JP2017018859A - Membrane washing control method, membrane washing control device, and water treatment system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a membrane washing control method that can efficiently wash a membrane filter with a reduced amount of chemical liquid, and to provide a membrane washing control device, and a water treatment system.SOLUTION: The membrane washing control method includes: an acquisition process; and a determination step. The acquisition process acquires a transmembrane pressure difference value of the membrane filter or membrane filtration resistance value immediately after washing the membrane filter with the chemical liquid. The determination step determines washing strength in performing the next chemical liquid washing on the basis of the transmembrane pressure difference value or membrane filtration resistance value.SELECTED DRAWING: None

Description

  Embodiments described herein relate generally to a membrane cleaning control method, a membrane cleaning control device, and a water treatment system.

  In a water treatment system, a filtration membrane is generally used for solid-liquid separation of water to be treated. However, by continuing filtration with a filtration membrane, turbidity, suspended substances, etc. adhere or accumulate on the membrane surface or in the membrane, resulting in clogging (fouling) of the membrane. When fouling occurs, the pressure difference between the treated water side (primary side) and the permeated water side (secondary side) of the membrane, that is, the transmembrane pressure (TMP) increases. When TMP rises, the permeation flux decreases, and it becomes a problem because it becomes impossible to secure treated water stably.

  Therefore, when the TMP value reaches a predetermined value, the filtration membrane is washed with a chemical solution. At present, the concentration and cleaning time of the chemical solution used for cleaning the chemical solution are often not changed from the initial values. Therefore, for example, when the initially set concentration of the chemical solution is low or when the cleaning time is short, the filtration membrane is not sufficiently cleaned, and the TMP value may increase rapidly each time the cleaning is repeated. Further, when the initially set concentration of the chemical solution is high or when the cleaning time is long, excessive cleaning is performed, and the cost of the chemical solution may increase, or the film life may be reduced.

JP 2013-202471 A

  The problem to be solved by the present invention is to provide a membrane cleaning control method, a membrane cleaning control device, and a water treatment system capable of efficiently cleaning a filtration membrane with a small amount of chemical solution.

The film cleaning control method of the embodiment has an acquisition step and a determination step. In the acquisition step, the filtration membrane is washed with a chemical solution, and the transmembrane differential pressure value (TMP ₀ ) or membrane filtration resistance value of the filtration membrane immediately after resumption of filtration is obtained. In the determination step, the cleaning strength for the next chemical cleaning is determined based on the transmembrane differential pressure value (TMP ₀ ) or membrane filtration resistance value of the filtration membrane immediately after the filtration membrane is washed with the chemical solution and filtration is resumed. To do.

The schematic block diagram which shows the water treatment system of embodiment. The schematic block diagram which shows the film | membrane cleaning control apparatus of embodiment. The flowchart which shows the flow of the film | membrane cleaning control method of embodiment.

Hereinafter, a membrane cleaning control method, a membrane cleaning control device, and a water treatment system of an embodiment will be described with reference to the drawings.
In the drawings used in the following description, in order to make each component easy to see, the scale of the size may be changed depending on the component. In addition, the materials, dimensions, and the like exemplified in the following description are examples, and the embodiment is not necessarily limited thereto, and can be implemented with appropriate modifications.

  First, the water treatment system of embodiment is demonstrated with reference to FIG. Drawing 1 is a schematic structure figure showing a water treatment system of an embodiment. As shown in FIG. 1, a water treatment system 1 includes an anoxic tank 2, an aerobic tank (tank) 3, a membrane module 4 provided with a filtration membrane, a pressure gauge 5, a treated water tank 6, and a chemical liquid tank. 7, a chemical concentration adjusting tank 8, a cleaning chemical discharge tank 9, and a film cleaning control device 10. The water treatment system 1 decomposes and removes organic substances and nitrogen components from water containing organic substances and nitrogen components such as ammoniacal nitrogen (hereinafter referred to as “raw water”), and treats the treated water after the decomposition and removal with the membrane module 4. It is a system that discharges to the outside through.

  The anoxic tank 2 is connected to a water supply path L1, and raw water is supplied from the outside through the water supply path L1. Moreover, the return path L2 is connected to the anaerobic tank 2, and the mixed solution of raw water and activated sludge circulates through the anoxic tank 2 and the aerobic tank 3 through the return path L2.

In the anaerobic tank 2, there is activated sludge composed of various microorganism groups. The activated sludge is circulated through the anoxic tank 2, the aerobic tank 3, and the return path L2. The anoxic tank 2 is maintained in an anoxic state, and the action of denitrifying bacteria in the activated sludge is active. In the anoxic tank 2, nitrate nitrogen can be decomposed into nitrogen gas by the action of denitrifying bacteria. The generated nitrogen gas is released into the atmosphere to remove nitrogen components in the water. A part of the organic matter is reduced in molecular weight by the action of microorganisms in the activated sludge and is also decomposed to CO ₂ by being used for denitrifying bacteria.

  A stirrer 11 is provided inside the anaerobic tank 2. By the stirrer 11, the contact efficiency between the raw water and the activated sludge in the oxygen-free tank 2 is increased, thereby promoting the decomposition of nitrate nitrogen. The water treated in the anaerobic tank 2 is supplied to the aerobic tank 3.

  In the aerobic tank 3, the mixed solution of raw water and activated sludge supplied from the previous anaerobic tank 2 is processed. The aerobic tank 3 has activated sludge composed of various microbial groups as in the anoxic tank.

A blower 12 is connected to the aerobic tank 3. The inside of the aerobic tank 3 is aerated by the air supplied from the blower 12, the air is sent into the aerobic tank 3 and the membrane surface of the membrane module 4 can be cleaned. The aerobic tank 3 is maintained in an aerobic state, and the functions of aerobic microorganisms and nitrifying bacteria in the activated sludge are active. The organic matter is oxidized to CO ₂ by the action of the aerobic microorganism group, and the ammonia nitrogen in the aerobic tank 3 is oxidized to nitrate nitrogen by the action of the nitrifying bacteria. The produced nitrate nitrogen is supplied to the anoxic tank 2 through the return path L2, and is decomposed in the anoxic tank 2.

  The return path L2 has one end connected to the aerobic tank 3 and the other end connected to the oxygen-free tank 2. A pump 13 is provided in the return path L2, and the pump 13 can circulate and supply the mixed solution of raw water and activated sludge in the aerobic tank 3 to the anoxic tank 2 through the return path L2. Nitrate nitrogen generated by the action of nitrifying bacteria is also supplied to the anoxic tank 2. The surplus activated sludge may be pulled out from the middle of the return path L2.

  The membrane module 4 is provided so as to penetrate into the aerobic tank 3. The membrane module 4 can separate and filter out water from which organic substances and nitrogen components have been removed from the mixed solution (hereinafter referred to as “treated water”).

  The material and shape of the filtration membrane are not particularly limited as long as they can separate and filter turbidity and solid matter from the water to be treated. Specific examples include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), chlorinated polyethylene, and ceramic. Examples of the shape of the filtration membrane include a hollow fiber shape, a flat membrane shape, and a monolith shape.

  The membrane module 4 is connected to the treated water tank 6 via the water supply path L3. In the water supply path L3, a switching valve 14, a switching valve 15, and a pump 16 are provided in order from the side closer to the filtration membrane.

  By opening and closing the switching valve 14, the supply of the chemical solution prepared in the chemical concentration adjusting tank 8 to the membrane module 4 can be controlled. Further, by opening and closing the switching valve 15, it is possible to control the supply of the chemical liquid after the chemical liquid cleaning to the cleaning chemical liquid discharge tank 9. Further, the treated water filtered by the membrane module 4 can be supplied to the treated water tank 6 by the pump 16.

  The pressure gauge 5 is provided between the switching valve 15 and the pump 16. By measuring the pressure of the treated water flowing through the water supply path L3 with the pressure gauge 5, the pressure difference between the primary side pressure and the secondary side pressure of the filtration membrane, that is, the transmembrane pressure difference (TMP) can be obtained. it can.

  The treated water tank 6 is connected to the membrane module 4 via the water supply path L3. The treated water tank 6 is supplied with treated water from the membrane module 4 via the water supply path L3. The treated water tank 6 is connected to the water supply path L4. A part of the treated water supplied to the treated water tank 6 can be discharged to the outside and the rest can be stored in the treated water tank 6 by the water supply path L4.

  Moreover, the treated water tank 6 is connected to the chemical concentration adjusting tank 8 through the water supply path L5. A pump 17 is provided in the water supply path L5, and the treated water stored in the treated water tank 6 by the pump 17 can be supplied to the chemical concentration adjusting tank 8.

  The pump 17 can be controlled in flow rate by an inverter, and can adjust the supply amount of treated water to the chemical concentration adjusting tank 8 based on the concentration of the chemical determined by the cleaning condition determination unit 33 (see FIG. 2). it can.

  The chemical tank 7 is connected to the chemical concentration adjusting tank 8 through the water supply path L6. The chemical solution tank 7 is a tank for storing a chemical solution used when the membrane module 4 is subjected to chemical cleaning.

  The chemical solution stored in the chemical solution tank 7 is not particularly limited as long as the membrane module 4 can be cleaned with the chemical solution. Moreover, you may select a chemical | medical solution suitably according to the kind of deposit | attachment adhering to the filtration membrane.

  The chemical solution used for the organic deposit is not particularly limited as long as it is a chemical corresponding to the organic deposit. Specific examples include sodium hypochlorite and sodium hydroxide.

  In addition, the chemical liquid used for the inorganic deposit is not particularly limited as long as it is a chemical corresponding to the inorganic deposit. Specific examples include oxalic acid and citric acid.

  The chemical tank 7 may store a plurality of chemical liquids and appropriately select a chemical liquid to be used for chemical liquid cleaning based on the cleaning strength determined by the cleaning strength determination unit 32. Specifically, for example, when the TMP value immediately after the chemical cleaning of the membrane module 4 is equal to or lower than a predetermined value, the chemical liquid for the organic deposit is used, and when the TMP value becomes larger than the predetermined value, the inorganic system is used. You may use a chemical | medical solution separately, such as using the chemical | medical solution with respect to the deposit | attachment.

  A pump 18 is provided in the water supply path L <b> 6, and the chemical liquid stored in the chemical liquid tank 7 can be supplied to the chemical liquid concentration adjusting tank 8 by the pump 18. The supply amount of the chemical liquid to the chemical concentration adjusting tank 8 can be adjusted based on the concentration of the chemical determined by the cleaning condition determination unit 33 (see FIG. 2) by the inverter mounted on the pump 18.

  The chemical concentration adjusting tank 8 is connected to the treated water tank 6 and the chemical liquid tank 7 via the water supply paths L5 and L6, the treated water is supplied from the treated water tank 6, and the chemical liquid is supplied from the chemical liquid tank 7. In the chemical solution concentration adjusting tank 8, the concentration of the chemical solution can be adjusted by mixing the treated water and the chemical solution.

  The chemical concentration adjusting tank 8 is connected to the switching valve 14 via the water supply path L7. A pump 19 is provided in the water supply path L7, and the chemical liquid whose concentration is adjusted in the chemical liquid concentration adjusting tank 8 by the pump 19 can be supplied from the secondary side of the membrane module 4.

  The pump 19 is a pump that supplies a necessary amount of chemical solution into the membrane of the membrane module 4. The required amount of the chemical solution is determined by the volume inside the membrane, and becomes a certain amount of the chemical solution. The state in which the chemical solution enters the inside of the film is maintained for the cleaning time determined by the cleaning condition determination unit 33 (see FIG. 2).

  The cleaning chemical liquid discharge tank 9 is connected to the switching valve 15 through the water supply path L8. After the elapse of the cleaning time determined by the cleaning condition determining unit 33, the chemical liquid is discharged to the cleaning chemical liquid discharge tank 9 through this path.

  The membrane cleaning control device 10 is connected to a pressure gauge 5, pumps 17, 18, 19 and switching valves 14, 15 via signal lines C1, C2, C3, C4, C5, and C6, respectively. FIG. 2 is a schematic configuration diagram showing the film cleaning control device 10. As shown in FIG. 2, the film cleaning control apparatus 10 includes a value acquisition unit 31, a cleaning strength determination unit 32, a cleaning condition determination unit 33, and a film cleaning control unit 34. Each functional unit included in the film cleaning control device 10 is realized by executing a program read into a RAM (Random Access Memory) by a CPU (Central Processing Unit).

  The value acquisition unit 31 is connected to the pressure gauge 5 via the signal line C1. The value acquisition unit 31 acquires the pressure on the secondary side of the filtration membrane measured by the pressure gauge 5. The value acquisition unit 31 acquires the TMP value based on the acquired pressure on the secondary side of the filtration membrane.

  Based on the TMP value acquired by the value acquisition unit 31, the cleaning strength determination unit 32 determines the cleaning strength when the membrane module 4 is next subjected to chemical cleaning. The cleaning strength may be divided into two stages or may be divided into three or more stages.

  Based on the cleaning strength determined by the cleaning strength determination unit 32, the cleaning condition determination unit 33 determines the concentration of the chemical solution used for the chemical solution cleaning or the cleaning time for the chemical solution cleaning.

  The membrane cleaning control unit 34 is connected to the pumps 17, 18, 19 and the switching valves 14, 15 via signal lines C 2, C 3, C 4, C 5, C 6. The film cleaning control unit 34 controls the supply amount of the chemical solution supplied from the chemical solution tank 7 to the chemical solution concentration adjusting tank 8 based on the concentration of the chemical solution determined by the cleaning condition determination unit 33. As a result, the concentration of the chemical solution is adjusted to the concentration of the chemical solution determined by the cleaning condition determination unit 33 in the chemical solution concentration adjustment tank 8.

  During the cleaning time determined by the cleaning condition determination unit 33, the film cleaning control unit 34 closes the switching valve 14 and maintains the state in which the chemical solution has entered the film. After the elapse of the cleaning time determined by the cleaning condition determination unit 33, the chemical liquid is discharged to the cleaning chemical liquid discharge tank 9 through the switching valves 14 and 15 and the water supply path L8.

Next, the membrane cleaning control method by the water treatment system 1 described above will be described with reference to FIG. 1 and FIG.
First, before explaining the membrane cleaning control method of the embodiment, a raw water treatment method by the water treatment system 1 will be explained. In the water treatment system 1, first, raw water is supplied to the anoxic tank 2 through the water supply path L1. The raw water supplied to the anaerobic tank 2 is circulated through the anaerobic tank 2 and the aerobic tank 3 through the return path L2 in a state of being mixed with the activated sludge.

In the anaerobic tank 2, nitrate nitrogen is decomposed into nitrogen gas by the action of denitrifying bacteria. The generated nitrogen gas is released into the atmosphere to remove nitrogen components in the water. A part of the organic matter is reduced in molecular weight by the action of microorganisms in the activated sludge and is also decomposed to CO ₂ by being used for denitrifying bacteria.

Also within the aerobic tank 3, by the action of aerobic microorganisms, organic matter is low molecular weight, the majority is decomposed into water and CO _2. Furthermore, ammonia nitrogen in the aerobic tank 3 is oxidatively decomposed into nitrate nitrogen by the action of nitrifying bacteria. The produced nitrate nitrogen is supplied to the anoxic tank 2 through the return path L2, and is decomposed in the anoxic tank 2.

  Next, water (treated water) from which organic substances and nitrogen components have been removed is separated, filtered and taken out by the membrane module 4.

  Raw water is treated by the above steps. As a result of the above processing, turbidity, suspended substances, and the like adhere or deposit on the membrane surface of the membrane module 4 or in the membrane, so that the membrane module 4 needs to be cleaned by the membrane cleaning control method.

  Next, the film cleaning control method of the embodiment will be described. FIG. 3 is a flowchart showing a flow of the film cleaning control method of the embodiment. As shown in FIG. 3, the film cleaning control method of the embodiment includes an acquisition step S1, a determination step S2, and a cleaning step S3. In the membrane cleaning control method of the embodiment, the membrane module 4 is subjected to chemical cleaning by performing the acquisition step S1, the determination step S2, and the cleaning step S3 in this order. The chemical cleaning is performed when the TMP value of the filtration membrane exceeds a predetermined value.

  In acquisition process S1, the TMP value of the filtration membrane immediately after restarting membrane filtration after carrying out chemical | medical solution washing | cleaning of the membrane module 4 is acquired. Specifically, first, the pressure value on the secondary side of the filtration membrane immediately after the membrane filtration is resumed after the membrane module 4 is cleaned with the chemical solution is transmitted to the value acquisition unit 31 via the signal line C1. To do. Next, the TMP value is acquired by the value acquisition unit 31 based on the pressure value on the secondary side of the filtration membrane transmitted from the pressure gauge 5.

  In the determination step S2, the cleaning strength when performing the next chemical cleaning is determined based on the acquired transmembrane pressure difference value. Specifically, first, the TMP value acquired by the value acquisition unit 31 is transmitted to the cleaning intensity determination unit 32. In the cleaning strength determination unit 32, conditions for determining the cleaning strength from the TMP value are set in advance as shown in Table 1 below, and the cleaning strength is determined based on the transmitted TMP value.

  In the cleaning step S3, the concentration and cleaning time of the chemical solution are determined based on the determined cleaning strength, and the chemical solution cleaning is performed based on the determined concentration and cleaning time of the chemical solution. Specifically, first, the cleaning strength determined by the cleaning strength determination unit 32 is transmitted to the cleaning condition determination unit 33. In the cleaning strength determination unit 32, as shown in Table 1 above, conditions for determining the chemical concentration and cleaning time from the cleaning strength are set in advance, and the chemical concentration and cleaning time are determined based on the transmitted cleaning strength. To decide.

  Next, the chemical concentration and the cleaning time determined by the cleaning condition determination unit 33 are transmitted to the film cleaning control unit 34. The membrane cleaning control unit 34 determines the supply amount of the water to be treated and the chemical solution to the chemical concentration adjusting tank 8 based on the concentration of the chemical solution, and the pump 17 and the pump via the signal lines C2 and C3 based on the determination. 18 is controlled.

A predetermined amount of treated water and chemical solution are supplied to the chemical concentration adjusting tank 8 by the pump 17 and the pump 18. Here, when the transmembrane pressure difference value (TMP ₀ ) immediately after resuming membrane filtration after chemical solution cleaning is _Pn or less, sodium hypochlorite is used as the chemical solution used for chemical solution cleaning, and _Pn or more Uses oxalic acid. Thereafter, in the chemical solution concentration adjusting tank 8, the chemical solution having the concentration determined by the cleaning condition determination unit 33 is prepared by diluting the chemical solution with treated water.

  Next, the membrane cleaning control unit 34 closes the switching valve 14 during the cleaning time determined by the cleaning condition determination unit 33, and maintains the state in which the chemical solution has entered the membrane. After the elapse of the cleaning time determined by the cleaning condition determination unit 33, the chemical liquid is discharged to the cleaning chemical liquid discharge tank 9 through the switching valves 14 and 15 and the water supply path L8.

Next, the membrane cleaning control unit 34 controls the switching valve 15 via the signal line C6 to discharge the chemical used in the chemical cleaning to the cleaning chemical discharge tank 9.
The membrane module 4 can be subjected to chemical cleaning by the above steps.

  In the above embodiment, the cleaning condition determination unit 33 determines the concentration of the chemical solution and the cleaning time based on the cleaning strength, but determines only one of the concentration of the chemical solution or the cleaning time, and the other sets the initial set value. It may be used.

  Although the flow rate of the pumps 17 and 18 is controlled by an inverter, a configuration in which the pump flow rate is controlled by a flow rate adjusting valve installed on the pump discharge side may be used.

According to the membrane cleaning control method of the embodiment described above, the filtration membrane can be efficiently cleaned with a small amount of chemical solution by having an acquisition step and a determination step.
The film cleaning control device 10 of the embodiment may be configured using a plurality of devices. For example, a part of the functional units of the film cleaning control apparatus 10 shown in FIG. 2 may be mounted on another apparatus, and the film cleaning control method may be executed by performing communication.

  The membrane cleaning control device 10 of the embodiment may be provided at a position away from each device of the water treatment system 1 and may be connected to a control device provided in the water treatment system 1 via a network. In this case, the membrane cleaning control device 10 acquires a value measured by a device such as the pressure gauge 5 through communication from the control device via a network. The film cleaning control device 10 determines the cleaning strength based on the acquired value. The membrane cleaning control device 10 transmits the determined cleaning strength to the control device included in the water treatment system 1 via the network. The control device provided in the water treatment system 1 performs cleaning based on the received cleaning intensity.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  In this specification, the chemical cleaning strength is determined based on the transmembrane pressure difference immediately after the resumption of filtration after the chemical cleaning, but in the treatment field where the flux fluctuation is large, it is better to make the determination based on the membrane filtration resistance. preferable.

The membrane filtration resistance is generally not directly measurable, but is known to be represented by the following general formula (1).
^{TMP = μJ P R ··· (1} )
In the above general formula (1), TMP is the transmembrane pressure (kPa), μ is the viscosity coefficient [kPa / d], J is the flux of treated water permeating through the membrane of the membrane module 4 [m / d], R Indicates membrane filtration resistance [1 / m], P indicates a power constant.

That is, the membrane filtration resistance R is represented by the following general formula (2).
R = TMP / μJ ^P (2)
In the general formula (2), the power constant P is usually an adjustment parameter set between 1 and 2.

  The flux can be measured continuously by dividing the amount of treated water filtered by the membrane of the membrane module 4 (filtered water amount) by the membrane area. Therefore, assuming that the viscosity coefficient is constant, TMP was divided by the power of the flux. The value corresponds to the membrane filtration resistance.

That is, the membrane filtration resistance R is represented by the following general formula (3).
^{R = B · TMP / J P} ··· (3)
In the above general formula (3), if B is a constant, the membrane filtration resistance can be calculated from the transmembrane pressure difference and the flux value calculated from the amount of filtered water.

DESCRIPTION OF SYMBOLS 1 ... Water treatment system, 2 ... Anoxic tank, 3 ... Aerobic tank (tank), 4 ... Membrane module, 5 ... Pressure gauge, 6 ... Treated water tank, 7 ... Chemical solution tank, 8 ... Chemical solution concentration adjustment tank, 9 ... Cleaning chemical solution discharge tank, 10 ... Membrane cleaning control device, 11 ... Stirrer, 12 ... Blower, 13, 16, 17, 18, 19 ... Pump, 14, 15 ... Switching valve, 31 ... Value acquisition unit, 32 ... Cleaning strength Determining unit 33 ... Cleaning condition determining unit 34 ... Membrane cleaning control unit, L1, L3, L4, L5, L6, L7, L8 ... Water supply path, L2 ... Return path, C1, C2, C3, C4, C5, C6 …Signal line

Claims (10)

An acquisition step of acquiring a transmembrane differential pressure value or a membrane filtration resistance value of the filtration membrane immediately after resumption of filtration after chemical filtration of the filtration membrane,
Based on the transmembrane pressure difference value or membrane filtration resistance value, a determination step for determining the cleaning strength when performing the next chemical cleaning,
A film cleaning control method comprising:   The film cleaning control method according to claim 1, further comprising a cleaning step of determining a concentration of the chemical solution used for the chemical solution cleaning based on the cleaning strength and performing the chemical solution cleaning using the chemical solution having the concentration.   The film cleaning control method according to claim 1, further comprising a cleaning step of determining a cleaning time for the chemical cleaning based on the cleaning strength and performing the chemical cleaning for the cleaning time.   The oxalic acid or citric acid is selected as the chemical solution used for the chemical cleaning in the cleaning step when the transmembrane pressure difference value or the membrane filtration resistance value exceeds a predetermined value. The film cleaning control method described.   The film cleaning control method according to any one of claims 1 to 4, wherein the cleaning strength is divided into three or more stages. A value acquisition unit for acquiring a transmembrane differential pressure value or a membrane filtration resistance value of the filtration membrane immediately after resumption of filtration after chemical filtration of the filtration membrane;
Based on the transmembrane pressure difference value or membrane filtration resistance value, a cleaning strength determination unit that determines the cleaning strength when performing the next chemical cleaning,
A membrane cleaning control device comprising:   The film cleaning control apparatus according to claim 6, further comprising a cleaning condition determining unit that determines a concentration of a chemical solution used for the chemical cleaning or a cleaning time for the chemical cleaning based on the cleaning strength. A tank for storing treated water;
A membrane provided in the tank for filtering the water to be treated;
A pressure gauge for measuring the pressure on the secondary side of the membrane;
A treated water tank for storing treated water after filtration;
A chemical tank for storing the chemical,
A chemical concentration adjusting tank that is connected to the treatment water tank and the chemical liquid tank and adjusts the concentration of the chemical liquid by mixing the chemical liquid and the treatment water;
The film cleaning control device according to claim 6 or 7,
With
The value acquisition unit of the membrane cleaning control apparatus acquires the transmembrane pressure difference value based on the pressure on the secondary side,
The film cleaning control device includes a film cleaning control unit that controls a supply amount of the chemical liquid supplied from the chemical liquid tank to the chemical liquid concentration adjustment tank or a supply time of the chemical liquid from the chemical liquid concentration adjustment tank to the film. A water treatment system further provided. A tank for storing treated water;
A membrane provided in the tank for filtering the water to be treated;
A pressure gauge for measuring the pressure on the secondary side of the membrane;
A filtered water meter that measures the amount of filtered water that is the amount of treated water filtered by the membrane;
A treated water tank for storing the treated water after filtration;
A chemical tank for storing the chemical,
A chemical concentration adjusting tank that is connected to the treatment water tank and the chemical liquid tank and adjusts the concentration of the chemical liquid by mixing the chemical liquid and the treatment water;
The film cleaning control device according to claim 6 or 7,
With
The value acquisition unit of the membrane cleaning control device acquires the membrane filtration resistance value based on the pressure on the secondary side and the amount of filtered water,
The film cleaning control device includes a film cleaning control unit that controls a supply amount of the chemical liquid supplied from the chemical liquid tank to the chemical liquid concentration adjustment tank or a supply time of the chemical liquid from the chemical liquid concentration adjustment tank to the film. A water treatment system further provided.   The water treatment system according to claim 9, wherein the membrane filtration resistance value is calculated by a value obtained by dividing a transmembrane differential pressure acquired based on the pressure on the secondary side by a power of a flux calculated from the filtered water amount.

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