JP2006263488A - Method and device of controlling amount of fed sludge solid in sludge dehydrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for controlling the amount of fed sludge solid in a sludge dehydrator which can cope with rapid concentration changes of various kinds of sludge to be dehydrated, different in properties with one kind of sludge concentration sensor, and exhibit the original performance of the dehydrator sufficiently without causing poor coagulation. <P>SOLUTION: Sludge is transferred from a sludge storage tank 2 into a sludge intermediary tank 3 by a sludge transfer pump 4. The concentration of sludge homogenized by a sludge agitating pump 7 in the sludge intermediary tank 3 is measured by a concentration sensor 8. The amount of sludge solid fed from the sludge intermediary tank 3 into a coagulation and mixing tank 10 by a sludge feed pump 9 is measured by a flowmeter 11. The liquid level fluctuation in the tank 10 is measured by a water level sensor 20. A frequency obtained based on the measured values by an operation part 16 of a control panel 15 is outputted into an inverter 17 for controlling the revolution number of the sludge feed pump 9 to control the revolution number of the pump, which feeds the sludge solid at a constant feed amount per hour to the sludge dehydrator 1 through the coagulation and mixing tank 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method and apparatus for adjusting the amount of sludge solids supplied in a sludge dewatering machine.

  As a means for adjusting the moisture content of the sludge, for example, as shown in FIGS. 1 and 2 of JP-A-2002-361299, the solid content concentration of the raw sludge is measured by a sludge concentration sensor provided in the mixing tank. The supply amount of the flocculant solution so that the ratio of the solid content of the sludge solid content and the solid content of the flocculant solution is determined with respect to the raw material sludge supplied within a predetermined time with reference to the measured solid content concentration, and When the operation time of the chemical liquid pump for the flocculant solution that supplies the flocculant solution is calculated, and when the flocculant solution is supplied to the raw material sludge and mixed and dehydrated based on the operation time, A predetermined amount of raw material sludge is supplied by the detection of the attached first liquid level sensor and measured with the sludge concentration sensor while stirring for a predetermined time so that the sludge concentration becomes uniform. When the supply amount of the flocculant solution is calculated based on the above settings and supplied to the mixing tank, and the mixed sludge mixed and stirred for a predetermined time with the predetermined amount of raw material sludge that has already been supplied can be supplied to the dehydrator The mixed sludge is supplied to the dehydrator and dehydration is started, and the liquid level of the mixed sludge stored in the mixing tank drops as the dehydration process proceeds. When it is confirmed by the detection of the second liquid level sensor that the mixed sludge has disappeared, the process from the supply of the mixed sludge to the disappearance of the dewatering process is considered as one batch process, and the predetermined target sludge is determined. A method and apparatus for adjusting the moisture content of sludge, in which the batch treatment is repeated until the treatment amount is reached, is performed (see Patent Document 1).

JP 2002-361299 A (page 3-4, FIG. 1-2)

  However, in the batch processing method in which the dehydrator of Patent Document 1 is operated intermittently, it is necessary to spend a lot of time for the dewatering of sludge or use a large capacity dehydrator with a large dewatering capacity. In paragraph 0008 of Document 1, the sludge to be dewatered is treated as "... feeding raw material sludge 1a made of various sludges generated from an external sewage treatment plant or agricultural settlement wastewater treatment facility into the mixing tank 2". It is described that it is a method and apparatus, and sludge concentration sensors are classified into ultrasonic type, near-infrared light type, microwave type, etc. when classified according to the measurement principle. Since the measurement accuracy varies depending on the difference in water content, color, and sludge shape, etc., it is a principle to use a sludge concentration sensor that is originally adapted to the properties of the sludge. Therefore, even if the above various sludge concentration sensors are used, in order to automatically determine which sludge concentration sensor is actually a true value, a huge amount of data processing is required and the apparatus itself is complicated. Therefore, the manufacturing cost increases. In addition, when trying to cope with one type of sludge concentration sensor, always monitor the change in the properties of the sludge to be dehydrated, and frequently perform the troublesome work of manual correction by trial and error according to the properties based on the history of many years. Therefore, there is a drawback that the original performance of the dehydrator cannot be exhibited unless much labor and maintenance costs are applied.

  Therefore, in the method of the present invention, in order to continuously perform the sludge dewatering treatment, the sludge is transferred from the sludge storage tank containing the sludge to be dehydrated by the sludge transfer pump and temporarily stored in the sludge relay tank. The concentration of the sludge that has been made uniform by the sludge agitation pump in the sludge relay tank is measured by the concentration sensor, and the measured value is sent to the control unit of the control panel to be recognized as the concentration value for control. The amount of sludge supplied to the coagulation / mixing tank is measured with a flow meter, and the measured value is sent to the control unit of the control panel for recognition. The polymer coagulant is injected into the coagulation / mixing tank and the sludge is mixed with the agitator. The control sludge solids supply amount per hour calculated based on the control concentration value and the supply amount recognized by the control unit of the control panel is input as a set value of the calculation unit in advance, and the control concentration Reverse from value The frequency of the sludge supply amount obtained in the calculation unit is output to the inverter that controls the rotation speed of the sludge supply pump, and the sludge solid matter per hour is controlled by controlling the rotation speed of the sludge supply pump based on the frequency In order to automatically adjust the sludge solids supply amount that is supplied to the sludge dewatering machine via the coagulation mixing tank so that the supply amount is constant and the dewatering capacity of the sludge dewatering machine is adjusted automatically, A signal measured by a water level sensor attached to the agglomeration and mixing tank to be supplied is sent to the calculation unit, and the control concentration value recognized by the calculation unit based on the detection signal is sent. The main feature is to perform correction processing and to control the operation of the sludge supply pump based on the corrected concentration value for control.

  Further, in the apparatus of the present invention, the above method is used to store a sludge storage tank containing sludge to be dewatered, a sludge relay tank for temporarily storing sludge supplied to the sludge dewatering machine, and a sludge in the sludge storage tank. A sludge transfer pump for transferring the sludge into the sludge relay tank, a drain pipe for draining the leaked sludge accumulated at the bottom of the sludge dehydrator into the sludge relay tank, and a drain for opening and closing the drain pipe A valve, a sludge agitation pump for making the sludge concentration in the sludge relay tank uniform, a concentration sensor for measuring the concentration of the sludge homogenized in the sludge relay tank, and agglomeration and mixing described later from within the sludge relay tank Accommodates sludge supply pump for supplying sludge to the tank, a flow meter for measuring the amount of sludge supplied by the sludge supply pump, and sludge supplied from the sludge relay tank to the sludge dehydrator Polymer flocculant A coagulation mixing tank for mixing, a polymer coagulant injection pump for injecting the polymer coagulant into the coagulation mixing tank, and a stirrer for mixing and stirring the polymer coagulant with sludge in the coagulation mixing tank And a control panel having a calculation unit for calculating the amount of sludge solids supplied to the sludge dehydrator based on the measured value by the concentration sensor and the flow meter, and a water level sensor for detecting the liquid level fluctuation in the tank The most important feature is that an inverter for controlling the rotation speed of the sludge supply pump is provided in response to the output signal from the arithmetic unit.

  According to the present invention, even when various types of sludges having different properties are to be dewatered and sludge dewatering treatment is performed continuously, only one type of sludge concentration sensor can be used with the sludge concentration sensor without using various sludge concentration sensors. Since the measured values are corrected as appropriate, the amount of sludge solids supplied from the coagulation mixing tank is automatically and optimally adjusted to the dewatering capacity of the sludge dewatering machine. In addition, there is an advantage that the original performance of the sludge dewatering machine can be sufficiently exhibited without increasing the manufacturing cost because the apparatus installation itself is not complicated without requiring complicated control.

  The sludge is transferred from the sludge storage tank containing the sludge to be dewatered by the sludge transfer pump, temporarily stored in the sludge relay tank, and the concentration of sludge homogenized by the sludge agitation pump in the sludge relay tank is set. The measured value is measured by the concentration sensor, and the measured value is sent to the control unit of the control panel to be recognized as the control concentration value.The amount of sludge supplied from the sludge relay tank to the coagulation mixing tank by the sludge supply pump is measured with a flow meter. Measure and send the measured value to the control unit of the control panel to recognize it, inject the polymer flocculant into the coagulation mixing tank, and mix and agitate with sludge using a stirrer. The sludge solids supply amount per hour calculated based on the concentration value and the supply amount is input in advance as the setting value of the calculation unit, and the frequency of the sludge supply amount obtained by the calculation unit by back calculation from the control concentration value is calculated. Sludge supply pump Output to the inverter that controls the number of revolutions, and control the number of revolutions of the sludge supply pump based on the frequency to supply the sludge solids supply to the sludge dehydrator via the coagulation mixing tank so that the amount of sludge solids supply per unit time is constant. In order to automatically adjust the amount of sludge solids supplied to the dewatering capacity of the sludge dewatering machine automatically and optimally, the liquid level fluctuation in the coagulation mixing tank for supplying sludge is attached to the tank. The signal measured by the water level sensor is sent to the calculation unit, the control concentration value recognized by the calculation unit is corrected based on the detection signal, and the sludge supply pump based on the corrected control concentration value To control the operation.

  FIG. 1 is a block diagram showing the configuration of the apparatus of the present invention, wherein 1 is a sludge dewatering machine for separating sludge into filtrate and dewatered cake, 2 is a sludge storage tank containing sludge to be dewatered, 3 A sludge relay tank for temporarily storing sludge supplied to the sludge dewatering machine 1, 4 is a sludge transfer pump for transferring sludge in the sludge storage tank 2 into the sludge relay tank 3, and 5 is a screen for removing contaminants. , 6 is an inorganic flocculant injection pump, which is used when the inorganic flocculant is injected into the sludge relay tank 3 in advance to make the sludge colloidal. 18P is a drain pipe for draining the leaked sludge accumulated at the bottom of the sludge dehydrator into the sludge relay tank 3, 18V is a drain valve for opening and closing the drain pipe 18P, and 7 is in the sludge relay tank 3. 1 is a concentration sensor for measuring the concentration of the sludge homogenized in the sludge relay tank 3, and 9 is in the coagulation and mixing tank 10 described later from the sludge relay tank 3. A sludge supply pump 11 is supplied to the sludge supply pump 9 and is a flow meter for measuring the supply amount of the sludge supplied by the sludge supply pump 9, and is provided in the discharge pipe of the sludge supply pump 9. 10 is a coagulation mixing tank for containing the sludge supplied from the sludge relay tank 3 to the sludge dewatering machine 1 and mixing the polymer coagulant, and 12 is for injecting the polymer coagulant into the coagulation mixing tank 10. A polymer flocculant injection pump, 13 is a dissolution unit panel, and 14 is a stirrer for mixing and stirring the polymer flocculant into sludge in the flocculent mixing tank 10, and measures the liquid level fluctuation in the flocculent mixing tank 10. A water level sensor 20 is provided. Reference numeral 15 denotes a control panel, which has a calculation unit 16 for calculating the amount of sludge solids supplied per hour to the sludge dewatering machine 1 based on the measured values by the concentration sensor 8, the flow meter 11 and the water level sensor 20. Yes. Reference numeral 17 denotes an inverter that receives the output signal from the calculation unit 16 and controls the rotational speed of the sludge supply pump 9.

  The sludge is transferred from the sludge storage tank 2 containing the sludge to be dehydrated by the sludge transfer pump 4 and temporarily stored in the small sludge relay tank 3 (if necessary, an inorganic flocculant is injected in advance to colloid In the sludge relay tank 3, the concentration of sludge homogenized by the sludge agitation pump 7 is measured by the concentration sensor 8, and the measured value is sent to the calculation unit 16 of the control panel 15 for control concentration. The amount of sludge supplied to the coagulation mixing tank 10 from the sludge relay tank 3 by the sludge supply pump 9 is measured by the flow meter 11 and the measured value is sent to the calculation unit 16 of the control panel 15. The polymer coagulant is injected into the coagulation mixing tank 10 and mixed with the sludge by the agitator 14, and the calculation unit 16 of the control panel 15 per unit time calculated based on the control concentration value and the supply amount. Sludge solid material While entering the amount in advance as a setting value of the arithmetic unit 16, the sludge solids supply amount is calculated by Equation 1 below.

  Then, the frequency of the sludge supply amount obtained by calculating backward from the control concentration value is output to the inverter 17 that controls the rotation speed of the sludge supply pump 9, and the rotation of the sludge supply pump 9 is performed based on the frequency. The sludge solids supplied to the sludge dewatering machine 1 via the coagulation mixing tank 10 so that the supply amount of sludge solids per hour becomes constant by controlling the number, and supplied to the dewatering capacity of the sludge dewatering machine 1 In order to automatically and optimally adjust the material supply amount, the fluctuation of the liquid level in the agglomeration mixing tank 10 for supplying sludge is sent to the arithmetic unit by a signal measured by the water level sensor 20 attached to the tank, Based on the detection signal, the control concentration value recognized by the calculation unit is corrected, and the sludge supply pump 9 is controlled to operate based on the corrected control concentration value. That is, when the recognized control concentration value is low, the sludge supply amount increases.When the recognized control concentration value is high, the sludge supply amount decreases. The amount of sludge solids supplied to the sludge dewatering machine 1 is kept constant as a variable.

  FIG. 2 is a flowchart showing the control of the inventive method according to another embodiment based on the adjustment method of the sludge solids supply amount in the sludge dewatering machine according to the first embodiment. The judgment time and the judgment start / stop count of the sludge supply pump at the judgment time are input as a set value, and the sludge supply is performed according to the liquid level fluctuation measured by the water level sensor provided in the coagulation mixing tank 10 based on the set value. The control concentration value recognized by the calculation unit is corrected according to the number of determination start / stop times of the sludge supply pump at the determination time, and the sludge is sludged based on the corrected control concentration value. By controlling the rotation speed of the supply pump, the amount of sludge solids supplied to the dewatering capacity of the sludge dewatering machine 1 is automatically and optimally adjusted.

  That is, the sludge solids supply amount actually contained in the sewage differs from the sludge solids supply amount with respect to the control concentration value measured and recognized by the sludge concentration sensor 8 due to the difference in sludge properties. When the amount of sludge solids contained is large, the sludge dewatering machine 1 for quantitative dewatering discharge used in the present invention has an excessive supply exceeding the dewatering function, so that the untreated overfeed overflowed from the sludge dewatering machine 1 The liquid level in the flocculation / mixing tank 10 frequently reaches the upper limit abnormal liquid level due to the sludge. Therefore, the sludge supply pump 9 is frequently started and stopped by the measurement signal of the water level sensor 20 attached to the flocculation / mixing tank 10, Since it is determined that the concentration value for control of current recognition is recognized to be lower than the actual sludge concentration by exceeding the number of times of determination start / stop of the sludge supply pump 9 in the determination time of the above setting, as an addition correction concentration value in advance The calculated value is added and corrected to the control concentration value for current recognition, and the corrected sludge supply amount is calculated from Equation 1 based on the newly recognized control concentration value after correction, The frequency of the sludge supply amount obtained in 16 is output to the inverter 17 that controls the rotation speed of the sludge supply pump 9, the rotation speed is lowered, the sludge supply volume to the sludge dehydrator 1 is reduced, and the determination The determination of the number of times of determination start / stop of the sludge supply pump in time is repeated, and the control concentration value recognized as appropriate is corrected.

  Conversely, when the amount of sludge solids actually contained in the sewage is small, the sludge supplied to the sludge dehydrator 1 is immediately dehydrated and discharged because of an excessive supply below the dewatering function of the sludge dewaterer 1. Therefore, since the liquid level in the flocculation mixing tank 10 does not reach the upper limit abnormal liquid level, the sludge supply pump 9 is continuously operated without stopping and starting, and the determination of the sludge supply pump 9 at the set determination time is performed. Since it is determined that the concentration value for control of current status recognition is recognized to be higher than the actual sludge concentration by lowering the number of stops, the value set in advance as the added correction concentration value is used as the control concentration value for current status recognition. Subtraction correction is performed, the corrected sludge supply amount is calculated from Equation 1 based on the newly recognized control concentration value after correction, and the frequency of the sludge supply amount obtained by the calculation unit 16 is supplied as sludge. Invar that controls the rotational speed of pump 9 The number of revolutions is increased by increasing the rotation speed and the amount of sludge supplied to the sludge dewatering machine 1 is increased, and the determination of the number of times of determination start / stop of the sludge supply pump in the determination time is repeated and recognized appropriately. The density value is corrected.

  In addition, when the sludge solids supply amount with respect to the control concentration value recognized as the sludge solids supply amount actually contained in the sewage is equivalent, the determination start / stop count of the sludge supply pump 9 in the determination time of the above setting is Since they are the same, the sludge supply pump 9 is operated at the current rotational speed without correcting the control-concentration value that is currently recognized. Therefore, the amount of sludge supplied to the sludge dewatering machine 1 is automatically and optimally adjusted in response to the recognized variation in the control concentration value so as to keep the amount of sludge solids supplied to the sludge dehydrator 1 constant.

  FIG. 3 is a flowchart showing the control of the inventive method according to another embodiment on the premise of the method for adjusting the sludge solids supply amount in the sludge dewatering machine of Embodiment 1, and the allowable liquid level range for determination in the coagulation mixing tank 10 And a signal measured by the water level sensor 20 provided in the tank 10 is sent to the calculation unit, and the calculation unit sets the liquid level in the coagulation mixing tank 10 based on the detection signal to the allowable liquid level range. The control concentration value recognized by the calculation unit 16 is corrected according to the determination result, and the sludge is based on the corrected control concentration value. By controlling the rotation speed of the supply pump, the amount of sludge solids supplied to the dewatering capacity of the sludge dewatering machine 1 is automatically and optimally adjusted.

  That is, the sludge solids supply amount actually contained in the sewage differs from the sludge solids supply amount with respect to the control concentration value measured and recognized by the sludge concentration sensor 8 due to the difference in sludge properties. When the amount of sludge solids contained is large, the sludge dewatering machine 1 for quantitative dewatering discharge used in the present invention has an excessive supply exceeding the dewatering function, so that the untreated overfeed overflowed from the sludge dewatering machine 1 The liquid level in the flocculation / mixing tank 10 reaches the upper limit abnormal liquid level due to the sludge, so that the control concentration value for the current recognition is recognized to be lower than the actual sludge concentration by the measurement signal of the water level sensor 20 provided in the flocculation / mixing tank 10. Therefore, the value previously set as the addition correction density value is added to the current density control density value and corrected, and the above formula is used based on the newly recognized control density value after correction. After correction from 1 The mud supply amount is calculated, and the frequency of the sludge supply amount obtained by the calculation unit 16 is output to the inverter 17 that controls the rotation speed of the sludge supply pump 9, and the rotation speed is lowered. The sludge supply amount is reduced, and the determination of the allowable liquid level range for determination is repeated in the agglomeration mixing tank 10 to correct the control concentration value recognized as appropriate.

  Conversely, when the amount of sludge solids actually contained in the sewage is small, the sludge supplied to the sludge dehydrator 1 is immediately dehydrated and discharged because of an excessive supply below the dewatering function of the sludge dewaterer 1. Therefore, the liquid level in the flocculation mixing tank 10 reaches the lower limit abnormal liquid level, and therefore, the control concentration value for the current recognition is recognized to be higher than the actual sludge concentration by the measurement signal of the water level sensor 20 provided in the flocculation mixing tank 10. Therefore, the value set in advance as the subtraction correction density value is subtracted and corrected to the current density control density value, and based on the newly recognized control density value after correction. The corrected sludge supply amount is calculated from Equation 1, the frequency of the sludge supply amount obtained by the calculation unit 16 is output to the inverter 17 that controls the rotation speed of the sludge supply pump 9, and the rotation speed is increased. Increased sludge supply volume to sludge dewatering machine 1 It is, to correct the allowable liquid level control concentration values determined are appropriately recognized repeated in the range for determining the mixing flocculation tank 10.

  In addition, when the sludge solid supply amount with respect to the control concentration value recognized as the sludge solid supply amount actually contained in the sewage is equivalent, the liquid level in the coagulation mixing tank 10 is within the allowable liquid level range, The sludge supply pump 9 is operated at the current rotational speed without correcting the control-concentration value that is currently recognized. Therefore, the sludge supply amount is automatically and optimally adjusted in response to the recognized variation in the control concentration sludge concentration, and the sludge solid matter supply amount to the sludge dewatering machine 1 is kept constant. .

It is a block diagram of this invention apparatus. It is a flowchart of the control by one Example of this invention method. It is a flowchart of control by another Example of this invention method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sludge dewatering machine 2 Sludge storage tank 3 Sludge relay tank 4 Sludge transfer pump 6 Inorganic flocculant injection pump 7 Sludge agitation pump 8 Concentration sensor 9 Sludge supply pump 10 Agglomeration mixing tank 11 Flowmeter 12 Polymer flocculant injection pump 14 Stirrer 15 Control panel 16 Arithmetic unit 17 Inverter 18P Drain pipe 18V Drain valve 20 Water level sensor

Claims (4)

  The sludge is transferred from the sludge storage tank containing the sludge to be dewatered by the sludge transfer pump, temporarily stored in the sludge relay tank, and the concentration of sludge homogenized by the sludge agitation pump in the sludge relay tank is set. The measured value is measured by the concentration sensor, and the measured value is sent to the control unit of the control panel to be recognized as the control concentration value.The amount of sludge supplied from the sludge relay tank to the coagulation mixing tank by the sludge supply pump is measured with a flow meter. Measure and send the measured value to the control unit of the control panel to recognize it, inject the polymer flocculant into the coagulation mixing tank, and mix and agitate with sludge using a stirrer. The sludge solids supply amount per hour calculated based on the concentration value and the supply amount is input in advance as the setting value of the calculation unit, and the frequency of the sludge supply amount obtained by the calculation unit by back calculation from the control concentration value is calculated. Sludge supply pump Output to the inverter that controls the number of revolutions, and control the number of revolutions of the sludge supply pump based on the frequency to supply the sludge solids supply to the sludge dehydrator via the coagulation mixing tank so that the amount of sludge solids supply per unit time is constant. In order to automatically adjust the amount of sludge solids supplied to the dewatering capacity of the sludge dewatering machine automatically and optimally, the liquid level fluctuation in the coagulation mixing tank for supplying sludge is attached to the tank. The signal measured by the water level sensor is sent to the calculation unit, the control concentration value recognized by the calculation unit is corrected based on the detection signal, and the sludge supply pump based on the corrected control concentration value A method for adjusting the amount of sludge solids supplied in a sludge dewatering machine, characterized in that the operation is controlled. The judgment time for judgment of the calculation part and the number of times of judgment start / stop of the sludge supply pump at the judgment time are inputted as a set value in the control panel in advance, and measured by a water level sensor provided in the coagulation mixing tank based on the set value The sludge supply pump is controlled to start and stop according to the liquid level fluctuation signal, and the control concentration value recognized by the calculation unit is corrected according to the number of times the sludge supply pump is determined and stopped at the determination time. By adjusting the rotation speed of the sludge supply pump based on the corrected concentration value for control, the amount of sludge solids supplied to the dewatering capacity of the sludge dewatering machine can be adjusted automatically and optimally. The method for adjusting the amount of sludge solids supplied in the sludge dewatering machine according to claim 1, wherein
  An allowable liquid level range for determination is set in the coagulation mixing tank, and a signal measured by a water level sensor attached in the tank is sent to the calculation unit. The liquid level is determined to be within the allowable liquid level range, above the upper limit, or below the lower limit, and the control concentration value recognized by the calculation unit is corrected according to the determination result, It is characterized by automatically adjusting the amount of sludge solids supplied to the dewatering capacity of the sludge dewatering machine by controlling the rotation speed of the sludge supply pump based on the control concentration value. The adjustment method of the sludge solid substance supply amount in the sludge dehydrator of Claim 1.   In a sludge dewatering machine for separating sludge into filtered water and dewatered cake, a sludge storage tank containing sludge to be dewatered, a sludge relay tank for temporarily storing sludge supplied to the sludge dewatering machine, and sludge Sludge transfer pump for transferring sludge in the storage tank into the sludge relay tank, drain pipe for draining the sludge accumulated at the bottom of the sludge dewatering machine into the sludge relay tank, and opening and closing the drain pipe A drain valve, a sludge agitation pump for homogenizing the sludge concentration in the sludge relay tank, a concentration sensor for measuring the concentration of the sludge homogenized in the sludge relay tank, and the sludge relay tank To the sludge supply pump for supplying sludge to the coagulation mixing tank, a flow meter for measuring the amount of sludge supplied by the sludge supply pump, and a sludge relay tank for supply to the sludge dehydrator Sludge A coagulation / mixing tank for mixing the polymer coagulant, a polymer coagulant injection pump for injecting the polymer coagulant into the coagulation / mixing tank, and a polymer coagulant in the coagulation / mixing tank. Calculate the amount of sludge solids supplied per hour to the sludge dehydrator based on the agitator for mixing and stirring the sludge, the water level sensor for detecting fluctuations in the liquid level in the coagulation mixing tank, and the concentration sensor and flow meter. And a control panel having a calculation unit for performing the operation, and an inverter for controlling the rotation speed of the sludge supply pump in response to an output signal from the calculation unit, and a sludge solids supply amount adjusting device in a sludge dehydrator .

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