JP3341428B2 - Operating method of immersion membrane device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated body in which a plurality of flat membranes are laminated, a laminated body in which a plurality of hollow fiber membranes are formed in a planar or interdigital shape, and a plurality of tubular membranes. The present invention relates to a method for operating an immersion membrane apparatus using a parallel connection as a membrane unit.

[0002]

2. Description of the Related Art An immersion membrane apparatus in which the above-mentioned membrane unit is immersed in a liquid in a treatment tank, and the inside of the membrane unit is suctioned to obtain filtered water permeated through the membrane is conventionally known. It is also known to provide an air diffuser below the membrane to remove the filter cake.

[0003]

When this immersion membrane device is operated to perform membrane filtration, non-filtration substances such as a concentration polarization layer, a gel layer and a cake layer adhere to the membrane surface. As the thickness of the non-filtration material increases, the filtration resistance increases, the filtration pressure increases, and the filtration efficiency decreases significantly. For this reason, if an air diffuser is provided below the membrane unit and the membrane filtration operation is performed for a certain time,
Or, when the filtration pressure reaches a certain level during the membrane filtration operation, the operation is stopped and backwashing is performed.However, before and after this backwashing, the air diffuser is operated, and the entire lower surface of the membrane unit is exposed to air bubbles from below, and the membrane is washed. It is necessary to peel off the non-filtration substance adhering to the membrane surface due to the upward bubbles and the shear force of the upward water flow. In this case, it is necessary to maintain a convection space in which the liquid in the tank flows downward and circulates around the membrane unit, and the filling rate of the membrane in the processing tank is reduced by the convection space.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a method for disposing a plurality of membrane units in a liquid in a processing tank, separated by a partition plate in the liquid, in the liquid in the tank, and below the individual membrane units. In the immersion membrane device which obtains the filtration treatment water permeated through the membrane, the membrane diffusion operation is stopped, and the air diffusion device is alternately operated before and after performing the backwash. According to a second aspect of the present invention, the air diffuser is operated alternately during the membrane filtration operation.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In each of the illustrated embodiments, reference numeral 10 denotes a processing tank.
The membrane unit 11 is immersed in the liquid in the processing tank, and the suction pipe 13 connected to the pump 12 sucks the inside of the membrane unit, and the undiluted solution in the processing tank that has passed through the membrane unit 11 is filtered. Collect water as water. The membrane unit is formed by stacking a plurality of flat membranes or hollow fiber membranes as described above,
Alternatively, a plurality of laminated bodies of interleaved membrane elements,
Alternatively, a plurality of tubular membranes are connected in parallel.

In the embodiment shown in FIG. 1, two membrane units 11A and 11B are placed in a processing tank 10 by a partition plate 14 whose upper end is below the liquid level.
Are disposed adjacent to each other, and each of the membrane units 11A,
Air diffusers 15A and 15B are individually provided below 11B. A diffuser 15A, 15B is a common blower 16
To the opening and closing valves 18A, 18 provided on the pipes.
B can be operated individually. The membrane filtration operation is stopped, and the opening / closing valves 18A and 18B are alternately opened and closed before and after the backwash. For example, the air bubbles are exposed to the membrane unit 11A for 15 minutes from the air diffuser 15A, and the air diffuser 15 is used for the next 15 minutes.
From B, air bubbles are poured into the membrane unit 11B, and this is repeated. As a result, bubbles rising from the air diffuser 15A cause an upward flow between the membranes of the membrane unit 11A, and the non-filtration substances attached to the membrane surface of the membrane unit 11A due to the bubbles and the upward water flow are separated from the membrane surface. At the same time, a downward flow is generated between the membranes of the membrane unit 11B, and the non-filtration substance attached to the membrane surface is separated by the downward flow. When the air diffuser 15B is operating, the non-filtration substance adhered to the membrane surface of the membrane unit 11B is peeled off from the membrane surface by bubbles and upward water flow, and adheres to the membrane surface of the membrane unit 11A. The non-filtered material is separated from the membrane surface by the downward water flow generated between the membranes. The air diffusion may be performed after the operation of the membrane is stopped, or may be performed during the operation of the membrane.

In the embodiment shown in FIG. 2, four membrane units 11A, 11B, 11C and 11D are arranged in a processing tank 10 so as to be separated from each other by three partition plates 14A, 14B and 14C. Below the unit are individually air diffusers 15A,
15B, 15C and 15D are provided. The four air diffusers are connected to a common blower 16 by a branch pipe 17, and the four air diffusers can be individually operated by four on-off valves 18A, 18B, 18C, 18D provided in the branch pipe. While the membrane filtration operation is being performed, or the operation is stopped, the on-off valve is operated before and after the backwash, and for example, the air diffusers 15A, 15B, 1
Operate for 15 minutes in the order of 5C, 15D, or 1
5A and 15C, 15B and 15D are alternately operated for 15 minutes. An upward flow due to air bubbles is generated between the membranes of the membrane units above the operating air diffuser, and the air bubbles and the upward water flow separate the non-filtration substance adhering to the membrane surface, and the air diffuser is not operated. A downward flow is generated between the membranes of the membrane units above the membrane unit, and this downward water flow separates the non-filtration substance adhering to the membrane surface from the membrane surface.

[0008]

As is apparent from the above, by alternately operating the air diffusers, an upward flow of air bubbles is generated between the membranes of the membrane units above the operating air diffusers, and the air bubbles and the air bubbles are generated. The non-filtration substance adhering to the membrane surface is removed by the upward water flow. Then, a downward flow is generated between the membranes of the membrane units above the air diffuser whose operation has been stopped, and this downward water flow separates the non-filtration substance adhering to the membrane surface. Therefore, there is no need to maintain a convection space for generating the downward flow between the membrane units,
The film filling rate in the processing tank increases. Further, when filling the same number of membrane units, the size of the processing tank used is greatly reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment of an immersion film apparatus according to the present invention.

FIG. 2 is a sectional view of another embodiment of the immersion film apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Processing tank 11A Membrane unit 11B Membrane unit 11C Membrane unit 11D Membrane unit 12 Pump 13 Suction tube 14 Divider 14A Divider 14B Divider 14C Divider 15A Air diffuser 15B Air diffuser 15C Air diffuser 15D Air diffuser 16 17 Branch pipe 18A On-off valve 18B On-off valve 18C On-off valve 18D On-off valve

Claims (2)

(57) [Claims] 1. A plurality of membrane units are arranged in a liquid in a processing tank, separated by a partition plate in the liquid, and an air diffuser is individually provided below each of the membrane units to provide filtration through the membrane. A method for operating a submerged membrane apparatus for obtaining treated water, wherein the membrane filtration operation is stopped and the air diffuser is alternately operated before and after performing backwashing. 2. A plurality of membrane units are arranged in a liquid in a processing tank, separated by a partition plate in the liquid, and an air diffuser is individually provided below each of the membrane units to perform filtration through the membrane. A method for operating a submerged membrane apparatus for obtaining treated water, wherein the air diffuser is operated alternately during a membrane filtration operation.