JP2013223835A - Method for evaluating membrane fouling and method for washing separation membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain information useful for evaluation of membrane fouling accumulated on a separation membrane.SOLUTION: There is provided a method for evaluating membrane fouling 90 accumulated on the principal surface 23f of a separation membrane 23 that performs membrane separation of a supplied fluid to generate a permeating fluid. The evaluation method includes: an image acquiring step of acquiring the laser light reflection image of the membrane fouling 90 and the stained image of the membrane fouling 90, using the membrane fouling 90 accumulated on the principal surface of a separation membrane for fouling evaluation which performs membrane separation of a sampling fluid flowing while being branched from the separation membrane 23 or a supply fluid as an evaluation object; and a component evaluating step of acquiring information W about the total amount of the membrane fouling 90 from the laser light reflection image and acquires information C about the amount of a part of the components among the plurality of components configuring the membrane fouling 90 from the stained image.

Description

  The present invention relates to a method for evaluating membrane fouling deposited on the main surface of a separation membrane that separates a supply fluid to generate a permeated fluid. The present invention also relates to a separation membrane cleaning method using this evaluation method.

  The membrane separation action of the separation membrane is used in various fields. For example, composite reverse osmosis membranes are used for seawater desalination, wastewater treatment, and the like. When fluid containing foulants such as inorganic substances and fungi permeates the separation membrane, the foulants are deposited on the surface of the separation membrane (hereinafter sometimes referred to as membrane surface) to form membrane fouling, and the membrane of the separation membrane Separation effect decreases. For this reason, the film surface is appropriately cleaned. As a method for cleaning the membrane surface, a chemical cleaning method using a cleaning agent containing a disinfectant such as acid, alkali or chlorine, or a flushing cleaning method or a reverse cleaning method in which a supply fluid is flowed in a direction opposite to the direction during normal operation, etc. These physical cleaning methods are mentioned.

  From the viewpoint of suppressing deterioration of the separation membrane (that is, from the viewpoint of extending the life of the separation membrane and maintaining the membrane separation action), it is preferable to carry out the above washing without excess or deficiency. Conventionally, the timing of cleaning has been determined based on experience, quality of the supplied fluid, fluid data before and after membrane separation (for example, flow rate, content of foreign matter in the fluid), and the like. However, from the viewpoint of suppressing deterioration of the separation membrane, it is desirable to evaluate membrane fouling directly and objectively regardless of experience.

  Patent Documents 1 to 4 describe methods for evaluating specific components in membrane fouling. Patent Document 1 describes that a biofilm is evaluated based on transmitted light of a laser beam. Patent Document 2 describes that a biofilm is evaluated based on a fluorescence image obtained by a confocal optical microscope and a computer. Patent Document 3 describes that a biofilm is evaluated by an ATP (adenosine triphosphate) measurement method. Patent Document 4 describes that a scale is evaluated based on an image derived from a reflected beam obtained by a microscope and a camera.

JP 2008-107330 A JP 2005-525551 A International Publication No. 2008/038575 Special table 2009-524521

  Patent Documents 1 to 3 describe a biofilm evaluation method, and Patent Document 4 describes a scale evaluation method. However, membrane fouling often consists of a plurality of types of components, and the appropriate cleaning method differs depending on the types of components. Therefore, in order to appropriately select the cleaning mode (timing, method) of the separation membrane, it is desirable that the constituent elements of the membrane fouling can be grasped by dividing into different categories of appropriate cleaning methods. Therefore, an object of the present invention is to provide a membrane fouling evaluation method suitable for appropriate selection of a cleaning method, and a separation membrane cleaning method using the same.

The present invention
A method for evaluating membrane fouling deposited on the main surface of a separation membrane that separates a supply fluid to generate a permeated fluid,
The membrane fouling deposited on the main surface of the separation membrane for fouling evaluation for membrane separation of the separation fluid flowing from the separation membrane or the supply fluid is evaluated, and the laser light reflection image of the membrane fouling, An image acquisition step of acquiring a stained image of membrane fouling;
Component evaluation for acquiring information W regarding the total amount of the film fouling from the laser light reflection image and acquiring information C regarding the amount of some of the plurality of components constituting the film fouling from the stained image And a method for evaluating membrane fouling.

The present invention also provides:
A membrane fouling evaluation step for carrying out the above-described membrane fouling evaluation method;
A cleaning method designating step of designating a cleaning method determined by the information W and the information C;
And a cleaning step of cleaning the separation membrane by the cleaning method.

  In the method for evaluating membrane fouling according to the present invention, information W relating to the total amount of membrane fouling is obtained, and information C relating to the amount of some of the components constituting the membrane fouling is obtained. Information W and information C are useful for evaluation of membrane fouling for designating an appropriate cleaning method, and further for cleaning the separation membrane by an appropriate cleaning method.

Cross section of separation membrane Cross section of separation membrane with deposited membrane fouling Configuration diagram of confocal optical microscope Configuration diagram of membrane separator Perspective view of submodule Sectional drawing of the submodule shown to FIG. 5A Flow chart showing an example of a cleaning method for a membrane separator Flow chart showing another example of the cleaning method of the membrane separator Stained image of sample A Laser light reflection image of sample A Stained image of sample B Laser light reflection image of sample B

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description relates to an example of the present invention, and the present invention is not limited to the following embodiment.

(First embodiment)
The separation membrane 23 shown in FIG. 1 has a function of generating a permeated fluid by membrane separation of the supplied fluid (a general term for an operation of filtering an object by passing the fluid through a partition wall (membrane) having selectivity). Yes. The separation membrane 23 includes a liquid supply fluid (brine, seawater, drainage, irrigation water, etc.) capable of membrane separation and a gas (vapor) supply fluid capable of membrane separation. Specific examples of the separation membrane 23 include a reverse osmosis (RO) membrane, a nanofiltration (NF) membrane, an ultrafiltration membrane (UF) membrane, and a microfiltration (MF) membrane. Depending on the foulant contained in the supply fluid, as shown in FIG. 2, a membrane fouling 90 is deposited on the main surface 23f of the separation membrane 23 obtained by membrane separation of the supply fluid.

  Examples of the foulant forming the membrane fouling 90 include hardly soluble inorganic substances (metal oxides such as iron and manganese, calcium carbonate, silica, etc.), bacteria (microorganisms, etc.), and organic substances (oil, residual polymer, etc.). Can be mentioned. The hardly soluble inorganic substance is a foulant constituting the scale. Bacteria are foulants that make up biofilms. Both scales and biofilms are a type of membrane fouling 90, and in many cases membrane fouling 90 includes both scale and biofilm. Biofilm is a membrane fouling that requires special attention because it particularly degrades the membrane separation action of the separation membrane.

  The evaluation of the membrane fouling 90 deposited on the main surface 23f of the separation membrane 23 can be performed by an evaluation method using the membrane fouling 90 as a measurement target (directly evaluating the membrane fouling 90). Further, the separation membrane 23 can be cleaned by a cleaning method performed based on this evaluation method. For example, the evaluation method includes a membrane separation step, an image acquisition step, and a component evaluation step, and the cleaning method includes a membrane fouling evaluation step for performing the evaluation method, and a cleaning method designation step. And a washing step. Hereinafter, an example of each step of the membrane separation step, the image acquisition step, the component evaluation step, the cleaning method designation step, and the cleaning step will be described.

  In the membrane separation step, part or all of the supply fluid permeates through the separation membrane 23. In the membrane separation step, the membrane fouling 90 corresponding to the foulant and the like contained in the supply fluid is deposited on the main surface (surface to which the supply fluid is supplied) 23f of the separation membrane 23.

  In the image acquisition step, the film fouling 90 deposited on the main surface 23f of the separation membrane 23 is used as an evaluation target, and a laser light reflection image of the film fouling 90 and a stained image of the film fouling 90 are acquired.

  The laser light reflection image of the film fouling 90 is an image representing all components constituting the film fouling 90 and is acquired by reflecting the laser light emitted from the light source on the film fouling 90. When a laser beam reflection image is acquired by a normal measuring instrument, monochromatic light having a visible wavelength is used as the laser beam. From the viewpoint of increasing the resolution of the reflected laser beam image, the wavelength range of the laser beam is preferably a short wavelength side range in the visible range, for example, a range of 400 to 600 nm.

  The stained image of the membrane fouling 90 is an image representing a part of a plurality of components constituting the membrane fouling 90, and a stain that stains the part of the component is brought into contact with the membrane fouling 90. Get after.

  In this embodiment, a staining agent (typically a fluorescent staining agent) for specifically detecting bacteria is used, and a stained image (typically a fluorescent staining image) representing a biofilm is acquired. Examples of stains for specifically detecting bacteria include SYTO9, 2,3,5-triphenyltetrazolium chloride, 4 ′, 6-diamidino-2-phenylindole (DAPI (4 ′, 6-diamidino-2- phenylindole)) and propidium iodide (PI). Among these stains, SYTO9 is a stain for specifically detecting viable bacteria, and propidium iodide is a stain for specifically detecting dead bacteria.

  However, in place of the above-mentioned staining agent, by adding a saccharide-binding reagent that can stain polysaccharides produced by bacteria, or an enzyme substrate that reacts with bacteria, a stained image representing a biofilm is obtained. May be. Further, usable dyeing agents are not limited to the above. For example, a staining image (eg, toluidine blue, alcian blue (for example, manufactured by Wako Pure Chemical Industries, Ltd.)) for specifically detecting an organic substance may be used to obtain a stained image representing the organic substance, and the inorganic substance may be specific. A staining image representing a scale may be obtained using a staining agent (such as a dye exhibiting adsorptivity to individual inorganic substances). A plurality of types of staining agents may be used in combination.

  A publicly known microscope is mentioned as a measuring instrument for acquiring a laser beam reflected image and a dyed image. As a suitable measuring instrument for acquiring a laser beam reflection image and a stained image, a confocal optical microscope (confocal laser microscope) can be mentioned. According to the confocal optical microscope, a laser light reflection image and a stained image can be acquired as a three-dimensional image. Obtaining a three-dimensional image is effective in that the thickness information of the laser light reflected image and the stained image can be used in the component evaluation step.

  An example of the confocal optical microscope will be described with reference to FIG. The confocal optical microscope 8 shown in FIG. 3 includes an image analysis device 81, a light receiving element 82, a pinhole panel 83, an imaging lens 84, a half mirror 85, an objective lens 86, and a light source 87.

  In the case of acquiring a laser light reflection image, laser light is irradiated from the light source 87 toward the half mirror 85. A part of the laser light reaching the half mirror 85 is reflected and travels toward the objective lens 86. The laser light reaching the objective lens 86 is refracted and reaches the separation film 23 (more precisely, the film fouling 90 on the main surface 23f) in a condensed state. The laser light that reaches the separation film 23 is reflected and reaches the light receiving element 82 through the objective lens 86, the half mirror 85, the imaging lens 84, and the pinhole panel 83.

  In the case of acquiring a fluorescent dyed image, the fluorescence derived from the fluorescent dye bonded to the film fouling 90 reaches the light receiving element 82 via the objective lens 86, the half mirror 85, the imaging lens 84 and the pinhole panel 83. .

  When some components constituting the film fouling 90 are dyed, the reflected laser light image may be affected. Therefore, in the image acquisition step, it is preferable to acquire a dyed image by bringing a dyeing agent into contact with the film fouling 90 after acquiring a laser light reflection image. If membrane separation by the separation membrane 23 is continued even after the image acquisition step is completed, the unstained membrane fouling 90 is deposited on the stained membrane fouling 90. This deposition makes it easy to acquire a reflected laser light image again.

  However, the separation film for acquiring the laser light reflection image and the separation film for acquiring the dyed image are arranged in parallel to the flow of the supply fluid, so that the laser light reflection image and the dyed image are simultaneously obtained. And may be acquired. According to this aspect, the period required for the image acquisition step can be shortened.

  Further, when the laser light reflection image and the stained image are acquired from the same separation film, the region for acquiring the laser light reflection image and the region for acquiring the staining image in the separation film 23 are different even if they are the same. It may be.

  In the component evaluation step, information W regarding the total amount of the film fouling 90 is acquired from the laser light reflection image, and information C regarding the amount of some of the components constituting the film fouling 90 is acquired from the stained image. To do.

  Information W and information C are information for specifying the total amount of the membrane fouling 90 and the amount of some components, respectively, and are typically digitized information. This numerical value indicates, for example, the volume of all or some of the components constituting the membrane fouling 90. However, the information W and the information C are not limited to numerical values. For example, a two-dimensional map that displays a section where the target component exists, or a visual that displays the volume of the target component in gray scale or color scale. The information may be converted into information.

  Information W and information C are acquired, for example, by performing image analysis on a laser light reflection image and a stained image, respectively. A known image analysis device can be used for image analysis. The image analysis apparatus may be mounted inside the measuring instrument, or may be connected to the measuring instrument by wire or wirelessly. The image analysis device 81 in FIG. 3 is an example of an image analysis device mounted inside the measuring instrument, and is connected to the light receiving element 82.

  In some cases, it may be effective to obtain information CR regarding the amount of the remaining components excluding the amount of some of the components constituting the membrane fouling 90 from the information W and the information C. For example, in a situation where most of the membrane fouling 90 is expected to be composed of a biofilm and a scale, if the information C is information representing the amount of biofilm, the acquired information CR is substantially It can be handled as information representing the amount of scale.

  When two types of stains are used in the image acquisition step, that is, the first stain and the second stain, information c1 and second information on the amount of the first component dyed by the first stain in the component evaluation step. Information C including information c2 relating to the amount of the second component dyed by the staining agent is acquired. For example, in the image acquisition step, when a first stain for specifically detecting viable bacteria and a second stain for specifically detecting dead bacteria are used in combination, the information c1 is bio-derived from the live bacteria. Information c2 can be handled as an amount representing a biofilm derived from killed bacteria as an amount representing a film. In general, when n types of stains (n is an integer) are used in the image acquisition step, information (information c1, information c2) regarding the amount of each component dyed by each stain in the component evaluation step. ,... Information C including information cn) is acquired.

  In the cleaning method designation step, a cleaning method determined by information W and information C is designated.

  When the information W and the information C are digitized information, an output value obtained by using the information W and the information C as input values can be calculated, and a cleaning method can be determined by the output values. For example, by comparing the information W and the information C, calculating the ratio of the volume of the stained image to the volume of the laser light reflected image, the difference between the volume of the laser light reflected image and the volume of the stained image, etc. It is effective to specify. Further, by comparing the information C with the information CR and calculating the difference between the volume of the stained image and the volume of the portion other than the stained image in the laser light reflected image, the magnitude relationship between the two may be determined. When the information W and the information C are visualized information, the information W and the information C may be visually compared to determine the magnitude relationship between the volume of the laser light reflected image and the volume of the stained image.

  In the present embodiment, when an output value indicating that the component to be removed in the membrane fouling 90 is a biofilm is calculated, a cleaning method (for example, an alkali cleaning method) that can suitably remove the biofilm is selected, When an output value indicating that the component to be removed is a scale is calculated, a cleaning method (for example, an acid cleaning method) that can suitably remove the scale is selected.

  However, the cleaning method designation step is not limited to the aspect of the present embodiment. For example, when an output value indicating that the component to be removed in the membrane fouling 90 is a biofilm is calculated, an output value indicating that the component to be removed is a biofilm derived from living bacteria is calculated. Sometimes a cleaning method (for example, a sterilization cleaning method) that can suitably remove a biofilm derived from live bacteria is selected, and when an output value indicating that the component to be removed is a biofilm derived from killed bacteria is calculated, A mode in which a cleaning method (for example, a flushing cleaning method) capable of suitably removing the derived biofilm may be employed. In addition, when it is understood from the information W that the membrane fouling 90 is not deposited to the extent that the separation membrane 23 needs to be cleaned, a mode in which the cleaning step is not performed may be adopted. In this case, the cleaning method designating step is performed as a step of designating the cleaning method determined by the information W and the information C or determining not to perform the cleaning.

  Examples of the cleaning method of the separation membrane 23 that can suitably remove the biofilm include an alkali cleaning method, a sterilizing cleaning method, and a physical cleaning method. An example of a cleaning method for the separation membrane 23 that can suitably remove the scale is an acid cleaning method. Examples of the cleaning method for the separation membrane 23 that can remove the biofilm derived from live bacteria particularly preferably include a sterilization cleaning method. Examples of the cleaning method for the separation membrane 23 that can particularly suitably remove the biofilm derived from dead bacteria include a physical cleaning method.

  The chemical used in the above alkaline cleaning method is sodium hydroxide or the like, the chemical used in the acid cleaning method is citric acid, hydrochloric acid or the like, and the chemical used in the sterilization cleaning method is chlorine or the like. In the alkali cleaning method, the acid cleaning method, and the sterilization cleaning method, the above chemicals are supplied to the object to be cleaned (separation membrane 23). Examples of the physical cleaning method include a flushing cleaning method and a reverse cleaning method.

  In the cleaning step, the separation membrane 23 is cleaned by the cleaning method specified in the cleaning method specifying step.

  Hereinafter, the cleaning method of the separation membrane 23 in the present embodiment will be further described with specific examples (first specific example to third specific example).

  In the first specific example, first, the membrane fouling 90 is deposited on the main surface 23f of the separation membrane 23 in the membrane separation step. Next, in the image acquisition step, a laser light reflection image of the membrane fouling 90 is acquired, and a stained image representing a biofilm in the membrane fouling 90 is acquired. Next, in the component evaluation step, information W representing the total volume of the membrane fouling 90 and information C representing the volume of the biofilm in the membrane fouling 90 are acquired from the laser light reflection image and the stained image, and the information W and the information are obtained. Information CR estimated to represent the volume of the scale is obtained from C. Next, in the cleaning method designation step, the magnitude relationship between the volume of the biofilm and the volume of the scale is determined from the information C and the information CR. When the biofilm volume is determined to be greater than or equal to the scale volume, the alkali cleaning method is selected, and when the biofilm volume is determined to be less than the scale volume, the acid cleaning method is selected. In the cleaning step, the separation membrane 23 is cleaned by the cleaning method selected in the cleaning method designating step.

  In the first specific example, in the component evaluation step, information CR (volume of the scale) regarding the amount of the remaining components excluding the amount of some of the plurality of components is expressed as information W (total volume of the membrane fouling 90). And from the information C (volume of biofilm), and in the cleaning method designation step, the cleaning method is selected and designated from the acid cleaning method and the alkali cleaning method by the information C and information CR. Therefore, in the first specific example, it is possible to selectively perform either washing suitable for removing the biofilm or washing suitable for removing the scale.

  In the second specific example, the same membrane separation step and image acquisition step as those in the first specific example are performed. Next, in the component evaluation step, information W representing the entire volume of the membrane fouling 90 and information C representing the volume of the biofilm in the membrane fouling 90 are acquired from the laser light reflection image and the stained image. Next, in the cleaning method designation step, by comparing the information W and the information C, the ratio C / W of the volume of the stained image representing the biofilm to the volume of the reflected laser light image is calculated as an output value. Subsequently, for example, when the ratio C / W is 0.05 or more, the alkali cleaning method is selected, and when the ratio C / W is less than 0.05, the acid cleaning method is selected. In the cleaning step, the separation membrane 23 is cleaned by the cleaning method selected in the cleaning method designating step.

  According to the second specific example, either the washing suitable for removing the biofilm or the washing suitable for removing the scale can be selectively performed.

  In the third specific example, the same membrane separation step as in the first specific example is performed. Next, in the image acquisition step, a laser light reflection image of the membrane fouling 90 is acquired, a first stained image representing a biofilm derived from live bacteria in the membrane fouling 90, and a dead bacteria-derived bio in the membrane fouling 90. A second stained image representing the film is obtained. Next, in the component evaluation step, from the laser light reflection image, the first stained image, and the second stained image, information W representing the entire volume of the membrane fouling 90, and the volume of the biofilm derived from viable bacteria in the membrane fouling 90 The information c1 that represents the volume of the biofilm derived from dead bacteria in the membrane fouling 90 and the information c2 that represents the volume of the scale are obtained from the information W, the information c1, and the information c2. Next, in the cleaning method designation step, from the information c1, the information c2 and the information CR, the volume of the biofilm (the sum of the volume of the biofilm derived from living bacteria and the volume of the biofilm derived from dead bacteria) and the volume of the scale are calculated. Determine the magnitude relationship. If the volume of the biofilm is determined to be greater than or equal to the volume of the scale, the size relationship between the volume of the biofilm derived from viable bacteria and the volume of the biofilm derived from dead bacteria is determined, and the volume of the biofilm derived from live bacteria is dead. When it is determined that the volume of the biofilm derived from the bacteria is equal to or greater than the volume of the biofilm derived from bacteria, the flushing cleaning method is selected when the volume of the biofilm derived from live bacteria is determined to be less than the volume of the biofilm derived from dead bacteria. If the biofilm volume is determined to be less than the scale volume, an acid cleaning method is selected. In the cleaning step, the separation membrane 23 is cleaned by the cleaning method selected in the cleaning method designating step.

  In the third specific example, in the cleaning method designation step, the cleaning method is selected and designated from an acid cleaning method, a sterilization cleaning method, and a flushing cleaning method. According to the third specific example, either washing suitable for removing the biofilm or washing suitable for removing the scale can be selectively performed. Further, according to the third specific example, the washing when the biofilm is to be removed is selected from washing particularly suitable for removing biofilm derived from live bacteria and washing particularly suitable for removing biofilm derived from dead bacteria. Can be implemented.

(Second Embodiment)
Evaluation of membrane fouling deposited on the main surface of the separation membrane can also be performed by an evaluation method for indirectly evaluating the membrane fouling. Further, the separation membrane can be cleaned by a cleaning method that is performed based on the evaluation result of the evaluation method. Hereinafter, as an embodiment of an indirect membrane fouling evaluation method and a separation membrane cleaning method using the same, a membrane fouling evaluation method for a membrane separation device and a membrane separation device cleaning method will be described. In addition, in the following description, the description which overlaps with 1st Embodiment may be abbreviate | omitted.

  First, the configuration of the membrane separation apparatus in the present embodiment will be described.

The membrane separation device 110 shown in FIG. 4 has a function of generating a permeated fluid by membrane-separating the supply fluid F (fluid corresponding to the supply fluid of the first embodiment). The membrane separation apparatus 110 includes a separation membrane module 101 for providing the function and a submodule 102 for indirectly grasping membrane fouling deposited in the separation membrane module 101. In the membrane separator 110, the separation membrane module 101 is connected to the downstream end of the first flow path 111, and the submodule 102 is the downstream end of the second flow path 112 that is a branch path branched from the first flow path 111. , A pressure pump 106 is provided in the first flow path 111, and a valve (flow rate adjusting valve) 105 is provided in the second flow path 112, so that most of the supply fluid F is separated. The remaining portion (hereinafter referred to as sampling fluid S) that is guided to the membrane module 101 and flows from the supply fluid F is guided to the submodule 102. In this embodiment, since the separation membrane module 101 and the submodule 102 are cross-flow type modules, the supply fluid F guided to the separation membrane module 101 is separated into the permeation fluid T ₁ and the concentrated fluid C _1. The sampling fluid S guided to the module 102 is separated into a permeating fluid T ₂ and a concentrated fluid C ₂ .

  The separation membrane module 101 in this embodiment is a spiral type module having the same type of separation membrane as the separation membrane 23. However, the separation membrane module may be a flat membrane type such as a frame and plate type, a tubular type such as a tubular type, a hollow fiber type, or a pleated type. Further, the separation membrane module may be a module of a system other than the cross flow system, such as a total filtration system.

In the submodule 102 according to the present embodiment, as shown in FIGS. 5A and 5B, the permeation side flow path material 124, the fouling evaluation separation film 123, and the deposition material 122 are accommodated in the container 130 in a state of being laminated in this order. ing. The container 130 is provided with an inflow port 127, a concentrated fluid outflow port 128, and a permeated fluid outflow port 129, and the inflow port 127 is connected to the second flow path 112. As a result, the sampling fluid S flows into the container 130 from the inflow port 127, and a part of the sampling fluid S passes through the supply side channel 161 facing the deposition material 122 and flows out from the concentrated fluid outflow port 128 as the concentrated fluid C _2. , and it can flow out through the permeation-side passage 162 which portion of the other facing the fouling evaluation separation film 123 on the permeation-side passage material 124 passes through as permeate T _2. For convenience of viewing the drawings, film fouling is omitted in FIGS. 5A and 5B.

  From the viewpoint of improving the reproducibility of the membrane fouling of the separation membrane module 101 by the submodule 102, the separation membrane 123 for fouling evaluation in the present embodiment is made of the same material as the material of the separation membrane in the separation membrane module 101. ing. However, the fouling evaluation separation membrane 123 may be made of a material different from the material of the separation membrane in the separation membrane module 101. Of the membrane surface 123f facing the supply-side channel 161 and the membrane back surface 123b facing the permeation-side channel 162 in the fouling evaluation separation membrane 123, the surface on the supply side of the sampling fluid S, and the membrane The film surface 123f, which is a surface on which fouling is more easily deposited, corresponds to the “main surface” in the claims.

  The deposition material 122 in this embodiment is a resin-made lattice net provided so as to be in contact with the film surface 123f. The deposition material 122 temporarily dams the flow of the sampling fluid S and causes the flow of the sampling fluid S to stay or turbulence in the submodule 102 to promote deposition of film fouling on the film surface 123f. However, the deposition material may be configured by a group of convex portions provided discretely, or may be configured by another material (rubber, metal, etc.). Further, the deposition material may be omitted.

The permeate-side channel material 124 is a resin-made lattice net provided so as to be in contact with the film back surface 123b. The permeate-side flow path member 124 is a member for guiding the permeate fluid T ₂ to the outflow port 129 without stagnation. In this embodiment, the permeation-side flow path member 124 and the deposition material 122 are made of the same material and have the same shape, but may be made of different materials and have different shapes. It may be.

  The container 130 includes a container main body 131 having an opening 150 and a lid 132 that is detachably attached to the opening 150. The opening 150 is provided at a position facing the membrane surface 123f with the supply-side flow channel 161 interposed therebetween so that the membrane surface 123f can be measured (observed) when the lid 132 is removed.

  In the present embodiment, the container 130 is configured so as to ensure pressure resistance while having a mode in which the container main body 131 is closed by a detachable lid 132. Specifically, when the female screw portion 141 formed in the opening 150 and the male screw portion 142 formed in the lid portion 132 are screwed together, the lid portion 132 can be screwed into the opening portion 150. ing. In addition, although the container 130 in this embodiment is comprised with the metal (stainless steel), all or one part may be comprised with the transparent member (pressure | voltage resistant glass etc.). In this case, since the separation film 123 for fouling evaluation can be observed through the transparent member, the opening 150 and the lid 132 can be omitted.

  In this embodiment, since the same type of module is used as both the separation membrane module 101 and the submodule 102, the reproducibility of the membrane fouling of the separation membrane module 101 by the submodule 102 is high. However, different types of modules may be used as both modules.

  In the present embodiment, a confocal optical microscope 108 is provided in the submodule 102. An example of the configuration of the confocal optical microscope 108 is the same as the example described with reference to FIG. However, another measuring device may be used instead of the confocal optical microscope 108.

  In the present embodiment, the stain tank 104 is connected to the branch path of the second flow path 112. The stain tank 104 stores a stain for specifically detecting bacteria, and the stain can be supplied to the submodule 102 by opening the valve 107. However, any of the stains described in the first embodiment may be stored in the stain tank 104. In FIG. 4, there is one staining agent tank 104, but when a plurality of types of staining agents are used, a plurality of staining agent tanks may be provided.

  Next, a membrane fouling evaluation method of the membrane separation device 110 and a cleaning method of the membrane separation device 110 will be described. The measurement target in the membrane fouling evaluation method of the membrane separation apparatus 110 is a membrane fouling deposited on the main surface 123f of the separation membrane 123 for fouling evaluation, and the cleaning target is for the separation membrane and the fouling evaluation in the separation membrane module 101. This is the separation membrane 123. The membrane fouling evaluation method of the membrane separation apparatus 110 in this embodiment includes a membrane separation step, an image acquisition step, and a component evaluation step. The method for cleaning the membrane separation device 110 in the present embodiment includes a membrane fouling evaluation step for performing the evaluation method, a cleaning method designating step, and a cleaning step. Hereinafter, an example of each step of the membrane separation step, the image acquisition step, the component evaluation step, the cleaning method designation step, and the cleaning step will be described.

  In the membrane separation step, part of the supply fluid F passes through the separation membrane in the separation membrane module 101, and part of the sampling fluid S passes through the separation membrane 123 for fouling evaluation in the submodule 102. By the membrane separation step, membrane fouling occurs on the main surface of the separation membrane (surface to which the supply fluid F is supplied) in the separation membrane module 101 and the main surface (membrane surface 123f) of the separation membrane 123 for fouling evaluation in the submodule 102. Accumulate.

  The rate at which membrane fouling is deposited on the main surface of the separation membrane and the membrane surface 123f in the separation membrane module 101 differs depending on the application of the membrane separation device 110 and the like. When the membrane separation device 110 is used as a seawater desalination device, pretreated seawater flows from the upstream side of the pressure pump 106. Here, the pretreatment is a sand filtration treatment, a membrane treatment using a UF membrane, an MF membrane, or the like. If seawater pretreatment is appropriate, the rate of scale deposition is slow and the scale may not be substantially formed. If seawater pretreatment is inadequate, the scale deposition rate will increase. Since the nutrient source of biofilm is organic matter, the deposition rate of biofilm varies greatly depending on the amount and type of organic matter contained in seawater. If the feed fluid is seawater, the seawater is properly pretreated, the scale deposition rate is slow, and the seawater has a general amount and type of organic matter, the appropriate interval for the image acquisition step is For example, 2 to 3 months.

  In the membrane separation step of the present embodiment, the valve 105 is set so that the difference between the pressure of the sampling fluid S supplied to the submodule 102 and the pressure of the supply fluid F supplied to the separation membrane module 101 is a predetermined value or less. Adjust to. Thereby, the reproducibility of the membrane fouling of the separation membrane module 101 by the submodule 102 is improved.

  In the image acquisition step, the film fouling deposited on the membrane surface 123f (main surface) of the fouling evaluation separation membrane 123 is evaluated, and the laser light reflection image of the film fouling and the stained image of the film fouling are obtained. get. Specifically, first, the valve 105 is closed. Next, the lid 132 is removed from the opening 150. Next, the confocal optical microscope 108 is fixed at a position suitable for measurement of the film surface 123f. Next, a laser beam reflection image of the film fouling deposited on the film surface 123f is acquired. Next, by opening the valve 107, the staining agent is injected from the staining agent tank 104 into the submodule 102, and the staining agent is brought into contact with the membrane fouling. Next, a stained image of membrane fouling is acquired. In the present embodiment, a stained image representing a biofilm in membrane fouling is obtained by using a stain for specifically detecting bacteria.

  In the component evaluation step, information W regarding the total amount of film fouling is acquired from the laser light reflection image, and information C regarding the amount of biofilm is acquired from the stained image. In the present embodiment, the information W and the information C are acquired by performing image analysis on the laser light reflection image and the stained image using an image analysis device mounted on the confocal optical microscope 108, respectively. In the present embodiment, the information W and the information C are acquired as digitized information, and the information CR is acquired from the information W and the information C and handled as information indicating the amount related to the scale.

  In the cleaning method designation step, an output value obtained by using the information W, the information C, and the information CR as input values is calculated, and the cleaning method is determined by the output value. Specifically, when the output value indicating that the membrane fouling is not deposited to the extent that the separation membrane 123 needs to be cleaned is calculated, it is selected not to perform the cleaning step. In other cases, when an output value indicating that the component to be removed in the membrane fouling is a biofilm is calculated, the alkali cleaning method is selected, and an output value indicating that the component is a scale is calculated. Sometimes an acid cleaning method is selected.

  In the cleaning step, cleaning is performed by the cleaning method selected in the cleaning method designation step. In the cleaning step of the present embodiment, the separation membrane 123 for fouling evaluation is cleaned in addition to the cleaning of the separation membrane in the separation membrane module 101. Therefore, even after cleaning, the membrane fouling of the separation membrane module by the submodule 102 is performed. Reproducibility is maintained.

  In the cleaning step in the present embodiment, the cleaning is performed by the alkali cleaning method or the acid cleaning method by adding the chemical to the supply fluid F upstream of the pressurizing pump 106.

  In this embodiment, when the film fouling deposited on the fouling evaluation separation membrane 123 is a predetermined amount or more, the image acquisition step, the component evaluation step, the cleaning method designation step, and the cleaning step are repeated. Further, if the film fouling does not become less than a predetermined amount even after repeated cleaning, the submodule 102 is replaced.

  Hereinafter, a first specific example of the cleaning method of the membrane separation apparatus will be described with reference to the flowchart of FIG. Note that the membrane separation apparatus in the first specific example has the same configuration as the membrane separation apparatus 110 shown in FIG.

  Step S11 is a starting point of the flowchart. Step S <b> 12 represents the start time of supply of the supply fluid F to the separation membrane module 101 and supply of the sampling fluid S to the submodule 102. That is, step S12 represents the start point of membrane separation by both the separation membrane module 101 and the submodule 102. In the first specific example, an elapsed period t in which the start time is t = 0 is measured.

  Next, in step S13, membrane separation by both the separation membrane module 101 and the submodule 102 is continued over a period of 0 <t <t1 (t1 is 2 to 3 months, for example). Step S13 constitutes a membrane separation step in the first specific example.

  Next, in step S14, the valve 105 is closed, and the supply of the sampling fluid S to the submodule 102 is stopped, whereby the membrane separation by the submodule 102 is stopped. Next, the number of times ct of cleaning (step S23 or step S24 described later) performed after the membrane separation by the submodule 102 is stopped until the membrane separation by the submodule 102 is restarted (step S22 described later) is counted. In step S15, the number of times ct = 0 is set.

  Next, in step S16, a laser beam reflection image is acquired. Next, in step S17, a stain is supplied to the submodule 102, and the stain is brought into contact with the membrane fouling deposited on the separation membrane 123 for fouling evaluation. Next, in step S18, a stained image representing a biofilm is acquired. Steps S16 to S18 constitute an image acquisition step in the first specific example.

  Next, in step S19, information W representing the total volume of membrane fouling and information C representing the volume of the biofilm in the membrane fouling are acquired by analyzing the laser light reflection image and the stained image, and information W And information CR estimated to represent the volume of the scale from the information C. In this specific example, the information W, the information C, and the information CR are numerical information representing the volume. Therefore, in the following of this specific example, the information W is the volume W, the information C is the volume C, and the information CR is the volume CR. Describe each. Step S19 constitutes a component evaluation step in the first specific example.

  Next, in step S20, the magnitude relationship between the volume W and the threshold value W1 is determined. If the relationship of W ≧ W1 is established (“YES” in step S20), the process proceeds to step S21. If the relationship of W ≧ W1 is not established (“NO” in step S20), the valve 105 is opened and the supply of the sampling fluid S to the submodule 102 is resumed, whereby the membrane separation by the submodule 102 is resumed and elapsed. The period t is reset to 0 (step S22), and the process returns to step S13. In step S21, the magnitude relationship between the volume C and the volume CR is determined. If the relationship of C ≧ CR is established (“YES” in step S21), the process proceeds to step S23. If the relationship of C ≧ CR is not established (“NO” in step S21), the process proceeds to step S24. Steps S20 and S21 constitute a cleaning method designating step in the first specific example.

  In step S23, the separation membrane in the separation membrane module 101 and the separation membrane 123 for fouling evaluation are washed by an alkali washing method, and the process proceeds to step S25. In step S24, the separation membrane in the separation membrane module 101 and the separation membrane 123 for fouling evaluation are washed by an acid washing method, and the process proceeds to step S25. Steps S23 and S24 constitute a cleaning step in the first specific example. The cleaning performed in step S23 or step S24 is counted as one cleaning, and 1 is added to the number of times ct to update the number of times ct (step S25).

  Next, in step S26, the magnitude relationship between the number of times ct and the threshold value ct1 is determined. If the relationship of ct ≧ ct1 is established (“YES” in step S26), the process proceeds to step S27. If the relationship of ct ≧ ct1 is not established (“NO” in step S26), the process returns to step S16. Although ct1 depends on the type of separation membrane and the supply fluid F, it is about 15 to 20, for example.

  In step S27, it is notified that the submodule 102 should be replaced (for example, the lamp is turned on), and the process proceeds to step S28. Step S28 is the end point of the flowchart.

  In this specific example, the separation membrane in the separation membrane module 101 can be cleaned by an appropriate cleaning method. Further, when the deposition amount of the membrane fouling on the fouling evaluation separation membrane 123 is a predetermined amount or more, the cleaning is repeatedly performed. Further, if the membrane fouling does not become less than a predetermined amount even after repeated cleaning, it can be grasped that the submodule 102 should be replaced.

  The cleaning method of the membrane separator is not limited to the cleaning method of the first specific example. Hereinafter, a second specific example of the cleaning method of the membrane separation apparatus will be described with reference to the flowchart of FIG. In the flowchart of FIG. 7, the same steps as those in the flowchart of FIG. 6 are denoted by the same reference numerals, and the description thereof is omitted. Further, in the membrane separation apparatus in the second specific example, instead of the stain tank 104 in the first specific example, the first tank in which the first stain for specifically detecting viable bacteria and the dead bacteria are stored. A second tank in which a second stain for specific detection is stored is installed. Further, a first valve connected to the first tank and a second valve connected to the second tank are installed instead of the valve 107 in the first specific example. In other respects, the membrane separator in the second specific example is the same as the membrane separator in the first specific example.

  In the second specific example, after the laser light reflection image is acquired in step S16, the process proceeds to step S117. In step S117, the first valve and the second valve are opened, the first stain and the second stain are supplied to the submodule 102, and the first stain and the fouling deposited on the separation membrane 123 for fouling evaluation are added. A second stain is contacted. Next, in step S118, a first stained image representing a biofilm derived from live bacteria and a second stained image representing a biofilm derived from dead bacteria are acquired. Step S16, step S117, and step S118 constitute an image acquisition step in the second specific example.

  Next, in step S119, from the laser light reflection image, the first stained image, and the second stained image, information W1 indicating the total volume of the membrane fouling, information c1 indicating the volume of the biofilm derived from viable bacteria in the membrane fouling. And information c2 representing the volume of the dead germ-derived biofilm in membrane fouling is obtained, and information CR estimated to represent the volume of the scale is obtained from information W, information c1, and information c2. In the following of this specific example, information W is described as volume W, information c1 as volume c1, information c2 as volume c2, and information CR as volume CR. Step S119 constitutes a component evaluation step in the second specific example.

  In the second specific example, the magnitude relationship between the volume W and the threshold value W1 is determined in step S20, and if the relationship of W ≧ W1 is established (“YES” in step S20), the process proceeds to step S121. In step S121, the magnitude relationship between the sum of the volumes c1 and c2 and the volume CR is determined. If the relationship of c1 + c2 ≧ CR is established (“YES” in step S121), the process proceeds to step S221. If the relationship of c1 + c2 ≧ CR is not established (“NO” in step S121), the process proceeds to step S24. In step S221, the magnitude relationship between the volume c1 and the volume c2 is determined. If the relationship of c1 ≧ c2 is established (“YES” in step S221), the process proceeds to step S123. If the relationship of c1 ≧ c2 is not satisfied (“NO” in step S221), the process proceeds to step S223. Step S20, step S121, and step S221 constitute a cleaning method designation step in the second specific example.

  In step S123, the separation membrane in the separation membrane module 101 and the separation membrane 123 for fouling evaluation are washed by a sterilization washing method, and the process proceeds to step S25. In step S223, the separation membrane in the separation membrane module 101 and the separation membrane 123 for fouling evaluation are washed by the flushing washing method, and the process proceeds to step S25. Step S24, step S123, and step S223 constitute a cleaning step in the second specific example. The cleaning performed in step S24, step S123 or step S223 is counted as one cleaning, and 1 is added to the number of times ct to update the number of times ct (step S25).

  In the second specific example, the biofilm volume in membrane fouling is obtained by dividing the biofilm-derived biofilm volume c1 and the dead-bacterium-derived biofilm volume c2, and the sum of the volume c1 and the volume c2 is the volume. By comparing the size relationship between volume c1 and volume c2 in the case of CR or more, washing suitable for removing biofilm derived from live bacteria and washing suitable for removing biofilm derived from dead bacteria are selectively performed. To do. Therefore, the biofilm can be removed more effectively than in the first specific example.

  The cleaning method based on the flowcharts of FIGS. 6 and 7 is implemented using, for example, a microcomputer having a built-in program. Specifically, if a microcomputer is used, the timing of proceeding to each step, the opening / closing mechanism of each valve, and the like can be controlled.

Example 1
In Example 1, a supply fluid obtained by pretreating groundwater with an MF membrane was supplied to the separation membrane (RO membrane), so that membrane fouling was deposited on the separation membrane, and sample A was obtained.

  Next, the membrane fouling in Sample A was stained with a viable and dead bacteria staining reagent (manufactured by Invitrogen), which is a mixed solution of SYTO9 that binds to live bacteria and PI that binds to dead bacteria, and air-dried. Next, the laser light reflection image and the staining image of the film fouling in sample A were obtained as a three-dimensional image by a confocal laser microscope (LSM510 META, manufactured by Carl Zeiss). Specifically, a laser beam reflection image was obtained by setting the wavelength of the laser beam to 488 nm and using a 420 nm long pass filter. In addition, as a stained image, a stained image derived from SYTO 9 and a stained image derived from PI were individually acquired, and each stained image was synthesized into one stained image by an image analysis device built in the confocal laser microscope. When acquiring a stained image derived from SYTO9, sample A was irradiated with excitation light of 488 nm, and an image based on green fluorescence emitted from SYTO9 was acquired using a 505-530 nm bandpass filter. When obtaining a stained image derived from PI, sample A was irradiated with excitation light of 543 nm, and an image based on red fluorescence emitted from PI was obtained using a 560 nm long-pass filter. FIG. 8A shows a perspective view of the acquired stained image, and FIG. 8B shows a perspective view of the laser light reflected image acquired.

  The stained image shown in FIG. 8A indicates that only red fluorescence indicating dead bacteria is distributed in a limited region of the observation region. On the other hand, the laser beam reflected image shown in FIG. 8B is distributed over a wide observation area. By visually comparing the stained image shown in FIG. 8A and the laser light reflected image shown in FIG. 8B, it can be understood that most of the film fouling in the sample A is a scale (inorganic substance).

In addition to visual comparison, the membrane fouling components were quantified by image analysis. Specifically, the image analysis software built in the confocal laser microscope analyzes the laser light reflection image and the stained image, and the volume per unit area of the film surface of the film fouling represented by the laser light reflection image ( μm ³ / μm ² ) and the volume per unit area of the membrane fouling represented by the stained image. The volume per unit area of the film fouling represented by the laser light reflection image was 11.3 μm ³ / μm ² . The volume per unit area of the membrane fouling represented by the stained image was 0.8 μm ³ / μm ² . Based on the comparison result between the laser light reflection image and the stained image, alkali cleaning was selected as the cleaning of sample A.

Sample A was washed with alkali for 1 hour. The alkali cleaning was performed with an aqueous NaOH solution (pH 12). The volume per unit area of the film fouling represented by the laser light reflection image after washing is 5.5 μm ³ / μm ² , and the volume per unit area of the film fouling represented by the stained image is 0.4 μm ³ / μm ^2. Met. Table 1 summarizes the change in volume per unit area of the film fouling represented by the laser light reflection image and the volume per unit area of the film fouling represented by the dyed image.

  As shown in Table 1, both the volume per unit area of the film fouling represented by the laser light reflection image and the volume per unit area of the film fouling represented by the dyed image were reduced to less than half by the alkali cleaning. Therefore, it can be said that it was appropriate to select alkaline cleaning as cleaning.

(Example 2)
In Example 2, membrane fouling is deposited on a separation membrane by supplying a supply fluid obtained by subjecting domestic wastewater to activated sludge treatment and further pretreating with an MF membrane to the separation membrane (RO membrane). Sample B was obtained.

  Also in Example 2, a laser light reflection image and a dyed image of film fouling in Sample B were obtained in the same procedure as Example 1. The stained image acquired in FIG. 9A and the laser beam reflection image acquired in FIG. 9B are shown. 9A and 9B, the upper side is a perspective view, and the lower side is a cross-sectional view in which the vertical axis is the thickness direction. According to the cross-sectional view, it is possible to easily grasp the thickness, which is one of the effective indexes for evaluating the film fouling, by visual observation. Being able to grasp the thickness is convenient for evaluating the effect of cleaning the sample.

  By comparing the stained image shown in FIG. 9A with the laser light reflected image shown in FIG. 9B by visual observation, most of the region where the laser light reflected image shown in FIG. It turns out that it overlaps with the distributed area. Thereby, it is grasped that the main component of membrane fouling in sample B is a biofilm.

  Further, in the stained images shown in FIGS. 9A and 9B, both green fluorescence indicating viable bacteria and red fluorescence indicating dead bacteria exist (hatching in FIGS. 9A and 9B indicates that green fluorescence is present). Where it exists). As the cleaning of the sample B, alkaline cleaning may be selected. In addition, based on the comparison result between the green fluorescence and the red fluorescence, the washing of the sample B may be selected from washing that can remove live bacteria and washing that can remove dead bacteria.

  Information obtained in the present invention is useful for evaluating membrane fouling.

8,108 Confocal optical microscope 23 Separation membrane 23f Main surface 81 Image analysis device 82 Light receiving element 83 Pinhole panel 84 Imaging lens 85 Half mirror 86 Objective lens 87 Light source 90 Membrane fouling 101 Separation membrane module 102 Submodule 104 Staining agent Tank 105, 107 Valve 106 Pressure pump 110 Membrane separation device 111 First flow path 112 Second flow path 122 Deposited material 123 Fouling evaluation separation film 123f Membrane surface 123b Membrane back surface 124 Permeation side flow path material 127 Inflow port 128 Concentrated fluid outflow port 129 Permeated fluid outflow port 130 Container 131 Container body 132 Lid 141 Female screw 142 Male screw 150 Opening 161 Supply side channel 162 Permeation side channel

Claims (13)

A method for evaluating membrane fouling deposited on the main surface of a separation membrane that separates a supply fluid to generate a permeated fluid,
The membrane fouling deposited on the main surface of the separation membrane for fouling evaluation for membrane separation of the separation fluid flowing from the separation membrane or the supply fluid is evaluated, and the laser light reflection image of the membrane fouling, An image acquisition step of acquiring a stained image of membrane fouling;
Component evaluation for acquiring information W regarding the total amount of the film fouling from the laser light reflection image and acquiring information C regarding the amount of some of the plurality of components constituting the film fouling from the stained image A method for evaluating membrane fouling.   2. The film fouling evaluation method according to claim 1, wherein in the component evaluation step, the information W and the information C are acquired by performing image analysis on the laser light reflected image and the stained image, respectively.   The film fouling evaluation method according to claim 2, wherein the information W and the information C are digitized information.   4. The information CR regarding the amount of the remaining component excluding the amount of the partial component of the plurality of components is acquired from the information W and the information C in the component evaluation step. The method for evaluating membrane fouling according to one item.   5. The film fouling evaluation method according to claim 1, wherein the information C includes information c <b> 1 related to the amount of the first component and information c <b> 2 related to the amount of the second component.   The film fouling according to any one of claims 1 to 5, wherein, in the image acquisition step, the stained image is acquired after bringing a staining agent that stains the part of the component into contact with the film fouling. Evaluation method.   The film fouling evaluation method according to claim 6, wherein, in the image acquisition step, the stain is brought into contact with the film fouling after the laser light reflection image is acquired.   The film fouling evaluation method according to any one of claims 1 to 7, wherein in the image acquisition step, the laser light reflection image and the stained image are acquired by a confocal optical microscope. The evaluation object is a membrane fouling deposited on the main surface of the separation membrane for fouling evaluation that separates the sampling fluid that flows from the supply fluid.
The membrane fouling evaluation method according to any one of claims 1 to 8, wherein the separation membrane for fouling evaluation is made of the same material as that of the separation membrane. A membrane fouling evaluation step for implementing the method for evaluating membrane fouling according to any one of claims 1 to 9,
A cleaning method designating step of designating a cleaning method determined by the information W and the information C;
A cleaning step of cleaning the separation membrane by the cleaning method. In the component evaluation step, information CR regarding the amount of the remaining component excluding the amount of the partial component of the plurality of components is acquired from the information W and the information C,
The separation membrane cleaning method according to claim 10, wherein a cleaning method determined by the information C and the information CR is specified in the cleaning method designating step.   The cleaning method according to claim 10 or 11, wherein, in the cleaning method designating step, the cleaning method is selected and designated from an acid cleaning method and an alkali cleaning method.   The cleaning method according to claim 10 or 11, wherein, in the cleaning method designation step, the cleaning method is selected and designated from an acid cleaning method, a sterilization cleaning method, and a flushing cleaning method.