JPS64118B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a computing device to collect various measurement data on the state of sludge in each process, which is an important indicator when operating and managing sewage purification facilities based on the activated sludge method. The present invention relates to a batch type activated sludge treatment device that automatically calculates the amount of wastewater and performs sewage treatment under rationally optimal conditions.

Each of the above indicators is expressed as follows according to JIS-KO102 "Industrial Wastewater Test Method" or "Sewage Test Method".

SVI=SV×10000/MLSS…(1) SDI=MLSS/SV×100=100/SVI…(2) MLSS=a×1000/sample volume (ml)…(3) SV=b/1000×100…( 4) In the above formula, SVI: Sludge volume index SDI; Sludge density index MLSS: Activated sludge suspended solids concentration of the mixed solution in the aeration tank [mg/] SV: Activated sludge settling rate of the mixed solution (standing for 30 minutes)
[%] a; Weight of activated sludge suspended matter in mixed liquid sample [mg] b; Capacity of precipitated sludge after standing still for 30 minutes in 100 ml of mixed liquid [ml] However, in formulas (1) to (4) above, The SVI of equation (1) is
The SDI in equation (2) is calculated using a calculation formula, but the SV and MLSS in that equation can only be obtained by analyzing the mixed liquid collected from the aeration tank. The SV in the reaction tank is expressed as SV=H ₀ /H ₁ ×100 (%) (5) where H ₀ is the sludge interface in the reaction tank, H ₁ is the lowest water level in the reaction tank. Additionally, the average residence time (SRT) of activated sludge cells can be calculated from the sludge drawing records.

Here, SRT is SRT = Amount of sludge in the reaction tank (W ₁ ) / Amount of sludge extracted (W ₂ )...(6) W ₁ and W ₂ are W ₁ = S x H ₁ x A... (7) W ₂ = q ×t×S×H ₁ /H ₀ ×n …(8) where S: MLSS concentration (at water level H ₁ ) [mg/] A: Reaction tank surface area [m ² ] q: Sludge extraction pump flow rate [m ³ /min] t: Operation time of the sludge extraction pump [min/times] n: Number of operations of the sludge extraction pump [times/day] From the above equations (6), (7), and (8), SRT=S×H ₁ ×A /q×t×S×H ₁ /H ₀ ×n =H ₀ ×A/q×t×n (9). And SV is, for example, the sample
Pour 1000ml into a measuring cylinder with an inner diameter of 6.5cm and a capacity of 1. After standing still for 30 minutes, settle the sludge volume and sample volume (1000ml).
ml) expressed as a percentage.

On the other hand, in MLSS, the sample is separated into suspended solids and liquid by a specified method such as centroid separation method or filter paper method, and then the solids are evaporated to dryness. Ratio to capacity [mg/
].

Since the above MLSS shows a good correlation with the amount of attenuation that occurs when a light beam or an ultrasonic wave is transmitted through the mixed liquid, a densitometer incorporating this method is used as the mounting device.

In other words, the conventional batch type activated sludge treatment control equipment uses a sludge interface meter as a means of knowing the interface height of settled sludge, and also uses a sludge interface meter as a means of knowing the MLSS concentration.
Since the MLSS meters were installed separately inside each batch reaction tank, the device configuration was complicated and economically disadvantageous. In addition, manual sludge extraction methods such as extraction pipes are often used to extract sludge, and the SS concentration of the supernatant liquid,
SVI and SRT also had the disadvantage of being processed without being sufficiently measured.

The present invention was made in order to eliminate the drawbacks of the conventional ones as described above.
The concentration detection means on the stand allows MLSS to be detected during the aeration process.
In addition to measuring sludge, the presence or absence of sludge at the set sludge interface height during the sedimentation process is also detected.
A device that can automatically drive sludge extraction means such as a pump by a calculation means that calculates sludge treatment measurement data based on the output signal from the concentration detection means and a controller that inputs the output signal from this calculation means. It is.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In Fig. 1, 1 is a batch type reaction tank, in which sewage is taken in through the sewage flow outlet 2, and in the discharge process after the aeration process and the precipitation process, the supernatant water is discharged through the supernatant water outlet 3.
More water is drained out of the tank. 4 has a concentration measuring section 5 at the bottom end.
The data measured by the densitometer 4 is transmitted via a signal line 6 to an arithmetic unit 7 as an arithmetic means having a built-in microcomputer or the like. and,
The calculation results are appropriately transmitted to the display 8 or printer 9 for appropriate output display. Also, 10
11 is an alarm device, and 11 is a controller. The output of the controller 11 drives a pump 12 as a sludge drawing means, and the precipitated sludge 13 is discharged to the outside of the batch reaction tank 1. In addition, the maximum water level height in the batch type reaction tank 1 is H ₂ , the minimum water level height is H ₁ , and the set sludge interface height is H ₀ (in order to prevent sludge from being discharged together with the supernatant liquid, the height is higher than the minimum water level height). ), and the concentration measuring section 5 is installed at a height of H ₀ . Moreover, FIG. 2 shows the measurement operation for each process of the batch type activated sludge control device shown in FIG. This is a measurement item measured by a total of 4.

Next, the operation of the present invention will be explained below with reference to FIGS. 1 and 2. First, the sludge in the batch reaction tank 1 is at a predetermined position near the height _H0 , and the concentration measuring part 5 of the densitometer 4 is immersed to perform the following operation.

(1) At the minimum water level height _H1 , when the aeration step S1 is started while flowing wastewater, after a predetermined set time _t1 has elapsed, the activated sludge suspended solids concentration MLSS is determined for the mixed liquid in the batch reaction tank 1. Measurement M1 is performed.

(2) The water level in the batch reaction tank 1 rises with the passage of time and enters the aeration step S2, but the measured value of the MLSS also changes in accordance with the change in the water level. Therefore, the set time t ₁ after the start of exposure is
By setting the minimum time for sufficient MLSS mixing, the water level at the time of MLSS measurement can be set approximately equal to the maximum water level height _H1 , so the water level at the time of measurement can be measured and the MLSS There is no need to convert.

(3) Next, in the sedimentation step S3, when the sedimentation of sludge has sufficiently progressed and the sedimentation is almost completed, the presence or absence of sludge at the set sludge interface height and the activated sludge concentration measurement for concentration detection M2 are carried out using the densitometer 4. This is done using
In other words, if the measurement result of the activated sludge concentration detection M2 at the set sludge interface height is a concentration higher than a predetermined set value (for example, 1000 mg/or higher), it means that the sludge interface is higher than the concentration measuring section 5. Therefore, the output signal of the densitometer 4 is transmitted to the arithmetic unit 7 via the signal line 6. That is, this calculation device 7 compares and calculates the actual sludge concentration measurement value based on the input signal from the densitometer and the preset sludge concentration value, and as a result of the calculation, the sludge concentration measurement value is When the sludge concentration exceeds the set value, a sludge extraction command signal is output to the controller 11. As a result, the controller 1
1 outputs a drive command signal to a pump (sludge drawing means) 12, and the pump 12 is driven by the signal, whereby the precipitated sludge in the batch reaction tank 1 is drawn out.

In addition, if the concentration of the measured value of activated sludge concentration detection M2 at the set sludge interface height is below the predetermined set value, it means that the sludge interface is below the concentration meter measurement part 5. No sludge extraction will be carried out.

In the above-mentioned sludge drawing, the output signal from the controller 11 is operated by a preset timer, so when the set time elapses, the pump 12 is automatically stopped and the settled sludge 13 is discharged. will be stopped.

(4) Next, when the sludge extraction is completed and the discharge step S4 begins, the sludge interface will be lower than the concentration measurement part 5, but if necessary, the presence or absence of sludge at the height _H0 of the predetermined position will be confirmed. together with the supernatant
Perform and record SS concentration measurement M3.

By performing the above series of control operations, the sludge interface is always maintained at a predetermined position near the height _H0 , and the sludge volume index SVI is immediately calculated by the calculation device 7 from the measurement results of the MLSS. Calculated. The calculation formula is shown in equation (1). In addition, the activated sludge cell average residence time SRT is calculated by equations (6) to (9), taking into account the operating time of the pump 12 for sludge extraction, and the respective calculation results are displayed on the display 8 or on the printer. The output is displayed by 9.

As described above, according to the present invention, it is only necessary to stationarily arrange the concentration measuring section of the concentration detecting means at a predetermined position in the batch reaction tank, and one concentration detecting means can be used to detect a single concentration. The activated sludge concentration during the aeration process in the batch reaction tank and the presence or absence of settled sludge at the set sludge interface height at the end of the settling process can be detected.

That is, the concentration detection means performs its original concentration detection function during the aeration process, and also detects the presence or absence of settled sludge at the set sludge interface height at the end of the settling process. The detection function is based on the arrangement level of the concentration measuring section of the concentration detection means, the concentration detection means that detects the activated sludge concentration at this arrangement level, and the actual sludge concentration detection by inputting the concentration detection signal from this concentration detection means. It is obtained by a combination of calculation means that compares and calculates the value with a preset sludge concentration setting value.

In other words, in this invention, the arrangement level of the concentration measuring section is a set sludge interface height, the concentration detection means detects the sludge concentration at this set sludge interface height, and the calculation means detects the concentration. The sludge concentration detected value based on the input signal from the means is compared with the sludge concentration set value, and when the sludge concentration detected value exceeds the sludge concentration set value, the actual amount of settled sludge in the batch type reaction tank is equal to the above set sludge interface. Therefore, if the detected sludge concentration value exceeds the set sludge concentration value, it is determined that sludge exists at the set sludge interface height, and the detected sludge concentration value exceeds the set sludge concentration value. If the value is not reached, it is determined that there is no sludge at the set sludge interface height.

In this way, the concentration detection means 1
It performs the normal activated sludge concentration detection function during the aeration process and the presence/absence detection function of sludge at the set sludge interface height at the end of the sedimentation process.

The calculation means outputs a sludge extraction command signal to the controller when "Yes", and the controller drives the sludge extraction means, whereby excess sludge in the batch reaction tank is automatically extracted. As a result, the amount of precipitated sludge in the batch reaction tank can be stably maintained near the above-mentioned set sludge interface height.

Therefore, according to the present invention, it is possible to efficiently manage the sludge in the batch reaction tank, the BOD-SS load, etc. with a very simple and economically advantageous device configuration. Clear liquid SS concentration, SVI,
This has the advantage that sludge treatment can be carried out with sufficiently accurate measurements of SRT and the like.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a batch-type sludge treatment control device showing one embodiment of the present invention, and FIG. 2 is a measurement operation diagram for each process showing the operation of FIG. 1. DESCRIPTION OF SYMBOLS 1... Batch type reaction tank, 4... Concentration detection means (concentration meter), 5... Concentration measuring section, 7... Calculation means (computation device), 11... Controller, 12... Sludge drawing means (pump) , H ₀ ...predetermined position.

Claims (1)

[Scope of Claims] 1. A batch-type reaction tank that receives inflow sewage and undergoes an aeration process, a precipitation process, a sludge extraction process, and a discharge process, and a sludge that is attached to this batch-type reaction tank and performs the extraction of the sludge. In the batch type activated sludge treatment apparatus, the batch type activated sludge treatment apparatus is provided with a predetermined position in the batch type reaction tank as a set sludge interface height, and has a concentration measuring unit disposed at a height position thereof, and during the aeration process, a concentration detection means for measuring the activated sludge concentration and detecting the presence or absence of sludge at the set sludge interface height at the end of the settling step; a calculation means that performs a comparison calculation with a set sludge concentration value, and when the actual concentration detected value exceeds the sludge concentration setting value by the calculation, a sludge extraction command signal based on an input signal from the calculation means is sent to the sludge A batch type activated sludge treatment apparatus comprising a controller that outputs to a drawing means and drives the sludge drawing means. 2 The activated sludge concentration measured by the concentration detection means, the sludge volume index based on the sludge extraction result, and the activated sludge cell average residence time are automatically calculated, displayed, or recorded by the calculation means. Batch-type activated sludge treatment equipment according to item 1.