JPS63193064A - Method and apparatus for measuring oxygen utilizing speed - Google Patents

Abstract

PURPOSE:To continuously perform highly accurate measurement undergoing little error, by immersing one end of an aeration column in specimen water to make the immersion ratio thereof constant. CONSTITUTION:An aeration column 1 and a measuring column 2 are integrally constituted and demarcated by a partition wall 3. Dissolved oxygen (DO) meters 5, 6 are provided to the measuring column 2 and floats 7 are mounted to the arbitrary positions of the integrally formed columns 1, 2. Since the columns 1, 2 are floating in an aeration tank by the floats 7, the immersion ratio of the column 1 becomes constant even when a water level varies. Further, since the capacity of an air lift pump 8 is determined by an air flow rate and the immersion ratio, by properly selecting the air flow rate and the immersion ratio, water pumping-up amount is determined. The specimen water pumped up by this method passes through the DO meters 5, 6 to measure the DO value of the specimen water. The difference between the measured values of the DO meters 5, 6 is divided by a passing time to make it possible to measure an oxygen utilizing speed.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method and apparatus for measuring the oxygen utilization rate (rr) carried out when wastewater is treated by the total activated sludge method.

B1 Overview of the Invention The present invention provides an aeration force ram for water testing by four people.
In the device to be measured, one end of the aeration column is completely immersed in the test water at a constant immersion rate, and after the entire test water introduced into the aeration column is aerated, the first and second dissolved oxygen (DO) are measured. D04 in total! Measure. Then, when the time sound Δt is the time the sample water reaches from the first DO meter to the second DO meter, find the difference between the output value from the second DO meter and the output value from the first DO meter, and calculate this difference. Sound△
By dividing by t to find the rr value, r and [k can be measured continuously and with high precision.

C1 Conventional technology In the IA sludge method, which is used as a method to treat wastewater containing large amounts of organic matter, such as urban sewage and food factory wastewater, if the aeration in the aeration tank becomes excessive, the sludge becomes fragmented. This is not stupid and will lead to an increase in power consumption.

Conversely, if there is insufficient aeration, activated sludge will rot.
Deposition occurs at the bottom of the tank and the quality of the treated water deteriorates. In order to optimally manage the aeration tank, it is necessary to maintain oxygen at a rate equal to or greater than the oxygen utilization rate (respiration rate) of activated sludge. must be supplied.

The rr of the mixed liquid in the aeration tank is expressed as the amount of oxygen (mg/4·hr) utilized by a unit volume·(t) of the mixed liquid within a unit time (hour). The utilization rate coefficient (Kr) is the amount of oxygen (mg/g) utilized by unit weight (g) of activated sludge within unit time (hour).
・hours), and this Kr is an index representing the activity level vI of activated sludge. These r, , and Kr are both measured as indicators for monitoring the inflow of poison proboscis (a substance that suppresses the activity of activated sludge).

The method for measuring the #RX utilization rate using the sewage test method is to collect 5 gk in the aeration tank, let it stand still for 10 to 20 minutes, then separate the upper fresh water with a 7-siphon siphon, and measure the dissolved oxygen in the supernatant water. (DO) is approximately 5mg71 or more.
Aerate vigorously for ~10 minutes to allow sedimentation during separation, then stir well with the sludge. Fill an upper Erlenmeyer flask with this mixture to 300 mtK, insert the DO elbow joint to prevent air from entering, and immediately stir with a magnetic stirrer to measure the change in DO over time. (However, if the DO value of the mixed liquid in the aeration tank is about 5 mg/or more, the measurement may be performed immediately.) , find the value.

r, (mg/l・hr) = oxygen utilization! (mg/L)/Elapsed time (hours) D1 Problems to be solved by the invention The method of measuring rrt as described above requires rounding by manual analysis, a scale that cannot perform continuous measurement, or a complicated operation. This makes optimal control using r or Kr difficult. In addition, a m degree change in the sample greatly affects the measured value, but it is impossible to collect the sample at the same temperature as the aeration tank and perform the entire process manually, so there may be errors in the measurement results. will occur. Furthermore, among measurement operations.

Even if you increase the Do value by performing aeration without performing siv for the solid-liquid content of the sample, no difference in the data will be observed, and the separation operation will be a meaningless operation, and the time required for aeration before starting the measurement will increase. Affect measurement results. There are also reports such as 9, but in any case, it is not an effective method for measuring rr.

Therefore, many attempts have been made to solve these problems, and one method among them is Jour.
nal WPCP, Vol 56. No. 4. P
319.

In 1984, DO values were measured and the overall oxygen transfer capacity coefficient (
A method of calculating from the KLa) value as follows is shown. The equation for oxygen transfer in the aeration tank is shown below. (When there is no running water) a stone = KLa (Ca-c) - r, -+m+++ (1)
However, for C8, the saturated beauty of the mixed liquid in the aeration tank [(
mg/l), C is the mixed liquid OD in the aeration tank
O value (mg/!), KL a indicates the oxygen supply capacity in the aeration tank circle, and the tank structure and air diffuser q! ! The value of existence comes out. The method for measuring KLa has been extensively studied.1 For example, by stopping the inflow and outflow to the aeration tank, and increasing the amount of air in the aeration tank in several stages.
/#, and the DO value at 9 when each stage becomes steady,
rr value (one pair of air (K L a constant number) CIZ
) Find the r1 value from the change).

KL and rc are actually influenced by water temperature and activated/sludge suspended vJ'X concentration (MLSS), but the biggest influence is the amount of air. Therefore, use this method to find the relationship between KL and the air flow rate. When the aeration tank is in operation, KL is calculated from the air flow rate, and Do@[j? ! rrmk is estimated from the measured values of the change in the value and the change thereof using the following equation.

F da rr” (Ci C) + KLa (Cs C)
,,・・・・・・・・・(2) ■ Equation (2) is the equation when inflow water is continuously supplied, where Ci is the inflow water DO value (mg/l) and p is the inflow amount(
(inflow water + return sludge), v is the aeration tank capacity.

Although this method has the advantage of continuously obtaining r values,
If KLa changes due to factors other than the air flow rate, there is a problem in that an error occurs in the value of r.

Therefore, purpose #2 of the present invention 811 is to provide a method and apparatus for measuring objects continuously with few errors.

Means for Determining E6 Spot Point Km First of the present invention, the DO value after aerating the test water introduced into the aeration column is used to determine r and value t.
#l In a test, one end of the aeration column is immersed in the test water to maintain a constant immersion rate. It is introduced into the aeration column 7 with a constant immersion rate, and after aeration is carried out to detect the ratio, it is flowed from the first DO meter distribution position to the second DO distribution position, and when the time at that time is tΔt,
Find the difference between the output value of the second adder and the output value of the first Do meter.

The r value is determined by dividing this difference by Δt.

Further, in the second invention, as a means for keeping the immersion rate constant, a flow) is attached to the aeration column, and the characteristics of the air lift pump are used to pump up the sample water. An overflow wall is installed in the aeration column, and the overflow sample water is %@1. 1st. Arrange the needle so that it flows into the measuring column where the Do needle is placed.
bottomed out.

Since the F0 action aeration column is suspended in the test water by a float, the immersion rate remains constant even if the water level in the aeration tank fluctuates. The performance of an air lift pump is determined by the air flow lid and immersion rate, so the amount of water pumped is determined by selecting the appropriate amount of air @t and immersion rate. The test water pumped in this way was the first sample. Second DOftt-
The Do value at the time of passing is measured, and the r value can be measured by dividing it by the time Δt of passing on the measuring device with each Do meter.

G. Example Embodiment 2I of the present invention will be described below based on the figures.

First, before explaining the present invention, the basic principles of its measurement will be explained in the third section.
Explain based on the diagram: How to operate the sampling pump k [to sample (test water)?] The mixture is injected into an aeration column 20, and an appropriate amount of air is blown into the column 20 for aeration. The sample water after aeration is sent to the first DO measuring cell 21, g
The measuring force ram 22 is then transferred to the second DO measuring cell 23. Although no aeration was performed during this time,
A DO value is measured in each measuring cell 21.26. The next DO value measured by the first DO measurement cell 21 [:DOI
A and the next DO value (
(Do)B−(
A subtraction of DOIA is performed. Now, assuming that the flow is flowing between the first DO measuring cell 21 and the second Do measuring cell 26 with stirring in the middle being negligible, (1)
If KL = 0 in the equation, then da = - dt'. Assume that the drifting snow is controlled by the flow rate regulator 25 to be constant, and the time for passing through the measurement column 22t is tΔt.

When divided by the output tΔt of the subtractor 24, r is obtained.

It becomes possible to calculate values continuously.

Note that 26 is a constant temperature bath, and since the measurement of the r value is affected by temperature, the measuring device is placed in a constant temperature bath, and the regulator 27 and the control section 28
t-via! Adjusted by i degree. FIG. 1 shows an embodiment of the present invention put into practical use based on the principle shown in FIG.

In the figure, 1 is an aeration column, 2 is a measurement column, and the outer walls of each column 1.2 are integrally constructed, but a partition wall (overflow wall) is provided at an intermediate position.
The two are separated by 6. The upper part of the aeration column 1 is enlarged to form a defoaming part 1a, and in the lower part of the measurement column 2, there is a first DO meter 5 and a certain distance between this DO meter 5. A second Do meter 6 is attached. 7 is a float, and this float 7 is attached to any position of the integrally formed aeration column 1 and measurement column 2, and is placed in the test water tank (aeration tank) circle together with ctL et al. 1.2. The Nff force in aeration column 1 is held constant. 8 is an air pump, 9.10 is an amplifier, and the first and second
The DO value measured by a DO meter of 5.6 ttjlI width. 11 is a computing unit.

In addition, the immersion rate σ in this is stipulated by.

Figure 2 shows the characteristics of the air lift pump function, showing the relationship between the water pumping amount Qw (t/min) and the air flow rate QA (t/win) converted to atmospheric pressure, which is the immersion rate σt parameter of aeration column 1. It's a thing. That is, if the immersion rate σ is set to a certain value, the pumped water amount Qw will be constant as long as the air flow rate QA is controlled to be constant.

Next, the present invention will be explained in detail.

When the aeration column 1 attached to the float 7 is immersed in the aeration tank (actually, the measurement column 2 is also included at the same time), the column 1 floats with a portion of it th above the water surface. . This th remains constant even if the water level in the aeration tank fluctuates because it depends on the float installation position and column length.69. The immersion rate σ is, for example, σ=0.7 in FIG. When the air pump 8L is operated in this state, air is sent to the air injector 4 through the entire pipe, and is sent into the aeration column 1 from the injector 4. This ninth air is column 1
By rising inside the column 1, this column 1 becomes an air lift pump function, pumping up water from the test water 11F population 1b and overflowing it to the upper part of the overflow wall 3. At this time, the sample water 7'Lfc sucked into the aeration column 1 is not aerated by the air blown from the air injector 4 and reaches the defoaming section 1a, where the degassing section 1all? - The air pump 8 is defoamed and an amount corresponding to the inflow amount overflows as Qw, but in the air pump 8, the discharged air amount QA t-For example, by controlling it so that it becomes 20 t/min K, the pumped water amount Qw is approximately 9.517 min (a w
Q, 7) Q is constant. In other words, the performance of the aeration column 1 equipped with an air lift pump is determined by the air inflow contribution QA and the immersion rate σ.
By appropriately setting and σ, the inflow amount and aeration conditions within the column 1 can be obtained. The initial Do value of the overflowing Qw test water is measured by M17)DO1t5 in the measurement column 2, and the measured value DOm is amplified by the amplifier 9 and output to the calculation 611. Further, the final Do value of the sample water is measured by a DOO 40 disposed at the terminal end of the measurement column 2, and the value DOB is amplified by -610 and then output to the computing unit 11.

The sample water flowing through the measurement column 2 is constant due to the characteristics shown in Figure 2, so the sample water flows from near the first DO total 5 to the second DO
Assuming that the time required to reach O40 is Δt, the computing unit 11 is as follows.

The rr value is determined and output by performing the operation of equation (3). In this way, the stirring of the sample water in the measurement column 2 can be ignored, and the measurement column 2 can be measured and the OB and DOA
Of course, the pipe length and diameter should be selected so that a difference in the amount of water can be obtained.

Effect of H1 invention According to the present invention, the following effects can be obtained.

(1) When sampling sample water with an aeration column, sampling and aeration are performed at the same time using the air lift effect, so it is possible to perform measurements in which the sample water is injected into the aeration column and then aeration is performed. It is possible to continuously measure rrmk without performing a ninth switching operation.

(2) The amount of sample flowing into the aeration column and the degree of the aeration effect can be easily designed from the characteristics of the air lift pump. That is, if the immersion rate σ is set small, the amount of sample flowing in decreases, and the time required to receive aeration in the aeration column 7 becomes longer.This can be easily designed depending on the pump characteristics.

(3) Since the aeration column can always maintain a constant immersion rate using a float, as long as the air flow rate remains constant, the sample flow rate can be kept constant even if the water level in the aeration tank fluctuates. (
3) Assuming that Δt in the equation is constant, the rr value can be calculated easily and with high precision.

(4) Most of the aeration 7 column and measurement column, which are the flow paths for the test water, are submerged in water in the aeration tank! There is little influence from changes in degree, and stable measurement is possible without using a constant leakage tank or the like.

(5) Since it is an immersion type and has a simple structure that does not require any mechanical sampling equipment such as piping, it is possible to obtain a device that does not cause trouble due to foreign matter in the tank.

(6) Since the measurement is continuous, it has an excellent effect as a signal for control and as a monitor for the inflow of toxic substances.

[Brief explanation of the drawing]

Fig. 1 is a seven-wire configuration diagram of an embodiment of the present invention, Fig. 2 is a QW-QA relationship diagram that will be explained next, and Fig. 3 is a diagram showing the relationship between QW and QA.
It is an explanatory diagram of the ninth principle of one constant. 1 is the aeration column, 2 is the measurement column, 5Fi bulkhead (overflow wall) 4 is the air injector, 5゜6 is Do! t
t, 7 is float, 8 is air pump, 9゜10 is increase II
Ia unit, 11 is an arithmetic unit. Figure 1 Figure 2 Large rough pressure conversion! Frozen volume Qa (17 m1n) - Figure 3 procedural amendment (.e. June 2, 1988

Claims (5)

[Claims] (1) In a system in which a test water is introduced into an aeration column and the oxygen utilization rate is measured using the dissolved oxygen value after aeration of the introduced test water, one end of the aeration column is is immersed in the test water to keep the immersion rate constant, and the time required for the test water after aeration to reach the vicinity of the second dissolved oxygen meter from the vicinity of the first dissolved oxygen meter is determined by Δ.
A method for measuring the oxygen utilization rate, characterized in that the measurement is carried out by dividing the difference between the detected output value of the second dissolved oxygen meter and the detected output value of the first dissolved oxygen meter, where t is Δt. . (2) The method for measuring oxygen utilization rate according to claim 1, characterized in that aeration and water sampling are performed simultaneously. (3) When measuring the oxygen utilization rate using the dissolved oxygen value after introducing test water into an aeration column and aerating the introduced test water, one end is immersed in the test water. The aeration column is held at a constant immersion rate by a support means, and an air injector is provided at the lower part of the immersion side of the held aeration column for discharging air sent out from an air pump, and furthermore, the water level of the sample water is An overflow wall is provided on one side of the aeration column projecting upward, and a measurement column is provided to introduce the test water that has overflowed the overflow wall. An apparatus for measuring oxygen utilization rate, characterized in that a second dissolved oxygen meter is provided. (4) The oxygen utilization rate measuring device according to claim 3, wherein the supporting means for the aeration column is a float. (5) The oxygen utilization rate measuring device according to claim 3 or 4, characterized in that an aeration column protruding above the water surface of the test sample is provided with a desulfurization section.