JPH1057780A - Dipped membrane separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restore the permeation flux of a membrane by surely removing the contaminant of the membrane generated in a permeated water collection operation even if the cross-sectional area of the permeated water conduit of the membrane constituting a membrane module is small and the number of the membranes is too large. SOLUTION: A membrane module 11 is dipped in the water in a treating tank 10, and the permeated water is collected by the negative pressure generated in the permeated water conduit of the membrane constituting the module 11 by this dipped membrane separator. A liq. chemical injection means 20 for injecting a cleaning liq. chemical in a liq. chemical tank 21 into the one end of the permeated water conduit of the membrane of the module 11 with a liq. chemical injection pump P2 and a circulating means 23 for sucking the cleaning liq. chemical injected by the means 20 from the other end of the permeated water conduit of the membrane with a suction pump P3 and circulating it to the liq. chemical tank 21 are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a large number of hollow fiber membranes such as reverse osmosis membranes, ultrafiltration membranes, microfiltration membranes, polymer membranes, alumina ceramic membranes, tubular tubular membranes,
Immerse the membrane module composed of flat membrane in the water of the processing tank,
An immersion type membrane separation device that installs and collects the permeated liquid that has passed through the membrane due to the head difference and the negative pressure generated by the suction pump inside the permeation channel of the membrane that constitutes the membrane module. The present invention relates to an immersion-type membrane separation device that effectively cleans a membrane that has been washed with a cleaning chemical solution and restores its permeability.

[0002]

2. Description of the Related Art In such an immersion type membrane separation apparatus, cakes and gels adhered to the membrane surface when the permeated water permeates through the membrane due to intermittent stoppage of sampling of permeated water, bubbling, upward flow of an air lift, and the like. The layer is peeled off to maintain the permeation flux of the membrane, but during long-term operation, membrane contamination due to contaminants such as cakes and gel layers occurs, and the contamination gradually progresses,
Maintaining the permeation flux becomes difficult.

[0003]

For this reason, according to Japanese Patent Application Laid-Open No. Hei 7-116482, the present applicant introduces a cleaning liquid into a permeation channel of a membrane constituting a membrane module and replaces it with permeate in the permeation channel. It has been proposed to remove contaminants adhered to the outer surface of the membrane by back washing in which the washing liquid permeates the membrane in the opposite direction to the permeated water. Although the permeation flux is recovered by this, the permeated water of all the permeated water channels is replaced with the washing liquid when the permeated water channels of the membranes constituting the membrane module are narrow, such as a hollow fiber membrane, and there are many permeated water channels. Since backwashing is impossible, a part of the membrane is subjected to the next water sampling step until the recovery by washing is not sufficient, so that the water sampling efficiency is reduced.

[0004]

Therefore, according to the present invention, a cleaning chemical solution is forcibly flown from one end to a permeate channel of a membrane constituting a membrane module by a pump, and the cleaning chemical solution injected into the permeate channel is supplied from the other end. By forcibly sucking and circulating with a pump, all contamination of the membrane of the membrane module can be washed with a small amount of the washing solution.

[0005]

Accordingly, the present invention relates to an immersion type membrane separation apparatus for immersing a membrane module in water of a treatment tank and collecting a permeate which has passed through the membrane. A chemical liquid injection means for injecting a cleaning liquid in a chemical liquid tank at one end with a liquid injection pump, and a cleaning liquid injected by the chemical liquid injecting means from the other end of the permeate channel of the membrane with a chemical liquid suction pump, and into the liquid tank. And circulating means for circulating.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the illustrated embodiment, reference numeral 10 denotes a treatment tank to which raw water is supplied, 11 denotes a membrane module immersed and installed in the water of the treatment tank, and the membrane constituting the membrane module has, for example, a very large cross-sectional area. A plurality of hollow fiber membranes 12 each having a small hollow permeation channel, and the plurality of hollow fiber membranes are disposed between two vertically collecting water pipes 13 and 14 each having a closed lower end. Each end of the permeate channel of the hollow fiber membrane destined for each one communicates with the inside of the water collecting pipes 13 and 14, respectively. Then, the upper end portion of the water collecting pipe 13 is water sampling pipe 15 from the suction pump P ₁ of permeate are connected.

In the processing tank 10, an air diffuser 16 to which air is supplied from a blower B is laid below the membrane module 11. When the blower B supplies air to the diffuser 16, the air diffuser 16 Ejects fine air bubbles into the processing tank, and the air bubbles float on the water surface while being in contact with a large number of hollow fiber membranes 12 constituting the membrane module. An upward flow occurs, and the raw water convects in the tank as shown by the arrow in the drawing.

[0008] operating the suction pump P ₁ of permeate in this state, the raw water in the tank, due to the depth of each hollow fiber membrane 12 permeated water permeable within the outside, from the water surface where the membrane modules are immersed The water flows into the permeation channel due to the negative pressure effect in the permeation channel caused by the head difference and the suction of the suction pump P ₁ , and is collected into a storage tank (not shown) via the water sampling pipe 15 and the suction pump P ₁ . The fine bubbles generated by the air diffuser 16 prevent contaminants from adhering to the outer surface of the hollow fiber membrane when floating in contact with each hollow fiber membrane. As described above, even if the permeated water sampling operation is continuously performed for a long period of time while preventing the contaminants from adhering to the hollow fiber membrane due to bubbles, membrane contamination due to the contaminants occurs as described above. It gradually progresses, and it becomes difficult to maintain the permeation flux, and the permeation water sampling efficiency decreases.

According to the present invention, even if the cross-sectional area is small as in the case of the permeate channel of the hollow fiber membrane, and even if there are many such channels, the entire permeate channel is washed with a chemical solution and the permeate flux of the entire membrane is restored. a than was to recover in the figure, 21 is chemical bath containing wash liquor, 22 liquid injection for injecting a wash liquor in the chemical bath on one end of the transmission waterways membrane module by liquid injection pump P ₂ Pipe, chemical solution tank 21, chemical solution injection pump P
_{2. The} chemical injection tube 22 constitutes the chemical injection means 20.
Further, 24 is connected to the other end of the transmission waterways membrane module, the liquid medicine extraction tube to dispense the injected the transmission in waterways chemical chemical solution suction pump P _3, 25 to the discharge port of the chemical suction pump P ₃ A chemical circulation pipe for connecting and returning the chemical solution sucked by the pump P ₃ to the chemical solution tank 21. The chemical solution discharge pipe 24, the chemical solution suction pump P ₃ , and the circulation pipe 25 constitute a chemical solution circulation means 23.

In this embodiment, the chemical liquid injection pipe 22 of the chemical liquid injection means 20 is connected to the water sampling pipe 15 from the water collecting pipe 13, and the water collecting pipe 13 sucks permeated water more than the connection position with the chemical liquid injection pipe. An on-off valve V ₁ is provided on the pump P ₁ side, and an on-off valve V ₂ is provided on the chemical liquid injection pipe 22. Therefore, at the time of water sampling operation of permeate previously described keep-off valve V ₁ open, the on-off valve V ₂ closed. Further, the liquid medicine extraction tube 24 Yes connected to the lower end of the other water collecting pipe 14, the note decane-off valve V ₃ in front of the chemical suction pump P ₃ provided in the 24, water sampling permeate Keep closed during operation.

In order to perform the washing, the on-off valve V _{1 of the} water sampling pipe 15 is used.
Is closed, and the on-off valve V _{2 of} the chemical liquid injection pipe 22 and the chemical liquid discharge pipe 2
4 of the opening and closing valve V ₃ together in the open, liquid injection pump P _2, to operate the pump P ₃ out same note. Thus the cleaning chemical liquid in the chemical tank 21 is liquid injection pipe 22 by the pump P _2, is injected from the top through the Tomizukan 15 within the water collecting pipe 13, the water collecting pipe 1
3, many permeate channels, permeate remaining in the collection pipe 14,
And injected wash liquor is dispensing tube 24 from the lower end of the water collecting pipe 14, is sucked by the suction pump P _3, it is supplied to the chemical liquid tank 21 by the circulation pipe 25, circulates.

[0012] Since the cleaning chemical liquid supplied to the upper end of the water collecting tube 13 is sucked through the lower end from the dispensing tube 24 of the other water collecting pipe 14 with a chemical solution suction pump P _3, wash liquor many of the cross-sectional It flows evenly in the permeate channel having a small area, penetrates all the hollow fiber membranes, and removes contamination of the membrane.

[0013] Incidentally, the chemical liquid suction pump P ₃ of the suction pressure, or flow rate suction, injection pressure of the liquid injection pump P _2, or smaller than the flow rate west, to pass through the membrane raw water permeation in waterways in the treatment tank When the chemical solution flows through the permeation channel, the chemical solution permeates the membrane from inside to outside, and actively removes and separates contaminants stuck from the outside of the membrane and contaminants attached to the outside of the membrane. To be able to.

[0014] Thus, when the washing step with wash liquor predetermined time, bottom is removed from the film of the processing tank, so peel contaminants are deposited, opening valve V ₄ of the sludge drawn tube 17 provided in the bottom of the tank , Together with part of the raw water in the treatment tank, is discharged out of the pipe 17.

When the washing process is completed, the valves V ₂ , V ₃ , V ₄ are closed, V ₁ is opened, and the permeated water suction pump P ₁ is operated to start the water sampling operation. 14, transmission waterways entire hollow fiber membrane, the water collecting pipe 13, downstream of the opening and closing valve V ₁ of the Tomizukan 15, the wash liquor suction pump P ₁ remaining downstream of the on-off valve V ₂ of the liquid injection tube to the suction Because it discharges,
The discharged cleaning chemical liquid is supplied to, for example, a chemical liquid tank, and is supplied to a storage tank when permeated water is to be discharged.

In this embodiment, a hollow fiber membrane has been described as an example of a membrane having a permeate channel with a small cross-sectional area. However, the present invention is not limited to a hollow fiber membrane, and the present invention can be applied to other membranes, By doing so, it is possible to remove all the contamination of the membrane constituting the membrane module and to recover the permeation flux.

[0017]

As is clear from the above, according to the present invention, when the membrane is contaminated by performing the permeated water sampling operation by the membrane module, one end of the permeated water passage of the membrane is filled with the cleaning chemical in the chemical tank. The chemical liquid injection pump is forcibly injected, and the cleaning liquid injected from the other end of the permeation water channel is sucked by the chemical liquid suction pump, so that even if the cross-sectional area of the permeation water channel is small, However, contamination of the membrane can be reliably removed, and the permeation flux of the membrane can be reliably restored. Since the cleaning solution sucked by the solution suction pump is returned to the solution tank and is circulated and used, the consumption of the solution can be reduced, which is economical.

If the suction pressure of the chemical liquid suction pump is smaller than the injection pressure of the chemical liquid injection pump, during the cleaning process,
Raw water in the treatment tank permeates through the membrane and is not sucked into the permeate channel. Conversely, cleaning chemicals flowing through the permeate channel permeate the membrane from inside to outside, and contaminants and stabs from the outside of the membrane. It can positively remove and peel off contaminants adhering to the outside, improving the cleaning effect.

[Brief description of the drawings]

FIG. 1 is a flow sheet of one embodiment of an immersion type membrane separation device of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Treatment tank to which raw water is supplied 11 Membrane module 12 Hollow fiber membrane which constitutes a membrane module 13 Hollow fiber membrane water collecting pipe 14 Hollow fiber membrane water collecting pipe 15 Permeated water sampling pipe 16 Aeration pipe 20 Chemical liquid injection means 21 Chemical liquid injection Chemical liquid tank of means 22 Chemical liquid injection pipe of chemical liquid injection means 23 Chemical liquid circulation means 24 Chemical liquid outflow pipe of chemical liquid circulation means 25 Chemical liquid circulation pipe of chemical liquid circulation means P ₁ Permeated water suction pump P ₂ Chemical liquid injection pump P ₃ Chemical liquid suction pump

Claims (1)

[Claims] 1. A membrane module is immersed in water of a treatment tank,
In a submerged membrane separation device for sampling a permeated liquid that has passed through a membrane, a chemical liquid injection means for injecting a cleaning liquid in a chemical tank with a chemical liquid injection pump at one end of a permeated water channel of the membrane of the membrane module,
A immersion type membrane separation device, comprising: a circulating means for sucking the cleaning chemical liquid injected by the chemical liquid injection means from the other end of the membrane permeation channel with a chemical liquid suction pump and circulating the same to the chemical liquid tank.