JP2010044022A - Method and apparatus for continuously monitoring test water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To continuously monitor a concentration of the infinitesimal quantity of a to-be-analyzed material in test water at the high accuracy. <P>SOLUTION: A method includes: the condensation process for separating the test water into concentrated water and permeated water by processing the test water using a reverse osmosis membrane separator 5; the return process for returning a portion of the concentrated water from the condensation process to the upstream of the reverse osmosis membrane separator 5; the analysis process for measuring the concentration of the to-be-analyzed material in the residual concentrated water using a measurement apparatus 10; the calculation process for calculating the concentration of the to-be-analyzed material in the test water from an analysis result of the analysis process; the test water direct measurement process for introducing the test water into the measurement apparatus 10, and directly measuring the concentration of the to-be-analyzed material; and the correction process for correcting a calculated value of the concentration of the to-be-analyzed material by a blank value measured in the direct measurement process. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method and apparatus for continuous monitoring of test water, and in particular, while separating the supplied test water into concentrated water with an increased concentration of the analyte and water with a reduced concentration of the analyte. The present invention relates to a continuous monitoring method and apparatus for continuously measuring the concentration of an analyte in concentrated water in which the analyte is concentrated.

  INDUSTRIAL APPLICABILITY The sample monitoring method and apparatus of the present invention are useful for continuous monitoring analysis of sample water containing trace amounts of analytes such as ultrapure water in the semiconductor industry, electric power / nuclear power industry, pharmaceutical industry, and all other industrial fields. It is.

  In semiconductor manufacturing plants, ultrapure water is used that has been highly purified by removing impurities. Examples of water quality management items of ultrapure water include resistivity, fine particles, viable bacteria, TOC (Total Organic Carbon), dissolved oxygen, silica, cation ions, anion ions, heavy metals, and the like.

  Currently, ultra-pure water continuous analyzers (online monitors) use resistivity meters, fine particle meters, TOC meters, silica meters, dissolved oxygen meters, metal analyzers, and the like. These analyzers have measurable lower limit values. For example, in a metal element monitor, the measurable lower limit values are about 0.1 to 400 μg / L for Na and Ca, and about 10 ng / L for Fe. It is.

  On the other hand, the required water quality of ultrapure water used in the semiconductor industry, the electric power / nuclear power industry, the pharmaceutical industry, etc. has been increasing in recent years. Therefore, in order to perform water quality management with the above-described analyzer using ultrapure water containing an analyte such as a trace amount of metal ions as the test water, the analyte lower limit value of the analyzer is used for the analysis of the analyte in ultrapure water. It is necessary to concentrate to the above concentration. In addition, even in the case of an analysis target substance that is contained above the measurement lower limit value, it may be necessary to concentrate the analysis target substance in order to obtain a more accurate analysis result.

Conventionally, as a method for continuously concentrating and monitoring a substance to be analyzed in ultrapure water, as described in JP-A-2004-77299, a reverse osmosis membrane device and an electrodeionization device are provided in multiple stages. Therefore, a method for highly concentrating the substance to be analyzed has been proposed.
JP 2004-77299 A

  However, in the method of Japanese Patent Application Laid-Open No. 2004-77299, since the reverse osmosis membrane device and the like are provided in at least two stages, the device is increased in size, and thus cannot be put into practical use as a monitoring device. In addition, when ultrapure water containing only a very small amount of each metal ion concentration of 1 ng / L or less is to be concentrated, two stages are insufficient for concentrating to the target concentration, and more devices are used. Since it cannot be concentrated to the target concentration unless it is provided, the apparatus is further increased in size.

  The present invention solves the above-mentioned conventional problems, and even if the amount of the analyte to be analyzed is extremely small, the analyte is continuously concentrated to the target concentration by a small device, and the concentrated analyte It is an object of the present invention to provide a continuous sample monitoring method and apparatus capable of continuously monitoring the concentration of water.

  In particular, an object of the present invention is to provide a method and an apparatus for continuously monitoring sample water in which the concentration of a substance to be analyzed analyzed by an analyzer is corrected by a blank value and sensitivity of the analyzer.

The continuous monitoring method for test water of the present invention (Claim 1) is a method for continuously monitoring the concentration of the analyte in the test water,
A concentration step for separating the sample water into a concentrated water in which the analyte is concentrated and a permeated water in which the concentration of the analyte is reduced by treating the sample water with a reverse osmosis membrane separator;
A return step of returning a part of the concentrated water from the concentration step to the upstream side of the reverse osmosis membrane separation device;
An analysis process for measuring the concentration of the analyte in the remaining concentrated water with a measuring device;
A calculation step of calculating the concentration of the analyte in the test water based on the analysis result of the analysis step;
A test water direct measurement step for directly measuring the analyte concentration by introducing the test water into the measuring device;
And a blank correction step of correcting the concentration of the analyte to be analyzed calculated in the calculation step based on the blank value measured in the water sample direct measurement step.

  The continuous monitoring method of sample water according to claim 2 is the method of continuous monitoring of sample water according to claim 1, wherein in the returning step, the concentrated water is added so that the membrane surface flow rate of the reverse osmosis membrane in the reverse osmosis membrane separation device is 25 to 600 m / Hr. It is characterized by returning.

  The continuous water monitoring method according to claim 3 is the pH adjustment according to claim 1 or 2, wherein the pH of the water introduced into the reverse osmosis membrane separation device is adjusted to be in the range of 3.0 to 6.95. It has the process.

  The continuous monitoring method of sample water according to claim 4 is the method according to any one of claims 1 to 3, wherein the sample water is ultrapure water having a metal ion concentration of each metal of 1 ng / L or less. The target substance is a metal ion.

  The continuous water sampling monitoring method according to claim 5 is characterized in that, in any one of claims 1 to 4, the direct water sample measurement step is performed at the start of the analysis step or at the start of water supply of the water sample. .

  The continuous monitoring method for sample water according to claim 6 is the method according to any one of claims 1 to 5, wherein, in the sample direct measurement step, a part of the sample water is directly supplied to the measuring device. The remaining portion is supplied to the reverse osmosis membrane separation device, and the concentrated water from the reverse osmosis membrane separation device is returned to the upstream side of the reverse osmosis membrane separation device.

The continuous monitoring method of sample water according to claim 7 is the method according to any one of claims 1 to 6,
A sensitivity measuring step of supplying a liquid having a known analyte concentration to the measuring device and measuring the analyte concentration, and measuring the sensitivity of the measuring device according to the measured value in this step;
And a sub-sensitivity correction step of correcting the analyte concentration calculated in the calculation step according to the sensitivity measured in the sensitivity measurement step.

The continuous monitoring method for test water of the present invention (Claim 8) is a method for continuously monitoring the concentration of the analyte in the test water,
A concentration step for separating the sample water into a concentrated water in which the analyte is concentrated and a permeated water in which the concentration of the analyte is reduced by treating the sample water with a reverse osmosis membrane separator;
A return step of returning a part of the concentrated water from the concentration step to the upstream side of the reverse osmosis membrane separation device;
An analysis process for measuring the concentration of the analyte in the remaining concentrated water with a measuring device;
A calculation step of calculating the concentration of the analyte in the test water based on the analysis result of the analysis step;
A sensitivity measuring step in which a liquid having a known analyte concentration is supplied to the measuring device, the analyte concentration is measured, and the sensitivity of the measuring device is measured based on the measured value in this step;
And a sub-sensitivity correction step of correcting the analyte concentration calculated in the calculation step according to the sensitivity measured in the sensitivity measurement step.

The continuous monitoring apparatus for test water of the present invention (Claim 9) is an apparatus for continuously monitoring the concentration of the analyte in the test water.
A reverse osmosis membrane separation device that separates the sample water into a concentrated water in which the analyte is concentrated and a permeated water in which the analyte concentration is reduced by subjecting the test water to reverse osmosis membrane separation;
Return means for returning a part of the concentrated water to the upstream side of the reverse osmosis membrane separation device;
A measuring device for measuring the concentration of the analyte in the remaining concentrated water;
A computing means for computing the concentration of the analyte in the test water based on the analysis result of the measuring device;
A bypass line for directly introducing the test water into the measuring device and measuring the concentration of the analyte,
Blank correction means for correcting the analyte concentration calculated by the calculation means by a blank value when the test water is directly measured by the measuring device,
It is characterized by having.

The continuous water monitoring device of claim 10 according to claim 9,
A known concentration liquid supply means for supplying a liquid with a known analyte concentration to the measuring device;
Sub-sensitivity correction means for calculating the sensitivity of the measurement apparatus based on the measured value of the concentration of the analysis target substance in the known concentration solution measured by the measurement apparatus, and correcting the analysis target substance concentration calculated by the calculation means according to the sensitivity; It is characterized by having.

The continuous monitoring apparatus for test water of the present invention (Claim 11) is an apparatus for continuously monitoring the concentration of the analyte in the test water.
A reverse osmosis membrane separation device that separates the sample water into a concentrated water in which the analyte is concentrated and a permeated water in which the analyte concentration is reduced by subjecting the sample water to a reverse osmosis membrane separation treatment;
Return means for returning a part of the concentrated water to the upstream side of the reverse osmosis membrane separation device;
A measuring device for measuring the concentration of the analyte in the remaining concentrated water;
A computing means for computing the concentration of the analyte in the test water based on the analysis result of the measuring device;
A known concentration liquid supply means for supplying a liquid with a known analyte concentration to the measuring device;
Sub-sensitivity correction means for calculating the sensitivity of the measurement apparatus based on the measured value of the concentration of the analysis target substance in the known concentration solution measured by the measurement apparatus, and correcting the analysis target substance concentration calculated by the calculation means according to the sensitivity; It is characterized by having.

  The continuous monitoring apparatus for sample detection according to claim 12 is such that the pH of water introduced into the reverse osmosis membrane separation device is in the range of 3.0 to 6.95 in any one of claims 9 to 11. It has a pH adjusting means for adjusting to the above.

  In the present invention, even if the reverse osmosis membrane separation device as the concentration means is a single stage, a trace amount analysis in the sample water is performed by circulating a part of the concentrated water and increasing the membrane surface flow velocity of the reverse osmosis membrane. The target substance can be concentrated at a high concentration rate. Further, during the concentration, there is no change in the form of the analyte in the test water, and there is almost no problem of contamination. For this reason, it is possible to accurately and continuously monitor a very small amount of component, which is difficult to analyze by the conventional method, with a small apparatus.

  According to the present invention, a sample water containing a trace amount of an analyte that is less than the measurement lower limit of a measuring device (analyzer), such as ultrapure water, causes a change in the shape of the analyte and contamination of the sample water. In addition, continuous concentration can be performed easily and efficiently with a small device, and continuous analysis can be performed. The analysis efficiency is greatly improved and the time required for analysis is greatly reduced, and the analysis results are operated and managed. It is possible to reflect it early.

  In the present invention, the sample water is directly introduced into the analyzer and measured, and the analytical value of the analyte concentration is corrected by the measured value (blank value) at this time, thereby improving the accuracy of the analytical value of the analyte concentration. To do.

  That is, since the concentration of the analyte in the sample water to be measured in the present invention is extremely low, the true value of the measured value (analyte concentration) when this sample is directly introduced into the analyzer is measured, It becomes almost zero. Actually, the measured water direct measurement value may deviate from 0 and show a blank value due to an error of the analyzer. Therefore, the difference (error) between the measured value of the analyte concentration and the true value of the analyte concentration can be reduced by performing correction (blank correction) to subtract the blank value from the calculated analyte concentration value. it can.

  In the present invention, a liquid having a known analyte concentration is introduced into the analyzer and analyzed, and the measured value at this time is compared with the known concentration value to determine the sensitivity of the analyzer. The calculated value may be corrected. By performing correction according to such sensitivity (subsensitivity correction), the difference (error) between the measured analyte concentration value and the true value of the analyte concentration can be reduced.

  Note that claim 1 is a monitoring method for performing the blank correction.

  Claim 7 is a monitoring method for performing blank correction and sub-sensitivity correction.

  Claim 8 is a monitoring method for performing sub-sensitivity correction.

  Claim 9 is a monitoring device for performing blank correction.

  Claim 10 is a monitoring device that performs blank correction and subsensitivity correction.

  The eleventh aspect is a monitoring device that performs sub-sensitivity correction.

  In general, since the blank value of the measuring device varies due to fluctuations in the flow rate of water flow to the measuring device (analyzer), it is preferable to obtain the blank value at the start of the analysis process or at the start of water supply for the test water.

  In the present invention, when the test water is directly introduced into the analyzer to obtain the blank value, a part of the test water is introduced into the analyzer, and the remainder of the test water is supplied to the reverse osmosis membrane separation device to perform reverse osmosis. It is preferable to continue the operation of the membrane separator. By continuously operating the reverse osmosis membrane separation device in this way, retention of concentrated water in the reverse osmosis membrane separation device is prevented, and contamination (membrane fouling) of the reverse osmosis membrane is prevented.

  In the present invention, contamination of the reverse osmosis membrane can also be prevented by increasing the membrane surface flow velocity in the reverse osmosis membrane separation device to 25 to 600 m / Hr.

  In the present invention, when the concentrated water is circulated by reducing the pH to about 3.0 to 6.95, for example, by adding an acid to the test water, the trace components in the test water are highly concentrated. Even so, precipitation of the analyte is prevented in the reverse osmosis membrane separation device. As a result, the test water can be highly concentrated to obtain an accurate analysis result.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

[First embodiment (only blank correction)]
FIG. 1 is a system diagram showing a first embodiment of the continuous monitoring method and apparatus for test water of the present invention. In this embodiment, blank correction is performed.

  The test water is introduced into the concentration chamber 5a of the reverse osmosis membrane separation device (hereinafter sometimes referred to as “RO device”) 5 through the pipe 1, the line mixer 2 and the pipe 3. The permeated water that has permeated through the reverse osmosis membrane (hereinafter sometimes referred to as “RO membrane”) 5b is discharged from the permeated water chamber 5c through the pipe 6 having the valve 6a. In addition, the acid can be injected into the pipe 1 through the pipe 4 having the chemical injection pump 4a.

  The concentrated water that has flowed out of the concentration chamber 5a of the RO device 5 is circulated through the pipe 3 through the pipe 7 having the circulation pump 7a. A pipe 8 is branched from the middle of the pipe 7, and the concentrated water can be introduced into the measuring device 10 for measuring the concentration of the substance to be analyzed via the valve 8 a and the pipe 9. The measurement wastewater of the measuring device 10 is discharged out of the system.

  The test water supply pipe 1 and the pipe 9 are connected by a pipe 11 having a valve 11 a so that the test water can be directly introduced into the measuring device 10.

  The operation of the monitoring apparatus configured as described above will be described below.

<During monitoring>
At the time of monitoring, as shown in FIG. 1A, the valve 11a is closed, the valves 6a and 8a are opened, and the pumps 4a and 7a are turned on.

  Thus, after adjusting the pH by adding an acid to the test water, it is supplied to the RO device 5 and separated into concentrated water in which the analyte is concentrated and permeated water in which the analyte concentration is reduced. A part of the concentrated water is returned to the water supply pipe 3 of the RO device 5 by the circulation pump 7a. Further, the remaining portion of the concentrated water is supplied to the measuring device 10, the concentration of the analyte in the concentrated water is measured, and this result is input to an arithmetic unit (not shown) consisting of a microcomputer, Calculate the concentration.

  Examples of the acid added to the test water include inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid. The sample water has a pH of 3.0 to 6.95, particularly 6 to 6.95, which is obtained by adding such an acid and flowing into the RO device 5 (hereinafter sometimes referred to as “RO water supply”). It is adjusted to become. In this way, by setting the pH of the RO feedwater to be slightly acidic of 3.0 to 6.95, it is possible to concentrate a very small amount of the analyte in the test water at a high concentration rate in the RO device 5. . This is due to the effect of preventing the deposition by ionizing a metal that is easily deposited by forming a hydroxide by making the test water weakly acidic. If this adjusted pH value exceeds the above upper limit value, the above effect cannot be sufficiently obtained, and if it is less than the above lower limit value, there is a possibility of causing performance deterioration of components such as the RO membrane 5b.

  As the concentration ratio in the RO device 5 (in FIG. 1, the ratio between the amount of test water introduced into the system and the amount of concentrated water supplied to the measuring device 10) is larger, the analyte in the test water is highly concentrated in the concentrated water. Therefore, although the analysis accuracy in the measuring apparatus 10 is improved, if the concentration is excessively high, the concentration of the analysis target substance in the concentrated water increases, and the analysis target substance may be deposited on the RO membrane surface and cannot be recovered. In order to increase the concentration rate, it is necessary to increase the capacity of the reverse osmosis membrane separation device. Therefore, the concentration rate of the RO device 5 should be 2 to 2000 times, particularly about 10 to 100 times, and the concentration of the analyte in the concentrated water should be 2 to 3 times the measurement lower limit value of the measuring device 10. preferable.

  The concentrated water is preferably circulated so that the membrane surface flow velocity at the RO membrane is 25 to 600 m / Hr, particularly 400 to 450 m / Hr. Thus, by increasing the membrane surface flow velocity in the RO membrane, the concentration polarization on the membrane surface is reduced, and metal adhesion to the membrane surface is suppressed.

  As the circulation pump 7a for circulating the concentrated water, a member employing a member made of a fluororesin (including a fluororesin processed product) such as polytetrafluoroethylene is suitable. Further, as the pump type, a magnetic levitation type pump or the like in which no contact between members by a motor is preferable.

  There is no restriction | limiting in particular as the measuring apparatus 10, Although it determines suitably according to the kind of analysis object substance, an ion chromatograph or a spectrophotometer is suitable for the analysis of a metal ion. In addition, a resistivity meter, a fine particle meter, a TOC meter, a silica meter, a dissolved oxygen meter and the like can also be used. A plurality of measuring devices may be used. In this case, these may be arranged in series or in parallel.

  In addition, there is no restriction | limiting in particular in the RO membrane used for concentration of test water.

  In the present invention, it is possible to provide the RO device in two or more stages, but according to the present invention, the test water can be sufficiently concentrated by the one-stage RO device, and the monitoring device is small. For the purpose of realizing, the RO device is usually provided with only one stage.

  There are no particular restrictions on the sample water to be monitored, but in general, the concentration of the analyte is low, and concentration is required for water quality analysis. Examples include ultrapure water used in factories and the like.

  Examples of the analytes that can be monitored include cations, silica, metals, organic acids and the like when an ion chromatograph is used as an analysis means. In addition, when a spectrophotometer is used as the analysis means, cations, silica, heavy metals, and the like can be given.

  The present invention is particularly effective when continuously monitoring the metal ion concentration of ultrapure water in which the metal ion concentration of each metal is 1 ng / L or less.

  From the concentration of the analyte in the concentrated water analyzed by the measuring device 10, the concentration of the analyte in the test water can be calculated as follows.

  That is, as in the present invention, when the sample water is continuously concentrated by the RO membrane and a part of the concentrated water is circulated, the flow rate of the sample water in the system is stable in a substantially steady state. If the sample water flow rate, circulating water volume, and concentrated water withdrawal volume are kept constant, the concentration rate at the RO membrane can be considered to be constant, and the concentration of the analyte in the concentrated water is as follows: The value obtained by dividing the value by the concentration factor can be used as the calculated value of the concentration of the analyte to be analyzed.

Supply amount of test water to RO device: Ff
Concentrated water amount to be extracted out of the system (in FIG. 1, the amount of concentrated water discharged out of the system via the measuring device 10): Fb
Concentration of analyte in concentrated water (monitoring detection value): Cm
Concentration ratio of RO device: Ff / Fb
Analytical substance concentration calculation value X _{m in the} sample water
= Analyte concentration of concentrated water / concentration ratio = Cm / (Ff / Fb)

In one aspect of the present invention, the blank value X ₀ from the calculation value X _m of the analyte concentration by subtracting to the analyte concentration blank correction. That is, the concentration of the analysis target substance (blank correction value) X = X _m −X ₀
It is. The blank value X ₀ is determined by the following test water direct measurement step.

<Test water direct measurement process (blank value measurement)>
In order to obtain the blank value, the valve 11a is opened and the valve 8a is closed as shown in FIG. 1 (b), a part of the test water is branched from the pipe 1 to the pipe 11, and the test water is supplied to the measuring device 10. Introduce directly and measure the analyte concentration in the test water. Since the concentration of the substance to be analyzed in the test water is extremely low, the true value of the measured value by the measuring device 10 is substantially 0 (zero). Therefore, the measurement value X ₀ of the measuring device 10 at the time of direct measurement of this test water is the error value of the measuring device 10, the blank value.

Therefore, by subtracting the blank value _{(X 0)} from the calculated value _{X m} according to _{X =} X m -X _0, blank-corrected concentration X is obtained. If X ₀ is a positive value, the corrected analyte value X is smaller only X ₀ than calculating the concentration X _m, if X ₀ is a negative value, the corrected analyte value X operation thus greater by -X ₀ than the concentration _{X m.}

In this case measuring the blank value X _0, as Fig. 1 (b), the remainder of the test water from the pipe 1 by adding an acid in the same manner as FIG. 1 (a), supplied to the RO apparatus 5 And circulate the concentrated water. Thereby, the retention of the concentrated water in the RO device 5 is prevented, and contamination of the RO membrane 5b is prevented. When the blank value measurement operation in FIG. 1 (b) returns to the monitoring operation in FIG. 1 (a), monitoring can be resumed promptly based on the measurement value of the measuring device 10.

<Water flow method during maintenance of measuring device 10>
When the measuring device 10 is maintained (maintenance / inspection; hereinafter abbreviated as “maintenance”), both the valves 8a and 11a are closed and the water supply to the measuring device 10 is stopped as shown in FIG.

  Also during this maintenance, acid is added to the test water, the water is passed through the RO device 5, and the concentrated water is circulated to prevent contamination of the RO membrane 5b.

<Example of monitoring in ultrapure water production equipment>
An example of the operation flow when this monitoring device is applied to the ultrapure water monitoring of the ultrapure water production device is shown below.

<Water supply from ultrapure water production equipment stops during monitoring and then resumes>
Step 0: As shown in FIG. 1 (a), the valve 8a is opened and the valve 11a is closed to perform continuous monitoring operation.
Step 1: When the supply of test water to the continuous monitoring device is stopped along with the initial startup and maintenance of the ultrapure water production apparatus, the supply of test water is stopped, so that the pumps 4a and 7a are stopped.
Step 2: When the supply of test water to the continuous monitoring apparatus starts (restarts) with the start (restart) of the operation of the ultrapure water production apparatus, the supply of test water starts (restarts), so the pump 4a , 7a starts (restarts). It is confirmed that the concentration / circulation in the RO device 5 of the sample water has reached a steady state.
Step 3: as Fig. 1 (b), the valve 8a closed, and the valve 11a is opened, is introduced directly into the test water in the measuring device 10 for measuring a blank value X _0.
Step 4: as 1 (a), the valve 8a opens, and the valve 11a closed, to introduce the concentrated water to the measuring device 10 measures the analyte concentration C _m of the concentrate water.
Step 5: Based on the C _m and RO concentration ratio calculating a target substance concentration X _m of test water, to correct the calculated value X _m by the blank value X _0.
Step 6: Return to step 0.

<Maintenance of measuring apparatus 10 and reagent replacement>
Step 10: As shown in FIG. 1 (a), the valve 8a is opened and the valve 11a is closed, and the continuous monitoring operation is performed.
Step 11: The valve 8a is closed to stop water supply to the measuring device 10, and maintenance of the measuring device 10 and reagent replacement are performed. At this time, concentration / circulation in the RO device 5 of the test water is continued.
Step 12: As Fig. 1 (b), the valve 11a is opened, the valve 8a is kept closed, and directly introduced into the test water in the measuring device 10 for measuring a blank value X _0.
Step 13: As FIG. 1 (a), the valve 8a opens, and the valve 11a closed, to introduce the concentrated water to the measuring device 10 measures the analyte concentration C _m of the concentrate water.
Step 14: Based on the _{C m} and RO concentration ratio calculating a target substance concentration _{X m} of test water, to correct the calculated value _{X m} by the blank value _{X 0.}
Step 15: Return to Step 10.

[Second Embodiment (Blank and Secondary Sensitivity Correction)]
FIG. 2 is a system diagram showing a second embodiment of the continuous monitoring method and apparatus for detecting water according to the present invention. In this embodiment, both blank correction and subsensitivity correction are performed.

  In this embodiment, a standard solution made of an analyte-containing liquid having a known concentration can be injected downstream of the valve 11a of the pipe 11 through the pipe 12 having the pump 12a. A line mixer 13 is provided in the pipe 11 on the downstream side of the injection point.

  A pipe 9 for supplying concentrated water to the measuring device 10 is provided with a four-way valve 14 so that the concentrated water can be supplied to the measuring device 10 via the four-way valve 14.

  The pipe 11 is connected to the four-way valve 14, and water from the pipe 11 can be supplied to the measuring device 10 through the four-way valve 14. A drainage pipe 15 is connected to the four-way valve 14.

  Other configurations are the same as those in FIG. 1, and the same reference numerals denote the same parts.

  The operation of this monitoring device will now be described.

<During monitoring>
At the time of monitoring, the valves 11a and 8a are opened as shown in FIG. The four-way valve 14 is selected so that the concentrated water is guided to the measuring device 10 and the test water from the pipe 11 is guided to the pipe 15.

  The standard solution injection pump 12a is stopped.

  By introducing the concentrated water into the measuring device 10, monitoring is performed in the same manner as in FIG. In addition, the measurement result of the measuring apparatus 10 is corrected as described later.

<Test water direct measurement process (blank value measurement)>
In order to obtain a blank value, the four-way valve 14 is switched as shown in FIG. 2 (b), the concentrated water is discharged from the pipe 8 through the pipe 15, and the test water separated from the pipe 1 into the pipe 11 is collected. It is introduced directly into the measuring device 10.

Thus, the blank value X ₀ in the same manner as in the first diagram (b) is obtained.

  Even in the case of FIG. 2 (b), the pumps 4a and 7a are operated to add acid and circulate concentrated water to prevent the RO membrane 5b from being contaminated.

<Sensitivity measurement>
In order to perform sensitivity measurement of the measuring apparatus 10, a standard solution with a known analyte concentration is quantitatively added to the pipe 11 as shown in FIG. The sample water flow rate of the pipe 11 is previously measured with a flow meter (not shown).

  Note that when the operation of the ultrapure water production apparatus is in a steady state, the flow rate of the test water is constant, and the flow rate of the test water flowing through the pipe 11 is also constant. This flow rate can be adjusted by the opening degree of the valve 11a.

The flow path selection of the four-way valve 14 is the same as in FIG. 2 (b), and the standard solution added test water from the pipe 11 is introduced into the measuring device 10. The analysis target substance concentration of the standard solution added test water is calculated from the amount of the standard solution added from the pipe 12 and the test water flow rate of the pipe 11. The ratio X ₂ / X ₁ of the measured concentration X ₂ of the measuring apparatus 10 to the calculated analysis target substance concentration X _{1 is} defined as sensitivity.

By correcting the analyte concentration X _m computed from the detected values of the measuring device 10 at the time of monitoring of FIG. 2 (a) according to the following equation, the blank value and analyte concentration X, which is corrected by the sensitivity 'is Desired.

X ′ = (X _m −X ₀ ) / (X ₂ / X ₁ )
Although corrected by a blank value X ₀ and sensitivity X _m in this embodiment _(X 2 _/ X _1), it may be corrected only in sensitivity. That is, X ₀ = 0 may be set.

Step in the case of performing the operation of the monitoring apparatus shown in FIG. 2 on the basis of both the blank value X ₀ and sensitivity (X 2 _{/ X 1),} the constant monitoring (FIG. 2 (a)) → blank value measurement (a 2 (b)) → sensitivity measurement (FIG. 2 (c)) → steady monitoring (FIG. 2 (a)).

  Each of the above embodiments is an example of the present invention, and the present invention may be configured other than illustrated.

  For example, a three-way valve may be used instead of the two-way valves 8a and 11a. Further, the two-way valves 8a and 11a may be automatically controlled. Also in FIG. 1, the four-way valve 14 and the pipe 15 may be provided, and the concentrated water may be discharged from the pipe 15 at the time of blank value measurement (FIG. 1 (b)).

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

  In the following Examples and Comparative Examples, continuous monitoring of sample water was performed using the apparatus shown in FIG.

  As the RO membrane 5b of the RO device 5, a reverse osmosis membrane “ES-20-D4” (4 inch) manufactured by Nitto Denko Corporation is used, and as a circulating pump 7a for concentrated water of the RO membrane 5b, Levitro magnetic levitation manufactured by Iwaki Corporation is used. A mold pump “LEV300F” (maximum discharge rate 40 L / min, maximum lift 20 m, maximum rotation speed 6200 rpm, withstand pressure 0.30 MPa) was used. As the measuring apparatus 10, a spectrophotometer “FIAMO” manufactured by FIAMO was used.

  Ultrapure water (pH 7.0) was used as test water, and trace amounts of Fe ions in ultrapure water were monitored and analyzed, and Fe ions were measured with a spectrophotometer.

[Example 1]
The RO device 5 was supplied with ultrapure water adjusted to pH 6.5 by adding nitric acid at 500 mL / min, and circulated 50 mL / min (10-fold concentration) of concentrated water. At this time, the membrane surface flow velocity of the RO membrane 5b is 427 m / Hr.

  After performing the monitoring of FIG. 1 (a) for 30 minutes, the blank value measurement of FIG. 1 (b) was performed for 30 minutes, and this was repeated. And the calculation value at the time of monitoring was correct | amended with the blank value, and the result was shown in FIG. During the monitoring, the state shown in FIG. 1 (c) was changed for 60 minutes for reagent replacement, and then the monitoring was resumed.

[Comparative Example 1]
In Example 1, the blank value was not acquired, and the concentration of the analysis target substance was calculated from the measured value from the measuring device 10. As in Example 1, the state shown in FIG. 1 (c) was maintained for 60 minutes for reagent replacement during monitoring, and then monitoring was resumed. The results are shown in FIG.

  As shown in FIG. 3, according to Example 1, it can be seen that the concentration of the analyte in the test water is constant without fluctuation. On the other hand, in Comparative Example 1, it is recognized that the calculated value of the analyte concentration varies when the state of FIG. 1 (c) is taken.

  As is clear from the above results, according to the present invention, it is possible to obtain a highly accurate analysis result by continuously highly concentrating a trace amount of an analyte of 1 ng / L or less in test water.

It is a systematic diagram which shows the continuous monitoring apparatus of the test water which concerns on embodiment. It is a systematic diagram which shows the continuous monitoring apparatus of the test water which concerns on another embodiment. It is a graph which shows the measured value of the metal ion in Example 1 and Comparative Example 1.

Explanation of symbols

2,13 Line mixer 5 Reverse osmosis membrane separation device (RO device)
10 Measuring device 14 Four-way valve

Claims (12)

In the method of continuously monitoring the concentration of the analyte in the sample water,
A concentration step for separating the sample water into a concentrated water in which the analyte is concentrated and a permeated water in which the concentration of the analyte is reduced by treating the sample water with a reverse osmosis membrane separator;
A return step of returning a part of the concentrated water from the concentration step to the upstream side of the reverse osmosis membrane separation device;
An analysis process for measuring the concentration of the analyte in the remaining concentrated water with a measuring device;
A calculation step of calculating the concentration of the analyte in the test water based on the analysis result of the analysis step;
A test water direct measurement step for directly measuring the analyte concentration by introducing the test water into the measuring device;
And a blank correction step of correcting the analyte concentration calculated in the calculation step based on the blank value measured in the sample direct measurement step.   2. The continuous monitoring of the test sample according to claim 1, wherein in the returning step, the concentrated water is returned so that a membrane surface flow velocity of the reverse osmosis membrane in the reverse osmosis membrane separation device is 25 to 600 m / Hr. Method.   3. The continuous water test according to claim 1, further comprising a pH adjustment step of adjusting the pH of water introduced into the reverse osmosis membrane separation device to be in a range of 3.0 to 6.95. Monitoring method.   4. The sample water according to claim 1, wherein the sample water is ultrapure water having a metal ion concentration of each metal of 1 ng / L or less, and the analysis target substance is a metal ion. Continuous monitoring method of sample water.   5. The continuous test water monitoring method according to claim 1, wherein the test water direct measurement step is performed at the start of the analysis step or at the start of water supply of the test water.   In any 1 item | term of the Claim 1 thru | or 5, in the said test water direct measurement process, a part of test water is directly supplied to the said measuring apparatus, and the remainder of test water is supplied to the said reverse osmosis membrane separator. A method for continuously monitoring water sample, wherein the concentrated water from the reverse osmosis membrane separation device is returned to the upstream side of the reverse osmosis membrane separation device. In any one of Claims 1 thru | or 6,
A sensitivity measuring step of supplying a liquid having a known analyte concentration to the measuring device and measuring the analyte concentration, and measuring the sensitivity of the measuring device according to the measured value in this step;
A method for continuously monitoring water sample, comprising: a sub-sensitivity correction step for correcting the analyte concentration calculated in the calculation step according to the sensitivity measured in the sensitivity measurement step. In the method of continuously monitoring the concentration of the analyte in the sample water,
A concentration step for separating the sample water into a concentrated water in which the analyte is concentrated and a permeated water in which the concentration of the analyte is reduced by treating the sample water with a reverse osmosis membrane separator;
A return step of returning a part of the concentrated water from the concentration step to the upstream side of the reverse osmosis membrane separation device;
An analysis process for measuring the concentration of the analyte in the remaining concentrated water with a measuring device;
A calculation step of calculating the concentration of the analyte in the test water based on the analysis result of the analysis step;
A sensitivity measuring step in which a liquid having a known analyte concentration is supplied to the measuring device, the analyte concentration is measured, and the sensitivity of the measuring device is measured based on the measured value in this step;
A method for continuously monitoring water sample, comprising: a sub-sensitivity correction step for correcting the analyte concentration calculated in the calculation step according to the sensitivity measured in the sensitivity measurement step. In a device that continuously monitors the concentration of the analyte in the sample water,
A reverse osmosis membrane separation device that separates the sample water into a concentrated water in which the analyte is concentrated and a permeated water in which the analyte concentration is reduced by subjecting the test water to reverse osmosis membrane separation;
Return means for returning a part of the concentrated water to the upstream side of the reverse osmosis membrane separation device;
A measuring device for measuring the concentration of the analyte in the remaining concentrated water;
A computing means for computing the concentration of the analyte in the test water based on the analysis result of the measuring device;
A bypass line for directly introducing the test water into the measuring device and measuring the concentration of the analyte,
Blank correction means for correcting the analyte concentration calculated by the calculation means by a blank value when the test water is directly measured by the measuring device,
A continuous monitoring device for sample water characterized by comprising: In claim 9,
A known concentration liquid supply means for supplying a liquid with a known analyte concentration to the measuring device;
Sub-sensitivity correction means for calculating the sensitivity of the measurement apparatus based on the measured value of the concentration of the analysis target substance in the known concentration solution measured by the measurement apparatus, and correcting the analysis target substance concentration calculated by the calculation means according to the sensitivity; A continuous monitoring device for sample water characterized by comprising: In a device that continuously monitors the concentration of the analyte in the sample water,
A reverse osmosis membrane separation device that separates the sample water into a concentrated water in which the analyte is concentrated and a permeated water in which the analyte concentration is reduced by subjecting the sample water to a reverse osmosis membrane separation treatment;
Return means for returning a part of the concentrated water to the upstream side of the reverse osmosis membrane separation device;
A measuring device for measuring the concentration of the analyte in the remaining concentrated water;
A computing means for computing the concentration of the analyte in the test water based on the analysis result of the measuring device;
A known concentration liquid supply means for supplying a liquid with a known analyte concentration to the measuring device;
Sub-sensitivity correction means for calculating the sensitivity of the measurement apparatus based on the measured value of the concentration of the analysis target substance in the known concentration solution measured by the measurement apparatus, and correcting the analysis target substance concentration calculated by the calculation means according to the sensitivity; A continuous monitoring device for sample water characterized by comprising:   In any one of Claims 9 thru | or 11, It has a pH adjustment means to adjust so that pH of the water introduce | transduced into the said reverse osmosis membrane separator may be in the range of 3.0-6.95. Continuous monitoring device for sample water.

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