EP2262740A1

EP2262740A1 - System and method for treatment of drinking water

Info

Publication number: EP2262740A1
Application number: EP09729152A
Authority: EP
Inventors: Walter Polak
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-04-02
Filing date: 2009-04-02
Publication date: 2010-12-22
Also published as: WO2009121597A1; DE202009018489U1; DE102009016038A1

Abstract

The invention relates to a system for treatment of drinking water, in particular for removal and prevention of a microbiological contamination of drinking water, having in the direction of flow, a particle filter stage (2) and a first UV disinfection stage (3) and also a drinking water sampling point (7), wherein between the first UV disinfection stage (3) and the drinking water sampling point (7) there are arranged in parallel, a hot water preparation unit (4) for heating of the drinking water, a second UV disinfection stage (5) for additional removal and prevention of microbiological contamination of the heated drinking water at the drinking water sampling point (7), and also a connection (14) for at least partial conduction of the heated drinking water in the cycle through the hot water preparation unit (4), and wherein the second UV disinfection stage (5) is located in the direction of flow between the hot water preparation unit (4) and the drinking water sampling point (7) or in the connection (14). The system according to the invention allows a continual provision of cold water and hot water having satisfactory quality both with regard to hygiene-microbiology and also with regard to taste, offers permanent, high dependability against infections, in particular against legionnaires disease, and allows a power-saving operation with little maintenance expense. In addition, the invention relates to a method for treatment of drinking water which uses the system according to the invention.

Description

Plant and process for the treatment of drinking water

The invention relates to a plant for the treatment of drinking water, in particular a plant for the removal and prevention of microbiological contamination of drinking water according to the preamble of claim 1. Furthermore, the invention relates to a process for the treatment of drinking water, in particular a method for removing and preventing microbiological contamination of drinking water according to the preamble of claim 17.

Drinking water systems for the provision of cold and hot water are usually used in buildings, the water intake is usually from a central water supply. In cases in which no central water supply is possible, such plants can also be fed by a local water resources, such as a spring water, from a standing or from a flowing water. Regardless of the type of primary water supply, it must be ensured that the water discharged from a drinking water treatment plant is of a hygienically microbiologically perfect condition, and thus contains no pathogenic microorganisms; Microorganisms or microbes are mostly protozoa of a size of about 0.5 to 5 microns.

Thus, drinking water treatment is essential to human health and is therefore subject to state control, which is carried out in accordance with established legislation and technical regulations based on defined limits for microbiological, chemical and physical parameters of the drinking water to be treated and provided.

The removal of pathogenic microorganisms from drinking water is of central importance, in particular with regard to the prevention of epidemics and infection. Pathogenic microorganisms are certain bacteria (especially Pseudomonas aeruginosa, Salmonella and Escherichia coli), legionella, certain fungi, certain protozoa (in particular Cryptosporidium parvum and Giardia lambilia) and algae species. Even viruses can be counted among the microorganisms. They have a size of about 10 to 300 nm. Viruses in the drinking water, in the absence of their own metabolism, adhere to bacteria as host cells and form with these so-called viral aggregates.

The microorganisms mentioned can occur both free-floating in cold and hot water as well as in the form of biogenic deposits (biofilms) on the water-bearing system components. By using appropriate mechanical micro-filters in drinking water treatment these harmful impurities can largely effectively prevented or removed.

Legionella occupy a special position among the bacteria present in the water. This bacterial species is potentially pathogenic to humans. It is extremely widespread and occurs due to their optimal living conditions at water temperatures between 25 and 50 ⁰ C preferably in hot water installations. The most dangerous Legionella species for humans is Legionella pneumophilia, Legionellosis pathogen or Legionnaires' disease. Because of these characteristics and the resulting widespread spread, legionella pose a serious threat to human health, not only in high-traffic facilities such as public swimming pools, hotels, hospitals and homes. Infection with Legionella occurs in particular by inhaling contaminated aerosols, such as those that occur during showering.

The prior art discloses various measures for killing or neutralizing legionella and for reducing legionella growth in drinking water or process water treatment plants. Here, it is important to distinguish between individual measures or immediate measures ("clean up") and continuously applied measures ("keep clean").

As immediate measures against heavy Legionellenbelastung of drinking or service water systems come in the prior art, primarily the thermal and / or chemical disinfection used. Thermal disinfection is carried out by heating while the chemical disinfection by flushing of polluted water-carrying parts of the plant by means of a suitable highly concentrated oxidative disinfectant (z. B. shock chlorination) is done zen of guided in the system water in a short time more than 70 ⁰ C, thereby causing a destruction of Legionella in both cases. As an example of a device and a method for chemical disinfection, reference is made to WO-Al-03/058009.

As measures for the permanent or continuous reduction of the Legionella growth are in addition to the thermal disinfection by constant temperature of the water in the system to at least 55 ⁰ C and the chemical disinfection with chlorine compounds in particular the ultrafiltration with membrane filters a pore size 0.01 to 0.05 μm known.

In addition, the use of UV radiation or UV disinfection for germicidal or inactivating treatment of drinking water is known from the prior art. The UV disinfection causes a selective oxidation or killing / inactivation of microorganisms under the influence of UV radiation. On the one hand, the UV radiation damages the DNA of the attacking microorganism, which blocks its reproductive capacity. On the other hand, by the UV radiation cell envelope and enzymes of the microorganism are destroyed by oxidants.

Although each of the methods mentioned is suitable for reliably preventing the occurrence of free-floating microorganisms and in particular also Legionella in drinking water. An effective biofilm removal from a drinking water treatment plant and thus a lasting substantial containment of Legionellenbelastung - or at least a significant delay in the recontamination of the plant - can be achieved by any of the above methods per se, but requires at least a combined application of two or more of the above methods.

To realize, for example, a permanent effective reduction of Legionella growth in a drinking water treatment plant with only thermal decontamination is in addition to a permanent water temperature of at least 60 ⁰ C in addition a periodic heating of the guided water in the system to more than 70 ⁰ C. required. Plants that operate on the method of thermal disinfection in conjunction with the above-mentioned high flow temperatures, so far as allow effective protection against microbiological contamination of the water provided therewith. However, the high water temperatures required in this case require an increased corrosion, combined with an abnormal limescale from about 60 ⁰ C in the entire water-bearing system. In addition, high energy, maintenance and personnel costs, so that the operation of such a system is possible only at the cost of significant disadvantages.

This is all the more so as only permanent provisions according to the current state of knowledge can effectively and permanently prevent the growth of Legionella in a drinking water treatment plant.

Also incorporated microorganisms, which are present in protozoa (eg amoebae) and use impurities or biofilm particles as so-called protective colloids, prove to be particularly problematic in drinking water treatment plants. Such impurities, contrary to some statements in the prior art, can not be rendered harmless by means of UV disinfection. Rather, this only succeeds in combination with chemical disinfection using high doses of chlorine or chlorine dioxide, but their continued use would violate existing state regulations and would also adversely affect the taste of such disinfected drinking water.

From the prior art, corresponding plants and methods for drinking water treatment are already known, in which the aforementioned measures are used in combination to combat microbiological drinking water contaminants.

A drinking water treatment of this kind is described in the journal GWF Wasser-Abwasser, Ausgäbe 145 (2004) Nr.2, pages 112 to 117. This comprises a particle filter for the reduction of turbidity and bacterial contaminants, which is followed by a disinfection stage in the form of a UV irradiation device. The disclosed drinking water treatment plant delivers hygienically-microbiologically perfect cold water. ser. The system is particularly suitable for a decentralized water treatment, such as is required in mountain huts by additional use of a prefilter. However, the operation of the plant is both temporally and functionally severely limited by only cold water is provided and the use is limited to 6 months at a time per year, due to the place of use: the plant.

WO-Al-00/21889 discloses a process which, using UV irradiation, prevents the occurrence and growth of pathogenic microorganisms, especially legionella, in both hot and cold water. In detail, the method is a combination of UV disinfection, chemical disinfection (chlorination) and thermal disinfection. The latter takes place at a temperature of at least 70 ⁰ C, for which a first heating device is required. When the water thus heated is not tapped, it circulates through a UV irradiation device and a second heating device, which ensures that a hot water temperature of 60 ⁰ C is not exceeded.

In order to permanently prevent a harmful microbiological burden on the treated drinking water, a total of three different disinfection methods are used in this method. This requires a considerable amount of equipment and high system costs. The chlorination also has a disadvantageous change in the taste of the treated drinking water result. The high water temperatures required also result in high energy costs and maintenance costs, as has already been explained in detail in connection with thermal disinfection in detail.

From EP-Al-O 338 056 a device for the sterilization of heated hot water is known, which allows a reliable reduction of the germ growth at lower energy consumption. The sterilization is carried out using a heat exchanger and a storage container for the water to be heated by the useful volumes of the two containers are matched to one another in such a way that the recoverable in the heat exchanger water temperature is sufficient to a temporary sterilization of the storage container to the tap to ensure streaming service water. By suitable choice of Durchströmdauer, in conjunction with the increased Water temperature, a thermal disinfection is possible, which is complemented by the use of ultrafine filters, which in turn are irradiated with light waves, is performed.

Although it can be ensured in this way that the germicidal water temperature of more than 70 ⁰ C occurs only locally limited. Nevertheless, the high water temperature - even with only periodic application - causes increased calcification of the water-bearing system components, and thus increased energy costs and maintenance costs. The heat exchanger also incurs additional costs.

The present invention has for its object to provide a plant for the treatment of drinking water, which overcomes the disadvantages of the prior art and insofar as a permanent water treatment of cold and hot water to reduce microbiological contamination, in particular Legionella growth, reliably, without the use of chemical additives and without undue and taste negative change of the treated drinking water, which allows this with an operating and storage temperature at which no abnormal limescale occurs permanently within the water-bearing system components and in which no short-term thermal disinfection with high water temperatures is required and therefore with relative low operating, maintenance and personnel costs is operable.

The object of the invention is achieved by a plant for the treatment of drinking water according to claim 1, according to which the plant according to the invention, in particular for removal and prevention of microbiological contamination of drinking water, in the flow direction a particle filter stage and a first UV disinfection stage and a drinking water tapping point has and characterized in that between the first UV disinfection stage and the drinking water tap in a parallel arrangement, a water heating means for heating the drinking water, a second UV disinfection stage for further removal and prevention of microbiological contamination of the heated drinking water at the drinking water tap and a connection to at least partial guidance the heated drinking water are provided in the circulation by the hot water preparation means, the second UV Disinfection stage in the flow direction between the hot water preparation means and the drinking water supply point or - alternatively - provided in the compound.

By combining filtration in the particle filter stage and selective UV oxidation in the first UV disinfection stage, the water entering the system is first freed of microorganisms, especially legionella and protozoa, and bacterial colonization and biofilm formation on the water bearing surfaces within the plant Plant much more difficult. The second UV disinfection step further reduces the number of free-floating microorganisms left over or added to the hot water preparation or piping system. Finally, by the continued, at least partial recycling of the heated and purified in the second UV disinfection stage water in the hot water preparation and then in the second UV disinfection stage permanently ensures a low hot water load by microorganisms.

With the leadership of the heated drinking water in the circulation is also achieved in particular that on the one hand the cold water can be provided in hygienic microbiologically perfect quality and on the other hand, the security against infection by the hot water - especially when showering - is increased.

The targeted cold water disinfection makes it possible to reduce microbial colonization of the cold water strands of a building installation connected to the drinking water treatment plant according to the invention - the water of which inevitably warms up in most cases and thus creates favorable conditions for microbial colonization Mixing with the treated hot water at the place of supply, such as in a shower, an infection is reliably prevented. The location at which the mixing of the provided cold water and hot water takes place (point of use ^λλ ), both two immediately adjacent drinking water supply points, each with an outlet for cold water and hot water include or can be designed as a mixer tap with a common outlet for the mixed water be.

Thus, it is possible with the inventive system in permanent operation, in addition Provide cold water and hot water in hygienic microbiologically perfect quality permanently and an additional increase in security against infection by hot water - especially when showering - to achieve even without unwanted or unacceptable chemical change in the water provided.

The system according to the invention has the additional advantage that there are no material restrictions with regard to the water-bearing system components, so that common pipe materials (matched to corrosion-technical specifications regarding raw water quality) can be used.

Furthermore, the easy installability of the drinking water treatment plant according to the invention proves to be advantageous. Due to the relatively small number of required system components, the space requirement of the system is low and requires so far as a rule no structural changes at the installation site.

Another advantage is the simple operation of the system, their reliable and safe operation and controllability of only a few individual components.

Finally, the drinking water treatment plant according to the invention is characterized by its easy integration into existing plants, which incidentally also applies to their interchangeability with an existing plant.

Advantageous embodiments of the system according to the invention will become apparent from the subject-matter of the dependent claims 2 to 16. These will be explained in more detail below:

The water supplied to the treatment plant according to the invention is first freed of suspended matter in a particle filter stage. This is usually done directly at the place of entry into the building. This ensures that no unfiltered water is fed into the local distribution network. This clarified water is already of high quality and can be used for a variety of purposes. The required reduction of turbidity, or a certain particle spectrum, in the supplied water is achieved by the particle filter stage when the Detrimental load of the filtered water has a value <0.2 NTU, better still, the value of 0.1 NTU below.

The NTU unit refers to the nephelometric turbidity value that is generally between 0.05 and 0.5 NTU for drinking water and, in contrast, for wastewater amounts to 100 to 2000 NTU. Water is said to be virtually particle-free if it has a turbidity value of well below 0.1 NTU, which corresponds to a particle number of about 10 to 50 per ml. It is of essential importance for the quality of the treated drinking water that the turbidity value 0.2 NTU is not exceeded in the course of the particle filter stage, thus already a maximum particle freedom is ensured before a forwarding to subsequent disinfection stages takes place.

The required turbidity values can be achieved by ultrafine filtration or microfiltration, in which particle sizes> 1 μm are reliably filtered out. The filters used in the particle filter stage have a separation limit of absolutely 1 .mu.m for this purpose and are therefore suitable for removing microorganisms such as bacteria and viral aggregates as well as protozoa.

It is particularly preferred to realize this ultrafine filtration with membrane filters which are specially designed for the reduction of turbidity peaks to values <0.1 NTU and for the separation of bacteria and viruses, or in general, the elimination of microbial loads in drinking water treatment. These filters are made from PVDF hollow fibers (PVDF: polyvinylidene fluoride), whose walls have membrane properties and are flown in from the outside to the inside during filter operation.

Filters of this type are available in the form of so-called filter cartridges and as hollow fiber membrane modules. These filter cartridges have a pressure-resistant housing, in which the hollow fibers are bundled, and are intended for direct installation in the raw water line. Their function can be monitored by means of differential pressure measurement, the achievement of a defined pressure difference value signaling the operating limit of the filter. If this limit is reached, the filter cartridge must be replaced.

Hollow fiber membrane modules are operated in contrast in a filter system, the usually have means for automatic backwashing, which allows regeneration of a respective filter module when it reaches its operating limit, also recognizable by a defined differential pressure increase.

In the plant according to the invention for the treatment of drinking water can be used as a particle filter stage both such filter cartridges and hollow fiber membrane modules. While hollow-fiber membrane modules can also be used for raw water with a relatively high particulate load due to the provided backwash capability, filter cartridges without this backflushing option have the limitation that the incoming water must already be relatively particle-free, in particular already has a turbidity value of <0.8 NTU. Such candle filters are characterized by low investment costs, small size in conjunction with high treatment capacity, easy integration into the drinking water treatment plant and their operability without external energy. For economic reasons, particle filter stages of larger plants are preferably realized with hollow fiber membrane modules.

Of particular advantage is the use of membrane filters of the type mentioned as a particle filter stage in the drinking water treatment plant according to the invention but also because the hollow fiber membranes used therein constitute an absolute barrier against bacteria, protozoa and other particles and are in particular independent of the nature of the primary water supply, thus Filtration of water from central water supply systems are just as suitable as water from a local water resources.

An advantageous development of the drinking water treatment plant according to the invention comprises, in addition to a very fine filter with a separation limit of absolutely 1 .mu.m, which is preferably designed in the form of a membrane filter, an upstream 0.5 micron Nominalfϊlter. Such filter elements with separation limits <1 micron nominal are referred to as pre-filter and are relatively inexpensive available. By using such a prefilter in the water supply to a micro-filter, its life can be significantly prolonged, which is reflected in the long run in lower operating costs. Fine particles have a particle retention capacity of> 99.98% for particles> 1 μm and usually represent a combination of depth filter and membrane filter. The combination of pre-filter and micro-particle filter allows the number of particles from a few 100 per ml to well below 100 per ml, which corresponds to a reduction of the turbidity load of 85 to 98%.

Although it is possible with a particle filtration of the specified type, to effectively eliminate both bacteria and virus aggregates and other microorganisms from the primary provided water. However, since microorganisms <1 μm are also contained in the drinking water, it is not possible to filter out all pathogenic or potentially pathogenic microorganisms by means of a particle filter stage, as provided in the drinking water treatment plant according to the invention.

For this purpose, a first UV disinfection stage in the form of a UV irradiation device is provided with which the free-floating microorganisms remaining in the cold water after particle filtration are rendered harmless. In UV disinfection, the water to be sterilized is conducted past a UV emitter whose wavelength is suitable for killing or inactivating the free-floating microorganisms. The effectiveness of the UV disinfection depends directly on the degree of turbidity or the particle freedom of the water to be sterilized, since particles present in the water scatter the UV radiation and thus reduce the efficiency of the UV disinfection. It is therefore to be ensured that the water leaving the particle filter stage has a turbidity load of less than 0.2 NTU. It should also be noted here that host cells (cells which have germs inside) and germ aggregates (such as bacterial aggregates) can not be effectively combated by UV irradiation. Their removal is only effectively possible by suitable filtration, as indicated, prior to UV disinfection.

The UV emitters used in the UV disinfection stage, which are preferably certified, comprise UV lamps in quartz protection tubes and, by their design, ensure that the total water flow through the UV disinfection stage is uniform, preferably at least approximately 400 J / m ^{2 is} applied. The function monitoring of the UV lamps used is carried out using calibrated dard UV sensors, ensuring that the required operating conditions are reliably adhered to and, in particular, the UV emission due to aging and deposit formation within the lamps, due to fluctuations in the mains voltage, the water temperature and the UV absorption of the water due to turbidity does not become inadmissible Way is influenced.

The wavelength of the UV radiation used in the UV disinfection depends on the type of microorganisms to be combated with it. Studies have shown that with irradiation of about 400 J / m ² and a wavelength of about 254 nm all known pathogenic microorganisms can be made harmless. Optimal disinfection results can be achieved with wavelengths of about 240 to 280 nm, in particular in the case of legionellae.

However, the temperature of the irradiated water is also of considerable influence. Surprisingly, it has been shown that an optimum disinfection result can be achieved while maintaining the above-mentioned parameters, if at the same time the water temperature is between about 10 and 35 ^° C., in particular between about 10 and 30 ^° C., better still between about 12 and 17 ⁰ C and most preferably at about 15 ⁰ C; Water at a temperature of about 10 to 35 ⁰ C is referred to as cold water or cold water.

Preferably, the system according to the invention comprises a UV low-pressure radiator for generating a wavelength of about 254 nm as an irradiation device in the first UV disinfection stage. Alternatively, it is also possible to use a UV medium-pressure radiator and / or a UV amalgam low-pressure radiator to generate a wavelength between about 240 and 280 nm in the first UV disinfection stage.

The second UV disinfection stage of the system according to the invention preferably comprises a UV irradiation device for generating a wavelength of about 185 to 400 nm, in particular of about 240 to 400 nm, for the selective UV disinfection within the hot water cycle. The water supplied to the second UV disinfection stage preferably has a temperature between about 35 and 60 ^° C., in particular between about 43 and 58 ^° C.; the range of about 43 to 55 ⁰ C, in particular from about 43 to 47 ⁰ C, leads to particularly advantageous results. The temperature has been very favorable of about 45 ⁰ C proved. Water within the temperature range of about 35 to 60 ° C is referred to as warm water or hot water. An effective UV irradiation to prevent microbiological contamination, especially for fighting Legionella, in hot water is basically possible at wavelengths between about 240 and 400 nm.

Surprisingly, it has been found that an optimum disinfection result is achieved in compliance with the above parameters and with UV radiation in the wavelength range between about 185 and 400 nm, in particular about 240 to 400 nm, when at the same time the water temperature of the irradiated warm water between about 35 and 60 ⁰ C, in particular between about 43 and 58 ⁰ C, with the range of about 43 to 47 ⁰ C is very particularly preferred. In practice, the temperature between about 43 to 47 ⁰ C proves to be particularly advantageous, preferably at about 45 ⁰ C.

Still satisfactory disinfection results are generally also achieved when the temperature of the cold water during irradiation below 10 ⁰ C, in particular up to about 4 ⁰ C, and / or the hot water below about 35 ⁰ C, in particular down to about 30 ⁰ C. is, ie below the above-defined temperature range for cold or hot water in the UV irradiation. The above-defined temperature definitions for the hot water as well as for the cold water can overlap numerically (theoretically) apparent. It is clear to the skilled person that he must choose the temperature within the framework so that there is a sufficient difference between the temperature of the UV-irradiated hot water and the US-irradiated cold water. Conveniently, the difference between the temperature of the hot water and the cold water is at least 5 ° C, especially at least about 10 ⁰ C. In order to achieve optimum results, the temperature difference should be at least about 15 ° C, in particular at least about 2O ⁰ C. In the majority of practical applications of the invention, the advantageous temperature difference is about 25 to 3O ⁰ C. Furthermore, it has surprisingly been found that it is essential for the success of the UV disinfection of hot water, that the wavelength range of about 185 nm to 400 nm, in particular about 240 nm to 400 nm, is selected in the UV irradiation.

The UV irradiation device used in the second UV disinfection stage within the warm water circulation does not fundamentally differ from the irradiation device used in the first UV disinfection stage. It is only necessary to ensure that their operation is reliably possible even in hot water by means of sensor monitoring.

Advantageously, the irradiation device of the second UV disinfection stage of the system according to the invention comprises such a suitable UV medium-pressure radiator and / or UV amalgam low-pressure radiator for generating a wavelength between about 185 and 280 nm, in particular from about 240 to 280 nm.

In a further embodiment of the drinking water treatment plant according to the invention, the hot water preparation means in the form of a hot water boiler with a hot water tank, which defines the Boilernutzraum, and provided with a heater for heating the water in the hot water tank. The DHW tank has an inlet for cold water and an outlet for the produced hot water. In addition, a further water inlet is provided, through which the water which has already been heated once in the boiler can in some cases flow back into the hot water storage tank after passing through the second UV disinfection stage, this warm water circulation being achieved by a fluid-mechanical connection between the outlet of the second UV disinfection stage and the second inlet of the hot water tank is made possible. This far conventional boiler also has a conventional temperature control device which is coupled to the heater in order to maintain a respectively desired hot water temperature in the range of 30 to 60 ⁰ C, in particular about 35 to 60 ⁰ C, constant upright. The heater is designed in a conventional manner as an electric or gas-powered heating.

The optimum temperature of the water in the hot water tank of the system according to the invention is about 43 to 58 ⁰ C; in particular about 43 to 55 ^° C., where a temperature of of about 43 to 47 ⁰ C and in particular of about 45 ⁰ C leads to particularly advantageous results. An operation at the possible upper temperature limit of about 6O ⁰ C, however, is to be avoided, since such an operation is above the service temperature of the produced hot water and therefore uneconomical. Also occurs at temperatures of about 60 ⁰ C and above an abnormal calcification, which as already stated above, does not allow economically viable process more.

With regard to the use of a conventional hot water boiler of the specified type with only one inlet and one outlet, it is advantageous if this one inlet has a fitting in the form of a T-piece, via which both the cold water supply from the first UV disinfection stage Also, the hot water supply from the second UV disinfection stage is made possible in the hot water tank. Preference is given to the water access in the usual way in the lower part of the vertical Boilernutzraumausdehnung.

In a further advantageous embodiment of the drinking water treatment plant according to the invention, the hot water preparation means is designed in the form of a hot water boiler with a cold water access to the hot water tank in the central region of the vertical Boilernutzraumausdehnung, while the hot water inlet is provided for the returned from the second disinfection stage hot water in the lower part of the vertical Boilernutzraumausdehnung. This spatial separation of the inlets of disinfected cold and hot water biofilm formation is reduced in particular in the hot water tank, as due to the different water temperatures, the incoming disinfected cold water from the inlet to the bottom of the hot water tank and the incoming disinfected hot water from the bottom to the top Moved area of the hot water tank, which in any case a water circulation within the hot water tank is supported, which in turn counteracts biofilm formation in the hot water tank.

It is advantageous in the system according to the invention, when the fluid-mechanical connection between the outlet and the inlet of the hot water preparation means for continuous guidance of the heated drinking water in the circuit by the hot water preparation means and the second UV-disinfection stage is formed. This continuous Guiding the heated drinking water in the circuit can on the one hand passive, by appropriate design of the flow cross section of the fluid mechanical connection, which is also preferably thermally insulated, or active, carried out by using a feed pump within the heat-insulated fluid mechanical connection.

However, the advantageous disinfection properties of the system according to the invention also come into play in one embodiment with a fluid-mechanical connection between the outlet and the inlet of the hot water preparation means, which allows a discontinuous guidance of the heated drinking water in the circulation through said system parts. For this purpose, a feed pump is provided in the fluid-mechanical connection, which causes or interrupts the hot water cycle between the second UV disinfection stage and the hot water treatment either time-controlled or temperature-controlled.

Preferably, the plant according to the invention has a connection to the particle filter stage, which is designed for the direct introduction of raw water with a turbid load <0.2 NTU from a central water supply. This makes it possible, even with a particulate filter stage equipped in principle with a prefilter, to reduce the operating costs by omitting the use of the existing prefilter. A cost saving results here by lower maintenance costs, combined with lower operating costs. Such cost-effective pre-filter also allow the waiver of so-called Endstrangfilter.

For the supply from a local water resource, another embodiment of the invention provides for a prefiltration stage upstream of the particle filter stage and having a filter medium with a pore size of> 10 μm. By such a pre-filtration stage weather-related Stosstrübungen can be collected without significantly affecting the function of the particle filter stage, thereby increasing the reliability of the system according to the invention when feeding raw water from a local water resources.

The further development of the system according to the invention by using a backwash filter or a layer filter within the prefiltration stage expands the filter retention system. like the pre-filter in a cost effective and reliable way, so that the function of the particle filter stage is reliably ensured even with large fluctuations in the number of particles in the raw water fed from a local water resources.

In each case an embodiment of the plant according to the invention for the treatment of drinking water is shown in the attached Figures 1 and 2:

1 shows a schematic representation, indicating the flow characteristics of KaIt- and hot water a drinking water treatment plant with a second UV

Disinfection stage between a water heating means and a drinking water supply point;

FIG. 2 shows an alternative embodiment of the plant according to FIG. 1 in a corresponding schematic illustration with a second UV disinfection stage in one

Connection between an outlet and an inlet of a hot water treatment agent.

According to Fig.l the drinking water treatment plant is provided in a building and connected via a line directly to the building raw water supply. The building raw water supply is usually provided by a central or municipal drinking water supply system by providing cold water (KW) of a temperature between about 10 and 30 ⁰ C on a Rohwassera nsch IUSs (1). The water supply to the drinking water treatment plant as well as to a cold water network (15) takes place on the building side via this raw water connection (1).

From the raw water connection (1), a first connecting line (8) leads to the inlet of a particle filter stage (2) which is connected via a second connecting line (9) to a first UV disinfection stage (3). The UV disinfection stage (3) is connected via a third connecting line (10) to a mixing device (6) - "point of use" - thus forming the raw water connection (1), the first connecting line (8), the particle filter stage (2). , the second connecting line (9), the first UV disinfection stage (3) and the third connecting line (10) the cold water treatment line of the plant Mixing device (6) via a fourth connecting line (11) directly a drinking water supply point (7) - the common outlet or drain of the plant for the treated cold and hot water (KW, WW) or mixed water - assigned. In the illustrated embodiment, the drinking water removal point (7) is designed as a shower head. The arrows in the first to third connecting line (8, 9, 10) symbolize the flow direction in the cold water treatment line of the system from the raw water connection (1) to the mixing device (6) and on to the drinking water removal point (7).

A fifth connecting line (12), which branches off from the third connecting line (10) of the cold water treatment line between the first UV disinfection stage (3) and the mixing device (6), forms with a hot water preparation means (4) which is connected by means of a sixth connecting line (13). via a second UV disinfection stage (5) is connected in a fluid-mechanical manner to the mixing device (6) ("point of use"), the hot water treatment line of the installation Cold water treatment line indicated above, to the drinking water outlet (7), the common outlet or drain of the plant for the treated cold and hot water (KW, WW) or mixed water.The arrows in the fifth and sixth connecting line (12, 13) symbolize the flow direction in the hot water treatment line of the system from the mains water supply via the hot water preparation (4) and the second UV disinfection stage (5) to the mixing device (6) and on to the drinking water removal point (7).

The hot water treatment line is thus the cold water treatment line in the third connection line (10) connected in parallel, which is to ensure that only germ-free cold water (KW) can get into the hot water treatment line and on the other, that at the drinking water tap (7) always hygienic microbiological perfect cold water (KW) is available.

In the sixth connection line (13), between the second UV disinfection stage (5) and the mixing device (6) as a "point of use", a seventh connection (14) with the hot water preparation means (4) is provided to the not from the Drinking water tapping point (7) leaked part of the heated in the hot water preparation means (4) and subsequently in the second UV disinfection stage (5) disinfected part of the drinking water (WW) to the hot water preparation means (4) according to the direction of the arrow and this and the inflow from the first UV disinfection stage (3) cold water content (KW), while maintaining a predetermined temperature for hot water in the range between 30 and 60 ⁰ C, by the hot water preparation means (4) and then arranged second UV disinfection stage (5), respectively at least until the next hot water withdrawal via the seventh connection line (14) for further removal and prevention the microbiological contamination of the heated drinking water at the drinking water outlet (7), to be circulated through the hot water preparation (4) and the second UV disinfection stage (5).

The illustrated in Figure 2 alternative embodiment of the system according to the invention differs from the embodiment shown in Figure 1 only in that the second UV disinfection stage (5) instead of in the sixth connecting line (13) in the seventh connecting line (14) between the outlet and the inlet of the hot water preparation means (4) or the hot water return is provided.

With the embodiment of the system according to the invention shown in FIG. 1 as well as in FIG. 2, it is possible to continuously provide cold and warm drinking water in both hygienic-microbiological and taste-perfect quality with a permanently low risk of infection, in particular with regard to legionella diseases. In addition, the illustrated embodiment of the drinking water treatment plant according to the invention allows energy-saving operation with low maintenance.

It is a further object of the present invention to provide a process for the treatment of drinking water, which overcomes the above-mentioned disadvantages of the prior art and so far a permanent water treatment of cold and hot water to reduce microbiological contamination, in particular of Legionella growth Reliable, which can be carried out without the use of chemical additives and which does not cause an impermissible and negative taste of the treated drinking water, which can be carried out at an operating and storage temperature, in which no permanent lime deposition inside Half of the water-bearing system components occurs and in particular no short-term thermal disinfection with high water temperatures is required, and thus with relatively low operating, maintenance and personnel costs is feasible.

This object of the invention is achieved by a method according to claim 17, according to which the inventive method for the treatment of drinking water, in particular for the removal and prevention of microbiological contamination of drinking water, is provided and comprises the following steps: (a) filtration of the drinking water to be treated in one particulate filter stage;

(b) UV disinfecting the filtered drinking water in a first UV disinfecting step;

(c) forwarding a first portion of the drinking water from the first UV disinfection stage to a drinking water outlet; and further characterized by the steps of: (d) passing a second portion of the drinking water from the first UV disinfection stage to a hot water preparation means;

(e) heating the second part of the drinking water in the water heating means;

(f) forwarding a first portion of the heated drinking water from the hot water preparation means to the second UV disinfection stage for further removal and prevention of microbiological contamination of the heated drinking water to the drinking water supply point and return of a second portion of the heated drinking water from the second UV disinfection stage a connection to the hot water preparation means or forwarding of a first part of the heated drinking water from the hot water preparation means to the drinking water removal point and return of a second

Part of the heated drinking water via the second UV disinfection stage by a connection to the hot water preparation for further removal and prevention of microbiological contamination of the heated drinking water; and

(g) circulating the second part of the heated drinking water through the connection, the hot water preparation and the second UV disinfection step, to further remove and prevent the microbiological contamination of the heated drinking water. Thus, in a first process step, the supplied drinking water is filtered in a particle filter stage and then subjected to UV irradiation in a first UV disinfection stage, before a first portion of the supplied drinking water from the first UV disinfection stage is forwarded as cold water to a drinking water supply point while a second part of the supplied drinking water passed from the first UV-disinfection stage to a hot water preparation with a hot water return, where it is heated and then - at least partially - a further UV irradiation in a second UV-disinfection stage is subjected. In this case, the second UV disinfection stage is formed either in the fluid-mechanical connection between the hot water preparation means and the drinking water removal point or, alternatively, in the hot water return line provided between the outlet and the inlet of the hot water preparation means. In the hot water cycle formed to this extent by the second UV disinfection stage, the warm water return and the hot water preparation, the remaining microorganisms that may have newly entered the hot water circulation are killed by UV oxidation in the second UV stage.

The combination of filtration in the particle filter stage and selective UV oxidation in the first UV disinfection stage, as already stated in connection with the system according to claim 1 according to the invention, the water to be treated first sustainable disinfected by microorganisms, especially Legionella , And so a bacterial colonization and biofilm formation on the water-bearing surfaces within the system in any case substantially more difficult. The second UV irradiation in the second UV disinfection stage further reduces the number of free-floating microorganisms still remaining or added to the hot water preparation or piping system. Finally, the continued circulation of at least a portion of the heated drinking water, in each case with renewed heating in the hot water preparation means and respectively renewed UV irradiation in the second UV disinfection stage, permanently ensures a low hot water load by microorganisms.

In other words, the inventive method reliably enables an uninterrupted and cost-effective provision of microbiological high-quality cold and hot water, which also has no taste impairment and contains no chemical additives.

Advantageous embodiments of the method according to the invention are the subject of the dependent claims 18 to 21. Details of these advantageous embodiments emerge directly from the above explanations of the corresponding advantageous developments of the system according to the invention according to claim 1.

The suitability of the method according to the invention and the plant according to the invention for the treatment of drinking water and in particular for the removal and prevention of microbiological contamination of drinking water implies a suitable suitability for industrial water or service water or process water. The invention is expressly directed to a method and a plant for the treatment of industrial water and not limited to the pure drinking water treatment.

An application of the method according to the invention will be explained below with reference to an application example:

example 1

The erfϊndungsgemäße process for the treatment of drinking water, in particular for the removal and prevention of microbiological contamination of drinking water is carried out according to a first application example with the following process steps:

Cold water or raw water with a temperature of 20 ^° C. and a turbidity load of 0.14 NTU (particle number 650 per ml) is provided via a central water supply and then in a particle filter stage with a membrane filter - manufacturer PaII, type Aria ™ LT, cut-off 1 μm absolute - very finely filtered (1st process step); the ultrafine filtration reduces the turbid load to 0.05 NTU (particle number 6 per ml). The treated cold water is now subjected to a first UV disinfection (2nd process step) in a first UV disinfection stage, manufacturer Kryschi, type MH-30eR, illumination 400 J / m ² , wavelength 254 nm, and to a first part to a forwarded to potential drinking water use (3rd step). A second part of the filtered and UV-disinfected cold water is passed into a hot water preparation means in the form of a conventional electrically heated hot water boiler with a thermostat control (4th step), there heated to 45 ⁰ C (5th step) and immediately followed by a second UV Disinfection in a second UV disinfection stage, manufacturer Kryschi, type MH-30eR, illumination 400 J / m ² , wavelength 254 nm subjected (6th step). The treated hot water now flows to a first part directly to the drinking water supply point (7th step), where it is for potential use. The remaining second part of the treated hot water is returned via a connecting line, after the second UV disinfection in the hot water preparation (8th step) and in this cycle, while maintaining the specified relevant adjustment parameters for temperature, illumination and UV wavelength, one continuous sequence of heating and UV disinfection (9th step). The hot water provided at the drinking water outlet has a temperature of 45 ± 1.5 ^° C. and, like the supplied cold water, permanently has a concentration of Legionella below the limit of quantification.

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LIST OF REFERENCE NUMBERS

1 entrance to the building / raw water connection

2 particle filter stage

3 first UV disinfection stage

4 water heater

5 second UV disinfection step

6 mixing device / "point of use"

7 Drinking water outlet / drain

8 first connection line

9 second connection line

10 third connection line

11 fourth connection line

12 fifth connection line

13 sixth connection line

14 seventh connection line

15 cold water network

KW cold water

WW hot water

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Claims

claims

1. Plant for the treatment of drinking water, in particular for the removal and prevention of microbiological contamination of drinking water, having in the direction of flow, a particle filter stage (2) and a first UV disinfection stage (3) and a drinking water tapping point (7), characterized in that between the first UV disinfection stage (3) and the drinking water removal point (7) in parallel arrangement a hot water preparation means (4) for heating the drinking water, a second UV disinfection stage (5) for further removal and prevention of microbiological contamination of the heated drinking water of the

Drinking water tapping point (7) and a connection (14) for at least partially guiding the heated drinking water in the circuit through the hot water preparation means (4) are provided, wherein the second UV disinfection stage (5) in the flow direction between the hot water preparation means (4) and the drinking water removal point (7) or in the connection (14) is provided.

2. Plant according to claim 1, characterized in that the particle filter stage (2) for setting a turbidity load of <0.2 NTU, in particular of <0.1 NTU, is formed.

3. Plant according to claim 1 or 2, characterized in that the particle filter stage (2) is designed as a very fine filter, in particular as a membrane filter, with a separation limit of absolutely 1 micron.

4. Plant according to claim 1 or 2, characterized in that the Partikelfilterstu- Fe (2) comprises a micro-filter, in particular a membrane filter, with a cut-off of absolute 1 micron and an upstream 0.5 micron nominal filter.

5. Plant according to one of claims 1 to 4, characterized in that the first UV disinfection stage (3) as a UV irradiation device for generating a Wei- lenlänge of 240 to 280 nm, in particular of about 254 nm, for the disinfection of water at a temperature between about 10 and 30 ⁰ C, in particular between about 12 and 17 ⁰ C and especially of about 15 ⁰ C is formed.

6. Plant according to claim 5, characterized in that the UV irradiation device comprises a UV low-pressure radiator, for generating a wavelength of about 254 nm.

7. Plant according to one of claims 1 to 4, characterized in that the second UV disinfection stage (5) as a UV irradiation device for generating a wavelength of about 185 to 400 nm, in particular from about 240 to 400 nm, for the disinfection of water with a temperature between about 35 and 60 ⁰ C, in particular between about 43 and 58 ⁰ C and especially of about 45 ⁰ C is formed.

8. Plant according to claim 7, characterized in that the UV irradiation device comprises a UV medium-pressure radiator, for generating a wavelength of about 185 to 280 nm, in particular from about 240 to 280 nm.

Installation according to any one of Claims 1 to 8, characterized in that the water heating means (4) comprise a hot water boiler with a first inlet for cold water, an outlet for hot water and a second inlet for the cold water

Forming the water cycle through the connection (14), the hot water boiler and the second UV disinfection stage (5).

An installation according to claim 9, characterized in that the first inlet and the second inlet are designed as a common inlet in such a way that the water inlet into the boiler utility space takes place in the lower area of the vertical boiler utility space expansion.

An installation according to claim 9, characterized in that the first inlet is formed in such a way that the water inlet into the boiler utility space takes place in the central region of the vertical boiler utility space, and that the second inlet is formed in such a way that the water inlet into the water inlet Boiler utility room in the lower Area of vertical boiler floor space expansion done.

12. Installation according to any one of claims 1 to 11, characterized in that the connection (14) for the continuous guidance of the heated drinking water in the circuit by the hot water preparation means (4) and the second UV-disinfection stage (5) is formed.

13. Plant according to at least one of claims 1 to 11, characterized in that the connection (14) for the discontinuous guidance of the heated drinking water in the circuit through the hot water preparation means (4) and the second UV

Disinfection stage (5) is formed.

14. Installation according to any one of claims 1 to 13, characterized in that the particle filter stage (2) has a connection (1) for connection to a central water supply.

15. Plant according to claim 1, characterized in that the particle filter stage (2) is preceded by a prefiltration stage with a pore size of> 10 μm, and in that the prefiltration stage has a connection for connection to a local water source.

16. Plant according to claim 15, characterized in that the prefiltration stage comprises a backwash filter or a layer filter.

17. A process for the treatment of drinking water, in particular for the removal and prevention of microbiological contamination of drinking water, comprising the process steps:

(a) filtration of the drinking water to be treated in a particle filter stage (2);

(b) UV disinfection of the filtered drinking water in a first UV disinfection stage (3);

(c) forwarding a first portion of the drinking water from the first UV disinfection stage (3) to a drinking water removal point (7); characterized by the further method steps: (d) forwarding a second portion of the drinking water from the first UV disinfection stage (3) to a hot water preparation means (4);

(e) heating the second part of the drinking water in the hot water preparation means (4); (F) forwarding a first portion of the heated drinking water from the hot water preparation means (4) via the second UV disinfection stage (5) for further removal and prevention of microbiological contamination of the heated drinking water to the drinking water supply point (7) and return a second portion of the heated drinking water from the second UV disinfection stage (5) through a connection (14) to the hot water preparation means (4) or

Transmission of a first portion of the heated drinking water from the hot water preparation means (4) to the drinking water removal point (7) and return of a second portion of the heated drinking water via the second UV disinfection stage (5) by a connection (14) to the hot water preparation means (4) for further Removal and prevention of microbiological contamination of the heated drinking water; and

(g) circulating the second part of the heated drinking water through the connection (14), the hot water preparation means (4) and the second UV disinfection stage (5), for further removal and prevention of the microbiological contamination of the heated drinking water.

18. The method according to claim 17, characterized in that by means of the particle filter stage (2) a turbidity load of the drinking water of <0.2 NTU, in particular of <0.1 NTU, is set.

19. The method according to claim 17 or 18, characterized in that the drinking water of the first UV disinfection stage (3) having a temperature between about 10 and 30 ⁰ C, in particular between about 12 and 17 ⁰ C and especially of about 15 ⁰ C, is supplied, and that the UV irradiation in the first UV disinfection stage (3) with a wavelength of 240 to 280 nm, in particular of about 254 nm, takes place.

20. The method according to claim 17 or 18, characterized in that the drinking water of the second UV disinfection stage (5) with a temperature between about 35 and 60 ⁰ C, in particular between about 43 and 58 ⁰ C and especially of about 45 ⁰ C, is supplied, and that the UV irradiation in the second UV-disinfection stage (5) with a wavelength of about 185 to 400 nm, in particular from about 240 to 400 nm, takes place.

21. The method according to any one of claims 17 to 20, characterized in that the guidance of the second part of the heated drinking water in the circuit through the connection (14), the hot water preparation means (4) and the second UV disinfection stage (5) continuously or discontinuously.

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