JP2007268415A - Immersion type membrane separation apparatus and water producing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an immersion type membrane separation apparatus which carries out uniform and stable cleaning to each membrane element and exhibits an excellent performance about whole processing amount and maintenance cost, and also to provide a water production method using the same. <P>SOLUTION: The immersion type membrane separation apparatus has a case body in which a plurality of membrane elements are arranged and stored with the direction of a membrane surface parallel to a vertical direction inside and a membrane module having an aeration device at a position below the case body. A plurality of straightening vanes are extended in a pair in the direction in which the membrane surface of the membrane element turns orthogonal to a surface direction of the straightening vane outside the case body. The immersion type membrane separation apparatus has external aeration devices having an aeration function in a position outside the case body in the direction orthogonal to the direction of the membrane surface of the membrane element. The water production method uses the immersion type membrane separation apparatus. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a submerged membrane separation device suitable for use in wastewater treatment and water purification treatment using membrane separation technology, and a water production method using the separation device.

  Membrane separation technology is a technology that has become widespread while expanding its application fields because it has features such as energy saving, space saving, power saving, and product quality improvement. Membrane separation methods include methods such as reverse osmosis, ultrafiltration, and microfiltration, and filtration membranes in the form of hollow fiber membranes, flat membranes, tubular membranes, etc. are used. As this application field, it has been used for seawater desalination, water purification, gas separation, blood purification, etc., but recently, from the viewpoint of environmental conservation, research to apply membrane separation technology to wastewater treatment is also available. It is being advanced.

  When membrane separation technology is applied to wastewater treatment, the membrane module is immersed in a water tank filled with wastewater such as activated sludge, and the permeate side of the module is treated using a water level difference such as pump suction or siphon. A technique using an immersion film for obtaining water is known. At this time, in the activated sludge treatment, since aeration is usually carried out in order to breed aerobic microorganisms in the aquarium, when a module constituted by interpolating a plurality of elements in the aquarium is immersed and used. The solid-liquid separation can be performed while removing the dirt on the membrane surface by the swirling flow formed in the water tank by aeration, and operation at a very low cost is possible.

  For example, in a water treatment apparatus for treating organic wastewater, a membrane module 3 for membrane-separating the water to be treated 2 is installed inside the treatment tank 1 as shown in FIG. In the membrane module 3, a plurality of membrane elements 5 having membranes installed on both sides of a support plate made of plastic, stainless steel, or the like are loaded into a casing 4 that is open at the top and bottom, and the membrane elements 5 are transmitted through the casing. A liquid collecting pipe 6 connected to a nozzle for water intake and a diffuser pipe 8 for introducing air into the housing are provided.

  At this time, the air supplied by the blower 7 is diffused through the diffuser holes of the diffuser 8, and the bubbles of the diffused air and the ascending water flow caused thereby are caused to flow into the gaps between the membrane elements 5. The membrane surface of the membrane element 5 is cleaned by the ascending water flow. However, the ascending water flow passing through the housing 4 causes a swirling flow parallel to the membrane surface of the membrane element 5 and at the same time, Since a swirling flow in a direction perpendicular to the membrane surface occurs at the same time, in the vicinity of the air diffuser 8 installed in the lower portion of the casing 4, the flow gathers in the center of the casing 4, so that in the membrane element 5 loaded in the casing 4 A difference occurs in the flow rate of the upward flow between the membrane element 5 loaded in the central portion of the casing 4 and the membrane element 5 loaded in the end portion of the casing 4.

  As a result, the membrane surface of the membrane element 5 has a difference in the cleaning effect of the membrane surface of the membrane element 5 due to the difference in the loading location / position of the housing 4, and a uniform flow rate cannot be obtained for each membrane element. In other words, there is a problem that the entire treatment amount (in the case of fresh water generation equipment, the total amount of fresh water) decreases.

  In order to eliminate such a difference in the flow velocity of the upward flow, it has been proposed to provide a rectifying plate having a rectifying function on the upper part of the membrane module (Patent Document 1-2).

  In addition, there has been proposed a membrane separation device in which the fine bubble diffusing device is arranged in a region parallel to the flat membrane on the side of the membrane unit (Patent Document 3).

However, these proposals all have room for improvement in terms of rectifying action and effect according to the study by the present inventors, and obtain a uniform cleaning effect and a uniform flow rate for each membrane element. Therefore, it was understood that it was still necessary to examine the overall arrangement of the equipment including the diffuser.
JP-A-8-332358 Japanese Patent No. 3290577 JP 2005-87830 A

  In view of the above-mentioned points, the present invention provides a submerged membrane separation apparatus that can perform uniform and stable cleaning on each membrane element and can exhibit excellent performance as an overall throughput. An object of the present invention is to provide a fresh water generation method using a submerged membrane separator.

  More specifically, the present invention eliminates the swirl flow that occurs in the direction perpendicular to the membrane surface direction of the membrane element by performing aeration outside the housing in a direction perpendicular to the membrane surface of the membrane element. By eliminating gathering of swirling flow to the center near the air diffuser installed at the bottom of the housing, an upward flow due to air diffusion is caused evenly for any membrane element installed in the housing. It is an object of the present invention to provide a submerged membrane separation apparatus capable of improving the cleanability of the surface, and a water production method using the submerged membrane separation apparatus.

  The submerged membrane separation apparatus of the present invention that achieves the above-described object has the following configuration (1).

(1) A casing in which a plurality of membrane elements are arranged and stored in the casing so that the membrane surface direction thereof is parallel to the vertical direction, and an air diffuser installed at a position below the casing. In a submerged membrane separation apparatus having a membrane module, a plurality of rectifying plates are paired outside the casing by extending downward in a direction in which the membrane surface direction of the membrane element and the rectifying plate surface direction are perpendicular to each other. And an outer air diffuser having an air diffuser function at a position outside the housing under a direction perpendicular to the membrane surface direction of the membrane element. .

  In addition, in the immersion type membrane separation apparatus of the present invention, more specifically, the following (2) to (4) is preferable.

(2) The submerged membrane separation apparatus according to (1), wherein the rectifying plate is provided to extend to the outside of the casing with a length of 30 cm or more from the outer end position of the casing.

(3) The submerged membrane separation apparatus according to (1) or (2), wherein the rectifying plate and the outer wall of the housing are configured as an integral structure.

(4) The immersion according to (1), (2) or (3) above, wherein the diffuser installed at the lower position of the housing and the outer diffuser are configured as an integral structure. Mold membrane separator.

(5) The submerged membrane separation apparatus according to the above (1), (2), (3) or (4), which is a waste water or water purification apparatus.

  Moreover, the fresh water generation method of the present invention that achieves the above-described object has the following configuration (6).

(6) A fresh water production method characterized in that water is produced from raw water to be treated using the immersion membrane separator according to (1), (2), (3), (4) or (5).

  According to the submerged membrane separation apparatus of the present invention, air bubbles diffused from the diffuser tube in the lower part of the casing and the rising water flow caused thereby pass through the gap between the membrane elements and exit the casing. Later, a swirling flow that flows in the horizontal direction with respect to the membrane surface direction is caused, and an even upward flow can be caused for each membrane element loaded in the casing. Surface cleaning can be performed.

  The longer the rectifying plate is extended to the outside along the housing, the more the swirl flow that occurs in the direction perpendicular to the membrane direction of the membrane element is eliminated and the swirl flow in the horizontal direction of the membrane element is more likely to occur. By providing a rectifying plate extending to the outside with a length of 30 cm or more, it is possible to cause a more reliable and even upward flow for each membrane element loaded in the housing. Become more prominent.

  According to the present invention, good and uniform membrane surface cleaning can be performed on the total number of each membrane element, and an equal amount of treated water can be obtained in each membrane element. As a result, stable operation over a long period of time becomes possible, and maintenance labor and costs can be reduced by reducing the frequency of backwashing and chemical washing of the membrane element.

Hereinafter, the present invention will be described in more detail based on an embodiment example shown in the drawings.
The submerged membrane separation apparatus of the present invention includes a housing 4 in which a plurality of membrane elements 5 are arranged and housed inside the housing 4 so that the membrane surface direction is parallel to the vertical direction, and the housing. In the submerged membrane separation apparatus having a membrane module having a diffuser 8a installed at a position below 4, the membrane surface direction of the membrane element and the rectifying plate surface direction are perpendicular to the outside of the housing. An outer air diffuser having a plurality of current plates 9a, 9b extending in the direction downward and having an air diffuser function at a position outside the housing 4 in a direction perpendicular to the film direction of the membrane element 1 and FIG. 2, the membrane module 3 provided by being immersed in the water to be treated 2 in the treatment tank 1 is the same as that of FIG. It is configured in almost the same way.

  The housing 4 is not particularly limited in terms of structure, as long as it can accommodate a plurality of membrane elements 5 arranged therein and has the liquid collection pipe 6 positioned on the side edge. However, the plurality of (preferably, 50 to 200) membrane elements 5 (preferably 50 to 200 because the effect of the present invention can be more exerted) can be stacked at regular intervals in the horizontal direction, and the upper and lower surfaces of the housing 4 A shape in which is released is preferred.

  The distance between the membrane surfaces of the plurality of membrane elements 5 housed in the housing 4 is not particularly limited, but one having an interval of 5 to 20 mm can exhibit more effect. The size of the membrane element 5 stored in the housing 4 is not particularly limited, but when the membrane element 5 having a length of 0.5 to 2 m in the vertical direction is arranged and stored in the housing 4 The present invention is more effective.

  An air diffuser 8a for discharging air is provided at the lower part of the membrane module 3, but the air diffuser 8a may be fixed to the housing 4 or installed separately from the housing 4. May be. The arrangement and form of the air diffuser 8a are not particularly limited, and any arrangement may be used as long as air can be uniformly fed to the plurality of membrane elements 5 and air diffuser holes are provided.

  Here, the submerged membrane separator of the present invention is different from the conventional one in that the rectifying plates 9a and 9b are paired outside the housing 4 in a direction perpendicular to the membrane surface direction of the membrane element 5. The outer diffuser 8b, 8c is provided outside the housing 4 in a direction perpendicular to the film surface direction.

  It is preferable that the rectifying plate 9 has a length of 30 cm or more from the outer end position of the housing 4 and is fixed and installed on the bottom surface 1a or the side surface 1b of the processing tank 1, and a position of 30 cm to 100 cm is more preferable. . The rectifying plates 9a and 9b can also be provided as an integral structure with the housing 4 (outer wall), which makes it easy to install the submerged membrane separation apparatus.

  The form of the air diffuser 8b and 8c which diffuses in the outer position of the housing | casing 4 under the direction perpendicular | vertical to the film | membrane surface direction of the air diffuser 8a and the membrane element 5 arrange | positioned at the lower part of the housing | casing 4 is especially limited. Is not to be done. In particular, the outer air diffusers 8b and 8c installed outside the housing 4 may be integrated with the air diffuser 8a disposed in the lower portion of the housing. Installation is easy.

  FIG. 4 shows the present invention in which the rectifying plate 9 is integrated with the housing 4 (outer wall), and the outer air diffuser installed outside the housing 4 and the air diffuser arranged below the housing are integrated. It is the schematic model perspective view which showed 2nd Embodiment of this immersion type membrane separator.

  In this embodiment, the form of the air diffuser 8 is not particularly limited. As an example, as illustrated in FIG. 4, one or a plurality of pipes are arranged below the membrane module, and this pipe It is also possible to provide diffused holes at regular intervals on the upper surface. In this example, the number and size of the diffuser holes are not particularly limited, and can be appropriately set according to the amount of air.

  In the submerged membrane separation apparatus configured as described above, as shown in FIG. 1, the water to be treated such as waste water is separated from the water 2 to be treated by the membrane element 5 by the suction force of the filtered water extraction means 10 such as a pump. Membrane separation can be performed. At this time, suspended substances such as microbial particles and inorganic substance particles contained in the water to be treated are filtered. On the other hand, in parallel with the filtration, the air diffusers 8a, 8b, 8c generate bubbles, and the upward flow parallel to the membrane surface direction of the membrane element 5 generated by the air lift action of the bubbles causes the filtrate deposited on the membrane surface. Let go.

  At this time, the rising water flow and the bubbles that have passed through the gap between the membrane elements 5 cause a swirling flow in the treatment tank 1 after exiting the housing 4, but are diffused outside the housing 4 by the air diffusers 8 b and 8 c. Further, it is possible to eliminate the swirling flow that occurs in the direction perpendicular to the membrane surface direction of the membrane element 5 by installing the rectifying plate 9 having a length of preferably 30 cm or more. Can be uniformly dispersed on the membrane surface of each membrane element 5, and the membrane surface can be efficiently and evenly washed.

  As a result, each membrane element can obtain a uniform amount of treated water, can be operated stably for a long time, and the frequency of backwashing and chemical washing of the membrane element 5 can be reduced.

  Such an apparatus of the present invention can be used very well as a wastewater treatment apparatus or a water purification apparatus.

  Using the submerged membrane separation apparatus of the present invention, according to the fresh water generation method of the present invention for producing water from the raw water to be treated, a longer period of stable operation is possible under a larger amount of treated water, Further, it is possible to reduce the frequency of backwashing and chemical washing of the membrane element.

FIG. 1 is a schematic model cross-sectional view showing the entire configuration of a processing tank in which an immersion membrane separation apparatus according to an embodiment of the present invention is installed. FIG. 2 is a schematic model plan view of the submerged membrane separation apparatus according to the embodiment of the present invention shown in FIG. FIG. 3 is a schematic model explanatory diagram showing the overall configuration of a processing tank in which a conventional immersion membrane separation apparatus is installed. FIG. 4 is a schematic model perspective view showing a second embodiment of the submerged membrane separation apparatus according to the present invention.

Explanation of symbols

1: Treatment tank 2: Water to be treated 3: Membrane module 4: Housing 5: Membrane element 6: Liquid collecting tube 7: Blower 8, 8a: Air diffuser 8b, 8c: Outer air diffuser 9, 9a, 9b 9c, 9d: Rectifying plate 10: Filtration water extraction means such as a pump

Claims (6)

  The housing has a housing in which a plurality of membrane elements are arranged and stored so that the membrane surface direction is parallel to the vertical direction, and an air diffuser installed at a position below the housing. In a submerged membrane separation apparatus having a membrane module, a plurality of rectifying plates are installed in pairs outside the casing so that the membrane surface direction of the membrane element and the rectifying plate surface direction are perpendicular to each other. In addition, the submerged membrane separation device is characterized in that an outer air diffuser having an air diffuser function is installed at a position outside the casing in a direction perpendicular to the membrane surface direction of the membrane element.   2. The submerged membrane separation apparatus according to claim 1, wherein the rectifying plate is provided to extend outside the casing with a length of 30 cm or more from the outer end position of the casing.   3. The submerged membrane separation apparatus according to claim 1, wherein the current plate and the outer wall of the casing are formed as an integral structure.   4. The submerged membrane separation apparatus according to claim 1, 2, or 3, wherein an air diffuser and an outer air diffuser installed at a lower position of the casing are configured as an integral structure.   The submerged membrane separator according to claim 1, 2, 3, or 4, wherein the submerged membrane separator is a waste water or water purification apparatus.   A fresh water production method comprising producing water from raw water to be treated using the submerged membrane separation apparatus according to claim 1, 2, 3, 4 or 5.

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