JP4367240B2 - Automatic water quality measuring instrument - Google Patents

Description

  The present invention relates to a water quality analyzer for measuring, inspecting or managing components contained in sample water such as waste water, sewage, environmental water, plant water, etc. For example, total nitrogen (TN), total phosphorus contained in sample water (TP) relates to a water quality analyzer capable of measuring at least one of organic pollutants.

In Japan, methods for measuring organic pollutants, nitrogen compounds, and phosphorus compounds in water are officially standardized by JIS K0102 Environmental Agency Notification No. 140.
The analysis method of the water quality analyzer first converts nitrogen compounds in sample water into nitrate ions and phosphorus compounds into phosphate ions.
The nitrogen compound is measured by adjusting the pH to 2-3 and measuring the ultraviolet absorbance at a wavelength of 220 nm.

  On the other hand, since the phosphoric acid ion does not have a specific light absorption, the phosphorous compound is measured by adding an ammonium molybdate solution and an L-ascorbic acid solution as color formers, and measuring the absorbance at a wavelength of 880 nm. Yes.

  In addition, in Japan, the total amount of organic pollutants has already been regulated for industrial wastewater flowing into closed sea areas to protect the water environment, and UV (ultraviolet) meters, TOC (total organic carbon) meters, BOD (biochemical oxygen demand) meter, COD (chemical oxygen demand) meter, etc. are adopted as official methods. Among them, the UV meter is most popular due to its simple structure.

When water quality analysis is performed, drainage, sewage, and environmental water are pumped up and supplied to the analysis unit by a sample sampling unit provided in the apparatus (see Patent Document 1). However, when the sample water collection unit of the water quality analyzer collects, for example, drainage or sewage, organic pollutants contained in the sample water adhere to the inside and accumulate, or a microbial membrane (for example, , Slime, etc.) may adhere and grow due to nutrients and sunlight contained in the sample water. In addition, when sampling a sample with an automatic water quality measuring instrument, the sampling tube after sample sampling is usually filled with the sample or water until the next sample sampling. Contamination of the sample sampling part with water is removed by periodic manual cleaning.
JP 2001-296290 A

When the sample water collection part of the automatic water quality measuring instrument is always filled with the sample or water, the components in the sample adhere to the inner wall of the supply tube after sample water sampling, and this will affect the contamination during the next measurement. As a result, there were problems such as inability to measure accurately.
In the case where the sample supply tube is manually washed for each measurement as conventionally performed, labor and time are required. In the case of a continuous analyzer, since the measuring device must be stopped during cleaning, a period during which measurement data cannot be obtained, that is, a missing period occurs, which hinders continuous analysis.
Accordingly, an object of the present invention is to automatically clean the supply tube inside the sample water collection unit.

The present invention includes an analysis unit that measures a specific component concentration in sample water, a sample collection unit that supplies sample water to the analysis unit via a sample supply tube, and a control unit that controls the operation of the sample collection unit. In the automatic water quality measuring instrument provided, the control unit controls the washing reagent to flow through the tube before and / or after sample collection.
An example of the reagent for washing the tube is an acid and / or alkaline solution.
As the cleaning reagent, a reagent used for measurement may be used.
Before and / or after sample collection means the meaning of one or both before and after sample collection, and the acid and / or alkaline solution also means the meaning of one or both.

By controlling and automating the cleaning of the sample supply tube with the reagent before and / or after sample water sampling, it is possible to prevent the influence of contamination as a contamination at the next measurement.
In addition, the configuration of the apparatus can be simplified by using the same reagent as that used for sample analysis as the reagent to be washed.

FIG. 1 is a cross-sectional view schematically showing a sample water collecting portion of a water quality analyzer of one embodiment.
In this embodiment, a sample water sampling unit in an on-line TOC meter will be described.
This sample water sampling unit 1 is provided with a partition plate 4 having a height about half that of the water sampling container 2 at the center, and by this partition plate 4, a sample sampling unit 2 a for collecting sample water and a sample collected are collected. It is divided into a homogenizer 2b which is stirred and homogenized and supplied to the TOC measuring unit 19.
A member 10 indicated by a broken line is a strainer, and removes dust in the sample water flowing from the sample collection unit 2a to the homogenizer 2b over the partition plate 4 during sample collection.

  Reference numeral 6 denotes a supply tube that supplies sample water to the water collection container 2, and is attached to the side surface of the sample collection part 2 a of the water collection container 2. Denoted at 8 and 16 are drain pipes for discharging the sample water of the sample collection section 2a and the homogenizer 2b to the outside, and these are opened and closed by electromagnetic valves 9 and 17, respectively.

A sample supply tube 12 for supplying sample water to the TOC measuring unit 19 is attached below the side surface of the homogenizer 2b. The TOC measurement unit 19 can guide the sample water supplied from the sample supply tube 12 to the measurement unit, and can flow cleaning water or a reagent in the reverse direction to the sample supply tube 12. 14 is a stirrer that stirs and homogenizes the sample water in the homogenizer 2b. The stirrer 14 is rotated by a motor (not shown).

From the upper side surface of the homogenizer 2b, a nozzle 20 for ejecting pure water from its tip is inserted as a washing water ejection means. The tip of the nozzle 20 is directed to the strainer 10, and the dirt adhering to the strainer 10 and its periphery is removed by pure water ejected from the tip.
In the side surface of the sample collection part 2a of the water sampling container 2, a drain outlet 7 is provided at a position higher than the upper end of the partition plate 4, and when the sample water is collected or the amount of sample water supplied to the water sampling container 2 is too large For example, the sample water is discharged from the drain port 7 so that the sample water does not overflow into the water sampling container 2.

The operation will be described below.
The sample water is continuously supplied from the supply tube 6 to the sample collection unit 2a, and the electromagnetic valve 9 is closed and stored in the sample collection unit 2a according to the measurement schedule. When the water level of the sample water accumulated in the sample collection unit 2a exceeds the height of the partition plate 4, the sample water flows through the strainer 10 into the homogenizer 2b. At this time, the dust contained in the sample water flowing into the homogenizer 2 b is removed by the strainer 10. The electromagnetic valve 9 is opened after a predetermined time according to the measurement schedule, and the sample water from the supply tube 6 is discharged from the drain pipe 8.

In the homogenizer 2b, the electromagnetic valve 17 is closed, and the sample water that has flowed in is homogenized by the stirrer 14, and then supplied to the TOC measuring unit 19 through the lower sample supply tube 12. At this time, even if the supply amount of the sample water from the supply tube 6 is larger than the supply amount of the sample water to the TOC measuring unit 19, the water is drained from the drain port 7 when the water level reaches the drain port 7. Does not reach the upper surface of the water sampling container 2.

When the sample water supply to the TOC measuring unit 19 is completed, the electromagnetic valve 17 is opened and the sample water remaining in the homogenizer 2b is discharged from the drain pipes 8 and 16. Thereafter, the reagent is flowed from the TOC measuring unit 19 through the sample supply tube 12 toward the sample water collecting unit 1 and discharged from the drain pipe 16. As the reagent, for example, the inside of the sample supply tube 12 is washed by flowing a hydrochloric acid solution. Subsequently, water flows from the TOC measurement unit 19 to the sample supply tube 12. Thereafter, pure water is ejected as cleaning water from the tip of the nozzle 20 and sprayed onto the strainer 10 and its surroundings for cleaning.
The cleaning of the sample supply tube 12 with the hydrochloric acid solution and water and the cleaning performed by ejecting the cleaning water from the tip of the nozzle 20 can be performed in different orders or simultaneously.

The measurement operation is completed by automatically performing the above washing operation.
The sample supply tube 12 can be cleaned not only after the sample measurement but also before the sample measurement, and the reagent used for the cleaning can be performed with an acid and / or alkali solution. It is also possible to wash the sample supply tube 12 a plurality of times with a plurality of types of reagents, and it is preferable to flow distilled water after washing.

FIG. 2 is a diagram schematically showing the configuration of the total phosphorus measuring apparatus according to one embodiment.
Reference numeral 21 denotes a sample adjusting tank, in which sample water is constantly flowing, and is connected to one port of the port valve 28b via the tube 50, and sample water is collected during measurement.
The sample supply / collection unit 35 of the oxidation reaction unit 32 and the measurement unit 36 are connected to the other port of the port valve 28b, and the common port of the port valve 28b is connected to one port of the other port valve 28a. .

  Containers for storing liquids 22 to 27 such as reagents and measurement calibration water are connected to the respective ports of the port valve 28a by pipes. In this embodiment, the liquid 22 is a color developing agent for molybdenum blue method, ammonium sulfate molybdate / antimonyl potassium tartrate solution, liquid 23 is also a reducing agent L-ascorbic acid solution for color development, and liquid 24 is Sulfuric acid solution for pretreatment of oxidative decomposition, liquid 25 is a sodium hydroxide solution for acid concentration adjustment for color development of molybdenum, liquid 26 is a hydrochloric acid solution, liquid 27 is a phosphorus concentration of zero as blank water for absorbance measurement Assume pure water.

  A syringe pump 37 is connected to a common port of the port valve 28a. The syringe pump 37 is driven by a motor 45, and sample water, a reagent, and the like are passed through the port valves 28a and 28b to the oxidation reaction unit 32 and the measurement unit 36. The reagent can be added to the sample water in the syringe pump 37.

  The oxidation reaction section 32 heats the sample water in the reaction vessel 30 and oxidizes and decomposes the phosphorus compound by irradiating with ultraviolet rays while supplying an oxygen source to the sample water. The oxidation reaction unit 32 includes an ultraviolet lamp 29 that generates ultraviolet rays at the center of the reaction vessel 30, and a heater 31 that adjusts the temperature outside the reaction vessel 30. An air supply mechanism 34 such as a blower for supplying air as an oxygen source is attached to the lower part of the reaction vessel 30 via an electromagnetic valve 33. The oxygen source is not limited to air, and oxygen gas or other mixed gas containing oxygen may be used.

  The sample supply / collection unit 35 of the reaction container 30 supplies the sample water in the sample adjustment tank 21 to the reaction container 30, collects the sample water after the completion of the oxidation reaction, and supplies the sample water to the measurement unit 36. Reference numeral 44 denotes a drain for discharging sample water provided at the bottom of the reaction vessel 30.

The measurement unit 36 measures the absorbance of the molybdenum blue color reaction solution by the sample water after completion of the oxidative decomposition reaction. Although not shown in detail, the measurement unit 36 has a sample cell and a specific wavelength (for example, 880 nm or 710 nm). It comprises a light source that generates light and irradiates the sample cell, a sensor that detects light transmitted through the sample cell, and the like.
The arithmetic processing unit 38 converts the absorbance measured by the measuring unit 36 into a total phosphorus concentration and displays it on the display unit 39.

  42 is an input unit, and the operator inputs the oxidation conditions in the oxidation reaction unit and the amount and concentration of the reagent added to the sample water from the input unit 42, so that the control unit 40 performs control based on the conditions input by the operator. Do. The control unit 40 is a CPU, which is realized by a dedicated microcomputer or a general-purpose personal computer. The operation of switching the port valves 28a and 28b, the operation of the motor 45 that drives the syringe pump 37, and the heating temperature of the reaction vessel 30 by the heater 31. The heating time, the measurement operation of the measurement unit 36, the on / off of the ultraviolet lamp 29, and the air supply operation by the bulb 33 are controlled.

The operation of total phosphorus measurement in the total phosphorus measuring apparatus in this embodiment will be described with reference to the flowchart of FIG.
Before sampling the sample water, the hydrochloric acid solution 26 is allowed to flow through the tube 50 via the port valves 28a and 28b, and then the pure water 27 is allowed to flow into the tube 50 to clean the inside of the tube 50.
The sample water in the sample preparation tank 21 is measured and collected by the syringe pump 37 via the port valves 28a and 28b, and the blank water 27 is sucked into the syringe pump 37 via the port valve 28a and diluted as necessary. Next, as a pretreatment, sulfuric acid 24 is added through the port valve 28a so that the sample water becomes about 1N. Addition of sulfuric acid promotes hydrolysis of condensed phosphoric acid contained in the sample water.

The sample water after completion of the pretreatment is introduced into the reaction vessel 30 heated to about 95 ° C. by the heater 31 through the port valves 28a and 28b.
Subsequently, air as an oxygen source is injected from the air supply mechanism 34 into the sample water at a volume amount about three times that of the sample water per minute, and the sample water is irradiated with ultraviolet rays by the ultraviolet lamp 29 for about 20 minutes. Thereby, the phosphorus compound is oxidatively decomposed to orthophosphoric acid. In this reaction, the oxygen in the injected air is irradiated with ultraviolet rays to become oxygen atoms and ozone, and these oxygen atoms and ozone accelerate the decomposition of the phosphorus compound in the sample water.

  After completion of the oxidation reaction, the air supply and ultraviolet irradiation are stopped, and a certain amount of sample water is measured and collected by the syringe pump 37 via the port valves 28a and 28b, and into the sodium hydroxide solution 25 via the port valve 28a. Then, an ammonium molybdate / antimony potassium tartrate solution 22 and an L-ascorbic acid solution 23 are added, and the sample water is used as a molybdenum blue color reaction solution. The reaction solution is guided to the measurement unit 36 through the port valves 28a and 28b, and the absorbance of light having a wavelength of 880 nm, for example, is measured, and dark correction and zero point correction are performed. The measurement result is taken into the arithmetic processing unit 38. The dilution rate and calibration data of the sample water are input to the arithmetic processing unit 38, and the total phosphorus concentration of the phosphorus compound in the sample water can be obtained based on these data.

  The sample water heating temperature, heating time, air injection amount, sulfuric acid concentration, etc. may be changed depending on the sample water. However, as the set values, the sample water heating temperature is 50 to 100 ° C., and the heating time is 10 minutes to 45. The amount of water injected per minute is 100 to 500% of the volume of sample water per minute, and the concentration of sulfuric acid in the sample water during the oxidation reaction is suitably 0.4 to 2N.

Table 1 shows the results of the presence or absence of acid cleaning of the water sampling tube during continuous measurement of total phosphorus concentration of factory wastewater as a sample using the apparatus of this example.
The total phosphorus concentration without acid cleaning of the water sampling tube was higher than the result of manual analysis by the potassium peroxodisulfate decomposition method (JIS K0102 46.3.1). The measured value at the time of washing was a value that was in good agreement with the manual analysis value. Similar results were obtained both when the sample water was washed after sampling and when it was washed both before and after sampling.
From this, it was found that accurate measurement can be performed by acid cleaning.
Similar results were obtained even when alkaline cleaning was performed instead of acid cleaning. Furthermore, the tube can be more efficiently cleaned by flowing the acid and alkali back and forth.

  It can be used for water quality analyzers such as TOC, total phosphorus, and total nitrogen measuring devices.

It is the schematic which shows one Example. It is a block diagram which shows schematically the structure of the total phosphorus measuring apparatus of one Example. It is a flowchart figure which shows the operation | movement of the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sample water sampling part 2 Water sampling container 2a Sample collection part 2b Homogenizer 4 Partition plate 6 Supply tube 7 Outlet 8,16 Drain pipe 9,15,17 Valve 10 Strainer 12 Sample supply tube 13 Supply tube 14 Stirrer 19 TOC measurement Container 20 Nozzle 21 Sample adjustment tank 22, 23, 24, 25, 26, 27 Reagent or water 28a, 28b Port valve 29 UV lamp 30 Reaction vessel 31 Heater 32 Oxidation reaction part 33 Electromagnetic valve 34 Air supply mechanism 36 Measurement part 37 Syringe Pump 38 Arithmetic processing unit 39 Display unit 40 Control unit 42 Input unit 44 Drain 45 Motor

Claims (1)

Automatic water quality comprising an analysis unit for measuring the concentration of a specific component in sample water, a sample collection unit for supplying sample water to the analysis unit via a sample supply tube, and a control unit for controlling the operation of the sample collection unit In the measuring instrument,
The sample supply tube feeds sample water collected by the sample collection unit to the analysis unit, and allows the sample collection unit and the analysis unit to send cleaning water or a reagent from the analysis unit side to the sample collection unit. Is fixed between
The analysis unit includes a mechanism for flowing a cleaning reagent made of an acid solution or an alkali solution into the sample supply tube,
The sample water sampling unit has a mechanism for discharging the liquid in the sample water sampling unit to the outside,
The automatic control unit for water quality, wherein the control unit controls the washing reagent to flow from the analysis unit to the tube before and / or after sample collection.

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