AU2006265773C1 - Water treatment apparatus - Google Patents

Abstract

A portable apparatus for treating polluted water by electrocoagulation. The apparatus comprising at least two electrodes (1,2). The apparatus also includes a housing (4), electrically isolated from the at least two electrodes (1,2), to which the at least two electrodes (1,2) are fixed spaced apart from one another. When the at least two second electrodes (1,2) are at least partly submerged in the polluted water and provided with an electrical potential, one of the at least two electrodes (2) is sacrificial so as to provide ions to the polluted water.

Description

WO 2007/003003 PCT/AU2006/000934 WATER TREATMENT APPARATUS Field of the invention The present invention relates generally to a water treatment apparatus and, more 5 particularly, to a portable apparatus for treating polluted water by electrocoagulation. The invention has been primarily developed for use in cleaning water to potable standard, and will be described hereinafter with reference to this application. However, the invention is not limited to this particular use and, for example, is also suitable for cleaning 10 small volumes of industrially polluted water for compliant discharge. Background There are many situations where natural water supplies contain pollutants, such as clay, animal waste, industrial pollution and other sources of pollutants that either make the 15 water appear unsafe for drinking or unpalatable. These include remote communities in isolated regions and hikers, travellers, campers and similar travelling in remote regions. Taking a full supply of safe drinking water is both costly and bulky. There are also many situations where natural or man made disasters cause damage or 20 destruction to the reticulated water supply such that, although there is an adequate amount of water available, it is generally polluted with sewer/septic overflow, decaying organic matter or other pollutants. Drinking such water could result in consumers becoming infected with cholera or any number of other water borne diseases. Not drinking such water would result in rapid death due to dehydration. 25 There are a number of known devices which seek to address the above problem, including: chlorine tablets (to disinfect the water); filters to remove the pollutant; and others. A disadvantage of chlorine is, even if it is added to the water, the resultant unappealing taste of the water means that it is not liked by the populace. Storing chlorine 30 tablets is also difficult and they are not easily available for many situations. A disadvantage of many emergency filters is that they can only be used for short periods of time before they become clogged. A disadvantage of reusable filters that can remove most pollutants is that they can be expensive. Also, filters do not remove some pollutants like mercury, lead, arsenate and similar. Further, many so-called "emergency" filters do WO 2007/003003 PCT/AU2006/000934 -2 not remove some of the smaller clay particles and the filtered water still thus appears unpalatable to drink, even though it is generally safe. It is an object of the present invention to substantially overcome, or at least ameliorate, 5 one or more of the above disadvantages. By way of further background, the process of coagulation has been successfully used in the industry to achieve good water treatment results. In that process, trivalent metals, usually aluminium and/or iron, are used for cleaning water. Their ions, Al** and Fe** 10 respectively, are added to polluted water in the form of alum (aluminium sulphate) or ferric chloride. The metal ions bind with the pollutant and assist in removing the pollutant from the water, either causing it to sink to the bottom (settling ponds), float to the top (dissolved air flotation) or increase the size of the pollutants and allow them to be more easily filtered. Irrespective of the mechanism of removal, the use of these ions is 15 wide spread in the water treatment industry. Chemical treatment of water is often not viable because it adds to the salinity of the water and the chemicals are quite hazardous. In the process known as electrocoagulation, those same ions are added to the water electrolytically. In that process, sacrificial electrodes are placed in the polluted water and 20 a voltage applied to them. This causes an electric current to flow between the electrodes, which releases some of the anode metal into solution via the reactions: Al - 3e- gives Al** (1 and Fe - 3 e- gives Fe.. (2 25 The electricity also produces a reaction at the cathode when the electrons leave the cathode and go into the water, which reaction is given by: 2 H 2 0 - 4e- gives 2(OH)- + 2112 (3 30 This reaction liberates hydrogen gas. In view of the complexities of the reactions and the power requirements to treat large volumes of water, known systems of this type are connected to large power supplies and 35 used to process large volumes of water, typically many cubic metres per day. The process 3 Summary of the invention In a first aspect, the present invention provides a portable water treatment apparatus for treating polluted water by electrocoagulation, the portable water treatment apparatus comprising: 5 at least two electrodes; and a housing, electrically isolating said at least two electrodes, to which said at least two electrodes are fixed spaced apart from one another, wherein when said at least two electrodes are at least partly submerged in polluted water and provided with an electrical potential, at least one of said at least two 10 electrodes is sacrificial so as to provide ions to the polluted water; wherein said housing is a handle formed of electrical insulating material, said handle being configured for manual gripping, said electrodes being affixed to said handle and at least two of said electrodes being connected to a power supply connection at an end of said handle to provide said electrical potential when in electrical communication with a power supply. 15 In a second aspect, the present invention provides a portable water treatment apparatus for treating polluted water, the apparatus comprising: at least two electrodes; at least one of the at least two electrodes includes one or more of either copper or 20 silver; a housing, electrically isolating the at least three electrodes, to which the at least two electrodes are fixed spaced apart from one another; and at least two of said electrodes being connected to a power supply connection at an end, 25 wherein, when the at least two electrodes are at least partly submerged in the polluted water and provided with an electrical potential, at least one of the at least two electrodes is sacrificial so as to provide ions to the polluted water and at least one of the at least two electrodes is composed of an inert material. 30 In a third aspect, the present invention provides a portable water treatment apparatus for treating polluted water by electrocoagulation, the apparatus comprising: at least three electrodes; and a housing, electrically isolating the at least three electrodes, to which the at least three electrodes are fixed spaced apart from one another, 4 wherein, when the at least three electrodes are at least partly submerged in the polluted water and provided with an electrical potential, at least two of the at least three electrodes is sacrificial so as to provide ions to the polluted water and at least one of the at least three electrodes is composed of an inert material. 5 Preferably, said at least two electrodes are formed from any one of metal foil wrapped around a solid former, plates of thin bent metal, and plates of flat metal and cylindrical metal rods, such that at least two of said electrodes have a cross-section of any one of oval, circular, rectangular, annular, and closed shape. 10 Preferably, said at least two electrodes comprising three electrodes arranged substantially parallel, side-by-side and spaced apart with said electrical potential supplied to each of said three electrodes, with the outermost two electrodes having the same polarity and the inner electrode having the opposite polarity. 15 Preferably, said at least two electrodes comprising three electrodes arranged substantially parallel, side-by-side and spaced apart with said electrical potential supplied to the outermost two of said three electrodes. 20 Preferably, said power supply is either direct current or rectified alternating current, and produces a voltage between about two volts to forty volts. Preferably, the portable water treatment apparatus further comprises an on/off control for said power supply. 25 Preferably, at least one of said at least two electrodes is comprised of at least one material selected from the group consisting of aluminum, iron, magnesium, copper, stainless steel, platinum coated titanium, and silver. 30 Preferably, the at least two sacrificial electrodes are composed of any of aluminium, iron, magnesium, copper or silver and the at least one inert material electrode is stainless steel or platinum coated titanium.

5 Preferably, the at least two sacrificial electrodes are composed of any two of aluminium, iron, magnesium, copper or silver and the at least one inert material electrode is stainless steel or platinum coated titanium. 5 Preferably, the at least two electrodes have a combined mass of less that 15 kg. Preferably, the power supply is a direct current or rectified alternating current power supply that can produce a voltage of between one volt and one hundred volts. 10 Preferably, the power supply is a direct current or rectified alternating current power supply that can produce a voltage of between one volt and one hundred volts. Preferably, the portable water treatment apparatus, further comprises an on/off control for the power supply. 15 Preferably, the direct current power supply includes any one or more of: a rechargeable battery; a single use battery; a solar panel; 20 a portable manual powered electrical generator; a wind powered generator; and a mains power DC power supply. Preferably, the portable water treatment apparatus, further comprises an insulted spacer 25 between the distal ends of the at least two electrodes to maintain their spaced apart separation. Preferably, the each of the at least two electrodes have substantially equal surface area and are parallel in their spaced apart separation 30 Preferably, the at least two electrodes are spaced apart by between 2 to 20 mm.

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11 Brief description of the drawings Fig. 1 is schematic side, front and top views of a first embodiment of a water treatment apparatus; Fig. 2 is schematic side, front and top views of a second embodiment of a water 5 treatment apparatus; Fig. 3 is schematic side, front and top views of a third embodiment of a water treatment apparatus; WO 2007/003003 PCT/AU2006/000934 - 12 Fig. 4 is schematic top and side views of a fourth embodiment of a water treatment apparatus; 5 Fig. 5 is schematic top and side views of a fifth embodiment of a water treatment apparatus; Fig. 6 is schematic top and side views of a sixth embodiment of a water treatment apparatus; 10 Fig. 7 is schematic top and side views of a seventh embodiment of a water treatment apparatus; Fig. 8 is schematic top and side views of an eighth embodiment of a water treatment 15 apparatus; Fig. 9 is schematic top and side views of a ninth embodiment of a water treatment apparatus; 20 Fig. 10 is a schematic top view of a tenth embodiment of water treatment apparatus; Fig. 11 is a schematic top view of an eleventh embodiment of water treatment apparatus; Fig. 12 is a schematic top view of a twelfth embodiment of water treatment apparatus; 25 Fig. 13 is a schematic top view of a thirteenth embodiment of water treatment apparatus; Fig. 14 is a schematic perspective view of a fourteenth embodiment of a water treatment apparatus; and 30 Fig. 15 is two perspective views of a fifteenth embodiment of a water treatment apparatus.

WO 2007/003003 PCT/AU2006/000934 - 13 Detailed description of the preferred embodiments Figures 1 through 8 give an indication of several possible embodiments of portable apparatuses for treating water by electrocoagulation. In all cases, the plate electrodes are held at one position in an insulating assembly. Preferably this assembly should be a 5 handle and, for the sake of simplicity, it will be referred to as a handle from now on. Electrical connections are made to some or all of the electrodes. Although all are illustrated with an electrical insulator keeping the ends apart, this is not an essential feature and is not required if the electrodes are sufficiently rigid that they will stay apart by their own rigidity. However, they must all include a mechanism by which the plates to are supported in a single structure that keeps the plates at different potentials separated from each other. The plates must be connected to a direct current power supply, or a slowly varying alternating current power supply. A direct current power supply could consist of any of the following: 15 a) A battery, rechargeable or one time use b) A solar panel c) A portable manual powered electrical generator d) A rectified alternating current power supply e) Any other source that provides a uni polar polarity electrical voltage with current 20 capability. A voltage rectifier can be built into the handle of the device and producing a rectified AC or smoothed DC voltage. A transformer can be built into the handle so that mains AC could be applied to the water wand and produce the same desired effect. In the same 25 manner, a circuit can be provided that produced a voltage that varied at a frequency of less than 20 cycles per second. This would be referred to as varying voltage direct current, as distinct from alternating current, which is available commercially at 50 cycles per second or 60 cycles per second. All of these variations are considered to be applicable to the described embodiments of the invention. 30 Arrangement of the plates or electrodes As far as the geometry and arrangement of the plates is concerned, it is desirable that the plates have near equal areas and be approximately parallel in their separation. This creates uniform electrode wear and requires minimum power. However, if the plates are 35 not regular shaped and approximately uniformly spaced, the apparatus will still work, but WO 2007/003003 PCT/AU2006/000934 -14 such operation will require greater power. Uniform and parallel or approximately parallel plates are thus preferred. However, uneven and/or irregular plates can be used. Figure 1 illustrates a first embodiment of water treatment apparatus having two plates, 1 5 and 2, which are attached to an insulating handle 4. Each plate has an electrical connection, 5 and 6 respectively, attached. The insulating spacer assembly 7 holds the plates apart at the far end. Although shown in Figure 1, it is not necessary if the insulating handle assembly is sufficiently strong to hold the self-supporting plates rigid for the entire length of the plates. It should also be noted that the handle does not 10 necessarily have to be part of the insulating assembly. The handle could be a conductor and could even be one of the plates. However, an insulating assembly must separate the two active plates. These plates do not need to be parallel sided or parallel spaced. Indeed there are advantages in having the plates closer together at the end away from the insulating handle - they wear away at the ends faster, enabling complete use of the plates is to produce the maximum quantity of water before being replaced. It matters only that they remain electrically isolated from each other, apart from the contact with the water. In operation, the plates 1, 2 are placed in water and a DC power supply, as defined above, with a voltage above 1 volt is applied across 5 and 6. For practical purposes, a voltage above 3 V DC is desired to cause the reaction to occur. 20 In the same manner, Figure 2 illustrates a second embodiment of water treating apparatus using three electrodes 11, 12 and 13, which are held by an insulating handle 14 and connected to electrical connections 15 and 16 respectively. Electrical connection is made to 15 and 16. When this assembly is placed in the water, electrical current flows from 11 25 to 13, creating the reactions given above. However, because the intermediate electrode 12 is between the two, the current must flow through 12 when travelling between 11 and 13. This essentially means that the current is "used twice, making the device more efficient as far as electrical current is concerned. The only disadvantage of this is that the DC voltage must be double the voltage required for the two-plate arrangement shown in 30 Figure 1. The inner plate 12 is illustrated as being slightly larger than the two outer plates 11, 13. This is desirable from a practical point of view to prevent electrical current going directly from plate 11 to 13. Figure 3 illustrates a third embodiment of water treating apparatus using three electrodes 35 embodiment, each of which has an electrical connection. It has two modes of operation.

WO 2007/003003 PCT/AU2006/000934 - 15 In one mode of operation, one polarity voltage is applied to the inner plate 22, via the electrical connection 28. The other two plates, 21 and 23 are electrically connected to the opposite polarity via the electrical connections 25 and 26. In this manner, operation is more suited for a low voltage high current power supply. In practice it would be best 5 suited for a voltage supply in the range 3 V to 6 V, with a suitable current capability. In a second mode of operation, the opposing electrical connections are only made to the outer electrodes, 21 and 23, via the electrical connections 25 and 26. The inner electrode is left floating. This creates the same situation as illustrated in Figure 2. This situation provides maximum efficiency for those power supplies with higher voltage and lower current 10 capabilities. Selection between these two can be done by any convenient method, such as: a) Hard wire selection depending upon the power supply and electrical conductivity of the water. is b) Mechanical switching between the two, either as deemed fit or depending upon the power supply and electrical conductivity of the water. c) Automatically by means of an electrical circuit that could sense the parameters of the power supply and adjust the situation automatically. 20 Figure 4 illustrates a fourth embodiment of water treating apparatus in which five electrodes, 31, 32, 33, 39 and 40 are attached to an insulated handle 34. Only the two external electrodes, 31 and 40 are connected to the DC power source through the leads 35 and 36 respectively. In operation, the electrical current flows between 31 and 40, but because of the intervening plates 32, 33 and 39, the electrical current flows through each 25 of these plates, essentially meaning that the same current is used several times. All the other features such as an electrically insulating assembly or handle to separate the plates are still applicable. Although only examples of two, three and five plates connected in this manner, any 30 number of plates can be employed. The more plates employed, the greater the voltage required, the limit being the voltage above which it is possible to experience an electrical shock and the tendency of the electric current to bypass some of the intermediate electrodes, reducing the efficiency of the process.

WO 2007/003003 PCT/AU2006/000934 -16 Figure 5 illustrates a fifth embodiment of water treating apparatus in which five electrodes, 51, 52, 53, 59 and 60 are attached to an insulated handle 54. The outer electrodes, 51 and 60 are each connected to one polarity of the DC power source through the leads 55 and 56 respectively, while the inner electrode, 53 is connected to the opposite 5 polarity through the lead 58. This situation favours that given in Figure 4 for situations where the power source has a lower voltage and higher current capability. Alternate electrodes can equally be connected alternatively positive and negative. This would effectively increase the surface area of the electrodes, favouring situations where the electrical conductivity of the water is low or the capabilities of the DC power supply are 10 more in keeping with a high current at relatively low voltage. There is no limit to the number of electrodes that can be connected in parallel. This effectively increases the surface area of the electrodes for each polarity. is The water treatment apparatus can be configured in many different ways. For example, the embodiments shown in either of Figures 6 through to 8, in which the electrodes are composed of tubes of material, show one such array. The central rod 81 can also be a tube without affecting the principle of operation. It is connected to one polarity through connection 86, while the outer electrode 82 is connected to the other polarity through 20 connection 87. The whole assembly is supported by insulating handle 75 which also contains insulting spacers 74 to keep the electrodes physically separate. When such an arrangement is placed in the water and operated, it is obvious that the pollutant will rise to the surface because of the production of gas bubbles through the reaction given in equation 3. As such it is desirable, but not essential, that the top of these closed path 25 electrodes have an opening, 79, through which the water can move. Although this opening is shown as a hole, it could equally be a slit, as indicated with the reference numeral 100 of Figure 8. Figures 7 and 8 illustrate embodiments using three cylinders of material. As shown in 30 Figure 7, only the inner, 81, and outer, 83, electrodes are connected to the power supply, through connections 85 and 87 respectively. The middle electrode, 82, becomes a neutral electrode, forcing the current to pass through it, doubling the effect of the passage of electric current. The whole assembly is still held together by an insulating assembly, 84 and 85, that keeps the electrodes electrically insulated from each other. Again the holes 35 in these closed loop electrodes may be desirable in some circumstances, but are not an WO 2007/003003 PCT/AU2006/000934 -17 essential part of the invention. Figure 8 illustrates an embodiment in which there is electrical connection to all three electrodes, 91, 92 and 93. In this case, the inner electrode, 92, is connected to one polarity through 98, while the other two electrodes have a common connection to the opposite polarity through connections 96 and 97 being joined 5 together. The assembly is still held together by an insulating assembly and handle, 94 and 95, with a slot providing a mechanism by which water can recirculate through the assembly. Again the slot may be an advantage in some circumstances, particularly if the whole apparatus is not inserted in the water. This slot can be equally applied to the embodiments described in Figures 6 and 7. The number of these circular or cylindrical 10 electrodes can exceed the three indicated here, with a maximum set at 10 electrodes, it being considered too expensive to manufacture systems containing more than 10 electrodes. The electrodes do not need to be plate-like in appearance, they could equally be rods, as 15 shown in Figure 9. Two only rod electrodes, 101 and 102, are held apart by an insulating handle 104, with electrical connections 105 and 106. One polarity of the power supply is applied to one of the electrodes, with the other polarity being applied to the other electrode. The rods can be of cross-section shapes other than a circular rod, even being square, rectangular, cylindrical or combinations thereof. Neither is the number of 20 electrodes limited to two. Figure 10 shows four rod electrodes, 111, 112, 113 and 117 held in place by an insulating assembly 114, with electrical connections 115, 116, 118 and 119 respectively. As an example, connections 115 and 116 would be connected to one of the polarities, while 118 and 119 would be connected to the other power supply polarity. Yet another embodiment is shown in Figure 11, in which four rod-like electrodes, 121, 25 122, 123 and 127 surround an inner electrode 130. The inner electrode, 130, is connected to one polarity via connection 131, while the other outer electrodes 121, 122, 123 and 127, are connected to the other polarity by connections 125, 126, 128 and 129. Additional numbers of rod electrodes can also be used, as for example a "circle" of 30 electrodes of one polarity surrounding an inner electrode of a different polarity. Equally an array of alternative polarity electrodes is also possible. Equally the electrodes do not have to be of the same or even similar geometry. As shown in Figure 12, it is possible for some of the electrodes to be of a different shape from others. Two rod-like electrodes, 141 and 142 are placed on opposite sides of a plate electrode 143. These must be held 35 together in an insulating handle/support mechanism, 144. They can be connected with WO 2007/003003 PCT/AU2006/000934 - 18 141 and 142 having opposite polarities applied through their connections 145 and 146, with the central electrode, 143, not being connected and acting as a neutral between the two active electrodes 141 and 142. Alternatively the electrical connection to 141 and 142 through 145 and 146 can be the same, while the central electrode, 143, is connected via 5 148 to the opposite polarity. In another alternative illustrated in Figure 13, electrodes 151 and 152 are connected to alternative polarities via connections 155 and 156, with electrode 153 being neutral to both of them. It should be noted that joining the two electrodes 151 and 152 to the same polarity and making 153 the opposite polarity becomes the same as the arrangement shown in Figure 1. 10 The handle can be made of an insulating material and the electrodes may be connected by any suitable means. They may be pennanently attached or connected through some quick fit method. Permanent attachment makes the device a use once and throw-away device, while a quick fit method makes the device a continuous use one with replaceable 15 electrodes. The handle can be one that can be grabbed, or it can simply be a set of spacers similar to that shown as 7, 17, 27 or 37 in Figures 1, 2, 3 and 4 respectively. The handle must enable electrical connections to be made to the appropriate electrodes. In a similar manner, it is possible to have the electrodes supported by the container, as 20 illustrated in the embodiment shown in Figure 14. Electrodes 161 and 162 are held in place in the container 163 by a mounting mechanism, 164, with electrical connections 165 and 166, to which opposite polarity voltages are applied. This whole assembly can still be hand carried. The mounting mechanism, 164, may be either permanently affixed and the container, 163, or it may be removable, in which case the assembly without the 25 container becomes the same as that shown in Figure 1. The arrangements shown in Figures 1 through 13 can be used in place of the two-electrode arrangement shown here. If, however, the electrodes are removable from the container, then the apparatus functions in a similar manner to that shown in Figures 1 through 13 and portability is preserved. 30 In a similar manner, it should also be pointed out that a metal container could also be used as one of the electrodes, as illustrated in the embodiment of Figure 15. Item 172 is both the container and one of the electrodes, connected to the power supply by connector 176. The other electrode 171 has a connector 175 and an insulating component, 174, which enables it to be rested in the container 172 without making electrical contact with it.

WO 2007/003003 PCT/AU2006/000934 -19 Portability is again preserved if the electrode 171 is not permanently affixed to the container 172. Other electrode arrangements can also be used. In particular, the embodiments shown in 5 Figures 6, and 7 would also be useful, when the electrical connection from the outer electrode is removed from the assembly and connected to the container. A weight of less than 15 kg is considered easily handled by the "average" adult male. Because these apparatus should essentially be used when stationary, this is the weight of 10 the empty container and electrode set. Once the water is added, the weight may be anything that the container can handle. Many different geometries are possible for the embodiments of water treatment apparatus, with the actual configuration being determined by the voltage and current available from is the power supply and the conductivity of the water. The dimensions of the electrodes can be any convenient dimension that makes them easily able to be handled by an average adult male using one hand. Convenient dimensions can be 100mm wide by 500 mm long by 3 mm thick. However, they could 20 equally be rods 6 mm diameter by 1000 mm long, or 20 mm diameter by 100 mm long. The dimensions are not the important feature. It is the use of sacrificial electrodes that generate coagulating chemical ions and gas bubbles that are important. The electrodes can have any convenient spacing. However, dimensions smaller than 1 25 mm apart are not considered because the spacing is too small for the coagulated pollution particles to escape from the space between the electrodes. In a similar manner, electrodes with a spacing greater than 200 mm are not considered to be suitable because the power required to drive the electric current between the two electrodes is considered too great for the process to be efficient. An electrode spacing of between 5 mm and 20 mm is 30 considered the most efficient range. Additionally, electrode spacings of between 2 mm and 10 in also impart certain advantages. These distances allow the space between the electrodes to be cleaned, while at the same time are not so great that considerable efficiency is lost by driving the electric current - carried by the ions - through the water.

WO 2007/003003 PCT/AU2006/000934 - 20 Composition of the plates or electrodes This embodiments of water treatment apparatus described above operate on the principle of some of the electrodes being sacrificed by the passage of an electric current through the metal/water surface, liberating active metal ions. The reactions given in equations 1 and 5 2 occur at the anode electrodes. As such the anodes - the positive polarity electrodes must be composed of a sacrificial metal that will give up the appropriate ions. The preferred anode metal is aluminium (Al), but can equally be iron (Fe), both of which are trivalent metals. Another suitable metals is magnesium (Mg), which can assist in the removal of some types of particles from polluted water. In another variation, the anode 10 can be composed of copper (Cu), which is a powerful algicide and can assist in the removal of algae from polluted water. Additionally the use of a silver anode provides ions that kill many pathogens and thus disinfect the water. The cathodes can consist of the same metal as the anode, one of those metals or any other 15 inert metal, such as stainless steel. One of the best cathode materials is platinum coated titanium, it being an inert metal that will not give any contamination to the water. It should be noted that if aluminium is used as the cathode, the reaction: Al+ 4 H 2 0 + e~ gives Al(OH) 4 + 2H 2 (4 20 Or something similar to it can occur at the cathode. This has the advantage that it assists in liberating more aluminium into the water, cleaning it faster and with less electricity usage. The reactions in equations 3 and 4 are competing cathode reactions, meaning that reaction 4 is not the total reaction occurring at the aluminium cathode. 25 Any neutral electrodes will, by necessity, have one side acting as a cathode and the other as an anode. As such, the neutral may likewise be composed of the same material as the anode, e.g., aluminium, iron, magnesium or copper. Or it may be composed of two metals, the cathode acting side of which is made of an inert material such as stainless steel 30 or platinum coated titanium (or equivalent inert material). The other side is composed of an anode metal, (Al, Fe, Mg, Cu). In this case, the two different metals must be electrically combined. When aluminium is used as the cathode material, an oxygen rich insulating layer builds 35 up on the active surface of the cathode. If not removed, this layer ultimately prevents the passage of an electric current through the cathode, stopping the reaction from occurring.

WO 2007/003003 PCT/AU2006/000934 -21 When this occurs, this "oxide" layer of material must be removed by some physical or chemical process. Scraping the surface with a hard sharp object is usually sufficient to ensure the appropriate removal of the material. The presence of materials with extreme zeta potentials and other sources of residual 5 electric charge can also result in the accumulation of materials on the surface of the electrodes. Again this can be sufficient to prevent the passage of the electric current when the electrodes are in the water with a voltage applied. Again, when this occurs, it will be necessary to remove the built up material by scraping them with a hard sharp surface. 10 The number of electrodes required is determined by a combination of the following: 1) The available power supply. With less than 6 volts, it is preferred that all electrodes be connected alternatively positive and negative. However, this does not 15 preclude the use of higher voltages for alternatively connected electrodes - it merely diminishes the efficiency of the process. 2) Above 6 volts, it can be more efficient to use a single neutral electrode between the anode and cathode electrodes. 3) Above 12 volts it can be more efficient to use two neutral electrodes between the 20 anode and cathode electrodes. 4) Above 15 volts, it can be more efficient to use three neutral electrodes between the anode and cathode electrodes. This can be extended to higher voltages and more neutral electrodes, but it generally 25 means that the power supply may not be conveniently available. The use of more electrodes under the situations not described, but otherwise fitting into this pattern, does not prevent the inclusion of this technology. In the same manner, the size and shape of the plates is variable. Long rectangular plates 30 connected at one end are easier to manufacture. Short square or squat plates will fit more easily into a shallow bucket, giving a larger surface area and therefore a faster cleaning than the slender plates illustrated in figures 1 through 4. Non-rectangular plates are more difficult to manufacture, but can have advantages in the ease of fabrication and or replacement. Closed loop electrodes, as illustrated in figures 7 and 8, can have 35 advantages in higher conductivity water because it makes it more difficult for the electric WO 2007/003003 PCT/AU2006/000934 - 22 current to flow through the water from one electrode to the other, bypassing the neutral electrode. In a similar manner, external connections to the plates can be used, which connections 5 can be added or removed as required depending upon the battery being used. Accordingly, the use of plates electrically connected to a DC power supply for the purpose of generating coagulating cations and gas bubbles will aid in cleaning small quantities of polluted water. These plates can be curved or bent. The plates need to be open in order that the gas bubbles can escape from the vicinity of where they are 10 generated and do allow the captured coagulant to float to the surface. The sides of the plates are open. This allows the floated floc to escape from the vicinity of the electrodes and form at the surface. The process works by coagulating the pollutant particles, which then enables their much easier removal. While there is a possibility of is "electrolysis" of pathogens within the water, there is no guarantee that this process would either remove or kill them. In order to be sure the water is suitable for drinking, it is desirable to kill all residual pathogens. There are several methods by which this can be achieved, including the traditional chlorine or bromine disinfection, or other chemical methods. They have the disadvantage of requiring additional supplies. Other methods of 20 ensuring the killing of all pathogens is to add metals that are deleterious to micro organisms. Two such metals are copper and silver. Small quantities of either added to the water will react with bacteria and viruses and render them harmless. These can be added by ensuring that at least one of the anodes either contains one of these metals, or that one of them is in electrical contact with one or more of the anodes, or that an 25 additional anode containing either of these metals is employed. In this manner small quantities of silver or copper are added to the water during the electrocoagulation process. Part of these small amounts may be removed during the settling process. It is important that the amount of disinfectant metal, silver or copper, ions added is in 30 proportion with the amount of coagulant metal added. This is controlled by the relative surface areas of the coagulant metal and the disinfectant metal, the valence of the ions and their atomic weights. Silver is monovalent with an atomic weight of 108, while aluminium is trivalent with an atomic weight of 27. As an example, if it is desired to add 0.5 mg/L silver and 10 mg/L aluminium, it requires an aluminium surface area 20 x 3/4 = 35 15 times that of silver. 20 comes from the ratio 10/0.5 and 3 comes from the requirement WO 2007/003003 PCT/AU2006/000934 - 23 of 3 times as many electrons to release an aluminium ion compared to a silver. The 4 comes from the relative atomic weight differences between aluminium and silver. This calculation assumes that the aluminium and silver are equally spaced from the cathode. It is apparent to those skilled in the art that the use of alloys of these metals, for example 5 brass being an alloy of copper and zinc, still allows the action of the main metal to occur. Operation The use of the embodiments of water treatment apparatuses described shall now be described. Firstly, the water to be cleaned is placed in a container. This container can be 10 of any reasonable size and geometry and can be made of any suitable material such as plastic (clear, translucent or opaque, steel, copper or otherwise as suitable. If a metal container is used, the electrode array must be such that resting the electrodes on the metal container will not cause them to become electrically connected to each other through the metal container. The container must also have an opening at the top that is large enough is for the electrodes of the apparatus to be inserted. It may or may not have a drain tap at the bottom for draining out the cleaned water. If the water container is made of clear plastic it will be easier to determine when the water is clean and the reaction is complete. The size of the container is not critical, but its depth should be of the same order of magnitude as the length of the electrodes and its surface area should be not much larger 20 than twenty times the "swept" area of the electrodes. For this purpose, the swept area of the electrodes is the diameter of a circle that will fully enclose the electrodes. The figure of 20 times the swept area is only a guide for practical purposes - the system will still work even if the swept area is much larger. "Swept" areas as large as 50 times, or even 100 times will still undergo considerable cleaning action. Larger volumes and larger 25 swept areas simply mean that it will take much longer to clean the water and ultimately, if the water volume is too large, it may not be possible to clean it. The container need not be a formal one, and any container which held water could also be used. These could include a plastic sheet appropriately draped in a manner that enabled a 30 volume of water to be retained, which volume had sufficient depth so as to enable the electrodes to be inserted. Ultimately, even a puddle of water retained in a clay surface could be treated in this manner and the treated water appropriately removed for use. Referring initially to Figure 1, the electrodes are placed in a container of water, which 35 causes a current to flow between the electrodes 1 and 2. At the anode, the reaction given WO 2007/003003 PCT/AU2006/000934 - 24 in equations I or 2 (or the equivalent for other metals) will occur, liberating coagulating metal ions, while at the cathode, gas will be liberated. Referring to Figure 2, and other situations in which there is one or more intermediate neutral electrodes, the surface closest to the anode will act like a cathode, while the surface closest to the cathode will 5 act like an anode. The surface acting as the anode will give rise to metal ions according to either of reactions 1 or 2 and the other surface acting as the cathode and liberate gas. The metal ions will coagulate (i.e. bind) with the pollutants, making them larger. They will also result in the coagulated pollutants binding with the liberated gas bubbles. This 10 will cause much of the pollutant to rise up in the water and reach the surface where they will often form a stable structure on the surface. Because of this feature of the bubbles flowing up the electrodes, the water in the vicinity of the bubbles will flow upwards with the bubbles. For this reason, it is desirable that the apparatus has openings at the top that allow the treated water to pass away from the electrodes. This is a natural feature of the 15 plate and rod electrodes, but not necessarily of the closed loop electrode designs shown in Figures 6 through 8. The existence of such an orifice that allows the water to flow out is not necessary if the whole of the electrodes in the wand are placed under the surface of the water. If the apparatus does not have this opening, the process may still work, but with reduced efficiency. As such, these openings, orifices or slots are desirable. 20 It should be pointed out that a sufficient voltage must be maintained between the anode and cathode for there to be enough energy for the reactions given in equations 1 through 4 to occur. In general this requires a DC voltage of at least three volts per anode-cathode set. For practical purposes, it is desired to be greater than 4 volts. However, it is possible 25 for some reaction to occur at a voltage as low as 2 volts per anode-cathode set. As such, the minimum anode - cathode voltage, per set of anode-cathode in series, which forms part of this invention, is set at 2 volts. It should also be noted that this voltage is peak to peak and not root mean square, as far as rectified AC power supplies are concerned. Voltages below 1 volt are considered too low to be of practical use. 30 Most power supplies have a voltage and current limitation. Once a voltage has been applied to the electrodes, the resistance between the water and electrodes detennines the current that will flow between them. If the conductivity of the water is too high for the surface of the electrodes, the voltage output of the power supply may drop so that the 35 minimum voltage is no longer maintained. At this stage, even though the reaction at the WO 2007/003003 PCT/AU2006/000934 -25 cathode will generate gas bubbles, the reaction at the anode will not be sufficient to liberate metal ions and the process will not work. For a given power supply and water conductivity, this can be overcome by putting less area of the electrodes into the water until such time as the voltage increases and the reaction occurs again. 5 There are three mechanisms for determining how much of the electrodes should be inserted into the water. In a first mechanism, the conductivity range of the water to be treated is determined, along with the characteristics of the battery or power supply (characteristics includes voltage and internal resistance characteristics) and the area of the 10 electrodes is calculated to maintain the appropriate voltage and thus have the process work. In a second mechanism, the process is observed to see if a layer of material starts to form over the surface of the electrodes within a few minutes. If no such layer starts to form, 15 the electrodes should be withdrawn a little more and again observed. The process is repeated every few minutes until either the electrodes are withdrawn from the water or a layer of material is observed to start to form on the surface. This is clearly a time consuming and unsatisfactory way of doing it. 20 In the third mechanism the voltage between the anode and cathode is monitored. One method of achieving this is to connect a volt-meter across the anode and cathode and monitor the voltage. If the voltage drops too low, the electrodes are withdrawn until the voltage is above the minimum required voltage. Another method of achieving the same result is to provide a voltage monitoring circuit across the anode and cathode. When the 25 voltage is above the minimum voltage, the voltage monitoring circuit illuminates a light emitting diode (LED) (or other suitable indicator such as a lamp, a signal in a liquid crystal display, suitable mechanical device or any other method of indicating then voltage is satisfactory). When the voltage drops below the minimum required, a different signal is given. This may be the LED is extinguished, or changes colour (or any other suitable 30 electro-mechanical-audio-visual signal to indicate a failure). At this stage, the electrode set that constitutes part of this invention is withdrawn until the electronic, mechanical, audio or visual signal indicates that the voltage is adequate and that the process is operating efficiently.

WO 2007/003003 PCT/AU2006/000934 - 26 The ability to monitor the voltage is a desirable feature. However, if the area of the electrodes is chosen to adequately match the capabilities of the power supply and the conductivity of the water, the design will ensure that the voltage will always be above the minimum required voltage. As indicated above, even if the voltage should fall below the 5 minimum desired, the user has a mechanism of working that out, even if the process does use a certain amount of the available electrical power. The liberated coagulant metal ions will bind to the pollutant particles in the water through the well-known coagulation reactions, making those particles slightly larger. The 10 released gas will form micro-bubbles that will capture the coagulated pollution assemblies and render them buoyant. These buoyant assemblies will then float to the surface, forming a quasi-stable layer. As the pollutant rises, the water will appear cleaner. The action of the gas rising from the electrodes will cause the water to rise with it. This will make sure that the water throughout the container circulates through the plate electrodes. 15 This has two effects. The first is that there is no need to stir the electrodes through the water as it will all pass through them and thus all be cleaned (provided the size of the container is not so large that such can not occur). The second is that micro-organisms within the water will pass between the plates, where they will be subjected to a strong electric force. While such may not be sufficient to kill all micro-organisms, it will 20 decrease the motility of many of them, considerably reducing the numbers of live bacteria left in the water after it has been removed from the floe. Additionally the use of copper and/or silver anodes in addition to the aluminium and/or iron anodes will put Cu and/or Ag ions into the water. Although some of these ions will 25 be removed by the coagulating metals, some will remain to immobilize the residual pathogens given the few hours standing necessary to allow the floe to settle out from the water. In this manner, the water is disinfected as well as being cleaned. At a time adjudged suitable by the operator (e.g. when the water appears clean, or when 30 the floe at the surface of the water starts to turn white) the electrodes can be fully withdrawn from the water. Care should be taken not to stir up the water too much, so that the floe on the surface, which contains the floated pollutant, will not be disturbed and sink back into the water. It is advantageous for the water to remain undisturbed to keep the floc at the top of the water. Alternatively, power to the apparatus can be disconnected, 35 either by removing the power supply from the wand, or turning off a switch between the WO 2007/003003 PCT/AU2006/000934 - 27 power supply and wand. It should be pointed out that once the reaction is complete, even if the water is disturbed such that the floc is broken and redistributed into the water, it will remain separate from the water and will slowly sink to the bottom. Even though the reaction has stopped, there will still be some bubbles in the body of the 5 water. It is thus desirable to wait a few minutes after the apparatus is withdrawn, for all the bubbles to rise up, giving maximum cleaning to the water. This time period could be something like 5 to 30 minutes, depending upon the size of the container. There are advantages to allowing the water to stand for several hours after the reaction has stopped. The smallest bubbles will have risen out of the water and any coagulated pollutants will 10 have much longer to settle to the bottom of the container. Any un-reacted aluminium will settle out onto pollutants or particles. The longer the water stands, for time periods up to several hours, the clearer looking will be the treated water. At some convenient time period after the floe has risen to the surface, it can be removed. 15 This can be done by such techniques as squeezing the container, thus raising the level of the water and causing the floe to flow over the top, or removing the floe by scooping it off the surface, or any other suitable technique. This action leaves less pollutant in the water to settle out. If this floe removal process disturbs the floe, the water can be agitated to break up all the remaining bubbles and the floe will sink to the bottom after a few hours, 20 leaving crystal clear water. This water can simply be poured off to give clear disinfected water suitable for human consumption from many otherwise unsuitable sources. At a further time judged to be suitable, the cleaned water can be withdrawn from the container. If the floe has not been removed, it is desirable when this is done that the floe 25 on the surface is not disturbed when the water is withdrawn. There are several methods of doing this. One is to use a container that has a tap close to the bottom. At that appropriate time, the tap is turned on and the water is drained out. If such a container is not available, the water can simply be siphoned out using a small hose. One end of the hose is placed in the bucket, a vacuum created at the other end and the water withdrawn. 30 It is important that this is done in a controlled manner so as not to disturb the floc. Care needs to be exercised when doing this task to make sure that the floe is not disturbed and the pollutant moved back into the water. A third method is to use a bucket with a pouring spout and simply pour the water out. A fourth method is to use a bucket with a pouring "lip". Simply push the floe away from the lip and pour out the majority of the contents of WO 2007/003003 PCT/AU2006/000934 - 28 the bucket. Please note that in these cases, it is desirable to keep looking at the water being poured out so that the removed pollutant does not contaminate the water again. Another alternative can include stirring the treated water, causing the floating floc to 5 break up and all the particles to settle to the bottom of the container. This leaves the water at the top free of all pollutants and it can simply be poured off or otherwise removed. Another alternative is to pour the water through an appropriate filter. In some cases this can simply be a coarse filter, which did not remove the particles before the electrocoagulation process. If this latter process is used, it is best to allow the water to 10 stand for several hours, anything up to 24 is considered advantageous, before passing the water through the filter. As a general rule, the longer the water is allowed to stand after the apparatus has been turned off or withdrawn, the less treatment that is required to clean a given volume of 15 water. Results When used in the appropriate manner, this technique is capable of removing some 95% to 99.9%+ of many pollutants in the water in one simple action. The amount removed 20 depends upon the nature of the pollutant. It should be noted that the system is only considered suitable for lightly polluted water, that is, water contaminated by mud and septic/sewage overflow and possibly some light industrial or mining pollution. It is not considered suitable for treating septic or sewer wastewater or heavily industrially polluted water. However, if the water treatment apparatus is used in accordance with instructions, 25 the pollutant removal rates are typically as follows: Pollutant Percent Removal Total suspended solids - mud, clay 99+ Turbidity 99+ Bacteria* 99+ Parasites* 99+ Mercury, cadmium, arsenates, lead and other heavy inorganic ions 95 - 99+ Large protein molecules 95-99+ Salinity < 10 WO 2007/003003 PCT/AU2006/000934 -29 Colour - larger dye molecules, tannins 95+ Although the removal rate is only approximately 99%, the use of copper/silver means that the residual pathogens are inactive. 5 After treatment, the water will look clear and have most of the pollutants and pathogens removed. It should appear crystal clear and be much more palatable than the original raw water. In most cases the residual active pathogen rate will be nil. However, there is no guarantee that this process will remove/destroy all the pathogens and as such it cannot be considered as a suitable single step process in producing potable water from all 10 reasonable sources. In water sources that are extremely polluted, other sources of disinfection should be considered. Advantages The primary advantage of the portable water treatment apparatuses described above is 15 they are simple equipment that can remove a wide array of pollutants that are also easy to use and reuse over again by people with very little instruction. The portable water treatment apparatuses described above can also be easily manufactured, carried, and operated almost anywhere with very little electric power and 20 by persons with very little technical capability or assistance. Water treated with the portable water treatment apparatuses described above has most of the pollutants removed and is otherwise vastly more suitable for drinking. Other benefits include: 25 1) The amount of power required by the portable water treatment apparatuses described above is very small. Typically, heavily polluted water could have a turbidity of 100 NTU and contain traces of bacteria. The portable water treatment apparatuses described above could use as little as 0.1 amp hour at 3 volts to clean up to 10 litres of 30 water. Higher levels of pollution would require more electricity to clean the water, lower levels would mean that even more water could be cleaned. 2) The very small amount of power required by the portable water treatment apparatuses described above means that a single six volt five amp hour battery could WO 2007/003003 PCT/AU2006/000934 -30 clean over 500 litre of water. A single small commercial nine-volt battery could be used to clean up to fifty litres of water. 3) The portable water treatment apparatuses described above could be used with a solar panel. On a good clear day, a 12 volt 10 watt solar panel could clean up to could 5 power two or three of the apparatuses and clean over 1,000 to 2,000 litre of polluted water per day. This is a more efficient water treatment than any other mechanism currently available. 4) With small power supplies being available, the ability to provide clean drinking water into remote locations would be considerably enhanced using the portable water 10 treatment apparatuses described above. It also enables persons travelling in remote locations to obtain water along the way, instead of having to carry a full supply with them. Equally important, it enables the provision of clean water with the minimum of infrastructure, as for example for aid relief following natural disasters. 15 Although the invention has been described with reference to preferred embodiments, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Claims (19)

1. A portable water treatment apparatus for treating polluted water by electrocoagulation, the portable water treatment apparatus comprising: s at least two electrodes; and a housing, electrically isolating said at least two electrodes, to which said at least two electrodes are fixed spaced apart from one another, wherein when said at least two electrodes are at least partly submerged in polluted water and provided with an electrical potential, at least one of said at least two io electrodes is sacrificial so as to provide ions to the polluted water; wherein said housing is a handle formed of electrical insulating material, said handle being configured for manual gripping, said electrodes being affixed to said handle and at least two of said electrodes being connected to a power supply connection at an end of said handle to provide said electrical potential when in electrical communication with a power supply. 15

2. A portable water treatment apparatus for treating polluted water, the apparatus comprising: at least two electrodes; at least one of the at least two electrodes includes one or more of either copper or 20 silver; a housing, electrically isolating the at least three electrodes, to which the at least two electrodes are fixed spaced apart from one another; and at least two of said electrodes being connected to a power supply connection at an end, 25 wherein, when the at least two electrodes are at least partly submerged in the polluted water and provided with an electrical potential, at least one of the at least two electrodes is sacrificial so as to provide ions to the polluted water and at least one of the at least two electrodes is composed of an inert material. 30

3. A portable water treatment apparatus for treating polluted water by electrocoagulation, the apparatus comprising: at least three electrodes; and a housing, electrically isolating the at least three electrodes, to which the at least three electrodes are fixed spaced apart from one another, 32 wherein, when the at least three electrodes are at least partly submerged in the polluted water and provided with an electrical potential, at least two of the at least three electrodes is sacrificial so as to provide ions to the polluted water and at least one of the at least three electrodes is composed of an inert material. 5

4. The portable water treatment apparatus according to any of claim 1, 2 and 3, wherein said at least two electrodes are formed from any one of metal foil wrapped around a solid former, plates of thin bent metal, and plates of flat metal and cylindrical metal rods, such that at least two of said electrodes have a cross-section of any one of 10 oval, circular, rectangular, annular, and closed shape.

5. The portable water treatment apparatus according to claim 4, wherein said at least two electrodes comprising three electrodes arranged substantially parallel, side-by side and spaced apart with said electrical potential supplied to each of said three is electrodes, with the outermost two electrodes having the same polarity and the inner electrode having the opposite polarity.

6. The portable water treatment apparatus according to claim 4, wherein said at least two electrodes comprising three electrodes arranged substantially parallel, side-by 20 side and spaced apart with said electrical potential supplied to the outermost two of said three electrodes.

7. The portable water treatment apparatus according to claim 4, wherein said power supply is either direct current or rectified alternating current, and produces a voltage 25 between about two volts to forty volts.

8. The portable water treatment apparatus according to claim 4, further comprising an on/off control for said power supply. 30

9. The portable water treatment apparatus according to claim 2, wherein at least one of said at least two electrodes is comprised of at least one material selected from the group consisting of aluminum, iron, magnesium, copper, stainless steel, platinum coated titanium, and silver. 33

10. The portable water treatment apparatus as claimed in 3, wherein the at least two sacrificial electrodes are composed of any of aluminium, iron, magnesium, copper or silver and the at least one inert material electrode is stainless steel or platinum coated titanium. 5

11. The portable water treatment apparatus as claimed in 3, wherein the at least two sacrificial electrodes are composed of any two of aluminium, iron, magnesium, copper or silver and the at least one inert material electrode is stainless steel or platinum coated titanium. 10

12. The portable water treatment apparatus as claimed in any of the preceding claims, wherein the at least two electrodes have a combined mass of less that 15 kg.

13. The portable water treatment apparatus as claimed in any one of the preceding is claims, in which the power supply is a direct current or rectified alternating current power supply that can produce a voltage of between one volt and one hundred volts.

14. The portable water treatment apparatus as claimed in any one of the preceding claims, in which the power supply is a direct current or rectified alternating current power 20 supply that can produce a voltage of between one volt and one hundred volts.

15. The portable water treatment apparatus as claimed in claim 12, further comprising an on/off control for the power supply. 25

16. The portable water treatment apparatus as claimed in claim 12, wherein the direct current power supply includes any one or more of: a rechargeable battery; a single use battery; a solar panel; 30 a portable manual powered electrical generator; a wind powered generator; and a mains power DC power supply. 34

17. The portable water treatment apparatus as claimed in any one of the preceding claims, further comprising an insulted spacer between the distal ends of the at least two electrodes to maintain their spaced apart separation. 5

18. The portable water treatment apparatus as claimed in any one of the preceding claims, wherein each of the at least two electrodes have substantially equal surface area and are parallel in their spaced apart separation

19. The portable water treatment apparatus as claimed in claim 18, wherein the at 1o least two electrodes are spaced apart by between 2 to 20 mm. Dated 12 July, 2011 Research Water Pty Ltd Patent Attorneys for the Applicant/Nominated Person SPRUSON & FERGUSON