JP2000069955A - Activity evaluation testing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an activity evaluation testing system by promptly metering the oxygen consumption rate with high accuracy. SOLUTION: The reactor (4) is equipped with a means metering the oxygen dissolved (DO) in the liquid in the reactor (4) and a means metering the oxygen (O2) in the upper gas phase and a certain amount of a microorganism mixture is introduced into the reactor (4) from the microorganism mixing tank (2) on the outside by evacuating the inside of the reactor (4). The activity of a microorganism is evaluated by metering the DO concentration in the culture mixture and the O2 concentration in the gas tightly closed in the upper part (4a) of the reactor (4).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an activity evaluation test apparatus, and more particularly to an activity evaluation test apparatus for monitoring the condition of a treatment apparatus and evaluating the activity of microorganisms such as organic matter oxidation and nitrification in biological treatment of wastewater. The present invention relates to an activity evaluation test device for measuring an oxygen consumption rate.

[0002]

2. Description of the Related Art In a method of biologically treating organic substances and nitrogen components in wastewater, oxidation of organic substances and nitrification reaction of ammonia nitrogen are generally used. Because these reactions involve oxygen consumption by microorganisms, based on the rate of oxygen consumption,
It is possible to monitor the condition of the processing apparatus and evaluate the activity of microorganisms such as oxidation of organic substances and nitrification.

[0003] As a method of measuring the oxygen consumption rate of microorganisms in a wastewater treatment apparatus, a mixture of microorganisms is collected from a treatment tank into a small reactor outside the tank, and the microbial reaction proceeds in the reactor in batches. Methods for determining the rate of oxygen consumption are known. As a method for obtaining the oxygen consumption rate of the microorganism mixture collected in the reactor, a dissolved oxygen concentration meter (DO meter)
The following method using an oxygen concentration meter (O ₂ meter) in the gas phase is known.

A) Air is supplied to the reactor, and a mixture of microorganisms is supplied.
In the gas discharged from the gas into the gas phase _TwoThe concentration is several mg / L
After increasing the air supply to about
DO concentration reduction by DO meter while stirring biological mixture
Measure the speed. b) Supply air to the reactor to convert the microorganism mixture into the gas phase.
O in exhaust gas _TwoO concentration_TwoMeter and supply empty
O in the atmosphere_TwoFrom the difference from the concentration and the amount of air supplied, acid
Calculate the elementary consumption speed. When the DO concentration changes
Measures the rate of change of the DO concentration with a DO meter,
Correct the speed.

C) While supplying air to the reactor, the DO concentration of the mixture of microorganisms is measured, and the oxygen consumption rate is calculated from the change rate and the overall oxygen transfer capacity coefficient (K _La ). The method a) is used to measure only the initial oxygen consumption rate of the mixed solution in the reactor, since the measurement ends when the DO concentration of the mixed solution becomes 0 mg / L.

On the other hand, in the methods b) and c), since the air is continuously supplied, the transition of the oxygen consumption rate accompanying the microbial reaction in the reactor can be continuously measured. However, the method b) has a problem that when the reactor is a small vessel, the difference between the O ₂ concentration in the exhaust gas and that in the atmosphere is very small, and the measurement error of the oxygen consumption rate is relatively large. is there. Method c) requires only a DO meter to convert the oxygen consumption rate using K _La which is an indirect index, and the apparatus is simple. However, the correlation with water temperature, air flow and other parameters can be grasped. Therefore, there is a problem that the measurement becomes complicated.

[0007]

When the mixed liquid of microorganisms in the treatment tank is collected in the reactor, the activity of the microorganisms and the water quality of the mixed liquid change every moment. Need to be done. For this reason, a high-speed flow pump is usually used to collect the mixed solution. At this time, the mixed solution comes into direct contact with the high-speed rotating part of the pump, so that the flocs of microorganisms in the mixed solution are destroyed. There was a case. Further, when the mixture contains a carrier having microorganisms immobilized on the surface or inside thereof, there has been a problem that the microorganisms may be peeled off from the surface of the carrier, and in some cases, the carrier itself may be worn or destroyed.

As a method of collecting a mixed solution in a reactor without using a liquid sending pump, there is known a method of reducing the pressure in the reactor by a pressure reducing pump and sucking the mixed solution into the reactor at the negative pressure. ing. The apparatus for carrying out this method is that, when the reactor is depressurized and the inflow valve is opened, the external liquid is sucked into the reactor, and when the liquid level reaches the level gauge installed in the reactor, The inflow valve is closed, the atmosphere valve is opened, and the gas phase is returned to atmospheric pressure. And after the measurement,
The liquid inside is discharged from the discharge valve, and the process proceeds to the next liquid collecting step. According to this device, the mixed solution does not directly contact the high-speed rotating part of the pump, the flocs of the microorganisms in the mixed solution are not destroyed, and the mixed solution further fixes the microorganisms on the surface or inside. When a carrier is used, an external liquid can be collected into the container at a high flow rate without peeling of microorganisms from the surface of the carrier and in some cases abrasion or destruction of the carrier itself.

However, when introducing a DO meter and an O ₂ meter for measuring the DO concentration in the internal mixture and the O ₂ concentration in the upper gas into this reactor, the DO at the time of collecting the mixture is required. The time for the meter to contact the mixture is short,
Inadequate response to concentration. Therefore, when the measurement of the DO concentration change of the mixed solution is started after the end of the collection, a delay in response occurs and accurate measurement cannot be performed. Further, it becomes vessel is depressurized state during collection of the liquid mixture, the O ₂ concentration for the indicated value of the O ₂ concentration and O ₂ meter in the gas is decreased, and the gas phase to atmospheric pressure after collection finished gas When the measurement of the change is started, a response delay occurs, and accurate measurement cannot be performed.
Further, when a conventional DO electrode in which an electrolyte is held in a diaphragm is introduced into this reactor, when the inside of the reactor is depressurized (600 Toor or less) to collect a mixed solution, DO Abnormalities such as an extremely high reading temporarily appearing on the electrode may not be enough to respond to the DO concentration of the sampled liquid mixture. When starting, a response delay occurred, and accurate measurement could not be performed.

The present invention has been made in view of such circumstances.
It eliminates the disadvantages of the prior art described above,
Collect the liquid in a reactor and measure the rate of oxygen consumption by microorganisms
In the device, the destruction and burden of microbial flocs in the mixture
Exfoliation and carrier of microorganisms immobilized on or in the body
Without causing wear and tear of itself, and even in the reactor
DO concentration of collected microorganism mixture and O in upper gas phase_TwoDark
At the start of the measurement of the degree change, the DO meter and O_TwoMeter reading,
The initial DO concentration of the mixture and the O _TwoTo the concentration
Accurate measurement of oxygen consumption rate
To provide an activity evaluation test device capable of measuring
Aim.

[0011]

In order to achieve the above object, the present invention provides an activity evaluation test apparatus according to claim 1 of the present invention.
The reactor has means for measuring the concentration of dissolved oxygen (DO) in the internal liquid and the concentration of oxygen (O ₂ ) in the upper gas. It is configured to collect a fixed amount of the microorganism mixture into the reactor, and from the end of collection of the mixture into the reactor, while circulating the gas sealed in the upper part of the reactor into the mixture, The microbial activity is evaluated by measuring changes in the DO concentration and the O ₂ concentration in the gas.

According to a second aspect of the present invention, there is provided an activity evaluation test apparatus according to the first aspect, wherein the reactor is connected to a pressure reducing tank having a larger volume than the reactor, and the pressure reduction tank is used when collecting the microorganism mixture. By depressurizing the tank and sucking the microorganism mixture from the outside into the reactor and then into the vacuum tank, the DO in the reactor was replaced while replacing the mixture in the reactor with the mixture from the outside. It is characterized in that the reading of the meter is adapted to the DO concentration of the mixture.

According to a third aspect of the present invention, in the activity evaluation test apparatus according to the second aspect, the position of the connecting pipe connecting the reactor and the pressure reducing tank is adjusted to the level of the mixed solution in the reactor. This is characterized in that a fixed amount of the mixed solution is collected in the reactor. Further, in the activity evaluation test device according to claim 4 of the present invention, the pressure is reduced by sucking outside air into the upper gas portion of the reactor at the end of the collection of the microorganism mixture in claim 1, 2 or 3. It is characterized by returning the pressure of the gas part to atmospheric pressure.

The cause of the abnormality in the indicated value of the DO electrode when the reactor is depressurized is that the electrolyte held in the diaphragm of the electrode is sucked into the reactor through the diaphragm. It was inferred from various studies that this is because cavitation occurs in the electrolytic solution. Therefore, a communication pipe is provided from the electrolytic solution part to the gas phase part of the reactor, which is also depressurized, so that an attractive force is generated in the electrolytic solution in a direction to cancel the suction force through the diaphragm.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the activity evaluation test apparatus of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of the activity evaluation test apparatus according to the present invention. This apparatus includes a microorganism mixing tank 2, a reactor 4, a decompression tank 6, and the like.

The lower end of the reactor 4 is connected to one end of an inlet pipe 8. The inflow pipe 8 has an intermediate portion raised and the other end immersed in the microorganism mixture 10 in the microorganism mixture tank 2. An inflow valve 12 is provided at an intermediate portion of the inflow pipe 8.
Are arranged. In addition, a connecting pipe 1 is provided above the reactor 4.
The other end of the connecting pipe 14 is arranged at the upper part (gas phase part) 6 a of the pressure reducing tank 6. Further, a DO meter 16 is provided above the reactor 4. The DO meter 16 has a diaphragm 18 at its tip, and the diaphragm 18 is arranged at a position slightly lower than one end of the connection pipe 14. The DO meter 16 includes a communication pipe 20 having one end connected to the inside and the other end positioned higher than one end of the connection pipe 14. A circulation line 22 connecting the upper part (gas phase part) 4a and the bottom part is formed in the reactor 4, and a circulation pump 24 is provided in the middle of the circulation line 22.
A switching valve 26 is interposed between the circulation pump 24 and the upper portion 4a of the reactor 4, and a switching valve 28 is interposed between the circulation pump 24 and the bottom of the reactor 4.
The switching valve 26 selectively connects the upper portion 4a of the reactor 4 to the atmosphere or the circulation line 22, and the switching valve 28 selectively communicates the circulation line 22 to the bottom of the reactor 4 or the atmosphere. Things. Further, an O ₂ meter 30 is disposed between the circulation pump 24 and the switching valve 26 in the circulation line 22.

One end of a suction pipe 32 is connected to an upper part (gas phase part) 6a of the decompression tank 6, and a decompression pump 34 is installed in the suction pipe 32. One end of a drain pipe 36 is connected to the bottom of the decompression tank 6, and the other end of the drain pipe 36 is connected to the microorganism mixing tank 2. And
A drain valve 38 is interposed in the drain pipe 36. Further, a liquid level gauge 40 and an opening valve 42 are provided above the decompression tank 6.

In the activity evaluation test apparatus according to the present invention, the gas phase part (upper part) 4a of the reactor 4 has a closed structure, and the exhaust gas from the mixture of microorganisms in the reactor 4 is supplied to the reactor 4 by the circulation pump 24. And the DO concentration and O ₂
It measures each change in concentration. And D
The rate of change of each of the O concentration and the O ₂ concentration and the mixture;
The oxygen consumption rate is calculated from the volume of the gas phase.

An operation example in which a sample (mixture of microorganisms) is collected by the present apparatus and the rate of oxygen consumption is measured based on FIG. 1 for each process is as follows. Sampling The reactor 4 is shut off from the atmosphere by the switching valve 26 of the reactor 4, the opening valve 42 is closed to shut off the depressurizing tank 6 from the atmosphere, and the depressurizing pump 34 is operated. 4 is depressurized by the decompression pump 34. Then, when the inflow valve 12 of the inflow pipe 8 is opened, the mixed solution 10 is sucked from the microorganism mixing tank 2 into the reactor 4 and then into the decompression tank 6. When the pressure-reducing tank 6 is filled with a predetermined amount of the liquid mixture and the liquid level reaches the contact tip of the liquid level gauge 40, the inflow valve 12 is closed to terminate the collection of the liquid mixture. Subsequently, the switching valve 26 is operated to open the reactor 4 to the atmosphere, and the opening valve 42 is opened to open the pressure reducing tank 6 to the atmosphere.
Then, the gas phase part 4a in the upper part of the reactor 4 is exchanged with the outside air, and returns to the atmospheric pressure together with the gas phase part 6a of the pressure reducing tank 6.
As a result, a certain amount of the mixed liquid is collected in the reactor 4 at the same liquid level as the opening position of the connection pipe 14. The excess mixed solution remaining in the decompression tank 6 is thereafter returned to the microorganism mixing tank 2 by opening the discharge valve 38 at an appropriate time. When the mixed solution is collected, the gas phase 4a of the reactor 4
A circulation line 22 extending from the reactor to the bottom of the reactor 4 is provided with a switching valve 2
It is isolated from the reactor 4 by 6 and the switching valve 28, and communicates with the atmosphere via their switching valves 26 and 28, at the same time, passed through the outside air into O ₂ meter 30 in the line by the circulating pump 24, O ₂ A total of 30 calibrations are performed.

In this activity evaluation test apparatus, the pressure reducing tank 6
Is made larger than that of the reactor 4. Therefore, the mixture in the reactor 4 is completely exchanged, and the DO meter 16 provided in the reactor 6 can come into contact with the continuously exchanged mixture during the mixture sampling, and the DO meter 1
6 becomes equal to the DO concentration (initial value) of the mixed solution. The contact time between the mixed solution and the DO meter 16 until the collection is completed depends on the volume of the decompression tank 6, the height of the liquid level gauge 40, the suction amount of the decompression pump 34, the inflow pipe 8, the connection pipe 14 and the like.
Can be easily adjusted by the inner diameter, length, etc., and is usually set to 0.5 to 3 minutes. Measurement of Oxygen Consumption Rate of Sample After collecting the mixed solution in the reactor 4, the switching valve 26 and the switching valve 28 are operated to connect the circulation line 22 to the reactor 4, and the closed reaction is performed by the circulation pump 24. After the gas in the gas phase part 4a of the vessel 4 is communicated with the O ₂ meter 30 in the line,
The mixed solution in the reactor 4 is supplied from the bottom of the reactor 4. At the end of the sampling of the mixture, the DO meter 16 indicates the initial DO of the mixture.
The concentration is shown, and the calibration of the O ₂ meter 30 is completed using the outside air, and the gas in the gas phase portion 4 a of the reactor 4 is also replaced with the outside air. D of mixed solution accompanying oxygen consumption by microbial reaction
Changes in the O concentration and the O ₂ concentration in the gas can be accurately measured.

The oxygen consumption rate can be obtained from the following equation (1).

[0022]

(Equation 1) In addition, the activity evaluation test apparatus of the present invention is not limited to the above embodiment, and various changes can be made. For example, the inflow valve 12 is interposed in the inflow pipe 8, the inflow pipe 8 is opened by opening the inflow valve 12, and the inflow pipe 8 is closed by closing the inflow valve 12. By opening the valve, the inflow pipe 8 is opened to the atmosphere so that the mixture in the microorganism mixing tank 2 can be prevented from flowing into the reactor 4. In this case, it is necessary to install the atmospheric valve at a position higher than the opening position of the connecting pipe 14 in the reactor 4. Further, the operation timing of each valve can be appropriately changed within a range in which the object of the present invention can be achieved.

[0023]

FIG. 2 shows an example of measuring the oxygen consumption rate by the above-described activity evaluation test apparatus. In this example, a mixed solution of a carrier (3 mm square) on which nitrifying bacteria were immobilized and floating activated sludge was collected from a nitrification tank in a sewage nitrification and denitrification process. At the start of measurement (initial stage), the O ₂ concentration in the gas of the reactor (expressed in%) shows almost 21%, which is almost the same as the atmosphere, and decreases with the progress of the microbial reaction, reaching nearly 17% after 30 minutes. I have. The DO concentration initially shows about 5 mg / L,
It reaches 6 mg / L after 0 minutes. Each measured value every 20 seconds and the V _L = 1.6 L, the V _G = 0.4 L to the original, also shown in FIG. 2 the result of calculating the oxygen consumption rate K _r. K _r is
The initial value was about 30 mg / L · h, which decreased with the passage of time. After about 20 minutes, a stable result was obtained at about 10 mg / L · h.

In the above activity evaluation test apparatus,
Under the reduced pressure of 00 to 600 Torr, the abnormality of the indicated value of the DO meter, which was observed in the conventional apparatus, could be solved. At 400 Torr or less, if the depressurized state continues for 2 minutes or more, O ₂ precipitates from the liquid in the reactor, and the DO
It is preferable to avoid such operation because the concentration itself changes.

[0025]

As described above, in the activity evaluation test apparatus of the present invention, the mixture in the microorganism mixing tank is introduced into the reactor by utilizing the negative pressure without passing through the pump. The microbial floc is not destroyed, the microorganisms immobilized on the surface or inside of the carrier are not separated, and the carrier itself is not worn or destroyed. O ₂ in the measurement starting concentration change, the indicated value of the DO meter and O ₂ meter by reliably keying the O ₂ concentration of the initial DO concentration in the atmosphere in each mixture, quickly and accurately the oxygen consumption rate Can be measured.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of an activity evaluation test apparatus according to the present invention.

FIG. 2 is a characteristic diagram showing the oxygen consumption rate, DO concentration and O ₂ concentration obtained by the activity evaluation test apparatus of FIG.

[Explanation of symbols]

2 ... Microorganism mixing tank 4 ... Reactor 4a ... Gas phase 6 ... Decompression tank 6a ... Gas phase 8 ... Inflow pipe 10 ... Microorganism mixture 12 ... Inflow valve 14 ... Connecting pipe 16 ... DO meter 18 ... Diaphragm 20 ... Communication tube 22 ... circulation line 24 ... circulation pump 26, 28 ... switching valve 30 ... O ₂ meter 32 ... suction pipe 34 ... vacuum pump 36 ... drain pipe 38 ... exhaust valve 40 ... liquid level meter

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuki Nakamura 1-1-1 Uchikanda, Chiyoda-ku, Tokyo Inside Hitachi Plant Construction Co., Ltd. (72) Hitoshi Yoshikawa 1-1-1, Uchikanda, Chiyoda-ku, Tokyo No. 14 Inside Hitachi Plant Construction Co., Ltd. (72) Inventor Masahiro Midorikawa 9-15 Mizobata-cho, Sakado-shi, Saitama (15-203) F-term (reference) 4B029 AA02 AA07 BB01 CC01 CC03 CC13 DA10 DB17 DF03 DF04 DF05 DF09 FA12 FA15 4D028 BC15 BC17 BC26 BD00 BD10 BD17 CA01 CA04 CA10 CB03 CB08 CC00 CC07 CC09 CC15 CD04 CD05

Claims (4)

[Claims] 1. The reactor has means for measuring the concentration of dissolved oxygen (DO) in the internal liquid and the concentration of oxygen (O ₂ ) in the upper gas. Is configured to collect a fixed amount of a mixed solution of microorganisms from the microorganism mixing tank into the reactor, and from the end of collection of the mixture to the reactor, the gas sealed at the top of the reactor is mixed into the mixed solution. An activity evaluation test device for evaluating microbial activity by measuring changes in the DO concentration of a mixture and the O ₂ concentration in a gas while circulating. 2. The method according to claim 1, wherein said reactor is connected to a vacuum tank having a larger volume than said volume,
By decompressing the decompression tank and sucking the microorganism mixture from the outside into the reactor and then into the decompression tank, the mixture in the reactor is replaced with the mixture from the outside while preparing the reactor. The indicated value of the DO meter
The activity evaluation test device according to claim 1, wherein the device is configured to be adjusted to the O concentration. 3. A fixed amount of the mixture is collected in the reactor by adjusting a position of a connecting pipe connecting the reactor and the pressure reducing tank to a level of the mixture in the reactor. The activity evaluation test device according to claim 2, wherein: 4. The method according to claim 1, wherein when the collection of the mixture of microorganisms is completed, outside air is sucked into the upper gas portion of the reactor to return the reduced pressure of the gas portion to the atmospheric pressure. 4. The activity evaluation test device according to 2 or 3.