Device and method for treating drinking water

Abstract

Methods for the treatment of drinking water, in which drinking water to be treated in the extraction operating state Reverse osmosis operation is carried out through a semipermeable membrane (11) and separated into permeate and concentrate, characterized by the fact that During the extraction state, a portion of the permeate flows into a pressure tank (4), thereby creating a permeate reservoir in the pressure tank (4) and pressurizing it, and during the standby state, a portion of the permeate passes through the membrane (11) by means of the overpressure, thereby displacing the concentrate on the concentrate side of the membrane (11) and possibly removing any deposits present on the concentrate side of the membrane (11).

Description

Field of invention

[0001] The invention relates to a device and a method for treating drinking water using a reverse osmosis system. Background of the invention

[0002] It is known to treat drinking water using reverse osmosis (RO) processes. These processes utilize reverse osmosis systems in which a semipermeable membrane is arranged within a container, dividing it into two chambers. The semipermeable membrane is impermeable to one or more dissolved substances in the water. The concentration of these substances in the water can be reduced by introducing raw water (feed) into the container and forcing it against the membrane under pressure.

[0003] During this process, water molecules pass through the membrane and leave the first chamber, retaining the dissolved substances. These substances are then trapped by the membrane and accumulate in the first chamber. The water molecules passing through the membrane enter the second chamber of the container and form the main component of the water extracted from the reverse osmosis system as the "permeate." The substances retained by the semipermeable membrane are concentrated in the "concentrate" or "wastewater."

[0004] Reverse osmosis systems are usually operated until, due to contamination and encrustation of the membrane, the efficiency becomes so poor that continued operation is no longer worthwhile and the membrane must be replaced or cleaned.

[0005] Another disadvantage of reverse osmosis systems used intermittently is that, in standby mode, a liquid, usually water, remains on the feed or concentrate side of the RO membrane. This liquid contains a concentration of dissolved salts or organic compounds whose concentration is the average of the feed and concentrate concentrations. The ion concentration can be determined by measuring the water's conductivity.

[0006] The following example illustrates this problem. The "yield" of reverse osmosis is given as the ratio between the amount of practically salt-free permeate and the feed volume. The higher this value, the less concentrate is produced.

[0007] Case 1: With an influent conductivity of 500 µS / cm (microsiemens per centimeter) and a reverse osmosis yield of 50%, the conductivity in the concentrate is approximately 1000 µS / cm. This results in an average concentration on the concentrate side of the membrane of 750 µS / cm.

[0008] Case 2: With an influent conductivity of 500 µS / cm (microsiemens per centimeter) and a reverse osmosis yield of 75%, the conductivity in the concentrate is approximately 2000 µS / cm. This results in an average concentration on the concentrate side of the membrane of 1250 µS / cm.

[0009] Thus, a concentration gradient exists between the concentrate and the permeate, which is generally greater than 20 µS / cm. Consequently, the salts, heavy metals, and other pollutants, which are retained at least 98% during operation, nevertheless diffuse to the permeate side during standby. Diffusion only stops when the concentrations equalize. Therefore, the permeate becomes contaminated after just a few minutes in standby mode.

[0010] In the case of under-counter reverse osmosis systems at the point of use, stagnation times, i.e., the duration of the standby state, are very long, as only a few liters of water are drawn per day; consequently, there are few water withdrawals. The permeate quality is therefore usually very poor at the beginning of the withdrawal period.

[0011] The permeate can therefore be flushed from time to time. However, the problem here is that the flushing line is connected to the sewer, and bacteria can thus enter the permeate.

[0012] Reverse osmosis systems with a backwash for the membrane are known from documents DE 10 2016 101 000 A1 and DE 20 2016 100 262 U1.

[0013] Reverse osmosis systems are also known from the documents DE 10 2008 006 501 A1, DE 60 2005 003 602 T2, DE 42 13 714 C1 and DE 43 40 318 C1. Object of the invention

[0014] In contrast, the invention is based on the objective of at least reducing the aforementioned disadvantages of the prior art.

[0015] In particular, it is an object of the invention to provide a method and a device for the treatment of drinking water by means of reverse osmosis, which extend the service life of the semipermeable membrane or improve the yield of the reverse osmosis system.

[0016] In particular, a further object of the invention is to provide a method and a device for the treatment of drinking water by means of reverse osmosis, in which the re-salination of the permeate is reduced and in particular substantially prevented in discontinuous operation. Solution using the invention

[0017] The object of the invention is already solved by a method for the treatment of drinking water in which, in the extraction operating state, drinking water to be treated is conveyed through a semipermeable membrane in reverse osmosis operation and separated into permeate and concentrate, and in which, during the standby operating state, a part of the permeate passes through the membrane by means of an overpressure and thereby displaces the concentrate on the concentrate side of the membrane and possibly removes any deposits present on the concentrate side of the membrane.

[0018] The invention is further solved by a device for treating drinking water, which has at least one reverse osmosis tank which is divided into at least two chambers by at least one semipermeable membrane, wherein the first chamber has an inlet for the water to be treated and an outlet for the concentrate and the second chamber has an outlet for the treated water, wherein the device comprises at least one pressure vessel which is connected to the outlet of the reverse osmosis tank for the treated water in a fluid-conducting manner, wherein the device is designed such that, in a standstill operating state, treated water flows from the pressure vessel through the semipermeable membrane into the first chamber.

[0019] The terms "first" and "second" chamber were chosen here solely to distinguish between the components.

[0020] To adjust the ratio between concentrate flow and permeate flow, the invention particularly employs a throttling device in the concentrate line. The throttling device can be designed simply as an orifice plate, a throttle valve, a throttle valve, or a capillary, or, for example, as a so-called "flow restrictor" that achieves throttling via a Venturi nozzle. In principle, any device that limits the flow rate of the concentrate can be used to adjust the ratio between concentrate flow and permeate flow. Even a pressure tank could be used in the concentrate line, since the increased back pressure also throttles the flow rate. Measuring the conductivity of the permeate and thereby controlling the ratio of the permeate flow to the concentrate flow is also possible, for example, via a control valve.

[0021] To extend the membrane's lifespan and / or improve the system's efficiency, a pressure tank is installed on the permeate side according to the invention. The RO membrane can be backwashed via this pressure tank. There is no connection between the permeate line, which connects to the outlet of the second chamber of the reverse osmosis tank, and the wastewater drain. During backwashing, the water on the concentrate side, i.e., in the first chamber of the reverse osmosis tank, is displaced by permeate, which is transported across the membrane into the concentrate at low pressure. After backwashing, water with a permeate quality of less than 100 µS / cm is available on the concentrate side. The concentration gradient across the semipermeable membrane between the contents of the first and second chambers is virtually zero with the invention.

[0022] Thus, the invention ensures consistently very good water quality with every water withdrawal from the device, regardless of the stagnation time.

[0023] Furthermore, according to the invention, deposits formed by permeate backwashing are repeatedly removed from the semipermeable membrane by so-called "scaling," i.e., the formation of deposits by poorly soluble substances such as CaCO3, SiO2, CaSO4, etc., and / or so-called "fouling," i.e., the contamination of the membrane, especially by microorganisms ("biofouling"). This makes it possible, with the aid of the invention, to operate reverse osmosis continuously with a yield of more than 75%.

[0024] The invention relates primarily to so-called reverse osmosis systems, for example, under-sink reverse osmosis systems, for domestic drinking water. An additional pressure tank can be connected to such a system in case the reverse osmosis unit does not provide sufficient capacity to reliably dispense a sufficient quantity of water when the tap associated with the device is opened. In under-sink reverse osmosis systems, this additional pressure tank is located on the permeate side and is intended to ensure that a sufficiently large quantity of permeate can always be drawn off. A check valve is installed on the membrane side to prevent the membrane from being damaged by the high pressure of the tank (> 2 bar).

[0025] The function of this additional pressure tank is therefore to pump in the exact opposite direction to the pressure tank from which permeate is pumped back through the reverse osmosis system.

[0026] The pressure tank can also be a tank in which a pressurized gas reservoir, for example an air reservoir, is compressed, for example via a membrane or a piston, thus keeping the water under a minimum required pressure.

[0027] In conventional reverse osmosis systems, a backflow preventer ensures that the pressure tank in the permeate line does not empty in the wrong direction. This would also damage the membrane used for reverse osmosis.

[0028] In contrast to such a backflow prevention method, according to the invention, the reverse osmosis process for cleaning the semipermeable membrane or for displacing concentrate from the pressure tank is operated in the opposite direction through the second chamber of the reverse osmosis vessel, so that the concentrate is displaced from the first chamber. For this purpose, the pressure tank is located on the permeate side.

[0029] While conventional reverse osmosis systems often flush the concentrate side with water, in flushing mode pressure is applied to the permeate side, causing the water to flow through the membrane in the opposite direction. This removes contaminants and encrustations, as well as high concentrations of ions on or near the membrane. This significantly extends the membrane's lifespan.

[0030] To limit the pressure exerted on the membrane during backwashing with permeate from the pressure tank, a throttle valve, for example an orifice plate, and in particular a controlled throttle valve, can be arranged between the pressure tank and the reverse osmosis vessel in the permeate line, according to the invention. The throttle valve ensures that the membrane is subjected to sufficiently low pressure of permeate during backwashing.

[0031] Furthermore, the backflow through the semipermeable membrane displaces the water on the concentrate side, reducing its conductivity to a similarly low level as on the opposite side. This means that water with low conductivity is present on the permeate side from the outset.

[0032] Preferred embodiments and further developments of the invention can be found in the subject matter of the dependent claims, the description and the drawings.

[0033] In an advantageous embodiment, the pressure tank has a capacity in the range of approximately 0.1 L to 5 L, preferably the volume of the pressure tank is approximately 1 L. This makes it possible to build the device with dimensions that allow operation in typical households, especially kitchens or bathrooms, as an under-counter installation.

[0034] According to a further advantageous embodiment of the invention, the device is designed for operation without electricity. This means that only water-carrying lines are installed, and operation is purely hydraulic. Preferably, a pressure vessel with a rubber diaphragm is used for this purpose, so the device operates without electricity. The backflushing from the pressure vessel according to the invention occurs due to the pressure built up in the pressure vessel during water withdrawal and thus during the filling of the pressure vessel with permeate, which is therefore particularly higher than the pressure in the second and also in the first chamber of the reverse osmosis vessel.

[0035] The automatic backwashing process thus loosens contaminants and encrustations on the concentrate side of the semipermeable membrane of the reverse osmosis tank and transports them into the wastewater via the concentrate line. Simultaneously, the backwashing of the RO membrane displaces the water remaining on the concentrate side with permeate. According to the invention, both processes are carried out by overpressure on the permeate side.

[0036] To enhance the cleaning effect and for disinfection, a disinfectant, e.g., chlorine, for example as chlorine gas (Cl₂), can be added to the raw water according to the invention. In a further embodiment of the invention, the device includes a chlorine addition unit. This unit is connected to a line for the water to be treated, in particular to the inlet of the first chamber of the reverse osmosis tank for the water to be treated.

[0037] The dosing system can, for example, supply chlorine gas in steel gas cylinders or chlorine drums, whereby the chlorine gas from the respective container is mixed with the raw water via an injector nozzle and at least one metering regulator. The pressure required for injection is generated by a pressure booster pump, which is part of the dosing system. The metering regulator controls the amount of chlorine gas required for the desired disinfection effect of the raw water used, which is determined in advance by a qualified technician.

[0038] However, the addition device can also be designed for other chlorination processes, for example to add sodium hypochlorite or dissolved calcium hypochlorite to the raw water via a dosing pump.

[0039] The chlorine can be removed from the permeate on the permeate side. This improved version is used in countries where chlorination of drinking water is prohibited. This embodiment provides that the device has an absorption unit for the disinfectant, particularly for chlorine, which is connected to a line for the permeate, specifically to the outlet of the second chamber of the reverse osmosis tank for the treated water. In particular, the absorption unit is designed as a carbon block or activated carbon filter.

[0040] This also ensures that the semipermeable membrane is not exposed to disinfectant, such as chlorine, during backwashing. During the so-called stagnation phase, i.e., the standby period, no chlorine or other disinfectant comes into contact with the membrane, as the chlorine or other disinfectant has been removed from the permeate by the absorption unit, and backwashing is therefore carried out with clean permeate. This also increases the membrane's lifespan, since the membrane is only exposed to chlorine or other disinfectant during water withdrawal.

[0041] In an advantageous embodiment of the invention, the reverse osmosis container is designed as a filter cartridge. This makes it possible to construct the device according to the invention in a very compact manner.

[0042] Within the scope of the invention, a corresponding filter cartridge is designed in such a way that the inlet and outlets are integrated into a stationary base unit, and the reverse osmosis tank is provided as an interchangeable unit, which is detachably connected to the base unit. Due to its simple design in conjunction with the interchangeable reverse osmosis tank, such a device for the treatment of drinking water by means of reverse osmosis is particularly suitable for use in private households.

[0043] If the membrane of the replaceable reverse osmosis tank becomes too heavily burdened by fouling and scaling, the entire reverse osmosis system can be easily replaced. Thanks to the modular design of the unit, which uses a filter cartridge as the reverse osmosis tank, the replacement process is remarkably simple. Before initial use, the base unit is installed, for example, permanently integrated into a drinking water line. Subsequent replacements of the reverse osmosis tank do not affect the base unit. Therefore, the replacement can be carried out without difficulty even by non-experts.

[0044] To facilitate easy replacement of the reverse osmosis vessel, the stationary base unit, in preferred embodiments, has a receptacle for the exchangeable unit, preferably a receptacle into which the exchangeable unit can be screwed. Preferably, the receptacle has an internal thread and the exchangeable unit a corresponding external thread. Of course, other technical options for the detachable connection of the base unit and the exchangeable unit are also possible, for example, a snap-fit ​​connection.

[0045] The filter cartridge used for the reverse osmosis tank is preferably one with a wound construction. It preferably comprises a reverse osmosis membrane wound around a perforated tube that serves to collect and discharge the permeate (hereinafter referred to as the permeate collection tube). In preferred embodiments of such reverse osmosis tanks, a membrane pocket, glued or welded on both sides, is connected at its open end to the permeate collection tube and wound around the tube.

[0046] The membrane is particularly preferably in the form of a cylindrical coil having two end faces, hereinafter also referred to as the first and second end faces. Within the container, this coil is preferably arranged such that the first end face points towards the top and the second end face towards the bottom.

[0047] The device for the treatment of drinking water described above can advantageously be used in the context of an under-sink reverse osmosis system for drinking water in households, comprising such a device as well as a raw water line for supplying water to be treated, a withdrawal line for treated water and a wastewater line for removing concentrate.

[0048] This allows for the simple production of drinking water, for example, by installing such an under-sink reverse osmosis system beneath a kitchen worktop, with the water supply for the sink connected to the mains water line and the water drawn off via the corresponding tap. Especially when the reverse osmosis tank of the device is designed as a filter cartridge, the size of an under-sink reverse osmosis system can be significantly reduced compared to conventional systems, which is extremely advantageous for installation under a standard household sink.

[0049] In a preferred embodiment, the under-sink reverse osmosis system has a shut-off valve that connects the raw water line and the dispensing line in such a way that, when the valve is opened, water to be treated is simultaneously fed into the reverse osmosis system and treated water is drawn off. This shut-off valve can be connected to or replace the faucet valve.

[0050] The invention further provides a method for the treatment of drinking water, in particular using a device described above, in which, during a withdrawal phase, drinking water to be treated is pumped through a semipermeable membrane in reverse osmosis mode and separated into permeate and concentrate, with a first portion of the permeate being withdrawn as treated drinking water. During the withdrawal phase, a second portion of the permeate flows into a pressure tank, thereby creating a permeate reservoir in the pressure tank and pressurizing it. In the method according to the invention, during a standby phase, permeate from the pressure tank is pumped through the semipermeable membrane in reverse osmosis mode. This results in backwashing.

[0051] Thus, the invention enables very good water quality with every water withdrawal from the device. This is advantageously independent of how long the water to be treated has been standing in the reverse osmosis tank prior to withdrawal. Furthermore, backwashing repeatedly removes poorly soluble substances such as CaCO3, SiO2, CaSO4, etc., which can accumulate as deposits on the semipermeable membrane.

[0052] In order to minimize mechanical stress on the semipermeable membrane and thus enable a long service life of the membrane, a further development of the inventive method provides that the pressure difference applied to the semipermeable membrane for conveying the permeate through the semipermeable membrane is in the range between 0.05 bar and 1 bar, preferably in the range between 0.1 bar and 0.5 bar, particularly preferably in the range between 0.2 bar and 0.4 bar.

[0053] In a further advantageous embodiment of the method according to the invention, it is carried out such that, on the concentrate side of the semipermeable membrane, the conductivity of the water in the resting state after backwashing has a value of less than 100 µS / cm. Furthermore, within the scope of the invention, the method can be carried out such that the concentration gradient across the semipermeable membrane between the concentrate side and the permeate side is essentially zero in the resting state after backwashing.

[0054] Due to the low concentration gradient between concentrate and permeate achieved with the aid of the invention, correspondingly fewer of the salts, heavy metals, and other pollutants present in the concentrate can diffuse onto the permeate side at rest. This prevents contamination of the permeate at rest.

[0055] The invention is explained in more detail below with reference to the accompanying drawings and exemplary embodiments. Identical and similar components are designated with the same reference numerals, and the features of the different embodiments can be combined. The drawings show: Fig. 1 A schematic representation of a device for treating drinking water with a reverse osmosis tank, which is installed as part of an under-sink reverse osmosis system for drinking water under a kitchen worktop, Fig. 2 a schematic representation of a device for treating drinking water and Fig. 3 A schematic representation of a reverse osmosis container in the form of a filter cartridge for a device for treating drinking water.

[0056] In Fig. Figure 1 shows a reverse osmosis system 1000, which in the example shown is arranged under a kitchen worktop 8 as an under-sink reverse osmosis system 1000 for domestic drinking water. The under-sink reverse osmosis system 1000 comprises a device 10 for treating drinking water with a reverse osmosis tank 2 and a pressure tank 4.

[0057] The under-sink reverse osmosis system 1000 also features a raw water line 1 and a line 3 for treated water. Incoming water is supplied to the unit 10 via the raw water line. During operation, treated water can be drawn from the unit 10 via the outlet line 3.

[0058] Within the scope of the invention, the under-sink reverse osmosis system can additionally include a further pressure accumulator. This can be arranged on the permeate side of the reverse osmosis vessel 2 and protected against it by a backflow preventer. Such an additional pressure tank is pressurized with the pressure that prevails in the line immediately upstream of this additional pressure tank and is positioned upstream of the tap 80. Fig. Figure 2 shows an embodiment of an under-sink reverse osmosis system 1000 in combination with such an additional pressure tank 400. When the tap 80 is opened, the additional pressure tank 400 ensures that permeate can always be drawn off at sufficient pressure via the tap 80.

[0059] The pressure tank 4, which is used for backwashing the semipermeable membrane 11 in the reverse osmosis vessel 2 with permeate, is connected without a backflow preventer and applies lower pressures to the membrane 11 during backwashing – in the range of approximately 0.05 bar to 1 bar – than the line pressure. The backwashing pressure can be adjusted via the throttle valve 32.

[0060] In order to provide sufficient, preferably constant, pressure at the input side regardless of the installation situation, it is also possible to provide, for example, an electrically operated pump in the supply line.

[0061] As shown in the illustration in Fig. As further shown in Figure 1, the reverse osmosis vessel 2 has a first chamber 21 and a second chamber 22. A semipermeable membrane 11 is arranged between the chambers 21 and 22.

[0062] During operation of the device 10 and the under-sink reverse osmosis system 1000 in the draw-off state, the incoming water supplied to the device 10, and thus to the reverse osmosis tank 2, with a conductivity of, for example, 500 µS, is conveyed through the semipermeable membrane 11. In the first chamber 21, dissolved substances in the incoming water are retained, resulting in a concentrate. The concentrate, with a conductivity of, for example, 1000 µS, can be discharged from the device 10 via the concentrate line 6 and discarded via a wastewater line 7.

[0063] During the operation of the device 10 and the under-sink reverse osmosis system 1000, water with a significantly reduced concentration of dissolved substances enters the second chamber 22 as the incoming water passes through the semipermeable membrane 11. This permeate is drawn off as treated water via a line 3. Simultaneously, a pressure tank 4, connected to the permeate line 3 via a line 43, is filled with permeate.

[0064] This ensures that treated, pressurized water is available in pressure tank 4 during dispensing. This is achieved purely hydraulically. Pressure tank 4 has, for example, a capacity in the range of 0.1 L to 5 L, with the volume of pressure tank 4 preferably being approximately 1 L.

[0065] If no water is being drawn, the device 10, and thus the under-sink reverse osmosis system 1000, is in standby mode. This is also referred to as the "standby state." When the pressure is released by the water flowing into chamber 21 and thus onto membrane 11 during water withdrawal, the pressure built up in pressure tank 4 creates pressure from the second chamber 22 onto membrane 11 due to the permeate pumped from pressure tank 4.

[0066] The emptying of the pressure tank 4 after entering the standby state until the pressure difference built up during the withdrawal state between pressure tank 4 and first chamber 21 is equalized causes the automatic backflushing of the semipermeable membrane 11 with the advantages and effects described above.

[0067] Since backflushing from the second chamber 22, which contains permeate after the extraction phase, into the first chamber 21, which contains concentrate, represents an operation of the semipermeable membrane 11 in the direction of osmosis rather than reverse osmosis, low values ​​for the pressure applied by means of the pressure tank 4 are sufficient to enable backflushing.

[0068] In particular, if the device 10 is also equipped with a chlorine addition device (not shown) for disinfection purposes in the case of contaminated raw water, it further comprises an absorption device to remove the chlorine before the purified water is drawn off. For this purpose, an activated carbon block 9 is provided in the illustrated embodiment.

[0069] The under-sink reverse osmosis system 1000 also features a shut-off valve 5, which connects the raw water line 1 and the draw-off line 3 in such a way that when the valve 5 is opened, water to be treated is simultaneously supplied to the reverse osmosis unit and treated water is drawn off. The shut-off valve 5 can be connected to or replace the valve 81 of the tap 80.

[0070] In Fig. Figure 2 shows an under-sink reverse osmosis system 1000, which is operated with an additional pressure tank 400. This additional pressure tank 400 is located on the permeate side, downstream of the under-sink reverse osmosis system 1000 and upstream of the valve 81 of the tap 80. Furthermore, in Fig. Figure 2 shows a pressure booster pump 500 upstream of the raw water inlet 1 to the under-sink reverse osmosis system 100. This can also be used as an alternative to the additional pressure tank 400.

[0071] In an advantageous embodiment of the invention, the entire system is enclosed, so that the under-sink reverse osmosis system 1000, optionally together with a pressure booster pump 500 and / or an additional pressure tank 400 including a backflow preventer 450, is arranged in a housing.

[0072] Fig. Figure 3 shows a schematic cross-sectional representation of a preferred embodiment of a reverse osmosis vessel in the form of a filter cartridge 100. This comprises a stationary base unit 101 and a reverse osmosis unit as a replaceable unit 102. The latter has a plastic housing 103, comprising a base 103a and a top section 103b.

[0073] The housing 103 contains a reverse osmosis membrane in the form of a cylindrical coil 104, which has a first end face 104a and a second end face 104b. The permeate collection tube 105 is located in the center of the coil. The coil 104 is connected to the head section 103b via the adapter 106. The adapter 106 provides inlets and outlets for incoming water and for outgoing permeate and concentrate, namely the inlet opening 107, the outlet opening 108, and the outlet opening 109. Furthermore, the adapter provides the inlet channel 107a and the outlet channels 108a and 109a, of which channel 108a connects the outlet opening 108 to the permeate collection tube 105, while the concentrate is fed to the outlet opening 109 via the outlet channel 109a.

[0074] The base unit 101 is connected to the interchangeable unit 102 by means of a screw connection. For this purpose, the base unit 101 has an internal thread 110, and the interchangeable unit 103 has an external thread 111. Seals 112 and 114 are positioned between the base unit 101 and the interchangeable unit 102 in the area of ​​the outlet openings 108 and 109. A further seal 113 is located in the area of ​​the threads 110 and 111, respectively.

[0075] The base unit 101 comprises an inlet 115 for saline water to be treated in the exchange unit 102, an outlet 116 for permeate formed in the exchange unit, and an outlet 117 for concentrate formed in the exchange unit 102. When the exchange unit 102 is screwed into the base unit 101, as shown, the inlet 115 is coupled to the inlet opening 107, the outlet 116 to the outlet opening 108, and the outlet 117 to the outlet opening 109.

[0076] The base unit 101 can further include the blending devices 118 and / or 123, and optionally the control device 119. The blending device 118 mixes permeate exiting the reverse osmosis unit 102 with saline water entering the base unit 101 via the inlet 115. The blending device 123 mixes permeate exiting the reverse osmosis unit 102 with concentrate. The control device 119 regulates the flow rate of the concentrate exiting the reverse osmosis unit 102 and thus indirectly controls permeate formation in the reverse osmosis unit 102.

[0077] The flow direction of the water to be treated, or of the resulting permeate and concentrate, within the device 100 is illustrated by arrows. During operation, saline water enters the base unit 101 via the inlet 115. From there, the water is fed into the exchange unit 102 of the reverse osmosis tank, in the form of a filter cartridge, via the inlet opening 107. Within this unit, it flows through the inlet channel 107a and through a gap between the outer shell 121 of the cylindrical coil 104 and the inner wall 122 of the pressure vessel to the second end face 104b, and then flows axially through the coil towards the first end face 104a, resulting in the formation of permeate and concentrate.

[0078] While the permeate is discharged via the permeate collecting tube 105, the concentrate emerges from the first end face 104a of the cylindrical winding 104. Permeate from the permeate collecting tube 105 can flow upwards through the channel 108a and via the outlet opening 108 into the base unit 101. Here, it enters an annular cavity 120, which is enclosed by the base unit 101 and the exchange unit 102. From there, it is fed to the outlet 116. Concentrate emerging from the first end face 104a of the cylindrical winding 104 flows via the outlet channel 109a to the outlet opening 109 and enters the base unit 101. There, it is fed to the outlet 117. The amount of concentrate exiting outlet 117 can be regulated by means of the control device 119, which is usually a valve. Reference symbol list 1 line for incoming water, raw water, water to be treated, feed 2 reverse osmosis tanks 21 First chamber of the reverse osmosis tank 22 second chamber of the reverse osmosis tank 100 reverse osmosis containers in the form of a filter cartridge 101 permanently installed base units 102 Reverse osmosis unit as a replaceable unit 103 cases 103a Bottom of the case 103b Head of the housing 104 wraps 104a first end face of the coil 104b second end face of the wrap 105 Permeate collecting pipe 106 adapters 107 Inlet opening for incoming water 107a Inlet channel for incoming water 108 Outlet opening for escaping permeate 108a Outlet channel for exiting permeate 109 Outlet opening for escaping concentrate 109a Outlet channel for escaping concentrate 110 internal threads 111 External threads 112 Seal 113 Seal 114 Seal 115 Inlet for saline water to be treated 116 Outlet for formed permeate 117 Outlet for formed concentrate 118 Blending device 123 Blending device 119 Control device 121 Coat 122 Interior wall 3 Permeate line, line for treated water 32 Throttle valve, orifice, in particular regulated throttle valve 4 Pressure tank, pressure vessel 43 Pipe between pressure tank and permeate line, pipe between pressure tank and outlet for the treated water 5 shut-off valve 6 Concentrate line 7 Wastewater pipe 8 Kitchen worktop, table 80 faucet 81 Valve of the tap 9. Absorption device, especially for disinfectants, for example for chlorine; e.g. activated carbon block 10 Device for treating drinking water 11 semipermeable membrane 1000 Under-sink reverse osmosis system 400 additional pressure tank on the permeate side 450 Check valve 500 pump for pumping the raw water in the supply line

Claims

[1] Methods for the treatment of drinking water, in which drinking water to be treated in the extraction operating state Reverse osmosis operation is carried out through a semipermeable membrane (11) and separated into permeate and concentrate, characterized by , that During the extraction state, a portion of the permeate flows into a pressure tank (4), thereby creating a permeate reserve in the pressure tank (4) and pressurizing it, and during the standby state, a portion of the permeate passes through the membrane (11) by means of the overpressure, thereby displacing the concentrate on the concentrate side of the membrane (11) and possibly removing any deposits present on the concentrate side of the membrane (11). [2] Method for the treatment of drinking water according to claim 1, characterized by, that the pressure difference which is applied to the semipermeable membrane (11) for conveying the permeate through the semipermeable membrane (11) is in the range between 0.05 bar and 1 bar, preferably in the range between 0.1 bar and 0.5 bar, particularly preferably in the range between 0.2 bar and 0.4 bar. [3] Method for the treatment of drinking water according to claim 1 or claim 2, characterized by , that the procedure is carried out in such a way that, on the concentrate side of the semipermeable membrane (11) in the resting state after backwashing, the conductivity of the water has a value of less than 100 µS / cm. [4] Method for the treatment of drinking water according to any one of the preceding claims 1 to 3, characterized by , that the incoming water is disinfected with a disinfectant only during withdrawal operation, but not during standby mode. [5] Device (10) for treating drinking water, configured for a method according to one of claims 1 to 4, with at least one reverse osmosis tank (2; 100), which is divided into at least two chambers (21, 22) by at least one semipermeable membrane (11), wherein the first chamber (21) has an inlet for the water to be treated and an outlet for the concentrate and the second chamber (22) has an outlet for the treated water, which transfers the treated water into a withdrawal line (3), characterized by , that the device (10) comprises at least one pressure vessel (4) which is connected via a line (43) which is connected to the extraction line (3) only to the outlet for the treated water, and has a throttle valve (32), for example an orifice, in particular a controlled throttle valve, which is arranged between the pressure vessel (4) and the reverse osmosis vessel (2), wherein the device (10) is designed such that, in the standby operating state, treated water is drawn from the pressure vessel (4) through the semipermeable membrane (11) flows back into the first chamber (21). [6] Device (10) for treating drinking water according to claim 5, characterized by , that the pressure vessel (4) has a capacity of 0.1 L to 5 L, preferably the volume of the pressure vessel (4) being approximately 1 L. [7] Device (10) for treating drinking water according to claim 5 or claim 6, characterized by , that the device (10) is designed for operation without electricity. [8] Device (10) for treating drinking water according to one of claims 5 to 7, characterized by, that the device (10) has an addition device for a disinfectant which is connected to a line for the water to be treated, in particular to the inlet of the first chamber of the reverse osmosis container (2; 100) for the water to be treated. [9] Device (10) for treating drinking water according to claim 8, characterized by , that the device (10) has an absorption device (9), in particular for a disinfectant, for example chlorine, which is connected to a line (3) for the permeate, in particular to the outlet of the second chamber (22) of the reverse osmosis container (2; 100) for the treated water. [10] Device (10) for treating drinking water according to one of claims 5 to 9, characterized by , that the reverse osmosis container (100) is designed as a filter cartridge. [11] Reverse osmosis system (1000) for drinking water in households, comprising a device (10) according to one of claims 5 to 10 as well as a raw water line (1) for supplying water to be treated, a withdrawal line (3) for treated water and a wastewater line (6; 7) for removing concentrate. [12] Reverse osmosis system (1000) for drinking water according to claim 11, characterized by , that the reverse osmosis system (1000) has a shut-off valve (5) which couples the raw water line (1) and the extraction line (3) in such a way that when the valve (5) is opened, water to be treated is simultaneously supplied to the reverse osmosis system and treated water is extracted.

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