WO2015064495A1

WO2015064495A1 - Flat membrane cartridge for waste water processing

Info

Publication number: WO2015064495A1
Application number: PCT/JP2014/078332
Authority: WO
Inventors: 憲史島田; 純輔森田; 北河　享; 昌男東
Original assignee: 東洋紡株式会社
Priority date: 2013-10-30
Filing date: 2014-10-24
Publication date: 2015-05-07
Also published as: MY191215A; JP2015085253A; CN105682779A; JP5742041B2; CN105682779B

Abstract

[Problem] To provide a flat membrane cartridge with which it is possible to select a channel material and a buffer material that can reduce pressure loss and reduce suction pressure distribution on the surface of a separation membrane, and which can increase a waste water processing flow rate per unit membrane surface area using low power. [Solution] Provided is a flat membrane cartridge for waste water processing, in which, with respect to the front and back surfaces of a membrane support plate which is made of resin and which has a level difference on the front and back surfaces so that the edges are higher than the center, separation membranes are adhered to such front and back surfaces along the edges thereof so as to cover the center of the membrane support plate. The flat membrane cartridge is characterized by the following: between the center of the membrane support plate and the separation membrane, disposed are a channel material and a buffer material, in that order from the membrane support plate side; the channel material has openings of 0.5-3.2mm in the horizontal and vertical directions, a wire diameter of 0.4-1.0mm in the horizontal and vertical directions, a thickness of 0.6-2.0mm, and a porosity of 20-60%; and the buffer material has a basis weight of 10-110g/m², and a thickness of 0.1-0.5mm.

Description

Flat membrane cartridge for wastewater treatment

The present invention relates to a flat membrane cartridge used for membrane filtration separation of a membrane filtration wastewater treatment apparatus.

In recent years, the quality and quantity required for domestic and industrial water has increased against the background of global population growth, industrialization, urbanization, and improvement of living standards.

In addition to using natural water obtained from nature, water resources can be secured by obtaining fresh water from seawater using evaporation or reverse osmosis, or using reverse osmosis from salt-containing brine. There is a way to get fresh water. However, natural resources of fresh water are limited, and it is said that the availability tends to become narrower due to the influence of abnormal weather in recent years. Moreover, in order to produce fresh water using the evaporation method or the reverse osmosis method, energy for heating and pressurization is required, so the area used is limited.

Another method is to reuse sewage. In the conventional sewage treatment, the organic components in the sewage are decomposed with activated sludge, and the treated water is discharged through sedimentation filtration or the like, but it is difficult to completely remove bacteria such as Escherichia coli. However, MBR (Membrane Separation Activated Sludge Method) filters the water treated with activated sludge using a separation membrane, so that it is possible to completely remove the above harmful bacteria group, There are many advantages such as ease of operation management, and in recent years it has become a technology that has attracted much attention. The water separated by MBR can be used not only as life scenery maintenance water and middle water, but also can be obtained in combination with reverse osmosis. The reverse osmosis method using seawater requires a high pressure against the salinity, but is characterized in that it can be produced safely and with low energy by using treated water obtained by MBR as raw water.

Thus, MBR is attracting attention as a method for resolving water shortages expected in the future. In order to further improve this method and complete a low-cost and high-efficiency system, there is a need to ensure water permeability while maintaining membrane separation performance.

In addition, if the membrane is used for a long time in a state where it is immersed in activated sludge, the pores will be blocked by secretions from the activated sludge, the dead bodies themselves, and contaminants contained in the sludge. It may be necessary to increase the pump power to cope with this. This is the biggest problem when using a membrane called fouling. In order to solve this problem, an operation of eliminating the fouling by washing the membrane with a chemical such as sodium hypochlorite or hydrochloric acid to return the membrane to a fresh state is performed. Therefore, it is necessary for the membrane and the cartridge to have strength to withstand backwashing as well as resistance to these drugs.

However, the cleaning operation with these chemicals has many problems in terms of economy and environment, such as the inability to perform filtration operation during that time, chemical costs, labor, and drainage treatment of the chemicals. Therefore, the biggest issue is how to prevent fouling and allow it to be used for a longer period of time so that the cleaning operation with the medicine is reduced.

In order to obtain a larger amount of membrane permeated water with less power, it is necessary to reduce the pressure loss in the membrane and the membrane permeated water flow path. In addition, in order to effectively apply the suction pressure to the entire membrane surface, it is also required to reduce the flow unevenness in the membrane permeate channel.

Currently, as an immersion-type filtration membrane module, a plurality of hollow fiber membrane cartridges as in Patent Document 1 and flat membrane cartridges as in Patent Literature 2 are proposed. Hollow fiber membrane cartridges can increase the membrane area per unit volume and increase the amount of wastewater treatment, but sludge and contaminants can adhere to the cartridge and easily accumulate in the gaps between the bundles of hollow fibers. There is a problem. On the other hand, the flat membrane cartridge is inferior in the membrane area that can be secured, but has an advantage in that there is little adhesion and accumulation of sludge and impurities on the membrane surface.

As a flat membrane type membrane cartridge, on the surface of a membrane support plate as proposed in Patent Document 3, a plurality of open slits communicate with the water collecting portion at one end from the upper side to the lower side of the membrane support plate. And a type in which a membrane permeate flow path is formed inside a membrane support plate having a mesh structure as proposed in Patent Document 4.

Further, in Patent Document 5, a flat membrane cartridge in which the specification of the channel material is selected based on the pressure loss when the membrane permeate flows in the outlet direction through the gap between the membrane support plate on which the channel material is disposed and the separation membrane. Has been proposed. However, in the flat membrane cartridge selected in this way, pressure loss during suction is not taken into consideration, so that the operation load of the suction pump and the membrane cleaning blower increases, and the wastewater treatment cost increases.

Japanese Patent Laid-Open No. 07-136470 Japanese Patent Laid-Open No. 11-033369 Japanese Patent Laid-Open No. 08-281264 JP 2012-045515 A JP 2001-321766 A

The present invention has been made in view of the above-described state of the prior art, and its purpose is to select a flow path material and a buffer material that can achieve both a reduction in pressure loss and a reduction in the suction pressure distribution on the surface of the separation membrane. Another object of the present invention is to provide a flat membrane cartridge that can increase the wastewater treatment flow rate per unit membrane area with low power.

As a result of intensive studies on a suitable channel material and cushioning material to achieve the above object, the present inventor has found that a channel material having a specific opening, wire diameter, thickness, and space ratio, and a specific basis weight and thickness. By using each of the buffer materials having the above, it was found that the flow rate of the permeated water per pressure loss was increased, and the present invention was completed.

That is, the present invention has the following configurations (1) to (4).
(1) Along the peripheral portion so as to cover the central portion of the membrane support plate with respect to both the front and back surfaces of the resin-made membrane support plate provided with steps on the front and back surfaces so that the peripheral portion is higher than the central portion. A flat membrane cartridge for wastewater treatment formed by adhering a separation membrane, wherein a flow path material and a buffer material are arranged in order from the membrane support plate side between the central portion of the membrane support plate and the separation membrane, The material has an opening of 0.5 to 3.2 mm in both length and width, a wire diameter of 0.4 to 1.0 mm in both length and width, a thickness of 0.6 to 2.0 mm, and a space ratio of 20 to 60%. A flat membrane cartridge for wastewater treatment, wherein the buffer material has a basis weight of 10 to 110 g / m ² and a thickness of 0.1 to 0.5 mm.
(2) The wastewater treatment apparatus according to (1), wherein the permeated water flows from the outside of the separation membrane in the order of the buffer material, the flow path material, and the permeated water outlet provided at the end of the membrane support plate. Flat membrane cartridge.
(3) The flat membrane cartridge for wastewater treatment according to (1) or (2), wherein the flow path material is a plain weave type resin mesh and the cushioning material is a nonwoven fabric. (4) The peripheral edge of the membrane support plate is 0.6 to 2 mm higher than the central part, and the difference in height between the central part and the peripheral part where the resin mesh and the nonwoven fabric are arranged is 0.5 mm or less ( 1) A flat membrane cartridge for wastewater treatment according to any one of (3).

The flat membrane cartridge of the present invention uses a resin mesh having a specific opening, wire diameter, thickness, and space ratio as a flow path material, and further uses a nonwoven fabric having a specific weight and thickness as a buffer material. It is possible to achieve both reduction of pressure loss and reduction of suction pressure distribution on the separation membrane surface. Thereby, a large amount of waste water can be treated by increasing the amount of water per membrane area, and low-cost operation with low power can be achieved.

1 schematically shows the configuration of one side of a flat membrane cartridge for wastewater treatment according to the present invention. It is a schematic diagram which shows an example of the conventional film | membrane support plate which has a groove-shaped channel.

The flat membrane cartridge for wastewater treatment of the present invention will be described with reference to the drawings.

In the flat membrane cartridge of the present invention, as shown in FIG. 1, a resin mesh is arranged as a flow path material 2 in a central portion 5 of a membrane support plate 3, a buffer material 6 is arranged thereon, and a membrane is further formed thereon. The separation membrane 1 is bonded along the peripheral edge 4 of the support plate 3. In the present invention, since the separation membrane 1 is pressed against the flow path material 2 side at the time of suction, a configuration in which the buffer material 6 having a role of protecting the membrane is disposed between them is essential. In FIG. 1, only the configuration of one side of the membrane support plate 3 of the flat membrane cartridge is shown at the time of suction, but the present invention has the same configuration on both the front and back sides of the membrane support plate 3.

The flow of the membrane permeated water in the flat membrane cartridge of the present invention will be described with reference to FIG. 1. The liquid to be treated is brought into contact with the outer surface of the separation membrane 1 and filtered from the outside to the inside of the separation membrane 1. The permeated water attached to the end of the membrane support plate 3 passes through the buffer material 6 disposed between the separation membrane 1 and the membrane support plate 3 and the gap in the flow path material 2 in this order. It flows in the direction of the water intake port 7 and is discharged from the permeated water intake port 7 to the outside of the flat membrane cartridge.

In the flat membrane cartridge of the present invention, it is preferable that the peripheral edge portion 4 of the membrane support plate 3 is 0.6 to 2 mm higher than the central portion 5. The buffer material 6 is arranged, and in this case, the step between the central portion 5 and the peripheral edge portion 4 is preferably 0.5 mm or less. The buffer material 6 is disposed so as to cover the flow path material 2 bonded to the membrane support plate 3 and is bonded to the flow path material 2. The separation membrane 1 is bonded at the peripheral edge portion 4 so as to cover the membrane support plate 3 on which the flow path material 2 and the buffer material 6 are arranged.

If the thickness of the concave space in the central portion 5 of the membrane support plate 3 (step difference from the peripheral edge portion 4) is too large, it is necessary to increase the thickness per flat membrane cartridge, and the number of installable units per membrane unit is reduced. It will decrease. Further, if the concave space of the central portion 5 is enlarged without changing the thickness, it is necessary to make the central portion 5 of the membrane support plate 3 thin, and the strength of the flat membrane cartridge is reduced. If the thickness of the concave space in the central portion 5 of the membrane support plate 3 is too small, the membrane permeate flow channel is narrowed and the pressure loss is increased. Moreover, when the level | step difference with the peripheral part 4 is too large, the damage by the separation membrane 1 bending at the level | step-difference part, or peeling of the separation membrane 1 will arise. Therefore, it is preferable that the central portion 5 and the peripheral portion 4 of the membrane support plate 3 have a height difference as described above.

The material of the separation membrane 1 is not particularly limited, and for example, a material made of polyvinyl chloride, chlorinated polyvinyl chloride, polyether sulfone, polytetrafluoroethylene, or a mixture thereof can be appropriately selected. The thickness of the separation membrane 1 is preferably 80 to 150 μm. If the thickness is too large, the water permeability resistance is increased, so that the water permeability may be decreased. Conversely, if the thickness is too thin, the film strength may be insufficient.

The material of the membrane support plate 3 is not particularly limited as long as it has a rigidity that can hold the shape of the entire flat membrane cartridge, and for example, ABS resin, vinyl chloride, and polycarbonate can be appropriately selected. The size of the membrane support plate is preferably 300 mm × 200 mm to 1,200 mm × 550 mm in length and width, the width of the periphery is 10 mm to 20 mm, and the thickness is preferably 2 to 4 mm in the center. The step between the central portion 5 and the peripheral portion 4 of the membrane support plate 3 can be formed by attaching a plate-like member of the same material to the peripheral portion of the membrane support plate.

The channel material 2 needs to have a specific range of openings, wire diameter, thickness, and space ratio in order to satisfy the function as a permeate channel. As a commercial product, for example, a DOP-18K plain weave type resin mesh manufactured by Nippon Filcon Co., Ltd. can be preferably used. It is preferable that the flow path member 2 is accommodated in a concave space in a central portion formed by being surrounded by a peripheral edge portion of the membrane support plate. The material of the resin mesh used for the flow path member 2 is not particularly limited, but can be appropriately selected from resins such as polyester and nylon.

The space ratio of the channel material 2 needs to be 20 to 60%. The space ratio is a ratio of the area of the opening portion to the total area in the flow path space formed from the resin mesh used for the flow path material 2, and is calculated by the following equation.
Space ratio (%) = (opening) ² / [(opening) + (wire diameter)] ² × 100
The space ratio calculated from the vertical opening and the wire diameter of the flow path material 2 and the average value of the space ratio calculated from the horizontal opening and the wire diameter of the flow path material 2 are the space of the flow path material 2. Rate. If the flow path material 2 outside the range of 20 to 60% is used, the distribution of the suction pressure in the flow path will increase, and the suction pressure on the film surface will be different, making the entire membrane surface effective. Can no longer function. If the flow rate of the flow path member 2 is too large, the separation membrane 1 sticks to the opening of the flow path member 2 during suction, and narrows the flow path. Moreover, when the space ratio is small, the pressure loss of the membrane permeated water in the flow path member 2 increases.

As for the opening and the wire diameter of the flow path material 2, the opening is 0.5 to 3.2 mm both vertically and horizontally and the wire diameter is 0.4 to 1.0 mm both vertically and horizontally so that the space ratio falls within 20 to 60%. The range is selected. In addition, the thickness of the flow path member 2 needs to be 0.6 to 2.0 mm. If it is smaller than 0.6 mm, the passage space of the membrane permeated water becomes narrow and the pressure loss increases. If the thickness of the mesh is larger than 2.0 mm, the thickness of the flat membrane cartridge itself increases, and the number of installable sheets per membrane unit decreases.

The buffer material 6 has a role of absorbing the stress applied to the separation membrane 1, preventing it from sticking to the flow path material 2 with suction pressure, and protecting the separation membrane 1. Examples of the buffer material 6 include a nonwoven fabric, a net-like structure, sponge, rubber, and a film sheet. In the present invention, the separation membrane is prevented from sticking to the flow path material by suction, the water permeability resistance is small, and the thickness A non-woven fabric that has strength even when it is thin and can retain its shape is preferable. The buffer material 6 preferably has a basis weight of 10 to 110 g / m ² and a thickness of 0.1 to 0.5 mm. Regarding the basis weight, if it is too small, it does not function as a buffer material for protecting the separation membrane 1, and the separation membrane 1 and the flow path material 2 stick to each other at the time of suction. . Regarding the thickness, if it is too thin, it does not function as a cushioning material, and if it is too thick, the step between the peripheral edge portion 4 and the central portion 5 of the membrane support plate 3 becomes large and the adhesive force between the separation membrane 1 and the membrane support plate 3 is weakened. Absent. The size of the buffer material 6 preferably has the same plane area as that of the channel material 2 from the viewpoint of preventing the separation membrane 1 from sticking to the channel material 2. The material of the nonwoven fabric is not particularly limited, and for example, polyester, polypropylene, and the like can be selected as appropriate.

Adhesion between the separation membrane 1 and the membrane support plate 3 is sufficient as long as the adhesion state between the separation membrane 1 and the peripheral edge portion 4 of the membrane support plate 3 can be maintained. For example, conventionally known methods such as ultrasonic welding and thermal welding are known. It can be done by the method. In the case of ultrasonic welding, the separation membrane 1 is disposed so as to cover the membrane support plate 3 to which the flow path material 2 is bonded and the buffer material 6 placed on the flow path material 2, and the peripheral portion of the membrane support plate 3 4, the separation membrane 1 and the membrane support plate 3 can be welded by ultrasonic vibration output from the horn.

The permeated water intake 7 is provided at the end of the membrane support plate 3, and preferably has an inner diameter of 3 to 6 mm and a cross-sectional area of the inner opening of 7 to 28 mm ² . If both the inner diameter and the cross-sectional area of the permeate intake port 7 are larger than the above ranges, the thickness of the membrane cartridge increases, and the number of sheets that can be installed per membrane unit may decrease. If it is smaller than the above range, the pressure loss during suction increases, and it is difficult to obtain a sufficient treatment flow rate.

The pure water FR of the separation membrane 1 of the present invention is preferably in the range of 15 to 50 mL / cm ² / min / bar. The pure water flux (pure water FR) is a volume of pure water that can be passed per unit time, unit area, and unit pressure, and represents the water permeability of the separation membrane 1. If the pure water FR is too small, it will be necessary to increase the number of flat membrane cartridges and increase the pressure by the pump in order to secure the amount of wastewater treatment required for practical use. The problem is big. On the other hand, in order to increase the pure water FR, it is necessary to increase the pore diameter of the separation membrane 1. However, by increasing the pore diameter, the fractionation performance deteriorates and the function as a membrane may not be performed sufficiently. There is.

If the configuration of the flat membrane cartridge of the present invention is adopted, the suction pressure distribution becomes small, and the entire membrane surface can be used more evenly. Moreover, the uneven flow in the flow path is also reduced, the pressure loss can be reduced, and the membrane permeate flow rate can be increased. When the membrane permeate flows in the direction of the permeate water intake 7 through the membrane permeate channel formed by the channel material 2 provided between the separation membrane 1 and the membrane support plate 3, the membrane permeate flow rate (L / h) ) / Pressure loss (kPa), the value obtained is preferably 1.25 or more. If this value is 1.25 or more, the suction power of the flat membrane can be kept low, and a good wastewater treatment flow rate per unit membrane area can be achieved with low power.

The effect of the flat membrane cartridge of the present invention is shown by examples, but the present invention is not limited to these. Evaluation of the characteristic value in the present invention was performed according to the following method.

(1) Pure water flux (FR)
Pure water FR was measured by the method described below. After the separation membrane was cut into a circle of φ90 mm and set in a filtration holder, pure water FR was determined from the following formula from the amount of water permeated from the holder outlet by applying a water pressure of 0.5 bar. The water used for the filtration was RO water at 25 ° C. (water filtered using a reverse osmosis membrane), and 30 seconds after the water pressure was applied as the sampling start time. Moreover, the water surface height from the film surface was adjusted to be 3 cm ± 1 cm.
(Pure water FR [mL / cm ² / min / bar]) = (Q [mL / min]) / (A [cm ² ]) / (P [bar])
(Q: water permeability for 1 minute, A: effective membrane area = 48 cm ² , P: water pressure = 0.5 bar)

(2) Resin mesh wire diameter, mesh opening, space ratio Wire diameter (mm), mesh opening (mm), and space ratio (%) were measured by the methods described below. For the wire diameter, the diameter of the wire constituting the resin mesh used for the flow path member 2 was measured with a caliper. Further, the opening was calculated by measuring the length per 10 wire rods with calipers, subtracting the wire diameter by the number of wires in the section, and assigning by the number of openings. The space ratio was calculated from the following formula.
Space ratio = (opening) ² / [(opening) + (wire diameter)] ² × 100
The space ratio calculated from the vertical opening and the wire diameter of the flow path material 2 and the average value of the space ratio calculated from the horizontal opening and the wire diameter of the flow path material 2 are the space of the flow path material 2. Rate.

(3) Membrane permeated water amount, suction pressure, and pressure loss Membrane permeated water amount and suction pressure were measured by the methods described below. A flat membrane cartridge was fixed vertically at a position 0.2 m high from the bottom of a plastic container having a height of 0.9 m, a width of 0.4 m, and a depth of 0.2 m. Pure water was supplied to a height of 0.8 m from the bottom, and the flat membrane cartridge was immersed. The permeate water intake port of the flat membrane cartridge was connected to a fixed liquid feed pump (roller pump), and suction filtration was performed with the rotation speed set to 50 rpm. The pressure gauge was connected between the flat membrane cartridge and the liquid feed pump. During suction filtration, the water level was kept constant, and the water temperature in the container was maintained at 25 ° C. Membrane permeated water was collected from the discharge port of the liquid feed pump. Membrane permeated water weight (kg / min) was measured with an electronic balance. The weight of membrane permeated water was converted to the amount of membrane permeated water at 25 ° C. according to the following formula.
Permeated water amount (L / min) = Permeated water weight (kg / min) /0.99704 (kg / L)
Further, the suction pressure was confirmed from the indicated value of the pressure gauge at the time of collecting the membrane permeated water, and the pressure loss (Pa) of the flat membrane cartridge was obtained.

(4) Fabric weight of nonwoven fabric The fabric weight of a nonwoven fabric was measured by weighing an nonwoven fabric cut to 10 cm square with an electronic balance, and the weight per 1 m ² was calculated from the result to determine the fabric weight of the nonwoven fabric [g / m ² ].

(5) Thickness of non-woven fabric The thickness of the non-woven fabric was determined by measuring the thickness of any five points using a thickness meter, and taking the average value.

Example 1
A membrane cartridge was manufactured with the following configuration to obtain a flat membrane cartridge for wastewater treatment.
By attaching the vinyl chloride resin peripheral portions (width 12.5 mm) of different thicknesses to the front and back surfaces of the vinyl chloride resin membrane support plate (height 315 mm, width 225 mm) without any gaps, the thickness of the peripheral portion A membrane support plate having a height of 6 mm and a peripheral edge 1 mm higher than the center was prepared. Moreover, a rectangular penetration part was provided in a part of the membrane support plate, and treated water could be taken out in communication with the penetration part, and a nozzle for a permeated water intake having a cross-sectional area of 8 mm ² was attached.
At the center of this membrane support plate, resin mesh shown in Table 1 as a flow path material: DOP-18K (height 290 mm, width 200 mm) as shown in Table 1 was set and adhered to the membrane support plate with a water-resistant adhesive. Then, a membrane permeate channel was formed. Details of the resin mesh are as shown in Table 1.
The membrane support plate and the resin mesh were bonded, and a nonwoven fabric made of polyethylene terephthalate: Hirose Paper Co., Ltd. 05TH-60 (height 285 mm, width 195 mm) was set as a cushioning material on the upper surface of the resin mesh. The details of the thickness and basis weight of the nonwoven fabric are as shown in Table 1. Further, a separation membrane (height 305 mm, width 215 mm, thickness 0.13 mm) was bonded to the peripheral portion of the membrane support plate without a gap from the upper part of the nonwoven fabric. In the same way, the separation membrane was adhered to the back surface to obtain a flat membrane cartridge.
The separation membrane used was a membrane component having a thickness of 130 μm, an average pore diameter of 0.3 μm, and pure water FR of 30 mL / cm ² / min / bar.
The details of the flat membrane cartridge of Example 1 are as shown in Table 1.

(Example 2)
A flat membrane cartridge having a configuration similar to that of Example 1 except that the peripheral edge of the flat membrane cartridge is 1.2 mm higher than the central portion, and a resin mesh having a space ratio of 26.3%: Nippon Filcon Co., Ltd. DOP-15K is used. A membrane cartridge was made. Details of the flat membrane cartridge of Example 2 are as shown in Table 1.

Example 3
A flat membrane cartridge having the same configuration as in Example 1 except that the peripheral portion of the flat membrane cartridge is 2.0 mm higher than the central portion, and a resin mesh with a space ratio of 52.7% is used. It was created. The details of the flat membrane cartridge of Example 3 are as shown in Table 1.

Example 4
The peripheral edge of the flat membrane cartridge is 1.0 mm higher than the center, and the resin ratio is: 22.7%, mesh opening: 0.55 mm (vertical), 0.55 mm (horizontal): Nippon Filcon Co., Ltd. DOP A flat membrane cartridge having the same configuration as in Example 1 was prepared except that −15K was used. The details of the flat membrane cartridge of Example 4 are as shown in Table 1.

(Examples 5 and 6)
Nonwoven fabric with a basis weight of 15 g / m ² and a thickness of 0.12 mm: Toyobo Co., Ltd. Ecule 3151A (Example 5), and a nonwoven fabric with a basis weight of 100 g / m ² and a thickness of 0.39 mm: Toyobo Co., Ltd. A flat membrane cartridge having the same configuration as in Example 1 was prepared except that was used as a buffer material. Details of the flat membrane cartridges of Examples 5 and 6 are as shown in Table 1.

(Example 7)
A flat membrane cartridge having a configuration similar to that of Example 1 except that the peripheral edge of the flat membrane cartridge is 2.0 mm higher than the central portion, and a resin mesh having a space ratio of 26.1%: Nippon Filcon Co., Ltd. OP-16K is used. A membrane cartridge was made. The details of the flat membrane cartridge of Example 7 are as shown in Table 1.

(Comparative Example 1)
A flat membrane cartridge having a configuration similar to that of Example 1 except that the peripheral edge of the flat membrane cartridge is 0.5 mm higher than the central portion and a resin mesh having a space ratio of 18.2%: Nippon Filcon Co., Ltd. DOP-50 is used. A membrane cartridge was made. Details of the flat membrane cartridge of Comparative Example 1 are as shown in Table 1.

(Comparative Example 2)
A flat membrane cartridge having the same configuration as in Example 1 except that the peripheral portion of the flat membrane cartridge is 2.0 mm higher than the central portion, and a resin mesh with a space ratio of 71.8% is used. It was created. Details of the flat membrane cartridge of Comparative Example 2 are as shown in Table 1.

(Comparative Example 3)
The peripheral edge of the flat membrane cartridge is 1.0 mm higher than the center, and the resin ratio is: 27.3%, mesh opening: 0.42 mm (vertical), 0.45 mm (horizontal): Nippon Filcon Co., Ltd. DOP A flat membrane cartridge having the same configuration as in Example 1 was prepared except that −25F was used. Details of the flat membrane cartridge of Comparative Example 3 are as shown in Table 1.

(Comparative Example 4)
The peripheral edge of the flat membrane cartridge is made 2.0 mm higher than the center, and the space ratio: 64.0%, opening: opening: 4.00 mm (vertical), 4.00 mm (horizontal) resin mesh: A flat membrane cartridge having the same configuration as in Example 1 was prepared except that Co., Ltd. was used. Details of the flat membrane cartridge of Comparative Example 4 are as shown in Table 1.

(Comparative Examples 5, 6, and 7)
Non-woven fabric having a basis weight of 5 g / m ² and a thickness of 0.07 mm (Comparative Example 5), Non-woven fabric having a basis weight of 120 g / m ² and a thickness of 0.68 mm: Toyobo Co., Ltd. Borance 7121P (Comparative Example 6) Produced a flat membrane cartridge having the same structure as in Example 1. Further, a flat membrane cartridge having a similar configuration and using no nonwoven fabric as a cushioning material (Comparative Example 7) was also prepared. Details of the flat membrane cartridges of Comparative Examples 5, 6, and 7 are as shown in Table 1.

(Comparative Example 8)
A flat membrane cartridge having the same configuration as in Example 1 was prepared, except that the resin mesh was removed and a groove-like flow path was formed on the surface of the membrane support. An example of a flat membrane cartridge having a groove-like channel is shown in JP-A-8-281264 (see FIG. 2). Details of the flat membrane cartridge of Comparative Example 8 are as shown in Table 1.

As is apparent from the results in Table 1, in Examples 1 to 6, flat membrane cartridges having excellent permeation performance are obtained. On the other hand, in Example 7, the height of the central part and the peripheral part in which the resin mesh and the nonwoven fabric were arranged was made larger than 0.5 mm, so that the separation membrane surface was distorted and the membrane permeated water amount was reduced. Moreover, since the level | step difference of a center part and a peripheral part was large, the damage | wound occurred on the surface of the separation membrane.
In Comparative Example 1, as a result of lowering the space ratio of the resin mesh, the variation in the suction pressure distribution in the flow path increased, and the flow volume of the membrane decreased because the flow path space was narrow. In Comparative Example 2, as a result of increasing the space ratio, the variation in the suction pressure distribution in the flow path increased, and the amount of membrane permeated water decreased. In Comparative Example 3, as a result of using a resin mesh having a small mesh opening, the flow path narrowed, the pressure loss increased, and the amount of membrane permeated water decreased. Moreover, in Comparative Example 4, since the mesh of the resin mesh was large, the separation membrane adhered to the resin mesh, and the amount of membrane permeated water was reduced. In Comparative Example 5, as a result of using a nonwoven fabric with a small basis weight and a small thickness, a separation membrane adhered to the resin mesh, and the membrane permeated water flow rate was reduced. In Comparative Example 6, as a result of using a non-woven fabric having a large basis weight and a large thickness, the pressure loss increased and the membrane permeated water amount decreased. In Comparative Example 7, since a non-woven fabric was not used, the separation membrane adhered to the resin mesh and the flow path was narrowed, so that the amount of membrane permeated water was reduced. In Comparative Example 8, the flow channel shape was a groove-like cartridge, and the flow space was narrow, so the amount of membrane permeated water decreased.

The flat membrane cartridge of the present invention is suitable for low-cost and high-efficiency wastewater treatment because it achieves both a reduction in pressure loss and a reduction in the suction pressure distribution on the surface of the separation membrane.

DESCRIPTION OF SYMBOLS 1 Separation membrane 2 Channel material 3 Membrane support plate 4 Peripheral part 5 Center part 6 Buffer material 7 Permeated water intake 11 Submerged membrane cartridge 12 Filter plate 13 Water collecting part 14 Suction nozzle 15 Slit

Claims

Separate the separation membranes along the peripheral edge so as to cover the central part of the membrane support plate with respect to both the front and back surfaces of the resin-made film support plate provided with steps on the front and back surfaces so that the peripheral edge is higher than the central part. Adhesive flat membrane cartridge for wastewater treatment, in which a channel material and a buffer material are arranged in order from the membrane support plate side between the central part of the membrane support plate and the separation membrane, and used as a channel material The resin mesh has an opening of 0.5 to 3.2 mm in both length and width, a wire diameter of 0.4 to 1.0 mm in both length and width, a thickness of 0.6 to 2.0 mm, and a space ratio of 20 to 60%. A flat membrane cartridge for wastewater treatment, wherein the buffer material has a basis weight of 10 to 110 g / m 2 and a thickness of 0.1 to 0.5 mm.
2. The flat membrane cartridge for wastewater treatment according to claim 1, wherein the permeated water flows from the outside of the separation membrane in the order of the buffer material, the channel material, and the permeated water outlet provided at the end of the membrane support plate. .
The flat membrane cartridge for wastewater treatment according to claim 1 or 2, wherein the flow path material is a plain weave type resin mesh and the buffer material is a non-woven fabric.
The peripheral portion of the membrane support plate is 0.6 to 2 mm higher than the central portion, and the height difference between the central portion and the peripheral portion where the flow path material and the buffer material are arranged is 0.5 mm or less. The flat membrane cartridge for wastewater treatment according to any one of 1 to 3.