JPH10235165A - Operation method of spiral-shaped membrane element and treatment system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for operating a spiral-shaped membrane element capable of being reduced in cost and capable of obtaining stable transmitted flux over a long period of time and having high reliability and a treatment system using the same. SOLUTION: Raw water is supplied to a flocculation reaction tank 100 and a flocculant is added to raw water by a flocculant supply means 102 to be stirred by a stirrer 101. The raw water to which the flocculant is added is supplied to a spiral-shaped membrane element 1. The spiral-shaped membrane element 1 is constituted by winding a plurality of independent or continuous envelope-shaped membranes around the outer peripheral surface of a water gathering pipe and inserting raw water spacers into the gaps between the envelope-shaped membranes and covering the outer peripheral surface with an outer peripheral part passage material. Raw water is supplied from at least the outer peripheral part side of the spiral-shaped membrane element 1 and permeated water is taken out of the opening end of the water gathering pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating a spiral type membrane element used in a membrane separation device such as a low pressure reverse osmosis membrane separation device, an ultrafiltration device and a microfiltration device, and a treatment system using the same.

[0002]

2. Description of the Related Art A membrane separation technique is being applied as a pretreatment of a reverse osmosis membrane separation system used in seawater desalination and the like. Types of membranes used for such membrane separation include:
Although a microfiltration membrane and an ultrafiltration membrane capable of obtaining a high permeated water amount are often used, a reverse osmosis membrane capable of obtaining a high permeated water amount at an ultra-low pressure of 10 kgf / cm ² or less has recently been developed.

As a form of the membrane element used for the membrane separation, a hollow fiber membrane element is often used in view of a membrane area per unit volume (volume efficiency). However, the hollow fiber membrane element has a disadvantage that the membrane is easily broken, and if the membrane is broken, the raw water mixes with the permeated water and the separation performance is reduced.

On the other hand, there is a spiral type membrane element as a form of a membrane element capable of increasing a membrane area. This spiral type membrane element has an advantage that separation performance can be maintained and reliability is high as compared with a hollow fiber membrane element.

FIG. 7 is a partially cutaway perspective view of a conventional spiral membrane element, and FIG. 8 is an external perspective view of the conventional spiral membrane element.

[0007] As shown in FIG. 7, the spiral membrane element 21 forms an envelope-like membrane (bag-like membrane) 23 by superimposing a separation membrane 26 on both surfaces of a permeated water spacer 25 and bonding three sides thereof. Then, the opening of the envelope-shaped membrane 23 is attached to the water collecting pipe 22 composed of a perforated hollow pipe, and is formed into a net shape (net shape).
The raw water spacer 24 is spirally wound around the outer peripheral surface of the water collecting pipe 22.

The raw water spacer 24 is provided for forming a flow path through which raw water passes between the envelope membranes 23. If the thickness of the raw water spacer 24 is small, the filling efficiency of the separation membrane 26 is increased, but clogging with the suspended substance occurs. Therefore, usually, the thickness of the raw water spacer 24 is about 0.7 mm to 3.0 m.
m.

A spiral membrane element using a zigzag corrugated raw water spacer (so-called corrugated spacer) for treating raw water containing a large amount of suspended substances, such as river water, has already been known.

As shown in FIG. 8, the outer peripheral surface of the spiral-type membrane element 21 is covered with an exterior material 27 made of FRP (fiber reinforced plastic), a shrink tube, or the like.
Packing holders 28 called anti-telescopes are respectively attached to both ends.

FIG. 9 is a sectional view showing an example of a conventional method of operating a spiral type membrane element. As shown in FIG. 9, the pressure vessel (pressure-resistant vessel) 30 is composed of a cylindrical case 31 and a pair of end plates 32a and 32b. A raw water inlet 33 is formed in one end plate 32a, and the other end plate 3
A concentrated water outlet 35 is formed in 2b. A permeated water outlet 34 is provided at the center of the other end plate 32b.

A spiral type membrane element 21 having a packing 37 attached near one end of the outer peripheral surface is mounted in a cylindrical case 31, and both open ends of the cylindrical case 31 are sealed with end plates 32a and 32b, respectively. I do. One open end of the water collecting pipe 22 is fitted to the permeated water outlet 34 of the end plate 32b, and an end cap 36 is attached to the other open end.

During the operation of the spiral type membrane element 21, the raw water 51 is introduced into the first liquid chamber 38 from the raw water inlet 33 of the pressure vessel 30. As shown in FIG.
Is supplied from one end face side of the spiral membrane element 21. The raw water 51 flows in the axial direction along the raw water spacer 24, and is discharged as concentrated water 53 from the other end surface side of the spiral membrane element 21. As the raw water 51 flows along the raw water spacer 24, the permeated water 52 that has passed through the separation membrane 26 is collected along the permeated water spacer 25 by the water collecting pipe 2.
2 and discharged from the end of the water collecting pipe 22.

The permeated water 52 is taken out from the permeated water outlet 34 of the pressure vessel 30 shown in FIG. Further, the concentrated water 53 is taken out of the second liquid chamber 39 in the pressure vessel 30 through the concentrated water outlet 35 to the outside.

[0014]

In general, when the membrane element is operated, not only suspended and colloidal substances coexisting in raw water but also dissolved organic substances and the like accumulate on the membrane surface, and the filtration rate is increased. The gel material having a large resistance gradually and firmly accumulates, and the permeation flux decreases over time. Therefore, in order to remove suspended substances, colloidal substances, dissolved organic substances, and the like in raw water, pretreatment mainly by flocculation, precipitation, and sand filtration is performed.

However, such a pre-processing system requires a large installation area and is complicated to manage. Further, even if such pretreatment is performed, accumulation of suspended substances, colloidal substances, dissolved organic substances, and the like on the film surface cannot be completely prevented. Therefore, the amount of permeated water is recovered by performing chemical cleaning or the like, but the labor and cost required for the chemical cleaning or the like are problematic.

In order to remove the colloid components in the raw water, there is known a method in which an inorganic coagulant is added and raw water subjected to coagulation treatment is directly supplied to the membrane element. According to this method, the colloid component is flocculated by the flocculant. However, these flocculants are compressible, and when placed under high-pressure conditions, are densified to increase the filtration specific resistance. Decrease over time.

On the other hand, for example, in the case of a hollow fiber membrane element, backflow washing with permeated water or air is performed so as to prevent accumulation of suspended substances and colloidal substances and clogging of the membrane by a gel layer formed by dissolved organic substances. Is regularly performed.

However, in the conventional spiral membrane element 21, the outer peripheral surface of the envelope membrane 23 wound around the water collecting pipe 22 is covered with the exterior material 27. Contaminants such as suspended substances causing the jam are easily captured by the raw water spacer 24 before being discharged from the end of the membrane element 21 and are not sufficiently removed. Therefore, when the spiral membrane element 21 is used for a long time, there is a problem that the amount of permeated water decreases.

Further, a gap existing between the inner peripheral surface of the cylindrical case 31 of the pressure vessel 30 and the spiral membrane element 21 becomes a dead space S, and stagnation of the fluid (liquid pool) occurs. When the spiral type membrane element 21 is used for a long time, the fluid staying in the dead space is denatured. In particular, when the fluid is a liquid containing an organic substance, germs such as microorganisms propagate, and the germs may decompose the organic substance to generate a bad smell or decompose the separation membrane. Leads to a decrease in

Further, in the conventional spiral-type membrane element 21, raw water is supplied from one end of the spiral-type membrane element 21 and discharged from the other end.
A packing holder 28 is required to prevent the envelope-shaped film 23 wound in 2 from being deformed into a bamboo shoot shape.
Further, a pressure difference occurs between the raw water inflow side and the concentrated water outlet side due to the pressure loss due to the raw water spacer 24 and the pressure loss due to clogging, and the spiral membrane element 21 is deformed. In order to prevent this deformation, the outer peripheral surface of the envelope-like film 23 wound around the water collecting pipe 22 is covered with an exterior material 27 such as an FRP or a shrinkable tube. These increase component costs and manufacturing costs.

Further, it is necessary to obtain a sufficient film surface linear velocity in order to prevent the formation of cake due to contaminants in raw water, and for that purpose, a sufficient flow rate on the concentration side is required. If the flow rate on the concentration side is increased, the recovery rate per membrane element will be low, and the pump for supplying raw water will be large, and the system cost will be very large.

An object of the present invention is to provide a highly reliable spiral-type membrane element operating method capable of reducing costs and obtaining a stable permeation flux for a long period of time, and a processing system using the same. is there.

[0023]

Means for Solving the Problems and Effects of the Invention A method for operating a spiral type membrane element according to the first invention is a method of adding a coagulant to a stock solution and forming a plurality of independent or continuous plural pieces on the outer peripheral surface of a perforated hollow tube. A raw solution to which a flocculant has been added is supplied from the outer peripheral side and both ends of a spiral membrane element formed by winding the envelope membrane through a raw liquid flow path material, and at least one opening of a perforated hollow tube is provided. The permeate is taken out from the end.

In the method for operating a spiral-type membrane element according to the present invention, since a dissolved organic substance or the like in a stock solution is flocculated by the addition of a coagulant, a gel layer made of a gel-like substance having a large filtration specific resistance is formed on the membrane surface. Not formed on. Thereby, clogging of the membrane due to formation of the gel layer is prevented, and reduction of the permeation flux is prevented.

Further, since the outer peripheral surface and both end surfaces of the spiral type membrane element are open without being covered with the exterior material, the stock solution containing the coagulant is supplied from the outer peripheral side and both end sides of the membrane element. And the whole amount is filtered.

As described above, since the stock solution to which the coagulant is added is supplied from the outer peripheral side and both ends of the membrane element, contaminants including flocs generated by the coagulation are captured at the outer peripheral section and both ends of the membrane element. Is done. Therefore, it is possible to uniformly remove contaminants by backwashing with, for example, permeated water. As a result, a stable permeation flux can be obtained for a long period of time.

Further, according to the structure of the spiral type membrane element described above, dead space is not formed in the gap between the membrane element and the pressure vessel due to the total amount filtration.
No fluid stagnation occurs in the gap between the membrane element and the pressure vessel. Therefore, even when used for separating a fluid containing an organic substance, problems such as propagation of various germs such as microorganisms, generation of offensive odor due to decomposition of the organic substance, and decomposition of the separation membrane do not occur, and high reliability can be obtained.

Further, the undiluted solution is supplied from the outer peripheral side and both ends of the membrane element, and pressure is applied to the membrane element from all directions and no pressure that causes displacement in the axial direction is applied. The envelope-shaped film wound around the sheet does not deform into a bamboo shoot. This eliminates the need for a packing holder and an exterior material, thereby reducing parts costs and manufacturing costs. In addition, since the whole amount is filtered, a high recovery rate can be obtained without using a large pump for supplying the stock solution. Thereby, system costs and operating costs are reduced.

A method for operating a spiral type membrane element according to a second aspect of the present invention is a method of operating a spiral type membrane element, wherein a coagulant is added to a stock solution, and a plurality of independent or continuous envelope-shaped membranes are formed on the outer peripheral surface of the perforated hollow tube to form a stock solution flow path material. An undiluted solution to which a coagulant is added is supplied from the outer peripheral side and the other end side of the spiral type membrane element wound at one end and sealed at one end, and at least one open end of the perforated hollow tube Is to take out the permeated liquid.

In the method for operating the spiral type membrane element according to the present invention, the addition of the flocculant causes the dissolved organic substances and the like in the undiluted solution to be flocculated. Not formed on. Thereby, clogging of the membrane due to formation of the gel layer is prevented, and reduction of the permeation flux is prevented.

Also, since the outer peripheral surface and one end surface of the spiral type membrane element are open without being covered with the exterior material, the stock solution containing the coagulant is supplied from the outer peripheral side and one end side of the membrane element. And the whole amount is filtered.

As described above, since the stock solution to which the coagulant is added is supplied from the outer peripheral side and one end side of the membrane element, contaminants including flocs generated by the coagulation are captured at the outer peripheral section and one end of the membrane element. Is done. Therefore, it is possible to uniformly remove contaminants by backwashing with, for example, permeated water. As a result, a stable permeation flux can be obtained for a long period of time.

In particular, in the above-mentioned membrane element, a space for supplying the undiluted solution is not required on the sealed end side.
The pressure vessel that houses the membrane element can be reduced in size. Further, by disposing the sealed end of the membrane element on the side of the undiluted solution inlet of the pressure vessel, it is possible to prevent dirt from being attached to the end face of the spiral membrane element due to the dynamic pressure of the undiluted solution during undiluted solution introduction. it can.

In the structure of the above-mentioned membrane element, dead space is not formed in the space between the membrane element and the pressure vessel due to the total filtration, so that germs such as microorganisms propagate and malodor is generated due to decomposition of organic substances. Also, there is no problem such as decomposition of the separation membrane, and high reliability can be obtained.

Further, since pressure is applied from all directions of the membrane element and no pressure causing displacement in the axial direction is applied, the envelope-like membrane wound around the perforated hollow tube is deformed into a bamboo shoot. There is no. This eliminates the need for a packing holder and an exterior material, thereby reducing parts costs and manufacturing costs. In addition, since the whole amount is filtered, a high recovery rate can be obtained without using a large pump for supplying the stock solution. Thereby, system costs and operating costs are reduced.

A method for operating a spiral-type membrane element according to a third aspect of the present invention is a method of operating the spiral membrane element, wherein a coagulant is added to the stock solution, and a plurality of independent or continuous envelope membranes are formed on the outer peripheral surface of the perforated hollow tube to form the stock solution flow path material. An undiluted solution to which a coagulant has been added is supplied from the outer peripheral side of a spiral-type membrane element wound at both ends and sealed at both ends, and a permeate is taken out from at least one open end of the perforated hollow tube. Things.

In the method for operating a spiral type membrane element according to the present invention, since a dissolved organic substance or the like in a stock solution is flocculated by the addition of a flocculant, a gel layer made of a gel-like substance having a large specific resistance to filtration is formed on the membrane surface. Not formed on. Thereby, clogging of the membrane due to formation of the gel layer is prevented, and reduction of the permeation flux is prevented.

Further, since the outer peripheral surface of the spiral type membrane element is open without being covered with the exterior material, the stock solution to which the coagulant is added is supplied from the outer peripheral side of the membrane element, and the whole amount is filtered.

As described above, since the stock solution to which the coagulant has been added is supplied from the outer peripheral side of the membrane element, contaminants including flocs generated by the coagulation are captured at the outer peripheral section of the membrane element. Therefore, it is possible to uniformly remove contaminants by backwashing with, for example, permeated water. As a result, a stable permeation flux can be obtained for a long period of time.

In particular, in the above-mentioned membrane element, a space for supplying the undiluted solution is not required at the both ends sealed, so that the pressure vessel for accommodating the membrane element can be downsized. Further, by disposing one of the sealed both ends of the membrane element on the side of the undiluted liquid inlet of the pressure vessel, it is possible to prevent dirt from adhering to the end face of the spiral membrane element due to the dynamic pressure of the undiluted liquid when introducing undiluted liquid. be able to.

Also, in the structure of the above membrane element, dead space is not formed in the space between the membrane element and the pressure vessel due to the total amount filtration, so that germs such as microorganisms propagate, and odors are generated due to decomposition of organic substances. Also, there is no problem such as decomposition of the separation membrane, and high reliability can be obtained.

Further, since pressure is applied from all directions of the membrane element and no pressure causing displacement in the axial direction is applied, the envelope-shaped membrane wound around the perforated hollow tube is deformed into a bamboo shoot. There is no. This eliminates the need for a packing holder and an exterior material, thereby reducing parts costs and manufacturing costs. In addition, since the whole amount is filtered, a high recovery rate can be obtained without using a large pump for supplying the stock solution. Thereby, system costs and operating costs are reduced.

In the processing system according to the fourth invention, the coagulant adding means for adding the coagulant to the stock solution, and a plurality of envelope-like membranes independent or continuous on the outer peripheral surface of the perforated hollow tube are provided in the stock solution flow path. A spiral-type membrane element wound around a material, and a stock solution to which a coagulant is added by a coagulant adding means is supplied from at least the outer peripheral side of the spiral-type membrane element, and at least a perforated hollow tube. The permeated liquid is led out from one opening end.

In the operation method of the spiral type membrane element according to the present invention, since the dissolved organic matter and the like in the stock solution are flocculated by the addition of the coagulant, the gel layer made of the gel-like substance having a large filtration specific resistance is formed on the membrane surface. Not formed on. Thereby, clogging of the membrane due to formation of the gel layer is prevented, and reduction of the permeation flux is prevented.

Further, since at least the outer peripheral surface of the spiral type membrane element is open without being covered with the exterior material, the stock solution containing the coagulant is supplied from at least the outer peripheral side of the membrane element, and the total filtration is performed. Done.

As described above, since the stock solution to which the coagulant has been added is supplied from at least the outer peripheral side of the membrane element, contaminants including flocs generated by coagulation are captured at least at the outer peripheral section of the membrane element. Therefore, it is possible to uniformly remove contaminants by backwashing with, for example, permeated water. As a result, a stable permeation flux can be obtained for a long period of time.

According to the structure of the spiral type membrane element described above, dead space S as shown in FIG.
Since no odor is formed, problems such as propagation of microorganisms such as microorganisms, generation of offensive odor due to decomposition of organic matter, and decomposition of the separation membrane do not occur, and high reliability can be obtained.

Further, since pressure is applied to the membrane element from all directions, there is no problem of deformation of the membrane element, and the packing holder and the exterior material become unnecessary. Further, since the whole amount is filtered, it is not necessary to use a large pump for supplying the undiluted solution. Therefore, cost can be reduced.

[0049]

FIG. 1 is a diagram showing a water treatment system according to one embodiment of the present invention.

The water treatment system shown in FIG. 1 comprises an agglutination reaction tank 100 provided with a stirrer 101 and a spiral type membrane element 1 described later. Raw water such as river water is supplied to the pipe 104
To the coagulation reaction tank 100. Coagulation reaction tank 1
The flocculant is added to the raw water in 00 by a flocculant supply means 102 and is stirred by the stirrer 101. As a result, the dissolved organic matter and the like in the raw water undergo a flocculation reaction to form flocs.

The raw water subjected to the coagulation treatment in the coagulation reaction tank 100 is supplied to a pump 103 through a pipe 105, and supplied to the spiral membrane element 1 by the pump 103. The spiral membrane element 1 derives permeated water by total filtration. The permeated water obtained by the spiral membrane element 1 is supplied to the outside of the system through a pipe 106.

The flocculant supplied by the flocculant supplying means 102 is not particularly limited, and for example, aluminum salts such as polyaluminum chloride and aluminum sulfate,
Iron salts such as ferric chloride and polysulfuric acid, magnesium salts, and the like can be used. In addition to these flocculants, various polymer polymers can be used in combination as flocculants.

The amount of the coagulant to be added is appropriately selected within a range where the filtration resistance is minimized.
pm. In addition, it is preferable to determine the addition amount according to the quality of raw water.

FIG. 2 is a partially cutaway perspective view of the spiral membrane element used in the water treatment system of FIG.
FIG. 3 is a cross-sectional view showing an example of the envelope-shaped membrane of the spiral membrane element shown in FIG. 2, and FIG. 4 is a cross-sectional view showing another example of the envelope-shaped membrane of the spiral membrane element shown in FIG. is there.

The spiral type membrane element 1 shown in FIG.
Includes a spiral-shaped membrane element 1a formed by winding a plurality of independent envelope-shaped membranes 3 or a plurality of continuous envelope-shaped membranes 3 on the outer peripheral surface of a water collecting pipe 2 composed of a perforated hollow pipe. . A raw water spacer (raw liquid flow path material) 4 is inserted between the envelope films 3 in order to prevent the envelope films 3 from adhering to each other and to reduce the film area, and to form a flow path for raw water. Have been. Spiral membrane element 1
The outer peripheral surface of a is covered with an outer peripheral channel material 5 made of a net formed of plastic, metal, rubber, fiber, or the like such as polypropylene, polyethylene, or polystyrene.

As shown in FIG. 3 and FIG.
Is formed by superposing two separation membranes 7 on both sides of a permeated water spacer (permeated liquid flow path material) 6 and bonding three sides thereof, and the opening of the envelope-shaped membrane 3 is formed on the outer periphery of the water collecting pipe 2. Attached to the surface. 10 kgf / c for the separation membrane 7
Low pressure reverse osmosis membranes, ultrafiltration membranes, microfiltration membranes, etc., operated at m ² or less are used.

In the example of FIG. 3, a plurality of envelope-shaped membranes 3 are formed by independent separation membranes 7, respectively. In the example of FIG.
A plurality of envelope membranes 3 are formed by folding a continuous separation membrane 7.

If the thickness of the raw water spacer 4 is larger than 0.5 mm, it becomes difficult to capture contaminants in the raw water at least at the outer peripheral portion of the membrane element 1. On the other hand, raw water spacer 4
If the thickness is smaller than 0.1 mm, the envelope-shaped films 3 are easily brought into contact with each other, and the film area is reduced. Therefore, the thickness of the raw water spacer 4 is 0.1 mm or more and 0.5 mm or more.
The following is preferred.

When the thickness of the outer peripheral channel member 5 is larger than 30 mm, the volume efficiency of the membrane element 1 with respect to the pressure vessel storing the membrane element 1 is reduced. On the other hand, if the thickness of the outer peripheral portion flow path member 5 is smaller than 0.6 mm, it becomes difficult to discharge contaminants attached to at least the outer peripheral portion of the membrane element 1 during backflow washing of the permeated water to the outside of the system. Therefore, it is preferable that the thickness of the outer peripheral channel member 5 is 0.6 mm or more and 30 mm or less.

FIG. 5 is a sectional view showing an example of a method of operating the spiral type membrane element of FIG. As shown in FIG. 5, the pressure vessel (pressure-resistant vessel) 10 includes a cylindrical case 11 and a pair of end plates 12a and 12b. A raw water inlet 13 is formed on one end plate 12a, and the other end plate 1
A raw water outlet 15 is formed in 2b. A permeated water outlet 14 is provided at the center of the other end plate 12b.

The spiral membrane element 1 is housed in a cylindrical case 11, and both open ends of the cylindrical case 11 are sealed by end plates 12a and 12b, respectively. One end of the water collecting pipe 2 is fitted to the permeated water outlet 14 of the end plate 12b, and an end cap 16 is attached to the other end. End plate 1
A pipe 17 and a valve 18 are connected to the raw water outlet 15 of 2b.

During the operation of the spiral membrane element 1, the raw water 51 is introduced into the pressure vessel 10 from the raw water inlet 13 of the pressure vessel 10. The raw water 51 is supplied from at least the outer peripheral side of the spiral membrane element 1 to the raw water spacer 4.
Along the space between the envelope-shaped membranes 3. In the example of FIG. 5, raw water 51 enters between the envelope-shaped membranes 3 from the outer peripheral side and both end sides of the spiral membrane element 1. The permeated water that has passed through the separation membrane 7 flows into the water collecting pipe 2 along the permeated water spacer 6. Thereby, the permeated water outlet 14 of the pressure vessel 10
The permeated water 52 is taken out from the tank. In this way, total filtration is performed.

In this case, the thickness of the raw water spacer 4 is so small that contaminants such as turbid substances are captured at least at the outer peripheral portion (the outer peripheral portion and both ends in the example of FIG. 5) of the membrane element 1. A cake layer of a contaminant is formed on at least the outer peripheral portion of the device. At least the outer periphery of the membrane element 1 is subjected to cake filtration by the cake layer, and the inside of the membrane element 1 is subjected to membrane filtration by the separation membrane 7.

The raw water may be partially extracted from the raw water outlet 15 by opening the valve 18. In this case, a flow of raw water can be formed at the outer peripheral portion of the membrane element 1. Thereby, a part of the contaminants can be discharged to the outside of the pressure vessel 10 while the sedimentation of the contaminants in the raw water is suppressed.

After filtration for a certain period of time, backwashing with permeated water is performed from the permeation side. During backwashing, the permeated water back-filtered from the water collection pipe 2 flows along the raw water spacer 4 at least toward the outer peripheral portion. Thereby, the contaminants captured at least at the outer peripheral portion of the membrane element 1 are easily peeled off. At this time, when the valve 18 is opened while supplying the raw water from the raw water inlet 13, the separated contaminants are discharged out of the system. As a result, the permeation flux is remarkably recovered as compared with before the backwashing.

In the water treatment system of the present embodiment, the dissolved organic matter and the like in the raw water is flocculated by the addition of the flocculant, so that a gel layer made of a gel-like substance having a large filtration specific resistance is not formed on the membrane surface. . Thereby, clogging of the membrane due to formation of the gel layer is prevented, and reduction of the permeation flux is prevented.

Since the raw water to which the coagulant has been added is supplied from at least the outer peripheral side of the spiral membrane element 1, the contaminants including flocs generated by the coagulation are captured at least at the outer peripheral section of the membrane element 1. Therefore, the contaminants can be uniformly removed by backwashing. As a result, a stable amount of permeated water can be maintained over a long period of time.

In particular, in the spiral type membrane element 1 used in the water treatment system of the present embodiment, the dead space shown in FIG. Since a dead space such as the space S is not formed, problems such as propagation of germs such as microorganisms, generation of offensive odor due to decomposition of organic matter, and decomposition of the separation membrane do not occur, and high reliability can be obtained.

Further, since pressure is applied to the membrane element 1 from all directions, there is no problem of deformation of the membrane element 1 and the packing holder and the exterior material are not required. Thereby,
Component and manufacturing costs are reduced.

Further, since the whole amount is filtered, it is not necessary to use a large pump 103 for supplying raw water.
Thereby, the system cost is reduced.

FIG. 6 is a front view showing another example of the spiral membrane element used in the water treatment system of FIG. In FIG. 6, the illustration of the outer peripheral channel material is omitted.

The spiral type membrane element 1 shown in FIG.
In, both end portions of the spiral membrane element 1a are sealed with a resin layer 19. In the spiral membrane element 1 shown in FIG. 6B, one end of the spiral membrane element 1 a is sealed with a resin layer 19.

The spiral membrane element 1 shown in FIG.
When used in the water treatment system of FIG. 1, raw water to which a coagulant has been added is supplied from the outer peripheral side of the membrane element 1. When the spiral membrane element 1 of FIG. 6B is used in the water treatment system of FIG. 1, raw water to which a coagulant has been added is supplied from the outer peripheral side and one end side of the membrane element 1.

In the spiral type membrane element 1 shown in FIGS. 6A and 6B, the number of working steps in manufacturing increases, but a space for supplying raw water to both ends or one end of the membrane element 1 becomes unnecessary. Therefore, the pressure vessel can be reduced in size, and the spiral membrane module in which the membrane element 1 is housed in the pressure vessel can be reduced in size.

Further, by arranging the end portion of the membrane element 1 sealed with the resin layer 19 on the raw water inlet side of the pressure vessel, dirt adheres to the end face of the membrane element 1 due to the dynamic pressure of the raw water when the raw water is introduced. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a water treatment system in one embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view of a spiral-wound membrane element used in the water treatment system of FIG.

FIG. 3 is a cross-sectional view showing an example of an envelope-shaped membrane of the spiral membrane element of FIG.

FIG. 4 is a cross-sectional view showing another example of the envelope-shaped membrane of the spiral membrane element of FIG.

FIG. 5 is a cross-sectional view showing an example of a method of operating the spiral membrane element of FIG.

FIG. 6 is a front view showing another example of the spiral membrane element used in the water treatment system of FIG. 1.

FIG. 7 is a partially cutaway perspective view of a conventional spiral-type membrane element.

FIG. 8 is an external perspective view of a conventional spiral-type membrane element.

FIG. 9 is a cross-sectional view showing an example of a conventional method of operating a spiral-type membrane element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spiral type membrane element 1a Spiral type membrane element 2 Water collecting pipe 3 Envelope type membrane 4 Raw water spacer 5 Outer flow path material 6 Permeated water spacer 7 Separation membrane 10 Pressure vessel 13 Raw water inlet 14 Permeated water outlet 51 Raw water 52 Permeated water 100 Coagulation Reaction tank 101 Stirrer 102 Coagulant supply means 103 Pump

Claims (4)

[Claims] An outer periphery of a spiral-type membrane element in which a coagulant is added to a stock solution and a plurality of independent or continuous envelope membranes are wound around the outer peripheral surface of a perforated hollow tube via a stock solution flow path material. A method for operating a spiral-wound membrane element, comprising supplying a stock solution to which the coagulant has been added from the side and both ends, and taking out a permeate from at least one open end of the perforated hollow tube. 2. A coagulant is added to a stock solution, and a plurality of independent or continuous envelope membranes are wound around the outer peripheral surface of a perforated hollow tube via a stock solution flow path material, and one end is sealed. A spiral solution comprising supplying a stock solution to which the flocculant is added from the outer peripheral side and the other end side of the spiral membrane element, and taking out a permeate from at least one open end of the perforated hollow tube. How to operate the mold membrane element. 3. A coagulant is added to the stock solution, and a plurality of independent or continuous envelope membranes are wound around the outer peripheral surface of the perforated hollow tube via the stock solution channel material, and both ends are sealed. Operating the spiral membrane element, wherein a stock solution to which the coagulant is added is supplied from the outer peripheral side of the spiral membrane element, and a permeate is taken out from at least one open end of the perforated hollow tube. Method. 4. A spiral comprising a coagulant adding means for adding a coagulant to a stock solution, and a plurality of independent or continuous envelope membranes wound around a perforated hollow outer peripheral surface via a stock solution flow path material. A stock solution to which a coagulant is added by the coagulant adding means is supplied from at least an outer peripheral side of the spiral membrane element, and a permeate is supplied from at least one open end of the perforated hollow tube. Is derived.