WO2006130052A1

WO2006130052A1 - Method and device for purification of water

Info

Publication number: WO2006130052A1
Application number: PCT/SE2005/000817
Authority: WO
Inventors: Lennart Olausson
Original assignee: Lennart Olausson
Priority date: 2005-05-30
Filing date: 2005-05-30
Publication date: 2006-12-07
Also published as: SE0702363L; NO20076686L

Abstract

The invention relates to a method and an arrangement for treatment of water in an establishment in which water is circulated in a cycle. The method may particularly be used in purification of bathwater in a bath establishment. Water is lead from a pool (2), via a conduit (9) and through a filter (3a, 3b, 3c). Thereafter, the water is returned to the pool 2. Hydrogen peroxide is supplied in order to disinfect the water. The filter or filters contain(s) small soda lime glass balls.

Description

Method and device for purification of water

TECHNICAL FIELD The present invention relates to a method and an arrangement for purification of water, such as purification of bathwater in a bathing in a baths establishment.

BACKGROUND OF THE INVENTION

Filters and chemicals are sometimes used for purification of water in a baths establishment e.g., in order to meet hygienic requirements. Various solid contaminants are caught by the filter in order to subsequently be removed. Often, the chemicals used for disinfection are chlorine-containing chemicals. The used filters are mostly sand filters of a certain bed height. As chlorine-containing chemicals for the purification of the bathwater cause troubles both to bathers and employees at baths establishments, there has been a strive to avoid the use of chlorine. An alternative to chlorine-containing chemicals is to use hydrogen peroxide (H₂O₂) as a chemical added for disinfection of the bathwater. This chemical is considered by the bathers and the employees to be very positive, i.e. it does not have the disadvantages of the chlorine-containing chemicals. The hydrogen peroxide is less aggressive.

Experience has shown however that hydrogen peroxide is a chemical product that is less stable and that tends to be decomposed. Additional hydrogen peroxide must then be supplied to maintain an appropriate level of hydrogen peroxide in the bathwater. Since hydrogen peroxide is costly, it is desirable to keep the hydrogen peroxide consumption as low as possible.

It has previously been suggested in WO 2004/085026 that hydrogen peroxide could be used for purification of water in a baths establishment. The document discloses how the water in the baths establishment is circulated from a pool, via a number of filters and then back to the pool. It is further stated that hydrogen peroxide is added to water having passed through the filters. It is also stated that the filters are sand filters.

The object of the present invention is to provide a method and an arrangement for purification of water such as bathwater in a baths establishment, in which hydrogen peroxide is used to disinfect the water. The present invention aims in that connection to reduce the consumption of hydrogen peroxide. BRIEF ACCOUNT OF THE INVENTION

The invention relates to a method and an arrangement for treatment of water in an establishment in which water is circulated in a cycle. In particular, the method may relate to treatment of water in a baths establishment but can also be used to treat water in other establishments in which water should be disinfected. When the method according to the invention is applied on a baths establishment, water is led from a pool in the baths establishment and is circulated in a cycle via at least one filter in order to subsequently be returned to the pool, whereby hydrogen peroxide is added to the water in the baths establishment. The filter comprises a layer of glass particles, preferably soda lime glass. The glass particles may have a diameter of 0.42-0.84 mm.

A suitable chemical composition for the glass particles may be, in % by weight: SiO₂ 68 - 73

Na₂O + K₂O 13 - 15 CaO 8 - 11

MgO 3 - 5

Al₂O₃ 0.5 - 2

The glass particle layer in the filter is preferably at least 600 mm in thickness and most preferably at least 700 mm in thickness.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 schematically shows a baths establishment.

Fig. 2 shows a part of the baths establishment shown in Fig. 1. Fig. 3 shows, schematically and in cross-section, a filter intended to be used in a baths establishment.

DETAILED DESCRIPTION OF THE INVENTION

Referring to Fig. 1 there is shown a baths establishment 1 that comprises a pool 2. Contamination of the bathwater inevitably occurs when visitors in the baths establishment bathe in the pool 2. In order to purify the bathwater, water is led from the pool 2 via a conduit 9, in order to be led to at least one filter 3. It is shown in Fig. 1 and Fig. 2 how water is led through three filters 3a, 3b, 3c. It should be realised that other possibilities are conceivable, such as one filter, two filters, four filters or more than four filters. The figures show that the filters are connected in parallel, to each other. It should be realised however that other options can be considered. Fig. 1 shows that a pump 8 is connected to the conduit 9 in order to pump the water in the conduit. It should be realised that the placement of the pump could be different than that shown in Fig. 1. It should also be realised that the establishment may comprise a plurality of pumps. Fig. 1 shows that water that passes through the conduit 9 may pass via an equalizing tank 7 before the water is led on to the filters 3a, 3b, 3c. Fig. 1 shows that the conduit 9 that leads water away from the pool 2 branches in three conduits 10a, 10b and 10c, that each lead to one filter 3 a, 3b and 3c, respectively. After having passed the filter or filters 3 a, 3b, 3c, the water continues in a conduit 11 that leads the water back to the pool 2. Fig. 1 shows that the return conduit 11 braches in a point 12 in which a separate conduit 13 lets a portion of the flow of water pass a supply point 17 for supply of hydrogen peroxide from a container 15 for hydrogen peroxide. From the hydrogen peroxide (or a solution containing hydrogen peroxide) container 15, via a conduit 16 and to the supply point 17 in which hydrogen peroxide is mixed into the water. The conduit 13 that takes up hydrogen peroxide is then reunited with the return conduit 11 in the point 22 of intersection. From there, water having a hydrogen peroxide addition can be returned to the pool 2 via the conduit 11. It should be realised that the positioning of the container 15 in Fig. 1 is merely one example of a conceivable embodiment. Accordingly, embodiments are conceivable in which the hydrogen peroxide is added in other positions of the circulation cycle. In principle, it is also conceivable that hydrogen peroxide may be added directly to the pool 2. Embodiments are also conceivable in which hydrogen peroxide is added at more than one point.

Above, conduits 9 and 11 have been described in terms of a conduit 9 that leads from the pool 2 to the filter 3a, 3b, 3c, and a conduit 11 that leads from the filter 3a, 3b, 3c and back to the pool. It should be realised that the conduits 9, 11 can be seen as different parts of one and the same conduit that passes the filter 3a, 3b, 3c. It should be realised that the arrangement according to the invention comprises at least one conduit 9, 11, but that a plurality of conduits also are conceivable. For example, there may be a plurality of conduits that run in parallel with each other.

Sometimes (but not necessarily all the time) one wishes to control the content of hydrogen peroxide in the water and to control the addition depending on the content in question. In order to accomplish this, a conduit can be led from the return conduit to measuring equipment 23 that measures the content of hydrogen peroxide in the water. Fig. 1 shows that a point 21 of intersection on the return conduit 11 is connected to an additional conduit that leads to the measuring equipment 23. Of course, the measuring equipment 23 can also measure other things than the hydrogen peroxide content. For example, the measuring equipment 23 may measure the content of other chemicals than hydrogen peroxide.

The reference 24 is a heat exchanger from which water is returned to the return conduit 11, via a conduit 25. It should be understood that the heat exchanger is a mere example of a possible embodiment of a baths establishment and that other embodiments might be conceived in which there is no heat exchanger.

The reference 18 relates to a container for chemicals, such as chemicals for adjusting pH of the water. Chemicals can be added to the water, e.g. in order to adjust pH, via a conduit 19 that leads from the container 18. It should be understood that the container 18 for additional chemicals, as shown in Fig. 1, is but one mere example of a conceivable embodiment. Embodiments can also be conceived that have no other addition of chemicals but hydrogen peroxide.

As shown in Fig. 2, the establishment may optionally be provided with equipment to permit chlorination of the filters 3a, 3b, 3c. Accordingly, Fig. 2 symbolically shows a container 27 for chlorine that via a conduit 28, 28a, 28b, 28c can supply chlorine to the filters 3a, 3b, 3c. Such chlorination can be made when the pool is not used. It should be realised however that embodiments are also conceivable in which no chlorination of the filter or filters 3a, 3b, 3c takes place.

In normal operation of the establishment shown in Fig. 1 and 2, the valve 31 upstream a filter 3 a is open such that water from the pool 2 can be supplied to the filter 3 a. A lower valve 36 downstream the filter 3a is also open, such that water that has passed through the filter 3a can be led on. A lower valve 33 on the entry side of the filter 3 a is closed during normal operation, which is also the case for an upper valve 35 on the exit side (downstream side) of the filter 3 a.

The structure of a filter 3 is shown in Fig. 3. Here, the filter 3 is shown with a casing 37 that comprises a bottom section 38. The bottom section 38 has a plurality of small openings that suitably may have a diameter of 0.2-1 mm. A layer 4 of small particles rests on the bottom section 38. When the valve 31 is open, water from the pool 2 can enter the filter 3 and flow trough the layer 4 of small particles and out through the bottom section 38. After having passed the bottom section 38, the water may continue through the conduit 11 that leads back to the pool 2. It should be understood that embodiments are conceivable in which the valves 31 and 36 shown in Fig. 3 do not exist.

Water can be led from below and through the layer 4 in order to clean the filter 3. The lower valve 33 shown in Fig. 3 can then be opened and water can be flushed into the filter 3. The, the valves 31 and 36 are closed. Instead the valve 35 is opened, which is otherwise normally closed. Contaminants remaining in the upper part of the layer 4 are then flushed out through the conduit 39.

It should be understood that the additional valves 33 and 35 shown in the figures, as well as the conduits connected to these valves, are mere examples of conceivable embodiments. Accordingly, these can be excluded.

According to the invention, the layer 4 of particles in the filter 3 may be a layer of glass particles, preferably soda lime glass. The inventor of the present invention has previously tried sand filters. It has then proven to be difficult to keep the hydrogen peroxide consumption at an acceptable level. It has been necessary to continuously add additional and considerable amounts of hydrogen peroxide. When performing tests with a layer of particles consisting of glass, the inventor however surprisingly found that the hydrogen peroxide consumption could be considerably reduced. In tests performed by the inventor, the inventor has used particles of soda lime glass.

By soda lime glass is here meant glass that has a composition in percent by weight of: SiO₂ 60 - 75 Na₂O + K₂O 10 - 20

CaO 0 - 16

MgO 0 - 10

Al₂O₃ 0 - 5

It has been shown in tests that a particular type of soda lime glass particles is particularly well suited for the purpose and that it gives very good results. Such particles were constituted of a material having the following chemical composition, in percent by weight:

SiO₂ 68 - 73 Na₂O + K₂O 13 - 15

CaO 8 - 11 Al₂O₃ 0.5 - 2

In tests made with particles of this material, the inventor has been able to establish that the hydrogen peroxide consumption has decreased by more than 90 %. Glass particles suitable for the purpose can be bought for example from the manufacturer Potter Industries, Inc. at the address Potters Europe, European Head Office, St Edmunds House, Lower Baxter Street, Bury St Edmunds, Suffolk IP33 IET, United Kingdom. Potters Industries sell glass particles (glass beads) that are used for blasting. Such glass particles intended for blasting have known been shown to perform excellent in connection with filters for baths establishments that disinfect the bathwater with hydrogen peroxide. In Sweden, such glass particles/beads can be bought from AB TEBECO, Box 40, 301 02 HALMSTAD. AB Tebeco sells such products under the name glass balls (Swedish: "glaskulor"). The particles (glass balls) tested by the inventor had a diameter in the range of 0.42-0.84 mm. Such particles proved to function excellently. It should be understood however that it could be conceived also to use glass balls of some other size, such as larger than 0.84 mm or smaller than 0.42 mm.

The invention is not limited by any particular theoretical explanation of the positive effect, but the invention takes its starting point in actual tests. One possible theoretical explanation for the beneficial effect of the glass balls in the present connection, could be as follows. The sand that previously has been used in the filter or filters contains small amounts of metals that chemically react with the hydrogen peroxide in the water in that will make the hydrogen peroxide decompose. In the soda lime glass balls that have been tested by the inventor, such metals are either missing or are bound by the glass in a way that does not allow a chemical reaction with the hydrogen peroxide.

The thickness H of the layer 4 of glass balls/particles should preferably be at least 600 mm. It could however also be conceived to try thinner layers. Preferably, the layer should be at least 700 mm thick. In many realistic embodiments, the layer 4 could be 700-1000 mm. Of course, the layer 4 could be more than 1000 mm in thickness. For example, the layer 4 could be up to 1200 mm thick, up to 1400 mm thick, or even thicker.

By the invention, the hydrogen peroxide consumption can be considerably decreased in a baths establishment that makes use of hydrogen peroxide instead of or as a supplement to chlorine. Above, the invention has been described with reference to a baths establishment. It should be understood however that the invention can be applied also in other establishments/plants in which water is circulated in a cycle and in which it is desired to disinfect the water for one or other reason, without using chlorine. The invention could for example be used in certain circulating cycles for cooling water.

Claims

1. A method for the treatment of water circulating in a cycle and thereby passing through at least one filter (3a, 3b, 3c), and in which hydrogen peroxide is added to the water, characterised in that the filter (3a, 3b, 3c) comprises a layer (4) of glass particles.

2. A method according to claim 1, characterised in that the glass particles have a diameter of 0.42-0.84 mm.

3. A method according to claim Ior2,characterised in that the particles consist of soda lime glass.

4. A method according to claim 3, characterised in that the soda lime glass that the particles in the filter (3a, 3b, 3c) is composed of, has the following chemical composition in % by weight: SiO₂ 68 - 73

Na₂O + K₂O 13-15

CaO 8-11 MgO 3-5

Al₂O₃ 0.5 - 2

5. A method according to any one of claims 1-4, characterised in that the layer (4) of glass particles in the filter (3a, 3b, 3c) is at least 600 mm thick.

6. A method according to claim 5, characterised in that the layer (4) of glass particles is at least 700 mm thick.

7. A method according to any one of claims l-6,characterised in that the water that is being treated is bathwater in a baths establishment, the water in its circulating cycle being led from a pool (2), through said at least one filter (3a, 3b, 3c) and back to the pool (2).

8. An arrangement for purification of water in a circulating cycle, which arrangement comprises at least one conduit (9, 11) in which water can be led in its circulating cycle, at least one filter (3a, 3b, 3c) connected to said conduit (9, 11), such that water that is led through the circulating cycle can pass through the filter (3a, 3b, 3c), characterised in that the filter (3a, 3b, 3c) comprises a layer (4) of glass particles.

9. An arrangement according to claim 8, characterised in that the glass particles consist of soda lime glass.

10. An arrangement according to claim 8 or 9, characterised in that the arrangement comprises at least one pump in order to lead the water in its circulating cycle.

11. An arrangement according to claim 8 or 9, characterised in that the glass particles have a diameter of 0.42-0.84 mm.

12. An arrangement according to claim 9, characterised in that the soda lime glass that the particles in the filter (3a, 3b, 3c) is composed of, has the following chemical composition in % by weight: SiO₂ 68 - 73

Na₂O + K₂O 13-15

CaO 8-11 MgO 3-5

Al₂O₃ 0.5 - 2

13. An arrangement according to any one of claims 7-11, characterised in that the layer (4) of glass particles in the filter (3a, 3b, 3c) is at least 600 mm thick.

14. An arrangement according to claim 12, characterised in that the layer (4) of glass particles is at least 700 mm thick.

15. An arrangement according to any one of claims 7-13, characterised in that the arrangement comprises means (15, 16) for supply of hydrogen peroxide to the water.

16. Use of soda lime glass particles for the filtration of water in a baths establishment (1) in which hydrogen peroxide is supplied to the bathwater.