JPH10170478A - Bod-measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a BOD(biochemical oxygen demand)-measuring apparatus which requires only a little amount of solution for measurements and is compact and easy to carry with. SOLUTION: The BOD-measuring apparatus is provided with a microbe electrode part 42, a storing part 50 and an oxygen feed means for supplying oxygen to the vicinity of the microbe electrode part 42. The microbe electrode part 42 has a cathode electrode for reducing a dissolved oxygen in a solution to be measured, an anode electrode for emitting electrons, an oxygen gas-passing film covering the cathode electrode, and a microbe film immobilized on the oxygen gas-passing film for utilizing organic components in the solution to be measured. The microbe electrode part 42 is inserted into the storing part 50 where the solution to be measured can be stored. An air vent part 52 is set above the storing part 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a BOD (Biochemical Oxygen Demand) measurement for measuring the degree of pollution of sewage water, sewage, and wastewater of laundry, vehicle washing facilities, food manufacturing, restaurants and the like. It concerns the device.

[0002]

2. Description of the Related Art Conventionally, measurement of BOD (Biochemical Oxygen Demand) has been carried out according to the official method (industrial wastewater test method JIS K0102) defined in Japanese Industrial Standards. This method leaves the wastewater at 20 ° C for 5 days,
It measures the amount of decrease in dissolved oxygen and is a measurement method called BOD5. However, this conventional official method BOD
In the case of No. 5, a long time of 5 days was required for the measurement, and it was necessary to store the waste water being measured until the measurement result was understood. In addition, BOD5 had to be measured by measuring COD (chemical oxygen consumption) in order to determine the amount of seed bacteria to be charged, which was very troublesome and troublesome. The measurement by BOD5 should make the oxygen consumption for 5 days 40-70% of the saturated dissolved oxygen amount. Therefore, if the oxygen consumption for the last 5 days deviates from 40 to 70% of the saturated dissolved oxygen amount, it must be measured again, in which case another 5 days are required, and a very long time is required for the measurement. Required.

[0003] Therefore, as a simple measuring method not based on BOD5, an apparatus for measuring BOD using a microbial electrode has been proposed (JP-B-57-54742, JP-B-58-30537, JP-B-61-7258). 6-37324). These are those which measure BOD using a microbial electrode using yeast, and can be measured simply and quickly. This conventional BOD measuring device will be described below. This BOD measuring device is a flow cell that is capable of flowing a neutral buffer solution into a flow cell equipped with a microbial electrode to maintain neutral conditions and blowing air into the flow cell corresponding to the BOD component in the liquid under measurement under air-saturated conditions. It is a device that takes out the amount of dissolved oxygen decrease, that is, the amount of dissolved oxygen consumed by metabolism of microorganisms (yeast), as an output of a diaphragm oxygen electrode, and detects and measures this. Further, a microcomputer or a sequence controller that controls the BOD measuring device so that the BOD can be automatically measured is known.

[0004] In such a BOD measuring apparatus, the BOD value of the test water is based on the output when a cleaning liquid (water or water containing a slime preventing liquid) is supplied as a liquid to be measured, and on the other hand, Calibration of the output voltage-BOD value concentration conversion is performed from the output voltage when one or more standard solutions composed of organic component-containing solutions with known BODs are supplied, and then the test water is supplied and measured. Have been done.

[0005] The supply of the cleaning liquid, the standard liquid and the test water is performed by a liquid supply means for switching and introducing any of the cleaning liquid, the standard liquid and the test water into the liquid introduction path to the flow cell. The liquid supply means is usually constituted by a pump for guiding a cleaning liquid, a standard liquid, or a sample to the flow cell, and a solenoid valve for switching.

[0006]

However, a conventional BOD measuring device using a microbial electrode using a yeast is:
In the flow method of measuring while introducing a washing solution, a standard solution or a test solution into the flow cell, the test solution is supplied to the microbial electrode while flowing alternately with the phosphate buffer as a test solution,
It required a large amount of solution (the solution to be measured and the phosphate buffer). In addition, the flow method requires a micro tube pump and a piping tube, and there is a problem that it is very difficult to reduce the size and portability.

Therefore, the present invention solves such a conventional problem, and can be measured with a small amount of solution.
It is an object of the present invention to provide a small and easily portable BOD measurement device.

[0008]

In order to achieve the above object, a BOD measuring apparatus according to the present invention comprises: a storage section into which a microorganism electrode section is inserted and in which a liquid to be measured can be retained; Oxygen supply means for supplying oxygen to the vicinity of the microbial electrode unit to saturate oxygen; and the storage unit is provided with an air vent at the top.

Thus, it is possible to provide a small-sized and easily portable BOD measuring device that can measure with a small amount of solution.

[0010]

DETAILED DESCRIPTION OF THE INVENTION According to the first aspect of the present invention, there is provided a cathode electrode for reducing dissolved oxygen in a liquid to be measured,
A microorganism comprising an anode electrode for emitting electrons, an oxygen gas permeable film covering the cathode electrode, and a microorganism film immobilized on the oxygen gas permeable film and assimilating organic components in the liquid to be measured. An electrode section, a storage section into which the microorganism electrode section is inserted and capable of retaining the liquid to be measured, and an oxygen supply for supplying oxygen near the microorganism electrode section to saturate oxygen in the liquid to be measured. The BOD measuring apparatus is characterized in that the storage section is provided with an air vent section on the upper portion, so that the measurement can be carried out with a small amount of solution retained.

According to a second aspect of the present invention, there is provided a first cathode electrode and a second cathode electrode for reducing dissolved oxygen in a liquid to be measured, and a first anode electrode and a second anode for emitting electrons. An electrode, a first oxygen gas permeable membrane covering the first cathode electrode, and a second oxygen gas permeable membrane covering the second cathode electrode.
A microbial electrode section comprising an oxygen gas permeable membrane, a microbial membrane immobilized on the first oxygen gas permeable membrane and assimilating organic components in the liquid to be measured, and the microbial electrode section is inserted. A reservoir capable of retaining the liquid to be measured, and oxygen supply means for supplying oxygen to the vicinity of the microbial electrode to saturate oxygen in the liquid to be measured, wherein the reservoir has an air vent at the top. B characterized by having a portion provided
Since it is an OD measuring device, the amount of dissolved oxygen consumed in proportion to the organic components in the liquid to be measured is measured at the first cathode electrode provided with the microbial membrane, and the amount of oxygen in a saturated state is measured at the second cathode electrode. The BOD can be measured in a short time by comparing the two without the need for a liquid sending time because there is no piping tube or the like for liquid sending.

According to the third aspect of the present invention, since the oxygen supply means is an air pump, the storage section can be set to the condition of oxygen saturation, and the dissolved oxygen consumed by the metabolism of microorganisms The quantity can be taken as the output of the oxygen electrode.

According to the fourth aspect of the present invention, since the oxygen supply means is a solid oxygen generating agent, it can be easily miniaturized and carried.

(Embodiment 1) A BOD measuring apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic block diagram of an electric circuit of a BOD measuring device according to an embodiment of the present invention. FIG. 2 is a schematic overall view of a BOD measuring device according to an embodiment of the present invention. FIG. 4 is a cross-sectional view of the microbial electrode portion of the double-sided electrode pattern in which part A of FIG. 2 is partially enlarged. FIG. 5 is a plan view of the microbial electrode portion of the double-sided electrode pattern in which part A of FIG. 2 is a cross-sectional view of a single-sided electrode pattern of a microbial electrode portion in which part A of FIG. 2 is partially enlarged. FIG. 7 is a plan view of a microbial electrode portion of a single-sided electrode pattern in which part A of FIG. 2 is partially enlarged.

Referring to FIG. 2, B in the first embodiment will be described.
The OD measuring device will be described. BO of Embodiment 1
D measuring device is equipped with air pump, 41 is BOD
The measuring device main body 42 is a microorganism electrode unit. The microorganism electrode section 42 will be described later. 43 is a microorganism electrode part 4
An air nozzle 44 provided near the microbial electrode 2 and supplying air to the microbial electrode unit 42 is a liquid crystal display unit that displays the BOD measurement value measured by the microbial electrode unit 42. 45 is an air pump for sending air to the air nozzle 43, 47 is a power switch button, 48 is a measurement start button, and 49 is a calibration button. The air pump 45 sends air to the standard liquid or the liquid to be measured, and saturates the dissolved oxygen amount between the standard liquid and the liquid to be measured. Of course, oxygen may be supplied in addition to air. In the first embodiment, the oxygen supply means includes an air pump 45 and an air nozzle 43. Reference numeral 50 denotes a storage unit that can retain the liquid to be measured or the standard solution measured by the microorganism electrode unit 42.
Reference numeral 1 denotes a measuring instrument holding unit, and 52 denotes an air vent provided on the storage unit 50. In the first embodiment, the air vent 5
Although a hole is formed as 2, an air vent valve may be provided. The measuring device holder 51 is not always necessary, and may be a stationary type. The storage unit 50 performs calibration and measurement of the internal liquid. Air vent 52
Is provided in the storage unit 50, so that when air is mixed into the liquid to be measured or the standard solution from the air nozzle 43, the excess air accumulated in the storage unit 50 without being dissolved in the liquid flows out. In addition, it is possible to prevent excess air from interfering with the BOD measurement. As described above, in the first embodiment, the air pump 4 serving as an oxygen supply unit is
5 and the air nozzle 43, and the air vent 5
2 is provided, so that the flow type BOD measuring device, which had to constantly flow the liquid to be measured, is replaced with a batch type BOD measuring device.
It can be a D measuring device.

Next, the details of the microorganism electrode section 42 will be described. 4 to 7, reference numeral 72 denotes an oxygen gas permeable film made of Teflon, resist, or the like. Dissolved oxygen can be reduced on the surface in contact with the liquid to be measured. Since the reduction current flows to the electrode 76 through the oxygen gas permeable membrane 42, the oxygen gas permeable membrane 42 can be regarded as apparently permeable to oxygen, and is referred to as a permeable membrane here. 73 is a resin mold, 74
Is a microbial membrane on which microorganisms such as yeast (trichosporoncutaneum) are fixed, and 75 is an electrolyte such as KCl. The electrode 76 is an anode electrode 11 made of a metal such as aluminum.
And a cathode electrode 10 for reducing dissolved oxygen. Reference numeral 77 denotes a liquid to be measured, which is a liquid to be measured or a standard liquid to be introduced into the storage unit 50. Reference numeral 78 denotes a through hole in the case of the double-sided electrode shown in FIGS. 4 and 5 as described later. In the first embodiment, in order to increase the current density, the periphery around the cathode electrode 10 is the anode electrode 11.
Are configured so as to surround in a C shape. The oxygen gas permeable membrane 72 has one surface in contact with the liquid to be measured and the other surface in contact with the electrolytic solution 75. A reduction reaction occurs on the surface in contact with the liquid to be measured, and dissolved oxygen is hydroxylated. It is changed into ions. On the other hand, in the anode electrode 11, the electrode is oxidized and eluted, and excess electrons are emitted. As a result, a weak current flows between the anode electrode 11 and the cathode electrode 10 and is output.

The electrolytic solution 75 is filled in the holes of the perforated plate adhered on the substrate of the microbial electrode section 42, and the upper portion is covered with an oxygen gas permeable membrane 72. This oxygen gas permeable film 72 is fixed to a perforated plate by a resin mold 73. An electrode pattern made of aluminum or the like is baked on the substrate of the microorganism electrode section 42. 4 and 5 show the case where the electrode 76 of the microorganism electrode section 42 uses a double-sided electrode pattern, and FIGS. 6 and 7 show the case where the electrode 76 of the microorganism electrode section 42 uses a single-sided electrode pattern. It shows. That is, in FIGS. 4 and 5, electrode patterns are formed on both sides of the perforated plate, and
The microbial electrode portion 42 shown in FIGS. 6 and 7 has an electrode pattern formed only on the substrate side. When the microbial electrode portion 42 having a double-sided electrode pattern formed thereon is used as the microbial electrode portion 42, the oxygen gas permeable membrane 72 and the cathode 10
Is directly connected, and a more accurate value can be measured than when the microorganism electrode portion 42 has a single-sided electrode pattern.

The microbial electrode section 42 is provided with two sets of the anode electrode 11 and the cathode electrode 10. The first anode electrode 11 and the first cathode electrode 10 provided below the storage unit 50 are provided with a microbial membrane 74 that further covers the first oxygen gas permeable membrane 72 that covers the first anode electrode 11 and the first cathode electrode 10. But the second
No microbial membrane 74 is provided on the anode electrode 11 and the second cathode electrode 10. Therefore, if an organic component is present in the liquid to be measured, the first cathode electrode 10 having the microbial membrane 74 assimilates the organic component by metabolism of a microorganism such as yeast (trichosporoncutaneum),
At this time, the dissolved oxygen is consumed and the remaining dissolved oxygen is reduced by the cathode electrode 10. However, in the second cathode electrode 10 without the microbial membrane 74, the dissolved oxygen in the saturated state is reduced as it is. Is output. Since two sets of the anode electrode 11 and the cathode electrode 10 are provided and only one of them is provided with the microbial membrane 74, the oxygen saturation state and the oxygen consumption state consuming oxygen proportional to the organic component can be simultaneously measured. The measurement of the reference value can be performed at the same time, and since there is no piping tube for liquid supply, no liquid supply time is required, and the measurement time can be extremely short, about 10 minutes. Since the microbial membrane 74 is provided at a position below the storage unit 50, air exceeding a required amount is buoyant to the storage unit 50.
And is discharged from the air vent 52 to the outside.

Subsequently, the BO of the first embodiment will be described with reference to FIG.
The electric circuit of the D measuring device will be described. In FIG. 1, reference numeral 1 denotes a microcomputer, and 2 denotes a power switch for switching the microcomputer 1 from a hold mode to an operation mode. Reference numerals 3 and 4 denote measurement start switches and calibration switches, 5 to 7 and 9 denote pull-up resistors, and 8 denotes a power supply voltage monitoring IC. Reference numerals 13 and 83 denote current-voltage conversion amplifiers, which convert current into voltage by resistors 14 and 84, respectively. 15, 85 are capacitors, 1
6 and 86 are resistors, and 17 and 87 are zener diodes. Capacitors 15 and 85 are current-voltage conversion amplifiers 1
3, 83 are added to prevent oscillation. The reference voltages of the current-voltage conversion amplifiers 13 and 83 are provided by zener diodes 17 and 87. Therefore, the output voltage from the current-to-voltage conversion amplifiers 13 and 83 is smaller than the reference voltage given by the zener diodes 17 and 87 by the minute electrode current from the cathode electrodes 10 and 80. Of the current-voltage conversion circuit of FIG.
4, 84 to which the voltage obtained by current-voltage conversion is applied, and this potential is input to analog input ports P4, P5 of the microcomputer 1 described below. The microcomputer 1 calculates the potentials input to the analog input ports P4 and P5, and outputs the output ports P11 to P11.
By controlling P29, the measured BOD value is displayed on the liquid crystal 18. 19 is an oscillation circuit. However, the oscillation circuit 19 may be oscillated by incorporating oscillation software in the microcomputer 1. In this case, the output of the "H" level and the output of the "L" level are alternately output at a constant cycle to the output port P30 of the microcomputer 1 described below, so that a buzzer is generated. Reference numeral 20 denotes a voltage generation circuit, and reference numeral 21 denotes a negative voltage generation circuit. 22, a matching resistor; and 23, a buzzer. This negative voltage generating circuit 21 generates a negative potential by a charge pump method by combining a capacitor and a diode. This is because the electric circuit of the first embodiment is driven by a battery, so that a sufficient voltage cannot be supplied and the sound pressure of the buzzer 23 cannot be secured, and is added to obtain this voltage. If the sound pressure of the buzzer 23 is not required, it may be grounded to the GND level. Further, a transistor having a common collector for switching may be used. The voltage generation circuit 20 is a switching transistor for turning on / off the buzzer 23 in the first embodiment. The matching resistor 22 is for matching the impedance of the buzzer 23.

Ports P4 and P5 of the microcomputer 1 are ports for analog input and have an A / D converter built-in. Reference numeral 30 denotes a battery, 31 denotes a three-terminal regulator, 32 denotes a transistor, 33 denotes a resistor, and 34 denotes a power supply for supplying logic, which supplies, for example, + 5V. Reference numeral 35 denotes a transistor output voltage for controlling power supply at the output port P10. In the first embodiment, about +4.
7V is applied. The HOLD port is an input port for releasing the hold mode for switching the microcomputer 1 from the hold mode to the operation mode. P
Reference numerals 1 and 2 denote a measurement start switch input and a calibration switch input port, respectively. P3 is an input port for monitoring the power supply voltage, P9 is an output port for driving the air pump 45, 79 is a pump driver composed of a transistor or an IC for driving the air pump 45, P11
P19, P21 to P29 are liquid crystal display output ports for liquid crystal display, and P30 is a buzzer output port.

Next, B is measured using the BOD measuring apparatus of the present invention.
The procedure and operation for measuring the OD will be described. As shown in FIGS. 2 and 3, a standard solution having a known BOD value is introduced into the storage unit 50, and the microbial electrode unit 42 of the part A at the tip of the BOD measuring device main body 41 is immersed in the standard solution. The microorganism electrode section 42 is fixed to the measuring instrument holding section 51. Next, when the power switch button 47 shown in FIG. 2 is pressed, the power switch 2 shown in FIG. 1 is turned on, and the microcomputer 1 is switched from the hold mode to the operation mode by a signal from the HOLD port input of the microcomputer 1. And the microcomputer 1 becomes operable.

Next, when the calibration button 49 is pressed, the calibration switch 4 shown in FIG. 1 is turned on, and the port P2 of the microcomputer 1 changes from "H" level to "L" level, and the air The pump 45 is driven, and air is sent from the air nozzle 3 into the storage unit 50.
This saturates the dissolved oxygen in the standard solution,
After the measurement for one minute, the calibration is terminated by the timer built in the microcomputer 1, and the buzzer is sounded. Upon completion of the calibration, the port P2 returns from the "L" level to the "H" level again.

After the calibration is completed, the liquid to be measured, which is the liquid 77 to be measured, is introduced into the storage unit 10. Start measurement button 8
When the measurement start switch 3 shown in FIG. 1 is turned on, the port P1 of the microcomputer 1 is turned on.
From the “H” level to the “L” level. The driving of the air pump 45 is started, and air is sent from the air nozzle 3 into the storage unit 50, whereby the dissolved oxygen in the liquid to be measured is saturated. After the measurement for 10 minutes, the output port P30 of the microcomputer 1 is changed from the “H” level to the “L” level.
'Complete the measurement by leveling the buzzer.

In the above calibration and measurement, B
A weak electrode current flows between the cathode electrode 10 and the anode electrode 11 and between the cathode electrode and the anode electrode 81 of the oxygen electrode of the OD sensor. The minute electrode current from the cathode electrodes 10 and 80 is reduced by the resistors 14 and 84 of the current-voltage conversion circuit using the current-voltage conversion amplifiers 13 and 83.
The voltage is converted, and a potential is generated as an output of the current-voltage conversion amplifiers 13 and 83. This potential is input to the analog input ports P4 and P5 of the microcomputer 1. The microcomputer 1 calculates the voltage potentials of the analog input ports P4 and P5 and outputs the output ports P11 to P29.
To display the measured BOD value on the liquid crystal 18.

When measuring another sample of the liquid to be measured, after the first sample is measured, the microbial electrode section 42 is removed from the measuring instrument holding section 51 and replaced with a new activated microbial electrode section 42. And attach it. Reservoir 5 again
Calibration is completed after 10 minutes have elapsed after the standard solution has been introduced into 0. Next, after measuring the liquid to be measured for 10 minutes, the measurement is completed, and the measurement result (measured value) is displayed on the liquid crystal display unit 4.

As described above, the BOD measuring apparatus according to the first embodiment differs from the flow type BOD measuring apparatus in which the liquid to be measured must be constantly flowed, and uses only a small amount of the liquid to be measured and the standard liquid. It can be a batch type BOD measuring device that can measure. And since the air vent part 52 is provided in the storage part 50, when air is mixed into the liquid to be measured or the standard liquid, the air is prevented from dissolving in the liquid and remaining in the storage part 50 to prevent the BOD measurement. be able to.

Further, since two sets of anode electrode 11 and cathode electrode 10 are provided and only one of them is provided with the microbial membrane 74, the oxygen saturation state and the oxygen consumption state consuming oxygen proportional to the organic component can be measured simultaneously. Measurement time is 1
This can be performed in a very short time of about 0 minutes.

When it is desired to use the microbial electrode 42,
Can be easily measured by directly attaching it to the measuring device body, it can be measured if microorganisms have enough time to assimilate organic components in wastewater, and the microbial electrode section 42 is disposable. Since there is no need for regeneration time, the BOD of the liquid to be measured can be measured in a short time.
Also, unlike the flow method, a cleaning liquid is not required, and the amount of the electrolytic solution 75 in the microbial electrode section 42 may be very small.

(Embodiment 2) FIG. 3 is a schematic overall view of a BOD measuring apparatus according to another embodiment of the present invention. In the second embodiment, the oxygen supply means for supplying oxygen into the storage unit 50 uses a chemical. What has been described in the first embodiment is common to all except for the air pump 45 and the air nozzle 43, and a detailed description thereof will be omitted in the first embodiment. In the second embodiment, a solid oxygen generator that generates oxygen is used as a drug as an oxygen supply unit. The solid oxygen generating agent is charged into the storage unit 50, and the liquid to be measured and the standard solution are introduced into the storage unit 50 in this state. When this solid oxygen generating agent is immersed in the liquid to be measured or the standard liquid, it reacts with water to generate oxygen and dissolves in these liquids. Solid oxygen generators include calcium peroxide, sodium percarbonate and catalase.
If the amount of the solid oxygen generating agent is determined according to the volume of the storage unit 50, the amount of oxygen accumulated above the storage unit 50 after saturation can be reduced.

According to the second embodiment, there is no need to provide an air pump 45 or an air nozzle 43 for supplying air or oxygen, and the size of the apparatus can be further reduced. Also, the microcomputer 1 controls the air pump 45.
, And a very simple batch-type BOD measuring device can be provided.

[0031]

According to the present invention, measurement can be performed with a small amount of solution, and since the air vent portion is provided in the storage portion, when air or oxygen is mixed with the liquid to be measured or the standard solution, Even if it becomes excessive because it does not dissolve into the BOD, it is possible to prevent the BOD measurement from being accumulated in the storage chamber and hindering the BOD measurement, and it is possible to provide a small-sized, easy-to-carry batch-type BOD measurement device.

Further, since two sets of anode and cathode electrodes are provided in the microbial electrode part and only one of them is provided with a microbial membrane, the oxygen saturation state and the oxygen consumption state in proportion to the organic components due to the metabolism of the microorganism are simultaneously measured. Therefore, the measurement time can be extremely short. The measurement can be easily performed simply by introducing the measuring solution into the storage part.The measurement is possible if the microorganisms have enough time to assimilate the organic components in the wastewater. The BOD of the liquid to be measured can be measured in a short time because regeneration time is not required.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an electric circuit of a BOD measuring device according to an embodiment of the present invention.

FIG. 2 is a schematic overall view of a BOD measuring device according to an embodiment of the present invention.

FIG. 3 is a schematic overall view of a BOD measuring device according to another embodiment of the present invention.

FIG. 4 is a cross-sectional view of a microbial electrode part having a double-sided electrode pattern in which part A of FIG. 2 is partially enlarged;

FIG. 5 is a plan view of a microbial electrode portion having a double-sided electrode pattern in which a portion A of FIG. 2 is partially enlarged;

FIG. 6 is a cross-sectional view of a microbial electrode portion having a single-sided electrode pattern in which a portion A of FIG. 2 is partially enlarged;

FIG. 7 is a plan view of a microbial electrode portion having a single-sided electrode pattern in which a portion A of FIG. 2 is partially enlarged;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microcomputer 2 Power switch 3 Measurement start switch 4 Calibration switch 5, 6, 7, 9 Pull-up resistor 8 Power supply voltage monitoring IC 10, 80 Cathode electrode 11, 81 Anode electrode 13, 83 Current-voltage conversion amplifier 14, 16, 33, 84, 86 Resistance 15, 85 Capacitor 17, 87 Zener diode 18 Liquid crystal 19 Oscillation circuit 20 Voltage generation circuit 21 Negative voltage generation circuit 22 Matching resistance 23 Buzzer 30 Battery 31 3-terminal regulator 32 Transistor 34 Power supply 35 Transistor output voltage 41 BOD measuring device main body 42 Microbial electrode unit 43 Air nozzle 44 Liquid crystal display unit 45 Air pump 47 Power switch button 48 Measurement start button 49 Calibration button 50 Storage unit 51 Measuring device holding unit 52 Air vent unit 72 Oxygen gas Permeable membrane 73 resin mold 74 microbial film 75 electrolytic solution 76 electrode 77 the liquid to be measured 78 through hole 79 pump drivers

Continued on the front page (72) Inventor Kazuyoshi Mori 1006 Kazuma Kadoma, Kazuma, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] A cathode electrode for reducing dissolved oxygen in a liquid to be measured, an anode electrode for emitting electrons,
A microbial electrode section comprising an oxygen gas permeable membrane covering the cathode electrode, a microbial membrane immobilized on the oxygen gas permeable membrane and assimilating organic components in the liquid to be measured, and the microbial electrode section is inserted. A storage part capable of retaining the liquid to be measured as well as oxygen supply means for supplying oxygen to the vicinity of the microbial electrode in order to saturate oxygen in the liquid to be measured, wherein the storage part has A BOD measuring device, wherein an air vent portion is provided at an upper portion. 2. A first cathode electrode and a second cathode electrode for reducing dissolved oxygen in a liquid to be measured, a first anode electrode and a second anode electrode for emitting electrons, and the first cathode electrode. A first oxygen gas permeable membrane covering the
A microbial electrode unit comprising: a second oxygen gas permeable membrane covering the cathode electrode; and a microbial membrane immobilized on the first oxygen gas permeable membrane and assimilating organic components in the liquid to be measured. A storage portion into which the portion is inserted and capable of retaining the liquid to be measured, and oxygen supply means for supplying oxygen to the vicinity of the microbial electrode portion to saturate oxygen in the liquid to be measured. A BOD measuring device, characterized in that an air vent is provided on the upper part of the part. 3. The BOD measuring device according to claim 1, wherein the oxygen supply means is an air pump. 4. The BOD measuring device according to claim 1, wherein the oxygen supply means is a solid oxygen generating agent.