JP4379352B2 - Operation method of membrane treatment apparatus - Google Patents

Description

  The present invention relates to an operation method of a membrane treatment apparatus such as a hollow fiber membrane separation apparatus provided with a membrane for filtering water to be treated, and more particularly to an operation method of a membrane treatment apparatus configured to detect membrane breakage. In the present invention, the breaking of the film means the breaking or breaking of the film, and the breaking includes a minute breaking such as a pinhole.

  In a membrane treatment device such as a hollow fiber membrane separation device, a filtration step of passing water to be treated (raw water) to one side separated by a membrane and taking out the treated water from the other side; The operation is continued by alternately performing a washing step of washing with water.

  When the membrane breaks, the raw water is mixed into the filtered water and the quality of the filtered water is deteriorated. Therefore, the membrane breakage needs to be detected at an early stage.

  As a technique for detecting film breakage in a film processing apparatus, a technique has been proposed in which air is supplied to one side of a film and bubbles that leak from the breakage point to the other side of the film are detected to detect film breakage. .

For example, in JP-A-2003-144866, the inside of a housing is partitioned into a raw water chamber and a treated water chamber by a hollow fiber membrane, the outer wall side of the hollow fiber membrane is a raw water chamber, and the inner wall side of the hollow fiber membrane is a treated water chamber. In the external pressure type hollow fiber membrane filtration device, a transparent tube provided with a photoelectric sensor is provided at the upper part of the raw water chamber, and when the membrane breakage is detected, the raw water chamber is filled with the raw water, and the treated water chamber A method is disclosed in which air below the bubble point of the hollow fiber membrane is injected from the side and the breakage of the hollow fiber membrane is confirmed visually or by detecting bubbles with the photoelectric sensor.
JP 2003-144866 A

  In the method of Japanese Patent Application Laid-Open No. 2003-144866, when a minute break such as a pinhole occurs in the hollow fiber membrane, a very small amount of air bubbles leak into the raw water chamber, and the air bubbles are caused by the surface tension of the hollow fiber membrane. Since it adheres to the outer peripheral surface or accumulates in the dead end portion in the raw water chamber, the bubbles do not reach the photoelectric sensor, and the membrane breakage cannot be detected accurately.

  An object of the present invention is to solve the above-mentioned problems and to provide a method for operating a film processing apparatus capable of reliably detecting even a minute film rupture.

  Another object of the present invention is to provide a method for operating a film processing apparatus that can determine the degree of film breakage.

  The operation method of a membrane treatment apparatus of the present invention (Claim 1) is an operation method of a membrane treatment apparatus provided with a membrane for filtering the treatment liquid, and the treatment liquid is supplied to one side separated by the membrane. A filtration operation step of removing the treatment liquid from the other side, and a membrane breakage detection that detects a membrane breakage by supplying pressurized gas to the one side and detecting the gas flowing out to the other side by the detection means In the operation method of the film processing apparatus for performing the process, when the gas is detected by the detecting means when the liquid is supplied to the one side after the film breakage detecting step, the film is broken slightly. It is characterized by determining that it exists.

  The operation method of the film processing apparatus according to claim 2 is that in claim 1, when gas is detected by the detection means in the film rupture detection step, it is determined that the film is broken, and when it is not detected, after the film rupture detection step, The liquid is supplied to the one side, and the microfracture is determined based on whether or not gas is detected.

  The operation method of the film processing apparatus according to claim 3 is the method according to claim 1 or 2, wherein a cleaning step of supplying a gas-liquid mixture to the one side and cleaning the membrane is performed prior to the membrane breakage detection step. At this time, when gas is detected by the detection means, it is determined that a large-scale film rupture has occurred, and when gas is not detected at this time, a film rupture detection step of supplying the pressurized gas is performed. It is what.

  According to a fourth aspect of the present invention, there is provided a method for operating the membrane treatment apparatus according to any one of the first to third aspects, wherein the membrane treatment apparatus is an internal pressure type hollow fiber membrane separation apparatus.

  According to a fifth aspect of the present invention, there is provided a method for operating the membrane treatment apparatus according to any one of the first to third aspects, wherein the membrane treatment apparatus is an external pressure type hollow fiber membrane separation apparatus.

  The operation method of the membrane treatment apparatus according to claim 6 is the method according to any one of claims 1 to 5, wherein when the membrane breakage is detected, the electrical resistance of the liquid on the other side separated by the membrane is measured, Gas is detected based on this change in electrical resistance.

  The operation method of the membrane treatment apparatus according to claim 7 is the operation method of claim 6, wherein a pair of electrodes are arranged so as to be in contact with the liquid on the other side separated by the membrane, and a voltage is applied between the electrodes. The occurrence of film breakage is detected from the pattern of change in voltage, current or conductivity between the electrodes.

  According to an eighth aspect of the present invention, there is provided a method for operating the membrane treatment apparatus according to the seventh aspect, wherein a gas or gas-liquid mixture is passed through the membrane treatment apparatus in which the membrane is broken to detect the change pattern of the voltage, current, or conductivity. The change pattern is stored in the storage means, and the gas, gas or liquid mixture is circulated through the membrane processing apparatus whose membrane breakage has not been confirmed, and the voltage, current, or conductivity pattern is detected, and this pattern is stored in the storage device. The presence or absence of a film rupture is determined in comparison with the change pattern stored in the means.

  The operation method of the membrane processing apparatus of the present invention (Claim 1) is to supply a pressurized gas to one side separated by a membrane and detect the gas flowing out to the other side by a detecting means to break the membrane. When the liquid is supplied to the one side after the film rupture detection step to be detected, it is determined that the film is micro-ruptured when gas is detected by the detection means.

  When the film break is fine, the gas flowing out to the other side separated by the film in the film break detection process is extremely small, so this gas adheres as a bubble to the other side of the film and is detected. There is no movement to the means. However, in the present invention, after this membrane breaking step, a liquid is supplied to one side of the membrane and is allowed to flow out from the other side surface of the membrane, and the other side is discharged by the liquid flowing out from the other side surface of the membrane. The bubbles adhering to the side surface are pulled apart, and the bubbles are moved to the detection means together with the flow of the effluent, and detected by the detection means. Can be determined.

  In the operation method of the film processing apparatus according to the second aspect, when the gas is detected by the detecting means in the film rupture detection step, it is immediately detected that the film rupture is larger than the micro rupture. When no film rupture is detected in the film rupture detection step, after the film rupture detection step, a liquid is supplied to the one side, and the presence or absence of micro rupture is confirmed based on whether or not gas is detected.

  In the operation method of the film processing apparatus according to claim 3, the gas-liquid mixture is supplied to one side across the film prior to the film breakage detecting step, and at this time, the gas is detected by the detecting means. Sometimes it is determined that a large-scale film break has occurred, and the subsequent film break detection step can be omitted. If it is determined that a large-scale film judgment has not occurred, a film break detection step is performed to confirm the presence or absence of micro-breaks.

  This method of operating the membrane treatment device can be suitably applied when the membrane treatment device is an internal pressure type hollow fiber membrane separation device (Claim 4) or an external pressure type hollow fiber membrane separation device (Claim 5).

  In the operation method of the film processing apparatus according to the sixth aspect, when the film is ruptured, bubbles are mixed into the liquid on the other side through the rupture portion in the film rupture detection step. Then, the electric resistance of the liquid changes as the bubbles pass through the electric resistance detection unit. Therefore, film breakage can be detected from this change in electrical resistance.

  According to a seventh aspect of the present invention, a pair of electrodes is disposed on the other side of the membrane, and when the membrane breaks, bubbles are configured to flow between the electrodes. When bubbles flow in between the electrodes, the electrical resistance between the electrodes changes as compared with the case where only the liquid flows between the electrodes. Therefore, the occurrence of film breakage can be detected based on this change in electrical resistance.

  Since the change in the electrical resistance of the liquid can be detected with a simple device, the equipment cost is low.

  In order to detect the change in the resistance of the liquid, a constant voltage may be applied between the pair of electrodes, and the current value between the electrodes may be detected.

  Alternatively, a constant current may be passed between the electrodes, and a change in voltage between the electrodes may be detected. Further, a change in conductivity between the electrodes may be detected, and the change in conductivity may be used as an index value for a change in the electrical resistance of the liquid.

  In order to determine the breakage of the film from the change in the current value, voltage value or conductivity, as described in claim 8, the gas or gas-liquid mixture is circulated through the film processing apparatus having the broken film, and the voltage and current Alternatively, a change pattern of conductivity is detected, the change pattern is stored in a storage means, and a gas or gas / liquid mixture is passed through a film processing apparatus in which film breakage has not been confirmed. It is easy to detect this and compare this pattern with the change pattern stored in the storage means.

Hereinafter, the present invention will be described in detail with reference to the drawings.
<First Embodiment>
FIG. 1 is a schematic diagram of a membrane treatment apparatus to which an operation method according to an embodiment of the present invention is applied, and FIG. 2 is a block diagram of the membrane breakage detection apparatus of FIG. In FIG. 1, four hollow fiber membranes are used for the sake of clarity, but in reality, a large number of hollow fiber membranes are arranged.
[Configuration of membrane processing equipment]
A plurality of hollow fiber membranes 4 are bundled and arranged in the casing 2 of the internal pressure type hollow fiber membrane module 1. The lower and upper ends of the bundle of hollow fiber membranes 4 are bound by sealing materials 6 and 8 made of synthetic resin or the like, respectively. The sealing materials 6 and 8 are, for example, in a disk shape, and the outer peripheral surface or outer peripheral edge thereof is in watertight contact with the inner surface of the casing 2. A raw water chamber 10 is formed on the lower side of the lower sealing material 6, a circulating water chamber 14 is formed on the upper side of the upper sealing material 8, and the treated water chamber 12 is formed between both the sealing materials 6 and 8. Is formed.

  The upper end side of the hollow fiber membrane 4 penetrates the sealing material 8, and the opening 4 a at the upper end faces the circulating water chamber 14. Similarly, the lower end side of the hollow fiber membrane 4 penetrates the sealing material 6, and the opening 4 b at the lower end faces the raw water chamber 10.

On the side of the raw water chamber 10 of the casing 2, a raw water inlet nozzle 10a and a gas inlet nozzle 10b are provided. Raw water inlet nozzle 10a is raw water pipe 21, via the raw water valve V ₁ and the raw water pump P are connected to the raw water tank 20. From the point between the raw water nozzle 10a and the raw water valve V ₁ of the raw water pipe 21, discharge pipe 24 is branched with a drain valve V _2. Gas inlet nozzle 10b is connected to a compressor C via a gas pipe 27 having a valve V _3.

A circulating water outlet nozzle 14 a is provided on the circulating water chamber 14 side of the casing 2. The circulation water outlet nozzle 14a is connected to the raw water tank 20 through a circulating water pipe 31 having a circulating water valve V _4. From the point between the circulation water outlet nozzle 14a of the circulating water pipe 31 and the circulating water valve V _4, a vent pipe 33 provided with a vent valve V ₅ is branched.

A treated water outlet nozzle 12 a is provided on the treated water chamber 12 side of the casing 2. The treated water outlet nozzle 12a is connected to the film breakage detection device 50 through the treated water pipe 41, the film breaking detection apparatus 50, the treatment water tank 40 through the treated water pipe 42 having a valve V ₆ It is connected.

In the treated water chamber 12, a region between the upper end of the treated water outlet nozzle 12a and the lower surface of the sealing material 8 is a dead end portion 12A.
[Configuration of membrane breakage detector]
As shown in FIG. 2, the film breakage detecting device 50 includes a measuring unit 51 composed of a pair of electrodes 51a and 51b, a power source 52 that applies a voltage to the measuring unit 51, and the current, voltage, or conductivity of the measuring unit 51. It comprises a measuring unit 53 for measuring, a storage unit 55 for storing changes with time of current, voltage or conductivity, and a determination unit 56 for determining the generation of bubbles from a pattern of changes with time of current, voltage or conductivity.

  The electrodes 51 a and 51 b are in contact with the treated water discharged from the treated water chamber 12. The material of the electrodes 51a and 51b is preferably platinum or stainless steel so as not to be affected by the pH of the treated water.

  Next, the operation content when the film breakage detection apparatus 50 is a constant voltage method will be described. The power source 52 applies a constant voltage between the electrodes 51a and 51b of the measurement unit 51. With this applied voltage, a current corresponding to the electrical resistance of the treated water flows between the electrodes 51a and 51b. When bubbles exist in the treated water passing through the measurement unit 51, the current between the electrodes 51a and 51b changes when the bubbles pass between the electrodes 51a and 51b.

  The measuring unit 53 measures the current value between the electrodes 51a and 51b.

  Next, the current value change pattern stored in the storage unit 55 and the current value change pattern of the current value measured by the measurement unit 53 are compared with each other by the determiner 56 to determine the presence or absence of film breakage.

  When the film breakage detection device 50 is of a constant current method, the power source 52 applies a voltage so that a constant current flows between the electrodes 51 a and 51 b of the measurement unit 51. When bubbles exist in the treated water passing through the measurement unit 51, the voltage between the electrodes 51a and 51b changes when the bubbles pass between the electrodes 51a and 51b. The measuring unit 53 measures the voltage value between the electrodes 51a and 51b. Next, the change pattern of the voltage value stored in the storage unit 55 and the temporal change pattern of the voltage value measured by the measurement unit 53 are compared with each other by the determiner 56 to determine the presence or absence of film rupture.

  When the film breakage detection device 50 is of the conductivity detection method, the power source 52 applies a predetermined voltage between the electrodes 51a and 51b of the measurement unit 51, and supplies a current between the electrodes 51a and 51b. When bubbles exist in the treated water passing through the measurement unit 51, the conductivity between the electrodes 51a and 51b changes when the bubbles pass between the electrodes 51a and 51b. This change is measured by the measurement unit 53, and then the conductivity change pattern stored in the storage unit 55 is compared with the measured conductivity change pattern with time by the determiner 56 to determine the presence or absence of film breakage. Is done.

The flow of water or gas in the filtration process and the cleaning process of the membrane processing apparatus configured as described above is as follows.
[Filtering process]
In the filtration step, the valves V ₁ , V ₄ , V ₆ are opened (however, V ₄ is closed in the case of total filtration), the other valves V ₂ , V ₃ , V ₅ are closed, and the raw water pump P Actuate. Raw water raw water tank 20 is the raw water pipe 21, the raw water pump P, through the valve _{V 1,} and flows from the raw water inlet nozzle 10a to the raw water chamber 10. The raw water in the raw water chamber 10 flows into the hollow fiber membrane 4 from the opening 4b at the lower end of the hollow fiber membrane 4, and a part of this raw water passes through the hollow fiber membrane 4 and flows into the treated water chamber 12, The remainder flows into the circulating water chamber 14 from the opening 4 a at the upper end of the hollow fiber membrane 4.

  The treated water in the treated water chamber 12 flows out from the treated water outlet nozzle 12 a and is sent to the treated water tank 40 through the treated water pipe 41, the membrane breakage detection device 50 and the pipe 42.

Circulating water in the circulation water chamber 14 flows out from the circulation water outlet nozzle 14a, the circulating water pipe 31, is water in the raw water tank 20 via a valve V _4.
[Membrane cleaning process with air / water mixture]
When the membrane treatment apparatus is washed with the air / water mixture water, the valve V ₄ is closed, the valves V ₃ and V ₅ are opened, and the compressor C is operated in the state of the filtration step. Thereby, the pressurized gas from the compressor C passes through the inside of the hollow fiber membrane 4 together with the raw water supplied by the raw water pump P, and the hollow fiber membrane 4 is washed.

The mixture of the gas and raw water that has passed through the inside of the hollow fiber membrane 4 flows into the circulating water chamber 14 and is discharged out of the system through the drain pipe 33.
[Detection of film breakage during film cleaning process (method of claim 3)]
In this embodiment, the large-scale membrane breakage of the membrane module is detected during the membrane cleaning step. In order to perform this detection, the film breakage detection device 50 measures the voltage change accompanying the current change between the electrodes 51a and 51b. If there is no film rupture, the voltage is normally constant, so that the determination unit 56 determines that there is no large-scale film rupture.

  When the change pattern is detected, for example, if the change in the pulse pattern obtained by binarizing the voltage change does not exceed the threshold, it is determined that there is no large-scale film breakage, and the threshold is exceeded (for example, the pulse If the pattern frequency is equal to or higher than a predetermined value, or if the pulse voltage is zero (gas detection) continues for a predetermined period or longer, it is determined that there is a large-scale film breakage. Note that the detection of bubbles in this membrane washing step is considered to be due to the occurrence of membrane breakage of a considerably large scale (for example, a plurality of hollow fiber membranes are cut).

  In this embodiment, when it is determined that there is a large-scale membrane rupture, the fine membrane rupture detection step described later is omitted, and the membrane treatment apparatus is immediately stopped to replace or repair the internal pressure type hollow fiber membrane module 1.

  In this description, a change is measured by passing a current between the electrodes 51a and 51b with a constant voltage power supply. However, a change in the applied voltage accompanying the passage of a bubble is caused when a constant current is passed between the electrodes 51a and 51b with a constant current power supply. The film breakage may be determined from the change pattern.

Alternatively, the electrical conductivity between the electrodes 51a and 51b may be measured, and film breakage may be determined based on the change pattern of the electrical conductivity.
[Detection Step of Film Breakdown by Gas Supply (Method of Claim 2)]
After one or more cycles of the filtration process and the washing process, the pump P is stopped, the valves V ₁ , V ₂ , V ₄ are closed, V ₃ , V ₅ , V ₆ are opened, and the compressor C is opened. Operate and supply only pressurized gas to the hollow fiber membrane 4. The gas pressure is, for example, about 100 to 300 kPa, particularly preferably about 150 to 250 kPa.

  In the same manner as in [Detection of film breakage during the film cleaning step], the film breakage detection device 50 measures the voltage change accompanying the current change between the electrodes 51a and 51b. If there is no film rupture, the voltage is normally constant, so that the determination unit 56 determines that there is no medium-scale or larger film rupture.

  When the change pattern is detected, for example, if the change in the pulse pattern obtained by binarizing the voltage change does not exceed the threshold, it is determined that there is no medium-scale film breakage, and the threshold is exceeded (for example, the pulse When the frequency of the pattern is equal to or higher than a predetermined value, or when the pulse voltage is zero (gas detection) continuously for a predetermined period or longer), it is determined that there is a medium-scale film breakage. Note that the film breakage detected by the gas supply is of a level that was not detected in the film cleaning step, and thus is determined to be a medium scale.

In this embodiment, when it is determined that there is a medium-scale membrane breakage, the membrane treatment apparatus is immediately stopped and the internal pressure type hollow fiber membrane module 1 is replaced or repaired.
[Step of Determining Fine Fracture of Film (Method of Claim 1)]
When the membrane breakage is fine, the amount of gas flowing out from the outer surface of the hollow fiber membrane 4 through the breakage portion is extremely small, so this gas adheres as bubbles to the outer surface of the membrane, and the bubbles break the membrane. It does not move to the detection device 50 (note that the state in the module at this time will be described in detail later with reference to FIG. 4). Therefore, the attached bubbles are separated from the film or the like and guided to the detection device 50 as follows to determine the presence or absence of fine film breakage.

That is, after the medium-scale membrane breakage detection process by the gas supply, the compressor C is stopped, the valves V ₂ , V ₃ , V ₅ are closed, the other valves V ₁ , V ₄ , V ₆ are opened, and the raw water The pump P is activated. The raw water in the raw water tank 20 flows into the raw water chamber 10, and further flows into the hollow fiber membrane 4 from the opening 4 b at the lower end of the hollow fiber membrane 4.

  Part of the raw water flowing into the hollow fiber membrane 4 permeates the membrane wall of the hollow fiber membrane 4 and flows out from the outer surface of the hollow fiber membrane 4 into the treated water chamber 12.

  At this time, when bubbles are attached to the outer surface of the hollow fiber membrane 4, the treated water flowing out from the outer surface of the hollow fiber membrane 4 pulls the bubbles away from the outer surface of the hollow fiber membrane. The separated bubbles move on the flow of treated water and move to the film breakage detection device 50, and are detected by the film breakage detection device 50.

  The method for determining film breakage by the film breakage detection device 50 is the same as described above. In this case, the membrane breakage is determined to be fine because it is a small amount of bubble leakage that is detected when the raw water flow is resumed.

In this embodiment, when it is determined that there is a fine membrane breakage, the membrane treatment apparatus is immediately stopped, and the internal pressure type hollow fiber membrane module 1 is replaced or repaired. However, when the quality of the treated water is within the allowable range, the process may return to the filtration operation process as it is, and the filtration operation may be performed as it is until the periodical inspection.
{Description of the state in the internal pressure type hollow fiber membrane module 1 when fine membrane breakage occurs}
The state in the internal pressure type hollow fiber membrane module 1 when a fine membrane breakage such as a pinhole has occurred will be described in detail with reference to FIG. FIG. 4 (a) is a partial cross-sectional view for explaining the state in the internal pressure hollow fiber membrane module 1 of FIG. 1 at the end of the medium-scale membrane breakage detection step, and FIG. 4 (b) is a fine breakage of the membrane. It is a fragmentary sectional view explaining the state in the film | membrane processing apparatus of FIG. 1 in the process of determining.

  As shown in FIG. 4 (a), in the medium-scale membrane breakage detection step by gas supply, a part of the pressurized gas supplied to the inside of the hollow fiber membrane 4 is outside the hollow fiber membrane 4 from the fine fracture portion 4a. To leak. A part of the leaked gas rises in the treated water chamber 12 and accumulates in the dead end part 12A, and the remaining part adheres to the outer surface of the hollow fiber membrane 4 by surface tension as fine bubbles.

  For this reason, bubbles leaked from the hollow fiber membrane 4 hardly reach the membrane breakage detection device 50.

  Next, as shown in FIG. 4 (b), raw water is supplied into the hollow fiber membrane 4 in the step of judging the microfracture of the membrane. At this time, a part of the raw water permeates the membrane wall of the hollow fiber membrane 4 and flows out from the outer surface of the hollow fiber membrane 4 into the treated water chamber 12. Then, the bubbles adhering to the outer surface of the hollow fiber membrane 4 are pulled away from the outer surface by the treated water flowing out from the outer surface of the hollow fiber membrane 4.

  A part of the separated bubbles moves on the flow of the treated water flowing out from the outer surface and moves to the film breakage detecting device 50, and is detected by the film breakage detecting device 50.

The remaining part of the bubble that has been pulled off accumulates in the dead end portion 12A, and eventually the dead end portion 12A is filled with gas and further overflows from the dead end portion 12A. The overflowing gas rides on the flow of treated water and moves to the film breakage detection device 50, and is detected by the film breakage detection device 50.
{Description of the state in the internal pressure type hollow fiber membrane module 1 when a medium-scale or larger membrane break occurs}
A state in the internal pressure type hollow fiber membrane module 1 when a medium-scale or larger membrane breakage such as one or more hollow fiber membranes 4 is broken will be described with reference to FIG. FIG. 5 (a) is a partial sectional view for explaining the state in the membrane treatment apparatus of FIG. 1 in the initial stage of the medium-scale film breakage detection process, and FIG. 5 (b) is the final stage of the medium-scale film breakage detection process. It is a fragmentary sectional view explaining the state in the film | membrane processing apparatus of FIG.

As shown in FIG. 5 (a), when the rupture portion 4b is generated in the hollow fiber membrane 4 by cutting, a relatively large amount of bubbles leaks from the rupture portion 4b due to the supply of gas or water in the membrane rupture detection step. To do. Since the leakage of the bubbles is relatively large, as shown in FIG. 5B, the gas fills the dead end portion 12A, overflows from the dead end portion 12A, and moves along the upper end of the treated water outlet nozzle 12a. Then, it is detected by the film breakage detection device 50.
{Method of accurately detecting film breakage by the film breakage detecting device 50 (the method of claim 10)}
In order to detect a film break more accurately, the following operation method may be performed.
(1) Storage of output pattern of detection device by known device for membrane rupture Prior to detection of membrane rupture, each membrane module in which minute membrane rupture has been confirmed is incorporated as shown in FIG. Then, after the membrane module is filled with water, a membrane rupture detection step and a step of determining a micro rupture of the membrane are performed.

  In the step of determining the minute rupture of the membrane, the conductivity between the electrodes 51a and 51b changes when the bubble that has passed through the rupture portion of the hollow fiber membrane 4 passes through the membrane rupture detection device 50. That is, when air bubbles enter between the electrodes 51a and 51b, the electrical resistance between the electrodes 51a and 51b increases. Therefore, when a constant voltage is applied between the electrodes 51a and 51b from the constant voltage power source, the current value between the electrodes 51a and 51b decreases, and if a bubble passes between the electrodes 51a and 51b, the space between the electrodes 51a and 51b. The current value of is restored.

FIG. 3 (b) shows an example of a waveform diagram obtained by converting the change in current accompanying the passage of bubbles into a change in voltage. The storage unit 55 stores this voltage change pattern. For example, the change in voltage as shown in FIG. 3B is binarized and converted into a pulse waveform, and the average value of the frequency and period of the pulse is stored.
(2) Determination of presence / absence of fine membrane rupture in apparatus with unknown membrane rupture Next, a membrane module whose membrane rupture is unknown is incorporated as shown in FIG. 1, and a filtration operation step is performed.

  When determining the fine film break, the film break detecting step and the step for determining the fine break of the film are executed. The voltage change accompanying the current change between 51a and 51b is measured. If there is no film rupture, the voltage is normally constant as shown in FIG. 3 (a), so that the determination unit 56 determines that there is no film rupture.

  When the change pattern is detected, the determination unit compares the detected change pattern with the stored change pattern to determine whether or not the film is broken. For example, if the period and frequency of the pulse pattern obtained by binarizing the voltage change are within a predetermined range determined based on the stored average value, it is determined that there is a film rupture. If the film is not broken,

  In addition, since the determination of membrane breakage is made by comparing the change patterns in this way, even if there is a voltage change due to disturbance such as fluctuations in raw water quality, it is not judged that the membrane is broken, and the judgment accuracy is extremely high. Become.

  In this description, a change is measured by passing a current between the electrodes 51a and 51b with a constant voltage power supply. However, a change in the applied voltage accompanying the passage of a bubble is caused when a constant current is passed between the electrodes 51a and 51b with a constant current power supply. The film breakage may be determined from the change pattern.

Alternatively, the electrical conductivity between the electrodes 51a and 51b may be measured, and film breakage may be determined based on the change pattern of the electrical conductivity.
(3) It should be noted that the output pattern of the detection device is stored in the same manner as in (1) above for the medium-scale known device for film breakage and the large-scale known device for film breakage, and this output pattern is used. A medium-scale or large-scale film break may be detected for an apparatus with an unknown film break.
<Second Embodiment>
Hereinafter, a detection example of membrane breakage when a membrane breakage exists in the external pressure type hollow fiber membrane separation device will be described.
[Description of State in External Pressure Hollow Fiber Membrane Module 1 ′ when Fine Membrane Breaks Occur]
Below, the state in the external pressure type hollow fiber membrane module 1 ′ when a fine membrane breakage such as a pinhole has occurred will be described in more detail. FIG. 6 (a) is a partial cross-sectional view for explaining a state in the film processing apparatus in which gas breakage is detected by supplying gas to the outside of the film, and FIG. 6 (b) is for determining whether the film is finely broken. It is a fragmentary sectional view explaining the state in the film | membrane processing apparatus of FIG. 1 in the process to perform.

  In the external pressure type hollow fiber membrane separation apparatus of FIG. 6, the external pressure type hollow fiber membrane module 1 ′ has substantially the same configuration as that of FIG. The upper side of the stopper 8 is a treated water chamber 14 ', and the lower side of the sealing material 8 is a raw water chamber 12'. In addition, a membrane breakage detection device 50 is provided in the upper pipe of the treated water chamber 14 '. The nozzle 12a is used as a raw filter water inlet.

  As shown in FIG. 6 (a), in the membrane breakage detection step, part of the pressurized gas supplied to the outside of the hollow fiber membrane 4 leaks (invades) from the fine breakage portion 4c to the inside of the hollow fiber membrane 4. To do. This leaked gas adheres to the inner surface of the hollow fiber membrane 4 as air bubbles due to surface tension.

  Thus, since air bubbles adhere to the inner surface of the hollow fiber membrane 4, the air bubbles are not detected by the membrane breakage detection device 50.

  Thereafter, as shown in FIG. 6 (b), when raw water is supplied to the raw water chamber 12 ′, a part of the raw water permeates through the membrane wall of the hollow fiber membrane 4, and the inside of the hollow fiber membrane 4 from the inner surface of the hollow fiber membrane 4. Flow into. Then, the bubbles adhering to the inner surface of the hollow fiber membrane 4 are pulled away from the inner surface by the treated water flowing from the inner surface of the hollow fiber membrane 4.

  The separated air bubbles ride on the flow of the treated water and rise inside the hollow fiber membrane 4, and further move to the membrane breakage detecting device 50 through the treated water chamber 14 'and the pipe on the upper side thereof. Detected by device 50.

Thus, since the membrane breakage was detected when the raw water supply was resumed, it is determined that a fine membrane breakage has occurred.
[Description of State in External Pressure Type Hollow Fiber Membrane Module 1 ′ When Medium or Large Scale Membrane Breakage Occurs]
Next, the state in the external pressure type hollow fiber membrane module 1 ′ in the case where a medium-scale or larger membrane breakage such as one or more hollow fiber membranes 4 is broken will be described in detail with reference to FIG. explain. FIG. 7 is a partial cross-sectional view for explaining the state in the film processing apparatus in the film breakage detecting step.

  As shown in FIG. 7, when the hollow fiber membrane 4 has a medium-sized or larger fracture portion 4 d such as a tear, a relatively large amount of air bubbles leak into the hollow fiber membrane 4 from the fracture portion 4 d in the membrane fracture detection step. To do. This bubble rises inside the hollow fiber membrane 4, further moves to the membrane breakage detection device 50 through the treatment water chamber 14 ′ and the piping above it, and is detected by this membrane breakage detection device 50.

  Thus, since the film break was detected in the film break detection step, it is determined that the film break is medium or larger.

In this example as well, if a film break is detected during cleaning with the air / water mixture, it is determined that a large-scale film break has occurred.
<Another configuration example of the membrane breakage detector>
In the present invention, the electrodes such as the electrodes 51a and 51b may be installed by using a piping member for water flow. In this way, the configuration of the film breakage detection device is simplified.

  FIG. 8 is a sectional view of the vicinity of an elbow as a piping member having such a configuration. FIG. 8 shows a constant voltage type film breakage detection circuit diagram in which a dry battery is used as a constant voltage source and a change in the current flowing between the electrodes is amplified and detected by a transistor.

  In FIG. 8, a resin joint 64 is connected to a stainless elbow 63. A needle electrode 65 is inserted into a hole 66 provided in the resin joint 64, and the electrode 65 is fixed to the hole 66 by an adhesive 67. The tip of the electrode 65 protrudes from the inner wall of the resin joint 64.

A stainless elbow 63 is connected to the base of the NPN transistor T and used as an electrode. The collector of the transistor T is connected to the electrode 65 via the resistors R ₂ and R ₁ . The emitter of the transistor T is connected to the cathode of the dry battery 68. The anode of the battery 68 is connected to a point between said resistors R ₁ and R _2. Voltmeter V is provided to measure the voltage drop across the resistor R _2. A constant voltage is applied from the dry battery 68 between the elbow 63 and the electrode 65. When only water flows through the elbow 63, the current value between the elbow 63 and the electrode 65 is constant, but when the bubble passes through the elbow 63, the current value decreases. This current change is amplified by the transistor T, a collector current changes in the transistor T, the voltage across the resistor R ₂ that is detected by the voltmeter V varies. From the change in the detection voltage of the voltmeter V, the passage of bubbles in the elbow 63 is detected. In particular, in the detection mechanism shown in FIG. 8, since the value of the current flowing through the electrode 65 changes greatly when the bubble contacts the needle electrode 65, the bubble can be detected sensitively.
<Other aspects>
In the above embodiment, there is one membrane module 1, but there may be two or more. When there are a plurality of membrane modules, one compressor C and one membrane breakage detection device 50 may be provided for each module, or they may be shared. The membrane break detection procedure for each membrane module when the compressor C and the membrane break detection device 50 are shared is, for example, as follows.

  The pressurized gas from the compressor C is introduced only into the first membrane module, and the presence or absence of membrane rupture is detected by the membrane rupture detection device in the membrane rupture detection step and the membrane fine rupture step. After the membrane rupture detection of the first membrane module is completed, the introduction of the pressurized gas to the first membrane module is stopped, and then the pressurized gas is introduced only to the second membrane module. The device detects the presence or absence of film breakage. Similarly, the membrane breakage of the third membrane module to the last membrane module is sequentially detected.

  When the occurrence of film breakage is detected, for example, a warning lamp in the management room blinks, and the maintenance manager is notified of which film module has broken. Upon receiving the notification, the maintenance manager stops the operation of the membrane module in which the membrane breakage occurs, replaces the membrane module with a new one, and resumes normal operation. Repair the membrane module that has been broken and reuse it.

  In the above embodiment, the hollow fiber membrane is used as the membrane, but the membrane is not limited to this and may be, for example, a spiral membrane.

  A test example in which the presence or absence of film breakage is detected using the film processing apparatus of FIG. 1 will be described below.

A hollow fiber membrane 4 having an inner diameter of 1150 μm, an outer diameter of 1900 μm, a length of 1000 mm, a molecular weight cut off of 13000, and an effective membrane area of 0.14 m ² was used. As the conductivity meter, the one shown in FIG. 8 was used. Resistor R ₁ is 1 kΩ, R ₂ is 22 kΩ, and the dry battery is 9V.

  In the membrane treatment apparatus having the above configuration, after performing the filtration step as described in the first embodiment for several minutes, the raw water pump P is stopped, the compressor C is operated, and only the gas is passed through the hollow fiber membrane. Module 1 was supplied.

Then, stop the compressor C, and by operating the raw water pump P, and the voltage generated in the resistor R ₂ was measured by a voltmeter V. FIG. 3 (a) is a graph showing the change over time of the voltage in the membrane module in which it was confirmed that the hollow fiber membrane was not cut.

Next, after providing a pinhole having a diameter of about 80 μm in one hollow fiber in advance, the same filtration step, membrane rupture detection step, and step of judging micro-breakage of the membrane are performed. In the determination step, the voltage generated at the resistor R ₂ was measured by a voltmeter V. The results are shown in FIG. 3 (b).

  As shown in FIGS. 3 (a) and 3 (b), when the film is broken, the detection voltage of the voltmeter V is changed and the film breakage is detected.

It is a schematic diagram of the film processing apparatus concerning an embodiment. It is a block diagram of the film | membrane fracture | rupture detection apparatus integrated in the film | membrane processing apparatus of FIG. (A) is a figure which shows the time-dependent change of the voltage when the hollow fiber membrane is not cut | disconnected, (b) is a figure which shows the time-dependent change of the voltage when the hollow fiber membrane is fractured. It is a figure explaining the example of a film break detection when the fine film break has arisen in the film processing apparatus of FIG. FIG. 2 is a diagram for explaining an example of film breakage detection when a medium-scale film break occurs in the film processing apparatus of FIG. 1. It is a figure explaining the example of film | membrane fracture | rupture detection when the fine film | membrane fracture | rupture has arisen in the external pressure type film processing apparatus. FIG. 7 is a diagram for explaining an example of film breakage detection when a medium-scale film break occurs in the film processing apparatus of FIG. 6. It is sectional drawing which shows another structural example of a film | membrane breakage detection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal pressure type hollow fiber membrane module 2 Casing 4 Hollow fiber membrane 6,8 Sealing material 10 Raw water chamber 12 Treated water chamber 12a, 12b, 12c, 12d Breaking part 12A Dead end part 14 Circulating water chamber 20 Raw water tank 40 Treated water layer 50 Film breakage detector 51a, 51b Electrode 63 Stainless steel elbow 65 Electrode

Claims (8)

A method for operating a membrane treatment apparatus having a membrane for filtering a liquid to be treated,
A filtration operation step of supplying a liquid to be treated to one side separated by a membrane and taking out the treatment liquid from the other side;
In the operating method of the film processing apparatus for performing a film rupture detection step of supplying a pressurized gas to the one side and detecting a film rupture by detecting a gas flowing out to the other side by a detection means,
After the film breakage detection step, when a liquid is supplied to the one side, it is determined that a minute breakage has occurred in the film when gas is detected by the detection means. Driving method.   In claim 1, when gas is detected by the detection means in the film rupture detection step, it is determined that the film is ruptured. When the gas is not detected, liquid is supplied to the one side after the film rupture detection step. A method of operating a film processing apparatus, wherein a determination of microfracture is made based on whether or not it is detected. In claim 1 or 2, prior to the film rupture detection step, performing a cleaning step of cleaning the membrane by supplying a gas-liquid mixture to the one side,
At this time, when gas is detected by the detection means, it is determined that a large-scale film break has occurred,
In this case, when the gas is not detected, the film breakage detecting step of supplying the pressurized gas is performed.   4. The method for operating a membrane treatment device according to claim 1, wherein the membrane treatment device is an internal pressure type hollow fiber membrane separation device.   4. A method for operating a membrane treatment apparatus according to claim 1, wherein the membrane treatment apparatus is an external pressure type hollow fiber membrane separation apparatus.   6. The method according to claim 1, wherein when the film breakage is detected, the electric resistance of the liquid on the other side separated by the film is measured, and the gas is detected based on the change in the electric resistance. A method for operating a membrane processing apparatus.   7. The electrode according to claim 6, wherein a pair of electrodes is disposed so as to be in contact with the liquid on the other side separated by the film, a voltage is applied between the electrodes, and a change in voltage, current, or conductivity between the electrodes. An operation method of a film processing apparatus, wherein the occurrence of film breakage is detected from the pattern. 8. The gas processing apparatus according to claim 7, wherein a gas or gas / liquid mixture is circulated through a film processing apparatus in which the film is broken to detect a change pattern of the voltage, current, or conductivity, and the change pattern is stored in a storage means. ,
A gas or gas-liquid mixture is circulated through a membrane processing apparatus whose membrane breakage has not been confirmed to detect the voltage, current, or conductivity pattern, and this pattern is compared with the change pattern stored in the storage means. A method for operating a film processing apparatus, wherein the presence or absence of a film is determined.

Images