WO2006106363A2

WO2006106363A2 - Fluid disinfection apparatus and system

Info

Publication number: WO2006106363A2
Application number: PCT/GB2006/050076
Authority: WO
Inventors: Malcolm Robert Snowball
Original assignee: Malcolm Robert Snowball
Priority date: 2005-04-08
Filing date: 2006-04-03
Publication date: 2006-10-12
Also published as: GB2424877A; WO2006106363A3; GB0507082D0; EP1865997A2; CA2604141A1

Abstract

Fluid disinfection apparatus (10) comprising a reservoir (12) for holding fluid (20) to be disinfected, a cylindrical roller member (14) and an array of (12) ultra violet lamps (16). The roller member (14) is partly received within the reservoir (12) and is thus partly submerged in the fluid (20). As the roller member (14) rotates (as indicated by the arrows), fluid (20) is picked up by the surface of the roller member (14) from the reservoir (12). The fluid (20) is dispersed into a film of fluid (20) across the surface (34a). The ultra violet (UV) lamps (16) are mercury arc discharge lamps which output UV light (10) including germicidal wavelengths: 220nm to 280nm. Exposure of the fluid film to the UV light kills or inactivates any micro-organisms within the fluid (20).

Description

FLUID DISINFECTION APPARATUS AND SYSTEM

The invention relates to fluid disinfection apparatus, a fluid disinfection system incorporating the apparatus and a method of disinfecting a fluid.

It is well known that high intensity ultra violet (UV) light has germicidal properties that can be used to disinfect water; EP0202891 discloses a device which utilizes these properties. The germicidal effect of UV light occurs when UV light is transmitted through a liquid, resulting in the disruption of the DNA of any micro-organisms within the liquid and thereby killing or inactivating the micro-organisms.

Known UV light based disinfection systems can be used on liquids having a transmissivity (the percentage of incident light transmitted through 10mm of the liquid) of between about 20% and 90%. Drinks and beverage producers often pack and sell liquids which routinely have transmissivities as low as 2% measured over a 1 mm distance through the liquid (i.e. 98% of incident light is absorbed after transmission through 1 mm of the liquid). Conventionally, low transmissivity liquids, such as fruit juices and post-mix beverage syrups, have to be thermally pasteurized; this process requires large amounts of energy and results in a degradation in the taste of the liquid. Known UV light disinfection techniques, such as that disclosed in EP0202891 , cannot satisfactorily disinfect these types of liquids. The accepted view is therefore that UV disinfection is not practical for such low transmissivity liquids, since it would require the use of extremely high power UV light combined with a very low processing rate.

According to a first aspect of the present invention there is provided fluid disinfection apparatus comprising: a reservoir for holding a fluid to be disinfected; fluid dispersal means operable to remove fluid from the reservoir and disperse the removed fluid; and an ultra violet light source operable to irradiate at least part of the dispersed fluid with ultra violet light.

The fluid dispersal means is preferably operable to disperse the removed fluid into a film of fluid. The fluid dispersal means preferably comprises a rotatably mounted surface in fluid communication with the reservoir, rotation of the surface causing the removed fluid to be dispersed into a film across the surface. The fluid dispersal means preferably further comprises drive means coupled to the rotatably mounted surface and operable to cause rotation of the rotatably mounted surface at a desired speed. The speed of rotation is preferably variable.

The rotatably mounted surface preferably comprises the surface of a substantially cylindrical roller member. The roller member is preferably made of a non-corrosive material, such as stainless steel. The roller member is preferably rotatably mounted on a centrally located drive shaft coupled to the drive means. The roller member is preferably partly received within the reservoir, such that, when fluid is present within the reservoir, the roller member is partly submerged in the fluid. The roller member is preferably additionally movably mounted such that the amount of the roller member received within the reservoir may be varied, most preferably in response to the depth of fluid within the reservoir.

The reservoir preferably comprises a storage part and a sump part, in fluid communication with the storage part, within which the roller member is partly received, rotation of the roller member within the sump part causing fluid to adhere to the surface of the roller member and be dispersed into a film across the surface of the roller member. The sump part is preferably of a complimentary size and shape to the part of the roller member to be received within it. Preferably, a fluid inlet, a maximum fluid level indicator and a minimum fluid level indicator are provided within the storage part, the fluid level indicators controlling the flow of fluid into the reservoir through the inlet.

The fluid dispersal means may further comprise film thickness control means. The film thickness control means preferably comprises first wiper means provided above the fluid level of the reservoir at a rotational position close to the point at which the surface of the roller member emerges from the fluid within the reservoir, and at a distance from the surface of the roller member equal to a desired film thickness, such that as the roller member emerges from the reservoir any surplus fluid adhering to its surface is wiped off by the first wiper means, thereby ensuring that the fluid film is of a desired thickness. The film thickness control means may alternatively comprise a part-cylindrical film thickness control member provided adjacent to and spaced from the roller member, the film thickness control member being of a complimentary size and shape to the roller member, and the separation between the film thickness control member and the roller member defining the thickness of the fluid film on the surface of the roller member. The film thickness control member preferably extends around substantially all of the part of the roller member not received within the reservoir. The film thickness control member is preferably provided between the roller member and the ultra violet light source and is made of an ultra-violet transparent material, such as quartz.

The fluid disinfection apparatus preferably further comprises fluid collection means comprising second wiper means acting against the surface of the roller member and a fluid outlet conduit into which fluid wiped off the roller member is delivered by the second wiper means. The second wiper means is preferably provided above the fluid level of the reservoir at a rotational position close to the point at which the surface of the roller member enters the fluid within the reservoir.

The or each wiper means may comprise a solid blade, preferably of stainless steel. The stainless steel blade is preferably provided with a contact portion for contact with the rotatably mounted surface, the contact portion being of a non-binding contact material, such as polytetrafluoroethylene. The or each wiper means may alternatively comprise a flexible blade, preferably of polytetrafluoroethylene, neoprene, natural rubber or silicone rubber, or may comprise an air knife.

The rotatably mounted surface may alternatively comprise the surface of a rotatably mounted plate, most preferably a disc. The rotatably mounted disc is preferably made of a non-corrosive material, such as stainless steel. One or more generally annularly shaped weir members may be provided on the surface of the rotatably mounted plate, to promote mixing of the fluid as it disperses across the surface of the plate.

The fluid dispersal means preferably further comprises fluid delivery apparatus extending in fluid communication between the reservoir and the rotatably mounted plate. The fluid delivery apparatus preferably comprises a fluid outlet conduit connected at one end to the rotatably mounted surface and a fluid delivery conduit in fluid communication between the reservoir and the fluid outlet conduit. The fluid outlet conduit preferably has a plurality of fluid outlet apertures provided towards its one end through which fluid is delivered to the surface of the rotatably mounted surface. The fluid outlet conduit is preferably coupled to the drive means, such that rotation of the fluid outlet conduit causes rotation of the rotatably mounted plate.

The fluid delivery apparatus preferably further comprises a collar member provided on the rotatably mounted surface, the collar member extending around and being spaced from the fluid outlet conduit, and the collar member having a plurality of secondary fluid outlet apertures provided therein, such that fluid exiting the fluid outlet conduit is caught by the collar member and then delivered to the rotatably mounted surface via the secondary fluid apertures.

The fluid dispersal means may further comprise film thickness control means comprising a film thickness control member provided adjacent to and spaced from the rotatably mounted plate, the film thickness control member being an annular plate of a complimentary size and shape to the rotatably mounted plate, and the separation between the film thickness control member and the rotatably mounted plate defining the thickness of the fluid film on the surface of the rotatably mounted plate. The film thickness control member preferably extends across substantially the whole rotatably mounted plate, with a centrally located hole within which the fluid outlet conduit and the collar member are located. The film thickness control member is preferably provided between the rotatably mounted plate and the ultra violet light source and is made of an ultra-violet transparent material, such as quartz.

The fluid disinfection apparatus preferably further comprises fluid collection means comprising a hopper member within which the rotatably mounted plate is provided, the hopper member having a greater diameter than the rotatably mounted plate such that fluid leaving the edge of the rotatably mounted plate is collected within the hopper member. The hopper member is preferably generally funnel shaped, and includes a fluid outlet conduit. The fluid disinfection apparatus may comprise a plurality of rotatably mounted plates, fluid delivery apparatus and fluid collection means, a first fluid outlet conduit being provided in fluid communication with the fluid delivery conduit of a subsequent fluid delivery apparatus.

Preferably the plates are arranged in a stack with fluid preferably flowing from one to the other under the influence of gravity.

Preferably the plates are formed of a material which is substantially transparent to the germicidal wavelengths. Suitable materials include Quartz, Teflon FEP etc. Lamps are preferably disposed between adjacent discs, so as to irradiate the rear surface of one disc and the front surface of another disc. In this manner, the films are irradiated from both sides and the throughput would increase for the same amount of power.

Further alternatively, the fluid dispersal means may comprise a plurality of roller members arranged in fluid communication in a spaced series; the first roller member of the series being in fluid communication with the reservoir and rotation of the first roller member causing fluid to be removed from the reservoir and dispersed into a film across the surface of the first roller member; and rotation of a subsequent roller member of the series causing the fluid to be removed from the previous roller member of the series and dispersed into a film across the surface of the subsequent roller member. Each roller member is preferably made of a non-corrosive material, such as stainless steel.

Preferably, adjacent roller members within the series rotate in opposite senses, such that as fluid is transferred from one roller member to the subsequent roller member the fluid undergoes mixing.

The fluid disinfection apparatus preferably further comprises fluid collection means comprising wiper means acting against the surface of the final roller member within the series and a fluid outlet conduit into which fluid wiped off the roller member is delivered by the wiper means. The wiper means may comprise a solid blade, preferably of stainless steel. The stainless steel blade is preferably provided with a contact portion for contact with the rotatably mounted surface, the contact portion being of a non-binding contact material, such as polytetrafluoroethylene. The wiper means may alternatively comprise a flexible blade, preferably of polytetrafluoroethylene, neoprene, natural rubber or silicone rubber, or may comprise an air knife.

Preferably, a fluid inlet, a maximum fluid level indicator and a minimum fluid level indicator are provided within the fluid reservoir, the fluid level indicators controlling the flow of fluid into the reservoir through the inlet.

The fluid reservoir is preferably made of a non-corrosive material, such as stainless steel.

The or each rotatably mounted surface may be an optically reflective surface. The or each rotatably mounted surface may be a polished surface. Alternatively, the or each rotatably mounted surface may be provided with an optically reflective coating. The or each rotatably mounted surface may alternatively or additionally be provided with a photo-catalytic oxidizing coating, most preferably anataise titanium dioxide. The or each rotatably mounted surface may be patterned or roughened in order to improve the adhesion of low viscosity fluids thereon.

The or each rotatably mounted surface may be porous, such that air may be delivered through the porous surface to form air bubbles within a film of fluid present on the surface, to thereby increase the transmissivity of the fluid.

Alternatively or additionally, the fluid disinfection apparatus may comprise air dilution means operable to deliver air bubbles into the fluid within the reservoir. The air dilution means preferably comprises a high pressure chamber into which part of the fluid within the reservoir is delivered, an air compressor operable to deliver pressurised air into the fluid within the high pressure chamber, the air being at least partially dissolved within the fluid, and a delivery nozzle through which the fluid containing at least partially dissolved air is released back into the reservoir, the at least partially dissolved air thereby forming into air bubbles within the fluid.

The ultra violet light preferably includes one or more wavelengths within the range 220 to 280 nanometres, being germicidal ultra violet wavelengths. The ultra violet light source preferably comprises an ultra violet lamp, and most preferably comprises a plurality of ultra violet lamps. The or each ultra violet lamp preferably comprises a mercury arc discharge lamp. The or each ultra violet lamp is preferably provided within a protective housing of an ultra violet transparent material, such as quartz.

The or each ultra violet lamp is preferably located substantially adjacent its respective rotatably mounted surface, such that output of the or each lamp illuminates the surface. The or each ultra violet lamp is preferably movably mounted to enable removal of the or each lamp for inspection and/or cleaning.

The or each ultra violet lamp is preferably mounted within a movably mounted lighting assembly, the lighting assembly being of an ultra violet non-transmitting material to ensure that all of the ultra violet light is retained within the fluid disinfecting apparatus. The lighting assembly preferably comprises a reflective element provided behind each ultra violet lamp, to reflect incident ultra violet light towards the rotatably mounted optical surface.

Preferably means are provided for agitating the dispersed film of fluid.

The agitating means may comprise one or more members which project towards said rotatably mounted surface. Alternatively, said rotatably mounted surface may be profiled, e.g. with ridges, which agitate the fluid as the surface rotates.

Preferably means are provided for measuring the thickness of the film and for controlling the speed of rotation of the rotatably mounted surface and/or for controlling the position of film thickness control means.

According to a second aspect of the invention there is provided a fluid disinfection system comprising: a first fluid storage tank having a first fluid inlet/outlet aperture; a second fluid storage tank having a second fluid inlet/outlet aperture; fluid disinfection apparatus according to the first aspect of the invention; a first fluid flow path extending from the first fluid inlet/outlet aperture to the fluid disinfection apparatus reservoir fluid inlet; a second fluid flow path extending from the fluid disinfection apparatus collection means outlet to the second fluid inlet/outlet aperture; a third fluid flow path extending from the second fluid inlet/outlet aperture to the fluid disinfection apparatus reservoir fluid inlet; and a fourth fluid flow path extending from the fluid disinfection apparatus collection means outlet to the first fluid inlet/outlet aperture, such that fluid may be transferred from the first fluid storage tank to the second fluid storage tank via the fluid disinfection apparatus, and vice versa, thereby enabling fluid to undergo multiple passes through the fluid disinfection apparatus.

According to a third aspect of the invention there is provided a method of disinfecting a fluid, the method comprising: dispersing the fluid into a film; and irradiating at least part of the fluid film with ultraviolet light. The method may further comprise the step introducing air bubbles into the fluid to increase the transmissivity of the fluid.

Embodiments of the invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic representation of fluid disinfection apparatus according to a first embodiment of the invention;

Figure 2 is a diagrammatic representation of fluid disinfection apparatus according to a second embodiment of the invention;

Figure 3 is a diagrammatic representation of fluid disinfection apparatus according to a third embodiment of the invention;

Figure 4 is a diagrammatic representation of fluid disinfection apparatus according to a fourth embodiment of the invention;

Figure 5 is a diagrammatic representation of fluid disinfection apparatus according to a fifth embodiment of the invention; Figure 6 is a diagrammatic representation of fluid disinfection apparatus according to a sixth embodiment of the invention;

Figure 7 is a diagrammatic representation of fluid disinfection apparatus according to a seventh embodiment of the invention; and

Figure 8 is a diagrammatic representation of a fluid disinfection system according to an eighth embodiment of the invention; and

Figure 9 is a diagrammatic representation of fluid disinfection apparatus according to a ninth embodiment of the invention.

Referring to Figure 1 , fluid disinfection apparatus 10 according to a first embodiment of the invention comprises a reservoir 12 for holding fluid 20 to be disinfected, fluid dispersal means in the form of a cylindrical roller member 14 and an ultra violet light source in the form of an array of 12 ultra violet lamps 16.

The reservoir 12 is fabricated from a non-corrosive material, in this example stainless steel, and comprises a storage part 12a, a sump part 12b and a lid 12c. The storage part 12a and the sump part 12b are in fluid communication with one another via a submerged weir 18 over which fluid 20 can flow into the sump part 12b from the storage part 12a.

The roller member 14 is partly received within the sump part 12b and is thus partly submerged in the fluid 20. The sump part 12b is substantially part-cylindrical in shape, being of a complimentary size and shape to the part of the roller member 14 to be received within it. The shape of the sump part 12b encourages fluid 20 within the sump part 12b to mix as the roller member 14 rotates.

The storage part 12a is provided with a fluid inlet 22 through which fluid 20 to be disinfected is delivered to the fluid disinfection apparatus 10. A maximum fluid level indicator 24 and a minimum fluid level indicator 26 are provided within the storage part 12a, for controlling the level of fluid 20 within the storage part 12a. The lid 12c is provided over the storage part 12a and has an exhaust hole 28 provided therein. The roller member 14 is approximately 1 m in length and has an outer diameter of 1 m. The roller member 14 is rotatably mounted on a central drive shaft 30 coupled to drive means (not shown) operable to rotate the roller member 14 at a desired speed. In this example, the roller member 14 is rotated at up to 120 revolutions per minute (rpm). The drive shaft 30 is support at each end on bearings (not shown) to allow the drive shaft 30 to rotate freely. The drive shaft 30 is provided on movable mountings 32 at each end, the movable mountings 32 being movably up and down to raise and lower the roller member 14; the proportion of the roller member 14 submerged in the fluid 20 can thereby be controlled.

The roller member 14 is made of a non-corrosive material, which in this example is stainless steel. In this example, the roller member 14 is substantially hollow, for lightness. The surface 14a of the roller member 14 is provided with a coating 34 of anataise titanium dioxide, which is both optically reflective in the ultra violet part of the optical spectrum and is a photo catalytic oxidising material which is activated on exposure to ultra violet light of a germicidal wavelength. The surface 34a of the coating 34 forms the rotatably mounted surface of the fluid disinfection apparatus 10.

As the roller member 14 rotates (as indicated by the arrows in Figure 1 ), fluid 20 is picked up by the surface 34a of the coating 34 from the sump part 12 of the reservoir 12. The fluid 20 is thereby formed into a film of fluid 20 across the surface 34a; the fluid film is held in place on the surface 34a by the surface tension of the fluid film.

The ultra violet (UV) lamps 16 comprise mercury arc discharge lamps which output ultra violet light including germicidal wavelengths: 220nm to 280nm. Each UV lamp 16 is tubular in shaped and is provided within a protective sleeve 40 of a material which is substantially transparent to UV radiation, in this example quartz.

The UV lamps 16 are mounted on a lighting assembly 42, each UV lamp 16 being located within an elongate, part-cylindrical recess 44 the internal surface of which is optically reflective; any UV light emitted in the direction towards the lighting assembly 42 is thereby reflected towards the fluid 20 to be disinfected. The UV lamps 16 are positioned at a set distance from the roller member 14 such that the UV light is of substantially uniform intensity across the exposed part of the roller member 14. The lighting assembly 42 head is movably mounted, via a hinge 46, to allow access to the UV lamps 16 and the roller member 14 for maintenance and cleaning. The lighting assembly 42, when closed (as shown), acts as a guard for the roller member 14 and the UV lamps 16 to prevent physical contact with the rotating roller member 14, and to protect an operator from any fluid spray and from the UV radiation emitted by the lamps 16. The lighting assembly 42 is made of a material opaque to UV radiation but transparent to visible radiation, thereby permitting visual inspection of the fluid disinfection apparatus 10 during use.

The lighting assembly 42 forms a substantially airtight enclosure 48 around the roller member 14 and the reservoir sump part 12b. A fan (not shown) is mounted through the side of the lighting assembly and directs a flow of air through the enclosure 48, from the fan to the fluid outlet 38 and the exhaust hole 28. The enclosure 48 is thereby exposed to positive air pressure, thereby ensuring that the UV lamps 16 are kept clean of fluid spray and preventing back contamination of the fluid disinfection apparatus 10 with external air. The air within the enclosure 48 is itself substantially disinfected by the UV light, and therefore does not introduce any biological contaminants into the fluid disinfection apparatus 10.

Fluid collection means in the form of an air knife 36 and a fluid outlet conduit 38 are provided for removing disinfected fluid 20 from the surface 34a of the coating 34. The air knife 36 comprises a porous blade through which air is delivered as a thin, intense jet of air. The air knife 36 is located just above the sump part 12b of the reservoir 12, at a point just before the surface of the roller member 14 enters the fluid 20. The air jet output from the air knife 36 acts against the rotatably mounted surface 34a to wipe disinfected fluid from the surface 34a. The removed fluid 20 is collected by the fluid outlet conduit 38.

In operation, fluid 20 to be disinfected is delivered into the storage part 12a of the reservoir 12 via fluid inlet 22. The fluid 20 then flows from the storage part 12a over the weir 18 into the sump part 12b. As the roller member 14 rotates, it picks up fluid

20 from the sump part 12b, and disperses the fluid 20 into film of fluid 30 across the surface 34a of the coating 34 on the surface 14a of the roller member 14. In this embodiment the fluid 20 is dispersed into a 0.5-0.7 mm thick film. The thickness of the film of fluid 20 may be controlled by varying the speed of rotation of the roller member 14, so that a constant film thickness can be produced for fluids of different viscosity.

As the roller member 14 rotates, the fluid film is exposed to the UV light emitted by the UV lamps 16 and the UV light penetrates the fluid sufficiently to destroy or deactivate any biological organisms present. Further disinfection of the fluid is provided by the photo catalytic oxidising effect of the titanium dioxide coating 34.

The thin film of now disinfected fluid is removed from the rotatably mounted surface 34a by the air knife 36 and flows out of the fluid disinfection apparatus through the outlet conduit 38. The fluid disinfection apparatus 10 of this embodiment can process up to 10 cubic meters of fluid per hour, depending upon the viscosity of the fluid.

Figure 2 shows fluid disinfection apparatus 50 according to a second embodiment of the invention. The apparatus 50 of this embodiment is substantially the same as the apparatus 10 of the previous embodiment, with the following modifications.

In this embodiment, the fluid dispersal means further comprises film thickness control means in the form of a stainless steel wiper 52 having a non-binding contact region in the form of a polytetrafluoroethylene (PTFE) contact tip. The wiper 52 is provided above the fluid level of the reservoir 12 close to the point at which the surface of the roller member 14 emerges from the fluid 20 within the sump part 12b of the reservoir 12. The contact tip of the wiper 52 is separated from the surface of the roller member 14 by a distance equal to a desired film thickness. As the roller member 14 emerges from the reservoir 12 any surplus fluid 20 adhering to its surface 14a is wiped off by the wiper 52, thereby ensuring that the fluid film is of a desired thickness.

The surface of the roller member 14 is polished to an optically reflective finish. The fluid collection means in this example takes the form of second stainless steel wiper 54 and a fluid outlet conduit 38. The second wiper 54 is biased against the surface 14a of the roller member 14, such that as the roller member 14 rotates, any fluid present on the surface 14a of the roller member 14 is wiped off by the wiper 54 and delivered to the fluid outlet conduit 38. Fluid disinfection apparatus 60 according to a third embodiment of the invention is shown in Figure 3. The apparatus 60 of this embodiment is substantially the same as the apparatus 10 of the first embodiment, with the following modifications.

In this embodiment, the fluid disinfection apparatus 60 additionally comprise air dilution means 62 operable to deliver air bubbles 64 into the fluid 20 within the sump part 12b reservoir 12. The air dilution means 62 comprises a high pressure chamber 64, an air compressor 66 and an outlet nozzle 68.

A fluid inlet conduit 70 extends from the storage part 12a of the reservoir 12 to the high pressure chamber 64 and delivers a small amount of fluid 20a into the high pressure chamber 64 from the reservoir 12.

The air compressor 66 is operable to generate pressurised air having a pressure of approximately 6 bar, which is delivered through an air delivery conduit 72 into the fluid 20a within the high pressure chamber 64. The high pressure air is at least partially dissolved within the fluid 20a within the high pressure chamber 64.

A fluid outlet conduit 74 delivers the fluid 20a containing at least partially dissolved air to the outlet nozzle 68. The outlet nozzle 68 is provided within the sump part 12b of the reservoir 12. As the fluid 20a is released back into the reservoir 12, the pressure under which the fluid 20a is maintained is reduced back to atmospheric pressure, and the at least partially dissolved air forms into air bubbles 76 within the fluid 20 within the sump part 12b of the reservoir 12. The air bubbles 76 remain within the fluid 20 as it is dispersed into a fluid film 78 on the surface 14a of the roller member

14 and as the fluid film 78 is carried round by the rotating roller member 14 to the air knife 36.

The presence of the air bubbles 76 within the fluid film 78 increases the transmissivity of the fluid 20 within the film 78 by up to 30-40%.

In this embodiment the roller member 14 must rotate approximately 20% faster than for the first embodiment, or the roller member 14 must be approximately 20% longer, in order to process the fluid quickly enough to retain the bubbles 76 within the fluid 20 for the duration of the UV exposure. Fluid disinfection apparatus 80 according to a fourth embodiment of the invention is shown in Figure 4. The apparatus 80 of this embodiment is substantially the same as the apparatus 10 of the first embodiment, with the following modifications.

In this embodiment, the roller member 82 comprises a hollow cylinder of sintered stainless steel. The drive shaft 84 is hollow at one end and fitted with a rotating airtight seal (not shown). An air outlet aperture is provided on the hollow section of the drive shaft. A fan (not shown) is provided to deliver pressurised air into the drive shaft 84, and through the air outlet aperture into the hollow roller member 82. The pressurised air passes through the sintered stainless steel of the roller member 82 and either into the fluid 20 within the sump part 12b of the reservoir 12, or into a fluid film 78 on the surface of the roller member 14. The pressurised air is thereby formed into small bubbles 76 within the fluid 20 and the fluid film 78.

Fluid disinfection apparatus 90 according to a fifth embodiment of the invention is shown in Figure 5. The apparatus 90 comprises a reservoir 92 for holding fluid 94 to be disinfected, fluid dispersal means in the form of a series of four cylindrical roller members 96, 98, 100, 102 and an ultra violet light source in the form of two arrays 104, 106 of ultra violet lamps 108.

The reservoir 92 is fabricated from a non-corrosive material, in this example stainless steel. The reservoir 92 is generally funnel-shaped, being open at the bottom (as shown in the drawing). Fluid 94 is delivered into the reservoir 92 via a fluid inlet 110. The level of fluid 94 within the reservoir 92 is controlled by a maximum level indicator 1 12. The bottom of the reservoir 92 is in fluid communication with the first roller member 96 and forms a gravity fed outlet 1 16 through which fluid 94 is delivered to the first roller member 96. A seal 118 is provided along one side of the outlet 116 and fluid thickness control means in the form of a stainless steel gate 121 is movably mounted along the other side of the outlet 1 16, such that the thickness of the fluid film formed on the first roller member 96 may be controlled.

Each roller member 96, 98, 100, 102 is approximately 1 m in length and has an outer circumference of 1 m. The roller members 96, 98, 100, 102 are rotatably mounted on central drive shafts 1 14 coupled to drive means (not shown) operable to rotate the roller members 96, 98, 100, 102 at a desired speed. In this example, the roller members 96, 98, 100, 102 are rotated at up to 120 revolutions per minute (rpm). The drive shafts 114 are support at each end on bearings (not shown) to allow the drive shafts 114 to rotate freely.

Each roller member 96, 98, 100, 102 is made of a non-corrosive material, which in this example is stainless steel. In this example, the roller members 96, 98, 100, 102 are substantially hollow, for lightness. The surfaces of the roller members 96, 98, 100, 102 coated with anataise titanium dioxide.

As the first roller member 96 rotates, fluid 94 is collected from the reservoir 92 by the surface of the coating on the first roller member 96. The fluid 94 is thereby dispersed into a film of fluid on the first roller member 96; the fluid film is held in place on the first roller member 96 by the surface tension of the fluid film.

Each roller member 96, 98, 100, 102 rotates in the opposite sense to its adjacent roller member or members, thereby causing a film of fluid 94 present on a first roller member to be transferred onto the following roller member. The roller members 96, 98, 100, 102 are arranged in a spaced relationship with one another. The distance between adjacent roller members 96, 98, 100, 102, together with the counter rotation of adjacent roller members 96, 98, 100, 102, causes fluid 94 being transferred from one roller member to the next to be mixed during transfer. The drive shafts 1 14 of the roller members 96, 98, 100, 102 are movably mounted to allow the distance between adjacent roller members 96, 98, 100, 102 to be adjusted for fluids of different viscosities.

The ultra violet (UV) lamps 108 comprise mercury arc discharge lamps which output ultra violet light including germicidal wavelengths: 220nm to 280nm. Each UV lamp 108 is tubular in shaped and is provided within a protective quartz sleeve 120.

The UV lamps 108 of the first array 104 are mounted on a first lighting assembly 122 and the UV lamps 108 of the second array 106 are mounted on a second lighting assembly 124. Each UV lamp 108 is mounted within an elongate, part-cylindrical recess 126 the internal surface of which is optically reflective; any UV light emitted in the direction towards a lighting assembly 122, 124 is thereby reflected towards the roller members 96, 98, 100, 102. The UV lamps 108 are positioned at a set distance from the roller members 96, 98, 100, 102 such that the UV light is of substantially uniform intensity across each roller member 96, 98, 100, 102.

The lighting assemblies 122, 124 are movably mounted to allow access to the UV lamps 108 and the roller members 96, 98, 100, 102 for maintenance and cleaning. The lighting assemblies 122, 124 when closed (as shown), act as a guard for the roller members 96, 98, 100, 102 and the UV lamps 108 to prevent physical contact with the rotating roller members 96, 98, 100, 102, and to protect an operator from any fluid spray and from the UV radiation emitted by the lamps 108. The lighting assemblies 122, 124 are made of a material opaque to UV radiation but transparent to visible radiation, thereby permitting visual inspection of the fluid disinfection apparatus 90 during use.

Fluid collection means in the form of an air knife 128 and a fluid outlet conduit 130 are provided for removing disinfected fluid 94 from the last roller member 102, as described above in relation to Figure 2. The removed fluid 94 is collected by the fluid outlet conduit 130.

Figure 6 shows fluid disinfection apparatus 140 according to a sixth embodiment of the invention. The apparatus 140 comprises a reservoir 142 for holding fluid 144 to be disinfected, first and second fluid dispersal means 146, 148 and first and second UV light sources 150, 152.

Each fluid dispersal means 146, 148 comprises a rotatably mounted stainless steel disc 154, a fluid outlet conduit 156 and a fluid outlet collar 158. The discs 154 are rotatably mounted on central spindles 160 and bearings 162 within fluid collection hoppers 164. The uppermost (as shown in the drawing) surfaces of the discs 154 are polished to an optically reflective finish.

The hoppers 164 are generally funnel shaped and have a fluid outlet 166 at the bottom (as shown in the drawing). The fluid outlet 166 of the first fluid dispersal means 146 is partly received within the fluid outlet conduit 156 of the second fluid dispersal means 148. The hoppers 164 are of a complimentary shape to the rotatably mounted discs 154 and are of larger diameter than the discs 154, so that the discs 154 can freely rotate within the hoppers 164.

The fluid outlet conduits 156 are coupled at one end to their respective discs 154. Primary fluid outlet apertures 168 are provided in the walls of the fluid outlet conduits 156 at their one ends. The fluid outlet conduits 156 are coupled at their other ends to drive belts 170 and pulleys (not shown).

The fluid outlet collars 158 are attached to the uppermost (as shown in the drawing) surfaces of the discs 154. The fluid outlet collars 158 are provided substantially co- axially with the fluid outlet conduits 156 and spaced from the fluid outlet conduits 156. The fluid outlet collars 158 extend part-way up the fluid outlet conduits 156. Secondary fluid outlet apertures 172 are provided in the collars 158.

A fluid delivery conduit 174 extends in fluid communication between the reservoir 142 and the fluid outlet conduit 156 of the first fluid dispersal means 146. A valve 176 is provided along the fluid delivery conduit 174 for controlling the flow of fluid 144 from the reservoir 142. Fluid 144 is delivered to the reservoir 142 via a fluid inlet 178. A maximum fluid level indicator 180 and a minimum fluid level indicator 182 are provided within the reservoir 142, via which the level of fluid 144 in the reservoir 142, and the flow of fluid into the reservoir, is controlled.

The UV light sources 150, 152 each comprise an array of six UV lamps 184 in the form of mercury arc discharge lamps. Each UV lamp 184 is tubular in shaped and is provided within a protective quartz sleeve 186. The UV lamps 184 are mounted on lighting assemblies 188, each UV lamp 184 being located within an elongate, part- cylindrical recess 190 the internal surface of which is optically reflective. The UV lamps 184 are positioned at a set distance from rotatably mounted discs 154 such that the UV light is of substantially uniform intensity across the surfaces of the discs 154.

In use, fluid 144 is delivered from the reservoir 142 through the fluid delivery conduit

174 to the fluid outlet conduit 156 of the first fluid dispersal means 146. The fluid 144 exits the fluid outlet conduit 156 via the primary outlet apertures 168 and is held between the fluid outlet conduit 156 and the fluid outlet collar 158. The fluid 144 exits the primary outlet apertures 168 at relatively high speeds and fluid outlet collar 158 serves to stop the fluid 144 hitting the surface of the rotatably mounted disc 154 at speed; which can result in the fluid 144 being deflected off the disc 154. The collected fluid 144 is subsequently delivered to the surface of the disc 154 at low speed via the secondary outlet apertures 172 in the collar 158.

Once delivered onto the surface of the rotating disc 154 the fluid 144 is dispersed into a film across the surface of the disc 154 by centrifugal forces existing due to the rotation of the disc 154. The surface of the disc 154, and thus the fluid film, is illuminated by UV light from the first array 150 of UV lamps 184. Continued rotation of the disc 154 causes the UV treated fluid 144 to be thrown off the edge of the disc 154 and into the hopper 164, where it is collected and mixed. The fluid 144 leaves the hopper 164 of the first fluid dispersal means 146 via the outlet 166 and is delivered into the fluid delivery conduit 156 of the second fluid dispersal means 148. The fluid 144 then undergoes a second stage of UV disinfection.

Figure 7 shows fluid disinfection apparatus 200 according to a seventh embodiment of the invention. The apparatus 200 is substantially the same as the apparatus 140 of the previous embodiment, with the following modifications.

In this embodiment the fluid disinfection apparatus 200 further comprises air dilution means 202 operable to deliver air bubbles 204 into the fluid 144 within the reservoir 142. The air dilution means 202 comprises a high pressure chamber 206, an air compressor 208 and an outlet nozzle 210.

A fluid inlet conduit 212 extends from the reservoir 142 to the high pressure chamber 206 and delivers a small amount of fluid 144a into the high pressure chamber 206 from the reservoir 142.

The air compressor 208 is operable to generate pressurised air, which is delivered through an air delivery conduit 214 into the fluid 144a within the high pressure chamber 206. The high pressure air is at least partially dissolved within the fluid 144a within the high pressure chamber 206. A fluid outlet conduit 216 delivers the fluid 144a containing at least partially dissolved air to the outlet nozzle 210. The outlet nozzle 210 is provided at the bottom of the reservoir 142. As the fluid 144a is released back into the reservoir 142, the pressure under which the fluid 144a is maintained is reduced back to atmospheric pressure, and the at least partially dissolved air forms into air bubbles 204 within the fluid 144 within the reservoir 142. The air bubbles 204 remain within the fluid 144 as it is dispersed into a fluid film on the surface of the rotatably mounted disc 154.

A fluid disinfection system 220 according to an eighth embodiment of the invention is shown in Figure 8. The fluid disinfection system 220 comprises a first fluid storage tank 222, a second fluid storage tank 224, and fluid disinfection apparatus 10 according to the first embodiment of the invention.

The fluid storage tanks 222, 224 are made of stainless steel and are each provided with a fluid inlet/outlet aperture 226, 228.

A first fluid conduit 230 extends between the inlet/outlet aperture 226 of the first storage tank 222 to one side of a first bi-directional valve 232. A second fluid conduit 234 extends between the other side of the first valve 232 and one side of a second bi-direction valve 236. A third fluid conduit 238 extends from the mid-point of the second fluid conduit 234 to the fluid inlet 22 of the fluid disinfection apparatus 10. A fourth fluid conduit 240 extends from the first fluid conduit 230 to one side of a third bi-directional valve 242. A fifth fluid conduit 244 extends from the other side of the third bi-directional valve 242 to one side of a fourth bi-direction valve 246. A sixth fluid conduit 248 extends from the other side of the fourth bi-directional valve 246 to the inlet/outlet aperture 228 of the second storage tank 224. A seventh fluid conduit 250 extends from the sixth fluid conduit 248 to the other side of the second bidirectional valve 236. An eighth fluid conduit 252 extends from the outlet conduit 38 of the fluid disinfection apparatus 10 to the fifth fluid conduit 244. A pump 254 and a one-way valve 256 are provided along the eighth fluid conduit 252 to pump disinfected fluid through the eighth fluid conduit 252 and to prevent the flow of fluid into the fluid disinfection apparatus 10 via the outlet conduit 38.

In operation, fluid 258 to be disinfected is delivered from the first storage tank 222 to the fluid disinfection apparatus via the first fluid conduit 230 to the first bi-directional valve 232. The first valve 232 is set open to allow fluid to pass through it to the second fluid conduit 234. The second valve 236 is closed, thereby routing fluid into the third fluid conduit 238 and thus into the fluid disinfection apparatus 10. Disinfected fluid leaves the fluid disinfection apparatus 10 through its outlet conduit 38, to the eighth fluid conduit 252. The disinfected fluid flows through the pump 254 and the one-way valve 256 to the fifth fluid conduit 244. The second valve 242 is closed, thereby routing disinfected fluid to the fourth valve, from where it flows through the sixth fluid conduit 248 to the inlet/outlet aperture 228 of the second storage tank 224. All of the fluid 258 is processed from the first storage tank 222 to the second storage tank 224 via the fluid disinfection apparatus 10.

The disinfected fluid 258 now stored in the second fluid storage tank 224 can then be re processed through the fluid disinfection apparatus 10 by closing the fourth valve 246 and the first valve 232, and opening the second valve 236 and the third valve 242. The fluid 258 is thereby routed from the second storage tank 224, through the sixth fluid conduit 248, the seventh fluid conduit 250, the second fluid conduit 234 and the third fluid conduit 238, to the fluid disinfection apparatus 10, and from the fluid outlet 38 of the fluid disinfection apparatus 10, through the eighth fluid conduit 252, the fifth fluid conduit 244, the fourth fluid conduit 240 and the first fluid conduit 230 to the first fluid storage tank 222.

The fluid 258 can undergo multiple passes through the fluid disinfection system 220 by opening and closing the valves as described above.

Figure 9 shows fluid disinfection apparatus 260 according to a ninth embodiment of the invention. The apparatus 260 of this embodiment is substantially the same as the apparatus 10 of the first embodiment 10, with the following modifications. The same reference numbers are retained for corresponding features.

In this embodiment, the apparatus 260 further comprises film thickness control means in the form of a generally hemi-cylindrical, quartz film thickness control member 262. The film thickness control member 262 is of a complimentary size and shape to the part of the roller member 14 received within it. The film thickness control member 262 is provided adjacent to the roller member 14 and is spaced from the surface 14a of the roller member 14 by a distance equal to the desired maximum thickness of the film 264 of fluid 20. In addition to controlling the thickness of the fluid film 264, the film thickness control member 262 causes the fluid within the film 264 to mix as the roller member 14 rotates past the film thickness control member.

Because the film thickness control member 262 is made of quartz, which is transparent to ultra-violet light, the film thickness control member 262 can be provided between the roller member 14 and the array of UV lamps 16. The film thickness control member 262 can therefore additionally act to protect the UV lamps 16 from fluid spray; although in this example the UV lamps 16 are shown covered by quartz sleeves 40 it will be appreciated that these may be removed.

Various modifications can be made to the described embodiments without departing from the scope of the invention. For example, the fluid dispersal means may disperse the fluid into a fog or spray which is then irradiated with UV light. Any of the described rotatably mounted surfaces may be polished to an optically reflective finish or may have an optically reflective and/or photo catalytic oxidizing coating provided thereon. The described rotatably mounted surfaces may alternatively or additionally be patterned or roughened in order to improve the adhesion of low viscosity fluids thereon.

The described roller members may alternatively be solid, and may be of a different length and/or circumference to those described. The roller members may also rotate at a different speed to that described, thereby processing a different volume of fluid to that described. Where the roller member is described as being porous, it will be appreciated that a different porous material may be used. Where a solid wiper is described it will be appreciated that an air knife may alternatively be used.

A different number of UV lamps may be provided within each UV light source to those described, and the UV lamps may be provided in a different configuration to those shown in the drawings. The UV lamps may comprise a different type of UV lamp to those described, and the UV lamps may be provided within a different type of protective sleeve.

Where the apparatus comprises a plurality of roller members it will be appreciated that a different number of roller members may be used to that described. Where the rotatably mounted surface is described as a rotatably mounted disc it will be appreciated that does not need to be limited to being circular in shape. The surface of the disc may be provided with one or more substantially concentric rings which acts as mini weirs, causing fluid dispersing across the surface of the disc to mix as it encounters and flows over each ring. A UV transparent film thickness control member may be provided over the or each rotatably mounted disc, between the disc and the array of UV lamps. It will also be appreciated that a different number of fluid dispersal means may be provided to that described.

Regarding the fluid disinfection system it will be understood that any of the described fluid disinfection apparatus may be used in place of the fluid disinfection apparatus of the first embodiment. It will also be appreciated that a different arrangement of fluid conduits and valves may be provided to define fluid flow paths between the storage tanks via the fluid disinfection apparatus.

The described embodiments provide various advantages, as follows. The fluid disinfection apparatus can effectively disinfect low transmissivity fluids, such as fruit juices and syrups, at ambient room temperature. Since the fluid is not heated, the flavour of the fluid is not affected buy the disinfection process. The fluid disinfection apparatus has relatively low power consumption due to the relatively low optical power required for the UV lamps as a result of the fluid being dispersed into a film prior to irradiation. The fluid disinfection apparatus can disinfect fluids at a relative high processing rate. The effectiveness of the disinfection is further improved by the provision of a photo catalytic oxidizing coating on the rotatably mounted surface across which the fluid is formed into a film.

Claims

1. Fluid disinfection apparatus comprising: a reservoir for holding a fluid to be disinfected; fluid dispersal means operable to remove fluid from the reservoir and disperse the removed fluid; and an ultra violet light source operable to irradiate at least part of the film of fluid with ultra violet light.

2. Apparatus as claimed in claim 1 , wherein the fluid dispersal means is operable to disperse the removed fluid into a film of fluid.

3. Apparatus as claimed in claims 1 or 2, wherein the fluid dispersal means comprises a rotatably mounted surface in fluid communication with the reservoir, rotation of the surface causing the removed fluid to be dispersed into a film across the surface.

4. Apparatus as claimed in claim 3, wherein the rotatably mounted surface comprises the surface of a substantially cylindrical roller member.

5. Apparatus as claimed in claim 4, wherein the roller member is rotatably mounted on a centrally located drive shaft coupled to drive means operable to cause rotation of the rotatably mounted surface at a desired speed.

6. Apparatus as claimed in claims 4 or 5, wherein the roller member is partly received within the reservoir, such that, when fluid is present within the reservoir, the roller member is partly submerged in the fluid.

7. Apparatus as claimed in claim 6, wherein the roller member is additionally movably mounted such that the amount of the roller member received within the reservoir may be varied.

8. Apparatus as claimed in any of claims 4 to 7, wherein the reservoir comprises a storage part and a sump part, in fluid communication with the storage part, within which the roller member is partly received, rotation of the roller member within the sump part causing fluid to adhere to the surface of the roller member and be dispersed into a film across the surface of the roller member.

9. Apparatus as claimed in claim 8, wherein the sump part is of a complimentary size and shape to the part of the roller member to be received within it.

10. Apparatus as claimed in any of claims 4 to 9, wherein the fluid dispersal means further comprises film thickness control means.

11 . Apparatus as claimed in claim 10, wherein the film thickness control means comprises wiper means provided above the fluid level of the reservoir at a rotational position close to the point at which the surface of the roller member emerges from the fluid within the reservoir, and at a distance from the surface of the roller member equal to a desired film thickness, such that as the roller member emerges from the reservoir any surplus fluid adhering to its surface is wiped off by the first wiper means, thereby ensuring that the fluid film is of a desired thickness.

12. Apparatus as claimed in claim 10, wherein the film thickness control means comprises a part-cylindrical film thickness control member provided adjacent to and spaced from the roller member, the film thickness control member being of a complimentary size and shape to the roller member, and the separation between the film thickness control member and the roller member defining the thickness of the fluid film on the surface of the roller member.

13. Apparatus as claimed in claim 12, wherein the film thickness control member extends around substantially all of the part of the roller member not received within the reservoir.

14. Apparatus as claimed in claims 12 or 13, wherein the film thickness control member is provided between the roller member and the ultra violet light source and is made of an ultra-violet transparent material.

15. Apparatus as claimed in any of claims 10 to 14, wherein the fluid disinfection apparatus further comprises fluid collection means comprising wiper means acting against the surface of the roller member and a fluid outlet conduit into which fluid wiped off the roller member is delivered by the second wiper means, the second wiper means being provided above the fluid level of the reservoir at a rotational position close to the point at which the surface of the roller member enters the fluid within the reservoir.

16. Apparatus as claimed in any of claims 10 or 15, wherein the or each wiper means comprises a solid blade or an air knife.

17. Apparatus as claimed in claim 3, wherein the rotatably mounted surface comprises the surface of a rotatably mounted plate.

18. Apparatus as claimed in claim 17, wherein one or more generally annularly shaped weir members are provided on the surface of the rotatably mounted plate, to promote mixing of the fluid as it disperses across the surface of the plate.

19. Apparatus as claimed in claim 18, wherein the fluid dispersal means further comprises fluid delivery apparatus extending in fluid communication between the reservoir and the rotatably mounted plate.

20. Apparatus as claimed in claim 19, wherein the fluid delivery apparatus comprises a fluid outlet conduit connected at one end to the rotatably mounted surface and coupled to drive means operable to cause rotation of the rotatably mounted surface at a desired speed, and a fluid delivery conduit in fluid communication between the reservoir and the fluid outlet conduit, the fluid outlet conduit having a plurality of fluid outlet apertures provided towards its one end through which fluid is delivered to the surface of the rotatably mounted surface.

21 . Apparatus as claimed in claim 20, wherein the fluid delivery apparatus further comprises a collar member provided on the rotatably mounted surface, the collar member extending around and being spaced from the fluid outlet conduit, and the collar member having a plurality of secondary fluid outlet apertures provided therein, such that fluid exiting the fluid outlet conduit is caught by the collar member and then delivered to the rotatably mounted surface via the secondary fluid apertures.

22. Apparatus as claimed in any of claims 17 to 21 , wherein the fluid dispersal means further comprise film thickness control means comprising a film thickness control member provided adjacent to and spaced from the rotatably mounted plate, the film thickness control member being an annular plate of a complimentary size and shape to the rotatably mounted plate, and the separation between the film thickness control member and the rotatably mounted plate defining the thickness of the fluid film on the surface of the rotatably mounted plate.

23. Apparatus as claimed in claim 22, wherein the film thickness control member is provided between the rotatably mounted plate and the ultra violet light source and is made of an ultra-violet transparent material.

24. Apparatus as claimed in any of claims 17 to 23, wherein the fluid disinfection apparatus further comprises fluid collection means comprising a hopper member within which the rotatably mounted plate is provided, the hopper member having a greater diameter than the rotatably mounted plate, such that fluid leaving the edge of the rotatably mounted plate is collected within the hopper member, and being generally funnel shaped, including a fluid outlet conduit.

25. Apparatus as claimed in claim 24, wherein the fluid disinfection apparatus comprises a plurality of rotatably mounted plates, fluid delivery apparatus and fluid collection means, a first fluid outlet conduit being provided in fluid communication with the fluid delivery conduit of a subsequent fluid delivery apparatus.

26. Apparatus as claimed in claim 1 , wherein the fluid dispersal means comprises a plurality of roller members arranged in fluid communication in a spaced series; the first roller member of the series being in fluid communication with the reservoir and rotation of the first roller member causing fluid to be removed from the reservoir and dispersed into a film across the surface of the first roller member; and rotation of a subsequent roller member of the series causing the fluid to be removed from the previous roller member of the series and dispersed into a film across the surface of the subsequent roller member.

27. Apparatus as claimed in claim 26, wherein adjacent roller members within the series rotate in opposite senses, such that as fluid is transferred from one roller member to the subsequent roller member the fluid undergoes mixing.

28. Apparatus as claimed in claims 26 or 27, wherein the fluid disinfection apparatus further comprises fluid collection means comprising wiper means acting against the surface of the final roller member within the series and a fluid outlet conduit into which fluid wiped off the roller member is delivered by the wiper means.

29. Apparatus as claimed in claim 28, wherein the wiper means comprise a solid blade or an air knife.

30. Apparatus as claimed in any preceding claim, wherein the or each rotatably mounted surface is an optically reflective surface.

31 . Apparatus as claimed in claim 30, wherein the or each rotatably mounted surface is a polished surface or is provided with an optically reflective coating.

32. Apparatus as claimed in claims 30 or 31 , wherein the or each rotatably mounted surface is provided with a photo-catalytic oxidizing coating.

33. Apparatus as claimed in claim 32, wherein the coating is of anataise titanium dioxide.

34. Apparatus as claimed in any preceding claim, wherein the or each rotatably mounted surface is patterned or roughened in order to improve the adhesion of low viscosity fluids thereon.

35. Apparatus as claimed in any preceding claim, wherein the or each rotatably mounted surface is porous, such that air may be delivered through the porous surface to form air bubbles within a film of fluid present on the surface, to thereby increase the transmissivity of the fluid.

36. Apparatus as claimed in any preceding claim, wherein the fluid disinfection apparatus comprises air dilution means operable to deliver air bubbles into the fluid within the reservoir.

37. Apparatus as claimed in claim 36, wherein the air dilution means comprises a high pressure chamber into which part of the fluid within the reservoir is delivered, an air compressor operable to deliver pressurised air into the fluid within the high pressure chamber, the air being at least partially dissolved within the fluid, and a delivery nozzle through which the fluid containing at least partially dissolved air is released back into the reservoir, the at least partially dissolved air thereby forming into air bubbles within the fluid.

38. Apparatus as claimed in any preceding claim, wherein the ultra violet light includes one or more wavelengths within the range 220 to 280 nanometres, being germicidal ultra violet wavelengths.

39. Apparatus as claimed in claim 38, wherein the ultra violet light source comprises one or more ultra violet lamps.

40. Apparatus as claimed in claim 38, wherein the or each ultra violet lamp is located substantially adjacent its respective rotatably mounted surface, such that output of the or each lamp illuminates the surface.

41 . Apparatus as claimed in claims 39 or 40, wherein the or each ultra violet lamp is mounted within a movably mounted lighting assembly, the lighting assembly being of an ultra violet non-transmitting material to ensure that all of the ultra violet light is retained within the fluid disinfecting apparatus.

42. A fluid disinfection system comprising: a first fluid storage tank having a first fluid inlet/outlet aperture; a second fluid storage tank having a second fluid inlet/outlet aperture; fluid disinfection apparatus according to any preceding claim; a first fluid flow path extending from the first fluid inlet/outlet aperture to the fluid disinfection apparatus reservoir fluid inlet; a second fluid flow path extending from the fluid disinfection apparatus collection means outlet to the second fluid inlet/outlet aperture; a third fluid flow path extending from the second fluid inlet/outlet aperture to the fluid disinfection apparatus reservoir fluid inlet; and a fourth fluid flow path extending from the fluid disinfection apparatus collection means outlet to the first fluid inlet/outlet aperture, such that fluid may be transferred from the first fluid storage tank to the second fluid storage tank via the fluid disinfection apparatus, and vice versa, thereby enabling fluid to undergo multiple passes through the fluid disinfection apparatus.

43. A method of disinfecting a fluid, the method comprising: dispersing the fluid; and irradiating at least part of the dispersed fluid with ultraviolet light.

44. A method as claimed in claim 43, wherein the fluid is dispersed into a film of fluid.

45. A method as claimed in claim 44, wherein the method further comprises introducing air bubbles into the fluid to increase the transmissivity of the fluid.

46. Fluid disinfection apparatus substantially as described above with reference to the accompanying drawings.

47. A fluid disinfection system substantially as described above with reference to the accompanying drawings.