FLUID TREATMENT

Abstract: Apparatus for sterilising fluid comprising an ozone chamber (10) in which ozone is generated. The ozone is evenly dispersed throughout the ozone/air mixture by a diffuser (13). The fluid and ozone mixture are thoroughly mixed in a chamber (18) and radiated with ultraviolet radiation which simultaneously releases atomic oxygen from the ozone and radiates the fluid to be treated.

Description: FLUID TREATMENT The invention relates to treatment of fluids. The invention relates more particularly although not exclusively to sterilising fluids. Fluids which are usually defined as gases or liquids include for the purpose of this invention also slurries, homogeneous mixtures, such as soups, as well as effluent and the like. The methods and apparatuses of the inventions are capable of treating any mixture or material which can flow or be generally pumped through a chamber for treatment. The applications of current interest are food and beverage processing plants, water bottling plants, swimming pools, fish farming, aquariums, secondary effluent treatment or generally any polluted or foul smelling water or air. According to one aspect of the invention there is provided a method of treating fluids comprising thoroughly mixing the fluid with ozone in a chamber and subjecting the mixture to ultraviolet radiation to break down the ozone so that the fluid is simultaneously treated by oxygen atoms released by the radiation and by the radiation itself. The ozone may be mixed with a separate fluid in a diffuser and thorough mixing of the fluid with the fluid to be treated achieved by supplying the diffused ozone directly into the chamber. The separate fluids are preferably air or oxygen. According to another aspect of the invention there is provided an apparatus for treating fluids comprising an ozone chamber in which ozone is produced from air, a diffuser through which the ozone/air mixture is fed to an ultraviolet chamber so as to be thoroughly mixed with the fluid to be treated and exposed to ultraviolet radiation to simultaneously radiate the fluid and break down the ozone. The diffuser may include a micro-diffuser element to evenly disperse the ozone throughout the air mixture and the diffuser may be attached to one side of the ultraviolet chamber adjacent an input end at which the fluid to be treated is supplied to the ultraviolet chamber. An outlet may be provided between the ozone chamber and the ultraviolet chamber to release the ozone for use in another apparatus- Fluid treatment apparatuses according to the invention will now be described by way of example with reference to the accompanying drawings in which: - Figure 1 is a front schematic view of one apparatus; Figure 2 is a sectional enlarged view of a micro diffuser for use in the apparatus. Figure 3 is a schematic plan view of another apparatus; Figure 4 is a schematic elevation of the other apparatus; Figure 5 is a schematic side view of the other apparatus; and Figure 6 is an enlarged view of a diffuser for use in the other apparatus. Referring to the Figure 1, a generally conventional ozone chamber 10 is connected to a supply of compressed air and includes an ozone lamp (not shown), for example, a mercury lamp having an output generally about 1850 A. The lamp output converts oxygen in the air in the chamber 10 to ozone. An outlet 11 of the chamber 10 is connected to supply the ozone/air mixture to either a valved outlet 12, to release the mixture to atmosphere or for use in other treatment apparatus, or to a diffuser 13, shown in more detail in Figure 2. A water reservoir 14 and a drain 15 are provided for collecting and removing accumulated condensed water vapour from time to time. The diffuser 13 includes a porous inert micro-diffuser element 16 to the top of which the ozone/air mixture is supplied under pressure to disperse the ozone evenly throughout the air mixture as it is released into the ultraviolet chamber 18. The fluid to be treated is supplied and pumped into the apparatus via an inlet 17 into an ultraviolet chamber 18. The release of the ozone mixture into the ultraviolet chamber 18 via the diffuser causes thorough mixing of the ozone with the fluid to be treated. The chamber 18 includes a mercury vapour lamp (not shown) which radiates the fluid and ozone mixture in the chamber with ultraviolet light as it passes to an apparatus outlet 19. The fluid discharged from the outlet 19 is fully treated and contains no ozone. The ozone/air mixture may be mixed with an additional separate fluid, as described later, as or before the ozone enters the diffuser. The method of treating fluids and the apparatus described comprises in its simplest form a simultaneous ozone and ultraviolet treatment. Ozone is already known for treating, and especially sterilising, fluids. Likewise, sterilisation processes which use ultraviolet radiation are already currently practised- It has not however been proposed before to apply ultraviolet radiation to a fluid to be treated which has been mixed, and in this embodiment thoroughly mixed, with ozone. Thus, the ultraviolet radiation is applied to an "ozone rich" fluid resulting in practice to an overall much more and surprisingly effective treating process. Typical and satisfactory apparatuses have fluid through-flow rates of between about 80 and 500 litres per minute. The ozone generated and used amounts to about 15 grams per hour and the total electric power consumption (for forming the ozone and creating the ultraviolet radiation) Is between about 500 and 800 watts, respectively for the two flow rates- An advantage of embodiments of the invention is that ozone is broken down by the ultraviolet radiation. The method can be readily arranged so that any ozone remaining in the mixture is always broken down in the chamber 18. In processes where ozone is used alone, especial care Is required to prevent ozone that Is not used (i-e- broken down) into oxygen or oxides, in the sterilising or treating, is removed or kept free of the fluid after treatment. This has meant that ozone treatment of food products or other fluid that returns for use to a system (e.g. fish tank water) is not always possible and certainly must be carefully controlled. If not, 'unused' ozone can have a detrimental effect by attacking and often damaging healthy organisms and plants. Thus, generally only low dosages of ozone have been used in practice in the past or a special added step is required in the process to remove any unused ozone. While the above paragraph discusses typical apparatus, it should be realised that this invention is equally applicable to smaller and larger units, for example, units with a fluid through flow rate in excess of 10,000 litres per minute. The corresponding increase in ozone consumption may be in the order of 200 - 300 grams per hour. The actual ozone and ultraviolet radiation usage would depend on the application. The apparatus shown in Figures 3 to 6, comprises two ozone chambers 20 and 21 and two ultraviolet chambers 22 and 23. Each chamber is provided with two or more elongate lamps (not shown) extending along their lengths in sealed enclosures within the chambers to radiate the insides of the chambers with ultraviolet radiation in a manner well known per se. The chambers 20 and 21 receive a supply of air from which, in use, the ozone is formed. The air also carries the ozone to chambers 22 and 23 as discussed in more detail below. The chambers 22 and 23 are connected in parallel by tubes to receive at inlet ends fluid to be treated and at their outlet ends to allow the treated fluid to flow away. Other generally conventional components shown in the Figures do not form direct parts of the present invention. Diffusers 24 having micro-diffuser elements 25 incorporating ceramic particles or fibres are fitted to the sides of the chambers 22 and 23 adjacent their inlet ends and air is supplied together with the ozone from the chambers 20 and 21 into the diffusers. Ozone entering the chambers is therefore effectively dispersed or diffused to spread out and so as to thoroughly mix with the fluid to be treated in the chambers 22 and 23. As the ozone is dispersed into the fluid to be treated and flows along the chambers 22 and 23, from the inlet ends to the outlet ends, the ultraviolet radiation not only acts on an . Impurities or organic matter in the fluid but also releases atomic oxygen by breaking down the ozone molecules. This breaking down of ozone under the action of radiation while it is thoroughly mixed with the fluid to be treated provides that the fluid is simultaneously acted upon directly by the ultraviolet radiation and also the released oxygen atoms. The radiation in the ultraviolet chambers 22 and 23 preferably has a wavelength of 2537 A and it has been found that if the simultaneous activity Is carried out as described with the oxygen atoms being released as a result of the radiation, the treating time can be reduced to a few minutes whereas if the same effective treatment is carried out In two stages using ozone and ultraviolet radiation separately, the time required for the same results is several times, say ten times, longer. It has been mentioned earlier, in respect of the apparatus of Figures 1 and 2, that the ultraviolet radiation also has the effect of ensuring that the treated fluid leaving the exit ends of the chambers 22 and 23 is completely free of ozone. This depends of course on ensuring that the relative quantity of ozone supplied into th chambers is below a certain percentage of the overall mixture in th chambers and also on the contamination level of the fluid to b treated. It is quite possible in any event to ensure, by increasin the relative supply of ozone, that some ozone remains in the treate fluid passing through the outlets of the chambers 22 and 23. This ca be beneficial in a closed system, or where the outlet fluid does no have to be free of ozone for other reasons, because the ozone will then continue to break down, albeit relatively slowly, and sterilise other parts of the closed system. Thus, the described apparatus may be arranged to provide treated fluid containing a chosen percentage of unreacted ozone to continue to further sterilise or treat the fluid and/or surfaces of pipes and other components which the treated fluid contacts after leaving the ultraviolet chambers 22 and 23. For normal operation, the ozone is mixed in the diffusers with air but other fluids may be used including water. For more difficult applications, that is, when the fluid to be treated is very contaminated or a higher flow rate is required, oxygen may be mixed with the ozone in the diffusers. Also, it will be appreciated that additionally or alternatively, the treated fluid may be re-cycled so as to pass through the ultraviolet chambers twice or several times as may be required. Bad smelling air or other forms of polluted air may be treated in the same manner as described above.

Claims: CLAIMS 1. A method of treating fluids comprising thoroughly mixing th fluid with ozone in a chamber and subjecting the mixture t ultraviolet radiation to break down the ozone so that the fluid i simultaneously treated by oxygen atoms released by the radiation an by the radiation itself. 2. A method according to claim 1, including mixing the ozone wit a separate fluid in a diffuser and thoroughly mixing the fluid wit the fluid to be treated by supplying the diffused ozone directly Inte the chamber. 3. A method according to claim 2, In which the separate fluid is oxygen. 4. A method according to claim 2, in which the separate fluid is air. 5. Apparatus for treating fluids comprising an ozone chamber in which ozone is produced from air, a diffuser through which the ozone/air mixture is fed to an ultraviolet chamber so as to be thoroughly mixed with the fluid to be treated and exposed to ultraviolet radiation to simultaneously radiate the fluid and break down the ozone. 6. Apparatus according to claim 5, in which the diffuser includes a micro-diffuser element to evenly disperse the ozone throughout the air mixture, and the diffuser is attached to one side of the chamber adjacent an input end at which the fluid to be treated is supplied to the chamber. 7. Apparatus according to claim 5 or 6, in which an outlet is 5 provided between the ozone chamber and the ultraviolet chamber to release the ozone for use in another apparatus. 8. Methods of treating fluids substantially as herein described with reference to the accompanying drawings. 9. Apparatus for treating fluids substantially as herein described 10 with reference to the accompanying drawings. t

Inventors: MORTENSEN JORGEN GUDIK, MORTENSEN, JORGEN, GUDIK
Applicants: MORTENSEN & CO LTD J, J. MORTENSEN & CO., LTD.
Application year: 1992
Main classification: A61L9
IPC codes: A61L2, A61L9, C02F1