Disinfection of systems for generating treatment fluid for use in dialysis

Abstract

A system is configured to provide treatment fluid for use in dialysis therapy. A first sub-system (30) provides a flow of product water in a circulation path (34). A second sub-system (10) is fluidly connected to the circulation path on first and second connecting paths (CP1, CP2) and is operable to generate treatment fluid by use of product water. In a disinfection mode of the system, the second sub-system obtains product water on the first or second connecting path, produces a disinfection fluid based on the product water, and performs a disinfection of at least part of the second sub-system by use of the disinfection fluid. As part of the disinfection mode, the second sub-system generates a throughflow of disinfection fluid in the first and second connecting paths and in the circulation path between the first and second connecting paths, allowing the second sub-system to be disinfected separately from the first sub-system.

Description

[0001] DISINFECTION OF SYSTEMS FOR GENERATING TREATMENT FLUID FOR USE IN DIALYSIS

[0002] Technical Field

[0003] The present disclosure relates generally to dialysis, and in particular to systems for generating treatment fluid for use in dialysis and techniques for disinfecting such systems.

[0004] Background Art

[0005] Dialysis therapy is a therapy that replaces the normal blood-filtering function of the kidneys. It is used when the kidneys are not working well, which is known as kidney failure and includes acute kidney injury (AKI) and chronic kidney disease (CKD). Dialysis involves removal of water from the blood of the patient suffering from kidney failure, as well as exchange of solutes with the blood. One example of dialysis therapy is peritoneal dialysis (PD), in which a treatment fluid is infused into the peritoneal cavity of the patient to interface with the blood of the patient through the peritoneal membrane. Another example of dialysis therapy is extracorporeal (EC) blood therapy, in which blood is circulated outside of the patient and interfaced with one or more treatment fluids. Modalities of extracorporeal blood therapy include hemodialysis (HD), hemofiltration (HF) and hemodiafiltration (HDF).

[0006] Treatment fluids used in PD and HD are commonly known as dialysis fluids. In HF, the treatment fluid is known as replacement fluid, since it is infused into the blood of the patient to replace fluid removed during therapy. In HDF, both dialysis fluid and replacement fluid are used.

[0007] Dialysis therapy is typically automated and performed under control of a dialysis machine. In PD, the machine is known as a cycler, which is connected in fluid communication with the peritoneal cavity and is operated to control the flow of fresh dialysis fluid into the peritoneal cavity and the flow of spent dialysis fluid from the peritoneal cavity. In EC blood therapy, there are two main categories of machines: "chronic machines" for treatment of patient suffering from CKD, and "acute machines" for treatment of patients suffering from AKI.

[0008] Over time, dialysis therapy consumes large quantities of medical fluid. In some modalities of dialysis therapy, pre-made medical fluid is delivered in prefilled bags to the point of care. For example, conventional automated PD is performed by use of prefilled bags. AKI machines are configured to use prefilled bags of medical fluid, by staff installing a prefilled bag before treatment, and replacing the prefilled bag as required. On the other hand, CKD machines have integrated capability to generate treatment fluid by mixing one or more concentrates with purified water of well-defined quality. Recently, PD machines with integrated capability of fluid generation have been proposed.

[0009] There is a general desire to advance generation of treatment fluid for all types of dialysis therapy. Another desire is to enable generation of treatment fluid even if purified water is not available.

[0010] It is also desirable for the generation of treatment fluid to be made in a system made up of re-usable or permanent components to the largest extent possible. This will both minimize the environmental impact, by reducing the amount of components that go to waste, as well as reduce the need for manual intervention by the user to prepare the system for fluid generation. The provision of re-usable or permanent components in a system for generation of treatment fluid results in a need to implement a technique of disinfecting the system.

[0011] Summary

[0012] It is an objective to at least partly overcome one or more limitations of the prior art.

[0013] One objective is to provide a system for generating treatment fluid for use in dialysis from source water with insufficient quality for use in dialysis.

[0014] Another objective is to provide a technique of disinfecting such a system.

[0015] Yet another objective is to provide such a technique that provides improved control of the microbial status of the system.

[0016] One or more of these objectives, as well as further objectives that may appear from the description below, are at least partly achieved by a system for providing a treatment fluid, a computer-implemented method, and a computer-readable medium according to the independent claims, embodiments thereof being defined by the dependent claims.

[0017] The present disclosure proposes a technique for fluid generation that may be implemented in a dialysis machine or in a stand-alone machine for fluid generation. The technique may be used for generating treatment fluid on-demand for use in on-going dialysis therapy, or for generating treatment fluid for intermediate storage in advance of dialysis therapy. The proposed technique involves a system that includes a first subsystem for processing supply water into product water for use in dialysis, and a second sub- system for generating treatment fluid from product water provided by the first subsystem. The product water is purified water, which is generated by the supply water being processed by a water purification arrangement in the first sub-system. The first sub-system is thus configured to subject the supply water to purification processing for generation of the product water. The system is versatile in that it is operable to generate treatment fluid from supply water that does not fulfil quality requirements for dialysis therapy. The consumption rate of product water by the second sub-system is rendered independent of the production rate of the product water by the first sub-system since the second sub- system is arranged to obtain the product water from a circulation path for product water in the first sub-system. This may be seen as the second sub-system tapping product water from the circulation path of the first sub-system as needed to generate the treatment fluid, as well as to generate a disinfection fluid for use in disinfection of the second sub-system. The disinfection fluid may be produced from the product water in any conventional manner, for example by heating of the product water and / or by adding a cleaning agent to the product water. By arranging two connecting paths between the second sub-system and the circulation path, is it possible to separately disinfect the second sub-system all the way to the connections of the connecting paths to the circulation path. The disinfection of the connecting paths may be performed efficiently by establishing a flow of the disinfection fluid from one connecting path via the circulation path to the other connecting path. The separation of the disinfection of the second sub-system from the disinfection of the first sub-system provides improved control over the full system in terms of its microbial status.

[0018] Still other objectives, aspects, embodiments and technical effects, as well as features and advantages may appear from the following detailed description, from the attached claims as well as from the drawings.

[0019] Brief Description of the Drawings

[0020] FIG. 1 is a block diagram of an example dialysis system configured for generation of PD fluid.

[0021] FIG. 2A is a block diagram of an example dialysis system comprising a water preparation sub-system, a fluid preparation sub-system, and a therapy sub-system, and FIG. 2B is a block diagram of an example water preparation system.

[0022] FIGS 3A-3B are flow charts of example methods for disinfection of a system for generation of treatment fluid.

[0023] FIG. 4 shows the system of FIG. 2A in different operating states while the system is in disinfection mode.

[0024] FIG. 5 shows the system of FIG. 2A when operated to release gas from the system.

[0025] FIG. 6 shows the system of FIG. 2A when operated to accommodate thermal expansion during heat disinfection. FIG. 7 is a block diagram of an example system for generation of treatment fluid.

[0026] FIGS 8A-8B are block diagrams of a system for generation of treatment fluid in accordance with a detailed example, and FIGS 8C-8D are schematic views of valve types used in the system of FIGS 8A-8B.

[0027] FIGS 9A-9B depict the system of FIGS 8A-8B in a production mode for generation of treatment fluid.

[0028] FIGS 10A-10G depict the system of FIGS 8A-8B in a disinfection mode, and FIGS 10H-10I depict an alternative system in a disinfection mode.

[0029] FIGS 11A-1 IB depict the system of FIGS 8A-8B when operated to release gas from the system, and FIG. 11C is a side view of an example filtration unit in the system of FIGS 8A-8B.

[0030] FIGS 12A-12B are section views of an example port in a connected state and a disconnected state, respectively.

[0031] FIG. 13 is a block diagram of an example control arrangement.

[0032] Detailed Description of Example Embodiments

[0033] Embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments are shown. Indeed, the subject of the present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure may satisfy applicable legal requirements.

[0034] Also, it will be understood that, where possible, any of the advantages, features, functions, devices, and / or operational aspects of any of the embodiments described and / or contemplated herein may be included in any of the other embodiments described and / or contemplated herein, and / or vice versa. In addition, where possible, any terms expressed in the singular form herein are meant to also include the plural form and / or vice versa, unless explicitly stated otherwise. As used herein, "at least one" shall mean "one or more" and these phrases are intended to be interchangeable. Accordingly, the terms "a" and / or "an" shall mean "at least one" or "one or more", even though the phrase "one or more" or "at least one" is also used herein. As used herein, except where the context requires otherwise owing to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, that is, to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments. As used herein, the terms "multiple", "plural" and "plurality" are intended to imply provision of two or more elements. The term "and / or" includes any and all combinations of one or more of the associated listed elements.

[0035] It will furthermore be understood that although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing the scope of the present disclosure.

[0036] Like reference signs refer to like elements throughout.

[0037] Well-known functions or constructions may not be described in detail for brevity and / or clarity. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0038] As used herein, "dialysis therapy" or "dialysis" refers to any therapy that replaces or supplements the renal function of a patient by use of a treatment fluid. Dialysis therapy includes, without limitation, extracorporeal (EC) blood therapy and peritoneal dialysis (PD) therapy.

[0039] As used herein, "treatment fluid" refers to any fluid that is consumed as a result of dialysis therapy. Treatment fluid includes, without limitation, dialysis fluid for infusion into the peritoneal cavity during PD therapy, dialysis fluid for supply to a dialyzer during EC blood therapy, and replacement fluid and substitution fluid for infusion into blood during EC blood therapy.

[0040] As used herein, "heat disinfection" refers to a technique of deactivating bacteria and viruses by subjecting them to a fluid at a required temperature for a required time period. The fluid may be water, optionally in combination with a cleaning agent ("disinfectant").

[0041] As used herein, "AO concept" refers to an established technique of quantifying the effect of heat disinfection on deactivation of microorganisms. An AO value may be calculated according to: AO T is the fluid temperature (in °C), z is a bacteria coefficient, and At is the exposure time at the fluid temperature. By use of this equation, a value of the microbial deactivation may be calculated, by summation or integration, during heat-up, holding, and cooling of any moist heat disinfection process. For example, a condition for sufficient heat disinfection may be that the AO value is at least 500, 600, 700, 800 or 900. Generally, the fluid temperature needs to exceed 65°C to be effective.

[0042] The present disclosure relates to a technique of ensuring the microbial integrity over time in a system for generating treatment fluid. The technique is applicable to systems for generation of treatment fluid for either peritoneal dialysis (PD) therapy or extracorporeal (EC) blood therapy. While the technique is mainly described and exemplified herein with reference to PD therapy, the skilled person has no difficulty of applying the technique to other forms of dialysis therapy.

[0043] FIG. 1 is a generic overview of a dialysis system 1 for PD therapy. The dialysis system 1 is fluidly connected to the peritoneal cavity PC of a patient P. As indicated by a double-ended arrow, the dialysis system 1 is operable to convey fresh dialysis fluid into PC and to receive spent dialysis fluid from PC on a fluid path 2. The fluid path 2 may be defined by tubing that connects to an implanted catheter (not shown) in fluid communication with the peritoneal cavity PC. A drain line 3 is connected to the dialysis system 1 for conveying the spent dialysis fluid to a drain 4, for example a floor drain, a toilet, a sink, a bag, or a container. PD therapy is typically implemented as daily treatment sessions, each comprising a number of fluid exchange cycles. The respective fluid exchange cycle may include a fill phase, a dwell phase and a drain phase, performed in sequence. In the fill phase, fresh dialysis fluid is supplied to PC on fluid path 2. In the dwell phase, the dialysis fluid resides in PC. In the drain phase, spent dialysis fluid is extracted from PC on fluid path 2.

[0044] In the illustrated example, the dialysis system 1 includes a therapy sub-system 20, which is operable to control the flows of fresh and spent treatment fluid, a fluid preparation sub-system 10 ("FPS"), which is operable to generate the treatment fluid for the therapy system 20 by mixing product water with one or more liquid concentrates, and a water purification system 30 ("WPS"), which is operable to generate the product water by purification processing of source water, for example tap water. Source water is also denoted "supply water" herein. The product water (PW) is purified water that may be produced to meet criteria of so-called "water for dialysis" "water for injection", or "ultrapure water". The FPS 10, the therapy system 20, and the WPS 30 may be implemented as a single machine or as two or more separate machines. The source water is received by the WPS 30 from a source 5 on a water supply line 6.

[0045] The liquid concentrate is a consumable that is supplied from a container or bag ("concentrate container"), which is connected for fluid communication with the FPS 10. In the example of FIG. 1, a liquid concentrate Cx is held in a concentrate container 7, which is removably connected to the FPS 10 of the dialysis system 1. The container 7 is thus a disposable unit that is regularly disconnected and replaced for a new container full of concentrate Cx. For example, the container 7 may be replaced when the remaining amount of concentrate Cx is deemed insufficient, or when a predefined time has elapsed since the container 7 was installed for use by the FPS 10. The container 7 may be attached directly to the FPS 10 or via a disposable tubing 8, as shown. FIG. 2A is a more detailed block diagram of an example dialysis system 1, comprising an FPS 10, a therapy sub-system 20, and an WPS 30.

[0046] The FPS 10 comprises a mixing arrangement 10', which is operable to mix PW with concentrate(s) to generate treatment fluid, TF. The mixing arrangement 10' may comprise a mixing chamber, an in-line mixer, an injector mixer, or any other conventional device for mixing liquids. The mixing arrangement 10' may be configured to generate TF in batches or on the fly. Here, "on the fly" (or "online") implies that TF is generated by continuously mixing the concentrate(s) into PW as PW flows through the mixing arrangement 10'. As shown, the mixing arrangement 10' includes at least one heater 9. The heater 9 may be an electrical heater or any other type of device capable of heating a passing fluid. The heater 9 may be used to heat TF to a target temperature suitable for dialysis therapy. The heater 9 may also be used in heat disinfection of the FPS. The mixing arrangement 10' includes a supply arrangement 11 for feeding concentrate(s) into the mixing arrangement 10'. The supply arrangement 11 is fluidly connected to a concentrate port P2. A terminal connector 8a on a tubing 8 that extends from a concentrate container 7 is releasably connected to the port P2 to direct the concentrate to the FPS. In an alternative, the tubing 8 is omitted, and a connector on the container 7 is directly attached to the port P2.

[0047] Although a single container 7 is shown in FIGS 1-2, the treatment fluid may be generated by mixing PW with any number of concentrates. Each such concentrate may be supplied from a respective container, which is releasably connected to a respective concentrate port on the FPS. As used herein, all ports on the FPS for inlet of concentrate are collectively denoted "input port arrangement".

[0048] In FIG. 2A, the FPS 10 comprises a plurality of additional ports Pl, P3, P4. The port Pl is a supply port ("outlet port") for TF and is arranged to receive TF from the mixing arrangement 10' on a fluid line LI. A terminal connector 21a on a disposable tubing 21 is releasably connected to the supply port Pl to direct TF to the therapy subsystem 20. The port P3 is a drain port, which is arranged to output discarded fluid from the mixing arrangement 10'. A drain line L3 extends from the mixing arrangement 10' to the port P3. A tubing 3 is connected by a terminal connector 3a to the port P3 and extends to the drain 4. The port P4 is a return port for spent treatment fluid from the therapy sub-system 20. A terminal connector 22a on a disposable tubing 22 is releasably connected to the port P4 to provide the spent treatment fluid from the therapy subsystem 20 to the FPS. A fluid line L4 extends from the port P4 to the mixing arrangement 10', which may be arranged to direct the spent treatment fluid via the drain line L3 to the drain port P3 for transport to the drain 4. The therapy sub-system 20 may be configured to perform PD therapy or EC blood therapy by use of TF from the FPS 10. The therapy sub-system 20 may be configured to accumulate a supply of TF for use during on-going or up-coming dialysis therapy, or use the TF as it is produced by the FPS ("on-demand"). Techniques and machines for performing PD therapy and EC blood therapy are well-known in the art and will not be further described.

[0049] The WPS 30 comprises a water purification arrangement 31, which is operable to generate product water (PW) from source water (SW). The purification arrangement 31 may include any conventional equipment for water purification. Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids, and gases from the water. The purification arrangement 31 may be configured to operate by membrane filtration or ion exchange, or a combination thereof. One commonly used membrane filtration technique for water purification is reverse osmosis (RO), in which an RO membrane is used to separate ions, molecules and larger particles from water. Ion exchangers (IEX) are also commonly used for water purification. Simply put, an ion exchanger operates to remove ionic impurities from water by replacing the respective ionic impurity by another ionic substance. Typical ion exchangers are ion-exchange resins (functionalized porous or gel polymer), zeolites, montmorillonite, clay, or soil humus. Electrodeionization (EDI) is also used for water purification. In principle any conventional or future water purification technique may be implemented in the purification arrangement 31.

[0050] In the WPS 30, a feed line 32 extends from the purification arrangement 31 to a water port 32a. A tubing 6 extends from a SW source (not shown) and has terminal connector 6a, which is connected to the port 32a. The WPS 30 further defines a circulation path 34. The purification arrangement 31 is connected and operable to circulate PW through the circulation path 34. A drain line 35 extends from the purification arrangement 31 to a drain port 35a on the WPS 30, and a terminal connector 33a on a disposable tubing 33 is connected to the drain port 35a. The disposable tubing 33 is arranged to extend to a drain 4.

[0051] The purification arrangement 31 also comprises at least one heater 36, which is operable to heat SW and / or PW. The heater 36 may be an electrical heater or any other type of device capable of heating a passing fluid. The heater 36 may be used to heat PW to a target temperature suitable for the FPS 10. The heater 36 may also be used in heat disinfection of the WPS 30. The purification arrangement 31 further includes a tank 37, which is fluidly connected to the circulation path 34 while PW is circulated therein. The tank 37 may contain an intermediate supply of PW. In an alternative, the tank 37 may be connected to receive SW from the feed line 32, as well as a mixture of SW and PW, and this combination is supplied from the tank 37 for purification processing. In some embodiments, the tank 37 is vented to the surroundings and fluid (PW, or a combination of PW and SW) is thus held in the tank 37 at atmospheric pressure. One use of the tank 37 will be explained below with reference to FIG. 6. The detailed structure of the WPS 30 is not relevant to the present disclosure and will not be described in further detail.

[0052] As seen in FIG. 2A, the FPS 10 is fluidly connected to the WPS 30 on two connecting paths CPI, CP2, which extend to a respective connection point Cl, C2 on the circulation path 34. Either of the connecting paths CPI, CP2 may be used for transferring PW from the WPS 30 to the FPS 10. It is also conceivable that different connecting paths CPI, CP2 are used for the transfer of PW at different stages during operation of the FPS 10. As will be described further below, the provision of two connecting paths CPI, CP2 enables simple and complete disinfection of the FPS 10.

[0053] In FIG. 2A, the system 1 is shown during production of treatment fluid TF, where thicker lines indicate passage of fluid and solid arrows indicate the flow direction. Source water SW is received by the WPS 30 and processed into product water PW, which is circulated on the circulation path 34. The FPS 10 retrieves PW on the connecting path CPI and concentrate from the container 7 via the port P2. The mixing arrangement 10' is operated to mix PW and concentrate, resulting in treatment fluid TF, which is supplied on fluid line LI to port Pl for receipt by the therapy sub-system 20.

[0054] In some embodiments, the FPS and the WPS are included in separate machines. In such embodiments, it may be desirable for the FPS and WPS to be releasably connected to each other, and each of the connecting paths CPI, CP2 may include a connecting line that is releasably connected to a PW outlet port (not shown) of the WPS and a PW inlet port (not shown) on the FPS. In other embodiments, the FPS and the WPS are integrated in a single machine and the connecting paths CPI, CP2 may establish a permanent connection between the WPS and the FPS.

[0055] FIG. 2B shows an example WPS 30. FIG. 2B is provided to give an overall understanding of how a WPS 30 may be configured to provide PW on a circulation path. Many alternatives are readily apparent to the skilled person. In FIG. 2B, the feed line 32 extends to the tank 37. An on / off valve 32' is arranged in the feed line 32 to control the admission of source water into the tank 37. As noted above, the tank 37 may be vented so that atmospheric pressure prevails in the tank 37. A main line 38 extends from a bottom portion of the tank 37 to the inlet of a purification device 31', which is configured to process the incoming water for purification, for example by membrane filtration and / or ion exchange. The drain line 35 is connected to the purification device 31' to receive drain fluid generated as a result of the purification. The circulation path 34 extends from the outlet of the purification device 31' to a top portion of the tank 37. Thus, the circulation path 34 directs processed ("purified") water from the purification device 3T back to the tank 37. A fluid pump 36a is arranged to pump water from the tank 37 to and through the purification device 3T, and to pump the purified water from the purification device 3T via the circulation path 34 back to the tank 37. Thereby, the WPS 30 is operable to continuously supply purified water on the circulation path 34. The purified water is equal to the above-mentioned product water, PW. Like in FIG. 2A, the FPS 10 is fluidly connected to the WPS 30 on two connecting paths CPI, CP2, which extend to a respective connection point Cl, C2 on the circulation path 34.

[0056] In the illustrated example of FIG. 2B, the heater 36 is arranged in the main line 38 between the pump 36a and the purification device 31'. In a variant, the heater 36 and / or the pump 36a may be part of the purification device 31'.

[0057] In the example of FIG. 2B, the WPS 30 includes at least one valve 39, 39' in the circulation path 34. The valve 39, 39' may serve one or more functions.

[0058] A first function may be to adjust the fluid pressure in the FPS 10. To this end, the valve 39, 39' is a variable restrictor, which is dynamically adjusted to maintain a target fluid pressure at a predefined location in the FPS 10. The variable restrictor may be adjusted to achieve a consistent pressure at a respective location ("dosing point") where a concentrate is dosed into the PW that is drawn into the FPS 10 from the WPS 30. A consistent pressure at the dosing point in the WPS 30 which will improve the ability of the FPS 10 to generate TF with a consistent and accurate composition. Alternatively or additionally, the variable restrictor may be adjusted, during heat disinfection of the FPS 10 (below), to achieve an elevated fluid pressure in the heater 9, which is active during the heat disinfection, so as to counteract boiling within the heater 9. This will improve the operational stability of the FPS 10 when it is operated for heat disinfection.

[0059] A second function may be to selectively close the circulation path 34 during part of the heat disinfection of the FPS 10, as will be describe below with reference to FIG. 4. The valve 39, 39' may be an on / off valve or a variable restrictor that is capable of being closed.

[0060] Each of the WPS and the FPS include durable fluid paths. As used herein, "durable" implies that the fluid paths are permanently installed. A durable fluid path needs to be intermittently disinfected to counteract microbial growth. The present disclosure is focused on disinfection of the FPS, although disinfection of the WPS will also be briefly discussed. In the following description, it is assumed that the disinfection of the FPS is performed by heat disinfection, in which PW is heated to a target temperature and conveyed through all fluid paths to be disinfected within the FPS. Here, the heated PW acts as a disinfection fluid. However, the disclosure is not limited to such a disinfection fluid. An alternative disinfection fluid comprises a cleaning agent ("disinfectant") and may or may not be heated. Non-limiting examples of disinfectants that are used for disinfection of dialysis systems include acetic acid, citric acid, peracetic acid, sodium hypochlorite, and sodium metabisulfite. The skilled person is equipped to adapt the techniques described herein to any type of disinfection fluid.

[0061] Thus, the FPS may be seen to include an arrangement for production of disinfection fluid. In the example of FIG. 2A, this production arrangement comprises or corresponds to the heater 9. As understood from the foregoing, the production arrangement may alternatively or additionally comprise conventional equipment for supplying and dosing at least one suitable cleaning agent into the product water.

[0062] FIG. 3A is a flowchart of an example method 100 that may be performed by a control arrangement to operate a system for generating treatment fluid that includes a WPS 30 and an FPS 10. The system may but need not include a therapy sub-system. An example of the control arrangement is given in FIG. 13 and described further below. The method 100 will be explained with reference to example operational states shown in FIGS 4-6.

[0063] In the example of FIG. 3A, the system is set in either a production mode (PM), a first disinfection mode (DM1), or a second disinfection mode (DM2). In PM, the system is operated to perform a session of generating TF, for example in accordance with FIG. 2A. In DM1, the system is operated to perform a heat disinfection of the FPS. In DM2, the system is operated to perform a disinfection of the WPS. The system may enter the disinfection modes, DM1 and DM2, at any suitable time point when the system is not in PM. For example, the disinfection may be performed after and / or before each session of generating TF, after a predefined plurality of sessions, or at a predefined time interval (once a day, once every second day, once a week, etc.).

[0064] The production mode, PM, involves steps 101-102. In step 101, the WPS is operated to generate PW and to circulate PW in the circulation path 34. As described with reference to FIG. 2A, the WPS 30 generates PW by operating a water purification process on SW. By step 101, a continuous flow of PW is established in the circulation path 34. In step 102, the FPS is operated to obtain PW from the circulation path 34 and to mix PW with one or more concentrates to produce TF. In the example of FIG. 2A, FPS obtains PW on the connecting path CPI, and the mixing is performed by the mixing arrangement 10'. In variants, the FPS obtains PW on the connecting path CP2, or on both CPI and CP2.

[0065] As indicated by dashed lines, the method 100 may include a step 103 of performing a pre-disinfection flush of the FPS, after completed production and before start of disinfection. The purpose of step 103 is to replace existing fluid in the FPS with PW (or disinfection fluid) and to completely prime the FPS prior to start of disinfection. The first disinfection mode, DM1, is performed to disinfect the FPS and involves steps 104-105. In step 104, the WPS is operated to generate PW and circulate PW in the circulation path 34. Step 104 is thus similar to step 101. In some embodiments, as will be described further below, the flow of PW in the circulation path 34 is intermittently stopped during some stages of DM1. In step 105, the FPS is operated to obtain PW from the circulation path 34 on CPI or CP2, or both, to produce a disinfection fluid from PW, and to perform a disinfection of at least part of the FPS by use of the disinfection fluid. As noted with reference to FIG. 2A, the disinfection fluid may be produced by operating the heater 9 to heat PW to a target temperature suitable for heat disinfection. Optionally, a disinfectant may be mixed with PW before or after heating. In a further alternative, the disinfection fluid is produced by mixing non-heated PW with a disinfectant.

[0066] The FPS may be seen to define a fluid path arrangement that includes all durable fluid paths within the FPS, as well as fluid components such as fluid pumps and valves that are associated with the durable fluid paths and exposed to the fluid that flows along the durable fluid paths. In some embodiments of step 105, all of the fluid path arrangement is disinfected by being exposed to the disinfection fluid. However, it is conceivable that one or more parts of the fluid path arrangement is disinfected less frequently than other parts, or that different parts of the fluid path arrangement are disinfected in different instances of DM1. For example, the supply arrangement 11 may be filled with concentrate between sessions of fluid generation and may thereby need less frequent disinfection than other paths of the FPS.

[0067] The FPS may also include one or more disposable components, such as filters, tubing, connectors, etc. A disposable component may be replaced at a time interval that limits the risk for microbial growth within the disposable component. In some embodiments, the FPS is operable to exclude at least part of its disposable component(s) from being exposed to the disinfection fluid during step 105. In other embodiments, one or more disposable components are exposed to the disinfection fluid in step 105.

[0068] As indicated in FIG. 3A, the FPS may be operated in a plurality of different disinfection states 105a-105n during step 105. The disinfection states 105a-105n are defined to expose different parts of the fluid path arrangement to the disinfection fluid. The use of different disinfection states is motivated when it is difficult or undesirable to simultaneously expose all relevant fluid paths in the fluid path arrangement to the disinfection fluid. For example, the use of different disinfection states may be implemented to limit the consumption of disinfection fluid, or to limit the power consumption during disinfection when the disinfection fluid is heated. Thus, in some embodiments, DM1 comprises a predefined sequence of disinfection states, which differ by exposing at least partly different parts of the FPS to the disinfection fluid.

[0069] The plurality of disinfection states may include one or more states in which the FPS is operated to drive the disinfection fluid through the fluid path arrangement to drain. This type of disinfection state is denoted "single-pass state" herein. The plurality of disinfection states may further include one or more states in which the FPS is operated to circulate the disinfection fluid within the fluid path arrangement. This type of disinfection state is denoted "multi-pass state" herein. Generally, a single-pass state results in significantly higher consumption of disinfection fluid and power, since the disinfection fluid will be directed to drain, and thus discarded, during an exposure time period required to achieve a sufficient disinfection of the related fluid paths. It is realized that the consumption of disinfection fluid and power may be significantly reduced by performing the disinfection of the FPS through a combination of single-pass and multi-pass states.

[0070] FIG. 4 shows an example of disinfection states that may be attained during heat disinfection of the system in FIG. 2A. In section (A), the FPS 10 is operated in a multipass state, and the WPS 30 is operated to pump PW through the circulation path 34. The FPS 10 is operated to obtain PW from the circulation path 34 on CP2, and to heat PW by the heater 9 while circulating the heated fluid within the mixing arrangement 10'. As indicated by a dashed arrow, gas and / or excess fluid may be allowed to leave the FPS 10 via the drain path DPI as PW enters the FPS 10. It is realized that during the circulation of the heated fluid, the heater 9 only needs to supply sufficient energy to balance the heat losses from the mixing arrangement 10' to its surroundings. Power consumption is thus limited in the multi-pass state shown in section (A). In section (B), the FPS 10 is operated in a single-pass state, and the WPS 30 is operated to pump PW through the circulation path 34. The FPS 10 is operated to obtain PW from the circulation path 34 on CP2, and to heat PW by the heater 9 while pumping the heated fluid through the mixing arrangement 10' to the drain 4 on a drain path DPI, which corresponds to the drain line L3, the drain port P3, the connector 3a and the tubing 3 in FIG. 2A. The single-pass state may be performed to disinfect the drain path DPI, which cannot be disinfected in a multi-pass state. In section (C), the FPS 10 is operated to generate a throughflow of disinfection fluid between the first and second connecting paths CPI, CP2 via the circulation path 34, between connection points Cl and C2. The disinfection state in section (C) corresponds to step 105n in the method 100 of FIG. 3A. In the illustrated example, PW is heated by the heater 9 before being pumped into CPI. It is to be understood that the flow of disinfection fluid may instead be reversed. The disinfection state in section (C) of FIG. 4 provides a simple and effective way of ensuring that the FPS 10 is disinfected all the way to its fluid connection to the WPS 30. In some embodiments, only one of the connecting paths CPI, CP2 is used as a transfer path for PW in the production mode, PM. The other connecting path may be seen as an auxiliary line that is provided for the purpose of enabling complete disinfection of the transfer path. It may be preferable to perform step 105n as a multi-pass state, as shown in FIG. 4, to economize with disinfection fluid and heating power. In the illustrated example of section (C), the WPS 30 is operated to stop the flow of PW in the circulation path 34 during step 105n. This will minimize risk that disinfection fluid enters the WPS 30 during step 105n.

[0071] The Applicant has also found that it may be beneficial to block fluid transport from the connecting paths CPI, CP2 to the tank 37 during the disinfection stage in section (C), which corresponds to step 105n in FIG. 3A. Experiments indicate that the heated disinfection fluid may form vapor as it flows in the circulation path 34 between the connection points Cl, C2. If this vapor is diverted into the WPS 30, the amount of disinfection fluid in the FPS 10 will decrease over time. This may disrupt the heating of the disinfection fluid in the FPS 10. The risk that vapor is diverted into the WPS 30 is elevated when the tank 37 is held at atmospheric pressure. To mitigate this risk and to ensure consistent and well-controlled heat disinfection of the FPS 10, the WPS 30 may be configured to selectively block fluid transport from the connection points Cl, C2 to the tank 37 in step 105n. Experiments indicate that such blocking of fluid transport significantly reduces the duration of the heat disinfection of step 105n, for example from 60-100 minutes without blocking to 10-12 minutes with blocking.

[0072] Reverting to FIG. 2B, fluid transport may be blocked by closing at least one of the valves 39, 39'. In some embodiments, the purification device 31' inherently blocks or significantly impedes vapor transport, and the WPS 30 need only include the valve 39 that is arranged downstream of the connection points Cl, C2. This valve 39 is selectively closed during step 105n. In other embodiments, both valves 39, 39' are present and closed during step 105n. As noted above, the valve(s) 39, 39' may be an on / off valve or a variable restrictor. The on / off valve may be normally open and actively operated ("energized") to close the circulation path 34. A variable restrictor includes a restricting element, which is moved to define the flow resistance of the variable restrictor. Typically, the restricting element has a "home position" that allows fluid to flow through the variable restrictor. Such a variable restrictor is actively operated ("energized") to close the circulation path 34.

[0073] The technique of closing the circulation path in step 105n has a number of technical advantages. The disinfection time may be significantly reduced, which allows for quicker turnaround times in the disinfection cycle, thereby improving overall operational efficiency. The disinfection process is rendered reliable and consistent to ensure that the disinfection is achieved every time. By preventing vapor escape, water loss during the disinfection process is minimized. Temperature fluctuations that might compromise the disinfection process are mitigated. The impact of varying environmental conditions and atmospheric pressures on the disinfection process is mitigated, so that disinfection remains effective regardless of external factors. The operational reliability of the WPS and the FPS is improved, reducing the likelihood of unexpected downtime or failures. The reduction in disinfection time and water loss translates to cost savings in both energy and water usage. Last but not least, the technique helps ensure compliance with health and safety regulations regarding water quality.

[0074] In some embodiments, the disinfection state (C) in FIG. 4 (step 105n) is the final or concluding disinfection state of the first disinfection mode, DM1. In other words, DM1 is concluded by disinfecting all fluid paths that extend between FPS 10 and WPS

[0075] 30. After step 105n, the FPS 10 will not obtain PW from the WPS 30 until it is again time for the FPS 10 to enter PM. This will ensure the microbial integrity of the FPS between PMs. In the alternative of performing step 105n earlier during DM1, any disinfection state that follows upon step 105n will obtain PW from the WPS 30 via CP1 / CP2, which may thereby be subjected to microorganisms from the WPS 30.

[0076] Reverting to FIG. 3A, the second disinfection mode, DM2, involves a step 106 of operating the WPS to perform a disinfection of all relevant fluid paths within the WPS, including the circulation path 34, as well as fluid pumps, valves, etc. that are associated with the fluid paths and exposed to the fluid that flows along the fluid paths. An example of DM2 is shown in section (D) of FIG. 4, where the WPS 30 operates the heater 36 to heat PW and circulates the heated PW through the purification arrangement

[0077] 31, including the tank 37, as well as through the circulation path 34. The disinfection of the WPS 30 may be performed in correspondence with the disinfection of the FPS 10, and DM2 may thus include one or more single-pass states and one or more multi-pass states.

[0078] In some embodiments, DM2 is performed after DM1, as shown in FIG. 3 A and FIG. 4. In other words, the disinfection of the FPS 10 has been completed when the disinfection of the WPS 30 is started. This has the advantage of decoupling the disinfection of the FPS from the disinfection of the WPS, which in turn reduces eliminates the risk for cross-contamination between the FPS and the WPS.

[0079] FIG. 3B is a flow chart of a procedure that may be performed during step 105 of the method 100 in FIG. 3A. In the illustrated example, the procedure comprises steps 201-205, which each represents a disinfection state. Thus, steps 201-205 correspond to steps 105a-105n in FIG. 3A. The steps 201-205 in FIG. 3B will be described with reference to an example FPS 10 in FIG. 7. The FPS 10 is arranged within a housing 50 that exposes a plurality of ports, including a supply or output port Pl for output of treatment fluid, a first drain port P3 and a second drain port P3'. The FPS comprises a main fluid line ("main line") LI, which extends from a valve V4 to the supply port Pl. A supply arrangement 11 is arranged in the main line LI and is operable to supply one or more concentrates into the main line LI. One or more mixing devices 14 is arranged in the main line LI downstream of the supply arrangement 11, and a fluid pump FP1 is arranged downstream of the mixing device(s) 14 to define the flow rate in the main line LI. A heater 9 is arranged in the main line LI intermediate the supply arrangement 11 and the mixing device(s) 14. A filter arrangement 16 is located downstream of the fluid pump FP1 and configured to purify incoming fluid into a high-quality, microbiologically safe fluid. The filter arrangement 16 is provided to remove microorganisms and endotoxins from the treatment fluid before the treatment fluid is provided to the supply port PL In a non-limiting example, the filter arrangement 16 has a log reduction value (LRV) of 14 for CFU (Colony Forming Units) and 7 for EU (Endotoxin Units). In some embodiments, the filter arrangement 16 includes a sterilizing ultrafilter and / or or a sterilizing grade filter, which are well-known in the art. In some embodiments, the filter arrangement 16 comprises a plurality of ultrafilters or sterilizing grade filters connected in series. In some embodiments, the filter arrangement 16 is employed to achieve "ultrapure" treatment fluid, for example with a total viable bacteria count of less than 1 CFU / 1,000,000 treatments, and a concentration of endotoxins of less than 0.03 EU / mL.

[0080] The FPS 10 further comprises a plurality of additional fluid lines. Fluid line L6 is a return line that extends from a valve VI 1 in the main line LI, downstream of the filter arrangement 16, to the valve V4 in the main line LI, upstream of the supply arrangement 11. Further, a first drain line L3 extends from a valve VI 5' in the return line L6 to the first drain port P3. An intermediate line LI 3 extends to the valve VI 5' from a valve V8 in the main line LI, intermediate the fluid pump FP1 and the filter arrangement 16. A second drain line L4 extends from the supply port Pl to the second drain port P3'. The first connecting path CPI extends between the connection point Cl and a junction JI on the return line L6. A valve VI is arranged in the connecting path CPI. The second connecting path CP2 extends between the connection point C2 and the valve V4. In the following, the valves in the FPS are collectively referred to as a "valve arrangement" and are designated by [V] as shown in FIG. 7. In the following, when the valve arrangement is stated to open a specific fluid line or flow path, it is implied that other available fluid lines or flow paths are closed. The FPS 10 in FIG. 7, to perform heat disinfection in accordance with the steps in FIG. 3B, may be operated in accordance with the AO concept. This means that the heat disinfection is performed to achieve a predefined AO value. As noted above, the AO value is a function of fluid temperature and exposure time. Here, the fluid temperature is given at the coldest location in the fluid path to be disinfected in the respective disinfection state. This fluid temperature is also denoted "heat disinfection temperature" herein. The heat disinfection temperature may or may not differ between disinfection states. In some embodiments, for a given heat disinfection temperature, the duration of the respective disinfection state is determined so as to achieve the predefined AO value. The heat disinfection temperature will be attained at different locations in single-pass states compared to multi-pass states, as will be described below.

[0081] For heat disinfection, it may be desirable to minimize the extent of the flow paths through with the heated fluid is circulated within the FPS in a multi-pass state. This will reduce the power consumption of the heater 9, by reducing the heat losses from the heated fluid to the surroundings. It should be understood that in a multi-pass state, any non-heated PW in the fluid path arrangement of the FPS is first heated to the heat disinfection temperature. Once the heat disinfection temperature has been reached, the heater 9 only needs to use enough power to balance the heat losses as the heated PW circulates in the fluid path arrangement. If the warm-up phase elevates the fluid temperature from a starting temperature (for example, 25 °C) directly to the heat disinfection temperature (for example, 90°C) when fluid passes the heater 9, the power consumption may become excessive. This problem may be mitigated by performing a slower heating of the circulating fluid, for example by the heater 9 being open-loop controlled to a fixed power that is equal or less than a power constraint. When the fluid temperature has been increased sufficiently, the control mode may be switched to closed-loop control with temperature feedback.

[0082] It may be desirable to use a lower flow rate of the heated fluid in a single-pass state compared to a multi-pass state, to thereby reduce the energy consumption per unit time when the heated fluid is pumped to drain in the single-pass state. However, the flow rate of the heated fluid cannot be lowered to such an extent that the heat losses cause the temperature at the coldest location to become too low.

[0083] Turning to FIG. 3B, DM1 comprises a step 201, in which the system is set in a first disinfection state, DS1. In DS1, the system is configured to perform a disinfection of a drain path of the FPS. DS1 is thus a "drain path disinfection state". DS1 is a singlepass state. An example of DS1 is shown in section (B) of FIG. 4, where the drain path DPI is disinfected. In the FPS 10 of FIG. 7, step 201 involves operating the valve arrangement [V] to open (by valve V4) the main line LI to CP2 to admit PW into the FPS 10. Further, the valve arrangement [V] is operated to define (by valve V15') a drain path that includes the intermediate line LI 3, the drain line L3 and any tubing that is connected to the drain port P3 and extends to the drain (cf. FIG. 2A). Still further, the valve arrangement [V] is operated to open (by valve V8) fluid communication between the main line LI and the drain path. In the example of FIG. 7, the drain path extends from the main line LI at a location intermediate the fluid pump FP1 and the filter arrangement 16. Step 201 further involves operating the fluid pump FP1 to drive the disinfection fluid along the main line LI into the drain path. Here, the disinfection fluid is formed by operating the heater 9 to heat the PW that enters the main line LI from CP2 via valve V4. The drain path may be disinfected all the way to the outlet at the drain 4 or to any other location along the drain path.

[0084] In DS1, being a single-pass state, the lowest disinfection fluid temperature will occur at the farthest end of the path to be disinfected, for example at the outlet to the drain 4. The heat disinfection temperature may thus be measured by a temperature sensor (not shown) located at the farthest end. Alternatively, the heat disinfection temperature may be determined based on an upstream fluid temperature, which is measured by a temperature sensor (not shown) in the FPS, and an estimation of the heat losses between the temperature sensor and the farthest end.

[0085] By step 202, the system is set in a second disinfection state DS2. In DS2, the system is configured to perform a disinfection of the supply arrangement 11. DS2 is denoted "supply arrangement disinfection state" or "supply disinfection state". In DS2, the disinfection fluid is circulated through the supply arrangement 11 by use of a return path in the FPS 10. DS2 is thus a multi-pass state. Section (A) of FIG. 4 may be seen to represent the system in DS2. In the FPS 10 of FIG. 7, step 202 involves operating the valve arrangement [V] to define a return path that extends from a location in the main line LI upstream of the filter arrangement 16 to the main line LI upstream of the supply arrangement 11, and to open the main line LI to the return path. Thus, the return path extends from valve V8 along line LI 3 to valve VI 5', and from valve VI 5' along line L6 to valve V4. Step 202 further involves operating the fluid pump FP1 to drive the disinfection fluid along the main line LI into the return path at valve V8, and back into the main line LI at valve V4. The disinfection fluid is formed by operating the heater 9 to heat the PW that is circulated within the FPS.

[0086] In DS2, which is a multi-pass state, the lowest fluid temperature is likely to occur in the main line LI immediately upstream of the heater 9. The heat disinfection temperature may thus be measured by a temperature sensor (not shown) located intermediate the supply arrangement 11 and the heater 9. If such a temperature sensor is not present, the heat disinfection temperature may be estimated based on a temperature measured elsewhere in the FPS and / or based on data on the power consumption of the heater 9 and the fluid flow rate.

[0087] By step 203, the system is set in a third disinfection state DS3. In DS3, the system is configured to perform a disinfection of the filter arrangement 16. DS3 is denoted "filter arrangement disinfection state" or "filter disinfection state". In DS3, the disinfection fluid is circulated through the filter arrangement 16 by use of a return path within the FPS 10. DS3 is thus a multi-pass state. In the FPS 10 of FIG. 7, step 203 involves operating the valve arrangement [V] to open (by valve VI 5') the return line L6 from the main line LI downstream of the filter arrangement 16 to the main line LI upstream of the supply arrangement 11. Further, the valve arrangement [V] is operated to open (by valves V4, VI 1) fluid communication between the main line LI and the return line L6. Also, the valve arrangement [V] is operated to open (by valve V8) for flow in the main line LI between valves V4 and VI 1. Step 203 further involves operating the fluid pump FP1 to drive the disinfection fluid along the main line LI into the return line L6 and back to the main line LI. The disinfection fluid is formed by operating the heater 9 to heat the PW that is circulated within the FPS. In DS3, like in DS2, the heat disinfection temperature is likely to occur in the main line LI immediately upstream of the heater 9.

[0088] By step 204, the system is set in a fourth disinfection state DS4. In DS4, the system is configured to perform a disinfection of the outlet port Pl, the terminal end of the main line LI leading up to the outlet port Pl, as well as the drain line L4 and the drain port P3'. DS4 is an "outlet port disinfection state". DS4 is a single-pass state. In the FPS 10 of FIG. 7, step 204 involves operating the valve arrangement [V] to open (by valve V4) the main line LI to the first connecting path CP2 to admit PW into the FPS. Further, the valve arrangement [V] is operated to open (by valves V8, VI 1) the main line LI to the outlet port PL The fluid pump FP1 is operated to drive the disinfection fluid along the main line LI through the outlet port Pl into the drain line L4 for disposal of the disinfection fluid. The disinfection fluid is formed by operating the heater 9 to heat the PW that enters the main line LI from CP2 via valve V4. The drain line L4 may be disinfected to the drain port P3'. It is also conceivable that the disinfection extends to at least part of a tubing that is connected to the port P3'. In DS4, like in DS1, the lowest fluid temperature will occur at the farthest end of the fluid path to be disinfected.

[0089] In the example of FIG. 7, the outlet port Pl may be configured to automatically close the drain line L4 when the port Pl is connected to a connector (cf. 21a in FIG. 2A), and to automatically open a passage between the main line LI and the drain line L4 when the port Pl is disconnected. Alternatively, the port Pl may be manually or electromechanically operable to open the passage in DS4.

[0090] The flow path in DS4 need not pass the filter arrangement 16. In the example of FIG. 7, step 204 may involve operating the valve arrangement [V] to define a singlepass flow path from C2 along CP2 into the main line LI via valve V4, from valve V8 along line LI 3 to valve VI 5', from valve VI 5' along line L6 to valve VI 1, and from valve VI 1 via the port Pl and drain line L4 to the drain port P3'.

[0091] By step 205, the system is set in a fifth disinfection state DS5. In DS5, the system is configured to perform a disinfection of the water inlet to the FPS. DS5 is thus an "inlet disinfection state". DS5 is a multi-pass state. DS5 corresponds to step 105n in FIG. 3A and is represented by section (C) of FIG. 4. In the FPS 10 of FIG. 7, step 205 involves operating the valve arrangement [V] to open (by valve V4) the main line LI to the connecting path CP2 to admit the product water into the FPS. Further, the valve arrangement [V] is operated to define a return path that extends from valve V8 along line L13 to valve V15', and from valve V15' along line L6 via valve VI and CPI to the connection point CL Further, the fluid pump FP1 is operated to drive the disinfection fluid along the main line LI, into and along the return path to the connection point Cl, along the circulation path 34 from the connection point Cl to the connection point C2, into the connecting path C2, and back to the main line LI at valve V4. In DS5, like in D2, the heat disinfection temperature is likely to occur in the main line LI immediately upstream of the heater 9.

[0092] The ordering of DS1-DS5 during DM1 is merely given as an example. However, as noted above, it is advantageous for DM1 to be terminated by DS5. Further, it may be advantageous to operate the FSP in DS3 before DS4. The filter arrangement 16, which is subjected to disinfection in DS3, may have a significant internal fluid-containing volume. This volume will be filled with heated fluid in DS3. By performing DS4 after DS3 it is possible to use the thermal inertia of the already heated fluid in the filter arrangement 16 to achieve a required heat disinfection temperature in DS4 at a low power consumption by the heater 9. If the FPS is operated in DS4 before DS3, the amount of disinfection fluid that is discarded in DS4 may become excessive since the large non-heated fluid volume in the filter arrangement 16 will be heated in a singlepass state. DS1 need not be the initial state of the FPS during DM1, but may be performed after DS2, DS3 or DS4.

[0093] It is realized that some fluid lines, or part thereof, in the FPS will be subjected to disinfection in more than one disinfection state. Most notably, the main line LI between valve V4 and valve V8 (FIG. 7) will be disinfected in each of DS1-DS5. As indicated in FIG. 3B, the multi-pass states DS2 (step 202), DS3 (step 203) and DS5 (step 205) may involve a step 210, in which the FPS is operated to perform a gas removal procedure, abbreviated DD, to expel gas that is captured and accumulated within the FPS. FIG. 5 shows the DD procedure for the system of FIG. 2A. In the example of FIG. 5, the FPS 10 includes a bubble trap 14' or the like, which is capable of capturing and accumulating gas from passing fluid. Bubble traps are well-known in the field of dialysis and need no further description. In the DD procedure, the WPS 30 is operated to circulate PW through the circulation path 34, and the FPS 10 is operated to obtain PW via the first connecting path CPI. In a variant, PW is obtained via the second connecting path CP2. Further, the FPS 10 is operated to drive the PW through the bubble trap 14' so that accumulated gas G in the bubble trap 14' is entrained in the flow of PW. The entrained gas is expelled from the FPS by the FPS being operated to direct the flow of PW from the bubble trap 14' into the drain path DPI and to the drain 4. In the DD procedure, a refill amount of new PW enters the FPS 10 as the gas is expelled. When the new PW enters the FPS 10, the heater 9 may be operated to heat the new PW to prevent that the fluid temperature of the disinfection fluid falls, since the new PW is much cooler than the heated PW that is circulated in the FPS 10 during the on-going multi-pass state. When the bubble trap is deemed to be sufficiently emptied of gas, for example after a predefined time and / or given by a level sensor associated with the bubble trap, the DD procedure is terminated and the FPS 10 returns to the multi-pass state.

[0094] The gas that is accumulated in the bubble trap 14' may include un-dissolved gas that is released from the PW as it is heated in the FPS. In some implementations, at least some fluid paths in the FPS may be made of a material, for example silicon, which is slightly gas permeable. Thus, it is conceivable that gas may be transported into the fluid path arrangement from the surrounding air by diffusion, which is positively correlated with temperature. Regardless of origin, un-dissolved gas (in the form of gas bubbles) may need to be trapped and discarded from the FPS. If gas bubbles are not sufficiently discarded, the control of the heater 9 may malfunction when gas bubbles are pumped through the heater 9, leading to a risk for temperature overshoots. It is also conceivable that there will be an uncontrolled accumulation of gas in the filter arrangement 16, which may decrease its effectiveness and also prevent proper disinfection of the filter arrangement 16.

[0095] In the FPS 10 of FIG. 7, the bubble trap 14' may be integrated into the mixing device 14, or be a separate device that is installed in the main line LI. In FIG. 3B, step 210 may be performed similar to step 201 (state DS1). It may be advantageous for the bubble trap 14' to be arranged downstream of the heater 9, since the solubility of gas in fluid decreases with increasing temperature.

[0096] The DD procedure of step 210 may also be performed during the single-pass states DS1 and DS4. However, it is conceivable that the FPS operated in the single-pass states to drive the disinfection fluid through the bubble trap 14' so that the accumulated gas G in the bubble trap 14' is entrained in the flow of PW and thereby discarded to drain 4. Thus, a separate DD procedure may not be needed in the single-pass states.

[0097] One advantage of the DD procedure described above is that PW with entrained gas is not directed to drain via the filter arrangement 16. During the DD procedure, relatively cold PW is drawn into the FPS from the WPS. Generally, it is desirable to avoid directing this relatively cold PW into parts of the FPS that already contain heated fluid. This may be especially important for the filter arrangement 16, which may hold a significant volume of fluid. If the filter arrangement 16 is allowed to cool down, the fluid temperature at the inlet of the heater 9 will be reduced for a considerable time. This would in turn cause the AO accumulation rate to slow down significantly (as a result of the exponential temperature dependency of the AO accumulation rate) and hence increase the disinfection time and power consumption.

[0098] It may be desirable to operate the heater 9 during the DD procedure to achieve a target temperature at the outlet of the heater 9 that is high enough to minimize the temperature lowering effects on the AO accumulation rate, but to lower the target temperature enough to decrease risk for heater controller instability, and in particular temperature overshoots. This is particularly relevant when the DD procedure is performed during a disinfection state that passes disinfection fluid through the filter arrangement 16, such as DS3 and DS4.

[0099] Another reason for maintaining a relatively high temperature out from the heater 9 during the DD procedure may be to avoid potential recontamination of the fluid path downstream of the heater 9 from the incoming PW.

[0100] The DD procedure may be performed repeatedly. The time intervals between DD procedures may be set based on testing and performed so that the bubble trap 14' is always operative to capture gas bubbles from passing fluid. Alternatively or additionally, the DD procedure may be triggered by measurements or estimations of the fluid level in the bubble trap 14', for example measured by a level sensor in the bubble trap 14'.

[0101] FIG. 6 shows another procedure that may be performed during heat disinfection of the FPS 10. The rationale behind the procedure in FIG. 6 is that the incoming PW will expand in volume when it is heated, known as thermal expansion. If the fluid path arrangement is formed by relatively stiff tubes or channels, the FPS 10 might not be able to accommodate the increase in fluid volume, resulting in an uncontrolled increase in fluid pressure within the fluid path arrangement as relatively cold PW enters and is heated. Such an uncontrolled pressure increase is undesirable, since it may affect the operation of fluid pump(s) and valves within the FPS 10, and possibly result in leaks. The procedure in FIG. 6 is provided to reduce the impact of the thermal expansion in the FPS 10. This is achieved through the use of the tank 37 in the WPS 30 (FIG. 2A). In some embodiments, the WPS 30 is configured to establish fluid communication with the tank 37 whenever PW is pumped in the circulation path 34. As noted, the tank 37 holds fluid at atmospheric pressure. Thereby, when PW enters the FPS and is heated therein, the fluid pressure in the FPS will be automatically equilibrated against the pressure in the tank 37. As used herein, "equilibrated" implies that the resulting pressure difference between the tank 37 and the FPS corresponds to the pressure drop between the FPS and the tank 37. In other words, since PW is an incompressible fluid, the volume increase caused by the heating in the FPS is accommodated by the tank 37 in the WPS, by an amount of PW being automatically pushed from the FPS via the connecting path CPI (or CP2) towards the tank 37, as indicated by the dotted arrow TEF in FIG. 6. Thus, the tank 37 acts as a compliance vessel for the FPS. In some embodiments, the WPS 30 is configured to set the fluid pressure at the connection points Cl, C2 to be slightly above atmospheric pressure, for example by use of a flow restrictor in the circulation path 34, as readily understood by the person skilled in the art.

[0102] An alternative to the procedure in FIG. 6 is to intermittently operate the FPS 10 to open the drain path DPI to release any pressure increase caused by thermal expansion. In the FPS 10 of FIG. 7, the flow path would be the same as in DS1. The opening of the drain path DPI may be performed periodically or whenever measured fluid pressure in the FPS reaches a threshold level. Compared to the procedure in FIG. 6, the alternative of intermittently opening the drain path may give rise to pressure transients in the FPS that may disturb its operation. Such pressure transients may be counteracted by use of a fixed or variable flow restrictor in the drain path DPI in FIG. 6.

[0103] As noted, the temperature of the disinfection fluid may differ between disinfection states. Thus, each of DS1-DS5 may be assigned a respective predefined target value for the heat disinfection temperature to be attained. Likewise, the DD procedure (FIG. 5) may be assigned a predefined target temperature for the heating of the refill amount. Alternatively, the refill amount may be heated to the heat disinfection temperature of the on-going disinfection state. It is also conceivable that the heat disinfection temperature is deliberately varied during a disinfection state, for example to limit the momentary power consumption of the heater 9. Here, the calculation of the A0 value may account for the variation in heat disinfection temperature, as is well-known in the art.

[0104] The method 100 in FIGS 3A-3B will be further described with reference to a detailed example of an FPS 10 shown in FIGS 8A-8B. For clarity, corresponding components between FIG. 7 and FIGS 8A-8B have the same reference numerals. The FPS is fluidly connected to the circulation path 34 at connection points Cl, C2 by connecting paths CPI, CP2. A main line LI extends from a 3-way valve V4 (FIG. 8A) to a supply port Pl (FIG. 8B). The FPS is arranged within a casing 50, which is configured to expose two ports P2, P2' for connection to a respective concentrate container 7, 7'. The containers 7, 7' contain a respective concentrate that forms part of the treatment fluid. In the following, these concentrates are referred to as first and second concentrates. In the example of PD fluid, one of the concentrates may contain an osmotic agent, such as glucose, and the other concentrate may contain a plurality of different electrolytes. In the example of treatment fluid for use in EC blood therapy, one of the concentrates may be a B concentrate and the other concentrate may be an A concentrate, as is well known in the art. In the illustrated example, the ports P2, P2' are releasably connected to terminal connectors 8a, 8a' on tubing 8, 8' in fluid communication with the containers 7, 7'. Fluid lines ("input lines") L2, L2' extend from the ports P2, P2' to the main line LI. Fluid pumps FP2, FP3 in the input lines L2, L2' are operable to pump the respective concentrate into the main line LI. The ports P2, P2' form an input port arrangement. Port sensors 12, 12' are arranged at the ports P2, P2' to detect when the terminal connectors 8a, 8b are attached to the ports P2, P2'.

[0105] As shown in PIG. 8A, the main line LI extends from the valve V4 through a 3- way valve V5, which is operable to admit the first concentrate into the main line LI, and a 3 -way valve V6, which operable to admit the second concentrate into the main line LI. A pressure sensor SI is arranged intermediate the valves V5, V6. The signal from the pressure sensor SI may be used during TP production (steps 101-102) to provide pressure feedback for controlling the fluid pressure between the valves V5, V6 to a stable value. Pirst and second mixing chambers 13, 14 are arranged in the main line LI downstream of the valve V6. The first mixing chamber 13 is a high-swirl chamber configured to even out any large concentration / density differences that may be caused by the entry of concentrates. The use of two mixing chambers 13, 14 in series has been found to promote efficient mixing of PW and concentrates. Thus, downstream of the second mixing chamber 14, PW and concentrates are mixed to form TP. In an alternative, a single mixing chamber is used. Intermediate the mixing chambers 13, 14 in PIG. 8A, a heater 9 is arranged. Temperature sensors S2, S3 are arranged in the main line LI to sense the fluid temperature upstream and downstream of the heater 9. During TF production (steps 101-102), the heater 9 may be operated by feedback control, based on a signal from the sensor S3, to control the downstream fluid temperature to a predefined temperature, for example 37 °C. A 3-way valve V7 is arranged in the main line LI downstream of the second mixing chamber 14. The valve V7 is connected to a gas removal line L7, which is connected to a top portion of the mixing chamber 14. The valve V7 is operable to selectively connect the gas removal line L7 to the main line LI, for example to release gas accumulated in the second mixing chamber 14 during production of treatment fluid. With reference to FIG. 6, the second mixing chamber 14 implements the bubble trap 14'. A main fluid pump FP1 is arranged in the main line LI downstream of the valve V7. The main fluid pump FP1 sets the flow rate of TF along the main line 1 to the supply port Pl during TF production. Downstream of the fluid pump FP1, a pressure sensor S4, a conductivity sensor S5, and a temperature sensor S6 are arranged in the main line LI. The conductivity sensor S5 may be used to provide conductivity feedback when treatment fluid is generated, as well as during phases when the mixture of PW and concentrates is not delivered through the supply port Pl, for example during composition stabilization before start of TF production. The signal from temperature sensor S6 may be used for temperature compensation of the signal from the conductivity sensor S5, as is well-known in the art.

[0106] Turning now to FIG. 8B, a 3-way valve V8 is arranged in the main line LI downstream of the conductivity sensor S5. The valve V8 is connected to an intermediate line L13, which extends to a junction J5 on a drain line L3. The valve V8 is operable to selectively connect the main line LI to the drain line L3. A 3-way valve V9 is arranged in the main line LI downstream of the valve V8. The valve V9 is connected to a terminal line L9 that extends to a microbial-retentive air filter 15. The valve V9 is operable to selectively connect the main line LI to the air filter 15, for example when the FPS is operated to draw in air for testing the integrity of the filter arrangement, which includes two filtration units UF1, UF2 connected in series. The integrity test is not relevant for the present disclosure and will not be described herein. The filtration units UF1, UF2 may be of any suitable type, including ultrafilters, which are well known in the art. A first filtration unit UF1 is arranged downstream of the valve V9 in the main line LI. Inside UF1, a filter membrane (not shown) is arranged to separate a lumen side (feed side) from a filtrate side (permeate side). UF1 is interposed in the main line LI, so that in the flow path along the main line LI passes the filter membrane. A second filtration unit UF2 is similarly arranged in series with UF1 along the main line LI. An on / off valve V10 is arranged in the main line LI between UF1 and UF2. A pressure sensor S7 is arranged in the main line LI downstream of UF2. The sensor S7 is mainly used for monitoring fluid pressure during the above-mentioned integrity test. The sensor S7 may also be used for sensing obstructions in the tubing 21 (FIG. 2A) during generation of treatment fluid. Also, if the tubing 21 includes a sterile filter, the sensor S7 may be used for monitoring the integrity of the sterile filter. A need for service may be signaled when the fluid pressure at the sensor S7 is above a maximum value or below a minimum value. A 3-way valve VI 1 is arranged in the main line LI between UF2 and the supply port Pl. The valve VI 1 is connected to a return line L6, which extends back to the valve V4 (FIG. 8A). The valve VI 1 is operable to divert an incoming flow on the main line LI into the return line L6, and the valve V4 is operable to selectively admit fluid from the return line L6 into the main line LI.

[0107] The FPS further comprises a return port P4 for receipt of spent treatment fluid ("effluent"). A drain line L4 extends from the port P4 to a second drain port P3'. Further, a connecting line L12 extends between the supply port Pl and the return port P4. The connecting line 12 enables the terminal end of the main line LI and the supply port Pl to be disinfected.

[0108] In the illustrated example, the FPS includes additional fluid lines and valves that are used for enabling flushing of the lumen side of UF1 and UF2. Specifically, a fluid line LI 1 is connected to the lumen side of UF1 and extends to a junction J3 on the return line L6, and a fluid line LIO is connected to the lumen side of UF2 and extends to a junction J2 in fluid line LI L An on / off valve V 12 is arranged in the fluid line Li l between UF1 and the junction J2, and an on / off valve V13 is arranged in the fluid line Li l between junctions J2, J3. Further, the drain line L3 extends from a junction J4 in the return line L6 to the drain port P3, and a respective on / off valve V16, V17 is arranged in the drain line L3 between the junctions J4, J5 and between the junction J5 and the drain port P3.

[0109] The return line L6 includes an on / off valve V14 between the valve VI 1 and the junction J3, and an on / off valve 15 between the junction J4 and the valve V4 (FIG. 8A). In the illustrated example, the return line L6 is further arranged to extend through rinse channels in the fluid pumps FP1, FP2, FP3 (FIG. 8A).

[0110] The first connecting path CPI extends from the connection point Cl to a junction JI on the return line L6. A 3-way valve V2 is arranged in CPI and connected to an intermediate or auxiliary line L8, which extends to the concentrate port P2. A 3-way valve V3 is arranged in CPI and connected to an intermediate or auxiliary line L8', which extends to the concentrate port P2'. Further, an on / off valve VI is arranged in CPI intermediate the valve V3 and the junction JI. The second connecting path CP2 extends from the connection point C2 to the valve V4, which is operable to selectively establish fluid communication between the main line LI and one of CP2 or the return line L6. The 3-way valves in FIGS 8A-8B are of different types depending on desired functionality. FIGS 8C-8D are schematic drawings of two different types of 3-way valves Vx, Vy. Each valve has three valve portions (represented by triangles) which jointly define an internal valve chamber (not shown). The valve portions are connected to a respective fluid line La, Lb, Lc. Valve seats inside the valve portions are designated VS and indicated by an open circle. It is understood that a moveable element (plunger or the like, not shown) is arranged in the valve for engagement with the valve seat VS to close a passage defined by the valve seat VS.

[0111] The valve Vx in EIG. 8C has a single valve seat VS in the valve portion that is connected to line Lc and is always open between lines La and Lb. The valve Vx is operable to selectively open fluid communication with line Lc. The valve Vx is installed as valves V2, V3, V5, V6, Vl l in EIGS 8A-8B. The valve Vx has the specific advantage of facilitating heat disinfection of the internal valve chamber of the valve Vx via La and Lb.

[0112] The valve Vy in EIG. 8D has two valve seats VS in the valve portions that are connected to lines La and Lb. The valve Vy is operable to selectively open fluid communication between lines La and Lc, or between lines Lb and Lc. The valve Vy is installed as valves V4, V7, V8, V9 in EIGS 8A-8B.

[0113] In the following, the operation of the EPS 10 of EIGS 8A-8B in the production mode PM and the disinfection states D1-D5 will be exemplified with reference to PIGS 9-11. Lor clarity of presentation, operating fluid pumps and open valve portions are indicated by filled triangles. It is to be understood that a valve portion is permanently open if it lacks a valve seat. Also, a valve portion with a valve seat may be either normally open or normally closed. Purther, fluid lines through which fluid is flowing are indicated by thicker lines. The flow direction is indicated by solid arrows. In some contexts, the valves in the EPS are collectively referred to as a "valve arrangement".

[0114] PIGS 9A-9B show the EPS 10 in the production mode, PM. The WPS is operated to continuously pump PW through the circulation path 34. All fluid pumps PPI, PP2, PP3 are operating to pump PW, first concentrate and second concentrate through the EPS. Valves V2, V3 are closed, valve VI is open, valve V15 is closed (PIG. 9B), and valve V4 fluidly connects the fluid line L6 to the main line LI. Thereby, PW is pumped by PPI from the connection point Cl through CPI into fluid line L6, and from fluid line L6 into the main line LI. Valve V5 is open, and PP2 pumps the first concentrate from the container 7 through the inlet line L2 into the main line LI. Similarly, valve V6 is open, and PP3 pumps the second concentrate from the container 7' through inlet line L2' into the main line LI. Valve V7 opens the main line LI and closes the gas removal line L7. Thereby, the combination of PW and concentrates flow through the mixing chambers 13, 14 to form TF. The speed of FP1 sets the flow rate of TF through the main line LI. The speeds of FP2 and FP3 are set in relation to the speed of FP1 to achieve a target composition of the treatment fluid. The composition of the treatment fluid may be intermittently or continuously monitored by use of the conductivity sensor S5. The heater 9 may be operated to achieve a predefined target temperature of the treatment fluid. Downstream of FP1, as shown in FIG. 9B, valves V8, V9, V10, Vl l are operated to open the main line LI, while valves V12, V13 are closed, so that TF is directed through UF1, UF2 and is supplied via the supply port Pl, which is connected to a receiving device (not shown, cf. connector 21a in FIG. 2A). The supply port Pl may be configured to automatically open a passage between the main line LI and the connecting line L12 when the receiving device is disconnected from the port Pl, and automatically prevent fluid communication with the connecting line L12 when the receiving device is connected to the port Pl .

[0115] As is well-known to the skilled person, the FPS 10 may be operated in a setup state (not shown) to determine speed ratios between the fluid pumps FP1, FP2, FP3 to achieve the target composition of the treatment fluid. In one example of the setup state, FP1 and FP2 are first operated, and the valve arrangement is operated to admit PW and first concentrate into the main line LI. FP1 may be operated at a speed resulting in a target flow rate to be used in TF production (steps 101-102). The speed of FP2 is adjusted to attain a first predefined conductivity at the sensor S5. Then, FP3 is started and the valve arrangement is operated to also admit second concentrate into the main line LI. The speed of FP3 is adjusted to attain a second predefined conductivity at the sensor S5, where the second predefined conductivity corresponds to the target composition of the treatment fluid. During the setup state, the valve arrangement is operated to direct the fluid from the main line LI to drain, via fluid lines LI 3 and L3. When the target composition is attained, the FPS may be switched to TF production by operating the valve arrangement to direct the treatment fluid through the main line LI to the supply port Pl, as shown in FIGS 9A-9B.

[0116] FIG. 10A shows the FPS 10 in DS1 (step 201 in FIG. 3B). In DS1, the FPS is operated to heat disinfect a drain path that extends from the valve V8 to the drain port P3, and possibly further into a tubing (not shown) that is connected to the drain port P3 and extends to the drain 4 (cf. FIG. 2A). The valve arrangement is operated to establish a single-pass flow path from the circulation path 34 to the drain port P3, and the fluid pump FP1 is operated to drive PW through the single-pass flow path while the heater 9 is operated to heat incoming PW to achieve a target temperature (heat disinfection temperature) at a selected location in the drain path. The duration of DS1 may be determined by an A0 value given as a function of the fluid temperature by a sensor (not shown) located in the drain path. Alternatively, the fluid temperature in the drain path may be estimated based on the temperature measured by the sensor S6 and the fluid flow rate.

[0117] In FIG. 10A, to achieve the single-pass flow path, the valve V4 fluidly connects CP2 to the main line LI, the valves V5, V6 are closed towards the inlet lines L2, L2', the valve V7 closes the main line LI and opens the gas removal line L7 towards the main line LI, the valve V8 closes the main line LI and is open to the intermediate line L13, the valves V15, V16 are closed, and the valve V17 is open. By operating the fluid pump FP1, PW is drawn from C2 along CP2 to the valve V4 and into the main line LI, through the mixing chamber 14 into the gas removal line L7 and back into the main line LI. The fluid pump FP1 then drives the PW along the main line LI via the valve V8 into the intermediate line LI 3, which directs the flow into the drain line L3 and through the drain port P3.

[0118] It may be noted that the single-pass flow path extends through the gas removal line L7. This means that DS1 will drive gas from the mixing chamber 14 to the drain 4. Thus, in the illustrated example, DS1 will inherently involve the DD procedure as exemplified in FIG. 5.

[0119] FIG. 10B shows the FPS 10 in DS2 (step 202 in FIG. 3B). In DS2, the FPS is operated to heat disinfect the supply arrangement 11, which is outlined by dotted lines. Here, the supply arrangement 11 includes the fluid lines L2, L2', L8, L8' and the fluid pumps FP2, FP3 therein. As seen, DS2 is performed when the containers 7,7' have been disconnected from the ports P2, P2', and a passage is opened inside the respective port P2, P2' between the lines L8, L2 and L8', L2'. The respective port P2, P2' may be configured to automatically open the passage when the port P2, P2' is disconnected. The valve arrangement is operated to define a recirculation path in the FPS that includes the fluid lines L2, L2', L8, L8' and the ports P2, P2'. The fluid pumps FP1, FP2, FP3 are operated to circulate PW in the recirculation path. The illustrated example presumes that the recirculation path has been previously primed with PW. During the circulation of PW, the heater 9 is operated to heat the passing fluid. The duration of the circulation may be determined by an A0 value given as a function of the measured temperature by the sensor S2.

[0120] In the illustrated example of FIG. 10B, to achieve the recirculation path, the WPS is operated to stop the flow of PW through the circulation path 34, valves V2, V3, V5, V6 are open, valve V4 fluidly connects the return line L6 to the main line LI, valve V7 opens the main line LI and closes the gas removal line L7, valve V8 closes the main line LI and is open to the intermediate line LI 3, valves V15, V16 are open, valve V17 is closed, and valve VI is open. By operating all fluid pumps FP1, FP2, FP3, product water is circulated along the main line LI to valve V8 and into the intermediate line L13, from the intermediate line L13 into the drain line L3 between junctions J5 and J4, and into the return line L6 between junctions J4 and JI. At junction JI, the flow of product water is split into a first sub-path that extends along the return line L6 to valve V4 and into the main line LI, and a second sub-path that extends along CPI to valves V2 and V3, where the flow is bifurcated into a first flow through the fluid line L8', the port P2', the fluid line L2' to valve V6 and into the main line LI, and a second flow through the fluid line L8, the port P2, the fluid line L2 to valve V5 and into the main line LI.

[0121] In a variant, the FPS is operated as described for FIG. 10B, but the WPS is operated to circulate PW on the circulation path 34. In such a variant, the WPS may be configured to generate an overpressure that is exerted onto the FPS to prevent PW from flowing from the FPS, along CPI, back to the circulation path 34 and into the WPS. Such overpressure may be generated by a flow restrictor in the circulation path 34, as readily understood by the person skilled in the art.

[0122] FIGS 10C-10E show the FPS 10 in three sub-states DS3a-DS3c that are attained by the FPS in DS3 (step 203 in FIG. 3B). In DS3, the FPS is operated to heat disinfect the filter arrangement 16, which is outlined by dotted lines in FIG. 10C. In the illustrated example, the filter arrangement 16 comprises UF1, UF2 and associated fluid lines. The reason for the three sub-states DS3a-DS3c is to enable all parts of the two filtration units UF1, UF2 to be heat disinfected. Thus, in each sub-state, the valve arrangement is operated to define a recirculation path within the FPS, with the different recirculation paths including partly different parts of the filter arrangement 16. As PW is circulated in the respective recirculation path, the heater 9 is operated to heat the passing product water. The illustrated example presumes that the recirculation path has been previously primed with PW. In each sub-state, the duration of the circulation may be determined by an A0 value given as a function of the measured temperature by the sensor S2.

[0123] In FIG. 10C, to achieve the recirculation path, valve VI is closed, the valve V4 fluidly connects the return line L6 to the main line LI, valve V7 opens the main line LI and closes the gas removal line L7, valve V8 opens the main line LI and closes the intermediate line L13, valve V9 opens the main line LI and closes the terminal line L9, the valve V10 is open, valves V12, V13 are closed, valve Vl l is closed to the main line LI towards the port Pl, valves V14, V15 are open, and valve V16 is closed. By operating the fluid pump FP1, PW is circulated along the main line LI through UF1 and UF2 and via the valve Vl l through the return L6 back to the valve V4. To give a better understanding of the flow paths through UF1 and UF2, reference is made to the schematic side view of an ultrafilter 60 in FIG. 11C. The ultrafilter 60 comprises a cylindrical housing 61 fitted with end caps 64a, 64b to define an enclosed space. A filter membrane 62 is arranged in the enclosed space to define a lumen (or feed) chamber or side 63a and a filtrate (or permeate) chamber or side 63b. The lumen chamber 63a has an inlet 65a and an outlet 65b, and the filtrate chamber 63b has an outlet 66. To achieve filtration, the outlet 65b is closed, and a pressurized fluid is admitted into the lumen chamber 63a via the inlet 65a. Thereby, fluid will pass the membrane 62 and filtered fluid will leave the ultrafilter 60 via the outlet 66.

[0124] In FIG. 10D, to achieve the recirculation path, valve V13 is opened and valve V14 is closed, while all other valves remain unchanged compared to FIG. 10C. Thereby, during circulation, PW is directed through the lumen chamber of UF2 (cf. 63a in FIG. 11C) into fluid line L10, from fluid line L10 to fluid line Li l, and from fluid line Li l into the return line L6.

[0125] In FIG. 10E, to achieve the recirculation path, valve V12 is opened and valve V10 is closed, while all other valves remain unchanged compared to FIG. 10D. Thereby, during circulation, PW is directed through the lumen chamber of UF1 (cf. 63a in FIG. 11C) into fluid line Li l, and from fluid line Li l into the return line L6.

[0126] It is realized that all parts of the filter arrangement 16 have been heat disinfected when the FPS has completed each of DS3a-DS3c. It may be noted that DS3a-DS3c may be attained in any order.

[0127] FIG. 10F shows the FPS 10 in DS4 (step 204 in FIG. 3B). In DS4, the FPS is operated to heat disinfect the supply port Pl and associated paths, including a second drain path that includes the connecting line L12 and the drain line L4. The valve arrangement is operated to establish a single-pass flow path from the circulation path 34 to the drain port P3', and the fluid pump FP1 is operated to drive PW through the singlepass path while the heater 9 is operated to heat incoming PW to achieve a target temperature (heat disinfection temperature) at a selected location in the second drain path. The duration of DS4 may be determined by an A0 value given as a function of the fluid temperature by a sensor (not shown) located in the second drain path. Alternatively, the fluid temperature in the drain path may be estimated based on the temperature measured by the sensor S6 and the fluid flow rate.

[0128] In FIG. 10F, to achieve the single-pass flow path, valve V4 fluidly connects CP2 to the main line LI, valves V5, V6 are closed towards the inlet lines L2, L2', valve V7 opens the main line LI and is closed towards the gas removal line L7, valve V8 opens the main line LI towards the port Pl and is closed towards the intermediate line L13, valve V9 opens the main line LI and is closed towards the terminal line L9, valve V10 is open, valve VI 1 opens the main line LI, and valves V12, V13, V14 are closed. The supply port Pl is configured to open an internal passage (not shown) between the main line LI and the connecting line L12 when the port Pl is disconnected and closed. Similarly, the return port P4 is configured to open an internal passage (not shown) between the connecting line L12 and the drain line L4 when the port P4 is disconnected and closed. In FIG. 10F, both ports Pl, P4 are disconnected and closed, and the singlepass flow path extends from the port Pl, via the connecting line L12 and the port P4, to and through the drain line L4. By operating the fluid pump FP1, PW is driven from C2 along CP2 to valve V4 and into the main line LI to the supply port Pl, and via the connecting line L12 and the drain line L4 to the drain port P3'.

[0129] It is to be noted that the single-pass flow path in DS4 may have any extent through the filter arrangement 16, for example as shown in FIG. 10D or FIG. 10E. The single-pass flow path in FIG. 10F has the advantage of passing the disinfection fluid through the filter membranes of UF1 and UF2. The filter membranes form microbial barriers and minimize the risk for microbial exposure at the supply port Pl, which may be regarded as the most micro-critical part of the FPS.

[0130] FIG. 10G shows the FPS 10 in DS5 (step 205 in FIG. 3B). The fluid pump FP1 is operating to pump PW through the FPS, whereas fluid pumps FP2, FP3 are stopped. Valves V2, V3, V5, V6 are closed. The valve arrangement is operated to define a recirculation path in the FPS that includes the connection points Cl, C2. In the illustrated example, to achieve the recirculation path, valve V4 fluidly connects CP2 to the main line LI, valve V7 opens the main line LI and closes the gas removal line L7, valve V8 closes the main line LI and is open to the intermediate line L13, valves V15, V16 are open, valve V17 is closed, and valve VI is open. During the circulation of PW, the heater 9 is operated to heat the passing PW. The duration of the circulation may be determined by an A0 value given as a function of the measured temperature by the sensor S2.

[0131] In the example of FIG. 10G, the recirculation path bypasses the filtration arrangement by a return path that extends from the main line LI at a location upstream of the filter arrangement (at valve 8) via the intermediate line LI 3, the drain line L3, and the return line L6 to valve V4. In a variant, the recirculation path includes the filtration arrangement by having a return path that extends from a location downstream of the filter arrangement to valve V4. In this variant, the disinfection fluid may be directed through the filter arrangement 16 in accordance with any one of FIGS 10C- 10E.

[0132] It should be emphasized that the system in FIGS 8A-8B is merely given as a nonlimiting example. Likewise, the states shown in FIGS 10A-10G are implementation examples. In a variant, state DS3 may be implemented to also include the function of state DS4. Such an variant is shown in FIG. 10H with reference to a different system configuration. The FPS in FIG. 10H differs from the FPS in FIG. 8B by the available flow paths upstream and downstream of the filter arrangement 16. As seen in FIG. 10H, the connecting line L12 has been moved to extend between the outlet port Pl and the return line L6, to junction J3. Further, the 3-way valve VI 1 has been removed and the on / off valve V14 has been moved to the main line LI downstream of the filter arrangement 16. A new connecting line L4' is arranged to extend between the return port P4 and a junction J5' on the intermediate line L13.

[0133] FIG. 10H shows the FPS in sub-state DS3a, which is a multi-pass state performed as part of DS3 for heat disinfection of the filter arrangement 16 (cf. sub-state DS3a in FIG. 10C). In FIG. 10H, to achieve the recirculation path, valve VI is closed, valve V4 fluidly connects the return line L6 to the main line LI, valve V7 opens the main line LI and closes the gas removal line L7, valve V8 opens the main line LI and closes the intermediate line L13, valve V9 opens the main line LI and closes the terminal line L9, valves V10, V14, V15 are open, and valve V16 is closed. The supply port Pl is configured to open an internal passage (not shown) between the main line LI and the connecting line L12 when the port Pl is disconnected and closed. In other words, the supply port Pl is configured to allow a fluid flow between the main line LI and connecting line L12 when the port Pl is disconnected and closed, typically closed by a lid (not shown). The fluid flow may then flow over the outer part of supply port Pl to disinfect it, i.e., to perform a port disinfection. By operating the fluid pump FP1, PW is circulated along the main line LI through UF1 and UF2 and via valve V14 through outlet port Pl into return line L6 and back to valve V4. It is seen that DS3a in FIG. 10H does not only disinfect a path through the filter arrangement 16 but also disinfects the outlet port PL One benefit of performing the disinfection of the outlet port Pl as part of DS3 is that the outlet port Pl is disinfected by a disinfection fluid that has passed the filter arrangement 16 and thereby has the highest possible purity. When the outlet port Pl is disinfected as part of DS3, the dedicated single-pass state DS4 for disinfecting the outlet port Pl (FIG. 3B) can be omitted.

[0134] FIG. 101 shows a state DS4' that may be performed by the FPS of FIG. 10H instead of state DS4. Thus, in the example of FIG. 3B, step 204 would be replaced by a step 204', in which the system is set in state DS4'. In DS4', the system is configured to perform a disinfection of the return port P4 (and optionally drain port P3') as well as lines L4, L4'. DS4' is an "effluent ports disinfection state". In some embodiments, the drain port P3' is located in the FPS 10. In other embodiments, the drain port P3' is an outlet to a drain tank (not shown). In DS4', the valve arrangement is operated to establish a single-pass flow path from the circulation path 34 to the drain port P3' via the effluent port P4, and the fluid pump FP1 is operated to drive PW through the singlepass path while the heater 9 is operated to heat incoming PW to achieve a target temperature (heat disinfection temperature) at a selected location in the second drain path.

[0135] In FIG. 101, to achieve the single-pass flow path, valve V4 fluidly connects CP2 to the main line LI, valves V5, V6 are closed towards the inlet lines L2, L2', valve V7 opens the main line LI and is closed towards the gas removal line L7, valve V8 closes the main line LI and is open to the intermediate line L13, and valves V16, V17 are closed. The return port P4 is configured to open an internal passage (not shown) between the connecting line L4' and the drain line L4 when the return port P4 is disconnected and closed. In other words, the return port P4 is configured to allow a fluid flow between the connecting line L4' and the drain line L4 when the return port P4 is disconnected and closed, typically closed by a lid (not shown). The fluid flow may then flow over the outer part of return port P4 to disinfect it, i.e., to perform a port disinfection. By operating the fluid pump FP1, PW is driven from C2 along CP2 to valve V4 and into the main line LI, and via the connecting line L14 through the return port P4, the drain line L4, and the drain port P3'.

[0136] One advantage of implementing the single-pass state DS4' instead of the singlepass state DS4 is that the impact of heat losses from the filter arrangement 16 is obviated. In state DS4, as exemplified in FIG. 10F, the single-pass flow path extends through the filter arrangement 16 to drain. As noted above, the filter arrangement 16 typically contains a significant amount of fluid. This fluid has been heated in a preceding step (cf. state DS3). During state DS4, the heat losses from the filter arrangement 16 may be significant, and these heat losses need to be at least partly compensated for by the heater 9. Thus, the heat losses from the filter arrangement 14 impacts the power consumption during state DS4. By contrast, the single-pass flow path in step DS4' bypasses the filter arrangement 16, as exemplified in FIG. 101. Thereby, the power consumption is likely to be significantly lower in state D4' compared to state DS4.

[0137] As noted with reference to FIG. 10A, the single-pass flow path that is attained in DS1 will inherently drive gas out of the mixing chamber 14 to the drain 4, when PW is pumped along the single-pass flow path. Thus, the DD (gas removal) procedure of FIG. 5 may be implemented by intermittently switching the FPS from a current disinfection state (for example, DS2, DS3a, DS3b, DS3c, DS4 or DS5) into DSL

[0138] An alternative DD (gas removal) procedure in the FPS of FIGS 8A-8B is shown in FIGS 11A-1 IB. In FIG. 11A, the FPS 10 is operated in a first configuration to move accumulated gas from the mixing chamber 14 to the lumen side of UF1 (cf. 63a in FIG. 11C). In FIG. 1 IB, the FPS 10 is operated in a second configuration to expel the accumulated gas from the lumen side of the UF1 to the drain. The FPS may be operated in the first and second configurations in sequence to achieve a step-wise transport of the accumulated gas from the mixing chamber 14 via UF1 to drain. It is conceivable that the gas storage capacity is larger on the lumen side of UF1 than in the mixing chamber 14. This will enable the FPS to be operated in the first configuration a plurality of times before the FPS is operated in the second configuration, resulting in less fluid being directed to drain in the DD procedure.

[0139] In FIG. 11 A, the valve arrangement is operated to define a recirculation path that extends through the gas removal line L7 and that accumulates gas on the lumen side of UF1. To achieve this recirculation path, valve VI is closed, valve V4 fluidly connects the return line L6 to the main line LI, valve V7 closes the main line LI and opens the gas removal line L7 towards the main line LI, valve V8 opens the main line LI and closes the intermediate line L13, valve V9 opens the main line LI and closes the terminal line L9, valve V10 is open, valve 11 is closed to the main line LI towards the port Pl, valves V12, V13 are closed, valves V14, V15 are open, and valve V16 is closed. By operating the fluid pump FP1, PW is circulated along the main line LI via the gas removal line L7, through UF1 and UF2 and via the valve VI 1 through the return line L6 back to the valve V4.

[0140] In FIG. 1 IB, the valve arrangement is operated to define a single-pass flow path that extends through the lumen side of UF1 to the drain. To achieve this single-pass flow path, valve VI is closed, valve V4 fluidly connects CP2 to the main line LI, valve V7 opens the main line LI and closes the gas removal line L7, valve V8 opens the main line LI and closes the intermediate line L13, valve V9 opens the main line LI and closes the terminal line L9, valve V10 is closed, valves V12, V13 are open, valve V14 is closed, valve V15 is closed, and valves V16, V17 are open. By operating the fluid pump FP1, PW is driven along the main line LI, through the lumen side of UF1 into the fluid line Li l, and from the fluid line LI 1 into the return line L6 at junction J3, from the return line L6 into the drain line L3 at junction J4 and along the drain line L3 to the drain port P3.

[0141] The alternative DD procedure of FIGS 11A-1 IB may be implemented in any FPS that has suitable flow paths, including the FPS of FIG. 7 or the FPS of FIGS 10H-10I.

[0142] FIGS 12A-12B are section views of an example concentrate port P2 as installed in an FPS. FIG. 12A depicts a connected state, in which the port P2 is connected to the terminal connector 8a on the disposable tubing 8. FIG. 12B depicts a disconnected state, in which the port P2 is closed off and thus disconnected from the disposable tubing 8. The port P2 comprises a main body 70 and a lid or cap 71, which is joined to the main body 70 for rotation around a hinge 72. The main body 70 defines a cavity or hole 73. The cavity 73 defines an opening for receiving the connector 8a. The inlet line L2 opens into the internal cavity 73. The auxiliary line L8 opens into the cavity 73 at its perimeter. In the connected state, FIG. 12A, the lid 71 is swung away from the main body 70 to expose the opening to the cavity 73, and the connector 8a is engaged with the opening. Thereby, the tubing 8 is in fluid communication with the inlet line L2 and the auxiliary line L8 via the cavity 73. In the disconnected state, FIG. 12B, the lid 71 is swung into contact with the main body 70 so that a recess 74 in the lid 71 mates with the opening to the cavity 74. The cavity 73 and the recess 74 thereby defines an internal chamber, which is closed to the surroundings and directs incoming fluid to pass from the auxiliary line L8 to the inlet line L2, and vice versa. The lid 71 may be biased towards the main body 70, so that the port P2 is automatically brought into the state in FIG. 12B when the terminal connector 8 is disengaged from the cavity 73. With reference to FIG. 10B, it is realized that the FPS 10, in DS2, is configured to heat disinfect not only the inlet line L2 and the auxiliary line L8, but also the internal chamber of the port P2.

[0143] Generally, any port in the FPS may be configured in correspondence with FIGS 12A-12B, including ports Pl, P2, P2', P3, P3' and P4.

[0144] FIG. 13 is a block diagram of an example control arrangement or sub-system 80, which may be configured to control the operation of the FPS 10 and the WPS 30, and optionally the therapy sub-system 20 (FIGS 1-2). The functionality of the control arrangement 80 may be defined by a combination of software and hardware circuitry, or exclusively by specific hardware circuitry. In FIG. 13, the control arrangement 80 comprises processor circuitry 81, which may be or include a central processing unit (CPU), graphics processing unit (GPU), microcontroller, microprocessor, ASIC, FPGA, or any other specific or general processing device. The control arrangement 80 may operate by executing instructions stored in a computer memory, such as memory 82. The instructions when executed by the processor circuitry 81 may cause the control arrangement 80 to perform any of the methods, procedures and functions described herein, or part thereof. The memory 82 may comprise one or more of a buffer, flash memory, hard drive, removable media, volatile memory, non-volatile memory, random access memory (RAM), or another suitable data storage device. Such a memory 82 is considered a non-transitory computer readable medium. The instructions may be supplied to the control arrangement 80 on a computer-readable medium, which may be a tangible (non-transitory) product (for example magnetic medium, optical disk, readonly memory, flash memory, etc.) or a propagating signal. The control arrangement 80 includes an I / O interface 83a, which may include any conventional communication interface for wired or wireless communication. As shown, the control arrangement 80 is arranged to receive input signals Si and to output control signals Cj. For example, the input signals may be obtained from the sensors S1-S6 and the port sensors 12, 12' in the FPS, and the control signals may be provided to the valves V1-V18 and the fluid pumps FP1-FP3. The control arrangement 80 may comprise a further interface 83b for connection to a feedback device 84 for user interaction. The feedback device 84 may include one or more of a display, a touch screen, a speaker, one or more signaling lamps, a keyboard / keypad, a microphone, a computer mouse, a projector, a camera, etc.

[0145] Below follows a list of some components in the FPS 10 of FIGS 8A-8B and a non-limiting description of their respective purpose / function.

[0146] 9 [heater]: used for controlling fluid temperature in the FPS 10 during fluid generation and heat disinfection.

[0147] 13 [first mixing chamber]: used for reducing concentration / density differences present after dosing of the first and second concentrates into the main line LI.

[0148] 14 [second mixing chamber]: used for achieving a sufficient mixing to provide a stable conductivity measurement by the conductivity sensor S5.

[0149] FP1 [main fluid pump]: operated for driving fluid flow through the main line LI during fluid generation and during heat disinfection.

[0150] FP2 [concentrate pump]: operated for dosing of the first concentrate during fluid generation and for driving heated fluid during heat disinfection.

[0151] FP3 [concentrate pump]: operated for dosing of the second concentrate during fluid generation, and for driving heated fluid during heat disinfection.

[0152] 51 [pressure sensor]: used during fluid generation for monitoring fluid pressure at point of entry of the first and second concentrates into the main line LI, as well as for pressure control feedback and optionally for pressure compensation of the mixing mechanism.

[0153] 52 [temperature sensor]: used for monitoring fluid temperature upstream of the heater 9, at the anticipated coldest point in the fluid path arrangement when heated fluid in circulated in the FPS 10 during heat disinfection, and optionally for feedforward control of the heater 9 during heat disinfection.

[0154] 53 [temperature sensor]: used for sensing fluid temperature downstream of the heater 9 for feedback control of the heater 9 during fluid generation and heat disinfection.

[0155] 54 [pressure sensor]: used for monitoring pressure pulsations caused by FP1 for overheat protection purposes and also to detect elevated counter-pressure caused by malfunctions downstream along the main line LI, for example clogging of UF1 or UF2. S5 [conductivity sensor]: used for conductivity feedback during a setup state for determination of pump speed ratios between FP1, FP2 and FP3, and for conductivity checks during fluid generation.

[0156] S7 [pressure sensor]: used for sensing fluid pressure during ultrafilter integrity test and to detect obstructions downstream the supply port Pl.

[0157] VI [on / off valve]: used for preventing pressure in the WPS 30 to build up in the FPS 10 when idle, which may, e.g., cause rinse channel leakage to surroundings in FP1, FP2 and FP3.

[0158] V2 [3-way valve]: used for enabling a heat disinfection loop through the concentrate port P2 and the inlet line L2 when the container 7 has been detached from the concentrate port P2.

[0159] V3 [3-way valve]: used for enabling a heat disinfection loop through the concentrate port P2' and the inlet line L2' when the container 7' has been detached from the concentrate port P2'.

[0160] V4 [3-way valve]: used for directing product water into the main line LI during fluid generation and heat disinfection, and for including the main line LI in a recirculation path during heat disinfection.

[0161] V5 [3-way valve]: used for closing the transition from the inlet line L2 to the main line LI whenever the first concentrate is not dosed into the main line LI.

[0162] V6 [3-way valve]: used for closing the transition from the inlet line L2' to the main line LI whenever the second concentrate is not dosed to the main line LI.

[0163] V7 [3-way valve]: used for allowing FP1 to draw fluid from two different outlet ports on the second mixing chamber 14, either a top port during gas removal or a bottom port during fluid generation.

[0164] V8 [3-way valve]: used for directing fluid to drain during composition stabilization, and during heat disinfection, as well as to direct gas evacuated from the second mixing chamber 15 to drain without being passed to UF1 and UF2.

[0165] V9 [3-way valve]: used for supplying UF1 and UF2 either with fluid from the main line LI, or air from the air filter 15.

[0166] V10 [on / off valve]: used for stopping fluid flow to the filtrate side of UF1 during flushing of the lumen side of UF1 and during heat disinfection.

[0167] VI I [3-way valve] : used for allowing or prohibiting delivery of treatment fluid via the supply port Pl during fluid generation.

[0168] V12 [on / off valve]: used for closing a flush path on the lumen side of UF1 during fluid generation, and for selectively opening and closing the flush path of UF1 during heat disinfection. V13 [on / off valve]: used for closing a flush path on the lumen side of UF2 during fluid generation, and for selectively opening and closing the flush path of UF2 during heat disinfection.

[0169] V14 [on / off valve]: used for directing gas or fluid to drain during priming and heat disinfection of UF1 and UF2.

[0170] V15 [on / off valve]: used for enabling recirculation during heat disinfection.

[0171] V16 [on / off valve]: used for, together with valve V17, directing fluid downstream of UF1 and UF2 to drain, and for bypassing the filter arrangement 16 during some disinfection states (cf. FIGS 10B and 10G).

[0172] V17 [on / off valve]: used for opening up a path to drain to direct fluid upstream or downstream of UF1 and UF2 to the drain.

[0173] While the subject of the present disclosure has been described in connection with what is presently considered to be the most practical embodiments, it is to be understood that the subject of the present disclosure is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and the scope of the appended claims.

[0174] Further, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results.

[0175] In the following, clauses are recited to summarize some aspects and embodiments as disclosed in the foregoing.

[0176] Cl. A system for providing a treatment fluid for use in dialysis therapy, said system comprising: a first sub-system (30), which comprises a water purification arrangement (31) and is configured to receive supply water and process the supply water by the water purification arrangement (31) to produce product water for use in the dialysis therapy, wherein the first sub-system (30) defines a circulation path (34) and is operable to provide a flow of the product water in the circulation path (34); a second sub- system (10), which is configured to generate the treatment fluid by use of the product water; and a control arrangement (80), wherein the second sub-system (10) is fluidly connected on a first connecting path (CPI) and a second connecting path (CP2) to the circulation path (34), wherein the control arrangement (80) is configured to selectively operate the second sub-system (10) in a production mode, in which the second sub-system (10) obtains the product water on the first or second connecting path (CPI, CP2) and generates the treatment fluid by mixing the product water with one or more concentrates, or a disinfection mode, in which the second sub-system (10) obtains the product water on the first or second connecting path (CPI, CP2), produces a disinfection fluid from the product water, and performs a disinfection of at least part of the second sub-system (10) by use of the disinfection fluid, and wherein the control arrangement (80) is configured to, in the disinfection mode, operate the second subsystem (10) to generate a throughflow of the disinfection fluid in the first and second connecting paths (CPI, CP2) and in the circulation path (34) between the first and second connecting paths (CPI, CP2).

[0177] C2. The system of Cl, wherein said throughflow is generated in the circulation path (34) between a first connection point (Cl), at which the first connecting path (CPI) is fluidly connected to the circulation path (34), and a second connection point (C2), at which the second connecting path (CP2) is fluidly connected to the second connecting path (CP2).

[0178] C3. The system of Cl or C2, wherein the control arrangement (80) is configured to, while the second sub-system (10) is operated to generate said throughflow of the disinfection fluid in the first and second connecting paths (CPI, CP2) and in the circulation path (34) between the first and second connecting paths (CPI, CP2), cause the first sub-system (30) to stop the flow of the product water in the circulation path (34).

[0179] C4. The system of any preceding clause, wherein the control arrangement (80) is configured to, while the second sub-system (10) is operated to generate said throughflow of the disinfection fluid in the first and second connecting paths (CPI, CP2) and in the circulation path (34) between the first and second connecting paths (CPI, CP2), cause the first sub-system (30) to block fluid transport in the circulation path (34).

[0180] C5. The system of any preceding clause, wherein the control arrangement (80) is configured to, while the second sub-system (10) is operated to generate said throughflow of the disinfection fluid in the first and second connecting paths (CPI, CP2) and in the circulation path (34) between the first and second connecting paths (CPI, CP2), cause the first sub-system (30) to block fluid transport from the first and second connecting paths (CPI, CP2) along the circulation path (34) to a tank (37) in the first sub-system (30).

[0181] C6. The system of any preceding clause, wherein the control arrangement (80) is configured to operate the second sub-system (10) to produce the disinfection fluid by heating the product water to a heat disinfection temperature and / or by adding a cleaning agent to the product water. C7. The system of any preceding clause, wherein the disinfection mode comprises a predefined sequence of disinfection states, which differ by exposing at least partly different parts of the second sub-system (10) to the disinfection fluid.

[0182] C8. The system of C7, wherein the disinfection mode is terminated by a final disinfection state, in which control arrangement (80) is configured to operate the second sub- system (10) to generate said throughflow of the disinfection fluid in the first and second connecting paths (CPI, CP2) and in the circulation path (34) between the first and second connecting paths (CPI, CP2).

[0183] C9. The system of any preceding clause, wherein the second sub- system (10) comprises a main flow path (LI) to an outlet port (Pl) for treatment fluid, a supply arrangement (11) for supplying one or more concentrates into the main flow path (LI), a heater (9) in the main flow path (LI) downstream of the supply arrangement (11), a fluid pump (FP1) in the main flow path (LI) downstream of the supply arrangement (11), a filter arrangement (16) in the main flow path (LI) downstream of the heater (9) and the fluid pump (FP1), one or more further flow paths (L2-L13), and a valve arrangement ([V]) operable, by the control arrangement (80), to selectively open the main fluid path (LI) to the first and second connecting paths (CPI, CP2), the outlet port (Pl), and the one or more further flow paths (L2-L13).

[0184] CIO. The system of C9, wherein the disinfection mode comprises a filter disinfection state (DS3), in which the control arrangement (80) is configured to operate the valve arrangement ([V]) to open the main flow path (LI) to a return path (L6), which extends from the main flow path (LI) downstream of the filter arrangement (16) to the main flow path (LI) upstream of the supply arrangement (11), and operate the fluid pump (FP1) to circulate the disinfection fluid along the main flow path (LI) and the return path (L6), and back to the main flow path (LI).

[0185] Cl l. The system of CIO, wherein the control arrangement (80) is further configured to, in the filter disinfection state (DS3), operate the heater (9) to maintain, at a first predefined location within the second sub-system (10), the disinfection fluid at a first temperature for heat disinfection.

[0186] C12. The system of CIO or Cl 1, wherein the control arrangement (80) is further configured to, in the filter disinfection state (DS3), operate the valve arrangement ([V]) to configure the return path to extend through the outlet port (Pl).

[0187] C13. The system of any one of C9-C12, wherein the disinfection mode comprises an outlet port disinfection state (DS4), in which the control arrangement (80) is configured to operate the valve arrangement ([V]) to open the main flow path (LI) to at least one of the first and second connecting paths (CPI, CP2) to admit product water into the second sub-system (10), and open the main flow path (LI) to the outlet port (Pl), so that the disinfection fluid is directed along the main flow path (LI) through the outlet port (Pl) into an outlet path (L4) for disposal of the disinfection fluid.

[0188] C14. The system of C13, wherein the control arrangement (80) is further configured to, in the outlet port disinfection state (DS4), operate the heater (9) to heat the product water that is admitted into the second sub-system (10) to attain a second temperature for heat disinfection at a second predefined location within the second subsystem (10).

[0189] C15. The system of C13 or Cl 4 in combination with any one of C10-C12, wherein the control arrangement (80) is configured to enter the outlet port disinfection state (DS4) after the filter disinfection state (DS3).

[0190] Cl 6. The system of any one of C9-C15, wherein the second sub- system (10) comprises an effluent port (P4) for receiving spent treatment fluid, and wherein the disinfection mode comprises a further disinfection state (DS4'), in which the control arrangement (80) is configured to operate the valve arrangement ([V]) to open the main flow path (LI) to at least one of the first and second connecting paths (CPI, CP2) to admit product water into the second sub-system (10), and open the main flow path (LI) to the effluent port (P4), so that the disinfection fluid is directed along the main flow path (LI) through the effluent port (P4) and into an outlet path (L4) for disposal of the disinfection fluid.

[0191] C17. The system of C16, wherein the control arrangement (80) is configured to, in the further disinfection state (DS4'), operate the valve arrangement ([V]) to open the main flow path (LI) to the effluent port (P4) while bypassing the filter arrangement (16).

[0192] Cl 8. The system of any one of C9-C17, wherein the disinfection mode comprises an inlet disinfection state (DS5), in which the control arrangement (80) is configured to operate the valve arrangement ([V]) to open the main flow path (LI) to the second connecting path (CP2) to admit the product water into the second sub-system (10), open the main flow path (LI) to a return path (L13, L6; L6), which extends from the main flow path (LI) upstream or downstream of the filter arrangement (16) to the first connecting path (CPI), and operate the fluid pump (FP1) to circulate the disinfection fluid along the main flow path (LI), the return path (L13, L6; L6), the first connecting path (CPI), the circulation path (34) intermediate the first and second connecting paths (CPI, CP2), the second connecting path (CP2), and back to the main flow path (LI).

[0193] C19. The system of C18, wherein the control arrangement (80) is further configured to, in the inlet disinfection state (DS5), operate the heater (9) to maintain, at a third predefined location within the second sub-system (10), the disinfection fluid at a third temperature for heat disinfection. C20. The system of C18 or C19, wherein the control arrangement (80) is configured to terminate the disinfection mode after the inlet disinfection state (DS5).

[0194] C21. The system of any one of C9-C20, wherein the disinfection mode comprises a supply disinfection state (DS2), in which the control arrangement (80) is configured to operate the valve arrangement ([V]) to open the main flow path (LI) to a further return path (L13, L6), which extends from the main flow path (LI) upstream of the filter arrangement (16) to the main flow path (LI) upstream of the supply arrangement (11), and operate the fluid pump (FP1) to circulate the disinfection fluid along the main flow path (LI), within the supply arrangement (11), along the further return path (L13, L6), and back to the main flow path (LI).

[0195] C22. The system of C21, wherein the control arrangement (80) is further configured to, in the supply disinfection state (DS2), operate the heater (9) to maintain, at a fourth predefined location within the second sub-system (10), the disinfection fluid at a fourth temperature for heat disinfection.

[0196] C23. The system of C21 or C22, wherein the supply arrangement (11) comprises an input port arrangement (P2, P2') for releasable connection to at least one reservoir (7, 7') containing the one or more concentrates, and wherein the control arrangement (80) is configured to, in the supply disinfection state (DS2), operate the supply arrangement (11) to direct the disinfection fluid through the input port arrangement (P2, P2').

[0197] C24. The system of any one of C9-C23, wherein the disinfection mode comprises a drain path disinfection state (DS1), in which the control arrangement (80) is configured to operate the valve arrangement ([V]) to open the main flow path (LI) to at least one of the first and second connecting paths (CPI, CP2) to admit product water into the second sub-system (10), open the main flow path (LI) to a drain path (L13, L3), which extends to a drain outlet (P3) from the main flow path (LI) at a location intermediate the fluid pump (FP1) and the filter arrangement (16), and operate the fluid pump (FP1) to move the disinfection fluid along the main flow path (LI) into the drain path (L13, L3).

[0198] C25. The system of C24, wherein the control arrangement (80) is further configured to, in the drain path disinfection state (DS1), operate the heater (9) to heat the product water that is admitted into the second sub-system (10) to attain a fifth temperature for heat disinfection at a fifth predefined location within the second subsystem (10).

[0199] C26. The system of any one of C9-C25, wherein the second sub- system (10) comprises a bubble trap (14') located in the main flow path (LI) to collect gas bubbles contained in passing fluid, wherein the control arrangement (80) is configured to, in the disinfection mode, intermittently perform a release procedure (210) to expel the thus- collected gas bubbles from the bubble trap (14').

[0200] C27. The system of C26, wherein the control arrangement (80) is configured to, during the release procedure (210), open the main flow path (LI) to at least one of the first and second connecting paths (CPI, CP2) to admit product water into the second sub- system (10), and operate the heater (9) to heat the product water that is admitted into the second sub-system (10) to attain a sixth temperature for heat disinfection at a sixth predefined location within the second sub-system (10).

[0201] C28. The system of C27, wherein the bubble trap (14') is located downstream of the heater (9) in the main flow path (LI).

[0202] C29. The system of any one of C9-C28, wherein the control arrangement (80) is configured to, intermittently or continuously in the disinfection mode, operate the valve arrangement ([V]) to open the main flow path (LI) to at least one of the first or second connecting paths (CPI, CP2) so as to enable a volume increase, caused by heating of the product water, to be accommodated by a compliance vessel (37) in the first sub-system (30), said compliance vessel (37) being in fluid communication with the circulation path (34).

[0203] C30. The system of any one of C9-C29, wherein the control arrangement (80) is configured to, intermittently in the disinfection mode, operate the valve arrangement ([V]) to open the main flow path (LI) to a drain path (L13, L3) so as to release a pressure increase caused by heating of the product water.

[0204] C31. The system of any one of C9-C30, wherein the control arrangement (80) is configured to, after completion of the disinfection mode of the second sub-system (10), operate the first sub-system (30) to perform (106) a disinfection of at least part of the first sub-system (30), said at least part of the first sub-system (30) comprising the circulation path (34).

[0205] C32. A computer-implemented method of operating a system according to any one of C1-C31, said method comprising: operating (102) the second sub-system (10) in the production mode, in which the second sub-system (10) obtains the product water on the first or second connecting path (CPI, CP2) of the first sub-system (30) and generates the treatment fluid by mixing the product water with the one or more concentrates; and operating (105), before or after the production mode, the second subsystem (10) in the disinfection mode, in which the second sub-system (10) obtains the product water on the first or second connecting path (CPI, CP2), produces the disinfection fluid from the product water, and performs the disinfection of at least part of the second sub-system (10) by use of the disinfection fluid, wherein the second subsystem (10) is operated, in the disinfection mode, to generate (105n; 205) the throughflow of the disinfection fluid in the first and second connecting paths (CPI, CP2) and in the circulation path (34) between the first and second connecting paths (CPI, CP2).

[0206] C33. A computer-readable medium comprising instructions which, when executed by processor circuitry (61), causes the processor circuitry (61) to perform the method C32.

Claims

46CLAIMS1. A system for providing a treatment fluid for use in dialysis therapy, said system comprising: a first sub-system (30), which comprises a water purification arrangement (31) and is configured to receive supply water and process the supply water by the water purification arrangement (31) to produce product water for use in the dialysis therapy, wherein the first sub-system (30) defines a circulation path (34) and is operable to provide a flow of the product water in the circulation path (34), a second sub- system (10), which is configured to generate the treatment fluid by use of the product water, and a control arrangement (80), wherein the second sub-system (10) is fluidly connected on a first connecting path (CPI) and a second connecting path (CP2) to the circulation path (34), wherein the control arrangement (80) is configured to selectively operate the second sub-system (10) in a production mode, in which the second sub-system (10) obtains the product water on the first or second connecting path (CPI, CP2) and generates the treatment fluid by mixing the product water with one or more concentrates, or a disinfection mode, in which the second sub-system (10) obtains the product water on the first or second connecting path (CPI, CP2), produces a disinfection fluid from the product water, and performs a disinfection of at least part of the second sub-system (10) by use of the disinfection fluid, and wherein the control arrangement (80) is configured to, in the disinfection mode, operate the second sub-system (10) to generate a throughflow of the disinfection fluid in the first and second connecting paths (CPI, CP2) and in the circulation path (34) between the first and second connecting paths (CPI, CP2).

2. The system of claim 1, wherein said throughflow is generated in the circulation path (34) between a first connection point (Cl), at which the first connecting path (CPI) is fluidly connected to the circulation path (34), and a second connection point (C2), at which the second connecting path (CP2) is fluidly connected to the second connecting path (CP2).

3. The system of claim 1 or 2, wherein the control arrangement (80) is configured to, while the second sub-system (10) is operated to generate said throughflow of the disinfection fluid in the first and second connecting paths (CPI, CP2) and in the circulation path (34) between the first and second connecting paths (CPI, CP2), cause47 the first sub-system (30) to stop the flow of the product water in the circulation path (34).

4. The system of any preceding claim, wherein the control arrangement (80) is configured to, while the second sub-system (10) is operated to generate said throughflow of the disinfection fluid in the first and second connecting paths (CPI, CP2) and in the circulation path (34) between the first and second connecting paths (CPI, CP2), cause the first sub-system (30) to block fluid transport in the circulation path (34).

5. The system of any preceding claim, wherein the control arrangement (80) is configured to, while the second sub-system (10) is operated to generate said throughflow of the disinfection fluid in the first and second connecting paths (CPI, CP2) and in the circulation path (34) between the first and second connecting paths (CPI, CP2), cause the first sub-system (30) to block fluid transport from the first and second connecting paths (CPI, CP2) along the circulation path (34) to a tank (37) in the first sub-system (30).

6. The system of any preceding claim, wherein the control arrangement (80) is configured to operate the second sub-system (10) to produce the disinfection fluid by heating the product water to a heat disinfection temperature and / or by adding a cleaning agent to the product water.

7. The system of any preceding claim, wherein the disinfection mode comprises a predefined sequence of disinfection states, which differ by exposing at least partly different parts of the second sub-system (10) to the disinfection fluid.

8. The system of claim 7, wherein the disinfection mode is terminated by a final disinfection state, in which control arrangement (80) is configured to operate the second sub- system (10) to generate said throughflow of the disinfection fluid in the first and second connecting paths (CPI, CP2) and in the circulation path (34) between the first and second connecting paths (CPI, CP2).

9. The system of any preceding claim, wherein the second sub- system (10) comprises a main flow path (LI) to an outlet port (Pl) for treatment fluid, a supply arrangement (11) for supplying one or more concentrates into the main flow path (LI), a heater (9) in the main flow path (LI) downstream of the supply arrangement (11), a48 fluid pump (FP1) in the main flow path (LI) downstream of the supply arrangement (11), a filter arrangement (16) in the main flow path (LI) downstream of the heater (9) and the fluid pump (FP1), one or more further flow paths (L2-L13), and a valve arrangement ([V]) operable, by the control arrangement (80), to selectively open the main fluid path (LI) to the first and second connecting paths (CPI, CP2), the outlet port (Pl), and the one or more further flow paths (L2-L13).

10. The system of claim 9, wherein the disinfection mode comprises a filter disinfection state (DS3), in which the control arrangement (80) is configured to operate the valve arrangement ([V]) to open the main flow path (LI) to a return path (L6), which extends from the main flow path (LI) downstream of the filter arrangement (16) to the main flow path (LI) upstream of the supply arrangement (11), and operate the fluid pump (FP1) to circulate the disinfection fluid along the main flow path (LI) and the return path (L6), and back to the main flow path (LI).

11. The system of claim 10, wherein the control arrangement (80) is further configured to, in the filter disinfection state (DS3), operate the heater (9) to maintain, at a first predefined location within the second sub-system (10), the disinfection fluid at a first temperature for heat disinfection.

12. The system of claim 10 or 11, wherein the control arrangement (80) is further configured to, in the filter disinfection state (DS3), operate the valve arrangement ([V]) to configure the return path to extend through the outlet port (Pl).

13. The system of any one of claims 9-12, wherein the disinfection mode comprises an outlet port disinfection state (DS4), in which the control arrangement (80) is configured to operate the valve arrangement ([V]) to open the main flow path (LI) to at least one of the first and second connecting paths (CPI, CP2) to admit product water into the second sub-system (10), and open the main flow path (LI) to the outlet port (Pl), so that the disinfection fluid is directed along the main flow path (LI) through the outlet port (Pl) into an outlet path (L4) for disposal of the disinfection fluid.

14. The system of claim 13, wherein the control arrangement (80) is further configured to, in the outlet port disinfection state (DS4), operate the heater (9) to heat the product water that is admitted into the second sub-system (10) to attain a second temperature for heat disinfection at a second predefined location within the second subsystem (10).

15. The system of claim 13 or 14 in combination with any one of claims 10-12, wherein the control arrangement (80) is configured to enter the outlet port disinfection state (DS4) after the filter disinfection state (DS3).

16. The system of any one of claims 9-15, wherein the second sub-system (10) comprises an effluent port (P4) for receiving spent treatment fluid, and wherein the disinfection mode comprises a further disinfection state (DS4'), in which the control arrangement (80) is configured to operate the valve arrangement ([V]) to open the main flow path (LI) to at least one of the first and second connecting paths (CPI, CP2) to admit product water into the second sub-system (10), and open the main flow path (LI) to the effluent port (P4), so that the disinfection fluid is directed along the main flow path (LI) through the effluent port (P4) and into an outlet path (L4) for disposal of the disinfection fluid.

17. The system of claim 16, wherein the control arrangement (80) is configured to, in the further disinfection state (DS4'), operate the valve arrangement ([V]) to open the main flow path (LI) to the effluent port (P4) while bypassing the filter arrangement (16).

18. The system of any one of claims 9-17, wherein the disinfection mode comprises an inlet disinfection state (DS5), in which the control arrangement (80) is configured to operate the valve arrangement ([V]) to open the main flow path (LI) to the second connecting path (CP2) to admit the product water into the second sub-system (10), open the main flow path (LI) to a return path (L13, L6; L6), which extends from the main flow path (LI) upstream or downstream of the filter arrangement (16) to the first connecting path (CPI), and operate the fluid pump (FP1) to circulate the disinfection fluid along the main flow path (LI), the return path (L13, L6; L6), the first connecting path (CPI), the circulation path (34) intermediate the first and second connecting paths (CPI, CP2), the second connecting path (CP2), and back to the main flow path (LI).

19. The system of claim 18, wherein the control arrangement (80) is further configured to, in the inlet disinfection state (DS5), operate the heater (9) to maintain, at a third predefined location within the second sub-system (10), the disinfection fluid at a third temperature for heat disinfection.

20. The system of claim 18 or 19, wherein the control arrangement (80) is configured to terminate the disinfection mode after the inlet disinfection state (DS5).

21. The system of any one of claims 9-20, wherein the disinfection mode comprises a supply disinfection state (DS2), in which the control arrangement (80) is configured to operate the valve arrangement ([V]) to open the main flow path (LI) to a further return path (L13, L6), which extends from the main flow path (LI) upstream of the filter arrangement (16) to the main flow path (LI) upstream of the supply arrangement (11), and operate the fluid pump (FP1) to circulate the disinfection fluid along the main flow path (LI), within the supply arrangement (11), along the further return path (L13, L6), and back to the main flow path (LI).

22. The system of claim 21, wherein the control arrangement (80) is further configured to, in the supply disinfection state (DS2), operate the heater (9) to maintain, at a fourth predefined location within the second sub-system (10), the disinfection fluid at a fourth temperature for heat disinfection.

23. The system of claim 21 or 22, wherein the supply arrangement (11) comprises an input port arrangement (P2, P2') for releasable connection to at least one reservoir (7, 7') containing the one or more concentrates, and wherein the control arrangement (80) is configured to, in the supply disinfection state (DS2), operate the supply arrangement(11) to direct the disinfection fluid through the input port arrangement (P2, P2').

24. The system of any one of claims 9-23, wherein the disinfection mode comprises a drain path disinfection state (DS1), in which the control arrangement (80) is configured to operate the valve arrangement ([V]) to open the main flow path (LI) to at least one of the first and second connecting paths (CPI, CP2) to admit product water into the second sub-system (10), open the main flow path (LI) to a drain path (L13, L3), which extends to a drain outlet (P3) from the main flow path (LI) at a location intermediate the fluid pump (FP1) and the filter arrangement (16), and operate the fluid pump (FP1) to move the disinfection fluid along the main flow path (LI) into the drain path (L13, L3).

25. The system of claim 24, wherein the control arrangement (80) is further configured to, in the drain path disinfection state (DS1), operate the heater (9) to heat the product water that is admitted into the second sub-system (10) to attain a fifthtemperature for heat disinfection at a fifth predefined location within the second subsystem (10).

26. The system of any one of claims 9-25, wherein the second sub-system (10) comprises a bubble trap (14') located in the main flow path (LI) to collect gas bubbles contained in passing fluid, wherein the control arrangement (80) is configured to, in the disinfection mode, intermittently perform a release procedure (210) to expel the thus- collected gas bubbles from the bubble trap (14').

27. The system of claim 26, wherein the control arrangement (80) is configured to, during the release procedure (210), open the main flow path (LI) to at least one of the first and second connecting paths (CPI, CP2) to admit product water into the second sub- system (10), and operate the heater (9) to heat the product water that is admitted into the second sub-system (10) to attain a temperature for heat disinfection at a predefined location within the second sub-system (10).

28. The system of claim 27, wherein the bubble trap (14') is located downstream of the heater (9) in the main flow path (LI).

29. The system of any one of claims 9-28, wherein the control arrangement (80) is configured to, intermittently or continuously in the disinfection mode, operate the valve arrangement ([V]) to open the main flow path (LI) to at least one of the first or second connecting paths (CPI, CP2) so as to enable a volume increase, caused by heating of the product water, to be accommodated by a compliance vessel (37) in the first sub-system (30), said compliance vessel (37) being in fluid communication with the circulation path (34).

30. The system of any one of claims 9-29, wherein the control arrangement (80) is configured to, intermittently in the disinfection mode, operate the valve arrangement ([V]) to open the main flow path (LI) to a drain path (L13, L3) so as to release a pressure increase caused by heating of the product water.

31. The system of any one of claims 9-30, wherein the control arrangement (80) is configured to, after completion of the disinfection mode of the second sub-system (10), operate the first sub-system (30) to perform (106) a disinfection of at least part of the first sub-system (30), said at least part of the first sub-system (30) comprising the circulation path (34).5232. A computer-implemented method of operating a system according to any one of claims 1-31, said method comprising: operating (102) the second sub-system (10) in the production mode, in which the second sub-system (10) obtains the product water on the first or second connecting path (CPI, CP2) of the first sub-system (30) and generates the treatment fluid by mixing the product water with the one or more concentrates, and operating (105), before or after the production mode, the second sub-system (10) in the disinfection mode, in which the second sub-system (10) obtains the product water on the first or second connecting path (CPI, CP2), produces the disinfection fluid from the product water, and performs the disinfection of at least part of the second subsystem (10) by use of the disinfection fluid, wherein the second sub-system (10) is operated, in the disinfection mode, to generate (105n; 205) the throughflow of the disinfection fluid in the first and second connecting paths (CPI, CP2) and in the circulation path (34) between the first and second connecting paths (CPI, CP2).

33. A computer-readable medium comprising instructions which, when executed by processor circuitry (61), causes the processor circuitry (61) to perform the method of claim 32.

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