JP2024063135A - Cod/bod sampling amount determination method, automatic dilution device and bod automatic measurement device - Google Patents

Abstract

To provide a COD/BOD sampling amount determination method, an automatic dilution device and a BOD automatic measurement device which determine an appropriate sampling amount in COD analysis and BOD analysis, and can support validity of an analysis result.SOLUTION: A BOD sampling amount determination method includes a step of measuring absorbency of a sample using a UV absorptiometer in the process of co-washing the sampling line with the sample, and a step of determining a sampling amount V (mL) from a BOD prediction value EBOD(mg/L) of a sample calculated using a correlation between absorbency of a previously acquired sample and BOD, the expression (3) and the expression (4) below. V=A×v/EBOD...(3) A=5.0...(4) where A is the median (mg/L) of the dissolved oxygen consumption of the diluted sample (D1-D2), and V is the volume of the diluted sample (mL).SELECTED DRAWING: Figure 2

Description

The present invention relates to the amount of sample taken in COD and BOD analysis, an automatic BOD sample dilution device, an automatic COD measurement device, and an automatic BOD measurement device.

JIS K 0102 specifies the industrial wastewater testing method, and section 17 specifies "oxygen consumption by potassium permanganate at 100°C (COD _Mn )". The following problems have been pointed out regarding the analysis of COD based on section 17 of JIS K 0102 and the COD automatic analyzer.

When hydroxylamine compounds (NS compounds) coexist in the wastewater, it takes about a week to decompose the NS compounds (see, for example, Patent Document 1). The silver chloride that is produced adheres to the inner walls of the reaction tank and piping, and to various sensors such as the oxidation-reduction potential (ORP) electrodes in the reaction tank, causing errors in the measurement of the COD value (see, for example, Patent Document 2). Further issues include the following:

JP 2008-76338 A JP 2009-139119 A

Currently, the amount of sample to be collected in COD analysis is determined by the analyst based on visual predictions of the COD value, such as the turbidity, color, and odor of the sample liquid, and, if the same sample has been analyzed previously, on the actual values from that analysis, as well as other items such as the suspended solids (SS) value. Meanwhile, JIS K 0102, Section 17 specifies that the amount to be collected should be "an amount such that after 30 minutes of heating, the residual volume of a 5 mmol/L potassium permanganate solution is 4.5 to 6.5 mL."

When predictions are based on human senses, if the prediction is wrong and the sample volume is incorrect, the COD value cannot be analyzed correctly, and the sample volume must be adjusted and retested. Even if reanalysis is avoided because the predicted value was correct, the validity of whether the COD value was tested correctly cannot be proven, so analysts must conduct another analysis to confirm the COD analysis value.

Regarding biochemical oxygen demand (BOD), JIS K 0102, section 21 stipulates the amount of sample to be taken. It states that "The BOD value is calculated using the results of a diluted sample in which the amount of dissolved oxygen consumed during five days of cultivation is 40-70% of the amount before cultivation." This shows the importance of the dilution rate.

Currently, the dilution rate for BOD is determined based on the analyst's senses and the transparency of the sample liquid. The validity of whether the BOD value is being tested correctly is the same as for COD.

As described above, the amount of sample taken in COD and BOD analysis has a significant impact on the results, yet no method or device has been developed to automatically take an appropriate amount of sample. Furthermore, no method has been developed to resolve the issue of whether COD and BOD values are being tested correctly.

The object of the present invention is to provide a method for determining the appropriate sample amount for COD and BOD analysis, an automatic dilution device, and an automatic BOD measurement device that can verify the validity of the analysis results.

The present invention is a method for determining a BOD sample collection amount, which includes the steps of measuring the absorbance of the sample using a UV absorptiometer during the process of co-washing the sample collection line with the sample, and determining the sample collection amount V (mL) from the sample's predicted BOD value E _BOD (mg/L) calculated using the correlation between the sample's absorbance and BOD, and equations (3) and (4).
V = A × v / E _BOD ... (3)
A = 5.0 ... (4)
Here, A is the median (mg/L) of the dissolved oxygen consumption (D ₁ -D ₂ ) of the diluted sample.
v is the volume of the diluted sample (mL)

The present invention is an automatic dilution device comprising a UV absorptiometer having a flow cell attached midway through a sampling line for measuring the absorbance of a sample, a sampling amount determination means for determining an appropriate sampling amount V (mL) of the sample defined by an official method from a predicted BOD value E _BOD (mg/L) of the sample calculated using the correlation between the absorbance and BOD of the sample and a relational equation between the predicted BOD value E _BOD (mg/L) defined by an official method and the appropriate amount of sample, an automatic sample sampling means for automatically sampling the sample amount V (mL) determined by the sampling amount determination means, a diluted sample preparation means for adding dilution water to the sampled sample to prepare diluted samples with different dilution ratios and filling them into frank bottles, and a control device for controlling the operation of the equipment and each means, wherein the control device controls the UV absorptiometer so as to measure absorbance during the process in which the sample is delivered and the sampling line is co-washed.

The automatic dilution device according to the present invention is characterized in that the relationship between the BOD predicted value E _BOD (mg/L) defined by the official method and the appropriate amount of sample is expressed by the following formulas (3) and (4).
V = A × v / E _BOD ... (3)
A = 5.0 ... (4)
Here, A is the median (mg/L) of the dissolved oxygen consumption (D ₁ -D ₂ ) of the diluted sample.
V is the sample volume (mL)
v is the volume of the diluted sample (mL)

The present invention is an automatic BOD measurement device that is characterized by comprising the automatic dilution device, a BOD analysis device that includes a dissolved oxygen measurement means for measuring the dissolved oxygen in the diluted sample and a thermostatic chamber for storing the flask, and a control device that controls the operation of the BOD analysis device.

The BOD automatic measurement device according to the present invention comprises a data storage means for storing BOD data linking the absorbance of the sample measured by the UV absorptiometer with the BOD of the sample measured by the BOD analyzer, and a correction means for correcting the correlation between the absorbance and BOD of the sample obtained in advance using the BOD data, and the sample collection amount determination means determines the sample collection amount V using the correlation between the corrected absorbance and BOD of the sample.

The present invention is a method for determining a COD sample collection amount, which comprises the steps of: measuring the absorbance of the sample using a UV absorptiometer during the process of co-washing the sample collection line with the sample; and determining the sample collection amount V (mL) from the predicted COD value E _COD (mg/L) of the sample calculated using the correlation between the sample absorbance and COD, and equations (1) and (2).
V = 0.2 × (a - b) × f × 1000 / E _COD ... (1)
a-b=4.5... (2)
However, when V≧100, V=100
Here, a-b is the median of the titration value (titration amount - blank test value) (mL).
f is the factor of 5 mmol/L potassium permanganate solution

The present invention provides a method for determining the appropriate sample amount for COD and BOD analysis, an automatic dilution device, and an automatic BOD measurement device that can verify the validity of the analysis results.

1 is a diagram showing the procedure of a method for determining a COD sample collection amount according to a first embodiment of the present invention and the relationship between the absorbance of a sample and COD. FIG. 11 is a diagram showing the procedure of a method for determining a BOD sample collection amount according to a second embodiment of the present invention and the relationship between the absorbance of a sample and the BOD. FIG. FIG. 11 is a configuration diagram of a COD automatic measurement device 1 according to a third embodiment of the present invention. FIG. 11 is a configuration diagram of an automatic dilution device 100 according to a fourth embodiment of the present invention. FIG. 11 is a configuration diagram of a BOD automatic measurement device 2 according to a fifth embodiment of the present invention.

Fig. 1 is a diagram showing the procedure of the method for determining the COD sample collection amount according to the first embodiment of the present invention, and the relationship between the absorbance of the sample and the COD. The method for determining the COD sample collection amount according to the first embodiment of the present invention is a method for determining the sample collection amount to realize "the _appropriate amount of sample is an amount such that the residual amount of 5 mmol/L potassium permanganate solution after heating for 30 minutes is 4.5 to 6.5 mL" as specified in JIS K 0102-17 "oxygen consumption by potassium permanganate at 100°C (COD Mn)", and includes a step (A1) of measuring the absorbance of the sample as shown in Fig. 1(A) and a step (A2) of determining the sample collection amount V (mL) from the predicted COD value E _COD (mg/L) of the sample and formulas (1) and (2).

Hereinafter, the method specified in JIS K 0102, Section 17 "Oxygen consumption by potassium permanganate at 100°C (COD _Mn )" will be referred to as the official method, and the appropriate amount of sample for the official method will be the amount specified in the official method, "such that the residual amount of 5 mmol/L potassium permanganate solution after heating for 30 minutes is 4.5 to 6.5 mL."

In step (A1), the absorbance of the sample is measured using a UV spectrophotometer, by irradiating the sample with light having a wavelength of 254 nm and measuring the absorbance. The UV spectrophotometer and the method for measuring the absorbance are not particularly limited, and any known UV spectrophotometer and measurement method can be used.

In step (A2), the sample collection volume V (mL) is determined from the predicted COD value E _COD (mg/L) of the sample and formulas (1) and (2). The predicted COD value E _COD (mg/L) of the sample is calculated using the absorbance of the sample measured in step (A1) and a correlation between the absorbance and COD of the sample obtained in advance. An example of this correlation is shown in Figure 1 (B).

The horizontal and vertical axes of Fig. 1(B) are the absorbance of the sample measured with a UV absorptiometer using light with a wavelength of 254 nm, and the COD (mg/L) obtained by analyzing the sample by an official method. Fig. 1(B) plots the absorbance and COD obtained by measuring a number of samples, and it can be seen that the COD is directly proportional to the absorbance. This is the correlation between the absorbance and COD of the sample obtained in advance, and the predicted COD value E _COD (mg/L) of the sample is obtained by applying the absorbance X obtained in step (A1) to the above correlation. The correlation between the absorbance and COD of the sample can be expressed by a correlation formula as shown in Fig. 1(B), but it may also be expressed by other methods.

In Fig. 1 (B), the absorbance and COD of samples are obtained and plotted using samples of different types, such as wastewater type and discharge location, but the correlation between absorbance and COD may be derived for each specific sample, such as wastewater discharged from the same factory or wastewater discharged from the same location in the same factory. By deriving the correlation between absorbance and COD of a specific sample and using the correlation corresponding to that sample, a highly accurate COD predicted value E _COD (mg/L) can be obtained. Also, a simulated sample may be prepared using a standard substance, and the correlation between absorbance and COD may be obtained from the simulated sample.

Equations (1) and (2) are used to calculate the sample collection volume V (mL) based on the predicted COD value E _COD (mg/L) of the sample, as shown below: Equations (1) and (2) are also shown in the official method.
V = 0.2 × (a - b) × f × 1000 / E _COD ... (1)
a-b=4.5... (2)
However, when V≧100, V=100
Here, a-b is the median of the titration value (titration amount - blank test value) (mL).
f is the factor of 5 mmol/L potassium permanganate solution

The basis for a-b in formula (2) is as follows. According to the official method, the appropriate amount of sample is one in which 10 mL of 5 mmol/L potassium permanganate solution is added to the sample and the remaining amount of 5 mmol/L potassium permanganate solution after heating for 30 minutes is 4.5-6.5 mL, so the amount of 5 mmol/L potassium permanganate solution consumed (titration value) at this time is 3.5-5.5 mL. a-b is the median value of this consumption (titration value), 4.5 mL.

As described above, the method for determining the amount of COD sample to be collected in the first embodiment of the present invention utilizes the correlation between the absorbance of a sample measured using a UV absorptiometer with light of a wavelength of 254 nm and the COD (mg/L) of the sample obtained by analysis using an official method, and from this obtains a predicted COD value E _COD (mg/L) of the sample to determine the amount of sample to be collected.

Fig. 2 is a diagram showing the procedure of the method for determining the BOD sample collection amount according to the second embodiment of the present invention, and the relationship between the absorbance and BOD of the sample. The method for determining the BOD sample collection amount according to the second embodiment of the present invention is a method for determining the sample collection amount to realize the requirement in JIS K 0102, 21 "Biochemical oxygen consumption (BOD)" that "the amount of dissolved oxygen consumed by a diluted sample to obtain a normal BOD of the sample (D ₁ -D ₂ ) is in the range of O 3.6 to 6.4 mg/L", and includes a step (B1) of measuring the absorbance of the sample as shown in Fig. 2(A) and a step (B2) of determining the sample collection amount V (mL) from the predicted BOD value E _BOD (mg/L) of the sample and formulas (3) and (4).

Hereinafter, the method specified in JIS K 0102, Section 21 "Biochemical oxygen consumption (BOD)" will be referred to as the official method, and the appropriate amount of sample that satisfies the official method's specified requirement that "the amount of dissolved oxygen consumed by a diluted sample to obtain a normal BOD for the sample (D ₁ -D ₂ ) is in the range of O 3.6 to 6.4 mg/L" will be referred to as the appropriate amount of sample for the official method.

In step (B1), the absorbance of the sample is measured using a UV spectrophotometer, by irradiating the sample with light having a wavelength of 254 nm and measuring the absorbance. The UV spectrophotometer and the method for measuring the absorbance are not particularly limited, and any known UV spectrophotometer and measurement method can be used.

In step (B2), the sample collection volume V (mL) is determined from the predicted BOD value E _BOD (mg/L) of the sample and equations (3) and (4). The predicted BOD value E _BOD (mg/L) of the sample is calculated using the absorbance of the sample measured in step (B1) and a correlation between the absorbance and BOD of the sample obtained in advance. An example of this correlation is shown in Figure 2 (B).

The horizontal and vertical axes of Fig. 2(B) are the absorbance of the sample measured with a UV absorptiometer using light with a wavelength of 254 nm, and the BOD (mg/L) obtained by analyzing the sample by the official method. Fig. 2(B) plots the absorbance and BOD obtained by measuring a number of samples, and it can be seen that the BOD is directly proportional to the absorbance. This is the correlation between the absorbance and BOD of the sample obtained in advance, and the predicted BOD value E _BOD (mg/L) of the sample is obtained by applying the absorbance X obtained in step (B1) to the above correlation. The correlation between the absorbance and BOD of the sample can be expressed by a correlation formula as shown in Fig. 2(B), but it may also be expressed by other methods.

2(B) shows a plot of absorbance and BOD of samples obtained using samples of different types, such as wastewater type and discharge location, but the correlation between absorbance and BOD for each specific sample, such as wastewater discharged from the same factory or wastewater discharged from the same location in the same factory, may be derived. By deriving the correlation between absorbance and BOD of a specific sample and using the correlation corresponding to that sample, a highly accurate BOD predicted value E _BOD (mg/L) can be obtained. Also, a simulated sample may be prepared using a standard substance, and the correlation between absorbance and BOD may be obtained from the simulated sample.

Equations (3) and (4) are used to calculate the sample collection volume V (mL) based on the predicted BOD value E _BOD (mg/L) of the sample, as shown below: Equations (3) and (4) are also shown in the official method.
V = A × v / E _BOD ... (3)
A = 5.0 ... (4)
Here, A is the median (mg/L) of the dissolved oxygen consumption (D ₁ -D ₂ ) of the diluted sample.
v is the volume of the diluted sample (mL)

The basis for A in formula (4) is as follows: According to the official method, the amount of dissolved oxygen consumed by a diluted sample (D ₁ -D ₂ ) to obtain a normal BOD for the sample is in the range of O 3.6 to 6.4 mg/L, so the median value of the amount of dissolved oxygen consumed by the diluted sample (D ₁ -D ₂ ) is 5.0 mg/L. A is the median value of the amount of dissolved oxygen consumed by this diluted sample (D ₁ -D ₂ ), 5.0 mg/L.

As described above, the method for determining the amount of BOD sample to be collected of the second embodiment of the present invention utilizes the correlation between the absorbance of a sample measured using a UV absorptiometer with light of a wavelength of 254 nm and the BOD (mg/L) of the sample obtained by analysis using an official method, and from this obtains a predicted BOD value E _BOD (mg/L) for the sample to determine the amount of sample to be collected, and shares a common technical concept with the method for determining the amount of COD sample to be collected of the first embodiment of the present invention.

Figure 3 is a configuration diagram of an automatic COD measurement device 1 according to a third embodiment of the present invention, where Figure 3(A) is an overall configuration diagram and Figure 3(B) is a functional configuration diagram of a control device 70. The automatic COD measurement device 1 includes a sample collection device 10 that automatically collects an appropriate amount of an official method sample and sends it to a COD analysis device 50, and a COD analysis device 50 that measures the COD of the sample.

The sample collection device 10 is equipped with a sample collection line 12 that sends samples to the COD analysis device 50. The sample collection line 12 is equipped with an autosampler 14 that collects samples, a liquid delivery pump 16 that delivers the sample, a UV absorptiometer 18 with an inserted flow cell that measures the absorbance of the sample, and a dispensing burette 20 that dispenses a determined amount of sample. The sample collection device 10 is connected to a control device 70 so that data can be sent and received, and the control device 70 controls the operation.

The COD analyzer 50 is a COD analyzer having a configuration that complies with the official method, and includes a reagent tank 53 for storing reagents, a reagent supplying means 52 that automatically collects a fixed amount of the stored reagent and supplies it to a reaction tank 56, a reaction means 55 that includes the reaction tank 56 and a heater 57 consisting of a water bath or oil bath that heats the reaction tank 56, a titration means 60 that includes a titrator 62 and a detector 63 that detects the end point, and a control means 70 that processes data and controls the operation of each device and instrument. In addition to the above means, the COD analyzer 50 also includes a cleaning means for cleaning the reaction tank 56, etc., a waste liquid tank for storing waste liquid, etc.

The control device 70 includes a data transmission/reception means 71 for connecting to each device/equipment so that data can be transmitted and received, an input means 72 consisting of a touch panel for inputting data, a CD reader, etc., an output means 73 such as a display or printer for outputting data, a storage means 74 for storing various data/programs, etc., a control means 75 for controlling each means, and a data processing means 76 for processing data.

In the storage means 74, a program for collecting an appropriate amount of sample specified by the official method, a program for operating each device and means of the COD analysis device 50 according to the analysis procedure specified by the official method, and a data processing program for calculating COD, etc. are installed. The program for collecting an appropriate amount of sample specified by the official method is a program of the method for determining the COD sample collection amount of the first embodiment of the present invention, and includes a correlation equation between the absorbance of the sample and COD, and equations (1) and (2).

The control device 70 configured as described above is realized by a computer on which the program is installed, a programmable logic controller, and peripheral devices such as a display.

The operation of the automatic COD measurement device 1 of the third embodiment will be described. The control device 70 operates the sample collection device 10 and controls it to collect an appropriate amount of sample for the official method. Specifically, the control device 70 issues a command to the UV absorptiometer 18 to measure the absorbance of the sample with light of a wavelength of 254 nm during the process of sending the sample from the autosampler 14 to the COD analysis device 50 and co-washing the sample collection line 12, which is performed prior to sample collection. Upon receiving this command, the UV absorptiometer 18 measures the absorbance of the sample and sends the measurement value to the control device 70.

The control device 70 uses the absorbance data from the UV spectrophotometer 18 and a program for collecting an appropriate amount of official method sample stored in the memory means 74 to determine the appropriate amount of sample and controls the fractionation burette 20 to fractionate that amount. The fractionation burette 20 collects the appropriate amount of sample and sends it to the COD analysis device 50.

Next, the control device 70 reads out a program stored in the memory means 74 for operating each device and means of the COD analysis device 50 according to the analysis procedure prescribed in the official method, and operates each device and means of the COD analysis device 50 according to the analysis procedure prescribed in the official method. The operation of the COD analysis device 50 is outlined below.

The control device 70 controls the reaction means 55 and the reagent supply means 52 to add an appropriate amount of water to the sample delivered from the sample collection device 10, add a specified amount of sulfuric acid, and add a specified silver nitrate solution while stirring, thereby masking the chloride ions in the sample. Next, the control device 70 controls the reaction means 55 and the reagent supply means 52 to add a specified amount of potassium permanganate solution, stir, and immediately heat the reaction tank 56 with the heater 57 for 30 minutes.

Then, the control device 70 removes the reaction tank 56 from the heater 57, adds the specified sodium oxalate, stirs and controls the reaction means 55 and the reagent supply means 52 so that the reaction takes place, and then controls the titration means 60 so that the solution is titrated with the specified potassium permanganate solution at a liquid temperature of 50 to 60°C. Separately, the same operation is performed for water. The obtained results are processed by the data processing means 76, and the measurement results are output to the output means 73.

In the third embodiment of the automatic COD measurement device 1 configured as described above, the sample collection device 10 automatically collects an appropriate amount of sample for the official method based on the absorbance measured by the UV absorptiometer 18, and the COD analysis device 50 performs analysis according to the official method, so that the appropriate amount of sample can be collected for COD analysis and the validity of the analysis results can be confirmed.

Next, a first modified example of the COD automatic measurement device 1 of the third embodiment will be described. In the first modified example, the control device 70 includes a COD database 81 that records data (hereinafter, COD data) linking absorbance and COD in the storage means 74, and a data correction means 82 in the data processing means 76. The data correction means 82 is for correcting the correlation equation between the absorbance and COD of a sample in a program for collecting an appropriate amount of an official method sample that has been input in advance. The control device 70 operates as follows.

When the COD measurement of the sample by the COD analyzer 50 is completed, the control device 70 links the absorbance measured by the UV absorptiometer 18 with the COD measured by the COD analyzer 50, and records this as COD data in the COD database 81. The control device 70 also periodically operates the data correction means 82, reads out the COD data from the COD database 81, imports the data, and corrects the correlation equation between the absorbance and COD of the sample. After the correlation equation between absorbance and COD has been corrected, the data processing means 76 determines the appropriate amount of sample for the official method based on the corrected correlation equation.

Next, a second modified example of the COD automatic measurement device 1 of the third embodiment is shown. In the second modified example, as in the first modified example, the storage means 74 of the control device 70 is provided with a COD database 81, and the data processing means 76 is provided with a data correction means 82.

Prior to sampling and measuring COD, the control device 70 displays on the output means 73 a request to input the name of the sample to be analyzed, and after the sample name is input via the input means 72, it operates the sample sampling device 10 and the COD analysis device 50. When the control device 70 has completed measuring the COD of the sample, it links the sample name, the absorbance measured by the UV absorptiometer 18, and the COD measured by the COD analysis device 50, and records this as COD data in the COD database 81.

The control device 70 also periodically operates the data correction means 82, reads out COD data from the COD database 81, imports the corresponding data for each sample, and creates or corrects the correlation equation between absorbance and COD for each sample. After the correlation equation between absorbance and COD has been corrected, the data processing means 76 determines the appropriate amount of sample for the official method based on the correlation equation corresponding to the sample.

The first variant of the automatic COD measuring device 1 of the third embodiment accumulates COD data and uses the data to review the correlation equation between the absorbance and COD of the sample, while the second variant of the automatic COD measuring device 1 of the third embodiment accumulates COD data for each sample and uses the data to review or create the correlation equation between the absorbance and COD for each sample, thereby enabling accurate collection of an appropriate amount of sample and confirming the validity of the analysis results.

The automatic COD measurement device according to the present invention has been described above using the automatic COD measurement device 1 of the third embodiment, the first modification, and the second modification, but the automatic COD measurement device according to the present invention is not limited to the above-mentioned embodiment. The COD analysis device 50 of the automatic COD measurement device according to the present invention may have a different configuration as long as it is capable of implementing the official method.

In the third embodiment of the COD automatic measurement device 1, the control device 70 is incorporated in the COD analysis device 50, but the control device 70 may be separated from the COD analysis device 50 and made independent, or a part of the control device 70 may be separated from the COD analysis device 50 and made independent. Also, a separate control device for sample collection may be provided in the sample collection device 10, and the control device 70 may be mainly responsible for the COD analysis device 50.

The sample collection device 10 (including the control means) constituting the automatic COD measurement device 1 of the third embodiment can be said to be composed of a means for determining the appropriate amount of sample for the official method, and a means for automatically collecting the determined sample and sending it to the COD analysis device 50. Therefore, the former means for determining the appropriate amount of sample for the official method (including the control means) can also be an independent sample collection amount determination device. By incorporating such a device into an existing COD analysis device, the automatic COD measurement device of the present invention can be obtained.

Figure 4 is a block diagram of an automatic dilution device 100 according to a fourth embodiment of the present invention, where Figure 4(A) is an overall block diagram and Figure 4(B) is a functional block diagram of a control device 165. The automatic dilution device 100 is a device for preparing a diluted sample for BOD measurement, and is equipped with a UV absorptiometer 118 for measuring the absorbance of the sample, an automatic sample collection means 111 for collecting an appropriate amount of a sample for an official method, a sample preparation means 130 for adding dilution water to the sample to prepare a specified diluted sample, and a control device 165 for connecting to each device and apparatus and controlling their operation. The dilution water is specified by the official method. Note that when sample pretreatment is required or when inoculation dilution water is used, each means according to the official method is prepared and operations according to the official method are performed.

The control device 165 includes a data transmission/reception means 171 for connecting to each device/equipment so that data can be transmitted and received, an input means 172 consisting of a touch panel for inputting data, a CD reader, etc., an output means 173 such as a display or printer for outputting data, a storage means 174 for storing various data/programs, etc., a control means 175 for controlling each means, and a data processing means 176 for processing data.

The storage means 174 is installed with a program for collecting an appropriate amount of sample specified by the official method, and a program for preparing diluted samples with stepwise different dilution ratios. The program for collecting an appropriate amount of sample specified by the official method is a program version of the BOD sample collection amount determination method of the second embodiment of the present invention, and includes a correlation equation between the absorbance of the sample and the BOD, as well as equations (3) and (4).

The control device 165 having the above configuration is realized by a computer on which the program is installed, a programmable logic controller, and peripheral devices such as a display.

Upon receiving a command from the control device 165, the UV absorptiometer 118 measures the absorbance of the sample using light with a wavelength of 254 nm and sends the measured value to the control device 165. The control device 165 uses the absorbance data from the UV absorptiometer 118 and a program stored in the memory means 174 for collecting the appropriate amount of sample for the official method to determine the appropriate amount of sample.

The automatic sample collection means 111 receives a command from the control device 165 and collects an appropriate amount of sample. The diluted sample preparation means 130 adds dilution water to the collected sample and stirs it to prepare a diluted sample, and further adds dilution water to a portion of the diluted sample and stirs it to prepare diluted samples with different dilution ratios in stages.

In the fourth embodiment of the automatic dilution device 100 configured as described above, the automatic sample collection means 111 automatically collects an appropriate amount of official method sample based on the absorbance measured by the UV absorptiometer 118, and the diluted sample preparation means 130 prepares diluted samples with different dilution ratios in stages, thereby achieving the collection of an appropriate amount of sample for BOD analysis and confirming the validity of the analysis results.

The automatic dilution device 100 of the fourth embodiment can be said to be composed of a means for determining the appropriate amount of sample for the official method, a means for automatically collecting the determined sample, and a means for diluting the sample and preparing a diluted sample. Therefore, the former means for determining the appropriate amount of sample for the official method (including the control means) can be made into an independent sample collection amount determination device. By incorporating such a device into an existing automatic dilution device, the automatic dilution device of the present invention can be obtained.

Figure 5 is a block diagram of the BOD automatic measurement device 2 of the fifth embodiment of the present invention, where Figure 5(A) is an overall block diagram and Figure 5(B) is a functional block diagram of the control device 170. The same components as those of the automatic dilution device 100 of the fourth embodiment of the present invention shown in Figure 4 are given the same reference numerals and will not be described. The BOD automatic measurement device 2 is a device that automatically collects an appropriate amount of sample for the official method, adds dilution water to the sample to prepare a diluted sample, and analyzes the BOD according to the official method, and is equipped with the automatic dilution device 100, a BOD analysis device 150, and a control device 170.

The automatic dilution device 100 of the BOD automatic measurement device 2 of the fifth embodiment has the same basic configuration as the automatic dilution device 100 of the fourth embodiment of the present invention. In the BOD automatic measurement device 2 of the fifth embodiment, the automatic dilution device 100 is controlled by the control device 170. When sample pretreatment is required or when inoculation dilution water is used, each means is prepared according to the official method and operations are performed according to the official method, just like the automatic dilution device 100.

The BOD analyzer 150 is a BOD analyzer having a configuration that complies with the official method, and includes an incubator 157 that maintains the sealed flank bottle filled with the diluted sample at a predetermined temperature, a storage stocker that stores the flank bottles, a means for extracting and transporting the flank bottles, an incubation means 155 that includes a stopper opening and closing means for opening and closing the stopper of the flank bottle, and a DO measurement means 160 that measures the dissolved oxygen in the diluted sample.

The control device 170 includes a data transmission/reception means 171 for connecting to each device/equipment so that data can be transmitted and received, an input means 172 consisting of a touch panel for inputting data, a CD reader, etc., an output means 173 such as a display or printer for outputting data, a storage means 174 for storing various data/programs, etc., a control means 175 for controlling each means, and a data processing means 176 for processing data.

In the storage means 174, a program for collecting an appropriate amount of sample specified by the official method, a program for operating each device and means of the BOD analysis device 150 according to the analysis procedure specified by the official method, and a data processing program for calculating BOD, etc. are installed. The program for collecting an appropriate amount of sample specified by the official method is a program of the BOD sample collection amount determination method of the second embodiment of the present invention, and includes a correlation equation between the absorbance of the sample and the BOD, as well as equations (3) and (4).

The control device 170 configured as described above is realized by a computer on which the program is installed, a programmable logic controller, and peripheral devices such as a display.

The operation of the BOD automatic measurement device 2 of the fifth embodiment will be described. The control device 170 operates the automatic dilution device 100 to collect an appropriate amount of the official method sample, and then controls it to prepare a diluted sample.

Specifically, the UV absorptiometer 118 receives a command from the control device 170, measures the absorbance of the sample with light of 254 nm wavelength, and sends the measured value to the control device 170. The control device 170 uses the absorbance data from the UV absorptiometer 118 and a program for collecting an appropriate amount of sample for the official method stored in the memory means 174 to determine the appropriate amount of sample, and issues a command to the automatic sample collection means 111 to collect the appropriate amount of sample. The control device 170 then adds dilution water to the collected sample, stirs it to prepare a diluted sample, and controls the diluted sample preparation means 130 to fill the flan bottle.

Next, the control device 170 reads out a program stored in the memory means 174 for operating each device and means of the BOD analysis device 150 according to the analysis procedure prescribed in the official method, and operates each device and means of the BOD analysis device 150 according to the analysis procedure prescribed in the official method. The operation of the BOD analysis device 150 is outlined below.

The control device 170 controls the DO measurement means 160 to measure the dissolved oxygen 15 minutes after preparation of the diluted sample, and records the measured value in the memory means 174. The sealed Franc bottle filled with the diluted sample is stored in a storage stocker and incubated in an incubator 157 for 5 days under specified conditions, after which the dissolved oxygen in the diluted sample is measured and recorded in the memory means 174. The obtained results are processed by the data processing means 176, and the measurement results are output to the output means 173.

In the fifth embodiment of the BOD automatic measurement device 2 configured as described above, the automatic dilution device 100 automatically collects an appropriate amount of sample for the official method based on the absorbance measured by the UV absorptiometer 118, dilutes the sample with dilution water to prepare diluted samples with different dilution ratios in stages, and the BOD analysis device 150 analyzes the sample according to the official method. This allows for the collection of an appropriate amount of sample for BOD analysis and also confirms the validity of the analysis results.

Next, a first modified example of the BOD automatic measurement device 2 of the fifth embodiment will be described. In the first modified example, the control device 170 includes a BOD database 181 that records data (hereinafter, BOD data) linking absorbance and BOD in the storage means 174, and a data correction means 182 in the data processing means 176. The data correction means 182 is for correcting the correlation equation between the absorbance and BOD of a sample in a program for collecting an appropriate amount of an official method sample that has been input in advance. The control device 170 operates as follows.

When the measurement of the BOD of the sample by the BOD analyzer 150 is completed, the control device 170 links the absorbance measured by the UV absorptiometer 118 with the BOD measured by the BOD analyzer 150, and records this as BOD data in the BOD database 181. The control device 170 also periodically operates the data correction means 182, reads out the BOD data from the BOD database 181, imports the data, and corrects the correlation equation between the absorbance and BOD of the sample. After the correlation equation between absorbance and BOD has been corrected, the data processing means 176 determines the appropriate amount of sample for the official method based on the corrected correlation equation.

Next, a second modified example of the BOD automatic measurement device 2 of the fifth embodiment is shown. In the second modified example, as in the first modified example, the storage means 174 of the control device 170 is provided with a BOD database 181, and the data processing means 176 is provided with a data correction means 182.

Prior to collecting a sample and measuring the BOD, the control device 170 displays on the output means 173 a request to input the name of the sample to be analyzed, and after the sample name is input via the input means 172, it operates the automatic dilution device 100 and the BOD analyzer 150. When the control device 170 has completed measuring the BOD of the sample, it links the sample name, the absorbance measured by the UV absorptiometer 118, and the BOD measured by the BOD analyzer 150, and records this as BOD data in the BOD database 181.

The control device 170 also periodically operates the data correction means 182, reads out the BOD data from the BOD database 181, imports the corresponding data for each sample, and creates or corrects the correlation equation between the absorbance and BOD for each sample. After the correlation equation between the absorbance and BOD has been corrected, the data processing means 176 determines the appropriate amount of sample for the official method based on the correlation equation corresponding to the sample.

The first variant of the BOD automatic measurement device 2 of the fifth embodiment accumulates BOD data and uses the data to review the correlation equation between the absorbance and BOD of the sample, while the second variant of the BOD automatic measurement device 2 of the fifth embodiment accumulates BOD data for each sample and uses the data to review or create the correlation equation between the absorbance and BOD of each sample, thereby enabling accurate collection of an appropriate amount of sample and confirming the validity of the analysis results.

The above describes the automatic BOD measurement device of the present invention using the automatic BOD measurement device 2 of the fifth embodiment, the first modification, and the second modification, but the automatic BOD measurement device of the present invention is not limited to the above embodiment. The BOD analysis device 150 of the automatic BOD measurement device of the present invention may have a different configuration as long as it is capable of implementing the official method. Furthermore, the configuration of the control device 170 is not limited to the above embodiment.

As described above, a preferred embodiment has been described with reference to the drawings. However, a person skilled in the art would easily imagine various changes and modifications within the obvious scope upon reading this specification. Therefore, such changes and modifications are to be interpreted as being within the scope of the invention as defined by the claims.

1 Automatic COD measurement device 2 Automatic BOD measurement device 10 Sample collection device 12 Sample collection line 18 UV absorptiometer 50 COD analysis device 70 Control device 81 COD database 82 Data correction means 100 Automatic dilution device 111 Automatic sample collection means 118 UV absorptiometer 130 Diluted sample preparation means 150 BOD analysis device 155 Cultivation means 157 Incubator 160 DO measurement means 165 Control device 170 Control device 181 BOD database 182 Data correction means

Claims (6)

Measuring the absorbance of the sample using a UV spectrophotometer during the co-washing of the sample collection line with the sample;
A step of determining a sample collection volume V (mL) from a predicted BOD value E _BOD (mg/L) of the sample calculated using the correlation between the absorbance and BOD of the sample and from equations (3) and (4);
A method for determining a BOD sample collection amount, comprising:
V = A × v / E _BOD ... (3)
A = 5.0 ... (4)
Here, A is the median (mg/L) of the dissolved oxygen consumption (D ₁ -D ₂ ) of the diluted sample.
v is the volume of the diluted sample (mL) a UV spectrophotometer having a flow cell attached to a sample collection line for measuring the absorbance of the sample;
a sample collection amount determination means for determining an appropriate sample collection amount V (mL) of the sample, as defined by the official method, from a predicted BOD value E _BOD (mg/L) of the sample calculated using the correlation between the absorbance and BOD of the sample and a relational expression between the predicted BOD value E _BOD (mg/L) and an appropriate amount of the sample, as defined by the official method;
an automatic sample collection means for automatically collecting the sample amount V (mL) determined by the sample collection amount determination means;
A diluted sample preparation means for adding dilution water to the collected sample to prepare diluted samples with different dilution ratios and filling the diluted samples into the flask;
A control device for controlling the operation of the device and each of the means;
Equipped with
The automatic dilution apparatus is characterized in that the control device controls the UV absorptiometer to measure absorbance during the process in which the sample is delivered and the sample collection line is co-washed. 3. The automatic dilution device according to claim 2, wherein the relationship between the BOD predicted value E _BOD (mg/L) defined by the official method and the appropriate amount of sample is expressed by the following formulas (3) and (4).
V = A × v / E _BOD ... (3)
A = 5.0 ... (4)
Here, A is the median (mg/L) of the dissolved oxygen consumption (D ₁ -D ₂ ) of the diluted sample.
V is the sample volume (mL)
v is the volume of the diluted sample (mL) The automatic dilution device according to claim 2 or 3,
a BOD analyzer including a dissolved oxygen measuring means for measuring the dissolved oxygen in the diluted sample and a thermostatic chamber for storing the flask;
A control device for controlling the operation of the BOD analysis device;
A BOD automatic measuring device comprising: a data storage means for storing BOD data in which the absorbance of the sample measured by the UV absorptiometer and the BOD of the sample measured by the BOD analyzer are linked;
A correction means for correcting a correlation between absorbance and BOD of a sample, which has been previously obtained, using the BOD data;
Equipped with
5. The BOD automatic measuring device according to claim 4, wherein said sample collection amount determining means determines said sample collection amount V by using a correlation between the corrected absorbance of the sample and the BOD. Measuring the absorbance of the sample using a UV spectrophotometer during the co-washing of the sample collection line with the sample;
determining a sample collection volume V (mL) from a predicted COD value E _COD (mg/L) of the sample calculated using the correlation between the absorbance and COD of the sample and from equations (1) and (2);
A method for determining a COD sample collection amount, comprising:
V = 0.2 × (a - b) × f × 1000 / E _COD ... (1)
a-b=4.5... (2)
However, when V≧100, V=100
Here, a-b is the median of the titration value (titration amount - blank test value) (mL).
f is the factor of 5 mmol/L potassium permanganate solution

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