DE102009051489A1 - Method for operating a water treatment system and for the implementation of the method suitable water treatment system - Google Patents

Abstract

When operating a water treatment system (1), in particular a pure or ultrapure water treatment system, in which water is fed to a circuit (2) in a water treatment plant, is treated by a circulation in the circuit (2) and then discharged from the circuit (2), Effective disinfection can be achieved in a short time by adding ozone to the water circulating in circuit (2) in a disinfection operation or by generating ozone in the circulating water of circuit (2), this ozone with the circulating water by at least one Part of the circuit (2) flows and is then removed from the circuit (2).

Description

The invention relates to a method for operating a water treatment system, in particular a pure or ultrapure water treatment system, according to the preamble of patent claim 1 and a suitable for carrying out the method water treatment system according to the preamble of claim 10.

For laboratory diagnostics, molecular and microbiology, reproductive medicine and many other applications, especially pure water with a very low conductivity (eg <0.1 μS / cm at 25 ° C) and a very low Total Organic Carbon (TOC) is used. - Content (eg <10 ppb) is required. Such pure water, also referred to as "pure water" or "ultrapure water" depending on the degree of purity, can be produced by special water treatment systems, also referred to as "pure or ultrapure water treatment systems".

In such systems known in the art, water to be treated, usually drinking water, is first desalted in a reverse osmosis module, softened in a conditioning module and then deionized in an electro-deionization cell. For removal of organic material, germs, endotoxins, DNase, RNase, DNA and other particles, the water is then fed to another water treatment device, for example a device for ultraviolet (UV) oxidation of organic material in water, followed by a Polisher module for removing organic material and reducing electrical conductivity with activated carbon material and ion exchange resin, an ultrafiltration module and a sterile filter. The treated pure or ultrapure water can be supplied to a consumer via an outlet arranged in the direction of flow of the water downstream of the water treatment device and optionally further distribution devices. To maintain the purity of the pure or ultrapure water while the water is circulated by means of a pump continuously or intermittently in a cycle through this water treatment device.

For example, the UV oxidizer may comprise a UV light source that generates light having a wavelength of 185 nm and 254 nm. The light with the wavelength of 185 nm generates ozone in water. The light with the wavelength of 254 nm wavelength reacts with the ozone to produce hydroxyl radicals. These radicals oxidize organic matter in the water to carbon dioxide, water and by-products such as hydrogen peroxide. These by-products are removed by the activated carbon material and ion exchange resin contained in the Polisher module, allowing for very low TOC values of <1 ppb.

In order to ensure the desired high purity of the treated water, the water circuit and a distribution system connected to it must be disinfected from time to time. This is done according to the prior art by adding chlorine, sodium hydroxide or other chemical disinfectants. As problematic for their use, however, proves that they require relatively long exposure times and that they produce to other chemical residues that can pollute the water treatment system and therefore must be completely removed from the water treatment system before delivering pure or ultrapure water to a consumer can be. Known clean or ultrapure water systems therefore require up to 8 hours for disinfection and subsequent cleaning flushing of the system.

Proceeding from this, it is an object of the present invention to provide a method by which the disinfection of such a water treatment system can take place in a much shorter time. It is also an object of the present invention to provide a particularly suitable for carrying out the method water treatment system.

The solution of the object directed to the method is achieved by a method according to claim 1. Advantageous embodiments of the method are the subject of claims 2 to 9. The solution directed to the water treatment system succeeds by a water treatment system according to claim 10. Advantageous design of the water treatment system are the subject of Claims 11 to 15.

In the method according to the invention, in a disinfecting operation for disinfecting the water treatment system, ozone is supplied to the water circulating in the circuit, or ozone is generated in the circulating water of the circuit. Ozone is a much stronger disinfectant than chlorine, for example, and does not leave any chemical residue or unwanted by-products if used correctly. Ozone rapidly destroys bacterial cells, enabling relatively short disinfection cycles. In comparison, chlorine must be absorbed by the cell to destroy the organism. Therefore, chlorine requires comparatively higher concentrations and longer disinfection times. The ozone flows with the circulating water through at least part of the circulation, disinfecting all the components of the circuit with which it comes into contact. Subsequently, the ozone is removed from the circulation.

Preferably, in the disinfecting operation, the ozone circulates through the entire cycle at least once, preferably even several times. In this way it can be ensured that the entire circuit including all connected components and distribution devices is reliably disinfected.

According to a particularly advantageous embodiment, in the water treatment operation, the circulating water is irradiated with UV light of a UV light source and irradiated in the disinfecting operation for removing the ozone from the circulation, the water flowing through the circuit also with UV light of this UV light source. As a result, the ozone is converted into oxygen and thus removed from the water of the circuit. Consequently, a UV light source used in the water treatment operation for the oxidation of the water is also used in the disinfection operation to remove the ozone from the circulation. As a result, an additional component for removing the ozone in the circuit can be omitted. Alternatively, it is also possible for the ozone by other known methods, such. B. by activated carbon to remove from the circulating water.

An undesired too early removal of the ozone required for the disinfection due to irradiation with UV light of this light source can be prevented that in the disinfecting operation during the supply or production of ozone and the flow of ozone in the circuit, the circulating water with the UV light of the light source is irradiated.

In order to avoid that a consumer removes ozone-containing water from the water treatment system, it is advantageous during the disinfection operation to prevent a discharge of water for a consumer of the water from the circulation.

In the disinfecting operation, when the ozone having a predetermined concentration in the water flows through the circuit for a predetermined time, a desired sufficient disinfection of the circuit can be ensured.

It has been found that sufficient disinfection is possible by passing the ozone through the circuit at a concentration of 0.01 to 0.5 mg per liter of water for at least 10 minutes.

For regular disinfection of the water treatment system of the water treatment operation is advantageously interrupted at predetermined intervals for a disinfection operation.

Preferably, the ozone is generated by an electrolysis of oxygen in water. The electrolysis can be done directly in the circulating through the water, d. H. The ozone is generated in the circulating water of the circuit, or the ozone can be generated outside the circuit and then fed to the circuit.

A water treatment system according to the invention, in particular pure or ultrapure water treatment system, for carrying out the method described above comprises a water circuit with an inlet, an outlet, a pump for circulating water through the water cycle and a water treatment device arranged in the circuit. The water treatment system comprises one with the circuit connected, in particular arranged in the circuit, ozone generating means and arranged in the circuit ozone removal device. The advantages mentioned in connection with the method according to the invention also apply correspondingly to the water treatment system according to the invention.

For targeted automated control of ozone production by the ozone generating device and ozone removal by the ozone removal device, the water treatment system preferably has a control device.

In order to prevent ozone-containing water from being discharged to a consumer, the control device is advantageously designed such that it blocks the outlet when ozone is generated by the ozone generating device and when the generated ozone flows through the circuit.

According to a particularly advantageous embodiment, the ozone removal device is a UV light source of the water treatment device, which serves to purify the water by irradiation with UV light.

According to a further advantageous embodiment, the control device is designed such that it prevents the irradiation of the water by the UV light source in an ozone generation by the ozone generating device and a flow of ozone generated by the circuit.

The ozone generating device is preferably an electrolysis cell arranged in the circuit.

The invention and further advantageous embodiments of the invention according to features of the subclaims are explained in more detail below with reference to exemplary embodiments in the figures. Show:

1 A first embodiment of a water treatment system,

2 A second embodiment of a water treatment system,

3 A third embodiment of a water treatment system.

An in 1 shown inventive pure or ultrapure water treatment system 1 includes a water cycle 2 with an inlet 3 , a lockable outlet 4 and with a pump 5 for the circulation of water through the water cycle 2 , In the cycle 2 is in the flow direction of the water between the inlet 3 and the outlet 4 a water treatment device 6 arranged, which is a UV oxidation module 10 , a polisher module 11 and an ultrafiltration module 12 includes, in the flow direction of the water in a row in the cycle 2 are arranged.

The outlet 4 is preferably designed as a dispensing dispenser. At the outlet (dispenser) 4 is a sterile filter 7 connected. Circuit side is the outlet 4 via a return line 8th with the inlet 3 connected.

For rinsing the ultrafiltration module 12 is at the output one through a valve 20 lockable sewer 21 connected.

In the flow direction of the water is in the circulation 2 between the pump 5 and the water treatment device 6 an ozone cell 9 arranged for the production of ozone.

To the inlet 3 is a connection cable 30 for the supply of water to the circuit 2 connected. About this connection line 30 and a closable valve disposed therein 31 For example, pretreated water (for example desalinated and softened drinking water) can be supplied to the circuit in previously unprocessed stages of preparation, which is finally fed into a deionization module prior to feeding 32 , the Z. B. is filled with mixed bed resin is deionized.

The UV oxidation module 10 serves in cooperation with the Polisher module 11 for removal of organic materials. The UV oxidation module 10 includes for this purpose a UV light source 15 for irradiating the water flowing through the module with UV light. The light source 15 generates light with a wavelength of 185 nm and 254 nm. The Polisher module 11 has activated carbon and ion exchange resin to remove organic matter and reduce conductivity. The ultrafiltration module 12 For example, it consists of a hollow fiber material and serves to reduce endotoxins and to remove DNase, RNase and DNA from the water.

A control device 13 serves to control the entire water treatment system 1 and controls via control line 14 the pump 5 , the ozone cell 9 , the light source 15 , the outlet (dispenser) 4 and the position of the valves 20 and 31 , In addition, it is not shown with sensors for measuring various parameters such. As the conductivity of the water, the flow rates through the circuit, the temperature of the water in the circuit, etc. connected.

In a water treatment plant of the water treatment system 1 gets the circulation 2 over the inlet 3 pretreated water supplied and by means of the pump 5 continuously or intermittently through the cycle 2 circulated. The water flows in the cycle starting from the inlet 3 over the pump 5 , the ozone cell 9 , the UV oxidation module 10 , the polishing module 11 , the ultrafiltration module 12 , the outlet 4 and the return line 8th back to the inlet 3 , The ozone cell 9 is by the control device 13 deactivated, ie it does not generate ozone.

The light of the light source 15 of the UV oxidation module 10 with the wavelength of 185 nm generates ozone in the passing water. The light with the wavelength of 254 nm wavelength reacts with this ozone and thus produces Hydroxil Radicals (ORA). These radicals oxidize organic matter in the water to carbon dioxide, water and by-products such as hydrogen peroxide. These by-products are removed by the activated carbon material and ion exchange resin contained in the Polisher module, so that very low TOC values of <1 ppb and very low conductivity of <0.1 μS / cm at 25 ° C can be achieved.

The ultrafiltration module reduces endotoxin levels and removes DNase, RNase and DNA from the water. Any remaining germs and particles are released from the circulation when draining water 2 for a consumer through the sterile filter 7 away.

For disinfection of the circulation 2 is by the controller 13 the water treatment plant on the basis of predetermined criteria, eg. B. at regular intervals, interrupted and the water treatment system 1 switched to a disinfection operation.

For this purpose, by the control device 13 the ozone cell 9 activated so that it generates ozone by electrolysis of oxygen in the water flowing through it. This ozone flows at a predetermined concentration for a predetermined time with the circulating water several times through the entire cycle and disinfects all components of the cycle. As it turns out, it is sufficient for the disinfection, if the ozone flows with a concentration of 0.01-0.5 mg per liter of water for at least 10 minutes through the circuit and is in contact with all components of the circuit. Depending on the system and field of application, however, even lower concentrations and contact times may be sufficient for adequate disinfection.

So that the ozone in the disinfection operation by the light source 15 the UV oxidation stage is not immediately removed, is during the generation of ozone and the flow of ozone in the circuit 2 the circulating water not with the UV light of the light source 15 irradiated. This is done by the controller 13 This prevents them from the light source 15 off.

In addition, during the disinfection operation by the controller 13 a discharge of water for a consumer of the water over the outlet 4 out of the cycle 2 prevented.

To end the disinfection operation is by the controller 13 the ozone production by the ozone cell 9 switched off and to remove the ozone from the circulation 2 the light source 15 of the UV oxidation module 10 switched back on. As a result, the water flowing through the circuit is irradiated with UV light having a wavelength of 254 nm, whereby the ozone is converted into oxygen and thus from the water of the circuit 2 Will get removed. Any resulting organic byproducts will pass through the activated carbon and ion exchange resin of the Polisher module 11 away. However, oxygen remaining in the water is harmless in relation to the quality of the water in almost all areas of application of a pure or ultrapure water system.

After disinfection is by the controller 13 the water treatment system 1 switched again from the disinfection operation in the water treatment operation and allows a discharge of water to a consumer.

A particular advantage is that the UV light source 15 , which is used to purify the water in the water treatment operation, also serves to remove the ozone in the disinfection operation.

By previously disinfecting the system with ozone, the TOC content and the bacterial endotoxin content in the treated water can be further reduced.

If during the circulation of the ozone in the disinfection mode that in the Polisher module 11 If the ion exchange resin contained must be protected from the ozone, the water in this operating case can also be protected by a bypass 16 on the polisher module 11 be passed. The bypass line 16 is only blocked again when at the end of the disinfection operation, the ozone by the irradiation with UV light of 254 nm back out of circulation 2 should be removed. Opening and blocking the bypass 16 can also be controlled by the control device 13 respectively. Additionally, after locking the bypass line 16 the ultrafiltration module 12 Briefly flushed with concentrate and the wastewater through the sewer 21 be removed.

For disinfection of the outlet (dispenser) 4 and the sterile filter 7 In the disinfection mode, these can be briefly removed with ozonated water from the circulation 2 be rinsed. This can also be the sterile filter 7 removed and only the outlet (dispenser) 4 be rinsed.

At an in 2 the embodiment shown is the ozone cell 9 not upstream of the UV oxidizer 10 but downstream of the UV oxidizer 10 in a bypass 33 to the polishing module 11 and the ultrafiltration module 12 arranged. The through a valve 34 lockable bypass 33 branches from a line connection 35 between the UV oxidizer 10 and the polishing module 11 and ends in a line connection 36 between the ultrafiltration module 12 and the outlet (dispenser) 4 , In disinfection mode, the valve 34 by the control device 13 during the ozone production and circulation of the ozone open, allowing the ozonated water through the bypass 33 and thus on the polishing module 11 and the ultrafiltration module 12 flows past. During this time is the UV light source 15 in the UV oxidizer 10 off. If at the end of the disinfection operation to remove the ozone, the UV light source 15 is turned on again, is by the controller 13 also the valve 34 closed and thus the bypass 33 locked, allowing the water back through the polishing module 11 and the ultrafiltration module 12 flows. If the ultrafiltration module 12 is insensitive to ozone or if the ultrafiltration module 12 It can also be sufficient with the bypass line at regular intervals replaced by a new ultrafiltration module 33 only the polishing module 11 to bypass, ie the bypass 33 then flows into a line connection 37 between the polishing module 11 and the ultrafiltration module 12 one.

At an in 3 the embodiment shown is the ozone cell 9 unlike in 1 and 2 shown embodiments downstream of the polishing module 11 in the line connection 37 between the polishing module 11 and the ultrafiltration module 12 arranged. In this case, the UV light source 15 the UV oxidizer 10 in the disinfection mode also during the generation and the flow of ozone through the circuit 2 remain switched on. That in the ozone cell 9 generated ozone then flows through the outlet (dispenser) 4 , the return line 8th and the pump 5 in the UV oxidation device 10 in which the ozone before its supply to the polishing module 11 is removed from the water. An additional bypass for the polishing module 11 is therefore not needed. Incidentally, contains the polishing module 11 Usually at its entrance activated carbon, so that any remaining in the water and in the polishing module 11 flowing ozone is removed before contact with the ion exchange resin. If desired, also in this solution during the disinfection operation, the ultrafiltration module 12 be bridged by a bypass line.

In all cases described above, the polishing module 11 Instead of being characterized by a separate bypass line, it is also estimated that before ozone-containing water that the polishing module 11 or a polishing cartridge contained therein before beginning the disinfection operation is removed and replaced by a bridging tube. After the disinfection operation, the bridging pipe can then be replaced by the polishing module 11 or a polishing cartridge contained therein be replaced. In this case, the bridging tube is preferably by a new polishing module 11 or a new polishing cartridge replaced to introduce a bacteria that adheres to the previous (old) polishing module 11 or on the previous (old) polishing cartridge to avoid accumulation.

In all embodiments described above, the sterile filter 7 instead of after the outlet (dispenser) 4 also upstream of the outlet (dispenser) 4 ie between the ultrafiltration module 12 and the outlet (dispenser) 4 in the cycle 2 be arranged.

In principle, it is then possible in such a case, the ozone cell 9 downstream of the ultrafiltration module 12 in a line connection between the ultrafiltration module 12 and the sterile filter 7 to arrange.

Regardless of the exact arrangement of the ozone cell, the invention enables a rapid and effective disinfection of a water treatment system, in particular a pure or ultrapure water treatment system, described above, without having to use hazardous chemicals that are difficult to remove from the system.

The exact exposure time and / or concentration of the ozone also depends on the amount of ozone consumed by a reaction with the filter material of the various filters and a reaction of the ozone with organic material, pyrogens and bacteria contained in the filters becomes. To compensate for this consumption, a comparatively higher ozone concentration in the water and / or a longer exposure time may be necessary for adequate disinfection.

Claims (15)

Method for operating a water treatment system ( 1 ), in particular a pure or ultrapure water treatment system, in which water is circulated in a water treatment plant ( 2 ) is recycled by circulation in the circuit and then out of the circuit ( 2 ) is discharged, characterized in that for disinfecting the water treatment system ( 1 ) in a disinfection plant - in the cycle ( 2 circulating water is supplied to ozone or in the circulating water of the circuit ( 2 ) Ozone is generated, - this ozone with the circulating water through at least part of the cycle ( 2 ) flows and - then out of the cycle ( 2 ) Will get removed. A method according to claim 1, characterized in that in the disinfecting operation, the ozone at least once through the entire cycle ( 2 ) circulates. Method according to one of the preceding claims, characterized in that in the water treatment operation, the circulating water with UV light of a UV light source ( 15 ) and that in the disinfecting operation for the removal of ozone from the circuit ( 2 ) that through the cycle ( 2 ) flowing water also with UV light of this UV light source ( 15 ) is irradiated. A method according to claim 3, characterized in that in the disinfecting operation during the supply or production of the ozone and the flow of ozone in the circuit ( 2 ) the circulating water does not interfere with the UV light of the UV light source ( 15 ) is irradiated. Method according to one of the preceding claims, characterized in that during the disinfection operation, a discharge of water for a consumer of the water from the cycle ( 2 ) is prevented. Method according to one of the preceding claims, characterized in that in the disinfecting operation, the ozone with a predetermined concentration in the water for a predetermined time through the circuit ( 2 ) flows. A method according to claim 6, characterized in that the ozone at a concentration of 0.01-0.5 mg per liter of water for at least 10 minutes through the circuit ( 2 ) flows. Method according to one of the preceding claims, characterized in that the water treatment operation is interrupted at predetermined time intervals for a disinfection operation. Method according to one of the preceding claims, characterized in that the ozone is produced by an electrolysis of oxygen in water. Water treatment system ( 1 ), in particular pure or ultrapure water treatment system, for carrying out the method according to one of the preceding claims, with a water cycle ( 2 ) with an inlet ( 3 ), an outlet ( 4 ), a pump ( 5 ) for the circulation of water through the water cycle ( 2 ) and a water treatment device ( 6 ), characterized by one with the circuit ( 2 ), in particular in the cycle ( 2 ), ozone generating device ( 9 ) and an ozone removing device disposed in the circuit. Water treatment system ( 1 ) according to claim 10, characterized by a control device ( 13 ) for controlling the ozone production by the ozone generating device ( 9 ) and ozone removal by the ozone removal device. Water treatment system ( 1 ) according to claim 11, characterized in that the control device ( 13 ) is designed in such a way that, when ozone is generated by the ozone generating device ( 9 ) and with a flow of the generated ozone through the circuit ( 2 ) the outlet ( 3 ) locks. Water treatment system ( 1 ) according to one of claims 10 to 12, characterized in that the ozone-removing device is a UV light source ( 15 ) of the water treatment device ( 6 ), which serves to purify the water by irradiation with UV light. Water treatment system ( 1 ) according to claim 13, characterized in that the control device ( 13 ) is designed in such a way that, when ozone is generated by the ozone generating device ( 9 ) and with a flow of the generated ozone through the circuit ( 2 ) the irradiation of the water by the UV light source ( 15 ) prevented. Water treatment system ( 1 ) according to one of claims 9 to 14, characterized in that the ozone generating device ( 9 ) one in the cycle ( 2 ) is arranged electrolytic cell.

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