JPS59222753A - Measuring apparatus using microorganism electrode - Google Patents

Abstract

PURPOSE:To enable measurement for a long time by washing a microorganism electrode with a washing liquid which is prepared at pH of 2-5 while a substance blocking the growth of bacteria, none of leaven is added thereto. CONSTITUTION:A microorganism electrode 2 is made up of a diaphragm type oxygen electrode 3 and a microorganism membrane 4. Then, a buffer liquid B such as phosphoric acid buffer liquid is fed to a measuring cell 5 with a pump 9 while a washing liquid N thereto 5 through a changeover valve 13 and the pump 9. Here, the washing liquid N is prepared at pH 2-5 by adding hydrochroric acid slightly to a tap water and also, a substance blocking growth of bacteria none of leavens. Then, the changeover valve 13 is switched over to feed a sample liquid S such as factory liquor through a sampling pump 10 and a filter 18 in place of the washing liquid N and BOD of the sample liquid S is measured with the microorganism electrode 2. When a specified time is reached, the changeover valve 13 is switched over to feed standard liquids C1, C2 and C3 for calibration.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a measuring device for measuring acetic acid, ammonia substances, BOD, etc. in a solution using a microbial electrode formed by combining a diaphragm-type oxygen electrode and a microbial membrane using yeast.

Conventional using microbial electrodes? 1! Examples of I-determining devices include, for example, JP-A-54-47699 and JP-A-56-108.
There is an apparatus disclosed in No. 951.

However, when such a device as described above is used for a long period of time, a phenomenon is observed in which the output from the microbial electrode decreases, which may prevent normal measurement.

In view of the above circumstances, the inventors of this invention conducted intensive research and found that oil, suspended substances, etc. in the sample liquid adhered to the flow path piping and the surface of the microbial membrane, and that biological slime was found in the flow path. It was found that one of the causes of the above phenomenon is that oxygen is generated on the pipes and membrane surfaces, reducing the concentration of the substance to be measured in the flow path and blocking the flow of oxygen to the oxygen electrode. .

This invention was made based on the above findings, and
The object of the present invention is to provide a measuring device that can suppress the occurrence of the above phenomenon by being equipped with means for preventing biological slime and the like from adhering to the flow path piping and the surface of the microbial membrane.

That is, the present invention has a microbial electrode formed by combining a diaphragm-type oxygen electrode and a microbial membrane using yeast, a liquid inlet and a liquid outlet, and a liquid flowing between them so that the liquid can come into contact with the microbial membrane. a measuring cell placed relative to the microbial electrode;
A buffer solution supply means for supplying a buffer solution to the measurement cell, a measurement liquid supply means for supplying a measurement liquid to the measurement cell, an air supply means for supplying air to the measurement cell, and a cleaning liquid to the measurement tank. It is equipped with a cleaning liquid supply means,
A measuring device using a microorganism electrode is provided, in which the cleaning liquid is adjusted to pH 2 to 5 and added with a bacterial growth inhibitory substance that does not inhibit the growth of yeast.

Examples of the above-mentioned bacterial growth inhibitor include antibiotics such as chloramphenicol, penicillin, neomycin, aureomycin, and streptomycin.

A more detailed explanation will be given below based on the embodiment shown in the figures.

(1) shown in Figure 1 is a BOD continuous measuring device.
This is an example of a measuring device using the microbial electrode of the present invention.

(2) is a microbial electrode, which has a known configuration consisting of a combination of a diaphragm-type oxygen electrode (3) and a microbial membrane (4).

A measuring cell (5) is attached to the lower part of the microbial electrode (2), and the liquid that flows in from the liquid inlet (5a) of the measuring cell (5) and flows out to the liquid outlet (5b) forms a microbial membrane (4). It has come to be in contact with The liquid inlet (5a) is located at a different level below the liquid outlet (5b) so that the liquid can effectively contact the microbial membrane (4).

These microbial electrode (2) and measurement cell (5) are maintained at a predetermined temperature (for example, 30° C.) in a constant temperature water bath (6). (7) is a coil-shaped flow path whose length is determined so that the liquid reaches approximately a predetermined temperature while passing through the flow path.

(8) is a control circuit such as a microcomputer, and according to a preset procedure, the buffer solution (S), sample solution (S),
8? i Pump (9) + 10 to supply semi-liquids (C□) to (C3), cleaning liquid □□□ and air to the measurement cell (5)
1. Control the air pump θ and switching valve θ. Further, the BOD value is calculated based on the output current of the microbial electrode (2).

Cleaning solution (2) is made by adding a slight amount of hydrochloric acid to tap water to adjust the pH to about 8, and adding an antibiotic.

Next, to explain the operation, first, phosphate buffer (o, oiM
, pH 7) is added to the roller pump (9).
) is supplied to the measuring cell (5) via the switching valve (13) and the roller pump (9), and cleaning liquid (1) is supplied to the measuring cell (5) via the switching valve (13) and the roller pump (9). Also, a constant air pump (
Air is supplied from +2). The flow rate of the buffer solution 03) is, for example, 0.8 mt'/min, and the flow rate of the washing solution □ is, for example, 1
．． 2-7 minutes, the air flow rate is, for example, 800 m11 minutes.

At this time, the output current of the microbial electrode (2) provides a baseline value.

At the time of sample measurement, the switching valve (1st floor) is switched and a sample liquid (S) such as factory wastewater is supplied via the collection pump (10) and the filter θ~ instead of the cleaning liquid.

Supply of buffer solution, etc. is the same as before. Microbial electrode (
The output current of 2) shows a decreasing value proportional to the BOD of the sample solution (S).

As mentioned above, the sample liquid (S) is supplied to the measurement cell (5) for about 5 minutes every 30 minutes, and the cleaning liquid N is supplied at other times.

At the predetermined calibration setting time, the switching valve θ is switched and the standard solution (C1), (C8,
), (C3) are respectively supplied to the measurement cell (5),
Measurements are taken for each. Each standard solution (C1),
Since the BOD values of (C2) and (C3) are known,
Based on the output values of the microbial electrode (2) for these, the control circuit (8) calibrates the calibration curve. For example, this calibration is 1
It is held several times a day.

Example FIG. 2 shows a BOD value of 50 to 100/7! using a device similar to the device of the above example (+). FIG. 2 is a diagram showing changes in the baseline value of the output current of the microbial electrode by continuously repeating measurements of wastewater from a cafeteria at 30-minute intervals (sample measurement time: 5 minutes/cleaning liquid supply time: 25 minutes). (a) shows the case where tap water with a pH of about 7 is used as the cleaning liquid, and there is a remarkable phenomenon in which the baseline value decreases as the number of measurements increases. (b
) is a case where tap water adjusted to pH 8 by adding hydrochloric acid was used as the cleaning liquid, and the decrease in the baseline value was smaller than in (a). (C) is a case where tap water prepared by adding hydrochloric acid to adjust the pH to about 8 and to which io omg7i of chloramphenicol was added was used as a cleaning liquid, and a decrease in the baseline value was considerably prevented.

Example In an apparatus similar to the above-mentioned Example apparatus (1), a standard solution of glucose and glutamic acid with a BOD value of 200 my/l was supplied for 15 minutes and a cleaning solution was supplied for 30 minutes, which was repeated for 10 days. coil(
7) Piping (vinyl tube, length 2m,
The ``degree'' of the inner diameter (1 am) was investigated. The "degree" is calculated using the following formula.

In other words, degree - ([amount of water flowing through the piping before the experiment] - [amount of water flowing through the piping after the experiment]) / [amount of water flowing through the piping before the experiment] When tap water with a pH of about 7 is used as the cleaning liquid, the "clogged degree" was 38%, indicating that a considerable amount of biological slime was attached to the inner surface of the pipe.

When tap water adjusted to pH 4 by adding hydrochloric acid was used as a cleaning solution, the "clogging rate" was 19%, and there was still a lot of biological slime attached.

When tap water was adjusted to pH 4 by adding hydrochloric acid and 80 my/l of chloramphenicol was used as a cleaning solution, the 1 degree was 10%, and the adhesion of biological slime was considerably prevented. Ta.

As understood from the above explanation, the microorganism W of this invention
According to the measurement device using the L8ii, the piping and the surface of the microbial membrane are cleaned with a cleaning solution that is acidic and contains substances that inhibit the growth of bacteria, thereby preventing contamination of the piping and the microbial membrane due to adhesion of biological slime, etc. , it becomes possible to continue measurements suitably over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of a BOD continuous measuring device which is an embodiment of the present invention, and FIG. 2 is a diagram showing an example of a change in baseline value over time in a device similar to the device shown in FIG. 1. (1)...BOD continuous measurement device,

Claims (1)

[Claims] 1. A microbial electrode formed by combining a diaphragm-type oxygen WL electrode and a microbial membrane using yeast, which has a liquid inlet and a liquid outlet, and the liquid flowing between them is in contact with the microbial membrane. A measurement cell arranged with respect to the microbial electrode so as to be moist, a buffer supply means for supplying a buffer solution to the measurement cell, a measurement liquid supply means for supplying a measurement liquid to the measurement cell, and an air supply to the measurement cell. and a cleaning liquid supplying means for supplying a cleaning liquid to the measurement tank, the cleaning liquid having a pH of
1. A measuring device using a microbial electrode, characterized in that it is prepared as follows: 2 to 5 and contains a bacterial growth inhibiting substance that does not inhibit the growth of yeast. 2. Bacterial growth inhibitors include chloramphenicolte,
2. The apparatus according to claim 1, wherein the cleaning solution is added at a concentration of 80TR41/l to 100Q/13.