# US 2023/0054094 A1 · Method and system for preparing dialysis fluid from raw water

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- Number: US 2023/0054094 A1
- Document ID: US20230054094A1
- Status: Published application
- Kind: A1
- Application number: 17/628,428
- Filed: 2020-07-20
- Published: 2023-02-23
- Earliest claimed: 2019-07-22
- Assignees: Baxter International Inc.; Baxter Healthcare S.A.
- Applicants: Baxter International Inc.; Baxter Healthcare SA
- Inventors: Tao HE; Shuwei ZHAO; Pengjia DOU; Jianfeng SONG; Markus STORR; Bernd KRAUSE
- Web page: https://patentgrep.com/patent/US20230054094A1

## CPC

- B01D 61/0022: {Apparatus therefor}
- A61M 1/14: Dialysis systems; Artificial kidneys; Blood oxygenators (semi-permeable membranes characterised by the material, manufacturing processes therefor B01D71/00){; Reciprocating systems for treatment of body fluids, e.g. single needle systems for hemofiltration or pheresis}
- A61M 1/1656: {Apparatus for preparing dialysates}
- B01D 63/031: {Two or more types of hollow fibres within one bundle or within one potting or tube-sheet}
- B01D 69/1216: {Three or more layers}
- B01D 69/1251: {by interfacial polymerisation}
- B01D 71/56: Polyamides, e.g. polyester-amides
- B01D 71/68: Polysulfones; Polyethersulfones
- A61M 1/1672: {using membrane filters, e.g. for sterilising the dialysate}
- B01D 2315/22: Membrane contactor
- B01D 2325/0231: Dense layers being placed on the outer side of the cross-section
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)}

## Abstract

The present disclosure relates to hollow fiber membrane filtration devices for the production of ready-to-use dialysis fluid by forward osmosis, and a cost-efficient and simple method and system for preparing ready-to-use dialysis fluid from raw water and liquid dialysis concentrate by forward osmosis.

## Claims

### Claim at position 1

1-18. (canceled)

### Claim at position 2

19: A hollow fiber membrane filtration device for the generation of ready-to-use dialysis fluid for use in hemodialysis by forward osmosis, the membrane filtration device comprising:
a plurality of hollow fibers axially extending through a cylindrical housing and being embedded and held, at their open ends, in a moulding compound, thereby isolating said hollow fibers from a first fluid chamber defined by the outer surface of said hollow fibers and the inner surface of said housing, wherein said first fluid chamber has a first fluid inlet and a first fluid outlet, both provided on the housing, and further comprising a second fluid inlet and a second fluid outlet in communication with a second fluid chamber defined by the interior of the hollow fibers, and
wherein the hollow fibers include a composite membrane comprising a hollow fiber support membrane including (i) 80-99% by weight of at least one hydrophobic polymer selected from the group consisting of polysulfone (PS), polyethersulfone (PES) and polyarylethersulfone (PAES), (ii) 1-20% by weight of polyvinylpyrrolidone (PVP), and (iii) a polyamide layer on the lumen side of the hollow fiber support membrane.

### Claim at position 3 (depends on 19)

20: The hollow fiber membrane filtration device of claim 19, wherein the composite hollow fiber membrane is configured to allow a permeate flow rate of between 10.0 L/hm2 to 20.0 L/hm2.

### Claim at position 4 (depends on 19)

21: The hollow fiber membrane filtration device of claim 19, wherein the composite hollow fiber membrane has a salt permeability coefficient of between 0.14 L/m2 h and 0.24 L/m2 h.

### Claim at position 5 (depends on 19)

22: The hollow fiber membrane filtration device of claim 19, wherein the composite hollow fiber membrane has a total wall thickness of from 27 μm to 50 μm and an inner diameter of from 170 μm to 230 μm.

### Claim at position 6 (depends on 19)

23: The hollow fiber membrane filtration device of claim 19, wherein the composite hollow fiber membrane comprises a hollow fiber support membrane having an asymmetric three-layer structure consisting of a dense layer on the lumen side of the hollow fiber having a thickness of below 0.6 followed by a support layer having a sponge structure and a thickness of from 1 to 15 and a third layer having a finger-structure and a thickness of from 25 to 50 and a polyamide layer having a thickness of from 5 nm to 500 nm which is present on the dense layer on the lumen side of the hollow fiber.

### Claim at position 7 (depends on 19)

24: The hollow fiber membrane filtration device of claim 19, wherein the total usable membrane surface area is between 1.5 and 2.8 m2 and the packing density of the hollow fibers within the housing is between 45% and 70%.

### Claim at position 8 (depends on 19)

25: The hollow fiber membrane filtration device of claim 19, wherein the polyamide layer is configured to be applied to the lumen side of the hollow fiber support membrane, and consists of products by interfacial polymerisation.

### Claim at position 9 (depends on 19)

26: A process for preparing the hollow fiber membrane filtration device of claim 19, the process comprising:
a) contacting the lumen side of a hollow fiber support membrane with an aqueous m-phenylenediamine (MPD) solution;
b) allowing the MPD solution to contact the surface for 1 to 4 minutes;
c) removing excess MPD solution by blow-drying the interior of the fibers with an inert gas;
d) contacting the interior side of the hollow fiber membranes with a TMC-hexane solution;
e) allowing the TMC-hexane solution to contact the surface for 0.5 to 2 minutes;
f) circulating hot water with a temperature of from 85° C. to 95° C. in the lumen of the hollow fiber membranes for 3 to 10 min to cure the nascent polyamide layer, wherein the polyamide layer consists of products of the m-phenylenediamine (MPD) and the TMC-hexane by interfacial polymerization; and
g) optionally storing the hollow fiber membranes in deionized water before further use.

### Claim at position 10 (depends on 26)

27: The process of claim 26, wherein step (f) alternatively comprises storing the hollow fiber membranes or hollow fiber membrane filtration device in an oven at a temperature of 100° C.±20° C.

### Claim at position 11

28: A method of preparing ready-to-use dialysis fluid from raw water by forward osmosis, the method comprising:
a) providing a hollow fiber membrane filtration device comprising a plurality of forward osmosis hollow fiber membranes axially extending through a cylindrical housing and being embedded and held, at their open ends, in a moulding compound, thereby isolating said hollow fibers from a first fluid chamber defined by the outer surface of said hollow fibers and the inner surface of said housing, wherein said first fluid chamber has an first fluid inlet and a first fluid outlet, both provided on the housing, and further comprising a second fluid inlet and a second fluid outlet in communication with a second fluid chamber defined by the interior of the hollow fibers;
b) passing raw water through the second fluid chamber of the filter device, while recirculating a liquid dialysis concentrate through the first fluid chamber in a countercurrent, thereby creating a flux of pure water from the lumen side of the composite hollow fiber membrane into the dialysis concentrate;
c) terminating recirculation upon reaching the target concentration of the dialysis solution; and
d) providing the ready-to-use dialysis fluid for use in an extracorporeal hemodialysis circuit.

### Claim at position 12 (depends on 28)

29: The method of claim 28, wherein more than one hollow fiber membrane filtration devices are applied in parallel or in series.

### Claim at position 13 (depends on 28)

30: The method of claim 28, wherein the liquid dialysis concentrate comprises at least one substance chosen from the group consisting of glucose, bicarbonate, potassium, acetate, lactate, citrate, pyruvate, carbonate, magnesium, calcium, sodium, sulphate, phosphate, chloride and amino acids.

### Claim at position 14 (depends on 30)

31: The method of claim 30, wherein the liquid dialysis concentrate comprises at least one substance chosen from the group consisting of acetate, lactate, citrate and glucose.

### Claim at position 15 (depends on 30)

32: The method of claim 30, wherein the liquid dialysis concentrate comprises at least one substance chosen from the group consisting of bicarbonate, sodium and chloride.

### Claim at position 16 (depends on 28)

33: The method of claim 28, wherein at least one electrolyte detector is provided in the circuit, optionally after the hollow fiber membrane filtration device.

### Claim at position 17

34: A system for preparing ready-to-use dialysis fluid, the system comprising:
(a) a hollow fiber membrane filtration device comprising a plurality of forward osmosis hollow fiber membranes axially extending through a cylindrical housing and being embedded and held, at their open ends, in a moulding compound, thereby isolating said hollow fibers from a first fluid chamber defined by the outer surface of said hollow fibers and the inner surface of said housing, wherein said first fluid chamber has an first fluid inlet and a first fluid outlet, both provided on the housing, and further comprising a second fluid inlet and a second fluid outlet in communication with a second fluid chamber defined by the interior of the hollow fibers;
(b) a dialysis concentrate feed line connected to the inlet of the first fluid chamber of the hollow fiber membrane filtration device for providing dialysis concentrate from a container;
(c) a dialysis concentrate return line connected to the outlet of the first fluid chamber of the hollow fiber filtration device for returning the diluted dialysis concentrate to the container;
(d) a raw water supply line connected to the inlet of the second fluid chamber of the hollow fiber membrane filtration device;
(e) a raw water effluent line connected to the outlet of the second fluid chamber of the hollow fiber membrane filtration device; and
(f) an electrolyte detector in the dialysis concentrate return line,
wherein the hollow fiber members consist of a composite membrane comprising a hollow fiber support membrane including (i) 80-99% by weight of at least one hydrophobic polymer selected from the group consisting of polysulfone (PS), polyethersulfone (PES) and polyarylethersulfone (PAES), (ii) 1-20% by weight of polyvinylpyrrolidone (PVP), and (iii) a polyamide layer on a lumen side of the hollow fiber support membrane.

### Claim at position 18 (depends on 34)

35: The system of claim 34, further comprising a control system configured to run the preparation of the ready-to-use dialysis fluid, comprising pumping means for passing raw water through the second fluid chamber of the hollow fiber membrane filtration device and for recirculating dialysis concentrate through the first fluid chamber of the hollow fiber membrane filtration device, the control unit being connected to at least one electrolyte detector and configured to receive a value representative of the conductivity of the dialysis fluid, wherein said control unit is configured to terminate the recirculation of the dialysis concentrate at a set conductivity value which indicates that the target concentration of the ready-to-use dialysis fluid has been reached.

### Claim at position 19 (depends on 34)

36: The system of claim 34, wherein the conductivity of the dialysis fluid or the concentration of at least one substance in the dialysis fluid is determined, said substance including sodium.