JPH10142195A - Bod sensing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the prediction of exchange time of a diaphragm with reliability by determining that it is time for exchanging the film in the case that the detected value of a BOD(biochemical oxygen demand) detecting device is smaller than a set value and that it is not time in the case that it is larger than the set value. SOLUTION: In a BOD detector 22, neutrality is maintained by putting a buffer solution in a measurement cell for which a film on which microorganisms are fixed is provided, the inside of a container is air-saturated, and the amount of reduction of dissolved oxygen in the container is measured by the output of a diaphragm-type oxygen electrode by supplying sample water. A set-value storage part 23 stores a standard value at the time of feeding a plurality of liquids as a set value. A comparing means 24 compares a value detected by the BOD detector 22 with the set value in the set-value storage part 23. A determining means 25 determines that it is time for exchanging the film from the compared result in the case that the detected value is smaller than the set value and determines that it is not in the case that it is larger than the set value. When the exchange time of the film is determined, it is displayed on a display part 26. In this way, it is possible to prevent the false determination of exchange time of film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a BOD sensing device used for measuring biochemical oxygen demand (hereinafter referred to as BOD).

[0002]

2. Description of the Related Art Various devices have been proposed for measuring the amount of organic matter as a BOD value using a microorganism electrode. Hereinafter, a conventional BOD sensing device will be described. FIG. 9 is a schematic configuration diagram of a conventional BOD sensing device, and FIG. 10 is a detailed diagram of a BOD detection device of the conventional BOD sensing device. In FIG. 9, 1 is a microbial electrode using a membrane oxygen electrode and a microbial membrane made of yeast or the like,
A measuring cell 13 as shown in FIG. 10 is attached to the lower part of the microorganism electrode 1, and a solution described below flows from an inlet 14 of the measuring cell 13, and is supplied to an outlet 15.
From the waste liquid tank 10. As the solution to be flown here, there are a washing solution 3, a buffer solution 4, standard solutions 5a, 5b, 5c, and a sample water 6. The microbial electrode 1 and the measurement cell 13 are B
A BOD detection device for measuring OD is configured.
The surroundings of the microbial electrode 1 and the measurement cell 13 are warmed by warm water and maintained at a predetermined temperature. When the amount of decrease in dissolved oxygen is measured at the microbial electrode 1 by flowing the sample water 6 as the liquid to be measured, an output current is output. By measuring the output current, a corresponding BOD value is calculated by a calculation means (not shown), This BOD value is displayed on the display unit 9 composed of a liquid crystal panel or the like. Measurement cell 13 of BOD detector
The solution to be injected into the liquid is injected using the pump 7, but by switching the switching valve 2 according to a preset procedure, the washing liquid 3, the buffer 4, the standard liquid 5a,
b, 5c, and the solution of the sample water 6 are sequentially selected and injected.

Next, the details of the BOD detecting device will be described. As shown in FIG. 10, the microbial electrode 1 is composed of a diaphragm type oxygen electrode 11 and a microbial membrane 12 using yeast or the like. A measuring cell 13 is provided below the microbial electrode 1, and a cleaning solution 3, a buffer solution 4, standard solutions 5 a, 5 b, 5 c, and a sample water 6 are injected from an inlet 14 of the measuring cell 13 in a predetermined order. After the measurement, each is discharged from the discharge port 15 to the waste liquid tank 10. As described above, the microbial electrode 1 and the measurement cell 13 which constitute the BOD detection device are
The cleaning water 3, the buffer 4, the standard solutions 5a, 5b, 5c, and the sample water 6 are kept at a predetermined temperature by the warm water in the sample 6. Since the microbial membrane 12 using yeast or the like is installed on the microbial electrode 1, an air pump 8 for supplying air by mixing the solution into the solution so that the microorganisms constituting the microbial membrane 12 can breathe is provided. Is provided.

The operation of the conventional BOD sensing device described above will now be described. Conventional BOD sensing devices include a washing solution 3, a buffer solution 4, standard solutions 5a, 5b, 5c,
A time program that determines in what order the sample water 6 is injected is prepared in advance. For example, when the measurement cycle is 60 minutes, the sample water 6 is injected for 10 minutes,
Thereafter, the cleaning liquid 3 is injected for 50 minutes. When measurement is not performed, it is set that the washing solution 3 and the buffer solution 4 are respectively injected. According to such a time program, first, the switching valve 2 is manually switched to open the valve of the buffer solution 4. At this time, other valves, for example, the valve for the cleaning liquid 3 remain closed. As a result, the neutral buffer 4 is supplied to the measuring cell 13 by the pump 7. Thereafter, the switching valve 2 is switched to supply the cleaning liquid 4 to the measuring cell 13. Since the yeast constituting the microbial membrane 12 is breathing, the air is constantly supplied to the BOD detector by the air pump 8. When the measurement is performed, the switching valve 2 is switched to select the standard solution 5a, and this is supplied to the measuring cell 13 by the pump 7.
To supply. The oxygen concentration of the standard solution 5a in the measurement cell 13 is measured by the microorganism electrode 1, and is output in the form of an output current. Next, the cleaning valve 3 is selected by switching the switching valve 2 and supplied to the measuring cell 13 by the pump 7 for cleaning. After that, the above operation is performed with the standard solution 5b and the standard solution 5b.
Similarly, the output-concentration conversion ratio is corrected for c, and a calibration curve is created.

Subsequently, the sample water 6 to be measured is selected by the switching valve 2, and the measurement cell 13 is measured by the pump 7.
And the sample water 6 is supplied to the microbial electrode 1. The calculation means performs output-concentration conversion based on the calibration curve from the output current value at this time to obtain a BOD value. Then switching valve 2
Is switched to inject the cleaning liquid 3 into the measuring cell 13 for cleaning. When the measurement is to be continued, the sample water 6 to be measured is selected again by the switching valve 2, supplied to the measurement cell 13 and measured by the microorganism electrode 1. When the measurement is not performed, the cleaning liquid 3
And buffer 4 are sequentially injected.

FIG. 11 is a block diagram of a conventional BOD sensing device. Reference numeral 17 denotes an operation panel for inputting a built-in time program, switching of a solution, etc., 18 a built-in timer for counting the date and time built in the BOD sensing device, and 19 a management and setting time of the built-in timer 18. A management means 20 for managing the timer program and the timer value receives a time program setting and a solution setting input from the operation panel 17 and controls the cleaning solution 3, the buffer solution 4, the standard solutions 5a, 5b, 5c and the sample water 6. Mode switching means for sequentially selecting which solution is to be introduced into the solution introduction path and switching the mode. Reference numeral 21 denotes a switching valve for switching any one of the washing solution 3, the buffer solution 4, the standard solutions 5a, 5b, 5c, and the sample water 6 to the measurement cell 13 of the microorganism electrode 1 by the mode switching means 19. Is a valve driving means for specifically operating.

FIG. 12 is a flowchart (1) of the conventional BOD sensing device, FIG. 13 is a flowchart (2) of the conventional BOD sensing device, and FIG. 14 is a flowchart (3) of the conventional BOD sensing device. Hereinafter, description will be made with reference to the flowcharts of FIGS. 12, 13 and 14. A timer for counting the date and time is built in the BOD sensing device, and the built-in timer 18 constantly counts the date and time. First, a preset built-in time program is selected by the operation panel 17 (step 1). When the time program is not selected, there is no sample water 6 for measurement, and the measurement is not performed (step 2), the flow rate value of the solution at the time of the measurement currently set is manually adjusted to the flow rate value at the time of the non-measurement. (Ste
p3). The flow rate value at the time of non-measurement is smaller than the flow rate value at the time of measurement, and is decreased in order to flow the minimum necessary flow rate. When the measurement is carried out in the presence of the sample water 6, the mode switching means 2 is changed every time the introduction time set in the time program arrives.
0 drives the valve driving means 21, whereby the switching valve 2 is switched and introduced into the measuring cell 13. The buffer 4 is continuously introduced until the measurement is possible (step 4), and then the washing solution 3 is similarly introduced (s).
step5). This (step 4) and (step 5) can be alternately repeated. As a result, when measurement becomes possible (step 6), a calibration curve is created as follows (step 7). At this point, buffer 4
Is introduced, the washing liquid 3 is introduced by the switching valve 2 after the elapse of the preset buffer solution introduction time, and it waits until the preset washing time elapses. If is introduced, wait until the preset cleaning time has elapsed (step 8),
After that, the standard cell 5a is set by the switching valve 2 until the standard liquid introduction time set in advance elapses.
The standard solution is measured by the microorganism electrode 1 and output as a current value, and after calculation, output as a BOD value (step 10). Thereafter, the switching valve 2 is switched, and the cleaning liquid 3 is introduced into the measurement cell 13 until a predetermined cleaning time has elapsed (step 11). Thereafter, the standard solution 5b is again introduced by the switching valve 2 for the preset standard solution introduction time (step 1).
2) After being detected as a current value by the microorganism electrode 1, the current value is calculated and output as a BOD value (step 13). Thereafter, the cleaning liquid 3 is introduced by the switching valve 2 until a predetermined cleaning time has elapsed (step 14). Subsequently, the standard solution 5c is introduced into the preset standard solution introducing time by the switching valve 2 (step 15), and the current value is detected by the microbial electrode 1, and the BOD is calculated.
Output as a value (step 16). Thereafter, the switching valve 2 introduces the cleaning liquid 3 until a set predetermined cleaning time elapses (step 17). Then, the measured values detected by the standard liquids 5a, 5b, and 5c are displayed on the display unit 9 such as a liquid crystal panel. The measured value constitutes a calibration curve. When the user of the BOD sensing device determines that there is no abnormality by looking at the result (st
ep18), guide the sample water 6 and start the measurement (step 18).
p19). However, when the user determines that there is an abnormality in the calibration curve, an abnormal treatment such as replacement of the membrane is performed (step 20).

[0008]

In the conventional BOD sensing device described above, the standard solution 5a,
The output of the BOD value at the time of injecting 5b and 5c is displayed on the display unit 9.
Will be displayed. However, as described in the above (step 17), the time to replace the membrane is determined from the displayed BOD value based on the intuition and experience of the user.
If the OD value is low and the replacement time of the membrane has arrived, the judgment will be incorrect and the measurement will be performed on the membrane that exceeds the usage limit, or if the non-measurement state continues and the BOD value is not checked, the replacement will be made. Even though the time has passed, the buffer solution 4, the washing solution 3 and the like are constantly injected into the microorganism electrode 1. Therefore, if the solution has been used wastefully using the membrane whose replacement time has passed, or if the BOD value cannot be confirmed when the measurement is not performed, a preparation time for exchanging the membrane for the measurement is required. The measurement could not be performed immediately. In addition, the BOD value decreases during the measurement, and the measurement result of the sample water 6 becomes unreliable as compared with the case where the microbial membrane 12 is in a normal state. Even if the measurement cannot be continued, the measurement is continued as it is. There was a danger that.

Therefore, the present invention solves these problems in the prior art. It is possible to surely know that the membrane is about to be replaced, without wasting the solution for measurement.
It is an object of the present invention to provide a BOD sensing device that can confirm a BOD value even when measurement is not performed and does not require a preparation time for measurement.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention comprises a comparing means for comparing a detected value detected by a BOD detecting device with a predetermined set value, and a method for detecting a detected value which is lower than the set value. When the detected value is equal to or greater than the set value, the determination means determines that the replacement time of the membrane is not yet determined, and the notification means that notifies the user of the output of the determination means when the replacement time of the membrane comes. It is characterized by having.

Thus, it is possible to reliably know that the membrane is about to be replaced, and to check the BOD value without wasting the solution for measurement without wasting the solution for measurement. Eliminates the need for preparation time.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION
A BOD detection device having a measurement cell into which a solution is introduced, and a microbial membrane on which an oxygen electrode and microorganisms are fixed, and a buffer solution, a washing solution, a standard solution, or a sample water which is connected to the measurement cell and switched to be supplied. A solution supply unit capable of
Comparing means for comparing the detection value detected by the BOD detection device with a predetermined set value; and determining that it is time to replace the membrane when the detected value is lower than the set value, wherein the detected value is not less than the set value. In this case, the BOD sensing device is characterized by comprising a judgment means for judging that the time for replacing the membrane has not yet come, and a notifying means for notifying the user with an output from the judging means when the time for replacing the membrane comes. When the time for replacing the membrane comes, the user can be notified.

Further, the invention according to claim 2 is characterized in that the notification means is a display means for notifying the user that the replacement time has come, so that it can be displayed continuously, and can be used for a long time. It is suitable.

According to a third aspect of the present invention, there are a plurality of types of the standard solution, and the judging means judges the time to replace the membrane by comparing each set value of the standard solution with the detected value. A highly accurate determination can be made.

(Embodiment 1) Hereinafter, Embodiment 1 of the present invention will be described. The configuration of the conventional BOD sensing device described in FIGS. 9 and 10 basically matches the configuration of the BOD sensing device according to the first embodiment of the present invention. Therefore, the description of the BOD sensing device according to Embodiment 1 of the present invention will be omitted from the description of FIGS. 9 and 10 and will not be repeated. 1 is a microorganism electrode, 2 is a switching valve, 3 is a washing solution, 4 is a buffer solution, 5a, 5b, 5c is a standard solution, 6 is sample water, 7 is a pump, 8 is an air pump, 10 is a waste liquid tank, and 11 is a diaphragm. A type oxygen electrode, 12 is a microbial membrane, 13 is a measurement cell, 14 is an inlet, 15 is an outlet, and 16 is a hot water tank. The microbial electrode 1, the measurement cell 13, and the like constitute a BOD detection device according to the first embodiment of the present invention. Also, the measuring cell 13
Solution 3, buffer solution 4, and standard solutions 5a, 5b, 5
c, a device provided with a supply container for sample water 6, a switching valve 2 for switching between them, a pump 7 for supplying these solutions, and the like, according to the first embodiment of the present invention.
Of the solution supply unit.

FIG. 1 is a block diagram of a BOD sensing device according to one embodiment. Reference numeral 17 denotes a built-in time program, a washing solution 3, a buffer solution 4, standard solutions 5a, 5b,
5c, an operation panel capable of performing input settings such as switching of a solution of the sample water 6, etc., 18 is a built-in timer for counting the date and time built in the BOD sensing device, 19 is management of the built-in timer 18, and a set time and timer A timer management means 20 for managing the value is provided with a time program setting input from the operation panel 17 and a solution setting, and selects one of the washing solution 3, the buffer solution 4, the standard solutions 5a, 5b, 5c and the sample water 6. Mode switching means 21 for switching the mode by selecting whether the solution is introduced into the solution introduction path, and valve driving means 21 which can be switched by the mode switching means 20 to operate the switching valve 2. Reference numeral 22 denotes a microorganism membrane 12 on which microorganisms (such as yeast) are immobilized.
The buffer solution 4 is allowed to flow through the measurement cell 13 provided with the sample, and the neutral condition is maintained, and air is blown into the container to substantially maintain the air-saturated condition. This is a BOD detector that measures the amount of decrease in dissolved oxygen in the measurement cell 13 corresponding to the BOD component in the water 6, that is, the amount of dissolved oxygen consumed by metabolism of microorganisms, by detecting the output current of the diaphragm oxygen electrode. 23 is a standard solution 5a, 5b,
A set value storage unit in which a standard value in a state where the microbial membrane can be measured is stored as a set value with a detected value detected by the BOD detector 22 when 5c flows, and 24 is set by the BOD detector 22. A comparing means 25 comprising a microprocessor or the like for comparing the detected value with the set value stored in the set value storage section 23, and a micro means 25 for judging the membrane replacement time from the result of comparison by the comparing means 24. It is a judgment means composed of a processor. Reference numeral 26 denotes a display unit such as a liquid crystal panel for notifying the user of the membrane replacement time when the membrane replacement time is determined by the determination unit 25. The display unit 26 constitutes a notification unit according to the first embodiment of the present invention. As the notification means, an alarm may be sounded using an alarm device. 27 is a flow rate switching means for adjusting the flow rate of the solution to be injected into the microbial electrode 1 based on the result of the judgment by the judgment means 25.

FIG. 2 shows a BOD according to an embodiment of the present invention.
FIG. 3 is a flowchart (1) of the sensing device, FIG. 3 is a flowchart (2) of the BOD sensing device according to an embodiment of the present invention, and FIG. 4 is a BO according to an embodiment of the present invention.
Flowchart (3) of the D sensing device, FIG. 5 is a flowchart (4) of the BOD sensing device according to an embodiment of the present invention, and FIG.
FIG. 7 is a flowchart (5) of the OD sensing device, FIG. 7 is a flowchart (6) of the BOD sensing device according to the embodiment of the present invention, and FIG. 8 is a flowchart (7) of the BOD sensing device according to the embodiment of the present invention. is there. Hereinafter, description will be made with reference to the flowcharts of FIGS. A timer for counting the date and time is built in the BOD sensing device. The built-in timer 18 always counts the date and time and the time. First,
Using the operation panel 17, a preset built-in time program is selected (step 1). When there is no sample water 6 for measurement and the measurement is not performed (step 2),
The judging means 25 judges that the currently set flow rate value should be changed to a non-measurement flow rate value, and the flow rate switching means 27 receiving the judgment adjusts the flow rate (step 3). The flow rate value at the time of non-measurement is smaller than the flow rate value at the time of measurement, and flows the minimum necessary flow rate. When the measurement is performed in the presence of the sample water 6, the mode switching means 20 switches the valve driving means 2 by the mode switching means 20 every time the introduction time set in the time program arrives.
1 is operated to switch the switching valve 2 so that the measuring cell 1
Introduce into 3. The buffer 4 is continuously introduced until the measurement becomes possible (step 4), and then the washing solution 3 is similarly introduced (step 5). This (step 4) (s
Step 5) may be repeated alternately (step 6).
As a result, when measurement becomes possible, a calibration curve is created (s
step7).

If the buffer solution 4 has been introduced into the solution introduction path, the cleaning solution 3 is introduced by the switching valve 2 after the preset buffer solution introduction time elapses, and until the preset washing time elapses. Alternatively, if the cleaning liquid 3 has been introduced, the apparatus waits until a preset cleaning time has elapsed (step 8), and then introduces the standard liquid 5a by the switching valve 2 into the preset standard liquid introduction time (s).
(Step 9) After detecting as a current value by the microbial electrode 1, detection is performed as a BOD value (step 10). The comparison unit 24 compares the BOD value at this time with the set value of the standard solution 5a stored in the set value storage unit 23 in advance (s
Step 11) If the measurement result is lower than the set value of the standard solution 5a stored in the set value storage unit 23 in advance, the determination unit 25 determines that the time for replacing the membrane has come, and gives the user a time to replace the membrane. Is notified (step 12). The standard solution 5 whose measurement result is stored in the set value storage unit 23 in advance.
If the value is equal to or larger than the set value a, the determination means 25 determines that there is no abnormality in the measured value, sets the measurement result of the standard solution 5a as a new calibration curve, rewrites the previous calibration curve, and updates the calibration curve (s
step13). Thereafter, the mode switching means 20 switches the switching valve 2 and introduces the cleaning liquid 3 into the measuring cell 13 until a predetermined cleaning time elapses (s
step14). Subsequently, the mode switching means 20 switches the switching valve 2 again to introduce the standard solution 5b into the preset standard solution introduction time measuring cell 13 (step 1).
5) After being detected as a current value by the microbial electrode 1,
It is detected as a BOD value (step 16). B at this time
The comparing unit 24 compares the OD value with the set value of the standard solution 5b stored in the set value storage unit 23 in advance (ste).
p17) If the measurement result is lower than the set value of the standard solution 5b stored in the standard storage unit 23 in advance, it is determined that the membrane replacement time has come, and the user is notified that the membrane replacement time has come. (Step 18). If the measurement result is equal to or larger than the preset value of the standard solution 5b stored in advance, the determination means 25 determines that there is no abnormality in the measurement value, and uses the measurement result of the standard solution 5b as a new calibration curve, and the previous calibration curve. Is updated to update the calibration curve (step 19).

Thereafter, the mode switching means 20 switches the switching valve 2 to introduce the cleaning liquid 3 until a preset cleaning time has elapsed (step 20). Thereafter, the standard solution 5c is introduced by the switching valve 2 for a predetermined standard solution introduction time set in advance (s).
(Step 21) After detecting as a current value by the microorganism electrode 1, it is detected as a BOD value (Step 22). The comparison unit 24 compares the BOD value at this time with the set value of the standard solution 5c stored in the set value storage unit 23 in advance (s
Step 23), standard solution 5c in which the measurement result is stored in advance
If the value is lower than the set value, the determination means 25 determines that the time for replacing the membrane has come, and notifies the user that the time for replacing the membrane has come (step 24). If the measurement result is equal to or greater than the set value of the standard solution 5c stored in the set value storage unit 23 in advance, the determination unit 25 determines that there is no abnormality in the measured value, and determines the measurement result of the standard solution 5c as a new calibration value. The calibration curve is updated by rewriting the previous calibration curve (step 2).
5).

The mode switching means 20 switches the switching valve 2 to introduce the cleaning liquid 3 into the measuring cell 13 until a preset cleaning time has elapsed (step 2).
6). When the determination means 25 determines that there is no abnormality in the measured value, the measurement result of the standard solution 5c is used as a new calibration curve, and the previous calibration curve is rewritten (step 27). When the above procedure is completed, the updating of the calibration curve is completed.

After completing the above, the measurement is started (step
p28). When the measurement is not performed, the procedure returns to (step 7), and the calibration curves of the standard solutions 5a, 5b, and 5c are updated according to the above procedure. When performing the measurement, the mode switching means 20 switches the switching valve 2 and introduces the sample water 6 into the measurement cell 13 until a predetermined injection time has elapsed (step 29). Thereafter, the switching valve 2 is switched by the operation of the mode switching means 20, and the measuring cell 13 is supplied with the cleaning liquid 3 until a predetermined cleaning time set in advance.
(Step 30). Thereafter, the switching valve 2 is switched, and the standard solution 5a is introduced into the measurement cell 13 for a preset standard solution introduction time (step 31), detected as a current value by the microorganism electrode 1, and then detected as a BOD value (step 32). . The BOD value at this time is compared with the set value of the standard solution 5a stored in the set value storage unit 23 in advance by the comparison unit 24 (step 33), and the measurement result is stored in the standard solution stored in the set storage unit 23 in advance. If it is lower than the set value of 5a, the comparing means 24 determines that it is time to replace the membrane, and notifies the user that the time to replace the membrane has come (step 34). If the measurement result is equal to or greater than the preset value of the standard solution 5a stored in advance, the determination means 25 determines that there is no abnormality in the measurement value, and uses the measurement result of the standard solution 5a as a new calibration curve, and the previous calibration curve Is updated to update the calibration curve (step 35). If the measurement is not continued thereafter, the procedure returns to (step 7) to create a calibration curve.

If the measurement is to be continued further (step
36), the mode switching means 20 switches the switching valve 2 and introduces the cleaning liquid 3 into the measurement cell 13 until a preset cleaning time has elapsed (step 37), and the mode switching means 20 switches the switching valve 2 to detect the sample. Water 6 is introduced into measurement cell 13 until a predetermined injection time has elapsed (step 38). Next, the cleaning liquid 3 is introduced into the measuring cell 13 by the switching valve 2 until a predetermined cleaning time has elapsed (step 39). After that, the switching valve 2 is switched to introduce the standard solution 5b for a predetermined standard solution introduction time (step 40), and the current value is detected by the microorganism electrode 1 and then detected as the BOD value (step 4).
1). The BOD value at this time is compared with the set value of the standard solution 5b stored in the set value storage unit 23 in advance (step 4).
2) If the measurement result is lower than the preset value of the standard solution 5b stored in advance, it is determined that the time for replacing the membrane has been reached, and the user is notified that the time for replacing the membrane has come (step 43). If the measurement result is equal to or greater than the preset value of the standard solution 5b stored in advance, the determination means 25 determines that there is no abnormality in the measurement value, sets the measurement result of the standard solution 5b as a new calibration curve, and The calibration curve is updated by rewriting (step 44). If the measurement is not continued thereafter, the process returns to (step 7) to create a calibration curve. To continue the measurement (step 4
5), the mode switching means 20 switches the switching valve 2, and introduces the cleaning liquid 3 into the measuring cell 13 until a predetermined cleaning time has elapsed (step 46). Next, the sample water 6 is introduced into the measuring cell 13 by the switching valve 2 until a predetermined injection time that has been set in advance (ste).
p47). Further, the switching liquid 2 allows the cleaning liquid 3
Measurement cell 1 until a preset cleaning time has elapsed.
3 (step 48). Thereafter, the standard solution 5c is introduced into the predetermined standard solution introduction time measuring cell 13 by the switching valve 2 (step 49), detected as a current value by the microorganism electrode 1, and then detected as a BOD value (st).
ep50). The BOD value at this time is compared with the preset value of the standard solution 5c stored in advance (step 51). If the measurement result is lower than the preset value of the standard solution 5c stored in the preset value storage unit 23 in advance, Then, the judgment means 25 judges that it is time to change the membrane, and notifies the user that the time to change the membrane has come (step 52). When the measurement result is equal to or greater than the preset value of the standard solution 5c stored in advance, the determination means 25 determines that there is no abnormality in the measurement value, and uses the measurement result of the standard solution 5c as a new calibration curve, and replaces the previous calibration curve with the previous calibration curve. The calibration curve is updated by rewriting (step 53). If you do not want to continue the measurement,
Returning to (Step 7), a calibration curve is created. If the measurement is to be continued (step 54), the mode switching means 20 switches the switching valve 2 and the cleaning liquid 3 is supplied to the measuring cell 13 until a preset cleaning time has elapsed.
(Step 55). Thus, the measurement is continued in the order of the sample water 6 and the standard solutions 5a, 5b, 5c.

As described above, in the BOD sensing apparatus according to the first embodiment, the judgment means 25 judges the state of the membrane each time the BOD value of the standard solution 5a, 5b, 5c is measured, and the time for replacing the membrane comes. When the determination is made, this is notified, and it is possible to prevent a determination error caused by performing the determination of the membrane replacement time based on intuition, experience, or the like. If the BOD value is not checked, it is not noticed that the time for replacing the membrane has passed, and the buffer 4 and the washing solution 3 are not continuously injected into such a membrane. Further, since the BOD value can be confirmed even when a period in which the measurement is not performed continues, the measurement can be performed immediately without a preparation period. Since the notification unit is the display unit 9, the display unit 9 can always display the BOD value and the indication of the time to exchange the membrane,
It is suitable for long-term measurement. Further, in the first embodiment of the present invention, since there are a plurality of types of the standard solutions 5a, 5b, and 5c, it is possible to perform a highly accurate determination when the determination unit determines the time to replace the membrane.

[0024]

As described above, according to the present invention, it is determined whether or not the membrane has reached the replacement time by the determining means, and this is notified at the time of the replacement of the membrane. This eliminates erroneous judgment and prevents the solution from being continuously supplied to the membrane whose replacement time has passed. Also, when the notification means is a display unit, the display can be performed continuously,
The display is always displayed even in the long-term measurement, and the membrane can be replaced when the user finds the display. In addition, since a plurality of types of the standard solutions are prepared and the determination unit makes the determination a plurality of times, it is possible to make a highly accurate determination regarding the timing of replacing the membrane.

[Brief description of the drawings]

FIG. 1 is a block diagram of a BOD sensing device according to an embodiment of the present invention.

FIG. 2 is a flowchart (1) of a BOD sensing device according to an embodiment of the present invention.

FIG. 3 is a flowchart (2) of the BOD sensing device according to the embodiment of the present invention;

FIG. 4 is a flowchart (3) of the BOD sensing device according to the embodiment of the present invention.

FIG. 5 is a flowchart (4) of the BOD sensing device according to the embodiment of the present invention;

FIG. 6 is a flowchart (5) of the BOD sensing device according to the embodiment of the present invention;

FIG. 7 is a flowchart (6) of the BOD sensing device according to the embodiment of the present invention;

FIG. 8 is a flowchart (7) of the BOD sensing device according to the embodiment of the present invention.

FIG. 9 is a schematic configuration diagram of a conventional BOD sensing device.

FIG. 10 is a detailed view of a BOD detection device of a conventional BOD sensing device.

FIG. 11 is a block diagram of a conventional BOD sensing device.

FIG. 12 is a flowchart of a conventional BOD sensing device (1).

FIG. 13 is a flowchart (2) of a conventional BOD sensing device.

FIG. 14 is a flowchart (3) of a conventional BOD sensing device.

[Explanation of symbols]

 Reference Signs List 1 Microbial electrode 2 Switching valve 3 Cleaning solution 4 Buffer solution 5a Standard solution 5b Standard solution 5c Standard solution 6 Sample water 7 Pump 8 Air pump 9 Display unit 10 Waste liquid tank 11 Diaphragm-type oxygen electrode 12 Microbial membrane 13 Measurement cell 14 Insertion port 15 Discharge Exit 16 hot water tank

Claims (3)

[Claims] 1. A BOD detecting device having a measurement cell into which a solution is introduced and a microbial membrane on which an oxygen electrode and microorganisms are fixed, and a buffer, a washing solution, a standard solution or a sample water which is connected to the measurement cell and is switched as the solution. A solution supply unit that can be supplied by a pressure sensor, a comparing unit that compares a detection value detected by the BOD detection device with a predetermined set value, and a time when the membrane is replaced when the detected value is lower than the set value. When the detection value is equal to or greater than the set value, the apparatus further includes a determination unit configured to determine that the membrane replacement time has not yet elapsed, and a notification unit configured to notify a user of an output from the determination unit when the membrane replacement time has come. A BOD sensing device comprising: 2. The BOD sensing device according to claim 1, wherein said notification means is display means for notifying a user that a replacement time has come. 3. The BO according to claim 1, wherein there are a plurality of types of said standard solution, and said judging means judges the time to replace the membrane by comparing each set value of said standard solution with said detected value.
D sensing device.