Method for disinfecting a dense fluid medium in a dense medium plasma reactor

• US 6,749,759 B2
• Filed: 07/12/2002
• Issued: 06/15/2004
• Est. Priority Date: 07/12/2002
• Status: Active Grant

• Current Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Original Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Inventors: Denes, Ferencz S., Manolache, Sorin O., Somers, Eileen B., Wong, Amy C. Lee
• Primary Examiner(s): LAWRENCE JR, FRANK M
• Application Number:
  US10/194,751
• Publication Number:
  US 20040007539A1
• Time in Patent Office: 704 Days
• Field of Search: 210/748, 210/764, 210/192, 210/243, 422/29, 422/186.21, 205/742, 205/755, 205/560
• US Class Current: 210/748.17
• CPC Class Codes: C02F 1/34 with mechanical oscillations
• CPC Class Codes: C02F 1/4606 for producing oligodynamic substances to disinfect the water
• CPC Class Codes: C02F 1/4608 using electrical discharges
• CPC Class Codes: C02F 2001/46133 characterised by the material
• CPC Class Codes: C02F 2301/08 Multistage treatments, e.g. repetition of the same process step under different conditions
• CPC Class Codes: C02F 2303/04 Disinfection
• CPC Class Codes: C02F 2305/023 Reactive oxygen species, singlet oxygen, OH radical
• CPC Class Codes: C02F 2305/10 Photocatalysts

Abstract

A method for disinfecting water and other dense fluid media containing microorganisms is carried out in a dense media plasma reactor. The plasma reaction in the reactor produces reactive species, such as electrons, ions, and free radicals that promote the inactivation of the microorganisms. In various embodiments, the plasma reaction also sputters off minute antimicrobial particles of the electrically conducting material from which the electrodes are made.

Claims

1. A method of disinfecting a dense fluid medium containing at least one microorganism, the method comprising:

(a) providing a reaction vessel for containing a dense fluid medium, the dense fluid medium containing at least one microorganism;

(b) charging the dense fluid medium into the reaction vessel;

(c) providing a first electrode comprising a first conductive material, the first electrode immersed within the dense fluid medium;

(d) providing a second electrode comprising a second conductive material, the second electrode immersed within the dense fluid medium and disposed opposite the first electrode;

(e) stirring the dense fluid medium between the first and second electrodes;

(f) applying an electric potential between the first electrode and the second electrode to create a discharge zone comprising a plurality of discharges wherein the electric potential is high enough to produce reactive species in the dense fluid medium; and

(g) exposing the microorganisms in the dense liquid medium to the reactive species in the dense fluid medium for a time sufficient to at least partially inactivate the microorganisms.

2. The method of claim 1 wherein the reactive species are selected from the group consisting of electrons, ions, free radicals, and mixtures thereof.

3. The method of claim 1 wherein the microorganism is a bacteria.

4. The method of claim 1 wherein the bacteria is a spore.

5. The method of claim 1 wherein the first electrode is a rotating electrode and the second electrode is a stationary electrode.

6. The method of claim 1 wherein the second electrode is hollow and includes at least one conduit for passage of the dense fluid medium.

7. The method of claim 5 wherein the first electrode rotates at a rate sufficient to cause cavitation in the dense fluid medium.

8. The method of claim 5 wherein the first electrode rotates at a speed of up to about 5000 RPM.

9. The method of claim 5 wherein the first electrode rotates at a speed of at least about 1000 RPM.

10. The method of claim 1 wherein at least one of the first conductive material or the second conductive material comprises an electrical conductor selected from the group consisting of metals, carbon or combinations thereof.

11. The method of claim 1 wherein at least one of the first conductive material or the second conductive material comprises an electrical conductor selected from the group consisting of aluminum, antimony, bismuth, carbon, copper, gold, iron, lead, molybdenum, nickel, platinum, silver, tin, tungsten, zinc, stainless steel, rare earths or combinations thereof.

12. The method of claim 1 wherein at least one of the first conductive material or the second conductive material comprises titanium.

13. The method of claim 1 wherein at least one of the first conductive material or the second conductive material comprises iron.

14. The method of claim 1 wherein at least one of the first conductive material or the second conductive material comprises stainless steel.

15. The method of claim 1 including the step of passing a gas through the discharge zone.

16. The method of claim 1 wherein the first electrode and the second electrode each comprise at least one planar surface, wherein the planar surface of the first electrode is substantially parallel to the planar surface of the second electrode.

17. The method of claim 16 wherein the substantially planar parallel surfaces are separated by a gap of about 1 mm.

18. The method of claim 16 wherein the first electrode comprises at least one pin made of the first conducting material, the pin projecting from the planar surface of the first electrode towards the planar surface of the second electrode.

19. The method of claim 16 wherein the first electrode comprises multiple pins made of the first conducting material, the pins projecting from the planar surface of the first electrode towards the planar surface of the second electrode.

20. The method of claim 19 wherein the pins are arrayed in a spiral pattern.

21. The method of claim 1 wherein the electric potential is between 100 and 800 volts.

22. The method of claim 1 wherein the electric potential is between 100 and 250 volts.

23. The method of claim 1 wherein the electric potential is about 200 volts.

24. The method of claim 1 wherein at least one of the first conductive material or the second conductive material comprise a material having antimicrobial properties and further wherein the electric potential between the first electrode and the second electrode is sufficient to dislocate antimicrobial nanoparticles from the electrode comprising the material having antimicrobial properties.

25. The method of claim 24 wherein the material having antimicrobial properties is silver.

26. The method of claim 1 further including mixing a colloidal suspension of antimicrobial nanoparticles with the dense fluid medium.

27. A method of disinfecting a dense fluid medium containing at least one microorganism, the method comprising:

(a) providing a first reaction container for containing a dense fluid medium, the dense fluid medium containing at least one microorganism;

(b) charging the dense fluid medium into the first reaction container;

(c) providing a first electrode comprising a first conductive material, the first electrode immersed within the dense fluid medium and housed in the first reaction container;

(d) providing a second electrode comprising a second conductive material, the second electrode immersed within the dense fluid medium and disposed opposite the first electrode in the first reaction container;

(e) applying an electric potential between the first electrode and the second electrode to create a discharge zone comprising a plurality of discharges wherein the electric potential is high enough to produce reactive species in the dense fluid medium;

(f) providing a second reaction container for containing a dense fluid medium, the second reaction container connected to and in fluid communication with the first reaction container through an inlet port;

(g) changing the dense fluid medium between the first reaction container and the second reaction container;

(h) providing a third electrode comprising a third conductive material, the third electrode immersed within the dense fluid medium and housed within the second reaction container;

(i) providing a fourth electrode comprising a fourth conductive material, the fourth electrode immersed within the dense fluid medium and disposed opposite the third electrode in the second reaction container;

wherein at least one of the third conductive material or the fourth conductive material comprises a material having antimicrobial properties and, further, wherein the electric potential between the third electrode and the fourth electrode is high enough to dislocate antimicrobial nanoparticles from the at least one conductive material having antimicrobial properties.