JP2002035502A - Flocculation reaction tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flocculation reaction tank capable of supplying sludge to a hermetically closed sludge forcing type dehydrator without separately requiring a pump and not generating clogging. SOLUTION: The flocculation reaction tank is equipped with a reaction tank 1 forming a hermetically closed space, the impeller 4 arranged in the flocculation region 2 of the reaction tank 1, the drive device 4a arranged outside the reaction tank 1, the filter unit 5 arranged in the concentration region 3 of the reaction tank 1, the sludge charging system 6 communicating with the flocculation region 2, the sludge discharge system 7 communicating with the concentration region 3 and the separated liquid discharge system 9 communicating with a filtrate region 8. The filter unit 5 is constituted by alternately laminating fixed plates 10 and rotary plates 11 and interposing spacers 12 between the mutually opposed surfaces of the plates to form a screen 13 and the filtrate region 8 is formed between the screen 13 and the wall surface of the reaction tank 1 by the seal materials 14 provided to the upper and lower ends of the screen 13 and the fixed shaft 15 piercing the fixed plates 10 and the spacers 12 is fixed and held by the seal materials 14 and the movable shaft 16 piercing the rotary shafts 16 is connected to the drive device 4a of the impeller 4 or a separately arranged drive device in a cooperative state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flocculation reaction tank, and relates to a technique for adding and mixing a polymer flocculant or the like for dewatering sludge generated in sewage / wastewater treatment or the like and flocculating the sludge.

[0002]

2. Description of the Related Art Conventionally, excess sludge generated in sewage / wastewater treatment has been dewatered and dried to reduce its volume.
It is very difficult to dewater sludge as it is, and it is essential to add a flocculant to form coarse flocs.

[0003] In recent years, sludge dewatering properties have deteriorated due to poor concentration due to an increase in organic components contained in the sludge. For this reason, attempts have been made to increase the filtration rate and decrease the water content of the cake by concentrating the sludge before putting it into the dehydrator. Examples of the concentrating means include a drum screen type and a stirring tank type.

[0004]

However, the conventional concentrating means such as a drum screen type and a stirring tank type are intended for an open type dehydrator such as a belt press and used under atmospheric pressure. . On the other hand, in recent years, a closed type / sludge press-in type dehydrator such as a screw press has been used due to problems such as odor control. For this reason, when the concentrated sludge concentrated by the conventional drum screen type or stirring tank type concentration means is dewatered by a closed type / sludge press-in type dehydrator, a pump for pressing the concentrated sludge into the dehydrator is separately provided. It is necessary to increase the number, which is a factor of cost increase. In addition, there is a problem that flocculated flocs are destroyed while the concentrated sludge passes through the pump. Furthermore, in conventional concentrating means, wedge wire type screens with relatively little clogging are used as screens, but reversible clogging is inevitable, and regular and continuous screens are required for safe operation. A washing step was required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and achieves space saving by integrally performing aggregation and concentration.
By operating in a closed space under high pressure, it can be supplied to a closed type, sludge press-in type dehydrator without the need for a separate pump, and a flocculation reaction tank that does not clog even in continuous operation The purpose is to provide.

[0006]

In order to solve the above-mentioned problems, a coagulation reaction tank according to the present invention according to claim 1 has a reaction tank forming a closed space therein and one of the reaction tanks in the axial direction. An impeller disposed in a coagulation region formed on the side of the reaction vessel, a driving device for the impeller disposed outside the reaction tank, and a cylindrical filtration unit disposed in a concentration region formed on the other axial side in the reaction tank, A sludge input system that communicates with the area and feeds the raw sludge with the flocculant, and a sludge discharge system that communicates with the enrichment area.
A separation liquid discharge system that communicates with the filtrate area of the filtration unit, the filtration unit alternately stacks a plurality of ring-shaped fixed plates and rotating plates, and a predetermined distance between both opposed plate surfaces. A screen is formed with a spacer forming a slit interposed, and the filtrate region is formed between the outer periphery of the screen and the wall surface of the reaction tank with a ring-shaped sealing material arranged at the upper and lower ends of the screen, and each fixed. A fixed shaft that penetrates the plate and each spacer is fixedly held by the sealing material, and a movable shaft that penetrates each rotary plate is interlocked to a drive device of the impeller or a drive device that is separately disposed. is there.

[0007] With the above-described configuration, raw sludge with a coagulant is injected into the reaction tank at a predetermined pressure from the sludge charging system. In the flocculation region of the reaction tank, the raw sludge and the flocculant are stirred by the impeller rotated by the driving device to generate a flocculation reaction and form floc. The floc formed in the flocculation region moves to the concentration region and flows into the filtration unit.

In this state, there is a predetermined pressure difference between the inside and outside of the filtration unit due to the pressure of the sludge feeding system, and the pressure difference is higher than the slit formed by the spacer between the rotating plate and the fixed plate of the screen. Small flocculated flocs and separated liquid are discharged from the concentration area inside the filtration unit to the filtrate area outside through the slit, while flocculants larger than the slit are gradually concentrated in the filtration unit.

The slit width of this screen can be adjusted to a slit width suitable for various types of sludge by selecting the thickness of the spacer and the thickness of the fixed plate and the rotating plate.
1 is larger than the thickness t2 of the rotating plate and the fixed plate having the same thickness, and is determined in a range satisfying the following relationship.

0 <(t1−t2) / 2 <1 mm The concentrated sludge in the concentration area is injected into the dehydrator in the next step through the sludge discharge system from the concentration area and contains small flocculants discharged to the filtrate area. The separated liquid is discharged to the outside of the reaction tank through the separated liquid discharging system.

Therefore, the concentrated sludge containing flocculated floc can be injected into the dehydrator in the next step by utilizing the pressure of the sludge input system without re-injecting the concentrated sludge using a pump or the like.
Concentrated sludge can be supplied to a sludge press-in type dehydrator, which was difficult to apply in a conventional open-to-air type concentrator, without destroying flocculated flocs.

In addition, a reversible obstruction made up of fine floc and floc and a flocculant adhesive layer adheres to the inner peripheral portion of the filtration unit, and the upper and lower surfaces of the rotating plate and the fixed plate, which causes an increase in filter medium resistance. However, as the rotating plate rotates continuously and relatively to the fixed plate, the obstruction is ground and discharged together with the separated liquid. Due to this self-cleaning effect, clogging of the screen is eliminated, and stable concentration can be performed without requiring a periodic cleaning step.

According to a second aspect of the present invention, there is provided an agglutination reaction tank according to the present invention, wherein a flow meter interposed in a sludge input system, a fixed amount pump interposed in a separated liquid discharge system capable of variably adjusting a set flow rate, and an output of the flow meter A calculator that receives a signal and instructs the set flow rate to the metering pump, and the calculator is a ratio of the flow rate of the separated liquid taken out of the reaction tank through the separated liquid discharge system to the flow rate of the raw sludge supplied from the sludge input system to the reaction tank. Is set to the set ratio.

With the above configuration, the separation capacity of the filtration unit depends on the slit width of the screen and the filtration pressure for extruding the separated liquid containing the flocculated floc smaller than the slit width, and the filtration pressure is a pressure difference between the inside and the outside of the screen.
Since the sludge flow rate and pressure in the sludge input system are constant, the differential pressure decreases as the separation liquid discharge speed increases and the back pressure in the filtrate region increases, and the separation liquid discharge speed increases and the back pressure in the filtrate region decreases. The smaller the pressure, the greater the differential pressure.

Therefore, as the ratio of the separation liquid flow rate to the raw sludge flow rate increases, the differential pressure increases and the separation capacity increases, and as the ratio of the separation liquid flow rate to the raw sludge flow rate decreases, the differential pressure decreases. Separation ability decreases.

For this reason, the set ratio in the arithmetic unit is adjusted in accordance with the concentration property of the coagulated sludge, the set flow rate in the metering pump is adjusted, the rotation speed of the pump is controlled, and the separation taken out of the reaction tank through the separated liquid discharge system. Increase or decrease the liquid flow. The ratio between the raw sludge flow rate f1 and the separated liquid flow rate f2 is determined in a range satisfying the following relationship.

0.1 ≦ (f2 / f1) ≦ 0.9 By this operation, as the concentration of the coagulated sludge is lower, the ratio of the flow rate of the separated liquid to the flow rate of the raw sludge is increased to increase the separation capacity, and As the concentration is higher, the ratio of the flow rate of the separated liquid to the flow rate of the raw sludge is made smaller to suppress the separation capacity, so that the solid matter recovery rate can be maintained better.

According to a third aspect of the present invention, there is provided a coagulation reaction tank according to the present invention, wherein a differential pressure gauge interposed between the reaction tank and the separated liquid discharge system, and a pressure capable of variably adjusting a set pressure interposed in the separated liquid discharge system. A pressure control valve that receives the output signal of the differential pressure gauge and indicates a set pressure to the pressure control valve. The calculator calculates a differential pressure between the internal pressure of the reaction tank and the internal pressure of the separated liquid discharge system. The pressure is controlled.

With the above configuration, the separation capacity of the filtration unit depends on the slit width of the screen and the filtration pressure for extruding the separated liquid containing the flocculated floc smaller than the slit width, and the filtration pressure is a differential pressure between the inside and the outside of the screen.
As the differential pressure increases, the separation capability increases, and as the differential pressure decreases, the separation capability decreases.

Since the sludge flow rate and the pressure in the sludge feeding system are constant, the differential pressure decreases as the back pressure in the filtrate region increases, and the differential pressure increases as the back pressure in the filtrate region decreases.

For this reason, the differential pressure set in the arithmetic unit is adjusted in accordance with the concentration of the coagulated sludge, the pressure set in the pressure control valve is adjusted, and the internal pressure of the separated liquid discharge system is controlled by controlling the opening of the pressure control valve. Increase or decrease. Internal pressure P1 of this reaction tank
And the internal pressure P2 of the separated liquid discharge system are determined in a range satisfying the following relationship.

1 kPa ≦ (P1−P2) ≦ 50 kPa By this operation, as the concentration of the coagulated sludge becomes lower, the differential pressure between the internal pressure of the reaction tank and the internal pressure of the separated liquid discharge system is increased to increase the separation capacity. As the concentration of the coagulated sludge is higher, the differential pressure between the internal pressure of the reaction tank and the internal pressure of the separated liquid discharge system is reduced to suppress the separation ability, so that the solids recovery rate can be favorably maintained.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an agglutination reaction tank according to an embodiment of the present invention will be described with reference to the drawings. 1 and 2, a reaction vessel 1 has a closed space formed therein. In the closed space, an agglomeration region 2 is formed on the upper side of the reaction vessel 1 in the axial direction. Is formed on the lower side of the lower portion to form a lower discharge type.

An impeller (stirring blade) 4 is arranged in the coagulation region 2 of the reaction tank 1, and a driving device 4 a of the impeller 4 is arranged outside the reaction tank 1. A filtration unit 5 in the shape of a circle is arranged. Connected to the flocculation region 2 is a sludge input system 6 for pumping raw sludge with a flocculant,
A sludge discharge system 7 is connected to the concentration area 3, and a filtration unit 5 is connected.
A separation liquid discharge system 9 is connected to a filtrate region 8 described later.

As shown in FIG. 2, in the filtration unit 5, a plurality of ring-shaped fixed plates 10 and rotating plates 11 are alternately stacked, and a predetermined slit is formed between both opposed plate surfaces. Screen 13 with spacer 12 interposed
The screen 13 has upper and lower ends of coagulated sludge,
A ring-shaped sealing material 14 for separating the separated liquid and the concentrated sludge from each other is arranged to form a filtrate region 8 around the outer periphery of the screen 13 and the wall surface of the reaction tank 1.

Ears 10 formed on the outer periphery of each fixing plate 10
a and a fixed shaft 15 penetrating through each spacer 12 is fixedly held by a sealing material 14, and a lug 11 a of each rotating plate 11 is provided.
The movable shaft 16 penetrating through the impeller 4
, The impeller 4 and the rotating plate 11 rotate integrally. When the movable shaft 16 is connected to a driving device separately disposed outside the tank, the rotating speed of the impeller 4 (stirring speed) and the rotating speed of the rotating plate 11 can be controlled separately. Instead of rotating in only one direction, the rotating direction can be reversed at regular intervals.

As shown in FIG. 3, the reaction tank 1 can be formed as an upper discharge type by forming an agglomeration area 2 on the lower side and an enrichment area 3 on the upper side. The lower discharge type and the upper discharge type are selected according to the sedimentation of flocculated floc.

As shown in FIG. 4, the sludge input system 6 has a sludge pump 18 for pumping the raw sludge and a sludge flow meter 19 for measuring the flow rate of the raw sludge. The supply system 20 has a chemical solution pump 21 and a chemical solution flow meter 22 for measuring the flow rate of the flocculant. The separated liquid discharge system 9 has a fixed amount pump 23 capable of variably adjusting a set flow rate.
The metering pump 23 is connected to a calculator 24 which receives an output signal of the sludge flow meter 19 and instructs the metering pump 23 to set a flow rate. The arithmetic unit 24 controls the ratio of the flow rate of the separated liquid taken out of the reaction tank 1 through the separated liquid discharge system 9 to the flow rate of the raw sludge supplied from the sludge input system 6 to the reaction tank 1 at a set ratio. The sludge discharge system 7 is connected to a press-fit type dehydrator 25.

The operation of the above configuration will be described below. The raw sludge is pumped through the sludge feeding system 6 by the sludge pump 18, a coagulant supplied from the coagulant supply system 20 by the chemical liquid pump 21 is added in the middle thereof, and the sludge is pressed into the reaction tank 1 with the coagulant at a predetermined pressure. . Coagulation area 2 of reaction tank 1
In the above, the raw sludge and the flocculant are stirred by the impeller 4 rotated by the driving device 4a to cause a flocculation reaction, thereby forming flocculated flocs. The coagulated sludge with coagulated flocs formed in the coagulation region moves sequentially to the concentration region 3 and flows into the filtration unit 5.

In the concentration region 3, the rotating plate 11 that rotates integrally with the impeller 4 rotates relatively and continuously with respect to the fixed plate 10. In the filtration unit 5, a predetermined pressure difference due to the pressure of the sludge input system 6 exists between the concentration area 3 and the filtrate area 8 bordering the screen 13. 13 rotating plates 11
Separation liquid containing coagulated floc smaller than the slit formed by the spacer 12 between the plate and the fixing plate 10 is discharged from the concentration area 3 inside the filtration unit 5 to the filtrate area 8 outside through the slit. Thus, the coagulated sludge inside the filtration unit 5 is gradually concentrated into concentrated sludge.

The slit width of the screen 13 can be adjusted to a slit width suitable for various sludge properties by selecting the thickness of the spacer 12 and the thickness of the fixed plate 10 and the rotating plate 11. The thickness t1 of the spacer is determined within a range that is larger than the thickness t2 of the rotating plate 11 and the fixed plate 10 having the same thickness and that satisfies the following relationship.

0 <(t1−t2) / 2 <1 mm The concentrated sludge in the concentration area 3 passes through the sludge discharge system 7 and is injected into the press-in type dehydrator 25 in the next step. Therefore, the concentrated sludge containing the flocculated floc is supplied to the next step using the discharge pressure of the sludge pump 18 of the sludge introduction system 7 without being re-pressed by a separate pump or the like. It can be supplied to the press-fit type dehydrator 25, which has been difficult to apply, without breaking the flocculated flocs.

The separated liquid containing the small flocculated flocs discharged into the filtrate area 8 passes through the separated liquid discharge system 9 and is supplied to the metering pump 23.
Is discharged to the outside of the reaction tank 1. A reversible obstruction composed of a fine flocculent floc and a flocculant adhesive layer adheres to the inner peripheral portion of the filtration unit 5 and the upper and lower surfaces of the rotary plate 11 and the fixed plate 10, which causes an increase in filter medium resistance. As the rotary plate 11 rotates relative to the fixed plate 10 continuously, the obstruction is ground and discharged to the filtrate area 8 together with the separated liquid. Due to this self-cleaning effect, clogging of the screen 13 is eliminated, and stable concentration can be performed without requiring a periodic cleaning step.

The separation capacity of the filtration unit 5 depends on the slit width of the screen 13 and the filtration pressure for extruding a separated liquid containing flocculated flocs smaller than the slit width.
The filtration pressure is a differential pressure between the inside and the outside of the screen 13. Since the sludge flow rate and the pressure in the sludge input system 6 are constant, the differential pressure increases as the separation liquid discharge is slow and the back pressure in the filtrate region 8 is large. The differential pressure increases as the separation liquid is discharged immediately and the back pressure in the filtrate region 8 is smaller.

Therefore, as the ratio of the separation liquid flow rate to the raw sludge flow rate increases, the differential pressure increases and the separation capacity increases, and as the ratio of the separation liquid flow rate to the raw sludge flow rate decreases, the differential pressure decreases. Separation ability decreases.

For this reason, the set ratio in the calculator 24 is adjusted in accordance with the concentration of the coagulated sludge, the set flow rate in the metering pump 23 is adjusted, and the rotation speed of the metering pump 23 is controlled to pass through the separated liquid discharge system 9. The flow rate of the separated liquid taken out of the reaction tank 1 is increased or decreased. The raw sludge flow rate f1 and the separated liquid flow rate f
The ratio to 2 is determined in a range satisfying the following relationship.

0.1 ≦ (f2 / f1) ≦ 0.9 By this operation, as the concentration of the coagulated sludge is lower, the ratio of the flow rate of the separated liquid to the flow of the raw sludge is increased to increase the separation capacity, and As the concentration is higher, the ratio of the flow rate of the separated liquid to the flow rate of the raw sludge is made smaller to suppress the separation capacity, so that the solid matter recovery rate can be maintained better.

As an operation control method, it is also possible to configure as shown in FIG. In FIG. 5, the differential pressure gauge 26
Is interposed between the reaction tank 1 and the separated liquid discharge system 9, and the separated liquid discharge system 9 is provided with a pressure regulating valve 27 capable of variably adjusting a set pressure, and the pressure regulating valve 27 is provided with a differential pressure gauge A computing unit 2 which receives an output signal of 26 and instructs a pressure adjustment valve 27 to set pressure.
8 are connected. The arithmetic unit 28 controls a differential pressure between the internal pressure of the reaction tank 1 and the internal pressure of the separated liquid discharge system 9 to a set differential pressure.

In this configuration, the separation capacity of the filtration unit 5 depends on the slit width of the screen 13 and the filtration pressure for extruding the separated liquid containing the flocculated floc smaller than the slit width. Yes, the separation capacity increases as the differential pressure increases, and the separation capacity decreases as the differential pressure decreases. Since the sludge flow rate and pressure in the sludge input system 6 are constant, the differential pressure decreases as the back pressure in the filtrate region 8 increases, and the differential pressure increases as the back pressure in the filtrate region 8 decreases.

For this reason, the set differential pressure in the calculator 28 is adjusted in accordance with the concentration of the coagulated sludge, the set pressure in the pressure adjusting valve 27 is adjusted, and the separation liquid discharge system 9 is controlled by controlling the opening of the pressure adjusting valve 27. Increase or decrease the internal pressure of. The differential pressure between the internal pressure P1 of the reaction tank 1 and the internal pressure P2 of the separated liquid discharge system 9 is determined in a range satisfying the following relationship.

1 kPa ≦ (P1−P2) ≦ 50 kPa By this operation, the lower the concentration of coagulated sludge, the lower the reaction tank 1
The separation pressure is increased by increasing the pressure difference between the internal pressure of the reactor and the internal pressure of the separation liquid discharge system 9, and the higher the concentration of the coagulated sludge, the higher the internal pressure of the reaction tank 1 and the internal pressure of the separation liquid discharge system 9. By suppressing the separation ability by reducing the differential pressure of the solid solution, the recovery rate of solids can be favorably maintained.

[0042]

As described above, according to the present invention, concentrated sludge containing flocculated floc can be re-pressed with a pump or the like without re-injection.
It can be injected into the dehydrator in the next process using the pressure of the sludge input system, so it can be applied to the sludge press-in type dehydrator, which was difficult to apply with the conventional open-air concentrator, without breaking the floc. It can supply concentrated sludge. Also,
The reversible obstruction, which causes an increase in the resistance of the filter medium, can be crushed and discharged by rotating the rotating plate relatively and continuously with respect to the fixed plate. Clogging is eliminated, and stable concentration can be performed without requiring a periodic washing step.

The set ratio in the arithmetic unit is adjusted in accordance with the concentration of the coagulated sludge, and the lower the concentration of the coagulated sludge, the greater the ratio of the flow rate of the separated liquid to the flow of the raw sludge to increase the separation capacity. As the concentration of the sludge is higher, the ratio of the flow rate of the separation liquid to the flow rate of the raw sludge is reduced to suppress the separation ability, so that the solid matter recovery rate can be maintained better.

The differential pressure set in the arithmetic unit is adjusted according to the concentration of the coagulated sludge, and the lower the concentration of the coagulated sludge, the lower the pressure difference between the internal pressure of the reaction tank and the internal pressure of the separated liquid discharge system. Recovering solids by increasing the separation capacity by increasing the concentration and reducing the differential pressure between the internal pressure of the reaction tank and the internal pressure of the separation liquid discharge system as the concentration of the coagulated sludge is higher The rate can be maintained well.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an agglutination reaction tank according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a filtration unit in the embodiment.

FIG. 3 is a longitudinal sectional view showing an agglutination reaction tank according to another embodiment of the present invention.

FIG. 4 is a schematic view showing an operation control method of the agglutination reaction tank of the present invention.

FIG. 5 is a schematic diagram showing another operation control method of the agglutination reaction tank of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction tank 4 Impeller (stirring blade) 4a Drive device 5 Filtration unit 6 Sludge introduction system 7 Sludge discharge system 8 Filtrate area 9 Separated liquid discharge system 10 Fixed plate 11 Rotating plate 12 Spacer 13 Screen 14 Sealing material 15 Fixed shaft 16 Movable Shaft 19 Sludge flow meter 23 Metering pump 24 Computing unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) B01D 29/09 B01D 29/46 A 29/62 C 29/46 Z C02F 11/12 D B01D 29/02 G C02F 11/12 29/38 580Z (72) Inventor Shinji Oba 1-47, Shishitsuhigashi 1-chome, Naniwa-ku, Osaka-shi, Osaka F-term (reference) 4D059 AA06 BE15 BE31 BE56 CB09 DB11 EA02 EA11 EB02 EB11

Claims (3)

[Claims] 1. A reaction tank forming an enclosed space therein, an impeller disposed in an agglomeration region formed on one side of the reaction tank in an axial direction, a driving device of the impeller disposed outside the reaction tank, A cylindrical filtration unit disposed in the concentration area formed on the other side in the axial direction in the tank, a sludge input system communicating with the coagulation area, a sludge discharge system communicating with the concentration area, and a filtrate area of the filtration unit. The filtration unit includes a plurality of ring-shaped fixed plates and a rotating plate that are alternately stacked, and a spacer that forms a predetermined slit between both opposed plate surfaces. A screen is formed with intervening, and the filtrate area is formed between the outer periphery of the screen and the wall surface of the reaction tank with a ring-shaped sealing material disposed at the upper and lower ends of the screen, and penetrates each fixing plate and each spacer. Fixed to place Flocculation reaction tank was held at the said sealing material, characterized in that the movable axis disposed through the respective rotating plates linked connected to a driving unit for driving device or separately arranged in the impeller of. 2. A flow meter interposed in a sludge introduction system, a fixed amount pump interposed in a separated liquid discharge system capable of variably adjusting a set flow amount, and instructing a set flow amount to the fixed amount pump upon receiving an output signal of the flow meter. A computing unit for controlling the ratio of the flow rate of the separated liquid taken out from the reaction tank through the separated liquid discharge system to the set amount of the raw sludge flow supplied to the reaction tank from the sludge input system. The agglutination reaction tank according to claim 1. 3. A differential pressure gauge interposed between the reaction tank and the separated liquid discharge system, a pressure adjusting valve variably adjustable for a set pressure interposed in the separated liquid discharge system, and an output signal of the differential pressure gauge. An arithmetic unit for instructing a set pressure to the pressure regulating valve, wherein the arithmetic unit controls a differential pressure between an internal pressure of the reaction tank and an internal pressure of the separated liquid discharge system to a set differential pressure. 2. The agglutination reaction tank according to 1.