United States Patent
`
`1191
`
`[11] Patent Number:
`
`5,049,252
`
`Murrell
`
`[45] Date of Patent:
`
`Sep. 17, 1991
`
`[54] WATER CLEANING SYSTEM
`
`[76]
`
`Inventor: Wilfred A. Murrell, Wilga Farm,
`Hillston, New South Wales,
`Australia, 2675
`
`[21] App1.No.:
`[22] Filed:
`
`497,850
`
`Mar. 23, 1990
`
`Related US. Application Data
`
`3,925,203 12/1975 Turner ................................ 204/149
`3,944,478
`3/1976 Kuji et a1.
`........................ 204/275
`3,975,269
`8/1976 Ramirez .....
`204/149
`
`4,012,319
`3/1977 Ramirez .....
`204/149
`4,075,076
`2/1978 Xylander ............................. 204/149
`2/1930 Laferty 6161..
`4,189,381
`4,197,180
`4/1980 Woodward ......................... 204/275
`4,202,767
`5/1980 Alfenaar.
`4,294,697 10/1981 Sawa et a1.
`4,311,595
`1/1982 Julke.
`4,623,436 11/1986 Umehara ............................. 204/149
`
`.
`
`[63]
`
`Continuation-impart of Ser. No. 5,726, Jan. 21, 1987,
`abandoned.
`
`FOREIGN PATENT DOCUMENTS
`
`Foreign Application Priority Data
`[30]
`Jan. 21, 1986 [AU] Australia .............................. PH4293
`
`Int. Cl.5 ................................................ C02F 1/46
`[51]
`[52] US. Cl. .................................... 204/268; 204/269;
`204/275; 210/192; 210/243
`[58] Field of Search ............... 210/192, 243, 748, 717;
`204/149, 268, 269, 275, 280, 284, 292
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`.
`
`1/1968 Hougen ............................... 204/149
`Re. 26,329
`3,404,088 10/1968 Dujardin .
`3,479,281 11/1969 Kikindai et al.
`3,562,137
`2/1971 Gehring .
`3,619,391 11/1971 Eisner ................................. 204/149
`3,783,114
`1/1974 Ishii et a1.
`........................... 204/149
`3,816,274
`6/1974 Anderson ............................ 204/149
`3,816,275
`6/1974 lchiki et a1.
`204/149
`
`3,817,865
`6/1974 Austin ...............
`204/149
`3,853,736 12/1974 Harnden et a1.
`1.
`204/269
`
`3,898,150 7/1975 Russell et a1.
`.....
`204/275
`9/1975 Stopka .....
`3,904,521
`210/192
`
`3,920,530 11/1975 Xylander ............................. 204/149
`
`255770 12/1960 Australia .
`5625180
`7/1980 Australia.
`0100538
`2/1984
`European Pat. Off.
`0128782 12/1984
`European Pat. Off.
`0187720 7/1986
`European Pat. Off.
`
`.
`.
`.
`
`Primary Examiner—Peter Hruskoci
`Assistant Examiner—Robert James Popovics
`Attorney, Agent, or Firm—Cushman, Darby & Cushman
`
`[57]
`
`ABSTRACT
`
`A method and apparatus for treating water contained in
`a tank to remove contaminants by passing a current
`through a novel electrode arrangement characterized
`by vertically disposed electrodes plates. Positive and
`negative half length electrode pairs are arranged verti-
`cally with respect to one another. Such electrode pairs
`are used in conjunction with full length, active or pas-
`sive vertical electrode plates which are each adjacent a
`vertical pair. Preferably the electrodes and tank are
`made of aluminium.
`
`10 Claims, 7 Drawing Sheets
`
`700
`
`Tennant Company
`Exhibit 1010
`
`Tennant Company
`Exhibit 1010
`
`

`

`US. Patent
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`sep. 17, 199;
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`She-et 1 of 7
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`US. Patent
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`Sep.l7,1991
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`US. Patent
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`Sep. 17, 1991
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`She-e1 3 of 7
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`Sep 17,1991
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`US. Patent
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`Sep. 17, 1991
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`Sheet 6 of 7
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`5,049,252
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`100
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`US. Patent
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`Sep. 17, 1991’
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`She-et 7 of 7
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`5,049,252
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`

`

`1
`
`WATER CLEANING SYSTEM
`
`5,049,252
`
`2
`and bottom pair. The intermediate electrodes may be
`active or passive.
`g
`This invention in its preferred form does not need the
`addition of chemicals or the use of filtration to provide
`crystal clear clean water. The present invention in its
`preferred form is more efficient and economical than
`other known methods.
`
`Preferably the current is set at a sufficient amperage
`to cause the treatment to be effective in from one to
`three hours.
`
`10
`
`This application is a continuation in part of US. ap-
`plication Ser. No. 07/005,726 filed 01/21/87, now aban-
`doned.
`This invention relates to the treatment of contami-
`nated water for domestic and other uses.
`Many city and town water supplies contain impurities
`and some are turbid. Waters taken from irrigation chan-
`nels, farm dams and directly from rivers are often unsat-
`isfactory for domestic and other uses until treated to
`remove impurities.
`Conventional methods of treatment include filtering
`with or without the addition of chemicals. Used on their
`own, filters are often unsatisfactory, permitting micro-
`fine suspended matter and color to pass through and the
`water remains cloudy. For many years a commonly
`used method of water treatment provides for the addi-
`tion of aluminium sulphate to the water. Trivalent
`AL+++ is very effective at flocculating negatively
`charged suspended particles and hence is useful for
`clearing turbid water. Most contaminants carry small
`negative electrical charges. The combined particles
`then group or cluster together into loose accumulations
`or flocs, which slowly settle to the bottom of the pro-
`cessing tank. After a period of time, the treated water is
`then taken from the tank and filtered, using sand filters,
`to remove the remaining flocculents. More chemicals
`such as soda ash or other alkaline chemicals are then
`added to the processed water to balance out the pH
`changes caused by the addition of alum. Often chlorine
`or other disinfectants are added to reduce algae growth
`and bacteria.
`
`Left behind in the tank is a gelatinous watery sludge
`containing the alum flocculent and contaminants. This
`sludge has to be removed before the next batch of water
`can be treated and the sludge finally disposed of.
`As may readily be seen, this chemical method can be
`both expensive and hazardous to one’s health, while
`requiring frequent maintenance of apparatus and sludge
`disposal.
`Other water treatment apparatus exist in which an
`electric current is passed through the water by way of
`electrodes, however, these devices and methods in the
`past have been complex and costly.
`Furthermore, the use of certain metals such as cop-
`per, silver and iron for the electrodes does work to
`remove some pollutants but further contaminates the
`water with the metal itself.
`It is therefore an object of the present invention to
`provide a method and apparatus for treatment of such
`water, which will overcome or substantially remove the
`disadvantages of the prior art.
`Accordingly, in one broad form, the present inven-
`tion may be said to provide an apparatus and method of
`treating water for the separation and removal of con-
`taminants, said method comprising the steps of: intro-
`ducing a quantity of untreated water into a container;
`passing DC or rectified AC electricity through the
`water by way of vertically arranged aluminium elec-
`trodes so as to treat the water causing at least some of
`the contaminants to rise; removing at least part of the
`water contaminants from the surface of the water; and
`removing at least part of the treated water.
`In another broad form of the invention, the apparatus
`comprises top and bottom electrodes as well as full
`length electrodes between each vertically adjacent top
`
`It is also preferred that the electrodes are produced
`from aluminium.
`The invention, in another broad form, can also be said
`to provide a water treatment apparatus comprising: a
`tank; and a plurality of vertically arranged electrode
`pairs within said tank. Full length electrodes are pro-
`vided between each pair.
`Preferably the apparatus includes means for remov-
`ing contaminated matter floated to the surface during
`treatment of the water within the tank.
`Preferably the voltage and current are adjustable so
`that the current may be set at sufficient amperage to
`carry out the treatment of the water in approximately
`one to three hours.
`The means for removing contaminated matter floated
`to the surface of the water in the tank can be, in one
`preferred form, a weir-like lip at one upper extent of the
`tank, or two similar weir-like lips at opposite ends,
`being slightly below the remaining perimeter of the
`upper sides of the tank, or the tank can be set up with
`one end slightly lower than the other. The floating
`contaminated matter can be swept from the surface of
`the water, over either a lip, or lower end into a recepta-
`cle for disposal.
`Alternatively one means, in another preferred form,
`can be a scoop or skimming device.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`By way of example only, a preferred form of the
`present invention will now be described with reference
`to the accompanying drawings in which:
`FIG. 1 is a schematic representation of a cross sec-
`tional view of an embodiment of the invention in which
`all of the electrodes are connected to a power supply;
`and
`FIG. 2 is another schematic representation, but of
`simpler embodiment, wherein the tank is of metal con-_
`struction and acts as one of the electrodes; and
`FIG. 3 is a schematic representation of a longitudinal
`sectional view of an embodiment of the invention and
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`‘50
`
`‘
`
`55
`
`60
`
`65
`
`illustrating the collection of the contaminants removed
`from the water being treated.
`FIG. 4 is a perspective view of an assembled water
`treatment tank showing nine electrodes.
`FIGS. Sa—Sh depict schematically an arrangement of
`electrodes and possible connection variations attainable
`utilizing the teachings of the present invention.
`FIG. 6 depicts a schematic ofa five element electrode
`according to the present invention.
`FIGS. 7a—7h depict schematically another embodi-
`ment of the present invention.
`FIG. 8 depicts a portion of the electrode of FIG. 7a.
`FIG. 9 depicts, in perspective view, a water purifier
`according to the teachings of the present invention.
`FIG. 10 depicts, in cross section, the attachment of
`electrode plates to one another as taught by the present
`invention.
`
`

`

`5,049,252
`
`«‘3
`Impure water is a conductor of electricity. In this '
`invention, water is purified by a process of passing an
`electrical direct current or rectified alternating current
`through the water, polarizing some impurities and at the
`same time producing extremely small gas bubbles.
`The small gas bubbles generated in this process
`quickly disperse throughout the water in the tank and
`act in a manner similar to positively charged particles,
`attracting the negatively charged contaminant particles,
`causing them to clump or group together, forming a
`floc. Although much contamination is heavier than
`water, in this process, most of the formation will readily
`float to the surface because of the gas content, with only
`a small proportion of the floc remaining in suspension
`after the electric current is removed, when it will either
`slowly float to the surface or settle to the bottom of the
`treatment tank.
`FIG. 1 shows a water treatment apparatus 30 com-
`prising a tank 1 in which are assembled a number of
`electrodes 2. The electrodes 2 are adapted to be alterna-
`tively positive and negative and are provided with re-
`spective interconnections 3 for connection to a suitable
`power supply (not shown). The electrodes 2 are posi-
`tioned within the tank 1 and insulated from the tank and
`
`10
`
`15
`
`20
`
`25
`
`4i
`that the outer electrode plate 40 is connected to one
`polarity and the other outer electrode plate 48 is con-
`nected to the other polarity, with the remaining plates
`insulated and not connected to either polarity. In this
`configuration, because of the conductivity ofthe water,
`the intermediate insulated plates will each take up a
`voltage proportionate between the potential difference
`of the two outer plates and therefore all plates become
`activated. This method allows for the use of higher
`voltages and lower currents for a given amount of
`work, having a considerable advantage in larger instal.
`lations.
`
`The number, size and spacing of electrode plates may
`be varied in order to obtain the most convenient or most
`efficient operational conditions.
`In operation water to be treated enters through the
`valve 5 and the tank 1 is filled to the maximum level 113.
`The electrodes are then connected or switched on to a
`DC or rectified AC power supply.
`The power supply is typically capable of delivering a
`voltage in the region of say 4 to 40 volts at a current
`rating depending on the size of the apparatus. Higher
`voltages may be used in larger installations when ade-
`quate safety precautions are observed. For a 12 volt
`power supply and a domestic sized rectangular tank
`approximately 1.2 meters (long)><0.75 meters (wi-
`de)><0.8 meters (high) and five aluminium electrode
`plates each 0.8 meters (long)x0.6 meters (deep) con-
`nected to alternate polarities a typical preferred current
`will be 12 to 15 amps.
`Preferablyvthe power source will supply 12 to 24
`volts direct current or rectified alternating current, with
`a switch in the circuit. However, voltages and currents
`are not critical. For very large installations higher volt-
`ages offer advantages because of lower currents being
`necessary to do comparable work.
`If water of relatively low conductivity is being pro-
`cessed,
`it may be necessary to increase the number of
`plates 2 and reduce spacing between them and/or in-
`crease voltage in order to maintain a satisfactory pro-
`cessing time of from one to three hours. When the tank
`body 1 is made of aluminium it may be connected to the
`positive polarity to further increase current.
`When the tank 1 is made of conducting material and
`the tank body 1 is connected to one pole of the supply,
`any number of electrodes 2 will suffice. With the tank 1
`insulated from the supply, or when a tank 1 is made of
`PVC, plastic, fibreglass or other non-conducting mate-
`rial, it is necessary to provide a minimum of two elec-
`trodes 2 of opposite polarity, but any higher number of
`electrodes can be used.
`More electrodes 2 and/or closer spacing will increase
`the amount of current for a specified voltage, or alterna—
`tively a lower voltage can be used to maintain a speci-
`fied current flow. A desirable voltage range of between
`4 and 24 is employed for a domestic size tank of approxi-
`mately 150 imperial or 180 US gallons or 680 liters.
`capacity. Higher voltages are not recommended in do-
`mestic installations for safety reasons.
`Typically, the power is applied for a period of ap-
`proximately one hour or longer, however, the time is
`not critical. Higher currents permit shorter processing
`times. The minimum satisfactory time taken will depend
`to an extent upon the voltage and current used and the
`initial state of the water.
`
`from one another, using insulating supports 4.
`FIG. 2 shows a simpler embodiment in which the
`tan_k 1 forms one of the electrodes and a second elec-
`trode 2 is positioned in the centre of the tank 1 and
`insulated therefrom. With this embodiment
`the tank
`may be square or rectangular or may be an upright
`cylinder with the electrode 2 being a pipe or similar
`linear electrode.
`'
`In FIG. 3 the tank 1 is supplied with a water inlet 5,
`clean water outlet 6, deposit outlet 8, a weir 7 and a
`spouting 15. The tank 1 may be tilted very slightly so
`that the lowest point is at the deposit outlet 8. The
`locations of the various inlets and outlets 5 to 8 may be
`selected according to convenience, provided the outlet
`6 is approximately 10 cm above the bottom of the tank
`and the outlet 8 is in the bottom of the tank and the inlet
`5 is placed as low as practicable in either end or either
`side of the tank. The purpose of placing the outlet 8 at
`the lowest point is for ease of drainage and occasional
`flushing of the tank 1 when necessary.
`The purpose of placing inlet 5 as low as practicable,
`but in an end or side of the tank 1, is so that the incom-
`ing water will disturb and mix with any remaining sedi—
`ment from the last previous treatment. The purpose of
`placing the outlet 6 at approximately 10 cm above the
`bottom of the tank is so that processed clean water can
`be removed from the tank 1 without disturbing any
`remaining sedimentary deposits on the bottom. The
`weir 7 has a function which will be elaborated on here-
`inbelow but is essentially a low point around the upper
`perimeter of the tank 1 facilitating the removal of float-
`ing debris from the tank 1. The spout 15 is for directing
`the removed material into a receptacle (not shown) for
`disposal.
`In FIG. 4 it can be seen that there are nine electrodes
`2 in all. In this embodiment the electrodes 2 are sus-
`
`pended on an insulated rod 20 which is attached to the
`tank 1 by either a removable or fixed fitting. In this way,
`the electrode assembly can be arranged externally of the
`tank 1 and placed within the tank 1 in an insulated man-
`ner.
`
`30
`
`35
`
`45
`
`50
`
`55
`
`6O
`
`65
`
`In FIG. 4, the nine electrodes 2 may be connected
`with alternate negative and pOSitive polarities. Alterna-
`tively, and preferably, the electrodes 2 are connected so
`
`FIG. 3 shows the process as time progresses with a
`dense material of coagulated contaminant deposits
`forming in a layer 12 on top of the water, which is a
`
`

`

`5
`combination of fine gas bubbles and most of the contam-
`inants including heavy contaminants. This layer 12 is
`formed by the action of extremely small gas bubbles
`attracting the contaminants and forming a floc, then
`floating to the surface because of gas content. A light
`fluffly or woolly looking thin layer 9 will settle to the
`bottom of the tank, but this layer usually occurs after
`the removal of the power source and some of the sus-
`pended floc has had time to settle.
`The floating layer 12 will contain most of the contam-
`inants and can be removed by sweeping it over the
`lower lip 7 into the spouting 15 and disposed of. For a
`domestic size tank the removal can be achieved by the
`use of a batten fitted with a length of rubber insertion
`material of a length equal to the width of the tank 1 and
`sweeping the layer 12 over the lower lip 7 into the
`spouting 15 to a container (not shown) for disposal.
`Alternatively, a scoop may be used for removal of this
`layer 12, in which case the scoop should be made of a
`plastic or insulating material. For typical contaminated
`river water or farm dam water, the amount of removed
`material for disposal is approximately one percent of the
`tank capacity.
`When adequate treatment of the water is completed,
`the power source is switched off and the layer 12 of
`contaminated material
`is swept off or otherwise re-
`moved. The activity within the tank will continue for
`some time after the current is removed, because of the
`charge held in the electrode plates. In a typical opera-
`tion, after one or two hours, the time not being critical,
`a further sweeping of a light layer from the surface of
`the water is advisable but not essential for best results.
`Preferably the treated water 11 within the tank 1 is
`then allowed to settle for several hours or overnight,
`after which the clean processed water 11 can be re-
`moved through the controlled outlet 6.
`Because the controlled outlet 6 is positioned some
`distance above the bottom of the tank, the light layer 9
`of settled material is not disturbed when the processed
`water 11 is removed or pumper out.
`After removal of the processed water 11, a new lot of
`water for
`treatment
`is
`introduced into the tank 1
`through the controlled inlet 5, which will stir up the
`settled light layer 9, mixing it into the incoming water
`and the process is repeated.
`The tank 1 does not need to be cleaned or flushed out
`until after very many cycles, because the residue from
`one treatment cycle is mixed with the incoming water
`and most of it goes out with the sweeping of layer 12 on
`the next cycle.
`If it is desired to clean out the tank 1, it is only neces-
`sary to open the controlled outlet 8 until the remaining
`water is drained away and then hose out the tank and
`electrode plates with preferably clean water.
`It is preferred that all the electrodes 2 are produced
`from sheet aluminium of 1.5 mm or heavier gauge, how-
`ever the electrodes may be in the form of sheets, plates,
`rods, tubes, mesh or net, the number varied and addi-
`tional electrodes made of other materials such as car-
`bon. The surface area of the electrodes 2, spacing, volt-
`age and the conductivity of the water all contribute
`when determining the amount of current in the circuit.
`In fact, with well worn aluminium electrodes, the pit—
`ting on .the surface of the electrode acts so as to effec-
`tively increase the surface area leading to increased
`performance.
`‘
`The tank 1 may be made of conducting material,
`preferably aluminium. Alternatively the tank 1 may be
`
`10
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`20
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`25
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`30
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`35
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`50
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`55
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`5,049,252
`
`6
`made of non-conducting material such as fibreglass,
`PVC or other. Tank 1 shape is unimportant other than
`that a square or rectangular tank is easier for removal of
`the floating contaminants.
`it may be
`When the tank 1 is made of aluminium,
`either connected to the positive polarity or be fully
`insulated from the power source.
`If the tank 1 is connected to the negative polarity, it
`will function normally, but the tank inner surface 'will
`deteriorate over a length period of time. When the tank
`1 is made of conductive material but insulated from the
`
`power source and electrodes, the tank 1 will take up a
`potential somewhere between the negative and positive
`voltages of the electrodes.
`Because of the characteristic of the system described
`in the last preceding paragraph, metallic tanks of some
`materials are unsatisfactory for extended use, for exam-
`ple, galvanised iron, because the galvanising will deteri-
`orate rapidly. Tanks made of plastic materials are pref-
`erable to metal tanks, with the exception of aluminium.
`For a 12 to 14 volt power source the range is pre-
`ferred between half to one milliampere per square centi-
`meter of electrode area of 15 to 40 milliamperes per liter
`of water capacity of the treatment tank. The preferred
`range of milliwatts per liter is 200 to 500 milliwatts.
`Large departures from these parameters will work satis-
`factorily, but with lower energy rates times will be
`extended.
`
`If water of slightly reduced quality is acceptable, then
`processing time can be considerably reduced by increas-
`ing currents and decreasing settlement time.
`The size of treatment tanks can be anywhere from
`very small units suitable for travellers to carry and
`operate from flashlight cells or small portable units for
`campers to operate from automobile batteries, up to the
`largest installations suitable for city water supplies.
`Further preferred electrode arrangements are dis-
`closed with reference to FIGS. 5—8. It should be appre-
`ciated that these electrode arrangements may be used in
`conjunction with a wide variety of tanks and methods
`including those previously disclosed or
`suggested
`herein. The following electrodes offer some or all of the
`following advantages over electrodes known in the
`prior art, while offering at the same time low cost and
`simplicity:
`(a) they provide a wider control over currents in
`order to cope with a variety of raw water conduc-
`tivities by varying connections possibilites to termi-
`nals on the outside of the tank;
`(b) they improve water circulation within the tank
`during treatment;
`(0) they improve efficiency over previous element
`types by producing a smaller microbubble for a
`given current density;
`'
`((1) they provide extended life of the element elec-
`trode plates over previous types;
`(e) they reduce the amount of residual deposits set-
`tling to the bottom of the tank, thereby extending
`the number of cycles between draining and hosing
`out;
`time-consuming
`(0 they enable easier and less
`change-over when removing and replacing an ele-
`ment module; and
`(g) they extend the range of operation for waters of
`higher conductivities, but still using all the surface
`area of the element module plates,
`therefore in—
`creasing. plate life.
`
`

`

`5,049,252
`
`7
`With reference to current control and versatility the
`following should be noted. Early versions of apparatus
`made in accordance with the teachings of the present
`invention utilized power transformers having second-
`ary windings of 16.5 volts. Improved versatility was
`realized with upgraded transformers having primary
`windings with 220, 240 and 260 volt tappings and sec-
`ondary windings with tappings at 9,
`l8 and 26 volts.
`Secondaries preferably have 25 amperes continuous
`rating, providing rectified voltages of approximately 7,
`15 and 23 volts.
`These various voltages may be applied to a versatile
`electrode arrangement 100 as shown in FIGS. 5—8. In
`the electrode arrangement depicted in FIGS. Sa—Sh is
`characterized by a first bank of 5 lower electrodes 101,
`a second bank of 5 lower electrodes 102 (alternating
`with the first lower electrodes 101), a bank of 10 upper
`electrodes 103, and a bank of 11 full length electrodes
`104. The upper and lower electrodes are about half as
`long as the full length electrodes. The upper electrodes
`are each associated with a vertically adjacent lower
`electrode. The full length electrodes alternate with the
`other electrodes. As a result there are four terminals a,
`b, c and d to the electrodes which are preferrably lo-
`cated on the exterior of the purifying tank. Terminal a is
`connected to the full length electrodes which are con-
`nected to one another. Terminal b is connected to the
`first lower bank 101. Terminal c is connected to the
`second‘lower bank 102. Terminal (.1 is connected to the
`upper bank 103. If positive voltage is applied to terminal
`a and negative voltage is applied to terminals b, c and d
`(as shown in FIG. 5a) then the current at a given volt-
`age for the arrangement of FIG. 5a is designated 24x. It
`follows that the current of the terminal arrangement of
`FIG. 5b would'be 18x. The arrangements suggested in
`FIGS. 5c and 5d vield a current of 12x, the Sc arrange-
`ment wearing out the lower electrodes only, and the 5d
`arrangement wearing only the upper electrodes.
`The connection depicted in FIG. Se is considered
`undesirable because of a relatively fast wear on only
`25% of the plates and giving 6x current, whereas the
`connections shown in FIG. 5f also gives 6x current, but
`has all plate surfaces in operation, thus extending elec—
`trode life greatly. This is considered the best electrode
`terminal connection arrangement in the group shown in
`FIGS. 5a—5h. FIG. 5g shows a connection arrangement
`for a 45x current and FIG. 5h provides a current of 3x.
`In practice waters with many different conductivities
`can be processed with a device having the electrodes
`100 connected as shown in FIG. 5f. The FIG. 5a con-
`nection arrangement may be more appropriate for low
`conductivity water.
`_
`Water circulation within the tank is provided by
`action of rising oxygen and hydrogen microbubbles.
`These electrode element modules provide a greater area
`coverage of the bottom of the tank for a given total
`plate surface area and may be located approximately 70
`to 80 mm above the tank bottom in a position which
`causes a symmetrical circular water motion, like a “fig-
`ure 8" on its side, when viewed end on to the element
`module. Gas is produced from every square centimeter
`of active plate surface and all gas originates in approxi-
`mately the lower 30% of water, with 70% of the water
`being above the top of the plates. This provides a gentle
`but thorough circulation of water within the tank every
`few minutes, without any mechanical aid or moving
`parts. Horizontal spacing between element electrode
`plates is around 23 mm which is not critical, but this
`
`8
`spacing does provide easy circulation of water through
`the element.
`
`Efficiency has been greatly improved by the arrange-
`ment of having half of the plates divided into two
`pieces, one above the other, with a vertical gap of ap-
`proximately 20 or more millimeters. It will be noted in
`FIG. Sa that there is one row of half plates on the top
`and one row of half plates on the bottom. For example
`in a 21 plate element module, there are 10 half plates on
`the top connected to terminal d and 10 half plates on the
`bottom with 5 half plates connected to terminal c and
`the other 5 connected to terminal b. The eleven full
`sized plates are interconnected to each other and con-
`nected to terminal a. All connections may be self con-
`tained within the module, with terminals a, b, c and (1
`brought out to inside the power supply box externally
`of the tank. The greatest efficiency is with FIG. 5f,
`where the negative potential is connected to the top
`row of half plates and the positive potential connected
`to all the bottom row of half plates (in essence forming
`a single lower bank of lower electrodes) with no con-
`nections to the full sized plates, which are in series and
`taking up half the value of voltage between the bottom
`and top plates. Polarity reversal will give identical re-
`sults and a double pole double throw switch may be
`built in for this purpose, being reversed every alternate
`batch. This evens up wear and reduces scale build up on
`element plates.
`The precise number of electrodes is not critical. For
`the sake of clarity a five element arrangement is further
`explained with reference to FIG. 6. In this example it
`will be seen that a 12 volt negative potential is applied
`to terminal d which is activating half plates y and w. In
`turn we have the positive of this supply connected to
`terminals c and b which are providing a zero positive
`potential to halfplates r and t. The three full sized plates
`have no power directly connected to them, but as water
`is a conductor and plates equally spaced, then the three
`full sized plates will take up a potential of negative 6
`volts. In other words we have a 12 volt supply, but
`there will only be 6 volts between any two adjacent
`plates. The centre one of these full sized plates xs will be
`described, but others will operate in exactly the same
`manner. The top half of this plate x, being a negative 6
`volts will be 6 volts positive relative to half plates y and
`w which are at negative 12 volts, whereas the bottom
`half of the xs or s which is also at negative 6 volts will
`be negative 6 volts relative to the two lower half plates
`r and t, which are at zero positive potential.
`Under these circumstances, the lower half of the full
`sized plates u, s and q will generate hydrogen microbub-
`bles, whereas the top halves z, x and v will generate
`oxygen microbubbles. Although they are at the same
`voltage of negative 6, because of the voltage dividing
`action of the water resistance, or conductivity, relative
`to their adjacent plates, the top halves will act precisely
`like positive plates and the bottom halves will act pre—
`cisely like negative plates. Therefore these gases will
`rise in the same plane and intermingle, which has the
`effect of reducing the tendency of many small hydrogen
`bubbles from joining together and forming a larger
`hydrogen bubble. Because the half plates are at opposite
`‘ polarities, in this case the top ones being negative and
`the lower ones being positive, the same thing applies.
`Both oxygen and hydrogen microbubbles will rise to-
`. gether above every one of the plates. This provides a
`more rapid and better dispersal of hydrogen bubbles
`throughout the water being processed. Hydrogen bub—
`
`10
`
`_
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`65
`
`

`

`5,049,252
`
`9
`bles, being more prolific and lighter than oxygen bub-
`bles, rise more rapidly and rising from all the plates
`gives a superior circulation rate of the water during
`treatment.
`
`The designs incorporating split plates with intermedi-
`ate plates have a further advantage over previous de-
`signs, inasmuch as a greatly reduced quantity of residue
`settles to the bottom of the tank. Almost all of the con-
`taminants rise to the surface because of the more effi-
`cient production of gas microbubbles.
`A further development
`is an element module as
`shown in FIGS. 7a-7h with preferably 21 or more
`plates based on the principles and terminal connection
`arrangements of the last mentioned type, but being
`designed for higher conductivity water of above 900
`uS/cm. With 21 plates the current range is from 6x to
`0.75x or a ratio of 8:1. However for a direct comparison
`with the last 21 plate element of FIGS. 5a through 5h,
`this element will draw only a quarter the current for a
`given connection, voltage and water. This means that
`for high conductivity water of more than 900 uS/cm,
`this new element has the advantage of being capable of
`using a higher voltage when all the plate surfaces are
`energised.
`This design provides an additional half sized plate 105
`between each activated half plate and th