JP3661206B2 - Immersion membrane separator - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a submerged membrane separator that performs a membrane separation process by immersing a membrane in a liquid, and more particularly to a submerged membrane separator with a buoyant body.
[0002]
[Prior art]
Conventional submerged membrane separation devices generally employ a structure in which a membrane unit is firmly fixed in a tank by a water collecting pipe or a support member. In addition, a cylindrical filtration membrane as a membrane unit is attached to the lower part of the filtration membrane mounting seat, a water chamber is attached to the upper part in a liquid-tight manner by means of attachment screws, etc., and a reverse concave air chamber is formed below the filtration chamber. There is also a structure in which a membrane mounting seat is loaded in a filtration tank and floats by the buoyancy of an air chamber, and a vibration lever provided on the upper surface of the water chamber is moved up and down by an electromagnet to give vibration.
[0003]
[Problems to be solved by the invention]
However, in the conventional immersion type membrane separation apparatus in which the membrane unit is firmly fixed in the tank as described above or connected by a vibration lever, the membrane is exposed to the atmosphere when the liquid level is greatly lowered. May dry out or inhale air and destroy the membrane. Also, the installation work of the membrane unit required a great deal of labor and time.
[0004]
In addition, the conventional membrane separation device that floats the membrane mounting seat with the buoyancy of the air chamber can move the mounting seat up and down somewhat according to the liquid level up and down, but this mounting seat is connected by a vibration lever. Therefore, it cannot follow when the liquid level fluctuates greatly. Moreover, since the upper part of the membrane is exposed to the air, this membrane separation device cannot effectively use the membrane area.
[0005]
Furthermore, when suppressing the formation of the cake layer on the membrane surface by aeration from below the membrane unit, it is desirable to position the membrane unit in the vicinity of the liquid surface with the highest effect of suppressing the cake layer. None of the membrane separation devices can follow the top and bottom of the liquid level, and therefore, an efficient cake layer suppressing effect by aeration could not be expected.
[0006]
Accordingly, an object of the present invention is to provide a submerged membrane separation device in which the membrane unit is always located near the liquid surface following the vertical movement of the liquid surface and the exposure to the air above the membrane is eliminated. It is to do.
[0007]
[Means for Solving the Problems]
The present invention has been proposed in order to achieve the above object, and the invention according to claim 1 is directed to an immersion tank, a membrane unit immersed in the immersion tank, and a buoyancy that floats the membrane unit in a liquid. and body, and a mounting base over scan fixing the該浮force body, a suction pump mounted on the base over the scan with said mounting, a pipe for connecting the membrane unit and the suction pump suction side, the suction pump discharge side An immersion membrane separation device including a provided drainage pipe. The invention according to claim 2 is the submerged membrane separation apparatus according to claim 1, wherein a weight is attached to the lower part of the membrane unit. Further, in the invention according to claim 3, the immersion tank has a separate cylinder standing at the center of the cylindrical water tank, the inside of the cylinder is partitioned as a permeated water tank, and the outside of the cylinder is defined as an annular water tank part, The submerged membrane separation according to claim 1 or 2, wherein a partition plate is provided to form a cleaning unit, and a pipe for discharging water in the cleaning unit and a chemical solution supply pipe to the cleaning unit are provided to immerse the membrane unit. Device. Further, an invention according to claim 4, wherein, provided the different radii arcuate Interrupted guide rails on the upper surface opening portion of the annular water tank unit in a horizontal direction, to constitute a mounting base on the guide rail so as to slide guided claims Item 4. The immersion membrane separation apparatus according to Item 3 . The invention according to claim 5 is the submerged membrane separation apparatus according to any one of claims 3 and 4, wherein a drain pipe provided on the discharge side of the suction pump is passed through a permeate tank in the cylinder.
[0008]
[Action]
By the holding means including the weight of the membrane unit, the entire area of the membrane unit is held in a submerged state under the liquid surface, and as a result, the membrane unit is attached to the buoyant body so as to be under the water surface. As a result, an air lift circulation flow is generated by the air diffused from below the membrane unit, so that the clogging between the membranes can be prevented and the cleaning effect by bubbling is improved. Moreover, since the membrane unit is not fixed to the tank, the membrane unit follows the liquid surface up and down, and the membrane is not exposed to the air and is not hydrophobized. In addition to being able to move vertically in conjunction with the liquid level, it is also possible to move freely in the horizontal direction.
[0009]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
A submerged membrane separation apparatus 1 shown in FIG. 1 is a basic embodiment of the present invention, and a membrane unit 3 is immersed in the immersion tank 2 in a state of being floated by the buoyancy of a buoyant body 4. The membrane unit 3 is, for example, a submerged flat membrane, a hollow fiber membrane, or a unit thereof, and has two buoyant bodies 4 on the upper part, so that the membrane unit 3 is always levitated near the liquid surface, and the liquid level changes. The position can be changed according to the condition.
[0010]
The buoyancy body 4 has an appropriate shape such as a sphere or a polyhedron, but has a large volume compared to its own weight, for example, by hollowing the inside or filling with foamed polystyrene. The buoyancy body 4 may have any shape and structure as long as the buoyancy body 4 can give sufficient buoyancy to the membrane unit 3, and the number of attachments is not limited.
[0011]
Reference numeral 5 denotes a connecting member that connects the membrane unit 3 and the buoyant body 4. As the connecting member 5, a flexible member such as a strip or a member integrated with the membrane unit 3 by a rigid structure is appropriately used. You may select and use. Further, the distance between the buoyancy body 4 and the upper end of the membrane unit 3 can be freely set, and it is sufficient that the upper end of the membrane does not protrude from the liquid surface into the air.
[0012]
Two buoyancy bodies 4 provided on the upper part of the membrane unit 3 are fixed to a plate-like mounting base 6. A suction pump 7 is mounted on the mounting base 6, and a suction side pipe of the suction pump 7 is mounted. 8 is connected to the membrane unit 3 as a water collecting pipe, and a drain pipe 9 with a flexible tube is connected to the discharge side on the discharge side, and suction filtration is performed using the water depth difference of the membrane unit 3 and the suction force of the suction pump 7. The permeated water that has passed through the membrane of the membrane unit 3 is collected by the pipe 8 and drained from the drain pipe 9.
[0013]
Also, a weight 10 is suspended below the membrane unit 3 as one component of a holding unit that immerses the membrane surface of the membrane unit 3 under the liquid level over the entire area. This is a case where the weight of the membrane unit 3 is light relative to the volume, that is, the specific gravity is light. A weight 10 is attached under the membrane unit 3 with the buoyant body 4 so that the membrane surface does not float in the atmosphere. It is. Therefore, even when the weight 10 is not attached, the weight of the membrane unit 3 itself serves as the holding means.
[0014]
As shown in FIG. 2, the membrane unit 3 floating below the liquid surface by such a configuration moves in the vertical direction in conjunction with the vertical movement of the liquid surface level in the immersion bath 2, or easily in the horizontal direction. Or move. In addition, since the diffuser pipe 11 which comprises a part of aeration apparatus is arrange | positioned under the membrane unit 3, the air sent from the blower 12 is sent in a liquid from the diffuser pipe 11, and by this bubble, The cake layer growing on the film surface of the film unit 3 can be peeled off. Further, even if the membrane unit 3 moves in the vertical direction or the horizontal direction according to the level of the liquid level, a flexible tube is interposed in the middle of the drain pipe 9, and the pipe is bent sufficiently. Therefore, there is no trouble in draining the permeated water from the membrane unit 3.
[0015]
Moreover, according to the present Example, it is not necessary to provide the fixing member with respect to the tank 2, and since there is no component embedded in the immersion tank 2, maintenance management is easy. And by attaching the buoyancy body 4, the membrane unit 3 can be positioned under a certain water level even under conditions where the liquid level varies.
[0016]
By aeration from the air diffuser 11 below the membrane unit 3, the membrane filtration in the bubble rising airflow can suppress the formation of the cake on the membrane surface and is the most efficient, and the membrane unit is placed in the water tank where the water level fluctuates. The relative position of the membrane unit 3 varies depending on the water level under the condition that the 3 is buried and fixed, but if the membrane unit 3 is installed near the water surface where the suppression effect of the cake layer is highest as in this embodiment, the buoyancy of the buoyant body The membrane unit 3 can be positioned under conditions where there is always destruction of bubbles and accompanying vibration of water. Therefore, the cake layer hardly grows on the membrane surface, which is suitable for suction membrane filtration. Moreover, since it has such an effect, it is suitable for the use conditions which carry out membrane filtration over 24 hours on the use conditions which discharge | emit only in the daytime period.
[0017]
Furthermore, since the suction pump 7 is provided on the mounting base of the buoyant body 4, the suction pump 7 is fixed on the land, piped to the membrane unit 3 that is far away, and a conventional membrane separation device that performs suction filtration. In comparison, the efficiency can be increased. That is, as the suction pipe becomes longer, the pipe resistance increases and the true suction filtration pressure in the membrane unit 3 is reduced. However, if the suction pump 7 is arranged on the upper part of the membrane unit 3 as in this embodiment, the suction pipe is always provided. The pipe resistance can be kept small. Therefore, membrane filtration can be performed efficiently.
[0018]
In addition, when obtaining purified water without turbidity by membrane filtration from a lake or the like, it is preferable because only water with low turbidity concentration near the water surface can be separated. In other words, it is advantageous in that coarse particles that hinder membrane filtration are precipitated by natural sedimentation, and only the most turbid and diluted target water is always subjected to filtration.
[0019]
As described above, the membrane unit 3 can be moved horizontally under conditions above a certain water level, and the membrane module can be moved and cleaned using this, and the movement in the horizontal direction and the vertical direction can be combined to the washing water tank. Can be moved automatically. Examples thereof will be described below.
[0020]
3 to 11 show an embodiment in which a plurality of submerged membrane separators 1 having the above-described basic configuration are provided. Each submerged membrane separator 1a to 1f is not only moved in the vertical direction but also in the horizontal direction. It can move and is configured to move manually or automatically to a washing water tank 14 formed at one location in the cylindrical water tank 13.
[0021]
FIG. 3 is a plan view of the cylindrical water tank 13, and FIG. 4 is an AA cross-sectional view of the water tank 13. The cylindrical water tank 13 is provided with a separate cylinder at the center to define the inside of the cylinder as a permeated water tank 15, and the outside of the cylinder as an annular water tank part 16, and an annular water tank part around the permeated water tank 15. 16, two partition plates 17 are arranged at a predetermined interval in the circumferential direction as shown in the figure, and are extended from the bottom of the water tank 13 to the height of the lower half, so that one submerged membrane separation is performed. A cleaning water tank 14 capable of storing the apparatus 1 is partitioned. In the annular water tank section 16, a plurality of, in this embodiment, six submerged membrane separation devices 1 are arranged at equal intervals in the circumferential direction.
[0022]
5 and 6 show the positional relationship of each of the submerged membrane separators 1 during high water level operation. The six submerged membrane separators 1a to 1f are arranged in a water tank above the partition plate 17. A drainage pipe 9 a made of a flexible tube from the suction pump 7 passes through a permeate tank 15 in the center. Therefore, all of the permeated water filtered by the membrane units 3 of the submerged membrane separators 1a to 1f is once collected in the permeated water tank 15 through the drain pipe 9a, and is separately collected from the permeated water tank 15 through a separate pipe. Drained. In FIG. 5, the partition plate 17 is represented by a dotted line to indicate that the partition plate 17 is below the water surface.
[0023]
Further, as shown in FIGS. 7 and 8, a circular arc-shaped guide rail 18 having a different radius is provided in the upper surface opening of the annular water tank portion 16 in the horizontal direction, and each submerged membrane separation device 1 is provided on the guide rail 18. The mounting base 6 is slidably guided. The means for moving the six submerged membrane separation devices 1 in the annular water tank 16 in the horizontal direction may be manually operated, but a rotating arm that presses the mounting base of each submerged membrane separation device 1 (FIG. (Not shown) is preferably configured so that it can be moved mechanically, for example, by providing it in the radial direction of the annular water tank section 16.
[0024]
Next, the cleaning automation process in the apparatus having the above-described configuration will be described.
[0025]
As shown in FIG. 6, when each submerged membrane separator 1 is operated at a high water level, the water level is reduced by the amount of permeated water that has been membrane-filtered, and each submerged membrane separator 1a is reduced as the water level decreases. ˜1f gradually descends with the liquid level. Therefore, as shown in FIGS. 9 and 10, the positional relationship of the membrane unit 3 changes to that at the time of low water level operation.
[0026]
During operation at a low water level, the water level drops from the upper ends of the partition plates 17 and 17, so that one submerged membrane separation device 1 a located above the partition plate 17 has two partition plates 17 and 17. Trapped by between. And between the partition plates 17 and 17 is used as the washing water tank 14, the submerged membrane separation apparatus 1a is washed, and the remaining membrane separation apparatuses 1b to 1f perform the filtration operation.
[0027]
Cleaning of the submerged membrane separation apparatus 1a stops the pump, and opens the opening / closing valve 20 of the drain pipe 19 connected to the partition bottoms of the partition plates 17 and 17 of the cleaning water tank 14, as shown in FIG. The concentrated water in 14 is discharged.
[0028]
Next, a chemical solution is put into the washing water tank 14. In introducing the chemical solution, the chemical solution can be prepared by using the permeated water tank 15. That is, as shown in FIG. 11, an insole 23 is provided at a position higher than the upper end of the partition plate 17 in the permeate tank 15 in the center, and the top from the insole is a chemical solution adjusting tank 15 a, and an open / close valve is provided in the insole 21, the on-off valve 21 is normally opened, and the permeated water that each of the submerged membrane separators 1 a to 1 f drains into the permeate tank 15 through the drain pipe is introduced to the bottom of the insole through the on-off valve 21. Drain from the bottom. When cleaning the membrane separation device 1a, the on-off valve 21 is closed, and the permeated water discharged from the devices 1b to 1f is adjusted with the chemical solution while the on-off valve 20 of the drain pipe is opened to drain the concentrated water in the washing water tank. When a predetermined amount of water is stored in the tank 15a, chemicals are added thereto to adjust the cleaning liquid, the valve 22 of the supply pipe 24 to the cleaning water tank 14 provided immediately above the inner bottom is opened, and the cleaning liquid is supplied to the cleaning water tank 14. When the supply of the cleaning liquid to the cleaning water tank is finished, the on-off valve 21 is opened and the valve 22 is closed.
[0029]
Thus, the membrane surface of the membrane unit 3 is washed by immersing the membrane separation device 1a in the chemical solution in the washing water tank for a certain period of time, and after sufficiently washing, the washing water is discharged from the drain pipe 19, and then the raw water is removed. Replenish and return to the state during high water level operation (Fig. 6).
[0030]
The six submerged membrane separators 1a to 1f are swung to 60 ° in a fixed direction, and the submerged membrane separator 1b to be cleaned next is positioned on the partition plate 17,17. The interrupted guide rail 18 described above guides each membrane separation device 1a to 1f to guide to the interrupted interval of the rail which is the next turning position. In addition, the partition of the partition plates 17 and 17 is provided in one downward direction of the space | interval which the rail interrupted (refer FIG. 7).
[0031]
By repeating the above process, the other submerged membrane separation apparatus 1b is also cleaned in the same manner when the other apparatuses 1a and 1c to 1f are operated at a low water level. In this way, one membrane separator is sequentially cleaned at the time of low water level operation.
[0032]
As described above, in this embodiment, a plurality of submerged membrane separators 1a to 1f are annularly arranged and floated in a cylindrical water tank 13, and each submerged membrane separator 1 is moved only in the vertical direction. In addition, the water tank 13 can be moved in a horizontal direction, and a sector which becomes a washing water tank 14 is partitioned by a partition plate 17 at a height at which the submerged membrane separation device 1 is accommodated in the lower part of the water tank 13. When necessary, the submerged membrane separator 1 can be transferred to the washing water tank 14 in the water tank 13 in order and to the one, so that the membrane surface can be cleaned very easily and automatically.
[0033]
The submerged membrane separation apparatus 1 according to the present invention is not limited to those provided in a reaction tank, a dipping tank, or the like, but can be used in a form that is immersed in the natural world such as lakes, seawater, and rivers. it can. For example, it can be provided in a water intake source such as a water purification plant or a factory.
[0034]
【The invention's effect】
As described above, according to the present invention, the whole area of the membrane unit is held under the liquid level by the holding means, and as a result, the whole membrane unit is attached to the buoyant body so as to be under the water surface. An air lift circulation flow is generated by air diffusion from the lower part, blocking between the membranes can be prevented, and the cleaning effect by bubbling is improved. Further, since the membrane unit is not fixed to the tank, it follows the top and bottom of the liquid level, the membrane surface is not exposed to the air, and is not hydrophobized. In addition to being able to move vertically in conjunction with the liquid level, it is also possible to move freely in the horizontal direction.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a first embodiment of a submerged membrane separation apparatus showing a basic configuration of the present invention.
FIG. 2 is an explanatory diagram showing the movement of a membrane unit accompanying water surface fluctuations.
FIG. 3 is a plan view of a water tank in a second embodiment for floating a plurality of submerged membrane separation devices.
4 is a cross-sectional view taken along the line AA of the water tank of FIG. 3. FIG.
5 is a plan view showing a state at the time of high water level operation in a form in which a plurality of submerged membrane separation devices are annularly arranged in the water tank of FIG. 3;
6 is a BB cross-sectional view of the water tank of FIG.
FIG. 7 is a plan view of a water tank showing the arrangement of guide rails.
FIG. 8 is a perspective view showing a positional relationship between a guide rail and a submerged membrane separation device.
FIG. 9 is a plan view showing a state during low water level operation.
10 is a cross-sectional view of the water tank of FIG. 9 taken along the line BB.
FIG. 11 is a cross-sectional view of the water tank showing a state when the cleaning water tank is drained.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Submerged membrane separator 2 Immersion tank 3 Membrane unit 4 Buoyant body 5 Connecting member 6 Mounting base 7 Suction pump 8 Pipe 9 between the suction pump and the membrane unit Drain pipe 10 Weight 11 Aeration pipe 12 Blower 13 Cylindrical water tank 14 Washing water tank 15 Permeated water tank 15a Chemical solution adjusting tank 16 Annular water tank part 17 Partition plate 18 Guide rail 19 Drain pipe 20 Opening / closing valve 21 Opening / closing valve 22 Closing open / close valve 23 Middle bottom 24 Supply pipe

Claims (5)

An immersion tank, a membrane unit immersed in the immersion tank, a buoyant body that floats the membrane unit in a liquid, a mounting base that fixes the buoyant body, and a mounting base mounted on the mounting base a suction pump, and piping connecting the the membrane unit suction pump suction side, submerged membrane separator including the provided suction pump discharge side drain pipe.   The submerged membrane separator according to claim 1, wherein a weight is attached to a lower portion of the membrane unit.   The immersion tank has a separate cylinder standing at the center of the cylindrical water tank, the inside of the cylinder is divided as a permeated water tank, the outside of the cylinder is defined as an annular water tank part, a partition plate is provided in the annular water tank part, and becomes a cleaning part, The submerged membrane separation apparatus according to claim 1 or 2, wherein a pipe for discharging water in the cleaning unit and a chemical solution supply pipe to the cleaning unit are provided, and the membrane unit is immersed. The submerged membrane separation device according to claim 3, wherein a guide rail having an arc-like shape with different radii is provided in a horizontal direction at an upper surface opening of the annular water tank portion, and a mounting base is slidably guided on the guide rail. The submerged membrane separation apparatus according to any one of claims 3 and 4, wherein a drain pipe provided on the discharge side of the suction pump is passed through a permeate tank in a cylinder.

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