Abstract:
The invention provides a method of and apparatus for the removal of bacteria, microbes and other cell growth from a body of water by the application of an electromagnetic signal to a section of pipe communicable with the body of water.

Description:
This application is a continuation-in-part application of Ser. No. 09/432,650, filed Apr. 3, 2000 which is a 371 of PCT/AU98/00364, filed May 19, 1998 now abandoned. 
    
    
     TECHNICAL FIELD 
     This invention relates to a method and apparatus for the cleansing of bodies of water such as swimming pools, reservoirs, dams and the like. In particular, it is directed to the removal of bacteria, microbes and other cell growth from water. 
     BACKGROUND ART 
     Large bodies of water such as swimming pools, water catchment areas and similar where the water therein is to be in subsequent contact with people (either by swimming or bathing in the body of water, or by drinking the water) requires cleansing. Although various filters incorporating a filtration medium such as sand can be used to remove particulate matter and other solid debris, the removal of harmful bacteria and other microbiological growth is more difficult. Such bacteria and the like are usually removed by regularly dosing the body of water with a suitable chemical. For example, sodium hypochlorite is commonly added to swimming pools to maintain the dissolved chlorine content of the water at a level which is lethal to any bacteria and the like which is present in the water. In municipal works, where a body of water has to be purified to drinking water standards, a large range of chemicals may be added to the water to purify it. 
     There are a number of disadvantages to these existing methods. Swimming pools usually cannot be used until some period after treatment because the chlorine content necessary to purify the water often irritates the eyes of any person in the pool. In drinking water treatment, there is increasing concern by the community that the deliberate addition fo chemicals into the water supply is harmful in itself. for example, it can lead to allergic reactions in some consumers of the treated water. Therefore, for an increasing number of consumers, it is necessary to filter or otherwise further treat the supplied water before it can be used or consumed. Of course, the use of chemicals and/or further treatment of supplied water all ad to the financial costs of maintaining an acceptable supply of water for use by the community. 
     It is thus a general object of the present invention to overcome, or at least ameliorate, one or more of the above disadvantages. 
     DISCLOSURE OF INVENTION 
     According to the present invention there is provided a method of for the removal of bacteria, microbes and other cell growth from a body of water, said method comprising: 
     applying an electromagnetic field to a section of said pipe or similar conduit communicable with the body of water as water passes therethrough, said electromagnetic field having a frequency or a range of frequencies sufficient to inhibit or remove said bacteria, microbes or other cell growth from said water. 
     The application of the electromagnetic field to said section of pipe can be achieved by magnetizing an element or elements positioned on the wall of the pipe or conduit. 
     Four equally spaced elements can be placed on the wall of the pipe or conduit. 
     The elements can be elongate strips of ferrite material. 
     The ferrite material can be manganese-zinc. 
     The element can be a magnetizable coil. 
     According to a further aspect of the present invention there is provided apparatus for the removal of bacteria, microbes and other cell growth from a body of water, said apparatus comprising: 
     a magnetizable element adapted to be disposed about a section of a pipe communicable with the body of water; 
     means for applying a signal to said magnetizable element to create an electromagnetic field within said pipe, said electromagnetic field having a frequency or a range of frequencies sufficient to inhibit or remove said bacteria, microbes or other cell growth from said water. 
     The magnetizable element can comprise one or more ferrite elements placed on the wall of the section of pipe. 
     The one or more ferrite elements can be manganese-zinc elements. 
     The magnetizable element can be a coil for application of the electromagnetic field to the pipe or conduit the coil being wound about a polyvinyl chloride (PVC) or other non-ferrous former which is located coaxially about the pipe or conduit. 
     An AC voltage can be applied to the magnetizable element to generate the electromagnetic field. 
     The voltage can be 5 volts AC. 
     The frequency of the voltage applied to the magnetizable element can vary to sweep a range of frequencies in the range of 2 KHz to 7 KHz. 
     The signal applied to the magnetizable element can be in the form of a positive going square wave followed by a negative going spike having a variable frequency. 
     The means for generating the signal can comprise first and second square wave oscillators whereby the output of the second oscillator is modulated in frequency by the output of the first oscillator. 
     The signal generating means can include a third square wave oscillator whereby the output of the second oscillator is used to frequency modulate the output of the third square wave oscillator. 
     Amplifier means can be employed for amplifying the output of the third square wave oscillator, the output of the amplifier means is adapted to be connected to the magnetizable element via capacitance means to define the required form of the signal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention and wherein: 
     FIG. 1 illustrates the general nature of the apparatus constructed according to the present invention; 
     FIG. 2 is a circuit diagram of the circuit for generating and applying a signal to a pipe with water flowing therethrough; and 
     FIG. 3 illustrates the application of the apparatus of the invention to a swimming pool; 
     FIG. 4 is a circuit diagram of an alternative circuit for generating and applying a signal to a pipe with water flowing therethrough, and 
     FIG. 5 is a view of a section of pipe from a swimming pool filtration system having apparatus according to the present invention attached thereto, and 
     FIG. 6 is a cross-sectional view of a pipe of a swimming pool installation having robes of the present invention positioned therein, and 
     FIG. 7 is a perspective view of the pipe band in accordance with another aspect of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring firstly to FIG. 1, there is illustrated an apparatus  10  comprising a former  12  manufactured from a non-magnetic non-ferrous material such as a plastics material and preferably a polyvinyl chloride (PVC). Wound about the former  12  are a plurality of turns of wire forming to a coil  13  which is connected to receive a signal from a signal generator  14 . 
     The former  12  is preferably 40 mm in diameter having wound thereon three layers of 0.315 mm insulated copper wire extending approximately 170 mm along the former  12 . The former  12  may be provided with an outer casing to surround the windings or the layers of wire may be provided with a shrink sleeving. 
     The coil is adapted to be connected to a signal generator is housed within a casing  15  provided with an indicator  16  in the form of a light emitting diode (LED) which indicates circuit operation and a further indicator  17  in the form of a light emitting diode (LED) which indicates power supply to the apparatus  10 . Mounted within the casing  15  is a circuit board  18  which carries the components of the signal generating circuit  19  and associated power supply  20 . 
     The power supply  20  includes a bridge rectifier B 1  and capacitor C 1  which are arranged to be connected to an AC supply  21  to provide a pulsating DC voltage at the output of the rectifier B 1  at a frequency in this embodiment of 100 Hz which is then applied to a capacitor C 2  which filters and smooths to supply a DC voltage. This smoothed DC voltage is then applied to a regulator Reg  1  which outputs a fixed DC voltage in this instance 12 volts which in conjunction with capacitor C 3  provides a regulated 12 volt supply. Resistor R 2  applies the voltage output from the bridge B 1  to the externally mounted LED  16  which indicates that power is supplied to the circuit. The resistor R 2  limits the current flowing to the LED  16 . 
     The resistor R 4 , Zener diode Z 1  and capacitor C 4  form a further power supply (VCC), preferably a 5 volts DC supply, to be applied to the signal generator circuit  19 . Alternatively, a further regulator may be used to supply a regulated output for supply to the circuit  19 . 
     The signal generating circuit  19  is primarily formed about a quad and gate Schmitt trigger which in this embodiment comprise a type 4093 CMOS Integrated Circuit U 1  which has four separate gates designated U 1 :A, U 1 :B, U 1 :C and U 1 :D. The gates U 1 :B, U 1 :C and U 1 :D are used as oscillators as described below. 
     The gate U 1 :C forms an oscillator  22  with resistor R 13  and capacitor C 11  whose normal frequency of oscillation as determined by resistor R 13  and capacitor C 11  is 10 Hz. The gate U 1 :D is configured as an oscillator  23  with resistor R 16  and capacitor C 13  which set the normal frequency of oscillation at 7 KHz. Both oscillators  22  and  23  provide a positive going square wave output. The output of the oscillator  23  is connected to the input of the oscillator  22  though resistors R 13  and R 14  and capacitor C 12  which is charged and discharged by the output of the oscillator  23  to apply a modulating signal to the input of the oscillator  22 . The output of the oscillator  22  is thus a modulated positive going square wave of the form illustrated schematically at  24  where frequency varies as determined by the output of the oscillator  23 . The average frequency of this output signal is 3.8 KHz. 
     This output signal is applied via resistor R 12  to the base of a transistor Q 4  and the varying frequency of the signal  24  serves to switch transistor Q 4  on and off at the varying frequency. The purpose of R 12  is to limit the current to the base of transistor Q 4 . 
     The gate U 1 :B in is connected with resistor R 10  and capacitors C 9  and C 10  for form a further oscillator  25  whose output is normally a positive going square wave. As with the oscillators  22  and  23 , the frequency of this oscillator is controlled by the values of its associates resistor and capacitor in this case resistor R 10  and capacitors C 9  and C 10 . The oscillator  25  would normally run at a frequency of 2.6 KHz. The capacitors C 9  and C 10  are connected in series and are of the same value so that the capacitance of the series capacitors C 9  and C 10  is half the total capacitance of the capacitors. This oscillator  25  is modulated by the output signal  24  of the oscillator  22  applied through the transistor Q 4 . The capacitors C 9  and C 10  are connected to the collector of the transistor Q 4  which when switched on and off the shunts the capacitor C 9  to ground at a frequencies determined by the variable frequencies of the output signal  24 . The effect of this switching is to double the capacitance of the series capacitors C 9  and C 10  every time the transistor Q 4  is switch on. This therefore halves the output frequency at output of the oscillator  25 . 
     The output of the oscillator  25  is connected via an R-C circuit formed by resistor R 9  and capacitor C 8  to a Darlington pair of transistors Q 3  and Q 2  which amplify the signal and apply the amplified signal to the positive plate of a capacitor C 6 . The capacitor C 6  isolates DC voltages at the more negative plate and applies the signal to the coil  13  via a connector J 2 . When the coil  13  is connected, the signal passes through the coil  13  and returns to the ground via resistor R 7 . The signal applied to the coil  13  as indicated at  26  comprises a positive going square wave and a negative spike which returns through an exponential curve to zero. 
     The fourth gate U 1 :A of the integrated circuit U 1 , is used as a detector to show that the coil  13  is operating. Resistors R 5  and R 11  form a voltage divider connected to the voltage VCC and applying an input to the gate U 1 :A. The input of the gate U 1 :A is also connected via capacitor C 5  and resistor R 6  to the coil  13 . 
     When the coil  13  is not connected or operating the voltage applied by the voltage divider R 5  and R 11  to the input of the gate U 1 :A causes the output of the gate U 1 :A to be low. When the coil  13  is operating, the input voltage to the gate U 1 :A is lowered by capacitor C 5  AC coupling this voltage to R 6 . When the input voltage goes below the trip point of the Schmitt trigger U 1 :A, the output of the gate U 1 :A goes high thus supplying a voltage to resistor R 3  which is connected to the base of transistor Q 1  and serves to limit the current to the transistor Q 1 . When this current limited voltage is applied to the transistor Q 1  and current limiting resistor R 1  and thus is illuminated when the coil  13  is connected and operating. Thus LED  17  serves as a coil operating indicator. 
     When the coil  13  is removed or not operating the transistor Q 1  is switched off due to an absence of base current and the LED  17  goes out. Both LED  16  and LED  17  are preferably connected externally through connector J 3 . 
     The output to the coil connector or jack J 2  comprises a jumble or range of frequencies generated by the gated U 1 :C and U 1 :D. As stated above both U 1 :C and U 1 :D are connected as separate oscillators with the output of U 1 :D being applied to the input of U 1 :C. The oscillator  22  including gate U 1 :C provides substantially higher frequency than the oscillator circuit  23  which includes gate U 1 :D. Thus if disconnected from each other, the oscillator  22  of U 1 :C will provide a frequency of approximately 10 Hz and that of U 1 :D approximately 7 KHz. The combined circuit generates a sweep of frequencies usually in the range of 1 KHz to 7 KHz. 
     It is however within the scope of the present invention to provide an oscillator circuit which provides a single frequency output or a range of frequencies beyond the above range for application to the coil. Appropriate frequency selection is made in accordance with the nature of the cell growth and/or the quality of water flowing through the pipe. 
     In use and as shown in FIG. 3, the apparatus of the invention may be suitably applied to an installation  27  representing a swimming pool. The former  12  carrying the coil  13  is located about the pipe  12  and is placed in the pool below the surface of the water. The signal generator  14  housed in the housing  15  is mounted in any suitable location and connected to the coil  13  through the wires  32 . 
     With respect to FIG. 4 of the drawings, and in accordance with a further aspect of the present invention a signal is primarily generated from a single-ship microcontroller  22  which in this embodiment comprises a type PIC 16C73A microcontroller. The 4.00 MHZ crystal X 1  and two 15 pF capacitors C 17  and C 18  form the base frequency oscillator for the microcontroller. C 14  and C 15  serve as by-pass capacitors that stabilize the power supply to the microcontroller. The DS1233-10 reset unit ensures the microcontroller starts successfully on every power up. 
     The microcontroller generates an internal square wave signal at 10 Hz modulated at 7 kHz producing a signal with an average frequency of 3.8 kHz. This signal is used to vary the frequency of a third oscillator, the third oscillator normally running at a frequency of 2.6 kHz. The effect of the signal applied to this third oscillator is that it will have the frequency of the third oscillator every time the signal goes high and return the third oscillator to its normal frequency when the signal goes low. The output of this third oscillator RCO (CDRV) is applied via an RO-C circuit formed by resistor R 9  and capacitor C 8  to a Darlington pair of transistors Q 3  and Q 2  which amplify the signal to the positive plate of a capacitor C 6 . The capacitor C 6  isolates DC voltages at the more negative plate and applies the signal to the coil  13  via a connector J 2 . When the coil  13  is connected, the signal passes through the coil  13  and returns to ground via resistor R 7 . The signal applied to the coil  13  as indicated at  26  comprises a positive going square wave and a negative spike which returns through an exponential curve to zero. Resistors R 5  and R 11  form a voltage divider connected to the voltage VCC and applying an input to the microcontroller at RBO (CFB). This input is also connected via capacitor C 5  and resistor R 6  to the coil  13  and is used as a detector to show that the coil  13  is operating. 
     When the coil  13  is not connected or operating the voltage applied by the voltage divider R 5  and R 11  to the input of the microcontroller is low and the microcontroller turns LED  17  off. If the coil  13  is connected and operating the input voltage goes high and the microcontroller turns LED  17  on. Thus LED  17  serves as a coil operating indicator. The base frequencies for operation are stored in a serial Electrically Erasable Programmable Read Only Memory (EEPROM) U 5  which in this case is a PIC24CO4AP. These frequencies may be changed to suit a particular application by means of adjusting via two push-buttons PB 1  and PB 2  and displays DSP 1  and DSP 2 . These pushbuttons and displays are preferably located on an additional board that is able to plug into the main system board, thereby limiting the ability to change frequencies to only those that are authorized to do so. 
     Transistors Q 1  and Q 5  serve to multiplex the display of numbers. A number display may be applied to DSP 1  only by the microcontroller turning on Q 1  and turning off Q 5 . To display a number on DSP 2  the microcontroller turns on Q 5  and turns off Q 1 . By alternating this process at approximately 60 times a second, the human eye will not be able to detect any amount of flickering due to the displays repeatedly being switched on and off. 
     FIGS. 5 to  7  of the drawings illustrates a section of piping in a swimming pool installation to which probes of an apparatus according to another aspect of the present invention are attached. A plurality of probes  30 ′ having electrical connection to the output of the signal generating apparatus of FIG. 4 are positioned on the outer surface of a section of pipe  31 ′. The probes  30 ′ may be in the form of elongate bars of a ferrite material. Our trials to date have indicated that manganese-zinc supplied by NEOSID AUST. PTY LIMITED and identified by the code F 8  is a suitable material. Good results have been achieved by using one to five probes  30 ′. According to data provided by NEOSID AUST. PTY LIMITED their F 8  coded ferrite material has an optimum frequency range of between 0.1 and 0.5 MHz. A convenient manner of attaching the probes is to enclose individual probes within equally spaced pockets  32 ′ of a band  33 ′. The band  33 ′ can be mounted on a section of pipe and secured using Velcro or like attachments. 
     The probes  30 ′ are each wound with a coil and separately electrically connected to the output of the signal generating apparatus. 
     When two or more probes are fixed to a pipe multiple overlapping frequencies can be applied to fluid within a pipe. Such an arrangement provides the flexibility to treat the whole of a body of water in pipes of varying sizes and overcomes the disadvantage of a treatment system using a single coil wound on a pipe or sleeve in which inner portions of the body of water may not be reached or affected. 
     The use of the method and apparatus of the present invention should thus at least reduce the costs of maintaining a healthy water supply by means which are both more environmental friendly and more acceptable to the general community. 
     It will be appreciated that the above examples are illustrative only of the present invention and that modifications and alterations can be made thereto without departing from the inventive concept as hereinbefore described.