JP2003075348A - Method and instrument for measuring water quality - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contactlessly measure an index of water quality, for example, an anion surfactant (LAS and the like) in sample water, in particular, sulfonic acid type anion surfactant, and a BOD, as to the sample water such as river water and lucastrine water, without contact and a reagent, and to cope with continuous measurement. SOLUTION: At least two ultraviolet rays different in wavelengths is made to get incident, fluorescence intensity of a specified wavelength emitted from the sample water by the each wavelength of ultraviolet ray is measured, and a specified water quality index quantity of the sample water is measured based on fluorescence intensity information of the specified wavelength in the each wavelength of ultraviolet ray.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention can measure water quality indicators such as anionic surfactants and BOD in sample water such as river water and lake water in a non-contact and reagentless manner, and further in continuous measurement. The present invention relates to a water quality measuring method and device corresponding to.

[0002]

2. Description of the Related Art In recent years, with increasing interest in environmental protection, in order to prevent water pollution of river water, lake water, etc.,
It is very important to monitor the water quality.

For example, there are various causes for causing water pollution of river water and lake water such as domestic wastewater and industrial wastewater. However, as a water quality index for judging the degree of pollution and establishing regulations and standards, There is a surfactant, BOD (biochemical oxygen consumption (demand) amount).

As a surfactant, most of the synthetic detergents used at home are anionic surfactants, and it has been pointed out that the anionic surfactant has an effect on the environment. Therefore, it is meaningful to quantify the anionic surfactant in order to evaluate the amount of the anionic surfactant in river water or lake water, or the removal rate of the anionic surfactant in the sewage treatment facility.

Conventionally, the methylene blue absorptiometry is generally used as a method for measuring an anionic surfactant. The method is based on Japanese Industrial Standards (JIS K 0102, 30.
The ion pair generated by the reaction of the anionic surfactant with methylene blue [3,7-bis (dimethylamino) phenothiazine-5-ium chloride] specified in 1) is extracted with chloroform, and the absorbance at a wavelength of about 650 nm is determined. By measuring, the anionic surfactant is quantified as a methylene blue active substance.

In particular, in order to quantify sulfonic acid type anionic surfactants such as linear alkylbenzene sulfonates (LAS), which is the mainstream of anionic surfactants, by the methylene blue absorptiometric method, the pretreatment is carried out in sample water. It is necessary to hydrolyze anionic surfactants such as alcohols.

On the other hand, as a method of measuring BOD, which is widely used as a water quality index, the Japanese Industrial Standard (JIS
21 of K 0102. The standard dilution method specified in 1) is common. In this method, the sample water is diluted with water, and
When left at 5 ° C for 5 days, BOD is represented by the amount of dissolved oxygen consumed by aerobic microorganisms in water (BOD ₅ value).
It is necessary to add a certain amount of nutrient salts to the dilution water and to inoculate an appropriate microorganism when the sample water contains few microorganisms.

[0008]

However, there are the following problems in the measurement of the above-mentioned conventional anionic surfactant and BOD.

The methylene blue absorptiometry requires many reagents such as methylene blue solution, chloroform, acid and alkali. Further, for example, it is necessary to repeat the extraction operation in order to completely remove water from the organic solvent layer, which involves complicated operation for measurement and takes time,
It also requires considerable skill. Moreover, there is a problem that the waste liquid of the organic solvent remains in the end.

In particular, in order to measure a sulfonic acid type anionic surfactant (such as LAS) by the methylene blue absorption spectrophotometry, the sample water is hydrolyzed as described above, and then the target substance is extracted with an organic solvent, You have to take measurements
Furthermore, the operation becomes complicated and the number of reagents used increases.

As described above, the methylene blue absorptiometry generally used cannot perform non-contact and reagentless measurement, and is not a method capable of continuous measurement.

EL capable of quantifying anionic surfactants
ISA (enzyme immunoassay) kit (Takeda Pharmaceutical Co., Ltd.)
Manufactured by Metrohm Co., Ltd., and a surfactant titrator (potentiometric titration). However, all of them are devices for laboratories and are not for continuous measurement, and require special reagents. In the above-mentioned surfactant titrator, there is an electrode that can be measured without extracting the object from the sample water, but a dedicated reagent is still required at the time of titration.

On the other hand, the BOD measurement by the standard dilution method is as follows.
It takes 5 days from the start of measurement to the end. In addition, since there is a range of dissolved oxygen amount for obtaining an appropriate BOD measurement value, in the case of sample water that requires dilution, the dilution rate is determined from the results after 5 days, and then the measurement is performed for another 5 days. It is necessary and very time consuming. Although it is possible to predict the dilution rate of the sample water in advance, considerable skill is required to predict an appropriate dilution rate.

Further, the standard dilution method requires a large number of reagents, and operations such as pretreatment of these reagents, dilution water and seed dilution water are extremely complicated. The measured value depends on the added reagent, the type of planting, and the concentration, and it cannot be judged without waiting for the result after 5 days. Furthermore, since the planted species are microorganisms, it is difficult to constantly maintain constant attributes, activities, and concentrations.

As described above, in the BOD measurement by the standard dilution method, non-contact and reagent-free measurement cannot be performed,
Moreover, it cannot be applied to continuous measurement.

Various proposals have been made for the purpose of simplifying the measurement of BOD. For example, a BOD measuring device [DKK that measures oxygen consumption for 5 days by a manometer method]
Co., Ltd. (now Toa DKK Co., Ltd.) BOD-3]. In addition, as a measuring method utilizing optical analysis, a method of measuring dissolved oxygen before and after culture using a fluorescent oxygen sensor (Japanese Patent Laid-Open No. 11-242025), luminescence by assimilation of an organic substance by a luminescent gene-introduced luminescent bacterium A method of measuring the amount (Japanese Patent Laid-Open No. 9-56397) and a method of obtaining the BOD from the correlation with the ultraviolet absorbance (Japanese Patent Laid-Open No. 1910-9)
15).

However, the method of measuring oxygen consumption by the manometer and the method of using the fluorescent oxygen sensor still require 5 days of culture. or,
A constant incubation period is required even in the method using the above-mentioned luminescent bacteria. Therefore, none of the methods solves the problem of determining the dilution rate of the sample water as described above, and does not support continuous measurement. Furthermore, in the method using the luminescent bacterium, preparation, maintenance, and pretreatment of the luminescent bacterium by transduction involve complicated operations, not only many reagents are required, but also continuous measurement cannot be realized. .

In addition, in the method based on the above-mentioned ultraviolet absorption, organic matter generally absorbs light in the ultraviolet region, so that when a large amount of organic matter is present in the sample water and the water quality is a specific water quality that does not change. It may be effective, but it is considered unsuitable when the water quality varies greatly depending on the water system, such as sample water with large fluctuations in the amount of organic matter, river water, and lake water.

By the way, conventionally, fluorescence analysis has been used in microanalysis such as liquid chromatography. Fluorescence analysis has the advantage that it can measure low concentrations if the target component can be separated and specified. However, these are generally for laboratory use, and there are hardly any examples of non-contact, reagentless continuous measurement of an object using the ultraviolet fluorescence method.

Under these circumstances, a report has been made suggesting the possibility of BOD measurement by the ultraviolet fluorescence method. Reynolds et al. (Wat. Res. Vol. 31, No. 8, pp. 2012-2018, 1997)
Reported a linear correlation between the fluorescence intensity (excitation wavelength: 280 nm) of wavelength 340 nm emitted by the treated water in the sewage treatment facility and BOD ₅ , suggesting the possibility of monitoring the BOD of the treated water.

In addition, Amado et al. (Wat. Res. Vol. 33, No.
9, pp. 2069-2074, 1999) has a wavelength of about 350 due to the contribution of the biodegradable fluorescent component in the treated water in the sewage treatment plant.
Fluorescence intensity at nm (excitation wavelength 240 nm to 300 n
m) and BOD ₅ are reported to be linear, suggesting the possibility of monitoring the BOD of the treated water using the ultraviolet fluorescence method.

However, in river water, lake water, and the like, which have different water qualities depending on the water system, the fluorescence emitted by being excited by ultraviolet rays greatly differs depending on the sampling location. Therefore, according to the study by the present inventor, with respect to sample water such as river water and lake water having different water qualities, water quality indicators such as anionic surfactant and BOD are measured by non-contact and no reagent by the ultraviolet fluorescence method. However, when attempting continuous measurement, it became clear that a calibration curve was required for each sample water, such as blank measurement and correction.

Therefore, an object of the present invention is generally to provide a water quality index for sample water such as river water and lake water, for example, an anionic surfactant in the sample water, especially a sulfonic acid type anionic surfactant (LAS). Etc.) and BOD can be measured in a non-contact and reagentless manner, and a water quality measuring method and device capable of supporting continuous measurement are provided.

Another object of the present invention is to predict the BOD of sample water such as river water and lake water, which is also used as an index of the dilution ratio of sample water when measuring BOD by the standard dilution method. An object of the present invention is to provide a water quality measuring method and device capable of performing the above.

Another object of the present invention is that a calibration curve can be easily prepared with a simple structure, and the anionic surfactant in the sample water is always stable, especially the sulfonic acid type anionic surfactant (LAS). Etc.), BOD can be measured in a non-contact and reagentless manner, and a water quality measuring method and device capable of supporting continuous measurement are provided.

[0026]

The above object can be achieved by a water quality measuring method and apparatus according to the present invention. In summary, the first aspect of the present invention is to irradiate a sample water with at least two ultraviolet rays having different wavelengths, measure the fluorescence intensity of a specific wavelength emitted from the sample water by the ultraviolet rays of each wavelength, It is a water quality measuring method characterized in that a specific water quality index amount of sample water is measured based on fluorescence intensity information of a wavelength. According to one embodiment of the present invention, the specific water quality index amount is the amount of linear alkylbenzene sulfonates in the sample water. Further, according to another embodiment of the present invention, the specific water quality index amount is a biochemical oxygen demand amount of the sample water.

According to the second aspect of the present invention, the sample water is irradiated with ultraviolet rays of two different wavelengths, and the fluorescence intensity of the specific wavelength emitted by the sample water is measured by the ultraviolet rays of the respective wavelengths. A method for measuring water quality is provided, in which the amount of linear alkylbenzene sulfonates in sample water is measured by determining the difference in fluorescence intensity. According to one embodiment of the present invention, the two different wavelengths of the ultraviolet light have center wavelengths of 210 nm and 230 nm, respectively.
The center wavelength of the specific wavelength is 290 nm.

According to the third aspect of the present invention, the sample water is irradiated with ultraviolet rays of two different wavelengths, and the fluorescence intensity of the specific wavelength emitted by the sample water is measured by the ultraviolet rays of the respective wavelengths. There is provided a water quality measuring method characterized in that the biochemical oxygen demand of the sample water is measured by determining the difference in fluorescence intensity of the water. According to one embodiment of the present invention, the difference in the fluorescence intensity of the specific wavelength with respect to the ultraviolet light of each wavelength, from the fluorescence intensity of the specific wavelength with respect to the ultraviolet light of at least one wavelength, when the pure water is irradiated with ultraviolet light of the wavelength. It is determined by using the fluorescence intensity obtained by subtracting the fluorescence intensity of the specific wavelength emitted in. In addition, according to another embodiment of the present invention, the ultraviolet rays having two different wavelengths have central wavelengths of 210 nm and 230 nm, respectively, and the specific wavelength has a central wavelength of 420 nm.

According to the fourth aspect of the present invention, the sample water containing section to which the sample water is supplied, and the projecting section for irradiating the sample water in the sample water containing section with at least two ultraviolet rays having different wavelengths,
Fluorescence detection unit for detecting the fluorescence of a specific wavelength emitted by the sample water by ultraviolet rays of each wavelength, and the sample water based on the signal emitted by the fluorescence detection unit according to the fluorescence intensity of the specific wavelength for the detected ultraviolet rays of each wavelength There is provided a water quality measuring device comprising: a calculation unit that calculates a specific water quality index amount. According to one embodiment of the present invention, the calculating means obtains a difference in fluorescence intensity of the specific wavelength with respect to ultraviolet rays of each wavelength based on a signal from the fluorescence detecting unit, thereby obtaining a specific water quality index amount of sample water. To measure. According to another embodiment of the present invention, further has a storage means for storing information indicating the correlation between the difference in fluorescence intensity of the specific wavelength with respect to ultraviolet rays of each wavelength and the specific water quality index amount of the sample water in advance, The calculation means, the difference in the fluorescence intensity of the specific wavelength with respect to the ultraviolet rays of each wavelength obtained based on the signal from the fluorescence detection unit, information stored in advance in the storage means,
Based on the above, a specific water quality index amount of the sample water is measured. In one embodiment of the present invention, the sample water is continuously supplied to the sample water container, and the specific water quality index amount of the sample water is continuously measured. Further, in one embodiment of the present invention, the specific water quality index amount is a linear alkylbenzene sulfonate in the sample water, and the projecting unit irradiates the sample water with ultraviolet rays having central wavelengths of 210 nm and 230 nm, respectively. The fluorescence detection unit can detect fluorescence having a central wavelength of 290 nm. Further, in another embodiment of the present invention, the specific water quality index amount is a biochemical oxygen demand amount of sample water, and each of the light projecting units has a center wavelength of 210 n.
By irradiating the sample water with ultraviolet rays having a wavelength of 230 nm, the fluorescence detection unit can detect fluorescence having a center wavelength of 420 nm.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a water quality measuring method and apparatus according to the present invention will be described in more detail with reference to the drawings.

Example 1 (Measurement of Anionic Surfactant) In this example, the water quality measuring method of the present invention was used to measure linear alkylbenzene sulfonates (LAS) which are anionic surfactants as a water quality index. The case of application will be described.

First, LAS with various LAS concentrations changed
Obtain fluorescence spectra of standard solutions at various excitation wavelengths
The relationship between the AS concentration and the fluorescence intensity of sample water was examined.

Test Example 1 LAS (manufactured by Wako Pure Chemical Industries, Ltd .:
Linear alkylbenzene sulfonic acid) diluted with pure water L
AS standard solution (concentration 0.08 mg / L to 3.08 mg /
L) was loaded into a fluorescence detector (manufactured by JASCO Corporation: model number FP-920) with a flow rate of 1 ml by a peristaltic pump.
/ Nm, and the excitation wavelength is changed (200 nm
˜460 nm) fluorescence spectra were obtained respectively.

As a result, excitation wavelengths of 210 nm and 230n
In m, it was found that the fluorescence intensity of the LAS standard solution at a wavelength of 290 nm changes in proportion to the LAS concentration.

FIG. 1 shows excitation wavelengths of 210 nm and 230 nm.
2 shows a fluorescence spectrum of the LAS standard solution according to. The fluorescence intensity at a wavelength of 290 nm was read from each fluorescence spectrum at the excitation wavelengths of 210 nm and 230 nm, and
As shown in, a calibration curve (calibration curves I and II, respectively) showing the relationship between the fluorescence intensity and the LAS concentration was prepared.

From FIG. 2, approximately 0.1 mg / L to 3 mg /
It can be seen that in the range of L, the relationship between the LAS concentration and the fluorescence intensity of the LAS standard solution at the wavelength of 290 nm at the excitation wavelengths of 210 nm and 230 nm has a substantially linear correlation.

From this result, in principle, 210 nm or 230 nm is used as the excitation wavelength, the fluorescence intensity of 290 nm is measured as the detection wavelength, and the calibration curves I and II at the respective excitation wavelengths are used to obtain the sample water. LAS
It is considered possible to quantify.

However, further studies by the present inventor have revealed the following. That is, river water, lake water, and the like have different water qualities depending on the water system, and the fluorescence emitted by being excited by ultraviolet rays greatly differs depending on each sample water (water sampling place).

Generally, when LAS is added to each of river water and lake water at different sampling locations, the excitation wavelength is 210 n.
The fluorescence spectrum at m and 230 nm is LA in pure water.
The blank becomes higher than that of the LAS standard solution containing S, and the blank has variations in each sample water.

Therefore, for various sample water such as river water and lake water having different water qualities, 210 nm, 2
290nm wavelength by any one excitation wavelength of 30nm
0.2 mg of the LAS concentration measured value by using the calibration curve I or the calibration curve II.
It was impossible to measure a low concentration below / L.

Based on such new knowledge, the inventor diligently studied and found the difference between the fluorescence intensity of 290 nm wavelength by the excitation wavelength of 230 nm and the fluorescence intensity of 290 nm wavelength by the excitation wavelength of 210 nm, and correlated it with the LAS concentration. It was found that by using as a calibration curve III, even when the blank changes due to sample water having different water qualities, the influence can be reduced or eliminated.

That is, according to the study by the present inventor, pure water,
Tap water (LAS 0 mg / L) has two excitation wavelengths of 2
It was found that there was no difference in fluorescence intensity at a wavelength of 290 nm at 10 nm and 230 nm. Also, when the LAS standard reagent is added to pure water, two excitation wavelengths of 210 nm,
The difference in the fluorescence intensity at a wavelength of 290 nm due to 230 nm is L
Proportional to AS concentration. Furthermore, the calibration curve III is LA
LA of sample water (LAS standard solution) in which S standard is added to pure water
It was found to be more accurate than the calibration curves I and II, even for S concentration measurements.

Two excitation wavelengths 210n are shown in Table 1 and FIG.
Wavelength 2 of LAS standard solution at m and 230 nm, respectively
The relationship (calibration curve III) between the difference in fluorescence intensity at 90 nm and the LAS concentration is shown. Incidentally, in FIG. 2, the correlation coefficient (R
² ) is shown.

[0044]

[Table 1]

From FIG. 2, it can be seen that the calibration curve III shows a very good linear correlation. By using this calibration curve III, it is possible to remarkably reduce or eliminate the influence of the blank even for sample water having greatly different water quality (blank).

The LAS concentration measuring method of this embodiment will be further described below with reference to some test examples. In the following test examples, the fluorescence detector and the measuring method are the same as those in the above-mentioned test example 1.

(Test Example 2) Commercially available neutral detergent (Kaneyo Soap Co., Ltd .: trade name "Sopun", main component LAS 18%)
Was diluted with pure water to obtain fluorescence spectra at excitation wavelengths of 210 nm and 230 nm. As a result, similar to the LAS standard solution in Test Example 1, at each excitation wavelength,
A peak proportional to the added amount of the neutral detergent was detected at a wavelength of 290 nm.

Fluorescence intensity at a wavelength of 290 nm at each excitation wavelength was read from the obtained fluorescence spectrum, and LAS concentration measurement values were obtained from the three calibration curves I, II, and III prepared in Test Example 1. The results are shown in Table 2.
The relationship between the amount of LAS added from the neutral detergent and the measured value is shown in FIG. Here, the amount of LAS added from the neutral detergent was obtained from the content and the dilution rate described on the label of the neutral detergent.

[0049]

[Table 2]

As can be seen from FIG. 3, the LAS concentration measured value obtained from the calibration curve I is below 1 mg / L.
On the other hand, the LAS concentration measured value obtained from the calibration curve III is 1
Even at mg / L or less, the line is excellent.

(Test Example 3) River water (Tokyo: Asakawa, 12
A LAS standard reagent of known concentration was added to (monthly water), and fluorescence spectra were obtained at excitation wavelengths of 210 nm and 230 nm, respectively. As a result, similarly to the LAS standard solution in Test Example 1, at each excitation wavelength, a peak was detected at a wavelength of 290 nm that was proportional to the amount of the neutral detergent added.

Fluorescence intensity at a wavelength of 290 nm at each excitation wavelength was read from the obtained fluorescence spectrum, and LAS concentration measurement values were obtained from the three calibration curves I, II, and III prepared in Test Example 1. The results are shown in Table 3.
The relationship between the amount of LAS standard reagent added and the measured value is shown in FIG.

[0053]

[Table 3]

(Test Example 4) River water (Tokyo: Asakawa, 12
Monthly sampling), lake water (Nagano Prefecture: Lake Kamahara, November sampling)
Add a commercially available neutral detergent (same as above) and excite wavelength 210n
m and 230 nm fluorescence spectra were obtained. As a result, similar to the LAS standard solution in Test Example 1,
At each excitation wavelength, a peak proportional to the amount of the neutral detergent added was detected at a wavelength of 290 nm.

Fluorescence intensity at a wavelength of 290 nm at each excitation wavelength was read from the obtained fluorescence spectrum, and LAS concentration measurement values were obtained from the three calibration curves I, II, and III prepared in Test Example 1. The results are shown in Table 4.
5 and 6 show the relationship between the amount of LAS added from the neutral detergent and the measured value for each sample water. The addition amount was calculated from the content and the dilution rate shown on the label of the neutral detergent.

[0056]

[Table 4]

In Test Example 3 and Test Example 4, a calibration curve I,
It can be seen that the LAS concentration measurement values obtained from the calibration curve II have variations, and that values below 0.5 mg / L have no reliability. In particular, the LAS concentration measured value obtained from the calibration curve I has variations.

On the other hand, L obtained from the calibration curve III
As the measured AS concentration value, a value proportional to the amount of LAS (LAS standard reagent, LAS from neutral detergent) added was obtained, and it can be seen that the reliability is high.

From the above Test Examples 1 to 4, the excitation wavelength 210
nm, by using the difference in fluorescence intensity at a wavelength of 290 nm of sample water by 230 nm, 0.05 mg /
It was found that measurement is possible within the range of L to 3 mg / L.

In the results shown in FIG. 5 (a) of Test Example 4, the LAS concentration measurement value of zero floated to about 0.2 mg /
It is L. This is an excitation wavelength of 210 nm, 230
At each nm, river water (Tokyo: Asakawa, 12
As can be seen from the difference in the fluorescence intensity at the wavelength of 290 nm (for monthly sampling) (see the fluorescence spectrum in FIG. 8), it was suggested that LAS was already present at about 0.2 mg / l at the time of sampling water. To do.

As described above, the sample water is excited with two wavelengths of ultraviolet light, the difference in fluorescence intensity of the emitted specific wavelength (detection wavelength) is measured, and the concentration of the target component is determined to obtain the concentration of the river water or lake. Anionic surfactants in sample water, such as water, in which the blank is not constant can be measured without contact and without reagents.

That is, of the two excitation wavelengths, one wavelength is used for detecting the target component and the remaining one wavelength is used for detecting the blank. Then, it becomes possible to measure and correct the blank for each sample water by obtaining the difference in the fluorescence intensity of the specific wavelength when the sample water is excited by the ultraviolet rays of two wavelengths, and the samples having greatly different water qualities can be obtained. It is possible to measure with water.

Further, as is clear from the above description, according to the method of this embodiment, the fluorescence emission of the sample water is detected by the irradiation of the excitation wavelength of 2 wavelengths in a non-contact manner and without any reagent. Since blank measurement and correction can be performed for each water, continuous measurement can be supported.

Regarding the target water quality index, the excitation wavelength and the detection wavelength of two wavelengths may be generally selected as follows. That is, there is no difference in the fluorescence intensity detected by the two types of excitation wavelengths when measuring the sample water that does not contain the target substance, and when measuring the sample water that contains the target substance, the two types of excitation Based on the fact that the fluorescence intensity detected by the wavelength causes a difference according to the concentration of the target substance, 2
The excitation wavelength and the detection wavelength of the wavelength may be selected.

L which is a sulfonic acid type anionic surfactant
In the case of AS quantification, the detection wavelength is 270 nm to 3 in the wavelength range.
The fluorescence wavelength has a center wavelength in the range of 00 nm, and preferably has a center wavelength of 290 nm. In addition, one of the two excitation wavelengths has a wavelength range 21 for detecting LAS.
Ultraviolet light having a central wavelength in the range of 0 nm to 240 nm,
Ultraviolet rays having a central wavelength of 230 nm are preferably used. The other one excitation wavelength is used for detecting the blank in the wavelength range 20.
Ultraviolet light having a central wavelength in the range of 0 nm to 220 nm,
Ultraviolet rays having a central wavelength of 210 nm are preferably used.

In this example, when the water quality index (water pollutant) to be measured is an anionic surfactant, in particular, a linear alkylbenzene sulfonate (LAS) which is a sulfonic acid type anionic surfactant. However, by applying the above-described principle of selecting the excitation wavelength and the detection wavelength, it is possible to measure another water quality index (measurement target), for example, oil content.

Example 2 (Measurement of BOD) Next, the case where the water quality measuring method of the present invention is applied to the measurement of BOD as a water quality index will be described.

As described above, it was reported that a substantially linear correlation between BOD and fluorescence intensity was obtained by measuring the fluorescence intensity of a predetermined wavelength with one excitation wavelength for the treated water in the sewage treatment facility. Has been done.

The present inventor changed the excitation wavelength variously,
Obtain fluorescence spectra of river water sampled from various locations
The relationship between D and the fluorescence intensity of sample water was examined.

(Test Example 5) River water [Tokyo: Asakawa 1 (8
Monthly sampling), Tokyo: Asakawa 2 (December sampling), Nagano: Mudagawa, Gunma: Takigawa, Gunma: Kondogawa, Osaka: Yodogawa]
For, a fluorescence spectrum was obtained in the same manner as in Example 1. That is, each of the test water (river water) was detected by a peristaltic pump with a fluorescence detector (manufactured by JASCO Corporation: model number F).
P-920) at a flow rate of 1 ml / ml and the excitation wavelength was changed (200 nm to 460 nm) to obtain fluorescence spectra.

As a result, the wavelength of 4
A fluorescence peak appears near 40 nm, and the excitation wavelength is 320
In nm, it was found that the BOD value separately measured by the standard dilution method (hand analysis) and the fluorescence intensity show a substantially linear correlation. The BOD value is measured by manual analysis using a DO electrode according to Japanese Industrial Standards (JIS K 01022).
1. ). The fluorescence intensity was measured at the start of the BOD measurement by such manual analysis.

FIG. 6 shows the fluorescence spectrum of each sample water at an excitation wavelength of 320 nm. In addition, FIG. 7 shows the fluorescence intensity at a wavelength of 440 nm read from this fluorescence spectrum.
As shown in, the relationship between the fluorescence intensity and the BOD value by manual analysis was obtained.

From this result, in principle, by measuring the fluorescence intensity at 440 nm as the detection wavelength using 320 nm as the excitation wavelength for river water, the BOD can be measured.
It is considered possible to measure

However, further studies by the present inventor have revealed the following. That is, when the water quality varies depending on the water system, the fluorescence emitted by being excited by the ultraviolet rays greatly differs depending on each sample water (water sampling place). Therefore, for example, for highly closed lake water, from the correlation between the fluorescence intensity at a wavelength of 440 nm by the same single excitation wavelength of 320 nm obtained for river water and the BOD value by manual analysis as described above, It has been found that it is not possible to measure BOD.

Therefore, as a result of intensive studies by the present inventor, B
Also in the measurement of OD, the same method as in Example 1 is applied and a specific detection wavelength (fluorescence wavelength) by two excitation wavelengths is applied.
It was found that by measuring the fluorescence intensity of the sample water in, the good correlation between the fluorescence intensity and the BOD by the manual analysis can be obtained for the sample water with different water quality, for example, river water and lake water. . This point will be further described by the following test example.

(Test Example 6) River water, lake water as sample water [Tokyo: Asakawa 2 (December sampling), Tokyo: Asakawa 3 (6)
Monthly sampling), Tokyo: Asakawa 4 (June sampling), Nagano: Mudagawa, Gunma: Takigawa, Nagano: Lake Kamahara, Ibaraki: Kasumigaura]
The same two excitation wavelengths as in Example 1, 210 nm,
Fluorescence spectra were obtained using 230 nm. Also, for each sample water, BOD was obtained by manual analysis in the same manner as in Test Example 5.
Was measured. A part of the obtained fluorescence spectrum is shown in FIG.

Here, it is considered that the measurement of BOD using the ultraviolet fluorescence method is generally equivalent to the measurement of the blank itself in the LAS measurement of Example 1. Therefore,
In the measurement of BOD, it was examined to use a wavelength that avoids the peak wavelength at which the fluorescence intensity largely changes depending on the water system, as the detection wavelength. In this example, the wavelength of 420 nm at which the excitation wavelength of 230 nm used for detecting LAS in Example 1 does not have a fluorescence peak of sample water and a certain level of fluorescence intensity is obtained is set as the detection wavelength.

As a result, two excitation wavelengths of 210 nm and 2
By obtaining the difference in fluorescence intensity at 30 nm, it was found that an extremely good linear correlation with the BOD measurement value by manual analysis was obtained for both river water and lake water. The results are shown in Table 5 and FIG.

However, in the measurement of BOD of this example, the value obtained by subtracting the fluorescence intensity when pure water was irradiated with ultraviolet light of 210 nm from the fluorescence intensity of 420 nm of the sample water at the excitation wavelength of 210 nm was the blank detection value. And In the measurement of LAS of Example 1, since the standard solution was obtained by adding LAS to pure water, simply measuring the fluorescence intensity of the detection wavelength of 290 nm by the excitation wavelength of 230 nm, the excitation wavelength of 210 n
The blank was corrected by subtracting the fluorescence intensity at the detection wavelength of 290 nm by m. In the case of the BOD measurement of this example, a better correlation with the BOD value by manual analysis could be obtained by correcting the fluorescence of pure water in the sample water as described above.

[0080]

[Table 5]

As can be seen from FIG. 9, by obtaining the difference in fluorescence intensity between the two excitation wavelengths and performing blank correction, both river water and lake water have a very good linear correlation with the BOD measurement value by manual analysis. It turned out to be obtained.
On the other hand, as shown in FIG.
It can be seen that the linearity of the correlation between the fluorescence intensity at a wavelength of 420 nm at 0 nm and the BOD measurement value by manual analysis is poor.

Therefore, for various sample waters (river water, lake water, etc.), the correlation between the BOD measurement value by manual analysis and the difference in the fluorescence intensity of the specific wavelengths due to the two excitation wavelengths can be obtained in advance to obtain an arbitrary value. The BOD of the sample water can be measured. At this time, it is preferable to obtain the difference between the fluorescence intensities of the specific wavelengths by the two excitation wavelengths using a value obtained by blank-correcting the fluorescence intensity of the specific wavelengths by the excitation wavelength for blank detection with respect to the fluorescence of pure water.

As described above, the BOD of the sample water can be measured by exciting the sample water with two excitation wavelengths and measuring the difference in fluorescence intensity of the emitted specific wavelength (detection wavelength). That is, one of the two excitation wavelengths is BO
D detection and the remaining 1 wavelength are used for blank detection.
Then, it becomes possible to measure and correct the blank for each sample water by obtaining the difference in the fluorescence intensity of the specific wavelength when the sample water is excited by the ultraviolet rays of two wavelengths,
It is possible to measure even with sample water whose water quality is greatly different.

Further, as is clear from the above description, according to the method of this embodiment, the sample water is detected by detecting the fluorescence emission of the sample water by irradiation with the excitation wavelength of 2 wavelengths without contact and without any reagent. Since the blank can be measured and corrected for each water, it is possible to correspond to the continuous BOD measurement.

Furthermore, by obtaining the correlation between BOD and fluorescence intensity, BOD can be predicted and can be used as an index of the dilution rate when BOD is measured by the standard dilution method.

Regarding the BOD measurement, generally, the excitation wavelength and the detection wavelength of the two wavelengths may be selected as follows. That is, if the excitation wavelength and the detection wavelength of two wavelengths are selected on the basis that the peak does not appear even when the sample water is excited, and that the difference in the fluorescence intensity according to the BOD can be obtained even if there is no peak. Good.

In the case of BOD measurement, the detection wavelength is a fluorescence wavelength having no central wavelength in the wavelength range of 390 nm to 440 nm, preferably a fluorescent wavelength of 420 nm. For one of the two excitation wavelengths, ultraviolet light having a center wavelength in the wavelength range of 210 nm to 240 nm, preferably ultraviolet light having a center wavelength of 230 nm, is used for detecting BOD. For the other one excitation wavelength, ultraviolet light having a central wavelength in the wavelength range of 200 nm to 220 nm, preferably ultraviolet light having a central wavelength of 210 nm is used for detecting a blank.

Embodiment 3 Next, an embodiment of the water quality measuring device of the present invention will be described with reference to FIGS. In this example,
The measurement of an anionic surfactant as a water quality index will be described as an example.

The water quality measuring apparatus 1 of this example was prepared according to the method described in Example 1 by using an anionic surfactant,
In particular, linear alkylbenzene sulfonates (LAS) that are sulfonic acid type anionic surfactants can be continuously measured (monitored).

As schematically shown in FIG. 10, the water quality measuring device 1 is provided with a detection unit 2, a control unit 3, a sample tank 4 as a sample water container, and an operation unit 5, and the sample tank 4 has a predetermined flow rate. The continuous measurement of LAS in the sample water continuously introduced is carried out.

The sample tank 4 is provided with a sample water inlet 41 and a sample outlet 42. The sample water flows into the sample tank 4 from a desired sample water supply source, for example, a river, by a pump 61 through a pipe line 62 connected to the inflow port 41. Sample water is
It is discharged from the sample tank 4 to a predetermined discharge destination, for example, a sample water supply source, via a pipe 63 connected to the outlet 42.
Further, valves 64 and 65 for restricting the introduction of the sample water from the sample water supply source to the pipe 62 and the drainage of the sample water from the pipe 63 are provided. Further, the sample tank 4 is provided with a measurement opening 43 connected to the optical path 16 of the detection unit 2 described later.

The detecting section 2 irradiates the sample water introduced into the sample tank 4 with the ultraviolet excitation wavelength, and outputs an electric signal corresponding to the intensity of the fluorescence emitted from the sample water to the control section 3.

FIG. 11 shows the detector 2 of the water quality measuring device 1 in more detail. The light projecting unit 10 of the detecting unit 2 includes a light source 10a,
A lens system 12 and an excitation wavelength selection means 13 are provided. In this embodiment, the light source 10a has a wavelength of 200 nm.
A Xe flash lamp (xenon discharge tube) that emits light of ˜800 nm was used. The light emitted from the light source 10a is directed to the dichroic mirror 14 via the lens system 12 and the excitation wavelength selecting means 13. Lens system 12
Converts the excitation light from the light source 10a into parallel light.

In this embodiment, the excitation wavelength selection means 13 is
As the spectroscopic means, there are provided a first optical filter 13a such as an interference film band-pass filter that transmits an excitation wavelength having a center wavelength of 210 nm, and a second optical filter 13b that transmits an excitation wavelength having a center wavelength of 230 nm. or,
The excitation wavelength selection means 13 includes the first and second optical filters 1
3a and 13b are supported by a filter support 13c which is a rotating body. In this way, the filter support 13c rotates based on a signal from the arithmetic means 31 of the control unit 3 described later, and sequentially arranges desired optical filters at positions where the light flux from the light source 10a passes. This makes the wavelength 2
The sample water is irradiated with ultraviolet rays of 10 nm and 230 nm at desired timings.

The dichroic mirror 14 used in this embodiment transmits light having a wavelength of 260 nm or more and reflects light having a shorter wavelength. Therefore, wavelengths 210 nm, 23
The 0 nm ultraviolet ray is reflected by the dichroic mirror 14.

The ultraviolet ray having the excitation wavelength reflected by the dichroic mirror 14 has its optical axis bent substantially at a right angle and is directed substantially vertically downward in this embodiment. Then, the ultraviolet ray having the excitation wavelength passes through the optical path 16 connected to the measurement opening 43 of the sample tank 4 and is irradiated on the sample water in the sample tank 4. A lens system 15 is arranged in the optical path 16,
The excitation light is focused on the liquid surface of the sample water.

On the other hand, the fluorescence emitted from the sample water is the lens system 1
It is collimated through 5 and travels to the dichroic mirror 14. Then, the fluorescence transmitted through the dichroic mirror 14 is directed to the fluorescence detection unit 21.

In this embodiment, the fluorescence detecting section 21 is provided with a photodetector 21a, a third optical filter 19 such as an interference film bandpass filter which is a spectroscopic means, a lens system 20 and the like. In this embodiment, the third optical filter 1
Reference numeral 9 transmits light having a central wavelength of 290 nm. Then, the fluorescence that has passed through the optical filter 19 is focused on the photodetector 21a by the lens system 20. In this embodiment, a photomultiplier tube is used as the photodetector 21a.

The photodetector 21a emits an electric signal corresponding to the detected fluorescence intensity. This signal is input to the control unit 3 via a detection circuit (not shown) including a current-voltage converter (amplifier) and an A / D converter (FIG. 11).

The light emitted from the light projecting unit 10 and transmitted through the dichroic mirror 14 is focused on the reference light detector 18a by the lens system 17 in the reference light receiving unit 18. The reference photodetector 18a emits a signal corresponding to the amount of received light, and this signal is input to the calculation means 31 of the control unit 3 and used for controlling the light amount of the light source 10a and the like.

Further, all the optical components of the detecting section 2 are housed in the light shielding case 22. Further, the light path 16 connected to the light shielding case 22 and the sample tank 4 are also shielded from light.

The control section 3 includes a calculation means 31 and a storage means 32.
And the like, which collectively controls the operation of the apparatus in accordance with the program stored in the recording means 32, performs arithmetic processing based on the output of the detection unit 2 and the information stored in the storage means 32, and LAS in the sample water. A signal corresponding to the density is generated.

That is, the calculation means 31 turns on the light source 10a at a predetermined timing, and the excitation wavelength selection means 1
First optical filter 13a, second optical filter 1
3b is moved to the light transmission position, and the excitation wavelength 210n
The sample water introduced into the sample tank 4 is irradiated with ultraviolet rays of m and 230 nm.

290 detected by the fluorescent light receiving element 31a
The signal corresponding to the fluorescence intensity of nm is calculated by the calculation means 3 of the control unit 3.
Input to 1. The calculation means 31 is the excitation wavelength selection means 1
In synchronization with the operation of the rotating body 13c of No. 3, the excitation wavelength of the fluorescence intensity is recognized and stored in the storage unit 32 or the storage unit built in the calculation unit 31.

Information corresponding to the calibration curve III obtained in Test Example 1 of Example 1 previously stored in the storage means 32, that is, the wavelength of the LAS standard solution of 290 nm at the excitation wavelengths of 210 nm and 230 nm, respectively. The information indicating the relationship between the fluorescence intensity and the LAS concentration in is stored.

As a result, the calculation means 31 calculates based on the fluorescence intensity input from the detection section 2 and the information of the calibration curve stored in the storage means 32 in advance, and the LAS in the sample water is calculated.
Information corresponding to the density is generated. Further, the calculation means 31 is
Based on the information, the display unit 51 such as a liquid crystal display of the operation unit 5 displays the LA in a desired display form.
A signal is generated to display information indicating the S concentration measurement value.

The operation section 5 is provided with a display means 51 for displaying the measurement result, an input means 52 for setting the device parameters, starting and stopping the measurement, and inputting desired data. The information on the above-mentioned calibration curve can be stored in the recording means 32 in advance, but can be appropriately input from the operation unit 5 or the operation unit 5
From the above, a calibration step may be designated to create (store) a calibration curve using a predetermined standard solution before starting the measurement.

As the control unit 3, it is possible to use a computer communicatively connected to the detection unit 2 such as a personal computer. Further, it is naturally possible to display the measurement result on a display screen of a computer connected to the apparatus as a display unit or to output it by a printer connected to the computer.

In the above description, the case of LAS measurement is described as an example, but the above configuration is basically the same as that described in the second embodiment.
It is similarly applicable to the measurement of OD. For example, in order to carry out the method described in the second embodiment, the fluorescence detection unit 21
As the third optical filter 19 which is the spectroscopic means, a filter that transmits light having a center wavelength of 420 nm may be used.

As described above, according to the present embodiment, the water quality measuring method of the present invention is preferably carried out, and the water quality index (water pollutant) of sample water, for example, river water, lake water, etc., for example, anionic surface activity. Agents, especially sulfonic acid type anionic surfactants (L
AS, etc.) and BOD can be continuously measured without contact and without reagents.

Although the water quality measuring apparatus according to the present invention has been described above with reference to the specific embodiments, it is understood that the present invention is not limited to the exact configuration and arrangement in the above embodiments. I want to.

For example, in the present embodiment, the light projecting section 10 has been described as selecting light from one light source 10 by the excitation wavelength selecting means 13 having a plurality of spectroscopic means and irradiating the sample water. The invention is not limited to this configuration. Providing a plurality of light projecting units equipped with the above-mentioned light source, lens system, spectroscopic means, etc., and selectively using the desired optical members (mirror system, lens system, splitter, chopper, etc.) to emit ultraviolet rays having a predetermined excitation wavelength. It is possible to introduce fluorescence into the sample water on the same optical path and detect fluorescence of the sample water with the same tendency detecting unit 21. Alternatively, a plurality of units of the configuration of the detection unit 2 of the present embodiment (there is no need to have an excitation wavelength selection unit) as a unit, and fluorescence when the sample water is irradiated with ultraviolet rays having a predetermined excitation wavelength by each unit. However, it does not matter even if it is configured to obtain the measured value by detecting and calculating by the control unit.

In this embodiment, the light source 10a provided in the light projecting section 10 is a Xe flash lamp (xenon discharge tube).
Yes, but not limited to. For example, a D ₂ lamp (deuterium discharge tube) can also be used. Further, the present invention is not limited to disperse the light from the light source 10a by the spectroscopic means and irradiate the sample water with ultraviolet rays having a predetermined excitation wavelength. If a light source that emits ultraviolet rays having a desired center wavelength, such as a laser light source, is available, the spectroscopic means can be omitted by using it. Further, as the photodetector 21a, a photomultiplier tube, a photodiode,
A phototransistor, an avalanche photodiode, or the like can be used as appropriate.

In this specification, ultraviolet rays have a wavelength of 1
It refers to light rays of 90 nm to 400 nm. In the present specification, the term “fluorescence” includes any light emitted by the sample water when it is irradiated with a light beam having a predetermined excitation wavelength.

[0115]

As described above, according to the present invention,
Water quality indicators related to sample water such as river water and lake water, for example, anionic surfactants in sample water, especially sulfonic acid type anionic surfactants (LAS etc.) and BOD are measured without contact and without reagents. It is possible to cope with continuous measurement. Further, according to the present invention, the BOD of sample water such as river water and lake water can be predicted, and it can be used as an index of the dilution rate of sample water when measuring BOD by the standard dilution method. . Furthermore, according to the present invention, a calibration curve can be easily created with a simple structure, and the anionic surfactant in the sample water is always stable, particularly, a sulfonic acid type anionic surfactant (such as LAS), BOD can be measured without contact and without reagents, and continuous measurement is possible.

[Brief description of drawings]

FIG. 1 Linear alkylbenzene sulfonates (LA
It is a graph which shows the fluorescence spectrum of S) aqueous solution.

FIG. 2 Linear alkylbenzene sulfonates (LA
It is a graph which shows the correlation of the density | concentration of S), and fluorescence intensity.

FIG. 3 is a graph showing the relationship between the amount of LAS added from a neutral detergent and the LAS concentration measured by a water quality measurement method when a commercially available neutral detergent is added to pure water.

FIG. 4 Linear alkylbenzene sulfonates (LA
It is a graph which shows the relationship between the LAS addition amount at the time of adding S) to river water, and the LAS concentration measured value by a water quality measuring method.

FIG. 5 shows the relationship between the amount of LAS added from a neutral detergent and the LAS concentration measured by a water quality measurement method when a commercially available neutral detergent was added to (a) river water and (b) lake water, respectively. It is a graph figure.

FIG. 6 is a graph showing a fluorescence spectrum of river water sampled from various places.

FIG. 7 is a graph showing the correlation between the fluorescence intensity of river water sampled from various places and the BOD measurement value by manual analysis.

FIG. 8 is a graph showing fluorescence spectra of river water and pure water.

FIG. 9 is a graph showing a relationship between fluorescence intensity of river water and lake water sampled from various places and BOD measurement value by manual analysis.

FIG. 10 is a block diagram for explaining a schematic configuration of an embodiment of a water quality measuring device according to the present invention.

11 is a schematic cross-sectional view for explaining one embodiment of the detection unit of the water quality measuring device of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Water quality measuring device 2 Detection part 3 Control part 4 Sample tank (sample water storage part) 10 Projection part 10a Light sources 13a and 13b 1st, 2nd optical filter (spectral means) 19 3rd optical filter (spectral means) 21 fluorescence detector 21a photodetector 31 computing means 32 storage means

Claims (16)

[Claims] 1. A sample water is irradiated with at least two different wavelengths of ultraviolet rays, and the fluorescence intensity of a specific wavelength emitted by the sample water by each wavelength of ultraviolet rays is measured. A method for measuring water quality, characterized in that a specific water quality index amount of sample water is measured based on this. 2. The water quality measuring method according to claim 1, wherein the specific water quality index amount is the amount of linear alkylbenzene sulfonates in the sample water. 3. The water quality measuring method according to claim 1, wherein the specific water quality index amount is a biochemical oxygen demand amount of sample water. 4. The sample water is irradiated with ultraviolet rays of two different wavelengths, the fluorescence intensity of the specific wavelength emitted by the sample water is measured by the ultraviolet rays of each wavelength, and the difference in the fluorescence intensity of the specific wavelength with respect to the ultraviolet rays of each wavelength is calculated. A method for measuring water quality, characterized in that the amount of straight-chain alkylbenzene sulfonates in sample water is measured by determining. 5. The water quality measuring method according to claim 4, wherein the ultraviolet rays having two different wavelengths have central wavelengths of 210 nm and 230 nm, respectively, and the specific wavelength has a central wavelength of 290 nm. 6. The sample water is irradiated with ultraviolet rays of two different wavelengths, the fluorescence intensity of the specific wavelength emitted by the sample water is measured by the ultraviolet rays of each wavelength, and the difference in the fluorescence intensity of the specific wavelength with respect to the ultraviolet rays of each wavelength is measured. A method for measuring water quality, characterized by measuring the biochemical oxygen demand of the sample water by determining. 7. The difference between the fluorescence intensities of the specific wavelengths with respect to the ultraviolet rays of the respective wavelengths is determined from the fluorescence intensity of the specific wavelengths with respect to the ultraviolet rays of at least one wavelength, which is generated when the pure water is irradiated with the ultraviolet rays of the wavelength The water quality measuring method according to claim 6, wherein the water quality is determined by using the fluorescence intensity obtained by subtracting the fluorescence intensity of the wavelength. 8. The water quality measuring method according to claim 6, wherein the ultraviolet rays having two different wavelengths have central wavelengths of 210 nm and 230 nm, respectively, and the specific wavelength has a central wavelength of 420 nm. 9. A sample water container to which the sample water is supplied, a projecting unit for irradiating the sample water in the sample water container with ultraviolet rays of at least two different wavelengths, and the sample water is emitted by the ultraviolet rays of each wavelength. A fluorescence detection unit that detects fluorescence of a specific wavelength, and a calculation that calculates a specific water quality index amount of sample water based on a signal emitted by the fluorescence detection unit according to the fluorescence intensity of the specific wavelength with respect to the detected ultraviolet light of each wavelength. And a water quality measuring device. 10. The calculation means measures a specific water quality index amount of sample water by obtaining a difference in fluorescence intensity of the specific wavelength with respect to ultraviolet rays of each wavelength based on a signal from the fluorescence detection unit. The water quality measuring device according to claim 9. 11. A storage means for storing in advance information indicating a correlation between a difference in fluorescence intensity of the specific wavelength with respect to ultraviolet rays of each wavelength and a specific water quality index amount of the sample water, and the arithmetic means. A difference in fluorescence intensity of the specific wavelength with respect to ultraviolet rays of each wavelength obtained based on the signal from the fluorescence detection unit, information stored in advance in the storage unit, based on a specific water quality index amount of the sample water It measures, The water quality measuring device of Claim 10 characterized by the above-mentioned. 12. The sample water is continuously supplied to the sample water container, and the specific water quality index amount of the sample water is continuously measured. Water quality measuring device. 13. The water quality measuring device according to claim 9, wherein the specific water quality index amount is linear alkylbenzene sulfonates in the sample water. 14. The center wavelength of each of the light projecting portions is 2
The water quality measuring device according to claim 13, wherein the sample water is irradiated with ultraviolet rays of 10 nm and 230 nm, and the fluorescence detecting section detects fluorescence having a center wavelength of 290 nm. 15. The specific water quality index amount is a biochemical oxygen demand amount of sample water.
12 water quality measuring devices. 16. The center wavelength of each of the light projecting portions is 2
The water quality measuring device according to claim 15, wherein the sample water is irradiated with ultraviolet rays of 10 nm and 230 nm, and the fluorescence detecting section detects fluorescence having a center wavelength of 420 nm.