JP2000126563A - Method and device for sensing membrane breakage for hollow fiber membrane filter and filtration method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a membrane breakage sensing method for a hollow membrane filter for sensing the membrane breakage of respective modules inexpensively and with good accuracy during the filtration process and also provide a device thereof. SOLUTION: In a membrane breakage sensing method, raw water in a raw water chamber 12 is filtered through a hollow fiber membrane 18 and introduced into a treatment chamber 14 wherein the raw water is treated, and treated water is discharged from the water treatment chamber 14 to the outside of a housing 10 through a purified water discharged pipe 26, and air reservoir 44 is formed in the treated water discharge pipe 26 and the fluctuation of the water level of the air reservoir 44 is sensed to detect the breakage of the hollow fiber membrane 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting membrane breakage in a hollow fiber membrane filtration device and a device therefor.

[0002]

2. Description of the Related Art Conventionally, as a method for detecting membrane breakage in a hollow fiber membrane filtration device, there is one disclosed in Japanese Patent Application Laid-Open No. 8-173774. The membrane rupture detection method disclosed in this publication, when air is introduced into raw water to pressurize the raw water chamber,
If the hollow fiber membrane is broken, pressurized air in the raw water leaks into the treated water chamber through the hollow fiber membrane. This is to detect breakage.

[0003]

However, in this detection method, not only is the bubble detecting device expensive, but also a pump and the like are required, and the device becomes complicated. For this reason, in this conventional detection method, a particle monitor is provided for a unit as a whole, instead of detecting each of the membrane modules individually. Therefore, in this method, it is impossible to detect which module in the unit has the film breakage.

The present invention has been made in view of such circumstances, and a membrane breakage in a hollow fiber membrane filtration device capable of detecting a membrane breakage of each module accurately and inexpensively and detecting it during a filtration process. An object of the present invention is to provide a detection method and an apparatus therefor.

[0005]

In order to achieve the above object, the present invention provides a method for detecting a film breakage according to claim 1 of the present invention.
Membrane break detection in a hollow fiber membrane filtration device that filters raw water in a raw water chamber through a hollow fiber membrane, guides it to a treated water chamber, and discharges treated water from the treated water chamber to outside the housing through a treated water discharge pipe. The method is characterized in that an air reservoir is formed in the treated water discharge pipe, and the breakage of the hollow fiber membrane is detected by detecting a change in the water level of the air reservoir.

According to the film rupture detecting device of the second aspect of the present invention,
In a hollow fiber membrane filtration device for filtering raw water in a raw water chamber through a hollow fiber membrane, guiding the raw water to a treated water chamber, and discharging treated water from the treated water chamber to outside the housing through a treated water discharge pipe, An air reservoir is formed in the water discharge pipe, and a water level gauge is provided in the air reservoir. Further, in the hollow fiber membrane filtration method according to the third aspect, in a work process including a filtration process, a back pressure cleaning process, an air scrubbing process, a drainage process, and a water injection process, the process may be performed between the air scrubbing process and the drainage process. A film rupture detecting step according to the film rupture detecting method according to claim 1 or 2 is provided.

[0007] In the above invention, when the hollow fiber membrane breaks, air is stored in the air pool, thereby lowering the water level of the air pool. If the water level is detected by an inexpensive and simple measuring instrument such as a water level meter, it is possible to detect air leakage, that is, breakage of the hollow fiber membrane. According to the present invention, an expensive measuring device such as a bubble monitor is not required, and therefore, a film breakage detecting device can be provided for each module, and the film breakage can be detected for each module.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a method for detecting membrane breakage in a hollow fiber membrane filtration device according to the present invention and the device will be described in detail below with reference to the accompanying drawings. FIG.
1 is a structural diagram of a hollow fiber membrane filtration device according to the present invention. The illustrated hollow fiber membrane filtration device has a plurality of housings 10, and the housing 10 is defined by a partition 10a into a raw water chamber 12 and a treated water chamber 14, and the partition 10a has a hollow fiber membrane support member 16 Are arranged. The hollow fiber membrane support member 16 has a hollow fiber membrane 18 suspended therefrom,
The open end 18 a of the hollow fiber membrane 18 is located facing the treated water chamber 14. Therefore, these chambers 12 and 14 are connected to each other via the hollow fiber membrane 18.

One end of a raw water supply pipe 20 is connected to a lower portion of the raw water chamber 12 of each housing 10, and the other end of the raw water supply pipe 20 is connected to a raw water supply main pipe 22. A raw water supply valve 24 is interposed in the raw water supply main pipe 22, and the raw water is supplied to the raw water chamber 12 by opening the raw water supply valve 24. On the other hand, each housing 10
One end of a treated water discharge pipe 26 is connected to the ceiling of the treated water chamber 14, and the other end of the treated water discharge pipe 26 is connected to a treated water discharge main pipe 28. A treated water discharge valve 30 is interposed in the treated water discharge main pipe 28,
By opening the treated water discharge valve 30, the treated water in the treated water chamber 14 is discharged to the outside.

Further, one end of a cleaning air supply pipe 32 is connected to a lower portion of the raw water chamber 12 of each housing 10, and the other end of the cleaning air supply pipe 32 is connected to a cleaning air supply main pipe 34. It is connected. A cleaning air supply valve 36 is interposed in the cleaning air supply main pipe 34, and cleaning air is supplied to the raw water chamber 12 by opening the cleaning air supply valve 36. Also, each housing 1
The upper ends of the raw water chambers 12 are connected to one ends of overflow pipes 38, respectively.
Is connected to the overflow main pipe 40.
An overflow valve 42 is interposed in the overflow main pipe 40, and the raw water in the raw water chamber 12 is discharged by opening the overflow valve 42.

The treated water discharge pipe 26 is partially bent at a substantially right angle to form a vertical portion 26a and a horizontal portion 26b, and an air reservoir 44 is formed on an extension of the vertical portion 26a. An air vent valve 4 is provided at the upper end of the air reservoir 44.
6 are provided. Further, a water level gauge (water level gauge) 48 is provided in the air reservoir 44. In the hollow fiber membrane filtration device thus configured, raw water is supplied from the raw water supply main pipe 22 to the raw water chamber 12 via the raw water supply pipe 20. This raw water is filtered by the hollow fiber membrane 18, and the treated water is guided to the treated water chamber 14 from the hollow fiber membrane open end 18a. At this time (at the start of operation), the air reservoir 44 is filled with treated water by opening the air vent valve 46. Therefore, at the time of normal operation in which the film is not broken, the air pool 44
Has no air.

To detect the breakage of the membrane, the overflow valve 42 is closed to close the overflow main pipe 40, and the cleaning air supply valve 36 is opened to supply pressurized air through the cleaning air supply pipe 32. It is supplied to the raw water chamber 12. At this time, when the hollow fiber membrane 18 is not broken, air does not pass through the membrane 18, so that no air leaks and the air reservoir 44 remains full. Here, if the hollow fiber membrane 18 is broken, air leaks from the broken portion 18b of the membrane 18 to the treated water chamber 14. Then, the leaked air accumulates in an air reservoir 44 provided in the treated water discharge pipe 26. Therefore, the air pushes down the treated water in the air pool 44. Then, the change in the water level is detected by a water level gauge or a liquid level gauge 48 provided in the air reservoir 44, whereby the breakage of the hollow fiber membrane 18 is confirmed.

Thus, the water level gauge or the liquid level gauge 48
As a result, when a change (decrease) in the water level in the air pool 44 is confirmed, the operation of the hollow fiber membrane filtration device is stopped, for example,
The hollow fiber membrane 18 of the corresponding housing 10 is replaced with another one. The raw water supply pipe 2 of each housing 10
0, the treated water discharge pipe 26, the cleaning air supply pipe 32, and the overflow pipe 38 may be provided with a shut-off valve to stop the function of only the housing 10 in which the hollow fiber membrane 18 is broken. In that case, the function of only the corresponding housing 10 is stopped, so that the hollow fiber membrane 18 of the housing 10 can be replaced with another one.

In this hollow fiber membrane filtration device, since the air reservoir 44 is provided for each housing 10, breakage of the membrane can be detected for each module. In the above embodiment, the air reservoir 44 is connected to the vertical portion 2 of the treated water discharge pipe 26.
Although it is formed on the extension of 6a, the installation position is not limited to the extension of the vertical portion 26a of the treated water discharge pipe 26, and may be formed, for example, in the middle of the horizontal portion 26b.

Further, by providing a window in the air reservoir 44, a change in the water level, that is, the presence or absence of breakage of the film can be visually detected. FIG. 2 shows the flow of all the steps during the normal operation without the film breakage detection step. In the filtration step, the raw water supply water valve 24 is opened, and the raw water is supplied from the raw water supply pipe 20 to the raw water chamber 12.
To supply. During this operation, the overflow valve 42 and the cleaning air supply valve 36 are closed, the treated water discharge valve 30 is opened, and the inside of the housing 10 is pressurized to obtain treated water. After filtration for a certain period of time, that is, in the back pressure washing step, the raw water supply valve 24 is closed, the overflow valve 42 is opened, and the treated water flows back through the treated water discharge pipe 26. Next, the air scrubbing process is started, the cleaning air supply valve 36 is opened, and the cleaning air is supplied from the cleaning air supply pipe 32 to rub the hollow fiber membranes 18 together. The turbidity adhering to the surface of the film 18 is removed. After that, in the drainage step, the raw water supply valve 24 is opened, and the concentrated water in which the turbid matter floating from the surface of the hollow fiber membrane 18 in the housing 10 floats is drained. At this time, the overflow valve 42 may be opened to drain the water under natural flow. Alternatively, the overflow valve 42 may be closed to supply air from the cleaning air supply pipe 32 to pressurize the inside of the housing 10 to forcibly drain the water. is there. Thereafter, in the water injection step, the raw water is injected into the housing 10 from the raw water supply pipe 20, and after the water is full, the flow returns to the filtration step again.

FIG. 3 is a flow chart showing all the steps of the operation of the hollow fiber membrane filtration device according to the present invention. In this flow chart, a film break detection step for detecting a film break after the air scrubbing step during normal operation shown in FIG. 2 is provided. In the film rupture detection step, after the air scrubbing step, only the overflow valve 42 is closed, and the cleaning air supply pipe 32 supplies cleaning air as it is. As a result, an air layer is generated in the upper portion of the housing 10, and the air layer is pressurized by the cleaning air. Since the rupture of the membrane occurs 5 to 20 mm below the hollow fiber membrane support member 16, even if raw water (concentrated water) remains inside the housing 10, the rupture portion 18 b of the membrane is in the air layer and pressurized from there. Air leaks into treated water.

Further, as shown in FIG. 4, there may be a case where a membrane rupture detecting step is provided after the draining step. In this case, the raw water is injected into the housing 10 from the raw water supply pipe 20 after closing the overflow valve 42 at the time of the water injection step.
As a result, the inside of the housing 10 is pressurized, and if the film is broken, air leaks from the broken portion or 18b.

[0018]

According to the present invention, the breakage of the film can be detected by a simple device, so that the detection for each module can be performed accurately at low cost. In addition, break detection can be performed during the operation process.

[Brief description of the drawings]

FIG. 1 is a perspective view conceptually showing a hollow fiber membrane filtration device for performing a membrane breakage detection method according to the present invention.

FIG. 2 is a flowchart showing a normal operation method.

FIG. 3 is a flowchart showing an operation method according to the present invention.

FIG. 4 is a flowchart showing another operation method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Housing 10a ... Partition wall 12 ... Raw water chamber 14 ... Treatment water chamber 16 ... Hollow fiber membrane support member 18 ... Hollow fiber membrane 18a ... Open end 18b ... Breaking part 20 ... Raw water supply pipe 22 ... Raw water supply main pipe 24 ... Raw water supply Valve 26: treated water discharge pipe 26a: vertical part 26b ... horizontal part 28 ... treated water discharge main pipe 30 ... treated water discharge valve 32 ... cleaning air supply pipe 34 ... cleaning air supply main pipe 36 ... cleaning air supply valve 38 ... overflow pipe 40 ... overflow main pipe 42 ... overflow valve 44 ... air reservoir 46 ... air vent valve 48 ... water level gauge (liquid level gauge)

Continued on the front page (72) Inventor Teruhiro Kitazawa 1-1-1 Uchikanda, Chiyoda-ku, Tokyo F-term in Hitachi Plant Construction Co., Ltd. 4D006 GA02 HA03 HA19 JA18A JA70A KA11 KC02 KC03 KC13 KC14 KE24Q LA03

Claims (3)

[Claims] 1. A hollow fiber membrane filter for filtering raw water in a raw water chamber through a hollow fiber membrane, guiding the raw water to a treated water chamber, and discharging treated water from the treated water chamber to the outside of the housing through a treated water discharge pipe. A method of detecting membrane breakage in an apparatus, comprising forming an air pocket in the treated water discharge pipe and detecting a break in the hollow fiber membrane by detecting a change in the water level of the air pool. A method for detecting membrane breakage in a membrane filtration device. 2. A hollow fiber membrane filter for filtering raw water in a raw water chamber through a hollow fiber membrane, guiding the raw water to a treated water chamber, and discharging treated water from the treated water chamber to the outside of the housing via a treated water discharge pipe. In the apparatus, an air reservoir is formed in the treated water discharge pipe, and a water level gauge is provided in the air reservoir. 3. The membrane breakage according to claim 1, wherein in a working step including a filtration step, a back pressure washing step, an air scrubbing step, a drain step, and a water injection step, between the air scrubbing step and the drain step. A hollow fiber membrane filtration method comprising a membrane breakage detection step by a detection method.