JP2005140757A - Approximation bod5 measurement method, approximation bod5 measuring device, water quality monitoring apparatus using the device, and wastewater treatment system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an approximation BOD5 measuring apparatus and an approximation BOD<SB>5</SB>measurement method capable of quickly, precisely measuring the approximate BOD<SB>5</SB>concentration. <P>SOLUTION: The aging data of biosensor output (S) in BODs concentration measurement by a BODs measuring apparatus 10 are acquired for standard and sample solutions; organic carbon concentration (TOCin, TOCout), before and after the BODs concentration measurement for the standard and sample solutions, is measured by a TOC meter 13; index data (D) regarding BOD<SB>5</SB>are extracted form the biosensor output (S) for the standard and sample solutions; a TOC decomposition rate is calculated, based on the organic carbon concentration (TOCin, TOCout), before and after the BODs measurement; converted index data (E) which are converted to the index data, when entire organic carbon contents contained in the standard and sample solutions are decomposed are calculated, based on the TOC decomposition rate and the index data (D) for the standard and sample solutions; and BOD<SB>5</SB>concentration (F) is calculated, on the basis of the converted index data of the standard and sample solutions. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a method and apparatus for measuring BOD ₅ (biochemical oxygen demand) concentration used as an indicator of organic contamination in wastewater treatment of domestic wastewater, factory wastewater, etc., and water quality monitoring of rivers, etc. The present invention relates to an approximate BOD ₅ measurement method and an approximate BOD ₅ measurement apparatus that can accurately measure BOD ₅ in a short time.
The present invention also relates to a water quality monitoring device and a waste water treatment system that perform water quality monitoring and waste water treatment by applying the approximate BOD ₅ measuring device.

Usually, the quality of wastewater discharged into rivers is regulated by BOD (Biochemical Oxygen Demand), which is one of the management indices using microorganisms.
BOD is the amount of dissolved oxygen consumed when an organic substance is decomposed by aerobic microorganisms in water. According to the official method stipulated in JIS K0102, dissolved oxygen consumed for 5 days at 20 ° C. The amount is expressed in ppm or O ₂ mg / L.
BOD includes BOD (BODs described later) measured by a simple measurement method other than the method defined in JIS K0102, and is obtained by an official method defined in JIS K0102 to distinguish between the two. The BOD is hereinafter referred to as BOD ₅ .

The BOD ₅ measurement method takes 5 days to obtain measurement results. However, since wastewater treatment facilities require real-time information about the quality of the wastewater currently flowing through the wastewater treatment facility, the water quality of the water can be measured by using the BOD ₅ measurement method, which takes 5 days until the measurement results are obtained. It cannot be managed.

Therefore, TOC (organic carbon content) meter and TOD (total oxygen consumption) meter with short measurement time are used to quantify organic carbon concentration in wastewater, and BOD ₅ concentration and TOC concentration (or TOD concentration) accumulated in the past. A management method for statistically predicting the BOD ₅ concentration from the BOD ₅ concentration / TOC concentration ratio and the BOD ₅ concentration / TOD concentration ratio is frequently used.

On the other hand, BOD concentration (hereinafter referred to as BOD concentration by biosensor is referred to as BODs concentration in order to distinguish it from BOD ₅ concentration) in a short time using a biosensor (referred to as a membrane composed of a microorganism-fixed membrane and an oxygen electrode). A BODs measuring apparatus that simply measures the above is widely used (see Patent Document 1).
Japanese Patent Publication No.61-7258

  JIS K 3602 defines a method for measuring the BODs concentration with a BODs measuring device (for example, using BF-2000 manufactured by Oji Scientific Instruments). FIG. 3 is a diagram for explaining a measurement cycle when measuring the BODs concentration by this BODs measuring device, and FIG. 4 is a diagram for explaining a measurement principle of the BODs concentration (a diagram for explaining calculating BODs from biosensor output). ).

A standard solution (glucose / glutamic acid solution, BOD ₅ concentration is 20 [mg / L]) and a sample solution containing an organic substance and the like are sequentially supplied to a flow cell equipped with a biosensor. When these solutions come into contact with the microbial membrane at the tip of the biosensor, glucose / glutamic acid in the standard solution, organic substances in the sample, and the like are decomposed.

This microbial degradation consumes dissolved oxygen in the standard solution and the sample solution. At this time, consumption of dissolved oxygen can be detected as the output of the oxygen electrode. The BODs concentration can be obtained by the following equation (1) by detecting the output change amount for the sample solution and the standard solution having a known BOD ₅ concentration (for example, 20 [mg / L]).

    BODs concentration = (maximum output change Y of sample solution / maximum output change X of standard solution) × 20 [mg / L] (1)

The sample solution maximum output change amount (Y) and the standard solution maximum output change amount (X) to be substituted into the equation (1) are sequentially measured at the timing shown in FIG.
That is, first, the sample solution is supplied for 3 minutes, and then the washing water is supplied for 15 minutes to wash the flow cell and the like, and waits for the output signal S to return to the baseline.

  Subsequently, a standard solution (indicated by STD in the figure) is supplied to the flow cell for 5 minutes, and the output of the biosensor is plotted. Then, the maximum difference of the biosensor output S for 5 minutes is acquired as the “standard solution output value” (maximum output change amount X of the standard solution). Continue to flush for 15 minutes and wait for it to return to baseline.

  Subsequently, a sample solution (indicated by SPL in the figure) is supplied to the flow cell for 5 minutes, and the output of the biosensor is plotted. Then, the maximum difference in biosensor output S for 5 minutes is acquired as “sample solution output value” (maximum output change amount Y of sample solution). Continue to flush for 15 minutes and wait for it to return to baseline.

  Then, the BODs concentration is calculated from the obtained “standard solution output value” (maximum output change amount X of standard solution), “sample solution output value” (maximum output change amount Y of sample solution), and equation (1).

According to the BODs measurement method according to JIS K3602 using the BODs measurement device described above, the concentration of BODs can be measured in about 1 hour, but the properties of waste water to be measured, particularly the organic compounds contained (biosensors) The BODs concentration and the BOD ₅ concentration did not necessarily coincide with each other because the degree of difficulty in biodegradation varies depending on the substance that inhibits the activity of the microorganism used in the above.

For example, even if the maximum change amount of the oxygen electrode output value is the same for the standard solution and the sample solution that are the basis for calculating the BODs concentration, the curve shape of the change over time of the biosensor output output to the external printer depends on the properties of the sample. The BOD ₅ concentration of samples with different time courses could not be predicted from the BODs concentration.

Therefore, even if the BODS measuring device even when measured BODS concentration, BODS concentrations treated as different from the BOD ₅ concentrations, as in the case of TOC meter or TOD meter, a BOD ₅ concentration of BOD ₅ concentration / BODS concentration ratio It had to be predicted statistically.

As described above, the method of statistically predicting the BOD ₅ concentration from the BOD ₅ concentration / TOC concentration ratio, the BOD ₅ concentration / TOD concentration ratio, and the BOD ₅ concentration / BODs concentration ratio with reference to past accumulated data is Although it is indispensable in the measurement that requires real-time wastewater treatment and water quality management, it has the following disadvantages.

The past data of the BOD ₅ concentration, the TOD concentration, the TOC concentration, and the BODs concentration of the wastewater to be measured had to be accumulated so that it could be used as a database.
Further, even if each of the above data is accumulated, it is necessary to always replace the old measurement data with the latest measurement data for updating.
In addition, in factories and the like, past accumulated data is not necessarily reproduced due to changes in business activities, troubles, and the like, and there are cases where the situation judgment and response are not appropriate.
Therefore, a method that can measure approximate BOD ₅ concentration (an alternative BOD concentration approximated to the original BOD ₅ concentration value measured over 5 days), not statistical prediction based on accumulated data from the past, is eagerly desired. It had been.

Accordingly, an object of the present invention is to provide a new approximate BOD ₅ measurement method and approximate BOD ₅ measurement apparatus that can measure the BOD ₅ concentration accurately and quickly.
It is another object of the present invention to provide a new approximate BOD ₅ measurement method, a water quality monitoring device using the approximate BOD ₅ measurement device, and a wastewater treatment system.

The approximate BOD ₅ measurement method of the present invention, which has been made to solve the above-mentioned problems, is performed when measuring BODs concentration with a BODs measurement device using a biosensor for each of a standard solution with a known BOD ₅ concentration and a sample solution to be measured. Change data of biosensor output (S) over time, obtain data related to changes in organic carbon concentration before and after measuring BODs concentration by BODs measuring device for each of standard solution and sample solution, and obtain standard solution and sample solution Index data related to BOD ₅ concentration is extracted from the biosensor output (S) change data for each, and the standard is based on the index data and data related to the change in organic carbon concentration for each of the standard solution and the sample solution. Conversion converted into index data when all organic carbon contained in the liquid or sample liquid is decomposed Calculating a target data, and to calculate the BOD ₅ concentration based on each conversion index data of the standard solution and the sample solution.

The approximate BOD ₅ measurement method of the present invention, instead of statistically predict BOD ₅ concentration using the original BODs concentration obtained from BODs measuring device, BOD from the output of the biosensor BODs measuring device (S) ₅ The BOD ₅ concentration is measured by a completely new method of directly extracting the index data serving as an index of the measurement and calculating the BOD ₅ concentration based on the extracted index data.

That is, index data is directly extracted from the output (S) of the biosensor of the BODs measuring apparatus, and further, it is related to changes in the organic carbon concentration in the standard solution and the sample solution before and after the BODs concentration measurement. Get the data.
Further, based on the extracted index data and the data related to the change in the organic carbon concentration, the conversion index data converted into the index data when all the organic carbon contained in the standard solution and the sample liquid is decomposed is calculated. As a result, standardized data is obtained that eliminates the effects of variations in the degree of decomposition of organic carbon contained in the standard solution and sample solution.
Then, the BOD ₅ concentration is calculated based on the conversion index data of the standard solution and the conversion index data of the sample solution.

The BOD ₅ concentration calculated by this method is in good agreement with the BOD ₅ concentration actually measured based on the official method of JIS K0102, and as will be described later, the BOD ₅ concentration is rapidly obtained (measurement results are obtained in about 1 hour). It has been experimentally confirmed that it can be an accurate measurement method.

Further, the approximate BOD ₅ measurement method of the present invention is the biosensor output (S) when measuring the BODs concentration by the BODs measurement device using the biosensor for each of the standard solution with known BOD ₅ concentration and the sample solution to be measured. The time-dependent change data is obtained, and the data related to the organic carbon concentration before and after the BODs concentration measurement by the BODs measuring device is measured for each of the standard solution and the sample solution, and the biosensor output (S The index data related to the BOD ₅ concentration is extracted from the time-dependent data of), and the TOC decomposition rate is calculated based on the data related to the organic carbon concentration before and after the BODs concentration measurement for each of the standard solution and the sample solution. Standard solution and sample solution based on TOC decomposition rate and index data Calculating a conversion index data in terms of the index data when Murrell organic carbon is decomposed all may be calculated BOD ₅ concentration based on each conversion index data of the standard solution and the sample solution.
According to this, the TOC decomposition rate can be used as data relating to the change in the organic carbon concentration, and accurate measurement can be performed by using the TOC decomposition rate.

Further, the approximate BOD ₅ measurement method of the present invention is the biosensor output (S) when measuring the BODs concentration by the BODs measurement device using the biosensor for each of the standard solution with known BOD ₅ concentration and the sample solution to be measured. After obtaining the time course data of the sample, the organic carbon concentration (TOCin) before measuring the BODs concentration with the BODs measuring device was measured with the TOC meter for each of the standard solution and the sample solution, and the BODs concentration was measured with the BODs measuring device. The organic carbon concentration (TOCout) for each of the standard solution and the sample solution is measured with a TOC meter, and the index data related to the BOD ₅ concentration is obtained from the time-dependent data of the biosensor output (S) for each of the standard solution and the sample solution. Extraction of the standard solution and the sample solution before and after measuring the BODs concentration Calculate the TOC decomposition rate based on the body carbon concentration (TOCin, TOCout), and all the organic carbon contained in the standard solution and the sample solution based on the TOC decomposition rate and the index data for each of the standard solution and the sample solution Conversion index data converted into index data in the case of decomposition may be calculated, and the BOD ₅ concentration may be calculated based on the respective conversion index data of the standard solution and the sample solution.
According to this, the organic carbon body density | concentration obtained by the organic carbon body density | concentration measurement by a TOC meter can be utilized.

In the approximate BOD ₅ measurement method of the present invention, the data related to the organic carbon concentration before and after the BODs concentration measurement may be measured by any one of a TOC meter, a TOD meter, a COD meter, and an absorbance detector. .
According to this, the data corresponding to the change in the organic carbon concentration can be acquired using any one of the TOC meter, the TOD meter, the COD meter, and the absorbance detector.

The approximate BOD ₅ measurement method of the present invention uses, as the index data, the integrated value of the biosensor output in the region where the biosensor output (S) immediately after the start of measurement for each of the standard solution and the sample solution changes linearly with time. You may do it.
The BOD ₅ concentration calculated by this method is in good agreement with the BOD ₅ concentration actually measured based on the official method of JIS K0102, and a value very close to the actually measured BOD ₅ concentration is irrespective of the properties of the sample. It was confirmed experimentally that it was obtained.
As will be described later, it has been experimentally confirmed that it can be a rapid and accurate measurement method of BOD ₅ concentration (a measurement result can be obtained in about 1 hour).

Further, in the approximate BOD ₅ measurement method of the present invention, the BODs concentration measurement by the BODs measurement device may alternately perform the BODs concentration measurement for the standard solution and the BODs concentration measurement for the sample solution.
The output of the biosensor has a tendency that the influence of the previous measurement remains historically in the next measurement. Therefore, instead of measuring the sample solution continuously, instead of measuring the sample solution and the standard solution alternately, the measurement of the standard solution is always performed immediately before the measurement of each sample solution. The historical influence can be equalized.

Further, an approximate BOD ₅ measuring device of the present invention made to solve the above problems includes a fluid supply unit that supplies a plurality of fluids including at least a standard solution having a known BOD ₅ concentration and a sample solution to be measured, A BODs measuring device for measuring the BODs concentration of each of the standard solution and the sample solution using a sensor, a collection unit for collecting the standard solution and the sample solution after the BODs concentration is measured by the BODs measuring device, and a standard solution For each of the standard solution and the sample solution, the detector for measuring the data related to the organic carbon concentration before the BODs concentration measurement by the BODs measuring device of each of the sample solution and the data related to the organic carbon concentration after the BODs concentration measurement, and the standard solution and the sample solution index data for extracting index data relating to the BOD ₅ concentrations from aging data biosensor output (S) of the BODs measuring device Index data when all organic carbon contained in the standard solution and sample solution is decomposed based on the data related to the organic carbon before and after the BODs concentration measurement and the index data for each of the extraction unit, the standard solution, and the sample solution so that provided the terms of the index data calculation unit for calculating a conversion index data obtained by converting, a BOD ₅ calculation unit for calculating a BOD ₅ concentration based on each conversion metrics of standards and the sample solution to.
According to this, the epoch-making BOD ₅ measuring apparatus which can measure a BOD ₅ density | concentration rapidly and accurately using the BOD ₅ measuring method mentioned above can be provided.

Further, an approximate BOD ₅ measuring device of the present invention made to solve the above problems includes a fluid supply unit that supplies a plurality of fluids including at least a standard solution having a known BOD ₅ concentration and a sample solution to be measured, A BODs measuring device for measuring the BODs concentration of each of the standard solution and the sample solution using a sensor, a collection unit for collecting the standard solution and the sample solution after the BODs concentration is measured by the BODs measuring device, and a standard solution For each of the standard solution and the sample solution, the detector for measuring the data related to the organic carbon concentration before the BODs concentration measurement by the BODs measuring device of each of the sample solution and the data related to the organic carbon concentration after the BODs concentration measurement, and the standard solution and the sample solution index data for extracting index data relating to the BOD ₅ concentrations from aging data biosensor output (S) of the BODs measuring device Extraction unit, change rate calculation unit for calculating TOC decomposition rate based on data related to organic carbon before and after BODs concentration measurement for each of standard solution and sample solution, and TOC decomposition rate for each of standard solution and sample solution Conversion index data calculation unit for calculating conversion index data converted into index data when all the organic carbon contained in the standard solution and the sample solution is decomposed based on the index data and the index data, and each of the standard solution and the sample solution based on the conversion index data may be provided with a BOD ₅ calculation unit for calculating a BOD ₅ concentrations.

Further, the approximate BOD ₅ measuring device of the present invention includes at least a standard solution having a known BOD ₅ concentration, a fluid supply unit that supplies a plurality of fluids including a sample solution to be measured, and a standard solution and sample using a biosensor. A BODs measuring device that measures the BODs concentration of each liquid, a collection unit that collects the standard solution and the sample solution after the BODs concentration is measured by the BODs measuring device, and a BODs measuring device for each of the standard solution and the sample solution The TOC meter for measuring the organic carbon concentration (TOCin) before measuring the BODs concentration and the organic carbon concentration (TOCout) after measuring the BODs concentration, and the biosensor output (S) of the BODs measuring device for each of the standard solution and the sample solution and index data extractor for extracting index data relating to the BOD ₅ concentrations from aging data, of the standard solution and the sample solution A change rate calculation unit that calculates the TOC decomposition rate based on the organic carbon concentration (TOCin, TOCout) before and after measuring the BODs concentration, and the TOC decomposition rate and index data calculated for each of the standard solution and the sample solution, A conversion index data calculation unit that calculates conversion index data converted into index data when all organic carbon contained in the standard solution and sample solution is decomposed based on the A BOD ₅ calculating unit that calculates the BOD ₅ concentration based on the BOD ₅ concentration may be provided.

In the approximate BOD ₅ measuring apparatus of the present invention, data related to the organic carbon concentration before and after measuring the BODs concentration may be measured by any of a TOC meter, a TOD meter, a COD meter, and an absorbance detector. .

In addition, the approximate BOD ₅ measuring apparatus of the present invention uses, as the index data, the integrated value of the biosensor output in the region where the biosensor output (S) immediately after the start of measurement for each of the standard solution and the sample solution linearly changes with time. You may do it.

Further, the approximate BOD ₅ measurement device of the present invention may alternately perform BODs concentration measurement for the standard solution and BODs concentration measurement for the sample solution in the BODs concentration measurement by the BODs measurement device.

Moreover, water quality monitoring apparatus of the present invention made from a different aspect, an approximate BOD ₅ measuring device described above, a sample fluid collecting part for sending and collecting a sample liquid from a water source to the BOD ₅ measuring apparatus, BOD ₅ measurement device The water quality of the water source is monitored based on the value of the BOD ₅ concentration calculated by the above, and a water quality monitoring unit that outputs the monitoring result is provided.
According to this, since the BOD ₅ concentration can be measured quickly and accurately using the above-described approximate BOD ₅ measuring device, the water quality is monitored with a time difference of about 1 hour for the sample liquid supplied from the sample liquid supply unit. It is possible to provide a water quality monitoring device capable of performing the above.

Further, the wastewater treatment system of the present invention made from another point of view includes an approximate BOD ₅ measuring device as described above, a wastewater treatment device for treating wastewater supplied from the outside, and collecting BOD from the wastewater treatment device. _A sample solution collecting unit to be sent to the ₅ measuring device as a sample solution, a water quality monitoring unit for monitoring the water quality of the waste water based on the value of BOD ₅ calculated by the BOD ₅ measuring device, and a monitoring result output from the water quality monitoring unit A wastewater treatment control unit that controls the operation of the wastewater treatment apparatus based on the output is provided.
According to this, since the BOD ₅ concentration can be measured quickly and accurately using the above-mentioned approximate BOD ₅ measuring device, the waste water of the waste water treatment device is collected from the sample liquid supply unit and the BOD ₅ measuring device is used. The BOD ₅ concentration is measured within a short time of about 1 hour, the water quality monitoring unit outputs the monitoring result based on the measured BOD ₅ concentration, and the waste water treatment control unit is configured to treat the waste water based on the output result of the water quality monitoring unit. Appropriate control of the device can be performed.

(Measurement of TOC decomposition rate)
First, in order to understand the arithmetic processing in the approximate BOD ₅ measurement method of the present invention, the TOC decomposition rate measured for each standard solution and sample solution and the analysis result thereof will be described.

The BODs concentration obtained by a conventional BODs measuring apparatus does not necessarily match the BOD ₅ concentration, and the value varies greatly depending on the presence of the contained organic compound.
Therefore, in order to elucidate this reason, the standard solution and the sample solution supplied to the flow cell for measuring the BODs concentration are all collected by a collector installed at the outlet of the flow cell, and it is the main component of BOD. Airframe carbon concentration was measured separately at the flow cell inlet and outlet, and the TOC decomposition rate was calculated by the following equation (2).

TOC decomposition rate = {[(Inlet concentration (TOCin) × Coefficient (K)) − (Outlet concentration (TOCout) −Blank concentration)] / (Inlet concentration (TOCin) × Coefficient (K))} × 100 (2)
Here, the coefficient K is a value obtained by incorporating a dilution rate with a phosphate buffer as a coefficient (for example, K = 8.8 / (when flowing in a standard solution of 8.8 ml / 5 minutes and a phosphate buffer solution of 2.8 ml / 5 minutes). 8.8 + 2.8)), and the blank concentration is the TOC concentration in the case of only phosphate buffer.

  Table 1 shows the calculation results of the TOC decomposition rate for a plurality of different sample solutions. From these measurement results, it was found that neither the standard solution nor the sample solution had a constant TOC decomposition rate and was not completely oxidized and decomposed.

The following two points can be cited as reasons why the TOC decomposition rate is not constant and the oxidative decomposition is not complete (the biodegradation reaction is not completed).
(1) The BODs measuring device measures the oxygen consumption for 5 minutes while supplying the standard solution and the sample solution to the flow cell, but this time is too short as a biodegradation reaction time. (On the other hand, in BOD ₅ measurement, the amount of oxygen consumed for 5 days with the biodegradation of organic carbon in the sample is measured, so the biodegradation reaction is considered to be almost complete. ).
(2) The degree of difficulty in biodegradation varies depending on the type of organic substance contained in the sample and the degree of familiarity with these fixed microorganisms. Therefore, it is not constant.

In other words, at the BODs concentration measured by the biodegradation reaction for 5 minutes with the BODs measuring device stipulated in JIS K3602, the biodegradation reaction by microorganisms is not necessarily completed, and it is included in the standard solution or sample solution. It is considered that the fact that the decomposition rate of the body carbon varies from measurement to measurement and is not constant affects the discrepancy between the BODs concentration and the BOD ₅ concentration.

Therefore, in order to use this analysis result in reverse, it is conceivable to actively utilize the TOC decomposition rate and convert the obtained BODs concentration to a value when the biodegradation reaction is completely completed.
First, the original BODs concentration measured by the biodegradation reaction for 5 minutes (that is, the BODs concentration according to the official method defined in JIS K3602) is used as index data for conversion calculation, and this is used by using the TOC decomposition rate. As a result of calculating the converted BODs concentration (trial BODs concentration) converted when the body carbon was decomposed 100%, the relationship between the converted BODs concentration and the BOD ₅ concentration was improved. However, since the degree of coincidence is still not sufficient, it was desired to further increase the degree of coincidence.

Therefore, as an index data for making it possible to obtain data having a high degree of coincidence with the BOD ₅ concentration, trials and errors are made as to what values are appropriate, and biologics generated by measuring the BODs concentration are obtained. As a result of examining the output of the sensor, it is experimentally shown that the difference in the TOC decomposition rate (biodegradation reaction rate) of the standard solution and the sample solution appears most in the initial linear portion of the biosensor output change curve over time. I found it. That is, it has been found that data having a high degree of coincidence with the BOD ₅ concentration can be obtained by using the integral value of the linear portion of the time-varying curve as index data and converting the index data using the TOC decomposition rate.

From the above, measurement of BODs concentration (biosensor output measurement) using a BODs measuring device and a TOC meter, measurement of organic carbon concentration in the sample solution, measurement of BODs concentration, and BODs concentration were measured. In combination with later measurement of organic carbon concentration in the standard solution and sample solution, a calculation method for the approximate BOD ₅ concentration was established by performing arithmetic processing in the following steps.

(Approximate BOD ₅ measurement method)
The measurement method for measuring the approximate BOD ₅ concentration consists of the following steps.
(A) Using a collection device on the outlet side of the BODs measurement device, collect the standard solution and the sample solution discharged from the flow cell in the process of measuring the BODs concentration.
(B) The TOC concentration of the standard solution and the sample solution and the TOC concentration of the standard solution and the sample solution collected in (a) are measured, and the TOC decomposition rate is calculated using the equation (2).

  (C) In measuring the BODs concentration, the time-dependent change data of the biosensor output of the standard solution and the sample solution is captured by a data collection device (for example, NR-1000 manufactured by Keyence Corporation), and the biosensor output is obtained from the acquired time-change data Extract the output of the initial part where changes linearly. Let A be the start point and B be the end point of the extracted straight line portion. Further, the required time C between A and B is obtained for each of the standard solution and the sample solution. The points A and B will be described with reference to the drawings.

  FIG. 6 is a diagram showing an example of biosensor output temporal change data for the standard solution and the sample solution. In the figure, the horizontal axis indicates the number of data acquisition points at regular intervals, and indicates the time axis. The vertical axis represents the output of the biosensor. Here, there is a baseline near 2.1 V, and the output shifts downward as the output of the biosensor decreases.

When the measurement cycle (the same measurement cycle as in FIG. 3) is started, both the standard solution and the sample solution change linearly from around 2.1 V of the baseline, and after a while, the slope becomes a curve. When the supply of the standard solution and the sample solution is stopped and the washing water is supplied when 5 minutes have elapsed, the output returns to the baseline again.
In this figure, two points of a start point A and an end point B are determined in a region where the output at the beginning of measurement changes linearly (region surrounded by a broken line), and an elapsed time C between the two points is obtained.
Note that the operation of extracting the straight line portion from the temporal change data can be automatically performed by data processing software.

(D) As data related to the BOD ₅ concentration for the standard solution and the sample solution, the index area D defined by the following equation (3) (that is, the bio in the region where the biosensor output immediately after the measurement starts linearly changes with time) The integral value of the sensor output) is calculated and used as index data for conversion calculation described later.
D = (A−B) × C / 2 (3)

(E) The conversion index area (converted index data) E converted when the standard solution and the sample solution are decomposed 100% using the TOC (TOD is acceptable) decomposition rate is calculated by the following equation (4).
E = (100 / TOC decomposition rate) × (area (D)) (4)

(F) The calculated BOD ₅ concentration F is calculated using the following equation (5) from the conversion index area E (conversion index data) of the standard solution and the sample solution obtained in (e).
F = (Conversion index area of sample solution (Espl) / Conversion index area of standard solution (Estd)) × 20 [mg / L] (5)

In this measurement method, the order of measuring the BODs concentration, the standard solution (before measuring BODs), and the sample solution may be either first or may be performed in parallel.
Moreover, it is preferable to perform the BODs concentration measurement of the standard solution and the sample solution alternately. This is because the effect of the previous biodegradation reaction tends to remain as a history as a biosensor property, so be sure to insert the measurement with the standard solution before the measurement with the sample solution as much as possible. This is to eliminate it.

  In the above-described method, the TOC concentration is measured using a TOC meter. Alternatively, the TOD concentration may be measured using a TOD meter. In short, it is sufficient that the amount of organic carbon can be mainly obtained, and other detectors such as an absorbance detector and a COD concentration detector may be substituted.

(Approximate BOD ₅ measuring device)
Next, an embodiment of an approximate BOD ₅ measuring apparatus for implementing the above-described approximate BOD ₅ measuring method will be described with reference to the drawings.

FIG. 1 is a diagram showing a configuration of an approximate BOD ₅ measuring apparatus according to an embodiment of the present invention. The approximate BOD ₅ measuring device 1 mainly includes a BODs measuring device 10, a collector 12, a TOC meter 13, an air pump 14, a fluid supply unit 20, and a data processing device 30.

  The BODs measuring apparatus 10 measures BODs concentration based on the BODs concentration measuring method described in JIS K3602, and includes a biosensor 11. The biosensor 11 has a structure in which a microbial membrane at the tip of the biosensor and an oxygen electrode are combined, and the microbial membrane is mounted in the flow cell. When the liquid containing the organic substance is supplied to the flow cell, it comes into contact with the microbial membrane, and the organic substance is decomposed. Dissolved oxygen is consumed during the microbial decomposition, and the oxygen electrode detects the current generated along with the oxygen consumption and outputs it as an output signal (S). Here, BF-2000 manufactured by Oji Scientific Instruments Co., Ltd. is used as the BODs measuring device 10.

In addition, the microbial membrane used for the biosensor 11 prepares the activated sludge of the wastewater to be treated from the culture. For example, 1 L of waste water is collected from the waste water system to be treated, 1.5 mg each of glucose and glutamic acid, buffer solution (pH 7.2, solution A) described in JIS K 0102, magnesium sulfate solution (solution B), chloride Add 2 ml each of calcium solution (solution C) and iron chloride (III) solution (solution D), and incubate for about 15 hours under aeration at 25 ° C. while maintaining the pH near neutral, and then centrifuge the culture solution Then, a precipitate is obtained, and this precipitate is suspended in waste water of the same waste water system. Such a culture process is repeated three times to obtain a culture of activated sludge.
Then, a microbial membrane of the biosensor is prepared by fixing a trace amount of the culture to a fixed membrane such as a porous membrane filter.

The collector 12 collects the standard solution 21 after measuring BODs from the liquid (standard solution, sample solution, washing water, and phosphate buffer solution flows) flowing out from the BODs measuring device 10 or after measuring BODs. Sample liquid 23 is collected.
The collector 12 prepares the standard solution collection and the sample solution collection separately, and collects the standard solution and the sample solution separately by a container switching mechanism (not shown).
In addition, while the washing water 22 is flowing out, it is discarded outside by operating the switching valve 40.

The TOC meter 13 measures the amount of organic carbon in the liquid to be measured, and specifically uses TOC-5000 manufactured by Shimadzu Corporation.
Here, first, the TOC concentrations of the standard solution 21 stock solution and the sample solution 23 stock solution are measured. This TOC concentration is handled as the TOC concentration (TOCin) before the BODs measurement in the BODs measuring apparatus 10.

  The TOC meter 13 also measures the TOC concentration of the standard solution collected in the collector 12 and the sample solution collected in the collector 12. This TOC concentration is handled as the TOC concentration (TOCout) after the BOD measurement in the BODs measuring device 10.

The fluid supply unit 20 includes a standard solution 21 (glucose / glutamic acid solution, BOD ₅ concentration is 20 [mg / L]), washing water 22 and a sample solution 23. These liquids are prepared by appropriately driving the valves 25, 26, 27 and the pump 28, and are supplied to the BODs measuring device 10. Further, a phosphate buffer solution 24 is prepared in the liquid supply unit 20 and is always supplied by a pump 29. Phosphate buffer is used for microbial membrane activity.
The air pump 14 is connected to a flow path between the fluid supply unit 20 and the BODs measuring apparatus 10 and supplies oxygen used for decomposing organic carbon by microorganisms by constantly aeration.

When measuring the standard solution 21, the valve 25 is opened, the pump 28 is driven, and the pump 29 that sends the phosphate buffer solution 24 is further driven, so that the mixed liquid having a flow ratio determined by the rotational speed of both pumps is reduced to BODs. Supplied to the measuring device 10.
Similarly, when measuring the sample solution 23, the valve 26 is opened, the pump 28 is driven, and the pump 29 for feeding the phosphate buffer solution 24 is driven.
When cleaning the BODs measuring apparatus 10, cleaning water is supplied by opening the valve 26 and driving the pump 28.
The fluid supply unit 20 is connected to the TOC meter 13 so that the standard solution 21 and the sample solution 23 are supplied.

For each of the standard solution 21 and the sample solution 23, the data processing device 30 outputs the output (S) from the biosensor 11, the TOC concentration (TOCin) before the BODs concentration measurement from the TOC meter 13, and the BODs concentration after the measurement. Calculation processing is performed based on each data of the TOC concentration (TOCout).
Specifically, the data collection system NR-1000 manufactured by Keyence that samples the output (S) of the biosensor 11 of the BODs measurement apparatus 10 and a general-purpose personal computer that performs calculations based on the acquired data are configured.

When the operations executed by the data processing device 30 are further classified into functions, the index data extraction unit 31, the change rate calculation unit 32, the conversion index data calculation unit 33, and the BOD ₅ calculation unit 34 can be classified. it can.

  The index data extraction unit 31 performs an operation of extracting index data from the output (S) of the biosensor 11 of the BODs measurement device 10 for each of the standard solution and the sample solution. That is, the index area D defined by the above-described equation (3) (the integrated value of the biosensor output in a region where the biosensor output immediately after the start of measurement linearly changes with time) is calculated as index data.

  The change rate calculation unit 32 calculates the TOC decomposition rate defined by the above-described equation (2) based on the organic carbon concentration (TOCin, TOCout) before and after the BODs measurement for each of the standard solution and the sample solution.

  The conversion index data calculation unit 33 calculates a conversion index area (converted index data) E based on the above-described equation (4) for each of the standard solution and the sample solution.

The BOD ₅ calculation unit 34 calculates the calculated BOD ₅ concentration F from the conversion index areas (conversion index data) of the standard solution and the sample solution using the above-described equation (5).

  Next, the measurement operation by the approximate BODs measurement apparatus 1 will be described with reference to the flowchart shown in FIG.

st101:
The standard solution 21 and the phosphate buffer solution 24 are sent to the BODs measuring apparatus 10 and BODs measurement is performed. The output (S) of the biosensor 11 at this time is measured.
st102:
The data processing device 30 calculates and stores the index area (Dstd) from the output (S) based on the equation (3).

st103:
The standard solution 21 is sent to the TOC meter 13, and the organic carbon concentration (TOCin) in the standard solution is measured and stored. This measurement is performed in parallel with s101.
st104:
After the total amount of the standard solution after the BODs concentration is measured in s101 is collected in the collector 12 on the outlet side of the BODs measuring device 10, the residual organic carbon concentration (TOCout) in the standard solution is measured.
st105:
Based on the organic carbon concentration (TOCin, TOCout) measured in st103 and st104, the TOC decomposition rate of the standard solution is calculated and stored.

st106:
The sample solution 23 and the phosphate buffer solution 24 are sent to the BODs measuring apparatus 10 and BODs measurement is performed. The output (S) of the biosensor 11 at this time is measured.
st107:
The data processor 30 calculates and stores the index area (Dspl) from the output (S) based on the equation (3).

st108:
The sample solution 23 is sent to the TOC meter 13, and the organic carbon concentration (TOCin) in the sample solution is measured and stored. This measurement is performed in parallel with s106.
st109:
After the total amount of the sample liquid 23 after the BODs concentration is measured in s106 is collected in the collector 12 on the outlet side of the BODs measuring device 10, the residual organic carbon concentration (TOCout) in the sample liquid is measured. .

st110:
Based on the organic carbon concentration (TOCin, TOCout) measured in st108 and st109, the TOC decomposition rate of the sample solution is calculated based on the equation (2).
st111:
Using Dstd obtained in st102, st105, st107, and st110, the TOC decomposition rate of the standard solution, Dspl, and the TOC decomposition rate of the sample solution, when the TOC decomposition rate is 100% based on the equation (4) The converted conversion index areas Estd (standard solution) and Espl (sample solution) are calculated.
st112:
Based on the equation (5), the calculated BOD ₅ concentration is calculated using the converted sample areas Estd and Espl calculated in st111.

By sequentially executing the above operations, the BOD ₅ concentration can be calculated within a short time (about 1 hour).

(Measurement example)
Next, a measurement example using the above-described approximate BOD ₅ measuring apparatus will be described.
Sample liquids were collected over a period of several days, and organic compounds that affect BODs measurement were added irregularly, and BOD ₅ concentrations measured for these sample liquids by the official method prescribed in JIS K0102 The BODs concentration measured by the official method specified in JIS K3602 and the calculated BOD ₅ concentration obtained by the approximate BOD ₅ measuring device of the present invention were measured and compared. About each sample liquid, it measured also about the organic solvent contained by the gas chromatography method.

The measurement results are shown in Table 2. Further, the relationship between the BODs concentration and the BOD ₅ concentration is shown in FIG. 7, and the relationship between the calculated BOD ₅ concentration and the BOD ₅ concentration is shown in FIG. 8 (in addition, each data shown in Table 2 and each data in Table 1 are The same sample number (sample No.) is the data of the same sample solution).

As can be seen in Table 2 and FIG. 7, the relationship between the BOD ₅ concentration and the BODs concentration indicates that the correlation coefficient R ² is 0.789, indicating a weak correlation. The constant indicating the slope of the linear expression when these relationships are approximately expressed by a linear expression is 5.3306, and the degree of coincidence between the BODs concentration and the BOD ₅ concentration is not good. In particular, as can be seen in FIG. 7, the three samples to which DMF was added are completely off, and organic compounds such as DMF have a great influence on the relationship between the BODs concentration and the BOD ₅ concentration.

On the other hand, as seen in Table 2 and Table 8, the relationship between BOD ₅ concentration and calculated BOD ₅ concentrations, the correlation coefficient ^{R 2} is 0.9653, indicating a strong correlation. Moreover, both are proportional and the proportionality constant shows a value very close to 1, and the degree of coincidence between the calculated BOD ₅ concentration and the BOD ₅ concentration is good. Therefore, the calculated BOD ₅ concentration measured and calculated by the approximate BOD ₅ measuring apparatus of the present invention can be regarded as the BOD ₅ concentration, and can be used for monitoring a wastewater treatment facility.

(Water quality monitoring equipment and wastewater treatment equipment)
Next, a water quality monitoring apparatus and a wastewater treatment system to which an approximate BOD ₅ measuring apparatus according to another embodiment of the present invention is applied will be described with reference to FIG. The wastewater treatment system 50 includes a water quality monitoring device 60, a wastewater treatment control unit 64, and a wastewater treatment device 70.

The water quality monitoring device 60 includes an approximate BOD ₅ measurement device 61, a water quality monitoring unit 62, and a sample solution collecting unit 63.

The approximate BOD ₅ measuring device 61 is the same as the approximate BOD ₅ measuring device 1 of FIG. 1, and the waste water collected from the waste water treatment device 70 (water source) can be used as the sample liquid 23 as will be described later. The liquid 23 can be measured at intervals of at least one hour.

The water quality monitoring unit 62 monitors the water quality based on the measurement result of the calculated BOD ₅ concentration obtained by the approximate BOD ₅ measuring device 61. For example, the reference value of the calculated BOD ₅ concentration and the allowable fluctuation range, which are judgment criteria, are memorized, the monitoring is continuously performed to compare the measurement result with these reference values, the measurement value is output at any time, and the measurement value is Water quality is monitored by outputting an alarm signal when the reference value is exceeded or the allowable fluctuation range is exceeded within a certain period.

The sample solution collecting unit 63 is configured by a piping channel for collecting waste water from the waste water treatment device 70 and sending it to the fluid supply unit 20 (see FIG. 1) of the approximate BOD ₅ measuring device 61.

  The wastewater treatment control unit 64 receives monitoring results such as measurement values and alarm signals output from the water quality monitoring unit 62, and sends an appropriate control signal to the wastewater treatment device 70 based on the monitoring results.

  The wastewater treatment apparatus 70 includes a wastewater storage tank 71, a wastewater treatment tank 72, a sedimentation tank 73, a dilution water storage tank 74, a pipe 75 that connects the wastewater outlet of the factory and the wastewater storage tank 71, a wastewater storage tank 71, A pipe 76 that connects the wastewater treatment tank 72 to the flow path, a pipe 77 that connects the wastewater treatment tank 72 and the sedimentation tank 73 to the flow path, a pipe 78 that discharges waste water from the sedimentation tank 73, and a wastewater storage tank from the dilution water storage tank 74 A pipe 79 for supplying dilution water to 71, a flow control valve 81 provided in the middle of the pipe 76, a three-way valve 82 with a flow control function provided in the middle of the pipe 78, and provided in the middle of the pipe 79. The flow control valve 83, the three-way valve 82, and the wastewater treatment tank 72 are constituted by a return pipe 80 that connects the flow paths. The flow control valve 81, the three-way valve 82, and the flow control valve 83 are controlled by a control signal from the wastewater treatment control unit 64.

In this wastewater treatment system 50, wastewater from a wastewater outlet of a factory or the like is led to a wastewater storage tank 71 via a pipe 75, and the wastewater treatment tank is passed from the wastewater storage tank 71 via a pipe 76 and a flow rate control valve 81 according to the processing amount. 72.
In the wastewater treatment tank 72, wastewater is treated using activated sludge. The treated waste water is sent to the sedimentation tank 73 through the pipe 77. The treated water staying in the settling tank 73 for a certain time is discharged to the outside through the pipe 78 and the three-way valve 82.

Part of the wastewater flowing through the pipe 76 of the wastewater treatment device 70 is collected by the sample collection unit 63 and sent to the BOD ₅ measurement device 61. The sample collection unit 63 collects a sample from an appropriate position such as the pipe 78, the waste water treatment tank 72, the vicinity of the outlet side of the three-way valve 82 (external discharge port) in addition to the pipe 76 in accordance with the measurement purpose. It may be.

The wastewater sent to the approximate BOD ₅ measuring device 61 is measured in about one hour, the calculated BOD ₅ concentration is calculated, and sent to the water quality monitoring unit 62.
The water quality monitoring unit 62 outputs the measurement result of the calculated BOD ₅ concentration to the wastewater treatment control unit 64 at any time. Further, the reference value stored in advance is compared with the current measurement value, and the measurement value is An alarm signal is output when the reference value is exceeded.

The wastewater treatment control unit 64 outputs a control signal to the flow rate adjustment valve 81, the three-way valve 82, and the flow rate adjustment valve 83 based on the monitoring result such as an alarm signal sent from the water quality monitoring unit 62.
When the control signal to the flow rate control valve 81 is output, the flow of waste water from the waste water storage tank 71 to the waste water treatment tank 72 is increased or decreased or stopped.
When the control signal is output to the three-way valve 82, the discharge to the outside (public water area) is stopped, or the treated water is returned to the wastewater treatment tank 72 via the return pipe 80.
When a control signal is output to the flow rate adjustment valve 83, dilution water is added from the dilution water storage tank 74 to the waste water storage tank 71, and the waste water in the waste water storage tank 71 is diluted.

According to the present invention, since the approximate BOD ₅ concentration can be measured quickly and accurately, the approximate BOD ₅ concentration (calculated BOD concentration) that can be regarded as the original BOD ₅ concentration is obtained in real time. Can do. Further, it can be utilized in providing the approximate BOD ₅ measuring apparatus using the approximation BOD concentrations. Moreover, such a water quality monitoring system that applies the approximate BOD ₅ measuring apparatus can be utilized in providing a wastewater treatment system.

Shows the structure of approximate BOD ₅ measuring apparatus according to an embodiment of the present invention. Shows a water quality monitoring device and the wastewater treatment system configuration which applies the approximate BOD ₅ measuring apparatus according to an embodiment of the present invention. The figure explaining the measurement cycle by a BODs measuring device. The figure which shows a time-dependent change of a biosensor output. The flowchart at the time of the measurement by the approximate BOD ₅ measuring apparatus. The figure explaining the time-dependent change of biosensor output, and index data. Diagram showing the relationship between the BODs and BOD _5. Diagram showing the relationship between BOD ₅ (calculated BOD ₅₎ from BOD ₅ and BODS.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Approximate BOD ₅ measuring apparatus 10 BODs measuring apparatus 11 Biosensor 12 Collector (collecting part)
DESCRIPTION OF SYMBOLS 13 TOC meter 20 Fluid supply part 21 Standard solution 23 Sample solution 30 Data processing device 31 Index data calculation part 32 Change rate calculation part 33 Conversion index data calculation part 34 BOD ₅ calculation part 50 Waste water treatment system 60 Water quality monitoring apparatus 61 Approximate BOD ₅ Measuring device 62 Water quality monitoring unit 63 Sample liquid sampling unit 64 Wastewater treatment control unit 70 Wastewater treatment device

Claims (14)

Obtaining time-dependent data of biosensor output (S) at the time of measuring BODs concentration by a BODs measuring device using a biosensor for each of a standard solution with a known BOD ₅ concentration and a sample solution to be measured,
For each of the standard solution and the sample solution, data related to changes in the organic carbon concentration before and after the BODs concentration measurement by the BODs measuring device is obtained,
Index data related to BOD ₅ concentration is extracted from the time course data of biosensor output (S) for each of the standard solution and the sample solution,
Conversion index data converted into index data when all the organic carbon contained in the standard solution and sample liquid is decomposed based on the index data and data related to changes in the organic carbon concentration for each standard solution and sample solution Calculate
An approximate BOD ₅ measurement method, wherein the BOD ₅ concentration is calculated based on the respective conversion index data of the standard solution and the sample solution. Obtaining time-dependent data of biosensor output (S) at the time of measuring BODs concentration by a BODs measuring device using a biosensor for each of a standard solution with a known BOD ₅ concentration and a sample solution to be measured,
For each of the standard solution and the sample solution, data related to the organic carbon concentration before and after the BODs concentration measurement by the BODs measuring device is measured,
Index data related to BOD ₅ concentration is extracted from the time-dependent data of biosensor output (S) for each of the standard solution and the sample solution,
Calculate the TOC decomposition rate based on the data related to the organic carbon concentration before and after measuring the BODs concentration for each of the standard solution and the sample solution,
Based on the TOC decomposition rate and the index data for each of the standard solution and the sample solution, calculated conversion index data converted into index data when all the organic carbon contained in the standard solution and the sample solution is decomposed,
An approximate BOD ₅ measurement method, wherein the BOD ₅ concentration is calculated based on the respective conversion index data of the standard solution and the sample solution. Obtaining time-dependent data of biosensor output (S) at the time of measuring BODs concentration by a BODs measuring device using a biosensor for each of a standard solution with a known BOD ₅ concentration and a sample solution to be measured,
For each of the standard solution and the sample solution, the organic carbon concentration (TOCin) before measuring the BODs concentration by the BODs measuring device is measured with a TOC meter.
The organic carbon concentration (TOCout) of each of the standard solution and the sample solution after measuring the BODs concentration with a BODs measuring device is measured with a TOC meter.
Index data related to BOD ₅ concentration is extracted from the time-dependent data of biosensor output (S) for each of the standard solution and the sample solution,
Based on the organic carbon concentration (TOCin, TOCout) before and after measuring the BODs concentration for each of the standard solution and the sample solution, the TOC decomposition rate is calculated,
Based on the TOC decomposition rate and the index data for each of the standard solution and the sample solution, calculated conversion index data converted into index data when all the organic carbon contained in the standard solution and the sample solution is decomposed,
An approximate BOD ₅ measurement method, wherein the BOD ₅ concentration is calculated based on the respective conversion index data of the standard solution and the sample solution. 3. The approximation according to claim 1, wherein the data related to the organic carbon concentration before and after the measurement of the BODs concentration is measured by any one of a TOC meter, a TOD meter, a COD meter, and an absorbance detector. BOD measurement method. The integrated value of the biosensor output in a region where the biosensor output (S) immediately after the start of measurement for each of the standard solution and the sample solution linearly changes with time as the index data. Approximate BOD ₅ measurement method according to claim 1. 6. The BOD ₅ concentration measurement according to claim 1, wherein the BODs concentration measurement by the BODs measuring device alternately performs BODs concentration measurement for a standard solution and BODs concentration measurement for a sample solution. Method. A fluid supply unit for supplying a plurality of fluids including at least a standard solution having a known BOD ₅ concentration and a sample solution to be measured;
A BODs measuring device for measuring the BODs concentration of each of the standard solution and the sample solution using a biosensor;
A collection unit for collecting the standard solution and the sample solution after the BODs concentration is measured by the BODs measurement device;
A detector for measuring data related to the organic carbon concentration before measuring the BODs concentration by the BODs measuring device of each of the standard solution and the sample solution, and data related to the organic carbon concentration after measuring the BODs concentration;
An index data extraction unit that extracts index data related to the BOD ₅ concentration from the time-dependent change data of the biosensor output (S) of the BODs measurement device for each of the standard solution and the sample solution;
For each of the standard solution and the sample solution, converted into index data when all the organic carbon contained in the standard solution and sample solution is decomposed based on the data related to the organic carbon concentration before and after the BODs concentration measurement and the index data. A conversion index data calculation unit for calculating the converted conversion index data,
Standards and approximate BOD ₅ measuring apparatus characterized by comprising a BOD ₅ calculation unit for calculating a BOD ₅ concentration based on each conversion index data of the sample solution. A fluid supply unit for supplying a plurality of fluids including at least a standard solution having a known BOD ₅ concentration and a sample solution to be measured;
A BODs measuring device for measuring the BODs concentration of each of the standard solution and the sample solution using a biosensor;
A collection unit for collecting the standard solution and the sample solution after the BODs concentration is measured by the BODs measurement device;
A detector for measuring data related to the organic carbon concentration before measuring the BODs concentration by the BODs measuring device of each of the standard solution and the sample solution, and data related to the organic carbon concentration after measuring the BODs concentration;
An index data extraction unit that extracts index data related to the BOD ₅ concentration from the time-dependent change data of the biosensor output (S) of the BODs measurement device for each of the standard solution and the sample solution;
A change rate calculation unit for calculating a TOC decomposition rate based on data related to organic carbon before and after measuring the BODs concentration for each of the standard solution and the sample solution;
Conversion index data calculation that calculates conversion index data converted into index data when all organic carbon contained in the standard solution and sample liquid is decomposed based on the TOC decomposition rate and the index data for each of the standard solution and the sample solution And
Standards and approximate BOD ₅ measuring apparatus characterized by comprising a BOD ₅ calculation unit for calculating a BOD ₅ concentration based on each conversion index data of the sample solution. A fluid supply unit for supplying a plurality of fluids including at least a standard solution having a known BOD ₅ concentration and a sample solution to be measured;
A BODs measuring device for measuring the BODs concentration of each of the standard solution and the sample solution using a biosensor;
A collection unit for collecting the standard solution and the sample solution after the BODs concentration is measured by the BODs measurement device;
A TOC meter for measuring the organic carbon concentration (TOCin) before measuring the BODs concentration and the organic carbon concentration (TOCout) after measuring the BODs concentration by the BODs measuring device of each of the standard solution and the sample solution;
An index data extraction unit that extracts index data related to the BOD ₅ concentration from the time-dependent change data of the biosensor output (S) of the BODs measurement device for each of the standard solution and the sample solution;
A change rate calculation unit that calculates a TOC decomposition rate based on organic carbon concentrations (TOCin, TOCout) before and after measuring the BODs concentration for each of the standard solution and the sample solution;
Conversion index for calculating conversion index data converted to index data when all organic carbon contained in the standard solution and sample liquid is decomposed based on the TOC decomposition rate and index data calculated for each of the standard solution and the sample solution A data calculator;
Standards and approximate BOD ₅ measuring apparatus characterized by comprising a BOD ₅ calculation unit for calculating a BOD ₅ concentration based on each conversion index data of the sample solution. 9. The approximation according to claim 7, wherein the data related to the organic carbon concentration before and after the BODs concentration measurement is measured by any one of a TOC meter, a TOD meter, a COD meter, and an absorbance detector. BOD measuring device. 11. The integrated value of the biosensor output in a region where the biosensor output (S) immediately after the start of measurement for each of the standard solution and the sample solution linearly changes with time as the index data. An approximate BOD ₅ measuring device according to claim 1. BODs concentration measurement according BODs measuring apparatus, BOD ₅ measuring apparatus according to any one of claims 7 to 11 characterized in that the BODs concentration measurement for BODs concentration measurement and the sample solution for the standard solution alternately. The BOD ₅ measuring device according to any one of claims 7 to 12,
A sample solution collecting unit for collecting a sample solution from a water source and sending it to the BOD ₅ measuring device;
A water quality monitoring apparatus comprising: a water quality monitoring unit that monitors water quality of a water source based on a BOD ₅ concentration value calculated by a BOD ₅ measurement apparatus and outputs a monitoring result. The BOD ₅ measuring device according to any one of claims 7 to 12,
Wastewater treatment equipment for treating wastewater supplied from outside;
A sample liquid collecting unit that collects waste water from the waste water treatment apparatus and sends it to the BOD ₅ measuring apparatus as a sample liquid;
A water quality monitoring unit that monitors the quality of waste water based on the value of BOD ₅ calculated by the BOD ₅ measuring device, and outputs a monitoring result;
A wastewater treatment system comprising: a wastewater treatment control unit that controls operation of a wastewater treatment apparatus based on an output from a water quality monitoring unit.

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