JP3235141B2 - Wastewater treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment apparatus for domestic wastewater and industrial wastewater, and more particularly to a wastewater treatment apparatus provided with an aerator capable of supplying fine bubbles such as oxidizing gas and methane gas to wastewater.

[0002]

2. Description of the Related Art
The aeration in the wastewater treatment equipment is based on a method in which air is broken down by pressurizing and ejecting air into the wastewater from the tubular or plate-like aerator holes installed in the aeration tank, and shearing is performed by rotating blades or bubble jets. There are two methods of introducing air into a forced drainage stream and subdividing it.

[0003] In the former system, there are so-called "diffusing tube type", "diffusing plate type", "diffusing cylinder type", and the like.
For example, pressurized air is blown out into drainage from pores formed in a pipe wall, slit-shaped pores cut in a rubber disk, or pores of a porous ceramic tubular body. Has been attempted, and it is said that the amount of dissolved oxygen in the wastewater depends on the supply amount of fine bubbles controlled by those pores. In the latter method,
There are so-called “rotating blade type”, “jet type”, “single tube aeration type” and the like.For example, air bubbles are made to collide with rotating blades to break up bubbles. There are methods such as generating a phase jet and dividing bubbles in the entrainment process of bubbles and water, and dividing bubbles by colliding a two-phase flow of air and water with a projection. It is said that the amount of dissolved oxygen in the gas depends on the rotation speed of the rotating blades, the speed of the bubble jet, and the collision speed of the two-phase flow with the projection. In aeration using an aerator having these functions, basically, necessary adjustments are made according to the amount of air supplied and the number of aerators installed.

However, in order to develop an energy-saving high-performance wastewater treatment apparatus for the purpose of advanced wastewater treatment, it is necessary to generate a large amount of particularly fine oxidizing gas bubbles and to control the amount of such bubbles. There is.

[0005] However, the aeration of the above-described method is mostly a diffuser method by jetting or a method of generating bubbles by shearing with a rotating blade or a projection, and thus has the following various disadvantages. For example,
In the method of blowing from the diffuser tube, diffuser plate, and diffuser cylinder, no matter how fine pores are provided, due to the surface tension of the bubbles when the bubbles are blown out of the pores, the diameter is about several mm. However, there is a disadvantage that it is impossible to generate bubbles having smaller diameters and smaller bubbles. Further, as a drawback of such an air diffusion method, there is a problem of clogging and a problem of an increase in power cost caused by the long-time operation. On the other hand, in the rotating blade system, a high rotation speed is required to generate cavitation, and there are problems of power cost and corrosion and vibration problems of the blade which rapidly progress with the occurrence of cavitation. In the jet method, the diameter of fine bubbles and the amount of
No significant advantage over conventional aerators is observed. Further, in the method in which the gas-liquid two-phase flow collides with the projection, there is a problem that generation of fine bubbles is small.

[0006] In the aerator of the conventional wastewater treatment apparatus having the above-mentioned drawbacks and problems, the amount of fine bubbles generated is small, so that the residence time of the bubbles in the wastewater is shortened, and oxygen dissolution in the wastewater is reduced. No increase in volume could be expected. Furthermore, since the diameter and the generation amount of the fine bubbles cannot be easily controlled, there is a problem that the purification treatment of the wastewater cannot be efficiently performed.

That is, the above-described aerator has the following problems. . A large amount of fine bubbles having a diameter of 1 mm or less and up to about several tens of micrometers cannot be generated uniformly, and dramatic promotion of gas-liquid renewal cannot be achieved. . The diameter, distribution, and generation amount of the bubbles cannot be easily mechanically controlled as necessary. . Without the stirrer, it is not possible to form the necessary circulating flow in the wastewater treatment apparatus and to provide the stirring action. . Pressure loss cannot be reduced due to the presence of rotating blades and projections. . When the gas-liquid two-phase flow collides with the rotating blades and projections, microorganisms and activated sludge are destroyed, which may hinder formation and maintenance of a biological environment required for sewage purification. . The continuous air diffusion causes clogging, and the air diffusion efficiency is reduced, thereby increasing the pressure loss. For this reason, long-term continuous operation and significant reduction in operating costs cannot be achieved. . The size of the device including the aerator and the compressor is large, and there are restrictions on the installation, and miniaturization cannot be achieved. . By controlling the diameter, distribution, and generation amount of bubbles, it is difficult to perform stirring in the aeration tank, oxidize COD components, and optimally control the growth of aerobic microorganisms.

[0008]

The present inventors have made intensive studies to solve the above-mentioned problems of the prior art, and as a result, provided an energy-saving aerator capable of easily supplying fine bubbles to drainage. Developed wastewater treatment equipment. That is, the present invention is a wastewater treatment device as described below. A first invention is a porous flow drainage transfer pipe exposed in the atmosphere, or
One hydrocephalus difference is provided a waste water treatment apparatus characterized by comprising a suction type aerator formed by arranging the second invention, hydrocephalus porous flow drainage transfer tube of the middle side of the gas supply tube
A waste water treatment apparatus characterized by comprising a suction type aerator made by disposing provided the difference to a third aspect of the present invention, hydrocephalus
A waste water treatment apparatus characterized by comprising a suction type aerator which the middle side of the fluidized effluent transfer pipe formed by arranged with a difference formed by disposing a porous gas supply pipe. The fourth invention is
The wastewater treatment device according to any one of the first to third inventions, wherein the communication hole of the porous pipe is an irregular communication hole, and the fifth invention is directed to a porous flowing drainage transfer pipe or /
The wastewater treatment apparatus according to any one of the first to fourth inventions, wherein the porous gas supply pipe is a porous ceramic pipe.

A sixth aspect of the present invention is the drainage system according to any one of the first to fourth aspects, wherein the porous flowing drainage transfer pipe and / or the porous gas supply pipe is a porous metal pipe. A seventh aspect of the present invention is the treatment apparatus, wherein the communicating hole of the porous flowing drainage transfer pipe and / or the porous gas supply pipe has a diameter of 5 mm.
The wastewater treatment device according to any one of the first to sixth inventions, wherein the wastewater treatment device is not more than 00 μm,

[0010] An eighth invention is any of the second, or 4 to 7 of the invention is characterized by being circumferentially flow drainage supply pipe to the pipe-shaped or box-shaped gas supply chamber of the porous A wastewater treatment device described in

In the above invention, firstly, in the supply of outside air using an irregular porous tube such as ceramics, the suction system utilizing the head difference causes a considerably smaller pressure loss than the jet system. . This is due to the fact that the surface area of the outer peripheral wall surface of the pipe is always larger than the surface area of the inner peripheral wall surface due to the presence of the pipe thickness. Therefore, the head difference of the present invention using a porous pipe was utilized. According to the suction method, the efficiency of generating bubbles in the wastewater is greatly improved. In this case, when the tube wall thickness of the porous tube is constant, the smaller the inner diameter of the tube, the better the gas suction efficiency. Secondly, in the conventional ejection method, even if the diameter of the pores of the irregular porous tube made of ceramics or the like is reduced to about μm, the diameter of bubbles generated therefrom is on average about several mm. According to the suction type aerator according to the present invention, the average diameter of generated bubbles can be reduced to several hundreds μm to several tens μm. Therefore, the contact area between the wastewater and the oxidizing gas bubbles can be increased to about 10 to 100 times that of the conventional method, and the residence time of the bubbles can be increased to 10 to 100 times. Can be increased.

Third , by controlling the pressure of the gas sent to the flowing drainage transfer pipe of the porous pipe, the amount of air bubbles sucked can be adjusted without changing the flow rate of the drainage. By controlling the amount of generated bubbles, high efficiency of wastewater treatment can be achieved. Fourth , the pressure energy required for gas suction from the porous tube only needs to exceed the pressure loss head of the porous tube, and a very small pressure energy is sufficient. Usually, a head difference of about 50 cm is sufficient. Fifth , in the conventional method in which aeration is performed by colliding with high-speed rotating blades or projections, there is a problem that microorganisms and activated sludge are destroyed, but according to the present invention, such a problem does not occur at all. Sixth , as the external gas is uniformly sucked near the inner wall of the porous tube, a flow is formed perpendicular to the wall toward the center of the tube. This flow acts in the direction in which the substance to be attached to the inner wall is peeled off, and as a result, the formation of clogging of the porous tube is less likely to occur. Even if clogging occurs, so-called "backwashing" can be performed by adding a method of reversing the pressure difference between the inside and outside of the porous tube for recovery.

[0013] Seventh, but requires a compressed air supply device, such as a conventional compressor or blower, water according to the present invention
Since it is a suction type using a head difference , such a device can be unnecessary. Further, the porous fluid drainage pipe section can be easily unitized. By attaching joints to both ends of the transfer tube, or.
A unit body is manufactured by penetrating and attaching a porous flowing drainage supply pipe to a transparent plastic gas supply casing, and bonding and sealing the contact between the through-hole part of the casing and the transfer pipe. can do. And the above. In the unit body, if the inner porous tube is made of ceramic in particular, if the outer housing is made of a material with high mechanical strength such as plastic or metal, it also functions as a reinforcing member.
Since capable of, it is possible to prevent the breakage of the porous ceramic tube. As the material of the porous tube, in addition to porous ceramic, a porous material such as a porous metal and a porous plastic can be used as appropriate, but in any case, the pores of the porous portion become communication holes. It is necessary to be.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described below with reference to the drawings. Fig. 1 utilizes the head difference according to the present invention
FIG. 1 is an explanatory diagram showing the overall configuration of a wastewater treatment apparatus provided with a suction type aerator.
0, first enter the sedimentation tank 52 via the sedimentation tank 51, then
It is introduced into the aeration tank 53. In the aeration tank 53, the water in the tank is sucked up by the pump P2, temporarily stored in the auxiliary tank 54, then formed into a circulation path in which the water is dropped and returned again to the aeration tank 53. The aerator 30 is mounted. From the upper end of the aeration tank 53, a part of the aerated water is led out and introduced into the final sedimentation tank 55, and then the supernatant water is introduced into the chlorine sterilization tank 57, from which purified water is taken out. A small amount of returned sludge 56 is taken out from the bottom of the final settling tank 55 and supplied to the aeration tank 53. P1 to P3 are pumps. In the above wastewater treatment apparatus, since a suction type aerator made of a porous tube is used as an aerator, first, a large amount of pressure loss energy is not required as in the conventional method using a diffuser tube, and a porous tube is used. Due to the method of sucking gas into water through the gas, bubbles of very small diameter are generated instead of bubbles of large diameter as in the case of a diffuser. Therefore, the contact surface area between the air bubbles and the drainage water increases, and the efficiency of dissolving the gas in water is greatly improved.
As a result, COD and BOD of wastewater can be reduced with high efficiency.

FIG. 2 is a schematic sectional view of one embodiment of the vertical aerator of the wastewater treatment apparatus according to the present invention. In FIG. 2, 1 is a ceramic porous tube, 2 is an acrylic resin gas supply tube, 2 'is a flange, 3 is a gas inlet, 4
Is a fluid drainage transfer pipe, 4 'is a fluid drainage containing fine bubbles
Pipe, 4 " for flange, 5 for fasteners (bolts, nuts),
6 is a packing. In the figure, when the drainage flows in the flowing drainage transfer pipe 4 from the direction of the arrow, the gas from the gas inlet passes through the porous pipe wall and flows through the inside of the porous drainage pipe 1 (drainage). And supplied as fine bubbles. That is, the inner wall portion of the porous pipe has a negative pressure due to the head of the flowing wastewater, and the gas from the gas inlet 3 is sucked as fine bubbles into the flowing wastewater through the porous wall.

The relationship between the pore diameter of the pores of the porous tube and the diameter of the generated fine bubbles is as shown in FIG. 7 as a result of the experiment.
That is, the distribution of the diameter of the generated microbubbles is about three times the distribution of the pore diameter of the porous tube. However, the measurement conditions in FIG. 7 are that the outer diameter of the porous tube is 13.5 mm and the inner diameter is 7 m.
m, the length is 120 mm, the average pore diameter is 22 μm,
The amount of flowing water in the flowing drainage transfer pipe is 1.10 l / sec. It is. As a result of another measurement experiment, it was found that the diameter of the generated fine bubbles was about 2 to 4 times the average pore diameter of the porous tube.

In the vertical type aerator, each member is easy to disassemble and therefore easy to assemble. The outer diameter of the porous tube 1 made of ceramics is almost equal to the inner diameter of the narrowest portion of the gas supply tube 2 made of acrylic resin. By making them the same, both can be slid and inserted freely, which facilitates assembly and disassembly. In this configuration, the gas supply pipe 2 supports the porous pipe 1 so as to sandwich the porous pipe 1 and advantageously acts as a reinforcing member for reinforcing a fragile porous pipe such as a ceramic pipe. The vertical type aerator of this configuration may be turned horizontally to form a horizontal type, but in this case, the hydrodynamic gradient line formed by the pressure difference between the upstream and downstream may cause the downstream aerator to be in a low state. Should do it.

If a reducing tube is used, it can be used as it is as a horizontal type. FIG. 3 is a schematic sectional view of one embodiment of the horizontal aerator. In the figure, 1
Is a porous tube made of ceramics, 2 is a gas supply tube made of acrylic resin, 2 'is a flange, 3 is a gas inlet, 4 is a downstream flowing drainage transfer tube, and 4' is a fine bubble-containing flowing drainage transfer.
Pipe, 4 " for flange, 5 for fasteners (bolts, nuts),
Reference numeral 6 denotes a packing, and reference numeral 7 denotes a reducing pipe which is also an upstream flowing drainage transfer pipe. In this figure, when the drainage flows in the direction of the arrow in the upstream contraction pipe 7, the negative pressure becomes maximum at the rear inner wall surface of the contraction pipe 7, and the gas from the gas introduction port is formed in the porous pipe 1. After passing through the porous tube wall, it is supplied as fine bubbles to the internal flowing drainage (drainage). The aperture angle of the retraction tube 7 is usually preferably about 10 to 30 degrees.

FIG. 4 is a conceptual diagram showing a horizontal arrangement of the aerator and a siphon arrangement in which gas is sucked as fine bubbles into the flowing waste water from the porous tube. In the figure, 30 is an aerator according to the present invention, 4 is a flowing drainage transfer pipe, 11 is a drainage storage tank, 12 is an aeration-treated drainage storage tank, HL is a hydrodynamic gradient line, and H is a head difference. In the figure, when waste water is introduced from the waste water storage tank 11 through the flowing waste water transfer pipe 4 into the aerator 30, the outside air is sucked and supplied into the waste water as fine bubbles due to the head difference H and the hydraulic gradient line HL. Then, the water is supplied to the aeration-treated wastewater storage tank 12 disposed at a lower position through the flowing wastewater transfer pipe 4.

FIG. 5 is a schematic sectional view of another embodiment of the vertical aerator. In the figure, the porous tube 1 is a gradually expanding tube, and the porous tube 1 is attached to the expanded portion. According to the method of the present example, since the diameter of the lower part of the fluidized drainage transfer pipe is larger than that of the upper part, the suction force at the expanded part of the porous pipe is further enhanced.
In the figure, when the drainage falls from the upper drainage storage tank 11 and enters the gradually expanding pipe 8, the negative pressure becomes large on the inner wall surface of the porous pipe 1 of the gradually expanding pipe 8, and the gas from the gas inlet is discharged. After passing through the wall of the porous tube 1, it is supplied as fine bubbles to the internal flowing drainage (drainage).

FIG. 6 is a schematic sectional view of another embodiment of the vertical type aerator. In this figure, a cylindrical gas supply device 9 having a porous tube 1 is provided inside a flowing drainage supply tube 4. According to this example system, the outside air is
Through an air guide pipe 10 connected to the gas supply 9 through the fluid drainage transfer pipe 4, fine bubbles are sucked and supplied into the drainage as fine bubbles from the outer wall surface of the porous pipe 1.

As described above, in the present invention, a suction method using a porous tube is employed, so that external gas is sucked from a porous tube such as ceramics, so that a fine water having a diameter of several hundred μm to several tens μm can be introduced into the fluidized drainage transfer tube. And the amount of the bubbles can be controlled. In adjusting the generated bubbles, the amount of bubbles can be increased by increasing the negative pressure in the fluidized drainage transfer pipe or by increasing the air pressure in the gas supply pipe. Can be performed by reducing the diameter of the communication hole of the porous tube.

[0023]

As has been described in detail in the embodiments and the like, according to the present invention, many excellent functions and effects as described below are exhibited. (1). According to the aerator according to the present invention, the pressure loss becomes considerably smaller than that of the conventional jet type aerator, and the efficiency of generating bubbles in the flowing wastewater is greatly improved. (2). In the conventional ejection method, even if the diameter of the pores of an irregular porous tube made of ceramics or the like is reduced to about μm, the diameter of bubbles generated therefrom is about several mm on average. According to the suction type aerator, the average diameter of the generated bubbles can be reduced from several hundred μm to several tens μm. Therefore, the contact area between the waste water and the bubbles such as the oxidizing gas can be extremely increased, and the residence time of the bubbles in the waste water can be significantly increased. As a result, the amount of dissolved oxygen in the waste water can be dramatically increased. Can be increased. ( 3 ). By controlling the pressure of the gas sent to the flowing drainage transfer pipe of the porous pipe, the amount of air bubbles sucked can be adjusted without changing the flow rate of the drainage water. Higher processing efficiency can be achieved.

( 4 ). The pressure energy required for sucking the gas from the porous tube only needs to be higher than the pressure loss head of the porous tube, and extremely small pressure energy is sufficient, and energy saving operation is possible. ( 5 ). As the external gas is uniformly sucked near the inner wall of the porous tube, a gas-liquid flow is formed perpendicular to the wall toward the center of the tube, and this flow adheres to the inner wall of the porous tube. It acts in the direction in which contaminants and the like to be removed are peeled off. As a result, clogging of the porous tube is less likely to occur. ( 6 ). A compressed air supply device such as a compressor or a blower as in the conventional system is not required, and only the difference in water head may be secured. ( 7 ). The porous fluidized drainage supply pipe is easy to be unitized. For example, the porous fluidized drainage supply pipe is attached to a transparent plastic gas supply casing by penetrating the porous fluidized drainage supply pipe, and the casing has a through hole and a transfer pipe. A unit body can be manufactured by bonding and sealing a contact portion with the unit. And
When the inner porous tube is made of ceramics in particular, if the outer casing is made of a material having high mechanical strength such as plastic or metal, the outer case can function as a reinforcing member. Can be prevented from being damaged.

[Brief description of the drawings]

FIG. 1 is an explanatory view of the entire configuration of a wastewater treatment apparatus provided with a suction type aerator using a head difference according to the present invention.

FIG. 2 is a schematic sectional view of one embodiment of a vertical aerator of the wastewater treatment device.

FIG. 3 is a schematic sectional view of one embodiment of a horizontal aerator.

FIG. 4 is a conceptual diagram in which an aerator is placed laterally and arranged in a siphon, and gas is sucked as fine bubbles from a porous tube into flowing wastewater.

FIG. 5 is a schematic sectional view of another embodiment of the vertical aerator.

FIG. 6 is a schematic sectional view of another embodiment of the vertical aerator.

FIG. 7 is a graph showing the relationship between the pore diameter of the pores of the porous tube and the diameter of the generated fine bubbles.

[Explanation of symbols]

1: Porous pipe made of ceramics, 2: Gas supply pipe made of acrylic resin, 2 ': Flange, 3: Gas inlet, 4: Fluid drainage transfer pipe, 4': Fine bubble mixed fluid drainage transfer pipe,
4 " : Flange, 5: Fastener (bolt, nut), 6:
Packing, 7: Reducing pipe, 8: Reproducing pipe 9: Cylindrical gas supply, 10: Air guide pipe, 11: Drainage storage tank, 12: Aeration treated drainage storage tank, 30: Aerator, 50: Screen, 51: Sedimentation sand Tank 52: First settling tank, 53: Aeration tank, 54: Temporary auxiliary tank 55: Final settling tank, 56: Returned sludge, 57: Chlorine sterilization tank P1 to P3: Pump HL: Hydraulic gradient line, H: Head difference

──────────────────────────────────────────────────続 き Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C02F 3/00-3/34 C02F 7/00 B01F 1/00-5/26

Claims (8)

(57) [Claims] 1. A wastewater treatment apparatus comprising a suction type aerator in which a porous flowing drainage transfer pipe is exposed to the atmosphere and provided with a head difference . 2. A wastewater treatment apparatus comprising a suction type aerator in which a porous flowing drainage transfer pipe is provided with a head difference provided inside a gas supply pipe. 3. A wastewater treatment apparatus comprising a suction type aerator provided with a porous gas supply pipe inside a fluidized drainage transfer pipe provided with a head difference . 4. A waste water treatment apparatus of claims 1, wherein the pores of the porous tube is irregular passage according to any one of the three. 5. A porous gas supply pipe of the fluidized effluent transfer pipe and / or porous is, waste water treatment apparatus according to any one of claims 1 to 4, characterized in that a porous ceramic tube . 6. The wastewater treatment device according to to the porous flow drainage transfer tube or / and the porous gas supply tubes of claims 1 characterized in that it is a porous metal tube any one of four. 7. A waste water according to any one of claims 1, wherein the pore diameter of the porous flow drainage transfer tube or / and the porous passage of the gas supply pipe is 500μm or less 6 Processing equipment. 8. Claim 2, or 4 to 7 any one of to, characterized in that the porous flow drainage supply pipe to the pipe-shaped or box-shaped gas supply chamber formed by circumferentially Wastewater treatment equipment.