JP7119491B2 - Water quality analysis method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water quality analysis method, and more particularly to a water quality analysis method using a water quality analyzer based on a measurement principle of colorimetry or nephelometry.

In an on-line water quality analyzer, sample water is injected into the measurement cell, a measurement reagent is added according to the measurement item to cause color development or cloudiness, and the change in absorbance before and after addition of the measurement reagent is measured to determine the amount of chemicals in the sample water. Concentration is calculated (Patent Documents 1 and 2).

In the conventional water quality analysis method, when a reagent is added and mixed in the measurement cell, the reagent is flown through the constant flow valve 12 provided upstream of the measurement cell 1 as shown in FIG. 2 (Comparative Example 2) described later. Sample water was sampled by pulsation generated by opening and closing the electromagnetic valve 11 . However, in this method, since the flow paths of the constant flow valve 12 and the solenoid valve 11 are narrow, the constant flow valve 12 and the solenoid valve 11 are clogged due to SS (suspended solids) in the sample water and fouling derived from microorganisms. There was a problem that the stirring of the reagent became insufficient, making normal measurement impossible.

That is, when the constant flow valve 12 or the solenoid valve 11 is blocked and the amount of permeated water is reduced, the measurement reagent is not stirred sufficiently, and the measurement result is unstable. The constant flow rate valve 12 is installed to allow a constant amount of sample water to flow into the measuring cell 1 even if the pressure of the sample water fluctuates when the solenoid valve 11 is open. If too much sample water flows into the measuring cell 1, the added reagent will flow out of the measuring cell 1, making measurement impossible.

Japanese Unexamined Patent Application Publication No. 2010-181150 JP 2014-186027 A

As described above, in the conventional technology, the sample water and the measurement reagent are stirred in the measurement cell by opening and closing the electromagnetic valve provided upstream of the measurement cell, and by the pulsation generated. In addition, since the flow path of the solenoid valve is narrow, it may be clogged by fouling derived from SS or microorganisms in the sample water, and the agitation of the measurement reagent may become insufficient, making normal measurement impossible.

SUMMARY OF THE INVENTION An object of the present invention is to provide a water quality analysis method in which sample water and a measurement reagent are sufficiently agitated in a measurement cell, measurement accuracy is improved, and clogging of the flow path is prevented.

In the water quality analysis method of the present invention, a measurement reagent is supplied into a measurement cell, a sample water is supplied into the measurement cell, the measurement reagent and the sample water are stirred, and then the sample water in the measurement cell absorbs light or In a water quality analysis method using a water quality analyzer that measures scattering using a light-emitting body and a light-receiving body, after supplying a measurement reagent into the measurement cell, the tube pump for supplying sample water is operated for a short time to supply sample water into the measurement cell. It is characterized by stirring the measuring reagent and the sample water by supplying.

In the present invention, preferably, the tube pump is operated for 0.1 to 0.2 sec when supplying the sample water, and 20 to 40% of the volume of the measuring cell is supplied to the measuring cell.

In the present invention, sample water is supplied to the measuring cell by a tube pump. The tube pump pulsates the discharged water. In the present invention, this pulsation agitates the sample water and the measurement reagent in the measurement cell. According to this method, the sample water and the measurement reagent are sufficiently stirred, and highly accurate water quality analysis can be performed. In addition, by not using a solenoid valve and a constant flow valve, clogging of the flow path is also prevented.

1 is a schematic cross-sectional view of a water quality analyzer according to an embodiment; FIG. FIG. 2 is a schematic cross-sectional view of a water quality analyzer according to a conventional example; It is a graph which shows an experimental result. It is a graph which shows an experimental result.

An embodiment will be described with reference to FIG. The measuring cell 1 has an inlet 2 and an outlet 3 for sample water. One side surface of the measurement cell 1 is a transparent portion 4 , and the cell inner surface on the opposite side of the transparent portion 4 is a white reflective surface 5 . A cover 8 is provided so as to cover the outside of the transparent portion 4. Inside the cover 8, a light emitter 6 such as a light emitting diode and a light receiver 7 such as a photodiode are provided. Light from the light emitter 6 passes through the sample water in the cell 1, is reflected by the reflecting surface 5, passes through the sample water, is received by the photoreceptor 7, and absorbance is measured. The volume of the cell 1 is preferably about 0.3 to 3.0 mL, particularly about 0.5 to 1.0 mL, but is not limited to this.

Sample water is supplied to the measuring cell 1 by a tube pump 10 . In the present invention, preferably after supplying the measuring reagent into the measuring cell 1 , sample water of 20 to 40% of the volume of the measuring cell 1 is supplied to the measuring cell 1 . The tube pump 10 pulsates the discharged water, and the pulsation sufficiently agitates the sample water and the measurement reagent in the measurement cell 1 .

Further, the tube pump 10 is less prone to clogging due to SS or biofouling. Therefore, according to the present invention, highly accurate water quality measurement can be performed over a long period of time.

In Comparative Example 1 and Example 1 below, benzethonium chloride and a pH buffer aqueous solution were used as measurement reagents, and open circulation cooling water in actual operation was used as sample water.

[Comparative Example 1]
As shown in FIG. 2, after adding 0.06 mL of the measurement reagent to the measurement cell (volume 0.7 mL), the solenoid valve is opened for 0.2 to 0.4 sec, and 15 to 30% of the volume of the measurement cell is sampled. Water was supplied in pulses into the measurement cell and stirred with the measurement reagent (at this time, the sample water supply rate was measured by a flow meter). The sensor values were then read and the polymer concentration determined based on the calibration curve. 2 and 3 show changes over time in sample water supply rate and polymer concentration.

[Example 1]
After adding the measurement reagent to the inside of the measurement cell, as shown in FIG. supplied to Other than that, the test was conducted under the same conditions as in Comparative Example 1. 2 and 3 show changes over time in sample water supply rate and polymer concentration.

[Reference example 1]
Sample water was taken and the polymer concentration in the sample water was analyzed by nephelometric method. The results are shown in FIG. 3 as laboratory analysis values.

As shown in FIG. 3, the values of Example 1 substantially match those of Reference Example 1. On the other hand, in Comparative Example 1, the divergence from the value in Reference Example 1 is large. From this experimental result, it was confirmed that the present invention enables highly accurate measurement.

Also, as shown in FIG. 2, according to the present invention, it was found that the water flow rate to the measuring cell was kept constant over a long period of time.

REFERENCE SIGNS LIST 1 measurement cell 5 reflective surface 6 light emitter 7 light receiver 10 tube pump 11 solenoid valve 12 constant flow valve

Claims (1)

After supplying the measuring reagent into the measuring cell, supplying the sample water into the measuring cell, and stirring the measuring reagent and the sample water, the light absorption or scattering by the sample water in the measuring cell is detected by the light-emitting body and the light-receiving body. In the water quality analysis method using the water quality analyzer to be measured, after supplying the measurement reagent into the measurement cell, the sample water supply tube pump is operated for 0.1 to 0.2 sec to fill the measurement cell with 20% of the volume of the measurement cell. A water quality analysis method characterized by supplying ~40% sample water and stirring the measurement reagent and the sample water.

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