SYSTEM AND METHOD FOR STERILIZATION OF A LIQUID
Apparatus and method for sterilization of liquid includes a liquid container containing a liquid and having a piezoceramic ring that is connected to a power supply system. Power supply system supplies electric signals to the piezoceramic ring that are transformed into mechanical waves and cause vibrations in the liquid.
The present application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 60/324,281, filed Sep. 25, 2001, and claims priority under 35 U.S.C. § 120 of U.S. patent application Ser. No. 10/254,014, filed Sept. 25, 2002.
FIELD OF THE INVENTIONThe present invention relates to methods and apparatuses for sterilization of liquid, and more particularly, to such a method and apparatus that utilizes hydrodynamic focused and scanning cavitation.
BACKGROUND OF THE INVENTIONVarious methods have been employed for sterilization and purification of liquid. For example, UV radiation, disinfection by biocides and pasteurization have been used for water sterilization. Ultraviolet (UV) treatment has been used to disinfect clear water as described in U.S. Pat. Nos. 3,634,025; 3,700,406; 3,837,800; 3,889,123; 3,894,236; 4,471,225 and 4,602,162. Each of these U.S. patents describes a method for sterilization of water-based fluids. The principal idea behind these techniques is typically that UV radiation penetrates the clear liquid to kill offending microorganisms. UV has been also used in combination with magnetic treatment (e.g. U.S. Pat. No. 5,997,812) by passing the fluid through a magnetic field followed by exposure of the fluid to a disinfecting amount of ultraviolet radiation. The conventional technology of UV treatment is limited because systems made of quartz have a tendency to foul easily and maintenance costs are high.
Another approach to disinfect water is by adding appreciable levels of various biocide fluids to kill and inhibit the growth of microorganisms (e.g. U.S. Pat. No. 3,230,137). However, people exposed to biocides may experience allergic reactions or other problems. In short, although bacterial counts can be reduced over the short term, biocides are often more problematic than the microorganisms themselves.
Another method for the disinfection of fluids is pasteurization. In this process, fluids are heated to a pasteurizing temperature for a required period of time and subsequently cooled to an operating temperature. This process is energy intensive and the costs resulting from the heating and cooling steps are high.
Various other methods for sterilization, such as sterilization by ozone or H2O2, exist. However, these are either expensive, hazardous or not sufficiently effective.
SUMMARY OF THE INVENTIONEmbodiments of the present invention provide apparatus and methods for liquid sterilization based on focused acoustic vibration waves created in the liquid.
Embodiments of the invention relate to an apparatus and system for sterilization of liquid including at least one container suitable for containing a liquid and including an ultrasonic vibratable element.
According to further embodiments of the present invention the system may further include a power supply system operatively connected to the vibratable element. The power supply system may be adapted to supply electric waves having a preselected frequency or frequency range to the vibratable element.
According to some embodiments of the present invention the ultrasonic vibratable element may include a piezoceramic material. The piezoceramic material may be at least partially coated with a substantially conductive material. The conductive material may be operatively connected to the power supply system.
According to some embodiments of the present invention, the electric waves produced by the power supply system may have a frequency that substantially matches the resonance frequency of a system formed by the liquid, the cavity within which the liquid resides and the ultrasonic vibratable element. The electric wave may cause the ultrasonic vibratable element to oscillate. The oscillation of the vibratable element may be dependent upon the frequency or the frequency range of the electric waves, which may either be continuous or of a pulsing nature. In one embodiment, the electric waves may have a frequency that substantially matches the resonance frequency of the system comprising the liquid, the cavity and the piezoceramic material that may be included in the ultrasonic vibratable element.
According to some embodiments of the present invention the focused and scanning ultrasonic vibratable element may be adapted to cause liquid to vibrate at a preselected frequency or frequency range.
According to further embodiments the focused and scanning vibratable element may include a piezoceramic ring at least partially coated on the outer surface with a conducting material, and having various shapes, for example, cylindrical, convex, concave or tapered.
Some embodiments of the present invention also relate to a method for sterilization of liquid, the method including placing liquid in a container including at least one ultrasonic vibratable element, applying to the vibratable element electric waves at the frequency resonance of the vibratable element and of the liquid and producing acoustic vibration waves in the liquid.
The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the appended drawings in which:
It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.
DETAILED DESCRIPTION OF THE PRESENT INVENTIONIn the following description, various aspects of the invention will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the invention. However, it will also be apparent to one skilled in the art that the invention may be practiced without the specific details presented herein. Furthermore, well known features may be omitted or simplified in order not to obscure the invention.
Embodiments of the invention are directed towards methods and apparatuses for liquid sterilization. Embodiments of the invention provide methods and systems for the sterilization of non-flowing and flowing liquid.
Embodiments of the present invention may be directed towards an ultrasonic vibratable element. Such a vibratable element may include a piezoceramic material. The piezoceramic material may be selected from a group of piezoceramic materials including, but not limited to PZT-4, PZT-8, APC840, APC841, APC850, APC855, APC880 and APC856. However it should be noted that the vibratable element of embodiments of the present invention is not limited to include a piezoceramic material and other suitable material may also be used.
Reference is now made to
The vibratable element 2 may be attached to the inner portion of tube 30 as in
Power supply system 6 may be adapted to supply electric input to the vibratable element 2. The frequency of the electric input may be selectively controlled.
Electric input from the power supply 6 may be delivered to the conductive material of the vibratable element 2, which may then cause substantially ultrasound waves in the vibratable element 2. For example, the electric input delivered to the vibratable element 2 may cause thickness waves, longitudinal waves, waves that cause torsion in vibratable element 2 or any other acoustic waves.
In one embodiment of the invention, the sterilization may be achieved by supplying electric waves from the power supply system 6 to the vibratable element 2 in a direction that is substantially through the thickness of vibratable element 2. In this embodiment the selected frequency or frequency range of the electric waves supplied to the vibratable element 2 by the power supply system 6 may be in the MHz range. The selected frequency may be dependent upon various system 1 parameters, including, but not limited to the thickness of the vibratable element (e.g. the ceramic thickness of the piezoceramic material). For example, the frequency applied to a piezoceramic ring 2 with a thickness of 0.05 mm may be approximately 20 MHz and the frequency applied to a piezoceramic ring 2 with a thickness of 50 mm may be approximately 0.1 MHz. Other frequencies and thicknesses may be selected.
In one embodiment of the invention the sterilization may be achieved by applying a combination of two or more frequencies or frequency patterns of electric waves. For example, electric waves having a frequency in the KHz range may be supplied in the longitudinal direction, i.e., parallel to the length of the vibratable element 2. Electric waves having a frequency typically in the MHz range may be supplied trough the thickness of the vibratable element 2 as was described above for the thickness sterilization system. The frequency of the KHz electric waves may depend upon the thickness and length of the piezoceramic ring, and is typically between 20-500 KHz. Other frequencies and thicknesses may be selected.
In one embodiment of the invention, the sterilization may be achieved by applying a combination of three or more frequencies of frequency patterns of electric waves. The first two wave patterns may be supplied in the substantially longitudinal sterilization system, described above, e.g. the thickness waves and the longitude waves. The third wave pattern may be in the KHz range, typically between 15 to 300 KHz and may applied substantially through the thickness of the vibratable element 2 in addition to the two wave patterns supplied to the longitudinal sterilization system.
In response to the electric input generated by power supply system 6, the vibratable element 2 may oscillate, and may focus the center of the vibrating elements ultrasonic waves as depicted by arrow 36. For example, in response to the electric input the piezoceramic material that may be included in the vibratable element 2 may ultrasonically vibrate. These focused ultrasonic waves may initiate pressures in excess of several atmospheres, or bars, within the liquid, which pressures may cause the sterilization of the liquid 4. Without limiting the invention in any way, the sterilization of the liquid may be explained by the following: the progression of the ultrasound waves may create negative pressure in the liquid. The negative pressure may cause cavitation bubbles 18 (
Reference is now made to
In
In
By matching the supplied frequency to the system resonance frequency the pressure developed in the water at the middle of the container may considerably higher than when the frequency matches the piezoceramic material resonance alone. Thus, the highest efficiency of sterilization may be achieved when the electric input is compatible to the system frequency resonance.
Reference is now made to
The layer of matching material 3 may be adapted to gradually reduce the velocity of the vibrational waves between the velocity of the wave in the piezoceramic material (which may be approximately 3500-4500 m/sec but may be any other frequency) and the velocity of the wave in the liquid (which is for water 1560 m/sec), thus potentially minimizing the loss of energy due to drastic velocity changes.
By adding a layer of matching material between the piezoceramic ring and the water, and applying a signal of 1.1 MHz at a potential of 1 Volt, a pressure of approximately 12 atmospheres may be developed in the middle portion of the container. This pressure may be considerably higher than the pressure of 2.5 atmospheres developed when using a ring of piezoceramic material alone as illustrated in
Reference is now made to
Power supply system 6 may include the following: a pulse power supply 8, a MHz power supply 14, an amplifier 16, a controller 12, and a sensing device 10. Pulse power supply 8 may be adapted to provide electric waves to the piezoceramic vibratable element 2, possibly after amplification by amplifier 16. Sensing device 10 may be adapted to sense various system parameters, for example the sensing device 10 may be adapted to sense the resulting oscillation frequencies in the liquid. Controller 12 may be configured to receive input from sensing device 10 (e.g. oscillation frequencies in the liquid) and may issue control signal to the power supply 14 to supply electric waves having a desired frequency for obtaining frequency resonance in the vibratable element 2 and the liquid 4, thus possibly achieving high pressure in liquid 4 at the middle axis of container 29. The power supply system 6 may or may not supply a signal at a resonance frequency of the vibratable element 2 and the liquid 4. In alternate embodiments the sensing device 10 need not be used or may be omitted altogether.
Reference is now made to
Liquid may enter the upper portion of tube 30, as depicted by arrow 20, and may flow through it. The power supply system 6 may supply electric waves to the convex piezoceramic ring 2 in tube 30. The supplied electric waves may cause vibrational oscillations depicted by arrows 36, which may progress through the piezoceramic ring 2 and through the liquid 4. These vibrations may progress not only in the horizontal axis, as in the cylindrical piezoceramic ring, but also in other directions. As a result of these vibrations, an oval shaped high pressure area and cavitation bubbles 18 may be built up in the middle region of the tube. The high pressure and the cavitation may lead to the sterilization of the liquid in the oval region. Thus sterile liquid depicted by arrow 24 may exit the tube. The liquid 4 existing outside the cavitation region, as depicted by arrow 22, may not necessarily be sterile.
The system is similar to that described in
The system is similar to that described in
Reference is now made to
Reference is now made to
Sterilization system 1 may include container 29 with liquid 4 therein. Container 29 may have an inner or outer vibratable element 2 that may be coated with a conducting material and may be connected to a power supply system 6.
The power supply system 6 may include of the following: a pulse power supply 8, MHz and KHz power suppliers 14 and 15 respectively, a mixer 17, a controller 12 and an amplifier 16. Power supply system 6 may include other parts suitable for supplying electric waves to vibratable element 2.
A pulse power supply 8 may be adapted to supply electric waves having an initial frequency, the MHz power supply 14 may be adapted to supply electric waves at a frequency that may be required for generating thickness waves described in
The vibratable element 2 may oscillate in response to the combined electrical input. The MHz power supply 14 may cause thickness waves (not shown) and the KHz power supply 15 may cause longitudinal or bending waves 38. These waves when operating together may provide various shapes of cavitation regions, as will be described hereinbelow. Pulse power supply 8 and controller 12 may operate, similarly as was described for
Reference is now made to
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In
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The torsion forces may be achieved in the cylindrical piezoceramic ring as illustrated in
Tube 30 may include piezoceramic material having cavities thus creating small tubes wherein liquid can flow. These cavities may have any shape described above or any other suitable shape. The cavities may have a diameter range of preferably 0.1-1 micron; other dimensions may also be used. The power supply system may be connected to the tube which may be coated with a conducting layer.
Reference is made now to
The chamber may be connected to a power supply and signal generator. The power supply and signal generator may be operatively connected to the vibratable elements. The power supply and signal generator may be constructed in accordance with any of the configurations described above.
A liquid may enter the chamber 3300 through an opening 3312 from an outer source (not shown) to the portion labeled volume A, on either side of the outer section 3302, where the vibratable elements 3306 may be operated as described hereinabove, thereby causing acoustic vibrational oscillations in the liquid. Vibrations from the element 3306 in the outer direction may be reflected from the chamber's wall and may create standing acoustical pressure waves. This may initiate at least a partial liquid sterilization. The oscillation frequency of the vibratable elements 3306 element may be selected, such that the oscillation of the vibratable elements 3306 may cause standing waves in the liquid.
The liquid may proceed into the inner section 3304, labeled volume B, initiation focused acoustic pressure waves as described hereinabove with reference to
An experimental system was built from a 12 mm diameter cylindrical ring of a piezoceramic material PZT-4 with a thickness of 2 mm and a length of 20 mm. Water was flowing through the ring at a capacity of 1 cm/sec. The water contained an initial microbial concentration of bacteria per volume. The ring was connected to a power supply system as described in
The first microbial test was conducted by AminoLab Laboratory an officially recognized laboratory by Ministry of Agriculture, in Israel, according to the “Standard Methods for the Examination of Water and Wastewater” using the pour plate technique.
A second microbial test that includes a bacteria count and a mold count was conducted by MicroLab Laboratories, Rehovot, an officially recognized laboratory by Ministry of Agriculture, in Israel. The bacteria used were ERWINIA and CLAVIBACTER and the mold were ASPERILLUS and FUSARIUM. The Laboratory method was conducted according to the “Standard Methods for the Examination of Water and Wastewater” using the pour plate technique.
Six samples 1-6 were detected. Sample 6 is the control sample contains untreated examined water with initial bacterial count of 4×108 CFU/ml and mold count of 4.2×105 CFU/ml. Samples 3 and 4 are water exiting the experimental system described above after the operation of thickness sterilization system. The bacteria count of these samples was 1.2×107, 1.2×108 CFU/ml respectively and the mold count was <10 and 3×104 CFU/ml respectively. Samples 2 and 1 are water exiting the experimental system described above after the operation of longitudinal sterilization system, where the longitude mode is at the first and second mode as described in
For the samples exiting the thickness sterilization system no significant reduction of the bacteria count was achieved. For sample 2 and 1 exiting the longitudinal sterilization system where longitude vibrations were applied at the first and second mode of vibration a reduction of approximately 2 and 5 orders of magnitude was achieved in the bacteria count, respectively. For both samples the mold count was reduced to <10 CFU/ml. For sample 5 exiting the torsion sterilization system a reduction of 8 orders of magnitude was achieved in the bacteria count and the mold count was reduced to <10 CFU/ml.
The most efficient sterilization system as accepted at both laboratories is the system described in
While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
Claims
1. An apparatus to substantially sterilize a liquid comprising:
- a ring of vibratable material, said ring being of an arbitrary shape and length, and having an internal passage through which the liquid may flow, said ring further comprising a layer of matching material disposed between the ring and the liquid; and
- a power supply system connected to said ring and adapted to supply electric waves to said ring at a frequency estimated to be a resonance frequency of a system formed by said ring and the liquid.
2. The apparatus of claim 1, wherein said vibratable material is comprised of a piezoceramic material.
3. The apparatus of claim 2, wherein said piezoceramic material is coated on at least one surface by a conducting material.
4. The apparatus of claim 3, wherein said electric waves cause said ring to vibrate along its thickness.
5. The apparatus of claim 4, wherein said electric waves cause the ring to vibrate such that standing thickness waves are produced within the liquid.
6. The apparatus of claim 3, wherein said electric waves cause said ring to produce torsion vibrations.
7. The apparatus of claim 6, wherein said electric waves cause said ring to vibrate such that standing torsion waves are produced within the liquid.
8. The apparatus of claim 3, wherein said electric waves cause said ring to vibrate along its length.
9. The apparatus of claim 8, wherein said electric waves cause said ring to produce standing longitudinal waves within the liquid.
10. The apparatus of claim 1 wherein said power supply system comprises a pulse power supplier, a MHz power supplier, an amplifier, a controller, and a sensing device.
11. The apparatus of claim 10 wherein said electric waves are in the range of 0.1-20 MHz.
12. The apparatus of claim 10 wherein said power supply system further comprises a KHz power supplier.
13. The apparatus of claim 10, further comprising a mixer to mix electric waves intended to produce thickness vibrations and electric waves intended to produce vibrations along the ring's length.
14. The apparatus of claim 10, wherein said KHz power supplier is adapted to produce electric waves in the range of 20 to 500 KHz.
15. The apparatus of claim 1 wherein the acoustic velocity in the piezo material is gradually reduced to match the acoustic velocity in the liquid to minimize energy loss, when transmitting from the piezo material to the liquid.
16. The apparatus of claim 1, wherein said layer of matching material is made of silicone or plastic.
17. The apparatus of claim 1 wherein said layer of matching material has a thickness in the range of 0.1-10 times the thickness of said piezoceramic ring.
18. The apparatus of claim 1 wherein said layer of matching material comprises of more then one sub-layers made of different plastic materials.
19. The apparatus of claim 1 wherein said layer of matching material has a shape selected from the group consisting of convex, concave, tapered and polygon.
20. The apparatus of claim 1, wherein the thickness of the matching layer depends on one or more of the thickness of the ring and on the applied frequency.
21. The apparatus of claim 1, wherein applying a signal of 1 volt and 1 MHz frequency to the ring, causes a pressure in the middle portion of the liquid filling the ring, wherein the pressure is higher than the pressure in the ring material.
22. The apparatus of claim 3, wherein the apparatus is placed at one of the sites consisting of the connection between at two tubes, at the entrance of a liquid reservoir, the exit of a liquid reservoir, the entrance of a liquid pump and the exit of a liquid pump.
23. The apparatus of claim 3, wherein the apparatus may move in horizontal and vertical axis of a liquid reservoir.
24. The apparatus of claim 3, wherein the apparatus is placed on the outer side of a liquid filter and thereby liquid sterilization and filter cleaning may be performed substantially simultaneously and the vibration of the filter may be adapted to prevent biofilm formation in the filtering system.
25. The apparatus of claim 1 further comprising at least a second ring of vibratable material, wherein said second ring is connected to said first ring of vibratable material.
26. The apparatus of claim 1 comprising: a second piezoceramic ring, wherein the first and the second ring are constructed from the same or different piezo material, wherein the ring dimensions, shape and materials resulting in variable shapes of cavitation area along the ring.
27. An apparatus to substantially sterilizing a liquid comprising:
- at least one container into which a liquid may enter;
- a first ring of vibratable material and having an arbitrary shape and length, said ring at least partially residing inside of said container and having an inner passage through which the liquid may pass;
- a second ring of vibratable material; and
- a power supply system to supply electric waves to said ring.
28. The apparatus of claim 27, wherein said power supply system supplies electric waves at a frequency estimated to be a resonance frequency of a system formed by said ring and the liquid.
29. The apparatus of claim 28, wherein said power supply system supplies electric waves at a frequency estimated to be a resonance frequency of system formed by said ring and liquid within the inner passage of said ring.
30. The apparatus of claim 28, wherein said power supply system supplies electric waves at a frequency estimated to be a resonance frequency of a system formed by said ring and a volume of liquid between the outside of said ring and an inner wall of said container.
31. The apparatus of claim 30, wherein said power supply system also supplies electric waves at a frequency estimated to be a resonance frequency of a system formed by said ring and liquid within the inner passage of said ring.
32. The apparatus of claim 31, wherein said electric waves cause said ring to vibrate along its thickness.
33. The apparatus of claim 31, wherein said electric waves cause the ring to vibrate such that standing thickness waves are produced within the liquid.
34. The apparatus of claim 31, wherein said electric waves cause said ring to produce torsion vibrations.
35. The apparatus of claim 31, wherein said electric waves cause said ring to vibrate such that standing torsion waves are produced within the liquid.
36. The apparatus of claim 29, wherein said electric waves cause said ring to vibrate along its length.
37. The apparatus of claim 31, wherein said electric waves cause said ring to produce standing longitudinal waves within the liquid.
38. The apparatus of claim 31, wherein the liquid is at least partially sterilized due to vibrations produced by said ring.
39. The apparatus of claim 38, further comprising a filter, wherein filter blockage is avoided due to the at least partial sterilization of the liquid.
40. The apparatus of claim 27, wherein the first ring is located at the entrance to the container and the second ring is located at the exit from the container.
41. The apparatus of claim 27, further comprising a second power supply system connected to said second ring of vibratable material.
42. The apparatus of claim 31, wherein a liquid enters the apparatus through an opening on said container and leaves the apparatus through an opening of the inner passage of said ring.
43. The apparatus of claim 31, wherein a liquid enters the apparatus through an opening of the inner passage of said ring and leaves said apparatus through an opening on said container.
44. The apparatus of claim 27, wherein ring has a disk shape having cavities wherein liquid can flow, the cavities having a shape selected from a group consisting of cylindrical, convex, concave, and tapered.
45. A device to substantially sterilize a liquid comprising:
- a piezoceramic ring, said ring being of an arbitrary shape and length, and being attached to an inner diameter of a tubular sterilization container, which has an internal passage with non-flowing or flowing liquid; and
- a power supply system connected to said ring and adapted to supply electric waves to said ring at a frequency estimated to be a resonance frequency of a system formed by said ring and the liquid; thereby focusing acoustic standing waves, wherein a cavitation column is produced in the middle of the ring,
46. A device to substantially sterilize a liquid comprising:
- at least one container into which a liquid may enter;
- a piezoceramic ring having an arbitrary shape and length, the ring disposed inside the container and having an inner passage through which the liquid may pass;
- a power supply system to supply electric waves to the ring, thereby creating a focusing standing waves in the liquid passing through the ring and passing through the container by implying the action of both piezo element sides, wherein a high pressure cavitation column is formed in the middle of the ring, and pressure is created in the liquid passing the inner volume of the ring and the volume between container walls and outer wall of the ring.
Type: Application
Filed: Aug 8, 2008
Publication Date: Nov 27, 2008
Inventors: Jona Zumeris (Nesher), Jacob Levy (Haifa), Zadik Hazan (Ganei Yehuda), Yanina Zumeris (Nesher)
Application Number: 12/188,302
International Classification: B01J 19/08 (20060101);