JP4829875B2 - Membrane damage detection method and membrane filtration device - Google Patents

Description

  The present invention relates to a membrane filtration device for filtering water to be treated and a membrane damage detection method for detecting membrane damage in a membrane filtration device.

  In recent years, threats of infectious diseases caused by chlorine-resistant protozoa such as Cryptosporidium have arisen. This Cryptosporidium has a size of about 3 to 5 μm, and is mixed in surface water such as river water and lake water, and environmental water that is raw water such as groundwater. In order to remove Cryptosporidium mixed in the raw water, a film in which fine pores capable of removing fine particle components smaller than Cryptosporidium can be used. At present, turbidity treatment of raw tap water is performed based on a guideline for setting the turbidity of tap water to 0.1 or less.

  As a countermeasure for removing protozoa such as Cryptosporidium, a water purification method using a microfiltration membrane or an ultrafiltration membrane is effective instead of the conventional sand filtration method. However, even with water purification methods using microfiltration membranes and ultrafiltration membranes, if damage occurs to a part of the membrane that filters raw tap water, the raw water flows into the permeate from this damaged part. In other words, protozoa such as Cryptosporidium may be mixed in the filtered water that has permeated the membrane. Therefore, in order to obtain high quality filtered water, it is important to quickly detect and deal with membrane damage.

  As this membrane damage detection method, there is a method in which air is supplied to the membrane module, and the membrane damage is detected from the reduced state of air pressure or the air flow rate (see Patent Document 1). Moreover, as a film | membrane damage detection method, there exists a method which processes the to-be-processed water containing a fine bubble, and detects a film | membrane damage (refer patent document 2).

  In addition, as a method for detecting membrane damage, a microparticle meter or highly sensitive turbidimeter is installed on the filtered water side of the membrane, and if the measured value exceeds the specified value, it is judged that membrane damage has occurred and an emergency stop is made. Such a method is generally used. Although this method can be continuously monitored using a general-purpose instrument, it can be used when raw water is clarified, groundwater with low turbidity and fine particle count, or when many membrane modules are managed with a small number of water quality meters. Even if some turbidity and fine particles in the raw water are mixed in the filtered water due to membrane damage, the small amount of mixed turbidity and fine particles will be diluted by the total amount of filtered water before reaching the water quality meter, It may not be possible to accurately determine membrane damage. Therefore, when the turbidity supply device is installed on the treated water side of the membrane module, sanitary harmless turbidity is added to the treated water, the detection turbidity of the membrane damage is set high, and the raw water quality is clear A method has also been proposed in which film damage can be detected (see Patent Document 3).

JP 2000-279769 A JP 2003-1112018 A JP-A-6-320157

  By the way, in patent document 1, the membrane damage which detects the presence or absence of membrane damage by detecting the flow velocity of air or the flow rate of filtrate discharged from the membrane module when air is sent to the membrane module at a constant pressure. A detection method and a membrane damage detection method are described in which the application of pressure is stopped after air is sent out to the membrane module to a predetermined pressure, and the membrane damage is detected based on the pressure drop rate. However, when the membrane damage detection method described in Patent Document 1 is used, it is necessary to stop the membrane filtration device for membrane damage detection and to discharge at least one of the water on the treated water side or the filtrate water side of the membrane once. Therefore, there is a problem in that the operation rate of the membrane filtration device is lowered and a time during which water cannot be generated is generated, and continuous monitoring for membrane damage cannot be performed.

  In Patent Document 2, pressurized water in which air is dissolved is supplied to the raw water side to generate fine bubbles. When the membrane is damaged, the fine bubbles are mixed into the filtered water. Describes a film damage detection method for detecting the presence or absence of film damage by detecting fine bubbles mixed in the film. However, when the film damage detection method described in Patent Document 2 is used, it is necessary to further include equipment for producing pressurized water, and there is a problem that the apparatus configuration becomes complicated.

  Furthermore, in Patent Document 3, in order to prevent erroneous detection of membrane damage even when bubbles are mixed in the filtered water, turbid substances such as kaolin and diatomaceous earth that are harmless on hygiene are added to the water to be treated. A membrane damage detection method in which the turbidity of membrane damage is set high has been proposed. However, when the film damage detection method described in Patent Document 3 is used, there is a problem that it is necessary to further include a turbidity supply device, and the device configuration becomes complicated. Further, when the method for detecting film damage described in Patent Document 3 is used, there is a problem that the supplied turbidity itself does not peel off while adhering to the surface of the film, causing clogging of the film and causing an increase in the film differential pressure. there were.

  The present invention has been made in view of the above-described drawbacks of the prior art, and even when the raw water quality is clear, it is possible to continuously detect membrane damage without adding a new configuration. An object is to provide a membrane damage detection method and a membrane filtration device.

In order to solve the above-mentioned problems and achieve the object, a membrane damage detection method according to the present invention is a membrane damage detection method for detecting membrane damage of a membrane filtration device for filtering water to be treated. In order to increase the turbidity or the number of fine particles on the water side, the filtered water flows backward from the filtered water side to the treated water side with respect to the membrane, and the deposit on the treated water side surface of the membrane is temporarily removed from the membrane. Membrane damage detection reverse flow step to be peeled, Membrane damage detection filtration step of filtering treated water with increased turbidity or number of fine particles using the membrane after the membrane damage detection reverse flow step, and the membrane A water quality measurement step for measuring the quality of the filtered water filtered by the filtration step for damage detection, and a membrane damage judgment step for judging the presence or absence of membrane damage based on the water quality measured by the water quality measurement step, Reflux time in wound detecting reflux step is characterized by shorter than reflux time in the backwash process of discharging by stripping the deposits deposited on the treated water side surface of the membrane.

In the film damage detection method according to the present invention, the film damage determination step determines that the film is damaged when the water quality measured by the water quality measurement step rises above a predetermined reference value. And determining that the film is not damaged when the water quality measured by the water quality measurement step does not exceed the predetermined reference value .

The film damage detection method according to the present invention further includes a warning output step of outputting a warning notifying that the film is damaged when the film damage determination step determines that the film is damaged. It is further characterized by including .

The membrane filtration device according to the present invention is a membrane filtration device for filtering water to be treated. In order to increase the turbidity or the number of fine particles on the water to be treated side of the membrane, The turbidity or the number of fine particles increased due to the backflow means for backflowing from the side to the treated water side and temporarily separating the deposit on the treated water side surface of the membrane from the film, and the backflow of filtered water by the backflow means. Water quality measuring means for measuring the quality of filtered water to be treated, and membrane damage detecting means for judging the presence or absence of membrane damage based on the water quality measured by the water quality measuring means, wherein the backflow means is the membrane When the deposit on the treated water side surface of the film is temporarily peeled from the film to increase the turbidity or the number of fine particles on the treated water side of the film, the deposition deposited on the treated water side surface of the film For backwashing treatment that peels and discharges objects And performing kick back flow process with shorter processing times than reflux time.

In the membrane filtration device according to the present invention, the membrane damage detection means determines that the membrane is damaged when the water quality measured by the water quality measurement means rises above a predetermined reference value. When the water quality measured by the water quality measuring means does not exceed the predetermined reference value, it is determined that the membrane is not damaged .

The membrane filtration device according to the present invention further includes an output means for outputting a warning for notifying that the membrane is damaged when the membrane damage detecting means determines that the membrane is damaged. characterized in that was.

  According to the present invention, the sediment deposited on the surface of the membrane to be treated by filtration is temporarily peeled from the membrane using the backflow water, thereby increasing the turbidity or the number of fine particles on the surface of the membrane to be treated. Later, in order to detect the presence or absence of membrane damage by performing filtration treatment and measuring the quality of filtered water by the filtration treatment, the raw water quality is clarified by increasing the turbidity and the number of fine particles on the treated water side of the membrane. Even in such a case, accurate and continuous film damage detection can be performed without adding a new configuration.

  Embodiments of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the embodiments. In the description of the drawings, the same parts are denoted by the same reference numerals.

  Drawing 1 is a mimetic diagram showing composition of a membrane filtration device concerning an embodiment. As shown in FIG. 1, the membrane filtration apparatus 1 according to the embodiment includes a raw water tank 2, a raw water pump 3, a membrane inlet valve 4, a membrane module 5, a membrane outlet valve 6, a tank inlet valve 7, a water quality meter 9, and a reverse A membrane filtration mechanism 1 a having a washing tank 10, a backwash pump 11, a backwash valve 12 and a backwash drain valve 13, a control unit 20, an input unit 22, and an output unit 23 are provided.

  The raw water tank 2 is supplied with raw water such as surface water such as river water and lake water, and raw water such as groundwater, and stores the supplied raw water. The raw water pump 3 sends the raw water in the raw water tank 2 from the raw water tank 2 to the membrane module 5 under the control of the control unit 20. The membrane inlet valve 4 regulates the inflow of raw water from the raw water tank 2 to the membrane module 5.

  The membrane module 5 accommodates in the container a membrane in which micropores capable of removing inclusions such as turbidity and fine particles from raw water are contained, and performs a filtration process to remove the inclusions from the raw water sent from the raw water tank 2. The filtered water is sent to the backwash tank 10. In order to remove protozoa such as Cryptosporidium mixed in the raw water, micropores of a size that can remove turbidity components and fine particle components smaller than the size of the protozoa such as Cryptosporidium are formed in this membrane.

  The membrane outlet valve 6 regulates the flow of filtrate from the membrane module 5, and the tank inlet valve 7 regulates the inflow of filtrate from the membrane module 5 to the water quality meter 9 and the backwash tank 10. The water quality meter 9 measures the quality of the filtered water by measuring the turbidity or the number of fine particles of the filtered water sent from the membrane module 5. The water quality meter 9 always measures the quality of filtered water while the membrane filtration device is operating under the control of the control unit 20. The water quality meter 9 is constituted by a highly sensitive turbid clock or the like. The backwash tank 10 stores the predetermined amount of filtered water sent by the membrane module 5 and then sends filtered water.

  The backwash pump 10 peels and discharges deposits deposited on the surface of the membrane to be treated in the membrane module 5, that is, the primary surface that is the raw water side surface, under the control of the control unit 20. In order to carry out, the filtered water in the backwash tank 10 is sent from the backwash tank 10 to the membrane module 5. The backwash valve 12 adjusts the inflow of filtered water from the backwash tank 10 to the membrane module 5 in the backwash process under the control of the control unit 20. The backwash drain valve 13 is provided on a pipe connected to the raw water side region of the membrane module 5 and adjusts the discharge of deposits peeled off from the membrane surface by the backwash treatment.

  The control unit 20 controls each constituent part constituting the membrane filtration device 1. The control unit 20 detects the presence or absence of membrane damage in the membrane module 5. The control unit 20 is connected to an input unit 22 that inputs information necessary for filtration processing in the membrane filtration device 1 such as a processing instruction of the membrane filtration device 1 and an output unit 23 that outputs information about the filtration processing and a warning in the filtration processing. .

  Here, FIG. 2 and FIG. 3 show the actual structure of the membrane module 5 shown in FIG. FIG. 2 is a view showing the structure of the membrane module 5 shown in FIG. 1, and FIG. 3 is a view showing the main part of FIG. As shown in FIG. 2, the membrane module 5 has, for example, a hollow fiber membrane 51 as a membrane. As shown in FIG. 2, the raw water actually flows into the membrane module 5 through the membrane inlet tanks 4a and 4b, and the membrane permeated water that has permeated through the hollow fiber membrane 51 passes through the membrane outlet valves 6a and 6b. Into the backwash tank 10. Further, the backwash drainage is discharged through backwash drain valves 13a and 13b.

  And in the filtration process which filters raw | natural water, as shown in FIG.2 and FIG.3, the control part 20 makes the membrane inlet valve 4a, 4b, the membrane outlet valve 6a, 6b, and the tank inlet valve 7 open, and is a raw | natural water pump 3 is activated. Further, valves other than the membrane inlet valves 4a and 4b, the membrane outlet valves 6a and 6b, and the tank inlet valve 7, such as the backwash drainage valves 13a and 13b shown in FIG. 2, are closed. As a result, the raw water in the raw water tank 2 is sent to the membrane module 5 via the membrane inlet valves 4a and 4b. Specifically, as shown in FIGS. 2 and 3, raw water comes out of the hollow fiber membrane 51 in the membrane module 5. The hollow fiber membrane 51 is permeable to water but not air. The turbidity in the raw water is captured on the inner surface of the hollow fiber membrane 51, and the filtrate filtered in the hollow fiber membrane 51 of the membrane module 5 is collected in the water collection pipe 52, and then the membrane outlet valve 6 and the tank inlet valve 7. And then flows into the backwash tank 10. This filtered water is stored in the backwash tank 10 until it reaches a predetermined amount, and then supplied to the outside of the membrane filtration device 1. The filtered water filtered by the membrane module 5 is constantly monitored by a water quality meter 9.

  Moreover, the membrane filtration apparatus 1 performs the backwash process which peels and discharge | emits the deposit deposited on the raw | natural water side surface of the film | membrane in the membrane module 5 after performing the filtration process for predetermined time. In this backwash process, the control unit 20 opens the backwash valve 12, the membrane outlet valves 6a and 6b, and the backwash drain valves 13a and 13b, and starts the backwash pump 11. The valves other than the backwash valve 12, the membrane outlet valve 6, and the backwash drain valves 13a and 13b are in a closed state. As a result, the filtrate in the backwash tank 10 is sent to the membrane module 5 via the backwash valve 12 and the membrane outlet valves 6a and 6b in a flow reverse to the filtration process. Here, since the backwash pump 11 is driven so that the flow rate during the backwash process is 2 to 3 times the flow rate during the filtration process, the filtered water flows backward with a strong momentum with respect to the membrane in the membrane module 5. . As a result, the deposit deposited on the raw water side surface of the membrane in the membrane module 5 is separated by the backflow of the filtered water, and the deposit separated from the raw water side surface of the membrane is backwashed drainage from the backwash drainage valve 13. Is discharged out of the membrane filtration device 1.

  By the way, when an abnormality such as a membrane damage occurs during the filtration process, the raw water flows into the filtered water side from the damaged portion, so that the water quality deteriorates due to the mixing of the raw water. For this reason, when the measured value of the water quality meter 9 rises above a preset reference value, it is necessary to determine that the membrane has been damaged and take measures such as an emergency stop. However, when the raw water has a clear water quality such as groundwater or is controlled by a small number of water quality meters, membrane damage occurs and some turbidity and fine particles in the raw water are mixed from the damaged part. Even if it is, the small amount of mixed turbidity and fine particles will be diluted to a turbidity lower than the predetermined reference value by the total amount of filtered water before reaching the water quality meter. There was a case that could not be.

  For this reason, in the membrane filtration apparatus 1 concerning this Embodiment, the deposit deposited on the raw | natural water side surface of the film | membrane by filtration is temporarily peeled from a film | membrane using a backflow water, and the turbidity of the raw | natural water side of a film | membrane Alternatively, after increasing the number of fine particles, filtration treatment for membrane damage detection is performed, and the quality of filtrate water by the filtration treatment for membrane detection is measured to detect the presence or absence of membrane damage. That is, the membrane filtration apparatus 1 increases the turbidity and the number of fine particles on the raw water side of the membrane, and performs filtration treatment for membrane damage detection and measurement of the quality of filtered water. In other words, the membrane filtration device 1 increases the turbid mass and the number of fine particles mixed in the filtered water from the damaged portion of the membrane to a certain extent that the abnormality can be sufficiently detected by the water quality meter 9 to improve the accuracy of the membrane damage detection. Yes.

  Specifically, each process performed for film damage detection will be described. As shown in FIGS. 4 to 6, in this membrane damage detection, first, the control unit 20 performs the backwash valve 12, the membrane outlet valves 6a and 6b, and the backwash drain valve in the same manner as the backwash process described above. The backwash pump 11 is started after the membrane inlet valves 4a and 4b are closed while the valves 13a and 13b are opened. As a result, the filtered water in the backwash tank 10 flows back to the membrane module 5 as indicated by an arrow Y11 in FIG. As shown by the arrows in FIGS. 5 and 6, due to the backflow of the filtrate water (membrane permeate) from the filtrate side of the membrane module 5, that is, the secondary side, the raw water side surface of the hollow fiber membrane 51 of the membrane module 5 The deposited deposit A peels off. Next, immediately after the deposit deposited on the raw water side surface of the membrane of the membrane module 5 is separated from the membrane surface, the backwash pump 11 is stopped, the backwash valve 12, the membrane outlet valves 6a and 6b, and the backwash drain valve 13a and 13b are closed to create a state in which the suspended turbidity is retained in the system. By this operation, as shown in FIG. 6, the deposit A peeled off from the surface of the hollow fiber membrane 51 is dispersed in the raw water side of the membrane module 5, that is, in the water of the raw water side region S1, and in the raw water side region S1 Increased turbidity or fine particle count.

  And in the membrane filtration apparatus 1, the same operation as the filtration process mentioned above is performed, and the filtration process for a membrane damage detection is performed. That is, the control unit 20 opens the membrane inlet valves 4a and 4b, the membrane outlet valves 6a and 6b, and the tank inlet valve 7, starts the raw water pump 3, and as shown in FIG. The membrane 51 is subjected to filtration treatment, and the filtered water delivered from the membrane module 5 is poured into the backwash tank 10 via the membrane outlet valve 6 and the tank inlet valve 7. As a result, the water to be treated in the raw water side region S1 in which the turbidity or the number of fine particles is increased is filtered by the membrane in the membrane module 5.

  If the hollow fiber membrane 51 in the membrane module 5 is not damaged, even if it is subjected to a delivery process by the raw water pump 3, a large amount of turbidity and fine particles in the raw water side region S1 are mixed into the filtered water. It is blocked by the hollow fiber membrane 51. Therefore, the filtered water delivered from the membrane module 5 maintains the required water quality, and the measured turbidity of the filtered water by the water quality meter 9 is also below a preset reference value.

  On the other hand, when the hollow fiber membrane 51 in the membrane module 5 is damaged, a large amount of turbidity or fine particles in the raw water-side region S1 is subjected to the sending process by the raw water pump 3, and the arrow 15 in FIG. As shown in FIG. 2, the water is mixed directly into the filtrate from the hollow fiber membrane 51 through the damaged portion of the hollow fiber membrane 51 and is sent out of the membrane module 5 from the water collecting pipe 52. Therefore, the filtered water delivered from the membrane module 5 as indicated by the arrow Y16 is mixed with a large amount of turbidity or fine particles and the water quality is deteriorated. The turbidity measurement value of the filtered water by the water quality meter 9 is set in advance. It will rise above the reference value. The control unit 20 can accurately detect that the membrane of the membrane module 5 is damaged from the measured turbidity of the filtered water by the raised water quality meter.

  Thus, in the membrane filtration device 1, even if the raw water quality is clear, the membrane is used to the extent that the water quality meter 9 can sufficiently detect an abnormality using the conventional backwashing mechanism for performing the backwashing process as it is. The accuracy of membrane damage detection is increased by increasing the turbidity and the number of fine particles in the raw water side region.

  Next, the filtration process and the membrane damage detection process in the membrane filtration device 1 will be described with reference to FIG. First, after the start of the filtration process by the membrane filtration apparatus 1 is instructed, as shown in FIG. 8, the control unit 20 initializes the number of times n of the filtration process for filtering the raw water, and sets n = 1 (step S2). ). Then, the control unit 20 opens the membrane inlet valve 4, the membrane outlet valve 6 and the tank inlet valve 7, activates the raw water pump 3, and performs a filtration process for filtering the raw water in the raw water tank 2 through the membrane module 5. Perform (step S4). The membrane filtration device 1 uses, for example, a membrane having the properties shown in Table T1 in FIG. 9 to filter the raw water having the quality shown in Table T1. And the membrane filtration apparatus 1 performs the filtration process in step S4 on the filtration process conditions illustrated to table | surface T1. During the filtration process in step S <b> 4, the water quality meter 9 continuously measures the quality of the filtered water and outputs the measured value to the control unit 20.

  Next, the control unit 20 determines whether or not a predetermined filtration time has elapsed after starting the filtration process (step S6). When it is determined that the predetermined filtration time has not elapsed since the start of the filtration process (step S6: No), the control unit 20 returns to step S4 and continues the filtration process. On the other hand, when the control unit 20 determines that a predetermined filtration time has elapsed since the start of the filtration process (step S6: Yes), the backwash valve 12, the membrane outlet valve 6, and the backwash drainage The valve 13 is opened, the backwash pump 11 is started, and backwashing treatment is performed to peel and discharge the deposits deposited on the surface of the membrane to be treated in the membrane module 5 (step S8). In addition, the membrane filtration apparatus 1 performs the backwash process in step S8 on the backwash process conditions illustrated in Table T1.

  Then, after the backwash process is completed, the control unit 20 compares the number n of the filtration processes with a predetermined maximum number N, and determines whether n = N (step S10). The number of executions n does not exceed the maximum number of executions N, and n ≦ N. This maximum number of times N is set based on the number of filtration treatments that can guarantee the quality of filtered water when using an undamaged membrane, the turbidity and number of fine water in the raw water, and the properties of the membrane. When the number n of treatments reaches this maximum number N, it is necessary to verify the presence or absence of membrane damage in the membrane module 5 in order to guarantee the quality of filtrate water in subsequent filtration treatments. When the control unit 20 determines that n = N is not satisfied (step S10: No), that is, when it is determined that n <N, the filtration processing execution number n has not reached the predetermined maximum number of executions N. After performing the filtration execution number n update process (step S12) for adding 1 to the execution number n and updating the execution number n, the process returns to step S4, and the filtration process and the backwash process are performed again.

  On the other hand, when the control unit 20 determines that n = N (step S10: Yes), in order to verify the presence or absence of membrane damage in the membrane module 5, the normal filtration process shown in step S4 is performed. The same treatment is performed to deposit deposits on the raw water side surface of the membrane. Thereafter, the control unit 20 performs a film damage detection process.

  First, the control unit 20 causes the membrane damage to temporarily separate the deposit on the raw water side surface of the membrane from the membrane by causing the filtered water to flow backward to the membrane in order to increase the turbidity or the number of fine particles on the raw water side of the membrane. A backflow process for detection is performed (step S14). In this membrane damage detection backflow process, the controller 20 opens the backwash valve 12, the membrane outlet valve 6, and the backwash drain valve 13 to start the backwash pump 11, and then stops the backwash pump 11. Then, the backwash valve 12, the membrane outlet valve 6, and the backwash drain valve 13 are closed. The purpose of this reverse flow treatment for membrane damage detection is to increase the turbidity or the number of fine particles in the membrane raw water side region of the membrane module 5. That is, the backflow time of the membrane damage detection backflow processing is sufficient if the deposit on the raw water side surface of the membrane in the membrane module 5 can be temporarily separated from the membrane. For this reason, the backflow time in the backflow process for film damage detection is shorter than the backflow time in the backwash process (step S8) described above. For example, as shown in Table T1, the backwash process in Step S8 requires a backflow time of 60 seconds in order to completely remove the deposit on the film surface and discharge it, whereas the table in FIG. As shown in T2, in the backflow process for film damage detection, it is sufficient if the deposit on the film surface can be temporarily peeled off. Even if a reverse flow treatment is newly added to increase the turbidity and the number of fine particles in the raw water side region of the membrane to detect membrane damage, the reverse flow treatment time itself is sufficient, so membrane damage detection The total processing time for can be implemented in a relatively short time. In addition, the backflow process for membrane damage detection is actually performed at each backflow time, and the turbidity and the number of fine particles in the raw water side region of the membrane are measured for each backflow time. Then, based on the distance between the membrane module 5 and the water quality meter 9 and the like, the turbidity and the number of fine particles that the water quality meter 9 can measure anomalies are set. The corresponding backflow time may be selected as the backflow time in this membrane damage detection backflow process.

  Next, the control unit 20 uses the membrane to filter the water to be treated whose turbidity or number of fine particles has been increased in the membrane damage detection backflow processing after the membrane damage detection backflow processing is completed. Filtration is performed (step S16). In this membrane damage detection filtration process, the control unit 20 opens the membrane inlet valve 4, the membrane outlet valve 6 and the tank inlet valve 7, activates the raw water pump 3, and increases the turbidity and the number of fine particles. The raw water in the raw water side region is filtered through the membrane in the membrane module 5. And the control part 20 performs the water quality measurement process which makes the water quality meter 9 measure the quality of the filtrate filtered by the membrane damage detection filtration process with the membrane damage detection filtration process (step S18). The water quality meter 9 measures the quality of the filtrate of the water to be treated whose turbidity or the number of fine particles has increased due to the backflow of the filtrate in the membrane damage detection filtration process. In this membrane damage detection filtration process, it is sufficient to obtain the quality of the filtered water of the raw water side region with increased turbidity and the number of fine particles, so the filtration time of the membrane damage detection filtration process is: A time shorter than the filtration time in the filtration process (step S4) described above is sufficient. For example, as shown in Table T1, in the filtration process in Step S4, the filtration time is 60 minutes, whereas as shown in Table T2 of FIG. 10, the filtration time in the membrane damage detection filtration process is 10 minutes. . The filtration time of the membrane damage detection filtration process is set based on the distance between the membrane module 5 and the water quality meter 9 so that the water quality meter 9 can measure the abnormality.

  And the control part 20 judges whether the measured value by the water quality meter 9 rose exceeding a predetermined reference value (step S20). When the control unit 20 determines that the measured value by the water quality meter 9 has increased beyond a predetermined reference value (step S20: Yes), the control unit 20 determines that the membrane of the membrane module 5 is damaged (step S22). . Next, the output unit 23 outputs a warning notifying that the membrane of the membrane module 5 is damaged under the control of the control unit 20 (step S24). By checking this warning, the administrator of the membrane filtration device 1 can recognize that the membrane of the membrane module 5 has been damaged, and can quickly deal with the membrane damage.

  On the other hand, when the control unit 20 determines that the measured value by the water quality meter 9 does not increase and does not exceed the predetermined reference value (step S20: No), the membrane of the membrane module 5 is not damaged. Judgment is made (step S26). Next, the control unit 20 determines whether or not the continuation of the filtration process is instructed (step S28). If it is determined that the continuation of the filtration process is instructed (step S28: Yes), step S2 is performed. Returning to FIG. 2, after the number of times n of the filtration process is initialized, the filtration process and the backwash process are performed. On the other hand, the control part 20 complete | finishes the filtration process in the membrane filtration apparatus 1, when it is judged that the continuation of the filtration process is not instruct | indicated (step S28: No). As shown in FIG. 8, in the membrane filtration apparatus 1, a normal filtration process for filtering raw water and a backwash process for discharging deposits deposited on the raw water side surface of the membrane of the membrane module 5 are continued as they are. Thus, backwashing processing for detecting membrane damage, filtration processing for detecting membrane damage, and water quality measurement processing can be performed.

  As described above, in the membrane filtration device 1 according to the present embodiment, the deposit deposited on the surface of the membrane to be treated by filtration is temporarily peeled from the membrane using the backflow water, and the membrane is treated. The water side turbidity or fine particle count is increased. That is, the membrane filtration apparatus 1 according to the present embodiment uses the backwashing mechanism that performs the backwashing process without adding a new configuration as it is, and can sufficiently detect the abnormality by the water quality meter 9 to some extent. Since the turbidity and the number of fine particles are increased in the treated water side region, the raw water quality is clear and the turbidity and fine particles mixed in the filtered water due to membrane damage are diluted by the entire filtered water. Even if it exists, the precision of a film | membrane damage detection can be raised and an exact film | membrane damage detection can be performed. Actually, in the membrane filtration apparatus 1 according to the present embodiment, as a result of raising the turbidity and the number of fine particles in the region to be treated of the membrane, as shown in FIG. Since a clear difference occurs in the fine particle concentration measured by 9, film damage can be detected sufficiently accurately.

  Moreover, according to the membrane filtration apparatus 1, the deposit deposited on the surface of the membrane to be treated by filtration is temporarily peeled off from the membrane using the backflow water, and the membrane to be treated side of the membrane for membrane damage detection. Because the turbidity or the number of fine particles is increased, the normal filtration process that filters raw water and the backwash process that discharges the sediment deposited on the raw water side surface of the film are continuously detected for film damage detection. Membrane washing back washing treatment, membrane damage detection filtration treatment and water quality measurement treatment can be performed. Therefore, according to the membrane filtration device 1, it is not necessary to stop the fresh water treatment of the membrane filtration device 1 for membrane damage detection, and each treatment for membrane detection is performed continuously from the normal filtration treatment. Therefore, damage to the membrane of the membrane filtration device can be detected continuously.

  Moreover, the membrane filtration apparatus 1 increases the turbidity and the number of fine particles in the region to be treated of the membrane by using the deposit deposited on the surface of the membrane to be treated by filtration as it is. That is, in the membrane filtration device 1, the suspended matter and fine particles increased in the treated water side region of the membrane are components originally contained in the raw water. Therefore, in the membrane filtration apparatus 1, it is not necessary to add new turbidity. For this reason, according to the membrane filtration apparatus 1, it is not necessary to provide the turbidity supply apparatus for raising the turbidity of the to-be-processed water side area | region and fine particle count which were required conventionally. Further, in the membrane filtration device 1, the suspended matter and fine particles increased in the region to be treated of the membrane are peeled off by the backflow treatment in a shorter time than the backflow time in the backwash treatment. It can be sufficiently peeled off from the film during processing. For this reason, turbidity and fine particles increased in the treated water side region of the membrane for detecting membrane damage in the membrane filtration device 1 do not cause clogging of the membrane. Therefore, in the membrane filtration apparatus 1, the membrane damage detection process can be performed under a normal membrane differential pressure, and the membrane damage can be accurately detected.

  Furthermore, in this embodiment, even if the turbidity and fine particles mixed in the filtered water due to membrane damage are diluted to the water quality meter by the whole raw water filtered water, the water quality meter 9 The water quality of the filtered water is measured after increasing the turbidity and the number of fine particles in the treated water side region of the membrane to a certain extent that an abnormality can be sufficiently detected. That is, in this embodiment, when the membrane is damaged, the turbidity and the number of fine particles mixed in the filtered water from the membrane damaged portion in the membrane damage detection filtration process are filtered from the membrane damaged portion as it is. The filtration water for membrane damage detection filtration treatment can reach a water quality meter for membrane damage detection while maintaining a much larger number of turbidity and fine particles, compared with the case where it is mixed with water. Even when the module is monitored with a small number of water quality meters, it is not necessary to increase the number of water quality meters to detect membrane damage. For example, as shown in the filtration mechanism 101a in FIG. 12, the membrane damage of six membrane modules 5 is detected by one water quality meter 9, and one of the six membrane modules 5 is detected. A case where there is a film damage will be described as an example. The number of fine particles in the filtered water sent from the membrane module 5 having this membrane damage is reduced to 1/6 by the filtered water of the other five membrane modules 5 before reaching the water quality meter 9, but the other In consideration of dilution by the membrane module 5, the turbidity and the number of fine particles in the treated water side region of the membrane module 5 are sufficiently raised. Therefore, according to the present embodiment, membrane damage detection can be performed sufficiently accurately without increasing the number of water quality meters for membrane damage detection.

  In the flow chart shown in FIG. 8, the case where each process for membrane damage detection such as the backflow process for membrane damage detection and the membrane damage filtration process is performed after the filtration process and the backwash process of a predetermined number of times are shown. Of course, but not limited to this. For example, the membrane filtration device 1 may periodically perform processes for detecting membrane damage. When instruction information for instructing detection of membrane damage is input by the input unit 22, the processes for detecting membrane damage are performed. You may do it.

  Further, in the present embodiment, the case where the backflow water is used as the backflow process for detecting the membrane damage has been described as an example. However, the reverse pressure air is used instead of the backflow water, and the raw water side of the membrane in the membrane module 5 is used. After the surface deposit is temporarily peeled off from the film, the film damage may be detected by performing filtration treatment for film damage detection.

  Specifically, the membrane filtration device 1 allows pressurized air to flow from either the raw water side channel or the membrane permeate water side channel with respect to the membrane. In the case of flowing air from the raw water side flow path, for example, an air supply mechanism for supplying air is provided between the membrane inlet valve 4 and the membrane module 5, and the air is supplied from the air supply mechanism under the control of the control unit 20. The turbidity deposited on the surface of the film can be removed. And when air is poured from the raw water side flow path, the suspended matter deposited on the membrane surface can be removed by vibration due to air inflow. In the case of flowing air from the membrane permeated water side flow path, for example, an air supply mechanism for supplying air is provided between the membrane outlet valve 6 and the membrane module 5, and this air supply mechanism is controlled under the control of the control unit 20. By allowing air to flow from the turbidity, the turbidity deposited on the film surface can be separated by vibration. In this way, by flowing air from either the raw water side flow path or the membrane permeate water side flow path, the deposit on the treated water side surface of the film is temporarily peeled off from the film, and the film damage is detected. Filtration treatment may be performed to detect membrane damage. In this case, since damage to the membrane can be detected before the raw water is actually filtered, it is possible to reliably avoid the supply of filtered water filtered by the damaged membrane. In the present embodiment, the case where the film structure is a horizontal type has been described as an example in FIGS. 3 and 5 to 7. However, the present invention is not limited to this, and the present invention can also be applied to a case where the film structure is a vertical type.

It is a schematic diagram which shows the structure of the membrane filtration apparatus concerning embodiment. It is a figure which shows the structure of the membrane module shown in FIG. It is a figure which shows the principal part of FIG. It is a figure explaining the backflow process for a membrane damage detection in the membrane filtration apparatus shown in FIG. It is a figure explaining the backflow process for a membrane damage detection in the membrane filtration apparatus shown in FIG. It is a figure explaining the backflow process for a membrane damage detection in the membrane filtration apparatus shown in FIG. It is a figure explaining the filtration process for membrane damage detection in the membrane filtration apparatus shown in FIG. It is a flowchart which shows the process sequence of the filtration process and membrane damage detection process in the membrane filtration apparatus shown in FIG. It is the figure which showed the table | surface which illustrates the property of the film | membrane of the membrane module shown in FIG. 1, and the filtration process conditions and backwash process conditions shown in FIG. It is the figure which showed the table | surface which illustrates the conditions of the backflow process for film | membrane damage detection shown in FIG. 8, and the filtration process for film | membrane damage detection. It is a figure which shows the measurement result of the number of microparticles | fine-particles by the water quality meter of the membrane filtration apparatus in this Embodiment. It is a figure which shows the other structure of the filtration mechanism shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Membrane filtration apparatus 1a Membrane filtration mechanism 2 Raw water tank 3 Raw water pump 4 Membrane inlet valve 5 Membrane module 6 Membrane outlet valve 7 Tank inlet valve 9 Water quality meter 10 Backwash tank 11 Backwash pump 12 Backwash valve 13 Backwash drainage valve 20 Control unit 22 Input unit 23 Output unit

Claims (6)

In a membrane damage detection method for detecting membrane damage of a membrane filtration device for filtering water to be treated,
In order to increase the turbidity or the number of fine particles on the treated water side of the membrane, the filtered water flows backward from the filtered water side to the treated water side with respect to the membrane, and the deposit on the treated water side surface of the membrane is A backflow step for detecting membrane damage that temporarily peels off the membrane;
After the membrane damage detection reverse flow step, the membrane damage detection filtration step of filtering the treated water with increased turbidity or the number of fine particles using the membrane;
A water quality measurement step for measuring the quality of the filtered water filtered by the membrane damage detection filtration step;
A film damage judging step for judging the presence or absence of film damage based on the water quality measured by the water quality measuring step ,
The film damage detection method according to claim 1, wherein the backflow time in the backflow step for film damage detection is shorter than the backflow time in the backwash process in which deposits deposited on the surface of the film to be treated are peeled off and discharged. The film damage determination step determines that the film is damaged when the water quality measured by the water quality measurement step exceeds a predetermined reference value, and the water quality measured by the water quality measurement step is The film damage detection method according to claim 1, wherein if the predetermined reference value is not exceeded, it is determined that the film is not damaged. A warning output step of outputting a warning notifying that the film is damaged when it is determined that the film is damaged in the film damage determination step.
The film damage detection method according to claim 1, further comprising: In a membrane filtration device for filtering the water to be treated,
In order to increase the turbidity or the number of fine particles on the treated water side of the membrane, the filtered water flows backward from the filtered water side to the treated water side with respect to the membrane, and the deposit on the treated water side surface of the membrane is Backflow means for temporarily peeling from the membrane;
Water quality measuring means for measuring the quality of filtered water of treated water whose turbidity or number of fine particles has increased due to the backflow of filtered water by the backflow means;
And a membrane damage detection means for determining the presence or absence of membrane damage based on the quality measured by the quality measuring means,
In the case where the deposit on the treated water side surface of the film is temporarily peeled off from the film in order to increase the turbidity or the number of fine particles on the treated water side of the film, A membrane filtration device, wherein the backflow treatment is performed in a shorter processing time than the backflow time in the backwashing treatment in which deposits deposited on the water side surface are peeled off and discharged. The membrane damage detection means determines that the membrane is damaged when the water quality measured by the water quality measurement means rises above a predetermined reference value, and the water quality measured by the water quality measurement means The membrane filtration device according to claim 4, wherein if the predetermined reference value is not exceeded, it is determined that the membrane is not damaged. When the film damage detection means determines that the film is damaged, the output means outputs a warning notifying that the film is damaged
The membrane filtration device according to claim 4 or 5, further comprising:

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