System and method for treating water

• US 5,433,866 A
• Filed: 03/18/1994
• Issued: 07/18/1995
• Est. Priority Date: 06/15/1992
• Status: Expired due to Fees

• Current Assignee: Phoenix Project Trust
• Original Assignee: Pollution Management Industries PMI
• Inventors: Hoppe, Jeffrey E., Watkins, Gerald O.
• Primary Examiner(s): McCarthy, Neil
• Application Number:
  US08/210,706
• Time in Patent Office: 487 Days
• Field of Search: 210/760, 210/748
• US Class Current: 210/748.11
• CPC Class Codes: C02F 1/325 Irradiation devices or lamp constructions
• CPC Class Codes: C02F 1/78 with ozone C02F1/4672 takes precedence
• CPC Class Codes: C02F 2201/3221 Lamps suspended above a water surface or pipe

Abstract

A method for treating wastewater and for purifying and disinfecting drinking water. The treatment includes the addition of pressurized ozonated air to the pumped raw water stream by use of a venturi injector and then achieving well-mixed ozonated water by an in-line static mixer. This promotes the ozone reaction with pollutants in the raw water. The stream is then injected into the ultraviolet (UV) reaction chamber by a static impinger in the form of a conical spray nozzle. This breaks up the stream into a fine mist of one-micron diameter droplets falling down through the chamber. Air released from the droplets is suitably vented to keep the chamber pressure near atmospheric. At a lower plane in the chamber, a UV light source in the form of a uniform grid of essentially coplanar UV lamps irradiates the falling droplets to kill bacteria and viruses and also to catalyze the still ongoing ozone reaction. In the bottom of the chamber, the now treated water forms a pool which is pumped out through filters to its final point of use.

A low residence time of two minutes results from optimum process criteria and chamber geometry. The former include a 20:1 mixture ratio of raw water to ozonated air in the inflow and a pressure of several atmospheres going into the spray nozzle. The latter include a conical chamber roof to facilitate proper droplet motion, the specified placement of the UV light source in a horizontal plane, and a curved chamber bottom to keep any particulates in suspension and enhance drainage of the treated water.

Claims

1. A method for treating, purifying, and disinfecting a water stream containing impurities by the use of ozone and ultraviolet light, comprising the steps of:

pressurizing the water stream;

producing a pressurized ozonated air stream;

mixing the water stream and the ozonated air stream to form a pressurized ozonated water stream in which the ozone starts to react with the impurities in the water;

introducing the pressurized ozonated water stream in the form of a conically shaped fine mist of droplets having a diameter of about one micron into a closed reaction chamber having a conically shaped roof with a residence time of said water stream as it flows through said chamber of approximately two minutes;

causing the fine mist of droplets to fall under gravity in said chamber with concomitant escape of reacted ozonated air from said droplets into said chamber;

venting said escaping ozonated air from said chamber by venting means effecting a desired pressure level in said chamber;

producing an ultraviolet light zone in a lower region of said chamber to react directly with impurities in said droplets and catalyze the ongoing action of ozone on said droplets;

collecting said droplets after passing through the ultraviolet light zone into a pool of treated water at the bottom of said chamber; and

discharging the treated water from the bottom of said chamber through filter means.

2. The method of claim 1, wherein the step of pressuring the water stream includes pressurizing to a pressure in the range from 30 to 160 psig.

3. The method of claim 1, wherein the step of producing a pressurized ozonated air stream includes producing said stream at a pressure in the range from 15 to 25 psig.

4. The method of claim 1, wherein the step of mixing the water stream and ozonated air stream includes initial mixing in a venturi injector designed for a mixture of one volume of ozonated air with twenty volumes of water, and passing the pressurized ozonated water stream through an in-line mixer.

5. The method of claim 1, wherein the step of venting ozonated air from the chamber by venting means effecting a desired pressure level in said chamber includes a pressure level in the range from zero to five psig.

6. The method of claim 1, wherein the step of producing an ultraviolet light zone in the lower region of the chamber includes a horizontal light zone providing uniform illumination.

7. The method of claim 1, wherein the step of collecting droplets into a pool of treated water at the bottom of said chamber includes a curved chamber bottom to keep any particulates suspended in the water and facilitate draining.