System and method for dissolving gases in liquids

• US 20050279713A1
• Filed: 05/25/2005
• Published: 12/22/2005
• Est. Priority Date: 05/25/2004
• Status: Active Grant

• Current Assignee: The Board of Trustees of the University of Arkansas (University of Arkansas System)
• Original Assignee: Gregory Scott Osborn, Marty D. Matlock, Shandi S. Teltschik
• Inventors: Osborn, Gregory Scott, Matlock, Marty D., Teltschik, Shandi S.
• Granted Patent: US 7,255,332 B2
• Time in Patent Office: Days
• US Class Current: 210/760
• CPC Class Codes: B01F 23/23 by introducing gases into liquid media, e.g. for producing aerated liquids
• CPC Class Codes: B01F 23/234 Surface aerating
• CPC Class Codes: B01F 23/237611 Air
• CPC Class Codes: B01F 23/454 by injecting a mixture of liquid and gas
• CPC Class Codes: B01F 25/31331 Perforated, multi-opening, with a plurality of holes
• CPC Class Codes: B01F 25/32 wherein the additional components are added in a by-pass of the main flow
• CPC Class Codes: C02F 1/70 by reduction C02F1/4676 takes precedence
• CPC Class Codes: C02F 1/72 by oxidation C02F1/4672 takes precedence
• CPC Class Codes: C02F 1/727 using pure oxygen or oxygen rich gas
• CPC Class Codes: C02F 1/74 with air aeration of stretches of water C02F7/00
• CPC Class Codes: C02F 1/763 Devices for the addition of such compounds in gaseous form
• CPC Class Codes: C02F 1/78 with ozone C02F1/4672 takes precedence
• CPC Class Codes: C02F 2101/305 Endocrine disruptive agents
• CPC Class Codes: C02F 2101/306 Pesticides
• CPC Class Codes: C02F 2103/007 Contaminated open waterways, rivers, lakes or ponds
• CPC Class Codes: C02F 2103/343 from the pharmaceutical industry, e.g. containing antibiotics
• CPC Class Codes: C02F 2209/02 Temperature
• CPC Class Codes: C02F 2209/22 O2
• CPC Class Codes: C02F 2303/04 Disinfection
• CPC Class Codes: C02F 7/00 Aeration of stretches of water
• CPC Class Codes: Y02W 10/10 : Biological treatment of water, waste water, or sewage
• CPC Class Codes: Y02W 10/37 : using solar energy

Abstract

Apparatus and methods for dissolving a gas into a liquid comprises a saturation tank, a high pressure liquid pump in fluid communication with the tank, and a pressurized gas source in communication with a regulated gas head space of the saturation tank. The saturation tank comprises a pressure vessel for containing the liquid and has a regulated gas head space above the liquid, contains at least one liquid spray nozzle that permits passage of liquid into the pressure vessel, and an outlet for the liquid containing dissolved gas. Upon passing the gas-containing liquid into a second fluid, the gas is released in the form of microbubbles. The microbubbles aid in flocculation of suspended particles and promote dissolution of the gas in the second fluid. Preferred gases for use with the apparatus are oxygen, air, and ozone. Anticipated uses include treatment of rivers, streams, and ponds in natural or industrial settings, as well as smaller scale applications.

Claims

1. An apparatus for dissolving a gas in a liquid comprising:

(a) a saturation tank comprising (i) a pressure vessel for containing the liquid and providing a regulated gas head space above the liquid, (ii) at least one liquid spray nozzle that permits passage of liquid into the pressure vessel, and (iii) an outlet for the liquid;

(b) liquid pumping means in fluid communication with the at least one liquid spray nozzle;

(c) a source of the gas in communication with the regulated gas head space of the saturation tank; and

(d) a chamber external the saturation tank and connected thereto via the liquid outlet, which chamber is provided with a plurality of orifices through which liquid containing dissolved gas from the saturation tank can be released into a region external the chamber.

2. The apparatus of claim 1, wherein said region external the chamber has a lower pressure than internal the chamber, so that the saturation concentration for the dissolved gas in liquid exiting the chamber is exceeded and microbubbles of gas are formed at or near the chamber orifices.

3. The apparatus of claim 2, wherein the microbubbles have an average diameter less than about 150 microns.

4. The apparatus of claim 1, wherein the gas is selected from the group consisting of air, oxygen, ozone, hydrogen, nitrogen, nitrous oxide, and carbon dioxide.

5. The apparatus of claim 1, wherein the liquid primarily comprises water.

6. The apparatus of claim 1, wherein the pressurized pumping means is provided by (i) a high pressure liquid pump, (ii) a line source in a residential or industrial setting, or (iii) a plurality of fixed volume vessels capable of forcing liquid into the saturation tank upon pressurization of the fixed vessel with a high pressure gas that enters the vessel and displaces the liquid through an outlet in the vessel.

7. The apparatus of claim 1, wherein the ratio of liquid volume to head space gas volume in the saturation tank is maintained with an open-loop or closed-loop control system.

8. The apparatus of claim 1, wherein the number, size, and placement of orifices in said chamber are predefined so as to permit the rate of liquid flow rate out of the chamber to balance the rate of liquid flow into the saturation tank, thereby maintaining a constant desired pressure internal the saturation tank under constant flow conditions.

9. The apparatus of claim 1, wherein the orifices have a diameter in the range of about 1 mm to about 15 mm.

10. The apparatus of claim 1, wherein said chamber is provided internal a liquid entrainment means, so that the liquid containing dissolved gas exiting the chamber mixes with lower pressure ambient liquid.

11. The apparatus of claim 1, wherein the gas saturation threshold for the liquid is thermally controlled.

12. The apparatus of claim 1, wherein said at least one spray nozzle is adjustable so as to optimize the liquid droplet size and control the rate of gas saturation in the liquid.

13. The apparatus of claim 1, wherein the source of gas comprises means for separating oxygen from ambient air.

14. The apparatus of claim 1, wherein the source of gas comprises an ozone generator provided internal the saturation tank.

15. The apparatus of claim 1, further comprising a control system for controlling operation of the apparatus.

16. The apparatus of claim 1, further comprising a feedback loop that permits recovery and recycling of the gas to the saturation tank.

17. A method of dissolving a gas in a liquid comprising:

(a) pressurizing an enclosed vessel with the gas;

(b) spraying a first portion of the liquid into the vessel containing the gas under conditions effective to dissolve the gas in the liquid;

(c) passing the first portion of liquid containing dissolved gas from the vessel into a chamber that is provided with a plurality of orifices and which is immersed in a second portion of the liquid; and

(d) discharging the first liquid portion containing dissolved gas into the second liquid portion under conditions effective to form microbubbles of the gas in the second liquid portion at or near the chamber orifices.

18. The method of claim 17, wherein the gas is selected from the group consisting of air, oxygen, ozone, hydrogen, nitrogen, nitrous oxide, and carbon dioxide.

19. The method of claim 17, wherein the liquid primarily comprises water.

20. The method of claim 17, wherein the first portion of liquid is dissolved with gas to 95% of saturation at saturation tank pressure.

21. The method of claim 17, wherein the gas is separated on-site from ambient air prior to being pressurized into the vessel.

22. The method of claim 17, wherein the gas is ozone and the liquid is water to be purified for home, medical, or municipal use.

23. The method of claim 17, wherein the gas is provided by on-site generation.

24. The method of claim 17, wherein the liquid is provided by a water tap located in a residence or industrial site and liquid is transferred into the saturation chamber under tap pressure.

25. The method of claim 17, wherein the microbubbles have an average diameter less than about 150 microns.

26. The method of claim 17, which is performed in continuous mode.

27. The method of claim 17, wherein the gas enters the vessel at near ambient pressure and is pressurized via a closed system injection of liquid until a desired higher pressure is attained prior to discharge of the gas-containing liquid from the vessel.

28. The method of claim 17, wherein the liquid is sprayed into the vessel under pressure provided by a high pressure liquid pump.

29. The method of claim 17, wherein fluid flow into the vessel from a high pressure pump is controlled via feedback from sensors indicating water capacity within the saturation tank.

30. The method of claim 17, which is employed to:

(i) enhance microbe growth and respiration rate in waste water treatment, fermentation processes, food synthesis and manufacturing, or solid waste treatment;

(ii) promote physical flotation of matter suspended in the liquid;

(iii) quench anaerobic biological activity in the liquid;

(iv) produce nanobubbles (10-100 nm diameter);

(v) foam a polymer;

(vi) create a biorefuge for attracting or sustaining fish populations;

(vii) sterilize a body of water;

(viii) facilitate surface freezing while aerating/oxygenating during cold weather;

(ix) to control odor, antibiotic residuals, and/or bacterial loads in sewage transport conduits;

(x) improve the quality of water entering, transducing, or exiting a dam;

(xi) improving aerobic digestion efficiency and/or odor control in a wastewater treatment pond (lagoon);

(xii) respond to a pollutant spill into an environmental water body;

(xiii) isolate and/or treat a plume of pollution;

(xiv) disinfect and reduce organic carbon in drinking water;

(xv) control aerobic and anaerobic conditions in biological processes associated with pharmaceuticals and biotechnology;

(xvi) deliver hydrogen or other gases to create and control aerobic and anaerobic conditions in biological processes associated with in situ waste treatment in groundwater;

(xvii) deliver hydrogen or other gases to create and control aerobic and anaerobic conditions in biological processes associated with in situ waste treatment in surface waters;

(xviii) deliver a high concentration of dissolved oxygen to enhance biological oxidation of organic carbon and nitrogen removal within wastewater treatment facilities;

(xix) oxidize sediment in situ for enhanced bioremediation of contaminants sorbed to and associated with river, lake, and estuarine sediments;

(xx) enhance oxygen treatment of refractory pollutants such as antibiotic residuals, endocrine disruptors, pesticides, and similar chemicals;

(xxi) enhance ozone treatment of refractory pollutants such as antibiotic residuals, endocrine disruptors, pesticides, and similar chemicals;

(xxii) inject supersaturated stream of oxygen, ozone, hydrogen or other gases for direct treatment or enhancing treatment of groundwater to remove pollutants;

(xxiii) increase the rate of BOD removal because of improved treatment rate from smaller bubble size; and

(xxiv) increase the thickness of the aerobic layer in sediment for increase storage capacity of phosphorus or other water pollutants.