JPH0457399B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sludge management device used in a sewage treatment system.

Sewage treatment system includes respirometer, initial sludge concentration
Measuring devices such as MLSS concentration meter and sludge volume index meter (SVI meter) are used. Among these, the SVI meter is used in the above-mentioned sludge management equipment. This SVI meter performs a batch sedimentation test using a sludge sedimentation tube, and calculates the sludge volume (SV ₃₀ ) relative to the initial volume after 30 minutes of sedimentation.
This device calculates an index of sludge settling property called SVI (sludge volume index), which is obtained by dividing the amount by the MLSS meter. If this SVI meter is used for sludge management, there is no information on sludge settling properties obtained from the progress of sludge settling, so detailed sludge properties cannot be grasped, making it difficult to realize advanced sludge management. .
Furthermore, if the SVI value is within the range of 50 to 150, good sludge settling properties are indicated, and SVI is expressed as the ratio of SV ₃₀ to MLSS. For this reason, two different types of SV ₃₀
If the same SVI values are taken for
Information on consolidation sedimentation rate, consolidation point, etc. will be lacking. As a result, it is no longer possible to clearly distinguish between the two types of sludge properties, making it impossible to optimally control the sludge with the difference, which may pose a problem in sludge management.

This invention was made in view of the above circumstances, and a turbidity meter sensor section is attached to the upper part of the sludge sedimentation that forms the SVI meter, and the turbidity of the supernatant water at a point in the middle of the sludge sedimentation test is measured. During the test, data on the interface height versus time is stored in memory, and after the test is finished, the above data and SV ₃₀ and MLSS data are processed in the calculation unit, so the sludge properties during sludge settling can be accurately determined. can be grasped,
It is also an object of the present invention to provide a sludge management device that can clearly distinguish the properties of different types of sludge, improve sludge management, and perform optimal control of sludge.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an aeration tank, and an inflow water pipe 2 is provided from the upper left side of the tank 1 to which inflow water from a first sedimentation tank (not shown) is supplied. Reference numeral 3 denotes a pipe line that leads the outflow water from the aeration tank 1 to the final settling tank 4. 5 is a pipe for discharging treated water from the final settling tank 4. The sludge deposited in the final settling tank 4 is returned to the aeration tank 1 via a return sludge pipe 7 by a pump 6. Further, the sludge drawn out by the pump 6 is introduced into the pipe line 8 as surplus sludge. Reference numeral 9 denotes a sludge management device, and this device 9 includes a sludge interface measuring device 9a (details will be described later) consisting of an SVI meter and a turbidity meter (TU meter), an interface sedimentation storage device 9b, and a sedimentation curve parameter calculation unit 9c.
and a measurement calculation result output device 9d. The output signal from the output device 9d activates the pump 10 that controls inflow water, and also activates the pump 6 for removing return sludge and excess sludge.

Figure 2 shows the sludge interface measuring device 9a shown in Figure 1.
In this figure 2, which is a configuration diagram showing the details, 11
1 is a sludge settling tube formed from a cylindrical body made of glass, and a test water inlet 13 connected to an air lift pump 12 is provided at the upper part of this settling tube 11 . The lower end of the air lift pump 12 is immersed in the aeration tank 1. On the outer periphery of the sedimentation tube 11, a projector 14a and a receiver 14b, which can be raised and lowered, are attached to a support member 15, and the support member 15 is attached to a conveyor 16. The conveyor 16 is controlled by a lifting motor 17. This lifting motor 17 is controlled by a sludge volume (SV) detection drive section 18.This SV detection drive section 18 has an analog level switch 18a to which the output of the light receiver 14b is input.
An amplifier 18 that amplifies the output of this switch 18a
b, and a detection unit drive control circuit 18c to which the output of the amplifier 18b is input.

A potentiometer 17a is provided on the rotating shaft of the lifting motor 17, and the output of this potentiometer 17a is input to the SV measurement circuit section 19. This circuit section 19 is composed of an input adjustment circuit 19a and a voltage V-current I conversion section 19b, the output of which is input to a sedimentation curve parameter calculation circuit 20. 21 is an MLSS detector, and the output of this detector 21 is input to the MLSS measurement circuit section 22. this
The MLSS measurement circuit section 22 is an input adjustment amplifier circuit 22
a, arithmetic circuit 22b, hold circuit 22c and V
-I converter 22d. The output of the MLSS measurement circuit 22 is sent to the parameter calculation circuit 20.
is input.

As shown in FIG. 3, the sedimentation tube 11 is provided with a protrusion 11a at its upper part, and a turbidimeter sensor section 23 is housed in the protrusion 11a. The output of this sensor section 23 is input to the TU measurement circuit section 24. The TU measurement circuit section 24 is composed of an input adjustment circuit 24a, a VI converter 24b, and a memory circuit 24c. The output of this TU measurement circuit 24 is transmitted to the parameter calculation circuit section 20.
is input. The parameter calculation circuit 20 calculates each of the inputs and supplies the results to the output device 25. The output device 25 corresponds to the measurement calculation result output device 9d shown in FIG. In addition, in the figure, 26 is a power cylinder, 27 is a drain, 28
is a blower, 29 is an air solenoid valve for stirring, and 30 is a drain port.

Next, the operation of the embodiment configured as described above will be described.

First, the sludge settling pipe 11 is connected to the air lift pump 12.
Inject sludge from The sludge injected into the settling tube 11 begins to settle as time passes. Data on the interface height with respect to this sedimentation start time is obtained by the turbidity meter sensor unit 23, and the TU measurement circuit unit 24
The data is stored in the memory circuit 24c.

On the other hand, the sludge volume SV ₃₀ with respect to the initial volume after settling for 30 minutes is measured by the SV measurement circuit section 19 using SVI as in the conventional case. Further, the MLSS measuring circuit unit 22 performs MLSS measurement, and the arithmetic circuit 20 processes the MLSS, SV ₃₀ , and each data measured by the TU measuring circuit unit 24. This calculation processing result [uniform sedimentation velocity, consolidation sedimentation rate, consolidation point (time, interface height), tangent line and SVI value at the consolidation point, supernatant water turbidity during the sedimentation test, measurement time, etc.] and sedimentation curve data is supplied to the output device 25.

Hereinafter, the operation of the arithmetic processing of the above embodiment will be described using the characteristic diagrams shown in FIGS. 4 to 6.

(1) The sludge interface measurement time required to obtain reliable data varies depending on the SVI value.
As determined from the actual data of the relationship between SVI and consolidation start time (t _c ) shown in Figure 4, the required measurement time T _n =a x SVI + b (b≧30 minutes), (a is the slope shown in Figure 4) ) to determine.

This calculation is also performed in the calculation circuit 20 and the measurement time is automatically set.

(2) The Roberts constant, which expresses the consolidation sedimentation rate, has a linear relationship between the Roberts constant and SVI from the actual data obtained in the sewage treatment system as shown in Figure 5, so log kr=a ₁ ×SVI+log b ₁ , i.e. kr=
It can be expressed by the formula b・e ^a1×SVI . Therefore SVI
The arithmetic circuit 20 calculates the Roberts constant k _r using the above equation.

(3) At the same time as the SVI is determined, the calculation circuit 2 performs the calculation to obtain the consolidation start time (t _c ) using the relationship shown in Figure 4.
Do it with 0.

(4) Next, when the consolidation start time (t _c ) is obtained,
Based on the data actually obtained in the sewage treatment system of the consolidation point height (H _c ) and time (t _c ) shown in FIG. 6, the following equation can be obtained.

log H _c =a ₂ log t _c +log b ₂ or H _c =b ₂ ·t _c ^a1 The processing of the above equation is performed in the arithmetic circuit 20.

(5) In the Roberts consolidation-sedimentation curve equation, the last parameter H~ is calculated when the ratio of H~ and SV ₃₀ is 0.6~
Since it was experimentally confirmed that it takes a constant value between 0.8, from H~/SV ₃₀ = α, H~ = α・
SV ₃₀ and H~ can be determined.

(6) Performing the processing from (2) to (5) above in the arithmetic circuit 20,
Roberts' consolidation-sedimentation curve equation is expressed as H _t = H ~ + (H _c −
H~)e ^-(t-tc) (H _t : interface height at time t)
Determine. Furthermore, the uniform sedimentation velocity V _s in the uniform sedimentation area is the uniform sedimentation velocity V _s at time t.
(t) as v _s (t)=H _t +△t +H _t /△t or
The arithmetic circuit 20 calculates H _t −Δt −H _t +Δt/2Δt. Furthermore, the tangent line at the consolidation point is the average value of the sedimentation velocity before and after the consolidation point, and the slope of the tangent line is a ₃ , and from the relationship a ₃ ×t _c = b ₃ −H _c , b ₃ = H _c + a ₃ × t _c is obtained, and the tangent equation H _s
= a ₃ t + b ₃ can be determined.

(7) Therefore, the above calculations allow us to understand the settling state of sludge using parameters such as uniform settling velocity, consolidation settling velocity (Roberts constant), pressure contact point (t _c , H _c ), tangent at the consolidation point, and SVI value, The supernatant water turbidity during the sedimentation test, measurement time, measurement date and time] and sedimentation curve data are sent as digital values to the output device installed in the SVI meter. Using these sludge management indicators, it is possible to manage the sludge condition in the aeration tank and final settling tank.

As described above, according to the present invention, the following effects can be obtained.

(a) Conventional SVI meter has SV ₃₀ , MLSS, SVI
(SV ₃₀ / MLSS), but it was not possible to completely understand the sludge properties with the above parameters alone; however, at the same time, various parameters (uniform velocity Detailed information on sludge properties can be obtained from sedimentation rate, Roberts constant, etc.
Operation control of the aeration tank and final sedimentation tank can be performed reliably.

(b) In this invention, since a turbidity meter is attached to the upper part of the sludge settling pipe, the turbidity of the supernatant water can be monitored.

(c) Parameters representing the sludge interface sedimentation curve can be easily obtained from the relational expression obtained from experiments in actual sewage treatment systems, and traditional statistical calculations are not required, saving calculation time and memory. can.

(d) Since the sludge property information obtained from the parameters increases, sludge management becomes easier and advanced management in the aeration tank and final settling tank can be realized. For example, residence time in the final settling tank can be controlled by monitoring supernatant water turbidity.

(e) Conventionally, the measurement time of an SVI meter was changed manually, but the setting can be changed automatically using an arithmetic circuit.

(f) Recording the measurement calculation results on an output device such as a printer makes it easier to analyze and manage the calculation results.

(g) Furthermore, if the measurement and calculation results are input to the control device to control the return sludge pump, they can be used to manage the distribution of sludge in the aeration tank and the final sedimentation tank, and to manage the sludge in the final sedimentation tank.

(h) The algorithm for determining the slope a ₃ and the intercept b ₃ of the tangent at the consolidation point is simpler than before, and the calculation time can be shortened.

(i) As mentioned above, since the function to obtain the sludge settling state index has been added to the SVI meter, it is possible to improve the sludge management ability of the SVI meter.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention, FIG. 2 is a configuration diagram showing details of the main parts of FIG. 1,
FIG. 3 is a front view showing a state in which a turbidity meter is attached to a sludge settling tube, and FIGS. 4 to 6 are characteristic diagrams for explaining the operation of the embodiment of the present invention. 9a... Sludge interface measurement device, 9b... Interface sedimentation data storage device, 9c... Sedimentation curve parameter calculation circuit, 9d... Measurement calculation result output device, 11...
...Sludge settling pipe, 14a, 14b... Emitter, receiver, 17... Lifting motor, 18... SV detection drive section, 19... SV measurement circuit section, 20... Arithmetic circuit,
22... MLSS measurement circuit section, 23... Turbidity meter sensor section, 24... TU measurement circuit section.

Claims (1)

[Claims] 1. A movable interface position detector is provided on the outer peripheral surface of the sludge settling pipe, and an interface position signal from this detector is input to a calculation section, and the calculation section is provided with a sludge concentration detection section disposed inside the sludge settling pipe. A device that inputs the detection signal from the sludge sedimentation test and calculates the sludge volume index by calculating both signals in a calculation section, and a device that is attached to the upper part of the sludge settling pipe and measures the supernatant water turbidity at a point in the middle of the sludge sedimentation test. a turbidity meter sensor section, an arithmetic circuit that computes the output signal of the sensor section and an output signal of the device that calculates the sludge volume index, and an output device that outputs the computation results obtained by the arithmetic circuit. A sludge management device comprising: