JP5114831B2 - Method for diagnosing contamination state of membrane separator and cleaning method for membrane separator - Google Patents

Description

  The present invention relates to a diagnostic method for diagnosing a contamination state of a membrane provided in a membrane separation device, a diagnostic device, and a cleaning method for the membrane separation device, and more particularly, a membrane separation including a separation membrane for water treatment such as a reverse osmosis membrane. The present invention relates to a diagnostic method, a diagnostic device, and a cleaning method for a contamination state of an apparatus.

  2. Description of the Related Art Conventionally, a water separation plant or the like that manufactures washing water for semiconductor products, pharmaceutical production water, and the like has been provided with a membrane separation device that includes a separation membrane such as a reverse osmosis membrane, an ultrafiltration membrane, or a microfiltration membrane. When the operation of such a membrane separation apparatus is continued, various contaminants adhere to the surface of the separation membrane. Contaminants are roughly divided into inorganic substances and organic substances. Examples of inorganic substances include calcium carbonate scales due to calcium contained in the liquid to be treated.Examples of organic substances include turbid substances, surfactants, and Examples include bacteria grown on a membrane separation device.

  Conventionally, the membrane separator has been regularly cleaned against such contamination of the separation membrane. However, periodic cleaning does not necessarily perform cleaning according to the contamination state of the separation membrane, and may cause problems such as degradation of the separation membrane and reduction in operating efficiency of the membrane separation apparatus. For this reason, in Patent Document 1, the pressure of the liquid to be treated to be supplied to the membrane separation device, the osmotic pressure of the surface of the separation liquid to be treated (the first membrane surface) attached to the membrane separation device, and the separation membrane Based on the flow rate of the permeated liquid that permeates, a method for diagnosing membrane contamination and optimizing the cleaning time of the separation membrane has been proposed.

On the other hand, as a method for identifying contaminants adhering to the separation membrane, a method of observing the membrane surface using a scanning electron microscope (SEM), or an inorganic component adhering to the membrane surface using a fluorescent X-ray analyzer is used. There are a method for performing analysis, a method for performing analysis of organic substances using an infrared absorption spectrometer (IR), and the like.
Japanese Patent No. 3311158

  By the way, since the pollutant is not specified in the method described in Patent Document 1, the cleaning chemical and the cleaning method used for cleaning the membrane separation apparatus may not necessarily be suitable for the property of the pollutant.

  In addition, since contamination of the membrane surface is often caused by a combination of inorganic contamination and organic contamination, simply identifying the contamination of the membrane using an analyzer such as an IR will change the contamination state of the separation membrane. In some cases, sufficient information cannot be obtained for accurate understanding. For example, when it is found by analysis using a fluorescent X-ray analyzer that the calcium carbonate scale is contained in the pollutant, conventionally, the scale is cleaned with an acid having a high cleaning effect. However, the effect of acid cleaning may be low.

  Furthermore, observation of the film surface by SEM and analysis of organic substances by IR can identify specific pollutants such as turbidity and microorganisms, but identify other organic and inorganic substances, and identify the causative substances of complex pollution. It was difficult to comprehensively judge the contamination status. Furthermore, analysis using an analyzer such as SEM or IR is complicated in operation, requiring skill to perform an accurate analysis, and in order to identify pollutants in consideration of the water quality of the liquid to be treated. There is also a problem of requiring knowledge and experience.

  In view of the above problems, the present invention uses a diagnosis method for a membrane separation apparatus that can easily diagnose the contamination state of a separation membrane with high accuracy even with a separation membrane to which various types of contaminants adhere, and uses this diagnosis method. It is an object of the present invention to provide a cleaning method for a conventional membrane separator.

  The inventors of the present invention have found that the change pattern of the surface shape of the separation membrane differs depending on the type of contaminant adhering to the separation membrane, and have completed the present invention. Specifically, the inventors have changed the surface roughness of the surface of the separation membrane to be treated (the first membrane surface) and either organic contaminants or inorganic contaminants adhering to the separation membrane. The inventors have found that by using one or both of the adhesion amounts as an index, it is possible to grasp the contamination state of the separation membrane in a pattern, and the present invention has been completed. More specifically, the present invention provides the following.

(1) a first film surface facing a liquid to be treated containing impurities, a second film surface opposite to the first film surface and facing a permeated liquid from which impurities have been removed from the liquid to be treated; A method for diagnosing a contamination state of a membrane separation apparatus comprising a separation membrane having
A measurement step of measuring a change in surface roughness of the first film surface and an inorganic material adhesion amount attached to the first film surface to obtain respective measurement values; and after the measurement step, the first film A two-dimensional plotting step for creating a two-dimensional plot diagram by plotting the measurement values obtained in the measurement step on a plan view with the change in surface roughness of the surface and the amount of inorganic matter attached as coordinate axes, Based on the measured values shown in the two-dimensional plot, the change value of the surface roughness is lower than a first predetermined reference value, and the value of the inorganic substance adhesion amount is a second predetermined reference value. If lower, the contamination principal substances diagnosed with organics, the one value of the change of surface roughness is lower than the first predetermined reference value, the value of the inorganic deposition amount is the second predetermined reference higher than the value, seen as the type of pollution organic and the inorganic substances bound And, further, the value of the change of the surface roughness is first higher than a predetermined reference value, and, when the value of the inorganic adhesion amount is higher than the second predetermined reference value, mainly contaminants Is a method for diagnosing the contamination state of a membrane separation apparatus, comprising a diagnostic step for diagnosing inorganic substances.

  The present invention can be applied to any membrane separation device such as a microfiltration membrane device as a separation membrane, an ultrafiltration membrane device including an ultrafiltration membrane, and a reverse osmosis membrane device including a reverse osmosis membrane. The membrane module format of the membrane separator is not particularly limited, and can be applied to any format such as a flat membrane type, a tubular type, a spiral type, and a hollow fiber type.

  The membrane separation device supplies a liquid to be processed containing impurities to the first film surface side, and selectively transmits the liquid to the second film surface side to obtain a permeated liquid from which impurities have been removed from the liquid to be processed. In addition, contaminants such as impurities contained in the liquid to be processed adhere to the surface of the first film surface in contact with the liquid to be processed. The surface roughness of the first membrane surface changes due to the adhesion of such contaminants, and in the present invention, the change in the surface roughness of the first membrane surface due to the adhesion of contaminants is one of the indicators for diagnosing the contamination state of the separation membrane. .

In the present invention, even if the separation membrane is complexly contaminated with a plurality of contaminants from the relationship between the change in surface roughness of the first membrane surface and the amount of inorganic matter deposited on the first membrane surface. The contamination type can be diagnosed by simply and reliably grasping the contamination type.

  The change in surface roughness is determined from the measurement values obtained by measurement using a laser microscope, atomic force microscope, friction force microscope, scanning tunneling microscope (STM), SEM, transmission electron microscope, etc. It can be quantified as a roughness shape parameter (JIS standard number B0601: 2001) according to the JIS standard. The change in surface roughness may be quantified using parameters other than JIS standards such as root mean square roughness (RMS), average unevenness height (Rc), or peak count (Pc). Furthermore, the surface roughness changes as the ratio of the surface area of the unused separation membrane (hereinafter referred to as “new membrane”) to which the contaminants are not attached to the surface area of the separation membrane to which the contaminants to be diagnosed are attached. It can also be digitized.

  Arbitrary parameters can be used as parameters of the JIS standard representing changes in surface roughness. For example, values such as arithmetic average height (Ra) or maximum height (Rz) can be used. For example, the arithmetic average height (Ra) is obtained according to the following equation. In the formula, “f (x)” means the height of the roughness curve on the reference line when the average line of the roughness curve is the reference line, and “l” is the length of the reference line to be measured. is there.

In the present invention, the amount of contaminants attached to the first film surface is also measured to obtain a measured value. As the pollutant, an inorganic substance may be measured.

  As for the amount of inorganic substances attached, for example, a fluorescent X-ray analyzer, an atomic spectrum analyzer, a plasma emission analyzer (ICP), etc. can be used alone or in combination, and the amount of each inorganic substance attached can be determined. The adhesion amount of the organic substance can be determined by using any measuring device such as IR, mass spectrometer (GC-MAS), and nuclear magnetic resonance apparatus (NMR) alone or in combination. For example, IR may be used to determine the amount of contaminants left attached to the separation membrane, and the deposits may be dissolved from the separation membrane using an alkaline solution or an organic solvent, and an ultraviolet ray measuring device or the like may be used. Then, the amount of organic matter (TOC) in the solution may be measured. Note that a surfactant, which is a kind of organic substance, generally has a low concentration in the liquid to be treated, but it affects the contamination state of the film, so it may be measured separately from other organic substances.

The measurement process is performed by the above-described method. In the invention described in (1) , the measurement process is performed on the two-dimensional coordinates in which the surface roughness of the first film surface is changed and the amount of inorganic substances attached is X and Y axes. Plot the measured values obtained in step 1. The two-dimensional plot diagram in which the measurement values are plotted is used for diagnosing the contamination state of the separation membrane based on the dispersion pattern of the points representing the measurement values described in the drawing. According to the present invention, the contamination state of the separation membrane can be diagnosed simply by determining the amount of inorganic matter attached.

In the following, the two-dimensional plot diagram created by using the total amount of adhesion, which is the total amount of contaminants adhering to the first film surface, as an index instead of the amount of either inorganic or organic substances , the invention according to (1) In order to distinguish from the two-dimensional plot created by the above, the former may be particularly referred to as an “adhesion total amount plot”.

(2) In the diagnostic step, based on the measurement value shown in the two-dimensional plot diagram, the value of the change in surface roughness is lower than the first predetermined reference value in the two-dimensional plot diagram, And the area | region where the value of the said inorganic substance adhesion amount is lower than the said 2nd predetermined reference value is made into the 1st area | region, and while the value of the said surface roughness change is lower than the said 1st predetermined reference value, the said inorganic substance A region having an adhesion amount value higher than the second predetermined reference value is defined as a second region, and further, the surface roughness change value is higher than the first predetermined reference value, and the inorganic substance adhesion The method for diagnosing a contamination state of a membrane separation apparatus according to (1), comprising classifying a region having a quantity value higher than the second predetermined reference value as a third region.
(3) In the measurement step, a change in surface roughness of the first film surface, an inorganic material adhesion amount adhering to the first film surface, and an organic material adhesion amount adhering to the first film surface are measured. give each measurement value each, after the measurement step, a change in the surface roughness, and the inorganic adhesion amount, by plotting the measured values and the organic material deposition amount, the three-dimensional view of the coordinate axes dimensional plot step of creating a three-dimensional plot provided, in addition to the diagnostic process, film according to further comprising (1) a diagnostic step of diagnosing the contamination state of the separation membrane by using the three-dimensional plot A method for diagnosing the contamination status of a separator.

In the invention described in (3) , the measurement values obtained by the above-described measurement method are plotted on a three-dimensional drawing in which the change in surface roughness of the first film surface, the organic matter adhesion amount, and the inorganic matter adhesion amount are coordinate axes. . According to the present invention, the contamination state of the separation membrane can be diagnosed more accurately and comprehensively.

(4) In the diagnostic step based on the two-dimensional plot diagram, based on the measured value shown in the two-dimensional plot diagram, the value of the change in the surface roughness of the two-dimensional plot diagram is the first predetermined value. A region where the value of the inorganic substance adhesion amount is lower than the second predetermined reference value is defined as a first region, and the change value of the surface roughness is the first predetermined reference value. while lower, the value of the inorganic deposition amount is the second predetermined higher than the reference value region as a second region, further, the value of the change in the surface roughness is higher than the first predetermined reference value The method for diagnosing a contamination state of a membrane separation apparatus according to (3) , further comprising classifying a region having a value of the inorganic substance adhesion amount higher than the second predetermined reference value as a third region.
(5) In the diagnosis step, when the organic substance adhesion amount serving as a coordinate axis of the three-dimensional plot diagram is a nonionic surfactant adhesion amount, the measured value shown in the two-dimensional plot diagram is the third region. Further, when the measured value of the organic substance adhesion amount shown in the three-dimensional plot diagram is lower than a third predetermined reference value , the contamination state of the membrane separation device is an inorganic-based contamination type. The method for diagnosing a contamination state of a membrane separation apparatus according to (4) , wherein a diagnosis is made that there is mild contamination with a nonionic surfactant.
(6) In the diagnosis step, when the organic substance adhesion amount serving as the coordinate axis of the three-dimensional plot diagram is a nonionic surfactant adhesion amount, the measured value shown in the two-dimensional plot diagram is the first region. Furthermore, when the measured value of the nonionic surfactant adhesion amount shown in the three-dimensional plot is 0, the contamination state of the membrane separation device is an organic matter-based contamination type, The diagnosis method for the contamination state of the membrane separation apparatus according to (4) , wherein the diagnosis is substantially free from contamination by an ionic surfactant.
(7) In the diagnostic step, when the organic substance adhesion amount serving as the coordinate axis of the three-dimensional plot diagram is a nonionic surfactant adhesion amount, the measured value shown in the two-dimensional plot diagram is the second region. In addition, when the measured value of the nonionic surfactant adhesion amount shown in the three-dimensional plot diagram is lower than the third predetermined reference value , the contamination state of the membrane separation device is determined as an organic substance and an inorganic substance. (4) The diagnosis method of the contamination state of the membrane separation apparatus according to (4) , wherein the contamination type is a combined contamination type in which
(8) In the diagnosis step, when the organic substance adhesion amount serving as the coordinate axis of the three-dimensional plot diagram is a nonionic surfactant adhesion amount, the measured value shown in the two-dimensional plot diagram is the second region. Furthermore, when the measured value of the nonionic surfactant adhesion amount shown in the three-dimensional plot diagram is 0, the contamination state of the membrane separation device is a combined type in which an organic substance and an inorganic substance are combined. The method for diagnosing a contamination state of a membrane separation apparatus according to (4) , wherein the contamination type is diagnosed as being substantially free from contamination by a nonionic surfactant.
(9) In the diagnosis step, when the organic substance adhesion amount serving as the coordinate axis of the three-dimensional plot diagram is a nonionic surfactant adhesion amount, the measured value shown in the two-dimensional plot diagram is the first region. Further, when the measured value of the nonionic surfactant adhesion amount shown in the three-dimensional plot diagram is higher than the third predetermined reference value , the contamination state of the membrane separation device is determined as an organic matter-based type. The method for diagnosing the state of contamination of the membrane separation apparatus according to (4) , wherein the contamination type is diagnosed as having severe contamination by a nonionic surfactant.
(10) The method for diagnosing a contamination state of a membrane separation apparatus according to any one of (1) to (9) , wherein the separation membrane is a reverse osmosis membrane.

  Although the present invention is originally applicable regardless of the membrane material of the separation membrane, the reverse osmosis membrane that separates even ions in the liquid to be treated is likely to be complexly contaminated by various contaminants. Applicable.

(11) The method for diagnosing a contamination state of a membrane separation device according to (10) , wherein the reverse osmosis membrane includes a skin layer made of polyamide.

  As the membrane material of the reverse osmosis membrane, cellulose acetate, polyamide, polyvinyl alcohol, polyvinylidene fluoride and the like are used, and the present invention can be applied to separation membranes of these arbitrary materials. Among these membrane materials, especially aromatic polyamide-based separation membranes before cross-linking have a strong correlation between changes in membrane surface roughness and the amount of contaminants attached, and changes in membrane surface roughness are clear. The present invention can be suitably applied.

(12) The reverse osmosis membrane is a composite membrane comprising the skin layer and a support layer that is composed of a porous body and supports the skin layer, wherein the skin layer is on the first membrane surface side, The method for diagnosing a contamination state of a membrane separation device according to (11) , wherein the support layer is located on the second membrane surface side.

  An asymmetric membrane in which a skin layer having a selective permeation function such as desalting is formed on one surface of a porous support layer is a skin layer having a desalting function as a first membrane surface in contact with the liquid to be treated. The support layer that supports the skin layer is attached to the membrane module as the second membrane surface. Such an asymmetric composite membrane can add various functions by changing the material of the skin layer portion as compared with a separation membrane composed of a single material. Since an extremely thin layer can be obtained, there is an advantage that the transmission speed can be increased.

  The present invention can diagnose the contamination state from the change in the surface roughness of the skin layer serving as the first film surface and the amount of the contaminant adhering to the skin layer, and is therefore suitable for a composite film having an extremely thin skin layer. Can be used for In recent years, membranes that increase the surface area and increase the amount of permeate by using a “folded structure” by three-dimensionally growing a skin layer have been used. Since the contamination state can be diagnosed from the change in the surface roughness of the skin layer, the present invention can be particularly suitably used for a film having such a pleated structure.

(13) A diagnostic process for diagnosing a contamination state of a separation membrane having a first membrane surface facing a liquid to be treated containing impurities and a second membrane surface opposite to the first membrane surface, and this diagnosis And a cleaning step for cleaning the separation membrane based on a result of the step, wherein the membrane separation device according to any one of (1) to (12) in the diagnosis step Cleaning method for a membrane separation device for diagnosing the contamination state of a separation membrane by a method for diagnosing the contamination state of

The function of the separation membrane diagnosed by the diagnostic methods (1) to (12) can be restored by washing it with an appropriate washing method employed according to the contaminated state. Such a diagnostic process and a cleaning process performed subsequent to this diagnostic process can be incorporated into the operation management process of the membrane separation apparatus. In the present invention, since an appropriate cleaning chemical and cleaning method can be selected by diagnosing the contamination state of the separation membrane, the cleaning effect is enhanced and the amount of chemical used for cleaning the separation membrane can be reduced.

In the inventions described in (1) to (13) above, an instrument such as SEM for measuring the roughness of the separation membrane surface is used as a surface roughness measuring means, and an analyzer such as IR, GC-MAS, or ICP is used to measure the deposits. Further, it can be implemented by an apparatus provided with arithmetic means such as a central processing unit (CPU), and information processing means such as a computer for determining a contamination state from the surface roughness and the amount of deposits as diagnostic means. The surface roughness measuring means, the adhering matter measuring means, and the diagnostic means may be provided at separate locations, or both means may be arranged adjacent to the membrane separation device.

  According to the present invention, the contamination state of the separation membrane can be diagnosed easily and with high accuracy. In particular, in the present invention, even when the separation membrane is complexly contaminated with two or more contaminants, it is possible to appropriately diagnose the contamination type and select an optimal cleaning method.

  Next, the present invention will be described in detail with reference to the drawings. FIG. 1 is an exploded schematic view of a spiral membrane module 1 constituting a membrane separation apparatus. The membrane module 1 includes a membrane body 10 composed of a reverse osmosis membrane as a separation membrane, a net-like spacer 20 disposed on one surface of the membrane body 10, and a collecting tube for collecting permeate from which impurities are removed. 30. One end edge of the membrane body 10 and the spacer 20 is connected to the liquid collection tube 30, and the membrane module 1 has a substantially cylindrical shape by winding the membrane body 10 and the spacer 20 around the liquid collection tube 30.

  For example, the membrane separation apparatus is configured such that the membrane module 1 is housed inside a substantially cylindrical container (not shown). In such a membrane separator, the liquid to be treated is introduced into a substantially cylindrical container, and the permeate that has permeated through the reverse osmosis membrane 11 is taken out from the liquid collection tube 30, so that deionized water or the like from which impurities have been removed is removed. A permeate is obtained.

  FIG. 2 is a schematic view in which a part of the film body 10 is cut out along the broken line shown in FIG. The membrane body 10 is composed of a substantially bag-like reverse osmosis membrane 11 whose peripheral edge is closed with an adhesive or the like except for an edge connected to the liquid collection tube 30, and promotes the flow of the permeated liquid inside the membrane body 10. For this purpose, a net-like permeate spacer 40 is arranged.

  FIG. 3 is an enlarged schematic view of the cross section of the reverse osmosis membrane 11 in the portion indicated by A in FIG. In this embodiment, the reverse osmosis membrane 11 has a skin layer 12 made of, for example, a pre-crosslinked aromatic polyamide and a support layer 13 made of polysulfone that supports the skin layer 12 as shown in FIG. As shown in FIG. 2, it is a composite membrane, and has a bag shape with the skin layer 12 on the outside and the support layer 13 on the inside.

  The liquid to be treated is supplied to the outside of the bag-like membrane body 10, and the permeate that has permeated through the reverse osmosis membrane 11 is collected from the bag-like membrane body 10 into the liquid collecting tube 30. In the membrane module 1, the first membrane surface 12 s in contact with the liquid to be treated is a surface constituted by the skin layer 12 of the reverse osmosis membrane 11, and the second membrane surface 13 s in contact with the permeate is constituted by the support layer 13. It is a surface.

  In a membrane separation apparatus having such a membrane module, as the operating time elapses, impurities and the like contained in the liquid to be treated adhere to the surface of the first membrane surface in contact with the liquid to be treated. As described below, the inventors of the present invention have found that the state of adhesion of contaminants adhering to the first film surface differs depending on the type of contaminant.

  FIG. 4 is a schematic view showing a state where an organic substance such as a surfactant or protein, or aluminum hydroxide P is attached as a contaminant on the surface of the skin layer 12 of the reverse osmosis membrane 11, that is, the first membrane surface 12 s. It is. As shown in FIG. 4, since the organic substance or aluminum hydroxide P is thinly adsorbed on the entire first film surface 12s, the film surface shape is hardly changed, and the change in the surface roughness of the first film surface 12s is small. . Even if it is an inorganic pollutant, aluminum hydroxide hardly changes the film surface shape like the organic substance P.

  On the other hand, when a contaminant mainly composed of an inorganic substance adheres to the first film surface, the change in the film surface shape becomes large. FIG. 5 is a diagram schematically showing a state in which an inorganic scale substance S such as calcium carbonate adheres to the first film surface 12s. As shown in FIG. 5, since the scale material S such as calcium carbonate grows in a direction perpendicular to the surface direction of the first film surface 12s, the first film surface 12s to which the scale material S is attached Unevenness composed of the scale material S is formed, and the surface area is increased.

  In addition, as shown in FIG. 6, when a polyvalent cation C such as calcium ion is bonded to a carboxyl group of a polymer organic substance P such as humic that is an organic substance, the organic substance P is laminated and the unevenness of the first film surface 12s is formed. There is a change in surface roughness that decreases.

  Based on the above findings, the present invention measures the change in the surface shape of the first membrane surface 12s and the amount of organic or inorganic contaminants on the first membrane surface 12s or both, Diagnose contamination status. Hereinafter, one embodiment of the diagnostic method will be described. In this embodiment, separation membranes contaminated with contaminants (hereinafter referred to as “contaminated membranes”) are targeted for diagnosis, and the change in surface area is quantified based on the ratio of the surface area between the contaminated membrane and the new membrane to determine the contamination state of the contaminated membrane. Diagnose.

As a specific method, the contaminated film is first naturally dried at a room temperature of about 25 ° C. Next, as a measurement step, the actual surface area of the first film surface 12s of the unit film area (for example, per 1 μm ^{2 of the} contaminated film) is measured using a laser microscope (for example, an ultra-deep color shape measurement microscope). Since the surface area of the first film surface 12 s varies depending on the site, a plurality of measurement values are obtained by setting the measurement symmetrical sites to about 5 to 20, and the average value of the plurality of measurement values is obtained as the surface area value (V _f ) of the contaminated film. It is preferable that

Similarly, the surface area (V ₀ ) is also obtained for a new membrane that is the same type as the membrane to be diagnosed and has no contaminants attached thereto. The change (V) in the surface shape of the first film surface 12s is based on the surface area V _f (μm ² / μm ² ) of the contaminated film and the surface area V ₀ (μm ² / μm ² ) of the new film obtained by the above method. It is calculated | required by Numerical formula 2 shown below as a surface area ratio.

  The change in the surface shape may be expressed by, for example, the arithmetic average height (Ra) of JIS standard 0601, etc., and the unused reverse osmosis membrane 11 having the skin layer 12 made of the above-mentioned pre-crosslinking aromatic polyamide. In this case, the arithmetic average height Ra of the skin layer 12 is, for example, about 0.3 μm or more.

On the other hand, with respect to the adhesion amount of contaminants, the adhesion amount of the inorganic substance S adhering to the first film surface 12s is measured using, for example, a fluorescent X-ray analyzer. In the measurement by the fluorescent X-ray analysis method, the fluorescence intensity detected varies depending on the sensitivity of each element. Therefore, for example, the amount of adhesion when the inorganic substance S is calcium on the basis of calcium is represented by 1 according to the following mathematical formula 3. In this case, the adhesion amount ratio M of the inorganic substance S may be expressed as a relatively numerical value. In the formula, “Ka” is the conversion factor (/ kcps) of element a, Xa is the fluorescence intensity (kcps) of element a, and similarly, “Kb” is the conversion factor of element b, and Xb is the fluorescence of element b. It means strength.

  In addition, sulfur (S) and chlorine derived from the membrane material of the separation membrane may be excluded from the calculation formula for obtaining the adhesion amount ratio M of the inorganic substance. Similarly, aluminum is an amphoteric metal and is used for acid cleaning and alkali cleaning. Since either can be efficiently cleaned, it may be excluded from Equation 3 for calculating the adhesion amount ratio M of the inorganic substance.

  When calculating only the amount of inorganic matter deposited as a pollutant, for example, write the measured value obtained by the above method on a plane coordinate with the horizontal axis (logarithmic axis) representing the change in surface roughness and the vertical axis representing the amount of inorganic matter deposited. Create a 2D plot. FIG. 7 is a two-dimensional plot diagram in which the surface area ratio V showing the change in surface roughness is a plane coordinate with the horizontal axis (logarithmic axis) and the inorganic substance adhesion amount ratio M as the vertical axis, and the surface area ratio V and the inorganic substance adhesion. When both of the quantity ratios M are low (when plotted in the region Z), as described above, the main contaminant is diagnosed as an organic substance, and the surface area ratio V is low, while the inorganic adhesion quantity ratio M is When it is relatively high (when plotted within the region W), it can be diagnosed as a contamination type in which calcium ions or the like are bound to the carboxyl group of the organic substance. Further, when both the surface area ratio V and the inorganic adhesion amount ratio M are high (when plotted in the region Y), it is diagnosed as a contamination state in which a large amount of inorganic scale is adhered.

  If the type of the contamination state is diagnosed by the above method, a cleaning process for cleaning the separation membrane is performed by appropriately selecting a cleaning chemical or a cleaning order used for cleaning the separation membrane according to the contamination state. For example, if it is an organic matter-based contamination type plotted in the region Z, alkali cleaning or cleaning using an organic solvent or polyol is effective, and a combined contamination type plotted in the region W If present, a combination of alkali cleaning and nitric acid cleaning is effective. In addition, for an inorganic-based contamination type plotted in the region Y, acid cleaning using oxalic acid or hydrochloric acid, or a combination of acid cleaning and alkali cleaning is effective.

  In the operation management method of the membrane separation apparatus incorporating such a diagnostic process and a washing process, the separation membrane is further modified by appropriately changing the recovery rate of the permeate collected from the membrane separation apparatus, the amount of additive chemical added, the order of addition, etc. You may take measures to prevent contamination.

  Note that the present invention focuses on the relationship between the change in the surface roughness of the first membrane surface of the separation membrane and the amount of contaminants attached, and is technically used to diagnose the contamination state of the separation membrane. Creating a drawing from numerical formulas that express changes in surface roughness, changes in surface roughness, etc. is a means of visualizing these relationships, and the diagnostic method is the above formula It is not restricted to what uses.

  Next, based on an Example, this invention is demonstrated in more detail.

[Example 1]
The separation membrane is composed of a spiral membrane module (NTR-759HR, manufactured by Nitto Denko Corporation) having a reverse osmosis membrane which is a composite membrane having a skin layer composed of aromatic polyamide on a polysulfone-based support layer. Using the membrane separation apparatus, wastewater treatment was performed by a membrane separation method using machine manufacturing factory wastewater as the liquid to be treated. The wastewater contained a TOC component having a concentration of 4.6 mg / L, a calcium component having a concentration of 80 mg / L, and silica having a concentration of 16 mg / L, and the pH was 9.5. Moreover, the pure water permeation | transmission flow rate of the membrane separation apparatus by which an unused membrane module is arrange | positioned is 1.0-1.2m < ³ > / (m < ² > * day) at the operating pressure of 1.2 MPa, and the operating pressure of 1.2 MPa. When the wastewater treatment was performed, the contaminants adhered to the reverse osmosis membrane, and the permeation flow rate decreased to 0.19 m ³ / (m ² · day). Therefore, the separation membrane on which the membrane module was disassembled and the contaminants adhered was designated as a contamination membrane A.

  Next, the surface of the skin layer, which is the first film surface of the contamination film A, is measured using an ultra-deep color shape measurement microscope (manufactured by Keyence Corporation, VK-9500). The change in surface roughness of the contaminated film A was quantified as the surface area ratio V of A. Further, using a fluorescent X-ray analyzer (manufactured by Philips, PW1404), the total adhesion amount ratio M of silica and calcium as an inorganic substance was determined by the method described above.

Further, the amount of the surfactant adhered as an organic substance was determined, and a part of the contaminated film A was immersed in an aqueous sodium hydroxide solution (pH 12) for 60 minutes and treated while applying 45 kHz ultrasonic waves. The liquid alkylphenyl ether type nonionic surfactant concentration obtained by this treatment was measured with an APE-ELISA kit (manufactured by Takeda Pharmaceutical Co., Ltd.), and the value obtained by dividing the value by the surface area of the contaminated membrane A subjected to the measurement The amount of ionic surfactant adhered (mg / cm ² ) was used.

  On the basis of the obtained surface area ratio V and inorganic matter adhesion ratio M, the point A indicating the contamination state of the contaminated film A is plotted in the two-dimensional plane plot diagram shown in FIG. . Further, when the measured values are plotted on a three-dimensional diagram in which the surface area ratio V is the X axis, the inorganic substance adhesion amount M is the Y axis, and the nonionic surfactant adhesion amount is the Z axis, the three-dimensional plot diagram shown in FIG. Obtained.

  From these plots, it was diagnosed that the contaminated film A is an inorganic-based contamination type containing a large amount of scale substance and that there is a slight contamination by a nonionic surfactant. Therefore, the contaminated film A was cleaned by a combination of acid cleaning using a 2% by mass aqueous solution of citric acid and sodium hydroxide (pH 12) and alkali cleaning.

Cleaning was performed by immersing the contaminated film A in each cleaning solution for 24 hours, and a permeation flow rate test using pure water was performed after the cleaning with each cleaning solution to confirm the effect of removing contaminants. In Example 1,
The permeation flow rate after acid cleaning is 0.8 m ³ / (m ² · day), and the permeation flow rate after alkali cleaning is 0.98 m ³ / (m ² · day), and the permeation flow rate is restored to the same level as the new membrane. It was.

[Example 2]
The test was conducted under the same conditions as in Example 1 except that a simulated wastewater containing bovine serum protein (BSA) having a molecular weight of about tens of thousands of tens of thousands mg / L was used as the liquid to be treated instead of the wastewater from the machine manufacturing factory. As a result of continuing the treatment of the simulated waste water, contaminants adhered to the reverse osmosis membrane, and the permeation flow rate decreased to 0.75 m ³ / (m ² · day). Therefore, the membrane module was disassembled and the separation membrane to which the contaminant was attached was taken out and used as the contamination membrane B.

The surface of the skin layer, which is the first film surface of the contaminated film B, is measured by the same method as in Example 1, and the surface area ratio V indicating the change in surface roughness of the contaminated film B and the adhesion amount ratio M of the inorganic substance. When the point B indicating the contamination state of the contamination film B is plotted in the two-dimensional plane plot diagram shown in FIG. 7, the point B is plotted in the region Z. Moreover, the nonionic surfactant adhesion amount was also measured by the same method as in Example 1, and plotted in the three-dimensional plot diagram shown in FIG. From these plots, the contaminated film B was diagnosed as an organic matter-based contamination type mainly composed of organic matter and substantially free from contamination by nonionic surfactants. Therefore, the contaminated film B was alkali washed with sodium hydroxide (pH 12). Alkali washing was carried out in the same manner as in Example 1, and when a permeation flow rate test using pure water was performed after the completion of washing, the permeation flow rate after washing was 1.06 m ³ / (m ² · day).

[Example 3]
The test was performed under the same conditions as in Example 1 except that a simulated wastewater containing an organic substance source mainly composed of glucose at a concentration of 10 mg / L was used as the liquid to be treated instead of the wastewater from the machine manufacturing factory. The simulated waste water had a TOC concentration of 4 mg / L, a nitrogen concentration of 0.4 mg / L, a phosphorus concentration of 0.04 mg / L, and a calcium concentration of 50 mg / L. As a result of continuing the treatment of the simulated waste water, contaminants adhered to the reverse osmosis membrane, and the permeation flow rate decreased to 0.67 m ³ / (m ² · day). Therefore, the membrane module was disassembled and the separation membrane to which the contaminants adhered was taken out and used as the contamination membrane C.

  The surface of the skin layer, which is the first film surface of the contaminated film C, is measured by the same method as in Example 1, and the surface area ratio V indicating the change in surface roughness of the contaminated film C and the inorganic substance adhesion amount ratio M When the point C indicating the contamination state of the contamination film C is plotted in the two-dimensional plane plot diagram shown in FIG. 7, the point C is plotted in the region Z. Moreover, the nonionic surfactant adhesion amount was also measured by the same method as in Example 1, and plotted in the three-dimensional plot diagram shown in FIG. From these plots, the contamination film C was diagnosed as an organic matter-based contamination type mainly composed of organic matter and substantially free from contamination by nonionic surfactants.

Since glucose is thought not to decrease the permeation flow rate, it was considered that the main contaminants of the contaminated membrane C were mainly microorganisms among organic substances. Therefore, the contaminated film C was alkali washed with sodium hydroxide (pH 12). Alkali washing was carried out in the same manner as in Example 1, and when a permeation flow rate test using pure water was performed after the completion of washing, the permeation flow rate after washing was 1.02 m ³ / (m ² · day).

[Example 4]
Spiral membrane with reverse osmosis membrane (composite membrane with cross-linked polyamide skin) manufactured by Toray Industries, Ltd. as membrane separator, using dye material production plant wastewater instead of machine production plant wastewater as the liquid to be treated The same test as in Example 1 was performed except that the module (SU-720) was used. The wastewater contains a TOC component having a concentration of 1.82 mg / L, aluminum (Al), silica (Si), phosphorus (P), calcium (Ca), and iron (Fe), and has a conductivity of 87 μS / cm, pH Was 6.0. Moreover, the pure water permeation | transmission flow rate of the membrane separation apparatus by which an unused membrane module is arrange | positioned is the same as the membrane separation apparatus of Example 1, As a result of performing the test similar to Example 1, the permeation | transmission flow rate is set to 0. It decreased to 47 m ³ / (m ² · day). Therefore, the membrane module was disassembled and the separation membrane to which the contaminants adhered was taken out and used as the contamination membrane D.

  The surface of the skin layer, which is the first film surface of the contaminated film D, is measured by the same method as in Example 1, and the surface area ratio V indicating the change in surface roughness of the contaminated film D and the inorganic substance adhesion amount ratio M When the point D indicating the contamination state of the contamination film D was plotted on the two-dimensional plane plot diagram shown in FIG. 7, the point D was plotted in the region W. Moreover, the nonionic surfactant adhesion amount was also measured by the same method as in Example 1, and plotted in the three-dimensional plot diagram shown in FIG. From these plots, it was diagnosed that the contaminated film D is a combined contamination type in which an organic substance and an inorganic substance are combined, and there is a slight contamination by a nonionic surfactant.

Therefore, the contaminated film D was washed with sodium hydroxide (pH 12), a 5% by mass nitric acid aqueous solution, and then sodium hydroxide (pH 12) in this order. Washing was carried out in the same manner as in Example 1, and a permeation flow rate test using pure water was carried out after the completion of washing. As a result, the permeation flow rate after washing recovered to 1.10 m ³ / (m ² · day).

[Example 5]
Spiral type membrane with reverse osmosis membrane (composite membrane with wholly aromatic polyamide-based skin layer) manufactured by Nitto Denko Corporation as membrane separator, using city water as the liquid to be treated instead of machine factory wastewater The same test as in Example 1 was performed except that the module (ES-20) was used. The liquid to be treated contained a TOC component having a concentration of 0.5 mg / L and aluminum having a concentration of 0.08 mg / L, and the pH was 6.0. Moreover, the pure water permeation | transmission flow rate of the membrane separation apparatus by which an unused membrane module is arrange | positioned is 1.0-1.2m < ³ > / (m < ² > * day) at the operating pressure of 0.75Mpa, and waste water treatment is the operating pressure. Was carried out at 0.75 Mpa instead of 1.2 Mpa. As a result, the permeation flow rate decreased to 0.5 m ³ / (m ² · day). Therefore, the membrane module was disassembled and the separation membrane to which the contaminants adhered was taken out and used as the contamination membrane E.

  The surface of the skin layer, which is the first film surface of the contaminated film E, is measured by the same method as in Example 1, and the surface area ratio V indicating the change in surface roughness of the contaminated film E and the adhesion amount ratio M of the inorganic substance. When the point E indicating the contamination state of the contamination film E is plotted on the two-dimensional plane plot diagram shown in FIG. 7, the point E is plotted in the region Z. Moreover, the nonionic surfactant adhesion amount was also measured by the same method as in Example 1, and plotted in the three-dimensional plot diagram shown in FIG. From these plots, it was diagnosed that the contaminated film E was an organic matter-based contamination type and was substantially free from contamination by nonionic surfactants. Contamination film E was considered to be contaminated with aluminum hydroxide because the TOC concentration of the liquid to be treated was a low concentration less than 1 mg / L.

For this reason, the contaminated membrane E was washed in the same manner as in Example 1 using sodium hydroxide (pH 12), and after the washing was completed, the permeate collection rate was changed from 90% to 70%. Even if the process was continued for the same period as before the change, the permeation flow rate was 0.8 m ³ / (m ² · day), and a decrease in the permeation flow rate could be suppressed.

[Example 6]
Instead of the wastewater of Example 1 as the liquid to be treated, another machine manufacturing factory wastewater containing 5.3 mg / L of TOC component and 134 mg / L of calcium component was used, and reverse osmosis made by Nitto Denko Corporation as a membrane separator. The same test as in Example 1 was performed except that a spiral membrane module (LF-10) provided with a membrane (a composite membrane obtained by combining a wholly aromatic polyamide and a polyvinyl alcohol-based material) was used. The pure water permeation flow rate of the membrane separation apparatus in which unused membrane modules are arranged is 1.0 to 1.2 m ³ / (m ² · day) at an operating pressure of 1.2 Mpa, and the operating pressure is 1.2 Mpa. As a result of the waste water treatment, the permeation flow rate was reduced to 0.62 m ³ / (m ² · day). Therefore, the membrane module was disassembled and the separation membrane to which the contaminants adhered was taken out and used as the contamination membrane F.

  The surface of the skin layer, which is the first film surface of the contaminated film F, is measured by the same method as in Example 1, and the surface area ratio V indicating the change in the surface roughness of the contaminated film F and the inorganic matter adhesion ratio M. When the point F indicating the contamination state of the contamination film F is plotted in the two-dimensional plane plot diagram shown in FIG. 7, the point F is plotted in the region W. Moreover, the nonionic surfactant adhesion amount was also measured by the same method as in Example 1, and plotted in the three-dimensional plot diagram shown in FIG. From these plots, it was diagnosed that the contaminated film F is a binding type contamination type, but is not substantially contaminated by a nonionic surfactant.

In Example 6, since the calcium ion concentration of the treatment liquid is high, the treatment liquid is deposited and removed as calcium carbonate before being processed by the membrane separation device, and the calcium concentration of the treatment liquid supplied to the membrane separation device is determined. When the treatment time was 38 mg / L, the permeation flow rate was 0.78 m ³ / (m ² · day) even if the treatment was continued for the same period as the treatment time before diagnosis, and a decrease in the permeation flow rate could be suppressed.

[Example 7]
Instead of the wastewater of Example 1 as the liquid to be treated, a simulated wastewater containing an alkylphenyl ether type nonionic surfactant (polyoxyethylene (8.5) nonylphenyl ether) at a concentration of 10 mg / L was used. The test was performed under the same conditions as in Example 1. As a result of continuing the treatment of the simulated waste water, contaminants adhered to the reverse osmosis membrane, and the permeation flow rate decreased to 0.4 m ³ / (m ² · day). Therefore, the membrane module was disassembled and the separation membrane with the contaminants attached was taken out and used as the contamination membrane G.

  The surface of the skin layer, which is the first film surface of the contaminated film G, is measured by the same method as in Example 1, and the surface area ratio V indicating the change in surface roughness of the contaminated film G and the adhesion amount ratio M of the inorganic substance. When the point G indicating the contamination state of the contamination film G is plotted in the two-dimensional plane plot diagram shown in FIG. 7, the point G is plotted in the region Z. Moreover, the nonionic surfactant adhesion amount was also measured by the same method as in Example 1, and plotted in the three-dimensional plot diagram shown in FIG. From these plots, it was diagnosed that the contaminated film G is an organic matter-based contamination type mainly composed of organic matter and a strong contamination by a nonionic surfactant.

If the contamination with a nonionic surfactant is mild, the membrane performance can be recovered by conventional alkali cleaning such as sodium hydroxide. However, in the case of strong contamination, it is better to use a polyol or the like (International publication) (See pamphlet of WO2004-0776040). Therefore, referring to the pamphlet of International Publication No. WO2004-0776040, the contamination film G is the same as in Example 1 using a solution mixed with a sodium hydroxide aqueous solution (pH 12) so that the propylene glycol concentration becomes 50% by mass. When the permeation flow rate test using pure water was performed after the washing was completed, the permeation flow rate after washing recovered to 1.08 m ³ / (m ² · day).

[Comparative Example 1]
The contamination film A of Example 1 was periodically cleaned with sodium hydroxide (pH 12) without confirming the contamination state. However, the permeation flow rate after washing was 0.28 m ³ / (m ² · day), and the permeation flow rate could not be recovered by alkali washing.

[Comparative Example 2]
The contamination film B of Example 2 was washed with a 0.1 mass% oxalic acid aqueous solution without confirming the contamination state. However, the permeation flow rate after washing is 0.72 m ³ / (m ² · day), and the permeation flow rate cannot be recovered by acid washing. Rather, polymer organic substances such as proteins are insolubilized by acid and permeate. The flow rate decreased.

[Comparative Example 3]
The contamination film C of Example 3 was washed with a 0.1 mass% oxalic acid aqueous solution without confirming the contamination state. However, the permeation flow rate after washing was 0.60 m ³ / (m ² · day), and the permeation flow rate could not be recovered by acid washing, and the permeation flow rate was rather lowered as in Comparative Example 2.

[Comparative Example 4]
The contamination film D of Example 4 was washed with sodium hydroxide (pH 12), 0.1% by weight oxalic acid aqueous solution, and sodium hydroxide (pH 12) without confirming the contamination state. However, the permeation flow rate after washing was 0.65 m ³ / (m ² · day), and the permeation flow rate could not be recovered.

[Comparative Example 5]
The contamination film G of Example 7 was washed with sodium hydroxide (pH 12), 0.1% by weight without confirming the contamination state. However, the permeation flow rate after washing was 0.80 m ³ / (m ² · day), and the permeation flow rate could not be sufficiently recovered.

  Thus, in Examples 1 to 7, the contamination state of the separation membrane is diagnosed, and an appropriate cleaning method or operation state of the membrane separation device is selected to effectively remove the contamination of the separation membrane, or the separation membrane. It was possible to prevent contamination. However, in Comparative Examples 1 to 5 in which the separation membrane was cleaned without diagnosing the contamination state of the separation membrane, effective cleaning could not be performed, and as a result, the degradation of the separation membrane was advanced.

  INDUSTRIAL APPLICABILITY The present invention can be used to improve the efficiency and optimization of the operation management of a membrane separator used in a pure water production apparatus or the like.

It is a figure which shows the spiral type reverse osmosis membrane module which comprises a membrane separator. It is a cross-sectional schematic diagram of the reverse osmosis membrane contained in the said membrane module. It is an expanded cross-sectional schematic diagram of the said reverse osmosis membrane. It is a schematic diagram which shows the adhesion condition of the contaminant which adheres to the 1st film | membrane surface of a reverse osmosis membrane. It is a schematic diagram which shows the adhesion condition of the contaminant which adheres to the 1st film | membrane surface of a reverse osmosis membrane. It is a schematic diagram which shows the adhesion condition of the contaminant which adheres to the 1st film | membrane surface of a reverse osmosis membrane. FIG. 3 is a two-dimensional plot created in accordance with the present invention. FIG. 3 is a three-dimensional plot created according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Membrane module 10 Membrane 11 Reverse osmosis membrane 12 Skin layer 12s First membrane surface 13s Second membrane surface 13 Support layer 20 Spacer 30 Liquid collection tube 40 Permeate spacer

Claims (14)

A separation having a first film surface facing a liquid to be treated containing impurities, and a second film surface opposite to the first film surface and facing a permeated liquid from which impurities have been removed from the liquid to be treated A method for diagnosing the contamination state of a membrane separation device comprising a membrane,
A measurement step of measuring the change in surface roughness of the first film surface and the amount of inorganic matter adhered to the first film surface to obtain respective measurement values;
After the measurement step, the measured values obtained in the measurement step are plotted on a plan view with the change in surface roughness of the first film surface and the inorganic substance adhesion amount as coordinate axes, respectively, and a two-dimensional plot diagram Provide a two-dimensional plotting process to create
Based on the measured values shown in the two-dimensional plot, the value of the change in surface roughness is lower than the first predetermined reference value, and the value of the inorganic substance adhesion amount is lower than the second predetermined reference value. If it is low, the main contaminant is diagnosed as an organic substance, and the value of the change in surface roughness is lower than the first predetermined reference value, while the value of the inorganic substance adhesion amount is the second predetermined reference value. when enhanced diagnoses and type of organic material and the inorganic material is bonded pollution, further, the value of the change in the surface roughness is higher than the first predetermined reference value, and the value of the inorganic deposition amount A method for diagnosing a contamination state of a membrane separation apparatus, comprising a diagnosis step of diagnosing that the main contaminant is an inorganic substance when the second predetermined reference value is higher. In the diagnostic step, based on the measurement value shown in the two-dimensional plot, the value of the change in surface roughness is lower than the first predetermined reference value in the two-dimensional plot, and the A region where the value of the inorganic matter adhesion amount is lower than the second predetermined reference value is defined as the first region, and the value of the change in surface roughness is lower than the first predetermined reference value, A region having a value higher than the second predetermined reference value is defined as a second region, and the change value of the surface roughness is higher than the first predetermined reference value, and the value of the inorganic substance adhesion amount. 2. The method for diagnosing a contamination state of a membrane separation apparatus according to claim 1, further comprising: classifying an area higher than the second predetermined reference value as a third area. In the measurement step, a change in surface roughness of the first film surface, an inorganic material adhesion amount adhered to the first film surface, and an organic material adhesion amount adhered to the first film surface are measured to Get the measured value,
After said measuring step, and a change in the surface roughness, and the inorganic adhesion amount, a three to create the measurement value three-dimensional plot by plotting the organic matter deposition amount, the three-dimensional view of the coordinate axes order Establish original plotting process,
In addition to the diagnostic process, the diagnostic method of the contamination state of the membrane separation apparatus according to claim 1, further comprising a diagnostic step of diagnosing the contamination state of the separation membrane by using the three-dimensional plot. In the diagnostic step based on the two-dimensional plot diagram, based on the measured value shown in the two-dimensional plot diagram, the value of the change in surface roughness of the two-dimensional plot diagram is the first predetermined reference value. A region that is lower and has a value of the inorganic adhesion amount lower than the second predetermined reference value is defined as a first region, and a value of the change in surface roughness is lower than the first predetermined reference value. A region where the value of the inorganic substance adhesion amount is higher than the second predetermined reference value is a second region, and further, the value of the change in surface roughness is higher than the first predetermined reference value, and The method for diagnosing a contamination state of a membrane separation apparatus according to claim 3 , comprising classifying a region having a value of the inorganic substance adhesion amount higher than the second predetermined reference value as a third region. In the diagnostic step, when the organic substance adhesion amount serving as the coordinate axis of the three-dimensional plot diagram is a nonionic surfactant adhesion amount, the measurement value shown in the two-dimensional plot diagram is in the third region, Further, when the measured value of the organic substance adhesion amount shown in the three-dimensional plot diagram is lower than a third predetermined reference value , the contamination state of the membrane separation device is an inorganic-based contamination type, and non-ionized The diagnosis method of the contamination state of the membrane separation apparatus of Claim 4 which diagnoses that there exists mild contamination by surfactant. In the diagnostic step, when the organic substance adhesion amount serving as the coordinate axis of the three-dimensional plot diagram is a nonionic surfactant adhesion amount, the measurement value shown in the two-dimensional plot diagram is in the first region, Further, when the measured value of the nonionic surfactant adhesion amount shown in the three-dimensional plot diagram is 0, the contamination state of the membrane separation device is an organic matter-based contamination type, and the nonionic surfactant activity 5. The method for diagnosing a contamination state of a membrane separation device according to claim 4 , wherein diagnosis is substantially made of no contamination by an agent. In the diagnostic step, when the organic matter adhesion amount serving as the coordinate axis of the three-dimensional plot diagram is a nonionic surfactant adhesion amount, the measurement value shown in the two-dimensional plot diagram is in the second region, Further, when the measured value of the nonionic surfactant adhesion amount shown in the three-dimensional plot diagram is lower than the third predetermined reference value , the contamination state of the membrane separator is combined with an organic substance and an inorganic substance. The method for diagnosing a contamination state of a membrane separation apparatus according to claim 4 , wherein the contamination type of the membrane separation apparatus is diagnosed as having a slight contamination by a nonionic surfactant. In the diagnostic step, when the organic matter adhesion amount serving as the coordinate axis of the three-dimensional plot diagram is a nonionic surfactant adhesion amount, the measurement value shown in the two-dimensional plot diagram is in the second region, Further, when the measured value of the nonionic surfactant adhesion amount shown in the three-dimensional plot diagram is 0, the contamination state of the membrane separation device is a combined contamination type in which organic substances and inorganic substances are combined. The method for diagnosing a contamination state of a membrane separation apparatus according to claim 4 , wherein the diagnosis is made substantially without contamination by a nonionic surfactant. In the diagnostic step, when the organic substance adhesion amount serving as the coordinate axis of the three-dimensional plot diagram is a nonionic surfactant adhesion amount, the measurement value shown in the two-dimensional plot diagram is in the first region, Further, when the measured value of the nonionic surfactant adhesion amount shown in the three-dimensional plot diagram is higher than the third predetermined reference value , the contamination state of the membrane separation device is determined as an organic matter-based contamination type. 5. The method for diagnosing a contamination state of a membrane separation device according to claim 4 , wherein there is a diagnosis of strong contamination by a nonionic surfactant. The method for diagnosing a contamination state of a membrane separation apparatus according to any one of claims 1 to 9 , wherein the separation membrane is a reverse osmosis membrane. The diagnosis method of a contamination state of a membrane separation apparatus according to claim 10 , wherein the reverse osmosis membrane includes a skin layer made of polyamide. The reverse osmosis membrane is a composite membrane comprising the skin layer and a support layer composed of a porous body and supporting the skin layer,
The method for diagnosing a contamination state of a membrane separation device according to claim 11 , wherein the skin layer is located on the first membrane surface side and the support layer is located on the second membrane surface side. A diagnostic step for diagnosing the contamination state of the separation membrane having a first membrane surface facing the liquid to be treated containing impurities and a second membrane surface opposite to the first membrane surface; and a result of the diagnostic step A cleaning process for cleaning the separation membrane based on
A method for cleaning a membrane separation apparatus, wherein the contamination state of the separation membrane is diagnosed by the diagnosis method for a contamination state of the membrane separation apparatus according to any one of claims 1 to 12 in the diagnosis step. In the diagnosis step, the contamination state of the separation membrane is diagnosed by the method for diagnosing the contamination state of the membrane separation apparatus according to claim 4 , and the measured value shown in the two-dimensional plot diagram is in the first region. Is acid cleaning, or a combination of acid cleaning and alkali cleaning, and when the measured value shown in the two-dimensional plot is in the second region, a combination of alkali cleaning and acid cleaning, and the two-dimensional plot. The membrane separation apparatus cleaning method according to claim 13 , wherein when the measured value shown in the figure is in the third region, alkali cleaning or cleaning using an organic solvent or polyol is performed.

Images