JPS5944120B2 - Sludge concentrator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention is applicable to sewage treatment, human waste treatment, etc.
A sludge concentrator for concentrating organic sludge generated in water treatment processes, which maintains the solid content recovery rate of the sludge at a constant value at all times and provides economical operational control of the concentrator. This is what we are trying to provide.

Fig. 1 is a piping diagram showing a conventional sludge concentrator of this type, in which 1 is a variable flow rate pump, 2 is a sludge concentrator, 2a is a sludge supply port, 2b is a concentrated sludge discharge port, and 2c is a sludge concentrator.
3 is a separated liquid discharge port, 3 is the treated sludge stored in the storage tank 4, 5 is the concentrated sludge stored in the concentrated sludge storage tank 6, 7 is stored in the separated liquid storage tank 8, and the concentrated sludge storage tank 6 is This is a separated liquid that is separated from the concentrated sludge 5 inside.

Since the conventional sludge concentrator is configured as described above, when the variable flow rate pump 1 feeds the sludge 3 to be treated in the storage tank 4 into the sludge concentrator 2 having a predetermined volume, the concentrated sludge 5 is automatically and separation liquid 7,
The concentrated sludge is discharged from the non-outlet 2b and the separated liquid outlet 2c to the concentrated sludge storage tank 6 and the separated liquid storage tank 8, respectively, and is configured to be stably and continuously processed. The respective amounts and concentrations of the sludge to be treated 3, the concentrated sludge 5, and the separated liquid 7 are as follows:
Appropriate conditions exist according to the characteristics of the sludge thickener 2.

Conventionally, in order to grasp this condition, various tests such as changing the flow rate have been carried out, and sampling sludge collected from the sludge supply port 2a to be treated, the concentrated sludge discharge port 2b, and the separated liquid discharge port 2c each time has been conducted. The concentration is measured using, for example, an infrared moisture meter or a solid content meter, and the recovery rate N is determined by hand calculation using the following formula.

where, In the case of a machine, if the results of these calculations are plotted, for example, on graph paper as the recovery rate versus the amount of sludge supplied, a characteristic curve as shown in FIG. 2 will be obtained.

In other words, in the case of the above-mentioned centrifugal concentrator, there are other factors that affect the recovery rate, such as the centrifugal effect G, the rotational speed difference between the screw and the bowl, the dam level, etc., and all of these factors are concentrated on the flow rate. Although it is possible to obtain the desired recovery rate, in order to achieve the most economical sludge concentration, the three adjustment factors described above must be set first, and then the final sludge feed liquid In addition to conducting tests to set the amount, in order to ensure stable continuous operation, based on the data obtained during the test run,
The method used is to determine the most appropriate amount of sludge to be supplied and set it for continuous operation of sludge concentration, but this conventional method does not make the equipment economical. This method is easy to operate and is excellent when the properties of the sludge to be treated always remain unchanged; however, as mentioned above, even if the properties of the sludge to be treated are always constant, It is difficult to maintain a constant sludge concentration no matter what type of equipment is used, and it is normal for the concentration difference to vary several times between the start and end of thickening. In addition, when the properties of sludge change minutely depending on the climate and season, such as sludge from a water treatment plant whose water source is dam water or lake water, delicate adjustments that rely on the skill of the operator of the thickening device are required. In this way, it is not only necessary to set the amount of liquid to be supplied for the sludge to be treated, but also to allow for fluctuations.
Even if the operating means is set to fine, it still depends on the operator's sense, so if there are many fine particle components in the sludge to be treated, solids may pass through to the separation liquid side without being separated. In closed-loop systems in which the separated liquid is returned to the raw water, there are problems such as "carry-over" occurring in the sedimentation tank.

Furthermore, although we have not heard of any specific problems with the river discharge method, if the recovery rate falls below the planned value, it has the disadvantage of causing pollution of downstream rivers.

As mentioned above, in order to carry out careful thickening operation while taking into consideration all possible problems, it is necessary to operate the sludge thickener with a large margin for fluctuations in sludge concentration and sludge properties, which makes the sludge thickener uneconomical. You will be required to drive.

This invention has been made with attention to this point, and aims to provide a sludge concentrator that can always maintain a constant sludge recovery rate even when there are fluctuations in sludge concentration and sludge properties. be.

That is, FIG. 3 is a piping diagram showing the principle of this invention.
2 is a variable flow rate pump, 2 is a treated sludge supply port 2a, a concentrated sludge discharge port 2b, and a separated liquid discharge port 2.
10a, 10c are flow rate measuring devices, 11a, 11c are sludge concentration measuring devices, 12
internally includes a constant setter 12a, a data reading circuit 12b, arithmetic circuits 12c, 12h, and comparison/judgment circuits 12d, 1.
2e.

12j, adjustment circuits 12f and 12g, a display circuit 12, and a control device 121.

Before explaining the overall operation of the sludge concentrator configured as above, first, the formulas of the arithmetic circuits 12c and 12h will be explained.

That is, the recovery rate N in the conventional formula is calculated from the above formula [1], which is obtained from the sampling sludge collected from the treated sludge supply port 2a, the concentrated sludge discharge port 2b, and the separated liquid discharge port 2c of the sludge concentrator 2. However, when controlling online, this [υ formula is inconvenient, so a formula that uses the flow rates and concentrations on the supply liquid side and the separated liquid side, which are relatively easy to measure, may be used.

This is applied to one of the arithmetic circuits 12c.

In other words, the recovery rate N is, where A is the amount of liquid supplied (m''/Hr), C is the amount of separated liquid (m''/Hr), X is the concentration of the sludge to be treated 3 (%), and 2 is the concentration of the separated liquid 7 ( %) Next, the other arithmetic circuit 12h calculates the amount of concentrated sludge using the following formula.

D-AX-cz ・・・・・・・・・・・・(kawa and,
Needless to say, it also has a function to integrate this value every moment.

Next, the overall operation of the above-mentioned sludge concentrator will be explained.

That is, when the variable flow rate pump 1 and the sludge concentrator 2 are operated, the sludge is continuously treated, and the sludge is continuously supplied to the treated sludge supply port 2a, the concentrated sludge discharge port 2b, and the separated liquid discharge port 2c. When the sludge to be treated, the concentrated sludge, and the separated liquid flow through the flow rate measuring device 10a.

10c and a sludge concentration measuring device 11a.

11c detects the flow rate and concentration of the sludge to be treated and the flow rate and concentration of the separation liquid, respectively.

On the other hand, the control device 12 controls each of the measuring devices 10a, 10c.
, 11a.

11c is read into the data reading circuit 12b, and the target recovery rate No. is also read from the built-in constant setting device 12a.
2 to the allowable deviation value K and the lower limit of the amount of concentrated sludge.
Next, the value is calculated by the arithmetic circuits 12c and 12h, and the current recovery rate N and concentrated sludge weight are calculated.

Then, the calculation result is compared and judged by the circuit 12a+12
The allowable deviation value K of the recovery rate and the concentrated sludge are determined by j.
.

If it is rYEsJ, it is left as is, and if it is "NO", the former is sent to one of the comparison/judgment circuits 12e, and the latter is configured to output an indication of a decrease in capacity. .

Therefore, in the comparison/judgment circuit 12e, the following is true.

Determine whether the result is "dog" or "small" with respect to the target recovery rate No. If it is "dog", increase the flow rate and increase the processing amount to increase the processing amount, and if it is "small" It is configured to control so as to reduce the flow rate and improve the recovery rate N.

Next, one embodiment of the present invention will be described.

In addition, the part shown by the solid line in FIG. 3 shows one embodiment of the present invention.

When (ie, Arc) is considered in the above equation (2), the following simplified equation holds true.

In this case, since A>C, N'<N and N'
When used for comparison with a reference value when maintaining the lower limit of the recovery rate, the error is always on the side of exceeding the target and there is no problem.

That is, the recovery rate can be calculated as a guideline even without a flow meter, and the recovery rate can be maintained and controlled.

That is, when the variable flow rate pump 1 and the sludge concentrator 2 are operated, the sludge is continuously treated, and the sludge is continuously supplied to the treated sludge supply port 2a, the concentrated sludge discharge port 2b, and the separated liquid discharge port 2c. When the sludge to be treated, the concentrated sludge, and the separated liquid flow, the sludge concentration measuring devices 11a and 11c detect the concentration of the sludge to be treated and the concentration of the separated liquid, respectively.

On the other hand, the control device 12 reads the detected amounts of the measuring devices 11a and 11c into the data reading circuit 12b, and also reads the target recovery rate No. and its allowable deviation value K from the built-in constant setting device 12a. , the value is calculated by the arithmetic circuit 12c, and the current collection rate N is calculated.

Then, the comparison and determination circuit 121i compares and separates this calculation result into an allowable deviation value of the recovery rate.
It is designed to output to e.

Therefore, in the comparison and determination circuit 12e, it is determined whether the result is "dog" with respect to the target recovery rate No., and if it is "dog", the flow rate is increased to increase the processing amount,
Moreover, if it is "small", the control is performed to reduce the flow rate and improve the recovery rate N.

As described above, according to the present invention, since the sludge concentration measuring device 11a, 11c and the control device 12 have a relatively simple configuration to form a sludge concentration device +5, the recovery rate in sludge concentration is increased. is always maintained at a constant level, which not only contributes to the safe operation of various devices placed upstream and downstream of the sludge treatment facility, but also contributes to the economical operation of the sludge thickening equipment, and also ensures that the sludge recovery rate does not decrease. Since it can be grasped, it has an excellent effect of allowing the timing of maintenance of the sludge thickening device to be grasped accurately.

[Brief explanation of the drawing]

Fig. 1 is a piping diagram showing a conventional sludge concentrator, Fig. 2 is a characteristic curve of the recovery rate of sludge solids versus the amount of sludge supplied, and Fig. 3 is a piping diagram showing the principle of the present invention. . In the drawing, 1 is a variable flow rate pump, 2 is a sludge thickener, 2
a is a sludge supply port to be treated, 2c is a separated liquid discharge port, 10
a, 10c is a flow rate measuring device, and 11a. 11c is a sludge concentration measuring device, 12 is a control device, 12
a is a constant setter, 12b is a data reading circuit, 12c, 1
2h is an arithmetic circuit, 12d, 12e. 12j is a comparison judgment circuit, 12f and 12g are adjustment circuits, 1
2, 121 is a display circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A concentrator for concentrating sludge generated in a water treatment process such as sewage treatment or human waste treatment, and separating it into concentrated sludge and separated liquid. A sludge concentration measuring device that measures the concentration (X%) of the sludge to be treated that is supplied to the thickener, and a sludge concentration device that is installed on the separated liquid outlet side of the thickener and measures the sludge concentration (7%) of the separated liquid. A measuring device, a calculation device that calculates the sludge recovery rate N by deriving the sludge concentration (X, Z) from both of the sludge concentration measurement devices into an equation, and a sludge recovery rate N derived from this calculation device and a reference sludge recovery rate. Compare with No>
A sludge concentrator comprising a regulating device that increases the treated sludge flowing into the thickener if No, and decreases the treated sludge flowing into the thickener if N<No.