WO2022234751A1

WO2022234751A1 - Analysis method and analysis device for membrane-occluding substance, and chemical-solution injection control method and chemical-solution injection control device for separation membrane

Info

Publication number: WO2022234751A1
Application number: PCT/JP2022/016068
Authority: WO
Inventors: 卓木田; 勇規中村
Original assignee: オルガノ株式会社
Priority date: 2021-05-06
Filing date: 2022-03-30
Publication date: 2022-11-10
Also published as: TW202308751A; JPWO2022234751A1

Abstract

This analysis method for a membrane-occluding substance includes: projecting visible light onto a monitoring-use separation membrane through which test water has been passed; measuring, using a visible light spectrophotometer, the reflection intensity of the visible light reflected by the monitoring-use separation membrane; and identifying the occluding substance in the membrane on the basis of the reflection intensity of the visible light which was measured.

Description

Membrane clogging substance analysis method and analysis device, separation membrane chemical injection control method and chemical injection control device

The present invention relates to a method and apparatus for analyzing a membrane clogging substance that clogs a separation membrane, and a method and apparatus for controlling chemical injection of the separation membrane.

In a water treatment system that uses a separation membrane to treat water to be treated, it is known that the membrane is gradually clogged by membrane clogging substances contained in the water to be treated. As the clogging of the separation membrane progresses, the efficiency of water treatment decreases. Therefore, generally, a washing chemical such as an acid or an alkali is used to dissolve and remove the membrane clogging substances, thereby restoring the separation membrane to its initial state. The conditions for washing the separation membrane using the washing chemical (type, concentration, washing flow rate, water temperature, etc.) of the washing chemical are determined according to the progress of membrane clogging, the type of membrane clogging substance, and the like.

The degree of membrane clogging and the type of membrane clogging material can be determined, for example, by stopping the operation of the water treatment system and removing the clogged separation membrane, or by replacing it with an unused separation membrane and analyzing the clogged separation membrane. can be considered. However, such a method has the problem that it takes time and effort to remove the separation membrane, reinstall it after cleaning, or replace the separation membrane, and it takes time to obtain analysis results. Therefore, techniques for estimating the degree of progress of membrane occlusion and techniques for identifying the type of membrane occlusion substance are being studied.

For example, in Patent Document 1, part of the concentrated water separated by the separation membrane is sent to the monitoring separation membrane, and the absolute value of the permeation amount of the concentrated water in the monitoring separation membrane or its change rate, the monitoring separation membrane describes a technique for estimating the degree of clogging of a separation membrane based on the absolute value of the differential pressure of the concentrated water before and after permeation or the rate of change thereof.

Further, in Patent Document 2, a membrane separation device equipped with a separation membrane is configured with a transparent resin or the like, and the membrane surface of the separation membrane is observed over time with a color sensor to detect membrane clogging that adheres to the membrane surface. Specifying the type of substance is described.

The above-mentioned Patent Document 1 proposes a technique for estimating the progress of membrane clogging, and does not specify the type of membrane clogging substance adhering to the membrane surface of the separation membrane. Therefore, the technique described in Patent Document 1 has a problem that an appropriate chemical solution cannot be selected according to the type of membrane blocking substance.

On the other hand, in the water treatment system described in Patent Document 2, since the membrane clogging substance is identified from the color of the membrane surface observed by the color sensor, there is a problem that the types of discriminable membrane clogging substances are limited. .

JP 2012-130823 A JP 2019-166463 A

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the background art as described above, and is a method and apparatus for analyzing a membrane-blocking substance that can identify more types of membrane-blocking substances, and the analysis method. It is an object of the present invention to provide a separation membrane chemical injection control method and a chemical injection control device using an analyzer.

In order to achieve the above object, the method for analyzing a membrane clogging substance of the present invention comprises irradiating a monitoring separation membrane through which test water is passed with visible light,
measuring the reflection intensity of the visible light reflected by the monitoring separation film with a visible light spectrophotometer;
A method for identifying a membrane blocking substance based on the measured reflection intensity of the visible light.

The apparatus for analyzing a membrane clogging substance of the present invention comprises a monitoring separation membrane through which test water is passed;
a visible light spectrophotometer for irradiating the monitoring separation film with visible light and measuring the reflection intensity of the visible light reflected by the monitoring separation film;
a computing device that identifies a film blocking substance based on the measured reflection intensity of the visible light;
have

In the separation membrane chemical injection control method of the present invention, the water to be treated is separated into permeated water and concentrated water by the separation membrane,
Part of the concentrated water is passed through a monitoring separation membrane as test water,
irradiating the monitoring separation membrane through which the test water is passed with visible light;
measuring the reflection intensity of the visible light reflected by the monitoring separation film with a visible light spectrophotometer;
identifying a film blocking substance that blocks the separation film based on the measured reflection intensity of the visible light;
This is a method of injecting a chemical solution for dissolving and removing the specified membrane clogging substance or a chemical solution for suppressing membrane clogging by the specified membrane clogging substance into the water flow line of the separation membrane.

The chemical dosing control device for a separation membrane of the present invention includes a membrane separation device equipped with a separation membrane that separates water to be treated into permeated water and concentrated water,
a monitoring separation membrane through which part of the concentrated water is passed as test water;
a visible light spectrophotometer for irradiating the monitoring separation membrane through which the test water is passed with visible light and measuring the reflection intensity of the visible light reflected by the monitoring separation membrane;
an arithmetic device for identifying a film blocking substance that blocks the separation film based on the measured reflection intensity of the visible light;
a control device for injecting a chemical solution for dissolving and removing the specified membrane clogging substance or a chemical solution for suppressing membrane clogging by the specified membrane clogging substance into the water flow line of the separation membrane;
have

1 is a block diagram showing one configuration example of a chemical feeding control device for a separation membrane according to the present invention; FIG. FIG. 2 is a side sectional view showing one configuration example of the analysis device shown in FIG. 1; FIG. 3 is a block diagram showing a modification of the chemical feeding control device for the separation membrane of the present invention; 4 is a graph showing an example of changes in the spectrum of a membrane blocking substance; 4 is a graph showing an example of changes in the spectrum of a membrane blocking substance; FIG. 6 is a table showing an example of spectral data of assumed substances shown in FIGS. 4 and 5; FIG. FIG. 6 is a table showing parameters used in the method for analyzing a membrane blocking substance of an example obtained from the spectral data shown in FIGS. 4 and 5; FIG. 4 is a flow chart showing an example of a processing procedure according to an embodiment; FIG. 6 is a table showing parameters used in a comparative method for analyzing a membrane blocking substance obtained from the spectral data shown in FIGS. 4 and 5. FIG.

Next, the present invention will be explained using the drawings.

In the present invention, "membrane blockage" means a state in which a membrane blockage substance adheres to at least a part of the membrane surface, and does not limit the progress of membrane blockage. The extent to which membrane clogging progresses before starting cleaning of the separation membrane may be set according to the purpose of water treatment, the type of water to be treated, the components contained in the water to be treated, the purity of the permeated water, and the like. Separation membranes to which the present invention can be applied include, for example, reverse osmosis membranes, microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, forward osmosis membranes, deaeration membranes, and decarbonation membranes.

FIG. 1 is a block diagram showing one configuration example of the separation membrane chemical feeding control device of the present invention, and FIG. 2 is a side sectional view showing one configuration example of the analyzer shown in FIG. FIG. 3 is a block diagram showing a modification of the chemical feeding control device for the separation membrane of the present invention. The separation membrane chemical dosing control device of the present invention shown in FIGS. 1 to 3 constitutes a part of a water treatment system for treating water to be treated using a separation membrane.

As shown in FIG. 1, the separation membrane chemical dosing control device of the present invention includes a raw water tank 1 that stores water to be treated, and separates the water to be treated supplied from the raw water tank 1 into concentrated water and permeated water. A membrane separation device 2 equipped with a separation membrane, and an analysis device 3 for identifying the type of membrane clogging substance adhering to the separation membrane, to which part of the concentrated water separated by the membrane separation device 2 is supplied as test water. , a chemical liquid tank 4 for storing a cleaning chemical liquid for cleaning the separation membrane, and a control device 5 for controlling the operation of the entire chemical injection control device for the separation membrane. Although FIG. 1 shows a configuration example in which the separation-membrane chemical-feeding control device includes one chemical tank 4 , the separation-membrane chemical-feeding control device may be configured to have a plurality of chemical tanks 4 . In that case, different types of chemical liquids may be stored in the plurality of chemical liquid tanks 4 .

In addition to the above configuration, the separation membrane chemical feeding control device shown in FIG. It is equipped with a chemical injection pump 12 for injecting a chemical solution and a plurality of valves 13 arranged in a water flow line for discharging the concentrated water separated by the membrane separation device 2 to the outside. When the separation membrane chemical feeding control device has a plurality of chemical liquid tanks 4 , the separation membrane chemical feeding control device may include a plurality of chemical feeding pumps 12 according to the number of chemical liquid tanks 4 . In FIG. 1, as the plurality of valves 13, a first valve 13A arranged in the water flow line between the membrane separation device 2 and the analysis device 3, and a water flow line between the analysis device 3 and the raw water tank 1 and a third valve 13C for discharging the concentrated water separated by the membrane separation device 2 that is not sent to the analysis device 3 to the outside. The second valve 13B is provided to return the chemical solution to the raw water tank 1 through the water line for the concentrated water separated by the membrane separator 2 when the chemical solution is injected (chemical injection). A second valve 13B may also be used to return concentrated water to the raw water tank 1 during normal operation. The separation membrane chemical feeding control device of the present invention does not need to be configured to return the concentrated water or the chemical solution to the raw water tank 1 . The plurality of valves 13 may be appropriately provided according to the configuration and operation of the chemical injection control device for the separation membrane. Similarly, the plurality of pumps are not limited to the raw water pump 11 and the chemical injection pump 12, and may be appropriately provided according to the configuration and operation of the chemical injection control device for the separation membrane.

The water to be treated stored in the raw water tank 1 is supplied to the membrane separation device 2 by the raw water pump 11 . The membrane separation device 2 separates the water to be treated into permeated water containing substances that permeate the separation membrane and concentrated water containing substances that do not permeate the separation membrane. The permeated water is discharged as treated water. Alternatively, the permeated water is treated by another membrane separation device, ion exchange device, or the like, and discharged as treated water. The concentrated water is discharged as waste water. Alternatively, the concentrated water is treated with another membrane separation device, a biological treatment device, a solid-liquid separation device, or the like, and discharged.

As shown in FIG. 1, the chemical liquid stored in the chemical liquid tank 4 is injected into the water passage line of the separation membrane provided in the membrane separation device 2 . For example, the chemical solution may be injected into the raw water tank 1, or may be injected into the water flow line between the raw water pump 11 and the membrane separator 2, and the membrane separator 2 and the analyzer 3 may be injected. may be injected into the flow line of the concentrate between The chemical liquid stored in the chemical liquid tank 4 is selected according to the type and properties of the membrane blocking substances expected to be generated based on the type of the water to be treated, the components contained in the water to be treated, and the like. Types of chemical solutions include acidic chemical solutions, alkaline chemical solutions, surfactants, and the like, which are used to dissolve and remove membrane clogging substances and wash separation membranes. As the chemical liquid, a slime control agent, a scale dispersant, or the like used for suppressing (delaying) membrane clogging caused by a membrane clogging substance may be used.

The control device 5 controls the operation of the entire separation membrane chemical injection control device of the present invention by controlling the raw water pump 11, the chemical injection pump 12, and the plurality of valves 13, respectively. In addition, based on the analysis result of the analyzer 3, the control device 5 injects the chemical liquid stored in the chemical liquid tank 4 into the water flow line of the separation membrane. When the separation membrane chemical dosing control device has a plurality of chemical liquid tanks 4, the control device 5 controls a plurality of types of chemical liquid stored in the plurality of chemical liquid tanks 4 according to the type of the membrane clogging substance identified by the analyzer 3. A chemical liquid selected from the chemical liquids may be injected into the water flow line of the separation membrane. At the time of chemical injection to the water passage line of the separation membrane, the control device 5 may open the first valve 13A and the second valve 13B and close the third valve 13C to circulate the chemical solution. The control device 5 can be realized by, for example, a well-known PLC (Programmable Logic Controller). The control device 5 may be realized by a known information processing device (computer) including a CPU (Central Processing Unit), a storage device, an I/O interface, a communication device, and the like.

As shown in FIGS. 1 and 2, the analyzer 3 includes a raw water chamber 31, a permeated water chamber 32, a monitoring separation membrane 33, a visible light spectrophotometer 34, and an arithmetic unit 35. The monitoring separation membrane 33 It is provided so as to separate the chamber 31 and the permeated water chamber 32 . The raw water chamber 31 , the permeated water chamber 32 and the monitoring separation membrane 33 constitute the monitoring cell 30 .

A part of the concentrated water separated by the membrane separation device 2 is supplied to the monitoring separation membrane 33 as test water, and the test water is further separated into concentrated water and permeated water. For the monitoring separation membrane 33, it is preferable to use the same kind of separation membrane as the separation membrane provided in the membrane separation device 2. FIG. Furthermore, it is more preferable to use a membrane manufactured by the same manufacturer as the separation membrane provided in the membrane separation device 2 for the monitoring separation membrane 33 .

The raw water chamber 31 is supplied with the test water and discharges concentrated water containing substances that do not permeate the monitoring separation membrane 33 . Permeated water containing substances that have permeated the monitoring separation membrane 33 is discharged from the permeated water chamber 32 . The raw water chamber 31 and the permeated water chamber 32 are each composed of a member that transmits visible light, and a visible light spectrophotometer 34 is arranged on the outer wall surface of the raw water chamber 31 facing the film surface of the separation membrane 33 for monitoring. The raw water chamber 31 and the permeated water chamber 32 may be composed of any member as long as it transmits visible light, and may be composed of, for example, an acrylic plate, a glass plate, quartz, plastic, or the like. . The raw water chamber 31 and the permeated water chamber 32 may be formed individually or integrally.

The visible light spectrophotometer 34 includes an illumination unit that irradiates visible light and a measurement unit that measures the reflection intensity of each wavelength of visible light. , the reflection intensity for each wavelength of the visible light reflected by the film surface is measured by the measurement unit. The measurement unit of the visible light spectrophotometer 34 should be able to measure the reflection intensity of light of at least four wavelengths in the visible light region of 400 to 800 nm. For example, the measurement unit may measure the reflection intensity of at least one or more wavelengths of light in the wavelength regions of 400 to 450 nm, 450 to 500 nm, 600 to 700 nm, and 700 to 800 nm. The illumination unit may have any known configuration as long as it can irradiate light with a wavelength in the visible light region. The visible light spectrophotometer 34 measures the reflection intensity of the visible light reflected by the film surface of the monitoring separation film 33 at predetermined intervals, and transmits the measured data to the arithmetic device 35 .

Upon receiving the measurement data of the reflection intensity from the visible light spectrophotometer 34, the arithmetic device 35 estimates the type of substance adhering to the film surface of the monitoring separation membrane 33 based on the measurement data, and separates the estimated substance. It is notified to the controller 5 as a membrane clogging substance. At this time, the computing device 35 may estimate the progress of membrane clogging of the monitoring separation membrane 33 and transmit the estimation result to the control device 5 together. The calculation device 35 or the control device 5 outputs the estimation result of the membrane clogging substance, the estimation result of the degree of membrane clogging, etc. to the water supply including the separation membrane chemical injection control device of the present invention using an output device such as a display device. The administrator of the processing system or the like may be notified.

The separation membrane chemical dosing control device shown in FIGS. 1 and 2 shows a configuration example in which part of the concentrated water separated by the membrane separation device 2 is supplied to the monitoring cell 30 as test water. As shown in FIG. 3, the separation membrane chemical feeding control device of the present invention may be configured to supply part of the water to be treated stored in the raw water tank 1 to the monitoring cell 30 as test water. In that case, the first valve 13A may be moved to, for example, the water flow line between the raw water pump 11 and the analyzer 3 as shown in FIG.

In the present invention, one or more membrane clogging substances (hereinafter referred to as , called hypothetical substances) are selected, and data (spectral data) of reflection intensity in visible light for each hypothetical substance is measured in advance. In addition, the data of the reflection intensity of the unused monitoring separation film (=separation film, hereinafter referred to as the unused film) in visible light is also measured in advance. Then, the slope (first slope), which is the difference in reflection intensity with respect to the difference in wavelength light for each of the unused film and assumed substance, and the value of the reflection intensity for light of a specific wavelength, calculated from the spectral data, are calculated by the computing device. 35 storage devices, respectively.

The computing device 35 collects previously measured reflection intensity data for each wavelength light of the unused membrane and assumed substance, and the monitoring separation membrane through which the test water is passed when the water treatment system is operated (hereinafter referred to as By comparing the reflection intensity data for each wavelength light of the monitored film), the film blocking substance is specified. More specifically, the computing device 35 measures reflection intensity data for each of four or more wavelengths of light in the visible light region for the unused film and assumed substance, and obtains the unused The reflection intensity and the slope are stored for each film and assumed substance. In addition, discrimination conditions for discriminating a film clogging substance, which are set based on the reflection intensity and inclination for each of the unused film and assumed substance, are stored. When the visible light spectrophotometer 34 measures the reflection intensity for each wavelength of the monitored film, the determination condition is used to specify the film blocking substance from the measured data of the monitored film.

When estimating the degree of progress of membrane clogging, the computing device 35, for example, the absolute value of the permeation amount of concentrated water in the monitoring separation membrane 33 or its change rate, the monitoring separation A method of estimating the degree of clogging of the separation membrane based on the absolute value of the differential pressure of the concentrated water before and after permeation through the membrane 33 or its rate of change may be used.

　It is desirable to always include light with a wavelength of 400 to 450 nm or 700 to 800 nm in the visible light region in the measurement of reflection intensity. The inventors conducted an experiment that when a membrane-occluding substance adheres to the membrane surface of the separation membrane (monitoring separation membrane 33), the reflection intensity in these wavelength light ranges is lower than that of an unused membrane. etc. is confirmed. Therefore, by including the wavelength light of 400 to 450 nm or 700 to 800 nm in the reflection intensity measurement, it is possible to determine whether or not the film to be monitored is clogged.

The computing device 35 may be realized by an information processing device (computer) including, for example, a CPU, a storage device, an I/O interface, a communication device, and the like. If the control device 5 is implemented by an information processing device (computer), the functions of the arithmetic device 35 may be implemented by the control device 5 . In that case, the visible light spectrophotometer 34 may transmit the measurement data of the reflection intensity for each wavelength light to the control device 5 . The communication means between the visible light spectrophotometer 34 and the arithmetic device 35 (or the control device 5) and the communication means between the arithmetic device 35 and the control device 5 may be known wired communication means or wireless communication means. Any well-known standard may be used as the communication standard.

As described above, the control device 5 injects the chemical liquid stored in the chemical liquid tank 4 into the water flow line of the separation membrane based on the membrane clogging substance identified by the analyzer 3 . For example, when the membrane blocking substance is identified as calcium scale, an acidic chemical solution is injected, and when the membrane blocking substance is identified as silica or biofouling, an alkaline chemical solution is injected. By washing the separation membrane using an appropriate washing chemical according to the type of membrane clogging substance, the function of the separation membrane can be recovered. The control device 5 may use pure water or the like to flush each water flow line provided in the chemical injection control device for the separation membrane of the present invention before injecting the chemical solution.

Further, the control device 5 may inject a chemical solution for the purpose of suppressing (delaying) the occurrence of clogging of the separation membrane into the water flow line of the separation membrane. For example, when the membrane clogging substance is identified as slime by biofouling, a slime control agent is injected, and when the membrane clogging substance is identified as an inorganic substance such as calcium fluoride (CaF ₂ ) or silica. can be injected with a scale dispersant. If the membrane clogging substance is a substance that can suppress the occurrence of membrane clogging by controlling the pH, such as calcium carbonate (CaCO ₃ ), the occurrence of membrane clogging can be suppressed by injecting an acidic or alkaline chemical. good.

In this way, by injecting an appropriate chemical solution during operation of the water treatment system to suppress clogging of the separation membrane, the water treatment system can be operated stably for a relatively long period of time. In addition, if it is confirmed that the generation of membrane clogging substances is suppressed, it is possible to reduce the running cost of the water treatment system by reducing the amount of slime control agent, scale dispersant, etc. injected. be.

According to the present invention, with respect to the unused film and the assumed substance, the reflection intensity data for each of four or more wavelengths in the visible light region are measured, and the unused film and the assumed substance obtained from the measurement data The reflection intensity and the slope are saved. Further, discrimination conditions for discriminating a membrane blocking substance, which are set in advance based on the reflection intensity and inclination of each unused film and assumed substance, are stored. When the visible light spectrophotometer 34 measures the reflection intensity data for each wavelength light of the monitored film, the determination condition is used to identify the film blocking substance from the measured data of the monitored film. Therefore, it becomes possible to identify more types of membrane-occlusive substances.

Next, an embodiment of the present invention will be described with reference to the drawings.

4 and 5 are graphs showing an example of changes in the spectrum of the assumed substance.

In this embodiment, a plurality of separation membranes (=monitoring separation membranes 33, hereinafter referred to as blocking membranes) to which the assumed substance is intentionally adhered and the unused membranes are prepared, and the visible light spectrophotometer 34 was used to measure the reflection intensity of the unused film and the blocking film for each wavelength of light. As the visible light spectrophotometer 34, a hyperspectral camera (Pika L manufactured by RESONON) with a measurement wavelength range of 400 to 1000 nm was used.

Separation membranes to which calcium carbonate (CaCO3), calcium fluoride (CaF ₂ ) and silica (SiO ₂ ) were adhered, and biofouled separation membranes were prepared as the blocking membranes. Then, an unused film and a plurality of blocking films are respectively arranged on the operating stage, visible light is irradiated to the unused film and the blocking film, and the reflection intensity of each wavelength light reflected by each film surface is measured by the hyperspectral camera. measured in

In addition, the reflection intensity was measured in the range of 450 to 600 nm wavelength light for the blocking film with calcium carbonate, calcium fluoride, and silica adhered together with the unused film. The graph of FIG. 4 shows the reflection intensity (spectrum) for each wavelength light of these separation films. In addition, the reflection intensity of the biofouled clogging membrane was measured together with the unused membrane in the wavelength range of 400 to 1000 nm. The graph of FIG. 5 shows the reflection intensity (spectrum) for each wavelength light of these separation films. Here, the measurement range of wavelength light is different between the blocking film to which calcium carbonate, calcium fluoride, and silica are attached and the blocking film to which biofouling is applied. It may be set so that the spectrum of each assumed substance can be identified, and may be appropriately set within the visible light region of 400 to 800 nm according to the properties of the unused film and the assumed substance.

Next, an analysis method for identifying the membrane blocking substance based on the measurement data (spectrum data) of the reflection intensity of the unused membrane and the blocking membrane will be described.

FIG. 6 is a table showing an example of spectral data of the hypothetical substance shown in FIGS. 4 and 5, and FIG. 7 is a method for analyzing a membrane blocking substance of the example obtained from the spectral data shown in FIGS. It is a table showing parameters used in.

FIG. 6 extracts the measurement data of light at five wavelengths of 400 nm, 450 nm, 600 nm, 700 nm, and 800 nm from the measurement data (spectrum data) of the reflection intensity of the unused film and the closed film shown in FIGS. is shown.

FIG. 7 shows the sum of the reflection intensities at wavelengths of 400 and 450 nm and the wavelength of 400 for the unused film and assumed material, calculated from the measurement data of the reflection intensity of the unused film and the blocking film shown in FIGS. and 450 nm, and the slopes at wavelengths of 600 and 800 nm, respectively.

As described above, whether or not the film to be monitored is clogged can be determined by comparing the reflection intensity of the unused film and the reflection intensity of the film to be monitored at wavelengths of light of 400 to 450 nm or 700 to 800 nm. However, there is a possibility that the difference is so small that it is difficult to distinguish between the reflection intensities of light of only one wavelength. Therefore, in this embodiment, the sum of the reflection intensities of the two wavelength lights of 400 nm and 450 nm shown in FIG. 7 is used to determine whether or not the film to be monitored is clogged.

The slope (first slope) in the unused film and assumed material is the difference in the reflection intensity of the wavelength light with respect to the wavelength light difference, that is, the difference in the reflection intensity of the two wavelength lights divided by the wavelength difference. You can find it with For example, the slope for light with wavelengths of 600 and 800 nm can be obtained by the following formula.

Tilt (600nm, 800nm)
= (reflection intensity 800 nm-reflection intensity 600 nm)/(800 nm-600 nm)
Next, a method for analyzing membrane blocking substances according to the present embodiment will be described with reference to a flow chart.

FIG. 8 is a flowchart showing an example of the processing procedure of the embodiment. It is assumed that the calculation device 35 stores the total reflection intensity value and the slope value calculated from the measurement data of the reflection intensity for each of the unused film and assumed material (see FIG. 7). Further, it is assumed that the computing device 35 stores respective determination conditions for specifying membrane blocking substances. As a determination condition, as will be described later, for example, the inclination of the monitored film at wavelengths of 600 and 800 nm is twice or more the inclination of the unused film, or the inclination of the monitored film at wavelengths of 400 and 450 nm is unused. For example, whether the tilt of the monitored film is 1.5 times or more the tilt of the film, or whether the tilt of the monitored film at wavelengths of 400 and 450 nm is 0.5 times or less than the tilt of the unused film. The determination conditions are not limited to these, and the slope (first slope) of light of each wavelength for each unused film and assumed substance is determined so that the substance adhering to the monitored film (membrane blocking substance) can be determined. can be set in advance based on

As shown in FIG. 8, when the calculation device 35 receives the measurement data of the reflection intensity of the monitored film from the visible light spectrophotometer 34, it calculates the total value of the reflection intensity of the monitored film at wavelengths of 400 and 450 nm. (Step S1), it is determined whether or not membrane occlusion has occurred in the membrane to be monitored (Step S2). As described above, the computing device 35 determines that film clogging occurs in the monitored film when the total value of the reflection intensities of the monitored film at wavelengths of 400 and 450 nm is smaller than the total value of the reflection intensities of the unused film. It should be determined that

When it is determined that the membrane to be monitored is not blocked, the arithmetic device 35 returns to step S1 and repeats the processing from step S1. On the other hand, when it is determined that the monitored film is blocked, the arithmetic device 35 shifts to the process of step S3 and calculates the tilt of the monitored film for the wavelength light of 600 and 800 nm.

Subsequently, the computing device 35 determines whether or not the tilt of the film to be monitored at wavelengths of 600 and 800 nm is greater than the tilt of the unused film (eg, twice or more) (step S4).

When the slope of the monitored membrane at wavelengths of 600 and 800 nm is more than twice the slope of the unused membrane, it is highly likely that the membrane clogging material is biofouling, as shown in FIG. In this case, the arithmetic device 35 transmits information for notifying the control device 5 that the membrane blocking substance is biofouling (step S5), returns to the processing of step S1, and repeats the processing from step S1. .

When the control device 5 is notified from the arithmetic device 35 that the membrane clogging substance is biofouling, in the case of cleaning the separation membrane, an alkaline chemical is injected to clean the separation membrane (monitoring separation membrane 33). do. Also, when suppressing the occurrence of membrane blockage, the dosage of the slime control agent is increased.

On the other hand, in step S4, if the tilt of the monitored film at wavelengths of 600 and 800 nm is less than twice the tilt of the unused film, the film blocking substance is calcium carbonate, silica, or calcium fluoride, as shown in FIG. Very likely. In this case, the arithmetic unit 35 shifts to the process of step S6 and calculates the tilt of the monitored film for the wavelength light of 400 and 450 nm.

Subsequently, the arithmetic device 35 determines whether or not the tilt of the film to be monitored at wavelengths 400 and 450 nm is greater than the tilt of the unused film (for example, 1.5 times or more) (step S7). .

If the slope of the monitored film at wavelengths of 400 and 450 nm is 1.5 times or more than the slope of the unused film, it is highly likely that the film blocking substance is calcium carbonate, as shown in FIG. In this case, the arithmetic device 35 transmits information for notifying the control device 5 that the membrane blocking substance is calcium carbonate (step S8), returns to the processing of step S1, and repeats the processing from step S1.

When the control device 5 is notified by the computing device 35 that the membrane clogging substance is calcium carbonate, when cleaning the separation membrane, it injects an acidic chemical solution to clean the separation membrane (monitoring separation membrane). In addition, when suppressing the occurrence of membrane clogging, the occurrence of membrane clogging is suppressed by injecting an acidic chemical solution or an alkaline chemical solution to control the pH.

In step S7, if the tilt of the monitored film at wavelengths of 400 and 450 nm is less than 1.5 times the tilt of the unused film, the film blocking substance may be silica or calcium fluoride, as shown in FIG. is high. In this case, the arithmetic unit 35 shifts to the process of step S9, and determines whether or not the tilt of the film to be monitored at wavelengths of 400 and 450 nm is smaller than the tilt of the unused film (for example, 0.5 times or less). judge.

If the slope of the monitored film at wavelengths of 400 and 450 nm is less than 0.5 times the slope of the unused film, it is highly possible that the film blocking substance is silica, as shown in FIG. In this case, the arithmetic device 35 transmits information for notifying the control device 5 that the membrane blocking substance is silica (step S10), returns to the processing of step S1, and repeats the processing from step S1.

When the control device 5 is notified by the computing device 35 that the membrane clogging substance is silica, when cleaning the separation membrane, it injects an alkaline chemical solution to clean the separation membrane (monitoring separation membrane 33). Also, in order to suppress the occurrence of membrane clogging, the dosage of the scale dispersant is increased. The control device 5 may control the pH by injecting an acidic chemical solution or an alkaline chemical solution to suppress the occurrence of membrane clogging.

On the other hand, if the slope of the monitored film at wavelengths of 400 and 450 nm is greater than 0.5 times the slope of the unused film, it is highly likely that the film blocking substance is calcium fluoride, as shown in FIG. In this case, the arithmetic unit 35 transmits information notifying that the membrane blocking substance is calcium fluoride to the control unit 5 (step S11), returns to the process of step S1, and repeats the process from step S1.

When the control device 5 is notified by the arithmetic device 35 that the membrane blocking substance is calcium fluoride, the control device 5 injects an acidic chemical solution to clean the separation membrane (monitoring separation membrane) when cleaning the separation membrane. . Also, in order to suppress the occurrence of membrane clogging, the dosage of the scale dispersant is increased. The control device 5 may control the pH by injecting an acidic chemical solution or an alkaline chemical solution to suppress the occurrence of membrane clogging.

In this example, an example for identifying membrane blocking substances when the assumed substances are calcium carbonate, calcium fluoride, silica, and biofouling is shown. If the hypothetical substances other than those mentioned above are conceivable, the reflection intensity for each of four or more wavelengths of light is measured in advance for each substance, and the total reflection intensity for each substance and the specific wavelength are calculated as shown in FIG. The inclination of the light may be obtained and used to identify the membrane blocking substance. For example, when barium salts, calcium salts, magnesium salts, metal complexes, etc. are considered as assumed substances, the reflection intensities of light of four or more wavelengths in the visible light of these substances are measured in advance, and as shown in FIG. Then, the sum of the reflection intensities for each substance and the gradient for light of a specific wavelength may be obtained and used to identify the film blocking substance.

Comparative example

In this comparative example, the results of comparing the method for specifying a membrane blocking substance shown in the above example and the method for specifying a membrane blocking substance shown in Patent Document 2 above will be described.

FIG. 9 is a table showing the parameters used in the analysis method of the membrane blocking substance of the comparative example obtained from the spectral data shown in FIGS.

FIG. 9 shows the above implementation for red (R: light with a wavelength of 466 nm), green (G: light with a wavelength of 532 nm), and blue (B: light with a wavelength of 630 nm), which are the three primary colors of light measurable by the color sensor used in Patent Document 2. The inclination obtained from the measurement data for each hypothetical substance shown in the example is shown.

As shown in FIG. 9, when comparing the slopes of the unused film and assumed material at wavelengths of 466 nm, 532 nm, and 630 nm, it can be seen that the slopes of the unused film and calcium fluoride are almost the same. In addition, it can be seen that the slopes of calcium carbonate, silica and biofouling are almost the same.

Therefore, when calcium carbonate, calcium fluoride, silica, and biofouling are assumed substances, it is difficult to distinguish between unused membranes and calcium fluoride by the method for identifying membrane-blocking substances disclosed in Patent Document 2. and it is difficult to distinguish between calcium carbonate, silica and biofouling. That is, when calcium carbonate, calcium fluoride, silica, and biofouling are considered as assumed substances, it can be seen that the membrane blocking substance cannot be specified by the method for specifying a membrane blocking substance disclosed in Patent Document 2.

On the other hand, in the present invention, as shown in the above examples, it is possible to distinguish these substances, and by selecting an appropriate chemical solution based on the identified membrane clogging substance, the separation membrane can be washed. or suppress the occurrence of membrane occlusion.

Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the above embodiments. Various modifications can be made to the configuration and details of the present invention within the scope of the present invention that a person skilled in the art can understand.

Claims

Irradiate visible light to the monitoring separation membrane through which the test water is passed,
measuring the reflection intensity of the visible light reflected by the monitoring separation film with a visible light spectrophotometer;
A method for analyzing a membrane blocking substance, wherein the membrane blocking substance is identified based on the measured reflection intensity of the visible light.
The method for analyzing a membrane-occluding substance according to claim 1, wherein the membrane-occluding substance is identified based on the reflection intensities of light of four or more wavelengths in the visible light region of 400 nm to 800 nm.
The occlusive substance of the film is determined based on the reflection intensity of light of at least one or more wavelengths measured in each of the visible light regions of 400 nm to 450 nm, 450 nm to 500 nm, 600 nm to 700 nm, and 700 nm to 800 nm. 3. The method for analyzing a membrane-obstructing substance according to claim 2, wherein the substance is identified.
measuring the reflection intensity of an unused membrane that is the unused monitoring separation membrane and an assumed substance that is an assumed blocking substance of the membrane;
calculating a first slope, which is the difference in the reflection intensity with respect to the difference in the wavelength light in the unused film and the assumed material;
storing the first slope of the virgin film and the assumed material and the reflection intensity of the virgin film for light with a wavelength of 400 to 450 nm or 700 to 800 nm;
measuring the reflection intensity of the visible light from the monitored membrane, which is the monitoring separation membrane through which the test water is passed;
determining that the monitored film is clogged when the reflection intensity of the monitored film in the wavelength light of 400 to 450 nm or 700 to 800 nm is smaller than the reflection intensity of the unused film;
calculating a second slope, which is the difference in the reflection intensity with respect to the difference in the wavelength light, in the film to be monitored;
4. The membrane according to any one of claims 1 to 3, wherein a blockage substance in the membrane blocking the monitored membrane is identified by comparing the first slope and the second slope. Method for analyzing occlusive substances.
a monitoring separation membrane through which test water is passed;
a visible light spectrophotometer for irradiating the monitoring separation film with visible light and measuring the reflection intensity of the visible light reflected by the monitoring separation film;
a computing device that identifies a film blocking substance based on the measured reflection intensity of the visible light;
Membrane blockage substance analyzer.
The computing device is
6. The apparatus for analyzing membrane-occluding substances according to claim 5, wherein said membrane-occluding substances are identified based on said reflection intensities of light of four or more wavelengths in a visible light region of 400 nm to 800 nm.
The computing device is
The membrane blocking substance is identified based on the reflection intensity of light of at least one or more wavelengths measured in each of the visible light regions of 400 nm to 450 nm, 450 nm to 500 nm, 600 nm to 700 nm, and 700 nm to 800 nm. 7. The apparatus for analyzing a membrane-occlusive substance according to claim 6.
The computing device is
From the reflection intensity of the unused membrane that is the unused separation membrane for monitoring and the assumed substance that is the assumed blocking substance of the membrane measured by the visible light spectrophotometer, the unused membrane and the assumed substance , the first slope, which is the difference in the reflection intensity with respect to the difference in the wavelength light, is calculated, and the first slope of the unused film and the assumed material and the wavelength light of 400 to 450 nm or 700 to 800 nm storing the reflection intensity of the virgin film in
Light with a wavelength of 400 to 450 nm or 700 to 800 nm, based on the reflected intensity of the visible light of the monitored membrane, which is the monitoring separation membrane through which the test water is passed, measured by the visible light spectrophotometer. and determining that the film to be monitored is blocked when the reflection intensity of the film to be monitored is smaller than the reflection intensity of the unused film, and the reflection of the difference in wavelength light from the film to be monitored Calculating a second slope, which is a difference in intensity, and comparing the first slope and the second slope to identify the blocking substance of the membrane that blocks the monitored membrane. Item 8. The apparatus for analyzing a membrane blocking substance according to any one of Items 5 to 7.
The water to be treated is separated into permeated water and concentrated water by a separation membrane,
Part of the concentrated water is passed through a monitoring separation membrane as test water,
irradiating the monitoring separation membrane through which the test water is passed with visible light;
measuring the reflection intensity of the visible light reflected by the monitoring separation film with a visible light spectrophotometer;
identifying a film blocking substance that blocks the separation film based on the measured reflection intensity of the visible light;
A chemical injection control method for a separation membrane, comprising injecting a chemical solution for dissolving and removing a specified membrane clogging substance or a chemical solution for suppressing membrane clogging by the specified membrane clogging substance into a water flow line of the separation membrane.
A membrane separation device equipped with a separation membrane that separates water to be treated into permeated water and concentrated water;
a monitoring separation membrane through which part of the concentrated water is passed as test water;
a visible light spectrophotometer for irradiating the monitoring separation membrane through which the test water is passed with visible light and measuring the reflection intensity of the visible light reflected by the monitoring separation membrane;
an arithmetic device for identifying a film blocking substance that blocks the separation film based on the measured reflection intensity of the visible light;
a control device for injecting a chemical solution for dissolving and removing the specified membrane clogging substance or a chemical solution for suppressing membrane clogging by the specified membrane clogging substance into the water flow line of the separation membrane;
A chemical dosing control device for a separation membrane having