JP2001165926A - Coulometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a coulometer by integrating an electrolytic cell with a manometer. SOLUTION: Carbon dioxide is increased accompanying the reduction of oxygen in a culture cell 1, caused by the respiration of aerobic microorganisms and this formed carbon dioxide is adsorbed by a carbon dioxide adsorbent 12 to lower the pressure in the culture cell 1. Since the culture cell 1 is connected to an electrolytic cell 14 by an air pipe 13, the surface of the liquid in the air pipe 13 rises, and a current flows across electrodes 14a, 14b and a relay switch is turned on by a relay circuit 16, and a constant current flows across electrodes 14a, 14c. As result, a copper sulfate aqueous solution D is electrolyzed due to the flow of the constant current across both electrodes, and oxygen is generated from the electrode 14a to be supplied to the culture cell 1. The amount of oxygen generated can be calculated, on the basis of the quantity of the current flowing across the electrodes 14a, 14c, and the amount of oxygen consumed by aerobic microorganisms in the sample A within the culture cell 1 can be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coulometer for measuring biochemical oxygen demand, which is the amount of oxygen consumed by the respiration and growth of aerobic microorganisms.

[0002]

2. Description of the Related Art A coulometer (BOD measuring device) is used for, for example, BOD measurement of sewage wastewater and the like, and a purification simulator. Further, it is used in a wide range of fields such as microbiological engineering, pharmacy, medicine, fisheries science, agriculture, and chemical engineering, such as measurement of the degree of decomposition of chemical substances by microorganisms and the effect of drugs on microorganisms.

FIG. 2 is a schematic view of a detecting unit in the coulometer. The detecting unit is provided in a constant temperature bath for maintaining a constant temperature, and a measuring unit and a measurement result are recorded outside the constant temperature bath. Recording unit is connected. At the bottom of the culture cell 1 in the detection section, a sample A containing aerobic microorganisms is provided.
The culture cell 1 is further provided with a carbon dioxide adsorbent 2 and an electrolysis cell 3 for generating oxygen by performing constant-current electrolysis of the aqueous copper sulfate solution B therein. The culture cell 1 is connected via a vent pipe 5 to a manometer 4 filled with water C having conductivity.

[0004] The carbon dioxide in the culture cell 1 increases as the oxygen partial pressure in the culture cell 1 decreases due to the respiratory action of the aerobic microorganisms. Adsorbed, the pressure in the culture cell 1 decreases. Further, since the culture cell 1 is connected to the manometer 4 by the ventilation pipe 5, the liquid level of the water C in the ventilation pipe 5 rises.

[0005] Due to the rise of the liquid level in the ventilation pipe 5, water C
The electrode 6a provided therein and the electrode 6b provided in the ventilation pipe 5 are electrically connected by water C, and a current flows through the relay circuit 6. As a result, a relay switch (not shown) is turned on, and a current flows between the positive electrode 3a and the negative electrode 3b provided in the electrolytic cell 3, and the copper sulfate aqueous solution B in the electrolytic cell 3 is subjected to constant current electrolysis. Generates oxygen. Culture cell 1
As the oxygen is supplied into the cell, the pressure in the culture cell 1 rises again and the liquid level in the ventilation tube 5 drops, so that the relay switch is turned off, the constant current electrolysis stops, and the supply of oxygen stops. .

By repeating the above steps and measuring the current flowing between the electrodes 3a and 3b using the constant current meter 7, the amount of oxygen generated from the electrolytic cell 3 can be calculated. The amount of oxygen consumed by the aerobic microorganism can be measured.

[0007] As shown in FIG. 3, the electrolysis cell 3 is arranged outside the culture cell 1,
A device for supplying oxygen to a gas is also known.

[0008]

However, in the conventional coulometer shown in FIG. 2, since the culture cell 1 and the electrolytic cell 1 are integrated, when the sample A is frequently changed, the handling becomes complicated.

Further, in the coulometer shown in FIG. 3, although the exchange of the sample A is easy, the number of joints for joining the culture cell 1 and the electrolytic cell 3 increases, which causes gas leakage, and furthermore, There is a problem that the size of the whole system becomes large.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a small-sized coulometer that allows easy exchange of a sample and has few joints.

[0011]

A coulometer according to the present invention for attaining the above object comprises connecting a culture cell and an electrolytic cell via a vent pipe, and connecting a sample containing aerobic microorganisms in the culture cell. A carbon dioxide adsorbent is placed, the electrolytic cell is filled with an electrolytic solution that generates oxygen by constant current electrolysis, the tip of the vent tube is inserted into the electrolytic solution, and a positive electrode is inserted into the electrolytic cell inside the vent tube. The negative electrode is disposed in the electrolytic solution outside the vent pipe, and a liquid level sensor provided in the vent pipe detects a rise in the level of the electrolytic solution, and the positive electrode is disposed in the positive electrode. And a circuit for flowing a current between the negative electrode and the current, the positive and negative electrodes electrolyze the electrolytic solution, and oxygen generated from the positive electrode is supplied to the culture cell through the ventilation tube. It is characterized by doing.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiment shown in FIG. FIG. 1 is a schematic diagram of a detecting unit in the coulometer in the present embodiment, and the entire detecting unit is provided in a constant temperature bath in order to keep the temperature constant. The bottom of the culture cell 11 is filled with a sample A containing aerobic microorganisms, and a carbon dioxide adsorbent 12 for adsorbing carbon dioxide is arranged above the sample A. The culture cell 11 is connected to an electrolytic cell 14 filled with an aqueous solution of copper sulfate D via a ventilation tube 13. In the aqueous solution D of the electrolytic cell 14 and in the vent pipe 5, the first positive electrode
, A second electrode 14b is provided above the liquid level in the ventilation tube 5, and a third electrode 14c as a negative electrode is provided in the aqueous solution D in the electrolytic cell 14.

The first electrode 14a is connected to a relay circuit 16 via a constant current meter 15, and the second electrode 14b,
The third electrode 14c is also connected to the relay circuit 16.
The relay circuit 16 is connected to the first and second electrodes 14.
a, 14b conduct, the first and third electrodes 1
It is configured to allow a current to flow between 4a and 14c.

At the time of the test, the dissolved oxygen in the sample A decreases due to the respiration of the aerobic microorganisms in the sample A in the culture cell 11. When this dissolved oxygen decreases, the culture cell 1
1 is supplied with oxygen. And culture cell 1
As the amount of oxygen in 1 decreases, carbon dioxide increases, and the generated carbon dioxide is adsorbed by the carbon dioxide adsorbent 12, so that the pressure in the culture cell 11 decreases by the volume of consumed oxygen. .

Further, since the culture cell 11 is connected to the electrolysis cell 14 through the ventilation pipe 13, the electrolysis cell 14
The liquid level inside the ventilation pipe 13 rises. As a result, the first and second electrodes 14a and 14b conduct through the aqueous solution of copper sulfate D, function as a liquid level sensor, and a current flows between the first and second electrodes 14a and 14b to cause a relay circuit. Fifteen
Operates. Then, when a not-shown relay switch in the relay circuit 15 is turned on, a constant current flows between the first and third electrodes 14a and 14c by the constant current meter 15, and the copper sulfate aqueous solution D is subjected to constant current electrolysis. Electrolytic oxygen is generated from the first electrode 14a of the positive electrode, supplied to the culture cell 11 through the ventilation tube 13, and copper is deposited on the third electrode 14c of the negative electrode. By the supply of oxygen, the liquid level in the ventilation pipe 13 also drops as the pressure in the culture cell 11 returns to normal, and when the conduction between the electrodes 14a and 14b is cut off, the relay switch is turned off, and the copper sulfate aqueous solution D is fixed. Current electrolysis stops.

By repeating the above steps, the amount of electricity consumed can be easily measured as the product of the current value and the electrolysis time by the constant current meter 15 between the first and third electrodes 14a and 14c. The amount of generated oxygen can be calculated from the amount of electricity, and the amount of oxygen consumed by the aerobic microorganisms in the sample A can be measured.

Also, by using a recorder, it is possible to monitor how oxygen is consumed by aerobic microorganisms.

In this embodiment, an aqueous solution of copper sulfate D is used as the electrolytic solution in the electrolytic cell. However, any other electrolytic solution may be used as long as oxygen is generated as a gas during constant current electrolysis. Is also good.

In this embodiment, the first and second electrodes 14a and 14b are used as the liquid level sensors for detecting the liquid level of the electrolytic solution, but the second and third electrodes 14b and 14c are used. You may. Furthermore, there is no problem even if a liquid level sensor such as a reed switch is separately applied without using these electrodes.

[0020]

As described above, in the coulometer according to the present invention, by integrating the electrolytic cell and the manometer, it is possible to reduce the size of the entire system, and further reduce the number of joints to reduce the amount of gas. Leakage can be reduced, and measurement accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a detection unit of a coulometer in the present embodiment.

FIG. 2 is a schematic diagram of a detection unit of a conventional coulometer.

FIG. 3 is a schematic diagram of a detection unit of a conventional coulometer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Culture cell 12 Carbon dioxide adsorbent 13 Vent tube 14 Electrolysis cell 14a 1st electrode 14b 2nd electrode 14c 3rd electrode 15 Constant ammeter 16 Relay circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4B029 AA07 BB01 BB02 BB15 BB20 CC01 FA15 4D061 DA10 DB09 EA03 EB37 EB38 EB39 EB40 FA15 FA20 GA04 GB23 GB30 GC12

Claims (4)

[Claims] 1. A culture cell and an electrolysis cell are connected via a vent pipe, a sample containing aerobic microorganisms and a carbon dioxide adsorbent are arranged in the culture cell, and oxygen is supplied to the electrolysis cell by constant current electrolysis. Fill the electrolytic solution to be generated, insert the tip of the vent tube into the electrolytic solution, place a positive electrode in the electrolytic solution of the electrolytic cell inside the vent tube, and place the negative electrode outside the vent tube. It is arranged in the electrolyte, detects a rise in the liquid level of the electrolyte by a liquid level sensor provided in the ventilation pipe, and constitutes a circuit for flowing a current between the positive electrode and the negative electrode. A coulometer, wherein the electrolytic solution is electrolyzed by positive and negative electrodes, and oxygen generated from the positive electrode is supplied to the culture cell through the ventilation tube. 2. The coulometer according to claim 1, wherein the amount of oxygen consumed by the sample is measured by converting the current for the electrolysis into an amount of electricity using a constant ammeter to calculate the amount of oxygen generated. . 3. The coulometer according to claim 1, wherein the current is a constant current. 4. The liquid level sensor according to claim 1, wherein the liquid level sensor has a mechanism for detecting conduction by the electrolytic solution between an electrode disposed above a liquid level in the ventilation pipe and the positive or negative electrode. Coulometer.