Ultrafiltration membrane device

Abstract

To provide an ultrafiltration membrane device capable of suppressing the proliferation of bacteria even when concentrated water is retained or the linear velocity of the concentrated water is reduced in an outflow part of the concentrated water.SOLUTION: An ultrafilter membrane device 1 that ultrafilters water W1 to be treated to obtain permeated water includes a hollow fiber membrane 2, a housing 3 that houses the hollow fiber membrane 2, an outflow part 4 for concentrated water W3 provided in the housing 3, and a flow path 5 connected to the outflow part 4 for concentrated water W3, in which a flow path size of the flow path 5 from a 4b connected to the outflow part 4 for concentrated water W3 to a control valve 11 installed closest to the ultrafilter membrane device 1 is 4 to 10mm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an ultrafiltration membrane device. [Background technology]

[0002] In the electronics industry, where products such as liquid crystal display panels and semiconductors are manufactured, ultrapure water is required for cleaning and other stages of the manufacturing process. A typical production system for ultrapure water includes a pretreatment system, a primary pure water system, and a secondary pure water system (hereinafter, the secondary pure water system may be referred to as a subsystem). The subsystem often includes, in order of water flow direction, an ultraviolet oxidation device, a non-regenerative ion exchange resin device, and an ultrafiltration membrane device to remove trace amounts of ions, live bacteria, solids, and the like from the pure water.

[0003] Regarding ultrafiltration membrane devices, Patent Document 1 listed below describes an ultrapure water production system having multiple ultrafiltration membrane modules connected in series, in which the amount of concentrated water from the ultrafiltration membrane module in the latter stage of the multiple ultrafiltration membrane modules connected in series is set to be smaller than the amount of concentrated water from the ultrafiltration membrane module in the former stage. Patent Document 1 also describes that the amount of concentrated water from the ultrafiltration membrane module in the latter stage is set to 1% by volume or less of the water to be treated supplied to the ultrafiltration membrane module in the latter stage. Patent Document 1 further describes that some or all of the multiple ultrafiltration modules constituting the latter stage may be operated in full filtration mode.

[0004] Here, as described in Patent Document 1, when an ultrafiltration membrane module is used for dead-end filtration operation in which the concentrated water is not discharged, or when the concentrated water flow rate is set to 1% by volume or less of the feed water flow rate, the concentrated water will accumulate in the outlet of the ultrafiltration membrane module, or the linear velocity of the concentrated water in the outlet will decrease significantly.

[0005] In the outflow section where concentrated water accumulates or the linear velocity of the concentrated water decreases, there is a concern that bacterial cells may grow, and furthermore, there is a concern that the performance of the ultrafiltration membrane may be reduced by the grown bacterial cells themselves or metabolic components produced by the bacterial cells, which may in turn lead to a concern that the quality of the ultrapure water may be reduced.

[0006] Furthermore, trace amounts of components from the components of the ultrafiltration membrane module are eluted over time. These eluted components reach high concentrations in stagnant concentrated water or concentrated water with a reduced linear velocity, and similar to the effects of the bacteria described above, there are concerns that they may cause a decrease in the performance of the ultrafiltration membrane or a decrease in the quality of the ultrapure water.

[0007] In practice, a pipe is connected to the outlet of the concentrated water from the ultrafiltration membrane module, and an on-off valve and a flow control valve are installed downstream of the pipe. Therefore, the area in which concentrated water stagnates or the linear velocity of the concentrated water decreases is not limited to the outlet of the ultrafiltration membrane module, but extends to the inside of the pipe connected to the outlet up to the installation position of the on-off valve and the flow control valve, and the volume inside this pipe is unlikely to be negligible.

[0008] Furthermore, Patent Document 2 shows that adhering fine particles can be effectively discharged by setting the linear velocity within the hollow fiber membrane to 0.3 m / s or more. This patent document suggests that maintaining the linear velocity in the flow path at a certain level or higher, specifically maintaining a linear velocity of 0.3 m / s or more, is an effective method for suppressing the adverse effects caused by bacteria and fine particles. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 6469400 [Patent Document 2] Patent No. 3071870 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an ultrafiltration membrane device that can suppress the growth of bacterial cells even when concentrated water stagnates or the linear velocity of the concentrated water decreases at the outlet of the concentrated water. [Means for solving the problem]

[0011] In order to solve the above problems, the following configuration is adopted. [1] An ultrafiltration membrane device that ultrafilters water to be treated to obtain permeate, A hollow fiber membrane; a housing that houses the hollow fiber membrane; An outlet for concentrated water provided in the housing; A flow path connected to the outlet of the concentrated water, An ultrafiltration membrane device, wherein the flow path from the connection with the outlet of the concentrated water to the control valve installed closest to the ultrafiltration membrane device has a flow path diameter of 4 to 10 mm. [2] An ultrafiltration membrane device that ultrafilters water to be treated to obtain permeate, A hollow fiber membrane; a housing that houses the hollow fiber membrane; An outlet for concentrated water provided in the housing, The outlet of the concentrated water is a tubular portion connected to the housing and through which the concentrated water flows; an outlet for the concentrated water provided at the tip of the tubular portion, The inner diameter of the tubular part is 4 to 10 mm. [3] The outlet of the concentrated water is a tubular portion connected to the housing and through which the concentrated water flows; an outlet for the concentrated water provided at the tip of the tubular portion, The ultrafiltration membrane device according to [1], wherein the inner diameter of the tubular part is 4 to 10 mm. [4] The ultrafiltration membrane device according to any one of [1] to [3], wherein the flow rate of the concentrated water is 1% or less of the flow rate of the water to be treated supplied to the ultrafiltration membrane device. [Effects of the Invention]

[0012] According to the present invention, an ultrafiltration membrane device can be provided that can suppress the growth of bacterial cells even when concentrated water stagnates or the linear velocity of the concentrated water decreases in the concentrated water discharge section. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional schematic diagram showing an example of an ultrafiltration membrane device according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional schematic diagram showing an example of a main part of an ultrafiltration membrane device according to an embodiment of the present invention. [Figure 3] FIG. 2 is a cross-sectional schematic view showing another example of the main part of the ultrafiltration membrane device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Conventional ultrafiltration membrane devices used in subsystems of ultrapure water production systems generally have a flow rate of 10 to 15 m 3 / h, and the flow rate of concentrated water is 0.5 to 1.5 m 3 / h. In this case, the flow rate of the concentrated water is about 5 to 10% by volume of the flow rate of the water to be treated. In addition, the nominal diameter of the concentrated water outlet in conventional ultrafiltration membrane devices is set to 25A to 40A in order to accommodate the above-mentioned flow rate of the concentrated water.

[0015] However, in order to ensure a sufficient flow rate of ultrapure water, dead-end filtration operation may be performed in which the concentrated water is not discharged, or the flow rate of the concentrated water may be set to 1% by volume or less of the feed water flow rate. Operation under such conditions may result in the concentrated water remaining near the concentrated water outlet of the ultrafiltration membrane device, or the linear velocity of the concentrated water may be significantly reduced, which may lead to the generation of bacterial cells.

[0016] The present inventors have conducted research and found that the generation of bacteria can be suppressed by adopting a configuration in an ultrafiltration membrane device that can ensure a certain linear velocity of concentrated water or more.

[0017] The ultrafiltration membrane device 1 of this embodiment is provided, for example, in a subsystem of an ultrapure water production system. The ultrafiltration membrane device 1 of this embodiment shown in Figure 1 is capable of obtaining permeate W2 and concentrated water W3 by filtering water to be treated W1 through a hollow fiber membrane 2. The ultrafiltration membrane device 1 of this embodiment will be described in detail below with reference to Figure 1. Figure 1 is a cross-sectional schematic diagram of an example of the ultrafiltration membrane device of this embodiment.

[0018] As shown in Figure 1, the ultrafiltration membrane device 1 includes a hollow fiber membrane 2, a housing 3, an outlet 4 for concentrated water W3 provided in the housing 3, and a flow path 5 connected to the outlet 4 for concentrated water W3.

[0019] The hollow fiber membrane 2 is, for example, an ultrafiltration membrane (UF membrane). An example of a UF membrane is one having pores of 0.005 to 0.5 μm. There are no particular limitations on the hollow fiber membrane 2, but typically, one having an inner diameter of 0.2 to 1.0 mm, an outer diameter of 0.5 to 2.0 mm, and an effective length of about 300 to 2500 mm is used. There are also no particular limitations on the membrane material of the UF membrane, but polysulfone, PVDF (polyvinylidene fluoride), polyethylene, polypropylene, etc. can be used.

[0020] The housing 3 is, for example, a hollow cylindrical shape, and is arranged with the axial direction of the cylinder in the up-down direction (vertical direction in this embodiment). A plurality of hollow fiber membranes 2 are housed inside the housing 3.

[0021] The hollow fiber membranes 2 are fixed to the upper side of the housing 3 by a synthetic resin potting part 6 as a fixing part, but are not fixed to the lower side of the housing 3. The synthetic resin for the potting part 6 can be, for example, epoxy resin. For example, the hollow fiber membranes 2 are assembled into a U-shape, and both ends of the hollow fiber membranes 2 are fixed by the potting parts 6. In this case, the middle part of the hollow fiber membranes 2 is located at the lower part of the housing 3.

[0022] The potting portion 6 is, for example, disk-shaped, and its outer circumferential surface or outer circumferential edge is in watertight contact with the inner surface of the housing 3 .

[0023] Inside the housing 3, a permeate chamber 7 and a treated water chamber 10 are defined above and below the potting part 6, respectively. The upper end side of the hollow fiber membrane 2 passes through the potting part 6, and the opening at the upper end faces the permeate chamber 7, with the interior of the hollow fiber membrane 2 communicating with the permeate chamber 7. As a result, the treated water chamber 10 serves as the primary side of the hollow fiber membrane 2, and the permeate chamber 7 serves as the secondary side of the hollow fiber membrane 2.

[0024] The housing 3 is provided with an inlet 8 for the water to be treated W1, an outlet 9 for the permeated water W2, and an outlet 4 for the concentrated water W3.

[0025] The inlet 8 for the water to be treated W1 provided in the housing 3 is composed of a tubular portion 8a that protrudes from the bottom of the housing 3 and communicates with the water to be treated chamber 10. An inlet 8b for the water to be treated W1 is opened at the tip of the tubular portion 8a. Since the tubular portion 8a is communicated with the water to be treated chamber 10, the water to be treated W1 flows into the water to be treated chamber 10 from the tubular portion 8a.

[0026] The outlet 9 for the permeated water W2 provided in the housing 3 is composed of a tubular portion 9a that protrudes from the top of the housing 3 and communicates with the permeated water chamber 7. An outlet 9b for the permeated water W2 is opened at the tip side of the tubular portion 9a. Because the tubular portion 9a is in communication with the permeated water chamber 7, the permeated water W2 obtained by the filtration process passes through the permeated water chamber 7 and the tubular portion 9a and is taken out of the system.

[0027] The outlet 4 for the concentrated water W3 provided in the housing 3 is composed of a tubular portion 4a that protrudes from the housing 3 and communicates with the water-to-be-treated chamber 10. An outlet 4b for the concentrated water W3 opens at the tip of the tubular portion 4a. Since the tubular portion 4a is in communication with the water-to-be-treated chamber 10, the concentrated water W3 obtained by filtration can be taken out of the system through the tubular portion 4a. The inner diameter of the tubular portion 4a is in the range of 4 to 10 mm, and is set to an inner diameter that allows the concentrated water to have a linear velocity of 0.3 m / s or more.

[0028] A flow path 5 for the concentrated water W3 is connected to the outlet 4 for the concentrated water W3. The flow path 5 is, for example, a cylindrical pipe. A control valve 11 for controlling the flow rate of the concentrated water W3 is attached midway along the flow path 5. The control valve 11 is, for example, a flow adjustment valve or an on-off valve. Multiple control valves may be installed in the flow path 5 for the concentrated water W3 as needed, but the control valve 11 shown in FIG. 1 is installed closest to the ultrafiltration membrane device 1.

[0029] The flow path diameter of the flow path 5 from the connection with the outlet 4b of the concentrated water W3 to the control valve 11 installed closest to the ultrafiltration membrane device is in the range of 4 to 10 mm, and is set to a flow path diameter that allows a linear velocity of the concentrated water of 0.3 m / s or more to be obtained.

[0030] In the ultrafiltration membrane device 1 shown in Figure 1, water to be treated W1 flows into the water to be treated chamber 10 from the water to be treated inlet 8, and a portion of the inflowing water to be treated W1 is filtered by the hollow fiber membrane 2 to become permeate W2, which passes through the permeate chamber 7 and is taken out from the permeate outlet 9. The remainder of the water to be treated W1 that flows into the water to be treated chamber 10 becomes concentrated water W3, which is taken out from the concentrated water W3 outlet 4 and flows into the flow path 5. The concentrated water W3 further passes through the control valve 11 and is sent out of the system.

[0031] The ultrafiltration membrane device 1 of this embodiment may be installed, for example, in a subsystem of an ultrapure water production system and may perform a dead-end filtration operation in which the concentrated water is not discharged, or an operation in which the concentrated water flow rate is set to 1% by volume or less of the feedwater flow rate. Even in such cases, according to this embodiment, as described above, the flow path diameter of the flow path 5 from the outlet 4b (the connection between the outlet 4 and the flow path 5) to the control valve 11 is set to a range of 4 to 10 mm, which is a flow path diameter that allows the concentrated water to flow at a linear velocity of 0.3 m / s or more. This ensures that the concentrated water W3 flowing through the flow path 5 has a sufficient flow velocity, thereby suppressing the generation of bacterial cells due to the retention of the concentrated water W3 or a decrease in linear velocity in the flow path 5. Furthermore, the increase in the concentration of eluted components eluted from the materials constituting the flow path 5 is also suppressed.

[0032] Furthermore, in the ultrafiltration membrane device 1 of this embodiment, the inner diameter of the tubular portion 4a constituting the outlet portion 4 for the concentrated water W3 is set to a range of 4 to 10 mm, an inner diameter that allows the concentrated water W3 to flow at a linear velocity of 0.3 m / s or more. This ensures that the concentrated water W3 flowing through the tubular portion 4a has a sufficient flow velocity, suppressing the generation of bacterial cells due to retention of the concentrated water W3 in the tubular portion 4a or a decrease in linear velocity. Furthermore, the increase in concentration of eluted components eluted from the material constituting the outlet portion 4 is also suppressed.

[0033] In the ultrafiltration membrane device 1 of this embodiment, it is not necessary for both the inner diameter of the tubular portion 4a and the flow path diameter of the flow path 5 to be in the range of 4 to 10 mm; either the inner diameter of the tubular portion 4a or the flow path diameter of the flow path 5 may be in the range of 4 to 10 mm.

[0034] Next, a specific example of the ultrafiltration membrane device 1 of this embodiment will be described. FIG. 2 shows the main parts of an ultrafiltration membrane device that is a specific example of this embodiment. In the ultrafiltration membrane device 21 shown in FIG. 2, a housing 23 is provided with an outflow portion 24 for the concentrated water W3.

[0035] This outflow section 24 is composed of a tubular section 24a, a closure plate 24c arranged at the tip side of the tubular section 24a, a rubber O-ring 24d arranged between the tubular section 24a and the closure plate 24c, a cap nut 24e for fixing the closure plate 24c to the tip of the tubular section 24a, and a through hole 24g for a nipple attached to the closure plate 24c as a flow path.

[0036] An outlet 24b for the concentrated water W3 is opened at the tip of the tubular portion 24a. The closing plate 24c has a disk-shaped outer shape and is attached to the tubular portion 24a so as to close the outlet 24b. A through hole 24g is provided in the center of the closing plate 24c, and the inner circumferential surface of the through hole 24g is an internally threaded portion. A nipple 25 is attached to this through hole 24g. A control valve 31 is attached to the nipple 25 on the side opposite the closing plate 24c. The tubular portion 24a and the cap nut 24e are connected and fixed by the male and female threads provided thereon, respectively.

[0037] The nipple 25 is a hollow cylindrical pipe joint, and a hollow portion 25a serves as a flow path for the concentrated water W3. Two externally threaded portions 25b, 25c are provided on the outer peripheral surface of the nipple 25. One of the externally threaded portions 25b is fitted into the internally threaded portion of the through-hole 24g of the closure plate 24c. This connects the nipple 25 to the outlet portion 24 for the concentrated water W3 via the closure plate 24c.

[0038] The other male threaded portion 25c of the nipple 25 is attached to the control valve 31. In this way, the nipple 25 is connected to the control valve 31.

[0039] The inner diameter (flow path diameter of concentrated water) of the hollow portion 25a of the nipple 25 is set in the range of 4 to 10 mm, and is set to a flow path diameter that allows a linear velocity of concentrated water of 0.3 m / sec or more to be obtained.

[0040] In the ultrafiltration membrane device 21 shown in Fig. 2, concentrated water W3 passes through the tubular portion 24a and further through the hollow portion 25a of the nipple 25 to reach the control valve 31. The inner diameter of the hollow portion 25a of the nipple 25 is set in the range of 4 to 10 mm, and is set to a flow path diameter that allows the concentrated water to have a linear velocity of 0.3 m / sec or more, thereby suppressing the generation of bacterial bodies and the increase in the concentration of eluted components.

[0041] Although there are no particular restrictions on the materials for the closure plate 24c and the nipple 25, materials with low elution components and excellent pressure resistance are preferred. Specific examples of such materials include polyvinyl chloride (PVC), clean polyvinyl chloride (clean PVC), polyether ketone (PEEK), polystyrene (ABS, etc.), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), perfluoroalkoxyalkane (PFA), and polypropylene (PP).

[0042] Furthermore, from the viewpoint of pressure resistance, it is considered that the closing plate 24c may need to be made of a metal material. When a metal closing plate 24c is used and there is a concern about metal elution, the influence can be minimized by lining the surface of the metal closing plate 24c on the outflow portion 24 side with a low-elution material. Examples of lining materials include the materials of the closing plate 24c and the nipple 25 described above.

[0043] Next, FIG. 3 shows the main part of an ultrafiltration membrane device which is another specific example of this embodiment. In the ultrafiltration membrane device 41 shown in FIG. 3, a housing 43 is provided with an outflow portion 44 for the concentrated water W3.

[0044] This outflow section 44 is composed of a tubular section 44a, a hollow cylindrical flow path adjustment member 44c inserted into the tubular section 44a, two rubber O-rings 44d sandwiched between the inner surface of the tubular section 44a and the outer surface of the flow path adjustment member 44c, a rubber O-ring 44e sandwiched between the tip surface of the tubular section 44a and the flow path adjustment member 44c, and a cap nut 44g for fixing the flow path adjustment member 44c to the tubular section 44a.

[0045] The flow path adjustment member 44c is used as a spacer for adjusting the inner diameter of the tubular portion 44a. A through hole 44f is provided in the flow path adjustment member 44c, and this through hole 44f serves as a flow path for the concentrated water W3 in the outflow portion 44. The through hole 44f is in communication with the interior of the housing 43. A control valve 51 is attached to the side of the flow path adjustment member 44c opposite to the housing 43 side.

[0046] The tubular portion 44a and the cap nut 44g are connected and fixed by the male and female threads provided thereon, respectively.

[0047] The flow path adjusting member 44c and the control valve 51 are connected and fixed by a female thread portion and a male thread portion provided on each of them.

[0048] There is no particular restriction on the depth d from the concentrated water outlet 44b when inserting the flow path adjustment member 44c into the tubular portion 44a of the outflow section 44, but from the standpoint of reducing the amount of concentrated water that remains, it is preferable that the depth d be 50% or more, preferably 80% or more, of the length L from the concentrated water outlet opening inside the housing 3 to the concentrated water outlet section 44b of the tubular portion 44a.

[0049] The inner diameter of the through-hole 44f of the flow path adjusting member 44c (the flow path diameter of the concentrated water) is set in the range of 4 to 10 mm, and is set to a flow path diameter that allows the concentrated water to have a linear velocity of 0.3 m / sec or more.

[0050] 3, the concentrated water W3 flows through a through-hole 44f of a flow path adjusting member 44c inserted into a tubular portion 44a and reaches a control valve 51. The inner diameter of the through-hole 44f of the flow path adjusting member 44c is set to a flow path diameter that allows the concentrated water to flow at a linear velocity of 0.3 m / sec or more, thereby suppressing the generation of bacterial bodies and the increase in the concentration of eluted components.

[0051] The flow path adjusting member 44c may be made of the same material as the closing plate 24c and the nipple 25 described above.

[0052] In the ultrafiltration membrane devices 1, 21, and 41 shown in FIGS. 1 to 3, the flow rate of permeated water is 10 to 15 m 3When obtaining a flow rate of 0.1 to 1% by volume of the concentrated water W3 in relation to the flow rate of the water to be treated, the flow rate of the concentrated water is 0.015 to 0.15 m 3 The inner diameter of the outflow portions 4, 24, 44 or the flow path diameter of the flow paths 5, 25 for the concentrated water to have a linear velocity of 0.3 m / s or more at this flow rate range is preferably in the range of 4 to 10 mm.

[0053] More preferably, the permeate flow rate is 10 m 3 When obtaining a flow rate of 0.5% by volume of the water to be treated, the flow rate of the concentrated water is 0.05 m 3 / h, so the inner diameter or flow path diameter at which the linear velocity of the concentrated water is 0.3 m / s or more should be 6 mm.

[0054] Furthermore, in the ultrafiltration membrane devices 1, 21, 41 shown in Figures 1 to 3, when dead-end filtration is assumed in which the flow rate of concentrated water is set to zero, it is preferable to place the control valves 11, 31, 51 near the concentrated water outlets 4, 24, 44 as described above to minimize the amount of concentrated water that remains.However, when the flow rate of the concentrated water is passed at a flow rate of 1% by volume or less in relation to the flow rate of the water to be treated that is being supplied, the control valves 11, 31 may be installed at a position slightly away from the concentrated water outlets 4b, 24b via flow paths 5, 25a in which the linear velocity of the concentrated water is 0.3 m / s or more.

[0055] As described above, according to the ultrafiltration membrane devices 1, 21, 41 of the present embodiment, even when the flow rate of the concentrated water is 1% by volume or less of the flow rate of the water to be treated, the linear velocity of the concentrated water is configured to be 0.3 m / s or more, thereby preventing the inner diameter of the concentrated water outlet 4, 24, 44 or the flow path 5, 25 from becoming a stagnation area for the concentrated water, thereby suppressing bacterial growth, high concentration of eluted components, and stagnation of the discharge of fine particles. Furthermore, deterioration of the performance of the hollow fiber membrane 2 and deterioration of the quality of the ultrapure water due to these factors can be avoided.

[0056] Furthermore, according to the ultrafiltration membrane devices 1, 21, and 41 of the present embodiment, even when dead-end filtration is performed to reduce the flow rate of concentrated water to zero, the effects of bacterial proliferation and eluted components can be minimized. [Explanation of symbols]

[0057] 1, 21, 41...Ultrafiltration membrane device, 2...hollow fiber membrane, 3...casing, 4, 24, 44...concentrated water outlet, 4a, 8a, 9a, 24a, 44a...tubular portion, 4b, 24b, 44b...concentrated water outlet (connection portion), 5...flow path, 6...potting portion, 7...permeate chamber, 8...inlet portion of water to be treated, 8b...inlet portion of water to be treated, 9...permeated water outlet, 9b...permeated water outlet, 10...water to be treated chamber, 11, 31, 51...control valve, 24c...closure plate, 24d, 44d, 44e...O-ring, 24e...cap nut, 24g...through hole, 25...nipple (flow path), 25a...hollow portion, 25b, 25c...male thread portion, 44f...through hole, W1...water to be treated, W2...permeated water, W3...concentrated water.

Claims

1. An ultrafiltration membrane device that ultrafilters water to be treated to obtain permeate, A hollow fiber membrane; a housing that houses the hollow fiber membrane; An outlet for concentrated water provided in the housing; A flow path connected to the outlet of the concentrated water, An ultrafiltration membrane device, wherein the flow path from the connection with the outlet of the concentrated water to the control valve installed closest to the ultrafiltration membrane device has a flow path diameter of 4 to 10 mm.

2. An ultrafiltration membrane device that ultrafilters water to be treated to obtain permeate, A hollow fiber membrane; a housing that houses the hollow fiber membrane; An outlet for concentrated water provided in the housing, The outlet of the concentrated water is a tubular portion connected to the housing and through which the concentrated water flows; an outlet for the concentrated water provided at the tip of the tubular portion, The inner diameter of the tubular portion is 4 to 10 mm.

3. The outlet of the concentrated water is a tubular portion connected to the housing and through which the concentrated water flows; an outlet for the concentrated water provided at the tip of the tubular portion, 2. The ultrafiltration membrane device according to claim 1, wherein the inner diameter of the tubular portion is 4 to 10 mm.

4. The ultrafiltration membrane device according to any one of claims 1 to 3, wherein the flow rate of the concentrated water is 1% or less of the flow rate of the water to be treated supplied to the ultrafiltration membrane device.

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