JP2008296087A - Method for detecting damage in membrane, and membrane filter device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly accurate method of detecting damage in a membrane at a low cost with improved detection sensitivity, and to provide a membrane filter device. <P>SOLUTION: The method of detecting damage in a membrane for use in a membrane filter device constituted of a raw water supply means 20 for supplying raw water, a membrane filter means for obtaining filtrate water from raw water supplied thereto, and a back-washing water supply means 40 for supplying the membrane filter means with a portion of filtered water as water for back-washing is characterized by comprising the process of preparing microbubble-containing water as a source of suspended matters by injecting a gas into a liquid flow path to admix the gas with a liquid flowing into the raw water supply means 20 or into the back-washing water supply means 40 via the liquid flow path, the process of measuring the state of the suspended matters in effluent discharged out of the membrane filter means from the microbubble-containing water supplied thereto via the liquid supply path, and the process of detecting a presence or an absence of damage in the membrane filter means from the above measured value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a membrane damage detection method and a membrane filtration device in a membrane filtration device.

  Conventionally, membrane filtration devices have been installed in water purification facilities that purify raw water such as groundwater and river surface water. The membrane filtration device has a membrane filtration means (hereinafter referred to as a membrane module) incorporating a filtration membrane for separating and removing turbidity, pathogenic protozoa, etc. (hereinafter collectively referred to as turbidity) contained in the raw water. The membrane module has a function of generating clear and safe filtered water. In general, a membrane filtration apparatus is configured to include a large number of membrane modules according to the amount of purified water, such as a unit system in which a plurality of membrane modules are connected in parallel or a series system in which a plurality of units are arranged in parallel. The

  In such a membrane filtration device, a filtration process, a backwashing process, a chemical washing process, etc. are repeatedly executed, and the filtration in the membrane module is caused by pressure fluctuations and membrane material deterioration associated with these processes. The film may be damaged, broken or broken (hereinafter referred to as damage). If the filtration membrane is damaged, the turbidity in the raw water directly flows out from the damaged portion, so that the filtered water is contaminated. For this reason, when filtration membrane damage occurs, it is important to quickly grasp and identify the generated membrane module, take early measures, and maintain the water purification capability of a normal membrane module that is not damaged.

  As a method for detecting damage to the filtration membrane, a method of measuring the number of bubbles in the permeated water by replacing the raw water side with air and installing a transparent tube and a transmissive photoelectric detector on the permeate side for the external pressure membrane module (for example, Patent Document 1) and a system (for example, Patent Document 2) in which backwash air is injected from the transmission side and a transparent tube and a photoelectric detector are installed to measure the presence or absence of bubbles in the permeated water are known. Further, a method of supplying pressurized air to the sealed raw water side filled with raw water and measuring bubbles in the treated water with a fine particle monitor (for example, Patent Document 3), or a gas or gas-liquid mixture from the internal pressure type raw water side. There is a method of determining the presence or absence of bubbles by measuring the electrical resistance of the permeate (for example, Patent Document 4). Furthermore, a method of adding bubbles to the raw water upstream of the membrane filtration means (for example, Patent Document 5), or supplying pressurized water in which air is dissolved to the raw water to generate micro air, and measuring the number of bubbles in the permeated water Then, there is an air injection method such as a method for detecting damage (for example, Patent Document 6).

JP 2000-342937 A JP 2003-144866 A JP-A-8-173774 JP 2005-349253 A JP 2007-7567 A JP 2003-1112018 A

By the way, in the above-described Patent Document 1, the external pressure type raw water side is replaced with air, and generally, the external pressure type membrane module has a volume on the raw water side set several times larger than the permeate side, It takes time to replace it, and the detection is delayed, while the filtered water production is interrupted. Furthermore, since raw water is drained and replaced, there is a problem that the water recovery rate of the entire process is lowered.
Further, there are various cases of damage to the filtration membrane, such as desorption, cutting, small laceration, and pinhole, and the damage area also changes depending on the damage state. In the above-mentioned Patent Documents 1 to 4, consideration is not given to the bubble diameter of the gas to be supplied, and depending on the type and degree of damage (degree of damage area), it becomes difficult to detect or time is required to detect. There is a problem of needing.
In this regard, in Patent Documents 5 and 6 described above, bubbles or air-dissolved pressurized water is added to the raw water to cope with these problems. However, Patent Document 5 requires a large facility for generating and storing bubbles to be added in advance. Moreover, since the filtration membrane is suddenly damaged, it is necessary to always generate and store bubbles. Also in Patent Document 6, a new high-pressure facility for generating and storing air-dissolved pressurized water is required, and a considerable amount of energy is also required because water is pressurized until air is dissolved. As described above, in the method of adding bubbles or air-dissolved pressurized water, there is a problem that equipment and operating costs increase.

  The present invention does not require the storage of bubbles by equipment, and can effectively use the current equipment to quickly generate micro-aerated water and supply it directly to the membrane filtration means to improve the detection sensitivity of filtration membrane damage. The object is to provide a highly accurate membrane damage detection method and membrane filtration device at low cost.

As a means for solving the above-mentioned problems, the present invention generates micro-aerated water using raw water or backwash water and its supply means, and directly performs membrane filtration using the generated micro-aerated water as a turbidity source. The occurrence of damage and the damaged filtration membrane are specified based on the turbid state of the discharged water supplied to the means and discharged from the membrane filtration means.
Here, the discharged water includes discharged water discharged by backwash water in addition to the permeated water obtained through the membrane filtration means.

  According to the present invention, it is not necessary to store air bubbles by equipment, and it is possible to rapidly generate micro-aerated water by effectively using the current equipment and directly supply it to the membrane filtration means to improve the detection sensitivity of filtration membrane damage. Thus, a highly accurate membrane damage detection method and membrane filtration device can be obtained at low cost.

Next, the membrane filtration device of the present invention will be described in detail by taking a membrane filtration device provided with an internal pressure type membrane module as an example.
(First embodiment)
As shown in FIG. 1, the membrane filtration device 1 of the present embodiment is mainly composed of a membrane module 10, raw water supply means 20, a filtration water tank 30, backwash water supply means 40, microbubble generation means 50, turbidity measurement means 60, Damage determination means 70 is provided.

  The membrane module 10 includes raw water chambers 11 and 12 at the top and bottom, and a permeate water chamber 13 is disposed between the raw water chambers 11 and 12. The permeated water chamber 13 is provided with a filtration membrane 14 in which approximately several thousand hollow fiber membranes are mounted. The ends of the hollow fiber membrane constituting the filtration membrane 14 are connected to the raw water chambers 11 and 12. It is provided so as to open. Here, the raw water chambers 11 and 12 and the permeate water chamber 13 are partitioned by fixed walls 15a and 15b, respectively, and the raw water chambers 11 and 12 and the permeate water chamber 13 only through the built-in filtration membrane 14. The liquid flows between them.

  The raw water chamber 12 is connected to a raw water pipe 3 to which raw water is supplied via an on-off valve 2, and the raw water chamber 11 is connected to a discharge pipe 5 through which backwash water is discharged via an on-off valve 4. Yes. In addition, a filtered water pipe 6 that guides filtered water obtained from the membrane module 10 to the filtered water tank 30 is connected to the upper part of the permeate water chamber 13.

  The upstream side of the raw water pipe 3 leads to a raw water intake area such as groundwater or river surface water, and a raw water supply means 20 including a high-speed rotating pump or the like is interposed upstream of the on-off valve 2. The raw water pipe 3 is provided with a gas-liquid mixing means 52 of the microbubble generation means 50 on the upstream side of the raw water supply means 20.

  The microbubble generation unit 50 includes an air supply unit 51, a gas-liquid mixing unit 52, and the raw water supply unit 20 described above. The air supply means 51 has an intake port (not shown) for sucking outside air and supplies outside air (air) to the gas-liquid mixing means 52. Note that when the fine bubbles generated by the fine bubble generating means 50 are generated by a gas other than air, the intake port is opened in a desired gas. The gas-liquid mixing means 52 has a function of generating gas mixed liquid by mixing gas with raw water (liquid) supplied through the raw water pipe 3, and may be, for example, a line mixer, If the means of the venturi structure to reduce is applied, the pushing pressure of the air supply means 51 can be reduced. The gas mixture liquid generated by the gas-liquid mixing means 52 is in a state where the bubbles are refined by the rotation and shearing force of the raw water supply means 20 on the downstream side, thereby obtaining microbubble water. Here, by adjusting the supply ratio of the raw water and air by the air supply means 51 or the like, it is possible to generate fine bubbles that are homogeneous, flow along the flow of the raw water, and do not easily float.

The discharge pipe 5 serves to discharge the backwash water supplied to the membrane module 10 by opening the on-off valve 4 provided in the middle of the backwash process described later.
The filtered water pipe 6 guides filtered water to the filtered water tank 30 via the on-off valve 7, and a turbidity measuring means 60 is disposed in the vicinity of the connection port with the upstream membrane module 10.

  The turbidity measuring means 60 measures the turbidity state of the permeated water (discharged water) obtained from the membrane module 10 and is not particularly limited, but known in the art such as ultrasonic waves, photoelectric, acoustic, and electrical resistance. It is comprised with the sensor using the means of. The measurement value obtained by the turbidity measurement means 60 is input to the damage determination means 70.

  The damage determination means 70 is a diagnostic device composed of a personal computer or the like, and determines whether or not the filtration membrane 14 of the membrane module 10 is damaged based on the measurement value input from the turbidity measurement means 60. For example, in the normal filtration mode described later, the damage determination means 70 determines whether or not the measured value exceeds a preset threshold value, or whether the time-series change gradient of the measured value is equal to or greater than a predetermined gradient. Whether or not the filtration membrane 14 is damaged is determined (detected) by determining whether or not the value is higher than the latest measured value.

  The damage determination means 70 outputs a determination signal to the control device 71 when it is determined that the filtration membrane 14 is damaged. When the control device 71 inputs a determination signal for damage to the filtration membrane 14 from the damage determination means 70, an operation signal for stopping the operation of the membrane filtration device 1 is sent to the membrane filtration device 1 (raw water supply means 20 or the like). The operation of the membrane filtration device 1 is stopped by outputting, and the membrane filter 14 is prepared for replacement.

  The filtered water tank 30 is provided with a backwash water supply means 40 and an open / close valve 41, and a backwash water pipe 8 connected to the filtered water pipe 6 is inserted therein.

Next, the normal driving | operation operation | movement of the membrane filtration apparatus 1 comprised in this way is demonstrated with reference to FIG. Usually, the membrane filtration apparatus 1 is configured to repeatedly execute three steps of a filtration step (S1), a backwashing step (S2), and a flushing (rinse washing) step (S3).
First, in the filtration step (S1), the open / close valve 2 of the raw water pipe 3 and the open / close valve 7 of the filtered water pipe 6 are opened, the other open / close valves 4 and 41 are closed, and the raw water supply means 20 is operated. Then, raw water containing turbidity is supplied to the raw water chamber 12 of the membrane module 10. The raw water is trapped and removed from the turbidity on the inner surface (upstream side) of the filtration membrane 14 and passes through the permeate chamber 13 outside (downstream side) of the filtration membrane 14. The permeated clear raw water (hereinafter referred to as permeate) is stored in the filtrate tank 30 through the filtrate pipe 6 connected to the permeate chamber 13. Most of the stored permeated water is supplied to tap water as purified water.

  If such a filtration process (S1) is performed for a predetermined time, it will move to a backwashing process (S2). In the backwashing step (S2), the raw water supply means 20 is stopped, the open / close valve 4 of the discharge pipe 5 and the open / close valve 41 of the backwash water pipe 8 are opened, and the other open / close valves 2 and 7 are closed. The backwash water supply means 40 is activated. When the backwash water supply means 40 is operated, the filtrate stored in a certain amount in the filtered water tank 30 is supplied from the backwash water pipe 8 to the permeated water chamber 13 of the membrane module 10 through the filtered water pipe 6. Then, filtrate water permeates from the outside of the filtration membrane 14 to the inside of the filtration membrane 14, and then is discharged to the raw water chamber 11 side and is discharged from the raw water chamber 11 to the outside through the discharge pipe 5. After the back washing step (S2) is completed, the process proceeds to the rinsing washing step (S3).

  In the rinse cleaning step (S3), after the backwashing step (S2) is completed, the backwashing water supply means 40 is stopped, the open / close valve 2 of the raw water pipe 3 and the open / close valve 4 of the discharge pipe 5 are opened. The on-off valves 7 and 41 are closed to operate the raw water supply means 20. In this step, the raw water supplied to the raw water chamber 12 is discharged from the discharge pipe 5 through the raw water chamber 11 without passing through the filtration membrane 14. Thereby, the membrane surfaces of the raw water chambers 11 and 12 and the filtration membrane 14 are washed.

  The cycle from the filtration step (S1) to the rinse washing step (S3) as described above is defined as one cycle, and after the rinse washing step (S3) is completed, the process proceeds to the filtration step (S1). These operation operations are referred to as a normal filtration mode, and the control device 71 instructs the time required for each process, the timing of operation / stop of various means, and opening / closing operations.

Next, the film damage detection operation will be described. First, a film damage detection operation that is performed by periodically switching the normal filtration mode to the film damage detection mode according to a command from the control device 71 will be described.
As shown in FIG. 3, the membrane damage detection mode is switched when the filtration step (S1) in the normal filtration mode is completed. In the permeation / detection step (S4), in the operation state of the filtration step (S1), the microbubble generation means 50 is operated to supply air from the air supply means 51 to the gas-liquid mixing means 52, and the raw water supply means 20 Is used to generate bubble-mixed raw water and pass through the raw water supply means 20 to generate micro-bubble water (step of generating micro-bubble water as a turbidity source).

  When the microbubbled water generated in this way is supplied to the raw water chamber 12 of the membrane module 10, if the filtration membrane 14 is damaged, the fine bubbles that flow along with the raw water also pass through the damaged portion. It will flow out together to the chamber 13 side. According to the experimental findings of the present inventors, the damaged portion is in a state where the membrane resistance becomes extremely small or almost disappears, and the outflow amount increases in proportion to the amount of water permeated from the normal portion. It becomes a state. In addition, it was found that when the operation of reducing the supply amount of raw water was performed, the outflow ratio from the damaged part could be increased. For these reasons, the supply amount of raw water may be reduced to increase the amount of fine bubbles in the entire permeated water so that damage to the filtration membrane 14 can be easily detected.

  And the turbid state of filtrate water is measured in the turbidity measurement means 60 installed in the filtered water pipe 6 (process of measuring the turbid state of the discharged water discharged | emitted from the membrane filtration means 10). The measurement value by the turbidity measurement means 60 is input to the damage determination means 70, and the presence or absence of damage to the filtration membrane 14 is determined based on the measurement value (step of detecting the presence or absence of damage). For example, the measured value is compared with the measured value of the turbid state in the latest normal filtration mode to determine whether or not the absolute value of the difference is within a predetermined threshold (within range). When the measured value exceeds a predetermined threshold value, it is determined that the filtration membrane 14 is damaged. Based on this determination, the damage determination means 70 outputs the presence / absence of damage and a warning of damage to a display device or alarm device (not shown) and instructs the control device 71 about the next operation in the membrane filtration device 1. do. As the turbidity state, corresponding to the sensor applied to the turbidity measuring means 60, each value such as turbidity, the number of particles, light / ultrasonic attenuation / reflection / scattering amount, electric power / current value, and the like is indicated. Can be.

  In the treatment step (S5), the control device 71 executes the next operation of the membrane filtration device 1 based on the output information from the damage determination means 70. For example, when the filtration membrane 14 is not damaged, the operation is switched to the normal filtration mode and the operation is performed from the backwashing step (S2). On the other hand, if it is determined that damage has occurred, the membrane filtration device 1 is stopped, and the replacement of the membrane module 10 and the implementation of repair work are urged. Then, after the replacement of the membrane module 10 and the repair work, the re-operation is started in the normal filtration mode. That is, the operation is restarted from the filtration step (S1).

Below, the effect acquired in this embodiment is demonstrated.
(1) Without providing a large-scale new facility, the present facility can be used effectively to generate micro-aerated water and supply it to the membrane module 10, which increases the equipment cost and running cost. It is economical.
(2) Since it is possible to quickly generate micro-aerated water and supply it directly to the membrane module 10 without requiring a large bubble storage facility, it is possible to improve the detection sensitivity of damage to the filtration membrane 14. Can do.
(3) Since the rapidly generated micro-aerated water is supplied to the membrane module 10 and damage to the filtration membrane 14 is detected, highly accurate membrane damage can be detected.
(4) Transition from the normal filtration mode to the membrane damage detection mode and periodic membrane damage detection are performed, so even if the damaged portion of the filtration membrane 14 is very small, the change in measured value over time It is possible to reliably detect that the filtration membrane 14 has been damaged by performing an operation such as recording (storing) it.

  In the above example, the membrane damage detection mode is periodically executed. However, as shown in FIG. 4, the turbidity measurement means (permeate turbidity state measurement means) 60 in the filtration step (S1) in the normal filtration mode. The damage determination means 70 determines whether or not the film damage detection interrupt determination is necessary based on the measured value from the above, and if it is determined that the interrupt is necessary, the damage determination means 70 temporarily Alternatively, the film damage detection mode may be executed.

  In FIG. 4, in the filtration step (S1), when the measured value from the turbidity measuring means 60 is higher than a preset threshold value (predetermined value) (if abnormal, S1 ′), the film damage is detected. The mode is shifted to the transmission / detection step (S4). The operation procedure in the film damage detection mode is the same as the operation procedure (see FIGS. 2 and 3). Further, in the filtration step (S1), the measured value from the turbidity measuring means 60 is reversed as usual within the range of the preset threshold value (predetermined value) (when normal, S1 ′). It transfers to a washing process (S2) and normal filtration mode is continued. In addition to the above-described example, whether interruption is necessary is determined to be necessary when, for example, the time-series change gradient of the measurement value of the turbidity measuring means 60 is equal to or greater than a predetermined gradient. It can also be configured.

  According to such a membrane filtration device 1, the film damage detection mode is shifted to the membrane damage detection mode only when necessary based on the measurement value from the turbidity measuring means 60. Compared with the case of shifting to the detection mode, the generation efficiency of filtrate water is increased, and an efficient membrane filtration operation can be realized.

  5 and 6 show another configuration example of the microbubble generation means 50. FIG. The example shown in FIG. 5 is different from the above example in that a fine plate 53 having pores is provided on the downstream side of the raw water supply means 20. The micronized plate 53 has, for example, at least one pore having a diameter of 1 mm or less, and allows microbubbled water from the raw water supply means 20 to flow out from the pore. Thereby, micro-aerated water having finer bubbles is generated, and it is difficult to float, and fluidity with raw water is improved. By supplying such microbubbled water to the membrane module 10, the self rising bubbles are reduced, and the detection sensitivity at the time of damage can be further increased.

  6 shows that the raw water supply means 20 is provided with a branch pipe 21 (branch path), the branch pipe 21 is provided with an air supply means 51 and a gas-liquid mixing means 52, and a micronized plate 53 is provided. And different. The branch pipe 21 is provided with the raw water supply means 22 for the branch pipe 21 on the upstream side of the micronization plate 53, and the on-off valve 2 ′ is provided on the upstream side of the junction with the raw water pipe 3. Has been. A pump rotating at high speed is used as the raw water supply means 22.

  In such a configuration, the on-off valve 2 ′ is closed in the normal filtration mode, and the air supply means 51 and the raw water supply means 22 are also stopped. In the membrane damage detection mode, the on-off valve 2 ′ is opened to operate the raw water supply unit 22 and the air supply unit 51 to generate gas / liquid mixed raw water. The bubble-mixed raw water is made into fine bubble water by rotating the raw water supply means 22 and the shearing force to form fine bubble water, and is further generated as ultrafine fine bubble water by the fine plate 53. The generated micro-aerated water contains, for example, a large number of bubbles having an average diameter of several tens to hundreds of μm. Since the branch pipe 21 is connected to the raw water pipe 3 in the vicinity of the membrane module 10, the microbubble water is directly supplied to the membrane module 10.

  In this example, the raw water supply means 20 may be stopped when in the membrane damage detection mode. Thus, when the raw water supply means 20 is stopped, since there is no dilution of the microbubble water by the raw water, it becomes dense microbubble water, and as a result, the detection sensitivity at the time of membrane damage can be improved. The raw water supply means 22 may be replaced with a normally installed spare machine or may be newly installed with a smaller capacity, and there is an advantage that microbubble water can be generated quickly and inexpensively.

(Second Embodiment)
Next, the membrane filtration apparatus 1 ′ according to the second embodiment of the present invention will be described.
As shown in FIG. 7, the membrane filtration device 1 ′ of the second embodiment is different from the above-described embodiment in that the membrane filtration device 1 ′ is an external pressure type membrane module 10 ′, and only the configuration of the membrane module 10 ′ is different. The raw water supply system and the filtration / backwash water system have substantially the same structure as the internal pressure type described above. In the following description, the same parts as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The membrane module 10 'is provided with permeated water chambers 13a and 13b at the top and bottom, the raw water chamber 11 is disposed between the permeated water chambers 13a and 13b, and the filtration membrane 14 is hollow fiber in the permeated water chambers 13a and 13b. It arrange | positions so that the both ends of a film | membrane may open. The permeated water chambers 13 a and 13 b and the raw water chamber 11 are partitioned by fixed walls 15 a and 15 b, and the discharge pipe 5 is installed above the raw water chamber 11. A filtered water pipe 6 provided with a turbidity measuring means 60 is connected to the upper permeate water chamber 13a, and a backwash water pipe 8 provided with a backwash water supply means 40 and an open / close valve 41 is connected to the filtered water pipe 6. Is done. The generation of microbubble water is performed by the microbubble generator 50 having the same configuration as that shown in FIG.

  Also in the membrane filtration device 1 ′ using such an external pressure type membrane module 10 ′, when the membrane damage detection mode is executed, microbubbled water is generated using raw water, and the turbid state of the permeate is changed to turbidity. A detection method similar to that of the internal pressure type measured by the measuring means 60 can be applied, and the same effect as in the above embodiment can be obtained.

(Third embodiment)
Next, the membrane filtration apparatus 100 of 3rd Embodiment of this invention is demonstrated. As shown in FIG. 8, this embodiment is an example for a membrane filtration facility in which a plurality of the membrane modules 10 (see FIG. 1) are installed. The plurality of membrane modules 10a to 10n provided are of the internal pressure type and have the same configuration as that described in the first embodiment. The piping system includes raw water branch pipes 3a ′ to 3n ′ connected to the membrane modules 10a to 10n, drain water branch pipes 5a to 5n, and filtrate water branch pipes 6a to 6n. The raw water branch pipes 3a 'to 3n' are connected to the raw water pipe 3 through the on-off valves 3a to 3n, and the drain water branch pipes 5a to 5n are connected to the open / close valves 4a to 4n on the way. The filtered water branch pipes 6a to 6n are connected to the filtered water pipe 6 through an on-off valve (not shown).

  At the upstream of the raw water pipe 3, a microbubble generating means 50 having the same configuration as that shown in FIG. 6 is provided. Moreover, the turbidity measurement means 60a-60n similar to the said turbidity measurement means 60 is installed in each filtrate water branch pipe 6a-6n, The filtrate water pipe 6 which these filtrate water branch pipes 6a-6n merged. Is provided with a combined water turbidity measuring means 65.

  Here, as the combined water turbidity measuring means 65, a highly sensitive turbidimeter or fine particle sensor capable of measuring turbidity of 3 to 4 digits of decimal point and the number of fine particles of several tens by a laser method is used. Since such combined water turbidity measuring means 65 is relatively expensive, it is installed at a rate of one unit in the membrane filtration device 100 and monitors (manages) the entire filtrate water of the membrane filtration device 100 by measurement. It is installed for the purpose. On the other hand, the turbidity measuring means 60a to 60n are set to be lower in measurement accuracy than the combined water turbidity measuring means 65, and are relatively inexpensive. The turbidity measuring means 60a to 60n are installed for the purpose of individually monitoring (managing) the permeated water of the membrane modules 10a to 10n by measurement. In other words, depending on the turbidity state of the raw water, even if the turbidity measuring means 60a to 60n cannot measure the abnormality until the abnormality is detected, the combined water turbidity measuring means 65 can detect this. .

The membrane damage detection operation in such a membrane filtration device 100 will be described. The basic operation is the same as the operation described with reference to FIG. 4 in the above embodiment, and will be described here with reference to FIG. 4 as appropriate.
In this membrane filtration device 100, the damage determination means 70 inputs the measurement value of the combined water turbidity measurement means 65 constantly or every predetermined time, and the input measurement value exceeds a preset threshold value (predetermined value). Whether or not the permeated water state is abnormal (Fig. 4 (S1 ')), or the time-series change gradient of the measured value (including the increasing gradient with the latest measured value) is greater than or equal to a predetermined gradient It is determined whether or not there is an abnormality, and when it is determined that there is an abnormality, the process proceeds to the film damage detection mode and proceeds to the transmission / detection step (FIG. 4, S4). Here, since the measurement value of the combined water turbidity measuring unit 65 relates to the entire combined filtrate, the damage determination unit 70 damages any of the membrane modules 10a to 10n of the membrane filtration device 100. Is determined to have occurred.

  In the permeation / detection step (S4 in FIG. 4), the raw water supply means 20 is stopped and the on-off valve 2 is closed, and then the on-off valve 2 'is opened to activate the microbubble generation means 50. The microbubble water is supplied to all the membrane modules 10a to 10n, and the turbid state of the permeated water is measured by the turbidity measuring means 60a to 60n. The measured values of the turbidity measuring means 60a to 60n are output to the damage determining means 70, and specify those that show a higher measured value than other measured values, or specify that the measured value shows an increasing tendency. The membrane modules 10a to 10n corresponding to the turbidity measuring means 60a to 60n are specified as having caused membrane damage. The damage determination means 70 outputs a display indicating whether or not there is damage, a warning that there is damage, a display that identifies the damaged membrane modules 10a to 10n, and the like, and instructs the control device 71 to perform a driving operation.

  In the treatment step (FIG. 4, S5), the control device 71 executes the next operation of the membrane filtration device 100 based on the output information from the damage determination means 70. When it is determined that no damage has occurred, the operation mode is switched to the normal filtration mode, and the operation is performed so as to start from the backwashing step (FIG. 4, S2). If it is determined that damage has occurred and a damaged membrane module (any one of 10a to 10n) is specified, the piping system is closed and locked. For example, when it is specified that the membrane module 10b is damaged, the on-off valves 3b, 4b and the on-off valves (not shown) provided in the filtrate branch pipe 6b are closed, and then the normal filtration mode is entered. It is switched, and it operates so that it may implement from a backwash process (FIG. 4, S2). The membrane module 10b that is locked by closing the piping system is unlocked after replacement or repair work.

Thus, even in the membrane filtration device 100 having the plurality of membrane modules 10a to 10n, the microbubble water is quickly generated at a low cost, and this is supplied to the membrane modules 10a to 10n to determine whether there is membrane damage. The damaged membrane modules 10a to 10n can be identified with high accuracy.
Moreover, even when the amount of air bubbles due to damage is very small, damage can be determined by the combined water turbidity measuring means 65, so even if the accuracy of the turbidity measuring means 60a-60n is not necessarily high, the damage Can be detected quickly.

  FIG. 9 shows a modified membrane filtration apparatus 100 '. In this example, the microbubbled water branch pipes 21a to 21n from the branch pipe 21 are connected to the membrane modules 10a to 10n and the raw water branch pipes 3a 'to 3n' between the on-off valves 3a to 3n. It is different in point. In this configuration, for example, when the measured value of the turbidity measuring means 60b shows a value higher than a predetermined threshold or when the measured value shows an increasing tendency, the damage determining means 70 causes the membrane module 10b to be damaged. It determines with having generate | occur | produced, while giving an alarm, a display, etc., and instruct | indicating the driving | operation operation of the film | membrane damage detection mode to the control apparatus 71. FIG. In the permeation / detection step (FIG. 4, S4), the raw water supply means 20 is stopped, and the on-off valves 3a to 3n installed in the raw water branch pipes 3a 'to 3n' are closed. Next, the opening / closing valve 2b 'of the microbubbled water branch pipe 21b of the membrane module 10b is opened to operate the microbubble generating means 50.

  By this operation, the microbubble water is supplied only to the membrane module 10b which may be damaged, and thereby the presence or absence of damage can be accurately determined. The presence / absence of damage can be determined when the measured value shows a higher value than during the most recent filtration step, or when the measured value shows an increasing tendency. After the determination, the microbubble generator 50 is stopped and the on-off valve 2b 'is closed.

  In the treatment step (FIG. 4, S5), if it is determined that the damage has occurred, the on-off valves 3b, 2b ′, 4b and the filtered water branch pipe 6b of all the branch pipes 3b ′, 21b, 5b related to the membrane module 10b are provided. The provided on-off valve (not shown) is closed, and the membrane modules 10a, 10c (not shown) to 10n other than the membrane module 10b are sequentially executed from the backwashing step (FIG. 4, S2) in the normal filtration mode.

  In such a membrane filtration device 100 ′, when the measured values of any turbidity measurement means 60a to 60n become abnormal during the filtration step in the normal filtration mode (FIG. 4, S1), it is preferable to cope with it. By supplying microbubbled water only to the membrane module 10b that can be damaged, the presence or absence of damage can be accurately determined. Further, the amount of microbubbled water generated is small, and the operation time of the microbubble forming means 50 can be reduced correspondingly, which is economical.

(Fourth embodiment)
Next, the membrane filtration apparatus 200 of 4th Embodiment of this invention is demonstrated.
The present embodiment is different in that membrane damage is detected by generating micro-aerated water with backwash water. As shown in FIG. 10, the membrane filtration apparatus 200 has a plurality of external pressure type membrane modules 10a ′ to 10n ′ arranged in parallel. The membrane modules 10a ′ to 10n ′ are connected to the raw water branch pipes 3a ′ to 3n ′ branched from the raw water pipe 3, the discharge water branch pipes 5a to 5n connected to the discharge pipe 5, and the filtered water pipe 6. The filtered water branch pipes 6a to 6n are connected. The combined water turbidity measuring means 65 is installed for the filtered water pipe 6 as described in the third embodiment, and the turbidity measuring means 60a to 60n are respectively connected to the discharge water branch pipes 5a to 5a. It is arranged in the middle of 5n. The raw water branch pipes 3a 'to 3n' are provided with on-off valves 3a to 3n, the drain water branch pipes 5a to 5n are provided with on-off valves 4a to 4n, and the filtrate water branch pipes 6a to 6n are provided with them. On-off valves 6a 'to 6n' are provided.

  A branch pipe 21 is connected to the backwash pipe 8, and a microbubble forming means 50 is installed in the middle of the branch pipe 21. The downstream side of the branch pipe 21 is further branched to form microbubbled water branch pipes 21a to 21n connected to the permeated water chambers 13b of the membrane modules 10a 'to 10n', respectively. On-off valves 2a 'to 2n' are provided in the middle of the microbubbled water branch pipes 21a to 21n.

  Such membrane damage detection in the membrane filtration device 200 is executed according to the procedure shown in FIG. That is, in the filtration step (S1) in the normal filtration mode, the damage determination unit 70 determines whether the measurement value of the combined water turbidity measurement unit 65 exceeds a preset threshold value or the time series of the measurement value. If the change gradient is greater than or equal to a predetermined gradient, it is determined that any one of the membrane modules 10a ′ to 10b ′ of the membrane filtration device 200 has been damaged (S1 ′), and the membrane damage detection mode by interruption is performed. Is executed.

  If it transfers to a film | membrane damage detection mode, first, a backwash process (S6) will be performed. This backwashing step (S6) is the same step as the backwashing step (S2) in the normal filtration mode, and the raw water supply means 20 is stopped and the on-off valves 3a to 3n and the on-off valve 7 of the filtered water are closed. The on / off valves 6a 'to 6n' and the on / off valve 41 are opened, and the backwash water supply means 40 is operated. Then, filtered water flows from the filtered water tank 30 to the filtered water pipe 6 through the backwash water pipe 8, and this is supplied to all the membrane modules 1a to 1n through the filtered water branch pipes 6a to 6n, thereby washing the membrane modules 1a to 1n. . By this back washing process, the suspended matter captured by the filtration membrane 14 on the raw water chamber 11 side can be peeled and removed.

  Next, after the backwashing step (S6) is completed, the process proceeds to the transmission / detection step (S7). In the permeation / detection step, the backwash water supply means 40 is stopped and the on-off valve 41 is closed, and then the on-off valves 2a ′ to 2n ′ of the micro-bubble water splitting pipes 21a to 21n are opened to form fine bubbles. The means 50 is activated. If it does so, micro-bubble water will be produced | generated by the branch pipe 21, and this will be supplied to the permeate water chamber 13b side through the micro-bubble water branch pipes 21a-21n, and the raw | natural water chamber 11 will pass through the filtration membrane 14 from the permeate water chamber 13b side after that. Transparent to the side. This permeated water is discharged as discharged water through the discharged water branch pipes 5a to 5n.

  The turbid state of these discharged water is measured by the turbidity measuring means 60a-60n. The measurement values of the turbidity measurement means 60a to 60n are output to the damage determination means 70, and the damage determination means 70 specifies a measurement value that is higher than other measurement values, or the measurement value tends to increase. What is shown is specified, and the membrane modules 10a ′ to 10n ′ corresponding to the specified turbidity measuring means 60a to 60n are specified to be damaged. The damage determination means 70 outputs a display indicating whether there is damage, a warning indicating damage, a display for identifying the damaged membrane modules 10a 'to 10n', and the like, and outputs an operation command to the control device 71.

  Next, the process proceeds to the treatment step (S8), and the control device 71 commands the next operation of the membrane filtration device 200 based on the output information from the damage determination means 70. When damage has not occurred, the operation mode is switched to the normal filtration mode and the operation is performed so as to be implemented from the backwashing step (S2). Further, when it is determined that damage has occurred and a damaged membrane module (any one of 10a ′ to 10n ′) is specified, for example, when the membrane module 10b ′ is damaged, all of the membrane modules 10b ′ The on-off valves 2b ′, 3b, 4b, and 6b ′ are closed, and then switched to the normal filtration mode, and the operation is performed so as to be performed from the backwashing step (FIG. 11, S2). The membrane module 10b 'locked with the piping system closed is replaced and repaired, and then the lock is released.

  According to such a membrane filtration device 200, it has the external pressure type membrane modules 10a ′ to 10n ′, and the microbubbled water generated by the backwash water is used as the filtration membranes 14 of the membrane modules 10a ′ to 10n ′. Since it is pumped inward, it does not change the area of the damaged part, but rather acts in the direction of expanding the damaged part, so that the presence or absence of the damage can be ascertained reliably. In the example shown in FIG. 10, the microbubble water is supplied from the lower permeate water chamber 13b, but it may be supplied from the upper permeate water chamber 13a.

  As described above, the method for detecting the membrane damage by switching from the normal filtration mode to the membrane damage detection mode has been described, but the microbubble generation water is supplied during the filtration process in the normal filtration mode so as to detect the membrane damage. It may be configured. As a supply method, in the membrane filtration apparatus 100 shown in FIG. 8, the microbubble generation means 50 is intermittently operated at a predetermined interval to supply microbubble water intermittently. Further, in the membrane filtration devices 100 ′ and 200 shown in FIG. 9 and FIG. 10, the on-off valves 2 a ′ to 2 n ′ may be controlled to open and close sequentially, and may be executed one module at a time. Further, in the method of switching to the membrane damage detection mode when the turbid state of the permeated water is abnormal, a cylinder can be applied as the air supply means 51 because the generation frequency of microbubble water is low.

It is a figure which shows the membrane filtration apparatus which concerns on 1st Embodiment of this invention. It is explanatory drawing of the procedure in normal filtration mode. It is explanatory drawing of the procedure in normal filtration mode and film | membrane damage detection mode. It is explanatory drawing of the procedure in normal filtration mode and film | membrane damage detection mode. It is a figure which shows the other example of a microbubble water forming means. It is a figure which shows the other example of a microbubble water forming means. It is a figure which shows the membrane filtration apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows the membrane filtration apparatus which concerns on 3rd Embodiment of this invention. It is a figure which shows the membrane filtration apparatus of a modification. It is a figure which shows the membrane filtration apparatus which concerns on 4th Embodiment of this invention. It is explanatory drawing of the procedure in a film | membrane damage detection mode.

Explanation of symbols

1, 1 'membrane filtration device 3 raw water pipe 5 discharge pipe 6 filtered water pipe 10 membrane module (membrane filtration means)
14 Filtration membrane 20 Raw water supply means 21 Branch pipe (branch path)
DESCRIPTION OF SYMBOLS 30 Filtration water tank 40 Backwash water supply means 50 Fine bubble water means 53 Fine board 60 Turbidity measurement means 65 Confluent water turbidity measurement means 70 Damage determination means 100,100 ', 200 Membrane filtration apparatus

Claims (12)

Raw water supply means for supplying raw water, membrane filtration means for obtaining permeated water from the supplied raw water, and backwash water supply means for supplying a part of the permeate as backwash water to the membrane filtration means A membrane damage detection method for detecting membrane damage of the membrane filtration means in a membrane filtration device,
Mixing a gas into the liquid supply path of the raw water supply means or the backwash water supply means to generate micro-aerated water as a turbidity source;
Measuring the turbid state of the discharged water discharged from the membrane filtration means based on the microbubbled water supplied through the liquid supply path;
And a step of detecting whether or not the membrane filtration means is damaged based on the measured value. Raw water supply means for supplying raw water, membrane filtration means for obtaining permeated water from the supplied raw water, and backwash water supply means for supplying a part of the permeate as backwash water to the membrane filtration means A membrane damage detection method for detecting membrane damage of the membrane filtration means in a membrane filtration device,
A step of branching a part of the liquid supply path of the raw water supply means or the backwash water supply means and mixing gas in the branch path to generate micro-aerated water as a turbidity source;
Measuring the turbid state of the discharged water discharged from the membrane filtration means based on the micro-aerated water supplied through the branch path;
And a step of detecting whether or not the membrane filtration means is damaged based on the measured value. Raw water supply means for supplying raw water, a plurality of membrane filtration means for connecting the supplied raw water in parallel and obtaining permeated water from the supplied raw water, and permeated water obtained by the plurality of membrane filtration means A membrane damage detection method for detecting membrane damage of the membrane filtration means in a membrane filtration device including a backwash water supply means capable of being joined and supplying a part of the plurality of membrane filtration means as backwash water to the plurality of membrane filtration means There,
A step of branching a part of the liquid supply path of the raw water supply means or the backwash water supply means and mixing gas in the branch path to generate micro-aerated water as a turbidity source;
Supplying the generated micro-aerated water to the downstream side of the liquid supply path, and supplying all of the plurality of membrane filtration means;
Measuring the turbid state of the combined water discharged from each of the plurality of membrane filtration means based on the micro-aerated water supplied by the supply means;
A step of determining the presence or absence of damage of the whole of the plurality of membrane filtration means based on the measurement value of the turbidity state of the combined water;
When it is determined that there is damage in the plurality of membrane filtration means, the step of measuring the turbid state of the individual discharged water of the plurality of membrane filtration means,
And a step of identifying the damaged membrane filtration means from the plurality of membrane filtration means based on the measured value of the turbid state of the individual discharged water.   3. The micronized plate having pores is provided in the branch path, and the micronized bubble water is generated by causing the liquid to flow through the micronized plate. 4. The method for detecting film damage according to 3.   The turbid state of the obtained permeated water is measured, and when the measured value of the turbid state is a predetermined measured value, the micro-aerated water is generated. The film damage detection method according to any one of the above.   The membrane damage detection method according to any one of claims 1 to 5, wherein the microbubble water is supplied to an upstream side of a filtration membrane built in the membrane filtration means. Raw water supply means for supplying raw water, membrane filtration means for obtaining permeated water from the supplied raw water, and backwash water supply means for supplying a part of the permeate as backwash water to the membrane filtration means A membrane filtration device,
Micro-aerated water generation that is installed in the liquid supply path of the raw water supply means or the backwash water supply means, mixes the gas from the gas supply means with the liquid, and generates micro-aerated water as a turbidity source Means,
Turbidity measuring means for measuring the turbidity state of the discharged water discharged from the membrane filtration means based on the microbubbled water supplied through the liquid supply path;
A membrane filtration apparatus comprising: a damage determination unit that determines whether or not the membrane filtration unit is damaged based on a measurement value obtained by the turbidity measurement unit. Raw water supply means for supplying raw water, membrane filtration means for obtaining permeated water from the supplied raw water, and backwash water supply means for supplying a part of the permeate as backwash water to the membrane filtration means A membrane filtration device,
It is installed in a branch path provided by branching a part of the liquid supply path of the raw water supply means or the backwash water supply means, and the gas from the gas supply means is mixed with the liquid so as to be fine as a turbidity source. Micro-aerated water generating means for generating aerated water;
Turbidity measuring means for measuring the turbidity state of the discharged water discharged from the membrane filtration means based on the micro-aerated water supplied through the branch path;
A membrane filtration apparatus comprising: a damage determination unit that determines whether or not the membrane filtration unit is damaged based on a measurement value obtained by the turbidity measurement unit. Raw water supply means for supplying raw water, a plurality of membrane filtration means for connecting the supplied raw water in parallel and obtaining permeated water from the supplied raw water, and permeated water obtained by the plurality of membrane filtration means A membrane filtration device comprising backwashing water supply means capable of joining and supplying a part thereof as backwash water to all of the plurality of membrane filtration means,
It is installed in a branch path provided by branching a part of the liquid supply path of the raw water supply means or the backwash water supply means, and the gas from the gas supply means is mixed with the liquid so as to be fine as a turbidity source. Micro-aerated water generating means for generating aerated water;
Supplying the generated micro-aerated water to the downstream side of the liquid supply path, and supplying all of the plurality of membrane filtration means;
A plurality of turbidity measuring means for measuring the turbidity state of the discharged water discharged from each of the plurality of membrane filtration means based on the micro-aerated water supplied by the supplying means;
A combined water turbidity measuring means for measuring the turbid state of the combined water discharged from each of the plurality of membrane filtration means based on the micro-aerated water supplied by the supply means;
Damage determination means for determining the presence or absence of damage in the plurality of membrane filtration means based on the measurement value by the combined water turbidity measurement means;
When it is determined by the damage determination means that there is damage in the plurality of membrane filtration means, it comprises a specifying means for identifying the damaged membrane filtration means from the measured values by the plurality of turbidity measurement means. A membrane filtration apparatus characterized by that.   The membrane filtration device according to claim 8 or 9, wherein the microbubble water generation means has a micronized plate having pores.   It has a permeated water turbidity state measuring means for measuring the turbid state of the obtained permeated water, and the micro-aerated water generating means measures the measured value of the permeated water by the permeated water turbidity state measuring means. The membrane filtration device according to any one of claims 7 to 10, wherein when the value is a value, micro-aerated water is generated.   The membrane filtration device according to any one of claims 7 to 11, wherein the liquid supply path leading to the raw water side communicates with a filtration membrane built in the membrane filtration means.

Images