JP7074507B2 - Pollution risk assessment method for water treatment system - Google Patents

Description

The present invention relates to a pollution risk assessment method for a water treatment system using an organic substance identification method in treated raw water by a fluorescence method.

Water treatment systems using ion exchange resins use industrial water as raw water, and industrial water originating from river water and lake water contains sugars, proteins, and organic substances derived from soil. It is generally known that soil-derived organic matter has different compositions depending on the region, and is collectively called humic acid. Fumin is a final decomposition product when plants and the like are decomposed by microorganisms, and is a persistent polymer compound consisting of a linear hydrocarbon and a polycyclic aromatic compound (molecular weight of about 100,000 to 100,000). It has the same brown humic acid and fulvic acid as the soil and is also called humus. Most of humic acid can be removed by a general treatment method such as coagulation precipitation and rapid filtration, but fulvic acid and the like cannot be removed. Humic acid is insoluble in acid, but fulvic acid is soluble in acid, has many COOH groups and OH groups, is highly hydrophilic, and has a small molecular weight. Therefore, sugars, proteins, and humic acid can be removed by normal pretreatment (aggregation, pH adjustment, filtration, etc.), and organic acids and small molecules other than fulvic acid adhere to the ion exchange resin. However, it can be easily peeled off and removed by a normal regeneration operation. On the other hand, an adsorption tower using activated carbon can be placed in front of the resin tower filled with ion exchange resin to remove all organic substances containing fulvic acid, but if the adsorption capacity is exceeded, deflowering will occur and the organic substances will exchange ions. It flows into the resin tower filled with resin. Therefore, it is important to understand the organic matter in the treated raw water.

The amount of organic matter in raw water and the ability of the adsorption tower to remove organic matter using activated charcoal are generally controlled by the total organic carbon concentration in water (hereinafter referred to as TOC concentration), but in TOC concentration control, the classification of organic matter is performed. Cannot be carried out, and it cannot be evaluated whether it is an organic substance that may reduce the performance of the ion exchange resin.

Patent Document 1 discloses an evaluation method for evaluating the quality of the supply water supplied to the ion exchange device, and a method for managing the operation of the ion exchange device based on this evaluation method. As this evaluation method, an organic matter evaluation method by an organic carbon detection type size exclusion chromatograph method (LC-OCD) has been proposed, and it is said that only fulvic acid can be analyzed by combining with qualitative analysis.

JP-A-2015-226866

The 3D-EEM measurement in Patent Document 1 is just a qualitative analysis. That is, as a result of qualitative analysis, it is confirmed that there is no compound having a molecular weight equivalent to that of fulvic acid, and evaluation is performed by LC-OCD.

In the evaluation by LC-OCD, as described above, organic substances, particularly humic acid and fulvic acid, cannot be evaluated because they cannot be fractionated. Furthermore, humus such as fulvic acid is possible only when other components of equivalent molecular weight are not present in combination with fluorescence analysis. Furthermore, LC-OCD analysis takes nearly 100 minutes.

In addition, the composition of organic components contained in the treated raw water differs depending on the region and season, and if water containing a large amount of fulvic acid is passed without activated carbon treatment, the risk of contamination of the anion exchange resin increases. On the contrary, if the amount of humic acid is larger and the amount of fulvic acid is smaller, it is possible to sufficiently remove organic matter by treatment such as aggregation in the previous stage, and it may be possible to extend the regeneration or replacement period of activated carbon in the adsorption tower. ..

In this way, by constructing a water treatment system that matches the treated raw water, unnecessary pre-treatment can be eliminated or reduced to reduce the system cost, and the necessary chemicals can be injected or activated carbon in the adsorption tower can be regenerated. Understanding the replacement time is technically extremely significant.

Therefore, in the present invention, an organic matter identification method capable of grasping organic matter in raw water and a risk evaluation method of a water treatment system to which the identification method is applied for organic matter in raw water in a water treatment system, particularly problematic humus, etc. The purpose is to provide.

The present invention provides a method for measuring organic substances in treated raw water in a water treatment system by a fluorometric method and fractionating them in a soft manner.

That is, according to one aspect of the present invention.
It is a pollution risk assessment method for water treatment systems using ion exchange resins.
The process of measuring raw water by the three-dimensional fluorometric method and obtaining fluorescence intensity data including the peak of fuminic substance, and
A step of separating the obtained fluorescence intensity data into a plurality of components by PARAFAC analysis, and
A step of principal component analysis of the score value of each separated component, and
From the results of the principal component analysis, plot the eigenvector values of the first principal component and the second principal component on the XY plane with the first principal component as the X axis and the second principal component as the Y axis, and plot the eigenvector values. The process of grasping the fractionation and amount of components based on the direction of the point and the distance from the reference point,
At least the components of fumic acid and fulboic acid are fractionated and grasped by using the organic substance identification method having the above, and the risk of contamination of the ion exchange resin by the organic substance in the water treatment system is predicted. Provided is a method for assessing the pollution risk of a water treatment system, which comprises changing the treatment means and the treatment method according to the raw water.

According to the present invention, by measuring the fluorescence intensity of a specific organic substance by a fluorometric method that can be measured in an extremely short time and treating it in two steps in a soft manner, it is possible to fractionate organic components that are normally difficult to fractionate. It becomes.
As a result, the risk of organic matter contamination in the water treatment system can be predicted, a system suitable for the raw water to be used can be constructed, and the timing of maintenance of the activated carbon tower and the like can be predicted.

It is a spectrum figure which shows an example of 3D-EEM. It is a spectrum diagram separated into three components. It is a figure which plotted the data after PCA processing. It is a flowchart of the organic substance identification method of this invention. It is the figure which plotted the raw water data by prefecture. It is a flow figure which shows the outline of the water treatment system to which this invention is applied.

In the three-dimensional fluorescence photometric method (3D-EEM), the object to be measured is irradiated with light having an excitation wavelength, and the fluorescence wavelength and fluorescence intensity emitted by the compound are measured with respect to the excitation wavelength. In the present invention, a sample of treated raw water is placed in a transparent cell.

When water containing soil-degradable organic substances was measured by the fluorescence photometric method, the soil-derived fuminate had an excitation wavelength of 305-330 nm / fluorescence wavelength of 415-435 nm and an excitation wavelength of 255-275 nm / fluorescence wavelength of 440-455 nm. Two peaks can be seen. In the literature, the former is humic acid and the latter is fulvic acid, but in reality, it is widely distributed within the fluorescence wavelength of 370-480 nm at the excitation wavelength of 200-380 nm, and the peak position changes depending on the location and origin. do. Also, due to the overlap of peaks in the skirts, the peak position of one peak is often unclear due to the skirts of the other peak.

FIG. 1 is a diagram showing the fluorescence intensity when the treated raw water is measured by the three-dimensional fluorometric method, with the fluorescence wavelength on the horizontal axis and the excitation wavelength on the vertical axis, and the intensity shown by contour lines. Here, two peaks, one strong peak and one weak peak, are observed near the fluorescence wavelength of 420 nm. The two spindle-shaped regions are scattered light and secondary light.

The three-dimensional fluorescence intensity was measured under the following conditions.
Measuring equipment: Spectral fluorometer F-7000 (manufactured by Hitachi)
Measurement conditions: Excitation start wavelength 200 nm
Excitation end wavelength 600 nm
Fluorescence start wavelength 200 nm
Fluorescence end wavelength 600 nm
Scan speed 60,000 nm / min
Excited side slit 10.0 nm
Fluorescent side slit 10.0 nm
Photomal voltage 400V

Next, the scattered light of the excitation light and the secondary light thereof, which are noise information, are deleted, and the peak in which the strong fluorescence intensity is detected is extracted from the plurality of fluorescence wavelength peaks, and peak separation and correction processing are performed. This process is called PARAFAC analysis (Parallel Factor Analysis; Hitchcock, 1927; Carrol and Chang, 1970; Harshman, 1970) after text-processing the measured data, and decomposes the multidimensional array to focus on the desired features. And do it by a statistical method that clearly explains the results. Actually, this PARAFAC analysis is performed using "Solo" manufactured by MATLAB as analysis software. In the present invention, as shown in FIG. 2, the peak is separated into three components 1 to 3. The number of components to be separated is not particularly limited, and the number of components to be separated is an appropriate number. Whether or not the number of divided components is a reasonable number can be determined by whether or not the value of Core consistency is close to 100%.

Next, a principal component analysis (PCA) is performed. This is a method of calculating principal components based on multi-wavelength fluorescence intensity data (explanatory variables) by multivariate analysis and grouping them. For this grouping, statistical software JMP (SAS Institute Japan Co., Ltd.) is used as analysis software, and principal component analysis is performed on the score values of components 1 to 3 obtained by PARAFAC analysis. Component 1 of PARAFAC is a score value derived from fulvic acid, component 2 is derived from protein, and component 3 is a score value derived from humic acid. When this is analyzed, for example, an eigenvector as shown in Table 1 below can be obtained. The origin of components 1 to 3 is determined based on their fluorescence wavelength and excitation wavelength.
Here, the score value is a numerical value obtained by considering the overlap of peaks in the intensity of fluorescence intensity of component 1, component 2, and component 3 contained in the sample.

The first main component is in the + direction when all of fulvic acid, humic acid, and protein are abundant, the second main component is in the + direction when there is a lot of fulvic acid, in the-direction when there is a lot of humic acid, and in the + direction when there is a lot of protein. It becomes.

FIG. 3A shows data after PCA treatment for various treated raw waters such as industrial water, groundwater, river water, lake water, tap water, etc. used in the water treatment system, and the first main component (PC1) is X. It is a figure which plotted the axis (horizontal axis) and the second principal component (PC2) as a Y axis (vertical axis). The contribution rates of PC1 and PC2 were 63.5% and 36.5%, respectively, for a total of 100%. In each case, the farther away from the reference point X, Y = 0, 0, the larger the amount of the component. FIG. 3B is a diagram showing a vector of each component from the result of FIG. 3A.
The contribution rate indicates how much the data is scattered over the entire data. The contribution rate of PC1 is the value obtained by dividing the variance (eigenvalue) p1 of the first principal component by the eigenvalue p of all the data. Since there are three components this time, the dispersion p1 of PC1, the dispersion p2 of PC2, and the dispersion p3 of PC3 are p = p1 + p2 + p3. In the present invention, since PC1 is plotted on the XY plane with PC1 as the X-axis and PC2 as the Y-axis for evaluation, it can be said that the closer the total contribution ratio of both is to 100%, the more the original data can be sufficiently expressed. ..

FIG. 4 shows a flow chart of data processing according to the present invention.
S1 is a step (3D-EEM measurement of treated raw water) of measuring raw water by a three-dimensional fluorometric method and obtaining fluorescence intensity including a peak of a target organic substance.
S2 is a step (component separation) of separating the obtained fluorescence intensity peak into a plurality of components by PARAFAC analysis.
S3 is a step of principal component analysis of the score value of each separated component.
S4 is a step of plotting the eigenvector values of the first principal component and the second principal component from the results of the principal component analysis on an XY plane having the first principal component as the X axis and the second principal component as the Y axis. (Plot step), and S5 is a step of grasping the fractionation and the amount of the components from the direction of the plot point and the distance from the reference point.
S6 is a step of grasping the contamination risk of the ion exchange resin in the water treatment system from the distribution area of the target sample on the XY plane.
The steps S2 to S6 can be performed using a computer.

The process of S6 will be described in more detail.
FIG. 5 shows the results of classifying industrial water, well water, and river water by region (by prefecture). In this case, the contribution rates of PC1 and PC2 were 62.6% and 37.4%, respectively. In this case as well, the total contribution rate is 100%, which indicates that the original data is sufficiently expressed. Further, the vectors of the fulvic acid-derived component, the humic acid-derived component, and the protein-derived component are also slightly different from those in FIG.

As shown in FIG. 5, the region AR1 having a large amount of fluboic acid-derived components shows that the risk of contamination of the anion exchange resin is high in the water treatment system using the ion exchange resin. That is, sufficient activated carbon treatment is required, and care must be taken in the replacement or regeneration of activated carbon in the activated carbon tower. On the other hand, in the region AR2 in which the amount of fulvic acid-derived components is small and the amount of humic acid-derived components is large, humic acid can be aggregated by the aggregation treatment in the previous stage, and the risk of contamination of the anion exchange resin is slightly reduced. In the case of the region AR3 close to X, Y = 0,0, the organic matter itself is small, and the risk of contamination of the anion exchange resin is considerably low. It is possible to eliminate the coagulation treatment in the previous stage and use activated carbon treatment, and the frequency of replacement or regeneration of activated carbon in the activated carbon tower is reduced.

As described above, in the present invention, it is possible to grasp the main components of the organic matter in the treated raw water, and it is possible to construct a water treatment system and select an operation method thereof according to the main components.

FIG. 6 is a flow chart illustrating an outline of the water treatment system according to the present invention. Here, an example of a pure water production system will be described, but the present invention is not limited to this, and can be applied to various water treatment systems.

As shown in FIG. 6, first, raw water such as industrial water is roughly filtered by the sand filtration device 10. The sand filtration device 10 is not essential and is provided as needed. The organic matter contained in the water to be treated after filtration is subjected to a coagulation treatment by the coagulation treatment tank 20, and subsequently adsorbed by the adsorption tower 30 using activated carbon. After that, the cation species contained in the water to be treated are removed in the cation tower 40 filled with the cation exchange resin. The treated water that has passed through the cation tower 40 is further treated by the anion tower 60 filled with the next anion exchange resin, but before that, the carbonic acid that affects the anion exchange resin is removed by the decarbonation tower 50. In the coagulation treatment tank 20, treatments such as coagulation filtration, coagulation precipitation, and coagulation pressure levitation are performed. Since humic acid is insoluble in acid, it is acidified and aggregated with PAC or iron chloride.

The raw water sample is sent from the intake port 2 (or from the intake port 12 of the water to be treated after filtration if there is a sand filtration device 10) to the 3D-EEM measuring device 1, and the S1 step shown in FIG. 4 is carried out. do. The 3D-EEM measurement data 3, for example, text data in CSV format is sent to the computer 4, and the steps S2 to S6 shown in FIG. 4 are carried out. Each of the 3D-EEM measuring device 1 and the computer 4 may be installed at the site where the pure water production system is installed, or may be installed at a remote location. The computer 4 can take in data of various regions via the Internet or the like.

Further, in the present invention, when predicting the contamination risk of an unknown sample, PARAFAC analysis and main component analysis are performed by combining the 3D-EEM measurement data of the unknown sample with the 3D-EEM measurement data based on a plurality of known samples. Therefore, the risk of contamination of the ion exchange resin by organic substances can be predicted only by 3D-EEM measurement. When predicting the pollution risk, it is preferable to make a comprehensive evaluation in consideration of the carbon content (TOC) of the raw water and the result of LC-OCD. That is, it is possible to predict the contamination risk of the unknown sample by comparing it with the contamination risk of the known sample from the direction of the plot point on the XY plane of the unknown sample and the distance from the reference point.

In the present invention, the organic matter in the treated raw water is grasped by the above-mentioned organic matter identification method, the risk of contamination of the ion exchange resin by the organic matter in the water treatment system is predicted, and the treatment means and the treatment method in the first stage of the ion exchange resin in the water treatment system are used. Change according to the raw water. As a result, the presence or absence of the coagulation treatment tank 20 and the exchange / regeneration frequency of the activated carbon in the activated carbon tower 30 can be controlled to reduce the risk of contamination of the organic matter of the ion exchange resin. Note that [] in FIG. 6 indicates that the configuration is arbitrary.

1 3D-EEM measuring device 2, 12 Intake port 3 Data 4 Computer 10 Sand filtration device 20 Coagulation treatment tank 30 Adsorption tower containing activated carbon 40 Cation tower 50 Decarbonization tower 60 Anion tower

Claims (5)

It is a pollution risk assessment method for water treatment systems using ion exchange resins.
The process of measuring raw water by the three-dimensional fluorometric method and obtaining fluorescence intensity data including the peak of fuminic substance, and
A step of separating the obtained fluorescence intensity data into a plurality of components by PARAFAC analysis, and
A step of principal component analysis of the score value of each separated component, and
From the results of the principal component analysis, plot the eigenvector values of the first principal component and the second principal component on the XY plane with the first principal component as the X axis and the second principal component as the Y axis, and plot the eigenvector values. The process of grasping the fractionation and amount of components based on the direction of the point and the distance from the reference point,
At least the components of fumic acid and fulboic acid are fractionated and grasped by using the organic substance identification method having the above, and the risk of contamination of the ion exchange resin by the organic substance in the water treatment system is predicted. A method for assessing a pollution risk of a water treatment system, which comprises changing a treatment means and a treatment method according to the raw water. The contamination of the water treatment system according to claim 1, wherein the step of separating into a plurality of components by PARAFAC analysis is a step of separating into three components, a humic acid-derived component, a fulvic acid-derived component, and a protein-derived component. Risk assessment method. The pollution risk assessment method for a water treatment system according to claim 1 or 2, wherein the excitation wavelength in the three-dimensional fluorometric method is 200 to 600 nm. By performing PARAFAC analysis and main component analysis by combining the fluorescence intensity data of the unknown sample with the fluorescence intensity data of a plurality of known samples, the direction of the plot point and the distance from the reference point of the unknown sample in the XY plane. The method for assessing the pollution risk of a water treatment system according to any one of claims 1 to 3, wherein the risk of contamination of an unknown sample is predicted by comparing with the risk of contamination of a known sample. The treatment means and the treatment method in the first stage of the ion exchange resin include at least one of a method of acidifying raw water to remove humic acid by agglomeration treatment and a means of adsorbing and removing organic substances from raw water by activated carbon treatment. The method for assessing the pollution risk of the water treatment system according to any one of 4.

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