JP4178178B1 - Operation method of water purification membrane filtration equipment - Google Patents

Abstract

【Task】
An object of the present invention is to provide an operation method of a water purification membrane filtration facility that can optimize the operation conditions of the membrane filtration facility according to the raw water and the operation state of the facility and can easily grasp the operation state of the membrane filtration facility.
[Solution]
The membrane filtration control means 8 preliminarily calculates the raw water turbidity measured by the raw water quality meter 5 and the measured values of the membrane differential pressure measured by the primary pressure measuring means 6 and the secondary pressure measuring means 7. The filtration time is set based on the relationship between the membrane pressure difference and the filtration time for each raw water turbidity, the relationship between the membrane pressure difference and the filtration time for each raw water turbidity is displayed on the display means 9, and the filtration time Plot current and past values.
[Selection] Figure 1

Description

  The present invention relates to a method for operating a water purification membrane filtration facility for producing purified water including a membrane filtration treatment device installed for separating and removing turbidity and pathogenic protozoa contained in raw water.

  Since turbidity and pathogenic protozoa can be removed and maintenance is easy, the introduction of membrane filtration devices to water purification facilities is increasing. A clogging substance adheres to the primary side of the membrane module along with filtration, resulting in resistance to filtration. Therefore, in order to maintain a predetermined amount of filtered water, the membrane filtration control means increases the filtration pressure.

  Therefore, the membrane filtration control means removes clogging substances by a backwash process in which filtered water is periodically pumped from the secondary side to the primary side. In a membrane filtration apparatus that uses river water as raw water, the quality of the raw water changes due to rainfall and the like, and the amount of clogging of the membrane module changes. In the backwashing process under certain conditions, the washing cannot catch up with the accumulation of the clogging amount at the time of filtration, and the filtration pressure, that is, the membrane differential pressure may increase rapidly.

  For this reason, as described in [Patent Document 1] and [Patent Document 2], there is a method of changing the backwash interval, that is, the filtration time, according to the raw water quality and the membrane differential pressure.

JP 11-319516 A JP 2006-326472 A

  In the methods described in [Patent Document 1] and [Patent Document 2], the filtration time is automatically changed, but the function of displaying the history of operation condition change is not provided. For this reason, it is not a mechanism that allows the operator to easily grasp the driving situation, and there is a possibility that it takes time for the confirmation work.

  Further, in a membrane filtration facility equipped with a plurality of membrane modules, in order to reduce the construction cost, an operation method is adopted in which the membrane modules are backwashed one by one in sequence and one backwashing means is installed. . In this case, the lower limit of the filtration time is the product of the number of membrane modules to be backwashed, that is, the number of backwashing steps, and the backwash time. When a part of the membrane module is operated or stopped, the number of membrane modules to be backwashed changes, and the lower limit value of the filtration time changes.

  In the methods described in [Patent Document 1] and [Patent Document 2], the setting of the lower limit value of the filtration time and the number of operating membrane modules are not taken into account, and there is a possibility that the filtration time cannot be optimized.

  An object of the present invention is to provide an operation method of a water purification membrane filtration facility capable of optimizing the operation conditions of the membrane filtration facility according to raw water and the operation state of the facility.

  Another object of the present invention is to provide a method for operating a water purification membrane filtration facility that can easily grasp the operation status of the membrane filtration facility.

  In order to achieve the above object, the present invention provides a membrane filtration means including a membrane module for filtering raw water, a membrane differential pressure measuring means for measuring a membrane differential pressure of the membrane module, and a raw water quality measurement for measuring the quality of raw water. At least one of the means, and membrane filtration control means for controlling the filtration time, filtration flow rate, backwash time, and backwash flow rate of the membrane module, and at least one of the membrane differential pressure measurement means and the raw water quality measurement means It is an operation method of a water purification membrane filtration facility that changes the filtration time using a measurement value as an index, and obtains the filtration time from a diagram showing a relationship between a preset measurement value and the filtration time, and the current state on the diagram A value and a past value are displayed, and a plot color, a plot shape, and guidance are displayed according to the amount of change from the past value to the current value.

  In addition, pretreatment means for injecting a drug is provided upstream of the membrane filtration means, and the membrane filtration control means changes operating conditions of the pretreatment means according to the amount of change. Is.

  Membrane filtration means including a membrane module for filtering raw water, membrane differential pressure measuring means for measuring the membrane differential pressure of the membrane module, raw water quality measuring means for measuring the quality of raw water, filtration time of the membrane module, filtration A membrane filtration control means for controlling the flow rate, the backwash time, and the backwash flow rate, and the operation of the water purification membrane filtration equipment for changing the filtration time using the measured values of the membrane differential pressure measuring means and the raw water quality measuring means as indicators. In this method, the filtration time is obtained from a diagram showing the relationship between the measured value and the filtration time using the raw water quality as a parameter, and the current value and the past value are displayed on the diagram. Further, at least one of the plot color, the plot shape, and the guidance is changed and displayed according to the change amount and the change direction from the past value to the current value.

  In addition, pretreatment means for injecting a drug is provided upstream of the membrane filtration means, and the membrane filtration control means changes operating conditions of the pretreatment means in accordance with the amount of change and the change direction.

  A membrane filtration means including a plurality of membrane modules for filtering the raw water; and a membrane filtration control means for controlling the filtration time, filtration flow rate, backwash time, and backwash flow rate of the membrane module, and sequentially reverse the membrane modules. It is an operation method of the water purification membrane filtration equipment to be washed, and displays the lower limit value of the filtration time as a product of the number of the membrane modules in operation and the backwash time.

  ADVANTAGE OF THE INVENTION According to this invention, the driving | running condition of a membrane filtration equipment can be optimized according to the quality of raw | natural water, a membrane differential pressure | voltage, and the number of operation | movement of a membrane module. Moreover, since the operation history is displayed, it is possible to provide an operation method of the water purification facility that can easily grasp the operation state of the membrane filtration facility.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of a membrane filtration apparatus that is Embodiment 1 of the present invention. The membrane filtration device of this embodiment is installed in a purification facility that purifies raw water represented by surface water such as rivers.

  The membrane module 1 incorporates a hollow fiber MF membrane (microfiltration membrane) and a UF membrane (ultrafiltration membrane) to remove turbidity and fine particles in raw water.

  A filtration pump 2 is installed on the upstream side of the membrane module 1, and the filtration pump 2 can change the amount of filtered water in the membrane module 1. Filtrated water is stored in a filtrate water tank 3 installed on the downstream side of the membrane module 1, and from the secondary side of the membrane module 1 by a backwash pump 4 installed between the membrane module 1 and the filtrate water tank 3. Backwash water is supplied to remove turbidity accumulated on the membrane surface. The separated suspension containing turbidity is drained out of the system as backwash drainage from the pipe 12 with the valve 13.

  Switching between filtration and backwashing switches the operation of the filtration pump 2 and backwashing pump 4 and switches the valve 13 provided in the pipe 12 from closed to open. A raw water quality meter 5 for measuring the quality of raw water is installed upstream of the filtration pump 2. The raw water quality meter 5 measures one or more of turbidity, organic substance concentration, water temperature, pH, manganese concentration, suspended solid concentration, and the like. A primary pressure measuring means 6 is installed between the filtration pump 2 and the membrane module 1, and a secondary pressure measuring means 7 is installed between the membrane module 1 and the filtrate water tank 3. The raw water meter 5, the primary side pressure measuring means 6, and the measurement signal from the secondary side pressure measuring means 7 are input to the membrane filtration control means 8, and the membrane filtration control means 8 performs primary as necessary. The membrane differential pressure of the membrane module 1 is calculated from the difference between the pressure measuring means 6 on the side and the pressure measuring means 7 on the secondary side. Here, the raw water quality meter 5, the primary pressure measuring means 6, and the secondary pressure measuring means 7 are referred to as membrane differential pressure measuring means.

  The membrane filtration control means 8 outputs a signal for controlling the operation of the filtration pump 2 and the backwash pump 4, and changes the filtered water amount, the backwash water amount, the filtration time, and the backwash time. The input signal and output signal of the membrane filtration control means 8 are input to the display means 9, and the filtration time, membrane differential pressure, raw water quality and the like are displayed.

  Next, the operation method of the water membrane filtration equipment of the present embodiment will be described. The relationship between the filtration time and the membrane differential pressure or the raw water quality is input to the membrane filtration control means 8 in advance and displayed on the display means 9. As an example, the relationship between filtration time and membrane differential pressure is shown in FIG. Although FIG. 2 shows the relationship between the filtration time and the membrane differential pressure, the relationship between the filtration time and the raw water quality may be used. Further, the horizontal axis and the vertical axis may be interchanged.

  In the example shown in FIG. 2, the filtration time is a maximum of 100 minutes when the membrane differential pressure is 30 kPa or less. When the membrane differential pressure increases from 30 kPa to 100 kPa, the filtration time is shortened and the membrane differential pressure is reduced. Above 100 kPa, the minimum filtration time is set to 20 minutes. When the membrane differential pressure is used as an index, the membrane differential pressure changes even if the filtration flux is changed. Therefore, the relationship between the filtration time and the membrane differential pressure may be changed according to the filtration flux. The relationship between the filtration time and the membrane differential pressure may be linear approximation or curve approximation.

  The membrane filtration control means 8 sets the filtration time corresponding to the membrane differential pressure from the information on the membrane differential pressure. The white circles plotted on the diagram of FIG. 2 indicate the relationship between the current membrane differential pressure and the filtration time. The membrane filtration control unit 8 updates the membrane differential pressure information, for example, for a set time, when the membrane differential pressure at the time of resuming filtration after backwashing is stable, and immediately before backwashing.

  When the information on the membrane differential pressure is updated, the membrane filtration control means 8 shortens the filtration time according to the relationship shown in FIG. When the filtration time is shortened, the frequency of backwashing increases, so that an increase in membrane differential pressure can be suppressed. Moreover, when the membrane differential pressure decreases and becomes plot B, the membrane filtration control means 8 extends the filtration time according to the relationship shown in FIG. Since the frequency of backwashing is reduced, the amount of filtered water can be increased.

  Here, the white circle plot shown in FIG. 2 is defined as the past value, and the black circle plot is defined as the current value. If the amount of change from the past value to the current value is large, the amount of fluctuation in the membrane differential pressure will be large, and it is assumed that the quality of the raw water has changed greatly. Therefore, the membrane filtration control means 8 changes the plot color, plot shape, and guidance displayed on the display means 9 in accordance with the magnitude of the change amount. Guidance includes "Membrane differential pressure increase large", "Membrane differential pressure increase small", "Membrane differential pressure increase small", "Membrane differential pressure decrease small", "Membrane differential pressure decrease small", etc. Thus, since the history of operation conditions, the membrane differential pressure or raw water quality, and the relationship between the filtration times are displayed together, the operator can easily grasp the state of the equipment.

  The backwash time may be constant or may be changed according to the raw water quality and the membrane differential pressure. When changing, the backwash time should be increased by increasing the membrane differential pressure. Shortening the filtration time and increasing the backwash time decrease the recovery rate and the amount of fresh water. Therefore, the recovery rate and the amount of fresh water can be recovered by providing a second filtration device using backwash wastewater as treated water.

  According to the present embodiment, the filtration time of the membrane filtration equipment can be optimized according to the quality of raw water and the membrane differential pressure, and the operation status of the membrane filtration equipment can be easily grasped because the operation history is displayed.

  A second embodiment of the present invention is shown in FIG. Example 2 is configured in the same manner as Example 1, but in this example, as shown in FIG. 3, a pretreatment tank 11 is installed between the raw water quality meter 5 and the filtration pump 2. The processing means 10 is connected to the pretreatment tank 11.

  A flocculant or the like is injected into the pretreatment tank 11 by the pretreatment means 10, and the raw water and the flocculant are mixed in the pretreatment tank 11. The amount of the flocculant injected by the pretreatment means 10 is controlled by the membrane filtration control means 8. In many cases, the flocculant is injected to increase the particle size of the turbid material, and to take in organic matter into the agglomerated turbid material, thereby suppressing the membrane differential pressure. On the other hand, the injection of the flocculant increases the suspended solids and increases the burden on the wastewater treatment, so that optimization is desired.

  The operation method of the water membrane filtration equipment of the present embodiment will be described. The membrane filtration control means 8 calculates the membrane differential pressure from the information of the primary side pressure measurement means 6 and the secondary side pressure measurement means 7, and plots the past value and the current value on the diagram shown in FIG. Display on the display means 9.

  The increase / decrease amount of the flocculant injection rate is controlled by the amount of change from the past value to the current value. For example, the amount of change is classified into six stages of “large increase”, “increase”, “small increase”, “small decrease”, “decreasing”, “large decrease”, and “large increase” has a coagulant injection rate of 10 mg / L, “ “Increase” increases by 5 mg / L, and “Increase” increases by 2 mg / L. For example, the coagulant injection rate is reduced by 10 mg / L for “large reduction”, 5 mg / L for “decreasing”, and 2 mg / L for “small reduction”. Thus, the flocculant injection rate can be changed in accordance with the amount of change from the past value to the current value, that is, the fluctuation of the membrane differential pressure, and the status can be grasped by the display means 9.

  According to the present embodiment, the chemical injection amount of the pretreatment means 10 can be optimized according to the quality of raw water and the membrane differential pressure, and the change history of the filtration time of the membrane filtration equipment is displayed. Can be easily grasped.

  FIG. 4 shows a diagram for carrying out an operation method that is Embodiment 4 of the present invention. The difference between the diagram shown in FIG. 4 which is the present example and the diagram of FIG. 2 is that in this example, the relationship between the membrane differential pressure and the filtration time is classified according to the raw water quality. In the diagram shown in FIG. 4, turbidity is used as the quality of raw water, but suspended solid concentration, organic matter concentration, manganese concentration, etc. may be used. Similar to the first embodiment, the diagram shown in FIG. 4 is displayed on the display means 9.

  Next, the operation method of the membrane filtration control means 8 will be described. The membrane filtration control means 8 obtains the measured value of the raw water turbidity from the raw water quality meter 5 and the measured value of the membrane differential pressure from the primary side pressure measurement means 6 and the secondary side pressure measurement means 7. The turbidity and membrane pressure difference of the raw water obtained are plotted on the diagram shown in FIG. 4 to determine the filtration time.

  The membrane filtration control means 8 obtains the measured values of the raw water turbidity from the raw water quality meter 5 and the measured value of the membrane differential pressure from the primary pressure measuring means 6 and the secondary pressure measuring means 7 after the set time. . Use the updated plot as the current value, and update the filtration time from the turbidity and membrane pressure difference of the raw water obtained. In FIG. 4, the current value is indicated by a black circle and the past value is indicated by a white circle. With these plots, it is possible to show the history that the raw water turbidity and the membrane differential pressure are changed from white circles to black circles, and the operating conditions are changed.

  When the raw water turbidity is the same and the membrane differential pressure increases, it becomes plot A, and the filtration time is shortened and backwashing can be increased. Moreover, when the raw water turbidity is the same and the membrane differential pressure is reduced, the plot E is obtained and the filtration time is extended. The decrease in the membrane pressure difference is presumed that backwashing was sufficiently effective, so the filtration time can be extended.

  When the membrane differential pressure is the same and the raw water turbidity increases, plot B is obtained, and the filtration time is shortened. It is expected that clogging will progress due to an increase in raw water turbidity. By shortening the filtration time, an increase in the membrane pressure difference can be prevented. When the membrane differential pressure is the same and the raw water turbidity decreases, the plot F is obtained, and the filtration time is extended. Since clogging substances are reduced due to a decrease in raw water turbidity, it can be determined that the filtration time can be extended.

  When both the membrane differential pressure and the raw water turbidity increase, plot C is obtained, and the filtration time can be shortened compared to plot A and plot B, and the washing by backwashing can be enhanced. When both the membrane differential pressure and the raw water turbidity decrease, the plot G is obtained, and the filtration time can be extended as compared with the plot E and the plot F, and the amount of filtered water can be increased.

  When the raw water turbidity increases but the membrane differential pressure decreases, it becomes a plot H, and the membrane filtration control means 8 does not change the filtration time. Since the membrane pressure difference is decreasing, the current filtration time is maintained. Further, when the membrane differential pressure increases but the raw water turbidity decreases, the plot D is obtained, and the membrane filtration control means 8 does not change the filtration time. The current filtration time is maintained because the raw water turbidity is decreasing.

  In FIG. 4, the increase / decrease in membrane differential pressure and raw water turbidity can be classified according to the direction from the past value to the current value, that is, the change direction. The classification results are shown in FIG. 5. In “Region A”, both the membrane differential pressure and the raw water turbidity increase, in “Region A” the membrane differential pressure increases and the raw water turbidity decreases, and in “Region C”, the membrane difference Both the pressure and raw water turbidity decreased, and in "Region D", the membrane differential pressure decreased and the raw water turbidity increased. The order of the load on the membrane filtration apparatus and the degree of danger is “region a”> “region a”> “region d”> “region c”.

  The membrane filtration control means 8 changes and displays the plot color, shape and guidance on the display means 9 corresponding to the change amount and change direction. A large change amount indicates that the raw water quality and the membrane differential pressure are changing rapidly, and the driving risk can be determined by the change direction. The membrane filtration control means 8 classifies the amount of change into three, and weights each change direction, that is, for each region, so that the filtration time can be optimized. By determining the color and shape of the plot in order of the degree of risk, the operator can easily grasp the state of the equipment. Moreover, you may show a risk degree result as guidance. Since the history of operating conditions and the relationship between membrane differential pressure or raw water quality can be displayed together, the operator can easily understand the state of the equipment.

  According to this embodiment, the filtration time of the membrane filtration equipment can be optimized according to the quality of raw water and the membrane differential pressure. Moreover, since the operation history is displayed, the operation status of the membrane filtration equipment can be easily grasped.

  Embodiment 4 of the present invention will be described. As in FIG. 3, pretreatment means 12 for performing pretreatment such as drug injection is installed in the water purification membrane filtration equipment, and the diagram shown in FIG. 4 is displayed on the display means 9.

  The membrane filtration control means 8 uses FIG. 4 and FIG. 5 to control the drug injection amount of the pretreatment means 12 in accordance with the change amount and change direction from the past value to the current value, that is, the region. As an example, a case will be described in which the amount of change is classified into six stages of “large”, “medium”, and “small” by increasing and decreasing the membrane differential pressure, and classified into four regions as shown in FIG.

  The drug injection rate is set to ± 10 mg / L for “large”, ± 5 mg / L for “medium”, and ± 2 mg / L for “small”, and weighted for each region. “Region A” and “Region C” are 1.5 times, and “Region A” and “Region D” are 1.0 times. These results are shown in Table 1.

  All or part of the contents of Table 1 are displayed on the display means 9. As a result, the membrane filtration control means 8 can optimize the increase and decrease of the drug injection rate according to the change amount and the change direction, and can display the control amount.

  According to this example, the pretreatment chemical injection amount can be optimized according to the raw water quality and the membrane differential pressure, and the filtration time history of the membrane filtration facility and the flocculant injection amount can be displayed. The driving situation can be easily grasped.

  A fifth embodiment of the present invention will be described with reference to FIG. The present embodiment is configured in the same manner as in the first embodiment, but in the first embodiment, it is a membrane module, but in this embodiment, the membrane module unit is composed of a plurality of membrane modules. Corresponding to the plurality of membrane modules 1-1 to 1-4, filtration pumps 2-1 to 2-4, primary-side pressure measuring means 6-1 to 6-4, and secondary-side pressure measuring means 7- 1-7-4 are added. One backwash pump 4 is installed because it is controlled so as to sequentially backwash each membrane module.

  In this case, the lower limit of the filtration time is the product of the backwash time and the number of membrane modules to be backwashed. In some cases, a part of the membrane module is stopped, and it is necessary to change the lower limit of the filtration time depending on the number of membrane modules in operation.

  The operation method of the membrane filtration control means 8 will be described. The membrane filtration control means 8 obtains information on the number of membrane modules in operation and preset backwash time from the operation state of the filtration pumps 2-1 to 2-4. Next, the product of the number of membrane modules in operation and the backwash time is obtained and displayed in the diagram shown in FIG. 2 or FIG.

  When four membrane modules 1-1 to 1-4 are operating, and the backwash time is 6 minutes, the lower limit of the filtration time is 24 minutes. The backwash time is a time including the start time of the backwash pump and the opening / closing time of the valve of the pipe. The result of adding the lower limit of the filtration time is shown in FIG. The membrane filtration control means 8 sets the filtration time according to FIG. 7 in which the lower limit value of the filtration time is updated.

  According to the present embodiment, the operating conditions of the membrane filtration equipment can be automatically changed according to the quality of raw water, the membrane differential pressure, and the number of operating membrane modules. Moreover, since the operation history is displayed, it is possible to provide an operation method of the water purification facility that can easily grasp the operation status of the membrane filtration facility.

The block diagram of the water purification membrane filtration equipment which is Example 1 of this invention. The diagram which shows an example of the driving | running method of a present Example. The block diagram of the water purification membrane filtration equipment which is Example 2 of this invention. The diagram which shows an example of the driving | running method. The diagram which shows an example of the driving | running method. The block diagram of the water purification membrane filtration equipment which is Example 5 of this invention. The diagram which shows an example of the driving | running method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Membrane module 2 Filtration pump 3 Filtration water tank 4 Backwash pump 5 Raw water quality meter 6 Primary side pressure measurement means 7 Secondary side pressure measurement means 8 Membrane filtration control means 9 Display means 10 Pretreatment means 11 Pretreatment tank

Claims (6)

Membrane filtration means including a membrane module for filtering raw water, at least one of membrane differential pressure measurement means for measuring the membrane differential pressure of the membrane module and raw water quality measurement means for measuring the quality of raw water, and filtration time of the membrane module , Filtration flow rate, backwash time, membrane filtration control means for controlling the backwash flow rate, and using the measured value of at least one of the membrane differential pressure measurement means and the raw water quality measurement means as an index, the filtration time of the membrane module a method of operating a water purification membrane filtration equipment to be changed, the filtration time relationship with a preset the transmembrane pressure difference measured value, or a diagram showing the raw water quality measurements and said filtered time relationship, said membrane seeking filtration time corresponding to a differential pressure measurement or raw water quality measurements to set the filtration time of the membrane module, the membrane by the membrane filtration control means such that the filtering time of the set membrane module Controls filtration time of the Joule, the membrane module operating method of water purification membrane filtration equipment to be displayed by plotting the position of the previous value before the change and the current value after the change of the filtration time of the line drawing on the display means.   The operation method of the water purification membrane filtration equipment according to claim 1, wherein at least one of plot color, plot shape, and guidance is displayed in accordance with an amount of change from the past value to the current value.   The pretreatment means which inject | pours a chemical | medical agent in the upstream of the said membrane filtration means is provided, The said membrane filtration control means changes the driving | running condition of this pretreatment means according to the said variation | change_quantity. how to drive. Membrane filtration means including a membrane module for filtering raw water, membrane differential pressure measuring means for measuring the membrane differential pressure of the membrane module, raw water quality measuring means for measuring the quality of raw water, filtration time of the membrane module, filtration Membrane filtration control means for controlling the flow rate, backwash time, backwash flow rate, and water filtration membrane filtration for changing the filtration time of the membrane module using the measured values of the membrane differential pressure measuring means and the raw water quality measuring means as an index The operation method of the equipment, wherein the membrane differential pressure measurement value of the membrane differential pressure measuring means and the relationship between the filtration time are set in advance at different slopes depending on the raw water quality measurement value of the raw water quality measurement means , and the membrane seeking filtration time corresponding to the differential pressure measurement value and the raw water quality measurements to set the filtration time of the membrane module, the membrane module by the membrane filtration control means such that the filtering time of the set membrane module Controls filtration time, the membrane module operating method of water purification membrane filtration equipment to be displayed by plotting the position of the previous value before the change and the current value after the change of the filtration time of the line drawing on the display means.   The operation of the water purification membrane filtration equipment according to claim 4, wherein at least one or more of the plot color, the plot shape, and the guidance is changed and displayed according to a change amount and a change direction from the past value to the current value. Method.   The pretreatment means which inject | pours a chemical | medical agent upstream of the said membrane filtration means is provided, The said membrane filtration control means changes the operating condition of this pretreatment means according to the said variation | change_quantity and the said change direction. Operation method of water purification membrane filtration equipment.

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