GB2355980A

GB2355980A - Water purification

Info

Publication number: GB2355980A
Application number: GB9926200A
Authority: GB
Inventors: Dr Sekhar Deb
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-11-06
Filing date: 1999-11-06
Publication date: 2001-05-09
Also published as: GB9926200D0

Abstract

A low cost system of water purification, which lends itself to portable use e.g. in the home, comprises an ozone source 11 in association with a vessel 13 containing a filter means 16. Ozone passes through water in the vessel, removing bacteria, viruses, fungi and small solid particles; the water then passes through the filter means that may be in the form of ceramic candle filters. The ozone generator 11 may be of the corona discharge type. The ozone may be delivered to the water via a ceramic diffuser stone 12.

Description

2355980 1 WATER PURIFICATION 2 The invention relates to a system of water

purification which lends itself to portable small scale domestic use.

In many parts of the world water supplies are of poor quality, often containing bacteria, viruses, fungi and particles of metal or metal salts such as iron,, lead and arsenic. Domestic water filters are widely available, comprising of a vessel containing a filtering means such as solid porous ceramic filters. Water passes through the filtering means which removes the larger solid particles but not smaller solid particles and bacteria, viruses or fungi. Thus although this is a relatively cheap filtration method it is not very efficient. Another way of purifying water is to use ultra violet light but such systems are expensive and whilst they kill a substantial proportion of bacteria, cannot remove solid metal particles.

An object of this invention is to provide a purification system which is effective against bacteria, viruses, fungi and metals/metal salts but relatively cheap to buy and maintain for the consumer market.

According to one aspect of the present invention a purification system for water comprises an ozone source in association with a vessel containing a filtering means.

According to a further aspect of the present invention a method of purifying a water comprises the steps of passing ozone through the water and passing the water through a filtering means contained within a vessel.

3 Ozone is an excellent oxidising agent which kills bacteria, viruses and fungi and converts soluble metal salts into insoluble metal salts which can be caught by filtering means. Ozone generators are readily available, easy to use and relatively cheap to buy and run.

Ozone is unstable and therefore cannot be stored in cylinders. The ozone source is preferably an ozone generator consisting of apparatus which passes electric current through air or oxygen, resulting in ozone. These are known in the art and readily available. The volume of ozone required will depend upon the volume of water to be purified. The flow rate of ozone will determine the speed of water purification. These parameters can be readily determined by those skilled in the art.

The vessel containing the filtering means is preferably of stainless steel and components such as connecting pipes for transporting ozone should be made of food grade materials. Typically the volume of the vessel would be in the range 10 to 5 0 litres.

The filtering means is preferably solid porous ceramic or carbon for efficiency and low cost. Alternatively a silver impregnated carbon filter can be used although this is more costly. The filtering means may take many forms but may conveniently be a candle shape.

Where the ozone enters the vessel it is preferably passed through a diffuser such as a ceramic stone. Preferably the ozone source is positioned above the water level to minimise syphoning problems.

4 If desired a catalyst for oxidation of metal salts by ozone can be introduced into the vessel; an example of a catalyst would be a calcium salt. A catalyst will not usually be necessary if iron salts are present in the water because these would act as a catalyst.

The ozone can be introduced into the water either before or after it has passed through the filtering means. Where metal salts are dissolved in the water it is preferable for the ozone to be passed through it before the filtering means. In this way, the ozone oxidises the metal salt which precipitates out and can be caught by the filtering means.

Preferably, the vessel is provided with an outlet to allow exhaustion of gases.

The usual means for dispensing purified water from the vessel would be a tap fitted at or near the base of the vessel. To prevent impurities entering the vessel a lid would normally be fitted on top. Removal of the lid is necessary to add water to be purified.

A preferred embodiment of the invention will now be described with reference to the accompanying drawing in which; Figure I is a cross-sectional view of a portable water purification system suitable for domestic use consisting of an air pump, ozone generator and vessel containing filtering means.

As shown in Figure 1, an air pump 10 is connected by pipe to an ozone generator I I of the type in which corona discharge is used to convert oxygen in the air to ozone. The ozone generator I I is connected by pipe to a ceramic diff-user stone 12 at the bottom of a vessel 13. The vessel 13 is a stainless steel cylinder with a removable lid 14 and is divided into two chambers by a wall 15 provided with two apertures into which ceramic candle filters 16 are fitted. A gas outlet 17 is provided just below the wall 15. An outlet tap 18 is fitted just above the base of the vessel 13.

In use for water purification, dirty/contaminated water 19 is poured into the upper chamber of the vessel 13 and the lid 14 is fitted on the top. Water 19 passes through the filters 16 and enters the lower chamber as droplets 20, collecting in the bottom of the vessel 13. Solid particles in the water 19 are trapped in the filters 16. Electrical power is provided to the air pump 10 which pushes air through the ozone generator 11. Electrical power supplied to the ozone generator I I converts air into ozone. The ozone then passes through a pipe into the vessel 13 by way of the ceramic diffuser stone 12. Ozone diffuses through the filtered water in the lower chamber of the vessel 13, killing bacteria, viruses and ftingi by oxidation. Excess gases are expelled through the gas outlet 17. When purified water is required, having allowed sufficient time for the -excess ozone gas to be expelled, the outlet tap 18 is turned on.

In a modification of the system shown in Figure 1, the ozone is introduced through the diffuser stone 12 positioned in the upper chamber of the vessel. As before, ozone kills bacteria, viruses and ftingi by oxidation. In addition ozone oxidises metal salts dissolved in the water causing them to 6 precipitate out. These salt particles are then caught by the filters 16. If necessary a catalyst can be introduced into the upper chamber, for reasons already explained.

7 P. 1003

Claims

I. A purification system for water comprises an ozone source in association with a vessel containing a filtering means.
2. A purification system according to Claim 1, in which the ozone source comprises an ozone generator.
3. A purification system according to Claim 2, in which the ozone generator relies on high voltage discharge.
4. A purification system according to any preceding claim, in which the filtering means comprises a solid porous material.
5. A purification system according to Claim 4, in which the filtering means comprises at least one ceramic candle filter.
6. A purification system according to any preceding claim, in which the vessel comprises a closed cylinder.
7. A purification system according to any preceding claim, in which the vessel has a capacity of from 10 to 50 litres.

8. A purification system according to any preceding claim, which is portable.
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9. A purification system according to any preceding claim, in which a diff-user is provided in the vessel which is connected to the ozone source.
10. A purification system according to any preceding claim, in which the ozone source is positioned in relation to the vessel in such a way that ozone would pass through the water before the water passed through the filtering means.
11. A purification system according to any one of Claims I to 9, in which the ozone source is positioned in relation to the vessel in such a way that the water would pass through the filtering means before ozone passes through the water.
12. A purification system according to any preceding claim in which the vessel is provided with a gas outlet.
13. A purification system according to any preceding claim, in which the vessel is provided with an outlet tap.
14. A purification system according to any preceding claim, which is for domestic use.
15. A purification system according to Claim 1, substantially as hereinbefore described.
16. A purification system according to Claim 1, substantially as hereinbefore described with reference to the accompanying drawing.

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17. A method of purifying a water comprising the steps of passing ozone through the water and passing the water through a filtering means contained within a vessel.
A method according to Claim 17, having the feature of any one of Claims I to 16.
19. A method according to Claim 17 or 18, in which a catalyst for oxidation of a component of the water by the ozone is introduced into the vessel.
20. A method according to Claim 17, substantially as hereinbefore described with reference to the accompanying drawing.

EAF/AMM