Apparatus and method for producing permeates, in particular for dialysis treatments

Abstract

The invention relates to a water treatment device for producing a permeate, in particular for dialysis treatments, comprising: a reverse osmosis stage having a line system comprising an input line for process input water, a reverse osmosis pump and a reverse osmosis container, wherein the reverse osmosis vessel has an inlet for process input water from a reverse osmosis pump, a membrane and an outlet for permeate; the invention relates to a reverse osmosis system comprising a reverse osmosis stage, a reverse osmosis stage, a reverse osmosis stage, a reverse osmosis stage, a reverse osmosis stage, a reverse osmosis stage, a reverse osmosis stage, a reverse osmosis stage, a reverse osmosis stage, a reverse osmosis stage, a reverse osmosis stage, a reverse osmosis stage, a reverse osmosis stage, a reverse osmosis stage, a reverse osmosis stage, a reverse osmosis stage, a reverse osmosis stage and a reverse osmosis stage, the reverse osmosis stage supplies permeate to the permeate stage, and wherein the loop of the permeate stage comprises a sterile filter.

Description

TECHNICAL FIELD

[0001] The invention relates to a water treatment device for producing a permeate, wherein the application in dialysis therapy is focused on. The invention also relates to a method of the kind. BACKGROUND

[0002] The state of the art comprises different methods for carrying out water treatment, in particular such methods based on the principle of reverse osmosis. These methods are widely used in particular in dialysis applications in order to produce a high-purity water and thus a high-quality permeate. However, the existing systems can have challenges in terms of efficiency, control and quality optimization.

[0003] Especially for so-called single-station devices which are often directly erected at the point of treatment for dialysis, a relatively high energy requirement is produced by the continuous operation of the pump required for reverse osmosis. The noise disturbance for the patient can also be noticeable. SUMMARY

[0004] It is the task of the invention to propose a water treatment device of the kind mentioned, which produces a high-purity permeate in an energy-efficient and low-noise and at the same time as reliable as possible manner. Furthermore, a method of the kind for producing a permeate is to be mentioned.

[0005] According to the invention, the task mentioned is solved in terms of the device by a water treatment device for producing a permeate, in particular for dialysis therapy, comprising

[0006] • a reverse osmosis stage with a pipe system, which comprises an input pipe for process input water, a reverse osmosis pump and a reverse osmosis vessel (also referred to as pressure tube), wherein the reverse osmosis vessel has an inlet for the process input water from the reverse osmosis pump, a membrane and an outlet for the permeate,

[0007] • a permeate stage with a pipe system forming a circuit, which comprises a permeate tank, a permeate pump and an access point for connecting at least one consumer or access of the permeate,

[0008] wherein the reverse osmosis stage and the permeate stage are connected to each other by a connecting pipe in such a way that the reverse osmosis stage supplies the permeate stage with the permeate, and wherein the circuit of the permeate stage comprises a sterile filter

[0009] The concept of "stage" is preferably understood here in the meaning of "unit" or "device" in general and does not exclude that the reverse osmosis stage itself can also be configured in multiple stages.

[0010] The object of the application is thus to feed the permeate produced in the reverse osmosis stage to a permeate tank for intermediate storage, from which the permeate can be kept in circulation with comparatively little energy expenditure by means of a separate permeate pump. The reverse osmosis pump in the reverse osmosis stage, which has a greater energy requirement than the permeate pump, can then be switched off for longer periods of time until a batch of permeate has to be produced again after corresponding withdrawal by the consumer.

[0011] In other words: the water treatment device automatically adapts to the demand by controlling (switching on and off) the reverse osmosis pump depending on the filling level in the permeate tank. This facilitates efficient use of resources and adaptation of the operation to the actual requirements. The main low-noise properties of the device are thereby also ensured, which increases the comfort and well-being of the patient.

[0012] According to the application, the circuit of the permeate stage also comprises a sterile filter, which is preferably arranged downstream of the permeate pump and upstream of the permeate tank. The integration of the sterile filter in the circuit of the permeate stage ensures additional safety and purity of the produced permeate by separating or retaining microorganisms that can be present in the permeate circuit.

[0013] Advantageous design options are the subject of the dependent claims and the following detailed description.

[0014] Furthermore, it is preferred that the withdrawal point for a consumer, which can be connected by means of a hose connection, for example, is arranged downstream of the sterile filter and upstream of the permeate tank, wherein advantageously an overflow valve or a flow restrictor is arranged between the withdrawal point and the permeate tank in order to ensure the desired or necessary pressure at the withdrawal point.

[0015] There is preferably a device control device which switches on and off the reverse osmosis pump depending on the filling level in the permeate tank. As already mentioned, the reverse osmosis pump is only operated when there is a real demand for it.

[0016] In order to realize such a demand-based control, there can be a pressure-based filling level detection device for the permeate tank, wherein, for example, the hydrostatic pressure of the permeate column in the permeate tank is measured and the filling level height or the filling quantity is determined therefrom.

[0017] In a possible variant, the permeate pump is pressure-regulated in accordance with the pressure in the circuit of the permeation stage. This means that the pump power or the rotational speed of the permeate pump is automatically matched to or regulated in such a way that a predefined target pressure is achieved and maintained. This pressure-regulating function enables precise control of the permeate throughput by modeling the permeate pump in accordance with the pressure in the system. This not only improves process stability, but also helps to avoid undesirable pressure fluctuations. However, the main aim is to save electrical energy and reduce noise emissions, since the rotational speed of the permeate pump can be reduced when no permeate is being taken off.

[0018] In this variant, it is advantageous for the pressure sensor for regulation to be arranged in the circuit between the take-off point and a flow restrictor, which is arranged upstream of the permeate reservoir.

[0019] In an alternative variant, the permeate pump is volume-flow-regulated in accordance with the throughput through the circuit of the permeation stage. A permeate pump that is volume-flow-regulated enables precise adaptation of the pump rotational speed, with the aim of stabilizing the throughput in the circuit. This is particularly advantageous in order to match the permeate flow to the requirements of the consumer or take-off point and to ensure optimum utilization of the permeate produced. However, it is also important here to save electrical energy.

[0020] In this variant, it is advantageous for the volume-flow sensor for regulation to be arranged in the circuit between the take-off point and a pressure relief valve, which is arranged upstream of the permeate reservoir.

[0021] In a possible embodiment, the permeate reservoir is additionally configured as a pressure expansion vessel. This guarantees precise pressure control in the system. The pressure expansion vessel firstly serves as a buffer for the permeate, whereby the connected dialysis apparatus is not idling. Furthermore, this helps to minimize undesirable pressure fluctuations and to increase the service life of the components.

[0022] In a preferred design, the connecting line between the reverse osmosis stage and the permeation stage is designed in such a way that the entire permeate production of the reverse osmosis stage is fed into the circuit of the permeation stage. That is to say, the reverse osmosis stage preferably has no take-off point of its own, but the taking off of the permeate is only achieved via the circuit of the permeation stage.

[0023] In a possible refinement, the reverse osmosis stage has a heater for the process input water, which works according to the principle of a continuous heater, which is preferably arranged between the reverse osmosis pump and the reverse osmosis vessel. By this means, the water can be heated for the purpose of achieving thermal decontamination or thermal sterilization of all the pipe sections downstream of the reverse osmosis stage and the permeation stage, which are connected in terms of flow.

[0024] If the reverse osmosis stage has a recirculation line for concentrate trapped by the membrane, this is primarily used to increase the efficiency with regard to water consumption, since water can also be fed again into the filtration process. Furthermore, premature clogging of the membrane is avoided. The reinjection of concentrate from the recirculation line into the main line from the reverse osmosis pump to the reverse osmosis vessel can be effected, for example, by means of a Venturi nozzle.

[0025] In another advantageous design variant, the reverse osmosis stage has a receiving tank for the intermediate storage of process input water. The integration of the receiving tank in the reverse osmosis stage makes it possible to implement the intermediate storage of process input water. This is particularly advantageous in order to compensate for fluctuations in the water demand or in the inlet and to ensure at least temporarily a continuous permeate yield.

[0026] The reverse osmosis stage and the permeate stage can be structurally separated and erected at different locations, for example in the case of correspondingly long connecting lines, but they can also be integrated structurally in one compact device, for example a single-station reverse osmosis device which is erected directly next to the dialysis location. It can also be advantageous for specific applications to separate the two units in the housing in order to reduce the noise and / or to provide a modular solution which can be loaded individually more flexibly than an entire device installed in one housing. In general, it is advantageous to keep the lines between the reverse osmosis device and the dialysis apparatus as few / short as possible in order to reduce the amount of standing water to a minimum.

[0027] Furthermore, the application provides a method for producing a permeate, in particular for a dialysis treatment. For this purpose, a water treatment device of the type described above is preferably used. The method is distinguished in that the permeate is produced according to the reverse osmosis principle in that process input water is pressed through a membrane by means of a reverse osmosis pump, the permeate produced is then fed, preferably completely, into a permeate tank and is circulated in a circuit connected to the permeate tank by means of a permeate pump, wherein possible users or consumers of the permeate can be connected to the circuit, and wherein the permeate is guided through a sterile filter in the circuit.

[0028] It is advantageous if the reverse osmosis pump is switched off if the filling level of the permeate in the permeate tank exceeds a defined value, and if the reverse osmosis pump is switched on again only if the filling level of the permeate in the permeate tank is below a defined value.

[0029] The tasks, features, variants and advantages mentioned for the device apply to the method in the sense and vice versa. BRIEF DESCRIPTION OF DRAWINGS

[0030] The different embodiments of the application are explained in detail below with reference to the drawings. In which:

[0031] Figure 1 A simplified hydraulic principle circuit diagram of a reverse osmosis apparatus for producing a dialysate for a hemodialysis treatment according to the state of the art (prior art) is shown,

[0032] Figure 2 A water treatment apparatus for producing a dialysate for a hemodialysis treatment according to the application is shown, wherein the apparatus is preferably designed as a single-station apparatus, and wherein the apparatus is equipped with a reverse osmosis stage and a permeate stage with a separate permeate tank,

[0033] Figure 3 A water treatment apparatus of the type shown in Figure 2 with a permeate pump regulated by volume flow,

[0034] Figure 4 A water treatment apparatus of the type shown in Figure 2 with a permeate pump regulated by pressure,

[0035] Figure 5 A water treatment apparatus of the type shown in Figure 2 with an additional receiving tank in the reverse osmosis stage,

[0036] Figure 6 A water treatment apparatus of the type shown in Figure 2 with an additional thermal purification option,

[0037] Figure 7 A water treatment apparatus of the type shown in Figure 6 with a recirculation option for the permeate, Figure 6

[0038] Figure 8 A water treatment apparatus of the type shown in Figure 2 with a pressure expansion vessel in the permeate stage, and

[0039] Figure 9 A water treatment apparatus of the type shown in Figure 2 with a Venturi nozzle for concentrate-recirculation in the reverse osmosis stage.

[0040] The same or identically acting elements are provided with the same reference numerals in all the figures. DETAILED DESCRIPTION

[0041] Figure 1 An overview of a reverse osmosis apparatus 111 for producing a dialysate for a hemodialysis treatment according to the state of the art is shown in the form of a hydraulic diagram. ​

[0042] The main components of the reverse osmosis device 111 are a receiving tank 102 for the process input water 100 and a reverse osmosis vessel 130 with a semi-permeable membrane 104 (reverse osmosis membrane) which are combined into a hydraulic circuit by means of a pipe system. An input line 131 for the process input water 100 (also referred to as soft water) is connected to the receiving tank 102. The delivery of the process input water 100 into the receiving tank 102 can be controlled by means of a solenoid valve 101 or a similar device which is connected into the input line 131. The receiving tank 102 and the reverse osmosis vessel 130 are connected to each other by means of a connecting line 132 in such a way that the process input water 100 is delivered from the receiving tank 102 into the reverse osmosis vessel 130 by means of a reverse osmosis pump 103 which is connected into the connecting line 132 in operation and is pressed through the membrane 104 there. Thus, water enters into the reverse osmosis vessel 130, which is also referred to in the professional field as "pressure tube" or "Membrane Pressure Vessel", through an inlet 143, the water then traverses the membrane 104 and is discharged from the reverse osmosis vessel 130 through an outlet 144. In this process, impurities contained in the process input water 100, mainly in the form of ions, are retained on the concentrate side (dirt side) of the reverse osmosis vessel 130, i.e. upstream of the membrane 104, in accordance with the reverse osmosis principle. In concentrated form, the impurities are also referred to as concentrate 105.

[0043] The purified water, or simply permeate 108, which is discharged from the membrane 104 on the permeate side (pure side) is delivered to a number of consumers or users by means of a ring line 133, which can be connected to the ring line 133 at the user sites 134 by means of junctions 109, respectively. The permeate 108 which is not consumed or not used is circulated back into the receiving tank 102 by means of the ring line 133. An overflow valve 110 which is connected into the ring line 133 downstream of the junctions 109 opens when a set holding pressure is reached or exceeded and thus ensures a minimum pressure at the user sites 134.

[0044] In a preferred case, the reverse osmosis vessel 130 can be a pressure tube into which the membrane 104 is inserted. Such a pressure tube preferably has an opening for the insertion and replacement of the membrane module, which pressure tube is distinguished from a simple tube. The pressure tube is also generally larger (in terms of diameter) than the conventional pipe cross section due to the membrane geometry.

[0045] Furthermore, a recirculation of at least a portion of the concentrate 105 on the concentrate side of the circuit can be provided. For this purpose, a (concentrate) recirculation line 135 is connected to the concentrate side of the reverse osmosis vessel 130, which recirculation line flows into the connection line 132 at the other end upstream of the reverse osmosis pump 103. A needle valve 107 or similar device (flow restrictor) connected into the recirculation line 135, which is preferably adjustable in terms of flow, limits the recirculation and prevents a fluid-technical short circuit. The attachment of the concentrate 105 at the membrane 104 is prevented or at least delayed by the recirculation. However, the attachment or entanglement of the membrane is primarily prevented more easily by the fact that water is passed, in particular, next to the membrane. Here, it can be directed into the connection line or into the drain 136.

[0046] Furthermore, a drain line, or simply drain 136 (or "waste section"), branches off from the recirculation line 135, wherein the drain 136 is closed by a controllable solenoid valve 106 in the normal operation of the reverse osmosis device 111. By opening of the solenoid valve 106, the concentrate 105 can be discarded from the reverse osmosis vessel 130 or the reverse osmosis circuit, if necessary. When discarding the concentrate, which has a high number of ions compared to the process input water, the missing volume is replaced by process input water from the receiving tank 102, which has a low number of ions. Thereby, the total number of ions of the process water in the circuit decreases.

[0047] A disadvantage of such a system is the high energy consumption due to the continuous reverse osmosis. Furthermore, the noise disturbance for the user caused by the continuously operating reverse osmosis pump 103 is also mentioned. This is particularly important for single-station reverse osmosis devices, since these are mostly placed in the vicinity of the patient.

[0048] In order to avoid such problems, in Figure 2 The water treatment device, which is generally referred to as reverse osmosis device 111, is composed of two sub-units. The first sub-unit, which can also be referred to as reverse osmosis stage 137 or reverse osmosis unit or RO stage (RO = Revers Osmosis = English for reverse osmosis), obtains the process input water 100 via the input line 131, into which the solenoid valve 101 is connected. Downstream of the solenoid valve 101, the input line 131 transitions into the known connection line 132, which is connected to the reverse osmosis vessel 130 at the other end. In accordance with the known prior art, the connection line 132 is connected to the reverse osmosis vessel 130 at the other end. Figure 1 The known connection line 132 is connected to the reverse osmosis vessel 130 at the other end. In accordance with the known prior art, the connection line 132 is connected to the reverse osmosis vessel 130 at the other end. Figure 1The device differs from the prior art in that here a receiving tank 102 for the intermediate storage of the process input water 100 is not necessarily provided, although it can be present in modified variants (see below). A reverse osmosis pump 103 is incorporated into the connecting line 132. The process input water 100 is thus pumped by the reverse osmosis pump 103 into a reverse osmosis vessel 130 having a membrane 104 and is pressed through the membrane. Here, according to the principle of reverse osmosis, the impurities contained in the process input water 100, mainly in ionic form, are retained on the concentrate side (dirt side) of the reverse osmosis vessel 130.

[0049] Like the prior art, the reverse osmosis stage 137 can have a recirculation line 135 for recirculation of the concentrate 105 and a discharge 136 for tapping or discharging the concentrate 105. The corresponding explanations of the prior art thus also apply here. Figure 1 Figure 2 The water with the retained impurities (concentrate 105) on the concentrate side of the reverse osmosis vessel 130 is thus either discarded through the discharge 136 with the then open electromagnetic valve 106 according to the operating mode, or is guided through the recirculation line 135 with the needle valve 107 to the suction side of the reverse osmosis pump 103 in order to be fed back into the process there when the electromagnetic valve 106 is closed.

[0050] In normal operation when the reverse osmosis pump 103 is running, the purified water, or simply permeate 108, which is discharged from the membrane 104 on the permeate side (pure side), is guided through a connecting line 138 into a permeate tank 112, which is a component of a second subunit also referred to as permeate stage 139 or permeation unit. This process is carried out until a desired maximum filling level of the permeate 108 in the permeate tank 112 is reached, which is monitored in a sensoric manner. For example, the permeate tank 112 is signaled to be sufficiently filled by means of a pressure sensor 113 which is hydraulically connected to the bottom of the permeate tank 112. The filling level in the permeate tank 112 is here calculated by the measured hydrostatic pressure of the permeate column and the known tank geometry by a device control 150 or control unit, which is here shown purely schematically. After the maximum filling level in the permeate tank 112 has been reached, the reverse osmosis pump 103 in the reverse osmosis stage 137 is switched off by the device control 150 until the permeate level in the permeate tank 112 falls below a pre-set minimum filling level, which is monitored in a sensoric manner. This monitoring can likewise be achieved by means of the pressure sensor 113. In other words, the reverse osmosis pump 103 is operated, i.e. switched on and off, such that the permeate level in the permeate tank 112 is kept within a predefined range.

[0051] ​As an alternative / additional solution, the measurement of the filling level height in the permeate tank 112 can also be carried out by other common sensors and measuring methods.

[0052] In order to avoid germ formation, the permeate 108 in the permeate stage 139 is kept in motion continuously during the operation of the apparatus in such a way that the permeate is circulated in a circuit by means of the permeate pump 114. For this purpose, a (permeate) circulation line 140, also called ring or circular line, is preferably connected to the bottom of the permeate tank 112 and merges into the permeate tank 112 at the other end, for example at the upper side of the permeate tank 112. The permeate pump 114, the sterile filter 116 and the overflow valve 110 are advantageously connected into the circulation line 140 in this order (seen in the flow direction). The sterile filter 116 is preferably a particle filter. It should separate or rather retain microorganisms which can be present in the permeate circuit. Usually, the sterile filter has a pore size of 0.2 μιη. The permeate pump 114 drives the permeate 108 through the circuit, in the sterile filter 116 impurities which remain or impurities which are in the production phase or germs are retained, and the overflow valve 110 ensures a preliminary pressure control in the circuit in such a way that it opens (only) above a preset response pressure.

[0053] Between the sterile filter 116 and the overflow valve 110 at least one access point 134 is connected, which has an adapter 109 for connecting a consumer or an access to the circulation line 140.

[0054] After the permeate tank 112 is sufficiently filled with permeate 108, the permeate pump 114 is started and the permeate 108 is circulated through the sterile filter 116 and the overflow valve 110 back into the permeate tank 112. The overflow valve 110 serves to maintain the desired pressure at the access point 134. The dialysis apparatus in question is connected on the adapter 109 and takes up the permeate 108 when required. As soon as the level of the permeate 108 in the permeate tank 112 falls below a defined level, the production of permeate in the reverse osmosis stage 137 is started again by switching on the reverse osmosis pump 103 and opening the electromagnetic valve 101 on the input side.

[0055] Between the permeate pump 114 and the sterile filter 116, an outlet line 141, which is closed in normal operation by an electromagnetic valve 115, branches off from the permeate circulation line 140. At the end of the permeate supply, the electromagnetic valve 115 is opened and the remaining permeate 108 is discarded or rather the permeate side is flushed. Here, it is preferred not to lead all the permeate 108 out of the permeate tank 112, but only to reduce it to a predefined minimum in order to have as little standing water as possible in the apparatus.

[0056] The permeate tank 112 advantageously has a tank ventilation with an air filter (not shown in the drawing) so that no overpressure or underpressure occurs due to level changes. As an additional option, flushing can be carried out with a minimum amount during the standby phase.

[0057] Since the flow resistance of the sterile filter 116 is significantly smaller than the flow resistance of the membrane 104 in the device according to Figure 1 , the permeate pump 114 can be designed significantly smaller in terms of its pumping power than the reverse osmosis pump 103, wherein energy is saved accordingly and the noise disturbance is less when the reverse osmosis pump 103 is paused. By the continuous low-energy recirculation of the permeate 108 in the permeate stage 139, germs formation is often reduced to a minimum. The system can be realized with relatively few components, especially as a single-station device, with a saving in space.

[0058] Variants without sterile filter or with alternative filtration unit

[0059] In a possible variant, the sterile filter 116 is completely dispensed with. Instead of the sterile filter 116, other filter units or, for example, a germicidal UV illumination device for the flowing permeate 108 and / or a sterilizing and / or disinfecting heating device, which is switched off during the dialysis operation, can also be provided. Such measures can be arbitrarily combined.

[0060] Variants with permeate pump regulated by volumetric flow

[0061] In the basic version according to Figure 2 , the permeate pump 114 is not regulated, i.e. is equipped with a pure on / off control. In Figure 3 , a variant with a permeate pump 114 regulated in terms of volume flow is shown. Here, the (not shown) control unit regulates the rotational speed of the permeate pump 114 to a level such that a predetermined and preferably adjustable flow or volume flow of the permeate 108 is measured at the volume flow sensor 117 or adhered to. The volume flow sensor 117 is preferably connected into the permeate circulation line 140 between the access point 134 with the connector 109 and the overflow valve 110 and thereby measures the backflow of the permeate 108 per time and volume unit into the permeate tank 112. By this measure, the rotational speed of the permeate pump 114 can first be reduced in phases in which the connected dialysis instrument does not access the permeate.

[0062] Variants with permeate pump regulated by pressure

[0063] In Figure 4A variation of the permeate pump 114 with pressure regulation is shown. The control unit here regulates the rotational speed of the permeate pump 114 to a level such that a predetermined, preferably adjustable, pressure is measured at the pressure sensor 118. The overflow valve 110 in the previously described variation is replaced by a flow limiter 119 to enable the regulation principle. The pressure sensor 118 is preferably coupled to the permeate circulation line 140 between the access point 134 and the flow limiter 119.

[0064] Variants with receiving tank

[0065] As in Figure 5 As shown, the reverse osmosis stage 137 can be extended with a receiving tank 102 in a manner similar to that of the prior art. That is, the process input water 100 first flows into the receiving tank 102, which functions as an intermediate storage tank, via the input line 131 with a solenoid valve 101, and from there continues to flow to the reverse osmosis vessel 130 via the connecting line 132. This has the advantage of compensating for low pressure of the process input water 100, for example, in cases of poor water supply. Thus, dry operation of the permeate tank 112 or the dialysis apparatus connected to the dispensing point 134 can be avoided. The quantity control (or fill height control) of the process input water 100 in the receiving tank 102 is preferably performed here by a pressure sensor 120, which measures the hydrostatic pressure of the water column in the receiving tank 102, similar to the fill height control described above in the permeate tank 112.

[0066] Variants with heater

[0067] In order to perform heat sterilization on the entire equipment, as... Figure 6 The heater 121, which is particularly in the form of an electric heating unit, is installed in the equipment. The heater 121 is preferably connected to a connecting line 132 between the reverse osmosis pump 103 and the reverse osmosis vessel 130. Additionally, a solenoid valve 123 is installed in a connecting line 138 between the reverse osmosis vessel 130 and the permeate storage tank 112 to allow for the interruption of the permeate volumetric flow rate from the reverse osmosis stage 137 to the permeate stage 139 as needed.

[0068] During heat sterilization, the solenoid valve 123 is first closed and the heater 121 is started. Temperature and heating characteristics can be monitored by a temperature sensor 122, preferably coupled upstream of the reverse osmosis pump 103 to the connecting pipe 132, which measures the temperature of the process input water 100 flowing there. Furthermore, an additional temperature sensor can be installed in the permeate circuit to measure the sterilization temperature in the permeate circuit.

[0069] Once the water has been heated accordingly and leaves the reverse osmosis vessel 130 in the form of permeate 108, the solenoid valve 123 is opened in order to deliver the water into the permeate stage 139. As an alternative, the solenoid valve 123 can be opened intermittently in order to keep the temperature change rate at a low level, in that cooler process input water 100 is supplemented in admixture.

[0070] In the permeate stage 139, the heated water is circulated accordingly and monitored by means of a temperature sensor 124, which is coupled to the permeate-circulation line 140 preferably between the take-off point 134 and the overflow valve 110 (as an alternative to the flow restrictor 119).

[0071] After the heat sterilization, cooling is effected by discarding the hot water through the outlet controlled by means of the solenoid valves 106 and 115. The water discarded is replaced by cooler process input water 100.

[0072] The sterilization of the stages (reverse osmosis stage 137 and permeate stage 139) is preferably effected in parallel, but can also be effected sequentially. In the latter case, however, the sterilization process is then initially only partially effected in the reverse osmosis stage, since initially no flow is effected on the permeate side.

[0073] Variants with permeate circulation

[0074] In Figure 7 a device based on a variant according to Figure 6 In this device, the permeate 108 heated for sterilization by means of the heater 121 can be directed from the permeate circuit in the permeate stage 139 back into the reverse osmosis stage 137 via a return line 142 (when the solenoid valve 125 is open). For this purpose, the return line 142 with the solenoid valve 125 is branched off from the permeate-circulation line 140 preferably between the take-off point 134 and the overflow valve 110 (as an alternative to the flow restrictor 119) and merges into the connection line 132 upstream of the reverse osmosis pump 103 in parallel with the input line 131. This has the advantage that the heat sterilization can be performed more uniformly in the system. It is also possible to flush the reverse osmosis stage 137 in standby operation without having to obtain new process input water 100 through the input line 131 with the solenoid valve 101.

[0075] The return of the permeate 108 from the permeate stage 139 into the reverse osmosis stage 138 is provided only in the heat sterilization operation. As in all other variants described, in the regular operation, regularly temperature-adjusted permeate 108 is provided at the take-off point 134, advantageously without the return of the permeate 108 from the permeate stage 139 into the reverse osmosis stage 137.

[0076] Variants with pressure expansion vessel

[0077] exist Figure 8 Based on Figure 2 A variant of the basic version features a device that replaces the conventional permeate storage tank 112 with a pressure expansion vessel 126, also known as a pressure balancing vessel. This pressure expansion vessel is filled with permeate 108 from the reverse osmosis stage 137 until the pressure sensor 113, coupled to the outlet of the pressure expansion vessel 126, exceeds a preset threshold. A check valve 127 in the connecting line 138 between the reverse osmosis stage 137 and the permeate stage 139 prevents the pressure expansion vessel 126 from pushing the permeate 108 back into the membrane 104. A check valve 128 in the permeate circulation line 140, preferably in the section between the overflow valve 110 (or alternatively, the flow limiter 119) and the pressure expansion vessel 126, prevents reverse volumetric flow during the operation phase when the reverse osmosis pump 103 is turned on, or through the action of the pressure expansion vessel 126.

[0078] Variants with venturi nozzle

[0079] exist Figure 9 Based on Figure 2 A variant of the basic version shows a device that utilizes a Venturi nozzle 129 connected downstream of the reverse osmosis pump 103 to a connecting line 132 to recirculate the concentrate 105 in the reverse osmosis stage 137. The Venturi nozzle 129 replaces the... Figure 2 The preferred embodiment of the needle valve 107 operates as follows: a drive jet of process input water 100 in connection line 132 is drawn in from recirculation line 135 and entrains concentrate fed into the narrow orifice of Venturi nozzle 129. Venturi nozzle 129 can have an adjustable nozzle seat to regulate volumetric flow rate. The Venturi variant is a form of energy recovery because pressure is not lost through the needle valve as is customary, but is instead fed back directly through the Venturi effect on the pressure side.

[0080] Variants with sterile filter with microbacterial action

[0081] The sterile filter 116 is designed to trap microbes, so that in addition to trapping particles, it can also trap bacteria or endotoxins.

[0082] All the mentioned variations, as long as they are not physically mutually exclusive or interdependent, can be combined in any way. In particular, all variations can be combined with... Figure 2 The basic version is combined.

[0083] List of reference numerals in the attached diagram:

[0084] 100 - process input water

[0085] 101 - solenoid valve

[0086] 102 - receiving reservoir

[0087] 103 - reverse osmosis pump

[0088] 104 - membrane

[0089] 105 - concentrate

[0090] 106 - solenoid valve

[0091] 107 - needle valve

[0092] 108 - permeate

[0093] 109 - junction

[0094] 110 - overflow valve

[0095] 111 - reverse osmosis device

[0096] 112 - permeate reservoir

[0097] 113 - pressure sensor

[0098] 114 - permeate pump

[0099] 115 - solenoid valve

[0100] 116 - sterile filter

[0101] 117 - volumetric flow sensor

[0102] 118 - pressure sensor

[0103] 119 - flow restrictor

[0104] 120 - pressure sensor

[0105] 121 - heater

[0106] 122 - temperature sensor

[0107] 123 - solenoid valve

[0108] 124 - temperature sensor

[0109] 125 - solenoid valve

[0110] 126 - pressure expansion vessel

[0111] 127 - check valve

[0112] 128 - check valve

[0113] 129 - venturi nozzle

[0114] 130 - reverse osmosis vessel

[0115] 131 - input line

[0116] 132 - connection line

[0117] 133 - annular line

[0118] 134 - access point

[0119] 135 - (concentrate) recirculation line

[0120] 136 - discharge

[0121] 137 - reverse osmosis stage

[0122] 138 - connection line

[0123] 138 - permeate stage

[0124] 140 - (permeate) circulation line

[0125] 141 - outlet line

[0126] 142 - return line

[0127] 143 - inlet

[0128] 144 - outlet

[0129] 150 - device control means

Claims

1. Water treatment apparatus for producing a permeate, in particular for a dialysis treatment, comprising: • a reverse osmosis stage (137) with a piping system comprising an input line (131) for process input water (100), a reverse osmosis pump (103) and a reverse osmosis vessel (130), wherein the reverse osmosis vessel (130) has an inlet (143) for process input water (100) from the reverse osmosis pump (103), a membrane (104) and an outlet (144) for permeate (108), • a permeate stage (139) with a piping system forming a circuit comprising a permeate tank (112), a permeate pump (114) and an access point (134) for connecting at least one consumer or access of permeate (108), wherein the reverse osmosis stage (137) and the permeate stage (139) are connected to each other by a connecting line (138) such that the reverse osmosis stage (137) supplies permeate (108) to the permeate stage (139), and wherein the circuit of the permeate stage (138) comprises a sterile filter (116).

2. Water treatment apparatus according to claim 1, wherein the sterile filter (116) is arranged downstream of the permeate pump (114) and upstream of the permeate tank (112).

3. Water treatment apparatus according to claim 2, wherein the access point (134) is arranged downstream of the sterile filter (116) and upstream of the permeate tank (112).

4. Water treatment apparatus according to any of the preceding claims, wherein between the access point (134) and the permeate tank (112) an overflow valve (110) or a flow restrictor (119) is arranged.

5. Water treatment apparatus according to any of the preceding claims, wherein there is an apparatus control device (150) which switches the reverse osmosis pump (103) on and off depending on the filling level in the permeate tank (112).

6. Water treatment apparatus according to any of the preceding claims, wherein there is a pressure-based filling level detection device for the permeate tank (112).

7. Water treatment apparatus according to any of the preceding claims, wherein the permeate pump (114) is pressure-regulated depending on the pressure in the circuit.

8. Water treatment apparatus according to claim 7, wherein a pressure sensor (118) for the regulation is arranged in the circuit between the access point (134) and a flow restrictor (119) which is arranged upstream of the permeate tank (112).

9. Water treatment apparatus according to any of the preceding claims, wherein the permeate pump (114) is volume flow-regulated depending on the throughput through the circuit.

10. Water treatment apparatus according to claim 9, wherein a volumetric flow sensor (117) for regulation is arranged in the circuit between a point of access (134) and an overflow valve (110), which is arranged upstream of a permeate tank (112).

11. Water treatment apparatus according to any of the preceding claims, wherein the permeate tank (112) is configured as a pressure expansion vessel (126).

12. Water treatment apparatus according to any of the preceding claims, wherein the connecting line (138) is designed in such a way that the entire permeate output of the reverse osmosis stage (137) is fed into the circuit of the permeate stage (139).

13. Water treatment apparatus according to any of the preceding claims, wherein the reverse osmosis stage (137) has a heater (121) for the process input water (100), which works according to the principle of a flow-through heater, the heater preferably being arranged between the reverse osmosis pump (103) and the reverse osmosis vessel (130).

14. Water treatment apparatus according to any of the preceding claims, wherein the reverse osmosis stage (137) has a recirculation line (135) for the concentrate (105) that is retained by the membrane (104).

15. Water treatment apparatus according to any of the preceding claims, wherein the reverse osmosis stage (137) has a receiving tank (102) for the intermediate storage of process input water (100).

16. Method for producing a permeate (108), in particular for a dialysis treatment, preferably with a water treatment apparatus according to any of the preceding claims, wherein the permeate (108) is produced according to the principle of reverse osmosis by means of a reverse osmosis pump (103) pressing the process input water (100) through a membrane (104), the permeate (108) produced being fed, preferably completely, into a permeate tank (112) and being circulated in a circuit connected to the permeate tank (112) by means of a permeate pump (114), wherein possible points of access or consumers of the permeate (102) can be connected to the circuit, and wherein the permeate (108) is guided through a sterile filter (116) in the circuit.

17. The method of claim 15, wherein, If the filling level of the permeate (108) in the permeate tank (112) exceeds a defined value, the reverse osmosis pump (103) is switched off.

18. Method according to any of claims 16 to 17, wherein the permeate pump (114) is regulated according to the pressure in the circuit.

19. Method according to claim 18, wherein the pressure is measured by means of a pressure sensor (118), which is arranged in the circuit between a point of access (134) for a point of access or consumer of the permeate (102) and a flow restrictor (119), which is arranged upstream of the permeate tank (112).

20. The method according to any one of claims 16 to 17, wherein the permeate pump (114) is adjusted as a function of the throughput through the circuit.

21. The method according to claim 18, wherein the throughput is measured by a volumetric flow sensor (117) arranged in the circuit between a take-off site (134) for the permeate (102) and an overflow valve (110) arranged upstream of a permeate storage tank (112).

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