Device for generating water for medical products

Abstract

A water generating device comprises a first system (300) and a second system (400) arranged sequentially along a main flow path (1). The first system is configured to treat influent water into treated water having reduced water hardness. The treated water is generated by a reverse osmosis (RO) unit (304) within the first system that receives influent water from a feed pump (302). The second system is configured to generate water for medical products from the treated water. A return flow path (8) is extended from a location between the first system and the second system to the feed side of the reverse osmosis (RO) unit. A starting procedure is performed by the water generating device by operating a valve device (314, 401) to close the main flow path between the first system and the second system and to open the return flow path, starting the feed pump and operating it for a specific time interval, and then operating the valve device to open the main flow path after the time interval.

Description

Technology Field

[0001] The present disclosure relates to a technique for generating medical product water. Background Technology

[0002] Many medical applications or uses require access to high-purity water. One such medical application is dialysis. The medical fluids used in dialysis include dialysis fluids and replacement fluids. Dialysis consumes large quantities of medical fluids. In some modalities of dialysis, pre-manufactured medical fluids are delivered to the point of care in pre-filled envelopes. For example, this is standard practice in extracorporeal blood therapy and peritoneal dialysis for patients with acute kidney injury (AKI). On the other hand, dialysis machines for, for example, hemodialysis, hemofiltration, and extracorporeal blood therapy for patients with chronic kidney disease (CKD) via hemodialysis filtration are typically configured to produce the required medical fluid by mixing one or more concentrates with water. In this context, water is typically produced primarily at dialysis clinics using expensive equipment for the production of high-purity water.

[0003] Transporting pre-manufactured medical fluids in pre-filled bags is undesirable from an environmental perspective. Pre-filled bags are also bulky and heavy to handle and require significant storage space. Therefore, in more aspects of dialysis treatment, it is preferable to use medical fluids produced on-demand at the site.

[0004] On-demand production of medical fluids for dialysis treatment requires access to water of adequate quality. The water used to produce medical fluids must meet strict requirements set by standards or guidelines. Water purity requirements for the production of medical fluids for dialysis are much stricter than those required for drinking, bathing, cooking, and other household uses. Equipment for purifying tap water must also be capable of treating various types and levels of impurities within the water. For example, urban tap water often contains residual disinfectant chemicals such as chlorine and chloramine. Furthermore, water hardness can vary significantly across different regions and water sources. Water distribution systems can also be a source of lead, copper, or zinc contamination due to pipe corrosion. Moreover, households using well water may have to deal with difficulties caused by varying amounts of nitrates, arsenic, and other organic compounds.

[0005] One technique commonly used for water purification is reverse osmosis (RO), in which RO membranes are used to separate ions, molecules, and particles from water. Additionally, ion exchangers (IEX) are commonly used for water purification purposes.

[0006] While equipment for producing high-purity water from tap water may be commercially available, existing equipment is expensive, bulky, and noisy; therefore, it is primarily useful in centralized facilities, such as those in hospitals or clinics, where the produced water can be generated in secluded areas and distributed to multiple dialysis machines. Where such centralized facilities are absent, for example, in a patient's home, or where centralized distribution of high-purity water is not feasible, water purification equipment suitable for use on a smaller scale is required to enable dialysis treatment. For example, small-scale water purification equipment can generate water for use by a single or a small number of dialysis machines. Ideally, such water purification equipment should have low structural complexity and be inexpensive in terms of both production and operating costs. Additionally, low noise levels during operation may be desirable. Such water purification equipment should preferably be compact and easy to maintain. It may be desirable to implement a water purification device as a portable, standalone device for versatile use. Furthermore, it is generally desirable to ensure that the water purification equipment is efficient not only in terms of water consumption but also in terms of power consumption.

[0007] The purpose is to overcome at least one or more limitations of the prior art, at least partially.

[0008] An additional objective is to provide a technique for generating medical product water in a robust and well-controlled manner.

[0009] Another objective is to provide the relevant technique that is efficient in terms of water consumption.

[0010] In addition to one or more of these purposes, additional purposes that may be presented from the description below are at least partially achieved by the apparatus for generating water for medical products according to the independent claim, the computer-implemented method, and the computer-readable medium, wherein the embodiments are defined by the independent claim.

[0011] A first aspect of the present disclosure is an apparatus for generating water for medical products. The apparatus comprises: a main flow path extending from a main water inlet to a main water outlet; a first system disposed in the main flow path and configured to treat influent water to reduce water hardness and consequently obtain treated water with reduced water hardness; and a second system disposed in the main flow path between the first system and the main water outlet, wherein the second system is configured to receive treated water from the first system and further treat the treated water for products. The first system comprises a reverse osmosis (RO) unit for use in treating influent water, and the main flow path comprises a feed line extending to a water inlet on the feed side of the reverse osmosis (RO) unit, and the first system comprises a feed pump disposed in the feed line to pressurize influent water at the water inlet of the reverse osmosis (RO) unit. The device further comprises: a return flow path arranged to fluidly connect a main flow path at a location between a first system and a second system to the feed side of a reverse osmosis (RO) unit; and a valve device operable to selectively guide treated water from the first system to the second system along the main flow path or to the feed side of the reverse osmosis (RO) unit along the return flow path. The device is configured to perform a start procedure, wherein, in the start procedure, the valve device is operated to close the main flow path and open the return flow path, the feed pump is started and operated for a specific time interval, and the valve device is operated to open the main flow path and selectively close the return flow path after the time interval.

[0012] A second aspect of the present disclosure is a computer-implemented method for operating an apparatus for generating water for medical products. The apparatus comprises: a main flow path extending from a main water inlet to a main water outlet; a first system disposed in the main flow path and configured to treat incoming water to reduce water hardness, thereby obtaining treated water with reduced hardness; and a second system disposed in the main flow path between the first system and the main water outlet, wherein the second system is configured to receive treated water from the first system and further treat said treated water for products. The first system comprises a first reverse osmosis (RO) unit for use in treating incoming water, and the apparatus comprises: a return flow path disposed to fluidly connect the main flow path at a location between the first system and the second system to the feed side of the reverse osmosis (RO) unit; and a valve device operable to selectively guide treated water from the first system to the second system or to the feed side of the reverse osmosis (RO) unit on the return flow path. The main flow path includes a feed line extending to a water inlet on the feed side of a reverse osmosis (RO) unit, and the first system includes a feed pump placed in the feed line to pressurize the influent water at the water inlet of the reverse osmosis (RO) unit. The method comprises the steps of: operating a valve device to close the main flow path and open the return flow path; starting the feed pump and operating the feed pump for a specific time interval; and operating the valve device to open the main flow path after the time interval.

[0013] A third aspect of the present disclosure is a computer-readable medium comprising program instructions that, when executed by a processor, cause the processor to perform a computer implementation method of the second aspect.

[0014] These embodiments provide a technique for starting a device for generating product water in a safe, robust, and well-controlled manner. The treated water generated by the first system is recirculated back to the reverse osmosis (RO) unit of the first system in the return flow path during startup. This recirculation allows the first system to be started independently of the second system while minimizing water waste. For example, a valve device may be selectively switched to guide the treated water from the first system to the second system when the reverse osmosis (RO) unit in the first system is known or considered to be producing treated water of appropriate quality. Sequential startup of the first and second systems, which are fluidly connected in series in the main flow path, may reduce the time required for the device to reach steady-state operation. Furthermore, the recirculation mitigates or eliminates the risk that the second system will receive treated water of inferior quality, for example, in terms of water hardness, during startup. This may extend the lifespan of the second system and / or reduce the need for maintenance of the second system.

[0015] Hereinafter, various embodiments of the first aspect are defined. These embodiments provide at least some of the aforementioned technical effects and benefits, as well as additional technical effects and benefits that are readily understood by those skilled in the art by considering, for example, the detailed description presented below.

[0016] In some embodiments, the return flow path extends to a location on the main flow path upstream of the feed pump.

[0017] In some embodiments, the device further comprises a sensor disposed between the first system and the valve device in the main flow path, the sensor being configured to generate a sensor signal indicating parameters related to the composition of the treated water, and the device being configured to determine the time interval based on the sensor signal.

[0018] In some embodiments, the composition-related parameter corresponds to electrical conductivity.

[0019] In some embodiments, the first system further comprises a drain line extending from a residual outlet on the feed side of a reverse osmosis (RO) unit, and a flow limiting device is disposed in the drain line to form a flow resistance at the residual outlet on the feed side of the reverse osmosis (RO) unit.

[0020] In some embodiments, the flow limiting device can be operated to change the flow resistance based on a control signal.

[0021] In some embodiments, the first system comprises a drain line and a feed line arranged in fluid communication to form a recirculation path from a residual outlet on the feed side of the reverse osmosis (RO) unit to a water inlet on the feed side of the reverse osmosis (RO) unit, and an auxiliary pump arranged in the recirculation path to provide additional flow along a second flow path.

[0022] In some embodiments, the auxiliary pump is placed in a connection line.

[0023] In some embodiments, the reverse osmosis (RO) unit forms a permeable side separated from the feed side by a semipermeable membrane, and the reverse osmosis (RO) unit includes a water inlet on the feed side and a permeable outlet on the permeable side, and the main flow path includes a first flow path from the water inlet to the permeable outlet through the semipermeable membrane, and the reverse osmosis (RO) unit further includes a residual outlet on the feed side to form a second flow path from the water inlet to the residual outlet along the semipermeable membrane on the feed side.

[0024] In some embodiments, the device further includes a storage tank positioned in the main flow path upstream of the first system and configured to maintain the inflow water for the first system at atmospheric pressure.

[0025] In some embodiments, the storage tank includes a water inlet port connected for fluid communication with a main water inlet, and the storage tank is configured to form an air gap above a predefined upper level of the inflow water inside the storage tank.

[0026] In some embodiments, the storage tank includes a level sensor for signaling at least one fluid level within the storage tank, and accordingly, a control device controls the inflow of water through a water inlet port to maintain an air gap within the storage tank.

[0027] In some embodiments, the device further includes a vent in the side wall of the storage tank, and the vent is configured to release both gas and water from the storage tank.

[0028] In some embodiments, the return flow path extends to a return port on the storage tank.

[0029] In some embodiments, the device further includes a recirculation path extending from a first location in a main flow path downstream of the second system to a second location in a main flow path upstream of the first system, and / or a third location in a main flow path between the first system and the second system, in order to recirculate product water generated by the second system.

[0030] In some embodiments, the first system includes a drain line for guiding reject water from a reverse osmosis (RO) unit to a drain, and the device further includes a heat transfer device configured to transfer heat between a first rocker in the drain line and a second rocker in a main flow path upstream of the reverse osmosis (RO) unit.

[0031] In some embodiments, the heat transfer device includes at least one of a heat exchanger and a heat pump.

[0032] In some embodiments, the device further includes a control device configured to operate a heat pump to achieve a target temperature of the influent water in a first reverse osmosis (RO) unit.

[0033] In some embodiments, the control device is configured to operate a heat pump to transfer heat from a first locus to a second locus.

[0034] In some embodiments, the control device is configured to selectively reverse the heat pump to transfer heat from the second rocker to the first rocker.

[0035] In some embodiments, the control device is configured to selectively reverse the heat pump based on a signal indicating the temperature and / or hardness of the inflow water into the first system.

[0036] In some embodiments, the heat pump is a thermoelectric heat pump.

[0037] In some embodiments, the second locus is upstream of a sensor configured to generate a sensor signal representing a composition-related parameter.

[0038] In some embodiments, the control device is configured to operate a heat pump to achieve a target temperature of the treated water from a sensor configured to generate a sensor signal indicating a composition-related parameter.

[0039] In some embodiments, the reverse osmosis (RO) unit is a sacrificial component that is detachably installed in the first system.

[0040] In some embodiments, the reverse osmosis (RO) unit has a target lifespan capable of producing 20,000 L to 100,000 L of the treated water, preferably 40,000 L to 70,000 L of the treated water.

[0041] In some embodiments, the target life is defined for influent water to a reverse osmosis (RO) unit having a hardness of 450 ppm and / or a conductivity of 2000 μS / cm, and for treated water produced at a flow rate of 1 L / min.

[0042] In some embodiments, the device is configured to generate product water at a point of care, and the device is configured to provide replacement of a first reverse osmosis (RO) unit by an untrained user at the point of care.

[0043] In some embodiments, the device further includes a monitoring device configured to evaluate a performance parameter to determine a flow resistance through a reverse osmosis (RO) unit based on an output signal of a sensor within the device and to detect the need for replacement of the reverse osmosis (RO) unit.

[0044] In some embodiments, the sensor comprises at least one of a pressure sensor in the main flow path upstream of the reverse osmosis (RO) unit, a flow meter in the main flow path downstream of the reverse osmosis (RO) unit, and a power sensor for measuring the power consumption of the feed pump.

[0045] In some embodiments, the second system includes a second reverse osmosis (RO) unit for use in treating treated water from the first system.

[0046] In some embodiments, the second reverse osmosis (RO) unit is permanently installed in the second system.

[0047] In some embodiments, the residual outlet of the second reverse osmosis (RO) unit is connected to fluidly communicate with the main flow path at an upstream location of the first system to recirculate residual water from the second reverse osmosis (RO) unit into the main flow path.

[0048] In some embodiments, the device further comprises a pretreatment system disposed in a main flow path and configured to receive raw water from a main water inlet and to provide pretreatment water by removing particles from at least the raw water, and the first system is fluidly connected to receive pretreatment water from the pretreatment system.

[0049] In some embodiments, the pretreatment system is also configured to remove chlorine from raw water.

[0050] In some embodiments, the device further comprises at least one radiation source positioned in the main flow path upstream of the reverse osmosis (RO) unit, and the radiation source is operable to emit UV radiation to remove chlorine in the influent water to the reverse osmosis (RO) unit.

[0051] Any embodiment of the first embodiment may be adapted as an embodiment of the second embodiment.

[0052] Other objects, modes, embodiments, features, and advantages may become apparent from the following detailed description, the appended claims, as well as the drawings. Brief explanation of the drawing

[0053] Figure 1 is a schematic diagram of an exemplary water purification device (WPA). FIGS. 2a to 2c are block diagrams of a system included in an exemplary water purification device (WPA), and FIG. 2d is a drawing of an exemplary reverse osmosis (RO) unit for use in a water purification device (WPA). FIGS. 3a to 3d are flowcharts of an exemplary method of operating a water purification device (WPA) in FIGS. 2a to 2c. FIG. 4a is a block diagram of an exemplary water purification device (WPA) configured according to the first concept, and FIG. 4b is a flowchart of an exemplary method of operating the water purification device (WPA) in FIG. 4a. FIG. 5 is a block diagram of an exemplary subassembly of a water purification device (WPA) configured according to the second concept. FIG. 6 is a block diagram of an exemplary water purification device (WPA) configured according to the third concept. FIG. 7 is a block diagram of an exemplary water purification device (WPA) configured according to the fourth concept. FIG. 8a is a block diagram of an exemplary water purification device (WPA) configured according to the fifth concept, and FIG. 8b is a flowchart of an exemplary method of operating the water purification device (WPA) in FIG. 8a. FIG. 9a is a block diagram of an exemplary water purification device (WPA) configured according to the sixth concept, and FIG. 9b is a flowchart of an exemplary method performed in relation to the water purification device (WPA) in FIG. 9a. FIG. 10a is a block diagram of an exemplary water purification device (WPA) configured according to the seventh concept, and FIG. 10b is a flowchart of an exemplary method of operating the water purification device (WPA) in FIG. 10a. FIG. 11 is a block diagram of an exemplary water purification device (WPA) according to a modified example. FIG. 12 is a block diagram of an exemplary water purification device (WPA) configured according to a variation of the first concept. FIG. 13a is a block diagram of an exemplary water purification device (WPA) having a heat transfer device, and FIG. 13b illustrates an exemplary heat transfer device. Specific details for implementing the invention

[0054] Now, embodiments will be described more faithfully below with reference to the accompanying drawings, which illustrate some embodiments, though not all. In fact, the subject matter of this disclosure may be embodied in a number of different forms and should not be interpreted as being limited to the embodiments described herein; rather, the embodiments described above are provided to enable this disclosure to satisfy applicable legal requirements. Similar reference numerals refer to similar elements throughout the detailed description.

[0055] Furthermore, it will be understood that, where possible, any of the advantages, features, functions, devices, and / or operable modes relating to any of the embodiments described herein and / or considered herein may be included in any of the other embodiments described herein and / or considered herein, and / or vice versa. Additionally, where possible, any term expressed in the singular form herein is intended to also include the plural form, and / or vice versa, unless otherwise explicitly stated. As used herein, "at least one" will mean "one or more," and these phrases are intended to be interchangeable. Accordingly, the terms "one" and / or "one thing" may mean "at least one" or "one or more," even if the phrases "one or more" or "at least one" are still used herein. As used herein, variations such as the words “include,” “include,” or “include” are used in an inclusive sense, except where otherwise required by contextual language or necessary connotations; that is, while specifying the presence of the mentioned features, they do not exclude the presence or addition of additional features in various embodiments.

[0056] Furthermore, it will be understood that while terms such as “first,” “second,” etc., may be used herein to describe various elements, these elements should not be limited by such terms. These terms are used solely to distinguish one element from another. For example, without departing from the scope of this disclosure, “first element” may also be referred to as “second element,” and likewise, “second element” may also be referred to as “first element.” As used herein, the terms “multiple,” “plural,” and “plural” are intended to mean that two or more elements are provided. The term “and / or” includes any combination of one or more of the associated and listed elements.

[0057] Well-known functions or structures may not be described in detail for the sake of brevity and / or clarity. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as universally understood by those skilled in the art to which this disclosure pertains.

[0058] The present disclosure relates to a technique for generating water for use in medical treatment of a human body or an animal body. As used herein, “medical treatment” refers to a remediation attempted for a health problem and includes any treatment involving contact between the body, including blood within the body, and water. The present disclosure may relate to current or future treatments in which water is mixed with one or more concentrates to form a medical fluid that is permitted to interact with a patient’s blood. Such treatments include dialysis, plasmapheresis, phlebolysis, extracorporeal membrane oxygenation, assisted blood circulation, extracorporeal liver support / dialysis, etc. Such “on-demand generation” of medical fluid is expected to become increasingly common in the future. Such on-demand generation allows medical fluid to be generated in the required amount and also allows the composition of the medical fluid to be controlled. The present disclosure may relate, in particular, to generating small amounts of medical fluid on demand for use in a single dialysis machine or a small number of dialysis machines. Accordingly, the technique described herein can be used in a patient's home or clinic to enable the generation of medical fluids when needed.

[0059] As mentioned, water purification techniques are applicable to dialysis treatment. As used herein, "dialysis treatment" refers to any treatment that replaces or supplements a patient's renal function through the use of dialysis fluid. Dialysis treatment includes, but is not intended to be limited to, extracorporeal (EC) blood treatment and peritoneal dialysis (PD) treatment. Examples of extracorporeal blood treatment include hemodialysis (HD), hemofiltration (HF), and hemodiafiltration (HDF).

[0060] FIG. 1 corresponds to a schematic overview of a water purification device (WPA) according to some embodiments. The water purification device includes a water inlet (1') for inputting raw water (SWA) from a water source (10) and a water outlet (1") for outputting purified water (PWA). The raw water may be of any quality. In some embodiments, the raw water is tap water (drinking water) or some form of pretreated tap water. The water inlet (1') may include a connector for engaging with a corresponding connector associated with the raw water (10). Likewise, the water outlet (1") may include a connector for engaging with a corresponding connector associated with a receiving device (not shown). The receiving device may be any device configured to produce a medical fluid by mixing the purified water with one or more concentrates. In some embodiments, the receiving device is a dialysis machine or a standalone device for producing a medical fluid for use in a dialysis treatment. In some embodiments, the water purification device (WPA) is integrated with the receiving device. For example, the water purification device (WPA) and the receiving device may be included in the same flow path.

[0061] A water purification device (WPA) is operable to treat raw water (SWA) into product water (PWA), said product water having a quality sufficient for use in intended medical treatment, at least in terms of impurities. Accordingly, the water purification device (WPA) is configured to perform purification treatment of raw water (SWA) to produce product water (PWA). As used herein, "purification" refers to the removal of impurities such as undesirable chemicals, biological contaminants, suspended solids, and gases. This is not intended to imply that the purified water is sterile or substantially free of microbial activity, although such cases may apply. In non-limiting examples applicable to so-called “dialysis water” or “dialysis water,” the product water (PWA) meets, at a minimum, the following maximum acceptable levels of toxic chemicals known to be toxic in dialysis facilities: aluminum 0.01 ppm, copper 0.1 ppm, fluoride 0.2 ppm, lead 0.005 ppm, nitrate (as N) 2 ppm, sulfate 100 ppm, zinc 0.1 ppm, and total chlorine 0.1 ppm. In some embodiments, the product water (PWA) (or medical fluid produced from the product water (PWA)) undergoes additional treatment for the removal of microorganisms, endotoxins, etc. Such additional treatment may involve any conventional technique for sterilization, including filtration by one or more ultrafilters. However, in some embodiments, the product water (PWA) is generated by a water purification device (WPA) to meet all requirements of "dialysis water" or "dialysis water" according to, for example, ANSI / AAMI / ISO 23500-3:2019.

[0062] A water purification device (WPA) includes a main flow path (1) ("main path") extending from a water inlet (1') to a water outlet (1"). In the example of FIG. 1, a pretreatment system (100) is placed in the main flow path (1) to receive and treat raw water (SWA). An optional pretreatment system (100) may be configured to treat the raw water (SWA) for the removal of at least particles. In some embodiments, the pretreatment system (100) is configured to remove particles having a nominal size of 1 μm or more, i.e., to allow particles having a nominal size of less than 1 μm to pass through. In some embodiments, the pretreatment system (100) is additionally configured to reduce one or more contaminants, such as volatile organic compounds (VOCs) and trihalomethanes (THMs), that may be present in the raw water (SWA). In some embodiments, the pretreatment system (100) is also configured to remove chlorine from the raw water (SWA). It is configured to effectively remove. As used herein, "effectively removed" means that the total amount of chlorine in the dechlorinated water is 0.1 mg / L (0.1 ppm) or less. The water produced by the pretreatment system (100) is referred to herein as "pretreated water." In some embodiments, the pretreated water may be referred to as "dechlorinated water." Chlorine may exist in the water in a free form and / or a combined form. The free form may include dissolved hypochlorite ions, hypochlorous acid, and chlorine gas. The combined form may include chloramines that kill bacteria and oxidize organic matter. Examples of such chloramines include monochloramine, dichloramine, and trichloramine. The total amount of chlorine is given by the sum of the chlorine in the free form and the chlorine in the combined form.

[0063] As further exemplified below, dechlorination can be performed, alternatively or additionally, by irradiating the water in a water purification device (WPA) with UV light.

[0064] In the example of FIG. 1, a storage tank or tank (200) is placed downstream of the pretreatment system (100) to collect pretreatment water.

[0065] A first purification system (300) ("first system" or "first main system", PS1) is positioned downstream of the tank (200) to receive and treat the influent water. The first system (300) is configured to reduce the water hardness of at least the influent water. This process is generally referred to as "water softening" and involves the removal of at least calcium and magnesium. The water produced by the first system (300) is referred herein as "treated water" or "softened water." Water hardness is the amount of polyvalent cations and generally corresponds to the sum of dissolved calcium and magnesium in the water. Water hardness may be classified as carbonate hardness or non-carbonate hardness depending on the presence of counter-anions in the water. This hardness classification may be given as an equivalence unit of mgCaCO3 / L. The first system (300) may also be configured to reduce minerals and / or TDS (total dissolved solids) in the influent water.

[0066] One function of the first system (300) is to reduce water hardness to alleviate or even prevent scaling of downstream components within a water purification device (WPA), such as the second purification system (400) (see reference below). In some embodiments, the first system (300) is configured to produce treated water having a water hardness of less than 60 ppm (mgCaCO3 / L), preferably less than 30 ppm (mgCaCO3 / L), 20 ppm (mgCaCO3 / L), or 10 ppm (mgCaCO3 / L). In some embodiments, the first system (300) is configured to reduce the water hardness of the influent water by at least 90%, preferably at least 95%, in terms of equivalent units of mgCaCO3 / L.

[0067] In some embodiments, the first system (300) is configured to treat the influent water by reverse osmosis (RO) to reduce water hardness. This means that the first system (300) includes at least one reverse osmosis (RO) unit for use in treating raw water (SWA). The reverse osmosis (RO) unit includes a reverse osmosis (RO) filter arranged to separate ions, molecules, and particles from the influent water. Specifically, the reverse osmosis (RO) unit is configured to perform cross-flow filtration (also known as tangential flow filtration) in which most of the influent water ("fed water") does not travel through the reverse osmosis (RO) filter but travels tangentially across the surface of the reverse osmosis (RO) filter. The filtered water that passes through the reverse osmosis (RO) filter is referred to as "permeate" or "permeate water," and the unfiltered water is referred to as "residue" or "reject water." An example of a reverse osmosis (RO) unit will be described below with reference to FIG. 2d. Those skilled in the art will understand that reverse osmosis (RO) is a non-selective technique and that treatment by reverse osmosis (RO) will not only reduce water hardness but also remove impurities unrelated to water hardness. These impurities may include various inorganic and organic compounds.

[0068] A second purification system (400) ("second system" or "second main system", PS2) is positioned downstream of the first system (300) and is configured to perform final treatment of the treated water to produce purified water (PWA). Accordingly, the second system (400) may be configured to remove remaining impurities not removed by the first system (300) so that the purified water (PWA) has the required purity. Alternatively, or additionally, the second system (400) may be configured to reduce the microbial load of the treated water from the first system (300).

[0069] The second system (400) may implement any suitable purification technique, such as membrane filtration, ion exchange, electrode ionization (EDI), or any combination thereof. Membrane filtration may involve reverse osmosis (RO). Accordingly, in some embodiments, the second system (400) includes at least one reverse osmosis (RO) unit for use in treating influent water. In some embodiments, the second system (400) includes at least one ion exchanger (IEX) instead of or in addition to the reverse osmosis (RO) unit. As is known in the art, the ion exchanger can be operated to remove ionic impurities from water by replacing the corresponding ionic impurities with another ionic substance. Specifically, the anion is OH - It is replaced by, and the cation is H + It is replaced by, at this time, OH - and H + They combine to form water molecules. Typical ion exchangers are ion exchange resins (functionalized porous polymers or gel polymers), zeolites, montmorillonite, clay, or soil humus.

[0070] The operation of the water purification device (WPA) is controlled by a control signal generated and output by a control device (500). The control signal is collectively represented as [CS] in FIG. 1 and may be provided to components (not shown) operable in pumps, valves, heaters, flow restrictors, etc. The control device (500) is configured to generate a control signal based on a measurement signal collectively represented as [MS]. The measurement signal represents the current values ​​of various state parameters of the water purification device (WPA), such as pressure, temperature, flow rate, chemical composition, conductivity, etc. At least some of the measurement signals may be provided by sensors (not shown) within the water purification device (WPA). The control device (500) includes a combination of a processing circuit (501) and a memory (502). The memory (502) may store program instructions executed by the processing circuit (501) to implement the operation of the control device (500). Program instructions may be provided to a control device (500) on a computer-readable medium, which may be a tangible (non-transient) product (e.g., magnetic medium, optical disc, read-only memory, flash memory, etc.) or to a radio signal. The processing circuit (501) may include a general-purpose processor, e.g., a microprocessor, a microcontroller, a CPU, a DSP (digital signal processor), a GPU (graphics processing unit), etc., or a specialized processor, e.g., an ASIC (application specific integrated circuit) or a FPGA (field programmable gate array), or any combination thereof. The memory (502) may include volatile memory and / or non-volatile memory, such as ROM (read-only memory), RAM (random access memory), or flash memory.

[0071] As illustrated, the control device (500) may be connected to a human-machine interface (HMI) device (503). The term “HMI device” is intended to include any device capable of performing guided human-machine interaction, including displaying information or commands and receiving input data. For example, the HMI device (503) may include a combination of a display device and data input hardware. The data input hardware may include one or more of a keyboard, a keypad, a computer mouse, control buttons, a touch panel, a microphone and voice control unit, a camera and gesture control unit, etc. In one embodiment, the HMI device (503) is a touch-sensitive display also known as a touch screen or includes such a touch-sensitive display. Alternatively or additionally, the HMI device (503) may include a speaker or projector for providing information or commands to a user.

[0072] Providing a pretreatment system (100) to a water purification unit (WPA) can extend the effective lifespan of the systems (300, 400) and / or reduce the need for maintenance by reducing the amount of particles / solids and contaminants in the water to be treated by these systems. Furthermore, as previously mentioned, the pretreatment system (100) may be configured to generate dechlorinated water. Chlorine is strongly oxidized, and high levels of chlorine in the influent water to the reverse osmosis (RO) unit are known to cause irreversible damage to the corresponding reverse osmosis (RO) filter. Therefore, it may be desirable to ensure that the feedwater to the reverse osmosis (RO) unit in the first system (300) is sufficiently dechlorinated by applying UV radiation to the water by the pretreatment system (100) and / or elsewhere in the water purification unit (WPA). Additionally, it may be noted that the ion exchanger is also likely to be irreversibly damaged by chlorine.

[0073] The provision of the tank (200) serves to decouple the operation of the system (300, 400) from the supply of raw water (SWA) and (if present) the operation of the pretreatment system (100). This can facilitate the design and / or operation of the system (300, 400). Additional technical advantages of the tank (200) are discussed below with reference to FIG. 2a.

[0074] In some embodiments, depending on the required performance of the water purification device (WPA) and the quality of the raw water, the pretreatment system (100) and / or tank (200) may be omitted.

[0075] In some embodiments, the second system (400) primarily provides the function of reducing the microbial load of the treated water from the first system (300). Thus, in some embodiments, while the main portion of the chemical substances ("impurities") present in the raw water (SWA) is removed by the first system (300), the second system (400) has the primary function of reducing the microbial load of the treated water from the first system (300) so that the purified water (PWA) output by the water purification device (WPA) meets applicable requirements. As noted above, when the first system (300) involves a non-selective purification technique such as reverse osmosis (RO), most chemical compounds will be affected by purification as well as water hardness. This functional separation of the first system (300) and the second system (400) is advantageous in that it enables the individual optimization of the respective systems (300, 400).

[0076] By connecting the systems (300, 400) in series, the first system (300) is exposed to more impurities than the second system (400). This will extend the operating life of the second system (400) and, if desired, allow the second system (400) to include more advanced / sensitive purification equipment. On the other hand, the first system (300) may require additional consideration to ensure proper operation of the water purification device (WPA) over time. As previously mentioned, the first system (300) may include one or more reverse osmosis (RO) units. In some embodiments, the first system (300) may be configured to perform automated cleaning, disinfection, or sterilization of the reverse osmosis (RO) filter in the corresponding reverse osmosis (RO) unit included in the first system. The above cleaning may involve, for example, flushing the reverse osmosis (RO) filter with water, wherein the water may, for example, be heated to a maximum of 45°C or may not be heated. In some embodiments described in more detail below with reference to FIG. 4a, at least one reverse osmosis (RO) unit in the first system (300) is configured as a sacrificial or disposable component that is detachably installed in the first system (300). By doing so, the reverse osmosis (RO) unit may be replaced as needed, for example, as a result of scaling and / or when the reverse osmosis (RO) filter is deemed clogged with impurities at regular service intervals. The use of a disposable reverse osmosis (RO) unit may appear to increase the operating cost of the water purification unit (WPA). However, using a disposable reverse osmosis (RO) unit as proposed herein eliminates the need for a conventional water softener in the water purification unit (WPA). Many conventional water softeners are bulky, expensive, and may require supervision and periodic maintenance. Therefore, in practice, the proposed technique using disposable reverse osmosis (RO) units leads to cost reduction.Furthermore, by providing the second system (400), the reverse osmosis (RO) unit in the first system (300) does not need to be a high-end product, that is, a highly qualified product with high purification performance. Instead, a relatively simple and inexpensive low-end reverse osmosis (RO) unit, for example, a commercially available under-the-sink reverse osmosis (RO) unit, may be used. Currently, the cost ratio between high-end and low-end reverse osmosis (RO) units in the market is at least 5 to 10 times. Therefore, replacing the reverse osmosis (RO) unit will have only a negligible impact on the operating costs of the water purification device (WPA). Furthermore, the replacement of the reverse osmosis (RO) unit(s) in the first system (300) may lower the requirements for the purification performance of the second system (400), thereby enabling a reduction in the production costs of the water purification device (WPA).

[0077] FIGS. 2a through 2c illustrate a water purification device (WPA) according to a detailed embodiment. The water purification device (WPA) is divided into subsets in FIGS. 2a through 2c, wherein fluid connections between different subsets are represented by encircled letters A through G. A method of operating the water purification device (WPA) will be described with reference to FIGS. 3a through 3d. This method may be performed by the control device (500) in FIG. 1. The water purification device (WPA) described with reference to FIGS. 2 and 3 embodies various inventive concepts that provide distinct technical advantages. Some of these concepts, in addition to those briefly presented in relation to FIGS. 2 and 3, will be presented and discussed in more detail below with reference to FIGS. 4 through 10.

[0078] FIG. 2a is a block diagram of an upstream portion of a water purification device (WPA) comprising a pretreatment system (100) and a tank (200). Raw water (SWA) is received at A, and a main flow path (1) extends from A to C. It is assumed that the raw water (SWA) is sufficiently pressurized to flow into the tank (200) through the pretreatment system (100) along the main flow path (1). In the flow direction along the main flow path (1), the pretreatment system (100) includes a one-way valve (101), an inlet valve (102), a filtration device (103), a flow limiter (104), a temperature sensor (105), and a composition sensor (106). The filtration device (103) is configured to perform both particle removal and dechlorination. In one embodiment, the filtration device includes activated carbon (AC) filters (103A, 103B) connected in series. Each activated carbon (AC) filter (103A, 103B) is formed by a container holding activated carbon, also known as activated charcoal. The activated carbon is treated (activated) to have small, low-volume pores that increase the surface area available for adsorption and / or chemical reactions. The activated carbon forms a bed inside the container. The bed of activated carbon is positioned to remove chlorine from the influent and to absorb toxic substances and pesticides. In an exemplary embodiment, the bed of activated carbon is positioned to remove free-form chlorine and combined-form chlorine. In a further exemplary embodiment, the bed of activated carbon is also positioned to reduce organic compounds (TOC, Total Organic Carbon), including pesticides, in the influent. The bed of activated carbon also essentially filters particles from the influent.

[0079] A flow limiter (104) is included to generate backing pressure in the main flow path (1) to limit the flow of water through the filtration device (103). An inlet valve (102) ("main inlet valve") may be operable via a control signal (VC1) to selectively open and close the main flow path (1) to control the acceptance of raw water (SWA) into the water purification device (WPA). Alternatively, the inlet valve (102) may be a flow control valve operable to accept raw water (SWA) into the main flow path (1) at a variable flow rate.

[0080] A one-way valve (101) is included to prevent flow reversal in the main flow path (1) and consequent backflow through the filtration device (103). A temperature sensor (105) is configured to provide a measurement signal (T1) indicating the temperature of the raw water (SWA). A composition sensor (106) is configured to provide a signal (C1). When used herein, the composition sensor is configured to provide a measurement signal indicating the amount of at least one substance in the water. For example, the composition sensor may be a conductivity sensor (or equivalently a resistivity sensor), or a concentration sensor, for example, an ion-selective sensor. The signals (T1, C1) may be used by a control device (500) to control the operation of the water purification device (WPA).

[0081] A tank (200) is positioned to receive and collect pretreatment water from a pretreatment system (100). The tank (200) includes a level sensor (201) configured to indicate at least one fluid level in the tank (200) via a measurement signal (L1). Thus, the level sensor (201) may signal when water reaches one or more discrete levels, or may indicate the fluid level along a continuous scale. The measurement signal (L1) enables a control device (500) to control the level of water in the tank (200). The tank (200) includes a plurality of ports (202 to 206). A first inlet port (202) for pretreatment water is formed in the upper part of the tank (200). Thus, the first inlet port (202) is connected to the main flow path (1). An outlet port (203) is formed in the lower part of the tank (200) and connected to the main flow path (1). Thus, the tank (200) is fluidly connected to the first system (300) through the outlet port (203). A second inlet port (204) is formed in the upper part and connected to the first return line (8), the first return line (8) is fluidly connected to receive treated water processed by the first system (300) and the second system (400), respectively (see FIG. 2b and FIG. 2c). A third inlet port (205) is formed in the upper part of the tank (200) and connected to the second return line (2B), the second return line (2B) is fluidly connected to receive residue ("wastewater") from the second treatment system (400). In some embodiments, at least one of the inlet ports (202, 204, 205) is connected to a spray nozzle (not shown) inside the tank (200) for dispersing the inflow water. The inlet ports (204, 205) may be merged into a common port. A gas outlet or vent (206) is formed on the side of the tank (200). The vent (206) allows gas to escape from the tank (200), as indicated by the dashed arrow.Therefore, the water is maintained at atmospheric pressure in the tank (200).

[0082] In some embodiments, the amount of water in the tank (200) is controlled to form an air gap (207) at the top of the tank (200) by ensuring that the fluid level in the tank (200) does not rise above a predefined maximum level in the tank (200). The control device (500) may be configured to control the fluid level in the tank by controlling the inlet valve (102). Depending on the type of level sensor (201), the fluid level in the tank (200) may be allowed to change during the operation of the water purification device (WPA) or may not be allowed to change during the operation of the water purification device (WPA). If the first inlet port (202) is positioned above a predefined maximum level, the risk of water flowing back from the tank (200) toward the pretreatment system (100) is minimized, as such backflow can interfere with the operation of the filtration device (103). Likewise, the air gap (207) prevents backflow into the inlet ports (204, 205) if the inlet ports (204, 205) are installed above a predefined maximum level. The air gap (207) also acts as a barrier against microorganisms in relation to the inlet ports (204, 205). A layer of activated carbon is known to act as a nutrient-rich environment for microorganisms, and thus, the pretreatment system (100) can be a key point for the inflow of microorganisms into the water purification device (WPA). The air gap (207) will mitigate microbial contamination of the return line (8, 2B). Another technical advantage of the tank (200) is the ability of the tank to be used as a flow monitor via the signal (L1). According to an embodiment, the control device (500) may be configured to detect whether the fluid level cannot be maintained at a predefined maximum level in the tank (200), whether the fluid level cannot reach a predefined operating level in the tank, or whether the fluid level reaches a predefined lower level in the tank (200).This may indicate a malfunction of the pretreatment system (100) or the water source (10), or cause the control device (500) to stop the operation of the water purification device (WPA). Another technical advantage of the tank (200) is the ability to enable thermal expansion of the water in the water purification device (WPA). This may be particularly relevant when the water purification device (WPA) is configured to be intermittently cleaned (sterilized) by thermal disinfection. The provision of a vent (206) and the resulting atmospheric pressure within the tank (200) are advantageous for various reasons. This will enable the removal of air and other gases that may be released from the water within the tank (200). Furthermore, since water is recirculated from the first system (300) and the second system (400) back to the tank (200), this enables the continuous removal of gas from the entire hydraulic circuit of the water purification device (WPA), including the reverse osmosis (RO) unit in the systems (300, 400) (see below). Furthermore, during the startup of the water purification device (WPA), gas may be present in the hydraulic circuit, and such gas needs to be vented. Furthermore, the removal of gas from the hydraulic circuit becomes significant whenever the hydraulic circuit is opened during service and maintenance, for example, when the reverse osmosis (RO) unit is replaced with a new reverse osmosis (RO) unit. Another advantage of having the tank (200) exhibit atmospheric pressure is that it facilitates the recirculation of water from the first system (300) and the second system (400) through the return line (8, 2B).

[0083] In the example presented in FIG. 2a, the vent (206) is positioned at a location spaced apart from the top of the tank (200) on the side wall of the tank (200) to define an overflow or spillway for water. Thus, the vent (206) is configured to allow not only gas but also water to escape from the tank (200). By this, the vent (206) is positioned to define the highest fluid level achievable in the tank (200), thereby ensuring an air gap at the top of the tank (200). If water level control in the tank (200) fails for any reason, excess water will flow through the vent (206), and the air gap (207) will be maintained.

[0084] FIG. 2b is a block diagram of a first system (300) in a water purification device (WPA) according to one example. In FIG. 2b, the main flow path (1) extends from C to E. In the flow direction along the main flow path (1), the first system (300) includes a UV irradiation device (301), a feed pump (302), a pressure sensor (303), a reverse osmosis (RO) unit (304), a temperature sensor (310), a composition sensor (311), a flow switch (312), and a heater (313). It will be understood that each of these components provides a specific function in the context of the presented example, but not all components need to be included as shown. For example, any of the components (301 to 303, 310 to 313) may be omitted or placed elsewhere in other examples of the first system (300).

[0085] The pressure sensor (303) is configured to provide a measurement signal (P1) indicating hydraulic pressure (water pressure). The sensors (310, 311) each provide corresponding measurement signals (T2, C2) indicating water temperature and moisture composition. The signals (P1, T2, C2) can be used by a control device (500) to control the operation of the water purification device (WPA).

[0086] The heater (313) can be operated to heat water. In some embodiments, the heater (313) is a flow-through heater. In some embodiments, the control device (500) operates the heater (313) by feedforward control based on signals (T1) and / or signals (T2) to achieve a target temperature of water entering the second system (400). In other embodiments, the control device (500) operates the heater (313) by feedback control based on a measurement signal (T3) from a temperature sensor (411) (see below) in the second system (400).

[0087] A flow switch (312) is included as a safety measure to prevent the heater (313) from being activated when the flow rate of water passing through the heater (313) is too low, because if the heater (313) is activated when the flow rate of water passing through the heater (313) is too low, it may cause irreversible damage to the heater (313). Accordingly, the flow switch (312) is configured to autonomously disable the heater (313) when the flow rate of water through the flow switch (312) is below a preset threshold value.

[0088] A UV irradiation device (301) is included to reduce microbial activity in the water passing through. By installing the UV irradiation device (301) upstream of the reverse osmosis (RO) unit (304), the microbial load entering the reverse osmosis (RO) unit (304) and other downstream components will be reduced. This will extend the lifespan of the first system (300). The UV irradiation device (301) may include a treatment chamber for receiving influent water and at least one UV source within the treatment chamber. The UV source is operable to generate UV radiation to irradiate at least a portion of the treatment chamber. By doing so, the UV radiation interacts with the fluid within the treatment chamber. The flow of water through the treatment chamber may be intermittent or continuous. In some embodiments, the UV irradiation device (301) is configured to additionally remove chlorine from the water passing through. This can be achieved by increasing the irradiation power of the UV source and / or by limiting the emitted UV radiation to wavelengths that are highly absorbed by chlorine in water, such as dichloramine and monochloramine. Thus, the UV irradiation device (301) may be installed to complement the pretreatment system (100) or even to replace the dechlorination function of the pretreatment system (100). Generally, the UV irradiation device (301) configured to perform dechlorination may be installed at any location in the main flow path (1) upstream of the first reverse osmosis (RO) unit (304).

[0089] The reverse osmosis (RO) unit (304) is constructed of a conventional structure and includes a semipermeable filter or a semipermeable membrane (304'). The reverse osmosis (RO) membrane (304') is generally composed of a thin-film cross-linked composite polymer and can withstand relatively high hydraulic pressure. For example, the reverse osmosis (RO) membrane (304') may be a spirally wound membrane or a flat sheet membrane. An enlarged view of the reverse osmosis (RO) unit (304) is shown in FIG. 2d. The reverse osmosis (RO) membrane (304') separates the main body of the reverse osmosis (RO) unit (304) into a feed side or feed chamber (304") and a permeation side or permeation chamber (304'). The reverse osmosis (RO) unit (304) comprises one or more inlet ports (304A') (one inlet port is illustrated) and one or more outlet ports (304C') (one outlet port is illustrated) on the feed side (304"), and one or more outlet ports (304B') on the permeation side (304'"). It will be understood that the specific arrangement of the reverse osmosis (RO) membrane (304') and ports (304A', 304B', 304C') in FIG. 2d is presented merely as a non-limiting example. As noted above, the reverse osmosis (RO) unit (304) operates by cross-flow filtration. This filtration is achieved by allowing water to flow along the reverse osmosis (RO) membrane (304'). In FIG. 2d, this is achieved by the appropriate positioning of the inlet port (304A') and the outlet port (304C') on the feed side (304"). Permeate passes through the reverse osmosis (RO) membrane (304'), while wastewater exits the reverse osmosis (RO) unit (304) through the outlet port (304C'). The fluid pressure on the feed side (304") needs to be sufficient to overcome the osmotic pressure generated by the solute dissolved in the water.Accordingly, the filtered water is forced across a reverse osmosis (RO) membrane (304') to form a permeate stream through the outlet (304B'), while dissolved solutes are excluded and discharged as wastewater at a higher concentration. The feed-side fluid pressure may be in the range of 5 bar to 50 bar, typically 5 bar to 15 bar. At a general level, as indicated by the dashed arrow in FIG. 2d, the reverse osmosis (RO) unit (304) can be seen as forming a first flow path (FP1) extending from the inlet port (304A') through the reverse osmosis (RO) membrane (304') to the outlet port (304B'), and a second flow path (FP2) extending along the reverse osmosis (RO) membrane (304') from the inlet port (304A') on the feed side (304") to the outlet port (304C'). It will be recognized that the first flow path (FP1) is part of the main flow path (1) through the water purification device (WPA).

[0090] Referring to FIG. 2b, the fluid pressure on the feed side of the reverse osmosis (RO) unit (304) is formed by a feed pump (302) (also known as a booster pump). The pumping rate or pumping speed of the feed pump (302) is set by a control signal (PC1). The fluid pressure on the feed side can be monitored through a measurement signal (P1) of a pressure sensor (303) placed between the feed pump (302) and the reverse osmosis (RO) unit (304). A drain line (2A) is connected to receive wastewater from the reverse osmosis (RO) unit (304). The drain line (2A) extends from an outlet port on the feed side of the reverse osmosis (RO) unit (304) to a drain (309) or a receptacle for wastewater. A flow limiting device ("flow limiter") (306) is placed on the drain line (2A) to maintain a desired fluid pressure on the feed side of the reverse osmosis (RO) unit (304). The flow limiter (306) may be fixed or adjustable. For example, the flow limiter (306) may include a small orifice, a needle valve, or other variable orifice valve. In the example presented, a bypass line (4A) is connected to extend between locations on the drain line (2A) upstream and downstream of the flow limiter (306). The bypass line (4A) includes a drain valve (307) operable to selectively close and open the bypass line (4A) under the influence of a control signal (VC2). Downstream of the flow limiter (306) and the bypass line (4), an additional drain valve (308) is placed on the drain line (2A). An additional drain valve (308) can be operated to selectively close and open the drain line (2A) under the influence of a control signal (VC3). By opening the drain valves (307, 308), the entire volume of wastewater is allowed to flow into the drain line (2A) and out of the water purification device (WPA) to the drain (309).This bypass state may be advantageous for purging wastewater during the initial use of the reverse osmosis (RO) unit (304), for example, when the reverse osmosis (RO) unit (304) is replaced with a new reverse osmosis (RO) unit. Additionally, the bypass state may facilitate drain operation in which most or all of the water in the water purification device (WPA) is discharged from the water purification device (WPA) to the drain (309). In some embodiments, the flow restrictor (306) is motorized and can adjust the flow resistance of the flow restrictor in response to a control signal (e.g., FC1 in FIG. 5). When such a motorized flow restrictor (306) is provided, the valves (307, 308) and the bypass line (4A) may be omitted.

[0091] In the example of FIG. 2b, the connection line (3A) is arranged to fluidly connect the drain line (2A) at a location upstream of the flow restrictor (306) to the main flow path (1) at a location between the feed pump (302) and the reverse osmosis (RO) unit (304). By doing so, a water recirculation path or water recirculation loop is formed between the outlet port and the inlet port on the feed side of the reverse osmosis (RO) unit (304). The water recirculation path can be used to maintain a high-velocity water flow on the feed side of the reverse osmosis (RO) unit (304), thereby reducing the amount of water that would otherwise have been discarded into the drain. An auxiliary pump ("recirculation pump") (305) is placed within the recirculation path to increase the fluid velocity or fluid flow rate along the reverse osmosis (RO) membrane (304') sufficiently to suppress local concentration increase near the membrane surface. These locally increased concentrations may cause contamination of the reverse osmosis (RO) membrane (304') depending on the hardness of the inflow water into the reverse osmosis (RO) unit (304). The term “contamination” includes the build-up of any kind of layer on the surface of the reverse osmosis (RO) membrane (304'), including biofouling and scaling. The pumping rate or pumping speed of the recirculation pump (305) is set by a control signal (PC2).

[0092] In a modified example, the recirculation pump (305) and the connection line (3A) are omitted. In another modified example, the recirculation pump (305) is omitted, and the connection line (3A) is positioned to fluidly connect the drain line (2A) to the main flow path (1) at a location upstream of the feed pump (302) to form a recirculation path. Thereby, the suction generated by operating the feed pump (302) will cause the recirculation of water through the connection line (3A). A flow restrictor may be placed in the connection line (3A) to control the recirculating flow.

[0093] Although it is possible to omit the recirculation pump (305) and the connection line (3A), the combination of the feed pump (302) and the recirculation pump (305) is expected to lead to improved performance, reduced noise, and reduced power consumption. If only the feed pump (302) exists in the reverse osmosis (RO) unit (304), this feed pump needs to have a larger capacity to generate both the desired pressure and the recirculated flow. If the feed pump (302) is supplemented by the recirculation pump (305), both pumps can have lower capacities, and since two lower-capacity pumps are cheaper than one higher-capacity pump, this results in less noise and lower costs. Additionally, it should be noted that the two pumps (302, 305) perform different purposes, which are difficult to accommodate by a single pump; in other words, the two pumps perform the role of boosting pressure on one hand and boosting the flow rate on the other. In the example presented, the recirculation pump (305) is located in the connection line (3A), which is considered advantageous compared to having the recirculation pump (305) in the main flow path (1). The pressure sensor (303) may be located outside the recirculation path or inside the recirculation path, as illustrated.

[0094] In the example presented, the reverse osmosis (RO) unit (304) is detachably installed in the water purification device (WPA). To this end, terminal connectors (304A, 304B) for detachable attachment to the inlet port (304A') and outlet port (304B') of the reverse osmosis (RO) unit (304) are provided in the main flow path (1), and terminal connector (304C) for detachable attachment to the outlet port (304C') of the reverse osmosis (RO) unit (304) is provided in the drain line (2A).

[0095] The return line (8) is fluidly connected to the main flow path (1) downstream of the heater (313). As indicated by B, the return line (8) extends to the inlet port (204) on the tank (200) and thus serves to recirculate the treated water to the tank (200). A control valve (314) ("return path valve") is placed in the return line (8). The control valve (314) can be operated to selectively close and open the return line (8) under the influence of a control signal (VC4). Even if the fluid pressure is significantly lower on the permeate side compared to the feed side, the water exiting the first system (300) may be pressurized higher than atmospheric pressure. Therefore, as illustrated, a flow restrictor (315) may be placed in the return line (8) to cause a pressure drop in the return line (8) and to enable controlled flow of water from the first system (300) into the tank (200). As shown in FIG. 2b, an additional return line (5) from the second system (400) is fluidly connected to or merged with the return line (8). Thus, the flow restrictor (315) also enables controlled flow of water from the second system (400) into the tank (200).

[0096] FIG. 2c is a block diagram of a second system (400) within a water purification device (WPA) according to one example. In FIG. 2c, the main flow path (1) extends from E to G. In the flow direction along the main flow path (1), the second system (400) includes an inlet valve (401), a pressure sensor (402), a pump (403), a reverse osmosis (RO) unit (404), a flow meter (408), a UV irradiation device (409), a composition sensor (410), a temperature sensor (411), and an outlet valve (412). It will be understood that each of these components provides a specific function in the context of the presented example, but not all components need to be included as shown. For example, any of the components (401 to 403, 408 to 412) may be omitted or placed elsewhere in other examples of the second system (400).

[0097] The inlet valve (401) can be operated via a control signal (VC5) to selectively open and close the main flow path (1) to control the reception of water into the second system (400). The outlet valve (412) ("main outlet valve") can be operated via a control signal (VC6) to selectively open and close the main flow path (1) to control the output of purified water from the second system (400).

[0098] Sensors (402, 408, 410, and 411) each provide measurement signals (P2, F1, C3, T3) indicating water pressure, water flow rate, water temperature, and water composition. The signals (P2, F1, C3, T3) can be used by a control device (500) to control the operation of a water purification device (WPA).

[0099] The reverse osmosis (RO) unit (404) is configured to perform water filtration by reverse osmosis, just like the reverse osmosis (RO) unit (304). In the example presented, the reverse osmosis (RO) unit (404) is permanently installed in the second system (400). In other words, the reverse osmosis (RO) unit (404) is not installed in a way that allows for easy replacement by the user of the water purification device (WPA). As noted above, the reverse osmosis (RO) unit (404) may differ from the reverse osmosis (RO) unit (304) in terms of performance, cost, etc. However, in principle, the reverse osmosis (RO) unit (404) has the configuration shown in FIG. 2d and includes a reverse osmosis (RO) membrane (404'), a feed side (404"), a permeable side (404'"), an inlet port (404A') and an outlet port (404C') on the feed side (404"), and an outlet port (404B') on the permeable side (404'"). The foregoing description of FIG. 2d relating to the reverse osmosis (RO) unit (304) is equally applicable to the reverse osmosis (RO) unit (404). As with the first system (300), a feed pump (403) ("booster pump") is placed in the main flow path (1) to form fluid pressure on the feed side of the reverse osmosis (RO) unit (404). The pumping rate or pumping speed of the feed pump (403) is set by a control signal (PC3). A drain line (2B) is connected to receive wastewater from the reverse osmosis (RO) unit (404). In contrast to the first system (300), the drain line (2B) does not extend to a drain but extends to an inlet port (205) on the tank (200). Thus, wastewater from the reverse osmosis (RO) unit (404) is recirculated back to the tank (200). A flow limiting device ("flow limiter") (406) is placed on the drain line (2B) to maintain a desired fluid pressure on the feed side of the reverse osmosis (RO) unit (404). The flow limiter (406) may be fixed or adjustable.In the example presented, the bypass line (4B) is connected to extend between locations on the drain line (2B) upstream and downstream of the flow restrictor (406). The bypass line (4B) includes a control valve (407) operable to selectively close and open the bypass line (4B) under the influence of a control signal (VC7). Similar to the flow restrictor (306) in FIG. 2b, the flow restrictor (406) can be motorized. By using such a motorized flow restrictor mechanism, the valve (407) and the bypass line (4B) can be omitted. The connection line (3B) is arranged to fluidly connect the drain line (2B) at a location upstream of the flow restrictor (406) to the main flow line (1) at a location between the feed pump (403) and the reverse osmosis (RO) unit (404). Accordingly, as in the first system (300), a water recirculation path or water recirculation loop is formed between the outlet port and the inlet port on the feed side of the reverse osmosis (RO) unit (404). An auxiliary pump ("recirculation pump") (405) is placed within the recirculation path. The pumping rate or pumping speed of the auxiliary pump (405) is set by a control signal (PC4).

[0100] The UV irradiation device (409) may be similar to the UV irradiation device (301) in the first system (300). The UV irradiation device (409) is installed to further reduce microbial activity. The UV irradiation device (409) does not need to be configured to remove chlorine from the influent water, and it will be recognized that there is substantially no chlorine in the influent water at the corresponding location within the water purification device (WPA). By placing the UV irradiation device (409) in the main flow path (1) downstream of the reverse osmosis (RO) unit (404), the UV irradiation device (409) is positioned to operate on water having the lowest content of suspended solids in the water purification device (WPA). Since suspended solids are known to be a limiting parameter related to water treatment by UV irradiation due to the absorption of light by suspended solids and potential shielding of pathogens from light, the above configuration will improve the efficiency of the UV irradiation device (409).

[0101] The return line (5) is fluidly connected to the main flow path (1) between the reverse osmosis (RO) unit (404) and the outlet valve (412). The return line (5) is arranged to enable continuous production of product water (PWA) during the operation of the water purification device (WPA) by allowing excess product water (PWA) to be recirculated back to the tank (200) through the return line (5, 8). To prevent treated water from flowing from the first system (300) along the return line (5) to the second system (400) and potentially mixing with the purified water (PWA), a one-way valve (413) may be placed in the return line (5) as illustrated. In an alternative example, the return line (5) is separate from the return line (8) and extends to the tank (200). In this alternative example, the flow restrictor may be placed in the return line (5) as in the flow restrictor (315) in FIG. 2b to generate net positive pressure in the main flow path (1) at the outlet from the second system (400). In the specific example of FIG. 2c, the return line (5) is fluidly connected to the main flow path (1) downstream of the sensors (408, 410, 411).

[0102] FIG. 3a is a flowchart of a first method (M1) for operating the water purification device (WPA) in FIG. 2a through 2c. The purpose of the first method (M1) is to fill the first system (300) (PS1) with water, and it can be performed whenever the first system (PS1) is empty of water or whenever the first system (PS1) may contain an air pocket, for example, when a new reverse osmosis (RO) unit (304) is installed. It can be seen that the first method (M1) involves "priming" the first system (PS1). While performing the first method (M1), the inlet valve (401) of the second system (400) (PS2) is typically closed so that in the first method (M1), only the first system (PS1) is "primed." In step S11, the UV irradiation device (301) is activated by a control signal (not shown in FIG. 2b). In step S12, the main inlet valve (102) is opened (by the control signal (VC1)), and all pumps are stopped (if active). When the main inlet valve (102) is opened, raw water (SWA) will flow through the pretreatment system (100), and the pretreatment water will enter the tank (200). In step S13, control of the fluid level in the tank (200) is initiated. This level control involves ensuring that the air gap (207) is maintained within the tank (200) based on a signal (L1) from the level sensor (201), and optionally that the water in the tank (200) is not depleted. In one example, while performing the first method (M1), the main inlet valve (102) is closed when the maximum fluid level in the tank (200) is reached, otherwise the main inlet valve (102) is kept open. In step S14, the drain valves (307, 308) in the first system (PS1) are opened (by control signals (VC2, VC3)). In step S15, the feed pump (302) in the first system (PS1) is started (by control signal (PC1)) and operated at speed SM11.By this, a desired fluid pressure is generated on the feed side of the reverse osmosis (RO) unit (304). Permeate begins to flow through the reverse osmosis (RO) membrane (304') into the main flow path (1) downstream of the reverse osmosis (RO) unit (304), and wastewater begins to flow from the reverse osmosis (RO) unit (304) into the drain line (2A) and to the drain (309). In step S16, the recirculation pump (305) in the first system (PS1) is started (by the control signal (PC2)) and operated at speed SR11. By this, a portion of the wastewater is recirculated back into the feed side of the reverse osmosis (RO) unit (304). In step S17, the current operating state of the water purification device (WPA) is maintained during the flushing time interval. The duration of the flushing time interval can be experimentally determined to induce proper charging of the hydraulic circuit of the first system (PS1). Possibly, the tank (200) is filled to the highest fluid level during the flushing time interval. In step S18, after the flushing time interval, the UV irradiation device (301) is deactivated. In step S18, the pumps (302, 305) may also be deactivated. In a non-limiting example, SM11 is set to induce a flow rate of 1000 ml / min and SR11 is set to induce a flow rate of 3000 ml / min, and the flushing time interval is 1 minute to 10 minutes.

[0103] FIG. 3b is a flowchart of a second method (M2) for operating the water purification device (WPA) in FIG. 2a through 2c. The purpose of the second method (M2) is to start the first system (300) (PS1) to produce treated water of appropriate quality. In step S21, the drain valves (307, 308) in the first system (PS1) are opened (by control signals (VC2, VC3)). In step S22, the UV irradiation device (301) is activated. In step S23, level control in the tank (200) is started. In step S24, the return path valve (314) is opened (by control signal (VC4)) and the inlet valve (401) of the second system (400) (PS2) is closed (by control signal (VC5)). In step S25, the feed pump (302) in the first system (PS1) is started and operated at speed SM12. In step S26, the recirculation pump (305) in the first system (PS1) is started and operated at speed SR12. These speeds (SM12, SR12) may be predefined to correspond to the optimal operating point of the first system (PS1). In a non-limiting example, SM12 is set to induce a flow rate of 1500 ml / min, and SR12 is set to induce a flow rate of 4500 ml / min. In step S27, the upstream drain valve (307) is closed (by the control signal (VC2)). In step S28, the operating state of the first system (PS1) is maintained during a stabilization period. The duration of the stabilization period may be experimentally determined to induce stable operation of the reverse osmosis (RO) unit (304). In a non-limiting example, the stabilization period is 1 to 5 minutes. After step S28, the second method (M2) is moved to the third method (M3).

[0104] FIG. 3c is a flowchart of the third method (M3). The purpose of the third method (M3) is to start the second system (400) (PS2) and the water purification device (WPA) accordingly to produce purified water (PWA) of appropriate quality. In step S31, the inlet valve (401) of the second system (PS2) is opened (by the control signal (VC5)) and the UV irradiation device (409) is activated. In step S32, the control device (500) initiates a first control mode to control the feed pump (403) in the second system (PS2) (via the control signal (PC3)) to achieve a first target flow rate (TF1a) at the flow meter (408) as given by the signal (F1). The target flow rate (TF1a) may be the same as the production flow rate of purified water when the water purification device (WPA) is operated, but it does not necessarily have to be. In a non-limiting example, the target flow rate (TF1a) is 500 ml / min. The first control mode involves feedback control. In step S33, the recirculation pump (405) in the second system (PS2) is set to operate at a speed SR21. The speed SR21 may be predefined to correspond to the optimal operating point of the second system (PS2). In a non-limiting example, SR21 is set to induce a flow rate of 2500 ml / min. In step S34, after a waiting period, the return path valve (314) is closed (via the control signal (VC4)) to form an effectively stiff or non-compliant hydraulic path between the feed pump (302) of the first system (PS1) and the flow meter (408) of the second system (PS2). The waiting period may be determined experimentally and may be, for example, 1 to 5 minutes.In step S35, the control device (500) switches from a first control mode to a second control mode, wherein the feed pump (403) in the second system (PS2) is controlled (via a control signal (PC3)) so that a target pressure (TP2) is achieved at the pressure sensor (402) as given by the signal (P2). In a non-limiting example, the target pressure (TP2) is within the range of 0.5 bar to 1 bar. A low target pressure (TP2) tends to increase the risk of cavitation in the feed pump (403), and a high target pressure (TP2) results in high power consumption. The second control mode involves feedback control. In step S36, the control device (500) initiates a third control mode that is executed in parallel with the second control mode. The third control mode involves controlling the feed pump (302) in the first system (PS1) to achieve a second target flow rate (TF1b) at the flow meter (408), as indicated by the signal (F1). The target flow rate (TF1b) is equal to the production flow rate of purified water (PWA) when the water purification device (WPA) is operating. Typically, TF1b is within the range of 200 ml / min to 1500 ml / min. In a non-limiting example, TF1b is 500 ml / min. The third control mode involves feedback control. After step S36, the water purification device (WPA) operates to produce purified water at a constant flow rate. In step S37, if necessary, the temperature of the purified water is controlled by the use of the heater (313) (via the control signal (HC)). This temperature control can be performed by feedback control based on the signal (T3) from the sensor (411). For example, the water temperature can be controlled to fall within a predefined temperature range or to meet a predefined target value. In step S38, the recovery rate of one or both of the reverse osmosis (RO) units (304, 404) can be controlled manually or automatically.As used herein, "recovery rate" refers to the ratio of permeate flow to feed flow and represents the overall operating efficiency of the reverse osmosis (RO) unit. The adjustment in step S38 may involve changing the flow resistance in the drain line (2A, 2B), for example, by operating the corresponding flow restrictor (306, 406). In step S39, the performance of the reverse osmosis (RO) unit (304, 404) is checked by evaluating one or more operating parameters. The operating parameters may include one or more of the composition, temperature, or flow rate of the purified water (PWA), each given by signals (C3, T3, and F1). Additionally, the pressure of the purified water (PWA) may be monitored by a pressure sensor (not shown) downstream of the reverse osmosis (RO) unit (404) in the second system (400). If it is found that at least one operating parameter deviates from a preset value or preset range, step S39A proceeds to step S39C, where the operating error is signaled to the user, for example, by an HMI device (503 in FIG. 1). If no deviation is found, step S39A proceeds to step S39B, in which the main outlet valve (412) is opened or the main outlet valve (412) is at least enabled for opening. When enabled for opening, the control device (500) will respond to a command from a downstream receiving device to open the valve (412). In a non-limiting example, where the composition is given by conductivity, step S39A may require that the conductivity of the purified water (PWA) be less than 20 μS / cm.

[0105] It is realized that the recirculation pumps (305, 405) operate at a constant speed during the operation of the water purification device (WPA), while the feed pumps (302, 403) are individually controlled by the control device (500). The feed pump (302) in the first system (PS1) is controlled to achieve a target flow rate (TF1b) of the purified water (PWA), and the feed pump (403) in the second system (PS2) is controlled to achieve a target pressure (TP2) at the inlet of the feed pump (403). This control method has been found to lead to stable operation of the water purification device (WPA). Furthermore, cavitation in the feed pump (403) is actively prevented.

[0106] During the operation of the water purification device (WPA), the control device (500) may be configured to monitor performance parameters of the replaceable reverse osmosis (RO) unit (304) to identify whether there is a need to replace the reverse osmosis (RO) unit (304) now or in the future. These performance parameters may represent the flow resistance of the membrane (304') within the reverse osmosis (RO) unit (304) directly or indirectly. One exemplary performance parameter is given by the pressure measured by the pressure sensor (303). Another exemplary performance parameter is given by the power consumption of the feed pump (302), for example, by the driving current or driving voltage supplied to the feed pump (302). Another performance parameter may be given by the flow rate measured by a flow meter (not shown) placed in the main flow path (1) downstream of the reverse osmosis (RO) unit (304) in the first system (PS1).

[0107] FIG. 3d is a flowchart of the fourth method (M4). The purpose of the fourth method (M4) is to terminate the operation of the water purification device (WPA) in a well-controlled manner. In step S41, the main outlet valve (412) is closed and / or disabled for opening. In step S42, the feed pumps (302, 403) are stopped. In step S43, the recirculation pumps (305, 405) are stopped. Step S43 may be performed with a time delay from step S42. In a non-limiting example, this time delay may be from 1 minute to 5 minutes. In step S44, the inlet valve (401) of the second system (PS2) is closed. In step S45, the UV irradiation device (301, 409) is deactivated.

[0108] The embodiments described above with reference to FIGS. 1 through 3 embody a number of basic concepts. These concepts will be described individually below with reference to FIGS. 4 through 12. Each concept provides its own specific technical advantages and can be implemented in a water purification device (WPA) alone or in combination with one or more other concepts. As can be understood from the foregoing description regarding FIGS. 1 through 3 as well as the description below, unique synergies will also be achieved by combining the concepts in the water purification device (WPA).

[0109] As indicated by dashed lines in FIGS. 4a, FIGS. 6, FIGS. 7, FIGS. 8a, FIGS. 9a, FIGS. 10a, FIGS. 11, and FIGS. 12, a pretreatment system (100) may be placed upstream of the first system (300) to perform, for example, dechlorination of raw water (SWA). The pretreatment system (100) may have any function as previously described with reference to FIGS. 1 and FIGS. 2a.

[0110] FIG. 4a is a block diagram of an exemplary water purification device (WPA) implementing a first concept. In the first concept, the water purification device (WPA) includes a main flow path (1) extending from a main water inlet (1') for raw water (SWA) to a main water outlet (1") for product water (PWA). A first system (300) is positioned in the main flow path (1) and configured to treat the influent water to reduce water hardness, thereby obtaining treated water with reduced water hardness. The first system (300) includes a first reverse osmosis (RO) unit (304) for use in treating the influent water. A second system (400) is positioned in the main flow path (1) between the first system (300) and the main water outlet (1"). The second system (400) is configured to receive treated water from the first system (300) and further treat this treated water into purified water (PWA). The second system (400) includes a second reverse osmosis (RO) unit (404) for use in treating treated water from the first system (300). A specific feature of the first concept is that the first reverse osmosis (RO) unit (304) is a sacrificial component that is detachably installed in the first system (300).

[0111] Accordingly, according to the first embodiment, the water purification device (WPA) comprises two reverse osmosis (RO) units (304, 404), and these reverse osmosis (RO) units are arranged sequentially so that the downstream (second) reverse osmosis (RO) unit (404) receives and treats (purifies) the treated water (permeate) from the upstream (first) reverse osmosis (RO) unit (304), which is a sacrificial / disposable component.

[0112] The corresponding reverse osmosis (RO) unit (304, 404) can be configured according to FIG. 2d.

[0113] When used herein, "sacrificial component" means that the component has a limited lifespan and is intended to be discarded and replaced with a new component when its lifespan ends. Thus, in the first concept, the reverse osmosis (RO) unit (304) is disposable.

[0114] Generally, a reverse osmosis (RO) unit (304) is placed in the water purification unit (WPA) so that it is accessible for replacement by an untrained user. An untrained user is distinguished from service technicians, etc., who have received extensive training in how to perform maintenance, service, and inspection of the water purification unit (WPA) by typically disassembling or taking apart the unit. The untrained user may be a patient or a caregiver. Thanks to the replacement-friendly design of the water purification unit (WPA), the replacement of the reverse osmosis (RO) unit (304) can be performed locally at the location where the water purification unit (WPA) is installed for use, and is typically performed at the location where the water purification unit (WPA) is installed for use. In other words, such replacement is performed at the point of care. As used herein, the "point of care" is, for example, the place where medical services are received at the patient's home, clinic, or hospital.

[0115] In FIG. 4a, the reverse osmosis (RO) unit (304) is detachably installed by a releaseable connector (304A, 304B, 304C) connected to a corresponding port on the reverse osmosis (RO) unit (304) (see 304A', 304B', 304C' in FIG. 2d). The releaseable connector (304A to 304C) may be any suitable type for quick release, such as a screw fitting, a bayonet fitting, a snap fitting, a luer fitting, etc. The water purification device (WPA) may be configured to simplify replacement of the reverse osmosis (RO) unit (304) by providing the user with easy access to the reverse osmosis (RO) unit (304) and the connector (304A to 304C). For example, the water purification device (WPA) may include a housing with a dedicated door or hatch, which, when opened, provides free access to the reverse osmosis (RO) unit (304) for the user. Furthermore, the water purification device (WPA) may be configured to provide step-by-step instructions on an HMI device (503 in FIG. 1) for an untrained user regarding a method of removing the reverse osmosis (RO) unit (304) from the water purification device (WPA) and installing a new reverse osmosis (RO) unit (304) in the appropriate place.

[0116] One technical advantage of configuring the first reverse osmosis (RO) unit (304) as a sacrificial component is that the water purification device (WPA) can be intentionally operated during normal operation to sacrifice the first reverse osmosis (RO) unit (304) in order to protect the downstream second reverse osmosis (RO) unit (404) in the second system (400). For example, as discussed with reference to the water purification device (WPA) in FIGS. 1 through 3, the first reverse osmosis (RO) unit (304) can be operated to reduce the water hardness of the influent water so that the resulting treated water is softened sufficiently to alleviate scaling of the second system (400). This means that substances contributing to water hardness are captured by the reverse osmosis (RO) membrane (304') of the first reverse osmosis (RO) unit (304), causing relatively rapid deterioration of the reverse osmosis (RO) membrane (304'). This deterioration is likely to be at least partially irreversible, that is, it persists even when the reverse osmosis (RO) membrane (304') undergoes a cleaning procedure.

[0117] Another advantage of using a sacrificial reverse osmosis (RO) unit (304) is that the need to configure a water purification unit (WPA) to perform regular cleaning of the reverse osmosis (RO) unit (304) can be reduced or even eliminated. Thus, the structure of the water purification unit (WPA) can be simplified.

[0118] Furthermore, by replacing the reverse osmosis (RO) unit (304), the need for service and maintenance of the entire water purification unit (WPA) can be reduced based on appropriate criteria. Such criteria for replacement may be given by the time since the last replacement, the effective operating time since the last replacement, as discussed below with reference to FIGS. 9a and 9b, for example, or based on the measured quality of the product water (PWA) or performance parameters measured for the reverse osmosis (RO) unit (304).

[0119] The first reverse osmosis (RO) unit (304) may be configured to have a predetermined target lifespan when installed in the water purification device (WPA). This means that the first reverse osmosis (RO) unit (304) will not need to be replaced within its target lifespan. For example, the target lifespan may be given in terms of the amount of treated water that can be produced by the reverse osmosis (RO) unit (304), that is, in terms of the total production volume of purified water by the first reverse osmosis (RO) unit (304). In some embodiments, the target lifespan is at least 20,000 L or 25,000 L and 90,000 L or 100,000 L or less. For target lifespans falling within this range, the reverse osmosis (RO) unit (304) is simple enough to allow for reasonable operating costs of the water purification device (WPA) and is accordingly inexpensive. In addition, the above target lifespan allows the water purification device (WPA) to operate for a reasonable period of time before the reverse osmosis (RO) unit (304) needs to be replaced. Assuming that 50 L of purified water (PWA) is consumed per day by PD treatment, calculations show that a target lifespan of 25,000 L corresponds to approximately 6 months of PD treatment. Since this usage period is proportional to the target lifespan, if the target lifespan is doubled, the usage period is also doubled. In another example, Continuous Renal Replacement Therapy (CRRT) is assumed to consume 500 L of purified water (PWA) per day. Similar to the example above, a target lifespan of 25,000 L corresponds to approximately 18 days of CRRT treatment.

[0120] In some embodiments, the target life is within the range of 40,000 L to 70,000 L.

[0121] A target life is realized by being defined for the nominal or standard operating conditions of the reverse osmosis (RO) unit (304). In some embodiments, the nominal operating conditions involve an influent having a hardness of 450 ppm (mgCaCO3 / L) and / or a conductivity of 2,000 μS / cm and a flow rate of 1 L / min of treated water. The target life may be defined to ensure that the permeate from the reverse osmosis (RO) unit (304) satisfies one or more water quality parameters during the target life, for example, in terms of water hardness, conductivity, or microbial load, or any combination thereof. For example, the target life may be defined so that the treated water has a hardness of less than 30 ppm (mgCaCO3 / L) and / or a conductivity of less than 50 μS / cm.

[0122] In some embodiments, the water purification device (WPA) is configured to operate a replaceable reverse osmosis (RO) unit (304) without thermal sterilization of the reverse osmosis (RO) membrane (304') for a target life. For example, the reverse osmosis (RO) unit (304) may be configured for a maximum fluid temperature of 40°C, 50°C, or 60°C. Thus, the reverse osmosis (RO) unit (304) does not need to be configured to withstand temperatures exceeding the maximum fluid temperature. Such a reverse osmosis (RO) unit is much cheaper than a reverse osmosis (RO) unit configured to withstand higher temperatures, for example, by 5 to 10 times.

[0123] In some embodiments, the water purification device (WPA) is configured to operate a replaceable reverse osmosis (RO) unit (304) without cleaning, disinfecting, or sterilizing the reverse osmosis (RO) membrane (304') by the application of a cleaning agent and / or heat for a target life. As used herein, “cleaning” is performed to remove sediment, “sterilization” is performed to remove bacteria, and “disinfection” is performed to remove both bacteria and viruses.

[0124] In the example of FIG. 4a, the second reverse osmosis (RO) unit (404) is permanently installed in the second system (400). This enables the use of the high-end reverse osmosis (RO) unit (404) in the second system (400). By using the high-end reverse osmosis (RO) unit (404) with high-end performance, the requirements for the first reverse osmosis (RO) unit (404) are relaxed. Thus, symbiosis is achieved between the reverse osmosis (RO) units (304, 404), wherein the first reverse osmosis (RO) unit (304) is provided with consideration for the use of the high-performance and high-quality second reverse osmosis (RO) unit (404), and this type of second reverse osmosis (RO) unit (404) is provided with consideration for the use of the simpler first reverse osmosis (RO) unit (304) as a sacrificial component.

[0125] The water purification device (WPA) may be configured to perform cleaning, sterilization, or disinfection of the reverse osmosis (RO) membrane (404') of the second reverse osmosis (RO) unit (404) by the use of a cleaning agent and / or the application of heat.

[0126] As can be seen from FIGS. 1 to 3, the water purification device (WPA) may include additional components. For example, as shown in FIG. 4a, a feed pump (302) may be placed in the main flow path (1) upstream of the first reverse osmosis (RO) unit (304) to increase the pressure of the inflow water to the reverse osmosis (RO) unit (304). Although not shown in FIG. 4a, a feed pump (e.g., 403 in FIG. 2c) corresponding to the upstream of the second reverse osmosis (RO) unit (404) may be placed in the second system (400).

[0127] FIG. 4b is a flowchart of a method (M5) illustrating the operation of a water purification device (WPA) for replacing a first reverse osmosis (RO) unit (304). This method (M5) can be performed by the control device (500) in FIG. 1. In the method (M5), for example, when the criteria for replacement are met as previously illustrated, the user is commanded to remove the reverse osmosis (RO) unit (304) from the water purification device (WPA). The user may receive the command on an HMI device (503 in FIG. 1). The method (M5) includes the step (S51) of commanding the user to disconnect and remove the reverse osmosis (RO) unit (304) from the first system (300) (indicated as PS1 in FIG. 4b). In step S53, the user is commanded to install a new reverse osmosis (RO) unit (304) in the first system (300). The completion of step S53 and the subsequent installation of a new reverse osmosis (RO) unit (304) may be automatically detected by a control device (500) and / or confirmed by user input through an HMI device. Automatic detection of the aforementioned installation may utilize any type of detection system to detect the connection of the reverse osmosis (RO) unit following the disconnection of the reverse osmosis (RO) unit, for example, by a computer vision device or by the use of electrical contacts within the connectors (304A to 304C) and the ports (304A' to 304C') of the reverse osmosis (RO) unit (304). Furthermore, after the detection of such installation, a test may be performed to verify one or more characteristics of the reverse osmosis (RO) unit (304), as described below with reference to FIGS. 9a and 9b, for example. Accordingly, the water purification device (WPA) is prepared to be started, for example, by method (M1, M2, or M3) (Figs. 3a to 3c) or a combination thereof.In step S54, the water purification device (WPA) is operated to produce purified water (PWA) having the required characteristics, such as a conductivity of less than 20 μS / cm. As previously mentioned, the purified water (PWA) may satisfy some or all of the requirements for "water for dialysis."

[0128] FIG. 5 is a block diagram of a first reverse osmosis (RO) unit (304) implementing a second concept. In the second concept, the main flow path (1) includes a feed line (1A) extending to a water inlet (304A') on the feed side (304") of the reverse osmosis (RO) unit (304), said reverse osmosis (RO) unit may or may not be a sacrificial component. The first system (300) includes a feed pump (302) placed in the feed line (1A) to pressurize the inflow water at the water inlet (304A'). The first system (300) further includes a drain line (2A) extending from a residual outlet (304C') on the feed side (304") of the reverse osmosis (RO) unit (304). A flow limiting device (306) is placed in the drain line (2A) to form a flow resistance at the residual outlet (304C') on the feed side (304") of the reverse osmosis (RO) unit (304). The flow limiting device (306) is included to maintain a desired fluid pressure on the feed side (304") of the reverse osmosis (RO) unit (304). The flow limiting device (306) may be configured to have a constant flow resistance or to allow the flow resistance to be varied. In some embodiments, the flow limiting device (306) is a variable orifice valve. In some embodiments, the flow limiting device (306) is operable to change the flow resistance based on a control signal. In some embodiments, the flow limiting device (306) is electrically controllable and is powered by a control signal generated by a control device (500) (Fig. 1a) and indicated as FC1 in Fig. 5. In some embodiments, as illustrated, the flow limiting device (306) is supplemented by a bypass path (4A) including an on / off valve (307). The bypass path (4A) is connected to a drain line (2A) on both sides of the flow limiting device (306).The purpose of the on / off valve (307) is to enable a high flow rate through the feed side (304) when, for example, during priming, the high flow rate is not supported by the flow limiting device (306). Accordingly, the on / off valve (307) can be selectively opened under the influence of a control signal (see VC2 in FIG. 2b).

[0129] In some embodiments, as illustrated in FIG. 5, the first system (300) further includes a connection line (3A) arranged to be in fluid communication with the drain line (2A) and the feed line (1A) to form a recirculation path from the residual outlet (304C') to the water inlet (304A'). An auxiliary pump ("recirculation pump") (305) is placed in the recirculation path to provide additional flow on the flow path (see FP2 in FIG. 2d) following the reverse osmosis (RO) membrane (304') on the feed side (304") of the reverse osmosis (RO) unit (304). Providing this recirculation loop reduces the amount of water discarded to the drain. Other advantages and features of the recirculation path and the recirculation pump (305) have been discussed with reference to FIG. 2b and will not be mentioned again. In the example presented, the recirculation pump (305) is placed in the connection line (3A).

[0130] It should be noted that the degree of flow resistance implemented by the flow limiting device (306) by affecting the fluid pressure on the feed side (304) affects the flow rate of treated water from the reverse osmosis (RO) unit (304). On the other hand, the recirculation pump (305) has little to no effect on the fluid pressure on the feed side (304), but rather affects the flow rate of water through the feed side (304).

[0131] Although the second concept is presented for the first reverse osmosis (RO) unit (304) in FIG. 5, it is equally applicable to the second reverse osmosis (RO) unit (404).

[0132] FIG. 6 is a block diagram of an exemplary water purification device (WPA) implementing a third concept. In the third concept, the water purification device (WPA) includes a main flow path (1) extending from a main water inlet (1') for raw water (SWA) to a main water outlet (1") for product water (PWA). A first system (300) is positioned in the main flow path (1) and configured to treat the influent water to reduce water hardness, thereby obtaining treated water with reduced water hardness. The first system (300) includes a first reverse osmosis (RO) unit (304) for use in treating the influent water. A second system (400) is positioned in the main flow path (1) between the first system (300) and the main water outlet (1"). The second system (400) is configured to receive the treated water from the first system (300) and further treat this treated water into product water (PWA). The second system (400) may use any suitable water treatment technique, such as reverse osmosis and / or ion exchange. A specific feature of the third concept is a recirculation path (5) arranged to recirculate the product water (PWA) generated by the second system (400) back to the first system (300) and / or the second system (400). In the example presented, the flow of product water (PWA) along the main flow path (1) and in the recirculation path (5) is generated by the feed pump (302) in the first system (300). By recirculating the product water (PWA), it is possible to operate the water purification device (WPA) to continuously generate product water (PWA) at a predefined flow rate, even if a downstream device (not shown) obtains product water (PWA) from the water purification device (WPA) at a lower flow rate and / or intermittently. Continuous operation will ensure consistent quality of the generated Product Water (PWA).In contrast, if the Product Water Amount (PWA) generation rate of the Water Purification Unit (WPA) needs to be modified according to the needs of downstream devices, the quality of the generated PWA may vary as a result of transient effects. This can be mitigated by discarding the initial PWA generated whenever the generation rate is modified. However, this can lead not only to significant water waste but also to longer response times for the Water Purification Unit (WPA).

[0133] In the example presented, the water purification device (WPA) includes an outlet valve (412), which is selectively opened by a control device (500) (Fig. 1) to provide product water (PWA) to a downstream device. The outlet valve (412) may, instead, be part of the downstream device or be controlled by the downstream device.

[0134] In some embodiments, as indicated by the solid arrow in FIG. 6, the recirculation path (5) extends from a first location in the main flow path (1) downstream of the second system (400) to a second location in the main flow path (1) upstream of the first system (300). Thus, the recirculated product water (PWA) is included in the inflow water to the first system (300), which can limit the influence of the recirculated product water (PWA) on the operation of the second system (400). As understood from the embodiments in FIG. 1 to 3, it may be beneficial to recirculate excess product water (PWA) through a tank (200 in FIG. 2a) placed in the main flow path (1) upstream of the first system (300). According to this, the operation of the first system (300) and the second system (400) will be further decoupled from the recirculation of excess product water (PWA).

[0135] In some embodiments, as indicated by reference numeral 6 in FIG. 6, the recirculation path extends instead from a first location to a third location between the first system (300) and the second system (400) in the main flow path (1). A tank (not shown) may be placed between the first system (300) and the second system (400) in the main flow path (1) to receive the recirculated product water (PWA). Additionally, the tank may receive treated water from the first system (300).

[0136] In some embodiments, the recirculation path extends from a first position to both a second position and a third position.

[0137] As illustrated in FIG. 6, the recirculation path may include a flow limiting device (315). One purpose of the flow limiting device (315) is to ensure a desired fluid pressure at the main water outlet (1"). This is relevant whenever the pressure at a second or third location at the end of the recirculation path is significantly lower than the desired fluid pressure at the main water outlet (1"). In the example of FIG. 1 through 3, the recirculation path extends to a tank (200) at atmospheric pressure, and the flow limiting device (315) is positioned to establish a higher fluid pressure at the main water outlet (1"). Additionally, the flow limiting device (315) may serve to provide a more controlled flow in the recirculation path. The flow limiting device (315) may be configured to have a constant flow resistance or to allow the flow resistance to be varied.

[0138] FIG. 7 is a block diagram of an exemplary water purification device (WPA) implementing the fourth concept. In the example presented, the components along the main flow path (1) may be the same as those in the first concept (Fig. 1) and will not be described again. It should be noted that the first reverse osmosis (RO) unit (300) may be a sacrificial component, but is not necessarily so. In the example presented, the tank (200) is placed upstream of the first system (300) to receive raw water (SWA) after pretreatment by the pretreatment system (100), optionally. A specific feature of the fourth concept is that the drain path (2B) from the second reverse osmosis (RO) unit (404) is fluidly connected to the main flow path (1) at an upstream location of the first system (300), and accordingly, wastewater ("residue") from the second reverse osmosis (RO) unit (400) is returned for treatment by the first system (300) and the second system (400). This will increase the efficiency of the water purification device (WPA) by reducing the amount of wastewater discharged to the drain. The underlying theoretical basis is that since the majority of impurities are removed by the first system (300), the wastewater from the second reverse osmosis (RO) unit (404) contains a relatively small amount of impurities. Therefore, recycling the wastewater from the second system (400) will have almost no negative effect on the operation of the first system (300). For example, since the second system (400) operates on water softened by the first system (300), recycling wastewater from the second system (400) will not increase scaling of the reverse osmosis (RO) membrane (304'). Therefore, the lifespan of the reverse osmosis (RO) membrane (304') is not significantly affected by this recycling. It should be noted that in the example of FIG. 7, wastewater from the first system (300) is not recycled. The drain line (2A) from the first system (300) can be extended to the drain.In a modified example, a portion of the wastewater from the first system (300) can also be recycled, as described with reference to the example of FIG. 5.

[0139] As can be seen in FIG. 7, the drain line (2B) may include a flow limiting device (406) corresponding to the flow limiting device (306) in FIG. 5 and also included to maintain a desired fluid pressure on the feed side of the reverse osmosis (RO) unit (404).

[0140] As illustrated, by connecting the drain line (2B) to the tank (200), the operation of the first system (300) and the second system (400) is decoupled from the recirculation of wastewater. Furthermore, recirculation into the tank (200) can facilitate the mixing of wastewater into the raw water (SWA). However, the drain line (2B) may be extended to another location within the main flow path (1) upstream of the first system (300), for example, as indicated by the dashed arrow (7). Furthermore, the tank (200) may be omitted.

[0141] FIG. 8a is a block diagram of an exemplary water purification device (WPA) implementing the fifth concept. In the example presented, the components following the main flow path (1) may be the same as those in the third concept (Fig. 6), and will not be described again. A specific feature of the fifth concept is that the main flow path (1) at a location between the first system (300) and the second system (400) is connected for fluid communication with the main flow path (1) at a location upstream of the first system (300). This allows the treated water generated by the first system (300) to be recirculated back to the first system (300). This recirculation can be utilized during the startup of the water purification device (WPA) to allow the first system (300) to be started independently of the second system (400). This will consequently lead to a controlled startup procedure for the water purification device (WPA). For example, the time required to reach steady-state operation of the water purification device (WPA) can be minimized. Furthermore, the first system (300) may generate inferior quality treated water during startup, and this recirculation will prevent the second system (400) from being exposed to such treated water. This will, for example, reduce the risk of scaling in the second system (400).

[0142] The fifth concept may be particularly useful in ensuring that, when the first reverse osmosis (RO) unit (304) is a sacrificial component, the newly installed first reverse osmosis (RO) unit (304) is properly charged ("primed") with water and operates to produce treated water of appropriate quality before the treated water is received into the second system (400).

[0143] In the example presented, the return flow path (8) is arranged to fluidly connect the main flow path (1) at the junction between the first system (300) and the second system (400) to the feed side of the first reverse osmosis (RO) unit (304) ("304" in FIG. 2d). A combination of on / off valves (314, 401) forms a valve device capable of switching between guiding treated water from the first system (300) to the second system (400) on the main flow path (1) and guiding treated water to the feed side of the reverse osmosis (RO) unit (304) on the return flow path (8). In the example presented, the on / off valve (314) is arranged in the return flow path (8), and the on / off valve (401) is arranged in the main flow path (1) downstream of the junction of the return flow path (8). The on / off valves (314, 401) are controlled by a control device (in FIG. 5 It can be operated by a control signal from 500). It will be recognized that other embodiments of the valve device can be conceived, for example, as a single three-way valve.

[0144] In the example presented, the sensor (311) is positioned in the main flow path (1) between the first system (300) and the junction of the return flow path (8). The sensor (311) is configured to generate a sensor signal (C2) for a parameter indicating the operation of the first system (300), such as pressure, temperature, flow rate, etc. In some embodiments, the sensor signal (C2) indicates a parameter related to the composition of the treated water. In some embodiments, the composition-related parameter corresponds to electrical conductivity.

[0145] In the example presented, the feed pump (302) is positioned within the main flow path (1) upstream of the first reverse osmosis (RO) unit (304). The return flow path (8) extends to a position on the main flow path (1) upstream of the feed pump (302), and accordingly, the suction generated by the feed pump (302) drives the recirculation of the treated water.

[0146] Although not illustrated in FIG. 8a, a tank that can be placed in the main flow path (1) upstream of the first system (300) can receive treated water from the return flow path (8). Additionally, the tank can be optionally placed to receive raw water (SWA) after pretreatment by the pretreatment system (100).

[0147] FIG. 8b is a flowchart of an exemplary method (M6) for starting the water purification device (WPA) in FIG. 8a. This method (M6) can be performed by the control device (500) in FIG. 1. In step S61, valves (314, 401) are operated to open the return flow path (8) and close the main flow path (1) between the first system (300) (indicated as PS1 in FIG. 8b) and the second system (400) (indicated as PS2 in FIG. 8b). In step S62, the feed pump (302) is started and operated at a predefined first operating point (OP1). By this, treated water is generated at a constant flow rate and recirculated back to the inlet of the reverse osmosis (RO) unit (304). In step S63, based on the sensor signal (C2), the value of one or more state parameters for the first system (300) is determined. In step S64, the value from step S63 is evaluated in relation to a predefined criterion that defines the acceptable characteristics of the treated water. For example, step S64 can verify that the measured conductivity is below a predefined conductivity limit. If the evaluation in step S64 is positive, the method proceeds to step S65, in which the valve (314, 401) is operated to open the main flow path (1) and close the return flow path (8). Thus, the flow of the treated water is switched toward the second system (400). In step S66, the second system (400) is started and operated at a predefined second operating point (OP2). If the evaluation in step S64 is negative, the method proceeds to step S67 to check whether the maximum time has elapsed since step S62. Otherwise, the method optionally proceeds to step S63 after the waiting time in step S68. If the maximum time has elapsed, the startup procedure may be terminated, and an error signal may be generated in step S69 to warn the operator that the startup procedure has failed.

[0148] In steps S63, S64, S67, and S68, when the feed pump (302) is operated for a certain time interval, the treated water from the first system (300) is switched toward the second system (400). In the example of FIG. 8b, this time interval is given by measurement. In a variation, the time interval is predefined.

[0149] In a modified example, the valve device can be controlled to open both the main flow path (1) and the return flow path (8) in step S65, and accordingly, the treated water is supplied to the second system (400) and also recirculated back to the first system (300).

[0150] FIG. 9a is a block diagram of an exemplary water purification device (WPA) implementing the sixth concept. In the example presented, the components following the main flow path (1) may be the same as those in the third concept (Fig. 6), and will not be described again. The first reverse osmosis (RO) unit (304) is a sacrificial component configured for replacement, as indicated by the connectors (304A to 304C). A specific feature of the sixth concept is a monitoring device (510) configured to determine a performance parameter representing the flow resistance through the first reverse osmosis (RO) unit (304) and to evaluate said performance parameter to detect the need to replace the first reverse osmosis (RO) unit (304). said flow resistance represents the degree of contamination of the reverse osmosis (RO) membrane (304'). The monitoring device (510) may be included in the control device (500) (Fig. 1) or may be a separate device. As described, the water purification device (WPA) may include a pressure sensor (303) placed in the main flow path (1) upstream of the reverse osmosis (RO) unit (304) to generate a pressure signal (P1) indicating the fluid pressure on the feed side of the reverse osmosis (RO) unit (304). For example, if the flow rate of water through the reverse osmosis (RO) unit (304) is constant, the fluid pressure on the feed side will increase as the flow resistance through the reverse osmosis (RO) unit (304) increases. Alternatively, or additionally, the water purification device (WPA) may include a flow meter (320) placed in the main flow path (1) between the first system (300) and the second system (400) to generate a flow signal (F2) indicating the flow rate of treated water from the first system (300). The flow rate of treated water from the first system (300) will decrease as the flow resistance through the reverse osmosis (RO) unit (304) increases. Likewise, as the flow resistance through the reverse osmosis (RO) unit (304) increases, the power consumption of the feed pump (302) will increase.This power consumption may be represented by a signal (E1) that may indicate the driving current or driving voltage of the feed pump (302). The signal (E1) is generated by a power sensor (321) that may be located in a joint position with the feed pump (302) as illustrated or included in the monitoring device (510). The power sensor (321) may be positioned to measure the electric driving current supplied to the motor within the feed pump (302) or the electric driving voltage applied to the motor during the operation of the feed pump (302). As shown in FIG. 9a, the monitoring device (510) may be configured to operate on at least one of the signals (E1, P1, F2) to evaluate the condition of the reverse osmosis (RO) membrane (304') and output a filter status signal (FSS).

[0151] FIG. 9b is a flowchart of an exemplary method (M7) for operating the monitoring device (510) in FIG. 9a. The method (M7) may be performed continuously or intermittently during the operation of the water purification device (WPA). In step S71, measurement data representing at least one of feed-side pressure (signal P1), downstream flow rate (signal F2), or feed pump power (signal E1) is obtained. In step S72, the measurement data is evaluated in relation to a predefined standard. For example, one or more performance parameters may be determined from the measurement data and compared to an acceptable range. This acceptable range may be determined to ensure proper operation of the reverse osmosis (RO) unit (304). If outside the acceptable range, an increased risk may occur, such as damage or failure of the reverse osmosis (RO) membrane (304'), power consumption of the feed pump (302), and noise. In the example of step S72, the feed-side pressure or feed-pump power may be compared to an acceptable maximum limit, or the downstream flow rate may be compared to an acceptable minimum limit. If the corresponding performance parameters are within an acceptable range, the method optionally returns to step S71 (by step S73) after the waiting time in step S74. Otherwise, step S75 is performed to indicate the need to replace the reverse osmosis (RO) unit (304) via the signal FSS.

[0152] As an alternative or supplement to the above method (M7), when the reverse osmosis (RO) unit (304) has been installed for a predetermined time, used for a predetermined time, or operated to produce a predetermined amount of treated water, the need to replace the reverse osmosis (RO) unit (304) may be signaled.

[0153] FIG. 10a is a block diagram of an exemplary water purification device (WPA) implementing the seventh concept. In the seventh concept, the water purification device (WPA) comprises a main flow path (1) extending from a main water inlet (1') for raw water (SWA) to a main water outlet (1") for product water (PWA). A first system (300) is placed in the main flow path (1) and configured to treat the influent water to reduce water hardness, thereby obtaining treated water with reduced water hardness. The first system (300) comprises a first reverse osmosis (RO) unit (304) for use in treating the influent water, and a first feed pump (302) for feeding the influent water to the first reverse osmosis (RO) unit (304). The first reverse osmosis (RO) unit (300) may be a sacrificial component, but is not required to be so. A second system (400) is placed in the main flow path (1) between the first system (300) and the main water outlet (1"). The second system (400) is configured to receive treated water from the first system (300) and further process this treated water into product water (PWA). The second system (400) includes a second reverse osmosis (RO) unit (404) for use in treating the treated water from the first system (300), and a second feed pump (403) for feeding the treated water to the second reverse osmosis (RO) unit (404). A flow meter (408) is positioned to provide a sensor signal (F1) indicating the flow rate of the product water (PWA) generated by the second system (400). A pressure sensor (402) is positioned to provide a sensor signal (P2) indicating the pressure of the inlet of the treated water at the second feed pump (403). A specific feature of the seventh concept is a first controller (511) configured to generate a first control signal (PC1) for a first feed pump (302) based on a sensor signal (F1), and a second controller (512) configured to generate a second control signal (PC3) for a second feed pump (403) based on a sensor signal (P2).The first controller (511) and the second controller (511, 512) may be included in the control device (500) of FIG. 1. It has been found that providing the first controller (511) and the second controller (512) provides simple and stable control of the water purification device (WPA) by providing individual control of the first feed pump (302) and the second feed pump (403). In other words, the first controller (511) and the second controller (512) operate independently of each other in the sense that these controllers operate on different input variables and control different pumps.

[0154] The first feed pump (302) is controlled by the first controller (511) to achieve a well-defined flow rate of product water (PWA) from the second system (400). The second controller (512) is positioned to achieve an appropriate inlet pressure of the second feed pump (403) to ensure proper operation of the second feed pump (403). If the inlet pressure of the second feed pump (403) is too low, there is a risk of cavitation occurring in the second feed pump (403). As the inlet pressure of the second feed pump (403) increases, the power consumption of the water purification device (WPA) increases rapidly through the increased power consumption of the first system (300) to achieve the increased inlet pressure of the second feed pump (403). Furthermore, excessive inlet pressure of the second feed pump (403) can cause uncontrolled pressure pulsations in the hydraulic system of the water purification device (WPA).

[0155] In some embodiments, as illustrated in FIG. 10a, the first controller (511) is configured to generate a first control signal (PC1) to achieve a target flow rate (TF1b) of product water (PWA) in the flow meter (408). In some embodiments, TF1b is in the range of 100 ml / min to 2000 ml / min, for example, in the range of 200 ml / min to 1500 ml / min.

[0156] In some embodiments, as illustrated in FIG. 10a, the second controller (512) is configured to generate a second control signal (PC3) to achieve a target inlet pressure (TP2) of the treated water in the second feed pump (403). The applicant has found that if TP2 > 0 bar (atmospheric pressure), the risk of cavitation is mitigated. Furthermore, the applicant has found that if TP2 < 1 bar, it results in acceptable power consumption and mitigates the occurrence of uncontrolled pressure pulsations. Currently, it is determined that desirable performance is achieved using a TP2 in the range of 0.1 bar to 0.9 bar.

[0157] In the example of FIG. 10a, the flow meter (408) is positioned within the main flow path (1) between the second reverse osmosis (RO) unit (404) and the water outlet (1"). When the seventh concept is combined with the recirculation of the third concept (Fig. 6), the flow meter (408) is positioned upstream of the recirculation line, that is, between the second system (400) and the junction of line (5) in FIG. 6, to monitor the entire flow of product water (PWA) generated by the second system (400). The flow meter (408) may be based on any conventional measurement technique, such as a mechanical technique, a pressure-based technique, a variable area-based technique, an optical technique, an electromagnetic technique, an ultrasonic technique, a Coriolis-based technique, a thermal-mass-based technique, or a vortex-based technique.

[0158] In the example of FIG. 10a, the pressure sensor (402) is positioned in the main flow path (1) upstream of the second feed pump (403). The pressure sensor may be a conventional configuration that operates, for example, by resistive sensing, capacitive sensing, inductive sensing, magnetic sensing, or optical sensing, and by using one or more diaphragms, bellows, Bourdon tubes, piezoelectric components, semiconductor components, strain gauges, resonant wires, accelerometers, etc.

[0159] The applicant has discovered that when the water purification device (WPA) is operated to generate product water (PWA), the performance of the control unit according to the seventh concept is improved when the hydraulic system between the feed pump (302) and the flow meter (408) is "stiff." In this context, "stiff" means that there is no compliance in the hydraulic system. In other words, the hydraulic system is configured such that a predefined change in the flow rate by the feed pump (302) causes a decisive change in the flow rate at the flow meter (408), assuming that the flow resistance through the reverse osmosis (RO) unit (304) remains constant. Such a hydraulic system is presented in the example of FIG. 10a, assuming that all fluid lines are not deformed under the relevant operating conditions. Those skilled in the art will understand that even if wastewater is diverted from the reverse osmosis (RO) unit (304, 404) to the drain line (2A, 2B), the hydraulic system is still "rigid" under normal operation of the water purification unit (WPA).

[0160] FIG. 10b is a flowchart of an exemplary method (M8) for controlling the water purification device (WPA) in FIG. 10a. This method (M8) can be performed by the control device (500) in FIG. 1. In step S81, a target flow rate (TF1b) for the product water (PWA) generated by the water purification device (WPA) is obtained. In step S82, a target pressure (TP2) at the inlet of the second feed pump (403) is obtained. The target values ​​(TF1b, TP2) can be retrieved from memory (502 in FIG. 1) and / or input by an operator at the input interface of the water purification device (WPA), e.g., the HMI device (503) in FIG. 1. The method (M8) initiates two control routines that are performed independently of each other. In one routine, steps S83 and S84 are performed repeatedly. In step S83, a measured value of the flow rate of the product water (PWA) from the second system (400) is obtained from the measurement signal (F1). In step S84, a control signal (PC1 in FIG. 10a) for the first feed pump (302) is generated to match the measured value to the target value (TF1). Step S84 may be based on any suitable control algorithm including feedback control using P control, PI control, or PID control, or feedforward control. In other routines, steps S85 and S86 are performed repeatedly. In step S85, a measured value of the inlet pressure to the second feed pump (403) is obtained from the measurement signal (P2). In step S86, a control signal (PC3 in FIG. 10a) for the second feed pump (403) is generated to match the measured value to the target value (TP2). Step S86 may be based on any suitable control algorithm including feedback control using P control, PI control, or PID control, or feedforward control.

[0161] FIG. 11 is a block diagram of an exemplary water purification device (WPA) implementing an alternative to the seventh concept. Compared to the water purification device (WPA) of FIG. 10a, the water purification device (WPA) of FIG. 11 includes a flow meter (408') placed between the first system (300) and the second system (400) to measure the flow rate of treated water from the first system (300) to the second system (400). The first controller (511') is configured to generate a control signal (PC1) for the first feed pump (302) based on a signal (F2) from the flow meter (408') to achieve a target flow rate (TF2) of treated water into the second system (400). The second controller (512') is configured to generate a control signal (PC3) for the second feed pump (403) based on a signal (F1) from the flow meter (408) to achieve a target flow rate (TF1) of product water (PWA) from the second system (400).

[0162] The controllers (511', 512') in FIG. 11 can operate to control the water purification device (WPA) to generate a target flow rate (TF1) of product water (PWA), and such control is sensitive to disturbances. One reason for this is that the control is separated into two consecutive control routines: one control routine for the first system (300) and one control routine for the second system (400). Accordingly, disturbances in the first system (300) will directly affect the control of the second system (400). Compared to the seventh concept (Figs. 10a and 10b), the control in FIG. 11 is less stable. In the seventh concept, one control routine operates both systems (300, 400) jointly to generate product water (PWA) at a target flow rate, and another control routine ensures the proper operation of the second feed pump (403). This ensures the stable operation of both systems (300, 400) even if one of the systems (300, 400) experiences disturbance. Another disadvantage of the control in FIG. 11 is that the risk of cavitation in the second feed pump (403) is not resolved. This risk can increase over time as the contamination of the reverse osmosis (RO) membrane (304') increases, if the contamination reduces the inlet pressure of the second feed pump (403). Cavitation can potentially damage the second feed pump (403). In the seventh concept, the risk of cavitation is minimized.

[0163] FIG. 12 is a block diagram of a variation of the first concept in FIG. 4a. Compared to FIG. 4a, both reverse osmosis (RO) units (304, 404) are configured as sacrificial components. Thus, just like the first reverse osmosis (RO) unit (304), the second reverse osmosis (RO) unit (404) is also detachably installed by a releaseable connector (404A, 404B', 404C') (see 404A', 404B', 404C' in FIG. 2d) connected to the corresponding port of the second reverse osmosis (RO) unit (404). Using disposable reverse osmosis (RO) units in both systems (300, 400) can simplify the water purification device (WPA).

[0164] The applicant currently determines that the modification in FIG. 12 is particularly useful when there is a possibility that the use of the water purification unit (WPA) may be interrupted for a longer period, for example, several days, more than one week, or even more than one month. Such discontinuous operation may occur when the water purification unit (WPA) is used to generate product water (PWA) in intensive care. For example, product water (PWA) may be supplied to a mixing unit that generates therapeutic fluid for a dialysis machine used in intensive care to treat patients suffering from acute kidney injury (AKI) via dialysis therapy, e.g., PD or Continuous Renal Replacement Therapy (CRRT). Patients of this type are relatively not uncommon in intensive care units (ICUs). About 5% to 30% of patients in the ICU may require dialysis therapy. Between a specific use and the next, the water purification unit (WPA), the mixing unit, and the dialysis machine may be stored away. In some embodiments, two or more of the water purification device (WPA), mixing unit, and dialysis machine may be combined into a single machine.

[0165] The theoretical basis for equipping the water purification device (WPA) with only disposable reverse osmosis (RO) units (304, 404) is to improve patient safety and reduce the startup time of the water purification device (WPA) after storage. In some embodiments, the control device (500) is configured to command the user to replace both reverse osmosis (RO) units (304, 404). For example, such a command may be provided whenever the water purification device (WPA) is started after storage. In some embodiments, when the storage time exceeds a predetermined time limit, for example, when it exceeds 2 to 7 days, a replacement command is automatically provided by the control device (500). Additionally, it may be considered that a replacement command be provided whenever the total usage time or total installation time of the reverse osmosis (RO) unit (304, 404) exceeds a predefined limit, or that the reverse osmosis (RO) unit (304, 404) be operated to produce a predefined amount of product water.

[0166] In some embodiments, the target lifespan of the corresponding reverse osmosis (RO) units (304, 404) may be shorter than when only the first reverse osmosis (RO) unit (304) is disposable (Fig. 4). This can significantly reduce the cost of the reverse osmosis (RO) units (304, 404) and is made possible by considering the fact that the water purification device (WPA) is likely to be used only for a relatively short time between a specific storage and the next storage.

[0167] It should be understood that the water purification device (WPA) can be operated in the same manner as the method (M5) in FIG. 4b to replace the reverse osmosis (RO) units (304, 404). Accordingly, the user may be instructed to disconnect and remove the reverse osmosis (RO) units (304, 404) (step S51), and accordingly, the water purification device (WPA) may be operated to perform cleaning, sanitization, or disinfection of the hydraulic systems of the first system (300) and the second system (400) (step S53). Once this operation is completed, the user is instructed to install new reverse osmosis (RO) units (304, 404) in the water purification device (WPA). Accordingly, the water purification device (WPA) is prepared to be started, for example, according to the methods (M1 to M3) in FIG. 3a to 3c. The second system (400) will recognize that it can be primed by a method similar to the method (M1) for primed the first system (300).

[0168] In light of growing environmental issues, it is desirable to reduce power consumption by water purification devices (WPA). This objective can be achieved by the exemplary water purification device (WPA) in FIG. 13a, which illustrates a simplified aspect of the first system (300). The second system (400) is not illustrated in FIG. 13a but can be configured to correspond to FIG. 2c and is fluidly connected to the first system (300) at points D, E, and F. The pretreatment system (100) is optional and is indicated by dashed lines. The following description will focus on the added components compared to the water purification device (WPA) in FIG. 2a through 2c.

[0169] When the water purification unit (WPA) is operating to produce product water, the heater (313) is operated to heat the water passing through the heater to achieve a target temperature of the water entering the second system (400). The target temperature may be set to achieve a predefined temperature of the product water produced by the second system (400) or by the operating requirements of the second system (200). In some embodiments, the target temperature is within the range of 25°C to 37°C. While the water purification unit (WPA) is operating to produce product water, the water in the tank (200) will be at a high temperature as a result of the recirculation of fluid in the water purification unit (WPA). In the example of FIG. 13a, the high-temperature product water is returned to the first system (300) via the return line (5) and transported to the tank via the return line (8). Furthermore, high-temperature wastewater is returned from the reverse osmosis (RO) unit (404) to the tank (200) through the drain line (2B). Like the water in the tank (200), the wastewater in the drain line (2A) from the reverse osmosis (RO) unit (304) will exhibit a high temperature.

[0170] During the production of product water, the tank (200) will be replenished by receiving raw water (SWA) and optionally pretreated by the pretreatment system (100). The temperature of the raw water (SWA) is typically much lower than the target temperature. It is not uncommon for tap water to be in the range of 5°C to 15°C. This means that whenever the tank (200) is replenished, the water temperature in the tank (200) will decrease. Unless for replenishment, the heater (313) would only need to compensate for heat loss in the water purification device (WPA). However, replenishment with low-temperature raw water (SWA) significantly increases the power consumption of the heater (313).

[0171] In FIG. 13a, this problem is solved by the addition of a heat transfer device (HTD) (50) arranged to transfer energy (heat) (H1) from a first location ("locus") (HL1) in the drain line (2A) to a second location ("locus") in the main flow path (1) upstream of the heater (313). FIG. 13a illustrates two examples of the second location, namely a location upstream of the tank (200) (HL2) or a location downstream of the tank (200) (HL3). By the heat transfer device (HTD) (50), heat that would otherwise have escaped to the drain (309) is recovered, and this heat is used to heat the water upstream of the heater (313). This reduces the power consumption of the heater (313). It may be desirable for HL2 to be the second location for heat transfer because the temperature difference between HL1 and HL2 is greater than the temperature difference between HL1 and HL3, and a larger temperature difference implies better heat transfer efficiency. As mentioned above, the flow rate of raw water (SWA) into the tank (200) may vary over time and may even be intermittent. Under these conditions, since variable flow in HL2 can reduce heat transfer efficiency, it may be desirable for HL3 to be the second location for heat transfer. However, depending on the temperature and flow rate in the water purification device (WPA), the heat transfer capacity between HL1 and HL2 may be better even if the inflow of raw water (SWA) varies over time.

[0172] In some embodiments, as illustrated in FIG. 13a, a second location (HL2 / HL3) is located upstream of the reverse osmosis (RO) unit (304). This will increase the temperature of the water entering the reverse osmosis (RO) unit (304), thereby improving the filtration performance of the reverse osmosis (RO) unit (304). It is well known that this fluid temperature is a key factor in the performance of the reverse osmosis (RO) membrane (304' in FIG. 2d). Generally, permeate flow increases as the water temperature rises. However, the salt waste rate of the reverse osmosis (RO) unit (304) decreases as the water temperature rises. For a number of reverse osmosis (RO) units, the optimal temperature is in the range of 20°C to 30°C, typically 25°C or close to this. The water temperature may be increased by a heat transfer device (HTD) (50) to increase the flow rate of the permeate water. This means that the flow rate of wastewater is reduced, and as a result, the energy loss to the drain (309) is further reduced.

[0173] In some embodiments, as illustrated in FIG. 13a, a second location (HL2 / HL3) is upstream of one or more sensors within the main flow path (1). The sensors have a rated temperature range, and the sensors are calibrated for use. Thus, for the sensors upstream of the heater (313), the heat transfer device (HTD) (50) can allow the sensors to have a relatively narrow temperature range. This can reduce the cost of the sensors and / or improve the performance of the sensors. In the example of FIG. 13a, the sensor (311) is positioned upstream of the heater (313). As previously described with reference to FIG. 8a, a signal (C2) from the sensor (311) can be used during the startup of the water purification device (WPA) to determine when to open the main flow path (1) and close the return flow path (8). As previously noted, the sensor (311) can be configured to measure composition-related parameters. In some embodiments, the sensor (311) is a conductivity sensor. Since such a sensor is known to be highly temperature-dependent, it is advantageous to have a limited operating range in terms of water temperature. The composition sensor (311) may also be used to monitor the operation and performance of the reverse osmosis (RO) unit (304) during the production of product water. In some embodiments, the water purification device (WPA) includes two conductivity sensors, namely one sensor upstream of the reverse osmosis (RO) unit (304) and one sensor downstream of the reverse osmosis (RO) unit (304), to enable the calculation of the salt disposal rate as is known in the art. It may be advantageous for the heat transfer device (HTD) (50) to be located upstream of both of these conductivity sensors.

[0174] In some embodiments, the heat transfer device (HTD) (50) is a heat exchanger that is fluid-interposed in the main flow path (1) and the drain line (2A). As used herein, "fluid interposed" means that the heat exchanger is inserted into a fluid line through which a fluid flowing along the fluid line passes. A schematic diagram of the heat exchanger (50) is shown in FIG. 13b. The heat exchanger (50) forms at least one first fluid channel (50A) that is fluid-interposed in the drain line (2A), and at least one second fluid channel (50B) that is fluid-interposed in the main flow path (1). The heat exchanger is a passive device designed to transfer a nominal amount of heat (H1) from the fluid in the first fluid channel (50A) to the fluid in the second fluid channel (50B), or vice versa, for a given fluid and a given flow rate. As described above, the transfer of heat (H1) reduces the power consumption of the heater (313). The heat exchanger (50) can be of any type, such as a plate heat exchanger, a tube heat exchanger, or a spiral heat exchanger, and can be arranged in a counter flow configuration or a parallel flow configuration.

[0175] It may be desirable for the temperature of the water entering the reverse osmosis (RO) unit (304) and / or sensor (311) to be well controlled. To this end, the heat transfer device (HTD) (50) may be a heat pump operable to transfer thermal energy (heat) between HL1 and HL2 / HL3, or may include such a heat pump. The heat pump (50) is an active device electrically operable to control the amount of heat (H1) transferred. Additionally, the direction of transfer by the heat pump (50) may be controlled. The amount of heat (H1) is "controlled" in the sense that the amount of such heat is optionally adjustable.

[0176] The heat pump (50) can be controlled by a control device (500 in FIG. 1) to achieve a target temperature, for example, at a selected location between HL2 / HL3 and the heater (313). In FIG. 13a, the control device can use a signal (T2) from the temperature sensor (310) to cause the heat pump (50) to operate to achieve a controlled water temperature at the sensor (311). Alternatively, if the temperature sensor is located in the main flow path (1) upstream of the reverse osmosis (RO) unit (304), the heat pump (50) can be controlled to achieve a controlled water temperature at the inlet of the reverse osmosis (RO) unit (304).

[0177] In a modified example, the heat pump (50) and the heater (313) are jointly controlled to achieve a target temperature in the main flow path (1) downstream of the heater (313).

[0178] If the heat pump (50) has a sufficiently large heat transfer capacity, the heater (313) may be omitted.

[0179] Another technical advantage of using a heat pump (50) is the ability to reverse the direction of energy transfer. In the example of FIG. 13a, reversing the direction of energy transfer means that heat (H1) is transferred from HL2 / HL3 to HL1. By doing so, the temperature of the water entering the reverse osmosis (RO) unit (304) can be lowered by the heat pump (50). This reversal of direction extends the utility of the water purification device (WPA) by, for example, allowing a wider range of raw water (SWA) temperatures. For example, the direction of the heat pump (50) can be switched when the raw water (SWA) temperature exceeds a predetermined limit, said limit can be set considering the aforementioned optimal temperature of the reverse osmosis (RO) unit (304). The raw water (SWA) temperature can be given by the output signal (52) of a sensor (51) in the main flow path (1) upstream of the tank (200). Another reason for lowering the temperature of the water entering the reverse osmosis (RO) unit (304) may be to alleviate scaling in the first system (300). When the water purification device (WPA) is operated in an area with high water hardness, scaling of the reverse osmosis (RO) membrane may become critical, which may result in more frequent replacement of the reverse osmosis (RO) unit (304) or the use of scaling removal procedures. Scaling increases as the water temperature rises. Therefore, in an area with high water hardness, the heat pump (50) may be operated to lower the water temperature in the reverse osmosis (RO) unit (303) to a target temperature below the optimal temperature for the reverse osmosis (RO) unit. In some embodiments, this water hardness is inferred from the output signal (52) of a sensor (51), which may be an online water hardness meter, a conductivity sensor, etc.

[0180] In some embodiments, the heat pump (50) is a conventional heat pump that operates to transfer thermal energy by utilizing a cooling cycle. Such a heat pump is power efficient.

[0181] In some embodiments, the heat pump (50) is a thermoelectric heat pump, also known as a Peltier device or Peltier heat pump. Generally, a thermoelectric heat pump is a solid-state device that transfers heat from one side of the device to the other through the consumption of electrical energy along the direction of the current. Compared to conventional heat pumps, thermoelectric heat pumps have the advantages of being small, quiet, operating without moving parts, having a long operating life, and requiring little to no service and maintenance.

[0182] FIG. 13a is given merely as a non-limiting example. A heat transfer device (HTD) (50) may be provided in any water purification device (WPA) described herein, for example, according to the first to seventh concepts and any associated embodiments, variations, or examples.

[0183] In the specific context of FIG. 13a, a water purification device (WPA) can be defined as a device for generating water for medical products, and such a device,

[0184] A main flow path extending from a main water inlet to a main water outlet;

[0185] A first system configured to be positioned in a main flow path and to treat influent water to reduce water hardness, thereby obtaining treated water with reduced hardness, wherein the first system comprises a first reverse osmosis (RO) unit, a first feed pump for feeding influent water to the first reverse osmosis (RO) unit, and a drain line for guiding wastewater from the first reverse osmosis (RO) unit to a drain;

[0186] A second system positioned between a first system and a main water outlet in a main flow path, wherein the second system is configured to receive treated water from the first system and further treat the treated water into the product water;

[0187] A storage tank positioned in the main flow path upstream of the first system and configured to hold the inflow water for the first system;

[0188] A recirculation path extending from a first location within the main flow path downstream of the second system to a storage tank; and

[0189] A heat transfer device configured to transfer heat between a first locus in the drain line and a second locus in the main flow path upstream of the reverse osmosis (RO) unit.

[0190] Includes

[0191] In some embodiments, the second locus is upstream of the storage tank.

[0192] In some embodiments, the second locus is located between the storage tank and the reverse osmosis (RO) unit.

[0193] In some embodiments, the heat transfer device includes at least one of a heat exchanger or a heat pump.

[0194] In some embodiments, the water purification device (WPA) further includes a control device configured to operate a heat pump to achieve a target temperature of the influent water in a reverse osmosis (RO) unit.

[0195] In some embodiments, the control device is configured to operate a heat pump to transfer heat from a first locus to a second locus.

[0196] In some embodiments, the control device is configured to selectively reverse the heat pump to transfer heat from the second rocker to the first rocker.

[0197] In some embodiments, the control device is configured to selectively reverse the heat pump based on a signal indicating the temperature and / or hardness of the inflow water to the third system.

[0198] In some embodiments, the heat pump is a thermoelectric heat pump.

[0199] In some embodiments, an electric heater in the main flow path is further included, and the second rocker is upstream of the electric heater.

[0200] It will be understood that although the subject matter of this disclosure has been described in relation to what is considered to be the most practical and preferred embodiment at present, the subject matter of this disclosure should not be limited to the disclosed embodiment, but rather is intended to encompass various modifications and equivalent devices included within the spirit and scope of the appended claims.

[0201] Furthermore, although the operation of the device is illustrated in the drawings in a specific order, this should not be understood as requiring that the operation be performed in the specific order or sequential order illustrated to achieve a desired result, nor as requiring that all illustrated operations be performed. In certain situations, parallel processing may be advantageous.

Claims

Claim 1 As a device for generating medical product water, the device comprises a main flow path (1) extending from a main water inlet (1') to a main water outlet (1"), a first system (300) disposed in the main flow path (1) and configured to treat incoming water to reduce water hardness, thereby obtaining treated water with reduced water hardness, and a second system (400) disposed between the first system (300) and the main water outlet (1") in the main flow path (1), wherein the second system (400) is configured to receive treated water from the first system (300) and further treat this treated water into the product water, the first system (300) includes a reverse osmosis (RO) unit (304) for use in treating incoming water, and the main flow path (1) includes the reverse osmosis (RO) unit (304). The first system (300) includes a feed line (1A) extending to a water inlet (304A') on the feed side (304"), and the first system (300) includes a feed pump (302) disposed in the feed line (304) to pressurize the inflow water at the water inlet (304A') of the reverse osmosis (RO) unit (304), and the device for generating the water for medical products includes a return flow path (8) disposed to fluidly connect a main flow path (1) at a location between the first system (300) and the second system (400) to the feed side (304") of the reverse osmosis (RO) unit (304), and a valve device (314, 401) operable to selectively guide treated water from the first system (300) to the second system (400) on the main flow path (1) or to the feed side (304") of the reverse osmosis (RO) unit (304) on the return flow path (8). The device for generating the above-mentioned water for medical products is configured to perform a start-up procedure, and in the start-up procedure, the valve device (314, 401) is,A device for generating water for medical products, wherein the main flow path (1) is operated to close and the return flow path (8) is opened, the feed pump (302) is started and operated for a specific time interval, and the valve device (314, 401) is operated to open the main flow path (1) and optionally close the return flow path (8) after the time interval. Claim 2 A device for generating water for medical products according to claim 1, wherein the return flow path (8) extends to a position on the main flow path (1) upstream of the feed pump (302). Claim 3 An apparatus for generating medical product water according to claim 1 or 2, further comprising a sensor (311) disposed between the first system (300) and the valve device (314, 401) in the main flow path (1), wherein the sensor (311) is configured to generate a sensor signal (C2) representing parameters related to the composition of the treated water, and wherein the apparatus for generating medical product water is configured to determine the time interval based on the sensor signal (C2). Claim 4 A device for generating water for medical products, wherein, in paragraph 3, the composition-related parameter corresponds to electrical conductivity. Claim 5 An apparatus for generating water for medical products, wherein, in any one of claims 1 to 4, the first system (300) further comprises a drain line (2A) extending from a retentate outlet (304C') on the feed side (304") of a reverse osmosis (RO) unit (304), and a flow limiting device (306) is disposed in the drain line (2A) to form a flow resistance at the retentate outlet (304C') on the feed side (304") of the reverse osmosis (RO) unit (304). Claim 6 In paragraph 5, the above flow limiting device (306) is operable to change the flow resistance based on a control signal, a device for generating water for medical products. Claim 7 An apparatus for generating water for medical products, wherein, in claim 5 or 6, the first system (300) comprises a connection line (3A) arranged to be in fluid communication with a drain line (2A) and a feed line (1A) to form a recirculation path from a residual outlet (304C') on the feed side (304") of a reverse osmosis (RO) unit (304) to a water inlet (304A') on the feed side (304") of a reverse osmosis (RO) unit (304), and an auxiliary pump (305) arranged in the recirculation path to provide an additional flow rate along a second flow path (FP2). Claim 8 In claim 7, the device for generating water for medical products, wherein the auxiliary pump (305) is placed in the connection line (3A). Claim 9 In claim 7 or 8, the reverse osmosis (RO) unit (304) forms a permeable side (304) separated from the feed side (304) by a semipermeable membrane (304'), the reverse osmosis (RO) unit (304) includes a water inlet (304A') on the feed side (304) and a permeable outlet (304B') on the permeable side (304), the main flow path (1) includes a first flow path (FP1) from the water inlet (304A') to the permeable outlet (304B') through the semipermeable membrane (304'), and the reverse osmosis (RO) unit (304) further includes a residual outlet (304') on the feed side (304) so ​​that residual from the water inlet (304A') along the semipermeable membrane (304') A device for generating water for medical products, which forms a second flow path (FP2) on the feed side (304) to the outlet (304C'). Claim 10 An apparatus for generating water for medical products, comprising, in any one of claims 1 to 9, a storage tank (200) positioned in the main flow path (1) upstream of the first system (300) and configured to maintain the inflow water for the first system (300) at atmospheric pressure. Claim 11 A device for generating water for medical products according to claim 10, wherein the storage tank (200) comprises a water inlet port (202) connected for fluid communication with a main water inlet (1'), and the storage tank (200) is configured to form an air gap (207) above a predetermined upper level of the inflow water inside the storage tank (200). Claim 12 In claim 11, the above storage tank (200) comprises a level sensor (201) for signaling at least one fluid level in the storage tank (200) so that the control device (500) can control the inflow of water through the water inlet port (202) to maintain an air gap (207) in the storage tank (200), for a device for generating water for medical products. Claim 13 An apparatus for generating water for medical products, wherein, in any one of claims 10 to 12, it further comprises a vent (206) in the side wall of a storage tank (200), said vent (206) is configured to release both gas and water from the storage tank (200). Claim 14 A device for generating water for medical products, wherein, in any one of claims 10 to 13, the return flow path (8) extends to a return port (204) on a storage tank (200). Claim 15 An apparatus for generating medical product water, wherein, in any one of claims 1 to 14, it further comprises a recirculation path (5, 6) extending from a first location in a main flow path (1) downstream of the second system (400) to a second location in a main flow path (1) upstream of the first system (300) and / or a third location between the first system (300) and the second system (400) in the main flow path (1) to provide recirculation of product water generated by the second system (400). Claim 16 In any one of claims 1 to 4 or claims 10 to 15, the first system (300) comprises a drain line (2A) for guiding reject water from a reverse osmosis (RO) unit (304) to a drain (309), and the device for generating water for medical products further comprises a heat transfer device (50), wherein the heat transfer device (50) is configured to transfer heat between a first locus (HL1) in the drain line (2A) and a second locus (HL2; HL3) in the main flow path (1) upstream of the reverse osmosis (RO) unit (304). Claim 17 In claim 16, the above heat transfer device (50) comprises at least one of a heat exchanger and a heat pump, a device for generating water for medical products. Claim 18 A device for generating water for medical products according to claim 17, further comprising a control device (500) configured to operate a heat pump to achieve a target temperature of the influent water in the reverse osmosis (RO) unit (304). Claim 19 In claim 18, the control device (500) is configured to operate a heat pump (50) to transfer heat from a first locus (HL1) to a second locus (HL2; HL3), for a device for generating water for medical products. Claim 20 In claim 19, the control device (500) is configured to selectively reverse the heat pump (50) to transfer heat from the second locus (HL2; HL3) to the first locus (HL1), for a device for generating water for medical products. Claim 21 In claim 20, the control device (500) is configured to selectively reverse the heat pump (50) based on a signal (52) indicating the temperature and / or hardness of the water flowing into the first system (300), for a device for generating water for medical products. Claim 22 A device for generating water for medical products, wherein in any one of claims 18 to 21 in combination with claim 3 or 4, the second locus (HL2; HL3) is located upstream of a sensor (311) configured to generate a sensor signal (C2) representing a composition-related parameter. Claim 23 In paragraph 22, the control device (500) is configured to operate a heat pump to achieve the target temperature of the treated water at a sensor (311) configured to generate a sensor signal (C2) representing a composition-related parameter, for the production of water for medical products. Claim 24 An apparatus for generating water for medical products, wherein, in any one of claims 17 to 23, the heat pump is a thermoelectric heat pump. Claim 25 A device for generating water for medical products, wherein, in any one of claims 1 to 24, the reverse osmosis (RO) unit (304) is a sacrificial component that is detachably installed in the first system (300). Claim 26 In claim 25, the reverse osmosis (RO) unit (304) has a target lifespan capable of producing 20,000 L to 100,000 L of the treated water, preferably 40,000 L to 70,000 L of the treated water, for a device for producing water for medical products. Claim 27 An apparatus for producing water for medical products, wherein, in paragraph 25 or 26, the target life is defined for the inflow water to the reverse osmosis (RO) unit (304) having a hardness of 450 ppm and / or a conductivity of 2000 μS / cm, and for the treated water produced at a flow rate of 1 L / min. Claim 28 A device for generating medical product water according to any one of claims 25 to 27, configured to generate product water at a point of care, wherein the device for generating medical product water is configured to provide replacement of a first reverse osmosis (RO) unit (304) by an untrained user at the point of care. Claim 29 An apparatus for generating water for medical products according to any one of claims 1 to 28, further comprising a monitoring device (500') configured to determine a performance parameter representing flow resistance through a reverse osmosis (RO) unit (304) based on an output signal of a sensor (302, 320, 321) within the apparatus for generating water for medical products, and to evaluate said performance parameter to detect the need for replacement of the reverse osmosis (RO) unit (304). Claim 30 An apparatus for generating water for medical products according to claim 29, wherein the sensors (302, 320, 321) comprise at least one of a pressure sensor (303) in the main flow path (1) upstream of a reverse osmosis (RO) unit (304), a flow meter (320) in the main flow path (1) downstream of a reverse osmosis (RO) unit (304), and a power sensor (321) for measuring the power consumption of a feed pump (302). Claim 31 An apparatus for generating water for medical products, wherein, in any one of claims 1 to 30, the second system (400) comprises a second reverse osmosis (RO) unit (404) for use in treating water from the first system (300). Claim 32 In paragraph 31, the second reverse osmosis (RO) unit (404) is a device for generating water for medical products that is permanently installed in the second system (400). Claim 33 A device for generating water for medical products according to claim 31 or 32, wherein the residual outlet (404C') of the second reverse osmosis (RO) unit (404) is connected for fluid communication with the main flow path (1) at an upstream location of the first system (300) to provide recirculation of residual water from the second reverse osmosis (RO) unit (404) into the main flow path (1). Claim 34 An apparatus for generating water for medical products, wherein, in any one of claims 1 to 33, it further comprises a pretreatment system (100), wherein the pretreatment system (100) is positioned in a main flow path (1), receives raw water from a main water inlet (1'), and is configured to provide pretreatment water by removing particles from at least said raw water, and the first system (300) is fluidly connected to receive pretreatment water from the pretreatment system (100). Claim 35 In paragraph 34, the above pretreatment system (100) is also configured to remove chlorine from the raw water, a device for generating water for medical products. Claim 36 An apparatus for producing water for medical products, wherein, in any one of claims 1 to 35, it further comprises at least one radiation source (301) disposed in the main flow path (1) upstream of the reverse osmosis (RO) unit (304), and said radiation source (301) is operable to emit UV radiation to remove chlorine in the influent water to the reverse osmosis (RO) unit (304). Claim 37 A computer implementation method for operating a device for generating medical product water, wherein the device for generating medical product water comprises: a main flow path (1) extending from a main water inlet (1') to a main water outlet (1"); a first system (300) disposed in the main flow path (1) and configured to process incoming water to reduce water hardness and consequently obtain processed water with reduced hardness; and a second system (400) disposed between the first system (300) and the main water outlet (1") in the main flow path (1), wherein the second system (400) is configured to receive processed water from the first system (300) and further process this processed water into the product water, and the first system (300) comprises a reverse osmosis (RO) unit (304) for use in treating incoming water, and the device for generating medical product water comprises a return flow path (8) and a valve device (314, 401), and the return flow path (8) comprises A main flow path (1) at a location between the first system (300) and the second system (300, 400) is arranged to fluidly connect to the feed side (304") of the reverse osmosis (RO) unit (304), and the valve device (314, 401) is operable to selectively guide the treated water from the first system (300) to the second system (400) on the main flow path (1) or to the feed side (304") of the reverse osmosis (RO) unit (304) on the return flow path (8), and the main flow path (1) includes a feed line (1A) extending to a water inlet (304A') on the feed side (304") of the reverse osmosis (RO) unit (304), and the first system (300) is in the feed line (1A) to pressurize the inflow water at the water inlet (304A') of the reverse osmosis (RO) unit (304). The computer-implemented method includes a deployed feed pump (302), and comprises the steps of: operating the valve device to close the main flow path and open the return flow path (S61); starting the feed pump and operating the feed pump for a specific time interval (S62);A computer-implemented method for operating a device for generating water for medical products, comprising the step (S65) of operating a valve device to open a main flow path after the above time interval. Claim 38 A computer-readable medium comprising program instructions that, when executed by a processor (501), cause the processor (501) to perform a computer implementation method for operating a device for generating water for medical products according to claim 37.

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