HK1207041B - System and method for prevention of adhesion of organisms in water to a substrate in contact with water - Google Patents

Description

System and method for preventing adhesion of aquatic organisms to substrates in contact with water

Technical Field

The present invention relates generally to the field of preventing organisms in water from attaching themselves to substrates exposed to water, and more particularly to a system and method for preventing organisms from adhering to substrates in contact with water, such as vessels, ships, pipelines, and the like, by using avalanche currents induced by electromagnetic waves having time-varying frequency signals.

Background

Biofouling or biological fouling is the undesirable deposition, attachment and growth of microorganisms, plants, algae and/or animals on the surface of an underwater vessel. Biofouling caused by marine organisms on the surface of an underwater vessel is a well-known problem. If the growth build-up of marine organisms on the vessel is not controlled, the build-up can substantially reduce the speed of the vessel, increase fuel consumption and block the seawater cooling lines or any seawater intake and discharge lines. In addition to marine applications, biofouling control is also essential for seawater cooling systems, such as power station seawater cooling water intake and condenser cooling systems.

In addition to biofouling, it is desirable to prevent the intrusion of marine organisms into seawater cooling systems during installation in many industrial plants. For example, a large number of shrimp intruding into the generator cooling system may clog the screens or ports and cause the power plant to shut down.

Various methods have been developed to address the above problems to remove or prevent the accumulation of marine organisms. One of these methods is the use of toxic chemicals, coatings and metal ionization to control biofouling, but this method is harmful to the environment. Another method is electrical methods to control or prevent adhesion of organisms. These electrical methods are known, for example, from WO2004/071863, US 6,209,472 and JP 2004183018.

WO2004/071863 discloses an anti-fouling and anti-fouling system for aquatic organisms, the system comprising one or more anodes and cathodes mounted at a portion of the vessel structure and at least one pulse generator electrically connected to the anodes and cathodes. The biofouling effect is obtained by generating a high or low electric field between the anode and the cathode and relies on the current-carrying ions flowing through the water across the two electrodes. The system of this patent application has the major disadvantage that the biofouling effect cannot be achieved outside the space between the cathode and the anode.

In WO2004/071863a, a pulse generator generates a DC pulsed current which is discharged from an anode immersed in water to a cathode via an electrolyte such as seawater. Likewise, chlorine and hypochlorite are generated at or near the electrode surface in the water, and the biocidal effect of biological organisms is actually achieved primarily by the environmentally harmful chlorination effect produced by the DC pulsed wave current, rather than by the pulsed wave shock or killing effect altogether.

JP2004183018 relates to an anti-fouling device which achieves an electrochemical anti-fouling effect by using a control current between a conductive substrate and a counter electrode constant. The device is essentially a DC impressed current system to move the surface of the structure to the electrolyte potential to control the growth and attachment of organisms, with the anodes and cathodes alternating periodically. Similar to WO2004/071863A, when DC current is applied to water, chlorine or hypochlorite is generated and this process becomes an environmentally unfriendly chemical disinfection process. It should be noted that other chemicals or coatings are also included in the patent application.

US 6,209,472 discloses a system for inhibiting the growth of marine organisms on an underwater surface, the system comprising a current generator which causes a current to flow near the underwater surface, a power source, such as a battery, for providing power to the current generator, wherein the current flows from the underwater surface through water surrounding the surface or water contacting the surface, and a point of ground potential. Further, the system uses a pulsed DC generator to generate chlorine or hypochlorite to control organic growth.

The above anti-fouling methods and systems use Direct Current (DC) or DC pulsed waves or DC components. When a DC pulse or DC current is released from an electrode in an electrolyte (e.g., seawater), an active substance such as chlorine gas, hydroxyl ions, hypochlorite or other toxic side-effects may be generated. The production of all these active substances is virtually no different from the environmentally harmful chemical-based methods such as electron-chlorination. According to International Maritime Organization (IMO) regulations, the production of such substances is considered undesirable, and the water treated by these methods and systems must be subjected to additional evaluation procedures, including environmental impact evaluations, to ensure that negative impacts are kept to a minimum.

Another disadvantage of the above-described methods and systems is that they are based on the conventional DC electrolysis concept to follow ohm's law, which cannot be applied to AC circuits. That is, the current flowing through the circuit loop including the current path in water is always constant and is determined by the total resistance. If the resistance is constant, the current will remain constant unless the drive voltage changes. According to ohm's law, current flow in an electrolyte such as water is characterized by "current flows through the lowest resistance and shortest path" and exhibits a current sink and current source potential distribution pattern. No electrons flow in the water and all current flow in the water is via ionic conduction. When this current flow follows the conventional current flow, there are many blind spots or zones in the electrolyte where the conventional ohmic or ionic current cannot reach. Typically, these blind spots are regions located outside the current well-current source potential field.

Fig. 1 shows a schematic diagram of an anti-fouling arrangement based on a conventional DC assembly. As shown, an anode 1 and a cathode 2 are immersed in the water in spaced apart relation, and a positive and negative pole of a DC or DC pulse source 3 is electrically coupled to the anode 1 and cathode 2, respectively, to generate an electric field 4 between the anode 1 and cathode 2. A conventional DC or DC pulsed current flows in the electric field 4 between the anode 1 and the cathode 2. In fig. 1, it is clear that the conventional DC or DC pulsed current cannot reach the regions 51, 52, 53 and 54 far from the electric field between the anode and the cathode. If such dead zones are present, bacteria and microorganisms can survive and grow well in these dead zones, and biofouling control can be less effective.

The main challenge has been to develop alternative techniques for galvanic anti-fouling methods and systems to prevent fouling on underwater substrates such as ship hulls or substrates in contact with water such as platform structures, seawater cooling water systems, buoys, etc. For this purpose, there is a need for a device and a method for preventing the adhesion of organisms in water to a substrate in contact with water, which are structurally very simple, relatively inexpensive and more environmentally friendly, do not leach out toxins, whether the substrate is in a stationary state or in motion, but allow an efficient control or prevention of the adhesion of unnecessary organisms.

Disclosure of Invention

The present invention has been developed to meet the above-mentioned needs, and therefore has the main object: a system for preventing organisms in water from adhering to a substrate in contact with the water is provided, which is environmentally friendly and does not immerse toxins in the water.

It is another object of the present invention to provide a system for preventing organisms in water from adhering to substrates in contact with the water that is much more economical and convenient to use.

It is a further object of the present invention to provide a system for preventing organisms in water from adhering to a substrate in contact with the water which allows for efficient control or prevention of attachment of unwanted organisms.

These and other objects and advantages of the present invention are met by providing a system for preventing organisms in water from adhering to a substrate in contact with the water, wherein the substrate and the water flowing around the substrate together form a treatment zone, the system comprising:

a generator for generating an electromagnetic wave having a time-varying frequency, said generator having at least two output terminals, one of which is electrically connected to the first excitation site of the treatment zone;

an avalanche current suppressor having one terminal electrically connected to the other of the output terminals of the generator and the other terminal electrically connected to the second excitation site of the processing region; and

a power supply connected to the generator for applying a selected voltage to the generator,

wherein application of a voltage causes the generator to be triggered to generate a time varying frequency electromagnetic wave capable of inducing an avalanche current in the water and/or on the surface of the substrate to shock or kill organisms.

According to the invention, the substrate can be made of an electrically conductive or non-conductive material. For non-conductive materials, if the excitation sites are positioned on a non-conductive substrate, one or more metal elements may be disposed at the excitation sites for electrical connection with the generator or suppressor. Alternatively, the electromagnetic wave emitter may be used for the same purpose as the metal member.

The position of the first or second excitation site may be varied according to actual needs and requirements. The two excitation sites may be arranged in spaced relation on the same surface of the substrate or on two different surfaces of the substrate. It is possible that one of the first excitation site or the second excitation site is positioned on the surface of the substrate and the other is positioned in the water.

Preferably, an emitter may be provided at one or each of the first and second excitation sites, and the first and second excitation sites are electrically connected to the generator and suppressor by the emitter.

In the case of a matrix of non-conductive material, the treated region is preferably completely or partially enclosed to enhance the avalanche wave current flux density.

Advantageously, the frequency of the time-varying frequency electromagnetic waves is between about 100Hz and about 1MHz, preferably between about 100Hz and about 200 kHz. The electromagnetic waves preferably have a scanning frequency between about 1Hz and about 1 kHz.

The avalanche current suppressor 130 is arranged to suppress or control the avalanche current which grows exponentially. The suppressor may be selected from digital or analog RLC circuit, inductive circuit, capacitive circuit, LC circuit, RL circuit or RC circuit designs to accommodate different load requirements for different applications. One example of a suppressor is a series RLC circuit comprising a resistor (R), an inductor (L) and a capacitor (C), the characteristics of which are that the magnitude of the current is a function of frequency and that the current reaches a maximum at the resonant frequency, thereby achieving the effect of limiting the amount of current in the treatment zone defined by the substrate and the water flowing around the substrate.

The voltage triggering the generation of the avalanche current can be very small. In one embodiment of the invention, the power supply supplies a peak-to-peak voltage of about 24V to 200V as the trigger voltage for the electromagnetic wave generator.

Another aspect of the invention is to provide a method for preventing organisms in water from adhering to a substrate in contact with the water, wherein the substrate and water flowing around the substrate together form a treated region, the method comprising the steps of:

a generator is provided for generating an electromagnetic wave having a time-varying frequency,

subjecting the treatment area to the generated time varying frequency electromagnetic waves, wherein a selected voltage is applied to the generator such that the generator is triggered to generate time varying frequency electromagnetic waves capable of inducing avalanche currents in the water and/or on the surface of the substrate to shock or kill organisms,

suppressing avalanche current flow through the processing region.

Unlike conventional DC component-based systems to prevent organism adhesion in confined water, the essence of the present invention is to use avalanche current, a self-contained fast gain current pulse, generated by time varying electromagnetic waves on the surface of a substrate or in water. Avalanche current does not depend on the ions carrying the current in the water, but rather, avalanche current is the combined result of electrons and charged particle bombardment that occur in water. It has been found that the receptor sites on the cell membrane of an organism are thermally or physiologically undesirable for electron avalanches and exit atoms in the matrix, thereby preventing microorganisms, algae, biofilms and other substances from attaching to the surface of the matrix. Thus, an anti-fouling effect of the organisms is achieved without causing any harm to the environmental ecological conditions.

Conventional DC assembly based systems are characterized by a cathode and anode arrangement connected to positive and negative terminals of a power supply. In contrast, in the present invention, there is no electrode arrangement, and the generated electromagnetic wave is a pure AC wave, and the electromagnetic wave generator can be directly connected to the same metal sheet without causing a problem of short circuit.

For a better understanding of the present invention, reference is made to the following detailed description of the invention and its embodiments, taken in conjunction with the accompanying drawings.

Drawings

Fig. 1 is a schematic diagram of an exemplary arrangement known in the prior art.

FIG. 2 is a schematic view of a system for preventing marine organisms from adhering to a substrate in contact with seawater, the system constructed in accordance with a first embodiment of the present invention.

FIG. 3 is a schematic view of a system for preventing marine organisms from adhering to a substrate in contact with seawater, the system constructed in accordance with a second embodiment of the present invention.

FIG. 4 is a schematic view of a system for preventing marine organisms from adhering to a substrate in contact with seawater, the system constructed in accordance with a third embodiment of the present invention.

FIG. 5 is a schematic view of a system for preventing marine organisms from adhering to a substrate in contact with seawater, the system constructed in accordance with a fourth embodiment of the present invention.

FIG. 6 is a schematic view of a system for preventing marine organisms from adhering to a substrate in contact with seawater, the system constructed in accordance with a fifth embodiment of the present invention.

Detailed Description

While the invention has been shown and described in its preferred embodiments, the system for preventing adhesion of organisms in water to a substrate in contact with the water can be made in a number of different configurations, sizes, forms and materials.

Conventionally, it is understood that avalanche current only occurs in a gas plasma discharge or vacuum that is prone to electron-hole pairs, and avalanche current does not occur in water or on metal surfaces. The present invention is based on the discovery that: the excitation of water or metal by low frequency electromagnetic waves using time varying pulses can generate avalanche currents in water as well as in metal. Electrons and charged particles are bombarded in an "avalanche" manner by creating an avalanche current in water, without following the "conventional current sink and source" potential distribution and current flow characteristics. The characteristics of electrons and charged particles are similar to electron bombardment in fluorescent tubes. In order to control and limit the avalanche current through water and the substrate, an avalanche current suppressor therefore needs to be incorporated into the present invention.

The avalanche current will reach the fine gaps and corners in the water mass, or will reach the surface of the substrate, due to the random bombardment of electrons and charged particles. As the avalanche current travels throughout the body of water, the avalanche current can effectively kill or shock organisms in the water, including reaching blind spots or zones in the water that conventional DC component-based systems cannot reach.

When an avalanche current occurs on the surface of the present invention, the surface is "energized" or "heated" and prevents the attachment or adhesion of organisms. The avalanche current effect can be seen on the surface of the substrate and in the water throughout the treatment zone, with the result that the environment is not favorable for the organisms in the parts of the substrate that come into contact with the water. Chemicals or active substances are not introduced into the water.

It has also been found that avalanche current can jump back and forth in a fully enclosed non-conductive chamber (e.g., in a plastic can) or a partially enclosed non-conductive chamber (e.g., a non-metallic can with an open end). Thereby, the measured wave voltage and frequency are amplified with characteristics similar to those of high frequency electromagnetic waves generated from a magnetron in a microwave oven. Amplification of frequency and voltage is beneficial for killing or controlling the growth of organisms in water.

The salient feature of the invention is that avalanche current is induced in water and on the surface of a substrate by time-varying pulsed low-frequency alternating electromagnetic waves. The time-varying pulse low-frequency wave does not include a direct current element, so that unnecessary DC pulse waves or DC electrolysis including generation of chlorine gas or generation of active substances does not occur. In fact, DC pulsed waves or DC electrolysis have other disadvantages: biofilm and hard chemical scales formed at the cathode surface to reduce the active cathode surface area and increase diffusion resistance for oxygen, which has many negative effects on biological sludge and organism control. In the present invention, the formation of scales and biofilm does not occur because time-varying pulsed low frequency electromagnetic waves are used, and it has also been found that the Total Residual Oxygen (TRO) content and the formation of disinfection side products (DBP) in the water treated by the present invention are not increased and have no harmful effect on the environment. This allows to eliminate the necessity of accepting an active substance evaluation approved by the IMO type.

For clarity and convenience, "marine organisms" in seawater are considered herein as an example of organisms that attach to substrates that come into contact with seawater. It should be understood that organisms in any other electrolyte are suitable.

Referring now to the figures, FIG. 2 provides a system 100 constructed in accordance with a first embodiment of the present invention. In this embodiment, the system 100 includes a power supply unit 110, a generator 120 to generate electromagnetic waves having a time-varying frequency, an avalanche current suppressor 130, and a metal pipe 140 such as a steel pipe, into which the seawater flows 140. The metal pipe 140, the seawater flowing into the pipe, and the water flowing out of but around the pipe constitute a treatment zone which is subjected to an electromagnetic field having a time-varying frequency.

The power supply unit 110 is electrically connected to the generator 120. AC power is used in the power supply unit 110. The power supply unit 110 supplies an AC voltage to trigger the generation of an avalanche current in the water and/or on the surface of the tube 140 to resist fouling. The power supply unit 110 preferably supplies the generator 120 with a peak-to-peak voltage that is between about 24V and about 200V depending on the actual application. The trigger voltage can be very small. For submerged steel structures in seawater, a minimum peak-to-peak voltage of about 24V is required to trigger the generation of avalanche current. It will be appreciated that the higher the trigger voltage, the stronger the electromagnetic intensity output by the generator to trigger the avalanche current.

The generator 120 may have any type of device known in the art that is capable of generating time-varying frequency electromagnetic waves. The generator is, for example, a circuit board, a console card or a ferrite core antenna, wherein a coil is wound around the antenna. The generator 120 has two output terminals 122, 124, and the terminal 122 is electrically connected to an avalanche current suppressor 130.

To control different organisms in the water, a large range of frequencies is required, as different types of organisms respond to different frequency ranges and current intensities. Preferably, the time-varying frequency of the electromagnetic waves used in the present invention is in the range of 100Hz to 1MHz, preferably 100Hz to 200kHz, while the scanning frequency is between about 1Hz to 1 kHz. The waveform of the time-varying frequency electromagnetic wave may be rectangular, triangular, sinusoidal, or other form.

The avalanche current suppressor 130 is arranged to suppress an avalanche current that increases exponentially. A first terminal of the suppressor 130 is electrically connected to the generator output terminal 122 and a second terminal of the suppressor 130 is connected to the tube 140. The suppressor 130 of the present invention acts like a ballast used in a fluorescent tube to limit the current passing through the tube where electrons travel from one end to the other in a vacuum to produce an avalanche effect, which is shown by the exponential increase in current in the tube. The suppressor 130 may be a digital or analog RLC circuit, L circuit, C circuit, LC circuit, RL circuit, or RC circuit to accommodate different load requirements for different applications. In this embodiment, the suppressor is a series RLC circuit characterized in that the magnitude of the current is a function of frequency and the current reaches a maximum at the resonant frequency, thereby achieving the effect of limiting the amount of current in the processing region.

As shown in fig. 2, the second terminal of the suppressor 130 and the output terminal of the generator 120 are connected to the first excitation site 160 and the second excitation site 150, respectively, which are located in spaced relation on the same wall surface of the tube 140, so that the problem of short-circuiting is not caused. When a trigger voltage is applied to the generator, a time-varying pulsed low frequency electromagnetic wave is generated and travels on the wall surface of the tube 140 and also in the water to induce an avalanche current. It should be understood that no gas discharge plasma phenomenon occurs in the metal substance and water at this time, and the avalanche effect is reflected in the increase in the wave current. Therefore, the avalanche current suppressor 130 is required to stabilize and limit the current.

After the avalanche current is induced, electrons and charged particles in the tube and in the water will be bombarded in an avalanche manner, so that the current will be transported in all directions in the treatment zone. Electromagnetic waves may travel on the surface of the metal tube by the skin effect due to high frequencies, which facilitates the avalanche effect. If an electromagnetic wave travels over the surface, the surface becomes a "hot plate" for the organic, which will choose to remain in the water rather than attach to the surface. Thereby, the entire tube 140 is completely subjected to the avalanche current treatment, and marine organisms are effectively prevented from adhering to the tube. This is unlike DC module based systems, where current flows only between the anode and cathode, and no current flows outside the electrolyte space of the anode and cathode.

To excite the avalanche current, the output terminals of the generator can be connected in various ways to the tube or to the water. Fig. 3 and 4 show second and third exemplary variants of the arrangement in fig. 2.

In fig. 3, the first excitation site 160 and the second excitation site 150 are positioned on two opposing surfaces. In this embodiment, the two output terminals 124, 122 of the generator 120 are connected to the first excitation site 160 and the second excitation site 150 via electromagnetic wave emitters 170, the electromagnetic wave emitters 170 being received in through holes extending through the tube wall at the first excitation site and the second excitation site. The electromagnetic wave emitter 170 can enhance the propagation of electromagnetic waves along the surface of the pipe and in the water. When an avalanche current is emitted from the emitter pair 170, a more intense avalanche effect will occur and the voltage of the water to the tube will increase by a few volts. To guide the avalanche current, an electrical isolation material 172 may be filled between the emitter 170 and the hole. The isolation material 172 allows time varying frequency electromagnetic waves and avalanche currents to propagate from the emitter to and along the metal surface by the skin effect.

In fig. 4, the output terminal 122 of the generator 120 is connected to water by an electromagnetic wave transmitter 170. As shown, the emitter 170 is positioned in the water in the pipe 140. This arrangement can also produce the avalanche effect shown in figures 1 and 2.

Referring now to fig. 5, there is shown a system 200 constructed in accordance with a fourth embodiment of the invention. In this embodiment, the substrate to be treated is a hydrocyclone housing 241 made of a metallic material. Similar to the first embodiment discussed above, the system 200 comprises a power supply unit 210, a generator 220 to generate electromagnetic waves with a time varying frequency, an avalanche current suppressor 230 and a hydrocyclone 240 containing seawater. The hydrocyclone housing 241 and seawater constitute a treatment zone which is subjected to an electromagnetic field having a time varying frequency.

The descriptions of the power supply unit 210, the generator 220, and the suppressor 230 may refer to the corresponding units described above in the first embodiment, and the descriptions thereof are omitted here. As shown, two output terminals of the generator 220 are connected to the housing 241 at the top and bottom of the housing 241 to induce an avalanche current flowing in the water and along the surface of the housing 241. The avalanche current effectively prevents marine organisms contained in the water within the hydrocyclone from attaching to the housing 241.

Fig. 6 shows a system 300 constructed in accordance with a fifth embodiment of the invention. In this embodiment, the system 300 includes a power supply unit 310, a generator 320 to generate electromagnetic waves having a time-varying frequency, an avalanche current suppressor 330, and a non-metallic tube 340, such as a plastic tube. The arrangement in this embodiment is substantially the same as that shown in the first embodiment described above, but differs from the first embodiment in that the tube is made of a non-conductive, non-metallic material, and a metallic filter 380 is provided across the cross-section of the tube. To energize the plastic tube 340, the output terminals of the generator 320 may be connected to a metal filter 380 as shown in fig. 6. Multiple metal filters may be used to increase efficiency.

Instead of a metal filter, an electromagnetic emitter may be positioned in plastic tube 340 to induce an avalanche current on the surface of the tube and in the water, which is within the ability of one of ordinary skill in the art.

In this embodiment, avalanche current will travel in the water because the plastic tube 340 is unable to provide a conductive path along which current flows. In order to produce a significant electric shock or killing effect on the organisms, it is advantageous to completely or partially enclose the entire structure to reduce the volume of water to a certain extent. In the closed structure, the avalanche current jumps back and forth so that the current is intensified. All organisms in the closed structure are subjected to avalanche current treatment and prevented from adhering to the surface of the plastic tube.

As can be seen, the present invention treats both conductive and non-conductive substrates in two ways. In the case of a conductive matrix, the time-varying frequency electromagnetic waves will travel simultaneously in the water and along the conductive path provided by the conductive matrix. The induced avalanche current is strong enough to shock and kill any living organisms in the water (also due to the skin effect). Depending on the substrate thickness and frequency range, the emitters may or may not be provided and the excitation sites may be varied.

In the case of a non-conductive substrate, time-varying frequency electromagnetic waves will travel in the water because there is no conductive path available. If the excitation site is located in an inexhaustible open sea, the avalanche wave current flux density may be weakened when the electromagnetic wave is far from the excitation site to effectively control the attachment of organisms in such a situation, preferably completely or partially enclosing the non-conductive matrix.

In the case of a conductive substrate that is well covered with, for example, a rubber gasket, the substrate will be treated as a non-conductive substrate. In the case of a conductive substrate covered with a porous non-conductive coating, the substrate will be treated by the method used for the combination of the conductive substrate and the non-conductive substrate.

The present invention thus provides a device and method for preventing organisms from adhering to substrates in contact with water that is very simple, relatively inexpensive and more environmentally friendly, does not leach out toxins, and provides a highly effective anti-fouling effect. In this invention, the avalanche current effect is expected to be able to propagate throughout the entire body of water and the surface of the substrate.

Although the embodiments illustrated herein are meant to be exemplary arrangements to prevent organisms in water from adhering to substrates in contact with the water, it should be understood by one of ordinary skill in the art that the present invention is not limited to the illustrated embodiments. Other possible variations and modifications will be envisaged by the person skilled in the art without departing from the scope of the invention by the general knowledge of the person skilled in the art, but such variations and modifications should fall within the scope of the invention.

Claims (23)

1. A system for preventing adhesion of organisms in water to a substrate in contact with the water, wherein the substrate and water flowing around the substrate together form a treatment zone, the system comprising:

a generator for generating an electromagnetic wave having a time-varying frequency, the generator having at least two output terminals, one of which is electrically connected to a first excitation site of the treatment zone;

an avalanche current suppressor having one terminal electrically connected to the other of the output terminals of the generator and the other terminal electrically connected to a second excitation site of the processing region; and

a power source connected to the generator for applying a selected voltage to the generator,

wherein the voltage is applied to cause the generator to be triggered to generate the electromagnetic wave having a time-varying frequency capable of inducing an avalanche current in the water and/or on the surface of the substrate to shock or kill organisms.

2. The system of claim 1, wherein the substrate is made of an electrically conductive material.

3. The system of claim 1, wherein the substrate is made of a non-conductive material and one or more metal elements are disposed at the excitation site to electrically connect with the generator or the avalanche current suppressor if the corresponding excitation site is positioned on the non-conductive substrate.

4. The system of claim 3, wherein the metal element is formed as a filter or screen across a cross-section of the substrate.

5. The system of any of claims 1 to 4, wherein the first and second excitation sites are positioned in spaced relation on the same surface of the substrate.

6. The system of any of claims 1 to 4, wherein the first and second excitation sites are positioned on two different surfaces of the substrate.

7. A system as claimed in any one of claims 1 to 4, wherein one of the first and second excitation sites is located on a surface of the substrate and the other is located in the water.

8. A system as claimed in any one of claims 1 to 4, wherein a transmitter is provided at one or each of the first and second excitation sites, the first and second excitation sites being electrically connected to the generator and the avalanche current suppressor, respectively, by way of the transmitter.

9. A system as claimed in any one of claims 1 to 4, wherein electrically isolating material is provided to surround the first and second excitation sites.

10. The system of claim 1, wherein said substrate is made of an electrically non-conductive material and if said first and/or second excitation sites are positioned on the electrically non-conductive substrate, an emitter is provided at the respective excitation site for electrical connection with said generator or said avalanche current suppressor.

11. The system of claim 1, wherein the substrate is made of an electrically non-conductive material and the treatment zone is completely or partially enclosed.

12. The system of claim 1, wherein the frequency of the electromagnetic wave having a time-varying frequency is between 100Hz and 1 MHz.

13. The system of claim 12, wherein the frequency of the electromagnetic wave having a time-varying frequency is between 100Hz and 200 kHz.

14. The system of claim 1, wherein the electromagnetic wave having a time-varying frequency has a sweep frequency between 1Hz and 1 kHz.

15. The system of claim 1, wherein the avalanche current suppressor is selected from an RLC circuit, an inductive circuit, a capacitive circuit, an LC circuit, an RL circuit, and an RC circuit.

16. The system of claim 1, wherein the power supply supplies the generator with a peak-to-peak voltage of 24V to 200V as the trigger voltage.

17. A method for preventing adhesion of organisms in water to a substrate in contact with the water, wherein the substrate and water flowing around the substrate together form a treatment zone, the method comprising:

a generator is provided for generating an electromagnetic wave having a time-varying frequency,

subjecting the treatment zone to the generated electromagnetic waves having a time-varying frequency, wherein a selected voltage is applied to the generator such that triggering the generator generates the electromagnetic waves having a time-varying frequency that can induce an avalanche current in the water and/or on the surface of the substrate to shock or kill organisms, and

suppressing the avalanche current through the processing region.

18. The method of claim 17, wherein the substrate is made of an electrically non-conductive material and the treatment zone is completely or partially enclosed.

19. The method of claim 17, wherein the frequency of the electromagnetic wave having a time-varying frequency is between 100Hz and 1 MHz.

20. The method of claim 19, wherein the frequency of the electromagnetic wave having a time-varying frequency is between 100Hz and 200 kHz.

21. The method of claim 17, wherein the electromagnetic wave having a time-varying frequency has a sweep frequency between 1Hz and 1 kHz.

22. The method of claim 17, wherein the avalanche current suppressor is selected from an RLC circuit, an inductive circuit, a capacitive circuit, an LC circuit, an RL circuit, and an RC circuit.

23. The method of claim 17, wherein the power supply supplies the generator with a peak-to-peak voltage of 24V to 200V as the trigger voltage.