JPH0824855A - Immersion type membrane separator - Google Patents

Abstract

PURPOSE:To certainly perform treatment such as aeration treatment or precipitation treatment and keeping transmission flow velocity high by a simple structure to perform efficient transmission while easily performing the washing work of membrane surface. CONSTITUTION:A first liquid tank 12 in which a raw soln. is stored and a second liquid tank 14 in which a membrane element 13 are immersed are provided and an overflow pipe 17 allowing the raw soln. in the second liquid tank to overflow to the first liquid tank is provided between both tanks 12, 14 and the suction side of a circulating pump 18 is connected to the first liquid tank while the pipe 23 connected to the emitting side of the circulating pipe 18 is arranged in the lower part of the membrane element of the second liquid tank.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention utilizes a water head difference based on the water depth in a dipping tank in which a membrane element is dipped, and a suction pump is used to perform membrane separation at low energy to obtain permeated water. The present invention relates to a separation device, which is particularly adapted to efficiently perform aeration treatment and coagulation sedimentation treatment.

[0002]

2. Description of the Related Art Immersion type membrane separators are known in which membrane elements are provided in a biological treatment tank or a precipitation tank in which air is blown into a stock solution to decompose organic pollutants by the action of microorganisms. For example, in the conventional submerged membrane separation apparatus shown in FIG. 4, the membrane element 2 is directly immersed inside the reaction tank 1, and the membrane element 2 is provided inside the reaction tank 1 in order to provide a membrane surface velocity and to circulate and stir the reaction mixture. The air diffuser 3 is provided. Further, as shown in FIG. 5, the dipping tank 4 for dipping the membrane element 2 and the reaction tank 1 are provided by being partitioned by a partition wall 5, and the dipping tank 4 is dipped from the reaction tank 1 by an overflow channel 6 formed on the partition wall 5. The reaction liquid overflows into the tank 4 and the liquid in the immersion tank 4 is discharged as it is by the operation of the pump 7, or the reaction tank 1
It will be returned to.

[0003]

The conventional immersion type membrane separation device shown in FIG. 4 is compact because the device is not bulky, but has a high risk of separating soluble components such as BOD and COD. Unreacted components flow out to the permeate side.

Further, the conventional immersion type membrane separation device shown in FIG. 5 is excellent in stability because unreacted components rarely flow out to the permeation side, but it is a high membrane to maintain a high permeation flow rate. Since it is necessary to provide a surface flow velocity, an air diffuser 8 must be additionally provided below the membrane element.

Further, in the membrane separation device, the membrane surface must be washed. When performing the membrane surface cleaning operation, the membrane element 2 is pulled out from the immersion tank or is directly washed in the immersion tank. I have to do it. However, in the above-mentioned conventional membrane separation device, when directly washing in the immersion tank, it is necessary to provide a separate water tank and transfer the reaction liquid in the immersion tank to this water tank. Must also be prepared.

Therefore, according to the present invention, the treatment such as aeration treatment and precipitation treatment can be surely performed, the permeation flow velocity can be kept high with a simple structure, and efficient permeation can be performed. It is an object of the present invention to provide an immersion type membrane separation device that can be easily washed.

[0007]

The present invention has been proposed in order to achieve the above-mentioned object, and a first liquid tank for storing a stock solution and a second liquid tank in which a membrane element is immersed are provided to provide a first liquid. An overflow channel is provided between the tank and the second liquid tank to allow the stock solution of the second liquid tank to overflow into the first liquid tank, and the discharge side pipe of the circulation pump, whose suction side is connected to the first liquid tank, is provided as a second pipe. It is arranged below the membrane element of the liquid tank.

[0008]

Operation The stock solution in the first liquid tank is discharged from the discharge port toward the membrane element by the operation of the circulation pump. Therefore, a water flow is generated in the flow path between the membrane elements due to this discharge flow, and the membrane surface flow velocity is increased, whereby the permeation flow velocity is maintained high and efficient membrane separation is performed, and the membrane surface flow velocity is not necessarily increased. Is not required, and if diffused, the membrane surface flow velocity is further increased by the synergistic effect of the discharge flow and the diffused water flow.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. The immersion type membrane separation apparatus 1 shown in FIG. 1 is for aerating an undiluted solution to perform membrane separation, and a first liquid tank 12 for storing the undiluted solution and a second liquid tank 1 for immersing the membrane element 13.
First liquid tank 12 provided separately from 4 and functioning as a reaction tank
An aeration pipe 15 is arranged inside, an aeration port 15 ′ at the tip is arranged near the bottom, and an overflow pipe 17 is connected to an overflow outlet 16 opened at the upper part of the second liquid tank 14 to connect the overflow pipe 17 with the overflow pipe 17. The outlet faces the first liquid tank 12 upward.

That is, an overflow passage is provided between the first liquid tank 12 and the second liquid tank 14 to allow the stock solution of the second liquid tank 14 to overflow into the first liquid tank 12, and both liquid tanks 12, 14 are provided.
Connect. Further, the discharge side pipe of the circulation pump 18 whose suction side is connected to the first liquid tank 12 is arranged below the second liquid tank 14, and the discharge port 19 is installed facing the membrane element 13.
Specifically, the suction port of the circulation pump 18 is connected to the stock solution outlet 20 provided in the lower portion of the first liquid tank 12, and the stock solution delivery pipe 21 extending from the discharge port of the circulation pump 18 is connected to the second solution tank 14. The undiluted solution inlet 22 is connected to the undiluted solution inlet 22 provided on the lower side surface.
The pipe 23 is arranged along the bottom of the second liquid tank 14, and the discharge port 19 formed upward at the tip of the pipe 23 is installed toward the membrane element 13 located above.

The membrane element 1 is provided in the second liquid tank 14.
Since 3 are arranged side by side at a predetermined interval and soaked,
A pipe 23 is passed under the membrane element rows along the juxtaposed direction of the membrane elements 13, a plurality of discharge ports 19 are opened in the middle of the pipe 23, and each discharge port 19 is a flow path between the upper membrane elements 13. It is desirable to turn to.

In this way, the first liquid tank 12 and the second liquid tank 14
If the overflow pipe 17 and the undiluted solution delivery pipe 21 are connected to each other, the undiluted solution in the first liquid tank 12 is
Is delivered to the second liquid tank 14 via the first liquid tank 1 again via the overflow pipe 17.
A circulation channel returning to the inside of 2 is formed.

The second liquid tank 14 which also functions as a dipping tank
Inside, the air diffuser 24 is arranged below the membrane element row,
The air outlet 25 of the air diffuser 24 is connected to the upper membrane element 1
Open for 3.

Immersion type membrane separation apparatus 1 having such a structure
In the above, when air is sent into the first liquid tank 12 through the aeration pipe 15, this air is released from the aeration port 15 'into the stock solution, whereby oxygen is replenished in the stock solution and the action of microorganisms is promoted. As a result, the decomposition of organic pollutants is accelerated. Also,
When air is released from the aeration port 15 ', the air becomes bubbles and rises in the stock solution, so that the rise of the bubbles stirs the stock solution and further promotes the decomposition of organic pollutants. Therefore, the efficiency of the aeration process can be improved.

The stock solution (reaction solution) which has been aerated in the first solution tank 12 is operated by the circulation pump 18 to supply the stock solution delivery pipe 2.
It is pressure-fed into the second liquid tank 14 via 1. Since the discharge port 19 opens toward the membrane element 13 when the undiluted solution (reaction solution) is pumped into the second liquid tank 14,
It flows out toward the membrane element 13 discharged from the discharge port 19. Therefore, the undiluted solution (reaction solution) pressure-fed from the first liquid tank 12 to the second liquid tank 14 flows from the lower side to the upper side in the flow passage formed between the membrane elements 13.

At the bottom of the second liquid tank 14, the air outlet 2
Air is flowing out from 5, and by the rise of this bubble,
In the flow path between the membrane elements 13, a water flow from the lower side to the upper side is generated. Therefore, in the flow path between the membrane elements 13, the water flow generated by the rise of the bubbles and the discharge port 19
Together with the discharge flow of the undiluted solution (reaction solution) discharged from the membrane, the film surface velocity is significantly increased. Therefore, the permeation rate through the membrane of each membrane element 13 is significantly increased, and efficient membrane separation is performed. The permeated water that has permeated the membrane of each membrane element 13 is sucked by the suction pump 26 and discharged through the water collection pipe 27.

The circulation pump 18 continues to operate and the first liquid tank 1
The stock solution in 2 is pumped into the second liquid tank 14, and the amount of permeated water discharged by the suction pump 26 is smaller than the discharge amount of the circulation pump 18. Therefore, the excess stock solution in the second liquid tank 14 is passed through the overflow pipe 17 to the first liquid tank 1
Overflow into 2. That is, in this embodiment, the aeration process is performed in the first liquid tank 12, the raw solution is pressure-fed to the second liquid tank 14 to perform membrane separation in the membrane element 13, and the stock solution remaining in the membrane separation is fed to the first liquid tank 12. It will be returned and aerated again.
Therefore, the rate of membrane separation of untreated components is lowered, and the stability of treatment is high.

Ascending bubbles come into contact with the membrane surface of the membrane element 13, and an interface between air and the undiluted solution is generated on the membrane surface. When this interface rises, a large shearing force is generated on the membrane surface. Therefore, by this shearing force, the adhering substances such as the cake layer formed on the film surface can be peeled off, and the film surface is purified. Therefore, the membrane separation is efficiently performed for a long time.

However, when the membrane separation is carried out for a long time, the gel-like deposit grows on the membrane surface or a cake layer is formed, so that the membrane separation efficiency is lowered. If this happens, it is necessary to clean and clean the membrane surface.

In the present embodiment, the capacity of the first liquid tank 12 is set to be large and the capacity of the second liquid tank 14 is set to be small, and the second liquid tank 14 is set.
The volumes of both liquid tanks are set so that the stock solution therein can be stored in the first liquid tank 12. That is, the surplus water amount of the first liquid tank 12 is set to be larger than the water amount of the second liquid tank 14. Therefore, when the undiluted solution in the second liquid tank 14 is transferred into the first liquid tank 12 by using a pump or the like, the membrane surface can be directly washed without pulling out the membrane element 13 in the second liquid tank 14. . Then, when this cleaning work is completed, the stock solution can be easily returned to the second liquid tank 14 by operating the circulation pump 18.

Further, in this embodiment, the second liquid tank 14 is located at a position higher than the first liquid tank 12, specifically, the discharge port 19 opened in the second liquid tank 14 is higher than the first liquid tank 12. The second liquid tank 14 is installed at such a height that it can be positioned. Therefore, a bypass flow path 28 that bypasses the circulation pump 18 is provided, a water stop valve 29 is provided in the middle of the bypass flow path 28, and the water stop valve 29 is closed in the state of membrane separation. Then, when cleaning the membrane surface, the operation of the circulation pump 18 is stopped and the water stop valve 29 is opened. When the water shutoff valve 29 of the bypass flow passage 28 is opened in this way, the stock solution in the second liquid tank 14 flows backward in the stock solution delivery pipe 21 due to the difference in water level, and the bypass flow path 2
It flows down into the first liquid tank 12 via 8. Therefore, the stock solution in the second liquid tank 14 can be easily transferred into the first liquid tank 12 without using a separate pump or the like. Then, when the work of cleaning the membrane surface is completed, by closing the water shutoff valve 29 of the bypass flow passage 28 and then operating the circulation pump 18, the stock solution can be easily returned to the second liquid tank 14.

In the above-described embodiment, the case where the aeration process is performed in the first liquid tank 12 has been described, but the first liquid tank 12 may be a precipitation tank. That is, the aeration may be stopped, or the aeration pipe 15 itself may not be provided in the first liquid tank 12 and used as a precipitation tank. Of course, a coagulating sedimentation tank may be used.

Further, in the above-mentioned embodiment, the first liquid tank 12 and the second liquid tank 14 are provided separately, but the present invention is not limited to this, and the space is divided by the partition wall so that they are adjacent to each other. May be. For example, in another embodiment shown in FIG.
A partition wall 30 partitions the space between the liquid tank 12 and the second liquid tank 14, and an overflow passage 31 is formed in an upper portion of the partition wall 30 (a position higher than the highest liquid level of the first liquid tank 12).
The bottom portion of the second liquid tank 14 is set higher than the bottom portion of the first liquid tank 12, and the first liquid tank 12 has a surplus capacity set to be larger than the capacity of the second liquid tank 14. Then, the suction side of the circulation pump 18 is connected to the first liquid tank 12 side, and the discharge port 19 of the discharge side pipe 23 is opened upward below the membrane element 13 in the second liquid tank 14.

Therefore, the reaction liquid aerated in the first liquid tank 12 can be discharged from the discharge port 19 toward the flow path between the membrane elements 13 by the operation of the circulation pump 18, and the flow velocity on the membrane surface is dispersed. This can be increased in combination with the bubbles in the trachea 24, and efficient membrane separation can be performed. The surplus liquid in the second liquid tank 14 is returned from the overflow channel 31 into the first liquid tank 12 and then again. Can be aerated.

When the membrane surface of the membrane element 13 is to be cleaned, the reaction solution in the second liquid tank 14 is transferred into the first liquid tank 12 and directly washed in the tank 14 without pulling out the membrane element 13. can do. When a flow path switching valve is provided in the flow path of the circulation pump 18, the reaction liquid in the second liquid tank 14 can be easily transferred by the operation of the circulation pump 18 when transferring it into the first liquid tank 12. .

Then, as in this embodiment, the first liquid tank 12
If the second liquid tank 14 and the second liquid tank 14 are integrally provided, the installation space can be effectively utilized, and if the circulation pump 18 and the like are installed in the space formed below the second liquid tank 14, the space efficiency is further enhanced.

[0027]

As described above, according to the present invention, the treated stock solution in the first liquid tank is pumped into the second liquid tank by the operation of the circulation pump, and the stock solution is pumped into the second liquid tank. At this time, since the ejection port is arranged below the membrane element, the ejection port vigorously flows out toward the membrane element ejected from the ejection port. Therefore, the undiluted treatment liquid pressure-fed from the first liquid tank to the second liquid tank flows in the flow path between the membrane elements, and the membrane surface velocity is significantly increased. Therefore, the permeation rate through the membrane of each membrane element is remarkably increased, and the undiluted solution contacting the membrane surface is the treated undiluted solution pumped from the first liquid tank, and efficient membrane separation is performed. Then, the surplus stock solution in the second liquid tank overflows into the first liquid tank through the overflow channel and is processed again. Therefore, the rate of membrane separation of untreated components is lowered, and the stability of treatment is high. Further, when the surplus water amount of the first liquid tank is made larger than the water amount of the second liquid tank, the liquid of the second liquid tank is stored in the first liquid tank and the membrane of the membrane element in the second liquid tank is stored. It is possible to directly clean the surface, and it is possible to easily carry out the cleaning work of the film surface, which has required a lot of trouble and time in the past, in a short time.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an embodiment of an immersion type membrane separation device in which a first liquid tank and a second liquid tank are provided separately.

FIG. 2 is a cross-sectional view of an embodiment of an immersion type membrane separation device in which a first liquid tank and a second liquid tank are partitioned by a partition wall and integrally provided.

FIG. 3 is a schematic piping diagram of a flow path switching valve and the like in which liquid can be reversibly transferred between the first and second liquid tanks by a circulation pump.

FIG. 4 is a cross-sectional view of a conventional immersion type membrane separation device.

FIG. 5 is a cross-sectional view of a conventional immersion-type membrane separation device in which a reaction tank and an immersion tank are separately provided.

[Explanation of symbols]

 11 Immersion Type Membrane Separator 12 First Liquid Tank 13 Membrane Element 14 Second Liquid Tank 15 Aeration Pipe 16 Overflow Outlet of Second Liquid Tank 17 Overflow Pipe 18 Circulation Pump 19 Discharge Port 21 Raw Liquid Delivery Pipe 23 Pipe 24 Diffuser Pipe 26 Suction Pump 30 Partition wall 32 Flow path switching valve

Claims (1)

[Claims] 1. A first liquid tank for storing an undiluted solution and a second liquid tank in which a membrane element is immersed are provided, and a first undiluted solution of the second liquid tank is provided between the first and second liquid tanks. An immersion type membrane separation characterized in that an overflow passage is provided for overflowing the liquid tank, and a discharge side pipe of a circulation pump whose suction side is connected to the first liquid tank is arranged below the membrane element of the second liquid tank. apparatus.