JPH063315A - Biochemical oxygen consumption meter with microbial electrode - Google Patents

Abstract

(57) [Summary] [Objective] In a BOD _S measuring instrument, it is possible to prevent a BOD _S value having low accuracy from being calculated due to deterioration of a microbial membrane when a calibration curve is created. [Configuration] A reference current value I is provided as an index for judging deterioration of the microbial membrane 7, and compared with the calibration current value i of the microbial electrode 1 for the BOD _S calibration solution 4, and when the calibration current value i is equal to the reference current value I , Or when it is smaller than the reference current value I, the microorganism exchange indicator 11 is activated.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a biochemical oxygen consumption measuring instrument using a microbial electrode (hereinafter referred to as BOD _S measuring instrument).
Regarding

[0002]

2. Description of the Related Art FIG. 2 shows the configuration of a conventional BOD _S measuring instrument.

The BOD _S measuring device is a microbial electrode 1 for detecting BOD _S in a sample water, a data processing device 5 for calculating the output current of the microbial electrode 1, a sample water 3 for the microbial electrode 1,
The BOD _S calibration solution 4 is composed of a liquid feed pump 2 which is switched and supplied. The microbial electrode 1 is composed of a microbial membrane 7 on which microorganisms are immobilized, an oxygen electrode 6, and a flow cell 8.

Consisting of glucose and L-glutamic acid,
The BOD _S calibration solution 4 having a known concentration is supplied to the microbial electrode 1 by the liquid feed pump 2, the calibration current value of the microbial electrode 1 is input to the data processing device 5, and a BOD _S calibration curve is created. Next, the liquid feed pump 2 is switched to the test water 3 and B of the test water 3
The output current value of the microbial electrode 1 that changes according to OD is input to the data processing device 5, and B is output according to the calibration curve created above.
Convert to OD _S.

[0005]

However, the microbial membrane 7 constituting the above-mentioned conventional BOD _S measuring instrument is gradually deteriorated according to the life of the immobilized microorganisms when used for a certain period.

FIG. 3 shows the change with time of the relative value of the calibration current of the microbial electrode 1 with respect to the BOD _S calibration solution 4 in the BOD _S measuring instrument manufactured according to JIS K 3602.

The calibrating current value of the microbial electrode 1 for the BOD _S calibrating solution 4 begins to drop around 30 days, and drops to about 50% at the start of the test in 50 days.

In the BOD _S measuring instrument, the microbial membrane 7 is deteriorated and
Even when the calibration current value for the OD _S calibration solution 4 is reduced and a normal value is no longer output, a calibration curve is created for that calibration current value, and B of the test water 4 based on the calibration curve is created.
Since the OD _S value is calculated, there is a drawback that the accuracy of the BOD _S value for the test water becomes low.

Therefore, the present invention makes it possible to prevent the calculation of a low-precision BOD _S value due to deterioration of the microbial membrane.

[0010]

A reference current value is stored in a data processing device as an index for determining deterioration of a microbial membrane, and the calibration current value of a microbial electrode for a BOD _S calibration solution is used as the reference current when a calibration curve is created. A microbial membrane exchange annunciator that is capable of externally detecting the exchange of microbial membranes is provided, which is activated when the calibration current value is equal to the reference current value or smaller than the reference current value.

[0011]

The BOD of the present invention having the above structure_SFor measuring instruments
In addition, BOD was created when the calibration curve was created. _SMicroorganism for calibration solution
When the calibration current value of the electrode becomes smaller than the reference current value,
Notification of microbial membrane exchange that allows external detection of microbial membrane exchange
The vessel starts and can be used as a guide to replace the microbial membrane
Therefore, BOD with low accuracy_SPrevents calculating the value
You can

[0012]

1 (A) and 1 (B) show an example of a BOD _S measuring device of the present invention.

The preparation of the calibration curve with the BOD _S calibration solution 4 and the measurement of the test water 3 are the same as in the conventional method.

As an index for judging the deterioration of the microbial membrane 7,
A reference current value I is provided and stored in the data processing device 10.
The reference current value I is, for example, 0.8 of the calibration current relative value in FIG.
Set the value corresponding to.

Next, at the time of preparing the calibration curve, the BOD whose concentration is known is
The calibration current value i of the microbial electrode 1 for the _S calibration solution 4 is input to the data processing device 10. The data processor 10 compares the reference current value I with the calibration current value i of the microbial electrode 1 for the BOD _S calibration solution 4.

Whether the calibration current value i is equal to the reference current value I,
If it is smaller than the reference current value I, the microbial membrane exchange alarm 11 is activated to notify the outside of the device that the microbial membrane 7 has been exchanged.

The microbial membrane exchange indicator 11 may be one whose activation can be confirmed from the outside of the device, such as a lamp, a buzzer, or a liquid crystal.

[0018]

According to the present invention described above, when the calibration current value of the microbial electrode for the BOD _S calibration solution becomes smaller than the reference current value at the time of creating the calibration curve, the microbial membrane exchange indicator capable of detecting the exchange of the microbial membrane from the outside. Is activated and can be used as a guide to replace the microbial membrane, so the accuracy is low.
It is possible to prevent the _S value from being calculated.

[Brief description of drawings]

FIG. 1A is a diagram showing an example of a BOD _S measuring device of the present invention. (B) is a diagram showing an operation of the data processing device of the BOD _S measuring device of the present invention.

FIG. 2 is a diagram showing an example of a conventional BOD _S measuring device.

FIG. 3 is a diagram showing a change with time of a relative value of a calibration current of a microbial electrode with respect to a BOD _S calibration solution.

[Explanation of symbols]

1 Microbial Electrode 3 Water Detection 4 BOD _S Calibration Solution 10 Data Processing Device 11 Microbial Membrane Exchange Alarm i Calibration Current Value I Reference Current Value

Claims (1)

[Claims] 1. A reference current value is stored in a data processor as an index for determining deterioration of a microbial membrane, and the calibration current value of the microbial electrode for the BOD _S calibration solution and the reference current value are stored when a calibration curve is created. In comparison, when the calibration current value is equal to the reference current value, or when the calibration current value is smaller than the reference current value, activated, a microbial membrane exchange indicator that can detect the exchange of microbial membranes from the outside is provided, biochemistry by a microbial electrode Oxygen consumption meter.