BACKGROUND OF THE INVENTION The problems of treating water to remove or destroy pathogenic organisms is well known. Examples of lethal water born bacterial organisms include those responsible for cholera, typhoid and dysentery symptomatic diseases caused by bacteria such as enteric type bacteria (for example Escherichia coll). Less lethal but still extremely dangerous organisms include those which cause Legionella, Salmonella, Pneumonia and dysenteric conditions caused by less harmful strains of Escherichia coli. The least harmful strains of water born bacteria that are of concern to humans are those that can cause diarrhoea. Overseas travelers are often advised not to drink the water mainly because of this.

There is a need to treat water so that such bacterial organisms are reduced to a level that they can no longer cause harm to humans or animals. In some cases this requires a bacterial count of less than one part per million per sample. Few systems are saleable which enable treatment for example of a single cup of water to, the water storage system for say the city the size of Hong Kong as well as being able to be used for commercial and industrial applications. Systems for remote areas also present a problem where electricity or other forms of energy required by treatment plants are expensive. Treatment of closed systems such as air-conditioners and commercial industrial systems currently require regular flushing of all the water in the

systems. The transporting of biocides also requires special equipment and the maintenance of such systems often require specialist training.

Ever since 1904 when Sir Alexander Houston demonstrated that the addition of chlorine to water killed the typhoid bacillus, traditional water treatment systems have been chemically based. In such traditional systems, untreated water is taken from a storage area such as a dam and a flocculent is added to the water. The flocculent removes larger particles from the water by forming a colloidal mass which is allowed to settle to form a sediment. The water is then decanted and filtered to remove further particulate matter and suspended colloidal materials. To increase the effectiveness of the purification or disinfection process, the water can then be aerated to introduce greater levels of oxygen so that any chemical reaction is made more effective.

Usually, chlorine is added to the water as a disinfectant. Bacteria are killed by chlorine which is poisonous. A residual chlorine content is however required to maintain the bacterial count of the water at acceptable levels. In the case of commercial and industrial air-conditioning systems hydrogen peroxide is sometimes used to kill the bacteria. More recently, systems have been developed using a process known as reverse osmosis. Reverse osmosis is not an aeration process but is a physical process which forces the water through a fine membrane. A standard reverse osmosis membrane has filters with a pore size in the order of one micron.

Pore sizes however may vary between manufactures. A pore size in the order of one micron is considered to be too small for the passage of most bacteria.

Recent prior art methods of water treatment have also included ultra violet radiation which has been employed in disinfecting water for swimming pools and for

the treatment of military and some municipal water supplies where economic factors are not of primary significance. The ultra violet systems work by killing bacteria using low levels of radiation produced by short ultra violet wavelengths of the light being emitted.

The prior art however has limitations and disadvantages. In the case of traditional chlorine based systems disadvantages include the fact that water does not taste as pleasant when chlorine has been added. In some cases residual chemicals which are hazardous to human health are produced such as trihalomethanes (THM) when chlorine in water bonds with decaying organic matter. THM's are carcinogenic.

The transportation and handling of chemical additives to water supplies requires special permits and special equipment; the use of chemicals also requires protective equipment for workers who must also be provided with special training in appropriate chemical procedures; the storage of such chemicals requires special sites in order to protect from toxic spills which can occur; maintenance of chemical systems is expensive and requires specially trained staff; chlorine resistance strains of bacteria are starting to emerge, and the hydrochloric acid present from the addition of chlorine to water accelerates the deterioration of attached equipment.

The disadvantages associated with the reverse osmosis system include the consumption of large amounts of electrical energy in relation to the drinkable water produced; bacteria which is smaller than the pore size (usually approximately one micron) of the membrane used pass through unaffected; there is no residual biocides to remove any bacteria collected during the distribution of the water; any break in the membrane used in the system means that all the collected matter is dumped back into

the water; there is often a wastage of up to ten times the water produced for example the system may waste 10 litres of untreated water to produce one litre of usable water ; reverse osmosis systems are expensive to purchase and require specialist maintenance.

Disadvantages associated with ultra violet systems (UV) include the fact that the ultra violet irradiation is not effective with water containing particulate matter; UV systems consume large amounts of electrical energy for the usable water produced; there are no residual biocides, any bacteria collected during distributions go directly to the consumer; UV is a high maintenance system; UV tube replacement requires specialist technicians and UV systems are in general costly to produce.

OBJECT OF THE INVENTION It is therefore an object of the present invention to seek to ameliorate some of the disadvantages and limitations of the prior art or to at least provide the public with a useful choice.

STATEMENT OF THE INVENTION According to one aspect, the invention resides in a water treatment apparatus including in combination a water passage means having an inlet and an outlet to allow for the passage of water to and from the water passage means, sacrificial electrode means immersed in the water power supply means to supply electric current to the electrode means, means for sampling the water typically upstream of the electrode means, the sampling means adapted to determine microbial content and dissolved solids in the water, control means adapted to control the power supply, wherein in operation, the control means is used to vary the electric current to the electrode means wherein

charged redox electrode material is released into the water as a biocide relative to the turbidity and the microbial content of the water sampled.

Preferably the control means is a microprocessor control means adapted to receive feedback signal information from the sampling means wherein the microprocessor control means responds by varying the current to the electrodes relative to the turbidity and the microbial content of the water sampled.

In the alternative, the control means can be an analogue system utilising comparators or a digital system without a microprocessor.

Preferably the sampling means determines the microbial content in a sample of water with adjustment for the turbidity of the water.

Preferably the sampling means is a quick response sampling and re sampling means wherein adjustments to the electric current by the microprocessor control means occurs in the order of milliseconds.

In an example where the electrodes are supplied with a constant voltage, the change in conductance, resistance or impedance measured at the electrodes provides an indication of changes to the microbial content of the water.

Preferably the sampling means incorporates an active feedback system which utilises a fully variable output of voltage and current controlled by specially adapted algorithms wherein an input is provided by electrodes in the water to measure the changes to microbial content and/or turbidity.

Additionally there may be a feed forward system associated with the sampling means wherein current is constant and voltage is varied according to the changes in microbial count detected by electrodes acting as a transducer monitoring a change in output.

Preferably the redox ions released into the water exceeds the requisite amount to kill the bacteria by five percent (5%).

Preferably the electrodes can be cleaned by reversing the polarity of the electric current supply to the electrodes over a given period of time.

Preferably the microprocessor control system can control up to four (4) electrodes which can treat water at a flow rate of up to 4,500 litres (or 1000 gallons) of water per hour. Preferably for greater flow rates the system can be configured as a modular system and additions of modules can be controlled by a master control system.

Preferably the apparatus can be operated by a power supply which can include mains power with a suitable converter, a battery, or a DC supply.

The power supply can be a solar cell coupled to a suitable battery for wet weather or night time application.

In the alternative in areas where there is little sunlight but more wind the power supply can be an alternator/generator attached to a suitable windmill and battery for night time application or when there is no wind.

Preferably the sacrificial electrodes comprise a redox element or combination of redox elements as an alloy mixture to suit the disinfection process required including

a) an alloy mixture of eight parts silver and three parts copper by weight, or b) an alloy mixture of eight parts aluminium and three parts silver by weight, or c) an almost pure silver electrode, or d) an alloy mixture of thirty-three parts copper and eight parts zinc, or e) an alloy mixture of ten parts aluminium and three parts zinc.

Preferably the electrodes are produced as plates three (3) to four (4) millimetres thick which are spaced no greater than four (4) millimetres apart on an electrode array so that the flow of water is past the widest part of the plate and the electrodes are wired individually or in pairs to a controlled power input via a jack plug.

In the alternative the electrodes can be a multiple rod array on a single electrode base member comprising rods of silver and copper but may be any redox material.

Preferably the electrodes are installed in a manifold so that the number of electrodes may be changed for each application and flow rate.

Suitably the system is saleable for the treatment of small quantities of water up to flow rates of the order of megalitres of water per hour.

Preferably the electrodes are constructed so as to be installed and removed by means of a single spanner or wrench.

Suitably the electrodes are sealed in the manifold by means of Teflon gas tape wound around a threaded electrode base that screws into the manifold. Alternatively electrodes may be designed to partially float in or on the water as required.

Suitably each electrode is sealed internally by use of potable epoxy resin or equivalent.

SUBSTITUTE SHEET (RULE 26)

Preferably the electrode bases and the manifold are constructed of an inert material such as potable poly vinyl chloride (PVC) plastic.

Suitably the number and construction of electrodes is determined by the required flow rate.

Preferably the treated water is allowed to stand in a sunlit proof container for ninety minutes following treatment by the apparatus to ensure bacteria killed to a safe level is achieved.

Preferably the microprocessor control system is a programmable loop controller (PLC) system capable of monitoring the resistance, impedance, or conductance of the electrodes to enable the adjusting of power output to the electrodes via a connection.

Preferably the microprocessor system is associated with software adapted to drive the microprocessor control system.

Preferably there is a flow and/or pressure detecting means adapted to detect the flow or pressure of water in the tubular vessel to switch the system on or off in the presence or absence of the flow of water in the tubular vessel in the interest of conserving electric power. In a preferred version the flow and/or pressure detecting means can be associated with a timer adapted also to switch the system on and off.

In another aspect the invention resides in a method for treating water including the steps of: + allowing water to flow through a water passage means, + the water passage means containing sacrificed electrode means immersed in the water, + supplying electric power to the electrode means,

+ sampling water by water sampling means adapted to determine microbial content and dissolved solids in the water, + controlling the electric power to the electrodes by microprocessor control means in response to information signals received from the sampling means, the electric power causing the electrodes to release positively charged redox electrode material into the water as a biocide relative to the turbidity and microbial content of the water sampled.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the present invention be more readily understood and put into practical effect, reference will now be made to the accompanying illustrations wherein : Figure 1, Figure 2 and Figure 3 show preferred embodiments of the invention according to Example 1.

DETAILED DESCRIPTION OF THE DRAWINGS Example 1 Referring now to the drawings there is shown in Figure 1, Figure 2 and Figure 3 a preferred embodiment of the invention according to Example 1. In Figure 1 there is shown a preferred water treatment apparatus wherein there is a water passage in the form of a tubular vessel 10 having an inlet 12 and an outlet 14 portion to allow for the passage of water through the vessel. Immersed in the tubular vessel are four electrode members 16,18, 20,22 which are connected to a microprocessor control means 24 by means of electrical wire connections 26. The microprocessor control means receives power from a power transformer 28 as well as from a wind generator device 30 and/or a solar panel 32 which are used to charge a car battery 34 in order to

provide power during night time application or when there is little or no wind. The preferred power input to the microprocessor control means is in the order of 12volts 3 amps direct current which is supplied to the electrode members connected in parallel.

The microprocessor control unit is also shown with a series of alarm indicators 36 in the form of light emitting diodes (LED). The alarm indicators indicate the changes in inductance and/or resistance measured by the electrodes as probes measuring the turbidity and microbial count of the water. In this example, the apparatus is able to treat up to and including a flow of 5000 litres of water per hour. There is also shown a side stream pressure switch 38 which is connected to the microprocessor control unit adapted to detect the inflow of water to switch the system on and off thereby conserving power when there is no water flow. This switch may be a pressure switch, differential pressure switch, flow switch, power switch, relay or other type of switch as required. The switch can also be associated with a timer.

Figure 2 shows detail of the front and side views of the microprocessor control unit as described for Figure 1. The microprocessor control unit 24 has electrical terminals 40,42 preferably sockets adapted for engaging jack plugs connected to the electrical wiring connecting the electrodes.

There is also shown a control screen 44 and a series of alarm light emitting diodes (LED's) 36 to display information concerning the operation of the apparatus and the level of inductance and/or resistance at the electrodes as an indication of turbidity and microbial content. In the side view of the microprocessor control unit there is shown a DC power input socket 46 for connection to the solar panel and/or wind generator and the battery back up power source. There is also shown a switch sensor input 48 for the side stream pressure switch used to detect pressure of water

preferably upstream of the electrodes proximal to the inlet portion of the tubular vessel.

Figure 3 shows detail of the side and front views of one of the electrode members 16 wherein the electrode member is comprised of plates 50,52 preferably four millimetres (4mm) thick and spaced not more than four millimetres (4mm) apart.

The plates are preferably an alloy mixture of silver and copper or in the alternative, an alloy mixture of aluminium and silver or any redox material or redox alloy as required by the application. The electrodes have a threaded portion 16a for screwing into the tubular vessel preferably by means of a single spanner or wrench with the use of Teflon gas tape wound around the threaded portion of the electrode assembly to provide a completely water tight seal with the vessel.

ADVANTAGES The advantages of the present invention include ; + cheaper than a similarly sized chlorine, RO or UV systems to purchase. cheaper to run than other systems + no special transport or handling required for biocides + can be successfully installed in remote locations + electrodes are easily replaced + DCS is automatic in adjustment + Red alarm if there is a system problem + Works with open or closed systems VARIATIONS

It will of course be realised that while the foregoing has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is herein set forth.

Throughout the description and claims this specification the word"comprise" and variations of that word such as"comprises"and"comprising", are not intended to exclude other additives, components, integers or steps.