Free radical generator and method Number:6,991,735 from the United States Patent and Trademark Office (PTO) owispatent

Title: Free radical generator and method

Abstract: An apparatus for generating free radical species can be used to sanitize water systems. The apparatus generates hydroxyl free radical species using substantially pure water, or using a liquid that is substantially free of oxygen-reactive species, to maximize free radical species generation to sanitize the water system. The free radical species are generated by ultraviolet radiation having a wavelength of less than or equal to 254 nm.

Patent Number: 6,991,735 Issued on 01/31/2006 to Martin

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Inventors:	Martin; Roy (Downers Grove, IL)
Assignee:	USFilter Corporation (Warrendale, PA)
Appl. No.:	083284
Filed:	February 26, 2002

Current U.S. Class:	210/748; 210/759; 210/763
Current Intern'l Class:	C02F 1/32     (20060101); C02F 1/72     (20060101)
Field of Search:	210/748,758,759,760,763,192,198.1,205,206 422/24,186.3 250/432.R,435,436

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References Cited [Referenced By]

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Primary Examiner: Lawrence; Frank M.
Attorney, Agent or Firm: Lowrie, Lando & Anastasi, LLP

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Claims

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What is claimed is:

1. A method of reducing oxygen demand in a water system comprising:

providing a low oxygen demand liquid to a hydroxyl free radical generator;

irradiating the low oxygen demand liquid with actinic radiation to generate hydroxyl free radicals; and

adding the low oxygen demand liquid comprising the hydroxyl free radicals to the water system,

wherein the low oxygen demand liquid is not water from the water system.

2. The method of claim 1, wherein the free radical generator comprises a channel disposed to flow the low oxygen demand liquid therethrough during irradiation with actinic radiation.

3. The method of claim 2, wherein a surface of the channel is reflective to actinic radiation.

4. The method of claim 2, wherein a wall of the channel comprises a coating capable of catalytically promoting free radical production.

5. The method of claim 4, wherein the coating comprises titanium dioxide.

6. The method of claim 2, wherein a wall of the channel comprises any of stainless steel, titanium or alloys thereof.

7. The method of claim 1, further comprising adding a hydroxyl free radical donor to the low oxygen demand liquid.

8. The method of claim 7 wherein the hydroxyl free radical donor comprises at least one of hydrogen peroxide, ozone, oxygen, and a peroxygen compound.

9. The method of claim 8, wherein the low oxygen demand liquid has at least about 0.1% active H₂O₂.

10. The method of claim 1, further comprising lowering a pH of the low oxygen demand liquid to less than about 9.

11. A method of reducing oxygen demand in a water system comprising:

providing a low oxygen demand liquid, not from the water system, to a hydroxyl free radical generator;

generating hydroxyl free radicals in the low oxygen demand liquid; and

adding the low oxygen demand liquid comprising the hydroxyl free radicals to the water system.

12. The method of claim 11, further comprising adding a hydroxyl free radical donor to the low oxygen demand liquid.

13. The method of claim 12, wherein the hydroxyl free radical donor comprises at least one of hydrogen peroxide, ozone, oxygen, and a peroxygen compound.

14. The method of claim 13, wherein the low oxygen demand liquid has at least about 0.1% active H₂O₂.

15. The method of claim 11, further comprising lowering a pH of the low oxygen demand liquid to less than about 9.

16. The method of claim 11, wherein the free radical generator comprises at least one channel disposed to flow the low oxygen demand liquid therethrough, the channel comprising a metal selected from the group consisting of titanium and titanium alloy.

17. The method of claim 16, wherein a surface of the channel comprises a coating capable of catalytically promoting free radical production in the low oxygen demand liquid.

18. The method of claim 17, wherein the coating comprises titanium dioxide.

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Description

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BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to apparatus for generating free radical species and particularly to hydroxyl free radical generators and methods of use in water treatment facilities.

2. Description of Related Art

The use of aquatic systems for use by the general public, for example, swimming pools, spas, hot tubs, decorative fountains, cooling towers and the like, has led to a variety of water quality problems. For instance, improper chemical balances in the water can lead to various types of contamination including bacterial and viral contamination. To address such problems, pool operators have turned to the use of chemical sanitizers as a typical water sanitation method. Halogen donor compounds, such as chlorine or bromine can be effective sanitizers so long as they are maintained at well-defined and constantly controlled concentration levels in the water. It is important that the concentration of these chemical sanitizers is not allowed to become too high and possibly cause irritation to the users and damage to the water system. Insufficient sanitizers may result in a contaminated condition. Other systems have been developed. For example, Ruffin in U.S. Pat. No. 3,079,498 discloses a swimming pool water purifier that provides germicidal ultra-violet radiation to a stream from and to the swimming pool.

Other efforts aimed at sanitization or treating aquatic systems have been disclosed. For example, Czulak et al., in U.S. Pat. No. 3,336,099, disclose an apparatus for the sanitization of liquids with special application to water storages and swimming pools by passing such a liquid from the swimming pool around an ultraviolet radiation source to expose the liquid to said radiation. Koubek, in U.S. Pat. No. 4,012,321, discloses oxidation of refractory organics in aqueous waste streams by hydrogen peroxide and ultraviolet light by introducing the liquid to be treated in a photolysis chamber, to expose the liquid to the ultraviolet light. Pisani, in U.S. Pat. No. 4,906,387, discloses a method for removing oxidizable contaminants in cooling water used in conjunction with a cooling tower by including means for removing a portion of the recirculating water which passes through the cooling tower to create a slipstream of water to be treated and treating the slipstream water with chemicals to provide a hydroxyl free radical into the water to enhance oxidation, inducing cavitation in the slipstream water, then irradiating the slipstream water with ultraviolet radiation to thereby cause the oxidizable contaminants to be oxidized and therefore removed before the slipstream water is reintroduced back into the cooling tower. Cater et al., in U.S. Pat. No. 5,043,080, disclose treating contaminated effluents and ground waters wherein the liquid effluent or ground water containing the organic contaminants is contacted with hydrogen peroxide and transition metal ions; the hydrogen peroxide and transition metal ions are present in effective amounts based on the concentration of the organic contaminants in the liquid and the liquid effluent is then irradiated with ultraviolet light to decompose the organic contaminants. Weres et al., in U.S. Pat. No. 5,439,577, disclose an electrochemical device for generating hydroxyl free radicals in the treated water using a novel electrode which is capable of operation at sufficiently positive anodic potential to produce the hydroxyl radicals in the treated water.

SUMMARY OF THE INVENTION

According to one embodiment, the present invention provides a water system comprising a body of water and a free radical generator comprising an inlet connectable to a substantially pure water source, a channel fluidly connected to the inlet, the channel disposed to flow the substantially pure water therethrough, an ultraviolet radiation emission source disposed to irradiate the substantially pure water and generate free radicals therein, and an outlet fluidly connected to the body of water.

According to another embodiment, the present invention provides a method of minimizing undesirable species in a water system. The method comprises providing substantially pure water to a free radical generator, irradiating the substantially pure water with ultraviolet radiation to produce a solution comprising free radicals, and adding the solution to the aquatic system.

According to another embodiment of the present invention, a method for disinfecting an aquatic system is provided. The method includes providing a low oxygen demand liquid to a hydroxyl free radical generator, irradiating the low oxygen demand liquid with actinic radiation to generate hydroxyl free radicals in the liquid, and adding the hydroxyl free radicals to the aquatic system.

According to another embodiment of the present invention, a method for facilitating treating a water facility is provided. The method includes providing a reactor comprising a water inlet fluidly connectable to a substantially pure water source, a channel fluidly connected to the inlet, the channel disposed to flow the substantially pure water therethrough, an ultraviolet radiation emission source disposed to irradiate the substantially pure water and generate hydroxyl free radicals therein and an outlet downstream of the ultraviolet radiation emission source, the outlet fluidly connectable to the water facility.

In another embodiment, the present invention provides a method of operating a water system. The method comprises the steps of providing a reactant solution consisting essentially of substantially pure water, irradiating the reactant solution with ultraviolet light to produce an oxidant solution having free radical species and mixing the oxidant solution with water in the water system.

In another embodiment, the present invention provides a water system. The water system comprises a reactant solution source providing reactant solution consisting essentially of water substantially free of free radical