactor (“Dose”) or the amount of ozone reacted in the reactor (“Actual Dose”) at a constant rate (0.5 gallons per minute (gpm) or 1.0 gpm) over time.

[0017] FIG. 3 shows the reduction in COD as a function of ozone dose introduced into the reactor with different impeller configurations

[0018] FIG. 4 shows the change in COD as a function of ozone dose introduced into the reactor at a constant rate over time.

[0019] FIG. 5 shows the reduction in TOC percentage as a function of ozone dose introduced into the reactor at a constant rate over time.

[0020] FIG. 6 shows the destruction of 1 ,4-dioxane as a function of ozone introduced into the reactor at a constant rate over time.DETAILED DESCRIPTIONI. Definitions

[0021] Various aspects now will be described more fully hereinafter. Such aspects may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art.

[0022] Where a range of values is provided, it is intended that each intervening value between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the disclosure. For example, if a range of 1 pg to 8 pg is stated, it is intended that 2 pg, 3 pg, 4 pg, 5 pg, 6 pg, and 7 pg are also explicitly disclosed, as well as the range of values greater than or equal to 1 pg and the range of values less than or equal to 8 Fg-

[0023] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a "polymer" includes a single polymer as well as two or more of the same or different polymers, reference to an "excipient" includes a single excipient as well as two or more of the same or different excipients, and the like.

[0024] The word "about" when immediately preceding a numerical value means a range of plus or minus 10% of that value, e.g., "about 50" means 45 to 55, "about 25,000" means 22,500 to 27,500, etc., unless the context of the disclosure indicates otherwise, or is inconsistent with such an interpretation. For example, in a list of numerical values such as "about 49, about 50, about 55, "about 50" means a range extending to less than half the interval(s) between the preceding and subsequent values, e.g., more than 49.5 to less than 52.5. Furthermore, the phrases "less than about" a value or "greater than about" a value should be understood in view of the definition of the term "about" provided herein.

[0025] The compositions of the present disclosure can comprise, consist essentially of, or consist of, the components disclosed.

[0026] By reserving the right to proviso out or exclude any individual members of any such group, including any sub-ranges or combinations of sub-ranges within the group, that can be claimed according to a range or in any similar manner, less than the full measure of this disclosure can be claimed for any reason.

[0027] Throughout this disclosure, various patents, patent applications and publications are referenced. The disclosures of these patents, patent applications and publications in their entireties are incorporated into this disclosure by reference in order to more fully describe the state of the art as known to those skilled therein as of the date of this disclosure. This disclosure will govern in the instance that there is any inconsistency between the patents, patent applications and publications cited and this disclosure.

[0028] For convenience, certain terms employed in the specification, examples and claims are collected here. Unless defined otherwise, all technical and scientific terms used in thisdisclosure have the same meanings as commonly understood by one of ordinary skill in the art to which this disclosure belongs.II. Stirred Reactor Apparatus

[0029] Chemical oxidation methods employing ozone and peroxide have been used to degrade contaminants in ground water. High mass transfer rates of ozone into water would greatly benefit oxidative degradation of the contaminants. Currently, the best water treatment technology for achieving high mass transfer rates of ozone into water employ static mixers with a high pressure drop. However, this technology is limited by pressures of the water and ozone sources and the amount of gas that can be added to the mixer, where the ozone : water ratio (v / v) is generally < 0.5 : 1, respectively. For increased mass transfer, a maximum ozone : water ratio (v / v) of 1 : 1 can be used or else ozone will not dissolve.

[0030] The present disclosure is based on providing a series of impellers mounted on a single shaft in an atmospheric (low pressure) vessel where the impellers are operated at high tip speeds to increase the efficiency of mass transfer of ozone into water. Such a configuration allows for the utilization of low pressure ozone and the handling of very high ozone : water ratios (greater than 1: 1) to facilitate high mass transfer (>95%) ozone in discrete sections of the vessel. Moreover, bromate formation is controlled by rapid dissolution of ozone and its oxidative reactions in water.

[0031] In one aspect, a stirred reactor apparatus is provided. In an embodiment exemplified in FIG. 1, the apparatus 10 comprises a vessel 14, a mixer 18, and one or more gas inlets 22. The vessel 14 comprises a housing 32 that defines an internal volume and an opening 26 receiving the contaminated water. The housing 32 is generally cylindrical or rectangular with a height and a radius or width and is defined by a central axis along its height, whereby the shaft is positioned parallel to the central axis.

[0032] The mixer 18 is disposed in the internal volume and comprises one or more impellers 34 fixedly attached to a shaft 38 extending through the top of a frame 16 surrounding the vessel 14 and through a rotating seal 29 on the top of the vessel 14. One end of the shaft 38 is attached to an agitator motor 30 for rotating the mixer 18, which is connected to an electrical power source 31. The agitator motor 30 and is disposed on the frame 16 and attached to the shaft 38 by a coupling. The other end of the shaft 38 is supported by a foot bearing 40 attached to the bottom of the vessel 14 for steadying the shaft 38. The water flows through one or more inlets (e. ., 26, 27) into one or more mixing regions 20 in the internal volume. The mixing regions, Rl, R2, and R3 are depicted as 20a, 20b, and 20c. In some embodiments, each mixing region Rn comprises one or more distal gas inlets 24a, 24b, and 24c for introducing gas from aproximal gas inlet 22 into the mixing regions 20a, 20b, and 20c. The vessel 14 includes a baffle 47 with slots 49 to reduce gas from spouting up the baffle 47. The vessel 14 further comprises an inlet 27 for receiving contaminated water from a feed tank 28. In some embodiments, the mixer 18 comprises a plurality of impellers 34, including a first impeller 34a which is spaced from an adjacent impeller 34b by a distance Di. The position of each impeller 34 in the plurality defines a region Rn of the internal volume, where n may correspond to a number of impellers 34 in the plurality.

[0033] The one or more impeller(s) 34 are utilized for mixing the chemical reactants with the water and moving the water in the reactor 10. The impellers 34 increase pressure and flow of the water outward in the mixing regions 20a, 20b, 20c and creating shear forces that decrease bubble size. In some embodiments, each a mixing region 18 comprises an impeller 34. In some embodiments, the reactor 10 may contain one, two, three, or four impellers, or any range thereof. Exemplary impellers 34 may be semi-enclosed or elliptical. The embodiment in FIG. 1 depicts a vessel 14 with three adjacent mixing regions, Rl, R2, and R3 depicted as 20a, 20b, and 20c, each containing a single impeller 34.

[0034] Each impeller 34 has a discrete diameter. In reactors having a circular cross-section, the impeller diameters may range from e.g., 0. 15 to 0.9 times the reactor diameter, 0.2 to 0.8 times the diameter of the reactor, or 0.3 to 0.5 times the diameter of the reactor. Generally, each impeller 34 has a plurality of blades 58. In one embodiment, the plurality of blades 58 in an impeller 34 are positioned for radial fluid flow. In another embodiment, the plurality of blades 58 in an impeller 34 are positioned for axial fluid flow. The impellers 34 may have a variable number of blades, which may vary between e.g., 2 to 12 blades, 4 to 10 blades, 4 to 8 blades. In some embodiments, an impeller may have 2 blades, 4 blades, 6 blades, or 8 blades. In some embodiments, an impeller may have a concave blade, a flat blade, an asymmetric blade, or an asymmetric concave blade.

[0035] In the vessel 14 of the present disclosure, adjacent mixing regions 20a, 20b, and 20c may be separated by one or more disks 50 directing the flow of gases and liquids e.g., water, H2O2) therethrough via disk openings 54a, 54b between the shaft 38 and disks 50a, 50b as shown in FIG. 1. In one embodiment, the number of disks 50 is less by one of the numbers of impellers 34. In FIG. 1, each of the three adjacent regions, Rl, R2, and R3 contains a single impeller, 34a, 34b, and 34c, wherein adjacent regions R1-R2 are separated by a first disk 50a and adjacent regions R2-R3 are separated by a second disk 50b. As shown in FIG. 1, each region Rn of the internal volume is in fluid communication via one or more openings 54a, 50b in the disks 50a, 50b that are adjacent to the shaft 38.

[0036] The housing 32 may comprise an upper surface 62, a lower surface 66, and side wall 70, and several inlets for receiving water, an oxidizing agent, such as hydrogen peroxide, and / or a gas, such as ozone, into the vessel 14. These fluids may be pumped into the mixing regions 20a, 20b, 20c through one or more inlets positioned on the upper surface 62, a lower surface 66, and side wall 70 of the vessel 14. For example, as shown in FIG. 1, water can be pumped from a feed tank 28 through a water inlet 27 into the mixing regions 20a, 20b, 20c of the vessel 14 . In one embodiment, the water may be pumped to flow up through an inlet 26 near the bottom of the vessel 14 and into the mixing regions 20a, 20b, 20c via the disk openings 54a, 54b between the shaft 38 and the disks 50a, 50b adjacent thereto. Alternatively, the water may be pumped to flow down through an openings 27 near the top of the vessel 14 into the mixing regions 20a, 20b, 20c and through the disk openings 54a, 54b.

[0037] The vessel 14 may further include a liquid inlet 74 in fluid communication with another liquid, such as hydrogen peroxide and / or a pH adjustment agent from a liquid supply source 82. In some embodiments, the hydrogen peroxide and / or pH adjustment agents may be introduced into each Rn region (or chamber / mixing region) via multiple liquid inlets 78a, 78b, and 78c. In an exemplary embodiment depicted in FIG. 1 , hydrogen peroxide can be pumped from a hydrogen peroxide supply source 82 into the vessel 14 through a liquid inlet 74 into each Rn region via liquid inlets 78a, 78b, and 78c. In certain embodiments, the hydrogen peroxide may be introduced in an upper or lower Rn region, or from above or below the vessel 14 with the feed stream of water prior to its introduction into the vessel 14.

[0038] In some embodiments, gases, such as ozone, may be pumped into the mixer 18 from an ozone supply source 42 via a manifold 46 through an opening 22 into the mixing regions 20a, 20b, and 20c via gas inlets 24a, 24b, and 24b. The vessel 14 may further comprise a gas removal outlet 55. In some embodiments, the number of gas inlets 24 is equal to the number of impellers 34. In other embodiments, the number of gas inlets 24 is less by one of the number of impellers 34.

[0039] In one embodiment, the apparatus 10 comprises a radial impeller 34 for moving water in a direction generally perpendicular to the axis of the shaft 38. In one embodiment, the radial impeller 34 is a Bakker impeller. In certain embodiments, the radial impeller is a six-bladed Bakker turbine (BT-6) gas dispersion impeller (Chemineer Inc.). In another embodiment, the apparatus 10 comprises an axial impeller 34 for moving water in a direction generally parallel to the axis of the shaft 38. In another embodiment, the apparatus 10 comprises both radial and axial impeller(s) 34. The radial and axial impellers 34 may be in different Rn regions or they may both be in the same Rn region. In one embodiment, the apparatus 10 comprises two radialimpellers 34 in one or more of the same Rn regions. In another embodiment, the apparatus 10 comprises an axial impeller 34 above a radial impeller 34 in one or more of the same Rn regions. In another embodiment, the apparatus 10 does not comprise an axial impeller 34 above a radial impeller 34 in any of the mixing regions 20a, 20b, 20c.

[0040] In certain embodiments, one of two impellers 34 in the same Rn region are placed one impeller diameter from the bottom of the Rn region and another impeller 34 is placed one impeller diameter above the other impeller or one impeller diameter below the top of the Rn region. In certain embodiments, as exemplified in FIG. 1, each impeller 34 is placed in or near the middle (center) of each Rn region, whereby the diameter of the impeller 34 above and below defines a natural separation of the liquid. In another embodiment, an impeller 34c may be placed one impeller diameter from the bottom of the reactor 10 in mixer region 20c, while the other impeller(s) (e.g., 20a and 20b) are placed one impeller diameter above the preceding impellers (e.g., 20b and 20c, respectively).II. Method for Removing Contaminants from Water

[0041] In another aspect, a method for removing one or more contaminants from water is provided. The method may be carried out using any apparatus described above. In one embodiment, the method includes the steps of introducing water comprising a contaminant into an apparatus 10, where the apparatus comprises a vessel 14 comprising a housing 32 that defines an internal volume and an opening in the housing 32; a mixer 18 comprising one or more impellers 34 fixedly attached to a shaft 38; and a gas inlet 22 positioned in a region Rn of the internal volume. The contaminated water is introduced so that it flows into each region Rn of the internal volume. The method further comprises the steps of initiating movement of the mixer 18; and introducing ozone into one or more of the regions Rn to create ozone-treated water in each region; and mixing for a period of time. The ozone is used to reduce the content of oxidizable chemicals, especially the oxidizable contaminants described herein.

[0042] In another embodiment, the method includes the step of introducing water comprising a contaminant into an apparatus 10 comprising a vessel 14, where the vessel 14 comprises a housing 32 that defines an internal volume; a mixer 18 comprising a plurality of impellers 34 fixedly attached to a shaft 38; a gas inlet 22 for receiving s gas, such as ozone from an ozone supply source 42; and a plurality of gas inlets 78a, 78b, and 78c for introducing the gas into a corresponding mixing region 20a, 20b, and 20c. The housing 32 includes frame 16 with the mixer 18 extending therethrough and connectively linked to an agitator motor 30 for rotating the mixer 18. The plurality of impellers 34 form an impeller arrangement in the internal volume, where each impeller 34 is positioned in a mixing region 20 in a region Rn of theinternal volume, which further includes at least one gas inlet 24. The method further comprises the steps of initiating movement of the mixer 18; introducing ozone into the water in each of the plurality of mixing regions 20 at an ozone to water ratio of greater than 1 : 1 (v / v) to create ozone-treated water in each region; and mixing the ozone and the water for a period of time sufficient to remove the one or more contaminants from the water.

[0043] Apparatus 10 utilized in the methods disclosed herein may be further characterized by an impeller arrangement defined by the types of impellers, number of impellers, position of each impeller on the shaft, and tip speed of the impellers. In some embodiments, the impellers are operated at a tip speed of greater than 10 revolutions per second. In certain embodiments, the impellers are operated at a tip speed between 15 revolutions per second and 20 revolutions per second. In some embodiments, the impellers are placed about 0.5 to 2.0, 0.75 to 1.5, or about one impeller diameter above the bottom of a mixing region or the base of the shaft 38.

[0044] As described above, the apparatus 10 utilizes one or more radial and / or axial impeller(s) 34 described herein for mixing the oxidizable contaminants with the water and moving the water in a direction generally perpendicular or generally parallel to the shaft’s 38 axis in the apparatus 10. It is believed that when the ozone dose is applied or increased to a point approaching the maximum in a mixing region 20a containing an impeller 34a, a second impeller 34b in an adjacent mixing region 20b improves the efficiency and amount of ozone introduced into reactor vessel 14 by sequential mixing from e.g., one mixing region 20a to another mixing region 20b below. The increased efficiency from multiple mixer zones directly impacts, and reduces, chemical oxygen demand (COD) and total organic carbon (TOC) values in the water.

[0045] In some embodiments, the method further comprises determining concentration of the contaminant in ozone-treated water in one or more of the regions after mixing. In an embodiment, the contaminant in the water introduced into the apparatus is at a concentration which is above regulatory limits. In an embodiment, the contaminants are oxidizable chemicals such as 1,4-dioxane, trichloroethylene (TCE), n-nitrosodimethylamine (NDMA) methyl tertiary butyl ether (MTBE), nonylphenol (NP), triclosan (TCS), bisphenol-A (BPA), an endocrine disrupting compound (EDC), an estradiol equivalent (EEQ), a pharmaceutically active compound (PhaC), and / or a pathogen. In an embodiment, the introduced water is ground water, wastewater, surface water, or drinking water or manufacturing waste.

[0046] In an embodiment, the level of 1 ,4-dioxane is reduced from a range of between about 10 ppm to about 1000 ppm to less than about 5 ppb, less than about 2 ppb, less than about 1 ppb, less than about 0.5 ppb of 1,4-dioxane after treatment, or to a less than between about 0.1-5 ppm,. 0.1-2 ppb, or 0.1-1 ppb. Alternatively, the level of 1,4-dioxane may be reduced to a concentration after treatment of no more about 0.3 ppb, about 0.5 ppb, about 1 ppb, about 2 ppb, about 5 ppb, or any range of these values.

[0047] In an embodiment, the formation of bromate in the treated water is less than about 10 ppb, less than about 5 ppb, less than about 1 ppb, or any range thereof. In an embodiment, the method further comprises removing the ozone-treated water from the apparatus 10 if the concentration of the contaminant is determined to be environmentally safe for discharge or for use, or is below a limit of detection.

[0048] The apparatus described herein may be used to reduce chemical oxygen demand (COD) and total organic carbon (TOC) in a water source. As used herein, COD is used with reference to a measurement of the oxygen required to oxidize soluble and particulate organic matter in water. TOC is used herein with reference to the amount of carbon found in water. In some embodiments, a COD test may be conducted to provide a measurement of the mass of oxygen needed to consume all oxidizable chemicals per volume of solution (typically in mg / L) as a function of ozone dose. In some embodiments, a TOC test may be conducted to measure the amount of organic carbons needed to be oxidized or having been oxidized per volume of solution (typically in mg / L) as a function of ozone dose.

[0049] When treating the water introduced into the apparatus with ozone, the COD and TOC concentrations decrease as a function of ozone dose introduced into the apparatus. In some embodiments, the COD of water (e.g., waste water) introduced into the apparatus is between about 100 mg / L and 5,000 mg / L, between about 200 mg / L and 2,000 mg / L, between about 500 mg / L and 1,500 mg / L, or any range thereof. In some embodiments, the TOC of water obtained following the treatment is between about 100 mg / L and 2,000 mg / L, between about 200 mg / L and 1 ,000 mg / L, between about 400 mg / L and 800 mg / L, or any range thereof.

[0050] In an embodiment, the ozone is introduced into the water through one or more inlets 22 in one or more of the regions Rn of the internal volume of the mixer 18 at a pressure below about 20 psig. In an embodiment, n corresponds to a number of impellers in the plurality of impellers and / or a number of mixing regions R in the internal volume. In another embodiment, the ozone is introduced into the water through one or more inlets 22 in one or more of the regions Rn of the internal volume of the mixer 18 at a pressure below about 10 psig. In another embodiment, the ozone is introduced into the water through one or more inlets 22 in one or more of the regions Rn of the internal volume of the mixer 18 at a concentration of between about 10 ppm and 500 ppm, between about 25 ppm and 400 ppm, between about 50 ppm and 200 ppm, between about 75 ppm and 170 ppm, or any range thereof. In an embodiment, theozone-treated water in the terminal region of the internal volume after mixing has a contaminant concentration between about 100 to 3,000 ppm. In some embodiments, the ozone- treated water is drinking water.

[0051] In another embodiment, hydrogen peroxide (H2O2) is introduced into the mixer 18 from an H2O2 supply 86 via a second fluid inlet 82. The second fluid inlet 82 may be positioned in the upper surface 62, the lower surface 66, or side wall 70 of the housing 32. In some embodiments, the hydrogen peroxide is injected into the feed stream of water through an opening e.g., 26 or 27. In some embodiments, the H2O2 is introduced into the vessel 14 containing the water in an amount of about 0.8 to 4 molar equivalents of H2O2 to ozone. In some embodiments, the hydrogen peroxide may be introduced with an acid salt, such as NaHCO3, NaHS, NaHSO4, NaH2PO4or Na2HPO4.

[0052] Alternatively, or in addition, the hydrogen peroxide may be introduced with an inorganic acid compound, such as HC1, H2SC , HNO3, H3PCU, HF, HC1O4, H3BO3, HBr, or HI.III. Examples

[0053] The following examples are illustrative in nature and are in no way intended to be limiting.EXAMPLE 1OZONE DOSE VS. COD

[0054] A pilot reactor with dimensions of 6 inches by 20 inches was constructed with a single 3” radial impeller in a single mixing region near the bottom of the shaft. The reactor was tested to evaluate decreases in chemical oxygen demand (COD) (in milligrams of carbon per liter of water) as a function of increasing ozone concentrations. Contaminated water was provided using municipal water and adding a contaminant as a marker for the test, along with 250 mg / L blue dye #2. Flow gas: 2.9 L / min - 5.7 L / min; Volume: 4 liters; Water flow: 0.5 gpm and 1.0 gpm.

[0055] The results of this analysis are shown in Table 1 and FIG. 2. In Table 1 and FIG. 2, the “Actual Dose” reflects unreacted ozone measured in the vent being removed from the calculation while the “Dose” is based on the total amount of ozone applied. The results show that the introduction of increasing ozone doses at two different feed flows of water resulted in concomitant decreases in chemical oxygen demand (COD) (in milligrams of carbon per liter of water).Table 1EXAMPLE 2COD REDUCTION AS A FUNCTION OF IMPELLER VARIATION

[0056] Pilot reactors with dimensions of 6 inches by 20 inches were constructed. Each reactor had a different impeller arrangement. The first arrangement utilized a reactor as described in Example 1. The two impeller arrangements utilized a first impeller spaced one impeller diameter from the bottom and a second impeller spaced one impeller diameter above the first impeller. The contaminated water was provided using Pittsburg city water and adding a contaminant, along with 250 mg / L blue dye #2. Flow gas: 1.0 L / min - 5.0 L / min; Volume: 4 liters.

[0057] The results of this analysis are shown in Table 2 and FIG. 3 and illustrate that a number of different impeller arrangements in this system can effectively promote contaminant removal from water.Table 2EXAMPLE 3COD REDUCTION AS A FUNCTION OF OZONE DOSE IN THE PRESENCE OF OZONE AND NAHCOS

[0058] A pilot reactor with dimensions of 6 inches by 20 inches was constructed with the impeller configuration depicted in FIG. 1. Contaminated water was provided using municipal water and contaminant was added, along with 250 mg / L blue dye #2 and 68 gms NaHCOs for adjusting pH to optimize the reaction rate of ozone and hydrogen peroxide in water at steady state conditions. Flow gas: 1.0 L / min - 5.0 L / min; Volume: 4 liters. Hydrogen peroxide was added to the water before treatment with ozone in batch mode.

[0059] The results of this analysis are shown in Table 3 and FIG. 4.Table 3EXAMPLE 4REDUCTION IN TOTAL ORGANIC CARBON (TOC)

[0060] A study was carried out using a stirred pilot reactor with dimensions of 6 inches by 20 inches was constructed with the impeller configuration depicted in FIG. 1. An advanced oxidation process plug-flow reactor (HiPOx®) with static mixers and a stirred reactor of the present disclosure (referred to as HiPOx XL) were evaluated for their ability to reduce total organic carbon (TOC). The reactors were run in three different modes: HiPOx Batch, HiPOx XL Batch, and HiPOx XL Continuous. The HiPOx Batch was run using an existing lab HiPOx plug-flow reactor. HiPOx Batch and HiPOx XL Batch are batch tests. In a batch reactor test, water fills the reactor and ozone and hydrogen peroxide is applied to the batch water for the reaction to take place. After a fixed amount of ozone and hydrogen peroxide have been applied, the treatment is completed, the treated water batch is emptied. XL Cont. is a continuous reactor with water, ozone, and hydrogen peroxide continuously applied to the reactor at a specified dose (mg / L) and the reactor product continuously removed. In a continuous reactor operation, the water flows continuously in the reactor and the dose of ozone and hydrogen peroxide reactants are fed into the reactor continuously and the treated water is removed from the reactor as product.

[0061] The results of this test are shown in FIG. 5. The results show that the batch processes were quicker and more effective in TOC reduction compared to the continuous process and that the HiPOx XL stirred reactor was more effective in TOC reduction compared to the HiPOx plug-flow flow reactor.EXAMPLE 5DESTRUCTION OF 1,4-DIOXANE

[0062] The pilot reactor in Example 4 was evaluated for its ability to destroy 1 ,4-dioxane. The test was run in both batch and continuous modes as described in Example 4. The results of this test are shown in FIG. 6. The results show that the batch processes were quicker and more effective in destroying 1 ,4-dioxane compared to the continuous process and that the HiPOx XL stirred reactor was more effective in TOC reduction compared to the plug-HiPOx plug-flow flow reactor.EXAMPLE 6REDUCED BROMATE FORMATION UPON INTRODUCTION OF OZONE AND HYDROGEN PEROXIDE

[0063] Ozonation is known to produce an undesired side reaction in oxidizing bromide ions (Br“) in water to intermediate brominated species, i.e., hypobromite (OBr-) and hypobromiteradical, and eventually to bromate (BrCh ), a suspected carcinogen. The U.S. EPA Stage I Disinfectants / Disinfection By-Products rule sets a limit of 10 pg / L for bromate.

[0064] The effect of introducing ozone and hydrogen peroxide on bromate formation was evaluated in stirred reactors having two different impeller configurations similar to the design in FIG. 1. Both tests were run in batch mode.

[0065] One test was run specifically to determine bromate formation response using a water that had excessive bromate formation with standard advance oxidation treatment. The test was run with a single radial impeller (3” radius). As shown in Table 4, ozone and hydrogen peroxide were introduced to the reactor at 25 mg / L ozone and 50 mg / L hydrogen peroxide. The starting bromide concentration was 1400 pg / L and 7.7 pg / L of bromate was formed. This represented a bromate conversion rate of 0.55%. The results further showed that the low ozone conditions of this test produced significant reductions in bromate formation.Table 4

[0066] Another test was run on water contaminated with trichloroethylene (TCE), n- nitrosodimethylamine (NDMA) and 1,4-dioxane. The water also contained 1200 pg / L of bromide, ozone and hydrogen peroxide were applied to a stirred reactor containing two radial impellers (3” radius). The test was run with two radial impellers. As shown in Table 5, ozone and hydrogen peroxide were applied to the reactor at 90 mg / L ozone and 89 mg / L hydrogen peroxide. The starting bromide concentration was 1200 pg / L and 1.8 pg / L of bromate was formed. This represented a bromate conversion rate of 0.15%.Table 5

[0067] The amount of bromate formed during the tests were significantly less than similar tests conducted with ozone, hydrogen peroxide and water with static mixers on the same water as shown in Table 6. The use of static mixers to contact water, ozone, and hydrogen peroxide is a common practice.Table 6

[0068] While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions, and subcombinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions, and sub-combinations as are within their true spirit and scope.

Claims

IT IS CLAIMED:

1. A method for removing one or more contaminants from water, comprising: introducing a water comprising a contaminant into an apparatus comprising a vessel, a mixer, a gas inlet, and a mixing region, wherein the vessel comprises a housing that defines an internal volume; wherein the mixer comprises one or more impellers fixedly attached to an impeller shaft, which is connected to a motor for rotating the mixer; and wherein the gas inlet is positioned in a region Rn of the internal volume; initiating movement of the mixer; introducing ozone into the water in the mixing region at an ozone to water ratio of greater than 1 to 1 (v / v) to create ozone-treated water in the mixing region; and mixing the ozone and the water for a period of time sufficient to remove the one or more contaminants from the water.

2. The method of claim 1 , wherein the contaminated water flows into a plurality of mixing regions in the internal volume; wherein the mixer extends through an opening positioned in the upper surface of the housing and the mixer comprises a plurality of impellers forming an impeller arrangement in the internal volume, wherein the vessel comprises a plurality of gas inlets, wherein each mixing region comprises at least one gas inlet; wherein one or more impellers are positioned in each mixing region, and wherein the impeller arrangement is defined by impeller type(s), number of impellers, position of each impeller on the shaft, and tip speed of the impellers.

3. The method of claim of claim 1 or 2, wherein the water is from ground water, waste water, surface water, drinking water, or manufacturing waste.

4. The method of any one of claims 1-3, wherein the ozone is introduced into the water of each mixing region at a gas to water ratio between 1.5 to 1 and 5 to 1 (v / v).

5. The method of any one of claims 1-4, wherein the position of each impeller defines a mixing region Rn of the internal volume.

6. The method of any one of claims 1-5, wherein a first impeller is spaced from an adjacent impeller by a distance Di where n corresponds to a number of impellers in the plurality of impellers and / or a number of mixing regions in the mixer.

7. The method of any one of claims 1-6, wherein the one or impellers comprise a plurality of impellers.

8. The method of claim 7, wherein the plurality of impellers comprises at least one radial impeller.

9. The method of claim 7, wherein the plurality of impellers comprises at least one axial impeller.

10. The method of claim 7, wherein the plurality of impellers comprises a combination of radial impellers and axial impellers.1 1 . The method of any one of claims 2-10, wherein one or more mixing regions comprises two or more impellers.

12. The method of claim 11, wherein the mixer comprises three impellers, wherein a single impeller is disposed in each of three mixing regions.

13. The method of claim 12, wherein each of the three impellers is a radial impeller.

14. The method of any one of claims 1-13, wherein each impeller has a plurality of blades.

15. The method of claim 14, wherein each impeller has six blades.

16. The method of any one of claim 1-15, wherein the vessel does not comprise any mixing region with an axial impeller positioned above a radial impeller.

17. The method of any one of claims 1-16, wherein the shaft extends through an opening in the disk.

18. The method of any one of claims 2-17, wherein adjacent mixing regions are separated by the disk and each mixing region is in fluid communication with one another via an opening between the disk and the shaft.

19. The method of claim 18, wherein a number of disks in the vessel is one less than the number of impellers n in the plurality of impellers.

20. The method of any one of claims 1-19, wherein one or more gas inlets are in fluid communication with an ozone supply.

21. The method of any one of claims 1-20, wherein one or more gas inlets are in fluid connection with a manifold that is operably connected to an ozone supply.

22. The method of any one of claim 1-21, wherein one or more gas inlets are positioned below an impeller.

23. The method of any one of claim 1-21, wherein one or more gas inlets are positioned above an impeller.

24. The method of any one of claim 1-23, wherein the housing comprises an upper surface, a lower surface, and a side wall, and the opening positioned in the upper surface.

25. The method of claim 24, wherein the housing further comprises a liquid inlet for a feed stream of water, optionally wherein hydrogen peroxide is injected into the feed stream of water.

26. The method of claim 25, wherein the liquid inlet is positioned in the lower surface, the upper surface, or the side wall.

27. The method of claim 25 or claim 26, comprising a second liquid inlet.

28. The method of claim 27, wherein the second liquid inlet is in fluid communication with a source of hydrogen peroxide29. The method of any one of claim 1-28, wherein the housing is cylindrical with a height and a radius or rectangular with a height, width, and length.

30. The method of claim 29, wherein the cylindrical or rectangular housing has a central axis along its height, and the shaft is positioned parallel to the central axis.

31. The method of claim 29, wherein the cylindrical or rectangular housing has a central axis along its height, and the shaft is positioned along the central axis.

32. The method of any one of claims 29-31, comprising a cylindrical housing wherein each impeller in the plurality of impellers has a diameter, and the diameter of each impeller is about 0.3 to 0.5 times the diameter of the housing.

33. The method of any one of claims 1-32, wherein the one or more impellers are operated at a tip speed of greater than 10 revolutions per second.

34. The method of claim 33, wherein the impellers are operated at a tip speed between 15 revolutions per second and 20 revolutions per second.

35. The method of any one of claims 1-34, wherein the ozone is introduced into the water at a pressure below 20 psig.

36. The method of claim 35, wherein the ozone is introduced into the water at a pressure below 10 psig37. The method of any one of claims 1-36, wherein the ozone is introduced into the water of each mixing region at a concentration of between 10 to 500 ppm.

38. The method of any one of claims 1 -37, wherein the water introduced into the vessel comprises a chemical oxygen demand (COD) between 100 to 5,000 mg / L.

39. The method of any one of claims 1-37, wherein the water introduced into the vessel comprises a total organic carbon (TOC) content between 100 to 2,000 mg / L.

40. The method of any one of claims 1-39, wherein the one or more contaminants in the water are selected from the group consisting of 1,4-dioxane, bromate, trichloroethylene (TCE), n- nitrosodimethylamine (NDMA) methyl tertiary butyl ether (MTBE), nonylphenol (NP), triclosan (TCS), Bisphenol-A (BPA), an endocrine disrupting compound (EDC), an estradiol equivalent (EEQ), a pharmaceutically active compound (PhaC), a pathogen, or a combination thereof.

41. The method of claim 40, wherein the impeller arrangement is sufficient to produce a reduction in COD and / or TOC of at least 95% or 99%.

42. The method of any one of claims 1-41, further comprising after said mixing, performing a COD or TOC test of the ozone-treated water in one or more mixing regions.

43. The method of any one of claims 1-41, further comprising after said mixing, determining a concentration of a contaminant in ozone-treated water in one or more of the mixing regions.

44. The method of claim 43, wherein the contaminant is bromate and the concentration of bromate after said mixing is determined to be less than about 10 ppb.

45. The method of claim 43, wherein the contaminant is 1,4-dioxane and the concentration of1,4-dioxane after said mixing is determined to be less than 1 ppb.

46. The method of any one of claims 1-45, further comprising removing the ozone-treated water from the apparatus if the concentration of at least one contaminant is determined to be environmentally safe for discharge or for use, or is below a limit of detection.

47. The method of claim 46, wherein the at least one contaminant is bromate and wherein the ozone-treated water is removed from the apparatus if bromate is present in the ozone- treated water at a concentration less than about 10 ppb.

48. The method of claim 46 or claim 47, wherein the at least one contaminant is 1 ,4-dioxane and wherein the ozone-treated water is removed from the apparatus if 1,4-dioxane is determined to have a concentration less than about 5 ppb.

49. An apparatus, comprising: a vessel comprising a housing that defines an internal volume, the housing comprising an opening; a mixer comprising one or more impellers fixedly attached to a shaft; and a gas inlet positioned in a region Rn of the internal volume.

50. The apparatus of claim 49, wherein: the internal volume comprises plurality of mixing regions and a plurality of gas inlets, wherein each mixing region comprises a gas inlet positioned in a region Rn of the internal volume the mixer is disposed in the internal volume and comprises a plurality of impellers fixedly attached to the shaft through the opening, and at least one impeller is positioned in each mixing region, wherein the internal volume comprises an impeller arrangement, and the impeller arrangement is defined by types of the impellers, number of the impellers, placement of the impellers, and tip speed of the impellers.

51. The apparatus of claim 49 or claim 50, wherein the mixer is disposed in the internal volume with the shaft extending through an opening, wherein a first impeller is spaced from an adjacent impeller by a distance Di and the position of each impeller in the plurality of impellers defines a region Rn of the internal volume, where n corresponds to a number of impellers in the plurality of impellers and / or a number of mixing regions in the internal volume.

52. The apparatus of any one of claims 49-51, wherein the plurality of impellers comprises at least one radial impeller.

53. The apparatus of any one of claims 49-51 , wherein the plurality of impellers comprises at least one axial impeller.

54. The apparatus of any one of claims 49-53, wherein the plurality of impellers comprises a combination of radial impellers and axial impellers.

55. The apparatus of any one of claims 49-54, wherein one or more mixing regions comprises two or more impellers.

56. The apparatus of any one of claims 49-55, wherein the mixer comprises three impellers, wherein a single impeller is disposed in each of three mixing regions.

57. The apparatus of claim 56, wherein each of the three impellers is a radial impeller.

58. The apparatus of any one of claims 49-57, wherein each impeller has a plurality of blades.

59. The apparatus of claim 58, wherein each impeller has six blades.

60. The apparatus of any one of claim 49-59, wherein the internal region does not contain any mixing region comprising an axial impeller positioned above a radial impeller.

61. The apparatus of any one of claims 49-60, wherein the opening is adjacent to the shaft.

62. The apparatus of any one of claims 50-61, wherein adjacent mixing regions are separated by a disk.

63. The apparatus of claim 62, wherein a number of disks is one less than the number of impellers n in the plurality of impellers.

64. The apparatus of claim 62 or claim 63, wherein each mixing region is in fluid communication with one another via an opening in the disk.

65. The apparatus of any one of claims 49-65, wherein one or more of the gas inlets are in fluid communication with an ozone supply.

66. The apparatus of any one of claims 49-65, wherein one or more of the gas inlets are in fluid connection with a manifold that is operably connected to an ozone supply.

67. The apparatus of any one of claim 49-66, wherein one or more gas inlets are positioned below an impeller.

68. The apparatus of any one of claim 49-66, wherein one or more gas inlets are positioned above an impeller.

69. The apparatus of any one of claim 49-69, wherein the housing comprises an upper surface, a lower surface, and a side wall, and the opening is positioned in the upper surface.

70. The apparatus of claim 69, wherein the housing further comprises a liquid inlet for a feed stream of water, optionally wherein hydrogen peroxide is injected into the feed stream of water.

71. The apparatus of claim 70, wherein the liquid inlet is positioned in the lower surface, the upper surface, or the side wall.

72. The apparatus of claim 70 or claim 71 , comprising a second liquid inlet.

73. The apparatus of claim 72, wherein the second liquid inlet is in fluid communication with a source of hydrogen peroxide .

74. The apparatus of any one of claim 49-73, wherein the housing is cylindrical with a height and a radius or rectangular with a height, width, and length.

75. The apparatus of claim 74, wherein the cylindrical or rectangular housing has a central axis along its height, and the shaft is positioned parallel to the central axis.

76. The apparatus of claim 74, wherein the cylindrical or rectangular housing has a central axis along its height, and the shaft is positioned along the central axis.

77. The apparatus of any one of claims 74-76, comprising a cylindrical housing wherein each impeller in the plurality of impellers has a diameter, and the diameter of each impeller is about 0.3 to 0.5 times the diameter of the housing.

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