JP2011031145A - Filter member-washing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter member-washing system which subjects a filter member to back washing with effective timing. <P>SOLUTION: The filter member-washing system includes: a filtration processing device 2 having a filter member 23 which conducts the filtration of treatment-object water W1; a treatment-object water pouring means 42 which pours the treatment-object water W1 from the primary side area 21 toward the secondary side area 22; a washing liquid-feeding means 62 which feeds a washing liquid W3 to the filter member 23 from the secondary side toward the primary side; a pressure difference-measuring means 3 which measures a difference in pressure between the primary side area 21 and the secondary side area 22; a determination means 81 which determines whether the washing liquid-feeding means 62 starts up on the basis of a set threshold value; and a control means 83 which controls the start-up of the washing liquid-feeding means 62 on the basis of the result of the determination made by the determination means 81. After the washing liquid-feeding means 62 finishes the feeding of the washing liquid W3, the determination means 81 resets the threshold value to a value obtained by adding a prescribed offset value to a posterior-to-washing pressure difference value computed on the basis of a measured pressure difference value which is a pressure difference measured by the pressure difference-measuring means 3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a filtration member cleaning system for cleaning a filtration member such as a filtration membrane module in a filtration apparatus that constitutes a water treatment system.

Conventionally, water treatment that produces high-purity treated water (purified water) from treated water (raw water) such as factory wastewater and domestic wastewater, and makes the treated water usable for various process water, intermediate water, miscellaneous water, etc. The system is known. In the water treatment system, for example, a filtration treatment by a filtration treatment device is performed on the water to be treated.
The filtration apparatus includes, for example, a filtration membrane module that filters the water to be treated by passing the water to be treated from the primary side to the secondary side as a filtration member. According to the filtration apparatus, the water to be treated can be filtered by allowing the water to be treated to pass through the filtration membrane module from the primary side to the secondary side.

  In the filtration apparatus, when the filtration process is repeated, the filtration membrane module is blocked by impurities such as suspended substances trapped in the filtration membrane module. Therefore, it is necessary to perform reverse cleaning on the closed membrane filter module to remove impurities attached to the membrane filter module (see, for example, Patent Document 1 below). In the reverse cleaning, water or a cleaning liquid is supplied to the filtration membrane module from the secondary side to the primary side to wash the filtration membrane module. Backwashing is often performed regularly (for example, every other month or at a predetermined flow rate for each process).

Japanese Patent Laid-Open No. 2000-300969

  However, when the membrane filter module is significantly contaminated, for example, when the water to be treated having a high degree of contamination is introduced into the filtration apparatus, the membrane filter module is blocked before periodic backwashing is performed. There is a case. When the use of the filtration apparatus is continued in a state where the filtration membrane module is blocked, there arises a problem that a predetermined filtration performance cannot be exhibited. In addition, in the filtration membrane module that has been used in a closed state, impurities attached to the filtration membrane module cannot be removed even if reverse washing or immersion washing is performed later, which may shorten the life of the filtration membrane module. .

In addition, as another technique to prevent clogging of the filtration membrane module, the flow rate of the permeated water on the secondary side of the filtration membrane module is monitored, and when the flow rate of the permeated water decreases, the adhesion of impurities to the filtration membrane module is detected. A way to do this is conceivable.
However, in the method of monitoring the flow rate of the permeated water, for example, if the discharge force of the pump provided on the primary side or the secondary side of the membrane filter module is increased, the flow rate of the permeated water increases. Cannot detect a drop in In addition, if the discharge force of the pump is increased, impurities attached to the filtration membrane module cannot be removed even if reverse cleaning or immersion cleaning is performed later, which may shorten the life of the filtration membrane module. Therefore, the method of monitoring the flow rate of the permeated water is not perfect as a technique for preventing the filtration membrane module from being blocked.
The above-mentioned problem is the same in both cases of the external pressure filtration processing apparatus in which a pressure pump is installed on the primary side of the filtration member and the immersion type filtration treatment apparatus in which a suction pump is installed on the secondary side of the filtration member. appear.

  Accordingly, an object of the present invention is to provide a filtration member cleaning system capable of performing reverse cleaning on a filtration member at an effective timing while suppressing occurrence of blockage with respect to the filtration member in the filtration apparatus. And

  The present invention has a filtration member that passes the treated water from the primary side toward the secondary side and filters the treated water, and a primary side region and a secondary side region that are partitioned by the filtering member. And a filtration device that performs filtration of the treated water by passing the treated water through the filtration member from the primary side region toward the secondary side region, and the secondary side from the primary side region. Water to be treated for circulating the water to be treated toward the side region, cleaning liquid supply means for supplying a cleaning liquid from the secondary side to the primary side to the filtration member, the primary region and the second side A pressure difference measuring means for measuring a pressure difference with the secondary region, a determination means capable of setting a predetermined threshold, and determining the activation of the cleaning liquid supply means based on the set threshold; and the determination means Based on the determination result by Control means for controlling the start-up of the supply means, and the determination means measures the threshold value as a pressure difference measured by the pressure difference measurement means after the supply of the cleaning liquid by the cleaning liquid supply means is completed. The present invention relates to a filtration member cleaning system that resets a value obtained by adding a predetermined offset value to a post-cleaning pressure difference value calculated based on a pressure difference value.

  Further, it is preferable that the determination unit resets the threshold value after the supply of the cleaning liquid by the cleaning liquid supply unit and during activation of the treated water circulation unit.

  Further, the pressure difference measuring means starts measuring the pressure difference after the supply of the cleaning liquid by the cleaning liquid supplying means and after starting the treated water circulation means, and the determining means The value is preferably calculated by averaging all or a part of the plurality of measured pressure difference values measured by the pressure difference measuring means.

  Further, it is preferable that the pressure difference measuring unit starts measuring the pressure difference after a predetermined time has elapsed after the supply of the cleaning solution by the cleaning solution supplying unit.

  Moreover, it is preferable that the said control means starts the said washing | cleaning liquid supply means, when the said measured pressure difference value becomes more than the said threshold value.

  ADVANTAGE OF THE INVENTION According to this invention, the filtration member washing | cleaning system which can perform back washing | cleaning with respect to a filtration member at an effective timing can be provided, suppressing generation | occurrence | production of obstruction | occlusion with respect to the filtration member in a filtration processing apparatus. .

It is a lineblock diagram showing filtration member washing system 1 of one embodiment of the present invention. It is a figure which shows 1 cycle of an example of operation | movement of the filtration member washing | cleaning system shown in FIG. It is a flowchart which shows an example of operation | movement of the filtration member washing | cleaning system shown in FIG. It is a figure which shows the timing of the measurement of a pressure difference.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram illustrating a filtration member cleaning system 1 according to an embodiment of the present invention.
A filtration member cleaning system 1 of the present embodiment shown in FIG. 1 constitutes a part of a water treatment system. The water treatment system, for example, removes impurities such as suspended solids from the treated water (raw water) W1 such as factory wastewater and domestic wastewater, and can be reused as various process water, intermediate water, miscellaneous water, etc. Purified water) W2.

As shown in FIG. 1, the filtration member cleaning system 1 of the present embodiment includes a filtration treatment device 2 that performs a filtration treatment, a filtration pump 42 as treated water circulation means, and treated water in which treated water W2 is stored. The tank 5, the cleaning liquid tank 7 in which the cleaning liquid W3 is stored, the cleaning pump 62 as the cleaning liquid supply means, the pressure sensor 3 as the pressure difference measuring means, the determination unit 81 as the determination means, and the cleaning as the control means The system control device 8 having the control unit 83 is mainly configured.
Further, the filtration member cleaning system 1 of the present embodiment further includes a to-be-treated water line L1, a first treated water line (second washed liquid line) L2, a second treated water line L3, a first washed liquid line L4, and a treated water valve. 41, a treated water check valve 43, a cleaning liquid valve 61, a cleaning liquid check valve 63, and the like.

The water to be treated W1 is subjected to various water treatments (pre-filtration treatment) before the filtration treatment by the filtration treatment device 2, and then supplied to the filtration treatment device 2 via the treatment water line L1.
The treated water (permeated water) W2 filtered by the filtration device 2 is a first treated water line L2 and a second treated water line L3 (hereinafter, both treated lines L2 and L3 are collectively referred to as “treated water line L23”). And also conveyed to the treated water tank 5.

The cleaning liquid W3 stored in the cleaning liquid tank 7 is supplied to the filtration apparatus 2 via the first cleaning liquid line L4 and the second cleaning liquid line L2 (hereinafter, both lines L4 and L2 are also referred to as “cleaning liquid line L42”). Be transported.
In addition, the 1st process water line L2 and the 2nd washing | cleaning liquid line L2 are lines used together, and will say according to a usage condition.
Further, the “line” is a general term for a line through which an object such as a flow path, a route, and a pipe can flow.

Hereinafter, the filtration member cleaning system 1 of the present embodiment will be described in detail.
Various types of water treatment (pre-filtration treatment) are performed before the filtration treatment by the filtration treatment apparatus 2. As shown in FIG. 1, the to-be-processed water W1 in which the prefiltration process was performed is supplied to the filtration apparatus 2 via the to-be-processed water line L1.

The filtration apparatus 2 is an apparatus that performs a filtration process on the water to be treated W1. As shown in FIG. 1, the filtration apparatus 2 includes a filtration water tank 24 and a filtration membrane module 23 as a filtration member.
The filtration water tank 24 can store the water to be treated W1 and the filtration membrane module 23 therein. To-be-processed water W1 is supplied to the inside of the filtration-treated water tank 24 via the to-be-processed water line L1, and is stored.

The filtration membrane module 23 includes a large number of filtration membranes (not shown), and impurities such as suspended substances are removed by the filtration membrane.
Examples of the filtration membrane include an ultrafiltration membrane (UF membrane), a microfiltration membrane (MF membrane), a nanofiltration membrane (NF membrane), and a reverse osmosis membrane (RO membrane). Examples of the shape of the filtration membrane include a flat membrane type, a hollow fiber membrane type, a tubular type, and a Nomoris type. These filtration membranes are required for treated water, for example, for water supply to thermal equipment such as steam boilers, hot water boilers, cooling towers, and water heaters, and for cleaning semiconductor manufacturing, electronic components, medical equipment, etc. It is appropriately selected and used depending on the application.

  The filtration processing apparatus 2 in this embodiment performs a filtration process by a membrane separation activated sludge method (MBR; membrane bioreactor). In the case of MBR filtration, a hollow fiber membrane type UF membrane or MF membrane is usually used in a state where it is immersed in the filtration water tank 24.

The filtration apparatus 2 includes a primary side area 21 that is an area inside the filtration process water tank 24 and outside the filtration membrane module 23, and a secondary side area 22 that is an area inside the filtration membrane module 23. That is, the primary side region 21 and the secondary side region 22 are partitioned by the filtration membrane module 23.
The filtration membrane module 23 filters the water to be treated W1 by passing the water to be treated W1 from the primary side toward the secondary side. According to the filtration treatment apparatus 2, the treated water W1 is filtered by passing the treated water W1 from the primary side region 21 toward the secondary side region 22 through the filtration membrane module 23, thereby treating the treated water (permeation). Water) W2 can be obtained.
The filtration membrane module 23 is back-washed by supplying the cleaning liquid from the secondary side.

A treated water line L23 (first treated water line L2) is connected to the secondary region 22 of the filtration membrane module 23 of the filtration apparatus 2. The downstream end of the treated water line L23 (second treated water line L3) is connected to the treated water tank 5.
The treated water W2 obtained by filtering the treated water W1 is transported to the treated water tank 5 via the treated water line L23 and stored.

  The treated water tank 5 is a tank that stores treated water W2. The treated water tank 5 is connected to the downstream end of the treated water line L23 (second treated water line L3).

The treated water line L <b> 23 is a line that conveys the treated water W <b> 2 obtained by the filtration device 2 to the treated water tank 5.
The treated water line L23 includes a first treated water line L2, a first connection portion J1, and a second treated water line L3. The 1st treated water line L2 and the 2nd treated water line L3 are connected in the 1st connection part J1. The 1st treated water line L2 is a line which connects the secondary side area | region 22 of the filtration membrane module 23 of the filtration apparatus 2, and the 1st connection part J1. The second treated water line L3 is a line that connects the first connection portion J1 and the treated water tank 5.

  The filtration pump 42 is connected in the middle of the second treated water line L3. According to the filtration pump 42, the suction side force causes the secondary side region 22 of the filtration treatment device 2 to have a negative pressure via the treated water line L <b> 23 (the second treated water line L <b> 3 and the first treated water line L <b> 2). be able to. Therefore, the filtration pump 42 can distribute the treated water W <b> 1 from the primary side region 21 toward the secondary side region 22.

  The treated water valve 41 is provided between the first connection portion J1 and the filtration pump 42 in the second treated water line L3. According to the treated water valve 41, the second treated water line L3 can be opened and closed between the first connection portion J1 and the filtration pump.

  The treated water check valve 43 is provided between the filtration pump 42 and the end (second end) on the treated water tank 5 side in the second treated water line L3. The treated water check valve 43 is a valve that allows the fluid to flow only in the direction from the filtration pump 42 toward the second end of the second treated water line L3.

  The pressure sensor 3 is connected to the first treated water line L2 at the second connection portion J2. The pressure sensor 3 is a sensor that measures a pressure difference between the primary side region 21 and the secondary side region 22. More specifically, the pressure sensor 3 is a sensor that measures the pressure of the first treated water line L <b> 2 that has become negative due to the suction force of the filtration pump 42. Since the atmospheric pressure is acting on the primary side region 21 of the filtration processing device 2, the pressure sensor 3 measures the pressure of the first treated water line L2 and thereby the primary side region 21 and the secondary side region 21 of the filtration processing device 2 are measured. The transmembrane pressure difference between the secondary region 22 (the transmembrane pressure difference between the primary side and the secondary side across the filtration membrane module 23) can be measured.

  The cleaning liquid line L <b> 42 is a line that conveys the cleaning liquid W <b> 3 stored in the cleaning liquid tank 7 to the secondary region 22 of the filtration processing device 2. The cleaning liquid line L42 includes a first cleaning liquid line L4, a first connection portion J1, and a first treated water line L2. The first cleaning liquid line L4 and the first treated water line L2 are connected via the first connection portion J1.

The first treated water line L2 constitutes a part of the treated water line L23 and constitutes a part of the cleaning liquid line L42. The first treated water line L2 constituting a part of the cleaning liquid line L42 is also referred to as “second cleaning liquid line L2”.
The first cleaning liquid line L4 is a line that connects the cleaning liquid tank 7 and the first connection portion J1. The second cleaning liquid line L2 is a line that connects the first connection portion J1 and the secondary region 22 of the filtration apparatus 2.

The first cleaning liquid line L4 is connected to the treated water line L23 at the first connection portion J1. The upstream end of the first cleaning liquid line L4 is connected to the cleaning liquid tank 7.
The cleaning liquid tank 7 is a tank that stores the cleaning liquid W3. The cleaning liquid tank 7 is connected to the upstream end of the cleaning liquid line L42 (first cleaning liquid line L4). As the cleaning liquid W3, a known cleaning liquid containing an oxidizing agent, a surfactant, a chelating agent, and the like can be used. In the case of MBR filtration, an aqueous sodium hypochlorite solution is preferably used.

  The cleaning pump 62 is connected in the middle of the first cleaning liquid line L4. The cleaning pump 62 supplies the cleaning liquid W3 to the filtration membrane module 23 from the secondary side to the primary side. According to the cleaning pump 62, the cleaning liquid W3 stored in the cleaning liquid tank 7 is supplied to the secondary region 22 of the filtration apparatus 2 through the cleaning liquid line L42 (the first cleaning liquid line L4 and the second cleaning liquid line L2). can do.

  The cleaning liquid valve 61 is disposed downstream of the cleaning pump 62 in the first cleaning liquid line L4 (first connection portion J1), more specifically, between the cleaning liquid check valve 63 (described later) and the first connection portion J1. Is provided. According to the cleaning liquid valve 61, the first cleaning liquid line L4 can be opened and closed between the first connection portion J1 and the cleaning pump 62.

  The cleaning liquid check valve 63 is provided between the cleaning liquid valve 61 and the cleaning pump 62 in the first cleaning liquid line L4. The cleaning liquid check valve 63 is a valve that allows fluid to flow only in the direction from the first end on the cleaning liquid tank 7 side in the first cleaning liquid line L4 toward the first connection portion J1.

  The system control device 8 controls the entire filtering member cleaning system 1 of the present embodiment. The system control device 8 is electrically connected to an element to be controlled among the elements constituting the filter member cleaning system 1. Specifically, the system control device 8 is electrically connected to the pressure sensor 3, the treated water valve 41, the filtration pump 42, the cleaning liquid valve 61, and the cleaning pump 62.

  The system control device 8 includes a determination unit 81, a filtration control unit 82, and a cleaning control unit 83. The determination unit 81 is electrically connected to the pressure sensor 3. The filtration control unit 82 is electrically connected to the treated water valve 41 and the filtration pump 42. The cleaning control unit 83 is electrically connected to the cleaning liquid valve 61 and the cleaning pump 62.

  The determination unit 81 can set a predetermined threshold value, and determines whether the cleaning pump 62 is activated based on the set threshold value. For example, the predetermined threshold value is appropriately input to the worker by an operation.

  The details of the operation of determining the activation of the cleaning pump 62 by the determination unit 81 will be described later. For example, the determination unit 81 sets the threshold value to the post-cleaning pressure difference value after the supply of the cleaning liquid W3 by the cleaning pump 62 is completed. Reset the value to a value with a predetermined offset value added. The post-cleaning pressure difference value is calculated based on a “measured pressure difference value” that is a pressure difference measured by the pressure sensor 3.

  The determination unit 81 calculates the post-cleaning pressure difference value by averaging all or some of the plurality of measured pressure difference values measured by the pressure sensor 3. The determination unit 81 resets the threshold value after the cleaning liquid W3 has been supplied by the cleaning pump 62 and while the filtration pump 42 is being activated. The determination unit 81 determines to start the cleaning pump 62 when the post-cleaning pressure difference value is equal to or greater than a threshold value.

The filtration control unit 82 performs control of opening / closing the treated water valve 41, control of activation of the filtration pump 42, and the like.
The cleaning control unit 83 performs control of opening / closing of the cleaning liquid valve 61, control of activation of the cleaning pump 62, and the like at a predetermined periodic cleaning timing or based on a determination result by the determination unit 81.

  The pressure sensor 3 starts measuring the pressure difference after the supply of the cleaning liquid W3 by the cleaning pump 62 and after the filtration pump 42 is started. In addition, the pressure sensor 3 starts measuring the pressure difference after the lapse of a predetermined time after the supply of the cleaning liquid W3 by the cleaning pump 62 is completed.

  Next, an example of the operation of the filtration member cleaning system 1 of the present embodiment will be described with reference to FIGS. FIG. 2 is a diagram illustrating one cycle of an example of the operation of the filtration member cleaning system illustrated in FIG. 1. FIG. 3 is a flowchart showing an example of the operation of the filtration member cleaning system shown in FIG. FIG. 4 is a diagram showing the timing of measurement of the pressure difference.

  In this embodiment, as shown in FIG. 2, in the filtration member cleaning system 1, after the cleaning process (reverse cleaning) is performed, a plurality of sets of filtration process and pause are repeatedly performed, and the next cleaning process ( One cycle until the reverse cleaning is performed will be described. In this embodiment, for convenience of explanation, it is assumed that after the cleaning process is performed, the filtration process and the rest set are repeated four times, and then the cleaning process is performed as a periodic cleaning. In addition, even before the fourth set of filtration processing is completed, if the predetermined cleaning conditions are satisfied, the cleaning processing is performed ahead of schedule separately from the periodic cleaning (hereinafter, this cleaning is also referred to as “forward cleaning”). Is supposed to do.

  First, an example (periodic cleaning flow) in which one cycle including one cleaning process and four sets of filtration processes and pauses is performed, and the next cleaning process is performed as a periodic cleaning will be described. Periodic cleaning is cleaning performed periodically at a predetermined frequency regardless of the degree of blockage of the filtration membrane module 23. The regular cleaning is performed, for example, after a predetermined number of times (four times in the present embodiment) of filtration processing or every predetermined time.

In the periodic cleaning flow, as shown in FIG. 2, immediately after the cleaning process (required time: t1), four sets of the filtration process (required time: t2) and the rest (required time: t5) are repeated. Thereby, one cycle of the regular cleaning flow is completed. Thereafter, at the beginning of the next cycle, a cleaning process is performed as a regular cleaning.
In the present embodiment, measurement of the pressure difference (transmembrane pressure difference) (required time: t = 4) is started after a lapse of a predetermined time (interval) t3 from the start of each filtration process. The measurement of the pressure difference is stopped at the same time as or before or after the filtration process is stopped.

  Next, in this embodiment, an example of detecting the possibility of clogging of the filtration membrane module 23 before regular cleaning, and starting the cleaning process (supplying the cleaning liquid W3) before the end of one cycle (forward cleaning flow) Will be described.

  With reference to FIG. 2 and FIG. 4 together with FIG. 3, a forward cleaning flow in the present embodiment will be described. Of the steps (ST) in the flowchart shown in FIG. 3, the steps that can be shown in FIG. 2 or 4 are shown in FIG. 2 or FIG. 4.

  As shown in FIG. 3, in step ST <b> 1 (see also FIGS. 2 and 4), the cleaning control unit 83 opens the cleaning liquid valve 61 and starts the cleaning pump 62. Accordingly, the cleaning liquid W3 stored in the cleaning liquid tank 7 is supplied from the secondary side to the filtration membrane module 23 via the cleaning liquid line L42 (the first cleaning liquid line L4 and the second cleaning liquid line L2). In this way, the cleaning process for the filtration membrane module 23 is started, and the filtration membrane module 23 is back-washed with the cleaning liquid W3. The cleaning process is performed over the required time t1.

  As shown in FIG. 3, in step ST <b> 2 (see also FIGS. 2 and 4), after a lapse of a required time t <b> 1 from the start of the cleaning process, the cleaning control unit 83 closes the cleaning liquid valve 61 and cleans the pump 62. Stop. Thereby, the supply of the cleaning liquid W3 to the filtration membrane module 23 is stopped, and the cleaning process (reverse cleaning) is completed.

  As shown in FIG. 3, after completion of the cleaning process, in step ST3 (see also FIGS. 2 and 4), the filtration control unit 82 opens the treated water valve 41 and activates the filtration pump 42. Thereby, the filtration process of the to-be-processed water W1 is started, and the to-be-processed water W1 stored in the primary side area | region 21 (filtration process water tank 24) of the filter 42 for filtration passes the filtration membrane module 23, and is on the secondary side. Move to region 22. As a result, treated water W2 obtained by subjecting the treated water W1 to filtration is obtained. The treated water W2 is supplied to the treated water tank 5 via the treated water line L23 (the first treated water line L2 and the second treated water line L3). The filtration process is performed over the required time t2.

  As shown in FIGS. 2 and 4, after a predetermined time t3 has elapsed after the start of the filtration process (after the start-up of the filtration pump 42), as shown in FIG. Causes the pressure sensor 3 to start measuring the pressure difference. The predetermined time (interval) t3 is, for example, 10 seconds or more.

  As shown in FIG. 3, in step ST5 (see also FIG. 4), the pressure sensor 3 repeatedly measures the pressure difference. The pressure difference measured by the pressure sensor 3 is also referred to as “measured pressure difference value”. The pressure difference is measured over the required time t4.

The pressure difference is measured as follows.
As shown in FIG. 4, in the pressure difference measurement period over the required time t4, the pressure difference is measured a plurality of times at predetermined measurement intervals t41. For example, the pressure difference is measured nine times during the pressure difference measurement period. Then, every time the pressure difference is measured, an average value of the pressure difference in the measurement period of the pressure difference is calculated.

  Specifically, for example, when measuring the pressure difference for the second time, the average value of the first and second measurement values is calculated. When measuring the pressure difference for the third time, the average value of the first to third measurement values is calculated (updated). When measuring the (last) ninth pressure difference, the average value of the first to ninth measurement values is calculated (updated). The average value of the first to ninth measurement values calculated in the (final) ninth pressure difference measurement is referred to as a “post-wash pressure difference value”.

  As shown in FIGS. 2 and 4, after the required time t <b> 2 has elapsed after the start of the first set of filtration processing, the filtration control unit 82 closes the treated water valve 41 and filters 42 for filtration. Stop. As a result, the first set of filtration processing is stopped.

  As shown in FIGS. 2 and 4, after the first set of filtration processing is stopped, the filtration processing is paused. The suspension of the filtration process is performed over the required time t5. Such a set of filtration and rest is repeated four times.

As described above, when four sets of filtration treatment and pause are performed, one cycle of the periodic cleaning flow is completed.
On the other hand, in the forward cleaning flow, the forward cleaning is performed before one cycle of the regular cleaning flow ends (before the cleaning process of the next cycle is started).
Hereinafter, a flow until forward cleaning is performed will be described.

As shown in FIG. 3, in step ST6, the determination unit 81 determines whether or not the measured pressure difference value is equal to or greater than a threshold value (measured pressure difference value ≧ threshold value) within the pressure difference measurement period. When the measured pressure difference value is less than the threshold value (measured pressure difference value <threshold value) (NO), the process returns to step ST5 and the measurement of the pressure difference is repeated. If the measured pressure difference value is equal to or greater than the threshold value (measured pressure difference value ≧ threshold value) (YES), the process proceeds to step ST7.
In the present embodiment, the threshold is set in advance by the operator. Since the secondary region 22 of the filtration apparatus 2 has a negative pressure, the threshold value is set to an absolute value (positive value) of the negative pressure.

  As shown in FIG. 3, when the measured pressure difference value is equal to or greater than the threshold value (measured pressure difference value ≧ threshold value) (YES), in step ST7 (see also FIGS. 2 and 4), the determination unit 81 Add the offset value to the current post-wash pressure difference value and reset the threshold. The post-cleaning pressure difference value is calculated based on a “measured pressure difference value” that is a pressure difference measured by the pressure sensor 3.

Specifically, the post-cleaning pressure difference value is calculated by averaging all of the plurality of measured pressure difference values measured by the pressure sensor 3 (9 times in this embodiment).
The post-cleaning pressure difference value can be calculated by averaging a part of the plurality of measured pressure difference values measured by the pressure sensor 3 (for example, 7 out of 9 times). The maximum value among the measured pressure difference values can be adopted, and the minimum value among the plurality of measured pressure difference values measured can also be adopted.

In the present embodiment, since the secondary region 22 of the filtration apparatus 2 has a negative pressure, the offset value is set to a negative value. The offset value is preset by the operator and stored in the determination unit 81. The offset value is, for example, −15 kPa.
In the present embodiment, since the measured pressure difference value measured by the pressure sensor 3 is measured as a negative pressure, a negative value offset value is added to the positive measured pressure difference value, whereby a threshold value is obtained. Will be reset. Accordingly, the absolute value of the reset threshold value is smaller than the absolute value of the threshold value before the resetting.

  By resetting the threshold value in this way, in the filtration process after the cleaning process of the next cycle, the measured pressure difference value is likely to exceed the threshold value (YES in step ST6). That is, by performing the forward cleaning at the stage when the filtration membrane module 23 may be clogged, the filtration membrane module 23 is excessively used to the extent that the clogging of the filtration membrane module 23 cannot be eliminated even by performing reverse cleaning. Can be suppressed. Thereby, the lifetime of the filtration membrane module 23 can be lengthened.

  As shown in FIG. 3, in step ST8 (see also FIG. 2), the measurement of the pressure difference is stopped. Specifically, the determination unit 81 stops the pressure difference measurement by the pressure sensor 3.

  As shown in FIG. 3, the filtration process is stopped in step ST9 (see also FIG. 2). Specifically, the filtration control unit 82 closes the treated water valve 41 and stops the filtration pump 42.

As shown in FIG. 3, even after step ST9 (after the filtration process is stopped) and before one cycle is completed, the process returns to step ST1 and the next cleaning process (one cycle) is started.
As shown in FIG. 3, in step ST <b> 1 (see also FIGS. 2 and 4), the cleaning control unit 83 opens the cleaning liquid valve 61 and starts the cleaning pump 62. Accordingly, the cleaning liquid W3 stored in the cleaning liquid tank 7 is supplied from the secondary side to the filtration membrane module 23 via the cleaning liquid line L42 (the first cleaning liquid line L4 and the second cleaning liquid line L2). Thereby, the cleaning process of the filtration membrane module 23 as the forward cleaning is started, and the reverse cleaning of the filtration membrane module 23 is performed by the cleaning liquid W3.

  Here, as described above, since the threshold is reset, the determination unit 81 determines whether the cleaning liquid valve 61 and the cleaning pump 62 are activated based on the reset threshold. Then, based on the determination result based on the reset threshold, the cleaning control unit 83 starts activation of the cleaning liquid valve 61 and the cleaning pump 62.

According to the filtration member cleaning system 1 of the present embodiment, for example, the following effects are exhibited.
In the present embodiment, a predetermined threshold value can be set, and a determination unit 81 that determines the activation of the cleaning pump 62 based on the set threshold value, and the cleaning pump 62 based on the determination result by the determination unit 81. And a cleaning control unit 83 that controls activation. After the supply of the cleaning liquid W3 by the cleaning pump 62 is completed, the determination unit 81 uses a measured pressure difference value that is a pressure difference measured by the pressure sensor 3 as a threshold value. Is reset to a value obtained by adding a predetermined offset value to the post-cleaning pressure difference value calculated based on

Therefore, even before the regular cleaning process (periodic cleaning) of the filtration membrane module 23, forward cleaning (forward cleaning) is performed based on a predetermined condition (threshold). Therefore, the reverse cleaning of the filtration membrane module 23 can be performed at an appropriate timing. In addition, the threshold value is reset every time forward cleaning is performed, and the measured pressure difference value easily exceeds the threshold value, and as a result, the timing at which forward cleaning is performed is advanced.
As described above, according to the present embodiment, the measured pressure difference value easily exceeds the threshold value by resetting the threshold value every time the cleaning process is performed. Therefore, compared with the case where the cleaning process is periodically performed based on certain conditions, the membrane filter 23 is back-washed at an effective timing while suppressing the occurrence of clogging of the membrane filter module 23. Can do.

  Further, in the present embodiment, the pressure sensor 3 starts measuring the pressure difference after the end of the supply of the cleaning liquid W3 by the cleaning pump 62 and after a lapse of a predetermined time (t3). Immediately after the supply of the cleaning liquid W3 and immediately after the start of the filtration pump 42, the measured value of the pressure difference (measured pressure difference value) tends to be unstable, but such an unstable measured pressure difference value is excluded. Since the average value of the measured pressure difference values can be calculated above, the accuracy of the average value of the measured pressure difference values (that is, the post-cleaning pressure difference value) is improved.

As mentioned above, although preferred embodiment of this invention was described, this invention can be implemented with a various form, without being limited to embodiment mentioned above.
For example, in the said embodiment, although the filtration processing apparatus 2 is equipped with the immersion type filtration membrane module 23 as a filtration member, it is not restrict | limited to this. The filtration processing apparatus 2 may be an apparatus including an external pressure type filtration membrane module, or may be an activated carbon filtration apparatus or a sand filtration apparatus using a granular filter medium.
In the above embodiment, the water to be treated circulation means is constituted by a filtration pump 42 as a suction pump. However, when the filtration treatment apparatus includes an external pressure type filtration membrane module, it is constituted by a discharge pump. You can also. In this case, the pressure difference measured by the pressure sensor 3 is measured as a positive pressure.

In the above-described embodiment, the cleaning control unit 83 serving as a control unit controls ON / OFF of activation of the filtration pump 42, but is not limited thereto. The cleaning control unit 83 can also control the amount and concentration of the cleaning liquid.
The measurement of the pressure difference by the pressure sensor 3 can also be performed simultaneously with or immediately after the supply of the cleaning liquid by the cleaning pump 62.
The number of times of filtration treatment in one cycle of the normal flow (4 times in the embodiment), and the number of times of pressure difference measurement in the measurement period of pressure difference corresponding to one filtration treatment (9 times in the embodiment) are all. Not limited.

DESCRIPTION OF SYMBOLS 1 Filtration member washing | cleaning system 2 Filtration processing apparatus 21 Primary side area | region 22 Secondary side area | region 23 Filtration membrane module (filtration member)
3 Pressure sensor (pressure difference measuring means)
42 Filtration pump (Treatment water distribution means)
5 Treated water tank 62 Cleaning pump (cleaning liquid supply means)
7 Cleaning liquid tank 81 Judgment part (judgment means)
82 Filtration control unit 83 Cleaning control unit (control means)
W1 Water to be treated W2 Water to be treated W3 Cleaning liquid

Claims (5)

A filtration member that passes the treated water from the primary side toward the secondary side and filters the treated water, and a primary side region and a secondary side region partitioned by the filtering member, and the primary A filtration device for filtering the treated water by allowing the treated water to pass through the filtration member from the side region toward the secondary region;
Treated water circulation means for circulating the treated water from the primary area toward the secondary area;
Cleaning liquid supply means for supplying a cleaning liquid to the filter member from the secondary side toward the primary side;
Pressure difference measuring means for measuring a pressure difference between the primary side region and the secondary side region;
A determination unit capable of setting a predetermined threshold value, and determining the activation of the cleaning liquid supply unit based on the set threshold value;
Control means for controlling activation of the cleaning liquid supply means based on a determination result by the determination means;
With
The determination means sets the threshold value to a post-cleaning pressure difference value calculated based on a measured pressure difference value that is a pressure difference measured by the pressure difference measuring means after the cleaning liquid supply by the cleaning liquid supply means is completed. A filtration member cleaning system that resets a value obtained by adding a predetermined offset value.   2. The filtration member cleaning system according to claim 1, wherein the determination unit performs the resetting of the threshold value after completion of the supply of the cleaning liquid by the cleaning liquid supply unit and during activation of the treated water circulation unit. The pressure difference measuring means starts measurement of the pressure difference after the supply of the cleaning liquid by the cleaning liquid supply means and after activation of the treated water circulation means,
The filtration member cleaning system according to claim 2, wherein the determination unit calculates the post-cleaning pressure difference value by averaging all or a part of the plurality of measured pressure difference values measured by the pressure difference measurement unit.   4. The filtration member cleaning system according to claim 1, wherein the pressure difference measuring unit starts measuring the pressure difference after a predetermined time elapses after the supply of the cleaning solution by the cleaning solution supplying unit. 5.   5. The filtration member cleaning system according to claim 1, wherein the control unit activates the cleaning liquid supply unit when the measured pressure difference value is equal to or greater than the threshold value. 6.

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