Separation membrane element

Abstract

A separation membrane element in which the line diameter other than the intersection point portion of the net shape of the supply-side flow path member is smaller than the line diameter of the intersection point portion; in a plane parallel to the flow direction of the supplied water and perpendicular to the plane direction of the supply-side flow path member, a point on the outer periphery of a cross-section where the distance between the cross-section other than the intersection point portion and the separation membrane is the smallest is set as P, and a point on the outer periphery of the cross-section is set as P on the downstream side of the supplied water from P. [theta] * (1-Lp / Lq) 2gt, where Q is a point on the outer periphery of the cut surface at which the distance on the same side as the separation membrane is the largest, Lp is the distance between P and the separation membrane, Lq is the distance between Q and the separation membrane, and [theta] is the elevation angle from P to Q; the ratio of the area of the cut surface to the area of a pattern formed by a line segment that protrudes between the outer circumference on the side closer to the separation membrane surface and the outer circumference on the side farther from the separation membrane surface among the outer circumferences connecting P and Q in the cut surface is 70% or more, and Lp is 15% or less of the supply-side flow path thickness.

Description

Technical Field

[0001] The present invention relates to a separation membrane element used for separating impurities from various liquids containing impurities, and particularly used in desalination of seawater, desalination of brackish water, production of ultrapure water, or wastewater treatment, etc. Background Art

[0002] In the technology for removing ionic substances contained in seawater, brackish water, etc., in recent years, as a process for energy saving and resource saving, the use of the separation method by a separation membrane element is expanding. The separation membrane used in the separation method by a separation membrane element is classified into a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, a reverse osmosis membrane, and a forward osmosis membrane according to its pore size and separation function. These membranes are used for, for example, production of drinking water from seawater, brackish water, and water containing harmful substances, production of industrial ultrapure water, and wastewater treatment and recovery of valuable substances, and are used separately according to the separation component and separation performance as the purpose.

[0003] There are various forms of separation membrane elements, but they are common in that raw water is supplied to one surface of the separation membrane and a permeate fluid is obtained from the other surface. The separation membrane element is formed by bundling a large number of separation membranes, so that the membrane area of each separation membrane element becomes larger, that is, the amount of permeate fluid that can be obtained in each separation membrane element becomes larger. As separation membrane elements, various shapes such as a spiral type, a hollow fiber type, a plate and frame type, a rotating flat membrane type, and a flat membrane integrated type have been proposed according to the use and purpose.

[0004] For example, in reverse osmosis filtration, a spiral separation membrane element is widely used. The spiral separation membrane element includes a collecting pipe and a separation membrane unit wound around the collecting pipe. The separation membrane unit is formed by laminating a supply-side flow path member for supplying raw water (i.e., water to be treated) as supply water to the separation membrane surface, a separation membrane for separating components contained in the raw water, and a permeate-side flow path member for guiding the permeate fluid separated from the supply-side fluid through the separation membrane to the collecting pipe. Since the spiral separation membrane element can apply pressure to the raw water, it is preferably used in that a large amount of permeate fluid can be taken out.

[0005] In order to improve the performance of the separation membrane element, it is preferable that the pressure loss of the supply-side flow path can be reduced and the concentration polarization phenomenon in which the salt concentration on the membrane surface locally becomes high due to the concentration of dissolved salts in the supply water on the membrane surface can be suppressed as much as possible without losing the pressure applied to the separation membrane element for filtration use. Therefore, an improvement in the performance of the separation membrane element by the supply-side flow path member has been proposed.

[0006] Specifically, in Patent Document 1, the following network is proposed: The fibers between the intersections of the fibrous materials in the supply-side flow path member are thinner, and the cross-sectional part having a diameter in the direction perpendicular to the flow surface of the supply water is larger than the diameter in the parallel direction, thereby reducing the pressure loss.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-117949 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] However, in the above-described separation membrane element, since a low-speed region of the supply water flow is likely to locally occur on the separation membrane surface, it cannot be said that the concentration polarization phenomenon is sufficiently suppressed, and there is a case where the applied pressure is lost. Therefore, an object of the present invention is to provide a separation membrane element that can suppress the loss of the applied pressure by suppressing the pressure loss and concentration polarization in the supply-side flow path.

[0012] Means for Solving the Problems

[0013] The present invention for solving the above problems and its preferred embodiments are configured as follows.

[0014] [1] A separation membrane element, comprising a header pipe, a separation membrane having a supply-side surface and a permeate-side surface, a supply-side flow path member disposed on the supply-side surface, and a permeate-side flow path member disposed on the permeate-side surface; the separation membrane, the supply-side flow path member, and the permeate-side flow path member are wound around the header pipe; the separation membrane element is characterized in that the supply-side flow path member is a network shape formed by a plurality of fibrous rows X composed of fibrous materials A arranged in one direction and a plurality of fibrous rows Y composed of fibrous materials B arranged in a direction different from the fibrous rows X intersecting three-dimensionally to form intersections; the wire diameter of the fibrous material outside the intersection part of the supply-side flow path member is smaller than the wire diameter of the intersection part; when in a plane parallel to the flow direction of the supply water and perpendicular to the plane direction of the supply-side flow path member, the point on the outer periphery of the cut surface where the distance between the cut surface of at least one of the fibrous materials A and B outside the intersection part and the separation membrane is the smallest is set as P, the point on the outer periphery of the cut surface where the distance in the downstream side of the supply water flow from P and on the same side as the distance from the separation membrane is the largest is set as Q, the distance between P and the separation membrane is set as L p and the distance between Q and the separation membrane is set as L q, when the elevation angle from P to Q is set to θ [°], in more than 50% of the fibrous material other than the intersection part of the supply-side flow path member, the relationship θ×(1−L p / L q ) 2 >15 is satisfied. And if the ratio of the area of the cross-section to the area of the figure formed by the outer circumference l p and the line segment l q ’ is set to α, the outer circumference l p is the outer circumference on the side closer to the separation membrane surface among the outer circumferences connecting P and Q in the cross-section, and the line segment l q ’ is the line segment that convexly encloses the outer circumference l q on the side farther from the separation membrane surface, then α≥70%, and L p is 15% or less of the thickness D C of the supply-side flow path.

[0015] [2] The separation membrane element according to [1] above, characterized in that the relationship θ×(1−L p / L q ) 2 >20 and θ>43° is satisfied.

[0016] [3] The separation membrane element according to [1] above, characterized in that the relationship θ×(1−L p / L q ) 2 >24 and θ>46° is satisfied.

[0017] [4] The separation membrane element according to any one of [1] to [3] above, characterized in that when, in the cross-section, the maximum width in the thickness direction of the supply-side flow path member is set to W 1 , and the distance between the straight line passing through the center in the thickness direction of the cross-section and parallel to the flow direction of the supply water and the straight line passing through the center in the thickness direction of the supply-side flow path and parallel to the flow direction of the supply water is set to W 2 , the relationship W 2 −W 1 / 2≥0 is satisfied.

[0018] [5] The separation membrane element according to any one of [1] to [4] above, characterized in that there is a protrusion at the rear in the flow direction of the supply water in the cross-section.

[0019] [6] The separation membrane element according to any one of [1] to [5] above, characterized in that α≥90%.

[0020] [7] The separation membrane element according to any one of [1] to [6] above, characterized in that the supply-side flow path member is an obliquely crossed net.

[0021] [8] The separation membrane element according to any one of [1] to [7] above, characterized in that the intersection interval of the supply-side flow path member in the flow direction of the supply water is 5 times or more and 10 times or less the thickness of the supply-side flow path member.

[0022] [9] The separation membrane element according to any one of [1] to [7] above, characterized in that the intersection interval of the supply-side flow path member in the flow direction of the supply water is 5 times or more and 7 times or less the thickness of the supply-side flow path member.

[0023]

[10] The separation membrane element according to any one of [1] to [7] above, characterized in that the intersection interval of the supply-side flow path member in the flow direction of the supply water is 8 times or more and 10 times or less the thickness of the supply-side flow path member.

[0024]

[11] A method for filtering a liquid, using the separation membrane element according to any one of [1] to

[10] above.

[0025]

[12] A liquid separation device, using the separation membrane element according to any one of [1] to

[10] above.

[0026] Advantages of the Invention

[0027] According to the present invention, since vortices of supply water are formed on the separation membrane surface, it is possible to suppress concentration polarization on the membrane surface and at the same time suppress pressure loss in the supply water flow path, so that a separation membrane element with excellent water production rate and desalination rate can be obtained. Description of the Drawings

[0028] Figure 1 It is a partially developed perspective view showing an example of a separation membrane element.

[0029] Figure 2 It is a plan view showing an example of the supply-side flow path member of the embodiment.

[0030] Figure 3 It is a cross-sectional view showing an example of the supply-side flow path member of the embodiment.

[0031] Figure 4 It is a cross-sectional view showing an example of the supply-side flow path member.

[0032] Figure 5 It is a cross-sectional view showing an example of the supply-side flow path member of the embodiment.

[0033] Figure 6 (a) to Figure 6(e) is a cross-sectional view taken in a plane parallel to the flow direction of the supply water and perpendicular to the planar direction of the supply-side flow path member, which is an example of the supply-side flow path member of the embodiment.

[0034] Figure 7 (f) to Figure 7 (k) is a cross-sectional view taken in a plane parallel to the flow direction of the supply water and perpendicular to the planar direction of the supply-side flow path member, which is an example of the supply-side flow path member other than the embodiment.

[0035] Figure 8 (l) to Figure 8 (o) is a cross-sectional view taken in a plane parallel to the flow direction of the supply water and perpendicular to the planar direction of the supply-side flow path member, which is an example of the supply-side flow path member other than the embodiment. Detailed Embodiment

[0036] Hereinafter, embodiments of the present invention will be described in detail.

[0037] <Separation Membrane Element>

[0038] The separation membrane element of the present embodiment includes at least a header pipe, a separation membrane, a supply-side flow path member, and a permeate-side flow path member.

[0039] In Figure 1 In the spiral separation membrane element 1 shown, a polymer-made net is used as the supply-side flow path member 2 that forms the flow path on the supply side. In addition, as the permeate-side flow path member 4, a tricot warp knitted fabric having a finer pitch than the supply-side flow path member 2 is used for the purpose of preventing the separation membrane 3 from falling and forming the flow path on the permeate side. A sealed membrane 5 is formed by the permeate-side flow path member 4 and the separation membrane 3 laminated on both sides of the permeate-side flow path member 4 and bonded in an envelope shape. The inside of the sealed membrane 5 constitutes the permeate-side flow path. The sealed membranes 5 laminated alternately with the supply-side flow path member 2 bond a specified portion on the opening side to the outer peripheral surface of the header pipe 6 and wind it in a spiral shape. Figure 1 The direction of the x-axis shown is the length direction of the header pipe 6. In addition, the direction of the y-axis is a direction perpendicular to the length direction of the header pipe 6.

[0040] In the spiral separation membrane element 1, the supply water 7 is supplied from one side surface, and while flowing parallel to the header pipe 6, the supply water 7 is gradually separated into permeate water 8 and concentrated water 9. The permeate water 8 exits to the outside of the spiral separation membrane element 1 from the side surface opposite to the side from which the supply water 7 is supplied.

[0041] In this method, since the supply water 7 flows from one side surface of the spiral separation membrane element 1 to the other side surface, it necessarily has a sufficient distance in contact with the membrane. Thus, the supply water 7 is sufficiently separated into permeate water 8 and concentrated water 9. In addition, although there are various forms of separation membrane elements, they are common in that the supply water is supplied to one surface of the separation membrane and permeate water is obtained from the other surface. As the separation membrane element of the present embodiment, in addition to the spiral type, various shaped separation membrane elements using flat membranes such as plate-and-frame type and flat membrane integrated type can be adopted according to the use and purpose.

[0042] <Supply-side flow path>

[0043] (Supply-side flow path member)

[0044] In the separation membrane element, in order to suppress membrane surface concentration polarization, it is important to generate a vortex (flow) of supply water on the membrane surface behind the fibrous material. This is because the rise in salt concentration is suppressed by reducing the retention site.

[0045] Therefore, the supply-side flow path member of the present embodiment is characterized in that, as Figure 2 shown, it is a net shape formed by the three-dimensional intersection of a plurality of fibrous rows X composed of fibrous materials 21 (fibrous material A) arranged in one direction and a plurality of fibrous rows Y composed of fibrous materials 22 (fibrous material B) arranged in a direction different from the fibrous row X, and the wire diameter of the fibrous materials other than the intersection part of the supply-side flow path member is smaller than the wire diameter of the intersection part.

[0046] In addition, it is characterized in that, in the cross-section of the fibrous material 21 or 22 in an arbitrary plane 10 parallel to the flow direction of the supply water and not passing through the intersection part and perpendicular to the plane direction of the supply-side flow path member, as Figure 3 shown, when the point on the outer periphery of the cross-section where the distance between the cross-section of the fibrous material 21 and 22 other than at least some of the intersection parts and the separation membrane is the smallest is set as P, the point on the outer periphery of the cross-section where the distance is the largest on the downstream side of the supply water flow and on the same side as the distance from the separation membrane as point P is set as Q, the distance between point P and the separation membrane is set as L p and the distance between point Q and the separation membrane is set as L q and the elevation angle from point P to point Q is set as θ [°], in more than 50% of the parts of the fibrous materials other than the intersection part of the supply-side flow path member, the relationship of θ × (1 - L p / L q ) 2 > 15 is satisfied.

[0047] Generally, in the case of a pipe diameter with an expansion angle From D 1 To D 2 The expansion loss coefficient of the fluid flowing in a gradually changing circular tube, according to "Introduction to Fluid Mechanics for Learning by Practice, 2nd Edition" (2018), in the range of, is proportional to proportional.

[0048] Empirically in this application, the range of is not particularly limited and is approximately proportional to proportional. The larger the expansion loss coefficient, the more the flow is promoted to peel off from the membrane surface, and it is easy to form vortices on the membrane surface behind the fibrous material. That is, the low-speed region on the membrane surface is reduced, and concentration polarization can be suppressed. Since (1 - L p / L q ) 2 ≤1, so if θ ≤ 15°, then it becomes θ × (1 - L p / L q ) 2 ≤ 15, so the above relationship is no longer satisfied.

[0049] On the other hand, if θ > 15°, then the value of L p / L q determines whether the above relationship is satisfied in the rate determination. In order to easily form vortices on the membrane surface behind the fibrous material, the value of θ is preferably 20° or more, more preferably 45° or more.

[0050] In addition, it is preferable to satisfy the relationship of θ × (1 - L p / L q ) 2 > 20 and θ > 43°, and more preferably to satisfy the relationship of θ × (1 - L p / L q ) 2 > 24 and θ > 46°. It is easier to form vortices on the membrane surface behind the fibrous material, and a higher effect of suppressing concentration polarization can be obtained, and excellent water production and removal rate can be obtained.

[0051] Since in order to suppress the decrease in the permeate water volume due to the pressure loss, it is preferable that the cross-sectional peripheral surface of the fibrous material on the side closer to the center line of the supply-side flow path has no notch, so it is characterized in that if the ratio of the area of the aforementioned cut surface to the area of the figure formed by the outer circumference l p and the line segment l q ' is set as α, the outer circumference l p is the outer circumference on the side closer to the separation membrane surface in the outer circumference connecting point P and point Q in the aforementioned cut surface, and the line segment l q ' is the outer circumference on the side farther from the separation membrane surface lq For the line segments of the convex hull, α ≥ 70%. More preferably, α ≥ 90%. In addition, in this specification, the so-called "line segments of the convex hull" are the outer peripheries of the figures that cover the given shape without depressions. Specifically, as Figure 4 shown, when, in the outer periphery l q , for any point R where an external tangent can be drawn, and when the aforementioned external tangent intersects the aforementioned outer periphery at point S in addition to point R, if the figure formed by the line segment RS and the aforementioned outer periphery is set as A, the non-overlapping part of the outer periphery of the union of As obtained by performing this operation for all points R with the outer periphery l p is taken as the line segment l q '.

[0052] (Configuration of the supply-side flow path member)

[0053] The fibrous materials 21 and 22 constituting the supply-side flow path member are preferably non-parallel (obliquely intersecting) with respect to the water collecting pipe. By having the fibrous materials obliquely intersect the water collecting pipe, the increase in the membrane surface salt concentration on the separation membrane surface near the fibrous materials is suppressed, and concentration polarization can be suppressed, which is preferable.

[0054] (Thickness of the supply-side flow path member)

[0055] The thickness D of the supply-side flow path member C is the value obtained by observing the longitudinal section parallel to the fibrous row and measuring the thickness of the thickest part. In this embodiment, since the intersection part is composed of fibers with a larger diameter than those outside the intersection part, the thickness of the supply-side flow path member is synonymous with the thickness of the intersection part.

[0056] In this embodiment, the average thickness of the supply-side flow path member is preferably 0.30 mm or more and 4.0 mm or less, more preferably 0.45 mm or more and 2.0 mm or less. If the average thickness of the supply-side flow path member is within this range, the pressure loss will not be excessive, and a sufficient supply-side flow path can be ensured where substances such as dirt that can accumulate on the membrane surface and the supply-side flow path member are difficult to block, suppressing the blockage of the supply-side flow path caused by dirt such as impurities and microorganisms in the supply water, and enabling the separation membrane element to operate continuously, stably, and for a long time without increasing the required power of the pump. If the supply-side flow path member is thinner than this range, the pressure loss will increase, or it will become a cause for easy progress of fouling. If the supply-side flow path member is thicker than this range, the area of the separation membrane that can be mounted on the separation membrane element with a determined outer diameter will be extremely reduced, and the separation membrane element will no longer exhibit sufficient water permeability.

[0057] In addition, a commercially available microscope or X-ray CT measurement device can be used to measure the thickness of the supply-side flow path component. By observing the longitudinal section parallel to the fibrous array and measuring the distance, it can be obtained. Using the measurement mode, the thickness of the intersection part or the supply-side flow path component can be measured at any 30 locations, and the average value thereof can be set.

[0058] In addition, the dispersion of the thickness of the supply-side flow path component is preferably 0.85 times or more and 1.15 times or less of the average thickness of the supply-side flow path component. If the dispersion of the thickness of the supply-side flow path component is within this range, since the supply water can be uniformly supplied to the separation membrane element, the performance of the separation membrane can be uniformly exhibited.

[0059] (Distance between the supply-side flow path component and the separation membrane)

[0060] The distance L between the supply-side flow path component and the separation membrane P means that as shown in Figure 2 , when the supply-side flow path component is cut at 10 arbitrary planes in a plane parallel to the flow direction of the supply water and perpendicular to the plane direction of the supply-side flow path component without passing through the intersection part, the gap between the fibrous material and the separation membrane when observed from a direction perpendicular to the cut surface. At this time, the distance L P is 15% or less of the thickness of the supply-side flow path.

[0061] In addition, the distance L P is preferably 10% or less of the thickness of the supply-side flow path, more preferably 2% or more and 8% or less, and even more preferably 5% or more and 7% or less. If the distance L P is within this range, a swirling flow can be formed on the membrane surface with good efficiency, and salt concentration polarization on the membrane surface can be suppressed.

[0062] The distance L P is measured by directly observing and measuring the separation membrane element using X-ray CT. At least 10 parts of an arbitrary plane parallel to the flow direction of the supply water and not passing through the intersection part P are cut out, and the distance L P is measured in each plane, and the average value thereof is obtained.

[0063] (Distance between the supply-side flow path component and the center line of the supply-side flow path)

[0064] Figure 5 is a view observed from the cross-sectional direction of the fibrous material 21 cut at 10 planes in Figure 2 , but the distance between the supply-side flow path component and the center line of the supply-side flow path is represented by W 2 - W 1 / 2, and the W 2 - W 1 / 2 is obtained from W 1The distance W between the straight line that bisects and is parallel to the flow direction of the supply water and the center line 11 of the supply-side flow path 2 Subtracting half of W 1 The obtained length. The so-called center line of the supply-side flow path is a straight line that bisects the distance between the separation membranes and is parallel to the flow direction of the supply water. By setting it as W 2 -W 1 / 2≥0, that is, there are no fibrous substances on the center line 11 of the supply-side flow path, which can suppress the pressure loss of the supply water and is preferable. More preferably, W 2 -W 1 / 2>0.

[0065] (Intersection part interval)

[0066] In the present embodiment, Figure 2 The intersection part interval (intersection part period) c of the supply-side flow path member 2 in the direction perpendicular to the supply water flow direction (raw water flow direction) shown is preferably in the range of 3 mm or more and 5 mm or less, and more preferably in the range of 3.5 mm or more and 4.5 mm or less. If the intersection part interval c of the supply-side flow path member in the direction perpendicular to the supply water flow direction is within this range, the phenomenon that the separation membrane falls into the gap part of the supply-side flow path member can be suppressed during the production of the separation membrane element, and in particular, the flow path of the supply water inflow end face part can be stably formed.

[0067] In addition, the intersection part interval d of the supply-side flow path member in the direction parallel to the supply water flow direction is preferably in the range of 5 times or more and 10 times or less of the thickness D of the supply-side flow path member C More preferably, it is in the range of 5 times or more and 7 times or less or 8 times or more and 10 times or less. If the intersection part interval d of the supply-side flow path member in the direction parallel to the supply water flow direction is within this range, since the balance between the turbulent intensity of the supply water and the pressure loss can be taken into account, the desalination rate and water production performance of the separation membrane element can be improved. If d is 5 times or more and 7 times or less of D C , the turbulent intensity of the supply water becomes particularly high, and if it is 8 times or more and 10 times or less, the pressure loss can be particularly reduced. The intersection part interval d can be appropriately selected according to the characteristics required in the application.

[0068] As a method for measuring the intersection part interval, the supply-side flow path member can be observed from the upper part in the thickness direction (that is, the plane of the supply-side flow path member), and the distance can be measured, for example, by a microscope.

[0069] (Angle between supply water flow direction and fibrous substances)

[0070] When observing the supply-side flow path member from a planar view, although the turbulence intensity increases as the angle between the supply water flow direction (i.e., the length direction of the header pipe) and the fibrous material increases, there is a tendency for the pressure loss to increase. Therefore, the aforementioned angle is preferably 10° or more and 50° or less, more preferably 20° or more and 45° or less.

[0071] (Cross-sectional shape of the fiber)

[0072] Figure 6 (a) to Figure 6 (e) are plan views taken along a plane parallel to the supply water flow direction and perpendicular to the planar direction of the aforementioned supply-side flow path member, showing examples of the supply-side flow path member of the present embodiment. The supply water flow direction is set from left to right, but for symmetric shapes ( Figure 6 (a) to Figure 6 (c)), it does not matter if the supply water flow direction is from right to left. As the cross-sectional shape at the cross-section perpendicular to the length direction of the fiber of the supply-side flow path member, it is required that θ > 15°. For example, shapes based on a perfect circle, a vertical ellipse, and a spindle shape as shown Figure 6 can be cited. In addition, as shown in Figure 6 (d), by having a protrusion at the rear in the supply water flow direction, the peeling of the flow from the membrane surface is further promoted, and it is easy to form a vortex on the membrane surface behind the fibrous material. In addition, in order to make it difficult to generate a stagnant area between the separation membrane surface, it is preferable that the inclination of the tangent at all points on the outer periphery l p is always -20° or more with respect to the separation membrane.

[0073] Figure 7 (f) to Figure 7 (k), Figure 8 (l) to Figure 8 (o) are plan views taken along a plane parallel to the supply water flow direction and perpendicular to the planar direction of the supply-side flow path member, showing examples of supply-side flow path members other than the present embodiment. The supply water flow direction is set from left to right, but for symmetric shapes ( Figure 7 (f), Figure 7 (g), Figure 8 (l)), it does not matter if the supply water flow direction is from right to left. Figure 7 (f) to Figure 7 (h), Figure 7 (i), Figure 7 (k) have the same cross-sectional shape as Figure 6 (a) to Figure 6 (e), but since L p / L q becomes larger, it becomes θ × (1 - L p / L q ) 2The case where it is ≤15. On the other hand, as Figure 8 (l) shows, in the horizontal elliptical shape where θ≤15°, regardless of the value of L p / L q , it becomes θ×(1-L p / L q ), 2 ≤15, so it deviates from the scope of this embodiment.

[0074] (Raw material)

[0075] The raw material of the supply-side flow path member is not particularly limited, but from the viewpoint of formability, a thermoplastic resin is preferred. In particular, polyethylene and polypropylene are difficult to damage the surface of the separation membrane and are relatively inexpensive, so they are preferred. In addition, for the supply-side flow path member, the fibrous materials 21 and 22 may be formed of the same raw material or different raw materials.

[0076] (Manufacturing method)

[0077] The formation of the net-shaped supply-side flow path member generally involves rotating two spinnerets with many holes arranged on the inner and outer circumferences in opposite directions while supplying molten resin from an extruder. When the resin exits the spinneret or immediately after that, the lines exiting the inner and outer spinnerets cross in a molten state and melt to form a net structure. At this stage, it takes the shape of a net-like cylinder. Then, after the cylindrical net is cooled and solidified to determine the thickness, wire diameter, and intersection interval, it is cut and pulled as a sheet-like net. The size and shape of the holes in the spinneret determine the thickness of the supply-side flow path member and the shape of the fibrous material. Based on the interval between the holes in the spinneret and the balance between the line speed and the conveying speed of the spinneret, the intersection interval and the angle between the supply water flow direction and the fibrous material are determined. In addition, by appropriately heating and stretching the sheet-like net while maintaining the wire diameter of the intersections, it is possible to make only the wire diameter between the intersections thinner while maintaining the wire diameter of the intersections. The ratio of the wire diameter between intersections and the wire diameter change within one fibrous material can be controlled by the raw material, heating temperature, stretching direction, and stretching ratio.

[0078] In order to manufacture a supply-side flow path member as in this embodiment where there are thick and thin portions in the fibrous material 21 or the fibrous material 22 and the thin portion of the fibrous material 21 or the fibrous material 22 forms an intersection with the other fibrous material, the following method is adopted: while rotating two spinnerets with many holes arranged on the inner and outer sides in opposite directions, resin is supplied at a specified resin ejection pressure to form a cylindrical net with a net structure. After it is cooled and solidified, longitudinal stretching and then transverse stretching are sequentially performed in a heating furnace.

[0079] In addition, the method for manufacturing the net of the present embodiment is not limited to these, and methods such as embossing, stamping, and pressing can also be used to compress and deform the fibrous material between the intersection parts, a method of casting and removing molten resin in a mold, or a 3D printer can be used for manufacturing.

[0080] <Through-side flow path>

[0081] (Through-side flow path member)

[0082] In the envelope-shaped film 5, the separation membranes 3 are superposed with their through-sides facing each other, and a through-side flow path member 4 is disposed between the separation membranes 3, and a through-side flow path is formed by the through-side flow path member 4. The material of the through-side flow path member is not limited, and tricot woven fabric, non-woven fabric, a porous sheet with protrusions fixed thereto, a film formed with concavo-convex shapes and perforated, or concavo-convex non-woven fabric can be used. In addition, protrusions that function as the through-side flow path member can be fixed to the through-side of the separation membrane.

[0083] <Formation of separation membrane blades>

[0084] The separation membrane blades can be formed by folding the separation membrane with the supply-side surface facing inward, or by superposing two separate separation membranes with their supply-side surfaces facing each other and sealing the periphery of the separation membranes.

[0085] In addition, as a method for performing "sealing", adhesion by an adhesive or hot melt, fusion bonding by heating or laser, and a method of sandwiching a rubber sheet can be cited. Sealing by adhesion is particularly preferred because it is the simplest and has a relatively high effect.

[0086] <Utilization of separation membrane elements>

[0087] The separation membrane elements can also be connected in series or in parallel and housed in a pressure vessel to be used as a separation membrane module.

[0088] In addition, the above-mentioned separation membrane elements and separation membrane modules can be combined with a pump for supplying fluid to them, a device for pre-treating the fluid, etc. to constitute a fluid separation device. By using this separation device, for example, supplied water can be separated into permeated water such as drinking water and concentrated water that does not pass through the membrane, and water meeting the purpose can be obtained.

[0089] If the operating pressure of the fluid separation device is considered, a higher operating pressure results in an increased removal rate, but the energy required for operation also increases. In addition, considering the retention of the supply flow path and the permeate flow path of the separation membrane element, the operating pressure when the supplied water permeates through the separation membrane module is preferably 0.2 MPa or more and 6 MPa or less.

[0090] If the supply water temperature becomes higher, the salt rejection rate decreases, but if it becomes lower, the membrane permeation flux also decreases. Therefore, it is preferably 5°C or higher and 45°C or lower.

[0091] In addition, when the pH of the raw water is in the neutral range, even if the raw water is a liquid with a high salt concentration such as seawater, the generation of scale such as magnesium is suppressed, and in addition, the deterioration of the membrane is also suppressed.

[0092] (Supply water)

[0093] The supply water to the separation membrane element of the present embodiment is not particularly limited, and it may be pre-treated tap water, or water with a large amount of impurities in the solution such as seawater, brackish water, and sewage. For example, when used for water treatment, as the raw water (supply water), liquid mixtures containing 500 mg / L or more and 100 g / L or less of TDS (Total Dissolved Solids) such as seawater, brackish water, and drainage can be cited. Generally, TDS refers to the total dissolved solid component amount, which is expressed as "mass ÷ volume", but there are also cases where 1 L is regarded as 1 kg and it is expressed as "mass ratio". According to the definition, the solution filtered by a 0.45 μm filter can be evaporated at a temperature of 39.5 to 40.5°C and calculated based on the weight of the residue, but it is more simply converted from the practical salinity (S).

[0094] Examples

[0095] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by these examples at all.

[0096] (Measurement of the thickness of the supply-side flow path member)

[0097] Using a shape measurement system (for example, the high-precision shape measurement system "KS-1100" manufactured by Keyence Corporation), the longitudinal section parallel to the fibrous column of the supply-side flow path member was observed at a magnification of 20 times, and the thickness of the supply-side flow path member was measured at 30 locations, and its average value was calculated.

[0098] (Cross-sectional wire diameter of the supply-side flow path member)

[0099] The supply-side flow path member was cut at 10 arbitrary planes parallel to the flow direction of the supply water and not passing through the intersection part, and observed from a direction perpendicular to the cut surface using a shape measurement system (for example, the high-precision shape measurement system "KS-1100") to perform the measurement of W 1 measurement.

[0100] At least 10 parts were cut out from 10 arbitrary planes, and W 1 was measured at each plane, and the average value thereof was obtained.

[0101] (Distance between the supply-side flow path component and the center line of the supply-side flow path)

[0102] The separation membrane element is cut in a direction perpendicular to the length direction of the header pipe from a position 6 inches from the end to a position 12 inches from the end to cut out a cylindrical specimen with a length of 6 inches. To prevent the flow path structure from collapsing, an adhesive is applied to the entire surface from both sides of the cut surface of the element, and the adhesive is slightly impregnated from the end of the element. The cylindrical specimen is cut into a columnar body in the shape of a sector with a central angle of 60 degrees at the bottom surface to obtain an observation specimen. Then, it is dried in a vacuum oven set at 40 °C until there is no longer any change in the weight of the fan-shaped specimen. Using a GE X-ray CT measurement device Phoenix v|tome|x m300, it is scanned under the conditions of a tube current of 100 μA, a tube voltage of 150 kV, and a resolution of 19.8 μm to obtain a 3D image. Then, it is analyzed using VOLUMEGRAPHICS VGSTUDIO MAX to perform the measurement of W 2 . At least 10 parts are cut out from an arbitrary plane 10, and W 2 is measured on each plane, and the average value is obtained as their average value.

[0103] (Distance between the supply-side flow path component and the separation membrane, θ, α)

[0104] The separation membrane element is cut in a direction perpendicular to the length direction of the header pipe from a position 6 inches from the end to a position 12 inches from the end to cut out a cylindrical specimen with a length of 6 inches. To prevent the flow path structure from collapsing, an adhesive is applied to the entire surface from both sides of the cut surface of the element, and the adhesive is slightly impregnated from the end of the element. The cylindrical specimen is cut into a columnar body in the shape of a sector with a central angle of 60 degrees at the bottom surface to obtain an observation specimen. Then, it is dried in a vacuum oven set at 40 °C until there is no longer any change in the weight of the fan-shaped specimen. Using a GE X-ray CT measurement device Phoenix v|tome|x m300, it is scanned under the conditions of a tube current of 100 μA, a tube voltage of 150 kV, and a resolution of 19.8 μm to obtain a 3D image. Then, it is analyzed using VOLUMEGRAPHICS VGSTUDIO MAX to perform the measurement of the distance L p , L q and the elevation angle θ from point P to point Q. At least 10 parts are cut out from an arbitrary plane 10, and the distance L p , L qThe elevation angle θ is obtained as their average value. In addition, for the cross-sectional view of the obtained fibrous material, α is measured using ImageJ ver.1.45 (development source: Wayne Rasband, National Institutes of Health, NIH) and obtained as the average value of 10 parts.

[0105] (Intersection part interval)

[0106] Using a shape measurement system (e.g., Keyence Corporation's high-precision shape measurement system "KS-1100"), the mesh specimen is observed from the upper part in the thickness direction at a magnification of 20 times. For the intersection part interval of the supply-side flow path member in the direction perpendicular to the supply water flow direction and the intersection part interval of the supply-side flow path member in the direction parallel to the supply water flow direction, 30 arbitrary intersection part intervals are measured, and their average value is calculated.

[0107] <Example>

[0108] (Manufacture of supply-side flow path member S)

[0109] Using polypropylene as the material, while rotating two spinnerets with many small holes on the inner and outer sides in opposite directions, the molten resin is supplied from the extruder at a specified ejection pressure to form a cylindrical net with a mesh structure. After cooling and solidifying it, longitudinal stretching and then transverse stretching are sequentially performed in a heating furnace to manufacture the supply-side flow path member shown in Table 1. In addition, the shape, size of the holes in the spinneret, the ejection pressure of the molten resin from the extruder, the pulling speed, the longitudinal stretching / transverse stretching ratio, and the temperature in the heating furnace are changed to control the structure so that it finally becomes the shape of the supply-side flow path member in Table 1.

[0110] (Manufacture of supply-side flow path member T)

[0111] Using polypropylene as the material, while rotating two spinnerets with many holes on the inner and outer sides in opposite directions, the molten resin is supplied from the extruder to form a cylindrical net with a mesh structure, and a net with a cylindrical fiber shape is manufactured. In addition, the shape, size of the holes in the spinneret, the ejection pressure of the molten resin from the extruder, the pulling speed are changed to control the structure so that it finally becomes the shape of the supply-side flow path member in Table 3.

[0112] (Manufacture of separation membrane U)

[0113] In a non-woven fabric composed of polyethylene terephthalate fibers (fiber fineness: 1 dtex, thickness: about 90 μm, air permeability: 1 cc / cm 2 / sec, density 0.80 g / cm 3) A 16.0 mass% DMF solution of polysulfone was cast at a thickness of 180 μm at room temperature (25 °C), immediately immersed in pure water and left for 5 minutes, and then immersed in warm water at 80 °C for 1 minute, thereby producing a roll of a porous support layer (thickness 130 μm) composed of a fiber-reinforced polysulfone support membrane.

[0114] Then, the surface of the polysulfone layer of the porous support membrane was immersed in an aqueous solution containing 1.5 mass% of m-PDA and 1.0 mass% of ε-caprolactam for two minutes, and then slowly pulled up in the vertical direction. Furthermore, the excess aqueous solution was removed from the surface of the support membrane by blowing nitrogen from an air nozzle.

[0115] Then, an n-decane solution containing 0.08 mass% of trimesoyl chloride was applied to completely wet the surface of the membrane, and then left standing for 1 minute. Then, the excess solution was removed from the membrane by air blowing, and the membrane was washed with hot water at 80 °C for 1 minute to obtain a composite separation membrane roll of separation membrane U.

[0116] (Fabrication of Separation Membrane V)

[0117] On a non-woven fabric composed of polyethylene terephthalate fibers (fineness: 1 dtex, thickness: about 90 μm, air permeability: 1 cc / cm 2 / sec, density 0.80 g / cm 3 ) A 16.0 mass% DMF solution of polysulfone was cast at a thickness of 180 μm at room temperature (25 °C), immediately immersed in pure water and left for 5 minutes, and then immersed in warm water at 80 °C for 1 minute, thereby producing a roll of a porous support layer (thickness 130 μm) composed of a fiber-reinforced polysulfone support membrane.

[0118] Then, the surface of the polysulfone layer of the porous support membrane was immersed in an aqueous solution containing 3.0 mass% of m-PDA and 2.0 mass% of ε-caprolactam for two minutes, and then slowly pulled up in the vertical direction. Furthermore, the excess aqueous solution was removed from the surface of the support membrane by blowing nitrogen from an air nozzle.

[0119] Then, an n-decane solution containing 0.15 mass% of trimesoyl chloride was applied to completely wet the surface of the membrane, and then left standing for 1 minute. Then, the excess solution was removed from the membrane by air blowing, and the membrane was washed with hot water at 80 °C for 1 minute to obtain a composite separation membrane roll of separation membrane V.

[0120] (Fabrication of Spiral Separation Membrane Element)

[0121] The separation membrane U or V was folded and cut so that the effective area in the separation membrane element became 8 m 2 , and a polypropylene mesh (thickness: 0.8 mm) shown in Table 1 was sandwiched as a feed water side flow path member to produce a separation membrane blade.

[0122] On the permeate side of the obtained separation membrane blade, the tricot warp knitting fabric shown in Table 1 (thickness: 0.26 mm) is laminated as a permeate side flow path member, a blade adhesive is applied, and it is wound around a PVC (polyvinyl chloride) header pipe (width: 1016 mm, diameter: 19 mm, number of holes 23 × linear 1 row) in a spiral shape. After fixing the outer peripheral surface of the wound body with tape, edge cutting at both ends and end plate installation are carried out to fabricate a 4-inch diameter separation membrane element in which feed water is supplied from one side and concentrated water is discharged.

[0123] (Water production rate)

[0124] After operating for two hours under the following conditions, sampling is carried out for 1 minute, and the water permeation amount (gallons) per day is expressed as the water production rate (GPD (gallons per day)).

[0125] (Condition A)

[0126] The separation membrane element made using separation membrane U is installed in a pressure vessel, and an aqueous NaCl solution with a temperature of 25°C, a concentration of 2000 mg / L, and a pH of 7.0 is used as the feed water, and the operating pressure is set to 1.55 MPa and the recovery rate is set to 15%.

[0127] (Condition B)

[0128] The separation membrane element made using separation membrane V is installed in a pressure vessel, and an aqueous NaCl solution with a temperature of 25°C, a concentration of 32000 mg / L, and a pH of 7.0 is used as the feed water, and the operating pressure is set to 5.52 MPa and the recovery rate is set to 8%.

[0129] (Removal rate (TDS removal rate))

[0130] For the feed water used during the 1-minute operation and the sampled permeate water in the measurement of the water production rate, the TDS concentration is obtained by conductivity measurement, and the TDS removal rate is calculated according to the following formula.

[0131] TDS removal rate (%) = 100 × {1 - (TDS concentration in permeate water / TDS concentration in feed water)}

[0132] (Element differential pressure)

[0133] Connect the upstream side (feed water side) and the downstream side (concentrate water side) of the cylindrical pressure vessel filled with the separation membrane element through piping using a differential pressure gauge manufactured by Nagano Keiki Co., Ltd. (Model DG16), and measure the differential pressure across the element during operation. The operating conditions are set as a feed water flow rate of 9 L / minute, an operating pressure of 1.0 MPa, and reverse osmosis membrane-treated water is used in the feed water. In addition, after the air bubbles inside the element are discharged, close the faucet of the permeate water piping, and operate under a state where membrane filtration is substantially not performed, that is, a state where the entire amount of feed water is discharged as concentrate water, and measure the differential pressure (kPa) across the element.

[0134] (Example 1)

[0135] Load the fabricated separation membrane element into the pressure vessel and evaluate it under the above conditions. The results are as shown in Table 1. Additionally, θ, L p 、L q 、W 1 、W 2 、α, d have the same values in the fibrous materials 21 and 22. Additionally, the value of D c is equal to the thickness of the feed side flow path.

[0136] (Examples 2 - 13)

[0137] Except for making the feed side flow path components as shown in Table 1 and Table 2, all are set to be the same as in Example 1 to fabricate the separation membrane element. Additionally, θ, L p 、L q 、W 1 、W 2 、α, d have the same values in the fibrous materials 21 and 22. Additionally, the value of D c is equal to the thickness of the feed side flow path.

[0138] Load the separation membrane element into the pressure vessel and evaluate each performance under the same conditions as in Example 1. The results are as shown in Table 1 and Table 2.

[0139] <Comparative Example>

[0140] (Comparative Examples 1 - 6)

[0141] Except for making the feed side flow path components as shown in Table 3, all are set to be the same as in Example 1 to fabricate the separation membrane element. Additionally, θ, L p 、L q 、W 1 、W 2 、α, d have the same values in the fibrous materials 21 and 22. Additionally, the value of D c is equal to the thickness of the feed side flow path.

[0142] Load the separation membrane element into the pressure vessel and evaluate each performance under the above conditions. The results are as shown in Table 3.

[0143] [Table 1]

[0144]

[0145] [Table 2]

[0146]

[0147] [Table 3]

[0148]

[0149] As is clear from the results shown in Tables 1 to 3, the separation membrane elements of Examples 1 to 13 have excellent separation performance.

[0150] On the other hand, in Comparative Example 1, since the cross-sectional shape of the fibrous material is different from that of Example 3, it becomes θ×(1−L p / L q ) 2 ≤15, so the water production rate and rejection rate decrease compared with Example 3. In Comparative Example 2, since the wire diameter of the fibrous material other than the intersection part of the supply-side flow path member is equal to the wire diameter of the intersection part compared with Example 3 (L p =0), the water production rate and rejection rate decrease compared with Example 3. In Comparative Examples 3 and 5, since compared with Example 3, the proportion of fibrous materials satisfying θ×(1−L p / L q ) 2 >15 and α≥70% and L p / D C ≤0.15 is less than 50%, the water production rate and rejection rate decrease compared with Example 3. In Comparative Example 4, since α is less than 70% compared with Example 3, the pressure loss increases, and the water production rate and rejection rate decrease compared with Example 3. In Comparative Example 6, since the distance L p is larger than 15% of the thickness D C , the water production rate and rejection rate decrease compared with Example 3.

[0151] As described above, various embodiments have been described, but the present invention is of course not limited to this example. Obviously, those skilled in the art can conceive of various modification examples or correction examples within the scope described in the claims, and it should be understood that these also of course belong to the technical scope of the present invention. In addition, the constituent elements in the above embodiments can be arbitrarily combined without departing from the gist of the invention.

[0152] In addition, this application is based on a Japanese patent application (Japanese Patent Application No. 2022-174183) filed on October 31, 2022, the content of which is incorporated herein by reference.

[0153] Industrial Applicability

[0154] The membrane element of the present invention can be particularly suitable for desalination of brackish water and seawater and effective utilization as an RO water purifier.

[0155] Explanation of Reference Numerals

[0156] 1 Spiral separation membrane element

[0157] 2 Supply-side flow path member

[0158] 21 Fiber-like material (fiber-like material A)

[0159] 22 Fiber-like material (fiber-like material B)

[0160] 3 Separation membrane

[0161] 4 Permeate-side flow path member

[0162] 5 Envelope-shaped membrane

[0163] 6 Header pipe

[0164] 7 Feed water

[0165] 8 Permeate water

[0166] 9 Concentrated water

[0167] 10 Any plane in the plane that is parallel to the flow direction of the feed water and perpendicular to the plane direction of the supply-side flow path member and does not pass through the intersection portion P

[0168] 11 Supply-side flow path center line

[0169] c Intersection portion interval of the supply-side flow path member in the direction perpendicular to the feed water flow direction

[0170] d Intersection portion interval of the supply-side flow path member in the direction parallel to the feed water flow direction

[0171] D C Intersection portion thickness

[0172] L p Minimum value of the distance between the fiber-like material 21 or 22 and the separation membrane on the side close to the fiber-like material in the plane 10

[0173] L q Maximum value of the distance between the fiber-like material 21 or 22 and the separation membrane on the side close to the fiber-like material in the plane 10

[0174] A point on the outer periphery of the fibrous material 21 or 22 in the plane 10 where the distance between the fibrous material and the separation membrane on the side close to the fibrous material is minimized

[0175] A point on the outer periphery of the fibrous material 21 or 22 on the downstream side of the water supply with respect to point P, where the distance between the fibrous material and the separation membrane on the side close to the fibrous material is maximized

[0176] The elevation angle from point P to point Q

[0177] The line width in the direction perpendicular to the water supply flow direction in the cross-section of the fibrous material 21 or 22 in a plane parallel to the water supply flow direction and perpendicular to the plane direction of the supply-side flow path member

[0178] The distance between a straight line parallel to the water supply flow direction passing through the center in the thickness direction of the cross-section of the fibrous material 21 or 22 in a plane parallel to the water supply flow direction and perpendicular to the plane direction of the supply-side flow path member and a straight line parallel to the water supply flow direction passing through the center in the thickness direction of the supply-side flow path in the cross-section of the fibrous material 21 or 22

[0179] l p The outer periphery on the side closer to the separation membrane surface in the outer periphery connecting point P and point Q in the cross-section

[0180] l q The outer periphery on the side farther from the separation membrane surface in the outer periphery connecting point P and point Q in the cross-section

[0181] l q ’ The outer periphery l q The line segment of the convex hull

[0182] α The ratio of the area of the cross-section to the area of the figure formed by the outer periphery l p and the line segment l q ’

Claims

1. A separation membrane element, comprising a header pipe, a separation membrane having a supply side surface and a permeate side surface, a supply side flow path member disposed on the supply side surface, and a permeate side flow path member disposed on the permeate side surface; the separation membrane, the supply side flow path member, and the permeate side flow path member are wound around the header pipe; the separation membrane element is characterized in that the supply side flow path member is a net shape formed by a plurality of fibrous rows X composed of fibrous material A arranged in one direction and a plurality of fibrous rows Y composed of fibrous material B arranged in a direction different from the fibrous rows X intersecting three-dimensionally to form intersections; the wire diameter of the fibrous material other than the intersection portion of the supply side flow path member is smaller than the wire diameter of the intersection portion; When a point P on the outer periphery of the cut surface where the distance between the cut surface other than the intersection portion of at least one of the fibrous materials A and B and the separation membrane is minimized in a plane parallel to the flow direction of the supply water and perpendicular to the plane direction of the supply-side flow path member is set, a point Q on the outer periphery of the cut surface where the distance is maximized on the downstream side of the supply water flow relative to P and on the same side as the distance from the separation membrane is set, and the distance between P and the separation membrane is set to L p , the distance between Q and the separation membrane is set to L q , when the elevation angle from P to Q is set to θ [°], in more than 50% of the portion of the fibrous material other than the intersection portion of the supply-side flow path member, the relationship θ×(1-L p / L q ) 2 >15 is satisfied, and if the ratio of the area of the cut surface to the area of the figure formed by the outer periphery l p and the line segment l q ’ is set to α, the outer periphery l p is the outer periphery on the side closer to the separation membrane surface in the outer periphery connecting P and Q in the cut surface, the line segment l q ’ is the line segment that bulges the outer periphery l q on the side farther from the separation membrane surface, then α≥70%, and L p is 15% or less of the thickness D C of the supply-side flow path.

2. The separation membrane element according to claim 1, characterized in that Satisfy the relationship of θ×(1-L p / L q ) 2 > 20 and θ > 43°.

3. The separation membrane element according to claim 1, characterized in that Satisfy the relationship of θ×(1-L p / L q ) 2 > 24 and θ > 46°.

4. The separation membrane element according to any one of claims 1 to 3, characterized in that When, in the foregoing cut surface, the maximum width in the thickness direction of the foregoing supply-side flow path member is set to W 1 and the distance between a straight line passing through the center in the thickness direction of the foregoing cut surface and parallel to the flow direction of the foregoing supply water and a straight line passing through the center in the thickness direction of the foregoing supply-side flow path and parallel to the flow direction of the foregoing supply water is set to W 2 then the relationship W 2 −W 1 / 2 ≥ 0 is satisfied.

5. The separation membrane element according to any one of claims 1 to 4, characterized in that a protrusion is provided at the rear portion of the cut surface in the flow direction of the supply water.

6. The separation membrane element according to any one of claims 1 to 5, characterized in that α≥90%.

7. The separation membrane element according to any one of claims 1 to 6, characterized in that the supply side flow path member is an obliquely crossed net.

8. The separation membrane element according to any one of claims 1 to 7, characterized in that the intersection interval of the supply side flow path member in the flow direction of the supply water is 5 times or more and 10 times or less the thickness of the supply side flow path member.

9. The separation membrane element according to any one of claims 1 to 7, characterized in that the intersection interval of the supply side flow path member in the flow direction of the supply water is 5 times or more and 7 times or less the thickness of the supply side flow path member.

10. The separation membrane element according to any one of claims 1 to 7, characterized in that the intersection interval of the supply side flow path member in the flow direction of the supply water is 8 times or more and 10 times or less the thickness of the supply side flow path member.

11. A method for filtering a liquid, characterized in that the separation membrane element according to any one of claims 1 to 10 is used.

12. A liquid separation device, characterized in that the separation membrane element according to any one of claims 1 to 10 is used.

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