JP2016165708A - Evaluation method of membrane clogging property of water to be treated, membrane treating device and its operation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for evaluating water to be treated by measuring accurately, simply and quickly a membrane clogging degree evaluation index included in the water to be treated such as raw city water.SOLUTION: There is provided an evaluation method of membrane clogging property of water to be treated that is treated by a separation membrane. In the evaluation method of the membrane clogging property of the water to be treated, after measuring a nanoparticle number concentration in the water to be treated, the membrane clogging property of the water to be treated is evaluated from a relation between the nanoparticle number concentration determined beforehand and a membrane clogging degree evaluation index.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for evaluating water to be treated, a membrane treatment apparatus, and an operation method thereof.

Membrane filtration devices using ultrafiltration membranes or microfiltration membranes have a separation membrane in the pressure vessel, and the separation membrane separates the vessel into the raw water side and the permeate side (filtrated water side). The raw water is pressurized and introduced to the side by a pump, and permeate is obtained from the permeate side by membrane filtration.
Particularly in recent years, due to problems of pathogenic microorganisms such as Cryptosporidium, application to water purification treatment using river water and groundwater as raw water is progressing.

In such a membrane filtration device, the components contained in the raw water adhere to and deposit on the raw water side membrane surface and membrane pores of the separation membrane, contaminating the separation membrane, and the filtration performance gradually deteriorates due to continuous use.
Substances that cause membrane contamination in purification treatment are said to be organic matter, iron, manganese, aluminum, silica, etc. Currently, when selecting operating conditions such as membrane permeation flux, these substances in raw water It is often determined empirically from the results and past results.

Organic substances are the most important membrane contaminants as the cause of membrane contamination. Total organic carbon (TOC) is used as the water quality indicator, but even when the raw water has the same TOC value, the rate of increase in the filtration resistance of the membrane is often different. Because of differences, it is not uncommon for problems such as increased frequency of chemical cleaning.
The same applies to the operation management, and there is a case where the film contamination rapidly proceeds even though the TOC concentration does not change. This is because the organic matter that causes film contamination is an extremely small part of the TOC component, and its concentration is low, so that the change cannot be detected even if the TOC is measured.

  As a method for evaluating the membrane blockage of the separation membrane supply water in the overall rather than the individual water quality such as TOC, there is a method using the fouling index (FI value) defined in JIS K3802, etc. The index is basically an index that assumes the evaluation of the water supplied to the reverse permeable membrane device. In the tap water with several degrees of turbidity, the FI value is the same and is not suitable as an evaluation method.

In addition, as a related conventional method, for example, Patent Document 1 describes a membrane permeation flux, a physical cleaning interval, a function of a turbid mass of membrane feed water and a measured value of dissolved organic carbon (DOC) and a membrane permeation flux. A method for optimizing the chemical cleaning interval and pretreatment conditions is described. However, in this method, it is necessary to analyze DOC, ultraviolet absorbance (E260), and turbidity, and since it uses a relatively difficult theoretical formula, it is complicated and not versatile. In addition, this method limits the cause of contamination from organic components to humic substances, and simply calculates the rate of progress of membrane contamination from the ratio of DOC and E260, so that organic components other than humic substances are involved in membrane contamination. Cannot be evaluated correctly.
In recent researches, it has been clarified that the important organic substances involved in membrane contamination in water purification treatment are polysaccharides rather than humic substances that express UV absorbance. The method described in 1 is lacking in validity.

  Further, Patent Document 2 and Patent Document 3 also describe that the coagulation treatment and the like are controlled based on humic substances such as raw water, membrane supply water, and membrane filtered water, and ultraviolet absorbance (E260). This is a driving method that lacks rationality.

This inventor repeated earnest research and developed "Fouling Potential (FP)" which is a new parameter | index regarding the film | membrane obstruction | occlusion organic substance in film | membrane supply waters, such as raw water supply of a nonpatent literature 1-4.
This index is an index that gives useful information regarding the abundance and molecular weight of the membrane clogging organic matter in the raw water supply water or the membrane supply water that has been pretreated therefor, that is, polysaccharides.

  In addition, the sample amount necessary for FP measurement is about 500 to 1000 mL, which is almost the same as the sample amount necessary for the jar test generally performed for selecting the flocculant injection rate in the water purification treatment. This is one of the very effective indices that enables the quantitative measurement of the amount of decrease in the amount of the membrane occluding substance due to the agglomeration process by continuously measuring the FP after performing the above.

  In addition, as the inventor has reported in Non-Patent Documents 1 to 4, the abundance of membrane clogging substances represented by fouling potential (FP) in natural water such as raw water for tap water is river water, lakes and lakes. It varies depending on the water source such as water, and seasonal variations occur. If it does not fluctuate every day and shows a constant value for several months depending on the characteristics of the water source, it is necessary to measure the evaluation index of the membrane occlusion material represented by fouling potential (FP) every day. Instead, it may be measured several times during a certain period. For example, by measuring the ultraviolet absorbance (E260) that can be easily measured by the method described in Patent Document 4 and evaluating the degree of membrane occlusion of the membrane feed water from the removal rate, the fouling potential (FP) can be calculated very easily. It is possible to grasp.

JP 2001-327967 A JP 2001-170458 A JP 2008-126223 A JP 2013-228846 A

Koji Kashimada and one other, “Proposal of Fouling Potential in Water Treatment and Its Characteristic Evaluation (I)”, Proceedings of the 60th National Waterworks Research Conference, Japan Water Works Association, May 2009, p. 134-135 Yoshihide Kaitani and one other, “Proposal of Fouling Potential in Water Treatment and Its Characteristic Evaluation (II)”, Proceedings of the 60th National Waterworks Research Conference, Japan Waterworks Association, May 2009, p. 136-137 Yoshihide Kaitani and one other, “Proposal of Fouling Potential in Water Purification and Its Characteristic Evaluation (III)”, 61st National Waterworks Research Conference Lecture, Japan Waterworks Association, May 2010, p. 252-253 Yoshihide Kaitani and one other, “Proposal of Fouling Potential in Water Treatment and Its Characteristic Evaluation (IV)”, 62nd National Waterworks Research Presentation Lecture, Japan Waterworks Association, May 2011, p. 352-353

  As described above, FP measurement does not involve a relatively complicated operation and requires a small amount of sample. However, although the measurement time depends on the amount of the membrane-occluding substance in the sample, it is typically about 1 to 3 hours. Therefore, it is not necessarily suitable as a continuous monitoring index in the field. In addition, when the number of samples increases, it takes a lot of time to determine the optimum processing conditions.

  Also, when the water quality changes abruptly in units of time, such as during rainy and snowmelt periods, including typhoons, etc., operating conditions are determined by determining the membrane occlusion evaluation index in a short time and evaluating the membrane occlusion of the treated water. It will be necessary to determine.

  As described above, according to the conventional method, the content of the membrane-occluding substance contained in the water to be treated such as raw water for tap water cannot be measured accurately, simply and quickly. Accordingly, it has been difficult to continuously operate the membrane processing apparatus without any trouble.

  An object of the present invention is to accurately and easily measure a membrane plugging substance contained in water to be treated, such as raw water for water supply, quickly, and to evaluate the water to be treated, a membrane treatment apparatus having means for performing the evaluation, Another object of the present invention is to provide a method for operating the film processing apparatus.

  The present inventor has intensively studied to solve the above-mentioned problems, and the polysaccharide-like substance has a much more significant effect on the membrane occlusion than the UV light-absorbing substance and has a correlation with the membrane occlusion of the water to be treated. It has been found that the higher is not the amount of the substance exhibiting UV absorbance, but the amount of the polysaccharide-like substance. In recent years, there has been a rapid correlation between the nanoparticle number concentration and the membrane occlusion evaluation index typified by FP, using several nanoparticle measurement methods that have been rapidly advanced in measurement technology. The headline and the present invention were completed.

The present invention is a method for evaluating the membrane clogging property of water to be treated that is treated using a separation membrane, and after measuring the concentration of nanoparticles in the water to be treated, the concentration of the number of nanoparticles and the degree of membrane clogging obtained in advance are measured. This is a method for evaluating the membrane blocking property of the water to be treated, which evaluates the membrane blocking property of the water to be treated from the relationship with the evaluation index.
Hereinafter, such a method for evaluating the water blocking property of water to be treated is also referred to as “the evaluation method of the present invention”.

  The evaluation method of the present invention includes the nanoparticle tracking analysis method (NTA), laser induced breakdown detection method (LIDB), electrical resistance nanopulse method (TRPS), or dynamic light scattering method (DLS). It is preferable to measure the particle number concentration.

  The evaluation method of the present invention preferably measures the nanoparticle number concentration of less than 450 nm in the water to be treated.

  In the evaluation method of the present invention, the wavelength of the laser used in the nanoparticle tracking analysis method (NTA) is preferably 488 nm or 405 nm.

In the evaluation method of the present invention, the membrane occlusion degree evaluation index is preferably FP, MFI (MFI _0.45 ), MFI-UF, MFI-NF, CFS-MFI _UF, or UMFI.

Moreover, the present invention is a membrane treatment apparatus for obtaining filtered water by treating treated water using a separation membrane, comprising a nanoparticle number concentration measuring means for measuring the nanoparticle number concentration of the treated water. And determining the membrane occlusion degree evaluation index from the nanoparticle number concentration obtained by the nanoparticle number concentration measuring means based on the relationship between the nanoparticle number concentration and the membrane occlusion degree evaluation index determined in advance. It is a membrane processing apparatus that can evaluate the water blocking properties of water and select operating conditions.
Hereinafter, such a film processing apparatus is also referred to as “the apparatus of the present invention”.

Furthermore, the present invention is a method for operating a membrane treatment apparatus for obtaining filtered water by treating treated water using a separation membrane, the nanoparticle number concentration measuring step for measuring the nanoparticle number concentration of the treated water And determining the membrane occlusion degree evaluation index from the nanoparticle number concentration obtained by the nanoparticle number concentration measurement step based on the relationship between the nanoparticle number concentration and the membrane occlusion degree evaluation index determined in advance. An operation condition selection step for evaluating the membrane blocking property and selecting an operation condition.
Hereinafter, such an operation method of the membrane treatment apparatus is also referred to as “operation method of the present invention”.

  Since the nanoparticle number concentration can be measured very easily and quickly, according to the present invention, the membrane clogging degree evaluation index contained in the water to be treated such as raw water for tap water can be accurately, easily and quickly (for example, In a short time of about 5 to 15 minutes, it is possible to provide a method for measuring and evaluating the water to be treated, a membrane treatment apparatus provided with means for performing the assessment, and a method for operating the membrane treatment apparatus.

2 is a graph obtained in Example 1. 6 is a graph obtained in Example 2.

<Evaluation method of the present invention>
The evaluation method of the present invention will be described.
In the evaluation method of the present invention, the concentration of nanoparticles in water to be treated is measured.
The measurement of the number concentration of nanoparticles is not limited in terms of analysis principle and measurement conditions as long as nanoparticles of 100 nm or less can be evaluated. Nanoparticle tracking analysis method (NTA), laser-induced breakdown detection method (LIDB), electric resistance nanopulse method (TRPS) or dynamic light scattering (DLS) is preferred.

The nanoparticle tracking analysis method (NTA) will be described.
Nanoparticle tracking analysis method, also called nanoparticle tracking analysis method, uses the fact that the speed of the Brownian motion of the particle depends on the particle diameter, and measures the Brownian motion pattern of the particle using NTA (Nano Tracking Analysis) technology. This is a method for obtaining a particle size distribution graph of particle diameter and number.
For example, the description is described in JP-T-2014-521967.
The nanoparticle tracking analysis method may be abbreviated as PTA.

The laser induced breakdown detection method (LIDB, Laser Induced Breakdown Detection) will be described.
In the laser-induced breakdown detection method, a nanosecond pulsed laser is focused on a liquid containing the nanoparticles to be detected, and the plasma generated each time the nanoparticles cross the laser beam is detected by a sensor. This is a method of deriving the size distribution and concentration from statistical values.

The electrical resistance nanopulse method (TRPS, Tunable Resistive Pulse Sensor) will be described.
In the electric resistance nanopulse method, when a voltage is applied to a solution sandwiching nanopores, nanoparticles contained in the solution pass through pores, and the volume of the particles is obtained from the electric resistance nanopulse generated at that time (for example, a long length) This is a method in which particles become larger in volume as a pulse).
For example, the description is described in JP-T-2013-518268.

The dynamic light scattering method (DLS) will be described.
Dynamic light scattering (DLS), also known as quasi-elastic light scattering (QELS), utilizes the Brownian motion of particles or molecules in suspension to scatter laser light at different intensities. Since the speed of Brownian motion can be obtained by analyzing the change, this is a method of obtaining the particle size using the Stokes-Einstein equation.
For example, the description is described in JP-T-2014-521967.

In the present invention, a conventional analyzer using a laser with a wavelength of 630 to 680 nm may not be able to measure the concentration of the number of nanoparticles evaluated in the present invention.
When measuring the nanoparticle number concentration by dynamic light scattering (DLS), measure the nanoparticle number concentration of the water to be treated by setting the laser wavelength to 600 nm or less or increasing the laser output. be able to.

  In the evaluation method of the present invention, the measurement of the concentration of nanoparticles in the water to be treated is preferably performed by a nanoparticle tracking analysis method (NTA). In the nanoparticle tracking analysis method (NTA), the wavelength of the laser used is preferably 500 nm or less, more preferably 488 nm, and even more preferably 405 nm. When using a laser wavelength of 405 nm, the price of the device may be high.

  In the evaluation method of the present invention, it is preferable to measure the nanoparticle number concentration in the water to be treated of less than 450 nm, preferably less than 400 nm, more preferably less than 200 nm, and still more preferably less than 100 nm by the method as described above.

In the evaluation method of the present invention, after measuring the nanoparticle number concentration of the water to be treated as described above, from the relationship between the nanoparticle number concentration and the membrane clogging degree evaluation index determined in advance, the membrane clogging of the water to be treated Assess sex.
The present inventor has intensively studied and found that the membrane blockage degree evaluation index represented by fouling potential (FP) and the nanoparticle number concentration have a high correlation (for example, a proportional relationship with a high correlation coefficient). . Therefore, if the relationship between the nanoparticle number concentration and the membrane occlusion degree evaluation index is obtained in advance, the membrane occlusion degree evaluation index can be obtained with high accuracy by measuring the nanoparticle number concentration, and the membrane of the water to be treated The occlusive property can be evaluated.

The membrane occlusion degree evaluation index will be described.
Preferable examples of the membrane occlusion degree evaluation index include fouling potential (FP), MFI (MFI _0.45 ), MFI-UF, MFI-NF, CFS-MFI _UF and UMFI. However, other methods for evaluating the degree of blockage of water to be treated may be used.

A method for measuring the fouling potential (FP) will be described.
First, a hydrophobic PVDF membrane having a nominal pore size of 0.22 μm is prepared as a separation membrane, and this separation membrane is attached to a stirring type pressure cell. The rotating speed of the stirring bar of the cell is 1,450 rpm, and the whole volume is constant rate filtration. Under the condition of (membrane permeation flux 20 m / day), the water to be treated was subjected to pressure filtration, and after the membrane differential pressure increased, the separation membrane was removed from the cell and washed with 1% -oxalic acid (washing time 60). (Preferably further cleaning of the membrane surface using a sponge), and then again mounting the separation membrane after the oxalic acid cleaning on the cell and then applying the pressure Filtration is performed using the filtrate produced by filtration, and the membrane pressure difference is measured again. The difference between the membrane pressure difference and the membrane pressure difference at the start of filtration (m-Aq, at 25 ° C.) divided by the total amount of filtered water (m ³ / m ² -membrane) is the fouling potential of treated water ( FP).

MFI (MFI _0.45 ), MFI-UF, MFI-NF, and CFS-MFI _UF will be described.
MFI (Modified Fouling Index) uses a membrane filter (generally manufactured by Millipore, cellulose mixed ester (TYPE HA)) having an average pore size of 0.45 μm and a diameter of 47 mm, and water to be treated at a pressure of 2.0 bar (200 kPa). Pass water and filter.
The horizontal axis and vertical axis of the graph are plotted as filtration test results at 20 ° C., with the filtered water amount: V (l) and the filtration time / filtered water amount: t / V (s / l), respectively, and the t / V-V curve. The slope of the part that becomes a straight line is calculated, and the value is defined as MFI.
MFI-UF (Modified Fouling Index-Ultrafiltration) is a case where measurement is performed using a UF membrane, and there is an example in which a UF membrane having a molecular weight cut off of 13,000 daltons is used.
MFI-NF (Nanofiltration-Modified Fouling Index) is a case where measurement is performed using an NF membrane, and there is an example using an NF membrane of 500 to 1500 daltons.
CFS-MFI _UF (Crossflow Sampler-Modified Fouling Index-Ultrafiltration) uses a cross-flow filtration type membrane filtration device as a pretreatment of test water to be supplied to the MFI-UF method. This is a method of supplying to a legal evaluation device.
Reference materials: Desalination, Vol.32, pp.137-148 (1980)
Reference materials: Journal of Membrane Science, Vol.197, pp.1-21 (2002)
Reference materials: Desalination, Vol.192, pp.1-7 (2006)
Reference materials: Water Research, Vol.45, pp.1639-1650 (2011)

UMFI will be described.
The UMFI (Unified Membrane Fouling Index) is a method of creating a mini-module with a membrane actually used and performing a filtration test using the mini-module. Therefore, the filtration conditions are selected depending on the membrane used, the operating conditions of the actual machine, and the like.
Since an actual membrane filtration apparatus is often operated by constant speed filtration, constant speed filtration is often employed in filtration tests.
Since the cake filtration theory can be applied, the cake filtration constant is calculated and set as UMFI.
Reference: Environ. Sci. Technol., Vol.42, pp.714-720 (2008)

In the evaluation method of the present invention, the water to be treated is not particularly limited as long as it is water treated using a separation membrane.
Here, the separation membrane is not limited. Examples of the separation membrane include an ultrafiltration membrane (UF membrane), a microfiltration membrane (MF membrane), a reverse osmosis membrane (RO membrane), and a nanofiltration membrane (NF membrane).
Specific examples of water to be treated include raw water for rivers (river water, groundwater, etc.), seawater, and biologically treated water.

Before subjecting the water to be treated to the evaluation method of the present invention, it is preferable to remove particles having a particle size of 0.45 μm or more as a pretreatment. Is the membrane clogging substance used in membrane filtration processes used for water purification, membrane separation activated sludge process (MBR), seawater desalination (RO membrane and its pretreatment MF membrane and UF membrane), water treatment, etc., equal to the membrane pore size? It is a smaller substance, and its size is about 0.1 to 0.2 μm or less. However, when they are analyzed with a nanoparticle analyzer, particles of 0.45 μm or more can be a hindrance to measurement. Because. As a means for removing particles having a particle diameter of 0.45 μm or more before being subjected to the evaluation method of the present invention for the water to be treated, a means for filtering with a membrane filter having a pore diameter of about 0.45 μm is preferable. The pore diameter of the membrane (membrane filter, etc.) used for the pretreatment is not limited to 0.45 μm unless the nanoparticles to be evaluated are removed by the pretreatment, more preferably 0.22 μm, and 0.2 μm. More preferred is 0.1 μm. This is because interfering substances can be removed more and only nanoparticles that affect membrane blockage tend to be measured. However, if pretreatment is performed using a film having a pore size that is too small, nanoparticles to be evaluated may be removed by the pretreatment.
The membrane used for the pretreatment is preferably a hydrophilic membrane, more preferably a membrane made of PVDF, PES, or PS that has been subjected to a hydrophilic treatment, and may be CA, which is a hydrophilic material.

<Apparatus of the present invention, operation method of the present invention>
Next, the apparatus of the present invention will be described.
The apparatus of this invention has a nanoparticle number concentration measuring means for measuring the nanoparticle number concentration of the said to-be-processed water.
As a nanoparticle number concentration measuring means, the nanoparticle tracking analysis method (NTA), laser induced breakdown detection method (LIDB), electric resistance nanopulse method (TRPS) or dynamic light scattering method (DLS) in the evaluation method of the present invention described above. ) Can be used.

  As in the case of the evaluation method of the present invention described above, such an apparatus of the present invention uses the nanoparticle number concentration measuring means based on the relationship between the nanoparticle number concentration determined in advance and the membrane occlusion degree evaluation index. Obtaining a membrane clogging degree evaluation index from the obtained nanoparticle number concentration, and evaluating the membrane clogging property of the water to be treated accurately, easily and quickly (for example, in a short time of about 5 to 15 minutes). Can do. As a result, the operating conditions (membrane permeation flux, frequency of chemical cleaning, etc.) can be selected so as to be quickly optimized, so that the apparatus can be operated without any trouble.

  Moreover, such an apparatus of the present invention can implement the operation method of the present invention.

  In addition, in the apparatus of the present invention and the operation method of the present invention, the measurement method of the nanoparticle number concentration, the wavelength of the laser used in the nanoparticle tracking analysis method (NTA), the particle diameter of the nanoparticle, the evaluation index of the membrane occlusion, etc. The aspect can be the same as in the evaluation method of the present invention.

  Examples of the present invention will be described below. The present invention is not limited to the following examples.

<Example 1>
Several types of raw tap water were prepared and filtered using a 0.45 μm membrane filter as test water. And about each test water, the fouling potential (FP) and the nanoparticle number density | concentration were measured.

A method for measuring the fouling potential (FP) will be described.
First, a hydrophobic PVDF membrane (Millipore, GVHP, diameter 25 mm) having a nominal pore size of 0.22 μm was used, and this was attached to a stirring type pressure cell, and pressure filtration was performed with a liquid feed pump for HPLC. . Filtration is performed by constant volume filtration (membrane permeation flux 20 m / day) while rotating the stirring bar of the cell at 1,450 rpm. After the membrane differential pressure has risen to some extent, the membrane is removed from the cell and 1%- Oxalic acid cleaning (cleaning time 60 minutes, cleaning temperature about 20 ° C.) and sponge cleaning of the membrane surface were performed. After washing, the membrane was attached to the cell, filtered with GVHP membrane filtered water of the test water, and the membrane differential pressure was measured again. The difference between the membrane pressure difference and the membrane pressure difference at the start of filtration (m-Aq, at 25 ° C.) divided by the total amount of filtered water (m ³ / m ² -membrane) is the fouling potential (FP) of the test water. It was.

The nanoparticle number concentration (pieces / mL) was determined by nanoparticle tracking analysis (NTA).
Specifically, Zeta View PMX110 manufactured by Microtrack Co. was used. In the measurement, a laser wavelength of 488 nm was used.
As a result of the measurement, the peak particle size was 0.12 μm.

A graph showing the relationship between the measured FP of each test water and the nanoparticle number concentration is shown in FIG.
As shown in FIG. 1, it was found that FP and the nanoparticle number concentration show a high correlation coefficient.
Therefore, if FIG. 1 is used, it can be said that FP can be known accurately by measuring the nanoparticle number concentration.

<Example 2>
The nanoparticle number concentration was evaluated with an analyzer (manufactured by PMX: ZetaView PMX110, specification: laser wavelength 488 nm, laser output 40 mW) based on the nanoparticle tracking analysis method (NTA) as a measurement principle.
As samples, raw tap water (20 types) and aggregated treated water A or B of tap raw water were used.
These agglomerated treated water was obtained by adding polyaluminum chloride (PAC) to each of two kinds of river water (raw water), rapidly stirring (130 rpm × 3 minutes), and allowing to stand for 3 minutes. In addition, several agglomerated waters with different PAC addition amounts were prepared.
Analysis was performed after each sample was pretreated with a 0.45 μm membrane filter.
FIG. 2 shows the relationship between the measurement results of the nanoparticle number concentration measured by the nanoparticle analyzer and the FP which is a membrane blockage degree evaluation index. The FP was measured by the same method as in Example 1.

As shown in FIG. 2, it was found that FP and nanoparticle number concentration have a high correlation coefficient.
Therefore, if FIG. 2 is used, it can be said that FP of to-be-processed water can be calculated | required accurately by measuring a nanoparticle number density | concentration.

Claims (7)

A method for evaluating the membrane blocking properties of water to be treated using a separation membrane,
After measuring the nanoparticle number concentration of the water to be treated, the membrane clogging of the water to be treated is evaluated from the relationship between the nanoparticle number concentration determined in advance and the membrane clogging degree evaluation index. Evaluation method of sex.   The nanoparticle number concentration of the treated water is measured by a nanoparticle tracking analysis method (NTA), a laser-induced breakdown detection method (LIDB), an electric resistance nanopulse method (TRPS), or a dynamic light scattering method (DLS). The evaluation method of the film | membrane blockability of the to-be-processed water of Claim 1.   The evaluation method of the film obstruction | occlusion property of the to-be-processed water of Claim 1 or 2 which measures the said nanoparticle number density | concentration of less than 450 nm in the to-be-processed water.   The evaluation method of the film obstruction | occlusion property of the to-be-processed water in any one of Claims 1-3 whose wavelength of the laser used in the said nanoparticle tracking analysis method (NTA) is 488 nm or 405 nm. The membrane closure degree evaluation _{index, FP, MFI (MFI 0.45)} , an MFI-UF, MFI-NF, CFS-MFI UF or UMFI, membrane clogging of the water to be treated according to any one of claims 1 to 4 Evaluation method of sex. A membrane treatment device for treating filtered water using a separation membrane to obtain filtered water,
Having a nanoparticle number concentration measuring means for measuring the nanoparticle number concentration of the water to be treated;
Based on the relationship between the nanoparticle number concentration obtained beforehand and the membrane blockage degree evaluation index, the membrane blockage degree evaluation index is obtained from the nanoparticle number concentration obtained by the nanoparticle number concentration measuring means, and the membrane of the water to be treated Membrane treatment equipment that can evaluate occlusive properties and select operating conditions. A method of operating a membrane treatment apparatus for treating filtered water using a separation membrane to obtain filtered water,
A nanoparticle number concentration measuring step for measuring the nanoparticle number concentration of the water to be treated;
Based on the relationship between the nanoparticle number concentration and the membrane blockage degree evaluation index obtained in advance, the membrane occlusion degree evaluation index is obtained from the nanoparticle number concentration obtained by the nanoparticle number concentration measurement step, and the membrane of the water to be treated An operation condition selection step for evaluating the blockage and selecting the operation condition;
A method for operating a membrane treatment apparatus.