JPH06258284A - Bod measuring device - Google Patents

Abstract

PURPOSE:To provide a highly accurate BOD measuring device which is excellent in relativity with an official regulation method by arranging a reaction container to perform decomposition treatment by oxygen reaction or catalytic reaction of semiconductor photocatalyst. CONSTITUTION:A constant quantity of sample water is introduced to a reaction tank 37 by a water sampling pump, and oxygen from an oxygen supply device 38 is sent to the tank 37 whose temperature is controlled by a temperature control device 39, and is agitated and reacted by an agitator 40, and a suspension material is made dissoluble, and is transformed into a low molecular weight together with a dissolved organic substance. After being kept at an oxygen-activated temperature for a constant time by a device 39, treated water of the tank 37 is sent to a BOD measuring device through a valve 11, and is measured. As another method, the sample water is introduced to a reaction container, and is agitated by the agitator together with semiconductor photocatalyst, and light is radiated from inside the reaction container by using a light source to emit light having an absorptive wave length of the semiconductor photocatalyst, and while supplying the oxygen by an air pump, the suspension material is oxidized and decomposed, and is made dissoluble, and is sent to a measuring device after the photocatalyst is removed, and is measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is a device for measuring BOD in wastewater from sewage treatment plants, factories, offices, etc., and in water in environmental waters such as rivers and lakes. The present invention relates to a well-measurable BOD measuring device.

[0002]

BOD is the dissolved oxygen content in water consumed by aerobic microorganisms at 20 ° C. for 5 days, expressed in mg / l, and is extremely important as the most representative water pollution index. BOD is usually Japanese Industrial Standard (JIS)
Factory drainage test method specified in JIS (JIS K 0102)
According to the official method, the official method requires (i) a long time of 5 days until the measurement result is obtained, and the measurement result is measured when managing the process such as wastewater treatment. I can't make the most of it quickly.

(B) For example, determination of the dilution ratio of the sample, p
H removal and interference removal operations, nitrification suppression,
Measurement operations such as planting are very complicated and require skill. (C) Since it is a manual analysis, automatic measurement cannot be performed. In recent years, the BOD measurement method using a biosensor (microorganism sensor) that applies an immobilized microbial membrane has been
It is described in Japanese Examined Patent Publication No. 61-7258.

The above-mentioned BOD measuring method using a biosensor is an effective BOD measuring method capable of measuring BOD in wastewater in about 20 to 40 minutes, and its apparatus was introduced in 1990 in Japan. Industrial standard (JIS K 3602: Biochemical oxygen consumption "BOD ₅ " measuring instrument by microbial electrode)
Came to be adopted as. However, since the pores of the immobilized microbial membrane are usually as small as 0.22 to 0.45 μm, the immobilized microorganisms should directly utilize the soluble organic substances that pass through the pores. However, suspended organic substances that cannot pass through the pores cannot be assimilated. In addition, the suspended organic matter causes clogging in the liquid delivery system (pump), the piping system (tube), etc. of the BOD measurement device, which is a serious problem in terms of measurement accuracy and maintenance. Further, this type of biosensor used for BOD measurement changes the pH value inside the immobilized microbial membrane due to the organic acid generated when the soluble organic matter in the sample water is assimilated, and the sensor output fluctuates. Therefore, in order to prevent this, a buffer solution is used, and the sample solution is mixed with the buffer solution and diluted before the measurement. Therefore, when continuously monitoring the BOD in the sample water, the consumption of the buffer solution increases, which causes problems in maintenance and running cost of the measuring device.

On the other hand, the present inventors solubilized suspended substances in sample water with a pretreatment device, and B derived from a suspending organic substance, which was impossible with the conventional biosensor methods.
A practical BOD measuring device that can measure the OD measuring device and saves the buffer solution is provided by the same applicant as Japanese Patent Application No. 3-2.
No. 05324 is pending. The outline is described below.

FIG. 4 is a BOD filed by the inventors of the present invention.
It is a schematic diagram which showed the flow direction of the sample water with the arrow about the structure of a measuring device. In FIG. 4, the water sampling device 1 includes a raw water pump 1a for sampling waste water, a sample water storage tank 1b sampled by overflow, and pipes. The pretreatment device 2 crushes suspended substances in a sample water sampled by the water sampling pump 3 and solubilizes them, and is configured using an ozonizer. The measuring device is the above water sampling device.
1 , a pretreatment device 2 , a biosensor 5 provided in a constant temperature bath 4, a standard solution bath 6, a dilution water bath 7, valves 8, 9, 1
0, 11, a liquid sending device including a pump 12 and a pipe, a buffer solution circulating device 15 including a buffer solution tank 13, a pump 14 and a pipe, a calculation process of an output signal of the biosensor 5 , and an operation of the measurement device. It is composed of an arithmetic / control circuit 16 for controlling the. As a buffer solution, 0.05 to 0.1 M, p
A phosphate buffer solution of H7.0 is used. The standard solution is a mixed solution of glucose and glutamic acid in the same amount, and is used for preparing the calibration curve of the biosensor 5 . Dilution water is BOD 0m
It is a standard solution of g / l and is used each time for measurement in order to wash the piping line and dilute the sample water.

FIG. 5 is a schematic sectional view showing the structure of the biosensor 5 . Hereinafter, description will be given by using both FIGS. 4 and 5 together. In FIG. 5, a biosensor 5 includes a flow cell 18 having an immobilized microbial membrane 17, and a dissolved oxygen detector 1
9 and can be stored in the constant temperature bath 4 shown in FIG. 4 to maintain the measured temperature. The sample water and the buffer solution are also kept at the measurement temperature by passing through the heat exchangers 20 and 21 inside the constant temperature bath 4. Biosensor
5, the immobilized microorganism in the immobilized microbial film 17, soluble organic substances outputs a reduced amount of dissolved oxygen consumed when it is assimilated by the dissolved oxygen detector 19 as a current value signal . This decrease amount of dissolved oxygen is proportional to the concentration of the soluble organic matter dissolved in the sample water, and therefore is calculated by the calculation / control circuit 16 from the output signal current value to obtain the soluble BO.
The value of D can be obtained.

The BOD measurement by the biosensor 5 is carried out for the current value of the output signal when a preset time of about 5 to 15 minutes has passed since the sample water was supplied into the flow cell 18. The output signal from the biosensor 5 is digitized by the A / D converter 22 of the calculation / control circuit 16 and sent to the calculation device 23, and the calibration curve formula and the BOD value of the sample water are calculated according to a predetermined calculation formula. And record. The calculated BOD value is output from the output device 24, or the valve 8 is output in accordance with a preset order and time.
Switching of 9, 10, and 11 and output of operation control signals for the water sampling pump 3 and the pretreatment device 2 . Buffer solution, as showed in the biosensor 5 in FIG. 5, flows out from the buffer solution flows from the inlet 27 buffer solution outlet 28, always 4~6ml
/ Min, the solution is transferred by the buffer solution circulation device 15 , passes through the heat exchanger 21, and is circulated while being maintained at the measurement temperature. The buffer solution contains 0.05 to 0.1 M, pH 7.
It is also possible to use a phosphate buffer solution of 0 and to which micronutrients are added.

First, in accordance with the switching command of the output device 24, only the dilution water in the dilution water tank 7 passes through the valve 10 and the heat exchanger 20 by the pump 12 to be kept at the measurement temperature and flow from the liquid inlet 29. Then, it is sent into the biosensor 5 and discharged from the liquid outlet 30 to the outside of the system. Biosensor 5
After the output signal of is stabilized, the valves 8 and 9.10 are sequentially switched according to a preset order, a calibration curve is created by the BOD standard solution, and the BOD calculation formula is stored in the memory 25. Next, at the time of calibration of the biosensor 5 , the sample water sampled at the same time by the water sampling pump 3 and solubilized by the pretreatment device 2 passes through the heat exchanger 20 by the pump 12 through the valve 11 and the measured temperature. And the BOD value is measured by being sent to the biosensor 5 . The biosensor 5 is calibrated several times a day, and the BOD measurement of the sample water can be repeated at regular time intervals.

FIG. 6 is a schematic diagram showing the structure of the pretreatment apparatus 2 in FIG. In FIG. 6, the pretreatment device 2 surrounded by a dotted line introduces a sample water sampled by the water sampling pump 3 into the reaction tube 31, and the concentrated oxygen from the oxygen concentrator 32 is ozonized by the ozonizer 33. And reaction tube 3
It is sent to 1 and made to react with sample water to make the suspended matter soluble and to have a low molecular weight together with dissolved organic matter. The sample water treated in the reaction tube 31 is temporarily stored in the reservoir 35 through the valve 34, the excess ozone is purged using the air pump 36, and the sample water is stored in the valve 11
(Same as FIG. 4). The suspended substance is solubilized by reacting with ozone, and the soluble organic substance can chemically break the high molecular weight bond to reduce the molecular weight.

As described above, the BOD measuring device described in Japanese Patent Application No. 3-205324, which is filed by the present inventors, has a solubilization treatment of a suspended substance in sample water by ozone oxidation, and at the same time, a BOD measuring device By decomposing dissolved organic matter into low molecular weight organic matter and changing it to a property that biosensor microorganisms can easily assimilate, BOD derived from suspended organic matter is measured, and dissolved high molecular weight organic matter is also measured. It has good correlation with and is highly practical.

[0012]

According to recent research,
Even if it is a soluble organic substance, in the case of a substance having a large molecular weight, the measured value by the biosensor becomes a lower value compared with the BOD value of JIS K 0102 (Factory wastewater test method) which is an official method, and for example, According to JIS, starch is BOD ₅
The value measured by the biosensor is 2.9 mg / l, while the value is 73.4 mg / l. The 22nd Lecture Meeting on Water Pollution, published by Japan Society for Water Pollution Research, p. 75
-76 (March 1988), "Wide characteristics of BOD sensor" by Watanabe et al. In addition, the biosensor was established in September 1990 as a biochemical oxygen consumption measuring device using a microbial electrode in JIS K3602, but the Water Pollution Control Act measures both suspended organic substances and soluble organic substances. It is necessary, and it is not permitted to manage the water quality specified by the Water Pollution Control Act by measurement with a biosensor.

Under these circumstances, the above-mentioned Japanese Patent Application No. 3-205 filed by the present inventors using a biosensor.
The BOD measuring device described in the specification of No. 324 has many advantages because it is equipped with a oxidative decomposition of a suspending organic substance and a pretreatment device for reducing a soluble organic substance having a high molecular weight. However, according to the subsequent research conducted by the present inventors, the same effect can be obtained by using a method of enzymatic decomposition and photolysis by a semiconductor photocatalyst instead of using an ozonizer in a pretreatment device for treating a suspended substance. It was clarified that the method of treating suspended solids was appropriately applied to the measurement sample, and the high molecular weight BOD of the suspending organic matter was also determined to be a low molecular weight and correlated with the BOD measurement value of the official method. It has been found that it is possible to perform BOD measurement with high accuracy and high accuracy.

The present invention has been made in view of the above-mentioned points, and an object thereof is a BOD derived from a suspending organic substance and a high molecular weight BOD derived from a soluble organic substance as a low molecular weight. An object of the present invention is to provide a highly accurate BOD measurement device that has good correlation with the BOD measurement value.

[0015]

In order to solve the above-mentioned problems, the BOD measuring device of the present invention is the BOD described in the specification of Japanese Patent Application No. 3-205324 filed by the present inventors. In place of the ozone oxidation device used in the pretreatment device of the measuring device, a reaction tank for decomposing the sample water by enzymatic reaction or a reaction container for decomposing by catalytic reaction of semiconductor photocatalyst is provided in the system. It is a thing.

That is, the BOD measuring device of the present invention comprises a water sampling device for sampling and storing sample water, a pretreatment device for introducing sample water and oxidatively decomposing the sample water by using an enzyme or a semiconductor photocatalyst, and a standard solution. ， Delivery device that sends diluted water to the dissolved oxygen detector of immobilized microbial membrane of biosensor, buffer solution circulation device that circulates buffer solution to dissolved oxygen detector, arithmetic processing of biosensor output signal and main measurement And a calculation / control circuit for controlling the operation of the apparatus.

[0017]

Since the BOD measuring device of the present invention is configured as described above, suspended substances in the sample water such as wastewater that has passed through the pretreatment device are crushed by an enzymatic decomposition reaction or a semiconductor photocatalytic catalytic reaction. Solubilization and crushing and solubilization to decompose suspended organic matter derived from suspended solids and dissolved organic matter of high molecular weight, and change the property of the microorganisms in the immobilized microbial membrane to assimilate In addition to BOD derived from organic substances, high molecular weight substances among soluble organic substances can be measured, which has a good correlation with the BOD measurement value of the official method and has high measurement accuracy.

[0018]

EXAMPLES The present invention will be described below based on examples. The basic configuration of the BOD measuring device according to the present invention is the same as that shown in FIG. 5, and the only difference is the pre-processing device, and therefore the description of the entire BOD measuring device is omitted here.
Only the pretreatment device will be illustrated and described.

FIG. 1 is a schematic diagram showing the structure of the main part of a pretreatment device used in the BOD measuring device of the present invention, in the case where an enzymatic reaction is used instead of the decomposition reaction by the ozonizer. In FIG. 1, the pretreatment apparatus 2a surrounded by a dotted line introduces a sample water sampled in a fixed amount into a reaction tank 37 by a water sampling pump 3 (common to FIG. 5) (not shown), and from the enzyme supply device 38. The supplied enzyme is sent to the reaction tank 37 whose temperature is controlled by the temperature control device 39, and the enzyme is reacted with the sample water while being stirred by the stirrer 40 to make the suspended substance soluble and to dissolve the dissolved organic matter. And low molecular weight. The sample water treated in the reaction tank 37 is kept at a temperature at which the enzyme is deactivated by the temperature control device 39 for a certain period of time, and then the BO is passed through the valve 11 (common to FIG. 5).
D can be sent to the measuring device to perform the measurement.

FIG. 2 is also a schematic view showing the main structure of the pretreatment device used in the BOD measuring device of the present invention, in which a semiconductor photocatalyst is used instead of the decomposition reaction by the ozonizer. In FIG. 2, the pretreatment device 2 surrounded by a dotted line
In b , a sample water sampled in a fixed amount is introduced into the reaction container 41 by a water sampling pump 3 (not shown) (common to FIG. 5),
With the semiconductor photocatalyst supplied from the semiconductor photocatalyst supply device 42, light is irradiated from the inside of the reaction vessel 41 by using a light source 45 which is agitated by an agitator 43 and emits light having an absorption wavelength of the semiconductor photocatalyst cooled by a light source cooler 44. The
While the oxygen is supplied from the air diffuser 47 by the air pump 46, the suspended matter in the sample water is oxidatively decomposed to make it soluble, thereby reducing the molecular weight together with the dissolved organic matter. The sample water treated in the reaction vessel 41 is filtered through the filter 48 to remove the suspended semiconductor photocatalyst, and then the valve 1
1 (common to FIG. 5) through a BO not shown here.
D can be sent to the measuring device to perform the measurement. Thick arrows indicate the circulation direction of the cooling water 49, and 50 is a lighting device attached to the light source 45.

FIG. 3 shows the use of the BOD measuring device of the present invention.
It is a bar chart which shows the measurement result obtained about sewage secondary treated water. The characteristic bars in FIG. 3 are shown separately for the official method BOD, the BOD measuring device, and the DOC.
Is a BOD based on the official method based on JIS K 0102.
The measured value, the BOD measuring device is the BOD measured value when the device of the present invention is used, and the DOC is the dissolved organic carbon concentration (mg-C
/ L). 3, the pretreatment device
By 2a or 2b , the concentration of dissolved organic matter in the sample water pretreated for the enzymatic decomposition reaction or semiconductor photocatalytic reaction is increased as compared with the case where it is not treated, and the BOD measurement value by the official method is almost unchanged. When the pretreatment is not carried out, the output of the biosensor is small and only about 63% of the value measured by the official method can be obtained. However, 30% of sample water is obtained by using the pretreatment device 2a or 2b according to the present invention. The output of the biosensor (BOD measurement value) is increased by performing the partial reaction, and 80% of the official measurement value is obtained by the enzyme reaction, and about 87% of the official measurement value is obtained by the semiconductor photocatalyst reaction. I was able to. As described above, the rate of increase of the measured value by the BOD measuring device of the present invention cannot be explained by the increase of DOC, and not only the quantitative change but also the lowering of the molecular weight of the soluble organic substance and the substance easily assimilated by microorganisms Change to
It shows that qualitative changes are also proceeding at the same time.

[0022]

[Effects of the Invention] B in water in wastewater from sewage treatment plants, factories, business establishments, and in environmental waters such as rivers and lakes.
When OD is measured by a BOD measuring device using a biosensor, it is necessary to solubilize suspended organic matter in sample water and further reduce high molecular weight soluble organic matter to a low molecular weight. In the invention, as described in the embodiments, Japanese Patent Application No. 3-20532 filed by the present inventors.
In addition to the oxidation treatment by ozone such as the BOD measurement device described in the specification of No. 4, a pretreatment device utilizing decomposition treatment by enzymatic reaction or decomposition treatment by catalytic reaction of semiconductor photocatalyst is used to construct a suspension system. BO derived from turbid organic matter
Along with the measurement of D, the high molecular weight organic matter in the dissolved state, which had been measured by the biosensor so far lower than the BOD measurement value by the official method, was also measured as a value close to the measured value by the official method and correlated with the official method. And improved measurement accuracy
It is possible to obtain a highly practical BOD measurement device.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of a pretreatment device using an enzyme in a BOD measuring device of the present invention.

FIG. 2 is a schematic diagram showing the configuration of a pretreatment device using a semiconductor photocatalyst in the BOD measurement device of the present invention.

FIG. 3 is a bar chart showing the measurement results of the BOD measurement device of the present invention in comparison with other measurement methods.

FIG. 4 is a schematic diagram showing the configuration of a BOD measuring device that the present inventors have applied for.

FIG. 5 is a schematic diagram showing the configuration of a pretreatment device used in the BOD measurement device that the present inventors have applied for.

FIG. 6 is a schematic diagram showing the configuration of a biosensor used in the BOD measurement device that the present inventors have applied for.

[Explanation of Codes] 1 water sampling device 1a raw water pump 1b storage tank 2 pretreatment device 2a pretreatment device 2b pretreatment device 3 water sampling pump 4 thermostatic bath 5 biosensor 6 standard solution tank 7 dilution water tank 8 valve 9 valve 10 valve 11 valve 12 pump 13 buffer solution tank 14 pump 15 buffer solution circulation device 16 arithmetic / control circuit 17 immobilized microbial membrane 18 flow cell 19 dissolved oxygen detector 20 heat exchanger 21 heat exchanger 22 A / D converter 23 arithmetic device 24 Output device 25 Memory 27 Buffer solution inlet 28 Buffer solution outlet 29 Liquid inlet 30 Liquid outlet 31 Reaction tube 32 Oxygen concentrator 33 Ozonizer 34 Valve 35 Reservoir 36 Air pump 37 Reaction tank 38 Enzyme supply device 39 Temperature controller 40 Stirrer 41 Reaction vessel 41 42 Semiconductor Photocatalyst Supply Device 43 Stirrer 44 Light Cooler 45 light source 46 pump 47 aeration tube 48 filter 49 cooling water 50 lighting device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location G01N 33/18 105 7055-2J 7363-2J G01N 27/46 ZAB (72) Inventor Kenro Ueno Kanagawa 1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki-shi Fuji Electric Co., Ltd.

Claims (4)

[Claims] 1. A biosensor combining an immobilized microbial membrane carrying microorganisms that biochemically decompose organic matter in sample water and a dissolved oxygen detector for measuring the amount of dissolved oxygen in the sample water. Biochemical oxygen demand)
A device for measuring water, a water sampling device that collects and stores sample water, a pretreatment device that introduces sample water and oxidizes and decomposes the sample water, and dissolves reagents, wash water, and sample water. Equipped with a liquid sending device to send to the oxygen detector, a buffer solution circulating device to circulate the buffer solution to the dissolved oxygen detector, and a calculation / control circuit for calculating the output signal of the biosensor and controlling the operation of the measurement device. A BOD measuring device characterized in that 2. The BOD measuring device according to claim 1,
The pretreatment device has an enzyme supply device for decomposing suspended matter in the sample water introduced into the reaction tank by an enzymatic reaction, a temperature control device for controlling the temperature of the reaction tank, and a stirrer for stirring the sample water. A BOD measuring device characterized in that 3. A BOD in a sample water by a biosensor in which an immobilized microbial membrane holding microorganisms that biochemically decompose organic matter in the sample water and a dissolved oxygen detector for measuring the dissolved oxygen amount in the sample water are combined. Biochemical oxygen demand)
Which is a device for measuring and collecting sample water, a pretreatment device for introducing sample water and performing oxidative decomposition of the sample water using a semiconductor photocatalyst, a reagent, washing water, and sample water. A solution sending device for sending to the dissolved oxygen detector, a buffer solution circulating device for circulating a buffer solution in the dissolved oxygen detector, and a calculation / control circuit for calculating the output signal of the biosensor and controlling the operation of the measurement device. A BOD measuring device characterized by being provided. 4. The BOD measuring device according to claim 3,
The pretreatment device is a semiconductor photocatalyst supply device for decomposing suspended matter in the sample water introduced into the reaction vessel by a catalytic reaction,
A light source for irradiating the semiconductor photocatalyst with light in the reaction vessel, an air pump for blowing oxygen into the sample water and an air diffuser, and a stirrer for stirring the sample water.
OD measuring device.