JP7199210B2 - Control device, solid-liquid separation method, computer program, and solid-liquid separation system - Google Patents

Description

TECHNICAL FIELD Embodiments of the present invention relate to control devices, solid-liquid separation methods , computer programs , and solid-liquid separation systems .

Solid-liquid separation treatment is one of methods for purifying water to be treated such as waste water and sludge. In wastewater treatment, solid-liquid separation is performed as a pretreatment, and the separated solids and wastewater are treated by appropriate methods, thereby reducing treatment costs. In sludge treatment, solid-liquid separation treatment is performed as dehydration treatment of sludge, and by reducing the volume of sludge, the cost required for transportation and disposal can be reduced. In such a solid-liquid separation process, a polymer flocculant may be injected into the water to be treated in order to improve solid-liquid separation performance. The polymer flocculant has the effect of flocculating solids in the water to be treated, and has the effect of increasing the sedimentation property of the solids, thus contributing to the improvement of solid-liquid separation performance.

On the other hand, if the injection amount of the polymer flocculant is insufficient, the solid-liquid separation performance will decrease, and if the injection amount is too large, a large amount of the polymer flocculant will remain in the water to be treated, resulting in deterioration of the treated water. Therefore, the injection amount of the polymer flocculant must be appropriately adjusted according to the fluctuation of the amount of solid matter in the water to be treated. In general, setting the injection rate of the polymer flocculant is performed by selecting one that has shown good solid-liquid separation performance in a simulated solid-liquid separation test in a laboratory, and manually setting the selected injection rate. ing. However, since the concentration of solids in the water to be treated may fluctuate, such a method of setting the injection rate may not be able to cope with fluctuations in the concentration of solids.

JP 2010-137115 A JP 2013-223846 A JP-A-11-57731

The problem to be solved by the present invention is to provide a control device, a solid-liquid separation method , a computer program , and a solid-liquid separation system that can suppress deterioration in solid-liquid separation performance of water to be treated.

The control device of the embodiment comprises a dissolution tank for mixing a polymer flocculant and dissolution water to prepare a polymer solution; and a solid-liquid separator for separating the water to be treated in which the solids have aggregated into solids and water. The control device has a control unit. The control unit controls the injection amount of the polymer solution into the water to be treated based on the concentration of the polymer flocculant remaining in the separated water, which is the water to be treated from which solid matter has been separated by the solid-liquid separator. .

The figure which shows the structural example of the conventional solid-liquid separation system. The figure which shows the structural example of the solid-liquid separation system of 1st Embodiment. FIG. 2 is a diagram showing a specific example of the functional configuration of a control device according to the first embodiment; The figure which shows the structural example of the solid-liquid separation system of 2nd Embodiment. The figure which shows the specific example of the functional structure of the control apparatus in 2nd Embodiment. The figure which shows the structural example of the solid-liquid separation system of 3rd Embodiment. The figure which shows the structural example of the solid-liquid separation system of 4th Embodiment. The figure which shows the structural example of the solid-liquid separation system of 5th Embodiment. The figure which shows the specific example of the functional structure of the control apparatus in 5th Embodiment. FIG. 5 is a diagram for explaining new knowledge obtained with respect to the solid-liquid separation systems of the first to fifth embodiments;

Hereinafter, a control device, a solid-liquid separation method , a computer program , and a solid-liquid separation system according to embodiments will be described with reference to the drawings.

(outline)
FIG. 1 is a diagram showing a configuration example of a conventional solid-liquid separation system. The solid-liquid separation system 90 includes a dissolution tank 91 , a first stirrer 92 , a polymer solution injection pump 93 , a coagulation tank 94 , a second stirrer 95 and a solid-liquid separation device 96 . The dissolution tank 91 dissolves the granular polymer flocculant in water (hereinafter referred to as "dissolution water") as a solvent to prepare an aqueous solution of the polymer flocculant (hereinafter referred to as "polymer solution"). water tank. The first stirrer 92 is a device that stirs the polymer flocculant and the dissolved water introduced into the dissolving tank 91 . The polymer solution injection pump 93 is a device for injecting the polymer solution prepared in the dissolving tank 91 into the aggregation tank 94 . The coagulation tank 94 is a tank for mixing the polymer solution and the water to be treated to coagulate solids in the water to be treated. The second stirrer 95 is a device for stirring to mix the polymer solution and the water to be treated. The solid-liquid separation device 96 is a device that separates the water to be treated in which the solids have aggregated into solids and water.

Here, the polymer solution injection pump 93 is configured to operate at an injection rate determined based on the results of a simulation test of solid-liquid separation conducted in laboratory L (hereinafter referred to as "set injection rate"). be done. Basically, the set injection rate is determined based on the test results showing good solid-liquid separation performance. The injection rate is not always optimal at the time of setting. If the set injection rate is smaller than the optimum injection rate, the solid-liquid separation performance is lowered, and the water to be treated cannot be separated into desired properties of water and solids. Also, if the injection rate is higher than the optimum injection rate, the solid-liquid separation performance is also lowered. Moreover, since the injection amount of the polymer flocculant increases, the chemical cost also increases. Furthermore, a large amount of the polymer flocculant will remain in the water, and there is concern that the quality of the treated water will deteriorate. For these reasons, conventionally, there have been cases where the injection amount of the polymer flocculant was not necessarily an appropriate amount.

(First embodiment)
FIG. 2 is a diagram showing a configuration example of the solid-liquid separation system of the first embodiment. A solid-liquid separation system 100 of the first embodiment includes a dissolution tank 1 , a polymer solution injection pump 2 , a coagulation tank 3 , a solid-liquid separator 4 , a first water tank 41 and a controller 5 . The dissolution tank 1 dissolves a granular polymer flocculant in water (hereinafter referred to as "dissolution water") as a solvent to prepare an aqueous solution of the polymer flocculant (hereinafter referred to as "polymer solution"). water tank. The dissolving tank 1 is equipped with a first stirrer 11 for stirring the polymer solution.

The polymer solution injection pump 2 is a device for injecting the polymer solution prepared in the dissolving tank 1 into the aggregation tank 3 . Polymer solution injection pump 2 is communicably connected to controller 5 . The polymer solution injection pump 2 injects the polymer solution based on the injection rate notified from the controller 5 .

The coagulation tank 3 is a tank for mixing the polymer solution injected by the polymer solution injection pump 2 and the water to be treated to coagulate solids in the water to be treated. The aggregation tank 3 is equipped with a second stirrer 31 for stirring the mixed water of the polymer solution and the water to be treated.

The solid-liquid separation device 4 is a device that separates the water to be treated (mixed water) in which the solids are aggregated by injecting the polymer solution into solids and water. The first water tank 41 is a water tank for storing water (hereinafter referred to as “separated water”) from which the solid matter is separated by the solid-liquid separator 4 . The first water tank 41 is equipped with a water quality meter 42 that measures an index value of the concentration of the polymer flocculant remaining in the separated water (hereinafter referred to as "residual polymer concentration"). For example, the water quality meter 42 measures the UV-VIS (Ultra Violet-Visible) absorbance of the polymer solution. The water quality meter 42 is communicably connected to the control device 5 and transmits measurement data to the control device 5 .

The control device 5 has a function of adjusting the injection amount of the polymer solution injected into the coagulation tank 3 according to the residual polymer concentration of the separated water. Specifically, the control device 5 determines the injection rate of the polymer solution injection pump 2 based on the measurement data of the water quality meter 42 .

FIG. 3 is a diagram illustrating a specific example of the functional configuration of the control device according to the first embodiment; The control device 5 in the first embodiment includes a CPU (Central Processing Unit), a memory, an auxiliary storage device, and the like connected via a bus, and executes programs. The control device 5 functions as a device including a communication section 51, a storage section 52, a measurement data acquisition section 53, and a first injection rate control section 54 by executing a program. All or part of each function of the control device 5 may be implemented using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). The program may be recorded on a computer-readable recording medium. Computer-readable recording media include portable media such as flexible disks, magneto-optical disks, ROMs and CD-ROMs, and storage devices such as hard disks incorporated in computer systems. The program may be transmitted via telecommunication lines.

A communication unit 51 is a communication interface. The communication unit 51 may be a wired communication interface or a wireless communication interface. The communication unit 51 is communicably connected to the water quality meter 42 and the polymer solution injection pump 2 .

The storage unit 52 is configured using a storage device such as a magnetic hard disk device or a semiconductor storage device. The storage unit 52 stores measurement data of the water quality meter 42 . The storage unit 52 stores in advance data indicating the correlation between the index value of the residual polymer concentration and the residual polymer concentration (hereinafter referred to as "correlation data").

The measurement data acquisition unit 53 acquires measurement data from the water quality meter 42 via the communication unit 51 . The measurement data acquisition unit 53 stores the acquired measurement data in the storage unit 52 .

The first injection rate control section 54 has a function of controlling the injection rate of the polymer solution injection pump 2 . Specifically, the first injection rate controller 54 corrects the injection rate of the polymer solution injection pump 2 determined by a solid-liquid separation test or the like in a laboratory, according to the residual polymer concentration of the separated water. The injection rate to be corrected based on the solid concentration of the water to be treated may be determined by the first injection rate control section 54 or may be determined by another function (not shown).

More specifically, the correlation data generated by the following procedure example is recorded in the storage unit 52 in advance.
[Procedure 1] A plurality of patterns of polymer solutions having different mixing ratios of polymer flocculant and pure water are prepared.
[Procedure 2] For each pattern of the polymer solution prepared in Procedure 1, the index value of the polymer concentration is measured. The index value of the residual polymer concentration in this embodiment is the UV-VIS (Ultra Violet-Visible) absorbance of the polymer solution, which is measured using UV-visible light having a wavelength of 190 nm to 240 nm. Therefore, in Procedure 2, UV-visible light having the same wavelength is used to measure the polymer concentration of each pattern.
[Procedure 3] The index value of the polymer concentration measured in Procedure 2 and the polymer concentration calculated from the mixture ratio are associated with each pattern.

The first injection rate control unit 54 controls the first water tank based on the correlation data thus generated and the measurement data of the residual polymer concentration index value acquired during the solid-liquid separation process. Estimate the residual macromolecule concentration in the separated water stored in 41 .

For example, if the residual polymer concentration in the separated water is 100 mg/L or more, the first injection rate control unit 54 determines that the injection rate is higher than the optimum value, and excess polymer flocculant remains in the separated water. Then, the injection rate before correction is reduced by 0.1%, for example.

In the solid-liquid separation system 100 of the first embodiment configured as described above, the injection amount of the polymer flocculant into the water to be treated is corrected according to the fluctuation in the concentration of the polymer flocculant that has flowed out to the separated water. be. As a result, the injection rate of the polymer flocculant determined by a solid-liquid separation test in a laboratory can be adjusted to a more appropriate value according to the excess or deficiency of the injection amount, and solid-liquid separation of the water to be treated can be performed. It becomes possible to suppress deterioration in performance.

(Second embodiment)
FIG. 4 is a diagram showing a configuration example of the solid-liquid separation system of the second embodiment. The solid-liquid separation system 100a of the second embodiment differs from the solid-liquid separation system 100 of the first embodiment in that it includes a water quality meter 42a in place of the water quality meter 42 and a control device 5a in place of the control device 5. different from Since other configurations are the same as those of the first embodiment, the same configurations in FIG. 4 are denoted by the same reference numerals as those in FIG.

The water quality meter 42a is the first in that it measures the indicator values of the COD (Chemical Oxygen Demand) concentration and the SS (Suspended Solid) concentration in addition to the residual polymer concentration. is different from the water quality meter 42 of the embodiment. Specifically, the COD concentration index value is the UV-VIS absorbance measured using UV-visible light having a wavelength of about 254 nm. Also, the SS concentration index value is the UV-VIS absorbance measured using UV-visible light having a wavelength of about 546 nm.

FIG. 5 is a diagram showing a specific example of the functional configuration of the control device according to the second embodiment. The control device 5a in the second embodiment is similar to the first embodiment in that it includes a storage unit 52a instead of the storage unit 52 and includes a first injection rate control unit 54a instead of the first injection rate control unit 54. is different from the control device 5 in . Since other configurations are the same as those of the first embodiment, the same configurations in FIG. 5 are denoted by the same reference numerals as in FIG.

The storage unit 52a differs from the storage unit 52 in the first embodiment in that the second correlation data and the third correlation data are stored in advance in addition to the correlation data in the first embodiment. Hereinafter, the correlation data in the first embodiment will be referred to as the first correlation data and distinguished from the second correlation data and the third correlation data. The second correlation data is data indicating the correlation between the COD concentration index value (UV-VIS absorbance at 254 nm wavelength) of separated water and the COD concentration. The third correlation data is data showing the correlation between the SS concentration index value (UV-VIS absorbance at 546 nm wavelength) of the separated water and the SS concentration. The second correlation data and the third correlation data can also be generated by the same procedure as the first correlation data.

The first injection rate control unit 54a has a function of controlling the injection rate of the polymer solution injection pump 2, and is the same as the first injection rate control unit 54 in the first embodiment. It differs from the injection rate control section in the first embodiment in that the injection rate is controlled based on the COD concentration and the SS concentration in addition to the concentration.

When measuring the residual polymer concentration in the separated water by measuring the UV-VIS absorbance at a wavelength of 190 nm to 240 nm, it becomes difficult to accurately estimate the residual polymer concentration if the separated water has too high a turbidity. In such a case, there is a possibility that the polymer solution injection pump 2 cannot be controlled at an appropriate injection rate. Therefore, the first injection rate control unit 54a in the present embodiment uses the SS concentration or COD concentration of the separated water to determine the estimation accuracy of the residual polymer concentration.

Here, it is generally known that the UV-VIS absorbance at a wavelength of 254 nm has a high correlation with the SS concentration, and the UV-VIS absorbance at a wavelength of 546 nm has a high correlation with the COD concentration. On the other hand, if the SS concentration is too high, it becomes difficult to measure the absorbance that has a high correlation with the COD concentration, and if the COD concentration is too high, it becomes difficult to measure the absorbance that has a high correlation with the residual polymer concentration. Therefore, for example, the first injection rate control unit 54a determines the estimation accuracy of the residual polymer concentration by determining whether or not the estimated value of the SS concentration or the COD concentration is within a predetermined range.

In this case, for example, the first injection rate control unit 54a determines that the estimated residual polymer concentration has sufficient accuracy when both the SS concentration and the COD concentration are within respective predetermined ranges. Then judge.

In addition, the first injection rate control unit 54a may report information indicating the determination result (hereinafter referred to as "accuracy information") by displaying it on a display device or the like. By being notified of such accuracy information, for example, the operator of the solid-liquid separation system 100a performs work to reduce the turbidity of the separated water (for example, work such as diluting the separated water with water). It is possible to suppress a decrease in the accuracy of estimating the polymer concentration.

According to the solid-liquid separation system 100a of the second embodiment configured in this way, the residual polymer concentration in the separated water can be measured with higher accuracy, so that the deterioration of the solid-liquid separation performance of the water to be treated can be prevented. can be suppressed.

(Third embodiment)
FIG. 6 is a diagram showing a configuration example of a solid-liquid separation system according to the third embodiment. A solid-liquid separation system 100b of the third embodiment stores water (hereinafter referred to as "filtered water") from which solid substances remaining in the separated water are separated by the filtering device 6 for filtering the separated water and the filtering device 6. The solid-liquid separation system 100 differs from the solid-liquid separation system 100 of the first embodiment in that it further includes a second water tank 61 and that the second water tank 61 is provided with a water quality meter 42 instead of the first water tank 41 . Since other configurations are the same as those of the first embodiment, in FIG. 6, similar configurations are denoted by the same reference numerals as in FIG. Note that the filter medium of the filtering device 6 is not limited to a specific one, and may be of any type as long as it can separate solids in the separated water.

According to the solid-liquid separation system 100b of the third embodiment configured in this way, a certain amount of solid matter is separated from the separated water before the index value of the residual polymer concentration is measured, and the residual height can be obtained with higher accuracy. Since the molecular concentration is measured, it is possible to suppress deterioration of solid-liquid separation performance of the water to be treated.

Note that in the solid-liquid separation system 100b of the third embodiment, the concentration of residual polymers in filtered water can be estimated using the absorbance of ultraviolet-visible light, the COD concentration, and the SS concentration, as in the second embodiment. good. Also, in this case, the first injection rate control unit 54 may determine the estimation accuracy of the residual polymer concentration using the SS concentration or COD concentration of the filtered water, as in the second embodiment.

(Fourth embodiment)
FIG. 7 is a diagram showing a configuration example of a solid-liquid separation system according to the fourth embodiment. The solid-liquid separation system 100c of the fourth embodiment includes a third water storage tank 43 for storing water for diluting the separated water (hereinafter referred to as "dilution water"), and separated water diluted with the dilution water (hereinafter referred to as " The second embodiment is characterized in that it further includes a fourth water tank 44 that stores diluted and separated water, and that the fourth water tank 44 is equipped with a water quality meter 42 instead of the first water tank 41. It differs from the solid-liquid separation system 100a. In this case, for example, the flow rate of the dilution water is adjusted by the operator of the solid-liquid separation system 100a based on the accuracy information notified by the controller 5a. Since other configurations are the same as those of the fourth embodiment, the same configurations in FIG. 7 are denoted by the same reference numerals as in FIG.

According to the solid-liquid separation system 100c of the fourth embodiment configured as described above, the separated water is diluted to some extent before the index value of the residual polymer concentration is measured, so that the residual polymer concentration can be measured with higher accuracy. Therefore, it is possible to suppress the deterioration of the solid-liquid separation performance of the water to be treated.

In addition, in the solid-liquid separation system 100c of the fourth embodiment, the residual polymer concentration in the diluted separated water may be estimated based on the absorbance of ultraviolet-visible light, as in the first embodiment. Moreover, the solid-liquid separation system 100c of the fourth embodiment may be provided with the filtering device 6 similar to that of the third embodiment between the first water tank 41 and the fourth water tank 44 .

(Fifth embodiment)
FIG. 8 is a diagram showing a configuration example of a solid-liquid separation system according to the fifth embodiment. The solid-liquid separation system 100d of the fifth embodiment has a dilution water injection pump 7 for injecting dilution water into the separated water, and a control device 5b instead of the control device 5a. It differs from the solid-liquid separation system 100c. The control device 5b has the same function as the control device 5a of the third embodiment, in addition to the function of controlling the injection rate of the dilution water injection pump 7 based on the measurement data. Different from 5a. Since other configurations are the same as those of the fourth embodiment, the same configurations in FIG. 8 are denoted by the same reference numerals as in FIG.

FIG. 9 is a diagram showing a specific example of the functional configuration of the control device according to the fifth embodiment. The control device 5b in the fifth embodiment differs from the control device 5a in the fourth embodiment in that a second injection rate control section 55 is further provided. Since other configurations are the same as those of the fourth embodiment, the same configurations in FIG. 9 are denoted by the same reference numerals as those in FIG. 5, and descriptions thereof are omitted.

The second injection rate control unit 55 has a function of controlling the injection rate of the dilution water injection pump 7 based on the measurement data of the water quality meter 42a. For example, the control device 5b pre-stores in the storage unit 52a dilution data indicating the correspondence relationship between the residual polymer concentration, COD concentration or SS concentration of the diluted and separated water and the injection rate of the diluted water. The control unit 55 determines the dilution water injection rate based on the dilution data and the measurement data, and notifies the dilution water injection pump 7 of it.

According to the solid-liquid separation system 100d of the fifth embodiment configured as described above, the diluted water is injected into the separated water at an injection rate corresponding to the residual polymer concentration, COD concentration, or SS concentration of the diluted separated water. Therefore, the diluted separated water is adjusted to a concentration suitable for measuring the residual polymer concentration, COD concentration or SS concentration. As a result, the diluted and separated water is appropriately diluted and the residual polymer concentration can be measured with higher accuracy, so that deterioration of the solid-liquid separation performance of the water to be treated can be suppressed.

In addition, in the solid-liquid separation system 100d of the fifth embodiment, the residual polymer concentration in the diluted separated water may be estimated based on the absorbance of ultraviolet-visible light, as in the first embodiment. Moreover, the solid-liquid separation system 100d of the fifth embodiment may be provided with the filtering device 6 similar to that of the third embodiment between the first water tank 41 and the fourth water tank 44 .

FIG. 10 is a diagram for explaining new knowledge obtained regarding the solid-liquid separation systems of the first to fifth embodiments. FIG. 10 shows an example of the correspondence obtained with respect to the concentration of the polymer solution (polymer concentration), the wavelength of the UV-visible light used to measure the concentration of the polymer solution, the control sensitivity, and the correlation strength. there is The control sensitivity is an index showing the stability of control using the correlation between each polymer concentration and the absorbance obtained by ultraviolet-visible light of each wavelength. The slope of the straight line representing is used. The correlation strength is an index representing the strength of the correlation between the polymer concentration and the absorbance, and the square value of the correlation coefficient R is used here.

FIG. 10 shows that in a wide concentration range (the entire figure), the polymer concentration could be measured with high accuracy by using ultraviolet-visible light with a wavelength of 220 nm. This indicates that the use of UV-visible light with a wavelength of 5 nm enabled local measurement of the polymer concentration with higher accuracy. FIG. 10 shows some of the relatively good results obtained, which estimate the polymer concentration with sufficient accuracy when using UV-visible light of wavelengths from about 190 nm to about 240 nm. I found that it can be done.

According to such knowledge, in the measurement of the polymer concentration, when the concentration range related to control is wide, UV-visible light with a wavelength of 220 nm is used, and when the concentration range is narrow, it is appropriately selected in the range of 190 nm to 220 nm. It is also possible to use UV-visible light.

According to at least one embodiment described above, based on the concentration of the polymer flocculant remaining in the separated water, which is the water to be treated from which solids have been separated by the solid-liquid separation device, the polymer solution for the water to be treated By having a control unit that controls the injection amount of the dissolution tank that mixes the polymer flocculant and the dissolution water to prepare a polymer solution, and the polymer solution prepared in the dissolution tank is injected into the water to be treated. A solid-liquid separation system comprising: a flocculation tank for flocculating solids in the water to be treated; A decrease in solid-liquid separation performance can be suppressed.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 100,100a,100b,100c,100d... Solid-liquid separation system 1... Dissolution tank 11... 1st stirrer 2... Polymer solution injection pump 3... Aggregation tank 31... 2nd stirrer 4... Solid-liquid Separation device 41 First water tank 42, 42a Water quality meter 43 Third water tank 44 Fourth water tank 5, 5a, 5b Control device 51 Communication unit 52, 52a Memory Part, 53... Measurement data acquisition part, 54, 54a... First injection rate control part, 55... Second injection rate control part, 6... Filtration device, 61... Second water tank, 7... Dilution water injection pump, 90... Solid-liquid separation system 91 Dissolution tank 92 First stirrer 93 Polymer solution injection pump 94 Aggregation tank 95 Second stirrer 96 Solid-liquid separation device

Claims (6)

A dissolution tank for preparing a polymer solution by mixing a polymer flocculant and dissolved water, and a flocculation for flocculating solids in the water to be treated by injecting the polymer solution prepared in the dissolution tank into the water to be treated. A control device for a solid-liquid separation system comprising a tank and a solid-liquid separation device for separating the water to be treated in which the solids are aggregated into solids and water,
Based on the concentration of the polymer flocculant remaining in the separated water, which is the water to be treated in which the solid matter is separated by the solid-liquid separation device and diluted with the dilution water, the injection amount of the polymer solution to the water to be treated. and a control unit that controls the amount of the dilution water injected into the separation water ,
Control device. The control unit controls the injection amount of the polymer solution into the water to be treated based on the correlation between the absorbance of the polymer solution by ultraviolet-visible light having a wavelength of 190 nm to 240 nm and the concentration of the polymer flocculant. do,
A control device according to claim 1 . The control unit, based on the COD (Chemical Oxygen Demand) concentration or SS (Suspended Solid) concentration of the separated water, generates information regarding the accuracy of estimating the concentration of the polymer flocculant remaining in the separated water.
3. A control device according to claim 1 or 2. A dissolution tank for preparing a polymer solution by mixing a polymer flocculant and dissolved water, and a flocculation for flocculating solids in the water to be treated by injecting the polymer solution prepared in the dissolution tank into the water to be treated. A solid-liquid separation method for a solid-liquid separation system, comprising: a tank;
Based on the concentration of the polymer flocculant remaining in the separated water, which is the water to be treated in which the solid matter is separated by the solid-liquid separation device and diluted with the dilution water, the injection amount of the polymer solution to the water to be treated. and controlling the amount of said dilution water injected into said separation water .
Solid-liquid separation method. A dissolution tank for preparing a polymer solution by mixing a polymer flocculant and dissolved water, and a flocculation for flocculating solids in the water to be treated by injecting the polymer solution prepared in the dissolution tank into the water to be treated. A computer functioning as a control device for a solid-liquid separation system comprising a tank and a solid-liquid separation device for separating the water to be treated in which the solids have aggregated into solids and water,
Based on the concentration of the polymer flocculant remaining in the separated water, which is the water to be treated in which the solid matter is separated by the solid-liquid separation device and diluted with the dilution water, the injection amount of the polymer solution to the water to be treated. and controlling the amount of said dilution water injected into said separation water . a controller;
a dissolution tank for preparing a polymer solution by mixing a polymer flocculant and dissolved water;
a flocculating tank for injecting the polymer solution prepared in the dissolving tank into the water to be treated to flocculate solids in the water;
a solid-liquid separation device for separating the water to be treated in which the solids have aggregated into solids and separated water;
a dilution water injection unit for injecting dilution water into the separated water separated by the solid-liquid separation device;
a water quality meter that measures the concentration of the residual polymer flocculant in the separated water into which the dilution water has been injected;
The control device is
Based on the concentration of the residual polymer flocculant measured by the water quality meter, the amount of the polymer solution injected into the water to be treated and the amount of the dilution water injected into the separated water are controlled.
Solid-liquid separation system.

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