JP2001259308A - Flocculation and concentration apparatus and flocculation and concentration method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of water quality caused by adhesion of huge flocs of flocculated microorganism and flowing-in soil to bottom of a floc formation tank 6 and their putrefaction in the case the bottom is formed in the tank 6. SOLUTION: A floc formation tank has a shape formed by joining a cylinder and a right cone having a head and the shape satisfies the following: A2/B2=50-280 wherein A denotes the diameter of the cylinder and B denotes the diameter of the head of the (right) cone having the head. Even if water discharge amount is greatly fluctuated owing to a holiday or the like, the supernatant liquid 25 in a precipitation tank 29 is supplied to the (right) cone having the head from a fluidizing and circulating pump 19 through a blowing-up pipe 18 with the diameter (B) connected to the head 17 of the cone having the head. If the supply is performed at lowest a supply speed which is the minimum fluidizing speed in a circle surface area equivalent to B2×20 as the surface area of the circle formed by cutting the (right) cone having the head in a round slice, the flocs are moved fiercely in the section lower than the position of the cutting in a round slice and the flocs thus do not adhere to improve the water quality and operation control is made easy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prevents activated sludge from stagnating and decaying in the bottom of a flock forming tank on a holiday when no water is discharged from a factory, flows into a drainage ditch of soil in the factory, and buries a drainage pipe. Groundwater may flow into the wastewater treatment facility together with the soil from the cracks, and the soil and the activated sludge may form a huge floc with a high specific gravity, making fluidization in the forming tank impossible. Microorganisms. It relates to preventing the soil from sticking and agglomerated rot.

[0002]

2. Description of the Related Art In a conventional facility for biological treatment of wastewater, there is no apparatus for enlarging fine particles to a sedimentation speed of 1000 times or more than naturally flocculated floc. The inflow of the specific gravity of soil 2.5 and the specific gravity of activated sludge 1.04) was a desirable phenomenon for improving the settling performance of activated sludge.

[0003]

Conventionally, the preferred soil for improving sedimentation performance in a sewage treatment plant is 2.5 in water.
-1 = 1.5, activated sludge 1.04-1 = 0.04
1.5 / 0.04 = 37.5 times heavier soil. In this system, in which soil and activated sludge are fluidized together in a floc forming tank to form a giant floc, and the floating giant floc is discharged from the tank, maintaining fluidity on holidays was a major issue. .

According to the present invention, fine particles are not discharged as fine particles from the discharge port of the filler tube in the floc forming tank, but the flocs formed from the fine particles can be operated in the floc forming tank at a flow rate that does not cause collisional separation. A system for eliminating the presence of fine particles in the tank, forming a fluidized bed even on holidays, eliminating sedimentation of settled sludge on the tank bottom, and continuing economical operation, the shape of the floc forming tank and other operating methods It is intended to provide.

[0005]

In order to achieve the above object, the bottom of the floc forming tank is formed in a funnel shape [truncated (straight) cone] in order to maintain fluidization at a small flow rate. ]
And a pipe corresponding to the funnel descending pipe is a blow-up pipe 18 connected to a fluid circulation pump 19, and the sedimentation tank supernatant liquid is blown from the blow-up pipe into the floc formation tank at a speed at which a fluidized bed is formed. Supplied from a fluid circulation pump.

[0006] The fluidization rate of the floc forming the above-mentioned fluidized bed is a rate at which the soil adheres to the activated sludge, and the specific gravity varies, but the flow rate of the truncated (straight) cone head is 2 to 10 cm / s.
On the other hand, the flow rate in the cylindrical portion of the floc forming tank is 0.005
０．２0.2 cm / s, the difference in specific gravity between floc and supernatant water is small, and the phenomenon of separation of fine particles from flocs due to collision between flocs is not observed. Even if separation occurs, it is determined that the separated fine particles are aggregated during repeated ascending of the floc forming tank.

Since the floc forming tank is installed in the sedimentation tank below the level of the sedimentation tank, the discharge water of the floc forming tank is arranged to be discharged from the weir of the sedimentation tank.
The supernatant water of the settling tank can be supplied to the floc forming tank through a blow-up pipe by a fluid circulation pump to form a fluidized bed.
Even on holidays when no water is discharged, the fluid circulation pump can be operated to continue fluidization in the floc forming tank, and during that time, it is not necessary to supply water to the pump.

[0008] The flow velocity in the blow-up pipe is set to 1 /
When the fluid circulation pump is operated for 1 to 20 minutes at a rate of 2 to 1/10, particles having a specific gravity higher than the target specific gravity fall down the blow-up pipe and are stored in the storage tank 21 immediately below the blow-up pipe. Then, the liquid is discharged from the discharge valve (22) at the bottom of the storage tank to the sedimentation tank, or is suctioned out of the system.

[0009]

[Function] The fluidization speed in the floc forming tank is 0.005 to 0.005.
The specific gravity difference between the supernatant water and the floc is as small as 0.02 to 0.04, there is no separation phenomenon due to the collision between the flocs, and the flow rate in the truncated (straight) cone is the activated sludge tank. 1/10 to 1/3 of the flow velocity in the inside, there is no peeling phenomenon of fine particles from the floc, there is no bottom fixed in the floc forming tank due to settling sludge at the bottom of the tank, and the amount increased to the floc forming tank on holidays When the supply pump of the liquid (activated sludge treatment liquid) stops, the blow-up pipe connected to the head of the truncated (straight) cone
It is started to transfer the supernatant water at a speed of 〜１０10 cm / s through a fluid circulation pump.

[0010]

Embodiment 1 An embodiment will be described with reference to the drawings. In FIG. 1, the coagulation and concentration apparatus comprises a liquid supply chamber 3 installed in a sedimentation tank 29 and a floc forming tank 2 arranged at a lower position. The liquid supply chamber is a distribution chamber 5 for distributing the liquid 1 to be treated.
And a dispersion chamber 4. A spiral mixing pipe 9 for flowing down the liquid from the dispersion chamber 4 and an increasing pipe 7 for flowing down the liquid to be treated from the distribution chamber 5 are joined at a downstream junction 8. The spiral mixing tube 9 is provided with a spiral injection tube 10 having an opening in the downstream direction inside. In the spiral mixing tube 9, a mixed solution obtained by mixing tap water 26 and the liquid 1 to be treated in the mixer 28 and two liquids having different potentials individually supplied to the spiral injection tube 10 are brought into contact with each other through the opening to form a floc. Then, a floc-containing liquid is obtained. Therefore, the double tube of the spiral mixing tube and the spiral injection tube 10 becomes a coagulation tube. The contact is preferably performed in a laminar flow state. The floc-containing liquid is further mixed with the processing liquid flowing down in the extender pipe 7 at the junction 8 downstream of the expander pipe, and the flocs in the floc-containing liquid become nuclei to aggregate fine particles in the liquid to be treated. Let it be a mass flock.

In a treatment facility in which fine solids having a large specific gravity (30 microns or less) other than soil and other microorganisms flow into a floc-forming tank having a tank bottom, the fine solids and microorganisms are deposited on the floc-forming tank bottom. Forms a floc with a high specific gravity in the floc formation tank, and when the amount of liquid from the discharge port of the expansion pipe is insufficient at the bottom of the floc formation tank for circulation in the tank,
In order to prevent flocks from settling and sticking to the bottom of the tank to form lumps when the discharged water is zero, a truncated (straight) conical head should be placed at the bottom of the cylindrical part of the flock forming tank. 17 is connected downward, a blow-up pipe 18 having a side pipe is connected to the truncated (straight) conical head 17, and a flow circulation pump 19 is connected to the side pipe.
And the fluid circulation pump is started to supply the supernatant 25 at a minimum fluidization speed or higher into the floc forming tank.

The diameter of the truncated (straight) cone connected to the diameter (A) of the cylinder forming the fluidized bed (B) is A ² / B ² =
At a flow rate of 50 to 280 times the cylindrical portion, preferable operation can be maintained without separation from the floc.

[0013]

Since the present invention is configured as described above, it has the following effects.

At the bottom of the floc forming tank, a truncated (straight) cone and a blow-up pipe connected to the head are provided, and the supernatant of the sedimentation tank is supplied from the fluid circulation pump to the blow-up pipe with a small amount of liquid per unit time. Only in the truncated (straight) cone, the fluidization speed of the straight cylinder is reduced from intense fluidization to 0.005 to 0.2 cm.
/ S, and the change in speed reaches 1/40, and stable operation can be secured.

The value of the square of the blow-up pipe diameter (B) is 10 to 10.
Diameter of a circle made by cutting a 20-fold truncated (straight) cone (C)
By operating the fluid circulation pump at a speed where the value of the square slightly exceeds the minimum fluidization speed, it is possible to prevent the activated sludge from sticking to the bottom of the floc formation tank on weekdays and holidays.

The liquid to be supplied to the floc-forming tank is obtained by fluidizing the floc of activated sludge in the floc-forming tank from the surface of the floc-forming tank through the upflow pipe from the settling tank supernatant through a flow circulating pump to raise the sludge. There is almost no need to replenish the supernatant since it is not discharged out of the system just by circulating to the supernatant.

The flow rate of the blow-up tube is increased 1 to 3 times a week,
The flow rate was reduced to 0.05 to 3 cm / s for 0 minute, dropped into the storage tank immediately below the blow-up pipe, and the dropped floc was discharged from the discharge valve of the storage tank into the sludge in the sedimentation tank or out of the system to minimize the floc formation tank. Fluidization speed fluctuations can be reduced.

The diameter of the truncated (straight) cone connected to the diameter (A) of the cylinder forming the fluidized bed (B) is A ² / B ²
= 50 to 280 times, and the diameter of the truncated (straight) cone head = the minimum diameter of the blow-up tube is 40 mm, the flow velocity in the cylindrical portion of the floc forming tank becomes gentle, and the collision between the floc and the floc surface occurs. No peeling phenomenon is observed at all.

The floc having a large specific gravity can be continuously operated with a minimum diameter of the blow-up pipe of 40 mm in order to drop the supernatant liquid from the fluid circulation pump at a reduced feed rate for 20 minutes and drop it into the storage tank.

[Brief description of the drawings]

FIG. 1 is a flow circulation operation diagram to a floc forming tank in a sedimentation tank.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 To-be-processed liquid 2 Coagulation | concentration concentration chamber 3 Supply liquid chamber 4 Dispersion chamber 5 Distribution chamber 6 Floc forming tank 7 Expansion pipe 8 Expansion pipe branch pipe 9 Spiral mixing pipe 10 Spiral injection pipe 11 Injection liquid 12 Injection liquid outlet 13 Straight cut Conical Top Diameter 14 Collision Mixing Tube 15 Cylinder 16 Truncated Straight Cone 17 Truncated Straight Cone Head 18 Blow Up Tube 19 Flow Circulation Pump 20 Feed Liquid Receiving One Port 21 Reservoir 22 Valve at Tank Bottom of Reservoir 23 Downcomer 24 Increaser Outlet 25 Supernatant 26 Tap water (groundwater) 27 Downcomer outlet 28 Mixer 29 Sedimentation tank

Claims (4)

[Claims] 1. A liquid to be treated in which various kinds of fine particles of 50 microns or less (soil particle diameter of 50 microns or less) having a specific gravity difference of 1.5 times or more are mixed irregularly at different mixing ratios ( A coagulating / concentrating apparatus for forming a biologically treated contaminated liquid (1) into a huge floc on a regular basis, comprising: a) a supply chamber (3) for supplying the liquid to be treated (1) and a coagulating / concentrating chamber (2) B) the liquid supply chamber is composed of a dispersion chamber (4) for dispersing the liquid to be treated and a distribution chamber (5) for distributing the liquid to be treated; c) one end is open to the distribution chamber, and the other end is flocking. An expanding pipe (7) opening to the forming tank (6) is provided, and an expanding pipe branch pipe (8) for receiving the mixed solution is provided in the middle. D) One end is connected to the dispersion chamber (4), and the other end is connected to the expanding pipe ( 7) A spiral mixing tube (9) opened inside is provided, and a spiral injection tube (10) is provided inside with the mixing tube outside. The double pipe has a spiral pipe structure. E) A spiral injection pipe (10) for injecting the injection liquid (11) into the spiral mixing pipe is connected to the injection liquid discharge port (12).
Has a structure opened toward the downstream direction of the liquid to be treated flowing in the mixing tube, and f) a terminal downstream of the spiral mixing tube is a collision mixing tube (1).
G) the side wall of the floc forming tank is cylindrical and the lower side of the cylinder (15) and the lower side of the side wall of the truncated (straight) cone (16) are connected; With the truncated (straight) cone head (17) down and connected almost perpendicularly to the blow-up pipe (18) of the same diameter as the truncated (straight) cone top diameter (13), the flow circulation pump ( 1
H) A storage tank (21) is provided for receiving a floc having a high specific gravity falling at the end of the blow-up pipe, and a valve (22) is provided on the lid at the bottom of the storage tank. When floc having a large specific gravity accumulates in the storage tank, a valve at the bottom of the tank is opened, and an opening is discharged on the sludge interface of the settling tank (29). When the discharge is completed, the valve (22) is returned, and fine particles are returned. An aggregating and concentrating apparatus characterized in that particles having a large difference in specific gravity, which hardly form a fluidized bed in a floc forming tank, are discharged out of the system, and an idealized fluidized bed is always maintained in the floc forming tank. 2. The diameter (equivalent diameter) of the head of a truncated (straight) cone (pyramid) connected to the diameter (equivalent diameter of a rectangular cylinder) (A) of the cylinder forming the fluidized bed (B), The value obtained by dividing the value of the square by the value of the square of B is 50 to 280 times, and the diameter (equivalent diameter) of the blow-up pipe (18) connected to the head of the truncated (straight) cone.
Is the diameter of the truncated (straight) conical head, with a minimum diameter of 40
A coagulating and concentrating apparatus using a reactor having a diameter of 0.2 mm as a floc forming tank. 3. The method according to claim 1, wherein
When the liquid to be treated (1), in which various kinds of fine particles of 50 microns or less having a specific gravity difference of 1.5 times or more and mixed at different mixing ratios, are routinely formed into a giant floc, Injection liquid (liquid to be treated) (11) discharged from spiral injection pipe (10) and spiral mixing pipe (9)
The liquid to be treated is brought into laminar flow contact with a mixed liquid flowing in the liquid [a liquid having a different electrolyte concentration from the liquid to be treated, for example, a tap water (26) and a liquid obtained by treating the liquid to be treated with the mixer (28)]. The fine particles therein form flocs. B) With respect to the amount of the floc-containing liquid discharged from the discharge port of the spiral mixing pipe (9) of the apparatus, a collision mixing pipe (14) Liquid to be processed flowing through 3) -300
C) forming a fluidized bed in the floc forming tank by discharging from the discharge pipe (24) into the floc forming tank (6); Aggressive collision repeatedly aggregated 5
A large floc grows at a residence time of ６０60 minutes, and most of the feed liquid is supplied from the surface of the fluidized bed of the floc forming tank to the supernatant liquid (2
5) The giant flocks formed in the floc forming tank are floated on the upward flow of 0.01 cm / s or more in the tank. Down the downcomer having an inclination angle of 15 to 45 degrees, and the outlet of the downcomer (27) is located below the sludge interface of the settling tank at 50 to 2 degrees.
e) The liquid to be treated in which fine particles having a specific gravity of 50 microns or less are mixed in the biological treatment contaminated liquid also passes through the above steps a) b) c). (25) A fluid circulation pump (1) for supplying tap water or groundwater
9), an upward vortex is sent from the fluid circulation pump to the truncated (straight) cone (16) through the blow-up pipe at the bottom of the floc forming tank, and particles having a large specific gravity are allowed to flow. The flow velocity of the blow-up pipe is lowered, and the liquid is separated by lowering it into the storage tank (21) immediately below it. Blow up tube (18) once or twice a week for 3 to 20 minutes by forming floc of diameter
Flow rate is reduced to 0.05 to 3 cm / s, and a heavy floc is dropped into the storage tank (21) immediately below the blow-up pipe. If the heavy floc accumulates in the storage tank, a discharge valve is provided at the bottom of the storage tank. In (22), it is discharged into the settling tank sludge. G) Fine particles having a specific gravity of 1.5 or more are caused to flow in the truncated (straight) conical portion to eliminate the stagnation zone, and the giant particles having a large specific gravity are stored in a storage tank immediately below the blow-up pipe in a storage tank having a specific gravity of 1.
A flocculation / concentration method, wherein a huge floc of 1 or less small fine particles is separated into a sedimentation tank by descending a downcomer pipe opened at the top of the floc formation tank. 4. The flow circulating pump of the floc forming tank is operated while the wastewater treatment apparatus is in operation or stopped, and a truncation (straight) of 10 to 20 times the value of the square of the blow-up pipe diameter (B).
A coagulating / concentrating apparatus and a coagulating / concentrating method, characterized in that the value of the square of the diameter (C) of a circle formed by cutting a cone is supplied at a speed higher than a speed capable of maintaining a minimum fluidization speed.