GB2350106A

GB2350106A - Destroying pathogens using ultrasound radiation

Info

Publication number: GB2350106A
Application number: GB9825349A
Authority: GB
Inventors: Darren Miles Bates
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-11-20
Filing date: 1998-11-20
Publication date: 2000-11-22
Also published as: GB9825349D0

Abstract

In apparatus and method for destroying pathogens in a liquid or a mass of a liquid containing material, the liquid or liquid mass is irradiated with continuous ultrasound radiation of a frequency between 15 and 100 kHz, preferably 20 Ò 1 kHz, by means of a transducer 4 in a sonication chamber 1. Preferably, the radiation power output is in the range 50-500 watts per cubic centimetre of material being treated, the amplitude of the radiation is advantageously greater than a 50 micron displacement and the method is preferably carried out at a temperature of about 15{ centigrade. The transducer 4 comprises probes from which the radiation is emitted either from the whole surface area of the or each probe or preferably just from the tip. The ultrasound radiation may be combined with other forms of energy such as ultraviolet or microwave radiation, or with chemical treatment, such as with ozone.

Description

2350106 4 f APPARATUS FOR AND METHOD OF DESTROYING PATHOGEN The present

invention relates to apparatus for and method of destroying pathogens in a liquid in which the liquid-or a liquid containing mass of material is irradiated with ultrasound energy.

According to one aspect of the present intention there is provided a method of destroying pathogens in a liquid or a mass of liquid containing material in which the liquid is irradiated with continuous ultrasound radiation of a frequency between 15 and 100 kHz.

According to another aspect of the present invention there is provided apparatus for destroying pathogens in a liquid comprising means for containing the liquid, and a transducer for irradiating liquid or a liquid containing mass of material in the means for containing with ultrasonic energy at a frequency within the range 15 to 100 kHz.

In a preferred embodiment of the invention, the frequency of the ultrasound radiation is 20:t 1 kHz. Advantageously, the power output of the radiation is grater than or equal to 0.1 Watts per cubic centimetre and preferably in the range 50-500 watts per cubic centimetre of material being treated. Preferably, the amplitude of the radiation is greater than or equal to a 10 micron displacement and advantageously greater than a 50 micron displacement. The method may be carried out at a temperature in the range 0-90o centigrade and preferably about 15o centigrade. The ultrasound radiation may be emitted from the whole surface area of the or each probe or, most advantageously just from the tip of the or each probe. The type of ultrasonic emission from the or each probe may be radial wave ultrasound or most advantageously, focussed energy. The internal diameter of the sonication chamber may be less than or equal to 20 inches and most advantageously is 2 inches. The or each probe may be made from titanium, stainless steel, aluminium, hastalloy, or any other suitable material, but is advantageously made of titanium. The sonication chamber may be circular, square, rectangular, triangular, polygonal or rhomboid, or any other suitable cross-section but is preferably of circular cross-section. The ultrasound radiation may be combined with other forms of electro-magnetic energy such as ultraviolet radiation, microwave radiation laser waves. Chemicals such as ozone may be used. Filters and/or reverse osmosis membranes and/or sonication of side tank following back flushing of filters into the tank may also be used. Any combination of these energy forms, chemicals.

filters, membranes and side tank sonication may also be used.

In order that the invention may be more clearly understood, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure la diagrammatically shows a cross-section through a sonication chamber, Figure 1 b diagrammatically shows a longitudinal section through the sonication chamber of figure la, Figure 2 diagrammatically shows a cross-section through a second form of sonication chamber, Figure 3 diagrammatically shows a cross-section through a third form of sonication chamber, Figure 4 diagrammatically shows a cross-section through a fourth form of sonication chamber, Figure 5 diagrammatically shows a cross-section through a fifth form of sonication chamber, Figure 6 diagrammatically shows a perspective view of a sixth form of sonication chamber, Figure 7 diagrammatically shows a sectional view through an alternative type of sonication chamber, Figure 8 diagrammatically shows a sectional view through a modification of the chamber of figure 7, and Figure 9 diagrammatically shows a further form of sonication chamber.

Referring to figures la and lb, a simple sonication chamber comprises a substantially cylindrical chamber 1 having a fluid inlet 2 and a fluid outlet 3. A transducer 4 extends into the chamber. The transducer is a 1 or 2 KW transducer and operates at a frequency of 20kHz.

-4 The chamber of Figure 2 is similar to that of Figure 1 except that two diametrically opposed transducers 4 are provided each operating at the power levels and frequency of the transducer of the embodiment of Figure 1. The chamber of Figure 3 has three equiangularly spaced'transducers 4 that of Figure 4 four such transducers and that of Figure 5 eight such transducers. In these further examples, each transducer operates at the power levels and frequency of the transducer of the embodiment of Figure In the embodiment of Figure 6 twelve transducers 4 are arranged in three groups of four spaced along the axial length of the cylindrical chamber 1. The transducers of each group of four are equiangularly spaced in a manner similar to the arrangement of Figure 4. For simplicity the inlet and outlet to the chamber 1 are not shown.

The above embodiments may be employed according to the following parameters. The or each transducer is activated to supply continuous ultrasound energy to liquid flow through the chamber. The surface of the or each transducer is in contact with the medium to be sonicated. The or each transducer is not fixed or welded to or in contact with the side of the corresponding chamber. As many transducers of as high a power as possible are employed. The following tables give possible ranges and most advantageous values for a variety of parameters.

Parameter Possible/Pref erred Most Advantageous Range Value Frequency 15-100 kHz 20 kHz Power Intensity O.l W/CM3 100 W/C M3 or higher if technology permits Power 1 or more transducers 2 kW transducers or each of 100 W or higher if technology above permits Arrangement of See Figure 1 See Figure 1 transducers Amplitude 10 micron 50 micron displacement displacement or greater if technology permits Temperature 0-900C 150C Site of ultrasonic Whole surface area of The tip of the probe emission on probe the probe or just at the surface tip of the probe Type of ultrasonic Radial wave ultrasound Focussed energY emission from or focussed.energy probe Internal diameter 2!20 inches 2 inches of sonication chamber Material from Titanium, Stainless Titanium which probe is steel, aluminium, made hastalloy Geometry of flow Circular, square, Circular cell rectangular, triangular, polygonal, rhomboid ntional Parameters Parameter Possible/Preferred Most Advantageous Range Value Viscosity 1-10 cps n/a (cps = centrepoise) Flow Rate Static up to 10,000 n/a gallons per minute The following give brief details of two tests carried out to purify water.

Test 1 A 5 litre sample of water spiked with 109 concentration of Salmonella, Exoli, Cryptosporidium, Ascaris, Poliovirus was sonicated for seconds using a 1000 W, 20 kHz ultrasonic reactor.

Results The water was analysed after sonication, and the result was found to be a log 7 reduction (100% kill) of Salmonella, Exoli, Cryptosporidium, Ascaris and Poliovirus.

Test 2 A sample of water spiked with 109 concentration of Salmonella, Exoli, Cryptosporidium, Poliovirus was passed once through an ultrasonic flow-through reactor, 2 KW, 20kHz, at a rate of 30 litres per minute.

Results The water was analysed after sonication, and the result was found to be between a log 4 and a log 7 reduction of Salmonella, E.coli, Cryptosporidium, Ascaris and Poliovirus.

Figures 7, 8 and 9 show alternative arrangements employing alternative types of transducer. In the embodiment of Figure 7, a focussed energy transducer 9 extends into an open bath 10 having an inlet 11 and an outlet 12. With such an arrangement, a lower flow rate of fluid, in which pathogens are to be destroyed, is possible. The fluid flows into the bath 10 via the inlet 11 and out of the bath via the outlet 10. In the embodiment of Figure 8, a radial wave transducer 15, which emits energy from its entire surface area, is used. As can be seen, the transducer again extends into an open bath 16 and pathogen containing fluid flows into the bath via the inlet 17 and out of the bath via an outlet 17. The transducer is energised as before to destroy the pathogens in the fluid. The transducer may be used with static fluid as well as flowing water. Rate of flow may be altered by adjusting dimension Y. This may be 0.5cm, for example. Figure 9 shows an arrangement in which a transducer 20 is disposed in a beaker 21 containing static minced beef to be sonicated.

The following table gives parameter values for a series of three tests (i), (5) and (iii) using the arrangements of Figures 7, 8 and 9 for the ultrasonic treatment of minced beef.

Parameter Test (i) Test (ii) Test (iii) Frequency 20 kHz 20 kHz 20 kHz Power intensity 0.3 W/CM3 2,800 W/cm' 4.0 W/CM 3 Power 700 W 1400 W 200 W Pulsed/continuous Continuous Continuous Continuous ultrasonic energy Amplitude 20 microns 25 microns 20 microns Temperature 20oC 20oC 20oC Flow cell 50 cm 0.5 CM3 volume 70 cm diameter dimensions diameter Geometry of flow Circular Circular Circular cell/container Flow rate Static 5 Static gallons/minute Arrangement of See Figure 3 See Figure 3 See Figure 4 transducers The ultrasonic radiation may be with any one or more of the following 0 ultraviolet 0 ozone 0 microwave energy 0 laser energy 0 chemicals 0 any form of electro-magnetic energy 0 filters and/or reverse osmosis membranes and/or sonication of t 1 -9side tank following back-flushing of filters into the tank.

The method may be carried out at ambient temperature and pressure or at any other suitable temperature and pressure.

It will be appreciated that the above embodiment has been described by way of example only and that many variations are possible without departing from the scope of the invention.

Claims

-10CLAIMS

1 A method of destroying pathogens in a liquid or a mass of liquid containing material in which the liquid is irradiated with continuous ultrasound radiation of a frequency between 15 and 100 kHz.

2. A method as claimed in claim 1, in which the power output of the radiation is greater than or equal to 0.1 watts per cubic centimetre of material being treated.

3. A method as claimed in claim 1 or 2, in which the power output of the radiation is in the range 50-500 watts per cubic centimetre of material being treated.

4. A method as claimed in claim 1, 2 or 3, in which the amplitude of the radiation is equal to or greater than a 10 micron displacement.

5. A method as claimed in claim 1, 2, 3, or 4, in which the amplitude of the radiation is greater than a 50 micron displacement.

6. A method as claimed in any preceding claim, in which the temperature lies in the range 0-90o centrigrade.

7. A method as claimed in claim 6, in which the temperature is about 15oC.

8. A method as claimed in any preceding claim, in which the radiation is radial wave.

9. A method as claimed in any of claims 1 to 7, in which the radiation is focussed energy.

10. A method as claimed in any preceding claim, in which the continuous ultrasound radiation is combined with ultraviolet radiation.

11. A method as claimed in any preceding claim, in which the continuous ultrasound radiation is combined with microwave radiation laser waves.

12. A method as claimed in any preceding claim, in which a chemical is added.

13. A method as claimed in claim 12, in which the chemical is ozone.

14. A method of destroying pathogens substantially as hereinbefore described with reference to Figures 1 a and 1 b, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6, Figures 7 and 8 or Figure 9 of the accompanying drawings.

15. Apparatus for destroying pathogens in a liquid comprising means for containing the liquid, and a transducer for irradiating liquid or a liquid containing mass of material in the means for containing with ultrasonic energy at a frequency within the range 15 to 100 kHz.

16. Apparatus as claimed in claim 15, in which the transducer comprises one or more probes.

17. Apparatus as claimed in claim 16, in which the transducer is operative to irradiate from the whole surface area of the or one of the probes.

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18. Apparatus as claimed in claim 16, in which the transducer is operative to irradiate from the tip of the or one of the probes.

19. Apparatus as claimed in claim 16, 17 or 18, in which the or each transducer probe is operative to radiate radial wave ultrasound.

20. Apparatus as claimed in claim 16, 17 or 18, in which the or each transducer probe is operative to radiate focussed energy.

21. Apparatus as claimed in any of claims 16 to 20, in which the or each probe is made from titanium, stainless steel, aluminium, hastalloy or other suitable material.

22. Apparatus as claimed in any of claims 15 to 21, in which the internal diameter of the sonication chamber is less than or equal to 20 inches.

23. Apparatus as claimed in any of claims 15 to 22, in which the internal diameter of the sonication chamber is 2 inches.

24. Apparatus as claimed in any of claims 15 to 23, in which the sonication chamber is circular, square, triangular, polygonal or rhombic cross-section.

25. Apparatus as claimed in any of claims 15 to 24, in which means are provided for producing ultraviolet radiation.

26. Apparatus as claimed in any of claims 15 to 24, in which means are provided for producing microwave radiation.

27. Apparatus as claimed in any of claims 15 to 26, in which filters are provided.

28. Apparatus as claimed in any of claims 15 to 26, in which reverse osmosis membranes are provided.

29. Apparatus for destroying pathogens substantially as hereinbefore described with reference to Figures 1 a and 1 b, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6, Figures 7 and 8 or Figure 9 of the accompanying drawings.