WO2020158895A1 - Method for determining cleaning conditions of filter - Google Patents

Method for determining cleaning conditions of filter Download PDF

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Publication number
WO2020158895A1
WO2020158895A1 PCT/JP2020/003540 JP2020003540W WO2020158895A1 WO 2020158895 A1 WO2020158895 A1 WO 2020158895A1 JP 2020003540 W JP2020003540 W JP 2020003540W WO 2020158895 A1 WO2020158895 A1 WO 2020158895A1
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Prior art keywords
value
cleaning
difference
filter
product
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PCT/JP2020/003540
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French (fr)
Japanese (ja)
Inventor
豊 五條
剛英 吉田
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旭化成株式会社
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Publication of WO2020158895A1 publication Critical patent/WO2020158895A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D65/00—Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes
    • B01D65/02—Membrane cleaning or sterilisation ; Membrane regeneration
    • B01D65/06—Membrane cleaning or sterilisation ; Membrane regeneration with special washing compositions
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis

Definitions

  • the present invention relates to a method for determining filter cleaning conditions. Specifically, when cleaning a filter used for purification of raw water with a cleaning liquid containing hydrogen peroxide, a filter cleaning for obtaining a maximum cleaning effect with a minimum amount of cleaning liquid and a minimum cleaning time. Regarding the method of determining conditions.
  • Patent Document 1 proposes a cleaning agent for a separation membrane containing hydroxydicarboxylic acid, hydrogen peroxide, and a heavy metal compound.
  • a washing liquid containing hydrogen peroxide as proposed in Patent Document 1 can be preferably used.
  • the cleaning of the filter in the prior art is performed, for example, when the water permeation amount of the filter is reduced to a predetermined value, when the transmembrane pressure difference of the filter is increased to a predetermined value, or periodically, using a cleaning solution having a constant concentration. It was usually done on time.
  • the concentration of the cleaning solution, the cleaning time, or both may be too small for the degree of contamination of the filter, and the desired cleaning effect may not be obtained, or The concentration of the cleaning liquid, the cleaning time, or both of them become excessive with respect to the degree of contamination of the filter, and although the desired cleaning effect is obtained, the cleaning liquid and the cleaning time may be wasted.
  • An object of the present invention is to provide a method for determining filter washing conditions for obtaining the maximum washing effect with the minimum washing liquid and the shortest washing time.
  • a method for determining filter washing conditions for washing a filter used for purification of raw water with a washing liquid containing hydrogen peroxide When the hydrogen peroxide concentration in the cleaning liquid is C, the cleaning time is T, the water permeability of the filter before cleaning is P1, and the water permeability after cleaning is P2, A method for determining filter cleaning conditions, comprising: an estimation step of a product CT value from a difference (P2-P1) value; and an estimation step of estimating a difference (P2-P1) value from the product CT value.
  • ⁇ Aspect 5> The method for determining filter washing conditions according to Aspect 4, wherein the explanatory variable is divided into a plurality of regions, and a regression equation is set for each region of the explanatory variable.
  • the estimating step is a step of estimating a product CT value from a difference (P2-P1) value, The method for determining filter cleaning conditions according to any one of aspects 1 to 5, wherein the cleaning time T is determined from a predetermined hydrogen peroxide concentration C based on the estimated product CT value.
  • the estimating step is a step of estimating a product CT value from the difference (P2-P1) value, The method for determining filter cleaning conditions according to any one of aspects 1 to 5, wherein the hydrogen peroxide concentration C is determined from a predetermined cleaning time T based on the estimated product CT value.
  • the estimating step is a step of estimating a difference (P2-P1) value from the product CT value, The filter washing conditions according to any one of aspects 1 to 5, wherein the water permeability P1 before washing is determined from the water permeability P2 after a predetermined washing based on the estimated difference (P2-P1) value. How to decide.
  • the estimating step is a step of estimating a difference (P2-P1) value from the product CT value, Determination of the filter cleaning conditions according to any one of aspects 1 to 5, wherein the permeation rate P2 after cleaning is determined from the detected permeation rate P1 value based on the estimated difference (P2-P1) value.
  • Method. ⁇ Aspect 10> The filter washing conditions according to any one of Aspects 1 to 9, wherein the filter used for purifying the raw water is a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, or a reverse osmosis membrane. How to decide.
  • ⁇ Aspect 11> The method for determining filter washing conditions according to any one of Aspects 1 to 10, wherein the cleaning liquid is a hydrogen peroxide solution or a cleaning liquid containing hydrogen peroxide and an iron compound.
  • ⁇ Aspect 12> The method for determining filter washing conditions according to Aspect 11, wherein the cleaning liquid containing hydrogen peroxide and an iron compound further contains hydroxydicarboxylic acid.
  • ⁇ Aspect 13>> The method for determining filter washing conditions according to any one of Aspects 1 to 12, wherein the raw water is seawater or river water.
  • FIG. 1 is a schematic diagram showing an example of the configuration of a raw water purification apparatus to which the present invention can be suitably applied.
  • FIG. 2 is a schematic diagram showing an example of the configuration of a seawater desalination apparatus, which is an aspect of a raw water purification apparatus to which the present invention can be suitably applied.
  • FIG. 3 is a graph showing the relationship between the difference (P2-P1) and the product CT value obtained in Experimental Example 1.
  • FIG. 4 is a graph showing the relationship between the difference (P2-P1) and the product CT value obtained in Experimental Example 2.
  • FIG. 5 is a graph showing the relationship between the difference (P2-P1) and the product CT value obtained in Experimental Example 3.
  • FIG. 6 is a graph showing the relationship between the difference (P2-P1) and the product C'T value obtained in Experimental Example 4.
  • the method for determining the filter washing conditions of the present invention is A method for determining filter cleaning conditions, for cleaning a filter used for purification of raw water with a cleaning solution containing hydrogen peroxide,
  • the hydrogen peroxide concentration in the cleaning liquid is C
  • the cleaning time is T
  • the water permeability of the filter before cleaning is P1
  • the water permeability after cleaning is P2
  • the method includes any one of the step of estimating a product CT value from the difference (P2-P1) value and the step of estimating a difference (P2-P1) value from the product CT value.
  • the method for determining filter washing conditions of the present invention is preferably applied when washing a filter used for purifying raw water.
  • raw water include seawater, river water, lake water, groundwater, sewage, and industrial wastewater.
  • Purification of seawater includes, for example, removing impurities from seawater to produce seawater for breeding seafood, desalinating seawater, and the like.
  • Purification of river water, lake water, groundwater, sewage, and industrial wastewater includes, for example, removing impurities from these raw water to produce drinking water. The filter will be described later.
  • the present inventors have examined whether or not a legal relationship can be found between the type and concentration of the cleaning liquid, the cleaning time, and the water permeation amount of the filter before and after cleaning. , Detailed examination was done. As a result, when a cleaning liquid containing hydrogen peroxide was used as the cleaning liquid, the difference between the water permeation amount P2 after cleaning the filter and the water permeation amount P1 before cleaning (P2-P1) and the hydrogen peroxide concentration C in the cleaning liquid It has been found that there is a high degree of correlation between the product and the product CT of the cleaning time T.
  • a graph plotting the difference (P2-P1) on the horizontal axis and the product CT on the vertical axis is a single line or curve with a high correlation. Get on.
  • the method includes any one of the step of estimating a product CT value from the difference (P2-P1) value and the step of estimating a difference (P2-P1) value from the product CT value.
  • the estimation step in the present invention is The product CT value of the hydrogen peroxide concentration C in the cleaning liquid and the cleaning time T, It is preferable to use a relational expression between the difference (P2-P1) between the water permeability P2 of the filter after washing and the water permeability P1 of the filter before washing.
  • the relational expression used in the estimation step is, for example, a regression expression obtained by the maximum likelihood estimation in which one of the product CT value and the difference (P2-P1) value is the explanatory variable and the other is the objective variable. It is preferable.
  • a regression equation obtained by the maximum likelihood estimation in which one of the product CT value and the difference (P2-P1) value is the explanatory variable and the other is the objective variable.
  • a preferred regression equation will be described by taking the case where the difference (P2-P1) value is the explanatory variable and the product CT value is the objective variable, but the product CT value is the explanatory variable and the difference (P2-P1) value is It should be understood that a regression equation with the objective variable as is also disclosed.
  • the relational expression in the present invention may be, for example, a regression expression obtained by maximum likelihood estimation using a difference (P2-P1) value as an explanatory variable and a product CT value as an objective variable.
  • CT A(P2-P1) B +C (1)
  • A, B, and C are coefficients respectively.
  • ⁇ May be a formula represented by the form.
  • the maximum likelihood estimation for obtaining the mathematical expression (1) may be the least squares method, for example. In the least squares method, the coefficients A, B, and C are determined so that the sum of squares error between the measured value of the product CT value, which is the objective variable, and the product CT value estimated by Equation (1) becomes the minimum.
  • the correlation coefficient R 2 in this case can be 0.80 or more, further 0.85 or more, and particularly 0.90 or more.
  • the unit of difference (P2-P1) value is% pt (percent point)
  • the unit of product CT is As the mass% ⁇ h
  • the coefficient A is approximately 1.0 ⁇ 10 ⁇ 8 or more and 5.0 ⁇ 10 ⁇ 8 or less
  • the coefficient B is approximately 3.0 or more and 6.0 or less
  • the coefficient C is A regression equation showing a high correlation of approximately ⁇ 0.5 or more and +0.5 or less and a correlation coefficient R 2 of approximately 0.90 or more was obtained.
  • a single regression equation may be set over the entire range of the explanatory variable region for which the maximum likelihood estimation is performed, or the explanatory variable may be divided into a plurality of regions and a separate regression equation may be set for each divided region. May be set. If the explanatory variable is divided into a plurality of areas and a separate regression equation is set for each of the divided areas, a lower-order regression equation (where the value of the coefficient B in equation (1) is close to 1) provides more accuracy. A high estimate of Alternatively, the explanatory variable may be divided into a plurality of areas, and a constant set while considering the relational expression for each of the divided areas may be adopted as the objective variable.
  • the regression equation (1) may be used to estimate the difference (P2-P1) value from the known product CT value.
  • the relational expression between the product CT value and the difference (P2-P1) value is preferably updated periodically or at the timing when a significant amount of new data is accumulated, taking into account the new data.
  • the product CT value is the product of the hydrogen peroxide concentration C (mass %) and the cleaning time T(h).
  • the maximum likelihood estimation for obtaining the regression equation as the relational expression between the product CT value and the difference (P2-P1) value, and the range of the product CT value in the estimation step may be within the range of practical cleaning conditions. It is preferable in that the accuracy of estimation can be increased.
  • the product CT value range is preferably 10% by mass or less, more preferably 0.1% by mass or more and 8% by mass or less, and even more preferably 0.5% by mass or more and 6% by mass or more. It is less than or equal to h.
  • the difference (P2-P1) value is the value obtained by subtracting the water permeability P1 (%) before washing from the water permeability P2 (%) after washing when the water permeability of a new filter is 100%.
  • % pt percent point
  • the water permeation rates P1 and P2 before and after the cleaning may each be a value measured or estimated as the water permeation rate, or a converted value from another index such as the transmembrane pressure difference.
  • the maximum likelihood estimation for obtaining the regression equation as the relational expression between the product CT value and the difference (P2-P1) value, and the range of the difference (P2-P1) value in the estimation step are within the range of practical cleaning conditions. Is preferable in that the accuracy of estimation can be increased.
  • the range of the difference (P2-P1) value is preferably 10% pt or more and 80% pt or less, more preferably 20% pt or more and 70% pt or less, and further preferably 30% pt or more and 60% pt or less. ..
  • the value of the water permeation amount P1 before washing the filter is preferably 10% or more, more preferably 15% or more, still more preferably 20% or more.
  • the water permeation rate P2 after filter cleaning if an unnecessarily high water permeation rate is required, it is feared that the consumption of the cleaning liquid and the cleaning time will be unnecessarily increased and the cleaning efficiency will be impaired.
  • the value of the water permeation amount P2 after filter washing may be less than 100%, preferably 95% or less, more preferably 90% or less, and further preferably 85% or less.
  • the method for determining the filter washing conditions of the present invention is Estimating the product CT value from the difference (P2-P1) value (first estimation step), and estimating the difference (P2-P1) value from the product CT value (second estimation step) And an estimation step of any one of the above.
  • the product CT value is estimated from the difference (P2-P1) value.
  • the difference (P2-P1) value may be set, for example, based on the detected value of the water permeation amount P1 before filter cleaning and the desired value of the water permeation amount P2 after cleaning.
  • the detected water permeation amount P1 before filter cleaning may be a value directly measured as the water permeation amount, or a value converted from other measured values such as transmembrane pressure difference, It may be a value empirically estimated from the progress and the like.
  • the water permeability P2 after filter cleaning may be appropriately set in consideration of the recommended range of the difference (P2-P1) value from the viewpoint of estimation accuracy, the recommended range of the P2 value from the viewpoint of cleaning efficiency, and the like. ..
  • the cleaning condition of the filter can be determined based on the product CT value estimated in the first estimation step.
  • the cleaning time T may be determined from the predetermined hydrogen peroxide concentration C.
  • the cleaning time T determined from the predetermined hydrogen peroxide concentration C based on the estimated product CT value the desired post-cleansing water permeation amount P2 is realized without corroding the filter. can do.
  • the hydrogen peroxide concentration C may be determined from the predetermined cleaning time T.
  • the cleaning time T is completed within a predetermined time depending on the operation schedule of the raw water purification facility.
  • the hydrogen peroxide concentration C determined from the predetermined cleaning time T is adopted based on the estimated product CT value to realize a desired post-cleansing water permeation amount P2 within a predetermined time limit. be able to.
  • the difference (P2-P1) value is estimated from the product CT value.
  • the product CT value is set in consideration of, for example, the hydrogen peroxide concentration C set in consideration of filter corrosion prevention, handling safety, and cleaning efficiency, and the operation schedule of the raw water purification equipment. It may be a product of the cleaning time T and the cleaning time T.
  • the filter cleaning condition and the like can be determined.
  • the permeation rate P1 before cleaning may be determined from the desired permeation rate P2 after filter cleaning.
  • a guideline as to how much the pre-washing water permeation amount P1 should be lowered to perform the washing is obtained. be able to.
  • a desired water permeation rate P2 after cleaning may be determined (estimated) from the water permeation rate P1 before filter cleaning.
  • the value of the post-cleaning water permeability P2 obtained when the filter having the known water permeability P1 is cleaned at the predetermined hydrogen peroxide concentration C and the predetermined cleaning time T is highly accurate in advance. It becomes possible to know in.
  • the operating conditions when restarting the raw water purification operation after the end of washing can be appropriately set based on the obtained P2 value, so that the unstable period when restarting the operation can be minimized.
  • the cleaning liquid used in the present invention contains hydrogen peroxide.
  • the cleaning liquid used in the present invention may be a hydrogen peroxide solution (preferably hydrogen peroxide solution) or a cleaning liquid containing hydrogen peroxide and an iron compound.
  • the cleaning liquid containing the hydrogen peroxide and the iron compound may further contain hydroxydicarboxylic acid.
  • the cleaning liquid may further contain, as an optional component, one or more kinds selected from, for example, a surfactant, a chelating agent, a pH adjusting agent, a thickener, an antifoaming agent and a preservative.
  • the concentration of hydrogen peroxide in the cleaning liquid is preferably in the range of 1 mmol/L (0.0034% by mass) or more and 10,000 mmol/L (10 mol/L, 30% by mass) or less. If the concentration of hydrogen peroxide is less than 1 mmol/L, hydrogen peroxide may be consumed before the removal of deposits on the filter is completed, and the cleaning effect may be insufficient. Even if the concentration of hydrogen peroxide exceeds 10,000 mmol/L, there is no problem from the viewpoint of cleaning effect.
  • the concentration of hydrogen peroxide in the cleaning liquid is more preferably in the range of 5 mmol/L (0.017 mass%) or more and 5,000 mmol/L (5 mol/L, 16 mass%) or less, and 10 mmol/L(0 More preferably, it is 0.034 mass% or more and 3,000 mmol/L (3 mol/L, 10 mass%) or less.
  • hydrogen peroxide When preparing the cleaning liquid, hydrogen peroxide may be blended in the form of hydrogen peroxide, or may be blended as a compound that generates hydrogen peroxide in the solution after blending.
  • the compound that generates hydrogen peroxide in the solution include sodium percarbonate and sodium perborate.
  • the cleaning liquid used in the present invention may further contain an iron compound in addition to hydrogen peroxide.
  • the cleaning liquid containing hydrogen peroxide and the iron compound can efficiently clean the filter by the Fenton reaction.
  • the iron compound may be a water-soluble iron salt, and is preferably a salt containing at least one of iron (II) ion and iron (III) ion, more preferably iron (II) ion or It is a chloride containing an iron (III) ion, a sulfate, a nitrate, and the like, and it is particularly preferable to use one or more selected from ferrous chloride and ferric chloride.
  • Ferrous chloride and ferric chloride are both preferable because they are inexpensive and precipitate when an alkali (for example, sodium hydroxide) is added to the cleaning liquid after use and can be easily removed by filtration.
  • an iron salt When an iron salt is used as the iron compound, it may be an anhydrous salt or a hydrated salt.
  • the amount of the iron compound in the cleaning liquid is preferably 0.001 mol or more and 100 mol or less with respect to 1 mol of hydrogen peroxide. If the amount of the iron compound in the cleaning liquid is less than 0.001 mol with respect to 1 mol of hydrogen peroxide, the effect of including the iron compound in the cleaning liquid is not sufficiently expressed, and the Fenton reaction may not be effectively performed. Occurs. On the other hand, if the amount of the iron compound in the cleaning liquid is excessively large, it takes time and cost to process the cleaning liquid waste liquid after the filter cleaning, which is not preferable.
  • the amount of the iron compound in the cleaning liquid is more preferably 0.005 mol or more and 10 mol or less, further preferably 0.01 mol or more and 5 mol or less, and more preferably 0.
  • the amount is particularly preferably 05 mol or more and 1 mol or less, and particularly preferably 0.1 mol or more and 0.5 mol or less.
  • the cleaning liquid used in the present invention may further contain hydroxydicarboxylic acid together with hydrogen peroxide and an iron compound.
  • the cleaning liquid containing hydroxydicarboxylic acid improves the removal efficiency of the inorganic compounds in the filter contaminants.
  • Examples of the hydroxydicarboxylic acid contained in the cleaning liquid include malic acid, tartaric acid, tartronic acid (also known as 2-hydroxymalonic acid), citramalic acid (also known as 2-methylmalic acid), dioxymaleic acid and dioxymalonic acid. And one or more selected from these can be used.
  • the amount of hydroxydicarboxylic acid in the cleaning liquid is preferably 0.001 mol or more and 10,000 mol or less with respect to 1 mol of iron atoms contained in the iron compound. If the amount of hydroxydicarboxylic acid in the cleaning liquid is less than 0.001 mol with respect to 1 mol of iron atom, there is a concern that iron will precipitate during cleaning of the filter. On the other hand, if the amount of hydroxydicarboxylic acid in the cleaning liquid exceeds 10,000 mol per 1 mol of iron atom, there is a concern that the hydroxydicarboxylic acid itself may be oxidatively decomposed, and the organic matter in the filter deposit may be decomposed and removed. Performance may be impaired.
  • the amount of hydroxydicarboxylic acid in the cleaning liquid is more preferably 0.005 mol or more and 1,000 mol or less, and 0.010 mol or more and 100 mol or less, with respect to 1 mol of the iron atom contained in the iron compound.
  • the amount is more preferably 0.015 mol or more and 50 mol or less, and particularly preferably 0.020 mol or more and 10 mol or less.
  • the concentration of an iron compound in terms of iron atom means an equivalent concentration obtained by multiplying the molar concentration of the iron compound by the number of iron atoms contained in the composition formula of the iron compound.
  • concentration of 1 mmol/L ferrous chloride (compositional formula: FeCl 2 ) in terms of iron atoms is 1 mmol/L
  • the iron atom-equivalent concentration of is 2 mmol/L.
  • the amount of hydroxydicarboxylic acid in the cleaning liquid is preferably 0.0001 mol or more and 100 mol or less with respect to 1 mol of hydrogen peroxide. If the amount of hydroxydicarboxylic acid in the cleaning liquid is less than 0.0001 mol with respect to 1 mol of hydrogen peroxide, the effect of cleaning and removing inorganic substances in the filter deposit may be insufficient. When the amount of hydroxydicarboxylic acid in the cleaning liquid is more than 100 mol with respect to 1 mol of hydrogen peroxide, the pH of the cleaning liquid becomes excessively low, which may impair the cleaning effect by the Fenton reaction.
  • the amount of hydroxydicarboxylic acid in the cleaning liquid is more preferably 0.0005 mol or more and 10 mol or less, and further preferably 0.001 mol or more and 1.0 mol or less, relative to 1 mol of hydrogen peroxide. Is particularly preferably 0.003 mol or more and 0.5 mol or less, and particularly preferably 0.005 mol or more and 0.1 mol or less.
  • the surfactant that the cleaning liquid can optionally contain may be any of anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants, and one of these may be used. The above can be used.
  • anionic surfactant examples include soap, sulfuric acid ester of higher alcohol, alkylbenzene sulfonic acid, alkylnaphthalene sulfonic acid, phosphoric acid ester of higher alcohol, and the like;
  • cationic surfactants include primary amine salts, secondary amine salts, tertiary amine salts, quaternary ammonium salts, and the like;
  • amphoteric surfactant include alkyldimethylamine oxide, alkyldimethylamino fatty acid betaine, alkylcarboxymethyl hydroxyethyl imidazolium betaine, and the like;
  • nonionic surfactant examples include polyoxyethylene alkylphenyl ether, polyoxypropylene alkylphenyl ether, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyethylene glycol alkyl ester, ethylene oxide adduct of polypropylene glycol, polypropylene glycol.
  • chelating agent examples include 1-hydroxyethylidene-1,1-diphosphonic acid, aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, hexamethylenediaminetetramethylenephosphonic acid and diethylenetriamine. Pentamethylenephosphonic acid and the like; and their sodium salts, potassium salts, lithium salts, ammonium salts, amine salts, alkanolamine salts and the like.
  • water-soluble organic solvents include alcohols, ketones, ethers, and other polar solvents. Specific examples thereof include alcohols such as methanol, ethanol, n-propanol, i-propanol, t-butanol, and ethylene glycol; ketones such as acetone; ethers such as tetrahydrofuran; , 4-dioxane and the like; other polar solvents include, for example, dimethylformamide and the like.
  • the cleaning liquid used in the present invention is preferably water or a mixed solvent of water and a water-soluble organic solvent, typically water.
  • the pH of the cleaning liquid is preferably in an acidic region in order to maintain a high effect of cleaning and removing the inorganic substances in the filter contaminants.
  • the pH of the cleaning chemicals is preferably 6.0 or less, more preferably 2.0 or more and 5.0 or less, further preferably 2.0 or more and 4.0 or less, and particularly 2.0 or more 3 It may be less than or equal to 0.0.
  • the concentration of the cleaning liquid is set in advance in consideration of the material of the filter to be cleaned and the like, or is appropriately set according to the estimated CT value.
  • a cleaning solution with a set concentration may be prepared each time, but a concentrated cleaning solution (stock solution) containing each component in the cleaning solution in a predetermined ratio is prepared, and the concentrated cleaning solution is diluted according to the set concentration before use. It is convenient.
  • the concentration of the concentrated cleaning solution is 5 mol/L (16% by mass) or more as the concentration of hydrogen peroxide in the concentrated cleaning solution from the viewpoint of convenience of preparation (dilution) of the cleaning solution, safety of handling the concentrated cleaning solution, and the like.
  • the amount is preferably mol/L (43% by mass) or less, more preferably 7.5 mol/L (23% by mass) or more and 10 mol/L (30% by mass) or less.
  • the cleaning method may be circulation cleaning, immersion cleaning, etc., and these may be used in combination. It should be noted that if the cleaning method is different, the cleaning efficiency of the filter is also different. Therefore, the relational expression between the product CT value and the difference (P2-P1) value used in the estimation step should be set for each cleaning method. Is preferred.
  • the filter to which the present invention is applied is a filter used for purification of raw water. Specifically, it may be one or more selected from microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, reverse osmosis membranes and the like.
  • the shape of the filter is arbitrary. For example, it may have a flat film shape, a laminated body, a bellows shape, a wound body, a hollow fiber shape or the like.
  • a hollow fiber membrane module in which a plurality of hollow fiber filters are packaged is preferable because a large membrane area can be secured with a small volume.
  • the filter to which the present invention is applied may be made of any material.
  • it may be a filter made of a fluorine resin, a polysulfone resin, or the like.
  • the fluorine resin include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, perfluoroalkoxy fluororesin, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoride.
  • examples thereof include ethylene copolymers and ethylene-chlorotrifluoroethylene copolymers.
  • the polysulfone-based resin include polysulfone and polyether sulfone.
  • the cleaning liquid used in the present invention contains hydrogen peroxide and has a strong oxidizing power. Therefore, it is desired that the present invention be applied to a filter having high oxidation resistance. Therefore, the present invention is preferably applied to a filter made of a fluororesin. When cleaning a filter made of a fluorine-based resin, even if the concentration C of hydrogen peroxide in the cleaning liquid is increased to about 10% by mass, the possibility of the problem of filter corrosion is maintained low.
  • the filter to which the present invention is applied may typically be, for example, an ultrafiltration membrane or a microfiltration membrane used in a raw water purification apparatus.
  • FIG. 1 shows an example of the configuration of a raw water purification apparatus to which the present invention can be suitably applied.
  • a strainer (12) for capturing and removing relatively coarse solids contained in the raw water (10) to be treated, and an ultrafiltration membrane or a microfiltration membrane After 13), purified water (11) which is purified raw water is stored in a purified water tank (16).
  • a pretreatment device such as a pressure flotation device or a coagulating sedimentation device may be further installed.
  • the raw water purification device may be, for example, a seawater desalination device.
  • FIG. 2 shows an example of the configuration of a seawater desalination apparatus, which is an aspect of a raw water purification apparatus to which the present invention can be preferably applied.
  • a strainer (22) In the seawater desalination apparatus (200) of FIG. 2, a strainer (22), an ultrafiltration membrane or a precision filter for capturing and removing relatively coarse solids contained in seawater (20) which is raw water to be treated. After passing through the filtration membrane (23), the primary filtered water storage tank (24) and the reverse osmosis membrane (25), purified seawater (21) is stored in the freshwater tank (26).
  • a pretreatment device such as a pressure flotation device or a coagulating sedimentation device may be further installed.
  • the ultrafiltration membrane may be, for example, a filter having a pore size of about 1 nm or more and 10 nm or less.
  • the microfiltration membrane may be, for example, a filter having a pore size of about 5 nm or more and 10 ⁇ m or less.
  • INDUSTRIAL APPLICABILITY The present invention can be suitably applied to, for example, the ultrafiltration membrane or the microfiltration membrane (13, 23) used in the above-mentioned raw water purification device (100), seawater desalination device (200) and the like.
  • Example 1 When the ultrafiltration membrane in the seawater desalination apparatus having the configuration shown in FIG. 2 is washed with a washing liquid containing hydrogen peroxide, the product CT of the hydrogen peroxide concentration C and the washing time T and the permeation amount P2 after washing And the relationship between the difference in the amount of permeation of water P1 before washing (P2-P1) was investigated.
  • the seawater desalination apparatus (200) used in Example 1 includes a strainer (22), an ultrafiltration membrane, a primary filtered water storage tank (24), a reverse osmosis membrane (25), and a freshwater tank (26) in this order. Have.
  • the seawater is desalinated by this seawater desalination apparatus, and the permeation rate before washing P1 (%), the hydrogen peroxide concentration C (mass %), and the permeation rate of the ultrafiltration membrane when new are 100%, and
  • the washing time T(h) was varied within the following range, and a total of 17 times of washing were performed.
  • the post-washing water permeation rate P2(%) obtained after each washing was examined, and the horizontal axis indicates the difference (P2- P1) (%pt) and the vertical axis is the product CT (mass %.h).
  • Variable range of water permeability P1 before washing 20% to 90%
  • Variable range of hydrogen peroxide concentration C 0.01% by mass to 10% by mass
  • Variable range of cleaning time T 10 minutes to 24 hours
  • the cleaning solution used was 0.2 mol of ferrous chloride (0.4 mol in terms of iron atom) and 0.04 mol of tartaric acid per 1 mol of hydrogen peroxide.
  • An aqueous solution containing 1 part by weight was prepared at a predetermined hydrogen peroxide concentration, and hydrochloric acid was added to adjust the pH to 2.5 before use.
  • the washing was performed by circulation filtration washing.
  • Example 2 As the cleaning liquid, the cleaning liquid prepared in the same manner as in Experimental Example 1 was used except that tartaric acid was not used. Using this cleaning solution, the permeation rate before cleaning P1 (%), the hydrogen peroxide concentration C (mass %), and the cleaning time T (h) are set, respectively, when the water permeability of the new ultrafiltration membrane is 100%. Washing was performed in the same manner as in Example 1 except that the number of washings performed by varying the amount was 8 in total, and the water permeation rate after washing P2 (%) obtained after each washing was examined. P2-P1) (%pt) and the vertical axis is the product CT (mass %.h). The obtained graph is shown in FIG. From the graph of FIG.
  • Example 3 Hydrogen peroxide concentration when the ultrafiltration membrane in the raw water purification device was washed with a cleaning liquid containing hydrogen peroxide after the river water was purified using the raw water purification device with the configuration shown in FIG.
  • the raw water purification apparatus (100) used in Example 3 has a strainer (12), an ultrafiltration membrane, and a purified water tank (16) in this order.
  • the cleaning liquid the cleaning liquid prepared in the same manner as in Experimental Example 1 was used.
  • the permeation rate before cleaning P1 (%), the hydrogen peroxide concentration C (mass %), and the cleaning time T (h) are set, respectively, when the water permeability of the new ultrafiltration membrane is 100%. Washing was performed in the same manner as in Example 1 except that the number of washings performed by varying the amount was 7 in total, and the permeation rate P2 (%) after washing obtained after each washing was examined. P2-P1) (%pt) and the vertical axis is the product CT (mass %.h). The obtained graph is shown in FIG. From the graph of FIG. 5, it was found that the difference (P2-P1) and the product CT value are on a single smooth curve.
  • Example 4 The same procedure as in Experimental Example 1 except that an aqueous sodium hypochlorite solution was used as the cleaning liquid, and the variable range of the sodium hypochlorite concentration C′ in the cleaning liquid was set to 0.01% by mass to 1.0% by mass. Then, a total of 11 washes were performed, and plotted on a graph in which the horizontal axis represents the difference (P2-P1) and the vertical axis represents the product C'T. The obtained graph is shown in FIG. From the graph of FIG. 6, it was found that in Experimental Example 4 in which the cleaning liquid containing no hydrogen peroxide was used, the correlation between the difference (P2-P1) and the product C′T value was low. Further, with sodium hypochlorite, the recovery rate did not increase even if the C′T value was increased, and a sufficient cleaning effect was not obtained.

Abstract

A method for determining cleaning conditions of a filter, which is utilized for the purpose of cleaning a filter that is used for purification of raw water with use of a cleaning liquid that contains hydrogen peroxide, and which comprises an estimation step that is selected from among a step for estimating the product CT from the difference (P2 – P1) and a step for estimating the difference (P2 – P1) from the product CT, where C is the hydrogen peroxide concentration in the cleaning liquid, T is the cleaning time, P1 is the water permeability before cleaning of the filter, and P2 is the water permeability after cleaning of the filter.

Description

フィルター洗浄条件の決定方法How to determine filter cleaning conditions
　本発明は、フィルター洗浄条件の決定方法に関する。詳しくは、原水の精製に使用されるフィルターを、過酸化水素を含有する洗浄液を用いて洗浄するときに、最小量の洗浄液、及び最短の洗浄時間によって最大の洗浄効果を得るための、フィルター洗浄条件の決定方法に関する。 The present invention relates to a method for determining filter cleaning conditions. Specifically, when cleaning a filter used for purification of raw water with a cleaning liquid containing hydrogen peroxide, a filter cleaning for obtaining a maximum cleaning effect with a minimum amount of cleaning liquid and a minimum cleaning time. Regarding the method of determining conditions.
　海水、河川水、湖沼水、地下水、下水、工業排水等の原水を、例えば精密ろ過膜、限外ろ過膜、逆浸透膜等によって精製する技術が知られている。
　原水を膜ろ過すると、膜孔径を超える大きさの物質（例えば原水中の懸濁物質等）が、ろ過に用いたフィルターに阻止されて、濃度分極が発生し、或いはケーク等を生成する場合がある。これらはフィルターの汚染物質となり、フィルターの細孔を閉塞させ、ろ過抵抗を増大させ、膜間差圧を上昇させて、ろ過流速（透水量）を減少させる。膜間差圧が所定値まで上昇したフィルターは、洗浄によって汚染物質を除去して、ろ過流速を元の値に戻したうえで再利用される。 There is known a technique for purifying raw water such as seawater, river water, lake water, groundwater, sewage, and industrial wastewater using, for example, a microfiltration membrane, an ultrafiltration membrane, a reverse osmosis membrane, or the like.
When raw water is subjected to membrane filtration, a substance having a size exceeding the pore size of the membrane (for example, a suspended substance in raw water) is blocked by the filter used for filtration, and concentration polarization may occur, or cake may be generated. is there. These become pollutants of the filter, block the pores of the filter, increase the filtration resistance, increase the transmembrane pressure difference, and reduce the filtration flow rate (water permeation rate). The filter whose transmembrane pressure has risen to a predetermined value is reused after removing contaminants by washing and returning the filtration flow rate to the original value.
　このようなフィルターを洗浄するための洗浄液として、過酸化水素を含有する洗浄液が知られている。例えば、特許文献１は、ヒドロキシジカルボン酸と、過酸化水素と、重金属化合物とを含む分離膜用洗浄剤を提案している。 A cleaning solution containing hydrogen peroxide is known as a cleaning solution for cleaning such filters. For example, Patent Document 1 proposes a cleaning agent for a separation membrane containing hydroxydicarboxylic acid, hydrogen peroxide, and a heavy metal compound.
国際公開第２００８／１２０５０９号International Publication No. 2008/120509
　原水の精製に用いるフィルターを洗浄するために、例えば特許文献１が提案するような、過酸化水素を含有する洗浄液を好適に使用することができる。
　従来技術におけるフィルターの洗浄は、例えば、フィルターの透水量が所定値まで減少したとき、フィルターの膜間差圧が所定値まで上昇したとき等、又は定期的に、一定濃度の洗浄液を用いて一定時間行われることが通常であった。 In order to wash the filter used for purifying the raw water, for example, a washing liquid containing hydrogen peroxide as proposed in Patent Document 1 can be preferably used.
The cleaning of the filter in the prior art is performed, for example, when the water permeation amount of the filter is reduced to a predetermined value, when the transmembrane pressure difference of the filter is increased to a predetermined value, or periodically, using a cleaning solution having a constant concentration. It was usually done on time.
　このような定型的な条件下の洗浄によると、
　　洗浄液濃度若しくは洗浄時間、又はこれらの双方が、フィルターの汚染の程度に対して過小となり、所期の洗浄効果が得られない場合があり、或いは、
　　洗浄液濃度若しくは洗浄時間、又はこれらの双方が、フィルターの汚染の程度に対して過大となり、所期の洗浄効果は得られるものの、洗浄液及び洗浄時間が無駄に消費される場合がある。 According to washing under such routine conditions,
The concentration of the cleaning solution, the cleaning time, or both may be too small for the degree of contamination of the filter, and the desired cleaning effect may not be obtained, or
The concentration of the cleaning liquid, the cleaning time, or both of them become excessive with respect to the degree of contamination of the filter, and although the desired cleaning effect is obtained, the cleaning liquid and the cleaning time may be wasted.
　本発明は、従来技術におけるフィルターの洗浄条件の決定についての上記の問題点を解決するためになされた。
　本発明の目的は、最小量の洗浄液及び最短の洗浄時間によって最大の洗浄効果を得るための、フィルター洗浄条件の決定方法を提供することである。 The present invention has been made to solve the above-mentioned problems regarding the determination of the cleaning conditions for filters in the prior art.
An object of the present invention is to provide a method for determining filter washing conditions for obtaining the maximum washing effect with the minimum washing liquid and the shortest washing time.
　上記の目的を達成する本発明は、以下のとおりのものである。
　《態様１》原水の精製に用いられるフィルターを、過酸化水素を含有する洗浄液で洗浄するための、フィルター洗浄条件の決定方法であって、
　洗浄液中の過酸化水素濃度をＣ、洗浄時間をＴ、前記フィルターの洗浄前の透水量をＰ１、及び洗浄後の透水量をＰ２としたときに、
　　差（Ｐ２－Ｐ１）値から積ＣＴ値を推定するステップ、及び
　　積ＣＴ値から差（Ｐ２－Ｐ１）値を推定するステップ
のうちのいずれかの推定ステップを含む、フィルター洗浄条件の決定方法。
　《態様２》前記原水が、海水、河川水、湖沼水、地下水、下水、又は工業排水である、態様１に記載のフィルター洗浄条件の決定方法。
　《態様３》前記推定ステップが、
　積ＣＴ値と差（Ｐ２－Ｐ１）値との関係式を用いて行われる、態様１又は２に記載のフィルター洗浄条件の決定方法。
　《態様４》前記関係式が、積ＣＴ値及び差（Ｐ２－Ｐ１）値のうちの、いずれかを説明変数とし、他方を目的変数とする最尤推定によって得られた回帰式である、態様３に記載のフィルター洗浄条件の決定方法。
　《態様５》前記説明変数が複数の領域に分割されており、前記説明変数の領域ごとに回帰式がそれぞれ設定される、態様４に記載のフィルター洗浄条件の決定方法。
　《態様６》前記推定ステップが、差（Ｐ２－Ｐ１）値から積ＣＴ値を推定するステップであり、
　推定された積ＣＴ値に基づいて、所定の過酸化水素濃度Ｃから洗浄時間Ｔが決定される、態様１～５のいずれか一項に記載のフィルター洗浄条件の決定方法。
　《態様７》前記推定ステップが、差（Ｐ２－Ｐ１）値から積ＣＴ値を推定するステップであり、
　推定された積ＣＴ値に基づいて、所定の洗浄時間Ｔから過酸化水素濃度Ｃが決定される、態様１～５のいずれか一項に記載のフィルター洗浄条件の決定方法。
　《態様８》前記推定ステップが、積ＣＴ値から差（Ｐ２－Ｐ１）値を推定するステップであり、
　推定された差（Ｐ２－Ｐ１）値に基づいて、所定の洗浄後の透水量Ｐ２から洗浄前の透水量Ｐ１が決定される、態様１～５のいずれか一項に記載のフィルター洗浄条件の決定方法。
　《態様９》前記推定ステップが、積ＣＴ値から差（Ｐ２－Ｐ１）値を推定するステップであり、
　推定された差（Ｐ２－Ｐ１）値に基づいて、検知された透水量Ｐ１値から洗浄後の透水量Ｐ２が決定される、態様１～５のいずれか一項に記載のフィルター洗浄条件の決定方法。
　《態様１０》前記原水の精製に用いられるフィルターが、精密ろ過膜、限外ろ過膜、ナノろ過膜、又は逆浸透膜である、態様１～９のいずれか一項に記載のフィルター洗浄条件の決定方法。
　《態様１１》前記洗浄液が、過酸化水素水、又は過酸化水素及び鉄化合物を含有する洗浄液である、態様１～１０のいずれか一項に記載のフィルター洗浄条件の決定方法。
　《態様１２》前記過酸化水素及び鉄化合物を含む洗浄液が、ヒドロキシジカルボン酸を更に含有する、態様１１に記載のフィルター洗浄条件の決定方法。
　《態様１３》前記原水が、海水又は河川水である、態様１～１２のいずれか一項に記載のフィルター洗浄条件の決定方法。 The present invention that achieves the above object is as follows.
<Aspect 1> A method for determining filter washing conditions for washing a filter used for purification of raw water with a washing liquid containing hydrogen peroxide,
When the hydrogen peroxide concentration in the cleaning liquid is C, the cleaning time is T, the water permeability of the filter before cleaning is P1, and the water permeability after cleaning is P2,
A method for determining filter cleaning conditions, comprising: an estimation step of a product CT value from a difference (P2-P1) value; and an estimation step of estimating a difference (P2-P1) value from the product CT value.
<<Aspect 2>> The method for determining filter washing conditions according to aspect 1, wherein the raw water is seawater, river water, lake water, groundwater, sewage, or industrial wastewater.
<<Aspect 3>>
The method for determining filter washing conditions according to aspect 1 or 2, which is performed using a relational expression between a product CT value and a difference (P2-P1) value.
<<Aspect 4>> The aspect is a regression equation obtained by maximum likelihood estimation in which one of the product CT value and the difference (P2-P1) value is an explanatory variable and the other is an objective variable. The method for determining filter washing conditions according to item 3.
<Aspect 5> The method for determining filter washing conditions according to Aspect 4, wherein the explanatory variable is divided into a plurality of regions, and a regression equation is set for each region of the explanatory variable.
<<Aspect 6>> The estimating step is a step of estimating a product CT value from a difference (P2-P1) value,
The method for determining filter cleaning conditions according to any one of aspects 1 to 5, wherein the cleaning time T is determined from a predetermined hydrogen peroxide concentration C based on the estimated product CT value.
<<Aspect 7>> The estimating step is a step of estimating a product CT value from the difference (P2-P1) value,
The method for determining filter cleaning conditions according to any one of aspects 1 to 5, wherein the hydrogen peroxide concentration C is determined from a predetermined cleaning time T based on the estimated product CT value.
<<Aspect 8>> The estimating step is a step of estimating a difference (P2-P1) value from the product CT value,
The filter washing conditions according to any one of aspects 1 to 5, wherein the water permeability P1 before washing is determined from the water permeability P2 after a predetermined washing based on the estimated difference (P2-P1) value. How to decide.
<<Aspect 9>> The estimating step is a step of estimating a difference (P2-P1) value from the product CT value,
Determination of the filter cleaning conditions according to any one of aspects 1 to 5, wherein the permeation rate P2 after cleaning is determined from the detected permeation rate P1 value based on the estimated difference (P2-P1) value. Method.
<Aspect 10> The filter washing conditions according to any one of Aspects 1 to 9, wherein the filter used for purifying the raw water is a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, or a reverse osmosis membrane. How to decide.
<Aspect 11> The method for determining filter washing conditions according to any one of Aspects 1 to 10, wherein the cleaning liquid is a hydrogen peroxide solution or a cleaning liquid containing hydrogen peroxide and an iron compound.
<Aspect 12> The method for determining filter washing conditions according to Aspect 11, wherein the cleaning liquid containing hydrogen peroxide and an iron compound further contains hydroxydicarboxylic acid.
<<Aspect 13>> The method for determining filter washing conditions according to any one of Aspects 1 to 12, wherein the raw water is seawater or river water.
　本発明によると、最小量の洗浄液及び最短の洗浄時間によって最大の洗浄効果を得るための、フィルター洗浄条件の決定方法が提供される。 According to the present invention, there is provided a method of determining filter cleaning conditions for obtaining the maximum cleaning effect with the minimum cleaning liquid and the shortest cleaning time.
図１は、本発明を好適に適用できる原水精製装置の構成の一例を示す模式図である。FIG. 1 is a schematic diagram showing an example of the configuration of a raw water purification apparatus to which the present invention can be suitably applied. 図２は、本発明を好適に適用できる原水精製装置の一態様である、海水淡水化装置の構成の一例を示す模式図である。FIG. 2 is a schematic diagram showing an example of the configuration of a seawater desalination apparatus, which is an aspect of a raw water purification apparatus to which the present invention can be suitably applied. 図３は、実験例１で得られた、差（Ｐ２－Ｐ１）と積ＣＴ値との関係を示すグラフである。FIG. 3 is a graph showing the relationship between the difference (P2-P1) and the product CT value obtained in Experimental Example 1. 図４は、実験例２で得られた、差（Ｐ２－Ｐ１）と積ＣＴ値との関係を示すグラフである。FIG. 4 is a graph showing the relationship between the difference (P2-P1) and the product CT value obtained in Experimental Example 2. 図５は、実験例３で得られた、差（Ｐ２－Ｐ１）と積ＣＴ値との関係を示すグラフである。FIG. 5 is a graph showing the relationship between the difference (P2-P1) and the product CT value obtained in Experimental Example 3. 図６は、実験例４で得られた、差（Ｐ２－Ｐ１）と積Ｃ’Ｔ値との関係を示すグラフである。FIG. 6 is a graph showing the relationship between the difference (P2-P1) and the product C'T value obtained in Experimental Example 4.
　本発明のフィルター洗浄条件の決定方法は、
　原水の精製に用いられるフィルターを、過酸化水素を含有する洗浄液で洗浄するための、フィルター洗浄条件の決定方法であって、
　洗浄液中の過酸化水素濃度をＣ、洗浄時間をＴ、前記フィルターの洗浄前の透水量をＰ１、及び洗浄後の透水量をＰ２としたときに、
　　差（Ｐ２－Ｐ１）値から積ＣＴ値を推定するステップ、及び
　　積ＣＴ値から差（Ｐ２－Ｐ１）値を推定するステップ
のうちのいずれかの推定ステップを含む。 The method for determining the filter washing conditions of the present invention is
A method for determining filter cleaning conditions, for cleaning a filter used for purification of raw water with a cleaning solution containing hydrogen peroxide,
When the hydrogen peroxide concentration in the cleaning liquid is C, the cleaning time is T, the water permeability of the filter before cleaning is P1, and the water permeability after cleaning is P2,
The method includes any one of the step of estimating a product CT value from the difference (P2-P1) value and the step of estimating a difference (P2-P1) value from the product CT value.
《原水》
　本発明のフィルター洗浄条件の決定方法は、原水の精製に用いられるフィルターを洗浄する際に、好適に適用される。
　原水としては、例えば、海水、河川水、湖沼水、地下水、下水、工業排水等が挙げられる。
　海水の精製は、例えば、海水から不純物を除去して魚介類飼育用の海水を製造すること、海水を淡水化すること等を含む。河川水、湖沼水、地下水、下水、及び工業排水の精製は、例えば、これらの原水から不純物を除去して飲料水を製造すること等を含む。
　フィルターについては、後述する。 《Raw water》
The method for determining filter washing conditions of the present invention is preferably applied when washing a filter used for purifying raw water.
Examples of raw water include seawater, river water, lake water, groundwater, sewage, and industrial wastewater.
Purification of seawater includes, for example, removing impurities from seawater to produce seawater for breeding seafood, desalinating seawater, and the like. Purification of river water, lake water, groundwater, sewage, and industrial wastewater includes, for example, removing impurities from these raw water to produce drinking water.
The filter will be described later.
　本発明者らは、本発明の目的を達成するために、洗浄液の種類及び濃度と、洗浄時間と、洗浄前後のフィルターの透水量との間に、法則的な関係が見出せないか否かについて、詳細な検討を行った。その結果、洗浄液として過酸化水素を含有する洗浄液を用いたときに、フィルターの洗浄後の透水量Ｐ２及び洗浄前の透水量Ｐ１の差（Ｐ２－Ｐ１）と、洗浄液中の過酸化水素濃度Ｃ及び洗浄時間Ｔの積ＣＴとの間に、高度の相関関係が存在することが分かった。
　すなわち、過酸化水素を含有する洗浄液を用いたときには、例えば横軸に差（Ｐ２－Ｐ１）をとり、縦軸に積ＣＴをとってプロットしたグラフが、高い相関で１本の直線又は曲線に乗るのである。 In order to achieve the object of the present invention, the present inventors have examined whether or not a legal relationship can be found between the type and concentration of the cleaning liquid, the cleaning time, and the water permeation amount of the filter before and after cleaning. , Detailed examination was done. As a result, when a cleaning liquid containing hydrogen peroxide was used as the cleaning liquid, the difference between the water permeation amount P2 after cleaning the filter and the water permeation amount P1 before cleaning (P2-P1) and the hydrogen peroxide concentration C in the cleaning liquid It has been found that there is a high degree of correlation between the product and the product CT of the cleaning time T.
That is, when a cleaning solution containing hydrogen peroxide is used, for example, a graph plotting the difference (P2-P1) on the horizontal axis and the product CT on the vertical axis is a single line or curve with a high correlation. Get on.
　そしてこの相関関係は、フィルターの洗浄前の透水量Ｐ１及び洗浄後の透水量Ｐ２それぞれの値によらず、両者の差（Ｐ２－Ｐ１）によって規定されることが分かった。
　つまり、新品時のフィルターの透水量を１００％としたときに、
　　洗浄前の透水量Ｐ１が２０％のフィルターを洗浄して洗浄後の透水量Ｐ２を６０％まで回復する場合（差（Ｐ２－Ｐ１）＝６０％－２０％＝４０％ｐｔ）と、
　　洗浄前の透水量Ｐ１が４０％のフィルターを洗浄して洗浄後の透水量Ｐ２を８０％まで回復する場合（差（Ｐ２－Ｐ１）＝８０％－４０％＝４０％ｐｔ）と
では、同じ積ＣＴ値が対応する。 It was found that this correlation is defined by the difference (P2-P1) between the two, regardless of the values of the water permeability P1 before cleaning the filter and the water permeability P2 after cleaning.
In other words, when the water permeability of the new filter is 100%,
When the filter with 20% of water permeability P1 before washing is washed to recover the water permeability P2 after washing to 60% (difference (P2-P1)=60%-20%=40%pt),
Same as when the filter with 40% of water permeability P1 before cleaning is recovered to 80% of water permeability P2 after cleaning (difference (P2-P1)=80%-40%=40%pt) The product CT value corresponds.
　過酸化水素を含有しない洗浄液の場合には、差（Ｐ２－Ｐ１）と積ＣＴとの間に有意の相関は見出されなかった。
　本発明は、このような知見に基づいてなされたものである。
　なお本明細書において、「％ｐｔ」（パーセントポイント）とは、百分率で表された数値同士の差を表す単位である。
　以下、本発明について、詳細に詳説する。 No significant correlation was found between the difference (P2-P1) and the product CT in the case of the washing solution containing no hydrogen peroxide.
The present invention has been made based on such findings.
In the present specification, “%pt” (percentage point) is a unit representing a difference between numerical values expressed in percentage.
Hereinafter, the present invention will be described in detail.
《推定ステップ》
　洗浄液中の過酸化水素濃度をＣ、洗浄時間をＴ、前記フィルターの洗浄前の透水量をＰ１、及び洗浄後の透水量をＰ２としたときに、
　　差（Ｐ２－Ｐ１）値から積ＣＴ値を推定するステップ、及び
　　積ＣＴ値から差（Ｐ２－Ｐ１）値を推定するステップ
のうちのいずれかの推定ステップを含む。 《Estimation step》
When the hydrogen peroxide concentration in the cleaning liquid is C, the cleaning time is T, the water permeability of the filter before cleaning is P1, and the water permeability after cleaning is P2,
The method includes any one of the step of estimating a product CT value from the difference (P2-P1) value and the step of estimating a difference (P2-P1) value from the product CT value.
〈関係式〉
　本発明における推定ステップは、
　　洗浄液中の過酸化水素濃度Ｃ及び洗浄時間Ｔの積ＣＴ値と、
　　洗浄後のフィルターの透水量Ｐ２及び洗浄前のフィルターの透水量Ｐ１の差（Ｐ２－Ｐ１）値と
の関係式を用いて行われることが好ましい。 <Relational expression>
The estimation step in the present invention is
The product CT value of the hydrogen peroxide concentration C in the cleaning liquid and the cleaning time T,
It is preferable to use a relational expression between the difference (P2-P1) between the water permeability P2 of the filter after washing and the water permeability P1 of the filter before washing.
　推定ステップに用いられる関係式は、例えば、積ＣＴ値及び差（Ｐ２－Ｐ１）値のうちの、いずれかを説明変数とし、他方を目的変数とする最尤推定によって得られた回帰式であることが好ましい。積ＣＴ値と差（Ｐ２－Ｐ１）値との関係式として、このような回帰式を用いることにより、精度の高い推定が可能となる点で、好ましい。
　以下、差（Ｐ２－Ｐ１）値を説明変数とし、積ＣＴ値を目的変数とする場合を例として、好ましい回帰式について説明するが、積ＣＴ値を説明変数とし、差（Ｐ２－Ｐ１）値を目的変数とする回帰式も同様に開示されていると理解されるべきである。 The relational expression used in the estimation step is, for example, a regression expression obtained by the maximum likelihood estimation in which one of the product CT value and the difference (P2-P1) value is the explanatory variable and the other is the objective variable. It is preferable. By using such a regression equation as the relational expression between the product CT value and the difference (P2-P1) value, it is preferable in that highly accurate estimation is possible.
Hereinafter, a preferred regression equation will be described by taking the case where the difference (P2-P1) value is the explanatory variable and the product CT value is the objective variable, but the product CT value is the explanatory variable and the difference (P2-P1) value is It should be understood that a regression equation with the objective variable as is also disclosed.
　本発明における関係式は、例えば、差（Ｐ２－Ｐ１）値を説明変数とし、積ＣＴ値を目的変数とする最尤推定によって得られた回帰式であってよく、例えば、下記数式（１）：
　　ＣＴ＝Ａ（Ｐ２－Ｐ１）Ｂ＋Ｃ　　　（１）
｛数式（１）中、Ａ、Ｂ、及びＣは、それぞれ、係数である。｝の形式で表される式であってよい。数式（１）を求めるための最尤推定は、例えば最小二乗法であってよい。最小二乗法において、係数Ａ、Ｂ、及びＣは、目的変数である積ＣＴ値の実測値と、数式（１）によって推定された積ＣＴ値との二乗和誤差が最小となるように決定される。
　この場合の相関係数Ｒ２は、０．８０以上とすることができ、更に、０．８５以上、特に０．９０以上とすることができる。 The relational expression in the present invention may be, for example, a regression expression obtained by maximum likelihood estimation using a difference (P2-P1) value as an explanatory variable and a product CT value as an objective variable. For example, the following mathematical expression (1) :
CT=A(P2-P1) B +C (1)
{In the mathematical expression (1), A, B, and C are coefficients respectively. } May be a formula represented by the form. The maximum likelihood estimation for obtaining the mathematical expression (1) may be the least squares method, for example. In the least squares method, the coefficients A, B, and C are determined so that the sum of squares error between the measured value of the product CT value, which is the objective variable, and the product CT value estimated by Equation (1) becomes the minimum. It
The correlation coefficient R 2 in this case can be 0.80 or more, further 0.85 or more, and particularly 0.90 or more.
　本発明のある実施態様では、過酸化水素、塩化第一鉄、及び酒石酸を含有する洗浄液を用いた場合、差（Ｐ２－Ｐ１）値の単位を％ｐｔ（パーセントポイント）、積ＣＴの単位を質量％・ｈとして、上記数式（１）において、係数Ａが概ね１．０×１０－８以上５．０×１０－８以下、係数Ｂが概ね３．０以上６．０以下、係数Ｃが概ね－０．５以上＋０．５以下であり、相関係数Ｒ２が概ね０．９０以上の高度の相関を示す回帰式が得られた。 In an embodiment of the present invention, when a cleaning solution containing hydrogen peroxide, ferrous chloride, and tartaric acid is used, the unit of difference (P2-P1) value is% pt (percent point), and the unit of product CT is As the mass%·h, in the above formula (1), the coefficient A is approximately 1.0×10 −8 or more and 5.0×10 −8 or less, the coefficient B is approximately 3.0 or more and 6.0 or less, and the coefficient C is A regression equation showing a high correlation of approximately −0.5 or more and +0.5 or less and a correlation coefficient R 2 of approximately 0.90 or more was obtained.
　本発明では、最尤推定を行う説明変数の領域の全範囲にわたって単一の回帰式を設定してもよいし、説明変数を複数の領域に分割し、分割された領域ごとに別個の回帰式を設定してもよい。説明変数を複数の領域に分割し、分割された領域ごとに別個の回帰式を設定すると、より低次の（数式（１）中の係数Ｂの値が１に近い）回帰式によって、より精度の高い推定が可能になる。或いは、説明変数を複数の領域に分割し、分割された領域ごとに関係式を考慮しつつ設定された定数を、目的変数として採用してもよい。 In the present invention, a single regression equation may be set over the entire range of the explanatory variable region for which the maximum likelihood estimation is performed, or the explanatory variable may be divided into a plurality of regions and a separate regression equation may be set for each divided region. May be set. If the explanatory variable is divided into a plurality of areas and a separate regression equation is set for each of the divided areas, a lower-order regression equation (where the value of the coefficient B in equation (1) is close to 1) provides more accuracy. A high estimate of Alternatively, the explanatory variable may be divided into a plurality of areas, and a constant set while considering the relational expression for each of the divided areas may be adopted as the objective variable.
　なお、通常の最尤推定では、変数の推定にあたり、既知の又は予め定められる側の変数を説明変数とし、推定される側の変数を目的変数として導出された回帰式を用いるのが通常である。しかしながら本発明では、両変数間の相関が極めて高いため、推定される側の変数を説明変数とし、既知の又は予め定められる側の変数を目的変数として導出された回帰式を用いて推定を行っても、精度の高い推定値が得られる。
　したがって例えば、上記数式（１）で表される回帰式を用いて、既知の積ＣＴ値からの差（Ｐ２－Ｐ１）値の推定を行ってもよい。 In the normal maximum likelihood estimation, in estimating variables, it is usual to use a regression equation derived by using known or predetermined variables as explanatory variables, and estimated variables as objective variables. .. However, in the present invention, since the correlation between the two variables is extremely high, the estimated variable is used as an explanatory variable, and the estimation is performed using a regression formula derived by using a known or predetermined variable as the objective variable. However, a highly accurate estimated value can be obtained.
Therefore, for example, the regression (Equation (1)) may be used to estimate the difference (P2-P1) value from the known product CT value.
　積ＣＴ値と差（Ｐ２－Ｐ１）値との関係式は、定期的に、又は有意量の新規データが蓄積したタイミングで、新規データを加味して更新されることが好ましい。 The relational expression between the product CT value and the difference (P2-P1) value is preferably updated periodically or at the timing when a significant amount of new data is accumulated, taking into account the new data.
〈積ＣＴ値〉
　積ＣＴ値は、過酸化水素濃度Ｃ（質量％）と、洗浄時間Ｔ（ｈ）との積である。
　積ＣＴ値と差（Ｐ２－Ｐ１）値との関係式としての回帰式を求めるための最尤推定、及び推定ステップにおける積ＣＴ値の範囲は、実際的な洗浄条件の範囲内とすることが、推定の精度を高くすることができる点で好ましい。積ＣＴ値の範囲としては、１０質量％・ｈ以下が好ましく、０．１質量％・ｈ以上８質量％・ｈ以下がより好ましく、更に好ましくは０．５質量％・ｈ以上６質量％・ｈ以下である。 <Product CT value>
The product CT value is the product of the hydrogen peroxide concentration C (mass %) and the cleaning time T(h).
The maximum likelihood estimation for obtaining the regression equation as the relational expression between the product CT value and the difference (P2-P1) value, and the range of the product CT value in the estimation step may be within the range of practical cleaning conditions. It is preferable in that the accuracy of estimation can be increased. The product CT value range is preferably 10% by mass or less, more preferably 0.1% by mass or more and 8% by mass or less, and even more preferably 0.5% by mass or more and 6% by mass or more. It is less than or equal to h.
〈差（Ｐ２－Ｐ１）値〉
　差（Ｐ２－Ｐ１）値は、フィルター新品時の透水量を１００％としたときに、洗浄後の透水量Ｐ２（％）から洗浄前の透水量Ｐ１（％）を減じた値であり、その単位としては、百分率で表された数値同士の差を表す単位である％ｐｔ（パーセントポイント）を用いる。
　洗浄前後の透水量Ｐ１及びＰ２は、それぞれ、透水量として測定又は推定された値であってもよいし、膜間差圧等の他の指標からの換算値であってもよい。 <Difference (P2-P1) value>
The difference (P2-P1) value is the value obtained by subtracting the water permeability P1 (%) before washing from the water permeability P2 (%) after washing when the water permeability of a new filter is 100%. As a unit,% pt (percent point), which is a unit showing a difference between numerical values expressed in percentage, is used.
The water permeation rates P1 and P2 before and after the cleaning may each be a value measured or estimated as the water permeation rate, or a converted value from another index such as the transmembrane pressure difference.
　積ＣＴ値と差（Ｐ２－Ｐ１）値との関係式としての回帰式を求めるための最尤推定、及び推定ステップにおける差（Ｐ２－Ｐ１）値の範囲は、実際的な洗浄条件の範囲内とすることが、推定の精度を高くすることができる点で好ましい。差（Ｐ２－Ｐ１）値の範囲としては、１０％ｐｔ以上８０％ｐｔ以下が好ましく、より好ましくは２０％ｐｔ以上７０％ｐｔ以下であり、更に好ましくは３０％ｐｔ以上６０％ｐｔ以下である。 The maximum likelihood estimation for obtaining the regression equation as the relational expression between the product CT value and the difference (P2-P1) value, and the range of the difference (P2-P1) value in the estimation step are within the range of practical cleaning conditions. Is preferable in that the accuracy of estimation can be increased. The range of the difference (P2-P1) value is preferably 10% pt or more and 80% pt or less, more preferably 20% pt or more and 70% pt or less, and further preferably 30% pt or more and 60% pt or less. ..
　本発明では、フィルターの汚れの程度が著しく、フィルター付着物の量が過度に多くなった場合には、推定ステップにおける推定の精度が損なわれる場合がある。これを避けるため、フィルター洗浄前の透水量Ｐ１の値は、１０％以上であることが好ましく、より好ましくは１５％以上、更に好ましくは２０％以上である。
　フィルター洗浄後の透水量Ｐ２については、必要以上に高い透水量を求めると、洗浄液及び洗浄時間の消費が無為に多くなって、洗浄効率が損なわれることが懸念される。これを避けるため、フィルター洗浄後の透水量Ｐ２の値は、１００％未満であってよく、好ましくは９５％以下であり、より好ましくは９０％以下であり、さらに好ましくは８５％以下である。 In the present invention, when the degree of contamination of the filter is significant and the amount of the filter deposits becomes excessively large, the estimation accuracy in the estimation step may be impaired. In order to avoid this, the value of the water permeation amount P1 before washing the filter is preferably 10% or more, more preferably 15% or more, still more preferably 20% or more.
Regarding the water permeation rate P2 after filter cleaning, if an unnecessarily high water permeation rate is required, it is feared that the consumption of the cleaning liquid and the cleaning time will be unnecessarily increased and the cleaning efficiency will be impaired. In order to avoid this, the value of the water permeation amount P2 after filter washing may be less than 100%, preferably 95% or less, more preferably 90% or less, and further preferably 85% or less.
〈推定ステップの態様〉
　本発明のフィルター洗浄条件の決定方法は、
　　差（Ｐ２－Ｐ１）値から積ＣＴ値を推定するステップ（第１の推定ステップ）、及び
　　積ＣＴ値から差（Ｐ２－Ｐ１）値を推定するステップ（第２の推定ステップ）
のうちのいずれかの推定ステップを含む。 <Aspect of estimation step>
The method for determining the filter washing conditions of the present invention is
Estimating the product CT value from the difference (P2-P1) value (first estimation step), and estimating the difference (P2-P1) value from the product CT value (second estimation step)
And an estimation step of any one of the above.
（第１の推定ステップ）
　第１の推定ステップでは、差（Ｐ２－Ｐ１）値から積ＣＴ値を推定する。この場合、差（Ｐ２－Ｐ１）値は、例えば、検知されたフィルター洗浄前の透水量Ｐ１の値と、所望の洗浄後の透水量Ｐ２の値とに基づいて設定されてよい。
　検知されたフィルター洗浄前の透水量Ｐ１とは、透水量として直接測定された値であってもよく、膜間差圧等の他の測定値から換算された値であってもよく、時間の経過等から経験的に推定された値であってもよい。
　フィルター洗浄後の透水量Ｐ２は、推定精度の観点からの差（Ｐ２－Ｐ１）値の推奨範囲、洗浄効率の観点からのＰ２値の推奨範囲等を考慮したうえで、適宜に設定されてよい。 (First estimation step)
In the first estimation step, the product CT value is estimated from the difference (P2-P1) value. In this case, the difference (P2-P1) value may be set, for example, based on the detected value of the water permeation amount P1 before filter cleaning and the desired value of the water permeation amount P2 after cleaning.
The detected water permeation amount P1 before filter cleaning may be a value directly measured as the water permeation amount, or a value converted from other measured values such as transmembrane pressure difference, It may be a value empirically estimated from the progress and the like.
The water permeability P2 after filter cleaning may be appropriately set in consideration of the recommended range of the difference (P2-P1) value from the viewpoint of estimation accuracy, the recommended range of the P2 value from the viewpoint of cleaning efficiency, and the like. ..
　第１の推定ステップにて推定された積ＣＴ値に基づいて、フィルターの洗浄条件を決定することができる。
　例えば、所定の過酸化水素濃度Ｃから洗浄時間Ｔが決定されてよい。洗浄されるフィルターの材質によっては、フィルターの腐食防止のために、洗浄液中の過酸化水素濃度Ｃを所定の値以下に制限する必要が生じる場合がある。このようなとき、推定された積ＣＴ値に基づいて、所定の過酸化水素濃度Ｃから決定された洗浄時間Ｔを採用することにより、フィルターを腐食させずに所望の洗浄後透水量Ｐ２を実現することができる。
　或いは、所定の洗浄時間Ｔから過酸化水素濃度Ｃが決定されてよい。例えば、原水精製設備の運転スケジュール等によって、洗浄時間Ｔを所定の時間内に終了するような制限が課される場合がある。このようなとき、推定された積ＣＴ値に基づいて、所定の洗浄時間Ｔから決定された過酸化水素濃度Ｃを採用することにより、所定の制限時間で所望の洗浄後透水量Ｐ２を実現することができる。 The cleaning condition of the filter can be determined based on the product CT value estimated in the first estimation step.
For example, the cleaning time T may be determined from the predetermined hydrogen peroxide concentration C. Depending on the material of the filter to be cleaned, it may be necessary to limit the hydrogen peroxide concentration C in the cleaning liquid to a predetermined value or less in order to prevent the filter from being corroded. In such a case, by adopting the cleaning time T determined from the predetermined hydrogen peroxide concentration C based on the estimated product CT value, the desired post-cleansing water permeation amount P2 is realized without corroding the filter. can do.
Alternatively, the hydrogen peroxide concentration C may be determined from the predetermined cleaning time T. For example, there is a case where a limitation is imposed such that the cleaning time T is completed within a predetermined time depending on the operation schedule of the raw water purification facility. In such a case, the hydrogen peroxide concentration C determined from the predetermined cleaning time T is adopted based on the estimated product CT value to realize a desired post-cleansing water permeation amount P2 within a predetermined time limit. be able to.
（第２の推定ステップ）
　第２の推定ステップでは、積ＣＴ値から差（Ｐ２－Ｐ１）値を推定する。この場合、積ＣＴ値は、例えば、フィルターの腐食防止、取り扱いの安全性等、及び洗浄効率を考慮して設定された過酸化水素濃度Ｃと、原水精製設備の運転スケジュール等を考慮して設定された洗浄時間Ｔとの積であってよい。 (Second estimation step)
In the second estimation step, the difference (P2-P1) value is estimated from the product CT value. In this case, the product CT value is set in consideration of, for example, the hydrogen peroxide concentration C set in consideration of filter corrosion prevention, handling safety, and cleaning efficiency, and the operation schedule of the raw water purification equipment. It may be a product of the cleaning time T and the cleaning time T.
　第２の推定ステップにて推定された差（Ｐ２－Ｐ１）値に基づいて、フィルターの洗浄条件等を決定することができる。
　例えば、フィルター洗浄後の所望の透水量Ｐ２から、洗浄前の透水量Ｐ１が決定されてよい。この態様では、例えば、所定条件のフィルター洗浄によって、所望の洗浄後透水量Ｐ２を実現するためには、洗浄前透水量Ｐ１がどのくらいまで低下したときに洗浄を行えばよいかについての指針を得ることができる。
　或いは、フィルター洗浄前の透水量Ｐ１から洗浄後の所望の透水量Ｐ２が決定（推定）されてよい。この態様では、例えば、既知の透水量Ｐ１のフィルターを、所定の過酸化水素濃度Ｃ及び所定の洗浄時間Ｔにて洗浄したときに得らえる洗浄後透水量Ｐ２の値を、事前に高い精度で知ることが可能となる。この場合、例えば、洗浄終了後の原水精製運転再開時の運転条件を、得られたＰ２値に基づいて適切に設定することができるから、運転再開時の不安定期間を最短にすることが可能となる。 Based on the difference (P2-P1) value estimated in the second estimation step, the filter cleaning condition and the like can be determined.
For example, the permeation rate P1 before cleaning may be determined from the desired permeation rate P2 after filter cleaning. In this aspect, for example, in order to achieve the desired post-washing water permeation amount P2 by the filter washing under the predetermined conditions, a guideline as to how much the pre-washing water permeation amount P1 should be lowered to perform the washing is obtained. be able to.
Alternatively, a desired water permeation rate P2 after cleaning may be determined (estimated) from the water permeation rate P1 before filter cleaning. In this aspect, for example, the value of the post-cleaning water permeability P2 obtained when the filter having the known water permeability P1 is cleaned at the predetermined hydrogen peroxide concentration C and the predetermined cleaning time T is highly accurate in advance. It becomes possible to know in. In this case, for example, the operating conditions when restarting the raw water purification operation after the end of washing can be appropriately set based on the obtained P2 value, so that the unstable period when restarting the operation can be minimized. Becomes
《洗浄液》
　本発明で用いられる洗浄液は、過酸化水素を含有する。
　本発明で用いられる洗浄液は、過酸化水素溶液（好ましくは過酸化水素水）であってもよいし、過酸化水素及び鉄化合物を含有する洗浄液であってもよい。この過酸化水素及び鉄化合物を含む洗浄液は、ヒドロキシジカルボン酸を更に含有していてもよい。洗浄液は、任意成分として、例えば、界面活性剤、キレート剤、ｐＨ調整剤、増粘剤、消泡剤、防腐剤等から選択される１種以上を更に含有していてもよい。 《Cleaning liquid》
The cleaning liquid used in the present invention contains hydrogen peroxide.
The cleaning liquid used in the present invention may be a hydrogen peroxide solution (preferably hydrogen peroxide solution) or a cleaning liquid containing hydrogen peroxide and an iron compound. The cleaning liquid containing the hydrogen peroxide and the iron compound may further contain hydroxydicarboxylic acid. The cleaning liquid may further contain, as an optional component, one or more kinds selected from, for example, a surfactant, a chelating agent, a pH adjusting agent, a thickener, an antifoaming agent and a preservative.
〈過酸化水素〉
　洗浄液中の過酸化水素の濃度は、１ｍｍｏｌ／Ｌ（０．００３４質量％）以上１０，０００ｍｍｏｌ／Ｌ（１０ｍｏｌ／Ｌ、３０質量％）以下の範囲とすることが好ましい。過酸化水素の濃度が１ｍｍｏｌ／Ｌ未満では、フィルターの付着物の除去が完了する前に過酸化水素が消費されてしまい、洗浄効果が不十分となる場合がある。過酸化水素の濃度が１０，０００ｍｍｏｌ／Ｌを超えても、洗浄効果の観点からの問題はない。しかし、高濃度の過酸化水素を用いると、洗浄されるフィルターが腐食する場合がある他、洗浄後の洗浄液排水に大量の過酸化水素が残存するため、多量の還元剤による排水処理が必要となる場合がある。
　洗浄液中の過酸化水素の濃度は、５ｍｍｏｌ／Ｌ（０．０１７質量％）以上５，０００ｍｍｏｌ／Ｌ（５ｍｏｌ／Ｌ、１６質量％）以下の範囲とすることがより好ましく、１０ｍｍｏｌ／Ｌ（０．０３４質量％）以上３，０００ｍｍｏｌ／Ｌ（３ｍｏｌ／Ｌ、１０質量％）以下とすることが更に好ましい。 <hydrogen peroxide>
The concentration of hydrogen peroxide in the cleaning liquid is preferably in the range of 1 mmol/L (0.0034% by mass) or more and 10,000 mmol/L (10 mol/L, 30% by mass) or less. If the concentration of hydrogen peroxide is less than 1 mmol/L, hydrogen peroxide may be consumed before the removal of deposits on the filter is completed, and the cleaning effect may be insufficient. Even if the concentration of hydrogen peroxide exceeds 10,000 mmol/L, there is no problem from the viewpoint of cleaning effect. However, if high-concentration hydrogen peroxide is used, the filter to be cleaned may be corroded, and a large amount of hydrogen peroxide remains in the cleaning liquid wastewater after cleaning, so wastewater treatment with a large amount of reducing agent is required. May be.
The concentration of hydrogen peroxide in the cleaning liquid is more preferably in the range of 5 mmol/L (0.017 mass%) or more and 5,000 mmol/L (5 mol/L, 16 mass%) or less, and 10 mmol/L(0 More preferably, it is 0.034 mass% or more and 3,000 mmol/L (3 mol/L, 10 mass%) or less.
　洗浄液を調製する際、過酸化水素は、過酸化水素の形態で配合されてもよいし、配合後に溶液中で過酸化水素を発生する化合物として配合されてもよい。溶液中で過酸化水素を発生する化合物としては、例えば、過炭酸ナトリウム、過ホウ酸ナトリウム等を挙げることができる。 When preparing the cleaning liquid, hydrogen peroxide may be blended in the form of hydrogen peroxide, or may be blended as a compound that generates hydrogen peroxide in the solution after blending. Examples of the compound that generates hydrogen peroxide in the solution include sodium percarbonate and sodium perborate.
〈鉄化合物〉
　本発明に用いられる洗浄液は、過酸化水素とともに、鉄化合物を更に含有していてもよい。過酸化水素及び鉄化合物を含有する洗浄液は、フェントン反応によってフィルターを効率的に洗浄することができる。
　鉄化合物は、水溶性の鉄塩であってよく、鉄（ＩＩ）イオン及び鉄（ＩＩＩ）イオンのうちの少なくとも１種を含む塩であることが好ましく、より好ましくは、鉄（ＩＩ）イオン又は鉄（ＩＩＩ）イオンを含む塩化物、硫酸塩、硝酸塩等であり、特に、塩化第一鉄及び塩化第二鉄から選択される１種以上を使用することが好ましい。塩化第一鉄及び塩化第二鉄は、いずれも、安価であるうえ、使用後の洗浄液にアルカリ（例えば水酸化ナトリウム）を加えると沈殿して、ろ過によって容易に除去できる点でも好ましい。
　鉄化合物として鉄塩を使用する場合、無水塩であっても含水塩であってもよい。 <Iron compound>
The cleaning liquid used in the present invention may further contain an iron compound in addition to hydrogen peroxide. The cleaning liquid containing hydrogen peroxide and the iron compound can efficiently clean the filter by the Fenton reaction.
The iron compound may be a water-soluble iron salt, and is preferably a salt containing at least one of iron (II) ion and iron (III) ion, more preferably iron (II) ion or It is a chloride containing an iron (III) ion, a sulfate, a nitrate, and the like, and it is particularly preferable to use one or more selected from ferrous chloride and ferric chloride. Ferrous chloride and ferric chloride are both preferable because they are inexpensive and precipitate when an alkali (for example, sodium hydroxide) is added to the cleaning liquid after use and can be easily removed by filtration.
When an iron salt is used as the iron compound, it may be an anhydrous salt or a hydrated salt.
　洗浄液中の鉄化合物の量は、過酸化水素１モルに対して、０．００１モル以上１００モル以下とすることが好ましい。洗浄液中の鉄化合物の量が、過酸化水素１モルに対して０．００１モル未満では、洗浄液に鉄化合物を含有させることの効果が十分に発現されず、フェントン反応が有効に行われない懸念が生ずる。一方で、洗浄液中の鉄化合物の量が過度に多いと、フィルター洗浄後の洗浄液排液の処理に手間及びコストがかかるため、好ましくない。
　洗浄液中の鉄化合物の量は、過酸化水素１モルに対して、０．００５モル以上１０モル以下であることがより好ましく、０．０１モル以上５モル以下であることが更に好ましく、０．０５モル以上１モル以下であることが特に好ましく、とりわけ好ましくは０．１モル以上０．５モル以下である。 The amount of the iron compound in the cleaning liquid is preferably 0.001 mol or more and 100 mol or less with respect to 1 mol of hydrogen peroxide. If the amount of the iron compound in the cleaning liquid is less than 0.001 mol with respect to 1 mol of hydrogen peroxide, the effect of including the iron compound in the cleaning liquid is not sufficiently expressed, and the Fenton reaction may not be effectively performed. Occurs. On the other hand, if the amount of the iron compound in the cleaning liquid is excessively large, it takes time and cost to process the cleaning liquid waste liquid after the filter cleaning, which is not preferable.
The amount of the iron compound in the cleaning liquid is more preferably 0.005 mol or more and 10 mol or less, further preferably 0.01 mol or more and 5 mol or less, and more preferably 0. The amount is particularly preferably 05 mol or more and 1 mol or less, and particularly preferably 0.1 mol or more and 0.5 mol or less.
〈ヒドロキシジカルボン酸〉
　本発明に用いられる洗浄液は、過酸化水素及び鉄化合物とともに、ヒドロキシジカルボン酸を更に含有していてもよい。洗浄液がヒドロキシジカルボン酸を含有することにより、フィルター汚染物質中の無機化合物の除去効率が向上される。
　洗浄液に含まれるヒドロキシジカルボン酸としては、例えば、リンゴ酸、酒石酸、タルトロン酸（別名：２－ヒドロキシマロン酸）、シトラマル酸（別名：２－メチルリンゴ酸）、ジオキシマレイン酸、ジオキシマロン酸等を挙げることができ、これらから選択される１種以上を使用することができる。 <Hydroxydicarboxylic acid>
The cleaning liquid used in the present invention may further contain hydroxydicarboxylic acid together with hydrogen peroxide and an iron compound. The cleaning liquid containing hydroxydicarboxylic acid improves the removal efficiency of the inorganic compounds in the filter contaminants.
Examples of the hydroxydicarboxylic acid contained in the cleaning liquid include malic acid, tartaric acid, tartronic acid (also known as 2-hydroxymalonic acid), citramalic acid (also known as 2-methylmalic acid), dioxymaleic acid and dioxymalonic acid. And one or more selected from these can be used.
　洗浄液中のヒドロキシジカルボン酸の量は、鉄化合物に含まれる鉄原子１モルに対して、０．００１モル以上１０，０００モル以下とすることが好ましい。洗浄液中のヒドロキシジカルボン酸の量が、鉄原子１モルに対して０．００１モル未満では、フィルターの洗浄中に鉄が析出する懸念が生ずる。一方で、洗浄液中のヒドロキシジカルボン酸の量が、鉄原子１モルに対して１０，０００モルを超えると、ヒドロキシジカルボン酸自体が酸化分解される懸念が生じ、フィルター付着物中の有機物の分解除去性能が損なわれる場合がある。
　洗浄液中のヒドロキシジカルボン酸の量は、鉄化合物に含まれる鉄原子１モルに対して、０．００５モル以上１，０００モル以下であることがより好ましく、０．０１０モル以上１００モル以下であることが更に好ましく、０．０１５モル以上５０モル以下であることが特に好ましく、とりわけ好ましくは０．０２０モル以上１０モル以下である。 The amount of hydroxydicarboxylic acid in the cleaning liquid is preferably 0.001 mol or more and 10,000 mol or less with respect to 1 mol of iron atoms contained in the iron compound. If the amount of hydroxydicarboxylic acid in the cleaning liquid is less than 0.001 mol with respect to 1 mol of iron atom, there is a concern that iron will precipitate during cleaning of the filter. On the other hand, if the amount of hydroxydicarboxylic acid in the cleaning liquid exceeds 10,000 mol per 1 mol of iron atom, there is a concern that the hydroxydicarboxylic acid itself may be oxidatively decomposed, and the organic matter in the filter deposit may be decomposed and removed. Performance may be impaired.
The amount of hydroxydicarboxylic acid in the cleaning liquid is more preferably 0.005 mol or more and 1,000 mol or less, and 0.010 mol or more and 100 mol or less, with respect to 1 mol of the iron atom contained in the iron compound. The amount is more preferably 0.015 mol or more and 50 mol or less, and particularly preferably 0.020 mol or more and 10 mol or less.
　本明細書において、鉄原子換算の鉄化合物の濃度とは、鉄化合物のモル濃度に、該鉄化合物の組成式中に含まれる鉄原子の数を乗じた当量濃度を意味する。例えば、１ｍｍｏｌ／Ｌの塩化第一鉄（組成式：ＦｅＣｌ２）の鉄原子換算の濃度は１ｍｍｏｌ／Ｌであり、１ｍｍｏｌ／Ｌの硫酸第二鉄（組成式：Ｆｅ２（ＳＯ４）３）の鉄原子換算の濃度は２ｍｍｏｌ／Ｌである。 In the present specification, the concentration of an iron compound in terms of iron atom means an equivalent concentration obtained by multiplying the molar concentration of the iron compound by the number of iron atoms contained in the composition formula of the iron compound. For example, the concentration of 1 mmol/L ferrous chloride (compositional formula: FeCl 2 ) in terms of iron atoms is 1 mmol/L, and 1 mmol/L ferric sulfate (compositional formula: Fe 2 (SO 4 ) 3 ). The iron atom-equivalent concentration of is 2 mmol/L.
　洗浄液中のヒドロキシジカルボン酸の量は、更に、過酸化水素１モルに対して、０．０００１モル以上１００モル以下であることが好ましい。洗浄液中のヒドロキシジカルボン酸の量が、過酸化水素１モルに対して０．０００１モル未満であると、フィルター付着物中の無機物の洗浄除去効果が不十分となる場合がある。洗浄液中のヒドロキシジカルボン酸の量が、過酸化水素１モルに対して１００モルを超えると、洗浄液のｐＨが過度に低くなり、フェントン反応による洗浄効果が損なわれる場合がある。
　洗浄液中のヒドロキシジカルボン酸の量は、過酸化水素１モルに対して、０．０００５モル以上１０モル以下であることがより好ましく、０．００１モル以上１．０モル以下であることが更に好ましく、０．００３モル以上０．５モル以下であることが特に好ましく、とりわけ好ましくは０．００５モル以上０．１モル以下である。 The amount of hydroxydicarboxylic acid in the cleaning liquid is preferably 0.0001 mol or more and 100 mol or less with respect to 1 mol of hydrogen peroxide. If the amount of hydroxydicarboxylic acid in the cleaning liquid is less than 0.0001 mol with respect to 1 mol of hydrogen peroxide, the effect of cleaning and removing inorganic substances in the filter deposit may be insufficient. When the amount of hydroxydicarboxylic acid in the cleaning liquid is more than 100 mol with respect to 1 mol of hydrogen peroxide, the pH of the cleaning liquid becomes excessively low, which may impair the cleaning effect by the Fenton reaction.
The amount of hydroxydicarboxylic acid in the cleaning liquid is more preferably 0.0005 mol or more and 10 mol or less, and further preferably 0.001 mol or more and 1.0 mol or less, relative to 1 mol of hydrogen peroxide. Is particularly preferably 0.003 mol or more and 0.5 mol or less, and particularly preferably 0.005 mol or more and 0.1 mol or less.
〈界面活性剤〉
　洗浄液が任意的に含有することのできる界面活性剤としては、アニオン性界面活性剤、カチオン性界面活性剤、両性界面活性剤、及びノニオン性界面活性剤のいずれでもよく、これらのうちの１種以上を使用することができる。
　アニオン性界面活性剤としては、例えば、セッケン、高級アルコールの硫酸エステル、アルキルベンゼンスルホン酸、アルキルナフタレンスルホン酸、高級アルコールのリン酸エステル等を；
　カチオン性界面活性剤としては、例えば、第１級アミン塩、第２級アミン塩、第３級アミン塩、第４級アンモニウム塩等を；
　両性界面活性剤としては、例えば、アルキルジメチルアミンオキシド、アルキルジメチルアミノ脂肪酸ベタイン、アルキルカルボキシメチルヒドロキシエチルイミダゾリウムベタイン等を；
　ノニオン性界面活性剤としては、例えば、ポリオキシエチレンアルキルフェニルエーテル、ポリオキシプロピレンアルキルフェニルエーテル、ポリオキシエチレンアルキルエーテル、ポリオキシエチレンアルキルエステル、ポリエチレングリコールアルキルエステル、ポリプロピレングリコールのエチレンオキシド付加物、ポリプロピレングリコールのプロピレンオキシド付加物等を；
それぞれ挙げることができる。 <Surfactant>
The surfactant that the cleaning liquid can optionally contain may be any of anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants, and one of these may be used. The above can be used.
Examples of the anionic surfactant include soap, sulfuric acid ester of higher alcohol, alkylbenzene sulfonic acid, alkylnaphthalene sulfonic acid, phosphoric acid ester of higher alcohol, and the like;
Examples of cationic surfactants include primary amine salts, secondary amine salts, tertiary amine salts, quaternary ammonium salts, and the like;
Examples of the amphoteric surfactant include alkyldimethylamine oxide, alkyldimethylamino fatty acid betaine, alkylcarboxymethyl hydroxyethyl imidazolium betaine, and the like;
Examples of the nonionic surfactant include polyoxyethylene alkylphenyl ether, polyoxypropylene alkylphenyl ether, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyethylene glycol alkyl ester, ethylene oxide adduct of polypropylene glycol, polypropylene glycol. Propylene oxide adduct of
Each can be named.
〈キレート剤〉
　洗浄液が任意的に含有することができるキレート剤としては、例えば、１－ヒドロキシエチリデン－１，１－ジホスホン酸、アミノトリメチレンホスホン酸、エチレンジアミンテトラメチレンホスホン酸、ヘキサメチレンジアミンテトラメチレンホスホン酸、ジエチレントリアミンペンタメチレンホスホン酸等；及びこれらのナトリウム塩、カリウム塩、リチウム塩、アンモニウム塩、アミン塩、アルカノールアミン塩等を挙げることができる。 <Chelating agent>
Examples of the chelating agent that can be optionally contained in the cleaning liquid include 1-hydroxyethylidene-1,1-diphosphonic acid, aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, hexamethylenediaminetetramethylenephosphonic acid and diethylenetriamine. Pentamethylenephosphonic acid and the like; and their sodium salts, potassium salts, lithium salts, ammonium salts, amine salts, alkanolamine salts and the like.
〈洗浄液の溶媒〉
　洗浄液の溶媒は、水、及び水溶性有機溶媒から選択される１種以上を使用することができる。
　水溶性有機溶媒としては、例えば、アルコール、ケトン、エーテル、その他の極性溶媒を挙げることができる。これらの具体例としては、アルコールとして、例えば、メタノール、エタノール、ｎ－プロパノール、ｉ－プロパノール、ｔ－ブタノール、エチレングリコール等を；ケトンとして、例えば、アセトン等を；エーテルとして、例えば、テトラヒドロフラン、１，４－ジオキサン等を；その他の極性溶媒として、例えば、ジメチルホルムアミド等を；それぞれ挙げることができる。
　本発明で用いられる洗浄液として、好ましくは、水、又は水と水溶性有機溶媒との混合溶媒であり、典型的には水である。 <Solvent for cleaning liquid>
As the solvent of the cleaning liquid, one or more selected from water and water-soluble organic solvents can be used.
Examples of water-soluble organic solvents include alcohols, ketones, ethers, and other polar solvents. Specific examples thereof include alcohols such as methanol, ethanol, n-propanol, i-propanol, t-butanol, and ethylene glycol; ketones such as acetone; ethers such as tetrahydrofuran; , 4-dioxane and the like; other polar solvents include, for example, dimethylformamide and the like.
The cleaning liquid used in the present invention is preferably water or a mixed solvent of water and a water-soluble organic solvent, typically water.
〈洗浄液のｐＨ〉
　洗浄液のｐＨは、フィルター汚染物質中の、特に無機物の洗浄除去効果を高く維持するため、酸性領域にあることが好ましい。洗浄薬液のｐＨは、好ましくは６．０以下であり、より好ましくは２．０以上５．０以下であり、更に好ましくは２．０以上４．０以下であり、特に、２．０以上３．０以下であってもよい。 <pH of cleaning solution>
The pH of the cleaning liquid is preferably in an acidic region in order to maintain a high effect of cleaning and removing the inorganic substances in the filter contaminants. The pH of the cleaning chemicals is preferably 6.0 or less, more preferably 2.0 or more and 5.0 or less, further preferably 2.0 or more and 4.0 or less, and particularly 2.0 or more 3 It may be less than or equal to 0.0.
〈洗浄液の適用〉
　本発明では、洗浄液の濃度は、洗浄対象のフィルターの材質等を考慮して予め設定されるか、又は推定されたＣＴ値に応じて適宜設定される。
　設定濃度の洗浄液を都度調製してもよいが、洗浄液中の各成分を所定の比率で含有する濃縮洗浄液（原液）を準備しておき、設定された濃度に応じて濃縮洗浄液を希釈して用いることが便利である。 <Application of cleaning liquid>
In the present invention, the concentration of the cleaning liquid is set in advance in consideration of the material of the filter to be cleaned and the like, or is appropriately set according to the estimated CT value.
A cleaning solution with a set concentration may be prepared each time, but a concentrated cleaning solution (stock solution) containing each component in the cleaning solution in a predetermined ratio is prepared, and the concentrated cleaning solution is diluted according to the set concentration before use. It is convenient.
　濃縮洗浄液の濃度は、洗浄液の調製（希釈）の便宜性、濃縮洗浄液の取り扱いの安全性等の観点から、濃縮洗浄液中の過酸化水素の濃度として、５モル／Ｌ（１６質量％）以上１５モル／Ｌ（４３質量％）以下が好ましく、７．５モル／Ｌ（２３質量％）以上１０モル／Ｌ（３０質量％）以下がより好ましい。 The concentration of the concentrated cleaning solution is 5 mol/L (16% by mass) or more as the concentration of hydrogen peroxide in the concentrated cleaning solution from the viewpoint of convenience of preparation (dilution) of the cleaning solution, safety of handling the concentrated cleaning solution, and the like. The amount is preferably mol/L (43% by mass) or less, more preferably 7.5 mol/L (23% by mass) or more and 10 mol/L (30% by mass) or less.
　洗浄方法は、循環洗浄、浸漬洗浄等であってよく、これらを組み合わせて用いてもよい。
　なお、洗浄方法が異なると、フィルターの洗浄効率も異なると考えられる、そのため、推定ステップで用いられる積ＣＴ値と差（Ｐ２－Ｐ１）値との関係式は、洗浄方法ごとに設定されることが好ましい。 The cleaning method may be circulation cleaning, immersion cleaning, etc., and these may be used in combination.
It should be noted that if the cleaning method is different, the cleaning efficiency of the filter is also different. Therefore, the relational expression between the product CT value and the difference (P2-P1) value used in the estimation step should be set for each cleaning method. Is preferred.
《フィルター》
　本発明が適用されるフィルターは、原水の精製に用いられるフィルターである。具体的には例えば、精密ろ過膜、限外ろ過膜、ナノろ過膜、逆浸透膜等から選択される１種以上であってよい。
　フィルターの形状は任意である。例えば、平膜状、積層体、蛇腹状、巻回体、中空糸状等であってよい。少ない体積で大きな膜面積を確保できる点で、複数の中空糸状フィルターがパッケージ化された中空糸膜モジュールが好ましい。 "filter"
The filter to which the present invention is applied is a filter used for purification of raw water. Specifically, it may be one or more selected from microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, reverse osmosis membranes and the like.
The shape of the filter is arbitrary. For example, it may have a flat film shape, a laminated body, a bellows shape, a wound body, a hollow fiber shape or the like. A hollow fiber membrane module in which a plurality of hollow fiber filters are packaged is preferable because a large membrane area can be secured with a small volume.
　本発明が適用されるフィルターは、任意の材料から構成されていてよい。例えば、フッ素系樹脂、ポリスルホン系樹脂等から構成されたフィルターであってよい。
　フッ素系樹脂としては、例えば、ポリテトラフルオロエチレン、ポリクロロトリフルオロエチレン、ポリフッ化ビニリデン、ポリフッ化ビニル、ペルフルオロアルコキシフッ素樹脂、四フッ化エチレン－六フッ化プロピレン共重合体、エチレン－四フッ化エチレン共重合体、エチレン－クロロトリフルオロエチレン共重合体等を挙げることができる。
　ポリスルホン系樹脂としては、例えば、ポリスルホン、ポリエーテルスルホン等を挙げることができる。 The filter to which the present invention is applied may be made of any material. For example, it may be a filter made of a fluorine resin, a polysulfone resin, or the like.
Examples of the fluorine resin include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, perfluoroalkoxy fluororesin, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoride. Examples thereof include ethylene copolymers and ethylene-chlorotrifluoroethylene copolymers.
Examples of the polysulfone-based resin include polysulfone and polyether sulfone.
　本発明で用いられる洗浄液は、過酸化水素を含有し、酸化力が強い。そのため、本発明は、耐酸化性の高いフィルターに適用されることが望まれる。したがって、本発明は、フッ素系樹脂によって構成されるフィルターに適用されることが好ましい。
　フッ素系樹脂によって構成されるフィルターを洗浄する場合、洗浄液中の過酸化水素濃度Ｃを１０質量％程度まで高くしても、フィルターの腐食の問題が生ずる可能性は低く維持される。 The cleaning liquid used in the present invention contains hydrogen peroxide and has a strong oxidizing power. Therefore, it is desired that the present invention be applied to a filter having high oxidation resistance. Therefore, the present invention is preferably applied to a filter made of a fluororesin.
When cleaning a filter made of a fluorine-based resin, even if the concentration C of hydrogen peroxide in the cleaning liquid is increased to about 10% by mass, the possibility of the problem of filter corrosion is maintained low.
《原水精製装置》
　本発明が適用されるフィルターは、典型的には例えば、原水精製装置に用いられる限外ろ過膜又は精密ろ過膜であってよい。
　図１に、本発明を好適に適用できる原水精製装置の構成の一例を示した。
　図１の原水精製装置（１００）では、処理される原水（１０）に含まれる比較的粗大な固形分を捕捉して除去するためのストレーナー（１２）、及び限外ろ過膜又は精密ろ過膜（１３）を経て、精製された原水である精製水（１１）が、精製水タンク（１６）に貯蔵される。ストレーナー（１２)の前段階に、例えば、加圧浮上装置、凝集沈殿装置等の前処理装置を更に設置してもよい。 《Raw water purifier》
The filter to which the present invention is applied may typically be, for example, an ultrafiltration membrane or a microfiltration membrane used in a raw water purification apparatus.
FIG. 1 shows an example of the configuration of a raw water purification apparatus to which the present invention can be suitably applied.
In the raw water purification apparatus (100) of FIG. 1, a strainer (12) for capturing and removing relatively coarse solids contained in the raw water (10) to be treated, and an ultrafiltration membrane or a microfiltration membrane ( After 13), purified water (11) which is purified raw water is stored in a purified water tank (16). Before the strainer (12), a pretreatment device such as a pressure flotation device or a coagulating sedimentation device may be further installed.
　原水精製装置は、例えば、海水淡水化装置であってよい。
　図２に、本発明を好適に適用できる原水精製装置の一態様である、海水淡水化装置の構成の一例を示した。
　図２の海水淡水化装置（２００）では、処理される原水である海水（２０）に含まれる比較的粗大な固形分を捕捉して除去するためのストレーナー（２２）、限外ろ過膜又は精密ろ過膜（２３）、一次ろ過水貯蔵タンク（２４）、及び逆浸透膜（２５）を経て、精製された海水である淡水（２１）が淡水タンク（２６）に貯蔵される。ストレーナー（２２)の前段階に、例えば、加圧浮上装置、凝集沈殿装置等の前処理装置を更に設置してもよい。 The raw water purification device may be, for example, a seawater desalination device.
FIG. 2 shows an example of the configuration of a seawater desalination apparatus, which is an aspect of a raw water purification apparatus to which the present invention can be preferably applied.
In the seawater desalination apparatus (200) of FIG. 2, a strainer (22), an ultrafiltration membrane or a precision filter for capturing and removing relatively coarse solids contained in seawater (20) which is raw water to be treated. After passing through the filtration membrane (23), the primary filtered water storage tank (24) and the reverse osmosis membrane (25), purified seawater (21) is stored in the freshwater tank (26). Before the strainer (22), a pretreatment device such as a pressure flotation device or a coagulating sedimentation device may be further installed.
　限外ろ過膜は、例えば、孔径約１ｎｍ以上１０ｎｍ以下のフィルターであってよい。精密ろ過膜は、例えば、孔径約５ｎｍ以上１０μｍ以下のフィルターであってよい。
　本発明は、例えば、上述の原水精製装置（１００）、海水淡水化装置（２００）等に用いられる限外ろ過膜又は精密ろ過膜（１３、２３）に好適に適用することができる。 The ultrafiltration membrane may be, for example, a filter having a pore size of about 1 nm or more and 10 nm or less. The microfiltration membrane may be, for example, a filter having a pore size of about 5 nm or more and 10 μm or less.
INDUSTRIAL APPLICABILITY The present invention can be suitably applied to, for example, the ultrafiltration membrane or the microfiltration membrane (13, 23) used in the above-mentioned raw water purification device (100), seawater desalination device (200) and the like.
《実験例１》
　図２に示した構成の海水淡水化装置における限外ろ過膜を、過酸化水素を含む洗浄液で洗浄したときの、過酸化水素濃度Ｃ及び洗浄時間Ｔの積ＣＴと、洗浄後の透水量Ｐ２及び洗浄前の透水量Ｐ１の差（Ｐ２－Ｐ１）との関係を調べた。
　実施例１に使用した海水淡水化装置（２００）は、ストレーナー（２２）、限外ろ過膜、一次ろ過水貯蔵タンク（２４）、逆浸透膜（２５）、及び淡水タンク（２６）をこの順に有する。 <<Experimental Example 1>>
When the ultrafiltration membrane in the seawater desalination apparatus having the configuration shown in FIG. 2 is washed with a washing liquid containing hydrogen peroxide, the product CT of the hydrogen peroxide concentration C and the washing time T and the permeation amount P2 after washing And the relationship between the difference in the amount of permeation of water P1 before washing (P2-P1) was investigated.
The seawater desalination apparatus (200) used in Example 1 includes a strainer (22), an ultrafiltration membrane, a primary filtered water storage tank (24), a reverse osmosis membrane (25), and a freshwater tank (26) in this order. Have.
　この海水淡水化装置による海水の淡水化を行い、限外ろ過膜の新品時の透水量を１００％としたときの洗浄前透水量Ｐ１（％）、過酸化水素濃度Ｃ（質量％）、及び洗浄時間Ｔ（ｈ）を、それぞれ以下の範囲で変量して、合計１７回の洗浄を行い、それぞれの洗浄後に得られた洗浄後透水量Ｐ２（％）を調べ、横軸が差（Ｐ２－Ｐ１）（％ｐｔ）、縦軸が積ＣＴ（質量％・ｈ）のグラフにプロットした。
　　洗浄前透水量Ｐ１の変量範囲：２０％～９０％
　　過酸化水素濃度Ｃの変量範囲：０．０１質量％～１０質量％
　　洗浄時間Ｔの変量範囲：１０分～２４時間
　使用した洗浄液は、過酸化水素１モルに対して、塩化第一鉄０．２モル（鉄原子換算０．４モル）、及び酒石酸０．０４モル部の割合で含む水溶液を所定の過酸化水素濃度にて調製し、塩酸を加えてｐＨを２．５に調整したうえで用いた。
　洗浄は、循環ろ過洗浄によった。 The seawater is desalinated by this seawater desalination apparatus, and the permeation rate before washing P1 (%), the hydrogen peroxide concentration C (mass %), and the permeation rate of the ultrafiltration membrane when new are 100%, and The washing time T(h) was varied within the following range, and a total of 17 times of washing were performed. The post-washing water permeation rate P2(%) obtained after each washing was examined, and the horizontal axis indicates the difference (P2- P1) (%pt) and the vertical axis is the product CT (mass %.h).
Variable range of water permeability P1 before washing: 20% to 90%
Variable range of hydrogen peroxide concentration C: 0.01% by mass to 10% by mass
Variable range of cleaning time T: 10 minutes to 24 hours The cleaning solution used was 0.2 mol of ferrous chloride (0.4 mol in terms of iron atom) and 0.04 mol of tartaric acid per 1 mol of hydrogen peroxide. An aqueous solution containing 1 part by weight was prepared at a predetermined hydrogen peroxide concentration, and hydrochloric acid was added to adjust the pH to 2.5 before use.
The washing was performed by circulation filtration washing.
　得られたグラフを、図３に示した。
　図３のグラフから、差（Ｐ２－Ｐ１）と積ＣＴ値とが、１本の滑らかな曲線上に乗ることが分かった。差（Ｐ２－Ｐ１）値を説明変数とし、積ＣＴ値を目的変数とする最尤推定により、以下の回帰式が得られた。
　　（ＣＴ［質量％・ｈ］）＝２．４３×１０－８×（Ｐ２－Ｐ１）４．７３
　この回帰曲線の相関係数Ｒ２は、０．９０３と計算されたことから、過酸化水素を含む洗浄液を使用した場合には、差（Ｐ２－Ｐ１）と積ＣＴ値との間に高い相関の回帰式が得られることが検証された。 The graph obtained is shown in FIG.
From the graph of FIG. 3, it was found that the difference (P2-P1) and the product CT value are on a single smooth curve. The following regression equation was obtained by maximum likelihood estimation using the difference (P2-P1) value as the explanatory variable and the product CT value as the objective variable.
(CT [mass %.h])=2.43×10 −8 ×(P2-P1) 4.73
Since the correlation coefficient R 2 of this regression curve was calculated to be 0.903, a high correlation was found between the difference (P2-P1) and the product CT value when the cleaning solution containing hydrogen peroxide was used. It was verified that the regression equation of
　実験例１の海水淡水化装置（２００）において、限外ろ過膜の代わりに精密ろ過膜を用いた場合も、略同様の結果が得られた。 Approximately the same result was obtained when a microfiltration membrane was used instead of the ultrafiltration membrane in the seawater desalination apparatus (200) of Experimental Example 1.
《実験例２》
　洗浄液としては、酒石酸を用いなかった他は、実験例１と同様に調製された洗浄液を用いた。この洗浄液を用い、限外ろ過膜の新品時の透水量を１００％としたときの洗浄前透水量Ｐ１（％）、過酸化水素濃度Ｃ（質量％）、及び洗浄時間Ｔ（ｈ）をそれぞれ変量して行った洗浄の回数を合計８回とした他は、実施例１と同様に洗浄を行い、それぞれの洗浄後に得られた洗浄後透水量Ｐ２（％）を調べ、横軸が差（Ｐ２－Ｐ１）（％ｐｔ）、縦軸が積ＣＴ（質量％・ｈ）のグラフにプロットした。　得られたグラフを、図４に示した。
　図４のグラフから、差（Ｐ２－Ｐ１）と積ＣＴ値とが、１本の滑らかな曲線上に乗ることが分かった。差（Ｐ２－Ｐ１）値を説明変数とし、積ＣＴ値を目的変数とする最尤推定により、以下の回帰式が得られた。
　　（ＣＴ［質量％・ｈ］）＝１．２８×１０－４×（Ｐ２－Ｐ１）２．７０
　この回帰曲線の相関係数Ｒ２は、０．９１２と計算されたことから、過酸化水素を含む洗浄液を使用した場合には、差（Ｐ２－Ｐ１）と積ＣＴ値との間に高い相関の回帰式が得られることが検証された。 <<Experimental example 2>>
As the cleaning liquid, the cleaning liquid prepared in the same manner as in Experimental Example 1 was used except that tartaric acid was not used. Using this cleaning solution, the permeation rate before cleaning P1 (%), the hydrogen peroxide concentration C (mass %), and the cleaning time T (h) are set, respectively, when the water permeability of the new ultrafiltration membrane is 100%. Washing was performed in the same manner as in Example 1 except that the number of washings performed by varying the amount was 8 in total, and the water permeation rate after washing P2 (%) obtained after each washing was examined. P2-P1) (%pt) and the vertical axis is the product CT (mass %.h). The obtained graph is shown in FIG.
From the graph of FIG. 4, it was found that the difference (P2-P1) and the product CT value are on a single smooth curve. The following regression equation was obtained by maximum likelihood estimation using the difference (P2-P1) value as the explanatory variable and the product CT value as the objective variable.
(CT [mass %.h])=1.28×10 −4 ×(P2-P1) 2.70
Since the correlation coefficient R 2 of this regression curve was calculated to be 0.912, a high correlation between the difference (P2-P1) and the product CT value was obtained when the cleaning solution containing hydrogen peroxide was used. It was verified that the regression equation of
《実験例３》
　図１に示した構成の原水精製装置を用いて、河川水の精製を行った後、当該原水精製装置における限外ろ過膜を、過酸化水素を含む洗浄液で洗浄したときの、過酸化水素濃度Ｃ及び洗浄時間Ｔの積ＣＴと、洗浄後の透水量Ｐ２及び洗浄前の透水量Ｐ１の差（Ｐ２－Ｐ１）との関係を調べた。
　実施例３に使用した原水精製装置（１００）は、ストレーナー（１２）、限外ろ過膜、及び精製水タンク（１６）をこの順に有する。
　洗浄液としては、実験例１と同様に調製された洗浄液を用いた。この洗浄液を用い、限外ろ過膜の新品時の透水量を１００％としたときの洗浄前透水量Ｐ１（％）、過酸化水素濃度Ｃ（質量％）、及び洗浄時間Ｔ（ｈ）をそれぞれ変量して行った洗浄の回数を合計７回とした他は、実施例１と同様に洗浄を行い、それぞれの洗浄後に得られた洗浄後透水量Ｐ２（％）を調べ、横軸が差（Ｐ２－Ｐ１）（％ｐｔ）、縦軸が積ＣＴ（質量％・ｈ）のグラフにプロットした。
　得られたグラフを図５に示した。
　図５のグラフから、差（Ｐ２－Ｐ１）と積ＣＴ値とが、１本の滑らかな曲線上に乗ることが分かった。差（Ｐ２－Ｐ１）値を説明変数とし、積ＣＴ値を目的変数とする最尤推定により、以下の回帰式が得られた。
　　（ＣＴ［質量％・ｈ］）＝１．７４×１０－８×（Ｐ２－Ｐ１）４．５８
　この回帰曲線の相関係数Ｒ２は、０．９６２と計算されたことから、過酸化水素を含む洗浄液を使用した場合には、差（Ｐ２－Ｐ１）と積ＣＴ値との間に高い相関の回帰式が得られることが検証された。 <<Experimental example 3>>
Hydrogen peroxide concentration when the ultrafiltration membrane in the raw water purification device was washed with a cleaning liquid containing hydrogen peroxide after the river water was purified using the raw water purification device with the configuration shown in FIG. The relationship between the product CT of C and the cleaning time T and the difference (P2-P1) between the water permeation amount P2 after cleaning and the water permeation amount P1 before cleaning was examined.
The raw water purification apparatus (100) used in Example 3 has a strainer (12), an ultrafiltration membrane, and a purified water tank (16) in this order.
As the cleaning liquid, the cleaning liquid prepared in the same manner as in Experimental Example 1 was used. Using this cleaning solution, the permeation rate before cleaning P1 (%), the hydrogen peroxide concentration C (mass %), and the cleaning time T (h) are set, respectively, when the water permeability of the new ultrafiltration membrane is 100%. Washing was performed in the same manner as in Example 1 except that the number of washings performed by varying the amount was 7 in total, and the permeation rate P2 (%) after washing obtained after each washing was examined. P2-P1) (%pt) and the vertical axis is the product CT (mass %.h).
The obtained graph is shown in FIG.
From the graph of FIG. 5, it was found that the difference (P2-P1) and the product CT value are on a single smooth curve. The following regression equation was obtained by maximum likelihood estimation using the difference (P2-P1) value as the explanatory variable and the product CT value as the objective variable.
(CT [mass %.h])=1.74×10 −8 ×(P2-P1) 4.58
Since the correlation coefficient R 2 of this regression curve was calculated to be 0.962, when the cleaning solution containing hydrogen peroxide was used, there was a high correlation between the difference (P2-P1) and the product CT value. It was verified that the regression equation of
《実験例４》
　洗浄液として次亜塩素酸ナトリウム水溶液を用い、洗浄液中の次亜塩素酸ナトリウム濃度Ｃ’の変量範囲を０．０１質量％～１．０質量％の範囲とした他は、実験例１と同様にして、合計１１回の洗浄を行い、横軸が差（Ｐ２－Ｐ１）、縦軸が積Ｃ’Ｔのグラフにプロットした。
　得られたグラフを、図６に示した。
　図６のグラフを見ると、過酸化水素を含有しない洗浄液を使用した実験例４では、差（Ｐ２－Ｐ１）と積Ｃ’Ｔ値との相関は低いことが分かった。また、次亜塩素酸ナトリウムでは、Ｃ’Ｔ値を上げても回復率は上がらず、十分な洗浄効果が得られなかった。 <<Experimental Example 4>>
The same procedure as in Experimental Example 1 except that an aqueous sodium hypochlorite solution was used as the cleaning liquid, and the variable range of the sodium hypochlorite concentration C′ in the cleaning liquid was set to 0.01% by mass to 1.0% by mass. Then, a total of 11 washes were performed, and plotted on a graph in which the horizontal axis represents the difference (P2-P1) and the vertical axis represents the product C'T.
The obtained graph is shown in FIG.
From the graph of FIG. 6, it was found that in Experimental Example 4 in which the cleaning liquid containing no hydrogen peroxide was used, the correlation between the difference (P2-P1) and the product C′T value was low. Further, with sodium hypochlorite, the recovery rate did not increase even if the C′T value was increased, and a sufficient cleaning effect was not obtained.
　以上のことから、過酸化水素を含有しない洗浄液を使用した実験例４の洗浄では、差（Ｐ２－Ｐ１）値と積ＣＴ値との間の相関は低く、フィルター洗浄条件を決定するための推定は意味をなさないことが分かる。 From the above, in the cleaning of Experimental Example 4 using the cleaning liquid containing no hydrogen peroxide, the correlation between the difference (P2-P1) value and the product CT value is low, and it is estimated to determine the filter cleaning condition. It turns out that does not make sense.
　これに対して、過酸化水素を含有する洗浄液を使用した実験例１～３の洗浄では、洗浄液中の過酸化水素濃度をＣ、洗浄時間をＴ、前記フィルターの洗浄前の透水量をＰ１、及び洗浄後の透水量をＰ２としたときに、
　　差（Ｐ２－Ｐ１）値から積ＣＴ値を推定するステップ、及び
　　積ＣＴ値から差（Ｐ２－Ｐ１）値を推定するステップ
のうちのいずれかの推定ステップを経由することにより、最小量の洗浄液及び最短の洗浄時間によって最大の洗浄効果を得るための、フィルター洗浄条件を決定することができることが検証された。 On the other hand, in the cleaning of Experimental Examples 1 to 3 using the cleaning liquid containing hydrogen peroxide, the concentration of hydrogen peroxide in the cleaning liquid was C, the cleaning time was T, the water permeation amount before cleaning the filter was P1, And when the water permeability after washing is P2,
A minimum amount of cleaning liquid is obtained by going through one of the steps of estimating the product CT value from the difference (P2-P1) value and estimating the difference (P2-P1) value from the product CT value. It was verified that the filter washing conditions for obtaining the maximum washing effect can be determined with the shortest washing time.
　１０　　原水
　１１　　精製水
　１２、２２　　ストレーナー
　１３、２３　　限外ろ過膜又は精密ろ過膜
　１６　　精製水タンク
　２０　　海水
　２１　　淡水
　２４　　一次ろ過水貯蔵タンク
　２５　　逆浸透膜
　２６　　淡水タンク
　１００　　原水精製装置
　２００　　海水淡水化装置 10 Raw Water 11 Purified Water 12, 22 Strainer 13, 23 Ultrafiltration Membrane or Microfiltration Membrane 16 Purified Water Tank 20 Seawater 21 Fresh Water 24 Primary Filtration Water Storage Tank 25 Reverse Osmosis Membrane 26 Fresh Water Tank 100 Raw Water Purification Equipment 200 Seawater Desalination Equipment

Claims (13)

  1. 　原水の精製に用いられるフィルターを、過酸化水素を含有する洗浄液で洗浄するための、フィルター洗浄条件の決定方法であって、
    　洗浄液中の過酸化水素濃度をＣ、洗浄時間をＴ、前記フィルターの洗浄前の透水量をＰ１、及び洗浄後の透水量をＰ２としたときに、
    　　差（Ｐ２－Ｐ１）値から積ＣＴ値を推定するステップ、及び
    　　積ＣＴ値から差（Ｐ２－Ｐ１）値を推定するステップ
    のうちのいずれかの推定ステップを含む、フィルター洗浄条件の決定方法。     A method for determining filter cleaning conditions, for cleaning a filter used for purification of raw water with a cleaning solution containing hydrogen peroxide,
    When the hydrogen peroxide concentration in the cleaning liquid is C, the cleaning time is T, the water permeability of the filter before cleaning is P1, and the water permeability after cleaning is P2,
    A method for determining filter cleaning conditions, comprising: an estimation step of a product CT value from the difference (P2-P1) value; and an estimation step of estimating a difference (P2-P1) value from the product CT value.
  2. 　前記原水が、海水、河川水、湖沼水、地下水、下水、又は工業排水である、請求項１に記載のフィルター洗浄条件の決定方法。 The method for determining filter cleaning conditions according to claim 1, wherein the raw water is seawater, river water, lake water, groundwater, sewage, or industrial wastewater.
  3. 　前記推定ステップが、
    　積ＣＴ値と差（Ｐ２－Ｐ１）値との関係式を用いて行われる、請求項１又は２に記載のフィルター洗浄条件の決定方法。     The estimation step is
    The method for determining filter washing conditions according to claim 1 or 2, which is performed using a relational expression between a product CT value and a difference (P2-P1) value.
  4. 　前記関係式が、積ＣＴ値及び差（Ｐ２－Ｐ１）値のうちの、いずれかを説明変数とし、他方を目的変数とする最尤推定によって得られた回帰式である、請求項３に記載のフィルター洗浄条件の決定方法。 4. The relational expression according to claim 3, wherein the relational expression is a regression expression obtained by maximum likelihood estimation using one of a product CT value and a difference (P2-P1) value as an explanatory variable and the other as an objective variable. Method for determining filter cleaning conditions in.
  5. 　前記説明変数が複数の領域に分割されており、前記説明変数の領域ごとに回帰式がそれぞれ設定される、請求項４に記載のフィルター洗浄条件の決定方法。 The method for determining filter cleaning conditions according to claim 4, wherein the explanatory variable is divided into a plurality of regions, and a regression equation is set for each region of the explanatory variable.
  6. 　前記推定ステップが、差（Ｐ２－Ｐ１）値から積ＣＴ値を推定するステップであり、
    　推定された積ＣＴ値に基づいて、所定の過酸化水素濃度Ｃから洗浄時間Ｔが決定される、請求項１～５のいずれか一項に記載のフィルター洗浄条件の決定方法。     The estimating step is a step of estimating a product CT value from a difference (P2-P1) value,
    The method for determining filter cleaning conditions according to any one of claims 1 to 5, wherein the cleaning time T is determined from a predetermined hydrogen peroxide concentration C based on the estimated product CT value.
  7. 　前記推定ステップが、差（Ｐ２－Ｐ１）値から積ＣＴ値を推定するステップであり、
    　推定された積ＣＴ値に基づいて、所定の洗浄時間Ｔから過酸化水素濃度Ｃが決定される、請求項１～５のいずれか一項に記載のフィルター洗浄条件の決定方法。     The estimating step is a step of estimating a product CT value from a difference (P2-P1) value,
    The method for determining filter cleaning conditions according to any one of claims 1 to 5, wherein the hydrogen peroxide concentration C is determined from a predetermined cleaning time T based on the estimated product CT value.
  8. 　前記推定ステップが、積ＣＴ値から差（Ｐ２－Ｐ１）値を推定するステップであり、
    　推定された差（Ｐ２－Ｐ１）値に基づいて、所定の洗浄後の透水量Ｐ２から洗浄前の透水量Ｐ１が決定される、請求項１～５のいずれか一項に記載のフィルター洗浄条件の決定方法。     The estimating step is a step of estimating a difference (P2-P1) value from the product CT value,
    The filter cleaning condition according to any one of claims 1 to 5, wherein the water permeation amount P1 before the cleaning is determined from the water permeation amount P2 after the predetermined cleaning, based on the estimated difference (P2-P1) value. How to decide.
  9. 　前記推定ステップが、積ＣＴ値から差（Ｐ２－Ｐ１）値を推定するステップであり、
    　推定された差（Ｐ２－Ｐ１）値に基づいて、検知された透水量Ｐ１値から洗浄後の透水量Ｐ２が決定される、請求項１～５のいずれか一項に記載のフィルター洗浄条件の決定方法。     The estimating step is a step of estimating a difference (P2-P1) value from the product CT value,
    The filter cleaning condition according to any one of claims 1 to 5, wherein the water permeation amount P2 after cleaning is determined from the detected water permeation amount P1 value based on the estimated difference (P2-P1) value. How to decide.
  10. 　前記原水の精製に用いられるフィルターが、精密ろ過膜、限外ろ過膜、ナノろ過膜、又は逆浸透膜である、請求項１～９のいずれか一項に記載のフィルター洗浄条件の決定方法。 The method for determining filter washing conditions according to any one of claims 1 to 9, wherein the filter used for purifying the raw water is a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, or a reverse osmosis membrane.
  11. 　前記洗浄液が、過酸化水素水、又は過酸化水素及び鉄化合物を含有する洗浄液である、請求項１～１０のいずれか一項に記載のフィルター洗浄条件の決定方法。 The method for determining filter cleaning conditions according to any one of claims 1 to 10, wherein the cleaning liquid is a hydrogen peroxide solution or a cleaning liquid containing hydrogen peroxide and an iron compound.
  12. 　前記過酸化水素及び鉄化合物を含む洗浄液が、ヒドロキシジカルボン酸を更に含有する、請求項１１に記載のフィルター洗浄条件の決定方法。 The method for determining filter cleaning conditions according to claim 11, wherein the cleaning liquid containing the hydrogen peroxide and the iron compound further contains hydroxydicarboxylic acid.
  13. 　前記原水が、海水又は河川水である、請求項１～１２のいずれか一項に記載のフィルター洗浄条件の決定方法。 The method for determining filter cleaning conditions according to any one of claims 1 to 12, wherein the raw water is seawater or river water.
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US5198116A (en) * 1992-02-10 1993-03-30 D.W. Walker & Associates Method and apparatus for measuring the fouling potential of membrane system feeds
JPH06506609A (en) * 1991-04-16 1994-07-28 ヘンケル・コマンディットゲゼルシャフト・アウフ・アクチェン Cleaning method and equipment for carrying out the method
WO2008120509A1 (en) * 2007-04-03 2008-10-09 Asahi Kasei Chemicals Corporation Washing agent for separation membrane, process for producing the same and method of washing
JP2008296109A (en) * 2007-05-30 2008-12-11 Hitachi Plant Technologies Ltd Method for calculating cleaning time necessary for cleaning pipe, method for calculating parameters, and support method for designing cleaning of pipe
JP2011212540A (en) * 2010-03-31 2011-10-27 Kurita Water Ind Ltd Device for selecting cleaning conditions and method for selecting cleaning conditions
US20130060384A1 (en) * 2010-04-19 2013-03-07 Abb Research Ltd Method and system for optimizing membrane cleaning process
JP2017018859A (en) * 2015-07-07 2017-01-26 株式会社東芝 Membrane washing control method, membrane washing control device, and water treatment system

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06506609A (en) * 1991-04-16 1994-07-28 ヘンケル・コマンディットゲゼルシャフト・アウフ・アクチェン Cleaning method and equipment for carrying out the method
US5198116A (en) * 1992-02-10 1993-03-30 D.W. Walker & Associates Method and apparatus for measuring the fouling potential of membrane system feeds
WO2008120509A1 (en) * 2007-04-03 2008-10-09 Asahi Kasei Chemicals Corporation Washing agent for separation membrane, process for producing the same and method of washing
JP2008296109A (en) * 2007-05-30 2008-12-11 Hitachi Plant Technologies Ltd Method for calculating cleaning time necessary for cleaning pipe, method for calculating parameters, and support method for designing cleaning of pipe
JP2011212540A (en) * 2010-03-31 2011-10-27 Kurita Water Ind Ltd Device for selecting cleaning conditions and method for selecting cleaning conditions
US20130060384A1 (en) * 2010-04-19 2013-03-07 Abb Research Ltd Method and system for optimizing membrane cleaning process
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