JPH07116482A - Submerged type membrane separation device - Google Patents

Abstract

PURPOSE:To perform effective washing by a method wherein washing liquid is introduced into a permeation chamber of a membrane unit, without imparting excessive pressure to a membrane, to replace permeation water, in the chamber, having permeated the membrane with the washing liquid, and the washing liquid is made to permeate the membrane in a direction opposite to the direction of the flow of the water so that gel-like cake attached to the outer surface of the membrane is separated and removed. CONSTITUTION:In a submerged type membrane separation device wherein a membrane unit 10 provided with membranes and a permeation chamber 11, into which water having permeated the membranes flow in, is submerged in a liquid to perform a membrane separation process, a plurality of connection ports 23 in communication with the permeation chamber 11 are formed in the unit 10, and a takeout pipe 2 including a suction pump P1 is connected to one of the ports 23 and a feed pipe 5 for water or chemical liquid is connected to other one of the ports 23 so that the water or chemical is introduced through the feed pipe 5 into the permeation chamber by operating the suction pump to replace the liquid in the chamber with the water or chemical liquid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a reverse osmosis membrane, an ultrafiltration membrane, a microfiltration membrane, a membrane such as a polymer membrane, an inorganic (alumina ceramic etc.) membrane, and a water permeation membrane that permeates the membrane. The present invention relates to an immersion type membrane separation device that performs a membrane separation treatment by immersing a membrane unit having a chamber in a liquid.

[0002]

2. Description of the Related Art Immersion type membrane separators are capable of obtaining permeated water by utilizing a water head difference based on the water depth in an immersion tank in which a membrane unit is immersed and performing a membrane separation with a low energy by a suction pump. The applicant of the present patent proposed in Japanese Patent Application No. Hei 5-15941, a patent application dated September 28, 1993, a membrane unit consisting of a number of flat membranes, and permeated when the liquid in the tank was extracted by washing the dipping tank. The membrane was effectively prevented from being damaged by the weight or water pressure of the permeated water remaining in the chamber. By the membrane unit,
When the permeation process of the permeated water is carried out, the cake of gel-like substance adheres to the outer surface of the membrane, and the permeation of the cake is gradually obstructed. is necessary.

[0003]

The most effective method for removing the cake is backwashing in which the chemical solution is injected into the permeation chamber by pressurized water or the like, and the chemical solution is permeated through the membrane in the opposite direction to the permeation water. Pressure acts on the membrane causing frequent breakage of the membrane.
For this reason, there is no choice but to adopt a method of adding a chemical to the liquid in the dipping tank and washing the liquid. However, this method requires a large amount of chemical liquid and increases the burden of waste liquid treatment. Further, it is necessary to make the dipping tank chemically resistant.

[0004]

The present invention was developed in view of the above, and a plurality of connection ports communicating with a permeation chamber are provided in a membrane unit immersed in a liquid, and one of the connection ports is a suction pump. The permeated water extraction pipe is connected, and the water or chemical liquid supply pipe is connected to the other one of the connection ports, and water or the chemical liquid is introduced into the permeation chamber through the supply pipe by operating the suction pump. It is characterized in that it can be replaced with.

[0005]

Examples FIGS. 4 to 7 show a membrane unit 10 made of a flat membrane proposed by the applicant in the patent application dated September 28, 1993, and a flat membrane element 11 for one sheet constituting the membrane unit is shown.
Is a flat, square, net-shaped flow path spacer 12 made of tricot knitted fabric, and flat membranes 13, 13 of the same size are superposed on both surfaces, and the four peripheral edges are sealed 14 by heat, adhesion, high-frequency welding, or the like. To form an integral body and form a permeation chamber 11 ′ surrounded by a seal 14 between the two flat membranes 13, 13. still,
The flat sheet membrane element may be formed by directly forming a film on both the front and back surfaces of the spacer of the porous member. Each flat sheet membrane element is provided with water passages 15 and 15 at diagonal corners in the permeation chamber 11 ′ surrounded by the seal 14. Reference numeral 16 denotes an elastic gasket which is arranged at a corner having a water passage port 15 of the flat sheet membrane element and maintains a predetermined water passage interval 18 between two adjacent flat sheet membrane elements, and which is a right angle corresponding to the corner of the flat sheet membrane element. Triangular or quadrangular with two sides, water passage 1
5 has an opening 17 of the same size communicating with 5.

Reference numerals 19 and 20 denote end plates for sandwiching and opposing a row of a plurality of flat sheet membrane elements arranged side by side with a gasket 16 at a water-passing interval and having the same size as the membrane element. Each end plate has a water inlet 15, 15 for the flat sheet membrane element.
A through hole 21 communicating with is opened in the same diagonal direction. The through holes of the end plates 19 and 20 are such that the portions facing each other are the water passage port 15 of the flat sheet membrane element and the opening 17 of the gasket 16.
And a large-diameter portion 22 of the same size as the above, and the remaining portion is a small-diameter portion 24 through which the tightening bolt 25 passes. Further, a connection port 23 opened to the outer surface is provided at the back of the large diameter portion 22.

In order to assemble the membrane unit, a predetermined number of membrane elements 11 are lined up in a row through the gasket 16 (the water inlet 15 of the flat membrane element and the opening 17 of the gasket communicate with each other) and all communicate with each other. The bolts 25 pass through the water inlet 15 of the flat membrane element and the openings 17 of all the gaskets in series, and the through holes 2 are formed at the respective ends of the bolts 25.
1 is fitted and the flat plate element 11 and the gasket 16 are sandwiched between the end plates 19 and 20, and the nut 26 screwed into each end of the bolt is tightened to the end plates 19 and 20, and the flat film element and the gasket are sandwiched. Make one. It should be noted that at each end of the bolt 25, a portion located in the small diameter portion 23 of the through hole is
The ring 27 is fitted and sealed. As a result, the large-diameter portion 22 of the through hole of the end plate, the opening 17 of the gasket, and the water passage hole 15 of the membrane element are connected in series, and the water passages 28 and 29 for connecting the permeation chambers 11 'of the individual flat sheet membrane elements are connected. Occurs in two diagonal directions.

FIG. 1 shows that the above membrane unit is immersed in the liquid of the dipping tank 1 so that one of the water channels is on the top and the other is on the bottom plate, and the end plates 19 and 20 of the water channel 28 are on the upper side. The permeate extraction pipe 2 having a suction pump P in the middle is connected to one of the connection ports 23, and the other connection port is closed with a plug. The take-out pipe branches into two downstream of the suction pump, and one of the branch pipes 2a rises, and the water surface is the same as that of the immersion tank 1 or opens to the permeate storage tank 3 above it from above, The other 2b extends straight and opens into the drainage tank 4. Branch pipe 2a, the 2b provided in the middle of the on-off valve V _1, V _2. One of the connection ports 23 in the end plates 19 and 20 of the water channel 29 below the membrane unit projects into the liquid in the storage tank 3 from above, connects the replacement water supply pipe 5, and connects the other connection port. 23 is closed with a stopper. And
A chemical injection pipe 7 for injecting the chemical liquid in the chemical liquid tank 6 with a pump P ₂ is connected in the middle of the supply pipe 5. The supply pipe 5 is provided with an opening / closing valve V ₃ on the water channel 29 side of the connection point of the chemical injection pipe, and the immersion tank 1
Is provided with a raw water supply pipe and a mud discharge pipe 8 at the bottom.

To collect permeated water, open the on-off valve V ₁ ,
₂ and V ₃ are closed and the suction pump P ₁ is operated. As a result, of the liquid in the immersion tank, the permeated water that has permeated the membrane due to the suction of the pump and the water head difference flows from the permeation chamber to the pipes 2 and 2a and enters the storage tank 3.

The permeated water sampling step is performed, and when a certain amount of cake adheres to the outer surface of the membrane, the on-off valve V ₁ is closed and V ₂ and V ₃ are closed.
Is opened, and the suction pump P ₁ and the chemical solution pump P ₂ are operated for cleaning. As a result, the permeated water that fills the permeation chamber of the membrane unit is drawn by the suction pump, flows through the pipes 2 and 2b and enters the drainage tank 4, and at the same time, the permeated water in the storage tank 3 has a head difference from the immersion tank 1, And flowing by suction of the suction pump toward the membrane unit in the replacement water supply pipe 5 to merge with the chemical liquid injected in the chemical injection pipe 7 to become a cleaning liquid having a predetermined concentration and to apply excessive pressure to the membrane. Instead, enter the permeation chamber. In this way, when the cleaning liquid replaces the permeated water in the permeation chamber, the suction pump P ₁
Then, the operation of the chemical liquid pump P ₂ is stopped, V ₂ is closed in addition to the on-off valve V ₁ , and the cleaning liquid is sent to the permeation chamber by the water head difference between the storage tank 3 and the immersion tank 1, and the cleaning liquid in the permeation chamber is transferred to the inner surface of the membrane. To the outer surface and peel off the cake adhering to the outer surface. Since the cleaning liquid permeates the membrane in the direction opposite to the permeated water, the cake easily peels off from the outer surface of the membrane and is removed. The removed cake is discharged from the dipping tank by opening the valve of the mud discharge pipe 8.

When the cleaning is completed, the on-off valve V ₁ is closed and V ₂ , V
₃ is opened, the suction pump P ₁ is operated, the cleaning liquid in the permeate chamber is sucked into the drainage tank 4, and at the same time, the permeated water in the storage tank is sucked by the suction pump and the supply pipe is supplied by the head difference between the storage tank and the immersion tank. 5
To the permeate chamber, and the permeate replaces the cleaning liquid in the permeate chamber. After the permeate chamber is replaced with the permeate, the on-off valve V ₁ is opened, V ₂ and V ₃ are closed, and the permeate water sampling process is restarted.

In this embodiment, the chemical liquid in the chemical liquid tank 6 is used as a cleaning liquid having a predetermined concentration, and the permeated water in the storage tank 3 is used to replace the cleaning liquid in the permeation chamber. However, as in the embodiment of FIG. Separately, a fresh water tank 9 may be provided above the dipping tank, and the replacement water supply pipe 5 may be rushed into the fresh water of the fresh water tank from above to dilute or replace the chemical liquid with the fresh water. Further, as in the embodiment of FIG. 3, two outlet pipes 2 and 2'having suction pumps are connected to the water channel 28, one of the outlet pipes 2 is opened to the storage tank 3 from above, and the other outlet pipe 2 '. causes the opening from above the drainage tank 4, water sampling step of permeate operated suction pump P ₁ of the take-out tube 2, when replacing the transmission chamber of the liquid to drive the suction pump P ₃ of the take-out tube 2 ' You may do it.

The membrane of the membrane unit is not limited to the illustrated flat membrane, and may be a hollow fiber membrane, a tubular membrane or any other membrane. Further, the connection position of the permeated water extraction pipe to the membrane unit and the connection position of the replacement water supply pipe are opposed to each other in the illustrated embodiment, which can prevent a short circuit of water or a chemical solution, but are not necessarily opposed to each other. Need not be provided. Further, the chemical liquid in the chemical liquid tank 6 is pump P
_{2. It} was supplied to the supply pipe 5 by the chemical injection pipe 7 and was combined with the permeated water from the storage tank 3 and the fresh water from the fresh water tank 9 to be supplied to the permeation chamber. However, as shown in FIG. The injection pipe 7 may be directly connected to the connection port of the membrane unit to be directly supplied to the permeation chamber, and may be mixed with permeated water or fresh water supplied from the supply pipe 5 in the permeation chamber to be diluted with the cleaning liquid. Further, the chemical liquid may be supplied by a drop with a chemical injection pipe having a valve, instead of being supplied by the pump P ₂ .

[0014]

As is apparent from the above, according to the present invention, the permeated water in the permeation chamber is replaced with the cleaning liquid without applying excessive pressure to the membrane during cleaning, and the cleaning liquid is changed from the inner surface to the outer surface of the membrane. To penetrate. As a result, the cleaning liquid that permeates the film in the reverse direction is peeled off from the gel cake attached to the outer surface of the film, so that a very excellent cleaning effect can be obtained in combination with the chemical action of the cleaning liquid.

[Brief description of drawings]

FIG. 1 is a flow sheet of a first embodiment of the present invention.

FIG. 2 is a flow sheet of a second embodiment of the present invention.

FIG. 3 is a flow sheet of a third embodiment of the present invention.

FIG. 4 is a perspective view of an example of a flat membrane unit.

FIG. 5 is a perspective view in which a part of a flat sheet membrane element that constitutes a membrane unit is peeled off.

FIG. 6 is a front view of a gasket overlaid on a membrane element.

FIG. 7 is an enlarged cross-sectional view of a part of an assembled state of the flat sheet membrane unit.

[Explanation of symbols]

1 Immersion tank 2 Extraction pipe 3 Storage tank 4 Drainage tank 5 Supply pipe 6 Chemical liquid tank 7 Chemical injection pipe 8 Mud pipe 9 Fresh water tank 10 Membrane unit 11 'Permeation chamber 13 Membrane 23 Connection port P ₁ Suction pump

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kunihiro Iwasaki 3-4-7 Nishishinjuku, Shinjuku-ku, Tokyo Kurita Industry Co., Ltd.

Claims (1)

[Claims] 1. A submerged membrane separation apparatus for immersing a membrane unit, which comprises a membrane and a permeation chamber into which water permeated through the membrane, in a liquid to perform membrane separation treatment, wherein the membrane unit communicates with the permeation chamber. Operation of the suction pump by providing a plurality of connection ports, connecting the permeate extraction pipe with a suction pump to one of the connection ports, and connecting the water or chemical supply pipe to the other one of the connection ports. The immersion type membrane separation device is characterized in that water or a chemical solution is introduced into the permeation chamber through the supply pipe to replace the liquid in the chamber.