JP7214576B2 - Cleaning air volume control system and cleaning air volume control device - Google Patents

Description

An embodiment of the present invention relates to a cleaning air volume control system and a cleaning air volume control device.

The sewage that has flowed through the sewage pipe is supplied to the aeration tank through a screen, a settling basin, a primary sedimentation basin, and the like. Organic substances in sewage are decomposed into carbon dioxide and water by heterotrophic bacteria, which are a type of microorganism contained in activated sludge in the aeration tank. Further, the ammonia component in the sewage is oxidized into nitrate-form nitrogen components by nitrifying bacteria (nitrite bacteria and nitrate bacteria), which are a kind of microorganisms contained in the activated sludge in the aeration tank. Heterotrophic bacteria and nitrifying bacteria proliferate by these decomposition reactions.

The treated water after organic substances and ammonia in the sewage are decomposed and removed is separated from the activated sludge by a separation membrane unit arranged in the aeration tank. Solid components in the activated sludge cannot pass through the separation membrane unit, and treated water passes through the separation membrane unit. The treated water that has passed through the separation membrane unit is discharged from the aeration tank.

As the treated water is discharged from the separation membrane unit, microorganisms contained in the activated sludge and polymer compounds such as EPS (Extracellular Polymeric Substance), which are metabolites of microorganisms, and inorganic substances, etc. enter the treated water passage of the separation membrane unit. enter. This causes gradual clogging of the separation membrane unit. In order to detect this clogging state, trans membrane pressure (TMP), which is the difference between the water pressure on the upstream side (primary side) and the water pressure on the downstream side (secondary side) of the separation membrane when the treated water is discharged. is measured.

When clogging occurs in the separation membrane unit, the transmembrane pressure difference required to obtain the same discharge flow rate of treated water gradually increases. In order to suppress clogging of the separation membrane unit, an air diffuser for cleaning the separation membrane unit with air is provided below the separation membrane unit in the aeration tank. The air diffuser supplies air to clean the membrane surface. The amount of air for cleaning the membrane supplied by the diffuser is called cleaning air volume. Conventionally, the air diffuser was often operated at a rated air volume determined for each separation membrane unit. The power consumption of the blower that supplies the cleaning air volume accounts for most of the power cost of the membrane treatment system. Therefore, it is required to reduce the amount of cleaning air.

Therefore, in order to reduce the cleaning air volume, a method of generating a control target value of transmembrane pressure difference or membrane filtration resistance and controlling the cleaning air volume in accordance with the control target is used in the membrane treatment system. The control target values are the initial value TMP ₀ of the transmembrane pressure or membrane filtration resistance, the upper limit value TMP _lim of the transmembrane pressure or membrane filtration resistance that requires chemical cleaning, the maintenance cycle L for chemical cleaning, and the clogging index k. determined based on In the control method described above, it is necessary to set the maintenance cycle L appropriately. Here, if the maintenance cycle L is set to be longer than the maintenance cycle L _m when the cleaning air volume is diffused at the rated air volume for the separation membrane unit, it is not possible to control the cleaning air volume in accordance with the control target. rice field. Also, the maintenance cycle _Lm changes according to the amount or quality of treated water. Therefore, the operator of the membrane treatment system needs to set the maintenance cycle L according to the amount or quality of treated water. The operator of the membrane treatment system appropriately sets the maintenance cycle L based on his/her experience and knowledge. However, in such a setting method based on experience and knowledge, it is difficult to set an appropriate maintenance cycle L for reasons such as the operator making a mistake in judgment or the operator's experience and knowledge being insufficient. was difficult at times.

JP 2017-18940 A

The problem to be solved by the present invention is to provide a cleaning air volume control system and a cleaning air volume control device that can more appropriately determine a maintenance cycle while reducing the cleaning air volume.

The cleaning air volume control system of the embodiment has a representative pond pressure gauge, a target value setting section, and an air volume control section. The representative pond pressure gauge is installed in a representative pond to which air is supplied at a rated air volume, and measures the transmembrane pressure difference of the representative pond separation membrane unit that filters the water to be treated flowing into the representative pond. The target value setting unit is installed in a control pond to which air is supplied at a predetermined air volume less than the rated air volume, and is a control pond separation membrane unit that filters the same water to be treated as the water to be treated that flows into the representative pond. Based on the upper limit value of the transmembrane pressure difference or the transmembrane filtration resistance, and the temporal change information of the transmembrane filtration resistance or the transmembrane pressure difference of the representative pond separation membrane unit calculated based on the transmembrane pressure difference of the representative pond separation membrane unit to set the target value of the transmembrane pressure or membrane filtration resistance of the control reservoir. The air volume control unit controls the volume of air supplied to the control pond based on the target value.

The figure which shows the sewage treatment system 10 of 1st Embodiment. 1 is a system configuration diagram of a cleaning air volume control system 1 according to a first embodiment; FIG. 2 is a functional block diagram of the cleaning air volume control system 1 of the first embodiment; FIG. The figure which shows one specific example of the change of the transmembrane pressure difference and the cleaning air volume in the representative pond of 1st Embodiment, and a control pond. A flow chart showing a specific example of cleaning air volume control of the first embodiment. FIG. 5 is a diagram showing a specific example of correcting the time difference between chemical cleaning timings in the representative pond and the first control pond in the first embodiment; FIG. 10 is a functional block diagram of a cleaning air volume control system 1a according to a second embodiment; The figure which shows the relationship between the transmembrane pressure|voltage difference of a control pond in 2nd Embodiment, and time. The figure which shows one specific example of correction of the control target of the control pond of 2nd Embodiment. FIG. 11 is a flowchart showing a specific target value acquisition process according to the second embodiment; FIG. FIG. 11 is a flow chart showing one specific process for determining whether or not the maintenance cycle of the second embodiment can be achieved; FIG.

Hereinafter, a cleaning air volume control system and a cleaning air volume control device according to embodiments will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing a sewage treatment system 10 of the first embodiment. The sewage treatment system 10 includes a screen 100 , an aeration tank 200 and a treatment tank 300 .

The screen 100 removes from the sewage that has flowed into the sewage treatment system 10 large contaminants on the order of millimeters that would damage the membrane surface of the separation membrane. Sewage is, for example, liquid containing dirt or impurities. The sewage after passing through the screen flows into the aeration tank 200 . Air is blown into the activated sludge in the aeration tank 200 . As a result, organic matter and ammonia in the sewage are oxidatively decomposed and removed by the action of microorganisms in the activated sludge. Treated water is discharged using the separation membrane unit 204 . Treated water discharged through the separation membrane unit 204 flows into the treated water tank 300 .

FIG. 2 is a system configuration diagram of the cleaning air volume control system 1 of the first embodiment. The cleaning air volume control system 1 controls the cleaning aeration of the separation membrane unit 204 provided in the aeration tank 200 . In the cleaning aeration, air is blown from the bottom of the separation membrane unit 204 to prevent clogging of the membrane. The cleaning air volume control system 1 controls the amount of blown air (hereinafter referred to as "cleaning air volume"). The cleaning air volume control system 1 in the first embodiment includes three water treatment lines.

The cleaning air volume control system 1 of the first embodiment includes a first aeration tank 200a for the first flow path 201a. 203a, a first separation membrane unit 204a, a first pressure gauge 205a, a first flow meter 206a, a first membrane cleaning blower 207a, a first cleaning airflow meter 208a, and a first air diffuser 209a. The cleaning air volume control system 1 of the first embodiment includes a second aeration tank 200b for the second flow path 201b. 203b, a second separation membrane unit 204b, a second pressure gauge 205b, a second flow meter 206b, a second membrane cleaning blower 207b, a second cleaning airflow meter 208b, and a second air diffuser 209b. The cleaning air volume control system 1 of the first embodiment includes a third aeration tank 200c for the third flow path 201c. 203c, a third separation membrane unit 204c, a third pressure gauge 205c, a third flow meter 206c, a third membrane cleaning blower 207c, a third cleaning airflow meter 208c, and a third air diffuser 209c. The cleaning air volume control system 1 of the first embodiment includes a control device 250 . The first separation membrane unit 204a is one aspect of a representative separation membrane unit. The first pressure gauge 205a is one aspect of a representative reservoir pressure gauge. The second separation membrane unit 204b and the third separation membrane unit 204c are one aspect of the control pond separation membrane unit. The second pressure gauge 205b and the third pressure gauge 205c are one aspect of control reservoir pressure gauges.

In the following description, the aeration tank 200 will be simply referred to when there is no distinction between the first to third aeration tanks. In the following description, the flow path 201 is simply referred to when there is no distinction between the first to third flow paths. In the following description, it is simply referred to as the auxiliary air diffusion blower 202 when there is no distinction between the first to third auxiliary air diffusion blowers. In the following description, it is simply referred to as the auxiliary air diffuser 203 when it is not distinguished which one of the first to third auxiliary air diffusers. In the following description, the separation membrane unit 204 is simply referred to as the separation membrane unit 204 when the distinction between the first to third separation membrane units is not made. In the following description, the pressure gauge 205 is simply referred to as the pressure gauge 205 when no distinction is made between the first to third pressure gauges. In the following description, the flowmeter 206 will be simply referred to as the flowmeter 206 when no distinction is made between the first to third flowmeters. In the following description, the membrane cleaning blower 207 is simply referred to as the membrane cleaning blower 207 unless it is distinguished which one of the first to third membrane cleaning blowers. In the following description, the cleaning air volume meter 208 is simply referred to as the cleaning air volume meter 208 when the first to third cleaning air volume meters 208 are not distinguished. In the following description, the air diffuser 209 is simply referred to as the diffuser 209 when the first to third air diffusers are not distinguished.

A water treatment system in the cleaning air volume control system 1 will be described. Wastewater to be treated flows into the aeration tank 200 through a flow path 201 . The aeration tank 200 includes a biological reaction tank for treating sewage and a separation membrane unit 204 for solid-liquid separation in the biological reaction tank. Under the separation membrane unit 204, a membrane cleaning blower 207 is provided for cleaning and aerating to prevent membrane clogging. In addition, the aeration tank 200 is provided with an auxiliary air diffusion blower 202 . Auxiliary aeration blower 202 supplies the oxygen required for biological treatment.

A flow of sewage treatment in the cleaning air volume control system 1 will be described. Sewage to be treated is allowed to flow into the aeration tank 200 . The aeration tank 200 treats incoming sewage by microorganisms and membrane filtration. A specific description will be given below. Activated sludge in which aerobic microorganisms (heterotrophic bacteria, nitrifying bacteria, etc.) are activated exists in the aeration tank 200 . The auxiliary air diffuser 202 supplies air into the auxiliary air diffuser 203 . The auxiliary air diffuser 203 supplies air to the activated sludge in the aeration tank 200 . This releases air bubbles into the activated sludge in the aeration tank 200 . Organic substances and ammonia in the sewage that has flowed into the aeration tank 200 are decomposed and removed by the action of microorganisms in the activated sludge in the aeration tank 200 .

The separation membrane unit 204 is equipment in which a plurality of separation membranes are integrated. The separation membrane unit 204 is arranged to be immersed in the sewage in the aeration tank 200 . The separation membrane unit 204 filters water to be treated such as sewage in the aeration tank 200 . The separation membrane used in the separation membrane unit 204 is, for example, a porous flat membrane having a plurality of permeation channels with an average pore size of 0.4 [μm]. The size of microorganisms contained in activated sludge ranges from about 1 [μm] (bacteria) to several hundred [μm] (protozoa, etc.). Therefore, microorganisms contained in the activated sludge cannot pass through the separation membrane unit 204, and clear treated water passes through the separation membrane unit 204. In sewage treatment, solid-liquid separation is performed by the separation membrane unit 204 by driving a suction pump (not shown), and the sewage that permeates the separation membrane unit 204 is discharged as treated water. A pressure gauge 205 and a flow meter 206 are provided on the pipe for the treated water that has permeated the separation membrane unit 204 . The pressure gauge 205 can calculate the transmembrane pressure difference of the separation membrane unit 204 based on the measured value. Pressure gauge 205 sends measurements to controller 250 . A flow meter 206 measures the flow rate of the treated water.

Membrane cleaning blower 207 supplies air to diffuser 209 . The air diffuser 209 is installed below the separation membrane unit 204 . The air diffuser 209 releases air bubbles with the supplied air. The air diffuser 209 cleans the surface of the separation membrane by applying a bubble flow to the surface of the separation membrane. This suppresses the progress of clogging of the separation membrane (hereinafter referred to as "membrane fouling"). A cleaning air flow meter 208 is provided in a pipe through which air supplied to the air diffuser 209 passes. The cleaning airflow meter 208 measures the volume of air supplied from the membrane cleaning blower 207 .

When the transmembrane pressure difference of the separation membrane becomes higher than a preset upper limit value, the separation membrane is washed with a chemical solution. Specifically, the sewage flowing into the aeration tank 200 is temporarily stopped, and the membrane filtration by the separation membrane is also stopped at the same time. Thereafter, the separation membrane unit 204 is washed by injecting a chemical such as sodium hypochlorite or oxalic acid from the downstream side (secondary side) of the separation membrane unit 204 . When the cleaning of the separation membrane unit 204 is completed, the transmembrane pressure difference of the separation membrane unit 204 recovers to near the initial value. The separation membrane unit 204 cleaned with the chemical solution starts membrane filtration again in the aeration tank 200 .

The cleaning air volume control system 1 in the first embodiment includes three aeration tanks, a first aeration tank 200a, a second aeration tank 200b and a third aeration tank 200c. The cleaning air volume control system 1 operates the first aeration tank 200a as a representative pond. The cleaning air volume control system 1 operates the second aeration tank 200b as a first control pond. The cleaning air volume control system 1 operates the third aeration tank 200c as a second control pond. The representative pond and the control pond are constructed with the same specifications. For example, the representative pond and the control pond have aeration tanks of the same capacity. For example, the separation membrane units 204 provided in the representative reservoir and the control reservoir are separation membrane units having the same specifications in terms of the number of membranes, thickness, pore size, and the like. For example, wastewater flowing into the representative pond and the control pond are treated with the same wastewater. The first membrane cleaning blower 207 a of the representative pond is operated at a rated air volume determined for each separation membrane unit 204 . On the other hand, the cleaning air volume of the second membrane cleaning blower 207b of the first control pond and the third membrane cleaning blower 207c of the second control pond is controlled by the controller 250. FIG. The cleaning air volume controlled by the control device 250 may be less than the rated air volume. Hereinafter, when it is not distinguished whether the device (for example, the second separation membrane unit 204b or the third separation membrane unit 204c) is installed in either the first control pond or the second control pond, it is simply referred to as the control pond. will be referred to as the device (for example, the separation membrane unit 204 of the control pond).

FIG. 3 is a functional block diagram of the cleaning air volume control system 1 of the first embodiment. The cleaning air volume control system 1 includes a control device 250 . The control device 250 controls the washing air volume of the first control pond and the second control pond. The control device 250 includes a processor such as a CPU (Central Processing Unit) and a memory that stores programs executed by the processor. The control device 250 realizes each function of the target value setting section 251 and the air volume control section 252 by executing the programs stored in the memory. Note that the target value setting unit 251 and the air volume control unit 252 may be hardware such as LSI (Large Scale Integration) and ASIC (Application Specific Integrated Circuit).

The target value setting unit 251 calculates the target value of the transmembrane pressure difference between the first control reservoir and the second control reservoir based on the transmembrane pressure difference of the representative reservoir. The target value setting unit 251 calculates the target value of the transmembrane pressure by, for example, calculation using the following formula (1).

Here, TMP ₀ (t) is the measured value of the transmembrane pressure of the representative pond. The transmembrane pressure is expressed in units of kPa. The target value setting unit 251 acquires the transmembrane pressure TMP ₀ (t) of the first separation membrane unit 204a from the first pressure gauge 205a. TMP _ref1 (t) is the target value of the transmembrane pressure difference of the first control reservoir. TMP _ref2 (t) is the target value of the transmembrane pressure difference of the second control reservoir. a ₁ , a ₂ , b ₁ and b ₂ are correction coefficient parameters. The correction coefficient parameter is used when the second membrane cleaning blower 207b and the third membrane cleaning blower 207c are operated under the same operating conditions and there is a predetermined difference in the transmembrane pressure values between the ponds. The correction coefficient parameter is determined by statistically processing past operating data. If there is no predetermined difference in the transmembrane pressure values between the ponds, the target value setting unit 251 may calculate the target value of the transmembrane pressure with a ₁ =a ₂ =1 and b ₁ =b ₂ =0. good.

In calculating the target value of the transmembrane pressure difference, the target value setting unit 251 may use any formula as long as it is calculated using TMP ₀ (t) of the representative pond. For example, the target value setting unit 251 may calculate the target value of TMP by calculation according to Equation (2) below.

The air volume control unit 252 controls the air volume of the first control pond and the second control pond. The air volume control unit 252 calculates the air volume according to the difference between the target value of the transmembrane pressure difference of each control pond calculated by Equation (1) or Equation (2) and the measured value of the transmembrane pressure difference of each control pond. do. The air volume control unit 252 calculates, for example, a PI (Proportional-Integral) control formula that is commonly used in process control. For example, the PI control formula is represented by Equation (3) below.

where _Kp is the proportional gain. T _i is the integration time. Both K _p and T _i are positive values. Q _air1 (t) is the washing air volume (m ³ /min) of the first washing pond. TMP ₁ (t) is the measured transmembrane pressure (kPa) of the first control reservoir. Q _air2 (t) is the washing air volume (m ³ /min) of the second washing pond. TMP ₂ (t) is the measured transmembrane pressure (kPa) of the second control pond.

The air volume control unit 252 acquires the transmembrane pressure difference TMP ₁ (t) of the second separation membrane unit 204b from the second pressure gauge 205b. Based on the formula (3), the air volume control unit 252 controls the _second membrane cleaning blower _207b to Perform control to increase the air volume. Based on the formula (3), the air volume control unit 252 controls the _second membrane cleaning blower _207b to Perform control to reduce the air volume.

The air volume control unit 252 acquires the transmembrane pressure difference TMP ₂ (t) of the third separation membrane unit 204c from the third pressure gauge 205c. Based on the formula (3), the air volume control unit 252 controls the _third membrane cleaning blower _207c to Perform control to increase the air volume. Based on the formula (3), the air volume control unit 252 controls the _third membrane cleaning blower _207c to Perform control to reduce the air volume.

FIG. 4 is a diagram showing a specific example of changes in the transmembrane pressure difference and the cleaning air volume in the representative pond and the control pond of the first embodiment. As shown in FIG. 4, the washing air volume of the representative pond is kept constant at the rated air volume _Q0 . The air volume control unit 252 controls the cleaning air volume based on the formula (3) so that the increase in the transmembrane pressure difference in the representative pond and the transmembrane pressure difference in the control pond are approximately equal. The control of the cleaning air volume is started after chemical cleaning is performed. Therefore, the air volume control unit 252 can reduce the air volume of the second membrane cleaning blower 207b and the third membrane cleaning blower 207c, and can reduce the power cost of the membrane cleaning blower 207 of the control pond. As shown in FIG. 4, the cleaning air volume control system 1 achieves an air volume reduction effect by starting the cleaning air volume in the control pond at the start of control at a smaller air volume than the cleaning air volume (rated air volume) in the representative pond. easier.

When the transmembrane pressure difference in either the representative pond or the control pond becomes equal to or higher than a predetermined pressure, the cleaning air volume control system 1 stops the membrane filtration being performed in the representative pond and the control pond. The separation membrane unit 204 is washed with a chemical solution after membrane filtration is stopped. The transmembrane pressure difference of the separation membrane unit 204 that has been washed with the chemical drops to near the initial value as shown in FIG. The cleaning air volume control system 1 starts the membrane filtration operation and controls the cleaning air volume again. The cleaning air volume control system 1 reduces the cleaning air volume by repeating the above operation.

FIG. 5 is a flow chart showing a specific example of cleaning air volume control according to the first embodiment. In this flow chart, the i-th control pond represents all the control ponds controlled by the cleaning air volume control system 1 . For example, when the cleaning air volume control system 1 controls the first to Nth control ponds, the i-th control pond refers to the N control ponds. In this embodiment, N=2 because the cleaning air volume control system 1 controls the first control pond and the second control pond. In each step of this flowchart, processing is performed for each of the first control reservoir and the second control reservoir. The target value setting unit 251 acquires the transmembrane pressure difference of the first separation membrane unit 204a provided in the representative pond from the first pressure gauge 205a (step S101). The target value setting unit 251 sets the target value of the transmembrane pressure difference of the i-th control reservoir based on the transmembrane pressure difference (step S102). The target value setting unit 251 calculates the target value of the transmembrane pressure by solving a predetermined formula such as formula (1) or formula (2).

The air volume control unit 252 acquires the transmembrane pressure difference of the separation membrane unit provided in the i-th control pond from the pressure gauge. Specifically, the air volume control unit 252 acquires the transmembrane pressure difference of the second separation membrane unit 204b provided in the first control pond from the second pressure gauge 205b. The air volume control unit 252 acquires the transmembrane pressure difference of the third separation membrane unit 204c provided in the second control reservoir from the third pressure gauge 205c (step S103). The air volume control unit 252 controls the cleaning air volume of the i-th control pond based on the target value of the transmembrane pressure difference and the acquired transmembrane pressure difference of the control pond (step S104). Specifically, when the measured value of the transmembrane pressure difference in the first control reservoir is higher than the target value of the transmembrane pressure difference in the first control reservoir, the air volume control unit 252 uses the second Control is performed to increase the air volume of the membrane cleaning blower 207b. When the measured value of the transmembrane pressure difference in the first control pond is lower than the target value of the transmembrane pressure difference in the first control pond, the air volume control unit 252 operates the second membrane cleaning blower 207b based on the formula (3). Perform control to reduce the air volume. The air volume control unit 252 performs similar control for the second control pond.

The target value setting unit 251 or the air volume control unit 252 determines whether or not the obtained transmembrane pressure difference of the representative pond or the i-th control pond is equal to or higher than a predetermined pressure (step S105). The target value setting unit 251 or the air volume control unit 252 terminates the process when the acquired transmembrane pressure of the representative reservoir or the i-th control reservoir is equal to or higher than a predetermined pressure (step S105: YES). When the process is finished, the cleaning air volume control system 1 stops membrane filtration. Chemical cleaning is performed after membrane filtration is stopped. If the acquired transmembrane pressure difference of the representative reservoir or the i-th control reservoir is less than the predetermined pressure (step S105: NO), the process transitions to step S101.

In the cleaning air volume control system 1 configured as described above, the target value setting unit 251 calculates the target value of the transmembrane pressure difference of each control pond based on the transmembrane pressure difference of the representative pond. The air volume control unit 252 controls the cleaning air volume of the control pond based on the transmembrane pressure of the control pond and the calculated target value. Specifically, the air volume control unit 252 performs control to increase the air volume when the measured value of the transmembrane pressure difference in the control reservoir is higher than the target value of the transmembrane pressure difference in the control reservoir. The air volume control unit 252 performs control to decrease the air volume when the measured value of the transmembrane pressure difference in the control reservoir is lower than the target value of the transmembrane pressure difference in the control reservoir. Therefore, the cleaning air volume control system 1 can reduce the cleaning air volume of the control pond while securing the chemical cleaning period equivalent to that of the representative pond without setting the maintenance cycle L.

Formulas (1) and (2) described in the first embodiment are formulas when the timing of control start or chemical cleaning is the same for the representative reservoir and the control reservoir. However, the representative pond and the control pond may have different timings of control start or chemical cleaning. Specifically, the target value setting unit 251, when the timing of control start or chemical cleaning of the representative pond and the control pond is different, based on the following formula (4) or (5), the membrane of the control pond A target value for the differential pressure may be calculated.

Here, T1 represents the time difference between the chemical cleaning timing of the representative reservoir and the chemical cleaning timing of the _first control reservoir. T2 represents the time difference between the chemical cleaning timing of the representative pond and the chemical cleaning timing of the _second control pond.

FIG. 6 is a diagram showing a specific example of correcting the time difference between chemical cleaning timings in the representative pond and the first control pond in the first embodiment. According to FIG. 6, in the _first control reservoir, the transmembrane pressure has decreased after T1 has elapsed from the start of control. Therefore, it can be seen that the cleaning of the first control pond is carried out with _a delay of T1 from the timing of chemical cleaning of the representative pond. Therefore, when calculating the target value of the transmembrane pressure difference in the first control reservoir, the target value setting unit 251 shifts by time T ₁ based on the formula (4) or (5) and corrects it. to generate the target value.

In the first embodiment, an example in which there are two control ponds such as the first control pond and the second control pond was shown, but there may be any number of control ponds as long as they are one or more. Also, the representative pond is not limited to a specific aeration tank 200 . For example, the representative pond and the control pond may be configured to be changed every predetermined period. With this configuration, the devices such as the separation membrane unit 204 or the membrane cleaning blower 207 installed in the representative pond always operate at the rated air volume, so that they can be discharged earlier than the devices installed in the other control ponds. deterioration can be prevented.

In the first embodiment, the transmembrane pressure and the target value of the transmembrane pressure used in Equations (1) to (5) may be the transmembrane filtration resistance. The membrane filtration resistance is a value (=TMP(t)/J(t) ^α ) obtained by dividing the transmembrane pressure by the power of the flux. Here, the flux J(t) (m/day) is a value obtained by dividing the throughput per hour (m ³ /day) of the separation membrane by the membrane area (m ² ) of the separation membrane. α is a power correction coefficient. By configuring in this way, it is possible to control the cleaning air volume even when the operating flux differs between the representative pond and the control pond.

(Second embodiment)
Next, the control device 250a in the second embodiment will be described. FIG. 7 is a functional block diagram of the cleaning air volume control system 1a of the second embodiment. The control device 250a in the second embodiment includes a target value setting unit 251a instead of the target value setting unit 251, an air volume control unit 252a instead of the air volume control unit 252, a predicted value acquisition unit 253, an input unit 260 and Although it differs from the first embodiment in that a display unit 270 is further provided, the other configurations are the same. Differences from the first embodiment will be described below. Note that the control device 250a can perform the same processing for the first control pond and the second control pond. Therefore, in the following description, the first control pond and the second control pond will not be distinguished, and the explanation will be made simply as the control pond.

The input unit 260 is configured using an input device such as a touch panel, mouse, and keyboard. The input unit 260 may be an interface for connecting an input device to the control device 250a. In this case, the input unit 260 generates input data (for example, each value such as the upper limit value of the blockage index, maintenance cycle, and transmembrane pressure input to the control device 250a) from the input signal input by the input device. and input to the control device 250a.

The display unit 270 is an output device such as a CRT (Cathode Ray Tube) display, a liquid crystal display, an organic EL (Electro Luminescence) display, or the like. The display unit 270 may be an interface for connecting an output device to the control device 250a. In this case, the display unit 270 generates a video signal from the video data and outputs the video signal to the video output device connected thereto.

Processing of the target value setting unit 251a will be described. The target value setting unit 251a calculates a target value TMPref(t) of the transmembrane pressure difference TMP(t) of the separation membrane unit 204 of the control pond. Specifically, the target value setting unit 251a solves the differential equation represented by the following formula (6) to obtain the target value TMPref(t) of the transmembrane pressure difference TMP(t) of the separation membrane unit 204 of the control pond. ) as a function of t. Note that t represents time. The transmembrane pressure TMP(t) is measured by the pressure gauge 205 of the control reservoir.

where k represents the occlusion index. The clogging index is a parameter representing the degree of clogging of the separation membrane unit 204 of the control pond. The occlusion index k is a positive value. When k=1, the solution of equation (6) is an exponentially increasing function of the transmembrane pressure TMP(t). When k>1, the solution of equation (6) is a function in which the value of the transmembrane pressure TMP(t) diverges infinitely in a certain finite time. The clogging index k may be set to any value of k=1, 1.5 or 2 according to the degree of clogging of the separation membrane unit 204 of the control pond. For example, k=1 for intermediate occlusion, k=1.5 for standard occlusion, and k=2 for complete occlusion. The occlusion index k is input by the user via the input unit 260 . The user may be any person who operates the control device 250a who operates the cleaning air volume control system 1, monitors membrane filtration, or the like.

When k=1, the target value setting unit 251a calculates the parameter A based on the following formula (7) and substitutes it into the formula (6).

Here, TMP ₀ is the initial value of the transmembrane pressure TMP(t). The initial value TMP ₀ is measured by the pressure gauge 205 of the control pond. The initial value represents the transmembrane pressure difference after chemical cleaning of the separation membrane unit 204 of the control pond. L is the tentatively determined maintenance cycle. The maintenance cycle L is input by the user via the input unit 260 . The maintenance cycle L is one aspect of the first cycle. TMP _lim is the upper limit of the transmembrane pressure TMP(t). When the transmembrane pressure difference reaches TMP _lim , the separation membrane unit 204 is washed with a chemical solution. TMP _lim is input by the user via the input unit 260 .

When a value other than 1 is set as k, the target value setting unit 251a calculates the parameter A based on the following formula (8). Here, the blockage index k, the maintenance period L, and the upper limit value TMP _lim of the transmembrane pressure are input by the user via the input unit 260 .

In the above formulas (6) to (8), the input blockage index k, maintenance cycle L, and upper limit value TMP _lim of the transmembrane pressure difference may be common to each control reservoir. , a different value may be input for each control pond.

FIG. 8 is a diagram showing the relationship between the transmembrane pressure of the control reservoir and time in the second embodiment. As shown in FIG. 8, the initial value TMP ₀ is the transmembrane pressure difference at timing T ₀ immediately after the separation membrane unit 204 in the control pond is cleaned with the chemical solution. A maintenance cycle L is a cycle for performing maintenance (cleaning with a chemical solution) on the separation membrane unit 204 . Specifically, the maintenance cycle L is the time from the timing _T0 immediately after the separation membrane unit 204 is cleaned with the chemical solution to the next chemical solution cleaning timing TMP _lim . The maintenance cycle L is set to 30 days, for example. The upper limit TMP _lim is set to 20 [kPa], for example.

The pressure gauge 205 of the control reservoir measures the initial value TMP ₀ of the transmembrane pressure difference at the timing T ₀ when the membrane filtration is restarted after the separation membrane unit 204 is washed with the chemical solution. The control pond pressure gauge 205 transmits the measured initial value TMP ₀ to the target value setting unit 251a of the control device 250a. On the other hand, the user uses the input unit 260 such as a mouse and keyboard to input the blockage index k, the maintenance cycle L, and the upper limit value TMP _lim . The input unit 260 transmits the input blockage index k, maintenance cycle L, and upper limit value TMP _lim to the target value setting unit 251a of the control device 250a.

Returning to FIG. 7, the description of the target value setting unit 251a is continued. The target value setting unit 251a determines whether or not the maintenance cycle L can be achieved based on the operation information of the representative pond at _each determination calculation cycle t1. Achievable means that the period from the timing when the chemical cleaning is performed to the timing when the next chemical cleaning is performed is L. If it is achievable, the next chemical cleaning is performed when the period L has elapsed from the timing at which the chemical cleaning was performed. _An arbitrary value is set in advance for the determination calculation period t1. The determination calculation cycle t1 may be, for example, _one day, or may be about once every several hours to several days. The target value setting unit 251a determines whether or not L can be achieved using different means according to the value of the clogging index k.

A case where the occlusion index is k=1 will be described. The target value setting unit 251a calculates the parameter _A0 of the representative pond based on the following formula (9). Expression (9) represents the amount of change in the transmembrane pressure of the representative pond. The amount of change is one aspect of time-dependent change information. Here, TMP ₀ ′ represents the initial value of the transmembrane pressure of the representative pond. The initial value TMP ₀ ′ is measured by the first pressure gauge 205a of the representative pond. TMP'(T) represents the current value of the transmembrane pressure of the representative pond. The current value TMP'(T) of the transmembrane pressure difference is measured by the first pressure gauge 205a of the representative reservoir. T represents the elapsed time from obtaining the initial value TMP ₀ ′ to obtaining the current value TMP′(T).

The target value setting unit 251a determines the validity of the maintenance cycle L set for the control pond based on the calculated _A0 . The target value setting unit 251a determines that an achievable maintenance cycle L is set for the control pond when the following formula (10) holds. The target value setting unit 251a does not correct L when the maintenance cycle L can be achieved.

The target value setting unit 251a determines that an unattainable maintenance cycle L is set for the control pond when the following formula (11) holds (formula (10) does not hold). The target value setting unit 251a corrects L when the maintenance cycle L cannot be achieved. Specifically, the target value setting unit 251a changes the maintenance cycle L set for the control pond to L' represented by the following formula (12). Here, B in Expression (12) is a constant parameter that takes a defined positive value. L′ represents the timing for cleaning the separation membrane unit 204 .

L' calculated by the target value setting unit 251a is a value smaller than the right side of the equation (11), as represented by the following equation (13). The following formula (14) is a formula obtained by substituting L' calculated by the target value setting unit 251a for L in formula (7). The target value setting unit 251a calculates A' based on Equation (14) expressed by substituting L' for L in Equation (7). The target value setting unit 251a calculates the target value TMP _ref (t) of the transmembrane pressure difference of the control reservoir by substituting A in Equation (6) for the calculated A′.

Next, the case where the value of the occlusion index k is not 1 will be described. When the value of the clogging index _k is not 1, the target value setting unit 251a calculates the representative pond parameter A0 based on Equation (15).

The target value setting unit 251a determines the validity of the maintenance cycle L set for the control pond based on the calculated _A0 . The target value setting unit 251a determines that an achievable maintenance cycle L is set for the control pond when the following formula (16) holds. The target value setting unit 251a does not correct L when the maintenance cycle L can be achieved.

The target value setting unit 251a determines that an unattainable maintenance cycle L is set for the control pond when the following formula (17) holds (formula (16) does not hold). The target value setting unit 251a corrects L when the maintenance cycle L cannot be achieved. Specifically, the target value setting unit 251a replaces the maintenance cycle L set for the control pond with L' represented by the following formula (18). Here, B in Expression (18) is a constant parameter that takes a defined positive value.

The following formula (19) is a formula obtained by substituting L' calculated by the target value setting unit 251a for L in formula (8). The target value setting unit 251a calculates A' based on Equation (19) in which L' is substituted for L in Equation (8). The target value setting unit 251a calculates the target value TMP _ref (t) of the transmembrane pressure difference of the control reservoir by replacing A in Equation (6) with the calculated A′.

FIG. 9 is a diagram showing a specific example of correction of the control target of the control pond according to the second embodiment. As shown in FIG. 9, the target value setting unit _251a calculates A0 based on the curve of the measured value of the transmembrane pressure difference of the representative pond. The target value setting unit 251a determines whether or not the maintenance cycle L set for the control reservoir can be achieved based on information on the transmembrane pressure difference of the representative reservoir. When the target value setting unit 251a determines that the maintenance cycle L cannot be achieved, the target value setting unit 251a corrects the control target so that the maintenance cycle L becomes L'.

Returning to FIG. 7, the processing of the predicted value acquisition unit 253 will be described. The predicted value acquiring unit 253 calculates the predicted value TMPhat(t) of the transmembrane pressure difference TMP(t) of the separation membrane unit 204 of the control pond as a function of t by solving the following formula (20). The predicted value is a value obtained by predicting the value of the transmembrane pressure difference or the membrane filtration resistance after the measurement of the transmembrane pressure difference of the separation membrane unit 204 of the control pond. The predicted value is used for the cleaning air volume control of the first control pond or the second control pond, but the prediction of the representative pond may also be carried out in the same manner. The representative pond is operated with a constant rated air volume.

Here, the flux J(t) is the amount of treated water that passes through the separation membrane unit 204 per unit area at time t. Specifically, the predicted value acquisition unit 253 calculates the flux J(t) by dividing the flow rate measured by the flow meter 206 of the control pond by the membrane area of the separation membrane unit 204 of the control pond.

The predicted value acquisition unit 253 eliminates R(t) from the following formulas (21) and (22), and defines the coefficient of TMP(t) ^k as a parameter A _m (t), thereby obtaining formula (20 ). where μ represents the viscosity coefficient. J(t) represents flux. R(t) represents membrane filtration resistance. k represents the occlusion index (k=1, 1.5 or 2). f(X) represents a factor that increases the membrane filtration resistance. Normally, f(X) is proportional to flux J(t) or water quality concentration c×flux J(t). The transmembrane pressure TMP(t), the flux J(t) and the membrane filtration resistance R(t) are measured values related to clogging of the separation membrane unit 204 of the control pond.

When the value of the flux J(t) is controlled to be constant, the above formula (21) is represented by the following formula (23). Equation (23) is an equation obtained by replacing parameter A in equation (6) with parameter A _m (t).

Parameters A _m (t) included in the prediction models of formulas (20) and (23) are, as shown in formula (24) below, coefficient a ₁ , coefficient a ₂ , flux X ₁ (t) and It is calculated based on the air volume X ₂ (t). Here, the predicted value acquiring unit 253 uses the calculated flux J(t) as the flux X ₁ (t). In addition, the predicted value acquiring unit 253 uses the air volume received from the cleaning air volume meter 208 of the control pond as the air volume X ₂ (t).

In Equation (24), X ₂ (t) is the volume of air supplied from the air diffuser 209 of the control pond, but X ₂ (t) is the air volume supplied from the air diffuser 209 of the control pond. It is good also as air magnification of . The air ratio represents the ratio of the amount of air sent to the aeration tank 200 to the amount of wastewater flowing into the aeration tank 200 of the control pond. Note that the predicted value acquiring unit 253 uses the least squares method, the partial least squares method, the total least squares method, the generalized least squares method, the regularized least squares method, and the support vector regression method based on the measured values related to the clogging of the separation membrane. Alternatively, any one or more of adaptive vector regression may be used to calculate the coefficients.

_The predicted value obtaining unit 253 calculates the parameter Am _{( t} ) is calculated. The predicted value acquisition unit 253 solves the differential equation of Expression (20) using the calculated parameter A _m (t), the flux J (t), and the clogging index k, so that the membrane of the separation membrane unit 204 of the control pond A predicted value TMP _hat (t) of the differential pressure TMP(t) is calculated.

Next, processing of the air volume control unit 252a will be described. Based on the target value TMP _ref (t) calculated by the target value setting unit 251a and the predicted value TMP _hat (t) calculated by the predicted value acquisition unit 253, the air volume control unit 252a performs membrane cleaning of the control pond. The air volume of the blower 207 is controlled.

The air volume control unit 252a calculates the difference E(t) between the target value TMP _ref (t) and the predicted value TMP _hat (t) based on the following formula (25).

The air volume control unit 252a performs PI control on the membrane cleaning blower 207 of the control pond using the calculated difference E(t). Specifically, the air volume control unit 252a calculates the operation amount u(t) of the membrane cleaning blower 207 of the control pond based on Expression (26). _Kp is the proportional gain in PI control. K _i is the integral gain in PI control. T _now is the current time. _Tp is the elapsed time from the current time T _now . _Tp may be set to one day (24 hours), for example.

The air volume control unit 252a causes the display unit 270 to display the maintenance cycle L. FIG. The air volume control unit 252a may display the number of days until the maintenance cycle L is reached. In this case, the air volume control unit 252a calculates the number of days until the maintenance cycle L is reached by subtracting the current time T _now from the maintenance cycle L.

As shown in FIG. 8, the target value TMP _ref (t) of the transmembrane pressure is indicated by a thick solid line. The measured transmembrane pressure difference TMP _act (t) is indicated by a thin solid line. The predicted value TMP _hat (t) of the transmembrane pressure after the current time T _now is indicated by a dashed line.

As shown in FIG. 8, at the current time T _now , the transmembrane pressure target value TMP _ref (t) and the transmembrane pressure difference actual measurement value TMP _act (t) are equal. However, FIG. 8 shows that a difference E(t) occurs between the target value TMP ₁ and the predicted value TMP ₂ at the time T _next after the lapse of _Tp from the current time T _now . Therefore, the air volume control unit 252a calculates the operation amount u(t) of the membrane cleaning blower 207 based on the difference E(t) between the target value TMP _ref (t) and the predicted value TMP _hat (t). The air volume control unit 252a controls the membrane cleaning blower 207 using two parameters (proportional gain K _p and integral gain K _i ), so that parameter adjustment can be easily and simply performed.

In the second embodiment, the air volume control unit 252a performs PI control, but may be configured to perform PID (Proportional-Integral-Derivative) control. In this case, the air volume control unit 252a calculates the operation amount u(t) of the membrane cleaning blower 207 of the control pond in consideration of the differential value of the difference E(t). Therefore, the air volume control section 252a can perform more stable control. In addition, the air volume control unit 252a performs rule-based control or extreme value control instead of PI control or PID control, so that air is supplied from the air diffuser 209 of the control pond to the separation membrane unit 204 of the control pond. It may be configured to control the air flow rate.

FIG. 10 is a flowchart showing a specific target value acquisition process according to the second embodiment. This flowchart is executed by the target value setting section 251a when the filtration operation is restarted after the separation membrane unit 204 has been washed with the chemical solution. The target value setting unit 251a acquires the initial value TMP ₀ of the transmembrane pressure from the pressure gauge 205 of the control reservoir (step S201). The target value setting unit 251a determines whether or not the user has input the blockage index k, the upper limit TMP _lim , and the maintenance cycle L (step S202). The user inputs these values using input unit 260 .

If the user has not input the blockage index k, the upper limit TMP _lim , and the maintenance cycle L (step S202: NO), the process proceeds to step S202. When the user inputs the blockage index k, the upper limit value TMP _lim , and the maintenance cycle L (step S202: YES), the target value setting unit 251a calculates the parameter A based on Equation (7) or Equation (8). (Step S203). The target value setting unit 251a calculates the target value TMP _ref (t) of the transmembrane pressure difference of the control reservoir by solving the differential equation of Expression (6) (step S204).

_The target value setting unit 251a determines whether or not the determination calculation cycle t1 has passed (step S205). When the determination calculation period _t1 has not passed (step S205: NO), the target value setting unit 251a transitions to step S205. When the determination calculation cycle _t1 has passed (step S205: YES), the target value setting unit 251a determines whether or not the maintenance cycle L can be achieved (step S206). Note that the process of determining whether or not it is achievable will be described in detail with reference to FIG. 11 . When L can be achieved (step S206: YES), the target value setting unit 251a transitions to step S205.

When the target value setting unit 251a cannot achieve L (step S206: NO), the target value setting unit 251a corrects the maintenance period L to L' (step S207). Calculation of L' will be described in detail with reference to FIG. The target value setting unit 251a corrects A in Equation (6) to A' (step S208). Calculation of A' will be described in detail with reference to FIG. The target value setting unit 251a calculates the TMP target value TMP _ref (t) of the control pond (step S209). The target value setting unit 251a determines whether or not the set transmembrane pressure is equal to or higher than a predetermined pressure (step S210). When the set transmembrane pressure is equal to or higher than the predetermined pressure (step S210: YES), the target value setting unit 251a ends the process. When the process is finished, the cleaning air volume control system 1 stops membrane filtration. Chemical cleaning is performed after membrane filtration is stopped. When the set transmembrane pressure is less than the predetermined pressure (step S210: NO), the target value setting unit 251a transitions to step S204.

FIG. 11 is a flow chart showing one specific process for determining whether or not the maintenance cycle of the second embodiment can be achieved. This flowchart is executed by the target value setting unit 251a when determining whether or not the maintenance cycle L can be achieved when the determination calculation cycle _t1 has passed. The target value setting unit _251a calculates the parameter A0 of the representative pond (step S301). Here, when the clogging index is k ₌ 1, the target value setting unit 251a calculates the parameter A0 of the representative pond based on Equation (9). When the clogging index _k is other than 1, the target value setting unit 251a calculates the representative pond parameter A0 based on Equation (15).

The target value setting unit 251a determines whether or not the maintenance cycle L set for the control pond can be achieved based on the calculated _A0 (step S302). Specifically, when the clogging index is k=1, the target value setting unit 251a determines that the maintenance cycle L can be achieved for the control pond when the formula (10) holds. When the clogging index k is other than 1, the target value setting unit 251a determines that the maintenance cycle L can be achieved for the control pond if the formula (16) holds.

If the maintenance cycle L can be achieved (step S302: YES), the target value setting unit 251a ends the process. When the maintenance period L cannot be achieved (step S302: NO), the target value setting unit 251a calculates L' (step S303). Specifically, when the blockage index is k=1, the target value setting unit 251a calculates L' based on Equation (12). When the clogging index k is other than 1, the target value setting unit 251a calculates L' based on Equation (18). The target value setting unit 251a calculates A' (step S304). Specifically, when the blockage index is k=1, the target value setting unit 251a calculates L' based on Equation (14). When the clogging index k is other than 1, the target value setting unit 251a calculates L' based on Equation (19).

The cleaning air volume control system 1a performs the processing described above for each of the first control pond and the second control pond. That is, the air volume control of the second membrane cleaning blower 207b is performed based on the target value of the first control pond and the predicted value of the first control pond. The air volume control of the third membrane cleaning blower 207c is performed based on the target value of the second control pond and the predicted value of the second control pond.

In the cleaning air volume control system 1a configured as described above, the target value setting unit 251a determines whether or not the maintenance cycle L input via the input unit 260 can be achieved. The target value setting unit 251a corrects the maintenance cycle L to L′ when the maintenance cycle L is not achievable. By configuring in this way, the maintenance cycle can be determined more accurately. Also, the target value setting unit 251a can more appropriately calculate the target value TMP _ref (t) of the control pond. Based on the difference E(t) between the target value TMP _ref (t) and the predicted value TMP _hat (t) of the control pond, the air volume control unit 252a blows air from the air diffuser 209 of the control pond toward the separation membrane unit 204. Controls the amount of air supplied. Therefore, the difference between the actual transmembrane pressure difference of the separation membrane unit 204 and the target value TMP _ref (t) can be reduced, and the amount of cleaning air supplied to the separation membrane unit 204 of the control pond can be reduced. be possible.

In the second embodiment, an example in which there are two control ponds, such as the first control pond and the second control pond, is shown, but the number of control ponds may be one or more. Also, the representative pond is not limited to a specific aeration tank 200 . For example, the representative pond and the control pond may be configured to be changed every predetermined period. By configuring in this way, it is possible to prevent deterioration of a specific device such as the separation membrane unit 204 or the membrane cleaning blower 207 .

In the cleaning air volume control system 1a in the second embodiment, the transmembrane pressure difference and the transmembrane pressure target value are divided by the transmembrane pressure difference by the power of the flux (=TMP(t)/J( t) α) may be used to control the cleaning air volume. With this configuration, the cleaning air volume control system 1a can correct the maintenance period L even if the operating flux differs between the representative pond and the control pond.

The information X used for TMP prediction is not limited to flux, cleaning air volume, or air magnification. For example, the cleaning air volume control system 1a in the second embodiment includes, as information X, water temperature, MLSS concentration, auxiliary aeration amount, coagulant injection amount, circulation pump flow rate, return pump flow rate, dissolved oxygen concentration in sewage or treated water. , ORP, pH, EEM, absorbance, BOD, COD, TOC, ammonia concentration, nitric acid concentration, phosphoric acid concentration, total nitrogen concentration, total phosphorus concentration, soluble COD concentration, soluble BOD concentration and the above variables On the other hand, any information may be added and used as long as it is the operating data of the MBR that can affect the fouling of the membrane, such as a synthetic variable obtained by performing the four arithmetic operations. The variables to be employed may be set by predetermining the correlation between the operating data of TMP and MBR.

The control device 250 may be implemented using a plurality of information processing devices communicably connected via a network. In this case, each functional unit included in the control device may be distributed and implemented in a plurality of information processing devices. For example, the target value setting unit 251 and the air volume control unit 252 may be implemented in different information processing devices.

While several embodiments of the invention have been described, these embodiments have been 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 modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 1... Cleaning air volume control system 10... Sewage treatment system 100... Screen 200... Aeration tank 201... Flow path 202... Auxiliary air diffusion blower 203... Auxiliary air diffuser 204... Separation membrane unit 205... Pressure meter 206 flow meter 207 membrane cleaning blower 208 cleaning air flow meter 209 air diffuser 250 control device 251 target value setting unit 252 air volume control unit 253 predicted value acquisition unit 260... Input part, 300... Treated water tank

Claims (15)

a representative pond pressure gauge installed in a representative pond to which air is supplied at a rated air volume and measuring the transmembrane pressure difference of a representative pond separation membrane unit that filters the water to be treated flowing into the representative pond;
Membrane differential pressure or membrane filtration of a control pond separation membrane unit that is installed in a control pond to which air is supplied at a predetermined air volume less than the rated air volume and filters the same water to be treated as the water to be treated that flows into the representative pond The control pond separation membrane based on the upper limit value of the resistance and the membrane filtration resistance calculated based on the transmembrane pressure difference of the representative pond separation membrane unit or the temporal change information of the transmembrane pressure difference of the representative pond separation membrane unit a target value setting unit that sets a target value for the transmembrane pressure or membrane filtration resistance of the unit;
an air volume control unit that controls the volume of air supplied to the control pond based on the target value;
with
The representative pond and the control pond are configured with the same specifications,
The representative pond separation membrane unit and the control pond separation membrane unit have the same specifications,
The cleaning air volume control system , wherein the water to be treated flowing into the representative pond and the control pond is the same water to be treated . The target value setting unit sets the target value setting unit for the membrane in the elapsed time from the time when the initial value representing the transmembrane pressure difference immediately after the chemical cleaning of the representative pond separation membrane unit is performed to the time when the current transmembrane pressure difference is obtained. Calculating a period representing the timing of chemical cleaning based on information on changes in differential pressure or membrane filtration resistance over time;
The cleaning air volume control system according to claim 1. The target value setting unit sets the transmembrane pressure difference of the control pond separation membrane unit based on the initial value of the transmembrane pressure difference of the control pond separation membrane unit , which represents the transmembrane pressure difference immediately after the chemical cleaning of the control pond separation membrane unit. Set the target value of pressure or membrane filtration resistance,
a control pond pressure gauge that measures the membrane differential pressure of the control pond separation membrane unit,
The air volume control unit is calculated based on the target value set by the target value setting unit and the membrane differential pressure of the control pond separation membrane unit acquired by the control pond pressure gauge or the information of the control pond pressure gauge. and a membrane filtration resistance that controls the cleaning air volume of the control pond separation membrane unit supplied by an air diffuser provided in the control pond,
3. The cleaning air volume control system of claim 2, further comprising: The target value setting unit corrects the time difference between the chemical cleaning performed on the representative pond separation membrane unit and the chemical cleaning performed on the control pond separation membrane unit. setting a target value for the transmembrane pressure or the membrane filtration resistance;
The cleaning air volume control system according to claim 3. The target value setting unit calculates the target value based on the transmembrane pressure, the upper limit value, and the period.
The cleaning air volume control system according to claim 3 or 4. Predicted value acquisition unit for acquiring a predicted value of the transmembrane pressure difference or the membrane filtration resistance after the transmembrane pressure difference of the control pond separation membrane unit is measured, based on the measured value related to the clogging of the control pond separation membrane unit. and further comprising
The air volume control unit controls the control pond separation membrane supplied from the air diffuser to the control pond separation membrane unit based on the target value and the predicted value acquired by the predicted value acquisition unit. control the washing air volume of the unit,
The cleaning air volume control system according to any one of claims 3 to 5. The predicted value acquisition unit calculates the predicted value based on a measured value related to clogging of the control pond separation membrane unit and a flux of treated water filtered by the control pond separation membrane unit.
The cleaning air volume control system according to claim 6. The measured values related to the clogging of the control pond separation membrane unit include the flux and the air volume or air ratio of the air supplied from the air diffuser toward the control pond separation membrane unit,
The cleaning air volume control system according to claim 7 . Measured values related to clogging of the control pond separation membrane unit are water temperature, MLSS concentration, auxiliary aeration amount, coagulant injection amount, circulation pump flow rate, return pump flow rate, the water to be treated or the treated water, or the inside of the biological reaction tank Variables representing dissolved oxygen concentration, ORP, pH, EEM, absorbance, BOD, COD, TOC, ammonia concentration, nitric acid concentration, phosphoric acid concentration, total nitrogen concentration, total phosphorus concentration, soluble COD concentration, and soluble BOD concentration and at least one of the composite variables obtained by subjecting these variables to arithmetic operations,
The cleaning air volume control system according to claim 7 or 8 . The predicted value acquisition unit uses a least squares method, a partial least squares method, a total least squares method, a generalized least squares method, a regularized least squares method, a support calculating the predicted value using any one or more of vector regression and adaptive vector regression;
The cleaning air volume control system according to any one of claims 7 to 9 . The air volume control unit performs any one of PI control, PID control, rule-based control, or extreme value control based on the difference between the target value and the predicted value, thereby Control the volume of air supplied to the separation membrane unit,
The cleaning air volume control system according to any one of claims 6 to 10 . The target value setting unit divides the transmembrane pressure difference of the representative pond separation membrane unit measured by the representative pond pressure gauge by the power of the flux, and multiplies the value obtained by dividing the membrane filtration resistance of the representative pond separation membrane unit by a constant. calculated in the form of
Calculate the membrane filtration resistance of the control pond separation membrane unit by multiplying the value obtained by dividing the transmembrane pressure difference of the control pond separation membrane unit measured by the control pond pressure gauge by the power of the flux and multiplying it by a constant;
The cleaning air volume control system according to any one of claims 3 to 10 . The representative pond and the control pond are changed every predetermined period,
The cleaning air volume control system according to any one of claims 2 to 12 . further comprising a display unit that displays at least one of the period or a period until the current transmembrane pressure difference of the representative pond separation membrane unit reaches the period,
The cleaning air volume control system according to any one of claims 2 to 13 . a representative pond pressure gauge installed in a representative pond to which air is supplied at a rated air volume and measuring the transmembrane pressure difference of a representative pond separation membrane unit that filters the water to be treated flowing into the representative pond;
Membrane differential pressure or membrane filtration of a control pond separation membrane unit that is installed in a control pond to which air is supplied at a predetermined air volume less than the rated air volume and filters the same water to be treated as the water to be treated that flows into the representative pond The control pond separation membrane based on the upper limit value of the resistance and the membrane filtration resistance calculated based on the transmembrane pressure difference of the representative pond separation membrane unit or the temporal change information of the transmembrane pressure difference of the representative pond separation membrane unit a target value setting unit that sets a target value for the transmembrane pressure or membrane filtration resistance of the unit;
an air volume control unit that controls the volume of air supplied to the control pond based on the target value;
with
The representative pond and the control pond are configured with the same specifications,
The representative pond separation membrane unit and the control pond separation membrane unit have the same specifications,
The cleaning air volume control device , wherein the water to be treated flowing into the representative pond and the control pond is the same water to be treated .

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