Apparatus and method for the efficient production of dialysate using forward osmosis

Abstract

Apparatus (1) and method for producing a dialysate, the apparatus (1) comprising a forward osmosis (FO) unit (2) including a feed side (2a) and a draw side (2b) separated by a FO membrane (2c), the feed side (2a) being included in a feed liquid path (3) and the draw side (2b) being included in a draw liquid path (4), the FO unit (2) being configured to receive a dialysis concentrate solution at the draw side (2b) and a spent dialysate solution at the feed side (2a), such that an osmotic pressure difference between the draw side (2b) and the feed side (2a) transports water from the spent dialysate solution through the FO membrane (2c) to the dialysis concentrate solution, thereby diluting the dialysis concentrate solution to a dilute dialysis concentrate solution and dehydrating the spent dialysate solution to a dehydrated spent dialysate solution, and providing (S3) a hydrostatic pressure difference between the draw side (2b) and the feed side (2a) using one or more pressure pumps (7, 32). The apparatus (1) is configured to sense one or more characteristics of the diluted dialysis concentrate solution and / or the dehydrated spent dialysate, sense one or more pressures indicative of a hydrostatic pressure difference between the draw side (2b) and the feed side (2a), and control at least one of a flow rate of the spent dialysate to the feed side (2a), a flow rate of the dialysis concentrate solution to the draw side (2b), and the hydrostatic pressure difference based on the one or more characteristics of the diluted dialysis concentrate solution and / or the dehydrated spent dialysate and the sensed one or more pressures indicative of the hydrostatic pressure difference to produce a diluted dialysis concentrate solution.

Description

[Technical Field]

[0001] <Claiming priority> This application claims priority to and benefits of U.S. Provisional Application No. 63 / 172,857, filed on 9 April 2021, entitled "Method and System for Controlling Forward Osmosis Membrane Pressure Difference," and Swedish Patent Application No. 2151563-0, filed on 21 December 2021, entitled "Apparatus and Method for Efficient Production of Dialysis Fluid Using Forward Osmosis," the entire contents of each of these applications are incorporated herein by reference and relied upon.

[0002] <Technical field> The present invention relates to the production of dialysate using forward osmosis, and more particularly to a case in which consumed dialysate is used as feed fluid and dialysate concentrate is used as draw fluid in a forward osmosis process. [Background technology]

[0003] Renal failure occurs when the kidneys lose their ability to adequately filter waste products from a patient's blood. Waste products accumulate in the body, and over time, toxins become excessive. If left untreated, renal failure can be life-threatening. Reduced kidney function, especially renal failure, is treated with dialysis. Dialysis removes waste products, toxins, and excess water from the body that would otherwise be removed by a normally functioning kidney.

[0004] One type of treatment for renal failure is hemodialysis ("HD"), which generally uses diffusion to remove waste products from a patient's blood. To cause diffusion, a diffusion gradient is created across a semiosmotic dialyzer between the blood and an electrolyte solution called dialysate. HD fluid is typically produced by the dialyzer by mixing a concentrate with purified water.

[0005] Hemofiltration ("HF") is an alternative renal replacement therapy that relies on the convective transport of toxins from a patient's blood. HF is achieved by adding a replacement fluid or substitute fluid to an extracorporeal circuit during treatment. The replacement fluid and the fluid accumulated by the patient during treatment are ultrafiltered throughout the course of HF treatment, providing a convective transport mechanism that is particularly beneficial in removing medium and large molecules.

[0006] Hemodiafiltration ("HDF") is a therapeutic modality that combines convective and diffusion clearance. HDF uses dialysate flowing through a dialyzer, similar to standard hemodialysis, to provide diffusion clearance. Additionally, a replacement solution is delivered directly to an extracorporeal circuit to provide convective clearance. Here, more fluid than the patient's excess fluid is removed from the patient, resulting in increased convective transport of waste products from the patient. The removed excess fluid is exchanged via a replacement or substitute solution.

[0007] Another type of renal failure treatment is peritoneal dialysis ("PD"), in which a dialysis solution, also called dialysate, is injected into the patient's peritoneal cavity via a catheter. The dialysate is in contact with the peritoneum, which is located within the patient's peritoneal cavity. Waste, toxins, and excess water pass from the patient's bloodstream through the capillaries in the peritoneum into the dialysate due to diffusion and osmosis, i.e., an osmotic gradient is created across the membrane. The osmotic agents in the PD dialysate provide the osmotic gradient. Used or consumed dialysate is drained from the patient, removing waste products, toxins, and excess water from the patient. This cycle is repeated, for example, multiple times. PD solutions are typically prepared in a factory and shipped to the patient's home in ready-to-use bags.

[0008] There are various types of peritoneal dialysis therapies, including continuous ambulatory peritoneal dialysis ("CAPD"), automated peritoneal dialysis ("APD"), tidal dialysis, and continuous flow peritoneal dialysis ("CFPD"). CAPD is a manual dialysis treatment in which fluid transport is driven by gravity. If initially filled with used dialysis fluid, the patient manually connects an implanted catheter to a drain to allow used or consumed dialysis fluid to be drained from the patient's peritoneal cavity. The patient then switches the fluid connection so that the patient catheter communicates with a bag of unused dialysis fluid, allowing the unused dialysis fluid to be injected into the patient through the catheter. The patient then disconnects the catheter from the bag of unused dialysis fluid, allowing the dialysis fluid to remain in the peritoneal cavity, where the transport of waste, toxins, and excess water occurs. After the retention period, the patient repeats the manual dialysis procedure, for example, four times a day. If the patient is not initially filled with used dialysis fluid, the sequence instead is patient filling, retention, and draining. Manual peritoneal dialysis requires considerable time and effort from the patient and leaves ample room for improvement.

[0009] Automated peritoneal dialysis ("APD") is similar to CAPD in that the dialysis treatment involves draining, filling, and retention cycles. However, APD machines typically perform the cycles automatically while the patient is asleep. APD machines free patients from having to manually perform treatment cycles and transport supplies during the day. The APD machine is fluidically connected via the patient line to the patient's implanted catheter, a source or bag of unused dialysate, and a fluid drain. The APD machine pumps unused dialysate from the unused dialysate source into the patient's peritoneal cavity through the catheter. The APD machine also allows the dialysate to remain in the patient's peritoneal cavity, enabling the transfer of waste, toxins, and excess water. The source may contain several liters of dialysate, including multiple solution bags.

[0010] Dialysis treatment may be performed at a clinic or remotely, such as at the patient's home. Transporting dialysate adds cost to treatment and has negative environmental impacts. Dialysis fluid storage requires space, and large dialysate bags must be handled by the user. Therefore, there is a need for methods to reduce or eliminate the amount of dialysate transported to the patient's home and manually moved by the patient. [Overview of the project]

[0011] To mitigate the negative consequences identified above from the transport of dialysate to the patient's home, dialysate may be produced from concentrates at the time of care. In the apparatus and methods of this disclosure, forward osmosis (FO) may be used to dilute the dialysate concentrate with water to provide a diluted dialysate concentrate, which may be called a dialysate solution. The dialysate solution may then be mixed with other concentrates to provide a final dialysate that can be used for dialysis treatment to treat a patient, or it may be used as the final dialysate. The final dialysate may be a dialysate for PD, a dialysate for HD or HDF, or an alternative or replacement for HF or HDF. FO utilizes the osmotic pressure difference between the feed fluid and the concentrate as the draw fluid, which is separated by an FO membrane. The osmotic pressure difference is used as an energy source to move water from the feed fluid to the draw fluid, making FO an attractive low-energy alternative. Here, the feed fluid is, in one embodiment, the consumed dialysate, thereby significantly reducing the amount of unused water used for treatment. Generally, the slower the FO process runs, the greater the water extraction. However, the process typically has to meet time constraints for preparing the fluid for use, and therefore the FO process must be executed within a specific timeframe. Thus, there is a need for a method that can increase water extraction efficiency in order to reduce the time required to prepare the dialysate.

[0012] An objective of this disclosure is to mitigate at least some of the shortcomings of the prior art. A further objective is to provide a method for efficient control of water extraction to achieve a desired dilution of a dialysis concentrate in a forward osmosis process.

[0013] These and other objects are at least partially achieved by the apparatus and method according to the independent claims, as well as by the embodiments according to the dependent claims.

[0014] According to a first aspect, which may be combined with any other aspect or part thereof, the present disclosure relates to an apparatus for generating dialysate. The apparatus comprises a draw solution path including one or more concentrate connectors each configured to be connected to a source of dialysate concentrate, a feed solution path including a connector configured to be connected to a source of spent dialysate, and a forward osmosis (FO) unit. The FO unit includes a feed side and a draw side separated by an FO membrane, the feed side being included in the feed solution path and the draw side being included in the draw solution path. The FO unit is further configured to receive the dialysate concentrate on the draw side and the spent dialysate on the feed side, and water is transported from the spent dialysate through the FO membrane to the dialysate concentrate via an osmotic pressure difference between the draw side and the feed side, thereby diluting the dialysate concentrate to a diluted dialysate concentrate and dehydrating the spent dialysate to a dehydrated spent dialysate. The apparatus further comprises one or more property sensors configured to sense one or more properties of the diluted dialysate concentrate and / or the dehydrated spent dialysate, one or more pressure sensors configured to sense one or more pressures indicative of a hydrostatic pressure difference between the draw side and the feed side, and a control device. The control device is configured to cause a flow of the dialysate concentrate to the draw side, cause a flow of the spent dialysate to the feed side, and cause a hydrostatic pressure difference between the draw side and the feed side to be provided using one or more pressure pumps. The control device is further configured to control at least one of the flow rate of the spent dialysate to the feed side and the flow rate of the dialysate concentrate to the draw side, or the hydrostatic pressure difference, and the control is based on one or more properties of the diluted dialysate concentrate and / or the dehydrated spent dialysate and one or more sensed pressures indicative of the hydrostatic pressure difference for creating the diluted dialysate concentrate.

[0015] The extraction of water from spent dialysate in a forward osmosis process can be increased by having a low flow rate of fluid within the FO unit so as to allow for a longer time for the forward osmosis process. However, it is often required to provide the dialysate for a specific duration, which places a limit on how low the flow rate can be and thus how high the efficiency can be. By carefully providing and controlling the hydrostatic pressure difference, the efficiency of the forward osmosis process can be increased and the dilution factor of the dialysis concentrate can be better controlled. The use of one or more pressure pumps to control the hydrostatic pressure enables the control of the hydrostatic pressure even when the flow is small.

[0016] According to a second aspect, which may be combined with any other aspect or part thereof, the present disclosure relates to a method for generating dialysate. The method includes providing a flow of dialysis concentrate liquid to the draw side of a forward osmosis (FO) unit and providing a flow of spent dialysate to the feed side of the FO unit, wherein water is transported from the spent dialysate through the FO membrane to the dialysis concentrate liquid via an osmotic pressure difference between the draw side and the feed side, thereby diluting the dialysis concentrate liquid to a diluted dialysis concentrate liquid and dehydrating the spent dialysate to a dehydrated spent dialysate. The method further includes using one or more pressure pumps to provide a hydrostatic pressure difference between the draw side and the feed side, sensing one or more characteristics of the diluted dialysis concentrate liquid and / or the dehydrated spent dialysate, and sensing one or more pressures indicative of the hydrostatic pressure difference between the draw side and the feed side. The method includes controlling at least one of the flow rate of the spent dialysate to the feed side and the flow rate of the dialysis concentrate liquid to the draw side, or the hydrostatic pressure difference, based on one or more characteristics of the diluted dialysis concentrate liquid and / or the dehydrated spent dialysate and the sensed one or more pressures indicative of the hydrostatic pressure difference, to create the diluted dialysis concentrate liquid.

[0017] In some embodiments, which may be combined with any other embodiments or parts thereof, the control includes controlling the flow rate of consumed dialysate to the feed side based on the available volume of consumed dialysate and the length of the period available to produce a desired amount of diluted concentrate, and controlling the flow rate of dialysate concentrate 15 to the draw side based on the volume of dialysate concentrate required to produce a desired amount of diluted concentrate and the length of the period to provide a desired amount of diluted concentrate at the end of the period. This allows the flow rate to be controlled in the most efficient manner to provide a desired amount of diluted concentrate in a timely manner.

[0018] In some embodiments, which may be combined with any other embodiments or parts thereof, the method includes controlling the hydrostatic pressure difference using one or more pressure pumps based on one or more properties of the diluted dialysis concentrate and / or dehydrated consumed dialysate and one or more sensed pressures indicating a hydrostatic pressure difference. Thus, the hydrostatic pressure may be controlled based on different fluid properties resulting from the FO process and the current hydrostatic pressure.

[0019] In some embodiments, which may be combined with any other embodiments or parts thereof, the method includes controlling a hydrostatic pressure difference using one or more pressure pumps based on one or more sensed pressures to achieve a predetermined hydrostatic pressure difference. In some embodiments, the predetermined hydrostatic pressure difference is the maximum allowable hydrostatic pressure difference. This allows for the achievement of the maximum effect of the hydrostatic pressure.

[0020] In some embodiments, which may be combined with any other embodiments or parts thereof, the method includes controlling the hydrostatic pressure difference using one or more pressure pumps to equalize the properties of a diluted dialysis concentrate and / or dehydrated consumed dialysate, based on the properties of

[0021] In some embodiments, which may be combined with any other embodiments or parts thereof, the method includes controlling the flow rate of the dilution dialysis concentrate using a concentrate pump such that the flow rate of the dilution dialysis concentrate is equal to the inlet flow rate of the dialysis concentrate to the draw side multiplied by a target dilution factor, and controlling the flow rate of the dilution dialysis concentrate using a second pressure pump of one or more pressure pumps. Thereafter, the pumps in the draw fluid path can be controlled to achieve a desired target dilution factor.

[0022] In some embodiments, which may be combined with any other embodiments or parts thereof, the method includes controlling the ratio between a concentrate pump and a second pressure pump to equalize the properties of a diluted dialysis concentrate to a target value of the properties. This allows the draw-side pump to be fine-tuned, for example, based on conductivity, after being controlled based on flow rate, in order to actually achieve the desired target dilution factor, for example, even if the specified concentration of the concentrate is inaccurate.

[0023] In some embodiments, which may be combined with any other embodiments or parts thereof, the method includes controlling the flow rate of consumed dialysate to the feed side 2a and / or the flow rate of dialysate concentrate 15 to the draw side 2b, based on one or more sensed pressures indicating a hydrostatic pressure difference, such that the hydrostatic pressure difference is kept below the maximum allowable hydrostatic pressure difference. This ensures that the hydrostatic pressure difference is kept below the maximum allowable limit, thereby eliminating the risk of damaging the FO membrane.

[0024] In some embodiments, which may be combined with any other embodiments or parts thereof, sensing one or more properties of the diluted dialysis concentrate and / or the dehydrated consumed dialysis fluid includes sensing one or more of the following: the concentration of the diluted dialysis concentrate, the concentration of the dehydrated consumed dialysis fluid, the weighing of the diluted dialysis concentrate by a weighing scale, the weighing of the dehydrated consumed dialysis fluid by a weighing scale, the flow rate of the diluted dialysis concentrate, and the flow rate of the dehydrated consumed dialysis fluid.

[0025] In some embodiments, which may be combined with any other embodiments or parts thereof, one or more pressure pumps include a first pressure pump configured to operate on the consumed dialysate output from the feed side.

[0026] In some embodiments, which may be combined with any other embodiments or parts thereof, the first pressure pump is configured to pump either upstream or downstream. This allows the first pressure pump to control the hydrostatic pressure difference even when the consumed dialysate output from the feed side is a small flow.

[0027] In some embodiments, which may be combined with any other embodiments or parts thereof, one or more pressure pumps include a second pressure pump configured to operate on the dilution dialysate output from the draw side, thereby allowing the hydrostatic pressure difference to be controlled from the draw side.

[0028] In some embodiments, which may be combined with any other embodiments or parts thereof, at least one of the one or more pressure pumps is a non-positive displacement pump.

[0029] In some embodiments, which may be combined with any other embodiments or parts thereof, at least one of the one or more pressure pumps is a positive displacement pump.

[0030] In some embodiments, which may be combined with any other embodiments or parts thereof, the method includes controlling the flow rate of a second or third concentrate to flow into a diluted concentrate solution to form a dialysate. This provides the concentrate required to produce a dialysate.

[0031] In some embodiments, which may be combined with any other embodiments or parts thereof, the method includes providing pure water to a dilution concentrate to form a dialysate. This allows a dialysate to be provided even if the FO process does not provide sufficient dilution.

[0032] In a third aspect, which may be combined with any other embodiment or part thereof, the Disclosure relates to a computer program that includes instructions configured to cause an apparatus according to the first aspect to perform a method according to the second aspect.

[0033] According to a fourth aspect, which may be combined with any other embodiment or part thereof, the Disclosure relates to a computer-readable medium storing a computer program of the third aspect. [Brief explanation of the drawing]

[0034] [Figure 1] This disclosure describes a schematic FO unit according to several embodiments. [Figure 2] This disclosure describes an apparatus for generating a dialysis solution containing an FO unit according to several embodiments of this disclosure. [Figure 3] , [Figure 4] , [Figure 5] Different examples of the FO device used in the apparatus of Figure 1, according to several embodiments of this disclosure, are described below. [Figure 6] Examples of compliance chambers in several embodiments of this disclosure are described. [Figure 7] This is a flowchart showing method steps for generating dialysate according to some embodiments of the present disclosure. [Figure 8] To increase the feed-side pressure of the FO unit in Figures 1 and 2, the results of a test using a non-positive displacement pump as shown in Figure 3 are illustrated. [Figure 9A] , [Figure 9B] This section provides a brief overview of exemplary dialysis systems for peritoneal dialysis and extracorporeal hematopoiesis. [Modes for carrying out the invention]

[0035] This disclosure describes apparatus and methods for efficiently generating dialysate using a combination of flow rate control and hydrostatic pressure control. As discussed herein, the slower the FO processing is performed, the greater the water extraction, thereby making lower flow rates through the FO unit desirable to reduce fluid consumption. Lower fluid consumption reduces the need for excess water and the need for efficient use of the fluid at hand. Hydrostatic pressure control is performed using one or more pressure pumps acting on the outlet flow from the feed side and / or draw side, thereby making it possible to control the hydrostatic pressure difference between the feed side and the draw side, even at low flow rates. The hydrostatic pressure difference may also be referred to herein as the intermembrane pressure difference (TMP). In some embodiments, combined control is performed to extract as much water as possible from the consumed dialysate without impairing or reaching the limits of the apparatus or the fluid provided. The consumed dialysate may also be referred to herein as used dialysate or waste.

[0036] Hereafter, with reference to Figures 1 to 6, the FO device, FO device apparatus, compliance chamber apparatus, and apparatus will be described and the composite control described herein will be implemented to generate dialysate in various embodiments. Subsequently, the method for generating dialysate using the composite control will be described with reference to the flowchart in Figure 7, and this method may be performed by the control device in various embodiments of the control device. Reference numerals that are the same throughout the drawings may not be listed in the text in each embodiment, but nevertheless, for each embodiment, all structures, functions, and substitutes described for such references will be included.

[0037] Figure 1 is a schematic diagram of an FO device 2 that can be used with any of the embodiments described herein. The FO device 2 comprises a feed side 2a and a draw side 2b separated by an FO membrane 2c. The sides may also be referred to herein as compartments or chambers. The FO device 2 typically includes a cartridge enclosing the feed side 2a, the draw side 2b, and the FO membrane 2c. The geometric shape of the FO membrane 2c may be a flat sheet, tubular, or hollow fiber. The FO membrane 2c is a permeable membrane. The FO membrane 2c is designed to be more or less exclusively selective for permeating water molecules, thereby enabling the FO membrane 2c to separate water from all other contaminants. The FO membrane 2c typically has a pore size in the nanometer (nm) range, e.g., 0.5 to 5 nm or less, depending on the solute intended to be blocked. During use, the FO membrane 2c separates the feed solution at the feed side 2a and the draw solution at the draw side 2b. The fluids on these sides typically flow in a counterflow, but may instead flow in a parallel flow. In one embodiment, the flow is a continuous flow and therefore flows without interruption. The FO unit 2 is configured to receive a draw solution, which is the dialysate concentrate, at the draw side 2b and a feed solution, such as consumed dialysate, at the feed side 2a. Water is transported from the consumed dialysate through the FO membrane 2c to the dialysate concentrate via the osmotic pressure difference between the draw side 2b and the feed side 2a, thereby diluting the dialysate concentrate to a diluted dialysate concentrate and dehydrating the consumed dialysate to a dehydrated consumed dialysate. The feed side 2a is an inlet port E through which the consumed dialysate is transported to the feed side 2a. in Then, the dehydrated, consumed dialysate is transported from the feed side 2a to the outlet port E. out The draw side 2b has an inlet port L through which the dialysis concentrate is transported to the draw side 2b. in Then, the diluted dialysis concentrate is transported from the draw side 2b to the outlet port L. outThe feed side 2a is included in the feed liquid pathway 3. The draw side 2b is included in the draw liquid pathway 4. Suitable FO devices for FO device 2 may be provided by, for example, Aquaporin, Asahi Kasei, Berghof, CSM, FTSH2O (trademark), Kork Membrane Systems, Polyfera, Toyobo, Aromatec, and Toray.

[0038] Herein, with reference to Figure 2, an example of an apparatus 1 for generating fluid for dialysis according to some embodiments of the present disclosure is described. Apparatus 1 comprises an FO unit 2 (such as FO unit 2 in Figure 1), a feed fluid path 3, and a draw fluid path 4. A control device 50 is configured to control apparatus 1 to perform a number of procedures. The control device 50 includes a control unit 30, a valve device 20 (20a to 20p), and at least one pump 6, 7, 10, 23, 29, 32. The valve device 20 is arranged and configured to constitute a number of different flow paths of apparatus 1.

[0039] The feed fluid route 3 is configured to supply consumed dialysate to the feed side 2a of the FO unit 2. The feed fluid route 3 begins at the inlet connector Pi and ends at the drain 31. The inlet connector Pi is configured to connect to the consumed dialysate line of the HD or CRRT device to receive the PD patient's catheter, ultimately via the cyclometer, or as described in more detail in relation to Figures 9A and 9B. The feed fluid route 3 also includes a container connector 40a configured to connect to the consumed dialysate container 19. Alternatively, the feed fluid route 3 includes only one of these connectors. In other words, the feed fluid route 3 includes connectors Pi, 40a configured to connect to a source of consumed dialysate. The feed fluid route 3 is connected to the inlet connector Pi and the inlet port E to the feed side 2a. in It includes a feed-side input line 3a positioned between the input connector Pi and the input port E. in The fluid is connected to the feed side inlet line 3a. The input valve 20a is positioned to operate together with the feed side inlet line 3a. The input valve 20a and the inlet port Ein A feed-side input line valve 20b is arranged between the same and operates together with the feed-side input line 3a. The feed liquid path 3 further includes a container line 3b arranged between a container connector 40a and the feed-side input line 3a between the input valve 20a and the feed-side input line valve 20b. Thus, the container line 3b fluidly connects the container connector 40a and the feed-side input line 3a. A feed pump 6 is arranged to operate together with the container line 3b to provide a flow within the container line 3b. In some embodiments, the feed pump 6 is a bidirectional pump. A container valve 20p is arranged between the feed pump 6 and the container 19 to operate together with the container line 3b. A DC line 3c is arranged between the container line 3b and the feed-side input line 3a. Thus, the DC line 3c fluidly connects the container line 3b and the feed-side input line 3a. The DC line 3c is connected to the container line 3b between the container valve 20p and the feed pump 6. The DC line 3c is connected to the feed-side input line 3a between the feed-side input valve 20b and the inlet port E in and the same. A DC line valve 20s is arranged to operate on the DC line 3c. The feed liquid path 3 further includes a discharge line 3d. The discharge line 3d is arranged between the outlet port E of the feed side 2a out and the drain 31. Thus, the discharge line 3d fluidly connects the outlet port E out and the drain 31. A first pressure pump 7 is arranged to operate together with the discharge line 3d to provide pressure to the feed side 2a. A drain valve 20i is arranged on the discharge line 3d between the first pressure pump 7 and the drain 31. In some embodiments, the first pressure pump 7 is a bidirectional pump.

[0040] The feed pump 6 is configured to pump fluid from the container 19 or another supply source at the inlet connector Pi to the feed-side input line 3a, and to provide the consumed dialysate to the feed side 2a. The consumed dialysate is pre-pumped from the patient connected at the inlet connector Pi to the container 19 by pumping it forward using the feed pump 6 and closing the feed-side input line valve 20b and the DC line valve 20s. In some embodiments, to provide the consumed dialysate to the feed side 2a, the feed pump 6 operates in the reverse or opposite direction, opening the container valve 20p, the feed-side input line valve 20b and the discharge valve 20i, and closing the DC line valve 20s. At this time, the consumed dialysate is pumped from the container 19 through the container line 3b to the feed-side input line 3a, and further to the feed side 2a. The dewatered consumed dialysate is then output from the feed side 2a to the discharge line 3d, and further to the drain 31. Alternatively, the feed pump 6 may directly pump the consumed dialysate from the patient or other source connected to the inlet connector Pi by pumping (forward) using the feed pump 6, opening the DC line valve 20s, and closing the container valve 20p and the feed-side input line valve 20b. The consumed dialysate is then pumped to the feed-side input line 3a and further to the feed side 2a via the container line 3b and the DC line 3c. The feed pump 6 is a positive displacement pump, such as a piston pump operating in an open loop (a specific voltage or frequency command from the control device 50 to provide a specific flow rate). Alternatively, the feed pump 6 is a non-positive displacement pump that operates using feedback from a flow sensor 43 to reach a specific flow rate. The flow sensor 43 is connected to the container line 3b between the feed pump 6 and point P1, but instead, it may be connected to the container line 3b on any side of the feed pump 6, except between the container 19 and the connection point of the DC line 3c to the container line 3b.

[0041] The draw fluid pathway 4 is positioned to supply the dialysis concentrate to the draw side 2b (Figure 1). The draw fluid pathway 4 includes one or more concentrate connectors 30a, 30b. Each concentrate connector 30a, 30b is configured to connect to a dialysis concentrate supply source 15, 18. The first concentrate connector 30a is connected to the first concentrate container 15. The second concentrate connector 30b is connected to the second concentrate container 18. The draw fluid pathway 4 begins with the first concentrate connector 30a connected to the first concentrate container 15 and ends with the outlet connector Po. The outlet connector Po can be connected, for example, to the catheter of a PD patient, ultimately via a cyclometer, or to the dialysis line of an HD or CRRT device to deliver the generated dialysis fluid to the patient or device. The draw fluid path 4 further includes a plurality of lines, including a concentrate line 4d, a draw-side input line 4b, a first dilution concentrate line 4e, a second dilution concentrate line 4a, a main line 4f, a draw-side output line 4c, a pure water line 4g, a second concentrate line 4h, and a drain connection line 4i. The concentrate line 4d is located between the first concentrate connector 30a and the connection point P3 between the main line 4f and the draw-side input line 4b. Thus, the concentrate line 4d fluidly connects the concentrate connector 30a, and by extension the concentrate container 15, to the draw-side input line 4b (and the main line 4f). A concentrate valve 20d is positioned to operate on the concentrate line 4d. The draw-side input line 4b is connected to the inlet port L of the draw-side 2b between the connection point P3 with the concentrate line 4d and the draw-side 2b. in It is positioned between the two. Therefore, the draw-side input line 4b is connected to the concentrate line 4d (at connection point P3) and the inlet port L in A fluid connection is established between the two. A draw-side input valve 20h is positioned to operate on the draw-side input line 4b. A concentrate pump 10 is positioned to operate on the concentrate line 4d to provide flow into the concentrate line 4d. The concentrate container 15 contains, for example, a fluid dialysis concentrate. The concentrate pump 10 is positioned and configured to pump fluid from the concentrate container 15 to the draw-side input line 4b and provide the concentrate liquid to the draw-side 2b.

[0042] The draw-side output line 4c connects to the output port L of the draw-side 2b. out It is located between this point and the connection point P2 on the first dilution concentrate line 4e. Therefore, the draw-side output line 4c is connected to the outlet port L outThe first dilution concentrate line 4e is fluidly connected to the first dilution concentrate line 4d. The first dilution concentrate line 4e is located between the connector 40c, which is connected to the diluent container 16, and the concentrate line 4d. Thus, the first dilution concentrate line 4e fluidly connects the connector 40c, and therefore the diluent container 16, to the concentrate line 4d. A second pressure pump 32 is located to operate together with the draw-side output line 4c to provide pressure to the draw-side 2b. The first dilution concentrate valve 20e is connected to the first dilution concentrate line 4e between the connection point P2 of the draw-side output line 4c to the first dilution concentrate line 4e and the connection point of the first dilution concentrate line 4e to the concentrate line 4d. The main line 4f is located between the connection point P3 with the concentrate line path 4d and the outlet connector Po. Thus, the main line 4f fluidly connects the connection point P3 and the outlet connector Po. The second dilution concentrate line 4a is located between the connector 40d connected to the dilution container 16 and the connection point P3 with the main line 4f. The second dilution concentrate valve 20f is positioned to operate on the second dilution concentrate side input line 4a. Thus, the connection point P3 fluidly connects the main line 4f, the concentrate line 4d, the second dilution concentrate line 4a, and the draw side input line 4b. The draw flow path 4 further comprises several components located on the main line 4f, namely, a main valve 20g, a heating element 65, a temperature sensor 27, a main pump 23, a mixing chamber 24, a conductivity sensor 25, and an outlet valve 20j. The pure water line 4g is located between the connector 30c connected to the pure water container 17 and the main line 4f. Thus, the pure water line 4g fluidly connects the pure water container 17 and the main line 4f. The main valve 20g is positioned to operate on the main line 4f between point P3 and the connection point of the pure water line 4g to the main line 4f. The second concentrate line 4h is positioned between the second concentrate container 18 and the main line 4f. Thus, the second concentrate line 4h provides a fluid connection between the second concentrate container 18 and the main line 4f. The second concentrate pump 29 is positioned and configured to provide the flow of the second concentrate in the second concentrate line 4h.The main pump 23 is positioned and configured to provide flow to the main line 4f, downstream of the connection of the pure water line 4g to the main line 4f, and downstream of the connection of the second concentrate line 4h to the main line 4f. The temperature sensor 27 is positioned and configured to sense the temperature of the fluid in the main line 4f, upstream of the main pump 23, but downstream of the connection of the second concentrate line 4h to the main line 4f. The heating element 65 may heat the temperature of the generated fluid to a desired temperature sensed by the temperature sensor 27. The mixing chamber 24 is positioned downstream of the main pump 23 and upstream of the main conductivity sensor 25. An exhaust valve 20m is positioned to work with the exhaust line 4j connected between the mixing chamber 24 and the discharge line 3d. The exhaust line 4j transports excess gas in the mixing chamber 24 to the drain 31 so that the mixing chamber 24 can also function as a degassing chamber.

[0043] The apparatus 1 further comprises one or more characteristic sensors configured to sense one or more characteristics of the diluted dialysis concentrate and / or the dehydrated consumed dialysis fluid. One or more characteristic sensors are configured to sense, for example, one or more of the following: the concentration of the diluted dialysis concentrate, the concentration of the dehydrated consumed dialysis fluid, the weight of the diluted dialysis concentrate measured by a weighing scale, the weight of the dehydrated consumed dialysis fluid measured by a weighing scale, the flow rate of the diluted dialysis concentrate, and the flow rate of the dehydrated consumed dialysis fluid. The characteristic sensors may be, for example, concentration sensors, conductivity sensors, weighing scales, or flow sensors. The apparatus 1 comprises a conductivity sensor 11 connected to a first diluted concentrate line 4e between connection point P2 and connector 40c of the diluent container 16. The conductivity sensor 11 is configured to sense the concentration of the diluted dialysis concentrate, for example, its conductivity. The apparatus 1 also comprises a conductivity sensor 49 connected to a discharge line 3d to sense the concentration of the dehydrated consumed dialysis fluid, for example, its conductivity. In some embodiments, the conductivity sensor 49 is absent. In some embodiments, the apparatus 1 includes a weighing scale 48a positioned and configured to sense the weight of the diluted dialysate concentrate. In some embodiments, the apparatus 1 includes another weighing scale 48b positioned and configured to sense the weight of the dehydrated consumed dialysate. A first flow sensor 42a is positioned between the connection of the DC line 3c to the feed side input line 3a to sense the flow rate of the consumed dialysate in the feed side input line 3a, and therefore the flow rate of the fluid input to the feed side 2a. A second flow sensor 42b is positioned between the feed side 2a and the first pressure pump 7 to sense the flow rate of the dehydrated consumed dialysate in the discharge line 3d, and therefore the flow rate of the fluid output from the feed side 2a. In some embodiments, the apparatus 1 includes a third flow sensor 45 positioned and configured to sense the flow rate of the diluted concentrate solution output from the draw side 2b. The third flow sensor 45 is connected to the draw side output line 4c.

[0044] The apparatus 1 further comprises one or more pressure sensors configured to sense one or more pressures indicating the hydrostatic pressure difference between the draw side 2b and the feed side 2a. A pressure sensor 26 is connected to the feed side input line 3a to sense the pressure of the consumed dialysate in the feed side input line 3a. The sensed pressure represents the pressure at the feed side 2a. Another pressure sensor 46 is connected to the discharge line 3d between the feed side 2a and the first pressure pump 7 to sense the pressure of the dewatered consumed dialysate in the discharge line 3d. The sensed pressure represents the pressure at the feed side 2a. However, only one of the pressure sensors 26 or the other pressure sensor 46 is required to sense the pressure at the feed side 2a. A pressure sensor 47 is connected to the draw side output line 4c between the draw side 2b and the second pressure pump 32 to sense the pressure of the diluted dialysate concentrate in the draw side output line 4c, which represents the pressure at the draw side 2b. However, instead, this pressure sensor 47 may be connected to the draw-side input line 4b to sense the pressure on the draw-side 2b.

[0045] Any of the pumps described in this document may be positive displacement pumps (such as piston pumps) or non-positive displacement pumps (e.g., gear pumps) that operate on flow rate feedback from a flow sensor, for example. Non-positive displacement pumps are pumps that have a strong flow rate dependence on the hydrostatic pressure difference across the same pump and allow even small fluid flows relative to the direction of pump rotation. Thus, non-positive displacement pumps are pumps that can be controlled to allow a specific "leakage flow" in the direction opposite to the pumping direction (e.g., a low flow rate to the right of dewatered consumed dialysate while the pumping direction of the first pressure pump 7 is left in Figure 3). Any pump described in this document may be unidirectional or bidirectional. In addition to the feed pump 6 and the concentrate pump 10, the apparatus 1 also includes at least one pressure pump 7, 32. In the apparatus 1 of Figure 2 and the FO device apparatus of Figure 5, both the first pressure pump 7 and the second pressure pump 32 are present, but other configurations are possible, as described in Figures 3 and 4. Figures 3 to 5 illustrate various devices of one or more pressure pumps 7, 32 in combination with the FO unit 2. In all these devices, the feed pump 6 and concentrate pump 10 are present as shown in Figure 2 to provide the consumed dialysate flow and the dialysate concentrate flow, but for ease of explanation, they are described as being closer to the FO unit 2 than in Figure 1. In Figure 3, device 1 includes a first pressure pump 7 but does not include a second pressure pump 32. In one embodiment, the first pressure pump 7 in Figure 3 is a non-positive displacement pump controlled to increase the feed-side pressure. The flow delivery of a non-positive displacement pump depends on the pressure it pumps. This means that in order to reach a certain upstream (feed-side) pressure setpoint, the control device 50 can control the first pressure pump 7 to rotate in the direction and speed required to reach the setpoint. Therefore, depending on the desired feed-side pressure setpoint and the measured consumed dialysis flow rate, the control device 50 can control the first pressure pump 7 to operate at an appropriate speed in either the forward or reverse direction using feedback from the pressure sensor 46 or 26 in order to reach the desired pressure on the feed side 2a.In the example in Figure 3, a positive pump control signal to the first pressure pump 7 means rotation of the pump relative to the intended flow direction (the intended flow direction being out of the FO unit 2). In an alternative embodiment, the first pressure pump 7 in Figure 3 is a positive displacement pump. The positive displacement pump pumps only in the intended flow direction. By controlling the speed of the positive displacement pump using feedback from the pressure sensor 46, a desired feed-side pressure setpoint can be achieved and maintained on the feed side 2a. The advantage of this method is that the positive displacement pump prevents discharge backflow, and this pump can replace a single discharge valve. A possible disadvantage is that it introduces rigidity to the device, which may be undesirable in certain processes where an unconstrained feed-side outlet flow is desired.

[0046] In Figure 4, the apparatus 1 includes a second pressure pump 32 but does not include a first pressure pump 7. In one embodiment, the second pressure pump 32 in Figure 4 is a non-positive displacement pump configured to be adjusted to control the pressure on the draw side 2b. In an alternative embodiment, the second pressure pump 32 in Figure 4 is a positive displacement pump configured to be adjusted to control the pressure on the draw side 2b. Typically, the speed of the second pressure pump 32 is increased, thereby lowering the pressure on the draw side 2b to increase the hydrostatic pressure difference. By operating the second pressure pump 32 to pump the diluted dialysis concentrate from the FO unit 2 (in the intended flow direction) and controlling its speed using feedback from the pressure sensor 47 or 26, a desired pressure can be achieved and maintained on the draw side 2b.

[0047] Figure 5 illustrates the combination of the apparatus shown in Figures 3 and 4. The embodiment in Figure 5 also exists in apparatus 1 of Figure 2. In this case, both the first pressure pump 7 and the second pressure pump 32 may be operated to achieve the desired hydrostatic pressure difference.

[0048] Non-positive displacement pump is connected to outlet port E on feed side 2a. outIf acting on this, there may be a risk of discharge backflow to the feed side 2a of FO unit 2. When the FO session operating point changes (due to changes in the consumed dialysate flow and / or concentrate flow, or hydrostatic pressure difference), the water transport driving force from feed side 2a to draw side 2b increases and may exceed the rate at which water is supplied from the consumed dialysate flow. At this time, negative feed side pressure may occur, and fluid may be drawn out of the drain, which is undesirable. Below, we will explain that this is not a concern in steady operation but can be a concern when the operating point changes, and how this risk can be mitigated. When water extraction occurs from the consumed dialysate and water is transported to draw side 2b, the solute concentration in the consumed dialysate flow increases, which means that the osmotic driving force decreases. If an external hydrostatic pressure difference is applied to improve water transport, the solute concentration on feed side 2a increases further, and therefore the osmotic water transport driving force decreases even more. The (ideal) property of the FO membrane 2c is that only water should pass through the membrane, and no solute should pass through it. Here, the inlet port E of the feed side 2a in The solute flux in this case is independent of the water extraction rate from the consumed dialysate in the FO unit 2, and is determined by the outlet port E on the feed side 2a. out This needs to match the solute flux in the outlet port E of the feed side 2a. out This means that the volumetric flow rate will never be zero in a continuous water extraction process. If the hydrostatic pressure difference is increased to enhance water extraction, the solute concentration of the consumed dialysate will increase until the osmotic pressure and hydrostatic pressure difference are in equilibrium. At this point, the outlet port E outA positive flow rate of concentrated consumed dialysate still exists. Assuming steady-state operation, referring to Figure 5, the solute equilibrium across feed side 2a is Q1 × C1 = Q2 × C2 (where Q1 and C1 are the flow rate and conductivity of consumed dialysate, Q2 and C2 are the flow rate and conductivity of dehydrated consumed dialysate, Q3 and C3 are the flow rate and conductivity of diluted dialysate concentrate, and Q4 and C4 are the flow rate and conductivity of dialysate concentrate). The product of flow rate and solute concentration is constant across feed side 2a, which is the case for non-zero consumed dialysate solute concentrations at the outlet port E of feed side 2a. out This means that the flow velocity in the outlet is greater than zero. Discharge backflow is prevented by a check valve that prevents backflow and by using a second flow sensor 42b at the outlet port E on the feed side 2a. out Monitor the flow rate from and use scale 48b to access the outlet port E out The volume from the drain may be monitored and suppressed by using the compliance chamber 44 as described in Figure 6. The compliance chamber 44 is connected to the discharge line 3d to allow the dehydrated used dialysate to enter and exit the compliance chamber 44. The discharge valve 20i is closed during the FO operation so that the dehydrated used dialysate enters the compliance chamber 44 and gradually increases the pressure sensed by the pressure sensor 44a connected to the compliance chamber 44. Backflow from the drain is suppressed by opening the discharge valve 20i intermittently and for short periods to release the pressure to the drain. The opening of the discharge valve is controlled based on the sensed pressure (e.g., should be positive and have a certain magnitude) sensed by the pressure sensor 44a.

[0049] The dialysis concentrate in the concentrate container 15 contains an electrolyte solution. The electrolyte solution may contain at least one, for example, more of the following: NaCl, KCl, CaCl2, MgCl2, HAc, glucose, lactate, and bicarbonate. For example, the electrolyte solution may contain an electrolyte and a buffer, such as Na, Ca, Mg, and lactate. The dialysis concentrate in the second concentrate container 18 contains, for example, a glucose concentrate or an optoelectronic agent such as a modification of the concentrate in the concentrate container 15.

[0050] The control device 50 further comprises a control unit 30 including at least one memory and at least one processor. The control device 50 is configured to receive and / or collect measurement data or signals from sensors and other devices as described herein. In one embodiment, the control device 50 is configured to receive and / or collect measurements from conductivity sensors 11, 25, 49, measurements from pressure sensors 26, 28, 44a, 46, 47, flow rate measurements from flow velocity sensors 42a, 42b, and temperature from temperature sensor 27. The control device 50 is further configured to provide, for example, transmit control signals or data to pumps 6, 7, 10, 23, and 29 and / or valves in the valve device 20 in order to perform a number of different processes. The resulting parameters may be provided to the user by a user interface (not shown). Thus, the control device 50 may be configured to receive or collect any signals or data from components of the device 1 and to control the pumps and / or valves thereon. In some embodiments, the control device 50 is configured to control the apparatus 1 to perform a procedure or step of a procedure for diluting the dialysis concentrate and producing dialysate. At least one memory contains computer instructions for performing such a procedure or step of a procedure for diluting the dialysis concentrate and producing dialysate. When run on at least one processor, the control unit 30 controls one or more pumps 6, 7, 10, 23, and 29, and one or more valves of the valve apparatus 20 to perform one or more methods and procedures described herein.

[0051] Here, an example of a method for generating dialysate is described with reference to the flowchart in Figure 7. As discussed in this document, this method may be executed by the control device 50 in the apparatus 1 of Figure 1, or it may be stored as a computer program containing computer instructions in at least one memory location.

[0052] To generate dialysate, the method includes S1 providing a flow of dialysate concentrate to the draw side 2b of the forward osmosis (FO) unit 2. Providing S1 includes operating the concentrate pump 10 to pump dialysate concentrate from the concentrate container 15 to the draw side 2b, opening the concentrate valve 20d and the draw side input valve 20h, and closing the first dilution concentrate valve 20e, the second dilution concentrate valve 20f, and the main valve 20g. At this time, the dialysate concentrate is pumped from the concentrate container 15 to the concentrate line 4d and the draw side input line 4b, and to the feed side 2a. Simultaneously, the method of Figure 7 includes S2 providing a flow of consumed dialysate to the feed side 2a of the FO unit 2. Providing S2 includes operating the feed pump 6 to pump consumed dialysate from the consumed dialysate container 19 or from another source of consumed dialysate connected at connection point Pi. In one embodiment, the method shown in Figure 7 includes operating the feed pump 6 (forward), opening the input valve 20a and the DC line valve 20s, and closing the container valve 20p and the feed-side input line valve 20b. At this time, the consumed dialysate is pumped from the inlet connector Pi to the feed side 2a via the feed-side input line 3a, the container line 3b, the DC line 3c, and again via the feed-side input line 3a. In another embodiment, the method shown in Figure 7 includes operating the feed pump 6 (reverse), opening the container valve 20p and the feed-side input line valve 20b, and closing the input valve 20a and the DC line valve 20s. At this time, the consumed dialysate is pumped from the consumed dialysate container 19 to the feed side 2a via the container line 3b and the feed-side input line 3a.

[0053] Water is transported from the consumed dialysate through the FO membrane 2c of the FO unit 2 to the dialysate concentrate via the osmotic pressure difference between the draw side 2b and the feed side 2a, thereby diluting the dialysate concentrate into a diluted dialysate concentrate and dehydrating the consumed dialysate into dehydrated consumed dialysate. The diluted dialysate concentrate is output from the draw side 2b to the draw side output line 4c. The second pressure pump 32 operates to allow the diluted dialysate concentrate to reach the diluent container 16 while the first diluted concentrate valve 20e is closed. At this time, the diluted dialysate concentrate is pumped by the concentrate pump 10 from the draw side 2b to the draw side output line 4c and to the diluent container 16 via the first diluted concentrate line 4e. The dehydrated consumed dialysate is output from the feed side 2a to the discharge line 3d. The first pressure pump 7 operates to allow the dehydrated, consumed dialysate to reach the drain 31 while the discharge valve 20i is open. The exhaust valve 20m and the drain connection valve 20k are closed, if present. Thus, the dehydrated, consumed dialysate is pumped by the feed pump 6 from the feed side 2a to the discharge line 3d and further to the drain 31. Water transport rate Q across the FO membrane 2c w The osmotic pressure difference ΔP between the feed side 2a and the draw side 2b is osm and the hydrostatic pressure difference ΔP hyd It depends on the sum of the two. If the hydrostatic pressure difference is zero, then ΔP osm is Q w It is the sole driving force. Therefore, Q is given by the characteristics of the FO membrane 2c, the consumed dialysate flow rate, the concentrate flow rate, the composition of the consumed dialysate, and the composition of the concentrate. w There exists a theoretical maximum value for Q. When the process runs very slowly, it approaches the theoretical maximum value, and as a result, Q w This makes it possible to equilibrium the osmotic pressure difference between the feed side 2a and the draw side 2b, ΔP osm ΔP approaches zero. hyd Water extraction Q w If used to improve the extraction rate, the extraction rate can be increased beyond the theoretical maximum value mentioned above. wTo increase ΔP, the method may also include providing a hydrostatic pressure difference between the draw side 2b and the feed side 2a using one or more pressure pumps 7, 32 S3. Thus, while the consumed dialysate is supplied to the feed side 2a and the concentrated liquid 2b is supplied to the draw side 2b, the first pressure pump 7, the second pressure pump 32, or both operate to provide a specific hydrostatic pressure difference between side 2a and side 2b. This can increase the water extraction rate. The hydrostatic pressure difference is such that the pressure on the feed side 2a is greater than the pressure on the draw side 2b. The hydrostatic pressure on the draw side 2b can be atmospheric pressure or near atmospheric pressure (except for the potential height difference between the draw side 2b and the diluent container 16) when connected to the diluent container 16. Thus, ΔP hyd This may be determined from the measured hydrostatic pressure at the feed side 2a. Alternatively, the hydrostatic pressure at the draw side 2b may also be measured, and ΔP hyd The hydrostatic pressure P at the feed side 2a is hyd_feed From the draw side 2b, the hydrostatic pressure P hyd_draw It is determined by subtracting (ΔP hyd =P hyd_feed -P hyd_draw ).

[0054] The method in Figure 7 further includes sensing one or more properties of the diluted dialysis concentrate and / or the dehydrated consumed dialysis fluid S4. Sensing S4 is performed using one or more of the property sensors as described above. The properties may be, for example, the concentration of the diluted dialysis concentrate, the concentration of the dehydrated consumed dialysis fluid, the weight of the diluted dialysis concentrate measured by a weighing scale, the weight of the dehydrated consumed dialysis fluid measured by a weighing scale, the flow rate of the diluted dialysis concentrate, or the flow rate of the dehydrated consumed dialysis fluid.

[0055] The method in Figure 7 further includes sensing one or more pressures indicating a hydrostatic pressure difference between the draw side 2b and the feed side 2a (S5). Sensing S5 is performed by sensing using one or more of the pressure sensors 26, 28, and 46. Pressure measurement may be given directly by calculating the pressure difference, for example, by calculating the difference between the pressure at the feed side 2a and the pressure at the draw side 2b, if one of the sides, typically the draw side 2b, is fluidly connected to atmospheric pressure, in which case the pressure at the draw side 2b is equal to atmospheric pressure.

[0056] The method in Figure 7 includes controlling at least one of the following to produce a diluted dialysis concentrate: the flow rate of the consumed dialysate to the feed side 2a, the flow rate of the dialysis concentrate to the draw side 2b, and the hydrostatic pressure difference, based on one or more properties of the diluted dialysis concentrate and / or the dehydrated consumed dialysate and one or more sensed pressures indicating a hydrostatic pressure difference. Controlling the dilution rate, and therefore the dilution of the dialysis concentrate, is controlled based on one or more properties of the fluid and the hydrostatic pressure difference. Controlling the dilution may also include controlling the composition of the diluted dialysis concentrate. Controlling S6 may also include controlling the FO process so that a target dilution factor of the diluted dialysis concentrate is achieved. In this document, the dilution ratio is expressed according to the number of units of sample per total number of units (S:T; total number of samples + number of units of diluent). Thus, a dilution ratio of 1:5 means having 1 unit of concentrate and 4 units of water to give a total of 5 units of diluted concentrate. For example, a target dilution ratio of 1:20 means achieving 10 liters of diluted dialysis concentrate for every 500 ml of dialysis concentrate, which also means that 9.5 liters of water are extracted from the consumed dialysis fluid. To calculate the target dilution factor (= final volume of diluted concentrate / initial volume of concentrate), 10 liters of diluted dialysis concentrate is divided by 500 ml of dialysis concentrate to obtain a dilution factor of 20. Control S6 may also include reaching a target dilution factor corresponding to a specific composition of the dialysis fluid (before mixing with any subsequent concentrate to provide the final dialysis fluid), and / or reaching a target dilution factor that matches further dilution with a limited amount of available water to provide a specific composition of the dialysis fluid.

[0057] The hydrostatic pressure difference may be controlled based on feedback from various sensors. In some embodiments, control S6 includes controlling the hydrostatic pressure difference using one or more pressure pumps 7,32 based on one or more properties of the diluted dialysis concentrate and / or dehydrated consumed dialysate and one or more sensed pressures indicating the hydrostatic pressure difference. The one or more pressure pumps 7,32 to be controlled may use conductivity feedback. Thus, the one or more pressure pumps 7,32 may be controlled to cause a hydrostatic pressure difference that maintains the conductivity (and therefore the dilution coefficient) at a specific level, for example, a target conductivity of the diluted concentrate solution being produced. This target conductivity typically corresponds to a desired dilution ratio or coefficient, and is therefore the desired dilution ratio of the dialysis concentrate according to C1·V1=C2·V2, where C1 is the concentration of the dialysis concentrate, V1 is the volume of the added dialysis concentrate, C2 is the final concentration of the diluted concentrate solution, and V2 is the final volume of the diluted dialysis concentrate solution. Here, the concentration may be determined as a function of conductivity and dilution coefficient, and the volume may be determined as a function of flow velocity. Controlling one or more pressure pumps 7, 32 with non-pressure feedback means that the hydrostatic pressure difference is indirectly controlled, since it is a parameter that controls the water extraction rate. When a non-pressure feedback mechanism is used, the hydrostatic pressure difference must also be monitored, and measures must be taken to avoid excessive pressure, such as adjusting or controlling the operating point (consumed dialysate flow rate and / or concentrate flow rate) before the hydrostatic pressure difference becomes too high. It may also include changing the control method so that the hydrostatic pressure difference is maintained at its maximum allowable hydrostatic pressure difference, and it is acceptable that the conductivity (and therefore the dilution coefficient) differs from the target.

[0058] The flow rate of consumed dialysate is typically determined by the available volume for the FO process before the dialysate is ready for use. However, in some embodiments, the flow rate can deviate from the flow rate thus determined. For example, the flow rate may be reduced to increase the overall water extraction efficiency, provided that there is sufficient consumed dialysate in container 19 and the consumed dialysate remaining after the FO session can be used in a later stage (e.g., during the next retention period).

[0059] The flow rate of the concentrate solution is determined by the time available in the FO process before the dialysate is prepared and the amount of concentrate required to produce the next batch of dialysate. This is true over time, and for example, if a certain amount of diluted concentrate solution is already available in the diluent container 16, the amount of concentrate to be flowed may be reduced from the required long-term average to improve water extraction efficiency.

[0060] In PD, over time, the ratio between the consumed dialysate flow rate and the concentrated liquid flow rate is a function of the target dilution factor and the discharge-to-fill ratio (EFR). EFR accounts for all additions and subtractions of fluid that make the available consumed dialysate volume for water extraction different from the filled volume (e.g., ultrafiltration volume (UF volume) and lost / added discharge volume), and is calculated as (total available consumed dialysate from treatment) / (treatment filled volume). For example, if a total of 12 L of fluid is filled and 13 L is discharged during treatment, then 1 L of UF volume is drawn, and thus EFR = 13 / 12 = 1.083, which, using the desired dilution factor (dilFactor) of 20, gives a flow ratio = 1.083 × dilFactor = 1.083 × 20 = 21.67. Thus, if the concentrate flow rate is 1 ml / min, the consumed dialysate flow rate is 21.67 ml / min. A higher EFR results in more consumed dialysate, which increases water extraction performance.

[0061] The available volume of consumed dialysate may be predetermined to be the volume that is always known to be available. Alternatively, the available volume may be measured by weighing or determined by the volume pumped by the feed pump 6 into the consumed dialysate container 19. In PD, the drain during treatment may provide up to 15 liters of consumed dialysate in total. The available time may be limited by the time from when the consumed dialysate becomes available until the diluted dialysate concentrate is ready for use. For PD patients using cyclas for APD, the patient may be drained during the course of treatment and at the end of the early morning (even if the patient has been given the last fill for the day), after which a new treatment is started at bedtime. In such an example, the available time to generate the diluted concentrate / dialysis fluid is 12-15 hours. Thus, 15 liters of consumed dialysate and 12 hours of available time give the feed pump 6 a minimum possible flow rate of 15,000 ml / (12 × 60) = 20.8 ml / min, assuming all of the consumed dialysate is used. Production / FO sessions may also be performed during stagnation and with smaller amounts of fluid and shorter available time for production / FO sessions. In other words, in some embodiments, control S6 includes controlling the flow rate of consumed dialysate to the feed side 2a based on the available volume of consumed dialysate and the length of time available to produce the desired amount of diluted concentrate, in order to provide a desired amount of diluted concentrate at the end of the period. In some embodiments, the flow rate of consumed dialysate supplied by the feed pump 6 is in the range of 15 to 50 ml / min. In some embodiments, the flow rate of dehydrated consumed dialysate is in the range of 1 to 10 ml / min. Thus, the flow rate controlled by the first pressure pump 7 is very low, 1 to 10 ml / min or less. Here, the first pressure pump 7 may be configured to provide a pressure of at least 4 bar to the feed side 2a by controlling such low flow rates.

[0062] Dialysis concentrate is typically 20 times more concentrated than readily available dialysate. The concentrate container 15 contains, for example, 2 liters of dialysate concentrate. If the amount required for one treatment is 500 ml and the available time is 12 hours, the minimum possible flow rate for the concentrate pump 10 would be 500 ml / (12 × 60) = 0.7 ml / min. In other words, in some embodiments, control S6 involves controlling the flow rate of the dialysate concentrate 15 to the draw side 2b based on the volume of dialysate concentrate required to produce a desired amount of diluted concentrate and the length of the period, in order to provide a desired amount of diluted concentrate at the end of the period.

[0063] The following text describes several different control alternatives that combine flow rate control and hydrostatic pressure difference control. In the first alternative, the hydrostatic pressure difference is controlled to a predetermined pressure, e.g., the maximum allowable hydrostatic pressure difference, and the flow rates of consumed dialysate and concentrate are controlled to achieve a desired target conductivity of the diluted concentrate. In the second alternative, the flow rates of consumed dialysate and concentrate are controlled to achieve a desired volume of diluted concentrate based on the available amount of consumed dialysate, and the hydrostatic pressure difference is controlled, e.g., to achieve a desired target conductivity of the diluted concentrate. In the third alternative, both the flow rates of consumed dialysate and concentrate and the hydrostatic pressure difference are controlled to achieve a desired target conductivity of the diluted concentrate.

[0064] In the first alternative, the method in Figure 7 includes controlling the hydrostatic pressure difference using one or more pressure pumps 7, 32 based on one or more sensed pressures to achieve a predetermined hydrostatic pressure difference S6. The hydrostatic pressure difference may be controlled in multiple ways. Generally, to increase the water extraction rate, the hydrostatic pressure difference should be positive from the feed side 2a to the draw side 2b, meaning that the feed side pressure is greater on the feed side 2a than on the draw side 2b. Thus, the water extraction rate can be increased by increasing the feed side pressure and / or decreasing the draw side pressure. In one embodiment, controlling S6 includes increasing the pressure on the feed side 2a using a first pressure pump 7, which is a non-positive displacement pump configured to rotate in and / or against the intended flow direction. Figure 3, for example, may use a non-positive displacement pump as the first pressure pump 7. In another embodiment, control S6 includes increasing the pressure on the feed side 2a using a first pressure pump 7, which is a positive displacement pump configured to rotate only in the intended flow direction. For example, Figure 3 may use a positive displacement pump as the first pressure pump 7. In another embodiment, control S6 includes decreasing the pressure on the draw side 2b using a second pressure pump 32, which is a positive displacement or non-positive displacement pump configured to rotate in the intended flow direction. The predetermined hydrostatic pressure difference is, for example, the maximum allowable hydrostatic pressure difference. The maximum allowable hydrostatic pressure difference is typically determined by the membrane manufacturer, for example, 4 bar, more commonly 1 to 10 bar. The maximum allowable hydrostatic pressure difference may be distributed asymmetrically between the feed side 2a and the draw side 2b. The flow rates of the dialysate concentrate and consumed dialysate may be configured to predetermined values ​​based, for example, the known amount of available fluid and the time available for production. Preferably, the flow rate is controlled to maximize osmotic water exchange within a given time frame, the available volume of consumed dialysate, and the required volume of concentrate. Based on these volumes and a given time frame, the smallest possible flow rate can be calculated to provide the most efficient FO process within the time frame. In this first alternative, the dilution factor of the dialysate concentrate is not controlled.Instead, the coefficient is made as large as possible based on a predetermined flow rate and maximum hydrostatic pressure difference. This first alternative is interesting, for example, if the target dilution coefficient cannot be reached due to high discharge osmolality, insufficient consumed dialysate, or a small FO membrane surface area.

[0065] In the second alternative, sufficient volumes of consumed dialysate and concentrate are available to obtain a desired volume of diluted concentrate. In this case, control S6 includes configuring the flow rate to achieve a target dilution coefficient that nominally gives the desired volume of diluted concentrate, given known dilution ratios for the concentrations of the fluids (consumed dialysate and concentrate) and the flow rates (of the consumed dialysate and concentrate). Thus, the flow rate is configured to a constant value and is not changed unless the hydrostatic pressure difference exceeds a maximum level. In such cases, one or both of the flow rates may be reduced. The concentration of the fluid may be known in advance or determined by conductivity measurement. In addition to flow control, control S6 includes controlling the hydrostatic pressure difference using one or more pressure pumps 7, 32 to equalize the properties of the diluted dialysate concentrate and / or dehydrated consumed dialysate to target values ​​of the properties. For example, a conductivity sensor may sense the conductivity of the diluted dialysate concentrate. The conductivity of the diluted dialysate concentrate may have a known relationship with the dilution coefficient of the diluted dialysate concentrate. Therefore, the target dilution factor may correspond to a predetermined conductivity of the diluted dialysis concentrate. Thus, the hydrostatic pressure difference may be controlled to achieve a predetermined conductivity of the diluted dialysis concentrate corresponding to the target dilution factor. For example, if the conductivity is too high, the dilution factor is too low, and the hydrostatic pressure difference is increased. If the conductivity is too low, the dilution factor is too high, and the hydrostatic pressure difference is decreased. Hydrostatic pressure control thereby eliminates any errors from flow control caused, for example, by different conductivity of the fluid.

[0066] If the concentrations of the consumed dialysate and dialysate concentrate are known, the same reasoning applies to the conductivity of the dehydrated consumed dialysate. In some embodiments, other characteristics such as weight and flow rate are used. For example, control S6 may include using a predetermined target dilution factor and the flow rate of the dialysate concentrate provided by the concentrate pump 10 in order to calculate the expected flow rate of the diluted dialysate concentrate to achieve the target dilution factor. Control S6 may further include controlling the hydrostatic pressure difference so that the flow rate of the diluted dialysate concentrate is at the expected rate so that the target dilution ratio is achieved.

[0067] In the third alternative, the concentrate pump 10 and the second pressure pump 32 are controlled to achieve a dilution coefficient equal to the target dilution coefficient. Control S6 includes controlling the flow rate of the dialysis concentrate using the concentrate pump 10 and controlling the flow rate of the dialysis concentrate using the second pressure pump 32 of one or more pressure pumps 7, 32, such that the flow rate of the dialysis concentrate is equal to the inlet flow rate of the dialysis concentrate to the draw side 2b multiplied by the target dilution coefficient. Thus, the concentrate pump 10 and the second pressure pump 32 are controlled to force a dilution equal to the target dilution coefficient. To do this, the second pressure pump 32 pumps the dialysis concentrate at a flow rate equal to the flow rate of the dialysis concentrate pumped by the concentrate pump 10 multiplied by the target dilution coefficient. Therefore, the flow rate of the dialysis concentrate is greater than the flow rate of the dialysis concentrate by a target dilution coefficient multiple. In some embodiments, control S6 includes fine-tuning the dilution coefficient by controlling the ratio between the concentrate pump 10 and the second pressure pump 32 to equalize the properties of the diluted dialysis concentrate to a target value of the properties. Such fine-tuning is performed, for example, using conductivity feedback. For example, control S6 is performed at the outlet port L of the draw side 2b out The flow rate from the inlet port L of draw side 2b in This may include controlling the second pressure pump 32 so that the flow rate to the outlet port L on the draw side 2b is multiplied by the target dilution factor. outThe flow rate from the inlet port L of draw side 2b in When the flow rate to the second pressure pump 32 is multiplied by the target dilution factor, the resulting pump ratio, and therefore the pump ratio between the second pressure pump 32 and the concentrate pump 10, may be locked. This pump ratio may then be fine-tuned, for example, by measuring the conductivity of the diluted dialysis concentrate, to eliminate errors between the target diluted dialysis concentrate conductivity and the measured diluted dialysis concentrate conductivity, or between the predicted diluted dialysis concentrate conductivity and the measured diluted dialysis concentrate conductivity. The resulting hydrostatic pressure difference may be what is needed to extract enough water to operate the pumps. However, the resulting hydrostatic pressure difference is monitored so as not to exceed the maximum allowable hydrostatic pressure difference. If it is exceeded, the consumed dialysate flow rate and / or concentrate flow rate are controlled so that the hydrostatic pressure difference is reduced to an allowable value, for example, below the maximum allowable hydrostatic pressure difference. Excessive negative pressure on the draw side 2b should be avoided. For example, the pressures on both sides 2a and 2b may be measured, and the draw-side pressure from the feed side 2a may be controlled by controlling the first pressure pump 7. In this embodiment, the pump may be positive displacement or non-positive displacement with flow rate feedback control. In other words, in some embodiments, controlling S6 includes controlling the flow rate of consumed dialysate to the feed side 2a and / or the flow rate of dialysate concentrate 15 to the draw-side 2b, based on one or more sensed pressures indicating a hydrostatic pressure difference, such that the hydrostatic pressure difference is kept below the maximum allowable hydrostatic pressure difference. It should be understood that the target dilution factor of the dialysate concentrate is not typically the same as the final (nominal) dialysate concentrate dilution factor (or corresponding ratio) in the final mixed dialysate. Therefore, the final dialysate concentrate dilution factor should be achieved in the final dialysate after the addition of other concentrates, e.g., glucose concentrate for PD, which means that the target dialysate concentrate dilution factor in the FO process will be lower than the final dialysate concentrate dilution factor and will also depend on the target concentrations for other concentrates in the final dialysate. For example, with respect to PD, the dilution factor of the final dialysis concentrate may depend on the target glucose concentration in the final dialysate.

[0068] After the diluted concentrate is collected in the diluent container 16, the diluted concentrate may be pumped using the concentrate pump 10 to open the first diluted concentrate valve 20e and the second diluted concentrate valve 20f, and close the draw-side input valve 20h, concentrate valve 20d and main valve 20g, thereby circulating within the first diluted concentrate line 4e, a portion of the concentrate line 4d, the second diluted concentrate line 4a and the diluent container 16. The conductivity sensor 11 measures the conductivity of the circulating diluted concentrate to monitor whether the conductivity is stable and therefore the diluted concentrate is homogeneous.

[0069] To mix the dialysate, the diluted concentrate solution in the diluent container 16 is pumped into the main line 4f by operating the concentrate pump 10, which opens the first diluent concentrate valve 20e, the main valve 20g, and the outlet valve 20j, and closes the concentrate valve 20d, the draw-side input valve 20h, the second diluent concentrate valve 20f, and the drain connection valve 20k. Simultaneously, a second concentrate solution from a second concentrate container 18, such as glucose, is passed through the main line 4f by operating the second concentrate pump 29. In some embodiments, another concentrate solution from another concentrate container (not shown) is passed through the main line 4f and connected to a line (not shown) between the other concentrate container and the main line 4f. In other words, the method of Figure 7 may include controlling the flow rate of the second or third concentrate from the concentrate container 18 so that it flows into the diluent concentrate solution to form the dialysate. Pure water flows from the pure water container 17 into the main line 4f. The main pump 23 supplies the desired flow rate of the resulting dialysate to the main line 4f downstream of the main pump 23. A conductivity sensor 25 measures the conductivity of the resulting dialysate from the main pump 23. The concentrate pump 10 is controlled to a specific speed to achieve a desired predetermined concentration of the resulting dialysate, based on the conductivity of the generated fluid, the conductivity of the diluted concentrate solution, and the flow rate of the generated fluid. The second concentrate pump 29 is controlled to a specific speed based on the flow rate of the generated fluid to achieve a specific composition of concentrate in the generated fluid. In the mixing chamber 24, the diluted concentrate solution, the second concentrate solution, and pure water are mixed to produce dialysate. The mixing chamber 24 may be small and contain only 30-100 ml of fluid. The dialysate is then delivered to the desired destination (e.g., a storage container or dialysis machine, or a catheter connected to a PD patient) at the outlet connector Po. The level sensing device 66 monitors the level in the mixing chamber 24, and if the level is too low, the exhaust valve 20m, which allows gas to pass through the drain, is opened to raise the level. The main conductivity sensor 25 measures the conductivity of the final dialysate. If the conductivity is not within a predetermined limit, the dialysate is passed through the drain 31 via the drain connection line 4i. The drain connection line 4i is connected to the drain connection valve 20k, which opens when the dialysate is passed through the drain 31.A pressure sensor 28 is connected to the main line 4f downstream of the output valve 20j to sense the pressure at the outlet connector Po.

[0070] Figure 8 illustrates the results of tests using a non-positive displacement pump to increase the feed-side pressure described above, using the apparatus in Figure 2 and the FO apparatus in Figure 3. The tests are performed using a feed-side fluid consisting of a PD electrolyte concentrate nominally diluted 1:20 and containing 0.5% glucose. The flow rate of the feed solution is 44 ml / min. The draw solution is a PD electrolyte concentrate solution, with a flow rate of 2 ml / min. The operating point corresponds to the expected value with a nominal mixing dilution factor of 20 for the concentrate, and 1 liter of UF draw per APD treatment. The top pane shows the pump control signal to the first pressure pump 7, and the second pane from the top shows the desired feed-side pressure. The feed-side pressure setpoint is increased in steps, while the control unit 30 responds by increasing the pump speed acting against the intended flow direction at the feed-side outlet (top pane). As seen in the second pane from the top, the actual feed-side pressure follows the setpoint, demonstrating good controllability of the feed-side pressure by this method. The third pane from the top and the bottom pane illustrate how water-saving performance depends on the feed-side pressure (closely related to the total hydrostatic pressure difference). The third pane from the top shows the additional amount of pure water required to mix 1 liter of PD dialysate (mixing from concentrate typically requires 900-950 ml of water per liter of dialysate). The bottom pane shows the percentage reduction in pure water demand compared to dialysate mixing from PD concentrate and water. Negative pure water demand or a reduction of more than 100% in pure water demand indicates net pure water generation. However, it should be noted that such net water generation is desirable at a stable "good" operating point in order to achieve sufficient overall water extraction efficiency, given process edge effects, potential under-discharge, and the possibility that certain procedures may temporarily reduce water extraction efficiency.

[0071] This disclosure relates to a technology for producing or generating dialysate (therapeutic fluid) for a dialysis system. This technology is applicable to both peritoneal dialysis (PD) therapy and extracorporeal (EC) hematotherapy. Simply put, fluid generation related to PD therapy and EC hematotherapy will be briefly discussed with reference to Figures 9A and 9B.

[0072] Figure 9A is a general schematic of a dialysis system for PD treatment. The dialysis system comprises a therapy system 90 fluidly connected to the peritoneal cavity PC of patient P. As indicated by double-ended arrows, the therapy system 90 is operable to transport unused therapy fluid into the peritoneal cavity PC and to receive consumed therapy fluid from the peritoneal cavity on a fluid pathway 91. The fluid pathway 91 may be defined by a tube connected to an implanted catheter (not shown) that fluidly communicates with the peritoneal cavity PC. The therapy system 90 may be configured for any type of PD therapy. In one example, the therapy system 90 comprises one or more containers that are manually handled to perform CAPD. In another example, the therapy system 90 comprises a dialysis machine ("cycla") that performs automated dialysis therapy. The dialysis system further comprises a device 1 for generating dialysate, as described according to any embodiment of this document, and configured to generate fluid for use by the therapy system 90. The therapy fluid is supplied from the device 1 to the therapy system 90 on a fluid pathway 92. The consumed dialysate may be handled by the therapy system 90 or transferred for handling by the device 1. The fluid path 92 may include two separate fluid lines or one fluid line for bidirectional flow. The fluid path 92 is connected to an inlet connector Pi and an outlet connector Po (Figure 2). The consumed dialysate may be stored, regenerated, sent to a drain, or any combination thereof. In some embodiments, all consumed dialysate is sent to the device 1 for use in the FO process.

[0073] Figure 9A is a general schematic of a dialysis system for EC hemotherapy. The dialysis system comprises a therapy system 90 which is fluidly connected to the patient P's vascular system via a fluid pathway. In the example described, the fluid pathway is defined by a tube 91A for blood withdrawal and a tube 91B for blood return. As indicated by the arrows, the therapy system 90 is operable to draw blood from patient P through tube 91A, process the blood, and return the processed blood to the patient through tube 91B. Tubes 91A and 91B are connected to an access device (e.g., catheter, graph, or fistula, not shown) which is fluidly connected to the patient P's vascular system. The therapy system 90 may be configured to process blood by any form of EC hemotherapy, such as HD, HF, or HDF, on which dialysate is consumed. Dialysis is supplied from device 1 to the therapy system 90 via a fluid pathway 92. Consumed therapy fluid may be handled by the therapy system 90 or transferred for handling by device 1. The fluid path 92 may include two separate fluid lines or one fluid line for bidirectional flow. The fluid path 92 is connected to an inlet connector Pi and an outlet connector Po (Figure 2). The consumed treatment fluid may be stored, regenerated, delivered to a drain, or any combination thereof.

[0074] Apparatus 1 may include certain embodiments that are described below and can be used to carry out the methods described herein.

[0075] In some embodiments, the control device 50 is configured to control the flow rate of consumed dialysate to the feed side 2a based on the available volume of consumed dialysate and the length of the period available to produce a desired amount of diluted concentrate, and to control the flow rate of dialysate concentrate 15 to the draw side 2b based on the volume of dialysate concentrate required to produce a desired amount of diluted concentrate and the length of the period available to provide a desired amount of diluted concentrate at the end of the period.

[0076] In some embodiments, the control device 50 is configured to control the hydrostatic pressure difference using a second pressure pump 32 of one or more pressure pumps 7, 32, based on one or more characteristics of the diluted dialysis concentrate and / or dehydrated consumed dialysate and one or more sensed pressures indicating the hydrostatic pressure difference.

[0077] In some embodiments, the control device 50 is configured to control the hydrostatic pressure difference using a second pressure pump 32 based on one or more sensed pressures in order to achieve a predetermined hydrostatic pressure difference. In some embodiments, the predetermined hydrostatic pressure difference is the maximum allowable hydrostatic pressure difference.

[0078] In some embodiments, the control device 50 is configured to control the hydrostatic pressure difference to equalize the characteristics of the diluted dialysis concentrate and / or the dehydrated consumed dialysate, based on the characteristics of the characteristics of the characteristics.

[0079] In some embodiments, the control device 50 is configured to control the flow rate of the diluted dialysis concentrate using the concentrate pump 10 and to control the flow rate of the diluted dialysis concentrate using one or more pressure pumps 7, 32, such that the flow rate of the diluted dialysis concentrate is equal to the value obtained by multiplying the inlet flow rate of the dialysis concentrate to the draw side 2b by a target dilution factor.

[0080] In some embodiments, the control device 50 is configured to control the ratio between the concentrate pump 10 and one or more pressure pumps 7, 32 in order to make the characteristics of the diluted dialysis concentrate equal to a target value of the characteristics, based on the characteristics of the diluted dialysis concentrate.

[0081] In some embodiments, the control device 50 is configured to control the flow rate of consumed dialysate to the feed side 2a and / or the flow rate of dialysate concentrate 15 to the draw side 2b, based on one or more sensed pressures indicating the hydrostatic pressure difference, such that the hydrostatic pressure difference is kept below the maximum allowable hydrostatic pressure difference.

[0082] In some embodiments, one or more pressure pumps 7, 32 include a pressure pump 7 configured to operate on the consumed dialysate output from the feed side 2a.

[0083] In some embodiments, the pressure pump 7 is configured to pump in both the upstream and downstream directions.

[0084] In some embodiments, one or more pressure pumps 7, 32 include a pressure pump 32 configured to operate on the dilution dialysate output from the draw side 2b.

[0085] In some embodiments, the control device 50 is configured to control the flow rate of a second or third concentrate so that it flows into the diluted concentrate solution to form a dialysate.

[0086] In some embodiments, the apparatus 1 is configured to supply pure water to a diluted concentrate to form a dialysate.

[0087] Although the present invention has been described in relation to what is currently considered to be the most practical and preferred embodiment, it should be understood that the present invention is not limited to the disclosed embodiment, but rather is intended to encompass the spirit of the appended claims and equivalents, and the various variations and equivalent configurations contained therein.

Claims

1. A device (1) for generating dialysate, wherein the device (1) is A draw fluid path (4) including one or more concentrate connectors (30a, 30b), wherein each connector is configured to be connected to a dialysis concentrate supply source (15, 18), A feed fluid path (3) includes a connector (Pi, 40a) configured to be connected to a source of consumed dialysate, A forward osmosis (FO) unit (2) comprising a feed side (2a) and a draw side (2b) separated by an FO membrane (2c), wherein the feed side (2a) is included in the feed fluid pathway (3), the draw side (2b) is included in the draw fluid pathway (4), and the FO unit (2) is configured to receive dialysis concentrate on the draw side (2b) and the consumed dialysis fluid on the feed side (2a), and water is transported from the consumed dialysis fluid to the dialysis concentrate through the FO membrane (2c) via the osmotic pressure difference between the draw side (2b) and the feed side (2a), thereby diluting the dialysis concentrate to a diluted dialysis concentrate and dehydrating the consumed dialysis fluid to a dehydrated consumed dialysis fluid. One or more characteristic sensors configured to sense one or more characteristics of the diluted dialysis concentrate and / or the dehydrated consumed dialysis fluid, One or more pressure sensors configured to sense one or more pressures indicating a hydrostatic pressure difference between the draw side (2b) and the feed side (2a), A control device (50), To ensure that the flow of the dialysis concentrate solution is provided to the draw side (2b), To ensure that the flow of the consumed dialysate is provided to the feed side (2a), One or more pressure pumps (7, 32) are used to provide a hydrostatic pressure difference between the draw side (2b) and the feed side (2a), The flow rate of the consumed dialysate to the feed side (2a) and The flow rate of the dialysis concentrate to the draw side (2b) and At least one of the above-mentioned hydrostatic pressure difference and, Apparatus (1) comprising: a control device (50) configured to control the production of the diluted dialysis concentrate based on one or more characteristics of the diluted dialysis concentrate and / or the dehydrated consumed dialysis fluid and one or more sensed pressures indicating the hydrostatic pressure difference.

2. The apparatus (1) according to claim 1, wherein the control device (50) is The flow rate of consumed dialysate to the feed side (2a) is controlled based on the available volume of consumed dialysate and the length of time available to generate a desired amount of the diluted dialysate concentrate. Apparatus (1) is further configured to control the flow rate of the dialysis concentrate to the draw side (2b) based on the volume of dialysis concentrate required to produce the desired amount of diluted dialysis concentrate and the length of the period, in order to provide the desired amount of diluted dialysis concentrate at the end of the period.

3. The apparatus (1) according to claim 1, wherein the control device (50) is further configured to control the hydrostatic pressure difference using one or more pressure pumps (7, 32) based on one or more characteristics of the diluted dialysis concentrate and / or dehydrated consumed dialysis fluid and one or more sensed pressures indicating the hydrostatic pressure difference.

4. The apparatus (1) according to claim 3, wherein the control device (50) is further configured to control the hydrostatic pressure difference using one or more pressure pumps (7, 32) based on one or more sensed pressures in order to achieve a predetermined hydrostatic pressure difference.

5. The apparatus (1) according to claim 4, wherein the predetermined hydrostatic pressure difference is the maximum allowable hydrostatic pressure difference.

6. The apparatus (1) according to claim 3, wherein the control device (50) is further configured to control the hydrostatic pressure difference based on the characteristics of the diluted dialysis concentrate and / or dehydrated consumed dialysis fluid, so as to make the characteristics equal to a target value of the characteristics.

7. The apparatus (1) according to claim 2, wherein the control device (50) is further configured to control the flow rate of the diluted dialysis concentrate using a concentrate pump (10) such that the flow rate of the diluted dialysis concentrate is equal to the value obtained by multiplying the inlet flow rate of the dialysis concentrate to the draw side (2b) by a target dilution coefficient, and to control the flow rate of the diluted dialysis concentrate using a second pressure pump (32) of the one or more pressure pumps (7, 32).

8. The apparatus (1) according to claim 7, wherein the control device (50) is further configured to control the ratio between the concentrate pump (10) and the second pressure pump (32) based on the characteristics of the diluted dialysis concentrate solution, in order to make the characteristics equal to a target value of the characteristics.

9. The apparatus (1) according to claim 6, wherein the control device (50) is further configured to control the flow rate of consumed dialysate to the feed side (2a) and / or the flow rate of the dialysate concentrate to the draw side (2b) based on one or more sensed pressures indicating the hydrostatic pressure difference, such that the hydrostatic pressure difference is kept below the maximum allowable hydrostatic pressure difference.

10. The apparatus (1) according to claim 1, wherein one or more characteristic sensors are configured to sense one or more of the following: the concentration of the diluted dialysis concentrate, the concentration of the dehydrated consumed dialysis fluid, the weight of the diluted dialysis concentrate measured by a weighing scale, the weight of the dehydrated consumed dialysis fluid measured by a weighing scale, the flow rate of the diluted dialysis concentrate, and the flow rate of the dehydrated consumed dialysis fluid.

11. The apparatus (1) according to claim 1, wherein the one or more pressure pumps (7, 32) include a first pressure pump (7) configured to operate on the consumed dialysate output from the feed side (2a).

12. The apparatus (1) according to claim 11, wherein the first pressure pump (7) is configured to pump in either the upstream or downstream direction.

13. The apparatus (1) according to claim 1, wherein the one or more pressure pumps (7, 32) include a second pressure pump (32) configured to operate on the diluted dialysis concentrate solution output from the draw side (2b).

14. The apparatus (1) according to claim 1, wherein at least one of the one or more pressure pumps (7, 32) is a non-positive displacement pump.

15. The apparatus (1) according to claim 1, wherein at least one of the one or more pressure pumps (7, 32) is a positive displacement pump.

16. The apparatus (1) according to claim 1, wherein the control device (50) is configured to control the flow rate of a second or third concentrate (18) so that it flows into the diluted dialysis concentrate to form a dialysate.

17. The apparatus (1) according to claim 1, wherein the apparatus (1) is configured to provide pure water to the diluted dialysis concentrate to form a dialysate.

18. A method for producing dialysate, (S1) Provides the flow of the dialysis concentrate to the draw side (2b) of the forward osmosis (FO) unit (2), (S2) provides the flow of consumed dialysate to the feed side (2b) of the FO unit (2), The osmotic pressure difference between the draw side (2b) and the feed side (2a) causes water to be transported from the consumed dialysate through the FO membrane (2c) of the FO unit (2) to the dialysate concentrate, thereby diluting the dialysate concentrate into a diluted dialysate concentrate and dehydrating the consumed dialysate into a dehydrated consumed dialysate (S2). Using one or more pressure pumps (7, 32), a hydrostatic pressure difference is provided between the draw side (2b) and the feed side (2a) (S3), (S4) Sensing one or more characteristics of the diluted dialysis concentrate and / or the dehydrated consumed dialysis fluid, (S5) sensing one or more pressures indicating the hydrostatic pressure difference between the draw side (2b) and the feed side (2a), A method for producing the diluted dialysis concentrate, comprising controlling at least one of the following based on one or more characteristics of the diluted dialysis concentrate and / or the dehydrated consumed dialysis fluid and one or more sensed pressures indicating the hydrostatic pressure difference (S6): the flow rate of the consumed dialysis fluid to the feed side (2a), the flow rate of the dialysis concentrate to the draw side (2b), and the hydrostatic pressure difference.

19. The method according to claim 18, wherein the control (S6) is The flow rate of consumed dialysate to the feed side (2a) is controlled based on the available volume of consumed dialysate and the length of time available to generate a desired amount of the diluted dialysate concentrate. Based on the volume of the dialysis concentrate required to produce the desired amount of diluted dialysis concentrate and the length of the period, the flow rate of the dialysis concentrate to the draw side (2b) is controlled, A method comprising providing the desired amount of diluted dialysis concentrate at the end of the aforementioned period.

20. A method according to claim 19, comprising controlling the hydrostatic pressure difference using one or more pressure pumps (7, 32) based on one or more characteristics of the diluted dialysis concentrate and / or dehydrated consumed dialysis fluid and one or more sensed pressures indicating the hydrostatic pressure difference.

21. A method according to claim 20, comprising controlling the hydrostatic pressure difference using one or more pressure pumps (7, 32) based on one or more sensed pressures to achieve a predetermined hydrostatic pressure difference (S6).

22. A method according to claim 21, wherein the predetermined hydrostatic pressure difference is the maximum allowable hydrostatic pressure difference.

23. A method according to claim 20, comprising controlling the hydrostatic pressure difference using one or more pressure pumps (7, 32) to make the characteristics of the diluted dialysis concentrate and / or dehydrated consumed dialysis fluid equal to a target value of the characteristics.

24. A method according to claim 19, comprising: controlling the flow rate of the diluted dialysis concentrate using a concentrate pump (10) such that the flow rate of the diluted dialysis concentrate is equal to the value obtained by multiplying the inlet flow rate of the dialysis concentrate to the draw side (2b) by a target dilution coefficient; and controlling the flow rate of the diluted dialysis concentrate using a second pressure pump (32) of the one or more pressure pumps (7, 32) (S6).

25. A method according to claim 24, comprising controlling the ratio between the concentrate pump (10) and the second pressure pump (32) to make the characteristics of the diluted dialysis concentrate equal to a target value of the characteristics.

26. A method according to claim 23, comprising controlling the flow rate of consumed dialysate to the feed side (2a) and / or the flow rate of the dialysate concentrate to the draw side (2b) (S6) based on one or more sensed pressures indicating the hydrostatic pressure difference such that the hydrostatic pressure difference is kept below the maximum allowable hydrostatic pressure difference.

27. A method according to claim 18, wherein sensing one or more characteristics of the diluted dialysis concentrate and / or dehydrated consumed dialysis fluid (S4) includes sensing one or more of the concentration of the diluted dialysis concentrate, the concentration of the dehydrated consumed dialysis fluid, the weight of the diluted dialysis concentrate measured by a weighing scale, the weight of the dehydrated consumed dialysis fluid measured by a weighing scale, the flow rate of the diluted dialysis concentrate, and the flow rate of the dehydrated consumed dialysis fluid.

28. A method according to claim 18, comprising controlling the flow rate of a second or third concentrate (18) so that it flows into the diluted dialysis concentrate to form a dialysate.

29. A computer program comprising instructions for causing the apparatus (1) according to any one of claims 1 to 17 to perform the method according to any one of claims 18 to 28.

30. A computer-readable medium storing the computer program described in claim 29.

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