EP3003993A1

EP3003993A1 - Water treatment apparatus

Info

Publication number: EP3003993A1
Application number: EP14736919.3A
Authority: EP
Inventors: Thomas Murray MACDONALD
Original assignee: Managed Technologies Ltd
Current assignee: Managed Technologies Ltd
Priority date: 2013-06-03
Filing date: 2014-06-03
Publication date: 2016-04-13
Also published as: GB201409846D0; GB2517546A; WO2014195686A1; GB2517546A8; GB201309879D0; GB2517546B

Abstract

Water treatment apparatus comprises a reaction chamber and a source of hydrogen peroxide. The reaction chamber comprises at least one inlet for allowing ingress of water into the reaction chamber and at least one outlet for allowing egress of water from the reaction chamber. The apparatus also includes means for dispensing hydrogen peroxide into the reaction chamber and a lens for heating the water in the reaction chamber.

Description

Water Treatment Apparatus

Field of the Invention

The invention relates to water treatment apparatus, and more particularly to apparatus for treating standing water supplies to reduce total bacteria and micro-organism counts within the water.

Background of the Invention

A safe drinking water supply is vitally important in the rearing of healthy livestock and poultry.

Bacteria, viruses, micro-organisms and parasites are regularly found in water sources. While most micro-organisms in livestock water supplies are quite harmless there are some organisms that can contribute to reduced livestock health and performance. A contaminated water source can spread a pathogen quickly throughout the herd and could ultimately reach humans.

In many cases these organisms pose a greater threat to humans than to the livestock themselves.

There is increasing recognition of the role that drinking water has as a transmission vector for a number of pathogens that pose a threat to both livestock and as a link in an infection transmission chain that could ultimately reach humans. In addition, where livestock water troughs or other drinking vessels are connected to mains water supply there is a risk that mains water supplies can become contaminated with pathogens from the livestock water if the trough or drinking vessel is defective.

A total bacteria count measures virtually all pathogenic as well as non infectious bacteria that use nutrients for growth. A total bacteria count in excess of 500 colony-forming units (CFU) per 100 ml may indicate problems with the water quality. Water sources with total bacteria counts in excess of 1 million CFU per 100 ml should be avoided for all livestock. The desired level of total bacteria count for livestock water is less than 200 CFU/ 100ml.

Coliforms are bacteria that normally inhabit the digestive tracts of humans, livestock and other animals. Some water sources where livestock have free access can reach coliform concentrations exceeding 15,000 counts per millilitre (ml). Maximum levels of coliforms should not exceed 5000 counts per 100ml of water. Fecal coliforms are a subset of total coliform bacteria that are more fecal-specific in origin. Livestock water sources should have less than 1 fecal coliform count per 100ml of water. Problems can occur in young animals when the fecal coliform levels are greater than 1 count per 100ml of water. Problems in older animals can occur with fecal coliform counts of more than 10 per 100ml. Fecal streptococci generally occur in the digestive systems of humans and other animals. Fecal streptococci levels should also be less than 1 count per 100 ml of water and problems can occur in young animals when the fecal streptococci levels are greater than 3 counts per 100ml. Problems in older animals can occur with fecal streptococci counts of more than 30 per 100ml The use of hydrogen peroxide and ozone (perozone) in water disinfection is well known, however this strategy would not be viable for the treatment of livestock water due to the electrical requirements of ozone generators at the site of water troughs and other drinking vessels. In addition, such systems are complex and expensive to install and maintain. Another known method of water decontamination is a process called Solar Disinfection (SODIS). SODIS is a system that uses the UV-A spectrum of sunlight to inactivate pathogens in drinking water. The water to be treated is poured into polyethylene terephthalate (PET) bottles, shaken to increase the dissolved oxygen content, and then left in direct sunlight for a period of at least 6 hours. SODIS was developed over many years for developing countries to provide a method of making microbiologically contaminated water safe to drink. However this process has a number of shortcomings including susceptibility to the variability of weather conditions, for instance on cloudy days it could take significantly longer for sufficient inactivation to be achieved, often up to 48 hours or more. Allied to this, SODIS is effective primarily between the latitudes 35°N and 35°S, making it sub-optimal to many of the prospective markets including Northern Europe, North America, South America and Asia.

The inactivation mechanism for SODIS is complex and not yet fully understood. The central hypothesis is that UV-A light produces Reactive Oxygen Species (ROS) such as hydroxyl radical, super oxide radical anion, hydrogen peroxide, and singlet oxygen that play an important role. This can damage nucleic acids, proteins or other life supporting cell structures. It has also been found that broad spectrum UV-A light blocks the electron transport chain, inactivated transport systems interfere with metabolic energy production and can cause a general increase in permeability of the membrane.

The underlying process responsible for the inactivation is light dependent production of reactive forms of oxygen including oxygen free radicals such as super-oxide and hydroxyl radicals along with toxic derivations such as hydrogen peroxide. These Reactive Oxygen Species are generated mainly as a result of the absorption of light by endogenous photosensitizers e.g. intracellular porphyrins and flavins.

Studies have shown that the rate of inactivation of faecal bacteria (Escherichia coli) exposed to sunlight is 4-8 times faster in oxygenated water compared to hypo-oxygen water. This demonstrates that photo-oxidation is a reason for the rapid decrease in bacterial counts. Likewise, photo-inactivation rates decrease in the presence of hydrogen peroxide scavengers, whilst increasing in the presence of added hydrogen peroxide.

Some studies have been done to investigate strategies for improving SODIS methods which improve the microbiological inactivation performance, consistency of inactivation and reduce the reliance upon UV-A as the inactivation pathway.

In 'Speeding up solar disinfection (SODIS): effects of hydrogen peroxide, temperature, pH, and copper plus ascorbate on the photoinactivation of E. Coli', /. Water Health 6(1): 35-51, the authors investigated the use of a number of additives to speed up SODIS. Additives were added to water samples in PET bottles and left in both sunny and cloudy weather for various time periods before the levels of E. Coli in the samples were measured. Hydrogen peroxide is thought to react in an intracellular Fenton-type reaction. Fentons reaction is defined as the iron-dependent decomposition of hydrogen peroxide as shown in Reaction 1. Fe(III) is reduced to Fe(II) producing hydroxyl radicals and hydroxyl anions.

Fe^z+ + H₂0₂→ Fe³⁺ + ΟΗ· + OH Reaction 1 Hydroxyl radicals have the potential to oxidise cellular DNA, cell membranes and cell proteins for example, leading to inactivation of pathogens present in the water.

Other metal ions, such as Copper ions and Silver ions are also thought to participate in Fentons-like reactions.

Cu⁺ + H₂0₂→ Cu²⁺ + ΟΗ· + OH Reaction 2 In Water Disinfection with the Hydrogen Peroxide-Ascorbic Acid-Copper(II) System', Appl. Env. Micro. 44(3): 555-560, the authors used a combination of copper and ascorbic acid to disinfect water.

It would be desirable to provide an improved apparatus and method for decontamination of standing water including livestock drinking troughs and drinking vessesl, lakes, ponds, water features, swimming pools, and more generally for treatment of water for human or animal consumption.

Summary of the Invention

According to a first aspect of the invention, there is provided a water treatment apparatus comprising: a reaction chamber, the chamber comprising at least one inlet for allowing ingress of water into the reaction chamber and at least one outlet for allowing egress of water from the reaction chamber; a source of hydrogen peroxide; and means for dispensing hydrogen peroxide into the reaction chamber; and means for heating water located within the reaction chamber, wherein the means for heating the water comprises a lens.

Preferably the apparatus has an upper end and a lower end. In use the upper end is preferably located at or above the surface of the water to be treated. In use the lower end of the apparatus is located below the surface of the water to be treated.

Preferably the at least one inlet of the reaction chamber is located at the lower end of the apparatus.

Preferably the at least one outlet of the reaction chamber is located towards the upper end of the apparatus.

The apparatus may be configured to float in body of water being treated with the upper end of the apparatus located above the surface of the water. Parts of the apparatus may be designed or manufactured to give the apparatus sufficient buoyancy such that it floats in water. Alternatively, the apparatus may be further provided with floatation means. Floatation means could include a buoyant ring located around the apparatus, such as a foam ring or an inflatable ring. Flotation means are preferably located around the upper end of the apparatus. The apparatus may be tethered to vessel containing the water to be treated. Preferably the apparatus is self righting such that if knocked over it returns to an upright position, with the upper end of the apparatus located above the surface of the water.

Alternatively, the water treatment apparatus may be connectable to a vessel containing water to be treated in a fixed orientation. Alternatively, the water treatment apparatus may form an integral part of vessel containing water to be treated.

Preferably the lens is located at the upper end of the apparatus. Preferably, when the apparatus is in use the lens is located above the level of the water to be treated. Preferably the focal point of the lens is located within the reaction chamber. More preferably the focal point of the lens is located proximate the inlet of the reaction chamber. Any suitable lens may be used to focus solar energy to a point located within the reaction chamber such that the water held therein is heated. Preferably the lens is a Fresnel lens. Preferably the lens is fabricated from a material that is substantially transparent to UV light.

Preferably the apparatus also uses SODIS technology to inactivate pathogens in the water. SODIS uses the UV-A spectrum of sunlight to inactivate pathogens in the water. Preferably the lens captures UV-A light and directs it into the reaction chamber. More preferably the lens is a Fresnel lens which captures the maximum UV-A wavelength of light and directs it into the reaction chamber.

Preferably the water in the primary reaction chamber is heated to a temperature in the rang 20°C to 50°C. More preferably the water in the primary reaction chamber is heated to temperature in the range 20°C to 25°C. Preferably, the apparatus further comprises at least one additive storage tank. Preferably the or each additive storage tank comprises at least one outlet for dispensing additives contained within the or each additive storage tank into the reaction chamber. More preferably, the or each additive storage tank comprises dosing means for dispensing additives into the reaction chamber through the or each outlet at a controlled rate.

Preferably, the source of hydrogen peroxide is a solution of hydrogen peroxide which is contained within at least one additive storage tank. Preferably the solution of hydrogen peroxide is dispensed into the reaction chamber at a rate in the rangelOO μτηοΐ to 1000 μτηοΐ per hour. More preferably the solution of hydrogen peroxide is dispensed into the reaction chamber at a rate of 500 μτηοΐ per hour.

The use of hydrogen peroxide as a drinking water additive has been approved by the National Sanitation Foundation at concentrations of up to 880 μΜ. It has also been classified as Generally Regarded As Safe" by the USFDA for use in food processing and a s a food additive. Preferably, the apparatus further comprises a source of ascorbate ions and/or citrate ions and means for dispensing the ascorbate ions and/ or citrate ions into the reaction chamber.

Preferably the source of ascorbate ions is contained within at least one of the additive storage tanks. More preferably the source of ascorbate ions is a solution of ascorbic acid or a solution of an ascorbate salt. Preferably the solution of ascorbic acid or solution of an ascorbate salt is dispensed into the reaction chamber at a rate in the range 0 to 200 μτηοΐ per hour. More preferably the solution of ascorbic acid or solution of an ascorbate salt is dispensed into the reaction chamber at a rate of 37.5 μτηοΐ per hour. Preferably the source of citrate ions is contained within at least one of the additive storage tanks. More preferably the source of citrate ions is a solution of citric acid or a solution of a citric acid salt. Preferably the solution of citric acid or solution of a citric acid salt is dispensed into the reaction chamber at a rate in the range 0 to 200 μτηοΐ per hour. More preferably the solution of citric acid or solution of a citric acid salt is dispensed into the reaction chamber at a rate in the range 25 to 200 μτηοΐ per hour.

Preferably, the apparatus further comprises a source of metal ions that can participate in a Fentons-style reaction. More prefereably the metal ions are selected from the group comprising: copper ions, iron ions and silver ions. Most prefereably the apparatus further comprises a source of copper ions.

The source of copper ions may be a solution of a copper (II) salt contained within at least one of the additive storage tanks. The source of copper ions may be a solution of copper sulphate. Preferably the solution of a copper (II) salt is dispensed into the reaction chamber at a rate in the range 0.1 to 2.5 μτηοΐ per hour. More preferably the solution of a copper (II) salt is dispensed into the primary reaction chamber at a rate of 2.5 μτηοΐ per hour.

The source of copper ions may be copper metal located within the reaction chamber. Preferably the copper metal is located such that it may be exposed to sunlight. Preferably copper ions are dosed into the primary reaction chamber at a rate in the range 0 to 8 μτηοΐ per hour. Preferably the apparatus is configured such that the water to be treated is warmed prior to the introduction of the copper ions. Preferably the focal point of the lens is located below the source of copper ions. Preferably, the apparatus further comprises a source of ascorbate ions and/or citrate ions and a source of copper ions and means for dispensing each source of ions into the reaction chamber. More preferably the apparatus is configured to dispense the ascorbate ions and/ or citrate ions into the water to be treated prior to the addition of the copper ions. More preferably, the means for dispensing the ascorbate and/ or citrate ions is located closer to the inlet than the source of copper ions.

Preferably the water being treated remains within the apparatus for a period of time sufficient to de-activate the majority of bacteria, viruses, micro-organisms and/or parasites living within the water. The apparatus may further comprise a secondary chamber, the secondary chamber including at least one inlet for allowing ingress of water from the at least one outlet of the reaction chamber into the secondary chamber, and at least one outlet for allowing egress of water from the apparatus

The addition of a secondary chamber allows a longer residence time of the water being treated within the apparatus and also allows the treated water to be cooled prior to being remixed with the main body of water.

Preferably the secondary chamber is provided with a plurality of baffles. The baffles help increase the residence time of the water within the secondary chamber.

According to a further aspect of the invention, there is provided a vessel for containing a body of water to be treated comprising a water treatment apparatus as hereinbefore defined attached to the vessel. According to a further aspect of the invention, there is provided a vessel for containing a body of water to be treated comprising a water treatment apparatus as hereinbefore defined as an integral part of the vessel.

According to a further aspect of the invention, there is provided a service box for a water trough comprising a water treatment apparatus as hereinbefore defined.

According to a further aspect of the invention, there is provided a method of treating a volume of standing water comprising the steps of: a) placing water treatment apparatus as hereinbefore defined into the volume of standing water to be treated; and

b) leaving the apparatus in the water for a period of at least 24 hours.

Preferably the apparatus is located in direct sunlight for as long as possible. This allows sunlight, and more particularly, UV-A light, to enter the reaction chamber of the apparatus and utilises SODIS reaction pathways to inactivate pathogens in the water.

The water treatment apparatus of the present invention provides easy to use apparatus which can be used to improve the microbiological quality of standing water including livestock drinking troughs.

Brief Description of the Drawings

In the drawings, which illustrate preferred embodiments of a water treatment apparatus according to an embodiment of the invention: Figure 1 illustrates a perspective view of a water treatment apparatus according to an embodiment of the invention;

Figure 2 illustrates a side view of the water treatment apparatus of Figure 1 in a water trough, the trough shown in cross section; Figure 3 illustrates an exploded view of the water treatment apparatus shown in Figure 1;

Figure 4 illustrates a plan view of the water treatment apparatus of Figure 1;

Figure 5 illustrates a side view of the water treatment apparatus of Figures 1 to 3;

Figure 6 illustrates a sectional view of the apparatus of Figure 4, along the line B-B;

Figure 7 illustrates a sectional view of the apparatus of Figure 4, along the line A-A; Figure 8 illustrates a perspective view, from above of the apparatus of Figure 1, with Fresnel lens removed;

Figure 9 illustrates a perspective view, from below of the apparatus of Figure 1;

Figure 10 illustrates a perspective view of a water treatment apparatus according to a second embodiment of the invention; Figure 11 illustrates a side view of the water treatment apparatus shown in Figure 10;

Figure 12 illustrates an exploded view of the water treatment apparatus shown in Figures 10 and 11; Figure 13 illustrates a cross-sectional side view of a water trough with the water treatment apparatus of Figure 1 attached; and

Figure 14 illustrates a cross-sectional side view of a water trough with a water treatment apparatus attached within a service box.

Detailed Description of the Preferred Embodiments

Referring now to Figure 1, a water treatment apparatus is shown generally at 1. The apparatus 1 is generally circular in shape and is provided with a Fresnel lens 2 at its uppermost end. As shown in Figure 2, the apparatus 1 floats in a trough 31 of water 32 such that the uppermost end, including the Fresnel lens 2, remains above the surface of the water 32. Floatation of the apparatus 1 is either achieved through the design of parts of the apparatus to give it inherent buoyancy, or by the addition of separate floatation means (not shown) such as a buoyant ring located around the apparatus 1. The preferred water level is indicated generally at 18 in Figures 2 and 5.

The apparatus 1 comprises three additive storage tanks 3, 4, 5. Each tank is provided with an opening 6, 7, 8 for restocking of additives. In this example the first additive storage tank 3 is filled with a hydrogen peroxide solution; the second additive storage tank 4 is filled with a solution of an ascorbate salt, such as ascorbic acid, and the third additive storage tank 5 is empty. In an alternative embodiment of the invention the third additive storage tank 5 may be filled with a solution of a copper salt, such as copper sulphate. The apparatus 1 is provided with a water inlet tube 9 at its lowermost end. As shown in Figure 2, the inlet tube 9 preferably extends close to the base of the trough 30. Water from the trough enters the apparatus via this inlet tube 9 and enters a reaction chamber 10 (as described in more detail in relation to Figures 2, 4 and 5). The water inlet tube 9 may include a filter to prevent any solid matter from entering the apparatus 1. Convection currents set up during the treatment of the water 32 by the apparatus 1 cause water to circulate through the apparatus and consequently around the trough. Location of the inlet tube 9 close to the base of the trough 30 allows much more of the body of water 32 to be treated. Figure 3 shows an exploded view of the apparatus 1. The apparatus 1 comprises a reaction chamber 10 that is directly connected to the water inlet tube 9. The reaction chamber 10 is located beneath the Fresnel lens 2. As shown in Figure 6, the focal point 19 of the Fresnel lens 2 is located at a position within the reaction chamber 10, such that when the apparatus 1 is placed in sunlight the Fresnel lens 2 causes water located within the reaction chamber 10 to be heated. As shown, the focal point 19 of the Fresnel lens 2 is preferably located close to the lower end, or inlet, of the reaction chamber 10.

The reaction chamber 10 is also provided with additive inlet tubes 11, 12, 13 which are connected directly to additive outlets 14, 15, 16 on the additive storage tanks 3, 4, 5. The additive outlets 14, 15, 16 on the additive storage tanks 3, 4, 5 are connected to dosing means (not shown) that allow a slow, controlled release of additives from the storage tanks 3, 4, 5 into the reaction chamber 10. The reaction chamber 10 is provided with outlets 17 located towards the top end of the reaction chamber 10. The outlets 17 allow water to egress from the reaction chamber 10 into a secondary chamber 20. The second chamber 20 is located around the outside of the reaction chamber 10 and is generally disc shaped. The second chamber 20 is much wider in diameter than the reaction chamber 10 and is provided with an array of baffles 21 which are intended to increase the residence time of the water within the second chamber. Treated water exits the second chamber through exit ports 22 located on the outer wall 23 of the second chamber 20.

In this example the apparatus 1 is also provided with an array of copper metal rods 24 which are located towards the top of the reaction chamber 10, below the water level 18 and below the level of the reaction chamber outlets 17. In use, the copper metal rods 24 are submerged in water and in a location which will be exposed to sunlight.

As shown in Figure 6, the focal point 19 of the Fresnel lens 2 is preferably located below the level of the additive inlet tubes 11, 12, 13 and below the level of the copper metal rods 24. In addition, the additive inlet tubes 11, 12, 13 are preferably located below the level of the copper metal rods 24. This arrangement means that water enters the apparatus 1 via inlet tube 9 and is then heated at the focal point 19 of the Fresnel lens 2 as it enters the reaction chamber 10. The warmed water then rises through the apparatus and is dosed first with additives from the additive inlet tubes 11, 12, 13, and then subsequently passes over the copper metal rods 24.

As an alternative to the use of copper metal rods 24, the third additive storage tank 5 may be filled with a solution of a copper salt, for example copper sulphate. In use, the apparatus 1 floats in the body of water it is intended to treat, such as an agricultural water trough. For optimum results the apparatus 1 should be situated in full sunlight. Contaminated water enters the apparatus through the water inlet tube 9 and enters the reaction chamber 10. Water in the reaction chamber 10 is heated at the focal point 19 of the Fresnel lens. Heating the water in the reaction chamber 10 accelerates the biocidal reaction processes being carried out and also draws untreated water through the device. As the water in the reaction chamber 10 is warmed it rises and fresh, untreated, water is drawn into the apparatus through the water intake tube 9, creating convection currents in the water. Preferably the water is heated to at least 25°C. Metered doses of the hydrogen peroxide solution and ascorbic acid or citric acid solutions are dispensed into the reaction chamber 10 from the additive storage containers 3, 4 via the dosing means and the additive inlets 11, 12. As the warmed water mixes with the additives it rises towards the top of the reaction chamber 10 and as it passes over the array of copper metal rods 24 copper ions are added to the water. The synergistic effect of the warmed water, the hydrogen peroxide and ascorbate or citrate additives and the copper ions inactivates microbiological species within the water.

As the water reaches the top of the reaction chamber 10 it passes through outlets 17 and enters the second chamber 20. The baffles 21 located within the second chamber 20 help increase the residence time of the treated water within the apparatus 1. This allows time for the biocidal reaction processes to be completed and also helps to cool the water before it is mixed back into the trough. Temperature of the water in the trough may affect the palatability of the water.

The apparatus 1 may be used in a water trough containing in the region of 100 litres of water. For use in a water trough of this size the total volume of the reaction chamber 10 and the second chamber 20 is preferably approximately 1 litre and water to be treated preferably remains within the apparatus for a period of one hour. As an example, the first additive storage tank 3 may be filled with an 8% hydrogen peroxide solution, of which 0.21 ml (500μΜ) is dosed gradually throughout the course of each one hour period. The second additive storage tank 4 may be filled with a 5% aqueous ascorbic acid solution, of which 0.1ml (37.5μΜ) is dosed gradually throughout the course of each one hour period. Copper metal rods are preferably used as the source of copper ions.

Figures 10 to 12 illustrate an alternative embodiment of the apparatus of the invention. Identical features are referred to using identical reference numerals. This embodiment of the apparatus, shown generally at 30, is simpler in construction in that it comprises fewer additive storage tanks and does not include a second chamber. Instead, water from the reaction chamber 10 exits the apparatus directly back into the body of water being treated. As with the previous embodiment, the apparatus 30 is generally circular in shape and is provided with a Fresnel lens 2 at its uppermost end. The apparatus 30 floats in a trough of water such that the uppermost end, including the Fresnel lens 2, remains above the surface of the water. Floatation of the apparatus 1 is either achieved through the design of parts of the apparatus to give it inherent buoyancy, or by the addition of separate floatation means (not shown) such as a buoyant ring located around the apparatus 30. The apparatus 30 comprises one additive storage tank 25. The additive storage tank 25 is provided with an opening 26 for restocking of additives. In this example the additive storage tank 25 is filled with a hydrogen peroxide solution. The apparatus may be modified to provide more than one additive storage tank, as described in relation to the previous embodiment.

The apparatus 30 is provided with a water inlet tube 9 at its lowermost end. Water from the trough enters the apparatus via this inlet tube 9 and enters the reaction chamber 10. The water inlet tube 9 may include a filter to prevent any solid matter from entering the apparatus 30. Preferably the water inlet tube 9 extends close to the base of the trough containing the water to be treated, as illustrated in Figure 2 in relation to the previously described embodiment of the invention.

Figure 12 shows an exploded view of the apparatus 30. The apparatus 30 comprises a reaction chamber 10 that is directly connected to the water inlet tube 9. The reaction chamber 10 is located beneath the Fresnel lens 2. As with the previous embodiment, the focal point of the Fresnel lens 2 is located at a position within the reaction chamber 10, such that when the apparatus is placed in sunlight the Fresnel lens 2 causes water located within the reaction chamber 10 to be heated.

The reaction chamber 10 is also provided with an additive inlet tube 28 which is connected directly to an additive outlet 27 on the additive storage tank 27. The additive outlet 27 is connected to dosing means (not shown) which allows a slow, controlled release of additives from the storage tank 27 into the reaction chamber 10.

The reaction chamber 10 is provided with outlets 17 located towards the top end of the reaction chamber 10. The outlets 17 allow water to egress from the reaction chamber 10 back into the trough. In this example the apparatus 1 is also provided with an array of copper metal rods 24 which are located towards the top of the reaction chamber 10, below the water level 18 and below the level of the reaction chamber outlets 17. In use, the copper metal rods 24 are submerged in water and in a location which will be exposed to sunlight. As an alternative to the use of copper metal rods 24, a second additive storage tank may be included and filled with a solution of a copper salt, for example copper sulphate. This embodiment of the invention may also be modified to include additional storage tanks for citric acid/ascorbic acid additives as described in relation to the first embodiment.

In use, the apparatus 30 floats in the body of water it is intended to treat, such as an agricultural water trough. For optimum results the apparatus 30 should be situated in full sunlight. Contaminated water enters the apparatus through the water inlet tube 9 and enters the reaction chamber 10. Water in the reaction chamber 10 is heated at the focal point of the Fresnel lens 2. Heating the water in the reaction chamber 10 accelerates the biocidal reaction processes being carried out and also helps to draw untreated water through the device, setting up convection currents in the water. As the water in the reaction chamber 10 is warmed it rises and fresh, untreated, water is drawn into the apparatus through the water intake tube 9. Preferably the water is heated to at least 25°C. A metered dose of the hydrogen peroxide solution is dispensed into the reaction chamber 10 from the additive storage container 25 through the additive inlet tube 28. As the warmed water mixes with the hydrogen peroxide it rises towards the top of the reaction chamber 10 and as it passes over the array of copper metal rods 24 copper ions are added to the water. The synergistic effect of the warmed water, the hydrogen peroxide and the copper ions inactivates microbiological species within the water. The Fresnel lens also focuses UV-A light from the sunlight into the reaction chamber, meaning that SODIS reaction processes also take place in the reaction chamber to inactivate pathogens.

As the water reaches the top of the reaction chamber 1 it passes through outlets 17 and exits the apparatus. As an example, the additive storage tank 25 may be filled with an 8% hydrogen peroxide solution, of which 0.21 ml (500μΜ) is dosed gradually throughout the course of each one hour period.

Any of the embodiments of the water treatment apparatus as hereinbefore defined may be tethered or fixed to the water trough or other vessel containing the water to be treated. Alternatively, the apparatus may be provided as an integral part of the water trough or other vessel containing the water to be treated. As shown in Figure 13, the apparatus 1 may be secured directly to one of the sides of the water trough 31. The apparatus 1 could be secured using any suitable means, such as bolts or ties (not shown), or may be provided as an integral part of the water trough 31. The apparatus 1 is connected to the trough 31 such that the lens 2 is located above water level 18.

Alternatively, as shown in Figure 14, the apparatus 1' may be located within the service box

33 of the water trough 31. A service box for a water trough typically includes a ballcock and is connectable a mains water supply to keep the water trough filled with water. In this embodiment of the invention the service box 33 is adapted to include the water treatment apparatus of the invention and allows the water inlet tube 9 to pass through the base of the service box 33 and into the water 32. The apparatus 1' is adapted to include an outlet pipe

34 which passes through the side wall of the service box 33 and allows egress of treated water from the secondary chamber 20 of apparatus back into the trough 31. At least the lens 2 must emerge from the top of the service box 33 to allow it to be exposed to sunlight. The lens 2 is located above the water level 18.

Claims

1. Water treatment apparatus comprising: a reaction chamber, the reaction chamber comprising at least one inlet for allowing ingress of water into the reaction chamber and at least one outlet for allowing egress of water from the reaction chamber; a source of hydrogen peroxide; means for dispensing hydrogen peroxide into the at reaction chamber; and means for heating water located within the reaction chamber, wherein the means for heating the water in the reaction chamber comprises a lens.

2. Water treatment apparatus according to any preceding claim, wherein the apparatus has an upper end and a lower end and in use the upper end is located at or above the surface of the water to be treated.

3. Water treatment apparatus according to claim 2, wherein the at least one inlet of the reaction chamber is located at the lower end of the apparatus.

4. Water treatment apparatus according to any preceding claim, wherein the lens is located at the upper end of the apparatus.

5. Water treatment apparatus according to any preceding claim, wherein the focal point of the lens is located within the reaction chamber.

6. Water treatment apparatus according to any preceding claim, wherein the focal point of the lens is located proximate to the inlet of the reaction chamber.

7. Water treatment apparatus according to any preceding claim, wherein in use the apparatus floats in the body of water to be treated.

8. Water treatment apparatus according to any of Claims 1 to 7, wherein the water to be treated is containable within a vessel and the water treatment apparatus is connectable to the vessel.

9. Water treatment apparatus according to any of Claims 1 to 7, wherein the water to be treated is containable within a vessel and the water treatment apparatus forms an integral part of the vessel.

10. Water treatment apparatus according to any preceding Claim, wherein the water in the reaction chamber is heated to a temperature in the range 20°C to 50°C.

11. Water treatment apparatus according to any preceding Claim, further comprising at least one additive storage tank.

12. Water treatment apparatus according to Claim 11, wherein the or each additive storage tank comprises at least one outlet for dispensing additives contained within the or each additive storage tank into the reaction chamber.

13. Water treatment apparatus according to Claim 12, wherein the or each additive storage tank comprises dosing means for dispensing additives into the reaction chamber through the or each outlet at a controlled rate.

14. Water treatment apparatus according to any of Claims 11 to 13, wherein the source of hydrogen peroxide is a solution of hydrogen peroxide located within at least one additive storage tank.

15. Water treatment apparatus according to Claim 14, wherein the solution of hydrogen peroxide is dispensed into the reaction chamber at a rate in the rangel00μmol to 1000 μτηοΐ per hour.

16. Water treatment apparatus according to any preceding claim, further comprising a source of ascorbate ions and/ or citrate ions and means for dispensing the ascorbate ions and/ or citrate ions into the reaction chamber.

17. Water treatment apparatus according to Claim 16, wherein the source of ascorbate ions is a solution of ascorbic acid located within at least one additive storage tank.

18. Water treatment apparatus according to Claim 17, wherein the solution of ascorbic acid is dispensed into the reaction chamber at a rate in the range 0 to 200μιτιο1 per hour.

19. Water treatment apparatus according to any preceding claim, further comprising a source of copper ions.

20. Water treatment apparatus according to Claim 19, wherein the source of copper ions is a solution of a copper (II) salt located within an additive storage tank.

21. Water treatment apparatus according to Claim 20, wherein the solution of a copper (II) salt is dispensed into the reaction chamber at a rate in the range 0.1 to 2.5μτηο1 per hour.

22. Water treatment apparatus according to Claim 19, wherein the source of copper ions is copper metal and the copper metal is located within the reaction chamber.

23. Water treatment apparatus according to any preceding claim, further comprising a secondary chamber, the secondary chamber including at least one inlet for allowing ingress of water from the at least one outlet of the reaction chamber into the secondary chamber, and at least one outlet for allowing egress of water from the apparatus.

24. Water treatment apparatus according to Claim 23, wherein the secondary chamber is provided with a plurality of baffles.

25. A vessel for containing a body of water to be treated comprising a water treatment apparatus according to any of Claims 1 to 24 attached to the vessel.

26. A vessel for containing a body of water to be treated comprising a water treatment apparatus according to any of Claims 1 to 24 as an integral part of the vessel.

27. A service box for a water trough comprising a water treatment apparatus according to any of Claims 1 to 24.

28. A method of treating a volume of standing water comprising the steps of: c) placing water treatment apparatus according to any of Claims 1 to 24 into the volume of standing water to be treated; and

d) leaving the apparatus in the water for a period of at least 24 hours.

29. A water treatment apparatus substantially as shown in and described with reference to the drawings.